Effect of post-impulse depression on background firing of sympathetic preganglionic neurons. (1) Many of the preganglionic neurons responsible for sympathetic tone in the cat exhibit a characteristic irregular background spike activity with a low repetition rate. The properties of this activity, described by the interspike interval histogram, can be explained as the result of the responses of the neurons to random synaptic imputs. (2) Serial interspike interval correlation was used to show that additive post-impulse depression in preganglionic neurons does not enter into the timing of typical low-rate, irregular background firing. However, if cells are accelerated by anitdromic tetanization, a depressive recovery process accumulates to cause a prolonged silent period after driving of the cells has ceased. If cells are accelerated, by the action of their synaptic inputs, to rates higher than their usual basal rates, serial post-impulse depressions overlap, and summate to cause a temporal interaction between neighboring pulses which is observable by serial interval correlation. (3) By observing the effect of antidromic responses occurring at various intervals after a background spike, we showed that the time course of the summative part of post-impulse depression is shorter than the interspike intervals typically encountered in background firing. (4) At higher-than-basal levels of sympathetic activity, occurring spontaneously or during antidromic stimulation, successive post-impulse recovery periods overlap and sum to impart a negative correlation of serial interspike intervals. At the levels of sympathetic activity existing in waking animals, the damping effect of cumulative post-impulse depression is probably an important factor in stabilizing sympathetic tone.


Effect of insulin hypoglycemia upon cerebral energy metabolism and EEG activity in the rat. Anesthetized ventilated rats were subjected to insulin-induced hypoglycemia (50 units/kg i.v.) while EEG, ECG, mean arterial pressure, blood gases, arterial pH and rectal temperature were controlled. Animals were sacrificed by rapid transcalvarial freezing of the brain in situ. Glucose, pyruvate and lactate were measured in blood, CSF and cortical tissue, in which additionally glycogen, phosphocreatine, ATP, ADP, AMP, aketoglutarate (aKG), glutamate, oxalacetate, aspartate, ammonia and water content were estimated. ATP/ADP ratio, energy charge (ECh) energy reserve, NADH/NAD+ quotient and intracellular pH were calculated. ECh does not correlate with either dysfunction of carbohydrate depletion, but declines in a threshold fashion when tissue glucose has fallen by over 97% and glycogen by over 60%. The EEG correlates with the degree and duration of carbohydrate depletion in cortical tissue. An isoelectric EEG occurs pari passu with the fall of the ECh. Increase in ammonia and decrease in aKG and Glut are supportive evidence of intrinsic substrate. Lactate decrease during hypoglymecia is not reversed by super-imposed hyqoxia.


Microwave alteration of the blood-brain barrier system of rats. Rats were exposed to 1.3 gHz microwave energy to assess the uptake of several neutral polar substances in certain areas of the brain. A quantitative, radioactive isotope method, which uses an internal standard, was employed to measure the loss of test substances to brain tissue. Single, 20 min exposure, to either pulsed or continuous wave (CW) microwave energy induced an increase in the uptake of D-mannitol at average power densities of less than 3.0 mW/sp. cm. The permeability change was greatest in the medulla, followed, in decreasing order, by the cerebellum and hypothalamus, with small or negligible changes in the hippocampus and cortex. Permeability increases were observed for mannitol and inulin but not for dextran. Increased permeability was observed both immediately and 4 h after exposure, but not 24 h after exposure. After an initial rise, the permeability of cerebral vessels to saccharides decreased with increasing microwave power. Differences in the level of uptake occurred between CW energy and pulsed energy of the same average power. Microwaves of the same average power but different pulse characteristics also produced different uptake levels. Our findings suggest that microwaves induce a temporary change in the permeability for small molecular weight saccharides in the blood-brain barrier system of rats.


Impairment of DNA synthesis in Gunn rat cerebellum. Brain DNA synthesis was developmentally investigated in Gunn rat with marked cerebellar hypoplasia due to hereditary hyperbilirubinemia. In this mutant rat, the Purkinje cell was nearly selectively affected in the cerebellar cortex by bilirubin. The impaired DNA synthesis was observed in homozygous (jj) Gunn rat cerebellum, in which the DNA content and [3H]thymidine incorporation rate into DNA decreased after 10 days of age compared to those in the heterozygous (Jj)littermate. In contrast, these impairments were not found in the non-cerebellar parts of the brain and liver of jj Gunn rat. The activity of cerebellar thymidine kinase in jj Gunn rat decreased from a very early stae, being 80% of Jj rat at 6 days, and 50% at 10 days of age. The enzyme activity was not affected in the non-cerebellar parts of the brain. Although bilirubin competitively inhibited cerebellar thymidine kinase activity in vitro (15% at 10(-5) M), such bilirubin level was found to be about 1000-fold that in vivo. Moreover, photo-degradation of bilirubin in jj cerebellum exhibited no improvement in thymidine kinase activity, and the presence of an enzyme inactivator was not suggested in jj cerebellum. These results seem to indicate that the induction of thymidine kinase might be affected in jj Gunn rat cerebellum. The possibility that the impaired DNA synthesis in the external granular cells in jj cerebellum may be due to Purkinje cell damage is discussed.


Subcellular distribution of radioimmunoassayable somatostatin in rat brain. A specific, sensitive and reproducible radioimmunoassay is described for measurement of somatostatin in brain tissue. The sensitivity of the assay is 10 pg/tube and recovery of synthetic somatostatin added to brain homogenates was 95.8 +/- 6.2%. Dilution of tissue extracts from various brain regions showed parallelism in standard curves with labelled somatostatin. Somatostatin is shown to be widespread in the central nervous system with highest concentrations in hypothalamus, particularly the median eminence. Subcellular preparations of medial basal hypothalamus, preoptic area and amygdala indicate that over 70% of somatostatin immunoreactivity is localized to the synaptosome fraction. Recovery of activity in  the P2 pellet prior to separation on sucrose gradient is approximately 100%. It is hypothesized that somatostatin, in addition to being released into blood vessels of the median eminence, may also be liberated from nerve terminals in other brain regions.


Olfactory and vomeronasal deafferentation of male hamsters: histological and behavioral analyses. Deafferentation of the vomeronasal system by cutting the vomeronasal nerves severely impaired mating behavior in 44% of male hamsters over a 1--2 month period of postoperative testing, but the remaining males mated normally after the surgery. Damage to the main olfactory bulbs, concomitant to vomeronasal nerve cuts, did not account for this behavioral difference. Subsequent deafferentation of olfactory system by intranasal infusion of zinc sulfate solution (5 g ZnSO4--7H2O in 95 ml 0.5% NaCl) had no effect on intromission or ejaculation latencies of sham vomeronasal cut males but eliminated mating behavior 2 days after treatment in males with bilateral vomeronasal nerve cuts. Some of these males recovered the behavior in 1--3 weeks of post zinc sulfate testing. Histological analyses of the olfactory mucosa in 7 males on day 2 after zinc sulfate showed that 89--97% of the mucosa had been destroyed in 6 out of 7 of the males and 78% in the seventh. We conclude that destruction of the vomeronasal system irreparably reduces arousal necessary for mating in some hamsters but in other males sufficient arousal for this behavior to occur is mediated through the olfactory system, presumably in conjunction with other sensory inputs. Subsequent removal of the olfactory input in these animals eliminates the behavior.


Rat hippocampal neurons in dispersed cell culture. An in vitro system has been developed for the study of isolated hippocampal neurons from 18- or 19-day rat fetuses. Following trypsinization the cells are plated out at low density on polylysine-treated coverslips in an enriched medium. The isolated neurons rapidly attach to the substrate and initiate process extension. Little reaggregation occurs and the number of non-neuronal cells present is minimal. Unless co-cultured with tissue explants the neurons survive for only a few days; in the presence of hippocampal explants the initial growth of the isolated cells is improved and their survival in culture is extended to about two weeks. Some of the cells in such cultures develop a characteristic branching pattern closely resembling that of maturing hippocampal pyramidal cells in vivo. There is a clear relationship between the stage of the cells' development and their growth in culture. Cells which had completed DNA synthesis about 48 h before dissociation, and which were in the process of migration to the cortical plate, survived best in our cultures. Early post-mitotic cells which were still within the ventricular zone and cells which had already reached the cortical plate grew poorly. This system should permit the study not only of process formation by these cells, but also of their capacity to form specific synapses in vitro and of the biochemical constituents of their surfaces.


Unit activity of amygdala and hippocampal neurons: effects of morphine and benzodiazepines. The effects of morphine sulfate and two benzodiazepine derivatives, chlordiazepoxide HCl and diazepam, were evaluated upon single unit activity of the amygdaloid nuclear complex and hippocampal formation in immobilized cats. All surgical procedures were performed under halothane anesthesia and all wound margins were infiltrated with Lidocaine after halothane withdrawal. Single unit activity was recorded extracellularly with platinum-iridium microelectrodes. Chlordiazepoxide HCl, 10.0-20.0 mg/kg i.v., or diazepam, 0.05-0.20 mg/kg i.v., suppressed spontaneous firing rates of the amygdala and the hippocampal neurons. In contrast, the spontaneous firing rates of neurons in these limbic structures were augmented by morphine sulfate, 0.50-2.00 mg/kg i.v. The morphine-induced augmentation of hippocampal neuronal activity was effectively antagonized by naloxone, 0.10-0.20 mg/kg i.v. However, naloxone, 0.20-0.40 mg/kg i.v., only partially suppressed the morphine induced augmentation of amygdala neuronal activity. In a dose-dependent fashion, chlordiazepoxide and diazepam administration prevented or antagonized morphine-induced augmentation of amygdala and hippocampal neuronal activity. Our results suggest that, in the cat, the amygdala and hippocampus may play an important role for morphine-induced behavioral responses. Moreover, our data imply that these two limbic structures may be the sites of tranquillizing actions of diazepam and chlordiazepoxide.


Nucleus raphe magnus inhibition of spinal cord dorsal horn neurons. In decerebrate cats, electrical stimulation of nucleus raphe magnus (NRM) of the medulla produced marked inhibition of spinal neurons in lumbosacral dorsal horn. Only neurons with high threshold inputs were inhibited. These cells were located in lamina I and in or near laminae V and VI. The duration of inhibition produced was related to the stimulus train length. An ipsilateral lesion of the dorsolateral funiculus at L1 markedly reduced the inhibition of neurons caudal to the lesion. Although NRM stimulation was the most effective, inhibition from more lateral sites could be obtained at higher stimulus intensities. NRM induced inhibition is probably mediated by a direct projection via the dorsolateral funiculus to spinal dorsal horn laminae I, II, V and VI. The results are discussed in relation to proposed mechanisms underlying the analgesia produced by NRM stimulation.


