Antiviral activities of 4'-(9-acridinylamino)-methanesulfon-M-aniside (SN11841). SN11841 [4'-(9-acridinylamino)-methanesulfon-m-aniside] is an antitumor compound discovered by B.F. Cain. The LD50 for BALB/c mice with single intraperitoneal dosage is approximately 25 mg/kg. RLV-(Rauscher leukemia virus)-induced splenomegaly, a disease indicator in BALB/c mice, is inhibited at SN11841 doses not causing acute mortality. The life span of RLV-infected mice increases at some SN11841 doses. SN11841 does not have direct, or virolytic effects on RLV under conditions approximating those of antiviral effectiveness. SN11841 is cytotoxic for cells in tissue culture, as measured by inhibition of growth rate or vital dye uptake. At nontoxic concentrations SN11841 has no effect on RLV infectivity for murine cells, as determined by XC-cell induced syncytium formation. SN11841 has antiviral activity against vaccinia virus in tissue culture but is inactive against herpes simplex (Type 1), vesicular stomatitis, encephalomyocarditis, or reoviruses. SN11841 apparently does not act by inducing interferon. SN11841 is chemically labile, particularly in the presence of sulfhydryl compounds, but the degradation products resulting from prolonged storage in media are neither cytotoxic nor antiviral.


Selective inhibition of RNA tumor virus replication in vitro and evaluation of candidate antiviral agents in vivo. A limited number of biologically active materials were examined for their relative ability to selectively inhibit the replication of Gross or Rauscher murine leukemia virus (MLV) in Swiss mouse embryo cells by means of the UV-XC plaque-reduction assay. Among the compounds demonstrating significant antiviral activity against Gross MLV in vitro were 1-(4-fluorobenzyloxy) adenosine (FBAR), polyadenylic acid [poly(A)], the carbocyclic analogue of 6-methylthiopurine ribonucleoside (C-MeMPR), 3-(2,4-dinitrophenylhydrazonemethyl)rifamycin SV (AF/DNFI), and phosphonoacetic acid (PAA). Five compounds that exhibited significant antiviral activity against MLV in vitro were tested for similar activity against Rauscher MLV in vivo. Three of these selected compounds, pyrazofurin (pyrazomycin), ribavirin (Virazole), and 9-beta-D-arabinofuranosyladenine (ara-A), produced a significant (50%-100%) inhibition of virus-induced splenomegaly development in mice, whereas the other two candidate inhibitors, 3-deazauridine (deazaUR) and rifamycin SV, the other two candidate inhibitors, 3-deazauridine (deazaUR) and rifamycin SV, failed to demonstrate any in vivo activity in this 21-day leukemogenesis assay. The administration of an inhibitor of adenosine deaminase (Co-vidarabine) in combination with ara-A resulted in an enhanced antiviral response in both infected cell cultures and animals. Co-vidarabine also increased the potency of ara-AMP against Gross MLV in vitro, indicating the probable dephosphorylation of the compound to ara-A and its subsequent deamination to ara-H in this system.


Relative potencies of anti-herpes compounds. Assessment of the relative potencies of compounds that inhibit the multiplication of herpesvirus is rendered difficult by the fact that they have been investigated by different workers who were not using comparable test systems. The relative and absolute potencies of idoxuridine, cytarabine, vidarabine, trifluorothymidine, and ara-DAP have therefore been evaluated by plaque inhibition, plaque reduction, and yield reduction tests, the most satisfactory dose-response lines being obtained by plaque reduction. The results obtained for five strains of type 1 and five of type 2 herpesvirus indicated that cytarabine was the most active compound, followed by idoxuridine and trifluorothymidine; vidarabine and ara-DAP were found to be the least active compounds. From comparisons of ED50 values derived from the dose-response lines it was found that the greater sensitivity of type 1 strains reported in the literature could only be confirmed with idoxuridine, since considerable overlaps in type sensitivity were observed with the other compounds.


Cutaneous herpes simplex virus infection of guinea pigs as a model for antiviral chemotherapy. The kinetics of Herpesvirus hominis (Type 1) replication and lesion development in guinea pig skin were determined. The data indicate that lesion scores did not always reflect virus content. Virus replication was detected prior to appearance of lesions and maximum virus content preceded maximum lesion score. Lesions resolved slowly while virus content declined rapidly to an undetectable level. The utility of the guinea pig skin-herpesvirus model for the evaluation of ara-A and kethoxal was studied. Ara-A treatment at three dose levels suppressed lesion development and at the two highest dose levels lesion development was delayed. Lesion virus content, when determined during the period of maximum virus replication, was not affected by treatment. Kethoxal markedly suppressed lesion development and virus growth. Aspects of this experimental model typify cutaneous herpes simplex disease of man. Studies designed to further assess its utility for evaluating antiviral drugs seem warranted.


Effect of an interferon inducer, 9-methylstreptimidone, on influenza virus infection in mice. The antiviral effect of 9-MS was examined in mice infected with mouse-adapted influenza A2 (H2N2) virus. Either a single or a continuous prophylactic administration of 9-MS protected mice from virus infection, and comparison of the minimal effective dose with the lethal dose gave a therapeutic index of approximately 60. When the treatment was started after infection, however, no antiviral effect was demonstrated. A potent virus-inhibitory factor was detected in the lung and serum after a single intraperitoneal administration of 9-MS in uninfected mice, and on the basis of chemical characteristics of this inhibitory factor, it was assumed to be an interferon. These results suggest that the protective activity of the antibiotic in mice is due to interferon induction.


Acceleration of scrapie in mice by target-organ treatment with interferon inducers. Interferon inducers were used in the target-organ treatment of scrapie in mice. Intracerebral treatments began 24 hr prior to intracerebral inoculation of 10(4.8) LD50 of the Chandler strain of scrapie agent. The treatments included 30 and 0.3 microgram poly(I:C) given weekly 9 times, 45 microgram statolon given biweekly 7 times, or 1.5 HA units of Sendai virus given biweekly 6 times. All treatments except the lower dose of poly(I:C) accelerated death in scrapie-affected mice. Compared to saline-treated control groups, 30 microgram poly(I:C), given weekly, shortened the mean survival time 13.5 days. Groups treated with statolon or Sendai virus had their mean survival times shortened 18.5 and 21.7 days, respectively. Infected mice were also evaluated for signs of disease at approximately weekly intervals using a numerical scoring method. Acceleration was also apparent using this parameter of disease. When treatment occurred only once, Sendai virus was the only inducer to significantly shorten the survival of mice.


De novo cell-free synthesis of human interferon. Biologically active human interferon was synthesized de novo in a cell-free mouse extract stimulated with messenger RNA from induced human fibroblasts. The identity of the antiviral activity as human interferon was demonstrated by its antigenic and species specificity. Some characteristics of the cell-free synthesis were described.


Multidisciplinary collaboration in fieldwork: Australian studies. The Australian situation offers special insights for cross-cultural psychiatric research. The two cultures that "crossed" in Australia were diametrically opposed in their characteristics. Suffering, which is considered to be the raison d'être of cross-cultural psychiatry, became pandemic among Aborigines, not only because the invading society was ruthlessly aggressive, but also because the invaded society did not have the social institutions and modal personality patterns enabling it to adapt to the introduced culture. It is suggested that no applied science makes more demands of more scientific disciplines than does cross-cultural psychiatry. Psychiatry itself is a multidisciplinary science. The amount of information needed by the cross-cultural extension of psychiatry is further expanded. Only a multidisciplinary approach can furnish the necessary level of information. An outline is given of multidisciplinary field work in Australia, indicating advantages and difficulties inherent in it. Attention is drawn to literature in which details of the results may be found. The Australian work leads to the conclusion that if the relief of suffering is the aim then greater involvement is needed in cross-cultural psychiatry from the culture that has been "crossed".


Environmental significance of fin erosion in southern California demersal fishes. The Dover sole was the species most often affected with eroded fins. Prevalence of the disease was highest on the Palos Verdes shelf, the site of a major municipal waste water discharge. Fin lesions in this species were characterized by a minimal inflammatory response and by the absence of associated microorganisms. The fins most frequently affected were those most often in contact with bottom sediments. Diseased specimens from the shelf had higher levels of total DDT and a tendency toward higher levels of total PCB in muscle tissue and a greater liver to body weight ratio than did unaffected specimens from the same area. Laboratory exposure of M. pacificus to contaminated sediments from the shelf resulted in the development of fin erosion. Chlorinated hydrocarbon levels and liver weight to body weight ratios in the exposed fish approached those measured in fish from the shelf. These studies suggest that fin erosion in M. pacificus is caused by exposure to contaminated sediments and that the role of chlorinated hydrocarbons should be tested directly in future experiments.


Temperature-dependent growth and regression of epidermal tumors in the european eel (Anguilla anguilla L.). The population of eels in the Elbe estuary showed a high rate of affliction with epidermal papillomas. Distinct seasonal fluctuations were observed in the frequency of occurrence and tumor size. In spring and autumn, the frequency was low, and the tumors were relatively small. In summer, the tumors reached a maximum in both frequency and size. A distinct influence of water temperature on tumor growth was demonstrated experimentally. Summer temperatures of 15--22 degrees C caused very rapid growth. In the field and in the laboratory, the tumors exhibited a fourfold increase in average volume within 3 months. These fast-growing neoplasms had certain relatively uniform histologic features. The tumor cells were separated by wide intercellular spaces. The basal layer was composed of tall columnar cells, while the surface layer was composed of slightly flattened cells. Winter water temperatures (5--10 degrees C) inhibited tumor growth and even caused tumor regression. In 3 months, the papillomas shrank to half of their initial size. Histologic and ultrastructural examinations revealed signs of tissue degeneration: necrobiotic processes in the epidermal region, cellular and nuclear polymorphisms, dissolution of membranes, loss of cell integrity, and loosening and reduction in size of the basal cell layer.


