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Biomedical subjects

A Carayon

Publications and source records attributed to A Carayon.

At least 109 records · Page 6Linked to original sources
PubMed1985

Plasma renin activity, blood uric acid and plasma volume in pregnancy-induced hypertension.

UNLABELLED: Plasma renin activity (PRA), plasma aldosterone (PA), blood uric acid (BUA), plasma concentrations of catecholamines (Pcat) and plasma volume (PV) were measured simultaneously in 24 patients with pregnancy-induced hypertension. This hypertensive group was divided into labile (LH) and permanent hypertension (PH) groups according to the response of their blood pressure to home bed rest. As compared to normal theoretical values, PV was decreased in both hypertensive groups (LH = -70%; PH = -14%). As compared to a control group of 16 normotensive pregnant women, PRA was higher in LH and lower in PH whereas PA was lower in both hypertensive groups. In both hypertensive groups, BUA was higher than in the control group. No difference in Pcat was found between the three groups. In the PH group negative correlations were found between BUA and PRA, as well as between BUA and PV, but no correlation between PRA and PV nor between Pcat and BUA were found. CONCLUSIONS: LH and PH are two pathophysiologically different entities in pregnancy-induced hypertension. In PH, renin secretion is not appropriate to hypovolemia and therefore not primarily involved in the pathogenesis of hypertension. The role of hypovolemia in the increase of BUA may be discussed.

Female↗
PubMed1985

Testicular response to human chorionic gonadotrophin in chronic hyperprolactinaemia.

In order to evaluate the effect of hyperprolactinaemia on gonadal function in men, testicular stimulation by human chorionic gonadotrophin (hCG) (5000 IU/day, 3 consecutive days) was performed on 6 men with chronic hyperprolactinaemia and 6 control subjects. The following parameters were measured before and during the 4 consecutive days following the injections of hCG: the concentration in plasma of testosterone (T), oestradiol-17 beta (E2), dihydrotestosterone (DHT) and the urinary excretion of testosterone glucuronide (TG) and 5 alpha-androstane-3 alpha, 17 beta-diol glucuronide (3 alpha-Diol G). The rises in T, E2, DHT and the ratios of T/DHT and TG/3 alpha-Diol G were similar in both groups, but the rises in TG and 3 alpha-Diol G were lower in the hyperprolactinaemic group after hCG. There was no correlation between the response of T and the increment of E2 in either group. It is suggested that in men with chronic hyperprolactinaemia: 1) there is diminished testicular response to hCG; this could be due to chronic gonadotrophin deficiency or to a direct effect of hyperprolactinaemia on the testes, 2) there is no modulation of T synthesis through inhibition of aromatase activity and E2 secretion and 3) the 5 alpha-reduction of T is not deficient.

Adenoma↗
PubMed1985

Circulating and brain metabolites of minaprine in the baboon.

A mixture of 15N-labelled, 14C-labelled and unlabelled minaprine was administered orally to three baboons, and metabolites in blood, urine and brain investigated. Biological samples were extracted with dichloromethane and the radioactive components extracted were analysed by t.l.c. and autoradiography. Compounds identified by comparing their physiochemical properties with those of synthetic standards and by g.l.c.-mass spectrometry were minaprine, 3-[2-(3-oxo)morpholino-ethylamino]-4-methyl-6-phenylpyridazine, 3-amino-4-methyl-6-phenylpyridazine, 3-[2-(aminoethyl)ethylamino]-4-methyl-6-phenylpyridazine, p-hydroxyminaprine and minaprine N-oxide. In addition to the urinary metabolites, two circulating metabolites were detected: metabolite A, 3-[2-(3-oxo)morpholino-ethylamino]-4-methyl-6-phenylpyridazine, and metabolite B (unidentified). All circulating metabolites appeared very early in blood, confirming the rapid and extensive metabolism of the drug. Metabolites A, B and 3 (p-hydroxyminaprine) were the major metabolites present in plasma. The parent drug was not the major circulating form, and was present in a higher concentration in erythrocytes than in plasma. Erythrocytes might act as a reservoir of the drug and could explain the relatively slow blood clearance of minaprine despite its rapid metabolism. The qualitative metabolic profile in brain tissue was similar to that in blood.

Animals↗
PubMed1985

Renin angiotensin aldosterone system, urinary prostaglandins and kallikrein in pregnancy induced hypertension. Evidence for a disregulation of the renin-angiotensin-prostacyclin loop.

