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Biomedical subjects

A Simon

Publications and source records attributed to A Simon.

At least 451 records · Page 25Linked to original sources
PubMed1985

[The renin-angiotensin system and large arteries in the hypertensive patient].

The large arteries are impaired in uncomplicated, permanent, essential arterial hypertension. The peripheral arteries such as the humeral artery or the common carotid artery have a normal or increased diameter, reduced blood flow and, especially, reduced compliance. Reduction of the arterial compliance reflects an impairment peculiar to the large blood vessels, independent of the pressure. Antihypertensive medicines, for a given drop in pressure, may increase, diminish or not change arterial compliance. This is an important point to be taken into account in relation to cardiovascular morbidity and mortality of treated hypertensives. It has been particularly well studied in the context of inhibitors of the renin-angiotensin system.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

[Effect of arterial hypertension on pulse wave velocity and the diameter and compliance of the brachial artery in man].

The non invasive investigation of the brachial artery was performed in 51 mild to moderate essential hypertensive patients and 23 normal subjects of similar age. It included quantitative evaluation of arterial diameter (pulsed Doppler velocimetry), pulse wave velocity (strain gauge mechanography) and arterial compliance deduced from the former indices. Hypertensive patients exhibited higher pulse wave velocity (Pw 0.001) and arterial diameter (p less than 0.01) than normal controls. The strong correlation found in normal subjects between pulse wave velocity and the product of age and diastolic pressure (r = 0.88, p less than 0.001) was used as a nomogram for the analysis of those hypertensive arterial changes. Accordingly the projection of patients on this nomogram enables to distinguish two groups according to that pulse wave velocity was inside (Group 1) (37 patients) or above (Group II) (34 patients) the upper limit of the nomogram. The comparison of these two groups of hypertensive patients showed that despite a similar level of age and pressure, arterial compliance was lower and pulse pressure higher in Group II than in Group I. These results demonstrate that early alterations of brachial artery occur in hypertension: these arterial changes can be attributed in most of the patient to the exclusive effect of aging and pressure elevation; however, in some patients additional degenerative process, perhaps atherosclerotic in nature, is responsible for profound decrease in arterial compliance and increase in pulse pressure so that such patients may appear as especially predisposed to systolic hypertension and degenerative arterial complications.

Adult↗
PubMed1985

Familial occurrence of mature ovarian teratomas.

It has been suggested that genetic predisposing factors play a role in the development of ovarian teratomas. Familial occurrence of these tumors would support this view. Reported herein are identical twins, both of whom had a right ovarian mature teratoma. In both cases the presenting symptoms were acute torsion. The diagnosis was confirmed at laparotomy and subsequent histopathologic examination. The origin of ovarian teratomas seems to be linked to the process of parthenogenesis. This process probably involves a germ cell after its first meiotic division.

Adult↗
PubMed1984

Effects of sodium 2-[5-(4-chlorophenyl)pentyl]-oxirane-2-carboxylate (POCA) on carbohydrate and fatty acid metabolism in liver and muscle.

In isolated rat hepatocytes, rates of gluconeogenesis, ketogenesis and oleate oxidation to CO2 were measured at various concentrations of lactate, pyruvate and oleate in the presence or absence of sodium 2-[5-(4-chlorophenyl)-pentyl]oxirane-2-carboxylate (POCA). With increasing lactate and pyruvate concentrations, but constant oleate concentration, oleate oxidation to CO2, concomitantly to gluconeogenesis, was accelerated, whereas ketogenesis was decreased. In the presence of POCA, rates of gluconeogenesis, ketogenesis and oleate oxidation to CO2 were diminished; the concentrations for half-maximal inhibition were in the micromolar range for all metabolic processes studied. When octanoate was present instead of oleate, the inhibitory effect of POCA on gluconeogenesis was reduced and that of ketogenesis was nearly abolished, suggesting that POCA specifically inhibits the oxidation of long-chain fatty acids. In addition, the oxidation of glucose and oleate was studied in isolated rat diaphragms. POCA inhibits the oxidation to CO2 of long-chain fatty acids also in muscle tissue; the concentration for half-maximal effect, however, was about one order of magnitude higher than in liver. Concomitantly, glucose oxidation was enhanced by POCA indicating a shift in the substrate preference of energy-yielding metabolism.

Animals↗
PubMed1984

Autocatalytic inactivation of plant cytochrome P-450 enzymes: selective inactivation of the lauric acid in-chain hydroxylase from Helianthus tuberosus L. by unsaturated substrate analogs.

