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Biomedical subjects

F Rivera

Publications and source records attributed to F Rivera.

At least 217 records · Page 12Linked to original sources
PubMed1984

Effect of demeclocycline on renal function and urinary prostaglandin E2 and kallikrein in hyponatremic cirrhotics.

8 cirrhotics with hyponatremia were given demeclocycline (DMC) 900 mg/day to investigate its effect on renal function, plasma renin activity, aldosterone and urinary excretion of prostaglandin E2 and kallikrein. In 7 patients DMC induced an increase of free water clearance (from -0.36 +/- 0.06 to 0.13 +/- 0.06 ml/min) and serum sodium concentration (from 125.4 +/- 0.09 to 131.1 +/- 1.0 mEq/l, mmol/l). In 5 of these patients DMC also induced a marked reduction of glomerular filtration rate (from 72.2 +/- 6.2 to 31,2 +/- 4.7 ml/min) and renal plasma flow (from 468 +/- 98 to 195 +/- 55 ml/min) which could not be explained on the basis of hypovolemia. In each case this renal impairment was not associated with changes in urinary concentration of beta 2-microglobulin, urinary casts excretion, fresh urine sediment or urine protein content and disappeared after discontinuation of the drug. DMC induced a marked increase in the urinary excretion of prostaglandin E2 (from 0.82 +/- 0.27 to 6.16 +/- 1.91 ng/min) in 6 out of the 7 patients who responded to DMC and a marked reduction in urinary kallikrein (from 16.1 +/- 4.4 to 4.2 +/- 1.6 pkat/min) in the 5 patients who developed renal insufficiency. The serum DMC concentration was greater than 5 micrograms/ml in all patients who responded to DMC, greater than 8 micrograms/ml in all cases who developed renal insufficiency and of 3 micrograms/ml in the case not responding to DMC. (ABSTRACT TRUNCATED AT 250 WORDS)

Acute Kidney Injury↗
PubMed1984

The role of IgA and IgG immune complexes in IgA nephropathy.

The presence of circulating immune complexes in 54 patients with IgA nephropathy has been studied by two different techniques. 64% of the patients had IgG immune complexes and 37% had IgA immune complexes, both determined with the Raji cell assay, and 48% of patients had IgA immune complexes with the anti-IgA inhibition binding assay (anti-IgA Inh BA). In sequential sera from individual patients, immune complexes remained persistently positive or negative in more than 50% of the cases being intermittently in the rest. The immune complexes detected by the Raji cell assay were mostly of 7-13S in size, while those detected by anti-IgA Inh BA were bigger. There was a good correlation between the serum levels of polymeric IgA and the presence of IgA complexes (Raji cell assay). A certain correlation (p less than 0.05) was found between these IgA immune complexes and the clinical activity assessed by the hematuria. A similar correlation (p less than 0.05) was found with specific polymeric IgA immune complexes studied by a method recently described. No relationship was observed between the presence of any HLA antigens and the existence of circulating immune complexes. These results support the contention that IgA immune complexes, especially those composed of polymeric IgA, may have a role in the pathogenesis of IgA nephropathy. Moreover, the high serum levels of polymeric IgA observed in these patients could contribute to the slow clearance and long persistence in the circulation of IgA immune complexes with their subsequent deposition at the glomerular mesangium.

Adolescent↗
PubMed1984

Phenytoin in IgA nephropathy: a long-term controlled trial.

