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)

Secondary MDS, or AL induced by the treatment of another primary disease, occurs at an average of 48-71 months after that treatment. A high percentage of the 2 MDS convert to AL. Survival of either is less than 1 year. A constellation of morphological abnormalities from all three cell lines produces a unique appearance. The 2 AL are difficult to classify by the FAB system. With the exception of cytogenetic analysis, the biology of 2 MDS/AL remains largely unexplored. Alterations of chromosomes 5 and 7 predominate, but other associated cytogenetical abnormalities are increasingly being recognized. A review of the development of 2 MDS/AL in a variety of primary diseases generates the following tentative conclusions: many of the commonly used alkylating agents, and the non-classical alkylating agent procarbazine, are leukaemogens; procarbazine is probably the important leukaemogen in the MOPP programme; cyclophosphamide appears to be a less potent leukaemogen than other alkylating agents; the method in which a drug is administered probably influences its leukaemogenic potential; the duration of therapy with a drug, or the total amount of drug delivered, is probably an important factor in leukaemogenesis; irradiation alone appears to be a weak leukaemogen; irradiation has little or no synergism with chemotherapy in leukaemogenesis; the older patient treated with leukaemogenic drugs is at substantial risk to develop a 2 MDS/AL; most studies show no plateau in the actuarial incidence of developing a 2 MDS/AL, despite lengthy follow-up. Benzene is the only chemical agent for which strong evidence of leukaemogenesis exists. Nonetheless, the similarities in the karyotypic alterations of leukaemic cells between those whose occupations expose them to chemical hazard and those who are exposed to cytotoxic agents lend support to the idea that more environmental leukaemogens have yet to be discovered. Aggressive therapy should be considered for a patient of any age with an adequate performance status and a diagnosis of secondary AL, especially if the karyotype in the malignant cell is predictive of a high response rate. The therapy of 2 MDS remains investigational. To mitigate the development of a leukaemic complication, maintenance therapy should be restricted to diseases in which its efficacy is established or to an investigational setting, and consideration of the leukaemogenic potential of equally effective regimens should be part of the therapeutic planning in the older patient.
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PMID:Secondary myelodysplastic syndromes and leukaemias. 355 47

A large cohort study of 74,828 benzene-exposed and 35,805 unexposed workers employed between 1972 and 1987 in 12 cities in China were followed to determine mortality from all causes and the incidence of lymphohematopoietic malignancies and other hematologic disorders. Benzene-exposed study subjects were employed in a variety of occupations, including painting, printing, and the manufacture of footwear, paint, and other chemicals. All-cause mortality was similar in the benzene-exposed and unexposed comparison group. Statistically significant excess deaths were noted among benzene-exposed subjects for leukemia (RR = 2.3, 95% CP 1.1-5.0), malignant lymphoma (RR = 4.5, 95% CI: 1.3-28.4), and nonneoplastic diseases of the blood (RR = 95% CP 2.5-infinity), and a marginally significant excess was noted for lung cancer (RR = 1.4, 95% CI: 1.0-2.0). Risk was significantly elevated for the incidence of all lymphohematopoietic malignancies (RR = 2.6, 95% CI: 1.5-5.0), malignant lymphoma (RR = 3.5, 95% CI: 1.2-14.9), and leukemia (RR = 2.6, 95% CI.. 1.3-5.7). Among the leukemia subtypes, only acute myelogenous leukemia (AML) incidence was significantly elevated (RR = 3.1, 95% CI: 1.2-10.7), although nonsignificant excesses were also noted for chronic myelogenous leukemia (CML) (RR = 2.6, 95% CI: 0.7-16.9) and lymphocytic leukemias (RR = 2.8, 95% CI.. 0.5-54.5). Significant excesses were found for aplastic anemia (RR = infinity, 95% CI: 2.2-co) and myelodysplastic syndrome (RR = infinity, 95% CI: 1.7-infinity). Employment in benzene-associated occupations in China is associated with a wide spectrum of myelogenous and lymphocytic malignant diseases and related disorders. Investigations continue to assess the nature of these associations.
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PMID:A cohort study of cancer among benzene-exposed workers in China: overall results. 883 74

