Increased collagen around deformed finger nailfold capillaries in type I diabetes mellitus

Ultrastructural Changes in the Venous Wall Induced by Experimental Diabetes: Preliminary Findings

Objective:

To study whether experimental streptozotocin (STZ) induced diabetes results in structural alterations to the venous wall of the femoral vein in adult rats, in order to develop further studies using this model.

Design:

A prospective study of femoral veins obtained from controls and STZ-induced diabetes rats.

Setting:

Department of Morphology, Universidad de Las Palmas de Gran Canaria, Spain.

Interventions:

Experimental diabetes induced by intraperitoneal injection of streptozotocin.

Main outcome measures:

The samples were studied at 6 and 12 weeks post-injection using light and transmission electron microscopy.

Results:

The results show that the venous wall is affected by an increase in the deposition of extracellular tissue. In addition the endothelial, muscular and adventitial cells show morphological changes.

Conclusions:

Our results demonstrate significant alterations in the venous wall due to hyperglycaemia in the STZ-animal model.

Immunohistochemical and ultrastructural study of microvessels in diabetic veins

The aim of this study was to examine the localization and features of the intramural microvessels in the wall of inferior limb veins in diabetic patients. The study was conducted in a group of 10 insulin-dependent diabetic patients, who had suffered inferior limb amputation as a consequence of chronic limb ischemia. Sections of long saphenous and posterior tibial veins were investigated by light and transmission electron microscope. The von Willebrand factor and albumin were detected by immunohistochemical techniques. The results show the presence of numerous microvessels in the intima and inner third of the media layer of the venous wall of the sections studied. These microvessels present morphological and functional modifications in relation to those observed in the control veins. They also showed the presence of endothelial cells migrating from the lumen. The authors conclude that the venous wall of inferior limbs in amputated diabetic patients presents a neovascularization process. Some of the endothelial cells of the venous lumen can also have a role in the angiogenesis.

Plasma fluorescein binding and transcapillary fluorescein escape rate in renal failure associated with diabetes

Microvascular damage, often resulting in renal failure, is a common complication of diabetes. Transcapillary fluorescein escape rate (TCFER) as monitored by intravital microscopy has been used as an indicator of the extent of capillary damage in diabetes and to assess improvement in microvascular function after combined kidney-pancreas transplant. However, fluorescein anion binds to plasma albumin, and albumin-ligand binding may be altered in the presence of renal disease. The purpose of this study was to compare fluorescein binding by plasma from diabetics with renal failure with plasma from healthy nondiabetics. Fluorescein binding by plasma from seven type I diabetics awaiting kidney-pancreas transplant and seven healthy adults of similar age and sex was studied using ultrafiltration and dialysis. There was no significant difference in the apparent albumin binding of fluorescein at physiologically relevant fluorescein concentrations, even though the TCFER was significantly increased in the diabetics as compared with the controls. Hippurate, a ligand that accumulates in renal failure, did alter fluorescein binding in a defatted albumin solution but not sufficiently to account for the differences in TCFERs. These data indicate that impaired albumin binding of fluorescein does not contribute significantly to the TCFER in diabetics with renal failure.