Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Mature polymorphonuclear neutrophilic leukocytes (PMNL) from a 2.5-year-old female with infantile chronic myelogenous leukemia (CML) were stimulated with phorbol myristate acetate or opsonized zymosan. The resulting enzymatic NADPH oxidation and the cellular O2- release and luminol-enhanced chemiluminescence were measured. The patient's PMNL responded normally in all respects. Thus, mature infantile CML PMNL undergo a normal respiratory burst following either soluble or particulate stimulation. Our review of the literature emphasizes the importance of studying a well-defined population of PMNL in patients with myelodysplasia.
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PMID:Oxidative metabolism of circulating neutrophils in infantile (Philadelphia chromosome-negative) chronic myelogenous leukemia. 315 49

A 67-year-old woman investigated because of 'myelodysplastic syndrome' was found to have a 4-fold increase in G-6-PD activity in her erythrocytes. The enzyme was partially purified and characterized. On grounds of: (a) reduced electrophoretic mobility, (b) abnormal cathodic band(s) in isoelectrofocusing, (c) increased Michaelis constant for glucose 6-phosphate, (d) abnormal thermostability, and (e) abnormal interaction with the ligand NADPH, we conclude that this is a new structural variant which we designate G-6-PD Verona. G-6-PD Verona was the sole apparent source of G-6-PD activity in the patient's erythrocytes; by contrast, the patient's fibroblasts had only normal G-6-PH (type B). The patient's haematological course terminated into acute myeloid leukaemia. We believe G-6-PD Verona was the result of a somatic mutation in an X-chromosome which took place in a haemopoietic cell clone which subsequently underwent neoplastic transformation.
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PMID:A new glucose 6-phosphate dehydrogenase variant (G-6-PD Verona) in a patient with myelodysplastic syndrome. 657 92

f-Met-Leu-Phe-stimulated luminol-enhanced chemiluminescence was found to be repeatedly defective in some MDS patients. This defect was not attributed to myeloperoxidase deficiency, nor to a defect in NADPH oxidase function, because PMA chemiluminescence was found to be normal in these individuals. An arbitrary value of 7 mV (half the mean control value) was chosen to subdivide the group: MDS patients with values < 7 mV had a mean f-Met-Leu-Phe chemiluminescence response of 2.5 +/- 0.5 compared to MDS patients with values > 7 mV who had a mean response of 15.6 +/- 1.6 mV, P < 0.01 (healthy controls 14 +/- 2 mV). The characteristics of the f-Met-Leu-Phe receptor and initial calcium flux results suggested that the receptor itself was normal in number and function in low f-Met-Leu-Phe responders. The rate of superoxide generation, which is calcium-dependent, was also found to be in the normal range in low f-Met-Leu-Phe responders, although total superoxide production was reduced in some of these patients. When MDS neutrophils with a low f-Met-Leu-Phe response were stimulated with PMA, chemiluminescence was normal, suggesting normal activity of the NADPH-oxidase complex. Furthermore, myeloperoxidase activity was reduced in only three out of the 11 low f-Met-Leu-Phe responders. Following priming with GM-CSF, f-Met-Leu-Phe chemiluminescence was 27 +/- 1.6 mV in low f-Met-Leu-Phe responders compared to controls (87.7 +/- 11 mV, P < 0.005). Thus, although responses were improved, they were not as marked as in control neutrophils. These data suggest that a subgroup of MDS patients have a low f-Met-Leu-Phe chemiluminescence response which is not due to a defect in the f-Met-Leu-Phe receptor or oxidase activity, and in the majority of cases MPO activity is normal. Initial patient survival data suggest that these patients may have an increased risk of infective mortality. It is proposed that defective f-Met-Leu-Phe chemiluminescence results from a putative defect in cell-signalling mechanism upstream of PKC, and GM-CSF priming only partially improves responsiveness.
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PMID:Identification of a subgroup of myelodysplastic patients with a neutrophil stimulation-signalling defect. 791 69

The molecular pathogenesis of therapy-related acute myeloid leukaemia/myelodysplastic syndrome (t-AML/MDS) remains uncertain. However, clonal haemopoiesis may develop following stem cell transplantation and precede the development of t-AML/MDS. Moreover, accelerated telomere shortening may be induced by replicative stress or oxidative damage, leading to genomic instability, and inactivating polymorphisms of the gene encoding NADPH-quinone oxidoreductase (NQO1) are more frequently observed in patients with t-AML. We studied clonal haemopoiesis, telomere length and NQO1 status in 146 patients receiving conventional chemotherapy for non-myeloid malignancies. Clonal haemopoiesis was demonstrated in eight of 98 (8%) patients. Telomere length was reduced in patients following chemotherapy (n = 52) compared with controls (n = 42) (P < 0.001), particularly in those with clonal haemopoiesis (P < 0.002). Whilst there was a trend towards telomere shortening in control subjects polymorphic for NQO1-187Ser (n = 12), chemotherapy-exposed patients polymorphic for the NQO1-187Ser allele (n = 29) had significantly shorter telomeres (P < 0.001). Furthermore, chemotherapy-treated patients with the NQO1-187Ser, polymorphism were more likely to develop clonal haemopoiesis than patients with wild type NQO1 (odds ratio = 7; 1.16-42.6). We conclude that a switch to clonal haemopoiesis may occur after conventional chemotherapy and lead to accelerated telomere shortening. Patients with the NQO1-187Ser polymorphism have an increased risk of developing both clonal haemopoiesis and telomere shortening, which may partly explain the predisposition to t-AML in NQO1-187Ser null individuals.
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PMID:Clonal haemopoiesis may occur after conventional chemotherapy and is associated with accelerated telomere shortening and defects in the NQO1 pathway; possible mechanisms leading to an increased risk of t-AML/MDS. 1519 33

A role for intracellular ROS production has been recently implicated in the pathogenesis and progression of a wide variety of neoplasias. ROS sources, such as NAD(P)H oxidase (Nox) complexes, are frequently activated in AML (acute myeloid leukemia) blasts and strongly contribute to their proliferation, survival, and drug resistance. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of disorders characterized by ineffective hematopoiesis, with an increased propensity to develop AML. The molecular basis for MDS progression is unknown, but a key element in MDS disease progression is the genomic instability. NADPH oxidases are now recognized to have specific subcellular localizations, this targeting to specific compartments for localized ROS production. Local Nox-dependent ROS production in the nucleus may contribute to the regulation of redox-dependent cell growth, differentiation, senescence, DNA damage, and apoptosis. We observed that Nox1, 2, and 4 isoforms and p22phox and Rac1 subunits are expressed in MDS/AML cell lines and MDS samples, also in the nuclear fractions. Interestingly, Nox4 interacts with ERK and Akt1 within nuclear speckle domain, suggesting that Nox4 could be involved in regulating gene expression and splicing factor activity. These data contribute to the elucidation of the molecular mechanisms used by nuclear ROS to drive MDS evolution to AML.
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PMID:Nuclear Nox4-derived reactive oxygen species in myelodysplastic syndromes. 2471 67