Displaying publications 1 - 20 of 24 in total

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  1. Pillai D, Sheppard E, Mitchell P
    PLoS One, 2012;7(11):e49859.
    PMID: 23226227 DOI: 10.1371/journal.pone.0049859
    Are we able to infer what happened to a person from a brief sample of his/her behaviour? It has been proposed that mentalising skills can be used to retrodict as well as predict behaviour, that is, to determine what mental states of a target have already occurred. The current study aimed to develop a paradigm to explore these processes, which takes into account the intricacies of real-life situations in which reasoning about mental states, as embodied in behaviour, may be utilised. A novel task was devised which involved observing subtle and naturalistic reactions of others in order to determine the event that had previously taken place. Thirty-five participants viewed videos of real individuals reacting to the researcher behaving in one of four possible ways, and were asked to judge which of the four 'scenarios' they thought the individual was responding to. Their eye movements were recorded to establish the visual strategies used. Participants were able to deduce successfully from a small sample of behaviour which scenario had previously occurred. Surprisingly, looking at the eye region was associated with poorer identification of the scenarios, and eye movement strategy varied depending on the event experienced by the person in the video. This suggests people flexibly deploy their attention using a retrodictive mindreading process to infer events.
  2. Sheppard E, Pillai D, Wong GT, Ropar D, Mitchell P
    J Autism Dev Disord, 2016 Apr;46(4):1247-54.
    PMID: 26603886 DOI: 10.1007/s10803-015-2662-8
    How well can neurotypical adults' interpret mental states in people with ASD? 'Targets' (ASD and neurotypical) reactions to four events were video-recorded then shown to neurotypical participants whose task was to identify which event the target had experienced. In study 1 participants were more successful for neurotypical than ASD targets. In study 2, participants rated ASD targets equally expressive as neurotypical targets for three of the events, while in study 3 participants gave different verbal descriptions of the reactions of ASD and neurotypical targets. It thus seems people with ASD react differently but not less expressively to events. Because neurotypicals are ineffective in interpreting the behaviour of those with ASD, this could contribute to the social difficulties in ASD.
  3. Ramaiah SS, Mitchell P, Dowling R, Yan B
    J Stroke Cerebrovasc Dis, 2014 Mar;23(3):399-407.
    PMID: 23601372 DOI: 10.1016/j.jstrokecerebrovasdis.2013.03.012
    Evidence from recent randomized controlled studies comparing intra-arterial (IA) therapy with intravenous tissue plasminogen activator highlighted the mismatch between recanalization success and clinical outcomes in patients presenting with acute ischemic stroke. There is emerging interest in the impact of arterial collateralization, as determined by leptomeningeal anastomoses (LMAs), on the treatment outcomes of IA therapy. The system of LMA constitutes the secondary network of cerebral collateral circulation apart from the Circle of Willis. Both anatomic and angiographic studies confirmed significant interindividual variability in LMA. This review aims to outline the current understanding of arterial collateralization and its impact on outcomes after IA therapy for acute ischemic stroke, underpinning the possible role of arterial collateralization assessment as a selection tool for patients most likely to benefit from IA therapy.
  4. Misra S, Khor GL, Mitchell P, Haque S, Benton D
    BMC Pediatr, 2015;15:79.
    PMID: 26174581 DOI: 10.1186/s12887-015-0393-9
    BACKGROUND: Sleep is important for children as it directly impacts their mental and physical development. Sleep is not only influenced by the timing but also the macronutrient (carbohydrate and protein) content of meals. Glycaemic index (GI) and glycaemic load (GL) describe the quality of carbohydrates in a food and the burden of these foods on the body's blood glucose response. Diets with a high GI/GL may increase the risk of developing obesity and type 2 diabetes mellitus in adulthood. The present study is piloted to evaluate the short-term impact of milk products with differing glycaemic properties on the sleep patterns of toddlers.
    METHODS: Toddlers were recruited from various day care centres. Informed consent was obtained from both the mothers and the centres. A double-blind randomised controlled trial with a between-subjects design was adopted. The toddlers were randomised to either one of two types of milk with a differing GI ("Low" = 23 and "High = 65") for a period of 3.5 days. There were no other dietary restrictions imposed except that the enrolled child did not consume any other milk during the study period. The sleep patterns were recorded using a Phillips Actiwatch-2, which was worn on the wrist for 24 h over 4 days. The parameters used to measure the sleep pattern were sleep-onset latency (SOL), total sleep time (TST), wake after sleep onset (WASO) and sleep efficiency (SE).
    RESULTS: A total of 56 toddlers completed the study. The toddlers had a mean age of 19.9 +/- 4.3 months. There were no significant differences (p > 0.05) between the two GI groups for SOL, TST, WASO and SE at the end of the feeding period.
    CONCLUSIONS: Sleep patterns of toddlers on low-GI milk did not differ from those with high-GI milk consumed over a short period. Future studies should consider the glycaemic effects of other foods, along with milk with differing GI, consumed for a longer feeding duration.
    TRIAL REGISTRATION: ClinicalTrial.gov NCT01589003.
