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Biomedical subjects

A Simon

Publications and source records attributed to A Simon.

At least 325 records · Page 18Linked to original sources
PubMed1992

[Hypertension has no effect on coronary calcifications in asymptomatic patients with hypercholesterolemia].

Since calcium in coronary artery walls is considered as an indicator for atherosclerosis, we used ultrafast computed tomography to quantify it non invasively in 111 hypercholesterolemic men. They were selected at worksite by a cholesterol screening program, had total cholesterol (TC) above 5.2 (6.88 +/- 0.82, SD) mmol/l, were aged from 30 to 63 (46 +/- 5 years), had never been treated with lipid lowering or antihypertensive drug, and had no clinical coronary heart disease. Body mass index, blood pressure, smoking and other serum lipids as HDL cholesterol, triglyceride (TG) were evaluated. Calcium score of proximal coronary arteries was calculated on 30 contiguous 3 mm slices from areas and peak density of calcium lesions. The mean score was 30 +/- 69 and ranged from 0 to 440. A zero score was found in 39 subjects who differed from the 72 others only by TG levels (1.44 +/- 0.60 vs 1.85 +/- 0.80; p < 0.05). A multiple regression analysis showed that elevated calcium score was associated independently to age (F = 6.6; p < 0.05) and TG (F = 6; p < 0.05) but not to blood. Thus 65% of these asymptomatic subjects had a non-zero calcium score in coronary arteries. Elevated calcium score was influenced independently by age and triglyceride level, but not by other risk factors, such as blood pressure. This potential adverse effect of moderate triglyceride elevation on large coronary arteries merits attention in the assessment of the risk of coronary heart disease.

Adult↗
PubMed1992

[Increase of erythrocyte aggregation in hypertensive men with dyslipidemia].

We have already reported that erythrocyte aggregation (EA) is increased in hypertensive subjects. To study the influence of other risk factors in EA, we have measured aggregation index IA and disaggregation shear rate threshold (gamma c) by a laser technique and the biochemical parameters in 16 normotensive normocholesterolemic subjects (NT/NCT) and 45 hypertensive subjects where 17 were normocholesterolemic (HT/NCT), 18 were pure hypercholesterolemic (HT/HCTIIa) and 10 were hypercholesterolemic hypertriglyceridemic (HT/HCTIIb). The results show that IA and gamma c are more important in HT/NCT than NT/NCT patients and much more in patients with hypercholesterolemia and hypertriglyceridemia. The cumulative effects of hypertension and hyperlipidemia merit take into consideration in pathophysiology of cardiovascular complications and could help to new strategy therapeutic developments for treatment of these complications.

Adult↗
PubMed1992

[Pseudo-neoplastic aspects of thoracic actinomycosis].

Pulmonary actinomycosis, a rare bacterial disease, is characterized by focal suppuration and an expansile fibrogranulomatous process that has a pseudotumoral evolution. On radioclinical examinations, it often mimicks an advanced or even inextractable primary bronchial tumor, thus leading to extensive surgery or even to give up the treatment. The effectiveness of antibiotic therapy leads the authors to discuss the role and limitations of surgery.

Actinomycosis↗
PubMed1992

Preparation for recertification.

Certification status in postanesthesia nursing continues for 3 years and may be renewed. Options to recertify include re-examination or completion of the Continuing Education Recognition Program. The certified postanesthesia nurse can participate in a wide range of educational opportunities to earn Continuing Education Recognition Points through this program.

Certification↗
PubMed1991

[Maculopapular rash, pruritus, upper abdominal pain, attacks of dizziness].

A 48 year old male patient presented with maculopapular rash, pruritus, peptic ulcer disease and attacks of headache and vertigo. Rubbing of the cutaneous lesions led to urticarial whealing which is indicative of abnormal mast cell proliferation in the cutis. Histologic evidence of abnormal mast cell proliferation in biopsy specimens of skin and bone marrow led to the diagnosis of systemic mastocytosis. Treatment with H1 and H2 receptor antagonists was started.

Diagnosis, Differential↗
PubMed1991

Technique for cellular microsurgery using the 193-nm excimer laser.

A new cell surgery technique has been developed to produce well-defined alterations in cells and tissue without detectable heating and/or other structural damage in the surroundings. The technique involves the use of an argon fluoride excimer laser, in the deep ultraviolet (UV) region of the spectrum at 193 nm, which is guided through a glass pipette filled with a positive air pressure. To demonstrate the method, holes were drilled in the zona pellucida of mouse oocytes. The diameter of the drilled hole was determined by the pipette tip size, and its depth by an energy emitted per pulse and number of pulses. Scanning electron microscopy of the drilled mouse oocytes showed uniform, round, well-circumscribed holes with sharp edges. Oocytes that had their zona pellucida drilled with this new method fertilized in vitro and developed to the blastocyst stage in a rate similar to that of control group. These results demonstrate the nonperturbing nature of this cold laser microsurgical procedure. In addition to the extension of our results for clinical in vitro fertilization purposes, such as enhancement of fertilization and embryo biopsy, there are wide-ranging possible uses of our method in fundamental and applied investigations that require submicron accuracy in cellular alteration.

