Biomedical subjects

T R Billiar

Publications and source records attributed to T R Billiar.

At least 199 records · Page 11Linked to original sources

PubMed1994

Molecular cloning, structure, and chromosomal localization of the human inducible nitric oxide synthase gene.

Nitric oxide, a multifunctional effector molecule synthesized by nitric oxide synthase (NOS) from L-arginine, conveys signals for vasorelaxation, neurotransmission, and cytotoxicity. Three different NOS isoforms have been identified which fall into two distinct types, constitutive and inducible. The inducible NOS (iNOS) isoform is expressed in a variety of cell types and tissues in response to inflammatory agents and cytokines. The human iNOS (NOS2) gene was isolated on overlapping cosmid clones from a human genomic library using both the murine macrophage and the human hepatocyte iNOS cDNAs as probes. All isolated cosmids were part of a single genomic locus and no other genomic loci were identified or isolated. Analysis of this locus indicated that the human iNOS gene is approximately 37 kilobases in length and consists of 26 exons and 25 introns. Primer extension analysis of lipopolysaccharide and cytokine-stimulated human hepatocyte RNA mapped the transcriptional initiation site 30 base pairs downstream of a TATA sequence, and a 400-base pair 5'-flanking region was found to be structurally similar to the recently described murine iNOS promoter. Polymerase chain reaction analysis of a human/rodent genomic DNA somatic cell hybrid panel and fluorescent in situ hybridization indicated that the human iNOS gene is located on chromosome 17 at position 17cen-q11.2.

Amino Acid Oxidoreductases↗

PubMed1994

Coinduction of nitric oxide synthase and argininosuccinate synthetase in a murine macrophage cell line. Implications for regulation of nitric oxide production.

In macrophages and other cell types, bacterial lipopolysaccharide and certain cytokines stimulate nitric oxide (NO) production via expression of the inducible isoform of nitric oxide synthase (NOS). Citrulline, which is the coproduct of NOS-catalyzed metabolism of arginine, can be recycled to arginine by the action of argininosuccinate synthetase and argininosuccinate lyase, which are present at high levels in hepatocytes and renal tubular cells but normally at very low levels in other cell types such as macrophages. The present study demonstrates that lipopolysaccharide and interferon-gamma, which induce NOS in the murine macrophage cell line RAW 264.7, also coinduce activity and mRNA for argininosuccinate synthetase, which is limiting for arginine synthesis. Argininosuccinate lyase activity and mRNA abundance are unaffected. Induction of argininosuccinate synthetase is not blocked by NG-monomethyl-L-arginine, a potent inhibitor of NOS, indicating that argininosuccinate synthetase induction is not the consequence of depleting cellular arginine levels by NOS. Because plasma levels of arginine are limiting for NO synthesis, enhanced cellular capacity to regenerate arginine from citrulline could play a significant role in regulating NO production, especially under conditions where the inducible isoform of NOS is expressed.

Amino Acid Oxidoreductases↗

PubMed1994

Efficacy of inhaled nitric oxide in a porcine model of adult respiratory distress syndrome.

OBJECTIVE: To assess the efficacy of inhaled nitric oxide (NO) in reducing pulmonary hypertension in a porcine model of adult respiratory distress syndrome. DESIGN: Nonrandomized, controlled experiment without blinding. SETTING: Surgical research laboratory. PARTICIPANTS: Twelve pigs, matched equally for body weight. INTERVENTION: Acute lung injury was induced by intravenous injection of oleic acid. Animals were then divided into either a control group, for monitoring without any further intervention, or a NO-treatment group, in which NO was administered at concentrations of 10 to 80 ppm, with each step separated by a NO-free interval to assess duration of effect. MAIN OUTCOME MEASURES: Pulmonary artery pressure, systemic blood pressure, PaO2, intrapulmonary shunt fraction, and extravascular lung water. Nitrosylated hemoglobin, arterial methemoglobin, and plasma nitrite and nitrate concentrations. RESULTS: All animals responded to oleic acid injection with rapid development of pulmonary hypertension and deterioration of PaO2 and intrapulmonary shunt fraction. Inhaled NO reversed these changes in a concentration-dependent manner. Cessation of NO administration led to a prompt return of pulmonary hypertension. A small but significant drop in systemic blood pressure was observed only at the highest concentration of NO administered (80 ppm). Extravascular lung water almost doubled following oleic acid injury. This increase was sustained in all animals for the remainder of the experiment. Significant increases in circulating methemoglobin and plasma nitrite and nitrate concentrations were measured during NO inhalation. CONCLUSION: Inhaled NO appears to be a selective pulmonary vasodilator and may prove to be useful in improving gas exchange in adult respiratory distress syndrome.