Benzene is a ubiquitous occupational hematotoxin and leukemogen, but people vary in their response to this toxic agent. To evaluate the impact of interindividual variation in enzymes that activate (i.e., CYP2E1) and detoxify (i.e., NQO1) benzene and its metabolites, we carried out a case-control study in Shanghai, China, of occupational benzene poisoning (BP; i.e., hematotoxicity), which we show is itself strongly associated with subsequent development of acute nonlymphocytic leukemia and the related myelodysplastic syndromes (relative risk, 70.6; 95% confidence interval, 11.4-439.3). CYP2E1 and NQO1 genotypes were determined by PCR-RFLP, and CYP2E1 enzymatic activity was estimated by the fractional excretion of chlorzoxazone (fe(6-OH)) for 50 cases of BP and 50 controls. Subjects with both a rapid fe(6-OH). and two copies of the NQO1 609C-->T mutation had a 7.6-fold (95% confidence interval, 1.8-31.2) increased risk of BP compared to subjects with a slow fe(6-OH) who carried one or two wild-type NQO1 alleles. In contrast, the CYP2E1 PstI/RsaI polymorphism did not influence BP risk. This is the first report that provides evidence of human susceptibility to benzene-related disease. Further evaluation of susceptibility for hematotoxicity and hematological malignancy among workers with a history of occupational exposure to benzene is warranted.
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PMID:Benzene poisoning, a risk factor for hematological malignancy, is associated with the NQO1 609C-->T mutation and rapid fractional excretion of chlorzoxazone. 923 Jan 85

Chronic exposure to high concentrations of benzene is associated with an increased incidence of myelodysplastic syndrome (MDS) and acute myelogenous leukemia (AML). Studies of patients occupationally exposed to benzene show a pattern of cytogenetic aberrations involving loss of all or part of chromosomes 5 and/or 7 as well as trisomy 8 and we have previously reported that hydroquinone (HQ) induces deletions of 5, 7 and 8. Benzene metabolism is a requirement for bone marrow toxicity and the phenolic metabolites, HQ and catechol (CAT), have been implicated in benzene hematotoxicity. A research project was designed to determine whether CAT by itself and in conjunction with HQ could directly induce loss of chromosome 5 and/or 7 and gain of chromosome 8. Using fluorescence in situ hybridization with chromosome-specific 5, 7, and 8 probes we demonstrate that 5 to 150 uM CAT does not produce chromosomal aberrations, however CAT and 25 uM HQ can act in synergy to induce dose dependent loss of these chromosomes. In addition HQ/CAT selectively induces -5q which is not observed for HQ only. These results demonstrate for the first time that CAT/HQ act in synergy to induce specific chromosome loss found in secondary MDS/AML.
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PMID:The benzene metabolites hydroquinone and catechol act in synergy to induce dose-dependent hypoploidy and -5q31 in a human cell line. 1070 50

Benzene is an established cause of human leukemia that is thought to act by producing chromosomal aberrations and altered in cell differentiation. In several recent studies increased levels of chromosomal aberrations in peripheral blood lymphocytes were correlated with a heightened risk of cancer, especially hematological malignancies. Thus, chromosomal aberrations may be a predictor of future leukemia risk. Previous studies exploring whether benzene exposure induces chromosomal aberrations have yielded mostly positive results. However, it remains unclear whether the chromosomal aberrations induced by benzene occur in a distinct pattern. Here, we thoroughly review the major chromosome studies published to date in benzene-exposed workers, benzene-poisoned and preleukemia patients, and leukemia cases associated with benzene expose. Although three cytogenetic markers (chromosomal aberrations, sister chromatid exchanges, and micronuclei) are commonly examined, our primary focus is on studies of chromosomal aberrations, because only this marker has so far been correlated with increased cancer risk. This review surveys the published literature, analyzes the study results, and discusses the characteristics of effects reported. In most studies of currently exposed workers, increases in chromosomal aberrations were observed. However, due to the relatively small number of affected individuals and variability in the reported aberrations, firm conclusions cannot be made about the involvement of specific chromosomes or chromosome regions. Further, in leukemia cases associated with benzene exposure, there is no evidence of a unique pattern of benzene-induced chromosomal aberrations in humans. Leukemia cases associated with benzene exposure are, however, more likely to contain clonal chromosome aberrations then those arising de novo in the general population.
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PMID:The nature of chromosomal aberrations detected in humans exposed to benzene. 1184 14

