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Biomedical subjects

G Gaspar

Publications and source records attributed to G Gaspar.

At least 37 records · Page 2Linked to original sources
PubMed1984

Renal handling of uric acid in patients with recurrent calcium nephrolithiasis and hyperuricosuria.

Hyperuricosuria is a frequent finding in patients with recurrent calcium nephrolithiasis (RCN) that has been related to purine overingestion . The influence of diet and the renal handling of uric acid were investigated in patients with RCN to assess the pathogenic mechanism of excessive urate excretion. Among 50 patients with recurrent nephrolithiasis 42 formed renal stones containing calcium and 9 of these 42 patients demonstrated concomitant asymptomatic hyperuricosuria while on a self-selected diet. Ingestion of a purine-free diet normalized the uric acid excretion in 4 of these 9 patients. The other 5 patients showed persistent hyperuricosuria while on a purine-free diet. In order to assess a possible dysfunction in the renal handling of uric acid, pharmacological tests were undertaken in these 9 patients. Pyrazinamide administration almost completely suppressed urate excretion, excluding a presecretory reabsorption defect. Urate excretion in response to probenecid administration was decreased in 4 patients and increased in 1. This finding is in accordance with a postsecretory reabsorption defect in the former and an augmented tubular secretion of urate in the latter. This study proves that both dietary factors and tubular transport defects are involved in patients with recurrent calcium nephrolithiasis and hyperuricosuria.

Adult↗
PubMed1984

Renal tubular acidosis in recurrent renal stone formers.

Renal tubular acidosis (RTA) is a well-known metabolic disturbance that may promote recurrent renal stone formation. However, its incidence, screening criteria and association with other lithogenic metabolic abnormalities are not established in recurrent nephrolithiasis. 10 of 50 consecutive recurrent renal stone formers had a persistent fasting morning urinary pH above 6.0 and/or a basal plasma bicarbonate concentration below 20.0 mM. Acid and alkaline loads disclosed RTA in 3 patients: 1 patient had incomplete type-1 distal RTA in addition to hyperoxaluria; a second patient showed complete type-2 proximal RTA, hyperoxaluria and renal hypercaliuria; and a third patient had incomplete proximal RTA without any other metabolic derangement. These results reinforce the importance of RTA as an isolated metabolic abnormality among recurrent renal stone formers. In addition, RTA appears to be more commonly associated with other lithogenic metabolic derangements than has been previously suspected. The extensive metabolic protocol used in this study provides a useful tool in the diagnosis and therapeutic considerations of recurrent nephrolithiasis.

Acidosis, Renal Tubular↗
PubMed1983

Renal handling of uric acid in normal subjects by means of the pyrazinamide and probenecid tests.

Pyrazinamide and probenecid tests were used to study the renal mechanisms for urate excretion in 10 normal subjects in the state of low serum uric acid levels (below 3.5 mg/dl), normal serum urate concentrations (between 3.6 and 6.4 mg/dl) and high serum uric acid levels (above 6.5 mg/dl). Presecretory reabsorption of urate was above 99% in all three conditions of uricemia, indicating that filtered urate is nearly completely reabsorbed in the proximal tubule regardless of serum uric acid concentrations. Urate secretion was significantly higher and postsecretory reabsorption was significantly lower when serum uric acid was raised than when serum urate levels were normal or low. The findings indicate that both urate secretion and postsecretory reabsorption play a role in urate homeostasis in states of hyperuricemia.

Adult↗
PubMed1981

Renal tubular function and urinary acidification capacity in early juvenile diabetes.

Renal elimination of uric acid, calcium, phosphorus, sodium, potassium, chloride and magnesium and urinary acidification capacity were determined in ten insulin-dependent diabetics and in ten matched control subjects. The diabetics showed excessive excretion of uric acid, sodium, potassium, chloride and ammonia. Sodium, chloride and ammonia excretion fractions was also increased with respect to controls. The enhanced excretion of these substances in diabetics failed to relate to glomerular filtration rate, glycosuria or insulin requirements. These findings might be explained on the basis of glomerular filtration rate elevation, tubular response to this increment, and the underlying metabolic disturbances of diabetes.

