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Biomedical subjects

C Simon

Publications and source records attributed to C Simon.

At least 361 records · Page 20Linked to original sources

[Minocycline in the treatment of respiratory tract infections (author's transl)].

Minocycline concentrations in serum, saliva, sputum, pleural exudate and lung extracts after a single dose of 0.2 g (orally or intravenously) were measured on 32 patients with bronchial or lung disease. On the first day of treatment, concentrations in purulent sputum were five to ten times higher than in mucous sputum and saliva, after two hours they were one third, after three hours half the serum concentration (0.7 and 1.0 microgram/ml, respectively). After six hours the concentration was the same (1.6 microgram/ml). On the third day of treatment (after 0.2 g every 24 hours) concentrations in purulent sputum were higher than on the first day by 0.8 microgram/ml (after two hours) and by 0.95 microgram/ml (after three hours). After one-hour i.v. infusion of 0.2 g minocycline concentrations in mucous sputum and saliva rose more quickly on the first day than after oral administration. On the third day of treatment (after 0.1 g orally every 12 hours) pleural exudate level was almost as high as serum level. Minocycline concentration in lung extract on the third day of treatment--four, five and ten hours after the last dose--was 0.4 and 0.8 microgram/g, respectively (while serum concentration at the same time was 1.0-1.5 microgram/ml).

Humans↗

On the use of comfortable listening levels in speech experiments.

In order to investigate the effect of presentation subjects' labeling of speechlike sound patterns, synthetic stimuli were constructed, varying systematically FO contours, VOT, and F2 transitions. These stimuli were presented in random sequences at levels between 15 and 105 dB SPL to subjects with normal hearing. No significant response variation was observed in the range 40--100 dB SPL. Subjects' labeling behavior suddenly breaks down below levels of around 35 dB SPL. The secondary findings of the study are also discussed in terms of different specific processing strategies for different specific speech features.

Auditory Threshold↗

[Multiple hepatic cysts in rat rendered diabetic by streptozotocin and treated by islets of Langerhans grafts: the role of streptozotocin].

This study is based on the investigation by light and electron microscopy of hepatic biopsies from 14 rats rendered diabetic by streptozotocin and treated by portal embolization of islets of Langerhans. Macroscopically, voluminous projecting cysts were observed, sometimes occupying a whole lobe. By light microscopy, the cysts were lined with canalicular-type epithelium. Ultrastructural studies confirmed the canalicular nature of these cells and cilia were frequently observed. The presence of identical cysts in rats rendered diabetic by streptozotocin but not treated by embolization proves that this product is the agent responsible for the induction of this adenomatosis.

Animals↗

Absorption of bacampicillin and ampicillin and penetration into body fluids (skin blister fluid, saliva, tears) in healthy volunteers.

Equimolar doses of bacampicillin, which is rapidly converted to ampicillin in the body by hydrolysis, and ampicillin were administered orally, in the case of ampicillin also by intravenous injection, to 10 healthy subjects (cross-over study). Comparison of the areas under the serum concentrations curves after intravenous and oral administration showed that bacampillin was absorbed to 95% and orally given ampicillin to 35%. The mean peak serum levels (Cmax) after 0.8 g of oral bacampicillin were higher (15.9 microgram/ml) and appeared earlier (tmax 60 min) than after 0.556 g of oral ampicillin (3.2 microgram/ml, tmax 150 min). One and three hours after oral administration skin blister fluid contained four times more ampicillin after doses of bacampicillin than after oral ampicillin. One hour after intravenous injection of ampicillin the skin blister concentrations were 20 times higher than after oral administration of this antibiotic and three to four times higher than after oral administration of bacampicillin. The levels in saliva and tears were also determined and showed similar relationships. Since higher peaks serum levels resulted in higher and longer lasting concentrations in the extravascular space, bacampicillin is to be preferred for oral therapy.

Absorption↗

Sisomicin: in vitro activity and pharmacokinetics.

