1
|
Fong CW. The Ross circumcision ring. Hong Kong Med J 2023; 29:366-367. [PMID: 37599407 DOI: 10.12809/hkmj-hkmms202308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/22/2023] Open
|
2
|
Beng AKL, Fong CW, Shum E, Goh CR, Goh KT, Chew SK. Where the Elderly Die: The Influence of Socio-Demographic Factors and Cause of Death on People Dying at Home. Ann Acad Med Singap 2009. [DOI: 10.47102/annals-acadmedsg.v38n8p676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Introduction: The place of death of the elderly has implications on the overall healthcare delivery system. The aim of this study is to describe where deaths of elderly occur in Singapore and to determine the association of socio-demographic characteristics and the causes of death on dying at home.
Materials and Methods: Data of 10,399 Singapore resident decedents aged 65 years and above in 2006 were obtained from the national Registry of Births and Deaths. Distributions of socio-demographic characteristics and causes of death by place of death were analysed, and associations between socio-demographic characteristics and home death for major causes of death were assessed by logistic regression models controlling for age, gender and ethnic group.
Results: Most elderly deaths occurred in hospitals (57%), followed by deaths at home (31%). The proportion of deaths at home increased with age while deaths in hospital declined with age. Significantly more elderly women died at home compared to men. Malay elderly had the highest proportion of home deaths (49%), and the lowest proportion of hospital deaths (47%). Elderly persons who died from stroke were most likely to die at home [odds ratio (OR) 2.8, 95% confidence interval (CI), 2.3-3.3] while those who died from lung and respiratory system diseases were less likely to die at home (OR, 0.7; 95% CI, 0.6-0.8).
Conclusion: Elderly people in Singapore die mainly in hospitals. About a third of them die at home. The proportion of decedents dying at home increased with age. Home deaths among the elderly are most likely in those aged 85 years and above, females, Malays, and those who die of stroke.
Key words: Ethnicity, Gender, Hospital, Place of death, Singapore
Collapse
|
3
|
Beng AKL, Fong CW, Shum E, Goh CR, Goh KT, Chew SK. Where the elderly die: the influence of socio-demographic factors and cause of death on people dying at home. Ann Acad Med Singap 2009; 38:676-683. [PMID: 19736570] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
INTRODUCTION The place of death of the elderly has implications on the overall healthcare delivery system. The aim of this study is to describe where deaths of elderly occur in Singapore and to determine the association of socio-demographic characteristics and the causes of death on dying at home. MATERIALS AND METHODS Data of 10,399 Singapore resident decedents aged 65 years and above in 2006 were obtained from the national Registry of Births and Deaths. Distributions of socio-demographic characteristics and causes of death by place of death were analysed, and associations between socio-demographic characteristics and home death for major causes of death were assessed by logistic regression models controlling for age, gender and ethnic group. RESULTS Most elderly deaths occurred in hospitals (57%), followed by deaths at home (31%). The proportion of deaths at home increased with age while deaths in hospital declined with age. Significantly more elderly women died at home compared to men. Malay elderly had the highest proportion of home deaths (49%), and the lowest proportion of hospital deaths (47%). Elderly persons who died from stroke were most likely to die at home [odds ratio (OR) 2.8, 95% confidence interval (CI), 2.3-3.3] while those who died from lung and respiratory system diseases were less likely to die at home (OR, 0.7; 95% CI, 0.6-0.8). CONCLUSION Elderly people in Singapore die mainly in hospitals. About a third of them die at home. The proportion of decedents dying at home increased with age. Home deaths among the elderly are most likely in those aged 85 years and above, females, Malays, and those who die of stroke.
