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

The contamination of cell lines with mycoplasmas is certainly one of the major problems occurring in cultured cells. Analyzing more than 460 human leukemia-lymphoma (LL) cell lines, we found that 28% of the cultures were mycoplasma-positive. Mycoplasmas can produce extensive changes, growth arrest and cell death in the infected cultures. While mycoplasma-infected cell lines can be truly cleansed from the contaminants, all the efforts would be in vain when the cells return to a mycoplasma-infested environment or are handled with unsuitable culture practices. Hence, the main focus of mycoplasma control should be on preventing cell culture contamination. Mycoplasmas can be introduced through several routes including culture reagents and laboratory personnel. Cross-contamination from infected cell cultures within one laboratory continues to be the major source for the spread of mycoplasma. Specific technical protocols and cell culturing guidelines may be followed in order to minimize the risk of mycoplasma contamination of cell lines. This "good culture practice" is of utmost importance as faulty cell culture techniques appear to be also the main reason for the high incidence of cross-contaminated LL cell lines which according to our experience using DNA fingerprinting of some 500 LL cell lines is about 15%.
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PMID:Prevention of mycoplasma contamination in leukemia-lymphoma cell lines. 1177 44

Human leukemia-lymphoma (LL) cell lines represent important tools for experimental research. Among the various problems associated with cell lines, the two most common concern contaminations: (1) cross-contamination with unrelated cells and (2) contamination with microorganisms, in particular mycoplasma. The bad news is that about one-third of the cell lines are either cross-contaminated or mycoplasma-infected or both. The good news is that there are means to recognize and overcome these problems. In cases where, during attempts to establish new LL cell lines, primary LL cultures are cross-contaminated with continuous cell lines, intended new cell lines simply cannot be established ("early" cross-contamination). In cases of "late" cross-contamination of existing LL cell lines where the intrusive cells have a growth advantage, the original ("uncontaminated") cell lines may still be available elsewhere. DNA fingerprinting and cytogenetic analysis appear to be the most suitable approaches to detect cross-contaminations and to authenticate LL cell lines. A different but related aspect of "false" LL cell lines is the frequent misclassification of cell lines whereby the actual cell type of the cell line does not correspond to the purported model character of the cell line. Mycoplasma infection can have a multitude of effects on the eukaryotic cells which, due to the variety of infecting mycoplasma species and many other contributing parameters, cannot be predicted, rendering resulting data questionable at best. Practical procedures for the detection and elimination of mycoplasma contamination have been developed. Diagnostic and preventive strategies in order to hem the alarming increase in "false" and mycoplasma-positive LL cell lines are recommended.
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PMID:Mix-ups and mycoplasma: the enemies within. 1183 74

Mycoplasmal contamination of cell culture systems continues to present major problems for basic research and for manufacturing of bioproducts. Previous work suggested that certain antibiotics have strong anti-mycoplasma properties and raised the prospect that the technically rather simple antibiotic treatment may be an appropriate means for mycoplasma eradication. We have developed and validated an effective strategy to eliminate mycoplasma from chronically infected cell cultures using antibiotics which have shown strong activity against these contaminants. Here, we describe our experience with the treatment of 123 consecutive mycoplasma-positive leukemia-lymphoma cell lines, comparing five different antibiotic regimens (in total 433 treatments). We optimized the antibiotic dose schedules and the duration of treatments. The various antibiotic treatments which were employed in parallel had a high efficacy, as 71% to 86% of the infected cultures were cleansed. Treatment failure may result from the resistance of the mycoplasmas to antibiotic therapy and the inability of the eukaryotic cells to survive the cytotoxic effects of the antibiotics. Resistance to mycoplasma eradication was observed in 3% to 20% of the cultures. Loss of the cell culture caused by cytotoxicity was seen in 3% to 11% of the treatments. With regard to the overall outcome, 96% of the cell lines were rendered mycoplasma-free with at least one of the antibiotic treatments and were permanently cured. In conclusion, antibiotic treatment represents the most practical and efficient option to cleanse mycoplasma-positive cell lines.
Leukemia 2002 Feb
PMID:Elimination of mycoplasma from leukemia-lymphoma cell lines using antibiotics. 1184 Feb 96

