Multifaceted impairments in impulsivity and brain structural abnormalities in opioid dependence and abstinence

This study was part funded by an unrestricted educational grant provided by Schering-Plough, a grant by an anonymous trust and the Scottish Mental Health Research Network.Background: Chronic opioid exposure, as a treatment for a variety of disorders or as drug of misuse, is common worldwide, but behavioural and brain abnormalities remain under-investigated. Only a small percentage of patients who receive methadone maintenance treatment (MMT) for previous heroin misuse eventually achieve abstinence and studies on such patients are rare. Method: The Cambridge Neuropsychological Test Automated Battery and T1 weighted magnetic resonance imaging (MRI) were used to study a cohort of 122 male individuals: a clinically stable opioid-dependent patient group receiving MMT (n = 48), an abstinent previously MMT maintained group (ABS) (n = 24) and healthy controls (n = 50). Results: Stable MMT participants deliberated longer and placed higher bets earlier in the Cambridge Gambling Task (CGT) and showed impaired strategic planning compared with healthy controls. In contrast, ABS participants showed impairment in choosing the least likely outcome, delay aversion and risk adjustment on the CGT, and exhibited non-planning impulsivity compared with controls. MMT patients had widespread grey matter reductions in the orbitomedial prefrontal cortex, caudate, putamen and globus pallidus. In contrast, ABS participants showed midbrain–thalamic grey matter reductions. A higher methadone dose at the time of scanning was associated with a smaller globus pallidus in the MMT group. Conclusions: Our findings support an interpretation of heightened impulsivity in patients receiving MMT. Widespread structural brain abnormalities in the MMT group and reduced brain structural abnormality with abstinence suggest benefit of cessation of methadone intake. We suggest that a longitudinal study is required to determine whether abstinence improves abnormalities, or patients who achieve abstinence have reduced abnormalities before methadone cessation.Publisher PDFPeer reviewe

Microscopic Mechanism of Specific Peptide Adhesion to Semiconductor Substrates

The design of hybrid peptide-solid interfaces for nanotechnological applications such as biomolecular nanoarrays requires a deep understanding of the basic mechanisms of peptide binding and assembly at solid substrates. Here we show by means of experimental and computational analyses that the adsorption properties of mutated synthetic peptides at semiconductors exhibit a clear sequence-dependent adhesion specificity. Our simulations of a novel hybrid peptide-substrate model reveal the correspondence between proline mutation and binding affinity to a clean silicon substrate. After synthesizing theoretically suggested amino-acid sequences with different binding behavior, we confirm the relevance of the selective mutations upon adhesion in our subsequent atomic force microscopy experiments.Comment: 14 pages, 4 figure

The Nielsen Identities for the Two-Point Functions of QED and QCD

We consider the Nielsen identities for the two-point functions of full QCD and QED in the class of Lorentz gauges. For pedagogical reasons the identities are first derived in QED to demonstrate the gauge independence of the photon self-energy, and of the electron mass shell. In QCD we derive the general identity and hence the identities for the quark, gluon and ghost propagators. The explicit contributions to the gluon and ghost identities are calculated to one-loop order, and then we show that the quark identity requires that in on-shell schemes the quark mass renormalisation must be gauge independent. Furthermore, we obtain formal solutions for the gluon self-energy and ghost propagator in terms of the gauge dependence of other, independent Green functions.Comment: 25 pages, plain TeX, 4 figures available upon request, MZ-TH/94-0

Examining usage behavior of a goal-supporting mHealth app in primary care among patients with multiple chronic conditions:A qualitative study

