Predicting perioperative mortality after oesophagectomy: a systematic review of performance and methods of multivariate models.

Predicting risk of perioperative mortality after oesophagectomy for cancer may assist patients to make treatment choices and allow balanced comparison of providers. The aim of this systematic review of multivariate prediction models is to report their performance in new patients, and compare study methods against current recommendations. We used PRISMA guidelines and searched Medline, Embase, and standard texts from 1990 to 2012. Inclusion criteria were English language articles reporting development and validation of prediction models of perioperative mortality after open oesophagectomy. Two reviewers screened articles and extracted data for methods, results, and potential biases. We identified 11 development, 10 external validation, and two clinical impact studies. Overestimation of predicted mortality was common (5-200% error), discrimination was poor to moderate (area under receiver operator curves ranged from 0.58 to 0.78), and reporting of potential bias was poor. There were potentially important case mix differences between modelling and validation samples, and sample sizes were considerably smaller than is currently recommended. Steyerberg and colleagues' model used the most 'transportable' predictors and was validated in the largest sample. Most models have not been adequately validated and reported performance has been unsatisfactory. There is a need to clarify definition, effect size, and selection of currently available candidate predictors for inclusion in prediction models, and to identify new ones strongly associated with outcome. Adoption of prediction models into practice requires further development and validation in well-designed large sample prospective studies.

Biallelic DICER1 mutations occur in Wilms tumours.

DICER1 is an endoribonuclease central to the generation of microRNAs (miRNAs) and short interfering RNAs (siRNAs). Germline mutations in DICER1 have been associated with a pleiotropic tumour predisposition syndrome and Wilms tumour (WT) is a rare manifestation of this syndrome. Three WTs, each in a child with a deleterious germline DICER1 mutation, were screened for somatic DICER1 mutations and were found to bear specific mutations in either the RNase IIIa (n = 1) or the RNase IIIb domain (n = 2). In the two latter cases, we demonstrate that the germline and somatic DICER1 mutations were in trans, suggesting that the two-hit hypothesis of tumour formation applies for these examples of WT. Among 191 apparently sporadic WTs, we identified five different missense or deletion somatic DICER1 mutations (2.6%) in four individual WTs; one tumour had two very likely deleterious somatic mutations in trans in the RNase IIIb domain (c.5438A>G and c.5452G>A). In vitro studies of two somatic single-base substitutions (c.5429A>G and c.5438A>G) demonstrated exon 25 skipping from the transcript, a phenomenon not previously reported in DICER1. Further we show that DICER1 transcripts lacking exon 25 can be translated in vitro. This study has demonstrated that a subset of WTs exhibits two 'hits' in DICER1, suggesting that these mutations could be key events in the pathogenesis of these tumours.

Constitutional relaxation of insulin-like growth factor II gene imprinting associated with Wilms' tumour and gigantism.

We have examined the imprinting of the insulin-like growth factor II gene (IGF2) in ten normal kidney samples from children with renal embryonal neoplasms. In kidney samples from nine children with normal growth profiles, IGF2 mRNA was transcribed monoallelically, consistent with normal imprinting of the gene. But in one child who had generalized somatic overgrowth, IGF2 was transcribed from both alleles in her kidney, peripheral blood leukocytes and Wilms' tumour. These findings suggest that a defect in genomic imprinting can occur constitutionally, leading to growth abnormalities and predisposition to Wilms' tumour.

Mutation of the PAX2 gene in a family with optic nerve colobomas, renal anomalies and vesicoureteral reflux.

Paired box (PAX) genes play a critical role in human development and disease. The PAX2 gene is expressed in primitive cells of the kidney, ureter, eye, ear and central nervous system. We have conducted a mutational analysis of PAX2 in a family with optic nerve colobomas, renal hypoplasia, mild proteinuria and vesicoureteral reflux. We report a single nucleotide deletion in exon five, causing a frame-shift of the PAX2 coding region in the octapeptide domain. The phenotype resulting from the PAX2 mutation in this family was very similar to abnormalities that have been reported in Krd mutant mice. These data suggest that PAX2 is required for normal kidney and eye development.

Jackson-Weiss and Crouzon syndromes are allelic with mutations in fibroblast growth factor receptor 2.

Jackson-Weiss syndrome is an autosomal dominant condition characterized by craniosynostosis, foot anomalies and great phenotypic variability. Recently mutations in fibroblast growth factor receptor 2 (FGFR2) have been found in patients with another craniosynostotic syndrome, Crouzon syndrome. FGFR2 is a member of the tyrosine kinase receptor superfamily, having a high affinity for peptides that signal the transduction pathways for mitogenesis, cellular differentiation and embryogenesis. We now report an FGFR2 mutation in the conserved region of the immunoglobulin IIIc domain in the Jackson-Weiss syndrome family in which the syndrome was originally described. In addition, in four of 12 Crouzon syndrome cases, we identified two new mutations and found two previously described mutations in the same region.