Administration, Inhalation↗

PubMed1994

Differential induction of nitric oxide synthase in hepatocytes during endotoxemia and the acute-phase response.

OBJECTIVE: Nitric oxide (NO) is a potent biologic mediator produced by hepatocytes following exposure to cytokines and lipopolysaccharide (LPS). These cytokines are also known to regulate induction of the hepatic acute-phase response. The objective of this study was to determine whether inducible nitric oxide synthase (iNOS), the enzyme that produces NO, is expressed as part of the hepatic acute-phase response. DESIGN: The gene expression for inducible NOS (iNOS) as well as alpha 1-acid glycoprotein (AGP), an established acute-phase reactant, was measured by Northern blot analysis in rat hepatocytes in vivo during endotoxemia (LPS injection) and during the acute-phase response produced by hindlimb turpentine injection. Hepatocyte iNOS messenger RNA (mRNA) levels were correlated with iNOS activity and circulating plasma nitrite and nitrate levels. In vitro, iNOS and AGP mRNA levels were determined in cultured hepatocytes stimulated with interleukin 6 (IL-6), interleukin 1 beta (IL-1 beta), tumor necrosis factor alpha (TNF-alpha), or dexamethasone. RESULTS: The AGP mRNA levels were increased in vivo following both LPS and turpentine injection, while iNOS expression was induced only by LPS injection. Hepatocyte iNOS activity and plasma nitrite and nitrate levels also increased after LPS treatment. In vitro, the cytokine combination IL-6, IL-1 beta, and TNF-alpha induced hepatocyte iNOS expression but had minimal effects on AGP in the absence of dexamethasone. Addition of dexamethasone alone markedly increased AGP mRNA levels, with further increases seen with TNF-alpha or IL-1 beta addition. In contrast, dexamethasone decreased iNOS expression. CONCLUSION: The results show that hepatocyte iNOS expression is not part of the acute-phase response induced by remote inflammation and indicates that iNOS is differentially regulated from the acute-phase reactant, AGP.

Acute-Phase Reaction↗

PubMed1994

Tumor necrosis factor-alpha regulates in vivo nitric oxide synthesis and induces liver injury during endotoxemia.

Tumor necrosis factor-alpha is a principal mediator of the pathophysiological effects of endotoxemia and endotoxin shock. Tumor necrosis factor-alpha also contributes to the stimulation of nitric oxide synthesis by the induction of the enzyme nitric oxide synthase in a variety of tissues. Although the importance of tumor necrosis factor-alpha in the induction of nitric oxide synthase activity in vitro is well known, its role in in vivo nitric oxide synthesis has not been convincingly established. We were interested in determining whether tumor necrosis factor-alpha plays a significant role in the in vivo induction of nitric oxide synthesis. In Corynebacterium parvum-primed mice, lipopolysaccharide injection resulted in elevated serum tumor necrosis factor-alpha levels early and increased hepatic enzyme release (641 +/- 80 IU AST/L; 22.7 +/- 1.9 IU ornithine carbamoyltransferase per liter) and plasma nitrite and nitrate (804 +/- 84 mumol/L) 5 hr after lipopolysaccharide injection. Polyclonal rabbit anti-mouse anti-tumor necrosis factor-alpha reduced in vivo tumor necrosis factor-alpha levels (1 hr, 7,332 +/- 1,492 U tumor necrosis factor-alpha per milliliter) and reduced nitric oxide synthesis as measured by plasma nitrite and nitrate (352 +/- 69 mumol/L). Polyclonal rabbit anti-mouse anti-tumor necrosis factor-alpha also reduced lipopolysaccharide-induced hepatic enzyme release (428 +/- 33 IU AST/L; 16.0 +/- 2.5 IU ornithine carbamoyltransferase per liter). NG-monomethyl-L-arginine, a competitive inhibitor of nitric oxide synthesis, also decreased plasma nitrite and nitrate (104 +/- 9 mumol/L) but increased the lipopolysaccharide-induced hepatic injury (797 +/- 66 IU AST/L; 33.1 +/- 2.1 IU ornithine carbamoyltransferase per liter).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Remote tissue injury primes hepatocytes for nitric oxide synthesis.

