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

The ultrastructure and adenine nucleotide metabolism of platelets from patients with acute leukemia were studied to elucidate possible mechanisms for the platelet dysfunction observed in this clinical setting. Nonstimulated (resting) platelets from leukemic patients varied greatly in size; exhibited marked variation in the number of alpha granules present per cell; had poorly delineated circumferential bands of microtubules; and often grossly dilated open channel systems or cytoplasmic vacuolization. The intracellular concentrations of ATP and ADP were significantly below normal, and the specific radioactivity of ATP and ADP of nonstimulated platelets in leukemia was equivalent to or exceeded that seen in stimulated normal platelets. Addition of ADP or collagen to platelets from leukemic patients was followed by retarded and incomplete shape change, delayed and incomplete centripetal migration of subcellular organelles, impaired degranulation, and the formation of loose aggregates composed of relatively few platelets. Stimulation of "leukemic" platelets with collagen led to the release of significantly subnormal amounts of ATP and ADP and no significant change in the specific radioactivity of the intracellular nucleotides. In contrast to the results in normal platelets, the conversion of ATP to inosine monophosphate and hypoxanthine in platelets in leukemia failed to increase significantly with collagen stimulation. The results indicate that abnormalities exist in the storage pool of adenine nucleotides and the release mechanism of platelets in acute leukemia. These defects appear to contribute to an impairment in the release reaction in these platelets. Many of the ultrastructural and metabolic defects seen in acute leukemia occur in platelets in preleukemia.
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PMID:The platelet defect in leukemia. Platelet ultrastructure, adenine nucleotide metabolism, and the release reaction. 4 18

We have conducted extensive morphologic studies of the platelets in 16 patients with preleukemia or myelomonocytic leukemia. Although the degree and frequency of the changes varied in the different cases, it was evident that the platelets in these two pathologic states often were structurally abnormal. The abnormalities include changes in size (mainly giant forms), shape (frequent presence of round cells), and quantitative (particularly decreases) as well as qualitative changes in the platelet granules. Quite remarkable has been the finding of giant granules of irregular contour and heterogeneous composition, perhaps the result of fusion of several single granules. Other changes have included overabundance of the membranous systems of the platelet.
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PMID:The ultrastructure of the platelets in refractory anemia ("preleukemia") and myelomonocytic leukemia. 4 77

Particles with the density and enzymatic activity characteristic of known oncornavirus have been previously described in bone marrow cells from patients with leukemia in relapse and in remission. We have confirmed these findings and studied two patients in whom preleukemia was among the diagnostic considerations. Following cultivation of bone marrow from these patients for 1 week in conditioned media with dexamethasone, a high-speed pellet of the supernatant fluid and disrupted cells was prepared and analyzed on a sucrose gradient for enzymatic activity characteristic of RNA-directed DNA polymerase (reverse transcriptase). Peaks of endogenous DNA polymerase activity showing ribonuclease sensitivity and/or stimulation with the synthetic template poly(rC)-(dG)12-18 were demonstrated in both patients at densities of 1.15 to 1.19 and 1.21 to 1.24 g/ml. Subsequently, diagnosis 2 and 4 months after initial evaluation revealed acute myelogenous leukemia and malignant histiocytosis, respectively. Prior studies have suggested a possible etiological significance of such particles in human leukemia. The demonstration of similar particles preceding clinically overt disease in these patients supports this hypothesis and offers the possibility of early diagnosis and treatment.
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PMID:Oncornavirus-like particles from cultured bone marrow cells preceding leukemia and malignant histiocytosis. 5 58

Cytogenetic studies indicate that most tumors are clonal (i.e. unicellular in origin) and have karyotypic alterations. These are not consistent, but non-random abnormalities are being increasingly identified by banding techniques, pointing to the sites on human chromosomes where genes important in neoplastic development are located. It is postulated that tumor progression occurs as a result of genetic lability within the neoplastic clone, leading to emergence of increasingly mutant subpopulations (often recognizable cytogenetically) with more malignant properties. In the context of this hypothesis, acute leukemia, chronic leukemia, and preleukemia can be viewed as differing only in the rate at which an abnormal hemic clone is expanding, with progression to a more aggressive phase (e.g. the "blast crisis" of chronic granulocytic leukemia) reflecting emergence of a new predominant subpopulation as the result of an additional genetic change. These concepts, and the cytogenetic data from which they have been derived, may help our understanding of basic tumor biology, and have some practical applications in the diagnosis of human neoplasms.
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PMID:Tumors as clonal proliferation. 10 6

