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Biomedical subjects

F Colin

Publications and source records attributed to F Colin.

At least 19 recordsLinked to original sources
PubMed2004

[Myoclonic encephalopathy associated with proton pump inhibitors].

Two men (66 and 73 Years) with a cardiovascular history were hospitalized for rapid onset encephalopathy associated with myoclonia and an extrapyramidal syndrome. On the basis of the French Pharmacovigilance system, this symptomatology has been attributed to the coadministration of a proton pump inhibitor, lansoprazole (15mg/day) with levodopa. Lansoprazole withdrawal led to a normalisation of the situation.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed2002

Mismatch negativity evoked by the McGurk-MacDonald effect: a phonetic representation within short-term memory.

OBJECTIVES: The McGurk-MacDonald illusory percept is obtained by dubbing an incongruent articulatory movement on an auditory phoneme. This type of audiovisual speech perception contributes to the assessment of theories of speech perception. The mismatch negativity (MMN) reflects the detection of a deviant stimulus within the auditory short-term memory and besides an acoustic component, possesses, under certain conditions, a phonetic one. The present study assessed the existence of an MMN evoked by McGurk-MacDonald percepts elicited by audiovisual stimuli with constant auditory components. METHODS: Cortical evoked potentials were recorded using the oddball paradigm on 8 adults in 3 experimental conditions: auditory alone, visual alone and audiovisual stimulation. Obtaining illusory percepts was confirmed in an additional psychophysical condition. RESULTS: The auditory deviant syllables and the audiovisual incongruent syllables elicited a significant MMN at Fz. In the visual condition, no negativity was observed either at Fz, or at O(z). CONCLUSIONS: An MMN can be evoked by visual articulatory deviants, provided they are presented in a suitable auditory context leading to a phonetically significant interaction. The recording of an MMN elicited by illusory McGurk percepts suggests that audiovisual integration mechanisms in speech take place rather early during the perceptual processes.

Acoustic Stimulation↗
PubMed2001

Canopy structure and light interception in Quercus petraea seedlings in relation to light regime and plant density.

Foliage structure was measured on 1- and 2-year-old Quercus petraea (Matt.) Liebl. seedlings grown in 100 or 18% sunlight at a planting density of 2.8 or 25 plants per m(2). A three-dimensional digitizing device was used to acquire the spatial position and orientation of all leaves within the seedlings and of all seedlings within the plot. The data were used to obtain (1) quantitative information on canopy structure, including leaf area index (LAI), seedling leaf area, number of leaves, leaf area density and leaf orientation; and (2) structural information on foliage arrangement from virtual images to estimate light interception by individual seedlings (STAR) and light partitioning among seedlings. During the second year, shading significantly reduced total leaf area and number of leaves but increased individual leaf area. The STAR was greater for seedlings in shade than in full sunlight because of the more horizontal orientation of leaves. Leaf area density was unaffected by the full sun treatments, and changes in leaf area dispersion had no effect on light-interception efficiency. No plant density effect was observed during the first year. During the second year, only the high plant density treatment induced mutual shading between seedlings, resulting in greater competition for light among seedlings in the full sun treatment than in the shade treatment. The small treatment-induced changes in light interception indicate that Q. petraea has low morphological plasticity of foliage structure compared with other species.

Light↗
PubMed2000

Formalin-induced central sensitization in the rat: somatosensory evoked potential data.

Cortical somatosensory evoked potentials were used to measure secondary hyperaesthesia resulting from subcutaneous 1 and 5% formalin in unanesthetized rats with permanently implanted electrodes. Near field responses were evoked by contralateral non-noxious electrical stimulation of the middle third of the tail. 0.05 ml 5% formalin injected subcutaneously at the base of the tail increased the amplitude of P1-N1 a maximum of 158.5+/-10.91% and N2 a maximum of 150.4+/-21.40% compared to controls (P<0.05 and P<0.01). Amplitudes were increased from 5 min after injection to the end of the 70 min test period. The effect of 1% formalin was equivalent to 5% formalin. This increase was prevented by pretreatment with 5 mg/kg ketamine or 5 mg/kg morphine, in agreement with behavioral and electrophysiological data. Cortical somatosensory evoked potentials are objective measures of central sensitization which may usefully complement current behavioral models for the evaluation of analgesic drugs.

Animals↗
PubMed1999

Neuromotor alterations and cerebellar deficits in aged arylsulfatase A-deficient transgenic mice.

Arylsulfatase A (ASA)-deficient (-/-) mice and ASA(+/+) controls were constructed as a transgenic model for the lysosomal storage disease, metachromatic leukodystrophy (MLD). One-year-old ASA(-/-) mice showed impaired rotarod performance and altered walking pattern characterized by a shorter pace, later evolving into more severe ataxia with tremor in 2-year-old mice. Examination of cerebellar histology showed that 2-year-old ASA(-/-) mice have lost most of the calbindin immunoreactivity from their Purkinje cell dendrites and show simplified dendritic architecture. Additionally, ASA-deficient mice lost a substantial proportion of their Purkinje cells. Recordings of unitary potentials and stimulation of climbing fibers on cerebellar slices from 2-year-old mice indicated that, although the main cerebellar synapses seem to be present and functioning physiologically, the climbing fibers of ASA-deficient mice may have enhanced effects on Purkinje cell activity. It is concluded that ambulatory dysfunctions in ASA(-/-) mice might be explained by an imbalance in the consequences of climbing fiber signals upon Purkinje cell activity due to selective neurodegeneration within the cerebellum.

Aging↗
PubMed1996

N-methyl-D-aspartate receptor activation by guanidinosuccinate but not by methylguanidine: behavioural and electrophysiological evidence.

