interacts_with DB00991?
Microglial activation , increased P01375 and P31645 expression in the prefrontal cortex define stress-altered behaviour in mice susceptible to anhedonia . A chronic stress paradigm comprising exposure to predation , tail suspension and restraint induces a depressive syndrome in C57BL/6J mice that occurs in some , but not all , animals . Here , we sought to extend our behavioural studies to investigate how susceptibility ( sucrose preference < 65 % ) or resilience ( sucrose preference > 65 % ) to stress-induced anhedonia affects the 5HT system and the expression of inflammation-related genes . All chronically stressed animals , displayed increased level of anxiety , but susceptible mice exhibited an increased propensity to float in the forced swim test and demonstrate hyperactivity under stressful lighting conditions . These changes were not present in resilient or acutely stressed animals . Compared to resilient animals , susceptible mice showed elevated expression of tumour necrosis factor alpha ( P01375 ) and the 5-HT transporter ( P31645 ) in the pre-frontal area . Enhanced expression of 5HT(2A) and P23219 in the pre-frontal area was observed in all stressed animals . In turn , indoleamine-2,3-dioxygenase ( P14902 ) was significantly unregulated in the raphe of susceptible animals . At the cellular level , increased numbers of Iba-1-positive microglial cells were also present in the prefrontal area of susceptible animals compared to resilient animals . Consequently , the susceptible animals display a unique molecular profile when compared to resilient , but anxious , animals . Unexpectedly , this altered profile provides a rationale for exploring anti-inflammatory , and possibly , P01375 -targeted therapy for major depression . DB00991 : kinetic and dynamic profile in the treatment of pain . DB00991 ( 4,5-diphenyl-2-oxazolepropionic acid ) is a non-steroidal anti-inflammatory drug ( NSAID ) which is effective in models of inflammation , pain and pyrexia . It is effective and well tolerated in the clinical management of adult rheumatoid arthritis ( RA ) , osteoarthritis ( OA ) , ankylosing spondylitis , soft tissue disorders and post operative dental pain . DB00991 has a high oral bioavailability ( 95 % ) , with peak plasma concentrations at 3 to 5 hours after dosing . It is metabolised in the liver by oxidative and conjugative pathways and readily eliminated by the renal and faecal routes . DB00991 's strong analgesic qualities are particularly useful in painful musculoskeletal conditions such as periarthritis of the shoulder , since it exhibits actions such as inhibition of P23219 and P35354 isoenzymes , inhibition of nuclear translocation of NF-kappaB and of metalloproteases , and modulates the endogenous cannabinoid system . This editorial addresses the accompanying paper by Barbara Heller and Rosanna Tarricone on the management of shoulder periarthritis pain , in which they studied the efficacy and safety of oxaprozin compared to the comparator drug diclofenac over a 15 day period . Both oxaprozin and diclofenac compared well in the primary study endpoint of reduction in shoulder pain . DB00991 and diclofenac were well tolerated and oxaprozin showed better improvement in shoulder function and in the mental health item of the SF-36 quality of life component . The study by Heller and Tarricone is an addition to the large number of clinical trials which demonstrate that oxaprozin has equal efficacy in comparison with standard doses of commonly used anti-rheumatic agents such as aspirin , diclofenac , ibuprofen , indomethacin etc. in several different painful musculoskeletal conditions . Critical role of P21453 and integrin β4 in P14210 /c- DB00134 -mediated increases in vascular integrity . Vascular endothelial cell ( EC ) barrier integrity is critical to vessel homeostasis whereas barrier dysfunction is a key feature of inflammatory disorders and tumor angiogenesis . We previously reported that hepatocyte growth factor ( P14210 ) -mediated increases in EC barrier integrity are signaled through a dynamic complex present in lipid rafts involving its receptor , c- DB00134 . We extended these observations to confirm that P21453 ( sphingosine 1-phosphate receptor 1 ) and integrin β4 ( P16144 ) are essential participants