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Malaysian child psychiatric practice: a pragmatic and rational approach

Yeoh KL, Ong SB

Aust N Z J Psychiatry, 1982 Jun;16(2):61-6.
PMID: 6957184

A pragmatic and rational approach to the management of five child psychiatric cases in Malaysia is briefly reviewed. The significance of sociocultural factors in treating these cases within the context of a rapidly developing plural society is emphasized. The implications of overemphasis on educational and material achievements are noted.
Fulltext Global case studies for chronic kidney disease/end-stage kidney disease care

Yang CW, Harris DCH, Luyckx VA, Nangaku M, Hou FF, Garcia Garcia G, et al.

Kidney Int Suppl (2011), 2020 Mar;10(1):e24-e48.
PMID: 32149007 DOI: 10.1016/j.kisu.2019.11.010

The prevalence of chronic kidney disease and its risk factors is increasing worldwide, and the rapid rise in global need for end-stage kidney disease care is a major challenge for health systems, particularly in low- and middle-income countries. Countries are responding to the challenge of end-stage kidney disease in different ways, with variable provision of the components of a kidney care strategy, including effective prevention, detection, conservative care, kidney transplantation, and an appropriate mix of dialysis modalities. This collection of case studies is from 15 countries from around the world and offers valuable learning examples from a variety of contexts. The variability in approaches may be explained by country differences in burden of disease, available human or financial resources, income status, and cost structures. In addition, cultural considerations, political context, and competing interests from other stakeholders must be considered. Although the approaches taken have often varied substantially, a common theme is the potential benefits of multistakeholder engagement aimed at improving the availability and scope of integrated kidney care.
Fulltext Study protocol for an open labelled randomised controlled trial of perioperative oral nutrition supplement in breast and colorectal cancer patients undergoing elective surgery

Wong TX, Chen ST, Ong SH, Shyam S, Kandasami P, Chee WSS

Trials, 2021 Nov 03;22(1):767.
PMID: 34732233 DOI: 10.1186/s13063-021-05716-5

BACKGROUND: While it is well established that perioperative use of oral nutrition supplement (ONS) improves nutrition status among severely malnourished surgical cancer patients, the evidence requires further substantiation for non-severely malnourished patients with cancer. This protocol paper presents the rationale and design of a randomised controlled trial to evaluate the effectiveness of preoperative as well as an extended 90-day postoperative use of ONS on nutritional and clinical outcomes among patients undergoing elective surgery for breast and colorectal cancer.
METHODS: Patients with primary breast and colorectal cancer undergoing elective surgery are recruited from two tertiary hospitals. Eligible patients are assigned into one of the three intervention arms: (i) Group SS will receive ONS in addition to their normal diet up to 14 days preoperatively and postoperatively up to discharge; (ii) Group SS-E will receive ONS in addition to their normal diet up to 14 days preoperatively, postoperatively up to discharge and for an extended 90 days after discharge; and (iii) Group DS will receive ONS in addition to their normal diet postoperatively up to discharge from the hospital. The ONS is a standard formula fortified with lactium to aid in sleep for recovery. The primary endpoints include changes in weight, body mass index (BMI), serum albumin and prealbumin levels, while secondary endpoints are body composition (muscle and fat mass), muscle strength (handgrip strength), energy and protein intake, sleep quality, haemoglobin, inflammatory markers (transferrin, high sensitivity C-reactive protein, interleukin-6), stress marker (saliva cortisol), length of hospital stay and postoperative complication rate.
DISCUSSION: This trial is expected to provide evidence on whether perioperative supplementation in breast and colorectal cancer patients presenting with high BMI and not severely malnourished but undergoing the stress of surgery would be beneficial in terms of nutritional and clinical outcomes.
TRIAL REGISTRATION: ClinicalTrial.gov NCT04400552. Registered on 22 May 2020, retrospectively registered.
Fulltext Disruption of adeB gene has a greater effect on resistance to meropenems than adeA gene in Acinetobacter spp. isolated from University Malaya Medical Centre

