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J R Hoidal

Publications and source records attributed to J R Hoidal.

At least 37 records · Page 2Linked to original sources
PubMed1998

Effect of tumor necrosis factor-alpha and interleukin-1 alpha on heme oxygenase-1 expression in human endothelial cells.

Heme iron exacerbates oxidant damage by catalyzing the production of free radicals. Heme oxygenase is the rate-limiting enzyme involved in heme catabolism. An inducible form of heme oxygenase, heme oxygenase-1 (HO-1), is upregulated in oxidant and inflammatory settings, and recent work suggests that HO-1 induction may serve a protective function against oxidant injury. The ability of the endogenous inflammatory mediators, interleukin (IL)-1 alpha, tumor necrosis factor-alpha (TNF-alpha), and IL-6, to enhance HO-1 expression in cultured human endothelial cells was examined in this study. HO-1 mRNA and protein expression were upregulated by IL-1 alpha and TNF-alpha exposure but not by IL-6. Induction of HO-1 mRNA by IL-1 alpha and TNF-alpha occurred in a concentration- and time-dependent fashion, with maximal expression occurring by 4 h for both cytokines. Induction depended on protein synthesis and occurred at the transcriptional level. Inhibition of the AP-1 transcription factor with curcumin decreased the cytokine induction of HO-1 mRNA, suggesting the involvement of this transcription factor in cytokine signaling of HO-1. The results of this study indicate that the endogenous inflammatory cytokines IL-1 alpha and TNF-alpha induce HO-1 in endothelial cells, providing further evidence that HO-1 may be an important cellular response to inflammatory stress.

Blotting, Western↗
PubMed1998

Effect of dehydroepiandrosterone on hypoxic pulmonary vasoconstriction: a Ca(2+)-activated K(+)-channel opener.

In the present study, we investigated the effects of the naturally occurring hormone dehydroepiandrosterone (DHEA) on hypoxic pulmonary vasoconstriction (HPVC) in isolated ferret lungs and on K+ currents in isolated and cultured ferret pulmonary arterial smooth muscle cells (FPSMCs). Severe alveolar hypoxia (3% O2-5% CO2-92% N2) caused an initial increase in pulmonary arterial pressure (Ppa) that was followed by a reversal in pulmonary hypertension. Maintaining alveolar hypoxia caused a sustained secondary increase in Ppa. Pretreating the lungs with the K(+)-channel inhibitor tetraethylammonium (TEA) caused a small increase in baseline Ppa, potentiated HPVC, and prevented the reversal of HPVC during the sustained alveolar hypoxia. Treating the lungs with DHEA caused a near-complete reversal of HPVC in control lungs and in lungs that were pretreated with TEA. DHEA also reversed the KCl-induced increase in Ppa. In FPSMCs, DHEA caused an adenosine 3',5'-cyclic monophosphate- and guanosine 3',5'-cyclic monophosphate-independent increase in activity of the Ca(2+)-activated K+ (KCa) current. In a cell-attached configuration, DHEA caused a mean shift of -22 mV in the voltage-dependent activation of the KCa channel. We conclude that DHEA is a novel KCa-channel opener of the pulmonary vasculature.

Animals↗
PubMed1998

ET-1 modulates KCa-channel activity and arterial tension in normoxic and hypoxic human pulmonary vasculature.

The molecular mechanisms by which endothelin (ET)-1 induces pulmonary hypertension are poorly understood. We investigated the effects of ET-1 on outward K+ currents of normoxic and chronically hypoxic human pulmonary arterial (PA) smooth muscle cells (HPSMCs). In normoxic HPSMCs, ET-1 has dual effects. In intact cells, 5 nM ET-1 activates the large-conductance and Ca2+-activated K+ (KCa)-channel current [IK(Ca)] by increasing intracellular Ca2+ concentration, whereas it directly inhibits IK(Ca) in isolated membrane patches. At a higher concentration (10 nM), ET-1-induced IK(Ca) inhibition predominates. In hypoxic HPSMCs, ET-1 at 5 nM significantly reduces IK(Ca). The ETA-receptor antagonist BQ-123 reverses the ET-1-induced decrease in IK(Ca). Chronic BQ-123 treatment also prevents the hypoxia-induced decrease in IK(Ca). In PA rings obtained from human organ donors, ET-1 causes a concentration-dependent increase in tension. The ET-1-mediated increase in tension is reversed by a KCa-channel agonist. The increase in tension at the highest concentration studied (9 nM) was more pronounced in PA rings obtained from patients with chronic obstructive pulmonary disease. These results imply that an ET-1-induced decrease in IK(Ca) contributes to chronic hypoxia-induced pulmonary hypertension.

