Biomedical subjects

A M Robert

Publications and source records attributed to A M Robert.

At least 19 recordsLinked to original sources

PubMed1999

Condom practices of urban teens using Norplant contraceptive implants, oral contraceptives, and condoms for contraception.

OBJECTIVES: The availability of long-acting hormonal birth control methods has created new contraceptive options for adolescents. The purpose of this study was to determine whether teens initiating these methods use condoms less frequently than teens using oral contraceptive pills or condoms alone and may therefore be at an increased risk of acquiring sexually transmitted infections. STUDY DESIGN: To investigate ongoing condom behavior in teens using levonorgestrel (Norplant) contraceptive implants, oral contraceptives, and condoms alone, we examined data from a 2-year prospective cohort study of 399 urban teens. The study consisted of 3 clinic-based cohorts of adolescent female contraceptive users: Norplant contraceptive implants (n = 200), oral contraceptives (n = 100), and condoms alone (n = 99). Data were collected at an admission interview and at 1- and 2-year follow-up from method continuers. RESULTS: Norplant contraceptive implant users were less likely than oral contraceptive or condom users to report condom use at last sex or consistent condom use at 1- and 2-year follow-up. The implant group showed a significant decrease in condom use from admission to 2 years after method initiation. The proportion of implant users self-reporting new sexually transmitted infections at 2-year follow-up, however, was not significantly greater than that of oral contraceptive or condom users. CONCLUSIONS: Our findings indicate that teen users of Norplant contraceptive implants are less likely to use condoms than teens who choose oral contraceptives but, probably because of differences in sexual behavior, are no more likely to self-report sexually transmitted infections. Our findings also indicate that teens who choose oral contraceptives and condoms do not use them consistently enough to avoid pregnancies or sexually transmitted infections.

Adolescent↗

PubMed1998

Elastin-elastase-atherosclerosis revisited.

This review proposes reinvestigation of a topic studied in the author's laboratory over the last decades concerning the age-dependent modifications of the vascular extracellular matrix (ECM) as related to atherogenesis and its recognized risk-factors: blood lipids, lipoproteins. Most salient previous results are confronted with recent publications in this field. Age-dependent modifications of the vascular wall discussed in this review include upregulation of elastolytic enzymes, demonstrated for the first time in the vascular wall in this laboratory, matrix biosynthesis and receptor function. The progressive deposition of lipids in elastic tissues as well as the addition of lipoproteins or lipids to cell and organ cultures were shown to modify matrix biosynthesis and upregulate elastase expression. Lipid-elastin interactions exhibit a great deal of specificity as shown by the nature and amount of lipids accumulating in elastin in vivo and in vitro. Recent epidemiological studies (the EVA study) enables the confrontation of blood lipid parameters with matrix related components (serum elastase and inhibitors, elastin peptides, fibronectin) in the same blood samples. The elastin laminin receptor present on vascular cells was shown to trigger NO dependent vasodilation, and downregulation of cholesterol synthesis. Both of these functions decrease or disappear with age except the upregulation of elastase release which is preserved and increased. Recent experiments extended these findings to T-lymphocytes present also in the atherosclerotic plaque. Finally several recent publications are analyzed which give more precision on the cellular mechanisms underlying the above-described modifications.

Adult↗

PubMed1998

Preliminary data on the age-dependent decrease in basic fibroblast growth factor and platelet-derived growth factor in the human vein wall and in their influence on cell proliferation.

The roles of basic fibroblast growth factor (bFGF) and platelet-derived growth factor (PDGF) in vein disease and aging were investigated. Smooth muscle cells from human saphenous veins were cultured. The age dependence of bFGF and PDGF activation of the smooth muscle cell proliferation was determined, and the bFGF and PDGF contents in vein wall homogenates were measured by an enzyme-linked sorbent assay. There were morphological alterations in the cells with more polygonal and polynucleated cells in cultures from aged donors, similar to those observed in vitro in aged cell cultures. Some cultures did not reach confluency after the tenth passage, suggesting early decay of the cultures from diseased veins. bFGF and PDGF stimulated the proliferation of the vein smooth muscle cells, but only in cultures treated with hyaluronidase. This stimulation decreased with the age of the donor. The amount of the two growth factors in human vein walls decreased with donor age. The amount of bFGF decreased faster (slope: 3.3138 ng/mg DNA/year) than that of PDGF (slope: 1.021 ng/mg DNA/year). This results in an age-dependent change in the bFGF/PDGF ratio from 4 mol/mol at the age of 20 years to 1 mol/mol at the age of 80. These growth factors also modulate the synthesis of extracellular matrix components. The continuous change in the bFGF/PDGF ratio may alter the composition of the extracellular matrix of the vein wall during aging and thus its susceptibility to varicose disease.

