The N-terminal domains of NLR immune receptors exhibit structural and functional similarities across divergent plant lineages

Nucleotide-binding domain and leucine-rich repeat (NLR) proteins are a prominent class of intracellular immune receptors in plants. However, our understanding of plant NLR structure and function is limited to the evolutionarily young flowering plant clade. Here, we describe an extended spectrum of NLR diversity across divergent plant lineages and demonstrate the structural and functional similarities of N-terminal domains that trigger immune responses. We show that the broadly distributed coiled-coil (CC) and toll/interleukin-1 receptor (TIR) domain families of non-flowering plants retain immune-related functions through trans-lineage activation of cell death in the angiosperm Nicotiana benthamiana. We further examined a CC subfamily specific to non-flowering lineages and uncovered an essential N-terminal MAEPL motif that is functionally comparable to motifs in resistosome-forming CC-NLRs. Consistent with a conserved role in immunity, the ectopic activation of CCMAEPL in the non-flowering liverwort Marchantia polymorpha led to profound growth inhibition, defense gene activation, and signatures of cell death. Moreover, comparative transcriptomic analyses of CCMAEPL activity delineated a common CC-mediated immune program shared across evolutionarily divergent non-flowering and flowering plants. Collectively, our findings highlight the ancestral nature of NLR-mediated immunity during plant evolution that dates its origin to at least ∼500 million years ago.

Effector-mediated relocalization of a maize lipoxygenase protein triggers susceptibility to Ustilago maydis

As the gall-inducing smut fungus Ustilago maydis colonizes maize (Zea mays) plants, it secretes a complex effector blend that suppresses host defense responses, including production of reactive oxygen species (ROS) and redirects host metabolism to facilitate colonization. We show that the U. maydis effector ROS burst interfering protein 1 (Rip1), which is involved in pathogen-associated molecular pattern (PAMP)-triggered suppression of host immunity, is functionally conserved in several other monocot-infecting smut fungi. We also have identified a conserved C-terminal motif essential for Rip1-mediated PAMP-triggered suppression of the ROS burst. The maize susceptibility factor lipoxygenase 3 (Zmlox3) bound by Rip1 was relocalized to the nucleus, leading to partial suppression of the ROS burst. Relocalization was independent of its enzymatic activity, revealing a distinct function for ZmLox3. Most importantly, whereas Zmlox3 maize mutant plants showed increased resistance to U. maydis wild-type strains, rip1 deletion strains infecting the Zmlox3 mutant overcame this effect. This could indicate that Rip1-triggered host resistance depends on ZmLox3 to be suppressed and that lox3 mutation-based resistance of maize to U. maydis requires functional Rip1. Together, our results reveal that Rip1 acts in several cellular compartments to suppress immunity and that targeting of ZmLox3 by Rip1 is responsible for the suppression of Rip1-dependent reduced susceptibility of maize to U. maydis.

TOPLESS promotes plant immunity by repressing auxin signaling and is targeted by the fungal effector Naked1

In plants, the antagonism between growth and defense is hardwired by hormonal signaling. The perception of pathogen-associated molecular patterns (PAMPs) from invading microorganisms inhibits auxin signaling and plant growth. Conversely, pathogens manipulate auxin signaling to promote disease, but how this hormone inhibits immunity is not fully understood. Ustilago maydis is a maize pathogen that induces auxin signaling in its host. We characterized a U. maydis effector protein, Naked1 (Nkd1), that is translocated into the host nucleus. Through its native ethylene-responsive element binding factor-associated amphiphilic repression (EAR) motif, Nkd1 binds to the transcriptional co-repressors TOPLESS/TOPLESS-related (TPL/TPRs) and prevents the recruitment of a transcriptional repressor involved in hormonal signaling, leading to the de-repression of auxin and jasmonate signaling and thereby promoting susceptibility to (hemi)biotrophic pathogens. A moderate upregulation of auxin signaling inhibits the PAMP-triggered reactive oxygen species (ROS) burst, an early defense response. Thus, our findings establish a clear mechanism for auxin-induced pathogen susceptibility. Engineered Nkd1 variants with increased expression or increased EAR-mediated TPL/TPR binding trigger typical salicylic-acid-mediated defense reactions, leading to pathogen resistance. This implies that moderate binding of Nkd1 to TPL is a result of a balancing evolutionary selection process to enable TPL manipulation while avoiding host recognition.

Parental perspectives towards sugar-sweetened beverages and polices: a qualitative study

PURPOSE

This qualitative study aimed to understand parental perception of (1) sugar-sweetened beverages (SSB) and implications of SSB on health; (2) their role in shaping their children's consumption of SSB; (3) the influences on SSB consumption of their children; and (4) potential government policies targeted at controlling SSB consumption.

METHODS

English-speaking parents of pre-schoolers aged 2-6 years were recruited. Semi-structured interviews based on the knowledge, attitude, practice framework were conducted, and transcripts were subjected to thematic analysis based on inductive approaches. Recruitment continued until data saturation was reached.

RESULTS

Twenty parents participated in the study and themes addressing the objectives identified. (1) There were misconceptions regarding the healthfulness of certain non-packaged SSB such as traditional remedies and juices. Some were unaware about the association between SSB and dental caries. (2) The need to reduce and restrict sugar consumption for overall and oral health reasons was well-recognised, but the extent of control varied. (3) Multiple stakeholders including pre-schools, grandparents and domestic helpers were involved in shaping children's diet. Children's sugar intake was also influenced by environmental factors, such as the ubiquitously available SSB, targeted marketing and high cost of healthy alternatives. (4) Participants were less accepting towards SSB taxation than the ban of SSB sales.

CONCLUSION

Despite the awareness of the types of SSBs and the general/oral health implications of sugar consumption, misconceptions exist. Although most parents possessed the knowledge and attitude, this did not translate into the practice of reducing sugar consumption in their children. There was no SSB reduction policy that had overwhelming acceptability.

A cross-kingdom conserved ER-phagy receptor maintains endoplasmic reticulum homeostasis during stress

Eukaryotes have evolved various quality control mechanisms to promote proteostasis in the endoplasmic reticulum (ER). Selective removal of certain ER domains via autophagy (termed as ER-phagy) has emerged as a major quality control mechanism. However, the degree to which ER-phagy is employed by other branches of ER-quality control remains largely elusive. Here, we identify a cytosolic protein, C53, that is specifically recruited to autophagosomes during ER-stress, in both plant and mammalian cells. C53 interacts with ATG8 via a distinct binding epitope, featuring a shuffled ATG8 interacting motif (sAIM). C53 senses proteotoxic stress in the ER lumen by forming a tripartite receptor complex with the ER-associated ufmylation ligase UFL1 and its membrane adaptor DDRGK1. The C53/UFL1/DDRGK1 receptor complex is activated by stalled ribosomes and induces the degradation of internal or passenger proteins in the ER. Consistently, the C53 receptor complex and ufmylation mutants are highly susceptible to ER stress. Thus, C53 forms an ancient quality control pathway that bridges selective autophagy with ribosome-associated quality control in the ER.

