Biomedical subjects

C Delcayre

Publications and source records attributed to C Delcayre.

At least 37 records · Page 2Linked to original sources

PubMed1994

Angiopeptin inhibits oncogene induction in rabbit aorta after balloon denudation.

BACKGROUND: Angiopeptin, a synthetic cyclic octapeptide analogue of somatostatin, reduces neointimal hyperplasia after balloon denudation of rabbit aorta if administered before injury. The aim of this study was to analyze the effect of angiopeptin pretreatment on the level of expression of the c-fos and c-jun protooncogenes, early markers of smooth muscle cell proliferation, after balloon denudation of rabbit aorta. METHODS AND RESULTS: For histological analysis of the effect of angiopeptin on neointimal thickening after aortic balloon denudation, rabbits were randomized into three groups: group 1 (controls), twice-daily injections of saline begun 24 hours before balloon denudation (n = 9); group 2, twice-daily injections of angiopeptin 10 micrograms/kg begun 24 hours before balloon denudation (n = 9); and group 3, twice-daily injections of angiopeptin 10 micrograms/kg begun 1 hour after balloon denudation (n = 7). The degree of neointimal thickening 28 days after balloon denudation was significantly less in group 2 than in group 1 (neointimal area: group 1, 0.59 +/- 0.11 mm2; group 2, 0.22 +/- 0.05 mm2; P < .05. Neointima/media: group 1, 0.85 +/- 0.17; group 2, 0.23 +/- 0.05; P < .05). When angiopeptin was started 1 hour after denudation (group 3), however, the neointimal area (0.52 +/- 0.09 mm2) and the neointima/media ratio (0.76 +/- 0.10) were not statistically different from the control group. For analysis of protooncogene induction, rabbits received twice-daily subcutaneous injections of saline (n = 7), angiopeptin 10 micrograms/kg (n = 8), or angiopeptin 100 micrograms/kg (n = 4) begun 24 hours before balloon denudation. The animals were killed 30 minutes after balloon denudation, and total aortic RNA was hybridized with fos and jun probes. Expression of c-fos and c-jun was detected 30 minutes after injury; angiopeptin pretreatment at 20 micrograms.kg-1.d-1 induced a 41% reduction in c-fos expression and a 42% reduction in c-jun expression compared with control animals. The inhibitory effect at the higher dose of angiopeptin was similar. CONCLUSIONS: Our results show that the inhibitory effect of angiopeptin on neointimal thickening is related to events that occur very early after injury and suggest that the inhibition of smooth muscle cell activation may be responsible, at least in part, for this effect.

Animals↗

PubMed1994

Increased cardiac types I and III collagen mRNAs in aldosterone-salt hypertension.

Cardiac fibrosis is one of the deleterious events accompanying hypertension that may be implicated in the progression toward heart failure. To determine the mechanisms involved in fibrosis and the role of hemodynamic versus humoral factors, we studied the expression of genes involved in hypertrophy and fibrosis in the heart of rats treated with aldosterone for 2 months with addition of 1% NaCl and 0.3% KCl in water. This treatment induced arterial hypertension, a moderate left ventricular hypertrophy, and a decrease in plasma thyroxine. Equatorial sections of hearts from treated rats showed numerous foci of proliferating nonmuscular cells and a biventricular fibrosis. Computerized videodensitometry demonstrated an increase of collagen volume fraction by 152% and 146% and of the ratio of the perivascular collagen area and vascular area by 86% and 167% in left and right ventricles, respectively. As measured by slot blot, this cardiac fibrosis was accompanied by an increase in alpha 1-I procollagen mRNA by 75% and 160% (P < .01) and in alpha 1-III mRNA by 76% and 319% (P < .01) in left and right ventricles, respectively. Atrial natriuretic peptide mRNA was induced only in the hypertrophied left ventricle. We conclude that fibrosis is occurring and involves pretranslational regulation of collagen synthesis. Whereas hypertrophy and atrial natriuretic peptide mRNA increase are restricted to the left ventricle, fibrosis is initiated in both ventricles, supporting the hypothesis that this cardiac response is independent of hemodynamic factors.