Tissue lesions of tiger salamanders (Ambystoma tigrinum): relationship to sewage effluents. A population of facultative neotenous tiger salamanders (A. tigrinum) inhabiting a sewage lagoon at Reese AFB, Hurlwood, Texas, was found to have an exceptionally high rate of spontaneous tissue lesions. The population is composed of an estimated 28,000 large, reproductively mature larvae that are restricted to the lagoon. Only about 17% of the population metamorphoses normally. In contrast, tiger salamanders from uncontaminated lagoons in the same general vicinity metamorphose normally; however, no neoplasms were discovered in larvae sampled from the nonsewage lagoosn. N-nitrosamine analyses of water and tissue samples of larvae were negative. Polycyclic aromatic hydrocarbon analyses revealed traces of benzo[a]pyrene in the sludge; however, perylene, a constituent of jet fuel, was found in high concentration (300 ppb). These results indicate tat preylene, which was previously found not be tumorigenic to mice and rats, should be retested as a possible agent for nonmammalian species.


Prevalence of neoplasia in 10 New England populations of the soft-shell clam (Mya arenaria). Neoplasia was a prevalent disease of the soft-shell clam and was found in widely geographically distinct sites in New England. Two types of neoplasms were recognized. Most were of hematopoietic origin, except in clams from Maine, which also had gonadal neoplasms. Both types were apparently malignant neoplasms, based on their characteristic anaplastic appearance, invasiveness, metastasis, mitotic activity, associated tissue necrosis, and mortality. Diagnosis of neoplasia in the living mollusk was achieved rapidly and accurately by cytologic examination of circulating blood. The etiology of the neoplasms was not identified. In general, nonneoplastic lesions, such as epithelial hyperplasia and accumulations of a orange-brown bodies, were more common in clams from polluted areas.


The theory of encephalization.

The theory of encephalization. The theory of encephalization is developed from elementary dimensional requirements for the construction of a brain of given size. The basic assumption in the theory is that most of the brain in vertebrates is constructed as a series of mappings repeated at various levels. Encephalization is seen as a composite of an amplification factor for the repeated mappings (identical with the encephalization quotient EQ) and a factor associated with "added" tissue. The latter may be viewed as tissue that corresponds to new functions. The relation of the theory to allometric analysis is a relationship of theory to empirical estimation of "expected" brain size at a given body size. But body size is not fundamental to the theory. It is merely one of several possible sources of a measure of the area of a basic mapping, as it were, which is then subject to the amplification factor. Issues in the use of encephalization to assess behavioral capacities are reviewed briefly, as are the neurobiological correlates of encephalization and brain size.


Symmetrical lateralization of function in the auditory system of the cat: effects of unilateral ablation of cortex. We have presented behavioral evidence suggesting that one function of auditory cortex is to attend to stimuli at the contralateral ear. Further, behavioral and anatomic evidence shows that the neural mechanisms for this function probably depend on a pathway that crosses at the level of the medulla, bypasses the superior olive, and ascends to the contralateral inferior colliculus. At higher centers there are several auditory pathways from thalamus to cortex, as well as descending pathways from cortex, and some of these pathways may play a role in selective listening with one ear.


Lateral specialization and psychiatric issues: speculations on development and the evolution of consciousness. At the start of this lecture, I invited you to indulge with me in a "dessert" of speculations. I hope it has been a sufficiency, not a surfeit. In summary, we have examined a hypothetical model of some dissociations of consciousness and the expression of unconscious symptoms in adults; we then explored some possible conditions that would account for the development of separate mental streams. In the course of this exploration we were led to question some basic assumptions about the unity of the self, and we proposed some possible mechanisms by which lateral specialization develops in children. This model of the development of lateral specialization has some implications for the study of evolution of the human brain and consciousness. It would seem useful to examine the relationship between the evolution of the commissural systems and the evolution of different capacities for consciousness. According to this model, the full development of lateral specialization depends upon the later myelination of the commissures, which makes possible the autonomy and competition between hemispheres. By this means, only minimal differences between hemispheres need to be specified genetically, since the rest of lateralization can be produced by progressive differentiation, through interactions with the environment. Thus man's eternal, internal struggle may be the price paid for the evolution of lateral specialization.


An anthropological perspective on the evolution and lateralization of the brain. The purpose of this paper is to review the anthropological evidence relating to the cultural determinants of the right-hand first postaulted by Hertz in his classic study. Also a genetic/cultural conformity model of handedness is presented that postulates that the incidence of handedness in a society is held to result both from the genetic expression of handedness interacting with cultural pressures towards conformity. The evolutionary basis for the hemispheric functional organization into cognitive and perceptual hemispheric functions is discussed in terms of "right-handed dominant homozygotes, DD," "heterozygotes, DR," mixed-handers, and "left-handed recessive homozygotes, RR." The cross-cultural distribution of handedness provides support for this model since the more conforming agriculturalists as measured by the Asch Test have a significantly lower incidence of left-handedness (0.59%, 1.5% and 3.4%), while the more permissively socialized Eskimo and Arunta hunters, who are seen to be more independent on the Asch Test, have 11.3% and 10.5% left-handers, respectively. Also, due to the greater pressures for females to conform in agricultural societies, the incidence of female left-handedness in agricultural societies is 0% out of 330 female Ss, with 3.8%, 0.79%, and 2.5% in agricultural males, as contrasted with the Eskimo hunters who have 12.5% left-handed males and 10.3% left-handed females, showing no significant sex difference. A further Hong Kong-English study also supports the genetic/cultural conformity model with a significantly lower incidence of Hong Kong Chinese left-handers (RR: male = 2.7%, and female = 4.2%). The next section, concerned with the neonatal sex-hormone differentiation and lateralization processes, provides a neuropsychologic theory relating to spatial and linguistic skills that is relevant to the following section, which deals with relationships between laterality and cognitive style. The results are also presented for the Alaskan Eskimo in relation to hand, eye, auditory dominance and cognitive style. The analysis of Eskimo fixed-versus mixed-laterality data also confirms, as predicted, that both within and across a modality (e.g., right hand/right eye/right ear) fixed right-dominance Eskimo Ss are more field-independent than mixed-dominance Ss, while the fixed left-dominance Ss are the most field-dependent and have lower spatial skills. The discussion section reviews the papers relating to the genetic/conformity model of handedness, as well as laterality and cognitive style. The evolutionary adaptive significance of sex differences in gonadal differentiation and lateralization of the brain on spatial and linguistic skills are also reviewed. The conclusions are concerned with the implications for biosocial theory and the rapidly changing incidence of left-handedness due to accompanying changes in cultural pressures both within and across cultures.


The origin of the vertebrate brain.

The origin of the vertebrate brain. The need for a "model" of the development of the head and the nervous system is examined. The purpose of such a model is to facilitate the testing of the probability of the correctness of anatomic and developmental ideas from a number of areas. Without such a model this information presents only a jumble of discordant facts. The proposed model suggests the following: 1. The nervous system of amphioxus tells us little, or nothing, about the ancestral vertebrate system. 2. The gap between the neural tube stage, established in the chordate, and the complex central nervous system typical of the vertebrate is partly closed by the identification of two stages. 3. The first of these stages assumes that the original anterior end of the nervous system corresponded with the anterior end of the notochord: thus it was at the anterior end of the present mesencephalon. Outgrowth of the anterior mesencephalic wall, totally sensory in nature, moved the neuropore anteriorly. This outgrowth is correlated with the gradual conversion of a velar mouth to a biting mouth by forward and downward extension of the head. 4. As a result of the anterior and downward expansion of the anterior wall of the mesencephalon, the cephalic flexure and infundibulum were produced. The primitive eye changed its relationship to the brain from attaching anterolateral to laterally; its point of attachment shifted from dorsal to the neuropore to ventral to the neuropore. 5. The nasohypophyseal field in the neural tube ancestor was closely associated with the anterior wall of the brain below the neuropore, and nerve fibers growing from this epithelium extended to the brain below (posterior?) to the optic stalk. With outgrowth, the fibers now entered the brain substance anterior to the optic stalk and dorsal (?) to the neuropore. 6. The second stage, which is well known from the literature, is the outgrowth of the telencephalic lobes from the dorsolateral and anterior wall of the "diencephalon." 7. Among the vertebrates further elaboration of the system can be documented.


Developmental plasticity of central serotonin neurons after 5,7-dihydroxytryptamine treatment. Systemic administration of 5,7-HT to newborn rats produces an altered development of the 5-HT neurons in the central nervous system, with marked regional differences. 5,7-Hydroxytryptamine can enter the brain and elicit its neurotoxic actions after systemic administration in the neonatal stage due to an incompletely developed blood-brain barrier, which for 5,7-HT is elaborated between postnatal Days 5 and 7. Treatment with 5,7-HT at birth produces marked and permanent 5-HT denervation in the cerebral cortex and spinal cord, whereas hyperinnervation occurs in the 5-HT cell body-near regions (mesencephalon-pons-medulla). The latter effect is seen within the first week postnatally. Treatment with 5,7-HT also affects NA neurons in a similar manner, although the action is exerted preferentially on 5-HT neurons. A selective effect on 5-HT neurons can be achieved by DMI pretreatment, after which both NA and DA neurons develop normally. No signs of any interaction among growing 5-HT, NA, and DA neurons can be observed. Studies of the postsynaptic 5-HT receptor in vitro with [3H]-5-HT and [3H]LSD binding indicate that this receptor develops independently of presynaptic 5-HT nerve terminals. Neither 5-HT denervation nor 5-HT hyperinnervation was accompanied by any change in receptor-binding characteristics or receptor density. The results available are compatible with the view that the consequences for 5-HT neurons that occur after neonatal 5,7-HT administration are mainly due to a "pruning effect." The developing 5-HT neurons seem to be programmed to produce a certain quantity of nerve terminal arborizations, which they try to conserve after 5-HT-induced injury, leading to the observed rearrangement of 5-HT nerve terminals.


