Biochemical consequences of 5-fluorouracil gastrointestinal toxicity in rats; effect of high-dose uridine

Selective protection of the normal host tissues from the toxic effects of anticancer agents would allow the use of higher, probably more effective, doses of the drugs. It has been demonstrated that delayed high-dose uridine administration after 5-fluorouracil decreases the extent of myelosuppression and causes faster regeneration of the bone marrow. We studied the biochemical consequences of the gastrointestinal toxicity caused by 5-fluorouracil and the potential of high-dose uridine treatment to influence these adverse effects. 5-Fluorouracil caused dose-related decreases in the biochemical parameters (thymidine kinase, sucrase, maltase, alkaline phosphatase) selected as early markers of the impaired metabolic activity of the intestinal mucosa. The nadir of the biochemical changes was reached between 24 h and 72 h after 5-fluorouracil treatment, and complete regeneration of the mucosa took 6–7 days. Delayed high-dose uridine administration failed to mitigate the severity of the gastrointestinal damage that ensued after 5-fluorouracil treatment, but caused significantly earlier regeneration of the mucosa.     

Rapid activation of glycogen synthase and protein phosphatase in human skeletal muscle after isometric contraction requires an intact circulation

The effects of isometric contraction (66% of maximal force) and recovery on glycogen synthase fractional activity (GSF) in human skeletal muscle have been studied. Biopsies were taken from the quadriceps femoris muscle at rest, at fatigue and 5 min postexercise on two occasions: after one of the contractions, the circulation to the thigh was occluded during the 5 min recovery (OCC), and after the other contraction, the circulation was intact (control, CON). During CON, GSF decreased from (mean ± SE) 0.34±0.05 at rest to 0.24±0.02 at fatigue and then increased to 0.74±0.04 at 5 min postexercise; corresponding values for OCC were 0.37±0.04, 0.25±0.04 and 0.48±0.05 (P<0.001 vs. CON for 5 min postexercise only). Compared with the value at fatigue, protein phosphatase activity (PP) increased by 79±16% during CON recovery (P<0.01), whereas no change was observed during OCC recovery. Uridine diphosphate glucose increased by approximately 2.5-fold at fatigue, remained elevated during OCC recovery, but reverted to the preexercise level during CON recovery (P<0.001 vs. OCC recovery). Glucose 6-P increased approximately 5-fold at fatigue and was higher at 5 min postexercise in OCC vs. CON recovery (8.6±1.5 vs. 4.1±0.9 mmol/kg dry wt; P<0.01). It is concluded that the rapid increase in GSF after intense exercise with an intact circulation may be at least partly attributed to an increase in the specific activity of PP. The increase in GSF during recovery in OCC may be at least partly attributed to the high glucose 6-P content in vivo, which enhances the substrate suitability of GS for PP. Thus, separate mechanisms exist for the activation of PP and GS during recovery from intense short term exercise.     

Salvage of pyrimidine nucleosides by Trichomonas vaginalis

Trichomonas vaginalis is incapable of de novo pyrimidine biosynthesis because it cannot incorporate bicarbonate, aspartate or orotate into its pyrimidine nucleotides or nucleic acids. The organism can salvage exogenous cytidine greater than uridine greater than uracil and thymidine, and incorporate them into the nucleotide pool. A portion of cytidine is converted to CMP, CDP and CTP by cytidine phosphotransferase and nucleotide kinases. Some cytidine and most of uracil are, however, converted first to uridine by cytidine deaminase and uridine phosphorylase respectively; uridine is then incorporated into UMP, UDP and UTP by uridine phosphotransferase and nucleotide kinases. The two phosphotransferases, found mainly in the non-sedimentable fraction of T. vaginalis, provide the main avenue of pyrimidine salvage. No significant levels of pyrimidine phosphoribosyl transferase or nucleoside kinases can be detected in the extract. T. vaginalis has no appreciable dihydrofolate reductase or thymidylate synthetase; it grows normally in millimolar concentrations of methotrexate, pyrimethamine, or trimethoprim, and cannot incorporate labels from exogenous uracil or uridine into DNA. It has an enzyme thymidine phosphotransferase in the sedimentable fraction which converts thymidine to TMP. Thymidine salvage in T. vaginalis is thus totally isolated from the rest of the pyrimidine salvage.     

