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Biomedical subjects

D Blanchard

Publications and source records attributed to D Blanchard.

At least 55 records · Page 3Linked to original sources

Geometric features of coronary artery lesions favoring acute occlusion and myocardial infarction: a quantitative angiographic study.

OBJECTIVES: We sought to identify the angiographic predictors of a future infarction, to study their interaction with time to infarction, patient risk factors and medications, and to evaluate their clinical utility for risk stratification. BACKGROUND: Identification of coronary lesions at risk of acute occlusion remains challenging. Stenosis severity is poorly predictive but other stenosis descriptors might be better predictors. METHODS: Eighty-four patients with an acute myocardial infarction and a coronary angiogram performed within the preceding 36 months (baseline angiogram), and after infarction were selected. All coronary stenoses (from 10% to 95% lumen diameter reduction) at baseline angiogram were analyzed by computer-assisted quantification. Each of the 84 lesions responsible for the infarction (culprit) was compared with the nonculprit stenoses (controls) in the same patient. RESULTS: Culprit lesions were more symmetrical (symmetry index +15%; p < 0.001), had steeper outflow angles (maximal angle +4 degrees; p < 0.001), were more severe (percent stenosis +5%; p = 0.001) and longer (+ 1.5 mm, p = 0.01) than controls. The symmetry index and the outflow angles were the two independent predictors of infarction at three-year follow-up. Stenosis severity predicted only infarctions occurring within 1 year after angiography. In moderately severe stenoses (40% to 70% stenosis), stratification using the symmetry index and outflow angles accurately predicted lesions remaining free of occlusion and infarction at three-year follow-up. CONCLUSIONS: Better characterization of stenosis geometry might help to understand the pathophysiologic mechanisms triggering coronary occlusion and to stratify patients for improved care.

Coronary Angiography↗

Soluble CD44: quantification and molecular repartition in plasma of patients with colorectal cancer.

Based on the important role of CD44 in tumour progression and metastasis, we evaluated, in a prospective study, plasma-soluble CD44 (sCD44) as a serum marker in colorectal cancer. Blood plasma specimens from 89 patients with colorectal neoplasm, 22 patients with a gastrointestinal disease and 23 healthy donors were analysed for quantitation (ELISA assay) and purification of sCD44. The concentration of sCD44, indicating the concentration of all isoforms, was significantly higher in patients with colorectal cancer and intestinal disease than in normal individuals, but no significant differences were found between the two groups. We found no association between plasma levels and staging of the colorectal cancer patients according to Astler and Coller. A two-step batch purification combining ion exchange and immunoaffinity chromatography, followed by Western blot analysis, revealed a complex pattern with a major band corresponding to the standard form of CD44 and minor bands that may correspond to larger variant forms. No particular sCD44 isoform was clearly associated with anatomopathological or biological information.

Aged↗

Fine specificities of murine anti-Mg monoclonal antibodies.

The specificities of two murine anti-Mg monoclonal IgG1 antibodies, 3B10 and 2D5, were determined by pepscan analysis. The peptides which correspond to various fragments of amino-terminal portions of glycophorin A of group M (GPA-M), N (GPA-N) and Mg (GPA-Mg), and replacement analogues of some of these peptides, were synthesized on plastic pins and tested for binding of the antibodies. Both antibodies bound strongly to the N-terminal Mg octapeptide 1LSTNEVAM8, but they showed different subspecificities. The essential fragment of the epitope 2D5 are amino acid residues 2STNEV6. Replacement of any of these amino acid residues by Ala, and replacement of Glu5 residue by Gly, abolished or strongly reduced the antibody binding, but replacement of Asn4 by Thr gave only a moderate decrease of peptide activity. In contrast, the Leu1 and Asn4 residues were most essential components of the epitope 3B10, while Ser2, Thr3 and Glu5 seemed to be less important. Our present results and earlier ones on the specificity of human anti-Mg alloantibodies and monoclonal anti-M/Mg antibodies showed that antibodies reacting with Mg antigen recognize different fragments and/or different amino acid residues of the amino- terminal nonglycosylated domain of GPA-Mg. The knowledge of fine specificities of antibodies reacting with Mg antigen is interesting in view of the presence of anti-Mg alloantibodies in 1-2% of human sera.

