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A low-cost, high-quality method for remote recording of presentations

Tan LK, Wong JH, Ng KH

AJR Am J Roentgenol, 2006 Mar;186(3):898-901.
PMID: 16498128

The purpose of this article was to develop a low-cost method for high-quality remote capturing and recording of multimedia presentations.
Fulltext Case Series of Osmotic Demyelination Syndrome Treated With Plasmapheresis: Experience From Two Tertiary Hospitals

Lim KY, Chia YK, Khoo CS, Tan HJ

J Clin Neurol, 2022 Jan;18(1):117-119.
PMID: 35021290 DOI: 10.3988/jcn.2022.18.1.117
Fulltext Uncovering drug repurposing candidates for head and neck cancers: insights from systematic pharmacogenomics data analysis

Chai AWY, Tan AC, Cheong SC

Sci Rep, 2021 12 14;11(1):23933.
PMID: 34907286 DOI: 10.1038/s41598-021-03418-1

Effective treatment options for head and neck squamous cell carcinoma (HNSCC) are currently lacking. We exploited the drug response and genomic data of the 28 HNSCC cell lines, screened with 4,518 compounds, from the PRISM repurposing dataset to uncover repurposing drug candidates for HNSCC. A total of 886 active compounds, comprising of 418 targeted cancer, 404 non-oncology, and 64 chemotherapy compounds were identified for HNSCC. Top classes of mechanism of action amongst targeted cancer compounds included PI3K/AKT/MTOR, EGFR, and HDAC inhibitors. We have shortlisted 36 compounds with enriched killing activities for repurposing in HNSCC. The integrative analysis confirmed that the average expression of EGFR ligands (AREG, EREG, HBEGF, TGFA, and EPGN) is associated with osimertinib sensitivity. Novel putative biomarkers of response including those involved in immune signalling and cell cycle were found to be associated with sensitivity and resistance to MEK inhibitors respectively. We have also developed an RShiny webpage facilitating interactive visualization to fuel further hypothesis generation for drug repurposing in HNSCC. Our study provides a rich reference database of HNSCC drug sensitivity profiles, affording an opportunity to explore potential biomarkers of response in prioritized drug candidates. Our approach could also reveal insights for drug repurposing in other cancers.
Fulltext Single nucleotide polymorphism in the promoter of the human interleukin-13 gene is associated with asthma in Malaysian adults

Radhakrishnan AK, Raj VL, Tan LK, Liam CK

Biomed Res Int, 2013;2013:981012.
PMID: 23865080 DOI: 10.1155/2013/981012

Asthma susceptibility genes are mapped to a region on human chromosome 5q31-q33, which contains a cluster of proinflammatory cytokine genes such as interleukin-13 (IL-13), which is associated with asthma. This study investigated the allele frequencies of two single nucleotide polymorphisms (SNPs) (-1111C>T and 4257C>A) in the IL-13 gene between asthmatics and healthy volunteers as well as the relationship between these SNPs and IL-13 production. DNA extracted from buffy coat of asthmatic and control subjects was genotyped using the PCR-RFLP method. Amount of IL-13 produced by mitogen-stimulated peripheral blood leucocytes PBLs (PBLs) was determined by ELISA. The frequencies of the -1111C and 4257G wild-type alleles were 0.52 and 0.55 in asthmatics and were 0.67 and 0.56 in controls. A significant (P < 0.05) association was found between genotype and allele frequencies of SNP at position -1111C>T between asthmatic and control groups (OR, 1.810; 95% CI = 1.184 to 2.767; P < 0.05). The mitogen-stimulated PBLs from asthmatics produced higher amounts of IL-13 production (P < 0.001). The 4257GA heterozygous and 4257AA homozygous mutant alleles were associated with higher IL-13 production in asthmatics (P < 0.05). Our results show that the -1111T mutant allele are associated with asthma and the 4257A mutant alleles are associated with elevated IL-13 production.
Gas chromatographic method validation for the analysis of major components in illicit heroin seized in Malaysia

Chan KW, Tan GH, Wong RC

Sci Justice, 2012 Mar;52(1):9-16.
PMID: 22325905 DOI: 10.1016/j.scijus.2011.07.005

