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Biomedical subjects

D Bachir

Publications and source records attributed to D Bachir.

At least 55 records · Page 3Linked to original sources
PubMed1993

Frozen blood and transfusion-transmitted hepatitis C virus.

The purpose of the present study was to evaluate the impact of frozen red cell transfusion on the transmission of hepatitis C virus (HCV) before the introduction of blood donor screening. Anti-HCV antibodies were detected in 59 patients with sickle-cell disease who required chronic transfusions and had exclusively received frozen red blood cells (RBC). The files were reviewed for clinical signs of chronic hepatitis C. Anti-HCV antibodies were detected in 2 adult patients; both also had clinical evidence of HCV infection. No other patient showed signs of acute or chronic HCV hepatitis. In a control group of 28 patients who had received nonfrozen RBC transfusions, the prevalence of anti-HCV antibodies was 25%. So, our study seems to indicate that the use of frozen RBC had reduced the risk of HCV contamination.

Adolescent↗
PubMed1993

Increased in vivo production of thromboxane in patients with sickle cell disease is accompanied by an impairment of platelet functions to the thromboxane A2 agonist U46619.

Thrombosis represents an important cause of mortality in patients with sickle cell disease, in addition to the complications caused by the primary defect of inherited abnormal hemoglobin. To study the involvement of platelets in these complications, we assessed the biosynthesis of thromboxane A2 in samples from 49 patients with sickle cell disease and in 33 control subjects. The urinary excretion of the major arachidonic acid metabolite of platelet origin (11-dehydro-thromboxane B2) and of the vascular endothelial cell (2,3-dinor-6-ketoprostaglandin F1 alpha) were very significantly increased (p < 0.0002) in the patients. In a small group of patients (n = 14), we further investigated the ex vivo response of their platelets to U46619, a stable analogue of thromboxane A2. We observed decreased aggregation and [14C]serotonin release compared with control (p < 0.05); similarly, we found impaired p47 protein phosphorylation (p < 0.05). In contrast, platelets from these patients responded normally to thrombin (0.1 unit/mL). In vivo desensitization of platelets from these patients to thromboxane may constitute a form of regulation that may prevent the propagation of aggregation by this potent inducer, as has been hypothesized in in vitro studies. Our results may also provide a rationale for using antiplatelet drugs in the prophylaxis of thrombotic complications in sickle cell patients.

6-Ketoprostaglandin F1 alpha↗
PubMed1993

Avascular necrosis of the femoral head in sickle-cell disease. Treatment of collapse by the injection of acrylic cement.

In ten patients with sickle-cell disease, we used a new technique of cement injection for the treatment of 16 painful hips with a radiographic crescent line or flattening of the articular surface due to avascular necrosis. The necrotic bone and overlying cartilage are elevated by the injection to restore the sphericity of the femoral head. Five days after the operation, full weight-bearing was allowed with the help of crutches for three weeks. The time in hospital averaged eight days; the average blood loss was 100 ml. There was early pain relief and postoperative radiographs showed improvement in the shape of the femoral head. At a mean follow-up of 5 years (3 to 7), 14 of the 16 hips were still improved although some gave slight pain. Only two hips had required revision to total hip arthroplasty, at one year and two years respectively. The increasing longevity of patients with sickle-cell disease means that avascular necrosis will be an increasing problem. Total hip replacement has a poor prognosis because of the risks of infection, high blood loss, and early loosening. Cement injection does not have these problems and allows for earlier, more conservative surgery.

Adult↗
PubMed1992

[Management of drepanocytic patients].

Comprehensive supportive care includes outpatient follow up (periodic evaluation of baseline status, psychosocial support, prevention of sepsis through oral prophylactic penicillin in young children and vaccinations, early treatment of acute episodes (painful crises, other vaso-occlusive events, infection, acute anemia...); In adulthood residual organ dysfunction becomes one of the foremost problems. Further, more specific high risk situations (pregnancy, anesthesia) require adequate responses. Early diagnosis, improved strategy of care best achieved in Sickle Cell Centers can reduce mortality and morbidity in the aim of providing a better quality of life.

