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Biomedical subjects

A Etienne

Publications and source records attributed to A Etienne.

At least 55 records · Page 3Linked to original sources
PubMed1986

Characterization of platelet activating factor (PAF)-acether-induced contractions of guinea-pig lung strips by selected inhibitors of arachidonic acid metabolism and by PAF-acether antagonists.

The myotropic activities of PAF-acether, leukotriene B4, leukotriene D4 and histamine were compared on superfused guinea-pig lung parenchymal strip and were shown to have the following order of potency: PAF-acether greater than LTD4 greater than LTB4 greater than histamine. The contractile response of the lung parenchyma to PAF-acether was inhibited by aspirin, imidazole and OKY-046, which suggested that thromboxane A2 might play a mediator role in PAF-induced contractions. Neither an antagonist of leukotriene D4, FPL-55712, nor an antihistamine, mepyramine, had any effect on PAF contractions. The activity of a novel antagonist of PAF-acether, BN 52021, was also studied on superfused lung parenchyma contracted by histamine, leukotriene B4, leukotriene D4 and PAF-acether. This compound was without effect on the histamine response but it slightly reduced the contractions elicited by leukotriene D4 and potentiated those by leukotriene B4. BN 52021 (7.1 X 10(-6) M) inhibited by 63% the contraction induced by 5.7 X 10(-13) M PAF-acether and by 52% that induced by 5.7 X 10(-10) M PAF-acether and kadsurenone (8.4 X 10(-6) M), another PAF-acether antagonist, inhibited the same PAF-induced contractions by 75% and 20% respectively.

Animals↗
PubMed1986

Changes in cytosolic free calcium induced by platelet-activating factor in rabbit platelets: specific inhibition by BN 52021 and structurally related compounds.

Increases in cytosolic free Ca2+ concentration induced by PAF-acether in rabbit washed platelets were recorded by using the fluorescent Ca2+ indicator Quin 2. In the presence of 1 mM external Ca2+, PAF-acether 2 X 10(-9) M has been found to increase the intracellular level of free calcium from a basal level of 135.0 +/- 26.9 nM to 2.0 +/- 0.7 microM. Pretreatment of platelets with the PAF-acether receptor antagonists BN 52020, BN 52021 or BN 52022 inhibited dose-dependently the PAF-acether-induced fluorescence signal. This activity was specific for PAF-acether, as shown with BN 52021, the most active derivative, which at 3 X 10(-6) M totally abolished PAF-acether effect without modifying thrombin - or calcium ionophore-induced signal. Kadsurenone, another PAF-acether receptor antagonist exhibited similar efficiency as BN 52021 against PAF-acether stimulation. Studied on PAF-induced aggregation of washed rabbit platelets: BN 52020, BN 52021 and BN 52022 exhibited the same potencies for inhibition as on the Quin 2 signal induced by PAF-acether; their activities were BN 52021 greater than BN 52020 greater than BN 52022. The results confirm that these derivatives, which are structurally closely related act at receptor level. The difference in their efficiencies seem to prove that the binding on its receptor site needs a highly defined chemical structure. They could be useful tools for structure-activity relationship studies in order to elucidate the conformation of the PAF-acether binding site.

Aminoquinolines↗
PubMed1986

Antithrombotic activity of BN 50341, a structurally new compound with anticalcic and PAF-antagonistic properties.

BN 50341, a new benzazepine derivative, which has been shown to possess a mild anticalcic activity decreased (oral or i.v. administration) and also totally reversed (local superfusion) the in vivo electrically induced thrombus formation in rat or guinea-pig artery. These effects of BN 50341 were correlated with an inhibition of PAF-acether- and thrombin-induced platelet activation since it decreased free cytoplasmic calcium mobilization measured on cells loaded with the fluorescent probe Quin 2. Taking into account the beneficial effects of BN 50341 on vascular spasm as well as on the early stage of the process of white thrombus formation, this drug could be of therapeutic interest.

Administration, Oral↗
PubMed1985

[Continuous intragastric pH-metry].

Ambulatory intragastric pH-metry is a suitable method of assessing gastric acidity under conditions of normal daily life. A detailed profile of intragastric acidity is given which is a reproducible individual characteristic. There is a circadian rhythm of gastric acidity in which pH rises during the night and after meals. pH-metry was used to determine the effects of H2-antagonists and antacids, and the results are the basis for the clinical use of intragastric pH-metry.

