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M C Appel

Publications and source records attributed to M C Appel.

47 records · Page 3Linked to original sources
PubMed1979

Spontaneous diabetes mellitus: reversal and prevention in the BB/W rat with antiserum to rat lymphocytes.

Injections of rabbit antiserum to rat lymphocytes reversed hyperglycemia in 36 percent of spontaneously diabetic rats (Bio Breeding/Worcester) and prevented diabetes in susceptible nondiabetic controls. These findings strengthen the hypothesis that cell-mediated autoimmunity plays a role in the pathogenesis of diabetes in this animal model that mimics many morpholigic and physiologic characteristics of human insulin-dependent diabetes mellitus.

Animals↗
PubMed1979

Adrenal gland involvement in mice with hereditary obesity and diabetes mellitus. Morphological studies.

The contribution of the adrenal gland to the development of the spontaneous syndrome of obesity and diabetes in Yellow-KK (Y-KK) mice was studied. Six-month old Y-KK mice exhibited hyperadrenocorticism and adrenal cortex enlargement. Light microscopic morphometric studies of Y-KK adrenals revealed an expanded volume of the adrenal cortex resulting from hyperplasia of zona fasciculata and reticularis cells. Ultrastructural studies revealed fewer lipid droplets, increased numbers of mitochondria and a more extensively developed Golgi system with zona fasciculata and reticularis cells. This cytological evidence of enhanced steroid biosynthetic and secretory activity was consistent with increased levels of plasma immunoreactive corticosterone. Structural and functional abnormalities of Y-KK adrenals were preceded by the development of obesity, hyperglycaemia and hyperinsulinaemia. It is unlikely, therefore, that the adrenal plays a casual role in the syndrome's pathogenesis, although, hyperadrenocorticism may be in part responsible for an exacerbation of the observed phenomena.

Adrenal Glands↗
PubMed1979

Spontaneous diabetes in the gnotobiotic BB/W rat.

To determine the influence of infectious agents on the initiation of diabetes in the spontaneously diabetic Bio-Breeding/Worcester (BB/W) rat, susceptible rats were raised in a germ-free environment. Between 2 and 3 mo of age, 3 of 12 pups became diabetic. Histologic examination of the pancreas revealed insulitis or end-stage islets. Culture and smears from various tissues were negative for bacteria or parasites. Serum vital antibody titers for all known rat viruses were undetectable. These data suggest that the diabetic syndrome of the BB/W rat is not dependent on recognized infectious agents.

Animals↗
PubMed1978

Viral studies in streptozotocin-induced pancreatic insulitis.

Multiple injections of streptozotocin to Charles River (CD-1) Laboratory mice resulted in a syndrome characterised by diabetes mellitus, insulitis and the induction of endogenous type C viruses in pancreatic beta cells. Within one week after the completion of five intraperitoneal injections of streptozotocin, the CD-1 mice exhibited irreversible hyperglycaemia and insulinopaenia. Light microscopic studies of pancreata from mice sacrificed at this time demonstrated insulitis and beta cell necrosis. Electron microscopic studies revealed spherical and atypical cylindrical type C viruses and occasional clusters of intracisternal type A viruses exclusively within beta cells. To clarify the identification of the type C viruses and their role in the genesis of the insulitis, type C virus specific antigens were identified within islet cells by immune fluorescence at various intervals after streptozotocin administration. Immune fluorescence studies demonstrated the presence of type C virus antigens within islets from streptozotocin treated mice but not in buffer-injected controls. Time course studies suggested that type C virus induction may precede the appearance of insulitis by two days and that insulitis is consistently accompanied by the presence of virus positive islet cells.

Animals↗
PubMed1978

Sex differences in the multiple-dose streptozotocin model of diabetes.

The hyperglycemic response to multiple low-dose SZ injections was measured in castrated and non-castrated male and female mice with or without testosterone treatment. On the 10th day of the experiment, control males had plasma glucose concentrations that were significantly higher than those of control females. Castration of males decreased the hyperglycemic response, while testosterone treatment restored it. The glucose concentrations in castrated females were significantly greater than control females, but not different from castrated males. Testosterone administration to castrated or non-castrated females increased the hyperglycemic response to that seen in control males and in testosterone-treated castrated males. Thus, castration negates the sex difference in the hyperglycemic response to the multiple low-dose SZ injections. Testosterone enhances the hyperglycemic response in castrated or non-castrated females, and in castrated males.

