Direct effect of glucose on the preproinsulin mRNA level in isolated pancreatic islets

The effects of glucose on the preproinsulin mRNA level and the rate of (pro)insulin biosynthesis were examined in isolated mouse pancreatic islets. Relative concentrations of preproinsulin mRNA were quantitated by a RNA-dot hybridization procedure. The level of preproinsulin mRNA in islets incubated for up to 7 days at 20 mM glucose remained constant. In islets incubated at 3.3 mM glucose the preproinsulin mRNA level decreased and was after 24 h reduced to one tenth of the level at 20 mM glucose. Subsequent incubation at 20 mM glucose completely restored the preproinsulin mRNA level but only after 3 days of culture, while the insulin release was restored within 24 h. The insulin-biosynthetic activity of the islets was correlated to the variation in the level of the preproinsulin mRNA. These results suggest that glucose does have a direct influence on the level of preproinsulin mRNA and that the rate of (pro)insulin biosynthesis is limited by the level of the preproinsulin mRNA.     

斑点酶免疫实验检测流行性出血热抗体方法的研究

本文应用斑点酶免疫试验(DEIA),检测流行性出血热病人血清42份,其结果与间接免疫荧光(IFA)进行了比较,符合率100％,其DEIA几何干均滴度为1:880,IFA为1:580,同类风湿因子阳性血清[RF(+)]无交叉反应,证明本方法具有较高的敏感性和特异性,本文还对不同方法处理组织内源酶的效果和不同阻断剂的阻断效果进行了比较。试验结果表明本法不但敏感、特异,而且简单、快速、安全、经济、易于推广。     

Synthesis and assembly of the synaptic cleft protein S-laminin by cultured cells.

S-laminin, a homologue of the B1 chain of laminin, is concentrated in a subset of basal laminae (BLs), including the BL at the skeletal neuromuscular junction and bears an adhesive site for motoneuron-like cells. Here, we have begun to characterize the native form of the protein. We show that several muscle- and glia-like cell lines synthesize and secrete S-laminin as well as the A, B1, and B2 subunits of the conventional laminin trimer. Experiments using subunit-specific antibodies showed that S-laminin is complexed with the A and B2 subunits of laminin but not with B1, suggesting that S-laminin replaces B1 to form a novel laminin-like trimer. Comparison of material precipitated by different antibodies provided evidence for two immunochemically distinct forms of S-laminin, both of which associate with B2 and A-like subunits. Analysis of tunicamycin-treated cells indicated that N-linked glycosylation is required neither for the selective association of S-laminin with B2 and A subunits nor for the distinction between two forms of S-laminin. Finally, a full-length S-laminin cDNA was constructed and transfected into muscle and non-muscle cells. S-laminin was detected intracellularly in both cell types, in extracellular matrix of muscle cells, and in two immunochemically distinct forms. Thus, the cDNA contains sufficient information to permit assembly, secretion, and post-translational modification of S-laminin.     

Differences in the In Vitro and In Vivo 5-Hydroxytryptamine Extraction Performance Among Three Common Microdialysis Membranes

