PubMed Health⌕ Search

Biomedical subjects

A Gaillard

Publications and source records attributed to A Gaillard.

At least 19 recordsLinked to original sources
PubMed2004

Fetal cortical allografts project massively through the adult cortex.

Allogeneic embryonic CNS tissue grafts placed in the mature brain are classically considered to lack significant long-range efferents. This problem was reexamined using 'green' cells from mice expressing ubiquitously an 'enhanced' green fluorescent protein as an alternative to classical tract tracing methods. The present study shows that fetal cortical neurons (E15; occipital origin) grafted in the occipitoparietal region of the adult cortex project massively throughout ipsilateral telencephalic structures. Two out of the nine grafted subjects had additional but sparse efferents in the visual thalamus, superior colliculus and pons.

Animals↗
PubMed2003

Co-digestion of concentrated black water and kitchen refuse in an accumulation system within the DESAR (decentralized sanitation and reuse) concept.

Co-digestion of concentrated black water and kitchen refuse within the DESAR concept was the objective of this pilot research. The digestion took place in two, non-mixed accumulation reactors (AC1 and AC2) inoculated with digested primary sludge from a WWTP at a temperature of 20 degrees C for a period of around 150 days. Reactor AC1 was fed with a mixture of faeces, urine and kitchen refuse in the equivalent amount that one individual generates per day. The AC2 was fed with a mixture of faeces and kitchen refuse in the equivalent amount that two individuals produce per day. Some contribution of urine to AC2 was not to be avoided. Detailed characterisation of waste(water) was performed. The performance of the stratified reactor was followed by monitoring the reactor content for several reactors' heights as well as being based on the biogas production. In general the system exposed good process stability. The methanisation of 34 and 61% was obtained for AC1 and AC2 respectively. The biogas yield was 26.5 and 50.8 L/p/d for the respective reactors. Proper choice of inoculum as well as good buffering capacity did not lead to accumulation of VFA and an inhibitive effect due to relatively high ammonium concentration. The chosen process is a promising technology showing good process stability especially for high strength influent.

Bacteria, Anaerobic↗
PubMed2001

Attraction exerted in vivo by grafts of embryonic neocortex on developing thalamic axons.

In a previous study we provided evidence that embryonic (E) day 16 frontal cortical cells grafted into the occipital cortex of newborn rats receive inputs from the ventrolateral (VL) and ventromedial (VM) thalamic nuclei which, normally, project to the frontal cortex (25). The present study was designed to examine further the conditions of development of the thalamic innervation of heterotopic neocortical grafts. We demonstrate that VL/VM axons do not provide transitory aberrant input to the occipital cortex either in intact newborn animals or in rats having received neonatal occipital lesion and subsequent graft of E16 occipital cells. These findings indicate, therefore, that the VL/VM projection to the graft does not result from the stabilization of an initial widespread cortical projection from these thalamic nuclei occurring either spontaneously or in response to the lesion and homotopic transplantation procedures. We also show that the VL/VM projection to frontal-to-occipital grafts develops within a few days posttransplantation and is maintained in adulthood. Finally, this study establishes that most VL/VM axons which enter the grafts are not collaterals of thalamofrontal axons. After having reached the cortex, they proceed caudally primarily within the infragranular layers. The findings of this and previous (25) in vivo studies for the first time provide evidence that developing thalamic axons have the capacity to respond to signals from grafts of E16 cortical cells and are capable of deviating their trajectory to establish contact with the grafts. Only those axons arising from thalamic nuclei appropriate for the cortical locus of origin of the grafted cells respond to the guidance signals. The mechanisms by which the thalamic axons find their way to the graft probably rely on cell-contact signaling and/or long-range attraction exerted by diffusible molecules.

Animals↗
PubMed2000

Laminar distribution of isocortical neurons projecting to occipital grafts in neonate and adult rats.

