Glycoprotein C of herpes simplex virus 1 acts as a receptor for the C3b complement component on infected cells

Receptors for the Fc portion of immunoglobulins or for the third component of complement (C3) are present on a variety of circulating and fixed tissue cells including granulocytes, monocytes, lymphocytes and glomerular epithelial cells. Cells which lack Fc receptors may express them after infection by herpes simplex virus (HSV)-1, HSV-2, cytomegalovirus or varicella zoster virus. We recently reported that infection by HSV-1 induces both Fc and C3 receptors on human endothelial cells. Glycoprotein E of HSV-1 has been shown to function as an Fc receptor. We now demonstrate that glycoprotein C (gC) of HSV-1 functions as a C3b receptor. This receptor appears following HSV-1, but not HSV-2, infection. Detection of the C3b receptor is blocked by monoclonal antibodies to glycoprotein C (gC) of HSV-1, but not by monoclonal antibodies to other HSV-1 glycoproteins. In addition, the MP mutant of HSV-1, which lacks gC, fails to express a C3b receptor. These results assign a new function of gC of HSV-1 and demonstrate potentially important differences between HSV-1 and HSV-2 glycoproteins.     

类镍Mo14+离子3d94s,3d94p,3d94d组态原子参数的计算

用多组态自洽场方法 ,结合我们提出的半经验拟合公式 ,计算了高离化态类镍Mo14 + 离子 3d94s,3d94p ,3d94d组态的能级、波长和振子强度 ,并与实验符合得较好     

A molecular basis for the two locus model of human complement component C4

The major histocompatibility complex(MHC)-linked fourth component of complement (C4) shows a high degree of polymorphism in several animal species. In man C4 polymorphism was detected by distinct charge differences of the variants. O'Neill et al. showed that this C4 polymorphism was controlled by two closely linked genetic loci, F (C4A) and S (C4B) and these results were extended by Awdeh et al. with an improved typing method. Biochemical analysis of human C4 has revealed that it consists of three polypeptide chains, alpha, beta and gamma. In all reports so far on the molecular analysis of human C4, no molecular weight differences between the A and B locus-encoded molecules have been noticed. Here we demonstrate that the C4A and C4B locus-encoded alpha-chains have a molecular weight (MW) of 96,000 and 94,000, respectively, presenting for the first time a molecular basis for the difference between all C4A and C4B variants tested. Even rare variants that are difficult to allocate to the A or B locus on the basis of charge differences could be identified as C4A or C4B variants in this way, thereby providing new insights into the relationships between the C4A and C4B loci.     

Structures of complement component C3 provide insights into the function and evolution of immunity

The mammalian complement system is a phylogenetically ancient cascade system that has a major role in innate and adaptive immunity. Activation of component C3 (1,641 residues) is central to the three complement pathways and results in inflammation and elimination of self and non-self targets. Here we present crystal structures of native C3 and its final major proteolytic fragment C3c. The structures reveal thirteen domains, nine of which were unpredicted, and suggest that the proteins of the alpha2-macroglobulin family evolved from a core of eight homologous domains. A double mechanism prevents hydrolysis of the thioester group, essential for covalent attachment of activated C3 to target surfaces. Marked conformational changes in the alpha-chain, including movement of a critical interaction site through a ring formed by the domains of the beta-chain, indicate an unprecedented, conformation-dependent mechanism of activation, regulation and biological function of C3.     

Growth induced by pulsatile infusion of an amidated fragment of human growth hormone releasing factor in normal and GHRF-deficient rats

The discovery of human pancreatic growth hormone releasing factors (GHRFs) and subsequent characterization of human hypothalamic GHRF has led to studies on the role of these peptides in stimulating growth hormone (GH) release, and attempts to use GHRF peptides to increase growth rates in short children are already underway. However, there is no experimental evidence in animals that exogenous GHRF promotes growth in vivo. Although anaesthetized rats release GH reproducibly in response to GHRF injections, the responses in conscious male rats are much more variable, perhaps because of their highly episodic endogenous GH secretory pattern. In contrast, female rats secrete GH in a more continuous pattern and respond reproducibly to repeated injections of GHRF. We report here that it is possible to establish a 'male' type of GH secretory pattern in normal female rats by long-term pulsatile intravenous (i.v.) infusions of the active human GHRF fragment GHRF (1-29)NH2. We found that this treatment accelerates growth and increases pituitary GH content, whereas continuous infusions of this GHRF fragment at the same daily dose are ineffective. Pulsatile, but not continuous GHRF also stimulates growth in animals made GHRF-deficient by neonatal monosodium glutamate treatment. Thus exogenous GHRF will stimulate growth in both GHRF-deficient and normal animals provided it is administered in an appropriate pattern.     

Specific antigen-Ia activation of transfected human T cells expressing murine Ti alpha beta-human T3 receptor complexes

The genes encoding the alpha and beta chains of the T-cell receptor (Ti) of an antigen-specific, Ia-restricted murine T-cell hybridoma were introduced into T3-positive or T3-negative human T cells. The resultant transfectants express either mouse-human or mouse-mouse Ti alpha beta molecules functionally associated with the human T3 complex. Only the complete murine Ti alpha beta dimer mediates specific functional corecognition of the appropriate antigen-Ia pair.     

