The role of quantitative electromyography (EMG) in horses suspected of acute and chronic grass sickness

REASONS FOR PERFORMING THE STUDY

Clinical evidence of motor neuron involvement in equine grass sickness (EGS) has not been reported.

HYPOTHESIS

Quantitative electromyography (EMG) analysis can elucidate subtle changes of the lower motor neuron system present in horses with EGS, performed ante mortem.

METHODS

Fourteen horses diagnosed clinically with acute, subacute or chronic EGS were examined and quantitative EMG performed. Previously published data on healthy horses and horses with proven lower motor neuron disease (LMND) were used as controls. In 8 horses post mortem examination was performed, and in 7 muscle biopsies of the lateral vastus muscle underwent histopathology and morphometry.

RESULTS

Clinical electrophysiological evidence of neuropathy was present in 12 horses. Analysis of data from the first 4 horses resulted in 95% confidence intervals (CI) of nontransformed data for motor unit action potential (MUP) duration in subclavian, triceps and lateral vastus muscle of 11.0-13.7, 14.8-20.3 and 12.2-17.2 msecs, respectively, and for MUP amplitude 291-453, 1026-1892 and 957-1736 microV, respectively. For number of phases the 95% CI was 3.6-4.4, 2.9-3.6 and 2.9-3.4, respectively, and for number of turns 5.0-6.5, 4.3-5.3 and 3.7-4.6, respectively. No changes in duration of insertional activity were measured. Pathological spontaneous activity was observed in all horses. EGS as evidenced by degenerative changes in the autonomic ganglia in combination with minor degenerative changes of the spinal lower motor neurons was observed on post mortem examination in all 8 available autopsies. In muscle biopsies of 4 out of 7 horses changes consistent with slight neurogenic atrophy were found.

CONCLUSIONS AND POTENTIAL RELEVANCE

EMG results demonstrated the presence of a neuropathy of skeletal muscles in all horses suspected to have EGS. The combination of clinical and electrophysiological evidence may aid differential diagnosis of neurogenic disease in cases of weight loss and colic.

Fatal disseminated hemorrhagic toxoplasmic encephalitis as the initial manifestation of AIDS

A 28-year-old woman presented with progressive coma after being asymptomatic for 1 year after the demonstration of seropositivity for human immunodeficiency virus and high serum immunoglobulin G toxoplasma titers. Computed tomographic scanning showed multiple rounded cerebral hemorrhages and massive cerebral edema. Postmortem examination disclosed Toxoplasma gondii cysts scattered throughout the brain. An overwhelming fatal toxoplasmosis associated with multiple cerebral hemorrhages may be the first presentation of the acquired immunodeficiency syndrome. We raise the possibility that frequent neuroradiological monitoring may be indicated in asymptomatic human immunodeficiency virus-infected patients with high immunoglobulin G toxoplasma titers.

The diagnostic difficulties of meningeal and intracerebral plasma cell granulomas?presentation of three cases

Meningeal and intracerebral plasma cell granulomas are uncommon inflammatory lesions of unknown etiology. In this paper the diagnostic difficulties in two patients with meningeal plasma cell granuloma and one patient with intracerebral plasma cell granuloma are described. The first patient had an intracranial extra-axial lesion, which was first diagnosed as a meningioma. One and a half years later she underwent a second resection for recurrent tumor growth and the diagnosis of a meningeal plasma cell granuloma was made. The second patient was treated for a central nervous system B-cell lymphoma but proved to have an intracerebral plasma cell granuloma in retrospect 11 years later. In the third patient tuberculous meningitis was considered to be the most likely diagnosis because infratentorial contrast-enhanced thickened meninges (pachymeningitis) were found together with a high protein level in the cerebrospinal fluid and a positive Mantoux test. However, pathological examination of an extra-axial, cervical lesion that was operated upon revealed a meningeal plasma cell granuloma. These cases show the importance of diagnosing a meningeal or intracerebral plasma cell granuloma correctly, since it has both therapeutical and prognostic implications.

