Effective implementation of the Human Tissue Act.
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Ethics, Research↗
Biomedical subjects
James Ironside
Publications and source records attributed to James Ironside.
Analysis of patients with supratentorial primitive neuro-ectodermal tumours entered into the SIOP/UKCCSG PNET 3 study.
The SIOP PNET 3 study was designed to determine whether 10 weeks of moderately intensive chemotherapy given after surgery and before radiotherapy (RT) would improve the outcome for patients with primitive neuroectodermal tumours (PNETs) compared with RT alone. Patients with a histological diagnosis of supratentorial PNET (StPNET) and no radiological evidence of metastatic disease were initially eligible for randomisation to either chemotherapy followed by craniospinal RT 35 Gy in 21 fractions with a boost of 20 Gy in 12 fractions to the primary site, or RT alone. In respect of the increasing recognition that StPNET were high-risk tumours, randomisation for this group closed in November 1999. This analysis includes both randomised and non-randomised patients with StPNET entered into the study database. Sixty-eight patients aged 2.9-16.6 years (median 6.5 years) were included in the analysis (chemotherapy+RT: 44, RT alone: 24). Fifty-four patients (79%) had a non-pineal and 14 (21%) a pineal site. At a median follow-up of 7.4 years, for all patients overall survival (OS) at 3 and 5 years was 54.4% and 48.3%, respectively. Event-free survival (EFS) at 3 and 5 years was 50.0% and 47.0%, respectively. There was no statistically significant difference in OS or EFS according to treatment received. OS (P=0.05) and EFS (P=0.03) were significantly better for patients with pineal primary sites. EFS for pineal tumours were 92.9% at 3 years and 71.4% at 5 years and for non-pineal primaries 40.7% at 3 years and 40.7% at 5 years. This study confirmed the relatively good survival for non-metastatic pineal PNETs but poor survival of non-pineal StPNETs. There was no evidence that pre-radiation chemotherapy improved outlook. Future treatment programs should be directed at the particular natural history of these tumours, to further define prognostic factors and to explore further biological characteristics.
Adolescent↗
Pre-symptomatic detection of prions by cyclic amplification of protein misfolding.
Transmissible spongiform encephalopathies (TSEs) are neurodegenerative disorders affecting humans and animals. At present, it is not possible to recognize individuals incubating the disease before the clinical symptoms appear. We investigated the effectiveness of the "Protein Misfolding Cyclic Amplification" (PMCA) technology to detect the protease-resistance disease-associated prion protein (PrP(res)) in pre-symptomatic stages. PMCA allowed detection of PrP(res) in the brain of pre-symptomatic hamsters, enabling a clear identification of infected animals as early as two weeks after inoculation. Furthermore, PMCA was able to amplify minute quantities of PrP(res) from a variety of experimental and natural TSEs. Finally, PMCA allowed the demonstration of PrP(res) in an experimentally infected cow 32 month post-inoculation, that did not show clinical signs and was negative by standard Western blot analysis. Our findings indicate that PMCA may be useful for the development of an ultra-sensitive diagnostic test to minimize the risk of further propagation of TSEs.
Animals↗
Outcome for patients with metastatic (M2-3) medulloblastoma treated with SIOP/UKCCSG PNET-3 chemotherapy.
The aim of this study was to determine the outcome for patients with Chang stage M2-3 medulloblastoma (MB) treated with surgery and pre-radiotherapy (RT) chemotherapy (CT). Between 1992 and 2000, 68 patients aged 2.8-16.4 years (median 7.8 years) with M2-3 MB were treated with CT comprising vincristine, etoposide, carboplatin and cyclophosphamide. For 61 patients, CT was followed by craniospinal RT 35 Gy/21 fractions with a posterior fossa (PF) boost, 20 Gy/12 fractions. Twenty-four (35%) irradiated patients received a metastatic boost (mean dose to metastases 47.4 Gy, range 40.0-55.1 Gy). With 7.2-years of median follow-up, overall survival (OS) rates at 3 and 5 years were 50.0% (95% Confidence Interval (CI): 38.1-61.9%) and 43.9% (95% CI: 32.0-55.7%), respectively, event-free survival (EFS) rates at 3 and 5 years were 39.7% (95% CI: 28.1-51.3%) and 34.7% (95% CI: 23.2-46.2%), respectively. Univariate analysis did not demonstrate an impact of age, gender, M stage, extent of resection, RT duration or metastatic boost. For patients commencing RT within 110 days of surgery, EFS was significantly (P=0.04) worse than for those who commenced RT later than this. Response to pre-RT CT was assessable from institutional reports for 44 (65%) patients, and 17 (39%) had a complete response (CR), 15 (34%) a partial response (PR), 4 (9%) stable disease (SD) and 8 (18%) progression. Although CT improved outcome for M0-1 patients in the primitive neuroectodermal tumour (PNET-3) randomised study, and resulted in a high response rate in this study, there has been no apparent improvement in outcome for M2-3 patients when compared with earlier multi-institutional series. Newer approaches such as more intensive CT and RT need to be explored.
