Drugs for cardiac arrhythmmias, antithrombotic drugs and lipid modulating drugs

13.1 Drugs for cardiac arrhythmias 13.1.1 Introduction to cardiac arrhythmias 13.1.2 Cardiac action potentials 13.1.3 Mechanisms of cardiac arrhythmias 13.1.3 Class I 13.1.4 Class II 13.1.5 Class III 12.1.6 Class IV 13.1.7 Amiodarone 13.1.8 Adenosine 13.2 Antithrombotic drugs 13.2.1 Thrombus formation 13.2.2 Platelet aggregation and anti-platelet drugs 13.2.3 Coagulation 13.2.4 Anticoagulants 13.2.5 Fibrinolysis and fibrinolytics 13.3. Lipid modulating drugs 13.3.1 Cholesterol 13.3.2 Statins 13.3.3 Fibric acid derivatives 13.3.4 Ezetimibe

Drugs for diabetes and obesity

14.1 Drugs for diabetes 14.1.1 Diabetes mellitus 14.1.2 Physiology of the pancreas 14.1.3 Insulin replacement therapy 14.1.4 Metformin 14.1.5 Acarbose 14.1.6 Sulfonylureas 14.1.7 Glitazones 14.1.8 Glucagon-like peptide-1, exenatide and sitagliptin 14.2 Drugs for obesity 14.2.1 Introduction 14.2.2 Amphetamine 14.2.3 Phentermine 14.2.5 Orlistat

Constructions of children's needs in informal kinship care in rural China

Kinship care is the oldest form of alternative child care in the world. Recent years have witnessed a significant increase in the number of children being placed in kinship care across Western countries. However, in contrast to rapid knowledge advances about formal kinship care, far less is known about the needs of children in informal kinship care, especially in Asian contexts. This thesis and the study upon which it is formed sought to redress this knowledge gap. Qualitative approach was adopted to explore social constructions of children in informal kinship care in rural China. Parents in China seeking work in cities have left behind around 58 million rural children, mostly with relatives and without the involvement of the state. The present study examined caregivers’ and school personnel’s understandings of these school-age children’s needs through semi-structured interviews with 23 kin caregivers and five school personnel in Shijiapu Town, Jilin Province, China. The central question that guided the whole study is: What are the needs of children in informal kinship care in rural Jilin Province, China? Interpretative Phenomenological Analysis was used to categorise and interpret the qualitative data. Based on participants’ constructions, this study developed a need model with eight themes. They are: (1) emotional needs and mental health, (2) relationships, (3) empowerment and agency, (4) safety, (5) education, (6) basic care, (7) physical health, and (8) personal development. These needs are grounded in the Chinese context, and therefore a good understanding of Chinese culture is essential to address them. The first four needs particularly capture children’s separations from their parents, and the rest are more general, and can be applied to most Chinese children. To meet the most important need for children left behind, namely education, these caregivers determined that others needs sometimes have to be compromised. Children left behind are a vulnerable group in contemporary rural China, and their diverse needs are attended to by several groups. This study found that as children’s closest kin while their parents are away, caregivers play a vital role in salving the children’s emotional loss. Caregivers’ love and familial obligations strongly motivate them to care for these children, and sensitivity to social stigma makes them strive to show their love and care to compensate for perceived differences between these children and their peers. Caregivers’ efforts to make children happy, however, were sometimes criticised by some school personnel, who see this as spoiling. The conflicting viewpoint between caregivers and school personnel indicate their different roles and perceptions in children’s lives, and the latter influence these children in a more authoritative way. Informal kinship care has several advantages of addressing children’s needs, especially their needs for emotional bonds with family. Community-based kin networks provide children with both emotional and material support. However, these advantages sometimes are restricted by caregivers’ child rearing capacity. Having developed a model of the needs of children left behind in China, this study suggests that caregivers, school personnel and government social services work in harmony to be child-centred and meet these children’s diverse needs. The unmet needs of children left behind mainly result from unbalanced development between urban and rural China, therefore, it is imperative to enhance state policies and programs that improve wellbeing for this growing part of China’s people.

