Multidimensional outlook on the pathophysiology of cervical cancer invasion and metastasis

Cervical cancer being one of the primary causes of high mortality rates among women is an area of concern, especially with ineffective treatment strategies. Extensive studies are carried out to understand various aspects of cervical cancer initiation, development and progression; however, invasive cervical squamous cell carcinoma has poor outcomes. Moreover, the advanced stages of cervical cancer may involve lymphatic circulation with a high risk of tumor recurrence at distant metastatic sites. Dysregulation of the cervical microbiome by human papillomavirus (HPV) together with immune response modulation and the occurrence of novel mutations that trigger genomic instability causes malignant transformation at the cervix. In this review, we focus on the major risk factors as well as the functionally altered signaling pathways promoting the transformation of cervical intraepithelial neoplasia into invasive squamous cell carcinoma. We further elucidate genetic and epigenetic variations to highlight the complexity of causal factors of cervical cancer as well as the metastatic potential due to the changes in immune response, epigenetic regulation, DNA repair capacity, and cell cycle progression. Our bioinformatics analysis on metastatic and non-metastatic cervical cancer datasets identified various significantly and differentially expressed genes as well as the downregulation of potential tumor suppressor microRNA miR-28-5p. Thus, a comprehensive understanding of the genomic landscape in invasive and metastatic cervical cancer will help in stratifying the patient groups and designing potential therapeutic strategies.

Micro-CT imaging of multiple K-edge elements using GaAs and CdTe photon counting detectors

Objective.To evaluate the performance of two photon-counting (PC) detectors based on different detector materials, gallium arsenide (GaAs) and cadmium telluride (CdTe), for PC micro-CT imaging of phantoms with multiple contrast materials. Another objective is to determine if combining these two detectors in the same micro-CT system can offer higher spectral performance and significant artifact reduction compared to a single detector system.Approach. We have constructed a dual-detector, micro-CT system equipped with two PCDs based on different detector materials: gallium arsenide (GaAs) and cadmium telluride (CdTe). We demonstrate the performance of these detectors for PC micro-CT imaging of phantoms with up to 5 contrast materials with K-edges spread across the x-ray spectrum ranging from iodine with a K-edge at 33.2 keV to bismuth with a K-edge at 90.5 keV. We also demonstrate the use of our system to image a mouse prepared with both iodine and bismuth contrast agents to target different biological systems.Main results.When using the same dose and scan parameters, GaAs shows increased low energy (<50 keV) spectral sensitivity and specificity compared to CdTe. However, GaAs performance at high energies suffers from spectral artifacts and has comparatively low photon counts indicating wasted radiation dose. We demonstrate that combining a GaAs-based and a CdTe-based PC detector in the same micro-CT system offers higher spectral performance and significant artifact reduction compared to a single detector system.Significance.More accurate PC micro-CT using a GaAs PCD alone or in combination with a CdTe PCD could serve for developing new contrast agents such as nanoparticles that show promise in the developing field of theranostics (therapy and diagnostics).

A Recurrent Case of Ameloblastic Fibroma in 37-year Old Male

Ameloblastic fibroma (AF) is a benign mixed epithelial and mesenchymal odontogenic tumor. This was previously grouped in odontogenic tumor showing odontogenic epithelium with odontogenic ectomesenchyme, with or without hard tissue formation. This report describes a case of ameloblastic fibroma in a 37-yearold male who came with the complain of swelling in the left side of lower jaw since one year. Enucleation of the mass followed by reconstruction was done six years back. However, after two years of initial treatment; radiographic findings suggested recurrence. Histopathological examination confirmed the diagnosis of ameloblastic fibroma. Patient had no clinical and radiographic evidence of recurrence in three and six months' follow-up. Because of the higher proliferative capacity and malignant degree of the mesenchymal component in the recurrent neoplasm, sarcomatous transformation may occur. Hence, a long term clinical and radiographical follow-up is essential due to its transformation into ameloblastic fibrosarcoma.

ZNF471 modulates EMT and functions as methylation regulated tumor suppressor with diagnostic and prognostic significance in cervical cancer

Cervical cancer (CC) is a leading cause of cancer-related death among women in developing countries. However, the underlying mechanisms and molecular targets for therapy remain to be fully understood. We investigated the epigenetic regulation, biological functions, and clinical utility of zinc-finger protein 471 (ZNF471) in CC. Analysis of cervical tissues and five independent public datasets of CC showed significant hypermethylation of the ZNF471 gene promoter. In CC cell lines, promoter DNA methylation was inversely correlated with ZNF471 expression. The sensitivity and specificity of the ZNF471 hypermethylation for squamous intraepithelial lesion (SIL) vs tumor and normal vs tumor was above 85% with AUC of 0.937. High methylation and low ZNF471 expression predicted poor overall and recurrence-free survival. We identified -686 to +114 bp as ZNF471 promoter, regulated by methylation using transient transfection and luciferase assays. The promoter CpG site methylation of ZNF471 was significantly different among cancer types and tumor grades. Gal4-based heterologous luciferase reporter gene assays revealed that ZNF471 acts as a transcriptional repressor. The retroviral mediated overexpression of ZNF471 in SiHa and CaSki cells inhibited growth, proliferation, cell migration, invasion; delayed cell cycle progression in vitro by increasing cell doubling time; and reduced tumor growth in vivo in nude mice. ZNF471 overexpression inhibited key members of epithelial-mesenchymal transition (EMT), Wnt, and PI3K-AKT signaling pathways. ZNF471 inhibited EMT by directly targeting vimentin as analyzed by bioinformatic analysis, ChIP-PCR, and western blotting. Thus, ZNF471 CpG specific promoter methylation may determine the prognosis of CC and could function as a potential tumor suppressor by targeting EMT signaling.

Endoscopic Resections in Inflammatory Bowel Disease: A Multicentre European Outcomes Study

BACKGROUND AND AIMS

Inflammatory bowel disease is associated with an increased risk of colorectal cancer, with estimates ranging 2-18%, depending on the duration of colitis. The management of neoplasia in colitis remains controversial. Current guidelines recommend endoscopic resection if the lesion is clearly visible with distinct margins. Colectomy is recommended if complete endoscopic resection is not guaranteed. We aimed to assess the outcomes of all neoplastic endoscopic resections in inflammatory bowel disease.

METHODS

This was a multicentre retrospective cohort study of 119 lesions of visible dysplasia in 93 patients, resected endoscopically in inflammatory bowel disease.