Physiologically responsive grafts of embryonic (E16) occipital neurons placed into the visual cortex of adult rats were shown previously (Gaillard et al., 1998, Restor. Neurol. Neurosci. 12: 13-25) to receive a predominant (93-97%) cortical input from the infragranular layers V-VI. The present paper examines whether this specific pattern of connections is related to some process of maturation of the host cortex. Pieces of embryonic (E16) occipital cortical tissue were grafted into the visual cortex of neonate (P0), 1-week-old (P7), and adult (P120) subjects. Four months later, graft responsiveness was assessed through field potential recordings and host-to-graft afferents were labeled with a retrograde tracer (cholera toxin subunit B). The data show first that afferents to physiologically active grafts originate about equally from both supra- and infragranular cortical layers in newborn subjects and second that supragranular neurons contribute only 20 and 1.5% of these inputs in P7 and P120 recipients, respectively. This strong upside-down laminar shift of afferents may correlate with the layout of subsets of host neurons that at a given developmental stage would have the intrinsic capacity to regrow an axon. Substantial axogenesis and synaptic stabilization of host-to-graft cortical afferents appear possible only within the critical period for the supragranular neurons but may occur throughout life for the infragranular neurons.

Age Factors↗
PubMed2000

Stage of specification of the spinal cord and tectal projections from cortical grafts.

In order to determine the embryonic age at which the hodological phenotype developed by neocortical cells is specified, we have examined the spinal or tectal projections developed by embryonic (E) grafts of presumptive frontal or occipital neocortex placed into the frontal or occipital neocortex of newborn host rats. Grafts of E13, E14 and E16 cells of the frontal cortex transplanted into the occipital cortex of newborns are capable of developing and maintaining in adulthood a spinal cord axon. Grafts of E12 cells do not project to the spinal cord but send fibres to the superficial layers of the tectum. In addition, following transplantation into the frontal cortex, early embryonic (E12) cells from the presumptive occipital cortex are capable of differentiating into neurons with spinal cord projection but are practically incapable of developing a tectal projection. When grafted at E14 into the frontal cortex, occipital cells lose the capacity to project to the spinal cord but become able to send fibres to the tectum. Taken together, these findings indicate that young (E12) embryonic frontal and occipital cortical cells are competent to subsequently differentiate into neurons projecting to the spinal cord or tectum according to instructive signals available in the cortical territory where they complete their development. By E13/E14, some cortical cells are specified and their capacity to contact targets that are not appropriate to their embryonic origin is much reduced. These findings are consistent with the notion that cortical specification involves progressive restriction in cell multipotentiality and fate specification toward region-specific phenotypes.

Animals↗
PubMed2000

Early commitment of embryonic neocortical cells to develop area-specific thalamic connections.

In this study we examined the thalamic connectivity developed by grafts of embryonic (E16) parietal or occipital cortex placed homo- or heterotopically into the neocortex of newborn rats. We also examined the cytoarchitectonic organization developed by the grafts. Our findings indicate that E16 parietal cortex grafted into the parietal cortex of newborn recipients develops reciprocal connections with the host thalamic ventrobasal complex (VB) but does not establish connections with the host dorsal lateral geniculate nucleus (DLG). When implanted into the occipital cortex, these grafts are still able to establish connections with the VB. In contrast, E16 occipital cortex grafted into the parietal cortex establishes only a few connections with the VB. These grafts are, however, able to develop a substantial system of connections with the host DLG. At 16 days of embryonic age, graft cells are committed to establish thalamic connections appropriate to their tangential locus of origin. In addition, our results show that E16 parietal or occipital cortical cells do not possess the capacity to differentiate and maintain barrel organization even though they are grafted into the terminal field of developing VB axons.

Animals↗
PubMed1999

Transplants of fetal frontal cortex grafted into the occipital cortex of newborn rats receive a substantial thalamic input from nuclei normally projecting to the frontal cortex.

