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W Hagmann

Publications and source records attributed to W Hagmann.

At least 37 records · Page 2Linked to original sources
PubMed1991

PMN elastases: a comparison of the specificity of human isozymes and the enzyme from other species toward substrates and inhibitors.

The human elastases isolated from polymorphonuclear neutrophils (PMN) and purulent sputum displayed identical kinetic constants toward substrates and inhibitors. The elastases from the two sources yield identical N-terminal sequences and were recognized by antiserum prepared against human sputum elastase (HSE) isozyme-4 (I-4). The data support the proposal put forth by Twumasi and Liener (1977, J. Biol. Chem. 252, 1917-1926) that the human elastase from sputum is of PMN origin. PMN elastases from other species displayed kinetic constants toward both substrates and inhibitors significantly different from the human enzyme. Therefore, extrapolation of inhibitor profiles from these elastases to the human source should be avoided. Four groups of isozymes were resolved from HSE by FPLC. Only the most basic isozyme (I-4) was obtained as a single species. The isozymes displayed identical macroscopic kinetic constants toward several substrates and two classes of inhibitors. The similar partition ratios observed with a cephalosporin-derived inhibitor suggest that the microscopic rate constants are also identical. The data support the proposal suggested by Baugh and Travis (1976, Biochemistry 15, 836-841) that HLE isozymes differ only in carbohydrate content. Whatever the source of human PMN elastase heterogeneity, it does not result in heterogeneous catalytic properties. In addition, a new protein was identified in elastase preparations derived from human sputum. This protein displayed homology to serine proteases and properties suggesting that it is identical to azurocidin.

Amino Acid Sequence↗
PubMed1991

The sensitized liver represents a rich source of endogenous leukotrienes.

The ability of livers to produce endogenous leukotrienes after immunological stimulation was tested with organs from rats and guinea pigs. Passive sensitization of rats in vivo with monoclonal murine antidinitrophenol-IgE before antigen challenge in the isolated perfused liver system elicited a rapid hepatic production and biliary excretion of leukotrienes as judged by radioimmunoassay after separation of individual leukotrienes by high-performance liquid chromatography. Within 10 min after antigen infusion, mainly leukotriene C4, but also leukotriene D4 and N-acetyl-leukotriene E4, appeared in the bile. The biliary excretion rate of antigen-induced cysteinyl leukotrienes rose from less than 2 pmol.min-1.(kg body mass)-1 before challenge to about 30 pmol.min-1.(kg body mass)-1 for 20 min before it declined toward prechallenge level. Quantitatively similar hepatic production of cysteinyl leukotrienes was elicited in isolated perfused guinea pig livers challenged with ovalbumin after active sensitization of the animals with ovalbumin plus Al(OH)3. To exclude extrahepatic contributions to the observed leukotriene production, both passive sensitization with anti-dinitrophenol-IgE and subsequent antigen challenge were performed on isolated rat livers perfused with blood-free medium. Such exclusively hepatic sensitization and challenge also resulted in massive production of leukotrienes. The biliary excretion rate of cysteinyl leukotrienes amounted to approximately 20 pmol.min-1.(kg body mass)-1 during the 10 to 20 min period after antigen challenge as compared with less than 1 pmol.min-1.(kg body mass)-1 before challenge.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaphylaxis↗
PubMed1990

Hepatic uptake and metabolic disposition of leukotriene B4 in rats.

1. In isolated perfused rat liver and in vivo, up to 25% of [3H]leukotriene B4 was eliminated from the circulation via hepatic uptake and biliary excretion within 1 h. Total body recovery of 3H amounted to about 60% of infused [3H]leukotriene B4. 2. Hepatobiliary excretion of leukotriene B4 and its metabolites exceeded renal elimination by about 4-fold and depended, in contrast with excretion of cysteinyl leukotriene E4, upon continuous taurocholate supply. 3. Analyses of bile, liver and recirculated perfusate using h.p.l.c. indicated that the liver metabolized leukotriene B4 extensively to omega-carboxyleukotriene B4 and its beta-oxidized derivatives, and no unmetabolized leukotriene B4 appeared in bile. These results substantiate the important contribution of the hepatobiliary system with respect to the metabolic fate of leukotriene B4.

Animals↗
PubMed1990

Inhibition of leukotriene omega-oxidation by isonicotinic acid hydrazide (isoniazid).