Benzene is one of wildly used chemicals. Long-term exposure to benzene causes hematotoxicities and further, the development of including anemia, myelodysplastic syndrome (MDS), aplastic anemia, etc., with the leukemia as the worst. People vary greatly in their susceptibility to adverse health outcomes from benzene exposure. The author reviewed the relationship between genetic polymorphism of I metabolic enzymes(CYP2E1, NQO1, MPO) and II metabolic enzymes(GST, PST) involving benzene metabolite and interindividual variation in their genetic susceptibility to hematotoxicity from benzene exposure in this paper.
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PMID:[Individual susceptibility to hematotoxicity from benzene exposure and the genetic polymorphism of metabolic enzymes]. 1256 53

Benzene has been used in various industries as glues or solvents in Korea. Since 1981, a preparation containing more than 1% benzene is not allowed to be manufactured, used or dealt with in the workplace, except in laboratories and in those situations benzene must be used in a completely sealed process as specified in Industrial Safety and Health Act (ISHA). Claims for compensation of hematopoietic diseases related to benzene have been rising even though the work environment has been improved. This study was conducted to assess the status of benzene exposure in different industries in Korea. We reviewed the claimed cases investigated by the Korea Occupational Safety and Health Agency (KOSHA) between 1992 and 2000. The Survey of National Work Environment Status in 1998 was analyzed to assume the number of workers and factories exposed to benzene. In 2000, six factories were investigated to evaluate benzene exposure. Personal air monitoring was performed in 61 workers and urine samples were collected from 57 workers to measure trans,trans-muconic acid (t,t-MA). Hematologic examination has performed. Thirty-four cases of hematopoietic diseases were investigated by KOSHA including eight cases of myelodysplastic syndrome and eight cases of acute myelocytic leukemia. Eight cases were accepted as related to benzene exposure. The number of workers possibly exposed to benzene can be estimated to be 196,182 workers from 6219 factories based on the database. The geometric mean of benzene in air was 0.094 (0.005-5.311) ppm. Seven samples were higher than 1 ppm but they did not go over the 10 ppm occupational exposure limit (OEL) value in Korea. The geometric mean of trans,trans-muconic acid in urine was 0.966 (0.24-2.74) mg/g creatinine. The benzene exposure level was low except in a factory where benzene was used to polymerize other chemicals. The ambient benzene from 0.1 to 1 ppm was significantly correlated with urine t,t-MA concentration (r=0.733, p<0.01). Hematologic parameters did not show significant difference among groups divided into the level of exposure. Korean workers were not highly exposed to benzene and the level of exposure was mostly less than 1 ppm. However, there might be an excessive risk of hematopoietic disorders due to relatively high past exposure. The OEL value of benzene was amended to 1 ppm from 10 ppm in 2002 and was effective since July 2003.
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PMID:Occupational exposure to benzene in South Korea. 1593 1

