Comparative analysis of patient scatter to phantom scatter for computed tomography systems.

Current computed tomography (CT) shielding practices are largely based on calculations of scattered radiation emitted from an acrylic head or body phantom, such as the Computed Tomography Dose Index (CTDI) phantom, or anthropomorphic phantoms of these two anatomical categories. This report considers the difference in scattered air kerma or dose from phantom models, to actual patient scatter under a variety of clinical scan conditions. Empirical patient scatter measurements recorded at different positions around the gantry, for 3 different CT scanners, resulted in average patient scatter fractions per unit Dose Length Product (DLP: mGy cm) at 1 m from the isocentre of 0.09 ± 0.03 and 0.17 ± 0.04 µGy (mGy cm)-1 for head and body scans respectively. For the purposes of shielding design and scattered dose estimates to staff it is recommended that a single standard deviation be applied to these averages in the continued interest of conservatism. These values are reasonably comparative to the widely published scatter fractions by the National Council of Radiological Protection using the CTDI phantom, and the British Institute of Radiology using head and body anthropomorphic phantoms.

Accuracy of genotype imputation in Labrador Retrievers.

The dog is a valuable model species for the genetic analysis of complex traits, and the use of genotype imputation in dogs will be an important tool for future studies. It is of particular interest to analyse the effect of factors like single nucleotide polymorphism (SNP) density of genotyping arrays and relatedness between dogs on imputation accuracy due to the acknowledged genetic and pedigree structure of dog breeds. In this study, we simulated different genotyping strategies based on data from 1179 Labrador Retriever dogs. The study involved 5826 SNPs on chromosome 1 representing the high density (HighD) array; the low-density (LowD) array was simulated by masking different proportions of SNPs on the HighD array. The correlations between true and imputed genotypes for a realistic masking level of 87.5% ranged from 0.92 to 0.97, depending on the scenario used. A correlation of 0.92 was found for a likely scenario (10% of dogs genotyped using HighD, 87.5% of HighD SNPs masked in the LowD array), which indicates that genotype imputation in Labrador Retrievers can be a valuable tool to reduce experimental costs while increasing sample size. Furthermore, we show that genotype imputation can be performed successfully even without pedigree information and with low relatedness between dogs in the reference and validation sets. Based on these results, the impact of genotype imputation was evaluated in a genome-wide association analysis and genomic prediction in Labrador Retrievers.

Prostate cancer in BRCA2 germline mutation carriers is associated with poorer prognosis.

BACKGROUND: The germline BRCA2 mutation is associated with increased prostate cancer (PrCa) risk. We have assessed survival in young PrCa cases with a germline mutation in BRCA2 and investigated loss of heterozygosity at BRCA2 in their tumours. METHODS: Two cohorts were compared: one was a group with young-onset PrCa, tested for germline BRCA2 mutations (6 of 263 cases had a germline BRAC2 mutation), and the second was a validation set consisting of a clinical set from Manchester of known BRCA2 mutuation carriers (15 cases) with PrCa. Survival data were compared with a control series of patients in a single clinic as determined by Kaplan-Meier estimates. Loss of heterozygosity was tested for in the DNA of tumour tissue of the young-onset group by typing four microsatellite markers that flanked the BRCA2 gene, followed by sequencing. RESULTS: Median survival of all PrCa cases with a germline BRCA2 mutation was shorter at 4.8 years than was survival in controls at 8.5 years (P=0.002). Loss of heterozygosity was found in the majority of tumours of BRCA2 mutation carriers. Multivariate analysis confirmed that the poorer survival of PrCa in BRCA2 mutation carriers is associated with the germline BRCA2 mutation per se. CONCLUSION: BRCA2 germline mutation is an independent prognostic factor for survival in PrCa. Such patients should not be managed with active surveillance as they have more aggressive disease.

Insulin resistance and inflammation - A further systemic complication of COPD.

