MyMedR

Displaying publications 1 - 20 of 100 in total

Abstract:

Sort:

Fulltext Body image differences among Malay, Samoan, and Australian women

McDowell AJ, Bond M

Asia Pac J Clin Nutr, 2006;15(2):201-7.
PMID: 16672204

Comparisons of body attitudes and associated behaviours were undertaken using Malay, Samoan, and Australian female students. The general goal of the research was to determine the degree to which the observed pattern of attitudes and behaviours was attributable to culture. The specific analyses comprised an examination of group differences using standard measures that included the Body Attitudes Questionnaire, the Three-Factor Eating Questionnaire and detailed questions concerning the use of diet and exercise as weight control strategies. The main findings concerned a number of cultural differences, particularly in relation to diet and exercise, that were evident even with the effect of body mass index held constant. These results are interpreted in terms of the efficacy of entrenched cultural beliefs in protecting against introduced, more dominant, cultural values. The Australian sample exhibited the most negative body image, although there was some evidence that Malays and Samoans were influenced by Western ideals of weight and shape. It is proposed that to fully understand the differential meaning of negative body image across cultures and the potential impact of westernisation, both within-group and between-group differences in body size need to be acknowledged.
Fulltext Take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo (Galeopterus variegatus)

Byrnes G, Lim NT, Spence AJ

Proc Biol Sci, 2008 May 7;275(1638):1007-13.
PMID: 18252673 DOI: 10.1098/rspb.2007.1684

Arboreal animals negotiate a highly three-dimensional world that is discontinuous on many spatial scales. As the scale of substrate discontinuity increases, many arboreal animals rely on leaping or gliding locomotion between distant supports. In order to successfully move through their habitat, gliding animals must actively modulate both propulsive and aerodynamic forces. Here we examined the take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo (Galeopterus variegatus) using a custom-designed three-dimensional accelerometry system. We found that colugos increase the propulsive impulse to affect longer glides. However, we also found that landing forces are negatively associated with glide distance. Landing forces decrease rapidly as glide distance increases from the shortest glides, then level off, suggesting that the ability to reorient the aerodynamic forces prior to landing is an important mechanism to reduce velocity and thus landing forces. This ability to substantially alter the aerodynamic forces acting on the patagial wing in order to reorient the body is a key to the transition between leaping and gliding and allows gliding mammals to travel long distances between trees with reduced risk of injury. Longer glides may increase the access to distributed resources and reduce the exposure to predators in the canopy or on the forest floor.
Great apes: Fresh strategies to save orangutans

Marshall AJ, Wich S, Ancrenaz M

Nature, 2016 Jul 28;535(7613):493.
PMID: 27466115 DOI: 10.1038/535493a
Effects of action observation on corticospinal excitability: Muscle specificity, direction, and timing of the mirror response

Naish KR, Houston-Price C, Bremner AJ, Holmes NP

Neuropsychologia, 2014 11;64:331-48.
PMID: 25281883 DOI: 10.1016/j.neuropsychologia.2014.09.034

Many human behaviours and pathologies have been attributed to the putative mirror neuron system, a neural system that is active during both the observation and execution of actions. While there are now a very large number of papers on the mirror neuron system, variations in the methods and analyses employed by researchers mean that the basic characteristics of the mirror response are not clear. This review focuses on three important aspects of the mirror response, as measured by modulations in corticospinal excitability: (1) muscle specificity; (2) direction; and (3) timing of modulation. We focus mainly on electromyographic (EMG) data gathered following single-pulse transcranial magnetic stimulation (TMS), because this method provides precise information regarding these three aspects of the response. Data from paired-pulse TMS paradigms and peripheral nerve stimulation (PNS) are also considered when we discuss the possible mechanisms underlying the mirror response. In this systematic review of the literature, we examine the findings of 85 TMS and PNS studies of the human mirror response, and consider the limitations and advantages of the different methodological approaches these have adopted in relation to discrepancies between their findings. We conclude by proposing a testable model of how action observation modulates corticospinal excitability in humans. Specifically, we propose that action observation elicits an early, non-specific facilitation of corticospinal excitability (at around 90ms from action onset), followed by a later modulation of activity specific to the muscles involved in the observed action (from around 200ms). Testing this model will greatly advance our understanding of the mirror mechanism and provide a more stable grounding on which to base inferences about its role in human behaviour.
Fulltext The allometry of coarse root biomass: log-transformed linear regression or nonlinear regression?

