No evidence of asymptomatic variant CJD infection in immunodeficiency patients treated with UK-sourced immunoglobulin

Surveillance of 75 immunodeficiency patients exposed to UK-sourced immunoglobulin, including batches derived from donors who went on to develop vCJD, has not detected any clinical cases of vCJD, or of asymptomatic infection in 15 patients with available tissue samples of sufficient quality for testing.

Chordoma masquerading as a nerve root tumour -- a clinical lesson

Chordomas usually arise in bone and are most commonly found in the midline axial skeleton. An accurate pre-operative diagnosis of chordoma is crucial, as survival is optimal when radical en bloc resection is performed at primary surgery. We report a rare case of cervical chordoma masquerading radiologically as an extracranial nerve sheath tumour. A laterally situated chordoma (centred extra-osseously in the neural foramen) was diagnosed radiologically as a neurofibroma pre-operatively. We review the key radiological features for diagnosis of chordoma. We consider the importance of pre-operative diagnosis of chordoma in guiding management and in determining survival.

Phylogeography and environmental diversification of a highly adaptable marine amphipod, Gammarus duebeni

Genetic diversity and phylogeographic population structure in the gammarid amphipod, Gammarus duebeni, were investigated across its broad latitudinal distribution in the NE and NW Atlantic by analysis of mitochondrial DNA sequence. Gammarus duebeni has exceptional tolerance of salinity change and inhabits environments ranging from marine to freshwater. The longstanding debate on whether there are distinct marine and freshwater subspecies was assessed by sampling populations from sites characterized by different salinities. Our sequence data demonstrates that there are two major lineages, with little internal geographic structuring. Evidence is provided to suggest a pre-glacial divergence of these two clades, involving segregation between a region historically associated with the freshwater form and the majority of the marine localities on both sides of the Atlantic. A modern contact zone between the marine and freshwater forms is proposed in western Britain.

Falling necropsy rates and risks to public health

Perspective on the paper by Verity et al (see page 608)

Fibre reinforced composite dental bridge. Part I: Experimental investigation

This experimental investigation aims at revealing the mechanical behaviour and failure pattern of direct fibre-reinforced resin-bonded dental bridge with various designs. To evaluate the overall effects of some newly developed dental materials, in the experiment, genuine composite dental bridge specimens are prepared and tested. The ultimate load, stiffness and mode at the failure of the bridges are measured and compared with the design variations. A good agreement between test and some clinical observations is demonstrated. It is verified that the weakest region appears across the pontic-abutment interface in the composite bridges. This study suggests that the composite bridges reinforced by fibres and supported by adjacent teeth could be of a higher structural strength and stiffness; therefore would provide better clinical performances.

Fibre reinforced composite dental bridge. Part II: numerical investigation

Motivated by the clinical success and limitations on experimental investigation of the fibre-reinforced composite dental bridge, this paper aims at providing a numerical investigation into the bridge structure. The finite element (FE) model adopted here is constructed from computer tomography images of a physical bridge specimen. The stress and strain distributions in the bridge structure especially in the bonding interfaces are analyzed in detail. The peak stresses and their variations with the different bridge designs are evaluated. Due to the lower bond strengths of adhesives and the high stress concentration in the pontic-abutment interface, the likelihood of failure in the interface is predicted by finite element analysis. The validity of the numerical results is established by a good agreement between the FE prediction and the tests in the load-deflection responses, the structural stiffness as well as the failure location of the composite dental bridge.

Temozolomide in malignant gliomas of childhood: a United Kingdom Children's Cancer Study Group and French Society for Pediatric Oncology Intergroup Study

PURPOSE

To determine the response rate of the malignant gliomas of childhood to an oral, daily schedule of temozolomide.

PATIENTS AND METHODS

A multicenter, phase II evaluation of an oral, daily schedule of temozolomide (200 mg/m(2) on 5 consecutive days) was undertaken in children with relapsed or progressive, biopsy-proven, high-grade glioma (arm A) and progressive, diffuse, intrinsic brainstem glioma (arm B). Evidence of activity was defined by radiologic evidence of a sustained reduction in tumor size on serial magnetic resonance imaging scans.

