INFLUENCE OF DIURESIS ON ENZYMURIA

Urinary excretion of renal brush border enzymes may serve as an early marker of renal injury. However, the distinction between physiological and pathological levels remains controversial, since enzymuria is affected by physiological parameters. To clarify the influence of diuresis, we investigated the urinary excretion of alanine-aminopeptidase (AAP; EC 3.4.11.2) as function of diuretic state. 17 healthy volunteers of both sexes were subjected to protocols with sudden or prolonged water load preceded and followed by a thirst period. Urinary excretion of AAP was measured using an enzyme kinetic assay. As expected AAP excretion increased with urine flow, the increments diminished yielding an overall excretion pattern that resembled saturation kinetics. This function is described by a mathematical model. This model assumes, that AAP is released in proximal tubules at a constant rate and reabsorbed or inactivated in the distal tubule and collecting duct. Non-linear fits of the model equation to our data allowed two parameters, χ and μ, to be defined. χ describes the rate of AAP release independent of urinary flow, and μ the ratio of distal tubular reabsorption or inactivation. If a substrate is not reabsorbed at all, μ approximates zero. Since μ fitted for AAP differed significantly from zero, this indicates reabsorption or inactivation of AAP in the distal nephron. Therefore, our study supports the theory of flow-dependent reabsorption or inactivation of AAP in the distal nephron.     

MK2 plays an important role for the increased vascular permeability that follows thermal injury

We previously reported Rho kinase is involved in vessel hyper-permeability caused by burns. Here we further explore the Rho kinase downstream signaling, it is found that its specific inhibitor Y27632 significantly diminishes the activation of JNK and p38 MAPKs but not ERK that induced by serum from burned rats (burn-serum). JNK activation was found involved in the expression of HUVEC adhesion molecules following thermal injury, although not in the process of stress fiber formation. Inhibition of various MAPKs by specific inhibitors showed that SB203580 (inhibitor of p38), but neither SP600125 (inhibitor of JNK) nor PD98059 (inhibitor of ERK), abolish activation of the p38 downstream kinase MK2. Demonstration of stress fibers by fluorescent-labeled phalloidin showed that inhibition of MK2, either by its specific inhibitor or by dominant negative adeno-viral-carried constructs, significantly reduced burn-serum-induced HUVEC stress-fiber formation, while inhibition of another downstream p38 MAPK kinase, PRAK, had no such effects. Transfection of dominant negative adeno-viral MK2 (Ad-MK2(A)) significantly inhibited thermal injury-induced blood vessel hyper-permeability in rats and, moreover, prolonged the survival of burned rats beyond 72 h following thermal injury. One of the mechanisms behind these phenomena is that Ad-MK2(A) causes a significant depression of burn-serum-induced HSP27-phosphorylation, while the adeno-viral transported dominant negative PRAK (Ad-PRAK(A)) does not block. Although the effect of blockade of MK2 through its adeno-viral approach requires further study and investigation of alternatives to know for sure, we may have found a new pathway behind thermal-injury-induced blood vessel hyper-permeability, namely: Rho kinase > p38 > MK2 > HSP27.     

A Conformationally Gated Model of Methadone and Loperamide Transport by P-Glycoprotein

P-glycoprotein (Pgp) is a multidrug resistance transporter that limits the penetration of a wide range of neurotherapeutics into the brain including opioids. The diphenylpropylamine opioids methadone and loperamide are structurally similar, but loperamide has about a 4-fold higher Pgp-mediated transport rate. In addition to these differences, they showed significant differences in their effects on Pgp-mediated adenosine triphosphate (ATP) hydrolysis. The activation of Pgp-mediated ATP hydrolysis by methadone was monophasic, whereas loperamide activation of ATP hydrolysis was biphasic implying methadone has a single binding site and loperamide has 2 binding sites on Pgp. Quenching of tryptophan fluorescence with these drugs and digoxin showed competition between the opioids and that loperamide does not compete for the digoxin-binding site. Acrylamide quenching of tryptophan fluorescence to probe Pgp conformational changes revealed that methadone- and loperamide-induced conformational changes were distinct. These results were used to develop a model for Pgp-mediated transport of methadone and loperamide where opioid binding and conformational changes are used to explain the differences in the opioid transport rates between methadone and loperamide.     