S-phase fraction, 5-bromo-2'-deoxy-uridine labelling index, duration of S-phase, potential doubling time, and DNA index in benign and malignant brain tumors

Seventy-one histologically malignant brain tumors, 52 histologically benign brain tumors, and 14 cerebral metastases were characterized according to DNA content and proliferative capacity. DNA ploidy, DNA index (DI), S-phase fraction (SPF), 5-bromo-2'-deoxy-uridine (BrdUrd) labelling index (LI), duration of S-phase (Ts), and potential doubling time (Tpot) were assessed by flow cytometry (FCM). In histologically benign tumors, a high percentage of DNA diploid tumors and a low proliferative capacity in DNA diploid tumors were found. Histologically malignant tumors and cerebral metastases were both found to be characterized by a low percentage of DNA diploid tumors and a high proliferative capacity in DNA diploid tumors. The proliferative capacity of DNA aneuploid benign tumors and that of DNA aneuploid malignant tumors, however, appeared not to differ significantly. The number of DNA aneuploid tumors was small. Duration of S-phase was short (range 3.9-4.7 hr) and appeared not to differ between the three groups. From this, the observed differences in Tpot values should be accredited mainly to differences in LI. High-grade as well as low-grade gliomas both appeared to be characterized by malignant (FCM) features, i.e., 1) a high percentage DNA aneuploidy, 2) a high mean DI (for DI > 1), and 3) a high proliferative capacity.

Creutzfeldt-Jakob disease 38 years after diagnostic use of human growth hormone

A 47 year old man is described who developed pathology proven Creutzfeldt-Jakob disease (CJD) 38 years after receiving a low dose of human derived growth hormone (hGH) as part of a diagnostic procedure. The patient presented with a cerebellar syndrome, which is compatible with iatrogenic CJD. This is the longest incubation period described so far for iatrogenic CJD. Furthermore, this is the first report of CJD after diagnostic use of hGH. Since the patient was one of the first in the world to receive hGH, other cases of iatrogenic CJD can be expected in the coming years.

Growth of cultured human glioma tumour cells can be regulated with histamine and histamine antagonists

The 50% survival time for low grade astrocytomas is 50 months and for high grade astrocytomas it is 13 months, underlining the need for new therapies. Several reports show that in vivo histamine antagonists cause retardation of tumour growth in some animal models and prolonged survival in cancer patients. Therefore we have tested the growth modulating effects of histamine and histamine antagonists on human glioma cultures. Twelve freshly excised human gliomas were cultured and tested for their in vitro sensitivity to histamine and histamine antagonists. Four continuous glioma cell lines were used to confirm the glioma-specificity of the effects observed in the primary cell lines. In low serum concentration (0 or 1%) the growth of 5/9 primary glioma-derived cultures could be stimulated with 0.2 mM histamine, and in 4/5 cases with 0.2 microM histamine. One mM of the histamine H2-receptor antagonist cimetidine could inhibit the growth of 4/5 primary glioma cultures when tested in 1% human AB serum, and of 6/13 cases when tested in 1% FCS. Lower concentrations (down to 1 microM) were less effective. The histamine H1-receptor antagonist pyrilamine gave variable results. The specificity of the effects is indicated by the absence of a generalised toxic effect, by the observation that the antagonist-induced inhibition could be reversed with histamine, and by the correlation of the obtained cimetidine-induced growth inhibition with the maximal growth rate of the primary cell lines in 10% FCS. The observed cimetidine-induced inhibition of the in vitro proliferation of gliomas suggests that cimetidine is a relevant candidate for the in vivo growth inhibition of these tumours.

Thickness of endoneurial vessel basal lamina area in chronic idiopathic axonal polyneuropathy

For chronic idiopathic axonal polyneuropathy (CIAP), even after extensive evaluation, no cause has yet been found. Considering the age and sex distribution of patients with this disease, it is possible that vascular disease plays a role in the development of this polyneuropathy. As endoneurial vessel abnormalities can be related to ischemia, we investigated endoneurial vessels in sural nerve biopsies of 18 patients with CIAP. As controls we used sural nerves of 4 patients with diabetes mellitus, 6 patients with hereditary motor and sensory neuropathy type II (HMSN type III) and 10 autopsy cases. Basal lamina area thickness, endothelial cell area, lumen area, and the number of basal laminae, endothelial cells and periendothelial cell nuclei were investigated. Basal lamina area thickness, endoneurial cell area and number of endothelial cell nuclei in CIAP were increased in comparison with HMSN type III, whereas the basal lamina area thickness of patients with CIAP and diabetes mellitus were in the same range. The structure of the basal lamina area in CIAP differed from diabetes mellitus; in diabetes mellitus there was a larger number of lamellae, whereas in CIAP there was an increase in collagen. There was no correlation between basal lamina area thickness and age. In CIAP patients with peripheral vascular disease of the legs, basal lamina area thickness was increased. The relation between basal lamina area thickening and peripheral vascular disease of the legs in CIAP may indicate a role for ischemia in the development of this polyneuropathy.

