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1.
Atmos Environ (1994) ; 244: 117834, 2021 Jan 01.
Article in English | MEDLINE | ID: mdl-32895604

ABSTRACT

Global aviation operations contribute to anthropogenic climate change via a complex set of processes that lead to a net surface warming. Of importance are aviation emissions of carbon dioxide (CO2), nitrogen oxides (NOx), water vapor, soot and sulfate aerosols, and increased cloudiness due to contrail formation. Aviation grew strongly over the past decades (1960-2018) in terms of activity, with revenue passenger kilometers increasing from 109 to 8269 billion km yr-1, and in terms of climate change impacts, with CO2 emissions increasing by a factor of 6.8 to 1034 Tg CO2 yr-1. Over the period 2013-2018, the growth rates in both terms show a marked increase. Here, we present a new comprehensive and quantitative approach for evaluating aviation climate forcing terms. Both radiative forcing (RF) and effective radiative forcing (ERF) terms and their sums are calculated for the years 2000-2018. Contrail cirrus, consisting of linear contrails and the cirrus cloudiness arising from them, yields the largest positive net (warming) ERF term followed by CO2 and NOx emissions. The formation and emission of sulfate aerosol yields a negative (cooling) term. The mean contrail cirrus ERF/RF ratio of 0.42 indicates that contrail cirrus is less effective in surface warming than other terms. For 2018 the net aviation ERF is +100.9 milliwatts (mW) m-2 (5-95% likelihood range of (55, 145)) with major contributions from contrail cirrus (57.4 mW m-2), CO2 (34.3 mW m-2), and NOx (17.5 mW m-2). Non-CO2 terms sum to yield a net positive (warming) ERF that accounts for more than half (66%) of the aviation net ERF in 2018. Using normalization to aviation fuel use, the contribution of global aviation in 2011 was calculated to be 3.5 (4.0, 3.4) % of the net anthropogenic ERF of 2290 (1130, 3330) mW m-2. Uncertainty distributions (5%, 95%) show that non-CO2 forcing terms contribute about 8 times more than CO2 to the uncertainty in the aviation net ERF in 2018. The best estimates of the ERFs from aviation aerosol-cloud interactions for soot and sulfate remain undetermined. CO2-warming-equivalent emissions based on global warming potentials (GWP* method) indicate that aviation emissions are currently warming the climate at approximately three times the rate of that associated with aviation CO2 emissions alone. CO2 and NOx aviation emissions and cloud effects remain a continued focus of anthropogenic climate change research and policy discussions.

2.
BJOG ; 128(3): 614, 2021 02.
Article in English | MEDLINE | ID: mdl-32772498
3.
BJOG ; 127(4): 490-499, 2020 03.
Article in English | MEDLINE | ID: mdl-31778255

ABSTRACT

OBJECTIVE: To determine the association between maternal lipaemia and neonatal anthropometrics in Malaysian mother-offspring pairs. DESIGN: Prospective observational cohort study. SETTING: Single tertiary multidisciplinary antenatal clinic in Malaysia. POPULATION: A total of 507 mothers: 145 with gestational diabetes mellitus (GDM); 94 who were obese with normal glucose tolerance (NGT) (pre-gravid body mass index, BMI ≥ 27.5 kg/m2 ), and 268 who were not obese with NGT. METHODS: Maternal demographic, anthropometric, and clinical data were collected during an interview/examination using a structured questionnaire. Blood was drawn for insulin, C-peptide, triglyceride (Tg), and non-esterified fatty acid (NEFA) during the 75-g 2-hour oral glucose tolerance test (OGTT) screening, and again at 36 weeks of gestation. At birth, neonatal anthropometrics were assessed and data such as gestational weight gain (GWG) were extracted from the records. MAIN OUTCOME MEASURES: Macrosomia, large-for-gestational-age (LGA) status, cohort-specific birthweight (BW), neonatal fat mass (NFM), and sum of skinfold thickness (SSFT) > 90th centile. RESULTS: Fasting Tg > 95th centile (3.6 mmol/L) at screening for OGTT was independently associated with LGA (adjusted odds ratio, aOR 10.82, 95% CI 1.26-93.37) after adjustment for maternal glucose, pre-gravid BMI, and insulin sensitivity. Fasting glucose was independently associated with a birthweight ratio (BWR) of >90th centile (aOR 2.06, 95% CI 1.17-3.64), but not with LGA status, in this well-treated GDM cohort with pre-delivery HbA1c of 5.27%. In all, 45% of mothers had a pre-gravid BMI of <23 kg/m2 and 61% had a pre-gravid BMI of ≤ 25 kg/m2 , yet a GWG of >10 kg was associated with a 4.25-fold risk (95% CI 1.71-10.53) of BWR > 90th centile. CONCLUSION: Maternal lipaemia and GWG at a low threshold (>10 kg) adversely impact neonatal adiposity in Asian offspring, independent of glucose, insulin resistance and pre-gravid BMI. These may therefore be important modifiable metabolic targets in pregnancy. TWEETABLE ABSTRACT: Maternal lipids are associated with adiposity in Asian babies independently of pre-gravid BMI, GDM status, and insulin resistance.