The Long-Term Impact of Functional Disability on Hospitalization Spending in Singapore

Singapore is one of the fastest-aging populations due to increased life expectancy and lowered fertility. Lifestyle changes increase the burden of chronic diseases and disability. These have important implications for social protection systems. The goal of this paper is to model future functional disability and healthcare expenditures based on current trends. To project the health, disability and hospitalization spending of future elders, we adapted the Future Elderly Model (FEM) to Singapore. The FEM is a dynamic Markov microsimulation model developed in the US. Our main source of population data was the Singapore Chinese Health Study (SCHS) consisting of 63,000 respondents followed up over three waves from 1993 to 2010. The FEM model enables us to investigate the effects of disability compounded over the lifecycle and hospitalization spending, while adjusting for competing risk of multi-comorbidities. Results indicate that by 2050, 1 in 6 elders in Singapore will have at least one ADL disability and 1 in 3 elders will have at least one IADL disability, an increase from 1 in 12 elders and 1 in 5 elders respectively in 2014. The highest prevalence of functional disability will be in those aged 85 years and above. Lifetime hospitalization spending of elders aged 55 and above is US$24,400 (30.2%) higher among people with functional disability compared to those without disability. Policies that successfully tackle diabetes and promote healthy living may reduce or delay the onset of disability, leading to potential saving. In addition, further technological improvements may reduce the financial burden of disability.

Ethnic disparities in risk of cardiovascular disease, end-stage renal disease and all-cause mortality: a prospective study among Asian people with Type 2 diabetes

AIM

To study prospectively the ethnic-specific risks of cardiovascular disease, end-stage renal disease and all-cause mortality in patients with Type 2 diabetes mellitus among native Asian subpopulations.

METHODS

A total of 2337 subjects with Type 2 diabetes (70% Chinese, 17% Malay and 13% Asian Indian) were followed for a median of 4.0 years. Time-to-event analysis was used to study the association of ethnicity with adverse outcomes.

RESULTS

Age- and gender-adjusted hazard ratios for cardiovascular disease in ethnic Malay and Asian Indian subjects were 2.01 (1.40-2.88; P<0.0001) and 1.60 (1.07-2.41; P=0.022) as compared with Chinese subjects. Adjustment for conventional cardiovascular disease risk factors, including HbA1c , blood pressure and lipid profile, slightly attenuated the hazards in Malay (1.82, 1.23-2.71; P=0.003) and Asian Indian subjects (1.47, 0.95-2.30; P=0.086); However, further adjustment for baseline renal function (estimated GFR) and albuminuria weakened the cardiovascular disease risks in Malay (1.48, 0.98-2.26; P=0.065) but strengthened that in Asian Indian subjects (1.81, 1.14-2.87; P=0.012). Competing-risk regression showed that the age- and gender-adjusted sub-distribution hazard ratio for end-stage renal disease was 1.87 (1.27-2.73; P=0.001) in Malay and 0.39 (0.18-0.83; P=0.015) in Asian Indian subjects. Notably, the difference in end-stage renal disease risk among the three ethnic groups was abolished after further adjustment for baseline estimated GFR and albuminuria. There was no significant difference in risk of all-cause mortality among the three ethnic groups.

CONCLUSIONS

Risks of cardiovascular and end-stage renal diseases in native Asian subjects with Type 2 diabetes vary substantially among different ethnic groups. Differences in prevalence of diabetic kidney disease may partially explain the ethnic disparities.

Health-related quality of life of Asian patients with end-stage renal disease (ESRD) in Singapore

BACKGROUND

This study aimed to identify factors associated with the health-related quality of life (HRQOL) of multiethnic Asian end-stage renal disease (ESRD) patients treated with dialysis. The role of dialysis modality was also explored.

METHODS

Data used in this study were from two cross-sectional surveys of Singaporean ESRD patients on haemodialysis (HD) or peritoneal dialysis (PD). In both surveys, participants were assessed using the kidney disease quality of life (KDQOL) instrument and questions assessing socio-demographic characteristics. Clinical data including co-morbidity (measured by Charlson comorbidity index [CCI]), albumin level, haemoglobin level, and dialysis-related variables (e.g. dialysis vintage and dialysis adequacy) were retrieved from medical records. The 36-item KDQOL (KDQOL-36) was used to generate three summary scores (physical component summary [PCS], mental component summary [MCS] and kidney disease component summary [KDCS]) and two health utility scores (Short Form 6-dimension [SF-6D] and EuroQol 5-dimension [EQ-5D]). Linear regression analysis was performed to examine the association of factors with each of the HRQOL scale scores.

RESULTS

Five hundred and two patients were included in the study (mean age 57.1 years; male 52.4 %; HD 236, PD 266). Mean [standard deviation (SD)] PCS, MCS and KDCS scores were 37.9 (9.7), 46.4 (10.8) and 57.6 (18.1), respectively. Mean (SD) health utility score was 0.66 (0.12) for SF-6D and 0.60 (0.21) for EQ-5D. In multivariate regression analysis, factors found to be significantly associated with better HRQOL included: young (<45 years) or old age (>60 years), low CCI (<5), high albumin (≥37 g/l) and high haemoglobin (≥11 g/dl) with PCS; long dialysis vintage (≥3.5 years) with MCS; old age, Malay ethnicity and PD modality with KDCS; low CCI, high albumin and high haemoglobin with EQ-5D and high albumin with SF-6D.

CONCLUSIONS

Clinical characteristics are better predictors of HRQOL in ESRD patients than socio-demographics in Singapore. Dialysis modality has no impact on the health utility of those patients.

Mammographic density and its interaction with other breast cancer risk factors in an Asian population

BACKGROUND

Joint effects of mammographic density and other risk factors on breast cancer risk remain unclear.

METHODS

From The Singapore Breast Screening Project, we selected 491 cases and 982 controls. Mammographic density was measured quantitatively. Data analysis was by conditional logistic regression.

RESULTS

Density was a significant risk factor, adjusting for other factors. Density of 76-100% had an odds ratio of 5.54 (95% CI 2.38-12.90) compared with 0-10%. Density had significant interactions with body mass index and oral contraceptive use (P=0.02).

CONCLUSIONS

Percent density increases breast cancer risk in addition to effects of other risk factors, and modifies the effects of BMI and OCs.

