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Biomedical subjects

J Levenson

Publications and source records attributed to J Levenson.

At least 55 records · Page 3Linked to original sources
PubMed1997

Fibrinogen and its relations to subclinical extracoronary and coronary atherosclerosis in hypercholesterolemic men.

The association between plasma fibrinogen and the presence of carotid, femoral, and aortic plaque (high-resolution B-mode ultrasonography) and coronary calcium deposit (ultrafast computed tomography scanner) was determined in 693 hypercholesterolemic, never-treated men free of previous or current clinical symptoms of cardiovascular disease. The number of subjects with extracoronary disease sites and coronary calcification deposits was significantly higher in the upper than in the lower tertile of fibrinogen. Plasma fibrinogen increased according to the number of diseased sites. The odds ratio of the upper to lower fibrinogen tertile for the presence of arterial lesions was 2.6 (1.7 to 4) for carotid, 2.2 (1.5 to 3.2) for aorta, 2.2 (1.5 to 3.1) for femoral, 1.8 (1.3 to 2.6) for coronary, and 3.6 (2.3 to 6.1) for one of four diseased sites. Adjustment for age, total cholesterol, HDL cholesterol, triglycerides, current smoking, and systolic pressure slightly reduced the association between fibrinogen and atherosclerosis. A synergistic effect between fibrinogen and total cholesterol/ HDL cholesterol (TC/HDL) ratio seemed to be operating on atherosclerosis, because nearly all of the individuals (98%) had a diseased site when fibrinogen and TC/HDL tertiles were the highest. This result suggests that fibrinogen is involved in the subclinical phase of extracoronary and coronary atherosclerosis and may potentiate the atherogenic effect of hyperlipidemia.

Adult↗
PubMed1997

Incidence of extrapyramidal syndromes in AIDS patients and a comparison group of medically ill inpatients.

The authors retrospectively reviewed the charts of 29 inpatients with AIDS and 24 medically ill inpatients, all of whom were exposed to neuroleptics. Results adjusted for age, gender, type and dosage of neuroleptic, and extrapyramidal prophylaxis indicated that inpatients with AIDS were 7 times more likely to develop extrapyramidal syndromes (EPS) from neuroleptics than the comparison group of medically ill inpatients. Possible neuroanatomic, neuropathologic, and neurochemical reasons for the vulnerability of patients with AIDS to EPS are reviewed.

Acquired Immunodeficiency Syndrome↗
PubMed1997

[Ultrasonographic study of the arterial walls: application to the detection of preclinical atherosclerosis].

Ultrasonography of the arterial wall allows detection of structural (thickening, plaque) and/or functional (rigidity, reactivity) changes associated with preclinical atherosclerosis. Thickening of the arterial wall may be observed by measuring the intima-media thickness of the posterior wall of the common carotid or superficial femoral arteries. Hypertension, hypercholesterolaemia, diabetes and cigarette smoking induce carotid (and femoral) intima-medial thickening, the atherogenic nature of which however has not been clearly demonstrated. An atheromatous plaque results in a localised echogenic thickening which intrudes into the lumen and which may be assessed qualitatively by its presence or absence in peripheral arteries at risk of atherosclerosis (carotids, abdominal aorta, femorals). The number of these peripheral sites involved increases in parallel with the number of traditional risk factors in a given individual. The elasticity of the arterial walls may be evaluated at carotid or femoral levels by measuring systolo-diastolic distension by a technique known as "echotracking". The increased rigidity of the arterial wall observed in hypertension or diabetes is a marker of the sclerotic component of atherosclerosis. Arterial reactivity, dependent on changes in blood flow, is assessed by pulsed Doppler at the humeral and femoral arteries by changes in diameter induced by ischaemia/hyperameia. Changes in arterial reactivity are observed in hypercholesterolaemia even in the absence of atherosclerosis. Structural and functional changes detected by arterial ultrasonography and associated with atherosclerosis have a prognostic value which may contribute to a more accurate assessment of global vascular risk and may be useful in evaluating the efficacy of antihypertensive or lipid lowering therapy.