RESULTS

A total of 6/65 [9.2%] lesions <20 mm in size were treated by ESD [endoscopic submucosal dissection] compared with 59/65 [90.8%] lesions <20 mm treated by EMR [endoscopic mucosal resection]; 16/51 [31.4%] lesions >20 mm in size were treated by EMR vs 35/51 [68.6%] by ESD. Almost all patients [97%] without fibrosis were treated by EMR, and patients with fibrosis were treated by ESD [87%], p < 0.001. In all, 49/78 [63%] lesions treated by EMR were resected en-bloc and 27/41 [65.9%] of the ESD/KAR [knife-assisted resection] cases were resected en-bloc, compared with 15/41 [36.6%] resected piecemeal. Seven recurrences occurred in the cohort. Seven complications occurred in the cohort; six were managed endoscopically and one patient with a delayed perforation underwent surgery.

CONCLUSIONS

Larger lesions with fibrosis are best treated by ESD, whereas smaller lesions without fibrosis are best managed by EMR. Both EMR and ESD are feasible in the management of endoscopic resections in colitis.

SEIS: Insight's Seismic Experiment for Internal Structure of Mars

By the end of 2018, 42 years after the landing of the two Viking seismometers on Mars, InSight will deploy onto Mars' surface the SEIS (Seismic Experiment for Internal Structure) instrument; a six-axes seismometer equipped with both a long-period three-axes Very Broad Band (VBB) instrument and a three-axes short-period (SP) instrument. These six sensors will cover a broad range of the seismic bandwidth, from 0.01 Hz to 50 Hz, with possible extension to longer periods. Data will be transmitted in the form of three continuous VBB components at 2 sample per second (sps), an estimation of the short period energy content from the SP at 1 sps and a continuous compound VBB/SP vertical axis at 10 sps. The continuous streams will be augmented by requested event data with sample rates from 20 to 100 sps. SEIS will improve upon the existing resolution of Viking's Mars seismic monitoring by a factor of ∼ 2500 at 1 Hz and ∼ 200 000 at 0.1 Hz. An additional major improvement is that, contrary to Viking, the seismometers will be deployed via a robotic arm directly onto Mars' surface and will be protected against temperature and wind by highly efficient thermal and wind shielding. Based on existing knowledge of Mars, it is reasonable to infer a moment magnitude detection threshold of M w ∼ 3 at 40 ∘ epicentral distance and a potential to detect several tens of quakes and about five impacts per year. In this paper, we first describe the science goals of the experiment and the rationale used to define its requirements. We then provide a detailed description of the hardware, from the sensors to the deployment system and associated performance, including transfer functions of the seismic sensors and temperature sensors. We conclude by describing the experiment ground segment, including data processing services, outreach and education networks and provide a description of the format to be used for future data distribution.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (10.1007/s11214-018-0574-6) contains supplementary material, which is available to authorized users.

Extended Spectrum β-lactamase (ESBL) Producing Multi Drug Resistant (MDR) Urinary Pathogens in a Children Hospital from Nepal

Background Multidrug resistant in clinical bacterial isolates has increasingly been reported through out the world and is associated with high morbidity, mortality and increased health care costs. It is important to determine the status of multidrug resistance pattern to understand the current resistance trend so that appropriate antibiotics can be used in practice. Objective To determine the antibiotic resistant profile and prevalence of extended spectrum β-lactamase producing multidrug resistant strains in pediatric patients of Kanti Children's Hospital, Kathmandu, Nepal. Method Urine sample was cultured by standard microbiological techniques and bacterial isolates were identified using different biochemical tests. Antibiotic susceptibility testing was performed by Kirby Bauer disc diffusion method and extended spectrum β-lactamase detection was carried out using combined disc method as recommended by Clinical Laboratory Standard Institute guidelines. Result All together 65 different bacteria were isolated and subsequently identified. E. coli was the most common isolate with 46 (71%) isolates 63% of these isolates were multidrug resistant. Gram negative isolates were most resistant to nalidixic acid (81.97%) followed by ampicillin (69.35%) and co-trimoxazole (69.35%). The extended spectrum β-lactamase producing isolates were 43% among total isolates. Conclusion Higher rate of Extended Spectrum β-lactamase production among multidrug resistant isolates suggested routine extended spectrum β-lactamase testing in clinical isolates.

The safety and efficacy of radiofrequency ablation following endoscopic submucosal dissection for Barrett's neoplasia

The current standard of treating early Barrett's neoplasia is resection of visible lesions using endoscopic mucosal resection (EMR) followed by ablative therapy to the Barrett's segment. There is increasing evidence to support the use of endoscopic submucosal dissection (ESD) where en-bloc resection and lower recurrence rates may be achieved. However, ESD is associated with deep submucosal dissection when compared to EMR. This may increase the risk of complications including stricture formation with subsequent radiofrequency ablation (RFA) therapy. The aim of this study is to compare the safety and efficacy of RFA following EMR and ESD as well as when RFA was used without prior endoscopic resection. The primary outcome measure was complication rates. Clearance of dysplasia (CRD) and clearance of intestinal metaplasia (CRIM) were secondary outcomes. A retrospective analysis of a cohort of 91 patients referred for RFA from a single academic tertiary center was performed. The choice of endoscopic resection method was tailored according to the lesion type and morphology. Focal and circumferential ablation was performed after initial follow up endoscopy postresection. Patients proceeded straight to RFA in the absence of any visible lesions. In this study, the ESD group had a higher proportion of cancers compared to the EMR cohort (74.1% vs. 30.2%, P < 0.01) prior to RFA. All complications post RFA occurred in the groups with previous endoscopic resection. There was no significant difference in the total complication rate (7.4% vs. 9.3%, P = 0.78) and stricture formation rate (3.7% vs. 9.3%, P = 0.38) between the ESD and EMR groups. CRD was achieved in 96.3% in the ESD group, 88.4% in the EMR group, and all patients in the RFA alone group. CRIM rates were similar in the EMR and ESD groups (81.4% vs. 85.2%) but higher in the RFA alone group (90.5%). In conclusion, RFA following ESD is very effective and not associated with an increased risk of complications compared to EMR. This supports the application of RFA in the treatment algorithm of patients undergoing ESD for Barrett's neoplasia.

Genomewide Association Study of Alcohol Dependence Identifies Risk Loci Altering Ethanol-Response Behaviors in Model Organisms

BACKGROUND

Alcohol dependence (AD) shows evidence for genetic liability, but genes influencing risk remain largely unidentified.

METHODS

We conducted a genomewide association study in 706 related AD cases and 1,748 unscreened population controls from Ireland. We sought replication in 15,496 samples of European descent. We used model organisms (MOs) to assess the role of orthologous genes in ethanol (EtOH)-response behaviors. We tested 1 primate-specific gene for expression differences in case/control postmortem brain tissue.