Metabolism of leukotrienes via omega-oxidation represents a major degradative and inactivating pathway of these biologically active icosanoids. Isonicotinic acid hydrazide (isoniazid) inhibited this process in rats in vivo, in the isolated perfused rat liver, and in hepatic microsomes. The in vivo catabolism of leukotriene E4 via N-acetyl-leukotriene E4 to its omega-oxidized metabolites was inhibited by 50% or 71% using single intravenous isoniazid doses of 0.6 mmol or 1.0 mmol/kg body mass, respectively. Isoniazid interfered with leukotriene catabolism at the initial omega-oxidation step, resulting in an accumulation of N-acetyl-leukotriene E4. Analogous although weaker inhibition of leukotriene omega-oxidation in vivo was observed by pretreatment with isonicotinic acid 2-isopropylhydrazide and monoacetyl hydrazine. In the isolated perfused liver, isoniazid at concentrations varying over 0.2-10 mM decreased the omega-oxidation of cysteinyl leukotrienes dose-dependently by up to 94%. omega-Oxidation of both leukotriene E4 and leukotriene B4 by rat liver microsomes was inhibited by isoniazid, isonicotinic acid 2-isopropylhydrazide, and monoacetyl hydrazine with half-maximal concentrations in the range of 5-15 mM. Our measurements indicate that the impairment of leukotriene omega-oxidation by isoniazid involves both cytochrome-P450-dependent enzyme systems responsible for omega-oxidation of leukotriene E4 and leukotriene B4. In effect, under isoniazid treatment one can expect a prolongation of the proinflammatory actions of endogenously produced leukotrienes.

Animals↗
PubMed1990

A comparison of alpha 1-proteinase inhibitor methoxysuccinyl-Ala-Ala-Pro-Val-chloromethylketone and specific beta-lactam inhibitors in an acute model of human polymorphonuclear leukocyte elastase-induced lung hemorrhage in the hamster.

A pharmacokinetic model is described for testing of polymorphonuclear leukocyte (PMN) elastase inhibitors administered by intratracheal or aerosol dosing of hamsters. Acute lung injury, measured as hemorrhage occurring within hours after intratracheal instillation of human PMN elastase, correlated directly with the amount of active enzyme instilled. Hemorrhage began within minutes of elastase instillation, was maximal within 1 h, and remained constant for up to 5 h subsequently. Therefore, inhibition of hemorrhage was used as an assay of the effectiveness of various PMN elastase inhibitors given by the intratracheal route. Lung hemorrhage could also be induced by intratracheal instillation of other elastolytic enzymes, such as thermolysin, and inhibition of hemorrhage was seen only with inhibitors active against the type of elastase used. Methoxysuccinyl-alanyl-alanyl-prolyl-valine-chloromethylketone (MeOSuc-AAPV-CMK), as well as alpha 1-proteinase inhibitor (alpha 1PI) but not tosyl-lysine-chloromethylketone (tosyl-lysine-CMK), inhibited the hemorrhage caused by human PMN elastase, but the specific inhibitors of this enzyme had no effect on thermolysin-induced lung hemorrhage. The duration of activity of these compounds as elastase inhibitors in this model correlated directly with the extent of their persistence in lung lavage fluid as determined by HPLC analysis of compound recovered by bronchoalveolar lavage. (ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Chloromethyl Ketones↗
PubMed1989

Uptake, production and metabolism of cysteinyl leukotrienes in the isolated perfused rat liver. Inhibition of leukotriene uptake by cyclosporine.

1. The isolated perfused rat liver efficiently takes up cysteinyl leukotrienes (LTs) C4, D4, E4 and N-acetyl-LTE4 from circulation. More than 70% of these cysteinyl LTs are excreted from liver into bile within 1 h of onset of a 5 min infusion, while about 5% remain in the liver. About 20% of infused N-acetyl-LTE4 escapes hepatic first-pass extraction under our conditions. 2. Metabolites of LTC4 appearing in bile within 20 min of the onset of infusion include mainly LTD4 and N-acetyl-LTE4, but also omega-hydroxy-N-acetyl-LTE4 and omega-carboxy-N-acetyl-LTE4. Metabolites generated from omega-carboxy-N-acetyl-LTE4 by beta-oxidation from the omega-end represent the major biliary LTs secreted at later times. 3. Stimulation of the isolated perfused liver by the combined infusion of the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) and the Ca2+ ionophore A23187 results in a transient increase of endogenous cysteinyl LT production, which is independent of extrahepatic cells. 4. The immunosuppressive drug cyclosporine causes a dose-dependent inhibition of hepatobiliary cysteinyl LT excretion, probably by interference with the sinusoidal uptake system for cysteinyl LTs.

Animals↗
PubMed1988

Leukotriene C4 metabolism during its action on glucose and lactate balance and flow in perfused rat liver.

