[Polynucleosis. Diagnostic orientation].
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Bacterial Infections↗
Biomedical subjects
M Imbert
Publications and source records attributed to M Imbert.
[Cytology of acute leukemia].
Cytological analysis of peripheral blood and bone marrow films is a quick and simple method for diagnosis of acute leukemia. In association with cytochemistry techniques it allows the rapid identification and subsequent classification of most types of acute myeloid leukemias. Although morphological analysis can suggest the diagnosis of an acute lymphoblastic leukemia, it is necessary to have the corroborating evidence of immunological markers for confirmation. In addition, ultrastructural studies contribute to the identification of rare forms of acute myeloid leukemias (minimally differentiated, megakaryoblastic). Cytological studies have also proven useful for the follow-up activities of confirming complete remission and detecting relapses.
Acute Disease↗
Neural processing of stereopsis as a function of viewing distance in primate visual cortical area V1.
1. The influence of viewing distance on disparity selectivity was investigated in area V1 of behaving monkeys. While the animals performed a fixation task, cortical cells were recorded extracellularly in the foveal representation of the visual field. Disparity selectivity was assessed by using static random dot stereograms (RDSs) through red/green filters flashed over the central fixation target. To determine the influence of the viewing distance, a color video monitor was positioned at fixed distances of 20, 40, or 80 cm. The same RDSs with the same angular size of dots were used at the three distances. 2. Disparity sensitivity was tested on 139 cells, of which 78 were analyzed at two or more distances and the rest (61) at a single distance. When disparity selectivity was analyzed at a given distance, about half the cells were found to be selective at 40 or 80 cm, but only a third at 20 cm. Near cells were > or = 1.5 times more common than far cells at all three distances. The latency distribution of the responses of disparity-selective (DS) cells was similar at all three distances, with a mean distribution centered around 60 ms. 3. Changing the viewing distance drastically affected the neural activity of the V1 neurons. The visual responsiveness of 60 of 78 cells (77%) was significantly changed. Disparity selectivity could be present at a given distance and absent at other(s), with often a loss of visual response. This emergence of disparity coding was the strongest effect (28 of 78 or 36%) and occurred more frequently from short to long distances. Among the cells that remained disparity insensitive at all recorded distances (31 of 78 or 40%), about half also showed modulations of the amplitude of the visual response. For cells that remained DS at all recorded distances (13 of 78 or 17%), changing the viewing distance also affected the sharpness (or magnitude) of disparity coding in terms of level of visual responsiveness and those changes were often combined with variations in tuning width. In only two cells did the peak of selectivity type change. Finally, the activity of four DS cells was not affected at all by the viewing distance. 4. Another effect concerned the level of ongoing activity (OA), defined as being the neural activity in darkness preceding the flash of the visual stimulus while the monkey was fixating the small bright target. Changing the viewing distance resulted in significant changes in OA level for more than half of the cells (41 of 78 or 53%). The most common effect was an increase in OA level at the shorter distance. The modulations of both visual responsiveness and OA could occur simultaneously, although they often had opposite signs. Indeed, the two effects were statistically independent of each other, i.e., modulations of visual responses were not related to the level of excitability of the neurons. 5. Control experiments were performed that showed that the effects of changing the viewing distance were not due to the retinal patterns in that the modulations of visual responsiveness were independent of the dot density. Seventeen cells were also tested for a possible effect of vergence by the use of prisms. When there was an effect of distance, it could be closely or partially reproduced by using prisms. These controls, together with the effects observed on OA, strongly suggest that the modulations of neural activity of the V1 neurons by the viewing distance are extraretinal in origin, probably proprioceptive. 6. The modulation of visual responsiveness by the viewing distance in the primary visual cortex indicates that integration of information from both retinal and extraretinal sources can occur early in the visual processing pathway for cortical representation of three-dimensional space. A functional scheme of three-dimensional cortical circuitry is discussed that shows cortical areas where disparity selectivity and modulations of visual activity by the angle of gaze have been described so far.
Animals↗
Pharmacokinetics of hydroxocobalamin in smoke inhalation victims.
