Search PubMed⌕ Search

Biomedical subjects

P Laharrague

Publications and source records attributed to P Laharrague.

At least 19 recordsLinked to original sources
PubMed2005

Plasticity of adipose tissue: a promising therapeutic avenue in the treatment of cardiovascular and blood diseases?

The adipose tissue represents a large amount of adult tissues. For long time, it was considered as a poorly active overgrown and undesirable tissue even if its usefulness was demonstrated in reconstructive surgery. It was studied for its main involvement in energy metabolism and disorders as diabetes and obesity. More recently, its endocrine functions emerged and appeared to play a key role in many physiological situations such as inflammation and immunity. The presence of preadipocytes throughout life was demonstrated using primary culture technology from cells derived from adipose tissue. These cells can display a macrophagic or endothelial potential according to their environment and could be now considered as vascular progenitors. Differentiation of various adipose derived cell subsets towards functional cardiomyocytes, osteoblasts, haematopoietic and neural cells was also obtained in vitro. Altogether, these data emphasise the need to consider with a new look preadipocyte status and adipose tissue biology. These spectacular data, together with the fact that adipose tissue is easy to obtain lead to numerous and promising perspectives in regenerative medicine. They highlight the concept that progenitor cells from adipose tissue constitute an alternative for cells-based strategies designed for the treatment of cardiovascular diseases.

Adipose Tissue↗
PubMed2004

[Adipose tissue, plastic and reconstructive surgery: come back to sources].

The adipose tissue represents a large amount of adult tissue. For long time, it was considered as a filling tissue and used in plastic and reconstructive surgery. It was always studied for its main involvement in energy metabolism and energy disorders as diabetes and obesity. More recently, its endocrine functions emerged and thus play a key role in many physiological functions as inflammation and immunity. The presence of preadipocytes throughout life was demonstrated using primary culture technology from cells derived from adipose tissue. In recent papers, cells derived from adipose tissue were used for haematopoiesis, vascularisation or skeletal muscle recovery. Differentiation into functional cardiomyocytes, osteoblasts and neural cells was obtained in vitro. These spectacular data, the fact that adipose tissue is easy to sample and the possibility to create cell or tissue banks open numerous and promising perspectives in regenerative medicine.

Adipocytes↗
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↗
PubMed1999

A role for preadipocytes as macrophage-like cells.

Several lines of evidence have supported a link betweeen adipose tissue and immunocompetent cells. This link is illustrated in obesity, where excess adiposity and impaired immune function have been described in both humans and genetically obese rodents. In addition, numerous factors involved in inflammatory response are secreted by both preadipocytes and macrophages. Here we show that proliferating preadipocytes in cell lines and primary cultures, develop phagocytic activity toward microorganisms. This is demonstrated by phagocytosis assays and confocal microscopy. This function disappears when preadipocytes stop proliferating and differentiate into adipocytes. After phagocytosis, preadipocytes show microbicide activity via an oxygen-dependent mechanism. In addition, preadipocytes as well as adipocytes are stained with MOMA-2, a marker of monocyte-macrophage lineage, but are negative for specific mature macrophage markers (F4/80 and Mac-1). These results suggest that preadipocytes could function as macrophage-like cells and raise the possibility of a potential direct involvement of adipose tissue in inflammatory processes.

Adipocytes↗
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

Establishment and characterization of a human T-lymphocyte cell line immortalized by SV40 and with abnormal expression of TCR/CD3.

Human lymphocytes derived from the peripheral blood of a healthy woman were transfected with a plasmid carrying the simian virus 40 (SV40) large T antigen. The successfully transformed cells contained SV40 large T DNA and were negative for Epstein-Barr virus (EBV) and human T-cell leukaemia virus (HTLV)-1 genomes. The immortalized cell line was assigned to the T-lymphocyte lineage on the basis of morphological, immunological and cytochemical criteria. While the cells expressed CD1a and CD4 at the cell surface, the CD3 complex was solely intracytoplasmic. Immunoprecipitation studies indicated that these cells lacked T-cell receptor (TCR) alpha-chains but not beta-chains. They were negative for activation markers such as CD25, CD69 and major histocompatibility (MHC) class II molecules. In addition, the transformed cells exhibited a complete growth independency towards interleukin-2 (IL-2). However, after phorbol ester stimulation, CD25 and CD69 markers were expressed and IL-2 was secreted. This new human immortalized T-lymphocytic cell line, which is cell-surface TCR/CD3-negative, may be useful as an in vitro model for studying TCR/CD3 assembly, expression and signal transduction.

Antigens, Polyomavirus Transforming↗
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↗
PubMed1997

Kupffer cells are a dominant site of uncoupling protein 2 expression in rat liver.

The mechanisms underlying thermogenesis in liver are not well understood. They may involve proteins related to the mitochondrial uncoupling protein (UCP1) of brown adipocytes. In this paper, it is demonstrated that UCP1 is not expressed in any liver cell type of rat while UCP2, a recently cloned homologue of UCP1, is expressed at a very high level in Kupffer cells but not in hepatocytes. This high level of expression of UCP2 in Kupffer cells allowed cross immunoreactivity with antibodies directed against UCP1. This cross reactivity was confirmed by the detection of UCP2 with anti-UCP1 antibody, in western blotting analysis of transfected yeasts expressing rat UCP2. The high level expression of UCP2 in Kupffer cells suggests a particular function of UCP2 in macrophages.

Animals↗
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↗
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↗
PubMed1990

[Evaluation of an automatic analyzer of reticulocytes: the Sysmex R-1 000].

The microscopic enumeration of reticulocytes is a tedious assay with poor reproducibility. Its results provide only fragmentory information on the kinetics of erythropoiesis. Thus, attempts have been made for its automation. This study presents results of an evaluation of the first machine exclusively devoted to reticulocyte analysis. The Sysmex R-1 000 uses flow cytofluorometry with argon laser, after precipitation of nucleic acids by auramine-O. The whole study was performed according to ICSH recommendations. At least 2,500 erythrocytes were examined in the microscopic reference technique, after 1 p. cent brilliant cresyl-blue staining. Within and between-batch precision studies gave CV not exceeding 5.46 and 8.72 p. cent respectively for reticulocyte numbers. In dilution study it was shown that no measured result was over 4 p. cent of the expected value, in the range 4-400 x 10(9)/l. There was no significant carry-over in the range tested (35-510 x 10(9)/l). Accuracy testing proved that the significant difference observed when microscopic enumeration was performed in routine conditions disappeared when at least 5,000 erythrocytes were examined. Keeping the samples at 4 degrees C limited the decrease of the reticulocyte number to less than 10 p. cent after 24 hours. Analysis of some particular clinical situations demonstrated the risk of spurious results in case of massive Plasmodium infestation, and the usefulness of obtaining the percentage of newly emerged reticulocytes, i.e. the most fluorescent, for a better estimate of the kinetics of erythrocyte production. This evaluation testifies the quality of the Sysmex R-1 000, and underlines the potential benefit of such analyzers in the equipment of the modern hematology laboratory.

Erythrocyte Count↗