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Biomedical subjects

P Alexandre

Publications and source records attributed to P Alexandre.

At least 19 recordsLinked to original sources
PubMed2001

Energy saving in flight formation.

Many species of large bird fly together in formation, perhaps because flight power demands and energy expenditure can be reduced when the birds fly at an optimal spacing, or because orientation is improved by communication within groups. We have measured heart rates as an estimate of energy expenditure in imprinted great white pelicans (Pelecanus onocrotalus) trained to fly in 'V' formation, and show that these birds save a significant amount of energy by flying in formation. This advantage is probably a principal reason for the evolution of flight formation in large birds that migrate in groups.

Animals↗
PubMed1994

Hemorheological and hemostatic parameters in children with nephrotic syndrome undergoing steroid therapy.

Disturbances in hemostatic and hemorheological parameters have been investigated in a group of 29 children with nephrotic syndrome: 23 children classified as steroid-sensitive and 6 as steroid-resistant. Studies were performed before prednisone treatment and 3 weeks later, after initiation of steroid therapy. Before treatment, the alterations in hemostatic system involved moderate thrombocytosis with spontaneous aggregation in 19 patients. High levels of fibrinogen, factor VIII, Willebrand factor, protein C, protein S and alpha 2-macroglobulin (alpha 2M) were observed. Factor XII and alpha 1-antitrypsin (alpha 1AT) were lower than normal. Antithrombin III (ATIII) level was normal in the majority of patients. A plasma and blood hyperviscosity syndrome was also observed as well as an increase in erythrocyte aggregation. During treatment, an improvement in the hemostatic parameters was observed in the patients who responded to prednisone. The expected increase in factor VIII (frequently described in the literature) was not observed, while there was a significant increase in protein C. In the steroid-resistant patients, the only significant changes observed were decreased fibrinogen and increased protein C. The hemorheological parameters showed a tendency towards normality regardless of whether or not the treatment provided remission of NS. The relationship between hemorheological and hemostatic factors changes are discussed.

Adolescent↗
PubMed1993

Interlaboratory evaluation of methods for the assay of Protein C in purified concentrates.

Determination of the quantity and activity of the Protein C molecule is of the utmost importance in highly purified concentrates prepared for replacement therapy. A multicenter study was undertaken to evaluate the comparability and accuracy of Protein C assays from commercial sources. Significant between-assay and interlaboratory differences were found for both functional and immunological assays. The interlaboratory variability is explained in part by the use of different control plasmas. The results also indicate the importance of the diluent used. This study emphasizes the need for standardized methods for determining the characteristics of Protein C concentrates.

Enzyme-Linked Immunosorbent Assay↗
PubMed1991

[Multicenter study on purified protein C concentrates and defined plasma levels].

A variety of protein C assays are available as commercial kits. A collaborative study was undertaken to evaluate the performance of protein C assays. Various samples including calibrated plasmas and high purity concentrates destined to therapy were distributed among five laboratories. This comparison of protein C assays indicates that protein C levels measured by different functional or immunological assays and by five laboratories are very close for calibrated plasmas but not for high purity concentrates. The selection of the standard and the dilution buffer for protein C concentrates have important implications for the interpretation of the results. Dilution of purified protein C concentrates in protein C deficient plasma which restaure a total protein level similar to that of normal plasma improve the accuracy of functional protein C assays.

Chromogenic Compounds↗
PubMed1988

Lymphocyte proliferative responses in haemophiliac patients: relations to clinical and immunological findings.