Arteriosclerosis↗
PubMed1996

Carotid artery and left ventricular structural relationship in asymptomatic men at risk for cardiovascular disease.

To determine whether a relationship between echographically assessed carotid artery and left ventricular (LV) structures existed in asymptomatic men at risk for cardiovascular disease, we evaluated carotid and LV parameters in 69 subjects (23-62 years) without LV hypertrophy. The right common carotid far wall intima-media thickness (IMT) was measured using an automated technique and the cross-sectional intima-media complex area (IMC-CSA) was calculated, assuming a circular profile of carotid wall layers, as (IMC-CSA = pi x IMT x (IMT + D)), D being the lumen diameter. LV mass was evaluated using the M-mode echocardiography. Among study subjects 30% were hypertensive, 67% hypercholesterolemic, 21% current smokers and 52% had a positive smoking history. In the study population LV mass correlated both with IMT (r = 0.54, P < 0.001) and IMC-CSA (r = 0.62, P < 0.001). In multivariate analysis LV mass was associated with IMC-CSA (P < 0.001), body mass index (P < 0.01), lifelong smoking dose (P < 0.01) and systolic blood pressure (P < 0.05), r2 = 0.58, P < 0.001. Therefore, IMC-CSA may be a clinically relevant independent indicator of LV mass even within its normal ranges.

Adult↗
PubMed1996

Decreased erythrocyte deformability in glycogen storage disease.

Liver glycogen storage diseases (GSD) are disorders associated with severe dyslipidaemia which can induce cell membrane alterations and possibly reduced cell deformability. Since decreased erythrocyte deformability is known to disturb blood flow in capillaries and may promote ischaemic diseases, this study was designed to investigate erythrocyte deformability using a new filtration system, the Cell Transit Analyser (CTA), and to examine lipid compounds in the blood of 23 patients affected with GSD, aged from 1 to 20 years and 18 controls aged from 1 to 17 years. The patients showed a mixed hyperlipidaemia with predominant hypertriglyceridaemia and an increase in erythrocytes mean transit times (TT) due to the presence of more rigid erythrocytes subpopulations when compared to controls. Thus the erythrocyte rigidity, in addition to the lipid abnormalities must be taken into account for long-term evolution of GSD patients. Moreover this cellular alteration may contribute to shortened erythrocyte survival.

Adolescent↗
PubMed1996

Blood lipids and rheological modifications in glycogen storage disease.

OBJECTIVES: Hyperlipidemia is a feature of liver glycogen storage disease (GSD). Recent studies have suggested that rheological mechanisms such as elevated erythrocyte aggregation may be involved in the pathogenesis of ischemic syndromes associated with hyperlipidemia. DESIGN AND METHODS: We investigated erythrocyte aggregation, lipids, and circulatory proteins in the blood of 24 patients affected with GSD, aged from 1 to 23 years (mean = 8) and 26 controls aged from 1 to 28 years (mean = 9). RESULTS: The aggregation results were much higher in patients than controls. The lipid data showed a mixed hyperlipidemia with predominant hypertriglyceridemia, low HDL-C, apoA-I and LpA-I/A-II, and high apoB as compared with controls. However, the LpA-I was not significantly different from controls. CONCLUSIONS: In conclusion, patients with GSD presented hyperlipidemia and elevated erythrocyte aggregation such that they are at long-term risk of ischemic complications.

Adolescent↗
PubMed1996

Echographic assessment of carotid and femoral arterial structure in men with essential hypertension. Group PCVMETRA.