Adolescent↗
PubMed1977

Incorporation and metabolism of stearic, oleic, linoleic and alpha-linolenic acids in minimal deviation hepatoma 7288 C cells.

Minimal Deviation Hepatoma 7288 C cells were cultured in confluent layer with labeled stearic, oleic, linoleic and alpha-linolenic acids. The kinetics of incorporation and conversion to higher homologs was studied. The maximum amounts incorporated in nmoles per mg of cellular protein for stearic, oleic, linoleic and alpha-linolenic acids were 39, 115.6, 90 and 230 respectively. alpha-linolenic acid was converted to octadeca-6,9,12,15-tetraenoic acid (18:1), eicosa-11,14,17-trienoic acid (20:3), eicosa-8,11,14,17 and 5,11,14,17-tetraenoic acids (20:4) and eicosa-5,8,11,14,17-pentaenoic acid (20:5), and also to myristic, palmitic, palmitoleic, stearic and oleic acids. By a mathematical approach, the endogenous pool size of alpha-linolenic acid available for conversion to eicosa-5,8,11,14,17-pentaenoic acid, were calculated. Both values decreased when the cells were preincubated with unlabeled alpha-linolenic acid.

Carcinoma, Hepatocellular↗
PubMed1975

Uptake and metabolism of exogenous eicosa-8,11,14-trienoic acid in minimal deviation hepatoma 7288 C cells.

Minimal deviation hepatoma 7288 C cells were cultured in Swim's medium containing 10% serum for 48 hr. The growth medium was replaced with serum free media containing different concentrations of [1-14C] eicosa-8,11,14-trienoic acid and the cells were incubated for 24 hr. Incorporation into cell lipids, oxidation to CO2, and desaturation to arachidonic acid were studied. The oxidation of the acid was very low. It was preferentially incorporated into the polar lipids of the cell. The incorporation depended on the number of cells and fatty acid concentration. Saturation of the cells with the acid was reached when 144.7 nmoles per mg of cellular protein were incorporated. The acid was desaturated readily to arachidonic acid. The nmoles of eicosatrienoic acid converted to arachidonic acid per mg of cellular protein were hyperbolic function of the acid incorporated. Maximal desaturation, 23 nmoles per mg of cellular protein, was reached when the cells were saturated with the acid. The calculations of the desaturation capacity and of the endogenous pool of eicosatrienoic acid available for desaturation in the cell are discussed.

8,11,14-Eicosatrienoic Acid↗
PubMed1975

[Effect of an essential fatty acids free diet on the lipidic composition of rat testicles (author's transl)].

The effect of a fat free diet on the fatty acid composition and histological changes of the testis of old rats was studied to investigate the possible function of docosa-4,7,10,13,16-pentaenoic acid in rat testicles. The lipidic composition, the fatty acid composition, the conversion of docosa-7,10,13,16-tetraenoic acid to arachidonic acid and the activity of the 6-desaturase were determined during the different periods in which the rats received a fat free diet. Comparatively, the changes in the fatty acid composition of the liver were also studied. Only the liver showed a change in the triglyceride content during the first month of treatment, and it regained its normal values afterwards. Both liver and testis changed the fatty acid composition. An increase of the acids of the oleic series and a decrease of the components of the linoleic series were shown. These changes were similar to the ones provoked by an essential fatty acid deficient diet on young animals. The amount of docosa-4,7,10,13,16-pentaenoic acid was very little changed. No significant change was shown either in the retroconversion of docosa-7,10,13,16-tetraenoic acid to arachidonic acid. However, the 6-desaturase activity of the testis was enhanced by the fat deficient diet. The possibility that arachidonic acid in the adult rat is mainly supplied by linoleic acid and not by the retroconversion of docosa-4,7,10,13,16-pentaenoic acid is discussed.

Animals↗