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Biomedical subjects

P Bonnet

Publications and source records attributed to P Bonnet.

At least 199 records · Page 11Linked to original sources
PubMedDate not supplied

Relative neurotoxicological properties of five unsaturated aliphatic nitriles in rats.

Motor and sensory conduction velocities (MCV and SCV) and amplitudes of the sensory and motor action potentials (ASAP and AMAP) of the tail nerve were studied in male Sprague-Dawley rats during chronic oral treatment with five unsaturated aliphatic nitriles. Rats were given doses of 12.5, 25 and 50 mg kg(-1) of acrylonitrile, 50, 70 and 90 mg kg(-1) of methacrylonitrile, 25, 50 and 100 mg kg(-1) of trans-3-pentenenitrile and 50, 100 and 200 mg kg(-1) of either 3-methyl-2-butenenitrile or 4-pentenenitrile once a day, 5 days per week for 12 weeks. Moreover, due the the early results obtained after oral treatment, neurophysiological examinations were also carried out in rats exposed by inhalation to 25, 50 and 100 ppm of acrylonitrile for 6 h a day, 5 days per week for 24 weeks. Rats given acrylonitrile orally developed behavioural sensitization characterized by salivation, locomotor hyperactivity and moderately intense stereotypies. Moreover, rats in the high dose group developed weakness in hindlimbs associated with decreases in SCV and ASAP. Rats exposed to acrylonitrile vapours exhibited time- and concentration-dependent decreases in MCV, SCV and ASAP, which were partially reversible after 8 weeks of recovery. None of the other four nitriles caused any abnormal behaviour or any changes in the electrophysiological parameters in spite of an obvious general toxicity. Based upon these results, it can be concluded that the nervous system of the rat appears to be a target following either oral or inhalation exposures of acrylonitrile.

Acrylonitrile↗
PubMedDate not supplied

Sensory and pulmonary irritation of aliphatic amines in mice: a structure-activity relationship study.

The expiratory bradypnea indicative of upper airway irritation in mice was evaluated during a 15-min oronasal exposure to increasing concentrations of sixteen aliphatic amines. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. Moreover, the sixteen amines were tested for pulmonary irritation by measuring the decrease in respiratory rate of (non-anaesthetized) tracheally cannulated mice (RD50 TC). The RD50 and RD50 TC values and their ratios were related to n-octanol/water partition coefficients (log P). The RD50 values associated with exposure to saturated amines ranged from 17 to 300 ppm. The RD50TC values for these saturated amines ranged from 35 to 489 ppm. The RD50 and RD50TC values of saturated amines were closely related to the n-octanol/water partition coefficient, indicating that the more lipophilic amines are more irritant for the upper and lower respiratory tracts. The RD50TC/RD50 values were much less closely related to the n-octanol/water partition coefficient. Based on the results, tentative standards are suggested for the studied amines.

Administration, Inhalation↗
PubMedDate not supplied

Ex vivo technique for evaluating the effect of chemical vapours on mucociliary activity.

An experimental protocol has been developed for the use of rat tracheal explant to evaluate the effects of inhaled chemicals on the mucociliary function. Rats were exposed for 4 h or 7 days (24 h per day) to different concentrations of toluene diisocyanate (TDI). Each rat trachea was subsequently removed rapidly and placed in a humid chamber maintained at 37 degrees C. Mucociliary function was evaluated by video measurements of the two following parameters: mucociliary beating frequency (MCBF) and number of active (A+), partially active (A +/-) and inactive areas (A-). In control tracheas; all areas were active and the MCBF showed hardly any variation around 15.3 Hz. In rats exposed to ca. 0.27 or 0.54 ppm of TDI for 4 h, tracheas showed a significant decrease in the number of active areas and a significant decrease in the MCBF. The same changes were observed in tracheas from rats exposed to approximately 0.05 and 0.10 ppm of TDI for 7 days. After a 7 days recovery period the number of active areas and the MCBF were similar in exposed and control rats except in the group exposed for 7 days to the highest concentrations; these showed only partial recovery. The results of this study showed that this ex vivo method is useful for detecting mucociliary dysfunction.

Administration, Inhalation↗
PubMedDate not supplied

Comparison of the sensory irritation response in mice to chlorine and nitrogen trichloride.

The expiratory bradypnoea indicative of upper airway irritation in mice was evaluated during a 60-min oronasal exposure to increasing concentrations of chlorine and nitrogen trichloride. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each chemical. Chlorine and nitrogen trichloride showed dissimilar concentration-response curves. While the maximal response of nitrogen trichloride was reached in 10 min, the maximal response of chlorine was reached between 45 and 60 min of exposure. The results showed both chemicals to have an irritant potency of the same order of magnitude. The RD50 values of chlorine and nitrogen trichloride were 3.5 and 2.5 ppm, respectively. On the basis of a TLV-STEL (threshold limit value for short-term exposure limit) equal to 0.1 RD50 and a TLV-TWA (time-weighted average) equal to 0.03 RD50, the current TLVs for chlorine seem too high (1 and 0.5 ppm, respectively) and should be reduced to 0.5 and 0.1 ppm, respectively. For nitrogen trichloride, 0.3 ppm and 0.1 ppm are proposed as TLV-STEL and TLV-TWA, respectively.

Administration, Inhalation↗
PubMedDate not supplied

Short-term inhalation test for evaluating industrial hepatotoxicants in rats.