Extracoronary in vivo structural arterial changes were studied in asymptomatic essential hypertension. Carotid and femoral arteries were examined with B-mode echography for the presence or absence of plaque (the whole vascular segments of each vessel in the both sides) and for automated measurement of the far wall intima-media thickness (the vascular segment of each vessel proximal to the bifurcation in the right side) in 53 never treated hypertensive men and 133 normotensive men similar with regard to age, serum cholesterol levels, and smoking history. In the hypertensive group carotid plaque was more frequent (P < .05) and carotid and femoral intima-media thicknesses were greater (P < .001) than in the normotensive group. In the overall normotensive and hypertensive population intima-media thickness was independently associated with age and systolic pressure in both arteries (P < .001) and with cholesterol in the femoral artery (P < .05) while plaque was associated with systolic pressure (P < .01), and cholesterol (P < .01) in the carotid arteries and with age (P < .01), cholesterol (P < .05), and smoking (P < .001) in the femoral arteries. No significant difference in intima-media thickness in both arteries existed between hypertensive subjects with plaque and those without. Wall thickening and plaque were more frequent in hypertensive patients. Thickening was distributed homogeneously to both arteries, while plaque affected preferentially the femoral bed. The influence of age and pressure was more marked on intima-media thickness than on plaque. The lack of association between wall thickening and plaque suggested that vascular hypertrophy and early atherosis might be two different structural changes.

Adult↗
PubMed1996

Cholesterol lowering therapy inhibits the low-flow mediated vasoconstriction of the brachial artery in hypercholesterolaemic subjects.

1. We tested whether lipid lowering treatment with HMG CoA reductase inhibitor modified the flow mediated large artery reactivity in primary pure hypercholesterolaemia. 2. Abnormalities in arterial reactivity have been described in the presence of high blood cholesterol, in particular an enhanced constriction of the brachial artery in response to acute induction of a low flow state. 3. Using pulsed-Doppler, we measured brachial artery diameter and flow velocity at rest and their changes induced by wrist occlusion before and after 3 months of double-blind treatment by pravastatin (40 mg orally) in 13 subjects and placebo in 15 others. 4. The significant decrease (P < 0.01) in diameter induced by wrist occlusion before (0.34 +/- 0.08 mm) placebo and pravastatin (0.39 +/- 0.10 mm) persisted after placebo (0.26 +/- 0.07 mm) but was abolished after pravastatin (0.07 +/- 0.05 mm). The absolute change in diameter induced by wrist occlusion was lower after than before pravastatin (P < 0.01) and lower after pravastin than after placebo (P < 0.05). Diameter during the wrist occlusion was higher after pravastatin than after placebo (4.35 +/- 0.16 vs 3.89 +/- 0.09 mm); P < 0.01). 5. These findings indicate that the lipid changes induced by pravastatin and/or some unknown but direct mechanism of the drug itself inhibit low-flow-mediated vasoconstriction associated with hypercholesterolaemia. Such effects may have important implications for the treatment of vasospasm often seen in the presence of high blood cholesterol.

Adult↗
PubMed1996

Hypertension promotes coronary calcium deposit in asymptomatic men.

Despite its important role in coronary disease, coronary atherosclerosis has been poorly investigated in uncomplicated hypertension. Therefore, we evaluated the presence and amount (score) of coronary calcium with ultrafast computed tomography in 73 pairs of age-matched asymptomatic hypertensive or normotensive men. We also estimated the extent of peripheral atherosclerosis as the number of arterial sites (carotid, aortic, femoral) with echographic plaque. Compared with normotensive men, hypertensive men had more frequent coronary calcium (63% versus 47%), a higher calcium score (57 +/- 111 versus 18 +/- 38), and an odds ratio of calcium deposit of 1.95 (with confidence intervals [CI] 95%, 1.01 to 3.79) for any score and of 2.38 (95% CI, 1.02 to 5.52) or 4.84 (95% CI, 1.53 to 15.3) for scores above 50 or 100, respectively. Hypertensive men showed correlations of calcium score with age and hypertension duration but not with the height of blood pressure, and the odds ratio of calcium deposit between extensive and minor peripheral atherosclerosis was 4.67 (95% CI, 1.41 to 15.45) for any score and 8.63 (95% CI, 2.10 to 35.5) or 8.13 (95% CI, 1.64 to 40.3) for scores above 50 or 100. Thus, high blood pressure and in particular its duration rather than its value promotes the presence and overall extent of coronary calcium, a potential predictor of sudden coronary death, in parallel with the extent of peripheral atherosclerosis. The mechanisms of the interaction of hypertension and coronary calcification may be multifactorial and not specific to hypertension.

