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J R Hoidal

Publications and source records attributed to J R Hoidal.

At least 19 recordsLinked to original sources
PubMed2004

Polymorphisms in the 5'-UTR of the tissue factor gene are associated with altered expression in human endothelial cells.

BACKGROUND: Enhanced tissue factor (TF) expression mediates many disease processes. Recently, four completely concordant polymorphisms were detected in the 5'-UTR of the TF gene. Three were single base changes and one was an 18-bp insertion/deletion at -1208. OBJECTIVES: This study was undertaken to determine if the I-allele or the D-allele would associate with elevated TF expression in human umbilical vein endothelial cells (HUVEC). METHODS: HUVEC were genotyped by polymerase chain reaction for 18-bp insert status. TF expression was induced by interleukin (IL)-1 or phorbol 12-myristate 13-acetate (PMA). Total TF activity was determined by a one-stage clotting assay and surface TF activity by a chromogenic assay. Protein binding differences between the I- and D-alleles were examined by gel shift assays. RESULTS: IL-1- or PMA-induced total TF activity in D-allele HUVEC was increased 2.0-2.5-fold above that seen in II HUVEC. Surface clotting activity in D-allele cells was 1.3-1.7-fold greater than in II-allele cultures. Experiments with consensus site mutation oligos suggested that the 18-bp insert creates GATA and CCAAT-enhancer binding protein (C/EBP) transcription factor recognition sites. CONCLUSIONS: The D-allele is associated with enhanced TF activity in HUVEC. The differences in TF expression between the alleles may be due to variant transcription factor binding in the -1208 region. Further studies are warranted to investigate whether the D-allele is associated with increased incidence of pathological processes that involve TF.

5' Untranslated Regions↗
PubMed2003

Improved method for measurement of human plasma xanthine oxidoreductase activity.

The XOR activity in human plasma was measured by quantifying the XOR-derived uric acid (UA) in plasma using the high-performance liquid chromatography (HPLC) equipped with a UV detector. Chromatographic separation consisted of the mobile phase (a mixture of 0.1% trifluoroacetic acid in Milli-Q water and 0.085% trifluoroacetic acid in acetonitrile in a mix ratio of 99:1) running through a Zorbax StableBond SB-C(18) column at a flow-rate of 1 ml/min. Deproteinization with heat-treatment of plasma samples after the reaction was used in the assay to avoid splitting of the UA and xanthine peaks caused by acid deproteinization that could interfere the accurate determination of human plasma XOR activity in our case. Based on the examination of the dependence of XOR activity on added amounts of xanthine and reaction times, the amount of xanthine and reaction time for XOR activity assay were determined to prevent the errors caused by the limiting effect of substrates and plateau phase of the reaction. Using this method, human plasma XOR activities of 25 healthy people were measured. The average human plasma XOR activity was 2.1+/-0.8 (x10(-3) U/ml).

Chromatography, High Pressure Liquid↗
PubMed2003

Redox signaling of NF-kappaB by membrane NAD(P)H oxidases in normal and malignant cells.

Evidence is rapidly accumulating that low-activity NAD(P)H oxidases homologous to that in phagocytic cells generate reactive oxygen species as signaling intermediates. In this review we discuss evidence that signaling NAD(P)H oxidases in part influence normal and malignant cell division by activating the redox-regulated transcription factor nuclear factor kappaB. The roles of growth-regulatory NAD(P)H oxidases in human airway smooth muscle and malignant melanoma are used as examples.

Animals↗
PubMed2002

Role of components of the phagocytic NADPH oxidase in oxygen sensing.

It has been hypothesized that O(2) sensing in type I cells of the carotid body and erythropoietin (EPO)-producing cells of the kidney involves protein components identical to the NADPH oxidase system responsible for the respiratory burst of phagocytes. In the present study, we evaluated O(2) sensing in mice with null mutant genotypes for two components of the phagocytic oxidase. Whole body plethysmography was used to study unanesthetized, unrestrained mice. When exposed to an acute hypoxic stimulus, gp91(phox)-null mutant and wild-type mice increased their minute ventilation by similar amounts. In contrast, p47(phox)-null mutant mice demonstrated increases in minute ventilation in response to hypoxia that exceeded that of their wild-type counterparts: 98.0 +/- 18.0 vs. 20.0 +/- 13.0% (n = 11, P = 0.003). In vitro recordings of carotid sinus nerve (CSN) activity demonstrated that resting (basal) neural activity was marginally elevated in p47(phox)-null mutant mice. With hypoxic challenge, mean CSN discharge was 1.5-fold greater in p47(phox)-null mutant than in wild-type mice: 109.61 +/- 13.29 vs. 72.54 +/- 7.65 impulses/s (n = 8 and 7, respectively, P = 0.026). Consequently, the hypoxia-evoked CSN discharge (stimulus-basal) was approximately 58% larger in p47(phox)-null mutant mice. Quantities of EPO mRNA in kidney were similar in gp91(phox)- and p47(phox)-null mutant mice and their respective wild-type controls exposed to hypobaric hypoxia for 72 h. These findings confirm the previous observation that absence of the gp91(phox) component of the phagocytic NADPH oxidase does not alter the O(2)-sensing mechanism of the carotid body. However, absence of the p47(phox) component significantly potentiates ventilatory and chemoreceptor responses to hypoxia. O(2) sensing in EPO-producing cells of the kidney appears to be independent of the gp91(phox) and p47(phox) components of the phagocytic NADPH oxidase.