Vision in water

The purpose of this study is to determine visual performance in water, including the influence of pupil size. The water en-vironment was simulated by placing a goggle filled with saline in front of eyes, with apertures placed at the front of the goggle. Correction factors were determined for the different magnification under this condition in order to to estimate vision in water. Experiments were conducted on letter visual acuity (7 participants), grating resolution (8 participants), and grating contrast sensitivity (1 participant). For letter acuity, mean loss in vision in water, compared to corrected vision in air, varied between 1.1 log minutes of arc resolution (logMAR) for a 1mm aperture to 2.2 logMAR for a 7mm aperture. The vision in minutes of arc was described well by a linear relationship with pupil size. For grating acuity, mean loss varied between 1.1 logMAR for a 2mm aperture to 1.2 logMAR for a 6mm aperture. Contrast sensitivity for a 2mm aperture dete-riorated as spatial frequency increased, with 2 log unit loss by 3 cycles/degree. Superimposed on this deterioration were depressions (notches) in sensitivity, with the first three notches occurring at 0.45, 0.8 and 1.3 cycles/degree with esti-mates for water of 0.39, 0.70 and 1.13 cycles/degree. In conclusion, vision in water is poor. It becomes worse as pupil size increases, but the effects are much more marked for letter targets than for grating targets.

Vision in water

Purpose: To determine visual performance in water, including the influence of pupil size. Method: The water environment was simulated by placing a goggle filled with saline in front of eyes, with apertures placed at the front of the goggle. Correction factors were determined for the different magnification under this condition to estimate vision in water. Experiments were conducted on letter visual acuity (7 participants), grating resolution (8 participants), and grating contrast sensitivity (1 participant). Results: For letter acuity, mean loss in vision in water, compared to corrected vision in air, varied between 1.1 log minutes of arc resolution (logMAR) for a 1mm aperture to 2.2 logMAR for a 7mm aperture. The vision in minutes of arc was described well by a linear relationship with pupil size. For grating acuity, mean loss varied between 1.1 logMAR for a 2mm aperture to 1.2 logMAR for a 6mm aperture. Contrast sensitivity for a 2mm aperture deteriorated as spatial frequency increased, with 2 log unit loss by 3 cycles/degree. Superimposed on this deterioration were depressions (notches) in sensitivity, with the first three notches occurring at 0.45, 0.8 and 1.3 cycles/degree and with estimates for water of 0.39, 0.70 and 1.13 cycles/degree. Conclusion: Vision in water is poor. It becomes worse as pupil size increases, but the effects are much more marked for letter targets than for grating targets.

Prevalence of risk factors for undiagnosed obstructive sleep apnoea is high in truck drivers on UK roads

Objectives To determine the prevalence of symptoms and risk factors of obstructive sleep apnoea (OSA) in truck drivers at a UK large truck stop. Methods Over a 5 day period, truck drivers completed a short questionnaire at a major UK ‘truck stop’. The questionnaire asked about OSA rist factors and symptoms, and included the Epworth Sleepiness Scale (ESS). Additionally, measurements of height, weight and collar size were taken. 148 truck drivers participated and within this random group the risk factors of OSA that were looked for were:men age over 40 y, obesity, parge neck circumference, smoking, high ESS and bed partner reporting snoring with witnessed apnoeas. Results Our sample were all men, with 82% aged over 40 y. 47% were obese (compared with 23% for UK men in general) and average neck circumference was 42 cm (compared with 38 cm for UK men in general – Martin et al 1997). 31% smoked (vs 21% for general population), and ESS averaged 2.1 points higher than expected for a healthy population (Johns et al 1997). Snoring was quite evident at 57% (compared wth 40% for men in general) and witnessed apnoeas were almost double (7%) compared with 3.8% given by Ohayon et al (1997) generally for men. Conclusion 8 key symptoms and risk factors of OSA have been found to be prevalent in a sample of truck drivers on UK roads, and to greater extent that for estimates in the general male population. Bed partners of truck drivers reporting witnessed apnoeas strongly suggests this group has a high potential for undiagnosed OSA. OSA sufferers are known to be at high risk of causing road traffi c accidents. This, together with the large size of trucks, then the potential for serious road crashes is great. Truck drivers, especially those who are obese, ought to be a high priority population for OSA screening.

