Yeast Exoglycoproteins Produced Under NaCl-Stress Conditions as Efficient Cryoprotective Agents

Six extracellular yeast glycoproteins were prepared from three yeast species in osmotic equilibrium and unequilibrium environments and used as non-penetrating cryoadditives. Glycoproteins secreted by the strain Dipodascus australiensis into growth medium containing NaCl (8% w/v) were found to be the most effective cryoadditives. It was possible to use these glycoproteins alone (without DMSO as penetrating agent) for the cryoprotection of the studied yeasts

A study of the growth of transplantable tumors in alloxanized Wistar rats

Blood sugar levels, and tumor size and incidence were determined for alloxanized Wistar rats bearing subcutaneous and intraperitoneal transplants of Novikoff hepatoma and Walker 256 carcinoma, and histological examination of the pancreas was undertaken to determine the extent of the damage to the beta-cells of the islets of Langerhans. Experiments were conducted in which animals were alloxanized 14 days, 7 days, 4 days, and 24 hours prior to, and 24 hours and 4 days after transplanting. The incidence and rate of growth of intraperitoneal tumors was appreciably decreased, and the rate of growth of subcutaneous tumors was slightly decreased in alloxanized animals, as compared with tumor-bearing controls. In tumor-bearing alloxanized animals, the high blood sugar levels characteristic of alloxan-diabetes were reduced to normal in some animals, and considerably ameliorated in others, as compared with alloxan-diabetic controls. Intraperitoneal tumors were more effective than subcutaneous tumors in reducing blood sugar levels, and relief was more pronounced in animals alloxanized just before or after transplanting than in those alloxanized two weeks before transplanting. Histological examination indicated that intraperitoneal tumor tissue invading the pancreas of alloxanized rats exerted a protective or regenerative effect on the beta-cells of the islets of Langerhans, which are selectively destroyed by alloxan. The possible role of sulphydryl groups in the amelioration of alloxan-diabetes in tumor-bearing animals, and in the reduction of tumor size and incidence in alloxan-diabetic animals is discussed. This work was reported in part in Proceedings of the American Association for Cancer Research, 2;20, 1955.Science, Faculty ofBotany, Department ofZoology, Department ofGraduat

Inosine Protects Against the Development of Diabetes in Multiple-Low-Dose Streptozotocin and Nonobese Diabetic Mouse Models of Type 1 Diabetes

Inosine, a naturally occurring purine, was long considered to be an inactive metabolite of adenosine. However, recently inosine has been shown to be an immunomodulator and anti-inflammatory agent. The aim of this study was to determine whether inosine influences anti-inflammatory effects and affects the development of type 1 diabetes in murine models. Type 1 diabetes was induced either chemically by streptozotocin or genetically using the nonobese diabetic mouse (NOD) model. Mice were treated with inosine (100 or 200 mg kg(−1)d(−1)) and diabetes incidence was monitored. The effect of inosine on pancreas immune cell infiltration, oxidative stress, and cytokine profile also was determined. For the transplantation model islets were placed under the renal capsule of NOD mice and inosine (200 mg kg(−1)d(−1)) treatment started the day of islet transplantation. Graft rejection was diagnosed by return of hyperglycemia accompanied by glucosuria and ketonuria. Inosine reduced the incidence of diabetes in both streptozotocin-induced diabetes and spontaneous diabetes in NOD mice. Inosine decreased pancreatic leukocyte infiltration and oxidative stress in addition to switching the cytokine profile from a Th1 to a Th2 profile. Inosine prolonged pancreatic islet graft survival, increased the number of surviving β cells, and reduced the number of infiltrating leukocytes. Inosine protects against both the development of diabetes and against the rejection of transplanted islets. The purine exerts anti-inflammatory effects in the pancreas, which is its likely mode of action. The use of inosine should be considered as a potential preventative therapy in humans susceptible to developing Type 1 diabetes and as a possible antirejection therapy for islet transplant recipients