Biomedical subjects

T Ernst

Publications and source records attributed to T Ernst.

94 records · Page 6Linked to original sources

PubMedDate not supplied

Clinical tools for the 90s: magnetic resonance spectroscopy and metabolite imaging.

Magnetic resonance spectroscopy (MRS) is a flexible tool with real clinical utility. Examples from our experience in over 250 cases of clinical proton MRS are presented. Shorter echo time and reproducible water suppression increases the number of metabolites which can be detected and identified. Case reports illustrate the significance of altered ratios of N-acetylaspartate, choline, total creatine, myo-inositol, glutamate, glutamine, lactate, glucose, ketones, and, as an incidental finding, ethanol. Significant new information has resulted by applying proton MRS in chronic hepatic encephalopathy, diabetes mellitus and severe hypoxic encephalopathy ('near-drowning'). Potentially useful measurements have been made in normal brain maturation, ethanol related diseases, dementia (normal-pressure hydrocephalus), urea cycle defect and neuronal disease presenting as seizures. Metabolite imaging, particularly with proton, is clinically valuable, documenting the heterogeneity of biochemical disorders in seemingly focal lesions. A new method of specific 31-phosphorus--phosphocreatine imaging provides information in partially denervated skeletal muscle and is expected to have applications in brain.

Adult↗

PubMedDate not supplied

Brain N-acetyl aspartate concentrations measured by H MRS are reduced in adult male rats subjected to perinatal stress: preliminary observations and hypothetical implications for neurodevelopmental disorders.

The present study was undertaken to determine if the concentration of brain N-acetyl-aspartate (NAA), a putative neuronal marker, is reduced in adult rats subjected to stress during the perinatal period. As the prenatal stressor, pregnant rats were subjected to restraint stress for one hour twice daily from days 14-21 of gestation; stressed offspring were reared by normal dams and studied as adults. As the postnatal stressor, normal pups were reared by prenatally 'stressed' dams and studied as adults. As compared to non-stressed controls (n=6), NAA concentrations were significantly reduced 21 and 25% in left frontal cortex from the prenatal (n=4) and postnatal (n=6) stress groups. respectively. The data suggest that in perinatally stressed adult offspring permanent neuronal damage or loss has occurred. While no direct causal associations between perinatal stress and the developmental of particular disorders can be inferred from these limited data, the effects of perinatal stress on subsequent brain neuropathology are reviewed. particularly in relation to NAA. For hypothesis-generating purposes, the possible relevance of stress and NAA to the neurodevelopmental hypothesis of schizophrenia is discussed in greater detail.

Age Factors↗

PubMedDate not supplied

Analysis of flame retarded polymers and recycling materials.

Recycling activities on polymeric materials are increasing and becoming more and more important in recent years. For polymers containing no flame retardants, suitable recycling strategies already exist. In order to investigate the recyclability of flame retarded polymers that contain brominated flame retardants, a number of samples were analysed as received from a recycling company. Following the identification and sorting of the samples according to type of polymers and flame retardants, material recycling was tested for the flame retarded polymers identified to occur most frequently. The reactivity of the flame retardants during the recycling procedure was studied by analysing for brominated dioxins and furans. The results demonstrate that flame retarded polymers can be recycled under certain experimental conditions.

Bromine↗

PubMedDate not supplied

Direct 31P imaging in human limb and brain.

OBJECTIVE: This article describes two methods for direct imaging of the 31P-metabolites phosphocreatine (PCr) and inorganic phosphate (Pi) and their application in human brain and muscle. MATERIALS AND METHODS: All studies were performed on a 1.5 T whole-body GE Signa scanner, using bird cage resonators double-tuned to 31P and 1H. The pulse sequence was based on a multiple slice, multiple echo imaging sequence. Selection of the PCr signal was achieved either by selective excitation or by the extensive chemical shift artifact in read direction. Examinations were done in two diabetic patients, in four patients with cerebral neoplasms, and in several healthy subjects. RESULTS: In calf muscle, images showed uniform distribution of PCr in normal muscle; deficits corresponded to bony structures and neurovascular bundles. Repeated exercise (dorsiflexion of the foot) led to selective loss of PCr in the anterior muscle compartment. A simultaneous increase in Pi appeared as a spatially distinct map. Diabetic patients showed more severe changes of PCr distribution in the calf muscle at rest and during much milder exercise. Direct imaging in the human brain with chemical shift selective excitation was completed in 5-30 min. In normal cerebral cortex, PCr was uniformly distributed around deficits marking the lateral ventricles. Tumors exhibiting moderate to severe depletion of PCr appeared as well defined deficits in the PCr image. CONCLUSION: Direct imaging of PCr and Pi, with or without selective excitation of PCr, was effective in the human brain and limb. The methods described should lead to greatly improved fast phosphorus imaging. Clinical utility in peripheral ischemia and in localized energy deficits in the brain of patients with tumor, stroke, and other pathologies is anticipated.

Aged↗