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Laboratory and field tests of temephos (AbateR) on mosquito larvae and non-target organisms in rice fields in Malaysia

Yap HH, Lau BL, Leong YP

Southeast Asian J Trop Med Public Health, 1982 Dec;13(4):646-53.
PMID: 6189198

The toxic effects of Abate (temephos) on mosquito larvae and non-target organisms were studied in the rice-field and in the laboratory. In the laboratory tests, Culex tritaeniorhychus larvae and cladoceran zooplanktons (predominantly Diaphanosoma and Moinodaphnia species) were found to be highly susceptible to Abate with LC50 values of 0.27 and less than 0.10 parts per billion respectively. Other non-target species in decreasing degree of susceptibility to Abate were copepods (Tropodiaptomus spp.), Aplocheilus panchax and Tubifex worms. In field study, Abate at concentrations 60, 100 and 200 gm hectare-1 is effective in maintaining the rice-fields free of Anopheles and Culex mosquitoes for at least 2 days. No mortality was observed for Aplocheilus panchax and Tubifex worms at the above concentrations; nevertheless, populations of cladoceran zooplanktons and copepods were reduced up to seven days posttreatment.
Factors affecting diagnostic yield in stereotactic biopsy for brain lesions: a 5-year single-center series

Lau BL, Vijian K, Liew DNS, Wong ASH

Neurosurg Rev, 2021 Oct 10.
PMID: 34628562 DOI: 10.1007/s10143-021-01671-6

The objective of this study is to determine the factors that are associated with the diagnostic yield of stereotactic brain biopsy. A retrospective analysis was performed on 50 consecutive patients who underwent stereotactic brain biopsies in a single institute from 2014 to 2019. Variables including age, gender, lesion topography and characteristics, biopsy methods, and surgeon's experience were analyzed along with diagnostic rate. This study included 31 male and 19 female patients with a mean age of 48.4 (range: 1-76). Of these, 25 underwent frameless brain-suite stereotactic biopsies, 15 were frameless Portable Brain-lab® stereotactic biopsies and 10 were frame-based CRW® stereotactic biopsies. There was no statistical difference between the diagnostic yield of the three methods. The diagnostic yield in our series was 76%. Age, gender, and biopsy methods had no impact on diagnostic yield. Periventricular and pineal lesion biopsies were significantly associated with negative diagnostic yield (p = 0.01) whereas larger lesions were significantly associated with a positive yield (p = 0.01) with the mean volume of lesions in the positive yield group (13.6 cc) being higher than the negative yield group (7 cc). The diagnostic yields seen between senior and junior neurosurgeons in the biopsy procedure were 95% and 63%, respectively (p = 0.02). Anatomical location of the lesion, volume of the lesion, and experience of the surgeon have significant impacts on the diagnostic yield in stereotactic brain biopsy. There was no statistical difference between the diagnostic yield of the three methods, age, gender, and depth of lesion.
Fulltext Brain and spinal tumour

Goh CH, Lu YY, Lau BL, Oy J, Lee HK, Liew D, et al.

Med J Malaysia, 2014 Dec;69(6):261-7.
PMID: 25934956 MyJurnal

This study reviewed the epidemiology of brain and spinal tumours in Sarawak from January 2009 till December 2012. The crude incidence of brain tumour in Sarawak was 4.6 per 100,000 population/year with cumulative rate 0.5%. Meningioma was the most common brain tumour (32.3%) and followed by astrocytoma (19.4%). Only brain metastases showed a rising trend and cases were doubled in 4 years. This accounted for 15.4% and lung carcinoma was the commonest primary. Others tumour load were consistent. Primitive neuroectodermal tumour (PNET) and astrocytoma were common in paediatrics (60%). We encountered more primary spinal tumour rather than spinal metastases. Intradural schwannoma was the commonest and frequently located at thoracic level. The current healthcare system in Sarawak enables a more consolidate data collection to reflect accurate brain tumours incidence. This advantage allows subsequent future survival outcome research and benchmarking for healthcare resource planning.
Psychological symptoms among healthcare workers handling COVID-19 patients

Sim SK, Lau BL, Zaila SR, Hazira N, Aniqah NM, Panicker J, et al.