Aldosterone↗

PubMed1993

Heparin does not inhibit oncogene induction in rabbit aorta following balloon denudation.

OBJECTIVE: Smooth muscle cell proliferation and migration are the predominant responses to intimal and medial injury after percutaneous transluminal coronary angioplasty. The in vivo inhibitory effect of heparin on these responses is well documented. To test the hypothesis that the antiproliferative effect of heparin in vivo may be related to an inhibition of proto-oncogene expression, the effects of pretreatment with heparin on the expression of the c-myc, c-fos and c-jun proto-oncogenes were examined in a rabbit model of balloon denudation. METHODS: Animals were randomised 5 h before balloon denudation to receive a subcutaneous injection of unfractionated heparin (7500 IU.kg-1, n = 7) or saline (n = 6). Total RNA extracted from the aorta 1 h after balloon denudation was analysed by northern blot technique. A histological study was also performed in saline treated (n = 4) and heparin treated (n = 4) animals 28 d after balloon denudation. RESULTS: The histological study showed that the degree of neointimal thickening was significantly less in heparin treated animals. However, the level of expression of the proto-oncogenes we studied was similar in both groups. CONCLUSIONS: Heparin inhibits neointimal thickening after balloon denudation. This inhibition is not associated with an overall decrease in the level of expression of the c-myc, c-fos, or c-jun proto-oncogenes in the arterial wall, suggesting that the antiproliferative effect of heparin may be due to an effect on other events in the cell cycle.

Animals↗

PubMed1993

Normal and hypertrophied senescent rat heart: mechanical and molecular characteristics.

The energetics of the senescent (S) rat heart and the mechanisms by which it adapts to pressure overload have been investigated by simultaneous cardiac mechanical, energetic, and molecular biological studies. Compared with young adult (YA), S papillary muscles had an improved economy of contraction since the curvature (G) of Hill's (Proc. R. Soc. Lond. B. Biol. Sci. 126:136-195, 1938) hyperbola was increased (S, 1.93 +/- 0.13; YA, 1.60 +/- 0.07, P < 0.05). In addition, the maximum unloaded shortening (Vmax) and relengthening velocities were both reduced in S. In parallel, both alpha-myosin heavy chain (MHC) and sarcoplasmic reticulum (SR) Ca(2+)-adenosinetriphosphatase (ATPase) mRNA contents were reduced (-30 and -28%, respectively), whereas beta-MHC mRNA was increased (+91%). The active tension (S, 40.0 +/- 2.6; YA, 50.1 +/- 2.5 mN/mm2, P < 0.01) was depressed although the active force remained unchanged (S, 52.0 +/- 4.0; YA, 47.5 +/- 2.5 mN). Pressure overload in senescent deoxycorticosterone acetate (DOCA)-salt rats induced a left ventricular hypertrophy (+43%) and a further decrease in both Vmax (S, 2.81 +/- 0.10; DOCA-salt, 2.55 +/- 0.13 initial length corresponding to peak of length-active curve/s, P < 0.05) and alpha-MHC mRNA (-30%) content. Senescence modifies mechanics and gene expression in a way similar to pressure overload. During senescence, an additional overload induces left ventricular hypertrophy and attenuates Vmax without worsening the economy of the contraction.

Aging↗

PubMed1993

[Restructuring of the collagen network in hypertension: role of the angiotensin-aldosterone system].

UNLABELLED: Myocardial fibrosis as a consequence of systemic hypertension is a determinant factor in alteration of cardiac function. It has been postulated that this fibrous reaction is under the influence of an elevation of blood aldosterone. To gain further insight into the mechanisms that result in an accumulation of cardiac collagen, we used a model of aldosterone-salt-induced hypertension in rat. Uninephrectomized male Wistar rats weighting 200 g were perfused with 0.75 microgram/hr aldosterone and received 1% NaCl + 0.3% KCl in the drinking water for 2 months. RESULTS: 1) Arterial hypertension was evidenced as soon as 15 days and reached 40% at 2 months. 2) The left ventricle (LV) was hypertrophied by 45% at 2 months and its relative content in mRNA coding for the beta-isoform of the myosin heavy chain was increased by 142%. 3) The microscopic examination of hemalun-eosin stained LV showed a number of important foci of proliferating non-muscular cells, of inflammatory aspect. 4) The LV collagen concentration as measured by hydroxyproline assay was not changed whereas an histological study done on Sirius red-stained slides showed that the interstitial and perivascular collagen network was more important in treated rats. 5). The abundance of mRNAs coding for the alpha 1 chain of type I collagen was increased by 60%. Our results suggest that the fibrous response involves a pretranslational regulation of collagen synthesis.