Lai J, Yang B, Lin D, Kerkhoff AJ, Ma K

PLoS One, 2013;8(10):e77007.
PMID: 24116197 DOI: 10.1371/journal.pone.0077007

Precise estimation of root biomass is important for understanding carbon stocks and dynamics in forests. Traditionally, biomass estimates are based on allometric scaling relationships between stem diameter and coarse root biomass calculated using linear regression (LR) on log-transformed data. Recently, it has been suggested that nonlinear regression (NLR) is a preferable fitting method for scaling relationships. But while this claim has been contested on both theoretical and empirical grounds, and statistical methods have been developed to aid in choosing between the two methods in particular cases, few studies have examined the ramifications of erroneously applying NLR. Here, we use direct measurements of 159 trees belonging to three locally dominant species in east China to compare the LR and NLR models of diameter-root biomass allometry. We then contrast model predictions by estimating stand coarse root biomass based on census data from the nearby 24-ha Gutianshan forest plot and by testing the ability of the models to predict known root biomass values measured on multiple tropical species at the Pasoh Forest Reserve in Malaysia. Based on likelihood estimates for model error distributions, as well as the accuracy of extrapolative predictions, we find that LR on log-transformed data is superior to NLR for fitting diameter-root biomass scaling models. More importantly, inappropriately using NLR leads to grossly inaccurate stand biomass estimates, especially for stands dominated by smaller trees.
Not by science alone: why orangutan conservationists must think outside the box

Meijaard E, Wich S, Ancrenaz M, Marshall AJ

Ann N Y Acad Sci, 2012 Feb;1249:29-44.
PMID: 22175247 DOI: 10.1111/j.1749-6632.2011.06288.x

Orangutan survival is threatened by habitat loss and illegal killing. Most wild populations will disappear over the next few decades unless threats are abated. Saving orangutans is ultimately in the hands of the governments and people of Indonesia and Malaysia, which need to ensure that habitats of viable orangutan populations are protected from deforestation and well managed to ensure no hunting takes place. Companies working in orangutan habitat also have to play a much bigger role in habitat management. Although the major problems and the direct actions required to solve them-reducing forest loss and hunting-have been known for decades, orangutan populations continue to decline. Orangutan populations in Sumatra and Borneo have declined by between 2,280 and 5,250 orangutans annually over the past 25 years. As the total current population for the two species is some 60,000 animals in an area of about 90,000 km(2) , there is not much time left to make conservation efforts truly effective. Our review discusses what has and has not worked in conservation to guide future conservation efforts.
Fulltext Gliding saves time but not energy in Malayan colugos

Byrnes G, Libby T, Lim NT, Spence AJ

J Exp Biol, 2011 Aug 15;214(Pt 16):2690-6.
PMID: 21795564 DOI: 10.1242/jeb.052993

Gliding is thought to be an economical form of locomotion. However, few data on the climbing and gliding of free-ranging gliding mammals are available. This study employed an animal-borne three-dimensional acceleration data-logging system to collect continuous data on the climbing and gliding of free-ranging Malayan colugos, Galeopterus variegatus. We combined these movement data with empirical estimates of the metabolic costs to move horizontally or vertically to test this long-standing hypothesis by determining whether the metabolic cost to climb to sufficient height to glide a given distance was less than the cost to move an equivalent distance horizontally through the canopy. On average, colugos climb a short distance to initiate glides. However, due to the high energetic cost of climbing, gliding is more energetically costly to move a given horizontal distance than would be predicted for an animal travelling the same distance through the canopy. Furthermore, because colugos spend a small fraction of their time engaged in locomotor activity, the high costs have little effect on their overall energy budget. As a result, the energetic economy hypothesis for the origins of gliding is not supported. It is likely that other ecologically relevant factors have played a greater role in the origins of gliding in colugos and other mammals.
Alterations in selected serum biochemistry values of free-ranging Bornean leopard cats (Prionailurus bengalensis borneoensis) captured by box traps

