O-GlcNAcylation regulates breast cancer metastasis via SIRT1 modulation of FOXM1 pathway

Tumors utilize aerobic glycolysis to support growth and invasion. However, the molecular mechanisms that link metabolism with invasion are not well understood. The nutrient sensor O-linked-β-N-acetylglucosamine (O-GlcNAc) transferase (OGT) modifies intracellular proteins with N-acetylglucosamine. Cancers display elevated O-GlcNAcylation and suppression of O-GlcNAcylation inhibits cancer invasion and metastasis. Here, we show that the regulation of cancer invasion by OGT is dependent on the NAD⁺-dependent deacetylase SIRT1. Reducing O-GlcNAcylation elevates SIRT1 levels and activity in an AMPK-dependent manner. Reduced O-GlcNAcylation in cancer cells leads to SIRT1-mediated proteasomal degradation of oncogenic transcription factor FOXM1 in a MEK/ERK-dependent manner. SIRT1 is critical for OGT-mediated regulation of FOXM1 ubiquitination and reducing SIRT1 activity reverses OGT-mediated regulation of FOXM1. Moreover, we show that SIRT1 levels are required for OGT-mediated regulation of invasion and metastasis in breast cancer cells. Thus, O-GlcNAcylation is a central component linking metabolism to invasion and metastasis via a SIRT1/ /FOXM1 axis.

Histopathological observations in the brains of children exposed to inhalational anesthetic agents: a retrospective autopsy-based study

BACKGROUND

Numerous animal models have demonstrated neuronal damage resulting from anesthetic exposure in the developing brain. Studies have shown a relationship between anesthetic exposure and brain hypoxia, neurodegeneration and apoptosis. The relevance of data derived from controlled experimental studies to human neuropathology is a subject of debate. This study compares histopathological findings in post-mortem brain tissue specimens from children with and without exposure to inhalational anesthetic agents.

METHODS

Autopsy reports were reviewed. Patients were divided into exposure and non-exposure groups defined as any procedure involving inhalational anesthetic agents. A retrospective chart review was performed collecting pathological findings of the brain. The autopsy results examined the presence of twelve different histopathological parameters reflecting morphologic changes in thirteen regions of interest in the central nervous system.

RESULTS

Post-mortem neuropathological findings were analyzed. Thirteen different areas were focused upon and changes were categorized into twelve histopathological parameters. Gliosis, which was confirmed by immunohistochemical staining for glial fibrillary acidic protein, was more prevalent in the exposure group (N.=48) compared to the non-exposure group (N.=20) (P<0.05).

CONCLUSION

The role of anesthetic neurotoxicity is not well understood. Numerous animal models have demonstrated neuronal apoptotic changes linked to anesthetic exposure, there is no tangible evidence supporting this relationship in humans. Our analysis demonstrates histopathological brain changes in children with anesthetic exposure not seen in the non-exposed group. Analysis was based on histopathological parameters representative of salient morphological findings of injury, which were encountered in anatomically divergent regions. Gliosis was the only statistically significant finding in post-mortem brain samples of patients who had received anesthetics.

[The role played by calcium in neuronal injury following neonatal hypoxia or convulsions]

AIM

Calcium plays a complex and pivotal role both in neuronal development and function, and in hypoxia/ ischemia-induced cell death. In this paper, we review current concepts of calcium function emphasizing the neonatal period.

DEVELOPMENT

Calcium enters the neuron through glutamate receptors (NMDA and AMPA) located on the neuronal membrane. After hypoxia or seizures, there is a conformational change of the receptors, with increased flow of calcium into the cytoplasm. Cytoplasmatic calcium triggers activation of several free-radical generation pathways, including the nitric oxide pathway, with a deleterious effect upon the neuron. Calcium then enters the neuronal nucleus, through specific receptors on the nuclear membrane. In our experience, hypoxia and neonatal seizures create nuclear membrane dysfunction, increasing the nitric-oxide-dependent flow of calcium into the nucleus. Nuclear calcium increase is critical for genetic transcription, pro-apoptotic gene activation and a cascade of biochemical and molecular events that lead to an increase of caspases and apoptotic neuronal death.

CONCLUSIONS

Calcium has a crucial role in neuronal damage after neonatal hypoxia or seizures. A better knowledge of the pathogenic mechanisms that lead to neuronal damage after neonatal hypoxia or seizures will assist in future development of efficacious neuroprotective therapies.

[Cerebrovascular disorders in preterm neonates]

AIM

To review the etiology, pathogenesis, clinical manifestations, diagnosis and treatment of cerebrovascular disorders (CVD) in preterm neonates.

DEVELOPMENT

The germinal matrix-intraventricular hemorrhage (GM-IVH) is the most frequent intracranial hemorrhage. The pathogenesis includes intravascular, vascular and extravascular factors. The neuropathologic lesion is the hemorrhage within the subependymal GM. There are four degrees of severity. Clinical manifestations include three syndromes: catastrophic, saltatory and silent. Treatment is prophylactic. Periventricular hemorrhagic infarct is of venous origin, might be associated to GM-IVH and is difficult to differentiate from periventricular leukomalacia (PVL). Cerebellar hemorrhage frequency increases with decreasing gestational age. It may be asymptomatic or manifest with a non-specific neurologic picture. PVL is the most important ischemic lesion. Its pathogenesis includes anatomic, physiologic, maturational, biochemical, infectious and immunologic factors. The neuropathologic lesion is focal necrosis in the terminal distribution of the long penetrating arteries. Treatment is prophylactic. Other ischemic lesions are ischemic arterial infarct, cerebellar infarct, telencephalic leukoencephalopathy and pontosubicular necrosis. CVD diagnostic tests include cerebral ultrasound, computed tomography, magnetic resonance imaging and spectroscopy and electroencephalogram. Mortality of some CVD is high and some others are associated with a high risk of cerebral palsy and cognitive deficits.

CONCLUSION

CVD are common in preterm neonates and represent an important cause of neurologic disease in the child.

Hypoxia-induced caspase-3 activation and DNA fragmentation in cortical neurons of newborn piglets: role of nitric oxide

Hypoxia results in generation of nitric oxide (NO) free radicals, activation of caspase-3, and genomic DNA fragmentation. The present study tests the hypothesis that hypoxia-induced caspase-3 activation and DNA fragmentation are nitric oxide mediated. Studies were conducted in newborn piglets, divided into normoxic (n = 5), hypoxic (n = 5), and hypoxic-7-NINA (n = 6). Hypoxic-7-NINA group received the neuronal nitric oxide synthase inhibitor, 7-Nitroindazole (7-NINA). Caspase-3 activity was determined spectrofluorometrically using enzyme-specific substrates. Sections from the neocortex were stained with an antiserum recognizing active caspase-3. Purified DNA was separated by gel electrophoresis. Administration of 7-NINA resulted in decreased immunoreactivity of caspase-3 (mean LI: 20.2%) as compared to the untreated hypoxia group (mean LI: 57.5%) (P < 0.05). 7-NINA attenuated caspase-3 enzymatic activity as well in comparison to the untreated hypoxia group (P < 0.05). Furthermore, multiple low molecular weight bands corresponding to DNA fragments were present in the hypoxic but not in the normoxic or hypoxic-7-NINA groups. Inhibition of nNOS abates the hypoxia-induced increase in active caspase-3 immunoreactivity, as well as enzymatic activity in cortical neurons, and DNA fragmentation in brain homogenates. We conclude that the coordinate increase of capase-3 activity and fragmentation of nuclear DNA in the hypoxic newborn piglet brain are NO mediated.

Cerebellar hypoplasia with heterotopic purkinje cells in the molecular layer and preservation of the granule layers associated with severe encephalopathy. A new entity?

We present the case of an infant girl, born to first cousins, with a clinical phenotype consisting of microcephaly, hypotonia, strabismus and severe psychomotor retardation. Magnetic resonance imaging (MRI) showed global cerebellar atrophy involving the vermis and both hemispheres. The patient's serum transferrin levels were consistently unremarkable. Cerebellar biopsy, performed at 13 months of age, revealed heterotopic Purkinje cells in the molecular layer, but preservation of the external and internal granular layers. To our knowledge, this histological pattern of cerebellar cortical disorganization has not been described previously. The consanguinity of the parents suggests an autosomal recessive inheritance.

[Cerebral palsy: new pathogenetic concepts]

OBJECTIVE

To review the current knowledge pertaining to the new pathogenetic aspects of cerebral palsy (CP).

DEVELOPMENT

CP is a group of static, heterogeneous clinical syndromes, characterized by abnormal postural mechanisms and motor activities. Its prevalence in industrialized countries is 2 2.5/1000 newborns. CP should be differentiated from certain genetic or metabolic conditions with which it can be mistaken. Some cases of CP have a genetic basis and they are inherited following a mendelian pattern or are determined by specific isolated genes. Recently, the elevation of certain coagulation factors (i.e., Leiden factor V mutation) and cytokines (i.e. interleukins, a tumor necrosis factor) and interferons have been related to CP pathogenesis. Hypocapnia with PaCO2< 35 mmHg represents a risk for periventricular leukomalacia (PVL) in premature infants. PVL pathogenesis is complex and includes a series of mechanisms that interact among them: fetal/maternal infection, immuneinflammatory reaction, prematurity, intraventricular hemorrhage/iron, ischemia/reperfusion, free radical production, maturational sensitivity of oligodendrocytes, and glutamate effect. Neuroradiological and neuropathological data have demonstrated a cortical anatomical substrate for the intellectual deficits associated with PVL in premature infants.