Aldosterone↗

PubMed1992

The membrane proteins of the overloaded and senescent heart.

Cardiac hypertrophy which occurs during chronic mechanical overload is one of the numerous examples of biological adaptation to environmental requirements. As such, it is obtained at random by trial and error, and adaptation represents the sum of various modifications in gene expression, including the shift in isoform of myosin or in iso Na+, K+ ATPase, the decrease in beta-adrenergic and muscarinic receptors, ryanodine channels or SR Ca2+ ATPase densities and the unchanged density in Ca2+ current. Some of these changes are beneficial at the cellular level, but are finally detrimental for the organism as a whole, as is the slowing of Vmax. It was suggested that the calcium homeostasis of the hypertrophied cardiocyte was fragile and that this modified cell was less able to buffer the changes in the intracellular calcium, thus providing a biological basis for the arrhythmogenicity of the hypertrophied heart. These various modifications may provide a new key for future pharmaceutical research.

Adaptation, Physiological↗

PubMed1992

Biological basis of diastolic dysfunction of the hypertensive heart.

To study the diastolic properties of the heart includes examining active relaxation, passive ventricular stiffness and atrial contraction. (i) The main determinant of active relaxation is the adenosine triphosphate (ATP) concentration. Relaxation needs to occur so that the ATP content of the cell can be decreased by activation of the myosin ATPase, which in turn depends upon an intracellular messenger, elevation of the calcium transient. In a model of cardiac hypertrophy active relaxation is always slower. This slowing accompanies a slowing of the calcium transient, a diminution in the activity of the Na+/Ca2+ exchanger, a change in the properties of Na+, K+ ATPase and a decreased concentration of Ca2+ ATPase in the sarcoplasmic reticulum. (ii) Chamber stiffness is likely to be increased only in relation to the degree of ventricular hypertrophy. The main, if not unique, determinant of ventricular diastolic tissue stiffness is the structure and concentration of the collagen. Consequently tissue stiffness is augmented in cardiac hypertrophy in which the ventricular collagen concentration is elevated. It is important that both clinically and experimentally cases of cardiac hypertrophy, even those resulting from pressure overload in which myocardial stiffness and cardiac collagen concentration remain unchanged, have been documented. A good example of this is the DOCA-salt model of arterial hypertension. (iii) Atrial contraction is normally more rapid than ventricular contraction, the biological basis for which is the difference in isomyosin content.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Proto-oncogene expression in rabbit aorta after wall injury. First marker of the cellular process leading to restenosis after angioplasty?

In order to study the earliest phenomenons occurring in the arterial wall after balloon angioplasty, the level of expression of the proto-oncogenes, c-fos and c-myc, was studied in rabbit aorta after balloon denudation by using Northern blot analysis. Both c-fos and c-myc are rapidly and transitorily induced (maximal at 30 min and 2 h after mechanical injury for c-fos and c-myc respectively). By comparison, infusion of norepinephrine increases oncogene expression in normal non-denuded rabbit aorta after 1 h, but the combination of both mechanical and hormonal stimuli do not lead to a more important induction than balloon denudation alone.

Angioplasty, Balloon↗

PubMed1992

Aortic perfusion pressure as early determinant of beta-isomyosin expression in perfused hearts.