The specific, sensitive and reliable detection of mycoplasma contamination in cell cultures is an important part of mycoplasma control. We have sought to develop and validate a method for mycoplasma detection which is sensitive and accurate, but also practical in the sense of time spent, costs, and applicability in the standard laboratory; finally, the method should be suitable for screening large numbers of test specimens. To that end, we adapted a previously developed polymerase chain reaction (PCR) method for daily routine application. This single-step PCR uses a mixture of primers annealing to gene sequences coding for evolutionarily conserved 16S rRNA of different mycoplasma species, including the ones most commonly found in cell cultures. An internal control was introduced to exclude any false-negative tests resulting from technical PCR problems. This mycoplasma detection by PCR has been validated prospectively on 201 consecutive leukemia-lymphoma cell lines received at the institute over a 3-year period and on 118 initially positive cell lines after anti-mycoplasma treatment with antibiotics. The sensitivity (detection of true positives) of this PCR detection assay was 96% and the specificity (detection of true negatives) was also 96%, with positive and negative predictive values (probability of correct result) of 86% and 99%, respectively. PCR defined the mycoplasma status with 96% accuracy (detection of true positives and true negatives). Besides the high sensitivity and specificity, further attractive features of the PCR approach are the ease and speed with which large numbers of specimens can be tested. PCR mycoplasma analysis provides a readily available, quick and reliable test system with which to manage the important issue of mycoplasma contamination of cell lines.
Leukemia 2002 Feb
PMID:Detection of mycoplasma in leukemia-lymphoma cell lines using polymerase chain reaction. 1184 Feb 97

Mammalian cell-expressed therapeutic proteins are particularly vulnerable to contamination by endogenous retrovirus-like particles (RVLPs). The Viresolve NFR filter was designed to meet the critical requirement of manufacturing a safe and virus-free therapeutic by retaining RVLPs by a minimum of six log reduction value (LRV). The NFR designation refers to retrovirus removal in a normal flow format. To qualify the product, we tested two model viruses: the 78 nm diameter phi6 bacteriophage and the 80-110 nm diameter Xenotropic Murine Leukemia Virus (X-MuLV). Robust retention was demonstrated over a wide range of process parameters. Viresolve NFR filters also retain other model adventitious viruses including 70-85 nm diameter Reovirus 3 (Reo3), 70-90 nm diameter Adenovirus 2 (Ad2), and 53 nm diameter PR772 by >6 LRV. In addition to these model viruses, the filter retains >7 LRV of both the mycoplasma Acholeplasma laidlawii and the bacterium Brevundimonas diminuta. Protein passage is shown to be consistently high (95-100%) for a variety of therapeutic protein products, including monoclonal antibodies. Characterization of the filter in specific applications is made simple by availability of ultralow surface area (5 cm(2)) disks, which are shown to scale linearly to the manufacturing scale pleated-filters. Viresolve NFR filters provide consistent water permeability performance (34-37 LMH/psi) and show very little plugging for all feedstocks evaluated. The Viresolve NFR filter incorporates Retropore, a unique asymmetric polyethersulfone membrane, the surface of which has been modified to minimize protein binding.
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PMID:Performance of a novel Viresolve NFR virus filter. 1215 13

Priapism is a rare urologic emergency in pediatric population. It is usually a consequence of sickle cell disease. Leukemia is another important cause of priapism in children. We present a case of priapism associated with an acute pulmonary infection. To our knowledge, this is the second case describing this association. In the other reported case, pulmonary infection was related to Mycoplasma Pneumoniae. The hypothesis is that infection with Mycoplasma Pneumoniae can produce a hypercoagulable state, especially in selected areas of the circulation.
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PMID:[Pediatric priapism associated with pulmonary infection]. 1287 8

Hummeler, Klaus (The Children's Hospital of Philadelphia, Philadelphia, Pa.), Natale Tomassini, and Leonard Hayflick. Ultrastructure of a mycoplasma (Negroni) isolated from human leukemia. J. Bacteriol. 90:517-523. 1965.-A strain of mycoplasma isolated in tissue cultures from human leukemic bone marrow was cultivated in cell-free media for 23 passages. Concentrates of broth cultures were investigated under the electron microscope in thin sections and negative contrast. The ultrastructure of the mature mycoplasma cells and their elementary bodies is described. It was found that the elementary bodies, particularly in the negative contrast preparations, bear a close resemblance to viruslike particles seen in tissues and plasmas of leukemic patients.
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PMID:ULTRASTRUCTURE OF A MYCOPLASMA (NEGRONI) ISOLATED FROM HUMAN LEUKEMIA. 1432 68

