Development and validation of a new measurement instrument to assess internship experience of medical doctors in low-income and middle-income countries

Routine surveys are used to understand the training quality and experiences of junior doctors but there are lack of tools designed to evaluate the training experiences of interns in low-income and middle-income countries (LMICs) where working conditions and resource constraints are challenging. We describe our process developing and validating a 'medical internship experience scale' to address this gap, work involving nine LMICs that varied in geographical locations, income-level and internship training models. We used a scoping review of existing tools, content validity discussions with target populations and an expert panel, back-and-forth translations into four language versions and cognitive interviews to develop and test the tool. Using data collected from 1646 interns and junior medical doctors, we assessed factor structure and assessed its reliability and validity. Fifty items about experiences of medical internship were retained from an initial pool of 102 items. These 50 items represent 6 major factors (constructs): (1) clinical learning and supervision, (2) patient safety, (3) job satisfaction, (4) stress and burnout, (5) mental well-being, and (6) fairness and discrimination. We reflect on the process of multicountry scale development and highlight some considerations for others who may use our scale, using preliminary analyses of the 1646 responses to illustrate that the tool may produce useful data to identify priorities for action. We suggest this tool could enable LMICs to assess key metrics regarding intern straining and initial work experiences and possibly allow comparison across countries and over time, to inform better internship planning and management.

Experimental evaluation of biological regeneration of arable soil: The effects of grass-clover leys and arbuscular mycorrhizal inoculants on wheat growth, yield, and shoot pathology

Wheat yields have plateaued in the UK over the last 25 years, during which time most arable land has been annually cropped continuously with short rotations dominated by cereals. Arable intensification has depleted soil organic matter and biology, including mycorrhizas, which are affected by tillage, herbicides, and crop genotype. Here, we test whether winter wheat yields, mycorrhization, and shoot health can be improved simply by adopting less intensive tillage and adding commercial mycorrhizal inoculum to long-term arable fields, or if 3-year grass-clover leys followed direct drilling is more effective for biological regeneration of soil with reduced N fertiliser. We report a trial of mycorrhization, ear pathology, and yield performance of the parents and four double haploid lines from the Avalon x Cadenza winter wheat population in a long-term arable field that is divided into replicated treatment plots. These plots comprised wheat lines grown using ploughing or disc cultivation for 3 years, half of which received annual additions of commercial arbuscular mycorrhizal (AM) inoculum, compared to 3-year mown grass-clover ley plots treated with glyphosate and direct-drilled. All plots annually received 35 kg of N ha^-1 fertiliser without fungicides. The wheat lines did not differ in mycorrhization, which averaged only 34% and 40% of root length colonised (RLC) in the ploughed and disc-cultivated plots, respectively, and decreased with inoculation. In the ley, RLC increased to 52%. Two wheat lines were very susceptible to a sooty ear mould, which was lowest in the ley, and highest with disc cultivation. AM inoculation reduced ear infections by >50% in the susceptible lines. In the ley, yields ranged from 7.2 to 8.3 t ha^-1, achieving 92 to 106% of UK average wheat yield in 2018 (7.8 t ha^-1) but using only 25% of average N fertiliser. Yields with ploughing and disc cultivation averaged only 3.9 and 3.4 t ha^-1, respectively, with AM inoculum reducing yields from 4.3 to 3.5 t ha^-1 in ploughed plots, with no effect of disc cultivation. The findings reveal multiple benefits of reintegrating legume-rich leys into arable rotations as part of a strategy to regenerate soil quality and wheat crop health, reduce dependence on nitrogen fertilisers, enhance mycorrhization, and achieve good yields.

Ploidy influences wheat mesophyll cell geometry, packing and leaf function

Leaf function is influenced by leaf structure, which is itself related not only to the spatial arrangement of constituent mesophyll cells, but also their size and shape. In this study, we used confocal microscopy to image leaves of Triticum genotypes varying in ploidy level to extract 3D information on individual mesophyll cell size and geometry. Combined with X-ray Computed Tomography and gas exchange analysis, the effect of changes in wheat mesophyll cell geometry upon leaf structure and function were investigated. Mesophyll cell size and shape were found to have changed during the course of wheat evolution. An unexpected linear relationship between mesophyll cell surface area and volume was discovered, suggesting anisotropic scaling of mesophyll cell geometry with increasing ploidy. Altered mesophyll cell size and shape were demonstrated to be associated with changes in mesophyll tissue architecture. Under experimental growth conditions, CO2 assimilation did not vary with ploidy, but stomatal conductance was lower in hexaploid plants, conferring a greater instantaneous water-use efficiency. We propose that as wheat mesophyll cells have become larger with increased ploidy, this has been accompanied by changes in cell geometry and packing which limit water loss while maintaining carbon assimilation.