Wong EW, Yusof MY, Mansor MB, Anbazhagan D, Ong SY, Sekaran SD

Singapore Med J, 2009 Aug;50(8):822-6.
PMID: 19710984

The AdeABC pump of Acinetobacter spp. confers resistance to various antibiotic classes. This pump is composed of the AdeA, AdeB, and AdeC proteins where AdeB is a member of the resistance-nodulation-division efflux pump superfamily. The adeA, adeB, and adeC genes are contiguous and adjacent to adeS and adeR, which are transcribed in the opposite direction and which specify proteins homologous to sensors and regulators of two-component systems, respectively. In this study, an attempt is made to elucidate the role of the AdeABC efflux pump in carbapenem resistance in Acinetobacter spp.
Genetic variability of Blastocystis sp. isolates obtained from cancer and HIV/AIDS patients

Tan TC, Ong SC, Suresh KG

Parasitol Res, 2009 Oct;105(5):1283-6.
PMID: 19603182 DOI: 10.1007/s00436-009-1551-5

This represents the first study to determine the genetic diversity of Blastocystis sp. among cancer and HIV/AIDS patients. Forty Blastocystis sp. isolates obtained from 20 cancer and 20 HIV/AIDS patients were genotyped by PCR using seven pairs of known sequenced-tagged site primers. Out of the 40 isolates, 38 were identified as one of the known genotypes and two isolates were negative with all the STS primers. Blastocystis sp. subtype 3 which is reported to be associated with disease was found to be predominant among the study subjects.
Fulltext Isolated Ascites in a Monochorionic Twin after Fetoscopic Laser Ablation Is Not Necessarily Secondary to Recurrence or Anaemia: Bowel Complications in Twin-to-Twin Transfusion Syndrome after Fetoscopic Laser Ablation

Tan LN, Cheung KW, Philip I, Ong S, Kilby MD

Fetal Diagn Ther, 2019;45(5):285-294.
PMID: 30554214 DOI: 10.1159/000494616

BACKGROUND/PURPOSE: We report a case study of jejunal atresia and the results of a systematic literature review of all reported cases of bowel complications occurring after fetoscopic laser ablation (FLA) for the treatment of twin-to-twin transfusion syndrome (TTTS).
METHODS: A systematic literature review was performed of bowel complications after FLA for TTTS according to PRISMA guidelines.
RESULTS: There are 11 published cases of small bowel atresia, 5 cases of necrotising enterocolitis (NEC), and 2 cases with foetal bowel perforations. Recipient twins were more likely to be affected by small bowel atresia (7 recipient and 4 donor cases) and NEC (3 recipient and 2 donor twins). Prenatal ultrasonographic abnormalities were demonstrated in 7 out of 9 cases with bowel atresia and in both cases of bowel perforation. The overall survival rate for neonates with bowel complications after FLA is 72%, but is much lower for co-twins at 22%. The survival rates for jejunoileal atresia and NEC are 91 and 40%, respectively.
CONCLUSIONS: It is uncertain as to whether these bowel anomalies are due to bowel ischaemia associated with TTTS, the treatment with FLA, or a combination of both. Cases with prenatal abdominal ultrasonographic abnormalities after FLA should have close prenatal and postnatal assessment to detect bowel complications.
The influence of enclosure design on diurnal activity and stereotypic behaviour in captive Malayan Sun bears (Helarctos malayanus)

Tan HM, Ong SM, Langat G, Bahaman AR, Sharma RS, Sumita S

Res Vet Sci, 2013 Apr;94(2):228-39.
PMID: 23141171 DOI: 10.1016/j.rvsc.2012.09.024

The effect of enclosure design on diurnal activity and stereotypic behaviour was assessed in 17 adult Malayan Sun bears (Helarctos malayanus), kept either in barren indoor enclosures or relatively enriched outdoor enclosures. Locomotion was the most frequent activity observed in the indoor bears, followed by resting. In contrast, conspecifics housed outdoors spent most of the time resting. Eleven forms of stereotypic behaviours were recorded in the bears, with pacing being the most common. The frequency and repertoire of stereotypies were significantly higher in the indoor bears irrespective of enclosure size. Novel forms of locomotor (forward-reverse pacing) and oral (allo-sucking) stereotypies were recorded. Oral stereotypies were predominant in the bears housed indoors, while patrolling was confined to the outdoor bears. Enclosure complexity significantly influences activity budget and occurrence of stereotypic behaviours, highlighting the importance of appropriate enclosure design and enrichment for the welfare of captive bears.
Rheumatoid arthritis: case review from MOH collaborative rheumatology centers in Malaysia. [Abstract]

Sulaiman W, Othman M, Mokhtar AM, Rosman A, Ong SG, Soo IS, et al.