OBJECTIVE: Hydroxocobalamin has been proposed as a cyanide antidote. Little is known, however, about its pharmacokinetics in human cyanide poisoning. METHODS: We prospectively studied the pharmacokinetics of hydroxocobalamin in 11 smoke inhalation victims of whom all but one had objective evidence of cyanide exposure. Serum hydroxocobalamin levels were followed from just before drug administration to six days after a single 5 g dose of hydroxocobalamin. RESULTS: The results (mean +/- standard error) suggest a two compartment model. Distribution half-life is on the order of 1.86 +/- 0.34 h and the elimination half-life 26.2 +/- 2.7 h. The apparent volume of distribution is 0.45 +/- 0.03 L/kg. Renal and total body clearance are 0.31 +/- 0.06 and 0.83 +/- 0.07 L/h, respectively. CONCLUSION: The apparent volume of distribution suggests a predominantly extracellular partitioning of the antidote, even in the presence of cyanide, an important factor in terms of its antidotal effect. Hydroxocobalamin's elimination half-life in these cyanide-exposed patients far exceeds those found in previous studies of dogs and minimally-exposed humans. If confirmed, this half-life suggests that a single dose of hydroxocobalamin, sufficiently large enough to bind the cyanide present, should be adequate.
Adult↗
Relation of blood cyanide to plasma cyanocobalamin concentration after a fixed dose of hydroxocobalamin in cyanide poisoning.
Hydroxocobalamin combines with cyanide to form cyanocobalamin. We hypothesised that the amount of cyanocobalamin formed after a fixed dose of hydroxocobalamin given for cyanide poisoning would correlate with initial blood cyanide concentration. We determined blood cyanide concentration in 12 patients exposed to residential fires, and compared this with markers of the amount of cyanocobalamin formed after treatment with 5 g intravenous hydroxocobalamin. All relationships were highly correlated (r2 0.79-0.95), for the whole group, and there appeared to be an almost linear relationship for the 9 patients with initial cyanide concentration below 40 mumol/L. Above this concentration, no further cyanocobalamin was formed from a single 5 g dose of hydroxocobalamin. In one patient with initial blood cyanide concentration of 96 mumol/L, however, plasma cyanocobalamin concentration approximately doubled after a second 5 g dose of hydroxocobalamin. 5 g of hydroxocobalamin appears capable of binding all available cyanide ions for blood cyanide concentrations up to about 40 mumol/L. Beyond this, more hydroxocobalamin must be given for remaining cyanide ions to be bound. This information will allow clinicians to use rapidly measurable plasma cyanocobalamin concentrations to gauge severity of exposure and evaluate adequacy of treatment.
Adult↗
Variations of the egocentric reference among normal subjects and a patient with unilateral neglect.
Thirty normal subjects and a patient with a left unilateral neglect were submitted to a straight-ahead pointing task in the three following trunk orientations: head and trunk aligned at 0 degree, and trunk rotated 15 degrees to the left or to the right relative to the head. The position of the egocentric reference was found to be dependent upon the trunk orientation, lateralization of the motor response and starting position, and thus on motor direction. The results are discussed with regard to egocentric hypotheses of neglect, spatio-motor cueing and scanning direction.
Adult↗
A diagnostic workstation for neoplastic bone marrow diseases: evaluation on 526 cases.
The diagnostic accuracy of a workstation for neoplastic bone marrow pathology was evaluated on 526 cases from two institutions. The workstation consists of knowledge-based systems for peripheral blood analysis, flow cytometry immunophenotyping, and bone marrow morphology, linked together by a relational database. The "gold standard" diagnosis was established by complete agreement among three hematopathologists after independent review of the data from each case. The workstation's diagnosis agreed with the "gold standard" in 515 cases (97.9%). In six of the 11 diagnostic errors, the bone marrow module could not reach a final diagnosis. The five misclassifications would not have resulted in a change of therapy for the patient. The institutional diagnosis of record agreed with the gold standard in 462 cases (87.8%). The results indicate that the workstation is capable of high-quality, reproducible, multiparameter interpretive reporting.
