Synthesis of polylactides with different molecular weights

The synthesis of poly(lactic acid) through polycondensation of the lactic acid monomer gave weight average molecular weights (Mw) lower than 1.6 x 10(4), whereas ring-opening polymerization of lactides in bulk at 130 degrees C for 72 h using stannous octoate as catalyst in the concentration range from 0.003 to 0.8 wt% produced polylactides with viscosity average molecular weight (Mv) ranging from 2 x 10(4) to 6.8 x 10(5). The monomer conversion and Mv showed a maximum at a catalyst concentration around 0.05 wt%. The monomer conversion and Mv increased almost linearly with polymerization time up to a monomer conversion of 80%, but both the conversion and Mv decreased after passing through a maximum, when the polymerization reaction was allowed to proceed for longer periods of time. This time dependence was pronounced at higher polymerization temperatures. The decrease in Mv at prolonged polymerization and higher polymerization temperatures was attributed to thermal depolymerization of resultant polylactides, but no significant optical rotation of poly(L-lactide) was noticed.     

Potentiation of miniature endplate potential frequency by ATP in Xenopus tadpoles

1. Extracellular application of ATP (1 mM), a substance co-stored and co-released with acetylcholine in peripheral nervous systems, potentiated the spontaneous secretion of acetylcholine (ACh) but had no effect on the amplitude and decay time constant of miniature endplate potentials (m.e.p.ps) at neuromuscular synapses in Xenopus tadpoles. 2. alpha,beta-Methylene ATP (0.3 mM) and GTP (1 mM) were also effective in increasing m.e.p.p. frequency. On the other hand, ADP, AMP and adenosine (all at 1 mM) decreased m.e.p.p. frequency. 3. Unlike the transient effect of ATP analogue and GTP on m.e.p.p. frequency, the phorbol ester TPA (2 microM) which is a protein kinase C activator, increased m.e.p.p. frequency consistently and the effects lasted as long as the presence of TPA. 4. Staurosporine (0.5 microM) and H-7 (10 microM), which are protein kinase C inhibitors, each decreased the basal level of m.e.p.p. frequency and markedly inhibited the effects of both ATP and TPA. 5. These results suggest that there is a basal activity of cytosolic protein kinases in the nerve terminals of Xenopus tadpoles and the effect of ATP is probably mediated by the binding of membrane surface purinoceptors which in turn activates cytosolic protein kinases and increases ACh release.     

Lethal tuberculosis in interleukin-6-deficient mutant mice

Tuberculosis is a chronic infectious disease which causes major health problems globally. Acquired resistance is mediated by T lymphocytes and executed by activated macrophages. In vitro studies have emphasized the importance of macrophage activation for mycobacterial growth inhibition. In vivo, the protective host response is focused on granulomatous lesions in which Mycobacterium tuberculosis is contained. A cellular immune response of the T helper 1 (Th1) type is considered central for control of tuberculosis. Using interleukin-6 (IL-6)-deficient mice, we here demonstrate a crucial role of this pluripotent cytokine in protection against M. tuberculosis but not against Mycobacterium bovis BCG. Infection with M. tuberculosis was lethal for the IL-6-deficient mice at inocula that were still controlled by IL-6-competent mice. Spleen cells from M. tuberculosis-infected IL-6-/- mouse mutants produced elevated levels of IL-4 and reduced levels of gamma interferon compared to the control levels. Cytofluorometric analyses of spleen cells from M. tuberculosis-infected mice revealed more-profound alterations in T-cell ratios in IL-6-/- mice than in control mice. We assume that IL-6 contributes to host resistance by its proinflammatory activity and by its influence on cytokine secretion.     

Protein-nucleic acid interactions and DNA conformation in a complex of human immunodeficiency virus type 1 reverse transcriptase with a double-stranded DNA template-primer

