Biomedical subjects
L A Katz
Publications and source records attributed to L A Katz.
What is a paradigm and when does it shift?
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Combined alpha/beta-blockade versus beta 1-selective blockade in essential hypertension in black and white patients.
The purpose of this multicenter investigation was to determine the efficacy and safety of the alpha/beta-blocker labetalol versus the beta 1-selective beta-blocker atenolol in white and black patients with essential hypertension. Equal numbers of black and white patients were enlisted to form four treatment groups (white patients taking either labetalol or atenolol and black patients taking either labetalol or atenolol). Two hundred ninety-two patients (152 white and 140 black patients) with essential hypertension characterized by a standing diastolic blood pressure of 105 to 119 mm Hg (inclusive) were recruited for this trial. Patients were randomized to either labetalol (dosage titrated from 200 to 1600 mg/day) or atenolol (dosage titrated from 50 to 100 mg/day). The therapeutic goal was achievement of a standing diastolic blood pressure of 90 mm Hg or less or a fall of 15 mm Hg in diastolic pressure from baseline value at the end of the placebo run in period. At the end of the study there were no significant differences in blood pressure or heart rate changes in the supine position between the labetalol and atenolol groups. In contrast, labetalol produced greater reduction in both the standing systolic and diastolic blood pressure (-12/-13 mm Hg, respectively) compared with atenolol (-7/-9 mm Hg; p less than 0.05; p less than 0.005, respectively). The greatest decrease in blood pressure was observed in white patients receiving labetalol. In black patients the decrease in blood pressure was greater in those treated with labetalol compared with atenolol, particularly with respect to the systolic blood pressure. We conclude that the alpha 1-blocking property of labetalol provides an additional lowering of the blood pressure over that seen with beta 1-blockade alone, especially in the standing position, and this enhanced efficacy is not confined to one radical group.
Multicenter trial of L-carnitine in maintenance hemodialysis patients. I. Carnitine concentrations and lipid effects.
Previous studies have reported conflicting results of carnitine supplementation on plasma lipids in patients with chronic renal failure. We therefore performed a four center, double-blind placebo controlled trial to evaluate the effects of post-hemodialysis intravenous injection of L-carnitine in ESRD patients on maintenance hemodialysis. Thirty-eight patients received up to six months of L-carnitine infusions (20 mg/kg) post-dialysis and 44 patients received placebo infusions. In both groups of patients, baseline pre-dialysis plasma and red blood cell total carnitine levels were normal, but pre-dialysis plasma-free carnitine concentrations and free/total ratios were subnormal, and plasma acyl levels were elevated. Post-dialysis plasma free and total carnitine concentrations were also subnormal. Plasma and red blood cell total carnitine levels rose eightfold in carnitine recipients, but were unchanged from baseline in those receiving placebo. There were no significant changes observed in plasma triglycerides, HDL-cholesterol or other lipoprotein parameters in either the carnitine or placebo treated groups. We conclude that carnitine metabolism is altered in uremia. Furthermore, in a randomly-selected hemodialysis population, L-carnitine injection at the dose of 20 mg/kg results in significant increases in blood (and perhaps tissue) carnitine levels, but this is not associated with any major effects on lipid profiles.
Multicenter trial of L-carnitine in maintenance hemodialysis patients. II. Clinical and biochemical effects.
Since carnitine deficiency has been reported in some patients undergoing maintenance hemodialysis, we studied the effects of intravenous infusion of L-carnitine or placebo at the end of each dialysis treatment. The trial, which lasted seven months (one month baseline, 6 months treatment) was multicenter, double blind, placebo controlled, and randomized. Eighty-two long-term hemodialysis patients, who were given either carnitine (N = 38) or placebo (N = 44), completed this study. In each group, clinical and biochemical parameters during treatment were compared with baseline values. Intra-dialytic hypotension and muscle cramps were reduced only in the carnitine treated group, while improvement in post-dialysis asthenia was noticed in both carnitine and placebo groups. Maximal oxygen consumption, measured during a progressive work exercise test, improved significantly in the carnitine group (111 +/- 50 ml/min. P less than 0.03) and was unchanged in the placebo group. L-carnitine treatment was associated with a significant drop in pre-dialysis concentrations of serum urea nitrogen, creatinine and phosphorus (means +/- SEM, 101 +/- 4.5 to 84 +/- 3.9, 16.7 +/- 0.67 to 14.7 +/- 0.64, and 6.4 +/- 0.3 to 5.5 +/- 0.4 mg/dl, respectively, P less than 0.004). No significant changes in any of these variables were noticed in the placebo group. Mid-arm circumference and triceps skinfold thickness were measured in 11 carnitine and 13 placebo treated patients. Calculated mid-arm muscle area increased in the carnitine patients (41.37 +/- 2.68 to 45.6 +/- 2.82 cm2, P = 0.05) and remained unchanged in the placebo patients.(ABSTRACT TRUNCATED AT 250 WORDS)
The mechanism of respiratory control in the in vivo heart.
