Polyamines have various roles in cortical development. We examined the ontogenic changes in ornithine decarboxylase (ODC), the rate-limiting enzyme of polyamine biosynthesis, in cerebral cortices of normal and hydrocephalic rats. Both biochemical and immunohistochemical examinations revealed increased ODC protein and enzyme activity during the perinatal period. Apical dendrites of developing neuroblasts migrating from the superficial layer of cortical plate showed intense ODC immunoreactivity. Once they had settled at their final destination, ODC immunoreactivity weakened. Both ODC immunoreactivity and enzyme activity reached very low levels after completion of layer formation of cortex. The enzyme activity of ODC in hydrocephalic cortices exceeded that in normal cortex during the perinatal periods. ODC was rather overexpressed, but no characteristic distribution was observed in the hydrocephalic cortex. These findings indicate the participation of polyamines in the cortical development, especially in the layer formation. The overexpression of ODC in hydrocephalus appears to promote development despite increased hydrostatic pressure.

Animals↗

PubMedDate not supplied

Ornithine decarboxylase in developing brain of hydrocephalic rats. Effects of shunt operation.

We examined the changes in ornithine decarboxylase (ODC) immunoreactivity in the hydrocephalic cerebral cortex of HTX rats after decompression by shunt operation. The ODC immunoreactivity reached a very low level after the completion of cortical layer formation, and only faint staining was found on postnatal day (Pd) 11. The ODC immunoreactivity re-appeared after the shunt operation when the operation was done in the early days of life: the ODC immunoreactivity was first found on day 2 after shunting and persisted until day 8 after shunting. However, this was not apparent when the operation was not performed until Pd 14. The re-expression of ODC in hydrocephalic brain after shunting appears to cause resumption of the developmental process by relieving neurons from increased hydrostatic pressure. The dependence of ODC re-expression on the timing of the operation indicates that there may be a period of neocortical decompression that is critical for effective compensatory development, so that when delayed, decompression fails to re-activate the ODC-dependent development.

Animals↗

PubMedDate not supplied

Sequential MRI findings in a patient with a germ cell tumor in the basal ganglia.

Serial changes of MRI scanning of an 11-year-old boy with hemiparesis due to a germ cell tumor in the basal ganglia are presented. Initial brain MRI T1-weighted images revealed a subtle mixed signal intensity lesion at left anterior and posterior limbs of the internal capsule. This lesion was not enhanced with Gd-DTPA, however, T2-weighted images showed a misty high signal intensity lesion in the same region. The MR images also showed hemiatrophy of the left basal ganglia. Histologic examination of biopsy specimens of the tumor revealed an embryonal carcinoma. The patient was treated with chemotherapy with subsequent improvement in the hemiparesis. Our case suggests that germ cell tumors must be considered in the differential disorders of lesions in the ipsilateral hemiatrophic basal ganglia in pediatric patients with hemiparesis.

Basal Ganglia↗

PubMedDate not supplied

Effect of contrast material, hypercapnia, hyperventilation, hypertonic glucose and papaverine on the diameter of the cerebral arteries. Angiographic determination in man.

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Angiography↗

PubMedDate not supplied

Cystic cavernous angioma in an infant: CT features.

A cavernous angioma with the unusual CT features of a large cyst and a small nodule was found in an 8-month-old girl. The cyst contained crystal-clear fluid, and a previous hemorrhagic event was histologically confirmed.

Brain Neoplasms↗

PubMedDate not supplied

Thoracic meningocele in neurofibromatosis: CT and MR findings.

A case of lateral intrathoracic meningocele incidentally found in association with neurofibromatosis Type 1 is presented. Magnetic resonance imaging proved most valuable in diagnosis.

Female↗

PubMedDate not supplied

Metastatic adenocarcinoma presenting as a homogeneously high density mass on CT.

We report a case of metastatic adenocarcinoma to the brain that appeared as a homogeneously hyperdense mass on CT. The lesion was initially diagnosed as an intracerebral hematoma. On serial CT scans, the high density lesion progressively enlarged. Pathology showed coagulation necrosis without hemorrhage or calcification. Analysis of the tumor revealed elevation of the protein content relative to the normal brain. We conclude that the high CT attenuation was due to the elevated protein content.

Adenocarcinoma↗

PubMedDate not supplied

Diffusion-weighted MR in experimental sustained seizures elicited with kainic acid.

PURPOSE: To investigate the early changes in diffusion-weighted MR images in the sustained limbic seizures. METHOD: Intraperitoneal injection of kainic acid was used to induce sustained limbic seizures in seven rats. The animals were investigated with serial 2.0-T MR imaging beginning immediately after kainic acid-induced seizures, and at 24 hours, 3 days, and 7 days after the kainic acid injection. Diffusion-weighted spin-echo and T2-weighted images and apparent diffusion coefficients were sequentially assessed and compared with histologic changes. The results were compared with eight control animals given buffered saline intraperitoneally. RESULTS: Diffusion-weighted MR images revealed an increase in signal intensity bilaterally in the amygdala and the piriform cortices immediately after the sustained seizures, whereas T2-weighted images did not show changes in signal intensity at this time. Both diffusion-weighted and T2-weighted images showed marked increase in signal intensities in these same areas 24 hours after kainic acid injection. The apparent diffusion coefficient values were significantly lower in the area of the amygdala and the piriform cortex immediately after and lower again 24 hours after the sustained seizures. The area of hyperintensity in diffusion-weighted images was concordant with the histologic distribution of neuronal pyknosis and neuropile vacuolation. CONCLUSION: Diffusion-weighted MR revealed focal abnormalities in the limbic system after 1 hour of sustained seizures induced with kainic acid, before changes on T2-weighted imaging. Diffusion-weighted MR is a potential method for studying the mechanisms of brain damage caused by sustained seizures.

Amygdala↗