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Biomedical subjects

G Bouvier

Publications and source records attributed to G Bouvier.

72 records · Page 4Linked to original sources
PubMedDate not supplied

Intracerebral amplitude distributions of the auditory evoked potential.

Intracerebral auditory evoked potentials were recorded from multi-contact electrodes chronically implanted in frontal, temporal, and parietal regions of the brains of 10 epileptic patients. Binaurally presented tones produced a large widely distributed biphasic potential with a close latency correspondence to the scalp vertex response. In each hemisphere, this intracerebral response inverted in polarity from posterior temporal to frontal sites. This response also showed large amplitude changes in the inferior parietal lobe. The distribution of this response is compatible with bilateral posterior temporal sources with a dorso-frontal orientation.

Adult↗
PubMedDate not supplied

Insecticide urinary metabolites in nonoccupationally exposed populations.

The wide use of insecticides in agricultural and residential settings has resulted in environmental contamination, leading to increased concern about exposure of the population and possible chronic effects on health. This review summarizes the studies that have measured urinary metabolites to assess exposure of nonoccupationally exposed population to nonpersistent insecticides, organophosphates (OPs), carbamates, and pyrethroids. Electronic search yielded 36 different studies performed in a small number of countries for the last 20 years, most of them dealing with OP urinary metabolites. Dialkylphosphates, specific metabolites of OPs, and specific metabolites of pyrethroids or carbamates, have been investigated. Results indicate that a wide range of the population, adults as well as children, is exposed to OPs and to a lesser extent to pyrethroids and carbamates. Levels are one to several orders of magnitude lower than those in occupational studies. The contribution of the different sources of insecticide exposure remains uncertain. Food contamination, as well as environmental and residential contamination, appears to influence exposure, especially in the case of children. Residential use of insecticides, having pets, and living near gardens or fields have all been inconstantly related to higher urinary metabolite levels. Occupational exposure of the parents, especially of the agricultural workers, seems to be a predictive factor of higher exposure of their children. More studies investigating every source and pathway of exposure of randomized population samples and in other countries than the United States, in particular in developing countries, could improve our knowledge of factors influencing insecticide exposure of the population.

Animals↗
PubMedDate not supplied

Electrical stimulation of the human brain in epilepsy.

The concordance between the epileptogenic area as determined by intracranially recorded spontaneous seizure onset and that determined by electrically induced auras or seizures in 126 patients with medically intractable epilepsy was studied. Four to 11 multicontact depth electrodes were chronically implanted in patients as part of a preoperative investigation procedure. Localization of the epileptic area was obtained from the recording of three spontaneous seizures and from stimulation data including self-reported auras, seizures, and intracranial EEG afterdischarges recorded during an incremental stimulation sequence at all cortical pairs of contacts. Positive responses to stimulation were obtained in 63% of patients. Concordance between spontaneous and induced auras or seizures was greater than 90% with single unilateral foci and less with multiple foci. Stimulation data reliably predicted the resection area in unilateral and bilateral temporal foci but not in other locations. Afterdischarge thresholds were not reliable predictors of the spontaneous seizure focus. The intracranial stimulation procedure used appears to provide useful confirmatory and complementary localizing information in relation to that obtained from spontaneous seizures.

Brain↗
PubMedDate not supplied

Urinary excretion of nitrosamino acids and nitrate by inhabitants of high- and low-risk areas for nasopharyngeal carcinoma in southern China.

The hypothesis that endogenous synthesis of nitrosamines from dietary precursors is a risk factor for nasopharyngeal carcinoma (NPC) in China was tested by applying the nitrosoproline (NPRO) test to subjects living in high- and low-risk districts for NPC in Zangwu county, Guangxi region, in southern China. Samples of 12-h urine were collected from 77 subjects: (a) before any treatment; (b) after ingestion of proline; and (c) after ingestion of proline together with vitamin C. NPRO, other nitrosamino acids, and nitrate were measured as indices of exposure to preformed and endogenously formed nitrosamines or their precursors. The NPRO level after proline intake was significantly increased in subjects from the high-risk area (P = 0.012) and markedly reduced after ingestion of ascorbic acid (P = 0.007), but such an effect was not seen in subjects from the low-risk area. Levels of N-nitrosothiazolidine-4-carboxylic acid and the sum of nitrosamino acids in subjects in the high-risk area were significantly reduced by ascorbic acid (P < 0.01) but were not reduced in subjects from the low-risk area. The urinary nitrate level was about twice as high in subjects from the high-risk area. In subjects from high- and low-risk areas combined, NPRO levels in any of the three dose groups were highly correlated with nitrate levels (P = 0.0001). These results demonstrate a higher potential for endogenous nitrosation in subjects living in the high-risk area of NPC and suggest the occurrence of nitrosation inhibitors in the diet consumed in the low-risk area.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