Comparative genomic and phylogenetic analysis of a toxigenic clinical isolate of Corynebacterium diphtheriae strain B-D-16-78 from Malaysia

In this study, we report the comparative genomics and phylogenetic analysis of Corynebacterium diphtheriae strain B-D-16-78 that was isolated from a clinical specimen in 2016. The complete genome of C. diphtheriae strain B-D-16-78 was sequenced using PacBio Single Molecule, Real-Time sequencing technology and consists of a 2,474,151-bp circular chromosome with an average GC content of 53.56%. The core genome of C. diphtheriae was also deduced from a total of 74 strains with complete or draft genome sequences and the core genome-based phylogenetic analysis revealed close genetic relationship among strains that shared the same MLST allelic profile. In the context of CRISPR-Cas system, which confers adaptive immunity against re-invading DNA, 73 out of 86 spacer sequences were found to be unique to Malaysian strains which harboured only type-II-C and/or type-I-E-a systems. A total of 48 tox genes which code for the diphtheria toxin were retrieved from the 74 genomes and with the exception of one truncated gene, only nucleotide substitutions were detected when compared to the tox gene sequence of PW8. More than half were synonymous substitution and only two were nonsynonymous substitutions whereby H24Y was predicted to have a damaging effect on the protein function whilst T262V was predicted to be tolerated. Both toxigenic and non-toxigenic toxin-gene bearing strains have been isolated in Malaysia but the repeated isolation of toxigenic strains with the same MLST profile suggests the possibility of some of these strains may be circulating in the population. Hence, efforts to increase herd immunity should be continued and supported by an effective monitoring and surveillance system to track, manage and control outbreak of cases.     

Population data and genetic characteristics of 12 X-STR loci using the Investigator® Argus X-12 Quality Sensor kit for the Kedayan population of Borneo in Malaysia

International Journal of Legal Medicine - DNA profiling of X-chromosomal short tandem repeats (X-STR) has exceptional value in criminal investigations, especially for complex kinship and incest...     

Prevalence and determinants of non-standard motorcycle safety helmets amongst food delivery workers in Selangor and Kuala Lumpur

BackgroundAlmost half of the global traffic crashes involve vulnerable groups such as pedestrian, cyclists and two-wheeler users. The main objective of this study was to determine the factors that influence standard of the safety helmets used amongst food delivery workers by presence of Standard and Industrial Research Institute of Malaysia (SIRIM) certification label.MethodsA cross sectional study was conducted amongst 150 food delivery workers from fast food outlets in the vicinity of Selangor and Kuala Lumpur. During observation, safety helmets were classified as standard safety helmet in the presence of SIRIM label and non-standard in the absence of the label. They were approached for questionnaire participation once consent was obtained and were requested to exchange their safety helmet voluntarily with a new one after the interview. Data analysis was carried out using SPSS. Chi square and logistic regression analysis was applied to determine the significance and odds ratio of the variables studied, respectively (penetration test, age, education level, knowledge, crash history, types of safety helmet, marital status and years of riding experience) against the presence of SIRIM label.ResultsThe response rate for this study was 85.2%. The prevalence of non-standard helmets use amongst fast food delivery workers was 55.3%. Safety helmets that failed the penetration test had higher odds of being non-standard helmets compared with safety helmets passing the test. Types of safety helmet indicated half-shell safety helmets had higher odds to be non-standard safety helmets compared to full-shell safety helmets. Riders with more years of riding experience were in high odds of wearing non-standard safety helmets compared to riders with less riding experience.ConclusionNon-standard (non-SIRIM approved) helmets were more likely to be half-shell helmets, were more likely to fail the standards penetration test, and were more likely to be worn by older, more experienced riders. The implications of these findings are discussed.     

CYP2A6 polymorphisms in Malays,Chinese and Indians

The genetically polymorphic cytochrome P450 (CYP) 2A6 is the major nicotine-oxidase in humans that may contribute to nicotine dependence and cancer susceptibility. The authors investigated the types and frequencies of CYP2A6 alleles in the three major ethnic groups in Malaysia and CYP2A6*1A, CYP2A6*1B, CYP2A6*1x2, CYP2A6*2, CYP2A6*3, CYP2A6*4, CYP2A6*5, CYP2A6*7, CYP2A6*8 and CYP2A6*10 were determined by allele-specific polymerase chain reaction (PCR) in 270 Malays, 172 Chinese and 174 Indians. Except for CYP2A6*2 and *3 that were not detected in the Malays and Chinese, all the other alleles were detected. Frequencies for the CYP2A6*4 allele were 7, 5 and 2%, respectively, in Malays, Chinese and Indians. A statistically significant high frequency of the duplicated CYP2A6*1x2 allele occurred among Chinese. Among Malays and Chinese, the most common allele was CYP2A6*1B, but it was CYP2A6*1A among Indians. These ethnic difference in frequencies suggested that further studies are required to investigate the implications on diseases such as cancer and smoking behaviour among these major ethnic groups in Malaysia.     