Aging↗

PubMed1998

Extracellular matrix and blood-brain barrier function.

The blood-brain barrier (BBB) is a functional characteristic of the cerebral microvasculature that determines which molecules can travel from the bloodstream to the brain parenchyma and vice versa. During the last few decades, we have investigated the contribution of vascular extracellular matrix (ECM) to BBB function. The present review analyzes our findings in the light of recent data on age-related brain function alterations and discusses the potential contribution of BBB function impairment to the processes that determine these alterations.

Animals↗

PubMed1997

Pathology of unstable plaque: correlation with the clinical severity of acute coronary syndromes.

OBJECTIVES: The aim of this study was to relate the various clinical presentations of acute coronary syndromes to the underlying plaque morphology as assessed from histopathologic analysis of plaque fragments obtained by directional coronary atherectomy (DCA). BACKGROUND: Autopsy studies have shown that unstable angina and infarction are related to plaque instability and involve events such as fissure or rupture of the fibrous cap, thrombosis and inflammation. The clinical severity and prognosis of acute coronary syndromes can be estimated by the Braunwald classification of unstable angina. Whether plaque morphology can be related to the Braunwald classification has not been evaluated. METHODS: Plaque fragments were obtained by DCA in 75 patients: 38 with unstable angina, 19 with stable angina and 18 with no symptoms after infarction. The presence of fibrous tissue, thrombus, high cellularity, inflammatory cells, atheroma, neovessels and "stellar-shaped" smooth muscle cells was evaluated in 7-micron thick sections by appropriate staining. The patients were classified according to clinical presentation without knowledge of the results of pathologic examination, and a plaque instability score was assigned. The risk of further cardiac events was classified as low, medium or high. RESULTS: Increasing severity of the score of unstable angina was associated with increasing prevalence of thrombus, high cellularity, atheroma and neovessels. Plaque from patients with unstable angina considered to be at low risk of further events appeared very similar to that of patients with stable angina, whereas the specific morphologic characteristics of plaque instability were more frequently observed as the clinical score and the risk of further events increased. After thrombolyzed infarction, plaque morphology depends on the delay between the acute event and DCA. Within 1 week after infarction, plaque still showed the morphologic characteristics of instability, whereas late DCA provided samples with morphologic features similar to those observed in patients with stable angina. CONCLUSIONS: The morphologic features of plaque fragments vary at different stages of acute coronary disease. The specific features of plaque instability correlate with the clinical scoring system of the Braunwald classification.

Adult↗

PubMed1997

Synthesis of glycoconjugates by human diseased veins: modulation by procyanidolic oligomers.

Venous diseases become steadily more common and severe with age, and are often accompanied by venous lymphatic oedema. We have investigated the role of glycoconjugates in this disorder and the action of procyanidols used to treat these diseases. Explants of vein wall from patients with or without venous lymphatic edema were cultured for 24 hours and the incorporation of radioactive glucosamine into total glycoconjugates and into hyaluronan was measured. The explants from patients with oedema incorporated more glucosamine than those without oedema (+42% expressed as c.p.m./mg dry weight into total glycosaminoglycans and +12% expressed as c.p.m./mg dry weight into hyaluronan). The explants from oedematous patients secreted less glycoconjugates into the culture medium than those from non-oedematous veins (-63% of total incorporated radioactivity into hyaluronan and -66% into hyaluronidase-resistant glycoconjugates). Explants placed in medium containing procyanidols (1 mg/ml, 2.8 mM) incorporated less glucosamine (-19%) and secreted more into the medium (+119%). Glycoprotein and sulphated glycosaminoglycan synthesis were mainly affected which may well explain the beneficial effect of procyanidols on vein disorders.

