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Biomedical subjects

H H Ali

Publications and source records attributed to H H Ali.

At least 55 records · Page 3Linked to original sources
PubMed1983

Evaluation of cumulative properties of three new nondepolarizing neuromuscular blocking drugs BW A444U, atracurium and vecuronium.

Comparative patterns of recovery during successive doses of three new, relatively non-cumulative, intermediate-duration non-depolarizing neuromuscular blocking drugs, BW A444U, atracurium (BW33A) and vecuronium (Org NC 45), were studied in 94 surgical patients during thiopentone in nitrous oxide and oxygen with narcotic anaesthesia. The train-of-four (TOF) pattern of nerve stimulation was used. The spontaneous 5-25% recovery time of the first twitch of TOF showed a statistically significant difference between the initial dose and the fifth incremental dose in the cases of atracurium and vecuronium, but not in the case of BW A444U. The 25-75% recovery times for the final doses were significantly longer than the corresponding times for each drug after the initial doses. The percent TOF ratio at the point of recovery of the first twitch to 95% of the control height was compared for the initial and final doses in a series of doses of each drug. The difference was significant only when the final dose of vecuronium was compared with the initial dose (TOF ratio 79.3 +/- 2.3% v. 64.3 +/- 4.4%; P less than 0.005). Analysis of variance indicates that the TOF ratio at 95% recovery of the first twitch of TOF after the final dose of vecuronium (64.3%) is significantly smaller (P less than 0.001) than that of either BW A444U (78%) or atracurium (84%), indicating that vecuronium appears to show more residual fade and greater cumulative effect after incremental doses than BW A444U or atracurium. The data suggest that the cumulative properties of the new drugs may be ranked as follows: atracurium less than BW A444U less than vecuronium.

Adult↗
PubMed1982

Micronodular adrenal disease: a light and electron microscopic study.

A case of Cushing's syndrome due to micronodular adrenal disease in a 17-year-old girl is presented. The adrenals showed both black and yellow nodules. Histologically the cells contained lipofuschin and either had a clear cytoplasm or an eosinophilic cytoplasm with a prominent nucleus. Lymphocytes were a prominent feature. No cells of the zona reticularis were identified. The cell of origin of these nodules appeared to be from the inner layer of the zona fasciculata. We postulate that the disease is caused by an abnormality in the migration and ultimate destruction of cells from the zona fasciculata to the zona reticularis with a build up of cells at the interface zone.

Adolescent↗
PubMed1982

Clinical pharmacology of atracurium besylate (BW 33A): a new non-depolarizing muscle relaxant.

Atracurium, a new non-depolarizing neuromuscular blocking agent, was studied in 70 patients anesthetized with fentanyl, thiopental, and nitrous oxide-oxygen. The dose found to produce 95% twitch inhibition (ED95) was 0.2 mg/kg. The onset time from injection to maximum depression of twitch was 4.0 minutes at this dose; the duration to 95% recovery was 44.1 minutes. Twice the ED95 dose (0.4 mg/kg) had an onset time of 1.7 minutes and a duration of 63.5 minutes. No cardiovascular effects were observed in this dosage range. At higher doses (0.5 and 0.6 mg/kg) arterial pressure decreased 13% and 20% and heart rate increased 5% and 8%, respectively. Sixteen patients received at least four successive doses of atracurium. No clinically significant cumulative effect could be shown when recovery from 25% to 75% of control twitch height was compared for initial and final doses in the series. Atracurium spontaneously decomposes at physiologic pH via the Hofmann elimination reaction and may also undergo ester hydrolysis independent of plasma cholinesterase. These proposed pathways of inactivation may explain the lack of cumulative effect and the drug's intermediate duration of action. Based on the results of this study, atracurium offers several clinical advantages and should undergo more extensive clinical trials.

Adolescent↗
PubMed1981

Twitch, tetanus and train-of-four as indices of recovery from nondepolarizing neuromuscular blockade.