Animals↗
PubMed1978

Streptozotocin-induced pancreatic insulitis in mice. Morphologic and physiologic studies.

Pancreatic insulitis and diabetes mellitus were induced in Charles River CD-1 mice with five subdiabetogenic injections of streptozotocin. Plasma glucose and immunoreactive insulin levels were measured and animals were sacrificed at intervals for morphologic studies of pancreatic islets and measurements of extractable pancreatic immunoreactive insulin. Light microscopy revealed striking insulitis, 5 to 6 days after streptozotocin injections, with cell necrosis and eventual islet atrophy due to beta-cell necrosis, and numerous type C viruses within many of the surviving beta-cells. Light microscopic immunoperoxidase stains of islet cell hormones and electron microscopy identified relatively increased numbers of alpha- and delta-cells within the atrophic islets 6 and 12 months after streptozotocin injections. Plasma glucose, plasma immunoreactive insulin, and extractable pancreatic immunoreactive insulin measurements documented the persistence of profound hyperglycemia, as well as the reduction of plasma and pancreatic immunoreactive insulin levels. Immunofluorescence studies demonstrated the absence of circulating islet cell antibodies during both the acute and chronic stages of the syndrome. The pathogenesis of this model of insulin-deficient diabetes is believed to be a cell-mediated autoimmune reaction directed against pancreatic beta-cells altered by subdiabetogenic injections of streptozotocin. The importance of the increased number of type C viruses within surviving beta-cells remains obscure.

Animals↗
PubMed1977

Studies of streptozotocin-induced insulitis and diabetes.

Multiple small injections of streptozotocin produce a delayed, progressive increase in plasma glucose in mice within 5-6 days after the injections, in association with pronounced insulitis and induction of type C viruses within beta cells. Multiple subdiabetogenic doses of streptozotocin in rats and multiple injections of another beta cell toxin, alloxan, in mice did not induce insulitis although hyperglycemia followed the injection of larger quantities of both agents. In mice, the prior injection of 3-O-methyl-D-glucose (3-OMG) or nicotinamide attenuated the diabetic syndrome produced by streptozotocin; however, 3-OMG was more protective. Rabbit antimouse lymphocyte serum, alone, provided partial protection but, when given together with either 3-OMG or nicotinamide, effectively prevented the streptozotocin-induced diabetic syndrome. Cessation of these preventive treatments was followed by the appearance of insulitis and diabetes. These findings suggest that multiple injections of streptozotocin induce, in susceptible hosts, the triad of direct beta cell cytotoxicity, virus induction within beta cells, and cell-mediated autoimmune reaction. These factors, acting separately or in concert, appear to induce a destructive insulitis and severe diabetes. The relative importance of each component and the factors governing host susceptibility remain to be clarified.

Animals↗
PubMed1977

Genetic influence of the streptozotocin-induced insulitis and hyperglycemia.

Multiple injections of subdiabetogenic doses of streptozotocin (SZ) to CD-1 male mice produce a diabetic syndrome that includes a cell-mediated immune reaction against the pancreatic islet. The importance of the host genetic background in the pathogenesis of this model of diabetes was studied by comparing various inbred strains of mice. Of eight strains of mice studied, only C57BL/KsJ developed insulitis and hyperglycemia comparable to that observed in CD-1 mice. In two mouse strains (DBA/J and BALB/cJ) having an H-2d haplotype similar to the C57BL/KsJ, only mild insulitis and glucose intolerance were observed. These data suggest that major histocompatibility complex genes, as presently defined, cannot be the only determinant of the severity of hyperglycemia and insulitis in this model.

Animals↗
PubMedDate not supplied

The effect of ciamexone on lymphocytic thyroiditis and insulin-dependent diabetes mellitus in the BB/Wor rat.

Previous studies have suggested that ciamexone, a 2-cyan-aziridine derivative, is a selective immunomodulatory agent with potential therapeutic application in a variety of autoimmune diseases. In the present study, the effects of ciamexone on autoimmune lymphocytic thyroiditis and diabetes mellitus were studied in the BB rat. The data suggest that, in this animal model, ciamexone does not affect the frequency of autoimmune diabetes or lymphocytic thyroiditis nor does it affect the serum TSH or T4 concentrations.

Adjuvants, Immunologic↗