Adolescent↗
Variation in concentration of prion protein in the peripheral blood of patients with variant and sporadic Creutzfeldt-Jakob disease detected by dissociation enhanced lanthanide fluoroimmunoassay and flow cytometry.
BACKGROUND: A highly sensitive dissociation-enhanced lanthanide fluoroimmunoassay (DELFIA) and flow cytometry techniques have previously been developed and employed to characterize soluble cellular prion protein (PrP(c)) expression in whole blood and separated components from healthy adult blood donors. No previous studies with these techniques have evaluated the concentration and expression of PrP in the blood of patients with variant Creutzfeldt-Jakob disease (vCJD). STUDY DESIGN AND METHODS: For blood from vCJD patients, sporadic CJD (sCJD) patients, non-CJD neurological controls, and healthy adults, PrP(c) was measured by DELFIA and cell-associated PrP was measured by flow cytometry. RESULTS: DELFIA analysis identified a significant reduction in the concentration of PrP(c) in the whole blood of vCJD (p = 0.012) and non-CJD neurological patients (p = 0.0004) compared with healthy adults. A significant elevation was found in plasma PrP(c) in sCJD patients compared with healthy adult (p = 0.022) and neurological controls (p = 0.050). Flow cytometry found no significant differences between groups in expression of PrP on platelets and lymphocytes, nor in sensitivity of cellular PrP to proteinase K. Neurological controls show significantly less PrP on red cells than healthy adults. CONCLUSION: There are differences in free and cell-associated PrP found in blood of CJD patients and control groups, some of which might be useful with other tests in disease profiling as an aid to diagnoses.
Adult↗
Biochemical fingerprints of prion diseases: scrapie prion protein in human prion diseases that share prion genotype and type.
The phenotype of human prion diseases is influenced by the prion protein (PrP) genotype as determined by the methionine (M)/valine (V) polymorphism at codon 129, the scrapie PrP (PrPSc) type and the etiology. To gain further insight into the mechanisms of phenotype determination, we compared two-dimensional immunoblot profiles of detergent insoluble and proteinase K-resistant PrP species in a type of sporadic Creutzfeldt-Jakob disease (sCJDMM2), variant CJD (vCJD) and sporadic fatal insomnia (sFI). Full-length and truncated PrP forms present in the insoluble fractions were also separately analyzed. These three diseases were selected because they have the same M/M PrP genotype at codon 129 and the same type 2 PrPSc, but different etiologies, also sCJDMM2 and sFI are sporadic, whereas vCJD is acquired by infection. We observed minor differences in the PrP detergent-insoluble fractions between sCJDMM2 and vCJD, although both differ in the corresponding fractions from sFI. We detected more substantial heterogeneity between sCJDMM2 and vCJD in the two-dimensional blots of the proteinase K-resistant PrP fraction suggesting that different PrP species are selected for conversion to proteinase K-resistant PrP in sCJDMM2 and vCJD. These differences are mostly, but not exclusively, due to variations in the type of the N-linked glycans. We also show that the over-representation of the highly glycosylated forms distinctive of the proteinase K-resistant PrPSc of vCJD in one-dimensional blots is due to differences in both the amount and the natures of the glycans. Overall, these findings underline the complexity of phenotypic determination in human prion diseases.
Biomarkers↗
Novel antibody-lectin enzyme-linked immunosorbent assay that distinguishes prion proteins in sporadic and variant cases of Creutzfeldt-Jakob disease.
We used different anti-prion protein (anti-PrP) monoclonal antibodies to capture either full-length or truncated PrP species and then used biotinylated lectin to compare the nature of the glycans on bound PrP species present in control, sporadic Creutzfeldt-Jakob disease (sCJD), or variant CJD (vCJD) brains. When full-length PrP species in these three groups were compared, no significant difference in the binding of concanavalin A or Aleuria aurantia lectin was detected. However, the binding of Ricinus communis agglutinin I (RCA) to sCJD and vCJD samples was significantly increased. In contrast, when only truncated PrP species were compared, only vCJD samples had more RCA binding activity. Therefore, while most of the RCA binding activity in sCJD is restricted to the full-length PrP species, the RCA binding activity in vCJD is associated with truncated and full-length PrP species. Furthermore, the RCA binding activity in sCJD and vCJD samples is mostly associated with proteinase K-resistant PrP species, a known signature of infectious prion. Therefore, PrP species in sCJD and vCJD have dissimilar lectin immunoreactivity, which reflects differences in their N-linked glycans. These differences may account for the distinct phenotypes of sCJD and vCJD.
