Body mass index and smoking-related lung cancer risk in the Singapore Chinese Health Study.

BACKGROUND: Smokers with low body mass index (BMI) may be more susceptible to lung cancer. METHODS: We prospectively examined the association between baseline BMI and lung cancer risk in the Singapore Chinese Health Study, a cohort of 63 257 Chinese enrolled between 1993 and 1998. RESULTS: After adjustment for smoking intensity and duration, BMI was inversely associated with risk of lung cancer among current smokers (P for trend=0.0004). Current smokers at different dosage of smoking with low BMI had significantly higher risk for lung cancer than those with high BMI. Hazard ratios (95% confidence intervals) of lung cancer for heavy smokers with BMI of > or =28, 24-<28, 20-<24, and <20 kg m(-2) were 6.37 (2.10-19.30), 9.01 (5.04-16.10), 8.53 (6.35-11.5), and 11.12 (6.60-18.70), respectively, as compared with nonsmokers. BMI had no modifying effects on lung cancer risk among nonsmokers and former smokers. CONCLUSION: Smokers with lower BMI may experience an enhanced risk of lung cancer. The findings have significant public-health implication given the increase in smoking prevalence in developing countries, where people still have relatively low BMI.

Smoking cessation and lung cancer risk in an Asian population: findings from the Singapore Chinese Health Study.

BACKGROUND: Smoking cessation is an important strategy for reducing the harmful effects of tobacco, particularly in the prevention of lung cancer; however, prospective data on the impact of smoking cessation on lung cancer risk in Asian populations are limited. METHODS: We studied a population-based cohort of Chinese men and women aged 45-74 years--participants of the Singapore Chinese Health Study. Information on smoking, lifestyle and dietary habits was collected at the time of recruitment in 1993-1998; and smoking status was assessed again at a second interview in 1999-2004 (mean interval 5.8 years). Participants were followed up to 31 December 2007, and incident cases of lung cancer were ascertained by linkage with population-wide registries. RESULTS: Among 45,900 participants, there were 463 incident cases of lung cancer. Relative to current smokers, those who quit smoking subsequent to baseline assessment had a 28% decrease in the risk of lung cancer (adjusted hazard ratio (HR) 0.72; 95% CI (95% confidence interval): 0.53-0.98). The risk was less than half in ex-smokers who had quit before the first interview and maintained their status (HR 0.42; 95% CI: 0.32-0.56). CONCLUSIONS: Reduction in lung cancer incidence with smoking cessation in Asian populations is substantial and can be observed within a few years after quitting.

A review of the implications of computational fluid dynamic studies on nasal airflow and physiology.

BACKGROUND: Computational fluid dynamics has been adapted to studying nasal aerodynamics. AIM: To review current literature on CFD studies, with an emphasis on normal nasal airflow, the impact of sinonasal pathology on airflow, and implications on nasal physiology. The objective is to provide the rhinologists with a greater understanding of nasal airflow and how symptomatology of sinonasal disease may be explained via CFD simulations. RESULTS: The nasal valve region redirects inspiratory airstreams over the inferior turbinate in a high turbulent kinetic energy, which is important in heat and moisture exchange. The bulk of airflow occurs in the common meatus with small streams traversing the olfactory groove, increasing during sniffing. Septal deviation and enlarged inferior turbinate causes redistribution of airflow, changes in intranasal pressure and increased turbulence. High velocity airflow and wall shear stress at the septal perforation causes desiccation and mucosal damage. The airflow within an atrophic nasal cavity is predominantly laminar with minimal contact with nasal mucosa. The inferior turbinate is an important organ for air conditioning and preservation during surgery is highlighted. CONCLUSIONS: Despite some limitations of CFD simulations, this technology has improved understanding of the complex nasal anatomy and the implications of disease and surgery on physiology.

Aerodynamic effects of inferior turbinate surgery on nasal airflow--a computational fluid dynamics model.

