Alterations in basement membrane immunoreactivity of the diabetic retina in three diabetic mouse models.

BACKGROUND: The mouse retina contains three kinds of basement membrane (BM) structures; the inner limiting membrane (ILM), Bruch's membrane (BrM), and the BM surrounding the capillaries. We aimed to investigate possible variations of individual BM components and to detect effects caused by diabetes in three different diabetic mouse models. METHODS: After 4 and 6 months of diabetes (defined by blood glucose > 250 mg/dl), we analyzed by immunohistochemistry the laminin, collagen IV, and nidogen-1 and nidogen-2 protein composition of the BMs obtained from diabetic and non-diabetic Leptin-receptor deficient (db/db) mice and insulin receptor (IR)/insulin receptor substrate-1 (IRS-1) double heterozygous knockout mice. In addition, C57BL/6 J mice were rendered diabetic by intraperitoneal injections of streptozotocin (STZ). RESULTS: All analyzed BM proteins were detected in all of the three BMs with the exception of collagen IV, which was not detectable in the ILM of db/db mice and IR/IRS-1 mice. We present the first analysis of nidogen expression in diabetic BM. The staining patterns did not differ between the type-1 diabetic model (STZ) or the type-2 diabetic models (db/db and IR/IRS-1) and the wild-type controls, with only one exception: both the db/db mice and the IR/IRS-1 mice but not the STZ mice showed a decreased nidogen-1 immunoreactivity in the BrM after 4 months of diabetes, but not after 6 months. CONCLUSIONS: The BMs in the three mouse strains differ with regard to protein immunoreactivity in the inner limiting membrane. Changes in BM composition may affect both the assembly and the function of the retinal BM. However, there are no marked differences in the BM composition between type-1 and type-2 diabetes. These results provide evidence for BM remodelling during diabetic retinopathy.

Investigations on the life cycle and morphology of Tunga penetrans in Brazil.

In the present study, the life cycle of Tunga penetrans was established in Wistar rats in the laboratory, and the morphology of the resulting developmental stages was studied by means of light and scanning electron microscopy. It was seen that the females enter at a nonfertilized stage through the skin of their hosts. Only there the copulation occurs, while females and males brought together in a Petri dish showed no interest in each other. In any way -- fertilized or not -- the females start about 6 days after penetration and hypertrophy with the ejection of eggs. While fertilized eggs proceed to development, the unfertilized ones remain arrested. The eggs are ovoid and measure about 600 x 320 mum. The larvae hatch from the eggs 1-6 days (mean 3-4) after ejection. Formation of larvae 2 took at least another day, while 4 up to 10 days more were needed until this larva starts pupation (mean 5-7 days). The formation of the adult fleas inside the puparium occurred within 9-15 days (with a maximum hatch at day 12). Adult female fleas having reached the skin of a host start blood sucking within 5 min and prepare to enter the skin. After 24 h, the flea stacked already with two thirds of its body inside the skin. After 40 h, the penetration was completed, and feeding and hypertrophical enlargement started, which was completed on day 6, when eggs became ejected. When studying the morphology of the fleas obtained from different hosts, slight variations were seen, which, however, are not significant for a species separation but may be an indication of the presence of different strains/races or the beginning of such a formation.