RESULTS

Fifty-five patients were recruited (34 to arm A and 21 to arm B) and received 215 cycles of chemotherapy. Grade 3/4 thrombocytopenia was the most frequent toxic event (7% of cycles). Prolonged myelosuppression resulted in significant treatment delays and dose reductions (17% and 22% of cycles, respectively). Two toxic deaths were documented and were related to myelosuppression and sepsis in one patient and pneumonia in a second. The overall (best) response rate was 12% for arm A (95% confidence interval [CI], 3 to 28 in the study cohort, and 2 to 31 for eligible patients) and 5% and 6%, respectively, for arm B (95% CI, 0 to 26 in the study cohort, and 0 to 27 for eligible patients). Stabilization of disease was also documented and was most noteworthy for brainstem gliomas, where two patients achieved both radiologic static disease and discontinued steroid medication.

CONCLUSION

Despite moderate toxicity, objective response rates to temozolomide have been low, indicating that temozolomide has minimal activity in the high-grade gliomas of childhood.

Ultrastructural analysis of the florid plaque in variant Creutzfeldt-Jakob disease

We report here the first description of florid plaques--the hallmark of variant Creutzfeldt-Jakob disease (vCJD). These plaques are composed of broad bundles of amyloid, are highly neuritic and exhibited astrocytes and microglial cells. Collectively, they are more similar to neuritic plaques of Alzheimer's disease than to kuru plaques of kuru--Creutzfeldt-Jakob disease--Gerstmann-Sträussler-Sheinker disease.

Preliminary studies on the optimum shape of dental bridges

Several pre-existing anterior and posterior dental bridge models using Finite elements and the new ceramic material In-Ceram have been developed. The mechanical behaviour of these models has been compared with optimised profiles obtained from a newly developed evolutionary algorithm known as Evolutionary Structural Optimisation (ESO). The results show that the mechanical behaviour of the bridges was mainly restricted by the properties of the porcelain veneer and the design of the bridges themselves. For the case of the anterior bridge, it was found that there existed a specific thickness of veneer that minimised the maximum principal stress. This was related to peak stresses that occurred at the bridge surface. Peak stresses also occurred in the material interface between the In-Ceram and the veneer. These extreme stresses were attributed to the notch size and shape. For the case of the posterior bridge, it was concluded that the shape of the bottom of the Pontic tooth is crucial in reducing the magnitude of the maximum principal tensile stress. The ESO process produced bridge designs which have uniformly stressed bridge surfaces, and which also have significantly lower maximum principal tensile stresses compared to the pre-existing designs (up to 44%).

Adaptation of the bovine spongiform encephalopathy agent to primates and comparison with Creutzfeldt-- Jakob disease: implications for human health

There is substantial scientific evidence to support the notion that bovine spongiform encephalopathy (BSE) has contaminated human beings, causing variant Creutzfeldt-Jakob disease (vCJD). This disease has raised concerns about the possibility of an iatrogenic secondary transmission to humans, because the biological properties of the primate-adapted BSE agent are unknown. We show that (i) BSE can be transmitted from primate to primate by intravenous route in 25 months, and (ii) an iatrogenic transmission of vCJD to humans could be readily recognized pathologically, whether it occurs by the central or peripheral route. Strain typing in mice demonstrates that the BSE agent adapts to macaques in the same way as it does to humans and confirms that the BSE agent is responsible for vCJD not only in the United Kingdom but also in France. The agent responsible for French iatrogenic growth hormone-linked CJD taken as a control is very different from vCJD but is similar to that found in one case of sporadic CJD and one sheep scrapie isolate. These data will be key in identifying the origin of human cases of prion disease, including accidental vCJD transmission, and could provide bases for vCJD risk assessment.

A neuropsychological-neuropathological case study of variant Creutzfeldt-Jakob disease

We report the first neuropsychological-neuropathological case study of a patient with variant Creutzfeldt-Jakob disease (vCJD) who was seen at the early stages of the disease, and whose cognitive functioning was monitored in the following months until his death. At presentation, his neuropsychological profile included impaired ability to retain new episodic information, deficits on tests of retrieval from semantic memory, and impairments on tests of memory for public knowledge, such as famous personalities. Tests of executive function were also performed poorly. Picture recognition memory and autobiographical memory were relatively spared, as was performance on tests of face perception and complex copying ability. Neuropsychological testing may be useful in monitoring the progression of vCJD, and we provide evidence to show a steady rate of decline in perceptual and naming tasks over a 4-month period. Post-mortem findings showed neuronal loss in the caudate, putamen, dorsal thalamus, cerebellum and occipital cortex. Spongiform changes were found throughout the brain, including the entorhinal cortex and anterior thalamus. Prion protein accumulation was noted in the hippocampus. We hypothesize that primary subcortical damage to structures in the thalamus and neostriatum, together with secondary frontal lobe dysfunction, combine to yield the pattern of neuropsychological impairment and neuropsychological sparing that was found.

