Guanine aminohydrolase(GAH;EC 3. 5. 4. 3.) was partially purified 122-fold from rat cerebrum to a specific activity of 7.22 in its per mg protein with a recovery of 7.47% by fractionation with ammonium sulfate, chromatography on DEAE-cellulose and hydroxyapatite, gel filtration on Sephadex G-200, and isoelectric focusing(pH4-6). The molecular weight of partially purified rat cerebral guanine aminohydrolase was estimated to be 110,000. But, in the cerebral cytosol, a rather higher molecular weight form of the enzyme was identified. The activity of the higher molecular weight form of guanine aminohydrolase was increased by dialyzing the cytosol, and it was converted into the lower molecular weight form(M.W.110,000) by addition of 2-mercaptoethanol. The reaction velocity of partially purified guanine aminohydrolase of rat cerebrum disclosed a hyperbolic curve, with its KM being 6.0uM at pH 8.0. The preparation showed high substrate specificity:among the purine nucleotides, nucleosides and bases with amino group, only guanosine and guanine were deaminated by the enzyme, and the reaction rate of the enzyme displayed by guanosine was less than 10% of that by guanine. When observed under the equimolar concentration of the substrate, hypoxanthine as well as inosine inhibited the activity of the rat cerebral guanine aminohydrolase by 9.4 and 7.8%, respectively, while 5-aminoimidazole-4-carboxamide inhibited the activity of it by 38%. The activity was inhibited by p-hydroxymercuric benzoate as well. Complete loss of its activity was observed after 30 minutes incubation at 60 degrees C, suggesting the preparation was heat labile.
Ammonium Sulfate ; Animals ; Benzoates ; Cerebrum* ; Chromatography ; Chromatography, Gel ; Cytosol ; DEAE-Cellulose ; Durapatite ; Filtration ; Guanine Deaminase* ; Guanine* ; Guanosine ; Hot Temperature ; Hydrogen-Ion Concentration ; Hypoxanthine ; Inosine ; Mercaptoethanol ; Molecular Weight ; Nucleosides ; Purine Nucleotides ; Rats* ; Xanthine Oxidase

BACKGROUND: Myocardial ischemia in human hypertension and in various animal models of hypertension may be due to abnormal maximal coronary vasodilator reserve and disturbaces of coronary vasomotion. The vascular reactivity defects in hypertension have been associated with the defective endothelium and sympathetic neural activation. However, such abnormalities in hypertension need to be elucidated. In the present study the effectsof cardiac ischemia reperfusion on coronary circulation, intramyocytic adenylates and purine nucleosides were examined in Langendorff-perfused Sprague Dawley rat (SD) and spontaneously hypertensive rat (SHR) hearts. Coronary venous and cardiac lactate and cardiac pyruvate were also measured. It should be noted that in the regulation of coronary flow the intrinsic flow autoregulation is highly variable due to coexisting metabolic flow control, and that natural coronary flow and cardiomyocytic energy state are normally reciprocally related in perfused heart. METHODS: For the Langendorff heart perfusion, bicarbonate perfusion buffer (pH 7.40+/-0.02,37degrees C) was equilibrated with 95% O2 : 5% CO2 and contained 5mM glucose (+5U/1 insulin) and 2mM pyruvate as energy-yielding substrates. Global hypoperfusion ischemia was induced by lowering coronary perfusion pressure of 100 to 40 cmH2O, followed by 20 min reperfusion. RESULTS: During the ischemia and reperfusion, metabolic acidosis and enhanced venous lactate output in SHR were observed with increases in coronary vascular resistance and myocardial oxygen consumption.In addition, coronary reactive hyperemia during reperfusion was depressed. Although ischemia-induced increase in combined adenosine plus inosine were abolished during prolonged reperfusion, SD still exhibited coronary vasodilation. The depressed reactive hyperemia in SHR was associated with decreases in cardiac adenosine triphosphate (ATP) pool and creatine phosphate/inorganic phosphate (CrP/Pi) ratio and an increase in cardiac lactate/pyruvate ratio. CONCLUSION: This abnormal vascular reactivity during ischemia and reperfusion in SHR may be in part due to an alteration in the cardiac energy state and hence to a mismatch between myocardial metabolic demand and supply.
Acidosis ; Adenosine ; Adenosine Triphosphate ; Animals ; Coronary Circulation ; Creatine ; Endothelium ; Glucose ; Heart* ; Homeostasis ; Humans ; Hyperemia ; Hypertension ; Inosine ; Ischemia ; Lactic Acid ; Models, Animal ; Myocardial Ischemia ; Oxygen ; Perfusion* ; Purine Nucleosides ; Pyruvic Acid ; Rats ; Rats, Inbred SHR* ; Reperfusion ; Vascular Resistance ; Vasodilation

