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Biomedical subjects

M Imbert

Publications and source records attributed to M Imbert.

At least 55 records · Page 3Linked to original sources
PubMed1992

Myelodysplastic syndromes (MDS) and acute myeloid leukemias (AML) with myelofibrosis.

Acute myeloid leukemias (AML) and myelodysplastic syndromes (MDS) enter rarely in the differential diagnosis of myelofibrosis (MF). MF of marked intensity, resulting in either "dry taps" or non-representative smears, is encountered in approximately 10% of cases. MF may be observed in any type of AML, most frequently in acute megakaryoblastic leukemia (M7). Apart from some typical cases of MDS, MF is associated with cases of acute myelodysplasia with myelofibrosis (and a major megakaryocytic component). This syndrome has been described under various headings: acute or malignant myelosclerosis, and acute MF. It should be distinguished from M7 and from myeloproliferative syndromes.

Acute Disease↗
PubMed1992

[Cholecystectomy by celioscopy. Experience in two Upper Normandy hospital units. Apropos of 178 procedures].

Laparoscopic cholecystectomy (LC) emerges as an effective alternative to classical cholecystectomy, but its safety, benefits and indications still need to be clarified. From September 1989 to March 1991, 178 LC were performed by 8 surgeons in 2 hospitals, on 142 women and 36 men with a mean age of 48.2 years. The gall bladder wall was thin in 160 cases and thick in 18 cases (with 6 cases acute cholecystitis). We observed no deaths, 147 simple procedures with a hospital stay and drug requirement lower than with the usual cholecystectomy via laparotomy. But in 21 cases, the procedure needed a laparotomy, and in 10 cases complications occurred, requiring laparotomy in 6 cases. Our results suggest: a) LC is an improvement in the treatment of uncomplicated gallstones; b) a trained surgeon and extreme caution are required in complicated cholelithiasis; c) classical cholecystectomy is still useful in many circumstances.

Adolescent↗
PubMed1992

[Cortical modulations of the fine temporal structures of impulse trains in the dorsal lateral geniculate body in cats].

In response to a visual stimulation, "replicated triplets" of impulses may appear in many spike trains recorded from the cat dorsal lateral geniculate nucleus (dLGN). The number and the temporal structure of these triplets depend upon the general organization of the geniculate impulse trains. In this study, we show that a pharmacological blockade of the corticothalamic activity, obtained through microinjection of GABA into area 17, affects the replicated triplet production and leads to an increase in the dispersal of their structure. These results suggest that the corticothalamic pathway closely influences the fine temporal organization of the geniculate messages.

Animals↗
PubMed1991

Temporal limits of the susceptibility of depth perception to proprioceptive deafferentations of extraocular muscles.

In a previous study, extraocular muscle proprioception (E.O.M.P.) was shown to play an important role in the postnatal development of depth perception: following unilateral or bilateral sections of the ophthalmic branch of the trigeminal nerve (V1th nerve) performed at 6-8 weeks of age, the binocular thresholds were 2 to 3 times higher than in control animals. Since the V1-sections produced no deficits when performed in adults, the temporal limits of a period of susceptibility remained to be determined. In order to assess the lower and upper limits of the period during which these perceptual deficits could be induced, unilateral or bilateral V1-sections were performed in kittens at different ages. Depth perception thresholds were measured by using the jumping stand technique. Sections of the V1 nerve only produced significant impairments of the binocular depth thresholds when performed after 3 weeks of age. They could be observed when unilateral sections were performed at up to 13 weeks of age and with bilateral sections at up to 10 weeks of age. These functional impairments appeared to remain permanently through adult life.

Animals↗
PubMed1991

[Clinical aspects of acute lesions of the brain stem of inflammatory origin].

The diagnostic considerations of an inflammatory brainstem disease and its symptoms are shown in 22 cases. The diagnosis based on a topodiagnostic decision and the demonstration of an inflammatory genesis. The topodiagnosis has to take into consideration that a symptom can be caused by both a central lesion as well as a peripheral nerve lesion. Electrophysiological methods (EEG, Nerve conduction velocity, reflex studies and evoked potentials) were of only minor use in these decisions. The somatosensory evoked potentials demonstrated 5 central lesions and were far more useful than the other methods. The CCT demonstrated a brainstem lesion in one case. In fifty percent of the cases, symptoms caused by both peripheral and central nerve lesions were demonstrated. Thus, there is no clear border between a brainstem encephalitis and a peripheral neuropathy (Fisher-Syndrome or Guillain-Barré-Syndrome). The inflammatory genesis was proven by CSF in 12 cases. An inflammatory disease was supported in the other cases through the exclusion of another genesis by means of CCT, NMR, Doppler sonography, angiography and an observation of the course of the illness.

Adolescent↗
PubMed1990

Conformational study of the chromosomal protein MC1 from the archaebacterium Methanosarcina barkeri.