When and how to update systematic reviews.

BACKGROUND: Systematic reviews are most helpful if they are up-to-date. We did a systematic review of strategies and methods describing when and how to update systematic reviews. OBJECTIVES: To identify, describe and assess strategies and methods addressing: 1) when to update systematic reviews and 2) how to update systematic reviews. SEARCH STRATEGY: We searched MEDLINE (1966 to December 2005), PsycINFO, the Cochrane Methodology Register (Issue 1, 2006), and hand searched the 2005 Cochrane Colloquium proceedings. SELECTION CRITERIA: We included methodology reports, updated systematic reviews, commentaries, editorials, or other short reports describing the development, use, or comparison of strategies and methods for determining the need for updating or updating systematic reviews in healthcare. DATA COLLECTION AND ANALYSIS: We abstracted information from each included report using a 15-item questionnaire. The strategies and methods for updating systematic reviews were assessed and compared descriptively with respect to their usefulness, comprehensiveness, advantages, and disadvantages. MAIN RESULTS: Four updating strategies, one technique, and two statistical methods were identified. Three strategies addressed steps for updating and one strategy presented a model for assessing the need to update. One technique discussed the use of the "entry date" field in bibliographic searching. Statistical methods were cumulative meta-analysis and predicting when meta-analyses are outdated. AUTHORS' CONCLUSIONS: Little research has been conducted on when and how to update systematic reviews and the feasibility and efficiency of the identified approaches is uncertain. These shortcomings should be addressed in future research.

A colony-stimulating factor 1 (CSF-1) receptor/platelet-derived growth factor-beta receptor gene fusion confers CSF-1 independence and tumorigenicity on a c-myc-immortalized monocyte cell line.

Monocytes and macrophages express the receptor for the hematopoietic growth factor colony-stimulating factor 1 (CSF-1) and require this factor for growth in culture. A murine monocyte tumor cell line that lacks the usual requirement for CSF-1 was isolated. On the basis of the similarity of the structures of the CSF-1 and platelet-derived growth factor (PDGF) receptors and because monocytes normally secrete PDGF, we analyzed the tumor cell line for anomalous expression of the PDGF-R beta gene. Two different cDNAs that each contain sequences corresponding to the complete coding sequence of PDGF-R beta fused (in frame) to the amino-terminal half of the CSF-1 receptor were isolated. Introduction of these PDGF-R beta-related cDNAs into two partially transformed, CSF-1-dependent monocyte cell lines resulted in autonomous growth and cell transformation. These monocyte cell lines exhibit a novel form of growth factor receptor activation that can lead to oncogenic growth in collaboration with the c-myc oncogene.

WITHDRAWN: Selective serotonin reuptake inhibitors (SSRIs) versus other antidepressants for depression.

BACKGROUND: The relatively new class of antidepressant, the selective serotonin reputake inhibitors (SSRIs), may be better tolerated than the older tricyclic antidepressants. This review compares the efficacy of SSRIs with other antidepressants. OBJECTIVES: To examine the relative efficacy of selective serotonin reuptake inhibitors (SSRIs) compared to other antidepressants. SEARCH STRATEGY: The search strategy included a search of (a) Electronic bibliographic databases (MEDLINE, EMBASE); (b) reference lists of related reviews (c) reference lists of all located studies (d) contact with the manufacturer and (e) the Cochrane Group register of controlled trials SELECTION CRITERIA: Randomised controlled trials comparing selective serotonin reuptake inhibitors with other kinds of antidepressants in the treatment of patients with depressive disorders. The outcome measures assessed included measures of the severity of depression. DATA COLLECTION AND ANALYSIS: Data were collected from each study the main outcome measurefrom each study. These included: mean Hamilton depression rating scale, mean Montgomery & Asberg depression rating scale, Clinical Global Impression rating scale. An analysis of standardised mean difference of these scales was performed using Review Manager 3.1 software. The presence of heterogeneity of treatment effect was assessed MAIN RESULTS: Ninety-eight trials contributed data to the analysis of the relative efficacy of SSRIs and related drugs with comparator antidepressants (Figure 3 & Appendix 3). Analysis of efficacy was based upon 5044 patients treated with an SSRI or related drug, and 4510 treated with an alternative antidepressant. The standardised effect size for SSRIs and related drugs together versus alternative antidepressants using a fixed effects model was 0.035 (95% CI -0.006 to 0.076; Q = 149.25, df = 97, p < 0.001). AUTHORS' CONCLUSIONS: There are no clinically significant differences in effectiveness between selective serotonin reuptake inhibitors and tricyclic antidepressants. Treatment decisions need to be based on considerations of relative patient acceptability, toxicity and cost.

