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Y M Kim

Publications and source records attributed to Y M Kim.

At least 163 records · Page 9Linked to original sources
PubMed1998

Sequence of electron carriers in the process of methanol oxidation by a new obligate methylotrophic bacterium.

From pink soluble fractions prepared from cells cultured in a copper-free medium, active methanol dehydrogenase (MDH) and two soluble c-type cytochromes (c-I and c-II) were purified homogeneously. The green fractions from cells grown on a medium containing 1.0 mg/l of copper had inactive MDH, cytochrome c-II, and blue copper protein. The amount of copper retained in the blue copper protein increased with cultivation time. The oxidized blue copper protein was similar to the classical type I blue copper proteins since it had the novel absorption peak at 625 nm. However, when the blue protein was reduced with MDH or dithionite, it showed the same spectrum as ferrocytochrome c-I. The isoelectric points of cytochrome c-I, blue copper protein and cytochrome c-II were 9.08, 9.08 and 6.52, respectively. These results suggest that the identity of the purified blue copper protein is cytochrome c-I, and copper ions bind to the cytochrome as methanol is depleted in the culture medium. In addition, MDH activity was not detected at all in the methanol-depleted condition. The data suggest that blue copper protein acts as a negative regulator for MDH. The electrons were transferred as follows: MDH-->cytochrome c-II-->cytochrome c-I (blue copper protein). It was also revealed that the initial 'docking' of MDH and cytochrome c-II is accompanied by electrostatic interactions between lysine or arginine residues on the alpha-subunit of MDH and carboxyl groups on the cytochrome c-II.

Alcohol Oxidoreductases↗
PubMed1998

Cloning and nucleotide sequence of the DNA gyrase gyrA gene from Serratia marcescens and characterization of mutations in gyrA of quinolone-resistant clinical isolates.

The sequence of the DNA gyrase gyrA gene of Serratia marcescens ATCC 14756 was determined. An open reading frame of 2,640 nucleotides coding for a polypeptide with a calculated molecular mass of 97,460 was found, and its sequence complemented the sequence of an Escherichia coli gyrA temperature-sensitive mutation. Analysis of the PCR products of the quinolone resistance-determining regions of gyrA genes from six quinolone-resistant clinical isolates revealed a single amino acid substitution, Ser-83 to Arg or Asp-87 to Tyr, in all six mutants, suggesting that a mutational alteration in gyrA is a common mechanism of quinolone resistance in S. marcescens.

4-Quinolones↗
PubMed1998

Cloning and expression of the gene for the Na+-coupled serine transporter from Escherichia coli and characteristics of the transporter.

We cloned a gene (sstT) for the Na+/serine symporter from the chromosome of Escherichia coli by using a low-copy-number vector and sequenced it. According to the deduced amino acid sequence, the transporter (SstT) consists of 414 amino acid residues. Hydropathy analysis suggested that the SstT protein possesses 9, instead of 12, hydrophobic domains.

Amino Acid Transport Systems↗
PubMed1998

Nitric oxide inhibits lipopolysaccharide-induced apoptosis in pulmonary artery endothelial cells.

Our group recently reported that cultured sheep pulmonary artery endothelial cells (SPAECs) became resistant to lipopolysaccharide (LPS)-induced apoptosis several days after constitutive synthesis of nitric oxide (NO) after adenoviral (Ad) transfer of inducible NO synthase (iNOS) or exposure to the NO donor S-nitroso-N-acetylpenicillamine (SNAP) (E. Tzeng, Y.-M. Kim, B. R. Pitt, A. Lizonova, I. Kovesdi, and T. R. Billiar. Surgery 122: 255-263, 1997). In the present study, we confirmed this observation by establishing stable transfectants after retroviral gene transfer [replication-deficient retrovirus (DFG)] of human iNOS (DFG-iNOS) SPAECs and then used all three approaches (Ad, DFG, and SNAP) to determine underlying mechanisms of this phenomenon. Continuous endogenous production of NO in itself did not cause apoptosis as assessed by phase-contrast microscopy, nuclear morphology, and internucleosomal DNA fragmentation. Prolonged (72-96 h) synthesis of NO, however, after DFG- or replication-deficient adenovirus (Ad. CMV)-iNOS or SNAP (100 microM, 96 h) inhibited LPS-induced apoptosis. The kinetics of such protection suggested that NO may be inducing other gene products. Ad-mediated transfer of manganese superoxide dismutase (MnSOD) decreased the sensitivity of wild-type SPAECs to LPS-induced apoptosis. MnSOD, however, was not induced in an NG-monomethyl-L-arginine (L-NMMA)-sensitive time-dependent fashion after Ad.CMV-iNOS. Other inducible genes that may be affected by NO and that may protect against potential oxidant-mediated LPS-induced apoptosis including 70-kDa heat shock protein, heme oxygenase-1, metallothionein, and Bcl-2 also were not elevated in an L-NMMA-sensitive, time-dependent fashion. Although the candidate gene product underlying NO-induced protection remains unclear, we did note that prolonged synthesis of NO inhibited LPS-induced activation of an interleukin-1beta-converting enzyme-like cysteine protease (cysteine protease protein-32-like) in a dithiothreitol-sensitive fashion, suggesting that S-nitrosylation of an important downstream target of convergence of apoptotic signals may contribute to the sensitivity of SPAECs to LPS.

