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Biomedical subjects

D Gordon

Publications and source records attributed to D Gordon.

At least 217 records · Page 12Linked to original sources
PubMed1996

Unilateral vulvar edema associated with paracentesis in patients with severe ovarian hyperstimulation syndrome. A report of nine cases.

BACKGROUND: Severe ovarian hyperstimulation syndrome is a life-threatening complication of ovulation induction. The clinical picture includes ovarian enlargement, accumulation of ascites and pleural effusion, increased coagulability and electrolyte disorders. Accumulation of ascites increases the intraabdominal pressure so that breathing difficulties ensue. Paracentesis is the only treatment that can immediately prevent respiratory deterioration. CASES: Nine women with severe ovarian hyperstimulation syndrome were treated by paracentesis for the drainage of massive ascites. Unilateral vulvar edema developed in all cases in which the lower abdomen was the puncturing site. This phenomenon was not observed when paracentesis was carried out through the upper abdomen. The edema resolved spontaneously over the subsequent 10 days. CONCLUSION: Apparently the puncturing needle created a fistulous tract through which the ascitic fluid was forced, by the increased intraabdominal pressure, into the subcutaneous tissues, presenting as unilateral vulvar edema. This can be prevented by using one of the abdominal hypochondriac regions as the puncturing site. This phenomenon is self-limited and causes only mild discomfort without late sequelae.

Adult↗
PubMed1995

DNA binding properties of the Saccharomyces cerevisiae DAT1 gene product.

The DAT1 gene of Saccharomyces cerevisiae encodes a DNA binding protein (Dat1p) that specifically recognizes the minor groove of non-alternating oligo(A).oligo(T) tracts. Sequence-specific recognition requires arginine residues found within three perfectly repeated pentads (G-R-K-P-G) of the Dat1p DNA binding domain [Reardon, B. J., Winters, R. S., Gordon, D., and Winter, E. (1993) Proc. Natl. Acad. Sci. USA 90, 11327-1131]. This report describes a rapid and simple method for purifying the Dat1p DNA binding domain and the biochemical characterization of its interaction with oligo(A).oligo(T) tracts. Oligonucleotide binding experiments and the characterization of yeast genomic Dat1p binding sites show that Dat1p specifically binds to any 11 base sequence in which 10 bases conform to an oligo(A).oligo(T) tract. Binding studies of different sized Dat1p derivatives show that the Dat1p DNA binding domain can function as a monomer. Competition DNA binding assays using poly(I).poly(C), demonstrate that the minor groove oligo(A).oligo(T) constituents are not sufficient for high specificity DNA binding. These data constrain the possible models for Dat1p/oligo(A).oligo(T) complexes, suggest that the DNA binding domain is in an extended structure when complexed to its cognate DNA, and show that Dat1p binding sites are more prevalent than previously thought.

Binding, Competitive↗
PubMed1995

Direct gene transfer for treatment of human cancer.

Genetic instability within malignant cells gives rise to mutant proteins which can be recognized by the immune system. Recognition of tumor-associated antigens by T lymphocytes could thus contribute to the elimination of neoplastic cells. We have developed a molecular genetic intervention for the treatment of malignancies based upon the knowledge that foreign major histocompatibility complex (MHC) proteins expressed on the cell surface are efficient at stimulating an immune response. Expression of this foreign MHC gene within tumors induced a cytotoxic T cell response to the introduced gene. More importantly, the immune system recognized tumor-specific antigens on unmodified tumor cells as foreign. Growth of the tumors diminished, and in many cases, there was complete regression. This research provides evidence that direct gene transfer in vivo can induce cell-mediated immunity against specific gene products, and offers the potential for effective immunotherapy for the treatment of cancer and infectious diseases in man. Our laboratory conducted a phase I clinical trial to determine the safety and efficacy of this treatment in humans. These studies suggest that direct gene transfer provides a safe and feasible approach for the treatment of human cancer. More recent developments using combination gene therapy and the initiation of a second human trial with improvements on this technology have been implemented. Finally, we have begun to define mechanisms of resistance to immune recognition by established malignancies.

Animals↗
PubMed1995

Expression of an Arabidopsis cryptochrome gene in transgenic tobacco results in hypersensitivity to blue, UV-A, and green light.

