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Biomedical subjects

P Bonnet

Publications and source records attributed to P Bonnet.

At least 109 records · Page 6Linked to original sources
PubMed1991

[Comparative study of 2 types of bifocal implants by measurement of visual acuity and contrast sensitivity].

Evaluation of multifocal IOLs suggests the possibility of two retinal images, one for near and one for distant vision. But the optic principles of multifocal IOLs created overlying images and incident light division. We performed this study to evaluate visual acuity and contrast sensitivity for two types of bifocal IOLs (3M bifocal and IOLAB bifocal IOL) and for a control group of monofocal IOL testing in different levels of luminance simulating the normal environmental conditions of the patient's experience. The results showed a visual functional loss especially at the low luminance level for the 3M bifocal group and at bright luminance for the IOLAB bifocal group, which was previously unknown with and consequences for the indications and exclusions of this kind of IOL.

Aged↗
PubMed1991

Effects of hypoxia on a potassium channel in cat cerebral arterial muscle cells.

We have shown that exposure of isolated cat cerebral arterial muscle cells to hypoxic environments increases K+ channel activity when recorded in the cell-attached mode. Inhibition by glibenclamide of the "hypoxia-induced" increase in K+ channel activity may suggest that increased activity is mediated by an ATP sensitive K+ channel. Thus, the level of O2 may modulate cerebral vascular tone by an action on membrane K+ channels, possibly mediated by the concentration of intracellular ATP.

Animals↗
PubMed1990

Adrenal-dependent leucopenia after short-term exposure to various airborne irritants in rats.

Leucopenia without any change in differential or red blood cell counts was observed in rats exposed for 4 h to increasing concentrations of the following airborne irritants: acetic acid, benzyl chloride, 1,2-dichlorobenzene, ethyl acetate, ethyl acrylate, formaldehyde, isophorone, mesityl oxide, phenol, styrene, toluene diisocyanate and vinyl toluene. This effect was abolished by adrenalectomy. Vinyl toluene and 1,2-dichlorobenzene induced leucopenia at levels as low as their current occupational standards of 50 ppm. With the exception of 1,2-dichlorobenzene, the tested compounds caused leucopenia only when exposure reached the irritant level. It is discussed that stress associated with the irritative effect of chemicals can confound specific haematological effects.

Adrenal Glands↗
PubMed1990

Decrease in the rat bronchial acetylcholinesterase activity after toluene diisocyanate inhalation.

Acetylcholinesterase (AChE) activity was measured in bronchial tissue homogenate and blood from rats subjected to single and repeated 4-h daily inhalation exposure to toluene diisocyanate (TDI) or control atmospheres. A single 4-h exposure to TDI in the concentration range of 0.7-4.3 ppm did not decrease AChE activity in bronchial tissue but a 4-h exposure to 0.6 ppm TDI, or greater, for two consecutive days did reduce this activity (19% to 33% of the controls). Increasing the level of exposure to TDI for two consecutive days from 0.6 to 4.0 ppm and extending the length of exposure to 1.2 ppm TDI from 2 to 4, 9 or 14 days produced no further decrease in bronchial ACHE activity. Throughout these experiments, blood AChE activity remained unchanged. In rats exposed to 0.3 or 1 ppm TDI for 3 weeks, staining of the bronchial smooth muscle for AChE was reduced (36% of the controls) after exposure to 1 ppm TDI. These results support, for the first time, in vivo and localized anti-AChE activity by TDI.

Acetylcholinesterase↗
PubMed1990

[Castleman's disease (giant lymph node hyperplasia): clinical, biological and developing polymorphism. Apropos of 4 cases].

Four cases of plasma cell type Castleman's disease (CD) are described. Two patients had localized forms (one mediastinal and the other mesenteric) and presented systemic manifestations associated with hypergammaglobulinemia and severe anemia. In both cases, the lesions were revealed by computerized tomography scans and cures were obtained by the complete surgical removal of the masses, which led to the rapid disappearance of the systemic manifestations. The other 2 patients had the multicentric form of CD and presented more extensive clinical and biological symptoms. One of these developed severe peripheral neuropathy and endocrine anomalies during the late phase of his disease, which led us to discuss the relationship between multicentric CD and the POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin change) syndrome first described in Japan. Three of our patients presented with hypochromic microcytic anemia too severe to be explained by an inflammatory syndrome alone, and was likely due to several mechanisms. The etiology of CD remains unknown. The histological characteristics of angiofollicular lymph node hyperplasia are among the most important criteria for the diagnosis of localized and multicentric forms of CD, which can easily be made on a lymph node biopsy. However, it must be noted that this lesion can also be observed (but only rarely) in HIV (human immunodeficiency virus) - infected patients. The localized form is always considered to be benign, but, to date, there is no formal argument definitively supporting the malignancy of the multicentric one, in spite of its clinical similarity to a lymphoproliferative syndrome.