Specificity of adhesion between cloned neural cell lines. We have investigated the phenomenon of intercellular adhesion using cloned cell lines derived from the rat central nervous system. Adhesion is assayed by measuring the rate at which a suspension of labeled (probe) cells of one type adheres to monolayers of other cell types. In general a given probe cell such as the nerve line B50 will adhere rapidly to most other cell lines, providing little information about the specificity of the interactions. However, we discovered several methods of pretreating the B50 cells which specifically alter their rate of adhesion to various types of monolayers. Treating the B50 cells with trypsin, coating them with an antinerve antiserum, or simply lowering the assay temperature from 20 degrees C to 0 degrees C were 3 separate procedures which resulted in slower rates of adhesion of the B50 probe cells to 3 distinct subclasses of monolayers. These data suggest that different mechanisms are involved in the adhesion of B50 cells to the various other cell lines. To account for the differences, we postulate the existence of pairs of interlocking or complementary surface components on the cell lines, a concept that has also been valuable in understanding interactions in other systems. We discuss the characterization of these proposed components and outline their usefulness in categorizing the cell lines.


Evidence for a cholinergic fiber tract connecting the thalamus with the head of the striatum of the rat. Placement of electrolytic lesions in the zona incerta or parafascicular nucleus of the rat forebrain resulted in a marked reduction of choline acetyltransferase (ChAc) activity in the head of the striatum 2-4 weeks later. Lesions of the habenula did not cause this effect implying that concomitant destruction of the fasciculus retroflexus with the parafascicular nucleus was not responsible for the effects observed. The data suggest that there is a cholinergic fiber tract connection between the parafascicular nucleus of the thalamus and the head of the striatum in the rat forebrain.


Nembutal treatment of the VMH (rat): effects on feeding and sexual behaviour. In male rats two brain cannulae were implanted bilaterally and directed to an area just dorsal of the ventromedial hypothalamic nucleus. The behaviour of these animals was observed before and after the injection through these cannulae of either 1 micronl saline or 1 micronl Nembutal. Injections were performed under three behavioural conditions: (1) animal alone in cage with food, (2) animal in the presence of an oestrous female and (3) animal in cage with food and oestrous female. Following the Nembutal injection, sniffing and feeding are disinhibited temporarily in condition 1, whereas in condition 3 only sniffing, but not feeding, is disinhibited. In conditions 2 and 3 male sexual behaviour is not influenced by the Nembutal except for an increase of sniffing at the female. It is concluded that a temporary elimination of the VMH leads to a disinhibition of feeding only if the external conditions are favourable for feeding. The same elimination of the VMH does not influence the occurrence of male sexual behaviour under the conditions used in these experiments.


Midbrain raphe lesion in the newborn rat: II. Biochemical alterations in serotoninergic innervation. Electrolytic raphe lesion was performed in 4-6-day-old rats and the resulting changes of 5HT metabolism within the central nervous system were analyzed up to 9 months later. As soon as the 2nd day following the selective destruction of B7 and B8 nuclei, forebrain 5HT levels were decreased by more than 75%. This reduction persisted for at least 9 months with no sign of recovery. The time course of 5-HIAA decrease was parallel to that of the indoleamine so that the ratio of 5-HIAA over 5-HT levels in the forebrain of lesioned rats was similar to that estimated in controls, whatever their age. This result would suggest that the remaining serotoninergic neurons in the lesioned rats did not develop a compensatory hyperactivity. The raphe lesion induced no change in MAO activity and synaptosomal tryptophan uptake but a pronounce decrease in the Vmax of synaptosomal KHT uptake process in various forebrain areas occurred. The serotonin sensitive adenylate cyclase activity in colliculi homogenate was not altered by the lesion suggesting that this enzyme was probably located in postsynaptic membranes. In addition, this observation would indicate that 5-HT receptors which are linked to this adenylate cyclase did not become supersensitive following the selective degeneration of serotoninergic neurons. Animals without forebrain serotoninergic innervation might be of great interest to analyse the role of serotoninergic neurons in various functions (sleep, analgesia, thermoregulation).


Total and partial hypothalamic deafferentations for topographical identification of catecholaminergic innervations of certain preoptic and hypothalamic nuclei. After total deafferentation of the medial hypothalamus in the rat, noradrenaline concentration in the nucleus arcuatus and the eminentia mediana diminished to one-third. The same decrease of noradrenaline concentration resulted also from partial (anterolateral) deafferentation. Rostral and caudal cuts from the medial hypothalamus did not induce any change in the noradrenaline concentration of the two above-mentioned areas. This indicates that noradrenaline containing axons enter the medial basal hypothalamus laterally from the medial forebrain bundle. Total or partial deafferentation of themedial hypothalamus did not affect noradrenaline or dopamine concentrations in the nucleus preopticus medialis, the nucleus interstitialis striae terminalis, the nucleus hypothalamicus anterior and nucleus supraopticus. The catecholaminergic fibres supplying these regions do not pass the medial hypothalamus, but probably ascend laterally from it, in the medial forebrain bundle. The noradrenaline innervation of the nucleus dorsomedialis takes its origin in the ventral noradrenaline bundle and the fibres from the medial forebrain bundle ascend into the nucleus from the lateral side. After total or lateral deafferentation of the medial hypothalamus, that ransects the fibres running to the nucleus laterally, noradrenaline concentration decreases, apart from the nucleus located within or outside the deafferented island. In this case anterior or posterior deafferentation of the hypothalamus is ineffective. Total deafferentation did not change dopamine concentration in the nuclei of the medial basal hypothalamus, thereby furnishing evidence for its intrahypothalamic origin from the A12 cell group. However, after total deafferentation, some slight decrease of dopamine concentration could be observed in the median eminence. This suggests that the dopamine concentration in the median eminence does not originate exclusively from thenucleus arcuatus but to some extent originates from extrahypothalamic sites. After posterior deafferentation, which destroys the fibres of the incertohypothalamic dopamine system, dopamine concentration in the nucleus dorsomedialis decreases. After total deafferentation of the medial hypothalamus, which isolates the nucleus from the ventral nuclei (and so also from the A12 cell group) of the medial hypothalamus, the dopamine concentration in the nucleus dorsomedialis did not change.


Pulsatile growth hormone, prolactin, and thyrotropin secretion in rats with hypothalamic deafferentation. Fifteen minute sequential blood sampling of male rats via right atrial cannulae was used to examine the patterns of anterior pituitary hormone secretion following hypothalamic deafferentations. Growth hormone (rGH) profiles from rats with complete hypothalamic deafferentation (CC) showed persistence of episodic rGH secretion with greatly increased frequency and elevated trough values, but without apparent entrainment to the light-dark cycle. Anterior (AC) and posterior (PC) deafferentation had no effect on the normal 3 h periodicity of rGH secretory episodes, but light-dark entrainment was lost in AC rats. Prolactin (rPRL) secretion in CC rats remained at normal low baseline levels without secretory episodes, while in AC and PC rats, as in normal rats, bursts of rPRL secretion occurred, often temporally related to rGH bursts. Thyrotropin (rTSH) levels in CC rats were less variable, and lower than in normal rats, while rTSH secretory profiles appeared normal in AC and PC rats. These results suggest that the isolated medial basal hypothalamus (MBH) contains neural substrates for episodic rGH secretion, and to a lesser extent, for rTSH. It is hypothesized that excessive rGH secretion in CC rats results from surgery damaging the rhythmicity of the rGH releasing factor (GRF) michanism, so that both sustained secretion and more frequent bursts of GRF occur. An effective rPRL inhibitory mechanism remains intact within complete hypothalamic deafferentations, while episodic rPRL and rTSH secretion require intact lateral afferents to the MBH. Visual pathway connections to the MBH, which mediate light-dark cycle entrainment of episodic rGH secretion, appear to pass through the region of the anterior hypothalamic and suprachiasmatic nuclei.


Mapping the developing retinotectal projection in frog tadpoles by a double label autoradiographic techinque. Tadpoles of Xenopus at developmental stages 45-59 were given an intraocular injection of [3H]proline and an intraperitoneal injection of [3H]thymidine, killed either after a short (1-2 day) or long (16-37 day) survival period, and processed for autoradiography. In all cases, there was a regular pattern of labelling. In the retina, the proline-labelled cells were always central to the thymidine-labelled cell nuclei, and in the long survivors there was a sharp transition between the cells occupying the central labelled retina and the surrounding unlabelled cells at the retinal periphery. In the tectum, unlabelled optic axons were confined to a rostrolateral zone which was bordered caudomedially by a zone of labelled tectal cell nuclei, and in the long survivors there was a completely unlabelled zone at the caudomedial margin of the tectum. The size of the tectal zone of labelled axons was not significantly different in the long survivors from that in short survivors injected at the same stage of development. Labelled optic axons remained close to the tectal cells that were present before the time of injection and did not move later into the zone of cells added to the tectum in the survival period after the injections.


Brain cell surface antigens detected by anti-corpus callosum antiserum. When rabbits are injected with tissue homogenates of white matter from bovine corpus callosum, an antiserum is produced which reacts with the surface membrane of 20-30% of all cells obtained by trypsin-dissociation of cerebellum from 10-day-old mice. The antigen or set of antigens recognized by this antiserum is detectable on embryonic, early postnatal, and adult mouse brain, but not on liver, spleen, kidney, thymus and sperm. The antigen is expressed in different regions of the brain and also, in decreased amounts, on retina. In histological sections of cerebellum from 21-day-old mice the antigen is predominantly localized in white matter tracts. Whereas nervous tissue from chicken and rabbit does not carry detectable levels of the antigen, rat, bovine and human brains are antigen-positive.