The Arabidopsis HY4 gene, required for blue-light-induced inhibition of hypocotyl elongation, encodes a 75-kDa flavoprotein (CRY1) with characteristics of a blue-light photoreceptor. To investigate the mechanism by which this photoreceptor mediates blue-light responses in vivo, we have expressed the Arabidopsis HY4 gene in transgenic tobacco. The transgenic plants exhibited a short-hypocotyl phenotype under blue, UV-A, and green light, whereas they showed no difference from the wild-type plant under red/far-red light or in the dark. This phenotype was found to cosegregate with overexpression of the HY4 transgene and to be fluence dependent. We concluded that the short-hypocotyl phenotype of transgenic tobacco plants was due to hypersensitivity to blue, UV-A, and green light, resulting from over-expression of the photoreceptor. These observations are consistent with the broad action spectrum for responses mediated by this cryptochrome in Arabidopsis and indicate that the machinery for signal, transduction required by the CRY1 protein is conserved among different plant species. Furthermore, the level of these photoresponses is seen to be determined by the cellular concentration of this photoreceptor.

Arabidopsis↗
PubMed1995

Alpha-scorpion toxins binding on rat brain and insect sodium channels reveal divergent allosteric modulations by brevetoxin and veratridine.

At least six topologically separated neurotoxin receptor sites have been identified on sodium channels that reveal strong allosteric interactions among them. We have studied the allosteric modulation induced by veratridine, binding to receptor site 2, and brevetoxin PbTx-1, occupying receptor site 5, on the binding of alpha-scorpion toxins at receptor site 3, on three different neuronal sodium channels: rat brain, locust, and cockroach synaptosomes. We used 125I-AaH II, the most active alpha-scorpion toxin on vertebrates, and 125I-Lqh alpha IT, shown to have high activity on insects, as specific probes for receptor site 3 in rat brain and insect sodium channels. Our results reveal that brevetoxin PbTx-1 generates three types of effects at receptor site 3:1) negative allosteric modulation in rat brain sodium channels, 2) positive modulation in locust sodium channels, and 3) no effect on cockroach sodium channel. However, PbTx-1 activates sodium channels in cockroach axon similarly to its activity in other preparation. Veratridine positively modulates both rat brain and locust sodium channels but had no effect on alpha-toxin binding in cockroach. The dramatic differences in allosteric modulations in each sodium channel subtype suggest structural differences in receptor sites for PbTx-1 and/or at the coupling regions with alpha-scorpion toxin receptor sites in the different sodium channels, which can be detected by combined application of specific channel modifiers and may elucidate the dynamic gating activity and the mechanism of allosteric interactions among various neurotoxin receptors.

Allosteric Regulation↗
PubMed1995

A 30-amino acid truncation of the microsomal triglyceride transfer protein large subunit disrupts its interaction with protein disulfide-isomerase and causes abetalipoproteinemia.

The microsomal triglyceride transfer protein (MTP) is a heterodimer composed of the multifunctional enzyme, protein disulfide-isomerase, and a unique large, 97 kDa, subunit. It is found as a soluble protein within the lumen of the endoplasmic reticulum of liver and intestine and is required for the assembly of very low density lipoproteins and chylomicrons. Mutations in MTP which result in an absence of MTP function have been shown to cause abetalipoproteinemia. Here, the gene encoding the MTP 97-kDa subunit of an abetalipoproteinemic subject, which we have previously demonstrated lacks MTP activity and protein (Wetterau, J. R., Aggerbeck, L. P., Bouma, M.-E., Eisenberg, C., Munck, A., Hermier, M., Schmitz, J., Gay, G., Rader, D. J., and Gregg, R. E. (1992) Science 258, 999-1001), was isolated and sequenced. A nonsense mutation, which predicts the truncation of the protein by 30 amino acids, was identified. To investigate if this apparently subtle change in MTP could explain the observed absence of MTP, protein disulfide-isomerase was co-expressed with either the normal or mutant MTP 97-kDa subunit in Sf9 insect cells using a baculovirus expression system. Although there were high levels of expression of both the normal and mutant forms of the MTP 97-kDa subunit, only the normal subunit was able to form a stable, soluble complex with protein disulfide-isomerase. These results indicate that the carboxyl-terminal 30 amino acids of the MTP 97-kDa subunit plays an important role in its interaction with protein disulfide-isomerase.

Abetalipoproteinemia↗
PubMed1995

Isolation of differentially expressed sequence tags from steroid-responsive cells using mRNA differential display.

