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Biomedical subjects

D Banerjee

Publications and source records attributed to D Banerjee.

At least 37 records · Page 2Linked to original sources
PubMed1992

Sequence analysis of polymerase chain reaction amplified t(14;18) chromosomal breakpoints in formalin fixed, paraffin wax embedded follicular lymphoma.

AIMS: To determine whether junctional sequences of rearranged chromosomes can be amplified by use of the polymerase chain reaction (PCR) and whether direct sequence analysis of the PCR products is possible, using DNA from formalin fixed, paraffin wax embedded biopsy specimens. METHODS: DNA was extracted from paraffin wax embedded, formalin fixed lymphoma specimens, and junctional sequences of rearranged chromosomes were amplified by the PCR. The products were used as templates for asymmetrical PCR. Subsequently, direct sequence analysis was performed using the chain termination method. RESULTS: Formalin fixed, paraffin wax embedded biopsy specimens and PCR amplification could be used to determine the nucleotide sequences of junctional regions of rearranged chromosomes t(14;18) from patients with follicular lymphoma. CONCLUSION: The identification of junctional sequences of the translocation in follicular lymphoma provides a molecular "fingerprint" of t(14;18) of the lymphoma of an individual patient and can be used for the detection of clone specific DNA in any biopsy tissue obtained from the patient. The strategy used for rapid sequence analysis of PCR amplified DNA sequences will be useful in many areas of molecular pathology.

Base Sequence↗
PubMed1992

Head and neck squamous cell carcinoma cell line-induced suppression of in vitro lymphocyte proliferative responses.

Tumour-infiltrating lymphocytes (TILs) are often difficult to expand in vitro. In some cases this has been attributable to immunosuppression mediated by the elaboration of prostaglandins by either tumor cells or tumor-infiltrating monocytes. In this laboratory, freshly prepared TILs containing single-cell suspensions of head and neck tumors displayed both poor proliferation as well as minimal responsiveness to indomethacin-mediated reversal of immunosuppression. In order to investigate tumor-mediated immunosuppression further, a system was developed whereby a new cell line of head and neck squamous cell carcinoma was used to suppress allogeneic peripheral blood mononuclear cell proliferation in response to phytohemagglutinin (PHA) and Interleukin-2 (IL-2). Tumor cells were able to suppress peripheral blood mononuclear cell (PBMNC) proliferation up to 95%. This suppressive effect was dependent on tumor cell number and was reversible by the use of higher concentrations of PHA, but not by increased concentrations of IL-2. Suppression was immediate when IL-2 was used as the stimulus for proliferation, but required extended lymphocyte/tumor cell contact when PHA was used. Flow cytometric analysis of tumor-exposed and PHA-stimulated PBMNCs revealed a decrease in both the number of cells expressing IL-2 receptors as well as the density of IL-2 receptors per cell. This pattern of suppression, as well as the reversibility of suppression by indomethacin, implicates prostaglandins in the mechanisms by which these tumor cells mediate immunosuppression.

Carcinoma, Squamous Cell↗
PubMed1992

Enzymes of the thymidylate cycle as targets for chemotherapeutic agents: mechanisms of resistance.

This brief review should serve to indicate that it is possible to assess tumor sensitivity to antifolates using fresh human tissue in short-term culture. The assays described differ from general assays of tumor sensitivity, such as the clonogenic assay or assays that measure 3H-thymidine incorporation as an indicator of cell viability (32-34), in that the effect of a drug on a human specific target (dihydrofolate reductase) is measured. These specific assays also may prove to be extremely useful in the detection of acquired drug resistance and for new analog drug development. In a general sense, this type of assay may eventually also be useful for guiding and selecting treatment for individual patients with other drugs with known mechanisms of action. Knowledge of the basis of tumor resistance is essential to develop new approaches to treatment, such as the use of other folate analogs that may still be effective, and to devise ways in which to selectively inhibit tumor cell growth using new analogs (trimetrexate) and leucovorin.

Antimetabolites, Antineoplastic↗
PubMed1992

The potential clinical impact of the fine needle aspiration/flow cytometric diagnosis of malignant lymphoma.