Subject(s)
Birth Weight , Fetal Macrosomia/blood , Hyperlipidemias/blood , Adult , Asian People , Body Mass Index , Case-Control Studies , Female , Fetal Macrosomia/epidemiology , Humans , Hyperlipidemias/complications , Infant, Newborn , Malaysia/epidemiology , Male , Obesity/epidemiology , Pregnancy , Prospective Studies , Surveys and Questionnaires , Triglycerides/blood
5.
Diabet Med ; 35(8): 1118-1129, 2018 08.
Article in English | MEDLINE | ID: mdl-29663517

ABSTRACT

AIMS: To determine if therapeutic, retrospective continuous glucose monitoring (CGM) improves HbA1c with less hypoglycaemia in women with insulin-treated gestational diabetes mellitus (GDM). METHODS: This prospective, randomized controlled, open-label trial evaluated 50 women with insulin-treated GDM randomized to either retrospective CGM (6-day sensor) at 28, 32 and 36 weeks' gestation (Group 1, CGM, n = 25) or usual antenatal care without CGM (Group 2, control, n = 25). All women performed seven-point capillary blood glucose (CBG) profiles at least 3 days per week and recorded hypoglycaemic events (symptomatic and asymptomatic CBG < 3.5 mmol/l; non-fasting < 4.0 mmol/l). HbA1c was measured at 28, 33 and 37 weeks. In Group 1, both CGM and CBG data were used to manage diabetes, whereas mothers in Group 2 were managed based on CBG data alone. RESULTS: Baseline characteristics (age, pre-pregnancy BMI, HbA1c , total insulin dose) were similar between groups. There was a lower increase in HbA1c from 28 to 37 weeks' gestation in the CGM group [∆HbA1c : CGM + 1 mmol/mol (0.09%), control + 3mmol/mol (0.30%); P = 0.024]. Mean HbA1c remained unchanged throughout the trial in the CGM group, but increased significantly in controls as pregnancy advanced. Mean HbA1c in the CGM group was lower at 37 weeks compared with controls [33 ± 4 mmol/mol (5.2 ± 0.4%) vs. 38 ± 7 mmol/mol (5.6 ± 0.6%), P < 0.006]. Some 92% of the CGM group achieved an HbA1c ≤ 39 mmol/mol (≤ 5.8%) at 37 weeks compared with 68% of the control group (P = 0.012). Neither group experienced severe hypoglycaemia. CONCLUSION: CGM use may be beneficial in insulin-treated GDM because it improves HbA1c compared with usual antenatal care without increasing severe hypoglycaemia. (Clinical Trials Registry No.: NCT02204657).


Subject(s)
Blood Glucose/analysis , Diabetes, Gestational/blood , Diabetes, Gestational/drug therapy , Glycated Hemoglobin/metabolism , Insulin/therapeutic use , Adult , Blood Glucose/drug effects , Blood Glucose/metabolism , Blood Glucose Self-Monitoring/instrumentation , Blood Glucose Self-Monitoring/methods , Female , Glycated Hemoglobin/analysis , Glycated Hemoglobin/drug effects , Humans , Malaysia , Pregnancy , Prenatal Care/methods , Standard of Care
6.
Trop Biomed ; 33(4): 746-752, 2016 Dec 01.
Article in English | MEDLINE | ID: mdl-33579071