Lauric acid in-chain hydroxylation is inhibited in microsomes from Jerusalem artichoke tubers (Helianthus tuberosus L.) incubated with 9-decenoic, 11-dodecenoic, or 11-dodecynoic acids. 9-Decenoic acid is at best a weak competitive inhibitor of the in-chain hydroxylase, but inactivates the enzyme in a time-dependent, pseudo-first-order process with a rate constant of approximately 1.1 X 10(-3) s-1. In contrast, 11-dodecenoic acid causes a slower, time-dependent loss of the hydroxylase activity, but is a potent competitive inhibitor of the enzyme (Ki = 2 microM). Neither agent decreases the microsomal concentration of cytochrome b5, NADH-cytochrome b5 reductase, or NADPH cytochrome P-450 reductase. Cinnamic acid 4-hydroxylation, catalyzed by a cytochrome P-450 enzyme, is not affected by concentrations of 9-decenoic acid that suppress lauric acid hydroxylation. 11-Dodecenoic acid is much less specific and, at higher concentrations, markedly reduces the microsomal cytochrome P-450 content, and the hydroxylation of both lauric and cinnamic acids.

Binding, Competitive↗
PubMed1984

Fallopian tubal mucosal damage induced experimentally by Escherichia coli in the rabbit. A scanning electron microscopic study.

Pelvic inflammatory disease is the main cause of infertility due to a tubal factor. The importance of Gramnegative bacteria as major infecting organisms in pelvic inflammatory disease has been recently recognized. The predominant facultative pathogen found in tuboperitoneal fluid from women with salpingitis are coliform bacteria. This study describes an animal model for E. coli mediated tubal mucosa damage. E. coli (10(5)-10(9) bacteria 1 ml) was injected into the right Fallopian tube of sixty rabbits; the left tube injected with culture medium, served as a control. The luminal surface of the oviducts was examined by scanning electron microscope at various intervals after the injection. The degree of damage was found to be dose-dependent and maximal seven days after innoculation. The injury comprised of large areas of deciliation, severely shortened cilia, swollen and adherent throughout their entire length and disappearance of microvilli from the secretory cells. A process of regeneration began two weeks after the innoculation and was completed eight weeks later. Fertility studies carried out after completion of regeneration showed no difference in the ratio of corpora lutea/gestational sacs between the treated and control sides of individual pregnant animals. This model sheds light on the pathogenesis of tubal surface injury by E. coli and suggests that the major effects described are mediated through the endotoxin liberated from the cell wall of these bacteria and that, therefore, antibiotic treatment has no effect on the magnitude of injury. Endosalpingeal regeneration correlates well in this animal model with normal fertility suggesting that morphologic integrity of the surface epithelium may be a good criterion in assessing the reproductive capacity of the fallopian tube.

Animals↗
PubMed1984

[Subcutaneous emphysema, pneumomediastinum and dental extraction].

One case of pneumomediastinum due to subcutaneous emphysema occurring after using a high speed air turbine drill during dental extraction was described, as only a few cases have been published in the literature. Air may have entered the soft tissues directly by being forced down the gingival crevice. The air may then have passed by way of the fascial planes to enter deeper structures and the mediastinum. The consequences of this condition after general anaesthesia were discussed, more common aetiologies being tracheal or oesophageal rupture, bronchial rupture or pneumothorax.

Adult↗
PubMed1984

Concentrations of ceftriaxone in serum and lung tissue.

19 patients received an intravenous 5-min bolus injection of 2 g ceftriaxone at various times before thoracic surgery. Lung tissue concentrations of 31.8 micrograms/g could be maintained for at least 5 h. Serum and lung tissue concentrations of ceftriaxone are high enough to inhibit most organisms causing nosocomial and community-acquired respiratory tract infections.

Cefotaxime↗
PubMed1983

Thromboxane B2 in borderline and essential hypertensive patients.

Thromboxane B2 (TxB2) was measured in the venous and arterial plasma and in the urine of 15 borderline and 15 sustained essential hypertensive patients, and in the plasma and urine of 12 control normotensive age-matched subjects. Plasma and urine thromboxane B2 were significantly higher in both the borderline and sustained hypertensives than in the control normotensives. There was a significant positive correlation between urinary (i.e. renal)TxB2 excretion and the glomerular filtration rate, and between urinary TxB2 excretion and sodium excretion in the hypertensive but not in the normotensive subjects. Thromboxane A2 participates in pressure natriuresis.

Adolescent↗
PubMed1983

Comparative effects of beta-adrenergic blockade in systolic hypertension according to age.

Hemodynamic variables were measured in 34 patients with isolated systolic hypertension before and after acute administration of propranolol. The patients were separated into two groups, those younger than and those older than 45 years of age, respectively. After drug administration, systolic pressure decreased significantly (P less than 0.001) in younger subjects with a concomitant increase in rapid ejection time (P less than 0.001). In the older patients, cardiac and peripheral factors determining systolic pressure were each altered after beta-adrenergic blockade. The most striking result was the reduction in systemic arterial compliance (P less than 0.01) probably due to unmasked alpha-adrenergic vasoconstriction. This arterial effect explains the lack of systolic pressure reduction despite a decrease in cardiac performance.

Adrenergic beta-Antagonists↗