Frontal Brain Activity and Subjective Arousal During Emotional Picture Viewing in Nightmare Sufferers

Nightmares are intensely negative dreams that awaken the dreamer. Frequent nightmares are thought to reflect an executive deficit in regulating arousal. Within a diathesis-stress framework, this arousal is specific to negative contexts, though a differential susceptibility framework predicts elevated arousal in response to both negative and positive contexts. The current study tested these predictions by assessing subjective arousal and changes in frontal oxyhemoglobin (oxyHB) concentrations during negative and positive picture-viewing in nightmare sufferers (NM) and control subjects (CTL). 27 NM and 27 CTL subjects aged 18–35 rated subjective arousal on a 1–9 scale following sequences of negative, neutral and positive images; changes in oxyHB were measured by Near-Infrared Spectroscopy (NIRS) using a 2 × 4 template on the frontal pole. Participants also completed the Highly Sensitive Person Scale, a trait marker for differential susceptibility; and completed a dream diary reporting negative and positive dream emotionality. The NM group had higher trait sensitivity, yet higher ratings of negative but not positive emotion in diary dreams. NM compared to CTL subjects reported higher subjective arousal in response to picture-viewing regardless of valence. Dysphoric dream distress, measured prospectively, was negatively associated with frontal activation when viewing negative pictures. Results suggest NM sufferers are highly sensitive to images regardless of valence according to subjective measures, and that there is a neural basis to level of trait and prospective nightmare distress. Future longitudinal or intervention studies should further explore positive emotion sensitivity and imagery in NM sufferers.

'PDSAFE' - a multi-dimensional model of falls-rehabilitation for people with Parkinson's. A mixed methods analysis of therapists' delivery and experience

OBJECTIVE

To explore the clinical reasoning of physiotherapists using PDSAFE; according to disease severity and their experiences of treatment delivery in a large fall-prevention trial for people with Parkinson's (PwP).

DESIGN

A descriptive study of delivering PDSAFE. Semi-structured interviews explored therapists' experiences.

SETTING

A two-group, home-based, multi-centred, single-blinded, randomised controlled trial showed no overall effect on fall reduction between groups but demonstrated a significant secondary effect relating to disease severity with benefits to balance, falls efficacy and near-falls for all.

PARTICIPANTS

Physiotherapists with a background in neurology and older-person rehabilitation were trained in the delivery of PDSAFE INTERVENTION: A multi-dimensional, individually tailored and progressive, home-based programme.

RESULTS

Fifteen physiotherapists contributed to the 2587 intervention sessions from the PDSAFE trial and six of those physiotherapists took part in the interviews. The personalised intervention was reflected in the range of strategies and exercises prescribed. Most commonly prescribed fall-avoidance strategies were 'Avoiding tripping', 'Turning' and 'Freezing Cues' and all possible combinations of balance and strength training within the programme were selected. PwP with greater disease severity were more likely to have received less challenging strategies, balance and strengthening exercises than those with lower disease severity. Therapists considered the focus on fall events and fall avoidance strategies an improvement on 'impairment only' treatment. The presence of cognitive deficits, co-morbidities and dyskinesia were the most challenging aspects of delivering the intervention.

CONCLUSION

Falls management for PwP is complex and compounded by the progressive nature of the condition. Physiotherapists both delivered and positively received PDSAFE. (248 words) The trial registration number is ISRCTN 48152791.

Exploring Australian pharmacists' perceptions and attitudes toward codeine up-scheduling from over-the-counter to prescription only

Objective:

Explore the perceptions, attitudes and experiences of pharmacists relating to the up-scheduling of low dose codeine containing analgesics and the impact on pharmacy practice.

Methods:

A mixed design method was used consisting of an anonymous online questionnaire survey to quantitatively capture broad pre-scheduling change perceptions paired with a series of in-depth post-scheduling semi-structured interviews to provide a qualitative picture of the impact of codeine up-scheduling on pharmacy practice in Australia.

Results:

A total of 191 pharmacists completed the quantitative survey and 10 participated in the in-depth interview. The majority of respondents supported the decision to up-schedule over-the-counter combination products containing codeine to some degree. Three main themes emerged from the data: pharmacists’ perceptions of the codeine up-scheduling decision, preparing for the up-schedule and impact of the up-schedule on pharmacy practice. Pharmacists were concerned about the impact of up-scheduling on the pharmacy business, patient access to pain relief and the diminishment of their professional role.