Benzene can result in bone marrow suppression. Chronic benzene poisoning (CBP) can be found among workers with excessive benzene exposure. CBP could give the appearance of different types of disorders such as leukopenia, agranulocytosis, anemia, pancytopenia, aplastic anemia (AA), myelodysplastic syndrome (MDS), and leukemia. This paper describes 43 CBP cases with the patients' ages ranging from 18 to 36 years (average: 23 years). Among them, 13 (30%) were male and 30 (70%) were female. Their job titles were furniture maker, shoemaker, industrial painter and metal shop worker. Their work durations ranged from 1.5 to 72 months (average: 14 months). Benzene levels in these workplaces exceeded 30 mg/m3. Ten of the 43 cases (23%) were diagnosed as mild cases of CBP, another 10 (23%) were moderate, and 23 (53%) were severe. Treatment for CBP included the following: cessation of benzene exposure, general supportive therapy, antibiotics, vitamins, corticosteroids, androgens, colony-stimulating factors (G-CSF, GM-CSF), blood component therapy, and traditional Chinese medicine. Thirty-three (77%) of the cases recovered completely, nine (21%) cases improved, and one (2%) died. In general, prognosis of CBP cases is optimistic when appropriate treatment is given. However, a few of the benzene-induced AA cases showed no response to treatment, which raises questions about the traditional view of the pathogenesis of the illness. Furthermore, only a part of the population with the same level of benzene exposure would suffer from the disease. Still, CBP cases with the same benzene exposure level exhibited different extents of severity of the illness. This evidence suggests strongly the existence of individual susceptibility. Detection of the biological markers regarding the individual susceptibility would be valuable for screening workers who are not suitable to be exposed to benzene.
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PMID:Clinical analysis of 43 cases of chronic benzene poisoning. 1593 9

Activated sludge was sequentially adapted to benzene, toluene, and o-xylene (BTX) to study the effects on the change of microbial community. Sludge adapted to BTX separately degraded each by various rates in the following order; toluene>o-xylene>benzene. Degradation rates were increased after exposure to repeated spikes of substrates. Eleven different kinds of sludge were prepared by the combination of BTX sequential adaptations. Clustering analyses (Jaccard, Dice, Pearson, and cosine product coefficient and dimensional analysis of MDS and PCA for DGGE patterns) revealed that acclimated sludge had different features from nonacclimated sludge and could be grouped together according to their prior treatment. Benzene- and xylene-adapted sludge communities showed similar profiles. The sludge profile was affected from the point of the final adaptation substrate regardless of the adaptation sequence followed. In the sludge adapted to 50 ppm toluene, Nitrosomonas sp. and bacterium were dominant, but these bands were not dominant in benzene and benzene after toluene adaptations. Instead, Flexibacter sp. was dominant in these cultures. Dechloromonas sp. was dominant in the culture adapted to 50 ppm benzene. Thauera sp. was the main band in the sludge adapted to 50 ppm xylene, but became vaguer as the xylene concentration was increased. Rather, Flexibacter sp. dominated in the sludge adapted to 100 ppm xylene, although not in the culture adapted to 250 ppm xylene. Two bacterial species dominated in the sludge adapted to 250 ppm xylene, and they also existed in the sludge adapted to 250 ppm xylene after toluene and benzene.
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PMID:Change of sludge consortium in response to sequential adaptation to benzene, toluene, and o-xylene. 1809 60

Benzene-caused hematologic neoplasms may be recognized as an occupational disease (OD) according to the German ordinance on ODs. At present, the OD No. 1303 covers heterogeneous diseases and various chemical agents triggering these diseases. The members of the medical advisory board specializing in ODs within the Ministry of Employment and Social Affairs recently proposed excluding "diseases of the blood, the hematopoietic and lymphatic system caused by benzene" from OD No. 1303 and classifying them as a separate OD. Benzene is generally acknowledged as a cause of acute myeloid leukemia, proven by numerous epidemiologic studies. However, there is less epidemiologic evidence of its association with other hematologic neoplasms, notably non-Hodgkin's lymphoma (NHL). To clarify this issue, the experts evaluated international literature and concluded that all kinds of myeloid and lymphoid malignancies including their prestages can be caused by occupational benzene exposure. Hence, physicians should ask patients about occupational benzene exposure and report any kind of diagnosed hematologic neoplasms, including their prestages, as suspected OD. The advisory board considered that a dose range starting from 10 ppm-years (cumulative benzene exposure) is sufficient for a > 50% probability of causing leukemias according to the WHO classification, including chronic lymphatic leukemia, and the potential preleukemias aplastic anemia and myelodysplastic syndrome, but excluding chronic myeloid leukemia (CML). For NHL and myeloproliferative diseases (including CML) the present epidemiologic evidence is considered not to be sufficient to describe a precise dose-effect relationship.
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PMID:[Paradigm change in the assessment of myeloid and lymphoid neoplasms associated with occupational benzene exposure]. 1933 9


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