in P14210 -induced EC barrier enhancement . Immunoprecipitation experiments demonstrated P14210 -mediated recruitment of c- DB00134 , P16144 and P21453 to caveolin-enriched lipid rafts in human lung EC with direct interactions of c- DB00134 with both P21453 and P16144 accompanied by c- DB00134 -dependent P21453 and P16144 transactivation . Reduced P21453 expression ( siRNA ) attenuated both P16144 and Rac1 activation as well as c- DB00134 / P16144 interaction and resulted in decreased transendothelial electrical resistance . Furthermore , reduced P16144 expression attenuated P14210 -induced c- DB00134 activation , c- DB00134 / P21453 interaction , and effected decreases in Q14703 - and P14210 -induced EC barrier enhancement . Finally , the c- DB00134 inhibitor , DB05030 , suppressed P14210 -induced c- DB00134 activation as well as P21453 and P16144 transactivation . These results support a critical role for P21453 and P16144 transactivation as rate-limiting events in the transduction of P14210 signals via a dynamic c- DB00134 complex resulting in enhanced EC barrier integrity . Recombinant human P05155 for the treatment of hereditary angioedema due to C1 inhibitor deficiency ( DB05341 -HAE ) . The lack of C1 inhibitor function that results in excessive production of bradykinin causing the angioedema seen in hereditary angioedema ( HAE ) is well established . Several drugs have been developed to treat and prevent attacks in patients suffering from HAE due to C1 inhibitor deficiency ( DB05341 -HAE ) . Plasma-derived C1INH has been used to replace the deficiency of C1 inhibitor ( C1INH ) and has been approved for both treatment of attacks and for prophylactic therapy to prevent attacks . P03952 inhibitor ( ecallantide ) and bradykinin receptor antagonist ( icatibant ) are both effective for treatment of acute attacks , but their short half-life limits the use for prophylaxis . Androgens , in particular danazol , are effective for long-term prophylaxis , but adverse event profile can limit its use . Recombinant C1 inhibitor derived from transgenic rabbits has recently been approved for use in treatment of DB05341 -HAE attacks and is effective and appears safe with minimal adverse event profile . Prostaglandin synthase 2/cyclooxygenase 2 ( P35354 / P35354 ) 8473T > C polymorphism associated with prognosis for patients with colorectal cancer treated with capecitabine and oxaliplatin . PURPOSE : The present study analyzed the polymorphisms of apoptosis-related genes and their impact on the response to chemotherapy and survival of patients with colorectal cancer . PATIENTS AND METHODS : A total of 76 patients with recurrent or metastatic colorectal cancer treated with capecitabine and oxaliplatin ( XELOX ) combination chemotherapy were enrolled in the present study . The single nucleotide polymorphisms of 15 apoptosis-related genes ( P04637 , Q07817 , O14763 , P31749 , P35354 / P35354 , P55957 , Q13546 , FAS , P48023 , caspase 3 , and caspase 6-10 ) were determined using a PCR-RFLP assay . RESULTS : No significant association between the polymorphisms and the response was found for any of the genes analyzed . However , the T/T genotype of P35354 8473T > C ( rs5275 ) was significantly correlated with a better progression-free survival ( PFS ) and overall survival ( OS ) when compared to the combined T/C and C/C genotype ( Hazard ratio [ HR ] = 0.47 ; P value = 0.046 and HR = 0.16 ; P = 0.013 , respectively ) in a multivariate analysis adjusted for age , sex , performance status , disease status and curative resection . No association was noted between the other polymorphisms and survival . CONCLUSION : The P35354 8473T > C polymorphism was found to be correlated with PFS and OS in patients with advanced colorectal cancer treated with XELOX chemotherapy . Antihistamine effects on prefrontal cortex activity during working memory process in preschool children : a near-infrared spectroscopy ( NIRS ) study . P35367 antagonists ( antihistamines ) are widely used for the treatment of allergic disorders in young children . This study examined the effects of antihistamine on prefrontal cortex activity in preschool children using near-infrared spectroscopy ( NIRS ) , an emerging brain-imaging method suitable for psychological experiments , especially in