CONCLUSIONS

Current knowledge about CP pathogenesis opens the possibility of early diagnosis and development of new treatments, both therapeutic and preventive.

Presence of oligoclonal T cells in cerebrospinal fluid of a child with multiphasic disseminated encephalomyelitis following hepatitis A virus infection

We have investigated the clonality of beta-chain T-cell receptor (TCR) transcripts from the cerebrospinal fluid (CSF) and peripheral blood from a 7-year old child who developed a multiphasic disseminated encephalomyelitis following an infection with hepatitis A virus. We amplified beta-chain TCR transcripts by nonpalindromic adaptor (NPA)-PCR-Vbeta-specific PCR. TCR transcripts from only five Vbeta families (Vbeta13, Vbeta3, Vbeta17, Vbeta8, and Vbeta20) were detected in CSF. The amplified products were combined, cloned, and sequenced. Sequence analysis revealed in the CSF substantial proportions of identical beta-chain of TCR transcripts, demonstrating oligoclonal populations of T cells. Seventeen of 35 (48%) transcripts were 100% identical, demonstrating a major Vbeta13.3 Dbeta2.1 Jbeta1.3 clonal expansion. Six of 35 (17%) transcripts were also 100% identical, revealing a second Vbeta13 clonal expansion (Vbeta13.1 Dbeta2.1 Jbeta1.2). Clonal expansions were also found within the Vbeta3 family (transcript Vbeta3.1 Dbeta2.1 Jbeta1.5 accounted for 5 of 35 transcripts [14%]) and within the Vbeta20 family (transcript Vbeta20.1 Dbeta1.1 Jbeta2.4 accounted for 3 of 35 transcripts [8%]). These results demonstrate the presence of T-cell oligoclonal expansions in the CSF of this patient following infection with hepatitis A virus. Analysis of the CDR3 motifs revealed that two of the clonally expanded T-cell clones exhibited substantial homology to myelin basic protein-reactive T-cell clones. In contrast, all Vbeta TCR families were expressed in peripheral blood lymphocytes. Oligoclonal expansions of T cells were not detected in the peripheral blood of this patient. It remains to be determined whether these clonally expanded T cells are specific for hepatitis A viral antigen(s) or host central nervous system antigen(s) and whether molecular mimicry between hepatitis A viral protein and a host protein is responsible for demyelinating disease in this patient.

Detection of JC virus DNA sequences and expression of the viral regulatory protein T-antigen in tumors of the central nervous system

JC virus (JCV) is a neurotropic polyomavirus infecting greater than 70% of the human population worldwide during early childhood. Replication of JCV in brains of individuals with impaired immune systems results in the fatal demyelinating disease, progressive multifocal leukoencephalopathy (PML). Furthermore, JCV possesses an oncogenic potential and induces development of various neuroectodermal origin tumors including medulloblastomas and glioblastomas in experimental animals. The oncogenecity of JCV is attributed to the viral early gene product, T-antigen, which has the ability to associate with and functionally inactivate well-studied tumor suppressor proteins including p53 and pRB: The observations from laboratory animal experiments have provided a rationale for examining the presence of the JCV DNA sequence and expression of the viral oncogenic protein in human brain tumors. We have examined 85 clinical specimens from the United Kingdom, Greece, and the United States, representing various human brain tumors including oligodendroglioma, astrocytoma, pilocytic astrocytoma, oligoastrocytoma, anaplastic astrocytoma, anaplastic oligodendroglioma, glioblastoma multiforme, gliomatosis cerebri, gliosarcoma, ependymoma, and subependymoma, for their possible association with JCV. We performed gene amplification techniques using a pair of primers that recognize the JCV DNA sequence, and we demonstrated the presence of the viral early sequence in 49 (69%) of 71 samples. More importantly, our results from immunohistochemistry analysis revealed expression of JCV T-antigen in the nuclei of tumor cells in 28 (32.9%) of 85 tested samples. These observations, along with earlier in vitro and in vivo data on the transforming ability of this human neurotropic virus invite additional studies to re-evaluate the role of JCV in the pathogenesis of human brain tumors.

Aberrant localization of the neuronal class III beta-tubulin in astrocytomas

BACKGROUND

The class III beta-tubulin isotype (betaIII) is widely regarded as a neuronal marker in development and neoplasia. In previous work, we have shown that the expression of betaIII in neuronal/neuroblastic tumors is differentiation dependent. In contrast, the aberrant localization of this isotype in certain nonneuronal neoplasms, such as epithelial neuroendocrine lung tumors, is associated with anaplastic potential.

OBJECTIVE

To test the generality of this observation, we investigated the immunoreactivity profile of betaIII in astrocytomas.

DESIGN

Sixty archival, surgically excised astrocytomas (8 pilocytic astrocytomas, WHO grade 1; 18 diffuse fibrillary astrocytomas, WHO grade 2; 4 anaplastic astrocytomas, WHO grade 3; and 30 glioblastomas, WHO grade 4), were studied by immunohistochemistry using anti-betaIII monoclonal (TuJ1) and polyclonal antibodies. A monoclonal antibody to Ki-67 nuclear antigen (NC-MM1) was used as a marker for cell proliferation. Antibodies to glial fibrillary acidic protein (GFAP) and BM89 synaptic vesicle antigen/synaptophysin were used as glial and neuronal markers, respectively.

RESULTS

The betaIII immunoreactivity was significantly greater in high-grade astrocytomas (anaplastic astrocytomas and glioblastomas; median labeling index [MLI], 35%; interquartile range [IQR], 20%-47%) as compared with diffuse fibrillary astrocytomas (MLI, 4%; IQR, 0.2%-21%) (P <.0001) and was rarely detectable in pilocytic astrocytomas (MLI, 0%; IQR, 0%-0.5%) (P <.0001 vs high-grade astrocytomas; P <.01 vs diffuse fibrillary astrocytomas). A highly significant, grade-dependent relationship was observed between betaIII and Ki-67 labeling and malignancy, but this association was stronger for Ki-67 than for betaIII (betaIII, P <.006; Ki-67, P <.0001). There was co-localization of betaIII and GFAP in neoplastic astrocytes, but no BM89 synaptic vesicle antigen/synaptophysin staining was detected.

CONCLUSIONS

In the context of astrocytic gliomas, betaIII immunoreactivity is associated with an ascending gradient of malignancy and thus may be a useful ancillary diagnostic marker. However, the significance of betaIII-positive phenotypes in diffuse fibrillary astrocytomas with respect to prognostic and predictive value requires further evaluation. Under certain neoplastic conditions, betaIII expression is not neuron specific, calling for a cautious interpretation of betaIII-positive phenotypes in brain tumors.

Acute hypoxia-induced alterations of calbindin-D28k immunoreactivity in cerebellar Purkinje cells of the guinea pig fetus at term

Purkinje cells (PCs) are vulnerable to hypoxic/ischemic insults and rich in calcium and calcium-buffering/sequestering systems, including calcium-binding proteins (CaBPs). Calbindin-D28k is an EF-hand CaBP, which is highly expressed in PCs where it acts primarily as a cellular Ca++ buffer. Elevation of [Ca++] in the cytosol and nuclei of PCs is pivotal in hypoxic/ischemic cell death. We hypothesize that hypoxia results in decreased concentration, or availability of calbindin-D28k in PCs, thereby decreasing their buffering capacity and resulting in increase of intracellular and intranuclear [Ca++]. Cerebellar tissues from normoxic fetuses were compared to fetuses obtained from term pregnant guinea pigs exposed to hypoxia [7% FiO2] for 60 min. The pregnant guinea pigs were either killed upon delivery immediately following hypoxia (Hx0h) or were subsequently allowed to recover for 24 h (Hx24h) or 72 h (Hx72h). Fetal brain hypoxia was documented biochemically by a decrease in brain tissue levels of ATP and phosphocreatine. Compared to normoxic fetuses, there is a predominantly somatodendritic loss or decrease of calbindin-D28k immunohistochemical staining in PCs of Hx0h (p < 0.005), Hx24h (p < 0.05), and Hx72h (p < 0.005) fetuses. Hypoxia-induced alterations of calbindin-D28k immunoreactivity are qualitatively similar at all time points and include a distinctive intranuclear localization in subpopulations of PCs. A similar trend is demonstrated by immunoblotting. Subpopulations of TUNEL+/calbindin-D28k- PCs lacking morphologic features of apoptosis or necrosis are demonstrated in Hx24h and Hx72h fetuses. The present study demonstrates an abrogating effect of perinatal hypoxia on calbindin-D28k immunoreactivity in cerebellar PCs. The perturbation of this Ca++ buffer protein in hypoxia-induced neuronal injury may herald delayed cell death or degeneration.

