Alpha-naphthylisothiocyanate modulates hepatobiliary transporters in sandwich-cultured rat hepatocytes

Alpha-naphthylisothiocyanate (ANIT) induces intra-hepatic cholestasis mixed with hepatocellular injury mainly by bile ductular damage. However, its direct effect on hepatic parenchymal cells (hepatocytes) is unclear. Sandwich-cultured rat hepatocytes (SCRH) were applied to clarify this question. Though cytotoxicity was not observed (0–180 μM) in ANIT-treated SCRH, metabonomics analysis of the hepatocytes revealed a shift in the metabolic pattern and a decrease in cellular cholesterol level, accompanied by an increase in total bile acids after 48 h ANIT (5–45 μM) treatment. To assess the function of major hepatic bile acid transporters, the accumulation and efflux of [D-Pen^2,5]-enkephalin (DPDPE), 5 (and 6)-carboxy-2′,7′-dichlorofluorescein (CDF) diacetate promoiety and deuterium-labeled sodium taurocholate (d8-TCA) were measured. ANIT incubation for either 30 min or 48 h led to dose-dependent decreases in the biliary excretion index (BEI) of DPDPE and CDF, as well as the intracellular accumulation of d8-TCA, CDF and DPDPE. The basolateral efflux of d8-TCA was also decreased with its BEI barely changed. mRNA expression of multiple uptake transporters and bile acid synthesizing enzymes was down-regulated after 48 h incubation. In conclusion, ANIT could directly induce retention of bile acids in hepatocytes by inhibiting the function of bile acid transporters, which might contribute to its cholestatic effect.     

How main-chains of proteins explore the free-energy landscape in native states

Understanding how a single native protein diffuses on its free-energy landscape is essential to understand protein kinetics and function. The dynamics of a protein is complex, with multiple relaxation times reflecting a hierarchical free-energy landscape. Using all-atom molecular dynamics simulations of an α/β protein (crambin) and a β-sheet polypeptide (BS2) in their “native” states, we demonstrate that the mean-square displacement of dihedral angles, defined by 4 successive C^α atoms, increases as a power law of time, t^α, with an exponent α between 0.08 and 0.39 (α = 1 corresponds to Brownian diffusion), at 300 K. Residues with low exponents are located mainly in well-defined secondary elements and adopt 1 conformational substate. Residues with high exponents are found in loops/turns and chain ends and exist in multiple conformational substates, i.e., they move on multiple-minima free-energy profiles.     

单纯性肥胖者和糖尿病患者血清胰多肽水平观察

本文用自制胰多肽(PP)放射免疫分析试剂盒,观察了24例单纯性肥胖者和34例糖尿病患者空腹和餐后PP的分泌水平,结果与18例正常人比较,发现肥胖者PP、胰岛素、C肽和血糖均呈高分泌现象;糖尿病病人PP水平也增高,但C肽和胰岛素则降低。     

The glucose dependent insulinotropic polypeptide response to oral glucose and mixed meals is increased in patients with Type 2 (non-insulin-dependent) diabetes mellitus

Summary Considerable disagreement exists regarding the levels of immunoreactive glucose dependent insulinotropic polypeptide in patients with Type 2 (non-insulin-dependent) diabetes mellitus. Glucose dependent insulinotropic polypeptide levels were therefore studied during oral glucose and mixed meal tolerance tests in normal subjects (n=31) and newly presenting previously untreated patients with Type 2 diabetes mellitus (n=68). The tests were performed in random order after overnight fasts and blood samples were taken at 30 min intervals for 4 h. During the oral glucose tolerance test plasma glucose dependent insulinotropic polypeptide levels increased in the normal subjects from a fasting value of 20±3 pmol/l to a peak of 68±5 pmol/l at 30 min and in the Type 2 diabetic patients from a similar fasting level of 27±3 pmol/l to a higher peak value of 104±6 pmol/l at 30 min (p<0.001). Glucose dependent insulinotropic polypeptide levels were significantly higher in the diabetic patients compared with the normal subjects from 30–90 min (p<0.01–0.001) following oral glucose. During the meal tolerance test glucose dependent insulinotropic polypeptide levels increased in the normal subjects from a pre-prandial value of 22±4 pmol/l to a peak of 93±6 pmol/l at 90 min and in the Type 2 diabetic patients from a similar basal level of 25±2 pmol/l to a higher peak of 133±7 pmol/l at 60 min. Glucose dependent insulinotropic polypeptide concentrations were significantly higher in Type 2 diabetic patients compared with the normal subjects at 30 min (p<0.001), 60 min (p<0.01) and from 210–240 min (p<0.05) during the meal tolerance test. The groups were subdivided on the basis of degree of obesity and glucose dependent insulinotropic polypeptide concentrations were still higher in the diabetic subgroups compared with the normal subjects matched for weight. Type 2 diabetes mellitus is associated with an exaggerated glucose dependent insulinotropic polypeptide response to oral glucose and mixed meals which is independent of any effect of obesity.     