Effects of central 5,7-dihydroxytryptamine on the medical hypothalamic syndrome in rats. The present study attempted to replicate and extend two recent studies that implicated aberrant brain 5-HT neurotransmission in the etiology of overeating and BW grain. Adult female rats received 25 mg/kg of desipramine hydrochloride 30--45 min prior to an intracisternal injection of 200 microgram (free base) of 5,7-DHT creatinine sulfate or its 1% ascorbic acid aqueous vehicle. After 7 weeks of measuring food intake, water intake, and BW change, rats from both groups received radiofrequency lesions of the MH or sham surgery. After 5 additional weeks of intake and BW measurements, all rats were tested for 24-hr acceptance of varying sucrose and quinine solutions and for 25-day acceptance of a high-fat replacement diet. While 5,7-DHT depleted brain 5-HT by 45%, it did not induce overeating and BW gain alone nor did it modify the overeating, obesity, or "finickiness" produced by hypothalamic injury. Several factors that relate to specificity, sufficiency, and compatibility with other 5-HT depletory techniques were discussed, as were factors of similarity and dissimilarity between this and the previous experiments that we attempted to replicate.


Tics and Tourette's: a continuum of symptoms? Analysis of the families of 39 unselected children with Tourette syndrome revealed other members with tic disorders in twenty kindreds. In eight families there were 13 individuals with chronic multiple tics, usually motor, not vocal. Twelve different families contained 18 subjects with Tourette syndrome other than the index patient. In three of these families there were 6 additional individuals with chronic motor tics, forming a bridge to the first group. An autosomal dominant mode of inheritance was suggested in all cases. Tourette syndrome and chronic motor tics appear to represent conditions along a continuum and have, in many instances, a hereditary basis.


Bone marrow necrosis. acute microcirculation failure in myelomonocytic leukemia. We saw bone marrow necrosis in a case of acute myelomonocytic leukemia. The diagnosis was made during the patinet's life, and the bone marrow microcirculation was studied immediately postmortem. Histology and injection of the bone marrow arteries showed an acute microcirculation failure. The pathogenesis and possible relationship with soluble immune complexes was studied.


[Generalized glycogenosis (Pompe's disease) in an 11-year-old girl]. A case of cardiomegalic glycogenosis in a girl of 11 is described. The autopsy revealed cardial hypertrophy, hepatomegaly and enlargement of the kidneys. Histologically, diffuse accumulation of glycogen in the heart muscle, liver, epithelium of the convoluted tubules of the kidneys and in skeletal muscles was demonstrated. The features of the observation include the long-term course of the disease and combination of cardiomegalic glycogenosis with hepato-renal manifestations of enzymopathies.


Anesthetic and operative management of potential upper airway obstruction. Potential or actual supraglottic airway obstruction becomes critical when general anesthesia is begun. Four cases illustrated such obstruction, and the anesthetic and surgical management of each condition was critical. In carcinoma of the supraglottic larynx and in pharyngeal abscess, the unobstructed airway in the conscious patient became impossible to secure once general anesthesia was begun. Unappreciated pathological deformity prohibited endotracheal intubation, and anesthesia precipitated obstruction. In epiglottitis and peritonsillar abscess, the nature of the impending airway obstruction was appreciated, and the selection of a safe technique to secure the airway was made. Anesthetic and surgical management of potential supraglottic obstruction includes five options: (1) oral tracheal intubation by laryngoscopy while the patient is awake; (2) awake nasotracheal intubation; (3) inhalation induction by general anesthesia with intubation; (4) rapid induction with barbiturates and muscle relaxants with intubation; and (5) tracheostomy with local anesthesia.


Systemic problems affecting dental treatment. Dental treatment rendered to patients suffering from various systemic problems may need to be varied from that normally given to healthy patients. This paper deals with these problems and recommends the precautionary measures that should be taken to avoid serious consequences.


Antimicrobial action of thymol-camphor compared with 20 pharmaceutical preparations. 1. Staphylococcus aureus. The antimicrobial action of 21 pharmaceutical preparations has been compared in vitro by testing them against Staph. aureus (Oxford strain) in an identical environment. While a number of chemicals produced a degree of action, which can be considered adequate for clinical purposes, the combination thymol-camphor gave the best results.


Alveolar osteitis (dry socket)--a review. The literature on "dry socket" is reviewed. The diagnosis, incidence and predisposing factors are discussed in relation to its aetiology. Treatment regimes are outlined; in particular, the use of anti-fibrinolytic drugs.


The pre prosthetic management of the edentulous patient. The problems to be solved are those largely caused by prolonged wearing of old, inadequate dentures where faulty occlusion, ill-fitting bases, poor denture hygiene, parafunctional habits combine to produce denture stomatitis and papillary hyperplasia. A programme is set out to deal with these problems and to adjust abnormal frenum and muscle attachment.


The effect of alloy composition on the development of internal porosity in cast structures. A number of metallic elements were added singly and in combination to a simple nickel-chromium alloy. The effect of alloy composition was determined by radiographic and metallographic examination.


Regressive formula to determine vertical dimension in the edentulous. The distances between the cephalometric points of 380 patients with complete natural dental arches were measured. A correlation between the bizygomatic, nasion-subnasal and subnasal-gnathion distances and the vertical dimension was established and a mathematical formula was derived to enable determination of both the physiologic rest position and vertical dimension at centric occlusion in edentulous patients.


Crown construction to the lingual margin of a partial denture. A technique is described which ensures that the interface between a newly constructed crown and an existing partial denture is accurate and neither crown nor denture need adjustment. At no time does the patient have to be without the denture. A silver plated die with a double dowelling technique is used.


The use of mixtures of octapressin and adrenaline in local anaesthetic solutions to obtain more effective vasoconstriction. The synergistic effects of felypressin with adrenaline have been studied using the isolated central artery of the rabbit ear as a vascular model. Sub-constrictor doses of felypressin were shown to increase adrenaline's vasoconstrictor effect on this vessel. It is therefore suggested that a mixture of felypressin and adrenaline be used in local anaesthetic solutions in order to provide more effective vasoconstriction.


New units in haematology.

New units in haematology. Results of haematological tests are now reported in Systeme Internationale (SI) units. The new and old units showing normal ranges for the most frequently used tests are presented. Some implications of normal values are mentioned.


What is happening to cavity toilet and lining? There has been a swing toward using chemicals other than air and water for some areas of cavity preparation and cavity toilet. There also have been some new thoughts in the area of linings and bases. This is a discussion in clinical terms of the current concepts in the area between cutting of the cavity and insertion of the restoration.


Orthodontic seminar: a realistic approach diagnosing the problem. Diagnostic guide lines are presented to help the general practitioner to correctly differentiate the "simple" from the "difficult" case of malocclusion. These aids to diagnosis are set out in an orderly fashion to encourage a closer and more systematic examination of the bite of every patient presenting for dental treatment. Certain types of appliances are suggested as adequate to cope with the malocclusion, once the correct diagnosis has been made.


Orthodontic seminar: a realistic approach minimizing the future problem. The role of the family dentist in the utilization of preventive orthodontics to intercept potential problems in the areas of serial extractions, buccal cross-bites and thumb sucking habits is discussed.


Characteristics of the Papua New Guinean dentition. II. Normal occlusion in an adolescent population. Data on dental arch form and size, tooth arrangement and occlusion are presented for 32 adolescents from Wewak, Papua New Guinea, and compared with measurements of similar adult populations. Each person examined had a Class I occlusal relationship.


The present status of proximal gastric vagotomy. It is now clearly established that proximal gastric vagotomy, which has been in clinical use for over seven years, had lower mortality and morbidity rates than all other forms of operation currently used in the treatment of chronic duodenal ulcer. Although no long-term figures are yet available, the ulcer recurrence rates is not likely to be greater than that for truncal vagotomy. The technique is not without problems, however, and has yet to gain wide acceptance in this country.


five years' experience with proximal gastric (highly selective) vagotomy. In the five-year period 1972 to 1976 the author's preferred treatment for patients with chronic duodenal or prepyloric peptic ulcer requiring surgery was proximal gastric vagotomy. In spite of this preference, only two-thirds of such patients were so treated. Most patients with bleeding and stenosis were treated by bilateral truncal vagotomy and drainage, and a few by Pólya gastrectomy. Proximal gastric vagotomy proved to be a safe elective operation without mortality and with a proven ulcer recurrence rate so far of 6%. Compared with those who had bilateral truncal vagotomy and drainage, the proximal gastric vagotomy patients complained less often of diarrhoea but more often of weight loss and reflux. Two patients have had persistent postprandial non-peptic pain, thought possibly due to upper gastric ischaemia.


Surgery for recurrent peptic ulceration. Sixty-six patients having surgery for recurrent peptic ulcers over a 10-year period are reviewed. The majority of the patients were male and developed their initial ulcers at an early age. Bleeding was the most common presenting symptom. Seventy-one percent of the recurrences occurred within three years. Barium meal X-ray examination plus endoscopy gave the correct diagnosis in 96% of cases. The causes of the recurrent peptic ulcers were: (1) incomplete vagotomy; (2) inadequate gastric resection; (3) inappropriate surgery; (4) Zollinger-Ellison syndrome; (5) gastric outflow obstruction; and (6) bile reflux. Other factors such as alcohol, analgesic abuse and psychiatric disorders were found to be common associations. Resection plus vagotomy was the summation of primary and secondary surgery in 85%. The operative mortality was 3%. Eighty-five percent of patients had a Visick grading of I or II. Only one patient had a further recurrent ulcer and this healed on medical treatment.


Mortality trends in the surgical management of chronic peptic ulceration: 25 years' experience. This study is of the results of surgical management of bleeding chronic peptic ulceration at Prince Henry's Hospital, retrospective for the periods 1951 to 1960 and 1961 to 1970 and prospective for 1972 to 1977. During the latter five years all patients were admitted from the community to a haematemesis and melaena unit with a defined policy of management and prospective data recording for computer analysis. There was a continuing improvement in mortality over this 25-year period, especially with duodenal ulcer. No clear distinction could be made between conservative surgery and partial gastrectomy in terms of reduced surgical mortality in duodenal ulcer. Bleeding gastric ulcer remains a difficult problem, with a current surgical mortality of 21%.