ABSTRACT

Dengue infection is endemic in South East Asia and parts of the Americas. Dengue hemorrhagic fever is characterized by vascular permeability, coagulation-disorders and thrombocytopenia, which can culminate in hypotension i.e. dengue shock syndrome. Hypopituitarism arising as a complication of dengue is extremely rare. Hemorrhagic pituitary apoplexy of pre-existing pituitary adenomas has been rarely reported in dengue. We describe an uncommon case of hypopituitarism in a dengue shock syndrome survivor without known pituitary adenoma. A 49 years old nulliparous lady (from Kuala Lumpur, Malaysia) presented with typical symptoms of hypocortisolism. Postural hypotension was evident with normal secondary sexual characteristics. Further history revealed that she survived an episode of dengue shock syndrome 6 years ago where premature menopause developed immediately after discharge, and subsequently insidious onset of multiple hormonal deficiencies indicative of panhypopituitarism. There were no neuro-ophthalmological symptoms suggestive of pituitary apoplexy during hospitalization for severe dengue. Magnetic resonance imaging of the pituitary 6 years later revealed an empty sella. Autoimmune screen and anti-thyroid peroxidase antibodies were negative. We describe a rare possible causative association of severe dengue with panhypopituitarism without known pituitary adenoma, postulating pituitary infarction secondary to hypotension (mimicking Sheehan's syndrome), or a direct viral cytopathic effect. Subclinical pituitary apoplexy secondary to asymptomatic pituitary hemorrhage however cannot be excluded. Future research is required to determine the need for and timing of pituitary axis assessment among dengue shock syndrome survivors.

7.
Tropical Biomedicine ; : 746-752, 2016.
Article in English | WPRIM (Western Pacific) | ID: wpr-630854

ABSTRACT

Dengue infection is endemic in South East Asia and parts of the Americas. Dengue hemorrhagic fever is characterized by vascular permeability, coagulation-disorders and thrombocytopenia, which can culminate in hypotension i.e. dengue shock syndrome. Hypopituitarism arising as a complication of dengue is extremely rare. Hemorrhagic pituitary apoplexy of pre-existing pituitary adenomas has been rarely reported in dengue. We describe an uncommon case of hypopituitarism in a dengue shock syndrome survivor without known pituitary adenoma. A 49 years old nulliparous lady (from Kuala Lumpur, Malaysia) presented with typical symptoms of hypocortisolism. Postural hypotension was evident with normal secondary sexual characteristics. Further history revealed that she survived an episode of dengue shock syndrome 6 years ago where premature menopause developed immediately after discharge, and subsequently insidious onset of multiple hormonal deficiencies indicative of panhypopituitarism. There were no neuro-ophthalmological symptoms suggestive of pituitary apoplexy during hospitalization for severe dengue. Magnetic resonance imaging of the pituitary 6 years later revealed an empty sella. Autoimmune screen and anti-thyroid peroxidase antibodies were negative. We describe a rare possible causative association of severe dengue with panhypopituitarism without known pituitary adenoma, postulating pituitary infarction secondary to hypotension (mimicking Sheehan’s syndrome), or a direct viral cytopathic effect. Subclinical pituitary apoplexy secondary to asymptomatic pituitary hemorrhage however cannot be excluded. Future research is required to determine the need for and timing of pituitary axis assessment among dengue shock syndrome survivors.

