Changes in the serum composition of free-fatty acids during an intravenous glucose tolerance test

Recent studies suggest that measuring the free-fatty acids (FFA) during an intravenous glucose tolerance test (IVGTT) may provide information about the metabolic associations between serum FFA and carbohydrate and insulin metabolism. We evaluated the FFA profile during an IVGTT and determined whether this test changes the composition and concentration of FFA. An IVGTT was given to 38 severely obese persons before and 7 months after undergoing bariatric surgery and also to 12 healthy, nonobese persons. The concentration and composition of the FFA were studied at different times during the test. The concentration of FFA fell significantly faster during the IVGTT in the controls and in the severely obese persons with normal-fasting glucose (NFG) than in the severely obese persons with impaired-fasting glucose (IFG) or type 2 diabetes mellitus (T2DM) (P < 0.05). Significant differences were found in the time to minimum serum concentrations of FFA (control = NFG < IFG < T2DM) (P < 0.001). These variables improved after bariatric surgery in the three groups. The percentage of monounsaturated and n-6 polyunsaturated FFA in the control subjects and in the obese persons, both before and after surgery, decreased significantly during the IVGTT. In conclusion, during an IVGTT, severely obese persons with IFG or T2DM experienced a lower fall in the FFA than the severely obese persons with NFG and the controls, becoming normal after bariatric surgery.     

Climate associated variations in the human serum albumin level

Summary Quantitative determinations of the human serum albumin level showed significantly higher values in tropical (Negroes 46.98 mg/ml, Indians 54.30 mg/ml) than in nontropical populations (Germans 44.41 mg/ml). These observations are in agreement with those of several other authors. It is assumed that these variations in the serum albumin level are related to climate, and that they may indicate some biological advantage of higher albumin levels under the climatic conditions of tropical biotops. This hypothesis is discussed considering several aspects.Supported by the DFG.     

Climate associated variations in the human serum albumin level.

Quantitative determinations of the human serum albumin level showed significantly higher values in tropical (Negroes 46.98 mg/ml, Indians 54.30 mg/ml) than in non-tropical populations (Germans 44.41 mg/ml). These observations are in agreement with those of several other authors. It is assumed that these variations in the serum albumin level are related to climate, and that they may indicate some biological advantage of higher albumin levels under the climatic conditions of tropical biotops. This hypothesis is discussed considering several aspects.     

Effect of repaglinide on endothelial dysfunction during a glucose tolerance test in subjects with impaired glucose tolerance

Background

Secondary treatment of arteriosclerosis may be applicable for the primary prevention of atherosclerosis in diabetic patients. This prospective, 2-year follow-up study was designed to determine the efficacy and safety of antiplatelet therapy in the prevention of atherosclerosis of diabetic subjects.

Methods

Patients with type 2 diabetes and arteriosclerosis obliterans from the Eastern Asian countries were registered online and randomly assigned either to the aspirin group (81–100 mg/day) or the cilostazol group (100–200 mg/day) in this international, 2-year, prospective follow-up interventional study.

Results

The primary study endpoint was changes in right and left maximum intima-media thickness of the common carotid artery. Secondary endpoints include changes in right and left maximum intima-media thickness of the internal carotid artery; semiquantitative evaluation of cerebral infarction by magnetic resonance imaging; cardiovascular events including sudden death, stroke, transient cerebral ischemic attacks, acute myocardial infarction, angina, and progression of arteriosclerosis obliterans; overall death; withdrawal; and change in ankle-brachial pressure index.

Conclusion

This is the first study to use an online system that was developed in Asian countries for pooling data from an international clinical trial. These findings are expected to help in the prevention of diabetic atherosclerosis and subsequent cardiovascular and cerebrovascular disease.     