Continuous positive air pressure treatment for obstructive sleep apnoea patients : effects on sleep quality and quantity as measured by actigraphy

Objectives Actigraphy can reliably assess sleep in healthy adults and be used to estimate total sleep time in suspected obstructive sleep apnoea (OSA) patients. We compared sleep quality for Continuous Positive Air Pressure (CPAP) treated OSA patients and controls, evaluating the impact of stopping CPAP for one night. Methods 11 men, aged 51–75 years (m = 65.6 years), compliant CPAP users, treated for 1–19 years (m = 7.8 years) wore Cambridge Neurotechnology Ltd actiwatches for one night while using CPAP and for one night sleeping without CPAP. A control group of 11 healthy men, aged 63–74 years (m = 64.1 years) slept normally whilst wearing an actiwatch. Subsequent daytime sleepiness was recorded using Karolinska sleepiness scores (KSS). Results Actimetry showed no significant differences between actual sleep time, sleep efficiency, sleep disturbance index or number of wake bouts when comparing OSA participants using CPAP, with controls; there was no difference in subsequent daytime sleepiness, control KSS = 4.21, OSA KSS = 4.17. Without CPAP there was no significant difference in sleep length or sleep onset latency compared with using CPAP, but there was a significant impact on sleep quality as shown by: increased sleep disturbance index from 7.9 to 13.8 [t(10) = 3.510, P < 0.05], decreased percent of actual sleep from 92.05% to 86.15% [t(10) = 3.51, P < 0.05], decreased sleep efficiency from 86.6% to 81% [t(10) = 2.204, P < 0.05] and increased number of wake bouts from 29 to 42.5 [t(10) = 3.877, P < 0.05]. Daytime sleepiness became significantly worse increasing from KSS 4.17 to 6.27 [t(10) = )4.96, P < 0.05]. Conclusion There was no disparity in sleep quality or KSS scores between CPAP treated OSA patients and healthy controls of a similar age. Treated OSA patients obtained quality sleep with no elevated day time sleepiness. However, cessation of treatment for one night caused sleep quality to deteriorate despite a comparable sleep time; the deterioration in sleep quality could explain the increase in daytime sleepiness. OSA patients need to know that even short-term noncompliance with CPAP treatment significantly impairs sleep quality, leading to excessive sleepiness during monotonous tasks such as driving. Actigraphy successfully identified nights of non-compliance in treated OSA patients; but did not differentiate between the sleep of CPAP treated OSA patients and healthy controls.

The effect of a supervised exercise training programme on sleep quality in recently discharged heart failure patients

Background Sleep disturbances, including insomnia and sleep-disordered breathing, are a common complaint in people with heart failure and impair well-being. Exercise training (ET) improves quality of life in stable heart failure patients. ET also improves sleep quality in healthy older patients, but there are no previous intervention studies in heart failure patients. Aim The aim of this study was to examine the impact of ET on sleep quality in patients recently discharged from hospital with heart failure. Methods This was a sub-study of a multisite randomised controlled trial. Participants with a heart failure hospitalisation were randomised within six weeks of discharge to a 12-week disease management programme including exercise advice (n=52) or to the same programme with twice weekly structured ET (n=54). ET consisted of two one-hour supervised aerobic and resistance training sessions, prescribed and advanced by an exercise specialist. The primary outcome was change in Pittsburgh Sleep Quality Index (PSQI) between randomisation and week 12. Results At randomisation, 45% of participants reported poor sleep (PSQI≥5). PSQI global score improved significantly more in the ET group than the control group (–1.5±3.7 vs 0.4±3.8, p=0.03). Improved sleep quality correlated with improved exercise capacity and reduced depressive symptoms, but not with changes in body mass index or resting heart rate. Conclusion Twelve weeks of twice-weekly supervised ET improved sleep quality in patients recently discharged from hospital with heart failure.