Following trauma and tissue injury, patients frequently suffer infections and septic complications. Tissue injury is associated with the induction of the hepatic acute-phase response, but how this phenotypic expression by hepatocytes influences their subsequent response to endotoxin (lipopolysaccharide, LPS) or inflammatory cytokines is unknown. We have shown that both rat and human hepatocytes maximally express the enzyme-inducible nitric oxide synthase (iNOS) in response to a combination of LPS and the cytokines tumor necrosis factor (TNF), interferon-gamma (IFN-gamma), and interleukin-1. Furthermore, we have shown that the in vivo induction of the acute-phase response following tissue injury (hind limb turpentine injection) is not associated with hepatocyte iNOS expression. In this study, we show that the phenotypic change associated with the acute-phase response following tissue injury primes the hepatocyte to subsequently express iNOS in vitro in response to LPS alone as well as TNF and IFN-gamma. This expression of iNOS can be seen as early as 3 hr following the initial injury and lasts up to 24 hr. Early postinjury changes result in maximal expression following stimulation with TNF or IFN-gamma. Later (24 hr post-injury) changes reveal LPS to be the most potent inducer with as little as 0.01 microgram/ml LPS being required for iNOS mRNA expression. The in vivo correlate of tissue injury (turpentine injection) followed by sepsis (intraperitoneal LPS injection) resulted in a three- to fourfold rise in plasma levels of the stable end-products of nitric oxide production, nitrite, and nitrate (NO2- + NO3-), over levels seen in cases of sepsis alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

A potential role for nitric oxide in myocardial stunning.

Nitric oxide (NO) production by the human heart has been demonstrated in patients undergoing cardiac surgery. Similar to what has been described in other species, a basal production of NO by the human heart is seen (126 +/- 42 pmol/min per gram). Following reperfusion, at the end of the procedure, the level of NO production increases significantly reaching concentrations of 1430 +/- 330 pmol/min per gram. Increased activity for the enzyme NO synthase (NOS) (8.0 +/- 1.2 pmol/mg prebypass vs 26.4 +/- 4.8 pmol/mg postbypass) coincides with changes in NO production and occurs at a time when myocardial stunning is clinically detectable. The significance of these findings is discussed and suggest a role for NO in the pathophysiology of myocardial stunning.

Amino Acid Oxidoreductases↗

PubMed1994

Nitric oxide-mediated antiplasmodial activity in human and murine hepatocytes induced by gamma interferon and the parasite itself: enhancement by exogenous tetrahydrobiopterin.

Expression of inducible nitric oxide (NO) synthase has been shown to inhibit the development of several pathogens, including fungi, bacteria, parasites, and viruses. However, there is still controversy as to whether this effector mechanism can inhibit the development of human pathogens. We now report that gamma interferon (IFN-gamma) induces the elimination of Plasmodium falciparum-infected primary human hepatocytes from cultures and that the antimalarial activity is dependent on NO. Infection with the parasite alone in the absence of added IFN-gamma caused a 10-fold increase in NO formation. Both spontaneous inhibition and IFN-gamma-induced inhibition of Plasmodium yoelii-infected murine hepatocytes were increased with the addition of the NO synthase cofactor tetrahydrobiopterin, or sepiapterin, which is converted to tetrahydrobiopterin. These results indicate that under in vitro conditions the parasite itself provides a signal that triggers induction of the NO pathway in human and murine hepatocytes and that NO formation in infected hepatocytes is limited by tetrahydrobiopterin availability.

Animals↗

PubMed1994

Hepatocyte inducible nitric oxide synthesis is influenced in vitro by cell density.

Hepatocyte plating density is known to affect cell function. Human and rat hepatocytes have been shown to express the inducible nitric oxide synthase (INOS) in response to cytokines plus lipopolysaccharide (LPS). The following studies were performed to determine the effects of hepatocyte plating density on the regulation of INOS. Rat hepatocytes were plated at densities from 10(4) to 20 x 10(4) hepatocytes/cm2 and stimulated with a combination of LPS, interferon-gamma, interleukin-1, and tumor necrosis factor. We found that NO2- plus NO3- released from stimulated hepatocytes declines with increasing hepatocyte density. Similar effects were seen for 3',5'-cyclic monophosphate release into supernatants and in the amount of nonheme iron-nitrosyl signals measured by electron paramagnetic resonance spectroscopy. Limitations of substrate (L-arginine) and 5,6,7,8-tetrahydrobiopterin were excluded as cause of the reduced nitric oxide generation at higher densities. Although mRNA levels for INOS were not influenced when measured at 24 h, there was a marked reduction in INOS enzyme activity and INOS protein detectable by Western blotting at higher cell density. Total protein synthesis decreased as hepatocyte density increased in both nonstimulated and stimulated hepatocytes at higher cell densities. These data suggest that reduced INOS translation may account for the density-dependent reduction in INOS activity in cultured hepatocytes. The importance of this phenomenon remains to be determined in vivo but has important implications for the in vitro study of INOS expression.

