Search PubMed⌕ Search

Biomedical subjects

M J Selby

Publications and source records attributed to M J Selby.

35 records · Page 2Linked to original sources
PubMed1993

Expression, identification and subcellular localization of the proteins encoded by the hepatitis C viral genome.

We have expressed the full-length coding region and selected domains of the hepatitis C virus (HCV) cDNA in mammalian cells by transfection. Using HCV antibody-positive human sera and monospecific antibodies the proteins encoded by the putative structural and non-structural regions of the open reading frame of HCV were identified as core (p22), E1 (gp32-35), E2 (gp68-72), NS2 (p23), NS3 (p72), NS4a and b (p10 and p27) and NS5a and b (p56 and p70). We have also defined the subcellular localizations of the HCV proteins using indirect immunofluorescence assays.

Animals↗
PubMed1993

Measurement of hostility, anger, and depression in depressed and nondepressed subjects.

This study examined the relationship between hostility and depression in depressed and nondepressed subjects as well as the reliability and validity of several measures of anger, hostility and depression. Sixty-nine subjects were evaluated for depression using the Hamilton Rating Scale for Depression (HRSD; Hamilton, 1960). These subjects were then administered the Beck Depression Inventory (BDI; Beck, Ward, Mendelson, Mock, & Ergaugh, 1961), Buss-Durkee Hostility Inventory (BDHI; Buss & Durkee, 1957), Hostility and Direction of Hostility Questionnaire (HDHQ; Foulds, Caine, & Creasy, 1960) and the State-Trait Anger Scale (STAS; Spielberger, Jacobs, Russell, & Crane, 1983). Results showed the BDI, STAS-TRAIT, HDHQ, and BDHI to have good temporal stability. Support was found for the convergent validity of all measures of depression, hostility, and anger. Limited discriminant validity was found between measures of anger and hostility and measures of depression. This latter finding was interpreted as lending support for the relationship between hostility and depression rather than as an indication of limited construct validity for the measures. Intercorrelations among hostility, anger, and depression scales offer some support for the hypothesis that depression is linked most strongly with attitudinal versus motoric forms of hostility. However, normative data suggests that both forms of hostility increase with severity of depression. Clinical implications and directions for further research are discussed.

Adult↗
PubMed1991

Human immunodeficiency virus type 1 Tat does not transactivate mature trans-acting responsive region RNA species in the nucleus or cytoplasm of primate cells.

Human immunodeficiency virus (HIV)-encoded transactivator Tat is essential for viral gene expression and replication. By interacting with a nascent RNA stem-loop called the trans-acting responsive region (TAR). Tat increases rates of initiation and/or elongation of HIV transcription. Several reports have also suggested that Tat has additional effects on mature HIV RNA species including modification of primary transcripts in the nucleus and their increased translation in the cytoplasm. These posttranscriptional effects are most pronounced in the Xenopus oocyte. To investigate directly whether Tat has similar effects on viral transcripts in cells that are permissive for HIV replication, we cotransfected and microinjected human and monkey cells with Tat and TAR in the form of DNA or RNA. Whereas Tat transactivated TAR DNA targets, it did not transactivate TAR RNA targets in the nucleus of microinjected cells or in the cytoplasm of transfected cells. We conclude that in cells permissive for viral replication, Tat exerts its effect primarily at the level of HIV transcription.

Animals↗
PubMed1990

Trans-activation by HIV-1 Tat via a heterologous RNA binding protein.

The HIV-1 trans-activator Tat increases levels of viral gene expression and replication. The target for Tat is an RNA stem-loop called TAR, located at the 5' end of all viral transcripts. To study the mechanism of action and map functional domains of Tat, we fused Tat to the coat protein of bacteriophage MS2, an RNA binding protein. TAR in the HIV-1 LTR was replaced by the operator, the RNA target of the coat protein. The hybrid Tat-coat protein trans-activated HIV-1 LTRs containing either TAR or operator sequences. Mutations in the operator that weaken binding of the coat protein in vitro led to decreased levels of trans-activation in vivo. Deletions in Tat within the hybrid Tat-coat protein identified activation and RNA binding domains of Tat. These experiments suggest that trans-activation by Tat can occur independently of TAR RNA and DNA binding proteins and that Tat exerts its effects on HIV-1 transcription by directly interacting with the TAR RNA stem-loop.

Amino Acid Sequence↗
PubMed1989

Structure, sequence, and position of the stem-loop in tar determine transcriptional elongation by tat through the HIV-1 long terminal repeat.