Contact laser-assisted neuroendoscopy can be performed safely by using pretreated 'black' fibre tips: experimental data

BACKGROUND AND OBJECTIVE

Laser-assisted endoscopic neurosurgery by using conventional fibres requires the use of high-power laser light. Because this is potentially hazardous, we developed a pretreated fibre tip and evaluated tissue effects in vitro and in vivo.

STUDY DESIGN/MATERIALS AND METHODS

By applying a highly absorbing coating to the front of the ball tip, almost all laser light is transformed into thermal energy, instantly producing ablative temperatures at the tip itself. The temperature distribution was examined by using an in vitro thermal imaging technique. The in vivo effect on rabbit cerebral tissue was examined macroscopically and histologically.

RESULTS

By using a conventional fibre tip, ablation was not observed, despite the use of high energy and power (20 W for 10 seconds), whereas histology and thermal imaging demonstrated deleterious effects deeply into the cerebral tissue. By using the coated fibre tip, ablation was observed at low energy and power (1 W for 1 second) with thermal effects restricted to superficial structures.

CONCLUSIONS

We show that laser-assisted neuroendoscopy can only be considered to be safe when pretreated "black" fibre tips are used, as laser light damages deep structures.

Recurrent subdural haematoma as the primary and sole manifestation of chronic lymphocytic leukaemia

An 81-year-old man with a recurrent subdural haematoma as the first and only manifestation of chronic lymphocytic leukaemia (CLL) is described. Microscopic examination of the encapsulated haematoma showed leukaemic infiltration and the diagnosis was confirmed by bone marrow aspiration and by pathological examination of the brain at autopsy.

Prognostic relevance of cell proliferation markers and DNA-ploidy in gliomas

The prognostic significance of clinically, histologically and flow cytometrically derived parameters was assessed in 49 glioma patients. With flow cytometry, DNA-index, S-phase fraction (SPF), 5-bromo-2'-deoxyuridine (BrdUrd)-labelling index (LI), and potential doubling time (Tpot) were determined. After univariate analysis of clinical variables such as, age, seizures as initial symptom, and duration of first symptom were found to be significantly associated both with proliferation rate and with local progression free survival (LPFS). Cytomorphological features such as, the presence or absence of mitosis, necrosis, and endothelial proliferation, were separately analysed and appeared to be significantly associated with LPFS. With respect to the cell proliferation markers, we observed a longer LPFS to be associated with a low SPF, a low LI, and a short Tpot. We did not observe a significant association between DNA-ploidy and LPFS. After multivariate analysis both of high and of low grade tumours, we found that neither LI, SPF, nor age had additional prognostic significance for cells in mitoses. We also demonstrated, that necrosis and endothelial proliferation had no additional prognostic significance to that for cells in mitoses. In the subgroup of low grade gliomas, in contrast to high grade gliomas, we noted prognostic significance for LI. We concluded, that i) the presence or absence of cells in mitoses was the strongest single prognosticator in gliomas, ii) in low grade gliomas LI holds prognostic significance.

Arteriovenous malformation of the vein of Galen in three neonates: emphasis on associated early ischaemic brain damage

Vein of Galen malformation is a rare intracranial disorder in newborns. In recent years the survival rate has improved due to improvement in endovascular treatment of this abnormality. We describe three neonates with a vein of Galen malformation for whom treatment was not attempted because of associated severe cerebral damage, of antenatal origin in two and of perinatal origin in the other. Autopsy was performed in two neonates. Periventricular leukomalacia was present in both cases, associated in one case with cortical infarction, gliosis and atrophy.