Acute Disease↗
Exhaustive analysis of the P53 gene coding sequence by denaturing gradient gel electrophoresis: application to the detection of point mutations in acute leukemias.
We report the set-up of a denaturant gradient gel electrophoresis (DGGE) assay to screen for mutations in the whole coding sequence of the p53 gene. These DGGE experimental conditions were applied to the analysis of the p53 gene in acute leukemias. Forty adults with acute myelogenous leukemia (AML) and 21 with acute lymphoid leukemia (ALL) were investigated. Eleven of the AML patients were investigated at the time of the initial diagnosis and at relapse. In contrast with most reports based on amplified fragments analyzed by single-strand conformation electrophoresis and focusing on exons 5 to 8, we analyzed the whole coding sequence of the gene. Two of the 40 AML patients displayed a point mutation in exon 7; it was either an A to G substitution that converted Tyr-234 to Cys, or a G to A change that converted Arg-248 to Gln. The screening procedure led to the discovery of several intronic and exonic polymorphisms. These results confirm the low incidence of p53 mutations in acute leukemias and suggest a limited role of the p53 protein in leukemogenesis. The computerized modeling and electrophoresis parameters presented here provide a powerful tool for the exhaustive characterization of p53 mutants in all kinds of malignancies.
Acute Disease↗
An analysis of the factors implicated in fire deaths in children.
The aim of this study was to determine: 1) the factors implicated in fire deaths in children, 2) the relevance of blood carbon monoxide (CO) and hydrogen cyanide (CN) concentrations in child fire victims. 34 child fire victims (17 males: 17 females) were studied. Mean age was 4.5 years. In 12 cases medico-legal autopsies were performed, but no toxicological analyses were done (group A). In 14 cases autopsies were not performed, but blood CO and CN concentrations were measured in the victims (group B). In the remaining 8 cases both toxicological analyses and medicolegal autopsies were done (group C). In 29 cases out of 34, children had been left alone by their parents. In 20 cases out of 34, children had 80% burns of their body surface. In groups A and C autopsies enabled violence or other criminal cause of deaths to be excluded. All victims had smoke inhalation. The mean blood CN concentration in the 22 fire victims (groups B and C) was 70.67 +/- 14.11 micromol/l (0-207). The mean blood CO concentration was 1.89 +/- 0.51 mmol/l (0.11-5.89). There was no significant correlation between CN and the CO blood concentrations. There was no significant correlation between the burn surface area and the blood concentration of either CN or CO. In 11 cases, one or both gases concentrations were in the potential toxic range (CN: 40-<100 micromol/l; CO: 1-<5.8 micromol/l) but below the lethal range. Therefore these deaths were considered to be due to the combined effect of gas toxicity. It is concluded that: 1) In case of fire death, a medico-legal autopsy should be performed to confirm that victims suffered smoke inhalation and to exclude violence or other criminal cause of deaths; 2) Blood CN and CO measurements identify the exact contribution of each to the death; 3) Immediate blood sampling at the scene of death should be done because CN may disappear rapidly from body tissue after death.
Journal Article↗
An expert system for the interpretation of flow cytometric immunophenotyping data.
The development of high-grade non-Hodgkin's lymphomas in HIV-positive patients and patients with acquired immune deficiency syndrome (AIDS) is a well known phenomenon. The proper classification of these neoplasms often requires a multiparameter approach, including the interpretation of a large panel of immunologic markers analyzed by flow cytometry. The availability of individuals with the required expertise to properly interpret these marker studies is limited. For this reason, we have designed an expert system to automate the analysis of immunophenotyping panels in both HIV-related and non-HIV-related hematopoietic neoplasms. The expert system, which we call "Professor Fidelio", runs on IBM-compatible computers under Windows 3.0. The system is designed to accept any number of markers studied from a repertoire of 35 markers. Professor Fidelio functions on the basis of heuristic classification of defined diagnostic patterns. Nine specific patterns (Stem Cell, Myeloid and/or Monocytic, Erythroid, Megakaryocytic, Immature B-cell, Immature T-cell, Mature B-cell, Mature T-cell, and Plasma cell) and one "non-specific" pattern have been agreed upon. Fidelio's knowledge base contains the definitions of each of these patterns and the heuristics for excluding patterns when an incomplete panel of markers is performed. The inference engine interprets the findings (including the age of the patient) and reports the patterns which are matched, the differential diagnosis, the suggested diagnosis from the list of differentials if the marker studies are specific, and recommendations for additional tests which may be valuable in establishing the diagnosis.(ABSTRACT TRUNCATED AT 250 WORDS)
Acquired Immunodeficiency Syndrome↗
Egocentric reference and asymmetric perception of space.