APLAR Journal of Rheumatology, 2006;9 Suppl 1:A54-A55.
DOI: 10.1111/j.1479-8077.2006.00199_24.x

Objective: To determine the number of RA cases and to evaluate the demographic patterns in all 4 Rheumatology Referral Centers under the Ministry of Health Malaysia. Materials and methods: One thousand and eighty-four rheumatoid arthritis patients from all 4 centers i.e. Hospital Selayang, Putra Jaya, Seremban and Taiping which are situated in the west coast of West Malaysia, using rheumatoid arthritis database comprising of basic clinical and patient questionnaire, until the end of year 2004 were analysed. Results: At the time of documentation, 88.6% were female at all range of ages especially between age of 25 and 54 years (77.6%) with female to male ratio 8 :1. 52.1% were housewives. Mean age of onset of RA was 49.6 Â± 11.8 SD with female 49.3 Â± 11.7 SD and male 52.0 Â± 12.0 SD (p < 0.05). Indian was the predominant ethnic group (54.5%), followed by Malay (31.4%), Chinese (11.6%) and others (27%). Majority had their education up to secondary level (50.8%), followed by primary (32.6%), and tertiary (6.3%) levels while 10.3% of cases had not received any formal education in their lives. 74.4% were seropositive and 87.3% fulfilled at least 4 out of 7 American College of Rheumatology (ACR) revised criteria for rheumatoid arthritis. 74% were diagnosed RA within 2 years after the onset of arthritis. Seropositivity was not significantly related to gender. Positive rheumatoid factor was dominated by Indian followed by Malay and Chinese. 83.3% were married. 23.3% female and 33.9% male between age group 25-54 were employed. 7.4% had achieved their retirement at time of entry whilst 8.9% were unemployed. Employment status was statistically significant across gender (p < 0.001). The cases differed between rheumatology centers as well as individual practices. Conclusion: There are increasing numbers of RA cases in Malaysia. Results from this study did not reflect the true prevalence of RA in Malaysia. Hence, a larger and more comprehensive database on RA with collaboration of all Government and Private Hospitals in the whole nation will provide better information about the patient case mix in different healthcare settings, treatment practice as well as disease complications. The implementation of rheumatology centers with better regional cooperation, will lead to better treatment and outcome in terms of identification of early as well as established RA cases. Early referral to the centers will be made possible for proper treatment institution and rehabilitation. Hence, improve quality of life including socio-economic status especially among those within the productive age.
Sublingual immunotherapy in patients with house dust mite allergic rhinitis: prospective study of clinical outcomes over a two-year period

Soh JY, Thalayasingam M, Ong S, Loo EX, Shek LP, Chao SS

J Laryngol Otol, 2016 Mar;130(3):272-7.
PMID: 26781592 DOI: 10.1017/S0022215116000025

BACKGROUND: Sublingual immunotherapy in patients with allergic rhinitis sensitised to house dust mites is safe, but its efficacy is controversial and sublingual immunotherapy with Blomia tropicalis has not yet been studied. This study sought to evaluate the efficacy of sublingual immunotherapy with house dust mite extract in children and adults with house dust mite allergic rhinitis over a period of two years.
METHODS: A prospective observational study was conducted of children and adults diagnosed with house dust mite allergic rhinitis who were treated with sublingual immunotherapy from 2008 to 2012. Total Nasal Symptom Scores, Mini Rhinoconjunctivitis Quality of Life scores and medication usage scores were assessed prospectively.
RESULTS: Thirty-nine patients, comprising 24 children and 15 adults, were studied. Total Nasal Symptom Scores and Mini Rhinoconjunctivitis Quality of Life scores dropped significantly at three months into therapy, and continued to improve. Medication usage scores improved at one year into immunotherapy.
CONCLUSION: Sublingual immunotherapy with house dust mite extracts, including B tropicalis, is efficacious as a treatment for patients with house dust mite allergic rhinitis.
Satisfaction of orthognathic surgical patients in a Malaysian population