Differential expression of TGF-beta, IL-2, and other cytokines in the CNS of Theiler's murine encephalomyelitis virus-infected susceptible and resistant strains of mice

Intracranial inoculation of susceptible SJL mice with Theiler's murine encephalomyelitis virus (TMEV) results in biphasic disease consisting of early acute disease, followed by late chronic demyelinating disease, associated with mononuclear infiltrates and demyelinating lesions. In contrast, resistant C57BL/6 (B6) mice develop only early acute disease. We employed cytokine-specific RT-PCR to determine the expression of cytokine transcripts in the CNS of TMEV-infected SJL and B6 mice. During early acute disease, we have found a strong proinflammatory (Th1) cytokine response in the CNS of both TMEV-infected SJL and B6 mice, demonstrated by the expression of transcripts for IFN-gamma, IL-1, IL-6, IL-12p40, and TNF-alpha. At 8 days postinfection (p.i.), TGF-beta1 and TNF-alpha transcripts were present at significantly higher levels (P < 0.01) in the CNS of SJL susceptible mice in comparison to those found in the CNS of B6 mice. Immunohistochemical staining revealed that TGF-beta protein was expressed in leptomeningeal mononuclear inflammatory cell infiltrates in the brain of SJL mice but not in B6 mice, at 8 days p.i. TGF-beta may be responsible for the failure of SJL mice to develop an effective anti-TMEV CTL response. During late chronic demyelinating disease, high levels of proinflammatory Th1 cytokines were found in the CNS of SJL mice, but not B6 mice. Significantly higher levels (P < 0.01) of anti-inflammatory cytokine transcripts (IL-4, IL-5, and IL-10 (Th2 cytokines) and TGF-beta) were found in the spinal cord of TMEV-infected SJL mice with chronic demyelinating disease than in the spinal cord of B6 mice during the same time period (39 or 60 days p.i.). These anti-inflammatory cytokines may contribute to the downregulation of the proinflammatory response in SJL mice. High levels of IL-2 transcripts and protein appeared transiently in the spinal cord of TMEV-infected SJL mice before the onset of demyelinating disease and coincided with an influx of new T cells into the CNS and/or expansion of remaining T cells that have not been eliminated after viral clearance.

Congenital macroglossal angiodysplasia ("Lymphangioendotheliomatosis")

A case of congenital lingual angiodysplasia with macroglossia in a 5-year-old girl is presented. A diffusely enlarged tongue was present at birth and continued to grow as the child aged. It was accompanied by impaired speech, difficulty in eating and breathing, and sleep apnea, necessitating surgical intervention. The fundamental lesion represents a complex vascular malformation of the lymphangioma-hemangioma type, involving extensively the deep musculature of the tongue. Multifocal and multicentric cavernous lymphangioma-like and hemangioma-like areas merge with benign angioendotheliomatous-like foci in a background of variable muscle degeneration and marked fibrosis. Neither a borderline nor an overtly malignant vasoformative neoplasm was present. Because of its distinctively widespread, multicentric intramuscular distribution, this lesion may be construed as a diffuse variant of lingual lymphangioma-hemangioma malformation, closely resembling a previously described case of macroglossal lymphangioendotheliomatosis.

Differential distribution of the neuron-associated class III beta-tubulin in neuroendocrine lung tumors

OBJECTIVE

To study the immunoreactivity profile of the neuron-associated class III beta-tubulin isotype (beta III) in epithelial lung tumors.

DESIGN

One hundred four formalin-fixed, paraffin-embedded primary and metastatic lung cancer specimens were immunostained with an anti-beta III mouse monoclonal antibody (TuJ1) and an anti-beta III affinity-purified rabbit antiserum. Paraffin sections from fetal, infantile, and adult nonneoplastic lung tissues were also examined.

RESULTS

In the fetal airway epithelium, beta III staining is detected transiently in rare Kulchitsky-like cells from lung tissues corresponding to the pseudoglandular and canalicular but not the saccular or alveolar stages of development. beta III is absent in healthy, hyperplastic, metaplastic, and dysplastic airway epithelium of the adult lung. In contrast, beta III is highly expressed in small cell lung cancer, large cell neuroendocrine carcinoma, and in some non-small cell lung cancers, particularly adenocarcinomas. There is no correlation between expression of beta III and generic neuroendocrine markers, such as chromogranin A and/or synaptophysin, in pulmonary adenocarcinomas. Also, focal beta III staining is present in primary and metastatic adenocarcinomas (to the lung) originating in the colon, prostate, and ovary. beta III is expressed to a much lesser extent in atypical carcinoids and is rarely detectable in typical carcinoids and squamous cell carcinomas of the lung. The distribution of beta III in small cell lung cancer and adenocarcinoma metastases to regional lymph nodes and brain approaches 100% of tumor cells, which is substantially greater than in the primary tumors.

CONCLUSIONS

In the context of neuroendocrine lung tumors, beta III immunoreactivity is a molecular signature of high-grade malignant neoplasms (small cell lung cancer and large cell neuroendocrine carcinoma) although its importance in atypical carcinoids must be evaluated further. In addition, beta III may be a useful diagnostic marker in distinguishing between small cell lung cancers and certain non-small cell lung cancers (poorly differentiated squamous cell carcinomas), especially in small biopsy specimens. To our knowledge, beta III is the only tumor biomarker that exhibits a substantially more widespread distribution in poorly differentiated than in better differentiated pulmonary neuroendocrine tumors. However, the significance of beta III phenotypes in non-small cell lung cancer, particularly adenocarcinoma, with respect to neuroendocrine differentiation and prognostic value, requires further evaluation.

Detection of human neurotropic JC virus DNA sequence and expression of the viral oncogenic protein in pediatric medulloblastomas

Medulloblastoma represents greater than 25% of childhood intracranial neoplasms and is considered a highly malignant tumor. This tumor, which arises predominantly in the cerebellar vermis, preferentially affects children between the ages of 5 and 15. Although the etiology of medulloblastomas in humans remains unknown, results from several experiments have indicated that the human neurotropic JC virus (JCV) is able to induce cerebellar neoplasms in rodents that exhibit a phenotype similar to that of human medulloblastomas. JCV is a polyomavirus that is widespread in the human population, with infection occurring most frequently in early childhood. In this study, we have examined the possible association of JCV with human medulloblastomas. By using PCR techniques we demonstrate that 11 of 23 samples of tumor tissue contain DNA sequences corresponding to three different regions of the JCV genome. More importantly, we demonstrate the presence of DNA sequences encoding the N- and C-terminal regions of the JCV oncogenic protein, T antigen, in 11 of 23 samples and the production of T antigen in the nuclei of 4 samples of tumor tissue. These observations provide evidence for a possible association of JCV with human medulloblastomas.

Angiocentric CD3(+) T-cell infiltrates in human immunodeficiency virus type 1-associated central nervous system disease in children

A significant proportion of brain tissue specimens from children with AIDS show evidence of vascular inflammation in the form of transmural and/or perivascular mononuclear-cell infiltrates at autopsy. Previous studies have shown that in contrast to inflammatory lesions observed in human immunodeficiency virus type 1 (HIV-1) encephalitis, in which monocytes/macrophages are the prevailing mononuclear cells, these infiltrates consist mostly of lymphocytes. Perivascular mononuclear-cell infiltrates were found in brain tissue specimens collected at autopsy from five of six children with AIDS and consisted of CD3(+) T cells and equal or greater proportions of CD68(+) monocytes/macrophages. Transmural (including endothelial) mononuclear-cell infiltrates were evident in one patient and comprised predominantly CD3(+) T cells and small or, in certain vessels, approximately equal proportions of CD68(+) monocytes/macrophages. There was a clear preponderance of CD3(+) CD8(+) T cells on the endothelial side of transmural infiltrates. In active lesions of transmural vasculitis, CD3(+) T-cell infiltrates exhibited a distinctive zonal distribution. The majority of CD3(+) cells were also CD8(+) and CD45RO+. Scattered perivascular monocytes/macrophages in foci of florid vasculitis were immunoreactive for the p24 core protein. In contrast to the perivascular space, the intervening brain neuropil was dominated by monocytes/macrophages, microglia, and reactive astrocytes, containing only scant CD3(+) CD8(+) cells. Five of six patients showed evidence of calcific vasculopathy, but only two exhibited HIV-1 encephalitis. One patient had multiple subacute cerebral and brainstem infarcts associated with a widespread, fulminant mononuclear-cell vasculitis. A second patient had an old brain infarct associated with fibrointimal thickening of large leptomeningeal vessels. These infiltrating CD3(+) T cells may be responsible for HIV-1-associated CNS vasculitis and vasculopathy and for endothelial-cell injury and the opening of the blood-brain barrier in children with AIDS.

Experimental aluminum encephalomyelopathy. Relationship to human neurodegenerative disease

Alzheimer's disease has a complex pathogenesis and is a devastating neurologic disorder, predominantly of the elderly human population. Neuronal cell loss and neuritic pathology are a major neuropathologic feature of Alzheimer's disease, but there is no established mechanism to explain the degenerative process. The development of suitable animal systems would be of great value in helping to understand the basic mechanisms underlying the disease. We propose that the aluminum maltolate-treated elderly rabbit is a potentially useful animal system to model Alzheimer's disease neurofibrillary pathology. Details of such an experimental aluminum encephalopathy produced in the rabbit are discussed, along with other aspects of aluminum-induced neurodegeneration.

Cellular distribution of retinoic acid receptor-alpha protein in serous adenocarcinomas of ovarian, tubal, and peritoneal origin: comparison with estrogen receptor status

Retinoids are effective growth modulators of human ovarian carcinoma cell lines. Their effects are mediated by nuclear retinoic acid receptors (RARs) and retinoid X receptors (RXRs), which are transcriptional factors and members of the steroid/thyroid receptor superfamily. To our knowledge, until now, the cellular distribution of RAR proteins in human ovarian tumor specimens is unknown. This study provides new data on the differential cellular localization of RAR alpha protein in 16 serous adenocarcinomas originating from the ovaries, fallopian tubes, and the peritoneum. Using an affinity-purified antiserum specific for RAR alpha and a monoclonal antibody recognizing the full-length estrogen receptor molecule (clone 6F11), we performed immunohistochemistry on frozen tissue sections and examined the relationship between RAR alpha and estrogen receptor protein expression by comparing the percentage of immunostained tumor cells for either receptor. Our findings indicate a strong linear relationship between the percentages of RAR alpha- and estrogen receptor-labeled tumor cells as determined by linear regression analysis (P < 0.005, r = 0.825). A modest inverse relationship was found between the percentage of RAR alpha-positive tumor cells and histological grade, attesting to a differentiation-dependent trend (P < 0.04). No significant relationship was found between RAR alpha-labeled cells and clinical stage (P = 0.139), site of tumor origin (ovaries versus fallopian tubes versus peritoneum) (P = 0.170), and primary versus metastatic lesion (P = 0.561). Thus, serous adenocarcinomas are capable of expressing RAR alpha and estrogen receptor despite high histological grade and advanced stage of neoplastic disease. Compared with the heterogeneous localization of RAR alpha in cancer cells, there was widespread RAR alpha immunoreactivity in tumor-infiltrating lymphocytes, vascular endothelial cells, and stromal fibroblasts, underscoring the value of immunohistochemistry in the accurate determination of RAR/(RXR) content in tumor specimens.

