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Biomedical subjects

A Prévost

Publications and source records attributed to A Prévost.

13 recordsLinked to original sources
PubMed1999

Effects of amifostine on perfused isolated rat heart and on acute doxorubicin-induced cardiotoxicity.

PURPOSE: To determine the effects of amifostine on an isolated perfused rat-heart model and its protective activity with regard to cardiotoxic doxorubicin perfusion. METHODS: Langendorff constant-pressure isolated rat-heart preparations were used to analyze the effects of the drugs during a 40-min period of perfusion after a 20-min stabilization interval. The first study was conducted with amifostine alone (controls and 10(-6), 10(-5), and 10(-4) M amifostine; n=6 in each group). The second study was conducted with amifostine and doxorubicin (controls, 2.5 x 10(-5) M doxorubicin, 2.5 x 10(-5) M doxorubicin and 10(-5) M amifostine, and 2.5 x 10(-5) M doxorubicin and 10(-4) M amifostine; n=4 in each group). RESULTS: Amifostine had no significant effect on hemodynamic parameters at 10(-6), 10(-5), and 10(-4) M concentrations. However. amifostine increased the coronary flow expressed as a percentage+/-SEM of the baseline flow as follows: 82+/-4% for controls, 95+/-6% for 10(-6) M amifostine, (P=0.13), 111+/-4% for 10(-5) M amifostine (P < 0.01), and 104+/-3% for 10(-6) M amifostine (P < 0.01). When we commenced an amifostine perfusion 20 min in advance of and then during a 40-min perfusion with doxorubicin, at a cardiotoxic concentration of 2.5 x 10(-5) M the left ventricular pressures (LVDP, expressed as percentages +/-SEM of the baseline LVDP before doxorubicin) were 55+/-3% for the doxorubicin controls, 68+/-2% for doxorubicin with 10(-5) M amifostine (P=0.05), and 80+/-3% for doxorubicin with 10(-4) M amifostine (P < 0.01). Whether this protective effect might be related to the known free-radical-scavenging activity of amifostine remains to be determined. CONCLUSION: On a Langendorff-type model of rat heart, 10(-5) and 10(-4) M amifostine alone induced a coronary dilation and, when associated with a cardiotoxic concentration of 2.5 x 10(-5) M doxorubicin, 10(-5) and 10(-4) M amifostine displayed a cardioprotective effect.

Amifostine↗
PubMed1997

Cardiotoxic effects of salmeterol in comparison with salbutamol on the isolated perfused Langendorff-heart of the rat.

beta 2-Adrenoceptor agonists used in the relief of bronchospasm have long been known to produce circulatory side-effects. Salmeterol (CAS 89365-50-4) is a novel long acting highly selective beta 2-agonist. We used the Langendorff-heart rat model (constant perfusion pressure) to compare the direct effects of salbutamol (CAS 18559-94-9, SAL) and salmeterol (SMT) on the cardiac performances and their toxic cardiac effects (induced by 3 mmol/l perfusate calcium). At the first step the concentration-effect curve was established for the maximal concentration (Cmax) of salbutamol leading to the maximal chronotropic effect on the heart for 20 min after a 20 min stabilization period (basal values). All hearts were consequently submitted to a 20 min Krebs-Henseleit perfusion in order to study the reversibility of the myocardial performances. The types of the myocardial and coronary beta-adrenoceptors involved in SAL (Cmax) effects were identified using a selective beta 1 (atenolol) and a beta 2 (butoxamine) antagonist. SAL induced an increase in the heart rate via a selective stimulation of the beta 1-adrenoceptors (beta 1-AR). SMT appeared to be more potent than SAL on the heart rate. Direct toxic drug effects on the heart appeared gradually with SAL whereas they appeared sharply at the highest concentration of SMT. The enzyme leakage observed during the recovery period was more pronounced with SMT than SAL. Perhaps, this phenomenon might be due to the lipophilicity of SMT. However, these direct cardiac effects of SMT have to be considered in association with its airway smooth muscle relaxant effect (therapeutic effect) which has been proven much more potent than those of SAL. Therefore SMT was less cardiotoxic than SAL at similar therapeutic concentrations.

Adrenergic beta-Agonists↗
PubMed1996

Erythema multiforme due to pyrazinamide.

Drug-induced erythema multiforme is reported with many antimicrobial and antipyretic medications. We present one patient who experienced erythema multiforme and urticaria after administration of pyrazinamide for treatment of cutaneous tuberculosis. The side-effects of pyrazinamide include hepatic or dermatologic disorders, but erythema multiforme has not yet, to our knowledge, been described. Clinical features and discontinuation and reintroduction of the drug led us to consider pyrazinamide the cause of the erythema multiforme, but allergologic studies remained negative, except for the presence of circulating immune complexes. The mechanism of this eruption remains obscure, and definite withdrawal of pyrazinamide seems to be the best therapeutic choice.