Acute Disease↗
PubMed1992

Hemoglobin variants and activity of the (K+Cl-) cotransport system in human erythrocytes.

To determine if the activation of the (K+Cl-) cotransport system observed in hemoglobin (Hb) S- or C-containing erythrocytes is related either to a global change of isoelectric point of the Hb molecule or to the specific location of these mutations on the position 6 of the beta chain of Hb, we studied the (K+Cl-) cotransport system in erythrocytes containing beta chain variants exhibiting either the Glu----Lys substitution observed in position beta 6 in Hb C (Hb E: beta 26 Glu----Lys; Hb O-Arab: beta 121 Glu----Lys; Hb Siriraj:beta 7 Glu----Lys) or the Glu----neutral residue substitution observed in position beta 6 in Hb S (Hb G-San Jose: beta 7 Glu----Gly; Hb D Punjab or D-Los Angeles: beta 121 Glu----Gln). The K transport mediated by the (K+Cl-) cotransport was increased in AC, AS and A-Siriraj and A-San Jose red blood cells and was similar to AA control in the other variants. These results indicate that an enhanced (K+Cl-) cotransport is not a property of all positively charged Hb variants, but it is mainly associated with mutations occurring at the beta 6 or beta 7 residues. An interaction of Hb with the cell membrane mediated by the disappearance of one of the negative charged residues (Glu) at this site of the A helix of the beta chain is the most likely candidate for the persistent activation of the (K+Cl-) cotransport system in these Hb variants.

Biological Transport↗
PubMed1992

Severe pneumococcal sepsis and meningitis in human immunodeficiency virus-infected adults with sickle cell disease.

Pneumococcal infection is frequent in children with sickle-cell disease (SCD) but is less common in adults. Infection due to human immunodeficiency virus (HIV) is also a risk factor for pneumococcal infection. The purpose of this study was to determine the clinical course of HIV infection in adults with SCD. During a 6-year period, 283 adults suffering from SCD were screened for HIV type 1 and HIV type 2 infections. The clinical course of HIV infections in these patients was retrospectively analyzed at the term of the study. HIV type 1 infection was detected in eight patients. The mean follow-up period after diagnosis of HIV infection was 4.6 years. None of the patients had AIDS. Five episodes of severe pneumococcal infection were observed in four of these eight patients (septic shock in two patients and three episodes of meningitis in two patients); two patients died of meningitis. Only one severe pneumococcal infection (meningitis) was observed in the 275 non-HIV-infected patients with SCD (P = .000001). Our results show that pneumococcal infection appears to occur frequently and is often serious in HIV-infected adults with SCD.

Adult↗
PubMed1991

K+ efflux in deoxygenated sickle cells in the presence or absence of DIOA, a specific inhibitor of the [K+, Cl-] cotransport system.

The ouabain bumetanide resistant (OBR) K+ efflux was investigated in deoxygenated sickle cells in comparison to oxygenated ones, by using a specific inhibitor of the [K+, Cl-] co-transport system, [(DihydroIndenyl)Oxy] Alkanoic acid (DIOA). A DIOA sensitive and a DIOA resistant K+ efflux were measured in deoxygenated sickle cells. The DIOA sensitive K+ efflux shared the properties of the [K+, Cl-] co-transport system, being stimulated by decreased pH and hypoosmolarity. This DIOA sensitive K+ efflux represented 70% of the total K+ efflux at pH 7.0 and at low pO2 (10-15 mmHg). Thus, a small reduction in Ph effectively stimulated the [K+, Cl-] co-transport system in deoxygenated condition, and this may contribute significantly to the sickle cell dehydration. We conclude that at pH lower than 7.4, the [K+, Cl-] co-transport system is permanently activated in sickle cells and leads to sickle cell dehydration in both oxygenated and deoxygenated conditions.