Pressure overload in vivo induces an increase in cardiac protooncogene and stress protein expression that may initiate the long-term genetic changes observed in hypertrophy. To known whether mechanical stimulus is linked to specific gene transcription, expression of immediate early genes and synthesis of total proteins and myosin heavy chains (MHCs) were studied in beating and KCl-arrested isolated rat hearts perfused for 2 h under various coronary pressures. The main result of this study is that in the beating heart an augmentation of aortic pressure from 60 to 120 mmHg results in a pronounced enhancement of the synthesis of MHC (+59%) and of the expression of the beta-MHC isomyosin mRNA (iso-mRNA; +104%). Also, total protein synthesis and the amounts of poly-(A)+, c-fos, c-myc, and heat-shock protein HSP68 mRNAs were increased. To arrest the heart at 60 mmHg has no effect on total protein synthesis and on the amounts of poly(A)+, alpha-MHC and beta-MHC iso-mRNAs, and mRNAs coding for oncoproteins, but the synthesis of MHC decreased by 24%. By contrast with what we have observed in the beating heart, the augmentation of the coronary pressure in the arrested heart stimulates total protein synthesis and increases the amount of poly(A)+, c-fos, c-myc, and HSP68 mRNAs but has no effect on the expression of both MHC iso-mRNAs. In conclusion, the activation of myosin synthesis by high coronary pressure in this model has mainly a pretranslational origin when the heart is beating.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

Biological adaptation and dysadaptation of the heart to chronic arterial hypertension: a review.

Cardiac hypertrophy which occurs during chronic arterial hypertension is one of the numerous examples of biological adaptation to environmental requirements. As such, it is obtained at random by trial and error, and adaptation represents the sum of various modifications in gene expression, including the shift in isomyosin or in iso-Na+,K(+)-ATPase, the decrease in beta 1-adrenergic or muscarinic receptors or in sarcoplasmic reticulum Ca(2+)-ATPase densities, and the unchanged density in calcium channels and current. Some of these changes are beneficial at the cellular level but are finally detrimental for the organism as a whole, such as slowing of maximum shortening velocity (Vmax). The prolonged calcium transient is likely to be a consequence of the various modifications of the membranes phenotype and provides a rational basis for arrhythmogenicity of the hypertrophied heart. There are also detrimental modifications, such as the increased collagen concentration and vascular hypertrophy, which may result from the accompanying changes in plasma content in several hormones or peptides.

Adaptation, Physiological↗

PubMed1990

Beta-adrenergic agonists stimulate the synthesis of noncontractile but not contractile proteins in cultured myocytes isolated from adult rat heart.

The effect of catecholamines on adult myocardial protein synthetic activity was studied by use of an experimental model of isolated adult rat cardiac myocytes maintained in culture for 1-6 days. During this period, the majority of myocytes retained their rod-shaped morphology, but the cell number decreased progressively (50% of the initial density after 2 days in culture). Between day 1 and day 3 in culture, the specific synthetic activities of total proteins and of electrophoretically purified myosin heavy chain and actin ([14C] phenylalanine incorporation into protein, in disintegrations per minute per microgram protein) decreased (-19%,-32%, and -73%, respectively). Addition of isoproterenol or norepinephrine (10 nM) from the onset of the culture for 3 days increased the specific activity of both total and noncontractile proteins (greater than 20%) but had no effect on the specific activity of myosin heavy chain and actin when compared with 3-day cultured control cells. beta-Adrenergic receptors are specifically required to mediate this increase in total protein synthesis. This finding was demonstrated by the inhibitory effects of propranolol; neither prazosin nor yohimbine showed any effect. The pattern of synthesized protein during adrenergic stimulation was qualitatively evaluated by use of [35S]methionine incorporation and gel electrophoresis. The general pattern of labeled proteins did not differ significantly from that of control cells; this occurrence suggests that isoproterenol harmoniously stimulates the synthesis of noncontractile proteins. These findings demonstrate that low doses of beta-adrenergic agonists have an anabolic effect on adult cardiac quiescent myocytes that do not affect the major contractile proteins. Regulation of myofibrillar protein synthesis may be more dependent on myocyte contractile activity.

Adrenergic beta-Agonists↗

PubMed1989

Signal and adaptational changes in gene expression during cardiac overload.

