PubMed Health⌕ Search

Biomedical subjects

M P Jacob

Publications and source records attributed to M P Jacob.

At least 55 records · Page 3Linked to original sources
PubMed1990

Determination of elastin peptides in normal and arteriosclerotic human sera by ELISA.

The degradation of elastin during various pathological processes such as emphysema or arteriosclerosis was demonstrated by several investigators. In the present work, we adapted an ELISA technique for the determination of elastin peptide (EP) levels in human sera and plasma, in healthy and arteriosclerotic subjects. This test makes use of human aorta elastin hydrolyzed by a chemical procedure (kappa-elastin) instead of EP produced by pancreatic or leukocyte elastase. Polyclonal antibodies to this antigen were obtained in rabbits. The indirect ELISA procedure is sensitive, specific and reproducible. No correlation could be demonstrated between EP level and anti-EP antibody concentration of IgG or IgM types determined in the same serum samples. These antibodies did not interfere with EP determinations. EP concentration did not change with age in control subjects. In obliterative arteriosclerosis of the legs and in type IIb hyperlipoproteinemia, EP levels showed a marked increase, while in hypertension, ischemic heart disease and diabetes mellitus, the increase was moderate. In stroke, only slight changes were observed. In type IV hyperlipoproteinemia, EP levels were lower than in controls.

Adult↗
PubMed1989

Identification and signal transduction mechanism of elastin peptide receptor in human leukocytes.

The existence of a novel receptor on human polymorphonuclear leukocytes (PMNLs) and monocytes was demonstrated, named soluble elastin peptide receptor. Soluble elastin peptides, like K-elastin, which are liberated from elastin fibres, can be found in the sera, and they possess several biological activities such as chemotaxis. Studying the effects of elastin peptides on leukocytes, it was found that: (i) the elastin peptide stimulates the oxidative burst, the intracellular free Ca2+ elevation through a specific receptor; and (ii) in the signal transduction mechanism of this elastin peptide receptor, the phosphatidylinositol breakdown is involved.

Adult↗
PubMed1989

Elastonectin and the elastin receptor.

Two different types of interactions were described between cells and elastin: 1) the adhesion of cells to insoluble fibrous elastin and 2) the binding of soluble elastin derived peptides by cells. We could show that these are two different mechanisms underlying those two types of interactions. The adhesion of cells to elastin fibers is mediated by a cell-membrane complex with a 120 kD protein as the main adhesive compound which we proposed to designate elastonectin. Three other proteins (67, 60 and 45 kD) were coisolated with elastonectin. Adhesion of insoluble elastin to mesenchymal cells (fibroblasts, smooth muscle cells) is inducible with soluble elastin peptides. Highly metastatic Lewis lung carcinoma cells and human melanoma cells also exhibited the adhesion mechanism, but without a lag phase (constitutive adhesion). Binding curve (Scatchard plots) obtained with radiolabelled elastin peptides indicated the presence of high affinity elastin receptors on mesenchymal cells and human white blood cells (monocytes and PMNs) with Kd-s in the nanomolar range. The binding of elastin peptides triggers several cellular reactions such as chemotaxis, Ca++ influx (increase of Ca++i) and with mononuclear blood cells release of lytic enzymes and oxygen radicals. All these cells which exhibited elastin receptor function also exhibited adhesion although the two processes could be inhibited selectively. The receptor action is mediated by a G-protein-phospholipase-IP3 mechanism, involved in the increase of intracellular Ca++. It appears that this action also triggers the biosynthesis and membrane localization of elastonectin. The coupling of these 2 mechanisms between receptor and adhesion appears to be modified in transformed cells.

Cell Adhesion↗
PubMed1989

Determination of anti-elastin peptide antibodies in normal and arteriosclerotic human sera by ELISA.