The Influence of In Vivo Metabolic Modifications on ADMET Properties of Green Tea Catechins–In Silico Analysis

The health effects of green tea are associated with catechins: (?)-epigallocatechin-3-O-gallate (EGCG), (?)-epigallocatechin, (?)-epicatechin-3-O-gallate, and (?)-epicatechin. An understanding of compound absorption, distribution, metabolism, excretion, and toxicity characteristics is essential for explaining its biological activities. Herein, absorption, distribution, metabolism, excretion, and toxicity properties of in vivo detected metabolites of green tea catechins (GTCs) have been analyzed in silico. The influence of metabolic transformations on absorption, distribution, metabolism, and excretion profiles of GTCs corresponds to the effects of size, charge, and lipophilicity, as already observed for other small molecules. Mutagenic, carcinogenic, or liver toxic effects were predicted only for a few metabolites. Similar to galloylated GTCs EGCG and (--)-epicatechin-3-O-gallate, the sulfo-conjugates were predicted to bind at the warfarin binding site. The low free plasma concentration of these derivatives may be consequential to their serum albumin binding. The activity cliff detected for methylated conjugates of EGCG indicates that GTCs' pro-oxidative activity in bound state comes primarily from free hydroxyl groups of the pyrogallol ring B.     

Protein kinase C isoforms in atherosclerosis: Pro- or anti-inflammatory?

Atherosclerosis is a pathologic condition caused by chronic inflammation in response to lipid deposition in the arterial wall. There are many known contributing factors such as long-term abnormal glucose levels, smoking, hypertension, and hyperlipidemia. Under the influence of such factors, immune and non-immune effectors cells are activated and participate during the progression of atherosclerosis. Protein kinase C (PKC) family isoforms are key players in the signal transduction pathways of cellular activation and have been associated with several aspects of the atherosclerotic vascular disease. This review article summarizes the current knowledge of PKC isoforms functions during atherogenesis, and addresses differential roles and disputable observations of PKC isoforms. Among PKC isoforms, both PKCβ and PKCδ are the most attractive and potential therapeutic targets. This commentary discusses in detail the outcomes and current status of clinical trials on PKCβ and PKCδ inhibitors in atherosclerosis-associated disorders like diabetes and myocardial infarction. The risk and benefit of these inhibitors for clinical purposes will be also discussed. This review summarizes what is already being done and what else needs to be done in further targeting PKC isoforms, especially PKCβ and PKCδ, for therapy of atherosclerosis and atherosclerosis-associated vasculopathies in the future.     

巨噬细胞移动抑制因子的表达与食管癌的临床病理指标的相关性

目的探讨巨噬细胞移动抑制因子（macrophage migration inhibitory factor,MIF）在食管癌组织中的表达与食管癌的临床病理指标的相关性,及其在肿瘤发生中的可能作用。方法收集2010年1月—2012年9月间新疆医科大学第一附属医院经手术切除并存档的食管癌组织标本40例,癌旁组织标本20例。应用s—P免疫组化方法检测食管癌组织及癌旁食管上皮组织中MIF的表达情况。结果组织中MIF阳性表达在食管癌组明显高于癌旁组织组,差异有统计学意义（P〈0．05）;MIF的表达和肿瘤部位、肿瘤直径、病理类型、分化程度等均无明显相关（P〉0．05）,与食管癌患者的肿瘤浸润范围、淋巴结转移、远处转移、TNM分期有关（P〈0．05）。结论MIF在食管癌组织中高表达,与肿瘤的浸润范围、淋巴结转移、远处转移及TNM分期相关,MIF可以作为一种诊断食管黏膜癌变的免疫组织化学检测指标。     

核桃青皮提取物对食管癌细胞增殖的抑制作用及其分子机制的探讨

目的观察核桃青皮提取物对人食管癌细胞增殖的抑制作用.方法：用MTT法分别测定核桃青皮粗提物和核桃青皮提取物没食子酸、乙酸乙酯、紫杉叶素、7-D-芹菜糖-儿茶酚对食管癌细胞EC9706和KYSE150的增殖抑制率,并用Western Blot检测不同药物处理后食管癌细胞中细胞周期相关蛋白CyclinD1的蛋白表达.结果：核桃青皮粗提物、没食子酸和乙酸乙酯能抑制食管癌细胞的增殖,其作用呈明显剂量依赖性,当药物浓度增加至80 μg/mL时,对KYSE150的抑制率分别为82.75% 、90.51%、88.36%,对EC9706的抑制率分别为85.54% 、87.21%、85.17%.与对照组相比,3种药物均会显著抑制KYSE150和EC9706细胞中CyclinD1的表达.结论：核桃青皮提取物对食管癌细胞系的增殖有较强的抑制作用,其机制可能与引起细胞周期阻滞有关.