Chronic cardiac overload stimulates various quantitative and qualitative mechanisms of adaptation, some of them being species-specific. The signals responsible for these changes in gene expression are still speculative, nevertheless early modifications of the microtubular network have been reported. Soon after overload an increased expression of various genes coding for regulatory proteins has also been observed, this includes various oncogenes and the genes of several heat-shock proteins. Hypertrophy only, is non species-specific and is adaptational because it both multiples the number of contractile units and it lowers wall stress. The slowing of the shortening velocity allows the heart to produce normal tension, at a lower cost, and has different biological explanations depending on the species. In small rodent ventricles, the main but probably not the unique, determinant of this physiological parameter is an isomyosin shift from a high ATPase activity form V1 to a low activity form V3, discovered in our laboratory in 1979. This shift has a transcriptional origin and also occurs in atria in every mammalian including humans; nevertheless it has not been evidenced in the ventricles of humans, dog, cat or guinea-pig. In these species it is necessary to take into account other mechanisms, namely those involved intracellular calcium movements. The number of total, and possibly active, calcium channels is normal in rat overloaded heart suggesting that their synthesis is activated commensurate to the development of hypertrophy. The situation is more complex for other sarcolemma proteins such as the beta-adrenergic system and the Na+, K(+)-ATPase. For the latter there is presently some evidence that an isoenzymatic shift is likely to occur, at least in rats.

Adaptation, Physiological↗

PubMed1988

Storage of phosphorylated desmin in a familial myopathy.

The quantity and the electrophoretic characteristics of desmin were analyzed in a familial skeletal muscle disorder, characterized by the intra-sarcoplasmic accumulation of an electron-dense granulo-filamentous material facing the Z-lines and reacting strongly with polyclonal anti-desmin antibodies. The analysis was performed on biopsies from the deltoid muscles of 4 patients, members of 2 families. In the 4 biopsies, an increase in the relative amount of desmin compared to that of actin or insoluble proteins (3 fold) and in the number of isovariants (6 instead of 3) was observed. The isovariants of desmin were similar to those described in Purkinje fibres of the heart as a phosphorylated form of the protein [(1987) Eur. J. Cell Biol. 44, 68-78]. Therefore, post-translational events could affect both the polymerization and the amount of desmin filaments in this autosomal dominant familial myopathy.

Adult↗

PubMed1988

Synthesis of stress proteins in rat cardiac myocytes 2-4 days after imposition of hemodynamic overload.

Isolated adult myocytes incubated with [35S]methionine were used to study the expression of proteins in the rat heart during the first 2 wk after either pressure or volume overload. In both models an early (2-4 d) and transient expression of three major stress proteins (heat shock protein [HSP] HSP 70, HSP 68, and HSP 58) was observed together with an increased synthesis of putative ribosomal proteins. Only traces of 35S-labeled HSPs were detected in controls and sham-operated animals. The three stress proteins were identified by their migration in two-dimensional gels, by comigration with HSPs, which had been induced in myocytes by incubation at 41 degrees C and immunoblot analysis using antisera directed against the 70-kD protein. Immunohistochemical staining of HSP 70 in rod-shaped myocytes and detection by immunoblot showed that HSP 70 was equally present and distributed in both sham-operated and overloaded hearts, and provided no evidence for a subpopulation of myocytes acutely involved in the increased expression of HSP 70. It is suggested that the transient expression of HSPs that occurs during the early adaptation of the myocardial cells to overload could confer some degree of protection to the actively growing myocytes.

Animals↗

PubMed1986

Microtubule reorganization is related to rate of heart myocyte hypertrophy in rat.

