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This paper reports the molecular organization and mechanical properties of electrospun, post-drawn polyacrylonitrile (PAN) nanofibers. Without post-drawing, the polymer chain was kinked and oriented in hexagonal crystalline structures. Immediate post-drawing in the semi-solid state disrupted the crystal structures and chain kink at maximum draw ratio. Structural re-orientation at maximum draw resulted in a 500% increase in Young's modulus and a 100% increase in ultimate tensile strength. By applying post-drawing to electrospinning it may be possible to obtain PAN fibers and PAN-derived carbon fibers with enhanced mechanical properties compared to available fabrication technologies.
FFQ, food diaries and 24 h recall methods represent the most commonly used dietary assessment tools in human studies on nutrition and health, but food intake biomarkers are assumed to provide a more objective reflection of intake. Unfortunately, very few of these biomarkers are sufficiently validated. This review provides an overview of food intake biomarker research and highlights present research efforts of the Joint Programming Initiative ‘A Healthy Diet for a Healthy Life’ (JPI-HDHL) Food Biomarkers Alliance (FoodBAll). In order to identify novel food intake biomarkers, the focus is on new food metabolomics techniques that allow the quantification of up to thousands of metabolites simultaneously, which may be applied in intervention and observational studies. As biomarkers are often influenced by various other factors than the food under investigation, FoodBAll developed a food intake biomarker quality and validity score aiming to assist the systematic evaluation of novel biomarkers. Moreover, to evaluate the applicability of nutritional biomarkers, studies are presently also focusing on associations between food intake biomarkers and diet-related disease risk. In order to be successful in these metabolomics studies, knowledge about available electronic metabolomics resources is necessary and further developments of these resources are essential. Ultimately, present efforts in this research area aim to advance quality control of traditional dietary assessment methods, advance compliance evaluation in nutritional intervention studies, and increase the significance of observational studies by investigating associations between nutrition and health.
Worldwide approximately 3.6 million people aged 50 and older are living and ageing with the human immunodeficiency virus (HIV). Few studies have explored successful ageing from the insider perspective of those living well and ageing with HIV. This study draws upon the lived experience and wisdom of older, HIV-positive adults living in Ontario, Canada in order to understand their views and strategies for successful ageing. This qualitative study involved semi-structured interviews with 30 individuals age 50 years and older who are HIV-positive. Purposive sampling techniques were used to recruit individuals who shared their experiences of successful ageing. Constructivist grounded theory coding techniques were used for analysis. Themes related to successful ageing included resilience strategies and challenges, social support and environmental context. Stigma and struggles to maintain health were identified as impediments to successful ageing. Models of successful ageing must take into account the potential for a subjective appraisal of success in populations suffering from chronic and life-threatening illnesses including HIV. Practitioners can draw upon organically existent strengths in this population in order to provide intervention development for older adults around the world who are struggling to manage their HIV.
The ApRES (autonomous phase-sensitive radio-echo sounder) instrument is a robust, lightweight and relatively inexpensive radar that has been designed to allow long-term, unattended monitoring of ice-shelf and ice-sheet thinning. We describe the instrument and demonstrate its capabilities and limitations by presenting results from three trial campaigns conducted in different Antarctic settings. Two campaigns were ice sheet-based – Pine Island Glacier and Dome C – and one was conducted on the Ross Ice Shelf. The ice-shelf site demonstrates the ability of the instrument to collect a time series of basal melt rates; the two grounded ice applications show the potential to recover profiles of vertical strain rate and also demonstrate some of the limitations of the present system.
The co-occurrence of child conduct problems (CPs) and callous–unemotional (CU) traits confers risk for psychopathy. The oxytocin (OXT) system is a likely candidate for involvement in the development of psychopathy. We tested variations in the OXT receptor gene (OXTR) in CP children and adolescents with varying levels of CU traits. Two samples of Caucasian children, aged 4–16 years, who met DSM criteria for disruptive behavior problems and had no features of autism spectrum disorder, were stratified into low versus high CU traits. Measures were the frequencies of nine candidate OXTR polymorphisms (single nucleotide polymorphisms). In Sample 1, high CU traits were associated with single nucleotide polymorphism rs1042778 in the 3′ untranslated region of OXTR and the CGCT haplotype of rs2268490, rs2254298, rs237889, and rs13316193. The association of rs1042778 was replicated in the second rural sample and held across gender and child versus adolescent age groups. We conclude that polymorphic variation of the OXTR characterizes children with high levels of CU traits and CPs. The results are consistent with a hypothesized role of OXT in the developmental antecedents of psychopathy, particularly the differential amygdala activation model of psychopathic traits, and add genetic evidence that high CU traits specify a distinct subgroup within CP children.
