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Fulltext Inter-simple sequence repeat (ISSR) markers: are we doing it right?

Ng, W. L., Tan. S.G.

ASM Science Journal, 2015;9(1):30-39.
MyJurnal

Inter-simple sequence repeats (ISSRs) are regions in the genome flanked by microsatellite sequences.
PCR amplification of these regions using a single primer yields multiple amplification products that can
be used as a dominant multilocus marker system for the study of genetic variation in various organisms.
ISSR markers are easy to use, low-cost, and methodologically less demanding compared to other
dominant markers, making it an ideal genetic marker for beginners and for organisms whose genetic
information is lacking. Here, we comment upon some of the intricacies often overlooked in designing an
ISSR experiment, clarify some misconceptions, and provide recommendations on using ISSR markers
in genetic variation studies.
Fulltext Minimally Invasive versus Conventional Open Surgery for Fixation of Spinal Fracture in Ankylosed Spine

Chung WH, Ng WL, Chiu CK, Chan C, Kwan MK

Malays Orthop J, 2020 Nov;14(3):22-31.
PMID: 33403059 DOI: 10.5704/MOJ.2011.005

Introduction: This was a retrospective study aimed to investigate the perioperative outcomes of long construct minimally invasive spinal stabilisation (MISt) using percutaneous pedicle screws (PPS) versus conventional open spinal surgery in the treatment of spinal fracture in ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH).
Material and Methods: Twenty-one patients with AS and DISH who were surgically treated between 2009 and 2017 were recruited. Outcomes of interest included operative time, intra-operative blood loss, complications, duration of hospital stay and fracture union rate.
Results: Mean age was 69.2 ± 9.9 years. Seven patients had AS and 14 patients had DISH. 17 patients sustained AO type B3 fracture and 4 patients had type B1 fracture. Spinal trauma among these patients mostly involved thoracic spine (61.9%), followed by lumbar (28.6%) and cervical spine (9.5%). MISt using PPS was performed in 14 patients (66.7%) whereas open surgery in 7 patients (33.3%). Mean number of instrumentation level was 7.9 ± 1.6. Mean operative time in MISt and open group was 179.3 ± 42.3 minutes and 253.6 ± 98.7 minutes, respectively (p=0.028). Mean intra-operative blood loss in MISt and open group was 185.7 ± 86.4ml and 885.7 ± 338.8ml, respectively (p<0.001). Complications and union rate were comparable between both groups.
Conclusion: MISt using PPS lowers the operative time and reduces intra-operative blood loss in vertebral fractures in ankylosed disorders. However, it does not reduce the perioperative complication rate due to the premorbid status of the patients. There was no significant difference in the union rate between MISt and open surgery.
Fulltext Discovery of novel genic-SSR markers from transcriptome dataset of an important non-human primate, Macaca fascicularis

Chang W, Ee-Uli J, Ng WL, Rovie-Ryan JJ, Tan SG, Yong CSY

Sci Rep, 2019 06 11;9(1):8504.
PMID: 31186469 DOI: 10.1038/s41598-019-44870-4

Macaca fascicularis, also known as the cynomolgus macaque, is an important non-human primate animal model used in biomedical research. It is an Old-World primate widely distributed in Southeast Asia and is one of the most abundant macaque species in Malaysia. However, the genetic structure of wild cynomolgus macaque populations in Malaysia has not been thoroughly elucidated. In this study, we developed genic-simple sequence repeat (genic-SSR) markers from an in-house transcriptome dataset generated from the Malaysian cynomolgus macaque via RNA sequencing, and applied these markers on 26 cynomolgus macaque individuals. A collection of 14,751 genic-SSRs were identified, where 13,709 were perfect SSRs. Dinucleotide repeats were the most common repeat motifs with a frequency of 65.05%, followed by trinucleotide repeats (20.55%). Subsequently, we designed 300 pairs of primers based on perfect di- and trinucleotide SSRs, in which 105 SSRs were associated with functional genes. A subset of 30 SSR markers were randomly selected and validated, yielding 19 polymorphic markers with an average polymorphism information content value of 0.431. The development of genic-SSR markers in this study is indeed timely to provide useful markers for functional and population genetic studies of the cynomolgus macaque and other related non-human primate species.
Morphometric sex determination of Milky and Painted Storks in captivity

Ong HK, Chinna K, Khoo SK, Ng WL, Wong BY, Chow KL, et al.

