Ultrastructural examination is essential for diagnosis of papillary meningioma.

AIMS: Papillary meningioma is a rare meningeal tumour. To date only a few cases have been reported and their immunohistochemical features have not been fully documented. METHODS AND RESULTS: A 49-year-old woman presented with a 2-month history of headaches and memory disturbance. CT and MRI imaging showed an enhancing pineal mass with extension into the occipital lobes and invasion of the splenium. At surgery, the tumour was found to be tough and vascular with a well-defined capsule. No recurrence was noted 19 months after the operation. In another case a 44-year-old woman was admitted with 1-month history of headaches, poor memory, imbalance and diplopia. CT scan showed a large hyperdense, uniformly, enhancing mass within the middle cranial fossa at the petrous ridge. The tumour recurred 19 and 25 months after first resection. The histology of both tumours was similar. The neoplasms contained polygonal cells with a moderate amount of cytoplasm, rounded regular nuclei and distinct cell borders. The cells were arranged radially around the blood vessels (perivascular pattern) and a papillary pattern was seen only focally. Mitotic figures were moderately frequent. Immunohistochemistry showed that both tumours were immunoreactive to vimentin and NSE, whereas GFAP, CAM5.2, EMA, S100 protein and synaptophysin were negative. Electron microscopy revealed interdigitating cell processes, desmosomes and intermediate filaments. CONCLUSIONS: The histological and immunohistochemical features of these two tumours are complex and difficult to interpret. Although papillary meningiomas were considered in our initial differential diagnosis, the final conclusion was possible only when the ultrastructural features were revealed.

Primary CA1 and conditionally immortal MHP36 cell grafts restore conditional discrimination learning and recall in marmosets after excitotoxic lesions of the hippocampal CA1 field.

Common marmosets (Callithrix jacchus, n = 18) were trained to discriminate between rewarded and non-rewarded objects (simple discriminations, SDs) and to make conditional discriminations (CDs) when presented sequentially with two different pairs of identical objects signifying reward either in the right or left food well of the Wisconsin General Test Apparatus. After bilateral N-methyl-D-aspartate (0.12 M) lesions through the cornu ammonis-1 (CA1) field (7 microl in five sites), marmosets showed profound impairment in recall of CDs but not SDs, and were assigned to lesion only, lesion plus CA1 grafts and lesion plus Maudsley hippocampal cell line, clone 36 (MHP36) grafts groups matched for lesion-induced impairment. Cell suspension grafts (4 microl, 15-25 000 cells/microl) of cells dissected from the CA1 region of foetal brain at embryonic day 94-96, or of conditionally immortalized MHP36 cells, derived from the H-2Kb-tsA58 transgenic mouse neuroepithelium and labelled with [3H]thymidine, were infused at the lesion sites. The lesion plus MHP36 grafts group was injected five times per week with cyclosporin A (10 mg/kg) throughout testing. Lesion, grafted and intact control marmosets (n = 4-5/group) were tested on recall of SDs and CDs learned before lesioning and on acquisition of four new CDs over a 6-month period. Lesioned animals were highly impaired in recall and acquisition of CD tasks, but recall of SDs was not significantly disrupted. Both grafted groups of marmosets showed improvement to control level in recall of CDs. They were significantly slower in learning the first new CD task, but mastered the remaining tasks as efficiently as controls and were substantially superior to the lesion-only group. Visualized by Nissl staining, foetal grafts formed clumps of pyramidal-like cells within the denervated CA1 field, or jutted into the lateral ventricles. MHP36 cells, identified by beta-galactosidase staining and autoradiography, showed neuronal and astrocytic morphology, and were distributed evenly throughout the CA1 region. The results indicate that MHP36 cell grafts are as functionally effective as foetal grafts and appear to integrate into the host brain in a structurally appropriate manner, showing the capacity to differentiate into both mature neurons and glia, and to develop morphologies appropriate to the site of migration. These findings, which parallel the facilitative effects of foetal and MHP36 grafts in rats with ischaemic CA1 damage, offer encouragement for the development of conditionally immortal neuroepithelial stem cell lines for grafting in conditions of severe amnesia and hippocampal damage following recovery from cardiac arrest or other global ischaemic episodes.