Nájera F, Hearn AJ, Ross J, Nathan S, Revuelta L

Vet Res Commun, 2014 Sep;38(3):265-9.
PMID: 24839119 DOI: 10.1007/s11259-014-9605-2

Box-traps for capturing wild cats are widely used by researchers since it is one of the most effective methods for trapping these species. Although they are extensively utilised, the effects on the physiology of trapped felids remain unclear. Researchers frequently make judgements regarding the safety of such capture devices by examination of external injuries but often fail to take into consideration other physiological parameters. To assess the effects of capture events on selected serum biochemistry values of free-ranging Bornean leopard cats (Prionailurus bengalensis borneoensis) six free-ranging leopard cats (four males, two females) were trapped by using box-traps in Sabah, Malaysian Borneo. Blood was collected by jugular venipucture after chemical immobilization with a mixture of tiletamine and zolazepam. Blood was analysed for 17 serum biochemistry parameters. The most consistent and significantly higher value found in both sexes was aspartate aminotransferase (AST), followed by high mean value of alanine aminotransferase (ALT). Both mean values exceeded the upper limit of the reference range for captive leopard cats. These results demonstrate that captured leopard cats by box-traps undergo physical exertion and consequently some type of muscle injury/damage. Researchers and wildlife managers should be aware of the physiological response of trapped felids when using box-traps. Devices that facilitate the prompt removal of leopard cats from the traps would be useful for researchers to avoid further damage while live trapping this species.
The relationship between safety climate and safety performance: A review

Syed-Yahya SNN, Idris MA, Noblet AJ

J Safety Res, 2022 Dec;83:105-118.
PMID: 36481002 DOI: 10.1016/j.jsr.2022.08.008

INTRODUCTION: Since its inception more than four decades ago, research on safety climate has been conducted in many industries. Subsequently, a plethora of systematic literature reviews on safety climate in various work environments has focused on research trends and measurement scales. Yet, despite these reviews, the overall picture of how safety climate influences performance is still not well understood. The current study reviews existing literature on safety climate, specifically how it affects safety performance.
METHOD: Literature searches were conducted using EBSCOhost and Web of Science databases in March 2021. We included English-language, peer-reviewed studies that reported the results of research done on safety climate and safety performance. We extracted data (contextual, theoretical, methodological and definition of safety performance) from these studies and were deductively analyzed and categorized into common themes.
RESULTS: One hundred and sixty-two safety climate studies were identified. We found that studies on safety climate-performance were conducted in 16 types of industries while 23 different theories explained the safety climate-performance relationship. The quantity and quality of variables and methods used varied considerably across the surveys. Safety climate is predominantly used as a predictor while safety-related behavior is the most common definition of safety performance among the articles we reviewed. Few papers from the current review were methodologically strong, suggesting that current evidence on the link between safety climate and safety performance still suffers from common method bias.
CONCLUSIONS: Although literature has provided evidence for the positive effect on safety performance via a strong safety climate, strong and convincing methods are still lacking and the causality of an improved safety climate still needs to be demonstrated.
PRACTICAL APPLICATIONS: The findings of the current review offer a better understanding of how employers can improve safety climate in the workplace in various settings.
Fulltext Investigating quorum-quenching marine bacilli as potential biocontrol agents for protection of shrimps against Early Mortality Syndrome (EMS)