Myocardial glucose metabolism has been shown to be heterogeneous in patients with hypertrophic cardiomyopathy (HCM). We tested the hypothesis that myocardial glucose metabolism differs between patients with HCM and those with hypertensive heart disease (HHD) associated with asymmetrical septal hypertrophy. We studied 12 patients with HCM, 7 HHD patients associated with asymmetrical septal hypertrophy using 18F 2-deoxyglucose (FDG) and positron emission tomography. We calculated % FDG fractional uptake in the inter-ventricular septum and posterolateral wall. Heterogeneity of FDG uptake was evaluated by % interregional coefficient of variation of FDG fractional uptake in each wall segment. In both the interventricular septum and posterolateral wall, % FDG fractional uptake was not significantly different between the two groups. The % interregional coefficient of variation for both interventricular septum (10.6 +/- 1.6 vs. 4.1 +/- 0.5, p < 0.01) and posterolateral wall (5.9 +/- 0.7 vs. 3.8 +/- 0.5, p < 0.05) was significantly larger in patients with HCM than in HHD patients associated with asymmetrical septal hypertrophy. Echocardiography demonstrated that the degree of asymmetrical septal hypertrophy was similar between the two groups. These results suggest that myocardial glucose metabolism may be more heterogeneous in patients with HCM compared to HHD patients associated with asymmetrical septal hypertrophy, although the left ventricular shape is similar. The difference in the heterogeneity might have resulted from differences in the pathogeneses of the two diseases.     

A Meta-Analysis of Primate Hand Preferences, Particularly for Reaching.

P. F. MacNeilage, M. G. Studdert-Kennedy, and B. Lindblom (1987) proposed a progression for handedness in primates that was supposed to account for the evolution of a right bias in human handedness. To test this proposal, the authors performed meta-analyses on 62 studies that provided individual data (representing 31 species: 9 prosimians, 6 New World monkeys, 10 Old World monkeys, 2 lesser apes, and 4 greater apes), of the 118 studies of primate handedness published since 1987. Although evidence of a population-level left-handed bias for prosimians and Old World monkeys supports P. F. MacNeilage et al., the data from apes, New World monkeys, and individual species of prosimians and New World monkeys do not. Something other than primate handedness may have been the evolutionary precursor of the right bias in hand-use distribution among hominids. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social Cognitive Predictors of Academic Interests and Goals in Engineering: Utility for Women and Students at Historically Black Universities.

This study examined the utility of social cognitive career theory (SCCT; R. W. Lent, S. D. Brown, & G. Hackett, 1994) in predicting engineering interests and major choice goals among women and men and among students at historically Black and predominantly White universities. Participants (487 students in introductory engineering courses at 3 universities) completed measures of academic interests, goals, self-efficacy, outcome expectations, and environmental supports and barriers in relation to engineering majors. Findings indicated that the SCCT-based model of interest and choice goals produced good fit to the data across gender and university type. Implications for future research on SCCT's choice hypotheses, and particularly for the role of environmental supports and barriers in the choice of science and engineering fields, are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Social Cognitive Predictors of Domain and Life Satisfaction: Exploring the Theoretical Precursors of Subjective Well-Being.

Central variables of social cognitive theory were adapted to forge an integrative model of well-being, which was designed to offer greater utility for therapeutic and self-directed change efforts than the dominant personality view of well-being. The authors present 2 studies using versions of the social cognitive model to predict domain-specific and overall life satisfaction. In both studies--one nomothetic, the other idiographic in measurement approach--findings indicated that satisfaction in particular life domains is predicted by domain-specific social cognitive variables (e.g., self-efficacy, perceived goal progress, environmental resources). Domain satisfaction in valued life domains also explained unique variance in overall life satisfaction, even after controlling for trait positive affectivity or extraversion. Implications for theory, research, and counseling aimed at well-being promotion and maintenance are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Invasive mold sinusitis: 17 cases in immunocompromised patients and review of the literature

A 10-year retrospective analysis of invasive mold infections in hospitalized patients was performed to characterize the epidemiology and clinical features of invasive fungal sinusitis. Seventeen cases of invasive mold sinusitis were identified. Eleven cases were caused by Aspergillus flavus, three were caused by unspecified species, and one each was caused by Aspergillus fumigatus, Rhizopus species, and Alternaria species, respectively. Fifteen patients had hematologic malignancies, and two had end-stage liver disease. The most common presenting symptom was periorbital swelling (seven patients). Sinusitis was diagnosed a median of 19 days after admission. Eight patients (47%) survived; six of these patients were treated with both amphotericin B and surgery. Postmortem examination of six patients showed evidence of disseminated disease; the brain was the most common extrapulmonary site (four patients). To our knowledge, this is the largest currently reported series on invasive mold sinusitis; our report extends the information on invasive mold sinusitis and shows that aggressive therapeutic and surgical interventions are needed to prevent rapid progression of disease in immunocompromised patients.