Biomedical subjects
K Vijayraghavan
Publications and source records attributed to K Vijayraghavan.
Drosophila Heartless acts with Heartbroken/Dof in muscle founder differentiation.
The formation of a multi-nucleate myofibre is directed, in Drosophila, by a founder cell. In the embryo, founders are selected by Notch-mediated lateral inhibition, while during adult myogenesis this mechanism of selection does not appear to operate. We show, in the muscles of the adult abdomen, that the Fibroblast growth factor pathway mediates founder cell choice in a novel manner. We suggest that the developmental patterns of Heartbroken/Dof and Sprouty result in defining the domain and timing of activation of the Fibroblast growth factor receptor Heartless in specific myoblasts, thereby converting them into founder cells. Our results point to a way in which muscle differentiation could be initiated and define a critical developmental function for Heartbroken/Dof in myogenesis.
Discrimination in partnership: compartment-specific interactions of Hox proteins.
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Retrospective analysis of treatment of unresectable keloids with primary radiation over 25 years.
AIMS: The purpose of the study was to review retrospectively the role of primary radiotherapy for unresectable keloids. MATERIALS AND METHODS: Kilovoltage X-rays and mega-voltage electron beams were used to irradiate large bulky unresectable keloids. A total of 3750 cGy was given in five once-weekly fractions, over a period of 5 weeks. Eighty-six keloids in 64 patients were treated between 1977 and 2002. RESULTS: Ninety-seven per cent of this cohort had significant regression, and 3% had partial regression 18 months after completing radiotherapy. Both acute and long-term reactions were acceptable, and so far none of the patients have been reported as having cancer of any sort. Sixty-three per cent of the patients surveyed were very happy with the outcome of their treatment. CONCLUSION: Unresectable bulky symptomatic keloids can be satisfactorily treated with hypo-fractionated radiotherapy primarily using either kilovoltage X-rays or electron beams without significant short- or long-term side-effects.
The Drosophila homolog of the human transcription factor TEF-1, scalloped, is essential for normal taste behavior.
The scalloped (sd) locus of Drosophila melanogaster encodes a protein with a novel DNA binding domain bearing a high degree of similarity to the human transcription factor TEF-1 (Campbell et al., 1992). We demonstrate that sd mutants show defects in response to a number of taste stimuli. Higher stimulus concentrations are required to elicit behavioral responses from mutant larvae and adult flies. The electrophysiological responses of the peripheral taste neurons in the labellum were found to be normal, suggesting that an inability to detect stimuli is not the cause of the mutant phenotype. The range of mutant responses of sd alleles to salt and sugar stimuli define a functional requirement for the gene in the nervous system and provide an assay for the genetic and molecular analysis of this role.
Development of the indirect flight muscles of Drosophila.
We have followed the pupal development of the indirect flight muscles (IFMs) of Drosophila melanogaster. At the onset of metamorphosis larval muscles start to histolyze, with the exception of a specific set of thoracic muscles. Myoblasts surround these persisting larval muscles and begin the formation of one group of adult indirect flight muscles, the dorsal longitudinal muscles. We show that the other group of indirect flight muscles, the dorsoventral muscles, develops simultaneously but without the use of larval templates. By morphological criteria and by patterns of specific gene expression, our experiments define events in IFM development.