Chronic obstructive pulmonary disease (COPD) is associated with a continuous systemic inflammatory response. Furthermore, COPD is associated with an excess risk for cardiovascular disease and type II diabetes. Systemic inflammation in other populations is a factor in atherogenesis and has been associated with insulin resistance. We assessed the association between systemic inflammation and insulin resistance in non-hypoxaemic patients with COPD. Fasting plasma glucose, insulin and inflammatory mediators were measured in 56 patients and 29 healthy subjects. Body mass index (BMI) and height squared fat- and fat-free-mass index were similar between subject groups. Using homeostatic modelling techniques, mean (SD) insulin resistance was greater in the patients, 1.68 (2.58) and 1.13 (2.02) in healthy subjects, p=0.032. Fasting plasma insulin was increased in patients while glucose was similar to that in healthy subjects. Patients had increased circulating inflammatory mediators. Insulin resistance was related to interleukin-6 (IL-6), r=0.276, p=0.039, and tumour necrosis factor alpha soluble receptor I, r=0.351, p=0.008. Both IL-6 and BMI were predictive variables of insulin resistance r(2)=0.288, p<0.05. We demonstrated greater insulin resistance in non-hypoxaemic patients with COPD compared with healthy subjects, which was related to systemic inflammation. This relationship may indicate a contributory factor in the excess risk of cardiovascular disease and type II diabetes in COPD.

Randomised controlled trial of the cost-effectiveness of water-based therapy for lower limb osteoarthritis.

OBJECTIVES: To determine the efficacy of community water-based therapy for the management of lower limb osteoarthritis (OA) in older patients. DESIGN: A pre-experimental matched-control study was used to estimate efficacy of water-based exercise treatment, to check design assumptions and delivery processes. The main study was a randomised controlled trial of the effectiveness of water-based exercise (treatment) compared with usual care (control) in older patients with hip and/or knee OA. The latter was accompanied by an economic evaluation comparing societal costs and consequences of the two treatments. SETTING: Water exercise was delivered in public swimming pools in the UK. Physical function assessments were carried out in established laboratory settings. PARTICIPANTS: 106 patients (93 women, 13 men) over the age of 60 years with confirmed hip and/or knee OA took part in the preliminary study. A similar, but larger, group of 312 patients (196 women, 116 men) took part in the main study, randomised into control (159) and water exercise (153) groups. INTERVENTIONS: Control group patients received usual care with quarterly semi-structured telephone interview follow-up only. The intervention in the main study lasted for 1 year, with a further follow-up period of 6 months. MAIN OUTCOME MEASURES: Pain score on the Western Ontario and McMaster Universities OA index (WOMAC). Additional outcome measures were included to evaluate effects on quality of life, cost-effectiveness and physical function measurements. RESULTS: Short-term efficacy of water exercise in the management of lower limb OA was confirmed, with effect sizes ranging from 0.44 [95% confidence interval (CI) 0.03 to 0.85] on WOMAC pain to 0.76 (95% CI 0.33 to 1.17) on WOMAC physical function. Of 153 patients randomised to treatment, 82 (53.5%) were estimated to have complied satisfactorily with their treatment at the 1-year point. This had declined to 28 (18%) by the end of the 6-month follow-up period, during which support for the intervention had been removed and those wishing to continue exercise had to pay their own costs for maintaining their exercise treatment. High levels of co-morbidity were recorded in both groups. Nearly two thirds of all patients had a significant other illness in addition to their OA. Fifty-four control and 53 exercise patients had hospital inpatient episodes during the study period. Water exercise remained effective in the main study but overall effect size was small, on WOMAC pain at 1 year, a reduction of about 10% in group mean pain score. This had declined, and was non-significant, at 18 months. Mean cost difference estimates showed a saving in the water exercise group of pound123--175 per patient per annum and incremental cost-effectiveness ratios ranged from pound3838 to pound5951 per quality-adjusted life-year (QALY). Net reduction in pain was achieved at a net saving of pound135--175 per patient per annum and the ceiling valuation of pound580--740 per unit of WOMAC pain reduction was favourably low. CONCLUSIONS: Group-based exercise in water over 1 year can produce significant reduction in pain and improvement in physical function in older adults with lower limb OA, and may be a useful adjunct in the management of hip and/or knee OA. The water-exercise programme produced a favourable cost--benefit outcome, using reduction in WOMAC pain as the measure of benefit. Further research is suggested into other similar public health interventions. Investigation is also needed into how general practice can best be supported to facilitate access to participants for research trials in healthcare, as well as an examination of the infrastructure and workforce capacities for physical activity delivery and the potential extent to which healthcare may be supported in this way. More detailed research is required to develop a better understanding of the types of exercise that will work for the different biomechanical subtypes of knee and hip OA and investigation is needed on access and environmental issues for physical activity programmes for older people, from both a provider and a participant perspective, the societal costs of the different approaches to the management of OA and longer term trends in outcome measures (costs and effects).

