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Biomedical subjects

M Imbert

Publications and source records attributed to M Imbert.

At least 91 records · Page 5Linked to original sources
PubMed1983

Platelet peroxidase deficiency in a case of myelodysplastic syndrome with myelofibrosis.

Morphological and functional abnormalities of the megakaryocytic series have been well described in myelodysplastic syndromes. Platelet peroxidase has always been demonstrated in abnormal megakaryocytes and early megakaryoblasts in such syndromes. We have studied a case of myelodysplastic syndrome with marked morphological abnormalities of megakaryocytes in which ultrastructural studies showed the coexistence of platelet peroxidase positive and platelet peroxidase negative megakaryocytes. This enzymatic deficiency was confirmed by the ultrastructural study of circulating platelets. This case appears to be the first report of a partial platelet peroxidase deficiency. It adds to the enzymatic abnormalities in myelodysplastic syndrome already described for the red cells and the granulocytic cells.

Aged↗
PubMed1983

Prevalence and distribution of ringed sideroblasts in primary myelodysplastic syndromes.

In order to determine the prevalence and percentage distribution of ringed sideroblasts in primary myelodysplastic syndromes, the results of Prussian blue staining were analysed in 133 cases. Ringed sideroblasts ranging from 1 to 86% of cells were found in 76 (57%) cases. The cases of primary myelodysplastic syndrome corresponding to the group entitled "acquired idiopathic sideroblastic anaemia" had between 21 and 86% ringed sideroblasts; these were also found in 40% (26/65) cases corresponding to refractory anaemia with excess of blasts. Seven of the 22 cases having morphological features of refractory anaemia with excess of blasts in transformation had ringed sideroblasts. It would appear that cases of acquired idiopathic sideroblastic anaemia have at least 20% ringed sideroblasts; they also seem to occur frequently in refractory anaemia with excess of blasts.

Anemia, Aplastic↗
PubMed1982

[Noradrenaline and plasticity of the visual cortex of the kitten: a reexamination].

We have undertaken a study of the role of the noradrenergic system in the functional modifications, observed in the primary visual cortex of the Kitten, following monocular deprivation. The lids of one eye were sutured in 5 week old Kittens for a period of 1 or 2 weeks. Noradrenergic depletion was obtained by 6-OHDA injection, either intraventricular or localized in the coeruleus complex. Our results indicate that disappearance of noradrenaline in area 17 does not prevent the loss of binocularity of cortical cells, but appears to limit ocular dominance shifts at a stage equivalent to that observed in the intact Kitten after 6 days of monocular deprivation.

Animals↗
PubMed1982

Plasticity in the kitten's visual cortex: effects of the suppression of visual experience upon the orientational properties of visual cortical cells.

The orientation selectivity of visual cortical cells was tested in two groups of kittens. In one group the animals were reared normally for the first 4-6 weeks of life then kept in darkness. Those in the other group were dark-reared for the first 6 weeks then exposed to light for 6 h and returned to the dark. The properties of the receptive fields of visual cortical cells were examined in these kittens after periods of dark-rearing ranging from 3 days to 12 weeks. In both groups, the proportion of orientation selective cells was found to decrease with time spent in the dark. The critical period for orientation appeared to end at 10-12 weeks of age. Two populations of visual cells were distinguished functionally by their different behaviour during prolonged dark-rearing. Most of the cells which retained their orientation specificity longest during dark-rearing were tuned to horizontal or vertical orientations and more of them were monocular than in normal kittens. These functional characteristics resemble those exhibited by neurons of very young kittens. Changes in specificity observed during loss of selectivity are compared to those observed during early development. We suggest that the extent to which the orientation selectivity of a cell is plastic depends very largely upon the time, during the course of development, at which its selectivity was acquired.

Animals↗
PubMed1981

Effect of neonatal unilateral enucleation on the development of orientation selectivity in the primary visual cortex of normally and dark-reared kittens.

The developmental properties of 573 neurones have been investigated in the primary visual cortex of eight binocularly intact and twelve unilaterally enucleated kittens. It is shown that removal of one eye at birth alters the development of orientation selectivity observed in the presence or absence of visual experience. In 6-week-old deprived kittens, there remain significantly more orientation selective cells in enucleated than in binocularly deprived kittens. These deprivation-resistant cells respond preferentially to horizontal or vertical orientations and are recorded mainly in the cortex contralateral to the remaining eye. In six-week-old kittens with visual experience, the process of tuning maturation appears to be unaffected by unilateral enucleation at birth. However, a larger over-representation of horizontal and vertical orientation preferences is observed in uniocular kittens than in binocularly intact kittens, suggesting that the development of oblique orientation preference depends upon the presence of binocular afferents in the visual pathway.

Animals↗
PubMed1981

Distribution of 250 cases of acute myeloid leukaemia (AML) according to the FAB classification and response to therapy.

250 consecutive cases of AML in adults were diagnosed over a 6 year period in the same institution. Pretreatment blood and bone marrow smears and also cytochemical markers were taken into account in the study. All cases were reviewed by three different observers and classified according to the FAB criteria. The final diagnosis resulted from agreement of at least two observers. Some discrepancies occurred in the classification and are discussed. The prognostic implication of AML subclassification was assessed as the percentage of complete remission in 100 cases.

