Biomedical subjects

Thiruvallur R Gowrishankar

Publications and source records attributed to Thiruvallur R Gowrishankar.

3 recordsLinked to original sources

PubMed2006

Microdosimetry for conventional and supra-electroporation in cells with organelles.

Conventional electroporation (EP) by 0.1 to 1 kV/cm pulses longer than 100 micros, and supra-electroporation by 10 to 300 kV/cm pulses shorter than 1 micros cause different cellular effects. Conventional EP delivers DNA, proteins, small drugs, and fluorescent indicators across the plasma membrane (PM) and causes moderate levels of phosphatidylserine (PS) translocation at the PM. We hypothesize that supra-EP is central to intracellular effects such as apoptosis induction and higher levels of PS translocation. Our cell system model has 20,000 interconnected local models for small areas of the PM and organelle membranes, small regions of aqueous media, appropriate resting potentials, and the asymptotic EP model. Conventional EP primarily affects the PM, but with a hint of endoplasmic reticulum involvement. Supra-EP can involve all of a cell's membrane at the largest fields. Conventional EP fields tend to go around cells, but supra-EP fields go through cells, extensively penetrating organelles.

Cell Physiological Phenomena↗

PubMed2006

Controlled nail trephination for subungual hematoma.

An injury to a finger or toe can result in a collection of blood under the nail plate that if unrelieved can cause extreme discomfort due to pressure. In this case, a 47-year-old man developed a subungual hematoma of the right thumb due to a crush injury. Controlled nail trephination was performed using a uniquely designed drill that penetrated the nail plate without breaching the nail bed. The subungual hematoma was successfully drained, and there was a substantial relief in pain over the subsequent 8 hours. This technique appears to be a quick and convenient method of evacuating subungual hematomas with minimal discomfort and minimal risk.

Drainage↗

PubMed2003

An approach to electrical modeling of single and multiple cells.

Previous theoretical approaches to understanding effects of electric fields on cells have used partial differential equations such as Laplace's equation and cell models with simple shapes. Here we describe a transport lattice method illustrated by a didactic multicellular system model with irregular shapes. Each elementary membrane region includes local models for passive membrane resistance and capacitance, nonlinear active sources of the resting potential, and a hysteretic model of electroporation. Field amplification through current or voltage concentration changes with frequency, exhibiting significant spatial heterogeneity until the microwave range is reached, where cellular structure becomes almost "electrically invisible." In the time domain, membrane electroporation exhibits significant heterogeneity but occurs mostly at invaginations and cell layers with tight junctions. Such results involve emergent behavior and emphasize the importance of using multicellular models for understanding tissue-level electric field effects in higher organisms.

Cells↗