BACKGROUND: Turbinate reduction surgery may be indicated for inferior turbinate enlargement when conservative treatment fails. The aim of this study was to evaluate the effects of inferior turbinate surgery on nasal aerodynamics using computational fluid dynamics (CFD) simulations. METHODS: CFD simulations were performed for the normal nose, enlarged inferior turbinate and following three surgical procedures: (1) resection of the lower third free edge of the inferior turbinate, (2) excision of the head of the inferior turbinate and (3) radical inferior turbinate resection. The models were constructed from MRI scans of a healthy human subject and a turbulent flow model was used for the numerical simulation. The consequences of the three turbinate surgeries were compared with originally healthy nasal model as well as the one with severe nasal obstruction. RESULTS: In the normal nose, the bulk of streamlines traversed the common meatus adjacent to the inferior and middle turbinate in a relatively vortex free flow. When the inferior turbinate was enlarged, the streamlines were directed superiorly at higher velocity and increased wall shear stress in the nasopharynx. Of the three surgical techniques simulated, wall shear stress and intranasal pressures achieved near-normal levels after resection of the lower third. In addition, airflow streamlines and turbulence improved although it did not return to normal conditions. As expected, radical turbinate resection resulted in intra-nasal aerodynamics of atrophic rhinitis demonstrated in previous CFD studies. CONCLUSION: There is little evidence that inspired air is appropriately conditioned following radical turbinate surgery. Partial reduction of the hypertropic turbinate results in improved nasal aerodynamics, which was most evident following resection of the lower third. The results were based on a single individual and cannot be generalised without similar studies in other subjects.

Community psycho-behavioural surveillance and related impact on outbreak control in Hong Kong and Singapore during the SARS epidemic.

1. The promotion of personal protective health practices must take into account background perceptions of risk and psychological responses in the community-at-large. 2. Population psycho-behavioural factors in Hong Kong and Singapore are shown to be an important potential vector for the transmission of an infectious agent. 3. Comparative psycho-behavioural surveillance and analysis can yield important insights into generic versus population-specific issues that could be used to inform, design and benchmark public health infection control measures.

Soy intake and breast cancer risk in Singapore Chinese Health Study.

We investigated the effects of soy isoflavone intake on breast cancer in a prospective study of 35,303 Singapore Chinese women enrolled during April 1993 to December 1998 in the Singapore Chinese Health Study. At recruitment, each subject was personally administered a validated semiquantitative food frequency questionnaire covering 165 food and beverage items. As of December 31,2005, 629 had developed breast cancer following an accumulation of 338,242 person-years. Using Cox regression and adjusting for age at interview, year of interview, dialect group, education, family history of breast cancer, age when periods became regular, parity, menopausal status, body mass index (BMI), n-3 fatty acid, and other covariates, we found breast cancer risk was reduced significantly in association with high soy intake. Relative to women with lower (below median) soy intake (<10.6 mg isoflavone per 1000 Kcal), women with higher (above median) intake showed a significant 18% risk reduction (relative risk (RR)=0.82, 95% confidence interval (CI)=0.70-0.97). This inverse association was apparent mainly in postmenopausal women (RR=0.74, 95% CI=0.61-0.90), and was not observed in premenopausal women (RR=1.04, 95% CI=0.77-1. 40). Among postmenopausal women, the soy-breast cancer association was stronger in those above median BMI (RR=0.67, 95% CI=0.51-0.88) than in leaner women (RR=0.83, 95% CI=0.62-1.11). Duration of follow-up modified the soy-breast cancer association, the effect being twice as large among women with 10+ vs fewer years of follow-up. Neither oestrogen nor progesterone receptor status of the tumours materially influenced the association. These prospective findings suggest that approximately 10 mg of isoflavones per day, obtained in a standard serving of tofu, may have lasting beneficial effects against breast cancer development.

Association of cyclin D1 G870A polymorphism with uterine leiomyoma in women whose body mass index values are above 25 kg/m2.