4-Aminopyridine↗
PubMed1998

Characterization and localization of the genes for mouse proteinase-3 (Prtn3) and neutrophil elastase (Ela2).

Proteinase-3 (PR-3) and neutrophil elastase (NE) are polymorphonuclear leukocyte serine proteinases that degrade extracellular matrix proteins including elastin and appear to be involved in the pathogenesis of several diseases characterized by tissue destruction most notably emphysema and Wegener's granulomatosis. In this report we characterize and compare the mouse PR-3 and NE genes and establish by FISH analysis a common location on mouse chromosome 10C2. Each gene consists of five exons and four introns conserving the typical granule-associated serine proteinase gene structure. The mouse PR-3 gene (Prtn3) is approximately 3.7 kb and is within 2.2 kb of the smaller (1.7 kb) NE gene (Ela2). The larger size of Prtn3 is accounted for by differences in intron sizes. A comparison between the mouse and human PR-3 cDNA reveals 73% homology, however, this drops to 60% when the amino acid sequences are compared. Homology between the mouse and human NE cDNA is 77% for both the cDNA and amino acid sequences. The catalytic triad and its placement are conserved among the four genes. The proximal promoter of mouse Prtn3 contains a TATA box, c-myb and an ets transcriptional site. As these are functional elements in the mouse Ela2 promoter they may also be important in the expression of Prtn3.

Animals↗
PubMed1998

Copper-dependent inflammation and nuclear factor-kappaB activation by particulate air pollution.

Particulate air pollution causes increased cardiopulmonary morbidity and mortality, but the chemical determinants responsible for its biologic effects are not understood. We studied the effect of total suspended particulates collected in Provo, Utah, an area where an increase in respiratory symptoms in relation to levels of particulate pollution has been well documented. Provo particulates caused cytokine-induced neutrophil chemoattractant-dependent inflammation of rat lungs. Provo particulates stimulated interleukin-6 (IL-6) and IL-8 production, increased IL-8 messenger RNA (mRNA) and enhanced expression of intercellular adhesion molecule-1 (ICAM-1) in cultured BEAS-2B cells, and stimulated IL-8 secretion in primary cultures of human bronchial epithelium. Cytokine secretion was preceded by activation of the transcription factor nuclear factor-kappaB (NF-kappaB) and was reduced by treatment of cultures with superoxide dismutase, deferoxamine, or N-acetylcysteine. These biologic effects were replicated by culturing BEAS cells with quantities of Cu2+ found in Provo extract. IL-8 secretion by BEAS cells could be modified by addition of normal constituents of airway lining fluid to the culture medium. Mucin significantly reduced IL-8 secretion, and ceruloplasmin significantly increased IL-8 secretion and activation of NF-kappaB. These findings suggest that copper ions may cause some of the biologic effects of inhaled particulate air pollution in the Provo region of the United States, and may provide an explanation for the sensitivity of asthmatic individuals to Provo particulates that has been observed in epidemiologic studies.

Air Pollution↗
PubMed1998

Lung injury and oxidoreductases.

