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Evaluation of heavy metals and environmental risk assessment in the Mangrove Forest of Kuala Selangor estuary, Malaysia
Get PDFThis study was carried out to evaluate the distribution, enrichment and ecological risk of heavy metals (arsenic (As), zinc (Zn), manganese (Mn), copper (Cu) and lead (Pb)) concentration in Kuala Selangor estuary at the Kuala Selangor Nature Park. The results suggested that As and Pb in sediment were as high as the background value, suggesting the presence of anthropogenic contamination. The risk assessment of sediment Igeo, CD, and PERI, on the other hand, showed low risk of heavy metals in Kuala Selangor estuary. Meanwhile, risk assessment code (RAC) results showed that Mn, As and Zn presented medium to high level of environmental risk. The translocation factor and bioaccumulation factors of heavy metal concentration by mangrove vegetation showed a variety of trends, which indicates the different partitioning and uptake ability of heavy metal in the tissues of different mangrove species. Therefore, underscores the importance of preserving the high diversity of mangroves at securing the health and productivity of the coastal region. These results may play a critical role in facilitating decision makers in managing the sustainability of mangrove forests
Venom proteomics and antivenom neutralization for the Chinese eastern Russell’s viper, Daboia siamensis from Guangxi and Taiwan
Get PDFThe eastern Russell's viper (Daboia siamensis) causes primarily hemotoxic envenomation. Applying shotgun proteomic approach, the present study unveiled the protein complexity and geographical variation of eastern D. siamensis venoms originated from Guangxi and Taiwan. The snake venoms from the two geographical locales shared comparable expression of major proteins notwithstanding variability in their toxin proteoforms. More than 90% of total venom proteins belong to the toxin families of Kunitz-type serine protease inhibitor, phospholipase A2, C-type lectin/lectin-like protein, serine protease and metalloproteinase. Daboia siamensis Monovalent Antivenom produced in Taiwan (DsMAV-Taiwan) was immunoreactive toward the Guangxi D. siamensis venom, and effectively neutralized the venom lethality at a potency of 1.41 mg venom per ml antivenom. This was corroborated by the antivenom effective neutralization against the venom procoagulant (ED = 0.044 ± 0.002 μl, 2.03 ± 0.12 mg/ml) and hemorrhagic (ED50 = 0.871 ± 0.159 μl, 7.85 ± 3.70 mg/ml) effects. The hetero-specific Chinese pit viper antivenoms i.e. Deinagkistrodon acutus Monovalent Antivenom and Gloydius brevicaudus Monovalent Antivenom showed negligible immunoreactivity and poor neutralization against the Guangxi D. siamensis venom. The findings suggest the need for improving treatment of D. siamensis envenomation in the region through the production and the use of appropriate antivenom
3′,4′-dihydroxyflavonol ameliorates endoplasmic reticulum stress-induced apoptosis and endothelial dysfunction in mice
Get PDFEndoplasmic reticulum (ER) stress has been implicated in the development of hypertension 3 through the induction of endothelial impairment. As 3′,4′-dihydroxyflavonol (DiOHF) 4 reduces vascular injury caused by ischaemia/reperfusion or diabetes, and flavonols have been demonstrated to attenuate ER stress, we investigated whether DiOHF can protect mice from ER stress-induced endothelial dysfunction. Male C57BLK/6 J mice were injected with tunicamycin to induce ER stress in the presence or absence of either DiOHF or tauroursodeoxycholic acid (TUDCA), an inhibitor of ER stress. Tunicamycin elevated blood pressure and impaired endothelium-dependent relaxation. Moreover, in aortae there was evidence of ER stress, oxidative stress and reduced NO production. This was coincident with increased NOX2 expression and reduced phosphorylation of endothelial nitric oxide synthase (eNOS) on Ser1176. Importantly, the effects of tunicamycin were significantly ameliorated by DiOHF or TUDCA. DiOHF also inhibited tunicamycin-induced ER stress and apoptosis in cultured human endothelial cells (HUVEC). These results provide evidence that ER stress is likely an important initiator of endothelial dysfunction through the induction of oxidative stress and a reduction in NO synthesis and that DiOHF directly protects against ER stress- induced injury. DiOHF may be useful to prevent ER and oxidative stress to preserve endothelial function, for example in hypertension