Normal dextrals performed tactilo-kinesthetic bisection tasks in a median position, at three directions of gaze: 30 degrees to the left, 30 degrees to the right, 0 degree. Instead of pseudoneglect phenomenon, a deviation of the subjective middle to the side opposite to the direction of gaze and hand use was found, whichever hand was used. The results are interpreted in terms of displacement of the position of the egocentric reference and are discussed with respect to activation theory. It is argued that pseudoneglect is part of a more general asymmetric perception of space phenomenon which depends on the position of the egocentric reference.
Adult↗
Influence of reading habits on line bisection.
The effect of scanning direction on perception of space is studied with a visuo-motor bisection task, among 120 normal dextrals with opposite reading habits (60 French subjects, 60 Israeli subjects). Bisection is found to depend upon subject's reading habits. Israeli bisected the line to the right of the objective centre, while French subjects placed their subjective middle to the left of the objective one. Results are discussed with respect to hemispheric activation theories, directional hypotheses and the neglect syndrome.
Adolescent↗
Long-term dysfunctions of neural stereoscopic mechanisms after unilateral extraocular muscle proprioceptive deafferentation.
1. Neural correlates of the permanent deficits in depth perception that occur when extraocular muscle proprioceptive (EMP) afferents are interrupted unilaterally in kittens were investigated by performing extracellular recordings in the primary visual cortex (area 17) in adulthood. Unilateral section of the ophthalmic branch of the trigeminal nerve (V1 nerve) were performed in 11 cats when they were between 5 and 12 weeks of age (uni-V1 group). Electrophysiological results were compared with those obtained in 17 normal adult cats (control group). 2. Binocular interactions were assessed by testing the sensitivity of cortical neurons to dichoptic presentations of moving sine-wave gratings whose interocular positional phase relationship was randomly varied. The amplitude modulation between the minimum and the maximum binocular responses defined the dynamic range. The degree of binocular suppression or facilitation was assessed by comparing these binocular response limits with the optimal monocular responses evoked through either eye at the best spatial frequency. The variability of both monocular and binocular responses was estimated by using the variation coefficient. 3. In uni-V1 cats, both the dynamic range and the degree of binocular suppression were significantly less pronounced than in controls, whereas binocular facilitation was not affected. The variability of the binocular responses was significantly increased, unlike monocular responses, whose variability was similar to control values. 4. From Fourier analysis of the poststimulus time histograms, two clear-cut categories of cells emerged that were differentially affected in the uni-V1 group. The "modulated" cells showed significantly less binocular suppression than in controls, and the "unmodulated" cells had binocular responses that were significantly more variable than in controls. Results from "simple" cells were similar to those of modulated cells, and results from "complex" cells were similar to those of unmodulated cells. However, in the unmodulated population, which was composed of both simple and complex cells, it was shown that the increase of variability was due to that of complex cells. 5. A nonparametric statistical test was applied on the interocular phase shift tuning curves to determine the minimum stimulus change necessary to elicit a significant change in the neural response. Two categories of cells were determined: the "discriminative" cells (80% in controls but 45% in uni-V1 cats) combined pronounced binocular suppression and dynamic range with relatively low variability. The reverse was true in the case of "nondiscriminative" cells (20% in controls and 55% in uni-V1 cats). 6. In uni-V1 cats, about half of the cells were monocularly activated.(ABSTRACT TRUNCATED AT 400 WORDS)
Afferent Pathways↗
Adult T-cell leukemia-lymphoma: a clinico-pathologic study of twenty-six patients from Martinique.