Investigation of variant Creutzfeldt-Jakob disease and other human prion diseases with tonsil biopsy samples.

BACKGROUND: Prion diseases are associated with the accumulation of an abnormal isoform of cellular prion protein (PrPSc), which is the principal constituent of prions. Prions replicate in lymphoreticular tissues before neuroinvasion, suggesting that lymphoreticular biopsy samples may allow early diagnosis by detection of PrPSc. Variant Creutzfeldt-Jakob disease (variant CJD) is difficult to distinguish from common psychiatric disorders in its early stages and definitive diagnosis has relied on neuropathology. We studied lymphoreticular tissues from a necropsy series and assessed tonsillar biopsy samples as a diagnostic investigation for human prion disease. METHODS: Lymphoreticular tissues (68 tonsils, 64 spleens, and 40 lymph nodes) were obtained at necropsy from patients affected by prion disease and from neurological and normal controls. Tonsil biopsy sampling was done on 20 patients with suspected prion disease. Tissues were analysed by western blot to detect and type PrPSc, by PrP immunohistochemistry, or both. FINDINGS: All lymphoreticular tissues obtained at necropsy from patients with neuropathologically confirmed variant CJD, but not from patients with other prion diseases or controls, were positive for PrPSc. In addition, PrPSc typing revealed a consistent pattern (designated type 4t) different from that seen in variant CJD brain (type 4) or in brain from other CJD subtypes (types 1-3). Tonsil biopsy tissue was positive in all eight patients with an adequate biopsy sample and whose subsequent course has confirmed, or is highly consistent with, a diagnosis of variant CJD and negative in all patients subsequently confirmed to have other diagnoses. INTERPRETATION: We found that if, in the appropriate clinical context, a tonsil biopsy sample was positive for PrPSc, variant CJD could be diagnosed, which obviates the need for a brain biopsy sample to be taken. Our results also show that variant CJD has a different pathogenesis to sporadic CJD.

Structural and functional changes in skeletal muscle in anorexia nervosa.

Protein-energy malnutrition in anorexia nervosa is an under-recognised cause of muscle dysfunction. To characterise the skeletal myopathy that occurs in patients with severe anorexia nervosa, muscle function and structure were comprehensively examined in eight young adult female patients with severe (40%) self-induced weight loss. All of the patients showed impaired muscle function on strength and exercise measurement. The maximum voluntary contraction force for the patient group was significantly less than predicted values. Electromyography revealed myopathy in five of the patients, four of whom also had electro-physiological evidence of neuropathy. However, muscle biopsy specimens consistently showed myopathic changes with severe type 2 fibre atrophy but with no evidence of neuropathic changes. Ultrastructurally, there was separation and segmental loss of myofibrils and most biopsy samples contained abundant glycogen granules; we have previously reported that one of the most consistent biochemical abnormalities in these patients is impaired ischaemic lactate responses to forearm exercise. The result of severe protein-energy malnutrition on the musculo-skeletal system is a metabolic myopathy. Although the patients admitted to a variety of abnormal dieting behaviours, such as over-exercising and self-induced vomiting, no association was found between any of these and quantitative histological changes in the muscle biopsy samples. It is recommended that myopathy in anorexia nervosa be treated by instituting an appropriate refeeding programme.

HIV-associated brain pathology: a comparative international study.

Little is known about the frequency and variation of HIV-associated brain pathology in different geographical centres. To assess whether there is an association between the frequency of disease and demographic factors we examined the neuropathological findings in four European and two American cities. The cities included London, Edinburgh, Paris, Budapest, Baltimore and Newark. Information was collected on a total of 1144 cases. HIV encephalitis was the most common observation in all the centres. although its frequency varied between them (P < 0.01). Furthermore, there were significant differences (P < 0.001) between the various categories of exposure and the frequency of HIV encephalitis in Edinburgh and other centres. The occurrence of toxoplasmosis, progressive multifocal leukoencephalolpathy (PML) and cryptococcal infection also differed between the various centres (P < 0.01). None of the findings was attributable to age, sex, or ethnic origin, but the introduction of anti-retroviral treatment, such as Zidovudine, may have been important. Overall, this study highlights geographical variability and the potential importance for group of exposure and anti-retroviral medication as factors affecting the development of various HIV-associated brain lesions.