Growth of human breast cancer cells inhibited by a luteinizing hormone-releasing hormone agonist

About one-third of human breast cancers require hormones for their continued growth and endocrine ablation or anti-hormone therapy can cause regression of these tumours. As a consequence, ovariectomy in premenopausal women or administration of an anti-oestrogen (tamoxifen) in postmenopausal women represent major options for treatment of metastatic breast cancer. Alternatively, chronic administration of agonistic analogues of luteinizing hormone-releasing hormone (LHRH) causes regression of mammary tumours in experimental animals, and such treatment has shown promise in a small series of premenopausal women with advanced breast cancer. It has been assumed that these results were achieved by suppressing the pituitary-ovarian axis, as the treatment causes a reduction in circulating levels of gonadal steroids similar to that produced by castration. However, LHRH agonists can exert major effects on tissues other than the pituitary in animals and in the human. Such findings, coupled with reports of LHRH in human breast milk and immunohistochemical evidence for the presence of LHRH-like activity in some human breast tumours, prompted us to test whether LHRH agonists could have direct antitumour effects. We now report major direct effects of LHRH and its agonists on the growth of breast tumour cells in culture.     

Interleukins 4 and 5 control expression of IL-2 receptor on murine B cells through independent induction of its two chains

Resting B cells express few, if any, receptors for interleukin-2 (IL-2), whereas activated B cells can express receptors for and respond to IL-2. IL-2 receptors can exist on the cell surface in three different forms; the complete high-affinity receptor, a heterodimer consisting of a chain of relative molecular mass (Mr) 70-75,000 (70-75K) and a chain of Mr 55K; the 70-75K chain alone, with intermediate affinity for IL-2; or the 55K chain alone, with low affinity for IL-2. We have previously reported that IL-5-stimulated B cells are induced to express the 55K chain. We report here evidence for the differential regulation of the expression of the two chains, namely that IL-4 and IL-5 can independently induce expression of the 70-75K and 55K chains respectively on murine B cells. As expected, cells stimulated to express the 55K chain alone are unresponsive to IL-2, whereas cells stimulated to express either the 70-75K chain or the 70-75/55K heterodimer respond to IL-2, at a high and low ligand concentration respectively, with a marked increase in proliferation. This orchestration of receptor expression and factor responsiveness may represent a novel activation pathway for B cells, where the two chains of a compound receptor are shown to be independently regulated.     

基于S3C44B0X嵌入式处理器的飞行控制计算机系统设计

根据无人机飞行控制系统小型化、低功耗、实时性好的要求,介绍了一种基于嵌入式处理器S3C44B0X和实时操作系统的飞行控制计算机的设计方案,给出了系统的硬件结构和设计要点,并就采用实时操作系统的控制软件的任务和运行流程进行了说明.该方案在保证系统性能同时,缩小了系统规模,提高了系统可靠性,简化了软件设计的复杂度,为同类产品的设计提供了新的思路.     

Transformation of NIH 3T3 cells by a human c-sis cDNA clone

The mechanism of leukaemogenic transformation by human T-cell leukaemia/lymphoma virus (HTLV), a retrovirus implicated in the aetiology of certain adult T-cell leukaemias and lymphomas, is unknown but is conceivably associated with the expression of the cellular analogues of retroviral oncogenes. The HUT-102 cell line, derived from a cutaneous T-cell lymphoma and infected with HTLV, expresses several cellular oncogenes. It is unusual among haemopoietic cell lines in that one of these is c-sis, the gene from which the oncogene v-sis of the simian sarcoma virus was derived, and perhaps the gene for platelet-derived growth factor (PDGF). To explore the possible role of c-sis expression in HTLV-induced disease, we have obtained cDNA clones of c-sis from HUT-102 cells. Here we describe two such clones and report that one of them transforms NIH-3T3 cells. This is the first example of transformation of NIH-3T3 cells by a human onc gene other than c-ras or Blym, as well as the first demonstration of transformation by a human cDNA clone.     

A camelid antibody fragment inhibits the formation of amyloid fibrils by human lysozyme

Amyloid diseases are characterized by an aberrant assembly of a specific protein or protein fragment into fibrils and plaques that are deposited in various organs and tissues, often with serious pathological consequences. Non-neuropathic systemic amyloidosis is associated with single point mutations in the gene coding for human lysozyme. Here we report that a single-domain fragment of a camelid antibody raised against wild-type human lysozyme inhibits the in vitro aggregation of its amyloidogenic variant, D67H. Our structural studies reveal that the epitope includes neither the site of mutation nor most residues in the region of the protein structure that is destabilized by the mutation. Instead, the binding of the antibody fragment achieves its effect by restoring the structural cooperativity characteristic of the wild-type protein. This appears to occur at least in part through the transmission of long-range conformational effects to the interface between the two structural domains of the protein. Thus, reducing the ability of an amyloidogenic protein to form partly unfolded species can be an effective method of preventing its aggregation, suggesting approaches to the rational design of therapeutic agents directed against protein deposition diseases.     