Adult↗
PubMed1989

Structure and activity of proteins from pathogenic fungi Phytophthora eliciting necrosis and acquired resistance in tobacco.

The phytopathogenic fungi Phytophthora cryptogea and Phytophthora capsici cause systemic leaf necrosis on their non-host tobacco; in culture they release proteins, called cryptogein and capsicein, which elicit similar necrosis. In addition, both proteins protect tobacco against invasion by the pathogen Phytophthora nicotianac, the agent of the tobacco black shank, that is unable to produce such an elicitor. Cryptogein causes visible leaf necrosis starting at about 1 microgram/plant, whereas 50-fold as much capsicein is required for the same reaction. Capsicein induces protection even in near absence of leaf necrosis. The activities of both elicitors are eliminated upon pronase digestion. They are proteins of similar Mr (respectively 10,323 and 10,155) and their complete amino acid sequences were determined. They consist of 98 residues, with some internal repetitions of hexapeptides and heptapeptides. 85% identity was observed between both sequences: only two short terminal regions are heterologous, while the central core is entirely conserved. Secondary structure predictions, hydropathy and flexibility profiles differ only around position 15 and at the C-terminus; these modifications could play a role in the modulation of their biological activities. After a search of the sequence data bases, they appear to be novel proteins.

Algal Proteins↗
PubMed1989

Nasal irritation and pulmonary toxicity of aliphatic amines in mice.

The expiratory bradypnoea indicative of upper airway irritation in mice was evaluated during a 15-min oronasal exposure to increasing concentrations of twenty aliphatic amines. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice (RD50) was calculated for each test compound. Moreover, eight out of the twenty amines were tested for pulmonary toxicity in mice and for the effects of a 120-min exposure on the respiratory rates of non-anaesthetized, tracheally cannulated mice (RD50TC). Both allylamine and diallylamine showed RD50 values of 9 ppm and 4 ppm, respectively, while the RD50 values associated with exposure to saturated amines ranged from 50 to 200 ppm. Among the eight amines tested for both upper airway irritation and pulmonary toxicity, diisopropylamine and di-n-butylamine showed a RD50TC/RD50 ratio of less than 1, indicating that the respiratory toxicity induced by these two amines would be related primarily to pulmonary effects. On the basis of prior predictions proposed for upper airway irritants, tentative standards are given for ten amines. Moreover, it is suggested that the basis of standards for industrial exposure to diisopropylamine and di-n-butylamine should be specified.

Amines↗
PubMed1989

The effects of maternally inhaled formaldehyde on embryonal and foetal development in rats.

Sprague-Dawley rats were exposed to 0, 5, 10, 20 or 40 ppm formaldehyde for 6 hr/day from day 6 to 20 of gestation. On day 21 of gestation the rats were killed for evaluation of maternal reproductive and foetal parameters. No effect on embryonic or foetal lethality, nor significant alterations in the external, visceral or skeletal appearance of the foetuses were noted in any of the exposed groups. Significant concentration-related reduction of foetal body weight occurred at 20 and 40 ppm, and at 40 ppm foetal body weights were 20% less than those of the controls. Maternal toxicity, indicated by significant reduction in body weight and absolute weight gain, was observed at 40 ppm. The results of this study show that formaldehyde is slightly foetotoxic at 20 ppm. Neither embryolethal nor teratogenic effects were observed following inhalation exposure at levels up to 40 ppm.

Animals↗
PubMed1989

Acetone compared to other ketones in modifying the hepatotoxicity of inhaled 1,2-dichlorobenzene in rats and mice.

The ability of acetone and 3 other ketone vapours to influence the hepatotoxicity of inhaled 1,2-dichlorobenzene (DCB) was examined in rats and mice. Methylethylketone, methylisobutylketone or cyclohexanone increased liver cytochrome P-450 content and glutathione-S-transferase (GST) activity, but did not affect serum glutamate dehydrogenase (GLDH) activity in rats. Pre-exposure to these ketones enhanced DCB-induced increase in serum GLDH activity (8-63-fold), while the increases in cytochrome P-450 content (33-86%) and GST activity (42-64%) were identical to those resulting from exposure to ketones alone. Each of the 3 levels of exposure to acetone elicited cytochrome P-450 and GST responses comparable with those caused by the other ketones. In spite of that, acetone pre-exposure potentiated (4785 ppm), reduced (10670 ppm) or suppressed (14790 ppm) DCB-induced liver toxicity. In mice, the 3 ketones mentioned above interacted with DCB on centrolobular liver glucose-6-phosphatase (G-6-Pase) while acetone pre-exposure elicited an interactive G-6-Pase response in the mediolobular area alone, suggesting topographic change.

