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Clinicopathological features of bladder tumours in a single institution in Malaysia

Kong CH, Singam P, Hong GE, Cheok LB, Azrif M, Tamil AM, et al.

Asian Pac J Cancer Prev, 2010;11(1):149-52.
PMID: 20593947

OBJECTIVE: To determine the clinicopathological features of bladder tumours encountered over a five year period in Universiti Kebangsaan Malaysia Medical Centre.
METHODS: Medical records of bladder tumour cases from 2005 till 2009 were retrospectively reviewed and tabulated.
RESULTS: A total of 83 cases were recorded. The incidence was highest among the Chinese (56.6%), followed by Malays (34.9%), Indians (6%) and other races (2.4%). The male-to-female ratio was 9.4:1. The median age was 65 years (range 30-91 years) and median duration of follow up was 17.2 months (range 2-60 months). The main histopathology was transitional cell carcinoma (TCC) (90.4%), followed by adenocarcinoma (6%), squamous cell carcinoma (1.2%), leiomyoma (1.2%) and myeloid sarcoma (1.2%). For the TCCs, 58.6% were superficial while 41.4% were muscle invasive, and 13.3% had nodal metastasis with distant metastasis in 8%. Of the total, 5.3% were papillary urothelial tumours of low malignant potential, 33.3% pTa, 20% pT1, 10.7% pT2, 12.0% pT3 and 18.7% pT4. Of the superficial tumours, 32.5% were high grade tumours. There were ten radical cystectomies performed for transitional cell carcinomas; two had neobladder reconstruction whereas the other eight had ileal conduits. All the adenocarcinomas and squamous cell carcinomas were treated by radiotherapy due to the advanced stage of the disease while the myeloid sarcoma received chemotherapy. Mean survival of patients with muscle invasive cancer was 33+/-5 months. By the end of the study, 18.1% of patients had died of their cancer.
CONCLUSION: The incidence of bladder tumours is highest among the Chinese. When compared to other studies, the incidence of muscle invasive and high-grade superficial tumours was greater.
Seven-year review of prostate carcinomas diagnosed by TRUS biopsy in a single Malaysian institution

Hong GE, Kong CH, Singam P, Cheok LB, Zainuddin ZM, Azrif M

Asian Pac J Cancer Prev, 2010;11(5):1351-3.
PMID: 21198291

INTRODUCTION: Analysis of epidemiological as well as survival differences among the multiethnic population of Malaysia with prostate cancer is important.
METHODS: Patients confirmed by transrectal-ultrasonographic-guided-biopsy performed from 2002 to 2008 were enrolled and analysed according to ethnicity, age, PSA level, Gleason score, stage of disease and survival.
RESULTS: Among 83 patients, there were 38 Malay, 40 Chinese, 3 Indians and 2 others. Median age at diagnosis was 69.9 (range: 59-93), 43 patients (51.8%) being diagnosed before the age of 70. The median PSA level upon diagnosis was 574 ng/ml (range: 1-8632) and the median Gleason score was 7 (range: 2-10). Over half were already in Stage 4 when diagnosed. The most common site of metastasis was the bone. As a result the commonest prescribed treatment was hormonal manipulation. Five patients underwent radical prostatectomy and a further thirteen patients had radical radiotherapy (stage I: 1 patient, stage II: 7 patients and stage III: 5 patients). Ten patients defaulted follow-up. The median disease-specific survival was 21.9 months (range: 1-53).
CONCLUSIONS: Prostatic carcinoma is a disease of the elderly and it is frequently diagnosed late in Malaysia. Greater efforts should be made to educate Malaysians regarding prostate cancer.
Reasons, perceived efficacy, and factors associated with complementary and alternative medicine use among Malaysian patients with HIV/AIDS

Hasan SS, See CK, Choong CL, Ahmed SI, Ahmadi K, Anwar M

J Altern Complement Med, 2010 Nov;16(11):1171-6.
PMID: 20973734 DOI: 10.1089/acm.2009.0657

