Publications by authors named "Jeff Dunn"

We investigate fiber placement issues associated with a hybrid magnetic resonance imaging (MRI) near-infrared (NIR) imaging technique for small animal brain studies. Location of the optical fibers on the cranium is examined, with an emphasis on maximizing the recovered resolution and contrast in the region of interest, which in this case is the murine brain. In a series of simulation studies, singular value decomposition of the Jacobian is used in order to determine the measurement sites that provide the most information about the region of interest.

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Purpose: To examine, using blood oxygen level dependent (BOLD) MRI and EPR oximetry, the changes in oxygenation of intracranial tumors induced by carbogen breathing.

Materials And Methods: The 9L and CNS-1 intracranial rat tumor models were imaged at 7T, before and during carbogen breathing, using a multi-echo gradient-echo (GE) sequence to map R(2)*. On a different group of 9L tumors, tissue pO(2) was measured using EPR oximetry with lithium phthalocyanine as the oxygen-sensitive material.

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Chemoreceptors in the ventral medulla contribute to the respiratory response to hypercapnia. Do they 'sense' intracellular pH (pHi)? We measured pHi in the ventral medulla or cortex (control) using 31P-NMR obtained via a novel 3 x 5 mm2 surface coil in anesthetized rats breathing air or 7% CO2. During air breathing over 240 min, pHi decreased slightly from 7.

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