The final report of a long-term nonrandomized controlled trial of phenytoin therapy in patients with IgA nephropathy is presented. The mean time period of follow-up was 17 months (range 6-48) in the treated group (41 patients) and 14 months (range 6-36) in the nontreated group (32 patients). Both groups were comparable in age, sex, onset of the nephropathy, blood pressure and renal function. The number of episodes per year of macroscopic hematuria decreased in both groups, but was significantly lower at each time period in the treated group than in the control one. The diminution of microhematuria only occurred in the treated group. 1 patient in each group developed advanced renal failure. The mean serum IgA concentration diminished significantly in the treated group, as early as 6 months, but not in the nontreated group. There was a certain association between the presence of the HLAA2 and BW 35 antigens and the lowering of serum IgA. A normalization of the high serum levels of polymeric IgA occurred in the treated patients. A marked diminution of the Raji IgA immune complexes, well correlated with hematuria, was only observed in the treated group. However, despite the diminution of the serum IgA levels, the disappearance of the potential pathogenic IgA immune complexes and the hematuria in a number of treated patients, a progression in the percentage of global or focal glomerular sclerosis and/or vasculointerstitial lesions was seen in some of them. It is concluded that phenytoin decreases the clinical activity and corrects some of the immunological alterations of a certain number of patients with IgA nephropathy but has no valuable effects on the renal lesions. The overall results of this trial do not suggest the employment of this drug in patients with IgA nephropathy and normal renal function. Our data also suggest that a nonimmunological mechanism may be of importance in the progression of chronic renal damage in this disease.

Adolescent↗
PubMed1984

Hepatic and kidney uptake of soluble monomeric and polymeric IgA aggregates.

To investigate the handling of IgA by the mononuclear phagocytic system and by hepatocytes of mice, soluble, similar sized, heat-aggregated monomeric (A-mIgA) and polymeric IgA (ApIgA) were used as akin to IgA immune complexes. The half-life of the clearance from circulation decreased from 2.5 hr to 4.2 min and from 22 min to 1.8 min after aggregation of mIgA and pIgA, respectively. Tissue localization experiments indicated that the liver was the organ predominantly involved in the uptake and catabolism of the proteins injected. The rate of the liver catabolism and/or elimination of aggregated polymeric IgA was the slowest up to 24 hr of injection. Aggregated pIgA was deposited in the kidney in larger amounts than aggregated mIgA. The participation of hepatocytes and nonparenchymal liver cells was determined after isolation and purification of these cells. The four substances injected, pIgA, A-pIgA, mIgA and A-mIgA, were predominantly localized in nonparenchymal cells when the uptake was expressed per volume of cells, due to their lower protein content. However, when the results were expressed cell to cell there was a high ratio of IgA aggregates associated with hepatocytes to nonparenchymal cells. It seems probable, therefore, that hepatocytes are almost exclusively responsible for clearance of IgA aggregates from blood.

Animals↗
PubMed1983

A survey of pathogenic and free-living amoebae inhabiting swimming pool water in Mexico City.

A survey of pathogenic and free-living amoebae in swimming pool waters of Mexico City was performed. Among the organisms isolated those which have public health importance were Naegleria fowleri Carter and Acanthamoeba castellanii Douglas. Amoebae of the genera Acanthamoeba, Naegleria, and Vahlkampfia were recovered in their cystic stage while those specimens of the genera Amoeba, Entamoeba, Thecamoeba, and Vanella were recovered only in their trophic stage during this study. Amoebae were concentrated through filtration procedures and subsequently cultured in different culture media. Nonpathogenic amoebae also isolated by culture included: Amoeba proteus (Pallas) Leidy, Amoeba striata Penard, Paratetramitus jugosus Page, Acanthamoeba astronyxis Ray and Hayes, Vahlkampfia avara Page, Vahlkampfia inornata Page, Thecamoeba verrucosa Ehrenberg, and Vanella mira Schaeffer. Trophozoites of Entamoeba gingivalis Gros, were also recovered, both directly and by culture. Most commonly found were amoebae of the species Naegleria gruberi Schardinger (59.02%), N. fowleri (16.77%), and A. castellanii (7.64%). Least-frequently found amoebae belonged to the species Thecamoeba verrucosa (0.12%). All isolated strains of N. fowleri and A. castellanii were thermophilic at 45 and 40 degrees C, respectively, and also pathogenic when inoculated into white mice. More populated by amoebae were those swimming pools of the indoor type with an inner side garden. It was also shown that the free residual chloride values of 0.50 to 1.5 mg/liter, ordinarily used in pool waters, are not adequate for elimination of amoebae.

Amoeba↗
PubMed1983

Reduced hepatic insulin extraction in obesity: relationship with plasma insulin levels.

