Evaluation of cholesterol absorption in rats using markers labeled with stable isotopes. Effect of complete bile diversion

BACKGROUND/AIMS: An easily performed method to measure cholesterol absorption with isotope labeled cholesterol and beta-sitostanol in humans is described. The first aim of the study was to show whether this method can also be used in rats. Secondly, to see whether complete bile diversion results in a complete loss of cholesterol absorption. METHODOLOGY: Cholesterol absorption was evaluated in rats by the constant isotope feeding method using [2H6]cholesterol and [2H4]sitostanol as markers. Fecal samples were analyzed by gas-chromatography/mass spectrometry. RESULTS: In 8 rats with intact enterohepatic circulation of bile acids, cholesterol absorption averaged 61 (3% (SD) (range: 54-69%)). Complete bile diversion was followed by an almost total loss of cholesterol absorption (5.5+/-0.6%, range: 2.4-6.9%, n=7). CONCLUSIONS: The results indicate that deuterated cholesterol and deuterated sitostanol are reliable markers for measurement of cholesterol absorption in rats and that bile acids are essential for cholesterol absorption.     

Benign and malignant cells in effusions: diagnostic value of image DNA cytometry in comparison to cytological analysis

Identifying tumor cells in body cavity fluids reliably is a well-known diagnostic problem. Since cytometric quantitation of nuclear DNA content appears to be a promising new tool in the diagnosis and prognostic evaluation of many solid human tumors, we examined its validity in detecting malignant cells in cytologically positive effusions. For this purpose, image DNA cytometric measurements, including the evaluation of DNA-ploidy and the calculation of the DNA index (DI), were performed in 80 body cavity fluids. The results were correlated with cytology, clinical course and final histological diagnoses. We used aneuploidy, as shown by interactive image DNA cytometry, as a marker for the malignancy of cells that occur in body cavity fluids with a 100% specificity and 94.8% sensitivity. Cytological investigation showed a 92.3% specificity and 95.4% sensitivity. Combining both methods raised the specificity to 100% and the sensitivity to 98.5% and had a positive predictive value of 100% and a negative predictive value of 93.8%. The DNA-index (DI) was significantly higher in malignant effusions than in benign effusions: 1.5 +/- 0.74 (mean +/- SD) versus 1.11 +/- 0.26 (p < 0.05). Along with the difficult cytological evaluation of malignant cells in body cavity fluids, image DNA cytometry can be a helpful additional method for evaluating these cells. Combining the two techniques results in a highly specific and sensitive prediction of malignant cells. We, therefore, suggest using these methods for the reliable identification of tumor cells in effusions.     

A novel isoform of the mitochondrial outer membrane protein VDAC3 via alternative splicing of a 3-base exon. Functional characteristics and subcellular localization

Voltage-dependent anion channels (VDACs) are pore-forming proteins found in the outer mitochondrial membrane of all eucaryotes. VDACs are the major pathway for metabolites through the outer mitochondrial membrane and, in mammals, bind several cytosolic carbohydrate kinases. Whereas yeast contain a single VDAC (YVDAC), to date three isoforms have been described in the mouse that constitute a gene family. We have observed an additional isoform of VDAC3 that appears to be generated via the tissue-specific alternative splicing of a 3-base exon (ATG). The exon is predicted to introduce a methionine 39 amino acids downstream of the amino terminus of the polypeptide. Between exons 3 and 4 is an intronic sequence that potentially encodes the exon, with flanking splice enhancer elements. Expression of this alternative form in the mouse is limited to brain, heart, and skeletal muscle. Complementation of YVDAC-deficient yeast by the two isoforms and with other sequence variants of VDAC3 suggests this residue is an important modulator of VDAC3 function. In transfected mammalian cells both isoforms localize to mitochondria. A similar variant is present in humans.     

