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K Bhatia

Publications and source records attributed to K Bhatia.

At least 37 records · Page 2Linked to original sources
PubMed2001

Expression of EBV encoded nuclear small non-polyadenylated RNA (EBER) molecules in 32 cases of childhood Burkitt's lymphoma from Israel.

We have analyzed paraffin sections from 32 children with histologically confirmed Burkitt's Lymphoma (BL) for the presence of EBV using in situ hybridization to detect expression of the EBV-encoded early RNAs (EBERs). EBV was present in the tumors of 11 patients (34%). Sixty nine percent of the children presented with abdominal disease, 19% had bone marrow infiltration and only one child had jaw involvement. There was no statistically significant difference between EBV positive and EBV negative children with regard to age, gender, origin, primary site at presentation, or clinical stage of disease. However, there was a trend for younger age in the children with EBV positive BL with a median age of 4, compared to 7 years in children with EBV negative BL. None of the 7 children of Ashkenazi Jewish origin had EBER positive disease. There was no difference in the treatment outcome between the EBV positive patients (estimated survival at 24 months of 82%) and EBV negative children (estimated survival rate of 71% (p=0.58)). In conclusion, although this is only a small series it seems that childhood BL in Israel has the clinical characteristics of sporadic, non-African type with 34% EBV association and a low incidence of jaw tumors. Our data suggest that Ashkenazi Jewish children with BL are less likely to have EBV positive tumors than other ethnic groups. However, more patients will need to be studied in order to assess the validity of this observation.

Abdominal Neoplasms↗
PubMed2000

Mutation of BAX occurs infrequently in acquired immunodeficiency syndrome-related non-Hodgkin's lymphomas.

Acquired immunodeficiency syndrome (AIDS)-related non-Hodgkin's lymphomas (AIDS-NHLs) consistently derive from B cells, are histologically heterogeneous, and are associated with distinct molecular pathways depending upon histology. Recently, it has been proposed that inactivating mutations of the bax death agonist may contribute to the pathogenesis of human tumors. In particular, among B-cell malignancies, BAX mutations have been detected at a certain frequency in Burkitt lymphomas. This study is aimed at defining the status of the BAX gene throughout the clinicopathologic spectrum of AIDS-NHL (n = 54), including AIDS-related Burkitt lymphoma (n = 14), AIDS-related Burkitt-like lymphoma (n = 8), AIDS-related diffuse large cell lymphoma (n = 15), AIDS-related primary central nervous system lymphoma (n = 6), and AIDS-related primary effusion lymphoma (n = 11). All 6 BAX exons and flanking sequences were subjected to mutational analysis by polymerase chain reaction-single strand conformation polymorphism followed by DNA direct sequencing of positive cases. Mutations of BAX among AIDS-NHL were restricted to a cell line of AIDS-related primary effusion lymphoma, which harbored a frameshift mutation causing the introduction of a proximal stop codon. All other AIDS-NHL displayed wild-type BAX alleles. In order to investigate whether BAX inactivation in AIDS-NHL may occur through mechanisms other than gene mutation, bax protein expression was investigated by Western blot analysis or immunohistochemistry in selected cases. All AIDS-NHL analyzed expressed normal bax proteins. Overall, this study indicates that deregulation of apoptotic control in AIDS-NHL is not caused by BAX alterations. Genes Chromosomes Cancer 27:177-182, 2000.

Blotting, Western↗
PubMed2000

Pattern of immunoglobulin (Ig) and T-cell receptor (TCR) gene rearrangements in childhood acute lymphoblastic leukemia in India.

In 120 cases of acute lymphoblastic leukemia (median age 8 years), IgH chain gene was rearranged in 99% B-Cell Precursor (BCP) ALLs and 13% T-ALLs. One or the other TCR locus was rearranged not only in all T-ALLs, but also in 87% of BCP-ALLs. TCR-beta rearrangement in BCP-ALL was associated with a higher mean age at presentation (8.7 vs. 6.2 years, P=0.008), lower mean platelet counts (61.2x10(9)/l vs. 103.7x10(9)/l, P=0.003) and a poorer DFS (% cummulative survival 0 vs. 88.9+/-10.5, P=0.004). TCR-gamma rearrangement in T-ALL was associated with a higher mean WBC count (186.3x10(9)/l vs. 63. 4x10(9)/l, P=0.002). Also, the pattern of rearrangement of these genes appeared to be different from the West; viz. TCR-beta rearrangement in a higher proportion of BCP-ALLs (58%, 95% confidence intervals 45-69%), invariable deletion of Cgamma1 and only monoallelic rearrangement for TCR-delta locus. This repertoire of gene rearrangement may have a bearing on the poor treatment outcome reported previously from our geographic region.