Amino Acid Oxidoreductases↗

PubMed1994

New insights into the regulation of inducible nitric oxide synthesis.

Recent studies have identified the induction of nitric oxide (NO) synthesis in many cell types as part of the host response to sepsis and inflammation. Induced NO can have a variety of effects which may be detrimental or beneficial during sepsis or inflammation, depending on amount, duration, and anatomic site of synthesis. As arginine is the only physiological nitrogen donor for NO synthesis, metabolism of this amino acid may play an important role in regulation of NO synthesis during sepsis. This review will discuss the roles NO plays in sepsis and the potential impact of arginine metabolism on NO synthesis.

Animals↗

PubMed1994

Nitric oxide and prostaglandins interact to prevent hepatic damage during murine endotoxemia.

Nitric oxide (NO) and prostaglandins (PG) both possess the ability to induce vasodilatation and prevent the aggregation of platelets. The synthesis of these substances is increased following in vivo lipopolysaccharide (LPS) infusion, but their function during sepsis is incompletely understood. We studied the role of NO and PG in a murine model of chronic hepatic inflammation (Corynebacterium parvum injection), which is known to progress to sudden hepatic necrosis after LPS injection. NO synthesis, which is induced in hepatocytes by C. parvum treatment and in nonparenchymal cells by LPS treatment, was inhibited using NG-monomethyl-L-arginine (L-NMMA). High-dose aspirin (ASA) was used to block PG synthesis. Treatment with L-NMMA or ASA alone, in the absence of LPS, resulted in no increase in hepatic injury. C. parvum-treated mice that received both L-NMMA and ASA without LPS developed marked hepatic damage as reflected by increased hepatocellular enzyme release (aspartate aminotransferase and L-ornithine carbamoyl-transferase). Marked hepatic damage was seen after LPS administration, and ASA pretreatment alone had no effect on the LPS-induced hepatic injury, whereas L-NMMA markedly increased the hepatic damage. The combination of L-NMMA and ASA after LPS resulted in the greatest hepatocellular enzyme release, characterized histologically by intravascular thrombosis with diffuse infarction and necrosis. Simultaneous treatment with either PGI2 or L-arginine partially prevented this injury. These data demonstrate that NO and PG function synergistically to maintain hepatocellular integrity; thus increased synthesis of these mediators protects the liver from the pathophysiological effects of LPS in this model.

Animals↗

PubMed1994

Tetrahydrobiopterin synthesis and inducible nitric oxide production in pulmonary artery smooth muscle.

We recently reported (Am. J. Respir. Cell Mol. Biol. 7: 471-476, 1992) that a mixture of lipopolysaccharide (LPS) and cytokines produced a time-dependent increase in mRNA and protein expression of inducible nitric oxide synthase (iNOS) in cultured rat pulmonary artery smooth muscle cells (RPASM). In the current study we extend observations on regulation of iNOS in RPASM by showing that de novo synthesis of tetrahydrobiopterin (BH4) is critical for LPS and cytokine-induced NO production. A mixture of LPS and the cytokines gamma-interferon, interleukin-1 beta, and tumor necrosis factor-alpha increased steady-state levels of mRNA of GTP-cyclohydrolase-I (GTP-CH), the rate-limiting enzyme in BH4 biosynthesis. Levels of mRNA to GTP-CH became detectable by 4 h, with further increases at 24 h by Northern blot analysis and reverse-transcriptase polymerase chain reaction. Total intracellular biopterin levels, undetectable under basal conditions, increased after 24 h exposure to LPS and cytokines (to 32.3 +/- 0.8 pmol/mg protein). LPS and cytokine-induced NO production, determined by nitrite concentrations in the medium, was decreased in a concentration-dependent manner by the GTP-CH inhibitor, 2,4-diamino-6-hydroxypyrimidine (DAHP) at 24 h. DAHP also inhibited completely the LPS- and cytokine-induced accumulation of intracellular biopterins. Sepiapterin, which supplies BH4 through a salvage pathway independent of GTP-CH, reversed the effect of DAHP on LPS and cytokine-induced NO production.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1994

Hemodynamic effects and metabolic fate of inhaled nitric oxide in hypoxic piglets.