The human immunodeficiency virus (HIV-1)-encoded trans-activator (tat) increases HIV gene expression and replication. Previously, we demonstrated that tat facilitates elongation of transcription through the HIV-1 long terminal repeat (LTR) and that short transcripts corresponding to prematurely terminated RNA are released and accumulate in the absence of tat. Here, using a transient expression assay, we tested clustered and compensatory mutations, as well as 3' deletions, in the trans-acting responsive region (tar) and observed that the primary sequence in the loop and secondary structure in the stem of the stem-loop in tar are required for trans-activation by tat. Insertions in the 5' region of tar revealed that tar must be near the site of HIV-1 initiation of transcription for trans-activation by tat. Deletions (3') and an insertion in tar demonstrated that an intact stem-loop is required for the recovery of prematurely terminated transcripts. Short and full-length transcripts were observed also with HIV type 2 (HIV-2) in the absence and presence of tat, respectively. We conclude that an intact stem-loop in tar is essential for trans-activation by tat and that initiation of transcription by HIV-1 promoter factors and elongation of transcription by tat are coupled.

Chloramphenicol O-Acetyltransferase↗
PubMed1988

Processing of the native nerve growth factor precursor to form biologically active nerve growth factor.

In the mouse submaxillary gland beta nerve growth factor (beta-NGF) forms a complex with two members of the kallikrein family of serine proteases, termed the alpha- and gamma-subunits of NGF. We demonstrate that the beta-NGF precursor produced in mammalian cells via a recombinant vaccinia virus can be cleaved by stoichiometric quantities of the gamma-subunit to produce beta-NGF. Trypsin in catalytic quantities also produces native beta-NGF. Proper cleavage depends critically on the conformation of the precursor. beta-NGF has at least 10-fold more biological activity than its precursor.

Animals↗
PubMed1988

Processing and secretion of nerve growth factor: expression in mammalian cells with a vaccinia virus vector.

To study posttranslational mechanisms for the control of nerve growth factor (NGF), we used a recombinant vaccinia virus vector to independently express the two major NGF transcripts in a variety of mammalian cell lines. The two major transcripts contain NGF (12.5 kilodaltons [kDa]) at the C-terminus and differ by alternative splicing of an N-terminal exon, so that the large precursor (34 kDa) had 67 amino acids upstream of an internal signal peptide and the smaller precursor (27 kDa) had this signal peptide at its N-terminus. In L929 cells, expression of either NGF transcript with the vaccinia virus vector gave rise to an apparently identical intracellular 35-kDa glycosylated precursor formed by cleavage of the primary gene product after the signal peptide. These cells also secreted biologically active NGF. To determine whether NGF processing is restricted by cell type, we infected a variety of mammalian cell lines with both recombinant viruses; all accumulated the same 35-kDa precursor and secreted NGF. Thus, many types of cells have the machinery to process and secrete NGF. However, NGF accumulated intracellularly (presumably in secretory granules) in cells with a regulated pathway of secretion (e.g., AtT-20 and HIT cells). In these cells, a membrane-permeable cyclic AMP analog, 8-bromo-cyclic AMP, stimulated NGF secretion. This suggests a mechanism for the regulation of NGF levels in which specific secretagogues, e.g., neurotransmitters, control NGF secretion.

Animals↗
PubMed1987

Cobra nerve growth factor: structure and evolutionary comparison.

We have cloned and sequenced an NGF cDNA from the cobra venom gland. The structure of the predicted cobra precursor resembles that of the mouse prohormone, with a highly conserved mature NGF protein at the C-terminus. In the non-NGF moiety, a putative signal peptide and two sets of basic residues presumably reflecting cleavage sites that are more conserved, while large interstitial regions are poorly conserved. This moiety may be involved in defining the folding of the precursor for subsequent proteolytic maturation and/or encode a bioactive polypeptide(s). Primer extension analysis indicates a single NGF transcript in the cobra venom gland.

Amino Acid Sequence↗
PubMed1987

Mouse nerve growth factor gene: structure and expression.

The organization and biologically significant sequences of the entire mouse nerve growth factor (NGF) gene have been determined. The gene spans 45 kilobases and contains several small 5' exons. Transcription of the gene results in four different mRNA species, which can be accounted for by alternative splicing and independent initiation from two promoters. These transcripts encode proteins which have divergent N termini and the NGF moiety at their C termini. The levels of the various NGF transcripts have been determined in different tissues and throughout postnatal development. We have also examined the expression of these transcripts in the brain in response to specific early sensory deprivation. The results suggest that the expression of NGF mRNA during postnatal development is regulated independently of the formation of complex neural networks.

