Eight-year retrospective study investigating tooth survival after primary non-surgical root canal treatment in a UK military cohort

INTRODUCTION

Root canal treatment (RCT) plays an important role in preserving the dentition by deferring other invasive treatments. Data on tooth survival and predictive factors for tooth loss after RCT in the military cohort are lacking. This investigation aimed to determine the proportion of teeth surviving in an 8-year period after RCT and identify potential predictive factors for tooth loss in a UK military cohort.

METHODOLOGY

A retrospective review of an integrated electronic health record for military patients who had received RCT was performed in a random sample of 205 patients (n=219 root-filled teeth) who had received RCT between 1 January 2011 and 1 January 2012. Tooth survival was defined as tooth presence, regardless of signs or symptoms, and measured from the point of root filling until either the end of the designated study period or time of extraction. Survival was evaluated using Kaplan-Meier estimates and association with tooth loss using the χ2 test. Potentially significant predictive factors were investigated using univariate Cox regression.

RESULTS

Tooth survival following RCT was 98% after 24 months; 88% after 48 months; 83% after 72 months; and 78% after 96 months. Four predictive factors were found to affect tooth loss as follows: preoperative pain (HR=3.2; p<0.001), teeth with less than two proximal contacts (HR=3.0; p=0.01), teeth with cores involving more than two surfaces (HR=2.0; p=0.03) and postoperative unscheduled dental attendances (UDA) (HR=2.7; p=0.01).

CONCLUSIONS

Within the limitations of this study, the presence of preoperative pain; teeth with less than two proximal contacts or with cores involving more than two tooth surfaces; and occurrence of postoperative UDA were found to significantly increase the hazard of tooth loss.

Hs27 fibroblast response to contact guidance cues

Contact guidance is the phenomena of how cells respond to the topography of their external environment. The morphological and dynamic cell responses are strongly influenced by topographic features such as lateral and vertical dimensions, namely, ridge and groove widths and groove depth ([Formula: see text], respectively). However, experimental studies that independently quantify the effect of the individual dimensions as well as their coupling on cellular function are still limited. In this work, we perform extensive parametric studies in the dimensional space-well beyond the previously studied range in the literature-to explore topographical effects on morphology and migration of Hs27 fibroblasts via static and dynamic analyses of live cell images. Our static analysis reveals that the [Formula: see text] is most significant, followed by the [Formula: see text]. The fibroblasts appear to be more elongated and aligned in the groove direction as the [Formula: see text] increases, but their trend changes after 725 nm. Interestingly, the cell shape and alignment show a very strong correlation regardless of [Formula: see text]. Our dynamic analysis confirms that directional cell migration is also strongly influenced by the [Formula: see text], while the effect of the [Formula: see text] and [Formula: see text] is statistically insignificant. Directional cell migration, as observed in the static cell behavior, shows the statistically significant transition when the [Formula: see text] is 725 nm, showing the intimate links between cell morphology and migration. We propose possible scenarios to offer mechanistic explanations of the observed cell behavior.

In silico interrogation of the miRNAome of infected hematopoietic cells to predict processes important for human cytomegalovirus latent infection

Human cytomegalovirus (HCMV) latency in CD34+ progenitor cells is the outcome of a complex and continued interaction of virus and host that is initiated during very early stages of infection and reflects pro- and anti-viral activity. We hypothesized that a key event during early infection could involve changes to host miRNAs, allowing for rapid modulation of the host proteome. Here, we identify 72 significantly upregulated miRNAs and three that were downregulated by 6hpi of infection of CD34+ cells which were then subject to multiple in silico analyses to identify potential genes and pathways important for viral infection. The analyses focused on the upregulated miRNAs and were used to predict potential gene hubs or common mRNA targets of multiple miRNAs. Constitutive deletion of one target, the transcriptional regulator JDP2, resulted in a defect in latent infection of myeloid cells; interestingly, transient knockdown in differentiated dendritic cells resulted in increased viral lytic IE gene expression, arguing for subtle differences in the role of JDP2 during latency establishment and reactivation of HCMV. Finally, in silico predictions identified clusters of genes with related functions (such as calcium signaling, ubiquitination, and chromatin modification), suggesting potential importance in latency and reactivation. Consistent with this hypothesis, we demonstrate that viral IE gene expression is sensitive to calcium channel inhibition in reactivating dendritic cells. In conclusion, we demonstrate HCMV alters the miRNAome rapidly upon infection and that in silico interrogation of these changes reveals new insight into mechanisms controlling viral gene expression during HCMV latency and, intriguingly, reactivation.

The Global Retinoblastoma Outcome Study: a prospective, cluster-based analysis of 4064 patients from 149 countries

Background

Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival.

Methods

We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models.

Findings

The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope).

Interpretation

This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.

Funding

Queen Elizabeth Diamond Jubilee Trust.

P103 Impact of the COVID-19 pandemic on the sleep of patients of a multidisciplinary sleep clinic

Introduction

This study aimed to assess the impact of the COVID-19 pandemic on the sleep of adult patients of a multidisciplinary sleep clinic.

Methods

Patients were invited to complete online surveys: Survey 1 in October 2020 (increased COVID-19 restrictions) followed by Survey 2 in February 2021 (after easing of restrictions for a COVIDSafe summer).