Apart from routine analysis of total morphine content required by the criminal justice system, quantification of other major components in illicit heroin has not been considered by the Malaysian enforcement laboratory. In order to quantify various other cutting agents in addition to alkaloids, a gas chromatographic (GC) method was developed to facilitate simultaneous quantification of eight target analytes commonly found in illicit heroin seized in Malaysia within a 12 min run time. The validation results demonstrated high selectivity with the use of an HP Ultra 2 capillary column. Different solvents were studied and methanol:chloroform (1:9) proved best for sample dissolution. The method was repeatable and reproducible. The study ranges covering 50-150% of the preferred concentrations of the eight analytes obtained r(2)>0.9997. Limits of detection up to 6μg/mL were also obtained and the method achieved 99-102% recovery. The capability of the method in heroin profiling was verified using samples from ten case samples.
Investigation of trace inorganic elements in street doses of heroin

Chan KW, Tan GH, Wong RC

Sci Justice, 2013 Mar;53(1):73-80.
PMID: 23380066 DOI: 10.1016/j.scijus.2012.08.004

Sixteen trace elements found in 309 street heroin samples, piped water and contaminated water were determined using inductively coupled plasma-mass spectrometry. All the street heroin samples were found to contain high levels of sodium, a reflection of the use of sodium bicarbonate during heroin synthesis. Additionally, this element was also found to be one of the potential contaminants acquired from the piped water. Calcium could be derived from lime while iron, aluminum and zinc could have come from the metallic container used in the processing/cutting stage. The levels of these elements remained low in the heroin and it could be due to the dilution effects from the addition of adulterants. Statistical validation was performed with six links of related heroin samples using principal component analysis to find the best pretreatment for sample classification. It was obtained that normalization followed by fourth root showed promising results with 8% errors in the sample clustering. The technique was then applied to the case samples. Finally, the result suggested that the case samples could have originated from at least two major groups respectively showing unique elemental profiles at the street level.
A simplified clustering method for novice narcotic chemists

Chan KW, Tan GH, Wong RC

Sci Justice, 2012 Sep;52(3):136-41.
PMID: 22841136 DOI: 10.1016/j.scijus.2012.04.006

Statistical classification remains the most useful statistical tool for forensic chemists to assess the relationships between samples. Many clustering techniques such as principal component analysis and hierarchical cluster analysis have been employed to analyze chemical data for pattern recognition. Due to the feeble foundation of this statistics knowledge among novice drug chemists, a tetrahedron method was designed to simulate how advanced chemometrics operates. In this paper, the development of the graphical tetrahedron and computational matrices derived from the possible tetrahedrons are discussed. The tetrahedron method was applied to four selected parameters obtained from nine illicit heroin samples. Pattern analysis and mathematical computation of the differences in areas for assessing the dissimilarity between the nine tetrahedrons were found to be user-convenient and straightforward for novice cluster analysts.
Fulltext Performance of Green Surfactants in the Formulation of Heavy-Duty Laundry Liquid Detergents (HDLD) with Special Emphasis on Palm Based Alpha Methyl Ester Sulfonates (α-MES)

Low SY, Tan JY, Ban ZH, Siwayanan P

J Oleo Sci, 2021 Aug 05;70(8):1027-1037.
PMID: 34248098 DOI: 10.5650/jos.ess21078

Liquid detergent has an increasing demand in North America, Western Europe, and Southeast Asia countries owing to its convenience to use and efficiency to clean. Alpha methyl ester sulfonates (α-MES), an anionic surfactant derived from palm oil based methyl ester, was reported to have lower manufacturing cost, good detergency with less dosage, excellent biodegradability, higher tolerance to hard water, and lower eco-toxicity as compared to linear alkylbenzene sulfonates (LABS). LABS was known as the workhorse of the detergent industry in the 20th century. Although palm-based α-MES was successfully used as the sole surfactant in powder detergent, there are still some unsettled technical issues related to phase stability and viscosity when using this anionic surfactant in heavy-duty laundry liquid detergent formulations. This paper will review not only the market overview of detergents, the application and performance of green surfactants in laundry detergents but also will highlight the technical issues related to the application of palm-based α-MES in laundry liquid detergent and some of the possible methods to overcome the formulation adversities.
Infantile intracardiac thrombus in severe encephalo-myocarditis

