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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
PubMed1986

Sequencing and identification of a cDNA clone for tomato polygalacturonase.

The 2a isoenzyme of tomato polygalacturonase was purified from ripe fruit and characterised. The N-terminal amino acid sequence of the protein was determined in order to identify polygalacturonase cDNA clones. The nucleotide sequence of a ripening-related cDNA (pTOM 6) was determined and found to encode the N-terminal sequence of mature polygalacturonase 2a. The complete open reading frame encodes a polypeptide of molecular weight 50,051, including a putative pre-sequence of 71 amino acids.

Amino Acid Sequence↗
PubMed1986

Synthesis of growth hormone-prolactin chimeric proteins and processing mutants by the exchange and deletion of genomic exons.

To test the feasibility of synthesizing recombinant peptide hormones by exon deletion and exchange, we have constructed and expressed hybrid human growth hormone (hGH)-rat prolactin (rPrl) genes in which the third and fourth exons of the hGH gene are deleted and separately replaced by the corresponding exons of the rPrl gene. These exon deletion and exon exchange genes were inserted into an SV40 viral vector, packaged, and expressed following acute viral infection of monkey kidney cells. Expression of the hGH gene lacking the third exon (hGHd3) was not detectable at the level of protein production. However, replacement of the deleted third exon in the hGHd3 gene with exon 3 of the rPrl gene (hGHP3) resulted in the efficient synthesis of a secreted chimeric protein. When the fourth exon of the hGH gene was deleted (hGHd4), the encoded protein was found only in the cytosol despite signal sequence processing. Replacement of the deleted fourth exon in this hGHd4 gene with exon 4 of rPrl resulted in the synthesis and secretion of both a chimeric protein (hGHP4) as well as a larger protein corresponding in size to prehGHP4. These results suggest that exon exchange among distantly related genes in the GH family may be used to produce high levels of chimeric GH-related proteins, and regions internal to the hGH protein may be critical in establishing normal protein processing and secretion.

Chimera↗
PubMed1986

Allosteric sensitivity in hemoglobin at the alpha-subunit N-terminus studied by hydrogen exchange.

Allosteric structure change in human hemoglobin was studied by hydrogen-tritium-exchange methods. The functional labeling method used takes advantage of the change in H-exchange rate at allosterically involved sites to selectively label, with tritium, H-exchange sites that are fast in one protein state and slow in another. The position of the labeled sites can then be located by the medium-resolution fragmentation-separation method. These methods reveal 5 allosterically sensitive, H-bonded, peptide NH's within the first 12 residues of the alpha chain. All five exchange with solvent protons at similar rates in deoxyhemoglobin (T form), and all shift to a new rate, about 30-fold faster, in the liganded protein (R) form. This indicates a decrease in structural stability at the alpha-chain N-terminus in going from the T to the R form, consistent with the loss of stabilizing interactions in that segment. The results indicate a loss of perhaps 2 kcal/mol in stabilization free energy and thus document a significant role for changes at the alpha-chain N-terminus in the allosteric transition.

Allosteric Regulation↗
PubMed1986

Expression and site-specific mutagenesis of the poliovirus 3C protease in Escherichia coli.

We have engineered a segment of the poliovirus genome (nucleotides 5438-6061) that encodes the 183 amino acid residues of the 3C region and 25 residues of the 3D region of the viral polyprotein into an Escherichia coli expression vector. The 3C region is a virus-specific protease, which, when expressed in E. coli, is shown to be active and autocatalytic. In our system, three poliovirus-specific proteins are produced: a precursor polyprotein (3C-3D), an internal initiation product, and the mature protease (3C). Mutants in the 3C region have been constructed by oligonucleotide-directed mutagenesis and their effect on the proteolytic activity has been assayed by the in vivo production of the mature protease. The mutation of highly conserved residues (cysteine-47 or histidine-161) produced an inactive enzyme, while the mutation of a nonconserved residue (cysteine-153) had a negligible effect on the proteolytic activity.

Cloning, Molecular↗
PubMed1985

Main and interaction effects of metallic toxins on classroom behavior.

This study investigated the relationships of metal levels and metal combinations to children's classroom behavior. Hair-metal concentrations of lead, arsenic, mercury, cadmium, and aluminum were determined in 80 randomly selected elementary-age children, who were also rated by their classroom teacher on the Walker Problem Behavior Identification Checklist (WPBIC). Parents were interviewed to control for confounding variables that may have affected behavioral development. Regression analysis indicated that the set of metals was significantly related to increased scores on four of the five WPBIC subscales and on the total scale, with lead being a major contributor to four of the six dependent measures. Metal combinations were significantly related to increased scores on the WPBIC subscales measuring acting-out, disturbed peer relations, and immaturity, and on the total scale. A continuing reexamination of metal poisoning concentrations is needed because metal levels and metal combinations previously thought harmless may be associated with nonadaptive classroom behavior.

