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Fulltext Molecular Dynamics Study of Poly(dimethylsiloxane) Nanostructure Distortion in a Soft Lithography Demolding Process

Abdul Manap AH, Md Izah SS, Mohamed K

ACS Omega, 2019 Dec 03;4(23):20257-20264.
PMID: 31815228 DOI: 10.1021/acsomega.9b02547

This study aims at investigating the distortion of poly(dimethylsiloxane) (PDMS) nanostructures in a soft lithography demolding process using molecular dynamics simulation. Experimental results show that after peeling, PDMS nanopillars became 10-60% longer in height than the mold size. Molecular dynamics simulations have been employed to plot the stress-strain curve of the nanopillars when subjected to uniaxial stress. Three force fields (COMPASS, CVFF, and PCFF) were used for modeling. The demolding process in soft lithography and nanoimprint lithography causes significant deformation in replication. The experimental results show clear signs of elongation after demolding. Molecular dynamics simulations are employed to study the stress-strain relationship of the PDMS nanopillars. The results from the simulation show that a PDMS nanopillar at temperature T = 300 K under tensile stress shows characteristics of flexible plastic under tensile stress and has a lower Young's modulus, ultimate tensile stress, and Poisson's ratio.
Fulltext Application of medical information system to identify dengue outbreak factors: Insights from a hyperendemic city in Malaysia

Keat-Chuan Ng C, Linus-Lojikip S, Mohamed K, Hss AS

Int J Med Inform, 2023 Sep;177:105162.
PMID: 37549500 DOI: 10.1016/j.ijmedinf.2023.105162

BACKGROUND: Dengue is widespread globally, but it is more severe in hyperendemic regions where the virus, its vectors, and its human hosts naturally occur. The problem is particularly acute in cities, where outbreaks affect a large human population living in a wide array of socio-environmental conditions. Controlling outbreaks will rely largely on systematic data collection and analysis approaches to uncover nuances on a city-by-city basis due to the diversity of factors.
OBJECTIVE: The main objective of this study is to consolidate and analyse the dengue case dataset amassed by the e-Dengue web-based information system, developed by the Ministry of Health Malaysia, to improve our epidemiological understanding.
METHODS: We retrieved data from the e-Dengue system and integrated a total of 18,812 cases from 2012 to 2019 (8 years) with meteorological data, geoinformatics techniques, and socio-environmental observations to identify plausible factors that could have caused dengue outbreaks in Ipoh, a hyperendemic city in Malaysia.
RESULTS: The rainfall trend characterised by a linearity of R2 > 0.99, termed the "wet-dry steps", may be the unifying factor for triggering dengue outbreaks, though it is still a hypothesis that needs further validation. Successful mapping of the dengue "reservoir" contact zones and spill-over diffusion revealed socio-environmental factors that may be controlled through preventive measures. Age is another factor to consider, as the platelet and white blood cell counts in the "below 5" age group are much greater than in other age groups.
CONCLUSIONS: Our work demonstrates the novelty of the e-Dengue system, which can identify outbreak factors at high resolution when integrated with non-medical fields. Besides dengue, the techniques and insights laid out in this paper are valuable, at large, for advancing control strategies for other mosquito-borne diseases such as malaria, chikungunya, and zika in other hyperendemic cities elsewhere globally.
Myxozoan infection of the Malaysian mahseer, Tor tambroides, of Tasik Kenyir Reservoir, Malaysia: description of a new species Myxobolus tambroides sp.n

Székely C, Shaharom F, Cech G, Mohamed K, Zin NA, Borkhanuddin MH, et al.

Parasitol Res, 2012 Oct;111(4):1749-56.
PMID: 22782473

Tor tambroides, a common and appreciated cyprinid fish of the Tasik Kenyir water reservoir in Malaysia, is one of the species selected for propagation. This fish was first successfully propagated in Malaysia by the Department of Agriculture, Sarawak, Malaysia, and the breeding program continued throughout the country. The gills were frequently infected by a Myxobolus species to be described as Myxobolus tambroides sp. n. The small, 50 to 70 μm, round plasmodia of this species is located intralamellarly. Plasmodia were filled with pyriform myxospores, 9.9 and 7.4 μm wide. In sutural view, the caudal end of the myxospores had a distinctive valvular groove, parallel with the suture. Plasmodia caused deformations on the affected and the neighbouring gill lamellae. The 18S rDNA sequence of M. tambroides sp.n. did not show a close relationship with any other Myxobolus spp., represented in the GenBank. This might be an emerging parasite likely to impact the propagation of this fish.
Fulltext NiO nanoparticles induce cytotoxicity mediated through ROS generation and impairing the antioxidant defense in the human lung epithelial cells (A549): Preventive effect of Pistacia lentiscus essential oil