Swietenia macrophylla extract promotes the ability of Caenorhabditis elegans to survive Pseudomonas aeruginosa infection

Ethnopharmacological relevance

Swietenia macrophylla or commonly known as big leaf mahogany, has been traditionally used as an antibacterial and antifungal agent.

Aim of the study

The unwanted problem of antibiotic resistance in many bacterial species advocates the need for the discovery of the new anti-infective drugs. Here, we investigated the anti-infective properties of Swietenia macrophylla with an assay involving lethal infection of Caenorhabditis elegans with the opportunistic human pathogen Pseudomonas aeruginosa.

Materials and methods

Using a slow killing assay, Caenorhabditis elegans was challenged with an infective strain of Pseudomonas aeruginosa (PA14). The ability of Swietenia macrophylla seed ethyl acetate extract to promote the survival of infected worms was assessed by comparing the percentage of survival between extract treated and non-treated worm populations. The effect of Swietenia macrophylla towards PA14 growth, Caenorhabditis elegans feeding rate and degree of PA14 colonization in the worm gut was also evaluated. Lastly, using a fluorescent transgenic Caenorhabditis elegans strain and real time PCR, the effect of Swietenia macrophylla on the expression of lys-7, an immune response gene was also investigated.

Results

Our results demonstrate the ability of Swietenia macrophylla seed ethyl acetate extract in rescuing Caenorhabditis elegans from fatal PA14 infection. Consequently, we showed that the extract promotes the survival without exhibiting any bactericidal effect or perturbation of Caenorhabditis elegans feeding rate. We also showed that Swietenia macrophylla was able to restore the initially repressed lys-7 level in PA14 infected Caenorhabditis elegans.

Conclusion

Swietenia macrophylla extract is able to enhance the ability of Caenorhabditis elegans to survive PA14 infection without directly killing the pathogen. We further showed that the extract boosted the expression of a gene pivotal for innate immunity in Caenorhabditis elegans. Collectively, these findings strongly suggest the presence of compounds within Swietenia macrophylla seed that either reduces Pseudomonas aeruginosa virulence and/or enhance host resistance.     

The effect of mitragynine on cAMP formation and mRNA expression of mu-opioid receptors mediated by chronic morphine treatment in SK–N–SH neuroblastoma cell

Ethopharmacological relevance

Mitragynine is an indole alkaloid compound of Mitragyna speciosa (M. speciosa) Korth. (Rubiaceae). This plant is native to the southern regions of Thailand and northern regions of Malaysia and is frequently used to manage the withdrawal symptoms in both countries.

Aim of study

To investigate the effect of mitragynine after chronic morphine treatment on cyclic AMP (cAMP) level and mRNA expression of mu-opioid receptor (MOR) in human neuroblastoma SK–N–SH cell.

Method and Materials

Mitragynine was isolated from the Mitragyna speciosa plant using the acid–base extraction method. The cAMP level upon forskolin stimulation in the cells was determined using the Calbiochem^® Direct Immunoassay Kit. The mRNA expression of the MOR was carried out using quantitative RT-PCR.

Result

Cotreatment and pretreatment of morphine and mitragynine significantly reduced the production of cAMP level at a lower concentration of mitragynine while the higher concentration of this compound could lead to the development of tolerance and dependence as shown by the increase of the cAMP level production in foskolin stimulation. In MOR mRNA expression study, cotreatment of morphine with mitragynine significantly reduced the down-regulation of MOR mRNA expression as compared to morphine treatment only.

Conclusion

These finding suggest that mitragynine could possibly avoid the tolerance and dependence on chronic morphine treatment by reducing the up-regulation of cAMP level as well as reducing the down-regulation of MOR at a lower concentration of mitragynine.     

Distribution of cytokine gene polymorphisms in five Malay subethnic groups in Peninsular Malaysia

In this survey, we have successfully genotyped 22 single nucleotide polymorphisms in the 13 cytokine genes for five Malay subethnic groups (Kelantan, Acheh, Mandailing, Minangkabau and Patani Malays) using polymerase chain reaction–sequence‐specific primer cytokine genotyping kit (Invitrogen, Carlsbad, CA, USA). Most of the cytokine genes showed similar pattern of allelic spectra with wild‐type alleles (e.g. ILIa?889/C, ILIB+3962/C and IL6 nt565/G) that represent more than 80% in the studied Malay subethnic groups. These newly observed cytokine alleles and subsequent analyses clearly indicate genetic contribution from Asia in the studied Malay subethnic groups with evidence of admixture from neighbouring populations in Patani Malays. The cytokine data sets for the five Malay subethnic groups deposited in this report can also be used as reference standard for searching suitable donor for allograft transplant and diseases association study. This is particularly relevance as our analyses showed differences between the Malay subethnic groups and other populations screened for cytokine genes.