Multicystic encephalopathy: review of eight cases with etiologic considerations.

Multicystic encephalomalacia (MCE) is a rare lesion that arises during the perinatal period. Although hypoxic-ischemic insults may be responsible for this lesion, recent evidence suggests that herpesviruses may represent another etiologic agent. To elucidate the pathogenesis of MCE, eight cases collected over a 34-year period were evaluated for destructive lesions in gray and white matter. Immunocytochemical methods, in situ hybridization and polymerase chain reaction (PCR) methodology were employed to search for herpes simplex viruses types 1 and 2 (HSV1 and HSV2), cytomegalovirus (CMV), varicella zoster virus (VZV), Epstein-Barr virus (EBV) and JC variant of papovavirus (JCV). Review of the clinical histories revealed that there had been a complicated labor and delivery in 6/7 cases. Neuropathological lesions consisted of extensive tissue destruction, neuronal loss and gliosis in hemispheric white matter, cerebral cortex, basal ganglia, thalamus, cerebellum and brainstem tegmentum. Only one case showed evidence of latent HSV infection by PCR. CMV, VZV, JCV and EBV were not detected. Arteriopathy was noted in one case. The widespread nature of the lesions and their association with perinatal ischemia suggest that severe hypoxia may be the more common etiology of MCE. Term infants appear especially susceptible to this type of cerebral damage.

Immunohistochemical detection of myelin basic protein is a sensitive marker of myelination in second trimester human fetal spinal cord.

The Luxol fast blue (LFB) technique is widely used for the assessment of myelination. Lectin histochemistry using peanut agglutinin (PNA) has also been employed for this purpose. Recently, immunohistochemical methods using antibodies to several myelin-related proteins have been adopted to study myelination in humans. However, the relative sensitivities of these different methods for the detection of early myelination in the human fetal central nervous system have not been determined. Vibratome sections of cervical spinal cord from 15 human abortuses ranging in age from 15 to 24 gestational weeks (GW) were probed with immunohistochemical methods using antibodies to myelin basic protein (MBP), 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase), and myelin-associated glycoprotein (MAG). In addition, LFB and PNA histochemistry was employed. The degree of myelination observed in immunohistochemically stained sections was compared to that found in corresponding LFB- and PNA-stained paraffin-embedded tissues. The intensity of myelination was graded by two observers on a scale of 0 (none), +1 (mild), +2 (moderate), and +3 (marked). At all ages examined, the MBP immunohistochemical method revealed more myelin than LFB or MAG staining. CNPase could not be reliably detected until after 18 GW. Peanut agglutinin stained myelin, but subpial astrocytes and the intervening neuropil were also stained. These results suggest that MBP is a more sensitive marker for early human fetal myelination than CNPase, MAG, PNA or LFB.

Early myelination in the human fetal lumbosacral spinal cord: characterization by light and electron microscopy.

Myelination in the human central nervous system is well documented after 20 weeks of gestation (WOG). However, earlier stages of this process have not been described in detail, although it is assumed that human myelinogenesis is similar to that observed in other animals. We used light and electron microscopy to study myelination in the human lumbosacral spinal cord during the second trimester of gestation. The kinetics of myelin-associated gene expression were analyzed by immunocytochemistry using antibodies to the myelin markers myelin basic protein (MBP) and 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNPase). These studies show that in 12-13 WOG specimens, occasional MBP-positive processes are found in developing white matter in areas distinct from the root entry zones. At this time, ultrastructural study revealed early investment of axons by glial processes and rare compacted myelin. CNPase staining was qualitatively and quantitatively less than that of MBP. The numbers of MBP- and CNPase-positive myelin sheaths increased with time, and by 24 WOG many were evident in all areas of the spinal cord except in the corticospinal tracts. Ultrastructural study of corresponding areas revealed many thin lamellae of compact myelin. This study provides initial normative data for early human myelination in the lumbosacral spinal cord and may serve as a baseline for future developmental and pathological studies.

Neuronal nitric oxide synthase expression in developing and adult human CNS.