Feeding beliefs and practices of Chinese immigrant mothers : validation of a modified version of the child feeding questionnaire

The Child Feeding Questionnaire (CFQ) developed by Birch and colleagues (2001) is a widely used tool for measuring parental feeding beliefs, attitudes and practices. However, the appropriateness of the CFQ for use with Chinese populations is unknown. This study tested the construct validity of a novel Chinese version of the CFQ using confirmatory factor analysis (CFA). Participants included a convenience sample of 254 Chinese-Australian mothers of children aged 1-4 years. Prior to testing, the questionnaire was translated into Chinese using a translation-back-translation method, one item was re-worded to be culturally appropriate, a new item was added (monitoring), and five items that were not age-appropriate for the sample were removed. Based on previous literature, both a 7-factor and an 8-factor model were assessed via CFA. Results showed that the 8-factor model, which separated restriction and use of food rewards, improved the conceptual clarity of the constructs and provided a good fit to the data. Internal consistency of all eight factors was acceptable (Cronbach’s α: .60−.93). This modified 8-factor CFQ appears to be a linguistically and culturally appropriate instrument for assessing feeding beliefs and practices in Chinese-Australian mothers of young children.

Solar evaporator-collectors : analyses and applications

Taking into consideration of growing energy needs and concern for environmental degradation, clean and inexhaustible energy source, such as solar energy, is receiving greater attention for various applications. The use of solar energy system reduces pollution, waste and has little or no harmful effects on the environment. It is appreciated that this source of energy can be complementary rather than being competitive to conventional energy sources. In order to collect and harness energy from the sun, a solar collector is essential. A solar collector is basically a heat exchanger that transforms solar radiant energy into heat or thermal energy. Improvement of performance is essential for commercial acceptance of their use in such applications. Many studies have been undertaken on the enhancement of thermal performance of solar collectors, using diverse materials of various shapes, dimensions and layouts. In the literature, various collector designs have been proposed and tested with the objective of meeting these requirements [1-8]. Omer et al. [1] found the efficiency of a solar collector of about 70% in a solar assisted heat pump system. Traditional solar collectors are single phase collectors, in which the working fluid is either air or water. Different modifications are suggested and applied to improve the heat transfer between the absorber and working fluid in a collector. These modifications include the use of absorber with fins attached [2,3], corrugated absorber [4,5], matrix type absorber [6], V-groove solar air collector [7]. Karim et al. [8] approached a review of design and construction of three types (flat, vee-grooved, and finned) of air collectors. Two-phase collectors, on the other hand, have significant potential for continuous operation round the clock, when used in conjunction with a compressor, as found in a solar assisted heat-pump cycle.

The effects of exercise and adipose tissue lipolysis on plasma adiponectin concentration and adiponectin receptor expression in human skeletal muscle

Objective It has been suggested that adiponectin regulates plasma free fatty acid (FFA) clearance by stimulating FFA uptake and/or oxidation in muscle. We aimed to determine changes in plasma adiponectin concentration and adiponectin receptor 1 and 2 mRNA expression in skeletal muscle during and after prolonged exercise under normal, fasting conditions (high FFA trial; HFA) and following pharmacological inhibition of adipose tissue lipolysis (low FFA trial; LFA). Furthermore, we aimed to detect and locate adiponectin in skeletal muscle tissue. Methods Ten subjects performed two exercise trials (120 min at 50% VO2max). Indirect calorimetry was used to determine total fat oxidation rate. Plasma samples were collected at rest, during exercise and during post-exercise recovery to determine adiponectin, FFA and glycerol concentrations. Muscle biopsies were taken to determine adiponectin protein and adiponectin receptor 1 and 2 mRNA expression and to localise intramyocellular adiponectin. Results Basal plasma adiponectin concentrations averaged 6.57±0.7 and 6.63±0.8 mg/l in the HFA and LFA trials respectively, and did not change significantly during or after exercise. In the LFA trial, plasma FFA concentrations and total fat oxidation rates were substantially reduced. However, plasma adiponectin and muscle adiponectin receptor 1 and 2 mRNA expression did not differ between trials. Immunohistochemical staining of muscle cross-sections showed the presence of adiponectin in the sarcolemma of individual muscle fibres and within the interfibrillar arterioles. Conclusion Plasma adiponectin concentrations and adiponectin receptor 1 and 2 mRNA expression in muscle are not acutely regulated by changes in adipose tissue lipolysis and/or plasma FFA concentrations. Adiponectin is abundantly expressed in muscle, and, for the first time, it has been shown to be present in/on the sarcolemma of individual muscle fibres.