Animals↗
PubMed2001

Cloning and characterization of the cDNA and gene for human epitheliasin.

Previously, we reported cloning and characterization of the mouse gene, epitheliasin. In the present work we cloned the cDNA of the full-length human orthologue and characterized its gene including 2 kb of 5' flanking sequence. Analysis of epitheliasin gene expression in adult tissues shows that it is expressed as 3.4 kb and 2 kb transcripts. The major 3.4 kb transcript is observed in the following order: prostate > colon > small intestine > pancreas > kidney > lung > liver. Epitheliasin transcripts in fetal tissues are observed only in kidney and lung. In situ hybridization analysis of tissues revealed that epitheliasin was preferentially expressed in epithelial cells. The gene consists of 14 exons and 13 introns based on comparison with its cDNA sequence. In the 5' flanking region, we identified two transcription start sites and three CpG islands encompassing a number of potential regulatory elements including SP1, SREBP, GRE/PRE and ERE. The region upstream of the transcription sites lacks a TATA box but contains an initiator-like element as well as a downstream promoter-like element. In vitro experiments with lymph node carcinoma of prostate (LNCaP) cells revealed that the epitheliasin gene was induced by androgens and the induction was not blocked by cycloheximide indicating that the induction required no intermediate protein factors. Immunoprecipitation analysis showed that androgens strongly increased epitheliasin protein levels.

Adult↗
PubMed2001

Reactive oxygen species from NAD(P)H:quinone oxidoreductase constitutively activate NF-kappaB in malignant melanoma cells.

The transcription factor nuclear factor-kappaB (NF-kappaB) is constitutively activated in malignancies from enhanced activity of inhibitor of NF-kappaB (IkappaB) kinase, with accelerated IkappaBalpha degradation. We studied whether redox signaling might stimulate these events. Cultured melanoma cells generated superoxide anions (O(2)(-)) without serum stimulation. O(2)(-) generation was reduced by the NAD(P)H:quinone oxidoreductase (NQO) inhibitor dicumarol and the quinone analog capsaicin, suggesting that electron transfer from NQO through a quinone-mediated pathway may be an important source of endogenous reactive oxygen species (ROS) in tumor cells. Treatment of malignant melanoma cells with the H(2)O(2) scavenger catalase, the sulfhydryl donor N-acetylcysteine, the glutathione peroxidase mimetic ebselen, or dicumarol decreased NF-kappaB activation. Catalase, N-acetylcysteine, ebselen, dicumarol, and capsaicin also inhibited growth of melanoma and other malignant cell lines. These results raise the possibility that ROS produced endogenously by mechanisms involving NQO can constitutively activate NF-kappaB in an autocrine fashion and suggest the potential for new antioxidant strategies for interruption of oxidant signaling of melanoma cell growth.

Antioxidants↗
PubMed2001

Gadolinium chloride inhibits pulmonary macrophage influx and prevents O(2)-induced pulmonary hypertension in the neonatal rat.

