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Biomedical subjects

R Etienne

Publications and source records attributed to R Etienne.

At least 19 recordsLinked to original sources
PubMed2001

Determination of moxifloxacin in growth media by high-performance liquid chromatography.

A direct injection high-performance liquid chromatographic method with column switching has been developed to determine moxifloxacin in Mueller-Hinton broth. A LiChrocart 4-4 pre-column filled with a LiChrospher 100 RP 18, 5 microm and a 150 x 4.6 mm I.D. column packed with a Supelcozil ABZ+ Plus were used and led to a retention time of 5.70 min. Fluorescence detection allowed one to reach a quantification limit of 0.05 microg/ml with a 100-microl sample size. The standard curves were linear from 0.05 to 3.2 microg/ml. Intra- and inter-day imprecisions within the linearity range were < or =4.76 and < or =5.75%, respectively. The mean relative errors for the same day and the day-to-day inaccuracies ranged from -2.93 to +4.50% and from -1.10 to +6.00%, respectively. The method was demonstrated to be useful for pharmacokinetic-pharmacodynamic studies of moxifloxacin in an in vitro model.

Anti-Infective Agents↗
PubMed2001

New approach for accurate simulation of human pharmacokinetics in an in vitro pharmacodynamic model: application to ciprofloxacin.

An in vitro pharmacodynamic model using a disposable dialyser unit and computer-controlled devices was developed. Feedback control of peristaltic pump flow rates is used to maintain constant flow rates, thus avoiding the problem of the modification of the physical properties of the tubing that generally occurs. Fast equilibrium is obtained with capillaries, which allows simulation of the same kinetic profile in the central and the peripheral compartments. Thus, more accurate simulation of plasma, extracapillary fluid or whole tissue kinetics can be performed. Our model was validated by simulation of a 30 min infusion of a 200 mg dose, and of an oral administration of a 500 mg dose of ciprofloxacin.

Administration, Oral↗
PubMed2001

Mechanisms of urea tolerance in urea-adapted populations of Drosophila melanogaster.

When behavioral avoidance cannot prevent an animal from being exposed to novel environmental toxins, physiological mechanisms must cope with the toxin and its effects. We are investigating the basis of urea tolerance in populations of Drosophila melanogaster that have been selected to survive and develop in food containing 300 mmol l(-1) urea. Previous research has demonstrated that the urea-selected larvae have lower levels of urea in their body than control larvae reared under the same conditions. The current series of experiments focuses on three possible ways of reducing urea levels in the body: urea metabolism, increased urea excretion and decreased urea uptake from the environment. We tested for urea metabolism directly, by assaying for activity of two urea-metabolizing enzymes, and indirectly, by looking for reduced urea content of their medium. To measure urea excretion rates in whole animals, we reared control and urea-selected larvae on urea-containing food (urea food), switched them to normal food and monitored the loss of urea from their hemolymph. We measured urea uptake by rearing control and selected larvae on normal food, switching them to urea food and monitoring the rate of urea appearance in the hemolymph. We found no evidence for urea metabolism by either direct or indirect methods. Control larvae excreted urea at a higher rate than selected, probably because they contained more urea than the selected larvae and thus had a greater gradient for urea loss. The rate of urea uptake in selected larvae was 2 mmol l(-1) h(-1) slower than the rate in control larvae, a difference that could account for the measured differences in body urea levels. Thus the selected larvae appear to have adapted to urea exposure primarily by decreasing the ability of urea to enter their body in the first place. The mechanism responsible for this reduction in uptake is uncertain.

Adaptation, Physiological↗
PubMed1992

[The nurses too].

Explore the source record for details and available documents.

Education, Nursing↗
PubMed1988

Effect of long-term treatment with celiprolol on pulmonary function in a group of mild hypertensive asthmatics.

Previous studies have shown that single dose or short-term administration of celiprolol does not impair pulmonary function in patients with asthma. The long-term effects of celiprolol and chlorthalidone on respiratory function in mild hypertensive asthmatic patients were compared. Following a 1-month placebo washout period, five patients were randomized to 3 months of treatment with celiprolol, and four patients were treated with chlorthalidone. This double-blind study was followed by a 12-month open trial in 13 asthmatics. Forced expiratory volume at the first second of expiration (FEV1) remained unchanged throughout the 12-month treatment period. This finding is of interest since a spontaneous decrease in FEV1 of 20 ml/year has been observed in recent surveys of asthmatic patients. No changes in peak expiratory flow rate or maximum expiratory flow at 50% of vital capacity were observed during the study, but measurements of FEV1 before and 2 h after drug administration indicated that celiprolol had no direct bronchodilating effect. The responsiveness to inhaled salbutamol was unaltered during the 12-month trial period, demonstrating that celiprolol does not block the beta 2-adrenoceptors on bronchial smooth muscle. Our results indicate that celiprolol is a safe long-term treatment for hypertension in asthmatic patients. Nevertheless, a survey of a large number of patients may be useful in order to detect individuals at risk, since sensitivity to beta-blockade may vary between patients.

Adult↗
PubMed1984

[Quantitation of the visual field].