Neuronal nitric oxide synthase (nNOS) is constitutively expressed by subpopulations of neurons in the CNS and is involved in neurotransmission, learning and memory, and neuronal injury. While the distribution of nNOS neurons has been characterized in the rodent CNS, the expression in human brain has not been well documented. We determined the expression of nNOS in second trimester human fetal and adult brain. In second trimester fetal brain, the nNOS neurons are concentrated in the developing cerebral cortex at the subplate zone and in layer VI, the striatum, and in certain brainstem nuclei. The nNOS neurons are sparsely distributed in the hippocampus, and virtually absent in the cerebellar cortex. The nNOS neurons in the subplate zone extend their processes radially, suggesting a developmental role, perhaps in guidance. The number and distribution of NADPH diaphorase-positive neurons corresponds to that of the nNOS neurons. While the distribution of nNOS neurons in the adult brain is similar to that found in fetal brain, the overall density is lower in the adult. The highest density of nNOS neurons is found in the striatum followed by the neocortex. A region-specific role for nNOS neurons in human brain and a potential developmental role for nNOS in the cerebral cortex are suggested by these data.

Temporal and spatial expression of major myelin proteins in the human fetal spinal cord during the second trimester.

Immunohistochemical identification of myelin basic protein (MBP) is a sensitive method for assessing myelination in the human fetal central nervous system (CNS). However, the temporospatial relationship of expression of two other major myelin proteins, proteolipid protein (PLP) and myelin-associated glycoprotein (MAG) to that of MBP during fetal development has not been assessed in human tissues. Vibratome sections of cervical, thoracic and lumbosacral levels from 37 normal spinal cords of < or = 10 to 24 gestational week (GW) fetuses were analyzed using immunohistochemical methods. Using light microscopy, MBP was the first oligodendrocyte marker detected, present by 10 GW at more rostral levels. PLP and MAG were detected rostrally between 12 to 14 GW. All myelin proteins were expressed in anterior to posterior and rostral to caudal gradients. By the late second trimester, expression of MBP, PLP and MAG was noted in all locations in the spinal white matter except for the corticospinal tract. Expression of MAG was particularly marked in the posterior root entry zone and propriospinal tracts. The results suggest that PLP and MAG are expressed later than MBP but follow similar spatial gradients.

Quantification of myelin basic protein in the human fetal spinal cord during the midtrimester of gestation.

The amount of myelin basic protein (MBP) was quantified in human fetal spinal cords from 12 to 24 gestational weeks (GW). MBP expression was determined by Northern blot, quantitative immunoblot, and immunocytochemistry. The development of compact myelin was analyzed by electron microscopy. Thirty-eight human fetal spinal cords were obtained after elective termination of intrauterine pregnancies from healthy women. Northern blot analysis showed a 15.8-fold increase in MBP mRNA between 12 and 18 GW. From 18 to 24 GW, MBP mRNA increased by 2.2-fold. The mRNA data paralleled immunoblot results that showed a 90.5-fold increase in MBP (0.147 ng/mg to 13.3 ng/mg tissue) between 12 and 18 GW and an approximately 11.5-fold increase between 18 and 24 GW (13.3 ng/mg to 154 ng/mg tissue). Immunocytochemical analysis also showed increased staining for MBP with advancing gestational age. At 12 GW, MBP immunoreactivity was observed in all three spinal cord funiculi. By 18 GW, MBP was expressed throughout the spinal cord white matter with the exception of the lateral corticospinal tracts and in the rostral levels of the fasciculus gracilis. With respect to myelin, at 12 GW, rare, noncompacted myelin lamellae were observed by electron microscopy. By 18 GW, discrete areas of compact myelin were observed in areas that showed MBP immunoreactivity, and at 24 GW, compact myelin was prominent throughout the white matter of the spinal cord. This study demonstrates a quantitative increase in MBP expression that is associated with myelin formation during the second trimester of human gestation. This information may provide normative data that can aid in the diagnosis of myelin disorders of the preterm, neonatal, and pediatric spinal cord.

A case of Down's syndrome with diffuse Lewy body disease and Alzheimer's disease.