The objective of this study was to determine the potential application of fine needle aspiration (FNA) and flow cytometry (FCM) for the diagnosis of non-Hodgkin's lymphoma (NHL). At our institution, we have used FNA coupled with FCM to accurately diagnose both reactive lymphoid processes and most lymphomas in a prospective series of more than 90 patients. A retrospective review of 266 patients with NHL who were treated at the London (Ont.) Regional Cancer Centre over a five-year period was performed. Two-thirds presented with palpable lymphadenopathy which would have been amenable to FNA. Based upon the results of our prospective study, FNA/FCM could have provided an accurate diagnosis of malignancy for these patients. Furthermore, the subclassification of the lymphomas would have been accurate in 75% of cases. For 25% of patients, including those with T-cell lymphoma, accurate subclassification may have been problematic. Fifty of the 266 patients developed recurrences during the period of study. Ninety per cent of these were at sites amenable to FNA. Furthermore, the cytomorphology could have indicated whether transformation to a higher grade of lymphoma had occurred. Currently, FNA coupled with FCM is an under-utilized diagnostic technique which has great potential for the investigation of patients with both newly diagnosed and recurrent lymphoma.

Adolescent↗
PubMed1991

Isolation, characterization and sequencing of the chicken apolipoprotein-AI-encoding gene.

The chicken ApoAI gene has been isolated and characterized. This gene contains three introns: the first is situated after nucleotide (nt) 41 in the 5'-untranslated region of the gene, the second interrupts the codon specifying the Gly-10 of the prepeptide, and the third disrupts the codon for Asp42 in the mature ApoAI protein. The chicken ApoAI gene has 62.6% sequence similarity with the human and 65.0% similarity with the rat gene. Intron-exon organization of the chicken gene is similar to that of human and rat ApoAI genes. Two different transcriptional start points (tsp), only 2 nt apart from each other, have been obtained for the chicken ApoAI gene. The 5'-flanking sequence of the gene contains TAAATA (TATA-like box) and CCACAT (CCAAT-like box) sequences, which are located 21 bp and 96 bp upstream from the tsp, respectively. This gene's sequence and structural organization provide a basis for future studies of the regulation of chicken ApoAI gene expression.

Amino Acid Sequence↗
PubMed1991

Immunohistochemical localization of metallothionein in transitional cell carcinoma of the bladder.

Metallothionein is a metal binding protein thiol found in high concentrations in the liver and kidney. Recent evidence has linked overexpression of cellular metallothionein with tumor cell resistance to chemotherapeutic drugs, such as alkylating agents and cis-diamminedichloroplatinum (II) (cisplatin). We studied the metallothionein content of 9 human transitional cell carcinomas of the bladder with immunohistochemical methods. All tumors stained positive for metallothionein and the staining was localized almost exclusively to the cytoplasm. Uroepithelium displaying dysplastic changes or carcinoma in situ demonstrated the greatest intensity of staining, while staining in the invasive portions of the tumor was weak and variable. These findings were of interest, since combination chemotherapy of invasive transitional cell carcinoma of the bladder often is ineffective against carcinoma in situ. Normal uroepithelium stained strongly in all 3 patients who experienced disease progression and death, and in only 1 of the 5 who are currently without evidence of disease.

Aged↗
PubMed1991

Blood transfusions and phenotypic immune profile in head and neck cancer patients undergoing surgical resection.

Recent papers in the general surgery and otolaryngology literature have shown a positive correlation between blood transfusion and decreased survival in cancer patients. This is felt to be due to immunosuppression (not yet defined) induced by the transfusion. We prospectively analyzed the peripheral blood immune profiles of patients undergoing surgery for control of their squamous cell carcinoma of the upper aerodigestive tract. Pre- and postoperative profiles were examined. T4, T8, natural killer cells, and interleukin 2 receptor-positive T cell subsets were analyzed by flow cytometry. Statistical analysis indicated a significant difference between the non-transfused and transfused subgroups, with the transfused group having a decrease in their T helper cell and interleukin 2 receptor positive helper cell populations. This supports other literature which shows an increased recurrence rate in the transfused patient population. The patients were analyzed comparing blood transfusions, immune status, initial stage of disease, the nodal status of the disease, tumor differentiation, and patient's age yielding transfusion as the greatest single contributing factor to the observed immunological changes.