HIV-associated brain pathology in the United Kingdom: an epidemiological study.

OBJECTIVES: To examine the epidemiology of HIV-associated neuropathology in the United Kingdom and to investigate whether the prevalence of different forms of HIV-associated brain pathology varies with exposure category. DESIGN: The study was a cross-sectional survey; data was analysed from the Medical Research Council National AIDS Neuropathology database. SETTING: Information was gathered from throughout England, Scotland and Wales. SUBJECTS: Individuals who died from AIDS in the United Kingdom and had a postmortem examination. The database comprised 7% of all AIDS deaths in the United Kingdom between 1982 and 1993. MAIN OUTCOME: Neuropathological diagnoses based on internationally accepted neuropathological terminology of AIDS-related brain lesions. RESULTS: HIV encephalitis was the most prevalent pathological diagnosis, occurring in 25.3% [95% confidence interval (CI), 21.0-29.6] of the study sample. Statistically significant independent associations for the occurrence of HIV encephalitis were found for injecting drug use (odds ratio, 6.86; 95% CI, 2.91-16.17), and age less than 30 years at death (odds ratio, 3.58; 95% CI, 1.99-6.44). Vascular lesions were significantly higher among blood product recipients, 95% of whom were haemophiliacs. CONCLUSIONS: This was the first epidemiological investigation of HIV-associated brain pathology in the United Kingdom. HIV encephalitis appeared to occur more frequently in injecting drug users and those who died younger. Whereas the findings must be interpreted cautiously, one hypothesis was that differences in the route of transmission may have affected the manifestation of HIV-associated brain damage.

Predominant deposition of amyloid-beta 42(43) in plaques in cases of Alzheimer's disease and hereditary cerebral hemorrhage associated with mutations in the amyloid precursor protein gene.

Amyloid (A beta) deposition was investigated in cases of Alzheimer's disease and hereditary cerebral hemorrhage with amyloidosis, Dutch type, due to mutations in the amyloid precursor protein (APP) gene using the end-specific monoclonal antibodies BA27 and BC05 that recognize A beta 40 or A beta 42(43), respectively. In cases of APP717 mutation the predominant A beta species within plaques terminate at A beta 42(43) with relatively little A beta 40 being present. The total amount of A beta deposited as A beta 42(43) is significantly greater than in sporadic Alzheimer's disease, consistent with the suggestion that this mutation might influence the processing of APP so as to produce more of the highly aggregatable form, A beta 1-42. In cases of APP670/671 mutation the major peptide in plaques is also A beta 42(43), although the proportion of plaques containing A beta 40, and the total A beta load is similar to that in sporadic Alzheimer's disease. As in sporadic Alzheimer's disease, the vascular amyloid in APP670/671 and APP717 and in cases of hereditary cerebral hemorrhage with amyloidosis, Dutch type is predominantly A beta 40 in this latter disorder, however, parenchymal deposits are exclusively A beta 42(43). Although the various APP mutations may influence the type, quantity, and location of A beta deposited, the predominant, and possibly the initial, species deposited in the brain parenchyma is A beta 42(43).

Critical illness poly-neuropathy following severe hyperpyrexia.

Two patients developed critical illness polyneuropathy after severe hyperpyrexia. Fever was secondary to a phaeochromocytoma in one patient and sepsis in the other. These observations suggest that high fever may be one possible aetiology of critical illness polyneuropathy.

Neuronal loss in the hippocampus in Huntington's disease: a comparison with HIV infection.