OBJECTIVES: The primary objective of this study was to evaluate the pattern of use, reasons for use, and perceived effect of complementary and alternative medicine (CAM), accompanied by identification and comparison of the factors that are potentially associated with CAM use.
DESIGN: This cross-sectional study was carried out in 325 randomly sampled patients with human immunodeficiency virus/acquired immune deficiency syndrome (HIV/AIDS), at HIV/AIDS referral clinics in the Hospital Sungai Buloh, Malaysia. Simple random sampling was used, where randomization was done using patients' medical record numbers.
SUBJECTS AND METHODS: Semistructured face-to-face interviews were conducted using 38 questions pertaining to type, pattern, perceived efficacy, adverse effects, and influential factors associated with CAM use. In addition, CD4 count and viral load readings were recorded.
RESULTS: Of 325 randomly sampled patients with HIV/AIDS, 254 of them were using some forms of CAM, resulting in a utilization rate of 78.2%. Vitamins and supplements (52.6%), herbal products (33.8%), and massage (16.6%) were the top three most frequently used CAM modalities. Sociodemographic factors including education level (p = 0.021, r(s) = 0.148), monthly income (p = 0.001, r(s) = 0.260), and family history of CAM use (p = 0.001, r(s) = 0.231) were significantly associated and positively correlated with CAM use. However, the majority of these patients (68%) did not disclose CAM use to health care professionals. About half of those who rated their health as good or very good perceived it as a result of CAM use.
CONCLUSIONS: This study confirmed the range of 30%-100% CAM use among individuals infected with HIV/AIDS. Although, on the one hand some types of CAM reduced viral load and enhanced the immune system, on the other hand some forms of CAM produced a detrimental effect on the virological suppression, opening this platform to more research and investigation in order to optimize the use of CAM among patients with HIV/AIDS.
Study site: HIV/AIDS clinic, Hospital Sungai Buloh, Selangor, Malaysia
Fulltext Clinical characteristics of renal cancer in Malaysia : a ten year review

Singam P, Ho C, Hong GE, Mohd A, Tamil AM, Cheok LB, et al.

Asian Pac J Cancer Prev, 2010;11(2):503-6.
PMID: 20843141

Renal cancer is rare and its incidence is 1.9 per 100,000 in the Malaysian population, which consists of three major ethnic groups (Malay, Chinese and Indians). A retrospective study was her conducted to identify clinical characteristics and ethnic background influences on presentation. The study included all renal cancer patients from a single medical institution over ten years, with a total of 75 cases. Seventy-three patients underwent surgery while 2 received only radiotherapy or chemotherapy. The male to female ratio was 2.75:1. Incidence was equal among the Malay (49.3%) and Chinese ethnic groups (45.3%). Mean age of patients were 57.1 (18-93) years old. There were 26 (37.4%) patients with Stage I disease, 14 (18.7%) at Stage II, 23 (30.7%) at Stage III and 12 (16%) at Stage IV. The Chinese race presented at mean older age (p= 0.02) and later stage of disease (p= 0.046). Patients above 40 years old had more advanced stage disease (p= 0.023). Tumour histology were clear cell (72%), urothelial cell (13.3%), sarcomatoid cell and nephroblastoma each contributed 2.7%. The mean tumour size was 8.1 (2-20) cm. There was substantial agreement between the pre and post operative staging (kappa 0.691). In conclusion we observed significant influences of age and race in the clinical presentation of renal cancer in our institution based population. There was larger male to female ratio and mean tumour size as compared to previous epidemiology studies.
Fulltext Spontaneous bladder perforation: a rare complication of tuberculosis

Kong CH, Ali SA, Singam P, Hong GE, Cheok LB, Zainuddin ZM

Int J Infect Dis, 2010 Sep;14 Suppl 3:e250-2.
PMID: 20117032 DOI: 10.1016/j.ijid.2009.10.006