Animals↗
PubMed1991

Spatial geometry of the dopamine innervation in the avascular area of the human fovea.

The dopamine (DA) innervation, labeled by tyrosine hydroxylase immunohistochemistry in a wholemounted human retina, is described in the avascular area of the fovea. Eleven DA neurons give rise to this innervation, among which five are interplexiform cells, so that the DA innervation consists of two plexuses: one is internal and is formed by the dendrites of all of the DA cells, and the other is external and is formed by the scleral processes of the interplexiform cells. Five concentric zones are delineated according to the focal plane in which the internal DA plexus is observed. The central zone 1 contains DA processes crossing in all directions. Zones 2 and 3 do not contain any cell bodies. In zone 3 the internal plexus begins to undergo a concentric arrangement, which is clearly observed in zones 4 and 5. The external DA innervation displays a different appearance in zones 1, 2, and 3, in which it consists of vertically oriented thin processes and terminals penetrating the outer nuclear layer, vs. zones 4 and 5 in which it consists of both the same type and horizontal processes lying in the outer plexiform layer. On the basis of DA-innervation appearance and distribution of labeled and unlabeled cell somata, it was concluded that zones 1, 2, and 3 contained the DA innervation of the foveola. DA processes filtering between photoreceptor cells are particularly well-observed in this region. This anatomical study of the DA innervation in the human fovea leads to a better understanding of the important role of DA in primate central vision and can be used as a reference for an approach of macular pathology.

Aged↗
PubMed1991

Use of arterial compliance for evaluation of hypertension.

Arterial compliance describes a change in the volume of arteries following a change in blood pressure. The physical basis of the compliance concept and experimental procedures in animals both indicate that the relation between arterial compliance and blood pressure pattern is often unclear. Compliance is pressure-dependent because of the biphasic elastin and collagen composition of arteries and, hence, decreases when blood pressure increases. Compliance also determines the pulsatile amplitude of the pressure wave by regulating the buffering function of an artery's face to the cardiac pump and, accordingly, its reduction induces a selective increase in systolic level. The questions are whether these theoretical and experimental phenomena can be extrapolated to human hypertension and whether they can be assessed from indirect measurement of arterial compliance by means of a time-domain analysis of arterial pressure and flow waves via various models of the arterial tree. Whatever the method and site of measurement, arterial compliance was found to be decreased in different forms of hypertension. This low compliance can be considered to have a causal role in elderly patients with isolated systolic hypertension. In contrast, in patients with systolo-diastolic hypertension physiologic and pharmacologic arguments exist against the fact that low arterial compliance may be the pure consequence of mean blood pressure elevation. Moreover, it is suggested that aging acts in concurrence with pressure elevation to decrease arterial compliance, and that in certain hypertensive patients additional factors, perhaps atherosclerotic in nature, contribute to impair the elastic properties of arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

Arteries↗
PubMed1991

The value of menotrophin treatment for unexplained infertility prior to an in-vitro fertilization attempt.

This work was undertaken in order to evaluate retrospectively the relative efficacy of ovulation induction by menotrophins and that of in-vitro fertilization and embryo transfer (IVF-ET) in the treatment of unexplained infertility. These two treatments were compared between two groups of patients: 87 couples undergoing 446 cycles of ovulation induction by menotrophins (group A) and 72 couples undergoing 108 cycles of IVF-ET (group B). A total of 30 and 20 pregnancies were achieved in groups A and B for a rate of 34 and 28% per patient, respectively. A similar cumulative pregnancy rate (CPR) was achieved for three cycles of ovulation induction (23%) and one cycle of IVF-ET (22%). The cumulative live birth rate (CLBR) in group A was 22% after three cycles and exceeded that of one IVF-ET cycle (17%). It is concluded that menotrophin treatment in unexplained infertility is highly beneficial and should precede an IVF attempt.

Adult↗
PubMed1991

Multiple pregnancies: risk factors and prognostic variables during induction of ovulation with human menopausal gonadotrophins.