Med J Malaysia, 2021 03;76(2):138-144.
PMID: 33742619

INTRODUCTION: Healthcare workers serve as the frontliners against the coronavirus 2019 disease (COVID-19) and this puts them most at risk of infection as they attend to numerous patients with unknown status. This study aimed to examine stress, anxiety, and depression among healthcare workers caring for COVID-19 patients in Sarawak General Hospital (SGH), Malaysia.
MATERIALS AND METHODS: This cross-sectional observational study conducted in SGH during the pandemic with an online self-administered questionnaire composed of two parts, the socio-demographic characteristics, and the Depression Anxiety Stress Scale (DASS).
RESULTS: A total of 105 healthcare workers responded to this study. A questionnaire in both Bahasa Melayu and English was used. The findings showed that all healthcare workers had mild anxiety, with the majority experiencing mild stress (57.1%), and almost half of the respondents experiencing mild depression (41%). Female subjects had a significant higher mean score in anxiety level and stress level compared to male subjects (10.0±3.20 vs. 8.6±2.93, p<0.05; 14.1±4.76 vs. 10.7±3.70, p<0.05, respectively). Staff who were transferred from other units to handle COVID-19 cases experienced more psychological symptoms. There were significant correlations between the depression, anxiety and stress levels among the healthcare workers and the number of children they had (r=0.739, p=0.001; r=0.642, p=0.001; r=1, p =0.001 respectively). However, the stress level among the healthcare workers was reversely correlated with their years of working experience (r=-0.199, p=0.042).
CONCLUSION: This study identified some socio-demographic factors associated with increased levels of stress, anxiety and depression among the healthcare workers during pandemic, which may lay ground for future interventions.
Comparing the outcome of monitored anaesthesia care and local anaesthesia for carpal tunnel syndrome surgery by neurosurgeons

Goh CH, Lau BL, Teong SY, Law WC, Tan CS, Vasu R, et al.

Med J Malaysia, 2019 12;74(6):499-503.
PMID: 31929475

INTRODUCTION: Carpal tunnel syndrome (CTS) is the commonest median nerve entrapment neuropathy of the hand, up to 90% of all nerve compression syndromes. The disease is often treated with conservative measures or surgery. The senior author initially intended to treat his own neurosurgical patients concurrently diagnosed with carpal tunnel syndrome in 2014, subsequently, he began to pick up more referrals from the primary healthcare group over the years. This has led to the setup of a peripheral and spine clinic to act as a hub of referrals.
OBJECTIVE: Department of Neurosurgery Sarawak aimed to evaluate the surgical outcome of carpal tunnel release done over five years.
METHODS: The carpal tunnel surgeries were done under local anaesthesia (LA) given by neurosurgeons (Bupivacaine 0.5% or Lignocaine 2%). Monitored anaesthesia care (MAC) was later introduced by our hospital neuroanaesthetist in the beginning of 2018 (Target-controlled infusion propofol and boluses of fentanyl). We looked into our first 17 cases and compared these to the two anaesthesia techniques (LA versus MAC + LA) in terms of patient's pain score based on visual analogue scale (VAS).
RESULTS: Result showed MAC provided excellent pain control during and immediately after the surgery. None experienced anaesthesia complications. There was no difference in pain control at post-operation one month. Both techniques had equal good clinical outcome during patients' clinic follow up.
CONCLUSION: Neurosurgeons provide alternative route for CTS patients to receive surgical treatment. Being a designated pain free hospital, anaesthetist collaboration in carpal tunnel surgery is an added value and improves patients overall experience and satisfaction.
Introduction of a newly created AW stereotactic frame: a phantom-based accuracy evaluation and an initial experience in clinical usage

Lau BL, Idris Z, Abdullah JM, Bujang MA, Wong ASH

Br J Neurosurg, 2023 Dec;37(6):1572-1579.
PMID: 33191803 DOI: 10.1080/02688697.2020.1837728