A number of molecular and hodological experiments have provided evidence that there is an early commitment of neocortical neurons to express features unique to a certain cortical area. However, the findings of several transplantation experiments have indicated that late embryonic cortical tissue heterotopically grafted into the neocortex of newborn rats receives a set of thalamic projections appropriate for the host cortical locus within which it develops. To provide further information on the extent to which neocortical neurons are predetermined to develop area-specific systems of connections, in this study we have compared the pattern of thalamic afferents to grafts of embryonic day 16 occipital or frontal neocortex transplanted into the occipital cortex of newborn rats. Two months after grafting, a retrograde neurotracer (cholera toxin, subunit b) was injected into the grafts to precisely assess the number of cells in the visual- and/or motor-related nuclei of the host thalamus projecting to each category of transplants (occipital-to-occipital or frontal-to-occipital). Transplants of embryonic occipital cortex received significant input from several visual-related thalamic nuclei, i.e. the lateral posterior and lateral dorsal nuclei, and no input from motor-related thalamic nuclei. However, only few labeled cells were found in the dorsal lateral geniculate nucleus, which was systematically affected by a severe atrophy, probably in response to the lesion of the occipital cortex performed prior to the transplantation. By comparison, transplants of frontal origin received a substantial input from the ventrolateral and ventromedial thalamic nuclei, which normally project to the frontal cortex, but received a weak input from the lateral posterior and lateral dorsal nuclei. Neocortical neurons grafted heterotopically into the neocortex of newborn hosts are not only able to contact cortical and subcortical targets appropriate for their embryonic site of origin, but are also susceptible to derive thalamic inputs closely related to their embryonic origin.

Animals↗
PubMed1998

Specific invasion of occipital-to-frontal neocortical grafts by axons from the lateral posterior thalamic nucleus consecutive to neonatal lesion of the rat occipital cortex.

Previous work found that transplants of embryonic (E) day 16 occipital cortex placed into the frontal cortex of newborn hosts failed to receive input from visual-related nuclei of the host thalamus. The present study is aimed at determining the possible causes of the lack of visual-related thalamic input to these transplants. For that purpose, a retrograde neurotracer was injected into transplants of embryonic (E16) occipital origin which were placed into the frontal cortex of newborn rats with either intact or damaged occipital cortex. In rats with intact occipital cortex, occipital-to-frontal transplants were indeed not contacted by axons from the dorsal lateral geniculate (DLG) nucleus and received only sparse to negligible input from, respectively, the lateral posterior (LP) and laterodorsal (LD) thalamic nuclei. Yet, following neonatal lesion of the host occipital cortex, the occipital-to-frontal transplants received a significant input from the LP and to a much lesser degree from the LD but practically none from the DLG. Additional control cases with frontal-to-frontal transplants and prior lesion of the occipital cortex did not receive significant input from any of these thalamic nuclei. Thus, following neonatal deprivation of cortical target cells in their main terminal field, LP and to a lesser extent LD axons have the capacity to recognize and significantly innervate appropriate targets even those at some distance from their normal terminal site. DLG neurons degenerate or are not able to contact and invade available terminal space that is provided at some distance from the occipital cortex.

Animals↗
PubMed1998

Neocortical grafting to newborn and adult rats: developmental, anatomical and functional aspects.

This report presents the results of neural transplantation experiments that were designed either to study neural developmental phenomena or to appraise the possible restorative capacity of grafts. The first part of the report deals with the findings of transplantation studies that were performed in newborn recipient rats in an attempt to determine the importance of extrinsic or intrinsic factors in the process of areal cortical differentiation. More precisely, we examined the extent to which extrinsic signals drive the pattern of efferent connections of neurons residing in different cortical areas. In the first experiment, we examined the general distribution pattern of efferents arising from homotopic as compared to heterotopic transplants of embryonic cortical tissue placed into the frontal cortex of newborn rats. Our findings indicated that embryonic occipital neurons transplanted heterotopically into the sensorimotor cortex: (a) only rarely contacted normal targets of the motor cortex, (b) systematically projected towards normal targets of the visual cortex, and (c) distributed fibers to structures normally receiving fibers from both the motor and visual cortex, either exclusively into the visual corticorecipient zone of the structure or into both the visual and motor corticorecipient zones. In the second experiment, we attempted to assess the densities of the spinal projections arising from homotopic or heterotopic transplants implanted into the frontal or occipital cortex of newborn rats. We provided evidence that transplants of embryonic neocortical neurons of frontal origin developed and maintained a spinal cord projection whatever their rostrocaudal position within the host neocortex, whereas transplants of occipital origin did not maintain a significant spinal cord projection in adulthood. Finally, in the third experiment, we analyzed the laminar and tangential distribution of the tectal projections developed by transplants of embryonic occipital cortex placed into the primary or secondary subdivisions of the occipital cortex of newborn rats. Abnormalities in the laminar and/or tangential organization of the tectal distribution of the transplant efferents were systematically found. Using these different transplantation paradigms, we provided increasing evidence that, in their heterotopic location, the embryonic neurons retain some of the developmental characteristics corresponding to their embryonic cortical site of origin. Our findings strongly suggested, therefore, that there is an early specification of neocortical neurons to develop area-specific efferents. In conclusion, converging lines of evidence suggest that regional differences in the neuroepithelium are predetermined early in development, thus leading to cerebral cortex parcellation, as hypothesized by Rakic (1988). In the second part of the report, we describe the results of a series of experiments dealing with the consequences of grafting embryonic cortex into the damaged cortex of adult rats. These effects were examined from an anatomical, metabolic, behavioral, and electrophysiological point of views. The experiments were conducted using either the frontal or the visual cortex as models to appraise the functional integration of the grafts into the motor or visual circuits, respectively. The first study was undertaken to examine the capacity of transplants of embryonic frontal neocortical tissue placed into the frontal cortex of an adult recipient to develop efferents into the host CNS. The results indicated that transplants of fetal neocortex placed into adult CNS had the capacity to develop efferents which seemed to grow over significant distances within the host corpus callosum but, in most cases, failed to penetrate deeply into the gray matter. The density of the efferent projections was, however, far weaker than that seen in newborn hosts. In the second study, the 2-deoxyglucose (2-DG) technique was used to examine the functional integration of hom