We adapted a highly sensitive and reproducible ELISA technique for the determination of anti-elastin peptide antibodies of IgG type AEAb-IgG) and IgM type AEAb-IgM) in human sera. The determination was performed in the sera of 265 normal and diseased persons. The pathologies studied included obliterative arteriosclerosis of the legs, ischemic heart disease, stroke, diabetes mellitus, type IIb and IV hyperlipoproteinemia and hypertension. No clearcut correlation could be found between AEAb and age. In contrast, in arteriosclerotic patients and especially in obliterative arteriosclerosis of the legs and ischemic heart disease, the concentration of AEAb-IgG was significantly increased. The AEAb-IgM showed no change in the studied diseases. Both types of AEAb were decreased in type IV hyperlipoproteinemia. Anti-elastin antibodies may be involved in the pathomechanisms of the above diseases and the determination of antibody concentrations may be of some help in obliterative arteriosclerotic diseases.

Adult↗
PubMed1988

Effect of elastin peptides and N-formyl-methionyl-leucyl phenylalanine on cytosolic free calcium in polymorphonuclear leukocytes of healthy middle-aged and elderly subjects.

The effect of elastin peptides (kappa-elastin, KE) and N-formyl-methionyl-leucyl-phenylalanine (FMLP) on cytosolic free calcium in polymorphonuclear leukocytes (PMNLs) of healthy middle-aged (35-45 years) and elderly (greater than 60 years) patients with normal and high serum cholesterol level was investigated. The cytosolic free calcium [( Ca2+]i) elevation after stimulation with these compounds was decreased in PMNLs of the aged groups compared to the healthy middle-aged group. The guanine nucleotide binding regulatory Gi protein inhibitor, pertussis toxin (PT) prevented the enhancing effect of KE and FMLP on PMNL free calcium of healthy middle-aged subjects, but could not completely abolish the [Ca2+]i elevation in PMNLs of aged subjects.

Adult↗
PubMed1987

Prevention by calcitonin of the pathological modifications of the rabbit arterial wall induced by immunization with elastin peptides: effect on vascular smooth muscle permeability to ions.

Immunization of rabbits with elastin peptides prepared from purified bovine ligamentum nuchae elastin produces calcified arteriosclerotic lesions and fragmentation of elastic lamellae. Simultaneous administration of porcine calcitonin largely prevents the development of lesions. Experiments were carried out to clarify the mechanisms involved in the development of lesions as well as those involved in the preventive effect of calcitonin. Control experiments were carried out using bovine serum albumin (BSA) as antigen. Circulating antibodies and soluble immune complexes increased steadily in the sera of animals immunized with elastin peptides or BSA. The cellular immune reaction was weak as assessed by [3H]thymidine incorporation into lymphocytes in the presence of antigen or phytohemagglutinin. Arterial lesions appeared only in the animals immunized with elastin peptides, not in those immunized with BSA. Ion flux measurements were also carried out on strips of aorta obtained from immunized and control animals. Immunization with elastin peptides significantly increased the ouabain-insensitive 22Na+ efflux, the 86Rb efflux (indicator of K+ efflux), and the 45Ca2+ influx. Simultaneous calcitonin administration prevented the increase in Ca2+ influx but did enhance passive permeability to Na+ and K+ as well as the sodium pump. When calcitonin was administered without immunization, it decreased arterial smooth muscle permeability to Na+ and K+ and also decreased the basal Ca2+ influx. It is concluded that the pathological modifications of the arterial wall triggered by immunization with elastin peptides is at least partly mediated by the effect of antielastin antibodies and immune complexes on the ion permeability of arterial smooth muscle. Prevention of the increased Ca2+ influx by calcitonin is probably a key effect in the prevention of the development of lesions. The fact that calcitonin alone can modify the ion permeability of arterial smooth muscle suggests that this hormone may play a role in the regulation of vascular homeostasis.

Animals↗
PubMed1987

Immunology of elastin: study of anti-elastin peptide antibodies by DOT immunobinding assay.

