Locus co-occupancy, nucleosome positioning, and H3K4me1 regulate the functionality of FOXA2-, HNF4A-, and PDX1-bound loci in islets and liver.

The liver and pancreas share a common origin and coexpress several transcription factors. To gain insight into the transcriptional networks regulating the function of these tissues, we globally identify binding sites for FOXA2 in adult mouse islets and liver, PDX1 in islets, and HNF4A in liver. Because most eukaryotic transcription factors bind thousands of loci, many of which are thought to be inactive, methods that can discriminate functionally active binding events are essential for the interpretation of genome-wide transcription factor binding data. To develop such a method, we also generated genome-wide H3K4me1 and H3K4me3 localization data in these tissues. By analyzing our binding and histone methylation data in combination with comprehensive gene expression data, we show that H3K4me1 enrichment profiles discriminate transcription factor occupied loci into three classes: those that are functionally active, those that are poised for activation, and those that reflect pioneer-like transcription factor activity. Furthermore, we demonstrate that the regulated presence of H3K4me1-marked nucleosomes at transcription factor occupied promoters and enhancers controls their activity, implicating both tissue-specific transcription factor binding and nucleosome remodeling complex recruitment in determining tissue-specific gene expression. Finally, we apply these approaches to generate novel insights into how FOXA2, PDX1, and HNF4A cooperate to drive islet- and liver-specific gene expression.

Citation classics in pediatric orthopaedics.

BACKGROUND: The purpose of this study was to identify the clinical pediatric orthopaedic articles with at least 100 citations published in all orthopaedic journals and to examine their characteristics. METHODS: All journals dedicated to orthopaedics and its subspecialties were selected from the Journal Citation Report 2001 under the subject category "orthopedics." Articles cited 100 times or more were identified using the database of the Science Citation Index Expanded (SCI-EXPANDED, 1900 to present). The articles were ranked in a comprehensive list. Two authors independently reviewed the full text of each article and applied the inclusion and exclusion criteria to the list of articles. The 2 lists were then compared. All disagreements were resolved by consensus with input from the senior author. The final list of pediatric orthopaedic articles was then compiled. RESULTS: There were a total of 49 journals under the search category "orthopedics." Five journals were excluded as they were non-English journals. The remaining 44 journals were screened for articles with at least 100 citations. A total of 135 clinical pediatric orthopaedic articles cited at least 100 times were included. The most cited article was cited 692 times. The mean number of citations per article was 159 (95% confidence interval, 145-173). All the articles were published between 1949 and 2001, with 1980 and 1989 producing the most citation classics (34). The majority (90) originated from the United States, followed by the United Kingdom (12) and Canada (11). Scoliosis/kyphosis was the most common topic with 26 papers. The second most common subject was hip disorders (24). Therapeutic studies were the most common study type (71). Ninety-seven papers were assigned a 4 for level of evidence. CONCLUSIONS: The list of citation classics in pediatric orthopaedic articles is useful for several reasons. It identifies important contributions to the field of pediatric orthopaedics and their originators; it facilitates the understanding and discourse of modern pediatric orthopaedic history and reveals trends in pediatric orthopaedics.

Twenty-year prevalence of diabetes mellitus and hypertension in patients receiving shock-wave lithotripsy for urolithiasis.

OBJECTIVES: To compare the prevalence of hypertension and diabetes mellitus (DM) in patients treated with an unmodified HM-3 lithotripter (USWL) and a second-generation modified HM-3 lithotripter (MSWL) 20 years ago at our Centre with that in the provincial population. To determine whether the type of lithotripter was differentially associated with the development of these sequelae. PATIENTS AND METHODS: Retrospective review of 727 patients at Vancouver General Hospital who underwent shock-wave lithotripsy (SWL) between 1985 and 1989. Our study group was compared with Statistics Canada data describing the provincial prevalence of these diseases. Multivariate analysis was performed. RESULTS: The response rate was 37.3%. There was a greater proportion of overweight and obese individuals in the study group compared with the provincial average. In univariate analysis, lithotripsy with an unmodified HM-3 (USWL) was associated with a higher rate of DM than the provincial rate, whereas lithotripsy with the modified HM-3 (MSWL) was not. Hypertension was more prevalent in all lithotripsy subjects. On multivariate analysis the type of lithotripter was not associated with the development of either sequela. CONCLUSIONS: No association between lithotripsy and the development of either DM or hypertension in a multivariate analysis Metabolic syndrome may have elevated the prevalence of DM and hypertension observed in our subjects on univariate analysis, which is in keeping with the fact that our study population had statistically higher body mass indices than the provincial rate. Lithotripsy using the HM-3 was not associated with increased DM or hypertension.

Expression of Groucho/TLE proteins during pancreas development.