Adult↗

PubMed1997

[Hyaluronic acid (hyaluronan) levels in pathological human saphenous veins. Effects of procyanidol oligomers].

We investigated the hyaluronan content in the pathologic human venous wall using an ELSA assay with hyaluronectin according to the method of Delpech et al. The mean hyaluronan content in the 74 fragments from 12 venous walls studied was 596 +/- 528 ng/mg dry weight. These 12 venous walls could be separated in 3 distinct groups according to their hyaluronan content, low (277 +/- 141 ng/mg dry weight), moderate (552 +/- 361 ng/m dry weight) or high (1299 +/- 568 ng/mg dry weight). The differences between these groups are significant (p < 0.001). The presence of a veino-lymphatic oedema was generally associated with a high hyaluronan level (in 65% of cases). The 3H-glucosamine incorporation in cultured venous wall explants showed a 35% increase (p < 0.002) in varicosis as compared with the non or less modified segments of the vein and a 29% (p < 0.001) increase in presence of a veino-lymphatic oedema. The addition of 1 mg/ml of PCO (Procyanidolic Oligomers) to the culture media induced near to 20% decrease of the 3H-glucosamine incorporation and a 34% decrease of the hyaluronan content. Our results confirm the role of local overproduction of hyaluronan in the establishment of oedema and the potential effect of PCO to counteract it.

Age Factors↗

PubMed1997

[Aging and brain circulation. Role of the extracellular matrix of brain microvessels].

Maintenance of normal brain activity is dependent among other factors on the maintenance of a functional blood-brain barrier (BBB), localised mainly at the capillary wall of cerebral microcirculation. The modifications of the BBB during aging play an important role in cognitive decline with aging as well as in dementias. A review of the experiments of our laboratory over the last decades is presented, on the interaction of endothelial cells with their basement membranes, both together representing a functional unit of BBB. The action of proteolytic enzymes on the basement membrane increases BBB permeability by increasing the transcellular transport activity of endothelial cells. Flavonoid drugs protect BBB from proteolytic activity by interacting with collagen fibers and protecting sensitive peptide bonds from attack by proteolytic enzymes. These drugs enhance also the resynthesis of degraded basement membranes.

Aging↗

PubMed1996

[Effect of anthocyanins on human connective tissue metabolism in the human].

BACKGROUND: Diabetic retinopathy can lead to blindness. This is due to an abnormally increased synthesis of connective tissue in order to a) repair leaking capillaries and b) formation of new capillaries. METHOD: Twelve adult diabetics were treated with 600 mg anthocyanosides per day for two months. Samples of gingiva tissue were taken before and after treatment. Incubated with radio-active labeled amino acids, the measure of radioactivity from different connective tissue extracts can show a changed protein biosynthesis activity. RESULTS: The use of radio-active labeled amino acids show significant decrease of biosynthesis-activity of connective tissue especially polymeric collagen and structure-glycoproteins by anthocyanoside medication. CONCLUSIONS: Anthocyanosides help to prevent diabetics from injuries caused by malfunction of synthesis-activities throughout normal diabetic medical treatment.

Administration, Oral↗

PubMed1996

Presence of the elastin-laminin receptor on human activated lymphocytes.

A variety of cells - fibroblasts, vascular smooth muscle cells, endothelial cells, monocytes and polymorphonuclear leukocytes (PMNs) - carry the elastin-laminin receptor. The activation of this receptor by elastin peptides triggers a variety of reactions as chemotactic movements to an elastin peptide gradient, release of lytic enzymes and oxygen-free radicals, modifications of ion fluxes. We now show that human lymphocytes also express this receptor. Membrane labelling of the receptor by specific antibodies shows capping. In the presence of elastin peptides lymphocytes show increased proliferation and increased production of an elastase type serine protease apparently identical to PMN-elastase, inhibited by cycloheximide and by anti-PMN elastase antibodies. T-lymphocytes are present in atherosclerotic plaques where elastin degradation occurs and could contribute to the chronicity of the lesion by the above mechanism.

Cell Division↗

PubMed1995

[Effect of benzquercin on the connective tissue of lathyritic mice. Optic and electron microscopic study].

