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Biomedical subjects

J Calvet

Publications and source records attributed to J Calvet.

At least 19 recordsLinked to original sources
PubMed2005

Induction of acute lung injury after intranasal administration of toxin botulinum a complex.

The inhalation of aerozolized botulinum toxin may represent a potential significant hazard to both military and civilian personnel. Since the lung is the primary target organ for inhaled toxin, the investigation reported herein was conducted to examine lung function in mice exposed to botulinum toxin A complex by intranasal route. Data includes lethality, symptomatology, measurement of respiratory function (minute ventilation, respiratory frequency, and tidal volume), and histopathology of the lungs. The clinical signs of intoxication are similar to those observed in foodborne botulism. Plethysmography revealed severe impairment of all respiratory parameters tested from 7 hours postexposure. Severe lung lesions, possibly secondary to the intoxication, were observed in mice who survived 14 days after the toxin challenge. These included intra-alveolar hemorrhage and interstitial edema. Mice immunized by the pentavalent (ABCDE) toxoid were protected against the neurotoxin (4 LD50) as revealed by the decrease of lethality and severity of nervous signs of intoxication, but not against histopathological changes in the lungs. These effects are nonspecific and require further experiments in order to specify the relationships between the pathology and the inflammatory process in the lung due to mediators such as cytokines,and possibly permanent physiological sequelae.

Administration, Intranasal↗
PubMed2000

Efficient protection of human bronchial epithelial cells against sulfur and nitrogen mustard cytotoxicity using drug combinations.

The aim of this study was to test the efficacy of several candidate molecules against sulfur mustard (SM) and nitrogen mustard (HN2) using a human bronchial-epithelial cell line (16HBE14o-). Candidate molecules were chosen on the basis of the known cytotoxicity mechanisms of mustards or their efficacy previously observed on other cellular models. It included the sulfhydryl-containing molecules N-acetyl-cysteine (NAC) and WR-1065, the nucleophile hexamethylenetetramine (HMT), the energy-level stabilizer niacinamide (NC), the antioxidant dimethylthiourea (DMTU), L-arginine analogues such as L-thiocitrulline (L-TC) and L-nitroarginine methyl ester (L-NAME), and the anti-gelatinase doxycycline (DOX). Their efficacy was determined using 2-(4-[3-iodophenyl)-3-(4-nitrophenyl)-5-(2, 4-disulfophenyl)-2Htetrazolium (WST-1) reduction by viable cells 24 h after initial exposure to 100 microM HN2 or SM. On individual immediate cotreatment, some molecules exhibited selective protection against only one mustard, such as DMTU and WR-1065 against HN2 and DOX against SM, whereas NAC and L-TC were effective against both SM and HN2 cytotoxicity. However, as the level of protection against SM was always weak compared to HN2, several combinations were investigated against SM to improve the protection. The effective combinations (L-TC + DOX, NAC + DOX, NAC + DMTU, NAC + HMT, NC + DOX) combined agents, reducing the bioavailability of the mustard with compounds possibly acting on the consequences of alkylation. One of these combinations, NAC + DOX, appeared to be the most interesting, as these agents are already used in human therapy. It exhibited good efficacy in delayed cotreatment (up to 90 min) against SM.

Acetylcysteine↗
PubMed1996

[Presence of markers predictive of type I pre-diabetes mellitus status in relatives of patients with type I diabetes mellitus].

BACKGROUND: The aim of this study was to analyze the predictive factors of IDDM in first degree relatives of IDDM patients. SUBJECTS AND METHODS: From 1992 to 1994, 1,053 first degree relatives were screened for measuring islet cell antibodies (ICA) by indirect immunofluorescence (iFl). In all ICA positive subjects, beta cell function was analyzed by intravenous glucose tolerance test (IVGTT) and other immunologic parameters were also studied: anti-insulin antibodies (IAA) by radiobinding and antibodies to glutamic acid decarboxylase (GADAb) by ELISA methods. RESULTS: ICA were found in 3.1% of the first degree relatives. IVGTT showed a significant decrease in acute first phase of insulin response to glucose (IRI 1 minute + 3 minute) in those with ICA > or = 20 JDF units. In patients with ICA > or = 20 JDF units, 20% were found to be positive for IAA and 40% were positive for GAdAb. Thirty-one percent (10/32) of ICA positive first degree relatives fulfilled prediabetes criteria. During follow-up, 40% (4/10) of these prediabetic patients developed IDDM. CONCLUSION: This study confirms the possibility of identifying among first degree relatives of IDDM patients the subgroup with high risk of developing IDDM thus allowing the initiation of therapy for preventing or delaying IDDM onset.