Results

Of the 746 patients invited to participate, 73 completed and 8 partially returned Survey 1 (mean age 50.1 years, range 21–83 years, 58% female). Subsequently, 46 completed and 5 partially answered Survey 2. In Survey 1, 22/74 (29.7%) reported reduced sleep quantity and 31/75 (41.3%) indicated worse sleep quality compared with prior to the pandemic. In Survey 2, 33/46 (71.7%) described unchanged sleep quantity whilst 5/46 (10.9%) reported increased sleep quantity since easing COVID-19 restrictions. 36/46 (78.3%) indicated unchanged sleep quality whereas 5/46 (10.9%) described improved sleep quality since easing restrictions. However, 9/46 (19.6%) reported that their sleep remained worse compared with pre-pandemic. For patients who completed both surveys, there was no significant change in Insomnia Severity Index scores (Survey 1 mean 13.6, Survey 2 mean 12.9, mean difference -0.67 [95%CI -2.02, 0.68], p=0.32) or PROMIS Sleep-Related Impairment 8a T-scores (Survey 1 mean 59.0, Survey 2 mean 59.5, mean difference 0.44 [95%CI -1.55, 2.42], p=0.66).

Discussion

The COVID-19 pandemic has negatively affected the sleep of 44% of patients. Following easing of restrictions, symptoms of insomnia and sleep-related impairment did not change significantly, and 19.6% reported that their sleep was not back to their pre-pandemic baseline.

HOXC10 Suppresses Browning to Maintain White Adipocyte Identity

Promoting beige adipocyte development within white adipose tissue (WAT) is a potential therapeutic approach to staunch the current obesity epidemic. Previously, we identified homeobox-containing transcription factor HOXC10 as a suppressor of browning in subcutaneous WAT. Here, we provide evidence for the physiological role of HOXC10 in regulating WAT thermogenesis. Analysis of an adipose-specific HOXC10 knockout mouse line with no detectable HOXC10 in mature adipocytes revealed spontaneous subcutaneous WAT browning, increased expression of genes involved in browning, increased basal rectal temperature, enhanced cold tolerance, and improved glucose homeostasis. These phenotypes were further exacerbated by exposure to cold or a β-adrenergic stimulant. Mechanistically, cold and β-adrenergic exposure led to reduced HOXC10 protein level without affecting its mRNA level. Cold exposure induced cAMP-dependent protein kinase-dependent proteasome-mediated degradation of HOXC10 in cultured adipocytes, and shotgun proteomics approach identified KCTD2, 5, and 17 as potential E3 ligases regulating HOXC10 proteasomal degradation. Collectively, these data demonstrate that HOXC10 is a gatekeeper of WAT identity, and targeting HOXC10 could be a plausible therapeutic strategy to unlock WAT thermogenic potentials.

Nocturnal hypoxaemia in interstitial lung disease: a systematic review

BACKGROUND

Patients with interstitial lung disease (ILD) are at risk of developing nocturnal hypoxaemia due to ventilatory restriction and impaired gas exchange that worsen with supine posture and reduced ventilatory drive during sleep. This systematic review synthesised literature on the diagnostic evaluation, epidemiology, associations, management and prognosis of nocturnal hypoxaemia in ILD.

METHODS

Ovid MEDLINE, Embase and CENTRAL databases were searched for eligible studies. Meta-analyses with subgroup analyses were conducted, where possible.

RESULTS

Fifty-three studies were included (total participant number=2590). The most common definition for clinically significant nocturnal hypoxaemia was ≥10% of total sleep time with oxyhaemoglobin saturation <90%, with pooled prevalence of 37%. There were no significant differences in pooled prevalence according to ILD subtype and comorbid obstructive sleep apnoea status. Study heterogeneity precluded meta-analysis of associations and prognosis. Diffusing capacity for carbon monoxide (DLCO) and echocardiographic features for pulmonary hypertension were consistently associated with nocturnal hypoxaemia. There were inconsistent associations between nocturnal hypoxaemia with ILD subtype and severity. Multivariable analyses in most studies demonstrated significant associations of nocturnal hypoxaemia with survival. Two small short-term intervention studies demonstrated that supplemental oxygen of 1-3 L/min corrected nocturnal hypoxaemia, with improved heart rate control during in-laboratory observation and increased serum antioxidant levels after 1 month of therapy.

CONCLUSION

Nocturnal hypoxaemia is common, associated with DLCO impairment and markers suggestive of pulmonary hypertension, and a potential prognostic factor in patients in ILD. There is a need to establish a consensus definition of nocturnal hypoxaemia and evaluate long-term effects of nocturnal supplemental oxygen in ILD.

ASLAN003, a potent dihydroorotate dehydrogenase inhibitor for differentiation of acute myeloid leukemia

Differentiation therapies achieve remarkable success in acute promyelocytic leukemia, a subtype of acute myeloid leukemia. However, excluding acute promyelocytic leukemia, clinical benefits of differentiation therapies are negligible in acute myeloid leukemia except for mutant isocitrate dehydrogenase 1/2. Dihydroorotate dehydrogenase catalyses the fourth step of the de novo pyrimidine synthesis pathway. ASLAN003 is a highly potent dihydroorotate dehydrogenase inhibitor that induces differentiation, as well as reduces cell proliferation and viability, of acute myeloid leukemia cell lines and primary acute myeloid leukemia blasts including in chemo-resistant cells. Apoptotic pathways are triggered by ASLAN003, and it also significantly inhibits protein synthesis and activates AP-1 transcription, contributing to its differentiation promoting capacity. Finally, ASLAN003 substantially reduces leukemic burden and prolongs survival in acute myeloid leukemia xenograft mice and acute myeloid leukemia patient-derived xenograft models. Notably, the drug has no evident effect on normal hematopoietic cells and exhibits excellent safety profiles in mice, even after a prolonged period of administration. Our results, therefore, suggest that ASLAN003 is an agent targeting dihydroorotate dehydrogenase with potential in the treatment of acute myeloid leukemia. ASLAN003 is currently being evaluated in phase 2a clinical trial in acute myeloid leukemia patients.

