H4 acetylation, XIST RNA and replication timing are coincident and define x;autosome boundaries in two abnormal X chromosomes

A novel method of estimating enzyme kinetic parameters is presented using the Lambert omega function coupled with nonlinear regression. Explicit expressions for the substrate and product concentrations in the integrated Michaelis-Menten equation were obtained using the omega function which simplified kinetic parameter estimation as root-solving and numerical integration of the Michaelis-Menten equation were avoided. The omega function was highly accurate in describing the substrate and product concentrations in the integrated Michaelis-Menten equation with an accuracy of the order of 10(-16) when double precision arithmetic was used. Progress curve data from five different experimental systems were used to demonstrate the suitability of the omega function for kinetic parameter estimation. In all cases, the kinetic parameters obtained using the omega function were almost identical to those obtained using the conventional root-solving technique. The availability of highly efficient algorithms makes the computation of omega simpler than root-solving or numerical integration. The accuracy and simplicity of the omega function approach make it an attractive alternative for parameter estimation in enzyme kinetics.     

Antigen-pulsed CD8alpha+ dendritic cells generate an immune response after subcutaneous injection without homing to the draining lymph node

Two subsets of murine splenic dendritic cells, derived from distinct precursors, can be distinguished by surface expression of CD8alpha homodimers. The functions of the two subsets remain controversial, although it has been suggested that the lymphoid-derived (CD8alpha+) subset induces tolerance, whereas the myeloid-derived (CD8alpha-) subset has been shown to prime naive T cells and to generate memory responses. To study their capacity to prime or tolerize naive CD4(+) T cells in vivo, purified CD8alpha+ or CD8alpha- dendritic cells were injected subcutaneously into normal mice. In contrast to CD8alpha- dendritic cells, the CD8alpha+ fraction failed to traffic to the draining lymph node and did not generate responses to intravenous peptide. However, after in vitro pulsing with peptide, strong in vivo T cell responses to purified CD8alpha+ dendritic cells could be detected. Such responses may have been initiated via transfer of peptide-major histocompatibility complex complexes to migratory host CD8alpha- dendritic cells after injection. These data suggest that correlation of T helper cell type 1 (Th1) and Th2 priming with injection of CD8alpha+ and CD8alpha- dendritic cells, respectively, may not result from direct T cell activation by lymphoid versus myeloid dendritic cells, but rather from indirect modification of the response to immunogenic CD8alpha- dendritic cells by CD8alpha+ dendritic cells.     

Incremental validity of situational judgment tests.

Using 3 different samples, the authors assessed the incremental validity of situational judgment inventories (SJIs), relative to job knowledge, cognitive ability, job experience, and conscientiousness, in the prediction of job performance. The SJI was a valid predictor in all 3 samples and incrementally so in 2 samples. Relative to the other predictors, SJI's partial correlation with performance, controlling for the other 4 predictors, was superior in most comparisons. Subgroup differences on the SJI also appear to be less than those for cognitive ability and job knowledge, but greater than differences in conscientiousness. The SJI should prove to be a valuable additional measure in the prediction of job performance, but several additional areas of research are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CD95 (Fas/Apo-1) as a receptor governing astrocyte apoptotic or inflammatory responses: a key role in brain inflammation?

Astrocytes are a major cellular component of the brain that are capable of intense proliferation and metabolic activity during diverse inflammatory brain diseases (such as multiple sclerosis, Alzheimer's dementia, tumor, HIV encephalitis, or prion disease). In this biological process, called reactive gliosis, astrocyte apoptosis is frequently observed and could be an important mechanism of regulation. However, the factors responsible for apoptosis in human astrocytes are poorly defined. Here, we report that short term cultured astrocytes derived from different brain regions express significant levels of CD95 at their surface. Only late passage astrocytes are sensitive to CD95 ligation using either CD95 mAb or recombinant CD95 ligand. Blocking experiments using caspase inhibitors with different specificities (DEVD-CHO, z-VAD-fmk, and YVAD-cmk), an enzymatic activity assay, and immunoblotting show that CPP32/caspase-3 play a prominent role in CD95-induced astrocyte death. In contrast, early passage astrocytes are totally resistant to death, but a significant increase in astrocytic IL-8 secretion (p < 0.001, by Wilcoxon's test for paired samples) is observed after CD95 triggering. Production of IL-8 contributes to the resistance of astrocytes to CD95 ligation. Furthermore, in the presence of IFN-gamma, resistant astrocytes became sensitive to CD95-mediated death. These data suggest that microenvironmental factors can influence the consequences of CD95 ligation on astrocytes. Therefore, we propose that CD95 expressed by human astrocytes plays a pivotal role in the regulation of astrocyte life and death and may be a key factor in inflammatory processes in the brain, such as reactive gliosis.     

