Puerperal infections

This case report focuses on the communication difficulties of a 21-year-old medical student with severe-to-profound sensorineural hearing loss. The greatest difficulties reported by the patient were for stethoscope use and slide presentations in darkened rooms. Successful audiologic management was accomplished for this patient via use of a behind-the-ear (BTE) FM system for classroom use and a "homemade" amplified stethoscope that enabled him to hear diagnostic heart sounds for clinical use. The amplified stethoscope provided greater low-frequency gain for this patient than was available through other commercial units.     

Blockade of tetrahydrobiopterin synthesis protects neurons after transient forebrain ischemia in rat: a novel role for the cofactor

The generation of nitric oxide (NO) aggravates neuronal injury. (6R)-5,6,7,8-Tetrahydro-L-biopterin (BH4) is an essential cofactor in the synthesis of NO by nitric oxide synthase (NOS). We attempted to attenuate neuron degeneration by blocking the synthesis of the cofactor BH4 using N-acetyl-3-O-methyldopamine (NAMDA). In vitro data demonstrate that NAMDA inhibited GTP cyclohydrolase I, the rate-limiting enzyme for BH4 biosynthesis, and reduced nitrite accumulation, an oxidative metabolite of NO, without directly inhibiting NOS activity. Animals exposed to transient forebrain ischemia and treated with NAMDA demonstrated marked reductions in ischemia-induced BH4 levels, NADPH-diaphorase activity, and caspase-3 gene expression in the CA1 hippocampus. Moreover, delayed neuronal injury in the CA1 hippocampal region was significantly attenuated by NAMDA. For the first time, these data demonstrate that a cofactor, BH4, plays a significant role in the generation of ischemic neuronal death, and that blockade of BH4 biosynthesis may provide novel strategies for neuroprotection.     

关于那些古董玩意儿

最近和几个朋友相约去吃饭,席间,电话铃响起,其中一个朋友从包里不慌不忙地拿出一个体积庞大、黑糊糊的玩意儿开始通话,定睛一看,居然是匿迹江湖多年的大哥大。这让我有点不理解,平时就喜欢烧数码产品的朋友怎么今天用起这种古董来了?朋友说是为了装酷,这让我想起了和大哥大几乎同时代的BP机。最近看到一则新闻,在通讯技术发展比中国更快的美国,BP机仍然是一项挣钱的买卖:纳斯达克市场上甚至还有专门的寻呼企业,如USAMobilitylnc(USMO),其业绩斐然,股价也稳定在20美元上下,远胜过一些高技术企业。     

Accuracy of forest mapping based on Landsat TM data and a kNN-based method

A multi-source forest inventory (MSFI) method has been developed for use in the Norwegian National Forest Inventory (NFI). The method is based on a k-nearest neighbour rule and uses field plots from the NFI, land cover maps, and satellite image data from Landsat Thematic Mapper. The inventory method is used to produce maps of selected forest variables and to estimate the selected forest variables for large areas such as municipalities. In this study, focus has been on the qualitative variables ‘dominating species group’ and ‘development class’ because these variables are of central interest to forest managers. A mid-summer Landsat 5 TM scene was used as image data, and all NFI plots inside the scene were used as a reference dataset. The relationship between the spectral bands and the forest variables was analysed, and it was found that the levels of association were low. A leave-one-out method based on the reference dataset was used to estimate the pixel-level accuracies. They were found to be relatively low with 63% agreement for species groups. An independent control survey was available for a municipality and estimates from the MSFI were compared to it. The levels of error were quite high. It was concluded that the large area estimates were biased by the reference dataset.     

Testosterone and depression in aging men

In men, testosterone secretion affects neurobehavioral functions such as sexual arousal, aggression, emotional tone, and cognition. Beginning at approximately age 50, men secrete progressively lower amounts of testosterone; about 20% of men over age 60 have lower-than-normal levels. The psychiatric sequelae are poorly understood, yet there is evidence of an association with depressive symptoms. The authors reviewed 1) the physiology of the hypothalamic-pituitary-gonadal axis and its changes with age in men; and 2) the evidence linking testosterone level and major depression in men. Data on this relationship are derived from two types of studies: observational studies comparing testosterone levels and secretory patterns in depressed and non-depressed men, and treatment studies using exogenous androgens for male depression. The data suggest that some depressed older men may have state-dependent low testosterone levels and that some depressed men may improve with androgen treatment.     

