Relationship between radiation injury and Alzheimer-related neurodegenerative changes.

The relationship between radiation injury and other neurodegenerative changes such as the formation of neuritic or diffuse plaques and tangles have received little attention in the literature. In the current study, archival tissue was examined from 485 patients with the diagnosis of either a primary or metastatic brain tumor, who had received radiation therapy between the initial and subsequent pathological study (either surgical or autopsy). Of those cases, 20 were identified that also contained cerebral cortex in both specimens. Sections were stained with the modified Bielschowsky technique and immunohistochemical preparations for beta-amyloid. Contrary to previous reports, the present study did not identify neurodegenerative changes typical of Alzheimer's disease as a consequence of radiation therapy.

Neuropathology of the brain and spinal cord in human West Nile virus infection.

OBJECTIVE: To describe the histopathology of the brain and spinal cord in human West Nile virus (WNV) infection. MATERIALS AND METHODS: Single case report, including premortem clinical and laboratory findings, and autopsy. RESULTS: An 83-year-old female presented with acute confusion, high fevers, dysarthria and generalized subjective weakness, with decreased deep tendon reflexes and weakness on physical examination. Electromyography showed evidence of a sensorimotor axonal polyneuropathy of the right-sided extremities. She became ventilator-dependent and died after a 2-week ICU stay, following withdrawal of life support. WNV infection was confirmed premortem by detection of IgM antibodies from serum and CSF and postmortem by RT-PCR from brain tissue. Examination of the brain parenchyma showed scattered microglial aggregates accompanied by perivascular chronic inflammation. The leptomeninges showed focal lymphocytic infiltrates. Examination of the spinal cord showed lymphocytic infiltrates in nerve roots and within the cord proper, with focal microglial nodules and neuronophagia in the ventral horns. Special stains were negative for a demyelinating process. General autopsy revealed only emphysema and atelectasis. CONCLUSIONS: The findings in this case suggest direct viral infection of the spinal cord and nerve roots as the mechanism of the flaccid paralysis often observed in patients infected with WNV. Findings are reviewed in comparison with other reports of neuropathologic findings in human WNV infection.

Primary colon cancer without gross mucosal tumor: unusual presentation of a common malignancy.

Colon cancer typically arises in the colonic lumen, allowing for endoscopic detection of cancerous and premalignant lesions. In the case presented, a 73-year-old man with iron deficiency anemia had two colonoscopies showing only diverticula and internal hemorrhoids. Three years later, when the patient complained of dull, intermittent lower abdominal pain, a third colonoscopy identified diverticula, three adenomatous polyps, and no other abnormality. Computed tomography (CT) of the abdomen revealed a 5 cm x 6 cm pericolic fluid collection, which was later found to communicate with the sigmoid colon. The surgical specimen from a partial colectomy contained a distal sigmoid perforation with a 2.5 cm moderately differentiated adenocarcinoma in the underlying submucosal tissue. There was no gross intraluminal tumor. Histopathology, including immunohistochemistry, was consistent with colonic adenocarcinoma. Primary colon cancer grossly sparing the mucosa is an unusual presentation for this common malignancy.

Acquisition of a complex place task in rats with selective ibotenate lesions of hippocampal formation: combined lesions of subiculum and entorhinal cortex versus hippocampus.

The effects of isolating the hippocampus from its neocortical inputs and outputs by damaging the deep layers of entorhinal cortex and subiculum were compared with direct removal of the hippocampus using acquisition of a complex radial maze task. A series of eight problems (four out of eight arms being correct) were learned under either massed (45 s) or distributed (10 min) practice conditions, thus varying contextual information. Performance of rats with subiculum/entorhinal cortex lesions was similar to that of controls in all aspects of the radial maze task; whereas animals with hippocampal lesions were impaired on nearly all dependent measures. Although the effects of varying the intertrial interval were generally small, distributed practice did serve to facilitate the performance of hippocampal rats in terms of working memory. These findings are discussed as they related to recent theorizing in the area.