Adolescent↗
PubMed1993

Culture model for the study of cerebral malaria: antibodies from Plasmodium falciparum-infected comatose patients inhibit the dendritic development of Purkinje cells.

The in vitro development of kitten Purkinje cells was inhibited by sera or IgG from cerebral malaria (CM) patients but not by sera from acute non-complicated malaria (NCM) cases. This inhibitory effect, quantified by computer-assisted methods, concerned the dendritic (though not the axonal) development and was found to be related to the presence of CM sera of self-reactive antibodies of the IgG class. These results suggest that protection acquired against the major complication of Plasmodium falciparum malaria may correspond to the repression of an abnormal stimulation of autoreactive B cells.

Animals↗
PubMed1993

GABAergic neurons in human spinal cord cultures: a computer-aided analysis of normal and thienyl-phencyclidine-treated cells.

gamma-Aminobutyric acid (GABA)-containing neurons were studied in dissociated cell cultures of human spinal cords from 6-10-week-old fetuses using immunohistochemistry with anti-GABA antibodies. Light microscopy showed two types of immunoreactive (IR) neurons: (1) IR neurons with short neuritic processes remaining near the cell body (small neuritic tree neurons); and (2) IR neurons with long neuritic processes extending far from the cell body (large neuritic tree neurons). Both types were studied at different ages in vitro, in control and in thienyl phencyclidine (TCP)-treated cultures by means of computer reconstructions and morphometric parameters. A discriminant analysis permitted the recognition of three populations: whatever the age, the control and TCP-treated neurons with small neuritic trees were not discriminated from each other and were considered to be one population whereas the 98 DIV control and both 21 DIV and 98 DIV TCP-treated cells with large neuritic trees were clearly separated from each other and from the small cell population. In all models, an astrocytic labeling, weaker than that of the neurons, was observed. The nature of these neurons (probably interneurons) intrinsic to the spinal cord is discussed in view of previous findings concerning the anatomical distribution and organization of the GABAergic system in the spinal cord.

Cells, Cultured↗
PubMed1992

Networks formed by dorsal root ganglion neurites within spinal cord explants: a computer-aided analysis of HRP intracellularly labeled neurons.

Dorsal root ganglion (DRG) neurons from rat embryos were explanted either alone or with the attached spinal cord (SC). Neuritic processes were mapped out histologically using an intracellular iontophoretic HRP method. Computer reconstructions and morphometric parameters allowed a comparative quantitative analysis of the DRG neurons and of their neuritic processes in both models. The first model, strongly dependent on nerve growth factor (NGF) for its survival, developed large multidirectional processes. The second model showed a bipolar distribution of its neuritic processes, the central one entering predominantly the dorsolateral part of the cord explant and ramifying both homo- and heterolaterally. The quantitative data revealed a significant decrease in the overall size of the neuritic networks of the second model (with attached SC). A discriminant analysis permitted the recognition of these two populations of DRG neurons. The role of the spinal cord explant, and more precisely the target cells of the dorsal horn, was considered to be a prominent factor in the development of the DRG neuritic networks.

Animals↗
PubMed1992

Neuronal firing patterns of organotypic rat spinal cord cultures in normal and in ACTH/alpha-MSH(4-10) analog (BIM 22015)-supplemented medium.

The spontaneous and evoked electrical patterns of spinal cord explants from 13- to 14-day old rat fetuses grown from 2 to 8 weeks in vitro were compared when fed either with a standard or with an adrenocorticotropic hormone/alpha-melanocyte stimulating hormone (4-10) analog (BIM 22015)-supplemented medium. Standard and BIM 22015-treated cultures developed similar patterns of extracellularly recorded activity which consisted of mostly phasic but also tonic discharges. The standard cultures when treated by BIM 22015 in acute experiments (100 micrograms/ml) showed a decrease in their frequency of discharges which fired in a regular tonic pattern. These effects were neither age- nor dose-dependent but were increased in Ca2+ free medium. The ventral cord neurons chronically fed with BIM 22015 showed a strongly bursting pattern resembling strychnine-induced synchronized bursts. Both these effects, inhibitory (acute) and excitatory (chronic), of the BIM upon spinal cord cultured ventral horn neurons are discussed as possible calcium-dependent phenomena.