Acute nonlymphocytic leukemia (ANLL) is preceded by a hematologic illness representing the "preclinical" stages of the disease in many patients. This "preclinical stage" or preleukemic stage is difficult to recognize by conventional hematologic morphologic techniques. A prospective study was carried out to determine whether cytogenetic studies would be helpful in the recognition of preleukemic states and whether the presence of cytogenetic abnormalities would have prognostic significance. A study of 284 patients with suspected preleukemia has yielded 62 patients with progression to overt ANLL. Cytogenetic abnormalities were found in 30% of suspected preleukemic patients, whereas 53% of the patients progressing to acute leukemia had cytogenetic abnormalities. These studies show that the presence of cytogenetic abnormalities aid in the recognition of preleukemia but are not specific for early leukemia. Patients with cytogenetic abnormalities are more likely to develop overt ANLL. Banded chromosome studies demonstrated cytogenetic abnormalities in the preleukemic phase in 13 of 26 patients. A variety of clonal chromosomal abnormalities were observed.
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PMID:Preleukemic syndromes. 10 8

Disturbed micturition of the neurogenic type is found in children suffering from spinal tumors and anomalies of the vertebral column. The most frequent cause is the so-called myelomeningocele. Myelodysplasia can occur in 1-2 out of every 1,000 new-born babies. Operative treatment is available today (closing the celes immediately after birth and drainage of the associated hydrocephalus) so that these children survive and their fate essentially depends on the early diagnosis and therapy of the neurogenic micturition disturbance. Urodynamic examinations and the determination of the urethra pressure profile are vital for diagnosis. Using the results four different groups can be established each requiring a specific therapy. Individual therapies must also be selected for each individual case. Apart from operative treatment, drugs and electrostimulation can be used on a large scale. The authors present their own experience and results with regard to diagnosis and therapy.
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PMID:[Neurogenic disorders of bladder emptying in children]. 12 96

The authors present the results of psychosomatic follow-up examinations performed on 40 children after myelodysplasia, hydrocephalus and craniostenosis operations. A total of 60 percent showed average intelligence (suitable for ordinary schools) despite considerable motor disturbances, and 27.5 percent could attend special schools. Psychic and somatic development was further differentiated using such criteria as concentration, vocabulary, running, incontinence and social conditions.
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PMID:[Psychologic development of children with surgically treated myelodysplasias, craniostenoses and hydrocephalus]. 12 97

Published data on Japanese leukemia patients with a preleukemic hematological disorder were assessed. The reexamined cases were from the "Japona Centra Revuo Medicina" reported during the period from 1952 to 1971. Among preleukemic hematological disorders, hypoplastic anemia was the most frequently reported (41 of 62 cases). These "hypoplastic preleukemia" patients were rather elderly and terminated mostly in atypical myelocytic leukemia. The chief hematological feature of the hypoplastic preleukemia cases was the coexistence of a relative erythroid hyperplasia and a slight increase of myeloblasts in the bone marrow that was unusual in hypoplastic anemia. The presence of pancytopenia and hypocellular marrow with a relative erythroid hyperplasia combined with a slight increase of myeloblasts probably indicates hypoplastic preleukemia that terminates later in acute leukemia.
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PMID:Preleukemia: hematological disorders prior to onset of leukemia. 13 44

Contrast demonstration of the distal dural sac and its contents is essential for an understanding of the regional pathology in cases of occult or previously operated non-occult forms of lumbar myelodysplasia. Only in this way is it possible to demonstrate the position of the conus medullaris, the course of the nerve roots, thickening of the filum terminale or other soft tissue abnormalities. Of various methods, the most detailed information can be obtained by the use of water soluble contrast injected after careful, high lumbar puncture (L 2/3). This is illustrated in five cases in which Dimer X was used. In view of its proven low neurotoxicity, Amipaque, which is now available in Germany, will be used in future.
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PMID:[Myelography with water soluble contrast for malformations of the conus medullaris and filum terminale (author's transl)]. 14 2

Adenylate-kinase (AK) interacts in the balance of phosphate acceptors and donators. With respect to the polymorphism of enzyms of erythrocytes there can be assumed a system of two co-dominate allels determined by the genotype of AK 1 and AK 2 with the phenotypes of AK 1-1, AK 2-1 and AK 2-2. The distribution of AK within 108 cases of MDS and 90 controls was examined. AK 2-1 was found in about 30% of bipolar MDS, but in no case of unipolar MDS or controls. The possible relations were discussed demonstrating a synopsis of the pathogenesis of MDS.
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PMID:[Adenylat-kinase-Systeme, ein Beitrag zum manisch-depressiven Kranksein (MDK)]. 18 95


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