用16～100V电源提供12V及3A输出的宽范围稳压器

同步降压稳压器具有高效率，广泛用于输入电压为12V或12V以下的设备中。但随着输入电压接近100V，宽范围稳压器设计变得越来越困难，合适IC的选择范围亦变得相当窄。本设计实例将用于回扫稳压器电路的电流模式PWMIC与100V的栅极驱动器IC相结合，产生可在高达100V输入电压下工作的高性能同步降压稳压器。     

Bone loss after hip fracture is correlated to the postoperative degree of mobilisation

This study quantifies changes in bone mineral density (BMD) in the opposite hip and in both proximal tibiae and the correlation with the use of walking aids for patients with two types of hip fracture during the 1st year after surgery. In all, 26 women and 15 men aged 42-88 years (median 71 years) were included. Twenty-one patients had an intracapsular hip fracture (ICF) and 20 had an intertrochanteric fracture (ITF). All patients were treated with a dynamic hip screw. BMD was measured by dual X-ray absorptiometry (DXA; LUNAR, Wisconsin) within the 1st week after surgery and after 3, 6 and 12 months. Initial BMD of the non-fractured hip was significantly lower for both fracture groups compared with reference material. For both fracture types there was a significant decrease in BMD of the non-fractured hip and proximal tibia of the fractured leg during the first 3 months, which still persisted a year after surgery. Improved mobilisation between two examinations was positively correlated with changes in BMD of the proximal tibia of the fractured leg and the non-fractured hip.     

Effect of specific training on menstruation and bone strength]

Secondary amenorrhoea is found with increased incidence in female athletes performing hard endurance training, especially when combined with demands for a low body weight. The etiology is multifactorial, but the energy balance (energy intake) in relation to the amount and intensity of training probably plays a crucial role. Long-lasting amenorrhoea may reduce the bone mineral content, perhaps partly irreversibly, especially in the lumbar vertebrae in long-distance runners. In gymnasts and light-weight rowers with a similarly high incidence of amenorrhoea, a much less pronounced effect on the lumbar bone mineral content has been reported in a few, small studies, pointing to a possible positive influence of specific training. The finding of stress fractures in an amenorrhoeic athlete should lead to further evaluation of the bone mineral status.     

Synaptic organisation of neuropeptide-containing preganglionic boutons in lumbar sympathetic ganglia of guinea pigs

Within the lumbar sympathetic ganglia of guinea pigs, the endings of different populations of neuropeptide-containing preganglionic neurons form well-defined pericellular baskets of boutons around target neurons in specific functional pathways. We have used multiple-labelling immunofluorescence, confocal microscopy, and ultrastructural immunocytochemistry to investigate synaptic organisation within pericellular baskets labelled for immunoreactivity to calcitonin gene-related peptide (CGRP), substance P (SP), or the pro-enkephalin-derived peptide, met-enkephalin-arg-gly-leu (MERGL) in relation to their target neurons. Different functional populations of neurons, identified by their neurochemical profile, showed a significant degree of spatial clustering and predicted well the distribution of specific classes of pericellular baskets. Most of the boutons in a basket were completely surrounded by Schwann cell processes and did not form synapses. The synapses that were present were made mostly onto dendrites enclosed by the Schwann cell sheath surrounding the neuron within the basket. These dendrites probably originated from neurochemically similar neighbouring neurons. Nevertheless, some of the boutons in the baskets did form synapses with the cell body or proximal dendrites of the neuron they surrounded. Occasionally, cell bodies received a relatively high number of synapses and close appositions from boutons in a pericellular basket. Synaptic convergence of two immunohistochemically distinct types of preganglionic inputs was found in baskets of SP-immunoreactive or MERGL-immunoreactive, but not CGRP-immunoreactive, boutons. Taken together, our results show that the appearance of pericellular baskets is primarily due to the packing of the target neurons. The grouping of functionally similar classes of neurons with their pathway-specific projections of peptide-containing preganglionic neurons suggests that peptides could exert their effects in relatively well-defined zones within the ganglia.     

An alternate pathway for T cell development supported by the bone marrow microenvironment: recapitulation of thymic maturation

In the principal pathway of alpha/beta T cell maturation, T cell precursors from the bone marrow migrate to the thymus and proceed through several well-characterized developmental stages into mature CD4+ and CD8+ T cells. This study demonstrates an alternative pathway in which the bone marrow microenvironment also supports the differentiation of T cell precursors into CD4+ and CD8+ T cells. The marrow pathway recapitulates developmental stages of thymic maturation including a CD4+CD8+ intermediary cell and positive and negative selection, and is strongly inhibited by the presence of mature T cells. The contribution of the marrow pathway in vivo requires further study in mice with normal and deficient thymic or immune function.     

Oral glucocorticosteroid-sparing effect of budesonide administered by Turbuhaler: a double-blind, placebo-controlled study in adults with moderate-to-severe chronic asthma. Pulmicort Turbuhaler Study Group

The purpose of this study was to evaluate the correlation between alteration in telomere length and prognosis in patients with pathological stage I-II non-small cell lung cancer. We measured telomeric repeat length and telomerase activity by use of southern blot analysis of terminal restriction fragments and a non-radioactive ELISA-based assay, respectively. RESULTS: Alterations in TRF lengths were present in 17(29.8%) of 57 patients. Patients with altered TRF length had significantly shorter survival than did patients without (P = 0.0051). In multivariate analysis, only alteration in TRF length independently correlated with shortened survival (P = 0.0033).     

Association of beta-agonists with corresponding beta 2- and beta 1-adrenergic pentapeptide sequences

Synthesized beta 1- and beta 2-pentapeptide sequences corresponding to published adrenoceptor transmembrane activation site subtypes were investigated in vitro for selectivity in association for drug ligands of known selectivity. Both nuclear magnetic resonance spectroscopy and molecular mechanics demonstrated that structural differences among the corresponding pentapeptide activation-site sequences can explain agonist selectivity. Results suggest the agonists bind across the activation site loop on the second transmembrane alpha-helix by dipole/dipole interactions between a ligand and the peptide. Since electrostatic interactions within the membrane may determine the rate of intercellular ion flux, agonist association across the activation site sequence could thereby decrease electrostatic resistance to positive ion flux into the cell. Interactions between the peptides and the ligands may provide insight into the structures and mechanisms involved in association of ligands for the identical sequences on the beta-adrenoreceptors.     

Collagen gene expression in the neomatrix of carcinoma of the breast

Excessive deposition of extracellular matrix or neomatrix is a characteristic of desmoplastic invasive breast carcinomas. Type I and III collagens are abundant neomatrix components. Archival breast tissue sections were studied using 35S-labeled cDNA probes for alpha 1(I) and alpha 1(III) procollagen and in situ hybridization. Among the 33 invasive breast cancers, hybridization was seen forming a gradient-like pattern in fibroblasts closest to tumor cells. In the 10 ductal carcinomas in situ studied, a ring-like pattern of hybridization was seen in proximity to the basement membrane zone. Adjacent normal and benign tissues did not demonstrate the patterns of hybridization described in malignant tissues. Gene expression for neomatrix interstitial collagens occurs before there is evidence of invasion in carcinoma of the breast.