Brief Report: Parent Perspectives on Sensory-Based Interventions for Children with Autism Spectrum Disorder

Sensory-Based Interventions (SBIs) are often recommended to enable function/participation in children with ASD. Still, there are limited studies to evaluate their effectiveness. Acceptability studies are an important step towards establishing effective interventions. We examined parents' perceptions of the uptake and acceptability of such interventions. An online survey was sent to 399 families; response rate was 39%. The most frequently therapist-recommended interventions were trampoline (54.6%), massage (47.8%), and oral-motor tools (43.8%). Highest use was reported for massage (96.3%), trampoline (89.2%) and joint compressions and brushing (89.2%). The majority of parents viewed these interventions to be very important /important, (74.8%) but barriers to their use were identified. High acceptability of SBIs was reported by parents of children with ASD.

Prognosis of idiopathic pulmonary fibrosis without anti-fibrotic therapy: a systematic review

In addition to facilitating healthcare delivery planning, reliable information about prognosis is essential for treatment decisions in patients with idiopathic pulmonary fibrosis (IPF). This review aimed to evaluate the prognosis of patients with IPF without anti-fibrotic therapy. We included all cohort studies and the placebo arms of randomised controlled trials (RCTs) in IPF and follow-up of ≥12 months. Two reviewers independently evaluated studies for inclusion, assessed risk of bias and extracted data. A total of 154 cohort studies and 16 RCTs were included. The pooled proportions of mortality were 0.12 (95% CI 0.09–0.14) at 1–2 years, 0.38 (95% CI 0.34–0.42) between 2–5 years, and 0.69 (95% CI 0.59–0.78) at ≥5 years. The pooled mean overall survival was 4 years (95% CI 3.7–4.6) for studies with a follow-up duration of 10 years. At <2 years, forced vital capacity and diffusing capacity of the lung for carbon monoxide declined by a mean of 6.76% predicted (95% CI −8.92 −4.61) and 3% predicted (95% CI −5.14 −1.52), respectively. Although heterogeneity was high, subgroup analyses revealed lower pooled proportions of mortality at 1 year in the RCT participants (0.07 (95% CI 0.05–0.09)) versus cohort study participants (0.14 (95% CI 0.12–0.17)). This review provides comprehensive information on the prognosis of IPF, which can inform treatment discussions with patients and comparisons for future studies with new therapies.

Without anti-fibrotic therapy, patients with IPF have a mortality rate of 31% at ≥5 years, and a mean overall survival of 4 years over 10 years of follow-uphttp://bit.ly/2SDiZSb

Implementation of a hepatitis B screening process prior to CD20 therapy treatment in an oncology practice

287

Background: Reactivation of hepatitis B virus (HBV) during or after chemotherapy is a serious complication of cancer treatment. Guidelines suggest hepatitis B testing prior to the initiation of CD20 based therapies. Black box warnings mandate clinicians screen patients for HBV before starting immunosuppressive therapy due to the risk of hepatitis B reactivation. We conducted a workflow implementation change at our infusion center sites to improve hepatitis B serological testing in patients receiving CD20 agents at our cancer center. Methods: For baseline evaluation, patients at The University of Arizona Cancer Center who were treated with CD20 agents between the years 2013 to April 2014 were retrospectively evaluated for HBV serology results prior to the initiation of first treatment. We implemented a pharmacy and nursing workflow process regarding chemotherapy orders and lab testing through the integrated EMR technology. Presence of Hepatitis B Surface Antigen (HBsAg) and Hepatitis B Core Antibody (HBcAb) were considered complete; absence of all 2 was ‘not done’ with remaining being incomplete. We focused on improving our screening process during our analysis post-intervention from April 2014 to November 2017. Results: In our baseline study, 35% (n = 17) out of 48 patients had been tested for hepatitis B for hematologic malignancies. Post-implementation yielded 89 patients with 63 lymphoma patients, and 11 leukemia and 15 other hematological-associated diagnosis. Ninety one percent (n = 81) had been tested post-implementation for Hepatitis B labs prior to starting CD20 treatment. No Hepatitis B reactivation was identified in either study arms. Conclusions: Prior to implementation less than 35% of our patients were tested and our implementation process more than doubled our testing percentages to 91%. This process allows for an integrated workflow between pharmacy and nursing to mitigate required lab testing for CD20 agents in hematologic malignancies. The utilization of this workflow process is now being implemented with other CD20 agents for non-oncologic diagnosis.

ENL: structure, function, and roles in hematopoiesis and acute myeloid leukemia

ENL/MLLT1 is a distinctive member of the KMT2 family based on its structural homology. ENL is a histone acetylation reader and a critical component of the super elongation complex. ENL plays pivotal roles in the regulation of chromatin remodelling and gene expression of many important proto-oncogenes, such as Myc, Hox genes, via histone acetylation. Novel insights of the key role of the YEATS domain of ENL in the transcriptional control of leukemogenic gene expression has emerged from whole genome Crisp-cas9 studies in acute myeloid leukemia (AML). In this review, we have summarized what is currently known about the structure and function of the ENL molecule. We described the ENL's role in normal hematopoiesis, and leukemogenesis. We have also outlined the detailed molecular mechanisms underlying the regulation of target gene expression by ENL, as well as its major interacting partners and complexes involved. Finally, we discuss the emerging knowledge of different approaches for the validation of ENL as a therapeutic target and the development of small-molecule inhibitors disrupting the YEATS reader pocket of ENL protein, which holds great promise for the treatment of AML. This review will not only provide a fundamental understanding of the structure and function of ENL and update on the roles of ENL in AML, but also the development of new therapeutic strategies.