Adult↗
PubMed1990

Identification and characterization of a mutation in the dihydrofolate reductase gene from the methotrexate-resistant Chinese hamster ovary cell line Pro-3 MtxRIII.

A methotrexate-resistant Chinese hamster ovary cell line (Pro-3 MtxRIII), resistant due to a low-level amplified, altered target enzyme, dihydrofolate reductase (DHFR), has been characterized on the molecular level. The cDNA and coding regions of all six DHFR exons were amplified in vitro using Taq polymerase and directly sequenced. Analysis of the Pro-3 MtxRIII DHFR cDNA demonstrated a C----T base transition at nucleotide 67 that results in the substitution of phenylalanine for leucine at residue 22 and the loss of a BsaI site in the Pro-3 MtxRIII cDNA. This mutation results in a decreased binding of methotrexate to the altered enzyme. Molecular modeling of Leu22----Phe supports the concept of the importance of Leu22 in the active site of the enzyme and indicates that replacement with phenylalanine will decrease the binding of methotrexate.

Amino Acid Sequence↗
PubMed1990

Intracellular fate of fibrinogen B beta chain expressed in COS cells.

Full-length fibrinogen B beta cDNA was subcloned into an expression vector, pBC12BI, and transfected into COS cells. B beta chain expression was measured by pulse-labelling cells with L-[35S]methionine, immunoprecipitating the B beta chain with antibody to fibrinogen and separating the nascent radioactive protein by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). B beta chain was expressed in transfected COS cells but was not secreted into the medium. Treatment with endoglycosidase H showed that non-secreted B beta chain contains mannose-rich carbohydrates rather than the complex form of carbohydrate which occurs in plasma fibrinogen and indicates that B beta chain is not transported to the Golgi apparatus. In transfected COS cells, antibody to fibrinogen co-immunoprecipitated B beta chain and 78 kDa immunoglobulin-binding protein (BiP) and antibody to BiP immunoprecipitated BiP and nascent B beta chains. Non-secreted B beta chain was degraded intracellularly with a half-life of 5 h by enzymes which were not affected by incubating transfected cells with NH4Cl, which indicates a non-lysosomal pathway of degradation. These studies indicate that B beta chain by itself does not contain the signal for fibrinogen secretion and that non-secreted B beta chain is associated with BiP and degraded in the rough endoplasmic reticulum.

Animals↗
PubMed1990

Native fibrin gel networks and factors influencing their formation in health and disease.

Hydrated fibrin gels were studied by confocal laser 3D microscopy, liquid permeation and turbidity. The gels from normal fibrinogen were found to be composed of straight rod-like fiber elements which sometimes originated from denser nodes. In gels formed at increasing thrombin or fibrinogen concentrations, the gel networks became tighter and the porosity decreased. The fiber strands also became shorter. Gel porosity of the network decreased dramatically in gels formed at increasing ionic strengths. Shortening of the fibers were observed and fiber swelling occurred at ionic strength above 0.24. Albumin and dextran, when present in the gel forming system, affected the formation of more porous structures with strands of larger mass-length ratio and fiber thickness. This type of gels were also formed in plasma. Albumin and lipoproteins may be among the determinants for the formation of this type of gel structure in plasma. Gels formed when factor XIIIa instead of thrombin was used as catalyst for gelation showed a completely different structure in which lumps of polymeric material were held together by a network of fine fiber strands. Our studies have also shown that the methodologies employed may be useful in studies of gel structures in certain dysfibrinogenemias as well as in other diseases. We give examples of two patients with abnormal fibrinogen and of patients with ischaemic heart disease.

