Effects of zinc deficiency on protein synthesis and expression of specific mRNAs in rat liver

The effects of zinc deficiency on protein synthesis and expression of specific mRNAs were assessed in rat liver. Zinc deficiency had no apparent effect on liver weight, protein content, or RNA content when these properties were compared with values obtained using pair-fed rats. However, zinc deficiency resulted in a lower rate of hepatic protein synthesis. The decreased rate of protein synthesis was due to a decrease in the rate of synthesis of proteins retained in the liver, with no apparent change in the synthesis of secreted proteins. Analysis of expression of specific gene products, as assessed by in vitro translation of total RNA followed by two-dimensional gel analysis, showed that the expression of only a few mRNAs was altered by zinc deficiency. The patterns of change in gene expression resulting from zinc deficiency varied from almost complete repression to full expression. In additional studies, cDNA clones to serum retinol-binding protein and transthyretin were used to examine the effect of zinc deficiency on the relative abundance of mRNA for these two proteins. The relative abundance of mRNA for transthyretin was specifically elevated as a result of zinc deficiency. In contrast, the relative abundance of mRNA for hepatic serum retinol-binding protein was increased in both zinc-deficient and pair-fed rats. Therefore, the observed change in mRNA for serum retinol-binding protein was apparently at least in part due to the inanition that accompanies zinc deficiency. Overall, the results suggest that zinc can regulate the synthesis of specific proteins in rat liver through changes in the relative abundance of specific mRNAs.     

Drastic reduction of topoisomerase II alpha associated with major acquired resistance to topoisomerase II active agents but minor perturbations of cell growth

V511 and V513 cell lines, derived from Chinese hamster V79 cells following alkylating agent mutagenesis and subsequent selection with VP-16, showed resistance to cytotoxicity and DNA strand breaks induced by topoisomerase (topo) II inhibitors and were resistant to VP-16-induced sister chromatid exchanges. They showed no amplification of the multidrug-resistant p-glycoprotein. In a kinetoplast-DNA decatenation assay, V511 and V513 showed 51% and 49% topo II activity relative to parental V79 cells, respectively. By western-blot analysis all three logarithmically growing cell lines showed similar levels of topo II beta (M(r) 180,000), which increased as cells progressed to quiescence. In contrast, immunoreactive levels of topo II alpha (M(r) 170,000) were 6.8% in V511 and 62.4% in V513 relative to V79. V511 showed drastically decreased topo II alpha in both log growth and quiescence. In a second approach, immunoreactive topo II was analyzed in different phases of the cell cycle in logarithmically growing cells fractionated by fluorescence-activated cell sorting. All cell lines demonstrated relatively stable topo II beta throughout the cell cycle. Topo II alpha showed little cell cycle variation in V79 or V513. However, in V511, it was only detectable at low levels in G2/M phase. When cell growth parameters were measured, V511 and V513 showed a 17% increase in cell doubling time relative to V79. These studies indicate that cells with a drastic reduction in topo II alpha (V511) or mutant topo II alpha (V513) but with normal levels of topo II beta show only minor perturbations of cell growth.     

Synergistic regulation of a neuronal chloride current by intracellular calcium and muscarinic receptor activation: a role for protein kinase C

Using perforated patch recordings in combination with intracellular Ca2+ ([Ca2+]i) fluorescence measurements, we have identified a delayed Ca(2+)-dependent Cl- current in a mammalian sympathetic ganglion cell. This Cl- current is induced by the synergistic action of Ca2+ and diacylglycerol (DAG) and is blocked by inhibitors of protein kinase C. As a result, the current can be induced by acetylcholine through the conjoint activation of nicotinic receptors (to produce a rise in [Ca2+]i) and muscarinic receptors (to generate DAG). This demonstrates an unusual form of synergism between the two effects of a single transmitter mediated via separate receptors operating within a time scale that could be of physiological significance.     