This study was undertaken to compare the sensitivities of the train-of-four response (2 Hz for 2 s), the single twitch (0.15 Hz), and the tetanic response (50 Hz for 5 s) as indices of residual nondepolarizing block. Spontaneous or induced recovery of evoked thumb adduction in response to ulnar nerve stimulation was studied. One hundred and seven adult surgical patients were divided according to the relaxant used, into six groups. We found that when the single twitch recovered to control height, the train-of-four ratio was well below 1.0. This ratio was significantly lower during spontaneous recovery than following neostigmine antagonism of the block (P less than 0.01). The tetanic response was fully sustained when the train-of-four ratio was above 0.7. When the ratio was less than 0.7, variable degrees of fade of tetanus were evident. Analysis of variance indicated similar train-of-four ratios among the six groups at complete recovery of the single twitch irrespective of the relaxant technique used (P less than 0.1). It is concluded that a train-of-four ratio of 0.7 or higher reliably indicates the recovery of the single twitch to control height and a sustained response to tetanic stimulation at 50 Hz for 5 s. The clinical significance of this study is as follows: the train-of-four response provides the same indication of clinical recovery from nondepolarizing block as obtained from tetanic stimulation at a physiological frequency; and reliance on the recovery of the single twitch to control height as a criterion of spontaneous return to normal clinical neuromuscular function may be misleading.

Electric Stimulation↗
PubMed1981

Combination of pancuronium and metocurine: neuromuscular and hemodynamic advantages over pancuronium alone.

Combination of pancuronium and metocurine or pancuronium and d-tubocurarine produces potentiation of neuromuscular blocking effects such that administration of relatively small doses of these drugs can yield clinically effective neuromuscular blockade. The clinical characteristics of the block produced in A.S.A. class I-II patients during N2O-narcotic-thiopental anesthesia by the pancuronium-metocurine combination at the calculated ED95 (N = 8) and at twice the ED95 (N = 9) were compared with the block produced by pancuronium alone at its ED95 (N = 20) and at twice the ED95 (N = 6). Onset time (from drug injection to 95% twitch suppression) and the maximum twitch depression achieved were comparable between corresponding groups, but the 25% recovery time (from drug injection to 25% recovery of twitch height) was significantly shorter in the groups that received the pancuronium-metocurine combination. Furthermore, at twice the ED95, heart rate increased significantly more in the pancuronium group than in the pancuronium-metocurine combination group. Mean systemic blood pressure did not change significantly in either group. We conclude that patients given a combination of pancuronium and metocurine in large doses experience less hemodynamic change and more rapid recovery of neuromuscular function than do patients given equivalent doses of pancuronium alone.

Blood Pressure↗
PubMed1980

The parathyroid in chronic renal failure-- a light and electron microscopical study.

The parathyroids from ten consecutive cases of chronic renal failure coming to operation in a period of seven years were studied by light and electron microscopy. The clinical and biochemical data as well as the levels of immunoreactive parathormone (iPTH) were reviewed. For the sake of comparison adenomata from two cases of primary hyperparathyroidism were studied. In the cases of chronic ;renal failure there were six cases of tertiary hyperparathyroidism with adenoma formation, surrounded by dense fibrous tissue and compression of adjacent parathyroid cell amidst a background of hyperplasia. Two cases showed secondary parathyroid hyperplasia and the remaining two cases were adenomata which clinically affected only one gland. Neither the biochemical data nor levels of iPTH allowed the cases with secondary hyperplasia to be separated from those with tertiary hyperparathyroidism. Similarly electron microscopy showed no distinct differences between these two groups of adenomata from cases of primary hyperparathyroidism. The diagnosis of tertiary hyperparathyroidism is made on a combination of clinical, biochemical and histological features, the histological features being most important. It is concluded that tertiary hyperparathyroidism is part of a histological spectrum in response to chronic renal failure and autonomous glands are related to the mass of parathyroid tissue present.

Adenoma↗
PubMed1980

Stimulus frequency and dose-respone curve to d-tubocurarine in man.

