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Biomedical subjects

T F Yü

Publications and source records attributed to T F Yü.

16 recordsLinked to original sources
PubMed1979

Renal function in gout. V. Factors influencing the renal hemodynamics.

Renal hemodynamics as measured by inulin clearance (Cinulin) and para-aminohippurate clearance (CPAH) was evaluated in 149 patients with primary gout over intervals of two to 22 years. In over 30 per cent of the patients plasma urate was greater than 10 mg/dl and urinary uric acid greater than 800 mg/min. A linear trend in decreasing frequency of hyperuricemia and excessive uricosuria is significantly related to the patient's age at the onset of gout. Group I consisted of 84 patients with uncomplicated gout in both clearance studies. Cinulin and CPAH were somewhat lower in patients larger than or equal to 50 years of age with longer duration of gout. Further reduction in clearances was minimal at the second clearance study in intervals of approximately 10 years. Group II included 27 patients who had no associated disease at the time of the first clearance study but in whom associated disease had developed by the time of the second clearance study. A striking reduction in Cinulin and CPAH was noted, especially in those 50 years old or above. There were 38 patients in group III with associated diseases at the time of both clearance studies. They had lower Cinulin and CPAH at the time of the first study, particularly the older patients. Further reduction during the second study was less striking than that in group II. Analyses of variance suggest that various coexisting vascular diseases with associated nephropathy have the most significant impact on the status of renal function in gout, with aging the second most important and duration of gout, the third.

Adult↗
PubMed1978

Mass fragmentographic determination of pyrazinamide and its metabolites in serum and urine.

A combined gas chromatographic-mass spectrometric technique is described for the simultaneous determination of pyrazinamide and its two main metabolites, pyrazinoic acid and 5-hydroxypyrazinoic acid. Serum (200 microliter) is deproteinized and evaporated to dryness; urine (20 microliter) is evaporated. The crude residues are silylated and selected ions are monitored in the chemical-ionization mode with isobutane as both chromatographic carrier and reagent gas. The sensitivity is 10 ng/ml for pyrazinamide and pyrazinoic acid and 20 ng/ml for the 5-hydroxy metabolite in a single analysis. Nicotinic acid and nicotinamide are internal standards. Both unchanged drug and metabolites were identified and quantified in the serum and urine of human subjects.

Gas Chromatography-Mass Spectrometry↗
PubMed1978

Uric acid metabolism in homozygous and heterozygous muscular dystrophic mice.

The homozygous muscular dystrophic mice (dydy) were found to have significantly higher plasma uric acid than their heterozygous littermate controls (Dydy), and the Swiss albino mice. Because the rate of uric acid excretion did not compensate for the elevated plasma levels, U/P (urine/plasma) urate was lower in dydy mice. With RNA supplement, plasma and urinary urate were increased in both dydy and Dydy mice; again U/P urate was lower in dydy mice. It appears that the dydy mice to a certain extent are comparable to some gouty subjects, whose hyperuricemia is not accompanied by a corresponding increase in urinary uric acid. There was no difference in converting uric acid to allantoin either on basal diet alone or with RNA supplement. Oxonic acid effectively, though transiently, blocked the uricase activity in both dydy and Dydy mice resulting in hyperuricemia and hyperuricosuria with decreased allantoin. Uric acid content was increased markedly in the kidney without histological evidence of urate deposition, apparently related to the unsustained effect of oxonic acid, which was rapidly excreted.

Allantoin↗
PubMed1977

Preliminary criteria for the classification of the acute arthritis of primary gout.

The American Rheumatism Association sub-committe on classification criteria for gout analyzed data from more than 700 patients with gout, pseudogout, rheumatoid arthritis, or septic arthritis. Criteria for classifying a patient as having gout were a) the presence of characteristic urate crystals in the joint fluid, and/or b) a topus proved to contain urate crystals by chemical or polarized light microscopic means, and/or c) the presence of six of the twelve clinical, laboratory, and X-ray phenomena listed in Table 5.

Acute Disease↗
PubMed1977

The effect of the interaction of pyrazinamide and probenecid on urinary uric acid excretion in man.

Complex interactions occur between pyrazinamide (PZA) and probenecid in man involving both the metabolism and distribution of the drugs, and their effects on renal tubules. Pretreatment with PZA prolonged the half-life (T 1/2) of probenecid without changing its plasma-binding. As the rate of probenecid metabolism is decreased, its uricosuric action tends to be prolonged and the effect of PZA lessened. The PZA-suppressible urate level is increased to values well above control after the administration of probenecid; it is less after alkalinization of urine, although still larger than the value for PZA-suppressible urate after the administration of PZA alone. Urinary probenecid excretion is much greater when urine is alkalinized. These observed drug interactions, plus the known effect of probenecid to block secretion of PZA, have to be considered in evaluating the effect of the two drugs given together, compared to the effect of each drug given separately.

Adult↗
PubMed1977

The effect of ascorbic acid on uric acid excretion with a commentary on the renal handling of ascorbic acid.

