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Biomedical subjects

C A Vaamonde

Publications and source records attributed to C A Vaamonde.

At least 19 recordsLinked to original sources
PubMed1992

The protection against gentamicin nephrotoxicity in the streptozotocin-induced diabetic rat is not related to gender.

Since gender can influence the renal toxicity of a drug in a given species, the present study was undertaken to evaluate the role of sex in the protection against gentamicin (G)-induced nephrotoxicity afforded by diabetes mellitus (DM) in the rat. We have compared the effects of administration of G (40 mg/kg/day, for 14 days) on male and female DM Sprague-Dawley rats. Non-diabetic animals of both sexes receiving identical doses of G served as controls. At the end of the experiment on day 14, both female (F) and male (M) control groups had similar and marked evidence of nephrotoxicity: elevation of plasma creatinine (F 1.7 +/- 0.7; M 2.8 +/- 0.6 mg/dl), decrease in endogenous 24-h creatinine clearance (Ccr) (F0.3 +/- 0.1; M 0.2 +/- 0.1 ml/min/100 g BW), and histological evidence of severe acute tubular necrosis. In marked contrast, the DM rats showed no functional or morphological evidence of renal damage throughout the study regardless of their gender (day 14: plasma creatinine: F 0.2 +/- 0.03; M 0.2 +/- 0.02; Ccr: F 1.2 +/- 0.1; M 1.6 +/- 0.1 ml/min/100 g BW), and they also accumulated less G in their kidney cortex than the C rats. The male controls exhibited higher renal cortex accumulation of G than the female controls (p < 0.05), whereas the opposite occurred in the DM groups (p < 0.01). Because the validity of using Ccr for the evaluation of GFR changes in experimental nephrotoxicity has been questioned, we have compared, in a separate experiment, three different methods of estimation of GFR (simultaneous short clearances of inulin and Ccr, and 24-h Ccr) in conscious female Sprague-Dawley rats undergoing the same treatment with G described above. At no time during the study did the method used for estimation of the GFR influence the results. We conclude that male and female Sprague-Dawley rats with diabetes are functionally and morphologically equally protected against G. Furthermore, no gender-related differences in the magnitude of G-induced nephrotoxicity was demonstrated in the non-diabetic control animals.

Animals↗
PubMed1990

Hepatitis C infection in two urban hemodialysis units.

We determined the prevalence of antibodies to the hepatitis C virus (anti-HCV) in 90 patients and 37 staff members of two hemodialysis units utilizing a recently developed anti-HCV recombinant based assay. Eleven patients (12%) were anti-HCV(+). Of these, eight (73%) had antibodies to the hepatitis B core antigen (anti-HBc) indicating prior hepatitis B infection; one patient was hepatitis B surface antigen (HBsAg)(+). All staff members were anti-HCV(-), although seven (19%) of them were anti-HBc(+). Alanine aminotransferase elevations were present at the time of the study in four anti-HCV(-) patients and in only one anti-HCV(+) patient. All anti-HCV(+) (mean 59 +/- 74; range 3 to 269 units) and 85% of anti-HCV(-) patients (mean 16 +/- 27; range 0 to 204 units) had received multiple blood transfusions (P = 0.348). Among 50 patients tested for human immunodeficiency virus (HIV), 43% of anti-HCV(+) as compared to only 7% anti-HCV(-) were positive (P = 0.003). There was a history of intravenous drug abuse (IVDA) in eight (72%) of the anti-HCV(+) patients and in only seven (9%) of the anti-HCV(-) group (P = 0.00001). The results of this serologic survey suggests that anti-HCV positivity is prevalent, although much less than anti-HBc, among our dialysis patients, whereas it was not detected among staff members. The prevalence rate of anti-HCV was statistically significantly higher among anti-HIV(+) and IVDA patients but not in multi-transfused patients.

Adult↗
PubMed1990

Influence of magnesium sulfate-induced hypermagnesemia on the anion gap: role of hypersulfatemia.

Although hypermagnesemia purportedly lowers the anion gap (AG), we have shown previously that increases in the serum concentration of the unmeasured cation (UC) Mg due to therapeutic infusion of MgSO4 are not associated with AG reduction. To assess our hypothesis that increases in serum SO4 (unmeasured anion, UA) offset the effect of elevated serum Mg on the AG, we prospectively studied 11 patients receiving MgSO4 intravenously for toxemia of pregnancy. After 6 h of MgSO4 infusion, serum Mg increased by 2.1 +/- 0.2 (SE) mEq/l (p less than 0.001) without a significant decrease in the AG. Concomitantly, serum SO4 increased by 1.4 +/- 0.2 mEq/l. Comparison of the renal handling of SO4 versus Mg showed a higher fractional excretion of the former, probably accounting in part for the smaller increment of serum SO4 than of Mg. Comparison of the change in serum SO4 minus that of Mg indicated that, on the average, 70% of the observed 1.0 +/- 0.7 mEq/l reduction in AG was accounted for by the observed changes in the two pertinent unmeasured ions. A small decrement in serum Ca probably was a quantitatively minor factor tending to obviate a greater decrease in AG. We conclude that hypersulfatemia attenuates the reduction in AG that would otherwise accompany MgSO4-induced hypermagnesemia.