The interrelationship between bleeding, perforation, and stenosis in duodenal ulceration. The interrelationship of gastrointestinal bleeding, acute perforation, and pyloroduodenal stenosis was examined in a hospital series of 1,457 patients with duodenal ulcers. The proportion of each complication among the total number of ulcer patients after various periods of ulcer symptoms was determined. There was little variation in the proportion with bleeding as the duration of symptoms increased, whereas the proportion with perforation decreased and the proportion with stenosis increased with increasing duration of ulcer dyspepsia. The association of bleeding with perforation (26 patients) was more common than the association of bleeding with stenosis (12 patients), and more so than the association of perforation with stenosis (4 patients). To explain the paradoxical relationship of perforation and stenosis it was proposed that perforation occurred when the pathological process in ulceration was such that there was more tissue destruction. than tissue repair, and that stenosis would result if there was more tissue repair than tissue destruction


The diagnosis of reflux oesophagitis: an evaluation of five investigative procedures. Five methods of diagnosis have been compared prospectively in 43 patients referred for suspected reflux oesophagitis. A final diagnosis of reflux oesophagitis, as defined by the presence of at least two of the three features of typical symptoms, abnormal endoscopic findings, and abnormal findings on oesophageal biopsy, was made in 27 patients. Observer error in the interpretation of endoscopic and histological appearances was small. Measurement of resting pressure of the lower oesophageal sphincter (LES) failed to identify individual patients with reflux oesophagitis, although the mean pressure in 26 patients with oesophagitis (10.1 +/- 5.2 mm Hg) was significantly lower that in 13 patients without oesophagitis (16.8 +/- 10.2 mm Hg, P less than 0.005). Barium studies were unhelpful, as a hiatus hernia was present in only 14 and barium reflux in only 11 of the 27 patients with oesophagitis. Acid perfusion (Bernstein test) was positive at 15 minutes in 23 of the 27 oesophagitis patients, but was falsely positive in seven of the 14 patients without oesophagitis. By accepting only those responses to acid perfusion which were positive at or before seven minutes, the false positive responses were reduced to one out of the 14 patients. Typical symptoms and/or an early positive Bernstein response will correctly identify most patients with reflux oesophagitis, but the diagnosis should be confirmed by endoscopy and biopsy when important therapeutic decisions are pending.


Achalasia cardia: a review of 100 cases. Achaiasia cardia is the commonest benign obstructive lesion of the oesophagus in India. We have reviewed 100 cases over a 20-year period. This is the largest series that has been reported from India. Some unusual features were observed. Males were more often affected than females in a ratio of 2.3:1. Children below the age of 10 years are not often affected, but we had 10 subjects in this age group. In our series dysphagia for solids has been the main presenting feature. Barium swallow X-ray studies of the oesophagus were diagnostic. The treatment of choice had been surgical, and a modified Heller's operation has been the chosen procedure. Our preference is for the thoracic approach. Postoperative complications were few. Long-term follow-up of 65 patients over a 19-year period revealed excellent results in 50 patients (76.9%), good results in 10 (15.4%), and fair and poor results in two (3.1%) and three (4.6%) patients respectively. The fair and poor results occurred in patients with recurrence of symptoms or stricture formation due to reflux oesophagitis. The excellent results even on long-term follow-up, we believe are due to the adequate myotomy that was performed.


Colorectal carcinoma in Hong Kong.

Colorectal carcinoma in Hong Kong. The clinical and pathological features of colorectal carcinoma occurring in 470 Chinese patients in Hong Kong are reported. There was a preponderance of advanced stages of the disease in spite of the presence of a large number of well-differentiated lesions. Polyposis coli was the predisposing cause in 1% of our patients, and none of them had ulcerative colitis. The clinical features of our patients on presentation were generally similar to those exhibited by Caucasians. An abdominal mass was palpable in about half of patients with colonic lesions, and virtually all rectal cancers could be felt by rectal examination. Almost a quarter of our patients presented with complications. In 2% of our patients the initial diagnosis was acute appendictis. A high resection rate was achieved, but many radical resections turned out to be only palliative. Our operative mortality was 8.3%, although for social reasons, the "in-hospital" mortality was 19.2%. The corrected five-year survival rate was 42.7% when curative resection was attempted.


The significance of widening of the presacral space at contrast radiography in inflammatory bowel disease. The width of the presacral space was measured prospectively at various levels in 100 persons without organic colonic or rectal disease who had barium enema X-ray examinations. A standard technique was employed. The most consistent measurement was obtained at the level opposite the S3-S4 disc space; readings varied between 2 mm and 16 mm. Using 16 mm as the upper limit of normal, and a similar technique of barium enema examination, the width of the presacral space at the S3-S4 disc level was measured in 66 patients with inflammatory bowel disease (ulcerative colitis--49; Crohn's colitis--17). The width did not correlate with the severity of the disease process as indicated by sigmoidoscopic examination in proximity in time to the radiological examination. There was a relationship between increased width of the presacral space and the duration of the disease process.


Bile peritonitis after the use of latex rubber T-tubes. Three cases of biliary peritonitis following the removal of a latex rubber T-tube from the common duct in the second postoperative week are reported. This is a well-recognized complication following the use of polyvinyl chloride T-tubes in biliary duct surgery, but its occurrence with latex rubber T-tubes is extremely uncommon.


Villoglandular adenoma of the duodenum.

Villoglandular adenoma of the duodenum. Two cases of villoglandular adenoma of the duodenum presenting with features of peptic ulcer are reported. At surgery both patients had intussusception of the duodenum. One of them had carcinoma in situ. The literature is briefly reviewed, and the importance of keeping in mind this rather rare condition, even in areas where duodenal ulcer is widely prevalent, is emphasized.


Duodenal haematoma in association with coeliac axis stenosis. Duodenal haematoma is now a well-established clinical entity. The aetiology, however, is not always clear. Trauma or bleeding due to anticoagulant therapy is the cause in most cases. It is suspected that unreported minor trauma may cause the remainder. A case is reported in which the pancreaticoduodenal circulation was markedly dilated and tortuous because of severe coeliac axis stenosis. It is suggested that no trauma is required in this situation to cause bleeding, which may be due to spontaneous repture of the smaller vasa recta.


Fatal cholangitis after endoscopic retrograde cholangiopancreatography in congenital hepatic fibrosis. A patient with congenital hepatic fibrosis is described in whom portal hypertension with variceal bleeding was the predominant symptom, accompanied by a minor episode of cholangitis Endoscopic retrograde cholangiopancreatography disclosed intrahepatic bile duct strictures, tortuosity, and tubular dilatation, but not cystic dilatation as typical of Caroli's disease, in which cholangitis is known to be the predominant feature. Following the procedure, the patient developed fulminating cholangitis and septicaemia, and died despite surgical decompression of the biliary system.


Operative biopsy of the pancreas using the Trucut needle. The results of 14 operative biopsies of the pancreas using the Trucut technique are presented. There was no significant complication attributable to the biopsy, and in all cases an adequate tissue specimen was obtained, facilitating either frozen or paraffin section histological diagnosis. One false negative result was obtained which was due to sampling error. This technique is recommended as a good alternative when operative pancreatic biopsy is required. It is technically simple, has an acceptably low sampling error, provides a good tissue specimen for histological examination, and has few complications.


Anterior and posterior ruptures of the urethra: simplified methods of immediate surgical management. The aetiology and relative incidence of anterior and posterior ruptures of the urethra are briefly discussed. Methods of surgical management of both types of injury are described, which obviate any necessity to expose the site of rupture. A series of five such cases is reported, the outcome in each being satisfactory.


Arterial ligation in epistaxis.

Arterial ligation in epistaxis. Unremitting severe nose bleeds may require arterial ligation. One or more of the four vascular systems supplying the nose may need such surgical interference. Dye injection of 14 cadavers was performed to demonstrate the vascular supply of the nose and the effects of various arterial ligations. Depending upon the site of haemorrhage within the nose, up to three vascular systems may need occlusion. These are the ipsilateral and contralateral external carotid arterial systems and the ipsilateral ethmoidal arteries.


Peptic ulcer and gastrin in pigs.

Peptic ulcer and gastrin in pigs. Previous studies have shown that bile duct ligation in pigs results in gastric ulceration. It has been suggested in human peptic ulceration that there may be no associated rise in the serum gastrin level. This study was conducted to determine the portal and peripheral gastrin levels in sham-operated and bile-duct-ligated pigs, together with the basal acid concentration and the response to a protein meal. There was an increase in basal acid concentration in bile-duct-ligated animals, but the serum gastrin levels remained in the normal range. Two of the six sham-operated control pigs had peptic ulcers at the time of sacrifice, and these two were the only sham-operated control pigs which did not demonstrate a significant postoperative rise in the serum gastrin level. At no stage was a significant difference between portal and peripheral vein serum gastrin levels demonstrated. These studies suggest that the increased gastric acid secretion in this form of peptic ulceration in the pig may not be entirely gastrin-mediated.


Interferon production in leukaemia.

Interferon production in leukaemia. Leucocyte interferon production in vitro and circulating interferon levels were studied in healthy subjects and in 80 patients with acute or chronic leukaemia. Circulating interferon was not found in either group. Interferon synthesis in response to a virus was normal in patients with acute leukaemia and appeared to be enhanced in some. In chronic leukaemia reduced levels were common particularly in CLL, in which condition normal results were rarely found; lymphocyte transformation to PHA was also depressed in this group. No clinical or haematological correlation with the interferon levels was found and no consistent effect of treatment was shown. The possible factors which could account for these findings and their significance in relation to pathogenesis and treatment of leukaemia are discussed.


Remission induction in chronic granulocytic leukaemia using intermittent high-dose busulphan. In a series of 19 patients, the pre-blastic phase of chronic granulocytic leukaemia was controlled with busulphan given as single doses of 50-100 mg at 2-weekly intervals. Although there was no significant increase in the incidence of Ph1-negative cells in the bone marrow, remissions of a better haematological quality were attained more rapidly than with conventional therapy.