BACKGROUNDPancreatic cancer is one of the most common tumors and has a 5-year survival for all stages of less than 5%. Most patients with pancreatic cancer are diagnosed at an advanced stage and therefore are not candidates for surgical resection. In recent years, investigation into alternative treatment strategies for this aggressive disease has led to advances in the field of gene therapy for pancreatic cancer. E. coli purine nucleoside phosphorylase/6-methylpurine deoxyribose (ePNP/MePdR) is a suicide gene/prodrug system where PNP enzyme cleaves nontoxic MePdR into cytotoxic membrane-permeable compounds 6-methylpurine (MeP) with high bystander activity. hTERT is expressed in cell lines and tissues for telomerase activity. In this study we examined the efficacy of ePNP under the control of hTERT promoter sequences and assessed the selective killing effects of the ePNP/prodrug MePdR system on pancreatic tumors.

METHODSRecombinant pET-PNP was established. The protein of E. coli PNPase was expressed and an antibody to E. coli PNPase was prepared. Transcriptional activities of hTERT promoter sequences were analyzed using a luciferase reporter gene. A recombinant phTERT-ePNP vector was constructed. The ePNP/MePdR system affects SW1990 human pancreatic cancer cell lines in vitro.

RESULTSThe hTERT promoter had high transcriptional activity and conferred specificity on cancer cell lines. The antibody to E. coli PNPase was demonstrated to be specific for the ePNP protein. The MePdR treatment induced a high in vitro cytotoxicity on the sole hTERT-ePNP-producing cell lines and affected SW1990 cells in a dose-dependent manner.

CONCLUSIONSThe hTERT promoter control of the ePNP/MePdR system can provide a beneficial anti-tumor treatment in pancreatic cancer cell lines including a good bystander killing effect.

Cell Line, Tumor ; Escherichia coli ; enzymology ; Genetic Therapy ; Humans ; Pancreatic Neoplasms ; therapy ; Promoter Regions, Genetic ; Purine Nucleosides ; therapeutic use ; Purine-Nucleoside Phosphorylase ; genetics ; Telomerase ; genetics

During a continuing search for antimicrobial substances from Korean native wild mushroom extracts, we found that the methanolic extract of the fruiting body of Clitocybe nebularis exhibited mild antifungal activity against pathogenic fungi. Therefore we evaluated the antifungal substances and other chemical components of the fruiting body of Clitocybe nebularis, which led to the isolation of nebularine, phenylacetic acid, purine, uridine, adenine, uracil, benzoic acid, and mannitol. Nebularine showed mild antifungal activity against Magnaphorthe grisea and Trichophyton mentagrophytes, and phenylacetic acid potently inhibited the growth of Pythium ultiumand displayed moderate antifungal activity against Magnaphorthe grisea, Botrytis cinerea, and Trichophyton mentagrophytes. The other isolated compounds showed no antimicrobial activity.
Adenine ; Agaricales ; Benzoic Acid ; Botrytis ; Fruit ; Fungi ; Mannitol ; Methanol ; Phenylacetates ; Purine Nucleosides ; Purines ; Pythium ; Ribonucleosides ; Trichophyton ; Uracil ; Uridine