Midbrain raphe lesion in the newborn rat I. Neurophysiological aspects of sleep. Electrolytic lesions of the anterior raphe nuclei in the 4-6 day puppy rat were performed stereotaxically. The subsequent development of the sleep parameters in these animals was followed up to the second month of life. No difference could be found between the lesioned and control rats, neither in the qualitative nor in the quantitative characteristics of slow wave sleep (SWS) and paradoxical sleep (PS). However, when performing identical lesions on 3-5 week-old animals, a relative insomnia was obtained, more severe for PS than for SWS. The correlation of the neurophysiological data with the biochemical analysis of monoamines in the forebrain revealed that the serotoninergic (5-HT) system of the anterior raphe in the early lesioned animals was almost totally destroyed, with no recovery up to 9 months of age. Our results indicate that the anterior raphe nuclei are not functional during the first week of age, in regard to sleep control, whereas they do play an important role in sleep regulation after 3 weeks of age. Furthermore, some compensatory mechanisms which develop in the early lesioned animal as a consequence of the lesion, could explain the exhibition of normal sleep ontogenesis. The possible nature of these mechanisms is discussed in light of the monoaminergic theory of sleep control.


Mechanisms of excitation and inhibition in the nigrostriatal system. The extracellular responses of neurones in the neostriatum following single pulse stimulation of the substantia nigra were investigated in urethane anaesthetized rats. Low intensity stimulation (less than 10 V) evoked single large amplitude spikes while higher intensities (10-20 V) elicit a high frequency burst of small amplitude spikes or waves. When spontaneous or glutamate-induced large spikes are recorded, nigral stimulation causes their inhibition coincidentally with the development of a burst. If the burst is prevented, the inhibitory response disappears. Both the nigral evoked inhibition and burst response are unaffected by iontophoretically or systemically administered antonists of dopamine or by chemical lesions of the dopamine-containing nigral neurones. The monosynaptic activation of large amplitude striatal neurones, which could also be identified antidromically by stimulation of the globus pallidus, was reversibly blocked by dopamine antagonists. It is concluded (a) that the burst responses are induced through the antidromic excitation of striatonigral axons within the striatum; (b) that the striatal neurones thus activated are inhibitory interneurones and (c) that the dopamine-containing neurones of the nigra make excitatory synaptic contact with a population of striatal output cells, some of which at least project to the globus pallidus.


Ultrastructural characteristics of the brain and blood-brain barrier in experimental seizures. During experimental seizures, the blood-brain barrier (BBB) is broken; tracer substances such as I131-albumin, Evans blue and horseradish peroxidase (HRP) geographically locate the barrier breakdown primarily in the diencephalon. Using rats, we have induced seizures with electroshocks and demonstrated the breakdown of the BBB with Evans blue and HRP. We have shown that (1) the BBB breakdown is proportional to the number of electroconvulsant shocks (ES) given; (2) the mechanism of increased barrier permeability is primarily by micropinocytosis in the cerebral capillaries, arterioles, and, to a lesser extent, venules; and (3) the stimulus for micropinocytosis and hence BBB breakdown is associated with the abrupt rise in systemic blood pressure and cerebral vasodilatation that accompanies each ES. If the systolic hypertension is abolished via cervical cordotomy, there is little to no breakdown in the BBB.


Distribution of high affinity sodium-independent [3H]gamma-aminobutyric acid [3H]GABA binding in the human brain: alterations in Parkinson's disease. The regional distribution and properties of the sodium-independent "specific" binding of [3H]GABA to membranes prepared from human brains (control and Parkinsonian patients) have been investigated. The affinity of [3H]GABA for the binding site was similar for human cerebellar cortex (Kd = 3.4 x 10(-7) M) and whole rat brain brain (Kd = 5.1 x 10(-7) M) and was inhibited by bicuculline (ID50 = 2.2 X 10(-5) M). In the normal human brain the cerebellar cortex demonstrated the highest number of binding sites, in accordance with the large number of GABA interneurons in this structure. The hippocampus also displayed a high capacity to bind [3H]GABA, whereas cerebral cortical areas showed a lesser capacity. [3H]GABA binding was similar in many regions of the basal ganglia (amygdala, putamen, caudate or accumbens) but was lower than that for the cortical regions. The binding of [3H]GABA to membranes from the substantia nigra, thalamus and internal or external pallidum was lower than for the above regions. Subcortical white matter did not exhibit specific binding for [3H]GABA. In membranes prepared from Parkinsonian patients [3H]GABA binding was greatly decreased in the substantia nigra, but not in other brain areas examined. From this observation it was concluded that there are [3H]-brain areas examined. From this observation it was concluded that there are [3H]-GABA binding sites on the cell bodies (or dendrites) of the nigral dopamine neurons.


Crossed sacculo-ocular pathway via the Deiters' nucleus in cats. Single unit recordings were made in the Deiters' nucleus of cats in response to electrical stimulation of the superior area of the contralateral saccule and the ipsilateral oculomotor (IIIrd) nuclear complex. Correct placements of the stimulating and recording electrodes were identified by upward movements of the eyeballs associated with characteristic field potentials in the Deiters' nucleus. Stimulation of the contralateral saccule induced a negative N wave followed by positive P1 and P2 potentials. One hundred twenty-two units responded to contralateral saccular stimulation with a mean latency of 2.48 +/- 0.06 msec (SEM). Of these, only the responses of 31 cells could be made to collide with antidromic spikes evoked from ipsilateral IIIrd nuclear stimulation. This implies that the crossed sacculo-ocular pathway would involve at least four neurons with one commissural cell interposing between the bilateral vestibular nuclei.


Cerebral slow waves related to the perception of pain in man. Significant amplitude and temporal augmentation occurred in later time segments of human somatosensory evoked responses (60-700 ms) when percutaneous electrical pulse stimulation, delivered to finger, toe, or lip, indicated subjectively both crossing of a perceptual pain threshold and somatotopic movement associated with a noxious, qualitative change. Sequential pseudorandomizing of stimulus intensity (noxious and nonnoxious) or modality (contingent acoustic clicks) suggested that the waveform changes represented, at least in part, stimulus-specific information due to differential activation of peripheral fiber systems, rather than stimulus-nonspecific processing of event significances. The late waves were localizable, on scalp, to parietal and vertex regions, with insignificant contralateralization for finger stimuli. Their augmentation was related to subjective reports rather than to physical stimulus parameters, confirming previous data on potentially noxious mechanical stimulation of digits and palm, and another laboratory's noxious stimulation of tooth pulp. Subsequent data from a third laboratory, resulting from noxious laser stimulation of forearm, have replicated this late, slow-wave activity.


Behavioral correlates of denervation and reinnervation of the hippocampal formation of the rat: recovery of alternation performance following unilateral entorhinal cortex lesions. Following unilateral lesions of the entorhinal cortex (E.C.) of the rat, cells in the dentate gyrus which have been deprived of their normal ipsilateral input are reinnervated in part by axons from the contralateral E.C. The proliferation of this crossed projection occurs largely between 8 and 12 days postlesion. The present experiments analyze changes in alternation behavior which occur during this period of afferent proliferation. Rats were trained to alternate responses (L-R) in a T-maze for food reward. Bilateral E.C. lesions resulted in a persistent deficit in alternation performance which did not recover after over 50 days of postoperative testing. Unilateral E.C. lesions, however, resulted in a transient deficit in alternation which recovered over time to preoperative levels. For example, animals permitted a 10-day recovery before the initiation of postlesion testing exhibited no more of a performance deficit than following a 10-day no-training period alone. However, animals permitted only a 3-day postoperative recovery were impaired in the alternation task until 10-12 days postlesion, despite daily training. Thus, recovery of performance following unilateral lesions was dependent on postlesion time rather than the amount of testing/retraining. Since bilateral lesions resulted in a persistent performance deficit while unilateral lesions resulted in a deficit with recovery, we hypothesize that behavioral recovery might be related to the reinnervation of the dentate gyrus by the contralateral E.C. To test this hypothesis, secondary lesions were placed in operated-recovered animals. Secondary lesions of the surviving E.C. resulted in a deficit in alternation performance similar to that following one stage bilateral lesions. In addition, secondary lesions of the dorsal psalterium (the fiber tract which carries the corssed E.C.-dentate projections) also disrupted performance in operated-recovered animals. Primary lesions of the dorsal psalterium alone had only slight and transient effects on alternation performance, however. Thus, the time course of the recovery, the results following bilateral lesions, and the results of secondary lesions are all consistent with the hypothesis that recovery of alternation performance following unilateral E.C. lesions may depend upon the reinnervation of the dentate gyrus by the contralateral E.C.


Behavioral correlates of denervation and reinnervation of the hippocampal formation of the rat: open field activity and cue utilization following bilateral entorhinal cortex lesions. Bilateral lesions of the entorhinal cortex (E.C.) of the rat result in persistent deficits in both spontaneous and reinforced alternation. The present study analyzes the nature of this impairment. To determine if changes in exploratory activity accompanied the deficits in alternation, open field activity was measured daily from 2-22 days following bilateral E.C. lesions. Such lesions resulted in a pronounced transient increase in open field activity which peaked between 5 and 7 days postlesion, but subsequently decreased to near preoperative levels at approximately 11 days postlesion. Alternation performance was also analyzed, to determine which cues are utilized to make the alternation, and whether cue utilization is affected by bilateral E.C. lesions. Utilizing a plus (+) maze, animals readily learned to alternate goal arms, but even with extensive training, failed to learn to alternate turns (left and right). However, the ability to identify the two goal arms in a nonalternation situation (which does not require short term recall of the preceding trial) was not permanently impaired by bilateral E.C. lesions. Since bilateral E.C. lesions do not result in persistent deficits in the ability to identify the two goal arms, but do disrupt alternation performance, we hypothesize that the deficit in alternation might reflect an inability to recall which arm was chosen on preceding trials. The implications of these results for an understanding of the behavioral consequences of postlesion reorganization of neuronal circuitry are discussed.


Alterations by estrogen and hypothyroidism in the effects of septal lesions on lordosis behavior of male rats. Earlier experiments indicated that chronic exposure to estradiol benzoate (EB) following septal lesions can increase the subsequent levels of female sexual behavior in male rats tested several months later following priming doses of EB. However, the present study demonstrates that a single injection of a large dose of EB (50 microng) two days after septal destruction did not modify subsequent responsiveness to EB priming in male rats relative to sham operated controls. Yet male rats given 10 daily injections of 5.0 microng EB/day immediately following a septal lesion were more responsive to EB than oil treated controls when tested later for lordosis behavior. Therefore, the capacity for EB to alter the behavioral effects of septal lesions on lordosis behavior in male rats is related to both chronic administration and a period of susceptibility to some action of EB during the immediate post-lesion period. In two additional experiments, chronic hypothyroidism induced by propylthiouracil or thyroidectomy was also found to modify the effects of septal lesions on female sexual behavior of male rats. These latter results indicate that EB is not unique in its capacity to alter the behavioral effects of septal lesions in male rats, and are consistent with the view that both EB and hypothyroidism may interact with some dynamic process associated with recovery from brain lesions.


