The stationary-phase-exit defect of cydC (surB) mutants is due to the lack of a functional terminal cytochrome oxidase

The surB gene was identified as a gene product required for Escherichia coli cells to exit stationary phase at 37 degrees C under aerobic conditions. surB was shown to be the same as cydC, whose product is required for the proper assembly and activity of cytochrome d oxidase. Cytochrome d oxidase, encoded by the cydAB operon, is one of two alternate terminal cytochrome oxidases that function during aerobic electron transport in E. coli. Mutations inactivating the cydAB operon also cause a temperature-sensitive defect in exiting stationary phase, but the phenotype is not as severe as it is for surB mutants. In this study, we examined the phenotypes of surB1 delta(cydAB) double mutants and the ability of overexpression of cytochrome o oxidase to suppress the temperature-sensitive stationary-phase-exit defect of surB1 and delta(cydAB) mutants and analyzed spontaneous suppressors of surB1. Our results indicate that the severe temperature-sensitive defect in exiting stationary phase of surB1 mutants is due both to the absence of terminal cytochrome oxidase activity and to the presence of a defective cytochrome d oxidase. Membrane vesicles prepared from wild-type, surB1, and delta(cydAB) strains produced superoxide radicals at the same rate in vitro. Therefore, the aerobic growth defects of the surB1 and delta(cydAB) strains are not due to enhanced superoxide production resulting from the block in aerobic electron transport.     

Frequent clones of p53-mutated keratinocytes in normal human skin

The multiple genetic hit model of cancer predicts that normal individuals should have stable populations of cancer-prone, but noncancerous, mutant cells awaiting further genetic hits. We report that whole-mount preparations of human skin contain clonal patches of p53-mutated keratinocytes, arising from the dermal-epidermal junction and from hair follicles. These clones, 60-3000 cells in size, are present at frequencies exceeding 40 cells per cm2 and together involve as much as 4% of the epidermis. In sun-exposed skin, clones are both more frequent and larger than in sun-shielded skin. We conclude that, in addition to being a tumorigenic mutagen, sunlight acts as a tumor promoter by favoring the clonal expansion of p53-mutated cells. These combined actions of sunlight result in normal individuals carrying a substantial burden of keratinocytes predisposed to cancer.     

Consumption of reduced-fat products: effects on parameters of anti-oxidative capacity

Plasma levels of fibrinogen, factor VIIc and prothrombin fragment F1 + 2, a marker of thrombin generation in vivo, were studied in 68 subjects with serum total cholesterol (TC) levels between 135 and 349 mg/dl but without clinical evidence of cardiovascular disease and other atherosclerotic risk factors. F1 + 2 plasma levels were directly correlated with TC (p < 0.0004), low-density lipoprotein cholesterol (LDL-C; p < 0.0018) and factor VIIc (p < 0.024). Thirty-five subjects with TC greater than 249 mg/dl (median value of the whole group) showed higher levels of F1 + 2 (p < 0.0001) and fibrinogen (p < 0.0015) than those with TC lower than 249 mg/dl. In subjects with TC > 249 mg/dl and F1 + 2 > 1.2 nM (median value of the whole group), a cholesterol-lowering drug (simvastatin) was able to reduce F1 + 2 (p < 0.009) as well as TC and LDL-C. This study shows a relationship between serum cholesterol and the rate of thrombin generation supporting the hypothesis that a hypercoagulable state may occur in hypercholesterolemic subjects before the onset of clinical evidence of atherosclerotic cardiovascular disease.     

Study of the beta -delayed neutron decay of 18N

The shortage of suitable liver donors for children has motivated the use of ABO-incompatible (ABO-I) grafts for transplantation in urgent situations. However, survival after ABO-I liver grafts has been reported at about 30% as compared with 80% in cases of ABO-identical or -compatible liver grafts. This difference has been attributed to antibody-mediated, hyperacute or chronic liver rejection, due to preformed ABO antibodies (alloantibodies). In this study, we report our results with ABO-I livers in children without alloantibodies at the time of transplantation. From January 1988 to June 1993, 143 OLT were performed in 122 children. Eight children received 8 ABO-I liver grafts. Of these, 7 patients were included in the study. All 7 were alloantibody free before OLT. Five children were spontaneously alloantibody free, while in 2 children, the plasma alloantibodies were eliminated before and after transplantation using intravenous infusion of specific blood group antigens of the donor blood group (soluble antigens). Immunosuppression consisted of a triple-drug treatment combining CsA, AZA, and steroids. The follow-up period was between 10 and 48 months. One child died from a surgical complication. Six children survived, but 1 died 10 months later from intestinal obstruction. There were no graft losses and no episodes of hyperacute or chronic rejection. The graft and patient survival rate was 71%. There was a 28% incidence of rejection, but all were mild (requiring steroid boluses only). Our results suggest that the absence of ABO alloantibodies at the time of and after transplantation can protect ABO-I liver grafts against antibody-mediated rejection, whether hyperacute or chronic, and that soluble antigens are effective in eliminating alloantibodies in children.     