BACKGROUND: Many studies have shown that a polymorphism (G870A) in cyclin D1 (CCND1) is associated with carcinogenesis in a variety of cancers. Our aim was to determine if an association exists between the CCND1 G870A polymorphism and uterine leiomyoma in Korean women. METHODS: Blood samples of 331 cases and 204 controls aged 47.4 +/- 7.6 and 46.8 +/- 10.4 years (mean +/- SD), respectively, were collected. CCND1 genotyping was determined by PCR and restriction fragment length polymorphism. RESULTS: Allelic frequencies of cases (A, 0.53; G, 0.47) were not significantly different from those of controls (A, 0.49; G, 0.51) (P = 0.22). After adjustment for menarche age and BMI, multivariate logistic regression analysis showed that the AA genotype was not associated with increased risk for uterine leiomyoma [odds ratio (OR) = 1.38, 95% confidence interval (CI); 0.85-2.26, P = 0.19]. However, in stratification analysis of cases and controls with BMI >25 kg/m(2), allelic frequencies of cases (A, 0.56; G, 0.44) were significantly different from controls (A, 0.36; G, 0.64) (P = 0.005), and the AA genotype was associated with increased risk for uterine leiomyoma (OR = 3.61, 95% CI; 1.02-12.73, P = 0.046). Furthermore, the OR for AA compared with combined GG and AG genotypes was 3.16 (95% CI 1.01-9.92, P = 0.048). CONCLUSIONS: The A allele and AA genotype of CCND1 G870A polymorphism have a significant association with an increased risk of the uterine leiomyoma in obese Korean women.

Validation of the International Classification of Functioning, Disability, and Health (ICF) Brief Core Set for osteoarthritis.

OBJECTIVE: To validate the International Classification of Functioning, Disability, and Health (ICF) Brief Core Set for osteoarthritis (OA) by comparing the preliminary Brief Core Set to a selection of categories from the Comprehensive Core Set that explain most of the variance of functioning and health. METHODS: Patients with knee OA were asked to complete the Case Report Form for Patients, which includes the 36-item Short Form Health Survey (SF-36) and the Self-administered Comorbidity Questionnaire (SCQ). For each patient, the research staff was asked to complete the Case Report Form for Health Professionals, which includes the ICF Comprehensive Core Set for OA. Two individual questions regarding patients' general health and functioning were completed by both the patients and the research staff. The ICF categories to be entered into an initial regression model were selected following systematic steps in accordance with the ICF structure. Based on the initial models, additional models were generated by systematically substituting the ICF categories included in the initial models with other highly intercorrelated categories. RESULTS: A consecutive sample of 122 patients completed this study. Sixteen candidate ICF categories were identified by 15 linear regression models, which accounted for 5.5-57.7% of the total variance. Besides the two categories, b710 and b730, that are already included in the preliminary Brief Core Set, 14 additional categories were identified to be potential candidates for the Core Set. CONCLUSIONS: This study complemented the development of the Brief Core Set, which should be further refined by incorporating the opinions of patients, clinicians, and statisticians.

Characteristics of recurrence in adult-type granulosa cell tumor.

Granulosa cell tumor (GCT) of the ovary is a very rare neoplasm, which is characterized by an indolent clinical course. Thus, the clinical characteristics, optimal treatment, and follow-up protocols are not well established. The goal of this study is to evaluate clinical findings, prognostic factors, and recurrent features of GCT in Korean patients. Between 1987 and 2005, 42 cases of GCT were diagnosed in our institution. There were 35 cases showing adult-type GCT, which were available for evaluation. All charts were reviewed, and the clinical data along with treatment results were retrospectively studied. Statistical analyses were performed for risk factors of recurrence and disease-free survival. GCT accounted for 3% of all ovarian malignancies in our institution during the study period. The median age was 45 years (range, 24-68 years). Abdominal and hormone-related symptoms were the main causes of first presentation. There were eight cases of recurrence including two cases of disease-related deaths during the median follow-up period of 177 months (range, 8-212 months). Factors affecting the recurrence involved residual tumor and stage, but residual tumor was the only significant factor of recurrence in multivariate analysis. The median time to relapse was 75 months (range, 55-137 months), and the liver was the most common extra-pelvic metastatic site followed by the intestine. Continuous long-term follow-up with pelvic and whole-abdominal surveillance is absolutely required. Active management including complete tumorectomy is the most important treatment modality in both primary surgeries and recurrent cases.

Distribution and uptake of 137Cs in relation to alkali metals in a perhumid montane forest ecosystem.