Adenoviridae↗
PubMed1998

Functional differences between the two bellies of the cricothyroid muscle.

The contraction of the cricothyroid (CT) muscle, which results in a decrease in the distance between the thyroid and cricoid cartilages, is considered to be the main factor in lengthening the vocal folds. This is achieved by rotation of the CT joint. The CT muscle is composed of two distinct bellies, the pars recta and the pars obliqua. The function of each subunit is not clearly understood, although it is believed that they act differently because their fibers run in different directions. To clarify the function of the two bellies in phonation, the fundamental frequency (F0), vocal intensity, subglottic pressure, vocal fold length, and CT distance were measured using an in vivo canine laryngeal model. On the basis of these measurements, we demonstrated that the two bellies are varied in their effect on raising the pitch, rotation, and forward translation of the CT joint. The stimulation of the pars recta nerve resulted in a greater increase in the F0 value compared with that of pars obliqua. The combined activity of the pars recta and pars obliqua is important in adjustment of the vocal fold length. The CT approximations directed parallel to the pars recta and pars obliqua simultaneously were more effective in elevation of the pitch than the approximation placed parallel to the pars recta only. This finding may be clinically significant with regard to CT approximation thyroplasty in human trails.

Analysis of Variance↗
PubMed1998

Estimation of the extent of osteonecrosis of the femoral head using MRI.

The extent of necrosis is the main determining factor in the outcome of osteonecrosis of the femoral head and is best measured by MRI. Using statistical analyses, we have evaluated the accuracy and repeatability of seven different methods of measuring the extent of necrosis, of which three demonstrate good or acceptable accuracy. For the general observer their repeatability is poor; only for experienced observers were they reasonable. We conclude that within an institution or for personal use, the accuracy of some methods is acceptable, and repeatability reasonable. None is appropriate for international use.

Adult↗
PubMed1998

Inhibition of protein synthesis by nitric oxide correlates with cytostatic activity: nitric oxide induces phosphorylation of initiation factor eIF-2 alpha.

BACKGROUND: Nitric oxide (NO) is cytostatic for proliferating cells, inhibits microbial growth, and down-regulates the synthesis of specific proteins. Studies were undertaken to determine the mechanism by which NO inhibits total protein synthesis and whether the inhibition correlates with established cytostatic activities of NO. MATERIALS AND METHODS: In in vitro experiments, various cell types were exposed to NO using either donors or expression of inducible NO synthase (iNOS). The capacity of NO to suppress total protein synthesis, measured by incorporation of 35S-methionine into protein, was correlated with the capacity of NO to suppress cell proliferation, viral replication, or iNOS expression. Phosphorylation of eIF-2 alpha was examined as a possible mechanism for the suppressed protein synthesis by NO. RESULTS: Both NO donors and expression of the iNOS suppressed total protein synthesis in L929 cells and A2008 human ovarian tumor cells in parallel with decreased cell proliferation. Suppressed protein synthesis was also shown to correlate with decreased vaccinia virus proliferation in murine peritoneal macrophages in an iNOS-dependent manner. Furthermore, iNOS expression in pancreatic islets or RAW264.7 cells almost completely inhibited total protein synthesis, suggesting that nonspecific inhibition of protein synthesis may be the mechanism by which NO inhibited the synthesis of specific proteins such as insulin or iNOS itself. This possibility was confirmed in RAW264.7 cells where the inhibition of total protein synthesis correlated with the decreased iNOS protein. The decrease in protein levels occurred without changes in iNOS mRNA levels, implicating an inhibition of translation. Mechanistic studies revealed that iNOS expression in RAW264.7 cells resulted in the phosphorylation of eIF-2 alpha and inhibition of the 80S ribosomal complex formation. CONCLUSIONS: These results suggest that NO suppresses protein synthesis by stimulating the phosphorylation of eIF-2 alpha. Furthermore, our observations indicate that nonspecific inhibition of protein synthesis may be a generalized response of cells exposed to high levels of NO and that inhibition of protein synthesis may contribute to many of the described cytostatic actions of NO.