Mohamed K, Zine K, Fahima K, Abdelfattah E, Sharifudin SM, Duduku K

Toxicol Rep, 2018;5:480-488.
PMID: 29854619 DOI: 10.1016/j.toxrep.2018.03.012

Nickel oxide nanoparticles (NiO NPs) have attracted increasing attention owing to potential capacity to penetrate to several human cell systems and exert a toxic effect. Elsewhere, the use of medicinal plants today is the form of the most widespread medicine worldwide. Utilizing aromatic plants as interesting source of phytochemicals constitute one of the largest scientific concerns. Thus this study was focused to investigate antioxidant and cytoprotective effects of essential oil of a Mediterranean plant P. lentiscus (PLEO) on NiO NPs induced cytotoxicity and oxidative stress in human lung epithelial cells (A549). The obtained results showed that cell viability was reduced by NiO NPs, who's also found to induce oxidative stress in dose-dependent manner indicated by induction of reactive oxygen species and reduction of antioxidant enzymes activities. Our results also demonstrated that PLEO contains high amounts in terpinen-4-ol (11.49%), germacrene D (8.64%), α-pinene (5.97%), sabinene (5.19%), caryophyllene (5.10%) and δ-Cadinene (4.86%). PLEO exhibited a potent antioxidant capacity by cell viability improving, ROS scavenging and enhancing the endogenous antioxidant system against NiO NPs in this model of cells. The present work demonstrated, for the first time, the protective activity of PLEO against cell oxidative damage induced by NiO NPs. It was suggested that this plant essential oil could be use as a cells protector.
Fulltext Comparative validity of a Food Frequency Questionnaire (MyUM Adolescent FFQ) to estimate the habitual dietary intake of adolescents in Malaysia

Mohamed K, Tin TS, Jalaludin MY, Al-Sadat N, Majid HA

Asia Pac J Clin Nutr, 2018 7 27;27(4):898-907.
PMID: 30045437 DOI: 10.6133/apjcn.022018.03

BACKGROUND AND OBJECTIVES: The food frequency questionnaire (FFQ) is a dietary tool used to assess the habitual intake of the population. The goal of this study is to examine the reproducibility and validity of the FFQ that was developed for a multi-ethnic population in Malaysia.
METHODS AND STUDY DESIGN: Collective food data from MyHeARTs 2012 database were used to construct the MyUM Adolescent FFQ. Seventy-eight participants between 13 and 15 years old in 2014 were selected through convenient sampling for test-retest study. They completed the MyUM Adolescent FFQ twice, with an interval period of one week. One hundred and fifty-six MyHeARTs study participants who were 15 years old in 2014 were randomly selected for this comparative valid-ity study. They completed a 7-day diet history (7DDH) and subsequently completed the self-administered MyUM Adolescent FFQ.
RESULTS: Pearson's correlations between the FFQ and 7DDH for all macronutrients were statistically significant. Energy-adjusted correlations for protein, carbohydrate, and fat were 0.54, 0.63 and 0.49 respectively. Most of the micronutrients and minerals, were statistically correlated ranging from 0.31 to 0.49 after energy adjustment. Cross-classification analyses revealed that more than 70 percent of adolescents were classified into either the same or adjacent quartile of nutrient intake when comparing data of 7DDH and FFQ. No serious systematic bias was evident in the Bland-Altman plots.
CONCLUSION: The 200-item FFQ developed for Malaysian adolescents has moderate to good comparative validity for assessment of macronutrient and micronutrient intake.
Fulltext Prevalence of obesity and metabolic derangement among the rural population of Kiulu district of Sabah, Malaysia: a health screening programme findings