We determined the content of radiocesium ((137)Cs) and alkali metals in soils, plants (2 ferns, a shrub and moss) and rainwater collected in an undisturbed forest ecosystem. The (137)Cs activity and the isotopic ratio of (137)Cs/Cs in the samples were used to interpret the distribution and uptake of (137)Cs and the alkali metals in plants. As a whole, the (137)Cs in plants was assimilated together with K but was not dependent on Cs. Different adaptations of fern species collected in ecological niches cause them to have different (137)Cs/Cs ratios. Diplopterygium glaucum is distributed at the edges of the forest; it usually has shallow organic layers, and the root takes up more stable Cs from mineral layers, leading to lower (137)Cs/Cs ratios than that in the understory Plagiogyria formosana and Rhododendron formosanum species. The steady supply of stable Cs through the uptake by D. glaucum from deep soils may gradually dilute the (137)Cs concentration and thus explain the lower (137)Cs/Cs ratio in the fern samples. The (137)Cs is predicted to be proportional to the Cs content across plant species in the biological cycle once isotopic equilibrium is attained.

Thermal-mechanical study of functionally graded dental implants with the finite element method.

This article investigates the thermal-mechanical performance of hydroxyapatite/titanium (HA/Ti) functionally graded (FG) dental implants with the three-dimensional finite element method. The stresses induced by occlusal force for the present HA/Ti FG implant are calculated to compare with the corresponding stresses for the titanium dental implant. Thermal-mechanical effect of temperature variation due to daily oral activity is also studied. The HA/Ti FG dental implant performance is evaluated against the maximum von Mises stress, which is the general performance indicator, the first principal/tensile stress for mechanical failure of implant-bone-bond and the third principal/compressive stress for bone absorption. Simulation results indicate that under the influence of occlusal force only, the FG implants with different HA fraction along the implant length perform almost equally well, while the titanium implant sustains much higher von Mises stress. However, when thermal stress is also considered, the FG implant having HA fraction exponential index of m = 2 with temperature decrease of 20 degrees C yields the highest first principal and von Mises stresses among all the FG and titanium implants.

Snoring source identification and snoring noise prediction.

This paper investigates the snoring mechanism of humans by applying the concept of structural intensity to a three-dimensional (3D) finite element model of a human head, which includes: the upper part of the head, neck, soft palate, hard palate, tongue, nasal cavity and the surrounding walls of the pharynx. Results show that for 20, 40 and 60Hz pressure loads, tissue vibration is mainly in the areas of the soft palate, the tongue and the nasal cavity. For predicting the snoring noise level, a 3D boundary element cavity model of the upper airway in the nasal cavity is generated. The snoring noise level is predicted for a prescribed airflow loading, and its range agrees with published measurements. These models may be further developed to study the various snoring mechanisms for different groups of patients.

Impact of diagnostic laparoscopy on the management of chronic pelvic pain.

BACKGROUND: Diagnostic laparoscopy is a useful tool, especially when there is no definite anatomical abnormality visible on imaging modalities. We assess the role and clinical impact of diagnostic laparoscopy in the management of women with chronic pelvic pain. METHODS: Clinical data of 3,068 cases of diagnostic laparoscopy performed for chronic pelvic pain from June 1994 to August 2005 were analyzed. We compared the diagnoses after diagnostic laparoscopy and those after pelvic examination and imaging modalities such as ultrasound or computed tomography (CT), and we then checked the final pathologic diagnoses after operation. RESULTS: Pelvic endometriosis was the most common (60.2%) laparoscopic finding in patients with chronic pelvic pain in this study, followed by normal pelvic findings (21.2%) and pelvic congestion (13.0%). Diagnostic laparoscopy had an influence on correcting previous plans based on imaging modalities in 42.7% of patients such as discarding unnecessary procedures or introducing new diagnostic or therapeutic plans. There were 3 cases of major complications requiring immediate correction. CONCLUSIONS: Diagnostic laparoscopy is a useful diagnostic tool for of women with chronic pelvic pain and can be used as a guideline for individualized treatment.

Molecular dynamics simulation of size and strain rate dependent mechanical response of FCC metallic nanowires.