Zoo Biol, 2012 Mar-Apr;31(2):219-28.
PMID: 21480370 DOI: 10.1002/zoo.20387

Logistic regression was applied to develop a morphometric sexing method of two closely related stork species that were previously sexed through amplification of the CHD gene. Tarsus length (TL) and bill length (BL) measurements were recorded from captive populations of adult Milky Stork (Mycteria cinerea) (n = 60) and Painted Stork (Mycteria leucocephala) (n = 58) at Zoo Negara Malaysia. Despite having monomorphic plumages, both stork species exhibited normal sexual size dimorphism in which males were significantly larger than females in the tested variables. Based on logistic regression analysis, BL correctly classified the sex of sampled individuals from Painted and Milky stork with an overall predicted accuracy of 94.8 and 90.0%, respectively. However, TL measurements generated a lower predicted accuracy level of 86.2% and a same accuracy level of 90% on the sex classification of individuals from Painted and Milky stork, respectively. By comparing the measurements of both species, only the average BL measurements of the Milky storks were significantly lower than that of Painted storks (t-test, P80.001). The logistic regression equation in this study may serve as a simple and more practical option for sexing Milky and Painted storks for their breeding and conservation programmes.
Evening dosing versus morning dosing of antihypertensive medications for nocturnal hypertension: a systematic review and meta-analysis of 107 randomized controlled trials

Lee EK, Wang S, Ng WL, Ramdzan SN, Tse E, Chan L, et al.

J Hypertens, 2024 Oct 01;42(10):1653-1664.
PMID: 39196688 DOI: 10.1097/HJH.0000000000003783

Since the effects of once-daily antihypertensive (HT) medications are more pronounced within the first few hours of ingestion, evening administration of anti-HT medications can be a feasible treatment for nocturnal HT. However, no relevant meta-analysis has been conducted in patients with nocturnal HT. This meta-analysis included randomized controlled trials involving patients with elevated mean nocturnal blood pressure (BP) and compared evening anti-HT administration with morning administration. Multiple databases, including grey literature (e.g. clincialtrial.gov), were searched. Study selection and data extraction were conducted by two independent authors. Risk of bias assessment and overall quality of evidence were conducted using Cochrane risk-of-bias tool and GRADE by two independent authors. A total of 107 studies were included, 76 of which were investigated in China and had not been identified in previous reviews. Only one trial was ranked low risk-of-bias. Evening administration of anti-HT medications was effective in reducing nocturnal systolic BP (4.12-9.10 mmHg; I2 = 80.5-95.2%) and diastolic BP (3.38-5.87 mmHg; I2 = 87.4-95.6%). Subgroup analyses found that the effectiveness of evening administration was contributed by data from the Hermida group and China. Evening administration did not provide additional nocturnal/daytime/24-h BP reduction in non-Hermida/non-China studies (I2 = 0) and in meta-analyses that included studies with unclear or low risk of bias. The effectiveness of nocturnal BP reduction was similar across different types, doses, and half-lives of medications. Evening administration of anti-HT medications may reduce proteinuria, left ventricular hypertrophy (LVH), nondipping and morning surge. The overall quality of evidence was ranked as very low to low. Our results highlight the scarcity of low risk-of-bias studies and emphasize the need for such trials to evaluate the efficacy of evening dosing of anti-HT medications as a standard treatment for patients with nocturnal HT across diverse populations.