Search PubMed⌕ Search

Biomedical subjects

W Hornebeck

Publications and source records attributed to W Hornebeck.

140 records · Page 8Linked to original sources
PubMed1977

Elastase-like enzymes in aortas and human breast carcinomas: quantitative variations with age and pathology.

Two neutral proteases have been isolated from aortas and human breast tumors. The aortic elastase-like enzyme has been further purified. The details of this purification procedure will be given and some of the properties of the purified enzyme (susceptibility to various kinds of substrates, degree of inhibition of serum inhibitors, alpha 1-antitrypsin and alpha 2-macroglobulin). This elastinolytic activity of the aorta increased with age and with the degree of atherosclerosis. Both parameters seem to act independently and in a cumulative fashion. Elastinolytic activity has been demonstrated in extracts of human breast carcinomas and is exponentially related to the age of the patient. There exists a parallel neosynthesis of elastin which increased also with the age of the patient. Some characteristics of the polymeric elastin isolated from the tumor tissue will be given. The possible role of this neutral protease present in human aortas and human breast carcinomas will be discussed.

Aging↗
PubMed1977

Elastogenesis and elastinolytic activity in human breast cancer.

Polymeric elastin was isolated and chemically characterized from 34 human breast cancers. There exists a good correlation between the histological and biochemical determinations of elastin; the breast cancer elastin resembles the other elastins isolated from ligamentum nuchae or aorta. Meanwhile it differs by its lower proline content and by its degree of crosslinking as determined by the ratio (Des + IDes/4)Lys. An elastinolytic activity (elastase) was found in human breast cancer extracts. This activity increased with the elastin content of the tumors.

Amino Acids↗
PubMed1976

[Correlation between age, arteriosclerosis and elastinolytic activity of human aorta wall].

An elastolytic protease was isolated recently from human and animal aortic wall. We report here the positive correlation between the activity of human aortic elastase, the degree of atherosclerosis and age. These two parameters appear to influence independently and in an additive fashion the level of aortic elastase. There appears to be an increasing synthesis and/or liberation of aortic elastase with age. This process is accelerated in the presence of arteriosclerosis. It appears probable that the increasing elastolytic activity is mainly responsible for the fregmentation and lysis of the elastic fibers with age and arteriosclerosis as observed with histochemical techniques.

Aging↗
PubMed1975

Isolation, purification and properties of aortic elastase.

An elastase from pig aorta has been partially purified and characterised; it exhibits immunological cross reaction with pig pancreatic elastase. Its proteolytic (k-elastin gel and polymeric elastin substrates) and esterolytic (N-succinoyl-trialanine paranitroanilide) activities as well as its degree of inhibition by serum protease inhibitors (alpha1-antitrypsin and alpha2-macro-globulin) differ sensibly from those of pancreatic elastase [14,16].

Ammonium Sulfate↗
PubMed1975

Conformational changes in fibrous elastin due to calcium ions.

A column packed with calcium-free bovine aorta elastin provided good separations of mixtures of bile salts when water was the moving phase. Tritium-labelled cholesterol was applied to the column using dilute solutions of taurodeoxycholate in Tris-NaCl buffers as solvent. The cholesterol was quantitatively eluted as a narrow peak in a rising gradient of taurodeoxycholate. When Na+ in the buffer was replaced by Ca2+ elution of the labelled cholesterol was delayed. Control experiments in which the elastin fibres were replaced as the column packing by an inert stationary phase consisting of n-butanol immobilized by silane-treated Celite showed that the effect of the change from Na+ to Ca2+ on the solvent properties of taurodeoxycholate was small and in the opposite direction. The experiments indicated that the replacement of sodium by calcium as the ionic environment of fibrous elastin produced a configurational change towards increasing hydrophobic character.

Animals↗
PubMed1975

Interaction of platelets with purified macromolecules of the arterial wall.