Adolescent↗
PubMed2000

Epstein-Barr virus association in classical Hodgkin's disease provides survival advantage to patients and correlates with higher expression of proliferation markers in Reed-Sternberg cells.

BACKGROUND: Most Epstein-Barr virus (EBV) associated lymphoproliferative disorders have high proliferation indices. However, classical Hodgkin's disease (cHD) is heterogeneous, with respect to proliferation index of the Reed-Sternberg cell (RS cell), and EBV association. Hence, we investigated whether cHD with and without EBV-association differ with respect to the proliferation index of the RS cells. Further we investigated whether this would have a bearing on patients survival. PATIENTS AND METHODS: We investigated 110 cases of cHD for: a) EBV association by immunohistochemical demonstration of EBV-latent membrane protein-1 and EBV encoded nuclear RNA 1 by mRNA in situ hybridisation; b) Proliferating cell nuclear antigen (PCNA) expression in the RS cells. RESULTS: EBV association was noted in 86 of 110 cases (78%). Higher PCNA expression (P = 0.004) and younger age (P = 0.001) correlated independently with EBV association. The 10 year relapse free survival (RFS) of EBV+ and EBV- patients were 60% and 44%, respectively (P = 0.03). The 10 year overall survival (OS) of EBV+ and EBV- patients were 85% and 64%, respectively (P = 0.03). EBV association maintained its significant impact on RFS and OS within Cox proportional hazard model. CONCLUSIONS: Our study suggests that EBV is likely to confer a higher PCNA expression and also contribute towards maintaining the RS cells of cHD in cell cycle. Hence, RS cells in EBV associated cHD would be more responsive to chemotherapy and radiotherapy associated DNA damage. Thus, EBV-association provides survival advantage to cHD patients treated with standard chemotherapy and radiotherapy protocols.

Adolescent↗
PubMed2000

Discrepancies in Epstein-Barr virus association at presentation and relapse of classical Hodgkin's disease: impact on pathogenesis.

BACKGROUND: Though Epstein-Barr virus (EBV) has been linked to classical Hodgkin's disease (cHD), only a proportion of cHD cases show EBV-association. While there has been evidence to suggest a crucial role for EBV in the early phase of cHD evolution, we are unclear whether continued presence of EBV is essential for the maintenance of the neoplasm. We have addressed this issue by investigating the EBV-association in paired samples of cHD obtained at presentation and relapse. MATERIALS AND METHODS: We have analysed lymph node biopsy samples from 23 cases of cHD at presentation and relapse. In situ hybridization with EBER-1 probe and immunostaining with anti latent membrane protein-1 (LMP-1) antibody was performed on the paraffin sections. PCR for EBNA 3C gene was performed for EBV subtype analysis on the DNA extracted from paraffin sections. RESULTS: EBV-association was documented in both the presentation and relapse samples of 14 cases. One case showed loss of EBV-association at relapse. PCR analysable DNA was obtained from both presentation and relapse samples in four of the EBV-associated cases. The EBNA 3C amplimer corresponded to type A strain of EBV in all the samples. CONCLUSION: Loss of EBV-association between presentation and relapse seen in one case implies a hit and run mechanism in EBV-induced lymphomagenesis. Though EBV may be essential early in the evolution of cHD, it may not be required for maintenance of the neoplastic clone. Our study also brings out a speculation that a proportion of EBV-negative cHD could represent loss of EBV in the tumour prior to clinical presentation. Alternatively, an unidentified lymphotropic virus other than EBV might play a pathogenetic role in EBV-negative cHD.

Burkitt Lymphoma↗
PubMed2000

Molecular profile of Epstein-Barr virus infection in HHV-8-positive primary effusion lymphoma.