  5. Teoh Y, Wallis E, Stephen ID, Mitchell P
    Cognition, 2017 02;159:48-60.
    PMID: 27886521 DOI: 10.1016/j.cognition.2016.11.003
    Past research tells us that individuals can infer information about a target's emotional state and intentions from their facial expressions (Frith & Frith, 2012), a process known as mentalising. This extends to inferring the events that caused the facial reaction (e.g. Pillai, Sheppard, & Mitchell, 2012; Pillai et al., 2014), an ability known as retrodictive mindreading. Here, we enter new territory by investigating whether or not people (perceivers) can guess a target's social context by observing their response to stimuli. In Experiment 1, perceivers viewed targets' responses and were able to determine whether these targets were alone or observed by another person. In Experiment 2, another group of perceivers, without any knowledge of the social context or what the targets were watching, judged whether targets were hiding or exaggerating their facial expressions; and their judgments discriminated between conditions in which targets were observed and alone. Experiment 3 established that another group of perceivers' judgments of social context were associated with estimations of target expressivity to some degree. In Experiments 1 and 2, the eye movements of perceivers also varied between conditions in which targets were observed and alone. Perceivers were thus able to infer a target's social context from their visible response. The results demonstrate an ability to use other minds as a window onto a social context that could not be seen directly.
  6. Aliahmad B, Kumar DK, Hao H, Unnikrishnan P, Che Azemin MZ, Kawasaki R, et al.
    ScientificWorldJournal, 2014;2014:467462.
    PMID: 25485298 DOI: 10.1155/2014/467462
    Fractal dimensions (FDs) are frequently used for summarizing the complexity of retinal vascular. However, previous techniques on this topic were not zone specific. A new methodology to measure FD of a specific zone in retinal images has been developed and tested as a marker for stroke prediction. Higuchi's fractal dimension was measured in circumferential direction (FDC) with respect to optic disk (OD), in three concentric regions between OD boundary and 1.5 OD diameter from its margin. The significance of its association with future episode of stroke event was tested using the Blue Mountain Eye Study (BMES) database and compared against spectrum fractal dimension (SFD) and box-counting (BC) dimension. Kruskal-Wallis analysis revealed FDC as a better predictor of stroke (H = 5.80, P = 0.016, α = 0.05) compared with SFD (H = 0.51, P = 0.475, α = 0.05) and BC (H = 0.41, P = 0.520, α = 0.05) with overall lower median value for the cases compared to the control group. This work has shown that there is a significant association between zone specific FDC of eye fundus images with future episode of stroke while this difference is not significant when other FD methods are employed.
  7. Cheung CM, Li X, Cheng CY, Zheng Y, Mitchell P, Wang JJ, et al.
    Ophthalmology, 2014 Aug;121(8):1598-603.
    PMID: 24661862 DOI: 10.1016/j.ophtha.2014.02.004
    To describe the prevalence and risk factors for age-related macular degeneration (AMD) in a multiethnic Asian cohort of Chinese, Malay, and Indian persons.
  8. Pillai D, Sheppard E, Ropar D, Marsh L, Pearson A, Mitchell P
    J Autism Dev Disord, 2014 Oct;44(10):2430-9.
    PMID: 24710812 DOI: 10.1007/s10803-014-2106-x
    It has been proposed that mentalising involves retrodicting as well as predicting behaviour, by inferring previous mental states of a target. This study investigated whether retrodiction is impaired in individuals with autism spectrum disorders (ASD). Participants watched videos of real people reacting to the researcher behaving in one of four possible ways. Their task was to decide which of these four "scenarios" each person responded to. Participants' eye movements were recorded. Participants with ASD were poorer than comparison participants at identifying the scenario to which people in the videos were responding. There were no group differences in time spent looking at the eyes or mouth. The findings imply those with ASD are impaired in using mentalising skills for retrodiction.
  9. Sun C, Liew G, Wang JJ, Mitchell P, Saw SM, Aung T, et al.
    Invest Ophthalmol Vis Sci, 2008 May;49(5):1784-90.
    PMID: 18436813 DOI: 10.1167/iovs.07-1450
    To describe the relationship of retinal vascular caliber with cardiovascular risk factors in an Asian population.
  10. Koh V, Cheung CY, Wong WL, Cheung CM, Wang JJ, Mitchell P, et al.
    Invest Ophthalmol Vis Sci, 2012 Feb;53(2):1018-22.
    PMID: 22247478 DOI: 10.1167/iovs.11-8557
    To describe the prevalence of epiretinal membrane (ERM) and its risk factors in an Indian population and compare the findings with other populations.
  11. Cheung N, Lim L, Wang JJ, Islam FM, Mitchell P, Saw SM, et al.
    Am J Ophthalmol, 2008 Oct;146(4):620-4.
    PMID: 18639861 DOI: 10.1016/j.ajo.2008.05.033
    To examine the prevalence and risk factors of retinal arteriolar emboli, a risk predictor of stroke, in an Asian population.
  12. Amerasinghe N, Wong TY, Wong WL, Mitchell P, Shen SY, Loon SC, et al.
    Arch. Ophthalmol., 2008 Aug;126(8):1101-8.
    PMID: 18695105 DOI: 10.1001/archopht.126.8.1101
    To describe the distribution and determinants of the optic cup to disc ratio (CDR) in Malay adults in Singapore.
  13. Tan AG, Tham YC, Chee ML, Mitchell P, Cumming RG, Sabanayagam C, et al.
    Clin Exp Ophthalmol, 2020 07;48(5):580-592.
    PMID: 32255547 DOI: 10.1111/ceo.13757
    IMPORTANCE: Long-term data on age-related cataract, a leading cause of blindness and visual impairment, is scarce in Asian populations.