Transcriptional control of steroid-regulated gene networks by nuclear receptor proteins results in the coordinate expression of a limited number of target genes. Although much is known about the structure and function of steroid receptors, relatively few cell-specific steroid-regulated genes have been isolated and characterized. In this paper we describe results using mRNA differential display reverse transcriptase PCR (DDPCR) to identify and isolate short cDNA sequence tags from thymocyte and prostate cells under various hormone conditions. Using this technique we have isolated several differentially expressed sequence tags (DESTs) from the mouse thymocyte cell line WEHI 7.2. Two of these DESTs, GIG10 and GIG18, are rapidly induced by dexamethasone within 2 h of treatment. GIG10 is a novel sequence and GIG18 is the mouse homologue of a human expressed sequence tag isolated from activated B lymphocytes. We also used DDPCR to isolate DESTs from androgen-modulated rat ventral prostate tissue, one of which we characterized and found to correspond to the 3' end of prostatic spermine binding protein mRNA, a known androgen-regulated gene. Modifications of the original DDPCR protocol, which we found can potentially decrease the frequency of isolating false-positive DESTs, are described and the merits of DDPCR, relative to other differential cDNA cloning strategies, are discussed.

Androgens↗
PubMed1995

A new conotoxin affecting sodium current inactivation interacts with the delta-conotoxin receptor site.

We describe a new peptide conotoxin affecting sodium current inactivation, that competes on binding with delta-conotoxin TxVIA (delta TxVIA). The amino acid sequence of the new toxin, designated conotoxin NgVIA (NgVIA), is SKCFSOGTFCGIKOGLCCSVRCFSLFCISFE (where O is trans-4-hydroxyproline). The primary structure of NgVIA has an identical cysteine framework and similar hydrophobicity as delta TxVIA but differs in its net charge. NgVIA competes with delta TxVIA on binding to rat brain synaptosomes and molluscan central nervous system and strongly inhibits sodium current inactivation in snail neurons, as does delta TxVIA. In contrast to delta TxVIA, NgVIA is a potent paralytic toxin in vertebrate systems, its binding appears to be voltage-dependent, and it synergically increases veratridine-induced sodium influx to rat brain synaptosomes. delta TxVIA acts as a partial antagonist to NgVIA in rat brain in vivo. NgVIA appears to act via a receptor site distinct from that of delta TxVIA but similar to that of Conus striatus toxin. This new toxin provides a lead for structure-function relationship studies in the delta-conotoxins and will enable analysis of the functional significance of this complex of receptor sites in gating mechanisms of sodium channels.

Amino Acid Sequence↗
PubMed1995

Analysis of nicotinic acetylcholine receptor subunits in the cochlea of the mouse.

The present study was designed to catalogue and compare nicotinic receptor subunit messages in the mammalian cochlea. Fourteen nicotinic acetylcholine receptor subunit messages were examined by polymerase chain reaction (PCR) analysis and nucleotide sequencing. Total RNA was extracted from the auditory organs of 14- to 18-day-old CBAJ mice, and mRNA was purified using oligo-dT cellulose. After reverse transcription, resulting cDNA was amplified by PCR with the use of primers specific for the nucleotide sequences representing the following nicotinic receptor subunits: muscle types alpha 1, beta 1, gamma, delta and epsilon and neuronal types alpha 2,3,4,5,6,7 and beta 2,3,4. cDNA from cochlear tissue corresponding to the muscle-type receptor subunit beta 1 and to neuronal-type receptor subunits alpha 2,4,5,6 and beta 2,3 was amplified, whereas cDNA for muscle types alpha 1, gamma, delta and epsilon and neuronal types alpha 3,7 and beta 4 was not. All PCR products were homologous in nucleotide sequence to the corresponding reference cDNAs from which the primers were designed. The current results indicate that nicotinic acetylcholine receptor (nAChR) subunits that are similar or identical to the stated muscle and neuronal types are expressed in the murine cochlea. The presence of messages corresponding to the muscle-type beta 1 and neuronal-type nAChR subunits may be correlated with the atypical cholinergic response of cochlear hair cells to agonists and antagonists.

Animals↗
PubMed1995

Phenotype of patients with peroxisomal disorders subdivided into sixteen complementation groups.

