Biomedical subjects
Publications and source records attributed to C D Quentin.
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Thirty-eight patients with refractory supraventricular and ventricular tachyarrhythmias were administered a mean oral dosage of 400 mg amiodarone daily (200-600 mg). A high-pressure liquid chromatography method was used to measure serum concentrations of amiodarone and its metabolite desethylamiodarone after one week, one month, three months, and then at 6-month intervals. In 24 patients subcutaneous fatty tissue concentrations were also measured. The mean follow-up was 9 months (4 days to 29 months). A linear correlation was found between amiodarone and its metabolite in serum (r = 0.56, p less than 0.001) as well as in subcutaneous fatty tissue (r = 0.67, p less than 0.001). While serum concentrations were dose dependent, tissue concentrations accumulated during chronic therapy (p less than 0.01, both). Clinical efficacy was achieved in 84% of the patients. No statistically significant difference was found between responders and non-responders as regards serum and subcutaneous fatty tissue concentrations. Side effects of amiodarone occurred in 63%. The incidence of adverse effects was related to significantly higher serum and subcutaneous fatty tissue concentrations of amiodarone and its metabolite (p less than 0.001, both). Thus, although the determination of serum and subcutaneous fatty tissue concentrations does not seem to be helpful for assessing clinical efficacy of this antiarrhythmic drug, these values may predict the occurrence of adverse effects.
With Cyclosporin, a recently developed immunosuppressant drug, the authors treated eight patients with noninfectious chronic uveitis: intermediate uveitis (4), Behcet's disease (2), chorioiditis (1), and anterior uveitis (1). Therapy had to be discontinued in six patients who responded poorly or manifested severe side effects. In four cases the Cyclosporin concentration in the aqueous humor was determined. In spite of a concentration of about 900 ng/ml there was a deterioration in two cases with intermediate uveitis and Behcet's disease. Only one of the eight patients with intermediate uveitis responded well without any recurrence.
A randomized prospective double-blind trial with topical acyclovir (ACV) versus trifluorothymidine (TFT) was performed in the treatment of stromal keratitis. Resolution occurred in only one case (ACV). In all other cases the disease progressed, so that antiviral therapy was discontinued.
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The penetration of cefotaxime, a new semi-synthetic cephalosporin, into human aqueous humour was investigated. Doses of 1 g (17 patients) and 2 g (19 patients) were administered intravenously at time intervals varying from 45 min to 4 h prior to routine cataract surgery. After the 2 g dosage the average concentration of cefotaxime in the aqueous humour was higher (P less than 0.05) and lasted longer than after the 1 g dosage. The highest average concentration in the aqueous humour after the 1 g dosage was 1.85 microgram/ml, 3.95 micrograms/ml after the 2 g dosage. Therapeutic levels were consistently found in both groups for the organisms most commonly responsible for bacterial endophthalmitis, except for Pseudomonas aeruginosa and Staphylococcus epidermidis.
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Following 30-min intermittent post-tetanic potentiation of monosynaptic reflexes in the ventral horn of the spinal cord of 10 cats, the amino acid composition was analyzed after reacting with 14C-dansylchloride and by two-dimensional chromatography. The amino acids in comparable segments of the spinal cord from eight animals after ether anesthesia and from five animals who were operated on but not stimulated were also analyzed. In the latter the operation itself influenced the amino acid composition as compared to those animals who were anesthetized. Comparison between the different control groups showed that the operated animals can be used as a control for calculation of the changes caused by potentiation. The amino acids glycine, glutamic acid and aspartic acid, which act as either inhibitory or excitatory neurotransmitters, increased significantly after potentiation, as did the amino acids lysine, histidine, leucine, isoleucine, and proline.
In order to determine the chemical changes which might occur during post-tetanic potentiation, amino acids from the motor regions of the ventral horn of the spinal cord (potentiated and unpotentiated sides) of 10 different cats were analyzed. The intermittent tetanic stimulation of the Nn. gastroc. (only on the potentiated side) was carried out until a maximum of potentiation was reached (3--4 min). The monosynaptic reflexes were obtained from the ventral roots (L7 or S1) of both sides. The amino acids of the potentiated side were compared to those of the unpotentiated side (control) using a 14-C-dansyl chloride procedure. The two main amino acids considered to be excitatory neurotransmitters, glutamic acid and aspartic acid, showed a more than 20 per cent increase on the potentiated side as compared to the control side. Glycine, which plays an inhibitory role, especially in the spinal cord, reacted with 6 per cent decrease, whereas GABA which is also considered as an inhibitory neurotransmitter showed a change of + 11 per cent on the potentiated side as compared to the unpotentiated side. The importance of the potentiation time for those changes is pointed out.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.