Role of cytochrome P450 2B1 in puromycin aminonucleoside-induced cytotoxicity to glomerular epithelial cells

Puromycin aminonucleoside (PAN)-induced glomerular injury in rats mimics minimal-change nephrotic syndrome (NS) in humans. We have demonstrated an important role of cytochrome P450 (CYP) as a significant source of catalytic iron in this model of NS. The current study was designed to identify CYP isozyme(s) present in the rat glomerular epithelial cells (GEC) and to explore the role of the specific CYP isozyme in PAN-induced cytotoxicity. CYP2B1 was identified in GEC by immunocytochemistry and Western blot. Treatment of GEC with PAN resulted in a marked generation of hydrogen peroxide (H(2)O(2)) and reduction of CYP2B1 content associated with significant increase in catalytic iron and hydroxyl radical formation. Preincubating GEC with CYP2B1 inhibitors (piperine and cimetidine) and H(2)O(2) scavenger (pyruvate) significantly reduced H(2)O(2 )generation, preserved CYP2B1 content, prevented the increase in catalytic iron and hydroxyl radical formation including PAN-induced cytotoxicity. We also observed the induction of heme oxygenase (HO-1) in PAN-treated GEC, and this up-regulation was reduced by pretreatment of the CYP inhibitors and pyruvate. Our data thus indicate an important role of CYP2B1 in PAN-induced cytotoxicity by serving as a site of reactive oxygen metabolite generation and a significant source of catalytic iron.     

Anti-human immunodeficiency virus effects of dextran sulfate are strain dependent and synergistic or antagonistic when dextran sulfate is given in combination with dideoxynucleosides.

The effects of three molecular weight ranges of dextran sulfate on five different human immunodeficiency virus (HIV) isolates (from patients with acquired immunodeficiency syndrome), alone and in combination with dideoxynucleosides, were investigated in vitro. The higher the molecular weight range of dextran sulfate, the more potent the activity as assessed by a quantitative syncytium formation assay. Although all five HIV isolates had similar susceptibilities to the inhibitory effects of dideoxynucleosides, the two clinical isolates of HIV (HIV type 1 [HIV-1] TM and SP) exhibited a pattern of reduced susceptibility to dextran sulfate when compared with the two cloned isolates (HIV-1 WMF and HIV-2 ROD) and a prototype laboratory strain (HIV-1 IIIB). In combination with dideoxynucleosides, the high-molecular-weight range of dextran sulfate (500,000) resulted in an antagonistic response directed against the two clinical isolates of HIV (HIV-1 TM and SP) when the antiviral concentrations of dextran sulfate were in the ineffective range. Additive or synergistic effects were seen with the other three HIV isolates and all five HIV isolates when the low-molecular-weight range of dextran sulfate (8,000) was used. The results of these studies raise issues on the impact of drug-resistant strains on disease progression and the use of dextran sulfate in combination with nucleoside analogs for the clinical management of HIV disease.     

婴儿骨化性肾肿瘤的临床病理观察

目的探讨婴儿骨化性肾肿瘤的临床病理特点、组织起源及其诊断和鉴别诊断。方法对1例婴儿骨化性肾肿瘤的临床、影像学和病理特征进行观察并复习文献。结果患儿因肉眼血尿入院,影像学检查提示左肾下极钙化性肿物和左下肾盏、肾盂变形。大体见肿物包膜完整,灰白、灰黄色,略呈结节状,剖面质硬,灰白色,局部呈囊性,可见出血;镜下肿瘤由骨样基质、成骨样细胞和梭形细胞组成;免疫组化染色示部分成骨样细胞vimentin、EMA和CK（＋）,梭形细胞vimentin（＋）,Ki-67〉5%（＋）,且阳性细胞主要是梭形细胞。结论婴儿骨化性肾肿瘤具有独特的临床表现、影像学改变及病理特征,是一种少见的良性肾肿瘤,预后良好。     

Augmented renal clearance: a retrospective,cohort study of urinary creatinine clearance in critically ill patients in the United Kingdom

ObjectiveAugmented renal clearance (ARC) is associated with sub-therapeutic antibiotic, anti-epileptic, and anticoagulant serum concentrations leading to adverse patient outcomes. We aimed to describe the prevalence and associated risk factors for ARC development in a large, single-centre cohort in the United Kingdom.MethodsWe conducted a retrospective observational study of critically unwell patients admitted to intensive care between 2014 and 2016. Urinary creatinine clearance was used to determine the ARC prevalence during the first 7 days of admission. Repeated measures logistic regression was used to determine risk factors for ARC development.ResultsThe ARC prevalence was 47.0% (95% confidence interval [95%CI]: 44.3%–49.7%). Age, sex, Acute Physiology and Chronic Health Evaluation (APACHE) II score, and sepsis diagnosis were significantly associated with ARC. ARC was more prevalent in younger vs. older (odds ratio [OR] 0.95 [95%CI: 0.94–0.96]), male vs. female (OR 0.32 [95%CI: 0.26–0.40]) patients with lower vs. higher APACHE II scores (OR 0.94 [95%CI: 0.92–0.96]).ConclusionsThis patient group probably remains unknown to many clinicians because measuring urinary creatinine clearance is not usually indicated in this group. Clinicians should be aware of the ARC risk in this group and consider measurement of urinary creatinine clearance.     

