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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In Burkitt's lymphoma, dental structures may provide the route for Epstein-Barr virus (EBV) in saliva to penetrate the jaws, thereby promoting tumor formation. In children, EBV could enter tooth sockets exposed following deciduous tooth loss and thereby contact jaw marrow lymphocytes stimulating neoplastic transformation. Marrow contact by EBV probably also occurs through carious teeth. Jaw tumors are rare in adults because their jaw marrow is no longer hematopoietic and so lacks the lymphoid substrate for the virus. In adults, jaw marrow lymphocytosis, as accompanies infectious mononucleosis and perhaps malaria, or which could develop around the roots of carious teeth having chronic periapical infection, could provide the substrate for EBV. EBV could then contact the jaw marrow lymphocytes when teeth are extracted and so favor jaw tumor development. Therefore, prevention of dental caries might reduce jaw tumor prevalence in Burkitt's lymphoma except among children ages 6-13 whose jaw marrow would unavoidably become infected by salivary EBV when the latter is present at the time of deciduous tooth loss.
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PMID:Circumstances favoring jaw tumors in Burkitt's lymphoma. 632 20

Supernatants obtained from the in vitro culture of Plasmodium falciparum infected erythrocytes induced prolonged lymphocyte survival in culture for more than 8 weeks in six cultures and permanent cell lines were established in four of these. The cells in the latter showed lymphoblastoid features similar to those seen in parallel cultures to which transforming Epstein-Barr (EB) virus instead of P. falciparum derived substances had been added. Cells from the same donors stimulated with other mitogens (pokeweed mitogen, Salmonella paratyphi culture supernatants) ceased to proliferate and died after 3-4 weeks. A 195 Kd polypeptide obtained from P. falciparum parasites also exhibited the potential to transform normal lymphocytes. Characterization of the cell lines indicated a B lymphocyte origin and the presence of EB virus in these lines suggests the possibility that P. falciparum products may activate latent EB virus genomes. These observations appear relevant to both the choice of P. falciparum derived antigens as vaccines, and to the interaction of EB virus and malaria in the aetiology of African Burkitt's lymphoma (BL).
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PMID:Plasmodium falciparum products enhance human lymphocyte transformation by Epstein-Barr virus. 632 64

The frequency of Burkitt's lymphoma peaks in children six to nine years of age and is twice as high in males as in females. To determine if age or sex had any relationship to outcome of therapy, the authors examined the experience of 387 patients treated for Burkitt's lymphoma at the Burkitt Tumor Project, Accra, Ghana, between 1966 and 1978. No age or sex relationship could be demonstrated with overall survival. However, among children without central nervous system disease who achieved an initial remission, the relapse rates were higher for those diagnosed initially in the age interval 6-9 years than for those diagnosed at younger or older ages. This pattern was seen for each stage of the disease as well as overall. Sex did not influence relapse rate. The relationship of these findings to the Epstein-Barr virus and malaria, both suspected factors in the etiology of this disease, is discussed, but neither appears to explain our results.
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PMID:Age and sex as factors influencing remission duration in African Burkitt's lymphoma. 713 53

In this study the presence of Epstein-Barr virus (EBV) carrying B lymphocytes in different B-cell subpopulations from peripheral blood was determined by spontaneous outgrowth which gives rise to lymphoblastoid cell lines. In healthy seropositive adults, the EBV-carrying B cell was predominantly within the IgM- and IgD-positive but not the IgG-positive subpopulations. Furthermore, these B lymphocytes were in the low-density (large cell) Percoll fraction. The IgM- and IgD-positive B cell phenotype suggests the EBV-carrying B cells to be circulating virgin B cells recently released from the bone marrow. These B cells have an estimated life span of only 6-8 weeks suggesting that long-term EBV persistence in the body may be the result of infection of a more primitive B-cell type. Similar experiments were carried out in children with acute malaria from the Gambia, West Africa, where Burkitt lymphoma (BL) is endemic in order to determine whether a population of EBV-carrying B cells could be identified which had a similar phenotype to the BL cell. The EBV-carrying B cells in this patient group were also found in the IgM-positive, IgG-negative B-cell subpopulation. The majority of these cells were found in the low-density (large cell) Percoll fraction although in some patients a proportion was derived from the high-density (small cell) fraction. This cellular phenotype is not representative of a BL cell.
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PMID:Epstein-Barr virus-carrying B cells are large, surface IgM, IgD-bearing cells in normal individuals and acute malaria patients. 795 72

The etiology of Burkitt's lymphoma (BL) includes three factors which operate in a stepwise fashion: (1) the ubiquitous Epstein-Barr virus (EBV) which possesses oncogenic potential when it infects infants or very young children; (2) malaria which specifically depresses cytotoxic T cell clones controlling the polyclonal proliferation of EBV-infected B cells in the host; and (3) chromosomal translocations activating the c-myc oncogene which in turn induces uncontrolled B cell proliferation. The unravelling of such a multistep carcinogenic process has shaken a number of well-established dogmas of our time.
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PMID:The etiology of Burkitt's lymphoma and the history of the shaken dogmas. 801 47

At least three genetic changes are known to contribute to the genesis of Burkitt's lymphoma (BL): the Ig/myc translocation, the presence of Epstein-Barr virus (EBV) in the vast majority of the endemic and a minority of sporadic tumors, and a p53 mutation, present in approximately 60% of the BL-derived lines. Activation of c-myc by juxtaposition to Ig sequences is a universal common denominator in endemic and sporadic EBV positive and negative BLs. It acts by preventing the cell from leaving the cycling compartment and by facilitating immune escape. EBV probably acts by expanding the target cell population at risk and prolonging its life span. This, together with the malaria co-factor, would increase the risk of the translocation accident. The p53 mutation may be essential for the continued growth of the tumors where it occurs, since introduction of wild-type p53 leads to their apoptotic death.
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PMID:Multistep evolution of B-cell-derived tumors in humans and rodents. 827 58