Animals↗
PubMed1998

Adenovirus-mediated inducible nitric oxide synthase gene transfer inhibits hepatocyte apoptosis.

BACKGROUND: Apoptosis limits hepatocyte viability in bioartificial livers in vitro and may contribute to liver dysfunction in vivo. Nitric oxide (NO) inhibits hepatocyte apoptosis; however, methods to deliver NO in a sustained manner to hepatocytes are limited. Here, we tested the feasibility of inducible NO synthase (iNOS) gene transfer as an approach to deliver an intracellular source of NO to inhibit spontaneous and tumor necrosis factor-alpha (TNF-alpha)-induced apoptosis in cultured hepatocytes. METHODS: An adenoviral vector carrying the human iNOS gene (AdiNOS) was used to overexpress iNOS in cultured rat hepatocytes. Spontaneous apoptosis was induced by prolonged culture (4 days), and stimulated apoptosis was induced by exposure to TNF-alpha + actinomycin D (TNF-alpha ActD). Nitrite (NO2-), cell viability, and cellular caspase-3-like protease activity were measured. RESULTS: AdiNOS gene transfer resulted in sustained NO production and protected hepatocytes from spontaneous and TNF-alpha + ActD-induced apoptosis. Apoptosis was associated with increases in caspase-3-like protease activity, which was suppressed by iNOS gene transfer in an NO-dependent manner. Dithiothreitol partially reversed the NO-induced suppression of caspase-3-like activity, which is consistent with S-nitrosylation of caspase-3. CONCLUSIONS: Adenovirus-mediated iNOS gene transfer effectively blocks spontaneous and TNF-alpha + ActD-induced cell killing in hepatocytes. iNOS gene transfer could be used to suppress apoptotic hepatocyte death in vitro and possibly in vivo.

Adenoviridae↗
PubMed1998

Biodistribution and kinetics of holmium-166-chitosan complex (DW-166HC) in rats and mice.

UNLABELLED: The fate of 166Ho-chitosan complex, a radiopharmaceutical drug for cancer therapy, was determined by studying its absorption, distribution and excretion in rats and mice. METHODS: Holmium-166-chitosan complex [0.75 mg of Ho(NO3)3 x 5H2O and 1 mg chitosan/ head] was administered intrahepatically to male rats. Radioactive concentrations in blood, urinary and fecal excretion and radioactive distribution in tissues were examined. To determine the effects of chitosan in 166Ho-chitosan complex, 166Ho alone [0.75 mg of Ho(NO3)3 x 5H2O/head] was intrahepatically administered to male rats, and radioactive concentrations in blood, urinary and fecal excretion and radioactive distribution were examined. In B16 melanoma-transplanted nude mice, radioactive distribution after intratumoral administration of 166Ho-chitosan complex [0.075 mg of Ho(NO3)3 x 5H2O and 0.10 mg chitosan/head] was investigated also. RESULTS: After administration of 166Ho-chitosan complex, the radioactive concentrations in blood were low, and cumulative urinary and fecal excretions over a period of 0-72 hr were 0.53% and 0.54%, respectively. The radioactive concentrations in tissues and the whole-body autoradiography images showed that most of the administered radioactivity was localized at the administration site, and only slight radioactivity was detected from the liver, spleen, lungs and bones. On the other hand, results of intrahepatic administration of 166Ho alone showed high radioactive concentrations in the blood, and the whole-body autoradiographs showed that the administered radioactivity was distributed in many organs and tissues. These results strongly suggest that 166Ho is retained at the administration site only when it forms a chelate complex with chitosan. Autoradiographs after intratumoral administration of 166Ho-chitosan complex showed that radioactivity was localized at the site of administration without distribution to the other organs and tissues. CONCLUSION: Administered 166Ho-chitosan complex is retained at the administration site after either intrahepatic or intratumoral administration to rats or tumor-transplanted nude mice.

