糖尿病肾脏胶原非酶糖化与氨基胍阿斯匹林的治疗作用

本实验系统观察了ＳＴＺ所致糖尿病鼠在１、３、６个月后肾脏组织胶原发生非酶糖化的情况，及氨基胍、阿斯匹林对肾脏胶原非酶糖化的阻断作用。结果表明：各病程糖尿病动物肾组织的胶原含量和非酶糖化早期产物（５－ＨＭＦ）及胶原相联荧光值均明显高于正常对照。氨基胍能够减弱糖尿病动物肾组织胶原含量的增加和荧光产物的生成，但对５－ＨＭＦ含量无影响。阿斯匹林未显示出对胶原非酶糖化的影响。     

Biocompatibility pattern of a bicarbonate/lactate-buffered peritoneal dialysis fluid in APD: a prospective, randomized study.

BACKGROUND: In chronic ambulatory peritoneal dialysis, bicarbonate-buffered fluids, with their neutral pH and less advanced glycosylation end-products (AGE) and glucose degradation products (GDP), have better biocompatibility than conventional peritoneal dialysis (PD) solutions. That difference may be more beneficial in automated peritoneal dialysis (APD), due to its more frequent exchanges and longer contact times with fresh dialysate. We performed a prospective, randomized study in APD patients to compare the biocompatibility of conventional and bicarbonate/lactate-buffered PD fluids. METHODS: We randomized 14 APD patients to have APD with either conventional or bicarbonate/lactate-based fluids. After 6 months, both groups changed to the other solution. The overall observation period was 12 months. After 1 and 5 months and again after 7 and 11 months, phagocytotic and respiratory burst capacities of effluent peritoneal macrophages were determined. Plasma interleukin (IL)-6 and C-reactive protein (CRP) as well as effluent IL-6, CRP, transforming growth factor (TGF)-beta 1, AGE and CA125 concentrations were measured. Inflow pain was quantified using a patient questionnaire. RESULTS: Respiratory burst capacity remained unchanged and phagocytotic activity increased significantly during APD (P<0.001) with the bicarbonate/lactate fluid. Effluent IL-6 release was significantly lower than with the lactate fluid (P<0.05). While in the effluent TGF-beta 1 was unaffected, AGE concentration was lower after bicarbonate/lactate treatment (P<0.05). Effluent CA125 concentration, an indicator of mesothelial cell integrity, was higher (P<0.05) in neutral effluents. Finally, patients' inflow pain diminished (P = 0.05) when using the neutral fluid. CONCLUSIONS: The use of a neutral PD fluid in APD improved patients' inflow pain as well as biocompatibility parameters reflecting enhanced phagocytotic activity of peritoneal macrophages, reduced constitutive inflammatory stimulation (IL-6), reduced AGE accumulation in the peritoneal cavity and better preservation of the mesothelial cell integrity. From the biocompatibility point of view, a neutral fluid with low GDP content can be recommended as the primary choice for APD.     

Abnormal IgG galactosylation in MRL-lpr/lpr mice: pathogenic role in the development of arthritis

MRL-lpr/lpr (MRL/lpr) mice spontaneously develop arthritis by an increase in the incidence of agalactosylated oligosaccharides in serum IgG, similar to rheumatoid arthritis patients. However, whether this association has a pathogenic significance is still unknown. In this study, we analyzed the oligosaccharide structure of serum IgG in various MRL mice with or without arthritis, to clarify the relationship between the oligosaccharide abnormality and the development of arthritis. The level of agalactosylation in serum IgG was comparable in both arthritis-free MRL/lpr and MRL-+/+ (MRL/+) mice at 6 weeks of age. In contrast, the incidence of IgG lacking galactose markedly increased in MRL/lpr mice at 6 months of age (the age at which arthritis occurred), compared with that from age-matched MRL/+ mice without arthritis. However, the proportion of agalactosylated IgG increased similarly in anti-CD4 monoclonal antibody-treated MRL/lpr mice at 6 months of age, despite the absence of the development of arthritis, because of depletion of CD4+ T cells. These results suggest that the abnormality in IgG galactosylation of MRL/lpr mice developed in an age-dependent manner, but it did so independently of CD4+ T cell-dependent B-cell activation and is not a consequence of the development of arthritis.     