With kinetic perimetry, the visual field chart had the appearance of a geographical map. Since the isopters were not geometric, their surfaces were barely measurable. However, with recent three dimensional computerised (or semi-computerised) perimetry quantitative evaluation of the print-out may easily be done. The visual acuity is expressed by a fraction or ratio. In a similar way our deficit ratio gives a percentage score of visual field volume defects. Using the Peritest, it is very easy to establish the field's deficit ratio. All the defects are classified and have a score. Scores are then added up to establish the deficit ratio. (The same procedure may be used with other perimeters like the Visual Field Analyser). Why express field loss as a deficit ratio? In the natural history of a Primary Open Angle Glaucoma (i.e. a disease of the visual field), the comparison between consecutive visual fields may be difficult. Instead of looking at a collection of print outs, it is easier to look at the numbers of the deficit ratio to appreciate if there is evolution of the disease. In discussions with the patient, it sounds better if the ophthalmologist speaks of a "percentage" of visual field loss: the patient may understand his own situation more easily. Each point is tested twice at each examination to give an idea of patient response fluctuation. Before finding progression of the disease, it is necessary to know the range of an individual's variation in answers. The principle of all sciences is to measure what is measurable, and to render measurable that which is not.

Computers↗
PubMed1983

[Thymoxamine and angle-closure glaucoma].

Thymoxamine is a selective alpha sympathetic blocking agent which may be used to stop the mydriasis induces by phenylephrine, ("safe mydriasis"), to differentiate an open but narrow angle glaucoma from an angle closure glaucoma, to treat an acute closure and to induce miosis without shallowing of the anterior chamber before laser trabeculoplasty.

Anterior Chamber↗
PubMed1983

[Problems and their solutions in today's perimetry].

Progress in the development of perimetry has been slow but certain since the first description of the perimeter by Goldmann in 1946. The creation of static perimetry, and of threshold detection with the multiple stimuli analyser of Friedmann, have been important stages in its development. Automatic perimetry (A.P.) is now available, our choice of apparatus being the Peritest, this instrument combining all the possibilities of A.P. with multiple or single manual perimetry in a very flexible manner. The apparatus allows 153 positions to be examined in the central 25 degrees and 55 in the periphery. The examination is conducted at a suprathreshold level (+ 0,6 log. U) after determination of the patient's eye threshold. Results are grouped in classes on a special chart to facilitate assessment. It is now possible, with the same instrument, to perform a detection A.P. (very useful in suspected glaucoma), a confirmative and limited manual study and, if necessary, a consecutive refined analysis.

Glaucoma↗
PubMed1983

[Modern perimetry: automatic or manual?].

The possible applications of computer assisted static perimetry are examined after one and a half year of personal experience. The general advantage of a computer-assisted perimeter may be the elimination of the influence of the perimetrist on the results. We have employed the PERITEST perimeter because this system allows either full automatic perimetry or two types of manual perimetry with presentation of single or multiple stimuli. All perimetric examination is done after the determination of the individual visual retinal threshold. The examination is always performed at a supraliminal level relative to the individual threshold. The following conclusions can be drawn: 1 - Even after complete elimination of the perimetrist's influence fluctuations in results may be observed. Furthermore, the longer examination the more important patient cooperation becomes in automated perimetry as compared to the manual procedure. So we concluded that the best strategy should be related to the studies of the visual field defects. 2 - For perimetry of presupposed normal visual fields, the multiple stimulus procedure is quite adequate. If some problem appears, the flexibility of the PERITEST enables the use of the single manual stimulus mode. The full automatic examination is done only when there are mild field defects and in intelligent patients. 3 - These techniques enable the description of a new presentation of the classical perimetry's signs of early glaucoma: a loss of 0,5 Log. U.L. (which has the same significance as an isolated relative scotoma.

Computers↗
PubMed1983

[Primary glaucoma and the laser].

The use of the laser for treatment of different forms of primary glaucoma is proposed. In closed-angle glaucoma its use is limited to those cases where a large part of the angle is capable of ensuring drainage of aqueous humor. Pupilloplasty could be an alternative to iridotomy for relieving pupillary blockage. Peripheral circular gonioplasty can enlarge the angle. Finally, the laser can reduce ciliovitreolenticular blockage in malignant glaucoma. In patients with open-angle glaucoma, trabeculoplasty should be performed in the interval between medical and surgical treatments. Initial results appear promising but further study is necessary to evaluate the value of this type of therapy.

Anterior Chamber↗
PubMed1983

[So-called ocular hypertension and new signs of primary open-angle glaucoma].

Between normal and glaucomatous subjects, a group with ocular hypertension exists which is not homogeneous as 10 p. cent of these will develop glaucoma. The problem is to select early eyes at risk. Three new methods of examination have been proposed: the response to the test of contrast sensitivity, the pupillary reaction test of Marcus Gunn, and photographic exploration of the nerve fiber layer of the retina.

Adult↗
PubMed1978

[Results of a double-blind medium-term study comparing effects of timolol maleate and epinephrine in 120 patients with chronic open-angle glaucoma].

A double-blind medium term study of the activity of timolol in chronic open-angle glaucoma was conducted in four French ophthalmological centers, using the same protocol. A total of 119 patients were treated: --60 with timolol; --59 with épinéphrine, for comparison. Results showed a significantly superior efficacy for timolol over épinéphrine, after in weeks of treatment. Good tonometric control was obtained in 81.6% of the patients treated with timolol, against 52.5% of those receiving épinéphrine. In 68% of the glaucomatons patients treated with timolol, good tonometric control was obtained with the lowest dose preparation containing 0.1%. No side-effects were noted during the study, either locally or generally (particularly blood pressure changes).

Chronic Disease↗