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Biomedical subjects

J B Coelho

Publications and source records attributed to J B Coelho.

At least 19 recordsLinked to original sources
PubMed1984

Double-blind, placebo-controlled trial of propranolol given once, twice and four times daily in stable angina pectoris: a multicenter study using serial exercise testing.

To determine if propranolol given twice daily (b.i.d.) or once daily (q.d.) was as effective as 4 times daily (q.i.d.) for treatment of stable angina pectoris, 78 patients with exercise-induced ST depression of 1.5 mm were randomized to q.i.d., b.i.d., q.d. and placebo groups. All patients received 5 tablets per day, and propranolol groups received 80, 160 and 320 mg/day on successive weeks. At weekly visits, patients underwent treadmill exercise testing before the 8:00 AM dose and at 2 and 9 hours afterward. Exercise duration (seconds) was significantly improved at the final visit compared with baseline by b.i.d. (120 +/- 36 [mean +/-] standard error of the mean p less than 0.001 n = 18) and q.i.d. (100 +/- 37, p less than 0.01; n = 17) regimens, but not by the q.d. (30 +/- 33; n = 18) and placebo regimens (27 +/- 37; n = 17). There was a significant decrease from baseline in the magnitude of ST depression at the final visit, measured at maximal common exercise duration in b.i.d. (-0.96 +/- 0.20 mm, p less than 0.001), q.i.d. (-0.84 +/- 0.20 mm, p less than 0.01) and q.d. (-0.58 +/- 0.18 mm, p less than 0.05) groups, but not in the placebo group (0.03 +/- 0.2 mm). Hourly heart rate by Holter was reduced in all 3 propranolol groups; however, the mean serum propranolol level was significantly lower just before the first dose with q.d. group (56 +/- 20 ng/ml) compared with b.i.d. and q.i.d. groups (146 +/- 22 and 119 +/- 28 ng/ml) with 320 mg/day (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Dynamics of propranolol dosing schedules.

Kinetic and dynamic data from 27 healthy male subjects were evaluated in a double-blind, randomized, double-crossover study to test the hypothesis that 180 mg/day propranolol twice and three times a day would provide much the same plasma levels and beta 1-blockade. The data indicate that propranolol twice rather than three times a day should be favored when beta 1-blockade is needed in therapy. The dynamic efficacy of the two schedules was the same and maximum concentration, AUC0-24, and 0-hr plasma propranolol values were higher after twice-than after three-times-daily dosing. The degree of beta 1-blockade (reduction in exercise tachycardia) was much the same on both dosing regimens at trough concentrations. These data indicate that both twice- and three-times-a-day dosing schedules provide well-sustained 24-hr beta-blockade and are probably interchangeable for therapeutic purposes.

Adult↗
PubMed1977

Heterogeneity of intracortical peritubular plasma flow in the rat kidney.

The 86 Rb-accumulation technique was adapted to the study of intracortical peritubule plasma flow patterns in the rat kidney. A rapid intravenous bolus of 86Rb (50 micronCi) was given to anesthetized nondiuretic rats. One kidney pedicle was tied at 6 s, the other at 12 s. In group I (1o rats) [3H]PAH clearance was measured prior to the 86Rb bolus. In group II (six rats) 86Rb and [3H]PAH (100 micronCi) were given together. The kidneys were snap-frozen, then sliced at -6 degrees C. There were no differences in renal plasma flow (RPF) as measured by either tracer in either group, no differences in the intracortical distribution of [3H]PAH and 86Rb, and no changes in the 86Rb distribution between 6 and 12 s. Tissue plasma flow (TPF) as measured by 86Rb in ml/min per g was 3.88 +/- 0.22 (SE) (142% of RPF/g kidney wt) for cortex 1 (outermost), 3.90 +/- 0.21 for cortex 2, 3.26 +/- 0.14 for cortex 3 (P less than 0.025), 2.17 for cortex 4 (P less than 0.001), 1.34 for cortex-medulla junction (P less than 0.001), and 0.88 +/- 0.07 for outer stripe (P less than 0.001). Peritubular capillary plasma flow, derived as TPF minus GRF/g in each slice, fell progressively from cortex 1 to outer stripe. This is thought to represent lower perfusion rate of "medullary rays."

Animals↗
PubMed1976

Effect of diuresis and nephron dimensional heterogeneity on the distribution of nephron filtration rates.

Conflicting data in studies of the effect of natriuresis on intrarenal single nephron glomerular filtration rate (SNGFR) redistribution may arise from the interplay of hitherto largely overlooked factors. In the present work, the effect of diuresis induced by saline, glucose or mannitol, as well as the effect of anatomical nephron heterogeneity, were studied. A highly significant positive correlation was found between the logarithm of the urine flow per gram of kidney weight (log V) and the mean superficial (S) to mean juxtamedullary (JM) SNGFR ratio. The rise in S/JM SNGFR with diuresis was primarily a function of decreased JM SNGFR. Total proximal tubular length (TPL) was used as a measure of nephron size. The distribution of nephron sizes was evaluated as S/JM TPL. The effects of urine flow and anatomical heterogeneity on S/JM SNGFR were spearated by means of multiple regression analysis, which yielded the following equation: S/JM SNGFR = -0.049 + 0.179 log V + 0.818 S/JM TPL. Both slopes were highly significant (P less than 0.001). These findings indicate that S/JM SNGFR increases with urine flow, independently of sodium homeostasis, and that anatomical heterogeneity has a marked effect and must, therefore, be controlled. Conflicting data in the literature are harmonized with the present data when appropriate correction can be made for the dimensional factor. There is no evidence that SNGFR redistributions play a role in sodium homeostasis.

Animals↗