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Biomedical subjects

B Varet

Publications and source records attributed to B Varet.

At least 109 records · Page 6Linked to original sources
PubMed1988

Etiology of portal vein thrombosis in adults. A prospective evaluation of primary myeloproliferative disorders.

In a prospective study of 33 adults with portal vein thrombosis unrelated to a liver tumor, we have assessed the prevalence of primary myeloproliferative disorders using conventional criteria and cultures of bone marrow progenitor cells. A primary myeloproliferative disorder was documented in 14 patients investigated at the time of recognition of portal vein thrombosis. Among these 14 patients, the main clue to the presence of the myeloproliferative disorder was (a) the observation of suggestive abnormalities of peripheral blood cell counts in 4 patients; (b) characteristic findings at bone marrow biopsy or determination of total red cell volume in 3 patients; and (c) formation of "spontaneous" erythroid colonies in cultures of bone marrow progenitor cells in erythropoietin-poor medium in 7 patients. In 2 other patients, agnogenic myeloid metaplasia with myelosclerosis of apparently recent onset developed 5 yr after recognition of portal vein thrombosis. In conclusion, primary myeloproliferative disorders--in a full-blown or latent form, or at an early stage--are a major cause of portal vein thrombosis.

Blood Cell Count↗
PubMed1988

Peripheral antiglucocorticoid action of RU 486 in man.

In order to evaluate the peripheral antiglucocorticoid activity of RU 486 in man we examined its ability to antagonize the effects of acutely administered glucocorticoids on blood leukocyte counts. The study was performed on eight normal male subjects. They were given 400 mg RU 486 (or placebo) orally at 0730 h and 1 mg dexamethasone (or placebo) orally at 0830 h, using a double-blind, cross-over, latin-square design with a one week interval between each of the four different treatments. Circulating eosinophils, lymphocytes, and neutrophils were counted at 0730 h and 1330 h, and their variations (1330 h counts/0730 h counts x 100) were compared under each treatment. For each cell type, dexamethasone induced variations (eosinophil and lymphocyte drop, neutrophil rise) which were significantly (P less than 0.05) different from those under the three other treatments; these latter treatments (placebo, RU 486, and RU 486 + dexamethasone) were equivalent to each other, inducing no variations of leucocyte counts. These data show that RU 486 inhibits dexamethasone induced leukocyte changes; this simple test provides a useful means to further analyse the peripheral antiglucocorticoid activity of RU 486 in man.

Adult↗
PubMed1988

Peritubular cells are the site of erythropoietin synthesis in the murine hypoxic kidney.

Erythropoietin (Epo)-producing cells were identified in the murine hypoxic kidney by in situ hybridization. Profound anemia was induced in order to greatly increase Epo production. This resulted in high levels of Epo mRNA in the kidney. 35S-labeled DNA fragments of the murine Epo gene were used as probes for in situ hybridization. Control experiments conducted in parallel included kidneys of nonanemic mice, RNase-treated hypoxic kidney sections, and 35S-labeled non-Epo-related DNA. The Epo probe gave a specific hybridization signal in the hypoxic kidney in the cortex and to a lesser extent in the outer medulla. Glomerular and tubular cells were not labeled. All positive cells were identified as peritubular cells. Using immunofluorescence, we showed that cells with the same topography contained Factor VIII-related antigen. These data demonstrated that peritubular cells, most likely endothelial cells, constitute the major site of Epo production in the murine hypoxic kidney.

Animals↗
PubMed1988

Castleman's disease of the leptomeninges. Report of three cases.

Castleman's disease is a rare, benign lymphoproliferative disorder that usually arises in lymph nodes, most commonly in the mediastinum. The authors report the clinical and pathological features of three patients with localized Castleman's disease of the leptomeninges. There were two women, aged 63 and 82 years, and one 25-year-old man. Two patients had progressive focal motor seizures of 3 and 24 months' duration, and the third patient presented acutely with generalized seizures. The clinical diagnosis was meningioma in each case, based on computerized tomography scans, cerebral arteriography, and the operative findings. All three lesions arose in the leptomeninges, compressed the underlying cerebral cortex, and infiltrated the overlying dura to a variable extent. Surgical excision of the tumor resulted in marked clinical improvement in all three patients. Histologically, two cases were classified as the hyaline-vascular type and one as the plasma cell type. Immunohistochemical stains of the latter case revealed a monoclonal population of mature plasma cells. Only a few scattered polyclonal plasma cells were seen in the other two cases. The authors conclude that Castleman's disease involving the leptomeninges is a rare disorder that may mimic meningioma clinically and radiographically.

Adult↗
PubMed1988

[A study of hematology questions on the competitive examination of medical residents 1984, 1985 and 1986].