Pneumoperitoneum does not potentiate the nephrotoxicity of aminoglycosides in rats

OBJECTIVES: Pneumoperitoneum is associated with transient renal dysfunction. To our knowledge, the safety of administering nephrotoxins such as aminoglycosides during pneumoperitoneum has not been studied. Our hypothesis was that pneumoperitoneum potentiates the nephrotoxicity of aminoglycosides. METHODS: From 29 rats we obtained preprocedure 24-hour urine collections. In the pneumoperitoneum group (n = 7), carbon dioxide was insufflated intra-abdominally at 15 mm Hg pressure for 2 hours. In the gentamicin group (n = 7), 10 mg/kg gentamicin was administered intravenously. In the combined pneumoperitoneum/gentamicin group (n = 8), the same dose of gentamicin was administered 10 minutes before pneumoperitoneum. Sham rats (n = 7) received anesthesia only. Urine was collected for the 24 hours after the procedure, and 1 week later blood for creatinine determination and final 24-hour urine collections were obtained. All urine samples were assayed for creatinine and N-acetyl-beta-glucosaminidase (NAG). RESULTS: Only the gentamicin and combined pneumoperitoneum/gentamicin groups presented day 1 values for NAG excretion that were significantly greater than same day sham or paired preprocedure values; the rest of the urinary creatinine and NAG day 1 levels and all the day 7 levels were not significantly different from same day sham or paired preprocedure levels. Day 7 serum creatinine and creatinine clearance did not differ significantly among the groups. CONCLUSIONS: We found that intravenous gentamicin transiently increased urinary excretion of NAG in rats, which resolved within 1 week. Pneumoperitoneum for 2 hours at 15 mm Hg did not increase urinary NAG, either alone or in gentamicin-treated rats. Moreover, our data are sufficient to refute with 95% certainty the possibility that gentamicin plus pneumoperitoneum decreases creatinine clearance more than approximately 60%. These results do not support the hypothesis that pneumoperitoneum potentiates the nephrotoxicity of aminoglycosides.     

Dynamics of macrophage and T cell infection by HIV

In eukaryotes, mitogen-activated protein kinases (MAPKs) are part of signaling modules that transmit diverse stimuli, such as mitogens, developmental cues, or various stresses. Here, we report a novel alfalfa MAPK, Medicago MAP kinase 3 (MMK3). Using an MMK3-specific antibody, we detected the MMK3 protein and its associated activity only in dividing cells. The MMK3 protein could be found during all stages of the cell cycle, but its protein kinase activity was transient in mitosis and correlated with the timing of phragmoplast formation. Depolymerization of microtubules by short treatments with the drug amiprophosmethyl during anaphase and telophase abolished MMK3 activity, indicating that intact microtubules are required for MMK3 activation. During anaphase, MMK3 was found to be concentrated in between the segregating chromosomes; later, it localized at the midplane of cell division in the phragmoplast. As the phragmoplast microtubules were redistributed from the center to the periphery during telophase, MMK3 still localized to the whole plane of division; thus, phragmoplast microtubules are not required to keep MMK3 at this location. Together, these data strongly support a role for MMK3 in the regulation of plant cytokinesis.     

Estimates of cross-validity for stepwise regression and with predictor selection.

The effects of preselection of predictors (e.g., stepwise regression) on formula estimates of cross-validity were examined. Three actual data sets were used to generate populations of varying sample size, population validity, and number of predictors. No formula estimate provided an unbiased estimate of the population cross-validity, although some formula estimates were less biased than others. More important, having an adequate sample size (relative to number of predictors) was the issue most affecting the utility of the formula estimates. Another conclusion was that adjusted R2 provided by at least some popular software programs can provide gross overestimates of cross-validity and should not be used as such. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of the occurrence of Listeria species in raw sheep milk

The occurrence of bacteria from the genus Listeria in raw sheep milk and traditional local cheese was studied in three regions of the Karak district of Jordan. Conventional plating methods for the detection of Listeria species were followed to determine the average and the percentage of the contaminated samples. The result shows that there were significant differences between the regions in the study concerning the average and the percentage of positive occurrences of Listeria species in raw sheep milk. The results also showed that mainly L. monocytogenes and, to a lesser degree, L. ivanovii and L. innocua were found in the milk samples, while the occurrence of L. monocytogenes in cheese samples was very low.