Identification of a frequent variant in ALG6, the cause of Congenital Disorder of Glycosylation-Ic

Congenital Disorder of Glycosylation (CDG) type Ic is caused by mutations in ALG6. This gene encodes an alpha1,3 glucosyltransferase used for synthesis of the lipid linked oligosaccharide (LLO) precursor of the protein N-glycosylation pathway. CDG-Ic patients have moderate to severe psychomotor retardation, seizures, hypotonia, strabismus, and feeding difficulties. We previously identified a typical patient with a heterozygous point mutation, c.391T>C (p.Tyr131His) in ALG6. Using complementation analysis of ALG6-deficient yeast, we show that this alteration is as severe as the most common disease-causing mutation, c998C>T (p. Ala333Val), which occurs in over half of all known CDG-Ic patients. The frequency of c.391T>C (p.Tyr131His) in the US population, is 0.0214, suggesting that homozygotes would occur at a rate of& tilde;1:2,200. We identified one patient with typical CDG-Ic symptoms and a homozygous p.Tyr131His alteration in ALG6. However, in contrast to most CDG patients, her LLO and plasma transferrin glycosylation appeared normal. Thus, it is unclear whether c.391T>C causes CDG-Ic or contributes to the symptoms. Genotyping additional patients with CDG-like symptoms will be required to resolve this issue.     

Non-enzymatic glycosylation in human diabetic lens crystallins

Summary Lens crystallins undergo non-enzymatic glycosylation with aging and diabetes mellitus. It is not known, however, whether all crystallins are subject to the same extent of glycosylation. Human diabetic lenses ( 80 years of age) were dissected into cortex and nucleus, then fractionated into various crystallins with gel chromatography (Sephacryl S-200, Sephdex G-75 or Bio Gel A-1 5m). The glycosylated crystallins were then separated from the nonglycosylated crystallins by affinity chromatography on Glyco Gel B boronic acid. The percentage of glycosylated crystallin was about 20–30%, and did not differ much among most crystallins, although -crystallin has significantly less (p < 0.01) glycosylated protein. The extent of glycosylation in the glycosylated crystallins, however, was found to be greater in the high molecular weight crystallins. The extent of glycosylation in -crystallins is approximately two to four times that observed in - or -crystallin. The extent of glycosylation appears to depend not only on the lysine content, which does not vary much among the crystallins, but also on the accessibility of the surface areas where lysine residues are located. This accessibility depends on the protein conformation and appears to correlate with protein unfolding.     

蛋白质非酶糖基化导致理化性状改变

目的观察蛋白质糖基化后理化特性的改变。方法牛血清白蛋白(BSA)与葡萄糖在体外共同孵育后,经聚丙烯酰胺凝胶电泳(PAGE)及荧光分光光度计测定荧光值和扫描荧光光谱。结果糖基化BSA荧光光谱改变,糖基化终产物(AGEs)荧光值增加;单体BSA在PAGE上向正极泳动加速,SDS-PAGE近负极段出现新的弥散带。结论蛋白质非酶糖基化可导致棕色变、阴电荷增加、分子量增大、荧光光谱改变。     

糖尿病大鼠视网膜微血管的重建及某些药物对其的影响

目的：研究糖尿病大鼠视网膜微血管的重建。方法：用链脲佐菌素（ＳＴＺ）诱导ＳＤ大鼠建立糖尿病动物模型,运用视网膜消化铺片和图像分析方法观测糖尿病大鼠视网膜微血管的重建,及非酶糖化抑制剂和活血化瘀中药对其重建的影响。结果：在８周时毛细血管宽度即有显著性变化（Ｐ〈０．０５）,非酶糖化抑制剂和活血化瘀中药治疗组在８～１２周后与糖尿病组有显著性差异（Ｐ〈０．０５）。结论：（１）糖尿病促进了视网膜微血管的形态     