Under spontaneous conditions in man and dog, very little ascorbic acid is excreted in urine. Ascorbic acid clearance (C ascorbic acid) is promptly augmented when plasma ascorbic acid is increased by intravenous injection. No net tubular secretion of ascorbic acid is demonstrable in either man or dog when plasma ascorbic acid is elevated to levels as high as 12 mg/100 ml in man, and 28 mg/100 ml in the dog. Nevertheless, both in men and the Dalmatian dog, when the glomerular filtration rate (GFR) is decreased, excreted ascorbic acid in relation to the amount filtered is exaggerated so that C ascorbic acid:GFR approaches unity. It is possible that secreted ascorbic acid is masked under ordinary circumstances, with a more significant contribution of secreted ascorbic acid to total urinary ascorbic acid becoming apparent under conditions of low GFR. In man, when the plasma ascorbic acid level is raised to above 6 mg/100 ml, C urate:GFR rises from control value of 0.081 +/- 0.020, to 0.116 +/- 0.026. In both mongrel and Dalmatian dogs an effect of ascorbic acid on urate excretion is not conclusively shown. The uricosuric effect of ascorbic acid in man may be due to competition with uric acid for renal tubular reabsorptive transport. The difference in the metabolism of ascorbic acid in the dog as compared to man may help account for the inconsistent effect of ascorbic acid on uric acid excretion in the dog.

Aged↗
PubMed1977

Some unusual features of gouty arthritis in females.

Gouty arthritis in females is relatively infrequent, although the sex ratio may be somewhat altered in different races. A positive family history is relatively prevalent among females whose onset of gout is premenopausal. In those patients with a postmenopausal onset, the incidence of diuretic-associated gout is high. The bimodal distribution of serum urate might be related to some variance of genetic transmission in female gout. Hypertension and coronary heart disease are common coexisting conditions, as is true of gouty arthritis in males. Chronic urinary tract infection dating from previous pregnancies is a frequent complication. The relative prevalence of proteinuria and diminished renal function leads to increased hyperuricemia, with a tendency to a low urinary uric acid output. This explains in part the higher incidence of extensive tophaceous deposition but lower incidence of renal calculi. Diuretics are associated with a higher urine pH, likewise, they reduce the urinary uric acid excretion. This also may contribute to the lower incidence of renal calculi. There may be some statistical support for the low fertility rate among the gouty females. Only two females became pregnant after the onset of gouty arthritis. All other pregnancies occurred before the onset of arthritis. Even then, abnormal pregnancies were relatively frequent. Some hormonal malfunction among the gouty females cannot be discounted. Both renal calculi and tophi are frequent in female gout associated with blood dyscrasias. They may manifest early, preceding the first attack of acute gouty arthritis. In both the male and female secondary gout, the primary underlying disease governs the uric acid metabolism and the clinical symptomatology of gout. The predominant role in pathogenesis is the excessive rate of uric acid production, and its disposal is governed by the different stages of the underlying disease and the treatment. Thus, secondary gout in females appears to be somewhat different from primary gout in females, but not different from secondary gout in males.

Adult↗
PubMed1976

Hypoxanthine phosphoribosyltransferase activity in intact fibroblasts from patients with X-linked hyperuricemia.

Discordance between clinical phenotype and the level of a mutant enzyme activity may reflect differences between enzyme function in vivo and that measured by the customary enzyme assays on cell extracts. In the present study, the conversion of hypoxanthine to phosphorylated products was measured in intact skin fibroblasts and in cell extracts from seven patients with mutant hypoxanthine-guanine phosphoribosyltransferase (HPRT) and six control subjects. The patient's phenotypes ranged from asymptomatic hyperuricemia to the Lesch-Nyhan syndrome. Although there was a general correlation between the HPRT activity in cell extracts assayed by the usual methods and the function of the purine salvage pathway in patients, as reflected by urinary oxypurine excretion, there were notable exceptions. A more accurate appraisal of the functioning of the pathway at the cellular level is achieved by measuring the conversion of substrate to product in the intact cell at physiological concentrations of substrates, activators, and product and metabolite inhibitors, and in a physiological ionic environment. In one of the seven patients, the standard enzyme assay indicated normal function, whereas measurements in the intact cell exposed severe dysfunction of the salvage system. In another, the standard assay suggested a severe deficiency not evident in the intact cell or in the patient.

Adolescent↗
PubMed1975

Renal function in gout. IV. An analysis of 524 gouty subjects including long-term follow-up studies.

Renal function studies were performed in 524 gouty subjects, including follow-up studies at intervals up to 12 years in 112 of them. In 49 subjects, the glomerular filtration rate was less than 70 ml/min and Curate:glomerular filtration rate ratio tended to rise as the glomerular filtration rate decreased, reflecting a relatively stable urate excretion over varying filtered urate loads. The increment in Tsurate:glomerular filtration rate was small with spontaneous Purate between 7 and 9 mg/100 ml. It was modest with Purate up to 10 mg/100 ml. The increment in Tsurate:glomerular filtration rate became much higher beyond Purate of 10 mg/100 ml. Urinary urate levels above 800 mug/min, designated as excess urate excretion, occurred more commonly in subjects with Purate above 9 mg/100 ml, and with better preserved renal function. Tophi were more frequently observed in subjects with low glomerular filtration rate and proteinuria; but incidence of urolithiasis seemed to be less affected by a decrease in the glomerular filtration rate. Hyperuricemia alone had no deleterious effect on renal function as evidenced by follow-up studies over periods up to 12 years. Deterioration of renal function was largely associated with aging, renal vascular disease, renal calculi with pyelonephritis or independently occurring nephropathy. In only very few instances was diminished renal function ascribable to gout alone.

Adult↗
PubMedDate not supplied

Rheumatoid nodulosis: an unusual variant of rheumatoid disease.

A middle-aged man developed multiple subcutaneous nodules associated with palindromic rheumatism. There was little evidence of synovitis; however multiple cyst-like intraosseous radiolucencies were noted. Nodules from two sites were histologically typical rheumatoid nodules. Subjective and objective improvement occurred during penicillamine therapy. This clincial presentation seems sufficiently distinctive to warrant characterization as a variant of rheumatoid disease termed by us: rheumatoid nodulosis.

Arthritis↗