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P Poncelet

Publications and source records attributed to P Poncelet.

At least 37 records · Page 2Linked to original sources
PubMed1996

Quantitation of hemopoietic cell antigens in flow cytometry.

Using appropriate standards immune flow cytometry permits quantitative analysis of the expression levels of cellular antigens. This information can be gained on an absolute basis and reported in terms of numbers of molecules per cell. This offers clues for reaching time-to-time and lab-to-lab comparability of immuno-fluorescence data. After briefly reminding the characteristics of available standards this paper provides an overview of the main relevant candidate molecules for flow cytometric quantitation on hemopoietic cells and reviews the major fields of application in immuno-hematology.

Animals↗
PubMed1996

[Presentation of OCTAVE II. A current epidemiologic study in France of the added prognostic value of ambulatory blood pressure monitoring].

The diagnosis of "white coat" hypertension, the measurement of indices of 24 hour variability of the blood pressure and increased accuracy of blood pressure estimation are some of the advantages of ambulatory blood pressure monitoring. They are part of the reason why the method has been adopted by ambulatory blood pressure monitoring is really useful in the treatment of hypertension is fragile: although the correlation with target organ complications seems better than with conventional blood pressure measurement, it remains to be shown that this information helps to predict and then improve the prognosis of hypertension. With respect to this first stage of demonstration of the added prognostic value attributable to ambulatory blood pressure monitoring, several studies have been undertaken, one of which is OCTAVE II. The goals were to analyse the predictive values of the indices obtained by ambulatory blood pressure monitoring in terms of cardiovascular morbidity and mortality after having described the correlations between these indices and the characteristics of individual patients. Two hundred and sixty six cardiologists, members of the French College of Cardiology, included 3,569 patients in whom an indication for ambulatory blood pressure monitoring had been retained, over a period of 10 months in 1991. These patients were 56.4 year old on average, with 52.6% men, hypertensive or not. The 5 year follow-up should end at the beginning of 1997.

Blood Pressure↗
PubMed1995

A mouse monoclonal antibody specific for the V beta 5.3 chain of the human TcR recognizes a subgroup of the mouse TcR V beta 8.2 chains.

We have analyzed the reactivity of a mouse monoclonal antibody directed against the human T cell receptor for antigen (TCR). This antibody (111-427) of immunoglobulin G1 isotype has been produced in a BALB/c mouse immunized with HPB-ALL cells and normal human peripheral blood leukocytes. It reacts specifically with the HPB-ALL lymphoma and 2 to 7% of normal human blood lymphocytes, on which it has a mitogenic effect in vitro. We have shown that it immunoprecipitates the alpha beta TCR of HPB-ALL and that it is specific for the V beta 5.3 chain of the human TCR. In addition, we have observed that this antibody stains a minor fraction of T lymphocytes in different strains of mice. We have screened a number of murine T cell clones or hybridomas and have found that the T cell hybrid line DO.11.10.S4.4 is positive. We have been unable to immunoprecipitate reproducibly the molecule recognized by 111-427 after 125I cell surface labeling and cell lysis in NP-40 or digitonin, probably because of low-affinity binding. On Western blotting, 111-427 revealed one band that has an apparent molecular mass of 89 kDa in nonreducing conditions and disappears after reduction. Similar results were obtained in parallel with the F23.1 and F23.2 antibodies. Thus, this antibody appears to recognize an epitope present primarily on the V beta 8.2 chain of the mouse TCR. We have assayed its capacity to stimulate splenic T lymphocytes in vitro. We have observed that it is capable of triggering, to a minor degree in soluble form and very effectively when coupled to Sepharose beads, the proliferation of spleen T lymphocytes from mice chronically infected with the blood parasite Trypanosoma cruzi.

Amino Acid Sequence↗
PubMed1995

[Ambulatory blood pressure monitoring and clinical trials].

Ambulatory blood pressure monitoring (ABPM) is now widely used for the assessment of antihypertensive drugs. This procedure may be used in phase II studies in dose-ranging evaluations as well as in phase III in order to assess the drug efficacy in the patient's natural environment. The increase in the reproducibility related to the repetition of blood pressure measurements by ambulatory monitoring may improve the accuracy of the trial and minimize the numbers of subjects required. Placebo fails to lower ambulatory blood pressure in almost all studies. Nevertheless, placebo is always necessary in clinical studies with ABPM at least for the pre-inclusion phase and in order to study the peak-trough ratio. This ratio may be accurately assessed by ABPM. Finally, ABPM may be useful to rule out "white coat" responders, who are not really hypertensive patients.