Adolescent↗
PubMed1981

Acute myelodysplasia with myelofibrosis: a report of eight cases.

Eight patients with acute myelodysplasia and myelofibrosis are described. Four cases were secondary to long-term therapy with cytotoxic agents and four were idiopathic. All cases presented with an abrupt onset of the illness, absence of organomegaly and severe pancytopenia. Bone marrow aspirate yielded adequate material in four cases and showed myelodysplasic features. Study of histological sections indicated that the bone marrow was cellular in every case, including numerous dystrophic megakaryocytes, erythroblasts, immature cells of the granulocytic series and blast cells which were difficult to identify. The reticulin network was always increased. In each case the disease was rapidly fatal. No improvement was noted with chemotherapy. In three cases an overt leukaemia developed with marked pleomorphism of blast cells. The nosology of this syndrome is discussed.

Adult↗
PubMed1980

The ipsilateral optic pathway to the dorsal lateral geniculate nucleus and superior colliculus in mice with prenatal or postnatal loss of one eye.

The projections, and more particularly the ipsilateral projections, from the retina to the dorsal lateral geniculate nucleus (dlGn) and the superior colliculus have been investigated in adult mice of the C57BL/6J strain after rearing in one of four different conditions: 1) after normal visual experience; 2) after unilateral enucleation at birth; 3) in mice with congenital unilateral anophthalmia (in which only one eye develops) 4) in mice with congenital unilateral microphthalmia (in which one eye is of reduced size while the other is normal). In neonatally enucleated and congenitally monocular mice there is an aberrant uncrossed pathway to regions of the dlGn and the superior colliculus which do not normally receive such a projection. This projection is limited in its distribution; in both the neonatally enucleated and the congenitally monocular animals the uncrossed projection does not reach the lateral and dorsal parts of the dlGn and it only innervates the rostral half of the superior colliculus. The density of the uncrossed pathway in these animals is highest in those regions in which the normal uncrossed pathway terminates. In microphthalmic mice the expansion of the uncrossed pathway is less marked than in monocular mice. In the superior colliculus the aberrant uncrossed projections innervate the stratum griseum superficiale where they are often found distributed in small patches. An intertectal crossing of retinal fibers is described from the contralateral superior colliculus to the deprived ipsilateral superior colliculus.

Animals↗
PubMed1980

Myelodysplasia and leukaemia related to chemotherapy and/or radiotherapy--a haematological study of 13 cases. Value of macrocytosis as an early sign of bone marrow injury.

Clinical and haematological features of 13 patients with secondary myelodysplastic syndromes (MDS) were studied, MDS developed subsequent to chemotherapy and/or radiotherapy for various haematological or non-haematological diseases. In six cases, the first sign was a persistently increased mean cell volume (MCV) and a macrocytosis preceding from 6 to 18 months the appearance of severe anaemia or acute leukaemia. In five cases, the initial finding was a macrocytic anaemia. Dysmyelopoiesis was a constant and prominent feature of the bone marrow smears at some time during the course of the disease. Two cases without macrocytosis at any time directly developed overt acute leukaemia.

Adult↗
PubMed1979

[Malignant myelofibrosis. One case (author's transl)].

In a 75-year-old man, the rapid development of a pancytopenia as a result to total marrow failure, in the absence of tumour or extramedullary myelopoiesis, but with a histological appearance of the marrow identical to that seen in agnogenic myeloid metaplasia led to a diagnosis of malignant myelofibrosis. The patient died 7 months after the apparent onset of the disease. The 48 other published cases are discussed. Only 17 are considered to be true cases of malignant myelofibrosis.

Acute Disease↗
PubMed1979

Thalamic afferents to the visual cortex in congenitally anophthalmic mice.

Retrograde cell labelling with horseradish peroxidase (HRP) has been used to study the thalamic afferents to the primary visual cortex (area 17) in mutant H1-ZRDCT-An ('eyeless') mice, in which the eyes are missing throughout development. Injections of HRP that were localised to a subregion of area 17, resulted in the labelling of a group of neurons in the ipsilateral dorsal lateral geniculate nucleus, showing the existence of a point-to-point connectivity. Many labelled cells were also found in other posterior thalamic nuclei especially in the lateral posterior nucleus which in normal animals contain very few or no labelled cells.

Animals↗
PubMed1979

Pseudo-Chediak-Higashi anomaly in a case of acute myeloid leukemia: electron microscopic studies.

The formation and fine structure of giant granules in neutrophil promyelocytes of a patient with a variant of acute myelogenous leukemia were investigated by electron microscopy. The patient presented with large lymph nodes and disseminated intravascular coagulation (DIC). By light microscopy, numerous giant granules, resembling those of Chediak-Higashi syndrome (CHS), were present, but Auer bodies could not be found. By electron microscopy, these giant granules were seen to be formed by fusion of azurophilic granules, as in CHS; however, they were different from the large granules of CHS, since they contained numerous microcrystalline structures like those of Auer bodies. However, the crystalline cores of these granules exhibited a periodicity different from that of Auer bodies of acute promyelocytic leukemia. This clinical and hematologic syndrome (giant granules, enlarged lymph nodes, and DIC may represent a variant of acute promyelocytic leukemia.

Adult↗