Conclusions:

There were diverse perceptions, preparedness and impact on practice regarding the up-scheduling of low dose codeine products. Further research should be conducted to gauge if and how these perceptions have changed over time and to identify whether pain is being managed more effectively post codeine up-scheduling.

Core competencies for Australian pharmacists when supplying prescribed opioids: a modified Delphi study

Background In the past decade, there has been an increase in prescription opioid related harms. These include dependence, non-fatal and fatal overdose. Pharmacists play a an important role in safe opioid supply. As most opioids are supplied through pharmacies, pharmacists are in a prime position to reduce harms associated with opioid use. Development of specific core competencies for pharmacists may facilitate consistent and safer opioid supply. Objective To reach consensus on which competency items identified by the Association of Faculties of Pharmacy of Canada's Opioid Working Group are considered core competencies for Australian pharmacists in opioid supply and assess expert pharmacists' perceptions of how well these competencies are currently met by practicing pharmacists. Setting Expert pharmacists in the area of opioid supply from across Australia. Method A series of questionnaires were presented to Australian opioid expert pharmacists via a modified Delphi study, with the aim to reach consensus on which items should be considered competencies for opioid supply by Australian pharmacists. Items were rated on a 6-point Likert scale and analysed using Statistical Package for the Social Sciences^® (SPSS). Participants were also asked to rate how well they perceived that currently practicing pharmacists met each of these competency items. Main outcome measure Consensus on competency items for pharmacists when supplying prescribed opioids. Results All competency items presented to participants reached immediate agreement. When rating whether participants perceived currently practicing pharmacists met these competencies, results were variable. The competencies that participants rated practicing pharmacist met to a higher degree reflected knowledge and skills items that can be applied to all medications and were not opioid specific. The lower rated competencies appeared to be related to newer or more complex or specialised areas of opioid supply. Conclusion There was strong agreement by participants on what should be considered core competencies for Australian pharmacists in opioid supply. Given the large number of items identified, further research may help determine priorities for training and education.

Current Treatment Strategies for Intracranial Aneurysms: An Overview

Intracranial aneurysm is a leading cause of stroke. Its treatment has evolved over the past 2 decades. This review summarizes the treatment strategies for intracranial aneurysms from 3 different perspectives: open surgery approach, transluminal treatment approach, and new technologies being used or trialed. We introduce most of the available treatment techniques in detail, including contralateral clipping, wrapping and clipping, double catheters assisting coiling and waffle-cone technique, and so on. Data from major trials such as Analysis of Treatment by Endovascular approach of Non-ruptured Aneurysms (ATENA), Internal Subarachnoid Trial (ISAT), Clinical and Anatomical Results in the Treatment of Ruptured Intracranial Aneurysms (CLARITY), and Barrow Ruptured Aneurysm Trial (BRAT) as well as information from other clinical reports and local experience are reviewed to suggest a clinical pathway for treating different types of intracranial aneurysms. It will be a valuable supplement to the current existing guidelines. We hope it could help assisting real-time decision-making in clinical practices and also encourage advancements in managing the disease.

HumMod: A Modeling Environment for the Simulation of Integrative Human Physiology

Mathematical models and simulations are important tools in discovering key causal relationships governing physiological processes. Simulations guide and improve outcomes of medical interventions involving complex physiology. We developed HumMod, a Windows-based model of integrative human physiology. HumMod consists of 5000 variables describing cardiovascular, respiratory, renal, neural, endocrine, skeletal muscle, and metabolic physiology. The model is constructed from empirical data obtained from peer-reviewed physiological literature. All model details, including variables, parameters, and quantitative relationships, are described in Extensible Markup Language (XML) files. The executable (HumMod.exe) parses the XML and displays the results of the physiological simulations. The XML description of physiology in HumMod's modeling environment allows investigators to add detailed descriptions of human physiology to test new concepts. Additional or revised XML content is parsed and incorporated into the model. The model accurately predicts both qualitative and quantitative changes in clinical and experimental responses. The model is useful in understanding proposed physiological mechanisms and physiological interactions that are not evident, allowing one to observe higher level emergent properties of the complex physiological systems. HumMod has many uses, for instance, analysis of renal control of blood pressure, central role of the liver in creating and maintaining insulin resistance, and mechanisms causing orthostatic hypotension in astronauts. Users simulate different physiological and pathophysiological situations by interactively altering numerical parameters and viewing time-dependent responses. HumMod provides a modeling environment to understand the complex interactions of integrative physiology. HumMod can be downloaded at http://hummod.org