Age Factors↗
PubMed1998

High incidence of anti-heparin/platelet factor 4 antibodies after cardiopulmonary bypass surgery.

Fifty-one patients undergoing cardiopulmonary bypass (CPB) were studied on day 0 and day 8 for heparin-induced thrombocytopenia (HIT). The platelet aggregation test (PAT) and tests for anti-heparin-platelet factor 4 (anti-H.PF4), anti-IL8 and anti-neutrophil activating peptide 2 (anti-NAP2) antibodies (Ab) were performed by ELISA. On day 8, 27% of patients were positive for anti-H.PF4Ab. None of these results were found to influence thrombotic complications or platelet counts after CPB. Our results suggest that IgG to H.PF4 may be considered a risk factor, but that additional factors must be required for HIT to develop. We conclude that assays based on platelet activation would be more appropriate for the diagnosis of HIT after CPB.

Adult↗
PubMed1997

Abnormalities in the development of the tectal projection from transplants of embryonic occipital cortex placed in the damaged occipital cortex of newborn rats.

We have examined the degree of precision in the topographic arrangement of the tectal projection developed by homotopic transplants of embryonic occipital cortex and tried to determine whether the development of the corticotectal projection is exclusively dependent on environmental cues or is also controlled by intrinsic factors. Transplants of embryonic (E16) occipital cortex were grafted into various areas of the occipital cortex (Oc1 or Oc2) of newborn rats and the organization of the tectal projection arising from the transplants was subsequently examined by injecting different neurotracers into the transplants. Our results indicate that in most cases the laminar and tangential distributions of the tectal projections from the transplants were abnormal. Indeed, whatever the location of the transplant in the host occipital cortex and whatever the placement of the injection into the transplant, a hybrid distribution of the tectal labeling was found, reminiscent of the pattern observed following tracer deposits in both Oc1 and Oc2 in intact animals. Since the grafts were composed of cells of both Oc1 and Oc2 embryonic origin, it is likely that the hybrid pattern of efferents reflects the heterogeneity of the embryonic origin of the cells composing the graft. These findings provide evidence that the development of the topographic distribution of neocortical efferents is not only dependent on factors extrinsic to the cortex and further indicate that even within one single cortical region, the occipital cortex, different areas (Oc1 vs Oc2) are not totally interchangeable. These findings might have important implications in transplantation experiments aiming at the reconstruction of damaged neocortical circuitry where a precise "point-to-point" reconstruction of the circuitry is expected.

Animals↗
PubMed1997

Risk of early controlateral carotid endarterectomy.