Child conduct problems (CPs) are a robust predictor of adult mental health; the concurrence of callous–unemotional (CU) traits confers specific risk for psychopathy. Psychopathy may be related to disturbances in the oxytocin (OXT) system. Evidence suggests that epigenetic changes in the OXT receptor gene (OXTR) are associated with lower circulating OXT and social–cognitive difficulties. We tested methylation levels of OXTR in 4- to 16-year-old males who met DSM criteria for a diagnosis of oppositional–defiant or conduct disorder and were stratified by CU traits and age. Measures were DNA methylation levels of six CpG sites in the promoter region of the OXTR gene (where a CpG site is a cytosine nucleotide occurs next to a guanine nucleotide in the linear sequence of bases along its lenth, linked together by phosphate binding), and OXT blood levels. High CU traits were associated with greater methylation of the OXTR gene for two cytosine nucleotide and guanine nucleotide phosphate linked sites and lower circulating OXT in older males. Higher methylation correlated with lower OXT levels. We conclude that greater methylation of OXTR characterizes adolescent males with high levels of CU and CPs, and this methylation is associated with lower circulating OXT and functional impairment in interpersonal empathy. The results add genetic evidence that high CU traits specify a distinct subgroup within CP children, and they suggest models of psychopathy may be informed by further identification of these epigenetic processes and their functional significance.
Using data collected by the Ontario HIV Treatment Network Cohort Study, the primary goal of this study was to describe the socio-demographic characteristics of a sample of older people (age 50 and over) from Ontario (n = 1,129) living with HIV/AIDS (PHAs). The secondary goal was to compare four sub-samples of older PHAs: women (10.6%), heterosexual men (16.7%), gay men (65.8%), and bisexual men (6.9%). These groups differed significantly by age, education, income, nationality, race, and time spent living with HIV. Compared to other groups, gay and bisexual men (GBM) reported lower HIV stigma, disclosure stigma, negative self-image stigma, and concern with public attitude stigma. GBM also reported higher mental health quality of life, lower depression scores, and lower maladaptive coping scores. These findings suggest that services for older PHAs, including training for HIV and gerontological providers, may need to cater to the specific needs of these sub-populations.
This study examined everyday action impairment in participants with Parkinson's disease dementia (PDD) by comparison with participants with Parkinson's disease-no dementia (PD) or Alzheimer's disease (AD) and in reference to a neuropsychological model. Participants with PDD (n = 20), PD (n = 20), or AD (n = 20) were administered performance-based measures of everyday functioning that allowed for the quantification of overall performance and error types. Also, caregiver ratings of functional independence were obtained. On performance-based tests, the PDD group exhibited greater functional impairment than the PD group but comparable overall impairment relative to the AD group. Error patterns did not differ between PDD and PD participants but the PDD group demonstrated a higher proportion of commission errors and lower proportion of omission errors relative to the AD group. Hierarchical regression analyses showed omission errors were significantly predicted by neuropsychological measures of episodic memory, whereas commission errors were predicted by both measures of general dementia severity (MMSE) and executive control. Everyday action impairment in PDD differs quantitatively from PD but qualitatively from AD and may be characterized by a relatively high proportion of commission errors—an error type associated with executive control deficits. (JINS, 2012, 18, 1–12)
Nutrition plays a central role in health, with poor dietary habits and nutritional intake being associated with a range of chronic diseases. The aim was to examine grocery purchasing behaviour in relation to chewing ability, dietary knowledge and socio-economic status (SES) among older adults.
Data were collected by mailed survey in 2008. Grocery purchasing was measured using a sixteen-item index of compliance of food purchasing with dietary guidelines. Self-reported number of teeth was classified as an inadequate dentition if less than twenty-one teeth were present. Chewing ability was based on a five-item chewing index. Dietary knowledge was collected using twenty true/false items. SES was assessed using a subjective social status rating representing where people stand in society.
Population survey in Adelaide, South Australia.
Adults aged 60–71 years.