Blood lymphocyte proliferative responses to mitogens were studied in 65 patients with haemophilia (haemophilia A: 54 patients, haemophilia B: 11 patients) in parallel with 39 male control subjects. As a group, patients with haemophilia did not demonstrate abnormal proliferative responses to phytohaemagglutinin (PHA), Concanavalin A (ConA) and pokeweed mitogen (PWM) when compared with healthy controls. When the patients were analysed according to their seropositivity for antibody to human immunodeficiency virus (HIV), those who were positive had significantly decreased PHA, ConA and PWM responses. Haemophiliac patients with T4+/T8+ ratios less than 1 had reduced proliferative responses to PHA, ConA and PWM when compared to patients with ratios greater than 1. No significant difference in mitogen responses were found when the patients were analysed according to the presence or absence of palpable lymphadenopathy. Those patients with haemophilia A who had received more than 5 x 10(4) units of factor VIII during the two years preceding the study showed no significant difference in PHA, ConA and PWM responses when compared to patients receiving less.

Adolescent↗
PubMed1987

[Is enoxaparine (PK 10169) a good anticoagulant in chronic hemodialysis?].

Tolerance and efficacy of single i. v. injections of PK 10169 (1 mg/kg) during installation were evaluated in 10 patients with stable chronic renal insufficiency treated with 3 sessions of hemodialysis weekly (sessions of 4 and 5 hours). Tolerance was good in all cases. Efficacy was globally satisfactory (no complete coagulation) but by the 4th hour in 7 out of 30 sessions coagulation was apparent in the bubble trap with elevation of residual blood volume, recurring in the same patient but not affecting result of dialysis. In these cases anti-Xa activity was reduced from the 2nd hour and at end of dialysis, with a markedly elevated FPA level. For most patients it is possible to envisage 5-hour sessions, but in those few susceptible to develop coagulation repeated clinical surveillance of all circuit elements is necessary.

Adult↗
PubMed1987

[Thrombogenic thrombopenia related to heparin. Clinical, biological and therapeutic results. Apropos of 32 cases].

Heparin induced thrombocytopenia is characterized by often dramatic evolution of thrombotic arterial and venous complications. These occurred or are worsened in curative or preventive heparin therapy and the treatment remains delicate. The authors report 32 observations of thrombocytopenia complicated with thromboembolic events; seven deaths are to mention. The tests of platelet aggregation with standard heparin and platelets poor patient's plasma confirm the diagnosis in 28 cases of 30 very early studied and in 2 cases around the 6th day only after the stop of standard heparin. The choice of anticoagulant therapy is carried out the negative tests of platelet aggregation with low molecular weight heparin (L.M.W.H.) (CY 216, CY 222 Choay, PK 10109 Pharmuka). In L.M.W. heparin therapy, clinical and biological improvement is obtained in 26 cases of 30 treated cases. In three cases, the rapid climbing of platelet countings is not present although negative tests of platelet aggregation with selected L.M.W.H. In one case, after a initial climbing of platelet countings, the thrombocytopenia recurs rapidly with L.M.W. heparin after a operation. The immediate or secondary passage with K-antivitamins, platelet antiaggregant stabilized medium and long term's evolution.

Adult↗
PubMed1987

[Use of a low molecular weight heparin, CY 222, in the treatment of consumption coagulopathy].

UNLABELLED: Among the different treatments used for consumption coagulopathies, the most contested is classical heparin because of the risk of worsening of a hemorrhagic syndrome. A low molecular weight heparin was evaluated to determine possible improvement of this risk. METHODS: Treatment with CY 222 (Choay) was administered over 2 years to 29 patients (mean age 40 years, range 15-74) with coagulation coagulopathies. Diagnosis was based on the presence of 3 of the following 5 signs: platelets less than 150,000/mm, fibrinogen less than 2 g/l, QT less than 50%, ethanol test positive, PDF greater than 20 micrograms/ml. Etiology could be classed in 3 groups: gravido-puerperal (12 cases), medical disorders (15 cases), post-traumatic (2 cases). Dosage was 150 U/kg every 18 hours subcutaneously. The usual symptomatic treatment included: transfusion of red cells, frozen fresh plasma, platelets and antithrombin III as necessary. A hemorrhage syndrome was present in 16 cases. The course of the disease was evaluated on clinical findings and surveillance of hemostasis parameters; anti-Xa activity was determined in 15 patients. RESULTS: Hemorrhage was arrested and biological values normalized in 22 patients (76%) including 15 (52%) survivors. In the 7 cases where the coagulopathy was not improved, the hemorrhagic syndrome persisted in 4. In the 22 successful outcomes, the hemostasis was corrected within 48 to 72 hours, with the exception of the thrombopenia, which persisted up to the 6th day. Mean anti-Xa activity was 0.32 +/- 0.16 anti-Xa U/ml. CONCLUSION: Results of this preliminary, non-randomized study show CY 222 to be as effective as heparin in the treatment of consumption coagulopathies.

