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Biomedical subjects

J Young

Publications and source records attributed to J Young.

At least 55 records · Page 3Linked to original sources
PubMed2003

APC mutation and tumour budding in colorectal cancer.

AIM: To determine the frequency of tumour budding and somatic APC mutation in a series of colorectal cancers stratified according to DNA microsatellite instability (MSI) status. MATERIAL/METHODS: Ninety five colorectal cancers were genotyped for APC mutation in the mutation cluster region (exon 15) and scored for the presence of tumour budding at the invasive margin in haematoxylin and eosin stained sections. A subset was immunostained for beta catenin and p16. RESULTS: The frequency of both somatic APC mutation and tumour budding increased pari passu in cancers stratified as sporadic MSI high (MSI-H), hereditary non-polyposis colorectal cancer (HNPCC), MSI low (MSI-L), and microsatellite stable (MSS). Both budding and APC mutation were significantly less frequent in sporadic MSI-H cancers than in MSI-L or MSS cancers. Tumour buds were characterised by increased immunostaining for both beta catenin and p16. CONCLUSION: Tumour budding is associated with an adverse prognosis. The lack of budding in MSI-H colorectal cancer may account for the improved prognosis of this subset and may be explained by an intact WNT signalling pathway and/or inactivated p16(INK4a).

Biomarkers, Tumor↗
PubMed2002

Distinction between familial and sporadic forms of colorectal cancer showing DNA microsatellite instability.

Attempts to classify colorectal cancer into subtypes based upon molecular characterisation are overshadowed by the classical stepwise model in which the adenoma-carcinoma sequence serves as the morphological counterpart. Clarity is achieved when cancers showing DNA microsatellite instability (MSI) are distinguished as sporadic MSI-low (MSI-L), sporadic MSI-high (MSI-H) and hereditary non-polyposis colorectal cancer (HNPCC). Divergence of the 'methylator' pathway into MSI-L and MSI-H is at least partly determined by the respective silencing of MGMT and hMLH1. Multiple differences can be demonstrated between sporadic and familial (HNPCC) MSI-H colorectal cancer with respect to early mechanisms, evolution, molecular characterisation, demographics and morphology. By acknowledging the existence of multiple pathways, rapid advances in the fields of basic and translational research will occur and this will lead to improved strategies for the prevention, early detection and treatment of colorectal cancer.

Base Pair Mismatch↗
PubMed2002

Systematic review of dynamic graciloplasty in the treatment of faecal incontinence.

BACKGROUND: The aim of this systematic review was to compare the safety and efficacy of dynamic graciloplasty with colostomy for the treatment of faecal incontinence. METHODS: Two search strategies were devised to retrieve literature from the Medline, Current Contents, Embase and Cochrane Library databases up until November 1999. Inclusion of papers depended on a predetermined protocol, independent assessments by two reviewers and a final consensus decision. English language papers were selected. Acceptable study designs included randomized controlled trials, controlled clinical trials and case series. Forty papers met the inclusion criteria. They were tabulated and critically appraised in terms of methodology and design, outcomes, and the possible influence of bias, confounding and chance. RESULTS: No high-level evidence was available and there were no comparative studies. Mortality rates were around 2 per cent for both graciloplasty and colostomy. Morbidity rates reported for graciloplasty appear to be higher than those for colostomy. Dynamic graciloplasty was clearly effective at restoring continence in between 42 and 85 per cent of patients, whereas colostomy is, by its design, incapable of restoring continence. However, dynamic graciloplasty is associated with a significant risk of reoperation. CONCLUSION: While dynamic graciloplasty appears to be associated with a higher rate of complications than colostomy, it is clearly a superior intervention for restoring continence in some patients. It is recommended that a comparative, but non-randomized, study be undertaken to evaluate the safety of dynamic graciloplasty in comparison to colostomy, and that the procedure should be performed only in centres where it is carried out routinely.

Anal Canal↗
PubMed2002

Effects of impaired renal function on the pharmacokinetics and toxicity of i.v. ZD9331, a novel non-polyglutamated thymidylate synthase inhibitor, in adult patients with solid tumors.

