Biomedical subjects

V Gulani

Publications and source records attributed to V Gulani.

4 recordsLinked to original sources

PubMed2001

Apparent diffusion tensor measurements in myelin-deficient rat spinal cords.

The apparent diffusion tensor (ADT) was measured in excised and fixed spinal cords from myelin-deficient (md) rats and age-matched controls. These data were used to obtain the principal diffusivities of the ADT, and also the scalar invariant parameters _D (averaged principal diffusivity) and A(sigma) (anisotropy index) for four white matter and two gray matter regions. The results for white matter regions showed that the principal diffusivities were significantly higher for md animals, and while the _D was increased in tissue from md animals, the A(sigma) was found to be decreased. Grey matter _D was measured to be between those of white matter from control and md animals, and the A(sigma) was much smaller than that of white matter from both sets of animals, indicating that diffusion in md white matter is more anisotropic than in gray matter. The results show that while myelination is not a prerequisite for diffusion anisotropy, it does influence the magnitude of the observed anisotropy. Magn Reson Med 45:191-195, 2001.

Animals↗

PubMed2001

Magnetic resonance microscopy of morphological alterations in mouse trabecular bone structure under conditions of simulated microgravity.

This work describes the use of magnetic resonance (MR) microscopy to examine changes in tibial trabecular bone structure in mice following 28 days of hindlimb suspension, a model simulating the effects of microgravity in rodents. In this first MR study involving mice, analysis of 3D images showed that apparent bone volume fraction, trabecular number, and trabecular thickness were decreased, and apparent trabecular spacing increased, significantly (P < 0.05) in hindlimb-suspended mice compared to controls. These changes agreed well with light microscopy measurements from an independent study and also with actual spaceflight experiments with rats.

Animals↗

PubMed1999

Apparent water diffusion measurements in electrically stimulated neural tissue.

The effect of stimulation on diffusion characteristics of electrically stimulated neural tissue was examined. Bullfrog nerves and spinal cords were excised and stimulated electrically during magnetic resonance imaging, and the apparent diffusion coefficients (ADCs) of water parallel and perpendicular to the long axes of the specimens were mapped with and without stimulation of the tissue. Electrophysiological recordings were used to determine the viability of the tissue after each experiment. No stimulus-related ADC changes were observed in either the peripheral nervous system or the central nervous system tissue. These experiments may help to define further the nature of previously reported ADC changes in stimulated neural tissue in situ.

Animals↗

PubMed1997

A multiple echo pulse sequence for diffusion tensor imaging and its application in excised rat spinal cords.

A new imaging sequence for rapid determination of the apparent self-diffusion tensor of water was developed and tested on fixed excised rat spinal cords. To reduce the time required to determine the tensor, the sequence utilized a new single-shot approach with multiple spin echoes. An assumption of cylindrical symmetry in the sample was made, thus requiring the measurement of only four of the six unique elements of the tensor. This assumption was found experimentally to be valid, and the results obtained using the new sequence were found to be quantitatively the same as results obtained using a standard spin-echo sequence.

Animals↗