• S Bhattacharyya

      Articles written in Journal of Biosciences

    • Flowcytometric assessment of intracellular interferon -γ production in human CD4 + ve T-cells on mycobacterial antigen stimulation

      S Bhattacharyya S N Das A B Dey K Nagarkar J Lobo S K Kapoor H K Prasad

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      Interferon-(IFN-γ) has been considered to be a critical protective immunomodulatory component againstMycobacterium tuberculosis (M. tb.) infection. In this study T-cell proliferation and IFN-γ production upon stimulation with M. tb. were assessed in patients of pulmonary tuberculosis and healthy contacts. The studies were based on lymphocyte transformation test and detection of intracellular IFN-γ production by CD4 + ve T-cells by flowcytometry. Patients showed lower levels of proliferation, the stimulation index being in the range of 2.17 1.1 (mean + SD) compared to the contacts (SI = 4 59±1.6) (P < 0.01). The kinetics of intracellular induction of IFN-γ on M. tb. stimulation showed a proportional increase in the CD4 + ve T-cell population. The increase was maximal between 96–120 h of culture. In healthy contacts the number of IFN-γ expressing CD + ve T-cells increased to 2.5 to 41 × 104 cells/ml in M. tb. stimulated cultures compared to control cultures (0.1 – 15 × 104). In contrast patients showed no/marginal increase in CD4 + ve T-cell population expressing intracellular IFN-γ Thus the lack of induction of IFN in CD4 + ve T-cells in patients could be a critical shortcoming in their ability to combat tubercle bacilli infection.

    • Cloning of ribosomal RNA genes from an Indian isolate ofGiardia lamblia and the use of intergenic nontranscribing spacer regions in the differentiation ofGiardia from other enteric pathogens

      A K Sil P Das S Bhattacharyya S Ghosh D J Chattopadyay

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      The ribosomal RNA genes from an Indian isolate ofGiardia lamblia have been cloned and characterized with respect to size, composition and copy number. Southern blotting and rDNA cloning ofGiardia lamblia revealed that genes coding for ribosomal RNA (rRNA) are exceptionally small and are encoded within a 5.6 kb genome fragment repeat. The rDNA repeat unit of this isolate was found to be highly G-C rich like other human isolates and the physical map showed severalSmaI sites. There are 132 copies of the rDNA repeat unit per cell in a head to tail arrangement. Two fragments corresponding to intergenic (0.2 kb and 0.3 kb) region and one (0.8 kb) containing both an intergenic region and a small part of the small subunit ribosomal RNA (SS rRNA) have been identified within the rDNA. These were used in heterogeneity studies ofGiardia isolated from two geographic locations as well as in the analysis of cross reactivity with other enteric organisms. In Southern blots, all the three fragments were found to be highly specific for the differential diagnosis ofGiardia spp. from the other enteric pathogens. These findings should help in developing a sensitive and more specific method for the diagnosis of giardiasis over currently available techniques.

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