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Biomedical subjects

F del Greco

Publications and source records attributed to F del Greco.

At least 19 recordsLinked to original sources
PubMed1992

Response to head-up tilt in cramping and noncramping hemodialysis patients.

Hemodialysis-associated skeletal muscle cramps are generally ascribed to a reduction in plasma volume, but during this procedure, it is not known how volume contraction results in cramps. To elucidate this mechanism, we compared responses to one hour of 60 degrees head-up tilt in 8 patients who cramped during no more than one-sixth of their dialyses and in 8 patients who cramped at least half the time. Age and recumbent blood pressure were similar in each group, but more patients with frequent cramps had diabetes underlying their renal failure (p = 0.013) and had been dialyzed for less than 3 years (p = 0.020). Baseline plasma renin activity and plasma norepinephrine and arginine vasopressin concentrations were similar in both groups, except plasma renin activity in one patient with frequent cramps, which was 15 times higher than in the other patients. After tilting, systolic blood pressure fell an average of 17% in patients who cramped infrequently (p = 0.0031) but only 10% in frequently cramping patients. The ratio of tilt/recumbent norepinephrine levels exceeded 1.5 in 7 patients with frequent cramps but was less than this in 6 patients who cramped infrequently (p = 0.020). One of the 2 infrequently cramping patients with a ratio above 1.5 was the only individual to have a normal renin response to tilt. We propose that cramps are prone to occur during hemodialysis in patients whose sympathetic nervous system response to volume stress is partially intact but is not modulated by concurrent activation of the renin-angiotensin system.

Adult↗
PubMed1990

Activation of renin-angiotensin system does not cause skeletal muscle cramps during hemodialysis.

Activation of the renin-angiotensin system usually occurs during hemodialysis and in hemodialyzed normal dogs parallels reductions in blood flow to a tissue group that is largely composed of skeletal muscle. To determine if excessive activation of this system might cause dialysis-associated skeletal muscle cramps in some patients, we conducted a double-blind, randomized and balanced trial in which 5 patients with frequent dialysis-associated cramps were each given either a 25 mg oral dose of captopril or placebo 1 h before 8 consecutive dialyses. Captopril increased the frequency of dialyses complicated by skeletal muscle cramps in 1 patient and did not affect cramp frequency in the other 4 patients. Predialysis plasma renin activity (PRA) averaged 3.9 ng/ml/h (+/- SD) and was the same as in unselected hemodialysis patients. Following captopril, PRA increased by an average of 2.2 +/- 0.7 times, similar to the 2.6-fold increase that was reported when this drug was used to prevent dialysis-associated hypertensive crises. However, hemodialysis by itself did not activate the renin-angiotensin system as consistently in patients with frequent dialysis-associated skeletal muscle cramps as in unselected hemodialysis patients and the ratio of post- to predialysis PRA averaged 1.0 +/- 0.6. We conclude that the renin-angiotensin system does not mediate, and that its activation during hemodialysis may actually help prevent, dialysis-associated skeletal muscle cramps.

Aged↗
PubMed1988

Central nervous system and cardiac manifestations of hydrochlorothiazide overdosage; treatment with hemodialysis.

A patient with end-stage renal failure inadvertently received high-dose hydrochlorothiazide as treatment for hypertension, resulting in CNS and cardiac toxicity. These toxic manifestations were successfully treated with hemodialysis. A hydrochlorothiazide dialysance of 62.5 mL/min was demonstrated. The possibility of hydrochlorothiazide toxicity should be considered in any patient with renal insufficiency who exhibits unexplained arrhythmias or symptoms related to the CNS.

Aged↗
PubMed1988

Effect of high salt intake on sodium, potassium-dependent adenosine triphosphatase activity in the erythrocytes of normotensive men.