Animals↗
PubMed1997

Purification and characterization of a manganese-containing superoxide dismutase from a carboxydobacterium, Pseudomonas carboxydohydrogena.

Superoxide dismutase from Pseudomonas carboxydohydrogena, a carboxydobacterium, grown on carbon monoxide was purified 37.6-fold in seven steps to homogeneity, with a yield of 1.4%. The final specific activity was 2,396 units per mg protein as determined by an assay based on a 50% decrease in the rate of cytochrome c reduction. The molecular weight of the native enzyme was determined to be 42,500. Sodium dodecyl sulfate gel electrophoresis revealed two identical subunits of molecular weight 21,700. The optimal pH for enzyme activity was found to be 9.0. The enzyme was stable to heat treatment. The isoelectric point of the native enzyme was found to be 7.1. The enzyme showed an absorption peak at 280 nm with a shoulder at around 289 nm. Sodium azide, but not sodium cyanide and hydrogen peroxide, was found to inhibit the enzyme activity. One mol of native enzyme was found to contain 1.09 g-atom of manganese. Analysis of amino acid composition revealed that the enzyme contains cysteine. The superoxide dismutase of P. carboxydohydrogena was found to have antigenic sites identical to those of Oligotropha carboxydovorans. The enzyme showed partial identity to Hydrogenophaga pseudoflava and Escherichia coli enzymes, but no identity to Acinetobacter sp. strain JC1 enzyme.

Amino Acids↗
PubMed1997

Nitric oxide inhibits apoptosis by preventing increases in caspase-3-like activity via two distinct mechanisms.

Nitric oxide (NO) has emerged as an important endogenous inhibitor of apoptosis, and here we report that NO prevents hepatocyte apoptosis initiated by the removal of growth factors or exposure to TNFalpha or anti-Fas antibody. We postulated that the mechanism of the inhibition of apoptosis by NO would include an effect on caspase-3-like protease activity. Caspase-3-like activity increased coincident with apoptosis due to all three stimuli, and treatment with the caspase-3-like protease inhibitor N-acetyl-Asp-Glu-Val-Asp-aldehyde inhibited both proteolytic activity and apoptosis. Endogenous or exogenous sources of NO prevented the increase in caspase-3-like activity in hepatocytes. Exposure of purified recombinant caspase-3 to an NO or NO+ donor inhibited proteolytic activity. Dithiothreitol (DTT), but not glutathione, reversed the inhibition of recombinant caspase-3 by NO. When lysates from cells stimulated to express inducible NO synthase or cells exposed to NO donors were incubated in DTT, caspase-3-like activity increased to about 55% of cells not exposed to a source of NO. Similarly, administration of an NO donor to rats treated with TNFalpha and D-galactosamine also prevented the increase in caspase-3-like activity as measured in liver homogenates. The effect of the NO donor was reversed by about 50% if the homogenate was incubated with DTT. TNFalpha-induced apoptosis and caspase-3-like activity were also reduced in cultured hepatocytes exposed to 8-bromo-cGMP, and both effects were inhibited by the cGMP-dependent kinase inhibitor KT5823. The suppression in caspase-3-like activity in hepatocytes exposed to an NO donor was partially blocked by an inhibitor of soluble guanylyl cyclase, 1H-[1,2,4]oxadiazolo[4,3, -a]quinoxalin-1-one, (ODQ), while the incubation of these lysates in DTT almost completely restored caspase-3-like activity to the level of TNFalpha-treated controls. These data indicate that NO prevents apoptosis in hepatocytes by either directly or indirectly inhibiting caspase-3-like activation via a cGMP-dependent mechanism and by direct inhibition of caspase-3-like activity through protein S-nitrosylation.

Animals↗
PubMed1997

Nitric oxide reversibly inhibits seven members of the caspase family via S-nitrosylation.

The caspases are a family of at least 10 human cysteine proteases that participate in cytokine maturation and in apoptotic signal transduction and execution mechanisms. Peptidic inhibitors of these enzymes are capable of blocking cytokine maturation and apoptosis, demonstrating their crucial roles in these processes. We have recently discovered that nitric oxide (NO), produced either extracellularly by NO donors or intracellularly by the inducible nitric oxide synthase, prevented apoptosis in hepatocytes. Caspase-3-like activity was found to be inhibited under these conditions. To investigate further the interaction between NO and caspases, we utilized purified human recombinant caspases and examined the effect of NO on enzymatic activities of different caspases. We report here that of the seven caspases studied, all were reversibly inhibited by NO. Dithiothreitol was able to reverse the NO inhibition, indicating direct S-nitrosylation of caspase catalytic cysteine residue by NO. Our results support the concept that NO is an endogenous regulator of caspase activity.