Systems biology and integrative physiological modelling

Over the last 10 years, 'Systems Biology' has focused on the integration of biology and medicine with information technology and computation. The current challenge is to use the discoveries of the last 20 years, such as genomics and proteomics, to develop targeted therapeutical strategies. These strategies are the result of understanding the aetiologies of complex diseases. Scientists predict the data will make personalized medicine rapidly available. However, the data need to be considered as a highly complex system comprising multiple inputs and feedback mechanisms. Translational medicine requires the functional and conceptual linkage of genetics to proteins, proteins to cells, cells to organs, organs to systems and systems to the organism. To help understand the complex integration of these systems, a mathematical model of the entire human body, which accurately links the functioning of all organs and systems together, could provide a framework for the development and testing of new hypotheses that will be important in clinical outcomes. There are several efforts to develop a 'Human Physiome', with the strengths and weaknesses of each being presented here. The development of a 'Human Model', with verification, documentation and validation of the underlying and integrative responses, is essential to provide a usable environment. Future development of a 'Human Model' requires integrative physiologists working in collaboration with other scientists, who have expertise in all areas of human biology, to develop the most accurate and usable human model.

The association between money and opinion in academic emergency medicine

OBJECTIVES

Financial conflicts of interest have come under increasing scrutiny in medicine, but their impact has not been quantified. Our objective was to use the results of a national survey of academic emergency medicine (EM) faculty to determine if an association between money and personal opinion exists.

METHODS

We conducted a web-based survey of EM faculty. Opinion questions were analyzed with regard to whether the respondent had either 1) received research grant money or 2) received money from industry as a speaker, consultant, or advisor. Responses were unweighted, and tests of differences in proportions were made using Chi-squared tests, with p<0.05 set for significance.

RESULTS

We received responses from 430 members; 98 (23%) received research grants from industry, while 145 (34%) reported fee-for-service money. Respondents with research money were more likely to be comfortable accepting gifts (40% vs. 29%) and acting as paid consultants (50% vs. 37%). They had a more favorable attitude with regard to societal interactions with industry and felt that industry-sponsored lectures could be fair and unbiased (52% vs. 29%). Faculty with fee-for-service money mirrored those with research money. They were also more likely to believe that industry-sponsored research produces fair and unbiased results (61% vs. 45%) and less likely to believe that honoraria biased speakers (49% vs. 69%).

CONCLUSION

Accepting money for either service or research identified a distinct population defined by their opinions. Faculty engaged in industry-sponsored research benefitted socially (collaborations), academically (publications), and financially from the relationship.

Cardiovascular adaptations to long-duration head-down bed rest

INTRODUCTION

Orthostatic hypotension is a serious risk for crewmembers returning from spaceflight. Numerous cardiovascular mechanisms have been proposed to account for this problem, including vascular and cardiac dysfunction, which we studied during bed rest.

METHODS

Thirteen subjects were studied before and during bed rest. Statistical analysis was limited to the first 49-60 d of bed rest and compared to pre-bed rest data. Ultrasound data were collected on vascular and cardiac structure and function. Tilt testing was conducted for 30 min or until presyncopal symptoms intervened.

RESULTS

Plasma volume was significantly reduced (15%) by day 7 of bed rest. Flow-mediated dilation in the leg was significantly increased at bed rest day 49 (6% from pre-bed rest). Arterial responses to nitroglycerin differed in the arm and leg, but did not change as a result of bed rest. Anterior tibial artery intimal-medial thickness markedly decreased at bed rest days 21 (21%), 35 (22%), and 49 (19%). Several cardiac functional parameters, including isovolumic relaxation time (73 ms to 85 ms at day 7) and myocardial performance index, were significantly increased (0.41 to 0.49 by day 7 of bed rest; indicating a decrease in cardiac function) during bed rest. There was a trend for decreased orthostatic tolerance following 60 d of bed rest (P = 0.1).

DISCUSSION

Our data suggest that bed rest altered cardiovascular structure and function in a pattern similar to short-duration spaceflight. Additionally, the vascular alterations were primarily seen in the lower body, while vessels of the upper body were unaffected.

Early treatment for non-ST-segment elevation acute coronary syndrome is associated with appropriate discharge care

BACKGROUND

Acute treatment is associated with improved in-hospital outcomes for patients with non-ST-segment elevation acute coronary syndrome (NSTE ACS).

HYPOTHESIS

Patients who receive appropriate acute treatment are more likely to receive guideline-recommended therapy at hospital discharge.