Woodhull S, Choo KK, Terumalay SD, Liew PS, Tan ZY

Med J Malaysia, 2021 Nov;76(6):956-959.
PMID: 34806696

Myocarditis is an uncommon disease in childhood and has a wide range of clinical presentations, from subtle to devastating and thus requires a high index of suspicion. Intracardiac thrombus formation following myocarditis is rare and thus its management remains challenging and not well defined. We report a child whom presented with a viral prodrome, rapidly deteriorated into multi organ failure and developed fulminant viral myocarditis with encephalitis that was complicated with an intracardiac thrombus formation. We describe the challenges faced, the successful medical treatment offered and propose factors that can help guide appropriate treatment.
Baby boy blue … and mommy too! A rare case of methaemoglobinaemia presenting simultaneously in a mother-neonate pair

Foong SC, Hwang YC, Foong WC, Tan ML

Med J Malaysia, 2021 Nov;76(6):924-926.
PMID: 34806687

Methaemoglobinaemia occurs when there is >1% methaemoglobin in erythrocytes. In an infant, they can present either congenitally or in an acquired form. We present a rare case of methaemoglobinaemia presenting simultaneously in a mother and infant pair. The mother and infant were discharged well on Day-4 post-delivery with both mother and baby recording oxygen saturation levels of 100%. On Day-7, during a routine clinic visit, they were incidentally found to be centrally cyanosed. There were no other abnormalities. On investigation, the methaemoglobin levels were elevated in the infant (23.9%) and mother (14.3%). Treatment with ascorbic acid normalised mother's methaemoglobin levels; but baby's levels remained high until the administration of oral methylene blue. Both baby and mother remained well and pink at last follow-up at 2 years 8 months of age. This case illustrates difficulties in ascertaining the cause of methaemoglobinaemia. Postdelivery, the mother-neonate pair were pink, and their haemoglobin electrophoresis were normal, hence it was unlikely to be congenital methaemoglobinaemia. The team could not identify any triggering factors for acquired methaemoglobinaemia. There was also the uncertainty of the necessity to treat the baby. This is because treatment is not without harmful effects and despite the high methaemoglobin levels, the infant was otherwise well. Only a single published paper recommended that high methaemoglobin levels must be treated, and the recommendation was not supported by evidence. Lessons learnt from our case are that neonates with methaemoglobinaemia can be safely treated with oral methylene blue, but more research is needed on the benefitrisk profile of treatment.
The effects of group art therapy on adolescents' self-concept and peer relationship: A mixed-method study

Huang CY, Su H, Cheng SM, Tan CS

New Dir Child Adolesc Dev, 2021 Sep;2021(179):75-92.
PMID: 34559460 DOI: 10.1002/cad.20435

This study examined the effects of group art therapy on self-concept and peer relationships among adolescents using a mixed-method approach. Twelve recruited adolescents from a high school in Northern Taiwan attended weekly 2-h group art therapy sessions for 8 weeks. Through a discovery-oriented approach incorporating focus group interviews and individual interviews, qualitative results revealed that the participants started getting to know themselves better and were able to explore their inner selves while noticing their own emotions. Their self-concept also became more positive along with reduced negative self-concept, increased positive self-concept, and clearer visions towards future goals. Furthermore, the therapy modified adolescents' negative peer relationships by reducing their social anxiety and adjusting their complicated experiences. Participants were found to experience trustable, allied, and compassionate positive peer relationships while having reduced loneliness and improved social skills at the same time. Besides, the participants answered self-concept and peer relationship scales at pre- and post-interventions as well as a 12-month follow-up thereafter. Friedman test on the longitudinal data showed participants reporting consistently higher self-concept and peer relationship at post-intervention and 12-month follow-up than at the pre-intervention stage. Taken together, the findings duly support art therapy in boosting adolescents' self-concept and peer relationships.
Fulltext Psychometric Evaluation of the Malay Version of the Family Adaptability and Cohesion Evaluation Scale III for Malaysian Adolescents

