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Biomedical subjects

J X Corberand

Publications and source records attributed to J X Corberand.

At least 19 recordsLinked to original sources
PubMed2000

High concentration of leptin stimulates myeloid differentiation from human bone marrow CD34+ progenitors: potential involvement in leukocytosis of obese subjects.

OBJECTIVE AND DESIGN: As well as its involvement in control of adipose mass and body energy balance, several reports suggest a link between leptin and hemopoiesis. To test its putative role in human hemopoiesis, we developed a homologous system, ie recombinant human leptin treatment of purified CD34+ progenitors from adult human bone marrow. RESULTS: Leptin (50-100 ng/ml) significantly stimulated the appearance of granulocyte-macrophage colonies in the presence or absence of erythropoietin. The concentration of leptin required for this effect was rather high but within the range of plasma leptin levels observed in obesity. Two results further support the hypothesis that leptin may be involved in the leukocytosis associated with obesity: (i) leptin concentrations in bone marrow and plasma of subjects studied were highly correlated; (ii) leptin and leukocyte count were correlated only in obese subjects. Paracrine effects of locally released leptin from bone marrow adipocytes could also be involved in the regulation of hemopoiesis, a hypothesis supported by marrow immunocytochemistry revealing the close association of CD34+ cells with adipocytes and by previous demonstration that leptin is secreted at a high level by these cells. CONCLUSION: These results indicate that leptin acts on human multilineage CD34+ cells and that high plasma leptin levels associated with obesity could participate in the differentiation of granulocytes from hemopoietic progenitors.

Adult↗
PubMed2000

Regulation by cytokines of leptin expression in human bone marrow adipocytes.

Leptin is a hormone secreted by adipocytes. Besides controlling appetite and body weight, it has been suggested that leptin plays a role in inflammation and hemopoiesis. In this study we demonstrate that the pro-inflammatory/hemopoietic cytokines, IL-1beta, IL-6, TNF-alpha, and interferon-gamma, significantly inhibit gene expression and secretion of leptin by bone marrow adipocytes. These findings are in agreement with the data recently obtained from non-medullary adipose tissues. Within the bone marrow environment, leptin regulation by these pleiotropic cytokines could contribute to controlling the proliferation and differentiation of hemopoietic precursors as well as the maturation of stromal cells.

Adipocytes↗
PubMed2000

Inflammatory/haematopoietic cytokine production by human bone marrow adipocytes.

Adipocytes are now considered as secretory and endocrine cells. White and brown adipocytes synthesize and secrete a variety of cytokines, among a number of peptide and non-peptide products. Some of these cytokines, particularly IL-6 and TNF-alpha, appear multifunctional since they may be involved in the control of adipose mass, inflammatory response and haematopoiesis. Bone marrow adipocytes are another abundant type of adipocytes, but their precise role in humans is poorly understood. In the present study, we demonstrate that, in contrast to non-medullary adipocytes, human bone marrow adipocytes in primary culture secrete only trace amounts of IL-1 beta and TNF-alpha, but, they secrete significant and regulated levels of IL-6. These results reinforce the concept of functional heterogeneity of adipose tissues according to their anatomical localization, and indicate that bone marrow adipocytes may contribute to the complex network of cytokines involved in the control of haematopoiesis.

Adipocytes↗
PubMed1999

Evaluation of the Vega haematology analyser in a university hospital setting.

The performance of the ABX Vega haematology analyser was compared with that of the Sysmex NE-8000, with specific attention to flagging performance and ergonomics. Eight hundred routine samples underwent precision and interinstrument variability studies and 168 samples corresponding to various blood disorders were studied meanwhile. Results from the two instruments gave excellent correlation (r > 0.900) for most parameters except MCHC (r = 0.114), basophil and monocyte percentages (r = 0.617 and 0.552, respectively). The reproducibility, repeatability, linearity, carry-over and stability of the Vega were satisfactory; 'flagging' occurred in 31% of routine samples with sensitivity 88.8%, specificity 41.3% and positive predictive value 85.7%. Various flags appeared in 91% (42/46) of cases where blast cells were microscopically identified. In the four remaining cases, CBC anomalies would themselves have justified microscopic examination of a smear. On 'CBC only' mode reagent consumption was significantly reduced. In the laboratory the analyser was best appreciated for its user-friendliness.

Autoanalysis↗
PubMed1998

Atypical neutrophil alkaline phosphatase associated with impaired neutrophil functions.