CONCLUSION

We recommend careful evaluation of associated cerebral damage prior to attempted treatment of the vein of Galen malformation.

Expression and regulation of voltage-gated sodium channel beta1 subunit protein in human gliosis-associated pathologies

Auxiliary beta1 subunits of voltage-gated sodium channels (NaChs) critically regulate channel activity and may also act as cell adhesion molecules (CAMs). In a recent study we have shown that the expression of beta1 NaCh protein is increased in reactive astrocytes in a rat epilepsy model of mesial temporal lobe epilepsy. The present study was undertaken to examine whether changes of NaCh beta1 subunit protein expression are also associated with structural changes occurring in human reactive astrocytes under different pathological conditions in vivo, as well as in response to changing environmental conditions in vitro. Strong beta1 astroglial immunoreactivity was present in human brain tissue from patients with astrogliosis. The over-expression of beta1 protein in reactive glia was observed in both epilepsy-associated brain pathologies (temporal lobe epilepsy, cortical dysplasia), as well as non-epileptic (cerebral infarction, multiple sclerosis, amyotrophic lateral sclerosis, meningo-encephalitis) disorders. The up-regulation of beta1 subunit protein in astrocytes can be reproduced in vitro. beta1 protein is highly expressed in human astrocytes cultured in the presence of trophic factors, under conditions in which they show morphology similar to the morphology of cells undergoing reactive gliosis. The growth factor-induced overexpression of beta1 protein was abrogated by PD98059, which inhibits the mitogen-activated protein kinase pathway. These findings demonstrate that the expression of NaCh beta1 subunit protein in astrocytes is plastic, and indicate a novel mechanism for modulation of glial function in gliosis-associated pathologies.

A novel Gerstmann-Sträussler-Scheinker disease mutation defines a precursor for amyloidogenic 8 kDa PrP fragments and reveals N-terminal structural changes shared by other GSS alleles

To explore pathogenesis in a young Gerstmann-Sträussler-Scheinker Disease (GSS) patient, the corresponding mutation, an eight-residue duplication in the hydrophobic region (HR), was inserted into the wild type mouse PrP gene. Transgenic (Tg) mouse lines expressing this mutation (Tg.HRdup) developed spontaneous neurologic syndromes and brain extracts hastened disease in low-expressor Tg.HRdup mice, suggesting de novo formation of prions. While Tg.HRdup mice exhibited spongiform change, PrP aggregates and the anticipated GSS hallmark of a proteinase K (PK)-resistant 8 kDa fragment deriving from the center of PrP, the LGGLGGYV insertion also imparted alterations in PrP's unstructured N-terminus, resulting in a 16 kDa species following thermolysin exposure. This species comprises a plausible precursor to the 8 kDa PK-resistant fragment and its detection in adolescent Tg.HRdup mice suggests that an early start to accumulation could account for early disease of the index case. A 16 kDa thermolysin-resistant signature was also found in GSS patients with P102L, A117V, H187R and F198S alleles and has coordinates similar to GSS stop codon mutations. Our data suggest a novel shared pathway of GSS pathogenesis that is fundamentally distinct from that producing structural alterations in the C-terminus of PrP, as observed in other prion diseases such as Creutzfeldt-Jakob Disease and scrapie.

Prion diseases can be sporadic, infectious or genetic. The central event of all prion diseases is the structural conversion of the cellular prion protein (PrP^C) to its disease associated conformer, PrP^Sc. Gerstmann-Sträussler-Scheinker Disease (GSS) is a genetic prion disease presenting as a multi-systemic neurological syndrome. A novel mutation, an eight amino acid insertion, was discovered in a young GSS patient. We created transgenic mice expressing this mutation and found that they recapitulate key features of the disease; namely PrP deposition in the brain and a low molecular weight proteinase K (PK) resistant internal PrP fragment. While structural investigations did not reveal a gross alteration in the conformation of this mutant PrP, the insertion lying at the boundary of the globular domain causes alterations in the unstructured amino terminal portion of the protein such that it becomes resistant to digestion by the enzyme thermolysin. We demonstrate by kinetic analysis and sequential digestion that this novel thermolysin resistant species is a precursor to the pathognomonic PK resistant fragment. Analysis of samples from other GSS patients revealed this same signature, suggesting a common molecular pathway.