WITHDRAWN: Treatment discontinuation with selective serotonin reuptake inhibitors (SSRIs) versus tricyclic antidepressants (TCAs).

BACKGROUND: Selective serotonin reuptake inhibitors are thought to have better discontinuation rates (i.e. less people dropping out) than tricyclic and heterocyclic antidepressant drugs. It is important to quantify the drop-out rates of different antidepressant drugs in order to have a better understanding of the relative tolerability of these drugs. OBJECTIVES: To assess the comparative tolerability of selective serotonin reuptake inhibitors and tricyclic/heterocyclic antidepressant drugs. SEARCH STRATEGY: We searched the Cochrane Collaboration Depression, Anxiety and Neurosis Controlled Trials Registers (1997 to 1999), MEDLINE (1966 to 1999), EMBASE (1974 to 1999) We also searched specialist journals, the reference lists of relevant papers and previous systematic reviews, conference abstracts and government documents. Representatives of the pharmaceutical industry were contacted. SELECTION CRITERIA: Parallel group randomised controlled trials comparing selective serotonin reuptake inhibitors with tricyclic or heterocyclic antidepressants in people with depression. DATA COLLECTION AND ANALYSIS: Two reviewers independently extracted data and a third reviewer checked any cases of disagreement. MAIN RESULTS: We included 136 trials. The selective serotonin reuptake inhibitors showed less participants dropping out compared to the tricyclic/heterocyclic group (odds ratio 1.21, 95% confidence interval 1.12 to 1.30). A statistically significant difference was found in total drop-outs between the selective serotonin reuptake inhibitors and the old tricyclics as well as the newer tricyclics. When the selective serotonin reuptake inhibitors were compared to the heterocyclic antidepressants, there was a non significant difference favouring the selective serotonin reuptake inhibitors. The poor tolerability profile of the old tricyclics was explained by differences in drop-outs for side-effects, but not for inefficacy. AUTHORS' CONCLUSIONS: Whilst selective serotonin reuptake inhibitors do appear to show an advantage over tricyclic drugs in terms of total drop-outs, this advantage is relatively modest. This has implications for pharmaco-economic models, some of which may have overestimated the difference of drop-out rates between selective serotonin reuptake inhibitors and tricyclic antidepressants. These results are based on short-term randomised controlled trials, and may not generalise into clinical practice.

An ovine hepatorenal fibrocystic model of a Meckel-like syndrome associated with dysmorphic primary cilia and TMEM67 mutations.

Meckel syndrome (MKS) is an inherited autosomal recessive hepatorenal fibrocystic syndrome, caused by mutations in TMEM67, characterized by occipital encephalocoele, renal cysts, hepatic fibrosis, and polydactyly. Here we describe an ovine model of MKS, with kidney and liver abnormalities, without polydactyly or occipital encephalocoele. Homozygous missense p.(Ile681Asn; Ile687Ser) mutations identified in ovine TMEM67 were pathogenic in zebrafish phenotype rescue assays. Meckelin protein was expressed in affected and unaffected kidney epithelial cells by immunoblotting, and in primary cilia of lamb kidney cyst epithelial cells by immunofluorescence. In contrast to primary cilia of relatively consistent length and morphology in unaffected kidney cells, those of affected cyst-lining cells displayed a range of short and extremely long cilia, as well as abnormal morphologies, such as bulbous regions along the axoneme. Putative cilia fragments were also consistently located within the cyst luminal contents. The abnormal ciliary phenotype was further confirmed in cultured interstitial fibroblasts from affected kidneys. These primary cilia dysmorphologies and length control defects were significantly greater in affected cells compared to unaffected controls. In conclusion, we describe abnormalities involving primary cilia length and morphology in the first reported example of a large animal model of MKS, in which we have identified TMEM67 mutations.

Insulin-like growth factor II and WT1 transcript localization in human fetal kidney and Wilms' tumor.

In situ hybridization was used to examine, in parallel, the localization of insulin-like growth factor II (Igf2) and WT1 transcripts in normal fetal kidney and Wilms' tumor. The expression of Igf2 and WT1 transcripts in the fetal kidney is almost complementary in both the epithelial and stromal cell lineages derived from the undifferentiated metanephrogenic blastema. The patterns of transcription of Igf2 in three Wilms' tumors appeared to be perturbed as compared to the normal fetal kidney. In these tumors Igf2 transcripts were detected in structures that are developmentally equivalent to the renal vesicle, which in the normal kidney do not contain Igf2 transcripts. These results suggest that Wilms' tumors arise from an alteration in the regulation of Igf2 mRNA synthesis.