Almost all Down's syndrome (DS) patients over the age of 35 to 40 years have histologic features of Alzheimer's disease (AD). However, the presence of extrapyramidal features in up to 36% of these patients has no satisfactory pathologic explanation. We report an older patient with DS, dementia, and parkinsonian signs who showed pathologic changes of Parkinson's disease and cortical Lewy bodies in addition to AD. These parkinsonian changes may be related to chromosome 21 abnormalities.

Distinct light microscopic changes in human immunodeficiency virus-associated nemaline myopathy.

The purpose of this study was to compare histologic characteristics of congenital nemaline myopathy (CNM), adult-onset nemaline myopathy (AONM), and human immunodeficiency virus-associated adult-onset nemaline myopathy (HAONM). There was no difference between the pathology of CNM and AONM; however, HAONM had distinctive pathologic features by light microscopy. The fibers in HAONM showed marked intrasarcoplasmic changes, including small vacuoles and granular degeneration.

Unusual patterns of Histoplasma capsulatum meningitis and progressive multifocal leukoencephalopathy in a patient with the acquired immunodeficiency virus.

Disseminated histoplasmosis (DH) and progressive multifocal leukoencephalopathy occur in acquired immunodeficiency syndrome (AIDS). At autopsy, DH patients with central nervous system involvement almost always show extensive involvement of the lungs and reticuloendothelial system in addition to the brain, and progressive multifocal leukoencephalopathy is manifest as multiple demyelinating lesions in several locations in the brain. We describe an AIDS patient with a long history of aggressively treated DH who died with DH in the brain only; fungus was not found elsewhere at autopsy. In addition, there was a papovavirus infection restricted to the cerebellum with predominant involvement of the internal granular cell layer; again, demyelinating lesions were not found elsewhere in the brain. Each of these patterns of brain involvement is rare. As the incidence of AIDS increases and patients are treated aggressively, the frequency of unusual neuropathologic patterns of opportunistic infections may be expected to increase.

Human immunodeficiency virus-1 infection of the nervous system: an autopsy study of 268 adult, pediatric, and fetal brains.

The central nervous system (CNS) of 221 adults and 31 infants or children with the acquired immunodeficiency syndrome (AIDS) was examined with immunocytochemistry for infectious agents and for human immunodeficiency virus-1 (HIV-1) antigen (gp41). Since the major risk factor in this population was intravenous drug abuse, there were more female and pediatric patients than in other neuropathology autopsy series. Although children had a different spectrum of pathologic changes, including less frequent opportunistic infections, women did not differ from men in terms of types or incidence of opportunistic infections, vascular disease, neoplasia, and subacute AIDS encephalitis (SAE). Subacute AIDS encephalitis was detected in 26% of adult and 48% of pediatric brains. Immunocytochemical analysis of 100 adult and 20 pediatric brains revealed gp41 immunoreactivity in 78% and 40%, respectively. Virtually all adult brains with SAE had gp41 immunoreactivity in macrophages and microglia. Even brains with no significant pathology had frequent gp41 immunoreactivity, especially in the basal ganglia. In pediatric brains, including cases with SAE, gp41 immunoreactivity was less abundant, suggesting the possibility of latent infection or viral clearance. Spinal cords with vacuolar myelopathy or corticospinal tract degeneration had only rare gp41-positive cells. Brains from 16 aborted fetuses from HIV-1-seropositive women were all negative for gp41 immunoreactivity, but 12 brains were positive for HIV-1 by the polymerase chain reaction. These results may indicate that HIV-1 infection in fetal brains is below the limits of detection of immunocytochemistry. The differences noted between adults and children suggest that adults more often have productive CNS HIV-1 infection.

Hyperinsulinemic hypoglycemia in adults with islet-cell hyperplasia and degranulation of exocrine cells of the pancreas.