Metabolic disorders in acute myeloid leukaemia. Metabolic balance studies were carried out in 17 unselected patients with acute myeloid leukaemia. Widespread metabolic disturbances were observed. Serum Na fell below 135 mmol/1 in 14 patients (82%) and 11 patients (64%) developed hypokalaemia. An increased osmolal clearance caused by a release of electrolyte and blast cell waste (i.e. urea, urate, etc.) during chemotherapy appeared to be the principle cause of natriuresis and hyperkaluria. Seven patients had proteinuria before and eight others developed it during antileukemic therapy. Nine patients (53%) developed proximal renal tubular dysfunction with aminoaciduria, hyperphosphaturia and incomplete reabsorption of urate. No significant relation was found between this widespread glomerulo-tubular dysfunction and lysozymuria. We suggest that antileukaemic drugs release unidentified substances from blast cells which are toxic to the kidney. Metabolic alkalosis in six patients (35%) was probably related to volume depletion and hypokalaemia, while two patients developed acidaemia with the onset of renal failure. Hypocalcemia in seven patients (41%) had a multifactorial basis: hyperphosphaturia, septicaemia, malnutrition and cytotoxic drugs were among the probable causes.


Loose bodies of the temporo-mandibular joint, synovial chondromatosis or osteoarthritis. A patient is presented with multiple intra-articular loose bodies of the temporo-mandibular joint, the aetiology and management is discussed. In the absence of histological proof of metaplasia within the synovium the mechanism of cartilage production is open to question. Attention is drawn to the diagnostic problem in long-standing cases when osteo-arthritis supervenes. The clinical picture presented may represent the late stages of synovial chondromatosis or degenerative joint disease from another cause.


Osteochondritis dissecans affecting the temporo-mandibular joint. A case of a single loose body occurring in the temporo-mandibular joint is described. It is probable that this case represents the degenerative process of osteochondritis dissecans, a condition not previously described in this joint. The essential features of this condition are noted as a comparison to the condition of synovial chondromatosis.


Collapse of the condylar head of the mandible in children and subsequent ankylosis. Five cases are reported of children who presented with limitation of jaw movement and had some degree of deformity with shortening of the mandible on the affected side. X-ray examination demonstrated changes in the head and neck of the mandibular condyle. There were varying degress of sclerosis and new bone formation in the area extending from the neck of the condyle into the sigmoid notch. The left side was affected in each case. Parallels are drawn with Perthes' disease, and although the temporo-mandibular joint is not weight-bearing, in both conditions avascular necrosis is likely to be involved. Both have similar X-ray appearances. The fragmentation of the epiphysis in the later stages causes widening and collapse of the head of the femur and the mandibular condyle.


Cherubism--an initial unilateral presentation. An unusual presentation of cherubism is reported owing to the initial unilateral nature and late onset of occurrence. A classification for cherubism is proposed and the difficulty in diagnosis of unilateral cases is discussed.


Cherubism: a report on three cases.

Cherubism: a report on three cases. Three cases of cherubism not previously recorded in the literature are described. They are three members of a Greek Cypriot family; the mother aged 49 years had residual mandibular deformity; the first daughter aged 17 years had facial swelling and anterior rib lesions; the second daughter aged 14 years presented with a unilateral giant-cell granuloma in the mandible.


Maxillo-facial injury in severe haemophilia. A case of maxillo-facial injuries in a patient with severe haemophilia is described. Problems of treatment and management are discussed from both surgical and haematological points of view.


Ameloblastic fibroma: report of two cases. Two cases of ameloblastic fibroma are described. One case was a seven-year-old girl, the other a 13-year-old boy. In both cases the tumour was located in the posterior part of the maxilla. Both neoplasms were associated with failure of tooth eruption, in one case a primary molar, in the other case a permanent molar. Local excision was performed in both cases, with a recurrence observed in one case ten months after surgery.


Staphylococcal sub-mandibular lymphadenitis in childhood. Thirteen cases of staphylococcal sub-mandibular lymphadenitis in children are presented and the diagnosis and treatment are discussed. All but one of the strains of Staphylococcus aureus isolated were resistant to penicillin, while the converse was true for erythromycin. Epidemic strains of Staphylococcus aureus were not found when bacteriophage typing was carried out on isolates from seven of the 13 patients.


An adverse reaction to a topical antiseptic (cetrimide). A case of contact dermatitis due to the pre-operative preparation of the skin with 'Savlon'1 is described. Testing suggested that this was due to cetrimide. The nature of this reaction, its investigation and treatment, are discussed.


Properties of purified folate-binding proteins from chronic myelogenous leukemia cells. Folate-binding protein(s) from chronic myelogenous leukemia cells have been purified using acid dialysis, ammonium sulfate fractionation and affinity chromatography. The purified preparation which migrates as a single band on disc electrophoresis could be separated by DEAE agarose chromatography into two folate-binding proteins (binders I and II) which bind molar equivalents of folic acid. One binder (I) eluted from DEAE at 1 mM sodium phosphate, pH 6.0, and the other (II) at 100 mM sodium phosphate, pH 7.4. Analysis of the purified mixture, which contained more than 90% binder II, by sedimentation equilibrium centrifugation indicated a homogeneous protein with a calculated molecular weight of 44000. Antiserum raised against the purified mixture gave a single precipitin line by immunodiffusion against a preparation of partially purified cell lysate. Hydrolysis of the more acidic binder (II) with neuraminidase converted it to a weakly acidic protein similar to binder I, suggesting that these binders are glycoproteins which differ in sialic acid content. With isoelectric focusing, the binding of folic acid could be demonstrated at pH 6.7, 7.3, 7.8 and 8.2 for binder I, and at pH 5.1, 5.8, and 6.5 for binder II. Binders I and II had equally high affinity for folic acid and dihydrofolate, lower affinity for N5-methyl-tetrahydrofolate, and no apparent affinity for N5-formyltetrahydrofolate or methotrexate.


Chronic oesophageal stricture due to moniliasis. A case of persistent oesophageal stricture due to moniliasis, which developed while the patient was symptomatic, is reported. The value and therapeutic implications of performing a repeat barium swallow even if the disease appears to be quiescent are discussed.


Factors associated with prolonged survival in chronic myeloid leukemia. Four patients who demonstrated unusually prolonged survival with Philadelphia chromosome positive Ph' (+) chronic myeloid leukemia (CML) were analyzed for factors associated with survival. Survival duration from initial diagnosis ranged from 120 to 222 months, with a mean of 170 months. At diagnosis, age, symptoms, liver or spleen size, hematocrit, white blood cell count, absolute peripheral myeloblast plus promyelocyte count, and uric acid did not have unique prognostic significance. At diagnosis all four patients had normal or low-normal platelet counts, (range: 170,000 to 248,000/mm3). Thrombocytopenia occurred during treatment in three patients. None of the four patients, however, developed severe marrow hypoplasia or leukopenia during treatment for the chronic phase. Cytogenic studies performed from 103 to 156 months after diagnosis did not reveal a large subpopulation of marrow cells with a normal karyotype or cells with the XO genotype in the male patients. These observations suggest that prolonged survival in CML 1) is not contingent upon intensive treatment resulting in marrow hypoplasia, and 2) does not require the persistence of a clone of karyotypically-normal bone marrow cells or a clone of marrow cells in males which has lost the Y chromosome. A normal or low-normal platelet count at diagnosis may be a favorable prognostic indicator.


Acute leukemia in Malaysian children.

Acute leukemia in Malaysian children. A review of acute childhood leukemia in the University Hospital, Kuala Lumpur reveals no significant differences in either the epidemiological or clinical features between Malaysian and Caucasian children. BCG does not appear to have conferred any protection against the occurrence of leukemia. With the introduction of total therapy 4 of 10 patients with good prognostic features and 3 of 15 patients with poor prognostic features have survived 3 years. Prognosis appears to correlate with adopted clinical criteria.


Acute myelomonocytic leukemia following a chemotherapeutic regimen for metastatic sarcoma. Acute myelomonocytic leukemia developed in a patient 18 months after treatment with cyclophosphamide, vincristine, adriamycin, and DTIC, a chemotherapeutic regimen used for the treatment of metastatic sarcoma. The patient had had no prior history of radiation. More than 400 patients received this treatment and none of them developed leukemia. The occurrence of leukemia in this relatively short period of time may have been caused by the combined chemotherapeutic agents. However, confirmation of this will require long-term followup studies in cancer patients receiving chemotherapy to determine the true risk of second malignancies.


[Use of various technics in the classification of hematopoietic system tumors]. A comparison of three groups classified according to three different methods (89, 91, und 278 cases respectively) confirmed that the main oncological features of haematopoietic tissue tumours should be sought in their cytological-histological properties.--The spectrum of methods employed (histochemistry, immunohistology, electron microscopy) may in individual cases underpin the decision-making process especially when the appearance of tumour cells has been altered by advanced anaplasia. Partial results of these methods judged in isolation may, however, be conductive to wrong interpretation. That is why special significance should be attached to thin sections of tissue stained according to Giemsa as they combine the advantage of histology with those of cytology.--In the basic classification the pathologist can do with the conventional haematological classes of tumours (granulocytic, histiomonocytic, lymphocytic, erythrocytic, megakaryocytic, mixed, and unclassifiable). In the lymphocytic series it was necessary to proceed not only according to immaturity but also according to the blastic transformation of the initial elements.--The principal outstanding problem is that of a positive mutual distinction between blastically transformed lymphocytes and between those and cells of the reticulum.