Filling of microelectrodes: an expedient solution. Micropipettes of small diameter filled with an electrolyte solution have been used widely to record electrophysiological potentials. Filling micropipettes is a major problem for many researchers. We describe an expedient and reliabel method of solving this problem by using parts that can be easily found in any research laboratory. Among the most important parts are; a vacuum pump, two stands, a container, tubes and a few clamps. The filling of these micropipettes can then be easily done by using negative pressure through the fine tip. With the drop in pressure distilled water or an electrolyte is forced downward inside the pipette thus filling the electiode tip.


Neuronal localization of pancreatic polypeptide (PP) and vasoactive intestinal peptide (VIP) immunoreactivity in the earthworm (Lumbricus terrestris). Nerve fibres and cell bodies displaying vasoactive intestinal polypeptide (VIP) or pancreatic polypeptide (PP) immunoreactivity were demonstrated in ganglia of the earthworm (Lumbricus terrestris). VIP cell bodies were found in the most anterior ganglion of the ventral nerve cord, the subpharyngeal ganglion. Immunoreactive nerves were seen running in the center of the cord until about the 10th segment. PP cell bodies were found in the cerebral ganglion where VIP was lacking, in the subpharyngeal ganglion and in more posteriorly located ganglia of the ventral nerve cord. PP nerve fibres could be followed below the 10th segment of the cord.


Nucleolar proliferation and cell size changes in rat supraoptic neurons following osmotic and volemic challenges. Subcutaneous injections of isotonic saline induced nucleolar proliferation in supraoptic neurons in animals sacrificed approximately 5 min postinjection. The magnitude of this proliferation was sustained 4 and 8 hr postinjection. Polyethylene glycol (PG) injections depleted blood volume 4 and 8 hr after the injection, but the percentage of SON cells with multiple nucleoli in these animals was not different from saline-injected controls. The anterior (SOa) portion of the SON in rats given 2% NaCl to drink instead of water for three days contained more cells with multiple nucleoli than controls. This effect was enhanced after five days ingestion, and accompanied by a similar response in the tuberal portion of SON (SOt). Rehydration for ten days after three days of 2% NaCl intake brought the percentage of cells with multiple nucleoli down to control levels. Cell area in SON cells paralleled nucleolar responses during dehydration and rehydration. The results demonstrate the sensitivity of nucleolar proliferation in SON to environmental changes ranging from osmotic to neurogenic stress.


A simple multi-purpose cannula system for access to the brain and/or systemic vascular system of unanesthetized animals. By utilizing a pedestal system mounted on the skull containing a cerebral guide cannula with hub, and a vascular catheter which is exteriorized within the pedestal, an easily made, multi-purpose system has been developed using materials which are available from any scientific or medical supplier. This technique is adaptable for use in a wide variety of animal species and can be used in unanesthetized or anesthetized preparations.


Effects of carbachol and nicotine injected into the cerebral ventricles on electromyogram of conscious cats. Carbachol and nicotine injected into the cerebral ventricles produced high amplitude and fast frequency activity in the electromyogram of conscious cats. Carbachol, much more than nicotine, caused bursts of such activity spaced at irregular time intervals accompanied by marked activity in the electrooculogram. In addition carbachol, but not nicotine, caused adynamia. The effect of nicotine laster 3-5 hr, while the effect of carbachol lasted up to 6 hr. The obtained results suggest that central muscarinic and nicotinic mediations are involved in the activation of the motor efferent system.


Brain calcium in the rabbit: site of action for the alteration of body temperature. Body temperature was recorded in the unanesthetized rabbit during push-pull perfusion of regions of the hypothalamus. Both the anterior and posterior hypothalamus were perfused with physiological solutions containing Ca++ in a concentration 2.0 or 5.0 times that of extracellular fluid. The animals were placed in an ambient temperature of 4.0 +/- 2.0degrees C for at least 1 hr before the perfusion and all experiments were carried out at this temperature. In the posterior hypothalamic area Ca++ produced a sharp fall in body temperature but did not cause body temperature to alter when it was perfused through the anterior hypothalamic area. These results indicate that the rabbit is similar to the cat and monkey since the effect of Ca++ on body temperature is localized to the posterior hypothalamic region.


The G-banding pattern of chromosomes in Ehrlich Lettŕe ascites tumor cells. The trypsin digestion-Giemsa staining technique was used to produce distinctive banding patterns in chromosomes of Ehrlich Lettŕe ascites tumor cells derived from a frozen culture originally begun from the ELD line. The chromosome numbers most frequently encountered in cells were 44 and 45. Four large marker chromosomes were identified in the karyotype. One of these was a large submetacentric chromosome, the banding pattern of which indicated its probable origin was from a pair of telocentric chromosomes. Using banding patterns and lengths, the chromosomes were classified into four groups--marker, paired, unpaired, and minute chromosomes.


X-ray induced pericentric inversions in Anopheles albimanus. Sixteen different pericentric inversions, ten on chromosome 2 and six on chromosome 3, have been isolated and characterized. The partial sterility in the inversion heterozygotes ranged from about 28 to 50%. Contrary to theoretical considerations, a curvilinear relationship exists between inversion length and partial sterility, whereby a reduction in sterility was noted for progressively longer inversions. The break-points are distributed randomly over the autosomes, but are observed more frequently in the areas of the salivary gland chromosomes where diffuse and broken bands of variable stainability are located.


Chromosome morphology during meiosis of normal and Robertsonian translocation-carrying rams (Ovis aries). A detailed description is given of the meiotic chromosomes of the normal ram (54,XY) and of the chromosomes at diakinesis-metaphase I in rams heterozygous for the t1, t2 and t3 and homozygous for the t1 and t3 Robertsonian translocation chromosomes. Analyses were made on diakinesis-metaphase I chromosomes in 309 cells from normal rams and 2402 cells from the Robertsonian translocation carriers. Hypomodal cell counts were due to missing chromosomal elements and hypermodal counts were due either to separation of the chromosomes of the sex bivalent or to separation of the components of an autosomal bivalent. Trivalent formation was characteristic for the heterozygous Robertsonian translocation carriers while the homozygous carriers had an additional large bivalent. An association between the sex bivalent and a small autosomal bivalent at diakinesis-metaphase I is reported.


Arteriography in ponies with Strongylus vulgaris arteritis. Radiographs of the aorta and abdominal arteries were obtained from a normal anesthetized pony following catheterization of a  femoral artery for nonselective, semiselective or selective arteriography. The arteries had smooth borders and regular diameters and the branches of the cranial mesenteric artery could be followed distally on the angiogram through to the smaller branches proximal to the bowel wall. Following arteriography, the pony walked normally and there were minimal alterations of the levels of serum muscle enzymes and blood lactate. The procedures for arteriography were repeated in three days. At that time the femoral artery was patent and satisfactory angiograms were obtained. Similiarly, radiographs were obtained from two ponies artificially infected with Strongylus vulgaris. The cranial msenteric artery and some of its branches, the right renal artery and segments of the aorta had irregular borders and were enlarged. Branches of the cranial mesenteric artery could not be followed distally because the flow of the contrast material was blocked. Following the above procedures, euthanasia of all ponies was expedited and the findings of arteritis, thrombosis and dilatation of arteries at necropsy compared favorably with interpretations from the radiographs. At least in the pony, arteriography can be a valuable research and diagnostic tool for the demonstration of lesions associated with verminous arteritis.


Susceptibility of Fusobacterium necrophorum to antimicrobials. Part I: as determined by the disc method. The susceptibility of 25 isolates of Fusobacterium necrophorum to 37 antimicrobials was tested using the disc method. F. necrophorum was susceptible to 15 antimicrobials, resistant to 12. To the remaining ten antimicrobials some isolates were completely resistant whereas others showed partial resistance.


The effect of temperature on growth and survival of Fusobacterium necrophorum isolated from bovine liver abscesses. The ability of Fusobacterium necrophorum to survive or grow in liquid nitrogen or at temperatures between -10 degrees and 59 degrees C was determined. The organism remained viable but did not grow in liquid nitrogen or between -10 degrees and 21 degrees C. It grew between 22 degrees and 43 degrees C. No isolate grew at temperatures above 43 degrees C and all three isolates survived for a minimum of 15 minutes and an average of 25 minutes at 59 degrees C. The optimum temperature for maximum growth was 37 degrees C. The organism survived in ampoules stored in liquid nitrogen for eight years. It survived in liver abscesses stored at -10 degrees C for five years and as cultures in screw capped tubes for three years.


The pathogenesis of leptospirosis I. Hemorrhages in experimental leptospirosis in guinea pigs. In experimental infections of guinea pigs with a virulent strain of Leptospira icterohaemorrhagiae widespread hemorrhages were observed. Thrombocytopenia, prolongation of prothrombin, thrombin, partial thromboplastin and coagulation times, decrease of plasma fibrinogen, factor V, factor VIII and the presence of fibrinogen degradation products were demonstrated. Treatment of infected guinea pigs with heparin prolonged life for two to three days. The histological observations revealed that the main lesion is a severe injury of the vasculature, mainly arteries, arterioles and capillaries. Most of the endothelial cells are affected or destroyed and the muscular fibers of arteries and arterioles are injured. With Martius-Scarlet-Blue, Weigert or Picro-Mallory stains it was demonstrated that the organization seen in the vessels is not all made of fibrin. The conclusion reached was that the hemorrhages observed in experimental leptospirosis in guines pigs are due to disseminated intravascular coagulation.


The pathogenisis of leptospirosis II. Jaundice in experimental leptospirosis in guinea pigs. Different mechanisms responsible for the appearance of jaundice in leptospirosis caused by Leptospira icterohaemorrhagiae in guinea pigs were discussed. Hepatocellular damage was demonstrated with the presence to a lesser extent of intrahepatic biliary obstruction. A massive destruction of extravascular red blood cells liberated by the hemorrhagic diathesis, appeared to be the main cause in the genesis of jaundice. The latter was inhibited following the neutralization of the reticuloendothelial system of guinea pigs by an irradiation before  the infection.


