Regulation of D-alanine carboxypeptidase and peptidoglycan cross-linkage in amino acid-deprived Escherichia coli

The effect of amino acid deprivation on the activities of D-alanine carboxypeptidase (CPase) and peptidoglycan transpeptidase in Escherichia coli was determined. Enzymes were assayed in ether-treated bacteria (ETB) which were permeable to peptidoglycan nucleotide precursors. ETB were prepared at intervals from cultures grown in the presence and absence of a required amino acid. The specific activity of CPase in ETB decreased 50 to 85% during amino acid deprivation. This was paralleled by a 60 to 70% decrease in the specific activity of peptidoglycan transpeptidase. Both enzymes reached their lowest level of activity about 40 min after the onset of amino acid deprivation. The decrease in CPase activity apparently was not due to degradation of the enzyme, since full activity was restored after disruption of ETB by sonication. A decrease in CPase activity was associated with an enhancement of transpeptidation. The peptidoglycan synthesized in vitro by amino acid-deprived ETB was 1.7 times more cross-linked than the peptidoglycan synthesized by control ETB These results support the proposal that CPase may be involved in regulating transpeptidation in E. coli.     

A simple method for testing the effects of reagents on the mechanical properties of sheets of connective tissues

A simple and rapid method of testing the effects of reagents on a mechanical property of skin or other sheets of connective tissue, by measurements of the force required to punch a hole or drive a conical probe through the tissue, is described. The reagents tested (cysteamine, hydrogen ion concentration, cyanide) had essentially the same effects as in simple tensile tests.     

Inactivation of respiratory syncytial virus by detergents and disinfectants

The activity of a number of detergents and disinfectants against respiratory syncytial virus (RSV) was evaluated in an in vitro assay system. Equal volumes of RSV and serial 10-fold dilutions of the test agents were mixed at 4 degrees C for 5 minutes. The RSV titer in each mixture was compared with that of untreated RSV alone. In 14 experiments with input RSV titers ranging from 2.6 x 10(3) to 2 x 10(7) plaque-forming units/ml, a 10-fold dilution of 5.25% sodium hypochlorite (generic bleach) inactivated (> or = 3-log reduction in titer) the virus. With lower RSV titers inactivation was also observed at a 100-fold dilution of bleach. Fetal calf serum concentrations up to 50% as an organic load did not diminish the bleach effect. The degree of RSV inactivation was also defined for Lysol, povidone-iodine, Amphyl, Hibiclens, Osyl, ethanol and Listermint. The short contact time, the reproducible nature of the findings and the continued effectiveness with increasing organic loads all suggest that detergents and disinfectants can potentially play an important role in decreasing the spread of RSV infection.     

Chromatin assembly in a yeast whole-cell extract

A simple in vitro system that supports chromatin assembly was developed for Saccharomyces cerevisiae. The assembly reaction is ATP-dependent, uses soluble histones and assembly factors, and generates physiologically spaced nucleosomes. We analyze the pathway of histone recruitment into nucleosomes, using this system in combination with genetic methods for the manipulation of yeast. This analysis supports the model of sequential recruitment of H3/H4 tetramers and H2A/H2B dimers into nucleosomes. Using a similar approach, we show that DNA ligase I can play an important role in template repair during assembly. These studies demonstrate the utility of this system for the combined biochemical and genetic analysis of chromatin assembly in yeast.     

Postimaging brain distortion: magnitude, correlates, and impact on neuronavigation

