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Biomedical subjects

P Robbins

Publications and source records attributed to P Robbins.

At least 73 records · Page 4Linked to original sources
PubMed1994

Cloning, sequence, and disruption of the Saccharomyces diastaticus DAR1 gene encoding a glycerol-3-phosphate dehydrogenase.

The Saccharomyces diastaticus DAR1 gene was cloned by complementation in an Escherichia coli strain auxogrophic for glycerol-3-phosphate. DAR1 encodes an NADH-dependent dihydroxyacetone phosphate reductase (sn-glycerol-3-phosphate dehydrogenase [G3PDase; EC 1.1.1.8]) homologous to several other eukaryotic G3PDases. DAR1 is distinct from GUT2, which encodes a glucose-repressed mitochondrial G3PDase, but is identical to GPD1 from S. cerevisiae, a close relative of S. diastaticus. The level of DAR1-encoded G3PDase was increased about threefold in a medium of high osmolarity. Disruption of DAR1 in a haploid S. cerevisiae was not lethal but led to a decrease in cytoplasmic NADH-dependent G3PDase activity, an increase in osmotic sensitivity, and a 25% reduction in glycerol secretion from cells grown anaerobically on glucose.

Amino Acid Sequence↗
PubMed1994

Hormone-regulated genes (pS2, PIP, FAS) in breast cancer and nontumoral mammary tissue.

Expression of the hormone-regulated genes, pS2, prolactin-inducible protein (PIP) and fatty acid synthetase (FAS), was investigated by Northern blotting in primary breast carcinoma, metastatic breast cancer in axillary lymph nodes, in uninvolved breast tissue from mastectomies and in normal lymph nodes. There were considerable differences in expression of the genes between the tissues. The proportion of tissues containing PIP-mRNA decreased from uninvolved breast tissue to primary breast carcinoma to metastatic carcinoma. The reverse applied to FAS-mRNA which was found more often in metastatic cancer than in primary cancer, and least frequently in uninvolved breast tissue. Yet another pattern was observed for pS2 expression. The highest proportion of tissues demonstrating gene expression was found in primary breast cancer with both metastatic tumor and uninvolved breast tissue expressing the gene less frequently. pS2-mRNA and PIP-mRNA could only rarely be detected in trace amounts in normal lymph nodes. In contrast, FAS-mRNA was present in about one third of normal lymph nodes. Only pS2-mRNA showed an association with estrogen and progesterone receptor status.

Blotting, Northern↗
PubMed1993

Expression of the pS2 gene in normal breast tissue.

pS2 expression in normal breast tissue removed for cosmetic reasons was significantly lower than in uninvolved breast tissues from mastectomies for breast carcinomas. It is speculated that the presence of the carcinoma, or factors related to its development, could be the reason for this difference.

Breast↗
PubMed1993

Biosynthesis of asparagine-linked oligosaccharides in Saccharomyces cerevisiae: the alg2 mutation.

In the yeast Saccharomyces cerevisiae, the alg2 mutation causes temperature-sensitive growth and abnormal accumulation of the lipid-linked oligosaccharide Man2GlcNAc2-PP-Dol (Jackson et al., Arch. Biochem. Biophys., 272, 203-209, 1989; Huffaker and Robbins, Proc. Natl. Acad. Sci. USA, 80, 7466-7470, 1983). A gene having the function and genomic location of ALG2 was cloned from libraries based on the multicopy plasmid YEp24 and on the centromere plasmid YCp50. Alg2 mutants transformed with plasmids containing ALG2 regained the capacity to grow and to synthesize lipid-linked oligosaccharides normally at the previously non-permissive temperature. ALG2 was essential for viability in haploid and diploid yeast. The ALG2 gene was transcribed into a single mRNA of 1.7 kb in size. The stability of ALG2 mRNA, assessed after thermal inactivation of RNA polymerase II in an rpb1-1 mutant (Herrick et al., Mol. Cell. Biol., 10, 2269-2284, 1990) was very low, with a t1/2 of < 5 min. The ALG2 transcript accumulation was growth dependent, and it was at least an order of magnitude lower in stationary phase cells compared to exponentially growing cells. The putative translation product of ALG2 contained a potential dolichol recognition domain similar to that found in all three glycosyltransferases of the lipid-linked pathway that have been sequenced.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1993

A mathematical model of the human ventilatory response to isocapnic hypoxia.

A mathematical model of the ventilatory response to a period of sustained isocapnic hypoxia in humans has been developed. After a step into hypoxia, there is an initial rapid increase in ventilation (on-transient) followed by a slow decline. At the relief of hypoxia, there is a rapid decrease in ventilation (off-transient); the magnitude of this off-transient is smaller than that of the on-transient. Previously, the asymmetry between the on- and off-transients has been dealt with by modeling the steps into and out of hypoxia separately. The current objective was to model the whole of the response by allowing the peripheral sensitivity to hypoxia to decline during the sustained exposure to hypoxia. The model was fitted to breath-by-breath data from 20-min periods of hypoxia (end-tidal oxygen 50 Torr) at two different levels of end-tidal carbon dioxide tension from five subjects. The model was able to describe the features of the ventilatory changes well, including the slow decline and the asymmetry.

Carbon Dioxide↗
PubMed1992

Efficient transfer and sustained high expression of the human glucocerebrosidase gene in mice and their functional macrophages following transplantation of bone marrow transduced by a retroviral vector.

