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Biomedical subjects

P Bonnet

Publications and source records attributed to P Bonnet.

At least 163 records · Page 9Linked to original sources
PubMed1983

Concentration-dependent behavioral changes in mice following short-term inhalation exposure to various industrial solvents.

Mice were exposed during a 4-hr period to various concentrations of 13 aliphatic or aromatic solvents which affect primarily the central nervous system (CNS). The test compounds were benzyl chloride, butyl alcohol, chlorobenzene, cyclohexanone, 1,2-dichloroethylene, diisobutyl ketone, isopropyl acetate, methyl ethyl ketone, styrene, tetrachloroethylene, 1,1,1-trichloroethane, toluene, and ortho-xylene. After exposure, measurements were made to see whether these neurotoxicants would decrease the immobility developed in a "behavioral despair" swimming test. Each chemical was shown to reduce the total duration of immobility measured over a 3-min period in a concentration-related manner. The systematic determination of the atmospheric concentrations responsible for a 50% decrease in immobility (ID50) permitted classification of the solvents in terms of their relative potencies. The possibility of using such experimental data as tentative guidelines for setting safe levels of work exposure to the neurotoxicants was suggested, considering the existence of quantitative relationships between the ID50 values and the current occupational standards.

Animals↗
PubMed1983

[Maximum power (max W) and index of 2d minute recovery. Correlations with maximal oxygen consumption (max VO2)].

The maximum O2 intake (max VO2) is the best test in order to describe a subject's physical capacity. It is difficult to measure directly. The Astrand normogram gives an indirect and approximate measurement. Two more exact methods are suggested: the maximum developed power in Kg (W/Kg) and the second minute recovery index (iR2) = (formula; see text) where fc2 is the cardiac frequency two minutes after exertion. The correlation is r = 0.94 (p less than 0.001) between max VO2 and W/Kg. The correlation is r = 0.94 (p less than 0.001) between max VO2 and iR2. The iR2 can be determined for a sub-maximal performance at 80 per cent of the maximum and has a high correlation with the max VO2. The max VO2 can thus be determined by these two methods which appear to be the most reliable of the regular tests of physical capacity.

Adult↗
PubMed1983

The pharmacological profile of TX 066 (17 alpha-acetoxy-6-methyl-19-nor-4,6-pregna-diene-3,20-dione), a new oral progestative.

17 alpha-Acetoxy-6-methyl-19-nor-4,6-pregna-diene-3,20-dione (TX 066) has the pharmacological profile of a pure progestogen with no side effect such as androgenic activity. Its pituitary suppressing effect is relatively weak, as is also its antiestrogenic activity. It possesses a powerful antiandrogenic effect, which, in addition to the classic uses for progestogens, may make TX 066 useful in the treatment of certain diseases such as prostatic hypertrophy or the Stein-Leventhal syndrome.

Adrenal Glands↗
PubMed1981

Direct determination of plasma fibrinogen levels by heat precipitation. A comparison of the technique against thrombin clottable fibrinogen with spectrophotometry and radial immuno-diffusion.

We have studied the Thorp method for precipitation of fibrinogen from diluted plasma, using a specific buffer (pH 6.3) at 56 degrees C, and the preferred anticoagulant (EDTA). Nephelometric or turbidimetric measurements of the precipitate were compared with the results obtained by radial immunodiffusion, or by thrombin clotting, of fibrinogen. In the absence of prior proteolysis (as indicated by the presence of fibrinogen and fibrin degradation products), correlations between the methods were excellent (r > 0.99). We conclude that the method of heat precipitation, which is simple to operate and inexpensive, gives results equally as good as the more difficult and time-consuming techniques.

Bilirubin↗
PubMed1981

[Comparison of the effects of acute respiratory acidosis and acute metabolic acidosis on the jaw-opening reflex in the anesthetized dog].

