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Biomedical subjects

L Martinez

Publications and source records attributed to L Martinez.

At least 127 records · Page 7Linked to original sources
PubMed1972

Interactions between amino acid transport systems in Neurospora crassa.

Mutants of Neurospora crassa, selected as resistant to l-canavanine and l-thialysine, are partially deficient in the uptake of basic amino acids. Neutral amino acids completely inhibit uptake of basic amino acids, and this inhibition is dependent on the activity of a neutral amino acid permease. In contradistinction, mutants resistant to 4-methyl-dl-tryptophan are partially deficient in the uptake of neutral amino acids. Basic amino acids completely inhibit neutral amino acid uptake, and this inhibition is dependent on the activity of a basic amino acid permease. It is proposed that these specific transport systems compete with a general amino acid permease for some common element. The general permease is also regulated by ammonia, the amino acid pool, or both. The activity of the general permease can be eliminated phenotypically by a high concentration of glycerol or a high temperature. It is also shown that l-citrulline is transported by the neutral amino acid permease and by the general amino acid permease.

Amino Acids↗
PubMed1968

Liver shunts.

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Angiography↗
PubMedDate not supplied

Single and multiple dose pharmacokinetics of sultosilic acid in humans.

Single and multiple oral doses of Sultosilic acid were administered to four healthy volunteers. Plasma and Urine levels of unchanged Sultosilic acid (I) and its major metabolite (II) were measured. I and II were extracted from plasma and urine with chloroform after ion-pair formation and analysed by HPLC using a U.V. detector. Sultosilic acid was well absorbed and the plasma concentrations declined bioexponentially with mean half-lives of 1.9 h (fast disappearance phase, alpha) and 17.6 h (slow disappearance phase, beta) for I and 2.0 h (alpha) and 17.0 h (beta) for II. Renal clearances of I and II were 50.5 ml/min and 74.8 ml/min respectively. 60% of the administered dose was excreted in urine, 28% unchanged (I), the remainder as carboxylic derivative (II). Minimal drug concentrations in plasma in the range of those detected in steady state conditions were already found within the first day of treatment.

Adult↗
PubMedDate not supplied

Single and multiple dose pharmacokinetics of a new NSAID (droxicam) in healthy volunteers.

The pharmacokinetics of droxicam, both as a single 10 mg dose and as a multidose regimen of 10 mg/day for 20 consecutive days, have been studied in healthy volunteers. The study was performed in two separate groups of volunteers. Following a single dose the Cmax was 0.82 +/- 0.15 micrograms/ml, the Tmax was achieved at 6.1 +/- 3.5 h, the elimination half life was 65.7 +/- 17.6 h, the Clt/F was 2.04 +/- 0.53 ml/min, the Vd/F was 11.0 +/- 1.7 l and the AUC infinity was 86.9 +/- 24.6 mugh/ml, which was similar to results reported in other study from piroxicam (10 mg). Following multiple doses the Cmed(ss) was 2.06 +/- 0.42 microgram/ml, the Tmax(ss) was 8.2 +/- 6.0 h, the elimination half life was 41.4 +/- 12.4 h, the Clt/F was 3.30 +/- 0.63 ml/min, the Vd/F was 11.8 +/- 4.3 l and the AUC infinity was 52.4 +/- 11.3 mugh/ml. The differences encountered between single and multiple dose administration in elimination kinetics are due to the wide interpersonal variation described for the elimination half life of piroxicam. It may be concluded from these results that absorption, elimination and bioavailability kinetics of droxicam are independent of the administered dose.

Administration, Oral↗
PubMedDate not supplied

Cross-over study of the bioavailability of a new NSAID (droxicam) versus piroxicam in healthy volunteers following single and multiple dose administration.

Droxicam is a new anti-inflammatory drug which is a pro-drug of piroxicam and possesses delayed absorption kinetics. In this study, the comparative bioavailability of the two compounds was investigated. The study was performed following a cross-over design with single (20 mg) and multiple (20 mg/day for 30 consecutive days) administration in 25 healthy volunteers. The peak plasma concentrations of piroxicam, obtained following administration of droxicam, were lower than those calculated for administration of piroxicam, and the time taken to reach these peak concentrations was increased by approximately 5-7 h. There was no significant difference in either the elimination kinetics of piroxicam or the AUC values found following administration of the two products. Bioavailability of droxicam is equal to that of piroxicam, with a slower rate of absorption.

Administration, Oral↗
PubMedDate not supplied

Chromium toxic effect monitoring using ozonation method.

The hexavalent chromium toxicity (in vitro) to plasma, erythrocytes, and semen lipids was evaluated. The ozonation technique is suggested to realize the rapid measurements of the lipid peroxidation (LPO) by means of the double bond indexes (DB-index and DB(cell)-index) calculation. The obtained experimental results permit to conclude that it is possible to detect the chromium effect on LPO by ozonation. The DB-index and DB(cell)-index determination in the plasma, erythrocytes, and sperm can be considered as a measure of this effect. Ozonation, suggested in this work, can provide the useful preliminary information for specialists and is a quantitative, fast, inexpensive, and simple method. In view of these comments, we conclude that the suggested ozonation method can be considered as the acceptable modern technique for the chromium toxic effect monitoring in vitro.

Adolescent↗