胚胎发育早期接种人血清白蛋白诱导鸡的免疫耐受

外源基因的引入及表达常会引发宿主动物强烈的免疫应答,导致蛋白产量的下降或引起炎症反应。本研究试图通过在胚胎发育早期接种异源抗原诱导动物产生免疫耐受来解决这些问题。为了诱导鸡产生免疫耐受,将人血清白蛋白（Human serum albumin,HSA）通过胚胎血管微注射的方式接种到发育65—67h的鸡胚血管中,接种剂量为50μg;通过卵黄注射的方式接种到发育3—7d的鸡胚卵黄中,接种剂量为100μg。孵出的小鸡在3周龄时按照常规免疫方法再次接种同种抗原,收集不同时期的血清样本,用酶联免疫吸附试验（Enzyme-linked immunosorbent assay,ELISA）检测血清中抗-HSA抗体水平。结果表明,两种接种方式均能诱导小鸡产生免疫耐受：在65-67h的胚胎中通过血管微注射法接种抗原诱导小鸡产生免疫耐受的比率为64．52％;通过卵黄注射接种抗原诱导小鸡产生免疫耐受的最佳接种时间为发育的第6d,第5、7d接种对后期血清中抗-HSA抗体形成也有一定抑制作用,但是维持耐受的时间较短,第3、4d接种抗原对诱导小鸡免疫耐受的效果不明显[动物学报51（5）：845—851,2005]。     

Evaluating the glucose tolerance test in mice

The objective of this study was to determine the optimal conditions under which to assess glucose tolerance in chow- and high-fat-fed C57BL/6J mice. Mice were fed either chow or high-fat diet for 8 wk. Variables tested were fasting duration (0-, 3-, 6-, and 24-h and overnight fasting), route of administration (intraperitoneal vs. oral) load of glucose given (2, 1, or 0.5 g/kg and fixed 50-mg dose), and state of consciousness. Basal glucose concentrations were increased in high-fat- compared with chow-fed mice following 6 h of fasting (9.1 +/- 0.3 vs. 7.9 +/- 0.4 mmol/l P = 0.01). Glucose tolerance was most different and therefore significant (P = 0.001) in high-fat-fed mice after 6 h of fasting (1,973 +/- 96 vs. 1,248 +/- 83 mmol.l(-1).120 min(-1)). The difference in glucose tolerance was greater following an OGTT (142%), in contrast to an IPGTT, with a 127% difference between high fat and chow. We also found that administering 2 g/kg of glucose resulted in a greater level of significance (P = 0.0008) in glucose intolerance in high-fat- compared with chow-fed mice. A fixed dose of 50 mg glucose regardless of body weight was enough to show glucose intolerance in high-fat- vs. chow-fed mice. Finally, high-fat-fed mice showed glucose intolerance compared with their chow-fed counterparts whether they were tested under conscious or anesthetized conditions. We conclude that 2 g/kg glucose administered orally following 6 h of fasting is best to assess glucose tolerance in mice under these conditions.     

酵母表达重组人血清白蛋白检测方法的比较

应用生化法、电泳扫描结合Bradford法、竞争ELISA等3种方法检测酵母表达重组人血清白蛋白(rHSA)的表达量。结果表明,3种方法检测结果近似。比较而言,生化法灵敏度较低,但操作简便,价格低廉;竞争ELISA法灵敏度最高,但需要特异的抗体;电泳扫描结合Bradford法需要特殊仪器,操作繁琐,花费时间长,灵敏度介于生化法和竞争ELISA法之间。综合利弊,生化法可作为检测酵母表达rHSA的首选方法,如条件允许,可考虑采用电泳扫描结合Bradford法或竞争EUSA。     

Anion-binding centers of human serum albumin during an N-F conformation transition and in isolated albumin and blood serum

Fluorescent probe N-phenyl-1-amino-8-sulfonaphthalene (ANS) was used for studying pH-dependent structural N-F-transition in human serum albumin of two kinds: in commercial albumin and in natural blood serum. The kinetics of ANS fluorescence decay in albumin solutions was measured. There were found two types of the sites occupied by ANS in albumin under physiological conditions (pH 7.4). In the first binding site ANS fluorescence decay time was 16.6 +/- 0.3 nsec and it was not significantly changed at N-F transition (pH 4.0). In the second binding site the decay time was dependent on pH in commercial albumin and was not significantly changed in serum. In the second binding site there were individual differences of ANS decay time (4.3 +/- 0.6 nsec). The observed ANS fluorescence intensity enhancing (about 40-50%) in N-F transition may be explained by an increase of albumin binding sites capacity for ANS.     

