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Biomedical subjects

P Bouchet

Publications and source records attributed to P Bouchet.

At least 19 recordsLinked to original sources
PubMed2006

Antifungal Activity of Chromolaena odorata (L.) King & Robinson(Asteraceae) of Cameroon.

An aqueous ethanol extract of leaves of Chromolaena odorata and some of its fractions were examined for their antifungal properties by dilution methods on solid and liquid media, using yeasts and filamentous fungi. Extract and fractions inhibit the in vitro growth of Cryptococcus neoformans, Microsporum gypseum, Trichophyton mentagrophytes and Trichophyton rubrum with a minimal inhibitory concentration range from 62.5 to 500 microg/ml for the extract and from 25 to 100 microg/ml for fractions. A qualitative chemical analysis of the extract and fractions showed the presence of biologically active constituents such as some coumarins, flavonoids, phenols, tannins and sterols. No toxic effect was observed in mice treated per os with the extract. This study provides a scientific confirmation of the use of Chromolaena odorata in traditional medicine.

Animals↗
PubMed2000

Evaluation of antifungal activity of extracts of two Cameroonian rutaceae: Zanthoxylum leprieurii Guill. et Perr. and Zanthoxylum xanthoxyloides Waterm.

Aqueous-ethanol 90% extracts of leaves, roots and stem barks of Zanthoxylum leprieurii and Zanthoxylum xanthoxyloides were examined for their antifungal properties against nine fungi by dilution methods on a solid medium and in a liquid medium. Our results indicate that these extracts, to varying extents, inhibit the in vitro growth of Candida albicans, Cryptococcus neoformans and seven filamentous fungi tested. Only the extracts obtained from the roots and stem barks of Z. xanthoxyloides showed antifungal activity on the germs studied, with minimal inhibitory concentration varying, respectively, from 0.5 to 1 mg/ml for the roots and from 0.125 to 1 mg/ml for the stem barks.

Antifungal Agents↗
PubMed1999

Antifungal activities of seven West African Combretaceae used in traditional medicine.

Seven species of Combretaceae were investigated for their antifungal activity against the pathogenic fungi Candida albicans, Epidermophyton floccosum, Microsporum gypseum, Trichophyton mentagrophytes and Trichophyton rubrum. Pteleopsis suberosa and Terminalia avicennioides appear to be the most active plants. Phytochemical screening shows that these plants are particularly rich in tannins and saponins, which might be responsible for their antifungal activity.

Africa↗
PubMed1999

Mismatch negativity and late auditory evoked potentials in comatose patients.

OBJECTIVES: The purpose of this study was to assess the patterns of mismatch negativity (MMN) and N100 component in comatose patients and to evaluate their prognostic value vis-à-vis return of consciousness. METHODS: MMN and auditory (early, middle-latency and late) evoked potentials were recorded in 52 normals and in 128 comatose patients (comas due to neurosurgical and neurological problems). At the time of recording, all patients scored lower than 8 on the Glasgow scale. RESULTS: Visually detected N100 and MMN were confirmed by cross-correlation of sub-averages. The MMN was present in 33/128 patients and the N100 component in 84/128. The amplitudes of MMN and N100 waves detected in comatose patients were statistically different from those of normal subjects. By 3 months after the onset of coma, 95 patients had returned to consciousness, most of them with moderate to severe disability. A ratio of 30/33 patients with MMN and 70/84 with N100 had regained consciousness. The presence of a MMN together with a N100 component was more specific (90.9%) than the presence of a N100 component irrespective of MMN (57.6%) in terms of predicting return to consciousness, but its sensitivity was lower (respectively 31.6% for MMN and 73.7% for N100). The mean period that elapsed between the recording of evoked potentials and a return to consciousness was 6.3+/-4 days. MLAEPs were also highly specific, but BAEPs were not. CONCLUSION: MMN and auditory evoked potentials provide a reliable assessment of the functional status of comatose patients. When present, MMN and the N100 differ from those found in normal subjects in terms of latencies and amplitudes. As a predictor of return of consciousness MMN had high specificity and low sensitivity, whereas the N100 had high sensitivity and low specificity. This study demonstrates that the recording of MMN and the auditory N100 can be a very useful aid in the assessment of coma and in predicting whether or not a patient will regain consciousness.