Aluminum↗
PubMed1985

Non-clear-cell adenocarcinoma arising in vaginal adenosis.

We report a case of adenocarcinoma of the vagina occurring in a woman without exposure to diethylstilbestrol. The adenocarcinoma arises in benign adenosis and lacks a clear-cell component. Both the adenosis and adenocarcinoma appear to be of müllerian origin.

Adenocarcinoma↗
PubMed1982

A biologically active receptor for the carbohydrate-binding protein(s) of Dictyostelium discoideum.

Recent biochemical and genetic evidence has shown that carbohydrate-binding protein (CBP-26) is intimately involved in the cell-cell cohesion process. We have isolated a cell-surface-associated receptor molecule for CBP-26 by affinity chromatography. The receptor has a molecular weight of 80,000 daltons. The CBP receptor is constitutively expressed during development. Most significantly, the receptor, when added to aggregation-competent cells, blocks the cells' ability to reaggregate. These results suggest that CBP and its receptor play an important role in the cell cohesion and aggregation process.

Cell Aggregation↗
PubMed1981

Differential effects of ibuprofen and indomethacin in the regional circulation of the dog.

The effects of indomethacin and ibuprofen on aortic blood pressure and regional vascular resistances were studied in pentobarbital-anesthetized dogs. In the mesenteric vascular bed, indomethacin produced severe, acute vasoconstriction when administered by i.v. infusion as well as by i.a. injections. Tachyphylaxis developed rapidly to this response. In contrast. ibuprofen did not alter mesenteric blood flow even when a large (50 mg) i.v. bolus was rapidly injected. The mesenteric vasoconstrictor response to indomethacin was not modified when prostaglandin synthesis was inhibited or in the presence of cyproheptadine. Phentolamine exerted only a minor influence on the mesenteric vascular effect of indomethacin. The effects of indomethacin and ibuprofen on aortic blood pressure and renal blood flow were similar. Both agents increased aortic pressure and decreased renal blood flow a small but significant amount, but these responses occurred slowly and were probably not related to the acute mesenteric vasoconstricting effect or indomethacin. The present study demonstrates that these nonsteroidal anti-inflammatory agents have different effects on the mesenteric vascular bed and the data suggest that the vasoconstricting effects of indomethacin are not related to the inhibition of prostaglandin synthesis in the intestine. The data also suggest that the acute vasoconstriction in the mesenteric circulation produced by indomethacin is not mediated to a significant degree by local release of alpha adrenergic agents or serotonin.

Animals↗
PubMed1979

A mutation altering the function of a carbohydrate binding protein blocks cell-cell cohesion in developing Dictyostelium discoideum.

In Dictyostelium discoideum, carbohydrate binding proteins (CBPs) or lectins have been implicated in the molecular basis of cellular cohesion. To determine the role of these CBPs, we have attempted to isolate structural gene mutants in which the CBPs have a defective affinity for carbohydrate ligands. We now report the isolation of a spontaneous, cross-reacting material (CRM) mutant which is non-cohesive and fails to develop. The mutant seems to have a defect in the structural gene for one of the two developmentally regulated carbohydrate binding proteins (CBP-26), which renders it unable to bind to galactose-containing ligands. The fact that wild-type cells interact with the mutant and carry it through development strongly supports a model of cell-cell interaction in which cohesion is mediated by complementary molecules.

Carrier Proteins↗
PubMed1978

Use of common plant lectins for isolation and characterization of constitutive and developmentally regulated cell surface associated glycoproteins of Dictyostelium discoideum.

Glycoproteins as a class of molecules have been implicated as serving crucial roles in cell recognition events. Using 3 common plant lectins, we have isolated and identified a number of cell surface associated glycoproteins. The appearance of at least 5 of these proteins is under developmental regulation.

Chromatography, Affinity↗
PubMed1977

Electrogoniometric analysis of equine metacarpophalangeal joint lameness.

Electrogoniometry was used qualitively and quantitatively to assess the movements of the normal and pathologic metacarpophalangeal joints of selected horses. A total of 4 Thoroughbreds, 1 normal and 3 with clinical and radiographic changes in the metacarpophalangeal joints of 1 limb, were evaluated at the walk and trot. Goniograms of the affected joints were compared with those of the normal horse and the normal contralateral metacarpophangeal joint. Qualitative asymmetry was recognized on the goniograms, and the ranges of motion were quantified and related to the clinical and radiologic observations.

Animals↗