Biomedical subjects

M A Foster

Publications and source records attributed to M A Foster.

94 records · Page 6Linked to original sources

PubMedDate not supplied

Multi-center trial with an in vitro NMR protocol. EEC Concerted Research Project.

The EEC Protocol for in vitro measurement of T1 and T2 presented in paper II of this series was tested in 15 centers on a variety of instruments. This article discusses the results of this protocol trial using biological samples (rat liver and thigh muscle) and two reference gel samples. Each reference gel was prepared as a single batch, dispensed into appropriate sample tubes and sent to all participants. Details of instrument types and operating conditions are given, along with measurement frequencies and temperatures and the results of precision testing. The relaxation time measurements from the gels for the trial are compared with temperature and frequency effects examined in independent centers under similar conditions. The relaxation time values for biological tissues are examined in the light of the scatter of such values in the general literature. To check the effects of data analysis methods on relaxation times, full relaxation data for one reference sample was provided by each group. This was re-analyzed in three centers using different methods; these results are compared with the values calculated by each group using its own method. In general, the results from different groups show good consistency with the reference values. The use of this Protocol has helped reduce scatter in results from biological samples and has provided information for improvement of individual operating conditions and improvement of the protocol to its final form.

Animals↗

PubMedDate not supplied

1H-NMR relaxation times and water content of red blood cells from chronic alcoholic patients during withdrawal.

Red blood cell proton nmr, T1 and T2 times, and water content were measured for normal control subjects and thirteen patients with chronic alcoholism during the withdrawal phase. T1 and T2 were significantly increased without significant alteration in cell water content. The relaxation times were more markedly affected in those with symptoms of delirium tremens. These findings suggest that the intracellular free:bound water states rather than water content is the more likely explanation for these changes. The results are discussed in relation to similar findings obtained from in vivo studies in man and in vitro studies in animals.

Adult↗

PubMedDate not supplied

Regional variation in rat brain proton relaxation times and water content.

Relaxation times (T1 and T2) and water content are measured in frontal cortex, amygdaloid cortex, hippocampus, mid-brain and cerebellum of rat brain. Differences are found in relaxation times, between areas containing a mixture of grey and white matter, and grey matter only. Differences were also found between certain grey matter areas. Relaxation times correlated with water content.

Amygdala↗

PubMedDate not supplied

Paramagnetic NMR contrast agents. Development and evaluation.

Paramagnetic ions could be theoretically used as NMR contrast agents because of their effect upon T1. However, the toxicity of these ions prevents their application. By the formation of appropriate chemical complexes with these ions, the toxicity of these agents can be substantially reduced while maintaining the paramagnetic effect. Two potential NMR contrast agents, one for oral use and one for intravenous administration, were developed and evaluated both in vitro and in vivo. The effect upon T1 in vitro of these paramagnetic compounds was determined using a JEOL FX-90Q NMR spectrometer. These agents were evaluated in vivo in dogs with a Technicare 0.3 tesla superconducting magnet system and in rabbits with the Aberdeen 0.04 tesla resistive NMR imager. Using calculated T1 NMR images, a nontoxic dose of gadolinium oxalate provided visualization of the gastrointestinal tract. Intravenous administration of chromium EDTA provided enhancement of the kidneys, ureters, and bladder, thereby potentially allowing for the evaluation of renal function with magnetic resonance imaging. Stable paramagnetic complexes can serve as effective, nontoxic, oral and intravenous NMR contrast agents.

Administration, Oral↗