young children . We examined the changes of oxygenated hemoglobin concentration in the prefrontal cortex while children performed a spatial working memory task , 3h after taking a first-generation antihistamine ( ketotifen ) , second-generation antihistamine ( epinastine ) , or placebo . Fifteen healthy preschool children ( mean age , 5.5 years ) participated . DB00920 significantly impaired behavioral performance and cortical activation at the lateral prefrontal cortex in the working memory task , compared with epinastine and placebo . There were no sedative effects on neural response or behavioral performance after epinastine administration . This paper demonstrates for the first time differential sedation effects of first- and second-generation antihistamines on brain hemodynamic response in young children . Also discussed is the utility of the NIRS technique in neuropsychopharmacological studies of children . Suppression of inducible cyclooxygenase 2 gene transcription by aspirin and sodium salicylate . The pharmacological action of salicylate can not be explained by its inhibition of cyclooxygenase ( P36551 ) activity . In this report , the effects of aspirin and sodium salicylate on P35354 expressions in human umbilical vein endothelial cells and foreskin fibroblasts were evaluated . DB00945 and sodium salicylate at therapeutic concentrations equipotently blocked P35354 mRNA and protein levels induced by interleukin-1beta and phorbol 12-myristate 13-acetate . The suppressing effect was more pronounced in cultured cells deprived of fetal bovine serum for 24 h , suggesting that it may be cell cycle related . Salicylate inhibited nascent P35354 transcript synthesis but had no effect on P35354 mRNA stability . It inhibited P35354 promoter activity in a concentration-dependent manner . In mice pretreated with aspirin ( 10 and 30 mg/kg ) , followed by challenge with lipopolysaccharide , P35354 mRNA expression in peritoneal macrophages was markedly suppressed . These findings suggest that salicylate exerts its antiinflammatory action in part by suppressing P35354 induction , thereby reducing the synthesis of proinflammatory prostaglandins . Genetically rescued tetrahydrobiopterin-depleted mice survive with hyperphenylalaninemia and region-specific monoaminergic abnormalities . One of the possibly mutated genes in DOPA-responsive dystonia ( DRD , Segawa 's disease ) is the gene encoding P30793 , which is the rate-limiting enzyme for tetrahydrobiopterin ( BH4 ) biosynthesis . Based on our findings on 6-pyruvoyltetrahydropterin synthase ( Q03393 ) gene-disrupted ( Pts(-/-) ) mice , we suggested that the amount of tyrosine hydroxylase ( TH ) protein in dopaminergic nerve terminals is regulated by the intracellular concentration of BH4 . In this present work , we rescued Pts(-/-) mice by transgenic introduction of human Q03393 cDNA under the control of the dopamine beta-hydroxylase promoter to examine regional differences in the sensitivity of dopaminergic neurons to BH4-insufficiency . The DPS-rescued ( Pts(-/-) , DPS ) mice showed severe hyperphenylalaninemia . Human Q03393 was efficiently expressed in noradrenergic regions but only in a small number of dopaminergic neurons . DB03886 and dopamine contents , and TH activity in the striatum were poorly restored compared with those in the midbrain . TH-immunoreactivity in the lateral region of the striatum was far weaker than that in the medial region or in the nucleus accumbens . We concluded that dopaminergic nerve terminals projecting to the lateral region of the striatum are the most sensitive to BH4-insufficiency . Biochemical and pathological changes in DPS-rescued mice were similar to those in human malignant hyperphenylalaninemia and DRD . Enhanced uridine adenosine tetraphosphate-induced contraction in renal artery from type 2 diabetic Goto-Kakizaki rats due to activated cyclooxygenase/thromboxane receptor axis . The dinucleotide uridine adenosine tetraphosphate ( Up4A ) , which has both purine and pyrimidine moieties , was reported as a novel endothelium-derived contracting factor . Recently , growing evidence has suggested that Up4A plays an important role in regulation of the cardiovascular function . We previously demonstrated that Up4A-induced vasoconstrictions are altered in arteries