We report the case of a healthy young man presenting with atypical neutrophil alkaline phosphatase (NAP) and reduced neutrophil chemotactic activity, but with no susceptibility to infection. NAP activity was low, kinetic parameters were modified and immunoreactive properties and subcellular distribution were abnormal. Neutrophil morphology was normal. A similar pattern was observed in the patient's healthy brother. The profile of the observed anomalies offers some similarity to that previously described in patients with chronic myelogenous leukaemia. However, in the present case, the NAP deficiency with impaired neutrophil function was present in two brothers with no haematological symptoms and is probably related to a non-acquired neutrophil abnormality. This observation of a primary NAP variant reinforces the hypothesis of a direct link between NAP activity and functional properties of neutrophils.

Adult↗
PubMed1998

High expression of leptin by human bone marrow adipocytes in primary culture.

Adipocytes participate in the microenvironment of the bone marrow (BM), but their exact role remains to be determined. It has recently been shown that leptin, a hormone secreted from extramedullary adipocytes, could be involved in hematopoiesis. Therefore we have developed a primary culture system of human BM adipocytes to characterize their differentiation and determine whether leptin is also secreted from these adipocytes. BM cells were cultured with fetal calf and horse sera. In the presence of dexamethasone, cells with vesicles containing lipids appeared within 15 days. They expressed glycerol phosphate dehydrogenase activity and a lipolytic activity in response to isoproterenol, but expressed neither the adrenergic beta3 receptor nor the mitochondrial uncoupling protein UCP1. The addition of insulin alone to the culture media did not promote adipocyte differentiation. Leptin was expressed and secreted at high levels during adipocyte differentiation. Acute exposure of differentiated adipocytes to insulin had little effect on leptin expression whereas forskolin strongly inhibited it. These results show that although human BM adipocytes differ from extramedullary adipose tissues in their sensitivity to different effectors, they are a secondary source of leptin production. They suggest that BM adipocytes could contribute to hematopoiesis via the secretion of leptin in the vicinity of hematopoietic stem cells.

Adipocytes↗
PubMed1996

Isolation of bone marrow plasma cells by negative selection with immunomagnetic beads.

In order to isolate bone marrow plasma cells from patients presenting with multiple myeloma or monoclonal gammopathy of undetermined significance, we developed a method for purifying these cells by negative selection using monoclonal antibodies and immunomagnetic beads. The results presented here were obtained from 75 procedures. Purity was extremely variable (2-100%) and was dependent on the percentage of plasma cells in the original bone marrow sample with a 10% cut-off, beyond which purity was over 96% in all cases. The mean yield was about 20%. The cells collected were viable and suitable for immunophenotyping, semi-quantitative studies of oncoproteins, and PCR.

Antibodies, Monoclonal↗
PubMed1996

Reticulocyte analysis using flow cytometry.

Automation of the reticulocyte count by means of flow cytometry has considerably improved the quality of this investigation. This article deals firstly with the reasons for the poor performance of the microscopic technique and with the physiological principles underlying identification and classification of reticulocytes using RNA labeling. It then outlines the automated methods currently on the market, which can be classified in three categories: a) "general-purpose" cytofluorometers, which in clinical laboratories usually deal with lymphocyte immunophenotyping; b) the only commercially available cytofluorometer dedicated to the reticulocyte count; this automat has the advantage of requiring no human intervention as it merely needs to be fed with samples; c) hematology analyzers with specific modules for automatic counting of reticulocytes previously incubated with a non-fluorescent dye. Of the various fluorescent markers available, thiazole orange, DEQTC iodide and auramine are most often used for this basic hematology test. The quality of the count, the availability of new reticulocyte indices (maturation index, percentage of young reticulocytes) and rapidity of the count give this test renewed value in the practical approach to the diagnosis of anemia, and also open new perspectives in the surveillance of aplastic anemia after chemotherapy or bone marrow grafting.

Anemia↗
PubMed1996

The performance of the knowledge-based system VALAB revisited: an evaluation after five years.

In 1988, inundated by the tedious work of validation of laboratory reports in a large hospital biochemistry laboratory, we designed VALAB, a knowledge-based system specially dedicated to this iterative function. Coping at first with a few biochemical tests, the program has been progressively expanded to forty-five common chemical tests. Simultaneously some new rules have been introduced to "weight" the conclusion in different circumstances and rules taking into consideration some clinical data have also been written. Moreover the program moved to other disciplines, pH and blood gases, haematology and coagulation. Accordingly the evaluation protocol has been modified, incorporating a new step, the consensus decision of the pathologists, operating within the initial protocol and based upon the various criteria of epidemiology. These major changes and improvements have led us to check and describe again the performance of this updated VALAB knowledge-based system.

Artificial Intelligence↗
PubMed1994

[Computer-assisted validation system applied to hematology: Valab-hemato].