Responses were collected from 444 persons (response rate = 68·8 %). Among dentate persons, 24·4 % had an inadequate dentition with 10·3 % defined as ‘chewing deficient’. Multivariate regression coefficients adjusted for age, sex and income showed chewing deficiency (−5·8) and low SES (−3·6) was associated (P < 0·05) with lower grocery purchasing scores, but dietary knowledge was not statistically significant.
For older adults, chewing deficiency and lower social status were associated with lower compliance with dietary guidelines, independent of dietary knowledge.
This study evaluated the impact of distractor objects and their similarity to target objects on everyday task performance in dementia. Twenty participants with dementia due to Alzheimer’s disease (n = 12) or subcortical vascular disease (n = 8) were videotaped while they performed 3 discrete tasks: (1) make a cup of coffee, (2) wrap a gift, and (3) pack a lunch under two conditions that were counterbalanced across participants. The conditions differed in terms of the type of distractor objects included in the workspace: (1) Target-Related Distractor Condition - distractor objects were functionally and visually similar to target objects (e.g., salt for sugar) (2) Unrelated Distractor Condition - distractors were neither visually nor functionally similar to targets (e.g., glue for sugar). Participants touched (t = 4.19; p < .01) and used (z = 3.00; p < .01) significantly more distractors, made more distractor errors (i.e., substitutions; t = 2.93; p < .01), and took longer to complete tasks (t = 2.27; p < .05) in the Target-Related Distractor condition. The percent of steps accomplished and non-distractor errors did not differ across conditions (t < 1.26; p > .05 for both). In summary, distractors that were similar to targets elicited significant interference effects circumscribed to object selection. (JINS, 2010, 16, 484–494.)
The association between trans-fatty acids (TFA) and cancer risk is poorly understood and remains controversial. It is recognised that unique biological effects are associated with specific isoforms within families of fatty acids such as those belonging to the n-3 fatty acids. Furthermore, the interactions between diet and genetic polymorphisms are increasingly recognised for their potential risk-modifying effects on human health and disease. Therefore, the aim of the present review is to evaluate whether specific TFA isomers and genetic polymorphisms differentially modify cancer risk in prostate, colon and breast cancers in animal and human models. Potential mechanisms of action by which TFA may affect cancer development are also reviewed. Overall, across a number of experimental models and human studies, there is insufficient and inconsistent evidence linking specific TFA isomers to cancers of the prostate, colon and breast. A number of methodological limitations and experimental considerations were identified which may explain the inconsistencies observed across these studies. Therefore, further research is warranted to accurately assess the relationship between TFA and cancer risk.
Pathophysiological stress from acute illness causes metabolic disturbance, including altered hepatic glucose metabolism, increased peripheral insulin resistance and hyperglycaemia. Acute hyperglycaemia is associated with increased morbidity and mortality in patients in intensive care units and patients with acute respiratory disease. The present review will consider mechanisms underlying this association. In normal lungs the glucose concentration of airway secretions is approximately 10-fold lower than that of plasma. Low airway glucose concentrations are maintained against a concentration gradient by active glucose transport. Airway glucose concentrations become elevated if normal homeostasis is disrupted by a rise in blood glucose concentrations or inflammation of the airway epithelium. Elevated airway glucose concentrations are associated with and precede increased isolation of respiratory pathogens, particularly methicillin-resistant Staphylococcus aureus, from bronchial aspirates of patients intubated on intensive care. Markers of elevated airway glucose are associated with similar patterns of respiratory infection in patients admitted with acute exacerbations of chronic obstructive pulmonary disease. Glucose at airway concentrations stimulates the growth of respiratory pathogens, over and above the effect of other nutrients. Elevated airway glucose concentrations may also worsen respiratory disease by promoting local inflammation. Hyperglycaemia may thus promote pulmonary infection, at least in part, by an effect on airway glucose concentrations. Therapeutic options, including systemic control of blood glucose and local manipulation of airway glucose homeostasis, will be considered.
Troyen A. Brennan, chief medical officer of Aetna., Harvard Medical School,
Michelle M. Mello, Ethical Basis of the Practice of Public Health, Harvard School of Public Health,
David M. Studdert, associate professor of law and public health, Harvard School of Public Health,
Approaches for dealing with medical injuries are developing quickly today. Publication of the Institute of Medicine's (IOM's) report, To Err Is Human, in 2000 unleashed a variety of innovative ideas, some of which have already prompted policy changes. But the field of patient safety is in its infancy and policy responses to the problem of medical errors remain in flux, suggesting that significant changes lie ahead in the way we address the challenge of reducing the number of patients injured by medical care.