Vascular pathology is characterized by important alterations of some vessel macromolecular constituents, such as fibrous proteins, collagens and elastin. The purpose of our study was to establish the activity of benzquercin treatment on such alterations of the vascular wall. As experimental model we used lathyrism induced in mice by chronic administration of beta-amino-propionitril (beta-APN). This compound prevents crosslink-formation in elastin and collagen and provokes a disorganization of the structure and an alteration of the physiological functions of the vascular wall. The connective tissue of the skin is also impaired simultaneously with that of the blood vessels. We compared by optical and transmission electron microscopy the morphological structure of the aorta and the skin of 3 groups of mice: a normal control group, an other which only received the beta-APN alone and a third one which received the beta-APN and the benzquercin treatment. The second group, injected with beta-APN without treatment, showed important alterations of the structure of the aorta as well as of the skin. Both fibrous proteins, collagen and elastin were concerned by these alterations, the consequence of which was an increase of the permeability of the aorta wall demonstrated with the horse-radish peroxydase as a tracer. The third group, injected with beta-APN and treated with the benzquercin, showed much less morphological disorders than the untreated group and the vascular permeability was also close to normal controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Aminopropionitrile↗

PubMed1995

[Role of glycosoaminoglycans in venous disease. Mode of action of some flavonoid drugs].

Varicose vein walls differ from normal venous walls by an important loss of their collagen content and an increase of their glycosaminoglycan content, essentially of hyaluronan. The decrease in fibrous protein content can be attributed to increased proteolytic (collagenolytic) activity as well as to free radicals. Glycosaminoglycan increase reflects a disregulation of the normal program of matrix biosynthesis by the cells of varicose vein wall, essentially smooth muscle cells. Some flavonoid drugs are capable of correcting these deviations by decreasing proteolytic attack on fibrous proteins and the accumulation of proteoglycans and hyaluronan. These effects, due to interactions between flavonoid drugs and the cells and fibrous proteins of the venous wall differ according to the nature of such drugs. A hypothesis is proposed to explain these differences in the intensity of action of flavonoid drugs with apparently closely related structures, based on the conformation of these drugs and their interaction with the triple helical structure of collagen fibers as well as with the cell membranes.

Antihypertensive Agents↗

PubMed1994

Retarded fibronexus formation and cell attachment on type V collagen.

We previously found that type V collagen repressed the attachment and spread of aortic smooth muscle cells. The present study was carried out to investigate the effects of type V collagen on the formation of fibronectin and F-actin filaments of human dermal fibroblasts in relation to cell attachment and spread, using an immunofluorescent technique and morphometry. The number and area of the cells attached to type V collagen at 1 and 3 hours after seeding were significantly lower than those of cells on other substrates, including collagen types I, III and IV, and bovine serum albumin. However, there was no significant difference in the attachment and spread among the cells on these substrates after 24 hours. Cultured fibroblasts exhibited two patterns of fibronectin; one was a clear, linear fibronectin localized mainly in the cellular margins, and the other was a granular or flocculent fibronectin found in the perinuclear areas. The former was stained in non-permeabilized cells, but not in trypsin-treated cells (cell surface fibronectin). In contrast, the latter was not detected in nonpermeabilized cells, but was found in trypsin-treated cells (perinuclear fibronectin). Most of the cells cultured on type V collagen did not form either linear cell surface fibronectin or F-actin filaments at 3 hours. In contrast, many cells on collagen types I, III, and IV developed both cell surface fibronectin and F-actin filaments, the distributions of which were partially coincident. Colocalization of linear cell surface fibronectin and F-actin filaments was found in cells on all of the substrates after 24 hours. Perinuclear fibronectin showed similar patterns, and was not colocalized with F-actin filaments on different substrates at 3 and 24 hours of culture. Solid-phase substrates induced a better cellular attachment at 3 hours than serum adhesive factors. The administration of monensin, which inhibits the secretion of protein products, decreased the intensity of the fluorescence of cell surface fibronectin in fibroblasts, which was observed in a clear line. These results suggest that the retardation of the initial attachment and spread of fibroblasts on type V collagen is related to an inhibition in the formation of the fibronexus, a close transmembranous association of individual fibronectin fibers and F-actin filaments.

Actins↗

PubMed1993

[Histomorphometric changes of the skin in rats in relation to age].