OBJECTIVE: To use the technique of complementation analysis to help define genotype and classify patients with clinical manifestations consistent with those of the disorders of peroxisome assembly, namely the Zellweger syndrome (ZS), neonatal adrenoleukodystrophy (NALD), infantile Refsum disease (IRD), and rhizomelic chondrodysplasia punctata (RCDP). STUDY DESIGN: Clinical findings, peroxisomal function, and complementation groups were examined in 173 patients with the clinical manifestations of these disorders. RESULTS: In 37 patients (21%), peroxisome assembly was intact and isolated deficiencies of one of five peroxisomal enzymes involved in the beta-oxidation of fatty acids or plasmalogen biosynthesis were demonstrated. Ten complementation groups were identified among 93 patients (54%) with impaired peroxisome assembly and one of three phenotypes (ZS, NALD, or IRD) without correlation between complementation group and phenotype. Forty-three patients (25%) had impaired peroxisome assembly associated with the RCDP phenotype and belonged to a single complementation group. Of the 173 patients, 10 had unusually mild clinical manifestations, including survival to the fifth decade or deficits limited to congenital cataracts. CONCLUSIONS: At least 16 complementation groups, and hence genotypes, are associated with clinical manifestations of disorders of peroxisome assembly. The range of phenotype is wide, and some patients have mild involvement.

Acyltransferases↗
PubMed1995

Genetic modification of human peripheral blood lymphocytes with a transdominant negative form of Rev: safety and toxicity.

A transdominant mutant form of the rev gene, M10, confers resistance to infection by the human immunodeficiency virus (HIV) in vitro and is currently under investigation as a potential intervention in acquired immunodeficiency syndrome (AIDS). In this report, we examine three issues relevant to the safety of autologous transfer of human T cells genetically modified with Rev M10. First, the potential for malignant transformation was assessed in vitro using interleukin-2 (IL-2) dependence and fibroblast transformation assays, and tumorigenicity was evaluated in severe combined immunodeficient (SCID) mice. Possible toxicity was evaluated by pathologic analysis following adoptive transfer of genetically modified human T cells into SCID mice. Second, methods were developed that permit T cell activation required for gene transfer but do not allow replication of endogenous HIV. Third, T cell function was evaluated in peripheral blood lymphocytes (PBL) of HIV-seropositive donors transduced with Rev M10 and compared to a negative control mutant, delta Rev M10. By all criteria, no oncogenicity or toxicity was observed. Human T cells transduced with these vectors did not grow in the absence of IL-2 in vitro, and no tumors were observed following transplantation of genetically modified human cells into recipient SCID mice. Histopathological analysis of heart, lung, liver, spleen, and kidney of animals 1-21 weeks following adoptive transfer of gene-modified human T cells revealed no significant abnormalities. Additionally, no differences were observed in the pattern of cytokine secretion in enriched human PBL expressing Rev M10 compared to delta Rev M10. (ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Concentration of circulating plasma endothelin in patients with angina and normal coronary angiograms.

BACKGROUND: Some patients with angina pectoris and normal coronary arteriograms have reduced coronary flow reserve and abnormal endothelium dependent vasodilator responses. Endothelin-1 (ET-1), a potent vasoconstrictor, is an important modulator of microvascular function and may also have algogenic properties. METHOD: Plasma ET-1 was measured in peripheral venous blood in 40 patients (30 women) (mean (SD) age 56 (8) years) with angina and normal coronary arteriograms and 21 normal controls (17 women) (mean (SD) age 53 (7) years). Patients with systemic hypertension, left ventricular hypertrophy, or coronary spasm were excluded. Plasma ET-1 was measured using radioimmunoassay. RESULTS: Thirty five patients had > or = 1 mm ST segment depression during exercise. Left bundle branch block was present in four patients at rest and in one during exercise. Mean (SD) (range) concentration of ET-1 (pg/ml) was higher in patients than in controls (3.84 (1.25) (1.97-7.42) v 2.88 (0.71) (1.57-4.48) P < 0.0001). In patients with "high" (> control mean (one SD)) ET-1 concentrations (n = 23), the time to onset of chest pain during exercise was significantly shorter (6.21 (3.9) v 9.03 (3.9) min; p = 0.01) than in patients with "low" ET-1 concentrations. Of the five patients with left bundle branch block, four had plasma ET-1 concentration > 4.0 pg/ml. CONCLUSION: Plasma endothelin is raised in patients with angina and normal coronary arteriograms and is consistent with the demonstration of endothelial dysfunction in such patients. The association between "high" plasma ET-1 and an earlier onset of chest pain during exercise suggests that endothelin may also have a role in the genesis of chest pain in patients with normal coronary arteries.