基于文本挖掘技术探测胰岛淀粉样多肽的研究趋势

胰岛淀粉样多肽是2型糖尿病的重要致病原因之一.为了研究胰岛淀粉样多肽的生物学作用及其应用范围,本文拟通过文本挖掘技术来对胰岛淀粉样多肽生化用专业试剂和试剂盒检测的研究发展趋势进行探测.     

GIPR expression in gastric and duodenal neuroendocrine tumors

Background

Compounds targeting somatostatin-receptor-type-2 (SSTR2) are useful for small bowel neuroendocrine tumor (SBNET) and pancreatic neuroendocrine tumor (PNET) imaging and treatment. We recently characterized expression of 13 cell surface receptor genes in SBNETs and PNETs, identifying three drug targets (GIPR, OXTR, and OPRK1). This study set out to characterize expression of this gene panel in the less common neuroendocrine tumors of the stomach and duodenum (gastric and duodenal neuroendocrine tumors [GDNETs]).

Methods

Primary tumors and adjacent normal tissue were collected at surgery, RNA was extracted, and expression of 13 target genes was determined by quantitative polymerase chain reaction. Expression was normalized to GAPDH and POLR2A internal control genes. Expression relative to normal tissue (ddCT) and absolute expression (dCT) were calculated. Wilcoxon tests compared median expression with false discovery rate correction for multiple comparisons.

Results

Gene expression was similar in two gastric and seven duodenal tumors, and these were analyzed together. Like SBNETs (n = 63) and PNETs (n = 51), GDNETs showed significant overexpression compared with normal tissue of BRS3, GIPR, GRM1, GPR113, OPRK1, and SSTR2 (P < 0.05 for all). Of these, SSTR2 had the highest absolute expression in GDNETs (median dCT 4.0). Absolute expression of BRS3, GRM1, GPR113, and OPRK1 was significantly lower than SSTR2 in GDNETs (P < 0.05 for all), whereas expression of GIPR was similar to SSTR2 (median 4.3, P = 0.4).

Conclusions

As in SBNETs and PNETs, GIPR shows absolute expression close to SSTR2 but has greater overexpression relative to normal tissue (21.1 versus 3.5-fold overexpression). We conclude that GIPR could provide an improved signal-to-noise ratio for imaging versus SSTR2 and represents a promising novel therapeutic target in GDNETs.     

动物内源性多肽CGA—N46抗菌谱及对动物细胞的作用

目的研究抗真菌肽CGA-N46的抗菌谱及对不同动物细胞的作用效果。方法采用微量稀释法测定CGA-N46对14种常见病原真菌的抗菌活性;采用分光光度法检测CGA-N46对红细胞的溶解作用,采用MTT法测定CGAN46对鸡胚成纤维细胞的毒性作用及对癌细胞的抑制作用。结果CGA-N46对光滑念珠菌、近平滑念珠菌、克柔念珠菌、热带念珠菌、白念珠菌具有抑菌活性,其MIC分别为4．0、4．0、0．5、1．0、1．0mg／ml;最小抑菌浓度的CGA-N46无溶血作用,对鸡胚成纤维细胞无毒性,但对肺癌A549细胞有抑制作用,72h最大抑制率为60．53％。结论CGA-N46多肽具有抗念珠菌作用,且具有抗癌潜力,而对正常细胞安全、无毒性。