Biotinylation↗
Motif-grafted antibodies containing the replicative interface of cellular PrP are specific for PrPSc.
Prion diseases are closely associated with the conversion of the cellular prion protein (PrPC) to an abnormal conformer (PrPSc) [Prusiner, S. B. (1998) Proc. Natl. Acad. Sci. USA 95, 13363-13383]. Monoclonal antibodies that bind epitopes comprising residues 96-104 and 133-158 of PrPC potently inhibit this process, presumably by preventing heterodimeric association of PrPC and PrPSc, and suggest that these regions of PrPC may be critical components of the PrPC-PrPSc replicative interface. We reasoned that transplanting PrP sequence corresponding to these regions into a suitable carrier molecule, such as an antibody, could impart specific recognition of disease-associated forms of PrP. To test this hypothesis, polypeptides containing PrP sequence between residues 89-112 or 136-158 were used to replace the extended heavy chain complementarity-determining region 3 of an IgG antibody specific for the envelope glycoprotein of HIV-1. Herein the resulting engineered PrP-IgGs are shown to bind specifically to infective fractions of PrP in mouse, human, and hamster prion-infected tissues, but not to PrPC, other cellular components, or the HIV-1 envelope. PrPSc reactivity was abolished when the sequence of the PrP 89-112 and 136-158 grafts was mutated, scrambled, or N-terminally truncated. Our findings suggest that residues within the 89-112 and 136-158 segments of PrPC are key components of one face of the PrPC-PrPSc complex. PrPSc-specific antibodies produced by the approach described may find widespread application in the study of prion biology and replication and in the detection of infectious prions in human and animal materials.
Amino Acid Sequence↗
Impact of radiotherapy parameters on outcome in the International Society of Paediatric Oncology/United Kingdom Children's Cancer Study Group PNET-3 study of preradiotherapy chemotherapy for M0-M1 medulloblastoma.
PURPOSE: To analyze the impact of radiotherapy (RT) parameters on outcome in a randomized study of pre-RT chemotherapy for M0-M1 medulloblastoma. METHODS AND MATERIALS: Patients were randomized to RT alone or RT preceded by chemotherapy with vincristine, etoposide, carboplatin, and cyclophosphamide. RT consisted of craniospinal RT, 35 Gy in 21 fractions, followed by a posterior fossa (PF) boost of 20 Gy in 12 fractions. The accuracy of cribriform fossa, skull base, and PF field placement was assessed. RESULTS: Between 1992 and 2000, 217 patients were randomized, of whom 179 were eligible for analysis. At a median follow-up of 5.4 years, the 3- and 5-year overall survival rate was 79.5% and 70.7%, respectively. The 3- and 5-year event-free survival (EFS) rate was 71.6% and 67.0%, respectively. EFS was significantly better for the chemotherapy plus RT group (3-year EFS rate 78.5% vs. 64.8%, p = 0.0366). Overall survival and EFS were significantly better for patients completing RT within 50 days compared with those taking >50 days to complete RT (3-year overall survival rate 84.1% vs. 70.9%, p = 0.0356, 3-year EFS rate 78.5% vs. 53.7%, p = 0.0092). Multivariate analysis identified the use of chemotherapy (p = 0.0248) and RT duration (p = 0.0100) as predictive of better EFS. Planning films were reviewed for 131 (74.4%) of 176 patients. Sixty-five (49.6%) had no targeting deviations and 58 (44.3%) had one or more deviations. PF recurrence occurred in 11 (34.4%) of 32 with a PF targeting deviation compared with 13 (16.3%) of 80 without (p = 0.043). No statistically significant impact of other targeting deviations on recurrence risk or EFS were found. CONCLUSION: The results of this study have confirmed the importance of the duration of RT for medulloblastoma. Also, attention to detail when planning RT is important, as illustrated in the case of PF field placement.
Adolescent↗
Quantitative study of spongiform change in putamen of 24 cases of Creutzfeldt-Jakob disease.
Creutzfeldt-Jakob disease (CJD) is characterized by 4 main neuropathological lesions: spongiform change, neuronal loss, astrocytic gliosis, and accumulation of pathological prion protein (PrPsc), which is partially protease-resistant (PrPres). This study focused on spongiform change (SC) in the putamen. Because SC varies from case to case, we investigated whether its quantification could provide relevant criteria to discriminate types of PrPres in CJD. SC was quantified in 24 CJD cases, 12 with PrPres type 1 (CJD-PrP1) and 12 with PrPres type 2 (CJD-PrP2), compared to 25 control cases. The study was performed by direct microscopy examination (DME) and by semiautomatic quantification (SAQ) using shape and size criteria previously described. These criteria were suitable for SC quantification in putamen in the majority of cases, except for those with microspongiosis. The results obtained by DME and SAQ methods were correlated and SC scores were compared to the types of PrPres. Sporadic CJD cases with PrPres type 2 were more affected by SC than type 1, suggesting that putamen could be a preferential site to distinguish type 1 from type 2 histologically. The origin of the difference in SC intensity according to the type of PrPres is discussed in terms of host and strain factors.