Acute lung injury represents a wide spectrum of pathologic processes, the most severe end of the spectrum being the acute respiratory distress syndrome. Reactive oxygen intermediates have been implicated as important in the pathobiochemistry of acute lung injury. The endogenous sources that contribute to the generation of reactive oxygen intermediates in acute lung injury are poorly defined but probably include the molybdenum hydroxylases, NAD(P)H oxidoreductases, the mitochondrial electron transport chain, and arachidonic acid-metabolizing enzymes. Our laboratory has focused, in particular, on the regulation of two of these enzyme systems, xanthine oxidoreductase (XDH/XO) and NAD(P)H oxidase. We observe that gene expression of XDH/XO is regulatory in a cell-specific manner and is markedly affected by inflammatory cytokines, steroids, and physiologic events such as hypoxia. Posttranslational processing is also important in regulating XDH/XO activity. More recently, the laboratory has characterized an NAD(P)H oxidase in vascular cells. The cytochrome components of the oxidase, gp91 and p22, appear similar to the components present in phagocytic cells that contribute to their respiratory burst. In human vascular endothelial and smooth muscle cells, oncostatin M potently induces gp91 expression. We believe that regulation of gp91 is a central controlling factor in expression of the vascular NAD(P)H oxidase. In summary, the studies support the concept that the oxidoreductases of vascular cells are expressed in a highly regulated and self-specific fashion.

Animals↗
PubMed1998

Radiation therapy for tracheobronchial amyloidosis.

A 67-year-old man presented with localized tracheobronchial amyloidosis involving the distal trachea and the right-sided airways. The disease caused right middle lobe collapse and threatened the right upper and lower lobes. A variety of bronchoscopic methods, including Nd:YAG laser resection, dilation, and stenting, were used as temporizing methods. External beam radiation therapy, considered because of disease progression, caused a measurable local response. Radiation therapy should be considered as a treatment option for localized tracheobronchial amyloidosis causing airway obstruction.

Aged↗
PubMed1997

Human dipeptidyl-peptidase I. Gene characterization, localization, and expression.

Dipeptidyl-peptidase I, a lysosomal cysteine proteinase, is important in intracellular degradation of proteins and appears to be a central coordinator for activation of many serine proteinases in immune/inflammatory cells. Little is known about the molecular genetics of the enzyme. In the present investigation the gene for dipeptidyl-peptidase I was cloned and characterized. The gene spans approximately 3.5 kilobases and consists of two exons and one intron. The genomic organization is distinct from the complex structures of the other members of the papain-type cysteine proteinase family. By fluorescence in situ hybridization, the gene was mapped to chromosomal region 11q14.1-q14.3. Analysis of the sequenced 5'-flanking region revealed no classical TATA or CCAAT box in the GC-rich region upstream of cap site. A number of possible regulatory elements that could account for tissue-specific expression were identified. Northern analyses demonstrated that the dipeptidyl-peptidase I message is expressed at high levels in lung, kidney, and placenta, at moderate to low levels in many organs, and at barely detectable levels in the brain, suggesting tissue-specific regulation. Among immune/inflammatory cells, the message is expressed at high levels in polymorphonuclear leukocytes and alveolar macrophages and their precursor cells. Treatment of lymphocytes with interleukin-2 resulted in a significant increase in dipeptidyl-peptidase I mRNA levels, suggesting that this gene is subjected to transcriptional regulation. The results provide initial insights into the molecular basis for the regulation of human dipeptidyl-peptidase I.

Base Sequence↗
PubMed1997

Effect of chronic hypoxia on K+ channels: regulation in human pulmonary vascular smooth muscle cells.

We investigated the effects of chronic hypoxia on the major outward K+ currents in early cultured human main pulmonary arterial smooth muscle cells (HPSMC). Unitary currents were measured from inside-out, outside-out, and cell-attached patches of HPSMC. Chronic hypoxia depolarized resting membrane potential (Em) and reduced the activity of a charybdotoxin (CTX)- and iberiotoxin-sensitive, Ca2+-dependent K+ channel (KCa). The 4-aminopyridine-sensitive and CTX-insensitive channel or the delayed rectifier K+ channel was unaffected by chronic hypoxia. Chronic hypoxia caused a +33- to +53-mV right shift in voltage-dependent activation of K(Ca) and a decrease in K(Ca) activity at all cytosolic Ca2+ concentrations ([Ca2+]i) in the range of 0.1-10 microM. Thus the hypoxia-induced decrease in K(Ca) activity was most likely due to a decrease in K(Ca) sensitivity to Em and [Ca2+]i. Chronic hypoxia reduced the ability of nitric oxide (NO.) and guanosine 3',5'-cyclic monophosphate (cGMP) to activate K(Ca). The cGMP-dependent protein kinase-induced activation of K(Ca) was also significantly inhibited by chronic hypoxia. In addition, inhibiting channel dephosphorylation with calyculin A caused significantly less increase in K(Ca) activity in membrane patches excised from chronically hypoxic HPSMC compared with normoxic controls. This suggests that the mechanism by which hypoxia modulates NO.-induced K(Ca) activation is by decreasing the NO./cGMP-mediated phosphorylation of the channel.