Animals↗
PubMed1997

Rare variants of divided right ventricle with sequestered apical trabecular component.

The right ventricle may be divided into two or more compartments by various structures in various ways. Rarely, the apical trabecular component may be sequestered from the rest of the right ventricle. We report 4 cases with different underlying lesions that share a common pathology of apical sequestration of the right ventricle resulting in diverse hemodynamic consequences. Case 1 had pulmonary valve stenosis. The apical sequestration of the right ventricle resulted in no significant hemodynamic consequence. Case 2 had multiple defects in the muscular ventricular septum. The volume of left-to-right shunt seemed to be reduced because of the commitment of some of the defects to the sequestered cavity. Case 3 had a large defect in the trabecular septum. As the defect involved the whole septum that was related to the sequestered right ventricular apex, the left ventricle together with the sequestered right ventricle formed a boot-shaped chamber. Hemodynamically, the muscular shelf was an interventricular septum. Case 4 had a coronary artery fistula to an isolated cavity that occupied the apical region of the right ventricle. The pathology was similar to the case that was reported as a five-chambered heart. The abnormal cavity was, in fact, the sequestered right ventricular apex.

Adolescent↗
PubMed1997

Upstream NF-kappaB site is required for the maximal expression of mouse inducible nitric oxide synthase gene in interferon-gamma plus lipopolysaccharide-induced RAW 264.7 macrophages.

Transient transfection assays with various deletion mutants of the mouse inducible nitric oxide synthase (iNOS) promoter linked to a CAT reporter gene demonstrated that, besides the downstream NF-kappaB site, the region from -973 to -925 which contains a potential binding site for NF-kappaB (upstream NF-kappaB site) also mediated lipopolysaccharide (LPS)-inducibility in mouse macrophage cell line RAW 264.7. Site-specific mutation of three conserved nucleotides within the upstream NF-kappaB site abolished additional induction by LPS as well as maximal expression of iNOS by IFN-gamma plus LPS. In contrast, site-specific mutation of the downstream NF-kappaB site caused almost all reduction in expression of the reporter gene by LPS or LPS plus IFN-gamma. Electrophoretic mobility shift assays with the two NF-kappaB sites showed LPS-induced NF-kappaB binding to both probes and its higher affinity to the upstream NF-kappaB site. Taken together, these suggest that the upstream NF-kappaB site having enhancer function, besides the downstream NF-kappaB site as a core promoter, is essential for maximal expression of the iNOS gene.

Animals↗
PubMed1997

Purification and some properties of ribulose 1,5-bisphosphate carboxylases/oxygenases from Acinetobacter sp. strain JC1 and Hydrogenophaga pseudoflava.

Ribulose 1,5-bisphosphate carboxylases/oxygenases (RuBisCOs) of two carboxydobacteria, Acinetobacter sp. strain JC1 and Hydrogenophaga pseudoflava, grown on carbon monoxide were purified and partially characterized. RuBisCO of Acinetobacter sp. JC1 was purified 5-fold in eight steps to homogeneity, with a yield of 1.6%. The final specific activity of the purified enzyme was 39.5 nmol CO2 incorporated per min per mg protein. The molecular weight of the native enzyme was determined to be 520,000. Sodium dodecyl sulfate-gel electrophoresis revealed two nonidentical subunits of molecular weights 53,500 and 15,000. The Km and Vmax for CO2 were 36.7 microM and 296.1 nmol per min per mg protein, respectively, and those for ribulose 1,5-bisphosphate were 3.7 microM and 770 nmol per min per mg protein, respectively. The enzyme of H. pseudoflava was purified 55-fold in eight steps to homogeneity, with a yield of 3.6%. The final specific activity was 304.3 nmol CO2 incorporated per min per mg protein. The molecular weight of the enzyme was estimated to be 505,000. The enzyme was found to have two kinds of nonidentical subunits of molecular weights 51,500 and 14,000. The Km and Vmax for CO2 were found to be 16.4 microM and 777.8 nmol per min per mg protein, respectively, and those for ribulose 1,5-bisphosphate were 0.1 microM and 436.2 nmol per min per mg protein, respectively. The N-terminal amino acid sequences of the large and small subunits of Acinetobacter sp. JC1 enzyme were Ala-Asp-Arg-Trp-Asn-Ala-Gly-Val-IIe-Pro-Tyr-Ala-Glu-Met-Gly and Met-Arg-Ile-Thr-Glu-Gly-Thr-Phe-Ser-Tyr-Leu-Pro-Asp-Phe-Thr, respectively. The sequences of the H. pseudoflava enzyme were Ala-Thr-Lys-Thr-Tyr-Asu-Ala-Gly-Val-Lys-Glu-Tyr-Trp-Ser-Thr and Met-Ser-Met-Gln-Asp-Tyr-His-Ser-Arg-Leu-Ser-Asp-Pro-Ala-Ile, respectively. The peptide map of RuBisCO from Acinetobacter sp. JC1 grown on carbon monoxide was different from that of the bacterium grown on methanol. The two RuBisCOs, however, were found to be identical in N-terminal residue and antigenic property. The RuBisCO of Acinetobacter sp. JC1 was found to share no immunological properties with those of H. pseudoflava, Oligotropha carboxidovorans and Pseudomonas carboxydohydrogena.

