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Biomedical subjects

A E George

Publications and source records attributed to A E George.

At least 19 recordsLinked to original sources
PubMed1995

The differential diagnosis of Alzheimer's disease. Cerebral atrophy versus normal pressure hydrocephalus.

This article summarizes the neuroradiology of Alzheimer's disease (AD) and details the radiologic features that permit the identification of patients with normal pressure hydrocephalus (NPH). Patients with presumed AD show a characteristic atrophy pattern with specific involvement of the temporal lobes and hippocampus. These findings have prognostic implications. Patients with NPH typically show severe motoric and gait deficits and initially mild cognitive impairment. Marked improvement is shown in select patients after ventricular shunting.

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PubMed1995

Nonspecific leukoencephalopathy associated with aging.

With advancing age, the periventricular and subcortical white matter becomes susceptible to a heterogeneous assortment of tissue alterations that cannot be easily categorized in terms of traditionally defined neuropathologic disease. These alterations, which appear radiolucent on CT and hyperintense on T2-weighted MR imaging, are more common in patients with chronic hypertension and perhaps other microvascular arteriosclerotic risk factors. Examination of the affected tissue reveals a spectrum of histologic change that is graded with respect to pathologic severity. The majority of the alterations are of low histopathologic grade and exert minimal clinical effects. Frequently observed microscopic changes include dilated perivascular (Virchow-Robin) spaces, mild demyelination, gliosis, and diffuse regions neuropil vacuolation. Associated clinical abnormalities, when present, are usually confined to deficits of attention, mental processing speed, and psychomotor control. These deficits may often be demonstrable only through neuropsychologic testing. There is some evidence that the cognitive symptoms of AD may be exacerbated by the concomitant presence of these white matter alterations, but an etiologic link between AD and radiographically detectible white matter changes remains speculative. Occasionally, histologically severe white matter lesions may occur that result in dementia and focal neurologic impairment. These lesions are characterized by extensive arteriosclerosis, diffuse white matter necrosis, and lacunar infarction; affected patients may receive a diagnosis of Binswanger's disease or subcortical arteriosclerotic encephalopathy. Nevertheless, severe ischemic white matter pathology of this type is uncommon as an explanation for serious neurologic dysfunction, and clinicians must carefully weigh other categories of neuropathology before making a diagnosis of Binswanger's disease. Alternative diagnostic considerations include neurodegenerative illnesses such as AD, cerebral infarction, neoplasm, and other forms of white matter pathology such as those due to infection, inflammation, a primary demyelinative condition, or metabolic leukodystrophy.

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PubMed1992

Topography of cross-sectional and longitudinal glucose metabolic deficits in Alzheimer's disease. Pathophysiologic implications.

Positron emission tomographic studies of cerebral glucose metabolism have shown high diagnostic specificity in distinguishing among the degenerative dementias and differentiating between Alzheimer's disease (AD) and normal aging. The current investigation was undertaken to characterize the regional glucose metabolic deficits in AD, using cross-sectional and longitudinal study designs. All subjects met the National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria for AD (n = 45) or were normal (n = 20), and the AD subjects were subdivided into incipient and mild AD and moderate plus moderately severe subgroups based on the Global Deterioration Scale. The subjects underwent a non-contrast computed tomographic scan and a positron emission tomographic (PETT VI) scan. The AD subjects (n = 14) and normal control subjects (n = 15) received evaluations 2 to 3 years after baseline study. The brain regions that show glucose metabolic deficits cross-sectionally (temporal and parietal association areas, with lesser degrees of deficit in subcortical gray matter structures), over the stages of AD, also show further deficits longitudinally within the same AD subjects. The reduction in glucose metabolism is greater than would be expected from the degree of brain atrophy. The glucose metabolic deficits are discussed in the context of neuropathologic findings and neurotransmitter deficits in AD.

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PubMed1991

Alzheimer disease: measuring loss of cerebral gray matter with MR imaging.

The distributions of the cerebral gray matter, the white matter, and the intracranial cerebrospinal fluid (CSF) were measured in 14 patients with Alzheimer disease (AD) and in 14 healthy control subjects. The measurements, derived from two specifically designed magnetic resonance inversion-recovery sequences, compensate for partial signal averaging. The percentage of the gray matter in the brains of AD patients (44.9% +/- 4.4) was significantly lower than in control subjects (50.2% +/- 3.2). The most significant reduction (P less than .001) occurred in the temporal lobes (13.8%) and a central region (12.8); the reduction in frontal lobe (11.2%) and occipital lobe (9.2%) was also statistically significant (P less than .01). There was an increase in the CSF volume in the temporal, occipital, and frontal regions; no region showed a significant difference in the white matter content. The findings of diffuse changes and temporal lobe involvement in AD are consistent with pathologic observations of cortical cell loss.

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PubMed1990

Effect of temperature and pH on survival of Listeria monocytogenes in coleslaw.

The survival and growth of Listeria monocytogenes in fresh coleslaw, pH 3.9, and in coleslaw adjusted to pH 4.0, 5.0, 6.0 or 7.0 before inoculation was studied at three temperatures (4, 15 and 25 degrees C). L. monocytogenes was not detectable after 5 days incubation in fresh coleslaw nor in coleslaw adjusted to pH 4.0. Coleslaw at pH 5.0 was also inhibitory to L. monocytogenes at all three temperatures studied. A decline in viable numbers of L. monocytogenes in coleslaw at pH 6.0 occurred at 4 degrees C and at 15 degrees C, whereas at 25 degrees C the viable count of L. monocytogenes increased initially and remained high after incubation for 25 days. L. monocytogenes grew rapidly in coleslaw at pH 7.0 at all three temperatures studied, followed by an equally rapid decline in viable count.

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PubMed1989

Alzheimer's disease: longitudinal CT studies of ventricular change.

A 3-year longitudinal study was conducted with 50 Alzheimer's disease patients and 45 elderly control subjects. All study participants received an extensive evaluation that included brain CT at baseline and follow-up. Quantitation of ventricular size, using both linear and volume methods, revealed highly significant cross-sectional and longitudinal differences between the Alzheimer patients and control subjects. Specifically, the annual rate of change in ventricular volume was approximately 9% in the Alzheimer patients and approximately 2% in the controls. The presence of age-related white matter lesions had no effect on the clinical course of the patients or on the changes in ventricular size. Among the Alzheimer patients, the rate of clinical decline was strongly related to the rate of change in ventricular size. Baseline ventricular measurements were of no value in predicting the subsequent rate of clinical deterioration or ventricular enlargement. The results suggest that changes in ventricular size closely reflect the clinical changes in Alzheimer patients.

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