Antihypertensive Agents↗
PubMed1995

Non-invasive ambulatory blood pressure variability and cardiac baroreflex sensitivity.

AIM: The objective of this study was to evaluate the relationship between non-invasive ambulatory blood pressure variability and cardiac baroreflex sensitivity in hypertensive patients. SUBJECTS AND METHODS: Ambulatory blood pressure measurements (15-min intervals for 24 h) and continuous blood pressure measurements (Finapres, 20 min at rest after a 10-min resting period) were performed in 123 untreated hypertensives (resting diastolic blood pressure > or = 90 mmHg; 80 males, 43 females; mean +/- SD age 49 +/- 12 years, range 19-73). Fourier series were used to model 24-h blood pressure profiles (four harmonics). Ambulatory blood pressure variability was assessed by determination of the residuals in each 24-h blood pressure profile (measured minus predicted pressures). Resting blood pressure variability was defined as the SD of the mean Finapres value. Baroreflex sensitivity was evaluated by automatic detection of blood pressure and pulse interval sequences of > or = 3 beats when systolic blood pressure and pulse interval sequences changed in the same direction (increase or decrease: 1 mmHg for systolic blood pressure and 4 ms for RR interval), and was assessed as the slope of the regression line for each sequence. RESULTS: Ambulatory systolic blood pressure variability increased with age (r = 0.28*) and systolic pressure (r = 0.44**). Baroreflex sensitivity (increasing systolic pressure/pulse interval) decreased significantly with age (r = -0.48**) and systolic pressure (r = -0.23**), and was significantly related to increased ambulatory blood pressure variability (r = -0.33**). In a multivariate stepwise analysis the relationship between ambulatory blood pressure variability and baroreflex sensitivity (increasing systolic pressure/pulse interval) was statistically independent of age and systolic pressure (R = 0.55, P<0.001); this relationship was not observed with the corresponding decreasing sequence. CONCLUSIONS: This study shows that in uncomplicated hypertension, ambulatory blood pressure variability is related to baroreflex sensitivity independently of the blood pressure level. This finding has prognostic implications for this non-invasive measurement, which needs to be confirmed by large longitudinal studies.

Adult↗
PubMed1994

CD23 antigen density is related to serum gamma globulin level, bone marrow reticulin pattern, and treatment in B chronic lymphocytic leukemia.

The CD23 antigen density was evaluated by a cytofluorometric technique in 55 patients with chronic lymphocytic leukemia. The quantification method was based on the use of biological standards in indirect immunofluorescence. The CD23 antigen density was correlated with the percentage of CD23 positive cells, but antigen density appeared to be a more informative parameter. CD23 antigen density was lower in stage B than in stages A or C patients, and higher in patients undergoing chemotherapy or previously treated than in untreated patients. There was a significant negative correlation between CD23 antigen density and serum gamma globulin and IgG levels, that existed only in patients in an advanced stage of the disease. CD23 antigen density was higher in patients with abnormal bone marrow reticulin pattern. Serum gamma globulin level was lower in these patients, as well as in patients with prognostically unfavorable histologic bone marrow infiltration pattern. These data emphasize the interest of antigen density as an additional parameter and the complex relationship between CD23 expression, hypogammaglobulinemia, bone marrow histologic findings, and treatment in chronic lymphocytic leukemia.

Antibodies, Monoclonal↗
PubMed1994

[Blood pressure variability and stimulation tests: value of the Stroop word color conflict test].

OBJECTIVES: To study the modifications of the BP and its short-term variability in hypertensives patients submitted at to a psychological stress test. DESIGN AND METHODS: Fourty nine hypertensive subjects (27 women and 22 men, aged 46 +/- 9, SBP 164 +/- 10, DBP 97 +/- 6 mmHg after a 15 days placebo run-in period) were studied. We used the original version of Stroop Word Color Conflict Test (SWCCT) to induce mental stress. Haemodynamic parameters (SBP, DBP, MPB and HR) were measured continuously by a non invasive method (Finapres) with data acquisition every 0.5 second allowing spectral analysis of SBP variability at rest, during and after SWCCT (FFT algorithm on 256 point time series Anapres 1.2). RESULTS: All haemodynamic parameters increased during stress test (p = 0.001). The mean value and the variability (V) of SBP standard deviation (SD) increased during SWCCT (p = 0.001 and p = 0.003 respectively). Two minutes after the test, SPB returned to the rest level, while the overall variability of SPB remained elevated (p = 0.007). Spectral analysis: the total area under the curve and the mid frequency component (MFC) (66-128 mHz) increased during and after SWCCT (p = 0.001). [table: see text] CONCLUSION: Short-term variability of SBP is increased in hypertensives when submitted to a SWCCT appears to induce sustained orthosympathetic stimulation as suggested by the increase of mid frequency component (Mayer waves).