A third Wilms' tumor locus on chromosome 16q.

Loss of heterozygosity studies have been used to identify chromosomal regions which are frequently deleted and thus indicate areas which may harbor tumor suppressor genes. As a result, both the WT1 gene located in chromosome 11p13 and an unidentified gene(s) within chromosome 11p15 have been implicated in Wilms' tumorigenesis. Cytogenetic and linkage studies suggest that additional non-chromosome 11 sites are involved in Wilms' tumor. Because these sites may also involve loss of heterozygosity, loci on 33 autosomal arms were screened for allele loss in a series of Wilms' tumors. We found that in addition to loss on chromosome 11p (11 of 25 informative tumors) there was significant loss on chromosome 16q (9 of 45 informative tumors), while the total frequency of allele loss excluding these loci was low (9 of 426 total informative loci). These data indicate that losses of both chromosome 11p and 16q alleles are nonrandom events and suggest that 16q is the location of a third tumor suppressor gene underlying Wilms' tumorigenesis. The parental origin of the lost chromosome 16q allele was determined in eight sporadic tumors. Alleles of paternal and of maternal origin were each lost in four sporadic tumors indicating that, unlike chromosome 11p, alleles of either parental origin are lost on 16q.

Examination of the role of CSF-1 independence in myc retrovirus induced monocyte tumorigenesis.

These studies were initiated as an attempt to estimate the number and nature of genetic changes that are required in addition to c-myc deregulation during monocyte tumorigenesis, and to determine whether the oncogenic changes that can be created in vitro resemble the actual changes that occur in vivo. We found that superinfecting myc-immortalized monocytes with a colony stimulating factor-1 (CSF-1) expressing retrovirus strongly promoted tumorigenesis, whereas granulocyte/macrophage-CSF (GM-CSF) and v-fms retroviruses, or the spontaneous acquisition of CSF-1 independence did so only moderately. In addition myc-infected monocytes isolated from mice at a stage prior to tumor formation are more tumorigenic than in vitro myc-immortalized monocytes, but they were still largely CSF-1 dependent, and were not as tumorigenic as reinnoculated tumor cells. In the simplest model only two oncogenic activations are required for monocyte/macrophage transformation, immortalization of the cells with c-myc and deregulation of the CSF-1 gene. However, not all mechanisms that result in loss of CSF-1 dependence lead to full tumorigenicity, suggesting that in vivo tumorigenesis may involve multiple secondary events including growth factor independence.

Cloning of novel Wilms tumor gene (WT1) cDNAs; evidence for antisense transcription of WT1.

WT1 is a tumor suppressor gene that has been implicated in Wilms tumor, and is expressed in cells of mesodermal origin. The Wit-1 gene is located approximately 2 kb from the WT1 gene, and is expressed coordinately with WT1. WT1 and Wit-1 are bi-directionally transcribed from the same promoter region. We have screened a human fetal kidney cDNA library to identify novel WT1 cDNA clones. Here we report the cloning of cDNA clones which span part of intron 1 of WT1, exon 1, upstream sequences between WT1 and Wit-1 and part of the Wit-1 gene. Northern blot and RNAase protection analysis using subcloned fragments of the cDNAs corresponding to regions from within intron 1 of WT1 suggest that a 7-10 Kb RNA is expressed in human fetal kidney, which overlaps with WT1 and is transcribed in the same direction as Wit-1.

Exclusion of the Wilms tumour gene (WT1) promoter as a site of frequent mutation in Wilms tumour.

WT1 is a tumour suppressor gene expressed in a specific temporal and spatial pattern in the developing kidney. Up to 15% of Wilms tumours have point mutations in the WT1 gene coding sequence. We have now investigated whether mutations in the WT1 promoter could be associated with loss of control WT1 expression and subsequent Wilms tumour formation. Using single-strand conformational polymorphism (SSCP) analysis we analysed 39 sporadic Wilms tumours for WT1 promoter mutations. We found six linked common sequence polymorphisms and two unlinked less frequent polymorphisms which allowed us to identify four tumours with loss of heterozygosity but none with point mutations, small deletions, insertions or rearrangements. We therefore conclude that WT1 promoter mutations are unlikely to play an important role in Wilms tumorigenesis.

Differential regulation of the human Wilms tumour suppressor gene (WT1) promoter by two isoforms of PAX2.