Primary effusion lymphoma (PEL) selectively involves the serous body cavities, occurs predominantly in immunodeficient patients and is infected consistently by human herpesvirus type-8. PEL is also frequently infected by Epstein-Barr virus (EBV). The precise pathogenetic role of EBV coinfection in PEL is not fully understood. The lymphoma fails to express the EBV transforming proteins EBNA-2 and LMP-1, whereas it expresses EBNA-1 (latency I phenotype). Some studies have hypothesized that other EBV-positive lymphomas expressing the latency I phenotype may associate with specific molecular variants of EBNA-1, although this issue has not been addressed in PEL. On this basis, this study is aimed at a detailed molecular characterization of EBV in PEL. Fifteen EBV positive PEL (12 AIDS-related, one post-transplant, two arising in immunocompetent hosts) were subjected to molecular characterization of the viral genes EBNA-1 and LMP-1, as well as definition of EBV type-1/type-2. The EBNA-1 gene displayed a high degree of heterogeneity in different cases of PEL, with seven distinct recognizable variants and subvariants. A wild-type LMP-1 gene was detected in 10/15 cases, whereas in 5/15 cases the LMP-1 gene harbored a deletion spanning codons 346-355. EBV type-1 occurred in 11/15 PEL whereas EBV type-2 occurred in 4/15 cases. Despite a high degree of genetic variability of the virus in different PEL cases, each single PEL harbored only one EBV variant, consistent with monoclonality of infection and suggesting that infection preceded clonal expansion. Overall, our results indicate that: (1) individual PEL cases consistently harbor a single EBV strain; (2) EBNA-1 displays a high degree of heterogeneity in different PEL cases; (3) no specific EBV genotype preferentially associates with PEL.

DNA, Viral↗
PubMed2000

Pattern of premature degenerative changes of the cervical spine in patients with spasmodic torticollis and the impact on the outcome of selective peripheral denervation.

OBJECTIVES: To characterise the pattern of and risk factors for degenerative changes of the cervical spine in patients with spasmodic torticollis and to assess whether these changes affect outcome after selective peripheral denervation. METHODS: Preoperative CT of the upper cervical spine of 34 patients with spasmodic torticollis referred for surgery were reviewed by two radiologists blinded to the clinical findings. Degenerative changes were assessed for each joint separately and rated as absent, minimal, moderate, or severe. Patients were clinically assessed before surgery and 3 months postoperatively by an independent examiner using standardised clinical rating scales. For comparison of means a t test was carried out. To determine whether an association exists between the side of degenerative changes and type of spasmodic torticollis a chi(2) test was used. Changes in severity, disability, and pain before and after surgery were calculated using a Wilcoxon matched pairs signed ranks test. RESULTS: Fourteen out of 34 patients had moderate or severe degenerative changes. They were predominantly found at the C2/C3 and C3/C4 level and were significantly more likely to occur on the side of the main direction of the spasmodic torticollis (p = 0.015). There was no significant difference in age, sex, duration of torticollis, overall severity, degree of disability, or pain between the group with either no or minimal changes and the group with moderate or severe changes. However, in the second group the duration of inadequate treatment was longer (10.1 v 4.8 years; p=0.009), head mobility was more restricted (p = 0.015), and head tremor was more severe (p = 0.01). At 3 months postoperatively, patients with n or minimal degenerative changes showed a significant improvement in pain and severity whereas no difference was found in those with moderate or severe changes. CONCLUSIONS: Patients with spasmodic torticollis have an increased risk of developing premature degenerative changes of the upper cervical spine that tend to be on the side towards which the head is turned or tilted and compromise outcome after surgery. Effective early treatment of spasmodic torticollis with botulinum toxin seems to have a protective effect. Patients with spasmodic torticollis and restricted head mobility who do not adequately respond to treatment should undergo imaging of the upper cervical spine. Patients with imaging evidence of moderate or severe degenerative changes seem to respond poorly to selective peripheral denervation.

Adult↗
PubMed2000

Association of Burkitt's lymphoma with the Epstein-Barr virus in two developing countries.

