Biomedical subjects

T P Ng

Publications and source records attributed to T P Ng.

At least 19 recordsLinked to original sources

PubMed2003

Full weight bearing after non-cemented total hip replacement is compatible with satisfactory results.

Two matched groups of 29 patients underwent hydroxyapatite-coated non-cemented total hip replacement. One group was started on immediate protected-weight-bearing walking and the other group was started on immediate full-weight-bearing walking. They were followed up regularly for 2 years. They were assessed with Harris hip score clinically and Engh's criteria of osteo-integration radiographically. No difference was found between the two groups. All patients had excellent clinical outcome after hip replacement, and all femoral stems were stable radiographically. Patients can walk with full weight bearing safely immediate after hydroxyapatite-coated non-cemented total hip replacement.

Adult↗

PubMed2003

Trends and ethnic differences in hospital admissions and mortality for congestive heart failure in the elderly in Singapore, 1991 to 1998.

OBJECTIVES: To describe trends in hospital admissions and mortality from congestive heart failure in the elderly population aged 65 years and over in Singapore, 1991 to 1998. DESIGN: Analysis of trends and population subgroup differences in rates of hospital admission and mortality for a primary diagnosis of congestive heart failure, classified as ICD-9, codes 428, 402.0, 402.11, and 402.91. SETTING: The state of Singapore (multiethnic population of three million: Chinese 77%, Malay 14%, Indian 8%). RESULTS: Congestive heart failure accounted for 4.5% of all hospital admissions and 2.5% of overall mortality in this age group. Age adjusted hospital admission rates for congestive heart failure increased by 38% (from 85.4 per 10 000 in 1991 to 110.3 per 10 000 in 1998), while mortality decreased by 20% (from 7.3 per 10 000 in 1991 to 6.1 per 10 000 in 1998). The decline in mortality was greater in women than in men. There were no sex differences in the rates of hospital admission, but there were significant ethnic differences in admissions and mortality. Thus hospital admissions for congestive heart failure were about 35% higher in both Malays and Indians than in Chinese; and mortality was 3.5 times higher in Malays, but was about the same in Indians and Chinese. Over the period studied, mortality from congestive heart failure declined in both Chinese and Indians, but rose in Malays. The increases in hospital admissions were similar in both sexes and all ethnic groups. CONCLUSIONS: An increasing rate of hospital admission accompanied by declining mortality from congestive heart failure is occurring in elderly people in this Asian multiethnic population. However, there are pronounced ethnic differences, with both Malays and Indians showing higher hospital admission rates than Chinese, and Malays showing a rising mortality as opposed to the falling mortality in the other ethnic groups.

Aged↗

PubMed2003

Avoidable hospitalisation rates in Singapore, 1991-1998: assessing trends and inequities of quality in primary care.

STUDY OBJECTIVES: To assess avoidable hospitalisation as an indicator of quality of primary care by examining trends and gender and ethnic variations. DESIGN AND SETTING: Aggregated nationwide data in Singapore from 1991 to1998 were analysed for hospitalisations for chronic diseases that are avoidable by timely, appropriate, and effective primary care: asthma, congestive heart failure, chronic obstructive pulmonary disease, diabetes mellitus, and hypertension (avoidable hospitalisations). MAIN RESULTS: Of a total of 1 479 494 hospitalisations, 6.7% were for ambulatory care sensitive conditions (ACSC). The annual rate of avoidable hospitalisation was 29.4 per 10 000 population. Women had lower rates of avoidable hospitalisations than men (22.4 versus 29.5 per 10 000), as well as for total hospitalisations (496.2 versus 515.5 per 10 000). Adjusted for total hospitalisation, men were 1.3 times more likely than women to be hospitalised for ACSC. With similar adjustments for baseline utilisation, Indian and Malays had 1.7 and 1.8 times higher rates of avoidable hospitalisations than Chinese. Avoidable hospitalisation decline was -9.1% overall; greater in men (-11.8%) than in women (-5.3%); greater for Chinese (-15.8%), than Malays (-1.1%) and Indians (increase of +4.3%). CONCLUSION: Gender and ethnic differences and declining trends in avoidable hospitalisation demonstrated in this study suggest that avoidable hospitalisation rates are a sensitive indicator for assessing quality of primary ambulatory care.

Adolescent↗

PubMed2003

The shape and size of femoral components in revision total hip arthroplasty among Chinese patients.

OBJECTIVE: 39 sets of preoperative hip X-rays were studied to find out whether Chinese patients need revision femoral components with a different shape and size from western patients. METHODS: From July 1998 to June 2001, the pre-revision X-rays of 39 revision total hip replacements among 38 Chinese patients (21 men and 17 women) were studied. The component size that produced the best distal canal-filling in the anteroposterior X-ray was determined by using templates of 200-mm femoral components used commonly for Caucasian patients. RESULTS: The diameter of the component needed was 13.5 mm or less in 54% of cases, compared with only 17% for Caucasian patients as reported in the literature (p<0.01). When lateral templates of the corresponding size were put over the lateral X-rays, the anterior cortex of the 200-mm straight stem was shown to have thinned by 2.0 mm or more in 36% of hips; for 200-mm bowed stem, there was thinning of the anterior cortex by 2.0 mm or more in only 5% of hips (p<0.01). CONCLUSION: Chinese patients are likely to need smaller femoral components than Caucasian patients, and may benefit from bowed-stem components in femoral revision.