Müller M, Spiers AJ, Tan A, Mujahid A

Sci Rep, 2023 Mar 12;13(1):4095.
PMID: 36907954 DOI: 10.1038/s41598-023-31197-4

Early Mortality Syndrome (EMS) has been a major problem for shrimp aquaculture in Southeast Asia due to its epizootic prevalence within the region since the first reported case in 2009. This study explores the application of halophilic marine bacilli isolated from coral mucus and their quorum-quenching abilities as potential biocontrol agents in aquaculture systems to combat the causative agent of EMS, Vibrio parahaemolyticus. N-acylhomoserine lactone (AHL)-degrading (AiiA) activity was first screened by PCR then confirmed by bio-reporter assay, and a combination of 16S rDNA sequence analysis and quantitative phenotype assays including biofilm-formation and temperature-growth responses were used to demonstrate diversity amongst these quorum-quenching isolates. Three phenotypically distinct strains showing notable potential were chosen to undergo co-cultivation as a method for strain improvement via long term exposure to the pathogenic V. parahaemolyticus. The novel approach taken led to significant improvements in antagonism and quorum quenching activities as compared to the ancestral wild-type strains and offers a potential solution as well as pathway to improve existing beneficial microbes for one of the most pressing issues in shrimp aquacultures worldwide.
Fulltext Key indicators for monitoring food system disruptions caused by the COVID-19 pandemic: Insights from Bangladesh towards effective response

Amjath-Babu TS, Krupnik TJ, Thilsted SH, McDonald AJ

Food Secur, 2020;12(4):761-768.
PMID: 32837652 DOI: 10.1007/s12571-020-01083-2

In the context of developing countries, early evidence suggests that the impacts of the COVID-19 pandemic on food production systems is complex, heterogenous, and dynamic. As such, robust monitoring of the impact of the health crisis and containment measures across agricultural value chains will likely prove vitally important. With Bangladesh as a case study, we discuss the building blocks of a comprehensive monitoring system for prioritizing and designing interventions that respond to food system disruptions from COVID-19 and preemptively avoid further cascading negative effects. We also highlight the need for parallel research that identifies pathways for enhancing information flow, analysis, and action to improve the efficiency and reliability of input and output value chains. In aggregate, this preliminary work highlights the building blocks of resilient food systems to external shocks such as COVID-19 pandemic in the context of developing nations. In doing so, we call attention to the importance of 'infection safe' agricultural input and output distribution logistics, extended social safety nets, adequate credit facilities, and innovative labor management tools alongside, appropriate farm mechanization. In addition, digital extension services, circular nutrient flows, enhanced storage facilities, as well as innovative and robust marketing mechanisms are required. These should be considered in parallel with effective international trade management policies and institutions as crucial supportive measures.
An overview of genetically modified crop governance, issues and challenges in Malaysia

Andrew J, Ismail NW, Djama M

J Sci Food Agric, 2018 Jan;98(1):12-17.
PMID: 28898466 DOI: 10.1002/jsfa.8666

The application of agricultural biotechnology attracts the interest of many stakeholders. Genetically modified (GM) crops, for example, have been rapidly increasing in production for the last 20 years. Despite their known benefits, GM crops also pose many concerns not only to human and animal health but also to the environment. Malaysia, in general, allows the use of GM technology applications but it has to come with precautionary and safety measures consistent with the international obligations and domestic legal frameworks. This paper provides an overview of GM crop technology from international and national context and explores the governance and issues surrounding this technology application in Malaysia. Basically, GM research activities in Malaysia are still at an early stage of research and development and most of the GM crops approved for release are limited for food, feed and processing purposes. Even though Malaysia has not planted any GM crops commercially, actions toward such a direction seem promising. Several issues concerning GM crops as discussed in this paper will become more complex as the number of GM crops and varieties commercialised globally increase and Malaysia starts to plant GM crops. © 2017 Society of Chemical Industry.
Dietary repletion with ω3 fatty acid or with COX inhibition reverses cognitive effects in F3 ω3 fatty-acid-deficient mice