Adult↗
PubMed1996

Influence of sialic acid on erythrocyte aggregation in hypercholesterolemia.

The respective role of adhesive forces induced by fibrinogen and repulsive forces induced by erythrocyte sialic acid content on erythrocyte aggregation, was investigated in hypercholesterolemic and control subjects. Aggregation index (AI) and disaggregation shear rate threshold (gamma t) were determined in the presence of either autologous plasma or dextran. Compared with controls, fibrinogen (p < 0.001) and aggregation parameters (AI p < 0.01; gamma t p < 0.01) were higher in hypercholesterolemics while erythrocyte sialic acid content (p < 0.001) was lower; in addition total serum sialic acid was increased (p < 0.01). The aggregation properties of erythrocytes, independent of plasma environment using dextran as a bridging macromolecule, showed an enhanced disaggregation shear rate threshold and an inverse relationship with erythrocyte sialic acid content. We conclude that decreased erythrocyte sialic acid content may intensify the effect of fibrinogen on aggregation and disaggregation of erythrocytes and participate in the development of atherothrombotic complications.

Erythrocyte Aggregation↗
PubMed1995

Extracoronary atherosclerotic plaque at multiple sites and total coronary calcification deposit in asymptomatic men. Association with coronary risk profile.

BACKGROUND: Recent studies have suggested that knowledge of the extent of subclinical atherosclerosis may improve prognostic information in subjects at risk of cardiovascular disease. Therefore, we tested the value of extracoronary plaque detected with echography at multiple sites and that of total coronary calcification deposit evaluated with ultrafast computed tomography for predicting the risk of coronary events estimated on the basis of traditional risk factors. METHODS AND RESULTS: We analyzed in 618 asymptomatic at-risk men the extent of extracoronary atherosclerosis, as assessed with ultrasound imaging of carotid, aortic, and femoral sites and coded as number of disease sites (none, one, two, or three) on the basis of the presence of plaque at each site, and the amount of total coronary calcification deposit, as evaluated with ultrafast computed tomography and coded as grade 0, 1, 2, or 3 on the basis of the determination of a total coronary calcium score. Concomitantly, age, systolic pressure, total and HDL cholesterol levels, current smoking, presence of diabetes, and presence of ECG left ventricular hypertrophy (ECG-LVH) were evaluated with the goal of estimating coronary risk with the use of the Framingham Study risk algorithm. The prevalence rates of at least one extracoronary disease site and coronary calcification (any grade) were high (72% and 63%). There was a strong association between the number of extracoronary disease sites and the grade of coronary calcification (P < .001). As the number of extracoronary disease sites increased, age, systolic pressure, smoking frequency, and number of risk factors increased (P < .001). As the grade of coronary calcification increased, age and systolic pressure increased (P < .001), as did the number of risk factors (P < .01). The estimated coronary risk increased with the number of extracoronary disease sites and the grade of coronary calcification (P < .001). The odds ratio of coronary risk between three and no extracoronary disease site was 2.37 (95% confidence interval [CI], 1.08 to 5.21), whereas that between grade 3 and grade 0 of coronary calcification was 1.79 (95% CI, 0.94 to 3.40). CONCLUSIONS: In an apparently healthy population, the extracoronary atherosclerotic burden as measured with multiple-site echography appears to be more powerful than the ultrafast computed tomography-detected coronary calcium burden in reflecting the multifactorial coronary risk profile. However, only men were included in the present study, and the present findings cannot be extrapolated to women.

Adult↗
PubMed1995

Role of blood pressure, uric acid, and hemorheological parameters on plasma homocyst(e)ine concentration.