ZD9331 is a potent thymidylate synthase inhibitor. Renal and hepatic clearances were found to be important routes of elimination. The objectives of this pharmacologic trial were to investigate the effect of renal impairment on the pharmacokinetics of ZD9331, to study the toxicity profile and to document any antitumor effects of ZD9331 when administered i.v. to patients with different degrees of renal impairment. Patients were treated with ZD9331 130 mg/m2 given as an i.v. infusion on day 1 of a 4-week cycle to allow full pharmacokinetic assessment. Subsequent cycles involved the administration of ZD9331 on days 1 and 8, every 3 weeks. Patients were stratified according to their renal function assessed by the creatinine clearance: normal renal function (creatinine clearance > or =60 ml/min), mildly impaired renal function (creatinine clearance > or =40 to <60 ml/min) and moderately impaired renal function (creatinine clearance >25 to <40 ml/min). For pharmacokinetic analysis plasma sampling was performed during the first course and assayed using a validated liquid chromatographic tandem mass spectrometry assay. Twenty-three patients were entered on the study, of whom 21 received 130 mg/m2 ZD9331 in the first treatment cycle. No relationship was seen between renal impairment and plasma clearance nor with the area under the concentration-time curve of free ZD9331. Increasing renal impairment was associated with a greater incidence of myelosuppression. No predictive relationship between the clearance of free ZD9331 and the degree of renal impairment as determined by creatinine clearance could be assessed. However, data from this trial indicate that increased renal impairment may be associated with greater ZD9331-induced toxicity, particularly myelosuppression, although this cannot be attributed to any alteration in the plasma pharmacokinetics of ZD9331. Therefore, it may be necessary to administer a reduced dose of ZD9331 to patients with impaired renal function.

Adult↗
PubMed2002

Elk restoration in Ontario, Canada: infectious disease management strategy, 1998-2001.

Ontario has embarked upon a program to restore elk (Cervus elaphus) that were once native to that province. A comprehensive disease-management strategy has ensured that elk are free of infectious diseases such as brucellosis and tuberculosis prior to shipment to Ontario. Postmortem analysis occurs on elk mortalities in Ontario to ensure that elk are not infected with diseases such as chronic wasting disease and tuberculosis. Between 1998 and 2001, a total of 443 elk were transported from Elk Island National Park, Alberta, and released in four different areas of Ontario. Cumulative mortality for elk in all areas was 26% from 1998 to January 2001. The primary causes of mortality were post-release stress-induced emaciation (21%), wolf predation (20%), transport/handling injuries (10%), bacterial infections (10%), and drowning (7%). Female calves had the highest mortality rates (37%) compared to the other sex and age cohorts (23-24%). Preliminary findings suggest an inverse correlation between the length of time elk are held in enclosures prior to release and the distance they disperse from the release site. The 2001 estimated population of elk in Ontario is about 400 individuals.

Age Factors↗
PubMed2002

A case of myoepithelial carcinoma displaying biallelic inactivation of the tumour suppressor gene APC in a patient with familial adenomatous polyposis.

Familial adenomatous polyposis (FAP) is an autosomal dominant disorder caused by mutation of the APC gene. It is characterised by the appearance of hundreds to thousands of colorectal adenomas in adolescence and the subsequent development of colorectal cancer. Various extracolonic malignancies are associated with FAP, including desmoids and neoplasms of the stomach, duodenum, pancreas, liver, and brain. We present a family affected by FAP with an exon 14 APC mutation displaying two rare extracolonic lesions, a hepatoblastoma and a myoepithelial carcinoma. The hepatoblastoma was found in a male patient aged 2 years. The second lesion, a myoepithelial carcinoma of the right cheek, was found in a female patient aged 14 years. Inactivation of the normal APC allele was demonstrated in this lesion by loss of heterozygosity analysis, thus implicating APC in the initiation or progression of this neoplasm. This is the first reported case of this lesion in a family affected by FAP.

Adenomatous Polyposis Coli↗
PubMed2001

A test-retest reliability study of the Barthel Index, the Rivermead Mobility Index, the Nottingham Extended Activities of Daily Living Scale and the Frenchay Activities Index in stroke patients.

PURPOSE: To assess the test-retest reliability of a range of outcome measures in stroke patients. METHOD: Twenty-two patients > 1 year post-stroke were tested twice at an interval of 1 week using the Barthel Index (BI); the Rivermead Mobility Index (RMI); the Nottingham Extended Activities of Daily Living Scale (NEADL); and the Frenchay Activities Index (FAI). The mean difference (bias) and reliability coefficient (random error) were calculated for the total scores. Percentage agreement and the kappa coefficient were used to analyse individual items. RESULTS: The mean differences and reliability coefficients were BI 0.4 +/- 2.0, RMI 0.3 +/- 2.2, the NEADL 0.6 +/- 5.6, FAI -0.6 +/- 7.1. There was little bias between assessments. The performance of the BI and RMI were better with lower random error. The NEADL and FAI did not perform as well having larger random error components. Percentage agreements were generally high especially for the BI (>75%) and RMI (>85%), but there was considerable variation in the kappa coefficients. CONCLUSION: Measurement of basic activities of daily living and mobility as measured by the BI and RMI is reliable post-stroke. Measurements used to assess extended activities of daily living were less reliable in this study.