Hafandi A, Begg DP, Premaratna SD, Sinclair AJ, Jois M, Weisinger RS

Comp. Med., 2014 Apr;64(2):106-9.
PMID: 24674584

Dietary deficiency of ω3 fatty acid during development leads to impaired cognitive function. However, the effects of multiple generations of ω3 fatty-acid deficiency on cognitive impairment remain unclear. In addition, we sought to test the hypothesis that the cognitive impairments of ω3 fatty-acid-deficient mice are mediated through the arachidonic acid-cyclooxygenase (COX) pathway. To address these issues, C57BL/6J mice were bred for 3 generations and fed diets either deficient (DEF) or sufficient (SUF) in ω3 fatty acids. At postnatal day 21, the F3 offspring remained on the dam's diet or were switched to the opposite diet, creating 4 groups. In addition, 2 groups that remained on the dam's diet were treated with a COX inhibitor. At 19 wk of age, spatial-recognition memory was tested on a Y-maze. Results showed that 16 wk of SUF diet reversed the cognitive impairment of F3 DEF mice. However, 16 wk of ω3 fatty-acid-deficient diet impaired the cognitive performance of the F3 SUF mice, which did not differ from that of the F3 DEF mice. These findings suggest that the cognitive deficits after multigenerational maintenance on ω3 fatty-acid-deficient diet are not any greater than are those after deficiency during a single generation. In addition, treatment with a COX inhibitor prevented spatial-recognition deficits in F3 DEF mice. Therefore, cognitive impairment due to dietary ω3 fatty-acid deficiency appears to be mediated by the arachidonic acid-COX pathway and can be prevented by 16 wk of dietary repletion with ω3 fatty acids or COX inhibition.
The expression of Bcl-2 by proliferating cells varies in different categories of B-cell lymphoma

Masir N, Jones M, Lee AM, Goff LK, Clear AJ, Lister A, et al.

Histopathology, 2010 Apr;56(5):617-26.
PMID: 20459572 DOI: 10.1111/j.1365-2559.2010.03524.x

To investigate the relationship between Bcl-2 protein expression and cell proliferation at single-cell level in B-cell lymphomas using double-labelling techniques.
Fulltext An Asian regional analysis of cost-effectiveness of early irbesartan treatment versus conventional antihypertensive, late amlodipine, and late irbesartan treatments in patients with type 2 diabetes, hypertension, and nephropathy

Annemans L, Demarteau N, Hu S, Lee TJ, Morad Z, Supaporn T, et al.

Value Health, 2008 May-Jun;11(3):354-64.
PMID: 17888064 DOI: 10.1111/j.1524-4733.2007.00250.x

OBJECTIVE: The prevalence of type 2 diabetes, often leading to diabetic nephropathy, has increased globally, especially in Asia. Irbesartan treatment delays the progression of kidney disease at the early (microalbuminuria) and late (proteinuria) stages of nephropathy in hypertensive type 2 diabetics. This treatment has proven to be cost-effective in Western countries. This study assessed the cost-effectiveness of early irbesartan treatment in Asian settings.
METHODS: An existing lifetime model was reprogrammed in Microsoft Excel to compare irbesartan started at an early stage to irbesartan or amlodipine started at a late stage, and standard treatments from a health-care perspective in China, Malaysia, Thailand, South Korea, and Taiwan. The main effectiveness parameters were incidences of end-stage renal disease, time in dialysis, and life expectancy. All costs were converted to 2004 US$ using official purchasing power parity. Local data were obtained for costs, transplantation,dialysis, and mortality rates. Probabilities regarding disease progression after treatment with the investigated drugs were extracted from two published clinical trials. A probabilistic sensitivity analysis was performed.
RESULTS: Early use of irbesartan yielded the largest clinical and economic benefits reducing need for dialysis by 61% to 63% versus the standard treatment, total costs by 9% (Thailand) to 42% (Taiwan), and increasing life expectancy by 0.31 to 0.48 years. Early irbesartan had a 66% (Thailand) to 95% (Taiwan) probability of being dominant over late irbesartan.
CONCLUSION: Although the absolute results varied in different settings, reflecting differences in epidemiology, management, and costs, early irbesartan treatment was a cost-effective alternative in the Asian settings.
Interspecific interactions between primates, birds, bats, and squirrels may affect community composition on Borneo

Beaudrot L, Struebig MJ, Meijaard E, van Balen S, Husson S, Young CF, et al.