Liver damage was investigated in rat using serum enzyme activities measurements. Responses were recorded 24 h after whole body inhalation exposure to vapors of bromobenzene, carbon tetrachloride, chloroform, o-dichlorobenzene, 1,2-dichloroethane and dimethylformamide as model toxicants. First, rats were exposed during a single 4 h period to different concentrations of each solvent and the minimally active concentration was determined. Second, repeated exposures to chemicals at this concentration level (6 h daily, 2 or 4 days) were used in order to examine whether hepatotoxicity was enhanced. GLDH and SDH are more sensitive and more constant indices than GOT and GPT. It appears that a single exposure period induced more marked serum activities enhancement than repeated exposures.

Alanine Transaminase↗
PubMedDate not supplied

Cochlear pathology induced by styrene.

Hair cells, spiral fibers and spiral ganglion cells (SGCs) coming from cochleae of styrene-treated Long-Evans rats were counted in order to assess the extent and location of the cochlear injury after the solvent inhalation. If the hair cells, and more specifically the outer hair cells (OHCs), were undoubtedly the first targets of inhaled styrene, the histological results of the present study would seem to indicate that neurons of the spiral ganglion were also injured with increasing styrene doses. The degenerative process of SGCs and spiral fibers within the osseous lamina was predominant in the middle and mid-basal turn. The electrophysiological data, obtained by recording near-field potentials from the inferior colliculus, reflected the damages of the SGCs and fibers but were not consistent with the histopathological data of the organ of Corti. Because of the weak correlation between the styrene-induced injury at the level of the organ of Corti and that induced at the level of the spiral ganglion, it is likely that two different intoxication routes exist within the cochlea. Such an assumption is discussed in the present paper.

Animals↗
PubMedDate not supplied

Surgical technique for cardiomyoplasty and iterative transthoracic biopsies in an experimental goat model.

Cardiomyoplasty is a new surgical procedure using transformed skeletal muscle to reinforce or substitute for the myocardium. For the purpose of studying surgical technique and investigating basic questions, we have developed a model of reinforcement cardiomyoplasty. Herein, we describe anesthetic management, surgical technique, and the technique for iterative transthoracic biopsies. This model has proven to be valuable in several long-term studies involving more than 30 goats. Preliminary data to ascertain the efficacy of the proposed technique are provided.

Anesthesia↗
PubMedDate not supplied

The inferior non recurrent laryngeal nerve: a major surgical risk during thyroidectomy.

It is now widely established that systematic intraoperative location and diligent dissection of the recurrent inferior laryngeal nerve during thyroidectomy are the keystones to assure its anatomic and functional preservation. The possibility of abnormal routes, like a non-recurrent cervical course of the inferior laryngeal nerve is an additional major argument for its systematic identification to avoid surgical damage. In 2517 cervicotomies performed between 1992 and 1997 for at least right thyroid lobe excision or parathyroid glands exploration, 20 cases of non recurrent laryngeal nerve were identified (0.79%). The embryological nature of such a nervous anatomical variation results originally from a vascular disorder, named arteria lusoria in which the fourth right aortic arch is abnormally absorbed, being therefore unable to drag the right recurrent laryngeal nerve down when the heart descends and the neck elongates during embryonic development. The surgeon must be aware of the possibility of a non recurrent laryngeal nerve, which arises directly from the cervical vagus and therefore represents a severe potential pitfall during thyroidectomy. Given the absence of reliable clinical symptoms and signs or investigations indicating preoperatively the possibility of a non recurrent nerve, guidelines are given to prevent intraoperatively this major surgical risk.

Aorta↗
PubMedDate not supplied

Damage to the corneal endothelium from anterior chamber intraocular lenses in phakic myopic eyes.

The use of minus power anterior chamber intraocular lenses to correct myopia in phakic eyes has been demonstrated previously to produce a more accurate and predictable correction than corneal refractive surgery techniques. We have examined 15 such eyes by specular microscopy and 10 such eyes by Scheimpflug slit-lamp micrography. One year after surgery, in 5 (36.3%) eyes, there was a decrease of more than 20% in the central endothelial density. Paracentral endothelial damage was present in 13 eyes (86.6%). On the specular micrograph, this damage appeared as an overall decrease in the number of the cells, abnormal cell shape with marked pleomorphism, dark zones, and acellular zones that corresponded to endothelial defects. The slit-lamp anterior segment measurements showed a distance between the edges of the IOL optic and the endothelium which ranged from 0.71 to 1.50 mm. We discuss the criteria for intraocular lens removal.

Adult↗
PubMedDate not supplied

[Comparison of phacoemulsification and manual extracapsular extraction of the lens].

In a prospective study, 60 patients have been operated on for cataract either with phacoemulsification or with manual extracapsular extraction of the lens. All the patients received the same type of PMMA intraocular lens. Visual results and incidence of angiographic cystoïd macular edema were similar in both groups. The mean endothelial cell loss was 10.7% with phacoemulsification and 7% with manual extracapsular extraction.

Aged↗
PubMedDate not supplied

[Breast tuberculosis: apropos of a case].

The tuberculosis of the breast has rarely been observed. A new case is reported. The characteristic clinical symptoms are a firm, no-fixed, painless mass with adenopathies. The disease is rarely bilateral. The most difficult problem is differentiation between tuberculosis and carcinoma in the older patient. The clinical appearance of a pyogenic breast abscess is also very similar to tuberculosis. The most reliable diagnosis studies include bacteriologic cultures of aspirate and histologic examination. The best treatment is a complete surgical excision of the lesion and at least 6 months' postoperative anti-tuberculous chemotherapy.

Aged↗