Adolescent↗
PubMed1999

[The chondrocranium of an 18 mm human embryo. A 3-dimensional computer-assisted reconstruction].

INTRODUCTION: Three-dimensional reconstruction of histologic structures is still a real challenge. This is the reason why very few specimens are published, especially for the head. MATERIAL AND METHODS: The chondrocranium of an 18-mm human embryo was reconstructed from serial histologic sections. The three-dimensional reconstruction was based on a software used in geology and adapted to medical applications. This software was able to smooth the reconstructed model, i.e. to correct the distortions due to the histologic preparation. RESULTS: The chondrocranium model is presented. To facilitate spatial orientation, we added the reconstruction of Merkel cartilage, of Reichert cartilage, of the vertebrae, and of the cerebrum. The different portions of the chondrocranium are described. DISCUSSION: The three-dimensional result is described and advantageously compared to the rare wax models available. The morphological differences are detailed. CONCLUSION: This technique of three-dimensional reconstruction with its smoothing procedure is a very well adapted method for reconstruction of histologic structures. The results presented confirm the educational value of this tool, which is otherwise a powerful instrument of morphogenic study.

Anatomy, Cross-Sectional↗
PubMed1998

3D reconstruction of the mouse's mesonephros.

The present work reports on the three-dimensional reconstruction of the segmented mesonephros during the embryonic development of the mouse. With a light microscope and an automatic reconstruction of surfaces, aspects of the mesonephros are described. These surfaces are obtained by using digitized contour lines. A new interpolation method called DSI (Discrete Smooth Interpolation) enables correction of the distortion induced by microtomy in paraffin sections. After a triangulation step, this method uses a smoothing algorithm, which implies a spatial redistribution of the vertices of the triangles to correct the rotational and translational misalignment. The use of this 3D program improves the understanding of the development patterns and helps us to appreciate changes in the rebuilt mesonephros. By 10.5 embryonic days, tubules emerge from the Wolffian body and begin their formation, then between 11.5 and 13.5 embryonic days, tortuous mesonephric tubules bound to the Wolffian duct form small curls, which grow and finally unwind. At the same time, mesonephric tubules unbound to the Wolffian duct appear, and on 13.5 embryonic days, the Müllerian duct is visible. After 14.5 embryonic days, the segmented mesonephros keeps its general aspect but decreases in size. At this time, each gonad is provided with both Wolffian and Müllerian ducts. Later, the Wolffian duct differentiates into the definitive male duct system, whilst the Müllerian duct regresses. Conversely, the paramesonephric duct differentiates into the definitive female duct system, whilst the mesonephric duct in turn degenerates. By this time degeneration has begun in the cranial portion of the mesonephros and this process progresses caudally. The spatial organization of the mesonephric tubules and the precise organization of all connections between these elements and the ducts may be well defined. Such approach can allow for a high definition of the normal pattern of mesonephros differentiation.

Animals↗
PubMed1998

Differentiated aspect of female and male mouse mesonephroi.

In the mouse, Sryis expressed by somatic cells in the genital ridge and leads to initiate the transformation of the indifferent gonad into a testis. Here, we have examined the segmented female and male mesonephroi over the developmental period when the initiation of seminiferous cord formation takes place. We have generated three-dimensional models which reveal structural differences between male and female mesonephric tubules at 11.5, 13.5 and 14.5 days post coitum. We evaluate, following structural parameters, that form and orientation of the tubules could evolve differently in both sexes. We propose that the structural organization of the mesonephric tubules presents an early dimorphism.

Animals↗
PubMed1997

Effects of altitude hypoxia on middle latency auditory evoked potentials in humans.