Positive correlation of galanin with glucose in healthy volunteers during an oral glucose tolerance test.

Galanin has been found in increased amounts in subjects with type 2 diabetes. The purpose of the present study was to determine the levels of galanin in healthy volunteers during an oral glucose tolerance test (OGTT). We enrolled 11 healthy volunteers, 4 males aged 48+/-3.56 years with BMI 27+/-0.5 kg/m (2) and 7 females aged 41.3+/-3.05 years with BMI 27.6+/-0.9 kg/m (2). All were in good health without cardiac, hepatic, renal or other chronic disease. None were taking any medication affecting glucose tolerance (beta-blockers, thiazide diuretics, and corticoids) and none had a first degree relative with type 2 diabetes. Glucose tolerance was determined by using the International Expert Committee criteria. Blood samples were collected at 0, 30, 60, 90, 120 and 180 minutes for the measurement of plasma glucose, insulin, C-peptide and human galanin (hGal). During the OGTT, hGal exhibited a significant increase from time 0 to 90 minutes (p < 0.001) and returned to the basal values at 180 minutes, while a positive correlation of blood glucose with hGal was observed during the time scale of OGTT. A significant increase was detected both in insulin and C-peptide from the early beginning of the test at 30 minutes, which remained steady until 90 minutes, and returned gradually to the basal values at 180 minutes. No relationship was found either between hGal and serum insulin, or between hGal and serum C-peptide among the healthy subjects, during the OGTT.     

The extremely high level expression of human serum albumin in the milk of transgenic mice

The recombinant production of human serum albumin has been challenging due to the low unit price and huge amount needed, for the commercial production of rhSA at an economically feasible level, It will be well worth the effort to exploit new method for the extremely high level expression of rhSA. To this end, here a hybrid gene locus strategy was employed, a 37?Kb mWAP-hSA hybrid gene locus was constructed and used as mammary gland specific expression vector, in which the 3?Kb genomic coding sequence in the 24?Kb mouse whey acidic protein (mWAP) gene locus was substituted by the 16?Kb genomic coding sequence of human serum albumin (hSA), exactly from the start codon to the end codon. Corresponding transgenic mice were generated and rhSA was secreted into the milk at an extremely high level of 11.9?g/L. Our transgenic mice carrying the mWAP-hSA hybrid gene locus represent a model system for the cost-effective production of human serum albumin.     

Thermodynamic analysis of human serum albumin interactions with glucose: insights into the diabetic range of glucose concentration

The interaction of proteins with glucose results in their non-enzymatic glycation and influences their structural and functional properties. Human serum albumin (HSA) interacts with glucose forming glycated HSA. However, the glucose binding sites and the thermodynamic characteristics of the glycated HSA require further delineation. Here, the binding properties of HSA and glucose were studied utilizing fluorescent techniques. HSA was incubated with glucose in the 0-300mM range at 27 or 37 degrees C. The interaction of HSA with glucose showed two sets of binding sites. The first set consists of two sites with positive cooperativity and the second set consists of nine identical non-cooperative sites. The percentage of glycated HSA (gly%) and the moles of glucose bound to moles of HSA (r) were utilized to obtain binding constants and thermodynamic parameters based on the Wyman binding potential. The enthalpy of binding, obtained by van't Hoff relation, presented exothermicity up to 7mM glucose (126mg/dl, normal range) and endothermic propensity at higher glucose concentrations (>7mM, diabetic range). The start of endothermic propensity was consistent with the diabetic range of glucose concentration and indicates unfolding of HSA. The Gibbs free energy and entropy of binding further supports the unfolding of HSA. Therefore, glucose interacts with multiple sites on HSA affecting its biochemical and biophysical properties. This may interfere with HSA normal function contributing to diabetic complications.