Toxic effects of butylated hydroxytoluene on rats. A study involving 96 weanling rats of both sexes was conducted to evaluate the effects of the antioxidant butylated hydroxytoluene on the plasma and liver lipid components. Comparative observations in the dietary content of butylated hydroxytoluene in ad libitum and underfed rats. A sex difference in the effects of butylated hydroxytoluene was noted. Butylated hydroxytoluene had a greater deleterious effect on the growth of the male than of the female rat, especially at the 0.5% dietary level (P less than 0.01). At this level, it also increased the relative weight of the liver (P less than 0.01) but had little effect on brain, heart and kidney in both sexes. The enlarged liver showed a marked elevation in the concentration of total lipids and of both total and esterified cholesterol. There were striking increases in the plasma total and esterified cholesterol and phospholipid levels in the butylated hydroxytoluene treated animals buy the triglycerides remained unaffected. The results obtained were more manifest in animals with restricted dietary intake. The changes observed in the lipid components occurred in parallel with the increasing amounts of the antioxidant in the diet. The effect of butylated hydroxytoluene on lipid metabolism is discussed.


Evaluation of a rapid method of determination of plasma fibrinogen in swine. An evaluation was made of a rapid semiautomated method for determining fibrinogen level in swine plasma. This method, referred to as thrombin time method or fibrometer method, is based on the principle that when thrombin is added to suitably diluted plasma, the time of clotting is linearly related to the fibrinogen concentration. The linear regression model for the standard curve prepared using swine plasma had an r value of 0.998. A comparison between the fibrometer and the Grannis methods done on 189 swine plasma samples showed good correlation between these two mehtods (r value 0.847). It was concluded that although the fibrometer method may not be as precise as the Grannis method, it would still be acceptable for clinical use in swine.


Effect of human chorionic gonadotropin on the transport of manganese and zinc and tissue uptake of radioactivity following subcutaneous administration of tritiated estrone in manganese deficient and nondeficient rabbits. Twenty-four eight month old virgin New Zealand doe rabbits were used in an experiment designed to study the effect of human chorionic gonadotropin on the transport of 54Mn and 65Zn in their tissues. Although human chorionic gonadotropin treatment did not result in any change in 65Zn transport, that of 54Mn was affected. In another experiment, the tissue uptake of tritiated estrone was studied in manganese deficient and nondeficient rabbits. There were no differences in radioactivity uptake between the two diets but the pattern of tissue uptake was different from other reports.


Recovery of Pasteurella hemolytica from aerosols at differing temperature and humidity. A Pasteurella hemolytica suspension with fetal calf serum was aerosolized in a standard system with ambient temperature of 30 or 2 degrees C and relative humidity conditions of 90 or 60%. The number of organisms sprayed in five minutes and the number recovered from one third of the aerosol during these five minutes was determined. Recoveries were influenced by temperature difference between aerosol and collecting fluid. Recoveries ranged between 0.059--0.94%.


Pulmonary lesions induced by Pasteurella hemolytica in cattle. Twelve four month old calves were inoculated intratracheally with a large dose of Pasteurella hemolytica and the lungs examined 18 hours, three days and seven days later. The gross and microscopic lesions were graded in each calf. The most extensive gross lesions were present at three days and were characteristic of a fibrinous pneumonia. Discrete areas of coagulation necrosis were present at three days and granulation tissue had formed around these by seven days. Characteristic swirly dark cells accumulated in alveoli and alveolar ducts and were observed from three days onwards. The gross and microscopic lesions were similar to those seen in field cases of pneumonic pasteurellosis.


The recovery of a Mycoplasma from Citellus richardsonii richardsonii (ground squirrel). Swabs from the upper respiratory tract, external genitalia and the eyes and portions of the lungs, spleen, kidney, liver and uteri of two ground squirrels were cultured for mycoplasma. The upper respiratory tracts of both animals were positive for mycoplasma as were the lungs, liver and spleen of one of the animals. Preliminary serological studies, growth inhibition test against 38 known antisera, growth precipitation against 15 antisera and fluorescent antibody technique with eight conjugates have, with the exception of a minor precipitin reaction against Mycoplasma bovirhinis, all been negative. The isolates are believed to be representative of either one or more new mycoplasma species.


Propagation of the rotavirus of neonatal calf diarrhea in fetal intestinal cell cultures. Bovine fetal intestinal cells were successfully propagated in monolayer cultures for up to 21 passages. Infection of these cells with the rotavirus of neonatal calf diarrhea resulted in a cytopathic effect that was more obvious than in infected bovine fetal kidney cells.


Inhibition of gas vesicle production in Microcyclus aquaticus by L-lysine. The timing and degree of gas vesicle production in Microcyclus aquaticus was affected by nutritional conditions. If 50 microng L-lysine/ml was added to a glucose-mineral salts medium (DM), the organism did not form gas vesicles. This effect was specific for L-lysine, as neither D-lysine nor meso-diaminopimelic acid prevented gas vesicle production. Cells grown in the presence of L-lysine did not contain any immunologically detectable gas vesicle protein, which indicates that L-lysine affects expression of the structural gene for the gas vesicle protein rather than assembly of the protein into gas vesicles. The addition of L-lysine to cultures in DM did not immediately decrease the rate of gas vesicle assembly, nor did the removal of cells from DM plus L-lysine to DM result in immediate gas vesicle production. Gas vesicle production was also affected by the addition of L-threonine or L-cysteine to culture media or by an increase in the medium's ionic strength. These results are discussed in relation to the aspartic acid pathway of amino acid biosynthesis and effects upon the intracellular L-lysine concentration.


The excretion of enterotoxin B from nongrowing cells of Staphylococcus aureus 4916. The physiological conditions for the excretion of staphylococcal enterotoxin B (SEB) by nongrowing cells have been determined. In general, SEB excretion appears to be best when amino acids serve as sources of carbon, nitrogen, and energy. Little toxin was produced in a nitrogen-free medium with glucose as the sole carbon source. Inhibitor studies have shown that most of the toxin excreted by nongrowing cells was the result of de novo protein synthesis. Optimum toxin excretion was also obtained under conditions of aeration, and at or near optimum growth temperature, those conditions at which the cells are metabolically and biosynthetically most active. Levels of cell-associated SEB decreased during toxin excretion. However, these levels of toxin could not account for the high levels of toxin released during excretion. Glucose and several other rapidly fermentable carbohydrates inhibited toxin excretion by as much as 80% under conditions of uncontrolled decrease in pH: however, when the pH was kept at either 6.2 or 7.5 a stimulation of toxin excretion was observed. Protoplast studies have suggested that SEB production does not take place in the absence of an intact cell wall.


Effects of exogenous fatty acids on growth and enterotoxin B formation by Staphylococcus aureus 14458 and its membrane mutant. Growth and enterotoxin B (SEB) formation by Staphylococcus aureus 14458 and its membrane mutant can be depressed or stimulated by addition of graded amounts of saturated or unsaturated fatty acid mixtures. Under some conditions depression of SEB formation is separable from growth inhibition. Individual fatty acids most active in altering growth and (or) SEB production have been identified. Small amounts of unsaturated fatty acid mixture not only antagonize some effects of saturated fatty acid mixtures, but also appear to potentiate inhibition of growth and SEB formation by the saturated fatty acid mixture. 2-Admantanone, a compound which increases cell membrane fluidity, strongly suppresses SEB formation while stimulating growth. The results are discussed in relation to possible effects of exogenous fatty acids on the composition of membrane phospholipids and attendant changes in SEB production.


Relationship of cytochrome content to the sensitivity of bacteria to NaCl on freezing and thawing. Eight species of bacteria representing rod, coccus, gram-positive, and gram-negative forms were tested for their sensitivity to sodium chloride during freezing and thawing. Six of the eight species tested were salt-sensitive, though to different degrees, while Lactobacillus casei and Streptococcus faecalis were resistant. Escherichia coli grown anaerobically exhibited only 38% of the salt sensitivity of aerobically grown cells. Analysis of cytochrome pigments in the organisms revealed that the six sensitive organisms all contained these pigments but in varying amounts, while the two resistant ones were devoid of them. Anaerobically grown E. coli contained 50% of the cytochromes of aerobically grown cells. A relationship between cytochrome content of the organisms and salt sensitivity during freezing and thawing was demonstrated with a correlation coefficient of 0.76 (P less than 0.05); the higher the cytochrome content, the more salt-sensitive the organism. This indicated that 58% of the salt sensitivity was due to the cytochrome content. Using a model organism E. coli, the effect of salt during freezing and thawing on the respiratory activity was examined. Freezing and thawing in water or saline decreased the respiration by whole cells of substrates expected to be NAD-linked while NADH-stimulated respiration was increased. In cell-free extracts derived from unfrozen cells or those frozen and thawed in water or saline, the respiration of ascorbate plus N,N,N',N'-tetramethyl-p-phenylenediamine (TMPD) was constant. The respiration of NADH, succinate, and lactate in cell-free extracts derived from cells frozen and thawed in saline was reduced compared with those extracts derived from unfrozen cells or cells frozen and thawed in water. Studies with E. coli showed that the decreased respiratory activity caused by disruptions in the electron-transport chain could not account for the salt sensitivity on freezing and thawing. More likely, salt sensitivity is related to the presence of bonds between cytochromes and other membrane components which are disrupted by sodium chloride on freezing and thawing. This would then result in loss of membrane integrity and function.


Response of soil microbiota to selected herbicide treatments. Recommended concentrations of paraquat alone and its combination with each of linuron, diuron, atrazine, simazine, and simazine plus diuron exerted little effect on total populations of bacteria, actinomycetes, and fungi in Fox sandy loam under laboratory and simulated field conditions in 66 and 77 days, respectively. Respiration of the total microbiota in soil suspension was afeected by the combinations as well as individual herbicides in various concentrations. Yet, the inhibition of the O2 uptake by any of these herbicides, including some extreme concentrations, was not permanent, indicating adaptation, or suppression of specific organisms. Only linuron in concentrations up to 20 microng/ml stimulated respiration of the soil.


Degradation of natural and Kraft lignins by the microflora of soil and water. The comparative rates of microbial degradation of 14C-lignin-labeled lignocelluloses and 14C-Kraft lignins were investigated using selected soil and water samples as sources of microorganisms. Natural lignocelluloses containing 14C primarily in their lignin components were prepared by feeding plants uniformly labeled L-[14C]phenylalanine through their cut stems. 14C-Kraft lignins were prepared by pulping lignin-labeled lignocelluloses. Rates of lignin biodegradation were determined by monitoring 14CO2 evolution from incubation mixtures over incubation periods of up to 1000 h. Observed rates of lignin degradation were slow in all cases. Kraft lignins appeared more resistant to microbial attack than natural lignins, even though they were decomposed more rapidly during the first 100-200 h of incubation. Similar degradation patterns were observed in both soil and water. Individual samples, however, varied greatly in their overall rates of degradation of either lignin type. A Kraft-lignin preparation was separated into a variety of molecular weight fractions by column chromatography on LH-20 Sephadex and the biodegradability of the different molecular weight fractions determined. The lower molecular weight fractions of the Kraft lignin were decomposed at a significantly faster rate by the microflora of soil than were the fractions of higher molecular weight.