In order to further investigate the role of the immune system in the arteriosclerotic process, we investigated the anti-elastin peptide antibodies (AEAb) of the IgG and IgM types by DOT immunobinding assay in the sera of patients suffering from various arteriosclerotic diseases. In total 232 control and pathological sera were studied. In obliterative arteriosclerosis of the legs 90%, ischemic heart disease 67% and hypertension 60% of sera were positive for AEAb of the IgG type independent of age. In the case of diabetes mellitus, however, the duration of the disease was determinant. In rheumatoid arthritis, the results were negative. No clear-cut positivity could be demonstrated in stroke patients either. These results indicate that AEAb can be detected in some diseases and DOT appears to be an appropriate method for the AEAb screening in various diseases.

Adult↗
PubMed1987

Effect of elastin peptides on ion fluxes in mononuclear cells, fibroblasts, and smooth muscle cells.

Elastin peptides prepared by alcoholic potassium hydroxide degradation of highly purified fibrous elastin from bovine ligamentum nuchae (kappa-elastin) were shown to act on the ion channels of human monocytes, aorta smooth muscle cells, and skin fibroblasts. In small amounts (between 0.1 and 1 microgram/ml), elastin peptides strongly increased calcium influx and inhibited calcium efflux by an apparently calmodulin-dependent mechanism. They also were shown to increase sodium influx and to decrease rubidium influx in monocyte preparations obtained from human blood. Only the ouabain-sensitive portion of rubidium influx was inhibited. The action of elastin peptides is strongly concentration-dependent; the maximal activity observed in the above reactions was less than 1 microgram/ml. These results suggest that elastin peptides may play a role in the regulation of the biological activity of mesenchymal cells, in the proximity of which they are released by the action of elastase-type enzymes. Such enzymes were demonstrated in aorta smooth muscle cells (membrane-bound serine protease) and in fibroblasts (metalloprotease). Monocytes and polymorphonuclear leukocytes were also shown to carry elastase-type enzymes. The release of peptides from elastin by elastase-type enzymes and the action of such peptides on the ion fluxes through the cell membrane may well be involved in mechanisms of the modulation of the phenotype of mesenchymal cells during aging as well as in the development of age-dependent pathologies such as arterioclerosis.

Adult↗
PubMed1986

Effect of elastin peptides on human monocytes: Ca2+ mobilization, stimulation of respiratory burst and enzyme secretion.

The effect of elastin peptides (Kappa-elastin) was investigated on human monocytes. The data presented here indicate that elastin peptides increase the intracellular Ca2+ level measured by Quin 2 fluorescence and mediate the release of beta glucuronidase and elastase. The O2 consumption and H2O2 release were stimulated in a dose-dependent manner. The early rise of cAMP was followed by a return to the original level at 30 min and by a concomitant increase of cGMP level. The action of elastin peptides on intracellular calcium level and cGMP levels may well be related to its previously demonstrated chemotactic activity. These activities may well play a role in the modifications of the extracellular matrix following elastin degradation as observed in atherosclerosis, emphysema and aging.

Calcium↗
PubMed1986

Physicochemical and ultrastructural properties of cholesterol esters bound to elastin.

Physicochemical and ultrastructural properties of cholesterol ester complexes of fibrous elastin and of K-elastin were studied using differential scanning calorimetry (DSC) and electron-microscopy. The number of molecules of the different fatty acids retained in these elastin complexes varied between large limits according to the nature of the fatty acid of the cholesterol ester, ranging from 0.1 microgram/200 mg of elastin for cholesterol arachidonate to 48 micrograms/200 mg elastin for cholesterol palmitate. The ultrastructural studies confirmed the association of cholesterol esters with fibrous elastin and soluble K-elastin. The DSC-data showed that the temperature of transition between the crystalline and the liquid crystalline state shifts towards higher temperatures (well above body temperature) when cholesterol esters are bound to elastin: no liquid crystalline mesophase was observed in cholesterol oleate or linoleate-elastin complexes at 37 degrees C; melting of the crystalline structures took place at 51 degrees C and at 42 degrees C for the cholester Holeate and linoleate-elastin complexes respectively. These results indicate that in the elastin-bound form the crystalline-liquid crystalline transition is inhibited. The "stabilization" of the crystalline structure of cholesterol esters by fibrous elastin may be of biological significance and account for the crystalline deposits seen in advanced atherosclerotic lesions at sites of elastic fiber breakdown.