Multiple pregnancies still constitute a major and relatively frequent complication of induction of ovulation by human menopausal gonadotrophins (HMG) despite the increasing sophistication of monitoring techniques. In order to define specific variables which may be associated with multiple pregnancies, we have compared 51 multiple pregnancy cycles to 51 consecutive control singleton pregnancy cycles, following HMG induction of ovulation. The aetiology and classification of anovulation, duration of infertility, total amount of HMG utilized per cycle and the duration of stimulation were not associated with an increase in the rate of multiple pregnancy. Basal serum oestradiol levels and its periovulatory pattern were remarkably similar in the singleton and multiple pregnancy groups. The mean age of the multiple pregnancy group (29.4 +/- 4.4 years) was significantly lower than the mean age of the singleton pregnancy group (31.6 +/- 5.3 years) (P less than 0.05). In the multiple pregnancy group, there were significantly more cycles with intermediate sized (15-17 mm). (P less than 0.002), small sized (12-14 mm). (P less than 0.02) and immature follicles (less than 12 mm) (P less than 0.03), at the time of human chorionic gonadotrophin (HCG) administration, as compared with the singleton pregnancy group. Furthermore, a direct linear correlation was observed between the number of intermediate sized follicles and number of implanted embryos. The presence of intermediate sized follicles at the time of HCG administration after HMG induction of follicular maturation is predictive of, and independently associated with, a higher incidence of multiple pregnancy.

Estradiol↗
PubMed1991

Interferon-regulated Mx genes are not responsive to interleukin-1, tumor necrosis factor, and other cytokines.

Accumulation of Mx gene products in cells of patients and experimental animals has been recognized as a useful marker for detecting minute quantities of biologically active interferon (IFN). Goetschy et al. (J. Goetschy, H. Zeller, J. Content, and M. A. Horisberger, J. Virol. 63:2616-2622, 1989) reported that not only IFNs but also interleukin-1 (IL-1) and tumor necrosis factor (TNF) were potent inducers of the human Mx genes. However, we observed no Mx induction in cultured human fibroblasts or in human peripheral blood mononuclear cells treated with various concentrations of IL-1 alpha or TNF-alpha. Mx induction was found in the spleens of mice treated with TNF-alpha or IL-1 alpha, but this effect could be neutralized with antibodies to murine IFN-alpha/beta. Of the other cytokines that we tested (IL-2, IL-6, and granulocyte-macrophage colony-stimulating factor), only IL-2 induced the Mx genes in peripheral blood mononuclear cells, but antibodies to human IFN-beta efficiently neutralized this effect. Our results thus indicate that IFNs are the only cytokines with intrinsic Mx-inducing activity.

Animals↗
PubMed1991

Assessment of elastin and collagen contribution to aortic elasticity in conscious dogs.

The elastic behavior of total elastin (EE) and collagen (EC) and the recruitment of collagen fibers (FC) supporting wall stress at a given transmural pressure level were assessed in seven conscious dogs using descending thoracic aortic pressure (microtransducer) and diameter (sonomicrometer) measurements. Stress-strain relationships values calculated at control and during bolus administration of angiotensin and nitroglycerin enabled quantification of angiotensin and nitroglycerin enabled quantification of elastic moduli of elastin (EE = 4.868 +/- 1.753 x 10(6) dyn/cm2; means +/- SD) and collagen (EC = 1,306 +/- 637 x 10(6) dyn/cm2) according to a biphasic model of elastin and collagen parallel arrangement. The FC was found to be 6.1 +/- 2.6% at a pressure level of 118 +/- 16 mmHg. Values for EE and EC were similar to those reported in in vitro studies and showed scarce variability. This approach provides a quantitative evaluation of elastin and collagen moduli in conscious animals and also permits the evaluation of FC, which may be of interest in studies of connective tissue diseases involving the aortic wall.

Angiotensin II↗
PubMed1991

Evidence for structural sympathetic reinnervation after orthotopic cardiac transplantation in humans.