RESULTS

We detected significant association in COL6A3 and suggestive association in 2 previously implicated loci, KLF12 and RYR3. None of these signals are significant in replication. A suggestive signal in the long noncoding RNA LOC339975 is significant in case:control meta-analysis, but not in a population sample. Knockdown of a COL6A3 ortholog in Caenorhabditis elegans reduced EtOH sensitivity. Col6a3 expression correlated with handling-induced convulsions in mice. Loss of function of the KLF12 ortholog in C. elegans impaired development of acute functional tolerance (AFT). Klf12 expression correlated with locomotor activation following EtOH injection in mice. Loss of function of the RYR3 ortholog reduced EtOH sensitivity in C. elegans and rapid tolerance in Drosophila. The ryanodine receptor antagonist dantrolene reduced motivation to self-administer EtOH in rats. Expression of LOC339975 does not differ between cases and controls but is reduced in carriers of the associated rs11726136 allele in nucleus accumbens (NAc).

CONCLUSIONS

We detect association between AD and COL6A3, KLF12, RYR3, and LOC339975. Despite nonreplication of COL6A3, KLF12, and RYR3 signals, orthologs of these genes influence behavioral response to EtOH in MOs, suggesting potential involvement in human EtOH response and AD liability. The associated LOC339975 allele may influence gene expression in human NAc. Although the functions of long noncoding RNAs are poorly understood, there is mounting evidence implicating these genes in multiple brain functions and disorders.

Colonic lesion characterisation skills among UK endoscopists and the impact of a brief training intervention

OBJECTIVE

To assess UK gastroenterology registrars' and consultants' competence in in vivo characterisation of polyps, plus the impact of a dedicated colonic lesion characterisation training intervention.

DESIGN

Prospective evaluation of a computer-based colonic lesion training module.

SETTING

Three UK general hospitals.

PATIENTS

High-quality endoscopic images obtained during colonoscopy in a previous study.

INTERVENTIONS

30 min computer-based training module covering in vivo characterisation of colonic lesions viewed under white light, chromoendoscopy and magnification chromoendoscopy.

MAIN OUTCOME MEASURES

Accuracy of characterisation of colonic lesions (hyperplastic vs adenoma vs cancer) before and after training and differences between groups (bowel cancer screening (BCS) nurses vs gastroenterology trainees vs consultant gastroenterologists).

RESULTS

Mean accuracy pretraining was 61.1%, 67.6% and 60.0% for the trainee, consultant and nurse groups respectively with no significant difference between the groups. Mean accuracy post-training improved significantly to 71.2%, 72.6% and 67.2% for the trainee, consultant and nurse groups (p<0.001 vs pretraining) with no significant difference between the three groups. Mean sensitivity and specificity improved significantly for the 15 participants overall.

CONCLUSIONS

The baseline level of colonic lesion characterisation skills is limited for gastroenterology consultants and trainees and does not differ from that of non-endoscopist BCS nurses. Accuracy of lesion characterisation can be modestly improved with a brief computer-based training intervention. Lesion characterisation should become a standard part of training in colonoscopy, and should be learnt alongside technical skills for endoscope handing and therapeutic procedures.

Report of the Association of Coloproctology of Great Britain and Ireland/British Society of Gastroenterology Colorectal Polyp Working Group: the development of a complex colorectal polyp minimum dataset

AIM

The management of large non-pedunculated colorectal polyps (LNPCPs) is complex, with widespread variation in management and outcome, even amongst experienced clinicians. Variations in the assessment and decision-making processes are likely to be a major factor in this variability. The creation of a standardized minimum dataset to aid decision-making may therefore result in improved clinical management.

METHOD

An official working group of 13 multidisciplinary specialists was appointed by the Association of Coloproctology of Great Britain and Ireland (ACPGBI) and the British Society of Gastroenterology (BSG) to develop a minimum dataset on LNPCPs. The literature review used to structure the ACPGBI/BSG guidelines for the management of LNPCPs was used by a steering subcommittee to identify various parameters pertaining to the decision-making processes in the assessment and management of LNPCPs. A modified Delphi consensus process was then used for voting on proposed parameters over multiple voting rounds with at least 80% agreement defined as consensus. The minimum dataset was used in a pilot process to ensure rigidity and usability.

RESULTS

A 23-parameter minimum dataset with parameters relating to patient and lesion factors, including six parameters relating to image retrieval, was formulated over four rounds of voting with two pilot processes to test rigidity and usability.

CONCLUSION

This paper describes the development of the first reported evidence-based and expert consensus minimum dataset for the management of LNPCPs. It is anticipated that this dataset will allow comprehensive and standardized lesion assessment to improve decision-making in the assessment and management of LNPCPs.

Efficacy and safety of endoscopic resection of large colorectal polyps: a systematic review and meta-analysis

OBJECTIVE

To assess the efficacy and safety of endoscopic resection of large colorectal polyps.

DESIGN

Relevant publications were identified in MEDLINE/EMBASE/Cochrane Central Register for the period 1966-2014. Studies in which ≥20 mm colorectal neoplastic lesions were treated with endoscopic resection were included. Rates of postendoscopic resection surgery due to non-curative resection or adverse events, as well as the rates of complete endoscopic removal, invasive cancer, adverse events, recurrence and mortality, were extracted. Study quality was ascertained according to Newcastle-Ottawa Scale. Forest plot was produced based on random effect models. I2 statistic was used to describe the variation across studies due to heterogeneity. Meta-regression analysis was also performed.

RESULTS

50 studies including 6442 patients and 6779 large polyps were included in the analyses. Overall, 503 out of 6442 patients (pooled rate: 8%, 95% CI 7% to 10%, I2=78.6%) underwent surgery due to non-curative endoscopic resection, and 31/6442 (pooled rate: 1%, 95% CI 0.7% to 1.4%, I2=0%) to adverse events. Invasive cancer at histology, non-curative endoscopic resection, synchronous lesions and recurrence accounted for 58%, 28%, 2.2% and 5.9% of all the surgeries, respectively. Endoscopic perforation occurred in 96/6595 (1.5%, 95% CI 1.2% to 1.7%) polyps, while bleeding in 423/6474 (6.5%, 95% CI 5.9% to 7.1%). Overall, 5334 patients entered in surveillance, 502/5836 (8.6%, 95% CI 7.9% to 9.3%) being lost at follow-up. Endoscopic recurrence was detected in 735/5334 patients (13.8%, 95% CI 12.9% to 14.7%), being an invasive cancer in 14/5334 (0.3%, 95% CI 0.1% to 0.4%). Endoscopic treatment was successful in 664/735 cases (90.3%, 95% CI 88.2% to 92.5%). Mortality related with management of large polyps was reported in 5/6278 cases (0.08%, 95% CI 0.01% to 0.15%).