OBJECT: This prospective study was conducted to quantify brain shifts during open cranial surgery, to determine correlations between these shifts and image characteristics, and to assess the impact of postimaging brain distortion on neuronavigation. METHODS: During 48 operations, movements of the cortex on opening, the deep tumor margin, and the cortex at completion were measured relative to the preoperative image position with the aid of an image-guidance system. Bone surface offset was used to assess system accuracy and correct for registration errors. Preoperative images were examined for the presence of edema and to determine tumor volume, midline shift, and depth of the lesion below the skin surface. Results were analyzed for all cases together and separately for four tumor groups: 13 meningiomas, 18 gliomas, 11 nonglial intraaxial lesions, and six skull base lesions. For all 48 cases the mean shift of the cortex after dural opening was 4.6 mm, shift of the deep tumor margin was 5.1 mm, and shift of the cortex at completion was 6.7 mm. Each tumor group displayed unique patterns of shift, with significantly greater shift at depth in meningiomas than gliomas (p = 0.007) and significantly less shift in skull base cases than other groups (p = 0.003). Whereas the preoperative image characteristics correlating with shift of the cortex on opening were the presence of edema and depth of the tumor below skin surface, predictors of shift at depth were the presence of edema, the lesion volume, midline shift, and magnitude of shift of the cortex on opening. CONCLUSIONS: This study quantified intraoperative brain distortion, determined the different behavior of tumors in four pathological groups, and identified preoperative predictors of shift with which the reliability of neuronavigation may be estimated.     

A compressional wave seismic model for the Ashrafi-1 well

Despite disappointing drilling results, the South Caspian basin has yielded scientific results of significant value to future exploration. This paper describes work that utilized data from the offshore Ashrafi-1 well, but we believe it has applications to exploration elsewhere in Azerbaijan. The North Absheron Operating Company (NAOC) drilled the Ashrafi-1 well between November 30, 1997 and February 6, 1998 to a total depth of 3668 m (sub Caspian sea level). The Balakhany and Pereryva Suite (SP) Formations were wet but the Upper Kirmaku Sandy (NKP) Formation tested oil and the Lower Kirmaku (PK) Formation tested gas, both at high flow rates. Anomalously high stack amplitude responses, generally conforming to structural closure, had been observed in the 3D seismic data at the NKP and PK Formations prior to drilling of the well. An offset synthetic modeling study was undertaken, post-drill, to determine the in-situ amplitude response (stack and amplitude variation with offset, or AVO) for both pay and wet zones and to model the changes in AVO and stacked amplitudes in response to changes in variables such as thickness, fluid fill and porosity. As well as the 3D seismic data set, the principal data sources used were a dipole sonic log for compressional wave velocity (Vp) and shear wave velocity (Vs); checkshots for time-to depth (T–D) conversion; a density log; log interpretations of porosity; fluid properties based on pressure–volume–temperature (PVT) analysis of fluids from drill stem tests (DSTs) and pressure/temperature data. In this simple case, despite the highly permeable reservoir rocks, the Gassmann assumption of immobile fluids within the pore space was used. Although the effects of partial gas saturation are known to be a problem elsewhere in this basin, density modeling derived from borehole-guided long offset AVO was not attempted. Despite this, normal incident amplitudes, derived from pre-stack data, cross-plotted against amplitude gradients suggest a methodology for distinguishing wet sandstones from gas and oil in this basin in the absence of recent leakage. Despite the difference in response for oil and gas (oil gave a stronger response than gas), a statistically meaningful number of wells is not yet available and this result may be influenced by local lithologic effects. Thus, the ability to distinguish oil from gas ahead of the drill bit — which is of vital importance in evaluating commerciality — is not proven.     

Review of Adapting cognitive therapy for depression.

Reviews the book, Adapting cognitive therapy for depression by Mark A. Whisman (see record 2008-03297-000). The goal of this volume is to provide detailed, empirically supported instructions for adapting CT for complex, comorbid presentations in depression. All of the chapters follow a similar format, which makes them very easy to read and absorb. They are all written by experts in the field using clear, jargon-free language. Each chapter provides instructions for adapting the assessment, case conceptualization, and cognitive treatment of clients presenting with a number of types of complexity. For the most part, these instructions are supported by the research literature. As such, this is a work that is readily accessible to professionals at all levels of training and expertise, and represents an invaluable resource for clinicians working with depressed clients. Furthermore, this text is an excellent scholarly resource of the most up-to-date research literature on the applicability of CT to complex populations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)