Amino Acid Sequence↗

Flow cytometric monitoring of red blood cell chimerism after bone marrow transplantation.

Chimerism after bone marrow transplantation (BMT) was investigated by flow cytometry analysis of red blood cells (RBCs) and of reticulocytes using a series of selected monoclonal or polyclonal antibodies directed against ABO, Rhesus, Kell, Duffy or MNSs antigens. The method allows the routine detection of less than 0.1% of positive cells in artificial mixed field populations. Blood samples from 135 patients undergoing BMT were investigated around days 15, 30, 45, 60, 90, 180, and then every 6 months after transplantation. Characteristic patterns showing expression of donor red blood cell antigens (expansion markers) and concomitant decrease of recipient specific antigens (depletion markers) within days 16-20 were observed for 125 successfully engrafted patients. Distinct patterns were obtained in 10 patients. A delay in engraftment was evidenced in four patients by the absence of chimerism during the first 6 months without any sign of relapse. Re-appearance of recipient RBCs and reticulocytes was observed in five patients; it was consistent with relapse that was later confirmed by clinical, haematological and cytogenetic studies. Finally, a stable and partial chimerism with 20% of RBCs expressing a marker from the recipient was observed in one patient without any sign of relapse. The reported investigation demonstrated that flow cytometry of RBCs and reticulocytes represents a powerful method to efficiently monitor bone marrow transplanted patients on a long-term basis.

Adolescent↗

The murine monoclonal antibody NaM26-4C6 identifies a common structure on band 3 and glycophorin C.

The murine monoclonal antibody NaM26-4C6 (IgM class), obtained from the splenocytes of a BALB/c mouse immunized with human umbilical cord red blood cells, was characterized by agglutination test and immunoblotting analysis. The structure of the NaM26-4C6 epitope was further elucidated by using a series of peptides synthesized on pins. The antibody agglutinated untreated and chymotrypsin-treated but not trypsin- or neuraminidase-treated human erythrocytes. Agglutination-inhibition test demonstrated that the antibody recognizes an epitope located on the N-terminal trypsin-sensitive portion of glycophorin C. The antibody bound on immunoblots to glycophorin C, and also to the band 3 protein and its 69-kDa N-terminal fragment but did not bind to desialylated and de-O-glycosylated glycophorin C. Peptide mapping allowed localization of the binding site on the 23-kDa N-terminal intracellular peptide of band 3. The antibody binds to the amino-acid sequences 22EDPDIP27 of band 3 protein and 15SLEPDPGM22 of glycophorin C, and residues D and P were found to be essential. The new epitope identified by NaM26-4C6 corresponds to a linear amino acid sequence located on the N-terminal intracellular portion of band 3 and to a more complex structure involving oligosaccharide chains on the N-terminal extracellular domain of GPC.

Animals↗

A student-developed tool for assessing safety in schizophrenic patients.

Schizophrenia is a chronic, disabling disease of mind and behavior. Since some schizophrenics are prone to violence, nursing students devised a safety risk assessment tool to help health care personnel screen clients in acute care settings who may be at risk for violent behavior. The tool is accurate, quick, and user-friendly, and it enhances communication among members of the multidisciplinary health care team. The results obtained from the assessment tool guide nurses and other health care team members in implementing appropriate interventions. Future research and pilot studies are warranted to increase the reliability and validity of this tool.

Humans↗

Relation between severity of coronary artery disease, left ventricular function and myocardial infarction, and influence of the ACE I/D gene polymorphism.