NF-κB promotes the stem-like properties of leukemia cells by activation of LIN28B

AIM

To examine whether nuclear factor kappa B (NF-κB) activity regulates LIN28B expression and their roles in leukemia stem cell (LSC)-like properties.

METHODS

We used pharmacological inhibitor and cell viability assays to examine the relation between NF-κB and LIN28B. Western blot and qRT-PCR was employed to determine their protein and mRNA levels. Luciferase reporter was constructed and applied to explore the transcriptional regulation of LIN28B. We manipulated LIN28B level in acute myeloid leukemia (AML) cells and investigated LSC-like properties with colony forming and serial replating assays.

RESULTS

This study revealed the relationship between NF-κB and LIN28B in AML cells through drug inhibition and overexpression experiments. Notably, inhibition of NF-κB by pharmacological inhibitors reduced LIN28B expression and decreased cell proliferation. We demonstrated that NF-κB binds to the -819 to -811 region of LIN28B promoter, and transcriptionally regulates LIN28B expression. LIN28B protein was significantly elevated in NFκB1 transfected cells compared to vector control. Importantly, ectopic expression of LIN28B partially rescued the self-renewal capacity impaired by pharmacological inhibition of NF-κB activity.

CONCLUSION

These results uncover a regulatory signaling, NF-κB/LIN28B, which plays a pivotal role in leukemia stem cell-like properties and it could serve as a promising intervening target for effective treatment of AML disease.

Identification of a novel ligand for the ATAD2 bromodomain with selectivity over BRD4 through a fragment growing approach

ATAD2 is an ATPase that is overexpressed in a variety of cancers and associated with a poor patient prognosis. This protein has been suggested to function as a cofactor for a range of transcription factors, including the proto-oncogene MYC and the androgen receptor. ATAD2 comprises an ATPase domain, implicated in chromatin remodelling, and a bromodomain which allows it to interact with acetylated histone tails. Dissection of the functional roles of these two domains would benefit from the availability of selective, cell-permeable pharmacological probes. An in silico evaluation of the 3D structures of various bromodomains suggested that developing small molecule ligands for the bromodomain of ATAD2 is likely to be challenging, although recent reports have shown that ATAD2 bromodomain ligands can be identified. We report a structure-guided fragment-based approach to identify lead compounds for ATAD2 bromodomain inhibitor development. Our findings indicate that the ATAD2 bromodomain can accommodate fragment hits (Mr < 200) that yield productive structure-activity relationships, and structure-guided design enabled the introduction of selectivity over BRD4.

Oxygen Desaturation Index Differs Significantly Between Types of Sleep Software

STUDY OBJECTIVES

The aim of this study was to compare the oxygen desaturation index (ODI) generated by two different sleep software systems.

METHODS

Participants undergoing diagnostic polysomnography for suspected obstructive sleep apnea underwent simultaneous oximetry recording using the ResMed ApneaLink Plus device (AL) and Compumedics Profusion PSG3 system (Comp). The ODI was calculated by the algorithms in the respective software of each system. To determine if differences were due to algorithm or recording devices, the Comp software was also used to generate ODI values using oximetry data from the AL.

RESULTS

In 106 participants, there was good correlation but poor agreement in the ODI generated by the two systems. AL ODI values tended to be higher than Comp ODI values, but with significant variability. For ODI4%, bias was 4.4 events/h (95% limits of agreement -5.8 to 14.6 events/h). There was excellent correlation and agreement when the same oximetry raw data was analyzed by both systems. For ODI4%, bias was 0.03 events/h (95% limits of agreement -2.7 to 2.8 events/h). Similar results were evident when the ODI3% was used.

CONCLUSIONS

There is a clinically significant difference in ODI values generated by the two systems, likely due to device signal processing, rather than difference in ODI calculation algorithms.

Malignant metastatic deposits in an immunocompromised patient—could this be tuberculosis?

We report the case of a 50-year-old female renal transplant patient who developed disseminated deposits initially diagnosed as metastatic malignancy of unknown primary. She declined a tissue diagnosis but subsequently developed recurrent sepsis and symptomatic unilateral pleural effusion. Mycobacterium tuberculosis was cultured from pleural fluid. Following introduction of anti-tuberculous medications, her symptoms improved rapidly and the progression of her disseminated deposits stabilized. Tuberculosis is well-known to be associated with immunocompromised patients. It is a curable disease and should remain an important differential diagnosis for transplant patients who develop suspicious malignant metastatic lesions.

HOXC10 suppresses browning of white adipose tissues

Given that increased thermogenesis in white adipose tissue, also known as browning, promotes energy expenditure, significant efforts have been invested to determine the molecular factors involved in this process. Here we show that HOXC10, a homeobox domain-containing transcription factor expressed in subcutaneous white adipose tissue, is a suppressor of genes involved in browning white adipose tissue. Ectopic expression of HOXC10 in adipocytes suppresses brown fat genes, whereas the depletion of HOXC10 in adipocytes and myoblasts increases the expression of brown fat genes. The protein level of HOXC10 inversely correlates with brown fat genes in subcutaneous white adipose tissue of cold-exposed mice. Expression of HOXC10 in mice suppresses cold-induced browning in subcutaneous white adipose tissue and abolishes the beneficial effect of cold exposure on glucose clearance. HOXC10 exerts its effect, at least in part, by suppressing PRDM16 expression. The results support that HOXC10 is a key negative regulator of the process of browning in white adipose tissue.