Cong CW, Tan CS, Noew HS, Wu SL

Int J Environ Res Public Health, 2021 Dec 24;19(1).
PMID: 35010416 DOI: 10.3390/ijerph19010156

The Family Adaptability and Cohesion Scale III (FACES-III) has been widely used to measure an individual's family functioning in terms of cohesion and adaptability. In Malaysia, the FACES-III has been translated into the Malay language for the community, but its psychometric properties in this context remain unknown. Thus, the purpose of this research is to examine the psychometric properties of the Malay version of the FACES-III in 852 adolescents attending secondary schools in Kuala Lumpur, Malaysia. Data were randomly split into two halves: the exploration sample and the validation sample. Exploratory factor analysis was conducted on the exploration sample and a two-factor model was discovered after removing nine items that showed low factor loading. Then, confirmatory factor analysis was conducted on the validation sample to compare the one-factor models, two-factor models, and three-factor models. Results showed that the 11-item two-factor model (FACES-III-M-SF) was superior to the other competing models. Both the exploratory and confirmatory factor analyses replicated the two-factor structure of the original version of FACES-III. The reliability of the overall scale was consistently good, but the subscale results were mixed. This suggests that researchers should use the overall score, but not the subscale scores, in analyses.
Fulltext Biocompatible graphene-zirconia nanocomposite as a cyto-safe immunosensor for the rapid detection of carcinoembryonic antigen

Lin LP, Tham SY, Loh HS, Tan MTT

Sci Rep, 2021 11 18;11(1):22536.
PMID: 34795382 DOI: 10.1038/s41598-021-99498-0

Graphene-based materials have gained remarkable attention in numerous disciplines owing to their unique electrochemical properties. Out of various hybridized nanocomposites, graphene-zirconia nanocomposite (GZ) was distinctive due to its biocompatibility. Zirconia nanoparticles serve as spacers that reduce the stacking of graphene and improve the electrochemical performance of the material. Considering that lungs and skin suffer the greatest exposure to nanoparticles, this study aimed to evaluate the cytotoxicity of the as-synthesized GZ nanocomposites on MRC5 (lung cells) and HaCaT (skin cells) via morphological observation and cell viability assay using 3-(4,5 dimethylthiazol-2-yl)-(2,5-diphenyltetrazolium bromide) tetrazolium (MTT). GZ-treated cells showed a comparable proliferation rate and morphology with untreated cells under microscopic evaluation. Based on MTT results, the IC50 values of GZ were > 500 µg/ml for MRC5 and HaCaT cells. The excellent biocompatibility was the supremacy of GZ over other nanocomposites applied as electrode materials in biosensors. GZ was functionalized with biolinker for the detection of carcinoembryonic antigen (CEA). The proposed immunosensor exhibited good responses towards CEA detection, with a 4.25 pg/ml LOD and correlation coefficient of R2 = 0.99 within a linear working range from 0.01 to 10 ng/ml. The performance of the immunosensor to detect CEA present in human serum was also evaluated. Good recovery of CEA was found, suggesting that the proposed immunosensor possess a high affinity to CEA even in a complex biological matrix, rendering it a promising sensing platform for real sample analysis and open a new way for the detection of cancer-associated proteins.
A South East Asian perspective of neuropsychiatric startle syndromes of latah

Lim TT, Tan K, Eow GB, Bhidayasiri R

Parkinsonism Relat Disord, 2022 Jan 26.
PMID: 35120841 DOI: 10.1016/j.parkreldis.2022.01.013

Latah is a culture-specific syndrome characterized by exaggerated startle response, echolalia, palilalia, echopraxia, coprolalia, forced obedience and involuntary vocalization in response to startle. Latah is stimulus-induced and is associated with behavior and psychiatric features. The aim of this review is to provide a comprehensive description on latah from a regional perspective based on previous literature and clinical experiences and highlight the clinical characteristics of latah from a movement disorders perspective. The pathophysiology of latah is complex and poorly understood although psychological stressors have been implicated. In view of the distressing psychosocial impact of latah, this neuropsychiatric startle syndrome warrants further studies to understand the pathophysiology and identify the appropriate treatments.
Fulltext Sclerosing odontogenic carcinoma - review of all published cases: is it a justifiable addition as a malignancy?