The hippocampus is usually affected in primary dementias and the pathological changes may be severe. Knowledge of hippocampal pathology in HIV infection and Huntington's disease (HD), however, is extremely limited. A stereological technique (the optical "disector") has been used to assess neuronal populations in four areas of the hippocampus in 11 patients with HIV infection and in nine patients with HD. The HIV patients died without opportunistic infections or neoplasms affecting the brain; they had HIV encephalitis or minimal changes. The HD cases were all clinically diagnosed, had a positive family history and showed the characteristic lesions in the caudate nucleus. The neuronal counts were compared with those in nine controls. In the granule cell layer of the dentate, CA3 and CA4, there was no significant difference in the neuronal numerical density between the three groups. A striking difference between the HIV and HD groups was seen in the CA1 region. The neuronal numerical density in the CA1 area was significantly lower in the HD patients than in either the HIV patients or the controls (mean (SD) 37.5 (5.0); 70.1 (13.4); 57.9 (15.4) x 10(3) per mm3, p < 0.001 (Students' t test)). This difference represents a neuronal loss of 35%. In all four hippocampal areas the neuronal density was higher in the HIV group than in the controls but the differences were not significant and can be explained by the higher average age of the control group. These findings contribute to the understanding of the mechanism of dementia in both AIDS and in Huntington's disease.

Neuronal number and volume alterations in the neocortex of HIV infected individuals.

Substantial neuronal loss in the superior frontal gyrus in patients who have died of AIDS have been reported previously. This investigation examined the distribution of neuronal loss in three other neocortical areas and, alteration in neuronal volume in four neocortical areas. This was carried out using two stereological probes, the "disector" and the "nucleator". These recently developed methods provide estimations, regardless of size and shape, in real three-dimensional space, and are more efficient than conventional quantitation. The study was performed on 12 HIV infected individuals and nine controls. The HIV group had no neuropathological evidence of opportunistic infections or neoplasms, five had HIV encephalitis and the remaining seven had only minimal pathology. There was significant neuronal loss of 30% (p = 0.018) in the calcarine cortex (primary visual area), and loss of 18% in the superior parietal lobule which just failed to reach significance. This loss was not related to the presence of HIV encephalitis. The mean neuronal volume was increased in the occipital area by 29% (p = 0.028) and the frequency of large neurons (over 2000 microns 3) doubled in the frontal (p < 0.05) and parietal (p < 0.02) areas. The results confirm the hypothesis that HIV infection is associated with neuronal injury and death, and suggest that increase in neuronal size may be a feature of the cytopathology of this condition.

Survival and distribution of transplanted human IMR-32 neuroblastoma cells.

The visualisation of transplanted cell lines is essential to determine both their viability and possible functional properties. Fluorescent latex microspheres were used to label cultured human neuroblastoma IMR-32 cells prior to transplantation. IMR-32 cells were first rendered amitotic by treatment with mitomycin C and bromodeoxyuridine and subsequently incubated with fluorescent microspheres for 3 days. Cell suspensions were prepared from these cultures and transplanted into the cortex and hippocampus of male Sprague-Dawley rats bearing ibotenate lesions of forebrain cholinergic projections. The animals were perfused at 4, 8 and 12 weeks post-transplantation and tissue was prepared for electron and light microscopy. IMR-32 cells containing fluorescent microspheres were clearly visualised in cryostat sections at all time points. Greater survival was seen in the hippocampus, with evidence of migration of cells from the site of implantation. Macrophages were seen at the electron and light microscope level, and were distinct from the discrete fluorescent labelled IMR-32 cells. Ultrastructurally, transplanted IMR-32 cells resembled cells in vitro, with microspheres clearly distinguished within the cytoplasm. Fluorescent microspheres provide a simple and direct labelling technique suitable for long-term transplant experiments using characterised cell lines.

Neuronal loss in the frontal cortex in HIV infection.

In an attempt to elucidate the cause and mechanism of the dementia and other neurological disorders that can occur in HIV-1 infection, we have quantitatively assessed neuronal populations, by means of a stereological technique (the disector), in the frontal cortex of patients with HIV infection. Eleven of sixty-five brains in the Medical Research Council Central AIDS Brain Bank were selected for study. The selected patients died without opportunistic infection or neoplasm affecting the brain; they had HIV encephalitis or minimal changes. We compared their neuronal counts with those of eight control subjects (seven died of systemic illness, one of pontine haemorrhage which did not affect the cerebral hemispheres). The neuronal numerical density was significantly lower in the HIV group than in the control group (mean [SD] 307 [46] vs 499 [113] x 10(2) per mm3; p less than 0.001). This difference represents a loss of about 38%. There was no significant difference between the HIV subgroups, which suggests that neuronal loss occurs in cases of minor pathology as well as in HIV encephalitis. This finding contributes to the understanding of dementia in AIDS patients and has important implications for their future treatment.