The fine structure of Entomophthora apiculata and its penetration of Trichoplusia ni. The fine structure of conidia and immature resting spores of the entomogenous fungus Entomophthora apiculata is described. The two cell types contain comparable organelles and quantities of lipid, and possess a similar cell wall structure. The large quantity of stored lipid and numerous mitochondria in each cell type indicate a capacity for great metabolic activity. Numerous dense, microbody-like organelles were observed in conidia and resting spores, and their possible functions are discussed. Third instar larvae of the cabbage looper Trichopulsia ni were exposed to conidia of E. apiculata. Fungal germ tube formation and penetration of the host integument were observed. The germ tubes did not form appressoria and appeared to penetrate the epicuticle by enzymatic and physical means. After penetration of the epicuticle the germ tube often bifurcates, and expands as two or more digit-like projections parallel to the lamellae of the exocuticle. The hyphae gradually extend inward, cleaving the lamellae of cuticle, and eventually enter the host's body cavity.


Polymorphism of Malassezia furfur.

Polymorphism of Malassezia furfur. Alterations in the morphologic and physiologic characters of 11 isolates of Pityrosporum orbiculare were noted upon prolonged maintenance in pure culture. Successive subculturing of each isolate resulted in its progressive conversion from globose (P. orbiculare) through ovoid to cylindrical (P. ovale) form. Globose forms utilized neither olive oil nor Tween 20 as a sole carbon source, nor KNO3 as a sole source of nitrogen, while ovoid and cylindrical forms utilized both of these carbon sources, and one of four strains of the cylindrical form assimilated KNO3. These results suggest that P. orbiculare and P. ovale are stages in the complex developmental cycle of a single species (Malassezia furfur), but the three names should be preserved until the life cycle is more fully understood.


Effect of strain variation and growth phase of culture on dry weight and hexosamine content of cell wall layers of a marine pseudomonad. Two variants of marine pseudomonad B-16 (ATCC 19855) differing in  that one, variant 3, formed opaque colonies and the other, variant 7, formed translucent colonies were examined to determine if the variants differed in the amount and hexosamine content of their three outer cell wall layers. In both variants, the three outer layers of the cell wall, the loosely bound outer layer, the outer double-track layer, and the underlying (periplasmic space) layer contributed less to the dry weight of the cells when the cells were harvested in the stationary than in the logarithmic phase of growth. The hexosamine content of the layers of variant 3 increased dramatically as the cells went from the logarithmic to the stationary phase. The hexosamine content of the layers of variant 7 changed little by comparison. Thus cells of the variant which forms opaque colonies enrich the outer layers of their cell wall with hexosamine when grown to stationary phase.


Ribosomal ribonucleic acid cistron homologies among Hyphomicrobium and various other bacteria. The extent of hybrid formation between the ribosomal ribonucleic acid (r-RNA) of Hyphomicrobium strain B-522 and deoxyribonucleic acid (DNA) from bacteria of 21 different genera was examined. Three generalized groupings were formed. Group I (72-100%) consisted entirely of other strains of Hyphomicrobium. Representatives of the genera Rhodopseudomonas, Chromatium, Caulobacter, Prosthecomicrobium, Rhodomicrobium, Hyphomonas, and Hyphomicrobium made up group II (49-69%). The remaining Gram-negative, Gram-positive, and cell wall--less bacteria fell into group III (12-40%). The taxonomic implications of these results are discussed.


Value of the history in the office diagnosis of breast cancer. A review of the histories of 1059 patients with breast problems seen consecutively in office consultation revealed an incidence of breast cancer of 13%. Patients over 50 years of age or whose mother or sister had had breast cancer had a substantially greater likelihood of having breast cancer. The finding of the problem on routine examination, a family history of breast cancer in a relative other than the mother or a sister, or prominent breast pain or nipple discharge made the diagnosis of cancer less likely. Menstrual status, a history of previous benign disease, nulliparity, current hormone therapy and duration of symptoms did not help identify the patient likely to have breast cancer. Much time could be saved for both doctor and patient in taking the history from patients with breast disorders. Only the patient's age and the history of the mother and sisters with regard to breast cancer will help identify the "high-risk" patient. Other historical findings are either valueless or should be used to reassure these usually anxious women.


Early diagnosis of breast cancer: experience in a consultant breast clinic. Of 2839 women referred to a consultant breast clinic for clinical, mammographic and thermographic examination, 480 underwent biopsy and 126 were found to have cancer. Ten percent of the tumours were occult and were classified as very early biologic disease; they were identified by routine mammography in women whose breasts were clinically normal. Biopsy of solid mass lesions non-suspicious on mammography identified 20% of the cancers; half these lesions, classified as early biologic disease, were discovered by doctors at routine annual clinical breast examination, though the earliest cancers were detected by women who were confident and competent in monthly self-examination of the breasts. Biopsy of solid mass lesions suspicious on mammography identified 70% of the cancers; these were classified as late biologic disease. Skin or nipple dimpling or retraction was evident in two thirds of the patients; their lesions seemed to be later biologically than the lesions of the patients without clinical signs, and 75% had discovered the lesions themselves accidentally.


Breast cancer in northern Alberta: pilot study in computerized registration. Analysis of data from 643 breast cancer patients seen between 1971 and 1973 in northern Alberta was undertaken as a preliminary study leading towards a comprehensive breast registry. Age at first treatment and menopausal status were found to be related significantly to the clinical stage of the disease. Other data reported included age at menarche, lymph node involvement and methods of primary treatment. A decline in use of the radical mastectomy was noted. The comprehensive breast registry, which will be used to identify high-risk groups, assess treatment modalities, test hypotheses and generate ideas, has a high probability of success because of compulsory registration of new cases of breast cancer in Alberta and collection of data by the same four individuals.


Recent time-trends of age-specific death rates for breast cancer: Quebec and other provinces, 1965 through 1974. For the 10-year period 1965 through 1974 the age-specific death rates for cancer of the breast decreased among middle-aged women, especially at ages 40 to 49 years, in Quebec, the Maritimes and the Prairies but not in Ontario or British Columbia. In women under 35 years of age the mortality generally increased, while in women aged 60 to 64 years there was little change except in the Prairies, where the rate increased. It seems probable that the trends reflect changes in incidence rather than in case-fatality. Some, but not all, of the pattern could be explained by changes in fertility over the past 50 years.


Urinary screening program to detect renal disease in preschool and kindergarten children. In an attempt to detect major structural problems of the urinary tract in the early stages 12 006 preschool and kindergarten children (aged 2 to 6 years) were screened for urinary tract infection. Two cases of renal scarring--unilateral in one child and bilateral in the other--were found. It was often difficult to obtain a urine sample and many cultures yielded false-positive results. In terms of cost and effort expended in relation to the low yield of major nephrologic problems, there appears to be no justification at present for routine screening for urinary tract infection in this age group.


Diagnostic accuracy of cerebral angiography and computerized transaxial tomography. Computer tomography (CT) of the brain has become widely accepted as an accurate method of studying a variety of intracranial diseases. In a prospective controlled study one group of radiologists interpreted cerebral angiograms and another interpreted CT studies undertaken in the same patients. The overall rates of diagnostic accuracy were similar (81 and 84% for angiography and CT, respectively), albeit less than reported in the literature, and thus support the contention that CT scanning should be available as the initial neuroradiologic examination whenever possible.


Operating-room venting of trace concentrations of inhalation anesthetic agents. Operating-room personnel exposed over a long period to trace concentrations of anesthetic gases may acquire both organic disturbances and impairment of cerebral function, though this has not been proven. However, the dangers of miscalculations due to disturbances of cerebral function and the fact that all working personnel should be breathing unpolluted air are sufficient indications to make scavenging of anesthetic gases mandatory. Scavenging has been carried out in many hospitals. At Vancouver General Hospital venting of the gases has decreased the nitrous oxide pollution to what is considered an acceptable level.


Myocardial abscess complicating healed myocardial infarction. An isolated myocardial abscess due to Bacteroides fragilis developed in the scar of a myocardial infarction. Fever, chills and signs of pericarditis were the main clinical features. Mild enteritis 1 week prior to the onset of symptoms related to the abscess was the most likely cause of the bacteremia. The diagnosis was established at thoracotomy, performed because of cardiac tamponade. Thirteen other cases of isolated bacterial myocardial abscess accompanying myocardial infarction have been reported, but all the infarctions were recent. Surgical resection for a suspected myocardial abscess should be considered in view of the high mortality, largely from cardiac rupture.


Thrombosis of Björk-Shiley aortic valve prosthesis: report of three cases. Thrombotic malfunction of a Björk-Shiley aortic valve prosthesis occurred in three patients 6 to 16 months postoperatively. None of the patients had been taking anticoagulants. Although the presentation was acute, prodromal symptoms could be identified retrospectively in two of the patients. Two patients survived thrombectomy. Postoperative anticoagulant therapy is recommended in patients with these prostheses despite factors that may make such therapy riskier in specific patients. Attention to the character of murmurs and of the closure sound of the prosthetic valve must be part of the routine follow-up. In the emergency situation, when delay must be avoided, catheterization and angiography are unnecessary. The operative approach consists of complete thrombectomy without replacement of the valve or any of its components unless there is obvious periprosthetic leak or prosthetic wear.


Plasma lipids and lipoprotein patterns in angiographically graded atherosclerosis of the legs and in coronary heart disease. The prevalence and type of plasma lipoprotein abnormalities were determined in 114 French-Canadian patients with angiographically proven peripheral vascular disease (PVD). The severity of atherosclerosis was positively correlated with plasma triglyceride concentration, especially in the younger patients (r = 0.29, P less than 0.05), and (not significantly) with plasma cholesterol concentration. Of the risk factors believed to predispose individuals to atherosclerosis, cigarette smoking was the most frequently found in the PVD patients (72.8%), especially among the men. Combination of two or more risk factors was the rule. Findings were compared with those in 114 patients who had undergone coronary angiography for suspected coronary heart disease (CHD). The CHD patients were, on average, younger by 10 years. Hyperlipidemia was present in 58.8% of CHD patients, compared with 43.9% of PVD patients. A far higher proportion of CHD patients showed the type II plasma lipoprotein pattern (24.6% v. 7.9%), although the type IV pattern was more common in both groups (31.6% and 28.9%, respectively). A high proportion of all patients (56.1% with PVD and 41.2% with CHD) showed a normal lipoprotein pattern on paper electrophoresis.