Selective insulin resistance in adipocytes

Aside from glucose metabolism, insulin regulates a variety of pathways in peripheral tissues. Under insulin-resistant conditions, it is well known that insulin-stimulated glucose uptake is impaired, and many studies attribute this to a defect in Akt signaling. Here we make use of several insulin resistance models, including insulin-resistant 3T3-L1 adipocytes and fat explants prepared from high fat-fed C57BL/6J and ob/ob mice, to comprehensively distinguish defective from unaffected aspects of insulin signaling and its downstream consequences in adipocytes. Defective regulation of glucose uptake was observed in all models of insulin resistance, whereas other major actions of insulin such as protein synthesis and anti-lipolysis were normal. This defect corresponded to a reduction in the maximum response to insulin. The pattern of change observed for phosphorylation in the Akt pathway was inconsistent with a simple defect at the level of Akt. The only Akt substrate that showed consistently reduced phosphorylation was the RabGAP AS160 that regulates GLUT4 translocation. We conclude that insulin resistance in adipose tissue is highly selective for glucose metabolism and likely involves a defect in one of the components regulating GLUT4 translocation to the cell surface in response to insulin.

Health promotion board-ministry of health clinical practice guidelines: treating tobacco use and dependence

The Health Promotion Board (HPB) has updated the clinical practice guidelines on Treating Tobacco Use and Dependence to provide health professionals in Singapore with evidence-based interventions for smoking cessation. This article reproduces the introduction and executive summary of key guideline recommendations (with recommendations from the guidelines) from the HPB-MOH Clinical Practice Guidelines on Treating Tobacco Use and Dependence, for the information of SMJ readers. Chapters and page numbers mentioned in the reproduced extract refer to the full text of the guidelines, which are available from the Health Promotion Board website: http://www.hpb.gov.sg/cpg-smoking-cessation. The recommendations should be used with reference to the full text of the guidelines. Following this article are multiple choice questions based on the full text of the guidelines.

Impaired Akt phosphorylation in insulin-resistant human muscle is accompanied by selective and heterogeneous downstream defects

AIMS/HYPOTHESIS

Muscle insulin resistance, one of the earliest defects associated with type 2 diabetes, involves changes in the phosphoinositide 3-kinase/Akt network. The relative contribution of obesity vs insulin resistance to perturbations in this pathway is poorly understood.

METHODS

We used phosphospecific antibodies against targets in the Akt signalling network to study insulin action in muscle from lean, overweight/obese and type 2 diabetic individuals before and during a hyperinsulinaemic-euglycaemic clamp.

RESULTS

Insulin-stimulated Akt phosphorylation at Thr309 and Ser474 was highly correlated with whole-body insulin sensitivity. In contrast, impaired phosphorylation of Akt substrate of 160 kDa (AS160; also known as TBC1D4) was associated with adiposity, but not insulin sensitivity. Neither insulin sensitivity nor obesity was associated with defective insulin-dependent phosphorylation of forkhead box O (FOXO) transcription factor. In view of the resultant basal hyperinsulinaemia, we predicted that this selective response within the Akt pathway might lead to hyperactivation of those processes that were spared. Indeed, the expression of genes targeted by FOXO was downregulated in insulin-resistant individuals.

CONCLUSIONS/INTERPRETATION

These results highlight non-linearity in Akt signalling and suggest that: (1) the pathway from Akt to glucose transport is complex; and (2) pathways, particularly FOXO, that are not insulin-resistant, are likely to be hyperactivated in response to hyperinsulinaemia. This facet of Akt signalling may contribute to multiple features of the metabolic syndrome.

Novel systems for dynamically assessing insulin action in live cells reveals heterogeneity in the insulin response

Regulated GLUT4 trafficking is a key action of insulin. Quantitative stepwise analysis of this process provides a powerful tool for pinpointing regulatory nodes that contribute to insulin regulation and insulin resistance. We describe a novel GLUT4 construct and workflow for the streamlined dissection of GLUT4 trafficking; from simple high throughput screens to high resolution analyses of individual vesicles. We reveal single cell heterogeneity in insulin action highlighting the utility of this approach - each cell displayed a unique and highly reproducible insulin response, implying that each cell is hard-wired to produce a specific output in response to a given stimulus. These data highlight that the response of a cell population to insulin is underpinned by extensive heterogeneity at the single cell level. This heterogeneity is pre-programmed within each cell and is not the result of intracellular stochastic events.

Leaving the paediatric emergency department without being seen: understanding the patient and the risks

AIM

The aim of this study is to examine the left-without-being-seen (LWBS) patient population of a tertiary paediatric emergency department (ED) to provide quality assurance and risk management data.

METHODS

This is a prospective observational study of patients who LWBS after presenting to the Royal Children's Hospital Melbourne ED between July and November 2005. Information was collected from electronic databases and follow-up telephone interviews performed by the principal investigator 3-5 days after the presentation.

