Frances K. Conley

Toxoplasma gondii infection of the central nervous system: Use of the peroxidase-antiperoxidase method to demonstrate toxoplasma in formalin fixed, paraffin embedded tissue sections

The peroxidase-antiperoxidase immunohistochemical technique was employed to stain formalin fixed, paraffin embedded tissue sections from three cases of encephalitis caused by Toxoplasma gondii. We studied two cases of congenital infection and one case of acquired toxoplasmosis occurring in an immunocompromised host. The peroxidase-antiperoxidase method was exquisitely sensitive and highly specific and stained both the encysted and tachyzoite forms of the organism, as well as allowing for easy identification of infected cells. In two cases of necrotizing encephalitis--one congenital, the other acquired--widespread dissemination of the Toxoplasma organism throughout the neural parenchyma was visualized using the peroxidase-antiperoxidase stain. Brain biopsy material that had been obtained eight days prior to death in the case of adult acquired toxoplasmosis did not contain any of the characteristic tissue cysts and was not diagnostic for toxoplasmosis by conventional staining techniques. However, peroxidase-antiperoxidase staining of tissue sections from this biopsy unequivocally demonstrated both free tachyzoites and multiple infected cells. Further application of the peroxidase-antiperoxidase method should increase our understanding of the pathology and pathogenesis of toxoplasmic encephalitis as well as allowing timely diagnosis in cases presenting with neurologic symptomatology.

Outbreak of central-nervous-system toxoplasmosis in Western Europe and North America

Acute encephalitis caused by Toxoplasma gondii was diagnosed in ten patients in Belgium, the U.S.A., and Canada. None had underlying conditions usually associated with toxoplasmosis. Three had evidence of extraneural infection at necropsy. Nine patients died. Only two of the patients had a history of homosexuality, and one was a heroin addict. Five were Haitian, and four of them had lived in North America for 2-5 years. Eight of the patients had pronounced lymphopenia. Diagnosis of toxoplasmosis was hampered by a lack of suspicion that Toxoplasma could be the agent causing necrotising encephalitis in the non-immunocompromised host, the protean manifestations of the encephalitis, and a lack of a specific antibody response. The large number of cases appearing in western Europe and North America emphasise the necessity of including toxoplasmosis in the differential diagnosis of encephalitis of unknown aetiology.

Cell adhesion molecules on vessels during inflammation in the mouse central nervous system.

The expression of endothelial cell adhesion molecules (CAMs) in the central nervous system (CNS) of the mouse was examined during an inflammation induced by intracerebral injection of killed Corynebacterium parvum (C. parvum). We showed that injection of killed C. parvum produced an inflammatory cellular infiltrate limited to the injected brain hemisphere. However, the upregulation of ICAM-1 and VCAM-1 on brain endothelium occurred starting 2 days after C. parvum injection throughout the entire CNS and was not restricted to vessels surrounded by a cellular infiltrate. In contrast to the systemic upregulation of ICAM-1 and VCAM-1, cerebral vessels located in the center of the cellular infiltrate started to express the MECA-32 antigen, suggesting an altered functional status of the endothelial cells, as this antigen is suppressed during development of the blood-brain barrier (BBB). Binding assays performed on frozen sections of inflamed brains are consistent with an important role for endothelial VCAM-1 in the recruitment of lymphocytes during inflammation in the CNS of the mouse.

Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems II. Electron microscopy observations

SummaryExplants from seven nerve sheath tumors (four cranial and three spinal) induced in rats by transplacental ethylnitrosourea were grown on collagen-coated coverslips and in organ culture systems, using sponge foam matrices and Millipore filter platforms. Their sequential morphological features in vitro were compared to those of a human acoustic Schwannoma maintained in similar culture systems. The original experimental tumors were either undifferentiated or poorly differentiated malignant Schwannomas. In cultures on collagen-coated coverslips the explants demonstrated cellular features that were considerably more anaplastic than those of the human acoustic Schwannoma. On the other hand, in organ culture systems, in which viable cultures were maintained up to 82 days, many of the experimental tumor explants exhibited progressive differentiation, with nuclear palisading, increasing whorl formation and abundant reticulin fibers, and their pattern of histological organization came therefore closely to resemble that of the cultured acoustic Schwannoma. Unlike the latter, however, the cultured experimental tumors infiltrated the sponge foam matrices, a feature that mimicked the invasive character of the original tumors in vivo. Included normal ganglion cells remained demonstrable in the cultures up to 69 days in vitro.

