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Biomedical subjects

F Rivera

Publications and source records attributed to F Rivera.

At least 235 records · Page 13Linked to original sources
PubMed1981

Bottled mineral waters polluted by protozoa in Mexico.

A survey of protozoa polluting bottled mineral water in Mexico was carried out using samples obtained form the three best-selling brands of bottled mineral water in the country. The organisms were concentrated through filtration procedures and subsequently cultured in the sterile media. The cultures were observed over four weeks, with identification to the level of genus and species. Most commonly found were the amoebae Naegleria gruberi, Acanthamoeba astronyxis, and Vahlkampfia vahlkampfi (trophic as well as cystic stages) plus one flagellate, Bodomorpha minima. No ciliates were detected. The public health importance of the findings is obvious, since some strains of Naegleria and Acanthamoeba have the potential to cause human disease that may lead to death.

Amoeba↗
PubMed1981

Plasma renin activity and urinary sodium excretion as prognostic indicators in nonazotemic cirrhosis with ascites.

Azotemia is an ominous prognostic sign in cirrhosis with ascites. To investigate whether other renal disturbances are also prognostically significant, we studied the renin-aldosterone system and sodium excretion (UNaV) in 75 patients who had nonazotemic cirrhosis with ascites and related these to survival. On the basis of plasma renin activity patients were classified in two groups. Group I included 34 patients with normal renin activity (1.13 +/- 0.69 ng/mL . h) and Group II, 41 patients with high renin activity (7.46 +/- 3.86 ng/mL . h). The two groups differed significantly (p less than 0.001) in plasma aldosterone, UNaV, and wedged hepatic venous pressure but not in clinical features, liver function, glomerular filtration, and renal plasma flow. Patients of Group I lived significantly longer than those of Group II (the 50% survival rates were 28 months and 6 months, respectively). Survival curves obtained after grouping the patients according to UNaV (higher and lower than 10 meq/d) were almost identical to those obtained according to renin activity. The study results indicate that plasma renin activity and UNaV are of prognostic value in nonazotemic cirrhosis with ascites.

Adult↗
PubMed1981

[Effect of chronic administration of cimetidine on adenohypophysis secretion in children].

In view of the existing disagreement on the hormonal effects of a chronic treatment with cimetidine, we have studied on a sample of 18 children, the possible alterations that might occur. A comparison has been established between basal conditions and a two-month treatment with 500 mg. a day, on levels of GH, PRL, LH, FSH, TSH and cortisol (as an indirect measurement of ACTH). The statistic study has not shown any noticeable difference in the considered period of time, and dose that has been used does not provoke any alteration in adenohypophyseal secretion.

Adrenocorticotropic Hormone↗
PubMed1981

Postsynaptic adrenergic unresponsiveness in hypotensive haemodialysis patients.

In order to ascertain the significance of autonomic dysfunction in hypotensive maintenance haemodialysis patients, plasma norepinephrine (NE) was measured by radioenzymatic assay in 15 nondiabetic uraemic subjects of similar age and time on dialysis, five of them chronically hypotensive and 10 normotensive. Hypotensive patients had: 1) Significantly higher NE levels than their normotensive counterparts, both in basal conditions and after orthostatism and 2) significantly lesser increments in mean arterial blood pressure during a NE infusion than the normotensive group. Rather than implicating a mechanism based on autonomic neuropathy, our results suggest that in haemodialysis patients with chronic hypotension, there is a defect located at the adrenergic postsynaptic level.

Adult↗
PubMed1980

Use of piretanide, a new loop diuretic, in cirrhosis with ascites: relationship between the diuretic response and the plasma aldosterone level.