Spontaneous bladder perforation secondary to tuberculosis (TB) is very rare. Only three cases have been reported so far in the literature. Due to its rarity, the diagnosis of spontaneous bladder perforation is often missed. Confirmation of TB via culture takes a long time and starting empirical treatment for TB is necessary. We relate our experience with a young woman who presented with clinical features of a perforated appendix and was only diagnosed with bladder perforation during laparotomy. She also had distal right ureteral stricture and left infundibular stenosis. The provisional diagnosis of TB was attained via typical histopathological features and a positive Mantoux test. She was started empirically on anti-TB treatment and recovered without any complications. Urine culture after 6 weeks confirmed the diagnosis of TB.
Fulltext Encrusted and incarcerated urinary bladder catheter: what are the options?

Ho CC, Khandasamy Y, Singam P, Hong Goh E, Zainuddin ZM

Libyan J Med, 2010 Nov 25;5.
PMID: 21483557 DOI: 10.3402/ljm.v5i0.5686

Urinary bladder catheter encrustations are known complications of long-term urinary catheterisation, which is commonly seen in clinical practice. These encrustations can impede deflation of the balloon and therefore cause problems in the removal of the catheter. The options in managing an encrusted and incarcerated urinary bladder catheter include extracorporeal shock wave lithotripsy and lithoclast. We describe here another technique of dealing with a stuck and encrustated catheter, via direct crushing of the encrustations with a rigid cystoscope inserted through a suprapubic cystostomy tract.
Fulltext Prostate-specific antigen levels among Chinese, Malays and Indians in Singapore from a community-based study

Chia SE, Lau WK, Cheng C, Chin CM, Tan J, Ho SH

Asian Pac J Cancer Prev, 2007 Jul-Sep;8(3):375-8.
PMID: 18159971

The purpose of this study was to examine the distribution of prostate-specific antigen levels among Chinese, Malays and Indians in Singapore, taking the effect of age into consideration. The study was carried out as part of the Singapore Prostate Awareness Week from 23-26th February 2004. Men above 50 years old went to four government-restructured hospitals to participate in the study. Participants filled up a questionnaire and provided 5 ml of blood for measurement of PSA levels using the Abbott IMx Total PSA assay (Abbott Laboratories). 3,486 men responded to the study, comprising 92.8% Chinese, 3.0% Malays, 2.5% Indians and 1.8% Others. 92.7% of them had PSA levels of 4 microg/L or less. There were no significant differences (p<0.05) between the mean PSA levels of Chinese (1.60 microg/L), Malays (1.39 microg/L), Indians (1.23 microg/L) and Others (1.70 microg/L). PSA levels were significantly associated with age (Spearman's r= 0.27, p<0.01). PSA levels increased with each 10-year age group and these trends were significant (p<0.0001) across both PSA group levels and age groupings. In the 50-60 years age groups, the prevalence of PSA levels >4 mug/L were 1.1% and 3.7% respectively. This rose rapidly to 11.3% and 23.5% for age groups >60-70 and >80 years respectively. Our study shows that the median PSA levels in the Caucasian population in the USA are higher than those of Chinese, Malays and Indians in Singapore. PSA levels were positively associated with age. It may be more appropriate to offer PSA testing to men who are >60 years old rather than the current >50 years.
Comparative population structure of Cynopterus fruit bats in peninsular Malaysia and southern Thailand