Acid-Base Equilibrium↗
PubMed1979

Impaired renal bicarbonate reabsorption in the hypothyroid rat.

We previously demonstrated a decrease of sodium reabsorption in the proximal superficial nephron of the hypothyroid rat. The present clearance studies were designed to examine the renal handling of bicarbonate in hypothyroid rats. Hypothyroidism was induced by the intraperitoneal injection of Na131I and the animals were studied 10 or more wk thereafter under anesthesia and compared to their age-matched litter-mates. As is characteristic of hypothyroid animals, insulin clearance was lower and fractional urine flow and sodium excretion rates were higher than in the control rats. At the peak of the bicarbonate diuresis and at similar blood pH, PCO2, and bicarbonate levels, fractional renal bicarbonate excretion was significantly higher in the hypothyroid animals: 22 +/- 2 vs. 15 +/- 1%, P less than 0.02. This perturbation of bicarbonate reabsorption of the hypothyroid rats was independent of the influence of extracellular fluid volume expansion and appears closely related to the impaired sodium reabsorptive capacity characteristic of experimental hypothyroidism.

Animals↗
PubMed1979

The effect of acute metabolic acidosis on plasma cortisol, renin activity and aldosterone.

The effect of metabolic acidosis on the renin-aldosterone system remains unclear. In the present study anesthetized mongrel dogs (n = 19) were infused at similar rates with 0.45% NaCl (controls), HCl or NH4Cl (2.5mEq/kg) for 1--3 h. The induced metabolic acidosis in the two experimental groups was not associated with increases in plasma renin activity. Plasma cortisol (as a marker for ACTH secretion) and serum potassium concentration increased in both HCl- and NH4Cl-treated animals. Plasma aldosterone increased after 30 min in the HCl group and 60 min in the NH4Cl group and did not change in controls. These findings demonstrate that metabolic acidosis induced by HCl or NH4Cl is associated with increased aldosterone production without concomitant changes in plasma renin activity.

Acidosis↗
PubMed1979

Circulating levels of vasoactive intestinal polypeptide in liver disease.

In animals, the effects of vasoactive intestinal polypeptide (VIP) include peripheral vasodilation, hyperdynamic circulation, hyperglycemia, and hyperventilation. Because these phenomena are noted in patients with cirrhosis, it has been postulated that VIP might be escaping hepatic inactivation and entering the systemic circulatory system and contributing to these abnormalities. The major purpose of this study is to establish whether or not VIP levels are elevated in patients with cirrhosis. Additional goals are to determine if VIP levels are elevated in acute liver disease and in chronic illnesses with secondary liver involvement. The data demonstrate that patients with cirrhosis and those with acute liver disease or chronic illnesses with secondary hepatic involvement have a wide range of VIP levels with mean values significantly above that of normal individuals and patients with chronic illness and no liver involvement.

Acute Disease↗
PubMed1978

Relationship between blood pH and potassium and phosphorus during acute metabolic acidosis.

Metabolic acidosis is known to be associated with increased blood potassium and phosphorus concentrations but the influence of mineral versus nonmineral acids on these variables remains undefined. Therefore, we infused anesthetized mongrel dogs with 0.45% saline (controls), the mineral acids HCl and NH4Cl, and the nonmineral acids lactic, beta-hydroxybutyric and methyl malonic for 1-3 h. Administration of both mineral acids was associated with significant increases in plasma potassium. In contrast, infusion of the three monmineral acids did not result in increases in plasma potassium; in fact, the levels decreased initially in the majority of the dogs. Phosphorus concentrations were increased by lactic and beta-hydroxybutric acids, were unchanged by NH4Cl and HCl, and were decreased by methyl malonic acid. Although the mechanisms responsible for these changes remain to be elucidated, the findings indicate that short-duration infusion of mineral and nonmineral acids has substantially different effects on plasma concentrations of these predominantly intracellular ions.

Acidosis↗
PubMed1978

Renin-aldosterone responsiveness in uncomplicated juvenile-type diabetes mellitus.