Machine learning for activity recognition : hip versus wrist data

Problem addressed Wrist-worn accelerometers are associated with greater compliance. However, validated algorithms for predicting activity type from wrist-worn accelerometer data are lacking. This study compared the activity recognition rates of an activity classifier trained on acceleration signal collected on the wrist and hip. Methodology 52 children and adolescents (mean age 13.7 +/- 3.1 year) completed 12 activity trials that were categorized into 7 activity classes: lying down, sitting, standing, walking, running, basketball, and dancing. During each trial, participants wore an ActiGraph GT3X+ tri-axial accelerometer on the right hip and the non-dominant wrist. Features were extracted from 10-s windows and inputted into a regularized logistic regression model using R (Glmnet + L1). Results Classification accuracy for the hip and wrist was 91.0% +/- 3.1% and 88.4% +/- 3.0%, respectively. The hip model exhibited excellent classification accuracy for sitting (91.3%), standing (95.8%), walking (95.8%), and running (96.8%); acceptable classification accuracy for lying down (88.3%) and basketball (81.9%); and modest accuracy for dance (64.1%). The wrist model exhibited excellent classification accuracy for sitting (93.0%), standing (91.7%), and walking (95.8%); acceptable classification accuracy for basketball (86.0%); and modest accuracy for running (78.8%), lying down (74.6%) and dance (69.4%). Potential Impact Both the hip and wrist algorithms achieved acceptable classification accuracy, allowing researchers to use either placement for activity recognition.

Use of physical activity self-management strategies by high school students

Teaching adolescents to use self-management strategies (SMS's) may be an effective approach to promoting lifelong physical activity (PA). However, the extent to which adolescents use SMS's and their impact on current PA have not been studied previously. The aims of this study were: 1) describe the prevalence of SMS use in adolescents; and 2) determine relationships between SMS use, PA self-efficacy, and PA participation. 197 students completed questionnaires measuring use of SMS's, self-efficacy, and PA behavior. The most prevalent SMS's (>30%) were thinking about the benefits of PA, making PA more enjoyable, choosing activities that are convenient, setting aside time to do PA, and setting goals to do PA. Less than 10% reported rewarding oneself for PA, writing planned activities in a book or calendar, and keeping charts of PA. SMS use was associated with increased self-efficacy (r = 0.47, P < .001) and higher levels of PA (r = 0.34 P < .001). A one unit difference in SMS scores was associated with a ~ 4-fold increase in the probability of being active (OR = 3.7, 95% CI = 1.8-7.4). Although strongly associated with PA, a relatively small percentage of adolescents routinely use SMS's.

Effects of different surfaces on the perception of prey-generated noise by the Indian false vampire bat Megaderma lyra.

The low- and high-frequency components of a rustling sound, created when prey (freshly killed frog) was jerkily pulled on dry and wet sandy floors and asbestos, were recorded and played back to individual Indian false vampire bats (Megaderma lyra). Megaderma lyra responded with flight toward the speakers and captured dead frogs, that were kept as reward. The spectral peaks were at 8.6, 7.1 and 6.8 kHz for the low-frequency components of the sounds created at the dry, asbestos and wet floors, respectively. The spectral peaks for the high-frequency sounds created on the respective floors were at 36.8,27.2 and 23.3 kHz. The sound from the dry floor was more intense than that of from the other two substrata. Prey movements that generated sonic or ultrasonic sounds were both sufficient and necessary for the bats to detect and capture prey. The number of successful prey captures was significantly greater for the dry floor sound, especially to its high-frequency components. Bat-responses were low to the wet floor and moderate to the asbestos floor sounds. The bats did not respond to the sound of unrecorded parts of the tape. Even though the bats flew toward the speakers when the prey generated sounds were played back and captured the dead frogs we cannot rule out the possibility of M. lyra using echolocation to localize prey. However, the study indicates that prey that move on dry sandy floor are more vulnerable to predation by M. lyra.