T cells and T-cell cytokine transcripts in the synovial membrane in patients with osteoarthritis

The synovial membrane in osteoarthritis (OA) often exhibits inflammatory infiltrates, but the role of T cells in these infiltrates is not known. T-cell activation antigens were analyzed by immunohistochemistry, and T-cell cytokine transcripts were measured by competitive PCR in synovial membranes from patients with OA and rheumatoid arthritis (RA). Lymphoid cell aggregates, containing primarily CD3+ T lymphocytes, were found in 65% of patients with OA. Mononuclear cells expressing the activation antigens CD69, CD25, CD38, CD43, CD45RO, and HLA class II were present in both patient groups, although in higher numbers in patients with RA. Interleukin 2 (IL-2) transcripts were found in 10 of 18 patients with OA versus 12 of 13 patients with RA (P = 0.03). Gamma interferon (IFN-gamma) transcripts were detected in 9 of 18 patients with OA versus 10 of 13 patients with RA (not significant), whereas IL-10 transcripts were found in nearly all patients. IL-4 and IL-5 were not detected in any patients. The levels of IFN-gamma and IL-2 transcripts, normalized for T-cell number equivalents, were not statistically different between OA and RA, but the levels of IFN-gamma, normalized for total cell number equivalents, were lower in OA than in RA (P = 0.01). Synovial membranes that expressed IL-2 and IFN-gamma transcripts were more likely to have heavier infiltrations of T cells and cells bearing activation markers than synovial membranes that did not express these cytokines. The presence of activated T cells and TH1 cytokine transcripts in chronic joint lesions of patients with OA suggests that T cells contribute to chronic inflammation in a large proportion of these patients.

Inducible nitric oxide synthase and nitrotyrosine are found in monocytes/macrophages and/or astrocytes in acute, but not in chronic, multiple sclerosis

We have examined the localization of inducible nitric oxide synthase (iNOS) and nitrotyrosine (the product of nitration of tyrosine by peroxynitrite, a highly reactive derivative of nitric oxide [NO]) in demyelinating lesions from (i) two young adult patients with acute multiple sclerosis (MS), (ii) a child with MS (consistent with diffuse sclerosis), and (iii) five adult patients with chronic MS. Previous reports have suggested a possible correlation between iNOS, peroxynitrite, related nitrogen-derived oxidants, and the demyelinating processes in MS. We have demonstrated iNOS-immunoreactive cells in both acute-MS and diffuse-sclerosis-type lesions. In acute-MS lesions, iNOS was localized in both monocytes/macrophages and reactive astrocytes. However, foamy (myelin-laden) macrophages and the majority of reactive astrocytes were iNOS negative. In specimens from the childhood MS patient, iNOS protein was present only in a subpopulation of reactive or hypertrophic astrocytes. In contrast, no iNOS staining was detected in chronic-MS lesions. Immunohistochemical staining of acute-MS lesions with an antibody to nitrotyrosine revealed codistribution of iNOS- and nitrotyrosine-positive cells, although nitrotyrosine staining was more widespread in cells of the monocyte/macrophage lineage. In diffuse-sclerosis-type lesions, nitrotyrosine staining was present in hypertrophic astrocytes, whereas it was absent in chronic-MS lesions. These results suggest that NO and nitrogen-derived oxidants may play a role in the initiation of demyelination in acute-MS lesions but not in the later phase of the disease.

Class III beta-tubulin isotype (beta III) in the adrenal medulla: I. Localization in the developing human adrenal medulla

BACKGROUND

The class III beta-tubulin isotype (beta III) is present in neurons of the central and peripheral nervous systems at the earliest stages of morphological differentiation (Easter et al., J Neurosci 13:285-299, 1993; Katsetos et al., J Neuropathol Exp Neurol 52:655-666, 1993). The localization of this protein by immunohistochemistry in the different cell types of the developing human adrenal medulla is described.

METHODS

A mouse monoclonal antibody, TuJ1, was used to localize beta III in formalin-fixed, paraffin-embedded sections from 18 human fetal and adult adrenal glands. Tissue sections were also studied with rabbit antisera recognizing either S-100 protein or glial fibrillary acidic protein (GFAP).

RESULTS

In the developing human adrenal medulla, beta III immunoreactivity was maximal in migrating sympathoadrenal neuroblasts/immature neurons through the end of the second trimester. Clusters of beta III-positive migrating cells, focally forming Homer Wright rosettes, could be identified in a gradient of adrenocortical invasion, i.e., through the permanent cortex and within sinusoids of the fetal cortex en route to the medulla. Outside the adrenal gland, strong beta III staining was observed in peripheral nerve bundles, sympathetic ganglia, and paraganglia at various developmental stages. In adrenal glands from 23 weeks of gestation on, and throughout adult life, all ganglion cells were beta III immunoreactive. In contrast, not all chromaffin cells exhibited beta III staining, but when present, the staining was finely granular. Sustentacular and satellite cells, adrenocortical cells and other mesenchymal elements were betaIII-negative. In sections of fetal and adult adrenal glands, S-100 protein had a sustentacular localization. No GFAP staining was present in sustentacular cells from either fetal or adult adrenals.

CONCLUSIONS

In the developing human adrenal medulla, there is a peak of beta III expression during the active wave of migration of sympathetic neuroblasts. In the mature medulla, beta III is invariably present in adrenergic neurons. However, not all chromaffin-like cells express beta III, suggesting that the presence or absence of this protein identifies two subpopulations of chromaffin cells.

Class III beta-tubulin isotype (beta III) in the adrenal medulla: III. Differential expression of neuronal and glial antigens identifies two distinct populations of neuronal and glial-like (sustentacular) cells in the PC12 rat pheochromocytoma cell line maintained in a Gelfoam matrix system

BACKGROUND

The rat PC12 pheochromocytoma cell line provides an established system for the study of neuronal differentiation. To our knowledge, glial differentiation has not been reported in this cell line.

METHODS

We have studied, by immunohistochemistry and immunoblotting, the presence of neuronal cytoskeletal antigens [class III beta-tubulin isotype (beta III), microtubule associated proteins MAP2, MAP1B and tau, and different neurofilament (NF) protein components], and synaptophysin in comparison with the glial fibrillary acidic protein (GFAP) and S-100 protein in the PC12 cell line. In three different experiments, PC12 cells were maintained in a three-dimensional gelatin foam (Gelfoam) matrix system for up to 34 days with and without treatment with 1 mM dibutyryl cyclic (dc)AMP. Immunohistochemistry was performed on explants ranging from 2 to 32 days-in vitro, which were fixed in either Bouin's solution, 70% ethanol, or 10% neutral-buffered formalin and embedded in paraffin. Immunoblotting was performed on Gelfoam explants with a panel of antibodies against all aforementioned neuronal and glial markers. Additional immunoblot experiments using anti-GFAP and anti-beta III monoclonal antibodies in cell suspensions and homogenates from PC12 monolayer cultures were carried out to compare growth conditions in relation to the expression of these proteins.

RESULTS

Beta III and MAP2 were demonstrated by immunohistochemistry and immunoblotting of PC12 explants maintained for up to 32 days in Gelfoam matrices with and without treatment with dcAMP. Intense filamentous and granular beta III staining of PC12 cells was observed in dcAMP-treated cultures concomitant with neuronal morphologic alterations (neuritogenesis and ganglionic phenotype). In untreated cultures, beta III staining was present in less differentiated cells, as well in cells undergoing neuritic development. The neuronal phenotype of PC12 cells was confirmed by staining for MAP2, tau, and NF proteins, as well as for synaptophysin. The presence of beta III, MAP2, MAP1B, tau, and NF proteins was confirmed by immunoblotting. Clusters of GFAP-positive and S-100 protein-positive spindle cells, phenotypically distinct from the chromaffin-like or neuronal cells, were demonstrated in Gelfoam explants at 5-30 days in vitro. In 30-day-old cultures treated with dcAMP, there was strong filamentous GFAP and diffuse S-100 protein staining in an increased number of sustentacular-like PC12 cells. GFAP staining was corroborated by immunoblotting of explants maintained under identical conditions in vitro. In contrast, immunoblots performed on homogenates from PC12 suspension and monolayer cultures were GFAP-negative.

CONCLUSIONS

Neuronal and glial-like, presumed sustentacular, phenotypes were demonstrated in PC12 cells grown in Gelfoam matrices with and without treatment with dcAMP for up to 34 days. To our knowledge, the occurrence of glial differentiation in the PC12 line is a hitherto unreported finding. Adult rat medullary sustentacular cells are known to express S-100 and GFA proteins (Suzuki and Kachi, Kaibogaku Zasshi-Anat 70(2): 130-139, 1995), and the organ culture system employed in our study may well have favored this direction of differentiation.

