Differences in the kinetics of T cell accumulations in C3H/HeN (Bcg-resistant) and C57BL/6 (Bcg-susceptible) mice infected with Mycobacterium paratuberculosis

The accumulation of various T cell subsets in Bcg-susceptible (C57BL/6) and- resistant (C3H/HeN) strains of mice were compared following an intraperitoneal infection with Mycobacterium paratuberculosis. Groups of mice from both strains were killed at 3, 5, 10, 15, 30, and 150 days after infection and lymphocytes were harvested from the peritoneal exudate cells (PEC), spleen, intestinal epithelial lymphocytes (IEL), lamina propria lymphocytes (LPL), Peyer's patches, and mesenteric lymph node (MLN) and labelled with monoclonal antibodies to CD3, CD4, CD8, gamma delta TCR, CD25, and CD44 for flow cytometric analysis. Uninfected C3H/HeN mice had higher proportions of CD4+ cells in the spleen, MLN, LPL, IEL, and Peyer's patches, while uninfected C57BL/6 mice had higher proportions of CD8+ and/or gamma delta T cells. Significant increases in accumulation of CD8+ and gamma delta T cells were detected in the peritoneum and other tissues in both strains of mice after infection. Higher CD4/CD8 ratios were observed in most lymphoid tissues of C3H/HeN mice, while increased proportions of CD8+ and/or gamma delta T cells were present in C57BL/6 mice. These results indicate that significant differences in T cell profiles exist between these two strains of mice, both inherently and in response to infection with M. paratuberculosis. Innately lower levels of CD4+ cells and/or higher percentages of CD8+ and gamma delta T cells may play a role in the increased suspectibility of C57BL/6 mice to infection with M. paratuberculosis.     

DTS中静止无功补偿器的电磁暂态仿真

介绍了对静止无功补偿器的电磁暂态过程所进行的仿真，并将其嵌入调度员培训仿真器（DTS）中，为保证DTS仿真的精度和速度。采用对静止无功补偿器进行电磁暂态仿真，网络其他部分进行常规机电暂态仿真的综合暂态仿真方法，算例结果证实了静止无功补偿器可以有效地维持线的电压水平提高系统的暂态稳定性。     

Linear regression with delta-modulated integrated signals

An estimate of the accuracy of linear regression is given for instrumentation data where the signal is integrated and DPCM-quantized before processing.     

Demultiplexers for Nanoelectronics Constructed From Nonlinear Tunneling Resistors

When using linear resistors to implement nanoelectronic resistor-logic demultiplexers, codes can be used to improve the voltage margins of these circuits. However, the resistors which have been fabricated in nanoscale crossbars are observed to be nonlinear in their current versus voltage (I-V) characteristics, showing an exponential dependence of current on voltage; we call these devices tunneling resistors. The introduction of nonlinearity can either improve or degrade the voltage margin of a demultiplexer circuit, depending on the particular code used. Therefore, the criterion for choosing codes must be redefined for demultiplexer circuits built from this type of nonlinear resistor. We show that for well-chosen codes, the nonlinearity of the resistors can be advantageous, producing a better voltage margin than can be achieved with linear resistors     

Nerve growth factor receptor TrkA is down-regulated during postnatal development by a subset of dorsal root ganglion neurons

Nerve growth factor (NGF), signaling through its receptor tyrosine kinase, TrkA, is required for the survival of all small and many intermediate-sized murine dorsal root ganglion (DRG) neurons during development, accounting for 80% of the total DRG population. Surprisingly, NGF/TrkA-dependent neurons include a large population that does not express TrkA in adult mice (Silos-Santiago et al., 1995). This finding suggests two hypotheses: Neurons lacking TrkA in the adult may express TrkA during development, or they may be maintained through a paracrine mechanism by TrkA-expressing neurons. To determine whether TrkA is expressed transiently by DRG neurons that lack the receptor in adulthood, we examined the distribution of TrkA protein during development. We show here that TrkA expression is strikingly developmentally regulated. Eighty percent of DRG neurons expressed TrkA during embryogenesis and early postnatal life, whereas only 43% expressed TrkA at postnatal day (P) 21. Because the period of TrkA down-regulation corresponds with a critical period during which nociceptive phenotype can be altered by NGF (see Lewin and Mendell [1993] Trends Neurosci. 16:353-359), we examined whether NGF modulates the down-regulation of TrkA. Surprisingly, neither NGF deprivation nor augmentation altered the extent of TrkA down-regulation. Our results demonstrate a novel form of regulation of neurotrophin receptor expression that occurs late in development. All DRG neurons that require NGF for survival express TrkA during embryogenesis, and many continue to express TrkA during a postnatal period when neuronal phenotype is regulated by NGF. The subsequent down-regulation of TrkA is likely to be importantly related to functional distinctions among nociceptive neurons in maturity.     

Design and synthesis of conformationally-constrained MMP inhibitors

A novel series of conformationally constrained matrix metalloprotease inhibitors was identified. The potencies observed for these inhibitors were highly dependent upon the substitution pattern on the caprolactam ring as well as the succinate moiety.