Molecular basis of VEGFR1 autoinhibition at the plasma membrane.

Ligand-independent activation of VEGFRs is a hallmark of diabetes and several cancers. Like EGFR, VEGFR2 is activated spontaneously at high receptor concentrations. VEGFR1, on the other hand, remains constitutively inactive in the unligated state, making it an exception among VEGFRs. Ligand stimulation transiently phosphorylates VEGFR1 and induces weak kinase activation in endothelial cells. Recent studies, however, suggest that VEGFR1 signaling is indispensable in regulating various physiological or pathological events. The reason why VEGFR1 is regulated differently from other VEGFRs remains unknown. Here, we elucidate a mechanism of juxtamembrane inhibition that shifts the equilibrium of VEGFR1 towards the inactive state, rendering it an inefficient kinase. The juxtamembrane inhibition of VEGFR1 suppresses its basal phosphorylation even at high receptor concentrations and transiently stabilizes tyrosine phosphorylation after ligand stimulation. We conclude that a subtle imbalance in phosphatase activation or removing juxtamembrane inhibition is sufficient to induce ligand-independent activation of VEGFR1 and sustain tyrosine phosphorylation.

Cytology Microarray on Cell Block Preparation: A Novel Diagnostic Approach in Fluid Cytology.

BACKGROUND: The cytological examination of serous body effusions to diagnose and stage malignancy is well accepted in clinical medicine. Conventional smear (CS) and cell block (CB) study has to be complemented with immunohistochemistry (IHC) for a definitive diagnosis of malignancy and also to differentiate it from reactive mesothelial cells. Cytology microarray (CMA) is a modification of tissue microarray which involves core needle biopsy of multiple cell blocks and embedding it in a single block. AIM: The aim of this study was to assess the effectiveness of IHC technique in CMA for rapid diagnosis of malignancy and to reduce the cost of testing. MATERIALS AND METHODS: In this study, 82 pleural fluids were collected and subjected to CS and CB study followed by IHC in CMA blocks. Six commonly used antibodies were applied to confirm malignancy and diagnose the primary. RESULTS: Nineteen cases were diagnosed as malignancy by CB method. MOC-31 confirmed adenocarcinoma deposit in 67% cases of which 44% were proved to be of lung primary by TTF1. CONCLUSIONS: IHC on CMA blocks of effusion fluids is a very effective technique that can significantly reduce the cost of testing by >70%.

Role of Cytology in Early Diagnosis of Cerebrotendinous Xanthomas.

Cerebrotendinous xanthomatosis is a rare autosomal recessive lipid storage disease characterized by widespread tissue deposition of two neutral sterols, cholestenol and cholesterol, resulting in tendinous xanthomas, juvenile cataracts, progressive neurological defects, and premature death from arteriosclerosis. Because it is a treatable cause of cerebellar ataxia and dementia, its early diagnosis is desirable. Here, we have reported the case of an 11-year-old boy with this disorder who was diagnosed based on the cytological findings of fine needle aspiration and clinical features.