[Electron microscopy as a method of classification of hematopoietic-system tumors]. 83 biopsies of lymph nodes and 35 specimens of blood in different types of haematopoietic system oncological involvement were examined electronoptically with a view to finding distinguishing features such as would prove to be better than other methods used in diagnosing the above tumours. In the granulocytic series these proved to be granules though there was a loss of their formation in most of the poorly diagnosable processes. However, it proved to be relatively easy to make use of tests for phagocytosis in myelomonocytes. In the histiocytic series the defining features (phagocytosis and proteosynthesis) proved to be too general in nature to find any relevant use in oncological diagnosis. On the other hand, the rod-like granules of Langerhans' cells proved to be a reliable guide in diagnosing histiocytosis X similarly as the Weibel-Palade granules did in diagnosing endotheliosis. In the lymphocytic series, B series diagnosis can be facilitated by the presence of spatially arranged interdigitations; in the T series interdigitations are either missing or else are arranged in a single plane only. The erythrocytic series is defined by the presence of ferritin while megakaryocytes are defined by the phenomenon of fissure-like communications.--All those features were merely supplementary in nature and could not be used as an independent diagnostic method particularly in view of the small volume of the processed specimens as these did not always contain representative material or else supplied it in a hardly classifiable mixture.


Dexamethasone antagonism of glucose dyshomeostasis in endotoxin shock. Dexamethasone acetate (100 microgram IP) protected male Holtzman rats (300-330 gm) against endotoxin shock due to Salmonella enteritidis lipopoly-saccharide B IV. Endotoxin (5.0 mg/rat) produced hypoglycemia within 180 minutes, ie, plasma glucose fell from 87 to 24 mg/dl; dexamethasone prevented the hypoglycemia, ie, plasma glucose levels were 129 mg/dl at 180 minutes after endotoxin. Dexamethasone antagonized both endotoxin-induced depression of hepatic gluconeogenesis and enhanced glucose oxidation as evaluated in vivo. Epididymal fat pads from endotoxic rats (100-110 gm) had increased rates of glucose oxidation as evaluated by the in vitro conversion of 14C-D-glucose to 14CO2. Dexamethasone both in vivo and in vitro antagonized endotoxin glucose hypercatabolism by isolated epididymal fat pads following administrated of endotoxin. Glucocorticoid protection against endotoxin shock is related to antagonism of glucose dyshomeostasis.


Osteosarcoma: a review of 50 patients treated at the University of Alabama in Birmingham Medical Center between 1944 and 1975. Only 12% of 50 patients lived 5 years or longer. Those who survived the longest were those with the tumor in the distal part of the lower extremity, with a well differentiated or chondroblastic tumor, or those who underwent radical surgery. Patients treated with surgery and chemotherapy lived about 1.5 months longer than those treated with sugery alone and about 1.2 months longer than those who had radiation included in the therapy. For a patient with a diagnosis of osteosarcoma, the prognosis was to be grave, no matter which methods of treatment were used.


Childhood leukemia presenting as a diaphyseal radiolucency. A 41-month-old black child with a symtomatic diaphyseal destructive lesion of the femur, and a corresponding area of increased uptake on a technetium99m bone scan, had an upper respiratory tract infection. An open biopsy was performed because of an initial clinical diagnosis of osteomyelitis, histiocytosis X or a round cell sarcoma. The biopsy showed numerous blast cells compatible with acute lymphocytic leukemia. Acute leukemia should be included in the differential diagnosis of symptomatic diaphyseal destructive lesions in children. A peripheral blood smear should be carefully interpreted prior to any other invasive diagnostic tests.


Colloquium--is there a surgical cure for pain? We have heard today that psychological factors are extremely important in pain problems and that careful psychiatric assessment should delineate patients who have the potential of achieving good pain relief with interventional procedures. The bulwarks of the neurosurgical management of pain have been peripheral neurectomy, rhizotomy, sympathectomy, and cordotomy. We have heard each of these discussed. Peripheral neurectomy and rhizotomies are not highly successful in the treatment of pain, but are useful in carefully chosen patients. Cordotomy remains an excellent technique for the management of many patients with chronic pain or malignancy, and sympathectomy can be one of the most gratifying operations performed, as long as the patients are well chosen. The major lesson we have learned today is that there is no cure for pain at the present time. Nevertheless, neurosurgical procedures remain an important part of pain management. They should be applied after an adequate diagnosis is made, after psychiatric characterization of the entire pain problem is complete, and only when there is only a definitive pain generator which can be relieved by an interventional procedure. Perhaps the most important message we have heard is the categorization of pain patients given us by Doctor Hendler. It is important that we all identify those patients with affective or exaggerated pain behavior so that interventional procedures are carried out only on those patients who have a real possibility of benefiting from them. I believe if we all do this, we will see a significant increase in the effectiveness of surgical procedures for pain.


Prophylactic lung irradiation in the treatment of osteogenic sarcoma. A minimum 52 month follow-up is recorded, in a series of 14 patients with classical osteogenic sarcoma treated by limb irradiation followed in the last 2 1/2 weeks of their therapy by prophylactic lung irradiation. Six of these 14 patients survived for more than 52 months.


[The use of a focused arc welding technic for gold and cobalt-chromium-molybdenum alloys]. Joint work on small amounts of dental alloy Au-Ag-Cu (10 x 10 x 1 mm) and Co-Cr-Mo (20 x 10 x 1 mm) is relatively simple with the microplasma welding technique. The welding results are good after a short practice period. The welding technique should be improved in two points. The suitability and reliability of welding should be studied.


[Clinical observations on the mobility of natural teeth in patients with partial dentures]. During the course of the study treatment consisted of individual motivation training and instruction in basic dental hygiene, two thorough cleansings, and careful daily plaque controls. The effect of periodontal treatment on the degree of inflammation, mobility, and periodontal pocket depth was determined at the end of a 20 day period of observation. Plaque controls appear to be more significant for the periodontium than stress exerted on the residual teeth.


[Animal experimental studies on the biocompatibility of resorbable gelatin sponges and dry fibrin foam]. Histologic specimens taken from the implantation site and the regional lymph nodes up to four weeks after subcutaneous implantation of Gelastypt S (Höchst AG), Gelfoam (Upjohn), and Fibrospum (Promonta) into the upper hind leg of guinea pigs were examined. Similar tissue reactions were observed with Gelastypt S and Gelfoam; the reactions did not differ appreciably from those normally occurring in the context of wound healing. The predominance of round cell infiltrate and the appearance of giant cells in connection with Fibrospum may indicate an immunogenetic potency of the substance. No signs of beginning resorption could be observed four weeks later.


[Photogrammetric studies on the degree of swelling in the inflamed gingiva]. A photographic method was described with which changes in the swelling of the gingiva can be objectively determined. During exposure of the film, the flash device projects vertical lines on the teeth and gingiva. These lines are photographed with a compact camera which the subject holds with his teeth over a separate occlusion template. Increased swelling of the gingiva was demonstrated in eight subjects during an observation period of 21 days in which no oral hygiene was carried out.


[The problem of characterization of sterins in the gingiva by means of gas chromatography--mass spectrometry]. Methods suitable for demonstrating previously unidentifiable substances in healthy and diseased gingiva via gas chromatography/mass spectrometry were described. The advantage of these methods is that the substances can be directly demonstrated from the tissue available. The steps necessary to isolate and demonstrate the substances were explained on the basis of the phytosterol campesterol.


[Solubility and degree of hemolysis as methods for the in vitro evaluation of dental filling materials]. For the biological examination of dental resin filling materials, a solubility and hemolysis test is recommended as an in-vitro testing method. Solubility and degree of hemolysis were examined in various filling materials based on MMA and BIS-GMA. It was found that, at the beginning, solubility was considerably higher in MMA-containing materials than in the BIS-GMA systems, and that after a while the conditions were reversed. The degree of hemolysis decreased in the following order with the individual materials: 1. Posite, Sevriton, Adatpic, 2. Epoxylite, Smile, Palakav, 3. MMA-BPO/Amin and MMA-TBBO. Comparison between the MMA and BIS-GMA monomers showed that corresponding to the same molar amounts, BIS-GMA materials developed a higher degree of hemolysis.


[Malformations of odontogenic tissue in prehistoric human bone material. A contribution to the differential diagnosis of odontomas]. Three cases of hard tissue formations of odontogenic origin are presented. The objects were discovered among skeletal finds in prehistoric settlements. The morphology of these objects is described with macroscopical, histological, and radiological methods. All three cases are odontomas. The differential-diagnostic possibilities of these formations, their development and the frequency of their occurrence are discussed. Odontomas are not interpreted as tumors, but rather as malformations and are contrasted to blastomas of odontogenic tissues (e.g. ameloblastoma).


A study of procedures to assess care and continuing dental education. Although some studies have been undertaken to assess the effectiveness of continuing medical education in improving the standard of medical care, no comparable studies have been made in the case of continuing dental education. This paper reports the results of a study in progress in the State of Washington, USA which attempts to assess the relationship between participation in various forms of continuing dental education and the quality of performance of selected aspects of dental care. One hundred and five dentists in general dental practice for more than 25 hours per week were studied by means of a questionnaire and by peer review of selected patients. Those forms of continuing education requiring active participation by the dentist rate more highly than more passive forms such as lectures, journals, etc. both in the acceptability to the dentist and in relation to the standard of dental health of his patients. There remain many variables which cannot yet be fully assessed which determine the dentist's perception of need for continuing education and its effectiveness in raising the standard of dental care which he provides for his patients.


Some thoughts on dental education.

Some thoughts on dental education. It is suggested that immediately after dental school there should be a pre-registration year--a whole year of clinical training and instruction in general practice under the close supervision of a competent general practitioner/teacher. This year should end with a period of 3--4 weeks at the dental school for feedback discussion, seminars and some examinations. In order to involve every dentist, teacher, therapist, hygienist, assistant technician in a well-planned continuing educational program it seems necessary to introduce a compulsory system. It is also suggested that there should be a control system for the quality of care and individual professional performance. The demand for dental care increases. It is therefore highly desirable to utilize modern preventive measures on a broad scale, more effective and careful planning of the dental services for the individual patient and for the community as a whole and increased quality of treatment in order to reach a better prognosis and more ancillary personnel.


