The relationship of glycaemic level to advanced glycation end-product (AGE) accumulation and retinal pathology in the spontaneous diabetic hamster.

To assess the relationship between glucose and advanced glycation end products (AGE) and the relationship between AGE and retinal changes in vivo, we studied the time course of retinopathy over 12 months in trypsin digest preparations and measured glycaemia and retinal AGE in spontaneous diabetic hamsters of mild (MD) and severe (SD) phenotypes. Blood glucose levels were elevated in MD (9.44+/-0.76 mmol/l) and in SD (3 months: 24.3+/-1.4 mmol/l; 12 months: 31.7+/-0.8 mmol/l) over non-diabetic controls (NC: 7.15+/-0.25 mmol/l; p < 0.05 or less vs MD; p < 0.001 vs SD). Similar relations were found for HbA1. Retinal AGE in mild diabetes was 405+/-11.3 arbitrary units (AU) (NC 245+/-7.7; p < 0.01) after 3 months and remained unchanged. A non-linear increase of AGE over time was found in severe hyperglycaemic hamsters (466+/-21 AU after 3 months and 758+/-21 AU after 12 months; p < 0.001 vs MD). Pericyte loss in mild diabetes progressed from -26% after 3 months to 41% after 12 months (p < 0.001 vs NC). Whereas the initial pericyte loss in severely diabetic hamsters was identical to the mildly diabetic group, a higher degree of pericyte loss occurred after 12 months (-57%; p < 0.05 vs MD). Endothelial cell numbers remained unaffected by mild hyperglycaemia, but significantly increased over time in severe diabetes reaching 31.7% above controls after 12 months (p < 0.001 vs NC and MD). Microaneurysms were absent in all retinae examined. Acellular capillary segments were increased in mild diabetes (3.83+/-0.31 per mm2 of retinal area) and severe diabetes (7.83+/-0.73) over controls (1.0+/-0.23). These data suggest that a threshold of glycaemia might exist above which AGE removal systems become saturated. Pericyte loss and acellular capillary formation are associated with mild increases in blood glucose and AGE levels while endothelial cell proliferation requires higher glucose and AGE levels.

Loss of GLUT2 glucose transporter expression in pancreatic beta cells from diabetic Chinese hamsters.

The diabetic Chinese hamster is a well-established animal model for NIDDM with a defective glucose-induced insulin secretory response. In the pancreas of nondiabetic hamsters, the GLUT2 glucose transporter was localized in the plasma membrane of insulin-positive beta cells. At variance with the rat, immunoreactivity was also detected in the cytoplasm. Other islet cell types were not GLUT2 positive. GLUT2 immunoreactivity was already significantly reduced in beta cells from mildly diabetic animals in spite of a normal insulin immunoreactivity. In severely diabetic animals the majority of the beta cells had lost GLUT2 immunostaining. This observation was confirmed in a Western blot analysis of the GLUT2 protein in isolated pancreatic islets. Only beta cells that were densely immunostained for insulin were still GLUT2 positive. However, around 40% of the beta cells devoid of GLUT2 immunoreactivity were still insulin immunoreactive. Thus, the loss of GLUT2 immunoreactivity, which is an important component of the glucose recognition apparatus of the pancreatic beta cell, is an early indicator of beta cell dysfunction before the development of degenerative lesions or the loss of insulin immunoreactivity. GLUT2 loss may be important in the deterioration of glucose-induced insulin secretion in the diabetic Chinese hamster.

Generalized autoimmune disease in interleukin-2-deficient mice is triggered by an uncontrolled activation and proliferation of CD4+ T cells.

Interleukin-2-deficient mice (IL-2-/-) crossed to a BALB/c genetic background develop a lymphoproliferative syndrome with severe hemolytic anemia and die within 5 weeks of age. The presence of autoantibodies of various specificities and inflammatory lesions in several organs are indicative of a generalized auto-immune disease. No alterations of the immune system were observed in 6-day-old animals, but 10-day-old mice already showed an increased proliferation and polyclonal activation of lymphocytes. The treatment of IL-2-/- mice with anti-gp39(CD40L) antibody prevented the disease and indicated that the appearance of activated CD4- T cells (CD44high, CD69-) represents the first alteration of the immune system in IL-2-/- mice. Collectively, our results suggest that an essential role of IL-2 in vivo, which is not compensated by other cytokines, is the maintenance of self tolerance.