METHODS

Use of aspirin (ASA), beta-blockers, and clopidogrel was evaluated in the first 24 hours and upon hospital discharge according to the 2002 American College of Cardiology/American Heart Association (ACC AHA) guidelines for NSTE ACS. We compared the relationship between 3 groups: (1) ASA therapy given in the emergency department (ED); (2) ASA therapy not given in the ED, but within the first 24 hours; and (3) no acute ASA treatment. The ASA data set includes 10,468 high risk patients with positive cardiac biomarkers or ischemic ST-segment changes on ECG from the Can Rapid Risk Stratification of Unstable Angina Patients Suppress Adverse Outcomes with Early Implementation of the ACC/AHA Guidelines (CRUSADE) Quality Improvement Initiative. Beta-blocker therapy was evaluated in 11,838 and clopidogrel treatment in 17,513 patients presenting to over 345 US hospitals.

RESULTS

Patients who received acute ASA in the ED, ASA in the first 24 hours but not in the ED, and patients who did not receive ASA therapy within 24 hours had discharge ASA treatment rates of 91.8%, 91.4%, and 55.6%, respectively (P < 0.0001). Patients eligible for beta-blocker and clopidogrel therapy had discharge beta-blocker treatment rates of 91.1%, 92.4%, and 46.6% (P < 0.0001), and discharge clopidogrel treatment rates of 86.6%, 92.4%, and 38.5% (P < 0.0001), respectively.

CONCLUSIONS

Acute treatment for NSTE ACS in-hospital is associated with appropriate treatment on hospital discharge. This link between early treatment and discharge therapy may lead to new approaches ensuring the delivery of high-quality, guideline-based care for patients with NSTE ACS.

Guiding BMP adoption to improve water quality in various estuarine ecosystems in Western Australia

The Australian Government's Coastal Catchment Initiative (CCI) seeks to achieve targeted reductions in nutrient pollution to key coastal water quality hotspots, reducing algal blooms and fish kills. Under the CCI a Water Quality Improvement Plan (WQIP) is being prepared for targeted estuaries (Swan-Canning, near Perth, and the Vasse-Geographe, 140 km south of Perth) to address nutrient pollution issues. A range of projects are developing, testing and implementing agricultural Best Management Practices (BMPs) to reduce excessive loads of nutrients reaching the receiving waters. This work builds on progress-to-date achieved in a similar project in the Peel-Harvey Catchment (70 km south of Perth). It deals with the necessary steps of identifying the applicability of BMPs for nutrient attenuation, developing and promoting BMPs in the context of nutrient use and attenuation on farm and through catchments and estimating the degree to which BMP implementation can protect receiving waters. With a range of BMPs available with varying costs and effectiveness, a Decision Support System (DSS) to guide development of the WQIP and implementation of BMPs to protect receiving waters, is under development. As new information becomes available the DSS will be updated to ensure relevance and accuracy for decision-making and planning purposes. The DSS, calibrated for application in the catchments, will play a critical role in adaptive implementation of the WQIP by assessing the effect of land use change and management interventions on pollutant load generation and by providing a tool to guide priority setting and investment planning to achieve agreed WQIP load targets.

Medical device databases: a scoping study

Databases of medical devices were identified via complex search strategies to discover breadth and depth of coverage. The databases could be categorised into three types: Product, Business and Regulation. Evaluation of the databases uncovered several issues including: lack of continuity relating to the level of information provided; and little or no evidence that evaluation criteria has been applied to the databases. Other results of the scoping study suggest that a comprehensive medical device database must address the information requirements of a diverse group of stakeholders including multiple professional disciplines as well as patients and their carers. In order to support the needs of this disparate group of users, it is essential to develop a policy to support clear pathways to validate information gathering, representation, and retrieval activities.

A technology roadmap for rehabilitation engineering

During September 2003, interviews took place to collect data to develop a technology roadmap for rehabilitation engineering. The emerging themes were used to create the roadmap. Criteria were developed to endorse the data prior to the representation process. Added value was by the collection and representation of supporting evidence. Roadmapping 'best practice will facilitate the capture of essential data, represented in a format that is accessible, delivered in an appropriate format, to the right person at the right time.

Management of Acute Decompensated Heart Failure in the Emergency Department

Heart failure, a disease of epidemic proportions, has a tremendous clinical and financial impact on the US health care system. With more than 5 million Americans diagnosed with heart failure and 5-year mortality approaching 50%, it is the most common cause of hospitalization in patients older than 65 years and is the single most expensive diagnosis in the US health care system. Because the average US hospital loses more than 1000 dollars per heart failure admission, effective therapies that decrease length of stay, reduce hospital costs, and prevent 30-day readmissions are needed. This article reviews the relevant pathophysiology of heart failure, discusses the newest diagnostic strategies for emergency department diagnoses, evaluates recent advances and effects of early aggressive therapies, and presents a suggested algorithm for the treatment of acutely decompensated heart failure in emergency departments.

