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Manoj K Sharma

Publications and source records attributed to Manoj K Sharma.

5 recordsLinked to original sources
PubMed2006

Arraying of intact liposomes into chemically functionalized microwells.

Here, we describe a protocol to bind individual, intact phospholipid bilayer liposomes, which are on the order of 1 microm in diameter, in microwells etched in a regular array on a silicon oxide substrate. The diameter of the wells is on the order of the liposome diameter, so only one liposome is located in each well. The background of the silicon oxide surface is functionalized with a PEG oligomer using the contact printing of a PEG silane to present a surface that resists the adsorption of proteins, lipid material, and liposomes. The interiors of the wells are functionalized with an aminosilane to facilitate the conjugation of biotin, which is then bound to Neutravidin. The avidin-coated well interiors bind the liposomes whose surfaces contain biotinylated lipids. The specific binding of the liposomes to the surface using the biotin-avidin linkage, together with the resistant nature of the background and the physical confinement of the wells, allows the liposomes to remain intact and to not unravel, rupture, and fuse onto the surface. We demonstrate this intact arraying using confocal laser scanning microscopy of fluorophores specifically tagging the microwells, the lipid bilayer, and the aqueous interior of the liposome.

Avidin↗
PubMed2005

Retinal location of the preferred retinal locus relative to the fovea in scanning laser ophthalmoscope images.

PURPOSE: It is difficult to determine the position of a preferred retinal locus (PRL) relative to the fovea in scanning laser ophthalmoscope (SLO) images as a result of disease-related retinal morphologic changes that obscure the fovea. To overcome this problem, we developed a method for determining retinal foveal position based on normal fixation position relative to the optic disk. The normal foveal position measurements can then be used to estimate the distance between a PRL and the fovea. METHODS: Using the SLO, foveal position was determined for 50 normal subjects by measuring the retinal locus of fixation relative to the optic disk in undistorted SLO images. The resulting normal foveal fixation area is described by a bivariate normal ellipse that can be plotted on any undistorted SLO image. Measurement reliability was assessed by repeated measurements. The PRL relative to the normal foveal fixation area was determined for 24 subjects with macular degeneration and bilateral central scotomas. RESULTS: The normal foveal fixation area based on all 50 subjects is described by a p = 0.9 bivariate ellipse whose centroid is located 12.6 degrees temporal to the temporal optic disk edge and 1.4 degrees inferior to a horizontal line bisecting the disk. PRL area is shown to increase with distance from the foveal fixation ellipse centroid. The shape of the PRL, characterized by the ratio of PRL ellipse major to minor axis, was found to depend on whether the PRL was vertically or horizontally aligned with the foveal fixation centroid. CONCLUSIONS: PRL position relative to the fovea can be reliably estimated by plotting the normal foveal fixation bivariate ellipse on undistorted SLO images of retinas in which the fovea is obscured as a result of the disease process.

Adult↗
PubMed2002

Rapid changes in postprandial blood glucose produce concentration differences at finger, forearm, and thigh sampling sites.

OBJECTIVE: To compare pre- and postmeal capillary blood glucose concentrations measured at the finger, forearm, and thigh in adults with diabetes. RESEARCH DESIGN AND METHODS: For phase 1, capillary blood glucose concentrations were measured at six time points (premeal and at approximately 60, 90, 120, 150, and 180 min postmeal) using a blood glucose monitoring system and technician-obtained samples collected from finger, forearm, and thigh sites of 42 adults with diabetes. The finger samples were also tested with a laboratory instrument. For phase 2, approximately 14 weeks later, the testing procedures were repeated with 38 subjects from the original study population. RESULTS: Meter finger results were accurate at all time points. Alternate sites tended to produce lower glucose readings compared to finger readings at times when glucose was increasing rapidly (60 and 90 min postmeal). Forearm-to-finger differences correlated with rates of glucose change (r = 0.56, P < 0.001), as did the thigh-to-finger differences (r = 0.52, P < 0.001). Other factors, such as subject age, BMI, diabetes type, and insulin dependence did not have a significant impact on site differences. When the testing procedures were repeated with the same subjects, the pattern of site differences was consistent, although individual results were variable. CONCLUSIONS: Changes in blood glucose immediately after a meal may be identified at finger sites before detection at forearm or thigh sites. Alternate site testing appears to be a useful option for routine self-monitoring before meals; however, patients and clinicians should recognize that results may be different from fingertip results when glucose levels are changing rapidly.

Adult↗
PubMedDate not supplied

Bacteriorhodopsin conjugates as anchors for supported membranes.

The sophistication of supported lipid bilayer membranes has increased steadily as new applications are being explored. In general, tethered lipids are used to anchor the lipid bilayer to the substrate. Here we describe a new type of anchoring system for supported lipid bilayers that is based on biotin-PEG3400-bacteriorhodopsin conjugates. Amine-based coupling was used to construct the polymer conjugates, followed by fluorophore labeling to enable confocal imaging. The bacteriorhodopsin-based anchoring system was used to construct solid-supported vesicles from streptavidin-coated microspheres. This method could provide a new route for the stability enhancement of supported lipid bilayer membrane assemblies.

Amino Acid Sequence↗