SAP97 is associated with the alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid receptor GluR1 subunit

Rapid glutamatergic synaptic transmission is mediated by ionotropic glutamate receptors and depends on their precise localization at postsynaptic membranes opposing the presynaptic neurotransmitter release sites. Postsynaptic localization of N-methyl-D-aspartate-type glutamate receptors may be mediated by the synapse-associated proteins (SAPs) SAP90, SAP102, and chapsyn-110. SAPs contain three PDZ domains that can interact with the C termini of proteins such as N-methyl-D-aspartate receptor subunits that carry a serine or threonine at the -2 position and a valine, isoleucine, or leucine at the very C terminus (position 0). We now show that SAP97, a SAP whose function at the synapse has been unclear, is associated with alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA)-type glutamate receptors. AMPA receptors are probably tetramers and are formed by two or more of the four AMPA receptor subunits GluR1-4. GluR1 possesses a C-terminal consensus sequence for interactions with PDZ domains of SAPs. SAP97 was present in AMPA receptor complexes immunoprecipitated from detergent extracts of rat brain. After treatment of rat brain membrane fractions with the cross-linker dithiobis(succinimidylpropionate) and solubilization with sodium dodecylsulfate, SAP97 was associated with GluR1 but not GluR2 or GluR3. In vitro experiments with recombinant proteins indicate that SAP97 specifically associates with the C terminus of GluR1 but not other AMPA receptor subunits. Our findings suggest that SAP97 may be involved in localizing AMPA receptors at postsynaptic sites through its interaction with the GluR1 subunit.     

Study on the weathering resistance of fly ash-lime compacts

The relationship between the inner quality factors (such as the amount of effective calcium oxide and the pore structure) of steam-cured fly ash-lime compacts (clinker-free) and the environment factors (such as drying shrinkage, freeze-thaw and carbonation, et cetera) have been studied here comprehensively by the simulation weathering examination. Meanwhile, the influences of additives of alkali paste and gypsum on the mechanical properties and pore structure of the compacts have been investigated and discussed, and the effects of interface texture on the mechanical properties have been discussed also. The results suggest that the weathering resistance of the system studied can be improved effectively by means of controlling the fraction of effective calcium oxide (EF_cao) and additives, in turn, to improve the interface interlinking. The optimum fraction of EF_cao is ∼15.3%, alkali paste is about 3.0% and gypsum is 1.7∼2.6% (account by SO₃%) if the as-received low calcium-bearing fly ash with low carbon content (<6.0%) has been selected.     

Instability of tuberculin and Candida skin test reactivity in HIV-infected Ugandans. The Uganda-Case Western Reserve University Research Collaboration

Anergy testing has been used as an adjunct to tuberculin testing for assessing M. tuberculosis (MTB) infection and indications for isoniazid preventive therapy in HIV-infected persons. We examined factors associated with the stability of skin test responses to purified protein derivative (PPD) and candida antigens in a cohort of HIV-infected adults followed prospectively in a tuberculosis preventive therapy trial in Uganda. PPD-positive and anergic subjects in the placebo arms of the preventive therapy study underwent repeat skin testing and immunologic testing including measurement of MTB culture filtrate (CF)-stimulated interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha) levels in whole-blood culture supernatants. Anergy was present in 27% of 4,058 HIV-infected subjects screened for the tuberculosis preventive therapy trial compared with 10% of 682 HIV-non-infected persons. On follow-up testing of enrolled subjects, 42% of 139 initially anergic subjects were no longer anergic; two thirds of these had PPD reactions >= 5 mm. Stability of anergy was associated with intercurrent opportunistic infections and AIDS-associated dermatitis at baseline. Thirty-five percent of 313 subjects with an initial positive PPD had a negative PPD test at follow-up, 26% of whom had a positive candida skin test at the same time as the negative PPD test. Baseline MTBCF-stimulated IFN-gamma levels were significantly higher among PPD-positive subjects who remained PPD-positive than in those who were falsely negative. We conclude first that anergy is unstable and second that anergy testing is unreliable in identifying HIV-infected adults who are not infected with MTB and should not be used routinely for this purpose in assessing indications for isoniazid preventive therapy.     