BACKGROUND: A new stereotactic frame was created in 2015, based on a linear algorithm. It is called Albert Wong (AW) frame. A simple AW stereo-calculator was also designed based on Excel® (Microscoft Corporation, Redmond, WA) programme for the frame.
OBJECTIVE: The aim of this study is to test the accuracy of the AW frame by a direct head to head comparison with CRW® frame (Integra Life Sciences, Plainsboro, NJ) on a phantom.
METHODS: This is a prospective pilot cross-sectional phantom study with a total of 42 (21 for AW and 21 for CRW®) laboratory testings performed in 2017 at our institute to compare the accuracies of both frames in a consecutive manner. A phantom (BL phantom) was newly created, where targets can be placed at different heights and positions on a platform attached under the frame for accuracy testing comparing between the AW and CRW® frames.
RESULTS: A comparable accuracy testing results were observed between the AW and CRW® frames of 0.64 mm versus 1.07 mm respectively. Approval from the local ethics committee for a clinical trial was obtained. We report on three case illustrations who had the AW frame-based biopsies with definitive diagnoses and without any post-biopsy related complication.
CONCLUSION: AW frame successfully demonstrated a good accuracy of 0.64 mm in phantom testing using the BL phantom by a linear algorithmic calculation. The clinical trial with three patients demonstrated definitive diagnoses and safety with its use.
Improving Diagnostic Yield and Accuracy of Stereotactic Biopsies through Changes in Practice and Techniques: An 8-Year Single-Center Comparative Study

Vijian K, Lau BL, Kanesen D, Lim SS, Ngian DL, Wong ASH

Asian J Neurosurg, 2024 Dec;19(4):701-706.
PMID: 39606292 DOI: 10.1055/s-0044-1789593

Background Stereotactic biopsies are used to aid neurosurgeons in clinching the diagnosis of intracranial lesions that are difficult to access surgically. A published study of stereotactic biopsies in our center demonstrated a diagnostic yield of only 76% for biopsies from the year 2014 to 2019. A set of criteria/prerequisites was applied to increase yield. Objective The aim of the study was to identify the improvement in accuracy and yield after implementation of a set of criteria/prerequisites. Materials and Methods This was a retrospective and prospective analysis of all patients who underwent stereotactic biopsies from the year 2014 to 2022. This study was conducted at Sarawak General Hospital, Malaysia. A set of stereotactic criteria/prerequisites was introduced since 2020, which include preoperative careful, meticulous trajectory planning and target selection, regular checking and maintenance of equipment, larger burr holes, and good sampling techniques. Results A total of 83 patients underwent stereotactic biopsies from the year 2014 to 2022. Frameless and frame-based methods were used for 45 (54%) and 38 (46%) patients, respectively. The overall diagnostic yield of all biopsies was 84%. Fifty patients underwent stereotactic biopsies prior to implementation of good practice guidelines in 2020 with a positive histopathological yield and accuracy of 76 and 88%, respectively. Thirty-three biopsies done postimplementation demonstrated a yield and accuracy of 97% ( p
Does Putting Back Hyperostotic Bone Flap in Meningioma Surgery Cause Tumor Recurrence? An Observational Prospective Study

Lau BL, Che Othman MI, Fathil MFMD, Liew DNS, Lim SS, Bujang MA, et al.

World Neurosurg, 2019 Jul;127:e497-e502.
PMID: 30926555 DOI: 10.1016/j.wneu.2019.03.183

BACKGROUND: Replacing the skull defect with synthetic materials for hyperostotic bone secondary to meningioma is recommended owing to the possibility of tumor invasion. In our institution, neurosurgeons have been putting back the refashioned hyperostotic bone flap after meningioma excision because of budget constraints. The aim of this study was to review the long-term meningioma recurrence rate in these patients.
METHODS: This was a nonrandomized, prospective observational study conducted from September 2011 to January 2015 on patients with intracranial convexity and parasagittal meningiomas. Preoperative computed tomography brain scans were obtained in all patients to confirm bony hyperostosis. Intraoperatively, part of the hyperostotic bone was sent for histopathologic examination. The rest of the bone flap was refashioned by drilling off the hyperostotic part. The bone flap was put back over the craniotomy site after soaking in distilled water. All patients were followed up for tumor recurrence.
RESULTS: The study included 34 patients with convexity or parasagittal meningioma World Health Organization grade I-II who underwent Simpson grade Ia and IIa excision. Median follow-up was 63.5 months (mean 64.9 ± 9.4 months). The hyperostotic bone flap showed presence of tumor in 35% of patients. There were 2 patients with parasagittal meningiomas after Simpson grade IIa resections who developed tumor recurrences.
CONCLUSIONS: Our study found that meningioma recurrence was unlikely when autologous cranioplasty was done with refashioned hyperostotic bone. This could be done in the same setting with meningioma excision. There was no recurrence in convexity meningiomas at mean 5-year follow-up.