Campbell P, Schneider CJ, Adnan AM, Zubaid A, Kunz TH

Mol Ecol, 2006 Jan;15(1):29-47.
PMID: 16367828

The extent to which response to environmental change is mediated by species-specific ecology is an important aspect of the population histories of tropical taxa. During the Pleistocene glacial cycles and associated sea level fluctuations, the Sunda region in Southeast Asia experienced concurrent changes in landmass area and the ratio of forest to open habitat, providing an ideal setting to test the expectation that habitat associations played an important role in determining species' response to the opportunity for geographic expansion. We used mitochondrial control region sequences and six microsatellite loci to compare the phylogeographic structure and demographic histories of four broadly sympatric species of Old World fruit bats in the genus, Cynopterus. Two forest-associated species and two open-habitat generalists were sampled along a latitudinal transect in Singapore, peninsular Malaysia, and southern Thailand. Contrary to expectations based on habitat associations, the geographic scale of population structure was not concordant across ecologically similar species. We found evidence for long and relatively stable demographic history in one forest and one open-habitat species, and inferred non-coincident demographic expansions in the second forest and open-habitat species. Thus, while these results indicate that Pleistocene climate change did not have a single effect on population structure across species, a correlation between habitat association and response to environmental change was supported in only two of four species. We conclude that interactions between multiple factors, including historical and contemporary environmental change, species-specific ecology and interspecific interactions, have shaped the recent evolutionary histories of Cynopterus fruit bats in Southeast Asia.
Phylogeny and phylogeography of Old World fruit bats in the Cynopterus brachyotis complex

Campbell P, Schneider CJ, Adnan AM, Zubaid A, Kunz TH

Mol Phylogenet Evol, 2004 Dec;33(3):764-81.
PMID: 15522802

Taxonomic relationships within the Old World fruit bat genus, Cynopterus, have been equivocal for the better part of a century. While nomenclature has been revised multiple times on the basis of phenotypic characters, evolutionary relationships among taxa representing the entire geographic range of the genus have not been determined. We used mitochondrial DNA sequence data to infer phylogenetic relationships among the three most broadly distributed members of the genus: C. brachyotis, C. horsfieldi, and C. sphinx, and to assess whether C. brachyotis represents a single widespread species, or a complex of distinct lineages. Results clearly indicate that C. brachyotis is a complex of lineages. C. sphinx and C. horsfieldi haplotypes formed monophyletic groups nested within the C. brachyotis species complex. We identified six divergent mitochondrial lineages that are currently referred to C. brachyotis. Lineages from India, Myanmar, Sulawesi, and the Philippines are geographically well-defined, while in Malaysia two lineages, designated Sunda and Forest, are broadly sympatric and may be ecologically distinct. Demographic analyses of the Sunda and Forest lineages suggest strikingly different population histories, including a recent and rapid range expansion in the Sunda lineage, possibly associated with changes in sea levels during the Pleistocene. The resolution of the taxonomic issues raised in this study awaits combined analysis of morphometric characters and molecular data. However, since both the Indian and Malaysian Forest C. brachyotis lineages are apparently ecologically restricted to increasingly fragmented forest habitat, we suggest that reevaluation of the conservation status of populations in these regions should be an immediate goal.
Ethnic variability in dementia: results from Singapore

Ampil ER, Fook-Chong S, Sodagar SN, Chen CP, Auchus AP

Alzheimer Dis Assoc Disord, 2005 Oct-Dec;19(4):184-5.
PMID: 16327344

The diversity of Singapore's population affords a unique opportunity to study ethnic variability in the dementias. We sought to explore the effects of ethnicity on the frequency of Alzheimer disease and vascular dementia in a large Singaporean sample. A total of 357 patients were studied: 190 with vascular dementia and 167 with Alzheimer disease. Vascular dementia was more common among Chinese and Malays, whereas Alzheimer disease was more common in Indians and Eurasians. Factors that may contribute to the observed ethnic variability in dementia etiologies include differential frequency of the ApoE-e4 allele, frequency of vascular risk factors, lifestyle choices, and cultural attitudes toward health care utilization.
Asthma control in adults in Asia-Pacific

Zainudin BM, Lai CK, Soriano JB, Jia-Horng W, De Guia TS, Asthma Insights and Reality in Asia-Pacific (AIRIAP) Steering Committee

