Succinyl trialanine p-nitroanilide-hydrolytic enzymes in human serum. An improved method for clinical diagnosis

ONO-5046 is a potent inhibitor of neutrophil elastase in human pleural effusion after lobectomy

The imbalance of neutrophil elastase and alpha1-antitrypsin in pleural effusion after lobectomy and the effects of the neutrophil elastase inhibitors, sodium N-[2-[4-(2,2-Dimethylpropionyloxy)phenyl-sulfonylamino]benzo yl]aminoacetic acid (ONO-5046) and purified alpha1-antitrypsin, on neutrophil elastase activity were determined. The amount of neutrophil elastase complexed to alpha1-antitrypsin, measured by an enzyme-linked immunosorbent assay, was 170 times higher in pleural effusion than in blood 3 h after lobectomy. The alpha1-antitrypsin levels measured by laser nephelometry did not increase in either blood or pleural effusion. Although neutrophil elastase activity, measured by the hydrolysis of succinyl-(Ala)3-p-nitroanilide, was not detected in blood, it was increased in pleural effusion 3 h and 24 h after lobectomy. ONO-5046, but not alpha1-antitrypsin, reduced the neutrophil elastase activity in pleural effusion. There is an imbalance of neutrophil elastase and alpha1-antitrypsin in pleural effusion after lobectomy. ONO-5046 is a potent inhibitor of neutrophil elastase activity in human pleural effusion.

Inhalation toxicity of diborane in rats assessed by bronchoalveolar lavage examination

Changes in bronchoalveolar lavage fluid (BALF) and blood were examined to assess the toxic effects of diborane (B2H6, CAS: 19287-45-7) on the lung. Male Wistar rats were exposed to diborane at 20 ppm (intended concentration) for 4 h (phase I study) to evaluate time-course changes up to 14 days, and at 10 or 1 ppm (intended concentrations) to assess the dose-effect relationship after 3 days (phase II study). BALF parameters [leukocyte counts, alpha 1-antitrypsin (alpha 1-AT), superoxide dismutase (SOD), total protein, phospholipids etc.] were examined and biochemical and histopathological studies were also carried out. In the phase I study, neutrophils (%) in BALF increased on the day of exposure and then decreased gradually for 3 days. Rapid and marked increases in alpha 1-AT and SOD activity in BALF were detected on the day of exposure, and phospholipids had sharply increased on day 3. After 14 days, these parameters in the exposed rats had returned to their background level and alpha 1-AT decreased significantly. In the phase II study, total protein, alpha 1-AT activity and phospholipids in BALF showed dose-dependent increases, and serum alpha 1-AT activity increased significantly. Alveolar capillary and alveolar cell damage were confirmed in rats exposed to 20 ppm, 10 ppm or 1 ppm diborane for 4 h by evaluating the parameters examined. The protection system appeared to start operating immediately after exposure, and the recovery mechanism seemed to start operating 1 day after exposure and cease by day 14. The no-observed-effect level could not be observed.

Neutral metalloendopeptidase associated with the smooth muscle cells of pregnant rat uterus

The pregnant rat uterus contains a membrane-bound metalloendopeptidase that is biochemically and immunologically similar to kidney enkephalinase (E.C.3.4.24.11). The uterus enzyme readily cleaved specific neutral endopeptidase substrates and oxytocin as well as the synthetic elastase substrate, Suc(Ala)3-pNA, yet did not digest native elastin. Using specific inhibitors, the uterus endopeptidase was identified as a metallopeptidase and not a serine protease, having an absolute requirement for zinc and perhaps calcium for maximal activity. The uterus endopeptidase cross-reacted with polyclonal antiserum to kidney microvillar endopeptidase and a monoclonal antibody to common acute lymphocytic leukemia antigen. Immunohistochemical localization of the enzyme in a 17 day pregnant uterus indicated that the enzyme was localized on the smooth muscle bundles of the myometrium and the endometrial epithelium. Total enzyme activity was 25 times higher in the late-term pregnant uterus (17th day of pregnancy) than in the nonpregnant uterus. Enzyme levels dropped rapidly prior to parturition and within 4 days after delivery the enzyme activity had returned to control levels. Inhibition of NEP in uterine strips with phosphoramidon resulted in a marked potentiation of oxytocin-induced contractions. Our results suggest that the uterine endopeptidase may have an important role in regulating uterine smooth muscle cell contraction during the later stages of pregnancy through its action on oxytocin and perhaps other biologically active peptides.

