Activation of salivary secretion: coupling of cell volume and [Ca2+]i in single cells

High-resolution differential interference contrast microscopy and digital imaging of the fluorescent calcium indicator dye fura-2 were performed simultaneously in single rat salivary gland acinar cells to examine the effects of muscarinic stimulation on cell volume and cytoplasmic calcium concentration ([Ca2+]i). Agonist stimulation of fluid secretion is initially associated with a rapid tenfold increase in [Ca2+]i as well as a substantial cell shrinkage. Subsequent changes of cell volume in the continued presence of agonist are tightly coupled to dynamic levels of [Ca2+]i, even during [Ca2+]i oscillations. Experiments with Ca2+ chelators and ionophores showed that physiological elevations of [Ca2+]i are necessary and sufficient to cause changes in cell volume. The relation between [Ca2+]i and cell volume suggests that the latter reflects the secretory state of the acinar cell. Agonist-induced changes in [Ca2+]i, by modulating specific ion permeabilities, result in solute movement into or out of the cell. The resultant cell volume changes may be important in modulating salivary secretion.     

Elemental and redox analysis of single bacterial cells by x-ray microbeam analysis

High-energy x-ray fluorescence measurements were used to make elemental maps and qualitative chemical analyses of individual Pseudomonas fluorescens strain NCIMB 11764 cells. Marked differences between planktonic and adhered cells were seen in the morphology, elemental composition, and sensitivity to Cr(VI) of hydrated cells at spatial scales of 150 nm. This technology can be applied to natural geomicrobiological systems.     

Microcolumn separations and the analysis of single cells

Capillary zone electrophoresis and open tubular liquid chromatography are two examples of an emerging area of analytical instrumentation known as microcolumn separations. The high resolution and small sample requirements of these methods make them suitable for the quantitative, multicomponent chemical analysis of single cells. Appropriate instrumentation for the analysis of nanoliter and subnanoliter samples is discussed. Data from the analysis of individual neurons are presented, including amino acid and neurotransmitter content.     

Constitutive display of cryptic translation products by MHC class I molecules

Major histocompatibility complex (MHC) class I molecules display tens of thousands of peptides on the cell surface, derived from virtually all endogenous proteins, for inspection by cytotoxic T cells (CTLs). We show that, in normal mouse cells, MHC I molecules present a peptide encoded in the 3' "untranslated" region. Despite its rarity, the peptide elicits CTL responses and induces self-tolerance, establishing that immune surveillance extends well beyond conventional polypeptides. Furthermore, translation of this cryptic peptide occurs by a previously unknown mechanism that decodes the CUG initiation codon as leucine rather than the canonical methionine.     

免疫胶体金法快速检测水产品中喹诺酮类药物

利用QH12杂交瘤细胞株生产抗体,研制高灵敏度的免疫胶体金试剂条,其对洛美沙星、氧氟沙星、诺氟沙星、培氟沙星的最低检出限分别为2.0、2.5、2.5、5.0 ng·mL^-1。通过样品预处理方法优化,建立免疫胶体金快速检测方法(GICT)。将其与HPLC法进行比较,并用LC-MS/MS法验证效果。结果表明,GICT灵敏度高于HPLC法,检测结果与LC-MS/MS法较一致,单个样品检测耗时25 min。综合比较分析,GICT宜作为水产品中喹诺酮类药物残留的快速筛查检测方法进行推广。     

Homograft target cells: contact destruction in vitro by immune macrophages

Specific adherence of immune macrophages to monolayers of target cells is a passive phenomenon which represents only the first step in the mutually destructive interaction of immune macrophages and target cells. A specific hemagglutinin, responsible for specific adherence, was eluted from well-washed immune macrophages by heat treatment. The nature of the events in the interaction subsequent to adherence are unknown, but apparently demand the biosynthetic activities of the immune macrophage.     

Hemoglobin aggregation in single red blood cells of sickle cell anemia

A laser light scattering technique was used to observe the extent of hemoglobin aggregation in solitary red blood cells of sickle cell anemia. Hemoglobin aggregation was confirmed in deoxygenated cells. The light scattering technique can also be applied to cytoplasmic studies of any biological cell.     