Confirmed previous infection with Chlamydia pneumoniae (TWAR) and its presence in early coronary atherosclerosis

BACKGROUND: Chlamydia pneumoniae has been identified in coronary atheroma, but concomitant serum antibody titers have been inconsistently positive and unavailable before the detection of early or advanced atherosclerotic lesions. METHODS AND RESULTS: This retrospective investigation was performed on premortem serum specimens and autopsy tissue from 60 indigenous Alaska Natives at low risk for coronary heart disease, selected by the potential availability of their stored specimens. Serum specimens were drawn a mean of 8.8 years (range, 0.7 to 26.2 years) before death, which occurred at a mean age of 34.1 years (range, 15 to 57 years), primarily from noncardiovascular causes (97%). Coronary artery tissues were independently examined histologically and, for C pneumoniae organism and DNA, by immunocytochemistry (ICC) and polymerase chain reaction (PCR) with species-specific monoclonal antibody and primers. Microimmunofluorescence detected species-specific IgG, IgA, and IgM antibody in stored serum. C pneumoniae, frequently within macrophage foam cells, was identified in coronary fibrolipid atheroma (raised lesions, Stary types II through V) in 15 subjects (25%) and early flat lesions in 7 (11%) either by PCR (14, 23%) or ICC (20, 33%). The OR for C pneumoniae in raised atheroma after a level of IgG antibody > or =1:256 >8 years earlier was 6.1 (95% CI, 1.1 to 36.6) and for all coronary tissues after adjustment for multiple potential confounding variables, including tobacco exposure, was 9.4 (95% CI, 2.6 to 33.8). CONCLUSIONS: Serological evidence for C pneumoniae infection frequently precedes both the earliest and more advanced lesions of coronary atherosclerosis that harbor this intracellular pathogen, suggesting a chronic infection and developmental role in coronary heart disease.     

Managing DNR requests in the school setting

Control and alleviation of pain in the care to children with cancer are objects of nursing concern in the search for interventions that are able to minimize or avoid physical-emotional problems in these children. Medical, psychological and nursing literatures describe pain through physiological, emotional, behavioural and environmental aspects in several models of scales of pain evaluation and control. This study describes some models of evaluation of pain in children and presents the adaptation of the Scale Model of Visual Analogy of Faces by McGrath (1990), as an instrument to be used in nursing care to children with cancer. Although the literature utilized on this study gives emphasis on the evaluation and control of pain in children with cancer, we verify the viability of applying this model by nursing in other situations of pain.     

Acute and chronic ethanol increases reactive oxygen species generation and decreases viability in fresh, isolated rat hepatocytes

Although reactive oxygen species (ROS) have been implicated in the etiology of alcohol-induced liver disease, neither their relative contribution to cell death nor the cellular mechanisms mediating their formation are known. The purpose of this study was to test the hypothesis that acute and chronic ethanol exposure enhances the mitochondrial generation of ROS in fresh, isolated hepatocytes. Acute ethanol exposure stimulated ROS production, increased the cellular NADH/NAD+ ratio, and decreased hepatocyte viability slightly, which was prevented by pretreatment with 4-methylpyrazole (4-MP), an inhibitor of alcohol dehydrogenase. Similarly, xylitol, an NADH-generating compound, enhanced hepatocyte ROS production and decreased viability. Incubation with pyruvate, an NADH-oxidizing compound, and cyanamide, an inhibitor of aldehyde dehydrogenase, significantly decreased ROS levels in acute ethanol-treated hepatocytes. Chronic ethanol consumption produced a sixfold increase in hepatocyte ROS production compared with levels measured in controls. Hepatocytes from ethanol-fed rats were less viable compared with controls, e.g., viability was 68% +/- 2% (ethanol) versus 83% +/- 1% (control) after 60 minutes of incubation. Antimycin A increased ROS production and decreased cell viability; however, the toxic effect of antimycin A was more pronounced in ethanol-fed hepatocytes. These results suggest that acute and chronic ethanol exposure exacerbates mitochondrial ROS production, contributing to cell death.     

黄河断流与生态环境保护的思考

近年来，黄河下游频繁出现断流现象。面对黄河日益严重的断流形势，本文从可持续发展战略和生态环境保护的高度，认真思考黄河断流和生态环境问题，并探讨解决黄河断流的有效途径。     

Improvement of signal-to-noise and contrast-to-noise ratios in dual-screen computed radiography

A dual-screen computed radiography (CR) technique has been developed to improve and optimize the overall image signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). With this technique, two CR screens are exposed together and separately scanned to form a front and a back image. These two images are then superimposed to form an image of improved SNR and CNR. A mathematical model has been derived to describe the improvement and optimization of the SNR and CNR. Based on this model, the front and back images should be weighted in proportion to their SNR squared to optimize the SNR of the composite image. Imaging experiments have been conducted to verify the theoretical model under mammographic and chest imaging conditions. The results largely agree with the theoretical predictions. It has also been found that optimization of the SNR results in nearly optimal CNR and vice versa. For mammographic imaging, a 14%-22% improvement in the SNR and a 13%-19% improvement in the CNR have been demonstrated. For chest imaging, a 31%-36% improvement in the SNR and a 28%-30% improvement in the CNR has been demonstrated.