Light and electron microscopic examination of organs of rats rendered hyperglycemic with streptozotocin revealed the following: (1) rapid degranulation of beta cells without necrosis; (2) development of cataracts in four months after injection of 65 mg. per kilogram of the drug; (3) accumulation of glycogen in the proximal convoluted tubules of the kidney after 65 mg. per kilogram; (4) lesions in the exocrine cells of the pancreas after 100 mg. per kilogram; and (5) persistence of small, possibly secretory, granules in the Golgi zone of beta cells in diabetic rats. The significance of these findings is discussed.
Several workers( 1-5) have reported data on rat mammary gland growth during pregnancy, a t parturition and during lactation. Changes in deoxyribonucleic acid (DNA) content have been used to indicate the period of rapid cellular proliferation (hyperpkia) , and ribonucleic acid (RNA) changes have been used to indicate both cellular enlargement (hypertrophy) and the periods of increased protein synthesis. The data reported for rat mammary gland tissue show general agreement in that the greatest increase in DNA occurs during pregnancy. The exact time a t which rapid proliferative growth starts, as measured by DNA content of the tissue is not exactly clear from the data presented. Reports by Kirkham and Turner( 1) and Shimizu(2) indicate that the increase in DNA occurs early in pregnancy, reaching a plateau after 10 days and increasing only slightly dulring lactation. Significant increases in DNA content, however, have been reported after parturition by Greenbaum and Slater (4) and Smith and Richterich(5). Tn those cases(2,3,4) where RNA content has been measured the greatest change has been shown to occur after parturition.We wish to report on some of oulr observations concerned with changes in guinea pig mammary gland during pregnancy, a t p rturition and during lactation. We have used the total weight of the gland, total nitrogen content and the nucleic acids (DNA and mined by 2 methods. In some cases the average nose to toe length of the extended fetuses was used. In most of our work the postpartum estrous period was used. After a sow gave birth, she was left with the male for 2 days and then was transferred, with her young, away from the male to an individual cage. About 70% of these females were found to be pregnant and this pregnancy could be timed within a day. For our colony the average nose to toe length of 4, 5 and 6 inches for the fetuses corresponded very closely to gestation times of 40, 50 and 60 days as measured by the postpartum estrous breeding method.Mammary glands were rapidly excised, chilled in cracked ice and then trimmed free of adhering tissue. They were then blotted, weighed, minced with scissolrs and homogenized in cold 0.25 M sucrose solution in an all glass homogenizer. Cellular pGLrticulates were isolated by differential centrifugation, essentially according to the method of Hogeboom, Schneider and Palade (6).Total nitrogen was determined by the Conway microdiffusion technic(7) on 0.05 to 0.1 ml aliquots of the homogenate after digestion with 0.4 ml of a digestion mixture containing concentrated sulphuric acid, 0.1 % selenium dioxide and 0.1% copper sulphste.Total nucleic acids and deoxyribonucleic acid were determined by the method of Ceriotti (8). Ribonucleic acid was then estimated RNA) as an index of mammary growth. by difference.
Materials and methods. MultiparousResults and discussion. Fig. 1 represents guinea pigs from our stack colony were used the growth and involution of the mammary in this study. Timed pregnancy was deter-gland in terms of the parameter's fresh weight, total ...
SYNOPSIS. Mitochondrial and supernatant fractions were isolated from Crithidia fasciculata by grinding with neutral alumina and differential centrifugation. Supernatant fractions contained at least 2 NAD‐linked enzymes: an α‐glycerophosphate dehydrogenase and a malate dehydrogenase. The properties of these enzymes were investigated polarographically with phenazine ethosulfate acting as electron acceptor. Agaricic acid, cinnamic acid and p‐NO2‐cinnamic acid were specific inhibitors of the α‐glycerophosphate dehydrogenase.
Succinate, malate, DL‐α‐glycerophosphate and NADH stimulated respiration of mitochondrial preparations; O2 uptake was greatest with succinate. KCN and antimycin A inhibited succinate respiration more than α‐glycerophosphate respiration. Amytal did not affect succinate, α‐glycerophosphate or NADH oxidation. The trypanocide suramin inhibited mitochondrial respiration at least 77% with each substrate. The relevance of these results to other members of the Trypanosomatidae is discussed.
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