Acinetobacter↗
PubMed1997

Targeting nitric oxide (NO) delivery in vivo. Design of a liver-selective NO donor prodrug that blocks tumor necrosis factor-alpha-induced apoptosis and toxicity in the liver.

We have designed a drug that protects the liver from apoptotic cell death by organ-selective pharmacological generation of the bioregulatory agent, nitric oxide (NO). The discovery strategy involved three steps: identifying a diazeniumdiolate ion (R2N[N(O)NO]-, where R2N = pyrrolidinyl) that spontaneously decomposes to NO with a very short half-life (3 s) at physiological pH; converting this ion to a series of potential prodrug derivatives by covalent attachment of protecting groups that we postulated might be rapidly removed by enzymes prevalent in the liver; and screening the prodrug candidates in vitro and in vivo to select a lead and to confirm the desired activity. Of five cell types examined, only cultured hepatocytes metabolized O2-vinyl 1-(pyrrolidin-1-yl)diazen-1-ium-1,2-diolate (V-PYRRO/NO) to NO, triggering cyclic guanosine 3',5'-monophosphate (cGMP) synthesis and protecting the hepatocytes from apoptotic cell death induced by treatment with tumor necrosis factor-alpha (TNF alpha) plus actinomycin D. In vivo, V-PYRRO/NO increased liver cGMP levels while minimally affecting systemic hemodynamics, protecting rats dosed with TNF alpha plus galactosamine from apoptosis and hepatotoxicity. The results illustrate the potential utility of diazeniumdiolates for targeting NO delivery in vivo and suggest a possible therapeutic strategy for hepatic disorders such as fulminant liver failure.

Animals↗
PubMed1997

Nitric oxide protects cultured rat hepatocytes from tumor necrosis factor-alpha-induced apoptosis by inducing heat shock protein 70 expression.

Nitric oxide (NO) and tumor necrosis factor-alpha (TNFalpha) play important roles in the pathogenesis of liver disease during acute inflammation. The present study was designed to elucidate the effect of NO pre-exposure on TNFalpha-induced hepatotoxicity. Pretreatment of primary cultures of rat hepatocytes with the NO donor S-nitroso-N-acetylpenicillamine (SNAP) induced the expression of heat shock protein 70 (HSP70) mRNA and protein, which was associated with thermotolerance and cytoprotection from TNFalpha+actinomycin D-induced hepatotoxicity and apoptosis. SNAP transiently changed the intracellular redox state by inducing glutathione (GSH) oxidation associated with the formation of S-nitrosoglutathione (GSNO). HSP70 mRNA was also induced by the GSH-oxidizing agent diamide and the GSH-conjugating agent N-ethylmaleimide, suggesting that NO induces HSP70 expression through GSH oxidation. The protective effect of SNAP pretreatment on TNFalpha-induced apoptosis correlated with the level of HSP70 expression. SNAP pretreatment inhibited reactive oxygen intermediate generation and lipid peroxidation effects that were reversed by blocking HSP70 expression using an antisense oligonucleotide to HSP70. Finally, endogenous NO formation, induced in hepatocytes stimulated with interferon-gamma and interleukin-1beta, led to the formation of GSNO and GSSG, induced HSP70, and attenuated TNFalpha-mediated cytotoxicity. These findings demonstrated that NO can induce resistance to TNFalpha-induced hepatotoxicity, possibly through the stimulation of HSP70 expression.

Animals↗