8.
Pituitary ; 18(4): 448-55, 2015 Aug.
Article in English | MEDLINE | ID: mdl-25134488

ABSTRACT

PURPOSE: Radiation fields for nasopharyngeal cancer (NPC) include the base of skull, which places the hypothalamus and pituitary at risk of damage. We aimed to establish the prevalence, pattern and severity of hypothalamic pituitary (HP) dysfunction amongst NPC survivors. METHODS: We studied 50 patients (31 males) with mean age 57 ± 12.2 years who had treatment for NPC between 3 and 21 years (median 8 years) without pre-existing HP disorder from other causes. All patients had a baseline cortisol, fT4, TSH, LH, FSH, oestradiol/testosterone, prolactin and renal function. All patients underwent dynamic testing with insulin tolerance test to assess the somatotroph and corticotroph axes. Baseline blood measurements were used to assess thyrotroph, gonadotroph and lactotroph function. RESULTS: Hypopituitarism was present in 82% of patients, 30% single axis, 28% two axes, 18% three axes and 6% four axes deficiencies. Somatotroph deficiency was most common (78%) while corticotroph, gonadotroph and thyrotroph deficiencies were noted in 40% (4 complete/16 partial), 22 and 4% of the patients respectively. Hyperprolactinaemia was present in 30% of patients. The development of HP dysfunction was significantly associated with the time elapsed from irradiation, OR 2.5 (1.2, 5.3), p = 0.02, for every 2 years post treatment. The use of concurrent chemo-irradiation (CCRT) compared to those who had radiotherapy alone was also significantly associated with HP dysfunction, OR 14.5 (2.4, 87.7), p < 0.01. CONCLUSION: Despite low awareness and detection rates, HP dysfunction post-NPC irradiation is common. Use of CCRT may augment time related pituitary damage. As these endocrinopathies result in significant morbidity and mortality we recommend periodic assessment of pituitary function amongst NPC survivors.


Subject(s)
Human Growth Hormone/deficiency , Hyperprolactinemia/epidemiology , Hypopituitarism/epidemiology , Hypothalamo-Hypophyseal System , Nasopharyngeal Neoplasms/therapy , Survivors , Aged , Chemoradiotherapy , Cross-Sectional Studies , Estradiol/blood , Female , Follicle Stimulating Hormone/blood , Humans , Hydrocortisone/blood , Hyperprolactinemia/blood , Hypogonadism/blood , Hypogonadism/epidemiology , Hypopituitarism/blood , Hypothyroidism/blood , Hypothyroidism/epidemiology , Luteinizing Hormone/blood , Male , Middle Aged , Organs at Risk , Prolactin/blood , Radiotherapy , Testosterone/blood , Thyrotropin/blood , Thyroxine/blood
9.
J Clin Pediatr Dent ; 39(1): 12-7, 2014.
Article in English | MEDLINE | ID: mdl-25631719

ABSTRACT

OBJECTIVES: We evaluated the relationship between child dental anxiety and selected child and parental characteristics. STUDY DESIGN: Children and their parents were interviewed at the New York University, College of Dentistry, Pediatric Dentistry Clinic. The Children's Fear Survey Schedule - Dental Subscale (CFSS-DS) evaluated child self-reported anxiety; the Modified Dental Anxiety Scale (MDAS) measured self-reported parental anxiety when the parent received dental treatment. RESULTS: Ninety-three children and their parents completed the questionnaires. Mean CFSS-DS scores were higher for girls than boys (32.5 vs. 26.3, p=0.003) and for children whose accompanying parents had MDAS scores of 11+ vs. ≥ 11 (32.8 vs. 26.6, p=0.001). There was little difference in mean CFSS-DS scores among those aged 6-10 yrs. vs. 11-14 yrs. (30.1 vs. 29.3). Significant correlations were found between CFSS-DS and both gender (Spearman's rho, rs=0.31) and MDAS scores (rs=0.33), but not between CFSS-DS and child age (rs=-0.05). Controlling simultaneously for gender, MDAS score and child age, a high CFSS-DS score (38+ vs. ≥ 38) was positively associated with girls (ORadj=3.76, 95% CI: 1.13-12.54) and an MDAS score of ≤ 15 vs. ≥ 11 (ORadj=2.50, 0.73-8.54), but weakly and inversely associated with age (ORadj=0.80, 0.25-2.52). CONCLUSION: Child gender and parental anxiety are indicators of child dental anxiety.


Subject(s)
Dental Anxiety/diagnosis , Dental Care for Children/psychology , Adolescent , Age Factors , Child , Dental Anxiety/psychology , Female , Humans , Injections/psychology , Male , Parent-Child Relations , Parents/psychology , Self Report , Sex Factors , Stress, Psychological/psychology , Surveys and Questionnaires
11.
Clin Genet ; 82(6): 564-8, 2012 Dec.
Article in English | MEDLINE | ID: mdl-22233476

