Preparation and light-directed activation of caged proteins.
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Light↗
Biomedical subjects
Partha Roy
Publications and source records attributed to Partha Roy.
Microscope-based techniques to study cell adhesion and migration.
Modern light microscopy has evolved to provide a variety of quantitative imaging techniques and also the capability to perturb structure-function relationships in living cells. The advances have been especially useful in the study of cell adhesion and migration. This review will focus on how such microscopy-based techniques can be useful in situ to study the molecular interactions and dynamics, to locally perturb actin-based structures and to measure the traction forces exerted by motile cells.
Actins↗
Dissecting the link between stress fibres and focal adhesions by CALI with EGFP fusion proteins.
Chromophore-assisted laser inactivation (CALI) is a light-mediated technique used to selectively inactivate proteins within cells. Here, we demonstrate that GFP can be used as a CALI reagent to locally inactivate proteins in living cells. We show that focused laser irradiation of EGFP-alpha-actinin expressed in Swiss 3T3 fibroblasts results in the detachment of stress fibres from focal adhesions (FAs), whereas the integrity of FAs, as determined by interference reflection microscopy (IRM), is preserved. Moreover, consistent with a function for focal adhesion kinase (FAK) in FA signalling and not FA structure, laser irradiation of EGFP-FAK did not cause either visible FA damage or stress fibre detachment, although in vitro CALI of isolated EGFP-FAK decreased its kinase activity, but not its binding to paxillin. These data indicate that CALI of specific FA components may be used to precisely dissect the functional significance of individual proteins required for the maintenance of this cytoskeletal structure. In vitro CALI experiments also demonstrated a reduction of EGFP-alpha-actinin binding to the cytoplasmic domain of the beta(1) integrin subunit, but not to actin. Thus, alpha-actinin is essential for the binding of microfilaments to integrins in the FA. CALI-induced changes in alpha-actinin result in the breakage of that link and the subsequent retraction of the stress fibre.
3T3 Cells↗
Bioavailability study of a 1200 mg miconazole nitrate vaginal ovule in healthy female adults.
This study was undertaken to determine the bioavailabilityof a 1200 mg miconazole nitrate vaginal ovule in 20 healthy premenopausal females following a single application (Day 1, Group 1) and two applications, 48 hours apart (Day 1 and Day 3, Group 2). In Dose Group 1 (n = 10), the mean Cmax of 10.7 ng/ml occurred at 18.4 hours. The average plasma miconazole concentration was calculated to be 5.7 ng/ml during the 4- to 96-hour time interval. In Dose Group 2 (n = 10), mean Cmax values were 10.8 ng/ml and 12.0 ng/ml and occurred at 18.4 hours (Day 1) and 16.0 hours (Day 3), respectively. Comparing AUC0-48 on Days 1 and 3 (338 vs. 408 ng x h/ml) indicated small accumulation of plasma miconazole, while AUC0-48 obtained from Dose Group 2, Day 1 was similar to that of Dose Group 1 (338 vs. 329 ng x h/ml, respectively). Plasma miconazole profiles were best described by a monoexponential equation with zero-order input. Pharmacokinetic simulations performed on the pooled data from two dose groups (n = 20) suggest a steady-state accumulation after five doses administered daily or three doses taken once every other day. Drug exposure was similar to that of the marketed formulation (MONISTAT 7 vaginal cream), applied once daily for 7 days and more than 100-fold less than that reported when given intravenously or orally.
Administration, Intravaginal↗