Increased cutaneous toxicity to ionizing radiation in HIV-positive patients. Military Medical Consortium for the Advancement of Retroviral Research (MMCARR)

Little is known about the etiology of esophageal and gastric cardia adenocarcinoma (EGA), a cancer with one of the fastest-rising incidences in the developed world. To explore the etiology of this cancer, we conducted a retrospective cohort analysis using data from the Surveillance, Epidemiology and End Results Program of the United States National Cancer Institute to study EGA and esophageal squamous cell carcinoma (ESC), in association with cancers of other sites. Standardized incidence ratios, adjusted for age, sex, and time period, were calculated as a measure of the relative risk (RR) of developing a second primary cancer (EGA or ESC) following a given first primary site. We found a moderately elevated risk of EGA following cancers of the lung (RR = 1.9 in men and RR = 2.0 in women) and of the head and neck (RR = 2.1 in men and RR = 6.3 in women) and a strongly elevated risk of ESC following cancers of the lung (RR = 2.8 in men and RR = 5.1 in women) and of the head and neck (RR = 9.6 in men and RR = 38.8 in women). A significantly elevated risk following breast cancer in women was observed for both EGA (RR = 2.6; 95% confidence interval, 1.8-3.7) and ESC (RR = 1.4; 95% confidence interval, 1.1-1.9). We also found a significantly elevated risk of EGA following bladder (RR = 2.0), colorectal (RR = 1.7), and prostate (RR = 1.4) cancer in men and of ESC following colorectal cancer (RR = 1.7) in women in this study. The strong association with tobacco-related malignancies in this study reinforces the role of tobacco in the etiology of esophageal cancers, which appears stronger for squamous cell carcinoma than for adenocarcinoma and stronger in women than in men. The study also suggests a possible shared etiology between esophageal adenocarcinoma and colorectal cancer in men and provides new evidence about the association of both adenocarcinoma and squamous cell carcinoma of the esophagus with breast cancer in women. Findings of this study provide clues to the etiology of EGA and ESC.     

Gene structures and properties of enzymes of the plasmid-encoded nicotine catabolism of Arthrobacter nicotinovorans

Arthrobacter nicotinovorans is a Gram-positive aerobic soil bacterium able to grow on nicotine as its sole source of carbon and nitrogen. The initial steps of nicotine catabolism are catalyzed by nicotine dehydrogenase, the l- and d-specific 6-hydroxynicotine oxidases, and ketone dehydrogenase. The genes encoding these enzymes reside on a 160 kb plasmid, pAO1. The cccDNA of this plasmid was isolated in high purity and reasonable yield. It served as template material for the construction of a lambda-phage DNA library of the plasmid. The genes coding for 6-hydroxy-l-nicotine oxidase and for the subunits of the heterotrimeric ketone dehydrogenase were identified, subcloned and sequenced. The 6-hlno gene was identified as a 1278 bp open reading frame; its regulatory elements were also recognized. The derived primary structure of the monomer of apo-6-hydroxy-l-nicotine oxidase (46,264.5 Da) agrees with the data obtained by partial amino acid sequencing. 6-Hydroxy-l-nicotine oxidase and 6-hydroxy-d-nicotine oxidase were expressed in Escherichia coli and obtained in a state of high purity and crystallized. Ketone dehydrogenase (KDH) was found to be a heterotrimer with subunits of molecular mass 89,021.71, 26,778.65 and 17,638.88. The genes of KDH-A and KDH-B are juxtaposed; the A of the stop codon of KDH-A is used in the start codon of KDH-B, eliciting a frame shift. KDH-C is separated from KDH-A by 281 bp.     

Staphylococcus aureus pericarditis in HIV-infected patients

Serious infections caused by Staphylococcus aureus in HIV-infected patients have been reported. Contributing factors in the development of invasive S aureus infections include a high rate of skin and nasal colonization, frequent dermatologic disease, and the use of intravenous catheters. The authors report three cases of S aureus pericarditis in HIV-infected patients. While cases of viral, mycobacterial, and malignant pericardial effusions in HIV-infected patients have been reported, a review of the literature disclosed only three cases of bacterial pericarditis. Despite appropriate antibiotic therapy and drainage, a patient's condition may abruptly deteriorate and progress to tamponade. Early recognition of bacteremia and pericarditis and monitoring for cardiac tamponade, along with aggressive treatment, can result in a favorable outcome, but mortality remains high, particularly when S aureus is the causative agent.