Absence of characteristic features in two patients with inclusion body myositis

According to recently published criteria a diagnosis of definite sporadic inclusion body myositis is made if the typical histopathological abnormalities (rimmed vacuoles and abnormal accumulations of proteins, in addition to mononuclear cell infiltrates) are present. The two women described here presented with myositis which was unresponsive to treatment. Patient 1 had features of non-progressive sporadic inclusion body myositis clinically, whereas patient 2 had a very slowly progressive limb girdle syndrome. The cryostat sections of the first biopsies did not show rimmed vacuoles, even in retrospect. Only a repeated biopsy, 12 years after presentation in one patient and 18 years after presentation in the other, disclosed the typical features of sporadic inclusion body myositis. The initial absence of abnormal fibres probably represents a real absence or scarcity rather then a sampling error due to a multifocal nature of the histological abnormalities. It is of importance for the clinician to realise that some patients with myositis unresponsive to treatment, even if both clinical and histological features do not suggest sporadic inclusion body myositis, may prove to have the disease on repeated histopathological examination.

Fast fluid-attenuated inversion recovery (FLAIR) compared with T2-weighted spin-echo in the magnetic resonance diagnosis of mesial temporal sclerosis

RATIONALE AND OBJECTIVES

The authors compare coronal fast fluid-attenuated inversion recovery (FLAIR) with coronal T2-weighted spin-echo (SE) magnetic resonance (MR) techniques in the diagnosis of mesial temporal sclerosis (MTS).

METHODS

In this prospective study, the authors assessed MR scans of 30 patients with drug-resistant temporal lobe epilepsy (based on clinical symptomatology and electroencephalographic registrations) with MR features suggestive of MTS. MR scans of age-, sex-, and scanner-matched patients, referred for MR assessment of white matter disease, without a history of epilepsy and with no visible abnormalities on MR, were used as controls. In 16 patients the MR diagnosis was confirmed by histologic abnormalities consistent with MTS. Coronal T2 SE and FLAIR images of patients and controls were presented to two experienced radiologists in random order for independent blinded review. Hippocampal and associated extrahippocampal temporal lobe abnormalities were used for the diagnosis of MTS.

RESULTS

The sensitivity of observer A was 97% for the T2 SE sequence and 100% for the FLAIR; the specificity of observer A for both techniques was 100%. The sensitivity of observer B was 53% for T2 SE and 83% for FLAIR; the specificity for observer B was 93% for the T2 SE and 100% for FLAIR.

CONCLUSION

Coronal FLAIR images provide a similar or increased yield in the detection of MTS compared with T2-weighted SE images.

Giant cell ependymoma of the thoracic spine: pathology case report

INTRODUCTION AND IMPORTANCE: Spinal ependymomas are slow-growing lesions that comprise the majority of primary spinal cord neoplasms. When surgery is indicated, the extent of tumor removal is most prognostic for long-term survival. Unusual histological subtypes can make intraoperative diagnosis spurious, possibly altering the surgical approach from gross total resection for ependymomas to debulking for high-grade astrocytomas.

CLINICAL PRESENTATION

We describe a 67-year-old woman with a thoracic spine intramedullary giant cell ependymoma. She presented with decreased lower extremity sensation leading to unsteadiness and an eventual fall. A physical examination revealed lower extremity hyperreflexia and ankle clonus, but no clear sensory level. Magnetic resonance imaging demonstrated an intramedullary T1 and T2 hypointense, homogenously enhancing lesion at T8 with extensive cephalad and caudal edema.

INTERVENTION AND TECHNIQUE

A laminectomy at T8 to T9 afforded gross total resection of the lesion that had a clear cleavage plane with normal spinal cord. Intraoperative pathology suggested a high-grade glioblastoma, but final section showed sporadic giant cells with marked pleomorphism, uniform immunofluorescence staining with both glial fibrillary acidic protein and cluster of differentiation 99, and high MIB-1 index. Electron microscopy showed "zipper-like" junctions. There were no detected genomic abnormalities consistent with glioblastoma.