Processing of radical prostatectomy specimens for correlation of data from histopathological, molecular biological, and radiological studies: a new whole organ technique.

AIMS: To develop a method of processing non-formalin fixed prostate specimens removed at radical prostatectomy to obtain fresh tissue for research and for correlating diagnostic and molecular results with preoperative imaging. METHODS/RESULTS: The method involves a prostate slicing apparatus comprising a tissue slicer with a series of juxtaposed planar stainless steel blades linked to a support, and a cradle adapted to grip the tissue sample and receive the blades. The fresh prostate gland is held in the cradle and the blades are moved through the cradle slits to produce multiple 4 mm slices of the gland in a plane perpendicular to its posterior surface. One of the resulting slices is preserved in RNAlater. The areas comprising tumour and normal glands within this preserved slice can be identified by matching it to the haematoxylin and eosin stained sections of the adjacent slices that are formalin fixed and paraffin wax embedded. Intact RNA can be extracted from the identified tumour and normal glands within the RNAlater preserved slice. Preoperative imaging studies are acquired with the angulation of axial images chosen to be similar to the slicing axis, such that stained sections from the formalin fixed, paraffin wax embedded slices match their counterparts on imaging. CONCLUSIONS: A novel method of sampling fresh prostate removed at radical prostatectomy that allows tissue samples to be used both for diagnosis and molecular analysis is described. This method also allows the integration of preoperative imaging data with histopathological and molecular data obtained from the prostate tissue slices.

Attaining a correct diagnosis of COPD in general practice.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is common. Diagnosis should include objective evidence of airways obstruction and spirometry is recommended in guidelines and the general medical services contract in the UK. We assessed the impact of spirometry in general practice. METHOD: We determined by questionnaire the availability, staff training, use and the interpretation results of spirometry in 72% of general practices in Wales. We reviewed the diagnosis of COPD previously made in two general practices without spirometry. RESULTS: Most practices had a spirometer (82.4%) and used it (85.6%). Confidence in use and interpretation of results varied widely: 58.1% were confident in use and 33.8% confident in interpretation. Spirometry was performed more often if confident in use and interpretation (both P<0.001) and was related to greater training periods (P<0.001). Spirometric confirmation of COPD varied widely (0-100%, median 37%). Of the 125 patients previously diagnosed with COPD 61 had spirometric confirmation, while 25 had reversible obstruction (range 210-800 mls), 34 had normal and 5 had restrictive spirometry. CONCLUSION: Despite incentives to perform spirometry in general practice, lack of adequate training in use and interpretation suggests use is confounded and the diagnosis of COPD is likely to be made on imprecise clinical grounds.

Association between hormonal genetic polymorphisms and early-onset prostate cancer.

We investigated the association between seven polymorphisms in four candidate genes involved in vitamin D and androgen metabolism with early-onset prostate cancer (CaP) risk. The polymorphisms were genotyped in 288 UK males who were diagnosed with CaP at the age of 55 y or younger and up to 700 population-based controls. An additional 50 cases (not selected for age) and 76 controls were also genotyped. Short (< or =22 repeats) AR (CAG)(n) repeats were associated with a significantly reduced risk of early onset CaP (OR 0.68, 95% CI 0.50-0.91) compared with men with long (> 22) repeats. Men homozygous for the leucine variant of SRD5A2 p.89V > L were also found to be at a significantly increased risk of CaP compared with men who were homozygous for the valine allele (OR 1.84, 95% CI 1.15-2.98). No associations were found with the AR (GGC)(n), CYP17 Msp A1 I, VDR Taq I, SRD5A2 (TA)(n) and p.49A >T polymorphisms and CaP risk. These findings suggest that common polymorphisms in the AR and SRD5A2 genes may be associated with early-onset CaP in British men.

ATM polymorphisms as risk factors for prostate cancer development.