Histomorphometric evolution of skin was studied using 74 Wistar rats aged from 2 days to 34 months. Epidermal and dermal thickness, as well as surface density of collagen bundles in the superficial dermis was investigated by image analysis. Average epidermal thickness decreases progressively up to the 4th week, than it remains almost constant. Dermal thickness has a biphasic evolution. It increases rapidly during the first 3 weeks (+166%). This increase is followed by an important decrease (-55%), than dermal thickness increases again and reaches at the age of 1 year 5 times its value at birth. That thickness persists up to the end of life. Surface density of collagen bundles follows the rate of increase of dermal thickness, but variations are less important. Total increase of surface density of dermal collagen bundles between birth and the end of life corresponds to 56% of the initial value.

Age Factors↗

PubMed1991

[Development with age of the cutaneous microdepression relief. Correlation with the alteration of cognitive performances].

The evolution of the skin microdepressionary network has been quantified as a function of age on negative replicas by semi-automated image analysis in two populations. The first one was composed of 190 healthy persons from 6 months to 95 years of age. There is a good correlation between the age of the subjects and the 4 stereological parameters of the geometrical figures delimited by the primary and secondary skin folds. Some differences between males and females could be observed concerning the rythm of the evolution of the studied parameters. In a second population of 111 persons (72 females and 39 males) of more than 65 years of age and followed in an epidemiological study ("PAQUID", J. F. Dartigues et al.), we compared the results of the evaluation of the 4 parameters of the cutaneous microdepressionary network with the age of the subjects and with the results of cognitive function tests (MMS of Folstein, Wechsler's test). Some of the stereological parameters seem to be better correlated to the score of MMS than to the chronological age of the subjects.

Adolescent↗

PubMed1991

[Study of the effect of procyanidole oligomers on cultured mesenchymatous cells. III. Size and form of cells and nuclei. Quantitative morphologic study].

The effect of procyanidole oligomers (PCOs) on the morphology of cultured human skin fibroblasts (FB) and swine aorta smooth muscle cells (SMC) was studied. Exposure to PCOs induced dose-dependent changes in the size, shape and arrangement of cultured fibroblasts. Smooth muscle cells did not exhibit similar changes. These findings demonstrate that procyanidole oligomers interact with fibroblasts membrane and cytoskeletal constituents. With smooth muscle cells the main site of action of procyanidole oligomers may be the basement membrane surrounding the cells, which is lacking in fibroblasts. Thus, in addition to their action on extracellular matrix constituents, i.e., collagen and elastin fibers, procyanidole oligomers affect structural components of cells, i.e., the cell membrane and cytoskeleton. This twofold action of procyanidole oligomers on mesenchymatous cells and their extracellular matrix may be a significant component of the pharmacologic action of procyanidole oligomers.

Adolescent↗

PubMed1990

Skin thickness changes in normal aging skin.

The age-dependent decrease of skin thickness was studied with a morphometric procedure on upper inner arm skin biopsies. Epidermal thickness decreased somewhat faster in men (7.2% of the original value/decade) than in women (5.7%). The total dermal thickness decreased at about the same rate in men and women (6%/decade). The thickness of the superficial layer of the dermis exhibited a biphasic evolution with age and these variations were not significantly different between men and women because of the large individual variations. This may be due partially to the difficulties of delineating with precision the limit between superficial and reticular dermis. These results are somewhat lower than those obtained by physical measurements of skin thickness. This may be due to fixation artifacts and also to the overestimation of skin thickness by physical measurements.

Age Factors↗

PubMed1990

Age-related changes of the human skin surface microrelief.

In the present study we describe an original semi-automated image analysis method to quantitate the changes of the geometric properties of cutaneous microrelief with age. The skin surface is composed of very fine lines intersecting each other and forming polygons. The number, average size, perimeter and equivalent diameter of these polygons were quantified on replicas of 190 persons, 101 females and 89 males, from 6 months to 95 years of age. A good correlation was found between the age of the subjects and these four parameters. The evolution of these parameters was not linear but could be best described by a polynomial equation of fourth order for the number of polygons per field, and by an exponential equation for the three other parameters: average surface, perimeter and equivalent diameter of the polygons. A few details of the evolution with age of the skin surface patterns were different for males and females.

Adolescent↗