BACKGROUND: This paper presents an investigation of auditory evoked responses in humans subjected to high altitude hypoxic conditions. METHODS: Middle latency (MLAEPs) as well as short latency (BAEPs) evoked potentials were recorded in 10 healthy subjects, first at sea level (N), then 24 h (H1) and 72 h (H3) after their arrival at an altitude of 4350 m. At the same time, arterial blood parameters (PaO2, PaCO2 and pH) were measured and the clinical status of the subjects was assessed. RESULTS: In altitude conditions, the amplitude of BAEP peak V decreased (-17%). The MLAEP waves showed variations in the shape of their latest waveforms. Their amplitudes, however, were not affected. The Pa-Nb interpeak latency significantly decreased (-2.2 ms) between N and H1, and remained stable during the stay at high altitude. CONCLUSION: A correlation was found between the relative decrease of PaCO2 and the shortening of Nb wave latency, suggesting that the variations in MLAEPs could be preferentially related to the ventilatory response of the subjects in hypoxic conditions. However, no correlation was found between the clinical status of the subjects (Acute Mountain Sickness score) and the parameters of the waves.

Adaptation, Physiological↗
PubMed1995

Gamma-range activity evoked by coherent visual stimuli in humans.

We tested the hypothesis of a role of gamma-range synchronized oscillatory activity in visual feature binding by recording evoked potentials from 12 subjects to three stimuli: two coherent ones (a Kanizsa triangle and a real triangle) and a non-coherent one (a Kanizsa triangle in which the inducing disks had been rotated so that no triangle could be perceived). The evoked potentials were analysed by convoluting the signal for each subject and each stimulation type by Gabor wavelets centred from 28 up to 46 Hz, providing a continuous measure of frequency-specific power over time. A first peak of activity was found around 38 Hz and 100 ms with a maximum at electrode Cz in each experimental condition. A second peak of activity occurred around 30 Hz and 230 ms, with a maximum at O1 in response to the real triangle and a maximum at Cz in the case of the illusory triangle. At 100 ms we did not find any variations of the gamma-band component of the evoked potential with stimulation type, but the power of the 30 Hz component of the evoked potential between 210 and 290 ms differed from noise only in the case of a coherent triangle, no matter whether real or illusory. We thus found a 30 Hz component whose power correlates with stimulus coherency, which supports the hypothesis of a functional role of high-frequency synchronization in feature binding.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Auditory selective attention in the human cochlea.

According to current theories, auditory selective attention alters the sensory analysis of acoustic inputs only in the central auditory system. Despite numerous attempts, no evidence of attentional selection has been found in the auditory periphery. Measurements of evoked otoacoustic emissions (EOAEs) during a selective dichotic listening task showed that the EOAEs to tones in one ear had larger amplitude when attention was directed to this ear than when attention was directed to the opposite ear. The results indicate that genuine effects of auditory selective attention can be observed at the cochlear receptor.

Acoustic Stimulation↗
PubMed1991

Laboratory rearing of Phlebotomus perniciosus (Diptera: Psychodidae) and fungal growth problems.

One of the difficulties of growing sandflies in the laboratory is fungal contamination. This study of the laboratory rearing of Phlebotomus perniciosus reports on the nature and circumstances of fungal contamination. Fungal growth is favoured during winter and diapause. The harmful effects vary with the fungal species and the larval stages. The solution to the problem lies on the use of aseptic techniques and the avoidance of overfeeding.

Animal Feed↗
PubMed1990

Candida albicans--adriamycin interactions: ultrastructural and spectrofluorometric study of whole yeasts and spheroplasts.

The occurrence of candidiasis in cancer patients who undergo chemotherapy requires the interrelation of Candida albicans and the antimitotic drug Adriamycin (ADM) which is well known as an intercalating agent. The whole yeasts were not affected by 2 h of contact with the drug at 10(-4) M neither for their growth curve nor for their ultrastructure, despite the presence of free ADM on their surface. Spheroplasts displayed a delay in their growth and exhibited altered nucleoli with segregation of their granular and fibrillar components. The modified emission spectrum of ADM, determined by spectrofluorometry, corresponded neither to the free ADM nor to the DNA-bound drug, but it could be related to a metabolite of the drug. The cell wall appeared to be one of the main sites for ADM resistance of Candida albicans in vitro.