Respirology, 2005 Nov;10(5):579-86.
PMID: 16268910 DOI: 10.1111/j.1440-1843.2005.00753.x

OBJECTIVE: The Asthma Insights and Reality in Asia-Pacific (AIRIAP) survey collected detailed information on asthma severity and management in the urban centres of eight areas of the Asia-Pacific region. This study compared asthma morbidity and management practices in these areas.
METHODOLOGY: Following recruitment, face-to-face interviews were completed with 2323 adults with diagnosed asthma, who had current symptoms or were using asthma medication. Comparisons between areas were made for asthma severity, asthma burden and management practices.
RESULTS Asthma severity varied significantly between areas (P < 0.01), with Vietnam and mainland China reporting the most cases with severe, persistent symptoms. Severity of asthma was significantly associated with advancing age and a lower level of education in a multivariate analysis (P < 0.001). The total use of acute healthcare for asthma was significantly associated with increased asthma severity. Work absence due to asthma was highest in the Philippines (46.6%) and lowest in South Korea (7.5%). The use of inhaled corticosteroids was associated with age in a non-linear manner. There was significant variation among countries in usage of inhaled corticosteroids, from 1.3% in South Korea to 29.0% in Taiwan (P < 0.00001). A peak flow meter was owned by a total of 7.7% of respondents, and overall, 17.9% of adults had a written action plan for asthma management.
CONCLUSIONS: Within the Asia-Pacific region, asthma in adults differs significantly in disease severity, management and treatment according to area of residence. International recommendations on the management of asthma are generally not being followed.
Study site: urban areas in several countries in Asia-Pacific region (via random street interception, random door-to-door recruitment, or telephone recruitment)
Fulltext Whole Genome Sequencing of the Asian Arowana (Scleropages formosus) Provides Insights into the Evolution of Ray-Finned Fishes

Austin CM, Tan MH, Croft LJ, Hammer MP, Gan HM

Genome Biol Evol, 2015 Oct;7(10):2885-95.
PMID: 26446539 DOI: 10.1093/gbe/evv186

The Asian arowana (Scleropages formosus) is of commercial importance, conservation concern, and is a representative of one of the oldest lineages of ray-finned fish, the Osteoglossomorpha. To add to genomic knowledge of this species and the evolution of teleosts, the genome of a Malaysian specimen of arowana was sequenced. A draft genome is presented consisting of 42,110 scaffolds with a total size of 708 Mb (2.85% gaps) representing 93.95% of core eukaryotic genes. Using a k-mer-based method, a genome size of 900 Mb was also estimated. We present an update on the phylogenomics of fishes based on a total of 27 species (23 fish species and 4 tetrapods) using 177 orthologous proteins (71,360 amino acid sites), which supports established relationships except that arowana is placed as the sister lineage to all teleost clades (Bayesian posterior probability 1.00, bootstrap replicate 93%), that evolved after the teleost genome duplication event rather than the eels (Elopomorpha). Evolutionary rates are highly heterogeneous across the tree with fishes represented by both slowly and rapidly evolving lineages. A total of 94 putative pigment genes were identified, providing the impetus for development of molecular markers associated with the spectacular colored phenotypes found within this species.
A negative waveform in the scotopic response in a patient with phosphoglycerate kinase deficiency: a visual electrophysiology report

Mohd Khialdin S, Grigg J, Rowe N, Crofts S, Wilson M, Troedson C

Documenta ophthalmologica. Advances in ophthalmology, 2015 Dec;131(3):215-20.
PMID: 26396085 DOI: 10.1007/s10633-015-9511-0

Phosphoglycerate kinase (PGK) deficiency is an X-linked neurometabolic genetic disorder with variable systemic manifestations. So far, only one patient with retinal anomalies has been reported, but no visual electrophysiology findings were described. We report the first description of visual electrophysiology in a child with PGK deficiency. This provides further information for the site of involvement in the eye.
Fulltext Positron Emission Tomographic Imaging in Stroke: Cross-Sectional and Follow-Up Assessment of Amyloid in Ischemic Stroke

Sahathevan R, Linden T, Villemagne VL, Churilov L, Ly JV, Rowe C, et al.

