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Biomedical subjects

P Laharrague

Publications and source records attributed to P Laharrague.

At least 19 recordsLinked to original sources
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↗
PubMed1987

Blood cell parameters do not change during physiological human ageing.

Despite the considerable amount of data published during the last 30 years concerning the hematological status of the aged, practitioners are still confronted with the problem of 'normal' or 'physiological' values in these subjects. Indeed, significantly different values are presented in the literature as normal for the aged, apparently depending on the various types of populations studied. Criteria used to define the subjects as 'normal' could be the main factor responsible for this discrepancy. Based on this hypothesis, we determined the values of usual blood cell parameters in two groups of apparently healthy subjects of over 75 years of age. Subjects of group A (16 men and 13 women) were selected according to the stringent criteria of the Senieur protocol and subjects of group B (15 men and 20 women) were recruited using 'conventional' admission criteria. For both groups, sex-matched young controls aged 20-29 years were tested in parallel. No clinically significant alteration was observed in group A, whereas more pronounced differences were found in group B. Our results confirm the necessity for stringent selection criteria in biological investigations in gerontology. Moreover, they demonstrate that blood cell parameters are not altered in the aged, provided that the latter are really 'healthy'.

Aged↗
PubMed1985

A rapid isolation procedure of plasma membranes from human neutrophils using self-generating Percoll gradients. Importance of pH in avoiding contamination by intracellular membranes.

In this study we report an overall procedure for the isolation of both human polymorphonuclear neutrophils and their plasma membrane, by means of self-generating Percoll gradients. After efficient purification (40% yield), neutrophils were lysed by nitrogen cavitation and cellular structures quickly isolated in a one-step procedure. Plasma membrane recovery was monitored by [3H]concanavalin A and 5'-nucleotidase (EC 3.1.3.5) activity. We showed the latter activity is indeed present in human neutrophils. The procedure resulted in a good yield of plasma membrane, since 45% and 55% of total 5'-nucleotidase and [3H]concanavalin A activity, respectively, were recovered within two gradient fractions. Depending on the final pH of the Percoll gradient medium, endoplasmic reticulum markers contaminated either the plasma membrane or the granule fractions. At pH 9.05, NADH-ferricyanide reductase activity clearly separated from plasma membrane markers and displayed the same profile as CDPcholine:diacylglycerolcholine phosphotransferase (EC 2.7.8.2), a typical enzyme of endoplasmic reticulum. These results emphasize the need for strict monitoring of the pH of the gradient medium in subcellular fractionation of neutrophils.

5'-Nucleotidase↗
PubMed1985

[Effect of ethanol on human polynuclear neutrophils. In vitro and in vivo study].

Human polynuclear neutrophilic function was studied to determine the role of alcohol in the increased susceptibility to infection of chronic alcoholics: in vitro studies investigated the effects of different concentrations of ethanol; in vivo studies included comparison with healthy subjects after alcohol intake, with excessive drinkers without liver disease and with chronic alcoholics with confirmed cirrhosis. In vitro depression of polynuclear neutrophilic function was observed only with significantly higher concentrations of ethanol than encountered clinically. In social and excessive drinkers, phagocytosis was decreased but there was no change in bactericidal activity. On the other hand, in cirrhotic alcoholics chemotaxis, phagocytosis and bactericidal activity were all significantly reduced. A direct action of alcohol alone on polynuclear function would not seem to be the cause of the increased risk of bacterial infection of chronic alcoholics.

Adult↗
PubMed1985

Polymorphonuclear dysfunction in bronchopulmonary diseases in human adults.

Polymorphonuclear (PMN) functions were assessed in 55 patients with asthma or bronchial bacterial infection to evaluate the systemic phagocyte capability of patients with bronchopulmonary diseases. Random migration, nitroblue tetrazolium dye reduction, and Candida killing activity were markedly decreased in the 2 types of patients studied. PMN dysfunction was more pronounced in the most affected and heavily treated patients. Considering both the rare occurrence of congenital polymorphonuclear defects and the age of the patients studied we concluded that the PMN abnormalities observed were secondary to the onset of respiratory disease. This impairment of circulating phagocytes may contribute to the rise of a systemic susceptibility to infection able to aggravate the underlying bronchopulmonary disease.