Cancer survival in Singapore, 1993-1997

The Singapore cancer registry is a national registry established in 1968. Cancer registration is done by passive methods. The registry contributed survival data on 45 cancer sites or types registered during 1993-1997. Data on 34 cancers registered during 1968-1997 were utilized for survival trend by period and cohort approaches. Follow-up was done by passive methods, with median follow-up ranging between 2-72 months for different cancers. The proportion with histologically verified diagnosis for various cancers ranged between 27-100%; death certificates only (DCOs) comprised 0-7%; 76-100% of total registered cases were included for the survival analysis. The top-ranking cancers on 5-year age-standardized relative survival rates were nonmelanoma skin (96%), thyroid (90%), testis (88%), corpus uteri (77%), breast (74%), Hodgkin lymphoma (73%) and penis (70%). Five-year relative survival by age group showed either a decreasing trend with increasing age groups or was fluctuating. Localized stage of disease ranged between 18-65% for various cancers and survival decreased with increasing extent of disease. Period survival closely predicted survival experience of cancers diagnosed in that period, and an increasing trend in period survival over different periods indicated an improved prognosis for cancers diagnosed in those calendar periods.

Abstract P3-11-08: Incidence and Outcome of Male and Female Breast Cancer: A Multinational Population Based Study

Background: Male breast cancer is a rare disease as its incidence rate is about 0.5% to 1% of that of female breast cancer. Given its scarcity, few studies have assessed the risk and prognosis.

Methods: We performed a multi-national population based study of 569,771 female breast cancer patients and 3,615 male breast cancer patients diagnosed in Denmark, Finland, Switzerland, Norway, Singapore and Sweden from 1943 to 2007. We calculated incidence and mortality as well as overall survival for both sexes. Life table analysis and Cox proportional hazard model were used to analyze the survival.

Results: The overall incidence rates, adjusted to the World Standard Population, of breast cancer were 60.2 per 100,000 in women and 0.4 per 100,000 in men. Women were diagnosed with breast cancer at a younger median age (61.4 years) than men (68.9 years). Among the 203,093 patients (35%) with information on TNM stage, 50% of the women and 47% of men were classified as stage I whilst stage III and stage IV cases accounted for 11% and 20% for women and men respectively. The 5-year cumulative survival was 66.2% for women and 53.0% for men. The adjusted relative risk of death was 24% higher in men [HR 1.24 (95% CI, 1.19-1.28)] as compared to women after controlling for age and time at diagnosis. Men had an 18% higher relative risk of death [HR 1.18 (95% CI, 1.09-1.27)] compared to women after further adjustment for TNM stage. Conclusion: Male breast cancer patients have later onset and worse prognosis than female patients. This may be due to the difference in tumour characteristics and treatment.

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P3-11-08.

Global health: challenges and opportunities for Singapore

Over the past decade, global health has evolved from a buzzword to a discipline, attracting interest from governments, academic institutions and funding organisations. Global health centres, institutes and initiatives in Western countries have increased in both size and number, aided primarily by institutional backing and supportive funding mechanisms. As the rise to prominence of global health on the public health agenda also coincides with shifts in global balances of power, Asia, as well as Singapore, has an expanded role to play in supporting global health teaching and research, both in the region and throughout the world. Foundations, universities, government agencies, statutory boards and the private sector all have an important role to play in moving the global health agenda forward in Singapore. Rigorous global health training and increased funding for global health research are now timely and essential in order for global health, as a discipline, to develop within Singapore and have an impact within the region.

Effect of childbirth after treatment on long-term survival from breast cancer

Background

This study quantified long-term absolute and relative mortality risks of survivors of breast cancer with subsequent childbirth.

Methods

The Singapore Birth Register (n = 319 437), Swedish Multi-Generation Register (n = 11 million) and population-based cancer registries were linked to identify 492 women with childbirth after breast cancer. For these women, cumulative mortality risks and standardized mortality ratios (SMRs) were calculated and compared with those of 8529 women aged less than 40 years with breast cancer without subsequent childbirth, and with those predicted by Adjuvant! Online.

Results

Women with subsequent childbirth had a lower 15-year cumulative overall mortality rate than other women with breast cancer (16·8 (95 per cent confidence interval (c.i.) 13·3 to 20·9) versus 40·7 (39·5 to 41·9) per cent), but a higher relative mortality risk than the background population (SMR 13·6, 95 per cent c.i. 10·6 to 17·3). Mortality risks decreased significantly with increasing interval between diagnosis and subsequent childbirth. Mean 10-year cumulative mortality risks of women with subsequent childbirth were within the range of 10-year mortality predicted by Adjuvant! Online for women with T1 N0 tumours in otherwise perfect health.

Conclusion

This study reinforced the view that pregnancy after breast cancer is not detrimental to survival. However, women who gave birth after this diagnosis had substantially higher mortality risks than young women in the general population. This information may be a valuable addition to routine mortality estimates.

Microarray analysis of multiple candidate genes and associated plasma proteins for nephropathy secondary to type 2 diabetes among Chinese individuals

AIMS/HYPOTHESIS

Evolving research suggests that common and rare alleles jointly constitute the genetic landscape of complex disease. We studied the association between 43 pathway-related candidate genes with 'intermediate phenotype' (i.e. corresponding plasma protein) and diabetic nephropathy in a customised microarray of 1,536 SNPs.

METHODS

In this case-control study of type 2 diabetic Chinese individuals with and without diabetic nephropathy, cases (n = 545) were defined on the basis of a spot urinary albumin/creatinine ratio (ACR) > 113 mg/mmol; the value for controls (n = 503) was ACR < 3.3 mg/mmol. Genotyping was performed using Illumina GoldenGate assay.

RESULTS

No single nucleotide polymorphism (SNP) remained significant in single locus analysis after correction for multiple testing. Therefore, we explored the best approximately 1% SNPs. Of these 13 SNPs, four clustered to a 5' end NADPH oxidase homologue 4 (NOX4) haplotype (GGCC frequency = 0.776) with estimated OR for diabetic nephropathy of 2.05 (95% CI 1.04-4.06) (heterozygous) and 2.48 (1.27-4.83) (homozygous) (p = 0.0055). The haplotype was correlated with plasma Cu/Zn superoxide dismutase (SOD) concentration, suggesting increased oxidative burden. Endothelin-1 SNP (rs1476046G>A, frequency = 0.252) was correlated with plasma C-terminal pro-endothelin-1 concentrations with an estimated OR for diabetic nephropathy of (heterozygous) 1.26 (0.96-1.66) and (homozygous) 1.87 (1.13-3.12) (p = 0.0072). Nitric oxide synthase 1 (NOS1) 5' haplotype (TGTC frequency = 0.38) also revealed a suggestive association with diabetic nephropathy: heterozygous 1.26 (0.95-1.67), homozygous 1.57 (1.04-2.35) (p = 0.0073). A rare NADPH oxidase homologue 1 (NOX1)-coding non-synonymous SNP (Arg315His, frequency = 0.006) was found exclusively among cases.

