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Biomedical subjects

P Gaussem

Publications and source records attributed to P Gaussem.

51 records · Page 3Linked to original sources
PubMedDate not supplied

[Myelodysplastic syndromes].

Myelodysplastic syndromes (MDS) are clonal disorders of pluripotent hematopoietic stem cells. MDS occur predominantly over the age of 60 years. The diagnosis of MDS is based on the examination of both blood films and bone marrow aspirate. Diseases such as vitamin B12 and/or folate deficiency, or cytotoxic therapy leading to a marrow dysplasia should be ruled out. Five subtypes are described in the FAB classification : refractory anaemia or refractory cytopenia, refractory sideroblastic anaemia, refractory anaemia with excess of blasts, refractory anaemia with excess of blasts in transformation, chronic myelomonocytic leukaemia. This FAB classification is based on a small number of parameters: percentage of blood and marrow blasts, percentage of ringed sideroblasts and blood monocytes. The anaemia is typically normo- or macrocytic, non regenerative, and in half cases is associated with neutropenia and/or thrombocytopenia. During blood film examination, cell abnormalities have to be notified, i.e. anisocytosis, poikilocytosis of red cells, morphological abnormalities of neutrophils including hypogranulation, hypolobulation, abnormal large platelets. The prognostic and the treatment of MDS depend on the subtype of the FAB classification, the patient's age, the percentage of marrow blasts, the importance of cytopenia, the presence or not of cytogenetic abnormalities and the existence or not of HLA-identical donor.

Diagnosis, Differential↗
PubMedDate not supplied

[Myelodisplasic syndromes diagnosed in a geriatric hospital: morphological profile in 100 patients].

Myelodysplastic syndrome (MDS) is particularly common in geriatric practice. As few data are available in very elderly patients, we conducted a 54-month retrospective study in patients over 70 years with MDS diagnosed at Hôpital Charles Foix. Patients with cobalamine, folate or iron deficiency were excluded. Regarding biological and morphologic approaches, MDS patients were classified according to the FAB criteria. We then tempted to reclassify the patients according to the WHO criteria. The Bournemouth scoring system was used as a prognostic tool. During the study period, 100 patients were included, 29 males and 71 females, median age 86 +/- 7 years (70-103). At the time of bone marrow sampling, a peripheral blood cytopenia was documented in 64 patients, a bicytopenia in 27 patients and a pancytopenia in 9 patients. Isolated anaemia (Hb < 12 g/dL) was found in 60 patients and isolated thrombocytopenia (< 150 x 10(9)/L) in 4. Macrocytosis (MCV > 100 fL) was observed in 21 % of the cases. According to the FAB criteria, the 100 patients were classified as follows: refractory anaemia (RA): 79%; RA with ringed sideroblasts (RARS): 8%; RA with excess of blasts (RAEB): 8%; RAEB in transformation: 1%; chronic myelomonocytic leukaemia: 4%. According to the WHO classification, the patients were reclassified as follows: RA (unilineage) (with or without ringed sideroblasts): 10%; refractory cytopenia with multilineage dysplasia with or without ringed sideroblasts (RCMD): 73%; RAEB: 7% (RAEB-1 6%, RAEB-21%); MDS/Myeloproliferative disorder: 4%; unclassified (hypocellularity): 5%; acute leukaemia: 1%. In order to estimate prognosis at the time of the bone marrow aspirate, we calculated the Bournemouth'score: 8 patients scored 0,57 scored 1,25 scored 2,8 scored 3 and 2 scored 4. In this geriatric population, 83% cases of MDS are RA or RCMD (with or without sideroblasts); MDS with excess of blasts are uncommon. Thus, elderly patients under study with MDS were diagnosed at an earlier stage of the disease than younger ones from series published in the literature. Due to frequent comorbidities, geriatric patients may be symptomatic for a slight decrease of haemoglobin level. Therefore, elderly patients are investigated as soon as they present with moderate anaemia that may explain the early MDS diagnosis.

Aged↗
PubMedDate not supplied

[Role of platelet dysfunction in the haemostatic manifestations occurring during essential thrombocythaemia].

Among myeloproliferative disorders, Essential Thrombocythaemia is the most frequent and the one associated with the better prognosis. Although median survival is above 15 years, Essential Thrombocythaemia may be complicated by haemostatic life-threatening manifestations. Occurrence of thromboembolic or haemorrhagic episodes, even both in a same patient, are not predictable and physiopathology of Essential Thrombocythaemia remains misunderstood. Many studies have been conducted to explain the mechanisms responsible for the haemostatic complications and to determine predictive biological factors in order to improve the management of patients. We report here a review of the potential roles of platelets in Essential Thrombocythaemia through their interaction with coagulation and fibrinolysis systems as well as with cellular components (leukocytes and endothelium). Many controversial data have been published so far. However, a deficiency in high molecular multimers of von Willebrand factor is currently admitted, as well as deficiency of platelet membrane proteins and the presence of circulating activated platelets, especially in erythromelalgia. However, no biological abnormality has been correlated with the clinical manifestations. The haemostatic complications are likely to result from a multifactorial process in which accumulated moderated risk factors unbalance the procoagulant/anticoagulant pathways.