The clinical presentation of Burkitt's lymphoma (BL) and it's association with the Epstein-Barr virus (EBV) varies in different geographic areas, BL in developing countries being "intermediate" between the sporadic and endemic types, both in it's clinical presentation and it's association with EBV, which varies from 25-80%. In this study we have analysed the clinical features, EBV association, subtype and prevalence of the deleted variant of the Latent Membrane Protein-1 (LMP-1) of EBV in forty-two cases from two developing countries- India (n = 25) and Argentina (n = 17). In both countries the abdomen was the site most commonly involved while jaw involvement was rare. EBV was detected by in-situ hybridization using the EBER-1 RNA probe. 47% of cases from Argentina and 80% of cases from India were EBER positive. EBV typing using EBNA-3C primers showed a predominance of Type A in both countries (India-13/16 and Argentina-(7/8)). The 30bp deletion of the LMP-1 gene was detected in all evaluated cases from Argentina while the wild type of the gene was seen in all the evaluable Indian cases. Our study highlights the similarities and differences in the clinical presentation and EBV association of BL in two developing countries and also indicates that the subtype of EBV and prevalence of the LMP-1 deletion may reflect the predominant subtype in a particular population.

Adolescent↗
PubMed2000

Association of EBV strains, defined by multiple loci analyses, in non-Hodgkin lymphomas and reactive tissues from HIV positive and HIV negative patients.

Epstein-Barr virus (EBV) associated with lymphoid neoplasms demonstrates preferential association with certain viral strains. Previous subtyping studies have however been confined to analysis of sequence variability within a single locus in EBV. Variations have now been reported for several latently expressed EBV genes, including, EBNAs-1, 2 and LMP-1. Variant EBNA-1 strains have been identified in Burkitt's lymphomas and clustering of subtypes for LMP and EBNA-2 have been associated with either malignancy and/or clinical disease. To investigate the linkage between the variability in these three loci in EBV associated with lymphoid malignancies, we subclassified EBV-associated lymphoproliferations (9 reactive and 24 malignant) from HIV-negative and HIV-positive patients by analysis of the EBNA-1, LMP1, and EBNA-2 genes. Our results demonstrate that (1) EBV identical to the prototype B95.8 strain (Type 1 EBNA-2, wild type EBNA-1 and LMP-1) is very rarely associated with tumors. (2) The EBNA-1 variant V-leucine, restricted to malignant lymphomas in immunocompetent patients, was readily identified in non-malignant lesions in HIV infected patients. (3) Variations of EBNA-1 occur independent of variations at other loci.

Antigens, Viral↗
PubMed1999

Bax is frequently compromised in Burkitt's lymphomas with irreversible resistance to Fas-induced apoptosis.

We have analyzed the Fas-mediated death pathway in a panel of 11 Epstein-Barr virus (EBV)-negative and 10 EBV-positive Burkitt's lymphoma (BL) cell lines. We show that the increased expression of Fas in EBV-positive cell lines is mediated via LMP-1. Four of the 21 BL cell lines are readily responsive to Fas-mediated cell death signals. Of the remaining 17 cell lines, 10 can be sensitized by up-regulating Fas either via exogenous expression of LMP-1 or via treatment with CD40L. These same cell lines can also be sensitized by treatment with cycloheximide (CHX), which, however, does not result in up-regulation of Fas. Neither up-regulation of Fas, nor treatment with CHX, restore Fas sensitivity in seven BL cell lines. Further analyses indicated that 5 of the 7 cell lines (and none of the 14 responsive cell lines) were also compromised in the integrity/expression of the proapoptotic gene Bax. Thus, in most BL cell lines, the Fas pathway seems to be inhibited, although the mechanism of inhibition varies. The correlation between Bax mutation and irreversible (by CD40L or CHX) Fas resistance raises the possibility, for the first time, that Bax may play a critical function in Fas-mediated cell death in BL.

Animals↗
PubMed1999

Histological and immunophenotypic profile of nasal NK/T cell lymphomas from Peru: high prevalence of p53 overexpression.