a controlled trial of intratumoral ONYX-015, a selectively-replicating adenovirus, in combination with cisplatin and 5-fluorouracil in patients with recurrent head and neck cancer

ONYX-015 is an adenovirus with the E1B 55-kDa gene deleted, engineered to selectively replicate in and lyse p53-deficient cancer cells while sparing normal cells. Although ONYX-015 and chemotherapy have demonstrated anti-tumoral activity in patients with recurrent head and neck cancer, disease recurs rapidly with either therapy alone. We undertook a phase II trial of a combination of intratumoral ONYX-015 injection with cisplatin and 5-fluorouracil in patients with recurrent squamous cell cancer of the head and neck. There were substantial objective responses, including a high proportion of complete responses. By 6 months, none of the responding tumors had progressed, whereas all non-injected tumors treated with chemotherapy alone had progressed. The toxic effects that occurred were acceptable. Tumor biopsies obtained after treatment showed tumor-selective viral replication and necrosis induction.

Reversion of prion protein conformational changes by synthetic beta-sheet breaker peptides

BACKGROUND

Transmissible spongiform encephalopathies are associated with a structural transition in the prion protein that results in the conversion of the physiological PrPc to pathological PrP(Sc). We investigated whether this conformational transition can be inhibited and reversed by peptides homologous to the PrP fragments implicated in the abnormal folding, which contain specific residues acting as beta-sheet blockers (beta-sheet breaker peptides).

METHODS

We studied the effect of a 13-residue beta-sheet breaker peptide (iPrP13) on the reversion of the abnormal structure and properties of PrP(Sc) purified from the brains of mice with experimental scrapie and from human beings affected by sporadic and variant Creutzfeldt-Jakob disease. In a cellular model of familial prion disease, we studied the effect of the peptide in the production of the abnormal form of PrP in intact cells. The influence of the peptide on prion infectivity was studied in vivo by incubation time assays in mice with experimental scrapie.

FINDINGS

The beta-sheet breaker peptide partly reversed in-vitro PrP(Sc) to a biochemical and structural state similar to that of PrPc. The effect of the peptide was also detected in intact cells. Treatment of prion infectious material with iPrP13 delayed the appearance of clinical symptoms and decreased infectivity by 90-95% in mice with experimental scrapie.

INTERPRETATION

Beta-sheet breaker peptides reverse PrP conformational changes implicated in the pathogenesis of spongiform encephalopathies. These peptides or their derivatives provide a useful tool to study the role of PrP conformation and might represent a novel therapeutic approach for prion-related disorders.

Compelling transgenetic evidence for transmission of bovine spongiform encephalopathy prions to humans

There is growing concern that bovine spongiform encephalopathy (BSE) may have passed from cattle to humans. We report here that transgenic (Tg) mice expressing bovine (Bo) prion protein (PrP) serially propagate BSE prions and that there is no species barrier for transmission from cattle to Tg(BoPrP) mice. These same mice were also highly susceptible to a new variant of Creutzfeldt-Jakob disease (nvCJD) and natural sheep scrapie. The incubation times (approximately 250 days), neuropathology, and disease-causing PrP isoforms in Tg(BoPrP)Prnp(0/0) mice inoculated with nvCJD and BSE brain extracts were indistinguishable and differed dramatically from those seen in these mice injected with natural scrapie prions. Our findings provide the most compelling evidence to date that prions from cattle with BSE have infected humans and caused fatal neurodegeneration.

A single amino acid alteration (101L) introduced into murine PrP dramatically alters incubation time of transmissible spongiform encephalopathy

A mutation equivalent to P102L in the human PrP gene, associated with Gerstmann-Straussler syndrome (GSS), has been introduced into the murine PrP gene by gene targeting. Mice homozygous for this mutation (101LL) showed no spontaneous transmissible spongiform encephalopathy (TSE) disease, but had incubation times dramatically different from wild-type mice following inoculation with different TSE sources. Inoculation with GSS produced disease in 101LL mice in 288 days. Disease was transmitted from these mice to both wild-type (226 days) and 101LL mice (148 days). In contrast, 101LL mice infected with ME7 had prolonged incubation times (338 days) compared with wild-type mice (161 days). The 101L mutation does not, therefore, produce any spontaneous genetic disease in mice but significantly alters the incubation time of TSE infection. Additionally, a rapid TSE transmission was demonstrated despite extremely low levels of disease-associated PrP.

