Lymphoid cells of BB/W diabetic rats are cytotoxic to islet beta cells in vitro

Assays were developed to detect cell-mediated immune destruction of pancreatic islet beta cells by lymphoid cells isolated from diabetic BioBreeding/Worcester (BB/W) rats. Splenic lymphoid cells from diabetic (D), diabetes-prone (DP), and diabetes-resistant (DR) BB/W rats were incubated for 2 days with monolayer cultures of major histocompatibility complex (MHC)-compatible Wistar-Furth (WF) rat islet cells or a rat islet cell line (RIN), and islet beta cell survival was determined by measuring insulin content in the cultures. D splenic lymphoid cells significantly decreased insulin content in WF rat islet (-32%) and RIN cultures (-77%). DP cells also significantly reduced the insulin content in WF rat islet (-20%) and RIN cultures (-63%), whereas DR cells had no significant effect. Islet-directed cytotoxicity was detected also by the release of 51Cr from RIN cells incubated for 8 h with BB/W spleen cells. Cytotoxicity was linearly related to the number of effector spleen cells. At a target: effector of 1:20, lysis (mean +/- SEM) of RIN target cells by spleen cells from D rats (21.6 +/- 2.0%) and DP rats (16.5 +/- 4.1%) was significantly greater than the effect of DR spleen cells (5.4 +/- 1.0%). D and DP splenic lymphoid cells activated in vitro for 2 days with concanavalin A exhibited a doubling of cytotoxicity to RIN islet cells. These results provide direct evidence for lymphoid cell-mediated immune damage to islet beta cells in diabetic BB rats.     

Analysis of c-Ki-ras mutations in human colon carcinoma by cell sorting, polymerase chain reaction, and DNA sequencing

We have analyzed colon carcinomas by a combination of histological enrichment, cell sorting, polymerase chain reaction, and direct sequencing of the c-Ki-ras-2 gene. DNA was chemically extracted from 50-microns sections of paraffin-embedded colon carcinomas and amplified in vitro, and mutations were documented directly by DNA sequencing. Enrichment for tumor cells was obtained histologically and by sorting nuclei on the basis of DNA content differences. Mutations in codon 12 were present in both aneuploid and diploid subpopulations of sorted carcinomas, suggesting that these mutations precede ploidy alterations in the progression of these neoplasms. We have demonstrated the feasibility of utilizing DNA from tissues treated with different fixatives, including methyl carnoys, formalin, and Hollande's solution. This procedure allows one to retrospectively reconstruct the temporal relationship between the occurrence of mutations and sequential morphological changes during tumorigenic progression.     

Iliac artery-ureteral fistula developing after dilatation and stent placement

A fistula formed between the common iliac artery and the ureter following balloon dilatation of the distal ureter and stent placement in the presence of an ileal conduit. Possible causes are discussed.     

Interleukin-1 inhibits glucose-modulated insulin and glucagon secretion in rat islet monolayer cultures

Recent observations suggest a role for interleukin-1 (IL-1), a polypeptide product of macrophage/monocytic cells, in the immune-mediated destruction of pancreatic islet beta-cells observed in type 1 diabetes. In this study, we investigated the effects of IL-1 on both alpha- and beta-cell secretory functions in rat islet cell monolayer cultures. Insulin release was 97% inhibited after 6 h of incubation in RPMI-1640 medium (11 mM glucose) containing 1 U/ml IL-1 and 96% inhibited after 24 h of incubation in medium containing 0.1 U/ml IL-1. The cell content of insulin in the monolayers was decreased by 66% (P less than 0.01) after 4 days of incubation in 10 U/ml IL-1; however, after a further 8-day incubation in IL-1-free medium, cell insulin content recovered fully. In contrast, cell glucagon content was decreased by 77% (P less than 0.001) after 4 days of incubation in 10 U/ml IL-1 and did not recover after a further 8-day incubation in IL-1-free medium. After an 18-h preincubation in medium with 0.1 and 1 U/ml IL-1, insulin release responses to 16.7 mM glucose were abolished in 4-h incubations, whereas responses to 0.1 mM 3-isobutyl-1-methylxanthine were normal, and after a further 2 and 5 days of incubation in IL-1-free medium, insulin responses to 16.7 mM glucose recovered fully. Similarly, the inhibitory effect of 16.7 mM glucose on glucagon release was lost after an 18-h preincubation in 0.1 and 1 U/ml IL-1, and did not recover fully after 2 and 5 days in IL-1-free medium, whereas the stimulatory effect of 3-isobutyl-1-methylxanthine on glucagon release was not affected by IL-1. We conclude that 1) IL-1 inhibits glucose-dependent and not cAMP-dependent mechanisms of insulin and glucagon release; 2) inhibition of glucose-stimulated insulin release by IL-1 is reversible, whereas the effect on glucose-modulated glucagon release is not; and 3) IL-1 causes a reversible decrease in the insulin content of islet cells and an irreversible decrease in glucagon content. These actions of IL-1 do not appear to account for the beta-cell-specific destruction of islets characteristic of type 1 diabetes.     

Structure and function of the pulmonary vascular bed: an update

This article discusses recent information regarding the normal and abnormal structural maturation of the pulmonary vascular bed, features that govern the functional behavior of the pulmonary circulation. Special emphasis is given to the cell biology of the vessel wall.