RESULTS

Over the 17-week study period, 7.6% of attendances were recorded as having LWBS. These patients and their presentations resembled the general ED population in many respects. However, there were several significant differences, particularly in relation to age, insurance status, mode of arrival, referral status, arrival time and illness severity. Most families (74%) indicated they would have been equally happy to visit a general practitioner instead had one been available. Prolonged waiting times and recognition that their child's illness was not severe were the most frequent reasons for leaving. Most parents subsequently accessed alternate health care or were planning to do so, and the majority stated their child's illness was improving. Parents maintained a surprisingly positive attitude to their ED presentation.

CONCLUSION

The individual risks associated with leaving the ED before a child has been medically assessed are small. However, when multiplied several thousandfold as a function of the frequency of LWBS patients, the chance of serious adverse events becomes real. Potential risk management strategies include decreasing absolute LWBS numbers by addressing ED overcrowding and providing alternate sources for non-urgent care.

Amplification and demultiplexing in insulin-regulated Akt protein kinase pathway in adipocytes

Akt plays a major role in insulin regulation of metabolism in muscle, fat, and liver. Here, we show that in 3T3-L1 adipocytes, Akt operates optimally over a limited dynamic range. This indicates that Akt is a highly sensitive amplification step in the pathway. With robust insulin stimulation, substantial changes in Akt phosphorylation using either pharmacologic or genetic manipulations had relatively little effect on Akt activity. By integrating these data we observed that half-maximal Akt activity was achieved at a threshold level of Akt phosphorylation corresponding to 5–22% of its full dynamic range. This behavior was also associated with lack of concordance or demultiplexing in the behavior of downstream components. Most notably, FoxO1 phosphorylation was more sensitive to insulin and did not exhibit a change in its rate of phosphorylation between 1 and 100 nm insulin compared with other substrates (AS160, TSC2, GSK3). Similar differences were observed between various insulin-regulated pathways such as GLUT4 translocation and protein synthesis. These data indicate that Akt itself is a major amplification switch in the insulin signaling pathway and that features of the pathway enable the insulin signal to be split or demultiplexed into discrete outputs. This has important implications for the role of this pathway in disease.

Role of genetic testing in retinoblastoma management at a tertiary referral centre

BACKGROUND

Retinoblastoma (MIM +180 200) is a malignant neoplasm affecting embryonal retina, associated with mutations in the RB1 gene. This paper investigates the results of RB1 testing in retinoblastoma management in a tertiary referral centre.

METHODS

A retrospective audit of genetic testing for retinoblastoma from 2003 to 2008, to determine epidemiology, rate of mutation detection and spectrum was undertaken. Eligible probands were identified from the department database and hospital records examined. DNA extracted from tumour tissue and/or peripheral blood was analysed. All patients and families underwent genetic counselling.

RESULTS

Twenty patients, including one family, were identified. Eight had bilateral tumours, of whom seven presented before 2 years of age, whereas 10 of 12 unilateral cases presented after 2 years of age. Ten patients (50%) were European, four Maori (20%), three Pacific (15%), two Asian (10%), and one of mixed ancestry (5%). Genetic analysis achieved mutation detection on all affected alleles of all the patients, with tumour tissue available for testing in 19 cases. Ten (40%) had germline mutations (eight bilateral and two unilateral), including one mosaic. 75% of affected Maori had germline mutations compared with 40% Europeans. A wide range of mutations was detected with one novel mutation identified in a familial case.

CONCLUSION

Advances in gene testing have enabled a high rate of mutation detection, particularly when tumour tissue is genotyped. Genetic analysis is integral to the management of retinoblastoma patients allowing enhanced follow-up care, avoidance of unnecessary examinations, family screening, counselling and reproductive planning, with early tumour detection in predisposed individuals.

Dissecting the mechanism of insulin resistance using a novel heterodimerization strategy to activate Akt

Insulin resistance can occur in response to many different external insults, including chronic exposure to insulin itself as well as other agonists such as dexamethasone. It is generally thought that such defects arise due to a defect(s) at an early stage in the insulin signaling cascade. One model suggests that this involves activation of the mammalian target of rapamycin/S6 kinase pathway, which inactivates insulin receptor substrate via Ser/Thr phosphorylation. However, we have recently shown that insulin receptor substrate is not a major node for insulin resistance defects. To explore the mechanism of insulin resistance, we have developed a novel system to activate Akt independently of its upstream effectors as well as other insulin-responsive pathways such as mitogen-activated protein kinase. 3T3-L1 adipocytes were rendered insulin-resistant either with chronic insulin or dexamethasone treatment, but conditional activation of Akt2 stimulated hemagglutinin-tagged glucose transporter 4 translocation to the same extent in these insulin-resistant and control cells. However, addition of insulin to cells in which Akt was conditionally activated resulted in a reversion to the insulin-resistant state, indicating a feedforward inhibitory mechanism activated by insulin itself. This effect was overcome with wortmannin, implicating a role for phosphatidylinositol 3-kinase in this inhibitory process. We conclude that in chronic insulin- and dexamethasone-treated cells, acute activation with insulin itself is required to activate a feedforward inhibitory pathway likely emanating from phosphatidylinositol 3-kinase that converges on a target downstream of Akt to cause insulin resistance.