Evidence for two separate vasoconstriction-mediating nucleotide receptors,both distinct from the P2X-receptor,in rabbit basilar artery: a receptor for pyrimidine nucleotides and a receptor for purine nucleotides

Summary Uridine 5-triphosphate- (UTP-) and adenosine 5-triphosphate-(ATP) induced vasoconstriction was studied in the rabbit basilar artery. The arteries were incubated and perfused at a constant rate of flow. Vasoconstriction was measured as an increase in perfusion pressure.Serotonin, histamine and noradrenaline caused concentration-dependent vasoconstriction, with potency decreasing in that order. Of the nucleotides tested, UTP, UDP, UMP, CTP, ATP, ADP, adenosine 5-O-(3-thio)triphosphate (ATPS), and ,-imido adenosine 5-triphosphate (AMP-PNP) elicited concentration-dependent vasoconstriction, whereas AMP, 2-methylthio-ATP, , -methylene-ATP and ,-methylene-ATP up to 10^–3 mol/l caused no or only a very small increase in perfusion pressure. The order of potency of the pyrimidine nucleotides was: UTP = UDP UMP = CTP; that of the purine nucleotides was: ATPS > AMP-PNP > ATP > ADP > 2-methylthio-ATP = , -methylene-ATP = ,-methylene-ATP. The vasoconstrictor effects of UTP and ATP were not or only to a minor degree influenced by: phentolamine; a mixture of atropine, diphenhydramine and methysergide; indometacin; nordihydroguaiaretic acid; denervation by 6-hydroxydopamine; or mechanical removal of endothelium. Prolonged exposure to ,-methylene-ATP elicited only a very small vasoconstriction and did not change the constrictor effects of UTP or ATP. Prolonged exposure to ATPS elicited marked vasoconstriction; subsequently, responses to ATP were reduced whereas those to UTP were, if anything, slightly enhanced. Reactive blue 2 reduced neither the UTP- nor the ATP-induced vasoconstriction. ATP 10^–3 mol/l elicited marked additional vasoconstriction after precontraction with UTP 10^–3 mol/l, whereas UTP elicited only a very small additional vasoconstriction when its concentration was doubled from 10^–3 to 2 × 10^–3 mol/l.It is concluded that, in the rabbit basilar artery, the vasoconstrictor response to UTP is mediated by a pyrimidine nucleotide receptor which is distinct from the P₂-purinoceptor, and that the vasoconstrictor response to ATP is mediated by a P₂-receptor which is distinct from the known P₂-subtypes.Send offprint requests to I. v. Kügelgen at the above address     

不同药物抗风疹病毒的实验研究

目的为筛选有效的抗RV药物。方法选用9种新合成的腺嘌呤衍生物、6种尿嘧啶衍生物及大黄醇提液,分别在BHK21、RNC和HNC细胞上进行了体外抗病毒试验。在BHK21上以CPE为观察指标,在RNC和HNC上因不出现明显的CPE,则将细胞培养物转种于BHK2l细胞并用间接免疫荧光和免疫酶技术检测药物的抗病毒效应。结果取代基为—CH2—C6H5、—(CH2)2OH、—C6H5—CH3的腺嘌呤衍生物及取代基为—CH3、—(CH2)2OH、—C6H5—CH3、—C6H5—Cl的尿嘧啶衍生物,对RVJR-23的最小抑毒剂量在78～625mg／L之间;大黄醇提液对RVJR-23的最小抑毒剂量为5000mg／L。结论上述药物均有抗RV作用,大黄醇提液的作用较新合成的部分腺嘌呤与尿嘧啶衍生物更为明显,且毒性小。     

The successful treatment of 5-fluorouracil (5-FU) overdose in a patient with malignancy and HIV/AIDS with uridine triacetate

According to the NIH, about 275 000 patients receive treatment with 5-Fluorouracil (5-FU) and more than 1300 die from 5-FU toxicity every year from life-threatening myelosuppression, gastrointestinal complications, and neurotoxicity. Immunocompromised persons are at higher risk of developing toxicity. Recently uridine triacetate (Vistagard®) has been approved by the Food and Drug Administration (FDA) as the only specific antidote available for 5-FU poisoning. In a clinical trial (n = 135), 96% of patients with 5-FU toxicity recovered after treatment, where as in a historical control group only 10% survived. This is the first published case report of survival after 5-FU overdose who also was immunocompromised from HIV/AIDs. A 52 year old male with history of HIV/AIDS (CD4 70), CNS toxoplasmosis and anal cancer presented to the emergency department after realizing he had received an entire course of 5-FU in 24 instead of 96 h. Treatment with uridine triacetate was arranged in the emergency department. After receiving treatment the patient was asymptomatic and had an uncomplicated hospital course. 5-FU poisoning must be recognized early as uridine triacetate is approved by the FDA for use within 96 h following the end of 5-FU administration. Emergency medicine physicians should promptly recognize and treat 5-FU poisoning. However, this may be challenging as patients may not seek medical attention until many hours or several days after last administration since symptoms are often delayed with 5-FU poisoning.     