Calorimetry, Differential Scanning↗
PubMed1984

Ultrastructural and biochemical modifications of rabbit arteries induced by immunization with soluble elastin peptides.

Immunization of rabbits with soluble elastin peptides (kappa 1-elastin) in complete Freund's adjuvant resulted in morphological and biochemical modifications in aorta and in lung arterioles. The elastic fibers of both tissues appeared fragmented at the light microscopical and ultrastructural levels. The presence of IgG at the site of lysed elastic fibers could be evidenced by immunological techniques. In agreement with these findings, a significantly increased elastase-type protease activity could be demonstrated in aorta extracts from the immunized animals as compared to those obtained from control animals. The biosynthetic activities of aorta explants of rabbits immunized with kappa 1-elastin maintained in organ culture conditions were considerably reduced, as shown by the decrease of incorporation of [14C]lysine and [14C]glucosamine in aorta macromolecules. These results show that anti-elastin antibodies may well be involved in the pathological modifications of the arterial wall and especially in the triggering of the degradation of elastic lamellae.

Animals↗
PubMed1984

Interaction between elastin and elastases and its role in the aging of the arterial wall, skin and other connective tissues. A review.

Elastic fibers are progressively lysed during maturation and aging and in an accelerated fashion in several aging diseases such as diabetes, arteriosclerosis, emphysema and several skin diseases. Several enzymes (elastase-type proteases) were isolated in recent years in our laboratory which appear to be involved in these processes. A cell membrane bound serine protease was isolated from arterial smooth muscle cells and was shown to increase with in vitro aging of the cells. A metallo-protease was isolated from skin fibroblasts and was shown to be capable of attacking the constituents of elastic fibers, mainly the microfibrillar glycoproteins and also the desmosine cross linked elastin in vivo. This partially purified fibroblast enzyme was shown to attack these elastic fibers when injected into the dermis. A new selective staining procedure was used to visualise and quantitate, by computerized image analysis, the skin elastic fibers in normal and pathological human or animal skin biopsies. This method, combined with the injection of elastase in rabbit skins, alone or together with inhibitors, enables the ex vivo/in vivo study of elastase action (and of its inhibition).

Adult↗
PubMed1982

Variation of elastase-type protease activity and elastin biosynthesis in rabbit aorta induced by cholesterol diet and immunization with elastin peptides.

Elastase-type proteases were shown to be produced by arterial smooth muscle cells and fibroblasts in culture and are probably involved in the development of the arterio-atherosclerotic process (1-4). The present investigation was aimed at the quantitative determination of the elastase-type enzyme activity in the aortas of rabbits submitted to two different athero-arteriosclerosis inducing treatments: high cholesterol diet and immunization with kappa-elastin peptides. Simultaneously we determined the incorporation of 14C-lysine in cross-linked elastin peptides by the surviving aorta extracts, determined with a synthetic substrate (Suc-(Ala)3-pNA) increased two fold after 1.5 month cholesterol diet, and three fold after 8 weeks of immunization with kappa-elastin in complete Freund's adjuvant. The incorporation of 14C-lysine in cross-linked elastin slightly increased (+20%) in cholesterol-fed aorta-explants and strongly decreased (-65%) in the immunized aorta-explants, on a DNA basis. These results confirm our contention that atherogenic stimuli produce an increase of elastase-type enzyme activity in the arterial wall. This increase appears to be correlated with elastic fibers degradation. It may also be accompanied by a decrease of elastin biosynthesis as in the kappa-elastin induced immuno-arteriosclerosis model.

Animals↗
PubMed1981

Pharmacological studies on elastin peptides (kappa-elastin). Blood clearance, percutaneous penetration and tissue distribution.