Between January 1984 and January 1994, we performed early endarterectomy of the controlateral carotid on 94 patients within a delay of 1 to 8 days after the first endarterectomy. Lesions were symptomatic in 58 patients (62%) and asymptomatic in 36 patients (38%). Eighty-four operations were performed under cervical block anesthesia (89%), eight under general anesthesia, and two under local anesthesia (2%). Severe intraoperative hypertension occurred in seven patients (7%) including five under cervical block anesthesia (6%) and two under general anesthesia (25%). Two patients (2.1%) died of stroke secondary to carotid thrombosis in one case and hyperperfusion syndrome in one case. Morbidity included one transient ischemic attack (1%) and one myocardial infarction (1%). Postoperative control of patency revealed asymptomatic occlusion of the internal carotid artery in two patients, accounting for one of the two deaths. Our findings demonstrate that neurologic mortality/morbidity is not higher after early controlateral carotid endarterectomy than unilateral endarterectomy.

Aged↗
PubMed1997

[Estimation of the treatment cost of cervical cancer].

BACKGROUND: The goal of this study was to estimate direct costs induced by the first year of treatment of cervix cancers according to the stage at diagnosis. METHODS: Fifteen patients of the Gynaecology Department of the Besançon hospital (Doubs, France) were involved in a prospective study to estimate the real cost of treatment of carcinomas in situ (CIS) by conization and of microinvasive carcinomas (MIC) by simple hysterectomy. Costs of invasive cancers were obtained from a retrospective analysis of 24 hospital records in the Radiotherapy Department. RESULTS: The average real cost of treatment for the CIS was 5023 FF (1995 French Francs). Real treatment cost of the MIC was 15,867 FF. The average cost of treatment for the IB and IIA cancers stage (FIGO classification) was 61,540 FF and 145,314 FF for the IIB to IV stage cancers. CONCLUSIONS: Cost-estimation of cervix cancer treatment according to the stage of diagnosis has to be done before starting a cost-effectiveness analysis of mass screening for cervix cancers. This study will allow us to take into account changes in the stages distribution following on a screening campaign.

Carcinoma in Situ↗
PubMed1993

[Our experience using free vascularized bone flaps in mandibular reconstruction. The external brachial flap, the fibular flap, the para-scapular flap].

New techniques developed over the last decade use vascularized bone flaps for maxillofacial reconstructive surgery. Indications for use of three recently described flaps (external brachial, fibular, parascapular) are discussed as a function of the regions to be reconstructed. Three clinical cases are presented, each patient having received one type of flap.

Adult↗
PubMed1992

[Orofacial dyskinesia. A current pathology].

Bucco-facial dyskinesia is particularly frequent in aged persons, for whom the condition is a definite handicap because of its social and, sometimes, functional impact. The etiology of these abnormal movements is variable. On one hand, many treatments can be incriminated, especially neuroleptics, and on the other hand, there also are frequent spontaneous dyskinesias, movements for which the risk factors are described. The physiopathology remains open to discussion and research, but we already know that the regulation of the nigro-striated pathway plays a role in it, as well, maybe, as toxic (free radicals) and immunological factors. Various therapies are described, but the outcome for such dyskinesias is often unfavorable, at least in elderly subjects, hence the merits of prevention. The latter is based on the prescription of as few neuroleptic drugs as possible, on the use of possibly protective substances, and finally on the suppression on the triggering elements that some local factors may form.

Aged↗
PubMed1992

[Carcinoma of the oral cavity independent of tobacco and alcoholic beverages. Apropos of 23 cases in elderly persons].

Twenty-three cases of carcinomas of the buccal cavity have been observed and treated in persons aged more than 60 years, for whom tobacco and alcoholic drinks, the usual factors of these carcinomas, were not involved. The result of these treatments indicates that the vital and functional prognosis is relatively favorable in these persons, who are free from any alcohol- or tobacco-induced affections.

Aged↗
PubMed1992

[Respiratory pathology of sleep and the upper airways].

Respiratory disorders in the upper respiratory tract during sleep are most often part of a continuous pathological process of long standing. Schematically, three clinical syndromes with increasing severity are described: breathing with the mouth open, snoring and the sleep apnea syndrome. These conditions always include a functional maxillofacial perturbation, which may be associated to a constitutional or acquired morphological disorder. Besides the medical approach itself, the treatment sometimes is surgical, always orthopedic. The earlier it is initiated, the more effective, simple and unconstraining it is.

Adult↗