Collapse
Affiliation(s)
- Arthur K L Beng
- Healthcare Finance and Corporate Services Division, Ministry of Health, Singapore. bengkla@pacifi c.net.sg
| | | | | | | | | | | |
Collapse
|
4
|
Amerasinghe N, Aung T, Cheung N, Fong CW, Wang JJ, Mitchell P, Saw SM, Wong TY. Evidence of retinal vascular narrowing in glaucomatous eyes in an Asian population. Invest Ophthalmol Vis Sci 2008; 49:5397-402. [PMID: 18719076 DOI: 10.1167/iovs.08-2142] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To examine the relationship between retinal vascular caliber and glaucoma in an Asian population. METHODS A population-based, cross-sectional study of 3019 persons of Asian Malay ethnicity aged 40 to 80 years residing in Singapore. All participants had dilated digital retinal photographs taken of both eyes. From these, retinal vascular caliber was measured with a computer-based technique according to a standardized protocol. Glaucoma was diagnosed based on the International Society of Geographic and Epidemiologic Ophthalmology classification and included people with glaucomatous optic neuropathy and compatible visual field loss. RESULTS There were 127 (4.2%) participants with glaucoma. Mean retinal arteriolar and venular calibers were significantly narrower in persons with than in those without glaucoma (136.4 microm vs. 139.7 microm, P = 0.02 and 209.2 microm vs. 219.7 microm, P < 0.001, respectively). After adjusting for age, sex, smoking, IOP, and other vascular risk factors, persons with narrower retinal arteriolar and venular caliber were more likely to have glaucoma (odds ratio [OR], 1.29; 95% confidence interval [CI], 1.07-1.56 and OR, 1.49; 95% CI, 1.24-1.79, for each SD reduction in arteriolar and venular caliber, respectively) and a vertical cup-to-disc ratio >or= 0.7 (OR, 1.35; 95% CI, 1.12-1.63 and OR, 1.65; 95% CI, 1.38-1.98, respectively). Retinal vascular caliber was not associated with intraocular pressure. CONCLUSIONS These findings support an association of narrower retinal arteriolar and venular caliber changes with glaucomatous optic neuropathy, independent of intraocular pressure.
Collapse
|
5
|
Foong AWP, Fong CW, Wong TY, Saw SM, Heng D, Foster PJ. Visual Acuity and Mortality in a Chinese Population. Ophthalmology 2008; 115:802-7. [PMID: 17765312 DOI: 10.1016/j.ophtha.2007.04.066] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2006] [Revised: 04/30/2007] [Accepted: 04/30/2007] [Indexed: 11/15/2022] Open
Abstract
OBJECTIVE To examine the relationship between visual acuity and mortality in a Chinese population. DESIGN Population-based cohort study. PARTICIPANTS Chinese persons in Singapore ages 40 to 79 years at baseline examination. METHODS The Tanjong Pagar Study in Singapore examined 1232 persons (response rate, 71.8%) at the baseline examination in 1997 and 1998. Participants had measurements of presenting and best-corrected visual acuity (VA) using standardized protocols. Mortality data were obtained from the National Death Registry, which linked subjects who had died since the baseline examination. Cause of death was determined from the International Classification of Diseases 9 codes. Analysis was performed on 1225 (99.4%) participants with VA data. MAIN OUTCOME MEASURE All-cause mortality. RESULTS By December 31, 2004 (median follow-up, 6.8 years), 126 persons had died. Participants with presenting VA in the better eye worse than 20/40 (logarithm of the minimum angle of resolution [logMAR] score, 0.3) had a significantly higher mortality rate (hazard ratio [HR], 2.9; 95% confidence interval [CI], 1.4-6.3, adjusting for age, gender, hypertension, diabetes, smoking, heart attack, stroke, and income) as compared with participants with VA of 20/20 (logMAR, 0.0). Associations were similar for best-corrected VA in the better eye (HR, 2.7; 95% CI, 1.4-5.5). Among clinic participants with logMAR VA measurements, each 1-line difference in presenting VA (logMAR gain, 0.10) was associated with a 4-fold increased risk of mortality (HR, 4.4; 95% CI, 1.9-10.2). CONCLUSIONS In this Chinese population in Singapore, visual impairment was associated independently with an increased risk of mortality.
Collapse
|
6
|
Fong CW, Bhalla V, Heng D, Chua AV, Chan ML, Chew SK. Educational inequalities associated with health-related behaviours in the adult population of Singapore. Singapore Med J 2007; 48:1091-1099. [PMID: 18043835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
INTRODUCTION Socioeconomic differences in health-related behaviours have been widely studied in the Western populations, but are seldom considered in Asian populations. We examined the effect of education attainment on health-related behaviours (physical activity, cigarette smoking and alcohol consumption) among non-institutionalised Singaporeans aged 18-69 years. METHODS We used data from the Singapore National Health Survey 2004. Information on physical activity, cigarette smoking, alcohol consumption and sociodemographic characteristics was collected from 4,084 adults. Age-adjusted prevalence of the three health-related behaviours by educational attainment was calculated by the direct method. Logistic regression models, adjusted for age, gender, ethnic group and employment status, were used to estimate the odds ratio and 95% confidence interval, in order to study the prevalence of health-related behaviours according to educational attainment. RESULTS The prevalence of physical inactivity, daily smoking and regular alcohol consumption was found to be consistently highest among men and women with the least education. Prevalence of physical inactivity and smoking was inversely related to educational attainment for both genders. However, no clear gradient was found between education and alcohol consumption for men and women. CONCLUSION Less-educated Singaporeans were more likely to smoke daily, drink alcohol regularly or not to exercise regularly. Health promotion policies or programmes aimed at encouraging healthy lifestyles in the Singapore population should take into account the educational inequalities in these health-related behaviours.