The capital structure decisions of Shariah compliant and non-compliant firms: Evidence from Malaysia
Get PDFThe capital structure puzzle remains largely unanswered Although some light have been shed on the dynamic forces that shapes the typrcal firm's debt-to-equrty moe, the case of the Sharrah-compliant firm's capital structure behaviour remains even more of a mystery. This paper attempts to investigate the capital structure behaviour of Shariah compliant firms of various levels as well those firms who are consistently Shariah non-compliant in Malaysia. The paper utilises a unique dataset of firms of heterogeneous level of Shariah-compliancy status over a 20 year period from the year 1997 to 2016. The paper focuses on the effects of dynamic forces behind capital structure variation such as the optimal capital structure behaviour based on the trade-off, pecking order, market timing and firm fixed effect models of capital structure. This study documents significant evidences in support of the trade-off theory with a hrgh speed of adjustment (SOA) as well as for the trme-invariant firm fixed effects across all Shariah compliancy group. Nevertheless, this study's findings show that there are evidences to suggest a moderate trend whereby as the Shariah compliancy group descend. stronger and stronger evidences of market timing behaviour appear amongst other thrngs. Thrs study suggests that segregating firms into different Shariah compliancy groups reveals a rich and diverse area of study which has never been delved in
Pure antimony film as saturable absorber for Q-switched erbium-doped fiber laser
No full textThis paper reports on the use of Antimony (Sb) polymer film to generate stable Q-switching pulses in Erbium-doped fiber laser (EDFL) cavity. The SA is fabricated by coating a thin layer of Sb on a polyvinyl alcohol (PVA) film through physical vapour deposition (PVD) process. A 1 × 1 mm area of the film SA is cut and integrated into between two fiber ferrules inside the laser cavity for intra-cavity loss modulation. Self-starting and stable Q-switched pulses are obtained within a pump power range from 60 to 142 mW. Within this range, the repetition rate increases from 70.82 to 98.04 kHz, while pulse width decreases from 7.42 to 5.36 μs. The fundamental frequency signal-to-noise ratio of the pulse signal is 74 dB, which indicates the excellent stability of the pulses. The maximum output power and pulse energy are 8.45 mW and 86.19 nJ, respectively. Our demonstration shows that Sb film SA capable of generating stable pulses train operating at 1.55-micron region
Distribution, genetic diversity and antimicrobial resistance of clinically important bacteria from the environment of a tertiary hospital in Malaysia
No full textObjectives
Hospital environments are potential reservoirs of bacteria associated with nosocomial infections. In this study, the distribution of cultivable environmental bacteria of clinical importance from a Malaysian tertiary hospital was determined and their resistotypes and genotypes were investigated.
Methods
Swab and fluid samples (n = 358) from healthcare workers’ hands, frequently touched surfaces, medical equipment, patients’ immediate surroundings, ward sinks and toilets, and solutions or fluids of 12 selected wards were collected. Biochemical tests, PCR and 16S rRNA sequencing were used for identification following isolation from CHROMagar™ Orientation medium. Clinically important bacteria such as Enterococcus spp., Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter spp., Pseudomonas aeruginosa and Enterobacter spp. were further characterised by disc diffusion method and rep-PCR.
Results
The 24 Gram-negative and 19 Gram-positive bacteria species identified were widely distributed in the hospital environment. Staphylococci were predominant, followed by Bacillus spp. and P. aeruginosa. Frequently touched surfaces, medical equipment, and ward sinks and toilets were the top three sources of bacterial species. Nine S. aureus, four Acinetobacter spp., one K. pneumoniae and one Enterobacter spp. were multidrug-resistant (MDR). The ESKAPE organisms were genetically diverse and widely dispersed across the hospital wards. A MDR MRSA clone was detected in a surgical ward isolation room.