CONCLUSION

We present this first reported case of thoracic spine giant cell ependymoma alongside scant literature yielding 1 case in the cervical spine and 2 cases at the filum terminale. Those cases had benign courses, whereas ours demonstrates a high degree of proliferation, making the malignant potential difficult to assess.

Ultraviolet-B induced hyperplasia and squamous cell carcinomas in the cornea of XPA-deficient mice

In Xeroderma Pigmentosum (XP) patients, due to a defective repair of UV-induced DNA damage, neoplastic changes occur in sunlight-exposed areas of the skin and eyes. There are seven complementation groups in XP (XP-A to XP-G). Recently, we have generated XPA-deficient mice (group-A XP) by gene targeting in embryonic stem cells. In order to evaluate UV-B sensitivity, XPA-deficient mice (n = 20), wild type (n = 7) and heterozygous mice (n = 13) were exposed to low daily doses of UV-B for 14 weeks at a cumulative dose of 22 kj m-2 (250-400 nm). For a period of 32 weeks, the mice were checked twice a week for the development of pathology. The UV-B treatment induced eye abnormalities in the XPA-deficient mice. Initially, photophobia was noticed, followed by a loss of transparency of the cornea, eventually affecting nearly all XPA-deficient mice (19 out of 20). In 12 out of 19 mice, the pathology progressed to give eye protrusion. Histology of these eyes showed hyperplasia and squamous cell carcinomas of the corneal epithelium. No eye-lesions were found in control (wild-type and heterozygous) mice that were exposed to the same UV-B dose. The corneal abnormalities found in the XPA-deficient mice appear to be similar to those found in human XP patients. These results confirm the role of the functional XPA gene in protecting the cornea from pathology by UV-B irradiation. In addition, they suggest that the XPA-deficient mouse is a suitable animal model for the study of XPA ocular disorders.

Bilateral temporal lobe necrosis after radiotherapy: confounding SPECT results

A patient with seizures and a contrast-enhancing temporal lesion after radiation therapy for a chondrosarcoma of the nasal septum is described. To differentiate between radiation necrosis and recurrent tumor, thallium-201 (201Tl) SPECT was used. 201Tl SPECT revealed high local accumulation suggesting tumor growth; however, pathologic examination demonstrated focal necrosis with reactive changes but without tumor. The 201Tl SPECT findings in this patient demonstrate a possible diagnostic pitfall in differentiating recurrent tumor from radiation necrosis.

MR contribution in surgery of epilepsy

The contribution of MR imaging in patients with drug-resistant epilepsy considered for surgical therapy is discussed. In this review we focus on: (a) focal abnormalities (mesial temporal sclerosis, focal migration disorders, hamartomatous lesions and low-grade tumours, phakomatosis and vascular malformations) associated with therapy-resistant partial epilepsy, requiring resective surgery; (b) abnormalities leading to generalized seizures that require more drastic surgical procedures, such as callosotomy and functional hemispherectomy; and (c) localisation of implanted depth-electrodes.

Mycotic encephalitis: predilection for grey matter

In mycotic infections of the brain three patterns of abnormality may be observed: meningitis, granuloma, and encephalitis. The first two, consisting of diffuse meningeal enhancement and mass lesion respectively, can easily be visualised by CT or MRI, but are nonspecific. The third pattern has been described histopathologically; as the clinical picture is nonspecific and the diagnosis is often unsuspected, especially in immunocompetent patients, acquaintance with the characteristic CT and MRI patterns of mycotic encephalitis may help in establishing the correct diagnosis, with important therapeutic consequences.

Distribution of cellular prion protein in normal human cerebral cortex--does it have relevance to Creutzfeldt-Jakob disease?

Creutzfeldt-Jakob disease and bovine spongiform encephalopathy are the best known forms of prion diseases. A basis for their pathogenesis is the transformation of normal prion protein to abnormal prion protein. This would mean that either loss of normal function or a gain of a toxic function of the prion protein would play a major role. Since the prime target for Creutzfeldt-Jakob disease in humans is the neocortex, and the intracortical distribution of the destructive process in prion diseases appears not to be haphazard, it may be that a clear cortical study of normal prion protein production in the premorbid human neocortex might contribute to insight in the pathogenesis of prion diseases. As no such study is available, we performed a detailed study in normal human cortex using immunohistochemistry for prion protein, in both frozen and vibratomised tissue, and in situ hybridisation for prion protein mRNA. We have found normal prion protein production mainly in the upper cortical neurons in neocortex and Purkinje cells in the cerebellum. This finding implicates that normal prion protein is more important as an anti-apoptotic signal in disease than abnormal prion protein is as a toxic substance.

