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Biomedical subjects

F Pala

Publications and source records attributed to F Pala.

At least 19 recordsLinked to original sources
PubMed1999

Double-blind randomized placebo-controlled study of transdermal estrogen replacement therapy on hypertensive postmenopausal women.

We investigated the effects of transdermal 17beta-estradiol, combined with standard antihypertensive therapy, on the modification of the cardiovascular risk profile in hypertensive postmenopausal women. In a randomized, double-blind, placebo-controlled study, we enrolled 200 postmenopausal women with mild to moderate hypertension. Patients received 17beta-estradiol (50 microg/day, transdermal) and norethisterone acetate (2.5 mg/ day, orally) or placebo. At baseline serum total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, glucose, and fibrinogen plasma levels were measured and all subjects underwent complete M-mode and 2-D echocardiograms, which were repeated after 6, 12, and 18 months of hormonal replacement therapy. Compared with placebo, all values decreased significantly except for HDL cholesterol. In both groups, no modifications were observed in echocardiographic parameters, except for left ventricular mean diastolic and systolic wall thickness and left ventricular mass index, which showed a significant decrease in both groups. The reduction was greater in the treated group; the percentage of patients with left ventricular hypertrophy was 46% before randomization and 17.2% after 18 months of treatment (P < .0001), whereas in group II the percentage was 48% at baseline and 31.5% after 18 months (P < .05). In conclusion, transdermal 17beta-estradiol, associated with antihypertensive therapy, may contribute to the reduction of cardiovascular risk profile in hypertensive postmenopausal women.

Administration, Cutaneous↗
PubMed1993

Different sensitivity to hydrochlorothiazide and to potassium-canrenoate among essential hypertensive patients.

We compared the response of blood pressure (BP) to either K-Canrenoate (K-Can) or hydrochlorothiazide (HCTZ) in 26 mild-to-moderate essential hypertensives in a double-blind, cross-over design over 2 months each. The dose was 12.5 mg o.d. for HCTZ and 50 mg o.d. for K-Can: dosing was doubled after 1 month if seated diastolic BP was > or = 95 mmHg. Eight pts were "selective responder" to the lowest dose of HCTZ (HCTZ-R), and 6 to K-Can (K-Can-R). Seven pts had their high blood pressure controlled by the highest dose of both drugs and 4 were insensitive to both. One pt dropped out during HCTZ for low plasma K+, and 3 during K-Can (nausea and dizziness: 2 pts; plasma creatinine rise: 1 pt). All these side effects were reverted after drug withdrawal. HCTZ-R and K-Can-R differed for PRA (1.4 +/- 0.6 vs 0.8 +/- 0.4 Ang I ng/ml/h, p < 0.05) and Na-K-Cl cotransport (230 +/- 39 vs 372 +/- 24 mumolNa/L RBC/h, p < 0.01). Our data suggest the existence of a subgroup of essential hypertensives surprisingly insensitive to HCTZ, characterized by a "low" PRA and by a Na(+)-K(+)-Cl- cotransport higher than the HCTZ-R. Their selective response to K-Can suggest a peculiar pathogenetic mechanism underlying their high blood pressure.

Blood Pressure↗
PubMed1991

Effect of angiotensin converting enzyme inhibition on the menstrual cycle of hypertensive women.

Angiotensin II was reported to play a key role in ovulation in rats and it seems also to be involved in the regulation of LH release. Thus, we studied the effect of chronic ACE inhibition on the menstrual cycle, measuring daily plasma estradiol, progesterone, LH and FSH, and renin and prorenin before and during the third month of treatment with enalapril (10 mg b.i.d.) in 10 mild essential hypertensive women. Blood pressure was normalized by treatment. The cyclical changes of steroids and gonadotrophins were unaffected in their temporal relationships and in the magnitude of their variation during the experimental cycle compared with the basal cycle. A synchronization of plasma prorenin with the other hormones was seen both before, as previously reported, and during enalapril treatment. Our data show that peripheral blockade of angiotensin I conversion does not affect the pituitary guidance of the ovarian hormonal response or the ovarian prorenin release during the menstrual cycle. Our data are in agreement with the hypothesis that circulating angiotensin II does not play a key role in the human fertility process and that hydrophilic ACE inhibitors can be safely used in the treatment of hypertensive women of reproductive age.

