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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Acute myeloblastic leukemia, like certain other hematologic disorders, originates in pluripotent stem cells. Two general biologic processes underlie development of the disease. Over long times, clonal progression leads from normal polyclonal hemopoiesis through clonal preleukemia to leukemia. Overt leukemia is characterized by the emergence of blast cell populations. Over shorter times, clonal expansion yields cellular diversity based upon randomizing events. The analysis indicates that that blast population is of crucial importance. Characteristics of a colony assay for blast cell progenitors are presented.
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PMID:Acute myeloblastic leukemia considered as a clonal hemopathy. 29 69

Cytochemical investigations are useful for the characterization of different kinds of macrocytic anemias. Vitamin B12 and folate defects or chronic alcoholic myelopathy, induce in the erythroblasts cytochemical patterns which can be distinguished from those seen in preleukemia, erythroleukemia, or in drug induced toxic anemia. Tests for alpha-naphthol-acetate-esterase, for acid phosphatase, for iron, and for polysaccharides (PAS-stain), are especially valuable for these diagnostic procedures.
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PMID:[Cytochemical aspects in bone marrow cells in macrocytic anemias]. 29 38

We have compared the efficacy of computed tomography (CT) and air ventriculography (VGM) in the diagnostic evaluation of progressive nontumoral infant hydrocephalus where both examinations have been done without significant interventing time or treatment in infants under 12 months of age. CT alone was judged to be adequate for diagnosis and treatment 21 of 30 cases reviewed, provided that cerebrospinal fluid studies were available to complete diagnosis where necessary, and provided that the question of ventriculocisternal communication was not a factor in treatment selection. The ability to visualize cerebran aqueduct and 4th ventricle on CT was not always a reliable indicator of ventriculocisternal communication. CT was most adequate as the sole radiographic study in cases of myelodysplasia with Arnold-Chiari malformation, and in premature infants with intraventricular hemorrhage.
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PMID:A comparison of computed tomography and air ventriculography in diagnosis of progressive hydrocephalus of infancy. 31 16

Three very similar cases of sideroblastic idiopathic anemia were respectively observed for 105, 57 and 69 months. The cytogenetic blood study was normal. But the medullary genetic findings showed marker extra-chromosome, having the same aspect in each metaphase = 47 Mar +. It was respectively found in 13 mitoses/32, 2/45 and 1/30. The study of chromosome showed that it was not a normal cytogenetic C-chromosome at all, even it seemed to be a C - X type chromosome at first. The long arms had about the same size as the one of the C- type. But the short arms were really shorter. The study on R- bands showed a chromosomic marking unkown so far. The cytogenetic abnormalities described during the sideroblastic idiopathic anemias, the rare sideroblastic idiopathic anemias where were found a C- type chromosome really identified, then the well-defined myeloproliferative disorders having an extra- C chromosome, have been looked over again through the litterature. In each of our three studies we can think that these myelodysplasia are real mysloproliferative disorders because of the same marker extra-chromosome, but even after nine months we did'nt observe any chromosomal sign of blastic transformation.
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PMID:[Refractory sideroblastic anemia, three cases with the same extra marker chromosome (47, Mar +) (author's transl)]. 32 46

A number of disease states are considered "preleukemic" because they carry a significantly increased risk for the subsequent development of frank leukemia. These include a variety of cytopenias, myeloproliferative disorders, and childhood syndromes. Cytogenetic data suggest that these preleukemic disorders may not be qualitatively different from leukemia but simply represent quantitative differences in the degree of selective growth advantage enjoyed by a proliferating abnormal hemic population. Recent chromosome studies have indicated that a) this proliferation is characteristically clonal in both preleukemia and leukemia, apparently resulting from a heritable change in a marrow stem cell that allows it to escape to some degree from normal growth regulation; b) genetic instability in the clone, with additional genetic change, may often underlie clinical progression from the relative indolence of preleukemia or chronic leukemia to an aggressive stage comparable to acute leukemia; and c) certain specific chromosome segments carry genes important in the acquisition of growth advantage by hematopoietic stem cells, and many of these are common to both preleukemia and leukemia. Expansion of hemic clones may also be influenced significantly by alterations in the growth control mechanisms themselves. For instance, in various preleukemic states, preexisting marrow hypoplasia may permit clones with only minimal selective advantage to reach demonstrable size. Chromosome findings may help to establish the diagnosis and prognosis in preleukemic disorders, but additional long-term data are needed.
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PMID:Preleukemia. Cytogenetic clues in some confusing disorders. 33 94

The classification of acute leukemia has almost invariably been based on the morphologic diagnosis into two broad categories: acute lymphocytic and acute myeloid leukemia. Despite the wide range of morphologic variation in both groups, strict criteria to define the subgroups have only recently been proposed. The conventional markers for B and T cells are now being applied to leukemic cells as are cytochemistry and electron microscopy, terminal deoxynucleotidyl transferase, serum lysozyme, and surface markers, E-rosettes, membrane immunoglobulin, antinull acute lymphocytic leukemia antiserum, and Fc and C3 receptors. The myelodysplastic syndromes may mimic acute leukemia and it is important that they be identified and treated appropriately. The high incidence with which chronic myelomonocytic leukemia terminates in acute leukemia suggests that it is a preleukemic condition, whereas refractory anemia with excess blasts and acquired idiopathic sideroblastic anemia may have long, drawn-out courses. Only a small population of patients with the latter conditions develop acute leukemia.
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PMID:Classification of acute leukemia. 33 70

