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Biomedical subjects

S A Ellias

Publications and source records attributed to S A Ellias.

6 recordsLinked to original sources
PubMed2000

Transplantation of embryonic porcine mesencephalic tissue in patients with PD.

OBJECTIVE: To assess the safety and the effect on standardized clinical rating measures of transplanted embryonic porcine ventral mesencephalic (VM) tissue in advanced PD. METHODS: Twelve patients with idiopathic PD underwent unilateral implantation of embryonic porcine VM tissue; six received cyclosporine immunosuppression and six received tissue treated with a monoclonal antibody directed against major histocompatibility complex class I. Patients were followed for 12 months and assessed by clinical examination, MRI, and 18F-levodopa PET. Porcine endogenous retrovirus testing was conducted by PCR-based method on peripheral blood mononuclear cells. RESULTS: Cell implantation occurred without serious adverse events in all patients. Cultures were negative for bacterial and unknown viral contamination. No porcine endogenous retrovirus DNA sequences were found. MRI demonstrated cannula tracts within the putamen and caudate, with minimal or no edema and no mass effect at the transplant sites. In the medication-off state, total Unified Parkinson's Disease Rating Scale scores improved 19% (p = 0.01). Three patients improved over 30%. There were two patients with improved gait. 18F-levodopa PET failed to show changes on the transplanted side. CONCLUSIONS: Unilateral transplantation of porcine embryonic VM cells into PD patients was well tolerated with no evidence of transmission of porcine endogenous retrovirus. Changes in standardized clinical PD rating measures were variable, similar to the results of the first trials of unilateral human embryonic allografts that transplanted small amounts of tissue.

Aged↗
PubMed1999

Tremor frequency patterns in mercury vapor exposure, compared with early Parkinson's disease and essential tremor.

A new portable tremometer allows determination of tremor intensities at different tremor frequencies. Based on past studies, two tremor frequency windows of similar size were chosen at 3.0-6.5 Hz and 6.6-10.0 Hz to reflect major tremor intensities in Parkinson's disease and mercury vapor poisoning, respectively. In 81 healthy controls, total tremor intensity was higher for the preferred hand and depended on age. Ten patients treated for Parkinson's disease showed substantially increased tremor intensity, especially within the low-frequency window. This pattern was also apparent in 14 patients with de novo Parkinson's disease whose overall tremor intensity was only mildly elevated. In contrast, ten patients with essential tremor had peak frequencies in both windows, and some patients had increased tremor on one side only. Sixty-three Brazilian gold traders exposed to mercury vapor showed increased tremor predominantly in the high-frequency window. Three of the gold traders had a narrower tremor peak at frequencies of 7-8 Hz. While the urine-mercury concentration was significantly associated with the current number of burning sessions per week, it did not correlate with tremor intensities. However, eight traders had a urinary mercury excretion level above 50 microg and at the same time a greatly increased average tremor intensity within the high-frequency window. These patterns were statistically significant for relative tremor intensities, but were less clear when total intensities were used. These observations suggest that the relative distribution of tremor intensities in specific frequency bands may be a valuable supplement to current diagnostic methods for subjects with mercury vapor exposure.

Adult↗
PubMed1995

Quantitative assessment of movement in Alzheimer's disease.

To determine whether bradykinesia in patients with Alzheimer's disease is different from the slowing of movement seen in normal aging, 25 patients with mild to moderately severe Alzheimer's disease and 25 normal controls, matched for age and sex, were studied. The measures of motor performance included two computerized tests of finger tapping, one test of point-to-point arm movements, and one test of gait cadence. Patients performed significantly more slowly than controls on all three types of motor speed measurements, with average decrements of 9% to 19%. Right index finger tapping, right arm point-to-point, and left arm point-to-point tests produced the most significant discrimination of patients from controls. One month test-retest reliability in patients was high for these measures. Bradykinesia measured by these tests was correlated with cognitive tests requiring concentration and executive functions, suggesting a relationship to frontal lobe disease. Bradykinesia in Alzheimer's disease differs quantitatively from the effects of normal aging on movement. Motor function can be reliably measured in Alzheimer's disease patients by simple and rapid tests of tapping speed, which may be useful as functional parameters in studying disease progression and response to pharmacologic intervention.

Aged↗
PubMed1980

The dendritic varicosity: a mechanism for electrically isolating the dendrites of cat retinal amacrine cells?

Amacrine dendritic varicosities from cat retina were reconstructed using serial electron micrographs. Each varicosity contained a synaptic input and a synaptic output, suggesting that they may function as isolated local circuits. A passive steady state electrical model demonstrated that for a given conductance change the varicose dendrite maximizes the local membrane potential and minimizes th distance membrane potential change as compared to other possible dendritic shapes. We, therefore, suggest that the function of the varicosities on amacrine cell dendrites might be to electrically isolate these local input-output circuits.

Animals↗
PubMed1980

Nonequilibrium linear behavior of biological systems. Existence of enzyme-mediated multidimensional inflection points.

The linear phenomenological equations of nonequilibrium thermodynamics are limited theoretically to near equilibrium although a number of biological systems have been shown to exhibit a "linear" relationship between steady-state flows and conjugate thermodynamic forces outside the range of equilibrium. We have found a multidimensional inflection point which can exist well outside the range of equilibrium around with enzyme-catalyzed reactions exhibit "linear" behavior between the logarithm of reactant concentrations and enzyme catalyzed flows. A set of sufficient conditions has been derived which can be applied to any enzyme mechanism to determine whether a multidimensional inflection point exists. The conditions do not appear overly restrictive and may be satisfied by a large variety of coupled enzyme reactions. It is thus possible that the linearity observed in some biological systems may be explained in terms of enzyme operating near this multidimensional point.

Enzymes↗