Plasma renin activity and aldosterone concentrations were measured simultaneously with urinary excretion of kallikrein and four prostaglandins (PGE2, PGF2 alpha, 6 keto PFG1 alpha and TXB2) in 23 patients with pregnancy induced hypertension (17 with permanent PIH and six with labile PIH, since in these latter their hypertension was controlled only by home bed rest) and in 16 normotensive pregnant women at the same stage of gestation (31 +/- 3 weeks). PRA was lower in permanent PIH than in controls and in labile PIH. No difference between the three groups was observed for plasma aldosterone and the urinary excretion of kallikrein and of the prostaglandins except that TXB2 was higher in labile PIH than in permanent PIH. Correlation studies of kallikrein disclosed correlations with most prostaglandin excretions, explained by the physiological stimulation of phospholipase A2 by kallidin. Correlation studies of PRA disclosed unexpected negative correlation with PGE2 and 6 keto PGF1 alpha in the permanent PIH group. In conclusion, labile PIH has a different biological profile than permanent PIH since they have higher PRA and higher TXB2 excretion, an association which suggests a more pronounced ureteral compression by the gravid uterus in this group. Permanent PIH has a disregulation of the renin angiotensin-prostacyclin loop since PRA and 6 keto PGF1 are negatively correlated. This suggests the role of an independent vasopressive substance which would stimulate PGI2 and suppress renin secretion.

Female↗
PubMed1984

Evidence for an angiotensin II-like material and for a rapid metabolism of angiotensin II in the rat brain.

Radioimmunoassay and radioreceptor assay for angiotensin II (AII) have been developed to detect AII-like material in rat brain extracts using HCl extraction and boiling. The amount of AII-like material found was 270 +/- 39 fmol/brain with radioimmunoassay and 67 +/- 7.8 pmol/brain with radioreceptor assay. However, chromatographic separation by gel filtration on a Sephadex G25 column revealed that this material was not authentic AII, but of higher molecular weight. Column chromatography on Sephacryl S300 combined with radioimmunoassay permitted us to show that the major part of the AII-like material had a molecular weight of about 10,000. To test the hypothesis that very rapid degradation of AII could explain the difficulty in detecting endogenous AII in the rat brain, we studied the metabolism of AII using HPLC analysis of the in vitro degradation of [3H]AI and [3H]AII (20 nM) by brain homogenates HPLC analysis showed no detectable [3H]AII generation from [3H]AI. [3H]AI and [3H]AII yielded the same [3H]metabolites corresponding to two peaks alpha and beta. Nevertheless, by adding an excess of unlabeled Ileu5-AII, which competitively inhibits AII-angiotensinase activity, it was possible to detect the formation of [3H]AII from [3H]AI. We suggest that very low levels of AII could coexist with a higher molecular weight AII-like compound in the rat brain and that very rapid degradation of AII may account for the difficulty in detecting this peptide in the brain.

Angiotensin I↗
PubMed1984

Angiotensin II in the central nervous system in the rat.

Characteristics and functional activity of Angiotensin II (AII) neuronal receptors were studied using binding and intracellular recording methods. Characteristics of AII binding allowed definition of two distinct classes of high and low affinity binding sites. The effects of AII on the electrophysiological membrane properties of neurones were investigated using cultured mouse spinal cord (SC). AII induced changes in membrane potential and input resistance which varied according to the applied concentration of peptide. These data agreed with binding results suggesting two classes of AII neuronal receptors. Although angiotensin II-like material is found in the rat brain by RIA and immunochemistry, the presence of authentic angiotensin II (AII) is a point for discussion. Using RIA and radio-receptor assay (RRA), we found AII like peptides. However, chromatographic separation by gel filtration has revealed that this material is not authentic AII but consists of compounds of higher molecular weight. The recognition of the same material, both by AII antibodies (RIA) and AII binding sites (RRA) suggests that precursors containing AII sequences exist in the rat brain. We incubated rat brain with 3H-angiotensin I (AI) at 37 degrees C and analysed the resulting 3H-peptides (HPLC). Authentic 3H-AII was not detected, but two smaller peptides appeared (peak alpha et beta). The same peaks appeared when rat brain was incubated with 3H-AII. We have only been able to reveal 3H-AII formation from 3H-AI by inhibiting AII angiotensinases with excess of AII or low temperature (22 degrees C or 12 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗
PubMed1984

[Renin-angiotensin-aldosterone system, blood volume, serum uric acid and urinary excretion of prostaglandins and kallikrein in the arterial hypertension induced by pregnancy].

