Self-heating of submicrometer InP-InGaAs DHBTs

We studied the thermal properties of submicron InP-InGaAs-InP double heterojunction bipolar transistors (DHBTs) with emitter dimensions of A = 0.25 /spl times/ 4 /spl mu/m/sup 2/. From the temperature dependence of V/sub bc/, we measured a thermal resistance of R/sub th/ = 3.3 /spl deg/C/mW for DHBTs with ion-implanted n+-InP subcollector at room temperature, compared to a high R/sub th/ = 7.5 /spl deg/C/mW from DHBTs with conventional grown InGaAs subcollector. Two-dimensional device simulations confirm the measured results.     

On stage single cell identification of rat spermatogenic cells

We investigated the early effects of the anti-idiotypic antibody (clone 1D5), which recognized the estrogen receptor (ER), on cytosolic free calcium concentration ([Ca2+]i) and its long term effects on creatine kinase (CK) specific activity in female human and rat osteoblasts. These actions were compared to the known membrane and genomic effects of 17 beta estradiol (E2). Like E2, clone 1D5 increased within 5 s [Ca2+]i in both cell types by two mechanisms: 1) Ca2+ influx through voltage-gated Ca2+ channels as shown by using EGTA a chelator of extracellular Ca2+, and nifedipine, a Ca2+ channel blocker; 2) Ca2+ mobilization from the endoplasmic reticulum as shown by using phospholipase C inhibitors, such as neomycin and U-73122, which involved a Pertussis toxin-sensitive G-protein. Clone 1D5 and E2 stimulated CK specific activity in human and rat osteoblasts with ten fold higher concentrations than those needed for the membrane effects (0.1 microgram/ml and 10 pM, respectively). Both effects were gender-specific since testosterone and 5 alpha-dihydotesterone were uneffective. Tamoxifen and Raloxifene, two estrogen nuclear antagonists, inhibited CK response to 1D5 and E2 and Ca2+ response to 1D5, but not Ca2+ response to E2. By contrast, (Fab')2 dimer, a proteolytic fragment of 1D5 with antagonist properties, inhibited both membrane and genomic effects of 1D5 and E2. In conclusion, these results imply that clone 1D5 has an estrogen like activity both at the membrane and nuclear levels in female human and rat osteoblasts. 1D5 must therefore interact with membrane binding sites, penetrate the cells, and reach the nuclear receptors by an as yet uncharacterized mechanism.     

Pancultural explanations for life satisfaction: adding relationship harmony to self-esteem

The first part of the study confirmed an additive effect of the newly proposed construct of relationship harmony to self-esteem in predicting life satisfaction across student samples from the United States and Hong Kong. As predicted from the dynamics of cultural collectivism, the relative importance of relationship harmony to self-esteem was greater in Hong Kong than in the United States. In the second part of the study, the independent and interdependent self-construals (H. R. Markus & S. Kitayama, 1991) and the 5 factors of personality (P. T. Costa & R. R. McCrae, 1992) were advanced to be the culture-general determinants of life satisfaction, acting through the mediating variables of self-esteem and relationship harmony. Both self-construals and the 5 factors of personality were shown to influence life satisfaction through the mediating agency of self-esteem and relationship harmony in equivalent ways across these 2 cultural groups.     

New pathway of heparan sulphate degradation. Iduronate sulphatase and N-sulphoglucosamine 6-sulphatase act on the polymer chain prior to depolymerisation by a N-sulpho-glucosaminidase and glycuronidases in the mollusc Tagelus gibbus

In current clinical practice, it is important to be able to evaluate the evidence supporting each of our actions. Physicians can no longer rely on tradition or habit; however, with the increasing number of journals available, it is impossible for the practicing clinician to keep abreast of all the relevant literature. One valuable method of gathering and summarizing the latest information and opinions is the use of round tables and consensus conferences. Published reports of round table and consensus conference findings can be invaluable in guiding the clinician.     

Early intervention for schizophrenic disorders. Implementing optimal treatment strategies in routine clinical services. OTP Collaborative Group

BACKGROUND: Early detection and intervention in schizophrenic disorders is an important challenge for psychiatry. METHOD: Review of literature on effective biomedical and psychosocial intervention strategies. RESULTS: Comprehensive programmes of drug and psychosocial interventions with adults who show early signs and symptoms of schizophrenic disorders may contribute to a lower incidence and prevalence of major episodes of schizophrenia. These programmes combine early detection of psychotic features by primary care services, with close liaison with mental health professionals. Long-term monitoring of signs of recurrence, with further intervention, appears essential to maintain these benefits. CONCLUSIONS: Field trials demonstrate that effective early treatment strategies can be routinely applied in clinical practice.     

A neuronal two P domain K+ channel stimulated by arachidonic acid and polyunsaturated fatty acids

TWIK-1, TREK-1 and TASK K+ channels comprise a class of pore-forming subunits with four membrane-spanning segments and two P domains. Here we report the cloning of TRAAK, a 398 amino acid protein which is a new member of this mammalian class of K+ channels. Unlike TWIK-1, TREK-1 and TASK which are widely distributed in many different mouse tissues, TRAAK is present exclusively in brain, spinal cord and retina. Expression of TRAAK in Xenopus oocytes and COS cells induces instantaneous and non-inactivating currents that are not gated by voltage. These currents are only partially inhibited by Ba2+ at high concentrations and are insensitive to the other classical K+ channel blockers tetraethylammonium, 4-aminopyridine and Cs+. A particularly salient feature of TRAAK is that they can be stimulated by arachidonic acid (AA) and other unsaturated fatty acids but not by saturated fatty acids. These channels probably correspond to the functional class of fatty acid-stimulated K+ currents that recently were identified in native neuronal cells but have not yet been cloned. These TRAAK channels might be essential in normal physiological processes in which AA is known to play an important role, such as synaptic transmission, and also in pathophysiological processes such as brain ischemia. TRAAK channels are stimulated by the neuroprotective drug riluzole.     

Patterned epidermal cell death in wild-type and segment polarity mutant Drosophila embryos

Programmed cell death plays an essential role in the normal embryonic development of Drosophila melanogaster. One region of the embryo where cell death occurs, but has not been studied in detail, is the abdominal epidermis. Because cell death is a fleeting process, we have used time-lapse, fluorescence microscopy to map epidermal apoptosis throughout embryonic development. Cell death occurs in a stereotypically striped pattern near both sides of the segment border and to a lesser extent in the middle of the segment. This map of wild-type cell death was used to determine how cell death patterns change in response to genetic perturbations that affect epidermal patterning. Previous studies have suggested that segment polarity mutant phenotypes are partially the result of increased cell death. Mutations in wingless, armadillo, and gooseberry led to dramatic increases in apoptosis in the anterior of the segment while a naked mutation resulted in a dramatic increase in the death of engrailed cells in the posterior of the segment. These results show that segment polarity gene expression is necessary for the survival of specific rows of epidermal cells and may provide insight into the establishment of the wild-type epidermal cell death pattern.