Adult↗
PubMed1994

Quantification of CD24 and CD45 antigens in parallel allows a precise determination of B-cell maturation stages: relevance for the study of B-cell neoplasias.

Quantitative expression, i.e. absolute number of monoclonal antibody molecules bound per cell, was evaluated for CD24 and CD45 by flow cytometry with standards of fluorescence intensity on a panel of normal and neoplastic B cells. The CD24 antigen was expressed at homogeneous high level in fetal bone marrow and liver. Its density decreased progressively in the other normal tissues in parallel with the B-cell maturation. The ratio between CD24 density measured on fetal bone marrow B cells and that seen on adult peripheral B cells was 6:1. The CD45 antigen density was lower on fetal bone marrow cells than in the more mature stages. Fetal spleen lymphocytes and all the mature B lymphocytes displayed the same CD45 density than that seen on normal adult peripheral T cells. The CD24/CD45 antigen density ratio was precisely related to the stage of B-cell maturation. The same pattern of variation of CD24 and CD45 antigen density was seen on B-cell neoplasias, with a significantly higher value of CD24 and lower value of CD45 in acute lymphoblastic leukemias than in chronic malignancies. CD24 and CD45 antigen levels were frequently out of the range observed in the corresponding normal population. Among ALL patients, a low CD24/CD45 antigen density ratio was associated with a good prognosis. These data confirm the interest of an absolute quantitative study for widely distributed antigens.

Antigens, CD↗
PubMed1993

[Is scheduled hospitalization over a specific period still justified in hypertension?].

To general practitioners' request, a 36-hour scheduled hospitalization over a determined period (SHDP) was set up to assess the effects and the etiology of the arterial hypertensions they had detected and to propose an appropriate treatment. From November 1988 to December 1990, 277 patients (156 male/121 female) with mean age of 44.7 +/- 14.5 were thus hospitalized over a determined period. All of them underwent 24-hour semi-ambulatory blood pressure monitoring (Bard Sentron) by using the oscillometric method, which permits to measure mean blood pressure (MBP) instead of calculating it. This 24-hour MBP was on average of 108.5 +/- 16.2 mmHg and not significantly different from daytime MBP (111 +/- 16.3 mmHg). Figures of MBP superior to 105 mmHg confirmed permanent HBP (High Blood Pressure). On the 277 patients, 46 (16%) had a normal MBP, 67 (24%) had a "borderline" MBP (between 96 and 105 mmHg). A severe HBP (MBP > 125 mmHg) found in 66 cases (23%) was confirmed by visceral impairment. Left ventricular hypertrophy (LVH) was detected in 12 cases (4.3%) on the chest radiograph, in 24 cases (8.6%) on the ECG and in 75 cases (27%) on the echocardiogram. The etiological assessment revealed 10 cases (3.61%) of secondary hypertension with 3 reno-vascular HBP and 2 Conn's adenomas. Eventually, therapeutic abstention was recommended in 57 patients (20.5%) though 20 of them had previously received antihypertensive therapy. All in all, SHDP permits a more accurate determination of the consequences and severity of HBP. The small number of secondary HBP reflects the proportion found in practice.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Rapid isolation of human endothelial cells from whole blood using S-Endo1 monoclonal antibody coupled to immuno-magnetic beads: demonstration of endothelial injury after angioplasty.

The presence in whole blood of circulating endothelial cells (EC) has been a subject of debate for many years. It could represent a good marker of vessel injury. We demonstrate here that human endothelial cells can be directly isolated and identified in circulating blood by means of an endothelial cell specific monoclonal antibody, S-Endo1, coupled to micromagnetic beads. The specificity and efficacy of the assay were established using normal blood samples with cultured EC added. Specific rosettes formed between EC and beads could subsequently be isolated with a magnet. The rosetted cells were recovered with a yield greater than 80%. Their endothelial origin was confirmed by the positive labelling of von Willebrand factor and thrombomodulin, as well as the presence of Weibel-Palade bodies. We applied this method to demonstrate significantly increased levels of EC in venous and arterial human blood samples in patients undergoing heart catheterization. This new whole blood immuno-separation method may be useful in determining endothelial cell injury in vascular disorders.