The plasma renin activity (PRA), plasma volume (PV), urinary excretion of Kallikrein (UK) and PGE2, PGF2 alpha, 6-keto PGF1 alpha and TXB2 were measured in 24 ambulant patients without treatment on normal sodium diets with pregnancy-induced hypertension (HT) (diastolic BP greater than or equal to 90 mmHg, appearing after 20 weeks' pregnancy and absent 2 months after delivery). The UK was measured by an esterase technique, prostaglandins by radioimmunological assay and PV by dye dilution (Evans blue). Two subgroups of patients were identified according to the evolution of their blood pressure at rest at home; the first (7 patients) with labile HT, and the second (14 patients) with permanent HT. The PRA was significantly lower (p less than 0,001) in patients with permanent compared to labile hypertension (4,7 +/- 0,3 compared to 12,2 +/- 0,8 ng/ml/h) and compared to a control group of normotensive pregnant women (6,5 +/- 0,5). The PV, expressed as a percentage of the theoretical volume with respect to the stage of pregnancy and body surface area was low in both groups. In permanent HT: 1) there was no correlation between PV and PRA, 2) a positive correlation between UK and urinary 6-keto PGF1 alpha (r = 0,62; p less than 0,001) and PGE2 (r = -0,51, p less than 0,05). Discriminative linear analysis showed that urinary 6-keto PGF1 alpha was mainly related to PRA and to a lesser degree to UK.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗
PubMed1984

[Does the ferritin level have a practical value in chronically hemodialized patients?].

In order to determine whether serum ferritin assay has any advantages compared with usual hematologic parameters, serum ferritin was assessed in 70 hemodialysed patients. It was positively correlated with the number of blood units infused, but there was no correlation with iron treatment, serum iron or the degree of anemia. However, the interpretation of the results is difficult, because of the large dispersion of serum ferritin levels. Therefore, the determination of serum ferritin concentration cannot be recommended as a current method to follow-up and manage anemic chronic hemodialysed patients, especially when the cost of the test is taken into account.

Female↗
PubMed1983

Differences in the seasonal rhythmicity of plasma prolactin in elderly human subjects: detection in women but not in men.

Effects of age, sex and mental condition on the circadian and circannual rhythmicity of plasma prolactin in human subjects were investigated. Circannual changes were recorded on a circadian basis in January, March, June and October in four groups of subjects: seven young men, six elderly men, six elderly women and six senile demented patients (two men and four women). Blood samples were drawn every 4 h over a 24-h period at the four sampling sessions. Circadian rhythms of the hormone were validated in all groups and at all sampling sessions except twice in elderly demented subjects. The 24-h mean levels of prolactin in plasma were approximately the same in young and elderly subjects. The circadian acrophases were most often located in the vicinity of 02.00-04.00 h. The circannual rhythmicity of the hormone showed a sex difference; the rhythm was not validated in either young or elderly men but was detected in the groups of elderly women and elderly demented patients (mainly women). The acrophases were located in May. This paper strongly suggests a sex difference in the circannual rhythmicity of plasma prolactin levels in elderly subjects.

Adult↗
PubMed1983

Plasma renin activity, blood uric acid and plasma volume in pregnancy-induced hypertension.

UNLABELLED: Plasma renin activity (PRA), plasma aldosterone (PA), blood uric acid (BUA), plasma concentrations of catecholamines (Pcat) and plasma volume (PV) were measured simultaneously in 24 patients with pregnancy-induced hypertension (PIH). This hypertensive group was divided into labile (LH) and persistent hypertension (PH) groups according to the response of their blood pressure to home bed rest. Compared to normal theoretical values, PV was decreased in both hypertensive groups (LH = -7%; PH = -14%). Compared to a control group (C) of 16 normotensive pregnant women, PRA was higher in LH and lower in PH whereas PA was lower in both hypertensive groups. BUA was higher than in C in both hypertensive groups. No difference in PCat was found between the three groups. In the PH group negative correlations were found between BUA and PRA, as well as between BUA and PV but no correlation between PRA and PV nor between Pcat and BUA were found. IN CONCLUSION: LH and PH are two pathophysiologically different entities in PIH. In PH renin secretion is not appropriate to hypovolaemia and therefore not primarily involved in the pathogenesis of hypertension. Hypovolaemia may play a role in the increase of BUA in PIH.