Sexual activity after myocardial infarction. Questionnaires on sexual activity were completed by 161 patients attending an exercise-centred rehabilitation program an average of some 3 years after a myocardial infarction. In almost half the group, sexual activity was unchanged or increased compared with the period before the infarction. In the remainder it was reduced; this group included 29 men who had adopted a more passive sexual role and 26 who were now having angina or ventricular premature beats during intercourse. Although the patients with diminished activity could not be distinguished by means of formal personality test, questionnaires completed by their wives suggested that they were less willing to assume responsibility, had increased difficulty in adjusting to life at home and at work and were more neurotic and depressed than those with normal or increased activity. Furthermore, those with decreased sexual activity had a poorer response to training in terms of attendance, final average jogging distance and gains in physiologic status. Since the frequency of angina and ventricular premature beats was less during intercourse than during standard laboratory exercise, it was concluded that normal sexual relations carry no special risk for the average postcoronary patient; indeed, by enhancing self-esteem and encouraging effective participation in an exercise programm, acceptance of normal sexual activity may improve the prognosis.


Surgery and anesthesia in Ontario.

Surgery and anesthesia in Ontario. Operative and case-fatality rates in Ontario for eight elective (discretionary) and seven nonelective (nondiscretionary) operations and the proportions of these operations and their anesthetic procedures performed by general practitioners were calculated. Cholecystectomy increased in frequency 32% from 1968 through 1973, tonsillectomy and adenoidectomy decreased 37%, and hysterectomy increased 41%. Except for colectomy the rates for nonelective operations changed only slightly over the 6 years. Case-fatality rates (hospital deaths per 10000 operations) for the discretionary operations in 1973 were as follows: extraction of lens, 23.1; tonsillectomy and adenoidectomy, 0.4 (2 deaths among 52938 operations); varicose vein stripping, 6.1; nonrecurrent inguinal herniorrhaphy, 21.9; cholecystectomy, 61.0; hemorrhoidectomy, 9.8; prostatectomy, 115.9; and hysterectomy, 9.6. In 1973 general practitioners did 32% of tonsillectomies and adenoidectomies (61% in 1971), 10 to 20% of inguinal herniorrhaphies, hemorrhoidectomies and appendectomies and 6% or less of the other operations. However, they performed 35% or more of the anesthetic procedures for these four operations as well as for varicose vein stripping, cholecystectomy and hysterectomy. Rates of general-practice surgery and anesthesia in an urban centre in Ontario were substantially less than those for the province as a whole.


Patterns of practice in internal medicine in Ontario. To determine the feasibility of wholly referral practice in internal medicine within a prepaid health service, the practice profiles of 694 internists in metropolitan, nonmetropolitan urban, and rural areas of Ontario were delineated by analysis of data from questionnaires and health-insurance billing. The questionnaire showed that two thirds of internists, chiefly younger practitioners, confined themselves to a referral consultant practice; the other one third included primary care. Subspecialists practised predominantly in metropolitan areas; most general internists in such areas provided primary care, whereas most general internists elsewhere had an entirely referral practice. This pattern of practice is greatly different from that in the United States but probably similar to that in other provinces in Canada. Extension of wholly referral practice to all internists in Ontario appears feasible, provided the numbers entering residency training are controlled. The present Ontario curricula for internal medicine and its subspecialties appear suitable for such a pattern of practice.


Male pseudohermaphroditism: diagnosis in cell culture. Testicular feminization is a classic form of complete male pseudohermaphroditism. The individuals have a normal XY karyotype but unambiguously female external genitalia. They have congenital complete insensitivity to androgen due to an X-linked mutation. In four patients (from tow families with several affected members) with the typical phenotype of testicular feminization, a severe deficit of specific androgen-binding activity was detected in cultured fibroblasts from labium majus skin. Measurement of this activity in genital skin fibroblasts improves the differential diagnosis in patients with complete or imcomplete male pseudohermaphroditism before puberty.


[Diphtheria epidemic occurring on the North Shore of the St. Lawrence River in the fall of 1974]. An outbreak of diphtheria occurred on the North Shore of the St. Lawrence River at the beginning of September 1974. It started with the death of an 18-year-old forest worker Sept. 5, spread over a vast area of the North Shore and lasted until the end of October that year. Eleven strains of toxigenic Corynebacterium diphtheriae intermedium, type K were isolated. Eleven of the 12 patients had characteristic diphtheritic pharyngitis with pseudomembranes. Preventive measures, set forth immediately after the third case was declared, included the following: (a) daily surveillance of all contacts, (b) isolation or preventive hospitalization of persons with all types of pharyngitis, (c) mass vaccination of all susceptible persons and (d) search for healthy carriers of the germ. No strains of toxigenic C. diptheriae were isolated from patients preventively hospitalized or from the 1235 individuals among whom carriers were sought. Among the main characteristics of this epidemic, the mean age of the patients (17 years), their mobility and their habits are factors that could have made it almost uncontrollable. It is also remarkable that this outbreak occurred in such a scattered population of adolescents, in 82% of whom the Schick test was negative.


Nutrient intake and meal patterns of Micmac indian and Caucasian women in Shubenacadie, NS. North American Indians have a higher morbidity from gallbladder disease, diabetes mellitus and obesity than other North Americans; this may result from their food intake. Nutrient intake and meal patterns were compared in 120 Micmac Indian and 115 Caucasian women in Shubenacadie, NS. Findings were compared with the Canadian Dietary Standard (CDS) and the Nutrition Canada national and Indian survey reports. The diet of Indian women had higher carbohydrate, lower protein and lower fibre content than that of Caucasian women, who derived a higher percentage of energy from protein and had a higher intake of vitamin A, niacin and ascorbic acid. Overnight fast was longer among Indian women. A high percentage of all women studied reported diets that did not reach the CDS for total energy intake in kilocalories or for calcium, iron, vitamin A, thiamin or riboflavin.


[Potomania: re-evaluation of the diagnostic tests and unusual presentation with hydronephrosis and megabladder]. Three cases of compulsive polydipsia previously diagnosed as diabetes insipidus are presented. Abnormally dilated bladder and pyelocalyceal systems were accompanying features, as previously described for diabetes insipidus, particularly of renal orign. Results of the hypertonic saline (Hickey-Hare) test were positive in only one case. Results of restriction of liquids followed by intravenous injection of vasopressin (Miller test) favoured a diagnosis of complete diabetes insipidus. These two tests cannot, therefore, exclude compulsive polydipsia. The features suggesting a diagnosis of compulsive water drinking are low plasma osmolality, a decrease in 24-hour urine output following water restriction, and abnormal behaviour. The diagnosis is confirmed by an 18-hour dehydration test done after gradual fluid restriction, which favours partial restoration of the papillary osmotic gradient.


Recurrent malignant melanoma: effect of adjuvant immunotherapy on survival. Twenty-nine patients referred consecutively to a cancer clinic because of recurrent metastatic malignant melanoma were given 5 mg of Connaught Laboratories bacillus Calmette-Guérin (BCG) by multiple cutaneous puncture at weekly and later at monthly intervals. Eight were also treated with autologous tumour vaccine and three with intralesional BCG. This group was compared with a retrospective control group of 54 patients treated with surgery and radiotherapy alone after recurrence. Prognostic features such as site of primary and of first metastasis, disease-free interval, age and sex were similar in the two groups. However, the median survival from the time of first recurrence was 12 months in the control group but 21 months in the BCG-treated group. The major improvement was in patients with disease limited to the regional lymph nodes: the median survival was 16 months in the control group but over 32 months in the BCG-treated group. Autologous tumour vaccine appeared to have no effect on survival. Serial testing of immunocompetence did not offer any prognostic advantage, although the results of some tests correleated well with extent of disease.


Wilson's disease: a common liver disorder? In two sibships 7 of 24 siblings were homozygous for Wilson's disease. In family A, the largest kindred of this recessively inherited disease thus far reported, the proband presented with chronic active hepatitis, one sibling died of cirrhosis, a second had clinical evidence of chronic liver disease and two others had biochemical and histologic changes in liver biopsy specimens. In family B the proband had cirrhosis and portal hypertension and one sibling had biochemical and histologic evidence of liver disease. All six living patients had low serum concentrations of ceruloplasmin and copper and a high 24-hour urinary excretion of copper, which was greatly increased by administration of D-penicillamine. None showed neurologic abnormalities and only one had Kayser-Fleischer rings (detectable only by slit-lamp examination). Each patient had an erythrocyte sedimentation rate (ESR) of 8 mm/h or less. After 3 and 2 years, respectively, of D-penicillamine therapy the conditions of the two probands had improved. Liver function became normal in three siblings, and no abnormalities developed in the remaining one. Thus, since Wilson's disease may present with chronic active hepatitis or cirrhosis with a normal ESR and without ocular or neurologic signs, it may be a more common cause of liver disease in young people than has been appreciated.


Immunoblastic lymphadenopathy: case report and literature review. A patient with immunoblastic lymphadenopathy (IL) had an unusual course of illness, with frequent episodes, over a 20-month period, of chills, fever, abdominal pain, hepatosplenomegaly and weight loss. The episodes were short-lived and many resolved spontaneously. Eventually generalized lymphadenopathy and profound monoclonal IgG gammopathy developed, with atypical mononuclear cells in the peripheral blood and increased numbers of plasmacytoid cells in the bone marrow. Lymph node biopsy revealed the morphologic triad typical of IL: proliferation immunoblasts, proliferation of small blood vessels and the deposit of an amorphous acidophillic material in the vascular walls and the interstitium. Up to October 1976 110 cases had been reported of this disorder, first described 3 years ago, which indicates that IL is not rare. Remissions have occurred spontaneously and after steroid therapy or chemotherapy or both. However, death has been reported in almost 50% of the cases, and the best approach to therapy remains to be determined.