To elucidate if there are alterations in insulin metabolic clearance in obesity under basal conditions, plasma insulin and C-peptide were measured in 22 obese patients and 8 normal subjects, and the plasma C-peptide to insulin molar ratio was used as an index of hepatic insulin extraction. In obese patients, the C-peptide to insulin molar ratio correlated indirectly with basal plasma insulin levels (r = 0.71; P less than 0.001), being low in the obese patients with higher insulin levels and within the normal range in obese patients in which insulin levels were similar to those of control subjects. It is suggested that hepatic insulin extraction is decreased in obesity, even under basal conditions, but this alteration is only manifested when plasma insulin levels are high.

Adult↗
PubMed1983

Randomized comparative study of efficacy of furosemide versus spironolactone in nonazotemic cirrhosis with ascites. Relationship between the diuretic response and the activity of the renin-aldosterone system.

Loop and distal diuretics are the basic drugs for the treatment of ascites. Although pharmacologic studies indicate that the natriuretic potency of loop diuretics is much greater than that of distal diuretics, there are no studies comparing the efficacy of these drugs in cirrhosis. Forty nonazotemic cirrhotic patients with ascites and avid sodium retention were randomly allocated into two groups. Group 1 contained 21 patients treated with furosemide; group 2 contained 19 patients treated with spironolactone. The initial doses were 80 and 150 mg/day, respectively. These doses were increased to 160 and 300 mg/day, respectively, if there was no response. Cases not responding to furosemide and spironolactone were later treated with spironolactone and furosemide, respectively. In group 1, 11 of the 21 patients responded to furosemide, while in group 2, 18 of the 19 patients responded to spironolactone (p less than 0.01). Of the 10 patients in group 1 not responding to furosemide, 9 responded later to spironolactone. The diuretic response to furosemide and spironolactone was related to the activity of the renin-aldosterone system. Patients with higher renin and aldosterone did not respond to furosemide and required 300 mg/day of spironolactone to achieve a diuretic response. These results indicate that (a) at the dosages used in the study, spironolactone is more effective than furosemide in nonazotemic cirrhosis with ascites, and (b) the activity of the renin-aldosterone system influences the diuretic response to furosemide and spironolactone in these patients.

Ascites↗
PubMed1983

[Effect of carbamate pesticides on the induction of hepatic enzymes of the rat and on the microsomal phospholipid changes].

The influence of two carbamine pesticides i.e., manebe and carbaryl upon the hepatic microsomal enzymes induction in the rat was studied. Both substances, when administered by themselves, affect only slightly liver weight, P 450 cytochrome rates and bilirubin glucuronosyltransferase, in the microsome fraction of the hepatic homogenate. It seems, however, that carbaryl is involved in producing a slight induction, whereas manebe acts inversely. Yet, manebe changes largely the induction effects of phenobarbital when associated with the latter. In the animal treated simultaneously with manebe and phenobarbital, the increase in the rate of hepatic microsomal P 450 cytochrome as well as the variations in the distribution of fatty acids in phospholipids, are significantly lower than in the animal solely treated with phenobarbital.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1983

Immune complexes in IgA nephropathy: presence of antibodies against diet antigens and delayed clearance of specific polymeric IgA immune complexes.

Several features suggest that IgA nephropathy is an immune complex (IC)-mediated disease. The source of antigen(s) is unknown but the predominant involvement of IgA suggest that it is associated in some way with the gut or respiratory tract. Taking into account the specific hepatobiliary transport by polymeric IgA of circulating antigens entering through the mucosal surfaces we examined the possible involvement of antibodies against food antigens in the circulating IC and the existence of a defect in their blood clearance in patients with IgA nephropathy. A rise in multimeric IgA-IC (Raji assay) occurred in three of seven control subjects with a peak at 2-4 h after food ingestion. The amount of multimeric IgA-IC present at fasting in four out of six patients, diminished 2-4 h after food challenge, reaching a new peak around 6 h. At fasting, three out of six patients had IC containing antibodies against diet antigens (e.g. ovalbumin). These IC paralleled, both in patients and controls, the levels of multimeric IgA-IC. In patients small multimeric IgA-IC predominated at fasting and 24 h after food ingestion, while larger IC were detected at 2-4 h of food challenge. The specific polymeric IgA-IC showed in controls a maximal peak with similar distribution to that of multimeric IgA-IC, but with a quicker disappearance from the circulation. By contrast, polymeric IgA-IC remained elevated 24 h after food ingestion in most patients. These results suggest that antibodies against common antigens are within circulating IC and that a defect in the hepatic clearance of circulating polymeric IgA-IC exists in patients with IgA nephropathy.