Acetone↗
PubMed1989

Inhalation teratology study on hexachloro-1,3-butadiene in rats.

Pregnant rats were exposed to 0, 2, 5, 10 or 15 ppm hexachloro-1,3-butadiene (HCBD) 6 h/d during days 6-20 of gestation. Maternal reproduction and fetal parameters were evaluated on gestational day 21. A significant reduction in maternal weight gain and in fetal body weight occurred at 15 ppm. The incidences of external, visceral and skeletal alterations were not significantly increased in any of the HCBD-exposed groups. It is concluded that exposure of pregnant rats to HCBD by inhalation of concentrations high enough to cause maternal and slight fetal toxicity is neither embryotoxic nor teratogenic.

Animals↗
PubMed1989

Effects of inhalation exposure to carbon disulfide and its combination with hydrogen sulfide on embryonal and fetal development in rats.

Pregnant rats were exposed to 0, 100, 200, 400 or 800 ppm of carbon disulfide (CS2), 100 ppm of hydrogen sulfide (H2S) alone or in combination with 400 and 800 ppm CS2, 6 h/d during days 6-20 of gestation. Maternal reproduction and fetal parameters were evaluated on gestational day 21. Treatment with 100 or 200 ppm CS2 or with 100 ppm H2S caused no maternal toxicity or adverse effects on the developing embryo or fetus. Exposure to 400 or 800 ppm CS2 resulted in a low incidence of club foot and in a significant reduction of maternal weight gain. Significant increases in unossified sternebrae occurred at 800 ppm CS2 and reduction of fetal body weight at 400 and 800 ppm CS2. The latter effect was enhanced by combination with 100 ppm H2S. These results support the conclusion that, at levels of exposure associated with maternal toxicity, CS2 leads to an increase in incidence of club foot and to fetal toxicity which is enhanced by simultaneous exposure to H2S.

Administration, Inhalation↗
PubMed1989

Contractile responses to hypoxia of isolated rings from the left branch of rabbit pulmonary artery.

Contractile responses of left extrapulmonary artery segments with either intact or damaged endothelium were examined with changes in PO2 at constant pH. Hypoxia consistently reduced noradrenaline-induced contractions. This hypoxia-induced relaxation was sometimes followed by a contraction and a second relaxation. Hypoxia-induced relaxations were also obtained if precontraction was elicited with KCl (40 mM), but no triphasic response was observed. Relaxations faded away with time and only contractions were then observed. Relaxations were more considerable in rings from young animals and, although always present, decreased with the age of the animal. Endothelium damage reduced hypoxia-induced relaxations. Indomethacin, a potent blocker of cyclooxygenase, increased hypoxia-induced contraction and reduced relaxation in segments with intact endothelium. Without endothelium the indomethacin effect was less significant. It is concluded that the response to hypoxia of the pulmonary artery is similar to that of systemic vessels. Endothelium seems to play a modulatory role in the hypoxia-induced response in extrapulmonary artery. Prostaglandin metabolism seems to play a minor role in this modulation.

Acetylcholine↗
PubMed1989

Long term results (greater than 5 years) in patients with peritoneovenous shunting for intractable ascites: liver function and cancer mortality.

This report is based on twenty-eight (26%) of 107 patients included in a protocol for prospective evaluation of elective peritoneo-venous shunting for intractable ascites in cirrhosis. These patients had no other procedures and survived more than 5 years after the operation. All patients were free of ascites except one in whom it was mild. One patient refused follow-up. Shunt patency was assessed in 23 patients In 14 patients (60.9%), the shunt was obstructed and the superior vena cava was occluded in 5 of them. In 9 patients (39.1%), the shunt was still functioning. No clinical or biological parameters differentiated these two groups of patients. Of the 24 patients who were alcoholics, 2 abstained completely and 20 significantly reduced their drinking habits. In 25 patients, the Pugh's score improved and was A at the time of the study. Seven patients (25.9%) developed a malignant tumor of the oro-pharynx or digestive tract, all other patients were alive and in good health. This study suggests that patients with intractable ascites treated by a peritoneo-venous shunt may survive for a long period. In patients abstaining from heavy drinking, it may function as a therapeutic bridge permitting spontaneous improvement of liver function. The risk of supervening neoplasms suggests that a continuous follow-up of these patients is warranted.

Adult↗