Collapse
Affiliation(s)
- C W Fong
- Epidemiology & Disease Control Division, Ministry of Health Singapore, 16 College Road, College of Medicine Building, Singapore 169854.
| | | | | | | | | | | |
Collapse
|
7
|
Abstract
AIMS To present trends in alcohol consumption between 1992 and 2004 in Singapore. METHODS Alcohol consumption data were derived from national health surveys conducted in 1992, 1998 and 2004. Age-adjusted prevalence of frequent (drinking 1-4 days a week), regular (drinking more than 4 days a week) and binge (having five or more drinks during a drinking session at least once in the month) drinking by gender and age group for the three surveys were compared. Multivariate analyses for binge drinking in 2004 were performed using logistic regression models. RESULTS Prevalence of frequent, regular and binge drinking increased between 1992 and 2004. Prevalence increase in binge drinking was highest (from 5.1 to 10.0%), followed by frequent drinking (from 4.5 to 7.5%) and regular drinking (from 2.9 to 3.1%). Uptake in binge drinking increased in both genders and across all age groups but was most evident among adults aged 18-29. Frequent drinking increase was observed for both genders but was most pronounced among women aged 18-29. The level of regular drinking declined in men but increased in women, especially those aged 18-29 and 30-49. Being younger, male, separated, divorced or widowed, a current smoker, or having a monthly household income of S$6000 and above were attributes positively associated with binge drinking. CONCLUSIONS Alcohol consumption, especially binge drinking, has increased among Singaporeans between 1992 and 2004. There is gender convergence in alcohol consumption.
Collapse
Affiliation(s)
- Wei-Yen Lim
- Epidemiology and Disease Control Division, Ministry of Health Singapore, 16 College Road, College of Medicine Building, Singapore 169854, Singapore.
| | | | | | | | | | | |
Collapse
|
8
|
Bhalla V, Fong CW, Chew SK, Satku K. Changes in the levels of major cardiovascular risk factors in the multi-ethnic population in Singapore after 12 years of a national non-communicable disease intervention programme. Singapore Med J 2006; 47:841-50. [PMID: 16990958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
INTRODUCTION The National Healthy Lifestyle Programme, a population-wide non-communicable disease intervention programme, was started in 1992. A National Health Survey is carried out every six years to evaluate the impact of this programme on the cardiovascular risk factor profile of the resident population of Singapore. METHODS The 2004 National Health Survey (NHS 04) was a population-based survey carried out over a period of four months from September to December 2004. A combination of disproportionate stratified sampling and systematic sampling was used to select a representative sample (n=7,078) for the survey. The reference population comprised 2.4 million multi-racial Singaporeans aged 18-69 years. Anthropometric and blood pressure measurements were carried out on all subjects and blood samples were taken for biochemical analysis. The results were compared with those of a similar survey conducted in 1998. RESULTS A total of 4,084 Singapore residents took part in the survey, giving a response rate of 57.7 percent. The age-standardised prevalence of hypertension (greater than or equal to 140/90 mmHg) in Singapore residents aged 30-69 years decreased from 28.0 percent in 1998 to 24.0 percent (p-value is less than 0.001) in 2004. The prevalence of high total cholesterol (greater than or equal to 6.2 mmol/L) among those aged 18-69 years fell from 26.0 percent in 1998 to 18.1 percent (p-value is less than 0.001) in 2004. The prevalence of diabetes mellitus in residents aged 18-69 years in 2004 was 7.8 percent, compared to the 1998 level of 9.5 percent (p-value is less than 0.01). The level of obesity (body mass index is greater than or equal to 30 kg/sqm) increased slightly from 6.2 percent in 1998 to 6.8 percent (p-value equals 0.1627). The prevalence of daily smoking decreased from 15.0 percent in 1998 to 12.5 percent in 2004 (p-value is less than 0.001), while that of regular exercise increased from 17.0 percent to 25.0 percent (p-value is less than 0.001). Ethnic differences in the prevalence of diabetes mellitus, hypertension, hypercholesterolaemia, and exercise were observed. CONCLUSION The NHS 04 results suggest that the National Healthy Lifestyle Programme significantly decreased daily smoking, high blood cholesterol and hypertension, and increased regular exercise over 1998 levels. The results also suggest that the programme stabilised the prevalence of obesity and diabetes mellitus.