Serum succinyltrialanine p-nitroanilide-hydrolytic activity in workers occupationally exposed to lead

The relationship between blood lead concentration and serum succinyltrialanine p-nitroanilide-hydrolytic (STN) activity was investigated in 74 workers occupationally exposed to lead and in 28 non-exposed workers. Exposure to lead was observed during transfer-printing processes in which paints or paint powders containing 20-50% lead were used. The mean lead concentration was 0.49 mg/m3 (0.12-1.43 mg/m3) in the working environment and 1.42 mg/m3 (0.21-4.34 mg/m3) in workers involved in printing processes. Serum STN activity became lower with increasing concentrations of blood lead (PbB) in non-exposed workers (controls). In lead-exposed workers, the activity decreased with increasing concentrations of PbB of 2.0 mumol/l and more, but increased when less than 1.9 mumol/l. Among lead-exposed workers with high PbB concentrations and/or with hepatic dysfunction, the STN/PbB ratio was distributed above the regression line obtained from the controls. The present investigation suggests that serum STN activity decreases in those highly exposed to lead. Enzymes such as elastase, which hydrolyzes succinyltrialanine p-nitroanilide and additionally is not inhibited by lead, may possibly be induced among lead workers when liver function is impaired.

Characterization of sheep alpha-1-proteinase inhibitor. Important differences from the human protein

The plasma proteinase inhibitor corresponding to alpha-1-proteinase inhibitor (alpha 1Pl) in humans was isolated from sheep plasma. Ovine alpha 1Pl is of higher molecular weight (62,000 daltons) than is human alpha 1Pl, is resistant to chemical oxidation by N-chlorosuccinimide, and has poor elastase-inactivating power compared with the corresponding inhibitor in humans. However, ovine alpha 1Pl is a potent trypsin inhibitor. Despite the differences indicated above, a partial homology (22 to 35%) exists between human and sheep alpha 1Pl, at least as analyzed through the first 20 residues of the sheep inhibitor. The weak elastase-inhibitory capacity of sheep alpha 1Pl is paralleled by the low content of elastase in the sheep neutrophil granule. These important differences between sheep and human neutrophils and plasma proteinase inhibitors should be borne in mind in designing experiments related to proteolytically mediated lung injury in the former species.

Effect of food intake on blood lead concentration in workers occupationally exposed to lead

Results from a cross-sectional study showed the concentration of lead in the blood of male workers, aged 20-55 years, occupationally exposed to lead in a steel factory, to be negatively correlated with the daily nutritional content of dietary fiber, iron and vitamin B1 (thiamine) intake. Furthermore, in experiments with rats injected subcutaneously with lead acetate, lead levels in blood and femur of animals on a vitamin-rich laboratory chow were lower than those fed a general laboratory chow. Moreover, in the group fed the vitamin-rich chow, lead excretion in feces increased, while excretion in urine did not. These results suggest that lead excretion from the body may be increased by a high intake of nutrients such as thiamine, iron and fiber, that lead excretion in feces via bile may be enhanced by a large intake of vitamins such as thiamine and that accordingly the lead concentration in the blood of the workers is reduced.