Twenty-six cases of adult T-cell leukemia/lymphoma (ATLL) were identified between 1983 and 1991 in Martinique (French West Indies). There were 14 men and 12 women, all of mixed racial descent and born in Martinique. Their ages ranged from 23 to 95 years. The main clinical and laboratory features at initial presentation were peripheral lymphadenopathy (22 cases), hepatomegaly (11 cases), splenomegaly (10 cases), cutaneous lesions (12 cases), hypercalcemia (16 cases), refractory infection by Strongyloides stercoralis (12 cases), and pre-existing autoimmune disorders (4 cases). All patients had absolute lymphocytosis with circulating pleomorphic abnormal lymphocytes. The prognosis was poor, with most patients (20 cases) surviving for less than 6 months. Although the overall clinicopathologic features of ATLL in this series are similar to those described in previous reports, we observed three additional points of interest: a high association with Strongyloides infection, an increased incidence of tropical spastic paresis/HTLV-1 associated myelopathy (TSP/HAM) among the relatives of the patients (5 cases), and the presence of prior collagen vascular diseases.
Adult↗
[Polynucleosis. Diagnostic orientation].
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Humans↗
[Lymphocytosis. Diagnostic orientation].
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Diagnosis, Differential↗
Modulation of neural stereoscopic processing in primate area V1 by the viewing distance.
Accurate binocular depth perception requires information about both stereopsis (relative depth) and distance (absolute depth). It is unclear how these two types of information are integrated in the visual system. In alert, behaving monkeys the responsiveness of a large majority of neurons in the primary visual cortex (area V1) was modulated by the viewing distance. This phenomenon affected particularly disparity-related activity and background activity and was not dependent on the pattern of retinal stimulation. Therefore, extraretinal factors, probably related to ocular vergence or accommodation, or both, can affect processing early in the visual pathway. Such modulations could be useful for (i) judging true distance and (ii) scaling retinal disparity to give information about three-dimensional shape.
Animals↗
Effect of dark rearing on the volume of visual cortex (areas 17 and 18) and number of visual cortical cells in young kittens.
The surface area, total volume, and total number of neurons of areas 17 and 18 in one hemisphere of dark-reared (DR), dark-reared and light-exposed (DRL), and normally reared (NR) kittens were studied at the age of 6 weeks. The thickness of the visual cortex was lower by 13% and 11% (area 17) and by 17% and 16% (area 18) in DR and DRL groups, respectively, when compared with similar cortical areas in NR kittens. The surface area values of area 17 were nearly the same in DR and DRL kittens, both being, however, 37% smaller than in NR animals. The surface area of area 18 was significantly smaller than that of area 17 in each group, and was also lower in DR (by 27%) and DRL (by 21%) groups when compared with the NR group. As a consequence of dark rearing, the numerical density of cortical neurons in area 17 amounted to about double of the value observed in normally reared kittens and was also significantly higher in area 18. The numerical density of nerve cells of DRL kittens fell between the DR and NR groups. The total cortical volume of area 17 was similar in DR and DRL groups but it was by 46% (DR) and by 44% (DRL) smaller than in NR kittens. In each experimental group, the total volume of area 18 was significantly smaller than that of area 17. The cortical volume of area 18 was also smaller than in the NR group by 39% and 34% in DR and DRL groups, respectively. In DR and NR kittens, the total numbers of neurons in areas 17 (DR = 26.4 million, NR = 25.7 million) and 18 (DR = 8.5 million, NR = 9.0 million) were essentially similar. In the DRL groups a significantly smaller number of cortical neurons was found both in area 17 (21.5 million) and in area 18 (6.8 million). It is concluded that, in spite of considerable differences in the cortical thickness, surface area, numerical density, and total cortical volume, the absolute numbers of neurons in area 17 and 18 of visually deprived (DR) and NR kittens do not differ at 6 weeks of age. The main deficit in cortical organization following dark rearing, therefore, appears to be confined mainly to the neuropil, as a result of an underdevelopment of neuronal processes and of depressed synaptic organization.(ABSTRACT TRUNCATED AT 400 WORDS)
Animals↗