Collapse
Affiliation(s)
- V Bhalla
- Epidemiology and Disease Control Division, Ministry of Health, 16 College Road, Singapore 169854.
| | | | | | | |
Collapse
|
9
|
Wei S, Ong WY, Thwin MM, Fong CW, Farooqui AA, Gopalakrishnakone P, Hong W. Group IIA secretory phospholipase A2 stimulates exocytosis and neurotransmitter release in pheochromocytoma-12 cells and cultured rat hippocampal neurons. Neuroscience 2003; 121:891-8. [PMID: 14580939 DOI: 10.1016/s0306-4522(03)00525-6] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Recent evidence shows that secretory phospholipase A2 (sPLA2) may play a role in membrane fusion and fission, and may thus affect neurotransmission. The present study therefore aimed to elucidate the effects of sPLA2 on vesicle exocytosis. External application of group IIA sPLA2 (purified crotoxin subunit B or purified human synovial sPLA2) caused an immediate increase in exocytosis and neurotransmitter release in pheochromocytoma-12 (PC12) cells, detected by carbon fiber electrodes placed near the cells, or by changes in membrane capacitance of the cells. EGTA and a specific inhibitor of sPLA2 activity, 12-epi-scalaradial, abolished the increase in neurotransmitter release, indicating that the effect of sPLA2 was dependent on calcium and sPLA2 enzymatic activity. A similar increase in neurotransmitter release was also observed in hippocampal neurons after external application of sPLA2, as detected by changes in membrane capacitance of the neurons. In contrast to external application, internal application of sPLA2 to PC12 cells and neurons produced blockade of neurotransmitter release. Our recent studies showed high levels of sPLA2 activity in the normal rat hippocampus, medulla oblongata and cerebral neocortex. The sPLA2 activity in the hippocampus was significantly increased, after kainate-induced neuronal injury. The observed effects of sPLA2 on neurotransmitter release in this study may therefore have a physiological, as well as a pathological role.
Collapse
Affiliation(s)
- S Wei
- Institute of Molecular and Cell Biology, National University of Singapore 117609, Singapore
| | | | | | | | | | | | | |
Collapse
|
10
|
Koh WP, Taylor MB, Hughes K, Chew SK, Fong CW, Phoon MC, Kang KL, Chow VTK. Seroprevalence of IgG antibodies against Chlamydia pneumoniae in Chinese, Malays and Asian Indians in Singapore. Int J Epidemiol 2002; 31:1001-7. [PMID: 12435775 DOI: 10.1093/ije/31.5.1001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Chlamydia pneumoniae, a bacterium that causes respiratory infections, is probably under-diagnosed. There is also interest in its possible role in the aetiology of coronary heart disease. This is the first population-based seroprevalence survey of C. pneumoniae infection in Singapore. METHODS A random sample of 1,068 people aged 18-69 years was selected from the participants of the Singapore National Health Survey conducted in 1998. Sera and data on certain clinical measurements and conditions had been collected. IgG antibodies for C. pneumoniae were detected using an indirect microimmunofluorescence test and positivity graded. Seropositivity was defined as IgG titre >/=1:16. RESULTS There were no statistically significant differences in the prevalence rates of seropositivity to C. pneumoniae for age group 18-69 years among the three ethnic groups, i.e. Chinese (males 76.7%, females 68.3%), Malays (males 75.4%, females 59.1%), and Asian Indians (males 74.6%, females 59.4%). The seropositivity rate for people aged 18-69 years in Singapore was 75.0% for males and 65.5% for females (difference of 9.5%, P < 0.001). In both genders combined, seropositivity increased from 46.5% in the age group 18-29 to reach a plateau of 78.9% in the age group 40-49, which remained stable to 60-69 years. There was no association of seropositivity with smoking, diabetes mellitus, hypertension or body mass index after adjustment for age and gender. CONCLUSION The high prevalence rates in our study population and the higher rate in males compared to females are consistent with studies from other parts of the world. No significant difference in prevalence rates was observed among Chinese, Malays and Indians. The pattern of rising and levelling off of seropositivity with age suggests that C. pneumoniae infection occurs early in life, and in older ages the high level of seropositivity is probably maintained by re-infections or chronic infections. Chlamydia pneumoniae infection was not found to be associated with the cardiovascular risk factors examined.
Collapse
Affiliation(s)
- Woon Puay Koh
- Department of Community, Occupational and Family Medicine, National University of Singapore, Singapore
| | | | | | | | | | | | | | | |
Collapse
|
11
|
James L, Fong CW, Foong BH, Wee MK, Chow A, Shum E, Chew SK. Hepatitis B Seroprevalence Study 1999. Singapore Med J 2001; 42:420-4. [PMID: 11811609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Hepatitis B is a disease of public health importance in Singapore. A study was conducted in 1999 to estimate the overall and gender-, age- and ethnic-specific prevalence of hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg) and antibody to hepatitis B surface antigen in the Singapore population. A cross-sectional sample of the Singapore population constituting 4,698 Singapore residents aged 18-69 years was surveyed. This was the first time a large-scale study has been conducted to assess the hepatitis B seroprevalence rates in the Singapore population. The overall prevalence of the HBsAg in the general population was estimated to be about 4%. About 13% of the HBsAg carriers were also HBeAg positive. Only about 40% of the population had immunity to hepatitis B virus either through immunisation or from previous exposure to the virus. There was still a large proportion (60%) of the population who had no immunity, especially the younger age group of 18-29 years where only 28% had immunity. There is a need to strengthen the hepatitis B immunisation programme to reach out to those who have no immunity, especially the young adults.