Antacids↗
PubMed1985

Long-term ambulatory gastric pH monitoring: validation of a new method and effect of H2-antagonists.

A new ambulatory monitoring system was evaluated for long-term measurements of gastric acidity. A close correlation was observed between values indicated by the pH electrode of the system and the pH of simultaneously aspirated gastric juice, suggesting that the electrode signaled the pH of the gastric fluid content. When the pH electrode was passed via an endoscope, and its bulb was placed against the corpus mucosa, a higher acidity was recorded as compared with gastric juice. To test whether the electrodes measured mucosal pH during ordinary test conditions, the readings of pH probes with mechanically shielded bulbs that did not come into direct contact with the mucosa were compared with those of nonshielded probes in identical positions. Similar results were observed, supporting the hypothesis that nonshielded probes measured the pH of gastric contents rather than that of the mucosa. The importance of a standardized electrode position and a fixed meal schedule was demonstrated in simultaneous recordings of antral and fundic pH. Under fasting conditions, acidity was similar in both regions. After ingestion of a meal, gastric contents were more alkaline in the fundus than in the antrum. A wide range of 24-h acidity (19-83 mmol/L) was detected in 25 healthy subjects. The day-to-day reproducibility of the method as revealed in two consecutive 24-h tests was good. The effect of cimetidine and ranitidine on gastric acidity was evaluated in 9 subjects in a double-blind, double-dummy trial. Mean 24-h H+ activity was 37.4 +/- 4.6 mmol/L under placebo medication. It was lower with cimetidine, two doses of 400 mg (23.8 +/- 4.0); cimetidine, four doses of 400 mg (10.2 +/- 3.0); ranitidine, two doses of 150 mg (10.3 +/- 3.6), and two doses of 300 mg (10.0 +/- 3.5), respectively. In conclusion, ambulatory long-term pH monitoring is a suitable method to assess the physiologic pattern of gastric acidity and the effect of antisecretory drugs.

Adolescent↗
PubMed1985

beta-Endorphin in neuroblastoma x glioma hybrid cells.

Acid extracts from mouse Neuroblastoma x rat Glioma hybrid cells have been purified by means of Sep-Pak C-18 and fractionated by high performance liquid chromatography. Each fraction has been submitted to a sensitive beta-endorphin radioimmunoassay and an immunoreactivity peak at camel beta-endorphin retention time was found.

Animals↗
PubMed1985

Evaluation of pirenzepine on gastric acidity in healthy volunteers using ambulatory 24 hour intragastric pH-monitoring.

The effect of pirenzepine on 24 hour intragastric acidity was studied in 10 healthy volunteers using ambulatory 24 hour intragastric pH-monitoring in a double blind crossover study. Tests were performed on the seventh day of ingestion of either placebo, 75 mg pirenzepine or 150 mg pirenzepine per day. The drugs were given at two doses at 8.30 am and 8.30 pm. Mean nocturnal hydrogen ion activity during placebo treatment was 68 mmol/l +/- 9 SEM and was reduced by 75 mg (26%, p less than 0.01) and 150 mg of pirenzepine (36%, p less than 0.01), respectively. Mean diurnal hydrogen ion activity was 32 mmol/l +/- 6 SEM and was not significantly reduced (p greater than 0.1) by either dose of pirenzepine (4% and 12% respectively). Thus, the effect of pirenzepine on intragastric acidity is small, even with high doses of the drug, and becomes apparent only during the night.

Adult↗
PubMed1985

In vivo anti-allergic and anti-inflammatory effects of drugs that inhibit lipoxygenase activity in vitro.

Studies in vitro have already shown that the chemotactic effect of leukotriene LTB4, as well as its pro-aggregatory effect on a suspension of leukocytes, could be inhibited by the lipoxygenase (LO) inhibitor ETYA; moreover a beneficial effect of another LO-inhibitor, diethylcarbamazine, has been shown on experimental asthma. To explore a possible therapeutic application of substances that inhibit 15-LO of soybean in vitro, we have tested several active compounds, namely nordihydroguaiaretic acid (NDGA), phenidone, diethylcarbamazine and mefenamic acid, on the following in vivo inflammation models in the rat: plantar oedema induced by carrageenin; cutaneous vascular hyperpermeability induced by pafacether; pleurisy induced by carrageenin. The correlation between the LO-inhibitor effect of these compounds in vitro and their beneficial effects in the different tests that were performed, as well as the mechanisms of action induced in the different experimental models, are discussed.