ABSTRACT

Li-Fraumeni syndrome (LFS) is a highly penetrant, autosomal dominant disorder where affected individuals carry a 50% risk of developing cancer before 30 years of age. It is most commonly associated with mutations in the tumour suppressor gene, TP53. Adrenocortical carcinoma (ACC) is a very rare paediatric cancer, and up to 80% of affected children are found to carry germline TP53 mutations. Hence, we propose using childhood ACC incidence as selection criteria for referral for TP53 mutation testing, independent of familial cancer history. Under the auspices of the Malaysian Society of Paediatric Haematology-Oncology, four eligible children diagnosed with ACC over a 30-month study period were referred for mutation testing. Three had a germline TP53 mutation. Subsequent TP53 testing in relatives showed two inherited mutations and one de novo mutation. These findings strongly support paediatric ACC as a useful sentinel cancer for initiating a germline TP53/LFS detection programme, particularly in countries where the lack of structured oncogenetic practice precludes the identification of families with LFS features.


Subject(s)
Adrenocortical Carcinoma/pathology , Genetic Testing/methods , Germ-Line Mutation/genetics , Li-Fraumeni Syndrome/diagnosis , Tumor Suppressor Protein p53/genetics , Adrenocortical Carcinoma/genetics , Child , DNA Mutational Analysis , Genetic Testing/standards , Humans , Li-Fraumeni Syndrome/genetics , Malaysia , Pedigree , Sentinel Surveillance
12.
Nutr Metab Cardiovasc Dis ; 22(1): 42-9, 2012 Jan.
Article in English | MEDLINE | ID: mdl-20674301

ABSTRACT

BACKGROUND AND AIMS: Waist circumference (WC), waist-to-hip ratio (WHR) and waist-to-stature ratio (WSR), being common proxy measures of abdominal obesity, are useful tools in epidemiologic studies, but little is known about their validity when the indices are derived from self-reported measurements. We determine and compare the validity of self-reported WC, WHR and WSR in order to identify the optimal index for use in epidemiologic surveys. METHODS AND RESULTS: Technician- and self-reported measurements of height, waist and hip circumference were obtained from 613 Thai adults (mean age 35 years). Regarding technician-reported measurements as reference, diagnostic test properties were derived and performances of the indices compared using receiver-operator-characteristic curves and the area-under-the-curve (AUC) analyses. There was good agreement between technician- and self-reported measurements for WC and WSR (concordance correlation coefficients ranged from 0.84 to 0.90) but not for WHR (0.50 in men, 0.45 in women). The sensitivity and specificity of self-reported WC and self-reported WSR as measures of abdominal obesity were superior to those of self-reported WHR in both sexes. AUCs for WC and WSR were comparable (0.93 and 0.92, respectively, in men; 0.88 and 0.87 in women) and significantly higher than for WHR (0.80 in men; 0.76 in women; p<0.0001). CONCLUSION: WC and WSR derived from self-reported waist and height measurements are valid methods for determining abdominal obesity. Self-reported measurements should not be used to derive the WHR. In Asian populations, WSR may be the optimal index of abdominal obesity when measurements are derived from self-reports in epidemiologic surveys.


Subject(s)
Body Height , Obesity, Abdominal/epidemiology , Waist Circumference , Waist-Hip Ratio , Adult , Asian People , Body Composition , Body Mass Index , Epidemiologic Studies , Female , Humans , Male , Middle Aged , Obesity, Abdominal/diagnosis , ROC Curve , Reproducibility of Results , Self Report , Sensitivity and Specificity , Surveys and Questionnaires , Thailand/epidemiology , Young Adult
13.
J Hazard Mater ; 194: 100-8, 2011 Oct 30.
Article in English | MEDLINE | ID: mdl-21890266

ABSTRACT

Remediation of groundwater contaminated by gasoline leakage from underground structures is usually complicated and costly. This work describes the use of an underground reactor, in a sand tank, placed downgradient from a simulated leakage of MTBE and other gasoline components. The reactor, Honeycomb I, is full scale in the horizontal plane. It tested the remediation of MTBE plumes at various velocities and in the presence of other gasoline compounds (toluene, ethylbenzene and o-xylene - TEo-X). The overall performance of Honeycomb I was evaluated and the efficiencies of two different experimental scales were compared. The MTBE plume was longer but narrower with increasing groundwater to MTBE velocity ratio. MTBE appeared to have a minor co-solvent effect on the TEo-X migration as TEo-X migrated at the MTBE migration rate but at significantly low concentrations. The MTBE removal efficiency decreased by about 8% in the presence of TEo-X. The scaled up Honeycomb I successfully treated 212L of groundwater in 24 days and demonstrated its reliability over a 10-month period, achieving an overall 76% MTBE removal. In essence, this study demonstrated the potential of the immobilised photocatalytic reactor for in situ groundwater remediation, at the velocities tested in this study.