Collapse
Affiliation(s)
- L James
- Communicable Diseases Branch, Epidemiology and Disease Control Division, Ministry of Health, Singapore.
| | | | | | | | | | | | | |
Collapse
|
12
|
Abstract
Regulators of G-protein signaling (RGS) are GTPase-activating proteins (GAP) for activated Galpha subunits. We found that mouse RGS16, when expressed in HEK293T cells, is phosphorylated constitutively at serine 194 based on in vivo orthophosphate labeling experiments, while serine 53 is phosphorylated in a ligand-dependent manner upon stimulation by epinephrine in cells expressing the alpha2A adrenergic receptor. Phosphorylation on both sites impairs its GAP activity and subsequent attenuation on heterotrimeric G-protein-stimulated extracellular signal-regulated protein kinase activity. This is the first report of RGS functional downregulation by phosphorylation via a G-protein-coupled receptor.
Collapse
Affiliation(s)
- C Chen
- Regulatory Biology Group, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609, Singapore
| | | | | | | |
Collapse
|
13
|
Fong CW, Zhang Y, Neo SY, Lin SC. Specific induction of RGS16 (regulator of G-protein signalling 16) mRNA by protein kinase C in CEM leukaemia cells is mediated via tumour necrosis factor alpha in a calcium-sensitive manner. Biochem J 2000; 352 Pt 3:747-53. [PMID: 11104682 PMCID: PMC1221513] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
The RGS (regulator of G-protein signalling) proteins are GTPase-activating proteins for activated Galpha subunits. We investigated the effects of protein kinase C (PKC) on RGS proteins in various T cell lines by treating them with PMA. mRNA levels of both RGS16 and tumour necrosis factor alpha (TNFalpha) were found to be up-regulated in CEM leukaemia cells in a PKC-dependent manner. Mezerein, a non-phorbol-ester activator of PKC, also elevated RGS16 and TNFalpha mRNA levels, while the specific PKC inhibitor Go6983 abrogated their expression. In view of the slower kinetics of PMA-induced RGS16 expression and the tight correlation between TNFalpha and RGS16 mRNA induction among the cell lines studied, we suggest that activation of PKC up-regulates RGS16 via TNFalpha. Indeed, addition of recombinant TNFalpha to CEM cells rapidly stimulated RGS16 mRNA expression independently of PKC. Furthermore, mobilization of calcium by A23187 and thapsigargin blocked the TNFalpha-mediated induction of RGS16, which was reversed by EGTA and by the immunosuppressants FK506 and cyclosporin A, suggesting that the calcineurin/NF-AT (nuclear factor of activated T cells) pathway may repress the up-regulation process. Our results demonstrate for the first time that activation of PKC induces RGS16 expression via TNFalpha in a calcium-sensitive manner, thereby implicating RGS16 in the regulation of T cell responses to inflammation.