Animals↗
PubMed1984

Stimulation of K+ fluxes by diuretic drugs in human red cells.

Two different families of diuretic drugs--(i) (aryloxy)acetic acid diuretics (ethacrynic acid, tienilic acid and (--)-indacrinone) and (ii) furopyridines [(+/-)-BN 50157 and (+/-)-cycletanide]--stimulate K+ movements across human red cell membranes. The kinetic properties of this effect (K+-specificity, saturability, optical isomerism, antagonism by structural analogues, etc.) strongly suggest that it is mediated by a K+-transport system with a specific binding site for some diuretic drugs. The stimulated K+ fluxes are resistant to ouabain, bumetanide and quinine, thus suggesting that they are not mediated by the Na+,K+-pump, Na+,K+-cotransport or by the Ca2+-dependent K+-permeability ('Gardos effect'). The replacement of Cl- by NO3- ions can either decrease, increase or have no effect on the stimulated K+ fluxes, depending on the diuretic drug. Although not conclusive, these observations suggest that the K+ fluxes are not mediated by stimulation of a chloride-dependent K+ carrier. The study of structural analogues showed that the intensity of the stimulation of K+ fluxes is strongly correlated with the magnitude of the natriuretic effect. Curiously, some antiallergic furopyridines are able to inhibit K+ fluxes.

Bumetanide↗
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↗
PubMed1982

A comparison of the dose-response effects of captopril in anesthetized normotensive and renovascular hypertensive rats.

1. Dose-response effects of captopril in an acute model of renovascular hypertension in the anaesthetized rat and in normotensive anaesthetized rats were compared. 2. Intravenous infusions of captopril lowered the blood pressure of both hypertensive and normotensive rats, its minimal active dose being about 0.05 mg/kg. 3. The 0.1 mg/kg dose of captopril normalized the blood pressure of hypertensive rats. 4. The model described herein might be useful for screening inhibitors of the angiotensin-converting enzyme.

Animals↗
PubMed1982

Effects of different diuretics on tetracycline-induced hyperuraemia and hypercreatininaemia in the rat.

Tetracycline injection (45 mg/kg, i.v.) produced increases in plasma urea and creatinine levels in rats. The greatest increases occurred after 24 hr for urea and after 6 hr for creatinine, the latter effect persisted for at least 30 hr. The actions of six diuretics (acetazolamide, bumetanide, chlorothiazide, chlorthalidone, triamterene and indapamide) given orally either as pretreatment (1 hr before tetracycline injection) or post-treatment (4 hr after tetracycline injection) were examined. When given as pretreatments, all six diuretics reduced the hyperuraemia, and generally the hypercreatininaemia, that existed 24 hr after tetracycline injection. In contrast, when given as post-treatments, only bumetanide reduced the increase in urea and creatinine levels. It is postulated that this protective action of diuretics could occur by their displacement of tetracycline molecules from protein binding sites or by a-direct action on renal function.

Animals↗
PubMed1978

Postoperative dislocation after Charnley low-friction arthroplasty.

The dislocation rate after the Charnley arthroplasty with the 22 mm diameter femoral head was 0.8% in 3,820 arthroplasties performed before 1971. Over this era the annual rate ranged from 0.5% to 1.4% without any apparent explanation. Following the routine use of a low position for the socket in the acetabulum and the Long Posterior Wall design of socket, the dislocation rate fell to 0.4% over 4,706 arthroplasties and the annual dislocation rate over 4 years ranged between 0.5% and 0.2%.

Acetabulum↗
PubMed1977

Conversion of fused hips to low friction arthroplasty.

Fifty-four hips converted to low friction arthroplasty between 1965 and 1975 have been reviewed one to eleven years after operation. In many cases malposition had led to degenerative changes in the opposite hip, the lumbar spine or the knee, often with severe loss of function due to pain. It was found that total replacement could give useful relief of pain and improved function, though the range of movement obtained was not as good as in primary replacement. An outstanding feature was the correction of inequality of leg length. In general, the results were much better in cases of ankylosis acquired in adult life than in cases of spontaneous fusion after sepsis in childhood. The most important complication was a single case of sciatic palsy.

Adult↗