We investigated the effects of dietary folate supplementation on plasma homocysteine, vitamin B12 and hepatic levels of S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) in diet-induced hyperhomocysteinemic rats. All animals were fed 0.3% homocysteine diet for 2 weeks, then they were placed either on a 0.3% homocystine or no homocystine with or without 8 mg/kg folate diet for 8 weeks. Homocystine diet induced hyperhomocysteinemia up to 3.5-fold at 10 weeks (28.0+/-4.8 micromol/l vs. 7.9+/-0.3 micromol/l). Dietary folate supplementation caused a significant decrease in plasma homocysteine levels which had been increased by a homocystine-diet. Also, dietary folate supplementation made them return to control levels at 4 wk when the diet was free of homocystine. Plasma folate levels were markedly decreased with homocystine diet with no folate supplementation. Plasma vitamin B12 did not differ between groups. Dietary homocystine increased hepatic levels of SAM in folate supplementation group at 10 weeks (p<0.05). Dietary folate supplementation increased hepatic levels of SAM/SAH ratios in homocystine group (p<0.05). In conclusion, dietary folate supplementation can effectively ameliorate the detrimental effects of hyperhomocysteinemia.mia.
Animals ; Diet ; Folic Acid* ; Homocysteine ; Homocystine* ; Hyperhomocysteinemia* ; Metabolism* ; Plasma ; Rats* ; S-Adenosylhomocysteine ; S-Adenosylmethionine* ; Vitamin B 12

Adenine ; analogs & derivatives ; chemistry ; pharmacology ; Animals ; Anti-HIV Agents ; chemistry ; pharmacology ; Antiviral Agents ; chemistry ; pharmacology ; Arabinofuranosyluracil ; analogs & derivatives ; chemistry ; pharmacology ; Cytosine ; analogs & derivatives ; chemistry ; pharmacology ; Dioxolanes ; chemistry ; pharmacology ; Humans ; Molecular Structure ; Nucleosides ; chemistry ; pharmacology ; Organophosphonates ; chemistry ; pharmacology ; Purine Nucleosides ; chemistry ; pharmacology ; Tenofovir

OBJECTIVETo establish a quantitative analysis method for analyzing the nucleosides in Cordyceps sinensis with capillary electrophoresis, and compare the difference between natural and the cultured C. mycelia.

METHODCapillary zone electrophoresis method was employed to quantitate the adenosine, uridine, guanosine and inosine in C. sinensis, with 0.25 mg x L(-1) boric acid-sodium hydroxide buffer, pH 9.5. The working voltage was 20 kV, the temperature was 25 degrees C, and the detection wavelength was 260 nm.

RESULTWith the capillary zone electrophoresis method, the average recovery of the above 4 nucleosides was 98.9%, 95.1%, 97.8% and 98.8% respectively, with the RSD 0.4%, 1.7%, 1.3% and 5.0%. There was no adenosine in natural C. sinensis and no inosine in the cultured C. mycelia detected.

CONCLUSIONThis method can be used to determine the adenosine, uridine, guanosine and inosine in C. sinensis. The nucleosides in C. sinensis produced from Qinghai province and cultured C. mycelia are obviously different.

Adenosine ; analysis ; Animals ; Cordyceps ; chemistry ; classification ; Culture Techniques ; Electrophoresis, Capillary ; methods ; Guanosine ; analysis ; Inosine ; analysis ; Lepidoptera ; chemistry ; Uridine ; analysis

Folate is generally considered as a safe water-soluble vitamin for supplementation. However, we do not have enough information to confirm the potential effects and safety of folate supplementation and the interaction with vitamin B12 deficiency. It has been hypothesized that a greater methyl group supply could lead to compensation for vitamin B12 deficiency. On this basis, the present study was conducted to examine the effects of high-dose folic acid (FA) supplementation on biomarkers involved in the methionine cycle in vitamin B12-deficient rats. Sprague-Dawley rats were fed diets containing either 0 or 100 microg (daily dietary requirement) vitamin B12/kg diet with either 2 mg (daily dietary requirement) or 100 mg FA/kg diet for six weeks. Vitamin B12-deficiency resulted in increased plasma homocysteine (p<0.01), which was normalized by dietary supplementation of high-dose FA (p<0.01). However, FA supplementation and vitamin B12 deficiency did not alter hepatic and brain S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) concentrations and hepatic DNA methylation. These results indicated that supplementation of high-dose FA improved homocysteinemia in vitamin B12-deficiency but did not change SAM and SAH, the main biomarkers of methylating reaction.
Animals ; Biomarkers ; Brain ; Compensation and Redress ; Diet ; Dietary Supplements ; DNA Methylation ; Folic Acid ; Homocysteine ; Hyperhomocysteinemia ; Methionine ; Plasma ; Rats ; Rats, Sprague-Dawley ; S-Adenosylhomocysteine ; S-Adenosylmethionine ; Vitamin B 12 Deficiency ; Vitamins