The present study summarizes the results of an in vitro and in vivo comparison of the apparent 5-hydroxytryptamine (5-HT), 5-hydroxyindoleacetic acid, and 3,4-dihydroxyphenylacetic acid dialysis performance of three types of membrane frequently used in intracerebral microdialysis experiments. The dialysis fiber types examined were a regenerated cellulose Cuprophan (GF), a proprietary polycarbonate ether (CMA), and a polyacrylonitrile/sodium methallylsulfonate copolymer (HOSPAL). The experiments unexpectedly revealed that the HOSPAL membrane-equipped probes displayed clearly aberrant 5-HT diffusion dynamics compared with GF and CMA probes, demonstrable not only in vitro, but also in in vivo experiments. In vitro, the GF and CMA membrane-equipped probes exhibited maximum relative recovery for 5-HT already in the first 20-min sample, whereas the 5-HT recovery of HOSPAL probes increased in a very slow and protracted manner over a period of a little less than 2 h. The GF and CMA probes further displayed an immediate washout of 5-HT when the probes were subsequently transferred to artificial CSF only-containing medium (no 5-HT), whereas approximately 2 h was required to yield near-total extinction of dialysate 5-HT with the standard HOSPAL probes. In vivo, the rat ventral hippocampal dialysate 5-HT output responses to K+ (100 mM) infusion, to Ca2+ omission, and to systemic 8-hydroxy-2-(di-n-propylamino)tetralin injection were all markedly retarded and blunted when HOSPAL instead of GF membrane-equipped probes were used. However, the 5-hydroxyindoleacetic acid and 3,4-dihydroxyphenylacetic acid extraction in vitro and in vivo were comparable using either of the membrane types.(ABSTRACT TRUNCATED AT 250 WORDS)     

Control of experimental autoimmune uveoretinitis by low dose T cell vaccination.

Autoimmune T lymphocytes can be used under appropriate conditions to induce resistance to the specific autoimmune disease that they usually produce. This practice, termed T cell vaccination, was found to be effective with the injection of a low (subpathogenic) number of autoaggressive T line lymphocytes. We report here that T cell vaccination produced marked resistance to the expression of experimental autoimmune uveoretinitis (EAU) in Lewis rats. In addition, vaccination led to the appearance of lymphoid cells in the vaccinated rats that demonstrated proliferative responses against idiotypic and ergotypic specificities of the injected T cells. This is the first report demonstrating the effector T lymphocytes specific for ocular antigens may be used as agents to modulate immunopathogenic responses responsible for EAU.     

Genetics and polymorphism of a duplicated malate dehydrogenase (MDH) locus in the grasshopperOxya japonica japonica (Orthoptera:Acrididae:Oxyinae)

A biochemical genetic study of the enzyme malate dehydrogenase (MDH) was conducted in the grasshopperOxya j. japonica. Analysis of MDH electrophoretic variation in this species of grasshopper shows that one of the two autosomal loci for MDH in grasshoppers, the Mdh-2 locus, controlling the anodal set of MDH isozymes, is duplicated. Results of breeding studies confirm this and the observed polymorphism at theMdh-2 locus in the two populations ofOxya j. japonica studied can be attributed to three forms of linked alleles at the duplicated locus in equilibrium in both populations. In this respect, all individuals of this species possess heterozygous allelic combinations at the duplicatedMdh-2 locus, which may account for the spread of the duplicated locus in the populations of this species of grasshopper.This research was supported by a grant (Vote F) from the University of Malaya, Kuala Lumpur.     

Extrachromosomal human immunodeficiency virus type-1 DNA can initiate a spreading infection of HL-60 cells

In this report, we describe a human immunodeficiency virus type-1 (HIV-1)-infected promyelocytic cell line, OM, derived from HL-60 cells. Although the OM cell line was biologically cloned twice, the pattern of HIV-1 expression during culture appeared analogous to a classical acute spreading infection and was inhibited by both azidothymidine and recombinant soluble CD4 treatment. The number of OM cells actually expressing HIV-1 at the beginning of culture was 0%, reached a peak of nearly 100% at 6 weeks, and then fell to less than 10% HIV-1+ cells by 10 weeks. Clonal analysis of the surviving cells verified that stable HIV-1+ OM cells resulted from the spreading infection. Southern analysis confirmed the transmission of HIV-1 through these OM cultures and the occurrence of stable clones which resulted. The initial percentage of OM cells actually harboring the HIV-1 genome was less than 0.1%, indicating nonfaithful transmission of an unintegrated HIV-1 genome during clonal expansion. These results demonstrate that extrachromosomal HIV-1 DNA can contribute to the spread of HIV-1 infection and give rise to cells which have stably integrated HIV-1 provirus.