Class III beta-tubulin isotype (beta III) in the adrenal medulla: II. Localization in primary human pheochromocytomas

BACKGROUND

The Class III beta-tubulin isotype (beta III) is expressed specifically in central and peripheral nervous system neurons at various stages of neuronal differentiation. We have shown previously that beta III is expressed in a differentiation-dependent manner in human neuroblastomas arising in the adrenal medulla and sympathetic chains (Katsetos et al., Clin Neuropathol 13:241-255, 1994). The neuronal distribution of beta III in the developing and mature human adrenal medullae is detailed in the companion article (Katsetos et al., 1998A).

METHODS

We have compared the localization of the neuronal beta III to S-100 protein, a sustentacular cell marker, in 14 formalin-fixed, paraffin-embedded primary human pheochromocytomas of the adrenal medulla and 14 adrenocortical tumors (adenomas and carcinomas).

RESULTS

In pheochromocytomas, beta III staining was present in all tumors, but the number of stained cells varied in the two neural neoplastic phenotypes. Although the majority of chromaffin-like cells were beta III-positive, there was a lack of beta III in one-third of the tumor cells. Compared to chromaffin-like phenotypes, neuronal (ganglion-like cells) were invariably beta III-positive. Stromal sustentacular cells, stromal fibroblasts, and tumor blood vessels were beta III-negative. Sustentacular cells in pheochromocytomas were S-100 protein-positive, but beta III-negative. Primary adrenocortical tumors were beta III-negative with the exception of rare beta III-positive cells demonstrated in one case.

CONCLUSIONS

The distribution of beta III in human pheochromocytomas of the adrenal gland is differentiation-dependent, closely recapitulating chromaffin cell and neuronal phenotypes of the normal adrenal medulla. Our findings indicate that beta III may be used as one of the adjuvant neural markers in the differential diagnosis of adrenal tumors, i.e., pheochromocytoma versus adrenocortical carcinoma. The occurrence of rare beta III-positive cells in cortical carcinomas is exceptional and probably represents the acquisition of a divergent neuroendocrine phenotype. The significance of the latter is unclear, although it may constitute a marker for malignancy.

Subependymal astrocytic hamartomas in the Eker rat model of tuberous sclerosis

Tuberous sclerosis (TSC) is an autosomal dominant syndrome that is linked to two genetic loci: TSC1 (9q34) and TSC2 (16p13). Brain manifestations such as cortical tubers and subependymal hamartoma/giant cell astrocytomas are major causes of TSC-related morbidity. In this study, we describe the central nervous system involvement in a unique rodent model of tuberous sclerosis. The Eker rat carries a spontaneous germline mutation of the TSC2 gene and is predisposed to multiple neoplasia. In a series of 45 adult Eker carriers (TSC2 +/-), three types of focal intracranial lesions were found, of which the subependymal and subcortical hamartomas were most prevalent (65%). There exist remarkable phenotypic similarities between the Eker rat and human subependymal lesions. Our study indicates that the predominant cellular phenotype of the subependymal hamartomas is astroglial and suggests that the neuronal contribution within these lesions is, in part, the result of pre-existing myelinated axons. The hamartomas did not show evidence of loss of the wild-type TSC2 allele; it remains to be determined whether TSC2 inactivation is necessary for their pathogenesis. This genetically-defined rodent model may be useful in elucidating the molecular and developmental basis of the subependymal giant cell astrocytoma in humans.

Neurofibrillary lesions in experimental aluminum-induced encephalopathy and Alzheimer's disease share immunoreactivity for amyloid precursor protein, A beta, alpha 1-antichymotrypsin and ubiquitin-protein conjugates

Neurofibrillary tangles of Alzheimer's disease contain predominantly tau protein and to a lesser degree amyloid precursor protein (APP), A beta protein, alpha 1-antichymotrypsin (ACT) and ubiquitin. Previously we have demonstrated the presence of phosphorylated tau and neurofilament proteins in neurofibrillary degeneration (NFD) induced by aluminum (Al) maltolate in rabbits [Savory et al., Brain Res. 669 (1995) 325-329; Savory et al., Brain Res. 707 (1996) 272-281]. Using the same animal system we have now detected APP, A beta, ACT and ubiquitin-like immunoreactivities in NFD-bearing neurons, often colocalizing in the NFD. Diffuse cytoplasmic staining for APP, A beta and ubiquitin was also present in neurons without NFD from Al maltolate-treated rabbits. This study provides additional support for immunochemical similarities between Al-induced NFD in rabbits and the neurofibrillary tangles in human subjects with Alzheimer's disease.

Inducible nitric oxide synthase in Theiler's murine encephalomyelitis virus infection

We investigated the role of inducible nitric oxide synthase (iNOS) in Theiler's murine encephalomyelitis virus (TMEV) infection of susceptible (SJL) and resistant (C57BL/6 [B6]) strains of mice. TMEV is an excellent model of virus-induced demyelinating disease, such as multiple sclerosis (MS). Previous studies of others have suggested that NO may play a role in the pathogenesis of demyelinating disease. The presence and level of iNOS were determined in the brains and spinal cords of SJL and B6 TMEV-infected mice by the following methods: (i) PCR amplification of iNOS transcripts, followed by Southern blotting with an iNOS-specific probe, and (ii) immunohistochemical staining with an anti-iNOS-specific affinity-purified rabbit antibody. iNOS-specific transcripts were determined in the brains and spinal cord of both SJL and B6 TMEV-infected mice on days 0 (control), days 3, 6, and 10 (encephalitic stage of disease), and days 39 to 42, 66, and 180 (demyelinating phase) postinfection (p.i.). iNOS-specific transcripts were found in the brains and spinal cords of both SJL and B6 TMEV-infected mice at 6, 10, and 39 (SJL) days p.i., but they were absent in mock-infected mice and in TMEV-infected SJL and B6 mice at 0, 3, 66, and 180 days p.i. Immunohistochemical staining confirmed the presence of iNOS protein in both TMEV-infected SJL and B6 mice at days 6 and 10 p.i., but not at days 0, 3, 66, and 180 days p.i. Weak iNOS staining was also observed in TMEV-infected SJL mice at 42 days p.i. iNOS-positive staining was found in reactive astrocytes surrounding areas of necrotizing inflammation, particularly in the midbrain. Weak iNOS staining was also observed in cells of the monocyte/macrophage lineage in areas of parenchymal inflammation and necrosis (mesencephalon) and in leptomeningeal and white matter perivascular infiltrates of the spinal cord. Rod-shaped microglia-like cells and foamy macrophages (myelin-laden) were iNOS negative. These results suggest that NO does not play a direct role in the late phase of demyelinating disease in TMEV-infected mice.

Cerebral uric acid increases following experimental traumatic brain injury in rat

Following traumatic brain injury (TBI), cortical and thalamic areas were analyzed histologically and by high-performance liquid chromatography with electrochemical detection for uric acid at various survival times. Following TBI, cortical uric acid was elevated by ten-fold at 24 and 48 h, but not at 1 h post-TBI. Histological evidence of neurodegeneration was found not only in cortex but also in the anteroventral thalamus. These data suggest that as in stroke, uric acid measurements may be a convenient and sensitive method for measuring peroxidative status in TBI.

Post-anesthesia uncal herniation secondary to a previously unsuspected temporal glioma

We report the case of a 21-year-old male who sustained an uncal herniation and subsequent brain death following general anesthesia, for a minor orthopedic procedure, owing to the presence of a large, unsuspected temporal glioma. The possible factors responsible for the precipitation of this event are appraised.

Calbindin-D28k in subsets of medulloblastomas and in the human medulloblastoma cell line D283 Med

OBJECTIVE

To evaluate the antigenic expression of calbindin-D28k in surgically resected cerebellar medulloblastomas and the human medulloblastoma cell line D283 Med in relation to glial neoplasms, the human glioblastoma (U-251 MG) and rat glioma (C-6) cell lines, and other primary and metastatic brain tumors.

DESIGN

Immunohistochemical staining was performed using an antiserum and a monoclonal antibody against calbindin-D28k on (1) formalin-fixed, paraffin-embedded human, predominantly posterior fossa, brain tumor specimens (49 medulloblastomas, 59 glial and mesenchymal primary central nervous system tumors, 1 posterior fossa rhabdoid tumor, and 34 metastatic tumors); (2) formalin-70% alcohol-, or Bouin's-fixed tumor cell lines (D283 Med, U-251 MG, and C-6) maintained in a three-dimensional gelatin foam (Gelfoam matrix) system, with or without treatment with dibutyryl cyclic adenosine monophosphate; and (3) formalin-fixed, paraffin-embedded C-6 glioma cells transplanted intracerebrally to rats.

RESULTS

Calbindin-D28k immunohistochemical staining was detected in 20 of 49 cerebellar medulloblastomas and in cells of the human medulloblastoma cell line D283 Med grown in gelatin Gelfoam matrices, with or without treatment with dibutyryl cyclic adenosine monophosphate. In surgical resection specimens, calbindin-D28k reactivity was evident in populations of poorly differentiated cells of classic (non-nodular) medulloblastomas (16/20) and in mature Purkinje neuronlike phenotypes in medulloblastomas with ganglion cells (4/6) but was absent in desmoplastic medulloblastomas, including in areas of neoplastic neuritogenesis ("pale islands") (0/23). Calbindin-D28k staining was also present in D283 Med explants for up to 29 days in vitro. Reactivity was more widespread in dibutyryl cyclic adenosine monophosphate-treated cultures, coinciding with neuronal morphologic alterations of cultured cells. Focal calbindin-D28k stainig was present in neural-like cells of an embryonal cerebellar tumor with divergent mesenchymal, epithelial, and neuroectodermal/neuroendocrine differentiation suggestive of a malignant rhabdoid tumor. No calbindin-D28k staining was obtained in primary glial and mesenchymal (intra- and extra-axial) brain tumors (0/59), in explants of human glioblastoma cell line U-251 MG, or in the rat glioma line C-6 maintained in Gelfoam matrices or transplanted intracerebrally. Among 34 epithelial and mesenchymal tumors metastatic to the posterior fossa, only subpopulations of cells in two small-cell (neuroendocrine) carcinomas originating in the lung were calbindin positive.