Ki-67 immunolabelling index is a prognostic indicator in childhood posterior fossa ependymomas

Conventional histological evaluation and subclassification of childhood ependymomas poorly predict their biological behaviour. The Ki-67 labelling index (Ki-67 LI), a measure of growth fraction, correlates with the biological behaviour of several neoplasms, and this retrospective study tested the hypothesis that Ki-67 LI is a prognostic indicator in childhood posterior fossa ependymomas. Immunocytochemistry using an antibody to Ki-67 was undertaken on 5 microns sections of formalin-fixed, paraffin-embedded tissue from 74 cases of childhood (age < 16 years.) posterior fossa ependymoma. A Ki-67 LI was established by counting the proportion of labelled nuclei in more than 1000 cells from several histological fields. Several clinical and histological variables (including Ki-67 LI) potentially associated with survival were entered into univariate and multivariate analyses using a Cox proportional hazards model. Variables that showed a significant and independent association with survival were Ki-67 LI (P < 0.002), whether total surgical resection had been achieved according to operation records (P < 0.03), and whether no adjuvant therapy had been given (P < 0.01). Age, sex, and the presence of necrosis or microvascular proliferation did not correlate with survival. In our defined population of patients with ependymomas, Ki-67 LI is a strong prognostic indicator. We recommend that Ki-67 LI is used in the histological evaluation of childhood posterior fossa ependymomas during trials of novel adjunctive therapies.

Phenotypic variability of Gerstmann-Sträussler-Scheinker disease is associated with prion protein heterogeneity

Gerstmann-Sträussler-Scheinker disease (GSS), a cerebello-pyramidal syndrome associated with dementia and caused by mutations in the prion protein gene (PRNP), is phenotypically heterogeneous. The molecular mechanisms responsible for such heterogeneity are unknown. Since we hypothesize that prion protein (PrP) heterogeneity may be associated with clinico-pathologic heterogeneity, the aim of this study was to analyze PrP in several GSS variants. Among the pathologic phenotypes of GSS, we recognize those without and with marked spongiform degeneration. In the latter (i.e. a subset of GSS P102L patients) we observed 3 major proteinase-K resistant PrP (PrPres) isoforms of ca. 21-30 kDa, similar to those seen in Creutzfeldt-Jakob disease. In contrast, the 21-30 kDa isoforms were not prominent in GSS variants without spongiform changes, including GSS A117V, GSS D202N, GSS Q212P, GSS Q217R, and 2 cases of GSS P102L. This suggests that spongiform changes in GSS are related to the presence of high levels of these distinct 21-30 kDa isoforms. Variable amounts of smaller, distinct PrPres isoforms of ca. 7-15 kDa were seen in all GSS variants. This suggests that GSS is characterized by the presence PrP isoforms that can be partially cleaved to low molecular weight PrPres peptides.

Molecular assessment of the potential transmissibilities of BSE and scrapie to humans

More than a million cattle infected with bovine spongiform encephalopathy (BSE) may have entered the human food chain. Fears that BSE might transmit to man were raised when atypical cases of Creutzfeldt-Jakob disease (CJD), a human transmissible spongiform encephalopathy (TSE), emerged in the UK. In BSE and other TSE diseases, the conversion of the protease-sensitive host prion protein (PrP-sen) to a protease-resistant isoform (PrP-res) is an important event in pathogenesis. Biological aspects of TSE diseases are reflected in the specificities of in vitro PrP conversion reactions. Here we show that there is a correlation between in vitro conversion efficiencies and known transmissibilities of BSE, sheep scrapie and CJD. On this basis, we used an in vitro system to gauge the potential transmissibility of scrapie and BSE to humans. We found limited conversion of human PrP-sen to PrP-res driven by PrP-res associated with both scrapie (PrP[Sc]) and BSE (PrP[BSE]). The efficiencies of these heterologous conversion reactions were similar but much lower than those of relevant homologous conversions. Thus the inherent ability of these infectious agents of BSE and scrapie to affect humans following equivalent exposure may be finite but similarly low.

Molecular analysis of prion strain variation and the aetiology of 'new variant' CJD

Strains of transmissible spongiform encephalopathies are distinguished by differing physicochemical properties of PrPSc, the disease-related isoform of prion protein, which can be maintained on transmission to transgenic mice. 'New variant' Creutzfeldt-Jakob disease (CJD) has strain characteristics distinct from other types of CJD and which resemble those of BSE transmitted to mice, domestic cat and macaque, consistent with BSE being the source of this new disease. Strain characteristics revealed here suggest that the prion protein may itself encode disease phenotype.