Subject(s)
Environmental Restoration and Remediation/methods , Groundwater/chemistry , Organic Chemicals/isolation & purification , Catalysis , Feasibility Studies , Photochemistry
14.
Endoscopy ; 43(4): 300-6, 2011 Apr.
Article in English | MEDLINE | ID: mdl-21360421

ABSTRACT

BACKGROUND AND STUDY AIMS: The role of urgent endoscopy in high-risk nonvariceal upper gastrointestinal bleeding (NVUGIB) is unclear. The aim of this study was to determine whether esophagogastroduodenoscopy (EGD) performed sooner than the currently recommended 24 h in high-risk patients presenting with NVUGIB is associated with lower all-cause in-hospital mortality. METHODS: All adult patients undergoing EGD for the indications of coffee-grounds vomitus, hematemesis or melena at a university hospital over an 18-month period were enrolled. Patients with variceal and lower gastrointestinal bleeding were excluded. Data were prospectively collected. RESULTS: A total of 934 patients were included. The area under the receiver operating characteristic curve (AUROC) for the Glasgow-Blatchford score (GBS) was 0.813 for predicting all-cause in-hospital mortality, with a cut-off score of ≥ 12 resulting in 90 % specificity. In low-risk patients with GBS < 12, presentation-to-endoscopy time in those who died and in those who survived was similar. In high-risk patients with GBS of ≥ 12, presentation-to-endoscopy time was significantly longer in those who died than in those who survived. Multivariate analysis of the high-risk cohort showed presentation-to-endoscopy time to be the only factor associated with all-cause in-hospital mortality. For high-risk patients, the AUROC for presentation-to-endoscopy time in predicting all-cause in-hospital mortality was 0.803, with a sensitivity of 100 % at the cut-off time of 13 h. All-cause in-hospital mortality in high-risk patients was significantly higher in those with presentation-to-endoscopy time of > 13 h compared with those undergoing endoscopy in < 13 h from presentation (44 % vs. 0 %; P < 0.001). CONCLUSIONS: Endoscopy within 13 h of presentation was associated with lower mortality in high-risk but not low-risk NVUGIB.


Subject(s)
Endoscopy, Gastrointestinal , Gastrointestinal Hemorrhage/mortality , Hemostasis, Endoscopic , Hospital Mortality , Acute Disease , Aged , Emergencies , Female , Gastrointestinal Hemorrhage/therapy , Humans , Male , Middle Aged , Risk Factors , Survival Analysis
15.
Soc Indic Res ; 98(2): 201-215, 2010 Sep.
Article in English | MEDLINE | ID: mdl-20835292

ABSTRACT

Satisfaction with life correlates with other measures of subjective wellbeing and correlates predictably with individual characteristics and overall health. Social indicators and subjective wellbeing measures are necessary to evaluate a society and can be used to produce national indicators of happiness. This study therefore aims to help close the gap in wellbeing data for Thailand. The specific aims are to: (1) calculate the Thai PWI and domain scores using a large scale sample; (2) examine the level of life satisfaction of Thais when compared to international standards; (3) examine the Thai PWI and domains in relation to demographic, socioeconomic, and geographic characteristics. Our report derives from the findings on the Personal Wellbeing Index (PWI) in a large national cohort of Sukhothai Thammathirat Open University adult students living all over Thailand (n = 87,134). This Thai cohort had an overall PWI of 70.0 on a scale from 0 to 100 which is consistent with Western populations. The 'spirituality and religion' domain had the highest average score. 'Standard of living', 'future security' and 'achievement in life' made the largest contribution to overall 'satisfaction in life as a whole'. These domains also show a positive trend with increasing age, being married, higher income, more education, more household assets, and rural residence. The PWI will be an important tool for policymakers to understand the subjective wellbeing of population groups especially as Thailand is undergoing a political and economic transition.