Adult↗
PubMed1995

Census based deprivation indices: their weighting and validation.

KEY ISSUES--Over one hundred years of social science research has shown that different social groups have different probabilities of suffering from multiple deprivation; yet census based deprivation indices frequently assign equal weightings to each of their component variables. This becomes highly problematic when these indices are used as the basis for allocating resources to local and health authorities. In order to ensure fairness and accuracy in resource allocation these indices should be both weighted and validated. STUDY RESULTS--Weightings are derived from the Breadline Britain in the 1990s survey to produce a census based deprivation index that estimates the percentage of poor households at electoral ward level. Examples of validation methodology are discussed and the estimate of the proportion of poor households is shown to be highly correlated with both low income and morbidity as estimated from the 1991 census. DATA SOURCES--The 1991 census local base statistics (LBS) and small area statistics (SAS) aggregated for the 8519 electoral wards of England. The Breadline Britain in the 1990s survey: a nationally representative survey of 1831 households specifically designed to measure poverty and multiple deprivation.

Data Collection↗
PubMed1995

Expression and function of a recombinant PDGF B gene in porcine arteries.

Platelet-derived growth factor (PDGF) B is a mitogen and chemoattractant for smooth muscle cells in vitro, and expression of a recombinant PDGF B gene in porcine arteries stimulates intimal thickening. To define the mechanisms by which PDGF B gene expression induces intimal thickening in vivo, we examined its effects on smooth muscle cell proliferation and migration, extracellular matrix synthesis, and inflammatory cell infiltration in intimal lesions of pig arteries after direct gene transfer of a recombinant PDGF B gene. PDGF B gene expression was associated with rapid formation of an intima, including 3- to 10-fold increases in intimal thickness and intima-to-media area ratio 4 to 21 days after gene transfer compared with control transfected arteries. Intimal smooth muscle cell proliferation was detected at 2 days, peaked at 7 days (P < .01), and declined by 14 days, although the total number of intimal nuclei progressively increased to 21 days (P < .01). Calculations of expected-to-observed ratios of intimal cells, based on BrdC proliferation indexes, demonstrated that the increases in intimal cell number on days 2 through 7 could not be accounted for by proliferation alone, suggesting that recombinant PDGF BB acts to stimulate cell proliferation and migration of smooth muscle cells into the intima. Extracellular matrix deposition and procollagen synthesis were observed after 7 days (P < .01) and were associated with a decline in cell density in the intima, suggesting that extracellular matrix synthesis may contribute to progressive intimal thickening in response to PDGF B gene expression. There was minimal accumulation of inflammatory cells, including macrophages and CD3(+) lymphocytes, in transfected arteries. These data suggest that PDGF B gene expression promotes intimal expansion by both proliferation and migration of smooth muscle cells followed by synthesis of extracellular matrix and therefore acts through several mechanisms to play a role in the pathogenesis of intimal lesions in vivo.

Animals↗
PubMed1995

Nitric oxide-generating compounds inhibit total protein and collagen synthesis in cultured vascular smooth muscle cells.

Nitric oxide (NO) participates in the regulation of vascular tone and smooth muscle cell proliferation, but little is known of its effect on total protein and matrix synthesis in smooth muscle. We studied the effects of the NO-generating compounds S-nitroso-N-acetylpenicillamine (SNAP, 0.4 to 1.2 mmol/L) and sodium nitroprusside (SNP, 0.1 to 0.5 mmol/L) on total protein (using [3H]leucine) and collagen (using [3H]proline) synthesis in cultured rabbit aortic smooth muscle cells. Both agents caused dose-dependent inhibition of the relative rate of protein (maximum reduction of 87% [SNAP] and 80% [SNP]) and collagen synthesis, as measured by trichloroacetic acid-precipitated label. The magnitudes of percent inhibition of total protein and collagen synthesis were approximately equal. Inhibition of protein synthesis by SNAP and SNP was prevented by hemoglobin (10 mumol/L), suggesting that the protein synthesis inhibition was due to NO release. Inhibition of protein synthesis was reversible after removal of SNAP and SNP and was not caused by damage to the cells. These results suggest that NO may function as a modulator of vascular smooth muscle cell protein synthesis and production of extracellular matrix components.

Animals↗