Lim D, Tan CC, Tilakaratne WM, Goh YC

Braz J Otorhinolaryngol, 2021 02 27;88(1):118-129.
PMID: 33715971 DOI: 10.1016/j.bjorl.2021.01.007

INTRODUCTION: Sclerosing odontogenic carcinoma was a new addition to the list of head and neck tumors by World Health Organization in 2017. This lesion has scarcely been reported and a lack of pathognomonic markers for diagnosis exists.
OBJECTIVE: The aim of the study was to summarize findings from the available literature to provide up-to-date information on sclerosing odontogenic carcinoma and to analyse clinical, radiological, and histopathological features to obtain information for and against as an odontogenic malignancy.
METHODS: We conducted a comprehensive review of literature by searching Pubmed, EBSCO and Web of Science databases, according to PRISMA guidelines. All the cases reported as sclerosing odontogenic carcinoma in English were included. Data retrieved from the articles were gender, age, clinical features, site, relevant medical history, radiographical findings, histopathological findings, immunohistochemical findings, treatments provided and prognosis.
RESULTS: Mean age at diagnosis of sclerosing odontogenic carcinoma was 54.4 years with a very slight female predilection. Sclerosing odontogenic carcinoma was commonly reported in the mandible as an expansile swelling which can be asymptomatic or associated with pain or paraesthesia. They appeared radiolucent with cortical resorption in radiograph evaluation. Histologically, sclerosing odontogenic carcinoma was composed of epithelioid cells in dense, fibrous, or sclerotic stroma with equivocal perineural invasion. Mild cellular atypia and inconspicuous mitotic activity were observed. There is no specific immunohistochemical marker for sclerosing odontogenic carcinoma. AE1/AE3, CK 5/6, CK 14, CK19, p63 and E-cadherin were the widely expressed markers for sclerosing odontogenic carcinoma. Surgical resection was the main treatment provided with no recurrence in most cases. No cases of metastasis were reported.
CONCLUSION: From the literature available, sclerosing odontogenic carcinoma is justifiable as a malignant tumor with no or unknown metastatic potential which can be adequately treated with surgical resection. However, there is insufficient evidence for histological grading or degree of malignancy of this tumor.
Vasorelaxant Action of the Chloroform Fraction of Orthosiphon stamineus via NO/cGMP Pathway, Potassium and Calcium Channels

Yam MF, Tan CS, Ahmad M, Ruan S

Am J Chin Med, 2016;44(7):1413-1439.
PMID: 27785939

Orthosiphon stamineus Benth. (Lamiaceae) is an important plant in traditional folk medicine that is used to treat hypertension and kidney stones. In humans, this plant has been tested as an addition regiment for antihypertensive treatment. Among the treatments for hypertension, O. stamineus had been to have diuretic and vasorelaxant effects in animal models. There is still very little information regarding the vasorelaxant effect of O. stamineus. Therefore, the present study was designed to investigate the vasorelaxant activity and mechanism of action of the fractions of O. stamineus. The vasorelaxant activity and the underlying mechanisms of the chloroform fraction of the 50% methanolic extract of O. stamineus (CF) was evaluated on thoracic aortic rings isolated from Sprague Dawley rats. CF caused relaxation of the aortic ring pre-contracted with phenylephrine in the presence and absence of endothelium, and pre-contracted with potassium chloride in endothelium-intact aortic ring. In the presence of endothelium, both indomethacin (a nonselective cyclooxygenase inhibitor) and [Formula: see text]-[1,2,4]Oxadiazolo[4,3-[Formula: see text]]quinoxalin-1-one (ODQ, selective soluble guanylate cyclase inhibitor) had a small effect on the vasorelaxation response. On the other hand, in the presence of Nω-nitro-L-arginine methyl ester (L-NAME, nitric oxide synthase inhibitor), methylene blue (cyclic guanosine monophosphate lowering agent), tetraethylammonium ([Formula: see text], nonselective calcium activator [Formula: see text] channel blocker), 4-aminopyridine (4-AP, voltage-dependent [Formula: see text] channel blocker), barium chloride ([Formula: see text], inwardly rectifying [Formula: see text] channel blocker), glibenclamide (nonspecific ATP-sensitive [Formula: see text] channel blocker), atropine (muscarinic receptor blocker) and propranolol (β-adrenergic receptor blocker), the vasorelaxant effect significantly reduced the relaxation stimulated by CF. CF was also found to be active in reducing [Formula: see text] release from the sarcoplasmic reticulum and blocking calcium channels.
Augmented pH-sensitivity absorbance of a ruthenium(ii) bis(bipyridine) complex with elongation of the conjugated ligands: an experimental and theoretical investigation