Elevated concentration of plasma homocyst(e)ine is an independent risk factor for clinical atherosclerosis. In this study, the concentration of plasma homocyst(e)ine in men who lacked a history of atherosclerotic disease was correlated with hemodynamic, rheological and biochemical parameters. Hypertensive subjects had higher concentrations of plasma homocyst(e)ine than normotensive subjects. Positive correlations were found between concentrations of plasma homocyst(e)ine and several risk factors, but some of these correlations disappeared when they were adjusted for other variables. However, multivariate analyses demonstrated that systolic blood pressure, plasma uric acid, and hematocrit were predictors of concentrations of plasma homocyst(e)ine, after adjusting for certain risk factors. The possible significance of these interrelationships in atherogenesis require further study.

Blood Flow Velocity↗
PubMed1995

High-density lipoprotein subfractions as markers of early atherosclerosis. PCVMETRA Group. Prévention Cardio-Vasculaire en Medecene du Travail.

Although the inverse relation between high-density lipoprotein (HDL) cholesterol concentration and the risk of ischemic heart disease is well established, little is known about the relation of HDL subfractions HDL2 and HDL3 or lipoprotein A-I and A-I-A-II to extracoronary disease, particularly at its silent phase before the appearance of clinical lesions. We investigated the potential influence of HDL subfractions as risk markers, among the other main lipid and nonlipid risk factors, by assessing early atherosclerotic plaques detected by 3 ultrasound imaging sites in 181 hypercholesterolemic symptom-free men. No plaques were found in 36% of the patients, but plaques were found at carotid, aortic, and femoral sites in 24%, 40%, and 46% of subjects, respectively. Data were analyzed using univariate comparisons and multiple logistic regression. According to the logistic analysis, plaques were associated (1) with blood pressure (p = 0.008) and low-density lipoprotein (LDL) cholesterol (p = 0.02) in the carotid arteries; (2) with age (p = 0.0005), triglycerides (p = 0.002), and cigarette smoking (p = 0.02) at the aortic site; and (3) inversely with HDL3 cholesterol (p = 0.0008) and positively with cigarette smoking (p = 0.004), and age (p = 0.04) in the femoral site. The number of arterial sites affected (0, 1, 2, and 3) by plaques was inversely associated with HDL3 cholesterol (p = 0.001), and positively associated with smoking (p = 0.002), blood pressure (p = 0.002), LDL cholesterol (p = 0.003), and age (p = 0.006).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Wall thickening of carotid and femoral arteries in male subjects with isolated hypercholesterolemia. PCVMETRA Group. Prevention Cardio-Vasculaire en Medecine du Travail.

This study was performed to determine whether hypercholesterolemic men had increased large artery intima-media thickness (IMT), a potential surrogate measure of atherosclerosis, compared to normocholesterolemic controls. The measurements were performed in the far walls of common carotid and femoral arteries with non-invasive automatic computerized ultrasonic technique in 101 asymptomatic men (28-60 years) of whom 40 were normocholesterolemic (total cholesterol < 5.2 mmol/l, controls), 25 had borderline hypercholesterolemia (5.2 < or = total cholesterol < 6.2 mmol/l, group 1) and 36 had hypercholesterolemia (total cholesterol > or = 6.2 mmol/l, group 2). All the subjects had no other traditional risk factors, except smoking. Carotid and femoral IMT were significantly increased in group 2 (P < 0.01) but not in group 1 compared to controls. When all subjects were pooled for analysis, carotid and femoral IMT were correlated (r = 0.47, P < 0.001) and increased with total cholesterol (r = 0.35, P < 0.001) and LDL cholesterol (r = 0.33, r = 0.34, respectively; P < 0.001). Carotid and femoral IMT increased with age in each group: controls, r = 0.46, P < 0.01 and r = 0.50, P < 0.001, respectively; group 1, r = 0.42, P < 0.05; group 2, r = 0.48, P < 0.01, and r = 0.59, P < 0.001, respectively. At the carotid and femoral sites, the regression slopes between age and IMT were steeper in group 2 than in controls (P < 0.01). Thus, hypercholesterolemia was associated with diffuse large artery wall thickening, whose presence might be useful in the identification of those hypercholesterolemic individuals most prone to developing atheromatous changes, in the decision to treat, and in the monitoring of lipid-lowering treatment.