BACKGROUND: The full-length mammalian homologs of groucho, Tle1, 2, 3, and 4, act as transcriptional corepressors and are recruited by transcription factors containing an eh1 or WRPW/Y domain. Many transcription factors critical to pancreas development contain a Gro/TLE interaction domain and several have been shown to require Gro/TLE interactions for proper function during neuronal development. However, a detailed analysis of the expression patterns of the Gro/TLE proteins in pancreas development has not been performed. Moreover, little is known about the ability of Gro/TLE proteins to interact with transcription factors in the pancreas. RESULTS: We describe the expression of Gro/TLE family members, and of 34 different transcription factors that contain a Gro/TLE interaction motif, in the pancreas utilizing nine SAGE libraries created from the developing and adult pancreas, as well as the GenePaint database. Next, we show the dynamic expression of Tle1, 2, 3, 4, 5 and 6 during pancreas development by qRT-PCR. To further define the cell-type specificity of the expression of these proteins we use immunofluorescence to co-localize them with Pdx1 at embryonic day 12.5 (E12.5), Ngn3 at E14.5, Pdx1, Nkx2-2, Insulin, Glucagon, Pancreatic polypeptide and Somatostatin at E18.5, as well as Insulin and Glucagon in the adult. We then show that Tle2 can interact with Nkx2-2, Hes1, Arx, and Nkx6-1 which are all critical factors in pancreas development. Finally, we demonstrate that Tle2 modulates the repressive abilities of Arx in a beta-cell line. CONCLUSION: Although Tle1, 2, 3, and 4 show overlapping expression in pancreatic progenitors and in the adult islet, the expression of these factors is restricted to different cell types during endocrine cell maturation. Of note, Tle2 and Tle3 are co-expressed with Gro/TLE interaction domain containing transcription factors that are essential for endocrine pancreas development. We further demonstrate that Tle2 can interact with several of these factors and that Tle2 modulate Arx's repressive activity. Taken together our studies suggest that Gro/TLE proteins play a role in the repression of target genes during endocrine cell specification.

A multicenter comparison of the safety and effectiveness of ureteroscopic laser lithotripsy in obese and normal weight patients.

OBJECTIVE: Surgical treatment of kidney stones in an obese patient (body mass index [BMI] >30 kg/m(2)) remains challenging as shockwave lithotripsy may not be an option due to weight limitations. We sought to determine the effectiveness of ureteroscopic laser lithotripsy in obese patients compared to nonobese controls. MATERIALS AND METHODS: Patients from 2004 to 2007 were retrospectively analyzed providing a group of 292 patients (163 obese, 76 overweight, 53 normal) who underwent ureteroscopic procedures for urolithiasis at four centers in the United States and Canada. RESULTS: The percentage of obese patients requiring flexible ureteroscopy (URS) (79%) was higher than in the other groups (P<0.0001). Flexible URS was associated with a lower stone-free rate (SFR) on multivariate analysis (P=0.034). There was no difference in SFRs of patients who required a ureteral access sheath, basket extraction, or received a postoperative stent. Complication rates did not differ between groups. CONCLUSION: SFRs using ureteroscopic lithotripsy in obese and overweight populations are the same as in the normal weight patients. A flexible ureteroscope was associated with a decreased SFR, but this likely due to a more proximal stone location in these patients. Ureteroscopic laser lithotripsy is an effective and safe technique to treat urolithiasis in the overweight/obese patient.

Identification of transcripts with enriched expression in the developing and adult pancreas.

BACKGROUND: Despite recent advances, the transcriptional hierarchy driving pancreas organogenesis remains largely unknown, in part due to the paucity of comprehensive analyses. To address this deficit we generated ten SAGE libraries from the developing murine pancreas spanning Theiler stages 17-26, making use of available Pdx1 enhanced green fluorescent protein (EGFP) and Neurog3 EGFP reporter strains, as well as tissue from adult islets and ducts. RESULTS: We used a specificity metric to identify 2,536 tags with pancreas-enriched expression compared to 195 other mouse SAGE libraries. We subsequently grouped co-expressed transcripts with differential expression during pancreas development using K-means clustering. We validated the clusters first using quantitative real time PCR and then by analyzing the Theiler stage 22 pancreas in situ hybridization staining patterns of over 600 of the identified genes using the GenePaint database. These were then categorized into one of the five expression domains within the developing pancreas. Based on these results we identified a cascade of transcriptional regulators expressed in the endocrine pancreas lineage and, from this, we developed a predictive regulatory network describing beta-cell development. CONCLUSION: Taken together, this work provides evidence that the SAGE libraries generated here are a valuable resource for continuing to elucidate the molecular mechanisms regulating pancreas development. Furthermore, our studies provide a comprehensive analysis of pancreas development, and insights into the regulatory networks driving this process are revealed.