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Biomedical subjects

L Capron

Publications and source records attributed to L Capron.

115 records · Page 7Linked to original sources
PubMed1978

Hydrolase activities in the rat aorta. II. Effects of hypertension alone and in combination with diabetes mellitus.

Hypertension is an important risk factor for atherosclerosis and often occurs in association with diabetes mellitus. Specific activities of hydrolases in homogenates of aortas from rats with renal-clip hypertension, normotension following a period of hypertension, and hypertension combined with streptozotocin-induced diabetes mellitus were measured. Enzymes included: neutral alpha-glucosidase, and lysosomal N-acetyl-beta-glucosaminidase, beta-galactosidase, cathepsin C, acid alpha-glucosidase, and acid cholesteryl esterase. After 6 or 12 weeks of hypertension, specific activities of all enzymes measured were significantly increased, levels ranging from 24% above normal for cathepsin C to 351% above normal for N-acetyl-beta-glucosaminidase. Six weeks of normotension following 6 weeks of hypertension resulted in restoration to normal of four of the six enzyme activities; the remaining two enzymes were significantly below normal levels. Combined hypertension and diabetes mellitus showed smooth muscle cell levels of four of the five hydrolases measured to be significantly lower than those present with hypertension alone. In every instance, histochemical studies of aortas showed acid phosphatase and N-acetyl-beta-glucosaminidase activities which corresponded to the biochemical findings. These findings indicate profound and discrete effects of two clinical risk factors on vascular smooth muscle cell lysosomes.

Animals↗
PubMedDate not supplied

Effects of insulin exposure upon the metabolism of rat aortic media: influence of hydrostatic forces.

When added in vitro, insulin exerts little or no effect on the metabolism of arterial media. However, indirect evidence suggests that an in vivo exposure of arterial tissue to insulin stimulates its metabolism. To evaluate the possibility that hemodynamic forces existing only in vivo may account for this difference, we studied the effect of brief (9-minute) exposures to insulin of isolated rat thoracic aorta perfused in situ at low (34 mm Hg = 4.6 kPa) and high (70 mm Hg = 9.4 kPa) static pressures. After perfusion, incorporation of glucose-derived 14C into CO2 and lipids, and production of lactate by incubated aortic tissue, were measured. At low perfusion pressure, insulin did not affect the metabolism of the media but strongly stimulated all aspects of the glucose metabolism of the adventitia. At high pressure, insulin again stimulated the adventitia but now also significantly stimulated (+66%) the synthesis of glucose-derived lipids by the media; production of CO2 and lactate by the media did not increase significantly. These results indicate that insulin directly stimulates at least one pathway of glucose metabolism by the media; and that hemodynamic forces are an important factor in determining the response of aortic media to insulin.

Animals↗
PubMedDate not supplied

Effects of injury and insulin on lipid synthesis from glucose by the rat thoracic aorta.

Chronic hyperinsulinemia is suspected of enhancing the development of arterial diseases. However, direct metabolic effects of insulin on the inner arterial wall are poorly documented. To assess the possible influence of variations in smooth muscle phenotype, we measured lipogenesis from glucose by rat thoracic aortas that had been injured with a balloon catheter. Aortas were exposed to insulin during either a 1-hour incubation or a 9-minute perfusion. Injury transiently stimulated lipogenesis by the intima-media (by 111% and 225% on the second day after injury in two separate experiments). However, insulin added either to the incubation medium or to the perfusion medium, even at a very high concentration (10(5) microunits/ml), did not modify lipogenesis by the intima-media as long as 14 days after injury. In contrast, two days after injury, the adventitia responded to insulin in a dose-dependent manner. We conclude that: 1) Injury transiently stimulates lipogenesis from glucose by the intima-media. 2) The change in smooth muscle cell phenotype, from contractile to synthetic, does not influence the metabolic sensitivity of the intima-media to insulin. 3) Our results do not substantiate the view that insulin contributes to the development of cardiovascular diseases through a direct lipogenic effect on arterial smooth muscle cells.

Animals↗
PubMedDate not supplied

[Blood pressure control after a one year follow-up in high risk subject screened in occupational medicine].

OBJECTIVE: To identify factors predicting the success or the failure of intervention on blood pressure in a population estimated at high risks. METHODS: The program "Coeur 2001" has analysed the absolute cardiovascular risk (ACVR Framingham) in 107 371 voluntary French railways employees. In the company, were considered at high risk (HR), subjects for whom risk was > or = to the 95th percentile of the distribution of the observed ACVR by age range: ACVR > or = 4.5% before 35 years, 12% between 35 and 45 years and 19% beyond 45 years, i.e. a total of 4 190 subjects. These subjects were warned about their risk and advised to choose and consult a physician. A two-year follow up was planned. Identical data (risk factors, ACVR, type of management and therapies) were collected during the first consultation with the occupational physician (T0), one year later (T1) and two years later (T2). RESULTS: Our work concerned 2376 employees at HR, consulting at T1. At T1, 54% of subjects were in the hight risk group (SHR) [48% when BP at T1 was < 140/90 mmHg and 62% when the BP was > or = 140/90 mmHg]. The mean decrease of the systolic BP (SBP) was 4 mmHg in the whole sample, 7.7 mmHg in subjects with normalised ACVR, and it remained stable in the group still at HR (-0.7 mmHg). At T0, blood pressure (BP) was > or = 140/90 mmHg in 55.8% of the patients and 38.4 at T1. This high BP was associated with higher frequency of diabetes (14 vs 7%) and overweight (BMI > or =30 kg/m2; 32.8 vs 19.7%). The percentage of treated hypertensive subjects had increased from 35 to 62% but one third of uncontrolled hypertensive subjects was treated by mono therapies at T1. CONCLUSION: To keep BP under control is a difficult task in routine medicine. At T1, despite a more aggressive treatment, 38% of subjects at high risk were still hypertensive subjects.

Adult↗