Blood Vessels↗
PubMed1997

Induction of urokinase-type plasminogen activator receptor by IL-1 beta.

Extensive tissue remodeling occurs in survivors of acute lung injury, leading to nearly normal histology and physiology in the majority of individuals, whereas others suffer significant impairment due to the development of pulmonary fibrosis. Alveolar epithelial cells play a central role in the repair process. They are strategically located to directly participate in the solubilization of intraalveolar fibrin deposits, and have the capacity to promote fibrinolysis. We have previously reported that interleukin-1 beta (IL-1 beta), an important inflammatory mediator in acute lung injury, upregulates urokinase-type plasminogen activator expression by human A549 cells (1). In this work, we show that IL-1 beta increases cell-surface plasmin generation, mediated in part by increased expression of urokinase receptor (u-PAR). Northern blot analyses demonstrated that IL-1 beta rapidly induces accumulation of u-PAR messenger RNA (mRNA) in a dose-dependent fashion, and that this effect is blocked by actinomycin. The IL-1 beta-mediated increase in u-PAR mRNA is inhibited by: (1) the relatively specific protein kinase C (PKC) inhibitors 1-(5-isoquinoline sulfonyl)-2-methylpiperazine (H7) and calphostin C; and (2) prolonged pretreatment of cells with phorbol myristate acetate (PMA), suggesting that PKC is an important component of the signaling pathway. Okadaic acid, an inhibitor of serine/threonine phosphatases, markedly potentiates the effect of IL-1 beta on u-PAR mRNA levels. In contrast, dexamethasone, in concentrations as low as 10(-8) M, completely blocks the IL-1 beta-mediated increase in u-PAR mRNA. Half-life experiments show that dexamethasone has no effect on u-PAR mRNA stability. Aldosterone, at concentrations in which it binds primarily to the mineralocorticoid receptor, has no effect on u-PAR expression, suggesting that the glucocorticoid effect is due to a transrepressive mechanism. In summary, IL-1 beta increases cell-surface plasmin generation in A549 cells by coordinately upregulating urokinase and u-PAR expression. Transcriptional activation of the u-PAR gene involves PKC-dependent mechanisms, and glucocorticoid suppression is probably due to interactions between the glucocorticoid receptor and another transcriptional activating system such as activator protein-1 (AP-1) and/or nuclear factor-kB (NF-kB).

Blotting, Northern↗
PubMed1996

Human proteinase-3 expression is regulated by PU.1 in conjunction with a cytidine-rich element.

Human proteinase-3 is one of three serine proteinases present in the azurophil granules of polymorphonuclear leukocytes along with elastase and cathepsin G. Proteinase-3 gene expression is confined to the promyelocytic stage of polymorphonuclear leukocyte maturation. The present investigation identifies elements responsible for this highly controlled tissue- and developmental-specific expression of proteinase-3. Within the first 200 base pairs of the proteinase-3 promoter, two elements were identified as important for expression, these elements at -101 and -190 confer the majority of the activity. The element at -101 has a PU.1 consensus. It binds a myeloid nuclear protein of approximately 45 kDa that "supershifts" with PU.1 antibody and is competed by the CD11b PU.1 element. The element at -190 has a core sequence of CCCCGCCC (CG element). The cytidines but not the guanidine are essential for promoter activity. The CG element binds a second nuclear protein with a molecular mass of approximately 40 kDa that is found in cells of myeloid lineage as well as non-myeloid HeLa cells. However, the proteinase-3 promoter is not active in HeLa cells which suggests that the CG element alone is not sufficient for proteinase-3 gene expression. Maturation of promyelocytic cells results in an inhibition of proteinase-3 gene expression and a reduction in nuclear protein binding to the PU.1 and CG elements. Similar elements occur in the elastase and cathepsin G promoters. Using the elastase and cathepsin G PU.1 and CG-like elements as probes results in identical band-shift patterns to that obtained with proteinase-3 PU.1 and CG elements. These data suggest that there is cooperative interaction between a PU.1 and a CG element with a consensus of CCCCXCCC and that they are important control elements for tissue- and developmental-specific expression of azurophil serine proteinases of polymorphonuclear leukocytes.