Age Factors↗
PubMed1984

Analysis of a major human chorionic somatomammotropin gene. Evidence for two functional promoter elements.

The sequence of one of the two major expressed human chorionic somatomammotropin genes (hCS-1) was determined. The hCS-1 gene and the human growth hormone gene (hGH-1) share 92% nucleotide sequence homology in their 5'- and 3'-flanking regions, introns and exons. This finding, in addition to the existence of multiple closely linked hGH and hCS genes, suggests that these genes are evolving by concerted mechanisms. S1 nuclease, hybridization, and primer extension analysis of placental poly(A+) RNA demonstrated the presence of two functional initiation sites within the hCS-1 and/or the hCS-2 gene(s). The majority (about 95%) of the transcripts initiate 30 nucleotides downstream from the TATAAA sequence, and about 5% of the transcripts initiate 30 nucleotides downstream from a CATAAA sequence located 55 nucleotides 5' to the TATAAA sequence. The presence of two functional promoter elements as well as direct repeated sequences flanking the TATAAA sequence and exon I of the hCS genes are consistent with the hypothesis (Cooke, N. E., and Baxter, J. D. (1982) Nature (Lond.) 297, 603-606) that an important regulatory element may have been inserted into the gene in a separate evolutionary event. An analysis of other direct repeats, internal homology, and homology between other growth hormone and chorionic somatomammotropin genes offers a more extensive conceptualization of how this gene family evolved.

Amino Acid Sequence↗
PubMed1984

Assessment of violence potential using measures of anger, hostility, and social desirability.

The assessment of violence potential was studied using the following scales: The Novaco Anger Inventory, the Buss-Durkee Hostility Inventory, the MMPI Hostility Control Scale (Hc), the MMPI Overt Hostility Scale (Ho), and the Marlowe-Crowne Social Desirability Scale. The five measures were evaluated for their ability to discriminate between violent and nonviolent criminals, and between criminal and normal population samples. Normative data was collected for 204 adult male felons. A correlation matrix presents interrelationships among the five scales. A comparison of mean scale scores between violent and nonviolent groups resulted in a significant discrimination in the expected direction for all but the Hc scale. A discriminant analysis procedure applied to individual items from the Novaco Anger Inventory resulted in the selection of 25 variables which identified violence prone individuals with 90% accuracy. Clinical implications are noted and recommendations for future research are made.

Anger↗
PubMed1980

Evaluation of a rapid method for the quantitative estimation of coliforms in meat by impedimetric procedures.

A 24-h instrumental procedure is described for the quantitative estimation of coliforms in ground meat. The method is simple and rapid, and it requires but a single sample dilution and four replicates. The data are recorded automatically and can be used to estimate coliforms in the range of 100 to 10,000 organisms per g. The procedure is an impedance detection time (IDT) method using a new medium, tested against 131 stock cultures, that markedly enhances the impedance response of gram-negative organisms, and it is selective for coliforms. Seventy samples of ground beef were analyzed for coliforms by the IDT method and the conventional three-dilution, two-step most-probable-number test tube procedure. Seventy-nine percent of the impedimetric estimates fell within the 95% confidence limits of the most-probable-number values. This corresponds to the criteria used to evaluate other coliform tests, with the added advantage of a single dilution and more rapid results.

Animals↗
PubMedDate not supplied

Differential RNA splicing predicts two distinct nerve growth factor precursors.

Nerve growth factor (NGF) has a crucial role in the development of sensory and sympathetic neurones. However, although it can affect other neural cell types under certain experimental conditions, no biological role has been convincingly demonstrated elsewhere in the nervous system. The 5' end of the mouse NGF gene contains several relatively short exons. The NGF messenger RNA contains two in-frame initiator methionine codons; the second precedes the signal peptide sequence. Studies of the translation of other eukaryotic mRNAs indicate that the first AUG is preferred, suggesting that the signal for secretion might be ambiguous. We have analysed the NGF mRNA species from various cell types, some of which (clonal myoblast and fibroblast cell lines) are known to secrete NGF, to search for different NGF transcripts. One pathway of RNA splicing generates the transcript already described from a submaxillary gland complementary DNA clone. We demonstrate here that there is another splicing pathway, leading to a shorter transcript that lacks the second exon. This short transcript is the major form in most other mouse tissues and in the tissues of several other species, but both transcripts are usually present. In the short transcript, the initiator methionine is immediately upstream from a signal peptide-like sequence whereas in the long transcript the first methionine is 62 amino acids upstream from the signal peptide-like sequences. This may result in a different cellular localization of the NGF or alter the biological activity of the NGF precursor.

Animals↗