Since stimulation of heart hypertrophy by pressure overload was previously shown to be accompanied by a densification of microtubule network in rat heart myocytes, we verified that similar process occurred during postnatal growth in euthyroid rats and in hypothyroid rats whose growth was stimulated by 4 micrograms/day L-thyroxine (T4). For this purpose, tubulin, the constituent protein of microtubules, was immunolabeled in myocytes isolated at various times after birth. Myocyte hypertrophy was evaluated by myocyte size, the number of nuclei per cell and isomyosin expression. In hypothyroid rats, the microtubule network, which was underdeveloped, was most dense around the nucleus. During the phase of fast myocyte hypertrophy observed in euthyroid rats during late postnatal development and in hypothyroid rats after T4 administration, transient microtubule densification occurred in a myocyte subpopulation in which size was mainly determined by the rate of myocyte hypertrophy. The densification process and its kinetics resembled those observed when heart hypertrophy was induced by pressure overload. It is concluded that in rat heart myocytes undergoing hypertrophy, microtubule densification might be related to fast sarcomerogenesis, whether the stimulus is mechanical (e.g., pressure overload) or hormonal (e.g., T4).

Aging↗

PubMed1984

Unchanged myosin kinase activity in hypertrophied rat heart.

The decrease in myosin ATPase activity observed in cardiac hypertrophy induced by cardiac overload has been related to an isoenzymic redistribution of myosin. To test the hypothesis of an additional regulation of myosin ATPase through light chain phosphorylation, we measured the myosin kinase activity together in sham-operated and 50% to 100% hypertrophied rat hearts. The myosin kinase were purified approximately 600 fold with 6% yield by ion exchange chromatography and calmodulin-affinity chromatography. The presence of very important levels of proteolytic activity in the rat heart resulted in a partial loss of the myosin kinase calmodulin-dependency. The major component from both myosin kinase purified fractions was a 63 kdaltons protein. The protein content was identical in myosin kinase purified fractions from sham-operated and hypertrophied hearts. The calmodulin-dependent activity of myosin kinase, assayed in the presence of 0.1 mM Ca2+ and 10(-6) M calmodulin (about 6.6 nmol P X min-1 X mg-1), was identical in sham-operated and 50% to 100% hypertrophied hearts. Thus, myosin kinase specific activity, in these conditions, was unchanged in rat heart chronic hypertrophy. This result suggests that no direct functional relationship exists between the enzymatic properties of myosin and myosin kinase during the chronic phase of cardiac hypertrophy.

Adenosine Triphosphatases↗

PubMed1983

Phosphorylation of a 43 kdaltons protein from rat heart by a calmodulin-dependent protein kinase.

The Ca2+ -dependent phosphorylation of proteins has been recognized as a major regulatory mechanism of biological processes. In the heart, protein kinases that are activated by Ca2+ include phosphorylase kinase, myosin light chain kinase, phospholamban kinase [review in 4], and the kinases responsible for phosphorylation of endogenous proteins in the membrane [11] and soluble [6] fractions of the cell. All of these Ca2+-dependent enzymes require the presence, either as an enzyme subunit or as a cofactor, of calmodulin, a Ca2+-binding protein which is involved in various other Ca2+-requiring reactions or processes [review in 3]. We demonstrate here the presence, in the rat heart, of a soluble calmodulin-dependent protein kinase which seems different from those already described in this tissue. The substrate for this enzyme is a 43 kdaltons protein, present in the same soluble fraction.

Animals↗

PubMed1983

Immunological quantitation and localization of tubulin in adult rat heart isolated myocytes.

Isolated myocytes were purified from adult rat heart. Identification and localization of microtubules and quantitation of tubulin in these cells were performed by immunochemical procedures. Antibodies were raised against brain tubulin and purified by affinity chromatography. An enzyme-linked immunosorbent assay, ELISA, was developed for quantitation of tubulin. It allowed the measurement of 10 to 500 ng of tubulin. Tubulin content in adult rat cardiac myocytes was found to be approximately 10 micrograms per 100 mg of the total protein content. By means of a double immunofluorescence technique, the microtubule network, identified with antitubulin, was studied in reference to the sarcomeric A band labeled with antibodies specific to myosin heavy chains. The basis for identifying the microtubule network have included the use of specific antitubulin immunoglobulins and the sensitivity of the specific labeling of the network to antimitotic drugs and low temperature. It was found that microtubules were organized mainly around the nuclei, with important concentrations at the poles, showing extensions in the cone and in the cytoplasm as loosely organized loops. The shape of adult cardiac myocyte was not dependent upon the integrity of the microtubule network.

Alkaloids↗