Program planning for effective continuing dental education. Continuing dental education can only be effective if it is efficiently planned and presented. It is essential to determine the needs as seen by the dentists and to ensure that these needs can best be met by educational means. The potential participants in the programme must then be identified and times and locations most convenient for them be established. The precise purpose and objectives of the course must be clearly stated and detailed organisation can then be commenced. The principles involved in adult education should be clearly understood and appropriate learning aids should be prepared. Evaluation of the programme is essential in order that adjustments can be made to future programmes to correct deficiencies which have been identified and so that the impact on the participants' practices can be assessed.


Distribution of occlusal traits in a sample of 1337 children aged 15--18 residing in upstate New York. Preliminary findings on the distribution of occlusal traits (COCSTOC-MOT) have been presented as measured on 1337 orthodontic models. These models were made from a sample representing more than 400 000 children ages 15 to 18 in Upstate New York (all of New York State with the exception of New York City). Some of the findings for occlusal traits in this survey are comparable to those from a representative sample of younger children representing the US population ages 6--11 years. For comparable traits differences between the findings in New York State and for the United States were: Openbite--1 per cent higher in the US sample. Overjet 6 mm or more--5.7 per cent higher in the US sample. Neutro-occlusion--7 per cent more in the US sample. Disto-occlusion--8 per cent more in the US sample. Mesio-occlusion--8 per cent more in the US sample. Differences in findings between these surveys are assumed to be largely due to the fact that the current survey measured occlusal traits in the permanent dentition; whereas, the US survey measured those traits in the mixed dentition. Some of the traits found in the mixed dentition are believed to be self-correcting. Statistically determined means and medians for some of the occlusal traits of COCSTOC indicate that there is considerable variation from ideal occlusion found in a large population.


Dextrothyroxine treatment of phosphorylase-kinase deficiency glycogenosis in four boys. Four boys, aged 2 years 5 months to 3 years 7 months, with large hepatomegaly due to phosphorylase-kinase deficiency glycogenosis, were given a trial of sodium dextrothyroxine (D-T4) at a mean dose of 0.165 mg/kg/day for an average period of 6 months. Phosphorylase-kinase was undetectable in the haemolysates of erythrocytes (3 patients) or in the liver (one patient) before, and still undetectable in the haemolysates of the four patients during treatment, thus pointing to X-linked phosphorylase-kinase deficiency glycogen storage disease (GSD IXb). D-T4 administration resulted in complete normalization of liver size, decrease of serum GOT (p less than 0.02), GPT (p less than 0.05) and triglycerides (p less than 0.01) to normal values, as well as correction of mild asymptomatic hypoglycemia (p less than 0.01). As long as the outcome of type IXb glycogenosis in adult life remains undefined, dextrothyroxine therapy seems an effective means of reducing liver size and correcting part of the biochemical abnormalities of the disease.


The effect of primary-canine extraction on the IMPA. One can expect to lose IMPA or arch circumference after extraction of the primary canines, if the child presents with an initial FMIA of 64 degrees or less. If the initial FMA is 28 degrees or greater, one can probably expect to lose IMPA, if the primary canines are extracted. One may tentatively suggest that in patients with normal FMA's and FMIA's, the extraction of the primary canines will not appreciably affect the IMPA. Space maintainers may not be needed in such cases. Of the twenty-two patients who had primary canines extracted, ten patients lost IMPA and twelve patients had no change or an increase of IMPA. The findings of this study should be replicated with a larger patient sample.


Color of dental restorative resins.

Color of dental restorative resins. The color of 7 composite resins, an unfilled restorative resin, and 3 glaze coatings was determined by reflection spectrophotometry and visually with Munsell color tabs. Statistically significant correlations existed between comparable parameters of the spectrophotometric and Munsell data. There was observable color variations among the 11 resins studied, but only 3 materials were within the range for natural tooth color.


Polyurethane elastomers as maxillofacial prosthetic materials. A series of polyurethane elastomers based on an aliphatic diisocyanate and a polyether macroglycol was polymerized with various cross-link densities and OH/NCO ratios. Stoichiometries yielding between 8,600 and 12,900 gm/mole/crosslink and an OH/NCO ratio of 1.1 resulted in polymers with the low modulus, yet high strength and elongation necessary for maxillofacial applications.


Thermal stress in teeth.

Thermal stress in teeth. Observations of crack damage in the tooth structure from in vivo studies and in vitro experimental thermal cycling studies were combined with numerical analysis techniques to identify and isolate the influence of thermal stresses on the creation and propagation of cracks in teeth. The factors considered in this study included: (a) variations in tooth type or geometry (molar, bicuspid, etc.), (b) tooth age, (c) material properties of the tooth, (d) the magnitude of the change in the temperature of the environment surrounding the tooth, and (e) the thermal resistance between the tooth and the medium surrounding the tooth.


Physical properties of zinc phosphate cement prepared on a frozen slab. The physical properties of a zinc phosphate cement prepared on a room temperature slab were compared to those of the cement prepared on a frozen slab. Solubility, compressive strength, and setting time of cements prepared on both types of slabs were within the limits set by A.D.A. Specification No. 8.


Bending deformation studies of orthodontic wires. Bending deformation has been measured for orthodontic wires ranging in diameter from .010 to .051 inch. Results establish a revised expression for Young's modulus and show that either the stiffness tester or the torque meter will yield essentially the same measured values of bending properties. The dependence of test span length in determining Young's modulus and flexural yield strength is discussed.


Characterization of Bacterionema matruchotii calcification nucleator. The nucleator of Bacterionema matruchotii calcification was characterized. Parameters examined were: proteolipid purity and singularity, amino acid composition and relative polarity, phospholipid composition, apoprotein homogeneity, essentiality of the complex for nucleation, and ordered structure. The data fulfill a requirement for comparisons among apatite-nucleating proteolipids.


Effect of isoprenaline on salivary gland lipids of rats fed a choline-deficient diet. Male adult rats were fed choline deficient and a choline-supplemented diet for 3 weeks. Half the rats from each group were injected with isoprenaline (16 mg/kg body weight) and the remainder with saline. After 2 and 8 hours, rats were sacrificed, their submandibular salivary glands were disected out, and extracted for lipids. The fatty acid composition of total lipids and some neutral and phospholipid fractions were determined. Isoprenaline administration resulted in a slightly higher level of oleic acid in SMSG of rats fed choline-deficient but not the control diet. There was an increase in the free fatty acid (FFA) concentrations of the gland after 2 hours of isoprenaline treatment in rats fed the control diet; no such increase was observed in the choline-deficient group. The fatty acid composition of FFA fraction was also slightly changed as a result of isoprenaline treatment, but only in the choline-deficient group. The fatty acid composition of triglyceride (TG), phosphatidyl choline (PC), and phosphatidyl ethanolamine (PE) fractions was not changed.


How will dental education adapt to the third-party payment system? An increasing number of dental patients will contract for and pay a third party to assume the fiscal responsibility for their dental care. Dental schools, through faculty and students, regularly provide the most carefully monitored, high quality dental services. Dental schools must continue to provide these services in the most "deinstitutionalized" and personalized manner possible. Third parties, whether commercial or governmental, must assure their clients (dental patients) of comprehensive dental coverage and reimbursement policies that are realistic, equitable, and based only upon receiving quality coverage. The quality of the dental educational system is essential to the success of any dental health care program.


Sabbatical policies and their implementation at United States dental schools. An ad hoc Committee on Sabbaticals created by the Council of Faculties of the AADS surveyed sabbatical policies and their implementation at dental schools in the United States. Data from a questionnaire completed by 56 of 60 members of the Council of Faculties reveal that a majority of U.S. dental schools have sabbatical policies but that dental educators are less likely to apply for or to be awarded sabbaticals than educators from other parts of the university, except perhaps the medical school. Information was also obtained on the regulations governing sabbaticals--interval between leaves, rates of remuneration, and rules defining how the leave may be spent. Finally, suggestions are made as to how this important benefit of academic life might be made more available to dental educators.


Factors affecting patient completion of treatment within a student dental clinic. Failure of dental patients to complete their treatment challenges the efficient use of human and clinic resources, expectations of improved patients' health, and the dentist's effective management of his patients. Accordingly, the present study was undertaken to explore factors which might account for adult patients not completing their treatment at the University of North Carolina dental school. These factors were simultaneously considered as determinants of completed treatment. Possible explanations were considered from providers' (dental students') as well as inactive patients' points of view. Results revealed substantial agreement between patients and students, and yielded the following general determinants of treatment completion: patient's availability for treatment, how cooperative or treatable the patient was, and the patient's satisfaction with treatment. Demographic explanations were minimal. The findings can guide efforts to refine present methods of patient screening and patient management as practiced by dental students and their preceptors.


Dental education and early careers of Canadian dentists: changes in attitudes, aspirations, and behavior. Longitudinal data on two cohorts of Canadian dental students are examined in order to determine the nature of the changes in attitudes and aspirations which students experience during their undergraduate dental training and the extent to which attitudes and aspirations which students hold on graduation are consistent with subsequent attitudes and behavior in practice. Data are presented on three dimensions of career-related attitudes and behavior: (1) aspirations toward and actual involvement in alternative practice settings, (2) attitudes and behavior related to selected professional and community activities, and (3) attitudes toward specific issues in dentistry. The results indicate that the dental school has little influence on students for the dimensions considered and suggest that analysis of both student backgrounds and the early practice experience of dental graduates may be the key to understanding the career behavior of dental graduates.


Dentists' attitudes toward continuing dental education: nontopic factors of demand for courses. This article reports the results of a survey of dentists' attitudes that influence their demand for continuing education. Unlike the bulk of previous studies, which identified course topics of interest to dentists, this survey investigated attributes of courses unrelated to content. The 1,472 respondents from seven western and mid-western states indicated their attitudes toward mandatory attendance, tuition charges, associated costs, length of course, cancellation policies, reputation of instructor, offerings for auxiliaries, and other attributes of continuing education programs. The findings suggest the need for changes in program management and for further research into factors unrelated to course content that influence demand for dental continuing education courses.