Twenty patients with cirrhosis and ascites but no renal failure were given piretanide, a new loop diuretic, in order to investigate its efficacy and to relate the diuretic response with the pretreatment plasma aldosterone concentration. Eleven patients responded to piretanide 12 mg/day (equivalent in potency to 80 mg furosemide); there was no response in nine patients. Both groups were similar with regard to liver function, plasma urea, serum creatinine, plasma electrolytes, urine volume, and urine potassium concentration. The basal urinary sodium excretion was significantly higher in those patients who responded (23.6 +/- 5.7 mmol/day vs. 4.3 +/- 1.42 mmol/day; P < 0.01) (M +/- SE). Plasma renin activity (PRA) and plasma aldosterone concentration (PAC) were normal or only slightly increased in patients who responded to piretanide (PRA = 1.22 +/- 0.20 ng/ml/h; PAC = 12.25 +/- 2.20 ng/100 ml) and very high in patients who did not respond (PRA = 8.71 +/- 1.18 ng/ml/h; PAC = 84.6 +/- 16.2 ng/100 ml) (P < 0.001). Patients unresponsive to piretanide 12 mg/day also failed to respond when the dose was increased to 24 mg/day. However, the addition of spironolactone, 150 mg/day, to piretanide was followed in these patients by a marked increase in diuresis and natriuresis. These results strongly suggest that the pre-treatment level of aldosterone is an important factor influencing the response to loop diuretics in patients with non-azotaemic cirrhosis and ascites.

Adult↗
PubMed1979

Nonchromaffin paraganglioma of the duodenum.

A benign nonchromaffin paraganglioma of the duodenum is described and compared with other reported cases. Duodenal location is extremely rare but the morphology, based on the optical microscopic pattern (Zellballen) and the ultrastructural appearance is, comparable with paragangliomas of other sites. The lack of nerve fibres and ganglion cells in this tumour, together with the absence of a positive chromaffin reaction permits us to classify it as a pure nonchromaffin paraganglioma. This finding constitutes indirect evidence of the probable existence of a paraganglion in the duodenal wall, a structure not yet demonstrated in the adult.

Duodenal Neoplasms↗
PubMed1979

Renin, aldosterone and renal haemodynamics in cirrhosis with ascites.

The interrelationships between the renin-angiotensin-aldosterone system, renal haemodynamics and urinary sodium excretion were investigated in fifty-six non-azotaemic cirrhotics with ascites. In twelve additional patients the renal renin secretion rate was also studied. Plasma renin activity and concentration and plasma aldosterone ranged from normal to very high values. There was a significant inverse relationship between plasma aldosterone and the urinary sodium excretion. Plasma aldosterone showed a highly significant direct correlation with plasma renin activity, and plasma renin concentration was closely and directly related to the estimated renin secretion rate. Neither plasma renin activity, plasma renin concnetration nor the estimated renin secretion rate correlated with the renal plasma flow or the glomerular filtration rate. These results suggest that in non-azotaemic cirrhosis with ascites the renin-angiotensin-aldosterone system is an important factor influencing sodium excretion, increased plasma renin and aldosterone concentrations are mainly due to an increased secretion rate, and total renal perfusion is not a major factor influencing renin secretion.

Aldosterone↗
PubMedDate not supplied

Renal kallikrein excretion in cirrhotics with ascites: relationship to renal hemodynamics.

To investigate if the renal kallikrein-kinin system may be involved in the homeostasis of renal perfusion in cirrhosis, urinary kallikrein activity was measured in 11 normal subjects, 31 cirrhotics with ascites and preserved renal plasma flow (548.2 +/- 32.2 ml per min) and glomerular filtration rate (85.8 +/- 3.4 ml per min), and 18 cirrhotics with functional renal failure (renal plasma flow: 229.9 +/- 23.4 ml per min; glomerular filtration rate: 34.9 +/- 3.3 ml per min). Plasma renin activity, plasma norepinephrine concentration and the urinary excretion of prostaglandin E2 were also measured in these subjects. Cirrhotics without renal failure showed a significantly higher renin (4.9 +/- 1.1 ng per ml per hr), norepinephrine (458.2 +/- 50.4 pg per ml), urinary kallikrein (15.4 +/- 1.8 pkat per min) and urinary prostaglandin E2 (0.52 +/- 0.08 ng per min) than did normal subjects (1.08 +/- 0.1 ng per ml per hr, 218.1 +/- 18.2 pg per ml; 8.4 +/- 1.4 pkat per min and 0.24 +/- 0.02 ng per min, respectively). Cirrhotics with renal failure showed a significantly higher renin (16.1 +/- 3.4 ng per ml per hr) and norepinephrine (739.4 +/- 79.2 pg per ml), and a significantly lower urinary kallikrein (5.2 +/- 0.6 pkat per min) and urinary prostaglandin E2 (0.15 +/- 0.02 ng per min) than did normal subjects and cirrhotics without renal failure. Glomerular filtration rate correlated (p less than 0.001) with urinary kallikrein (r = 0.53), urinary prostaglandin E2 (r = 0.55), plasma renin (r = -0.41) and norepinephrine (r = -0.44).(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMedDate not supplied

Temporal relationship between hyperaldosteronism, sodium retention and ascites formation in rats with experimental cirrhosis.