Epstein-Barr virus (EBV) type 2 is considered to be a much less potent transformer of lymphocytes than type 1. However, type-2 EBV may be involved in the pathogenesis of non-Hodgkin's lymphomas (NHLs) arising in immunocompromised patients, i.e., subjects with malaria or HIV-1 infection. To determine whether type-2 EBV may also play a role in Hodgkin's disease (HD) developing in immunocompromised patients, we characterized EBV subtypes in EBV-positive HD samples from 10 HIV-1-positive patients as well as from a control population of 24 HIV-1-negative patients. Type-2 EBV was detected in 5/10 HD samples from the HIV-1-positive group (1 case showed concomitant type-1 EBV positivity), but only in 1/20 HD samples from the HIV-1-negative group, indicating that, during HIV-1-induced immunodepression, type-2 EBV may be pathogenetically involved also in HD, as previously reported for HIV-associated NHLs.
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PMID:Subtypes of Epstein-Barr virus in HIV-1-associated and HIV-1-unrelated Hodgkin's disease cases. 839 80

The Epstein-Barr Virus (EBV) is consistently found in tumor cells of Burkitt's lymphoma (BL) endemic in central Africa and malaria is considered a pathogenic cofactor. In contrast, fewer than 20% of BL cases occurring in Western countries are EBV-associated. We have investigated 54 BL cases from Bahia, a tropical region of Northeast Brazil, for expression of EBV gene products by in situ hybridization and immunohistology and performed typing of the EBV by polymerase chain reaction. Ten pediatric BL cases from Germany served as controls. New cases of malaria were not observed in the period and area of our study. Small nuclear EBV encoded transcripts, EBER, were found in tumor cells of 47 of 54 Brazilian cases (87%) but in only 2 of 10 German cases (20%). Type I latency of the EBV infection with absence of EBV-encoded proteins LMP1 and EBNA2 was found in 45 of 47 of the EBER-positive Brazilian cases. In two cases, occasional LMP1-containing tumor cells were found in the neighborhood of small Schistosoma mansoni granulomas and scars. BHLF1 transcripts associated with lytic EBV infection could be detected in few cells in 3 of the 40 EBER-positive Brazilian cases investigated. EBV type A was found in the majority of Brazilian BL cases (20 of 30 A-type, 7 of 30 B-type, and 3 of 30 not amplifiable). Our results indicate that the association of Bahian BL with EBV, but not the regional prevalence of malaria, is similar to endemic African BL. In two cases, type II latency was found in association with schistosomiasis, suggesting a role of this parasitosis in the induction of an EBV expression pattern that is unusual for BL. Because chronic schistosomiasis is associated with elevated Th2 cytokine expression resulting in reduced cell-mediated cytotoxicity, it seems possible that altered local immunity is responsible for this peculiar phenotype.
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PMID:Expression of Epstein-Barr virus-gene products in Burkitt's lymphoma in Northeast Brazil. 973 Oct 79

Epstein-Barr virus (EBV) has been linked to several undifferentiated carcinomas of the aerodigestive tract, especially the nasopharynx, but has not been reported in the biliary tract. We here presented a case of an unusual cholangiocarcinoma harboring EBV genome in a 47-year-old Chinese woman. Physical examination in 1988 in Taiwan, including abdominal sonography of the liver, was essentially negative. She experienced three episodes of malaria in 1990 when she worked in Ghana, Africa, and felt a tumor mass in the epigastrium in October 1992. She received an extended left lobectomy for a huge hepatic tumor of 12 x 10 x 5.5 cm in February 1993. Light microscopy revealed a cholangiocarcinoma composed of both well-differentiated adenocarcinoma and lymphoepitheliomatous undifferentiated carcinoma components. Abundant EBV EBER1 was shown in both tumor components, but not in the nontumor liver. Southern blot analysis and polymerase chain reaction showed a monoclonal episomal form of EBV, with a genotype characteristic for Chinese EBV strain type 1. This finding suggests that the EBV infection preceded monoclonal EBV-harboring tumor cell expansion in this case.
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PMID:Clonal Epstein-Barr virus associated cholangiocarcinoma with lymphoepithelioma-like component. 876 21

The Epstein-Barr virus (EBV) is an ubiquitous virus infecting nearly the entire adult human population. The EBV is closely associated with rhinopharyngeal cancer in Southern China and Northern Africa. Three geographic subtypes of EBV have been identified to date. They differ by their nuclear antigene EBNA2. The EBNA2 AC strains predominate in Asia; EBNA2 AD strains predominate in the United States; EBNA2 B strains have all been identified in black Africa. Burkitt's lymphoma is the most frequent tumor in children aged 5 to 9 years in equatorial Africa. A prospective study in 42,000 children in Ouganda demonstrated that children who develop Burkitt's lymphoma have severe EBV infection during the first months of life. Very early EBV infection observed in North or equatorial Africa increases the risk of Burkitt's lymphoma by 20-times that in Europe. Hyperendemic malaria observed in the equatorial zone increases the incidence of tumors by a factor of 20. An association between EBV and rhinopharyngeal cancer is a constant feature only in South China, in North and East Africa, as well as in arctic regions as cases of carcinoma not associated with EBV infection have been reported in Greece. Surveys in the Democratic Republic of China concerning several hundred thousand persons have shown that serum IgA/VCA allows early diagnosis of cancer. It is estimated that the risk of rhinopharyngeal cancer is 20% in Chinese with high levels of IgA/VCA.
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PMID:[Epstein-Barr virus and associated diseases. Course of Medical Virology, Institut Pasteur, 1995/1996]. 953 9


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