CONCLUSIONS/INTERPRETATION

Our preliminary observations suggest that common haplotypes from NOX4 and endothelin-1 SNP correlated with plasma Cu/Zn SOD and C-terminal pro-endothelin-1 concentrations, respectively, and might have conferred diabetic nephropathy susceptibility. Common NOS1 and rare NOX1 variants also revealed a suggestive association with diabetic nephropathy. Future studies to validate our observation are needed.

Ethnicity modifies the association between diabetes mellitus and ischaemic heart disease in Chinese, Malays and Asian Indians living in Singapore

AIMS/HYPOTHESIS

The aim of the study was to determine whether the risk of ischaemic heart disease (IHD) associated with diabetes mellitus differs between ethnic groups.

METHODS

Registry linkage was used to identify IHD events in 5707 Chinese, Malay and Asian Indian participants from three cross-sectional studies conducted in Singapore between the years 1984 and 1995. The study provided a median of 10.2 years of follow-up with 240 IHD events experienced. We assessed the interaction between diabetes mellitus and ethnicity in relation to the risk of IHD events using Cox proportional hazards regression.

RESULTS

Diabetes mellitus was more common in Asian Indians. Furthermore, diabetes mellitus was associated with a greater risk of IHD in Asian Indians. The hazard ratio when comparing diabetes mellitus with non-diabetes mellitus was 6.41 (95% CI 5.77-7.12) in Asian Indians and 3.07 (95% CI 1.86-5.06) in Chinese (p = 0.009 for interaction). Differences in the levels of established IHD risk factors among diabetics from the three ethnic groups did not appear to explain the differences in IHD risk.

CONCLUSIONS/INTERPRETATION

Asian Indians are more susceptible to the development of diabetes mellitus than Chinese and Malays. When Asian Indians do develop diabetes mellitus, the risk of IHD is higher than for Chinese and Malays. Consequently, the prevention of diabetes mellitus amongst this ethnic group is particularly important for the prevention of IHD in Asia, especially given the size of the population at risk. Elucidation of the reasons for these ethnic differences may help us understand the pathogenesis of IHD in those with diabetes mellitus.

Angiotensin-I converting enzyme insertion/deletion polymorphism and its association with diabetic nephropathy: a meta-analysis of studies reported between 1994 and 2004 and comprising 14,727 subjects

AIMS/HYPOTHESIS

The ACE insertion/deletion polymorphism has been examined for association with diabetic nephropathy over the past decade with conflicting results. To clarify this situation, we conducted a comprehensive meta-analysis encompassing all relevant studies that were published between 1994 and 2004 and investigated this potential genetic association.

METHODS

A total of 14,727 subjects from 47 studies was included in this meta-analysis. Cases (n=8,663) were type 1 or 2 diabetic subjects with incipient (microalbuminuria) or advanced diabetic nephropathy (proteinuria, chronic renal failure, end-stage renal disease). Control subjects (n=6,064) were predominantly normoalbuminuric.

RESULTS

No obvious publication bias was detected. Using a minimal-case definition based on incipient diabetic nephropathy, subjects with the II genotype had a 22% lower risk of diabetic nephropathy than carriers of the D allele (pooled odds ratio [OR]=0.78, 95% CI=0.69-0.88). While there was a reduced risk of diabetic nephropathy associated with the II genotype among Caucasians with either type 1 or type 2 diabetes, the association was most marked among type 2 diabetic Asians (Chinese, Japanese, Koreans) (OR=0.65, 95% CI=0. 51-0.83). This OR is significantly different from the OR of 0.90 (95% CI= 0.78-1.04) that was obtained for type 2 diabetic Caucasians (p=0.019). Using a stricter case definition based on advanced diabetic nephropathy, a comparable risk reduction of 24-32% was observed among the three subgroups, although statistical significance was reached only among Asians.

CONCLUSIONS/INTERPRETATION

The results of our meta-analysis support a genetic association of the ACE Ins/Del polymorphism with diabetic nephropathy. These findings may have implications for the management of diabetic nephropathy using ACE inhibitors especially among type 2 diabetic Asians.

Role of urinary screening programmes in children in the prevention of chronic kidney disease

INTRODUCTION

This article reviews published literature on the usefulness of population-based urinary screening in the Asian paediatric population.

METHODS

Articles were found in the Medline database using the key words "paediatrics", "urine screening", "proteinuria", "haematuria" and "population". The Asian countries which had carried out population-based urinary screening of the paediatric population included Taiwan, Japan and Korea. One study was found on urinary screening in a select population in Malaysia. Preliminary results of the urinary screening of school children in Singapore are presented and compared with the results found in the above-mentioned countries.

RESULTS

Overall, the proportion of children found to have urinary abnormalities ranged from less than 0.1% of the population screened to almost 50% of a select cohort referred from the screening programmes for the evaluation of urinary abnormalities. In the pilot Singapore school screening programme, the prevalence of clinically significant proteinuria was 1.25 per 1000 children screened. Multivariate analysis showed that low body weight was associated with a 1.8-fold greater risk for proteinuria. The major cause of haematuria and proteinuria in those studies where renal biopsies were performed was glomerulonephritis. The Taiwanese experience also showed a reduction in the incidence of end-stage renal failure diagnosed in children after the onset of urine screening.

CONCLUSION

These studies showed that urinary screening programmes in school children allow the early detection of disease. The cost-benefit ratio for specific populations should be determined before the implementation of such programmes.

Willingness to donate blood samples for genetic research: a survey from a community in Singapore

Studies on the public's willingness to donate blood specimens for genetic research are few and are conducted mainly among Western countries. Little is known about the Asian community's willingness to participate in genetic research. A community-based survey was conducted on 548 adult Singaporeans to examine their willingness to donate blood samples for genetic research and its associated factors. The response rate was 70.3%. About 49.3% (95% CI, 45.1-53.5%) were willing to donate blood for genetic research. In the multivariable Cox regression analysis, willingness was significantly associated with belief in the benefits of genetic research; intention to participate in government studies; having no fear of pain, blood, injections, and needles; and non-concern about the loss of confidentiality. Reasons against donating blood were fear of pain, blood, injections, and needles (38.1%); no self-benefits (24.8%); fear of finding out about having a disease (22.3%); fear of discrimination (18.7%); and concerns about weakness (15.1%) and weight gain (9.4%). Public education programs to promote participation in genetic research should stress its benefits and address people's fears and concerns.

Ethnic variations in female vulnerability after an acute coronary event

OBJECTIVE

To determine the ethnic variation of short and long term female vulnerability after an acute coronary event in a population of Chinese, Indians, and Malays.

DESIGN

Population based registry.

PATIENTS

Residents of Singapore between the ages of 20-64 years with coronary events. Case identification and classification procedures were modified from the MONICA (monitoring trends and determinants in cardiovascular disease) project.

MAIN OUTCOME MEASURES

Adjusted 28 day case fatality and long term mortality.

