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Query: UMLS:C0023418 (leukemia)
 93,477 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The term "asbestos" has a commercial/industrial derivation limited to naturally occurring fibrous minerals of the serpentine or amphibole series. Chrysotile is the only type of asbestos in the serpentine series, whereas the amphibole series is represented by actinolite, amosite, anthophyllite, crocidolite, and tremolite. The essential characteristic of asbestos minerals is their fibrous nature. Large portions of the population ingest asbestos through consumption of food and water. Asbestos or asbestos-like fibers may gain access to water supplies as a result of mining (Lake Superior), from the presence of natural serpentine or amphibole deposits in watersheds (Seattle, WA, and San Francisco, CA) or, under certain conditions, through the use of asbestos-cement pipes for municipal water supplies. For the latter, erosion of the pipe with release of fibers is associated with the "aggressiveness" of the water, a term representing a mathematical expression of pH, alkalinity, and calcium content. The EPA estimated that 68.5% of water systems in the United States utilize water that is potentially capable of eroding asbestos-cement pipe. Carcinogenesis studies of amosite asbestos alone or in combination with the intestinal carcinogen 1,2-dimethylhydrazine dihydrochloride (DMH) were conducted in male and female rats. Amosite asbestos was administered at a concentration of 1% in pelleted diet for the entire lifetime of the rats, starting with the dams of the study animals. One group of amosite asbestos-exposed rats (amosite preweaning gavage) also received chrysotile asbestos via gavage during lactation. Group sizes varied from 100 to 250. Litter size was the same, but the offspring from mothers exposed to amosite asbestos were smaller at weaning than those from nonexposed mothers and remained smaller throughout their life. The DMH was administered by gavage at a dose of 7.5 mg/kg for males and 15 mg/kg for females every 14 days, starting at 8 weeks of age, for a total of five doses. The administration of DMH did not affect body weight gain either in amosite-exposed or nonexposed animals. The amosite-exposed rats showed enhanced survival compared with that of the nonexposed rats. DMH exposure reduced survival by approximately 1 year, although the survival of the amosite plus DMH groups was slightly greater than that of the DMH group alone. Significant increases in the incidences of C-cell carcinomas of the thyroid gland (untreated control, 11/117; amosite, 50/246, P<0.05; amosite preweaning gavage, 14/100) and of leukemia (38/117; 106/249, P<0.05; 49/100, P<0.01) in male rats were observed in amosite-exposed groups. However, the biologic significance of the C-cell carcinomas in relation to amosite asbestos exposure is discounted because of a lack of significance when C-cell adenomas and carcinomas were combined and because the positive effect was not observed in the amosite preweaning gavage group. The biologic significance of an increased incidence of leukemia is questionable because of a lack of statistical significance in the amosite group when evaluated by life table analysis and because no toxic lesions were observed in the target organs, i.e., gastrointestinal tract and mesothelium. DMH caused a high incidence (62%-74%) of intestinal neoplasia in amosite-exposed and nonexposed groups. Neither an enhanced carcinogenic nor a protective effect was demonstrated by exposure to amosite asbestos. Conclusions: Under the conditions of these feed studies, amosite asbestos was not overtly toxic, did not affect survival, and was not carcinogenic when ingested at a concentration of 1% in the diet by male or female F344/N rats. The cocarcinogenic studies using DMH were considered inadequate because of the high incidence of DMH-induced intestinal neoplasia in both the amosite asbestos-exposed and nonexposed groups. Levels of Evidence of Carcinogenicity: Amosite Asbestos: Male Rats: Negative. Female Rats: Negative. Amosite Asbestos + DMH: Male Rats: Inadequate. Female Rats: Inadequate. Note: Amosite Asbestos was previously tested in Syrmosite Asbestos was previously tested in Syrian Golden Hamsters administered in feed (See TR-249, reported 1983).
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PMID:NTP Toxicology and Carcinogenesis Studies of Amosite Asbestos (CAS No. 12172-73-5) in F344/N Rats (Feed Studies). 1274

New treatments in hematological malignancies were a focal point of sessions and presentations at the 42nd Annual Meeting of the American Society of Hematology, held December 15, 2000, in San Francisco, California, U.S.A. The meeting also provided discussion on pathogen inactivation in blood banking, stem cell transplantation in leukemia as well as nonmalignant diseases, the reparative potential of stem cells, a new oral antithrombotic therapy and a new class of highly selective factor Xa inhibitors.
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PMID:Latest advances from basic and clinical research in hematology. 1281 8