Current computational simulations on metallic nanowires are largely focused on ultrathin wires with characteristic sizes smaller than 2 nm. The electronic, thermal and optical properties form the bulk of these studies, with investigations of the mechanical properties centred on the breaking force of monatomic chains, and the structural evolution of small nanowires subjected to axial, shear, bending and torsional forces. This study seeks to build on the wealth of current knowledge for computational simulation on the mechanical properties of metallic nanowires. The simulation scale will be upped to 24 000 atoms to study a larger metallic nanowire with a 6 nm characteristic size scale. The commonly studied Au nanowire is studied in conjunction with the rarely examined Pt nanowire. The effects that size and strain rate have on the stretching behaviour of these nanowires are investigated through the simulation of nanowires with three characteristic sizes of 2, 4 and 6 nm, subjected to three distinct strain rates of 4.0 x 10(8), 4.0 x 10(9) and 4.0 x 10(10) s(-1). The selected strain rates produce three distinct modes of deformation, namely crystalline-ordered deformation, mixed-mode deformation and amorphous-disordered deformation, respectively. The mechanisms behind the observations of these distinct deformation modes are analysed and explained. A Doppler 'red-shift' effect is observed when the nanowires are strained at the highest strain rate of 4.0 x 10(10) s(-1). This effect is most pronounced for the nanowire subjected to the largest stretch velocity. As a result, a constrained dynamic free-vibration phenomenon is observed during stretching, which eventually leads to delocalized multiple necking, instead of a single localized neck when it is strained at a lower rate. This unique phenomenon is discussed and future research effort is in the pipeline for a more detailed investigation into metallic nanowires strained at a supersonic velocity.

Cupping: from a biomechanical perspective.

The effectiveness of the cupping technique, a treatment modality in Traditional Chinese Medicine, in stimulating acupuncture points for pain relief was examined in this paper from a biomechanical perspective. Parametric studies including the effects of vacuum pressure, loading rate, friction coefficient at the cup-skin interface, and size and shape of the cup were carried out using a model based on the finite-element method. The anatomical structures of skin, fat, and muscle were modelled. All the soft-tissue layers were assumed to be nonlinearly elastic and viscoelastic. The rim of the cup was also modelled to study the interaction between cup and skin; the cup rim was assumed to be rigid. The simulation results showed that the stresses in the soft tissue were increased for increasing applied vacuum pressures and that the effects of cupping were mostly limited to the region enclosed by the cup. The simulations also indicated that the magnitude of the applied vacuum may have had direct implications for the severity of bruising of the skin following cupping treatment. Most significantly, the simulation results contradicted the established practice of cup size selection according to the depth of the disorder. Experimental verification of the proposed multi-layered finite-element model is presented. The nature of the bruising inherent to the cupping treatment is also explained by the proposed model.

A three-dimensional human head finite element model and power flow in a human head subject to impact loading.

A three-dimensional finite element model of the human head is presented. The model has been validated against two sets of experimental results. To assess injury likelihood of the head subjected to impact loading, the structural intensity (SI) methodology is introduced in accordance with the prevailing practice in experimental biomechanics. SI is a vector quantity indicating the direction and magnitude of power flow inside a dynamically loaded structure. In this paper, the SI field inside the head model is computed for three cases, namely frontal, rear and side impacts. The results for the three cases have revealed that there exist power flow paths. The skull is, in general, a good energy flow channel. The study has also revealed the high possibility of spinal cord injury due to wave motion inside the head.

Measurement of 224Ra uptake in a fern actively accumulating radium.

A method is proposed for determining the level of 224Ra in plant samples by measuring its descendant nuclide 212Pb at 239 keV by gamma-ray spectrometry. Variations of 224Ra and 212Pb over time during sample preparation and counting were delineated prior to gamma-ray measurement. The 224Ra concentrations in plant samples were measured by their direct uptake from soil, which could be determined and distinguished from that resulting from decay of 228Th inside the plants. We propose that a field-growing Dicranopteris linearis, which actively accumulates radium, can be used as an indicator of the nutritional transportation and metabolic rate of radium and other alkaline earth elements. We investigated the influence of rainfall on 224Ra concentrations in fronds of D. linearis and the corresponding uptake rates. 224Ra could serve as a natural tracer of growth in plants over a several days. Its presence and content in plants implies a temporal mineral metabolic rate, which can provide useful information for plant physiological and environmental investigations.