RESULTS

From 1991 to 1999, there were 16 320 acute coronary events, including 3497 women. Age adjusted 28 day case fatality was greater in women (51.5% v 38.6%, p < 0.001), with a larger sex difference evident among younger Malay patients. This inequality between the sexes was observed in both the pre-hospitalisation and post-admission periods. Among hospitalised patients, women were older, were less likely to have suffered from a previous Q wave or anterior wall myocardial infarction, and had lower peak creatine kinase concentrations. Case fatality was higher among women, with adjusted hazard ratios of 1.64 (95% confidence interval (CI) 1.43 to 1.88) and 1.50 (95% CI 1.37 to 1.64) for 28 day and mean four year follow up periods. There were significant interactions of sex and age with ethnic group (p = 0.017). The adjusted hazards for mortality among Chinese, Indian, and Malay women versus men were 1.30, 1.71, and 1.96, respectively. The excess mortality among women diminished with age.

CONCLUSION

In this multiethnic population, both pre-hospitalisation and post-admission case fatality rates were substantially higher among women. The sex discrepancy in long term mortality was greatest among Malays and in the younger age groups.

The lipoprotein lipase S447X polymorphism and plasma lipids

We studied 4,058 subjects from a representative sample of the Singapore population 1) to determine the association between the S447X polymorphism at the LPL locus and serum lipid concentration in Chinese, Malays, and Asian Indians living in Singapore and 2) to explore any interactions with apolipoprotein E (APOE) genotype, exercise, obesity, cigarette smoking, and alcohol intake. Information on obesity, lifestyle factors (including smoking, alcohol consumption, and exercise frequency), glucose tolerance, and fasting lipids was obtained. Male and female carriers of the X447 allele had lower serum triglyceride concentrations and higher HDL cholesterol (HDL-C) concentrations. The association between the X447 allele and serum HDL-C concentration was modulated by APOE genotype in males and cigarette smoking and alcohol intake in females. The effect of the X447 allele was greatest in men who carried the E4 allele and women who smoked or consumed alcohol. The X447 allele at the LPL locus is common and associated with a less atherogenic lipid profile in Asian populations. Interactions with APOE genotype, cigarette smoking, and alcohol intake reinforce the importance of examining genetic associations, such as this one, in the context of the population of interest.

Ethnic differences among Chinese, Malay and Indian patients with type 2 diabetes mellitus in Singapore

INTRODUCTION

Ethnic differences exist in patients with diabetes mellitus. Not much is known about such differences in Asian populations. The aim of the study was to determine ethnic differences among Chinese, Malay and Indian patients with type 2 diabetes mellitus in Singapore.

METHODS

The study design was cross-sectional, involving 967 patients who were attending follow-up care for type 2 diabetes mellitus at a primary care clinic. Data collection was by patient interview, examination, and from case records. Blood and urine samples were collected for analysis of indicators of diabetic control and albuminuria.

RESULTS

Malays had the highest mean body mass index (BMI) after controlling for age, gender, duration of diabetes and exercise status. Adjusted mean BMI for Malays was 27.4kg per square metres, Indians 25.7kg per square metres, Chinese 24.9kg per square metres, with the p value being less than 0.01. HbA1c levels were highest among Indians after controlling for age, duration of diabetes, body mass index and treatment. Adjusted mean HbA1c for Indians was 8.3 percent, Malays 8.0 percent, and Chinese 7.7 percent, with the p value being less than 0.01. Compared with Chinese, Indians were more likely to have a positive family history of diabetes (prevalence rate ratio (PRR) of 1.3, 95 percent confidence interval (CI) of 1.0 to 1.7), but were less likely to have associated hypertension (PRR of 0.7, 95 percent CI of 0.5 to 1.0) and microalbuminuria and macroalbuminuria (PRR of 0.6, 95 percent CI of 0.4 to 1.0).

CONCLUSION

Ethnic differences exist with regard to BMI, diabetic control as reflected by HbA1c levels, family history of diabetes, presence of associated hypertension, and severity of albuminuria. Indians, while having poorer control of diabetes, are less prone to hypertension and renal complications than Chinese.

Twin births in Singapore: a population-based study using the National Birth Registry

INTRODUCTION

Twin studies are a most effective method to analyse gene and environment interactions. Using data from the Singapore National Registry of Births and Deaths (SNRBD), this paper describes the number of twin and multiple births among different ethnic populations in Singapore.

MATERIALS AND METHODS

All births recorded in the SNRBD from 1 January 1986 to 31 December 2001 were analysed. Outcomes measured were twin and triple birth rates (per 1000 maternities) of the 3 main ethnic groups in Singapore (Chinese, Malays and Asian Indians). Further outcomes were calculated using Weinberg's differential rule to estimate the number of monozygotic and dizygotic twins.

RESULTS

Overall twin birth rates have steadily increased across all ethnic groups (7 to 9/1000). The largest increase in multiple births among the ethnic groups were twins born to Asian Indian fathers (6.9 to 9.9/1000) and Malay mothers (5.9 to 9.8/1000). A significant difference in birth rates between the ethnic groups was found during the years 1994 to 1997, where Chinese parents had the lowest multiple birth rates and Asian Indians the highest. Estimation and ratios of monozygotic and dizygotic twin births differed among the ethnic groups: Asian Indians had the highest ratios, followed by the Chinese and, lastly, the Malays.

CONCLUSION

The SNRBD has provided an overview of multiple births in Singapore, although the establishment of a national twin register would enable more detailed analysis of genetic and environmental effects in multiple births.

Low birth weight in relation to parental occupations—a population-based registry in Singapore (1994–1998)

OBJECTIVES

To study the association between parental occupation and low birth weight (LBW) in infants born in Singapore between 1994 and 1998. Other factors that may be related to LBW were also investigated.

METHODS

A retrospective study. Information was obtained from the Singapore National Registry of Births and Deaths on parental occupations for live births between 1 January 1994 to 31 December 1998. Parental date of birth, ethnic group, and highest educational qualification were also obtained. The associations between these factors and the occurrence of LBW was assessed using descriptive statistics and logistic regression analysis.

RESULTS

A total 208,360 live births were studied. Analyses were restricted to singleton births > or =37th week gestation (total of 189,064). No significant differences in LBW risk were found for the different maternal occupational groups, compared with a referent group ("legislators, senior officers, and managers"). However, fathers who were "not working" (OR=2.04; 1.57-2.65), "not classifiable by occupation" (OR=1.34; 1.09-1.65), and "cleaners, laborers, and related workers" (OR=1.32; 1.12-1.55) had the highest risk of LBW infants when compared with "legislators, senior officers, and managers," after adjustment for maternal occupation, ethnic group, educational level and age, paternal educational level, infant gestational age, sex, and birth order.