To investigate the role of aldosterone in sodium retention and ascites in cirrhosis, the urinary sodium excretion, sodium balance and urinary excretion of aldosterone-18-glucuronide (UAldV) were serially measured in 11 rats undergoing cirrhosis induction with carbon tetrachloride (CT) and phenobarbital (CT rats) and in 10 control rats which received phenobarbital. All CT rats developed ascites, seven within the ninth week after starting the program and four within the 10th week. One week before the onset of ascites, CT rats and control rats were different with respect to sodium excretion (1.41 +/- 0.15 vs. 1.82 +/- 0.1 mEq per day), sodium balance (0.57 +/- 0.12 vs. 0.20 +/- 0.09 mEq per day) and UAldV (67.8 +/- 9.5 vs. 25.7 +/- 1.7 ng per day). These differences were more pronounced within the week in which ascites was detected in CT rats. Before these 2 weeks, both groups did not differ with respect to these parameters. In the 132 urine samples obtained in CT rats, there was a correlation between sodium excretion and UAldV (r = -0.53; p less than 0.001). Twenty-one additional CT rats were divided into two groups. Eleven animals were given spironolactone (20 mg per day s.c. in olive oil) from the 6th week, and 10 only received olive oil. Thirteen weeks after starting the program, all rats not treated with spironolactone had sodium retention and ascites (in five rats, ascites appeared within the ninth week and in five within the tenth week); this occurred in only one animal treated with spironolactone.(ABSTRACT TRUNCATED AT 250 WORDS)

Aldosterone↗
PubMedDate not supplied

Atrial natriuretic factor in cirrhosis with ascites: plasma levels, cardiac release and splanchnic extraction.

The aim of this study was to determine the plasma levels, cardiac release and splanchnic extraction of atrial natriuretic factor in cirrhosis with ascites. The plasma concentration of immunoreactive atrial natriuretic factor in samples obtained from an antecubital vein was measured in 18 healthy volunteers and in 35 cirrhotics with ascites. In 11 of these cirrhotics and in 11 patients admitted to the hospital for the study of a thoracic pain who had no clinical or hemodynamic signs of cardiac failure (control group), the plasma levels of immunoreactive atrial natriuretic factor in samples from the coronary sinus, right atrium, pulmonary artery, hepatic vein and femoral vein were determined and the coronary sinus blood flow measured by thermodilution. Cirrhotic patients showed significantly higher plasma levels of immunoreactive atrial natriuretic factor in each vascular territory studied than did control subjects (coronary sinus: 101.2 +/- 10.6 vs. 26.1 +/- 4.7 fmoles per ml; right atrium: 32.5 +/- 5.8 vs. 9.4 +/- 3.5; pulmonary artery: 36.8 +/- 10.1 vs. 7.5 +/- 2.4; hepatic vein: 10.7 +/- 2.0 vs. 2.7 +/- 0.8; femoral vein: 18.2 +/- 2.4 vs. 3.1 +/- 0.9; antecubital vein: 14.7 +/- 1.6 vs. 4.0 +/- 0.8). The coronary sinus blood flow was also higher in cirrhotics (200 + 22 ml per min) than in controls (105 +/- 7 ml per min). Consequently, the estimated cardiac release and cardiac production of immunoreactive atrial natriuretic factor were strikingly increased in cirrhotics (13,334 +/- 2,007 and 5,484 +/- 1,734 fmoles per min, respectively) as compared to control subjects (1,669 +/- 338 and 1,431 +/- 350 fmoles per min, respectively; p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Ascites↗