Five adults with pancreatic islet-cell hyperplasia presenting as hyperinsulinemic hypoglycemia are reported. Additional insular lesions including nesidioblastosis, adenomatosis, and insulinoma were variably present. This apparent spectrum of islet-cell lesions has been rarely noticed in hypoglycemic adults, although it is a recognized cause of a similar clinical syndrome in children. B-cell hyperplasia was confirmed in all five cases by histochemistry, immunochemistry, and electron microscopy. In addition, nodules of eosinophilic exocrine cells, another recently recognized finding in similar cases, were present in all cases studied. Ultrastructural study revealed that these nodules were composed of degranulated acinar cells. These acinar changes may provide a diagnostic aid in cases of pancreatic endocrine hyperplasia. Consideration of the embryologic development of the pancreas suggests that this spectrum of islet-cell hyperplasia and acinar cell change is due to neoformation of islets from ducts. The etiologic factors of such proliferation are still unknown.

Central nervous system pathology in pediatric AIDS.

Children with AIDS frequently have neurological manifestations due to complications of immunodeficiency or intrinsic effects of human immunodeficiency virus type 1 (HIV-1) on the central nervous system (CNS). The most common neurological disorders not directly related to HIV-1 infection include cerebrovascular disease and lymphoma. Global anoxic-ischemic and necrotizing encephalopathies are frequent, while CNS hemorrhages and arteriopathies are less frequent. Opportunistic CNS infections are uncommon, limited predominantly to monilial and cytomegaloviral encephalitides. Only a few cases of CNS toxoplasmosis have been reported in children. CNS lymphomas often occur in the setting of systemic polymorphous, polyclonal B-cell proliferations that have been associated with Epstein-Barr virus infection. Intrinsic effects of HIV-1 on the CNS include microcephaly, diffuse gliosis, basal ganglia mineralization, HIV encephalitis, and corticospinal tract degeneration. Although viral antigens can be detected in microglia and multinucleated cells in HIV encephalitis, most of the CNS effects of HIV-1 infection cannot be attributed to detectable levels of viral antigen, suggesting that the pediatric CNS is unusually susceptible to low-level HIV-1 infection or to systemic effects of HIV-1 infection, possibly mediated by soluble factors, including the inflammatory cytokines, interleukin-1 beta, and tumor necrosis factor-alpha, which have been shown to be increased in serum and cerebrospinal fluid of children with AIDS.

Muscarinic receptor-dependent activation of phospholipase C in the developing human fetal central nervous system.

The coupling of muscarinic-cholinergic receptors (mAChR) to adenylate cyclase and phospholipase C (PLC) second messenger systems has been demonstrated in many animal species. However, little is known about this association in the developing human central nervous system. Because of the proposed role of acetylcholine in the regulation of development and differentiation of neural cells, an understanding of these relationships during human fetal development gains importance. We report, in this communication, the coupling of mAChR with PLC in the human fetal brain. This coupling was determined using two independent approaches that relied upon estimating the accumulation of inositol phosphates (IPs) and cytidine diphosphate diacylglycerol (CDP-DAG). Carbachol treatment of brain slices, in the presence of lithium, resulted in the accumulation of IPs. Analysis of the kinetics of this accumulation showed that IP3 and IP2 increased rapidly, reaching a peak or plateau before IP. The results also showed that agonist-stimulated PLC produced two second messengers, IP3 and DAG. The production of DAG was strongly supported by the carbachol-dependent increase of CDP-DAG. The accumulation of IP and CDP-DAG was dependent on agonist concentration. The obtained EC50 values were approximately: carbachol 47 microM; acetylcholine 6 microM; and oxotremorine 25 microM. Unexpectedly, all three agonists demonstrated a similar efficacy. The cholinergic stimulation of inositide hydrolysis appears to be the result of activation of the m1 muscarinic receptor.

Human fetal myelinated organotypic cultures.

We have previously reported the establishment of organotypic cultures derived from human fetal brain tissue. Although these cultures permit the testing of multiple hypotheses about normal human neurodevelopment and neuropathologic conditions, they have the limitation of not being myelinated and therefore preclude the study of questions related to myelinogenesis and diseases of myelin. In the current communication, we describe recent developments that allow us to overcome this limitation and permit the establishment of a myelinated organotypic culture model. Sections of dorsal column dissected from the lumbar spinal cord of human fetuses ranging in age 21-23 weeks of gestation were placed in culture. The explants were maintained for up to 12 weeks during which time they were characterized and shown to express a number of CNS cell-type-specific markers including glial fibrillary acidic protein (astrocytes), nerve growth factor receptor and neurofilament protein (neurons), CD68 (microglia), and myelin basic protein, HNK-1 and galactocerebroside (oligodendrocytes). In addition, lectin histochemistry using Ricinus communis agglutinin-1 detected microglia and endothelial cells. Upon explantation, abundant myelin was seen by electron microscopy in the cultures. Although during the culture period there was degradation of myelin, there was also evidence of maintenance of intact myelin sheaths around small caliber axons and de novo myelin synthesis. This model system may permit the further use of human organotypic cultures to investigate issues related to neurodevelopment and to pathologic conditions including those relevant to dysmyelination and demyelination.