CONCLUSION

Certain paternal occupational groups appear to be associated with a higher risk of having LBW infants. This may be linked to socioeconomic status and possible work-related factors. Future studies of pregnancy outcomes should not ignore the potential contributions of fathers.

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

BACKGROUND

Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.

METHODS

This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.

RESULTS

Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.

CONCLUSION

Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

Basal cell carcinoma, squamous cell carcinoma and melanoma of the skin: analysis of the Singapore Cancer Registry data 1968-97

BACKGROUND

There has been an alarming recent increase in skin cancer incidence among fair-skinned populations. Information from Asian populations is less readily available.

OBJECTIVES

This study examines time trends and ethnic differences of skin cancers among Asians in Singapore.

METHODS

Data from 1968 to 1997 was obtained from the Singapore Cancer Registry, a population-based registry. Age-standardized incidence rates (ASRs) and age-adjusted average annual percentage change, using the Poisson regression model, were calculated.

RESULTS

A total of 2650 basal cell carcinomas (BCCs), 1407 squamous cell carcinomas (SCCs) and 281 melanomas were reported. There was an overall increase of skin cancer from 6.0 per 100000 person years (1968-72) to 8.9 per 100000 person years (1993-97). BCC incidence increased 3% annually, melanoma remained constant, and SCC decreased 0.9% annually. BCC ASRs were highest among Chinese, then Malays and Indians. A similar pattern was noted for SCC and melanomas.

CONCLUSIONS

The incidence rates of skin cancer increased in Singapore during the period 1968-97. Fairer-skinned Chinese had a higher incidence of skin cancer.

Angular regression and the detection of the seasonal onset of disease

BACKGROUND

In examining the seasonality of onset of a disease over the year, investigators attempt to identify the peak of onset, and its magnitude. A second objective is to see if the day in which the disease manifests itself is related to subject-specific characteristics or environmental factors.

METHOD

This paper describes appropriate statistical methodology for the situation where seasonality can be summarised by either a single peak or several peaks, possibly determined by patient characteristics or external influences. The circular, rather than linear, nature of the day of onset of a disease (irrespective of year) requires angular regression techniques to assess these relations, and the von Mises distribution replaces the normal distribution in this context.

RESULTS

The methods outlined are illustrated by a national study of those experiencing an attack of acute primary angle-closure glaucoma in Singapore.

CONCLUSIONS

We recommend re-analyses of already published work on seasonality of disease using this angular methodology. We anticipate that this may provide both useful further insight into aspects of aetiology and case studies for the methods themselves.

Cancer incidence in Singapore, 1998 to 1999

The age-standardised incidence rates for all cancers for 1998-1999 were 235.0 per 100,000 in males and 199.8 per 100,000 in females. The corresponding rates for 1993-1997 were 233.1 per 100,000 in males and 198.1 per 100,000 in females. The greatest difference was for breast cancer in females with age-standardised incidence rates increasing from 46.1 to 53.1 cases per 100,000 persons per year between these time periods. There also appears to be a shift of the peak age-specific incidence for breast cancer from premenopausal to postmenopausal years over this period. This suggests that our breast cancer incidence pattern is rapidly becoming more similar to populations in the West.

Risk factors and incident coronary heart disease in Chinese, Malay and Asian Indian males: the Singapore Cardiovascular Cohort Study

OBJECTIVE

This prospective study in Singapore investigated the relationships of established coronary risk factors with incident coronary heart disease (CHD) for Chinese, Malay, and Asian Indian males.

SUBJECTS

A cohort (consisting of 2879 males without diagnosed CHD) derived from three previous cross-sectional surveys.

METHODS

Individual baseline data were linked to registry databases to obtain the first event of CHD. Hazard ratios (HR) or relative risks for risk factors were calculated using Cox's proportional hazards model with adjustment for age and ethnic group and adjustment for age, ethnic group and all other risk factors (overall adjusted).

RESULTS

There were 24,986 person-years of follow-up. The overall adjusted HR with 95% CI are presented here. Asian Indians were at greatest risk of CHD, compared to Chinese (3.0; 2.0-4.8) and Malays (3.4; 1.9-3.3). Individuals with hypertension (2.4; 1.6-2.7) or diabetes (1.7; 1.1-2.7) showed a higher risk of CHD. High low density lipoprotein cholesterol (LDL-C) (1.5; 1.0-2.1), high fasting triglyceride (1.5; 0.9-2.6) and low high density lipoprotein cholesterol (HDL-C) (1.3; 0.9-2.0) showed a lesser but still increased risk. Alcohol intake was protective with non-drinkers having an increased risk of CHD (1.8; 1.0-3.3). Obesity (body mass index > or =30) showed an increased risk (1.8; 0.6-5.4). An increased risk of CHD was found in cigarette smokers of > or =20 pack years (1.5; 0.9-2.5) but not with lesser amounts.

CONCLUSIONS

The increased susceptibility of Asian Indian males to CHD has been confirmed in a longitudinal study. All of the examined established risk factors for CHD were found to play important but varying roles in the ethnic groups in Singapore.

Population-based cancer survival in Singapore, 1968 to 1992: an overview

The Singapore Cancer Registry has provided comprehensive population-based incidence data since 1968. This paper describes the population-based survival analysis of the registry data. All invasive primary cancers diagnosed from January 1, 1968 to December 31, 1992 were passively followed up until December 31, 1997. Only 5.8% were lost to follow-up. Cumulative and observed survival rates were calculated using Hakulinen's method. Overall 5-year relative survival rates have increased dramatically over the 25-year period in both genders. Significant increases are seen with nasopharynx, stomach and colo-rectum cancers, non-Hodgkin's lymphoma, leukemias and cancers of the testis, cervix, ovaries and breast. When compared with the Surveillance, Epidemiology and End Results (SEER) rates in the United States, the 5-year relative survival rates in Singapore are generally lower. However, the rate of change between the two countries is fairly similar. On the average, the rates are 10 to 15 years behind the SEER rates and 5 to 10 years behind Finland, Switzerland and Japan, but they are close to the UK rates. The age-standardized 5-year survival rate for Singapore is higher for most sites compared with other developing countries like Qidong (China), Madras (India), Bombay (India) and Chiang Mai (Thailand). The 25-year trend in cancer survival in Singapore showed two extreme groups: those showing no change and those showing significant improvements. Reducing the incidence of cancers belonging to the first group remains the only viable mode of cancer control. For cancers in the second group, improvement in survival is due to a combination of successful early detection measures and effective treatment services in Singapore.

Academic achievement, close up work parameters, and myopia in Singapore military conscripts

AIM

To determine the relation of refractive error to environmental factors, including close up work, in Singapore military conscripts.

METHODS

A cross sectional study was conducted on 429 Singapore military conscripts. Non-cycloplegic refraction and A-scan biometry were performed in both eyes. A detailed questionnaire was administered by in-person interview to obtain information about current and past near work activity, extra tuition lessons, educational experiences, and family demographics.