    BACKGROUND: We report the 6-year incidence and progression of age-related cataract and associated risk factors in Malay adults living in Singapore.

    DESIGN: Population-based cohort study.

    PARTICIPANTS: A total of 3280 Malays aged 40+ years participated in baseline examinations of the Singapore Malay Eye Study (2004-2006). Six years later, 1901 (72.1% of eligible) baseline participants were re-examined.

    METHODS: Cataract was assessed using lens photos, taken during eye examinations, following the Wisconsin Cataract Grading System.

    MAIN OUTCOMES AND MEASURES: Incidence and progression of cortical, nuclear and posterior subcapsular (PSC) cataract. Poisson regression models and generalized estimating equations models (with Poisson link) were used to assess factors associated with cataract incidence and progression, respectively, adjusting for age, sex and other risk factors.

    RESULTS: Age-adjusted 6-year incidence of cortical, nuclear and PSC cataract was 14.1%, 13.6% and 8.7%, respectively, and was strongly age-related (P for trend

  14. Cheung CY, Lamoureux E, Ikram MK, Sasongko MB, Ding J, Zheng Y, et al.
    J Diabetes Sci Technol, 2012 May 01;6(3):595-605.
    PMID: 22768891 DOI: 10.1177/193229681200600315
    Purpose: Our purpose was to examine the relationship of retinal vascular parameters with diabetes and retinopathy in an older Asian population.

    Methods: Retinal photographs from participants of a population-based survey of Asian Malay persons aged 40-80 years were analyzed. Specific retinal vascular parameters (tortuosity, branching angle, fractal dimension, and caliber) were measured using a semiautomated computer-based program. Diabetes was defined as random plasma glucose ≥ 11.1 mmol/liter, the use of diabetes medication, or physician-diagnosed diabetes. Retinopathy signs were graded from photographs using the modified Airlie House classification system.

    Results: A total of 2735 persons were included in the study. Persons with diabetes (n = 594) were more likely to have straighter (less tortuous) arterioles and wider arteriolar and venular caliber than those without diabetes (n = 2141). Among subjects with diabetes, those with retinopathy had wider venular caliber than those without retinopathy (211.3 versus 204.9 mm, p = .001). Among nondiabetic subjects, however, those with retinopathy had more tortuous venules than those without retinopathy [5.19(×10(4)) versus 4.27(×10(4)), p < .001].