Adult↗
PubMed1991

Prorenin is present in human red blood cells.

We looked for the presence of prorenin in erythrocytes from normal subjects (n = 8), hypertensive patients (n = 8), and pregnant women (n = 8). Angiotensin I generation was measured at 37 degrees C, pH 5.7, in the presence of homologous substrate (1400 ng/mL) before and after trypsin activation (100 micrograms/mL) in (A) haemolyzed erythrocytes, (B) supernatants of haemolyzed erythrocytes, and (C) in the sixth washing of erythrocytes diluted 1:1 with a 0.1 M Tris buffer containing 0.5% bovine serum albumin and protease inhibitors. Haemolyzed erythrocytes generated angiotensin I only after trypsin treatment, and the rate of generation was the same (A) before and (B) after centrifugation at 20,000g, indicating the absence of prorenin bound to the cell membranes. When aliquots of the last washing of erythrocytes (C) were tested for angiotensin I generation before and after trypsin, they did not generate angiotensin I, indicating that residual prorenin from the plasma was no longer present in our preparation. Angiotensin I generation by trypsin-treated A and B was completely abolished by preincubation with anti-renin serum. The level of prorenin was not significantly different in the erythrocytes from normal, hypertensive, and pregnant subjects (68 +/- 10, 58 +/- 7 and 107 +/- 17 pg angiotensin I.mL-1.h-1, ns) in spite of their very different plasma levels (21 +/- 2.5, 17 +/- 2.4 and 110 +/- 12 ng angiotensin I.mL-1.h-1, p less than 0.01 for pregnant women compared with both normal and hypertensive subjects). Our data show that prorenin is present in human erythrocytes in fairly constant and clearly detectable amounts, thus suggesting a possible intracellular role for it.

Adult↗
PubMed1990

[Effect of menstrual cycle hormones on cation transport in the red-cell membrane].

Erythrocyte cation transport, plasma prorenin and renin and sexual hormones were sequentially evaluated in 12 normal volunteers over the menstrual cycle. Na-K cotransport and Na-Li countertransport raised in 6 out of 12 subjects in synchronization with the ovulatory phase. When the maximal % variation (ovulatory phase) versus baseline (follicular phase) of the Na-K cotransport was plotted versus the maximal % increment of oestrogens. A direct, highly significant inverse correlation was observed (r = 0.904, p less than 0.001). Moreover, a highly significant inverse correlation between plasma prorenin and intraerythrocyte Na (r = -0.857, p less than 0.001) in the follicular phase was found. Our data suggest that erythrocyte cation transport can be influenced by sexual hormones in human.

Adult↗
PubMed1990

[Effect of chronic enalapril treatment on prorenin, renin and sex hormones during the menstrual cycle in patients with essential hypertension].

Since angiotensin II seems to be involved in the process of ovulation we studied the effect of chronic enalapril on plasma prorenin, renin, estradiol, progesterone, LH and FSH during the menstrual cycle in ten essential hypertensive women. Our data show that peripheral blockade of A I conversion does not affect the pituitary guidance and the ovarian hormonal response of the menstrual cycle and, we can speculate, that it does not interfere with the process of ovulation.

Adult↗
PubMed1990

[Protective effect of a calcium antagonist against renal vasoconstriction induced by endothelin in the normotensive rat].