Stroke, 2016 Jan;47(1):113-9.
PMID: 26578658 DOI: 10.1161/STROKEAHA.115.010528

Cardiovascular risk factors significantly increase the risk of developing Alzheimer disease. A possible mechanism may be via ischemic infarction-driving amyloid deposition. We conducted a study to determine the presence of β-amyloid in infarct, peri-infarct, and hemispheric areas after stroke. We hypothesized that an infarct would trigger β-amyloid deposition, with deposition over time.
Depression, anxiety and stress among patients with dialysis and the association with quality of life

Bujang MA, Musa R, Liu WJ, Chew TF, Lim CT, Morad Z

Asian J Psychiatr, 2015 Dec;18:49-52.
PMID: 26549864 DOI: 10.1016/j.ajp.2015.10.004

Studies addressing the nature of relationship between psychological symptoms and quality of life among dialysis patients in Malaysia are scarce. Hence, this study is intended to investigate the association between psychological symptoms such as depression, anxiety and stress on the quality of life in dialysis patients. A cross sectional multicentre study was conducted from May to October 2012 at 15 centres that provide haemodialysis and/or peritoneal dialysis. Apart from socio-demographic profile data collection, WHOQOL-BREF and DASS21 questionnaires were administered to study subjects. All three psychological symptoms had significant impact on quality of life domains of physical health, psychological health, social impact, perceived environment and overall quality of life. These findings suggest that subjects with symptoms of depression, anxiety and stress had poorer quality of life than those without, highlighting the negative impact of psychological symptoms.
Fulltext Genome sequencing and annotation of Cellulomonas sp. HZM

Chua P, Har ZM, Austin CM, Yule CM, Dykes GA, Lee SM

Genom Data, 2015 Sep;5:40-1.
PMID: 26484221 DOI: 10.1016/j.gdata.2015.05.009

We report the draft genome sequence of Cellulomonas sp. HZM, isolated from a tropical peat swamp forest. The draft genome size is 3,559,280 bp with a G + C content of 73% and contains 3 rRNA sequences (single copies of 5S, 16S and 23S rRNA).
Fulltext Genome sequencing and annotation of Aeromonas sp. HZM

Chua P, Har ZM, Austin CM, Yule CM, Dykes GA, Lee SM

Genom Data, 2015 Sep;5:38-9.
PMID: 26484220 DOI: 10.1016/j.gdata.2015.05.008

We report the draft genome sequence of Aeromonas sp. strain HZM, isolated from tropical peat swamp forest soil. The draft genome size is 4,451,364 bp with a G + C content of 61.7% and contains 10 rRNA sequences (eight copies of 5S rRNA genes, single copy of 16S and 23S rRNA each). The genome sequence can be accessed at DDBJ/EMBL/GenBank under the accession no. JEMQ00000000.
Assessment of the migration potential of nanosilver from nanoparticle-coated low-density polyethylene food packaging into food simulants

Hannon JC, Kerry JP, Cruz-Romero M, Azlin-Hasim S, Morris M, Cummins E

Food Addit Contam Part A Chem Anal Control Expo Risk Assess, 2016;33(1):167-78.
PMID: 26523861 DOI: 10.1080/19440049.2015.1114184

