[ ultrastructural effects of superovulatory drugs on mouse endometrial basement membrane]

The endometrial basement membrane has a major role in implantation of embryo. Studies have recently shown that the rate of successful implantation in stimulatory cycles is less than in normal cycle due to detrimental effect of superovulatory drugs on endometrium. To investigate the effect of stimulatory drugs on ultrastrucures of mouse endometrial basement membrane. The endometrial samples were obtained form 30 naturally pregnant mice [control group] and 30 syperovulated mice [experimental group] at the time of implantation [120 h after hCG injection]. Induced with PMSG [10 IU] and hCG [10 IU]. The specimens were processed for electron microscopic studies. Qualitative [based on electron density] and quantitative [thickness of basement membrane] studies were performed on micrographs. The data were analyzed using Mann-Whitney statistical test]. The qualitative observation of the case group revealed a well developed RER, increased number of mitochondria and high electron density of basement membrane. The quantitative data demonstrated that the thickness of basement membrane and lamina densa were significantly increased in the case group compared with control group [0.283 +/- 0.0777, 0.158 +/- 0.00827 vs. 0.239 +/- 0.0082, 0.155 +/- 0.0111, P< 0.05]. It can be concluded that superovulation drugs may lead to low implantation rate by changing the endometrial basement membrane

Regulation of Glomerular Endothelial Cell Proteoglycans by Glucose

The presence of heparan sulfate proteoglycan (HSPG) in anionic sites in the lamina rara interna of glomerular basement membrane suggests that the proteoglycan may be deposited by the glomerular endothelial cells (GEndo). We have previously demonstrated that bovine GEndo in vitro synthesize perlecan, a species of glomerular basement membrane HSPG. In this study we examined whether high glucose medium regulates the GEndo metabolism of glycopeptides including perlecan. Metabolic labeling of glycoconjugates with 35S-SO4, sequential ion exchange and Sepharose CL-4B chromatography of labeled glycoconjugates, and northern analysis were performed. Incubation of GEndo for 8 to 14 weeks (but not for 1-2 weeks) in medium containing 30 mM glucose resulted in nearly 50% reduction in the synthesis of cell layer and medium 35SO4-labeled low anionic glycoproteins and proteoglycans, including that of basement membrane HSPG (Kav 0.42) compared to GEndo grown in 5 mM glucose medium; no changes in anionic charge density or hydrodynamic size of proteoglycans were noted. Northern analysis demonstrated that the mRNA abundance of perlecan was reduced by 47% in cells incubated with 30 mM glucose. Our data suggest that high glucose medium reduces the GEndo synthesis of perlecan by regulating its gene expression. Reduced synthesis of perlecan by GEndo may contribute to proteinuria seen in diabetic nephropathy.

Extracellular matrix molecules as targets for brown spider venom toxins

Loxoscelism, the term used to describe lesions and clinical manifestations induced by brown spider's venom (Loxosceles genus), has attracted much attention over the last years. Brown spider bites have been reported to cause a local and acute inflammatory reaction that may evolve to dermonecrosis (a hallmark of envenomation) and hemorrhage at the bite site, besides systemic manifestations such as thrombocytopenia, disseminated intravascular coagulation, hemolysis, and renal failure. The molecular mechanisms by which Loxosceles venoms induce injury are currently under investigation. In this review, we focused on the latest reports describing the biological and physiopathological aspects of loxoscelism, with reference mainly to the proteases recently described as metalloproteases and serine proteases, as well as on the proteolytic effects triggered by L. intermedia venom upon extracellular matrix constituents such as fibronectin, fibrinogen, entactin and heparan sulfate proteoglycan, besides the disruptive activity of the venom on Engelbreth-Holm-Swarm basement membranes. Degradation of these extracellular matrix molecules and the observed disruption of basement membranes could be related to deleterious activities of the venom such as loss of vessel and glomerular integrity and spreading of the venom toxins to underlying tissues

Changes of glomerular basement membrane components in Vacor-induced diabetic nephropathy

OBJECTIVES: The thickening of the glomerular basement membrane in rats after Vacor ingestion was examined by electron microscopy. This study was performed to elucidate which biochemical components changed in the glomerular basement membrane after Vacor-induced diabetic glomerulopathy. METHODS: Immunohistochemical analyses of type IV collagen, laminin, fibronectin and chondroitin sulfate proteoglycan were performed. A single dose of Vacor (molecular weight 272), 80 mg/kg, was administered to adult male Wistar rats by orogastric canule, and the animals were sacrificed at 0.5, 1, 3, 7, 14, 28 and 56 days after administration. RESULTS: Mild thickening of the glomerular basement membrane was evident 7 days after Vacor administration, and the width of the glomerular basement membrane was more than twice that of normal controls at 28 and 56 days. Significantly increased expressions of type IV collagen, laminin, fibronectin and neutral polysaccharide in the thickened glomerular basement membrane were noted 14 to 56 days after administration, and a mildly increased expression of chondroitin sulfate proteoglycan appeared between 3 to 7 days. CONCLUSION: These abnormally increased glomerular basement membrane components might be part of what causes diabetic nephropathy after Vacor administration.

Disminución inducida por drogas del espesor de la membrana basal capilar en diabetes / Drug-induced decrease of muscle capillary basement membrane thickness in diabetes

Se realizaron tres biopsias musculares en 53 diabéticos no insulinodependientes durante un período de aproximadamente dos años. Al inicio 21 (40%) tuvieron un aumento en el espesor de la membrana basal capilar de músculo; 35 pacientes recibieron glipizida y 18 recibieron placebo. En los pacientes que recibieron placebo, la medida de espesor de la membrana basal capilar de músculo aumentó de 158,7 ñ 11,5 nm (SEM) a 170,9 ñ 14,7 nm (P = NS), pero en aquéllos que recibieron glipizida el valor disminuyó de 192,9 ñ 13,2 nm a 161,0 ñ 10,2 nm (P = 0,02). La glucosa plasmática y la hemoglobina glucosilada disminuyeron significativamente (P < 0,001) después de dos años en los pacientes que recibieron glicpizida. En 15, la media de la hemoglobina glucosilada A1 alcanzó un rango normal, mientras que el espesor medio de la membrana basal disminuyó a un nivel cercano al encontrado en sujetos sin diabetes (P = NS). Estos hallazgos concuerdan con la hipótesis de uqe la respuesta efectiva a la medicación oral puede disminuir el espesor de la membrana basal, sugiriendo que la microangiopatía diabética no es necesariamente progresiva