Exposure of bobcats (Lynx rufus) and gray foxes (Urocyon cinereoargenteus) to a range of common canine and feline pathogens was assessed in urban and rural zones of Golden Gate National Recreation Area, a National Park in the San Francisco Bay Area, (California, USA) from 1992 to 1995. Testing included serology for canine distemper virus, canine parvovirus (CPV), canine adenovirus, Leptospira interrogans, feline calicivirus (FCV), feline panleukopenia virus, feline herpesvirus, feline enteric coronavirus (FECV), feline immunodeficiency virus, feline leukemia virus, Toxoplasma gondii, and Bartonella henselae. Testing was also performed for Dirofilaria immitis. Significantly more gray foxes were seropositive for CPV in the urban zone than in the rural zone. In addition, radio-tracking of gray foxes in the rural zone indicated that all three of the rural CPV-seropositive foxes had traveled into adjoining small towns, whereas only one of the 11 seronegative animals had done so. Significantly more bobcats were seropositive for FCV in the rural zone than in the urban zone. Individual bobcats with positive FCV antibody titers had patterns of movement that intercepted park inholdings where domestic cats lived. Bobcat samples were seronegative for all five of the other viral feline pathogens, with the exception of a FECV-seropositive bobcat. High seroprevalence was detected for B. henselae and T. gondii in both zones. Variation in the seroprevalence for different pathogens might be related to differences in the exposure of bobcats and foxes to domestic animals: in the urban zone, gray foxes were located in residential areas outside the park, whereas bobcats were not. Although for most of the pathogens examined there was no relationship between urbanization and exposure, our results for CPV in foxes and FCV in bobcats indicated that proximity to urban areas or contact with humans can increase the risk of disease exposure for wild carnivore populations. Combining behavioral information from radio-tracking with data on pathogen exposure or disease incidence can provide valuable insights into the ecology of wildlife disease that might be missed with broad-scale, population-level comparisons alone.
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PMID:Exposure to feline and canine pathogens in bobcats and gray foxes in urban and rural zones of a national park in California. 1513 84

A simple and direct analysis of the spatial distribution of childhood leukemia was performed using geographic data from a large case/control study. The data consist of cases of childhood leukemia and their corresponding birth cohort controls located in seven San Francisco Bay Area counties. Both parametric and randomization analyses show no evidence of a non-random spatial pattern of childhood leukemia among six of these counties. The data from San Francisco County, however, produce a moderately small significance probability (0.08) arising from a distance analysis and a significant p-value (0.01) arising from a frequency analysis of concordant case pairs. Although these p-values accurately reflect the probability of the observed spatial pattern occurring by chance alone, these results are based on only four cases of leukemia.
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PMID:Spatial analysis of childhood leukemia in a case/control study. 1572 36

Recent advances in the treatment and management of haematological malignancies are due in large part to an improved understanding of the basic biology that drives tumour cell growth and survival. This improved understanding has led to the clinical study and approval of a number of different targeted agents across a number of different haematological tumours. This review of clinical data covers some of the exciting clinical advances that were reported at the recent American Society of Hematology meeting in San Diego, USA. This paper focuses on three important areas of biological research that has yielded clinical trials that have affected clinical outcomes. The areas covered include proteasome inhibition and myeloma, tyrosine kinase inhibitors that are directed at the BCR-ABL fusion protein and chronic myeloid leukaemia/acute lymphoblastic leukaemia, and FLT3 inhibitors and acute myeloid leukaemia acute lymphoblastic leukaemia therapy.
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PMID:Targeted therapy for haematological malignancies: clinical update from the American Society of Hematology, 2004. 1614

Highly active antiretroviral therapy (HAART) has dramatically reduced the incidence of acquired immunodeficiency syndrome (AIDS) and increased AIDS survival time, but little is known about its impact on cancer. Data from adults in the San Francisco, California, AIDS surveillance registry were computer matched with the California Cancer Registry. Age-, sex-, and race-adjusted standardized incidence ratios (SIRs) were computed, and proportional hazards models evaluated the effect of HAART use on cancer incidence and cancer survival time. Among 14,210 adults with AIDS diagnosed in 1990-2000, 482 non-AIDS-defining cancers were diagnosed. Compared with rates for the general population, significantly increased cancer incidence rates were observed for anal (SIR = 13.4), Hodgkin's lymphoma (SIR = 11.5), liver (SIR = 3.6), oral cavity and pharynx (SIR = 2.6), respiratory (SIR = 2.6), leukemia (SIR = 2.4), skin melanoma (SIR = 2.4), and prostate (SIR = 1.7) cancers. Risk of liver cancer was lower with HAART use (relative hazard (RH) = 0.32). Risk of anal cancer increased after 1995 (RH = 2.9). Respiratory cancer (RH = 0.40) and Hodgkin's lymphoma (RH = 0.17) showed increased cancer survival time with HAART use, while anal cancer survival may have been slightly decreased (RH = 1.4). The impact of HAART on non-AIDS-defining cancer incidence rates and survival is not uniform, and the mechanism(s) responsible for these differences should be investigated further.
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PMID:The impact of highly active antiretroviral therapy on non-AIDS-defining cancers among adults with AIDS. 1734 4

