Inactivation of the Pta-AckA Pathway Causes Cell Death in \u3ci\u3eStaphylococcus aureus\u3c/i\u3e

During growth under conditions of glucose and oxygen excess, Staphylococcus aureus predominantly accumulates acetate in the culture medium, suggesting that the phosphotransacetylase-acetate kinase (Pta-AckA) pathway plays a crucial role in bacterial fitness. Previous studies demonstrated that these conditions also induce the S. aureus CidR regulon involved in the control of cell death. Interestingly, the CidR regulon is comprised of only two operons, both encoding pyruvate catabolic enzymes, suggesting an intimate relationship between pyruvate metabolism and cell death. To examine this relationship, we introduced ackA and pta mutations in S. aureus and tested their effects on bacterial growth, carbon and energy metabolism, cid expression, and cell death. Inactivation of the Pta-AckA pathway showed a drastic inhibitory effect on growth and caused accumulation of dead cells in both pta and ackA mutants. Surprisingly, inactivation of the Pta-AckA pathway did not lead to a decrease in the energy status of bacteria, as the intracellular concentrations of ATP, NAD+, and NADH were higher in the mutants. However, inactivation of this pathway increased the rate of glucose consumption, led to a metabolic block at the pyruvate node, and enhanced carbon flux through both glycolysis and the tricarboxylic acid (TCA) cycle. Intriguingly, disruption of the Pta-AckA pathway also induced the CidR regulon, suggesting that activation of alternative pyruvate catabolic pathways could be an important survival strategy for the mutants. Collectively, the results of this study demonstrate the indispensable role of the Pta-AckA pathway in S. aureus for maintaining energy and metabolic homeostasis during overflow metabolism

The Emergence of Extended Field Technology in the Air Force

The wide-field eddy-current probe was developed to fulfill the inspection requirement of the broach slots in Pratt & Whitney F100-PW-220 Stage-1 and Stage-3 Compressor Disks. The flaw-detection requirement is to inspect an area 0.07 in. from the inner radius of the slot and 0.10 in. from the top and bottom edges for determining the presence of 0.006-and 0.010-in.-deep axially oriented flaws (Figure 1). While the slot is relatively small, the time required for inspection using the previous method is considerable. With this method a D20 (0.029-in.-diameter) split “D” coil is scanned in a “sew-stitch” fashion in the axial direction of the slot. After each scan the probe is indexed one quarter of the coil diameter. A total of 88 scans per slot is required for complete coverage, the time per slot being 20 min; with 40 slots the total inspection time per part is 14 hr when gain-calibration time is taken into account.</p

A dexamethasone prodrug reduces the renal macrophage response and provides enhanced resolution of established murine lupus nephritis

We evaluated the ability of a macromolecular prodrug of dexamethasone (P-Dex) to treat lupus nephritis in (NZB × NZW)F1 mice. We also explored the mechanism underlying the anti-inflammatory effects of this prodrug. P-Dex eliminated albuminuria in most (NZB × NZW)F1 mice. Furthermore, P-Dex reduced the incidence of severe nephritis and extended lifespan in these mice. P-Dex treatment also prevented the development of lupus-associated hypertension and vasculitis. Although P-Dex did not reduce serum levels of anti-dsDNA antibodies or glomerular immune complexes, P-Dex reduced macrophage recruitment to the kidney and attenuated tubulointerstitial injury. In contrast to what was observed with free dexamethasone, P-Dex did not induce any deterioration of bone quality. However, P-Dex did lead to reduced peripheral white blood cell counts and adrenal gland atrophy. These results suggest that P-Dex is more effective and less toxic than free dexamethasone for the treatment of lupus nephritis in (NZB × NZW)F1 mice. Furthermore, the data suggest that P-Dex may treat nephritis by attenuating the renal inflammatory response to immune complexes, leading to decreased immune cell infiltration and diminished renal inflammation and injury

Приклади завдань для позакласної роботи з інформатики у початковій школі

У статті коротко описана методика проведення позакласної роботи з інформатики у початковій школі

A Polymer Membrane Containing Fe0 as a Contaminant Barrier

A polyvinyl alcohol (PVA) membrane containing iron (Fe0) particles was developed and tested as a model barrier for contaminant containment. Carbon tetrachloride, copper (Cu2+), nitrobenzene, 4-nitroacetophenone, and chromate (CrO4 2-) were selected as model contaminants. Compared with a pure PVA membrane, the Fe0/PVA membrane can increase the breakthrough lag time for Cu2+ and carbon tetrachloride by more than 100 fold. The increase in the lag time was smaller for nitrobenzene and 4-nitroacetophenone which stoichiometrically require more iron and for which the PVA membrane has a higher permeability. The effect of Fe0 was even smaller for CrO4 2- because of its slow reaction. Forty-five percent of the iron, based on the content in the dry membrane prior to hydration, was consumed by reaction with Cu2+ and 19% by reaction with carbon tetrachloride. Similarly, 25%, 17%, and 6% of the iron was consumed by nitrobenzene, 4-nitroacetophenone, and CrO4 2-, respectively. These percentages approximately double when the loss of iron during membrane hydration is considered. The permeability of the Fe0/PVA membrane after breakthrough was within a factor of three for that of pure PVA, consistent with theory. These results suggest that polymer membranes with embedded Fe0 have potential as practical contaminant barriers