Cluster analysis of insulin action in adipocytes reveals a key role for Akt at the plasma membrane

The phosphatidylinositol 3-kinase/Akt pathway regulates many biological processes, including insulin-regulated GLUT4 insertion into the plasma membrane. However, Akt operates well below its capacity to facilitate maximal GLUT4 translocation. Thus, reconciling modest changes in Akt expression or activity as a cause of metabolic dysfunction is complex. To resolve this, we examined insulin regulation of components within the signaling cascade in a quantitative kinetic and dose-response study combined with hierarchical cluster analysis. This revealed a strong relationship between phosphorylation of Akt substrates and GLUT4 translocation but not whole cell Akt phosphorylation. In contrast, Akt activity at the plasma membrane strongly correlated with GLUT4 translocation and Akt substrate phosphorylation. Additionally, two of the phosphorylated sites in the Akt substrate AS160 clustered separately, with Thr(P)-642 grouped with other Akt substrates. Further experiments suggested that atypical protein kinase Czeta phosphorylates AS160 at Ser-588 and that these two sites are mutually exclusive. These data indicate the utility of hierarchical cluster analysis for identifying functionally related biological nodes and highlight the importance of subcellular partitioning of key signaling components for biological specificity.

Identification of a distal GLUT4 trafficking event controlled by actin polymerization

The insulin-stimulated trafficking of GLUT4 to the plasma membrane in muscle and fat tissue constitutes a central process in blood glucose homeostasis. The tethering, docking, and fusion of GLUT4 vesicles with the plasma membrane (PM) represent the most distal steps in this pathway and have been recently shown to be key targets of insulin action. However, it remains unclear how insulin influences these processes to promote the insertion of the glucose transporter into the PM. In this study we have identified a previously uncharacterized role for cortical actin in the distal trafficking of GLUT4. Using high-frequency total internal reflection fluorescence microscopy (TIRFM) imaging, we show that insulin increases actin polymerization near the PM and that disruption of this process inhibited GLUT4 exocytosis. Using TIRFM in combination with probes that could distinguish between vesicle transport and fusion, we found that defective actin remodeling was accompanied by normal insulin-regulated accumulation of GLUT4 vesicles close to the PM, but the final exocytotic fusion step was impaired. These data clearly resolve multiple steps of the final stages of GLUT4 trafficking, demonstrating a crucial role for actin in the final stage of this process.

Development of an immortalised, post-pubertal gonadotrophin-releasing hormone neuronal cell line

Gonadotrophin-releasing hormone (GnRH) is important in reproduction, although some of the mechanisms for its synthesis and release remain elusive. Progress in understanding the GnRH neurone has been hampered by the limited number and diffuse distribution of the neurone in the mammalian brain. Several stable GnRH-expressing cell lines have been developed using in vivo expression of the simian virus 40 T Antigen (TAg), and they have been helpful for the study of gene expression and neuronal function. However, expression of an immortalising gene may interfere with normal cellular function. We developed a novel GnRH-secreting cell line transgenic mouse model suitable for targeted transformation in post-pubertal mice using a tetracycline-regulated TAg transgene. This clonal cell line, GRT, expresses neuronal markers and GnRH. GRT cells grown in medium containing tetracycline-free serum express increasing mRNA levels of GnRH associated with declining levels of TAg expression. The novelty and ultimately the usefulness of this cell line is that TAg expression, which could affect the GnRH neuronal phenotype, can be regulated by tetracycline.

Skin wound closure with a novel shape-memory alloy fixator

BACKGROUND

Previously, we have described novel, thermally deployable tissue fixators based on the shape-memory properties of nickel titanium. The present study reports on the in vivo wound closure with these fixators as a preliminary to evaluating their use for bowel anastomoses.

METHODS

Twenty adult Sprague-Dawley rats had 2.0-cm dorsal skin incisions approximated either with shape-memory alloy (SMA) fixators or conventional skin staples on a random basis. Electrical resistance heating was used to transform and deploy the SMA fixators into the wound. The rats were killed on day 14 or day 28 and wound specimens were harvested for force distraction studies and histologic examination.

RESULTS

There was no incidence of wound dehiscence. 14- and 28-day wounds from both groups showed no significant difference in breaking force or energy. Histology revealed appropriate stages of wound healing for both SMA-closed and control wounds.

CONCLUSIONS

The results confirm the efficacy and safety of tissue-edge approximation with SMA fixators.

PCR identification and automated ribotyping of Pseudomonas aeruginosa clinical isolates from intensive care patients

Nosocomial isolates of Pseudomonas aeruginosa exhibit high rates of resistance to antibiotics, and are often multidrug resistant. P. aeruginosa clinical isolates (n = 56) were obtained from ICU patients in a hospital in Pakistan over a 3-y period. Antimicrobial susceptibility of the 56 P. aeruginosa clinical isolates was investigated using 7 antibiotics and the resistance rates were as follows: aztreonam (68% resistant), ceftazidime (67%), imipenem (66%), ofloxacin (59%), amikacin (56%), gentamicin (44%), and piperacillin-tazobactam (27%) (p < 0.01). In addition, 55% of the P. aeruginosa clinical isolates were resistant to 4 or more antibiotics. Imipenem-resistant strains were frequently associated with ceftazidime, ofloxacin, aztreonam, and more strikingly, amikacin resistance (p < 0.05). PCR (using P. aeruginosa-specific primers VIC1 + VIC2 and P1 + P2, respectively) was highly specific and sensitive, and was positive for all 56 P. aeruginosa isolates tested. Automated ribotyping was used to investigate the clonal diversity of the 56 P. aeruginosa isolates. Automated ribotyping indicated that the clinical isolates were clonally related and could be clustered into 4 major ribogroups based on their similarity index, with ribogroup II being the dominant one. The P. aeruginosa isolates in ribogroup II were correlated with their antibiotic resistance pattern and, interestingly, there seemed to be a gradual acquisition of multiple antibiotic resistance associated with the isolates within this group over time. The ribotyping data, together with the antibiotic resistance profile, provide valuable molecular epidemiology information for the control of hospital-acquired P. aeruginosa infections.