Levels of methylguanidine (MG) and guanidinosuccinate (GSA) are known to be highly increased in uraemic patients. In the present work, the effects of these uraemic guanidino compounds on the excitatory amino acid system were investigated in vivo and in vitro. It was found that convulsions induced by intracerebroventricular GSA injection in mice were antagonized by N-methyl-D-aspartate (NMDA) receptor blockade, whereas those induced by MG were not significantly altered. Application of GSA (between 25 and 10,000 microM) to mouse spinal cord neurones in primary dissociated cell cultures, evoked depolarizing, inward whole-cell currents in a dose-dependent fashion and with reversal potential at 0 mV; MG did not produce such effects. GSA-induced whole-cell currents were caused by NMDA receptor activation since NMDA receptor antagonists (2-amino-5-phosphonovalerate, Mg2+ and ketamine) blocked GSA-evoked whole-cell currents completely and reversibly, whereas co-application of a non-NMDA receptor antagonist (6-cyano-7-nitroquinoxaline-2,3-dione) did not affect GSA-induced current. Evoked field potentials in CA1 region of rat hippocampal slices were completely abolished by GSA, and this effect was antagonized by NMDA receptor blockade. All data were consistent with selective agonist action of GSA upon the NMDA-type glutamate receptor. In view of the results presented here, it should be examined whether NMDA receptors contribute to the neurological complications of renal failure through GSA-induced inappropriate or excessive activation of NMDA receptors.

Animals↗
PubMed1988

[Drug-induced thrombopenias and neutropenias. An in vitro study by the indirect immunofluorescence test].

The sera from 38 patients with suspected drug-induced thrombocytopenia (22) or neutropenia (16) were tested with the indirect immunofluorescence test on platelets or granulocytes for the presence of drug-dependent antibodies. Three drug-induced antibodies with reactivity against platelets and 5 with reactivity against granulocytes were detected. In 3 sera antibodies were found which reacted already with target cells without adding the drug to the test system. These data show that drug-induced blood dyscrasias often have an immunological cause and that in vitro tests can be helpful in detecting the responsible drug. Different mechanisms can be involved. In many sera circulating antibodies were not found, but an immunological mechanism is likely to be involved in some of these cytopenias: the antibody could be entirely absorbed by the target cells, a metabolite of the drug could be the immunogen and finally the test may not be sensitive enough.

Agranulocytosis↗
PubMed1988

Association of breakpoint 14q23 with uterine leiomyoma.

A chromosomal study of short-term cultured tumor cells from a benign uterine leiomyoma showed a clonal insertion, dir ins(14;6)(q23;p23p25) as a unique change. This finding supports the hypothesis of a specific association of the breakpoint 14q23 with uterine leiomyoma.

Chromosome Banding↗
PubMed1987

[Effect of in vitro carbamylation of erythrocytes on their rheological properties].

In order to assess the role of carbamylation of erythrocyte proteins in the modification of rheological parameters of red blood cells observed in uremic patients, and in vitro carbamylation of erythrocytes and hemoglobin was carried out using sodium cyanate. The carbamylation of hemoglobin was determined by observation of the increase of HbA1 fraction. The deformability of erythrocytes and the viscosity of erythrocyte suspensions and of hemolysate were measured. The results showed an increase in the deformability of red blood cells and a decrease in the viscosity of hemoglobin as the carbamylation increased. This is attributed to a decrease of hemoglobin viscosity and to a modification of the electric charge of the membrane. These results show that the reduced erythrocyte deformability observed in patients with renal failure is not due to erythrocyte protein carbamylation.

Adult↗
PubMed1984

[Gougerot-Sjögren syndrome and monoclonal immunoglobulin].

Serum electrophoresis and immunoelectrophoresis were performed in 67 patients with Sjögren's syndrome. We found a monoclonal gammapathy in 11 cases: IgG (10 cases) and IgM (1 case). 1 monoclonal gammapathy was detected in 2 of 21 patients with primary Sjögren's syndrome. All patients with monoclonal gammapathy were asymptomatic.

Adult↗
PubMed1981

[Transfusional malaria in France (1960-1979) (author's transl)].

Transfusional Malaria is not a rare condition in France: in the past 20 years, 110 cases were cited in the literature and/or reported to us in answers to a recent questionnaire. Of these, 24 cases occurred between 1960 and 1969 and 78 between 1970 and 1979. This apparent increase in occurrence in the past decade is most probably due to the increase in the number of transfusions of whole blood or fresh fractions containing infected erythrocytes, although population exchanges with inter-tropical Africa may also play a preponderant role. Our study confirms that Plasmodium falciparum is the most prevalent pathogen responsible for this condition in France; it caused 84% of cases in the past five years. We think this point must be taken in account by the legislator.

Adult↗
PubMed1981

The effect of acute anoxia on the cortical somatosensory evoked potential in the rabbit.

In the course of this study it was found that the functional state of the cortex during anoxic anoxia could be more accurately monitored by the cortical somatosensory evoked potentials (EPs) than by the electrocorticogram (ECoG). Compared with the ECoG, the EPs yield more detailed information. Five different steps may be distinguished in the evolution of EPs; the ECoG, however, exhibits only two (almost trivial) abnormal patterns (epileptic pattern and flat response). Of particular practical interest are the two steps preceding the disappearance of the EPs: (1) a rounding of the P wave accompanied by an increased voltage, followed later by (2) a decrease of the latter. If, at this stage, anoxia is maintained for 20 seconds, then permanent dysfunction is observed, at least during the time interval of the experimentation.

Animals↗