Newborn rats exposed to 60% O(2) for 14 d demonstrated a bronchopulmonary dysplasia-like lung morphology and pulmonary hypertension. A 21-aminosteroid antioxidant, U74389G, attenuated both pulmonary hypertension and macrophage accumulation in the O(2)-exposed lungs. To determine whether macrophage accumulation played an essential role in the development of pulmonary hypertension in this model, pups were treated with gadolinium chloride (GdCl(3)) to reduce lung macrophage content. Treatment of 60% O(2)-exposed animals with GdCl(3) prevented right ventricular hypertrophy (p < 0.05) and smooth muscle hyperplasia around pulmonary vessels, but had no effect on morphologic changes in the lung parenchyma. In addition, GdCl(3) inhibited 60% O(2)-mediated increases in endothelin-1, 8-isoprostane, and nitrotyrosine residues. Organotypic cultures of fetal rat distal lung cells were subjected to cyclical mechanical strain to assess the potential role of GdCl(3)-induced blockade of stretch-mediated cation channels in these effects. Mechanical strain caused a moderate increase of endothelin-1 (p < 0.05), which was unaffected by GdCl(3), but had no effect on 8-isoprostane or nitric oxide synthesis. A critical role for endothelin-1 in O(2)-mediated pulmonary hypertension was confirmed using the combined endothelin receptor antagonist SB217242. We concluded that pulmonary macrophage accumulation, in response to 60% O(2), mediated pulmonary hypertension through up-regulation of endothelin-1.

Animals↗
PubMed2000

Repressed expression of the human xanthine oxidoreductase gene. E-box and TATA-like elements restrict ground state transcriptional activity.

Studies were initiated to address the basis for the low xanthine oxidoreductase (XOR) activity in humans relative to nonprimate mammalian species. The expression of the XOR in humans is strikingly lower than in mice, and both transcription rates and core promoter activity of the gene are repressed. Analysis of human XOR promoter activity in hepatocytes and vascular endothelial cells showed that the region from -258 to -1 contains both repressor and activator binding regions regulating core promoter activity. The region between -138 and -1 is necessary and sufficient for initiating, and the region between -258 and -228 is critical for restricting core promoter activity. Within the latter region, site-directed mutations identified a consensus sequence "acacaggtgtgg" (-242 to -230) that contains an E-box that binds a repressor. In addition, the TATA-like element is also required to restrict promoter activity and TFIID binds to this site. The results demonstrate that both an E-box and TATA-like element are required to restrict gene activity. A model is proposed to account for human XOR regulation.

5' Untranslated Regions↗
PubMed2000

Cloning, genomic organization, chromosomal assignment and expression of a novel mosaic serine proteinase: epitheliasin.

We report the isolation of a cDNA encoding a novel murine serine proteinase, epitheliasin. The cDNA spans 1753 bp and encodes a mosaic protein with a calculated molecular mass of 53529 Da. Its domains include a cytoplasmic tail, a type II transmembrane domain, a low-density lipoprotein receptor class A domain, a cysteine rich scavenger receptor-like domain and a serine proteinase domain. The proteinase portion domain shows 46-53% identity with mouse neurotrypsin, acrosin, hepsin and enteropeptidase. The gene, located in the telomeric region in the long arm of mouse chromosome 16, consists of 14 exons and 13 introns and spans approximately 18 kb. Epitheliasin is expressed primarily in the apical surfaces of renal tubular and airway epithelial cells.

Amino Acid Sequence↗
PubMed2000

Nonanticoagulant heparin inhibits NF-kappaB activation and attenuates myocardial reperfusion injury.

Heparin reduces ischemia-reperfusion injury to myocardium. This effect has been attributed to complement inhibition, but heparin also has other activities that might diminish ischemia-reperfusion. To further probe these mechanisms, we compared heparin or an o-desulfated nonanticoagulant heparin with greatly reduced anticomplement activity. When given at the time of coronary artery reperfusion in a canine model of myocardial infarction, heparin or o-desulfated heparin equally reduced neutrophil adherence to ischemic-reperfused coronary artery endothelium, influx of neutrophils into ischemic-reperfused myocardium, myocardial necrosis, and release of creatine kinase into plasma. Heparin or o-desulfated heparin also prevented dysfunction of endothelial-dependent coronary relaxation following ischemic injury. In addition, heparin and o-desulfated heparin inhibited translocation of the transcription nuclear factor-kappaB (NF-kappaB) from the cytoplasm to the nucleus in human endothelial cells and decreased NF-kappaB DNA binding in human endothelium and ischemic-reperfused rat myocardium. Thus heparin and nonanticoagulant heparin decrease ischemia-reperfusion injury by disrupting multiple levels of the inflammatory cascade, including the novel observation that heparins inhibit activation of the proinflammatory transcription factor NF-kappaB.

Animals↗
PubMed1999

Requirement for reactive oxygen species in serum-induced and platelet-derived growth factor-induced growth of airway smooth muscle.