Creutzfeldt-Jakob Syndrome↗
Results of a randomized study of preradiation chemotherapy versus radiotherapy alone for nonmetastatic medulloblastoma: The International Society of Paediatric Oncology/United Kingdom Children's Cancer Study Group PNET-3 Study.
PURPOSE: To determine whether preradiotherapy (RT) chemotherapy would improve outcome for Chang stage M0-1 medulloblastoma when compared with RT alone. Chemotherapy comprised vincristine 1.5 mg/m2 weekly for 10 weeks and four cycles of etoposide 100 mg/m2 daily for 3 days, and carboplatin 500 mg/m2 daily for 2 days alternating with cyclophosphamide 1.5 g/m2. PATIENTS AND METHODS: Patients aged 3 to 16 years inclusive were randomly assigned to receive 35 Gy craniospinal RT with a 20 Gy posterior fossa boost, or chemotherapy followed by RT. RESULTS: Of 217 patients randomly assigned to treatment, 179 were eligible for analysis (chemotherapy + RT, 90 patients; RT alone, 89 patients). Median age was 7.67 years, and median follow-up was 5.40 years. Overall survival (OS) at 3 and 5 years was 79.5% and 70.7%, respectively. Event-free survival (EFS) at 3 and 5 years was 71.6% and 67.0%, respectively. EFS was significantly better for chemotherapy and RT (P =.0366), with EFS of 78.5% at 3 years and 74.2% at 5 years compared with 64.8% at 3 years and 59.8% at 5 years for RT alone. There was no statistically significant difference in 3-year and 5-year OS between the two arms (P =.0928). Multivariate analysis identified use of chemotherapy (P =.0248) and time to complete RT (P =.0100) as having significant effect on EFS. CONCLUSION: This is the first large multicenter randomized study to demonstrate improved EFS for chemotherapy compared with RT alone. It is anticipated that this regimen could reduce ototoxicity and nephrotoxicity compared with cisplatin-containing schedules. The importance of avoiding interruptions to RT has been confirmed.
Adolescent↗
Abbreviated incubation times for human prions in mice expressing a chimeric mouse-human prion protein transgene.
Transgenic (Tg) mouse lines that express chimeric mouse-human prion protein (PrP), designated MHu2M, are susceptible to prions from patients with sporadic Creutzfeldt-Jakob disease (sCJD). With the aim of decreasing the incubation time to fewer than 200 days, we constructed transgenes in which one or more of the nine human residues in MHu2M were changed to mouse. The construct with murine residues at positions 165 and 167 was expressed in Tg(MHu2M,M165V,E167Q) mice and resulted in shortening the incubation time to approximately 110 days for prions from sCJD patients. The construct with a murine residue at position 96 resulted in lengthening the incubation time to more than 280 days for sCJD prions. When murine residues 96, 165, and 167 were expressed, the abbreviated incubation times for sCJD prions were abolished. Variant CJD prions showed prolonged incubation times between 300 and 700 days in Tg(MHu2M) mice on first passage and incubation times of approximately 350 days in Tg(MHu2M,M165V,E167Q) mice. On second and third passages of variant CJD prions in Tg(MHu2M) mice, multiple strains of prions were detected based on incubation times and the sizes of the protease-resistant, deglycosylated PrP(Sc) fragments. Our discovery of a previously undescribed chimeric transgene with abbreviated incubation times for sCJD prions should facilitate studies on the prion species barrier and human prion diversity.
Amino Acid Substitution↗
A prion protein epitope selective for the pathologically misfolded conformation.
Conformational conversion of proteins in disease is likely to be accompanied by molecular surface exposure of previously sequestered amino-acid side chains. We found that induction of beta-sheet structures in recombinant prion proteins is associated with increased solvent accessibility of tyrosine. Antibodies directed against the prion protein repeat motif, tyrosine-tyrosine-arginine, recognize the pathological isoform of the prion protein but not the normal cellular isoform, as assessed by immunoprecipitation, plate capture immunoassay and flow cytometry. Antibody binding to the pathological epitope is saturable and specific, and can be created in vitro by partial denaturation of normal brain prion protein. Conformation-selective exposure of Tyr-Tyr-Arg provides a probe for the distribution and structure of pathologically misfolded prion protein, and may lead to new diagnostics and therapeutics for prion diseases.
Amino Acid Motifs↗