Rat livers were perfused in a non-recirculating mode at constant pressure via the portal vein with media containing 5 mM glucose, 2 mM lactate, and 0.2 mM pyruvate. [3H]LTC4 was infused for a period of 5 min to a final concentration of 20 nM; it increased glucose and lactate output and reduced perfusion flow. 1) Leukotriene radioactivity was recovered 10 min after the onset of [3H]LTC4 infusion to about 40% in the effluent, to 20% in the bile, and to 40% in the liver. 2) Radioactivity in the effluent increased to a maximum 4-5 min after the onset and decreased again to essentially zero 3 min after completion of [3H]LTC4 infusion. [3H]LTC4 and [3H]LTD4 were the major labeled components in the effluent accounting for 45% and 38%, respectively, of the effluent radioactivity. 3) [3H]LTC4 and [3H]LTD4 were also the major components in bile; they accounted for 50% and 30%, respectively, of the radioactivity excreted, while more polar [3H]leukotriene metabolites accounted for the remainder. 4) In the liver, [3H]LTC4 and [3H]LTD4 were the major and [3H]LTE4, N-acetyl-[3H]LTE4 as well as omega-hydroxy-N-acetyl-[3H]LTE4 and omega-carboxy-N-acetyl-[3H]LTE4 were minor components detected 5 min after completion of [3H]LTC4 infusion. It is concluded from the present findings that during a 5 min infusion period about one third each of the infused LTC4 remained unchanged, was converted to LTD4, and was further degraded to LTE4 and polar metabolites including omega-oxidation products of N-acetyl-LTE4.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Leukotriene C4 metabolism by hepatoma cells and liver.

The metabolism of the glutathionyl leukotriene LTC4 in the mercapturic acid pathway was studied in suspensions of AS-30D hepatoma cells and hepatocytes, as well as in vivo in the bile duct-cannulated rat and in primates. 1. Isolated hepatocytes actively took up cysteinyl leukotrienes and metabolized LTC4 not only to LTD4 and LTE4 but also to N-acetyl-LTE4 and to metabolites more polar than LTC4. 2. AS-30D hepatoma cells are deficient in the transport system for the uptake of cysteinyl leukotrienes. Peptide cleavage of LTC4 to LTD4 and LTE4 was catalyzed by ectoenzymes of these cells. Inactivation of gamma-glutamyltransferase by acivicin and inhibition of LTD4 dipeptidase by penicillamine largely prevented further catabolism of LTC4 and LTD4, respectively. 3. [3H]LTC4 injected i.v. into rats was rapidly eliminated from the circulating blood, taken up by the liver, and excreted into bile where 77% of the administered radioactivity was recovered within 1 hr. The biliary LTC4 metabolites included LTD4, N-acetyl-LTE4, and metabolites more polar than LTC4. 4. Inhibition of [3H]LTC4 metabolism in vivo by i.v. penicillamine shifted the pattern of biliary cysteinyl leukotrienes; an extended half-life of [3H]LTD4 was associated with a retarded formation of N-acetyl-LTE4 and of polar metabolites. 5. Endogenous cysteinyl leukotrienes elicited by trauma were measured after HPLC separation by radioimmunologic analysis in plasma and bile of rats. The biliary concentration of these leukotrienes was up to 100 times as great as in plasma. N-Acetyl-LTE4 was the predominant endogenous metabolite in rat bile. 6. In the monkey Macaca fascicularis, cysteinyl leukotrienes were predominantly eliminated from blood via the liver into bile; renal excretion amounted to about 50% of the hepatobiliary elimination. Absorption of cysteinyl leukotrienes from the intestine resulted in enterohepatic circulation of these mediators. 7. Metabolites of [3H]LTC4 injected i.v. in the monkey were analyzed in bile and urine. In addition to polar metabolites and a small percentage of [3H]LTD4, [3H]LTE4 was a predominant metabolite particularly in bile. LTE4 was also the major endogenous cysteinyl leukotriene detected by radioimmunologic analysis in monkey bile. 8. LTE4 was the predominant endogenous cysteinyl leukotriene measured in human bile in patients suffering from acute pancreatitis. The detected amounts of LTE4 may be sufficient to induce known phenomena associated with acute pancreatitis including the shock-like reaction.

Animals↗
PubMed1987

Enterohepatic circulation of N-acetyl-leukotriene E4.

N-Acetyl-leukotriene E4, the end product of leukotriene C4 metabolism in the mercapturic acid pathway, was rapidly eliminated from the blood circulation into the bile of rats. Part of the N-acetyl-leukotriene E4 secreted from bile into the intestine underwent enterohepatic circulation. Leukotriene absorption occurred from the small intestine and from the colon. Biliary and urinary excretion within 5.5 h amounted to 15 and 2%, respectively, of the intraduodenally administered N-acetyl- 3H leukotriene E4 in animals anesthetized with ketamine. HPLC analyses indicated that 35% of the biliary radioactivity corresponded to unchanged N-acetyl-3H leukotriene E4, while 65% in bile and 100% in urine were polar metabolites. Enterohepatic circulation extends the biological half-life of N-acetyl-leukotriene E4.