Activities of Daily Living↗
PubMed2001

Kirsten ras mutations in patients with colorectal cancer: the 'RASCAL II' study.

Researchers worldwide with information about the Kirsten ras (Ki-ras) tumour genotype and outcome of patients with colorectal cancer were invited to provide that data in a schematized format for inclusion in a collaborative database called RASCAL (The Kirsten ras in-colorectal-cancer collaborative group). Our results from 2721 such patients have been presented previously and for the first time in any common cancer, showed conclusively that different gene mutations have different impacts on outcome, even when the mutations occur at the same site on the genome. To explore the effect of Ki-ras mutations at different stages of colorectal cancer, more patients were recruited to the database, which was reanalysed when information on 4268 patients from 42 centres in 21 countries had been entered. After predetermined exclusion criteria were applied, data on 3439 patients were entered into a multivariate analysis. This found that of the 12 possible mutations on codons 12 and 13 of Kirsten ras, only one mutation on codon 12, glycine to valine, found in 8.6% of all patients, had a statistically significant impact on failure-free survival (P = 0.004, HR 1.3) and overall survival (P = 0.008, HR 1.29). This mutation appeared to have a greater impact on outcome in Dukes' C cancers (failure-free survival, P = 0.008, HR 1.5; overall survival P = 0.02, HR 1.45) than in Dukes' B tumours (failure-free survival, P = 0.46, HR 1.12; overall survival P = 0.36, HR 1.15). Ki-ras mutations may occur early in the development of pre-cancerous adenomas in the colon and rectum. However, this collaborative study suggests that not only is the presence of a codon 12 glycine to valine mutation important for cancer progression but also that it may predispose to more aggressive biological behaviour in patients with advanced colorectal cancer.

Adolescent↗
PubMed2001

Instabilotyping: comprehensive identification of frameshift mutations caused by coding region microsatellite instability.

Coding region frameshift mutation caused by microsatellite instability (MSI) is one mechanism contributing to tumorigenesis in cancers with MSI in high frequency. Mutation of TGFBR2 is one example of this process. To identify additional examples, a large-scale genomic screen of coding region microsatellites was conducted. 1115 coding homopolymeric loci with six or more nucleotides were identified in an online genetic database. Mutational screening was performed at 152 of these loci in 46 colorectal tumors with MSI in high frequency. Nine loci were mutated in > or =20% of tumors, 10 loci in 10-20%, 24 loci in 5-10%, 43 loci in <5%, and 66 loci were not mutated in any tumors. The most frequently mutated novel loci were the activin type II receptor gene (58.1%), SEC63 (48.8%), AIM 2 (47.6%), a gene encoding a subunit of the NADH-ubiquinone oxidoreductase complex (27.9%), a homologue of mouse cordon-bleu (23.8%), and EBP1/PA2G4 (20.9%). This genome-wide approach identifies coding region MSI in genes or pathways not implicated previously in colorectal tumorigenesis, which may merit functional study or other additional analysis.

3' Untranslated Regions↗
PubMed2001

Albuminuria and risk of cardiovascular events, death, and heart failure in diabetic and nondiabetic individuals.