BACKGROUND: Although mobile health (mHealth) apps are increasingly being used to support patients with multiple chronic conditions (multimorbidity), most mHealth apps experience low interaction and eventual abandonment. To tackle this engagement issue, when developing an mHealth program, it is important to understand the social-behavioral factors that affect patients’ use behavior. OBJECTIVE: The aim of this study was to explore the social and behavioral factors contributing to patients’ use behavior of an mHealth app called the electronic Patient-Reported Outcome (ePRO). The ePRO app supports goal-oriented care delivery in interdisciplinary primary care models. METHODS: A descriptive qualitative study was used to analyze interview data collected for a larger mixed methods pragmatic trial. The original 15-month trial was conducted in 6 primary care teams across Ontario, Canada, between 2018 and 2019. The eligibility criteria for patients were being aged ≥60 years with ≥10 visits within the previous 12 months of study enrollment. For this analysis, patients were classified as long-term or short-term users based on their length of use of the ePRO app during the trial. The Social Cognitive Theory by Bandura was used to categorize social-behavioral factors that contributed to patients’ decision to continue or discontinue using the app. RESULTS: The patient-provider relationship emerged as a key factor that shaped patients’ experiences with the app and subsequent decision to continue using the app. Other factors that contributed to patients’ decision to continue using the app were personal and social circumstances, perceived usefulness, patients’ previous experience with goal-related behaviors, and confidence in one’s capability. There was an overlap of experience between long- and short-term app users but, in general, long-term users perceived the app to be more useful and their goals to be more meaningful than short-term app users. This observation was complicated by the fact that patient health-related goals were dynamic and changed over time. CONCLUSIONS: Complex patients’ use behavior of a goal-supporting mHealth app is shaped by an array of sociobehavioral factors that can evolve. To tackle this dynamism, there should be an emphasis on creating adaptable health technologies that are easily customizable by patients and able to respond to their changing contexts and needs. TRIAL REGISTRATION: ClinicalTrials.gov NCT02917954; https://clinicaltrials.gov/ct2/show/NCT0291795

Mapping for Conceptual Clarity: Exploring Implementation of Integrated Community-Based Primary Health Care from a Whole Systems Perspective.

Published source must be acknowledged with citationIntroduction: Studying implementation of integrated models of community-based primary health care requires a "whole systems" multidisciplinary approach to capture micro, meso and macro factors. However, there is, as yet, no clear operationalization of a "whole systems" approach to guide multidisciplinary research programs. Theoretical frameworks and approaches from diverse academic traditions specify different aspects of the health system in more depth. Enabling analysis across the system, when data and ideas are captured using different taxonomies, requires that we map terms and constructs across the models. Theory and methods: This paper uses concept mapping techniques to compare and contrast the theoretical frameworks and approaches used in the iCOACH project including: Ham's Ten Characteristics of the High-Performing Chronic Care System (capturing patient/carer and provider perspectives), the Organizational Context and Capabilities for Integrating Care framework (capturing the organizational perspective), and the Health Policy Monitor framework (capturing the policy system perspective). The aim of the paper is to link concepts across different theoretical framework to guide the iCOACH study. Results: A concept map was developed that identifies 8 overarching concepts across the heuristic models. A preliminary analysis of one of these overarching concepts, care coordination, demonstrates how different perspectives will assign different meanings, values, and drivers of seemingly similar ideas. For patients and carers care coordination is about having a responsive team of health care providers. Building relationships in teams that exist within and across different organizations is essential for providers to achieve care coordination, where managers and policy makers see care coordination as being more about creating linkages and addressing systems gaps. Discussion and conclusion: This work represents a first step towards development of a fully formed conceptual framework that includes key domains, concepts, and mechanisms of implementing integrated community-based primary health care.Published onlin

Observational study investigating tooth extraction and the shortened dental arch approach

The shortened dental arch (SDA ) provides a cost‐effective dentition, considering the population is ageing and retaining teeth for longer. The aims were to observe the reasons and sites of tooth extraction and assess the functional dentition over 15 years in dental practice. Subjects were recruited who required permanent tooth extractions between 2000 and 2015. The reasons for extractions were chosen from twelve extraction codes. Data were also collected for demographics, tooth position, root treated teeth and functional pairs remaining. Patient‐centred factors on reasons for tooth extraction and comments on chewing ability and aesthetics following extractions were recorded. Nine hundred and fifty‐one teeth were extracted in 900 patients. The mean age was 60 years (SD 20, SE 7, 95% CI 46, 74). Reasons for extraction were periodontal disease (n = 361, 38%), periapical infection (n = 288, 34%) or tooth and tooth‐root fractures (15%). Extractions included 201 (21%) second molars, 179 (19%) first molars, 152 (16%) second premolars, 95 (10%) first incisors, 86 (9%) second incisors, 76 (8%) canines and 67 (7%) first premolars. Following extractions, median functional pairs were 12, interquartile range (IQR ) 19–7. Individuals with ≥10 functional pairs including anterior teeth (60%, n = 571) had no complaints with chewing ability or aesthetics. They did not require additional prostheses. Periodontal disease and periapical infection were the main causes for the extraction. First and second molars followed by second premolars were the most commonly extracted teeth. This study supports the SDA in creating a cost effective, functional dentition in an aging population, provided remaining teeth and restorations are preserved/maintained, oral health is promoted, and anterior aesthetic tooth replacement is ensured