Human liver stem/progenitor cells decrease serum bilirubin in hyperbilirubinemic Gunn rat

AIM:To test the ability of adult-derived human liver stem/progenitor cells(ADHLSC)from large scale cultures to conjugate bilirubin in vitro and in bilirubin conjugation deficient rat.METHODS:ADHLSC from large scale cultures were tested for their phenotype and for their capacity to conjugate bilirubin in vitro after hepatogenic differentiation.In vivo,Gunn rats[uridine diphosphate-glucuronosyltransferase 1A1(UGT1A1)deficient animal]were injected with ADHLSC and cryopreserved hepatocytes(positive control).Two,4,13 and 27 wk posttransplantation,transplanted Gunn rat bilirubin serum levels were determined by high performance liquid chromatography.Human cell engraftment of trans-planted cells was assessed 27 wk post-transplantation using immunohistochemistry and RTqPCR.RESULTS:Large scale culture conditions do not modified ADHLSC phenotype,ADHLSC were able to specifically conjugate bilirubin.ADHLSC were intraportally injected into Gunn rats and blood UCB was measured at different times post-transplantation,infused-Gunn rats exhibited a metabolic effect 3 mo post-transplantation and maintained over a 6 mo period.ADHLSC engraftment into Gunn rat’s liver was demonstrated by RTqPCR and immunohistochemistry against albumin and UGT1A1.CONCLUSION:ADHLSC from large scale cultures are efficient in conjugating bilirubin in vitro and in restoring a deficient metabolic function(reducing bilirubin level)in hyperbilirubinemic rats.     

UGT1A1基因复合杂合突变致吉尔伯特综合征一例

一例吉尔伯特综合征患儿自幼反复出现巩膜黄染,无其他自觉症状;血清胆红素水平升高,以非结合胆红素为主;排除胆道梗阻、溶血等其他引起黄疸的因素;基因检测发现患儿尿苷二磷酸葡糖苷酸转移酶1A1（UGT1A1）基因存在UGT1A1*28和c.211G>A杂合突变。     

UPLC法同时测定盐酸阿糖胞苷原料药的含量和有关物质

目的:建立同时测定盐酸阿糖胞苷原料药的含量和有关物质的方法。方法:采用超高效液相色谱法。色谱柱为Inertsil ODS-3 C18,流动相为磷酸盐缓冲液-甲醇(梯度洗脱),流速为0.8 ml/min,检测波长为254 nm,柱温为40Ⅴ,进样量为10μl。结果:尿嘧啶、尿苷、阿糖尿苷、盐酸阿糖胞苷检测质量浓度分别在0.100 8²0.16、0.120.16、0.1²0.12、0.095 620.12、0.095 6¹9.12、0.119.12、0.1²0.004μg/ml范围内与各自峰面积积分值呈良好的线性关系(r=0.999 9、0.999 8、0.999 9、0.999 9);精密度、稳定性、重复性试验的RSD≤0.79%;尿嘧啶、尿苷、阿糖尿苷平均加样回收率为103.8%、102.2%、99.7%,RSD分别为2.44%、2.69%、3.16%(n=9)。结论:该方法准确、灵敏度高、专属性强、重复性好,可用于盐酸阿糖胞苷原料药的质量控制。     

尿N-乙酰-β-D氨基葡萄糖苷酶在IgA肾病肾小管间质损伤中的评估价值

目的评估尿N-乙酰-β-D氨基葡萄糖苷酶在IgA肾病肾小管间质损伤中的价值。方法回顾性分析2014年2月至2018年6月于本院行肾穿刺活检确诊为IgA肾病的患者82例,分为NAG正常组(NAG<12 U/L,14例)、NAG升高组(NAG>12 U/L,68例);分析两组患者间临床与病理指标的差异,并评估NAG与肾小管间质病变的相关关系。结果NAG正常组的NAG、血肌酐、胱抑素-C、尿微量白蛋白的统计量显著低于NAG升高组(P<0.05),NAG正常组的eGFR的统计量显著高于NAG升高组(P<0.05),病理改变中,NAG正常组的肾小球系膜细胞增殖、肾间质炎症细胞浸润、肾间质纤维化、肾小管萎缩积分显著低于NAG升高组,进一步logistic回归分析显示微量白蛋白、eGFR、系膜增殖、肾小管间质的病理改变为影响NAG水平的独立危险因素。结论尿NAG水平与患者eGFR、mALB以及小管间质病变密切相关,可以作为评估和监测IgAN的小管间质病变程度的临床指标。