The recently (1984) introduced new modalities for selecting the residents in France is based upon multiple choice (MCQ) questions (2/3) and written answers to patients managements problems (PMP) (1/3). MCQ and PMP are selected by a group for 8 hematologists from the 42 French schools of medicine. The process of selecting the questions, the major topics explored by these questions, the docimological quality of the questions and the most surprising errors made by the candidates are studied. Results argue for a sustained effort in order to improve the teaching of the basis of hematology in our country.

Educational Measurement↗
PubMed1987

Biochemical analyses of murine erythropoietin from plasma and from cloned erythroleukemia cells.

The hydrophobicity, ionic charges, degrees of glycosylation, and Western blot patterns of murine plasma erythropoietin and erythropoietin produced by clones of two murine erythroleukemic cell lines (IW32 and NN10) were compared. Erythropoietins from these different sources exhibited a number of similarities in their biochemical properties: identical retention on DEAE Affigel blue column and similar apparent molecular weights (30-36 kDa) in Western blot analysis. However, differences were also observed: heterogeneous binding to different lectin columns and varied retention on a phenyl Sepharose column. The data thus confirm that these murine plasma erythropoietins have biochemical properties in common with previously studied erythropoietins from humans or sheep. The major difference between erythropoietins secreted by erythroleukemic cell lines and other molecules belonging to the same family appears to be related to their glycosylation.

Animals↗
PubMed1986

In vitro myotrophic effect of serum kappa chain immunoglobulins from a patient with kappa light chain myeloma and muscular hypertrophy.

Muscle hypertrophy due to enlarged muscle fibers was accompanied by kappa light chain myeloma in a 62-yr-old man. Immunofluorescence showed kappa light chain deposits around muscle fibers. We hypothesized that a circulating growth factor may be involved in the pathogeny of this muscular hypertrophy. Patient serum cultured with muscle cells showed that (a) the patient's serum exhibited a trophic effect on human muscle cells in culture, (b) this trophic effect increased the differentiation and did not influence the proliferation of human muscle cells, and (c) the fraction of the patient's serum immunoadsorbed on antihuman kappa chain antibodies exhibited the same in vitro effect on the muscle cells, whereas the fraction immunoadsorbed on antihuman lambda chain antibodies did not. These results support the hypothesis that the patient's kappa light chains have a specific enhancing effect on human muscle cell differentiation, perhaps leading to an acquired muscular hypertrophy.

Cell Differentiation↗
PubMed1986

[Association of autoimmune chronic active hepatitis and acquired erythroblastopenia cured by cyclophosphamide].

To the best of our knowledge this is the reported first case of the successive occurrence in the same patient of chronic active hepatitis and acquired pure red cell aplasia, both probably of autoimmune origin. The diagnosis of autoimmune hepatitis was based on the presence of characteristic lesions at the examination of the liver biopsy specimen, high titer of anti-smooth muscle antibodies in the serum, and remission obtained by steroid therapy. Erythroid aplasia, which appeared during the course of this treatment, was revealed by a regenerative anemia (4.4 g Hb/100 ml) and proved by bone marrow aspiration and biopsy. In vitro bone marrow culture was normal, suggesting the in vivo presence of an inhibitor of erythroblastic differentiation. Red cell aplasia was cured by cyclophosphamide (100 mg/day during 56 days). No recurrence was noted until the death of the patient, which occurred one year later, due to hepatic cholangiocarcinoma. Action of cyclophosphamide on the pure red cell aplasia suggested the immune origin of this disease. The liver and the bone marrow erythroid lineage have probably been the successive targets of immunologic dyscrasia.

Autoimmune Diseases↗
PubMed1985

Chorea and polycythaemia.

Two patients with chorea and polycythaemia vera are described. The literature on this rare association is reviewed and its pathophysiology discussed.

Aged↗
PubMed1985

Primary myeloproliferative disorder and hepatic vein thrombosis. A prospective study of erythroid colony formation in vitro in 20 patients with Budd-Chiari syndrome.

We assessed the prevalence of overt and latent primary myeloproliferative disorders in hepatic vein thrombosis. Cultures of bone marrow or peripheral blood mononuclear cells were done in 20 patients with Budd-Chiari syndrome. Erythroid colony formation in the absence of erythropoietin, which is a reliable indicator for a primary myeloproliferative disorder, was seen in 16 patients in whom Budd-Chiari syndrome was due to hepatic vein thrombosis, including 13 women aged 18 to 45 years. Among these 16 patients, the conventional criteria for the diagnosis of a primary myeloproliferative disorder were met in only 2. Primary myeloproliferative disorder, often without peripheral blood changes, is a major cause of hepatic vein thrombosis in young women.

Adolescent↗
PubMed1985

Production of erythropoietin by cloned malignant murine erythroid cells.