Validation of laboratory reports is the ultimate step before transmission of results to the clinician. The biologist checks the intrinsic consistency of the data as well as their possible medical value that is liable to lead to other investigations. Such a policy, when performed on all the data, is time-consuming, boring and uncertain. This step may be simplified by the use of a computerized expert system. The computer assisted validation system presented here concerns routine haematology data (Valab-haemato). Like its predecessor devoted to clinical chemistry (Valab-Biochem) it is based on the performance of a powerful inference engine which generates a decision-making tree for each report according to the data. This adaptability gives the system a capacity very close to human reasoning. In its haematology version the system deals with many variables including sex, age, origin of the patient (hospital ward), and the haematological data (blood cell count, differential, reticulocyte count, various information drawn from microscope examination of the blood smear as well as any report concerning the blood sample, erythrocyte sedimentation rate). Previous data are also taken into account, as well as the normal ranges, the values beyond which no result can be automatically validated and the delta-check. Some information definitely prevents validation of the results, others can be validated if they have been previously approved. Whereas the method of reasoning is fixed, all items are changeable in order to adapt the system to the type of activity of the laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

Artificial Intelligence↗
PubMed1993

Plasma fibrinogen and physiological aging.

Results of prospective studies indicate that increased fibrinogen concentration is significantly associated with the risk of arteriosclerotic vessel disease. As the fibrinogen concentration is considered to rise with aging, determination of its physiological values with various methods in strictly healthy adult and aged individuals is a prerequisite to evaluating the relative contribution of fibrinogen to cardiovascular diseases. Fibrinogen concentration was determined in 209 healthy subjects, aged 19 to 96 years. Persons over the age of 60 were recruited according to the stringent criteria of the Senieur protocol established for human immunogerontological studies. Fibrinogen concentrations, obtained by heating precipitation and by thrombin clotting time with both electromagnetic water-bath and semiautomatic coagulometer, ranged from 1.55 to 3.70 g/L. A rise in plasma concentration was observed with aging. Independently of age, females exhibited higher concentrations than males. Significantly higher values were observed in subjects over 60 years of age, in both sexes, in comparison with the younger groups.

Adult↗
PubMed1992

Peripheral intramonocytic leishmanias in an AIDS patient.

Intramonocytic leishmanias were unexpectedly observed in blood smears of a Spanish AIDS patient. In immunodepressed patients from exposed countries, careful microscopic examination of blood smears should be requested by the clinician in cases of prolonged fever, and biologists must be informed that leishmanias may be fortuitously observed in the peripheral blood.

AIDS-Related Opportunistic Infections↗
PubMed1992

Evaluation of a new haematology analyser for whole blood count and full differential (NE-8000).

We evaluated the fully automated haematology analyser TOA Sysmex NE-8000 over a three-month period according to the ICSH protocol using as reference techniques a Coulter STKR counter and microscope examination for WBC differential and cell morphology. The NE-8000 employs aperture impedance to perform cell counts, with a sheath fluid to focus cells hydrodynamically prior to counting and sizing. WBC are differentiated into five populations. A combination of aperture impedance, radio frequency measurement and differential cell shrinkage is used, eosinophil and basophil percentages being established in two separate channels and subtracted from the total granulocyte count in order to give the value for neutrophils. Analysis of 1060 samples processed by the closed sampling automode demonstrated satisfactory counting performance. Among the WBC differentials obtained from 100 samples, neutrophil, eosinophil and lymphocyte results correlated well with those from microscopic examination of blood smears performed according to the NCCLS standard H20 T protocol. Differences observed in the percentages of basophils were of no biomedical significance. A comparative study for monocytes showed poor correlation for values below 5% and above 10%, best results being obtained in the intermediate range 5-10%. The NE-8000 also demonstrated good reliability for detection of abnormal cells.

Automation↗
PubMed1992

Bone marrow enrichment technique for detection and characterization of scarce abnormal cells.

A frequent problem encountered in analysis of bone marrow aspirates is the small number of suspect cells in the material. We present a method for concentration of the cells in bone marrow aspirates which yields smears suitable for immunocytochemical techniques. Bone marrow sampling is performed in two steps: a first aspirate is used to prepare conventional smears and a second aspirate is submitted to two-step centrifugation to separate and collect the nucleated cells without use of a separation medium. Sufficient material is obtained to prepare a large number of films, thus allowing immunocytochemical investigation with a wide panel of monoclonal antibodies. The proportions of the different cell types are similar to those observed in conventional smears and cell morphology is unaltered. This enrichment procedure improves the accuracy of routine cytological bone marrow examination, may be easily applied in laboratories performing bone marrow studies and in our hands has proved of value for the detection and characterization of both malignant blood diseases and bone marrow dissemination of carcinoma.

Bone Marrow↗