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Articles by R. Ahmed
Total Records ( 4 ) for R. Ahmed
  B Youngblood , C. W Davis and R. Ahmed
 

Clonal expansion of virus-specific naive T cells during an acute viral infection results in the formation of memory CD8 T cells that provide the host with long-term protective immunity against the pathogen. Memory CD8 T cells display enhanced effector functions compared with their naive precursors, allowing them to respond more rapidly and effectively to antigen re-encounter. The enhanced functions of memory CD8 T cells are mediated by heritable changes in gene regulation. Expression of select transcription factors along with locus-specific epigenetic modifications are coupled to and are essential in the formation of memory-specific gene expression patterns. Here, we will review the changes in gene expression that accompany development of memory CD8 T cells and discuss chromatin modifications as a potential means for heritable propagation of these changes during homeostatic cell division of self-renewing memory CD8 T cells. Also, we will discuss therapies that manipulate heritable gene regulation as a potential mechanism to restore function to non-functional memory CD8 T cells to combat chronic viral infection.

  R. Ahmed , C.M. Sinnathambi and D. Subbarao
  Kinetics of decoking of spent reforming catalyst has been studied using a Thermo Gravimetric Analyzer (TGA) in presence of N2 and air. It is found that the major portion of the coke species was hard coke which has activation energy equal to 86.3 kJ mol-1. Slow heating rate and appropriate temperature are monitored to optimize the de-Coking process. Fourier Transform Infrared spectroscopy (FTIR) analysis has been applied to study the structure of coke deposited on supported metal catalyst (soft coke).
  M. Rafique Khan , R. Ahmed , M. Rahim Khan , A. Hayat and M. Khalid
  The adult butterflies were collected from ten localities of Distt. Bagh through out the year 1998. A total of 27 species belonging to 5 families and 15 genera were collected. Diversity was calculated by using Shannon-Wiener`s diversity index, Shannon`s equitability, Margalef`s index, Simpson`s index and RI index. The calculated values showed that diversity was slightly higher at Sudhan Gali and Mang Bajri, where as it was lower at Naumanpura. None of the reported species was found to be threatened to become extinct or found to be favored by enriched flora.
  D Masopust , D Choo , V Vezys , E. J Wherry , J Duraiswamy , R Akondy , J Wang , K. A Casey , D. L Barber , K. S Kawamura , K. A Fraser , R. J Webby , V Brinkmann , E. C Butcher , K. A Newell and R. Ahmed
 

Migration to intestinal mucosa putatively depends on local activation because gastrointestinal lymphoid tissue induces expression of intestinal homing molecules, whereas skin-draining lymph nodes do not. This paradigm is difficult to reconcile with reports of intestinal T cell responses after alternative routes of immunization. We reconcile this discrepancy by demonstrating that activation within spleen results in intermediate induction of homing potential to the intestinal mucosa. We further demonstrate that memory T cells within small intestine epithelium do not routinely recirculate with memory T cells in other tissues, and we provide evidence that homing is similarly dynamic in humans after subcutaneous live yellow fever vaccine immunization. These data explain why systemic immunization routes induce local cell-mediated immunity within the intestine and indicate that this tissue must be seeded with memory T cell precursors shortly after activation.

 
 
 
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