Adult↗
PubMed1991

Deformities of the hip in adults who have sickle-cell disease and had avascular necrosis in childhood. A natural history of fifty-two patients.

We report the natural course of the hip in fifty-two patients (ninety-five hips) who had sickle-cell disease and had had avascular necrosis in childhood. There were twenty-one African, twenty-one West Indian, and ten Mediterranean patients. At the most recent follow-up examination (at an average duration of nineteen years after the onset of the disease), 80 per cent of the hips that had been affected by avascular necrosis during childhood were painful and had permanent damage with regard to decreased mobility, limb-length discrepancy, and an abnormal gait. When the patients were evaluated, at an average age of thirty-one years, fifteen hips (16 per cent) had had an operation for progressive disability and sixty (63 per cent) had major problems because of pain. Of the twenty hips (21 per cent) that were not painful, five were in patients who had an abnormal gait, with decreased agility. The mean Iowa hip-rating score at the most recent follow-up examination was 73 points (range, 30 to 100 points). Correlations were found between the hip score and the patient's age at the onset of the disease and at the latest follow-up, between the hip score and degenerative changes in the hip, and between degenerative changes and radiographic evidence of deformity of the hip.

Adult↗
PubMed1990

[Transfusion in sickle cell anemia].

Transfusion is one of the fundamental treatments in complications of sickle cell anaemia, a disease with peculiar features requiring an appropriate transfusion policy. Owing to the higher risk of vascular occlusion it carries, simple blood transfusion is indicated only for acute anaemia and for the very rare long-term transfusion programmes. In patients with severe occlusive and/or septic accidents, the risk of decompensation makes it mandatory to promptly reduce the sickle cell concentration; this is achieved by exchange transfusion the modalities of which are described by the authors. General anaesthesia also requires exchange transfusion in volumes that depend on the risk incurred. Finally, some patients benefit from a long-term transfusion programme. Potentially repeatable transfusions imply the use of phenotypes and leucocyte-freed red cell concentrates as well as detection and prevention of viral infections transmitted by transfusion. This article summarizes the recommendations that can now be made concerning the use of perfusion in the management of sickle cell anaemia.

Anemia, Sickle Cell↗
PubMed1990

Fate of alpha-hemoglobin chains and erythrocyte defects in beta-thalassemia.

The fate of alpha-hemoglobin chains and the cause of membrane protein defects in thalassemic erythrocytes have been studied in: (1) human beta-thalassemia syndromes, (2) mouse beta-thalassemia, and (3) normal human erythrocytes loaded with purified alpha-hemoglobin chains. The similarity and differences observed in these three systems underline the importance of insoluble alpha chains and the direct relationship between the amount of these chains and the membrane protein defects. Indeed, in addition to the alpha/non-alpha ratio of globin chain synthesis, the proteolysis and instability of alpha chains are major factors in modulating the cellular defects.

Animals↗
PubMed1990

Congenital sideroblastic anemia without clinical iron overload. A case report.

An 18 year old boy presented with microcytic hypochromic anemia. Erythrocytic abnormalities and family studies suggested congenital sideroblastic anemia (CSA), but atypical features included absence of clinical iron overload, scanty iron deposits in mitochondria of late erythroblasts and reticulocytes, and a high platelet count. An unusual adhesion between bone marrow macrophages and reticulocytes was observed by electron microscopy. Haematological response was seen following pyridoxine administration, thus fending support to the diagnosis of CSA.

Adolescent↗
PubMed1989

A study of membrane protein defects and alpha hemoglobin chains of red blood cells in human beta thalassemia.