The production of white blood cells is mediated by cellular communication. Proliferation and differentiation of granulocytic and monocytic progenitor and immature cells have been studied in detail and are regulated by stimulatory and inhibitory molecules produced and released from the progeny of the progenitor cells. The resultant interactions between cells and cell-derived molecules suggest operable positive and negative feed-back mechanisms during normal hematopoiesis, and what one sees in the end is the net result of these interactions. The complexities of cellular regulation are partially unravelled by physical separation of the different populations and biochemical analysis of the regulatory molecules. Subpopulations of granulocyte-monocyte progenitors (CFU-c) exist and evidence suggests that they vary in responsiveness to different molecules. Stimulatory molecules are themselves chemically and physically heterogenous and, until recently, believed to have similar biological actions, but this concept must be re-evaluated. Different molecules may activate different subsets of progenitor cells, and there is now a role for substances which enhance the stimulatory interactions. Many studies on normal and leukemic cell responsiveness to stimulation must be re-examined in light of this recent information. Several inhibitory substances operate during normal hematopoiesis. Mature granulocytes, progeny of CFU-c, appear to elaborate at least two inhibitory activities. One activity influences immature, recognizable granulocytes and the other indirectly reduces progenitor cell proliferation by decreasing the production and release of molecules which stimulate CFU-c. In addition, mononuclear phagocytes produce and release E-type prostaglandins in direct response to elevated levels of the stimulatory molecules and E-type prostaglandins counteract increased stimulatory levels by decreasing the sensitivity of CFU-c to stimulators. Much of our present level of sophistication derives from in vitro experimentation and it is apparent that we are only beginning to understand these inter-relationships and their relevance to the in vivo situation. However, these in vitro studies have shed light on the interactions occurring during leukemia. Leukemic cells retain the capacity to respond to normal regulators and must therefore be considered dependent rather than autonomous neoplasms. Abnormalities do exist in leukemic cell interactions: the progenitor cells themselves may be defective and leukemic cells may respond to molecules which normal cells do not. The degree of sensitivity to stimulators and inhibitors will have to be carefully investigated to determine if and what differences may exist between normal and leukemic cells. Normal mature granulocyte derived inhibitory activity is quantitatively deficient in leukemic cells but another inhibitory activity which appears to be specifically present in cells from patients with leukemia and some cases of myelodysplasia is present...
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PMID:Communication between white cells and the abnormalities of this in leukemia. 36 38

Using a Toshiba GC-401 gamma camera with MDS computer Trinary a new method was developed for subtracting the extrarenal (extracanalicular) "background" from the count rate recorded over the kidneys after intravenous administration of 131I-hippurate. Mean subtraction factors of the "blood" activity curve were calculated from a study of 27 patients who were given 51Cr-HSA for purposes of conventional renography with "background" subtraction. The values of the mean subtraction factors FR,L for the right and left kidney, by which a blood count rate should be multiplied amounted to 0.86 +/- 0.12 and 0.79 +/- 0.13, respectively. A comparison of the coefficients of variation of the pure renal signal when mean vs. individually determined subtraction factors were used, and the verification of the method in unilaterally nephrectomized patients have demonstrated that determination of the factors, FR,L, for each patient individually is not required and sufficient precision can be obtained by using the method and factors reported in this study.
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PMID:A method for subtraction of the extrarenal "background" in dynamic 131I-hippurate renoscintigraphy. 37 22

A 53-year-old male developed acute erythroleukemia three years after renal transplantation. He had received three years of immunosuppressive therapy with azathioprine. A preleukemia phase associated with chromosome abnormalities was recognized. Azathioprine has been associated with chromosome abnormalities. The chronic stimulation of an abnormal erythroid clone by transplantation may have hastened the development of erythroleukemia.
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PMID:Erythroleukemia in a renal transplant recipient. 37 1

Certain physical, psychological and social characteristics of 20 adolescents with myelodysplasia are compared to those of age and gender-matched controls. In addition to the obvious physical differences the areas of greatest concern are self-esteem and social-sexual adjustment. Family relations, feelings, and modes of expression were not different in the two groups. Lack of appropriate chores, decreased opportunities to interact and compete with peers, plus uncertainties to interact and compete with peers, plus uncertainties about bowel and bladder continence appear to be the greatest impediments to emotional growth in this physically handicapped group of teenagers. Early recognition of such problems and finding strategies to overcome them are important aspects of the comprehensive care of any person with a chronic disability.
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PMID:Adolescents with myelodysplasia: impact of physical disability on emotional maturation. 37 4


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