Metachronous lymphoma of the breast and conjunctiva

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Squamous cell carcinoma of the eyelid and the acquired immunodeficiency syndrome

PURPOSE

We studied a case of squamous cell carcinoma of the eyelid in a 42-year-old homosexual man with the acquired immunodeficiency syndrome (AIDS) to explore the link between squamous cell carcinoma and human Papillomavirus infection.

METHOD

A rapidly growing, 3-mm lesion was removed from the right lower eyelid by excisional biopsy.

RESULTS

Examination of the lesion confirmed squamous cell carcinoma. Polymerase chain reaction for human Papillomavirus 16 was positive.

CONCLUSION

This case suggests a role for human Papillomavirus infection in the cause of squamous cell carcinoma in AIDS patients.

Intracerebral distribution of infectious amyloid protein in spongiform encephalopathy

We studied the regional distribution of infectious amyloid protein by western immunoblots of brain tissue extracts from 37 patients with different forms of spongiform encephalopathy, i.e., 16 sporadic cases, 18 familial cases with a variety of mutations, and 3 iatrogenic cases. In sporadic and familial Creutzfeldt-Jakob disease, amyloid protein concentrations were usually highest in the frontotemporal regions of the cerebral cortex, whereas iatrogenic Creutzfeldt-Jakob disease and Gerstmann-Sträussler-Scheinker syndrome had as high or higher concentrations in the deep cerebral nuclei and cerebellum. As a group, familial cases had lower amyloid protein concentrations than either sporadic or iatrogenic cases, and fatal familial insomnia patients had the lowest concentrations found in any form of disease. This hierarchy of amyloid protein concentrations corresponds to the experimental transmission rates observed for each form of disease and is consistent with the concept that the protein molecule is an integral component of the infectious agent. Regional amyloid protein pattern analysis of brain and spinal cord may help to distinguish sporadic from environmentally acquired infections, as for example, cases of human disease suspected to have arisen from exposure to sheep or cows infected with scrapie or bovine spongiform encephalopathy.

A case of Creutzfeldt-Jakob disease presenting with cortical deafness

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Progressive paraparesis, lymphocytic meningitis, and stroke in a 37-year-old man

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Stereotaxic brain biopsy in AIDS patients: does it contribute to patient management?

The authors analysed all cases of brain biopsy done in AIDS or HIV+patients at the Department of Clinical Neurosciences, Western General Hospital, Edinburgh, during the period 1989-92 to determine the clinical utility of the procedure. Thirteen lesions were biopsied revealing toxoplasmosis in five, lymphoma in four, progressive multifocal leucoencephalopathy in three, HIV encephalitis in two and encephalitis of unknown aetiology in one. One biopsy specimen contained abnormal tissue but was non-diagnostic. The median survival after biopsy was only 7 weeks, but preoperative immunological (median CD4 count 45) and clinical status of the patients were poor. Although the impact of tissue diagnosis on patient survival was minimal it did enable modification of drug therapy. The authors preliminary experience with biopsy in AIDS patients suggests that the diagnostic information obtained is of limited value in prolonging the lives of patients in poor immunological status, but may be useful in refining medical therapies for toxoplasmosis and progressive multifocal leucoencephalopathy. Whether biopsy should be performed earlier in the course of cerebral disease in an effort to prolong survival time remains unclear.

Teaching image-guided stereotactic methodology and functional neuroanatomy of the thalamus and pallidum: a simple ex vivo technique

A simple and cheap model that enables on site, ex vivo, but very practical, learning of frame-based image-guided stereotactic technique and methodology, and the functional anatomy of the pallidum and thalamus is described. Using a cadaver skull, a specially prepared, formalin-fixed cadaver brain, and a modified stereotactic probe application of a stereotactic frame to the cranium, fiducial point acquisition, target point acquisition, computation of both arc and probe depth settings, and verification of target point accuracy can all be practiced. If diencephalic targets are selected for targeting with ball bearings then section of the cadaver brains, and study of a human thalamic stereotactic atlas provides an excellent and clinically relevant method of learning functionally important thalamic and pallidal anatomy. The method and techniques are described for CT imaging using the Brown-Roberts-Wells frame, but they are equally applicable to other frame types.