CONCLUSIONS

Endoscopic resection of large polyps appeared to be an extremely effective and safe intervention. However, an adequate endoscopic surveillance is necessary for its long-term efficacy.

Sideroblastic anemia

Sideroblastic anemias are a heterogenous group of disorders that have as a common feature with the presence of ringed sideroblasts in the marrow. We present a case of young female, nursing student who presented with increasing palpitation, fatigue and exertional shortness of breath for the last one year. She had a low hemoglobin and high serum iron. Anemia with iron overload prompted us to do bone marrow study and there were 19% ringed sideroblasts and iron overload fulfilling the diagnosis of sideroblastic anemia. We searched for secondary causes of ringed sideroblast but could not find any culprit. Her cytogenetics report was normal and genetic analysis was not done due to financial reason. Since the diagnosis 3 months back, patient is on pyridoxine, folic acid, deferasirox and still needs regular blood transfusion suggesting that she may be pyridoxine refractory and may develop iron overload.

Improvement over time in outcomes for patients undergoing endoscopic therapy for Barrett's oesophagus-related neoplasia: 6-year experience from the first 500 patients treated in the UK patient registry

BACKGROUND

Barrett's oesophagus (BE) is a pre-malignant condition leading to oesophageal adenocarcinoma (OAC). Treatment of neoplasia at an early stage is desirable. Combined endoscopic mucosal resection (EMR) followed by radiofrequency ablation (RFA) is an alternative to surgery for patients with BE-related neoplasia.

METHODS

We examined prospective data from the UK registry of patients undergoing RFA/EMR for BE-related neoplasia from 2008 to 2013. Before RFA, visible lesions were removed by EMR. Thereafter, patients had RFA 3-monthly until all BE was ablated or cancer developed (endpoints). End of treatment biopsies were recommended at around 12 months from first RFA treatment or when endpoints were reached. Outcomes for clearance of dysplasia (CR-D) and BE (CR-IM) at end of treatment were assessed over two time periods (2008-2010 and 2011-2013). Durability of successful treatment and progression to OAC were also evaluated.

RESULTS

508 patients have completed treatment. CR-D and CR-IM improved significantly between the former and later time periods, from 77% and 56% to 92% and 83%, respectively (p<0.0001). EMR for visible lesions prior to RFA increased from 48% to 60% (p=0.013). Rescue EMR after RFA decreased from 13% to 2% (p<0.0001). Progression to OAC at 12 months is not significantly different (3.6% vs 2.1%, p=0.51).

CONCLUSIONS

Clinical outcomes for BE neoplasia have improved significantly over the past 6 years with improved lesion recognition and aggressive resection of visible lesions before RFA. Despite advances in technique, the rate of cancer progression remains 2-4% at 1 year in these high-risk patients.

TRIAL REGISTRATION NUMBER

ISRCTN93069556.

Dissociation of mitochondrial from sarcoplasmic reticular stress in Drosophila cardiomyopathy induced by molecularly distinct mitochondrial fusion defects

Mitochondrial dynamism (fusion and fission) is responsible for remodeling interconnected mitochondrial networks in some cell types. Adult cardiac myocytes lack mitochondrial networks, and their mitochondria are inherently "fragmented". Mitochondrial fusion/fission is so infrequent in cardiomyocytes as to not be observable under normal conditions, suggesting that mitochondrial dynamism may be dispensable in this cell type. However, we previously observed that cardiomyocyte-specific genetic suppression of mitochondrial fusion factors optic atrophy 1 (Opa1) and mitofusin/MARF evokes cardiomyopathy in Drosophila hearts. We posited that fusion-mediated remodeling of mitochondria may be critical for cardiac homeostasis, although never directly observed. Alternately, we considered that inner membrane Opa1 and outer membrane mitofusin/MARF might have other as-yet poorly described roles that affect mitochondrial and cardiac function. Here we compared heart tube function in three models of mitochondrial fragmentation in Drosophila cardiomyocytes: Drp1 expression, Opa1 RNAi, and mitofusin MARF RNA1. Mitochondrial fragmentation evoked by enhanced Drp1-mediated fission did not adversely impact heart tube function. In contrast, RNAi-mediated suppression of either Opa1 or mitofusin/MARF induced cardiac dysfunction associated with mitochondrial depolarization and ROS production. Inhibiting ROS by overexpressing superoxide dismutase (SOD) or suppressing ROMO1 prevented mitochondrial and heart tube dysfunction provoked by Opa1 RNAi, but not by mitofusin/MARF RNAi. In contrast, enhancing the ability of endoplasmic/sarcoplasmic reticulum to handle stress by expressing Xbp1 rescued the cardiomyopathy of mitofusin/MARF insufficiency without improving that caused by Opa1 deficiency. We conclude that decreased mitochondrial size is not inherently detrimental to cardiomyocytes. Rather, preservation of mitochondrial function by Opa1 located on the inner mitochondrial membrane, and prevention of ER stress by mitofusin/MARF located on the outer mitochondrial membrane, are central functions of these "mitochondrial fusion proteins".

Mitochondrial genome linearization is a causative factor for cardiomyopathy in mice and Drosophila

AIMS

Mitofusin (Mfn)2 redundantly promotes mitochondrial outer membrane tethering and organelle fusion with Mfn1, and uniquely functions as the mitochondrial receptor for Parkin during PTEN-induced putative kinase 1 (PINK1)-Parkin-mediated mitophagy. Selective deletion of Mfn2 with retention of Mfn1 preserves mitochondrial fusion while rendering damaged mitochondria resistant to normal quality control culling mechanisms. Consequently, neuron and cardiomyocyte-specific Mfn2 gene ablation is associated with accumulation of damaged mitochondria and organ dysfunction. Here, we determined how mitochondrial DNA (mtDNA) damage contributes to cardiomyopathy in Mfn2-deficient hearts.

RESULTS

RNA sequencing of Mfn2-deficient hearts revealed increased expression of some nuclear-encoded mitochondrial genes, but mitochondrial-encoded transcripts were not upregulated in parallel and mtDNA content was decreased. Ultra-deep sequencing of mtDNA showed no increase in single nucleotide mutations, but copy number variations representing insertion-deletion (in-del) mutations were induced over time by cardiomyocyte-specific Mfn2 deficiency. Double-strand mtDNA breaks in the form of in-dels were confirmed by polymerase chain reaction, and in the form of linear mitochondrial genomes were identified by southern blot analysis. Linearization of Drosophila cardiomyocyte mtDNA using conditional cardiomyocyte-specific expression of mitochondrial targeted XhoI recapitulated the cardiomyopathy of Mfn2-deficient mouse hearts.

INNOVATION

This is the first description of mitochondrial genome linearization as a causative factor in cardiomyopathy.