Collapse
Affiliation(s)
- C W Fong
- Regulatory Biology Group, Institute of Molecular and Cell Biology, 30 Medical Drive, Singapore 117609
| | | | | | | |
Collapse
|
14
|
Fong CW, Milligan G. Analysis of agonist function at fusion proteins between the IP prostanoid receptor and cognate, unnatural and chimaeric G-proteins. Biochem J 1999; 342 ( Pt 2):457-63. [PMID: 10455034 PMCID: PMC1220484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Direct measures of G-protein activation based on guanine nucleotide exchange and hydrolysis are frequently impossible to monitor for receptors which interact predominantly with G(s)alpha. An isolated FLAG (Asp-Tyr-Lys-Asp-Asp-Asp-Asp-Lys)-epitope-tagged human IP prostanoid receptor and fusion proteins generated between this form of the receptor and the alpha subunits of its cognate G-protein G(s), G(i1), a G-protein which it fails to activate in co-expression studies, and a chimaeric G(i1)-G(s)6 (a form of G(i1) in which the C-terminal six amino acids were replaced with the equivalent sequence of G(s)) were stably expressed in HEK293 cells. These were detected by [(3)H]ligand-binding studies and by immunoblotting with both an anti-FLAG antibody and with appropriate antisera to the G-proteins. Each construct displayed similar affinity to bind the agonist iloprost. Iloprost stimulated adenylate cyclase activity in clones expressing both IP prostanoid receptor and the IP prostanoid receptor-G(s)alpha fusion protein, and both constructs were shown to interact with and activate endogenously expressed G(s)alpha. Addition of iloprost to membranes of cells expressing the isolated receptor resulted in a small stimulation of high-affinity GTPase activity. Iloprost produced no stimulation of GTPase activity which could be attributed to the IP prostanoid receptor-G(i1)alpha fusion. However, the fusion proteins containing either G(s)alpha or G(i1)-G(s)6alpha produced substantially greater stimulation of GTPase activity than the isolated IP prostanoid receptor. Treatment of cells expressing the IP prostanoid receptor-G(i1)-G(s)6alpha fusion protein with a combination of cholera and pertussis toxins allowed direct measurement of agonist activation of the receptor-linked G-protein. Normalization of such results for levels of expression of the IP prostanoid receptor constructs demonstrated a 5-fold higher stimulation of GTPase activity when using the G(s)alpha-containing fusion protein and a 9-fold improvement when using the fusion protein containing G(i1)-G(s)6alpha to detect G-protein activation compared with expression of the isolated receptor.
Collapse
Affiliation(s)
- C W Fong
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, U.K
| | | |
Collapse
|
15
|
Milligan G, Groarke DA, McLean A, Ward R, Fong CW, Cavalli A, Drmota T. Diversity in the signalling and regulation of G-protein-coupled receptors. Biochem Soc Trans 1999; 27:149-54. [PMID: 10093724 DOI: 10.1042/bst0270149] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- G Milligan
- Division of Biochemistry and Molecular Biology, University of Glasgow, Scotland, U.K
| | | | | | | | | | | | | |
Collapse
|
16
|
Fong CW, Bahia DS, Rees S, Milligan G. Selective activation of a chimeric Gi1/Gs G protein alpha subunit by the human IP prostanoid receptor: analysis using agonist stimulation of high affinity GTPase activity and [35S]guanosine-5'-O-(3-thio)triphosphate binding. Mol Pharmacol 1998; 54:249-57. [PMID: 9687565 DOI: 10.1124/mol.54.2.249] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A FLAG-tagged form of the human IP prostanoid receptor was expressed stably in HEK 293 cells. This bound [3H]iloprost with high affinity and stimulated cAMP production when exposed to agonist. Iloprost produced weak stimulation of GTPase activity and [35S]guanosine-5'-O-(3-thio)triphosphate binding in membranes of these cells. Pretreatment of cells with pertussis toxin did not modify iloprost-mediated stimulation, but this was blocked by cholera toxin. The effects of iloprost were not increased by coexpression of either Gsalpha or Gi1alpha. In contrast, coexpression of a chimeric G protein alpha subunit in which the carboxyl-terminal six amino acids of Gi1alpha were altered to those of Gsalpha resulted in robust stimulation by iloprost. Because the chimeric G protein alpha subunit (Gi1/Gs6alpha) is not a substrate for either pertussis or cholera toxin, pretreatment of cells coexpressing the IP prostanoid receptor and Gi1/Gs6alpha with a mixture of these toxins resulted in resolution of the signal derived from activation of the chimeric G protein. Agonist-stimulated [35S]guanosine-5'-O-(3-thio)triphosphate binding and GTPase activity assays are the most commonly used strategies to examine interactions between G protein-coupled receptors and G proteins. These usually are not appropriate for receptors such as the IP prostanoid receptor that interact with G proteins with low rates of guanine nucleotide exchange and hydrolysis. Chimeric G proteins such as Gi1/Gs6alpha that allow appropriate receptor contacts to be converted to the higher nucleotide turnover rates typical of the Gi family G proteins can overcome this and offer a novel means to examine agonist function at such receptors.