We describe the hemodynamic effects and metabolic fate of inhaled NO gas in 12 anesthetized piglets. Pulmonary and systemic hemodynamic responses to incremental [NO] (5-80 ppm) were tested during ventilation with high- [0.30 inspired O2 fraction (FIO2)] and low-O2 (0.10 FIO2) mixtures. In six animals, inhalation of 40 ppm NO was maintained over 6 h to test effects of prolonged exposure (0.30 FIO2). In the other six animals, pulmonary hypertension was induced by hypoxic ventilation (0.10 FIO2) and responses to NO were tested. Inhaled low [NO] partially reversed pulmonary hypertension induced by alveolar hypoxia; mean pulmonary arterial pressure decreased from 31.4 +/- 2.3 mmHg during hypoxia to 18.2 +/- 1.2 mmHg during 5 ppm NO. Mean pulmonary arterial pressure at 0.10 FIO2 did not fall further at higher [NO] (10-40 ppm) and never reached control levels. Pulmonary vascular resistance increased with institution of hypoxic ventilation and fell with subsequent administration of NO, ultimately reaching control levels. Inhaled NO did not affect systemic vascular resistance. Plasma levels of NO2- + NO3- and methemoglobin (MetHb) levels increased with increasing [NO]. Over 6 h of NO administration during high-O2 ventilation, MetHb equilibrated at subtoxic levels while NO2- + NO3- increased. Nitrosylhemoglobin, analyzed by electron paramagnetic resonance spectrophotometry was not detected in blood at any time. At the relatively low concentrations (5-80 ppm) that are effective in relieving experimental pulmonary hypertension induced by alveolar hypoxia, inhaled NO gas causes accumulation of NO2- + NO3- in plasma and a small increase in MetHb but no detectable nitrosylhemoglobin.

Administration, Inhalation↗

PubMed1993

Induction of nitric oxide synthesis and its reactions in cultured human and rat hepatocytes stimulated with cytokines plus LPS.

We have examined the time course of appearance of mRNA for nitric oxide synthase (NOS), intracellular nonheme iron-nitrosyl complexes (NHFeNO, detected by EPR spectroscopy), and rates of medium appearance of NO2- + NO3- in cultured rat and human hepatocytes stimulated with a combination of cytokines (TNF-alpha, IFN-gamma, IL-1 beta) and LPS. In both cells types, NOS mRNA precedes NHFeNO formation which in turn precedes maximum rates of NO2- + NO3- (NOx) formation. This profile occurs earlier in human hepatocytes than rat hepatocytes and the appearance of NOS mRNA is also more transient. These results indicate that (1) NOS is stable intracellularly (peak NOx production occurs substantially after peak mRNA levels), (2) intracellular iron is an early target (preceding maximum NOx production) for NO in both human and rat hepatocytes, and (3) decline in NHFeNO in the face of maximum NOx production indicates the presence of a "repair" or "removal" mechanism for these intracellular iron-nitrosyl complexes.

Amino Acid Oxidoreductases↗

PubMed1993

Molecular cloning and expression of inducible nitric oxide synthase from human hepatocytes.

Nitric oxide is a short-lived biologic mediator for diverse cell types. Synthesis of an inducible nitric oxide synthase (NOS) in murine macrophages is stimulated by lipopolysaccharide (LPS) and interferon gamma. In human hepatocytes, NOS activity is induced by treatment with a combination of tumor necrosis factor, interleukin 1, interferon gamma, and LPS. We now report the molecular cloning and expression of an inducible human hepatocyte NOS (hep-NOS) cDNA. hep-NOS has 80% amino acid sequence homology to macrophage NOS (mac-NOS). Like other NOS isoforms, recognition sites for FMN, FAD, and NADPH are present, as well as a consensus calmodulin binding site. NOS activity in human 293 kidney cells transfected with hep-NOS cDNA is diminished by Ca2+ chelation and a calmodulin antagonist, reflecting a Ca2+ dependence not evident for mac-NOS. Northern blot analysis with hep-NOS cDNA reveals a 4.5-kb mRNA in both human hepatocytes and aortic smooth muscle cells following stimulation with LPS and cytokines. Human genomic Southern blots probed with human hep-NOS and human endothelial NOS cDNA clones display different genomic restriction enzyme fragments, suggesting distinct gene products for these NOS isoforms. hep-NOS appears to be an inducible form of NOS that is distinct from mac-NOS as well as brain and endothelial NOS isozymes.