Candida albicans↗
PubMed1990

Brain generators implicated in the processing of auditory stimulus deviance: a topographic event-related potential study.

The neurophysiological mechanisms underlying mismatch negativity (MMN) can be inferred from an examination of some of the brain generators involved in the process of this event-related potential (ERP) component. ERPs were recorded in two studies in which the subjects were involved in a selective dichotic listening task. Subjects were required to silently count rare stimuli deviating in pitch from a sequence of standard stimuli in one ear, while ignoring all the stimuli (standards and deviants) delivered randomly to the other ear. The results showed that, in all cases, the negative wave elicited by the deviant stimuli showed the highest amplitudes over the right hemiscalp irrespective of the ear of stimulation or the direction of attention. Scalp radial current density analysis showed that this asymmetric potential distribution could be attributed to the sum of activities of two sets of neural generators: one temporal, located in the vicinity of the primary auditory cortex, predominantly activated in the hemisphere contralateral to the ear of stimulation, and the other frontal, involving mainly the right hemisphere. The results are discussed in light of Näätänen's model: we suggest the dissociation of two functional processes on the basis of activity of distinct brain areas: a sensory memory mechanism related to the temporal generators, and an automatic attention-switching process related to the frontal generators.

Adult↗
PubMed1990

[Intercommunication psychiatry in a burn center].

The support of psychiatric disorders in a burn centre has been effected since three years, in Saint Luc Hospital (Lyon) thanks to a liaison group. One hour a week, several cases of patients are approached in this group which gathers two psychiatrists and the team dealing with burnt patients. Psychiatrists are attached to clarify the relation between people who attend and patients, to give a diagnosis and propose a strategy in front of difficulties they meet. The psychiatric care is reintegrated in the somatic support and assured by people who are daily effectively in contact with patients. This paper describes the advantages of the liaison psychiatry with regard to a direct intervention of the psychiatrist on the patient. It defines the targets these therapeutic weapon can aim and details the obtained results: for 3 years, the group has met 104 times for 241 "indirect consultations" concerning 99 different patients and count 50 good results on site and 5 specialized orientations; 10 deaths and 11 quick departures exclude 21 patients from the study; 17 cases have been stayed without continuation and 6 without any change.

Burn Units↗
PubMed1989

Diurnal variations of acute mountain sickness, colour vision, and plasma cortisol and ACTH at high altitude.

Time dependence of colour vision in the green/red axis, signs of acute mountain sickness (AMS), and plasma cortisol and ACTH concentrations were studied in eight sea-level male natives exposed 79 h to altitude hypoxia at 4,350 m. Colour vision (CV) was explored every 2 h from 08:00 to 20:00 hours by means of two portable anomaloscopes, one derived from Essilor CHROMOTEST and the other from the OSCAR. Significant diurnal variations in CV were found using both anomaloscopes, major alterations in green relative to red sensitivity being seen in the early morning. AMS scores also showed remarkable diurnal variations, parallel to those of plasma cortisol and CV, with maximum values observed at 08:00 hours. Cortisol diurnal rhythm was maintained in hypoxia, with mean concentrations higher than in normoxia. ACTH followed the same trend, but variations were not significant. Significant correlations were found between instant values of CV, cortisol, and AMS score, but no causal relationship between these variables can be ascertained.

Adrenocorticotropic Hormone↗
PubMed1987

Action of chlorhexidine on budding Candida albicans: scanning and transmission electron microscopic study.

Chlorhexidine is widely used as a bacterial drug whose method of action has been well described in bacteria. Its fungicidal properties have been proved. We show here the effects of a sublethal dose of a preparation of digluconate of chlorhexidine on budding Candida albicans. A fungistatic action is revealed by a decrease in the percentage of budding cells, and two main types of alterations can be observed with transmission electron microscopy (T.E.M.): a loss of cytoplasmic components and a coagulation of nucleoproteins. With scanning electron microscopy (S.E.M.), the cell walls show morphological modifications.

Candida albicans↗