    Conclusions: Retinal vascular parameters varied by diabetes and retinopathy status in this older Asian cohort. Our findings suggest that subtle alterations in retinal vascular architecture are influenced by diabetes.
  15. Cheung CY, Tay WT, Mitchell P, Wang JJ, Hsu W, Lee ML, et al.
    J Hypertens, 2011 Jul;29(7):1380-91.
    PMID: 21558958 DOI: 10.1097/HJH.0b013e328347266c
    The present study examined the effects of blood pressure on a spectrum of quantitative and qualitative retinal microvascular signs.
  16. Cheung CMG, Ong PG, Neelam K, Tan PC, Shi Y, Mitchell P, et al.
    Ophthalmology, 2017 09;124(9):1305-1313.
    PMID: 28501376 DOI: 10.1016/j.ophtha.2017.03.056
    PURPOSE: To determine the 6-year incidence of early and late age-related macular degeneration (AMD) in a Singaporean Malay population and to validate the Age-Related Eye Disease Study (AREDS) simplified severity scale in Asians.

    DESIGN: Prospective, population cohort study.

    PARTICIPANTS: The Singapore Malay Eye Study baseline participants (age, ≥40 years; 2006-2008) were followed up in 2011 through 2013, and 1901 of 3280 of eligible participants (72.1%) took part.

    METHODS: Fundus photographs were graded using the Wisconsin AMD grading system.

    MAIN OUTCOME MEASURES: Incidence of early and late AMD.

    RESULTS: Gradable fundus photographs were available for 1809 participants who attended both baseline and 6-year follow-up examinations. The age-standardized incidences of early and late AMD were 5.89% (95% confidence interval [CI], 4.81-7.16) and 0.76% (95% CI, 0.42-1.29), respectively. The 5-year age-standardized incidence of early AMD (calculated based on the 6-year incidence) was lower in our population (5.58%; 95% CI, 4.43-7.01) compared with the Beaver Dam Eye Study population (8.19%). The incidence of late AMD in our population was similar to that of the Beaver Dam Eye Study population (0.98% [95% CI, 0.49-1.86] vs. 0.91%), the Blue Mountains Eye Study population (1.10% [95% CI, 0.52-9.56] vs. 1.10%), and the Hisayama Study population (1.09% [95% CI, 0.54-4.25] vs. 0.84%). The incidence of late AMD increased markedly with increasing baseline AREDS score (step 0, 0.23%; step 4, 9.09%).

    CONCLUSIONS: This study documented the incidence of early and late AMD in a Malay population. The AREDS simplified severity scale is useful in predicting the risk of late AMD development in Asians.

  17. Lee JK, Chee WS, Foo SH, Lee VK, Sallehuddin H, Khor HM, et al.
    Osteoporos Int, 2023 Nov;34(11):1837-1850.
    PMID: 37430004 DOI: 10.1007/s00198-023-06841-4
    PURPOSE: Vitamin D deficiency and insufficiency is common among populations globally, and in Asia and Malaysia. The purpose of this Position Paper is to propose recommendations for both clinicians and non-clinicians to promote vitamin D sufficiency in Malaysian adults. Formation of a national multisector, multidisciplinary alliance is also proposed to progress initiatives relating to safe sun exposure, adequate vitamin D intake through food fortification, and vitamin D supplementation for high-risk groups.

    METHODS: Literature reviews were undertaken to inform summaries of the following: vitamin D status globally and in Asian and Malaysian populations, vitamin D status among individuals with common medical conditions, and current recommendations to achieve vitamin D sufficiency through sun exposure, food intake and supplementation. Recommendations were based on the findings of the literature reviews, recent European guidance on vitamin D supplementation, the 2018 road map for action on vitamin D in low- and middle-income countries, and research recommendations proposed by the Malaysian Ministry of Health in 2017.

    RESULTS: Recommendations on assessment of vitamin D in the adult Malaysian population include using serum or plasma 25-hydroxyvitamin D concentration as a biomarker, widespread participation by Malaysian laboratories in the Vitamin D Standardization Program, adoption of the US Endocrine Society definitions of vitamin D deficiency and insufficiency, and development of a comprehensive nationwide vitamin D status study. Specific high-risk groups are identified for vitamin D assessment and recommendations relating to loading doses and ongoing management are also made.