Methanogen chromosomal protein MC1 is a polypeptide of 93 amino acid residues (Mr 10,757) which represents the major protein associated with the DNA of the archaebacterium Methanosarcina barkeri and can protect DNA against thermal denaturation. The conformation of protein MC1 has been investigated by means of predictive methods, infrared spectroscopy, circular dichroism and tryptophan fluorescence studies. Protein MC1 has a low amount of alpha-helix but contains antiparallel beta-sheet strands. The larger hydrophobic cluster which contains tryptophan at position 61 appears buried in the protein. Addition of salts induces the unfolding of the protein and makes the tryptophan indole ring more rigid. With respect to its primary structure and its conformation, protein MC1 appears radically different from the chromosomal DNA-binding protein II (also called HU-type protein) in eubacteria.

Amino Acid Sequence↗
PubMed1990

Temporal correlations in modulated evoked responses in the visual cortical cells of the cat.

We analysed evoked responses recorded from 97 cells in the visual cortex of 4 adult cats and 8 kittens, stimulated by a drifting sinusoidal grating. A Fourier analysis of the responses allowed us to select 30 cells showing a clear modulating response (relative modulation index greater than 1). The 162 records from these selected cells were scanned to detect precise temporal correlations in the form of replicating triplets and associated "ghost" doublets. Temporal correlations of this nature were observed in these cells. They are about 10 times more abundant in adult cats than in kittens, and mostly observed in infragranular cortical layer cells. The possible role of these precise temporal patterns in information processing in the brain is examined, as well as the relation between this type of temporal correlation with coherent oscillations and principal components waveforms.

Animals↗
PubMed1990

[Leukocyte differential of the Coulter VCS. Evaluation and modalities of use in comparison with the Coulter STKR and manual count].

The Coulter VCS is a flow cytometer which performs, from a 100 microliter blood sample, a full five-part differential by assessing the volume (V), high frequency conductivity (C) and laser light scatter (S) on each white cell counted. The authors evaluated the Coulter VCS and compared its results with those of the Coulter STKR (three-part differential) and of the manual count. Reproducibility (ten replicate analyses on six different normal samples) was studied by the three methods and showed coefficients of variation closed to the manufacturer's specifications except for monocytes. The correlation coefficients obtained from 345 normal samples were the following: VCS/manual count: 0.97 for neutrophils, 0.70 for eosinophils, 0.97 for lymphocytes and 0.57 for monocytes; VCS/STKR: 0.99 for granulocytes, 0.99 for lymphocytes and 0.70 for monocytes. Comparisons of means displayed statistical differences for some cell categories but without clinical consequences. The flag analysis of 313 abnormal samples showed a false positive rate of 3.1 p. cent for the VCS and 1.8 p. cent for the STKR, the false negative rate was 2.1 p. cent for the VCS and 3.6 p. cent for the STKR. Starting from total blood count parameters, the authors propose guidelines for appropriate use of the different leucocyte differential methods.

Algorithms↗
PubMed1989

Lesion of the PGO pathways in the kitten. II. Impairment of physiological and morphological maturation of the lateral geniculate nucleus.

Suppression of the geniculate ponto-geniculo-occipital (PGO) waves by bilateral lesions of PGO pathways at the mesencephalic level in 15-day-old kittens has been shown to induce a significant reduction of the mean discharge frequency recorded in the lateral geniculate nucleus (LGN) during paradoxical sleep. The present paper reports that one month after the bilateral lesion (i.e., 6-7 weeks of age) important deficits in the maturation of the LGN were observed: (1) electrophysiologically, the latencies of the LGN cellular responses to stimulation of the optic chiasm were significantly longer than those of age-paired controls or of unilaterally lesioned animals, and the proportion of visual cells characterized as type X by stimulation of the visual field was smaller; and (2) morphologically, the volume of the LGN and the size of its neuronal somata were smaller than those in control. These data suggest that bilateral suppression of extraretinal PGO afferents to the LGN in the kitten induces a significant delay in the development of this nucleus.

Action Potentials↗
PubMed1989

An expert system applied to the diagnosis of anemia with special reference to myelodysplastic syndromes.

An expert system is described that includes interpretation of the results from a complete blood count as well as data from bone marrow aspiration. The system utilizes Bayes' rule. It has previously been tested on 180 cases of anemia including 20 benign and malignant hematologic disorders. On the data set, the system achieved 84% satisfactory diagnoses. In the present study, patients with myelodysplastic syndromes and with disorders of heme synthesis have been added to the test cases. For support, the expert system requires an IBM Personal Computer or equivalent. The program is available commercially (Coulter Electronics, Hialeah, FL).

Anemia↗
PubMed1989

Adult patients presenting with pancytopenia: a reappraisal of underlying pathology and diagnostic procedures in 213 cases.