CONCLUSION

Calbindin-D28k expression in classic medulloblastomas, medulloblastomas with ganglion cells, and in the human medulloblastoma cell line D283 Med (which was derived from a metastatic classic medulloblastoma) suggests a phenotypic kinship between subsets of this tumor and neuronal progeny of the ventricular neuroepithelium, thus conferring additional support for its neuroblastic nature.

A cytomorphological scheme of differentiating neuronal phenotypes in cerebellar medulloblastomas based on immunolocalization of class III beta-tubulin isotype (beta III) and proliferating cell nuclear antigen (PCNA)/cyclin

This immunohistochemical study compares the localization of the neuronal class III beta-tubulin isotype (beta III) to that of the proliferating cell nuclear antigen (PCNA)/cyclin in 46 cerebellar neuroblastic tumors (medulloblastomas). Both class III beta-tubulin (beta III) and PCNA/cyclin reactivities were present in all tumors, but the topographic distribution and cytomorphologic features of stained cells varied considerably between classic and desmoplastic medulloblastomas. Four neoplastic phenotypes, representing gradations of neuronal differentiation, were identified: [Allegranza 1991] apolar, blast-like PCNA/cyclin(+) cells devoid of beta III reactivity (Nb1); [Bravo et al. 1987] apolar, often binucleated and/or fusiform, PCNA/cyclin (+) cells with pronounced beta III staining in their protoperikarya and their growth cones (Nb2); [Burger et al. 1987] beta III-immunoreactive immature polar neurons with varying degrees of neuritic development, reading to significant neuritogenesis in the "pale islands" of desmoplastic medulloblastomas (Nb3). The majority of Nb3 phenotypes were PCNA/cyclin (-), although subpopulations of such polar tumor cells exhibiting PCNA staining were also identified; and [Burger et al. 1991] beta III-immunoreactive, PCNA/cyclin (-) mature ganglion-like cells (Nb4). A high PCNA/cyclin labeling index (> 80%) was obtained in 20 poorly differentiated classic medulloblastomas while, significant intratumoral staining heterogeneity was observed in 23 cases of desmoplastic medulloblastomas and 3 cases of "medulloblastomas with ganglion cells": A high labeling index (LI)(> 80%) in the reticulin-impregnated poorly differentiated areas of tumor contrasted with sharp decline of PCNA staining and a very low LI (< 10%) in areas of overt neoplastic neuritogenesis ("pale islands") displaying strong beta III reactivity. Neoplastic ganglion cells were beta III (+)/PCNA (-). Our findings indicate that the majority of differentiating neuronal phenotypes undergoing cytomorphological changes of neuritic development (Nb3), and all neoplastic ganglion cells (Nb4 phenotypes) are PCNA (-), in contrast to actively proliferating, poorly differentiated, tumor cells that are PCNA (+). Although PCNA staining corresponded in part, to beta III (-) blast-like elements (Nb1), a co-expressive pattern of staining for beta III and PCNA/cyclin also was observed in subpopulations of poorly differentiated tumor cells (Nb2), indicating that transformed neuroblasts are capable of expressing differentiation-associated neuronal cytoskeletal proteins while still remaining in the proliferative compartment of the cell cycle. Our observations suggest that only neuritogenesis and acquisition of ganglionic phenotype are significant maturational events in medulloblastomas (indicating entry into the quiescent phase of the cell cycle) and provide further support for the neuronal lineage and differentiation potential of these cerebellar embryonal tumors.

Renal cell carcinomatous meningitis: pathologic and immunohistochemical features

We report the clinical, radiographic, pathologic, and immunohistochemical features of a patient with widespread meningeal carcinomatosis from renal cell carcinoma. Clear and spindle tumor cell subtypes infiltrated the meninges of the cauda equina, oculomotor nerve, spinal cord, and cerebral hemispheres, forming abortive glandular or tubular aggregates without evidence of parenchymal invasion. Cytokeratin epitopes were labeled immunohistochemically with Cam 5.2 antibodies, but epithelial membrane antigen and neuron-specific enolase were not present.

Thallium imaging for brain tumors with results measured by a semiquantitative index and correlated with histopathology

BACKGROUND

The optimal management of patients with brain tumors requires knowledge of the tumor characteristics upon presentation and the discovery of recurrence after therapy. Thallium-201 (Tl-201) chloride has shown varying uptake in tumors, depending on their viability and the type and degree of malignancy. This study explores the diagnostic potential of thallium imaging in patients with brain tumors.

METHODS

Forty-three Tl-201 single photon emission computed tomographic scintigrams were performed on 40 patients with intracranial neoplasms, nearly equally divided between patients with no prior treatment and patients who had prior treatment and were suspected to have recurrent tumor and/or radiation necrosis. A thallium tumor index was calculated as the ratio of counts for a region of interest drawn in the lesion area and its mirror image in normal brain tissue. A two-tailed Student's t test was performed to compare the thallium index and histopathologic findings.

RESULTS

A value of 1.5 for the thallium tumor index allowed for the best correlation between the prediction of malignancy and the histopathologic results. In the pretreatment group, a thallium tumor index greater than 1.5 correlated with high grade malignancy, and less than 1.5 correlated with either a well differentiated astrocytoma or benign cyst. In the posttreatment group, a thallium tumor index greater than 1.5 correlated with recurrent and/or residual malignant tumor.

CONCLUSIONS

For those patients undergoing initial evaluation, the thallium study can help in the differential diagnosis of an intracranial mass lesion and offers confirmation of results of biopsy. For those patients who already have received treatment, the study can be used to detect recurrent or residual tumor.

Lobar pilocytic astrocytomas of the cerebral hemispheres: I. Diagnosis and nosology

This study provides neuropathological and neuroradiological observations on 11 cases of lobar pilocytic astrocytomas of the cerebral hemispheres, reappraising potential diagnostic caveats. These tumors may show variable degrees of contrast enhancement on computed tomography, as well as gadolinium uptake on magnetic resonance imaging, making them indistinguishable from malignant gliomas. Histopathologically, although typically pilocytic, they may exhibit areas of increased cellular density with protoplasmic and multinucleated glial elements (pilo-protoplasmic astrocytoma). The presence and particularly the abundance of distinct gliodegenerative structures, i.e. eosinophilic granular bodies (EGBs) and to a lesser degree Rosenthal fibers, in conjunction with collateral clinical, histologic and imaging parameters may facilitate oncotypic diagnosis. Mixed pilocytic and fibrillary astrocytomas are recognized, while malignant change may also rarely occur in longstanding lobar pilocytic astrocytomas.

Lobar pilocytic astrocytomas of the cerebral hemispheres: II. Pathobiology--morphogenesis of the eosinophilic granular bodies

This study provides new immunocytochemical observations on the so-called eosinophilic granular bodies (EGBs), seen predominantly (but not exclusively) in pilocytic astrocytomas. Using combined immunohistochemical and immunoelectron microscopic approaches on formalin-fixed, paraffin-embedded tissues, we have demonstrated that (1) EGBs exhibit pronounced reactivity with antibodies to serine protease inhibitors alpha-1-antichymotrypsin and alpha-1-antitrypsin; by immunoelectron microscopy, the reaction product is localized either in the form of diffuse floccular densities, or larger conglomerates of amorphous, globular material; (2) an antiserum to ubiquitin-protein conjugates, codistributes in the EGBs at the light microscopic level, while ultrastructurally is either localized in diffuse, finely granular deposits, and/or fragmented filamentous particles; and (3) that a monoclonal antibody to beta-amyloid precursor protein (beta-APP) stains smaller EGBs. The detection of serpin-like and beta-APP-like staining in EGBs may be a reflection of acute phase reactant activity in response to tumor-produced proteases. We postulate that EGBs contain complexes of serpins and hitherto unknown protease(s), which are in turn probably degraded via ubiquitin mediated mechanism(s). Although EGBs typify pilocytic astrocytomas, they may be exceptionally present in malignant astrocytomas, calling for cautious interpretation of their biologic as well as prognostic import.

Localization of the neuronal class III beta-tubulin isotype in foci of early neuritogenesis supports divergent neuroblastic differentiation potential in Wilms' tumors

Wilms' tumors are embryonic neoplasms that have been proposed to originate from the metanephric blastema and are capable of divergent epithelial and mesenchymal differentiation. Neuroepithelial differentiation in these tumors remains controversial. The aim of this study was to examine the phenotypic profile of certain neuronal and glial antigenic determinants in a series of 21 Wilms' tumors. Immunohistochemical studies were performed by using monoclonal antibodies against the neuronal class III beta-tubulin isotype (beta III), the phosphorylated and phosphorylation-independent epitopes of neurofilament protein, and synaptophysin; antisera to gamma-enolase (neuron-specific enolase) glial fibrillary acidic protein, and S100 protein were also used. Foci of neoplastic cells with neurite-like processes that exhibited intense beta III staining were demonstrated in blastemalike areas of three of 21 tumors. In one case, Homer Wright rosettes (stained for beta III) were identified. Areas of abortive neuritic development were also labeled with antibodies to gamma-enolase. No reactivity was obtained in these foci for phosphorylated and phosphorylation-independent epitopes of neurofilament protein, synaptophysin, glial fibrillary acidic protein, and S100 protein. The remainder of the tumors (18 of 21) were negative with the panel of neural markers. Our results indicate that divergent neuroblastic differentiation, evidenced as early neoplastic neuritogenesis, may be present in the blastematous component of Wilms' tumor subsets.