Collapse
Affiliation(s)
- C W Fong
- Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, University of Glasgow, Glasgow G12 8QQ, Scotland
| | | | | | | |
Collapse
|
17
|
Fong CW, Siddiqui AH, Mark DF. Characterization of protein complexes formed on the repressor elements of the human tumor necrosis factor alpha gene. J Interferon Cytokine Res 1995; 15:887-95. [PMID: 8564711 DOI: 10.1089/jir.1995.15.887] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Human tumor necrosis factor alpha (TNF-alpha) is an important cytokine responsible for pleiotropic effects in vivo. The expression of TNF-alpha is under both positive and negative regulation. Previously we showed that a 108 bp region (-280 to -172) in the TNF-alpha promoter represses TNF-alpha transcription in U937 cells. We also demonstrated that a smaller region of the promoter spanning base pairs -254 and -230 is sufficient for repressor function. This 25 bp TNF-alpha repressor site (TRS) contains a 10 bp sequence homologous to the binding site of activator protein AP-2, yet it does not bind the AP-2 protein. In this study, we demonstrate that this 10 bp core sequence is an essential element for the repressor function of the TRS. Using gel retardation analysis with the 108 bp repressor element and the TRS as probes, multiple specific DNA binding complexes have been identified from U937 nuclear extracts. The complexes B, C, and D on the 108 bp probe and the three major complexes on the 25 bp TRS probe are also present in Jurkat and Mono Mac 6 cells, and their abundance in these cell lines seems to correlate with their postulated repressor function. We have demonstrated that the major TRS binding proteins, with estimated MWs of 30-60 kD, copurify on a heparin agarose column and on a DNA affinity column conjugated with the 10 bp core sequence.
Collapse
Affiliation(s)
- C W Fong
- Department of Microbial Chemotherapeutics and Molecular Genetics, Merck Research Laboratories, Rahway, NJ 07065, USA
| | | | | |
Collapse
|
18
|
Mokhtar MB, Awaluddin AB, Fong CW, Woojdy WM. Lead in blood and hair of population near an operational and a proposed area for copper mining, Malaysia. Bull Environ Contam Toxicol 1994; 52:149-154. [PMID: 8130410 DOI: 10.1007/bf00197371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Affiliation(s)
- M B Mokhtar
- Faculty of Science and Natural Resources, Universiti Kebangsaan Malaysia, Kota Kinabalu
| | | | | | | |
Collapse
|
19
|
Fong CW, Grant HG. The effect of side chain conformation on the carbon-13 substituent chemical shifts of N-substituted benzamides. Aust J Chem 1981. [DOI: 10.1071/ch9811205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The carbon-13 substituent
chemical shifts of the ipso and carbonyl atoms in the para-substituted series
Z-C6H4CONY2 (where Y = Me, Pri,
Ph) have been measured at low dilution in (D)chloroform, and dimethyl
sulfoxide. The DSP equation has been shown to hold for varying side chain
conformations with high precision when the same resonance substituent parameter
is used. Analysis of these data by the DSP equation indicates that the 'reverse
substituent chemical shift effect' for the carbonyl atom is substantially due
to a localized polarization of the π-electron system of the amide side
chain. The ratio of localized to extended π-polarization of the β
position of the amide side chain has been estimated. It is suggested that the
effective dielectric constant term for the transmission of field effects by the
cavity model varies with side chain conformation. The Cl
substituent shifts have been discussed in terms of the shift-charge ratio. A
variable-temperature study of the DSP parameters indicates an insignificant temperature
effect provided rotation around the benzene ring to amide side chain bond is
rapid.
Collapse
|
20
|
Abstract
The structures of the N-benzoyl
derivatives of aziridine, azetidine,
pyrrolidine, piperidine, hexamethyleneimine and heptamethyleneimine
in solution have been investigated by 13C n.m.r. spectroscopy. In
conjunction with literature crystal structure and dynamic intramolecular
exchange data, it has been concluded that N-benzoylaziridine and N-benzoylazetidine possess pyrimidal
nitrogen atoms in solution. The N-benzoyl derivatives of pyrrolidine,
�piperidine, hexamethyleneimine and heptamethyleneimine
have planar or near planar nitrogen atoms.
Collapse
|
21
|
Abstract
The torsional angles in 30 N-substituted benzamides and related
compounds have been estimated by the use of the 13C substituent
chemical shifts of the meta and para carbon
atoms. Steric interaction between the N-substituted
groups and the ortho
hydrogen atoms of the benzene ring is the major determinant of non-planarity in
these systems. A linear relationship between steric substituent constants of
the N-substituted groups of some
benzamides and the torsional angles is proposed. Dynamic processes involving rotation
about the C-N bond, nitrogen inversion and ring inversion contribute a dynamic
steric effect to the overall steric interaction. The preferred conformations of
some N-substituted groups is also
discussed.
Collapse
|
22
|
Abstract
The interaction of dimethyl
sulfoxide with N-benzoyl amino acids in deuterochloroform has been investigated
by 13C n.m.r. spectroscopy. Examination of the chemical shifts of
the benzene ring reveals that intermolecular hydrogen bonding between dimethyl
sulfoxide and the amido-hydrogen atom increase the effective steric size of the
amino hydrogen, resulting in an increase in the torsional angle between the
benzene ring and the C(O)NHCH(R)COOH side chain. Self-association of N- benzoyl
amino acids in deuterochloroform occurs largely through two COOH...O=C hydrogen
bonds and does not involve intermolecular hydrogen bonding to the N-H proton.