Siow KK, Ong ST, Lian CB, Ngeow WC

J Oral Sci, 2002 Dec;44(3-4):165-71.
PMID: 12613507

Thirty-one patients treated at the Faculty of Dentistry, University of Malaya, were assessed for their satisfaction following orthognathic surgery. The female to male ratio was 22:9 with an age range of 17 to 36. Almost all patients (97%) listed appearance as one of their rationales for surgery. More males (78%) than females (59%) wanted functional improvement, while more females (91%) than males (33%) hoped for improvement in self-confidence. All patients reported esthetic improvement while 68% each reported improvement in mastication and self-confidence. Slightly more than half (52%) chose esthetic improvement as the single most important factor resulting in satisfaction. Almost ninety percent of male patients claimed satisfaction with functional improvement, while 68% of those who found satisfaction in improved self-confidence were females. Eighty-seven percent rated their post-surgical changes as being well accepted by their family. The impact of these findings on the success of the surgery and the need to reinforce verbal communication with printed pamphlets are emphasized.
Fulltext Improved Coefficient Recovery and Its Application for Rewritable Data Embedding

Sii A, Ong S, Wong K

J Imaging, 2021 Nov 18;7(11).
PMID: 34821875 DOI: 10.3390/jimaging7110244

JPEG is the most commonly utilized image coding standard for storage and transmission purposes. It achieves a good rate-distortion trade-off, and it has been adopted by many, if not all, handheld devices. However, often information loss occurs due to transmission error or damage to the storage device. To address this problem, various coefficient recovery methods have been proposed in the past, including a divide-and-conquer approach to speed up the recovery process. However, the segmentation technique considered in the existing method operates with the assumption of a bi-modal distribution for the pixel values, but most images do not satisfy this condition. Therefore, in this work, an adaptive method was employed to perform more accurate segmentation, so that the real potential of the previous coefficient recovery methods can be unleashed. In addition, an improved rewritable adaptive data embedding method is also proposed that exploits the recoverability of coefficients. Discrete cosine transformation (DCT) patches and blocks for data hiding are judiciously selected based on the predetermined precision to control the embedding capacity and image distortion. Our results suggest that the adaptive coefficient recovery method is able to improve on the conventional method up to 27% in terms of CPU time, and it also achieved better image quality with most considered images. Furthermore, the proposed rewritable data embedding method is able to embed 20,146 bits into an image of dimensions 512×512.
Bispectral index during modified rapid sequence induction using thiopentone or propofol and rocuronium

Sie MY, Goh PK, Chan L, Ong SY

Anaesth Intensive Care, 2004 Feb;32(1):28-30.
PMID: 15058117

This randomized controlled trial compared Bispectral Index (BIS) values in 40 patients after a modified rapid sequence induction using thiopentone 4 mg/kg or propofol 2 mg/kg with rocuronium 0.6 mg/kg as muscle relaxant. Endotracheal intubation was performed at 60 seconds from induction of anaesthesia and BIS values were recorded for three minutes after induction. At the 120, 150 and 180 second measurements there was a significantly greater proportion of subjects with BIS values < or = 60 ("anaesthetized") in the propofol group compared with the thiopentone group (P values < 0.02, < 0.01 and < 0.01 respectively). All intubations were completed within two minutes. No explicit recall of intubation was detected clinically with either induction agent. The BIS scores we have measured suggest that thiopentone 4 mg/kg is more likely to be associated with lighter planes of anaesthesia and consequent risk of awareness than propofol 2 mg/kg, if intubation is delayed or prolonged.
Adenomatoid odontogenic tumour: a case study with radiographic differential diagnostic considerations

Siar CH, Ong ST, Ng KH

Singapore Dent J, 1996 Jul;21(1):19-22.
PMID: 10597178

Adenomatoid odontogenic tumours (AOT) are benign, hamartomatous odontogenic lesions that not uncommonly mimic a dentigerous cyst radiographically. Such a case as found involving an unerupted left maxillary canine in a 19-year-old Chinese female is described. The differential diagnosis of some common odontogenic cysts and neoplasms occurring in Malaysians, that may present in a dentigerous relationship to an unerupted tooth is discussed. A brief review of the radiographic literature on AOT is also included.
Fulltext Multicentre survey of rheumatoid arthritis patients from ministry of health rheumatology centers in Malaysia

Shahrir M, Shahdan M, Shahid M, Sulaiman W, Mokhtar AM, Othman M, et al.