BACKGROUND: Cardiac transplantation (CT) causes total cardiac denervation. METHODS AND RESULTS: To test directly for sympathetic reinnervation in humans, we measured the cardiac release of norepinephrine (NE) in response to tyramine (an agent that causes NE release from intact sympathetic nerve terminals) and sustained handgrip exercise (a reflex sympathetic stimulus) in 12 patients less than 5 months after CT, in 50 patients 1 year or more after CT, and in eight patients without CT. Plasma [NE] was measured in the aorta [( NE]Ao) and coronary sinus [( NE]CS) at rest, after tyramine administration (55 micrograms/kg, i.v.), and during sustained handgrip exercise. Cardiac NE release was determined by subtracting [NE]Ao from [NE]CS [( NE]CS-Ao). NE release was defined as [NE]CS-Ao during the intervention-[NE]CS-Ao at rest (delta [NE]CS-Ao). In patients studied within 5 months of CT, no significant NE release occurred after tyramine administration (delta [NE]CS-Ao, 33 +/- 18 pg/ml; range, -98 to 117 pg/ml) or handgrip exercise (delta [NE]CS-Ao, -34 +/- 10 pg/ml; range, -46 to 8 pg/ml; n = 10). Conversely, in 39 of 50 patients studied 1 year or more after CT, tyramine administration caused a significant cardiac NE release (delta [NE]CS-Ao, 500 +/- 59 pg/ml; range, -11 to 1,918 pg/ml), and handgrip exercise caused a significant NE release in 17 of 41 patients (delta [NE]CS-Ao, 189 +/- 34 pg/ml; range, -211 to 949 pg/ml). In normally innervated patients, tyramine caused an even larger NE release (delta [NE]Ao-CS, 1,943 +/- 210 pg/ml; range, 1,152 to 2,977 pg/ml), and handgrip exercise caused a significant NE release in two of seven patients (delta [NE]CS-Ao, 143 +/- 51 pg/ml; range, -15 to 338 pg/ml). CONCLUSIONS: Early after CT, neither tyramine nor handgrip exercise caused a significant cardiac release of NE, suggesting sympathetic denervation. Late after CT, most patients had a significant, but subnormal, NE release in response to pharmacological or reflex stimuli, suggesting that limited sympathetic reinnervation occurs in most patients after orthotopic CT.

Cardiac Catheterization↗
PubMed1991

Mechanical pressure versus intrinsic effects of hypertension on large arteries in humans.

Brachial artery diameter and compliance were measured in 23 normotensive control subjects and 49 hypertensive patients. The results were compared in isobaric conditions by a modeling analysis extrapolating from the measured data a short segment of the pressure-diameter and pressure-compliance curves in the artery. A logarithmic diameter-pressure function was used as well as measurements of brachial artery blood pressure and lumen diameter (by pulsed Doppler), and of brachial-to-radial pulse wave velocity (by mechanography). The measured values of diameter and compliance in the hypertensive patients were 109% and 63%, respectively, of the control group values. By extrapolating the data via the model at the same pressure level in all subjects (the average level of mean blood pressure of the two groups), the isobaric values of diameter and compliance in the hypertensive patients were 107% and 81%, respectively, of the control group values. Overall, measured isobaric diameters and measured compliance correlated with systolic, diastolic, and mean blood pressure values (p less than 0.001), whereas isobaric compliance correlated only with systolic (p less than 0.05) and pulse (p less than 0.01) pressure values. Thus, the increased diameter and reduced compliance of the brachial artery observed in hypertensive humans cannot be attributed solely to the stretching effect of elevated blood pressure, but also to intrinsic alteration of the arterial walls. These could represent either adaptative structural or functional changes secondary to the chronic increase in arterial pressure, or primary abnormalities of the vessel wall.

Adolescent↗
PubMed1991

Paradoxically decreased aortic wall stiffness in response to vitamin D3-induced calcinosis. A biphasic analysis of segmental elastic properties in conscious dogs.

We studied the aortic elastic behavior in response to vitamin D3-induced accelerated calcinosis in conscious dogs chronically instrumented with a pressure microtransducer and a pair of ultrasonic diameter dimension gauges in the upper descending thoracic aorta. The two functional phases of the elastic segmental properties of the aorta in vivo were discriminated by computation on a beat-by-beat basis from the phasic pressure-diameter (P-D) hysteresis loops in basal conditions and during the transient state of a wide range of pressures obtained mechanically (aortic occlusion) or pharmacologically (angiotensin bolus). The overall P-D curve formed by all P-D hysteresis loops was comprised of two linear relations according to a model that assumes that only elastin is stretched at lower pressures, whereas both elastin and collagen are stretched at higher pressures. The slope of the first linear portion of the P-D curve was considered as the elastin P-D elastic modulus, and the slope of the curve obtained by subtraction between the P-D curve and the extrapolation of the elastin straight line was assumed to be the collagen P-D elastic modulus. After vitamin D3-induced calcinosis, the elastin elastic modulus was unaffected, whereas the collagen elastic modulus decreased significantly during occlusion maneuvers (58.6%, p less than 0.01) and during bolus injections of angiotensin (37.2%, p less than 0.05). The collagen elastic modulus correlated with the serum calcium concentration (r = -0.65, p less than 0.001) and with the aortic pulse pressure (r = 0.51, p less than 0.01), and this relation persisted at constant heart rate. Histopathologic analysis evidenced calcium-depositing elastic lamina, focal disappearance of collagen, and rupture of elastic fibers. The present study shows that accelerated, severe, experimental calcinosis-inducing calcium deposition inside the large artery walls is accompanied by a clear-cut paradoxical reduction in arterial rigidity that is mainly due to functional and structural modification of collagen elasticity.

Animals↗