Biomedical subjects

M Garwood

Publications and source records attributed to M Garwood.

57 records · Page 4Linked to original sources

PubMed1981

Oxygen fields in specific spinal loci of the canine spinal cord.

Oxygen tension (PO2) measurements were made in the dog spinal cord with a small recessed-tip oxygen microelectrode. The use of vibration and specific marking techniques has allowed the elimination of tissue compression artifacts and the mapping of regional PO2 in the thoracic spinal cord. A symmetrical distribution of PO2 values can be shown for the lateral white funiculi; the gray matter and dorsal columns have multimodal distributions. Statistical evaluation showed all these areas to have different PO2 profiles; PO2 values (mmHg) were 61.2 +/- 12.4 for the lateral white funiculi, 55.3 +/- 19.0 for the dorsal columns, and 30.0 +/- 13.6 in spinal gray. The relatively normal distribution patterns of these oxygen tensions indicate that traditional statistical methods may be used to compare and evaluate oxygen diffusion fields in the adult spinal cord.

Animals↗

PubMedDate not supplied

Applications of magnetic resonance in model systems: tumor biology and physiology.

A solid tumor presents a unique challenge as a system in which the dynamics of the relationship between vascularization, the physiological environment and metabolism are continually changing with growth and following treatment. Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) studies have demonstrated quantifiable linkages between the physiological environment, angiogenesis, vascularization and metabolism of tumors. The dynamics between these parameters continually change with tumor aggressiveness, tumor growth and during therapy and each of these can be monitored longitudinally, quantitatively and non-invasively with MRI and MRS. An important aspect of MRI and MRS studies is that techniques and findings are easily translated between systems. Hence, pre-clinical studies using cultured cells or experimental animals have a high connectivity to potential clinical utility. In the following review, leaders in the field of MR studies of basic tumor physiology using pre-clinical models have contributed individual sections according to their expertise and outlook. The following review is a cogent and timely overview of the current capabilities and state-of-the-art of MRI and MRS as applied to experimental cancers. A companion review deals with the application of MR methods to anticancer therapy.

Animals↗

PubMedDate not supplied

Measurement of human brain lithium in vivo by MR spectroscopy.

PURPOSE: To quantify lithium in the human brain. METHODS: A 7Li MR spectroscopy method was developed with special features for high precision including: a) sampling a large cerebral volume to maximize the signal-to-noise ratio; b) adiabatic excitation pulses to ensure uniform spin mutation; c) morphometric analysis of the MR images of the sampled cerebrum; d) a mathematical model derived from empirical data to correct for receiver inhomogeneity effects; and e) a long interpulse delay, to eliminate errors arising from uncertain T1 values. RESULTS: A theoretical precision of 5.2% and an accuracy of better than 7.2% in someone with a brain lithium level of 1.0 mEq per liter of cerebral volume and precision and accuracy of 6.8 and 8.6%, respectively, in someone with 0.5 mEq/L brain lithium was calculated. This level of precision was surpassed in phantoms and patients. Brain lithium in 10 patients treated with lithium carbonate varied from 0.52 to 0.87 mEq/L (mean = 0.58 mEq/L; SD = 0.17 mEq/L). Brain-to-serum lithium ratios varied from 0.50 to 0.97 mEq/L (mean = 0.77 mEq/L; SD = 0.14 mEq/L). Substantial variation in brain lithium was observed in patients with similar serum lithium. CONCLUSIONS: A highly reliable method to quantify human brain lithium by 7Li MR spectroscopy has been implemented. Unexpected variability in brain versus serum levels of lithium was detected in patients with bipolar disease.

Brain Chemistry↗