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Biomedical subjects

J Ray

Publications and source records attributed to J Ray.

At least 127 records · Page 7Linked to original sources
PubMed1991

Is there a relationship between presbycusis and hyperlipoproteinemia? A literature review.

This paper reviews several articles on the subject of presbycusis, and its relationship to dietary lipids--particularly lipoproteins--as well as hypertension, and noise exposure. Although most studies do reach some sort of consensus, the evidence supporting a relationship between presbycusis and hyperlipoproteinemia (HLP) remains questionable. The etiology of such a connection has not been properly tested, probably due to inadequate laboratory techniques. Future opportunities for exploring this subject are considerable, both in the laboratory and clinical setting. Possible treatment measures for "HLP-hearing loss" are also reviewed.

Adult↗
PubMed1990

Human growth hormone-variant demonstrates a receptor binding profile distinct from that of normal pituitary growth hormone.

We have recently established that the human growth hormone-variant (hGH-V) gene is functional in vivo by documenting its expression in the placenta. We have subsequently generated transformed murine cell lines stably expressing the genes for normal pituitary growth hormone (hGH-N), hGH-V, and each of two chimeric genes generated by exon 3 exchanges, hGH-NV3 and hGH-VN3. In the present study, we utilize these cell lines as sources of hormone to characterize and compare the receptor binding profiles of hGH-N with hGH-V. hGH-V was found to displace 125I-ovine prolactin bound to rat liver microsomes (lactogen binding) and to displace 125I-hGH bound to rabbit liver microsomes (somatogen binding). Therefore, hGH-V would be predicted to display both somatogenic and lactogenic bioactivity, a dual specificity previously thought to be unique to hGH-N. The concentrations of hormone necessary to displace 50% (IC50) of the 125I-hGH from somatogen receptors and 125I-ovine prolactin from lactogen receptors was expressed as a ratio, IC50 somatogen: IC50 lactogen, for each hormone tested. A 7.4-fold difference in this ratio was observed for hGH-N compared to hGH-V, suggesting significantly greater selectivity by hGH-V in binding to the somatogen receptor. The intermediate binding ratios of the hGH-NV3 and hGH-VN3 chimeric proteins confirmed the distinct receptor binding profiles of the two parent hormones and served to identify three amino acids of potential importance in defining their respective receptor binding specificities.

Amino Acid Sequence↗
PubMed1990

Expression of a truncated tomato polygalacturonase gene inhibits expression of the endogenous gene in transgenic plants.

Tomato plants were transformed with a chimaeric polygalacturonase (PG) gene, designed to produce a truncated PG transcript constitutively. In these plants expression of the endogenous PG gene was inhibited during ripening, resulting in a substantial reduction in PG mRNA and enzyme accumulation. This inhibition was comparable to that achieved previously using antisense genes. The expression of the truncated gene in ripe fruit was substantially lower than its expression in green fruit. Thus expression of both the endogenous and truncated genes is reduced in ripe fruit in which both are active. The implication of this observation is discussed in relation to the possible mechanism whereby sense constructs inhibit gene expression.

Blotting, Northern↗
PubMed1990

Primary malignant melanoma of the uterine cervix: two case reports and a century's review.

Primary malignant cervical melanoma is diagnosed by the presence of junctional melanocytic abnormality and the absence of distant metastasis. Amelanotic and poorly differentiated tumors can often be diagnosed with the HMB-45 immunoperoxidase stain which is very specific for melanoma. Early reported cases were treated with simple excision followed many times by radiation therapy. Radical hysterectomy, pelvic lymphadenectomy, and partial vaginectomy have been advocated by some contemporary investigators. Radiation can be used as adjuvant or palliative treatment; its efficacy is not well established. Few patients have been treated with modern chemotherapy. No patient has been treated with immunotherapy. Primary malignant cervical melanoma carries a very poor prognosis. Most patients succumb from their disease within 2 years. One patient has survived 14 years. The small number of reported cases makes it difficult to evaluate the efficacy of any treatment modality.

Adult↗
PubMed1990

Alteration in the receptor binding specificity of human growth hormone by genomic exon exchange.