Eliminating some unexpected effects of the dental student admission process. The admission process has long emphasized criteria which ensure successful completion of dental school and licensing requirements. However, little attention has been paid to the long term career consequences of the process and the effects on the present and the future delivery of dental service. In view of changing demands for dental services, an effort is made to encourage dental school faculties to consider the consequences of their continued adherence to traditional approaches to admission.


Convergent evidence for the effectiveness of interpersonal skill training for dental students. The Florida Interpersonal Skills Training (FIST) program for dental students has been evolving for five years. This current paper describes the development and current status of the FIST program and several pieces of evidence that indicate that the program is having its desired effect. This evidence includes (1) demonstration of short-term change in the chairside behavior of students exposed to FIST, (2) more favorable patient perceptions of dentists who behave in accordance with FIST principles (an analog study), (3) student evaluation of the course employing FIST, and (4) practicing dentists' and auxiliaries' evaluation of the usefulness of the course content. It is concluded both that the course seems to be effective and that the evaluation procedures used are both practical and useful.


Predicting clinical performance: a two-step approach. This paper presents the results of a two-year study on the predictive value of the Spatial Relations Test of the Differential Aptitude Test (SRTDAT) for grades in dental hygiene laboratory and clinical courses. The data indicate the SRTDAT was a statistically significant predictor of early laboratory product performance, and this performance was predictive of final clinical performance.


Criterion-oriented grading system for preclinical operative dentistry laboratory course. The object of this study was to evaluate instructor reliabilities when using empirical or traditional and criterion-oriented grading methods. To do so, 52 sample preparations made in plastic teeth by freshman dental students in the preclinical operative dentistry laboratory course were graded by 12 instructors. The preparations included those for amalgam, inlay, and gold foil restorations. The instructors were divided into two groups according to their teaching experience. Intraclass correlation coefficients were calculated by using a one way analysis of variance technique. The criterion method, in general, yielded greater intraclass correlation coefficients. The increase in the intraclass correlation coefficient was found to be significant at the alpha = 0.10 error level for all restorations judged by experienced instructors. The different degrees of increase in correlation may be attributed to the vary ing clinical biases of the instructors and the differences in the types of preparations.


The teaching of forensic dentistry: a status report. A survey was conducted to assess the current status of instruction and curricular content in forensic dentistry in United States dental schools. The dean of each of the 60 dental schools was asked to describe the formal teaching program in forensic dentistry in the predoctoral, postgraduate, resident, and continuing education curriculum. Faculty characteristics and the relationship of the faculty to extramural organizations dealing with forensic science were analyzed. Results indicate that 42 percent of the respondents do not offer formal courses in forensic dentistry at any level of dental education. The remaining 58 percent offer courses that are primarily didactic in nature. The diagnostic dental science departments are responsible for the organization and administration of forensic dental courses at the majority of respondent schools. A significant number of faculty teaching forensic dentistry hold advanced degrees in medicine and law, as well as other disciplines. Although forensic dental faculty are trained to assist law enforcement agencies, their consulting services are not generally used to the fullest extent. Based on the results of this survey, a series of recommendations for structuring the forensic science curriculum in dental schools is offered.


Physical evaluation of the dental patient: current practices and opinions. A survey of 560 graduates of the University of Kentucky College of Dentistry was performed to document the current methods of physical evaluation used by a group of practicing dentists and to sample their opinions about potential additions to the dental curriculum in physical evaluation, as advocated by the Council on Dental Education. The questionnaire was completed and returned by 59 percent of the practitioners. The results indicated that physical evaluation of dental patients was done primarily by using the medical history. Examination of blood pressure, other vital signs, and the head and neck were done infrequently. The clinical laboratory was reportedly utilized frequently. The respondents' attitudes were ones of general support for increasing the emphasis on physical evaluation in dentistry, but with varying opinions about appropriateness.


Study of a classification of occlusion.

Study of a classification of occlusion. A functional classification of occlusion based on the sounds produced by tooth contact was first proposed in 1970. The classification was found useful for identifying patients prone to gnathic dysfunctions as a significantly higher proportion of these patients were in Class C than in Class A. In the studies described in this paper other parameters of occlusion were measured to find if there were differences between the classes in addition to the differences in occlusal sound duration which identified the classes. The first study found highly significant differences in co-ordination between Class A and Class C as measured by the coincidence of sound patterns. Many significant differences at the 1% level were found in the F test of samples of 5 successive occlusal sounds in series of 25 sounds in Classes A and C, but these differences diminished as the series of sounds was prolonged, suggesting that the subject's ability to find stable occlusal positions improved with successive occlusal contacts. No significant differences were found in time intervals between the sounds in different classes, but significant differences were found in masseter muscle activity in relation to the presence or absence of silent periods between occlusal classes. It was concluded that the functional classification of occlusion based on the duration of tooth contact sounds was valid.


Tissue hypersensitivity to dental materials. Five cases of tissue hypersensitivity to Scutan and two to Impregum are reported. The reaction to Scutan was a burning sensation in the mucosa in contact with the material, followed by swelling and erythematous ulcers producing heavy discomfort. All symptoms gradually disappeared after removal of the material. To Impregum the reaction was basically the same, only less vigorous since contact with the material is of limited duration. All the cases were women in the menopause. Attention is drawn to the possibility of hormonal imbalance being a factor of importance in the development of hypersensitivity reactions to materials of this sort.


Viscoelastic properties of elastomeric impression materials: polysulphide, silicone and polyether rubbers. Creep compliance measurements were shown to be effective in characterizing the elastic, retarded elastic, and viscous properties of polysulphide, silicone, and polyether impression materials. The test is particularly valuable in that the creep compliance was independent of load, allowing the mechanical properties to be represented by a single total creep compliance curve which can be used to determine the various creep components. The total recovered compliance was shown to be independent of time provided the polymerization had progressed sufficiently before testing was done. The retarded elastic and viscous compliances contributed proportionally to the total creep compliance and thus did not affect the rankings of materials. The viscous compliance of polysulphide A decreased enough after 1 h so that the creep compliance of A and D were not different. The creep compliance measurements showed that the polysulphide materials were the most viscoelastic followed by silicone and polyether impression materials. The polyether was the most nearly ideal elastic material but it had a flexibility comparable to heavy body polysulphide. Of particular interest was the observation that polyether with thinner in ratios up to 1 : 1 by length had no practical effect on the viscoelastic properties.


A study of temperature changes occurring in setting dental cements. A study has been made of the rise in temperature associated with the setting of dental cements. Results are discussed in terms of the chemistry of the cement systems and are related to specification testing and clinical usage. Zinc oxide cements evolve more heat than those based on ion-leachable glasses, and phosphate bonded cements evolve more heat than polycarboxylate cements.


Dynamic and static recordings of the comfortable zone. A dynamic and a static method of assessing the comfortable zone by means of a screw jack were compared in 12 subjects. Recorded under dynamic conditions the average width of the comfortable zone was approximately 3.0 mm, and under static conditions approximately 5.0 mm (P less than 0.0001). It is suggested that in the dynamic experiments the larger output from receptors in the chewing system was responsible for the narrower zone, i.e. the more precise assessments of the comfortable zone.


Effect of the curing cycle on some properties of a polymethylmethacrylate denture base material. The properties of a denture base material may be modified by altering both the temperature and the time of heating during the curing cycle. In this study a polymethylmethacrylate denture base containing no crosslinking agent was polymerised using four different curing cycles. The structure of the materials so obtained was investigated by an acid etching technique. The materials were characterized with respect to degree of cure, strength and water sorption. It was concluded that: 1. No correlation was observed between the curing cycles and polymer structure. 2. The curing cycle of 7 h at 70 degrees C plus 1 h at 100 degrees C produced best indentation strength and tensile strength. 3. A correlation was observed between residual monomer, indentation resistance, tensile strength and water sorption. This suggested that residual monomer concentration is the most important parameter in the determination of the properties of the material investigated in this study.


Effects of intermaxillary elastic traction on orthodontic tooth movement. Intermaxillary elastics are commonly used in orthodontic treatment, yet the exact mechanism by which they effect tooth movement has been unclear. A photoelastic model was produced to stimulate this type of therapy in examples of Class II and III malocclusions. In the open situation, inter-arch activity precipitated occlusal plane rotation; counter clockwise in Class II malocclusion and clockwise in Class III. Comment is made on the force vectors involved when using intermaxillary elastics.


The clinical significance of median occlusal position. The harmony of the occlusal components of the teeth, mandibular joint and muscles, were investigated in 180 human subjects by clinical, dental articulator, radiographic and electrodiagnostic methods. Significant correlations were found between disharmony of these components at median occlusal position (MOP), and with pain-dysfunction of the masticatory system. Using the standardized stimuli of opening the jaw wide and snapping it shut automatically into MOP, temporalis and masseter muscle co-ordination and somesthetic reflex effects were quantified. The interval from tooth contact (s) to reinstitution of EMG activity (x), and the EMG silent-period duration (SP), were prolonged in the patients but returned to within the control range with elimination of the pain-dysfunction. Muscle incoordination with mandibular dysfunction was prevalent in the patients, and the incidence of osteoarthritis was greatest in those with persistent symptoms. The hypothesis was supported that disharmony of MOP exists in pain-dysfunction patients--while successful occlusal therapy leads to the restoration of the harmony within the biologic range. This implies physiological significance to this hitherto clinically neglected occlusal position.


Microhardness studies on the setting characteristics of fissure sealants. The hardness of five fissure sealants was measured using a Wallace Microhardness Tester and found to continue to increase long after the initial setting. The effect of the intensity of radiation and exposure time on the setting of two u.v. activated sealants (Nuva-seal and Alphaseal) was also investigated, with higher intensities producing both a more rapid set and greater final hardness. Alphaseal required longer exposure at a given intensity of u.v. radiation to achieve the same hardness as Nuva-seal, and displayed relatively slow setting in depth, which could give rise to incomplete polymerization during clinical use, resulting in early sealant loss. Thus special care must be taken to ensure that Alphaseal receives an adequate exposure to u.v. radiation, and sources which are suitable for setting Nuva-seal may not be sufficiently powerful when applying Alphaseal.