Islet cell proliferation and apoptosis in insulin-like growth factor binding protein-1 in transgenic mice

Transgenic mice which overexpress insulin-like growth factor binding protein-1 (IGFPB-1) demonstrate fasting hyperglycemia, hyperinsulinemia and glucose intolerance in adult life. Here we have examined the ontogeny of pancreatic endocrine dysfunction and investigated islet cell proliferation and apoptosis in this mouse model. In addition we have examined pancreatic insulin content in transgenic mice derived from blastocyst transfer into non-transgenic mice. Transgenic mice were normoglycemic at birth but had markedly elevated plasma insulin levels, 56.2 +/- 4.5 versus 25.4 +/- 1.5 pmol/l, p < 0.001, and pancreatic insulin concentration, 60.5 +/- 2.5 versus 49.0 +/- 2.6 ng/mg of tissue, P < 0.01, compared with wild-type mice. Transgenic mice derived from blastocyst transfer to wild-type foster mothers had an elevated pancreatic insulin content similar to that seen in pups from transgenic mice. There was an age-related decline in pancreatic insulin content and plasma insulin levels and an increase in fasting blood glucose concentrations, such that adult transgenic mice had significantly less pancreatic insulin than wild-type mice. Pancreatic islet number and the size of mature islets were increased in transgenic animals at birth compared with wild-type mice. Both islet cell proliferation, measured by 5-bromo-2'-deoxyuridine labeling, and apoptosis, assessed by the in situ terminal deoxynucleotidyl transferase and nick translation assay, were increased in islets of newborn transgenic mice compared with wild-type mice. In adult mice both islet cell proliferation and apoptosis were low and similar in transgenic and wild-type mice. Islets remained significantly larger and more numerous in adult transgenic mice despite a reduction in pancreatic insulin content. These data suggest that overexpression of IGFBP-1, either directly or indirectly via local or systemic mechanisms, has a positive trophic effect on islet development.     

Evidence of sexual reproduction in the protozoan parasite Leishmania of the Old World

Three Leishmania strains of the old world were the subject of this study. Both the amastigote and promastigote stages were subjected to staining by Feulgen procedure and examined by computerized image analyser system to determine their nuclear DNA content. Results of this study showed that, in the promastigote stage there is a single cell population, whereas in the amastigote stage there are two population of parasite nuclei. One with low level of DNA resembling that of the promastigote and a second population with double DNA level. This latter formed when apparently 2 nuclei fused and form one with double DNA level. The data obtained in the present study further indicate that Leishmania of the old world can undergo nuclear fusion which is a strong evidence for the presence of sexual reproduction in the parasite.     

Ethical conflicts reported by registered nurse/certified diabetes educators: a replication

The purpose of this study was to identify types of ethical conflicts reported by certified diabetes educators who are also registered nurses (RN/CDEs) and to examine their relationship with demographic, educational and practice setting variables. This study is a replication of an earlier pilot study. Ethical conflicts expressed by RN/CDEs in active practice in New York and Pennsylvania were analysed according to four themes. Disagreement with medical practice was by far the most dominant clinical context for the conflicts (61%), as it had been in the pilot study (75%). Participants believed that 32% of the ethical conflicts were resolved. Ethics committees and consultants were very rarely used. Of the relationships between the kinds of conflicts and their resolution, and demographic, educational and practice setting variables of the participants, only kind of position was significantly (P < 0.005) related to practice context of the ethical conflict.     

The use of [18F]4-fluorobenzyl iodide (FBI) in PET radiotracer synthesis: model alkylation studies and its application in the design of dopamine D1 and D2 receptor-based imaging agents

[18F]4-Fluorobenzyl iodide ([18F]FBI) was prepared, and a series of model alkylation studies were conducted to determine its chemical reactivity toward nitrogen and sulfur nucleophiles of varying nucleophilicities. [18F]FBI was found to react rapidly with secondary amines and anilines to give the corresponding N-[18F]4-fluorobenzyl analogue in high yield. Amides and thiol groups required the use of a base catalyst. The utility of [18F]FBI was documented by investigation of dopamine D1 and D2 receptor-based radiotracers.     

Mechanism of hypoxic K loss in rabbit ventricle

Although a critical factor causing lethal ischemic ventricular arrhythmias, net cellular K loss during myocardial ischemia and hypoxia is poorly understood. We investigated whether selective activation of ATP-sensitive K (KATP) channels causes net cellular K loss by examining the effects of the KATP channel agonist cromakalim on unidirectional K efflux, total tissue K content, and action potential duration (APD) in isolated arterially perfused rabbit interventricular septa. Despite increasing unidirectional K efflux and shortening APD to a comparable degree as hypoxia, cromakalim failed to induce net tissue K loss, ruling out activation of KATP channels as the primary cause of hypoxic K loss. Next, we evaluated a novel hypothesis about the mechanism of hypoxic K loss, namely that net K loss is a passive reflection of intracellular Na gain during hypoxia or ischemia. When the major pathways promoting Na influx were inhibited, net K loss during hypoxia was almost completely eliminated. These findings show that altered Na fluxes are the primary cause of net K loss during hypoxia, and presumably also in ischemia. Given its previously defined role during hypoxia and ischemia in promoting intracellular Ca overload and reperfusion injury, this newly defined role of intracellular Na accumulation as a primary cause of cellular K loss identifies it as a central pathogenetic factor in these settings.     

Sensitivity to a metabolite of diclofenac as a cause of acute immune hemolytic anemia

A 75-year-old woman taking the nonsteroidal anti-inflammatory drug diclofenac (DCF) presented with acute Coombs-positive hemolytic anemia and subsequently developed renal failure. A drug-dependent antibody specific for red blood cells (RBCs) could not be demonstrated by in vitro testing with DCF. However, her serum was found to contain an IgM antibody that reacted strongly with RBCs in the presence of urine from any of four subjects who had ingested DCF. The active substance in urine was isolated, subjected to high-performance liquid chromatographic (HPLC) analysis, and found to be a glucuronide conjugate of a known DCF metabolite, 4'-hydroxydiclofenac (4'-OH DCF). Negative results were obtained with four other DCF metabolites. Two 4'-OH DCF glucuronides were synthesized in vitro using a liver microsomal system. One promoted agglutination of normal RBCs by the patient's serum and was identified as the glucuronide ester of 4'-OH DCF by proton nuclear magnetic resonance (NMR) analysis. Studies with a panel of RBCs showed that the patient's antibody reacted preferentially with the e antigen of the Rh system. Acute immune hemolytic anemia in this patient appears to have been caused by sensitization to DCF modified by 4' hydroxylation and glucuronidation. This is the first reported example of immune cytopenia caused by sensitivity to a glucuronide conjugate of a drug metabolite. Since glucuronidation is a common pathway of drug metabolism, studies of the frequency with which glucuronide derivatives of primary medications cause immune cytopenia seem warranted.