Polar spongioblastoma: an immunohistochemical and electron microscopical study

A case is reported of a 9-year-old boy with a cerebral polar spongioblastoma. This neoplasm, first described by Russell and Cairns in 1947, is morphologically a distinct entity characterized by bipolar tumor cells with palisading nuclei. In the case under study immunoreactivity for neuron-specific enolase was found and ultrastructural features of developing neuronal elements were present. A neuro-endocrine nature was suggested by de Chadarévian et al. (1984) in a morphologically similar case. These findings are in contrast with the long-held view that the polar spongioblastoma is cytogenetically related to the embryonal radial glial cells.

Association between the PRNP 1368 polymorphism and the occurrence of sporadic Creutzfeldt-Jakob disease

Creutzfeldt-Jakob disease (CJD) is a rare transmissible neurodegenerative disorder. The etiology of sporadic form of CJD remains unsolved. In addition to the codon 129 polymorphism, polymorphisms in the non-coding region of PRNP are considered as important factors in sCJD development. To assess a possible association between PRNP 1368 SNP and sCJD, we compared the genotype, allele and haplotype frequencies of the 1368 SNP among 46 sCJD patients of Dutch origin with the respective frequencies in healthy controls. We detected a significant association between sCJD and 1368T/T genotype. A significant difference was also observed in 1368 alleles' distribution. In the haplotype analysis, haplotype 1368C-129G was associated with decreased risk of sCJD in Dutch population. Our findings support the hypothesis that genetic variations in the regulatory region of the PRNP gene may influence the pathogenesis of sCJD.

A case cluster of variant Creutzfeldt-Jakob disease linked to the Kingdom of Saudi Arabia

As of mid-2016, 231 cases of variant Creutzfeldt-Jakob disease-the human form of a prion disease of cattle, bovine spongiform encephalopathy-have been reported from 12 countries. With few exceptions, the affected individuals had histories of extended residence in the UK or other Western European countries during the period (1980-96) of maximum global risk for human exposure to bovine spongiform encephalopathy. However, the possibility remains that other geographic foci of human infection exist, identification of which may help to foreshadow the future of the epidemic. We report results of a quantitative analysis of country-specific relative risks of infection for three individuals diagnosed with variant Creutzfeldt-Jakob disease in the USA and Canada. All were born and raised in Saudi Arabia, but had histories of residence and travel in other countries. To calculate country-specific relative probabilities of infection, we aligned each patient's life history with published estimates of probability distributions of incubation period and age at infection parameters from a UK cohort of 171 variant Creutzfeldt-Jakob disease cases. The distributions were then partitioned into probability density fractions according to time intervals of the patient's residence and travel history, and the density fractions were combined by country. This calculation was performed for incubation period alone, age at infection alone, and jointly for incubation and age at infection. Country-specific fractions were normalized either to the total density between the individual's dates of birth and symptom onset ('lifetime'), or to that between 1980 and 1996, for a total of six combinations of parameter and interval. The country-specific relative probability of infection for Saudi Arabia clearly ranked highest under each of the six combinations of parameter × interval for Patients 1 and 2, with values ranging from 0.572 to 0.998, respectively, for Patient 2 (age at infection × lifetime) and Patient 1 (joint incubation and age at infection × 1980-96). For Patient 3, relative probabilities for Saudi Arabia were not as distinct from those for other countries using the lifetime interval: 0.394, 0.360 and 0.378, respectively, for incubation period, age at infection and jointly for incubation and age at infection. However, for this patient Saudi Arabia clearly ranked highest within the 1980-96 period: 0.859, 0.871 and 0.865, respectively, for incubation period, age at infection and jointly for incubation and age at infection. These findings support the hypothesis that human infection with bovine spongiform encephalopathy occurred in Saudi Arabia.