1. We measured ouabain-insensitive adenosine triphosphatase (ATPase), sodium, potassium-dependent adenosine triphosphatase (Na+,K+-ATPase) and intracellular Na+ and K+ in the erythrocytes of 19 healthy volunteers, before and after supplementation of their normal diet was 6.0-8.9 g of salt (102-137 mmol of NaCl) per day, for 5 days. 2. The subjects had a small but significant gain in weight. Mean plasma renin activity decreased from 1.57 to 0.73 pmol of angiotensin 1 h-1 ml-1 and plasma aldosterone from 0.46 to 0.24 nmol/l. 3. Total ATPase activity fell from 197.9 nmol of inorganic phosphate h-1 mg-1 during the control period to 173.5 during the high-salt period (P less than 0.0125). Na+, K+-ATPase activity fell from 162.2 to 141.4 nmol of inorganic phosphate h-1 mg-1 (P less than 0.05). Intracellular Na+ and intracellular K+ did not change. 4. These results are consistent with the hypothesis that salt-induced volume expansion causes the release of a factor inhibitory to the Na+ pump.

Adult↗
PubMed1984

Somatomedin inhibitor in uremia.

In uremia, poor growth occurs despite normal to increased levels of insulin and GH. Since serum somatomedin levels measured by RIA and radioreceptor assay are normal in patients with renal failure, while serum somatomedin activity measured by bioassay is low but increased by dialysis, we asked if somatomedin activity could be decreased due to the presence of a low mol wt inhibitor(s). Serum was obtained from eight normal adults and eight uremic patients before hemodialysis treatment and was fractionated by gel filtration. Somatomedins and high mol wt inhibitors were separated on Sephadex G-50, pH 2.4, and high and low mol wt inhibitors were separated on Sephadex G-25, pH 7. Somatomedins were measured by stimulation of SO4 uptake by hypophysectomized rat costal cartilage in vitro, and inhibitor levels were determined by the blunting of stimulation produced by somatomedins in normal serum. Total biologically active somatomedin levels were comparable in uremic and normal sera. High mol wt somatomedin inhibitors (as found in malnutrition and diabetes) also were detected at similar levels in uremic and normal sera. In contrast, serum from uremic patients had increased levels of a low mol wt somatomedin inhibitor(s) [151 +/- 23% (mean +/- SEM) of serum stimulation inhibited vs. 47 +/- 9%; P less than 0.001]. Peak inhibitory activity was found at approximately 940 mol wt (range, 800-1100); an inhibitor of similar size was found in normal urine. Uremic serum fractions blunted cartilage sulfate uptake that was stimulated by whole serum, somatomedins (dissociated from serum carrier proteins), and insulin and lowered uridine and thymidine uptake that was stimulated by whole serum (all P less than 0.005). Lineweaver-Burk analysis indicated that somatomedin-inhibitor interactions on cartilage were noncompetitive, consistent with observations that direct exposure of cartilage to inhibitor decreased SO4 uptake to 30 +/- 3% below buffer levels (P less than 0.001). Despite these marked effects on cartilage, no alterations in basal or insulin-stimulated glucose oxidation occurred after addition of inhibitory serum fractions to adipose tissue incubations. Exposure of the inhibitor to proteolytic enzymes led to a significant decrease in inhibitory activity, indicating that the inhibitor may be a peptide. These studies suggest that decreased circulating somatomedin activity and impaired growth in uremia may reflect the accumulation of a circulating peptide inhibitor that would normally be cleared by the kidneys. Measurements of this factor may provide an index of growth potential in uremic children and help guide therapy of renal failure in both children and adults.

Adult↗
PubMed1983

Propranolol-hydralazine combination in essential hypertension.