The paternal effect gene ms(3)sneaky is required for sperm activation and the initiation of embryogenesis in Drosophila melanogaster

Calcium sensor proteins translate transient increases in intracellular calcium levels into metabolic or mechanical responses, by undergoing dramatic conformational changes upon Ca2+ binding. A detailed analysis of the calcium binding-induced conformational changes in the representative calcium sensors calmodulin (CaM) and troponin C was performed to obtain insights into the underlying molecular basis for their response to the binding of calcium. Distance difference matrices, analysis of interresidue contacts, comparisons of interhelical angles, and inspection of structures using molecular graphics were used to make unbiased comparisons of the various structures. The calcium-induced conformational changes in these proteins are dominated by reorganization of the packing of the four helices within each domain. Comparison of the closed and open conformations confirms that calcium binding causes opening within each of the EF-hands. A secondary analysis of the conformation of the C-terminal domain of CaM (CaM-C) clearly shows that CaM-C occupies a closed conformation in the absence of calcium that is distinct from the semi-open conformation observed in the C-terminal EF-hand domains of myosin light chains. These studies provide insight into the structural basis for these changes and into the differential response to calcium binding of various members of the EF-hand calcium-binding protein family. Factors contributing to the stability of the Ca2+-loaded open conformation are discussed, including a new hypothesis that critical hydrophobic interactions stabilize the open conformation in Ca2+ sensors, but are absent in "non-sensor" proteins that remain closed upon Ca2+ binding. A role for methionine residues in stabilizing the open conformation is also proposed.     

Reduced mechanical efficiency in chronic obstructive pulmonary disease but normal peak VO2 with small muscle mass exercise

We studied six patients with chronic obstructive pulmonary disease (COPD) (FEV1 = 1.1 +/- 0.2 L, 32% of predicted) and six age- and activity level-matched control subjects while performing both maximal bicycle exercise and single leg knee-extensor exercise. Arterial and femoral venous blood sampling, thermodilution blood flow measurements, and needle biopsies allowed the assessment of muscle oxygen supply, utilization, and structure. Maximal work rates and single leg VO2max (control subjects = 0.63 +/- 0.1; patients with COPD = 0.37 +/- 0.1 L/minute) were significantly greater in the control group during bicycle exercise. During knee-extensor exercise this difference in VO2max disappeared, whereas maximal work capacity was reduced (flywheel resistance: control subjects = 923 +/- 198; patients with COPD = 612 +/- 81 g) revealing a significantly reduced mechanical efficiency (work per unit oxygen consumed) with COPD. The patients had an elevated number of less efficient type II muscle fibers, whereas muscle fiber cross-sectional areas, capillarity, and mitochondrial volume density were not different between the groups. Therefore, although metabolic capacity per se is unchanged, fiber type differences associated with COPD may account for the reduced muscular mechanical efficiency that becomes clearly apparent during knee-extensor exercise, when muscle function is no longer overshadowed by the decrement in lung function.     

Forecasting bed needs and recommending facilities plans for community hospitals: a review of past performance

A university-based hospital consulting group reviewed six studies of Michigan hospitals retrospectively in 1975. The studies represented all those done between 1967 and 1971 requiring forecasts of acute bed supply and service needs. The original studies developed forecasts using empirical studies of patient origin and rigorously prepared authoritative forecasts of county populations. The 1975 review compared forecasts of population, service population, and bed need against current values and also interviewed clients to assess retrospective satisfaction with the recommendations. Although the consultants strove steadily to minimize the bed supply and base population forecasts were accurate, the studies overestimated bed needs. Further, the clients were often dissatisfied with the original recommendations, and frequently acted to exceed them. Comparing the 1975 actual with what would now be recommended by the consultant indicates that the "error" cost the communities about $50 per person per year.     

表面微观形貌的显微干涉检测原理及干涉显微镜发展现状

追踪分析世界上表面微观形貌检测方面显微干涉检测原理的最新进展 ,比较干涉显微镜用于检测表面微观形貌时具有的形式、结构特点 ,分析选型研制干涉显微镜可能遇到的问题及应该研究的方面。     

LiNbO3集成光学元件在光纤传感器中的应用

Li Nb O3 集成光学元件在光纤传感器中占有重要地位。叙述了 Li Nb O3 集成光学元件在光纤传感器中的应用情况及最新发展 ,为光纤传感器深入研究提供了有益参考