Ever since the discovery of cancer stem cells in leukemia and, more recently, in solid tumors, enormous attention has been paid to the apparent stem cell nature of cancer. These concepts were the focus of the "Stem Cells and Cancer" symposium held recently at the University of California, San Francisco, and the inspiration for this overview of current research and important questions emerging in this area.
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PMID:Cancer and stem cell biology: how tightly intertwined? 1868 38

In Central America, nearly 70% of pediatric cancer is related to hemato-oncologic disorders, especially acute lymphoblastic leukemia (ALL). Preliminary studies have described a high incidence of childhood leukemia in these countries; however, no molecular analyses of these malignancies have yet been carried out. We studied diagnostic samples from 84 patients from the National Children's Hospital in San Jose, Costa Rica (65 precursor B-ALL, 5 T-cell ALL, and 14 acute myeloblastic leukemia). Our methodology included cytogenetic, fluorescent in situ hybridization, and polymerase chain reaction approaches. The observed rate of leukemia was 52.2 cases per million children per year. Twelve out of 65 (18.4%) precursor B-ALL tested positive for TEL-AML1 and 3 cases for BCR-ABL (4.6%). In addition, we detected 2 patients carrying an E2A-PBX1 transcript (3.1%) and 1 patient with an MLL-AF4 fusion gene (1.5%). None of the T-cell ALL cases were positive for either SIL-TAL1 or HOX11L2. Within 14 acute myeloblastic leukemia patients, we confirmed 2 cases with FLT3-internal tandem duplication+, 1 patient with AML1-ETO, and only 1 case carrying a PML-RARalpha rearrangement. The present study confirms the relatively high incidence of pediatric leukemia in Costa Rica and constitutes the first report regarding the incidence of the main molecular alterations of childhood leukemia in our region.
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PMID:Molecular and epidemiologic findings of childhood acute leukemia in Costa Rica. 1919

Abandonment of therapy is one of the most common causes of treatment failure among children with cancer in low-income countries. Our objectives were to describe the prevalence and predictors of abandonment among such children with cancer in El Salvador. We analyzed data on patients younger than 16 years, diagnosed with any malignancy between January 2001 and December 2003 at the Benjamin Bloom National Children's Hospital, San Salvador. Among 612 patients, 353 were male (58%); the median age at diagnosis was 5.1 years; 59% of patients were diagnosed with leukemia/lymphoma, 28% with solid tumors and 13% with brain tumors. The prevalence of abandonment was 13%. Median time to abandonment was 2.0 (range 0-36) months. In univariate analyses, paternal illiteracy [odds ratio (OR) 3.8, 95% confidence interval (CI) 2.0-7.2; p = 0.001]; maternal illiteracy (OR = 5.1, 95% CI 2.5-10; p < 0.0001); increasing number of household members (OR = 1.2, 95% CI 1.1-1.3; p = 0.004); and low monthly household income (OR per $100 = 0.59, 95% CI 0.45-0.75; p < 0.0001) all significantly increased the risk of abandonment, whereas travel time to hospital did not. In multiple regression analyses, low monthly income and increased number of people in the household were independently predictive of abandonment. In conclusion, in El Salvador, despite the provision of free treatment, socioeconomic variables significantly predict increased risk of abandonment of therapy. Understanding the pathways through which socioeconomic status affects abandonment may allow the design of effective interventions.
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PMID:Prevalence and predictors of abandonment of therapy among children with cancer in El Salvador. 1958 96

The objectives of this study were to characterize temporal patterns of magnetic fields (Bavg) and two measures of neutral-to-earth voltage: the voltage between the water line and earth (VW-E), and the voltage between bathtub plumbing fixtures and the drain (Vbath). The latter is a source of exposure to contact current in bathing children that has been proposed to explain the reported association between power-frequency magnetic fields and childhood leukemia. These quantities were measured each minute in a sample of 15 single-detached residences in San Jose, CA. Generally, Bavg, VW-E, and Vbath were positively correlated with each other within residences, and displayed similar diurnal patterns. Weekday and weekend patterns displayed qualitative differences that reflect the more scheduled workday for weekdays, and a less structured pattern for weekends. When pooled with two prior measurement studies, positive associations across residences between Bavg and both VW-E and Vbath were observed. Home designs over the past 30-40 years have lead to a decreasing prevalence of Vbath as conductive drains have been swapped out for non-conductive materials. Nonetheless, the observed relationships within and across residences indicate that contact current has the characteristics of a factor that could explain the association of magnetic fields with childhood leukemia.
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PMID:Residential magnetic fields and measures of neutral-to-earth voltage: variability within and between residences. 1974 62


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