The soluble pool of alpha hemoglobin chains present in blood or bone marrow cells was measured with a new affinity method using a specific probe, beta A hemoglobin chain labeled with [3H]N-ethylmaleimide. This pool of soluble alpha chains was 0.067 +/- 0.017% of hemoglobin in blood of normal adult, 0.11 +/- 0.03% in heterozygous beta thalassemia and ranged from 0.26 to 1.30% in homozygous beta thalassemia intermedia. This elevated pool of soluble alpha chains observed in human beta thalassemia intermedia decreased 33-fold from a value of 10% of total hemoglobin in bone marrow cells to 0.3% in the most dense red blood cells. The amount of insoluble alpha chains was measured by using the polyacrylamide gel electrophoresis in urea and Triton X-100. In beta thalassemia intermedia the amount of insoluble alpha chains was correlated with the decreased spectrin content of red cell membrane and was associated with a decrease in ankyrin and with other abnormalities of the electrophoretic pattern of membrane proteins. The loss and topology of the reactive thiol groups of membrane proteins was determined by using [3H]N-ethylmaleimide added to membrane ghosts prior to urea and Triton X-100 electrophoresis. Spectrin and ankyrin were the major proteins with the most important decrease of thiol groups.

Erythrocyte Membrane↗
PubMed1989

[Natural history of hip necrosis in sickle cell disease. Apropos of 104 necroses].

The authors have followed 140 patients with sickle cell disease anemia (101 cases) or related hemoglobinopathies (39 cases). Among them hip involvement was noted in 55 (104 hips). Forty three times the hip involvement occurred in childhood and twelve times in adult life. When the necrosis appeared in childhood (84 hips) the average age was twelve. The deformity involved the femoral head (coxa plana, coxa magna) as well as the neck (short neck, coxa vara). After an average follow-up of nineteen years, clinical and radiological examinations evidenced 64 functional impairments and 25 arthrosis, 10 of which have already been operated on. The necrosis appearing during adult life (20 hips) had the same outcome as idiopathic necroses, leading rapidly to arthrosis after collapse of the sequestrum. It seems that the etiology of the necroses is linked to rheologic disorders, the deformity of the red cells causing arteriolar thromboses. In this series the hip disease was correlated with sickle cell retinopathy as defined after angiography. On the contrary there was no correlation with the severity of anemia, its treatment, the ethnical origin of the patient.

Adolescent↗
PubMed1987

Gerbich reactivity in 4.1 (-) hereditary elliptocytosis and protein 4.1 level in blood group Gerbich deficiency.

The membrane polypeptide composition and the blood group Gerbich phenotype of red cells from 4.1 (-) hereditary elliptocytic patients and from Gerbich-negative donors, who display two unrelated genetic abnormalities, were compared. In homozygous 4.1 (-) hereditary elliptocytosis where the primary defect was presumably the absence of the membrane skeletal protein 4.1, there was approximatively a 70% reduction in the minor sialoglycoproteins beta and gamma. This was associated with a severe reduction of blood group Gerbich reactivity as determined with both murine monoclonal and human anti-Gerbich antibodies. In the heterozygous state in the presence of one haploid set of protein 4.1 gene there was only a modest decrease in glycoproteins beta and gamma and the Gerbich serological reactivity was within normal limits. In homozygous Gerbich-negative red cells which lack glycoproteins beta and gamma but do not display elliptocytic red cells, the levels of protein 4.1 was repeatedly found within or just below the lowest values of normal controls. In the heterozygous Gerbich-negative conditions, glycoproteins beta and gamma were present in reduced amounts but the blood group Gerbich reactivity fell within normal limits since the anti-Gerbich reagents used were unable to detect a dosage effect. The amount of protein 4.1 was normal. These results add further support to the view that protein 4.1 and the sialoglycoproteins beta and gamma are physically linked in vivo which in some way serve to maintain red cell shape and integrity. Of interest was the finding that absence of protein 4.1 had a greater influence on the level of membrane glycoproteins beta and gamma than did the absence of beta and gamma glycoproteins on band 4.1.

Blood Group Antigens↗