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Biomedical subjects

T Ptak

Publications and source records attributed to T Ptak.

9 recordsLinked to original sources
PubMed1999

Chronic toxic encephalopathy in a painter exposed to mixed solvents.

This paper describes symptoms and findings in a 57-year-old painter who had been exposed to various organic solvents for over 30 years. He began to work as a painter at 16 years of age, frequently working in poorly ventilated areas; he used solvents to remove paint from the skin of his arms and hands at the end of each work shift. The patient and his family noticed impaired short-term memory function and changes in affect in his early forties, which progressed until after he stopped working and was thus no longer exposed to paints and solvents. After the patient's exposures had ended, serial neuropsychological testing revealed persistent cognitive deficits without evidence of further progression, and improvement in some domains. Magnetic resonance imaging revealed global and symmetrical volume loss, involving more white than gray matter. The findings in this patient are consistent with chronic toxic encephalopathy and are differentiated from other dementing processes such as Alzheimer's disease, multi-infarct (vascular) dementia, and alcoholic dementia. Previous descriptions in the literature of persistent neurobehavioral effects associated with chronic exposure to organic solvents corroborate the findings in this case.

Brain Diseases↗
PubMed1999

Investigation of apparent diffusion coefficient and diffusion tensor anisotrophy in acute and chronic multiple sclerosis lesions.

BACKGROUND AND PURPOSE: The various stages of multiple sclerosis (MS) are characterized by de- and remyelination as well as by inflammation. Diffusion MR imaging is sensitive to tissue water motion, which might correspond to these pathologic processes. Our purpose was to demonstrate differences in apparent diffusion coefficient (ADC) and diffusion tensor anisotropy in acute and chronic MS plaques and in normal-appearing brain. METHODS: Twelve MS patients underwent conventional and full-tensor diffusion MR imaging with B = 1221 s/mm2. Derivation of trace ADC and calculation of anisotropic scalars, including eccentricity, relative anisotropy (RA), and fractional anisotropy (FA) was performed on a per-pixel basis. Regions of interest of plaques and normal structures were determined on coregistered maps. MS lesions were classified as acute, subacute, or chronic on the basis of their appearance on conventional images and in relation to clinical findings. RESULTS: Seven patients had acute plaques with a concentric arrangement of alternating high and low signal intensity on diffusion-weighted images. In nine acute lesions, plaque centers had high ADC with reduced anisotropy compared with rim, normal-appearing white matter (NAWM), and chronic lesions. The thin rim of diffusion-weighted hyperintensity surrounding the center showed variable ADC and anisotropic values, which were not statistically different from NAWM. Subacute and chronic MS lesions had intermediate ADC elevations/anisotropic reductions. Calculated FA pixel maps were superior to eccentricity or RA maps; however, quality was limited by signal-to-noise constraints. CONCLUSION: ADC and diffusion anisotropic scalars reflect biophysical changes in the underlying pathology of the demyelinating process.

Adolescent↗
PubMed1997

Quantitative neuropathology by high resolution magic angle spinning proton magnetic resonance spectroscopy.

We describe a method that directly relates tissue neuropathological analysis to medical imaging. Presently, only indirect and often tenuous relationships are made between imaging (such as MRI or x-ray computed tomography) and neuropathology. We present a biochemistry-based, quantitative neuropathological method that can help to precisely quantify information provided by in vivo proton magnetic resonance spectroscopy (1HMRS), an emerging medical imaging technique. This method, high resolution magic angle spinning (HRMAS) 1HMRS, is rapid and requires only small amounts of unprocessed samples. Unlike chemical extraction or other forms of tissue processing, this method analyzes tissue directly, thus minimizing artifacts. We demonstrate the utility of this method by assessing neuronal damage using multiple tissue samples from differently affected brain regions in a case of Pick disease, a human neurodegenerative disorder. Among different regions, we found an excellent correlation between neuronal loss shown by traditional neurohistopathology and decrease of the neuronal marker N-acetylaspartate measured by HRMAS 1HMRS. This result demonstrates for the first time, to our knowledge, a direct, quantitative link between a decrease in N-acetylaspartate and neuronal loss in a human neurodegenerative disease. As a quantitative method, HRMAS 1HMRS has potential applications in experimental and clinical neuropathologic investigations. It should also provide a rational basis for the interpretation of in vivo 1HMRS studies of human neurological disorders.

Amino Acids↗
PubMed1976

Pruritus of pregnancy and jaundice induced by oral contraceptives.

This article presents a young girl who developed jaundice while on oral contraceptives. A most significant feature in this particular patient's history was the severe pruritus she developed during a previous gestation. This combination of events should alert physicians to the possible diagnosis. Oral contraceptives should be prescribed to such a patient with great caution.

Adolescent↗