kaolinite and Brain-Diseases

A parenchymal brain granuloma is the final consequence of a localized inflammatory reaction against an infectious agent, particularly parasites. In humans, these lesions are frequent causes of epilepsy. We studied the pattern of seizures induced by pentylenetetrazol (PTZ) in cats with a chronic granuloma induced 1 year earlier by injection of silicates into the brain amygdala. Compared with controls, the seizure threshold to myoclonic seizures was significantly decreased in cats with granuloma, while the threshold for tonic-clonic seizures was not altered. Thus, the difference in PTZ doses between the initial and final components of the seizure became significantly enlarged (P < 0.001). Our results indicate that a granulomatous lesion in amygdala facilitates the generation and propagation of myoclonic seizures, whereas other components of PTZ-induced seizures are not affected.

Topics: Amygdala; Animals; Brain Diseases; Cats; Granuloma; Kaolin; Male; Pentylenetetrazole; Seizures; Tomography, X-Ray Computed

We studied the origin of the epithelioid cells (macrophages) observed in the rat brain in response to the intracisternal injection of kaolin. The rats, two days of age, were used. The animals were killed after thirteen weeks following cisternal injection of kaolin. Massive epithelioid cell-nodes with multifocal necrosis were seen in the subarachnoid space of the cerebellum, in the cerebellar parenchyma and in the fourth ventricle. They were also present in the choroid plexus. The papillary epithelioid cell-nodes were observed onto the aqueduct of Sylvius, the third and lateral ventricles. These were associated with the proliferation of the adventitia of the blood vessel in the subependymal white matter. This suggested that the vascular adventitia played a role for a formation of the epithelioid cell-node in this case. The epithelioid cell was negative in silver-stained preparation. This indicated that microglia was not a source of the epithelioid cell. Reticulin fibers were moderately increased in the lesions. The epithelioid cells phagocytized kaolin granules and gave a strong PAS-positive reaction. However, it seemed that the PAS-positive materials were not identical to the kaolin granules. A rich accumulation of apparently extra- and intracellular kaolin deposits stained metachromatically violet with toluidine blue was seen in the necrotic areas. A large number of the degenerated cells containing kaolin deposits was found especially in the marginal zone of the necrotic areas. Granulation tissue with the amount of spindle-form cells and collagen fibers was also observed in the subarachnoid space. The granulation tissue was formed by hyperplasia of fibroblasts following the proliferation of the epithelioid cells and their necrotic processes.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Brain Diseases; Cisterna Magna; Disease Models, Animal; Epithelium; Granuloma; Injections; Kaolin; Macrophages; Meningoencephalitis; Necrosis; Rats; Rats, Inbred Strains

The present report describes SEM observations on a variety of subjects, such as the walls of cerebral ventricles under pathological circumstances (hydrocephalus) as well as the surface morphology of abnormal cavities like arachnoid cysts and subdural hematomas. In the human specimens with hydrocephalus the changes consisted of degeneration of ependymal cilia, progressing to denudation of the ependyma while rupture of the ependymal layer was also seen. In experimental animals where the hydrocephalus was induced by agents (presumably irritant to the tissue), the presence of reactive supraependymal cells was observed next to the manifestations of ependymal degeneration. With the SEM the wall of arachnoid cysts showed numerous microvilli of stubby appearance with interspersed projections of diverse shape in the individual cases. SEM may aid in the diagnosis of arachnoid cysts, particularly in differentiating them from traumatic leptomeningeal cysts.

Topics: Animals; Biopsy; Brain; Brain Diseases; Cerebral Ventricles; Choroid Plexus; Hematoma, Subdural; Humans; Hydrocephalus; Kaolin; Meningeal Neoplasms; Meningioma; Microscopy, Electron, Scanning; Microvilli; Rats; Silicones

Walker tumor cells and carcinogens were implanted into the brains of rats and L1210, P388 and Ehrlich ascites tumors, in addition to inflammatory agents and hydrocarbons, injected cortically into mice. Behavioral changes were followed in such animals by several psychological criteria, a discriminated lever-press task in rats and an exploratory task, the poke test, in rats and mice. An activity wheel was also employed for further amplification of mouse behavior. No definite changes could be discerned by these tests between rats bearing tumor or carcinogen and the respective controls as was also the case with levels of activity in the mouse. In marked contrast, mice administered tumors or kaolin cortically demonstrated significant reductions in the mean number of pokes, especially with the higher numbers of cells injected and where neurological symptoms were evident. Behavioral changes, if any, were minimal in mice with cortically implanted carcinogens.

Topics: Animals; Behavior, Animal; Brain Diseases; Brain Neoplasms; Carcinogens; Carcinoma 256, Walker; Carcinoma, Ehrlich Tumor; Cerebral Cortex; Haplorhini; Hydrocarbons; Inflammation; Kaolin; Leukemia L1210; Male; Mice; Neoplasm Transplantation; Pectins; Rats; Talc

Topics: Adolescent; Arnold-Chiari Malformation; Brain Diseases; Cerebral Ventriculography; Cerebrospinal Fluid Shunts; Child; Child, Preschool; Disease Models, Animal; Female; Humans; Hydrocephalus; Intracranial Pressure; Kaolin; Male; Skull; Synostosis

Topics: Blood Coagulation Disorders; Brain Diseases; Disseminated Intravascular Coagulation; Female; Humans; Injections, Intravenous; Kaolin; Substance-Related Disorders