The biological activities of the GH-PRL family of hormones are mediated by selective binding to two classes of cell membrane receptors, somatogen and lactogen. Primate GH such as human GH (hGH) are unusual in that they bind to both classes of receptors. Replacement of exons 3 or 4 of the hGH gene by the corresponding exons of the rat PRL or rat GH genes results in the synthesis of chimeric proteins which retain the ability to bind to lactogen receptors but can no longer bind to somatogen receptors. This selective loss of somatogen receptor binding in the chimeric proteins suggests that certain of the structural determinants of somatogen and lactogen receptor binding activities in hGH are distinct and can be separately modified by a limited number of amino acid substitutions.

Amino Acid Sequence↗
PubMed1989

Control and manipulation of gene expression during tomato fruit ripening.

Ripening is a complex developmental process involving changes in the biochemistry, physiology and gene expression of the fruit. It is an active process characterised by changes in all cellular compartments. cDNA cloning has been used as an approach to analyse changes in gene expression during fruit ripening. This has revealed that several genes are switched on specifically during fruit ripening, including one encoding polygalacturonase (PG), a major cell wall protein. These cDNA clones have been used to study the expression of the genes in normal and ripening mutant fruits, and under environmental stress conditions. The PG gene has been isolated and it has been demonstrated that 1450 bases 5' of the coding region are sufficient for the tissue- and development-specific expression of a bacterial marker gene in transgenic tomatoes. Antisense RNA techniques have been developed to generate novel mutant tomatoes in which the biochemical function of this enzyme and its involvement in fruit softening has been tested.

Cloning, Molecular↗
PubMed1989

Personality profile and affective state of patients with inflammatory bowel disease.

The Eysenck Personality Inventory and Hospital Anxiety and Depression scale were administered to 80 patients undergoing medical treatment for long standing inflammatory bowel disease: 22 patients were studied before the diagnosis was established and 40 patients with diabetes mellitus served as controls. High neuroticism and introversion scores were more prevalent in the patients with inflammatory bowel disease than controls (p less than 0.05) and these characteristics were as prominent in patients before diagnosis as in established cases. Introversion scores increased with the duration of disease (r = 0.51). Depression was uncommon, occurring only in patients with active chronic disease. Patients believed there was a close link between personality, stress and disease activity. Fifty six of the patients recognised factors that initiated the disease and in 42 this was thought to be a stressful life event or a 'nervous personality'.

Affect↗
PubMed1989

Characterization and histologic localization of human growth hormone-variant gene expression in the placenta.

The human growth hormone-variant (hGH-V) gene is one of five highly similar growth hormone-related genes clustered on the short arm of chromosome 17. Although the pattern of expression of the adjacent normal growth hormone (hGH-N) and chorionic somatomammotropin (hCS) genes in this cluster are well characterized, the expression of the hGH-V gene remains to be defined. In previous studies, we have demonstrated that the hGH-V gene is transcribed in the term placenta and expressed as two alternatively spliced mRNAs: one is predicted to encode a 22-kD hormone (hGH-V), the other retains intron 4 in its sequence resulting in the predicted synthesis of a novel 26-kD hGH-V-related protein (hGH-V2). In the present report, we document the expression of both of these hGH-V mRNA species in the villi of the term placenta, demonstrate an increase in their concentrations during gestation, and directly sublocalize hGH-V gene expression to the syncytiotrophoblastic epithelium of the term placenta by in situ cDNA-mRNA histohybridization. The demonstrated similarity in the developmental and tissue-specific expression of the hGH-V gene with that of the related hCS gene suggests that these two genes may share common regulatory elements.

Animals↗
PubMed1989

Glycosylated human growth hormone variant.