Collapse
|
23
|
Abstract
The electronic effects of
the halogen-substituted methyl groups, CHnX3-n, where X
is F, Cl, Br or I, have been examined by 13C
n.m.r, spectroscopy in a series of α-halogen-substituted toluenes. The
substituent chemical shifts of all carbon atoms, as well as the σI and σR0
substituent parameters derived from a dual substituent parameter (DSP)
analysis, are examined in terms of hyperconjugative and π-inductive
substituent effects. Bulky CHnX3-n substituents cause
molecular deformations of the benzene ring, consequently invalidating the
derivation of substituent parameters from a DSP analysis.
Collapse
|
24
|
Abstract
The torsional
angles in 31 N-phenyl-substituted azole derivatives have been estimated by use
of the 13C substituent chemical shifts of the meta and para carbon
atoms. Steric interaction between the C 5 substituent on the azole rings and
the ortho hydrogen atoms of the benzene ring is the major cause of
non-planarity in these compounds. The azole rings undergo structural
deformation with varying substituents on the azole ring. The inductive effect
of a number of azole and azolium rings is discussed.
Collapse
|
25
|
Abstract
Intramolecular hydrogen
bonding in o-hydroxy-, o-amino- and o-mercapto- N,N-dimethylbenzamide has been
examined with the help of 1H, 13C n.m.r. and infrared
spectroscopy, a study of barriers to rotation about the C- N bond, and a study
of substituent effects using a multi-substituent parameter equation. The cyclic
intramolecular hydrogen-bonded structure for the o-mercapto compound is
non-planar, and conformational isomers have been detected. The order of
relative energies of the hydrogen bonds formed in o-substituted N,N-dimethylbenzamides
is OH > NH2 > SH, as determined from a rotational barrier
probe. It has beenverified that intramolecular
hydrogen bonding causes a downfield shift of the 13C n.m.r. chemical
shift of the carbonyl group in these compounds.
Collapse
|
26
|
Piltingsrud HV, Fong CW, Odland LT. An evaluation of ultraviolet radiation personnel hazards from selected 400-watt high intensity discharge lamps. Am Ind Hyg Assoc J 1978; 39:406-13. [PMID: 677021 DOI: 10.1080/0002889778507779] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
A study of selected mercury and multi-vapor lamps, commonly used for working environment illumination, was underta ken to evaluate the scope of the ultraviolet personnel hazards one may expect under various operating conditions of the lamps. Spectral irradiance measurements were made for operating conditions with and without reflector-type luminaires, glass covers on luminaries and outer glass bulbs on the lamps.
Collapse
|
27
|
Fong CW, Lincoln SF, Williams EH. Carbon-13 N.M.R. chemical shifts and rotational barriers of ortho-substituted N,N-dimethylbenzamides. Aust J Chem 1978. [DOI: 10.1071/ch9782623] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The barriers to rotation
about the carbon-nitrogen bond and the carbon- 13 N.M.R. chemical shifts of a
series of 2-substituted N,N- dimethylbenzamides have been measured. The
substituent effects have been examined by a multi-substituent parameter method
incorporating a steric effect parameter. The barriers to rotation are subject
to a large steric effect, whilst the carbon-13 chemical shifts of the carbonyl
group and the methyl groups are dominated by the resonance effect.
Collapse
|
28
|
Fong CW, Lincoln SF, Williams EH. Carbon-13 N.M.R. chemical shifts and rotational barriers of para-substituted N,N-dimethylbenzamides. Aust J Chem 1978. [DOI: 10.1071/ch9782615] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The carbon-13 N.M.R.
chemical shifts for a series of para-substituted N,N-dimethylbenzamides have
been measured. The substituent induced 13C shifts have been examined
by a dual substituent parameter (DSP) method using Hammett-type constants. The
barriers to rotation have also been correlated with Hammett-type constants by
the DSP method and related to 13C substituent induced shifts.
Substituent effects of the bromomethyl, dibromomethyl and tribromomethyl groups
have been examined by using the chemical shift and rotational barrier probes.
Collapse
|
29
|
Piltingsrud HV, Odland LT, Fong CW. An evaluation of fluorescent light sources for use in phototherapy of neonatal jaundice. Am Ind Hyg Assoc J 1976; 37:437-44. [PMID: 961603 DOI: 10.1080/0002889768507489] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
An evaluation of fluorescent lamps for use in the phototherapy of neonatal jaundice was undertaken by making spectral irradiance measurements of each lamp. Conclusions are drawn on the usefulness of current methods of measuring exposure dose to radiation from the lamps. UV hazards from the lamps are evaluated.
Collapse
|
30
|
|