A case-control study was nested within two maternity cohorts with a total of 7 million years of follow-up for assessment of the role of bacterial infections in childhood leukemia. Offspring of 550,000 mothers in Finland and Iceland were combined to form a joint cohort that was followed for cancer up to age 15 years during 1975-1997 through national cancer registries. For each index mother-case pair, three or four matched control mother-control pairs were identified from population registers. First-trimester serum samples were retrieved from mothers of 341 acute lymphoblastic leukemia cases and 61 other leukemia cases and from 1,212 control mothers. Sera were tested for antibodies to the genus Chlamydia, Helicobacter pylori, and Mycoplasma pneumoniae. Odds ratios and 95% confidence intervals, adjusted for sibship size, were calculated as estimates of relative risk. M. pneumoniae immunoglobulin M appeared to be associated with increased risk (odds ratio (OR) = 1.6), but the association lost statistical significance when the specificity of the immunoglobulin M was considered (OR = 1.5, 95% confidence interval: 0.9, 2.4). In Iceland, H. pylori immunoglobulin G was associated with increased risk of childhood leukemia in offspring (OR = 2.8, 95% confidence interval: 1.1, 6.9). Since H. pylori immunoglobulin G indicates chronic carriage of the microorganism, early colonization of the offspring probably differs between Iceland and Finland, two affluent countries.
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PMID:Associations between three types of maternal bacterial infection and risk of leukemia in the offspring. 1612 Jul 7

Recently, a third novel feline hemotropic Mycoplasma sp. (aka hemoplasma), "Candidatus Mycoplasma turicensis," in a cat with hemolytic anemia has been described. This is the first study to investigate the prevalence, clinical manifestations, and risk factors for all three feline hemoplasma infections in a sample of 713 healthy and ill Swiss cats using newly designed quantitative real-time PCR assays. "Candidatus Mycoplasma haemominutum" infection was detected in 7.0% and 8.7% and Mycoplasma haemofelis was detected in 2.3% and 0.2% of healthy and ill cats, respectively. "Candidatus Mycoplasma turicensis" was only detected in six ill cats (1.1%); three of them were coinfected with "Candidatus Mycoplasma haemominutum." The 16S rRNA gene sequence of 12 Swiss hemoplasma isolates revealed >98% similarity with previously published sequences. Hemoplasma infection was associated with male gender, outdoor access, and old age but not with retrovirus infection and was more frequent in certain areas of Switzerland. "Candidatus Mycoplasma haemominutum"-infected ill cats were more frequently diagnosed with renal insufficiency and exhibited higher renal blood parameters than uninfected ill cats. No correlation between hemoplasma load and packed cell volume was found, although several hemoplasma-infected cats, some coinfected with feline immunodeficiency virus or feline leukemia virus, showed hemolytic anemia. High M. haemofelis loads (>9 x 10(5) copies/ml blood) seem to lead to anemia in acutely infected cats but not in recovered long-term carriers. A repeated evaluation of 17 cats documented that the infection was acquired in one case by blood transfusion and that there were important differences among species regarding whether or not antibiotic administration led to the resolution of bacteremia.
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PMID:Prevalence, risk factor analysis, and follow-up of infections caused by three feline hemoplasma species in cats in Switzerland. 1651 84

Mycoplasma can establish latent infections and are associated with arthritis, leukemia, and chronic lung disease. We developed an experimental model in which lung cells are deliberately infected with Mycoplasma fermentans. Human lung fibroblasts (HLF) were exposed to live M. fermentans and immune-modulating cytokine release was assessed with and without known inducers of cytokine production. M. fermentans increased IL-6, IL-8/CXCL8, MCP-1/CCL2, and Gro-alpha/CXCL1 production. M. fermentans interacted with TNF-beta to release more IL-6, CXCL8, and CXCL1 than predicted by the responses to either stimulus alone. The effects of live infection were recapitulated by exposure to M. fermentans-derived macrophage-activating lipopeptide-2 (MALP-2), a Toll-like receptor-2- and receptor-6-specific ligand. The synergistic effect of combined stimuli was more pronounced with prolonged incubations. Preexposure to TNF-beta sensitized the cells to subsequent MALP-2 challenge, but preexposure to MALP-2 did not alter the IL-6 response to TNF-beta. Exposure to M. fermentans or MALP-2 did not enhance nuclear localization, DNA binding, or transcriptional activity of NF-kappaB and did not modulate early NF-kappaB activation in response to TNF-beta. Application of specific inhibitors of various MAPKs suggested that p38 and JNK/stress-activated protein kinase were involved in early IL-6 release after exposure to TNF-beta and M. fermentans, respectively. The combined response to M. fermentans and TNF-beta, however, was uniquely sensitive to delayed application of SP-600125, suggesting that JNK/stress-activated protein kinase contributes to the amplification of IL-6 release. Thus M. fermentans interacts with stimuli such as TNF-beta to amplify lung cell production of immune-modulating cytokines. The mechanisms accounting for this interaction can now be dissected with the use of this in vitro model.
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PMID:Mycoplasma fermentans and TNF-beta interact to amplify immune-modulating cytokines in human lung fibroblasts. 1675 Dec 26


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