16.
Atmos Environ (1994) ; 44(37): 4678-4734, 2010 Dec.
Article in English | MEDLINE | ID: mdl-32288556

ABSTRACT

Aviation alters the composition of the atmosphere globally and can thus drive climate change and ozone depletion. The last major international assessment of these impacts was made by the Intergovernmental Panel on Climate Change (IPCC) in 1999. Here, a comprehensive updated assessment of aviation is provided. Scientific advances since the 1999 assessment have reduced key uncertainties, sharpening the quantitative evaluation, yet the basic conclusions remain the same. The climate impact of aviation is driven by long-term impacts from CO2 emissions and shorter-term impacts from non-CO2 emissions and effects, which include the emissions of water vapour, particles and nitrogen oxides (NO x ). The present-day radiative forcing from aviation (2005) is estimated to be 55 mW m-2 (excluding cirrus cloud enhancement), which represents some 3.5% (range 1.3-10%, 90% likelihood range) of current anthropogenic forcing, or 78 mW m-2 including cirrus cloud enhancement, representing 4.9% of current forcing (range 2-14%, 90% likelihood range). According to two SRES-compatible scenarios, future forcings may increase by factors of 3-4 over 2000 levels, in 2050. The effects of aviation emissions of CO2 on global mean surface temperature last for many hundreds of years (in common with other sources), whilst its non-CO2 effects on temperature last for decades. Much progress has been made in the last ten years on characterizing emissions, although major uncertainties remain over the nature of particles. Emissions of NO x result in production of ozone, a climate warming gas, and the reduction of ambient methane (a cooling effect) although the overall balance is warming, based upon current understanding. These NO x emissions from current subsonic aviation do not appear to deplete stratospheric ozone. Despite the progress made on modelling aviation's impacts on tropospheric chemistry, there remains a significant spread in model results. The knowledge of aviation's impacts on cloudiness has also improved: a limited number of studies have demonstrated an increase in cirrus cloud attributable to aviation although the magnitude varies: however, these trend analyses may be impacted by satellite artefacts. The effect of aviation particles on clouds (with and without contrails) may give rise to either a positive forcing or a negative forcing: the modelling and the underlying processes are highly uncertain, although the overall effect of contrails and enhanced cloudiness is considered to be a positive forcing and could be substantial, compared with other effects. The debate over quantification of aviation impacts has also progressed towards studying potential mitigation and the technological and atmospheric tradeoffs. Current studies are still relatively immature and more work is required to determine optimal technological development paths, which is an aspect that atmospheric science has much to contribute. In terms of alternative fuels, liquid hydrogen represents a possibility and may reduce some of aviation's impacts on climate if the fuel is produced in a carbon-neutral way: such fuel is unlikely to be utilized until a 'hydrogen economy' develops. The introduction of biofuels as a means of reducing CO2 impacts represents a future possibility. However, even over and above land-use concerns and greenhouse gas budget issues, aviation fuels require strict adherence to safety standards and thus require extra processing compared with biofuels destined for other sectors, where the uptake of such fuel may be more beneficial in the first instance.

17.
Singapore Med J ; 50(4): 365-70, 2009 Apr.
Article in English | MEDLINE | ID: mdl-19421679

ABSTRACT

INTRODUCTION: Recombinant erythropoietin-stimulating agents have been used to ameliorate the symptoms of anaemia in cancer patients. However, there have been concerns about an increased risk of thromboembolic events and mortality. This study reviews the usage of epoetin alfa in treating chemotherapy-induced anaemia at the National Cancer Centre Singapore (NCCS), as well as the prescribing and monitoring practices employed. METHODS: Cancer patients who have received at least one dose of epoetin alfa at the NCCS between January 1, 2005 and October 15, 2007 were included in this study. RESULTS: A total of 121 patients were identified and 91 patients were eligible for data collection. The majority of patients manifested breast cancer (30.8 percent) and ovarian cancer (15.4 percent). Over 90 percent of the patients were receiving either chemotherapy or radiotherapy when epoetin alfa was initiated. Epoetin alfa was initiated at a median haemoglobin level of 8.7 (range 7-14.3) g/dL. Approximately 41.8 percent of the patients had a positive response after the initiation of epoetin alfa. Baseline iron studies were performed in 12.1 percent of the patients. Blood pressure was uncontrolled, according to the Singapore Ministry of Health Hypertension guideline, in a substantial number of patients (32.6 percent) prior to the initiation epoetin alfa. There were no documented thromboembolic events. CONCLUSION: This study identified a broad range of practices in the utilisation of epoetin alfa at NCCS, which may explain the variable patient response to epoetin alfa. The results of this study will be used to improve the management of chemotherapy-induced anaemia at the institution.