RESULTS

Myopia associated with the conscript having been educated in the (gifted, special, or express) educational streams (adjusted odds ratio (OR) = 3.8, 95% confidence interval CI 2.0-7.3), and having completed pre-university education (OR=4.1, 95% CI 1.9-8.8). The reported close up work activity at age 7 years did correlate with age of onset of myopia (p<0.001). In parallel, supplemental tuition lessons in primary school has (OR=2.6, 95% CI 1.4-4.9) associated with conscript myopia. Parental myopia was positively associated with myopia (p<0.001), but this relation disappeared when adjusted for environmental factors. Current (p=0.83) and past close up work activity at age 7 years (p=0.13) did not correlate with myopia.

CONCLUSION

Educational level and educational stream positively related to myopia. A relation was observed with reported close up work activity in early childhood and with tuition classes during elementary school, but not with current close up work activity. These results underscore the strong influence of environment in myopia pathogenesis but a role for close up work activity remains indeterminate.

Does education explain ethnic differences in myopia prevalence? A population-based study of young adult males in Singapore

PURPOSE

To study interethnic variation in myopia prevalence and severity in young adult males in Singapore and to determine whether these variations are related to differences in education level.

METHODS

A population-based survey of refractive errors in a cohort of 15,095 military conscripts between July 1996 and June 1997 using noncycloplegic autorefraction and a standard questionnaire. Prevalence rates of myopia (<-0.5 D) and severe myopia (<-6.0 D) were determined for Chinese, Malay, and Indian men; prevalence rate ratios were compared after adjusting for education level.

RESULTS

Singapore has one of the highest prevalences of myopia (79.3%) and severe myopia (13.1%), with Chinese having higher rates (82.2%, 95% confidence interval 81.5, 82.9) compared with Indians (68.7%, 95% confidence interval 65.1, 67.1) and Malays (65.0%, 95% confidence interval 62.9, 67.1). Education was strongly associated with prevalence and severity of myopia. However, significant interethnic variation persisted after adjusting for education.

CONCLUSIONS

There is a high prevalence of myopia in Singapore. Although prevalence and severity of myopia were strongly associated with education, interethnic variation observed was not fully explained by differences in education level.

Myopia and night lighting in children in Singapore

AIM

To examine the role of night time lighting and myopia in children in Singapore

METHODS

A cross sectional study was conducted on 1001 children in two Singapore schools. Cycloplegic refraction and A-scan biometry measurements were made in both eyes. A detailed questionnaire was completed by the parents to obtain information on night time lighting, near work activity, educational and demographic factors.

RESULTS

There was no difference in myopia prevalence rates in children exposed to night time light (33.1%) compared with children who slept in the dark (31.4%) before age 2. In addition, vitreous chamber depth was not related to night light (p = 0.58) before age 2. These results remained even after controlling for near work.

CONCLUSION

Myopia is not associated with night light in Asian populations.

Renal dysfunction in workers exposed to inorganic lead

INTRODUCTION

We studied the relationship between renal dysfunction and occupational lead exposure in a local factory.

MATERIALS AND METHODS

A cross-sectional study with a cohort component was conducted with 55 male workers of a factory producing PVC stabilisers as subjects. Workers from this factory have been followed up with 6-monthly blood lead measurements since 1982. Two indices of overall lead exposure, i.e. the number of times a worker's blood lead exceeded 40 micrograms/dL (PbB40) and cumulative blood lead index (PbBint), were obtained from this data. Recent blood lead concentration (PbB) was measured. 4-hour creatinine clearance and various other urinary and serum markers of renal dysfunction were used as effect indices.

RESULTS

There was no relationship between PbB and any of the renal markers. However, creatinine clearance decreased significantly (P < 0.001) with increasing PbB40 and PbBint after adjustment for age and smoking habits. Urinary albumin (Ualb), urinary alpha-1 microglobulin (U alpha 1m), urinary beta-2 microglobulin (U beta 2m) and urinary retinol-binding protein (URBP) increased significantly with both increasing PbB40 and PbBint. Total urinary activity of N-acetyl-beta-D-glucosaminidase (NAG-T) and its heat-stable isoenzyme (NAG-B) increased significantly with increasing PbB40. A significant difference in renal parameters occurred when PbB40 was 1 or more.

CONCLUSIONS

We have found a positive association between overall lead exposure and renal dysfunction. The renal parameters were significantly higher among those who had at least one episode of blood lead above 40 micrograms/dL. Our findings also strengthen the case for the use of Ualb, U alpha 1m, U beta 2m, URBP, NAG-T and NAG-B as early markers of lead nephropathy.

Urinary protein excretion in Type 2 diabetes with complications

This study examined the association between urinary markers of early diabetic nephropathy and non-renal diabetic complications in 946 patients with type 2 diabetes mellitus. The association with hypertension was also studied. Data on macrovascular complications (ischaemic heart disease, stroke, peripheral vascular disease) and microvascular complications (retinopathy, peripheral neuropathy) were obtained from case records and clinical examination. Urine samples collected were analysed for albumin, beta(2)-microglobulin, retinol-binding protein (RBP), and N-acetyl-beta-D-glucosaminidase (NAG). Results showed that urinary albumin, RBP and beta(2)-microglobulin levels were higher in patients with macro- and/or microvascular complications, compared to those without. NAG levels were higher only in patients with both types of complications. A higher proportion of patients with complications had abnormally raised urinary protein and enzyme levels, compared to those without. Patients with associated hypertension had higher urinary levels of albumin and beta(2)-microglobulin, regardless of whether complications were present or not. RBP excretion was, however, markedly higher only in patients with microvascular complications, whereas hypertension did not influence NAG excretion. Urine albumin and RBP excretion were predictive of microvascular, as well as both macrovascular and microvascular complications, whereas NAG excretion was predictive of macro- and microvascular complications. These findings could mean that increased urinary protein and enzyme excretion were associated with more severe disease in these patients.

Urine protein excretion among Chinese patients with type 2 diabetes mellitus

BACKGROUND

Urinary excreton of low molecular weight proteins such as beta2-microglobulin and retinol binding protein (RBP), and enzymes such as N-acetyl-beta-D-glucosaminidase (NAG), may be useful as indicators of renal tubular dysfunction in diabetes mellitus.

OBJECTIVE

To describe the profile of urinary protein and enzyme excretion in 240 Chinese patients with type 2 diabetes mellitus in Singapore.

MATERIALS AND METHODOLOGY

Cross-sectional study of consecutive patients presenting for follow-up at a Government primary care clinic. Information was obtained from interview, physical examination and laboratory analysis. Data analysis included descriptive statistics on urinary protein and enzyme excretion, comparison of unadjusted and adjusted means of these among patient subgroups, as well as correlation with control of diabetes and other clinical parameters.