Epidermoid tumors involving the fourth ventricle.

The case histories of three patients with epidermoid tumors of the 4th ventricle treated by surgical excision are presented. All three cases exhibited a prolonged latent period from the onset of symptoms to the final diagnosis. Despite the strategic location and enormous size of all three tumors, only one of the patients had significant hydrocephalus. The radiographic diagnosis and differential diagnosis of epidermoid tumors are discussed.

Studies on experimental malignant nerve sheath tumors maintained in tissue and organ culture systems

SummaryFour melanin pigment-containing intracranial tumors were found in three Long-Evans rats in the course of experimental oncogenesis by transplacental ethylnitrosourea (ENU). One of them was a leptomeningeal melanoma. Aside from the presence of scattered melanin-pigmented cells, the other three had the typical histological features of ENU-induced malignant nerve sheath tumors. Two of the three tumors were studied by electron microscopy and in tissue and organ culture systems. One of them demonstrated progressive melanogenesis in vitro; the other failed to produce more melanin and showed increasing differentiation, with a Schwannoma-like pattern by light microscopy. Melanosomes and premelanosomes were identified in both tumors by electron microscopy; the other fine structural features were those of malignant Schwannomas.These observations are relevant to the controversy on the histogenesis of pigmented nerve sheath tumors occasionally encountered in man and on the relationship of these tumors to pigmented nevi. The findings in the present study support the view of Masson that neoplastic nerve sheath cells are capable of melanogenesis.

Toward a More Perfect World -- Eliminating Sexual Discrimination in Academic Medicine

The modest study by Komaromy et al.1 in this issue of the Journal usefully reminds the medical world that not only verbal discrimination2 but also more blatant forms of sexual harassment are remark...

Decompression of Lumbar Spinal Stenosis and Stabilization with Knodt Rods in the Elderly Patient

We present a series of 25 elderly patients who exhibited signs and symptoms of neurogenic claudication and who were found to have one or two levels of spinal stenosis. At the time of decompressive surgery, excessive movement was found at the stenotic levels, so a simple stabilization procedure was performed using Knodt rods and a facet fusion. The expectation was that spine fixation would decrease the amount of postoperative back pain, which can be a result of continued abnormal mobility. All of the patients have been followed for 2 or more years. This elderly group of individuals tolerated surgery well, and long-term results were good.

Effect of radiation therapy on hemangioblastoma: a case report and review of the literature.

A case of medullary hemangioblastoma treated with radiation and operation is presented. After radiation a 55% decrease in the volume of the vascular portion of the tumor was documented by angiograms. Also, there were planes of dissection between the tumor and the dorsal medulla that had not been appreciated at exploratory operation before radiation. Total resection of the tumor was accomplished using hypothermia and cardiac standstill. The literature detailing the effects of radiation on hemangioblastoma is reviewed. (Neurosurgery, 6: 82--86, 1980)

Effect of Radiation Therapy on HemangioblastomaA Case Report and Review of the Literature

A case of medullary hemangioblastoma treated with radiation and operation is presented. After radiation a 55% decrease in the volume of the vascular portion of the tumor was documented by angiograms. Also, there were planes of dissection between the tumor and the dorsal medulla that had not been appreciated at exploratory operation before radiation. Total resection of the tumor was accomplished using hypothermia and cardiac standstill. The literature detailing the effects of radiation on hemangioblastoma is reviewed. (Neurosurgery, 6: 82--86, 1980)