Adult↗
PubMed1986

Structural genes of coagulation factors VII and X located on 13q34.

From 7 cases of abnormalities involving chromosome 13, the structural gene(s) coding for coagulation factors VII and X were located in the region 13q34-13qter. Gene-dosage effects for these coagulation factors seem to act in both directions, causing a decrease when there is monosomy of segment 13q34, but also, as has not been demonstrated before, an increase when there is trisomy of this same segment.

Adolescent↗
PubMed1985

[Prevalence of anti-LAV antibodies in hemophiliacs, correlation with the immunological state].

49 french haemophiliacs (haemophilia A: 41 patients; haemophilia B: 8 patients) were serologicaly tested for LAV antibodies: 10 patients (20.4%) were seropositive including 9 (21.9%) with haemophilia A and 1 (12,5%) with haemophilia B. Between seronegative and seropositive patients total lymphocyte and T-lymphocyte sub-populations counts were not significantly different. The mean serum IgG level was higher and palpable lymphadenopathy more frequently encountered among seropositive patients.

Antibodies, Viral↗
PubMed1985

Prevalence of antibodies to lymphadenopathy-AIDS virus in French haemophiliacs.

49 French haemophiliacs (haemophilia A: 41 patients; haemophilia B: 8 patients) were serologically testes for lymphadenopathy-AIDS virus antibodies: 10 patients (20.4%) were seropositive including 9 (21.9%) with haemophilia A and 1 (12.5%) with haemophilia B. Among haemophiliacs A, seropositive patients received significantly larger amounts of factor VIII concentrate during the 2 years preceding the study.

Adult↗
PubMed1985

[Immunological status of hemophiliacs: study of blood T-lymphocyte populations, serum immunoglobulins, and the prevalence of anti-LAV antibodies].

Blood T-lymphocyte subsets and serum immunoglobulin levels were studied in a group of 52 haemophiliacs (44 patients with haemophilia A and 8 patients with haemophilia B). None of the patients had AIDS or belonged to any AIDS high-risk group. Patients were exclusively treated with clotting fractions obtained from healthy volunteers in metropolitan France. As compared to a group of 52 normal donors, haemophiliacs had increased numbers of suppressor lymphocytes, which resulted in depressed helper/suppressor (H/S) ratios, and increased levels of serum IgG and IgA. 21 haemophiliacs (40,3%) had a H/S ratio less than 1.4. Among patients with haemophilia A a higher mean IgG level was found in patients presenting lymphadenopathy. Decreased mean H/S ratio and increased mean serum IgG level were found in patients receiving more than 50 000 U of factor VIII during the 2 years preceding the study. No striking difference in mean serum IgG, IgA and IgM levels was found in patients with haemophilia A when H/S ratios were higher and lower than 1.4 respectively. As AIDS and immunological abnormalities among haemophiliacs probably share a common viral origin, this study emphasize the need to discourage blood donation from donors who belong to any AIDS high-risk group, and to screen sera from the blood donor population for antibodies to LAV/HTLV III.

Acquired Immunodeficiency Syndrome↗
PubMed1984

[Blood T lymphocyte populations in the hemophiliac].

We have studied a group of 31 hemophiliac patients (hemophilia A: 26 patients, hemophilia B: 5 patients); 29 healthy men were used as controls. Hemophiliac patients had increased percentages of suppressor T-lymphocytes and depressed T4/T8 ratios. These abnormalities were found to be significantly correlated with the amount of F VIII used per year.

Adolescent↗