Defining Local Chemical Conditions in Magnetosomes of Magnetotactic Bacteria.

Defining chemical properties of intracellular organelles is necessary to determine their function(s) as well as understand and mimic the reactions they host. However, the small size of bacterial and archaeal microorganisms often prevents defining local intracellular chemical conditions in a similar way to what has been established for eukaryotic organelles. This work proposes to use magnetite (FeO) nanocrystals contained in magnetosome organelles of magnetotactic bacteria as reporters of elemental composition, pH, and redox potential of a hypothetical environment at the site of formation of intracellular magnetite.

Nasal fibroscopy as a routine screening procedure of sinonasal adenocarcinoma of woodworkers: French longitudinal case study.

Background: The purpose of this study was to assess the relevancy of flexible nasoendoscopy as a routine screening procedure of sinonasal adenocarcinoma among people occupationally exposed to wood dust.

Methods: This study included woodworkers, occupationally exposed to wood dust. Evaluations were scheduled at the time of inclusion (T0) and after a 2-year period (T1).

Four major disasters in Aquitaine, France: use of odontologic techniques for identification.

The 4 mass disasters that have affected the Aquitaine region (France) in the previous 15 years are related through the specificity and the efficiency of dental methodology in identifying the victims. The results point to the decisive influence and the efficiency of dental methodology for identification of bodies that are burned or disfigured after an accident or a prolonged period in water.

Evidence for glutamatergic tectotectal neurons in the cat superior colliculus: a comparison with GABAergic tectotectal neurons.

The tectotectal commissural pathway is commonly regarded as responsible for the reciprocal inhibition that takes place between the two superior colliculi (SC). Although this hypothesis has received strong support from electrophysiological studies, more recent investigations have suggested that some collicular cells, e.g.

Hyper- and hypogravity alter posture in rats compensated on Earth for a vestibular asymmetry.

Head posture and neck muscle activity (EMGs) were examined in unilateral (UL) and bilateral (BL) vestibularly lesioned rats in hypergravity (1.7 g) and hypogravity (0 g) during parabolic flights. Compared with BL rats taken as control, the head and the body of UL deviated toward the lesion side at 0 g and toward the intact side at 1.

Rapid, efficient dental identification of 92% of 13 train passengers carbonized during a collision with a petrol tanker.

On September 8, 1997 (day 0), an express train in Aquitaine, France, crashed into a petrol tanker, which immediately burst into flames and set the first carriage of the train on fire. We describe the dental technique and methodology which led (day 2) to the positive identification of 92% of these very heavily carbonized remains. In only 1 case, and only to be totally certain, did the investigators have recourse to use molecular biologic techniques.

Influence of the tectal zone on the distribution of synaptic boutons in the brainstem of goldfish.

This study investigated whether the topographic differences in the functional properties of the tectal motor map of goldfish are related to particular patterns of connections with downstream structures. With this aim, the distribution of synaptic boutons in the mesencephalic and rhombencephalic structures was studied after discrete injections of the tracer biotinylated dextran amine were placed at separate sites along the tectal anteroposterior axis. Irrespective of the location of the injection site, the boutons were more abundant in the mesencephalon than in the rhombencephalon, and they were located chiefly ipsilaterally all throughout the brainstem.

Topographical characteristics of preposito-collicular projections in the cat as revealed by Phaseolus vulgaris-leucoagglutinin technique. A possible organisation underlying temporal-to-spatial transformations.

A neuronal pathway from the nucleus prepositus hypoglossi (PH) to the superior colliculus (SC) has been documented in previous studies using retrogradely transported tracer methods. This pathway may underlie a feedback control of gaze-related collicular activities. The present study provided a detailed description of this pathway in the cat using the Phaseolus vulgaris-leucoagglutinin technique.

Firing properties of preposito-collicular neurones related to horizontal eye movements in the alert cat.

The projection from the nucleus prepositus hypoglossi (PH) to the superior colliculus (SC) has been proposed to provide a feedback control of collicular saccadic activities. The present study aimed to identify the functional properties of PH neurones projecting to the SC relative to eye movement parameters. Preposito-collicular neurones were identified in alert cats by antidromic invasion and collision tests following electrical stimulations of the contralateral SC.

Distribution of synaptic terminals from prepositus neurones on the collicular maps.

The distribution of synaptic terminals was quantified in the superior colliculus (SC) following injections of Phaseolus vulgaris-Leucoagglutinin in the ventral prepositus hypoglossi nucleus (PH) and adjacent reticular formation. Labelled axons distribute terminals within the intermediate and the deep layers on both sides. Within the former, their distribution reproduces the representation of the visual hemifield on the same side as the injected PH.

Continuous ambulatory peritoneal dialysis: evaluation of three new culture methods.

Out of 900 dialysates analysed over 15 months at the Rennes Regional Hospital, 116 cloudy specimens with a leucocyte count of more than 100/mm3 were studied. Three methods of laboratory diagnosis based on physical or chemical disruption of leucocytes were evaluated: saponin incorporated in the agar medium, sonication, and the Isolator lysis centrifugation system. Sensitivity was improved (52%) for the three methods combined compared with the standard method (37%).

Firing behaviour of anticompensatory neurones in the prepositus hypoglossi nucleus of alert cat.

The present results demonstrate that anticompensatory neurones could be recorded within the prepositus hypoglossi nucleus of the alert cat. These neurones, like burster-driving neurones described in paralysed cats, were characterized by a tonic increase of firing for head turning in the contraversive direction (type II) associated to bursts for each vestibular quick phase in the same direction. They were also involved in the generation of visually triggered saccades since they displayed a burst preceding contraversive saccades and a pause in the opposite direction.