Int J Rheum Dis, 2008;11(3):287-292.
DOI: 10.1111/j.1756-185X.2008.00379.x

Aim: This is a rheumatoid arthritis (RA) descriptive study, the first of its kind carried out in Malaysia.
Methods: This descriptive study involved 1084 RA patients' epidemiological and clinical data taken from Selayang, Putrajaya, Taiping and Seremban hospitals from June 2004 to December 2005.
Results: One thousand and eighty-four RA patients'data were analysed; 960 (88.6%) patients were female and 124 (11.4%) were male, approximately 8 : 1 M : F ratio. The majority of the patients were Indian (591; 54.5%), followed by the Malays (340; 31.4%), Chinese (126; 11.6%), indigenous (13; 1.2%) and others (14; 1.3%). Mean age was 49.6 ± 11.8 years with the youngest being 15 years and the oldest 88 years of age. Mean age for males was 52.0 ± 12.0 and females 49.3 ± 11.7 years (P =; 0.017). Most of these patients were housewives (565; 52.1%), followed by paid workers (266; 24.5%), retired patients (80; 7.4%), unemployed (76; 7.0%) and others (97; 8.9%). Mean duration of illness was 8.4 ± 6.7 years; 805 (74.3%) patients were relatively new patients (≤ 2 years illness duration) and 279 (25.7%) patients had illness duration > 2 years. Eight hundred and six (74.4%) were seropositive RA patients and 385 (35.5%) had presence of deformity. The majority of patients were treated with methotrexate (178; 16.4%), followed by combination of methotrexate, sulfasalazine and hydroxychloroquine (143; 13.2%), leflunomide (140; 12.9%), sulfasalazine (133; 12.3%) and combination of methotrexate and sulfasalazine (108; 10%).
Conclusion: In the above study, the majority of patients were female (960; 88.6%), Indian (591; 54.5%), had a mean age of 49.6 ± 11.8 years, most were housewives with a mean duration of illness of 8.4 ± 6.7 years and were treated with methotrexate (178; 16.4%). The results of the study may help Malaysian rheumaologists to understand their patients better and treat RA holistically.
Comment in: Yeap SS. Comment on: Multicentre survey of rheumatoid arthritis patients from Ministry of Health rheumatology centres in Malaysia. Int J Rheum Dis. 2009 Jul;12(2):177-8; author reply 179. doi: 10.1111/j.1756-185X.2009.01403.x. PubMed PMID: 20374340.
Fulltext Marked junctional bradycardia, prolonged QT interval and torsade de pointes in acute phenothiazine intoxication in a schizophrenic patient. A case report

Quek DK, Ong SB, Chan PY

Med J Malaysia, 1988 Jun;43(2):173-7.
PMID: 2907093
Fulltext Myocardial infarction, circadian rhythm and delay in hospital admission

Quek DK, Ong SB, Lim LY

Med J Malaysia, 1989 Mar;44(1):14-22.
PMID: 2626108

Circadian variations have been observed in the onset of acute coronary syndromes including acute myocardial infarction. We studied 422 acute myocardial infarction patients who presented to the coronary care unit of General Hospital Kuala Lumpur. Of the 318 (75.4%) patients whose data was complete, a circadian rhythm with bimodal peak was demonstrated. The second quarter of the day i.e. 6.00 a.m. to 12 noon was shown to have a significantly increased frequency of onset of acute myocardial infarction (p less than 0.05). Time delay in presenting to the hospital was also determined. This showed that 56.8% of acute myocardial infarction patients presented early, within four hours of the onset of symptoms. By six hours, more than 71% had sought hospital care. This early presentation to the hospital may offer a realistic opportunity for optimal thrombolytic therapy should this treatment modality be offered as routine to infarct patients.
Fulltext Cigarette smoking and the risk of myocardial infarction, and acute non-infarct coronary events among Malaysian women

Quek DK, Lim LY, Ong SB

Med J Malaysia, 1989 Sep;44(3):210-23.
PMID: 2626136

In a prospective case-control study over a two-year period involving 1006 women, 264 women with acute myocardial infarction (AMI), 305 with non-infarct acute coronary syndromes (CAD) were compared with 437 women with no coronary heart disease (Controls), to determine the relationship between cigarette smoking and other risks factors with coronary heart disease. A history of current cigarette smoking was strongly associated with the risk of coronary events for both AMI And CAD (p less than 0.001). 23.9% of patients with acute coronary syndromes were current smokers, compared with only 12.8% among controls. Overall, women smokers had about a two-fold increase in risk for all coronary events. Younger women smokers (less than 40 years) and those between 61-70 years had particularly higher risks (10.3 and 2.7 times respectively (p less than 0.01, p less than 0.02). A dose-response pattern of increased AMI risks (from 2.0 to 2.9 times) among women smokers was also found, corresponding to the number of cigarettes smoked per day (p less than 0.05). Other significant coronary risk factors established were: postmenopausal status (OR 6.5), diabetes mellitus (OR 5.1), hypertension (OR 1.6), family history of premature coronary heart disease less than 50 years (OR 1.3) and use of oral contraceptive pills (OR 1.4). Our results thus emphasize that cigarette smoking is an important determinant of acute coronary events even among Malaysian women.
Fulltext Association of diabetic autonomic neuropathy with painless myocardial ischaemia induced by exercise