Programmed cell death of T cells signaled by the T cell receptor and the alpha 3 domain of class I MHC

As well as being activated or rendered unresponsive, mature T lymphocytes can be deleted, depending on the signals received by the cell. Deletion by programmed cell death (apoptosis) is triggered if a T cell that has received a signal through its T cell receptor complex also receives a signal through the alpha 3 domain of its class I major histocompatibility complex (MHC) molecule. Such a signal can be delivered by a CD8 molecule, which recognizes the alpha 3 domain, or by an antibody to this domain. Precursors of both cytotoxic T lymphocytes (CTL's) and T helper cells are sensitive to this signal but become resistant at some point before completing differentiation into functioning CTL's or T helper cells. Because CTL's carry CD8, they can induce cell death in T cells that recognize them. This pathway may be important in both removal of autoreactive T cells and immunoregulation.     

Transformation of human lymphocytes: inhibition by homologous alpha globulin

An alpha globulin fraction prepared from normal human plasma by column chromatography prevents homologous lymphocyte transformation and the stimulation of DNA, and also protein synthesis induced by phytohemagglutinin and specific antigens. These observations support the concept of a normal circulating immunosuppressant factor which prevents lymphoid cell proliferation.     

促黄体素(LH)对猪卵巢颗粒细胞细胞周期及类固醇激素分泌的影响

为揭示促黄体素对猪卵巢颗粒细胞生长及类固醇分泌的影响,从当地屠宰场采集猪卵巢,选择表面直径大于6 mm的卵泡(优势卵泡)作为试验材料,将从其中获得的颗粒细胞进行体外培养,并在培养基中添加不同浓度(0 IU/ml、2 IU/ml和4 IU/ml)的促黄体素(LH),通过流式细胞仪、放射性免疫和定量PCR分别检测细胞周期的...     

Promotion of tissue inflammation by the immune receptor Tim-3 expressed on innate immune cells

CD4+ T helper 1 (TH1) cells are important mediators of inflammation and are regulated by numerous pathways, including the negative immune receptor Tim-3. We found that Tim-3 is constitutively expressed on cells of the innate immune system in both mice and humans, and that it can synergize with Toll-like receptors. Moreover, an antibody agonist of Tim-3 acted as an adjuvant during induced immune responses, and Tim-3 ligation induced distinct signaling events in T cells and dendritic cells; the latter finding could explain the apparent divergent functions of Tim-3 in these cell types. Thus, by virtue of differential expression on innate versus adaptive immune cells, Tim-3 can either promote or terminate TH1 immunity and may be able to influence a range of inflammatory conditions.     

应用草鱼吻端成纤维细胞分析海水致病性弧胞外产物的毒性

采用盐析法提取3株海水鱼类致病性弧菌的胞外产物(ECPs),并应用草鱼吻端成纤维(PSF)细胞分别对ECPs进行细胞毒性分析。结果表明,3种ECPs对PSF细胞都有毒性作用,可引起不同类型的细胞病变,且不同ECPs导致细胞可见病变的浓度不同:副溶血弧菌AnGS020501在0.125μg/mL时可致细胞病变,哈维氏弧菌EcGY020401的致细胞病变浓度为2.0μg/mL,哈维氏弧菌SpGY020601为4.0μg/mL。溶血性和动物毒性研究表明,3种ECPs细胞毒性与溶血性、动物毒性有一定的相关性。PSF细胞可应用于弧菌ECPs的体外毒性评价中。     

Contact-dependent demyelination by Mycobacterium leprae in the absence of immune cells

Demyelination results in severe disability in many neurodegenerative diseases and nervous system infections, and it is typically mediated by inflammatory responses. Mycobacterium leprae, the causative organism of leprosy, induced rapid demyelination by a contact-dependent mechanism in the absence of immune cells in an in vitro nerve tissue culture model and in Rag1-knockout (Rag1-/-) mice, which lack mature B and T lymphocytes. Myelinated Schwann cells were resistant to M. leprae invasion but undergo demyelination upon bacterial attachment, whereas nonmyelinated Schwann cells harbor intracellular M. leprae in large numbers. During M. leprae-induced demyelination, Schwann cells proliferate significantly both in vitro and in vivo and generate a more nonmyelinated phenotype, thereby securing the intracellular niche for M. leprae.     