The relationship of the frequency of motor-nerve stimulation to the dose--response to d-tubocurarine was studied in 45 adult patients during nitrous oxide--oxygen--morphine--thiopental anesthesia. One of five stimulus frequencies, 0.1, 0.15, 0.25, 0.5, and 1.0 Hz, was employed in each of five groups of nine patients. Cumulative dose-response curves for inhibition of evoked thumb adduction were constructed at each frequency on log probit scales and the ED50 and ED95 values were determined. The apparent potencies of d-tubocurarine at 0.5 and1.0 Hz were significantly different from that at 0.1 Hz; for example, at 0.1 Hz the ED50 and ED95 were 0.25 and 0.52 mg/kg, respectively. The corresponding values at 1.0 Hz were 0.07 and 0.15 mg/kg, respectively, or approximately 3.5 times less. The durations of recoveries of the twitch from 5--25 per cent of control at 1.0 and 0.5 Hz were 13 +/- 2 min (mean +/- SE) and 20 +/- 2 min, respectively. These durations were significantly different from that at 0.1 Hz (30 +/- 2 min). These results emphasize the importance of defining the stimulus frequency for meaningful interpretation of the dose--response relationships for nondepolarizing relaxants in man. Slow stimulus rates (0.1--0.15 Hz) are most useful clinically, since all levels of clinical relaxation can be achieved at these rates without abolishing the evoked twitch response.

Adult↗
PubMed1980

Clinical characteristics of long-term succinylcholine neuromuscular blockade during balanced anesthesia.

Thumb adductor twitch response to train-of-four (2 Hz for 2 seconds) stimulation of the ulnar nerve was used to assess the clinical characteristics of long-term neuromuscular blockade induced with continuous infusion of succinylcholine during balanced (N2O-O2-narcotic-thiopental) anesthesia. Twitch depression of 80 to 90% was maintained for 86 to 365 minutes by continuous infusion of succinylcholine at 86 +/- 5(SEM) micrograms/kg/min. Of 32 patients, 24 developed phase II block, defined as a train-of-four ratio of less than 50%. There was a large degree of individual variability in sensitivity to development of phase II block. This precluded defining a narrow dose range where transition from phase I to phase II occurred. Tachyphylaxis occurred in 25% of patients and was independent of the type of block. Neither dose nor duration of infusion was predictive of spontaneous recovery rate from phase II block. Of 24 patients who developed phase II block, 50% recovered spontaneously at a rate comparable to the recovery rate from a phase I block. The other 50% manifested prolonged recovery of neuromuscular function. After observing spontaneous recovery in these patients for 31 +/- 5(SEM) minutes, successful antagonism of residual phase II block with anticholinesterase agents was achieved.

Adult↗
PubMed1980

Potentiation of neuromuscular blockade in man produced by combinations of pancuronium and metocurine or pancuronium and d-tubocurarine.

Simultaneous administration of combinations of pancuronium, metocurine, and d-tubocurarine (dTc) were given to A.S.A. class I-II surgical patients during N2O-narcotic-thiopental anesthesia to determine the degree of neuromuscular blockade produced. The pancuronium-metocurine and the pancuronium-dTc combinations were each significantly more potent (p < 0.05) than the additive effects of each of the individual drugs given alone. This greater than additive neuromuscular blocking effect was not seen with the metocurine-dTc combination. Despite the potentiation of neuromuscular blocking intensity by the pancuronium-metocurine and the pancuronium-dTc combination, the duration of blockade was not prolonged. Possibly, such potentiation of neuromuscular blockade might be attributed to simultaneous pre- and postjunctional receptor inhibition. Additional mechanisms might involve augmented conformational attachment to pre- and postjunctional cholinergic receptors or altered protein binding such that a greater than expected proportion of unbound drug reaches its neuromuscular site of activity. Regardless of mechanism, combining pancuronium with dTc or with metocurine can provide surgical relaxation or ideal conditions for endotracheal intubation with smaller amounts of each drug than would be anticipated if their effects were simply additive.

Dose-Response Relationship, Drug↗