Quek DK, Khor PG, Ong SB

Singapore Med J, 1992 Apr;33(2):177-81.
PMID: 1621124

Silent myocardial ischaemia is now well-recognised in patients with symptomatic coronary artery disease. Its pathogenesis remains speculative, though diminished sensitivity to pain is thought to be one of the mechanisms involved. Because cardiovascular autonomic dysfunction occurs frequently in diabetic patients, we postulate that it contributes towards painless myocardial ischaemia among them. Forty consecutive diabetic (type II) male patients and ten normal volunteers were studied. Using 5 previously-validated noninvasive tests for autonomic dysfunction, 14 of these diabetic men had definite autonomic neuropathy (at least 2 abnormal tests). All 50 subjects were then exercised on a motor-driven treadmill to either exhaustion or chest pains. Thirty-three diabetic subjects were tested positive, with significant (greater than 1 mm) ST segment depression over at least 2 contiguous leads. Of these, 18 were associated with typical angina but the other 15 stopped because of fatigue or exhaustion (ie painless). Thirteen subjects who had definite autonomic neuropathy (AN+) had positive exercise ECG tests-10 had painless ischaemia, and only 3 had angina. This contrasted with 15 patients who had painful ischaemia and 5 who had painless ischaemia among the group without (AN-)autonomic dysfunction (p = 0.0047, Fisher's exact test). There were no significant differences among the various groups for peak rate-pressure-product, all subjects attaining similar maximal oxygen consumption states during which ischaemic ST segment changes were noted (painful AN+: 21917 +/- 4753; painless AN+: 20117 +/- 6752; painful AN-: 16544 +/- 4063; painless AN-: 22220 +/- 4341, p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Fulltext Torsade de pointes and syncopal attacks in a 26-year old woman with congenital complete heart block and prolonged QT interval

Quek DK, Ong SB

Singapore Med J, 1990 Apr;31(2):185-8.
PMID: 2371586

A 26-year old woman with congenital complete heart block and prolonged QT interval presented for the first time with syncopal attacks associated with torsade de pointes in adulthood. Cardioversion followed by overdrive pacing was needed to finally control the unstable rhythm. During episodes of non-capture, paraoxysms of torsade de pointes leading to ventricular flutter were recorded by a 24-hour ambulatory electrocardiographic monitoring. Beta-blockade and permanent ventricular pacing finally abolished both the syncopal attacks and the torsade phenomena. The prognosis of congenital complete heart block associated with QT prolongation resembles that of the Romano-Ward syndrome. Recognition of this variant would facilitate earlier treatment of this rare but potentially lethal disorder.
Fulltext The impact of local surface changes in Borneo on atmospheric composition at wider spatial scales: coastal processes, land-use change and air quality

Pyle JA, Warwick NJ, Harris NR, Abas MR, Archibald AT, Ashfold MJ, et al.

Philos Trans R Soc Lond B Biol Sci, 2011 Nov 27;366(1582):3210-24.
PMID: 22006963 DOI: 10.1098/rstb.2011.0060

We present results from the OP3 campaign in Sabah during 2008 that allow us to study the impact of local emission changes over Borneo on atmospheric composition at the regional and wider scale. OP3 constituent data provide an important constraint on model performance. Treatment of boundary layer processes is highlighted as an important area of model uncertainty. Model studies of land-use change confirm earlier work, indicating that further changes to intensive oil palm agriculture in South East Asia, and the tropics in general, could have important impacts on air quality, with the biggest factor being the concomitant changes in NO(x) emissions. With the model scenarios used here, local increases in ozone of around 50 per cent could occur. We also report measurements of short-lived brominated compounds around Sabah suggesting that oceanic (and, especially, coastal) emission sources dominate locally. The concentration of bromine in short-lived halocarbons measured at the surface during OP3 amounted to about 7 ppt, setting an upper limit on the amount of these species that can reach the lower stratosphere.

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