The effects of cholinergic drugs and cholinergic-rich foetal neural transplants on alcohol-induced deficits in radial maze performance in rats.

Chronic alcohol (20% v/v in drinking water for 28 weeks) impaired acquisition of radial maze spatial and associative tasks by increasing both within-trial working and long-term reference memory errors; animals with high (above the median of 100 mg/100 ml) blood alcohol concentrations (BACs) during treatment were significantly more impaired than those with BACs below the median. Alcohol-treated rats showed improvements in radial maze performance after treatment with cholinergic agonists (arecoline and nicotine) and disruption with antagonists (scopolamine and mecamylamine) at low doses which did not affect controls. These effects were more pronounced for working than reference memory, and not manifest with the peripherally acting antagonists hexamethonium and N-methylscopolamine. Transplants into cortex and hippocampus of cholinergic-rich basal forebrain (BF) and ventral mesencephalon (VM) foetal neural tissue improved radial maze performance of alcohol-treated rats to control level over a period of 9-12 weeks after grafting. Cholinergic-poor foetal hippocampal (HC) grafts were without effect. BF and VM, but not HC, grafts showed dense acetylcholinesterase (AChE) staining, tyrosine-hydroxylase staining was most pronounced in VM sections and dopamine-beta-hydroxylase staining was minimal in all grafts. Choline acetyltransferase (ChAT) activity was significantly reduced in cortex and hippocampus of alcohol-treated rats, except those given cholinergic-rich transplants. Alcohol treatment also significantly reduced AChE-positive cell counts in the nucleus basalis, medial septal and diagonal band brain areas, at the sources of the forebrain cholinergic projection system (FCPS). Cortical levels of noradrenaline were significantly reduced in all alcohol-treated rats, regardless of transplant, whereas cortical dopamine content was significantly elevated in all rats receiving transplants, regardless of behavioural effect, but not in alcohol-treated controls. Forebrain serotonin levels were not significantly altered by grafting or alcohol treatment. These results suggest that damage to the FCPS, as shown by reduced ChAT activity in target areas, and reduced AChE cell counts in projection areas, played an important part in the radial maze deficits displayed by alcohol-treated rats, since these animals were sensitive to cholinergic drug challenge, and cholinergic-rich transplants from two different sites in foetal brain elevated ChAT activity and restored cognitive function. In contrast alcohol- or graft-induced alterations in other transmitter systems did not correlate with the pattern of behavioural deficit and recovery.

A comparative morphological and immunohistochemical study of testicular seminomas and intracranial germinomas.

A series of 10 classical testicular seminomas and 10 intracranial germinomas were reviewed and examined using immunohistochemical techniques. In particular, the staining profiles of the tumour cells and the nature of the mononuclear cell infiltrate at the two sites were studied and compared. The tumour cells in eight of the 10 intracranial germinomas and nine of the 10 seminomas exhibited positive staining with placental alkaline phosphatase. Only one intracranial germinoma showed evidence of human chorionic gonadotrophin expression. Tumour cells in all cases at both sites were negative for cytokeratin and vimentin. The lymphocytic infiltrate in both the testicular and intracranial tumours was similar, comprising T-cells and B-cells, the former predominantly. The presence of macrophages and granulomas in tumours at both sites was noted. These findings confirm the high degree of similarity of germinomas of intracranial and testicular origin, and support the hypothesis of a common derivation. We could find no evidence of differentiation of tumour cells at either site.

Cytogenetic abnormalities in human ependymomas.

The karyotypes of 4 human ependymomas have been determined. In one ependymoma, translocations involving chromosomes 9, 17 and 22 were observed together with the loss of the normal chromosome 17. A second ependymoma had many chromosomal alterations that included a translocation between chromosomes 1 and 2 and re-arrangements involving chromosome 17. No major consistent alterations were detected in the remaining 2 cases. Our karyotypes do not resemble the few previously published karyotypes of ependymomas, but had features, such as the alterations involving chromosome 17, that were similar to those of other brain tumours in children.