Muscarinic receptor-dependent activation of phospholipase C in human fetal central nervous system organotypic tissue culture.

The coupling of muscarinic-cholinergic receptors (mAchR) with the phospholipase C (PLC) second messenger system has been demonstrated in central nervous system (CNS) tissue of many animal species. However, little information exists regarding this association in the developing human CNS. Due to the suggested role of acetylcholine in the regulation of development and differentiation of neural cells, the knowledge of these relationships during human fetal development acquires singular importance. Because of this, we examined the cholinergic stimulation of PLC in human fetal CNS organotypic tissue cultures. Agonist treatment of cultures, in the presence of lithium, resulted in a 4-6-fold increase in inositol phosphates formation. This increase was caused principally by the formation of inositol phosphate (IP). However, kinetic studies demonstrated that the levels of IP2, IP3 and IP4 also increased rapidly after stimulation reaching maximum levels before IP. These results support the hypothesis that muscarinic receptor activation results in an increase in the hydrolysis of PIP2. The inositol phosphate formation was dependent on agonist concentration. The obtained EC50 values were approximately 57 +/- 15 microM for carbachol, 8 +/- 2 microM for acetylcholine and 49 +/- 15 microM for oxotremorine. The agonist-dependent formation of inositol phosphates was inhibited by the muscarinic antagonists atropine and pirenzepine. Pirenzepine inhibited carbachol stimulation with high affinity (Ki = 2.90 +/- 1.15 nM), indicating that PLC activation is the result of activation of the m1 subtype of muscarinic receptors. Treatment of cultures with pertussis toxin did not result in inhibition of agonist-dependent activation of PLC. This result suggests that the m1 muscarinic receptor is coupled to PLC through Gq.

HIV infection of human fetal neural cells is mediated by gp120 binding to a cell membrane-associated molecule that is not CD4 nor galactocerebroside.

HIV infection of central nervous system (CNS) tissue is a common finding in both adult and pediatric AIDS. Because most children are believed to be infected perinatally, we have developed a model of HIV CNS infection that utilizes explant organotypic cultures of human fetal CNS tissue. Using this model we previously reported that both lymphocytotropic and monocytotropic HIV isolates infect microglia and astrocytes. However, the mechanism by which HIV infects these cells remains to be elucidated. We have observed that neural cell infection in these cultures may be the result of receptor-mediated endocytosis. In order to confirm this observation and to determine the ligand responsible for this process, organotypic cultures were exposed to untreated HIV, HIV pretreated with soluble CD4 (sCD4) or, as a control, heat-inactivated HIV. To address the question of a putative receptor for HIV infection, CNS cultures were either untreated or pretreated with gp120 or with the deglycosylated form of this protein. Other cultures were treated with antibodies to CD4 (anti-T4A) or to galactocerebroside (GC). Results demonstrate that pretreatment of either HIV with sCD4 or CNS cultures with gp120 significantly inhibits HIV infection. The inhibition of infection was demonstrated by a reduction in the number of cells positive for HIV proteins and by decreases in HIV proviral DNA and p24 production. Pretreatment of CNS cultures with deglycosylated gp120, anti-T4A or anti-GC antibodies did not inhibit HIV infection. These data suggest that HIV gp120 is needed for binding to a surface molecule on CNS cells that is not CD4 nor GC and that this molecule may function as a receptor and lead to infection of neural cells.

Large hypothalamic and optic chiasm gliomas in infants: difficulties in distinction.

