Interleukin 1-induced lymphocyte binding to endothelial cells. Role of cAMP as a second messenger

Interleukin 1 (IL 1) is a potent protein mediator of inflammation. Among other things it increases the number of lymphocytes adhering to endothelial cell monolayers. We analyzed the signal transduction during IL 1-induced lymphocyte binding. Dibutyryl cyclic AMP, which is a cAMP analog able to penetrate into the cytosol, increased lymphocyte binding to the same extent as IL 1. Direct activation of adenylate cyclase by forskolin enhanced also lymphocyte binding. IL 1 increased the level of cytosolic cAMP in a time- and dose-dependent manner measured with radioimmunoassay. 2',5'-Dideoxyadenosine, which is an inhibitor of adenylate cyclase, decreased both the IL 1-induced lymphocyte binding to endothelial cells and elevation in cytosolic cAMP levels. Lymphocyte binding increased with cytosolic cAMP levels in accordance with elevation of IL 1 concentration. These results suggest that cAMP is essential in signal transduction during IL 1-induced lymphocyte binding to cultured endothelial cell monolayers.     

Properties of B cells and Thy-1-antigen-expressing cells infiltrating rat renal allografts

We have examined (1) the frequency of B cells secreting antibodies against donor major histocompatibility complex (MHC) antigens and (2) the properties of Thy-1-antigen-expressing leukocytes in rats rejecting renal allografts. Our results show that B cells secreting antibodies are present in the inflammatory cell population at the frequency of 1:850. Among them only 1 out of 2-150 is engaged in production of antibodies directed to the graft MHC antigens, depending on the method of assay. This suggests that despite the observed significant production of nonspecific immunoglobulin in situ, only a minority of the B-cell population is specifically committed to the graft MHC antigens. This finding is concordant with the described previously low frequencies of the T cells specifically directed toward the graft MHC antigen. The role of the "immunologically noncommitted" cells in graft rejection is unknown. We have found that a substantial part (up to 60%) of inflammatory cells invading a rat kidney allograft express the Thy-1 antigen. This suggests that they might be immature (progenitor?) cells and, therefore, unable to respond to the graft antigens. Progenitor-like properties of these cells have been confirmed by their ability to reconstitute lethally irradiated syngeneic rat. Finally, these immature cells are of lymphoid, not of myeloid, linkage, because they do not proliferate in the presence of GM-CSF.     

Fatal meningoencephalitis due to Bacillus anthracis

Abstract: We report the first case of fatal anthrax meningoencephalitis in Hong Kong over the past 60 years. A 13 year-old boy presented with right lower quadrant pain, diarrhoea and progressive headache. Lumbar puncture yielded gram positive bacilli initially thought to be Bacillus cereus, a contaminant. He was treated with ampicillin and cefotaxime, but died 3 days after hospitalization. The organism isolated from blood and cerebrospinal fluid was later identified as Bacillus anthracis.     

β-阻滞剂塞利洛尔的合成

报道了β－阻滞剂塞利洛尔的简便制备方法，即以对乙氧基苯胺为原料，经酰胺化，傅克反应，以环氧氯丙烷取代，最后用叔丁胺直接与环氧基反应开环等４步反应制得。比文献五步反应缩短了一步，产物经元素分析、红外光谱、核磁共振谱、质谱等分析确定结构。     

正常人口服磷酸川芎嗪的药代动力学研究

本文建立了用高效液相色谱法测定人体内川芎嗪血药浓度的方法,以C18化学键合硅胶(10μgm)为固定相,以甲醇—水(58:42)为流动相,280 nm俭测,安眠酮为内标,进行定量测定,得出俭测限为3.5 ng(S/N=4),最低检测血清浓度为17.4 ng/ml,川芎嗪血药浓度在0.029～5.82μg/ml范围内,线性关系良好,方法回收率为99.84%。方法重现性好,专一性强,内源性物质、代谢产物及同时服用的药物均不干扰。用本法测定了健康人口服川芎嗪的药代动力学参数。     

Scattering Analysis of AlGaN/AlN/GaN Heterostructures with Fe-Doped GaN Buffer

The results of the study of the influence of Fe segregation into the unintentionally doped GaN channel layer in AlGaN/AlN/GaN heterostructures with Fe-doped GaN buffer layer on the electrical properties of two-dimensional electron gas are presented. A set of several samples was grown by metal-organic vapor-phase epitaxy and characterized by the van der Pauw method. The dependence of concentration and mobility of the two-dimensional electron gas on the channel layer thickness was analyzed theoretically by self-consistent solving of 1D Poisson and Schrödinger equations and scattering rate calculations within the momentum relaxation time approximation. It was found that both concentration and mobility decreases were responsible for the increase in the sheet resistance in the structures with a thinner channel layer, with a drop in mobility being not only due to ionized impurity scattering, but also due to a combined effect of weakening of screening, lower carrier energy and change in form-factors on scattering by interface roughness, dislocations and polar optical phonons.     

Escherichia coli tetracycline efflux determinants in relation to tetracycline residues in chicken

ObjectiveTo screen for Escherichia coli (E. coli) resistant to tetracycline, followed by identification of tet efflux genes by polymerase chain reaction (PCR). In addition, detection of tetracycline residues in chicken livers and kidneys were conducted using high performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS).MethodsStrains of E. coli were isolated from samples of chicken colon and screened for tetracycline resistance. Tetracycline genes conferring resistance (Tc^r) were detected by polymerase chain reaction (PCR). Most of the isolates were resistant to tetracycline (97.9%).ResultsPCR analysis indicated that Tc^r E. coli R-plasmids contained tet(A), tet(B) and a combination of both efflux genes. None of the isolates contained other efflux tet genes tet (C, D, E and Y). High performance liquid chromatography-tandem quadrupole mass spectrometry (HPLC-MS-MS), a sensitive technique, was used to detect residues of chlortetracycline (CTC), oxytetracycline (OTC), doxycycline (DC) in chicken livers and kidneys. The samples containing tetracycline residues were at 0.13-0.65 pg/μL levels.ConclusionsTetracycline and other antibiotics are commonly used in the poultry and meat production industry for prevention of microbial infections. Multiple antibiotic resistant bacteria in Oman have increased to alarming levels, threatening public health, domestic and may have adverse effect on environment.