We reviewed 213 consecutive adult pancytopenic patients to determine the frequency of underlying pathology, to analyze our diagnostic procedure, and to determine the value of peripheral blood data for diagnosis. Pancytopenia was defined as the association of hemoglobin level below 12 g/dl in males and 11.5 g/dl in females, leukopenia below 4 x 10(9)/L, and thrombocytopenia below 150 x 10(9)/L. The bone marrow aspirates were normo- or hypercellular in 140 cases (66%). Bone marrow biopsies, performed in 93 cases, documented the presence of myelofibrosis in 67 cases. Aplastic anemia was diagnosed in 10% of the cases. Malignant myeloid disorders (acute myeloid leukemias, myelodysplastic syndromes, acute myeloid disorders with myelofibrosis) represented 42% of the cases and various malignant lymphoid disorders 18%. Vitamin deficiencies accounted for 7.5% and nonhematological pathology 10% of the cases. The bone marrow aspirate was sufficient for the diagnosis in 55% of the cases, and the trephine biopsy was necessary in 30%. In the remaining cases, other complementary tests were necessary to achieve final diagnosis. A discriminant analysis, focused on the hemogram data, showed that parameters obtained by analysis of blood smears were helpful for the diagnosis, especially the presence or absence of blast cells and/or of abnormal lymphoid cells.

Adolescent↗
PubMed1988

The primary visual cortex in the mouse: receptive field properties and functional organization.

Receptive field (RF) characteristics of cells in primary visual cortex of the mouse (C57B16 strain) were studied by single unit recording. We have studied the functional organization of area 17 along both the radial and tangential dimensions of the cortex. Eighty seven percent of the visual neurons could be classified according to their responses to oriented stimuli and to moving stimuli. Cells which preferred a flashed or moving bar of a particular orientation and responded less well to bars of other orientations or to spots, were classified as orientation selective (simple RF 23%, complex RF 18%). The majority of them were, moreover, unidirectional (24%). All orientations were roughly equally represented. Cells with oriented RFs were recorded mostly in the upper part of cortical layers II-III, where they appeared to be clustered according to their preferred orientation. Neurons that responded equally well to spots and bars of all orientations (46%) were classified as "non-oriented"; among these neurons there were several subcategories. Cells which responded equally well to spots and bars but preferred stimuli moving along one or both directions of a particular axis were classified as non oriented asymmetric cells (unidirectional 14%, bidirectional 4%). They were recorded mainly in supra- and infra-granular layers. Cells unaffected by stimulus shape and orientation which responded equally well to all directions of movement were classified as symmetric units. They had receptive field classified as ON (11%), OFF (1%), ON/OFF (11%), or were unresponsive to stationary stimuli (5%). These cells were mostly found in layer IV, in which they constituted the majority of recorded cells. There was no apparent correlation between the functional type and size of RFs. However, the greatest proportion of small RFs was found in layer IV. In the binocular segment of the mouse striate cortex, the influence of the contralateral eye predominated. Ninety five percent of cells in this segment were driven through the contralateral eye. However, 70% of cells were binocularly activated, showing that considerable binocular integration occurred in this cortical segment. Ocular dominance varied less along the radial than along the tangential dimension of the cortex.

Animals↗
PubMed1988

[Temporal correlations and coding of information in the visual cortex of the cat].

We have observed repeated patterns in evoked spike trains recorded from the primary visual cortex of the cat. These patterns are called "triplets" and "ghost doublets". Triplets are groups of three pulses, that may or may not be adjacent to one other, the mutual intervals of which are replicated in one other group of three spikes with a precision higher than 0.15 ms. Ghost doublets are doublets of pulses whose interval replicates, with the above precision, one of the intervals of the repeated triplets and are also present in the record. In one of the 9 recorded cells, in which pulses were clearly emitted in bursts in phase with the drifting of the sinusoidal grating used as a stimulus, we could show that local temporal correlations in the form of replicating triplets and ghost doublets correspond very precisely to the temporal phase of the grating: the study of the distance between triplets, or between triplets and ghost doublets, gives a remarkably precise value of the time frequency of the grating.

Animals↗
PubMed1988

Decision-making system (DMS) applied to hematology. Diagnosis of 180 cases of anemia secondary to a variety of hematologic disorders.

We have developed a new decision-making system which includes interpretation of complete blood count (CBC). The system works using Bayes' rule. We tested the CBC program for the diagnosis of 180 cases of anemia covering 20 benign and malignant hematological disorders. The data entered were obtained from a Coulter S + IV/HD and the interpretation of blood smears. Clinical information was not used. In 64.5% of cases, the correct diagnosis was displayed in first rank and in 20%, in second or third rank, giving a total of 84% of quite satisfactory responses. There were only 5% incorrect responses, but the proposed complementary tests rectified the error. Computer-aided diagnosis can help pathologists, clinicians, students, and technicians to make rapid correct diagnoses and choose the appropriate tests to perform. These programs run on IBM PC or similar microcomputers and are available from Coulter Electronics, Hialeah, FL.

Anemia↗
PubMed1987

[An aid in decision-making in hematology: characteristics and performances of the program. 200 cases of anemia].

An aid to decision programme has been applied to 200 cases of anaemia. Evaluation by the bayesian method rested on clinical data (age, sex, race) and laboratory data (blood count and differential, erythrocyte morphology). An accurate diagnosis was made initially in 107 cases, and for the first 5 diseases in 173 cases. The programme proved more effective than two clinicians recently trained in haematology. Devised for micro-computers, it can be used in routine practice and for teaching purposes.

Anemia↗