Adrenocorticotropic Hormone↗
PubMed1988

Computer-assisted analysis of the developing Purkinje neuron. I. Effects of the age of the animal at the moment of explantation on the subsequent dendritic development in organotypic cultures.

Purkinje cell dendritic arborization were studied in intracellularly horseradish peroxidase-stained mature neurons grown during 30-40 days in organotypic cerebellar cultures from kittens of various ages. The effects of the age of the animal at the moment of explantation upon the subsequent dendritic and axonal development were studied in kitten cerebella of 1, 12 and 21 postnatal days old. These effects were investigated by computer-assisted methods. Qualitative data were found to be different in these 3 in vitro models explanted at 3 different ages except for the spine development which remained the same. Quantitative data, obtained from 15 measurable parameters, showed that the degree of dendritic development was higher for the Purkinje cells explanted at the latest postnatal age: the older the animal, the larger the dendritic tree in culture. A discrimination analysis permitted a recognition of the 3 differently aged populations (94% well classified cells) based on 3 selected variables, number of primary dendritic trunks, number of rows and dendritic field areas. These results lend further support to the major role played in the final dendritic arrangement by extrinsic (discriminant factors, their pre-existence in vivo being responsible for the subsequent degree of the in vitro development of the Purkinje cell dendritic arbor.

Aging↗
PubMed1988

Computer-assisted analysis of the developing Purkinje neuron. II. A comparative study of the dendritic development in differently aged kittens and in organotypic cultures explanted at the same ages.

Golgi-prepared cerebella from 10-13-(model K) and 22-day-old (model C) kittens were analyzed and compared with 30-40 days in vitro (DIV) horseradish peroxidase (HRP)-stained organotypic cultures from kitten cerebella explanted at comparable ages (12 (model E) and 21 (model T) postnatal days). In addition, HRP-stained cerebella explanted from 1-day-old kittens were used as a reference (model N). Computer reconstructions and morphometric parameters (14 variables) allowed a comparative quantitative analysis of the Purkinje cell dendritic trees and axonal processes. The biplanar arrangement of the dendritic sheets observed in vivo at 10-13 days (K) was replaced by a mostly bipolar one in the in vitro Purkinje cells (E) explanted at the same age with their axon following the direction of either dendrite. The dendritic expansion observed in intact animals between 12 and 22 days was mostly due to an increase in the number of dendritic segments having shorter lengths rather than an increase in the number of rows. A discriminant analysis permitting the recognition of 3 populations of Purkinje cells in both groups reinforced the previous hypothesis that the dendritic shapes are modelled by specific afferents pre-existent in vivo.

Aging↗
PubMed1987

[Electrophysiology and analysis of the image of the development of Purkinje cells in culture and in the intact animal].

The electrophysiological and morphological properties of the Purkinje cells (P cells) grown in organotypic cultures were studied in HRP intracellulary labelled neurons and compared to Golgi stained P cells from kitten of different ages. The effects of afferent fiber depletions on the final dendritic topological parameters were investigated by 3-dimensional reconstructions and computerized methods. In culture, the P cell dendritic trees always appeared reduced in size when compared to their in vivo counterparts. A discriminant analysis permitted the recognition of 3 populations of cultured P cells according to the type of deafferentation. In intact animals, the dendritic organization appeared biplanar around day 13. These results demonstrate that the presence of all normal inputs is required to achieve the full elaboration and the monoplanar disposition of the P cell dendrites.

Aging↗
PubMed1985

Morphologic and functional abnormalities that develop in kitten Purkinje neurons during maintenance for months after maturation in organotypic cultures.

The morphologic and functional properties of the Purkinje cells (P-cells) grown for 10-11 weeks in organotypic cultures from newborn kitten cerebella were studied and compared to cultures which had been grown for 4-5 weeks under the same standard conditions. Electrophysiological and morphological data were obtained from HRP iontophoretically labeled neurons and were quantified by means of computerized techniques. Extracellular recordings of spontaneous activity showed that the 10-11-week-old P-cells had a pacemaker-like firing rate whereas the P-cells aged 4-5 weeks in vitro displayed a bursting activity. The qualitative morphological data evidenced abnormal swellings both on dendritic and axonal processes of the 10-11-week-old P-cells which were not present on the 4-5-week-old P-cells. The quantitative data revealed a significant decrease in the overall size of the dendritic network of the 10-11-week-old P-cells mainly due to a reduction in the total dendritic length and in the total number of dendritic segments, whereas the individual segment lengths remained almost unchanged. Dendritic spine counts showed no decrease in the dendritic density of these older P-cells. Such data suggest that the changes observed in 10-11-week-old cultured P-cells may be compared to the age-related changes occurring in vivo and that such in vitro models could be useful tools in the study of the pathology of aging. However, alternative factors other than senescence are discussed since they may account for some degenerative changes observed in the older cultured P-cells.

