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Biomedical subjects

S M Ruben

Publications and source records attributed to S M Ruben.

47 records · Page 3Linked to original sources
PubMed1991

Isolation of a rel-related human cDNA that potentially encodes the 65-kD subunit of NF-kappa B.

A DNA probe that spanned a domain conserved among the proto-oncogene c-rel, the Drosophila morphogen dorsal, and the p50 DNA binding subunit of NF-kappa B was generated from Jurkat T cell complementary DNA with the polymerase chain reaction (PCR) and degenerate oligonucleotides. This probe was used to identify a rel-related complementary DNA that hybridized to a 2.6-kilobase messenger RNA present in human T and B lymphocytes. In vitro transcription and translation of the complementary DNA resulted in the synthesis of a protein with an apparent molecular size of 65 kilodaltons (kD). The translated protein showed weak DNA binding with a specificity for the kappa B binding motif. This protein-DNA complex comigrated with the complex obtained with the purified human p65 NF-kappa B subunit and binding was inhibited by I kappa B-alpha and -beta proteins. In addition, the 65-kD protein associated with the p50 subunit of NF-kappa B and the kappa B probe to form a complex with the same electrophoretic mobility as the NF-kappa B-DNA complex. Therefore the rel-related 65-kD protein may represent the p65 subunit of the active NF-kappa B transcription factor complex.

Amino Acid Sequence↗
PubMed1990

Expression of the HTLV-I tax transactivator in yeast: correlation between phenotypic alterations and tax function in higher eukaryotes.

The transcriptional activator protein (Tax) from human T-cell leukemia virus type 1 was expressed in yeast using several different promoters in several strains: In all instances, expression of Tax resulted in very strong aggregation of the yeast cells. This phenotype appears to be identical by all criteria tested to the flocculation phenotype of the dominant mutation flo 1. Of most significance, mutations in Tax that affect transactivation of the IL-2R alpha regulatory sequences, but retain their ability to activate the viral long terminal repeat also fail to yield the aggregation phenotype. Based on these findings, expression of Tax in yeast may prove to be a simple primordial system for examining the regulatory mechanisms and cellular functions involved in regulation of gene expression.

Gene Products, tax↗
PubMed1990

Suppression of signals required for activation of transcription factor NF-kappa B in cells constitutively expressing the HTLV-I Tax protein.

Transient short-term expression of the Tax protein of human T-cell leukemia virus type-I (HTLV-I) leads to activation of the pleiotropic transcription factor NF-kappa B. Consistent with findings obtained with transient expression assays, we observed marked accumulation of the transcription factor NF-kappa B in the nucleus of Namalwa B lymphoid cells, which constitutively express Tax. In contrast, NF-kappa B activity was not detected in the nucleus following long-term expression of Tax in Jurkat T lymphocytes. The ability of both mitogens and cytokines to activate NF-kappa B was also blocked in Jurkat cells constitutively expressing Tax. However, the activation of other mitogen-inducible transcription factors, such as Fos and Jun, was unaffected. Thus, depending on the cellular environment, the short- and long-term effects of Tax expression can be quite different. Consequently, one function of Tax in cells infected with HTLV-I might involve cell-type-specific suppression, as opposed to activation, of distinct signal pathways. The cells lines described here should be useful for the delineation of signaling pathways utilized in the selective regulation of gene expression.

B-Lymphocytes↗
PubMed1989

Cyclizine abuse among a group of opiate dependents receiving methadone.

Twenty opiate dependents receiving long-term prescriptions of oral methadone, were identified as being habitual abusers of the anti-emetic drug cyclizine. A semi-structured interview elicited the dosage of cyclizine used, its effects, the reasons for starting and persisting with abuse of cyclizine and the attitudes of the patients to it. Cyclizine was taken in large doses intravenously with methadone. The effects initially were of intense stimulation, often with hallucinations, sometimes with aggressive behaviour, and occasionally with epileptic fits. Subsequent depressive mood changes occurred often accompanied by a craving for cyclizine. Tolerance to the drug occurred but no clear cut withdrawal syndrome is apparent. It seems that dependence upon cyclizine occurs. The significance of these findings for doctors, pharmacists and for drug treatment units is discussed. The paucity of information on the pharmacology and pharmacokinetics is noted.

Adult↗
PubMed1989

Activation of NF-kappa B by the HTLV-I trans-activator protein Tax requires an additional factor present in lymphoid cells.

The Tax protein of human T-cell leukemia virus is a potent transcriptional activator of viral and cellular genes, including the genes for interleukin 2 and interleukin 2 receptor alpha chain (IL2R alpha). The NF-kappa B protein has been implicated in Tax-mediated activation of IL2R alpha gene expression. We show that activation of NF-kappa B by Tax is an indirect process that requires prior activation of a preexistent factor that is present in lymphoid cells. Deletion mutagenesis revealed that the carboxyl-terminal acidic region of Tax is required for activation of IL2R alpha-directed gene expression but dispensable for activation of the long terminal repeat (LTR). Our findings suggest that activation of viral and cellular gene expression by Tax is achieved through a cascade of events that involves multiple protein-protein associations and that the specificity of these associations is conferred through different domains of the Tax protein.

