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Biomedical subjects

B Miranda

Publications and source records attributed to B Miranda.

At least 73 records · Page 4Linked to original sources
PubMed1993

Peritoneal resting is beneficial in peritoneal hyperpermeability and ultrafiltration failure.

Ultrafiltration failure (UFF) is one of the most frequent causes of continuous ambulatory peritoneal dialysis (CAPD) dropout and is a common consequence of peritoneal hyperpermeability secondary to inappropriate regeneration of mesothelial cells. In this paper we present the results of 25 peritoneal resting periods of 4 weeks in 16 patients who showed UFF. The mean duration of CAPD was 44 +/- 22 months. All patients had been free of peritonitis for at least 3 months when included in the peritoneal resting trial. UFF was always defined as a long-lasting decrease of UF capacity such that dry weight could no longer be achieved by CAPD. The former incidence of peritonitis was 3.9 +/- 2.3 episodes. Results compared to the preresting data: urea MTC (mass transfer coefficient) decreased from 24.9 +/- 6.8 to 21.0 +/- 6.1 (p < 0.05), creatinine MTC from 16.5 +/- 6.0 to 13.8 +/- 4.0 (p < 0.05), and UF increased from 493.8 +/- 278.0 to 881.3 +/- 388.1 (p < 0.001). The response in terms of UF in patients with low permeability ultrafiltration (creat MTC less than 13) was heterogeneous and lower than in patients with criteria of hyperpermeability (greater than 13): 720 +/- 396 to 1150 +/- 533 (NS) versus 491 +/- 310 to 808 +/- 205, respectively. Simultaneously, creatinine MTC did not change in the former group (10.2), while hyperpermeability patients showed a remarkable decrease (19 +/- 5 to 15 +/- 2, p < 0.05). In conclusion, peritoneal resting is a useful tool in the management of ultrafiltration failure in CAPD patients, primarily in those with peritoneal hyperpermeability.

Adult↗
PubMed1993

The pharmacokinetics of a single dose of calcitriol administered subcutaneously in continuous ambulatory peritoneal dialysis patients.

OBJECTIVES: To evaluate the kinetics of calcitriol (1,25(OH)2D3) administered subcutaneously. STUDY DESIGN: Calcitriol kinetics and efficacy after subcutaneous administration were studied in 13 CAPD patients with varying degrees of increased plasma levels of parathyroid hormone (i-PTH). A single dose of 2 micrograms of calcitriol was administered subcutaneously, and its serum levels at baseline and after 1, 2, 6, 12, and 24 hours were determined. Plasma ionized calcium and i-PTH were also determined at these periods. RESULTS: Serum calcitriol levels reached peak levels of 60 and 70 pg/mL at 1 and 2 hours after administration, respectively. These levels decreased thereafter, but remained above baseline values during 24 hours. The mean value of the area under the curve (AUC) was 809 +/- 226 pg/mL/hour. Plasma i-PTH levels showed a slight decrease after 1 and 2 hours, returning to baseline levels after this period. Plasma ionized calcium did not show significant changes during the study. A slight pain at the site of injection was mentioned by some patients. CONCLUSIONS: The subcutaneous route for calcitriol administration achieves theoretically adequate plasma levels in continuous ambulatory peritoneal dialysis (CAPD) patients. This is important when parenteral administration of calcitriol is considered in the treatment of secondary hyperparathyroidism.

Adult↗
PubMed1992

Prevalence of hepatitis C antibodies (HCV) in a dialysis population at one center.

Hepatitis C (HC) has been recently diagnosed by determination of specific antibodies that represent the former so-called non-A, non-B hepatitis. We studied the prevalence of plasma HCV antibodies among 61 unselected patients on hemodialysis (HD) and 43 on continuous ambulatory peritoneal dialysis (CAPD). Plasma C-antibodies were determined through the ELISA test system. Transfusion policy was the same in both groups. The prevalence of hepatitis C virus antibodies was significantly higher in hemodialysis patients than among those on CAPD. Time on dialysis, previous blood transfusions, and renal transplantation seem to increase the prevalence of C hepatitis antibodies among hemodialysis patients. The effect of these parameters on CAPD was smaller. Understanding the reasons for these differences may help prevent this disease among dialysis patients.

Blood Transfusion↗
PubMed1991

Characterisation of the mitogenic-induced capacity of peritoneal effluent on human and mice fibroblasts in culture.