Status report: Development of emergency medicine research since the Macy Report

In Williamsburg, VA, April 17 to 20, 1994, the Josiah Macy, Jr. Foundation sponsored a conference entitled "The Role of Emergency Medicine in the Future of American Medical Care," a report on which was published in Annals in 1995. This report promulgated recommendations for the development and enhancement of academic departments of emergency medicine and a conference to develop an agenda for research in emergency medicine. The American College of Emergency Physicians' Research Committee, along with several ad hoc members, presents updates in several of the areas addressed by the Macy Report and subsequent conferences, as a status report for the development of emergency medicine research as a whole, as of late 2002.

The impact of molecular markers on the wheat breeding paradigm

We briefly review the limited application of marker assisted selection in past wheat breeding programmes, and contrast the current situation, where increasingly it has become feasible to tag almost any gene with a microsatellite assay. Although this capability is having an impact on the conduct of large breeding programmes, a much more profound change in breeding strategy will become possible when SNP technology has matured sufficiently so that the throughput of molecular marker-based genotyping will be able to keep pace with the numbers of plants that breeders can handle in the field. We discuss the considerations that will need to be addressed in the generation of a new breeding paradigm to take advantage of the genomics revolution.

Is deep hypothermia necessary for unilateral antegrade cerebral perfusion during circulatory arrest? A magnetic resonance study in a pig model

OBJECTIVE

Localized (31)P magnetic resonance spectroscopy (MRS) was used to investigate whether unilateral antegrade cerebral perfusion (U-ACP) could maintain normal energy metabolism and intracellular pH (pHi) in both hemispheres of the brain during deep (15 degrees C) and moderate (28 degrees C) hypothermic circulatory arrest (HCA).

METHODS

Eleven pigs were exposed to 120 min of U-ACP during HCA at 15 degrees C (group I, n=6) or 28 degrees C (group II, n=5), followed by 60 min of cardiopulmonary bypass (CPB) at 37 degrees C. Localized (31)P MR spectra were acquired every 30 min. Histopathology was performed at the completion of each experiment.

RESULTS

MR recorded no changes in energy metabolites (phosphocreatine and ATP), or pHi during U-ACP in either group, and no significant differences were found in any of the energy metabolites or pHi between the left and right hemispheres. Histopathology showed no significant morphological changes in the neurons.

CONCLUSIONS

During either deep or moderate HCA, unilateral ACP through the right axillary artery prevents ischemic events in both hemispheres of normal pig brains. Deep hypothermia may not be necessary when using U-ACP.

Increase of fat oxidation and weight loss in obese mice caused by chronic treatment with human growth hormone or a modified C-terminal fragment

OBJECTIVE

To observe the chronic effects of human growth hormone (hGH) and AOD9604 (a C-terminal fragment of hGH) on body weight, energy balance, and substrate oxidation rates in obese (ob/ob) and lean C57BL/6Jmice. In vitro assays were used to confirm whether the effects of AOD9604 are mediated through the hGH receptor, and if this peptide is capable of cell proliferation via the hGH receptor.

METHOD

Obese and lean mice were treated with hGH, AOD or saline for 14 days using mini-osmotic pumps. Body weight, caloric intake, resting energy expenditure, fat oxidation, glucose oxidation, and plasma glucose, insulin and glycerol were measured before and after treatment. BaF-BO3 cells transfected with the hGH receptor were used to measure in vitro 125I-hGH receptor binding and cell proliferation.

RESULTS

Both hGH and AOD significantly reduced body weight gain in obese mice. This was associated with increased in vivo fat oxidation and increased plasma glycerol levels (an index of lipolysis). Unlike hGH, however, AOD9604 did not induce hyperglycaemia or reduce insulin secretion. AOD9604 does not compete for the hGH receptor and nor does it induce cell proliferation, unlike hGH.

CONCLUSIONS

Both hGH and its C-terminal fragment reduce body weight gain, increase fat oxidation, and stimulate lipolysis in obese mice, yet AOD9604 does not interact with the hGH receptor. Thus, the concept of hGH behaving as a pro-hormone is further confirmed. This data shows that fragments of hGH can act in a manner novel to traditional hGH-stimulated pathways.