Left ventricular (LV) systolic function is partly determined by severity of coronary artery disease and is improved by angiotensin-converting enzyme (ACE) inhibition, at least in post-infarct patients. Because the ACE insertion/deletion (I/D) gene polymorphism is associated with circulating and tissue ACE activity, we sought to evaluate the role of this genetic variant on LV function in patients studied with coronary angiography, taking into account coronary vessel anatomy and history of infarction. Coronary artery disease extent scores, coronary artery patency, and LV ejection fraction were assessed in 400 consecutive Caucasian patients referred for established or suspected ischemic heart disease. A previous infarction had occurred in 141 patients an average of 3.7 years before the study. The ACE DD genotype, compared with the ACE ID/II genotype, was associated with a 2.7% higher ejection fraction in noninfarct patients (p = 0.047) but a 5.0% lower ejection fraction in post-infarct patients (p = 0.047). An interaction effect between the ACE I/D gene polymorphism, the infarction status, and LV ejection fraction was observed in the whole population (p = 0.003), in patients with no disease and 1-, 2-, and 3-vessel diseases (p = 0.03 and p = 0.06, respectively), and in those with chronically occluded coronary vessels (p = 0.02). The influence of the ACE I/D gene polymorphism on LV function is modulated by infarction status and coronary anatomy.

Aged↗

New method for quantitative determination of fetal hemoglobin-containing red blood cells by flow cytometry: application to sickle-cell disease.

A new method to quantify red blood cells (RBCs) containing fetal hemoglobin (HbF), or F cells, by flow cytometry was developed. The use of formaldehyde as fixative agent and sodium dodecyl sulfate (SDS) to permeabilize fixed RBCs resulted in a low staining background, a negligible Hb leakage, and minimal cell clumping. HbF was detected by immunofluorescence with a murine monoclonal antibody directed to the gamma chain of human Hb. The accuracy of the F-cell count was evaluated on mixed-field populations of adult and cord RBCs. The results of flow cytometry were highly correlated with HbF dosage in the hemolysate by high-pressure liquid chromatography (HPLC) (R > 0.99). The sensitivity of the method allowed the study of HbF distribution at the single-cell level in normal controls and patients with sickle-cell disease (SCD). All patients exhibited a heterocellular distribution of HbF, with highly variable percentages of F cells and non-F cells. As an additional and valuable biological parameter in SCD, the mean HbF content per F cell could be deduced from the measurement of HbF level by HPLC and F-cell count by flow cytometry. Results were unchanged after storing the cells for several weeks in an optimized resuspending solution. Since it does not need uncommon reagents or devices and allows the simultaneous detection of membrane antigens by two-color flow cytometry, this method is convenient for routine laboratories as well as for research purposes.

Adult↗

Use of anti-GP IIb-IIIa in acute thrombosis after intracoronary stent implantation.

Acute occlusion of coronary stents still occurs in 0.5-2% of patients. The usefulness of GP IIb-IIIa receptor inhibitors has never been evaluated in this indication. After 1,454 stent implantations, acute occlusion occurred in 16 patients. Direct percutaneous transluminal coronary angioplasty (PTCA) was immediately performed. In eight patients, no recurrent thrombosis occurred during the 15 min following PTCA, and abciximab infusion was started after this period. In six patients, immediate recurrent thrombosis occurred in the stent. In these cases, an intravenous bolus of abciximab followed by a new inflation at low pressure was performed. Fifteen min after the bolus, stable TIMI 3 flow was restored in all six cases, and no thrombus or haziness remained. In two patients, a TIMI 0 flow persisted despite PTCA and the use of a bolus of abciximab. No recurrent ischemic symptoms were observed before hospital discharge. Abciximab in combination with balloon angioplasty can be used safely to control acute thrombosis after stent deployment.

Abciximab↗

Percutaneous transluminal angioplasty of radial artery grafts.