The efficacy of a propranolol-hydralazine combination tablet was compared with that of each of its two components in the twice-daily treatment of mild to moderate essential hypertension (diastolic blood pressure: 100 to 125 mmHg). After a three-week, single-blind, placebo period, a 9- to 18-week, single-blind, dose-finding phase with the combination was performed. The daily doses of propranolol/hydralazine were 40 mg/25 mg, 80 mg/25 mg, 80 mg/50 mg, 120 mg/50 mg, 160 mg/50 mg, and 160 mg/100 mg. Of 83 patients, 73 (88%) had decreases in diastolic blood pressure equal to or greater than 10 mmHg. Thirty-eight (46%) patients had a diastolic blood pressure equal to or less than 90 mmHg while taking 80 mg propranolol/50 mg hydralazine or less given BID. Mean systolic and diastolic pressures were reduced by 16.8 mmHg (10.9%) and 17.6 mmHg (16.7%), respectively (P less than 0.001). A ten-week, double-blind, parallel-treatment phase followed in which patients were randomly assigned to the combination tablet or to propranolol or hydralazine. There were significantly larger increases in mean systolic (P less than 0.01) and mean diastolic (P less than 0.03) blood pressure when the components were taken alone than with the combination from the mean of the last three weekly dose-finding visits to the mean of the last four biweekly parallel-treatment visits. The changes in systolic/diastolic blood pressures were: hydralazine (n = 30), 14.43/8.62 mmHg; propranolol (n = 24), 9.87/6.09 mmHg; and the combination (n = 27), 1.47/1.53 mmHg. During the parallel-treatment phase, the proportions of patients with new complaints were: hydralazine, 16/31 (52%); propranolol, 10/25 (40%); and the combination, 11/27 (41%). In the hydralazine group, three patients had cardiovascular events (severe tachycardia, mild palpitations, and skipped heart beats) and two patients had mild anxiety; no such occurrences were noted in the propranolol or combination group. The mean change (increase) in heart rate from the end of dose-finding to the end of the double-blind period was significantly larger for patients taking hydralazine than for patients taking propranolol or the combination. Mean changes for these groups were: hydralazine, 12.4 beats/min; propranolol, 2.9 beats/min; and the combination, 1.8 beats/min (P = 0.0001). This study found the combination of propranolol plus hydralazine to be safe and more effective than either component.

Adult↗
PubMed1981

Comparison of antihypertensive effects of captopril and propranolol in essential hypertension.

The antihypertensive effects of the oral converting enzyme inhibitor captopril and of propranolol were evaluated in a single-blind trial of 12 weeks in 19 ambulatory men with moderated essential hypertension (supine diastolic blood pressure [DPB], 100 to 120 mm Hg after receiving placebo for two weeks) whose sodium intake was unrestricted. The captopril group included 12 patients and the propranolol group seven. After the initial dose-finding period of four weeks, supine DBP was significantly reduced in eight patients receiving captopril and in four of the patients receiving propranolol. In these patients DBP decreased throughout the following eight weeks. In the remaining patients from each group, DBP was not reduced by either drug given alone at maximum allowable dosages during dose-finding periods, nor by combined administration in following weeks. No adverse side effects attributable to captopril were noted, except in one patient in whom proteinuria developed after seven weeks. Captopril has potential value in the treatment of moderate essential hypertension.

Adult↗
PubMed1981

Hemodialysis vs. peritoneal dialysis: results of a 3-year prospective controlled study.

A prospective comparison of peritoneal dialysis to hemodialysis was undertaken to identify advantages and disadvantages of either treatment relative to the other. Hematologic, biochemical, lipid, and neurobehavioral parameters were followed. Careful controls were imposed to assure that the treatment groups were comparable. Patients on peritoneal dialysis proved to have more normal concentrations of BUN, hemoglobin, potassium, bicarbonate, and high-density lipoproteins. Hemodialysis patients had more normal concentrations of albumin, total protein, and calcium. Hypertriglyceridemia was only minimally greater in peritoneal patients. Neurobehavioral results documented multiple abnormalities in both. The profile of results obtained provides preliminary criteria for selecting either form of dialysis for a particular patient.

Adult↗
PubMed1981

Rationale and application of beta-2-microglobulin measurements to detect acute transplant rejection.