We studied the effect of nifedipine, a dihydropyridine calcium antagonist, on the hemodynamic changes induced by endothelin, in awake normotensive rats. Endothelin (0.07-1.40 nmol/kg, e.v.) caused an initial hypotensive effect, followed by long lasting hypertension. Renal blood flow was reduced immediately and still remained below basal levels, at 30 minutes after endothelin injection. Nifedipine (1 mg/kg, i.p.) significantly prevented the effect of endothelin on mean blood pressure and induced a right-ward shift in the dose response curve of renal hemodynamic changes induced by endothelin. We conclude that treatment with calcium antagonist could be very useful in all those conditions in which systemic and regional vasocostriction is provoked by endothelin.

Animals↗
PubMed1989

Circulating prorenin and renin in response to intravenous adrenocorticotrophic hormone in essential hypertension.

Plasma prorenin and renin changes after a bolus injection of 25 U intravenous adrenocorticotrophic hormone (ACTH, synacthen) were studied in seven untreated uncomplicated essential hypertensives over a period of 24 h. Plasma prorenin did not change significantly during the study, whereas renin after 24 h was higher than at baseline (4.3 +/- 0.6 versus 2.3 +/- 0.9 ng angiotensin I (Ang I)/ml per h, P less than 0.01). We conclude that endogenous glucocorticoid stimulation induced by exogenous ACTH and ACTH itself seem to induce a secondary or tertiary rather than a primary effect on the human renin gene.

Adrenocorticotropic Hormone↗
PubMed1989

Correlates of atrial natriuretic factor in chronic renal failure.

Plasma atrial natriuretic factor (ANF), blood pressure, age, plasma renin activity and creatinine were measured in 50 normal volunteers, 141 essential hypertensives, 35 patients with chronic renal failure who had never been dialysed and 27 patients with end-stage renal failure on constant haemodialysis. Plasma ANF was correlated positively with age in the normal group (r = 0.52, P less than 0.01) and with blood pressure in the essential hypertensives (r = 0.50, P less than 0.001), and negatively with renin in the normal and end-stage renal failure patients (r = -0.47, r = -0.34; P less than 0.01, P less than 0.05, respectively). When patients without left ventricular hypertrophy were matched for age and blood pressure, plasma ANF was significantly different between the essential hypertensives and the normal and end-stage renal failure patients (16 +/- 1, 38 +/- 6 and 148 +/- 24 pmol/l, respectively; P less than 0.001). Cardiac factors are therefore not the only determinant of circulating plasma ANF in humans with chronic renal failure.

Aging↗
PubMed1989

[Erythrocyte cation transport in arterial hypertension: interrelation with the renin-angiotensin-aldosterone system and the atrial natriuretic factor].

Red cell membrane Na(+)-K+ transport systems, renin-angiotensin-aldosterone system (RAAS) and atrial natriuretic factor (ANF) were studied in a group of 50 mild essential hypertensive patients (n = 25 for each group) age, sex and blood pressure matched. Na(+)-K+ ATPase and intracellular Na+ (Na+ i) were significantly different between the two groups (p less than 0.01). A slight difference was also seen for the Na(+)-K+ cotransport (p less than 0.05) as a likely consequence of the differences in the methodology of Na+ charge to study its efflux from the red cells in vitro. A negative correlation (r = -0.47, p less than 0.01) was observed between ANF and Na(+)-K+ cotransport suggesting an interrelationship of the two systems in the homeostasis in body fluid and electrolytes.

Adult↗
PubMed1989

Activation of human prorenin by lipidic constituents of the cell membrane.

Activation of semipurified human kidney prorenin was found to occur in vitro in presence of a mixture of lipids that mimics the composition of the inner human cell membrane. The lipid-dependent activation was indeed only partial (38 +/- 4%) when compared to that obtained by trypsin in liquid phase (100 micrograms/mL) used as a control of maximal activation (100%) under our experimental conditions (semipurified human kidney prorenin in presence of semipurified human plasma renin substrate at a concentration of 1400 ng/mL, at pH 7.2). The phenomenon was time-dependent up to 60 min whereas the angiotensin I generated after 120 min was virtually the same as that generated after 60 min thus indicating a possible reversible activation of human prorenin. We speculate that prorenin may be reversibly activated by contact with the lipidic portion of the cell membrane either inside or outside the cells thus allowing a limited angiotensin II-generating cascade at a local site initiated by prorenin independently from the presence of active renin.

