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Biomedical subjects

A Narasimhan

Publications and source records attributed to A Narasimhan.

4 recordsLinked to original sources
PubMed2025

HLA-E and NKG2A Mediate Resistance to BCG Immunotherapy in Non-Muscle-Invasive Bladder Cancer.

Bacillus Calmette-Guérin (BCG) is the first-line therapy for high-grade non-muscle-invasive bladder cancer (NMIBC), yet many patients experience recurrence due to immune evasion. We identify HLA-E and NKG2A as mediators of adaptive resistance involving chronic activation of NK and T cells in BCG-unresponsive tumors. Prolonged IFN-γ exposure enhances HLA-E and PD-L1 expression on recurrent tumors, accompanied by the accumulation of NKG2A+ NK and CD8 T cells. HLA-Ehigh tumor cells preferentially cluster near CXCL12-rich stromal regions with dense effector cell presence, underscoring a spatially segregated tumor architecture. Although cytotoxic lymphocytes retain effector potential, their activity is restrained by HLA-E/NKG2A and PD-L1/PD-1 pathways located in their immediate neighborhood within the bladder tumor microenvironment. These data reveal a spatially organized immune escape program that limits anti-tumor immunity. Our findings support dually targeting NKG2A and PD-L1 checkpoint blockade as a rational, bladder-sparing strategy for patients with BCG-unresponsive NMIBC.

BCG-unresponsive↗
PubMed2004

Magnetic resonance evaluation of the interrelationship between articular cartilage and trabecular bone of the osteoarthritic knee.

OBJECTIVE: To use high-resolution magnetic resonance imaging (MRI) to determine the relationship between articular cartilage degeneration and trabecular bone changes of the femur, condyles and tibia in human knees with osteoarthritis (OA). METHODS: Subjects were divided into three groups: without OA (OA0), mild OA (OA1) and severe OA (OA2). Sagittal images of the knee (0.234 x 0.234mm2, 2-mm slice thickness) were obtained at 1.5T and used for calculating the volume and thickness of the femoral and tibial cartilage. Axial images (0.195 x 0.195mm2, 1-mm slice thickness) were used for calculating the trabecular bone structure parameters: apparent bone volume fraction, trabecular number, trabecular separation and trabecular thickness. RESULTS: Cartilage volume and thickness were less in patients with OA compared to normal controls (P<0.1). Articular cartilage thinning is associated with bone structure loss in the opposite femoral condyle (P<0.05). In varus OA, there were extensive correlations between medial tibia and medial femoral cartilage degeneration, and loss of bone structure in the lateral tibia and lateral condyle. Additional correlations existed between the compartmental differences (lateral minus medial) of cartilage thickness and bone structure. CONCLUSION: Degradation of articular cartilage within a compartment correlates with a loss of bone structure in the opposite compartment. The correlation between the (L-M) differences corroborates this relationship. Malalignment of the knee due to cartilage degeneration is associated with bone formation in the diseased condyle and bone resorption in the opposite compartment.

Age Factors↗
PubMed1993

Case report 786: Ewing's sarcoma of the left zygoma.

We present a relatively common tumor, Ewing's sarcoma, in an exceptionally rare site, the zygomatic bone, wherein the only symptom was swelling in the cheek despite intracranial extension. Ewing's sarcoma is not an uncommon tumor in the Asian Indian as it is in the African American. It appear to occur as frequently in the subcontinent as it does in Europe and in Americans of European descent.

Adolescent↗