The risk of prostate cancer is known to be elevated in carriers of germline mutations in BRCA2, and possibly also in carriers of BRCA1 and CHEK2 mutations. These genes are components of the ATM-dependent DNA damage signalling pathways. To evaluate the hypothesis that variants in ATM itself might be associated with prostate cancer risk, we genotyped five ATM variants in DNA from 637 prostate cancer patients and 445 controls with no family history of cancer. No significant differences in the frequency of the variant alleles at 5557G>A (D1853N), 5558A>T (D1853V), ivs38-8t>c and ivs38-15g>c were found between the cases and controls. The 3161G (P1054R) variant allele was, however, significantly associated with an increased risk of developing prostate cancer (any G vs CC OR 2.13, 95% CI 1.17-3.87, P=0.016). A lymphoblastoid cell line carrying both the 3161G and the 2572C (858L) variant in the homozygote state shows a cell cycle progression profile after exposure to ionising radiation that is significantly different to that seen in cell lines carrying a wild-type ATM gene. These results provide evidence that the presence of common variants in the ATM gene, may confer an altered cellular phenotype, and that the ATM 3161C>G variant might be associated with prostate cancer risk.

Association between leptin receptor gene polymorphisms and early-onset prostate cancer.

OBJECTIVE: To report a case-control study examining the relationship between polymorphisms in the leptin receptor (OBR) gene and the development of young-onset prostate cancer, because epidemiological studies report that prostate cancer risk is associated with animal fat intake, and thus we investigated if this association occurs via this genetic mechanism. PATIENTS, SUBJECTS AND METHODS: The Lys109Arg (OBR1) and Gln223Arg (OBR2) polymorphisms in the coding region of OBR were studied in blood DNA from 271 patients with prostate cancer aged < 56 years at diagnosis and 277 geographically matched control subjects. Cases were collected through the Cancer Research UK/British Prostate Group Familial Prostate Cancer Study. Blood DNA was genotyped using the polymerase chain reaction and a restriction enzyme digest. RESULTS: There was no statistically significant association between the OBR genotype and prostate cancer risk; men homozygous for 109Arg genotype had a slightly increased risk for prostate cancer, with a relative risk (95% confidence interval) of 1.36 (0.65-2.85), and those homozygous for the 223Arg allele had some reduction in prostate cancer risk, at 0.82 (0.58-1.26), but neither was statistically significant. CONCLUSION: This case-control study showed no significant association between leptin receptor gene polymorphisms and the risk of young-onset prostate cancer, suggesting that genetic variations in OBR are unlikely to have a major role in the development of early-onset prostate cancer in the UK.

Germline mutations in fumarate hydratase (FH) do not predispose to prostate cancer.

Inherited susceptibility to prostate cancer has been linked to a number of chromosomal regions, however no genes have been unequivocally shown to underlie reported linkages. The putative gene localised to chromosome 1q42-q43, has been designated PCaP. We have recently shown that germline mutations in the fumarate hydratase (FH) gene located on 1q43 cause smooth muscle tumours and renal cell carcinoma. It is conceivable that germline FH mutations might confer an increased risk of prostate cancer and underlie linkage of prostate cancer to PCaP. To examine this proposition we have analysed the entire coding region of FH in 160 prostate cancer cases in 77 multiple case families. No pathogenic mutations in FH were identified in any of the cases. This data makes it highly unlikely that mutations in FH confer susceptibility to prostate cancer.

Association between the GCG polymorphism of the selenium dependent GPX1 gene and the risk of young onset prostate cancer.

Epidemiological studies have suggested an association between low selenium levels and the development of prostate cancer. Human cellular glutathione peroxidase I (hGPX1) is a selenium-dependent enzyme that protects against oxidative damage and its peroxidase activity is a plausible mechanism for cancer prevention by selenium. The GPX1 gene has a GCG repeat polymorphism in exon 1, coding for a polyalanine tract of five to seven alanine residues. To test if the GPX1 GCG repeat polymorphism associates with the risk of young-onset prostate cancer we conducted a case-control study. The GPX1Ala genotypes were determined for 267 prostate cancer cases and 260 control individuals using polymerase chain reaction (PCR) amplification with fluorescently labelled primers and an ABI 377 automated genotyper. Associations between specific genotypes and the risk of prostate cancer were examined by logistic regression. We found no significant association between the GPX1 genotypes and prostate cancer. There was however an increased frequency of the GPX1Ala6/Ala6 genotype in the prostate cancer cases compared to controls (OR: 1.67; 95% CI: 0.97-2.87). The result of this study suggests that the GPX1 genotype is unlikely to be associated with the risk of developing prostate cancer.