Am J Primatol, 2013 Feb;75(2):170-85.
PMID: 23184656 DOI: 10.1002/ajp.22095

For several decades, primatologists have been interested in understanding how sympatric primate species are able to coexist. Most of our understanding of primate community ecology derives from the assumption that these animals interact predominantly with other primates. In this study, we investigate to what extent multiple community assembly hypotheses consistent with this assumption are supported when tested with communities of primates in isolation versus with communities of primates, birds, bats, and squirrels together. We focus on vertebrate communities on the island of Borneo, where we examine the determinants of presence or absence of species, and how these communities are structured. We test for checkerboard distributions, guild proportionality, and Fox's assembly rule for favored states, and predict that statistical signals reflecting interactions between ecologically similar species will be stronger when nonprimate taxa are included in analyses. We found strong support for checkerboard distributions in several communities, particularly when taxonomic groups were combined, and after controlling for habitat effects. We found evidence of guild proportionality in some communities, but did not find significant support for Fox's assembly rule in any of the communities examined. These results demonstrate the presence of vertebrate community structure that is ecologically determined rather than randomly generated, which is a finding consistent with the interpretation that interactions within and between these taxonomic groups may have shaped species composition in these communities. This research highlights the importance of considering the broader vertebrate communities with which primates co-occur, and so we urge primatologists to explicitly consider nonprimate taxa in the study of primate ecology.
Fulltext The First Estimates of Marbled Cat Pardofelis marmorata Population Density from Bornean Primary and Selectively Logged Forest

Hearn AJ, Ross J, Bernard H, Bakar SA, Hunter LT, Macdonald DW

PLoS One, 2016;11(3):e0151046.
PMID: 27007219 DOI: 10.1371/journal.pone.0151046

The marbled cat Pardofelis marmorata is a poorly known wild cat that has a broad distribution across much of the Indomalayan ecorealm. This felid is thought to exist at low population densities throughout its range, yet no estimates of its abundance exist, hampering assessment of its conservation status. To investigate the distribution and abundance of marbled cats we conducted intensive, felid-focused camera trap surveys of eight forest areas and two oil palm plantations in Sabah, Malaysian Borneo. Study sites were broadly representative of the range of habitat types and the gradient of anthropogenic disturbance and fragmentation present in contemporary Sabah. We recorded marbled cats from all forest study areas apart from a small, relatively isolated forest patch, although photographic detection frequency varied greatly between areas. No marbled cats were recorded within the plantations, but a single individual was recorded walking along the forest/plantation boundary. We collected sufficient numbers of marbled cat photographic captures at three study areas to permit density estimation based on spatially explicit capture-recapture analyses. Estimates of population density from the primary, lowland Danum Valley Conservation Area and primary upland, Tawau Hills Park, were 19.57 (SD: 8.36) and 7.10 (SD: 1.90) individuals per 100 km2, respectively, and the selectively logged, lowland Tabin Wildlife Reserve yielded an estimated density of 10.45 (SD: 3.38) individuals per 100 km2. The low detection frequencies recorded in our other survey sites and from published studies elsewhere in its range, and the absence of previous density estimates for this felid suggest that our density estimates may be from the higher end of their abundance spectrum. We provide recommendations for future marbled cat survey approaches.
Hematological and blood chemistry values in captive Japanese macaques (Macaca fuscata fuscata)

Miyabe-Nishiwaki T, MacIntosh AJJ, Kaneko A, Morimoto M, Suzuki J, Akari H, et al.