Interobserver variation in the assessment of the sampling quality of cervical smears

The present study was carried out to investigate the biochemical and morphological changes in the liver after ligation of the hepatic artery (HA) in the presence and in the absence of extrahepatic cholestasis (EHC). The study was conducted on 100 rats divided into four groups of 25 animals each: group 1, sham operation; group 2, hepatic artery ligation (HAL); group 3, bile duct ligation (BDL); and group 4, HAL plus BDL. All animals were sacrificed 7 days after surgery when total bilirubin and fractions, alkaline phosphatase (AP), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) were measured in serum and on the inner hepatocyte mitochondrial membrane (IHMM); the incidence of necrosis and the volume fractions of vessels, bile ducts and hepatocytes in the liver were also determined. HAL reduces the relative volumes of bile ducts, with no changes in levels of bilirubin and fractions, AP, ALT, AST and IHMM, but HAL associated with EHC reduces duct proliferation and the liver becomes more vulnerable to necrosis. In conclusion, the normal liver depends on HA flow and this dependence is more evident in the presence of EHC.     

Fenoldopam improves renal hemodynamics impaired by positive end-expiratory pressure

BACKGROUND: Mechanical ventilation with positive end-expiratory pressure (PEEP) can impair renal hemodynamics. Fenoldopam, a dopamine receptor agonist, has been shown, in animal experiments, to improve renal perfusion. The purpose of the current study was to examine the effects of this agent on altered renal hemodynamics secondary to positive pressure ventilation. METHODS: Twelve patients requiring mechanical ventilation of their lungs and PEEP for the treatment of hypoxemia after multiple trauma or visceral surgery were studied. Hemodynamic variables, renal vascular resistance, urine flow, creatinine, inulin and PAH clearance, and excretion of sodium and potassium (NaE and KE) were measured before and after introduction of a level of PEEP high enough to decrease urine flow rate by 25% or more, and after administration of intravenous fenoldopam. RESULTS: No hemodynamic effect resulted from 0.1 microgram.kg-1.min-1, but 0.2 micrograms.kg-1.min-1 fenoldopam decreased both diastolic and mean arterial blood pressure from 66 +/- 37 (mean +/- SEM) to 57 +/- 21 mmHg, and from 83 +/- 3 to 74 +/- 4 mmHg, respectively. Renal vascular resistance was reduced from 54 +/- 12 to 19 +/- 5 dynes.s.cm-5 at 0.2 micrograms.kg-1.min-1. Fenoldopam produced a dose-related increase in renal blood flow and PAH clearance. With 0.2 micrograms.kg-1.min-1 fenoldopam, urine flow increased from 81 +/- 25 to 116 +/- 29 ml/h, NaE from 28 +/- 7 to 85 +/- 70 microM/min, and KE from 65 +/- 12 to 109 +/- 16 microM/min. CONCLUSIONS: The results of the current study indicate that intravenous fenoldopam at a dose of 0.2 micrograms.kg-1.min-1 improves renal hemodynamics and increases Na and K excretion in patients requiring mechanical ventilation of their lungs and PEEP. These effects are probably caused by an increased kidney perfusion secondary to renal artery vasodilation.     

Understanding of the concept of numerically "less" by bottlenose dolphins (Tursiops truncatus).

In 2 experiments, bottlenose dolphins (Tursiops truncatus) judged the ordinal relationship between novel numerosities. The dolphins were first trained to choose the exemplar with the fewer number of items when presented with just a few specific comparisons (e.g., 2 vs. 6, 1 vs. 3, and 3 vs. 7). Generalization of this rule was then tested by presenting the dolphins with all possible pairwise comparisons between 1 and 8. The dolphins chose the exemplar with the fewer number of items at levels far above chance, showing that they could recognize and represent numerosities on an ordinal scale. Their pattern of errors was consistent with the idea of an underlying analog magnitude representation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reactive Power Compensation Technologies: State-of-the-Art Review

This paper presents an overview of the state of the art in reactive power compensation technologies. The principles of operation, design characteristics and application examples of Var compensators implemented with thyristors and self-commutated converters are presented. Static Var generators are used to improve voltage regulation, stability, and power factor in ac transmission and distribution systems. Examples obtained from relevant applications describing the use of reactive power compensators implemented with new static Var technologies are also described.     

Processing and microstructural evolution of powder metallurgy Zn-22 Pct Al eutectoid alloy containing nanoscale dispersion particles

The present article deals with the processing and microstructural evolution of powder metallurgy (PM) Zn-22Al pct eutectoid alloy. The powder material was produced through inert gas atomization and then cryomilled in liquid nitrogen. The milled powder particles were consolidated by hot isostatic pressing (“hipping”) followed by thermomechanical treatment, resulting in a two-phase microstructure. The microstructures were characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The principal processing factors and microstructural characteristics associated with the major processing steps, including spray atomization, mechanical milling (MM), consolidation, and heat treatment, were evaluated and discussed. Hot isostatic pressing and extrusion followed by heat treatment to produce the superplastic structure (Al-rich phase and Zn-rich phase) are effective in elimination porosity. A TEM examination of the microstructure of the alloy after processing reveals the presence of nanodispersion particles that are not uniformly distributed. The formation of the dispersions was attributed to the interaction between the powder material (primarily Al phase) and environmental elements such as oxygen and nitrogen during milling. Moreover, the size and distribution of the dispersions present in the bulk material met the anticipated requirements for serving as inhibitors for grain growth and barriers for dislocation movement. The TEM observations on crept specimens reveal extensive dislocation/dispersion interactions.