The radial artery is being used with increasing frequency to replace the saphenous vein as a coronary artery bypass graft, in the belief that it will provide improved long-term patency. Several centers have confirmed that the early results of surgery using the radial artery seem to be better than those obtained with saphenous grafts. Despite these apparent gains, early failure of the radial artery graft can occur and is frequently associated with symptomatic myocardial ischemia. Percutaneous angioplasty is an alternative to reoperation to treat lesions occurring on radial artery grafts. We report on 4 patients who underwent angioplasty of radial artery grafts.

Aged↗

Investigation of the survival of paroxysmal nocturnal hemoglobinuria red cells through the immunophenotyping of reticulocytes.

BACKGROUND: Complement-mediated lysis of red cells (RBCs) is a classic feature of paroxysmal nocturnal hemoglobinuria (PNH) that is traditionally studied with a combination of radiolabeling of RBCs and in vitro hemolysis tests. Phenotyping of reticulocytes was used as an alternative method for the evaluation of the relative life span of normal RBCs (PNH I) and RBCs that were partially (PNH II) or completely (PNH III) deficient in CD59. STUDY DESIGN AND METHODS: Murine monoclonal antibodies CD55, CD58, and CD59 and thiazole orange were used to phenotype reticulocytes by two-color flow cytometry in nine PNH patients. RBC survival could be calculated from the ratio of CD59- or CD59low mature RBCs to CD59- or CD59low reticulocytes obtained from these patients who had not received a transfusion. RESULTS: The life span of PNH III RBCs varied from about 17 to 60 days. PNH II reticulocytes were found in the four patients with PNH II RBCs. The life span of PNH II RBCs varied with their residual expression of CD59, and cells with 15 to 20 percent of the normal amount of CD59 were protected against in vivo hemolysis. CONCLUSION: Phenotyping of reticulocytes is a convenient and reliable tool for evaluating the relative survival of normal and PNH RBCs. PNH II and PNH III reticulocytes are phenotypically distinct, and some PNH II RBCs may be sensitive to complement-mediated lysis in vitro, but normally they are complement-resistant in vivo.

CD55 Antigens↗

Shared epitopes of glycoprotein A and protein 4.1 defined by antibody NaM10-3C10.

We have produced the murine monoclonal antibody (MAb) NaM70-3C10 (IgM) from splenocytes of mice immunized with human red blood cells (RBCs). The MAb agglutinated untreated as well as trypsin, chymotrypsin, neuraminidase, or ficin-treated RBCs from controls. In contrast, control RBCs treated with papaine or bromelaine were not agglutinated. On immunoblots, the MAb bound to glycophorin A (GPA) and to a 80 kDa protein identified as protein 4.1. Analysis by agglutination of variant RBCs carrying hybrid glycophorins made of the N-terminus (amino acids 1-58) of GPA and of the C-terminus (amino acids 27-72) of glycophorin B (GPB) and competition-inhibition test using purified GPA and a synthetic peptide corresponding to the amino acid sequence 48-58 of GPA demonstrated that the epitope is located within residues 48-58 of GPA. Epitope analysis with immobilized peptides showed that the MAb recognizes the sequence 53Pro-Pro-Glu-Glu-GIu58 of GPA. A homologous sequence is also present within amino acids 395 to 405 of protein 4.1. Finally, the MAb bound to 16 kDa chymotryptic peptide of protein 4.1, which carries the above amino acid sequence. In conclusion, it may be assumed that NaM70-3C10 specifically recognizes a common epitope on the extracellular domain of GPA and on the intracellular protein 4.1; this specificity explains the persistence of the 80 kDa band on blots when RBCs are treated with papain.

Amino Acid Sequence↗

Characterization of a murine monoclonal antibody specific for swine beta1 integrin.