Nasal NK/T-cell lymphoma is a unique form of lymphoma highly associated with Epstein-Barr virus (EBV). These lymphomas are rare in Western populations and much more prevalent in some Asian and Latin American countries. Although there are several sizable studies from Asian countries, the same is not true from South America. The aim of this study was to analyze a series of 32 cases of nasal T-cell lymphoma from Peru and to further extend the characterization of this disease. Immunohistochemistry was performed on paraffin sections using the following antibodies: CD20 (L26), CD45RO, CD3, Ki67, CD57, CD56, TIA-1, bcl-2, and p53. The presence of EBV was investigated with immunohistochemical analysis for latent membrane protein (LMP)-1 and in situ hybridization using an antisense riboprobe to EBER 1. The 32 patients included 18 men and 14 women (M:F ratio, 1.2:1), with a median age of 43 years (11 to 72). Three categories were identified: (1) Nasal NK/T cell lymphomas (28 cases): The morphology ranged from small or medium-sized cells to large transformed cells. Necrosis was present in 86% of the cases, and angioinvasion was seen in 36% of the cases. All cases were positive for CD45RO, CD3, and for TIA-1. CD56 was positive in 21 of 27 cases (78%), and CD57 was negative in all cases. EBER 1 positivity was identified in most of the tumor cells in 27 of 28 cases (96%), including the six cases in which CD56 was negative. Overexpression of p53 was detected in 24 cases (86%). (2) Blastic NK cell lymphoma (1 case): The neoplastic cells resembled those of lymphoblastic lymphoma. CD56 and CD45RO were positive; TIA-1, TdT, and EBER-1 were negative. (3) Peripheral T-cell lymphoma (PTCL) unspecified (3 cases): CD56, TIA-1, and EBER-1 were negative. Nasal lymphomas from Peru with a T cell phenotype are predominantly EBV-associated NK/T cell lymphomas, similar to those described in Asian countries. The expression of CD56, TIA-1, and EBER-1, in combination, are very useful markers for the diagnosis of nasal NK/T cell lymphoma in paraffin-embedded tissue. The differential diagnosis of T-cell lymphomas in the nasal region should include rare cases of PTCL unspecified and the blastic variant of NK cell lymphoma. P53 is overexpressed in 86% of the cases. The significance of this finding with regard to clinical behavior and prognosis remains to be determined.

Adolescent↗
PubMed1999

Development of EBV-positive T-cell lymphoma following infection of peripheral blood T cells with EBV.

Chronic active Epstein-Barr virus (EBV) infection is manifested clinically by the persistence of infectious mononucleosis-like symptoms or its complications for a prolonged period ranging from one to several years. This syndrome may include severe disease manifestations and can be fatal. The role of EBV in the pathogenesis of chronic active EBV infection has been unclear. We investigated two Japanese patients with severe chronic active EBV infection who subsequently developed EBV-positive T-cell lymphoma. We found that the patients had evidence of EBV infection in the peripheral blood CD4+ T-cells 19 and 3 months, respectively, before the T-cell lymphoma was diagnosed. The lymphomas were infected with monoclonal EBV and expressed the EBV latency genes EBNA-1, LMP-1, and LMP-2A, a virus latency pattern referred to as latency II. Genetic studies showed that the virus detected in the T-cell lymphoma was indistinguishable from the virus in the peripheral blood CD4+ T-cells. These studies support an important pathogenetic role of T-cell infection with EBV in chronic active EBV infection and in the EBV-positive T-cell lymphoma that followed.

Antigens, CD↗
PubMed1998

Prolongation of the p53 response to DNA strand breaks in cells depleted of PARP by antisense RNA expression.

The observation that 3-aminobenzamide, which inhibits a variety of ADP-ribose transferases, prolongs the gamma-irradiation-induced increase in intracellular p53 concentration suggested that one or more of such enzymes may determine the duration of the p53 response during G1 arrest. The role of poly(ADP-ribose) polymerase (PARP), an abundant nuclear enzyme activated by DNA strand breaks, in the p53 response to y-irradiation was investigated in Burkitt's lymphoma AG876 cells stably transfected with an inducible PARP antisense construct. Immunoblot analysis revealed that the cellular content of PARP was reduced to virtually undetectable levels after incubation of transfected cells for 72 h with the inducer dexamethasone. In noninduced antisense cells, the p53 concentration reached a maximum 2 h after exposure to 6.3 Gy of gamma-radiation and returned to control values by 4 h. In contrast, the p53 response in PARP-depleted antisense cells peaked at 4 h, with the levels of p53 remaining elevated for up to 12 h after y-irradiation. The maximal increase in p53 concentration was similar in both induced and noninduced cells. These results thus indicate that PARP activity, in part, determines the duration, but not the magnitude, of the p53 response to DNA damage.

Burkitt Lymphoma↗