A few effects of carbon dioxide on pain threshold and acid-base balance are known. The purpose of this study was to investigate specifically the variations of analgesia in relation to hypercapnia during general anaesthesia and the respective roles played by carbon dioxide and [H+]. The nociceptive jaw opening reflex was studied on five beagle dogs anaesthetized with alfathesin administered at constant rate under acute hypercapnic conditions and acute metabolic acidosis. Acute hypercapnia did not decrease the jaw opening reflex significantly until a level was reached where PaCO2 values modified blood [H+] (pH) significantly (10 +/- 1.04 kPa corresponding to [H+] 91.5 +/- 13.24 nmol/l (pH 7.04 +/- 0.06) p less than 0.05)). At [H+] 176.2 +/- 42.77 nmol/l (pH 6.7 +/- 0.13) (p less than 0.01) the reflex was only 9.3 +/- 3.9 per cent (p less than 0.001) of its initial value. The infusion of decinormal solution of HCl during constant capnia caused an abrupt drop of the reflex. There was a correlation between reflex and metabolic acidosis (p less than 0.05). The authors conclude that modification of the jaw opening reflex occurs with extreme values of arterial [H+] incompatible with safe anaesthesia and they discuss the mechanisms involved.

Acidosis, Respiratory↗
PubMed1981

Sensory irritation caused by various industrial airborne chemicals.

A short inhalation experiment was performed on mice using 22 industrial airborne irritants. The parameter chosen as an index of sensory irritation was the reflex decrease in respiratory rate. For each compound, systematic determination of the concentration associated with a 50% decrease in the respiratory rate (RD50) permitted, on the basis of the same end point, a comparison of their relative potencies. The possibility of using the obtained data as initial guidelines to establish acceptable Threshold Limit Values (TLVs) in the workplace was examined.

Air Pollutants↗
PubMed1981

[Comparative study of the effects of diazepam and fentanyl on the blink reflex threshold in the normal, conscious human (preliminary study)].

The search in man for experimental techniques suitable for study of the neurospecificity of anaesthetic drugs led us to use the blink reflex. Thirteen female volunteers undergoing gynaecological surgery received as a double-blind basis either 0.2 mg/kg of diazepam (7 cases) or 3 X 10(-1) mg/kg of fentanyl (6 cases) intravenously. The thresholds of the two components of the reflex R1 + R2, of respectively tactile and painful natures, were sought before and for three minutes after the injection of the drugs. The threshold of R2 rose to four times its initial value (P less than 0.001) after diazepam, whilst R1 remained unchanged. Fentanyl was not associated with any change in the thresholds. Study of the blink reflex may be used to dissociate and analyse the effects of two drugs on precise nervous functions. The nature of these functions and of their controls are discussed.

Adult↗
PubMed1981

[Interaction between benzene and toluene in long term inhalation exposure in rats (author's transl)].

Industrial chemicals are seldom used as pure substances; hazards resulting from exposure to mixtures have, however not been solved. Our study deals with chronic inhalation toxicity of a mixture of benzene and toluene; few studies have been completed on this subject. Our results show: - leucopenia with benzene alone, at a concentration of 50 p.p.m., that is not detectable in the presence of toluene; - metabolic variations consisting in: a decrease in the phenol urinary rate versus time with benzene alone; a sharp decrease of this rate from the third month of exposure on, in presence of toluene.

Animals↗
PubMed1977

Possible high dosage gentamycin therapy in infected neutropenic patients.

Serum gentamycin levels have been studied in 23 neutropenic infected patients after high doses (62 mg/m2 and 72 mg/m2) of the drug, we observed: a higher gentamicin level than with an usual dosage, levels under the ototoxic 10/ml level, no renal failure, and, no patient ototoxicity.

Agranulocytosis↗
PubMed1976

Standardization of an experimental immune uveitis in the rabbit for topical testing of drugs.

An egg albumin uveitis of the Arthus active type was developed in the rabbit. The experimental conditions were investigated in detail with regard to the following factors: influence of the number of sensitizing injections on serum antibody production, length of the recovery period which elapsed between sensitization and challenge, and influence of the size of the challenging dose on the severity of the inflammatory response. To develop the procedure optimally, emphasis was given to criteria of evaluation. Refractive index, protein and immunoglobulin assays in the aqueous humor of inflamed eyes were significantly correlated. These objective measures were considered more reliable than arbitrary grading systems. In addition, supportive histopathologic observations have been made in rabbit eyes. The above studies led to a reproducible model of uveitis in which drugs were tested topically. Dexamethasone phosphate in solution and indomethacin in suspension were effective in a dose-related manner. 6-Mercaptopurine did not demonstrate a useful anti-inflammatory effect.

Administration, Topical↗