from DOCA-salt hypertensive rats . We have assessed responses to Up4A shown by renal arteries from type 2 diabetic Goto-Kakizaki ( GK ) rats ( 42-46 weeks old ) and identified the molecular mechanisms involved . Concentration-dependent contractions to Up4A were greater in renal arterial rings from the GK than age-matched control Wistar group . In both groups , the inhibition of nitric oxide synthase ( with N ( G ) -nitro-L-arginine ) increased the response to Up4A , whereas the inhibition of cyclooxygenase ( P36551 ) ( with indomethacin ) decreased the response . Specific inhibitors of P23219 ( valeroyl salicylate ) and P35354 ( NS398 ) , a thromboxane ( TX ) receptor ( TP ) antagonist ( SQ29548 ) , and P2 receptor antagonist ( suramin ) also decreased the response to Up4A . Protein expressions of COXs in renal arteries were greater in the GK than Wistar group . The production of TXB2 ( a metabolite of TXA2 ) by Up4A did not differ between these groups . Concentration-dependent contractions to U46619 , an agonist of the TP receptor , were greater in renal arteries from the GK than Wistar group . The expression of P51575 and P41231 receptors did not differ between these groups . These results suggest that enhancement of the Up4A-induced contraction in renal arteries from GK rats may be attributable to the increased activation of COXs/TP receptor signaling . Altered regulation of renal nitric oxide , atrial natriuretic peptide and cyclooxygenase systems in aldosterone escape in rats . The present study was aimed to determine whether there is an altered role of local nitric oxide ( NO ) , atrial natriuretic peptide ( P01160 ) and cyclooxygenase ( P36551 ) systems in the kidney in association with the aldosterone escape . Male Sprague-Dawley rats were used . DB04630 ( 200 microg/day ) was infused through entire time course . The control group was kept on a low sodium diet ( 0.02 mEq/day ) , and the experimental group was supplied with a higher sodium diet ( 2. /day ) . Four days after beginning the regimen , the kidneys were taken . The protein expression of NO synthase ( NOS ) and P36551 isoforms was determined by semiquantitative immunoblotting . The mRNA expression of components of P01160 system was determined by real-time polymerase chain reaction . The activities of soluble and particulate guanylyl cyclases were determined by the amount of cGMP generated in responses to sodium nitroprusside and P01160 , respectively . There developed aldosterone escape in the experimental group . Accordingly , the renal content and the urinary excretion of NO increased . The expression of P29475 was increased in the inner medulla . Neither the expression of P29474 nor that of P35228 was changed . The expression and the catalytic activity of soluble guanylyl cyclase remained unaltered . The mRNA expression of P01160 was increased . Neither the expression of P16066 or P17342 nor the activity of particulate guanylyl cyclase was altered in the papilla . The protein expression of P35354 was increased in the inner medulla , while that of P23219 remained unchanged . In conclusion , the upregulation of P29475 , P01160 , and P35354 may be causally related with the aldosterone escape . Genetic mechanism of aspirin-induced urticaria/angioedema . PURPOSE OF REVIEW : DB00945 -induced urticaria/angioedema is a major aspirin-related hypersensitivity often associated with aspirin-intolerant asthma . Genetic studies on aspirin-intolerant asthma have shown chronic overproduction of cysteinyl leukotrienes . The genetic analysis of aspirin-induced urticaria/angioedema is limited , however . RECENT FINDINGS : A recent study on HLA genotypes has suggested that the HLA alleles DRB11302 and DQB10609 may be genetic markers for aspirin-induced urticaria/angioedema . A polymorphism study that examined nine single-nucleotide polymorphisms of five leukotriene-related genes [ P09917 ( encoding P09917 ) , P20292 ( P09917 -activating protein ) , P35354 ( cyclooxygenase 2 ) , Q16873 ( leukotriene C4 synthase ) , and Q9Y271 ( cysteinyl leukotriene receptor 1 ) ] found that promoter polymorphisms of P09917 ( -1708A > G ) and Q9Y271 ( -634C > T ) were significantly different between aspirin-intolerant asthma and aspirin-induced urticaria/angioedema , suggesting different contributions to