T-Independent immune response: new aspects of B cell biology

Recent results emphasize the roles of T-independent antibody response in humoral defenses, for which B1 cells and marginal zone B cells are mostly responsible. We discuss how these cells are activated, migrate, and differentiate into antibody-producing cells in various lymphoid tissues. Based on recent findings in each of these areas of B cell biology, we propose a possible mechanism for peripheral tolerance of autoreactive B cells at target organs.     

Apparent production of 2 types of antibdoies by a single cell

Immunization of mice with bacterial, sheep red cells coated with antigen resulted in apparent production of antibody-forming plaques with specificities for both hemolysis and bactericidal activity. The secondary response for production of these bifunctional types of plaques could be induced by red blood cells or bacteria alone. A significant mutual suppression of immune response between the two immunizing agents was observed.     

Behavioral acts elicited by stimulation of single, identifiable brain cells

By stimulation of and recording from all of the nerve trunks and from over 50 of the large nerve cell bodies in the isolated brain of the nudibranch Tritonia gilberti a map of the axonal paths and synaptic connections has been constructed. The nervous correlates of sensory and motor activities can be monitored in single cells of the intact animal. Similarly, discrete responses in local muscles of the body wall and complex behavioral sequences such as turning and swimming are triggered by stimulation of single identifiable units.     

Cell proliferation: enhancement by extracts from cell surfaces of polyoma-virus-transformed cells

Dispersion of confluent monolayers of BHK21 cells with ethylenediaminetetraacetate yields a material that inhibits cell proliferation, whereas identical extraction of polyoma-virus-transformed cells provides material which enhances cellular proliferation. The material was partially characterized.     

B细胞活化因子及调节性T细胞在免疫性血小板减少症发病中的作用

目的 了解B细胞活化因子(BAFF)及调节性T(Treg)细胞在免疫性血小板减少症(ITP)发病中的作用.方法 采集34例ITP及28例健康对照者外周血,用流式细胞术检测外周血Treg细胞数,ELISA检测血浆BAFF水平.结果 ITP患者外周血Treg细胞/CD4+细胞比值低于对照者[(1.55±1.13)％ vs (2.73±0.83)％,P＜0.01],而血浆BAFF水平高于对照者[(1 426.14±1 280.67) μg/L vs (644.29±307.97) μg/L,P＜0.01].结论 BAFF与Treg细胞可能存在相互作用,从而参与ITP发病.     

Translocation of Helicobacter pylori CagA into gastric epithelial cells by type IV secretion

The Gram-negative bacterium Helicobacter pylori is a causative agent of gastritis and peptic ulcer disease in humans. Strains producing the CagA antigen (cagA(+)) induce strong gastric inflammation and are strongly associated with gastric adenocarcinoma and MALT lymphoma. We show here that such strains translocate the bacterial protein CagA into gastric epithelial cells by a type IV secretion system, encoded by the cag pathogenicity island. CagA is tyrosine-phosphorylated and induces changes in the tyrosine phosphorylation state of distinct cellular proteins. Modulation of host cells by bacterial protein translocation adds a new dimension to the chronic Helicobacter infection with yet unknown consequences.     

Activation of single lateral geniculate cells by stimulation of either optic nerve

The lateral geniculate nucleus is organized in such a way that, initially at least, information from the one eye is almost exclusively segregated from that from the other eye. Single-unit recording, however, confirms the histological evidence that bilateral integration does take place. A small number of cells (< 8.5 percent) receive afferents directly from both optic nerves and are discharged by stimulating either nerve (direct interaction). More common is delayed interaction, where the cells are discharged independently by either optic nerve but only after a relatively long latency. Indirect interaction effects also occur.