During continuous ambulatory peritoneal dialysis, solutes capable of stimulating fibroblast activity could be transferred into dialysate; their significance and consequences remain to be established. Sixty-three stable non-selected patients on CAPD were included in this study. Peritoneal transport for water and small solutes was assessed. To explore the mitogenic-induced capacity of peritoneal nocturnal effluent, 50 microliters were added to culture plates of mice and human fibroblasts. Peritoneal effluent alone shows a mitogenic potency slightly greater than insulin and clearly less than bovine fetal serum. When coadjuvants are added, mitogenicity increases but in a variable manner among patients. No differences can be observed in relation to diabetes mellitus, time on CAPD, previous peritonitis, and losses of diffusion capacity. We noted significant inverse linear correlations between mitogenicity value and ultrafiltration, effluent calcium, and creatinine. Neither adrenergic nor calcium-channel blockers influenced these values. We conclude that the peritoneal effluent of CAPD patients has a variable effect on fibroblast growth. Some of the blood components seem to be implicated in this activity. Reduced peritoneal ultrafiltration capacity, probably by a concentration mechanism, is related to a greater mitogenic potency in peritoneal effluent. CAPD patients with impaired ultrafiltration may be at high risk for autoactivation of peritoneal fibroblasts, mainly in mesothelial denudate states.

Adult↗
PubMed1991

Medium term response to H-R erythropoietin in CAPD patients: the influence of erythropoietin plasmatic levels and the effects on peritoneal transport capacity.

Anemia of CRF has been corrected by use of H-R-EPO both in hemodialysis and CAPD patients. Long term response to subcutaneous EPO and its relationship with serum EPO levels remain to be established. Twenty-five CAPD patients treated with CAPD during 30 +/- 28 (mean +/- SD) months were included in this study. The follow-up period was 6-24 months. All patients have been on CAPD at least 6 months and their Hemoglobin (Hb) level was lower than 8.5 g/dl. Twelve patients received EPO by subcutaneous route, at doses of 20 u./Kg daily and 13 other patients at doses of 2000 units twice a week. Thereafter, these doses were adjusted to obtain a Hemoglobin level ranging 10.5-13 g/dl. In conclusion, our results suggest that the subcutaneous route for H-R-Erythropoietin can be considered as the best choice for CAPD patients. Low doses twice a week seem to improve anemia in 2 months. Later, dose adjustment should be done according to the patient's response. The improvement in nutritional status we observed suggests a new positive aspect for EPO therapy. Our data did not show changes in peritoneal function.

Adult↗
PubMed1990

Secondary hyperparathyroidism in CAPD patients: its suppressibility with high doses of calcitriol.

Secondary hyperparathyroidism (HP) is well known complication of long-term uremia. CAPD patients show a peculiar behaviour due to loss of vitamin D metabolites through peritoneum. Severe degrees of hyperparathyroidism may require parathyroidectomy in order to achieve appropriate control. Recently, the possibility of controlling this situation with high oral doses of calcitriol has been communicated. The purpose of this study is to evaluate the effect of this agent on hyperparathyroidism in CAPD patients. Two different groups were constituted according to the length of time on dialysis when HP was detected. All of the patients had i-PTH serum levels five times higher than the normal values (50 pg/ml). During a six month period the daily dose of oral calcitriol was increased in order to achieve a reduction in i-PTH level. The results after this period showed a significant reduction in i-PTH levels (614 +/- 378 to 241 +/- 80 pg/ml) with an average increase in oral calcitriol from 0.16 +/- 0.1 to 0.67 +/- 0.4 with no significant changes in serum calcium or phosphorus. The group with HP at start of dialysis achieved these effects easier and with lower doses of calcitriol. We conclude that moderately high doses of oral calcitriol control secondary hyperparathyroidism in CAPD patients without hypercalcemia.

Calcitriol↗
PubMed1990

Measurement of the peritoneal platelet activity through the effluent betathromboglobulin levels in CAPD patients.