the lipoxygenase pathway . A second polymorphism study , conducted on histamine-related genes , did not find any significant associations with aspirin-induced urticaria/angioedema for the genes P50135 ( encoding histamine N-methyltransferase ) , P35367 or P25021 ( encoding histamine receptor types 1 and 2 respectively ) , or the gene encoding high-affinity IgE receptor Ibeta ( FcepsilonRIbeta ) ; however , the FcepsilonRIalpha gene promoter polymorphism was significantly associated with aspirin-induced urticaria/angioedema . This finding has been supported by in vitro functional studies . SUMMARY : The HLA alleles DRB11302 and DQB10609 , and the P09917 and FcepsilonRIalpha promoter polymorphisms , may contribute to the pathogenesis of aspirin-induced urticaria/angioedema . Further investigation to identify candidate genetic markers would help to elucidate the pathogenic mechanism of this condition . Protein kinase C-associated kinase regulates NF-κB activation through inducing IKK activation . Activation of the transcription factor NF-κB induced by extracellular stimuli requires IKKα and IKKβ kinase activity . How IKKα and IKKβ are activated by various upstream signaling molecules is not fully understood . We previously showed that protein kinase C-associated kinase ( P03952 , also known as P57078 /RIP4 ) , which belongs to the receptor-interacting protein ( RIP ) kinase family , mediates the B cell activating factor of the P01375 family ( Q9Y275 ) -induced NF-κB activation in diffuse large B cell lymphoma ( DLBCL ) cell lines . Here we have investigated the mechanism underlying NF-κB activation regulated by P03952 . Our results suggest that P03952 can activate both the classical and the alternative NF-κB activation pathways . P03952 associates with IKKα and IKKβ in mammalian cells and induces activation of both IKKα and IKKβ via phosphorylation of their serine residues 176/180 and 177/181 , respectively . Unlike other members of the RIP family that activate NF-κB through a kinase-independent pathway , P03952 appears to activate IKK and NF-κB mainly in a kinase-dependent manner . Suppression of P03952 expression by RNA interference inhibits phosphorylation of IKKα and IKKβ as well as activation of NF-κB in human cancer cell lines . Thus , P03952 regulates NF-κB activation by modulating activation of IKKα and IKKβ in mammalian cells . We propose that P03952 may provide a critical link between IKK activation and various upstream signaling cascades , and may represent a potential target for inhibiting abnormal NF-κB activation in human cancers . The effects of DB05294 , an inhibitor of P15692 signaling , on cutaneous wound healing in mice . BACKGROUND : DB05294 is an inhibitor of the P35968 receptor tyrosine kinase with additional activity against P00533 -1 receptor tyrosine kinases that has been shown to inhibit tumor growth and wound-induced neovascularization in pre-clinical studies and phase I clinical trials . The purpose of this study was to determine the effects of DB05294 on breaking strength in a murine model of cutaneous wound healing . MATERIALS AND METHODS : Balb/C mice were given DB05294 ( 50 or 100 mg/kg p.o. ) or vehicle starting 7 days before wounding . Two full-thickness incisions were made in each mouse and closed using suture . On post-wounding day 7 or 28 , laser Doppler blood flow measurements were made , and the breaking strength of the wounded skin was determined . Microvessel density measurements were performed using computer image analysis of CD31-stained sections . RESULTS : Compared with controls , mice treated with DB05294 showed a significantly reduced dose-dependent decline in breaking strength , both at POD 7 ( P < 0.001 ) and at POD 28 ( P < 0.005 ) . Histologically , the DB05294 -treated mice showed a qualitative reduction in the degree of fibrosis and epithelial proliferation at the wound site , but no significant difference was noted between the 50 mg/kg and 100 mg/kg DB05294 -treated groups . Also , microvessel density measurements demonstrated no significant difference between groups . CONCLUSION : In a murine model of wound healing , DB05294 treatment did not prevent wound healing , but was associated with a reduced skin breaking strength compared with vehicle-treated controls at both 7 and 28 days