Conclusion
The large variety of cultivable, clinically important bacteria, especially the genetically related MDR S. aureus, K. pneumoniae, Acinetobacter spp. and Enterobacter spp., from various sampling sites indicated that the surfaces and fomites in the hospital were potential exogenous sources of nosocomial infection in the hospital
Q-Switched Erbium-Doped Fiber Laser Using Cadmium Selenide Coated onto Side-Polished D-Shape Fiber as Saturable Absorber
No full textA stable Q-switched erbium doped fiber laser emitting at 1558nm is demonstrated using a cadmium selenide (CdSe) material coated onto a side-polished D-shape fiber as the saturable absorber (SA). By elevating the input pump power from the threshold of 91mW to the maximum available power of 136mW, a pulse train with a maximum repetition rate of 57.44 kHz, minimum pulse width of 3.76 μs, maximum average output power of 7.99mW, maximum pulse energy of 0.1391 μJ, and maximum peak power of 36.99mW are obtained. The signalto-noise ratio of the spectrum is measured to be around 75 dB. This CdSe based SA is simple, robust, and reliable, and thus suitable for making a portable pulse laser source
Does abuse in late life worsen sleep quality? A two-year prospective cohort study among rural older adults
No full textBackground: Elder abuse and neglect (EAN) is a growing public health problem, and numerous adverse health effects of abuse in late life have been documented. Little is known, however, about the impact of elder abuse on sleep quality. This study examines the longitudinal relationship between EAN and sleep quality. Methods: This was a 2-year prospective cohort study involving 1927 older adults in a rural Malaysian district, Kuala Pilah. A multi-stage cluster sampling strategy was employed. After 2 years, 1189 respondents were re-assessed. EAN was determined using the modified Conflict Tactic Scale, while sleep quality was measured using the Pittsburgh Sleep Quality Index (PSQI). Results: The prevalence of elder abuse was 8.1% (95% CI:6.9,9.3). Longitudinal analysis using generalized estimating equations showed that elder abuse contributed to higher PSQI scores (B:0.49, 95% CI:0.17,0.58). Sub-analyses demonstrated that psychological abuse and neglect had significant longitudinal relationships with increase of PSQI scores, while other subtypes did not. Conclusion: Abuse in late life, particularly psychological abuse and neglect, result in greater PSQI scores. Even though this may imply decline in sleep quality, our findings were not considered clinically significant as they did not exceed the clinical cut-off score of five. Nevertheless, sleep quality is an important determinant of health and a predictor of mortality among older adults; thus, understanding its relationship with abuse is useful to health care providers and policy-makers in improving health services and upgrading preventive measures
Bone Mineral Density and Associated Risk Factors among Female Athletes: A Cross-2 Sectional Study
No full textMenstrual irregularity and disordered eating were previously identified as risk factors for low bone mineral density (BMD) in female athletes. Therefore, an investigation for more potential factors that could be associated with low BMD among Malaysian female athletes is required. The aim of this study was to assess the association of BMD with energy availability, body weight, body fat, estrogen level and bone loading status in female athletes and to what extent those factors predict BMD. Energy intake and expenditure, body weight, Bone Physical Activity Questionnaire (BPAQ) score and estrogen level were determined from 85 female athletes aged 18-30 years in this cross-sectional study. Bone mineral density was measured by using an ultrasound bone densitometry device at the calcaneus bone. The female athletes’body weight and fat percentage were 56±9 kg and 27±6%, respectively and they were all eumenorrheic. Fifty three percent of them had low BMD (z- score < 0). Their mean energy intake (1291±33 kcal/day) was lower than energy expenditure (1807±34 kcal/day) which resulted in a low energy availability (29±1 kcal/day/kg FFM). BMD was positively associated with BPAQ score (r=0.4, p=0.000) and body weight (r=0.3, p=0.005) but negatively associated with energy expenditure (r=-0.4, p=0.000). There was no association of BMD with energy intake, energy availability, body fat percentage and estrogen level. In conclusion, BMD was associated with energy expenditure, body weight and BPAQ score among female athletes. Regression analysis showed that energy expenditure and BPAQ score were the main factors to predict BMD