Efficiency of air filter sets for the prevention of airborne infections in laboratory animal houses.

Air filter sets (classes EU6 and EU9, or EU6 and S) were tested for their efficiency in protecting laboratory animals against potential airborne infections. Flexible-film isolators were used as a smaller scale model. In the first experiment, lasting 7 months, it was tested whether minute virus of mice (MVM) was able to penetrate the air filters between one isolator containing experimentally infected mice and another with MVM negative mice. In the second experiment we tested whether microorganisms in the incoming air were able to penetrate air filter sets. To assess this gnotobiotic mice in an isolator were monitored for 9 months for changes of their microbial flora. In both experiments a combination of EU6 and EU9 air filters proved to be sufficient to maintain the microbiological status of the animals. The same combination of medium efficiency filters (EU6 and EU9) is used on the air supply to 4 SPF-barrier units in which infections with MVM occurred repeatedly soon after the initial stocking. After a thorough disinfection no reinfection has been detected to date. This demonstrates that the relatively low efficiency of the air filters was not the cause of the repeated infection. The procedure for disinfection is described.

Class II MHC molecules and monocytes/macrophages in the respiratory system of conventional, germ-free and interferon-gamma-treated rats.

The localization of I-A-like class II major histocompatibility complex (MHC) molecules and cells of the monocyte/macrophage lineage was studied immunohistologically in the trachea and lungs of conventional, specified pathogen-free (SPF) and germ-free rats. In the three groups of animals I-A-like class II MHC molecules occurred in epithelia of the bronchus-associated lymphatic tissue (BALT), in B lymphocytes, in dendritic-shaped and elongated interstitial cells and in type II pneumocytes. Conventional and SPF rats were distinguished from germ-free animals only by the larger number of class II MHC-positive respiratory epithelial cells in the lower trachea and main bronchi. The distribution of monocytes/macrophages (ED1-positive cells) did not differ between the groups. After systemic treatment of SPF rats with interferon-gamma class II MHC molecules were newly induced in all respiratory epithelia and in the endothelium of large vessels. In addition, interferon-gamma sometimes led to pulmonary infiltration and caused class II-positive activated monocytes to accumulate in medium-sized pulmonary vessels and in alveolar capillaries. It is concluded that the microbial status does not qualitatively alter the distribution of class II MHC molecules and monocytes/macrophages in rat respiratory organs. Interferon-gamma can, however, provoke profound changes.

[The establishment of pathogen-free colonies of Chinese and Syrian hamsters (Cricetulus griseus and Mesocricetus auratus) by foster rearing]. / Versuche zum Aufbau pathogenfreier Kolonien von Chinesischen und Syrischen Hamstern (Cricetulus griseus und Mesocricetus auratus) durch Ammenaufzucht.

Naturally born (less than 5 d old) or hysterectomy-derived litters from 7 mice, 90 Chinese and 19 Syrian hamsters were fostered to conventional or gnotobiotic mouse, Chinese hamster or rat dams. Generally, Chinese hamsters and mice are able to serve mutually as foster mothers without special manipulations of dams or pups. Chinese hamsters adopted suckling mice with less problems than mice when fostering young hamsters. In correlation with sucking activity the growth of most of the mouse-fostered Chinese hamsters stopped during the first week after the pup exchange. During this phase only animals with high vitality could survive. When fostered by mice or rats, hysterectomy-derived (gnotobiotic) or newborn Chinese and Syrian hamsters survived only for few days. After initially intensive maternal care the hamster pups were increasingly neglected by the foster dams. This wellknown behavior is explained with the low sucking intensity of hamsters causing the decrease of the foster mother's maternal behaviour depending on the litter's stimuli. By this interaction between the mouse's maternity and the sucking behaviour of the hamster the success of the "classic" method of rearing gnotobiotic hamsters became highly chance dependent.