Hypothalamic and optic chiasm gliomas may be indistinguishable clinically, radiographically, and pathologically. Ten children with giant gliomas of the hypothalamus and optic pathway, all under age 2 years, had masses greater than 3 cm in diameter. Pathologically all proven cases (seven) were cytologically benign fibrillary astrocytomas. Previous authors have recognized the difficulty in distinguishing these lesions; in this series, using previously suggested criteria, masses of optic chiasm could not be differentiated from hypothalamic origins. Likewise, at surgery and autopsy, the origin of these large masses was indeterminate. These tumors were more aggressive, invasive, and less responsive to therapy than the relatively benign orbital and optic nerve gliomas of older children and adults.

Atypical monoclonal plasma cell hyperplasia of the central nervous system: precursor of plasmacytoma with evolutionary considerations.

Hematopoietic proliferations rich in plasma cells rarely occur within the central nervous system without the involvement of other organ systems. Depending on their histological pattern and cellular composition, several different terms, including plasmacytoma, plasma cell granuloma, hyalinizing plasmacytic granulomatosis, and inflammatory meningioma, are used for these lesions. We report a left temporal dural lesion composed of plasma cells, lymphocytes, histiocytes, and rare eosinophils with hyaline changes and a suggestion of follicle formation, which stained predominantly for IgG and kappa light chains. This lesion arose in an otherwise healthy 52-year-old woman. Free kappa light chains without a monoclonal peak were found in the urine. We are aware of only two other heterogeneous, predominantly plasmacytic, solitary dural lesions that were found to be monoclonal on immunohistochemical examination. The label atypical monoclonal plasma cell hyperplasia appears to suit the morphological characteristics of our lesion. We suggest that a spectrum of solitary plasmacytic lesions may occur within the central nervous system and that atypical plasma cell hyperplasias have the potential to evolve into plasmacytoma. The preneoplastic nature of this lesion and its potential for evolution to malignant myeloma should be considered when planning treatment and lifelong follow-up for patients.

Etiology and pathophysiology of autistic behavior: clues from two cases with an unusual variant of neuroaxonal dystrophy.

Two unrelated individuals with autistic behavior had numerous swollen axon terminals (spheroids) located in specific brain regions relevant to their behavioral symptoms. Spheroids are characteristic of neuroaxonal dystrophy, but the clinical profile and anatomic distribution of the lesions in these two patients differed from those of previously described patients with neuroaxonal dystrophy. Spheroids were numerous in the sensory nuclei of the spinal cord and medulla, specific nuclei and the reticular formation of the brainstem tegmentum, hypothalamus, anterior and dorsomedial thalamus, hippocampus, and cingulate and orbitofrontal cortices. Spheroids were sparse in the primary and association cortices and basal ganglia and absent in the hemispheric white matter. Cerebellar atrophy was present in both cases but associated with spheroids in only one case. These cases represent a new variant of neuroaxonal dystrophy in which behavioral symptoms characteristic of autism dominated the clinical picture. Neuroaxonal dystrophy should be included in the list of diseases that may be found in persons with autism.

Intranuclear inclusion bodies in an elderly demented woman: a form of intranuclear inclusion body disease.

Intranuclear inclusion body disease (INIBD) is a rare neuropathological entity characterized by eosinophilic intranuclear bodies in neurons and/or glia. While this disease generally occurs in children, in whom it presents as a multiple systems degeneration, a few adult cases are also described. Only 4 previously reported adult cases have had an associated dementia and all of these patients had additional significant neurological abnormalities. We report a 72-year-old woman with primary degenerative dementia in whom intranuclear inclusion bodies (INIB) were a major neuropathologic finding. The INIB were most easily found in astrocytes of Alzheimer II type, which had proliferated in the cortex and white matter. Occasional neurons were affected. The inclusions consisted of 13 nm diameter filaments associated with amorphous electron-dense material, arranged in a random pattern without lattice formation. They did not stain with antibodies against all 3 neurofilament subunits, glial fibrillary acidic protein, tau-1 protein, vimentin, keratin or actin. We conclude that INIBD is a rare substrate of primary degenerative dementia in elderly patients.