An experimental nanosilver-coated low-density polyethylene (LDPE) food packaging was incubated with food simulants using a conventional oven and tested for migration according to European Commission Regulation No. 10/2011. The commercial LDPE films were coated using a layer-by-layer (LbL) technique and three levels of silver (Ag) precursor concentration (0.5%, 2% and 5% silver nitrate (AgNO3), respectively) were used to attach antimicrobial Ag. The experimental migration study conditions (time, temperature and food simulant) under conventional oven heating (10 days at 60°C, 2 h at 70°C, 2 h at 60°C or 10 days at 70°C) were chosen to simulate the worst-case storage period of over 6 months. In addition, migration was quantified under microwave heating. The total Ag migrant levels in the food simulants were quantified by inductively coupled plasma-atomic emission spectroscopy (ICP-AES). Mean migration levels obtained by ICP-AES for oven heating were in the range 0.01-1.75 mg l(-1). Migration observed for microwave heating was found to be significantly higher when compared with oven heating for similar temperatures (100°C) and identical exposure times (2 min). In each of the packaging materials and food simulants tested, the presence of nanoparticles (NPs) was confirmed by scanning electron microscopy (SEM). On inspection of the migration observed under conventional oven heating, an important finding was the significant reduction in migration resulting from the increased Ag precursor concentration used to attach Ag on the LDPE LbL-coated films. This observation merits further investigation into the LbL coating process used, as it suggests potential for process modifications to reduce migration. In turn, any reduction in NP migration below regulatory limits could greatly support the antimicrobial silver nanoparticle (AgNP)-LDPE LbL-coated films being used as a food packaging material.
Psychological processes of suffering of palliative care patients in Malaysia: a thematic analysis

Tan SB, Loh EC, Lam CL, Ng CG, Lim EJ, Boey CCM

BMJ Support Palliat Care, 2019 Mar;9(1):e19.
PMID: 27098972 DOI: 10.1136/bmjspcare-2015-001064

Although suffering in palliative care has received increasing attention over the past decade, the psychological processes that underpin suffering remain relatively unexplored.
OBJECTIVE: To understand the psychological processes involved in the experiencing of suffering at the end phase of life.
METHODS: Semistructured interviews were conducted with 20 palliative care inpatients from an academic medical centre in Kuala Lumpur, Malaysia. The transcripts were thematically analysed with NVIVO9.
RESULTS: 5 themes of psychological processes of suffering were generated: (1) perceptions, (2) cognitive appraisals, (3) hope and the struggles with acceptance, (4) emotions and (5) clinging. A model of suffering formation was constructed.
CONCLUSION: The findings may inform the development of mechanism-based interventions in the palliation of suffering.
The role of infarct transmural extent in infarct extension: A computational study

Leong CN, Lim E, Andriyana A, Al Abed A, Lovell NH, Hayward C, et al.

Int J Numer Method Biomed Eng, 2017 Feb;33(2).
PMID: 27043925 DOI: 10.1002/cnm.2794

Infarct extension, a process involving progressive extension of the infarct zone (IZ) into the normally perfused border zone (BZ), leads to continuous degradation of the myocardial function and adverse remodelling. Despite carrying a high risk of mortality, detailed understanding of the mechanisms leading to BZ hypoxia and infarct extension remains unexplored. In the present study, we developed a 3D truncated ellipsoidal left ventricular model incorporating realistic electromechanical properties and fibre orientation to examine the mechanical interaction among the remote, infarct and BZs in the presence of varying infarct transmural extent (TME). Localized highly abnormal systolic fibre stress was observed at the BZ, owing to the simultaneous presence of moderately increased stiffness and fibre strain at this region, caused by the mechanical tethering effect imposed by the overstretched IZ. Our simulations also demonstrated the greatest tethering effect and stress in BZ regions with fibre direction tangential to the BZ-remote zone boundary. This can be explained by the lower stiffness in the cross-fibre direction, which gave rise to a greater stretching of the IZ in this direction. The average fibre strain of the IZ, as well as the maximum stress in the sub-endocardial layer, increased steeply from 10% to 50% infarct TME, and slower thereafter. Based on our stress-strain loop analysis, we found impairment in the myocardial energy efficiency and elevated energy expenditure with increasing infarct TME, which we believe to place the BZ at further risk of hypoxia. Copyright © 2016 John Wiley & Sons, Ltd.

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