Microsatellite and mitochondrial DNA homogeneity among phenotypically diverse crossbill taxa in the UK

Genetic differentiation within and between the three morphologically divergent crossbill species extant in the UK was assessed by comparison of allele frequencies at five unlinked microsatellite loci and DNA sequence variation across the mitochondrial control region. No significant differences in microsatellite allele frequency were found either between different populations of the same species or between the crossbill species themselves. A similar lack of genetic divergence was apparent from the mitochondrial sequence data. We resolved 33 different haplotypes, separated by low levels of sequence divergence (0-0.15%). Levels of divergence within and between species were not significantly different. Haplotypes formed a polyphyletic phylogeny, indicating that the crossbill species do not form genetically separate clades. Discordance between neutral DNA polymorphisms and adaptive morphological variation is discussed in relation to defining the systematic relationship between crossbill forms. If adaptive differences have arisen without a concomitant divergence in neutral DNA then attempting to define crossbill types from microsatellite and mitochondrial DNA without recourse to ecology and behaviour may be misleading.

Ranking fMRI time courses by minimum spanning trees: assessing coactivation in fMRI

In fMRI, time courses with similar temporal "activation" patterns may belong to different brain regions (i.e., these regions are functionally connected, coactivated). A group of time courses (TCs) corresponding to a particular type of temporal activation pattern should be maximally self-consistent (homogeneous). We demonstrate that ordering a group of multidimensional fMRI time courses by a minimum spanning tree (MST) may be used to investigate the temporal homogeneity of a group of TCs. We show the utility of MST ranking for data-driven analysis methods in investigating coactivation in fMRI. MST ranking is equally useful for hypothesis-led methods. Furthermore, MST ranking enables pairwise comparisons of groups/clusters (i.e., any collection of TCs, no matter how derived) of fMRI time courses.

Towards non-invasive screening of skin lesions by near-infrared spectroscopy

A noninvasive tool for skin tumor diagnosis would be a useful clinical adjunct. The purpose of this study was to determine whether near-infrared spectroscopy can be used to noninvasively characterize skin lesions. In vivo visible- and near-infrared spectra (400--2500 nm) of skin neoplasms (actinic keratoses, basal cell carcinomas, banal common acquired melanocytic nevi, dysplastic melanocytic nevi, actinic lentigines, and seborrheic keratoses) were collected by placing a fiberoptic probe on the skin. Paired t tests, repeated measures analysis of variance and linear discriminant analysis were used to determine whether significant spectral differences existed and whether spectra could be classified according to lesion type. Paired t tests showed significant differences (p < 0.05) between normal skin and skin lesions in several areas of the near-infrared spectrum. In addition, significant differences were found between the lesion groups by analysis of variance. Linear discriminant analysis classified spectra from benign lesions compared with premalignant or malignant lesions with high accuracy. Near-infrared spectroscopy is a promising noninvasive technique for the screening of skin lesions.

The effects of retrograde cardioplegia technique on myocardial perfusion and energy metabolism: a magnetic resonance imaging and localized phosphorus 31 spectroscopy study in isolated pig hearts

OBJECTIVE

The present work was designed to study the myocardial perfusion and energy metabolism during retrograde cardioplegia performed with different methods, including deep coronary sinus cardioplegia, coronary sinus orifice cardioplegia, and right atrial cardioplegia.

METHODS

Isolated pig hearts were subjected to antegrade cardioplegia, right atrial cardioplegia, deep coronary sinus cardioplegia, and coronary sinus orifice cardioplegia in a random order. Cardioplegic distribution was assessed by T1-weighted magnetic resonance imaging in 1 group of hearts (n = 8). The flow dynamics of cardioplegia were assessed by T2*-weighted imaging in a second group of hearts (n = 8).

RESULTS

T1-weighted images revealed an apparent perfusion defect in the posterior wall of the left ventricle, the posterior portion of the interventricular septum, and the right ventricular free wall during deep coronary sinus cardioplegia. The perfusion defect observed in the first 2 regions with deep coronary sinus cardioplegia resolved with coronary sinus orifice cardioplegia. Right atrial cardioplegia provided the most homogeneous perfusion to all regions of the myocardium relative to the other 2 retrograde cardioplegia modalities. T2*-weighted images showed that the 3 retrograde cardioplegia modalities provided similar cardioplegic flow velocities. Localized phosphorus 31 spectroscopy showed that the levels of adenosine triphosphate and phosphocreatine were significantly lower in the posterior wall (adenosine triphosphate, 42.86% +/- 5.91% of its initial value; phosphocreatine, 11.43% +/- 11.3%) than the anterior wall (adenosine triphosphate, 89.19% +/- 8.83%; phosphocreatine, 59.54% +/- 12.58%) of the left ventricle during 70 minutes of normothermic deep coronary sinus cardioplegia.