Antibodies↗
PubMed1983

Delayed clearance of specific polymeric IgA immune complexes in patients with IgA nephropathy.

The presence of multimeric (polymeric and monomeric) IgA immune complexes (IC), detected by Raji cell assay and by the inhibition binding assay, as well as the specific polymeric IgA-IC were examined before and after the ingestion of 100 g protein. A rise in multimeric IgA-IC occurred in three out of seven controls with a peak at two to four hours after the meal, being cleared thereafter. The amount of multimeric IC present at fasting in four of six patients diminished at two to four hours after food challenge reaching a new peak around six hours. In both controls and patients, IC containing antibodies against diet antigens (e.g. ovalbumin) paralleled those of multimeric IgA-IC. In controls the specific polymeric IgA-IC presented a maximal peak with distribution similar to multimeric IgA-IC, but with a faster disappearance from the circulation. By contrast, polymeric IgA-IC remained elevated 24 hours after food ingestion in most patients. These results suggest that a defect in the hepatic clearance of circulating polymeric IgA-IC exists in patients with IgA nephropathy.

Adult↗
PubMed1982

Luteal phase in infertility: problems of evaluation.

This study was undertaken to examine the endometrial data in 200 infertile women whose three progesterone estimations per cycle totaled over 15 ng/ml when taken from 11 to 4 days preceding menstruation. Forty-three patients (21.5%) showed defective endometria in two separate cycles. No difference was found when plasma progesterone concentrations in this group were compared with those of the remaining 157 infertile patients with normal endometria. Further, plasma progesterone in infertile women (both groups) was similar to a control group of 12 fertile women with normal secretory endometria. Endometrial biopsy is essential in the evaluation of luteal function in infertility and cannot be totally replaced by the use of plasma progesterone in three samples during the luteal phase since it failed to detect as much as 21.5% of abnormal secretory phases.

Adult↗
PubMed1982

Handling of soluble IgA aggregates by the mononuclear phagocytic system in mice. A comparison with IgG aggregates.

We have studied the fate of soluble stable aggregates of human IgA (A-IgA) and IgG (A-IgG) after their injections in mice, as well as in vitro catabolism by liver, kidney and peritoneal macrophages. The half-life of the fast component of blood clearance was similar for both aggregates. However the half-life of the slow component of A-IgA clearance was significantly slower than A-IgG (t1/2 10 . 03 v. 7 . 52 hr, respectively). The A-IgA deposited in liver and kidney was removed significantly more slowly than A-IgG. Studies in isolated liver and kidney slices suggest that this could be due to the impaired catabolism of A-IgA as opposed to that of A-IgG. Interestingly the kidney hardly participates in the processing of A-IgA. At the three doses employed (1, 5 and 10 micrograms of both aggregates) peritoneal macrophages bound and catabolised significantly less amount of A-IgA than A-IgG. Complement seems to have no role in the processing of A-IgA by peritoneal macrophages unlike that observed with A-IgG. It is suggested that the impairment in handling of A-IgA by the mononuclear phagocytic system could provoke their persistence in the circulation and deposition at sites susceptible to injury. These results may be of some relevance for the understanding of physiological IgA-IC (immune complex) clearance and for the pathogenesis of IgA-related diseases.

Animals↗
PubMed1981

Oat cell carcinoma of the oesophagus. Case description and review of the literature.

The small oat cell type of carcinoma is only rarely seen in extrapulmonary sites. To date, nineteen cases have been described in the oesophagus, almost all by Japanese authors. In this report we review the relevant literature and add one more case of pure type to the total. The histopathological, histochemical and ultrastructural findings and the similarity of this tumour to the oat cell bronchial carcinoma, lead one to propose that it originates in the cells of the APUD series, which have been demonstrated in the normal oesophageal epithelium. Thus is represents on endocrine carcinoma of the oesophagus.

APUD Cells↗