Sustained reductions in oxipurinol renal clearance during a restricted diet

The renal clearance of oxipurinol, the major metabolite of allopurinol, was studied in six healthy subjects during normal and restricted (low protein and low calorie) diets. A 600 mg oral dose of allopurinol was administered after 7 days of a normal diet (100 mg protein/day) and again after 2 and 4 weeks of a restricted diet (19 gm protein/day). The renal clearance of oxipurinol was reduced from 19.6 +/- 1.5 ml/min during the normal diet to 10.9 +/- 0.8 and 12.0 +/- 0.9 ml/min (both P less than 0.001) during the restricted diet at 2 and 4 weeks, respectively. These changes in oxipurinol renal clearance paralleled changes in uric acid renal clearance. Furthermore, the plasma oxipurinol half-life was increased from 27.0 +/- 1.7 hours during the normal diet to 51.1 +/- 4.3 and 45.7 +/- 3.7 hours (both P less than 0.001) during the restricted diet at 2 and 4 weeks, respectively. We conclude that dietary protein and calorie restriction cause a sustained reduction in the elimination of oxipurinol.     

Hemofiltration clearance of flecainide in a patient with acute renal failure

Flecainide, a new antiarrhythmic drug, has been shown not no be removed to a significant extent by hemodialysis or peritoneal dialysis, in spite of a high renal clerance. Its systemic and hemofiltrate clearances, measured in a patient under continuous hemofiltration, were 402 and 19.7 ml/min respectively. The clearance ratio of less than 5% makes the contribution of hemofiltration to the elimination of flecainide clinically negligeable.     

Reduction of low-density lipoproteins with dextran sulfate in patients with familial hypercholesterolemia

A novel on-line system for the selective precipitation of low-density lipoprotein (LDL) using dextran sulfate has been devised and tested in four patients with heterozygous familial hypercholesterolemia (type II). The mean pretreatment serum cholesterol was 410 mg/dl. Plasma was generated by membrane filtration and LDL and VLDL (very-low-density lipoprotein) were completely precipitated with 10-35 mg% dextran sulfate (Mr 5,000) in the presence of 55 mM Ca2+. The precipitate was removed by filtration and the excess Ca2+ by dialysis. For 41 procedures the mean reduction of plasma solutes was LDL + VLDL 65%, HDL 23%, fibrinogen 19%, albumin 15%, IgG 20%, IgA 19%, IgM 24%. We conclude that dextran sulfate precipitation is an effective method for selective on-line removal of LDL from plasma.     

硫酸镁治疗急性脑卒中的临床观察

目的 评价硫酸镁注射液治疗急性脑卒中的临床疗效及安全性。方法 随机分成治疗组和对照组。两组均采用胞二磷胆碱静脉滴注作为基础治疗。治疗组加用硫酸镁注射液静脉滴注,共用15天为1个疗程。结果 治疗组疗效明显优于对照组,不良反应轻微。结论 硫酸镁注射治疗急性脑卒中疗效肯定,安全。     

Renal clearance of gamma-hydroxybutyric acid in rats: increasing renal elimination as a detoxification strategy

Intoxication with gamma-hydroxybutyric acid (GHB) is associated with coma, seizure, and death; treatment of overdoses is symptomatic. The objectives of this investigation were to characterize the renal clearance and total clearance of GHB in rats and to evaluate potential strategies for increasing the elimination of GHB after drug overdoses. GHB was administered by i.v. infusion at low (108 mg/h/kg), medium (128 mg/h/kg), or high (208 mg/h/kg) doses. Crossover studies were performed under steady-state conditions using the medium dose in the absence or presence of l-lactate, pyruvate, d-mannitol, sodium bicarbonate, or normal saline. GHB in plasma and urine samples was assayed using liquid chromatography-tandem mass spectrometry. Infusion of the low, medium, and high doses of GHB produced steady-state plasma concentrations of 0.22 +/- 0.04, 0.43 +/- 0.05, and 0.68 +/- 0.11 mg/ml. The renal clearance of the medium (51.8 +/- 13.0 ml/h/kg) and high (97.1 +/- 43.1 ml/h/kg) doses was significantly higher than that of the low dose (14.9 +/- 5.1 ml/h/kg), whereas the total clearance values were significantly lower than that of the low dose. The renal clearance was significantly increased by the concomitant administration of l-lactate, pyruvate, d-mannitol, or sodium bicarbonate with GHB but was not altered by normal saline. The total and metabolic clearance values were significantly increased by all treatments except normal saline. Overall, our results indicated that the renal clearance of GHB is dose-dependent, involving capacity-limited reabsorption. Monocarboxylate transport inhibitors, osmotic diuresis using d-mannitol, or the administration of sodium bicarbonate can increase the renal and total clearances of GHB. The approaches used in this investigation may offer potential detoxification strategies for the treatment of GHB overdoses.     