Aged↗
PubMed1996

[Carcinoid thymus tumor at an advanced age: diagnostic value of mediastinal needle biopsy with computerized tomography].

Carcinoid tumour of the thymus is a rare neuroendocrine tumour particularly at an advanced age. The authors report a case of a mediastinal mass in a man aged 85, the mass had remained asymptomatic for a long time. It was decided to achieve a diagnosis because the tumour was causing local compression: a mediastinal needle biopsy under computerised tomographic control confirmed that this was a carcinoid tumour and a study of the biopsy material using an electron microscope showed neurosecretory granules. A sternotomy enabled the tumour to be excised but a post-operative Pseudomonas pneumonia led to the death of the patient. This case underlines the diagnostic place of mediastinal needle biopsy in the presence of a mediastinal tumour. The technique can be carried out under computerised tomography or ultrasonography and this can be associated with a study of the biopsy specimen using electron microscopy which enables the diagnosis to be made before any therapeutic decisions. The treatment of choice of a carcinoid tumour of the thymus is surgery which confirms the tumour limits and also its thymic origin. Tumour excision can be completed using radiotherapy or even chemotherapy.

Age Factors↗
PubMed1995

[Extrinsic allergic alveolitis of occupational origin].

Occupational factors encountered in farming and other agricultural activities produce a particular risk for respiratory diseases. For some, such as extrinsic allergic alveolitis, diagnosis depends upon a range of epidemiological, clinical, radiological and immunological arguments. Farmer's lung is one of the most common form of extrinsic allergic alveolitis. Bird breeder's lung is another, the list is long. The environmental allergens likely to affect alveoli and interstitial tissues have been identified, but simple detection of antibodies does not constitute a pathognomonic criterion of extrinsic allergic alveolitis. Co-immuno-electrodiffusion is a rapid and sensitive technique for the demonstration of remarkable precipitating systems of extrinsic allergic alveolitis. This investigation enables subjects who really have the disease to be distinguished from contact subjects. Diagnosis is important to prevent development of a disabling and irreversible pulmonary fibrosis.

Adrenal Cortex Hormones↗
PubMed1995

Compared effects of ruthenium red and cis [Ru(NH3)4Cl2]Cl on the isolated ischaemic-reperfused rat heart.

The sequence ischaemia-reperfusion is characterized by reperfusion damage. The calcium overload occurring at the beginning of reperfusion is one of the main mechanisms responsible for reperfusion damage. Ruthenium red, a blocker of the mitochondrial calcium uniport system, could prevent this damage by preserving the ATP synthesis in the mitochondria. We tested ruthenium red and another ruthenium compound, cis-tetrammine dichlororuthenium (III) chloride in our experimental model of ischaemic-reperfused rat hearts. After a 15 minute-stabilization period, the hearts were submitted to a 30 minute global ischaemia period and then reperfused for 45 minutes with the standard perfusion solution or with ruthenium red or cis-tetrammine dichlororuthenium (III) chloride at 1, 3 or 9 microM. Ruthenium red at 3 microM exerted a protective effect in our experimental conditions by showing a significant improvement of the contractility recovery at the end of reperfusion and a significant decrease of the malondialdehyde production, which reflects free radical production. The cis-tetrammine dichlororuthenium (III) chloride (containing 1 Ru ion per molecule) at 9 microM was slightly less efficient than ruthenium red at 3 microM (containing 3 Ru ions per molecule). The heart ruthenium binding was better for the ruthenium red than for the cis-tetrammine dichlororuthenium (III) chloride, suggesting a role of the ruthenium ion complexation in the crossing of the membrane, whereas the cardiac effect seemed to be linked to the ruthenium ion heart concentration, which was similar for the ruthenium red at 3 microM and for the cis-tetrammine dichlororuthenium (III) chloride at 9 microM. One can hope that ruthenium compounds would limit reperfusion damage and infarct size after ischaemia in in vivo models.

Animals↗
PubMed1994

Molecular basis for degenerate T-cell recognition of one peptide in the context of several DR molecules.

We report the study of one CD4+ T-cell clone that recognizes peptide HA306-320 in the context of autologous DR1101 molecules as well as of allogeneic DR1301, DR0402, DR1501, and DR1601 molecules. This degenerate T-cell recognition is mediated by a single T-cell receptor (TCR) as judged by both TCR-V beta sequencing and cold-target competition assays. Restriction analysis shows that substitutions of DR residues within the third hypervariable region result in a loss of T-cell reactivity, which is restored by additional substitutions in the first and/or second hypervariable regions. Thus, there is no correlation between antigen presentation abilities of the different allelic DR products and the degree of sequence homology between these products. DR residues whose substitution is compatible with T-cell recognition potentially interact with peptides rather than with TCRs by virtue of their location in the floor of the groove or as previously documented for residues of the alpha-helix. Furthermore, antigen presentation by allogeneic DR molecules occurs independently of their affinity for the peptide, as determined in cell surface-binding assays using biotinylated HA306-320. Altogether these data suggest that degenerate T-cell recognition mainly depends on an influence of polymorphic DR residues on the configuration adopted by the peptide in the DR groove so that the epitope is left intact.