Neuron-associated class III beta-tubulin, tau, and MAP2 in the D-283 Med cell line and in primary explants of human medulloblastoma

The D283 Med human medulloblastoma cell line and primary explants of five surgically excised medulloblastomas were cultured using a three-dimensional Gelfoam matrix system. The cultures were evaluated immunohistochemically for a series of antigenic determinants associated with neuronal or glial differentiation. Focal immunolocalization of class III beta-tubulin, microtubule-associated protein 2 (MAP2), and to a lesser degree tau, was demonstrated in all cultures. Class III beta-tubulin isotype, MAP2, and tau protein were also detected by immunoblot in Gelfoam matrix cultures, monolayer cultures, and suspension cultures of D283 Med cells. Staining for neurofilament protein epitopes was highly variable, even among different cultures derived from the same original tumour, but time-dependent changes in neurofilament protein, which may have reflected neuronal differentiation, were not consistently shown. Widespread gamma-enolase and focal synaptophysin reactivities were visualized in all cultures, but no S-antigen staining was detected. Leu 7 labelling was variably present in half of the cultures of D283 Med cells, but was more abundant in explants derived from four of the five original tumours. Vimentin was consistently found in D283 Med cultures at all time points. No immunoreactivity for glial fibrillary acidic protein was detected in the D283 Med cell line. Conversely, staining for this protein was demonstrated in scattered astrocytic cells in the surgical specimens of all five medulloblastomas. Concomitant with increased time in culture, three of the primary tumours displayed increased numbers of glial fibrillary acidic protein-positive cells when cultured in the Gelfoam system, but the other two tumours had a minimal astrocytic component.(ABSTRACT TRUNCATED AT 250 WORDS)

The stromal Schwann cell during maturation of peripheral neuroblastomas. Immunohistochemical observations with antibodies to the neuronal class III beta-tubulin isotype (beta III) and S-100 protein

This immunohistochemical study compares the localization of the neuronal class III beta-tubulin isotype (beta III; analogous to the beta' 1-/beta 2-tubulin isoform) to the Schwann cell-associated S-100 protein focusing on topographic relationships of Schwann-like cells to differentiating neuronal phenotypes during stromal development in human peripheral neuroblastomas. The earliest appearance of Schwann cells in poorly differentiated (classical) neuroblastomas is heralded by S-100 protein-immunoreactive cells in close association with tumor blood vessels. In subsequent stages of maturation, i.e. maturing neuroblastoma (ganglioneuroblastoma and gangliocytoma), S-100 protein-positive cells are mostly confined to the connective tissue septa dividing tumor into lobules, and are not freely interspersed with beta III-immunoreactive neoplastic neurons. Significant ensheathment of individual axon-like processes by Schwann cells occurs only in mature ganglioneuromas. beta III is localized in a full spectrum of neoplastic neuronal phenotypes, ranging from poorly-differentiated apolar neuroblasts (often signaling ensuing neuritogenesis) to mature ganglion cells, but not in Schwann cells, or other cell types of the stroma. Our observations suggest that Schwann cells in peripheral neuroblastomas are stroma-derived cells and not an expression of divergent neoplastic differentiation.

Novel immunohistochemical localization of 28,000 molecular-weight (Mr) calcium binding protein (calbindin-D28k) in enterochromaffin cells of the human appendix and neuroendocrine tumors (carcinoids and small-cell carcinomas) of the midgut and foregut

Calbindin-D28k is a highly conserved 28,000 (dalton) molecular-weight (Mr) calcium binding protein with broad tissue distribution, yet cell-type-specific expression predominantly in subpopulations of central and peripheral nervous system neurons, distal tubular cells of the kidney, and enteric neuroendocrine cells. A polyclonal antiserum against rat renal calbindin-D28k and a monoclonal antibody to calbindin-D28k purified from chicken intestine (clone CL-300) were used for immunohistochemical evaluation of formalin-fixed, paraffin-embedded tissues from multiple areas of the human small and large intestines and 93 primary neoplasms of the gastrointestinal tract (foregut, midgut, and hindgut derivatives) and the lung (foregut derivative). Calbindin-D28k immunostaining was obtained in a minority of enterochromaffin (neuroendocrine) cells, predominantly of the appendix and small intestine, as well as in autonomic neurons of the neural plexuses. Focal cytoplasmic Golgi-type staining was obtained with monoclonal antibody CL-300 in the appendiceal surface epithelium and dendritic macrophages confined to the appendiceal lymphoid follicles. Epithelial progenitor cells in enteric crypts and absorptive, goblet, and Paneth cells were calbindin-D28k negative, while no immunoreactivity was demonstrated in the mucosae of the colon and rectum. Calbindin-D28k staining was consistently detected in subpopulations of neuroendocrine phenotypes in midgut (appendiceal/ileal) and foregut (bronchial) carcinoids and small-cell carcinomas, but was absent in adenocarcinomas, squamous cell carcinomas, leiomyomas/leiomyosarcomas, schwannomas, and lymphomas. Our observations suggest that calbindin-D28k is a novel adjuvant neuroendocrine marker that is potentially useful in diagnostic tumor immunohistochemistry.

Medulloblastoma

The histogenetic approach to the classification of embryonal tumors of the central nervous system has historically received wide acceptance as a scheme for histologic typing and nosologic definition. Medulloblastoma is a paradigm of a neuroblastic neoplasm whose origins and differentiation potential are traceable to cerebellar embryogenesis. Medulloblastomas show unequivocal neuroblastic maturational changes evidenced by neuritogenesis and expression of neuronal cytoskeletal and other neuronal differentiation-associated antigenic determinants. In addition, ganglion cells form in some lesions. Based on differential patterns of immunoreactivity for calbindin-D28k (a ventricular matrix (VM)-associated neuronal calcium binding protein, which is not expressed in the external granule layer (EGL) or its progeny) and the class III beta-tubulin isotype (beta III) (expressed metachronously in the neuronal descendants of both neuroepithelia), it is possible that distinct subsets of medulloblastomas may implicate clonally-related neuroblasts from two sources: VM for classic medulloblastomas and the EGL for desmoplastic (nodular) medulloblastomas. However, the possibility of two separate origins for the classic medulloblastomas cannot be entirely excluded. Origin from the VM is suggested for the rare subset of medulloblastomas with ganglion cells. It is, however, unclear whether these ganglion cells are neoplastic (products of terminal neuronal differentiation), or dysplastic (entrapped preexisting elements of cerebellar heterotopias). Glial differentiation (gliomatous transformation) in medulloblastomas is at issue but is documented in rare cases of classic medulloblastomas (presumed heteroclones of cotransformed VM glial precursors), or desmoplastic medulloblastomas (probable stromal glial transformation-induction). Astrocytic proliferations in desmoplastic medulloblastomas may be stroma-derived (neuronal differentiation-associated), analogous to Schwann cell contributions during maturation of peripheral neuroblastomas.

Differential localization of class III, beta-tubulin isotype and calbindin-D28k defines distinct neuronal types in the developing human cerebellar cortex

This immunohistochemical study compares the localization of the neuronal class III beta-tubulin isotype (beta III) to that of calbindin-D28k in 40 human fetal and postnatal cerebella ranging from 12 weeks gestation to adulthood. In the external granule layer of the developing cerebellar cortex, beta III staining was present in the premigratory (postmitotic) zone of horizontal neurons but was absent in "epithelioid" cells of the subpial proliferative mitotic zone. In the molecular layer, intense beta III staining was associated with parallel fibers, stellate/basket neurons and migrating fusiform granule neurons. beta III staining was also present in internal granule neurons. In contrast, beta III was not detectable in fetal and neonatal Purkinje neurons and Golgi II neurons, but was evident in these neurons from juvenile and adult cerebella. Calbindin-D28k staining was present in Purkinje neurons also delineating their somatic spines ("pseudopodia"), lateralizing and apical dendrites (including dendritic spines), subpopulations of small to intermediate-sized Golgi II neurons in the internal granule layer ("synarmotic cells" of Landau), large to medium-sized subcortical Golgi II neurons and neurons of cerebellar roof nuclei, at various gestational stages and postnatally. It was absent in the external granule layer, parallel fibers, stellate/basket and internal granule neurons. Variable degrees of beta III and calbindin-D28k staining were detected in subpopulations of immature neuroepithelial cells of the ventricular matrix at the roof of the fourth ventricle. Glial (including Bergmann glia) and mesenchymal cells were not stained for either antigenic determinants. The differential expression of calbindin-D28k and beta III defines distinct populations of neurons in the developing human cerebellar cortex and supports the ontogenetic concept of Ramon y Cajal.