Antibodies, Monoclonal↗
PubMed1992

A new marker on chicken hematopoietic cells is defined by a monoclonal antibody raised against a V beta chain of the human TCR.

In this paper, we show that a mouse monoclonal antibody, 111-427, specific for the V beta 5.3 chain of the human T-cell receptor (TCR) for antigen, also reacts with chicken hematopoietic cells. Our data indicate that the majority of 111-427 positive cells among peripheral blood leucocytes (PBL) are thrombocytes. This antibody also recognizes two in vitro cell lines, III-C5, and IL-2-dependent T-cell line and HD11, a macrophage cell line. In addition, erythrocytes and a minor subpopulation of thymus and spleen cells are also stained by the monoclonal antibody (mAb). No specific immunoprecipitation could be detected from 125I radiolabeled cell lysates. By Western blotting techniques, the 111-427 mAb identifies a single band of apparent molecular weight 91 kD, unaffected by reduction, from III-C5 and HD11 cell lysates. This band is absent in negative cell control lysates. On thrombocytes, the apparent molecular weight of the band is shifted to 87 kD. These results indicate that the mAb does not recognize the chicken T-cell receptor for antigen, but a cell surface marker shared primarily between thrombocytes and erythrocytes. This new chicken cell marker is compared to other cell surface markers in avian or mammalian species that present some analogies in their tissue distribution.

Animals↗
PubMed1992

[Measurement of blood pressure in obese patients: reliability and value of finger measurement (Finapres)].

Indirect measurement of the blood pressure in obese persons is still inaccurate, especially if the arm circumference deeply differs from one measure point to the other, so that the use of a wide bladder is inappropriate. Some alternative solutions have been described: oscillometric device on the arm or on the forearm, different shapes of the cuff-bladder, auscultation on the radial artery with the cuff on the forearm. We tested the capability of the Finapres device which measures the finger arterial blood pressure, beat to beat, using the volume clamp method of Penâz. In six obese patients (BMI > 30, arm circumference > 35 cm) treated for hypertension were undergoing functional respiratory tests. The finger pressure was measured simultaneously with intrabrachial on homolateral arm. Blood pressure was measured at rest and after a cold pressor test. [table: see text] The use of the Finapres seems to be possible. The correlation with the systolic is excellent, where as the correlation with the diastolic is weaker; which however is usual in any diastolic correlation between non invasive and invasive device. The CPT does not modify the correlations. Moreover the Finapres allows dynamic exploration which is of particular interest in obese persons because their blood pressure is particularly variable.

Blood Pressure↗
PubMed1992

Acute monocytic leukemia: prevalent cutaneous lesions. Two cases.

The authors report two cases of acute myeloid leukemia with prevalent cutaneous lesions. The positivity of granulo-monocytic antibodies and the exclusive cutaneous site of the lesions drove them previously to the diagnosis of histiocytic sarcoma. These cases stress the problem of the immunological identification of cutaneous lymphomas of "histiocytic" type.

Aged↗
PubMed1991

Characterization of epitheloid cells from human omentum: comparison with endothelial cells from umbilical veins.

Capillary cells represent 95% of the vascular bed, and cells from large and micro-vessels do not express identical functions. In order to study the hormonal regulation of plasminogen activator inhibitor 1 (PAI-1) secretion by human capillary cells we used epithelial cells from omental tissue (HOTMEC). As their endothelial origin is subject to controversy, we attempted to determine their characteristics by comparing them to human umbilical vein endothelial cells (HUVEC). Morphological and biological criteria were studied. By phase contrast microscopy HOTMEC elicited a cobblestone pattern similar to HUVEC. Weibel-Palade bodies were not found in the cytoplasm with electron microscopy. Fluorescence microscopy studies indicated that HOTMEC took up acetylated-LDL more intensely than HUVEC, and showed no staining for von Willebrand factor. The phenotype of HOTMEC was studied by flow cytometry using monoclonal antibodies (mo Ab) directed against epitopes either specific for endothelial cells or for mesothelial cells. We showed that in our preparations only 10% of cells reacted with mo Ab specific for endothelial cells. About 60% of the HOTMEC were labelled with an antibody directed against mesothelial cells. HOTMEC expressed fibrinolytic factors. Tissue plasminogen activator (t-PA) levels in HOTMEC conditioned medium were 50 fold higher than those of HUVEC, and the PAI-1 secretions were identical in both cell types. Insulin which is known to increase PAI-1 synthesis by hepatocytes did not enhance the PAI-1 level either in HOTMEC or in HUVEC conditioned media. Our results suggested that morphological and functional methods did not allow discrimination between the cell types present in the omentum tissue.(ABSTRACT TRUNCATED AT 250 WORDS)