Parallel sequential minimal optimization for the training of support vector machines.

Sequential minimal optimization (SMO) is one popular algorithm for training support vector machine (SVM), but it still requires a large amount of computation time for solving large size problems. This paper proposes one parallel implementation of SMO for training SVM. The parallel SMO is developed using message passing interface (MPI). Specifically, the parallel SMO first partitions the entire training data set into smaller subsets and then simultaneously runs multiple CPU processors to deal with each of the partitioned data sets. Experiments show that there is great speedup on the adult data set and the Mixing National Institute of Standard and Technology (MNIST) data set when many processors are used. There are also satisfactory results on the Web data set.

Do urinary estrogen metabolites reflect the differences in breast cancer risk between Singapore Chinese and United States African-American and white women?

Breast cancer risk is substantially lower in Singapore than in women from the United STATES: Part of the risk discrepancy is probably explained by differences in the production of endogenous estrogens, but differences in the pathway by which estrogen is metabolized may also play a role. We undertook a study to determine whether the ratio of urinary 2-hydroxyestrone (2OHE(1)):16alpha-hydroxyestrone (16alpha-OHE(1)) was higher in Singapore Chinese than in a group of United States (predominantly African-American) women living in Los ANGELES: We also wanted to determine whether any difference in estrogen metabolite ratio between these two groups of women was greater than that in estrone (E(1)), estradiol (E(2)) and estriol (E(3)). The participants in this study were randomly selected healthy, non-estrogen using women participating in the Singapore Chinese Health Study (n = 67) or the Hawaii/Los Angeles Multiethnic Cohort Study (n = 58). After adjusting for age and age at menopause, mean urinary 2-OHE(1) was only 23% (P = 0.03) higher in Singapore Chinese than in United States women, and there were no statistically significant differences in 16alpha-OHE(1) levels or in the ratio of 2-OHE(1):16alpha-OHE(1) between the two groups. The adjusted mean 2-OHE(1):16alpha-OHE(1) ratio was 1.63 in Singapore Chinese and 1.48 in United States women (P = 0.41). In contrast, the adjusted mean values of E1, E2, and E3 were 162% (P < 0.0001), 152% (P < 0.0001), and 92% (P = 0.0009) higher, respectively, in United States women than in Singapore Chinese women. Our study suggests that urinary E1, E2, and E3 reflect the differences in breast cancer risk between Singapore Chinese and United States women to a stronger degree than the estrogen metabolites 2OHE(1) and 16alpha-OHE(1) or the ratio of 2OHE(1):16alpha-OHE(1.)

Investigation of AlGaN/GaN high electron mobility transistor structures on 200-mm silicon (111) substrates employing different buffer layer configurations.

AlGaN/GaN high electron mobility transistor (HEMT) structures are grown on 200-mm diameter Si(111) substrates by using three different buffer layer configurations: (a) Thick-GaN/3 × {AlxGa1-xN}/AlN, (b) Thin-GaN/3 × {AlxGa1-xN}/AlN, and (c) Thin-GaN/AlN, so as to have crack-free and low-bow (<50 µm) wafer. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, high resolution-cross section transmission electron microscopy, optical microscopy, atomic-force microscopy, cathodoluminescence, Raman spectroscopy, X-ray diffraction (ω/2θ scan and symmetric/asymmetric ω scan (rocking curve scan), reciprocal space mapping) and Hall effect measurements are employed to study the structural, optical, and electrical properties of these AlGaN/GaN HEMT structures. The effects of buffer layer stacks (i.e. thickness and content) on defectivity, stress, and two-dimensional electron gas (2DEG) mobility and 2DEG concentration are reported. It is shown that 2DEG characteristics are heavily affected by the employed buffer layers between AlGaN/GaN HEMT structures and Si(111) substrates. Particularly, we report that in-plane stress in the GaN layer affects the 2DEG mobility and 2DEG carrier concentration significantly. Buffer layer engineering is shown to be essential for achieving high 2DEG mobility (>1800 cm2/V∙s) and 2DEG carrier concentration (>1.0 × 1013 cm-2) on Si(111) substrates.