San Tan S, Yanagisawa S, Inagaki K, Morikawa Y, Kassim MB

Phys Chem Chem Phys, 2017 Sep 15.
PMID: 28913531 DOI: 10.1039/c7cp04268j

An absorbance-based sensor employing ruthenium bipyridyl with a phenanthroline-fused benzoylthiourea moiety formulated as [Ru(ii)(bpy)2(phen-nBT)](PF6)2 {bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, nBT = n-benzoylthiourea} has been synthesized and characterized by elemental analyses, mass spectrometry, and infrared, ultraviolet-visible, luminescence and nuclear magnetic resonance spectroscopy. The changes in the intensity of absorption and emission of the complex induced by functionalization of the benzoylthiourea ligands with amino and carbonyl in their protonated and deprotonated forms were studied experimentally. The absorption and emission properties of the complex exhibit a strong dependence on the pH (1-11) of the aqueous medium. This work highlights the pH-sensitivity augmentation of the absorption band by elongating the conjugation length in the structure of the ruthenium bipyridine complex. The principle of this work was to design the title compound to be capable of enhancing the differences in the absorption sensitivity responses towards pH between the protonated and deprotonated complexes in the absorption measurement. Along with significant and noticeable changes in the absorption spectra, subsequent theoretical investigations specifically on the electronic and absorbance properties of the title compound were carried out in this study. Protonation of the molecule significantly stabilized the lowest-unoccupied molecular orbital (LUMO), whereas the highest-occupied molecular orbital (HOMO) is greatly destabilized upon deprotonation. A time-dependent density functional theory (TDDFT) calculation in the linear-response (-LR) regime was performed to clarify the origin of the experimentally observed linear dependence of absorption intensity upon pH (1-11). The MLCT band exhibits hyperchromic shift at low pH as indicated by the large transition dipole moment and a wider distribution of the response charge of the molecule, which is induced by the stabilization of the electrostatic potential at the carbonyl moiety by protonation. This study provides the possibility of employing theoretical information to gain insight into the origin of the optical absorption obtained experimentally. The ruthenium complex was designed with an elongated ligand conjugation length and exhibited a tremendously large change in the absorption intensity of the protonated and deprotonated forms, which therefore demonstrates its feasibility as an indicator molecule especially for absorbance measurements.
Fulltext Refractive error, visual acuity, and corneal-curvature changes in high and low myopes with orthokeratology treatment: A Malaysian study

Liong SL, Mohidin N, Tan BW, Ali BM

Taiwan J Ophthalmol, 2015;5(4):164-168.
PMID: 29018692 DOI: 10.1016/j.tjo.2015.07.006

BACKGROUND/PURPOSE: The effect of orthokeratology (OK) on low myopia is well known, but there are a few reports on its effect on high myopia. In this study, the parametric changes in high and low myopia as results of wearing OK lenses for a period of 6 months have been analyzed.
METHODS: Records of schoolchildren (age 7-17 years) undergoing OK treatment from an optometry clinic were retrospectively reviewed. Data involving refractive errors, uncorrected visual acuity, and corneal curvatures at baseline and after 1 day, 1 week, 1 month, 3 months, and 6 months of OK treatment from 25 patients who fulfilled the inclusion criteria were examined. For the analysis, the participants were arbitrarily divided into two groups comprising high myopia (< -6.00 D) and low to moderate myopia (from -1.00 D to -6.00 D).
RESULTS: Significant reductions of refractive error, improvement in visual acuity, and corneal-curvature flattening were found in all participants after 6 months of OK lens wear compared to the baseline. No significant changes were found in corneal toricity in both high and low to moderate myopic groups. Almost all of these occurred after one night of lens wear in both the high- and low-myopia groups.
CONCLUSION: The OK lens wear significantly reduced the refractive error and corneal curvature that results in the improvement in visual acuity in both high- and low-myopia groups, and the reduction seemed to occur nearly at the same time despite the difference in initial myopic power. High myopes with refractive power up to -8.25 D would benefit significantly from OK lenses.
Study site: Optometry clinic, Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia
Fulltext Genomic Comparisons Reveal Microevolutionary Differences in Mycobacterium abscessus Subspecies