Cholesterol in high-density lipoprotein: use of Mg2+/dextran sulfate in its enzymic measurement.

We describe a method for measuring high-density lipoprotein cholesterol. MgCl2 and dextran sulfate are used to precipitate all low-density and very-low-density lipoproteins. The supernate contains only high-density lipoproteins, the cholesterol concentration of which is estimated by an enzymic method, with a discrete analyzer (Abbott Bichromatic Analyzer). Concentration and instrument response are linearly related to 50 mg/liter. The precision of the method is excellent in the range of clinical interest (100 to 1000 mg of cholesterol per liter). The precision and efficiency of the precipitation are shown at various concentrations of high-density lipoprotein cholesterol. The method was compared to that of two laboratories in the Cooperative Lipoprotein Phenotyping Study group by testing a number of split samples, and agreement was good.     

Efficacy of keratinocyte growth factor-2 in dextran sulfate sodium-induced murine colitis.

The purpose of this study was to determine the efficacy of a novel human protein, keratinocyte growth factor-2 (KGF-2), in a model of murine colitis induced by ad libitum exposure to a 4% solution of dextran sulfate sodium (DSS) in the drinking water. Initial evaluation of KGF-2 was based on its ability to reduce weight loss, stool score, and histological score in mice exposed to DSS for 7 days. When KGF-2 (0.1-10.0 mg/kg i.p. or s.c.) was injected daily into DSS-treated mice from day 0 to 7, it significantly reduced all three parameters in a dose-response fashion, with a minimum effective dose of between 1 and 3 mg/kg. When KGF-2 was given therapeutically, starting 4 days after initiation of the 7-day DSS treatment, the 3- but not the 0.5-mg/kg dose significantly enhanced weight recovery after discontinuation of DSS treatment. When DSS treatment was prolonged beyond the normal 7 days, therapeutic intervention on day 2 or 4 also significantly reduced mortality, weight loss, and stool score at the 1- and 3-mg/kg dose. Therapeutic treatment also resulted in reduction of colon myloperoxidase levels by more than 50%. These experiments suggest that KGF-2 may be clinically useful in the treatment of inflammatory bowel diseases such as ulcerative colitis and Crohn's disease.     

Stereoselective renal clearance of pindolol in humans.

In this study, pindolol, a beta-adrenoceptor blocking agent marketed as a racemic mixture, was used as a model compound to investigate stereoselective renal clearance of organic cations in human beings. Six normal subjects received an oral dose of 20 mg racemic pindolol. Heart rate and blood pressure were measured throughout the study. A stereospecific high performance liquid chromatographic procedure was used to quantitate the concentrations of d- and l-pindolol in plasma and urine. Renal clearance and other pharmacokinetic parameters of both enantiomers were calculated and compared. The renal clearance of l-pindolol was greater than that of d-pindolol in all subjects. The renal clearance (mean +/- SD) was 240 +/- 55 ml/min for l-pindolol and 200 +/- 51 ml/min for d-pindolol (P less than 0.01). Since stereoselective binding to plasma proteins was not observed, differences in renal clearance between d- and l-pindolol were caused by either stereoselective renal transport, or stereoselective renal metabolism. The area under the plasma concentration-time curve, the amount of drug excreted, and the half-life of l-pindolol were greater than those of d-pindolol, which suggests that pindolol was also eliminated stereoselectively by nonrenal routes. The slopes of the resting heart rate vs. the plasma concentration of l-pindolol were significantly less than zero and were significantly correlated to the pretreatment heart rate, which supports the hypothesis that intrinsic sympathetic tone largely determines the effect of pindolol on the resting heart rate. The observation that pindolol is eliminated stereoselectively by the kidney may have clinical implications for other racemic drugs that are renally eliminated.     

新型硫酸葡聚糖血脂分离系统治疗高脂血症

目的 采用新型硫酸葡聚糖(DS)血脂分离系统用于治疗高脂血症,在保证安全、有效的基础上简化血脂分离工艺,大幅度降低治疗费用.方法 选择南京医科大学第一附属医院肾内科50例患者共110例次血脂分离治疗,首先用单采机采集患者高脂血浆,按10ml/kg体重采集总量(600 ± 100)ml.然后血浆中加入静脉注射用DS作为吸附剂,Ca2 作为催化剂,DS特异性吸附LDL形成大颗粒,用离心法去除胆固醇、三酰甘油.结果 每次血脂分离治疗总胆固醇下降11%(6.52±0.5)和(5.8±0.4);三酰甘油下降15%(3.85±2.1)和(3.27±1.5);LDL-C下降20%(4.03±0.86)和(3.2±0.52);HDL-C保持不变(1.13±0.28)和(1.13±0.41);白蛋白保持不变(45±5)和(45±4),过量的Ca2 被阳离子树脂柱完全吸附.结论 新型DS血脂分离系统工艺合理、操作过程简单、易于推广应用.特别是治疗费用低廉,更适合需要多次治疗才能纠正血脂异常的患者.