BACKGROUND/OBJECTIVE: The aim of this study was to examine the effect of high dietary methionine (Met) consumption on plasma and hepatic oxidative stress and dyslipidemia in chronic ethanol fed rats. MATERIALS/METHODS: Male Wistar rats were fed control or ethanol-containing liquid diets supplemented without (E group) or with DL-Met at 0.6% (EM1 group) or 0.8% (EM2 group) for five weeks. Plasma aminothiols, lipids, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Hepatic folate, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: DL-Met supplementation was found to increase plasma levels of homocysteine (Hcy), triglyceride (TG), total cholesterol (TC), and MDA compared to rats fed ethanol alone and decrease plasma ALT. However, DL-Met supplementation did not significantly change plasma levels of HDL-cholesterol, cysteine, cysteinylglycine, and glutathione. In addition, DL-Met supplementation increased hepatic levels of folate, SAM, SAH, and SAM:SAH ratio. Our data showed that DL-Met supplementation can increase plasma oxidative stress and atherogenic effects by elevating plasma Hcy, TG, and TC in ethanol-fed rats. CONCLUSION: The present results demonstrate that Met supplementation increases plasma oxidative stress and atherogenic effects by inducing dyslipidemia and hyperhomocysteinemia in ethanol-fed rats.
Alanine Transaminase ; Animals ; Aspartate Aminotransferases ; Cholesterol ; Cysteine ; Diet ; Dyslipidemias* ; Ethanol ; Folic Acid ; Glutathione ; Homocysteine ; Humans ; Hyperhomocysteinemia ; Male ; Malondialdehyde ; Methionine* ; Oxidative Stress* ; Plasma ; Rats* ; Rats, Wistar ; S-Adenosylhomocysteine ; S-Adenosylmethionine ; Triglycerides

BACKGROUND/OBJECTIVE: The aim of this study was to examine the effect of high dietary methionine (Met) consumption on plasma and hepatic oxidative stress and dyslipidemia in chronic ethanol fed rats. MATERIALS/METHODS: Male Wistar rats were fed control or ethanol-containing liquid diets supplemented without (E group) or with DL-Met at 0.6% (EM1 group) or 0.8% (EM2 group) for five weeks. Plasma aminothiols, lipids, malondialdehyde (MDA), alanine aminotransferase (ALT), and aspartate aminotransferase were measured. Hepatic folate, S-adenosylmethionine (SAM), and S-adenosylhomocysteine (SAH) were measured. RESULTS: DL-Met supplementation was found to increase plasma levels of homocysteine (Hcy), triglyceride (TG), total cholesterol (TC), and MDA compared to rats fed ethanol alone and decrease plasma ALT. However, DL-Met supplementation did not significantly change plasma levels of HDL-cholesterol, cysteine, cysteinylglycine, and glutathione. In addition, DL-Met supplementation increased hepatic levels of folate, SAM, SAH, and SAM:SAH ratio. Our data showed that DL-Met supplementation can increase plasma oxidative stress and atherogenic effects by elevating plasma Hcy, TG, and TC in ethanol-fed rats. CONCLUSION: The present results demonstrate that Met supplementation increases plasma oxidative stress and atherogenic effects by inducing dyslipidemia and hyperhomocysteinemia in ethanol-fed rats.
Alanine Transaminase ; Animals ; Aspartate Aminotransferases ; Cholesterol ; Cysteine ; Diet ; Dyslipidemias* ; Ethanol ; Folic Acid ; Glutathione ; Homocysteine ; Humans ; Hyperhomocysteinemia ; Male ; Malondialdehyde ; Methionine* ; Oxidative Stress* ; Plasma ; Rats* ; Rats, Wistar ; S-Adenosylhomocysteine ; S-Adenosylmethionine ; Triglycerides