Adult↗
PubMed1990

Primary gastric T-cell lymphoma of suppressor-cytotoxic (CD8+) phenotype: discordant expression of T-cell receptor subunit beta F1, CD7, and CD3 antigens.

Primary gastric T-cell lymphomas are rare neoplasms, and all but one of the previously phenotyped cases have shown a helper-inducer phenotype. The present case is the second reported case of a primary gastric T-cell lymphoma of suppressor-cytotoxic phenotype. The tumor histology was similar to that described in some forms of node-based peripheral T-cell lymphomas. Phenotypic analysis revealed low expression of pan-T marker CD7, reduced expression of CD3, but higher density and frequency of expression of CD8 antigens that could be predicted on the basis of the pan-T markers. Natural killer cell (NK) related markers CD16, HNK-1 and NKH-1 were not expressed by the neoplastic cells. T-cell receptor (TCR) beta subunit expression was detected on fewer cells than would have been predicted on the basis of CD3 and CD8 expression, and TCR delta chain expression was undetectable.

Aged↗
PubMed1990

Immunogold labelling of tumour cells during NK/target cell interactions.

Using a system of immunocolloidal gold labelling, we have monitored the expression and distribution of transferrin receptors (TfRs) within the K562 cell line, during NK/target cell interactions. An indirect method of immunolabelling was used to effectively immunolabel tumour cells without disrupting the natural effector:target interactions. Successful localization of TfRs demonstrates the potential of the described technique for discerning antigenic distribution of other cell:cell interactions. Immunolabelling has also provided a useful method for demonstrating receptor down-regulation within NK target cells, as a proposed cause of reduced receptor expression by TPA-treated cells. Following 30 and 60 min incubation periods with TPA, approximately 15 and 30%, respectively, of the gold/antibody complexes were relocated from the surface membrane to an intracellular location within endocytotic vesicles. The demonstration of receptor down-regulation is important as a proposed cause of TPA-induced tumour cell resistance to NK-mediated cytolysis.

Cytotoxicity, Immunologic↗
PubMed1990

Whole cell preparation of squamous cell carcinoma for cytometric analysis of DNA.

To date, analysis of the DNA content of head and neck squamous cell carcinomas has relied on the homogenation of the entire tissue specimen and subsequent staining and quantitation of the naked nuclei. This methodology does not make allowance for the extremely variable nature of these tumors with respect to their cellular composition. Further, by destroying the cytoplasm and cell membranes, this methodology makes it impossible to distinguish the DNA content of the tumor cells from that of the background stromal and inflammatory cells. The authors present a methodology for the selective exclusion of inflammatory cell infiltrates from the DNA analysis of these tumors. Using this technique, it has been found that exclusion of the inflammatory cells allows the investigator to look more specifically at the malignant cell population. This has been most helpful in those samples in which the tumor cells have been diploid or near-diploid. With this technical refinement, the relationship between DNA ploidy and clinical prognosis may be more accurately assessed.

Aged↗
PubMed1990

Human monoclonal antibodies to neuroendocrine granules derived from tumor-infiltrating lymphocytes isolated from a primitive neuroectodermal tumor.

Tumor-infiltrating lymphocytes were isolated from a primitive neuroectodermal tumor and fused with GM4672 cells, resulting in hybrids secreting human IgM-kappa antibody, which is reactive to olfactory neuroblastoma tumor cells. Hybridoma clones 4F and 9G produce human monoclonal antibodies reactive to autologous and allogeneic neuroblastoma tumor cells and subsets of pancreatic islet cells in formalin-fixed tissues. They react specifically with dense core granules of glucagon and insulin-producing islet cells, but not with those in cells producing somatostatin. Calcitonin granules are not recognized by these antibodies. The area of localization of the granules is distinct from the component labeled by murine monoclonal antibodies to chromogranin A. The clones have remained stable in culture for over two years and continue to secrete up to 60 micrograms/mL of human IgM. This study demonstrates the possibility of directly analyzing the antibody repertoire of tumor-infiltrating B cells, and this technique may allow the development of human monoclonal antibodies to other novel cellular antigens.

Antibodies, Monoclonal↗