post-wounding . These observations may have clinical relevance for the perioperative management of patients treated with inhibitors of angiogenesis . Growth factors expression in patients with erosive esophagitis . Although the pathogenesis and treatment of erosive esophagitis ( EE ) is well recognized , little is known about the cellular and molecular mechanisms of mucosal healing in EE patients . In this pilot study , we enrolled typical EE patients to evaluate what kinds of growth factors and their receptors were activated in their injured esophageal mucosa . Forty endoscopically proved EE patients were consecutively enrolled . Messenger RNA expressions , which includes keratinocyte growth factor ( KGF ) and its receptor ( P21802 ) , epidermal growth factor ( P01133 ) and its receptor ( P00533 ) , hepatocyte growth factor ( P14210 ) and its receptor ( HGFR ) , basic fibroblast growth factor ( P09038 ) , vascular endothelial growth factor ( P15692 ) , and cyclooxygenase ( P36551 ) -1 and P35354 , were measured using real-time polymerase chain reaction ( PCR ) . Data were compared between the injured EE mucosa and their normal esophageal mucosa above EE . The mRNA expressions of P14210 , HGFR , P01133 , P15692 , and P35354 , but not P00533 , KGF , P21802 , P09038 , and P23219 , were significantly increased in the injured mucosa of EE patients compared with those of normal mucosa ( P < 0.05 ) . The study found that P14210 , HGFR , P01133 , P15692 , and , P35354 are activated in the injured mucosa of EE patients ; their activation might be involved in mucosal repair and ulcer healing of EE . Ca2+ response of rat mesangial cells to DB00171 analogues . The aim of this investigation was to characterise the effects of DB00171 analogues and UTP on the single cell intracellular Ca2+ concentration ( [Ca2+]i ) in cultured rat mesangial cells . Typically , there were two phases in the Ca2+ response to the agonists , an initial fast transient peak and a subsequent slower decline , or plateau , phase . For the peak amplitude in [Ca2+]i the agonists had about equal effect . But when taking in consideration the percentage of responding cells and the integrated Ca2+ response over 1 min , the order of efficacy of nucleotide agonists ( 100 microM ) was UTP = DB00171 > ATPgammaS > ADP = 2MeS- DB00171 ( 2-methylthio- DB00171 ) . DB00640 , AMP and beta,gamma-Me- DB00171 ( 100 microM ) had no effect . DB04786 ( 100 microM ) and reactive blue ( 50 microM ) decreased the number of responding cells . Removing Ca2+ from the bath diminished neither the peak in [Ca2+]i nor the percentage of responding cells , but the average [Ca2+]i increase in 1 min was significantly reduced . The results indicate that P41231 receptors are present in rat mesangial cells but it can not be excluded that there are receptors distinct from P41231 which also mediate a rise in [Ca2+]i . Mutational analysis of the mitochondrial P47985 of Saccharomyces cerevisiae . II . Biochemical characterization of temperature-sensitive Q13546 - mutations . Although the function of the P47985 is generally understood , little is known of how the structure of this protein supports its mechanistic role in electron transfer in the cytochrome bc1 complex . To better understand the structural basis of iron-sulfur protein function , we have undertaken a mutational analysis of the gene encoding this protein and initially isolated five temperature-sensitive iron-sulfur protein mutants ( Beckmann , J. D. , Ljungdahl , P. O. , and Trumpower , B. L. ( 1989 ) J. Biol. Chem. 264 , 3713-3722 ) . Each of the five ts-rip1- mutants exhibited pleiotropic effects . Although the mutant iron-sulfur proteins manifest several in vitro phenotypes in common , each exhibited unique characteristics . All of the ts-rip1- mutations resulted in membranes with decreased ubiquinol-cytochrome c oxidoreductase activities and decreased thermostability compared to membranes containing wild type iron-sulfur protein . All of the mutations conferred slight but significant resistance to the respiratory inhibitor myxothiazol , and one mutant was hypersensitive to inhibition by DB04799 , a structural analog of ubiquinone . In addition , one of the mutations completely blocks post-translational processing of the iron-sulfur protein , leading to accumulation