Expression of the human myotonic dystrophy kinase-related Cdc42-binding kinase gamma is regulated by promoter DNA methylation and Sp1 binding

Myotonic dystrophy kinase-related Cdc42 binding kinases (MRCKs) are family members most related to the myotonic dystrophy kinase (DMPK), RhoA-binding kinase (ROK), and citron kinase. Two highly conserved members, MRCKalpha and -beta, have been previously identified and characterized. We now describe a novel isoform, MRCKgamma, which is functionally and structurally related to members of this kinase family. We show these kinases to have marked similarities in their genomic organization, substrate phosphorylation, and catalytic autoinhibition. Unlike MRCKalpha and -beta, which are expressed ubiquitously, MRCKgamma mRNA was only expressed in heart and skeletal muscle. In cultured cells, MRCKgamma showed differential expression with high levels of expression only in certain cell lines. DNA analysis showed that lack of expression is correlated with promoter DNA methylation. We have mapped the methylation sites in the MRCKgamma promoter. Significantly, agents that suppressed DNA methylation caused increases in the expression of the kinase in low-expressing cells, further supporting the notion that promoter DNA methylation plays an important role in the expression of MRCKgamma. Analysis of the MRCKgamma promoter has also revealed two proximal Sp1 sites that are essential for transcriptional activity. We conclude that both promoter DNA methylation and Sp1 binding are important regulators for MRCKgamma expression.

Therapeutic and reproductive cloning--implications and recommendations

The announcement of Dolly's birth took the world by storm, mainly because what was thought impossible has become possible. Optimism that new approaches in agriculture and medicine abound, as much as fear and imagination leading to Frankenstein-like scenarios. Scientifically, cloning refers to replicating an animal with the same nuclear genetic material; whilst it may refer to embryos as the source material, the current storm refers to differentiated ("somatic") cells. Cloning technology is useful in the following areas: agriculture, to produce animals of superior or specific qualities; endangered animals, to increase genetic diversity through widening the gene pool; understanding fundamental questions in developmental embryology, through the use of laboratory animals; and in human therapy, to produce cells and possibly tissues for repair and regeneration. In the first 2 instances, it is reproductive cloning. In the last instance, it is therapeutic cloning, as no individuals are "produced". Human reproductive cloning is not allowed by all governments that have deliberated on it, and therapeutic cloning is allowed by some under certain circumstances. As therapeutic cloning has great potential in cures of many diseases, it should be allowed but with safeguards to prevent abuse and reproductive cloning in the human.

p80 ROKalpha binding protein is a novel splice variant of CRMP-1 which associates with CRMP-2 and modulates RhoA-induced neuronal morphology

Using antibody against the Rho binding domain of ROKalpha, two neuronal phosphoproteins of 62 and 80 kDa were co-immunoprecipitated from brain extracts. Peptide analysis revealed their identity as collapsin response mediator proteins (CRMPs); p62 was CRMP-2 whereas p80 was a novel splice form of CRMP-1 with an extended N-terminus. p80 CRMP-1 was able to complex with CRMP-2, suggesting that p80 CRMP-1 and CRMP-2 form oligomers. CRMP-2 was the major substrate of ROK. p80 CRMP-1 interacted with the kinase domain of ROKalpha, resulting in inhibition of the catalytic activity towards other substrates. Over-expression of p80 CRMP-1 and CRMP-2 together counteracted the effects of RhoA on neurite retraction, an effect enhanced by mutation of the ROK phosphorylation site in CRMP-2. p80 CRMP-1 and CRMP-2 may be modulators of RhoA-dependent signaling, through interaction with and regulation of ROKalpha.

Immigration and economic welfare: resource and environmental aspects

"The relation between immigration and the economic welfare of residents is analyzed for resource-rich economies (such as Australia) both under competitive conditions and when various distortions are present. Immigration provides efficiency gains for residents under distortion-free competition for standard 'gains from trade' reasons. Such reasons, however, tend to be ignored by immigration and 'optimal population' theorists who raise the issue of restricting immigration without explicitly referring to the distortions. In situations where distortions and externalities are present, we argue that it is generally preferable to devise policies which specifically target the distortions than to restrict immigration."

The evolution and outcome of cavitating periventricular leukomalacia in infancy. A study of 46 cases

Forty six infants with the ultrasonic diagnosis of cavitating periventricular leukomalacia (CPVL) have been reviewed. Follow up examination results allow correlation between the ultrasound appearances and subsequent neurodevelopmental and neurological deficits. The highest incidence of this condition was found in infants at and below 27 weeks gestation, and occurred in 15% of very premature infants surviving 14 days or more. Cavities developed 15 days after the onset of periventricular echodensity (median time). Ventricular dilatation occurred in 24% of the infants who developed cavities. Follow up information was available in 27 infants and 18 of these (67%) had significant neurodevelopmental handicap. The location of echolucent cavities were described as involving anterior, middle or posterior cerebral zones or any combination of these. Cerebral palsy was closely related to the presence of cavities, but there was little association between cavities and developmental delay. Four factors were found to predict cerebral palsy: cavities within the occipital zone, the involvement of multiple regions of the brain, lesions greater than 1 cm in diameter and cavities associated with subcortical leukomalacia. Lesions confined to the anterior or middle zones were unlikely to be associated with significant handicap. The presence of cavities per se was not associated with a higher incidence of severe developmental delay.