Absence of neuron-associated microtubule proteins in the rat C-6 glioma cell line. A comparative immunoblot and immunohistochemical study

Three neuron-associated microtubule proteins, Class III beta-tubulin isotype, MAP-2, and tau, were evaluated in a comparative immunoblot and immunohistochemical study of the rat C-6 glioma cell line maintained for up to 31 days in vitro. Western blots on whole SDS extracts of cells grown: (i) as monolayers on plastic dishes (for 13 and 16 days); (ii) as monolayers on poly-D-lysine coated glass coverslips (for 3, 7, and 11 days); and (iii) as explants on Gelfoam matrices (for 10, 30, and 31 days) were probed with monoclonal antibodies (MoAb) specific for the above-mentioned microtubule proteins. For these and all other markers employed, immunoperoxidase histochemistry was performed only on the matrix cultures. The immunoblot experiments demonstrated that the Class III beta-tubulin isotype, MAP2, and tau were not expressed by the C-6 cell line in any of the culture conditions, nor were they found by immunohistochemistry. In contrast, explants from all culture conditions were positive for glial fibrillary acidic (GFA) protein and for a universal anti-beta-tubulin isotype MoAb by immunoblotting, as well as by immunohistochemistry in Gelfoam matrix cultures maintained in an organ culture system. Both sets of experiments indicate that these markers are not altered under three different conditions of growth over a one-month period in vitro. The expression of GFA protein and the absence of detectable levels of Class III beta-tubulin, MAP2, and tau are in keeping with the astrocytic phenotype of the C-6 cell line.

Abnormal intracerebral thallium localization in a bacterial brain abscess

A 56-yr-old man with a prior history of renal cell carcinoma had moderately intense abnormal localization of 201Tl-chloride in a solitary brain lesion which was discovered to be a bacterial abscess. The organisms isolated by culture included Actinomycosis odontolyticus, Peptostreptococcus and Hemophilus aphrophilus. Because of the clinical presentation, MRI characteristics and thallium scintigraphic findings, the lesion had been felt to represent either a primary or a metastatic neoplasm. This case illustrates the need for caution in the interpretation of thallium brain scintigram.

Neuron-associated class III beta-tubulin isotype, microtubule-associated protein 2, and synaptophysin in human retinoblastomas in situ. Further immunohistochemical observations on the Flexner-Wintersteiner rosettes

We studied by immunohistochemistry 26 retinoblastomas in situ using monoclonal antibodies specific for the neuron-associated class III beta-tubulin isotype (h beta 4), microtubule-associated protein 2 (MAP2), and synaptophysin. Anti-h beta 4 and anti-MAP2 immunostaining was consistently obtained in the Flexner-Wintersteiner rosettes, in fleurettes, in Homer Wright (neuroblastic) rosettes, and also variably among poorly differentiated tumor cells. A similar pattern of antisynaptophysin immunopositivity was seen, but was especially pronounced in the adluminal borders of cells forming the Flexner-Wintersteiner rosettes. The demonstration of h beta 4, MAP2, and synaptophysin epitopes in poorly differentiated and maturing neoplastic phenotypes in retinoblastomas attests to the neuronal character of this embryonal tumor. Immunoreactivity toward h beta 4 and MAP2 epitopes by poorly differentiated neoplastic cells may indicate early neuronal commitment in retinoblastoma. The consistent immunostaining of Flexner-Wintersteiner rosettes with monoclonal antibodies to h beta 4 and MAP2 is in keeping with the previous ultrastructural documentation of microtubules with a neuronal-like spatial organization present in the cells of these structures.

Neuronal cytoskeletal lesions induced in the CNS by intraventricular and intravenous aluminium maltol in rabbits

The antigenicity of neuronal cytoskeletal lesions was studied immunohistochemically in adult New Zealand white rabbits after intraventricular (subacute) and intravenous (chronic) administration of a water-soluble aluminium compound, aluminium (Al) maltol. After short-term intraventricular administration, rabbits developed widespread neurofibrillary degeneration (NFD) involving pyramidal neurons of the isocortex and allocortex, projection neurons of the diencephalon, and nerve cells of the brain stem and spinal cord. There was a predilection for motor neuron involvement and for the infratentorial portions of the neuraxis. Perikarya and proximal neurites were especially affected. Bundles of 10 nm filaments were frequently present. Three of the animals treated intravenously for 12 weeks or longer displayed NFD in the oculomotor complex and in the pyramidal neurons of the occipital isocortex. Following either mode of administration, the affected neurons exhibited immunostaining with a panel of monoclonal antibodies (MAbs) against phosphorylated (SMI-31), non-phosphorylated/phosphatase-sensitive (SMI-32), and dephosphorylation-independent (SMI-33) epitopes of high and middle molecular weight neurofilament (NF) protein subunits. They were non-reactive with MAbs to microtubule-associated protein 2 and the class III neuron-associated beta-tubulin isotype. Our findings indicate that intraventricular Al maltol produces similar, but more widespread degeneration of projection-type neurons than the less water-soluble Al compounds as reported by others. The NFD lesions are compared with those of senile dementia of the Alzheimer type (SDAT) and motor neuron disease.

Antigenic expression of neuron-associated class III beta-tubulin isotype (h beta 4) and microtubule-associated protein 2 (MAP2) by the human retinoblastoma cell line WERI-Rb1. A comparative immunoblot and immunocytochemical study

The antigenic expression of two neuron-associated microtubule proteins, class III beta-tubulin isotype (h beta 4) and microtubule-associated protein 2 (MAP2), was evaluated in a comparative immunoblot and immunocytochemical study of the human retinoblastoma cell line WERI-Rb1 maintained for up to 30 days in three different in vitro conditions. Western blots were performed on whole sodium dodecyl sulfate extracts of cells grown in floating suspensions, on Gelfoam matrices and on coverslips. Immunoperoxidase histochemistry was performed on matrix cultures. Immunoblotting demonstrated that h beta 4 and MAP2 were present under all culture conditions. By immunocytochemistry, staining of cytologically undifferentiated cells with anti-h beta 4 and anti-MAP2 monoclonal antibodies was found on Gelfoam matrix explants. In contrast, glial fibrillary acidic protein was not detected by either immunoblots or immunocytochemistry. These findings are in keeping with the solely neuroblastic nature of this line and provide no evidence for its divergent (i.e. neuronal and glial) differentiation capacity.

An immunohistochemical study of neuropeptides and neuronal cytoskeletal proteins in the neuroepithelial component of a spontaneous murine ovarian teratoma. Primitive neuroepithelium displays immunoreactivity for neuropeptides and neuron-associated beta-tubulin isotype

Approximately one third of the female mice of the LTXBO strain develop spontaneous ovarian teratomas. These tumors contain a large neuroepithelial component, which includes primitive neural structures resembling embryonic neural tubes (medulloepithelial rosettes), ependymoblastic and ependymal rosettes, neuroblasts, mature ganglionic neurons, myelinated neurites, and astrocytes. The purpose of this study was to characterize these tumors according to the immunohistochemical location of some well-characterized trophic and regulatory neuropeptides and neurotransmitters, several neuronal-associated cytoskeletal proteins, and other proteins indicative of neuronal and glial differentiation. Medulloepithelial rosettes showed focal serotonin-like, opioid peptide-like and gamma-amino butyric acid-like immunoreactivity, and displayed immunostaining for the neuron-associated class III beta-tubulin isotype. The mature ganglion cells were also immunoreactive for these markers, and, in addition, for somatostatin, cholecystokinin, bombesin, glucagon, vasoactive intestinal peptide, and neuropeptide Y. Mature ganglion cells were also immunoreactive for proteins associated with the neuronal cytoskeleton (including microtubule-associated proteins, MAP2 and tau, and higher molecular weight phosphorylated and non-phosphorylated neurofilament subunits), neuron-specific enolase, and synaptophysin. Undifferentiated stem cells, ependymoblastic and ependymal rosettes, and astroglia all stained with a monoclonal antibody that recognizes all mammalian beta-tubulin isotypes, but did not react with antibodies to neuronal-associated cytoskeletal proteins or neuropeptides. Neuropeptide-like immunoreactivity and demonstration of the class III beta-tubulin isotype indicate early neuronal commitment in neoplastic primitive neuroepithelium. These patterns of immunoreactivity closely follow those encountered in the normal neurocytogenesis of the mammalian and avian forebrain, and increase the precision with which the early stages of progressive neuroepithelial differentiation can be analyzed in human embryonal tumors of the CNS.

Cerebellar desmoplastic medulloblastomas. A further immunohistochemical characterization of the reticulin-free pale islands

We studied by immunohistochemistry the features of differentiation in 24 desmoplastic and 16 classic medulloblastomas (median patient ages, 18 and 6.5 years, respectively) with the use of a panel of cytoskeletal and synaptosomal markers. A distinctive pattern of immunoreactivity with a series of monoclonal antibodies (Mabs) was documented in the polar tumor cells forming the reticulin-free pale islands of the desmoplastic variant, denoting overt neuritogenesis. These comprised the following: (1) Mab Tp-NFP1A3 recognizing an epitope in the high-molecular-weight (Mr) isoform of neurofilament protein; (2) Mab AP18 to the high-Mr microtubule-associated protein 2; (3) Mab TUJ1 recognizing the class III beta-tubulin isotype (human h beta 4); and (4) Mab SY38 to synaptophysin. Immunoblot analysis confirmed the expression of h beta 4 in three medulloblastomas, yielding strong single bands in two desmoplastic medulloblastomas and a considerably weaker band in one classic medulloblastoma. Glial fibrillary acidic protein-positive tumor cells frequently formed an integral component of the pale islands. Oligodendrogliallike areas in one classic and in three desmoplastic medulloblastomas were immunopositive for the Mabs to synaptophysin, microtubule-associated protein 2, and h beta 4, indicating a neuroblastic nature. We propose that the reticulin-free structures of desmoplastic medulloblastomas constitute neoplastic foci with features of predominantly neuronal and, to a lesser degree, astroglial differentiation.