    CONCLUSION: This Position Paper provides individual clinicians and national stakeholder organisations with clear recommendations to achieve vitamin D sufficiency in the adult population of Malaysia.

  18. Chaikitmongkol V, Sagong M, Lai TYY, Tan GSW, Ngah NF, Ohji M, et al.
    Asia Pac J Ophthalmol (Phila), 2021 Nov 24;10(6):507-518.
    PMID: 34839342 DOI: 10.1097/APO.0000000000000445
    PURPOSE: Review and provide consensus recommendations on use of treat-and-extend (T&E) regimens for neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV) management with relevance for clinicians in the Asia-Pacific region.

    METHODS: A systematic search of MEDLINE, EMBASE, and Cochrane databases, and abstract databases of the Asia-Pacific Vitreo-retina Society, European Society of Retina Specialists, American Academy of Ophthalmology, and Controversies in Ophthalmology: Asia-Australia congresses, was conducted to assess evidence for T&E regimens in nAMD. Only studies with ≥100 study eyes were included. An expert panel reviewed the results and key factors potentially influencing the use of T&E regimens in nAMD and PCV, and subsequently formed consensus recommendations for their application in the Asia-Pacific region.

    RESULTS: Twenty-seven studies were included. Studies demonstrated that T&E regimens with aflibercept, ranibizumab, or bevacizumab in nAMD, and with aflibercept in PCV, were efficacious and safe. The recommendation for T&E is, after ≥3 consecutive monthly loading doses, treatment intervals can be extended by 2 to 4 weeks up to 12 to 16 weeks. When disease activity recurs, the recommendation is to reinject and shorten intervals by 2 to 4 weeks until fluid resolution, after which treatment intervals can again be extended. Intraretinal fluid should be treated until resolved; however, persistent minimal subretinal fluid after consecutive treatments may be tolerated with treatment intervals maintained or extended if the clinical condition is stable.

    CONCLUSIONS: T&E regimens are efficacious and safe for nAMD and PCV, can reduce the number of visits, and minimize the overall burden for clinicians and patients.

  19. Chandran M, Mitchell PJ, Amphansap T, Bhadada SK, Chadha M, Chan DC, et al.
    Osteoporos Int, 2021 Jul;32(7):1249-1275.
    PMID: 33502559 DOI: 10.1007/s00198-020-05742-0
    Guidelines for doctors managing osteoporosis in the Asia-Pacific region vary widely. We compared 18 guidelines for similarities and differences in five key areas. We then used a structured consensus process to develop clinical standards of care for the diagnosis and management of osteoporosis and for improving the quality of care.

    PURPOSE: Minimum clinical standards for assessment and management of osteoporosis are needed in the Asia-Pacific (AP) region to inform clinical practice guidelines (CPGs) and to improve osteoporosis care. We present the framework of these clinical standards and describe its development.

    METHODS: We conducted a structured comparative analysis of existing CPGs in the AP region using a "5IQ" model (identification, investigation, information, intervention, integration, and quality). One-hundred data elements were extracted from each guideline. We then employed a four-round Delphi consensus process to structure the framework, identify key components of guidance, and develop clinical care standards.

    RESULTS: Eighteen guidelines were included. The 5IQ analysis demonstrated marked heterogeneity, notably in guidance on risk factors, the use of biochemical markers, self-care information for patients, indications for osteoporosis treatment, use of fracture risk assessment tools, and protocols for monitoring treatment. There was minimal guidance on long-term management plans or on strategies and systems for clinical quality improvement. Twenty-nine APCO members participated in the Delphi process, resulting in consensus on 16 clinical standards, with levels of attainment defined for those on identification and investigation of fragility fractures, vertebral fracture assessment, and inclusion of quality metrics in guidelines.

    CONCLUSION: The 5IQ analysis confirmed previous anecdotal observations of marked heterogeneity of osteoporosis clinical guidelines in the AP region. The Framework provides practical, clear, and feasible recommendations for osteoporosis care and can be adapted for use in other such vastly diverse regions. Implementation of the standards is expected to significantly lessen the global burden of osteoporosis.

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