Tan JL, Ng KP, Ong CS, Ngeow YF

Front Microbiol, 2017;8:2042.
PMID: 29109707 DOI: 10.3389/fmicb.2017.02042

Mycobacterium abscessus, a rapid-growing non-tuberculous mycobacterium, has been the cause of sporadic and outbreak infections world-wide. The subspecies in M. abscessus complex (M. abscessus, M. massiliense, and M. bolletii) are associated with different biologic and pathogenic characteristics and are known to be among the most frequently isolated opportunistic pathogens from clinical material. To date, the evolutionary forces that could have contributed to these biological and clinical differences are still unclear. We compared genome data from 243 M. abscessus strains downloaded from the NCBI ftp Refseq database to understand how the microevolutionary processes of homologous recombination and positive selection influenced the diversification of the M. abscessus complex at the subspecies level. The three subspecies are clearly separated in the Minimum Spanning Tree. Their MUMi-based genomic distances support the separation of M. massiliense and M. bolletii into two subspecies. Maximum Likelihood analysis through dN/dS (the ratio of number of non-synonymous substitutions per non-synonymous site, to the number of synonymous substitutions per synonymous site) identified distinct genes in each subspecies that could have been affected by positive selection during evolution. The results of genome-wide alignment based on concatenated locally-collinear blocks suggest that (a) recombination has affected the M. abscessus complex more than mutation and positive selection; (b) recombination occurred more frequently in M. massiliense than in the other two subspecies; and (c) the recombined segments in the three subspecies have come from different intra-species and inter-species origins. The results lead to the identification of possible gene sets that could have been responsible for the subspecies-specific features and suggest independent evolution among the three subspecies, with recombination playing a more significant role than positive selection in the diversification among members in this complex.
Fulltext Effects of mandibular setback with or without maxillary advancement osteotomies on pharyngeal airways: An overview of systematic reviews

Tan SK, Leung WK, Tang ATH, Zwahlen RA

PLoS One, 2017;12(10):e0185951.
PMID: 29016682 DOI: 10.1371/journal.pone.0185951

BACKGROUND: Mandibular setback osteotomies potentially lead to narrowing of the pharyngeal airways, subsequently resulting in post-surgical obstructive sleep apnea (OSA).
OBJECTIVE: To summarize current evidence from systematic reviews that has evaluated pharyngeal airway changes after mandibular setback with or without concomitant upper jaw osteotomies.
METHODOLOGY: PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched with no restriction of language or date. Systematic reviews studying changes in pharyngeal airway dimensions and respiratory parameters after mandibular setback with or without concomitant upper jaw osteotomies have been identified, screened for eligibility, included and analyzed in this study.
RESULTS: Six systematic reviews have been included. While isolated mandibular setback osteotomies result in reduced oropharyngeal airway dimensions, the reduction is lesser in cases with concomitant upper jaw osteotomies. Only scarce evidence exists currently to what happens to naso- and hypo-pharyngeal airways. There is no evidence for post-surgical OSA, even though some studies reported reduced respiratory parameters after single-jaw mandibular setback with or without concomitant upper jaw osteotomies.
CONCLUSION: Although mandibular setback osteotomies reduce pharyngeal airway dimensions, evidence confirming post-surgical OSA was not found. Nevertheless, potential post-surgical OSA should be taken into serious consideration during the treatment planning of particular orthognathic cases. As moderate evidence exists that double-jaw surgeries lead to less compromised post-surgical pharyngeal airways, they should be considered as the method of choice especially in cases with severe dentoskeletal Class III deformity.
STUDY REGISTRATION: PROSPERO (registration number: CRD42016046484).

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