Autoantigens↗
PubMed1996

Amino acid-derived phthalimide and saccharin derivatives as inhibitors of human leukocyte elastase, cathepsin G, and proteinase 3.

Amino acid-derived phthalimide and saccharin derivatives have been investigated for their inhibitory activity toward the serine proteinases human leukocyte elastase, cathepsin G, and proteinase 3. The saccharin derivatives were found to be effective time-dependent inhibitors of elastase and proteinase 3 (kobs/[I] values ranged between 180 and 3620 M-1 S-1) and showed weak or no inhibition toward cathepsin G. The corresponding phthalimide derivatives were found to be inactive.

Amino Acid Sequence↗
PubMed1996

Molecular cloning and characterization of the human xanthine dehydrogenase gene (XDH).

Xanthine dehydrogenase (XDH, EC 1.1.1.204) is a rate-limiting enzyme in the oxidative metabolism of purines and is thought to play a key role in a variety of pathophysiologic processes including ischemiasolidusreperfusion injury, viral pneumonia, and renal failure. We herein report the isolation and characterization of the human XDH gene. The gene is composed of 36 exons and 35 introns and spans at least 60 kb. The exon sizes range from 53 to 279 bp, and the intron sizes range from 0.2 to over 8 kb. Using primer extension and RNase protection analyses, two transcriptional initiation sites were identified 59 and 82 nucleotides upstream of the ATG start codon. One Goldberg-Hogness box (ATTTAT)-like sequence was found 24 bp upstream from the second transcriptional initiation site, and two inverted CCAAT sequences were found 19 and 42 bp upstream from the second transcriptional initiation sites. A relative GC-enriched region was found between -55 and -121. Approximately 2 kb of the 5'-flanking region was sequenced, and a variety of putative regulatory elements were identified including CsolidusEBP binding sites, IL-6 and NF-kappaB sites, and potential TNF-RE, IFN-gamma-RE, and IL-1-RE sites.

Base Sequence↗
PubMed1996

Biosynthesis and processing of proteinase 3 in U937 cells. Processing pathways are distinct from those of cathepsin G.

Proteinase 3 is a human polymorphonuclear leukocyte serine proteinase that degrades elastin in vitro and causes emphysema when administered by intratracheal insufflation into hamsters. Proteinase 3, stored in the azurophilic granules, is expressed in progenitor cells of myeloid origin. In the present study, the biosynthesis, processing, and intracellular transport of the enzyme was investigated in the human myelomonocytic cell line U937. Proteinase 3 is initially identified as a 35-kDa precursor and converted into the 29-kDa mature form within 3 h. By using a combination of techniques including amino-terminal sequencing, we identified the 35-kDa form as a zymogen containing an activation dipeptide but lacking the amino-terminal 25 residues, presumably the result of cleavage by a signal peptidase. Tunicamycin treatment and alkalinization of acidic cell compartments with NH4Cl did not prevent the processing of the proteinase 3 zymogen into the mature form, suggesting that the enzyme is targeted to the cytoplasmic granules by a mechanism other than the mannose 6-phosphate receptor. Brefeldin A inhibited the zymogen processing, suggesting that the dipeptide cleavage occurred in a post-Golgi organelle. The enzyme responsible for the removal of the dipeptide is a cysteine proteinase since E-64d, a class-specific inhibitor, prevented processing. However, treatment of cells with a dipeptidyl peptidase I inhibitor, Gly-Phe-diazomethyl ketone and with the lysosomotropic agents, NH4Cl and chloroquine, did not prevent dipeptide cleavage, indicating that the processing enzyme for proteinase 3 is not dipeptidyl peptidase I. In contrast, Gly-Phe-diazomethyl ketone inhibited cleavage of the dipeptide from cathepsin G. This indicates that processing of proteinase 3 is distinct from that of cathepsin G. Proteinase 3 is also processed at the COOH-terminal extension. Cleavage takes place next to Arg-222, suggesting that a trypsin-like proteinase is involved in the COOH-terminal processing.