To help anticipate how these new policies may affect the medical profession and health care industry, it is critical to examine the recent medical malpractice “crisis.” The connections between strategies to reduce medical injury and the medical malpractice system are vital and often overlooked. Developments in the medical liability arena will affect the evolution and eventual shape of methods used to combat error in medicine. Moreover, we believe that medical injury policy can and will significantly affect medical liability policy.
This chapter focuses on the implications of the medical injury/medical malpractice dynamic for physician behavior. It is informed by research on defensive medicine we undertook with support from The Pew Charitable Trusts in 2003 and 2004. This research was motivated in part by the ongoing national crisis in medical liability, which hit Pennsylvania particularly hard from 2001 onward.
Studies have shown that the risk of hypertension in adulthood can be affected by the in utero environment. It is established that hypertension is linked to compromised kidney function and that factors affecting organogenesis can increase the risk of later disease. Prostaglandins (PG) and growth factors are known to play an important role in regulating kidney function and renal organogenesis. The extent, however, to which global energy restriction (where all nutrients are reduced) of the mother can programme later blood pressure control or renal PG and growth factor status is unknown. A study is described that aimed to examine the long-term effects of maternal nutrient restriction (NR) and elucidate their relationship with compromised kidney development. First, it was necessary to establish animal models. A sheep model of 50% NR during specific stages of gestation was used to investigate fetal renal development, whilst a rat model of 50% NR throughout pregnancy was used to investigate postnatal kidney development and adult functioning. Molecular analysis has shown that expression of the growth hormone–insulin-like growth factor (GH–IGF) axis is affected by NR in the fetal sheep kidneys, and that changes are dependent on the timing of NR and whether the fetus is a singleton or a twin. Analysis of the kidneys from the rat model has shown nutritional differences in the expression of PG receptors and the enzymes responsible for PG synthesis and degradation that persist into adulthood. In conclusion, NR does affect the GH–IGF and PG axes, and these changes may be important in the nutritional programming of renal functioning and adult blood pressure control.
New poly(fluorene-thiophene) alternating copolymers are described in which either the dioctylfluorene or bithiophene units in poly(9,9-dioctylfluorene-alt-bithiophene) (F8T2) are replaced by other fluorene or thiophene-based groups, respectively. Improvements in solubility are realized when the bithiophene unit of F8T2 is replaced by dihexylterthiophene or dihexylpentathiophene units. Melting temperatures are also lowered by 50 – 100°C in these polymers when compared to F8T2. Replacement of the bithiophene unit of F8T2 with a dihexylpentathiophene unit also results in a significant improvement in hysteresis (< 2 V vs. 3.5 – 5 V for F8T2). Initial results are also reported on the thermal cleavage of the C8 side groups of F8T2, which yields an insoluble polymeric semiconductor film that continues to exhibit transistor switching characteristics as part of a bottom gate device.
Polyfluorenes are a class of polyaromatic macromolecules that are characterized by an alternating backbone structure that consists of a 9,9-dialkylfluorene unit in combination with another aromatic group. The nature of this aromatic unit plays a key role in the electronic properties of the polymers. For example, polyfluorenes which combine chromophoric and charge transporting aromatic units have received a great deal of attention over the last several years as the emissive layer in polymeric light emitting diodes [LUMATION* Light-Emitting Polymers (LEPs)]. More recently, polyfluorenes have also been designed to perform as the organic semiconducting layer in polymeric field effect transistors (PFETs). This effort has led to a class of polymeric semiconductors with an excellent combination of charge mobility, environmental stability, and processability. One such polymer is the polyfluorene based on an alternating backbone of 9,9-dioctylfluorene and 2,2'-bithiophene units. This material has been shown to have charge mobilities as high as 0.02 cm2/V-s with current on/off ratios of up to 106. The poly(fluorene-bithiophene) is more resistant to doping by atmospheric oxygen than other polymeric semiconductors such as poly(3-hexylthiophene). Inks based on solutions of poly(fluorene-bithiophene) in xylene, mesitylene, and other solvents have also been prepared. The paper will focus on the recent advances in the synthesis, fabrication, and electrical characterization of poly(fluorene-bithiophene). *Trademark of The Dow Chemical Company