J Med Primatol, 2019 Dec;48(6):338-350.
PMID: 31418873 DOI: 10.1111/jmp.12434

BACKGROUND: Biological information about captive Japanese macaques, including hematology and blood chemistry, is still lacking despite the fact that ethological and ecological data have accumulated during decades of field research.
METHODS: Hematological (511 examinations of 280 Japanese macaques) and blood chemistry data (between 33 and 284 examinations from between 29 and 257 individual macaques) in clinically healthy, simian retrovirus-free Japanese macaques tested between 2009 and 2013 were reviewed.
RESULTS AND CONCLUSIONS: Specific hematological and blood chemistry data for Japanese macaques without clinical signs of disease were provided in this study. Averages presented can be used as hematological parameters for Japanese macaques. Some differences between Japanese macaques and other closely related macaque species were found. Some parameters varied according to macaque age and sex, as well as regional origin. The data in this study will provide useful clinical indices for Japanese macaques in captive and similar conditions.
Parkinson's disease and the gastrointestinal microbiome

Lubomski M, Tan AH, Lim SY, Holmes AJ, Davis RL, Sue CM

J Neurol, 2020 Sep;267(9):2507-2523.
PMID: 31041582 DOI: 10.1007/s00415-019-09320-1

Recently, there has been a surge in awareness of the gastrointestinal microbiome (GM) and its role in health and disease. Of particular note is an association between the GM and Parkinson's disease (PD) and the realisation that the GM can act via a complex bidirectional communication between the gut and the brain. Compelling evidence suggests that a shift in GM composition may play an important role in the pathogenesis of PD by facilitating the characteristic ascending neurodegenerative spread of α-synuclein aggregates from the enteric nervous system to the brain. Here, we review evidence linking GM changes with PD, highlighting mechanisms supportive of pathological α-synuclein spread and intestinal inflammation in PD. We summarise existing patterns and correlations seen in clinical studies of the GM in PD, together with the impacts of non-motor symptoms, medications, lifestyle, diet and ageing on the GM. Roles of GM modulating therapies including probiotics and faecal microbiota transplantation are discussed. Encouragingly, alterations in the GM have repeatedly been observed in PD, supporting a biological link and highlighting it as a potential therapeutic target.
Fulltext Initial testing of a pixelated silicon detector prototype in proton therapy

Wroe AJ, McAuley G, Teran AV, Wong J, Petasecca M, Lerch M, et al.

J Appl Clin Med Phys, 2017 Sep;18(5):315-324.
PMID: 28719019 DOI: 10.1002/acm2.12120

As technology continues to develop, external beam radiation therapy is being employed, with increased conformity, to treat smaller targets. As this occurs, the dosimetry methods and tools employed to quantify these fields for treatment also have to evolve to provide increased spatial resolution. The team at the University of Wollongong has developed a pixelated silicon detector prototype known as the dose magnifying glass (DMG) for real-time small-field metrology. This device has been tested in photon fields and IMRT. The purpose of this work was to conduct the initial performance tests with proton radiation, using beam energies and modulations typically associated with proton radiosurgery. Depth dose and lateral beam profiles were measured and compared with those collected using a PTW parallel-plate ionization chamber, a PTW proton-specific dosimetry diode, EBT3 Gafchromic film, and Monte Carlo simulations. Measurements of the depth dose profile yielded good agreement when compared with Monte Carlo, diode and ionization chamber. Bragg peak location was measured accurately by the DMG by scanning along the depth dose profile, and the relative response of the DMG at the center of modulation was within 2.5% of that for the PTW dosimetry diode for all energy and modulation combinations tested. Real-time beam profile measurements of a 5 mm 127 MeV proton beam also yielded FWHM and FW90 within ±1 channel (0.1 mm) of the Monte Carlo and EBT3 film data across all depths tested. The DMG tested here proved to be a useful device at measuring depth dose profiles in proton therapy with a stable response across the entire proton spread-out Bragg peak. In addition, the linear array of small sensitive volumes allowed for accurate point and high spatial resolution one-dimensional profile measurements of small radiation fields in real time to be completed with minimal impact from partial volume averaging.

Filters

Please provide feedback to Administrator (afdal@afpm.org.my)

External Links