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The hierarchical structure of geriatric patient satisfaction. An Older Patient Satisfaction Scale designed for HMOs.
This paper describes an instrument design effort aimed at measuring patient-satisfaction among older (65 years and over) subscribers of HMOs. The study was conducted in a multi-satellite prepaid group practice in Buffalo, New York. In order to be able to construct a satisfaction measure that would reflect the interests of the actual consumers of HMO-services, a series of four focused group interviews were held with 24 randomly selected elderly enrollees. The substantive content of these interviews was systematically analyzed for both topics and ideas, yielding a total of 173 distinct ideas about the perceived satisfaction with the services received expressed over 3,176 lines of narrative. From this substantive pool, sixty attitudinal statements were constructed with the ideas represented in these statements being proportional to the number of lines of transcribed discussion devoted to each topic. This 60-item Older Patient Satisfaction Scale (OPSS) was submitted to a systematic sample of 229 elderly HMO subscribers. They also were asked to complete two existing scales: the Ware PSQ, and the Larsen CSQ-8. Factor analysis performed on the OPSS-items yielded 14 primary factors of geriatric patient satisfaction, two second-order and one third order general factor. As the second-order factors accounted for the largest proportion of the common variance, those items of the original 60-item OPSS were identified that had highest loadings on these second-order factors, yielding 7 such items for one and 5 for the other. These scales had alpha-reliabilities of .83 and .80, respectively. It was also found that the OPSS had good convergent validity with the PSQ and CSQ-8. The overall psychometric properties identified for the OPSS, as well as the fact that it was constructed from a health-care consumer's perspective, makes it well suited for use with a unique and rapidly expanding geriatric patient population.
Relation between phosphate metabolites and oxygen consumption of heart in vivo.
The relation between induced increases in cardiac work and phosphate metabolites was investigated in the canine heart in vivo to evaluate the role of ATP hydrolysis products, ADP and inorganic phosphate (Pi), in the control of myocardial oxygen consumption (MVO2). In these studies, myocardial blood flow and oxygen consumption were simultaneously measured with the 31P-nuclear magnetic resonance (NMR)-detected phosphate metabolites. Three protocols were used to increase myocardial work: pacing, epinephrine, and phenylephrine infusions. When these protocols were used, no or only slight changes in myocardial ATP, Pi, and creatine phosphate were observed with a greater than threefold increase in MVO2. The calculated intracellular free Mg concentration, ADP, and pH were also only slightly affected by these increases in work. These data indicate that a simple model involving the feedback of cytosolic ADP and Pi to the mitochondria regulating respiration is inadequate to explain respiratory control in vivo. These data suggest that some other parameters or cooperativity effects involving the phosphate metabolites must play a role in the feedback between respiration and work in the heart in vivo.
Activation of dehydrogenase activity and cardiac respiration: a 31P-NMR study.
31P-NMR studies were performed to determine the tissue phosphate and oxygen consumption effects of known maneuvers on the activation of pyruvate dehydrogenase during work jumps in the perfused rat heart. In control studies of the glucose-perfused heart, work jumps, with pacing, resulted in a 32% increase in oxygen consumption (QO2) from 1.72 +/- 0.09 to 2.29 +/- 0.12 mmol O2.h-1.g dry wt-1. During this transition no significant change in the high energy phosphates were detected. In contrast, work jumps did cause changes in the phosphates when the activation of pyruvate dehydrogenase was blocked with 2.5 micrograms of ruthenium red per milliliter or maximally stimulated with 11 mM pyruvate before the increase in work. The observed increase in QO2 and inorganic phosphate and calculated increase in ADP are consistent with these phosphates controlling mitochondrial respiration under these conditions. These results suggest that the activation of pyruvate dehydrogenase and/or other dehydrogenases may be an important step in the orchestration of work and QO2.
Life-threatening enterocolitis after gold salt therapy.
Two patients developed life-threatening enterocolitis after receiving gold salt therapy. This disorder is attended by a mortality rate of 50% but the intestinal lesion appears to be reversible. The mechanism of the drug toxicity is not known. The course may be fulminant and recovery may occur only after many weeks. Total bowel rest, nasogastric suction, total parenteral nutrition with supplemental colloid and careful monitoring of fluid and electrolyte balance may improve survival.
Microsomal antibody and circulating immune complexes in allergic gastroenteropathy.
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