A method is described for the study of the interaction between human blood platelets and intercellular matrix macromolecules of connective tissues such as those found in the sub-endothelium. The method is based on the qualitative and quantitative evaluation of the elution pattern of a platelet suspension from a mixed Sepharose 2B-fibrous protein column containing standardized amounts of fibrous proteins such as elastin or structural glycoprotein-microfibrils (SGP-MF). No interaction could be demonstrated with this method between platelets and SGP-MF but there was a very distinct interaction between platelets and elastin fibers. This could be confirmed by direct microscopical demonstration of platelet clusters around elastin fibers in cryostat sections of the affinity column.

Arteries↗
PubMedDate not supplied

Expression of elastase activity by human monocyte-macrophages is modulated by cellular cholesterol content, inflammatory mediators, and phorbol myristate acetate.

We investigated the effects of a number of stimulatory agents on the production of both cell-associated and extracellular elastase-type enzymes on human monocyte-macrophages in vitro and of the modulation of such effects by modification of cellular cholesterol content. The stimulatory agents included phorbol myristate acetate (PMA) and the inflammatory mediators, lipopolysaccharide (LPS), opsonized zymosan (OZ), and platelet activating factor (PAF). Using the synthetic substrate, N-succinyl-trialanyl-paranitroanilide (SANA), we detected cell-associated elastase-like activity in monocyte-derived macrophages. Such activity increased markedly with cell maturation over the period from 5 to 15 days of adherence culture. While PAF (10 micrograms/ml) and LPS (10 micrograms/ml) were without effect on cell-associated elastase-like activity in macrophages, PMA (100 ng/ml) and OZ (1 mg/ml) markedly stimulated such activity in cells cultured for 15 days. Furthermore, a fivefold increase in the cell-associated elastase-like activity of macrophages occurred upon cholesterol loading of the cells with acetylated low density lipoprotein (AcLDL). By contrast, this activity was markedly diminished upon depletion of cellular cholesterol content after incubation with high density lipoprotein (HDL3). Latent elastinolytic activity in the culture medium was detected by use of a radioactive substrate, insoluble 3H-elastin, after initial tryptic treatment of the medium. Such latent elastase activity was secreted only by activated macrophages; the relative potency of stimulation was: PMA greater than LPS = PAF greater than OZ. Increase in cellular cholesterol content alone markedly enhanced the secretion of elastase (from undetectable levels to 28 ng of 3H-elastin degraded/hr/micrograms DNA). In all cases, both the cell-associated and secreted latent elastinolytic activities were due to metalloproteases, in view of their 90% inhibition by 2 mM EDTA. Cholesterol-loaded macrophages, which displayed an approximately 40-fold increase in total cholesterol content as compared to control cells, remained sensitive to the action of activators of OZ and PMA, while LPS and PAF exerted only weak effects. Our data indicate that cellular cholesterol content and inflammatory mediators are effective stimulants of the production and secretion of elastase-type enzymes by human monocyte-macrophages. Among these factors, cellular cholesterol content, OZ, PAF, and LPS may represent factors of relevance to the inflammatory role of the macrophage in atherogenesis and more specifically to the alteration of elastin structure in the extracellular matrix of the vessel wall.

Cells, Cultured↗
PubMedDate not supplied

Role of elastase and lysyl oxidase activity in spontaneous rupture of internal elastic lamina in rats.