CONCLUSION

One of the consequences of interrupting mitochondrial culling by the PINK1-Mfn2-Parkin mechanism is an increase in mtDNA double-stranded breaks, which adversely impact mitochondrial function and DNA replication.

Mitochondrial contagion induced by Parkin deficiency in Drosophila hearts and its containment by suppressing mitofusin

RATIONALE

Dysfunctional Parkin-mediated mitophagic culling of senescent or damaged mitochondria is a major pathological process underlying Parkinson disease and a potential genetic mechanism of cardiomyopathy. Despite epidemiological associations between Parkinson disease and heart failure, the role of Parkin and mitophagic quality control in maintaining normal cardiac homeostasis is poorly understood.

OBJECTIVE

We used germline mutants and cardiac-specific RNA interference to interrogate Parkin regulation of cardiomyocyte mitochondria and examine functional crosstalk between mitophagy and mitochondrial dynamics in Drosophila heart tubes.

METHODS AND RESULTS

Transcriptional profiling of Parkin knockout mouse hearts revealed compensatory upregulation of multiple related E3 ubiquitin ligases. Because Drosophila lack most of these redundant genes, we examined heart tubes of parkin knockout flies and observed accumulation of enlarged hollow donut mitochondria with dilated cardiomyopathy, which could be rescued by cardiomyocyte-specific Parkin expression. Identical abnormalities were induced by cardiomyocyte-specific Parkin suppression using 2 different inhibitory RNAs. Parkin-deficient cardiomyocyte mitochondria exhibited dysmorphology, depolarization, and reactive oxygen species generation without calcium cycling abnormalities, pointing to a primary mitochondrial defect. Suppressing cardiomyocyte mitochondrial fusion in Parkin-deficient fly heart tubes completely prevented the cardiomyopathy and corrected mitochondrial dysfunction without normalizing mitochondrial dysmorphology, demonstrating a central role for mitochondrial fusion in the cardiomyopathy provoked by impaired mitophagy.

CONCLUSIONS

Parkin deficiency and resulting mitophagic disruption produces cardiomyopathy in part by contamination of the cardiomyocyte mitochondrial pool through fusion between improperly retained dysfunctional/senescent and normal mitochondria. Limiting mitochondrial contagion by inhibiting organelle fusion shows promise for minimizing organ dysfunction produced by defective mitophagic signaling.

A novel method for determining the difficulty of colonoscopic polypectomy

INTRODUCTION

Endoscopists are now expected to perform polypectomy routinely. Colonic polypectomy varies in difficulty, depending on polyp morphology, size, location and access. The measurement of the degree of difficulty of polypectomy, based on polyp characteristics, has not previously been described.

OBJECTIVE

To define the level of difficulty of polypectomy.

METHODS

Consensus by nine endoscopists regarding parameters that determine the complexity of a polyp was achieved through the Delphi method. The endoscopists then assigned a polyp complexity level to each possible combination of parameters. A scoring system to measure the difficulty level of a polyp was developed and validated by two different expert endoscopists.

RESULTS

Through two Delphi rounds, four factors for determining the complexity of a polypectomy were identified: size (S), morphology (M), site (S) and access (A). A scoring system was established, based on size (1-9 points), morphology (1-3 points), site (1-2 points) and access (1-3 points). Four polyp levels (with increasing level of complexity) were identified based on the range of scores obtained: level I (4-5), level II (6-9), level III (10-12) and level IV (>12). There was a high degree of interrater reliability for the polyp scores (interclass correlation coefficient of 0.93) and levels (κ=0.888).

CONCLUSIONS

The scoring system is feasible and reliable. Defining polyp complexity levels may be useful for planning training, competency assessment and certification in colonoscopic polypectomy. This may allow for more efficient service delivery and referral pathways.

HLA antigen distribution in renal transplant recipients and donors

BACKGROUND

HLA typing analysis is important in renal transplant patient. This study is the first report from Nepal to find out distribution of HLA A, B, DR antigen in live related renal transplant recipients and donors from Nepal. The aim of this study was to investigate the distribution of HLA in the live related renal transplant recipients and donors of Nepal.

METHODS

In a retrospective study, HLA patterns were defined in 100 live related renal transplant recipients and donors. One year study is done from June 2011 to May 2012. The study was done by using sequence specific oligonucleotides primers and polymerase chain reaction and assay. Allele frequencies were obtained by direct counting.

RESULTS

A total of 12 HLA-A, 15 HLA-B and 13 HLA-DRB1 alleles were identified at the four-digit level in the live related renal transplant recipients and donors of Nepal. High frequency alleles were HLA-A*11 (34.5%), A*24 (17%), A*33 (13%); HLA-B*15(27%), B*35(19%), B*40 (10%); HLA-DRB1*15 (33.5%), DRB1*12 (21.4%) and DRB1*04 (7.32%).

CONCLUSIONS

These results showed considerable heterogeneity in both HLA class I and class II antigens. To reduce the risk of allograft rejection, transplantation from HLA matched donors is recommended.

Duration of acetowhitening as a novel objective tool for diagnosing high risk neoplasia in Barrett's esophagus: a prospective cohort trial

BACKGROUND AND STUDY AIMS

Acetic acid reacts with Barrett's mucosa to produce acetowhitening which disappears with time. The clinical significance of this is unknown. We aimed to quantify the acetowhitening time, developing an objective tool for diagnosis of neoplasia in Barrett's esophagus.

PATIENTS AND METHODS

Prospective cohort study in a tertiary referral center, enrolling patients undergoing surveillance of Barrett's metaplasia or referred with suspected neoplasia. Acetic acid 2.5 % was applied to the mucosa via a spray catheter. Acetowhitening was observed and time to disappearance recorded. Targeted biopsies of any neoplasia and quadrantic 2-cm biopsies of residual Barrett's area were then taken. Histological findings were investigated in relation to duration of acetowhitening.

RESULTS

132 patients were examined. A receiver operating characteristic (ROC) curve was produced for identifying high risk neoplasia according to acetowhitening duration. The area under the curve (AUC) was 0.93 (0.89 - 0.97). Using a threshold of 142 seconds yielded a sensitivity for neoplasia of 98 % (95 % confidence interval [95 %CI] 89 % - 100 %) and specificity of 84 % (74 % - 91 %). The ROC curve for mucosal neoplasia (high grade dysplasia or intramucosal carcinoma) versus deep invasive cancer showed an AUC of 0.786 (0.61 - 0.96); a cutoff of 20 seconds yielded a sensitivity and specificity for invasive cancer of 67 % (35 % - 90 %) and 85 % (69 % - 95 %), respectively.

CONCLUSION

The time to disappearance of acetowhitening can serve as a simple but very sensitive tool for the diagnosis of high risk neoplasia in Barrett's esophagus. It can be used to distinguish mucosal neoplasia from deep invasive cancer.