Subject(s)
Anemia/chemically induced , Anemia/drug therapy , Antineoplastic Agents/adverse effects , Erythropoietin/therapeutic use , Hematinics/therapeutic use , Neoplasms/drug therapy , Adolescent , Adult , Aged , Aged, 80 and over , Anemia/blood , Antineoplastic Agents/therapeutic use , Blood Cell Count , Blood Pressure/drug effects , Blood Transfusion , Cancer Care Facilities/statistics & numerical data , Dose-Response Relationship, Drug , Drug Administration Schedule , Epoetin Alfa , Female , Hemoglobinometry , Humans , Male , Middle Aged , Neoplasms/blood , Recombinant Proteins , Retrospective Studies , Singapore , Utilization Review/statistics & numerical data , Young Adult
18.
Colorectal Dis ; 11(9): 984-5, 2009 Nov.
Article in English | MEDLINE | ID: mdl-19175636

ABSTRACT

Mr C, a 68-year-old Chinese male with diabetes mellitus, previous stroke and ischaemic cardiomyopathy on clopidogrel, presented with haematochezia. Colonoscopy showed a sigmoid ulcer, which was treated endoscopically. Histology of the biopsy from the ulcer revealed non-specific changes. However, he presented with recurrent bleeding from this non-healing sigmoid ulcer. A review of the histologic specimen revealed CMV intranuclear inclusion bodies. He was treated with intravenous ganciclovir, with no further hematochezia.


Subject(s)
Cytomegalovirus Infections/diagnosis , Cytomegalovirus Infections/pathology , Gastrointestinal Hemorrhage/virology , Sigmoid Diseases/virology , Ulcer/virology , Aged , Antiviral Agents , Biopsy , Cytomegalovirus Infections/drug therapy , Ganciclovir/therapeutic use , Humans , Immunocompetence , Male
19.
Br J Ophthalmol ; 92(10): 1316-9, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18684751

ABSTRACT

AIM: To describe the prevalence and risk factors of retinal vein occlusion (RVO) in an Asian population. METHODS: The Singapore Malay Eye Study is a population-based, cross-sectional study of 3280 (78.7%) Malay adults (aged 40-80 years) living in Singapore. All participants underwent retinal photography, standardised interview, clinical examinations and laboratory investigations. RVO (central or branch) was graded based on the Blue Mountains Eye Study (BMES) protocol from retinal photographs. RESULTS: The overall prevalence of RVO was 0.7% (n = 22) (95% CI 0.4 to 1.0) (18 branch and five central RVO cases). There was no significant gender difference in RVO prevalence. RVO was associated with higher systolic blood pressure (age-adjusted odds ratio (OR) per SD increase 1.54, CI 1.02 to 2.31), ocular perfusion pressure (OR per SD increase 1.49, CI 1.03 to 2.16), a history of angina (OR 5.18, CI 1.49 to 18.0) and heart attack (OR 4.26, CI 1.47 to 12.3), and higher total cholesterol (OR per SD increase 1.55, CI 1.07 to 2.24) and LDL (OR per SD increase 1.47, CI 1.02 to 2.12) cholesterol levels. CONCLUSIONS: The prevalence of RVO in this Asian population was lower than Caucasians in the BMES, although the systemic associations of RVO were largely similar to BMES and other studies.


Subject(s)
Cardiovascular Diseases/complications , Retinal Vein Occlusion/ethnology , Adult , Aged , Aged, 80 and over , Asian People/ethnology , Cardiovascular Diseases/ethnology , Cross-Sectional Studies , Female , Humans , Hypercholesterolemia/ethnology , Intraocular Pressure , Male , Middle Aged , Prevalence , Retinal Vein Occlusion/diagnosis , Risk Factors , Singapore/ethnology
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