Platelet activity is closely related to endothelium and could release factors able to influence capillary wall and surrounding tissues. BTG is a protein included in platelet vesicles and a measure of its activation. Some alterations of peritoneum could be partially related to platelet activity. BTG peritoneal transport from blood is weight limited (36000) and consequently, high levels in effluent should represent local production. The aim of this study has been to characterize peritoneal effluent BTG.12 patients, on CAPD 27 +/- 15 mon., 5 diabetics were studied. Previous peritonitis was 0.3 +/- 0.4 e/year. Determinations performed: Plasma (P) (BTG, T. protein, albumin, platelet count, Hcto and Fibrinogen) and Effluent (EF) (BTG, T. protein, Fibrinopeptide A, FDP, Fibrinolytic act., Fibrinogen, Plasminogen and Mitogenic induced capacity on Swiss 3T3 mice fibroblasts). To evaluate peritoneal function we used mass transfer coefficients (MTC) and net UF.R.:BTG levels: P 118 +/- 14 EF 34 +/- 14 ng/ml P/EF (%) 31 +/- 13 (6-54%). Regression analysis: P BTG did not show significant relationship with any of the studied parameters. EF BTG showed direct significant correlation (p less than 0.05) with Creatinine-MTC (r: 0.81) and EF Fibrinogen (0.68) and in the limit of significance with EF T. prot (0.57) and EF Mitogenicity (0.62). P/EF BTF showed significant correlation with creatinine-MTC (0.77). The analysis of these values grouping patients showed: diabetes has no influence on BTG values, hypertensive patients show higher P/EF BTG values than normotensive (39 +/- 9 vs 23 +/- 11%, p less than 0.05) and no influences of peritonitis or CAPD period were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological Transport↗
PubMed1990

Treatment of the anemia with human recombinant erythropoietin in CAPD patients.

Three homogenous groups of CAPD patients, all of them with plasma hemoglobin levels lower than 8 g/dl were studied. Group 1 included 8 patients who received EPO by the subcutaneous route (s.c), at doses of 20 u./kg daily; this dose was reduced when a hemoglobin level higher than 10.5 g/dl was reached. Group 2 included 7 patients treated with EPO by subcutaneous route but at doses of 2000 units twice a week. Group 3 was constituted by 4 patients receiving EPO by intraperitoneal route (i.p.), at doses of 4000 u/day, three days a week. All patients showed an increase in hematocrit and Hb levels after three months of treatment, but the mean EPO dose was quite different comparing the groups, maintaining the reached levels at the 9th month; reticulocyte count increased only during the first month. The rest of clinical and biochemical parameters did not suffer any significant modifications. Our features showed a higher profit, that is, higher increase in Hb level with lower dose of EPO in the s.c. group in respect to i.p. group. Furthermore, we have registered a marked increase in the frequency of exogenous peritonitis in these particular patients while using i.p. EPO. In conclusion, we feel that subcutaneous route for H-R-Erythropoietin is an ideal way for this treatment, resulting in a more adequate profit ratio than that described in hemodialysis patients. The intraperitoneal route is more expensive and risky for the peritoneum, probably as a consequence of the increase of manipulations.

Adult↗
PubMed1989

[Treatment of arterial hypertension in the aged].

The response to different therapeutic schedules in arterial hypertension in the elderly is studied and compared with response to treatment in younger patients. Blood pressure in the elderly was best controlled with non pharmacologic measures and low doses of diuretics; there were no differences between both groups with respect to complications and side effects. The response to angiotensin-converting enzyme inhibitors is also evaluated, presenting good results on blood pressure control without side effects in the elderly, although efficaciousness was higher in younger patients. The possible therapeutic schedules in arterial hypertension in the aged are discussed.

Age Factors↗
PubMed1989

Converting enzyme inhibition in chronic renal failure.

Ten patients with chronic renal failure whose hypertension was controlled with triple drug therapy consisting of propranolol-hydralazine-furosemide were switched to the angiotensin-converting enzyme (ACE) inhibitor captopril for a period of 12 months. Control of hypertension was similar with both antihypertensive regimens. Clearance of inulin and of paraaminohippuric acid increased during the first 3 months of captopril therapy and remained stable thereafter. Moreover, the decline in the reciprocal of serum creatinine over time observed during triple drug therapy was arrested during therapy with the ACE inhibitor. If the salutary effects of captopril are sustained, the results obtained in the current studies would suggest that control of hypertension by ACE inhibition may be effective in slowing progression of renal failure. Future studies to answer this important question are necessary.

Adult↗
PubMed1989

Effects of nisoldipine on renal function in normal volunteers and essential hypertensive patients.

To evaluate the renal effects of nisoldipine (N), a dihydropyridine derivative, we have evaluated the variations of blood pressure (BP), heart rate, glomerular filtration rate (GFR), renal plasma flow (RPF), 24-h natriuresis, and renal capacity to excrete an i.v. sodium load (2,000 ml isotonic saline in 4-h) in response to a 4-day course of therapy with placebo (P) and N in six normotensive volunteers and six mild-to-moderate essential hypertensive patients. Both volunteers and patients were studied on two constant diets (20 and 150 mEq of sodium daily). No parameters changed after P. On the contrary, N induced a significant fall of BP (p less than 0.01) in the group of patients but not in volunteers. In both groups RPF and GFR increased significantly (p less than 0.05-0.01) while on a low sodium intake but remained constant when sodium intake was high. In the two groups studied, nisoldipine exhibited natriuretic properties manifested by an increase in the 24-h output of sodium as well as by an increased renal capacity to excrete the i.v. sodium load. These natriuretic properties were present in both situations of sodium load and could be facilitated by the change in renal hemodynamics observed when the intake of sodium was low.