Rupture of the internal elastic lamina may occur spontaneously with age in certain arteries of the rat and to various extents in different strains. This phenomenon may have some bearing on certain aspects of arterial pathology. For this study, we investigated biochemically the mechanisms of formation of interruptions in the internal elastic lamina (IIEL) by comparing aortas of Brown Norway (BN) rats, which develop numerous IIEL in the abdominal aorta, with those of Long-Evans (LE) rats, which develop none. We isolated aortic elastin from BN and LE rats and determined its amino acid composition and its susceptibility to different elastases. No differences were found between the two strains, but the quantity of elastin isolated per aorta was lower in the BN than in the LE rats. Elastase-like activity (ELA) of whole aortic extracts, measured with Suc(Ala)3NA as a substrate, was greater in the BN rats than in the LE rats of both sexes. The assay of ELA in endothelium, media, and adventitia extracted separately showed very low levels in the media compared to the endothelium and adventitia. The endothelium accounts for about one-half of the total aortic ELA, but a difference between the two strains was detected only in the adventitia. With 3H-insoluble elastins prepared from BN and LE aortas as substrates, elastinolytic activity (EA) was detected only in extracts of endothelium after prior exposure to trypsin. Extracts from BN endothelium on BN elastin were more active than were those from LE endothelium on LE elastin. The assay of lysyl oxidase activity in aortic extracts from the two strains with 3H-collagen from chick embryo calvaria as the substrate showed a lower activity in the BN than in the LE rats. Taken together, these results suggest that increased elastase activity and decreased lysyl oxidase activity may be involved in the formation of IIEL.

Animals↗
PubMedDate not supplied

Binding of 92 kDa and 72 kDa progelatinases to insoluble elastin modulates their proteolytic activation.

92 kDa and 72 kDa gelatinases, two neutral proteinases exhibiting elastinolytic activity and secreted as zymogens by aortic smooth muscle cells, were shown to bind to insoluble elastin. The active form of each enzyme interacted with substrate more avidly than latent form. Once bound to insoluble elastin, 92 kDa progelatinase was totally unaffected by any potential activators tested (tissue kallikrein, neutrophil elastase, plasmin, and stromelysin-1), except aminophenylmercuric acetate (APMA). Binding of 72 kDa progelatinase to insoluble elastin induced a fast autoactivation of the proenzyme followed by its inactivation. This process can be partly inhibited by tissue inhibitor of matrix metalloproteinases-2 (TIMP-2), EDTA and a synthetic inhibitor of matrix metalloproteinases (BB-94). Such an autoactivation process was also partially observed following adsorption of 72 kDa gelatinase to elastin-derived peptides but not to gelatin. Therefore, elastin can act as a template to direct its own proteolysis by 72 kDa gelatinase; such a mechanism could be relevant to the focal elastolysis in the arterial wall during arteriosclerosis.

Animals↗
PubMedDate not supplied

Elastase activity in cartilage extracts and synovial fluids from subjects with osteoarthritis or rheumatoid arthritis: the prominent role of metalloproteinases.

OBJECTIVE: Polymorphonuclear leukocyte (PMN) elastase is able to degrade the extra-cellular matrix components of cartilage. However, in vitro several proteinases can degrade elastin. The purpose of this study was to evaluate the role of the serine proteinases and metalloproteinases in the elastase activity measured in cartilage extracts from patients with osteoarthritis (OA), as well as in synovial fluid (SF) from patients with rheumatoid arthritis (RA) and OA. METHODS: Elastase activity was determined using synthetic low molecular weight substrates and radiolabelled insoluble elastin. Aminophenyl mercuric acetate was used to activate the prometalloproteinases. RESULTS: Elastase activity, measured using synthetic substrates, was higher in BA SF (0.76 + 0.03 microU/ml, n = 12) than in OA SF (0.14 + 0.04 microU/ml, n = 12) (p < 0.001). This activity was inhibited by metal chelating agents: 86% inhibition in OA and 75% inhibition in RA. However, in RA SF the inhibitor of serine proteinase (PMSF) also induced a 40% inhibition. Elastase activity, measured using radiolabelled elastin, in OA SF and RA SF samples and in OA cartilage extract was very low, but increased following activation by mercurial agents. Again this activity was inhibited by metal chelating agents. CONCLUSIONS: Taken together these results indicate that elastase activity (measured by standard methods) in OA and RA SF is mainly due to metalloenzymes.

Adult↗