Murine monoclonal antibodies were raised against porcine platelets in order to provide tools for investigating interactions of human blood cells and natural antibodies with porcine tissues. Hybridomas were screened by cellular ELISA on porcine platelets and endothelial cells. Positive clones were tested by flow cytometry for reactivity with isolated endothelial cells. One clone, NaM160-1A3, produced an antibody that stained porcine but not human endothelial cells and lymphocytes. The antibody bound to a 116 kDa glycoprotein on Western blot of both platelets and endothelial cells. The antigen was purified from a platelet lysate by affinity chromatography, first on a ConA column and then on a column presenting the immobilized NaM160-1A3 antibody. Two glycoproteins were obtained: one (116 kDa) was recognized by the antibody and one (150 kDa) was not. The 116 kDa protein had an internal decapeptide identical with human beta 1 integrin, and the 150 kDa protein had an internal amino acid sequence belonging to porcine alpha 2 integrin. Therefore, the NaM160-1A3 antibody was directed against porcine beta 1 integrin and allowed the purification of the complex alpha 2 beta 1, also termed Very Late Antigen 2 (VLA-2). It did not recognize human beta 1 integrin.

Amino Acid Sequence↗

Phase variation in Helicobacter pylori lipopolysaccharide.

Helicobacter pylori NCTC 11637 lipopolysaccharide (LPS) expresses the human blood group antigen Lewis x (Le(x)) in a polymeric form. Le(x) is beta-D-galactose-(1-4)-[alpha-L-fucose-(1-3)]-beta-D-acetylglucosamine. Schematically the LPS structure is (Le(x))n-core-lipid A. In this report, we show that Le(x) expression is not a stable trait but that LPS displays a high frequency (0.2 to 0.5%) of phase variation, resulting in the presence of several LPS variants in one bacterial cell population. One type of phase variation implied the loss of alpha1,3-linked fucose, resulting in variants that expressed nonsubstituted polylactosamines (also called the i antigen), i.e., Le(x) minus fucose; LPS: (lactosamine)n-core-lipid A. The switch of Le(x) to i antigen was reversible. A second group of variants arose by loss of polymeric main chain which resulted in expression of monomeric Le(y); LPS: (Le(y))-core-lipid A. A third group of variants arose by acquisition of alpha1,2-linked fucose which hence expressed Le(x) plus Le(y); LPS: (Le(y))(Le(x))n-core-lipid A. The second and third group of variants switched back to the parental phenotype [(Le(x))-core-lipid A] in lower frequencies. Part of the variation can be ascribed to altered expression levels of glycosyltransferase levels as assessed by assaying the activities of galactosyl-, fucosyl-, and N-acetylglucosaminyltransferases. Clearly phase variation increases the heterogeneity of H. pylori, and this process may be involved in generating the very closely related yet genetically slightly different strains that have been isolated from one patient.

Amino Sugars↗

[Long-term results of aorto-bifemoral prostheses in the surgery for atheromatous stenosis of the aortic bifurcation].

Seven hundred patients operated consecutively by the same surgical team for atheromatous stenosis of the aortic bifurcation were followed up for 20 years with only 5 patients lost to follow-up. There were 94.5% of men with a mean age of 58 years. The operative mortality was 2.7% with few deaths due to true cardiovascular causes (0.7% of patients). The secondary mortality was very high with two main causes: cancer (39% of patients) and cardiovascular diseases (37%). Other causes were responsible for only 24% of deaths. The principal complications of the prostheses were: infection (0.6% of operated patients), thrombosis (6.7%), pseudo-aneurysm of the aorta (1.57%) and pseudo-aneurysm of Scarpa's triangle (4%). The benefits of surgery are unquestionable both on terms of survival, as amputation, bed confinement and invalidity are avoided, and in terms of function, as amputation was avoided in 84% of the 32% of patients in Stages III or IV before surgery. Only 5% of patients were amputed during the observation period. Moreover, 79% of survivors had a good functional result at 15 years. Improvement of results depends on better hygienic measures, systematic screening for high risk cancers and a better management of the arterial disease with early treatment of other arterial diseases (coronary, carotid) in order to reduce postoperative and mostly medium- and long-term cardiovascular mortality.

Aged↗