The human growth hormone variant (hGH-V) gene is expressed by the syncytiotrophoblastic layer of the human placenta in two forms: hGH-V mRNA encoding a 22 kD protein, and hGH-V2 mRNA which retains intron 4 and is expected to encode a 26 kD protein. There is a predicted N-linked glycosylation site in hGH-V at amino acid 140 that is absent in both hGH-V2 and in the highly homologous normal pituitary GH (hGH-N). Cell lines transfected with the hGH-N gene secrete 22 kD GH and the 20 kD product of an alternatively spliced mRNA, while cell lines transfected with the hGH-V gene secrete three proteins of 22, 24, and 26 kD. To determine whether any of these hGH-V isoforms are glycosylated, the cell lines were grown in the absence and presence of tunicamycin. In addition, conditioned medium from metabolically labelled hGH-V transfected cells was separately digested with peptide:N-glycosidase F and endoglycosidase H. The 26 and 24 kD bands were both absent from the media after tunicamycin treatment and were both sensitive to peptide:N-glycosidase F treatment. Endoglycosidase H digestion resulted in the selective loss of the 24 kD band. These results indicate that hGH-V is partially modified posttranslationally by N-linked glycosylation in a fibroblastic cell line.

Animals↗
PubMed1989

Water-induced precipitation of cholesterol dissolved in organic solvents in the absence and presence of surfactants and salts.

The precipitation of cholesterol dissolved in organic solvents, viz. methanol, ethanol, n-propanol, isopropanol, acetone and 1,4-dioxane, by the addition of water has been studied. The effects of the solvents towards the precipitation follow the order: methanol greater than ethanol greater than acetone greater than dioxane greater than n-propanol greater than iso-propanol, the solvent dioxane however exhibits a change in the order at higher concentration. Additives like Triton X-100, sodium cholate, sodium deoxycholate, sodium dehydro cholate, sodium salicylate and sodium chloride have some protective action against precipitation, the maximum protection being that of Triton X-100. The additives have shown better protective action in propanols and dioxane than in methanol, ethanol and acetone. Analysis of solvent composition and dielectric constant has revealed specific solvent effects on the water-induced precipitation of cholesterol. Thermodynamic analysis of the precipitation phenomenon and the unique role of solvent structure on cholesterol precipitation has been discussed.

Bile Acids and Salts↗
PubMed1988

Two distinct species of human growth hormone-variant mRNA in the human placenta predict the expression of novel growth hormone proteins.

We have sought direct evidence for the in vivo expression of the human growth hormone-variant (hGH-V) gene by screening a placental cDNA library with a hGH-V-specific oligonucleotide. Nine independent hGH-V cDNA clones were isolated and analyzed, and three distinct species were detected. Five of these hGH-V cDNAs represent mRNAs spliced and processed in a pattern analogous to that of the highly homologous human growth hormone and human chorionic somatomammotropin gene transcripts. Each of the remaining four hGH-V cDNAs contains an additional segment of 253 nucleotides corresponding in position and sequence to the fourth intron of the hGH-V gene. In addition, one of the mRNAs in this second group uses an alternative downstream polyadenylation site. The alternatively spliced hGH-V mRNA, which we refer to as hGH-V2 mRNA, constitutes approximately 30% of the hGH-V transcripts both in the human term placenta and in a stable mouse fibroblast line expressing the transfected hGH-V gene. The placental expression of the hGH-V gene is specific to villous tissue. The hGH-V2 mRNA is predicted to encode a protein which substitutes the 65 carboxyl-terminal amino acids of hGH-V with a new 104-residue carboxyl terminus resulting in significant divergence in their relative physical properties. The alternative splicing of the hGH-V transcripts to hGH-V and hGH-V2 mRNAs expands the potential complexity of the hGH-V gene's role in normal placental function.

Amino Acid Sequence↗
PubMed1988

Identification and sequence determination of a cDNA clone for tomato pectin esterase.

Cell wall softening during tomato fruit ripening is brought about through the action of a number of pectolytic enzymes. We have reported previously the cloning and characterisation of the cDNA for the major cell wall softening (degrading) enzyme, polygalacturonase [Grierson, D., Tucker, G. A., Keen, J., Ray, J., Bird, C. R. and Schuch, W. (1986) Nucleic Acids Res. 14, 8595-8603]. We have now isolated a cDNA clone for tomato pectin esterase, an enzyme also implicated in cell wall softening. Here we report the structure of this cDNA and compare it with the structure of pectin esterase derived from amino acid sequence experiments [Markovic, O. and Jornvall, H. (1986) Eur. J. Biochem. 158, 455-462]. We have used the pectin esterase cDNA clone to analyse pectin esterase gene expression during development and ripening of normal and mutant fruit.

Amino Acid Sequence↗