Partial purification and characterization of a rat kidney neutral endopeptidase that hydrolyzes succinyl trialanine-4-nitroanilide

The activity for the hydrolysis of succinyl trialanine-4-nitroanilide was higher in kidney homogenates of female rats and mice than in those of male rats and mice. An enzyme hydrolyzing the above substrate was extracted from female rat kidney homogenate and partially purified by means of gel filtration on Sepharose 4B, anion-exchange chromatography on DEAE-Sepharose CL-6B and affinity chromatography on carbobenzoxy-L-Ala-L-Ala-D-Ala-polylysine-agarose. The purified enzyme cleaved the bond between succinyl dialanine and alanine-4-nitroanilide of the substrate and showed a Km value of 3.3 mM at the optimal pH of 7.5. The activity was increased by Ca2+ and Mg2+, but inhibited by EDTA. With oxidized insulin B chain as a substrate, the enzyme cleaved the carbonyl bonds of Ala-14, Tyr-16 and Gly-23 efficiently, and those of His-5 and His-10 less efficiently.

Differentiation of endopeptidases and aminopeptidases by high-performance liquid chromatography of reaction products from chromogenic peptide p-nitroanilines as substrates

A method for differentiating endopeptidases and aminopeptidases on the basis of substrate specificity is presented. Various synthetic chromogenic substrates, succinyl-(Ala)3-p-nitroaniline, succinyl-(Ala)2-p-nitroaniline, (Ala)3-p-nitroaniline, and (Ala)2-p-nitroaniline, were incubated with various peptidases and the incubation mixtures were directly analyzed by high-performance liquid chromatography to determine the splitting patterns of these substrates by the enzymes. The substrates and hydrolyzed products containing the chromophore were separated on a reverse-phase column under isocratic conditions, and the chromophore was specifically detected in the effluent fractions by absorbance measurement at 314 nm. Endopeptidases, leucine aminopeptidase, and dipeptidyl aminopeptidase showed different patterns of cleavage of the substrates. This simple and rapid high-performance liquid chromatographic procedure is suitable for identifying the above activities in different fractions obtained during separation and purification studies. The same approach was applied to the simultaneous determination of three types of endopeptidase activities in rat tissues based on the ability of the enzymes to hydrolyze different sites in succinyl-(Ala)3-p-nitroaniline.

Demonstration of collagenase and elastase activities in the blister fluids from bullous skin diseases. Comparison between dermatitis herpetiformis and bullous pemphigoid

We have investigated potential mechanisms for blister formation by assaying proteolytic enzymes in the blister fluids of patients with various bullous diseases. Blister fluids were obtained from patients with dermatitis herpetiformis (DH), bullous pemphigoid (BP), chronic bullous disease of childhood (CBDC), and pemphigus vulgaris (PV). The cells were recovered by centrifugation, and the supernatants as well as the cell pellets were assayed first for collagenase activity using [3H]proline-labeled type I collagen as substrate. Collagenase activity could be detected in most cases with DH, BP, and CBDC, while no activity was found in 2 cases of PV or in 5 control blister fluids obtained from suction blisters induced in healthy control subjects. Elastase activity was assayed in the same blister fluids by using a synthetic substrate succinyl-(L-alanyl)3-paranitroanilide or soluble [14C]valine-labeled tropoelastin. High levels of elastase activity were present in all DH patients, while lower, but clearly detectable, levels were found in BP, CBDC, and PV. The enzyme activity in BP was inhibited by Na2EDTA, but not by phenylmethylsulfonyl fluoride (PMSF), and Ca2+ stimulated the activity, suggesting that the enzyme in BP was a metalloproteinase. In cell-free supernatants of the DH blister fluids, the elastase activity was markedly decreased by PMSF, indicating that most of the enzyme activity was due to a serine protease. The cells recovered from DH blister fluids also contained high levels of elastase activity which could be inhibited by PMSF but not by Na2EDTA. Thus, in DH, the elastase activity is probably derived from polymorphonuclear leukocytes abundantly present in the lesions. The results indicate that active proteases are present in the blister fluids of skin diseases, and they may play a mechanistic role in the blister formation by degrading connective tissue components of the dermis and the dermal-epidermal junction.