PAX2 is a member of the paired box family of genes with an important role in kidney, genital tract and eye development. Another gene essential for kidney and genital tract development is the Wilms tumour gene, WT1. PAX2 and WT1 encode transcription factors expressed during fetal kidney development in patterns that overlap both spatially and temporally. The overlap of PAX2 and WT1 expression in fetal kidney prompted us to determine whether PAX2 regulates the WT1 gene. To investigate this possibility, the WT1 promoter and a series of WT1 promoter deletion fragments were cloned into a luciferase reporter vector, and used in co-transfection experiments with PAX2 expression constructs. PAX2 transactivated the WT1 promoter up to 35-fold in CHO-K1 cells, and from four- to sevenfold in 293 cells. Two regions of the WT1 promoter were required in the same promoter construct for efficient transactivation by PAX2 in CHO-K1 cells, and purified recombinant PAX2 protein was found to bind to two sites in the WT1 promoter, at -205/-230 and +377/+402. Removal of WT1 promoter sequences containing the -205/-230, or +377/+402 binding sites abolished transactivation of the WT1 promoter by PAX2 in CHO-K1 cells, and had a differential effect on transactivation of the WT1 promoter in 293 cells, depending on the PAX2 isoform used. A fragment containing the -205/-230 site alone could be transactivated by PAX2. These findings suggest that PAX2 is a tissue-specific modulator of WT1 expression, and is involved in cell growth control via WT1.

What do we know about how to do audit and feedback? Pitfalls in applying evidence from a systematic review.

BACKGROUND: Improving the quality of health care requires a range of evidence-based activities. Audit and feedback is commonly used as a quality improvement tool in the UK National Health Service [NHS]. We set out to assess whether current guidance and systematic review evidence can sufficiently inform practical decisions about how to use audit and feedback to improve quality of care. METHODS: We selected an important chronic disease encountered in primary care: diabetes mellitus. We identified recommendations from National Institute for Clinical Excellence (NICE) guidance on conducting audit and generated questions which would be relevant to any attempt to operationalise audit and feedback in a healthcare service setting. We explored the extent to which a systematic review of audit and feedback could provide practical guidance about whether audit and feedback should be used to improve quality of diabetes care and, if so, how audit and feedback could be optimised. RESULTS: National guidance suggests the importance of securing the right organisational conditions and processes. Review evidence suggests that audit and feedback can be effective in changing healthcare professional practice. However, the available evidence says relatively little about the detail of how to use audit and feedback most efficiently. CONCLUSION: Audit and feedback will continue to be an unreliable approach to quality improvement until we learn how and when it works best. Conceptualising audit and feedback within a theoretical framework offers a way forward.

PAX2 mutations in renal-coloboma syndrome: mutational hotspot and germline mosaicism.

The renal-coloboma syndrome (RCS, MIM 120330) is an autosomal dominant disorder caused by PAX2 gene mutations. We screened the entire coding sequence of the PAX2 gene for mutations in nine patients with RCS. We found five heterozygous PAX2 gene mutations: a dinucleotide insertion (2G) at position 619 in one sporadic RCS case, a single nucleotide insertion (619 + G) in three unrelated cases, and a single nucleotide deletion in a familial case. In this familial case, three affected sibs showed a striking ocular phenotypic variability. Each of the sibs carried a 619insG mutation, whilst unaffected parents did not, suggesting the presence of germline mosaicism. Interestingly, the 619insG mutation has been previously reported in several patients and is also responsible for the Pax21Neu mouse mutant, an animal model of human RCS. This study confirms the critical role of the PAX2 gene in human renal and ocular development. In addition, it emphasises the high variability of ocular defects associated with PAX2 mutations ranging from subtle optic disc anomalies to microphthalmia. Finally, the presence of PAX2 germline mosaicism highlights the difficulties associated with genetic counselling for PAX2 mutations.

Genes encoding the platelet-derived growth factor (PDGF) receptor and colony-stimulating factor 1 (CSF-1) receptor are physically associated in mice as in humans.

The BALB/c mouse DNA was analyzed by field-inversion gel electrophoresis to determine the orientation and distance between the beta-platelet-derived growth factor receptor-encoding gene (Pdgfr) and the colony-stimulating factor 1 receptor-encoding gene (Csfmr). It was found that the 5' portion of the Pdgfr gene was cleaved by the enzyme ClaI into two fragments. The 425-kb fragment hybridized with a 3' Pdgfr and a 5' Csfmr probe. This result shows that the Csfmr gene is 3' relative to the Pdgfr gene, and suggests that the Pdgfr and Csfmr genes are physically linked.