Amino Acid Sequence↗
PubMed1994

Baker's asthma related to soybean lecithin exposure.

We report two cases of soybean-lecithin-induced asthma in bakers. The patients experienced clinical symptoms in relation to an occupational exposure to this additive. Skin tests were positive with soybean lecithin, RAST showed a sensitization to soybean, and bronchial challenge tests were positive for a dilution of 10(-3) with this allergen. The same tests remained negative among healthy and asthmatic controls. Soybean lecithin, a common additive in bakery, must be added to the list of numerous aeroallergens involved in baker's asthma.

Adult↗
PubMed1994

Gallium chloride effects on neonatal rat heart cells in culture, in standard and oxidative conditions.

The effects of gallium chloride (GaCl3) at 7.17, 28.68 and 114.7 microns (0.5, 2 and 8 mg/l of Ga3+) were checked in cardiac cells derived from 2-4 day-old newborn rats, cultured for 72 h in Eagle's minimum essential medium (MEM), enriched with 10% foetal calf serum (v/v) and 2 mM of glutamine at 37 degrees C, with 95% air plus 5% CO2. After 3 hours of standard culture conditions (MEM with glucose 5 mM), Ga treatment induced an increase of glycogen stores without any influence on ATP, ADP, and AMP concentrations. A slight and transient decrease in the beat rate was noted after 15 min of exposure to GaCl3 at all concentrations, whereas there was no difference in the beat rate nor in the cell contraction amplitude after 3 hours of exposure. After 1.5 h in conditions of oxidation (Tyrode solution without glucose, FeCl2 20 microM, ascorbic acid 0.2 mM), GaCl3 at 8 mg/l decreased the malondialdehyde (MDA) production as assessed by the decrease of intracellular concentrations and the decrease of its release in the supernatant. The decreased MDA production following oxidative stress, the increase in glycogen stores in normal oxygen concentrations, as well as the maintenance of ATP concentrations and the lack of any chronotropic effect induced by GaCl3 suggests a protective rather than a deleterious cardiac effect.

Animals↗
PubMed1994

[Importance of serum TPA determination in bronchopulmonary cancer. A comparative study of CEA, CA 19.9 and NSE].

This study concerns 45 patients group one suffering from broncho-pulmonary cancer, the diagnosis was obtained by bronchial biopsies or by transparietal puncture using a scanner: there were 35 non-small cell bronchial carcinomas (CNPC) and 10 small cell bronchial cancers (CPC). The control patients (99 patients) were divided up as follows: 44 pleuro-pulmonary infections (group two) and 55 with respiratory failure of various causes other than infectious episodes (group three). In group one the level for TPA was positive in 30 cases (the threshold value was 90 units per litre), 9 for CA 19.9, 7 for ACE and 9 for NSE. The overall sensitivity was thus better for TPA. There was no correlation between TPA and type of tumour histology nor between the different markers. Their association did not improve the sensitivity. The NSE however, remained the most sensitive test for the diagnosis of CPC with six positive tests out of ten. In the control population, the specificity of TPA (66%) was less than that of ACE (100%) or of CA 19.9 (94%) and the false positives were significantly more numerous in group two: 21 patients had a positive test compared to only 12 in group three. Finally we noticed an increase in the level of TPA contrary to other markers, as a function of the extent of the disease from the carcinoma (CNPC unique). The TPA is thus the most sensitive and it turns out to be better reflector to the extent of the tumour disease than either ACE, CA 19.9 or NSE but this applies uniquely to non-small cell carcinoma.

Adenocarcinoma↗
PubMed1993

[Bronchial biopsy, curative treatment for cancer in situ?].

Bronchial carcinoma in situ is an intra-epithelial proliferation of tumour which does not cross the basement membrane and is asymptomatic. The evidence for this cancer often rests on a biopsy carried out on a bronchus which may show simple inflammation or may even be normal. We report a new observation on a bronchial carcinoma in situ which was completely ablated after a bronchial biopsy. However surgery remains the first form of treatment for bronchial cancer. If the patient is inoperable, endobroncho-cryotherapy, radiotherapy or phototherapy may be tried but tumour recurrence remains a possibility.

Aged↗
PubMed1990

[Conservative restoration with composite resins].

At the beginning of the century the radical approach to treatment of an occlusal surface carie of a molar were related to the principles developed by G.V. Black. Extension for prevention in the occlusal fissures, whether they were decayed or not, respected the needs of that era. Those ideas were based on the epidemiology of dental caries and mechanical properties of the filling materials in use to treat them. The parameters of treatment have changed, the reality is not the same. Nowadays, conservative composite resin restorations, demand a less destructive approach for small carious pit and fissure lesions in both the primary and permanent dentitions.

Composite Resins↗