Amino Acid Sequence↗
PubMed1996

Nitric oxide production during adjuvant-induced and collagen-induced arthritis.

OBJECTIVE: To investigate the role of nitric oxide (NO) production and NO synthase (NOS) induction during adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA) in Dark Agouti rats. METHODS: Urinary nitrate excretion and immune NOS (INOS) messenger RNA (mRNA) expression were measured in the joint, lymph node, spleen, and liver tissues following the induction of either AIA or CIA. RESULTS: Urinary nitrate excretion and iNOS mRNA expression increased substantially during joint inflammation in both models of arthritis. However, the increases in urinary nitrate excretion and iNOS mRNA expression observed in the joint, liver, and spleen tissues during AIA were greater than those observed during CIA, although iNOS induction in the lymph nodes was similar for both models. A prior injection with Mycobacterium bovis heat-shock protein resulted in suppression of arthritis and NO production in AIA, but not in CIA. CONCLUSION: Differences in NO production during AIA versus CIA are a reflection of the fundamental pathophysiologic differences between these 2 models of arthritis. Thus, NO production in these 2 models could not be merely a nonspecific reaction to the adjuvant injection, nor simply a byproduct of local inflammation in the joint.

Animals↗
PubMed1996

Nitric oxide donor prevents hydrogen peroxide-mediated endothelial cell injury.

Because nitric oxide is being used to treat acute lung injury and because it may either reduce or potentiate oxidant-mediated vascular injury, we studied the effect of the nitric oxide donor S-nitroso-N-acetyl-D-penicillamine (SNAP) on hydrogen peroxide (H2O2)-induced injury to cultured rat lung microvascular endothelial cells (RLMVC). Cells were exposed to H2O2 through its enzymatic generation by glucose and glucose oxidase or by its direct application. Glucose oxidase exposure causes a concentration- and time-dependent increase in 51chromium (51Cr) release from RLMVC. Catalase, dimethylthiourea or deferoxamine protects against this oxidant injury. SNAP (100 microM) prevents the increase in 51Cr release resulting from glucose oxidase or direct application of H2O2. N-acetyl-D-penicillamine is ineffective. Photo-decayed SNAP slightly decreases the 51Cr release caused by glucose oxidase but not the injury produced by directly adding H2O2. Treatment with the guanosine 3',5'-cyclic monophosphate (cGMP) analogue 8-BrcGMP (1-10 mM) provides no protection. SNAP decreases in vitro the net oxidation of ferrous to fcrric iron by H2O2, the iron-catalyzed consumption of H2O2 in Fenton's reaction, the iron-mediated generation of hydroxyl radicals, and the Fe(2+)-H2O2-catalyzed peroxidation of lipid membranes. Providing exogenous nitric oxide dramatically prevents H2O2-mediated endothelial injury, likely by reducing iron-mediated oxidant generation and subsequent lipid peroxidation.

Animals↗
PubMed1996

Regulation of xanthine dehydrogenase and xanthine oxidase activity by hypoxia.

The present study determined the effect of hypoxia on xanthine dehydrogenase (XDH) and xanthine oxidase (XO) activity and gene and protein expression in cultured bovine aortic endothelial cells (BAEC). BAEC were exposed to hypoxia (3% O2) or anoxia (0% O2) for 24 or 48 h and to 24 h of hypoxia followed by 24 h of reoxygenation. Hypoxia- and anoxia-exposed BAEC demonstrated a greater than twofold increase in XDH/XO activity at 24 and 48 h compared with timed controls. Hypoxic cells that were subsequently reoxygenated in 21% O2 also demonstrated a similar increase in XDH/XO activity vs. timed controls. No differences were seen in mRNA levels at any time point. Similarly, no difference was noted in XDH/XO protein expression after hypoxic exposure, as determined by Western blot analysis. The increase in XDH/XO activity was not prevented by cyclohexamide, indicating that protein synthesis was not required. Thus the increased XDH/XO activity observed in response to hypoxia in the present study was due to posttranslational modulation of the enzyme.

Animals↗