CONTEXT: Microalbuminuria is a risk factor for cardiovascular (CV) events. The relationship between the degree of albuminuria and CV risk is unclear. OBJECTIVES: To estimate the risk of CV events in high-risk individuals with diabetes mellitus (DM) and without DM who have microalbuminuria and to determine whether levels of albuminuria below the microalbuminuria threshold increase CV risk. DESIGN: The Heart Outcomes Prevention Evaluation study, a cohort study conducted between 1994 and 1999 with a median 4.5 years of follow-up. SETTING: Community and academic practices in North and South America and Europe. PARTICIPANTS: Individuals aged 55 years or more with a history of CV disease (n = 5545) or DM and at least 1 CV risk factor (n = 3498) and a baseline urine albumin/creatinine ratio (ACR) measurement. MAIN OUTCOME MEASURES: Cardiovascular events (myocardial infarction, stroke, or CV death); all-cause death; and hospitalization for congestive heart failure. RESULTS: Microalbuminuria was detected in 1140 (32.6%) of those with DM and 823 (14.8%) of those without DM at baseline. Microalbuminuria increased the adjusted relative risk (RR) of major CV events (RR, 1.83; 95% confidence interval [CI], 1.64-2.05), all-cause death (RR, 2.09; 95% CI, 1.84-2.38), and hospitalization for congestive heart failure (RR, 3.23; 95% CI, 2.54-4.10). Similar RRs were seen for participants with or without DM, even after adjusting for other CV risk factors (eg, the adjusted RR of the primary aggregate end point was 1.97 [95% CI, 1.68-2.31] in those with DM and 1.61 [95% CI, 1.36-1.90] in those without DM). Compared with the lowest quartile of ACR (<0.22 mg/mmol), the RRs of the primary aggregate end point in the second quartile (ie, ACR range, 0.22-0.57 mg/mmol) was 1.11 (95% CI, 0.95-1.30); third quartile, 1.38 (95% CI, 1.19-1.60; ACR range, 0.58-1.62 mg/mmol); and fourth quartile, 1.97 (95% CI, 1.73-2.25; ACR range, >1.62 mg/mmol) (P for trend <.001, even after excluding those with microalbuminuria). For every 0.4-mg/mmol increase in ACR level, the adjusted hazard of major CV events increased by 5.9% (95% CI, 4.9%-7.0%). CONCLUSIONS: Our results indicate that any degree of albuminuria is a risk factor for CV events in individuals with or without DM; the risk increases with the ACR, starting well below the microalbuminuria cutoff. Screening for albuminuria identifies people at high risk for CV events.

Aged↗
PubMed2001

Genomic analysis of orthologous mouse and human olfactory receptor loci.

Olfactory receptor (OR) genes represent approximately 1% of genomic coding sequence in mammals, and these genes are clustered on multiple chromosomes in both the mouse and human genomes. We have taken a comparative genomics approach to identify features that may be involved in the dynamic evolution of this gene family and in the transcriptional control that results in a single OR gene expressed per olfactory neuron. We sequenced approximately 350 kb of the murine P2 OR cluster and used synteny, gene linkage, and phylogenetic analysis to identify and sequence approximately 111 kb of an orthologous cluster in the human genome. In total, 18 mouse and 8 human OR genes were identified, including 7 orthologs that appear to be functional in both species. Noncoding homology is evident between orthologs and generally is confined within the transcriptional unit. We find no evidence for common regulatory features shared among paralogs, and promoter regions generally do not contain strong promoter motifs. We discuss these observations, as well as OR clustering, in the context of evolutionary expansion and transcriptional regulation of OR repertoires.

5' Untranslated Regions↗
PubMed2001

Evidence databases, the Internet, and general practitioners: the New Zealand story.

AIM: To determine self-reported access to and use of the Internet and the Cochrane Library by general practitioners (GPs) in New Zealand. METHODS: A national cross sectional postal and fax survey of randomly selected GPs. RESULTS: A total of 381 of 459 eligible GPs returned completed questionnaires (83%). The mean age of this sample was 45.7 years (SD 8.6) and average years in general practice was 15.7 years (SD 8.8 years). 74% (277) were male and 77% (289) in full-time practice. Internet access was present in 40% (95% CI 36-46%) of practices and 76% (72-81%) of GP's homes. The majority, 56% (51-61%), of GPs had used the Internet with regard to a patient. Younger GPs (<35 years old OR = 2.69, 95% CI 1.10-6.60) and male GPs (OR 1.72, 95% CI 1.02-2.90) were significantly more likely to report use of the Internet with respect to patients. 42% (95% CI 37-47%) of GPs were aware of the Cochrane Library but only 15% (11-19%) had used it. Those in group practice were more likely to be aware of the Cochrane database (adjusted OR 1.85, CI 1.09-3.12). CONCLUSIONS: Internet use is prevalent among GPs. Solo practitioners, older GPs and female GPs are least likely to avail themselves of this resource. Although half of GPs knew about Cochrane, a minority used it. Access and use of evidence databases can be improved in New Zealand. Strategies to assist those least likely already to use Cochrane may help our collective efforts towards evidence based practice.

Adult↗