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Biomedical subjects

A Meisel

Publications and source records attributed to A Meisel.

87 records · Page 5Linked to original sources
PubMed1976

Effect of vasopressin on uric acid excretion: evidence for distal nephron reabsorption of urate in man.

1. When changes in urine flow rate were induced by vasopressin administration in eight subjects, urate excretion decreased by a mean of 14% and was positively correlated with urine flow rate (r = 0.88, P less than 0.01). The effect of vasopressin on urate excretion was not influenced by prior changes in extracellular fluid volume. 2. Mannitol administration in a dose sufficient to prevent vasopressin-induced alterations in urine flow rate blocked the effect of vasopressin on urate excretion. 3. Alterations in urate excretion produced by changes in extracellular fluid volume could be distinguished from the urate-retaining effect of vasopressin-mediated decrease in urine flow. Urate retention after vasopressin was entirely attributed to a decrease in pyrazinamide-suppressible urate excretion, consistent with either decreased secretion or enhanced post-secretory reabsorption of urate. 4. Since diminished urine flow rate in the distal part of the nephron is more likely to lead to enhanced reabsorption of urate, these results provide additional evidence for urate reabsorption in the distal part of the nephron.

Adult↗
PubMed1975

Influence of volume expansion, serum sodium, and fractional excretion of sodium on urate excretion.

The relative contributions of volume expansion and increased fractional excretion of sodium to the uricosuria of saline infusion were assessed in 19 subjects by volume expansion with rapid infusion of 21 of hypertonic saline (3%), isotonic saline (0.9%), or hypotonic saline (0.45%). Urate excretion increased 385 mug/min (P less than 0.01) with hypertonic, 145 mug/min (P less than 0.05) with isotonic saline, and 294 mug/min (P less than 0.001) with hyptonic saline. When 150 meq of sodium chloride was administered as appropriate volumes of hypertonic, isotonic of hypotonic saline, the magnitude or uricosuria was correlated with volume load (r = 0.66, P less than 0.002). fractional excretion of sodium correlated with infusion volumes for all studies taken together (r = 0.35, P greater than 0.1). The relationship between fractional excretion of sodium and fractional excretion of urate was entirely attributed to their correlation with infusion volume. Both post-pyrazinamide urate excretion and pyrazinamide suppressible urate excretion increased with volume expansion.

Adolescent↗
PubMed1975

Hyperuricosuria and increased tubular secretion of urate in sickle cell anemia.

Seven young adults with uric acid overproduction due to sickle cell anemia were normouricemic with a mean serum uric acid level of 4.9 mg/100 ml. Urate clearance was greater in these patients than in normal subjects or in patients with primary hyperuricemia due to uric acid overproduction. The increase in urate clearance was entirely accounted for by increased pyrazinamide suppressible urate clearance. Pyrazinamide administration abolished the uricosuric response to ribonucleic acid (RNA) feeding in these patients with sickle cell anemia, and maximal uricosuric response to the administration of probenecid was similar in the patients with sickle cell anemia and in normal subjects suggesting that reabsorption of both filtered and secreted urate was not impaired in sickle cell disease. Pyrazinamide suppressible urate clearance at maximal uricosuric response to probenecid was increased in patients with sickle cell disease suggesting increased tubular secretion of urate. This increase in urate secretion permits most young adults with urate overproduction due to sickle cell anemia to remain normouricemic and may account for the low frequency of secondary gout in this disease.

Adolescent↗
PubMed1975

Rights of the mentally ill: the gulf between theory and reality.

Within the last few years several lawsuits have significantly increased both the procedural and the substantive rights of mental patients; among them are Lessard v. Schmidt, in which the court held that persons facing involuntary civil commitment are entiltled to dueprocess safeguards, and Wyatt v. Stickney and Donaldson v. O'Connor, concerned with the right ot adequate treatment. The author draws on the problems of implementing the landmark decree of Miranda v. Arizona, guaranteeing the rights of criminal suspects, in discussing the difficulties of translating rights promulgated in the courts into reality. He believes that enofrcement of patients' rights depends not on the law alone but also on the sensitivity and good faith of mental health workers.

Attitude of Health Personnel↗
PubMedDate not supplied

Legal and ethical myths about informed consent.

Informed consent is a foundational concept of medical ethics. Since its enunciation almost 4 decades ago, it has engendered, and continues to engender, a great deal of debate and opposition from practicing physicians. We believe that much of the negative reaction to informed consent stems from some fundamental misunderstandings about what informed consent requires. This article discusses and refutes several myths about informed consent that have acquired some currency among physicians.

Comprehension↗
PubMedDate not supplied

An experimental selection system to identify bacterial cells exhibiting a new DNA host specificity.

Restriction-modification enzymes interact with DNA sequences in a highly specific manner. Mutations within the DNA binding region of the enzymes could be expected to produce enzyme variants with changed DNA sequence specificities. We developed an efficient in vivo selection system that enabled us to detect one cell coding for a restriction-modification system with a new DNA sequence specificity in a background of more than 10(6) cells with the original DNA sequence specificity.

Bacteriophage lambda↗
PubMedDate not supplied

Mutual activation of two restriction endonucleases: interaction of EcoP1 and EcoP15.

Type III restriction endonucleases recognize nonsymmetric nucleotide sequences. A necessary condition for DNA cleavage is the presence of two unmethylated recognition sites which are inversely ('head-to-head') oriented in the DNA double strand. A DNA substrate possessing one EcoP1 and one EcoP15 site in the head-to-head configuration could not be cleaved by the individual enzymes, however, it was specifically digested in the simultaneous presence of both enzymes. In agreement with the tracking-collision model for the DNA interaction of type III enzymes cleavage could be abolished by Lac repressor bound between the two sites. We conclude that two different type III enzymes can functionally cooperate in the cleavage of DNA.

DNA Methylation↗