CONCLUSIONS

Deep coronary sinus cardioplegia results in myocardial ischemia in the posterior wall of the left ventricle and the posterior portion of the interventricular septum, as well as in the right ventricular free wall. Coronary sinus orifice cardioplegia improves cardioplegic distribution in these regions. Relative to deep coronary sinus cardioplegia and coronary sinus orifice cardioplegia, right atrial cardioplegia provides the most homogeneous perfusion.

Novelty indices: identifiers of potentially interesting time-courses in functional MRI data

In a systematic study of hybrid MR time-series with simulated "activation" (contrast-to-noise range 1-10) we investigated the power and compared the ability of the "novelty indices" (NI) kurtosis, negentropy, and 1-lag autocorrelation, to discriminate between potentially interesting ("structured") and uninteresting ("noisy") time-courses (TCs). NIs may be employed as preprocessing tools to focus only on the interesting TCs prior to any further exploratory or confirmatory approach.

Correlator beware: correlation has limited selectivity for fMRI data analysis

Groups of time-courses created from fMRI data by the frequently used correlation analysis are often highly heterogeneous. This heterogeneity is due to the limited selectivity of correlation when trying to match brain time-courses to an externally imposed activation paradigm. Thus, this process unnecessarily generates many type I errors (false positives). Furthermore, as a consequence of the heterogeneity, time-courses identified and grouped by correlation may in fact describe different activations. After demonstrating this inadequacy, we give one particular approach to partition such a heterogeneous group into internally more homogeneous subgroups, using Kendall's coefficient of concordance W, and show its applicability and application to both simulated and in vivo data. Such group partition and "purification" will help subsequent inferential methods to deal more efficiently with false positives.

Motor area activity during mental rotation studied by time-resolved single-trial fMRI

The functional equivalence of overt movements and dynamic imagery is of fundamental importance in neuroscience. Here, we investigated the participation of the neocortical motor areas in a classic task of dynamic imagery, Shepard and Metzler's mental rotation task, by time-resolved single-trial functional Magnetic Resonance Imaging (fMRI). The subjects performed the mental-rotation task 16 times, each time with different object pairs. Functional images were acquired for each pair separately, and the onset times and widths of the activation peaks in each area of interest were compared to the response times. We found a bilateral involvement of the superior parietal lobule, lateral premotor area, and supplementary motor area in all subjects; we found, furthermore, that those areas likely participate in the very act of mental rotation. We also found an activation in the left primary motor cortex, which seemed to be associated with the right-hand button press at the end of the task period.

Resampling as a cluster validation technique in fMRI

Exploratory, data-driven analysis approaches such as cluster analysis, principal component analysis, independent component analysis, or neural network-based techniques are complementary to hypothesis-led methods. They may be considered as hypothesis generating methods. The representative time courses they produce may be viewed as alternative hypotheses to the null hypothesis, i.e., "no activation." We present here a resampling technique to validate the results of exploratory fuzzy clustering analysis. In this case an alternative hypothesis is represented by a cluster centroid. For both simulated and in vivo functional magnetic resonance imaging data, we show that by permutation-based resampling, statistical significance may be computed for each voxel belonging to a cluster of interest without parametric distributional assumptions.

Comparison of two exploratory data analysis methods for fMRI: fuzzy clustering vs. principal component analysis

Exploratory data-driven methods such as Fuzzy clustering analysis (FCA) and Principal component analysis (PCA) may be considered as hypothesis-generating procedures that are complementary to the hypothesis-led statistical inferential methods in functional magnetic resonance imaging (fMRI). Here, a comparison between FCA and PCA is presented in a systematic fMRI study, with MR data acquired under the null condition, i.e., no activation, with different noise contributions and simulated, varying "activation." The contrast-to-noise (CNR) ratio ranged between 1-10. We found that if fMRI data are corrupted by scanner noise only, FCA and PCA show comparable performance. In the presence of other sources of signal variation (e.g., physiological noise), FCA outperforms PCA in the entire CNR range of interest in fMRI, particularly for low CNR values. The comparison method that we introduced may be used to assess other exploratory approaches such as independent component analysis or neural network-based techniques.

Assessment of cluster homogeneity in fMRI data using Kendall's coefficient of concordance

In fMRI both model-led and exploratory data-driven methods are used to identify groups of voxels according to their correlation either with an external reference or with some similarity measure. Here we present a technique to assess intragroup homogeneity using Kendall's coefficient of concordance W once groups have been identified. We show that the time-courses belonging to the group may be ranked according to their contribution to the overall concordance and describe an algorithm for group purification. We suggest the use of W as a cluster validation index in exploratory data analysis approaches, such as fuzzy or hard clustering, principal component analysis, independent component analysis and Kohonen maps.