High-definition vs. standard-definition colonoscopy in the characterization of small colonic polyps: results from a randomized trial

BACKGROUND AND STUDY AIMS

The resolution of endoscopes has increased in recent years. Modern Fujinon colonoscopes have a charge-coupled device (CCD) pixel density of 650,000 pixels compared with the 410,000 pixel CCD in standard-definition scopes. Acquiring high-definition scopes represents a significant capital investment and their clinical value remains uncertain. The aim of the current study was to investigate the impact of high-definition endoscopes on the in vivo histology prediction of colonic polyps.

PATIENTS AND METHODS

Colonoscopy procedures were performed using Fujinon colonoscopes and EPX-4400 processor. Procedures were randomized to be performed using either a standard-definition EC-530 colonoscope or high-definition EC-530 and EC-590 colonoscopes. Polyps of <10 mm were assessed using both white light imaging (WLI) and flexible spectral imaging color enhancement (FICE), and the predicted diagnosis was recorded. Polyps were removed and sent for histological analysis by a pathologist who was blinded to the endoscopic diagnosis. The predicted diagnosis was compared with the histology to calculate the accuracy, sensitivity, and specificity of in vivo assessment using either standard or high-definition scopes.

RESULTS

A total of 293 polyps of <10 mm were examined–150 polyps using the standard-definition colonoscope and 143 polyps using high-definition colonoscopes. There was no difference in sensitivity, specificity or accuracy between the two scopes when WLI was used (standard vs. high: accuracy 70% [95% CI 62–77] vs. 73% [95% CI 65–80]; P=0.61). When FICE was used, high-definition colonoscopes showed a sensitivity of 93% compared with 83% for standard-definition colonoscopes (P=0.048); specificity was 81% and 82%, respectively.

CONCLUSIONS

There was no difference between high- and standard-definition colonoscopes when white light was used, but FICE significantly improved the in vivo diagnosis of small polyps when high-definition scopes were used compared with standard definition.

Two rare human mitofusin 2 mutations alter mitochondrial dynamics and induce retinal and cardiac pathology in Drosophila

Mitochondrial fusion is essential to organelle homeostasis and organ health. Inexplicably, loss of function mutations of mitofusin 2 (Mfn2) specifically affect neurological tissue, causing Charcot Marie Tooth syndrome (CMT) and atypical optic atrophy. As CMT-linked Mfn2 mutations are predominantly within the GTPase domain, we postulated that Mfn2 mutations in other functional domains might affect non-neurological tissues. Here, we defined in vitro and in vivo consequences of rare human mutations in the poorly characterized Mfn2 HR1 domain. Human exome sequencing data identified 4 rare non-synonymous Mfn2 HR1 domain mutations, two bioinformatically predicted as damaging. Recombinant expression of these (Mfn2 M393I and R400Q) in Mfn2-null murine embryonic fibroblasts (MEFs) revealed incomplete rescue of characteristic mitochondrial fragmentation, compared to wild-type human Mfn2 (hMfn2); Mfn2 400Q uniquely induced mitochondrial fragmentation in normal MEFs. To compare Mfn2 mutation effects in neurological and non-neurological tissues in vivo, hMfn2 and the two mutants were expressed in Drosophila eyes or heart tubes made deficient in endogenous fly mitofusin (dMfn) through organ-specific RNAi expression. The two mutants induced similar Drosophila eye phenotypes: small eyes and an inability to rescue the eye pathology induced by suppression of dMfn. In contrast, Mfn2 400Q induced more severe cardiomyocyte mitochondrial fragmentation and cardiac phenotypes than Mfn2 393I, including heart tube dilation, depressed fractional shortening, and progressively impaired negative geotaxis. These data reveal a central functional role for Mfn2 HR1 domains, describe organ-specific effects of two Mfn2 HR1 mutations, and strongly support prospective studies of Mfn2 400Q in heritable human heart disease of unknown genetic etiology.

Acetic acid-enhanced chromoendoscopy is more cost-effective than protocol-guided biopsies in a high-risk Barrett's population

To examine the efficacy and potential cost implications of acetic acid (AA) chromoendoscopy in the assessment of Barrett's neoplasia. Our prospective database of patients referred between 2005 and 2010 with suspected early neoplasia was reviewed. High-resolution Fujinon gastroscopes and EPX-4400 processor were used. Inspection of Barrett's neoplasia was carried out using white light followed by AA. Neoplastic areas were noted, and targeted biopsy was carried out. This was followed by quadrantic biopsies of the remaining Barrett's neoplasia. The cost of protocol-guided biopsies was compared with AA-guided biopsy protocols. Two hundred sixty-three procedures on 197 patients were examined. High-risk neoplasia was found during 143 procedures. In 96% of cases it was identified with AA. The cost of histological evaluation by Cleveland protocol would be £139,416.30. The cost by AA-targeted biopsy followed by random biopsies in one pot would be £25,032.50. For AA-targeted biopsies alone the cost would be £9,541.8 but results in a 4% miss rate. AA localizes neoplastic lesions in the majority of patients and could potentially represent a significant cost saving in patients with suspected neoplasia.

Chloride intracellular channels modulate acute ethanol behaviors in Drosophila, Caenorhabditis elegans and mice

Identifying genes that influence behavioral responses to alcohol is critical for understanding the molecular basis of alcoholism and ultimately developing therapeutic interventions for the disease. Using an integrated approach that combined the power of the Drosophila, Caenorhabditis elegans and mouse model systems with bioinformatics analyses, we established a novel, conserved role for chloride intracellular channels (CLICs) in alcohol-related behavior. CLIC proteins might have several biochemical functions including intracellular chloride channel activity, modulation of transforming growth factor (TGF)-β signaling, and regulation of ryanodine receptors and A-kinase anchoring proteins. We initially identified vertebrate Clic4 as a candidate ethanol-responsive gene via bioinformatic analysis of data from published microarray studies of mouse and human ethanol-related genes. We confirmed that Clic4 expression was increased by ethanol treatment in mouse prefrontal cortex and also uncovered a correlation between basal expression of Clic4 in prefrontal cortex and the locomotor activating and sedating properties of ethanol across the BXD mouse genetic reference panel. Furthermore, we found that disruption of the sole Clic Drosophila orthologue significantly blunted sensitivity to alcohol in flies, that mutations in two C. elegans Clic orthologues, exc-4 and exl-1, altered behavioral responses to acute ethanol in worms and that viral-mediated overexpression of Clic4 in mouse brain decreased the sedating properties of ethanol. Together, our studies demonstrate key roles for Clic genes in behavioral responses to acute alcohol in Drosophila, C. elegans and mice.