Adult↗
PubMed1983

Impairment of polymorphonuclear functions in hospitalized geriatric patients.

Polymorphonuclear (PMN) functions were assessed in 93 non-selected hospitalized patients, 32 active, healthy, elderly controls and 29 young controls. The results confirm the impairment of PMN functions in the aged. However, PMN functions in hospitalized older persons are similar to those in non-institutionalized controls, and underlying diseases and treatment do not seem to aggravate the PMN impairment. Thus, it can be assumed that the frequent and severe infections afflicting the hospitalized aged are due to the alteration of the other host-defense mechanisms.

Aged↗
PubMed1983

[Monitoring anticoagulant treatment with the KEM-O-MAT 2HP autoanalyzer].

Synthetic chromogenic substrates were adapted to KEM-O-MAT 2HP for an automated monitoring of anticoagulant treatments, determination of factor X (S 2337) in oral anticoagulation, anti-Xa (Hepachrom) and anti-lla (S 2238) activities of heparin in prophylactic and curative heparin therapies. In all cases, these methods revealed high sensitivity, reproducibility, and a good correlation of their results with those of classical clotting assays. The present cost of synthetic substrates seriously limits the potential value of chromogenic assays for routine controls. However, the development of automated amidolytic techniques should provide an easier standardization in the laboratory control of anticoagulant treatments.

Anticoagulants↗
PubMed1983

[Evaluation of Owren's thrombotest in the monitoring of treatment with antivitamin K].

The need to standardize the monitoring of oral anticoagulant treatments has led some countries to adopt, generally, Owren's Thrombotest. Apart from needing only one reagent and being perfectly adapted to this type of monitoring, the thrombotest has the advantage of being able to be used on capillary blood and venous blood and of not being influenced by the storage of the blood samples. Its disadvantages are that it is slow to perform, difficult to automate and that it has a therapeutic range which is narrow and close to the limits of precision of the technique. The results of the Thrombotest correlate well with those of the Quick test, the activated cephalin time and the X level measured by the amidolytic technique. Until the chromogenic assays are developed, the Owren's Thrombotest provides a better homogeneity and standardization of the results coming from different laboratories.

Anticoagulants↗
PubMed1982

Polymorphonuclear functions in Hodgkin's disease patients at diagnosis, in remission, and in relapse.

Five tests investigating different aspects of the nonspecific defense mechanisms including capillary tube random migration, particle ingestion activity, quantitative and histochemical nitroblue tetrazolium dye reduction by polymorphonuclear neutrophils, and serum lysozyme concentrations were performed in 46 patients with Hodgkin's disease. The anomalies observed in the active stage of the disease consisted of a decreased random migration, a high level of serum lysozyme, and an increased nitroblue tetrazolium reduction by resting phagocytes associated with a decrease in nitroblue tetrazolium reduction by stimulated phagocytes. The particle ingestion activity was normal. The serum lysozyme assay was the only test observed to normalize in the group of patients in remission. Its determination, therefore, offers an additional means of evaluating disease activity.

Adolescent↗
PubMed1981

Polymorphonuclear functions and aging in humans.

To determine whether normal aging interferes with the functional capability of polymorphonuclear leukocytes (PMNs), 6 tests of PMN function were performed in 285 healthy subjects whose ages ranged from 20 to 97 years. A second selection based upon blood measurement and a review of medical histories 6 months later, eliminated 68 subjects. The 217 remaining persons were sub-classed by age into 7 groups including equal numbers of males and females. The functional properties of PMNs in the aged, when compared to those of younger adults, were characterized by: (a) a decrease in the chemotactic response in the 80+ age group: (b) increased adherence, with onset after age 70, maximal after age 80; (c) a progressive decrease of NBT dye reduction capability, up to age 70-79, followed by an unexplained increase of the mean value after age 80; (d) diminished Candida-killing activity, appearing in the 60+ group and becoming lowest in the oldest group; and (e) lack of changes in spontaneous migration and endocytosis. The mechanisms by which this impairment occurs are hypothetical. It is proposed that normal PMNs, after leaving the bone marrow, are influenced by various humoral components such as metabolic byproducts or immune processes altered by aging. Thus the defective PMN may represent only another victim of the aging process.

Adult↗