A specific immunological assay was used to demonstrate that the erythropoietic factor produced by the recently described FMuLV-induced murine erythroleukemic cell line IW32 is an authentic erythropoietin (epo). Several independent virus-induced erythroleukemic and myeloblastic cell lines were tested for epo production. Among six erythroleukemic cell lines induced by FMuLV, another (NN10) was shown to produce epo by biological and immunological assays. Four Friend-virus-induced erythroleukemias and four FMuLV-induced myeloblastic cells were negative. The amounts of epo produced were similar in IW32 and NN10 supernatants after 48 h in culture. The in vitro bioassay gave the highest levels (up to 1000 mU/ml), the in vivo bioassay the lowest, and the radioimmunoassay gave intermediate results. NN10 and IW32 cell lines have been induced by two different FMuLV and were shown to be independent by cytogenetic studies. The molecular weights of IW32 and NN10 epo were close to the molecular weight of mouse plasma epo but elution profiles suggested that some differences might exist between these epos. Cloned IW32 and NN10 cells were shown to retain both the ability for erythroid differentiation after incubation with chemical inducers and the ability to produce epo. This demonstrates that malignant erythroid cells were the source of epo production in these cell lines.

Animals↗
PubMed1985

[Chronic lymphocytic leukemia, erythroblastopenia, thymolipoma].

The association of B cell chronic lymphocytic leukemia and pure red cell aplasia in a 42 year-old patient led to the discovery of a thymic enlargement. After six weeks treatment including steroids, cyclophosphamide and three courses of plasma exchange without improvement, surgical thymectomy was followed by a reticulocytosis and remission of the red cell aplasia. The tumor was a thymolipoma. Characteristics of this are thymic tumor, his connections with pure red cell aplasia and in vitro differentiation of erythroid progenitors are discussed.

Adult↗
PubMed1985

[Effect of the serum of a patient affected by myeloma with diffuse muscular hypertrophy on the growth of human muscle cells in vitro].

Diffuse skeletal muscle enlargement appeared in a 62 years old male without any detectable endocrine disturbance. The patient's weakness contrasted with his athletic appearance. There was no myotonia nor fasciculations. The laboratory investigations were unrevealing until 18 months after the apparent beginning of the disease: free kappa light chains in serum and urine and plasmocytosis in the bone marrow established the diagnosis of multiple myeloma. No amyloid infiltration was observed on the biopsied tissues: skin, muscle and tongue. The diameters of the muscle fibers were at the upper limit of the normal range. There was no fiber type grouping. Kappa light chain deposits surrounding the muscle fibers and numerous coated vesicles beneath the sarcolemmal membrane were found by electron microscopy. The patient's serum was tested on human muscle cell cultures and displayed trophic properties for these cells. This effect was not due to an acceleration of the myoblast proliferation, but to an enhancement of their differentiation. The fusion was more rapid than in presence of control serum and lead to larger and highly branched myotubes. Protein synthesis was increased as demonstrated by the significantly higher 3H-leucine incorporation into the trichloroacetic-acid precipitable material. An identical trophic effect was also found with the kappa light chains purified from the patient's serum but only in the presence of normal human serum.

Blood↗
PubMed1984

Structure and function of Hb Saint-Jacques (alpha 2 beta 2 140 (H18) Ala----Thr): a new high-oxygen-affinity variant with altered bisphosphoglycerate binding.

A low P50 value in a fresh red blood cell suspension was discovered in a polycythemic patient (Hb 19 g X dl-1). Routine acid and alkaline electrophoreses of the hemolysate were identical to normal hemolysate. Isoelectrofocusing (pH gradient 6-8) did not reveal any abnormal band whether performed with the fully liganded or deoxygenated samples. Precise analyses of the oxygen dissociation curves of the propositus' red cells demonstrated a biphasic Hill plot, a normal Bohr effect and low interaction with 2,3-bisphosphoglycerate (2,3-DPG). Studies on the unfractionated hemolysate confirmed these observations and the inhibition of the effect of organic phosphates. Structural studies were carried out on the mixture of beta A + beta X chains and revealed the presence of two beta Tp14 peptides. Sequencing the abnormal beta Tp14 peptide showed the substitution Ala----Thr of the beta 140 (H18) residue. This new variant was named Hb Saint-Jacques. Examination of the three dimensional model of HbAo indicates that the substitution beta 140 (H18) Ala----Thr induces van der Waals interactions with the nearby lysine-82 (EF6) and leucine-81 (EF5) and a displacement of the EF corner of the beta chains. This is likely to change the normal position of the lysine-82 (EF6), a major anionic binding site in the central cavity between the two beta chains. Functional studies confirm the interpretation of a steric hindrance inhibiting the binding of large organic phosphates to Hb Saint-Jacques.

2,3-Diphosphoglycerate↗