Serum and urinary concentrations of beta 2-microglobulin were measured for the first 21 days after renal transplantation to aid in diagnosis of acute rejection. Criteria developed after study of 15 patients were applied to the entire group of 31 consecutive cases. 29 instances meeting our criteria were identified in 651 days at risk and were associated with a mean maximal increase of serum creatinine of 74.8%. beta 2-Microglobulin methods may make possible detection of what is now subclinical rejection. beta 2-Microglobulin methods, however, are an adjunct to, not a replacement for classical methods for detecting acute rejection.

Beta-Globulins↗
PubMed1981

Tissue and glomerular deposition of globulin aggregates.

We studied the behavior of AgGG, a model of iCs, in the rat. The clearance of radiolabeled AgGG from the circulation was found to follow first-order kinetics. The t1/2 of the AgGG increased markedly with increases in dose administered, whereas the absolute rate of removal appeared to approach a maximum. The bulk of the AgGG cleared was found in the liver, and less than 1% was found in spleen, lung, or kidney. All these features are typical of the behavior of macromolecules removed from the circulation by the RES. Specific glomerular deposition was studied at various dosages by isolating glomeruli and measuring the fraction of injected aggregate that was trapped. This fraction represented less than 10% of total renal deposits. Moreover, when animals were sacrificed at an interval of 1 t1/2 after the injection of the corresponding dose, the fraction deposited in glomeruli remained constant. The significance of this finding is discussed in relation to the pathogenesis of glomerulonephritis.

Animals↗
PubMed1981

Long-term treatment of hypertension with methyldopa. IV. Duration of methyldopa therapy.

Methyldopa was administered for an average of 3 years to 435 patients with essential hypertension who were included in this retrospective survey. In 73% of patients, methyldopa was added to prior diuretic therapy, and in 19%, methyldopa and a diuretic were started concurrently. The remaining patients (8%) started treatment with methyldopa alone. After the initiation of methyldopa administration, a diuretic and/or additional antihypertensive agent(s) was included in the treatment regimen of 167 (38%) of the 435 patients. Treatment was interrupted in 147 patients - 14 (3%) because of lack of response, 73 (17%) with adverse effects, and 60 (14%) because of other or unknown reasons. Two-thirds of the patients treated had been receiving methyldopa continuously up to the time these data were collected in early 1979.

Adolescent↗
PubMed1980

Hemodialysis-exchange transfusion for treatment of thrombotic thrombocytopenic purpura.

Remission in thrombotic thrombocytopenic purpura (TTP) was achieved in two patients after repeated exchange transfusion. Since both patients had renal insufficiency, exchange was performed with hemodialysis. This provided optimal volume control and facilitated the rapid exchange of blood. The infusion of plasma did not maintain the clinical improvement achieved with exchange transfusion. Until a concentrate of the putative factor deficient in TTP becomes available, an exchange procedure remains the most expeditious method for the replacement of any deficient factor. The procedure of hemodialysis can be adapted to perform exchange transfusion safely and efficiently.

Acute Kidney Injury↗
PubMed1980

Symptomatic Acinetobacter calcoaceticus peritonitis. "A complication of peritoneal dialysis".

Acinetobacter Calcoaceticus peritonitis was seen during the course of peritoneal dialysis in two patients with end-stage kidney disease within a 3-month period. In one patient, the isolate was A. Calcoaceticus Varient Anitratus (formerly Herellea Vaginicola) and in the other it was A. Calcoaceticus Lwoffi (formerly Mima Polymorpha). Both were successfully treated with continuous peritoneal antibiotic lavage.

Acinetobacter Infections↗
PubMed1980

Elevated beta-thromboglobulin in patients with chronic renal failure: effect of hemodialysis.

Elevated plasma concentrations of beta-thromboglobulin were observed in 25 consecutive patients with chronic renal failure. Further increases in this platelet protein were observed during hemodialysis but not during peritoneal dialysis. The hemodialysis-induced increases were not prevented by either aspirin or dipyridamole, a fact which suggested that release of this protein was not dependent on platelet functional activity. Measurement of beta-thromboglobulin provides a sensitive indicator of platelet disruption during hemodialysis.

Adolescent↗