of pre-iron-sulfur protein in mitochondrial membranes at nonpermissive temperatures . Finally , a mutation 12-amino acid residues away from the carboxyl terminus ( 203S ) results in an extremely unstable protein . This region of the protein may be essential in blocking degradation of pre-iron-sulfur protein by cytoplasmic proteases as the protein is imported into the mitochondria , or may be a " degradation signal , " which tags the iron-sulfur protein for turnover . Involvement of sphingosine kinase in P01375 -stimulated tetrahydrobiopterin biosynthesis in P13671 glioma cells . In P13671 glioma cells , the sphingolipid second messenger ceramide potentiates expression of inducible nitric-oxide synthase ( P35228 ) induced by tumor necrosis factor alpha ( P01375 ) without affecting P30793 ( GTPCH ) , the rate-limiting enzyme in the biosynthesis of 6(R)- DB00360 ( BH(4) ) , a cofactor required for P35228 activity . P01375 also stimulates sphingosine kinase , the enzyme that phosphorylates sphingosine to form sphingosine-1-phosphate ( Q8TCT9 ) , a further metabolite of ceramide . Several clones of P13671 cells , expressing widely varying levels of sphingosine kinase , were used to examine the role of Q8TCT9 in regulation of GTPCH and BH(4) biosynthesis . Overexpression of sphingosine kinase , with concomitant increased endogenous Q8TCT9 levels , potentiated the effect of P01375 on GTPCH expression and activity and BH(4) biosynthesis . In contrast , enforced expression of sphingosine kinase had no effect on P35228 expression or NO formation . Furthermore , N,N-dimethylsphingosine , a potent sphingosine kinase inhibitor , completely eliminated the increased GTPCH activity and expression induced by P01375 . Surprisingly , we found that , although P13671 cells can secrete Q8TCT9 , which is enhanced by P01375 , treatment of P13671 cells with exogenous Q8TCT9 or dihydro- Q8TCT9 had no affect on BH(4) biosynthesis . However , both Q8TCT9 and dihydro- Q8TCT9 markedly stimulated P29323 1/2 in P13671 cells , which express cell surface Q8TCT9 receptors . Interestingly , although this P29323 activation was blocked by PD98059 , which also reduced cellular proliferation induced by enforced expression of sphingosine kinase , PD98059 had no effect on GTPCH activity . Collectively , these results suggest that only intracellularly generated Q8TCT9 plays a role in regulation of GTPCH and BH(4) levels . The L-arginine paradox : Importance of the L-arginine/asymmetrical dimethylarginine ratio . Cardiovascular diseases ( CVD ) are still the most frequent cause of death in Western Europe . Pathophysiological experiments revealed in the last years that the vascular endothelium , as well as a result of the synthesis of nitric oxide ( NO ) , is a crucial regulator of vascular function and homeostasis . The vascular endothelium plays a key role in cardiovascular physiology and pathophysiology , largely via NO-dependent processes . L- DB00125 is the substrate for the endothelial NO synthase ( P29474 ) to generate NO . Endothelial dysfunction is caused by various cardiovascular risk factors . In most studies , acute and chronic administration of L-arginine has been shown to improve endothelial function in animal models of hypercholesterolemia and atherosclerosis . Therefore , numerous studies have been conducted to elucidate whether dietary L-arginine supplementation can augment NO production in humans and thereby improve endothelium-dependent vasodilatation . The most likely mechanism that explains the occurrence of endothelial dysfunction and the effect of L-arginine is that application of L-arginine antagonizes asymmetric dimethylarginine ( DB01686 ) , the endogenous NO synthase ( NOS ) inhibitor . This could solve the L-arginine paradox namely that L-arginine improves NO-mediated vascular function in vivo , although its baseline plasma concentration is about 25- to 30-fold higher than the Michaelis-Menten constant Km of the isolated , purified P29474 in vitro . Recent findings suggest that large , prospective , randomized clinical trials might be needed to identify those patients who are the most likely to benefit from L-arginine . Testing patients for DB01686 and L-arginine plasma levels for calculating the L-arginine/ DB01686 ratio might be an adequate strategy .