Circulating tumour markers can define patients with normal colons, benign polyps, and cancers

Background:

Early diagnosis represents the best opportunity for cure of colorectal cancer. Current screening programmes use faecal occult blood testing for screening, which has limited sensitivity and poor specificity.

Methods:

In this study we looked at a series of previously described diagnostic markers utilising circulating free DNA (cfDNA), with a preparation method allowing small DNA fragments to be isolated. The Circulating free DNA was isolated from samples obtained from 85 patients, including 35 patients without endoscopic abnormality, a group of 26 patients with benign colorectal adenomas, and 24 patients with colorectal carcinomas. In each case, polymerase chain reaction (PCR) was performed for Line1 79 bp, Line1 300 bp, Alu 115 bp, Alu 247 bp, and mitochondrial primers. In addition, carcinoembryonic antigen (CEA) was measured by ELISA. Each marker was analysed between normal, polyp, and cancer populations, and the best performing analysed in combination by logistic regression.

Results:

The best model was able to discriminate normal from populations with adenoma or carcinoma using three DNA markers and CEA, showing an area under the receiver operator characteristic (ROC) curve of 0.855 with a positive predictive value of 81.1% for polyps and cancer diagnosis.

Conclusion:

These circulating markers in combination with other markers offer the prospect of a simple blood test as a possible secondary screen for colorectal cancers and polyps in patients with positive faecal occult blood tests.

Use of Gascon and Pronase either as a pre-endoscopic drink or as targeted endoscopic flushes to improve visibility during gastroscopy: a prospective, randomized, controlled, blinded trial

OBJECTIVE

To assess whether endoscopic flushes of the bubble-bursting agent Gascon and the mucolytic agent Pronase are as effective in terms of improving endoscopic mucosal visibility as a pre-endoscopic drink of the same agents.

MATERIAL AND METHODS

A total of 112 patients attending a Japanese tertiary referral centre for upper gastrointestinal endoscopy were randomized to receive either the standard Japanese procedure of a pre-endoscopic drink of water containing Gascon and Pronase with endoscopic flushes of 20-ml aliquots of water, or no pre-endoscopic therapy but endoscopic flushes of 20-ml aliquots of water containing Gascon, with or without Pronase as necessary.

RESULTS

Visibility scores were significantly better in the pre-endoscopic drink group than in either of the endoscopic flush groups. The group receiving a pre-endoscopic drink required fewer flushes during the procedure and there was no difference in the endoscopic time between the three groups.

CONCLUSIONS

Our results suggest that endoscopic spraying of these bubble-bursting and mucolytic agents is not able to offer equivalent improvements in endoscopic mucosal visibility when compared with the standard Japanese therapy of a pre-endoscopic drink of these agents. The addition of Pronase to the spray solution had no measurable benefit over Gascon alone. We therefore cannot recommend endoscopic spraying of mucous clearing agents over their use as a pre-endoscopic drink.

An assay for evoked locomotor behavior in Drosophila reveals a role for integrins in ethanol sensitivity and rapid ethanol tolerance

BACKGROUND

Ethanol induces similar behavioral responses in mammals and the fruit fly, Drosophila melanogaster. By coupling assays for ethanol-related behavior to the genetic tools available in flies, a number of genes have been identified that influence physiological responses to ethanol. To enhance the utility of the Drosophila model for investigating genes involved in ethanol-related behavior, we explored the value of an assay that measures the sedative effects of ethanol on negative geotaxis, an evoked locomotor response.

METHODS

We established eRING (ethanol Rapid Iterative Negative Geotaxis) as an assay for quantitating the sedative effects of ethanol on negative geotaxis (i.e., startle-induced climbing). We validated the assay by assessing acute sensitivity to ethanol and rapid ethanol tolerance in several different control strains and in flies with mutations known to disrupt these behaviors. We also used eRING in a candidate screen to identify mutants with altered ethanol-related behaviors.

RESULTS

Negative geotaxis measured in eRING assays was dose-dependently impaired by ethanol exposure. Flies developed tolerance to the intoxicating effects of ethanol when tested during a second exposure. Ethanol sensitivity and rapid ethanol tolerance varied across 4 control strains, but internal ethanol concentrations were indistinguishable in the 4 strains during a first and second challenge with ethanol. Ethanol sensitivity and rapid ethanol tolerance, respectively, were altered in flies with mutations in amnesiac and hangover, genes known to influence these traits. Additionally, mutations in the beta integrin gene myospheroid and the alpha integrin gene scab increased the initial sensitivity to ethanol and enhanced the development of rapid ethanol tolerance without altering internal ethanol concentrations.

CONCLUSIONS

The eRING assay is suitable for investigating genetic mechanisms that influence ethanol sensitivity and rapid ethanol tolerance. Ethanol sensitivity and rapid ethanol tolerance depend on the function of alpha and beta integrins in flies.

A forward genetic screen in Drosophila implicates insulin signaling in age-related locomotor impairment

Age-related locomotor impairment (ARLI) is one of the most detrimental changes that occurs during aging. Elderly individuals with ARLI are at increased risks for falls, depression and a number of other co-morbidities. Despite its clinical significance, little is known about the genes that influence ARLI. We consequently performed a forward genetic screen to identify Drosophila strains with delayed ARLI using negative geotaxis as an index of locomotor function. One of the delayed ARLI strains recovered from the screen had a P-element insertion that decreased expression of the insulin signaling gene phosphoinositide-dependent kinase 1 (PDK1) Precise excision of the P-element insertion reverted PDK1 expression and ARLI to the same as control flies, indicating that disruption of PDK1 leads to delayed ARLI. Follow-up studies showed that additional loss of function mutations in PDK1 as well as loss of function alleles of two other insulin signaling genes, Dp110 and Akt (the genes for the catalytic subunit of phosphoinositide 3-kinase and AKT), also forestalled ARLI. Interestingly, only some of the strains with delayed ARLI had elevated resistance to paraquat, indicating that enhanced resistance to this oxidative stressor is not required for preservation of locomotor function across age. Our studies implicate insulin signaling as a key regulator of ARLI in Drosophila.

