Hemostatic risk factors of coronary artery disease in the Chinese

Induction of the mitochondrial permeability transition in vitro is well-characterized and widely implicated in the mechanism of oxidant-induced cell death. Despite an abundance of in vitro evidence, implication of mitochondrial dysfunction in the mechanism of chemical toxicity in vivo awaits demonstration of the induction of the mitochondrial permeability transition in tissues from intoxicated animals. Menadione (2-methyl-1,4-naphthoquinone), an agent known to induce the permeability transition in isolated liver mitochondrial in vitro, was administered as a single bolus to adult male rats, and hepatic mitochondria were isolated 24 h later. Mitochondria from menadione-treated rats exhibited an increased sensitivity to calcium-induced inhibition of state 3 respiration and loss of respiratory control, as well as a greater sensitivity to calcium-induced calcium release that was inhibited by cyclosporine A. Associated with this was the depolarization of membrane potential and swelling of mitochondria from menadione-treated animals, but not control animals. Both the calcium-dependent depolarization and swelling of mitochondria from menadione-treated rats were inhibited by adding either cyclosporine A or ruthenium red. The results are consistent with the induction of the mitochondrial permeability transition and provide the first evidence for the manifestation of an increased sensitivity to this response as a result of chemical exposure in vivo.     

High resolution mapping of the renal sodium-phosphate cotransporter gene (NPT2) confirms its localization to human chromosome 5q35

The precise chromosomal localization of the type II renal-specific Na+-phosphate (Pi) cotransporter (NPT2) gene (gene symbol SLC17A2) is necessary for the identification of closely linked polymorphic markers to determine whether NPT2 is a candidate gene for inherited disorders of renal Pi reabsorption. Recent studies by two different groups localized NPT2 to human chromosome 5q35 and 5q13, respectively. To resolve this discrepancy, we used three independent methods. The results using a human chromosome 5/rodent somatic cell hybrid deletion panel, fluorescence in situ hybridization with a PAC clone containing the NPT2 locus, and analysis of a chromosome 5-specific radiation hybrid panel were all consistent with the 5q35 assignment of the NPT2 gene. The radiation hybrid results placed NPT2 between polymorphic microsatellite markers D5S498 and D5S469. These findings will allow the initiation of linkage analysis to determine if NPT2 has a causative role in Mendelian disorders of renal Pi wasting.     

Monosialoganglioside (GM1) immunofluorescence in rat spinal roots studied with a monoclonal antibody

The rate of reaction of monochlorobimane with glutathione (GSH) was measured in native human mammary MCF-7 adenocarcinoma cells (MCF-7wt) and sublines displaying resistance to 4-hydroperoxycyclophosphamide (MCF-7hc) and adriamycin (MCF-7adr) prior to examination by epifluorescence and confocal microscopy. After a 60-min incubation period at 37 degrees C, essentially all GSH was conjugated in the MCF-7wt and MCF-7adr cell lines whereas only 80% of the GSH was conjugated in the MCF-7hc line. All three lines displayed significant export of the conjugate from the cell during this period, with the MCF-7adr line displaying the most rapid efflux with 85% of the conjugate exported within 60 min. Epifluorescence microscopy detected an approximately 20% increase in integrated fluorescence intensity in the nuclear region in all three lines. Confocal microscopy however, indicated that most of the cells examined showed a homogeneous fluorescence distribution. The cells grown in monolayers were found to be thicker in the nuclear region suggesting that the observed increase in fluorescence intensity in the nuclear region in the images from epifluorescence microscopy was probably derived from fluorescence from an out-of-focus plane. Cells depleted of GSH with buthionine sulfoximine followed by treatment with mBCl showed significant fluorescence intensity resulting from nonspecific binding of this probe. These studies illustrate the need for measuring the rate of GSH conjugate export and for determining probe specificity, and emphasizes the need for using confocal techniques for the quantitative evaluation of the distribution of intracellular fluorescence.     

Clinical observation of the temporal association between crack cocaine and duodenal ulcer perforation

HYPOTHESIS: To determine if a cause-effect relationship exists between crack cocaine use and duodenal ulcer perforation (DUP). PATIENTS AND METHODS: A retrospective study was conducted of all patients undergoing emergency surgical management for peptic ulcer disease over a 6-year period at a large inner-city municipal teaching hospital. The hospital records of 78 consecutive patients presenting with complications of peptic ulcer disease between April 1990 and April 1996 were reviewed. Group A (n = 24) consisted of patients with confirmation of crack cocaine usage within 8 hours of clinical presentation; group B (n = 54) consisted of patients with no antecedent history of crack cocaine use. Demographic data, timing of drug use, clinical presentation, laboratory and radiographic findings, toxicology screening, operative findings, and postoperative course were compared between the two groups. RESULTS: Both groups revealed a similar gender distribution, tobacco use, prior peptic ulcer symptoms, and laboratory findings. Group A patients were younger (t test, P = 0.01) and more likely to present with perforation, whereas patients in group B presented with a combination of symptoms (chi square, P = 0.03). Duodenal ulcer perforation was present in 75% of patients in group A compared with 46% of patients in group B (chi square, P = 0.04). Group B patients had a significantly longer hospital stay compared with those in group A (t test, P = 0.01). Both crack cocaine and alcohol are independent predictors of duodenal ulcer perforation. CONCLUSIONS: Patients with recent use of crack cocaine and/or alcohol are more likely to present with duodenal perforations. Although a temporal association between crack cocaine use and duodenal ulcer perforation was demonstrated, this study does not confirm a cause-effect relationship. A prospective cohort study is needed to clarify the pathogenesis of this potential cause-effect relationship.