Amino Acid Oxidoreductases↗

PubMed1993

Cytokines, endotoxin, and glucocorticoids regulate the expression of inducible nitric oxide synthase in hepatocytes.

Nitric oxide (NO.) is a short-lived mediator which can be induced in a variety of cell types and produces many physiologic and metabolic changes in target cells. The inducible or high-output NO. synthase (NOS) pathway was first characterized in macrophages activated by lipopolysaccharide (LPS) and interferon gamma (IFN-gamma). Hepatocytes also express an inducible NOS following exposure to the combination of endotoxin (LPS) and tumor necrosis factor (TNF), interleukin 1 (IL-1), and IFN-gamma. In this study, to identify which of these cytokines, if any, was acting to induce the gene expression for hepatocyte NOS, we measured the levels of rat hepatocyte NOS mRNA by Northern blot analysis after stimulation by various combinations of endotoxin and cytokines in vitro. We found the mRNA for hepatocyte NOS to be a single band at approximately 4.5 kilobases which was maximally up-regulated (approximately 70-fold) by the combination of TNF, IL-1, IFN-gamma, and LPS. Abundance of NOS mRNA peaked 6-8 hr after stimulation and then declined by 25% at 24 hr. Unstimulated hepatocytes in vitro showed only a trace mRNA band after prolonged autoradiographic exposure. As single agents, TNF and IL-1 were the most effective inducers of hepatocyte NOS mRNA. Combinations of two or three stimuli revealed strong synergy between TNF, IL-1, and IFN-gamma. The increased mRNA levels correlated with elevated nitrogen oxide release and cGMP levels in the culture supernatants. Dexamethasone and cycloheximide inhibited induction of mRNA for hepatocyte NOS in a dose-dependent fashion. The addition of NG-monomethyl-L-arginine had no effect on mRNA levels but effectively blocked NO. formation. The inducible hepatocyte NOS mRNA was also detected in rat hepatocytes following chronic hepatic inflammation triggered by Corynebacterium parvum injection in vivo. These data demonstrate that the inducible NOS is functional in rat hepatocytes both in vitro and in vivo and that this pathway is under complex control. Endotoxin and inflammatory cytokines act synergistically to up-regulate gene expression for hepatocyte NOS, whereas glucocorticoids down-regulate the mRNA.

Amino Acid Oxidoreductases↗

PubMed1993

Induction of hepatocyte lipopolysaccharide binding protein in models of sepsis and the acute-phase response.

Lipopolysaccharide binding protein (LBP) is a serum glycoprotein that complexes with lipopolysaccharide (LPS) to facilitate macrophage response to endotoxin. To determine the conditions that stimulate LBP production in vivo, we measured the induction of LBP in models of inflammation produced by LPS, Corynebacterium parvum, and turpentine injection. Plasma aspartate aminotransferase and alanine aminotransferase concentrations and hepatocyte fibrinogen synthesis were elevated in all models. Northern blot analysis revealed 17-, 14-, and 20-fold upregulation of hepatocyte LBP mRNA following treatment with LPS, C parvum, and turpentine, respectively. Peritoneal macrophage interleukin 6 and tumor necrosis factor production following endotoxin stimulation was augmented by cultured hepatocyte supernatants, suggesting increased LBP synthesis in these groups. The results show that LBP mRNA is induced during hepatic inflammation and suggest that LBP is an acute-phase protein important in regulating the in vivo response to endotoxin.

Acute-Phase Proteins↗

PubMed1993

Should surgeons clone genes? The strategy behind the cloning of the human inducible nitric oxide synthase gene.

Nitric oxide (NO) is a recently recognized biological mediator that has triggered an explosion of scientific research over the last 5 years, resulting in NO being named "Molecule of the Year" by Science in 1992. Much of the excitement is due to the physiological and pathophysiological functions exerted by NO as a vasodilator, neurotransmitter, and antimicrobial effector molecule. The purpose of this review is to describe the cloning of the inducible NO synthase gene from human hepatocytes, with particular emphasis on the importance to surgeons of cloning genes and on the utility of applying modern molecular biology to the study of diseases relevant to surgical practice. Overall cloning techniques and the specific strategy used to clone the human inducible NO synthase gene are reviewed. In addition, applications of gene cloning to clinical surgery are discussed. Isolating the inducible human NO synthase gene has provided important information regarding the regulation of induced NO synthesis in human cells and has provided a critical tool for further studies to define the role of NO in normal and disease processes.

Amino Acid Oxidoreductases↗