Reactive oxygen species have been recently identified as important mediators of mitogenic signaling in a number of cell types. We therefore explored their role in mediating mitogenesis of airway smooth muscle. The antioxidants catalase, N-acetylcysteine, and probucol significantly reduced proliferation in primary cultures of rat tracheal smooth muscle stimulated with fetal bovine serum or platelet-derived growth factor, without affecting cell viability or inducing apoptosis. N-Acetylcysteine also significantly reduced serum-stimulated elevation of c-Fos but did not prevent the normal mitogen-induced increase in c-fos mRNA. Fractionation of ribosomes by sucrose density centrifugation and subsequent dot-blot Northern analysis revealed that antioxidants reduced incorporation of c-fos mRNA into the heaviest polyribosomes, suggesting redox regulation of c-fos mRNA translation. Serum treatment of monolayers produced a small but reproducibly significant rise in superoxide dismutase-inhibitable reduction of ferricytochrome c by myocyte monolayers. Serum-induced ferricytochrome c reduction, cellular proliferation, and c-Fos elevation were decreased by the flavoprotein-dependent enzyme inhibitor dipheyleneiodonium. Growth responses to fetal bovine serum and superoxide dismutase-inhibitable reduction of ferricytochrome c were not different between cultured tracheal myocytes from wild-type versus gp91 phagocyte oxidase null mice. These results suggest that mitogen stimulation of airway smooth muscle induces signal transduction of cell proliferation that is in part dependent on generation of partially reduced oxygen species, generated by an NADH or NADPH oxidoreductase that is different from the oxidase in phagocytic cells.

Animals↗
PubMed1999

TNF-alpha and IL-1alpha induce heme oxygenase-1 via protein kinase C, Ca2+, and phospholipase A2 in endothelial cells.

Heme oxygenase-1 (HO-1), an enzyme important in protection against oxidant stress, is induced in human vascular endothelial cells by the cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-1alpha (IL-1alpha). However, the signaling mediators that regulate the induction are not known. This study examined the involvement of protein kinase C (PKC), phospholipase A2 (PLA2), calcium, and oxidants in cytokine induction of HO-1. Acute exposure to the PKC activator phorbol 12-myristate 13-acetate (PMA) stimulated HO-1 mRNA. However, prolonged exposure, which downregulates most PKC isoforms, blocked induction of HO-1 mRNA by IL-1alpha and TNF-alpha. Additionally, the phosphatase inhibitors okadaic acid and calyculin enhanced cytokine induction of HO-1. Mepacrine, a PLA2 inhibitor, prevented HO-1 induction by cytokine, suggesting a role for arachidonate, the product of PLA2 hydrolysis of phospholipids, in HO-1 expression. The intracellular calcium chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid acetoxymethyl ester (BAPTA-AM) blocked cytokine induction of HO-1. Paradoxically, the calcium ionophore A-23187 prevented HO-1 induction by cytokine but not by PMA. Finally, the oxidant scavenger N-acetylcysteine inhibited HO-1 induction by cytokines. These results demonstrate that TNF-alpha and IL-1alpha induction of HO-1 requires PKC-mediated phosphorylation and PLA2 activation as well as oxidant generation.

Acetylcysteine↗
PubMed1999

Role of a novel KCa opener in regulating K+ channels of hypoxic human pulmonary vascular cells.

Hypoxic pulmonary vasoconstriction (HPVC) is mediated, in part, via membrane depolarization and inhibition of K+ channels. We recently observed that the naturally occurring steroid dehydroepiandrosterone (DHEA) reversed and prevented HPVC in isolated perfused and ventilated ferret lungs. In the current study, we investigated the effects of DHEA on the major K+ channels of chronically hypoxic human pulmonary smooth-muscle cells (HPSMC). K+ channels were recorded by using the patch-clamp technique in whole-cell and single-channel configurations. Single-channel recordings were performed in inside-out and outside-out excised patches, and in intact HPSMC in cell-attached configuration. Using whole-cell current recording, chronic hypoxia decreased the high-amplitude, high-noise, and charybdotoxin-sensitive Ca2+-dependent K+ channels (KCa). DHEA reversed the effect of chronic hypoxia on KCa, but had no effect on the low-amplitude, low-noise, and 4-aminopyridine-sensitive delayed rectifying K+ channels. In the cell-attached configuration, chronic hypoxia caused a decrease in KCa sensitivity to membrane potential (Em). DHEA reversed the effect of hypoxia on KCa sensitivity to Em and caused a mean of 40-mV left shift in voltage-dependent activation of KCa. DHEA increased KCa activation from both sides of membrane patches of hypoxic HPSMC via a cyclic adenosine monophosphate- and cyclic guanosine monophosphate-independent pathway. We concluded that DHEA is a novel KCa opener of the human pulmonary vasculature.

4-Aminopyridine↗