B-Lymphocytes↗
PubMed1989

Structural and functional characterization of the human immunodeficiency virus rev protein.

Expression of the human immunodeficiency virus (HIV) rev protein is required for expression of virus structural proteins. Site-directed mutagenesis was used to localize regions important for Rev function. We found that proteins with single amino acid substitution mutations concentrated within the amino termini and midportion of Rev were for the most part nonfunctional. Indirect immunofluorescence revealed that Rev was localized predominantly in the nucleolus. However, a deletion mutant that lacked the basic stretch of amino acids comprising residues Arg-Arg-Arg-Arg-Trp accumulated in the cytoplasm and was no longer functional. Consistent with this observation, a beta-galactosidase fusion protein containing this basic rich peptide at its amino termini was targeted to the nucleus. These observations indicate that the HIV rev protein has a distinct nuclear localization sequence and suggest that Rev-mediated regulation of gene expression involves nuclear events.

Amino Acid Sequence↗
PubMed1988

Suppression of the Escherichia coli ssb-1 mutation by an allele of groEL.

A series of spontaneous suppressors to the temperature-sensitive phenotype of the single-stranded DNA-binding protein mutation ssb-1 were isolated. A genomic library of EcoRI fragments from one of these suppressor strains was prepared by using pBR325 as the cloning vector. A 10.0-kilobase class of inserts was identified as carrying the ssb-1 gene itself. A second class of 8.3-kilobase inserts was shown to contain the groE region by (i) restriction analysis, (ii) Southern hybridization of the 8.3-kilobase insert to groE+ DNA, and (iii) identification of the gene products by similar migration on polyacrylamide gels. Subcloning demonstrated that an intact mutant groEL gene was necessary for suppression and that plasmids carrying the 8.3-kilobase insert could suppress mutants carrying groES- but not groEL- genes for phage lambda growth. The suppressor, designated as groEL411, was specific for the ssb-1 allele. In ssb-1 groEL411 cells, DNA synthesis stopped after a shift to 42.5 degrees C but rapidly recovered within minutes. The data suggest a direct interaction between the single-stranded DNA-binding protein and GroEL proteins in DNA replication.

Bacterial Proteins↗
PubMed1982

Influence of single-stranded DNA-binding protein on recA induction in Escherichia coli.

Two ssb mutants of Escherichia coli, which carry a lesion in the single-strand DNA-binding protein (SSB), are sensitive to UV-irradiation. We have investigated the influence of SSB on the "SOS" repair pathway by examining the levels of recA protein synthesis. These strains fail to induce normal levels of recA protein after treatment with nalidixic acid or ultraviolet light. The level of recA protein synthesis in wild-type cells is about three times greater than ssb cells. This deficiency in ssb mutants occurs in all strains and at all temperatures tested (30-41.5 degrees). In contrast, the ssb-1 mutation has no effect on temperature-induced recA induction in a recA441 (tif-1) strain. Cells carrying ssb+ plasmids and overproducing normal DNA-binding protein surprisingly are moderately UV-sensitive and have reduced levels of recA protein synthesis. Together these results establish that single-strand DNA-binding protein is involved in the induction of recA, and accounts, at least in part, for the UV sensitivity of ssb mutants. Three possible mechanisms to explain the role of SSB are discussed.

Bacterial Proteins↗
PubMedDate not supplied

Female sexual health problems in a drug dependency unit.

The Government of the United Kingdom has produced a strategic plan called the Health of the Nation aimed at achieving better health in key areas including a reduction in rates of unwanted pregnancies, sexually transmitted diseases and cervical cancer. Conventional health care systems fail some groups with special needs. This cross-sectional interview study was undertaken to determine the level and type of contraceptive use, and the attitudes of female opiate abusers to the use and availability of contraceptives and cytology services. The subjects were 201 opiate-dependent women enrolled in a methadone maintenance programme in a large drug dependency unit: 169 (84.5%) were sexually active and 65 (44.2%) of non-pregnant sexually active women did not use a contraceptive method. Thirty-six (43.9%) of those using a contraceptive were using condoms, with which the majority were dissatisfied. Sixty-one (30.3%) had never had a cervical cytology smear and of those who had, 21.4% reported an abnormal result. The contraceptive practices and uptake of cervical screening services by the women studied are inadequate, reflecting poor use of conventional health care services. In addition to providing information on safer sexual practices, particularly promotion of condom use, we suggest that drug dependency units should expand their role to provide educational and preventative services to include aspects of women's health.

Adolescent↗