A recombinant retroviral vector (MFG-GC) was used to study the efficiency of transduction of the human gene encoding glucocerebrosidase (GC; D-glucosyl-N-acylsphingosine glucohydrolase, EC 3.2.1.45), in mouse hematopoietic stem cells and expression in their progeny. Transfer of the GC gene to CFU-S (spleen cell colony-forming units) in primary and secondary recipients was virtually 100%. In mice 4-7 months after transplantation, highly efficient transfer of the human gene to bone marrow cells capable of long-term reconstitution was confirmed by detection of one or two copies per mouse genome in hematopoietic tissues and in cultures of pure macrophages. Expression of the human gene exceeded endogenous activity by several fold in primary and secondary CFU-S, tissues from long-term reconstituted mice, and explanted macrophages cultures. These studies are evidence of the feasibility of efficient transfer of the GC gene to hematopoietic stem cells and expression in their progeny for many months after reconstitution. The results of this study strengthen the rationale for gene therapy as a treatment for Gaucher disease.

Animals↗
PubMed1992

Direct repeat sequences are implicated in the regulation of two Streptomyces chitinase promoters that are subject to carbon catabolite control.

We report the identification and partial characterization of the promoters for two chitinase genes from Streptomyces plicatus. Chitinases are a family of enzymes made by Streptomyces and other soil microbes to digest chitin, an abundant source of carbon and nitrogen in the soil. The promoter regions of two chitinases were defined by using transcriptional fusions to the xylE reporter gene. Transcription was shown to be glucose-sensitive and chitin-dependent. Each promoter contains a putative RNA polymerase binding site with a recognition sequence very similar to that observed in many eubacterial vegetatively expressed genes. In both promoters, a pair of 12-base-pair direct repeat sequences overlap the putative RNA polymerase binding sites. Further analysis of one of the promoters revealed that a single-base change within the direct repeat sequences resulted in glucose-resistant, chitin-independent expression in vivo. In addition, the promoter region that includes the direct repeat sequences was shown to interact with a sequence-specific DNA binding factor in vitro. Similar direct repeat sequences are present in other chitinase genes recently characterized, and we suggest that these repeats may be involved in repression and induction for this entire class of catabolite-controlled genes.

Base Sequence↗
PubMed1992

Expression of the pS2 gene in breast tissues assessed by pS2-mRNA analysis and pS2-protein radioimmunoassay.

The expression of the pS2 gene in breast tissues was assessed by measuring pS2-protein using a radioimmunoassay, and by determining pS2-mRNA using Northern blotting. There was a good correlation between the two measurements, indicating that expression of the pS2 gene in breast tissues may be assessed by either method. Since radioimmunoassay is technically easier and more efficient than Northern blotting, radioimmunoassay will be the method of choice in routine applications.

Blotting, Northern↗
PubMed1992

HIV-1 protease cleaves actin during acute infection of human T-lymphocytes.

Actin, one of the most abundant proteins of the cell, is hydrolyzed by the human immunodeficiency virus type 1 (HIV-1) protease during acute infection of cultured human T lymphocytes. The actin fragments produced during the course of infection are identical to those obtained by recombinant HIV-1 protease digests of (1) a lysate from uninfected T lymphocytes and (2) globular actin itself. Hydrolysis by the HIV-1 protease of physiologically important host cellular proteins during infection may have important consequences relative to viral pathogenesis.

Actins↗
PubMed1989

Repression of the IgH enhancer in teratocarcinoma cells associated with a novel octamer factor.

Embryonal carcinoma (EC) cell lines are models for early cells in mouse embryogenesis. A 300-base pair fragment of the heavy chain enhancer was inactive in F9 EC cells, unlike in other nonlymphoid cells where it has significant activity. Alterations of the octamer motif increased enhancer activity. Nuclear extracts from F9 cells contained an octamer binding protein (NF-A3) that was unique to EC cells; the amount of NF-A3 decreased upon differentiation. It is proposed that NF-A3 represses specific regulatory sequences that contain the octamer motif. Thus, the same DNA sequence mediates either negative or positive transcriptional effects, depending on the cell type.

Animals↗
PubMed1987

Sex pheromone production and perception in European corn borer moths is determined by both autosomal and sex-linked genes.

Inheritance patterns for sex pheromone production in females, pheromone detection on male antennal olfactory receptor cells, and male pheromone behavioral responses were studied in pheromonally distinct populations of European corn borers from New York State. Gas chromatographic analyses of pheromone glands, single sensillum recordings, and flight tunnel behavioral analyses were carried out on progeny from reciprocal crosses, as well as on progeny from subsequent F(2) and maternal and paternal backcrosses. The data show that the production of the female pheromone blend primarily is controlled by a single autosomal factor, that pheromone-responding olfactory cells are controlled by another autosomal factor, and that behavioral response to pheromone is controlled by a sex-linked gene. F(1) males were found to possess olfactory receptor cells that give spike amplitudes to the two pheromone isomers that are intermediate to those of the high and low amplitude cells of the parent populations. Fifty-five percent of the F(1) males tested responded fully to pheromone sources ranging from the hybrid (E)-11-tetradecenyl acetate/(Z)-11-tetradecenyl acetate (E/Z) molar blend of 65:35 to the E/Z molar blend of 3:97 for the Z morph parents, but very few responded to the E/Z molar blend of 99:1 for the E morph parents. Data on the inheritance patterns support speculation that the Z morph is the ancestral and that the E morph is the derived European corn borer population.

Journal Article↗
PubMed1984

Venous pressures during simulated Bier's block.

Venous pressures in the forearm veins during the simulated performance of intravenous regional analgesia were measured. Pressures obtained equalled or exceeded the recommended occluding pressure of the tourniquet. This finding is proposed as one of the possible reasons for the occasional observation that convulsions may occur during Bier's block despite the presence of an intact tourniquet system.

Anesthesia, Conduction↗
PubMed1982

Alas, Memphis!

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History, Modern 1601-↗