Inferior vena caval thrombosis associated with acute pancreatitis: an unusual vascular complication--its presentation and management

Vascular thrombosis and systemic hypercoagulable states are known complications of acute pancreatitis. They are thought to be secondary to the release of proteolytic enzymes of the pancreas. Inferior vena caval thrombosis is an extremely rare complication of chronic pancreatitis and has, to the authors' knowledge, never been reported in acute pancreatitis. The clinical presentation and radiographic findings are reviewed to illustrate the disease spectrum. Early treatment with intravenous heparin appears to be an effective therapy. Familiarity with this complication will aid physicians in its early diagnosis. However, a high degree of suspicion for this complication is necessary to make a diagnosis.     

Laparoscopic removal of gonads containing on occult seminoma in a woman with complete androgen resistance

Although nomograms to convert readings of resistance (R) and reactance (Xc) into estimates of body composition have begun to emerge for children as well as adults, there has been reluctance to use bioelectrical impedance analysis (BIA) in very young children due to the irritability of children, measurement instability, positioning of electrodes, and, of course, reproducibility of measurements. The precision of completely independent measurements of BIA indices was evaluated by two observers by comparing a series of 40 measurements of R and Xc and 36 measurements for weight in four malnourished children on 10 different days during the course of their nutritional recuperation. For weight, the CV (coefficient of variation) was 3.5% for observer A and 3.8% for observer B. There were no differences in the means across observers with respect to weight, R, and Xc. The results obtained in this study illustrate that properly trained observers following the same standards can produce equivalent data for BIA and weight measurements even in sick children.     

MRI-derived ventricular volume curves for the assessment of left ventricular function

To assess the utility of double oblique, ECG-gated 1H magnetic resonance (MR) derived volume curves for assessing LV function, cardiac short axis images were acquired with a fast field echo technique. We applied this methodology to assess left ventricular function in three groups: normals, patients with left ventricular hypertrophy, and dilated cardiomyopathy. Six slices with 16-20 phases per RR interval were analyzed, representing the initial 75-80% of the cardiac cycle. For each slice, the endocardial border of the left ventricular (LV) chamber was manually traced. Using Simpson's rule, the total LV volume at a given phase was determined considering the traced area, thickness and position in three-dimensional space of each of the six constituent slices. The calculated volumes were plotted against time and the stroke volume, ejection fraction and cardiac output were determined. The volume vs time plots for the systolic and diastolic portions of the curve were individually fit to third degree polynomials using a least squares approximation. From the fit curves, the following data were extracted: the mean slope (dV/dT) during filling and emptying, and the time to 1/4, 1/3 and 1/2 filling and emptying. These parameters are valuable indices of the functional status of the myocardium; thus, accurate and useful estimates of LV function can be obtained using MRI derived volume curves in normal and abnormal states.     

A mass spectrometric solution to the address problem of combinatorial libraries

The molecular weights of femtomole quantities of small peptides attached to polystyrene beads have been determined with imaging time-of-flight secondary ion mass spectrometry. The analysis is made possible by the selective clipping of the bond linking the peptide to a bead with trifluoroacetic acid vapor before the secondary ion mass spectrometry assay. The approach can be applied to large numbers of 30- to 60-micrometer polystyrene beads for the direct characterization of massive combinatorial libraries.     

Role of vacuolar adenosine triphosphatase in the regulation of cytosolic pH in hepatocytes

The almost exclusive media focus on political violence in South Africa has deflected attention from the high levels of interpersonal violence in areas of socioeconomic deprivation. In order to explore the tension between an at-risk community's perspective and the current reality of violence against women, imaginary constructions of their own violent death produced by 45 African female interview respondents were examined in conjunction with forensic data relating to 73 African female homicide victims in Cape Town, South Africa. The prototypical account of an imagined homicide involved a female commuter being approached by a group of men, taunted and assaulted, raped and then killed. The majority of actual homicides occurred at or in the vicinity of the residence of the victim, with the attacker being known to the deceased. Whilst only 1 of the imagined homicide narratives depicted the use of alcohol by the victim, over half the actual homicides had elevated postmortem blood alcohol levels. These and other disjunctions and convergencies between lay and forensic constructions of violent female death should be viewed in the wider context of enmeshment in social circumstance, and could provide some understanding of how at-risk communities perceive violence against women, thereby providing a foundation for appropriate prevention programmes.