Animals↗
PubMed1986

Identification of the major endogenous leukotriene metabolite in the bile of rats as N-acetyl leukotriene E4.

Mercapturic acid formation, an established pathway in the detoxication of xenobiotics, is demonstrated for cysteinyl leukotrienes generated in rats in vivo after endotoxin treatment. The mercapturate N-acetyl-leukotriene E4 (N-acetyl-LTE4) represented a major metabolite eliminated into bile after injection of [3H]LTC4 as shown by cochromatography with synthetic N-acetyl-LTE4 in four different HPLC solvent systems. The identity of endogenous N-acetyl-LTE4 elicited by endotoxin in vivo was additionally verified by enzymatic deacetylation followed by chemical N-acetylation. The deacetylation was catalyzed by penicillin amidase. Endogenous cysteinyl leukotrienes were quantified by radioimmunoassay after HPLC separation. A N-acetyl-LTE4 concentration of 80 nmol/l was determined in bile collected between 30 and 60 min after endotoxin injection. Under this condition, other cysteinyl leukotrienes detected in bile by radioimmunoassay amounted to less than 5% of N-acetyl-LTE4. The mercapturic acid pathway, leading from the glutathione conjugate LTC4 to N-acetyl-LTE4, thus plays an important role in the deactivation and elimination of these potent endogenous mediators.

Animals↗
PubMed1985

Leukotrienes as mediators in tissue trauma.

A significant increase in the production of cysteinyl leukotrienes was observed after mechanical or thermal trauma in the anesthesized rat. The amount of biliary N-acetyl-leukotriene E4, which represents a suitable indicator for blood plasma leukotrienes, was used as a measure of leukotriene generation. Cysteinyl leukotrienes were rapidly eliminated from blood plasma into bile where N-acetyl-leukotriene E4 was the major metabolite. Leukotrienes were at a much lower concentration in blood plasma than in bile and differed in the pattern of metabolites. The detected amounts of leukotrienes were sufficient to induce known phenomena associated with trauma, such as tissue edema and circulatory and respiratory dysfunction. Increased leukotriene generation appears to play an important role in the pathophysiology of tissue trauma.

Animals↗
PubMed1985

Production of peptide leukotrienes in endotoxin shock.

Arachidonate metabolites are potent mediators generated in endotoxin shock. Following endotoxin administration (15 mg/kg) into unanesthetized rats, we found a rapid biliary secretion of peptide leukotrienes. Analysis of bile for peptide leukotrienes included organic solvent extractions, reversed phase-HPLC, radioimmunoassay (RIA), and spectrophotometry. The major immunoreactive endogenous leukotriene (LT) from bile was eluted between LTC4 and LTD4 in three chromatographic systems. It corresponded thereby to a biliary metabolite of injected LTC4 and LTD4 which in turn showed the ultraviolet spectrum of a peptide leukotriene. This demonstration of endotoxin-induced generation of peptide LTs in vivo was possible by sequential HPLC and RIA analyses in bile into which peptide LTs are eliminated from blood.

Animals↗
PubMed1984

Role of peptide leukotrienes and their hepatobiliary elimination in endotoxin action.

The lethal action of endotoxin was studied in mice sensitized against the lipopolysaccharide by D-galactosamine. Protection was obtained by FPL 55712, a selective antagonist of sulfidopeptide leukotrienes, by diethylcarbamazine, an inhibitor of leukotriene biosynthesis, by BW 755C, a dual lipoxygenase and cyclooxygenase inhibitor, and by dexamethasone, which inhibits arachidonate release. Indomethacin incompletely antagonized endotoxin lethality; indoprofen did not protect at all. Leukotriene generation induced by endotoxin in vivo could be demonstrated in rats by employing a radioimmunoassay on bile extracts since intravascular sulfidopeptide leukotrienes were rapidly eliminated into bile. Additionally, however, endotoxin affected the hepatobiliary elimination of sulfidopeptide leukotrienes. From intravenously injected tracer [3H]leukotriene D4, 67% appeared only partially metabolized in bile within 30 min in control rats. Endotoxin and lipid A reduced the biliary [3H]leukotriene D4 secretion by up to 80% while enhancing the hepatic [3H]leukotriene D4 content up to twofold. This inhibition of hepatobiliary elimination was stronger than endotoxin-induced reductions of bile flow or of biliary [14C]taurocholate secretion. Endotoxin, as an activator of the arachidonate cascade, thus potentiates its action in vivo by interfering with the rapid hepatobiliary clearance of sulfidopeptide leukotrienes in addition to stimulating leukotriene and prostanoid formation.

4,5-Dihydro-1-(3-(trifluoromethyl)phenyl)-1H-pyraz↗