Recent changes in the emotional reactions of therapeutic aboriton applicants. The emotional status of one hundred women applying for therapeutic abortions during 1967/68 was compared with that of 100 more recent applicants in 1975. The Minnesota Multiphasic Personality Inventory of the two groups reveals a significant reduction in psychopathology amongst the more recent applicants. This difference remains when group differences in age are controlled, and applies when married and single subgroups are considered separately. These results are interpreted as suggesting that the generally more liberal social atmosphere surrounding present-day abortions is reducing psychological stress among women undergoing this procedure.


A brief scale for predicting rehospitalization of former psychiatric patients. Community adjustment of former psychiatric patients has been found to relate highly to the likelihood of rehospitalization and community tenure. The present study examined the ability of a community adjustment scale and various other patient characteristics to predict rehospitalization. Multiple regression analysis using rehospitalization as the dependent variable identified thirteen items including twelve from the community adjustment scale, which combined to provide a highly accurate prediction. The brief scale (13 items) which is now being cross-validated is potentially a useful tool for clinical evaluation and planning of follow-up series to former patients.


In vitro induction of aryl hydrocarbon hydroxylase in human pulmonary alveolar macrophages by benzanthracene. Aryl hydrocarbon hydroxylase (AHH) was induced in human pulmonary alveolar macrophages (PAMs) cultured in the presence of benzanthracene. Time and dose--response curves were established for in vitro induction of this enzyme system in PAMs. In addition, a positive correlation was noted between the level of AHH activity in freshly lavaged PAMs and the in vitro inducibility of the enyzme in these cells from either nonsmokers or cigarette smokers. Measurements of the inducibility of AHH in cultured human PAMs provide an experimental system suitable for studying the mechanisms responsible for the initiation of pulmonary carcinogenesis.


Short-term carcinogen-induced changes in composition of rat liver chromatin protein. Changes in the composition of rat liver chromatin protein were detected by electrophoretic analysis 4 h after a single injection of 10-30 mg/kg body weight dimethylnitrosamine. Non-histone bands were reduced in staining intensity and increases in all F2 histone subfractions were observed. The staining intensity of F1 and F3 histone was unchanged throughout the experiment. By 24 h after administration of a non-necrotizing dose of dimethylnitrosamine, the proportion of chromatin proteins, when compared to controls, was marked by an increase in non-histones and decreased amounts of F2 histone subfractions. Slight differences between treated and control were evident at 48 h, suggesting that at least this interval is required for recovery from in vivo methylation.


Measurement of 'unscheduled' DNA synthesis in HeLa cells by liquid scintillation counting after carcinogen treatment. HeLa cells, conditioned in an arginine-deficient medium to reduce DNA S-phase synthesis, were treated with one of four ultimate carcinogens (MNNG, BrMBA, N-acetoxy AAF and EMS) and one precarcinogen, AFB1. All treated cells preferentially incorporated [3H] thymidine as a result of DNA repair monitored by liquid scintillation counting of the extracted DNA. The cells showed some capacity to activate AFB1, but repair synthesis was much increased if a rat liver mixed function oxidase preparation was also present. At equimolar concentrations the various carcinogens stimulated different amounts of DNA repair; this variation was not proportional to the carcinogenic potency of the chemicals tested. Reasons for this are discussed as is the use of this technique as a screen for chemical carcinogens.


False-positive and false-negative rates for carcinogenicity screens. The implementation of a number of chemical carcinogen screening programs has been accompanied by the observation that some screens might have high false-positive error rates. With designs presently used at the National Cancer Institute and historical spontaneous tumor rates based upon control animals in previous experiments, we compute upper bounds on the false-positive error rates for several screening strategies. False-positive results are much less likely to occur at tissue sites with low spontaneous tumor rates; hence the site at which a significant tumor increase occurs is important. There is danger in relying solely upon the finding of statistical significance without incorporating biological knowledge and corroborative evidence such as the presence of a dose-response relationship or experimentally consistent results in different species or sexes. A report by the National Cancer Institute Carcinogenesis Program demonstrates these concepts.


Therapeutic effects of 9-beta-D-arabinofuranosyladenine and 2'-deoxycoformycin combinations on intracerebral leukemia. Drug combinations of 9-beta-D-arabinofuranosyladenine and 2'-deoxycoformycin were active in the therapy of mice with intracerebral implants of the L1210 tumor. In in vivo mouse brain adenosine deaminase studies, inhibition of 9-beta-D-arabinofuranosyladenine deamination for periods of up to 24 hr was found after a single i.p. dose of 0.002 mmole/kg.


Human lactic dehydrogenase as a marker for human tumor cells grown in athymic mice. Human tumors implanted s.c. into athymic mice released lactic dehydrogenase (LDH) isoenzymes unique to human tissue. These isoenzymes were readily identified and quantitated in mouse plasma. When injected into mice i.p. or i.v., human LDH isoenzymes were rapidly cleared from the blood circulation, decreasing to within 10% of the initial value in 12 hr. When human tumor cell lines (HEp-2 and T-24) were injected i.v. into heterozygote or athymic mice, they released LDH isoenzymes over a 24-hr period. When these cells were injected by the i.p. route, they released the isoenzymes over the 4-day period studied. Solid tumors of HEp-2, T-24, and SW-733 cells s.c. implanted continuously released amounts of LDH that were directly related to tumor mass. Therefore, the measurement of plasma levels of human LDH isoenzymes in athymic mice is a useful parameter for detecting the presence and growth of human tumors in these animals. Since the bulk of the released LDH is assumed to derive from injured or destroyed human tumor cells, the assay for these isoenzymes should provide a useful marker for determining the effectiveness of experimental antitumor therapy in athymic mice.


1,10-Phenanthroline inhibition of lymphoblast cell cycle. The effects of the metal-chelating agent, 1,10-phenanthroline (OP), on the cell cycle progression of CCRF-CEM lymphoblasts has been studied by flow microfluorometry. Lymphoblasts were incubated with 2,3-dihydro-1H-imidazo[1,2-b]pyrazole in order to block them in G1-early S. The block was then reversed by incubating the cells in fresh media. Within 2 to 4 hr, approximately 90% of the cells were in S phase and, by 6 hr, approximately 80% were in late S. Aliquots of these latter cells then were incubated with podophyllotoxin to block them in G2-M. These cells divided within 4 hr of reversal of the podophyllotoxin block. Lymphoblast populations in G1-early S, mid-S, or G2-M were then incubated with 4 micronM OP. OP blocked entry of G1 cells into S as well as progression through S but had no effect on progression from G2-M to G1. The OP effects were reversed by addition of Zn2+, Cu2+, or Fe2+ or by dilution of the chelating agent in the growth media. Incubation of CCRF-CEM lymphoblasts with 1,7-phenanthroline, a nonchelating analog of OP, did not affect the cell cycle. The data indicate that OP reversibly blocks progression of cells from G1 to S and through S by chelation of metals involved in processes essential for those cell cycle events.


Hormone-dependent neoplasms of the canine perianal gland. The epidemiological features of 472 dogs with microscopically confirmed neoplasms of the perianal gland are described. These general characteristics suggest etiological factors similar to those responsible for hormone-related neoplasms occurring in human beings. Perianal gland tumors appear to be androgen dependent. Male dogs show a 5.6-fold-increased risk compared with females; endogenous estrogens offer protection and the use of estrogenic hormones is conventional therapy for the benign lesion. Both sexes of the cocker spaniel breed show excessively high risk, suggesting that this dog family may be a model for genetic studies that could be relevant to familial aggregations of hormone-related tumors in men and women. Adrenocortical hormones may play a role in the development of the tumor in female dogs. Research into alterations of the biochemical pathways of steroidogenesis in affected female dogs may provide clues to similar conditions in humans.


Selective incorporation of L-3,4-dihydroxyphenylalanine by S-91 Cloudman melanoma in vitro. The incorporation of precursors of the biopigment melanin into melanotic and amelanotic S-91 Cloudman melanoma, mouse fibroblast L-929, and Chinese hamster ovary cells was studied. Tyrosine did not selectively accumulate in pigmented cells compared to that in nonpigmented control cells. Inhibition of protein synthesis with cycloheximide provided an estimate of the partition of tyrosine between protein (95%) and pigment biosynthesis (5%). L-3,4-Dihydroxyphenylalanine, a more proximal precursor of melanin, was selectively incorporated into pigmented cells up to 60 times that of control lines. alpha-Melanocyte-stimulating hormone and theophylline, agents that enhance pigmentation, further increased the incorporation of L-3,4-dihydroxyphenylalanine into melanocytic cells. A unique property of melanoma cells thereby has been defined that may permit a selective chemotherapeutic and diagnostic approach.


Differential cytotoxicity between transformed and normal human cells with combinations of aminonucleoside and hydroxyurea. Normal human WI-38 cells can be protected from killing by hydroxyurea if proliferation is arrested during drug treatment. This protection was demonstrated both in cells arrested by density-dependent inhibition and by 3'-amino-3'deoxy-N6,N6-dimethyladenosine (puromycin aminonucleoside). In contrast, VA-13 cells (a simian virus 40-transformed clone of WI-38) were not arrested under these conditions, and continued to be sensitive to hydroxyurea. These results suggest that a search for agents that selectively and reversibly inhibit normal cycling human cells might lead to an enhancement of differential tumor toxicity.


Effect of type and amount of dietary fat and 1,2-dimethylhydrazine on biliary bile acids, fecal bile acids, and neutral sterols in rats. The effect of type (corn oil or lard) and quantity (5 or 20%) of dietary fat and 1,2-dimethylhydrazine (DMH) on the composition of biliary bile acids, fecal bile acids, and neutral sterols was studied in rats exposed to a given regimen for two generations prior to s.c. treatment with DMH for 20 weeks. Biliary excretion of total bile acids as well as cholic acid, beta-muricholic acid, ursodeoxycholic acid, and deoxycholic acid was higher in rats fed a diet containing 20% corn oil or lard than it was in rats fed diets containing 5% corn oil or lard. Treatment of animals with DMH produced an increase in biliary total bile acids, cholic acid, hyodeoxycholic acid, and deoxycholic acid irrespective of diets. High-fat (corn oil or lard at 20% level) intake was associated with an increased excretion of fecal neutral sterols and bile acids. The excretion of deoxycholic acid, lithocholic acid, and 12-ketolithocholic acid was increased in rats fed high-fat diets. The source of fat had no major influence on the excretory pattern of cholesterol metabolites and bile acids. DMH-treated animals excreted higher levels of fecal coprostanol, coprostanone, deoxycholic acid, lithocholic acid, and 12-ketolithocholic acid than did controls.