有丝分裂原体活化成人外周血自然杀伤细胞CD69表达的研究

目的 :利用自然杀伤细胞 (NK)的早期活化标记CD69的表达探讨NK细胞体外活化的规律 ,促进这类细胞的临床应用 方法 :用Ficoll-Hypaque梯度离心法分离出正常成人外周血单个核细胞 (PBMC) ,分别在两种不同的有丝分裂原 ,植物血凝素 (PHA ,2 0 μg/mL)和佛波醇酯 (PDB ,10 - 7mol/L)存在的条件下进行培养 ,于 0、2、12、2 4h收获细胞后进行双色免疫荧光标记 ,以流式细胞术对NK细胞的CD69分子表达情况进行分析 结果 :NK细胞在PHA、PDB刺激 2h后CD69的表达明显上升 ,而且随时间的延长CD69的表达率逐渐增加 ,2 4h分别达到 ( 84 .96± 9.2 4 ) %、( 91 85± 2 .94 ) % ;PDB刺激组CD69的表达率在不同的时间点均比PHA组高 结论 :体外条件下 ,PHA、PDB均能快速上调NK细胞CD69表达 ,而且PDB( 10 - 7mol/L)作用明显强于PHA( 2 0 μg/mL)     

Tumorigenic transformation of mammalian cells induced by a normal human gene homologous to the oncogene of Harvey murine sarcoma virus

A normal human gene homologous to the p21 ras oncogene of Harvey murine sarcoma virus induced oncogenic transformation and high p21 ras levels in murine fibroblasts when this gene was ligated to a control element (the long terminal repeat) from a murine or feline retrovirus. These results indicate that high levels of a gene product encoded by a normal human oncogene can induce tumorigenic transformation.     

The third component of complement (C3) is responsible for the intracellular survival of Leishmania major

Leishmania are obligate intracellular parasites of mononuclear phagocytes. We and others have shown that the promastigote form of all species of leishmania activates complement from non-immune serum and that this activation can result in parasite lysis. This work, as well as earlier in vivo studies, suggested that complement is an important component of host defence against leishmaniasis. We now present evidence that parasite complement fixation, in addition to increasing parasite phagocytosis, is required for the intracellular survival of leishmania in macrophages. We specifically show a strong correlation between parasite C3 fixation and intracellular survival. We attribute this survival, in part, to a decrease in the magnitude of the macrophage respiratory burst which is triggered by complement-coated, as opposed to uncoated, parasites.     

Identification of the human analogue of a regulator that induces differentiation in murine leukaemic cells

We have recently purified murine granulocyte colony-stimulating factor (G-CSF), a regulatory glycoprotein which stimulates granulocyte colony formation from committed murine precursor cells in semi-solid agar cultures. G-CSF is one of a family of colony-stimulating factors that regulate the growth and differentiation of granulocytes and macrophages. While the other murine CSFs (granulocyte-macrophage (GM)-CSF, macrophage (M)-CSF and multi-CSF) show little or no differentiation-inducing activity on murine myelomonocytic leukaemia cell lines, G-CSF (or MGI-2(6)) is able to induce the production of terminally differentiated cells from WEHI-3B and other myeloid leukaemia cell lines. More importantly, G-CSF-containing materials suppress the self-renewal of myeloid leukaemia stem cells in vitro and the leukaemogenicity of treated myeloid leukaemic cells in vivo. It is important to identify the human analogue of murine G-CSF so that its effectiveness on human myeloid leukaemia cells can be assessed. Here we show that an analogue of G-CSF does exist among the CSFs produced by human cells and that the murine and human molecules show almost complete biological and receptor-binding cross-reactivities to normal and leukaemic murine or human cells. The human G-CSF analogue is identified as a species of CSF that we have previously described as CSF-beta.     

Stimulation of multipotential, erythroid and other murine haematopoietic progenitor cells by adherent cell lines in the absence of detectable multi-CSF (IL-3)

It is well established that murine multipotential and committed erythroid progenitor cells require the presence of a glycoprotein, termed multi-CSF (multi-colony-stimulating factor, IL-3) for clonal proliferation and differentiation in vitro. The initial proliferation of these cells can also be stimulated by two other glycoproteins, granulocyte-macrophage CSF (GM-CSF) and granulocyte CSF (G-CSF), although continued proliferation and differentiation requires the subsequent presence of multi-CSF. Here we report the stimulation of multipotential, erythroid and other haematopoietic progenitor cells by a number of adherent cell lines including a cloned bone marrow cell line (B.Ad). The positive cell lines, as feeder layers, exhibit colony-stimulating, erythropoietin-like and burst-promoting (BPA) activities. Optimal erythropoietic stimulation by the B.Ad line requires close cell-cell contact. The cell lines also support the in vitro clonal growth of multipotential colony-forming cells and progenitors of six other haematopoietic lineages. The biological activities observed seem not to be mediated by known multipotential or erythroid colony-stimulating factors (multi-CSF, IL-3, MCGF, HCGF, PSF, BPA).