RESULTS

Albuminuria correlated with urine beta2-microglobulin (r=0.34, p<0.01) and RBP (r=0.46, p<0.01). Hypertensive patients had significantly higher mean urine albumin (geometric mean 15.13 mg/gCr) and beta2-microglobulin (363.18 microg/gCr) levels compared to patients without hypertension (7.07 mg/gCr; 219.20 microg/gCr; p<0.05). Patients with complications of diabetes also had higher albumin (15.55 vs 6.20 mg/gCr), beta2-microglobulin (344.47 vs 288.83 microg/gCr) and RBP excretion (152.02 vs 94.54 mg/gCr). Two-hour postprandial sugar correlated with beta2-microglobulin (r=0.33, p<0.01), RBP (r=0.35, p<0.01) and NAG (r=0.28, p<0.01). Urinary protein excretion did not correlate with HbA1c, fasting blood sugar, age of patient or duration since diagnosis.

CONCLUSION

These results among 240 Chinese patients in Singapore were consistent with reports from other study populations.

Myopia: gene-environment interaction

INTRODUCTION

Myopia has reached epidemic proportions in Japan, Hong Kong, Taiwan and Singapore. This review summarises the evidence for environmental and genetic factors as well as gene-environment interaction for myopia for both epidemiologic studies as well as animal models.

METHODS

A literature review was conducted after a Medline search on articles on the genetic or environmental aetiology of myopia in animal or epidemiologic studies. Articles on the methodology of gene-environment studies were also reviewed. All articles reviewed were articles published in peer-reviewed journals.

RESULTS

Cross-sectional studies have found a positive association between myopia and near work activity such as reading and writing. Likewise, laboratory research has shown that environmental factors such as visual deprivation may lead to the development of myopia in animals. While linkage studies in humans are currently being conducted to identify possible markers for myopia in the human genome, several neurotransmitters, modulators and growth factors that influence refractive development have already been identified in animal models that may help identify candidate genes. Epidemiologic studies have also evaluated the combined effects of hereditary factors, environmental factors and gene-environment interaction on myopia development.

CONCLUSIONS

Both genes and environmental factors may be related to myopia. There are no conclusive studies at present, however, that identify the nature and extent of possible gene-environment interaction. Further linkage analysis, affected sib-pair studies, and family-based association studies may better identify the nature of gene-environment interaction.

Incidence of ischaemic heart disease and stroke in Chinese, Malays and Indians in Singapore: Singapore Cardiovascular Cohort Study

INTRODUCTION

This is the first prospective cohort study in Singapore to describe the incidence of ischaemic heart disease (IHD) and stroke among Chinese, Malays and Asian Indians.

MATERIALS AND METHODS

The Singapore Cardiovascular Cohort Study is a longitudinal follow-up study on a general population cohort of 5920 persons drawn from 3 previous cross-sectional surveys. Morbidity and mortality from IHD and stroke were ascertained by record linkage using a unique identification number with the death registry, Singapore Myocardial Infarct Registry and in-patient discharge databases.

RESULTS

There were 193 first IHD events and 97 first strokes during 52,806 person-years of observation. The overall incidence of IHD was 3.8/1000 person-years and that of stroke was 1.8/1000 person-years. In both males and females, Indians had the highest IHD incidence, followed by Malays and then Chinese. For males after adjusting for age, Indians were 2.78 times (95% CI 1.86, 4.17; P < 0.0001) and 2.28 times (95% CI 1.34, 3.88; P = 0.002) more likely to get IHD than Chinese and Malays respectively. For females after adjusting for age, Indians were 1.97 times (95% CI 1.07, 3.63; P = 0.03) and 1.37 times (95% CI 0.67, 2.80; P = 0.39) more likely to get IHD than Chinese and Malays respectively. For stroke, male Chinese and Indians had higher incidence than Malays (though not statistically significant). However, in females, Malays had the highest incidence of stroke, being 2.57 times (95% CI 1.31, 5.05; P = 0.008) more likely to get stroke than Chinese after adjustment for age.

CONCLUSIONS

This prospective study of both mortality and morbidity has confirmed the higher risk of IHD in Indians. It has also found that Malay females have a higher incidence of stroke, which deserves further study because of its potential public health importance.

Incidence and survival characteristics of retinoblastoma in Singapore from 1968-1995

PURPOSE

To describe the incidence and survival of 69 Singapore residents with retinoblastoma in all Singapore hospitals from 1968-1995.

METHODS

Data of all Singapore residents diagnosed with retinoblastoma from 1968-1995 were collected by the Singapore Cancer Registry based on notifications from physicians, pathology records, hospital discharge records, and death certificates. The medical records of 46 patients were traced, and information on laterality of tumor, spread of tumor, mode of treatment, and family history of retinoblastoma was obtained. Time trends and survival characteristics of the cohort were described.

RESULTS

The incidence rate of retinoblastoma was 2.4 per 1 million for children <9 years and 11.1 per 1 million for children <5 years. The incidence of retinoblastoma has been almost uniform over time from 1968-1995, except for an apparent increase in 1988-1992. The 3-year survival rate for retinoblastoma was 83%. Survival rates were higher in children <2 years because children who present at a younger age may have tumors diagnosed at earlier stages of the disease. There was no difference in survival rates for sex, race, laterality, family history of retinoblastoma, treatment, or year of diagnosis.

CONCLUSION

Retinoblastoma is the most common eye cancer in children that may cause blindness or death. The incidence rates of retinoblastoma in Singapore have remained fairly stable over 28 years, and the survival rate is higher in younger children. This study will be helpful in monitoring future disease patterns in Asian populations.

Markers of diabetic nephropathy

It is well established that the detection of microalbuminuria in a patient with diabetes mellitus indicates the presence of glomerular involvement in early renal damage. Recent studies have demonstrated that there is also a tubular component to renal complications of diabetes, as shown by the detection of renal tubular proteins and enzymes in the urine. In fact, tubular involvement may precede glomerular involvement, as several of these tubular proteins and enzymes are detectable even before the appearance of microalbuminuria. This review looks at the studies reported so far on serum and urinary markers of diabetic nephropathy, both glomerular and tubular, and their roles in the early detection of renal damage. The advantages and disadvantages of some of these markers are also discussed. The markers reviewed include (1) glomerular--transferrin, fibronectin, and other components of glomerular extracellular matrix, and (2) tubular--low molecular weight proteins (beta 2 microglobulin, retinol binding protein, alpha 1 microglobulin, urine protein 1), other proteins such as Tamm-Horsfall protein, beta 2 glycoprotein-1, urinary enzymes (N-acetyl-beta-D-glucosaminidase, cholinesterase, gamma glutamyltranspeptidase, alanine aminopeptidase), and tubular brush-border antigen.