Blood Platelets↗
PubMedDate not supplied

[Prognostic factors in chronic lymphocytic leukaemia: contribution of recent biological markers].

Chronic lymphocytic leukemia (CLL) is the most common lymphoid hemopathy in elderly. Diagnosis of CLL is easily made with a full blood count and immunophenotyping, but there is an heterogeneity in clinical evolution. Until now, scheduling of treatment is based on Rai or Binet staging systems. These staging systems can not distinguish patients with a rapid evolution and thus who will need an earlier treatment. In order to detect these patients, it is useful to have some relevant markers to predict disease evolution. This article reviews recent biologic markers that can be used to evaluate long term prognosis of CLL patients.

Biomarkers, Tumor↗
PubMedDate not supplied

[Acquired mutation of JAK2 tyrosine kinase and polycythaemia vera].

Polycythaemia vera is an acquired myeloproliferative disorder characterised by a polycythaemia resulting of a clonal disorder arising in a multipotent hematopoietic stem cell. The increase of red cell mass exposes to a high risk of arterial or venous thrombosis and thus requires a cytoreductive treatment. An acquired genetic mutation in exon 12 of the JAK2 tyrosine kinase gene, leading to a substitution of a valine to a phenylalanine (V617F), has been described in most polycythaemia vera patients. This mutation increases the phosphorylation activity of JAK2, promotes the spontaneous cellular growth and induces erythrocytosis in a mouse model. Prevalence studies of V617F JAK2 mutation in different myeloproliferative disorders have found this genetic alteration in half of idiopathic myelofibrosis and in one third of essential thrombocythaemia. This finding is a huge progress in the understanding of polycythaemia vera physiopathology, it will be also an useful tool for the diagnosis of myeloproliferative disorders and it opens a new field for the development of targeted therapeutic approaches in these disorders.

Amino Acid Sequence↗
PubMedDate not supplied

[Physiologie and cellular regulation of the protein C system].

The protein C (PC) pathway is a major anticoagulant system, the role of which is evidenced by the incidence of thrombotic events occurring in patients presenting PC or PS deficiencies. However, the regulation mechanism of this system is not yet well understood. A part of the thrombin produced during the coagulation process interacts with the protein thrombomodulin on the endothelium surface. This thrombin-thrombomodulin complex converts PC to activated PC (APC). APC then interacts with its cofactor protein S on phospholipid surfaces, and proteolytically inactivates factors Va and VIIIa, thus limiting the thrombin formation. Factor V mutation at position 506 (replacement of an Arg by a Gln) results in a decrease of factor Va inactivation rate by APC and has been recently described as a thrombosis risk factor. This "APC resistance" has been found in 15 to 20% of patients with antecedents of thromboembolic events. The PC pathway is also linked to the inflammatory reaction. A fraction of circulating PS is complexed to a regulatory protein of the complement system, the C4b binding protein (C4bBP) and only the free PS is active. An increase in the C4bBP level results in an elevation of bound PS, and as a consequence in a decrease of the free active form of PS. Moreover, endotoxins and cytokins inhibit the expression of both TM and the recently described PC cellular receptor. Under these conditions, a stimulation of tissue factor expression occurs on activated monocytes and endothelials cells surface. APC also modulates inflammatory response, through preventing tumor necrosis factor production. Thus, in the absence of PC, inflammation leads to an increased thrombin formation. This suggests that functions of PC system components are not only implicated in the regulation of the coagulation process, but also in inflammatory reactions and cellular proliferative responses.

Blood Coagulation↗
PubMedDate not supplied

[Evaluation of hemostasis in venous thromboembolism pathology].

Thromboembolic disease results from an hypercoagulable state and multifactorial causes may lead to hypercoagulability. Thrombogenic risk factors can be acquired and/or inherited. For each thrombophilic patient, the main clinical features retained are: the patient age, the familial history, the recurrence of thromboembolic events, an unusual site of thrombosis. Anti-phospholipid antibodies, which are considered as acquired thrombogenic risk factors, can be detected with coagulation tests and/or Elisa methods. The association of antiphospholipid antibodies with thrombosis is defined as the anti-phospholipid syndrome. Last decades, genetic risk factors were identified. First of all, antithrombin, protein C and protein S deficiencies were described. These deficiencies are involved in about 10% of patients who develop thrombosis before the age of 50. In 1993, a new genetic risk factor was discovered: activated protein C resistance which is due to the Q506 mutation in factor V. This defect represents the most prevalent abnormality of inherited thrombophilia, affecting 20 to 40% of thrombophilic patients. Interestingly, hyperhomocysteinemia, known as potentially predisposing to arterial disease, was also recognized as a risk factor for venous occlusive disease. Several genes encoding homocystein metabolism enzymes, such as cystathionine beta-synthase or methylenetetrahydrofolate reductase are concerned. Establishment of a causal association between the presence of a biological abnormality and the occurrence of thrombosis may lead to an adapted prophylaxis whatever the risk situation.

Antiphospholipid Syndrome↗