Soluble elastin peptides obtained by partial hydrolysis of ligamentum nuchae elastin in 1M KOH in 80 per cent aqueous ethanol (kappa-elastin) were labelled in vitro by incubation with tritiated borohydrate. 3H-labelled kappa-elastin was administered iv and percutaneously and its elimination and organ distribution determined. iv administered kappa-elastin is rapidly eliminated through the kidneys with a first rapid phase (t 1/2 9.9 min) and a second slower phase (t 1/2 169 min). Percutaneously administered elastin peptides penetrate in the dermis and 30 to 40 per cent of the administered label can still be found in the skin 48 hours later. Resorption through the skin is a slow process, with very little or no radioactivity detectable at any time in the blood. Only liver and lung contained significant amounts of radioactivity (4 per cent and 2 per cent of the total dose administered) at 48 hours after administration. Urinary elimination represented about 5 per cent of the administered dose. Histochemical studies performed on the skin of rats treated daily with kappa-elastin (25 mg per day for 4 weeks) showed an increase of elastin-staining material in the dermis. This increase is partly due to a modified staining of collagen bundles, resulting probably from the association of elastin peptides with the collagen bundles. It may also partly be due to an increase of elastin fibers in the dermis through the stimulation of fibroblast activity. These histochemical results confirm the penetration of elastin peptides in the dermis, their association with dermal collagen fibers and also their action on the cellular activity of the dermis.

Administration, Topical↗
PubMedDate not supplied

Age-dependent changes of K-elastin stimulated effector functions of human phagocytic cells: relevance for atherogenesis.

Effector functions of the elastin receptor on human phagocytic cells from young and older individuals were studied. In cells of young healthy subjects the elastin peptides, the agonists of receptor, stimulated both superoxide anion release from PMNs and phagocytosis of coated human red cells by monocytes. Elastin appeared to inhibit the cholesterol synthesis in monocytes, measured by the incorporation of 14C-acetate. In comparison with phagocytic cells of young (< or = 25 +/- 6 years) subjects. PMNs of elderly donors (> or = 75 +/- 10 years) bore a similar number of binding sites for soluble elastin peptides, and the affinity of the elastin receptor was unchanged as shown by Scatchard analysis. The phagocytosis of coated human red cells stimulated by elastin peptides was also similar in the two age groups. However, several differences were found between phagocytic cells of young and elderly donors 1) PMNs of elderly released increased amounts of elastase from both resting and elastin peptide stimulated cells, and 2) monocytes of elderly showed a lack of inhibition of cholesterol synthesis by elastin peptides when maintained in cholesterol-free medium. These changes in effector functions of phagocytic cells from elderly donors might contribute to the age-dependent increase of susceptibility to the development of atherosclerotic lesions.

Adult↗
PubMedDate not supplied

Effect of elastin peptides on vascular tone.

Elastin peptides are present in human blood. As elastin receptors exist on several cell types, especially endothelial cells, this investigation was carried out to study the effect of elastin peptides on vascular tone. For this purpose, rat aortic rings were mounted in an organ bath for isometric tension measurements. Elastin peptides (kappa-elastin) were added in the concentration range of 0.1 ng/ml to 1 microgram/ml, concentrations similar to those found in the circulating blood. In rat aortic rings, precontracted or not with noradrenaline (10(-6) M), elastin peptides induced an endothelium-dependent vasodilation. The pretreatment of aortic rings with N-omega-nitro-L-arginine methyl ester (10(-5) M), an inhibitor of nitric oxide (NO) production, or with indomethacin (10(-5) M), an inhibitor of cyclooxygenase, prevented elastin peptide-induced vasodilation. These findings suggest that elastin peptides act through the synthesis of prostanoids, leading to the production of NO. Moreover, this relaxant effect of elastin peptides was decreased or inhibited when aortic rings were treated with lactose (10(-5) to 10(-2) M) or laminin (10(-6) to 10(-4) mg/ml) whereas lactose or laminin was unable to inhibit acetylcholine-induced vasodilation. These findings suggest that the inhibitory effects of lactose and laminin are specific for elastin peptide receptors and are in agreement with previous studies on these receptors. As there is evidence of the degradation of elastin in several vascular diseases, the concept that elastin peptides may contribute to the control of vascular tone is discussed.

Animals↗