Zarkasi KA, Ramli NZ, Mohamed K, Palasuberniam P, D’ Souza UJA

Borneo Journal of Medical Sciences, 2018;12(2):1-7.
MyJurnal

Malaysia has high prevalence of general and central obesity which can be signified by measurements of BMI and waist circumference respectively. Both parameters are established risk factors and predictors for non-communicable diseases including diabetes and hypertension. A health screening programme was conducted in a rural district of Sabah, Malaysia where a total of 42 participants were examined for weight, height, BMI, waist circumference, systolic and diastolic blood pressure, pulse rate and capillary blood glucose. Mean age of the participants was 52.4 ± 14.9 years old. General obesity based on BMI was 42.9% while central obesity based on waist circumference was 26.2%. Proportion for hypertension and hyperglycaemia were equal at 33.3%. BMI was strongly correlated to waist circumference (r = 0.873, p < 0.001). Moreover, both BMI and waist circumference were independently correlated with systolic blood pressure (r = 0.418, p = 0.006 and r = 0.383, p = 0.012 respectively). Finally, systolic blood pressure was directly correlated with weight of the participants (r = 0.350, p = 0.023). These findings were found to be closely similar and comparable to currently available epidemiological data.
The prevalence of gestational diabetes, associated factors and feto-maternal outcome among antenatal women attending health clinics in Terengganu

Abd Latif R, Yusof NA, Yahya R, Muda Z, Tengku Lih TB, Mohamed K, et al.

Malays Fam Physician, 2022 Nov 30;17(3):43-52.
PMID: 36606162 DOI: 10.51866/oal302

INTRODUCTION: Gestational diabetes mellitus (GDM) is a known risk factor for diabetes mellitus (DM). The rising prevalence of GDM in the Asian population (11.7%) may explain the increasing incidence of DM in women. This study examined the prevalence of GDM, its associated factors and the foeto-maternal outcomes of women with GDM in Terengganu.
METHOD: A cross-sectional study was conducted between April and September 2019 using secondary data from antenatal records in 40 health clinics in Terengganu for 2018. All pregnant women aged 25 years and above with or without risk factors for GDM were included in the study. Those with pre-existing type 1 or 2 DM were excluded. A total of 270 respondents were included. The prevalence of GDM and its associated factors were determined using descriptive statistics followed by multiple logistic regression.
RESULTS: The prevalence of GDM in Terengganu was 27.3% (n=72). Logistic regression analysis found that BMI at booking (adjusted OR=4.51, 95% CI 2.13-9.55, p<0.001), history of GDM (adjusted OR=5.31, 95% CI 2.17-12.99, p<0.001) and family history of DM (adjusted OR=4.24, 95% CI 2.23-8.05, p<0.001) were the significant associated risk factors. Of women with GDM, 17.7% (n=11) had postpartum pre-diabetes based on modified oral glucose tolerance at 6 weeks postpartum. Univariate analysis using chi-square tests showed a significant association of neonatal jaundice and hypoglycaemia with GDM.
CONCLUSION: Because the prevalence of GDM in Terengganu is high, surveillance of GDM in highrisk pregnancies and effective glycaemic management should be emphasised to prevent adverse foeto-maternal outcomes.
Fulltext Borderless collaboration is needed for COVID-19-A disease that knows no borders

Mohamed K, Rodríguez-Román E, Rahmani F, Zhang H, Ivanovska M, Makka SA, et al.

Infect Control Hosp Epidemiol, 2020 Oct;41(10):1245-1246.
PMID: 32319878 DOI: 10.1017/ice.2020.162
COVID-19 vaccinations: The unknowns, challenges, and hopes

Mohamed K, Rzymski P, Islam MS, Makuku R, Mushtaq A, Khan A, et al.