HPC2/ELAC2 polymorphisms and prostate cancer risk: analysis by age of onset of disease.

The candidate prostate cancer susceptibility gene HPC2/ELAC2 has two common coding polymorphisms: (Ser-->Leu 217) and (Ala-->Thr 541). The Thr541 variant in the HPC2/ELAC2 gene has previously been reported to be at an increased frequency in prostate cancer cases. To evaluate this hypothesis we genotyped 432 prostate cancer patients (including 262 patients diagnosed 55 years (OR=1.27, 95% CI 0.59-2.74). We conclude that any association between the Thr541 variant and prostate cancer is likely to be weak.

No germline mutations in CDKN2A (p16) in patients with squamous cell cancer of the head and neck and second primary tumours.

There is increasing evidence that predisposition to some cancers has a genetic component. There is a high incidence of loss of heterozygosity on chromosome 9, in the region of tumour suppressor gene, CDKN2A (also known as p16), in sporadic squamous cell cancer of the head and neck (SCCHN). To investigate the possibility that CDKN2A may be involved in the inherited susceptibility to SCCHN, the 3 coding exons of CDKN2A were sequenced in 40 patients who had developed a second primary cancer after an index squamous cell cancer of the head and neck. No mutations were found and we conclude that CDKN2A mutations do not play a major role in cancer susceptibility in this group.

Relationship between glutathione S-transferase M1, P1 and T1 polymorphisms and early onset prostate cancer.

There is evidence suggesting that polymorphic variations in the glutathione S-transferases (GSTs) are associated with cancer susceptibility. Inter-individual differences in cancer susceptibility may be mediated in part through polymorphic variability in the bioactivation and detoxification of carcinogens. The GSTs have been consistently implicated as cancer susceptibility genes in this context. The GST supergene family includes several loci with well characterized polymorphisms. Approximately 50% of the Caucasian population are homozygous for deletions in GSTM1 and approximately 20% are homozygous for deletions in GSTT1, resulting in conjugation deficiency of mutagenic electrophiles to glutathione. The GSTP1 gene has a polymorphism at codon 105 resulting in an Ile to Val substitution which consequently alters the enzymatic activity of the protein and this has been suggested as a putative high-risk genotype in various cancers. We investigated the relationship between GST polymorphisms and young onset prostate cancer in a case-control study. GSTM1, GSTT1 and GSTP1 genotypes were determined for 275 prostate cancer patients and for 280 geographically matched control subjects. We found no significant difference in the frequency of GSTM1 or GSTT1 null genotypes between cases and controls. GSTP1 genotype was, however, significantly associated with prostate cancer risk: the Ile/Ile homozygotes had the lowest risk and there was a trend in increasing the risk with the number of 105 Val alleles: Ile/Val odds ratio (OR)= 1.30 (95% FCI 0.99-1.69), Val/Val OR = 1.80 (95% FCI 1.11-2.91); Ptrend = 0.026. These results suggest that the GSTP1 polymorphism may be a risk factor for developing young onset prostate cancer. We also found that carrying more than one putative high-risk allele in the carcinogen metabolizing GST family was associated with an elevated risk for early onset prostate cancer (OR 2.48, 95% FCI 1.22-5.04, Ptrend = 0.017).

An improved high throughput heteroduplex mutation detection system for screening BRCA2 mutations-fluorescent mutation detection (F-MD).

We describe an improved, fast, automated method for screening large genes such as BRCA2 for germline genomic mutations. The method is based on heteroduplex analysis, and has been adapted for a high throughput application by combining the fluorescent technology of automated sequencers and robotic sample handling. This novel approach allows the entire BRCA2 gene to be screened with appropriate overlaps in four lanes of an ABI 377 gel. The method will detect all types of mutations, especially point mutations, more reliably and robustly than other commonly used conformational sensitive methods (e.g. CSGE). In addition we show that this approach, which relies on band shift detection, is able to detect single base substitutions that have hitherto only been detectable by direct sequencing methods.