Adult↗
PubMed1983

[Study of angiotensin II].

Radioisotopic competition of angiotensin II (A II) together with the use of structural analogues of this peptide are the two main methods of investigating the physiopathology of this hormone. Of great theoretical interest, the results of radioimmunological assay of plasma A II should be interpreted with caution because of the methodological difficulties related to its measurement and to the metabolic situation of A II. The values of the plasma A II alone do not provide additional information compared to PRA and are not representative of the pressor and biological effects of the hormone. The inhibitors of A II, although they too have a certain agonist activity, represent a method of precise investigation of the peripheral role of the hormone.

Angiotensin II↗
PubMed1981

Age- and mental health-related circadian rhythms of plasma levels of melatonin, prolactin, luteinizing hormone and follicle-stimulating hormone in man.

Circadian changes in plasma levels of melatonin, prolactin, LH and FSH were studied in four groups: seven healthy young men, six elderly men, six elderly women and six elderly demented patients (two men and four women). The daily activities of the subjects were synchronous and blood samples were taken every 4 h. The 24-h mean concentrations of prolactin in plasma were the same in all groups, whereas those of LH and FSh were twice as high in the elderly as in the young men and eight and 23 times higher respectively in the elderly women. The 24-h mean plasma levels of melatonin in the elderly were half those in the young, but were not influenced by the sex or mental condition of the subjects. A statistically significant circadian rhythm for melatonin was defined in the four groups, for prolactin in all groups except the elderly men and for LH only in the demented patients and in the young men. No circadian rhythm could be detected for FSH in any of the four groups. The acrophases of melatonin and prolactin ranged between 02.30 and 04.00 h, those of LH (when a rhythm was validated) clustered around 01.00 h. The circadian rhythms of plasma levels of melatonin, prolactin and LH are not modified in old age nor in dementia. A positive correlation has been demonstrated in young men between melatonin and LH and between melatonin and prolactin, but no such correlation could be found in the elderly.

Adult↗
PubMed1981

[Reverse or inverse reaction - a present-day point].

The reversal or inversal reactions, well studied in some research centers, is still imperfectly known, even contested or denied. This lack of knowledge has been one of the hindrances in the understanding of the mechanism of the hansenic neuritis. The evolution of the concepts about this question is studied, starting with Souza Lima and Souza Campos (1950), followed by Tajiri (1955), up to the present "I reaction" of Jopling, involving the "up grading" and "down grading" reactions. An interpretation of the reactional mechanism is given, with better possibilities for the understanding of clinical aspects and for therapy.

Antibodies, Bacterial↗
PubMed1981

[Angiotensin II and nigostriatal system (author's transl)].

The central renin-angiotensin system is implicated most importantly in the control of water balance, blood pressure and endocrine function (AVP and ACTH). Several central structures are sensitive to angiotensin II (A II), principally: the subfornical organ, the vascular organ of the lamina terminalis, the area postrema and the preoptic area. Furthermore, binding studies with radio-active ligands and also immunohistofluorescence have shown respectively the presence of A II receptors and immunoreactive material bound by A II antibodies in other central structures, and in particular parts of the motor system. In the present study, a double approach, both electrophysiological and biochemical, was used to investigate the possible role of the peptide A II in the neostriatum of the rat. 1 Microiontophoretic application of A II was shown to modify the spontaneous activity of some neurones (15/68) in the neostriatum. Generally, the action of A II was inhibitory and the inhibition was blocked by Sar1-Ileu8-A II, a specific A II antagonist. 2 Angiotensin II 10(-6) M; 10(-5) M; 5.10(-5) M) stimulated the spontaneous release of 3H-dopamine continuously synthetized from 3H-tyrosine in striatal slices of the rat. The A II-evoked release of 3H-dopamine was prevented when slices were superfused with a calcium-free medium containing EGTA. It was also suppressed in the presence of the specific antagonist Sar1-Ileu8-A II. 3 Kainic acid lesion of the intrastriatal cell bodies produced a moderate decrease of A II in the striatum (38%) whilst the activity of the converting enzyme decreased dramatically (-68%). These results suggest that there are angiotensin-containing nerve endings in the neostriatum, and that the cell bodies of such nerves are located outside this structure. Their functional role is discussed.

Angiotensin II↗