Angiotensin I↗
PubMed1989

[Possible activation of human prorenin by contact with the cell membrane].

Semipurified human kidney prorenin was exposed in vitro to a mixture of lipids mimicking the composition of the inner leaflet of the cell membrane, in the presence of semipurified human angiotensinogen at a concentration of 1/4 Km. Prorenin was activated in a time-dependent manner over a period of 60 min. This lipid-dependent activation was completely reversed thereafter. Pre-incubation with anti-renin serum completely prevented this activated prorenin-dependent generation of angiotensin I. Our data suggest that human prorenin can be reversibly activated by contact with the cell membrane.

Angiotensin I↗
PubMed1988

Effects of nitrendipine on blood pressure, renin-angiotensin system, and kidney function in essential hypertension.

The effects of nitrendipine (10 mg b.i.d.) on blood pressure, renin-angiotensin-aldosterone system, and kidney function (by means of glomerular and tubular function) were studied in comparison to captopril (50 mg b.i.d.) and to nitrendipine (10 mg q.d.) + captopril (25 mg b.i.d.) in 30 untreated essential mild-to-moderate hypertensives. The blood pressure lowering effect was similar with either regimen. Nitrendipine showed an acute and chronic natriuretic effect not accompanied by modifications of kidney function. All regimens were well tolerated by the patients without any appreciable side effects over the 4-week study period.

Adult↗
PubMed1984

The brain amino acid pattern in experimental coma due to phenytoin in guinea pigs.

An experimental study was carried out on 50 guinea pigs to evaluate the amino acid pattern in the whole brain after a toxic dose of phenytoin (1 g . kg-1 body wt). One group of 25 guinea pigs was treated with the drug which made them comatose, and their brains removed by craniotomy and frozen in liquid nitrogen; 25 guinea pigs were used as a control group. The brain amino acid pattern was determined by ion-exchange chromatography. All the amino acids, except threonine and methionine, decreased. Hypotheses about the particular cerebral metabolic pathways involved are discussed.

Amino Acids↗
PubMed1984

The amino acid cerebral pool after toxic doses of lidocaine and mexiletine. An experimental study on guinea pigs.

Lidocaine and Mexiletine are two anti-arrhythmic drugs which when administered in toxic doses cause alterations in the central nervous system (convulsions, tremors, coma). An experimental study was carried out to clarify some neurological side-effects caused by these two drugs, by studying the variations of the brain amino acid pool. With Lidocaine one can observe an increase of phenyl-alanine and tyrosine, a decrease of glycine, GABA, alanine, aspartate and glutamate, while taurine and ammonia showed no significant changes. After Mexiletine one can observe an increase of ammonia, a decrease of GABA, glutamine, glycine and alanine, while glutamate, taurine, phenyl-alanine and tyrosine remain within normal values. In conclusion, on the basis of the data obtained by comparing the two drugs, one could say that Lidocaine has a greater interference on the catecholaminic precursors which are little influenced by Mexiletine. For the rest, the data obtained are practically super- imposable .

Amino Acids↗
PubMed1983

The effect of five drugs in coma doses on neurotransmitter amino acids in the brains of guinea pigs.

The study has been carried out in order to investigate the effects of some drugs in coma doses on the concentration in brain of some amino acids involved in brain function. Six groups of 25 guinea pigs each were utilized. In each of the five groups a subcutaneous dose of diazepam, flunitrazepam, phenobarbital, phenytoin or alfaxalone, was injected and one group was utilized as control. Some neurotransmitter amino acids (glutamate, aspartate, glycine and taurine) and precursors of neurotransmitters (phenylalanine and tyrosine) were determined in brain preparations. The results are discussed.

Amino Acids↗