Cells, Cultured↗
PubMed1991

Cytofluorometric detection of human endothelial cells in whole blood using S-Endo 1 monoclonal antibody.

It has long been debated whether endothelial cells are present at very low frequency in peripheral blood. Elevated concentrations of such circulating cells may represent a good marker of vascular injury. We have therefore designed an immunocytometric assay for the detection of rare endothelial cells in whole blood. This assay is based on a new monoclonal antibody (MAb) S-Endo 1, made against human umbilical vein endothelial cells (HUVEC) and specific for endothelial cells of various origins without detectable reactivity with blood cells. First, the sensitivity of the assay was established by using normal blood samples with admixed HUVEC as an in vitro model. A good correlation was obtained between added and counted endothelial cells; the recovery was greater than 90% and the minimum detectable concentration of HUVEC was about 0.2 cells/microliters whole blood. Using this rapid counting technique, no detectable levels of endothelial cells were found in the blood of normal individuals (CE less than or equal to 0.1 cells/microliters) while elevated concentrations (up to 8 cells/microliters) were detected in a human model of vascular injury corresponding to a traumatic venepuncture. Thus, this new whole blood immunocytometric assay using S-Endo 1 MAb may be useful in determining the levels of circulating endothelial cells in vascular disorders.

Animals↗
PubMed1991

Postextrasystolic sinoatrial exit block in human sick sinus syndrome: demonstration by direct recording of sinus node electrograms.

Ten patients with sick sinus syndrome having repetitive sinus node electrograms during long postpacing pauses were studied during programmed atrial stimulation. Sinus node activity was recorded using a percutaneous catheter electrode. A sinus node electrogram was recorded before the return atrial beat in seven patients; it was similar to the sinus node electrogram observed during postpacing pauses and is clearly identified because sinoatrial conduction time was markedly prolonged following the atrial extra beat. Complete sinoatrial exit block occurred in four patients. (1) Sinus node electrograms were thus validated both during postpacing pauses and during programmed atrial stimulation in most patients with sick sinus syndrome. (2) Sinoatrial conduction time was markedly prolonged after one extrasystole, accounting for supracompensatory atrial return cycles. (3) If it were cumulative following multiple extrasystoles, this effect could constitute the electrophysiologic link between an abnormal response during programmed atrial stimulation and the complete sinoatrial block recorded during the pauses that follow rapid atrial pacing.

Cardiac Catheterization↗
PubMed1991

Surface CD4 density remains constant on lymphocytes of HIV-infected patients in the progression of disease.

In an attempt to question the influence of circulating virus, soluble gp120 or CD4 self-reacting antibodies upon results of CD4+ T-cell immunophenotyping in AIDS patients, five anti-CD4 mAb defining several epitopes of the V1 and V2 domains of the CD4 molecule were used to analyse the epitopic density of CD4 on lymphocytes of seropositive patients taken at stages II, III and IV of HIV infection, according to the Centers for Disease Control (CDC, Atlanta) classification. Our results demonstrate that each CD4 epitopic density measured on circulating lymphocytes remains constant at a mean level of 46,000 epitopes per cell whatever the stage of the disease and whatever the serum p25 concentration. These data provide evidence that antibody accessibility to several CD4 epitopes is not altered by putative interactions between CD4 molecules and circulating virus, soluble gp120 or anti-CD4 autoantibodies. If such binding events, as expected, do occur in vivo, they are of too low a magnitude to influence the immunophenotyping. Furthermore, we show that mAb specific for different epitopes in the V1 and V2 domains of the CD4 molecule can be used interchangeably for the biological followup of the CD4+ cell population in blood samples of HIV-infected patients.

Acquired Immunodeficiency Syndrome↗