Animals↗
PubMed1985

Sodium butyrate-induced changes in cultured rabbit articular chondrocyte transmembrane electrical potentials. Relationship between these changes and the proliferative response.

Sodium butyrate at 5mM reversibly induced a significant increase of transmembrane potentials (Em) in normal chondrocytes (24 hours after seeding) and arrested their proliferation. This increase in Em levels, which could be temporarily abolished by Tetra-ethyl Ammonium (TEA 5mM), was related to an increase in membrane permeability to K+. This hyperpolarization was correlated with the reversible inhibition of growth in G1 induced by the sodium butyrate.

Animals↗
PubMed1985

The Purkinje cell dendritic tree: a computer-aided study of its development in the cat and in culture.

Golgi-prepared cerebella from 1, 10, 13 and 30-day-old kittens were analyzed and compared with 30-45 days in vitro (DIV) HRP-stained organotypic cultures of newborn kitten cerebella. Computer reconstructions and morphometric parameters allowed a quantitative analysis of the Purkinje cell (P-cell) dendritic trees. In intact animals the dendritic organization appeared monoplanar as early as one day after birth and biplanar in 85% of the cells at day 13; however, by day 30, 90% of the cells were monoplanar. During the first 4 postnatal weeks, the dendritic expansion was due mostly to an increase in the total number of segments and the total dendritic length, whereas the overall mean segment length remained almost unchanged. In culture, the 30-45 DIV P-cell dendritic trees always appeared reduced in size when compared to their in vivo counterparts due mostly to a reduction in the total number of segments. Nevertheless, these cells retained several primary dendritic trunks and their overall mean segment length was longer. These supposedly 'mature' cultured P-cells never reached full adult development: a discriminant analysis classified them as resembling those from intact animals of 13 days but often maintaining some properties of newborn animals. These results demonstrate that the presence of all normal inputs is required to achieve the full elaboration and the planar disposition of the P-cell dendrites.

Animals↗
PubMed1983

The dendritic trees of Purkinje cells: a computer assisted analysis of HRP labeled neurons in organotypic cultures of kitten cerebellum.

Purkinje cell dendritic arborizations were studied in HRP intracellularly stained mature neurons grown during 30-50 days in organotypic cerebellar cultures from newborn kittens. The effects of afferent fiber depletions on the final dendritic topological parameters were investigated by computer assisted methods. Three differently deafferented models lacking both parallel and climbing fibers (PF and CF), only PF or only CF were thus studied. Qualitative data were found to be common to these 3 in vitro models and similar to those following other in vivo deafferenting procedures. Quantitative data obtained from 16 measurable parameters showed that all dendritic trees were markedly reduced in size as indicated by a decrease in total dendritic length and total number of segments although in all models individual segment lengths remained largely unaltered. A discriminant analysis permitted the recognition of 3 populations (100% well classified cells) based on 3 selected variables: dendritic field area, mean path length and total number of segments (with the lowest values for the model lacking only PF). These results are shown to lend further support to the role played in the final dendritic arrangement by both intrinsic (non-discriminant) and extrinsic (discriminant) factors and more precisely by the two distinct specific afferent systems (PF and CF).

Afferent Pathways↗
PubMed1983

Evolution of myoelectrical and precentral cell activities during learning of a new amplitude of movement.

The object of these experiments was to determine if changes in precentral neuron activity may be related to learning of a new amplitude of movement. Data were obtained from two monkeys trained to stop, in a given position, an elbow flexion movement in order to get a reward. A screen prevented the animal from seeing its forearm. The terminal position was not indicated by a cue, and movements were self-initiated. Motor performance and cell activity were analyzed during the period of learning of a new amplitude of movement. The cells studied presented the reciprocal patterns of activity: they were active flexion but discharged during passive extension. Results clearly indicated that: (1) amplitude was the actual parameter which was learned; (2) the peak frequency of discharge of motor cortex neurons increased during learning, as did the frequency of reward; and (3) the peak frequency of discharge related to passive movements was not changed by conditioning. The results support the hypothesis that the increase of the activity tied to active movements which is observed during conditioning may not be related to an increase of peripheral feedback but expresses a greater 'corticalization' of the movement.

Animals↗