Adult↗
PubMed1995

Stratification of vascular risk in hypertension and therapeutic perspective.

Hypertension is a major risk factor for cardiovascular disease and atherosclerosis is the cause of most hypertensive complications. Therefore the detection of preclinical atherosclerosis may contribute to the better identification of hypertensive subjects at high risk of complications. Three main alterations are currently able to be diagnosed noninvasively: calcification, thickening, and stiffening of the arterial walls. Calcification of epicardial coronary arteries can be seen noninvasively by ultrafast computed tomography thanks to its rapid acquisition of image. Coronary calcification of epicardial coronary arteries can be seen noninvasively by ultrafast computed tomography thanks to its rapid acquisition of image. Coronary calcification is typical of atherosclerosis but not of stenosis. Conversely, the absence of calcification eliminates, practically, coronary artery disease as a diagnosis. Coronary calcification is present in only 63% of asymptomatic hypertensive men, suggesting that the degree of coronary atherosclerosis associated with high blood pressure varies among individuals. Wall thickening can be quantified in vivo by automated computerized analysis of ultrasonic images of the far wall intima-media complex of extracoronary vessels. Carotid and femoral wall thickening was observed in hypertensive subjects who had never been treated for hypertension compared to normotensive controls of similar age. Such vascular hypertrophy was not found in all patients, attesting to the disparity of the structural arterial changes within hypertensive subjects. Recent evidence from studies of essential hypertension suggests the lack of association between diffuse wall thickening of carotid or femoral arteries and the presence of atherosclerotic plaque (focal echogenic encroachment) in the same vessel. However, other studies in at-risk subjects suggest that extracoronary wall thickening could be related to the presence of coronary atherosclerosis, and to the incidence of coronary events. Wall stiffening is the third arterial alteration related to the sclerotic component of atherosclerosis. Its evaluation is based on the velocity of pulse wave propagation within the arterial tree or on the ultrasonic (echotracking) assessment of arterial wall distension during the cardiac cycle. Arterial stiffening is increased in the presence of hypertension, and such an increase is potentiated by the presence of other risk factors, such as smoking or hypercholesterolemia. Finally, the detection of early atherosclerosis with the above techniques optimizes the stratification of atherosclerotic risk, and may provide relevant information on comparative effectiveness of various classes of antihypertensive agents.

Antihypertensive Agents↗
PubMed1995

Reactive hyperemia unmasks reduced compliance of cutaneous arteries in essential hypertension.

To evaluate changes in distal cutaneous arteries during hypertension, we used a noninvasive method to assess the compliance and vascular resistance of the hand radial arteries, mainly distributed to the skin, in 10 normotensive and 10 hypertensive (HT) men. Radial artery diameter and blood velocity were measured by means of pulsed Doppler concomitantly with measurements of finger arterial pressure by photoplethysmography. Hand radial vascular resistance was calculated as the ratio of mean arterial pressure to mean radial blood flow. A simple resistive-capacitive model of large and small arteries of the hand allowed us to evaluate arterial compliance from the exponential slope of finger diastolic pressure decay and vascular resistance. Measurements were made at baseline and during reactive hyperemia after 5 min of complete occlusion of the brachial artery with a pneumatic cuff. Except for pressure, there were no baseline differences between the groups. In normotensive and HT subjects, hyperemia increased radial artery diameter and blood velocity (P < 0.001) and compliance (P < 0.01 and P < 0.05, respectively) and decreased mean pressure (P < 0.01 and P < 0.001, respectively) and resistance (P < 0.001). During hyperemia, the only difference between the groups, except for pressure, was lower compliance in HT subjects (P < 0.01). Moreover, compliance during hyperemia negatively correlated with baseline mean pressure (P = 0.001). Thus hyperemia unmasked reduced compliance in the HT patients but did not show abnormal resistance, suggesting that the elastic properties of the hand skin radial arteries might be more sensitive than their resistive properties to high blood pressure.

Adult↗