ABSTRACT: Retinal haemorrhages are an important finding in children with abusive and accidental head trauma. There are no standardised and validated protocols to describe them in a consistent manner. The aim of this web-based study was to establish the reliability and validity of a new retinal haemorrhage description tool.
Our tool is a comprehensive questionnaire, which is applied using a retinal schematic that divides the retina into four independent zones. Four independent observers scored retinal haemorrhages from 80 retinal photographs. Inter- and intra-rater agreement (by repeat assessment of 10 photographs for each examiner) were calculated using Fleiss κ statistics.
A high inter-rater agreement was noted for haemorrhages in the peripapillary zones, whereas agreement was only fair for all other zones. Intra-rater agreement was high only for the posterior pole. Photographs may be an unreliable way of documenting retinal haemorrhages particularly from the peripheral retina, thus underscoring the importance of a thorough clinical examination.
This study shows that the tool achieves some validity for describing haemorrhages in the posterior retina. It performs less well in the peripheral zones.
The British journal of ophthalmology 12/2011; 95(12):1719-22. · 2.92 Impact Factor
ABSTRACT: Normalization in real-time qRT-PCR is necessary to compensate for experimental variation. A popular normalization strategy employs reference gene(s), which may introduce additional variability into normalized expression levels due to innate variation (between tissues, individuals, etc). To minimize this innate variability, multiple reference genes are used. Current methods of selecting reference genes make an assumption of independence in their innate variation. This assumption is not always justified, which may lead to selecting a suboptimal set of reference genes.
We propose a robust approach for selecting optimal subset(s) of reference genes with the smallest variance of the corresponding normalizing factors. The normalizing factor variance estimates are based on the estimated unstructured covariance matrix of all available candidate reference genes, adjusting for all possible correlations. Robustness is achieved through bootstrapping all candidate reference gene data and obtaining the bootstrap upper confidence limits for the variances of the log-transformed normalizing factors. The selection of the reference gene subset is optimized with respect to one of the following criteria: (A) to minimize the variability of the normalizing factor; (B) to minimize the number of reference genes with acceptable upper limit on variability of the normalizing factor, (C) to minimize the average rank of the variance of the normalizing factor. The proposed approach evaluates all gene subsets of various sizes rather than ranking individual reference genes by their stability, as in the previous work. In two publicly available data sets and one new data set, our approach identified subset(s) of reference genes with smaller empirical variance of the normalizing factor than in subsets identified using previously published methods. A small simulation study indicated an advantage of the proposed approach in terms of sensitivity to identify the true optimal reference subset in the presence of even modest, especially negative correlation among the candidate reference genes.
The proposed approach performs comprehensive and robust evaluation of the variability of normalizing factors based on all possible subsets of candidate reference genes. The results of this evaluation provide flexibility to choose from important criteria for selecting the optimal subset(s) of reference genes, unless one subset meets all the criteria. This approach identifies gene subset(s) with smaller variability of normalizing factors than current standard approaches, particularly if there is some nontrivial innate correlation among the candidate genes.
BMC Bioinformatics 01/2010; 11:253. · 2.75 Impact Factor
ABSTRACT: Pancreatic ductal adenocarcinoma is an aggressive disease. Surgical resection with negative margins (R0) offers the only opportunity for cure. Patients who have advanced disease that limits the chance for R0 surgical resection may undergo margin positive (MP) pancreaticoduodenectomy (PD), palliative surgical bypass (PB), celiac plexus neurolysis alone (PX), or neoadjuvant chemoradiation therapy in anticipation of future resection.
The aim of this study was to determine if there is a difference in the perioperative outcomes and survival patterns between patients who undergo MP PD and those who undergo PB for locally advanced disease in the treatment of pancreatic ductal adenocarcinoma.
We reviewed our pancreatic surgery database (January 2005-December 2007) to identify all patients who underwent exploration with curative intent of pancreatic ductal adenocarcinoma of the head/neck/uncinate process of the pancreas. Four groups of patients were identified, R0 PD, MP PD, PB, and PX.
We identified 126 patients who underwent PD, PB, or PX. Fifty-six patients underwent R0 PD, 37 patients underwent MP PD, 24 patients underwent a PB procedure, and nine patients underwent PX. In the PB group, 58% underwent gastrojejunostomy (GJ) plus hepaticojejunostomy (HJ), 38% underwent GJ alone, and 4% underwent HJ alone. Of these PB patients, 25% had locally advanced disease and 75% had metastatic disease. All nine patients in the PX group had metastatic disease. The mean age, gender distribution, and preoperative comorbidities were similar between the groups. For the MP PD group, the distribution of positive margins on permanent section was 57% retroperitoneal soft tissue, 19% with more than one positive margin, 11% pancreatic neck, and 8% bile duct. The perioperative complication rates for the respective groups were R0 36%, MP 49%, PB 33%, and PX 22%. The 30-day perioperative mortality rate for the entire cohort was 2%, with all three of these deaths being in the R0 group. The median follow-up for the entire cohort was 14.4 months. Median survival for the respective groups was R0 27.2 months, MP 15.6 months, PB 6.5 months, and PX 5.4 months.
Margin positive pancreaticoduodenectomy in highly selected patients can be performed safely, with low perioperative morbidity and mortality. Further investigation to determine the role of adjuvant treatment and longer-term follow-up are required to assess the durability of survival outcomes for patients undergoing MP PD resection.
Journal of Gastrointestinal Surgery 09/2009; 13(11):1937-46; discussion 1946-7. · 2.83 Impact Factor