Is there an association between intestinal perfusion and Crohn's disease activity? A feasibility study using contrast-enhanced ultrasound

A recent study used contrast-enhanced ultrasound to assess splanchnic haemodynamics. This study investigates whether an association exists between disease activity and splanchnic transit time in patients with suspected Crohn's disease. The study protocol had the approval of the local ethics committee, and written informed consent was obtained. 18 patients (11 women; mean age, 40 years; age range, 23-69 years) with suspected or confirmed Crohn's disease were recruited prospectively. A bolus injection of an ultrasound contrast agent was given via a peripheral vein and time-intensity curves of the superior mesenteric artery and vein were analysed. Splanchnic transit time was calculated as the time interval between the rise in signal intensity to >10% above baseline value. Baseline parameters measured included the time-averaged maximum velocity and cross-sectional area of the superior mesenteric artery (SMA). Pearson correlations were used to test associations between different numeric measurements; the independent samples t-test was used to test associations between different numeric measurements; and the independent samples t-test was used to compare mean values between patients with active and inactive disease. There was a weak negative association between splanchnic transit time and the Crohn's Disease Activity Index (CDAI) (r = -0.42), which did not reach statistical significance (p = 0.13), although the mean splanchnic transit time was reduced in the active group (4.0 s vs 6.9 s). The SMA flow rate was significantly greater in active disease (37 ml s(-1) vs 22 ml s(-1); Mann-Whitney U, p = 0.02). This study demonstrates the feasibility of using contrast-enhanced ultrasound as an assessment tool for Crohn's disease.

Individual crypt genetic heterogeneity and the origin of metaplastic glandular epithelium in human Barrett's oesophagus

OBJECTIVES

Current models of clonal expansion in human Barrett's oesophagus are based upon heterogenous, flow-purified biopsy analysis taken at multiple segment levels. Detection of identical mutation fingerprints from these biopsy samples led to the proposal that a mutated clone with a selective advantage can clonally expand to fill an entire Barrett's segment at the expense of competing clones (selective sweep to fixation model). We aimed to assess clonality at a much higher resolution by microdissecting and genetically analysing individual crypts. The histogenesis of Barrett's metaplasia and neo-squamous islands has never been demonstrated. We investigated the oesophageal gland squamous ducts as the source of both epithelial sub-types.

METHODS

Individual crypts across Barrett's biopsy and oesophagectomy blocks were dissected. Determination of tumour suppressor gene loss of heterozygosity patterns, p16 and p53 point mutations were carried out on a crypt-by-crypt basis. Cases of contiguous neo-squamous islands and columnar metaplasia with oesophageal squamous ducts were identified. Tissues were isolated by laser capture microdissection and genetically analysed.

RESULTS

Individual crypt dissection revealed mutation patterns that were masked in whole biopsy analysis. Dissection across oesophagectomy specimens demonstrated marked clonal heterogeneity, with multiple independent clones present. We identified a p16 point mutation arising in the squamous epithelium of the oesophageal gland duct, which was also present in a contiguous metaplastic crypt, whereas neo-squamous islands arising from squamous ducts were wild-type with respect to surrounding Barrett's dysplasia.

CONCLUSIONS

By studying clonality at the crypt level we demonstrate that Barrett's heterogeneity arises from multiple independent clones, in contrast to the selective sweep to fixation model of clonal expansion previously described. We suggest that the squamous gland ducts situated throughout the oesophagus are the source of a progenitor cell that may be susceptible to gene mutation resulting in conversion to Barrett's metaplastic epithelium. Additionally, these data suggest that wild-type ducts may be the source of neo-squamous islands.

Genetic and environmental factors impact age-related impairment of negative geotaxis in Drosophila by altering age-dependent climbing speed

Age-related locomotor impairment in humans is important clinically because it is associated with several co-morbidities and increased risk of death. One of the hallmarks of age-related locomotor impairment in humans is a decrease in walking speed with age. Genetically tractable model organisms such as Drosophila are essential for delineating mechanisms underlying age-related locomotor impairment and age-related decreases in locomotor speed. Negative geotaxis, the ability of flies to move vertically when startled, is a common measure of locomotor behavior that declines with age in Drosophila. Toward further developing Drosophila as a model for age-related locomotor impairment, we investigated whether negative geotaxis reflects climbing or a combination of climbing and other behaviors such as flying and jumping. Additionally, we investigated whether locomotor speed in negative geotaxis assays declines with age in flies as found for walking speed in humans. We find that the vast majority of flies climb during negative geotaxis assays and that removal of hind legs, but not wings, impairs the behavior. We also find that climbing speed decreases with age in four wild type genetic backgrounds, in flies housed at different temperatures, and in control and long-lived flies harboring a mutation in OR83b. The decreases in climbing speed correlate with the age-related impairments in the distance climbed. These studies establish negative geotaxis in Drosophila as a climbing behavior that declines with age due to a decrease in climbing speed. Age-related decreases in locomotor speed are common attributes of locomotor senescence in flies and humans.

Dietary restriction alters demographic but not behavioral aging in Drosophila

Dietary restriction extends lifespan substantially in numerous species including Drosophila. However, it is unclear whether dietary restriction in flies impacts age-related functional declines in conjunction with its effects on lifespan. Here, we address this issue by assessing the effect of dietary restriction on lifespan and behavioral senescence in two wild-type strains, in our standard white laboratory stock, and in short-lived flies with reduced expression of superoxide dismutase 2. As expected, dietary restriction extended lifespan in all of these strains. The effect of dietary restriction on lifespan varied with genetic background, ranging from 40 to 90% extension of median lifespan in the seven strains tested. Interestingly, despite its robust positive effects on lifespan, dietary restriction had no substantive effects on senescence of behavior in any of the strains in our studies. Our results suggest that dietary restriction does not have a global impact on aging in Drosophila and support the hypothesis that lifespan and behavioral senescence are not driven by identical mechanisms.

Behavioral Responses to Odorants in Drosophila Require Nervous System Expression of the Integrin Gene Myospheroid

Integrins are cell adhesion molecules that mediate numerous developmental processes in addition to a variety of acute physiological events. Two reports implicate a Drosophila beta integrin, betaPS, in olfactory behavior. To further investigate the role of integrins in Drosophila olfaction, we used Gal4-driven expression of RNA interference (RNAi) transgenes to knock down expression of myospheroid (mys), the gene that encodes betaPS. Expression of mys-RNAi transgenes in the wing reduced betaPS immunostaining and produced morphological defects associated with loss-of-function mutations in mys, demonstrating that this strategy knocked down mys function. Expression of mys-RNAi transgenes in the antennae, antennal lobes, and mushroom bodies via two Gal4 lines, H24 and MT14, disrupted olfactory behavior but did not alter locomotor abilities or central nervous system structure. Olfactory behavior was normal in flies that expressed mys-RNAi transgenes via other Gal4 lines that specifically targeted the antennae, the projection neurons, the mushroom bodies, bitter and sweet gustatory neurons, or Pox neuro neurons. Our studies confirm that mys is important for the development or function of the Drosophila olfactory system. Additionally, our studies demonstrate that mys is required for normal behavioral responses to both aversive and attractive odorants. Our results are consistent with a model in which betaPS mediates events within the antennal lobes that influence odorant sensitivity.