The changes in plasma renin activity (PRA) and plasma aldosterone concentration (PA) in response to dietary sodium restriction and upright posture were evaluated in 7 patients with juvenile-type, insulin-dependent, uncomplicated diabetes mellitus and in 5 healthy volunteers. All patients had normal blood pressure, 24-hour urine protein excretion and endogenous creatinine clearance. Renal sodium conservation and concentrating ability were grossly normal and 5 patients so tested, had normal renal acidification. PRA and PA were normal in every subject suggesting that abnormalities of the renin-aldosterone axis are late complications of diabetes mellitus usually associated with hypertension and nephropathy or neuropathy.

Adult↗
PubMed1977

Effect of long-term lithium administration on renal phosphorus handling.

Renal phosphorus handling was evaluated in 12 lithium carbonate-treated psychiatric patients. Serum phosphorus was normal and serum lithium values were within the therapeutic range in all subjects. Serum calcium concentrations measured in 6 of the patients were found to be within the normal range; in the same patients serum parathyroid hormone levels were normal in 4 and slightly elevated in 2. Phosphorus clearance (14 +/- 3 [se] ml/min) and tubular reabsorption of phosphorus (88 +/- 2%) during oral sodium bicarbonate loading were not significantly different from those in 10 healthy control subjects. In a subgroup of 5 patients and 5 control subjects, phosphorus excretion did not increase after bicarbonate loading. In these subjects, phosphorus excretion rates after bicarbonate loading were not different. Although experimental studies suggest that lithium inhibits renal cortical adenylate cyclase stimulation by parathyroid hormone, our data did not indicate any striking effect of long-term lithium administration on serum calcium and serum phosphorus or on renal phosphorus handling.

Adenylyl Cyclase Inhibitors↗
PubMed1977

Peritoneal dialysis. Current status.

Peritoneal dialysis has a definite role in the treatment of acute or chronic renal failure and certain fluid and electrolyte disturbances. Its major advantages are simplicity and availability. On the other hand, it is less effective and causes more patient discomfort than hemodialysis. Many factors enter into the decision to use one method of dialysis or the other, and the two should be considered complementary. The numerous complications that may occur during peritoneal dialysis can be avoided by careful attention to technical details. With the recent development of indwelling catheters and automatic cycling devices, long-term peritoneal dialysis is being used increasingly and successfully in the home, particularly in patients for whom home hemodialysis is difficult or inappropriate.

Abdominal Injuries↗
PubMed1977

Effect of alterations of sodium intake in patients with hyporeninemic hypoaldosteronism.

The effect of changes of sodium intake on serum and urinary electrolytes, plasma renin activity (PRA) and plasma aldosterone concentration (PA) was studied in five hyperkalemic patients with the syndrome of hyporeninemic hypoaldosteronism (SHH). The patients were evaluated during 8 days on a 10-mEq sodium and 50-mEq potassium diet plus furosemide, followed by 8 days on a 150-mEq sodium and 50-mEq potassium diet. After sodium depletion, both PRA and PA were substantially higher than after a previous 4-day period of simple dietary sodium restriction and an increase in serum potassium concentration occurred in only one subject. Administration of a normal sodium intake induced small increases in serum chloride in all five subjects and a decrease in bicarbonate concentration in one patient. It is concluded that, at least in some patients with SHH, PRA and PA are volume-responsive and that considerable alterations of sodium intake have relatively little influence on serum electrolyte concentrations.

Aged↗
PubMed1977

Urinary carbon dioxide tension in lithium carbonate-treated patients.

Renal acidification was studied in 12 lithium carbonate-treated psychiatric patients. The urinary Pco2 response to oral sodium bicarbonate loading, a qualitative index of distal hydrogen ion secretion, was evaluated in all patients and the results were compared with those obtained in 10 control subjects. The average maximal urine to arterial blood Pco2 difference (U-A Pco2) in the psychiatric patients [26 +/- 3 (S.E.) mm Hg] was significantly lower (P less than .001) than that of control subjects (51 +/- 3 mm Hg) and only three patients had values greater than 31 mm Hg (2 S.D. below the mean control value). Eight of these patients were also evaluated with NH4CL acid loading. Seven of eight patients had a minimal urine pH less than 5.30 after NH4CL administration; only one of the seven had a normal U-APco2 after bicarbonate loading. Three patients were evaluated prior to treatment and after 2 weeks of lithium administration. Pretreatment U-APco2 values were normal. After therapy the values were lower in all three patients becoming definitely abnormal in two. The present investigation, in concert with previous animal studies, demonstrates that chronic lithium carbonate therapy in man may result in decreased U-A Pco2.

Adult↗