J Med Virol, 2022 Apr;94(4):1336-1349.
PMID: 34845731 DOI: 10.1002/jmv.27487

The entire world has been suffering from the coronavirus disease 2019 (COVID-19) pandemic since March 11, 2020. More than a year later, the COVID-19 vaccination brought hope to control this viral pandemic. Here, we review the unknowns of the COVID-19 vaccination, such as its longevity, asymptomatic spread, long-term side effects, and its efficacy on immunocompromised patients. In addition, we discuss challenges associated with the COVID-19 vaccination, such as the global access and distribution of vaccine doses, adherence to hygiene guidelines after vaccination, the emergence of novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants, and vaccine resistance. Despite all these challenges and the fact that the end of the COVID-19 pandemic is still unclear, vaccines have brought great hope for the world, with several reports indicating a significant decline in the risk of COVID19-related infection and hospitalizations.
Fulltext GestaltMatcher Database - A global reference for facial phenotypic variability in rare human diseases

Lesmann H, Hustinx A, Moosa S, Klinkhammer H, Marchi E, Caro P, et al.

Res Sq, 2024 Jun 10.
PMID: 38903062 DOI: 10.21203/rs.3.rs-4438861/v1

The most important factor that complicates the work of dysmorphologists is the significant phenotypic variability of the human face. Next-Generation Phenotyping (NGP) tools that assist clinicians with recognizing characteristic syndromic patterns are particularly challenged when confronted with patients from populations different from their training data. To that end, we systematically analyzed the impact of genetic ancestry on facial dysmorphism. For that purpose, we established the GestaltMatcher Database (GMDB) as a reference dataset for medical images of patients with rare genetic disorders from around the world. We collected 10,980 frontal facial images - more than a quarter previously unpublished - from 8,346 patients, representing 581 rare disorders. Although the predominant ancestry is still European (67%), data from underrepresented populations have been increased considerably via global collaborations (19% Asian and 7% African). This includes previously unpublished reports for more than 40% of the African patients. The NGP analysis on this diverse dataset revealed characteristic performance differences depending on the composition of training and test sets corresponding to genetic relatedness. For clinical use of NGP, incorporating non-European patients resulted in a profound enhancement of GestaltMatcher performance. The top-5 accuracy rate increased by +11.29%. Importantly, this improvement in delineating the correct disorder from a facial portrait was achieved without decreasing the performance on European patients. By design, GMDB complies with the FAIR principles by rendering the curated medical data findable, accessible, interoperable, and reusable. This means GMDB can also serve as data for training and benchmarking. In summary, our study on facial dysmorphism on a global sample revealed a considerable cross ancestral phenotypic variability confounding NGP that should be counteracted by international efforts for increasing data diversity. GMDB will serve as a vital reference database for clinicians and a transparent training set for advancing NGP technology.
Fulltext GestaltMatcher Database - A global reference for facial phenotypic variability in rare human diseases

Lesmann H, Hustinx A, Moosa S, Klinkhammer H, Marchi E, Caro P, et al.

medRxiv, 2024 May 21.
PMID: 37503210 DOI: 10.1101/2023.06.06.23290887

The most important factor that complicates the work of dysmorphologists is the significant phenotypic variability of the human face. Next-Generation Phenotyping (NGP) tools that assist clinicians with recognizing characteristic syndromic patterns are particularly challenged when confronted with patients from populations different from their training data. To that end, we systematically analyzed the impact of genetic ancestry on facial dysmorphism. For that purpose, we established the GestaltMatcher Database (GMDB) as a reference dataset for medical images of patients with rare genetic disorders from around the world. We collected 10,980 frontal facial images - more than a quarter previously unpublished - from 8,346 patients, representing 581 rare disorders. Although the predominant ancestry is still European (67%), data from underrepresented populations have been increased considerably via global collaborations (19% Asian and 7% African). This includes previously unpublished reports for more than 40% of the African patients. The NGP analysis on this diverse dataset revealed characteristic performance differences depending on the composition of training and test sets corresponding to genetic relatedness. For clinical use of NGP, incorporating non-European patients resulted in a profound enhancement of GestaltMatcher performance. The top-5 accuracy rate increased by +11.29%. Importantly, this improvement in delineating the correct disorder from a facial portrait was achieved without decreasing the performance on European patients. By design, GMDB complies with the FAIR principles by rendering the curated medical data findable, accessible, interoperable, and reusable. This means GMDB can also serve as data for training and benchmarking. In summary, our study on facial dysmorphism on a global sample revealed a considerable cross ancestral phenotypic variability confounding NGP that should be counteracted by international efforts for increasing data diversity. GMDB will serve as a vital reference database for clinicians and a transparent training set for advancing NGP technology.

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