Possible excitatory and inhibitory feedback to the superior colliculus: a combined retrograde and immunocytochemical study in the prepositus hypoglossi nucleus of the guinea pig.

We have investigated in the guinea pig the precise localization and the immunoreactivity of the neurones in the prepositus hypoglossi nucleus involved in a direct ascending projection onto the superior colliculus. The projecting neurones were characterized by a retrograde tracer (WGA-ApoHRP coupled to gold particles), injected in the intermediate and deep layers of the superior colliculus. After revealing gold particles, the sections were then treated using an antibody either against GABA or against glutamate, thus allowing identification of gold-filled-immunoreactive neurones.

GABA and non-GABA immunostained neurones in the nucleus prepositus and the periparabigeminal area projecting to the guinea pig superior colliculus.

We have investigated the possibility that GABAergic neurones may be involved in two ascending projections to the superior colliculus, originating in the nucleus prepositus hypoglossi and in the periparabigeminal area of the mesencephalon, respectively. The projecting neurones of both structures were identified using gold-WGA-apoHRP, a retrogradely transported tracer, injected unilaterally into the superior colliculus. GABA was detected in these neurones by means of immunocytochemical staining.

Eye and neck motor signals in periabducens reticular neurons of the alert cat.

The purpose of this work was to search for neurons in the ponto-medullary reticular formation which can carry horizontal eye position signals to dorsal neck muscles of the cat. The recordings were localized in an area of the ponto-medullary reticular formation which contains reticulo-spinal neurons projecting to the neck (Peterson et al. 1980).

Brain stem nuclei giving fibers to lobules VI and VII of the cerebellar vermis.

The HRP method has been used to identify all the brain stem nuclei, which may project to lobule VI and/or VII of the posterior cerebellar vermis. Three tentative degrees of labeling of the different structures have been assigned: 'massive', 'clear' and 'discrete'. (1) Massive projections have been found to reach lobule VI and VII from the inferior olive and lobule VII only from the nucleus reticularis tegmenti pontis.

Perihypoglossal and secondary vestibular projections to lobules VI and VII of the cerebellar cortex: An HRP study.

Horseradish peroxidase (HRP) was injected into (1) lobule VI; (2) lobule VII; (3) lobule VI and VII of the cat's cerebellar vermis. Marked cells were found in two groups of nuclei related to the vestibulo-ocular system; (a) the three perihypoglossal nuclei: praepositus hypoglossi, nucleus of Roller and intercalatus of Staderini and (b) two areas of the secondary vestibular complex located within the medial and the descending vestibular nuclei. It is concluded that fibers from the perihypoglossal and the secondary vestibular nuclei project to both lobule VI and lobule VII of the cerebellar cortex.

[Projections of bulbar reticular nuclei and raphe nuclei to lobules VI and VII of cat cerebellar cortex].

Injections of horseradish peroxidase were made in lobules VI and VII of the cerebellar vermis (in the Cat). Serial frontal sections of the brain stem reveal that the lateral and paramedian nuclei were essentially projected onto lobule VI, and the projections from the raphe nuclei onto lobule VII.

The climbing fibers of the cerebellar cortex, their origin and pathways in cat.

The sources and pathways of the climbing fibers to the cerebellar posterior vermis were studied with comibined electrophysiological and anatomical methods in cats. Recording from identified cerebellar Purkinje cells, monosynaptic climbing fiber (CF) responses have been obtained both for stimulation of the inferior olive (IO) and various parts of the brain stem (BS). CF responses were found to of three types, IO only, BS only or both IO and BS.

Horseradish peroxidase localization of masticatory muscle motoneurons in cat.

Horseradish peroxidase has been injected into individual masticatory muscles in young and adult cats in order to determine the topography of the corresponding groups of motoneurons in the motor nucleus of the Vth nerve. The results obtained show a clear dorsoventral somatotopic distribution; the superior muscles have their motoneurons located dorsally in the nucleus and the inferior muscles ventrally; the two main jaw closers, temporalis and masseter, are represented in the dorsal and central parts of the nucleus; located more ventrally are the motoneurons for the pterygoideus medialis and lateralis, the jaw closers and abductor muscles; finally motoneurons for the jaw openers, and the anterior belly of the digastricus and mylohyoideus, occupy the ventromedial part of the nucleus. All muscles have been found to be represented along the entire length of the nucleus, with the same dorsoventral layering.

Trigeminal representations of the masticatory and extraocular proprioceptors as revealed by horseradish peroxidase retrograde transport.

Horseradish peroxidase has been injected in the masticatory and extraocular muscles in newborn and adult cats to identify the cells of origin for the muscle endings. Labeled motoneurons in the nuclei of the III, IV, V and VI nerves have been observed. They are the parent cells of the motor terminals taking up the enzyme in the muscle injected.

[Uptake and transport of exogenous peroxidase in the masticatory muscles of the cat. Localization of motor neurons].

In the present work, a topographical localization of masticatory muscle motoneurons was undertaken. Horseradish peroxydase injected in each muscle can be transported in the retrograde direction to the corresponding motoneurons cell bodies. Jaw-closing muscle motoneurons were identified in the dorsal part of the motor trigeminal nucleus whereas jaw-opening muscle motoneurons were observed in the ventro-medial region.