Effect of advanced glycosylation end products on activity of protein kinase C in human peripheral blood mononuclear cells

Objectives To investigate the effect of advanced glycosylation end products (AGEs) on the a ctivity of protein kinase C (PKC) in human peripheral blood mononuclear cells (P BMC) and to observe whether aminoguanidine (AG) can influence the effect of AGEs .Methods After PBMC were isolated from human peripheral blood and incubated with differen t concentrations of AGEs-BSA for various periods, total PKC activity in PBMC wa s determined by measuring the incorporation of (32)P from ［γ-(32) P］ ATP into a special substrate using Promega PKC assay kit.Results AGEs-BSA increased the total PKC activity in PBMC from 83.43±6.57 pmol/min/ mg protein to 116.8±13.82 pmol/min/mg protein with a peak at 15 min. AGEs -BSA also increased the total PKC activity in a concentration-dependent manner fro m 83.1±6.4 pmol/min/mg protein (control) to 119.1±13.3 pmol/min/mg prote in (control vs AGEs-BSA 400 mg/L, P&lt;0.01).Furthermore, AGEs-BSA induc ed an elevation of PKC activity in a glycosylating time-related manner, from 80 .9±8.2 (control) to 118.3±11.5 pmol/min/mg protein (glycosylation for 12 wk, P&lt;0.01).The total PKC activity stimulated by AGEs-BSA pretreated wi th AG (100, 200 mg/L) was markedly lower than that of AGEs-BSA group not pretr eated with AG (P&lt;0.05, P&lt;0.01).Conclusions AGEs-BSA increased the total PKC activity in PBMC in a concentration and incuba tion time dependent manner. The ability of AGEs-BSA to stimulate PKC activity was markedly decreased by pretreatment of AGEs-BSA with AG.     

止消通脉宁对糖尿病大鼠肾脏胶原非酶糖化的影响

采用STZ糖尿病大鼠模型 ,在 6 ,12周分别观察肾脏组织发生非酶糖基化的情况 ,并观察止消通脉宁及氨基胍的作用。结果发现不同病程STZ糖尿病大鼠肾脏组织的胶原含量和非酶糖基化早期产物 (5 HMF)及胶原相联荧光值均明显高于正常对照组 ,并随病程的延长而增高。止消通脉宁有阻断肾脏组织非酶糖基化的作用 ,而对 5 HMF的作用优于氨基胍。说明高糖环境下肾脏组织可发生非酶糖基化 ,止消通脉宁有抑制肾脏组织非酶糖基化的作用 ,是其防治糖尿病肾病的作用机理之一     

2型糖尿病患者非酶促糖化低密度脂蛋白与血糖和血脂的关系

目的：分析２型糖尿病患者非酶促糖化低密度脂蛋白形成与血糖和血脂的关系,以及对胆固醇代谢的影响。方法：随机选择５２例２型糖尿病患者和１７例非糖尿病患者对照,测定其空腹血中血糖、血清甘油三酯、总胆固醇、低密度脂蛋白胆固醇、β脂蛋白浓度以及糖化低密度脂蛋白指数。结果：糖化低密度脂蛋白指数与血糖、血清甘油三酯、β脂蛋白、总胆固醇以及低密度脂蛋白胆固醇均呈线性正相关,其相关系数分别为ｒ＝０．８７０（Ｐ＜０．０５）,ｒ＝０．９３８（Ｐ＜０．０５）,ｒ＝０．９２（Ｐ＜０．０１）,ｒ＝０．９９３（Ｐ＜０．０５）和ｒ＝０．９９９（Ｐ＜０．０００５）。结论：高血糖和高甘油三酯血症可促使低密度脂蛋白高糖化形成,进而可干扰胆固醇代谢,导致低密度脂蛋白胆固醇以及总胆固醇浓度升高。