Adult↗
PubMed1989

Comparative study of two different routes for insulin administration in CAPD diabetic patients. A multicenter study.

CAPD has been considered an appropriate method for treatment of diabetics in renal failure. Up to now the choice of route for insulin administration in these patients has not been definitely defined, although there is a general consensus for employing the intraperitoneal route for this purpose. However, contradictory data have appeared on this subject. Our aim has been to investigate whether the subcutaneous or intraperitoneal route makes any difference to metabolic control, and if so what is the price in terms of the incidence of peritonitis. Two groups of diabetic patients from three different hospitals with a similar peritonitis incidence and training protocols were studied. Of the 30 patients, 15 were treated with subcutaneous insulin (sc group) and in the other 15 the intraperitoneal route was employed (ip. group). The average follow-up period was 20.8 +/- 7.5 months for sc group and 18.7 +/- 8 months for ip. group. Insulin requirements were 30 +/- 11 u./day in the sc. and 110 +/- 60 u/day in the i.p. group (p less than 0.05) and remained constant during the study period. Metabolic controls (home glucose levels, HbA1C, hospital fasting glucose levels) were similar for both groups. However, the incidence of peritonitis was 4 times greater in the ip. group. In the ip. group 18 peritonitis episodes were registered in 280 patient-months vs 5 episodes in sc. group in 312 patient-months. We conclude that the intraperitoneal route for insulin administration in diabetic CAPD patients produces a higher risk of suffering peritonitis with no real metabolic improvement in the medium term.

Blood Glucose↗
PubMed1989

Induced changes of the peritoneal diffusion capacity by smoking, intraabdominal hypertension and omentectomy.

UNLABELLED: Peritoneal membrane suffers in some CAPD patients changes which modify its functionalism. In order to know whether these changes could be expected or appropriate, it is necessary to explore the general and particular conditions which can alter peritoneal physiology. Three aspects, smoking, intraabdominal hyperpressure and and omentectomy are situations which have not been included in the studies of peritoneal physiology. PATIENTS: The control group was constituted by 23 patients. Diabetics were studied as a separate group, with their own 10 patient controls. Smokers (1-20 cigarettes per day): 15 were non-diabetic patients, 9 were females. Diabetic smokers: 7 patients. Intraabdominal hyperpressure was determined by two big polycycstic kidneys (PCKD) in 8 patients, none diabetic. Omentectomy was performed in 6 non-diabetic and 9 diabetic patients. In all cases the procedure was prescribed because of an early catheter entrapment. Smoker patients show significant higher MTCs values for urea and creatinine than controls, but the slightly lower ultrafiltration value did not reached significant difference. Polycystic kidney patients showed lower MTCs values in respect to controls. Ultrafiltration capacity was similar. Omentectomized patients did not show any differences in respect to controls. In the diabetic patients group, neither ultrafiltration nor MTCs values presented significant differences between the established subgroups. So, smoking did not seem to induce higher MTC values as in the non-diabetic group. In conclusion, and according to the present results, two more situations should be taken into account in the evaluation of the peritoneal membrane dialyzing capacities: smoking, which increases diffusion capacity except for diabetics and PCKD with tow big kidneys, which decreases this capacity.(ABSTRACT TRUNCATED AT 250 WORDS)

Abdomen↗
PubMed1989

[Clinical characteristics of arterial hypertension in the elderly].

The clinical characteristics of systolic and diastolic hypertension in 75 and of systolic hypertension in 50 elderly patients have been studied and the results have been compared to those obtained in 23 normotense elderly controls and 500 young patients with essential hypertension. A greater incidence in cardiovascular and neurologic morbility was observed in the hypertense elderly, existing also a greater incidence of electrocardiographic abnormalities and impairment in renal function. The changes in blood pressure with postural changes and isometric and physical exercise were evaluated in a subgroup of these patients, finding that the elderly with hypertension, specially those with systolic hypertension, showed orthostatic hypotension, and an increase in blood pressure with exercise, reaching levels that could potentially cause the clinical complications.

Aged↗