In vitro activity of sisomicin and gentamicin was compared in serial dilution tests for 619 bacterial strains (Staphylococcus aureus, E. coli, Proteus mirabilis, Proteus vulgaris, Enterobacter, Klebsiella, Pseudomonas aeruginosa, Salmonella, Serratia marcescens). Mean MIC of sisomicin was lower by one geometrical dilution step compared with gentamicin for Pseudomonas, Proteus vulgaris, Klebsiella, and Serratia, while it was almost identical with the other species. Resistance (MIC greater than 5 microgram/ml) against sisomicin was observed in 2% of Pseudomonas strains, resistance against gentamicin in 8%. Ten healthy adult volunteers had serum peak levels (after i,m. injection of 40 mg and 80 mg sisomicin) of 2.7 and 3.2 microgram/ml. Urine recovery (in 24 hrs) was 76%. Continuous i.v. infusion of sisomicin or gentamicin (6.6 mg/hour in 7 healthy adult volunteers) yielded in serum levels of 0.64 and 1.03 microgram/ml respectively. Biological half-life (90 minutes), urine recovery (60% in the fourth hour), renal clearance and skin blister levels at the end of infusion were almost identical for both antibiotics; total clearance was somewhat higher with sisomicin than with gentamicin.

Adult↗

Long-term turnover of thyroid iodine in the rat as studied by the isotopic equilibrium method.

A long-term kinetics study was made in rats in a steady state for iodine metabolism and receiving either 5 microng iodine (group5) or 50 microng iodine (group 50) daily. By using the isotopic equilibrium method, the value of the renewed fraction was followed during at least 120 days in the thyroglobulin (Tg) and the lysosomes of the thyroid and in the plasma hormones. For both groups, only part of the total iodine pool in the Tg as well as in the lysosomes is directly available for secretion. Furthermore, the direct precursor pool of iodine for secretion in the lysosomes is dependent on the daily iodine intake (1.3 times greater in group 50 than in group 5) while the Tg iodine supply in the colloid is not (80% of the total Tg iodine pool for both groups). An iodine pool with a very slow turnover is present in the lysosomes (about 50% in each group), in the Tg of group 5 (more than 15%) and probably in the Tg of group 50 (less than 5%). Thus, the distribution of such a pool between lysosomes and Tg is dependent on the daily iodine intake. The very slow iodine pool is probably not accumulated into the follicles, since every studied pool is in steady state. It is practically not secreted since hormones in the plasma are entirely renewed. Again, it is practically not deiodinated since the thyroid iodide pool is also entirely renewed. These three criteria are valuable for both groups. Although one cannot entirely exclude its participation in secretion, it is postulated that the major part of this pool is re-cycled without deiodination. Both lysosome-lysosome and lysosome-colloid pathways of re-cycling have been postulated. The second pathway is supposed to increase when the daily iodine intake is decreased.

Animals↗

[The geriatric pharmacology of cefazolin, cefradin and sulfisomidine].

Clinical pharmacology of 3-(5-methyl-1,3,4-thiadiazol-2-ylthiomethyl)-8-oxo-7-(tetrazol-1-ylacetamido)-5-thia-1-azabicyclo-(4,2,0)oct-2-en-carbonic acid (cefazolin) and D-7-[2-amino-(cyclohexa-1,4-dien-1-yl)-acetamido]-3-methyl-8-oxo-5-thia-1-aza-(4,2,0)-oct-2-ene-2-carbonic acid monohydrate (cefradine) was compared in young and old adults without renal disease after i.v. injection of 1 g. Mean serum levels of cefazolin after 4 h and 6 h were significantly higher in old persons (25.0 and 14.7 mug/ml, resp.) than in young persons (16.2 and 7.8 mug/ml, resp.). Serum concentrations of cefradine after 2 and 4 h were found also higher in the aged (11.2 and 4.4 mug/ml, resp.) than in young adults. Half-life of cefazolin was prolonged from normally 94 min to 189 min, half-life of cefradine from 32 min to 72 min. Skin blister fluid punctured once for antibiotic assay contained less cefazolin in old persons (after 4 and 6 h only 22.4 and 17.4 mug/ml, resp.) than in young persons (32.7 and 27.6 mug/ml, resp.). Cefradine levels in skin blister fluid 0.5 and 1 h after i.v. injection showed also a significant difference (11.4 and 11.9 mug/ml, resp.) in old persons, 17.3 and 16.5 mug/ml, resp., in young persons). Elimination constants (alpha, beta, kel, k12, k21) were always lower in geriatric patients. Renal clearance of cefazolin was reduced from 83 ml/min to 43 ml/min, and renal clearance of cefradine from 378 ml/min to 152 ml/min. After i.v. injection of 1 g 6-sulfanilamido-2,4-dimethyl-pyrimidine (sulfisomidine) total content of the drug in blood was higher in elderly people than in young persons, but proportion of acetylated sulfisomidine was nearly the same in both groups (15%). It is supposed that higher serum levels of some drugs in old persons (over 70 years) can be explained by impaired renal excretion and slower tissue penetration of the compound from the blood.

Adult↗