Adult↗

PubMed2002

Rhinitis: do diagnostic criteria affect the prevalence and treatment?

BACKGROUND: Rhinitis is one of the world's most common health problems. Diagnostic criteria used in community surveys may affect reported prevalence and treatment. METHODS: A proportionately stratified random sample study was performed to investigate the prevalence, comorbidities and management of community-based patients with rhinitis in the tropical urban city of Singapore. RESULTS: The prevalence of at least one, two, three, or four nasal symptoms on most days during the past year in our study population was 25.5%, 13.1%, 6.5%, and 3.0%, respectively. Based on the definition of 'rhinitis' by the International Consensus Report (ICR), the prevalence was 13.1% in Singapore. There was significantly higher prevalence of self-reported allergy, asthma, and common cold/influenza-like illness among the rhinitis group. In the 53% of rhinitis subjects seeking for medical help, 71% visited a primary care physician and 20% an otolaryngologist. Treatments as reported by patients were decongestants (topical or oral) 27%, antibiotics 12%, antihistamines 6%, nasal steroids 3%, surgery 2%, traditional methods 28%, and 22% did not know what medication they had. Subjects considered the effectiveness of treatment unsatisfactory because the majority of them had only partial or no relief with any treatment. CONCLUSIONS: The standardization of the definition of rhinitis in epidemiological studies is of crucial importance, especially when comparing the prevalence between studies. Appropriate patient education by physicians with a good understanding of the nature of rhinitis and the available treatment options (e.g. evidenced-based efficacy, safety, and a good cost-benefit ratio) will maximize patient compliance and treatment outcomes.

Adolescent↗

PubMed2002

Review article: knee flexion after total knee arthroplasty.

Many factors affect or predict the flexion range achieved after total knee arthroplasty. While the knees that have good preoperative flexion have better final flexion, knees with good preoperative flexion do lose some flexion whereas those with poor preoperative flexion can gain flexion. Although studies of different prosthetic designs have produced conflicting results, recent studies appear to favour posterior cruciate ligament (PCL)--substituting over PCL-retaining prostheses. Several factors related to surgical techniques have been found to be important. These include the tightness of the retained posterior cruciate ligament, the elevation of the joint line, increased patellar thickness, and a trapezoidal flexion gap. Vigorous rehabilitation after surgery appears useful, while continuous passive motion has not been found to be effective. Obesity and previous surgery are poor prognostic factors; certain cultural factors, such as the Japanese style of sitting, offer 'unintentional' passive flexion and result in patients with better range. If the flexion after surgery is unsatisfactory, manipulation under anaesthesia within 3 months of the total knee arthroplasty can be beneficial.

Arthroplasty, Replacement, Knee↗

PubMed2002

Influenza in Singapore: assessing the burden of illness in the community.

INTRODUCTION: Influenza infection has significant morbidity and mortality. The social and economic costs from work absence in the working population and from hospitalisations in the elderly are considerable. Meta-analyses of cohort and randomised controlled studies indicate that influenza vaccination is effective in preventing respiratory illness, hospitalization, pneumonia and death in 50% to 68% of cases. In Singapore, data on the disease burden from influenza are sparse and no official recommendation on influenza vaccination exists. METHOD: We estimated the disease burden of influenza-like illness (ILI), influenza infection in the general adult population, and hospitalisations and deaths from pneumonia and influenza, from routine official and published sources, and hoc community sample surveys, national virological surveillance, hospitalization and mortality data. RESULTS: In a resident population of 3 million people, there were 4.2 million cases of ILI in a typical non-epidemic year, 3.5 million visits to the doctor and 2.1 million days of work absence due to ILI. Data from the National Influenza Surveillance Programme indicated that about 15% of patients with ILI were positive for influenza isolates. We therefore estimated 630,000 cases of influenza virus infection cases a year, giving rise to 520,000 sick visits and 315,000 days of sick absence from work. About 4200 elderly (65+) persons were hospitalised for pneumonia and influenza, resulting in about 1450 deaths every year. The literature suggests a vaccine efficacy of about 50% of preventing influenza and its complications, including hospitalizations and deaths. This indicates that at least 315,000 cases of influenza virus infection, 258,000 sick visits, and 157,000 lost days from work in the whole population, and 2100 hospitalisations and 600 deaths from pneumonia in the elderly are potentially preventable by vaccination each year. CONCLUSION: Influenza poses a considerable burden of illness in the community and the potential benefits from influenza vaccination are substantial.

Adult↗

PubMed2001

The performance of three vacuum-mixing cement guns--a comparison of the fatigue properties of simplex P cement.

We tested three commercially available cement-mixing systems (Howmedica, Summit and Stryker). After mixing the cement was allowed to cure in metal moulds under standard conditions. Sixty-nine cement blocks were produced. The fatigue behavior of the blocks was tested until failure. A wide scattering of results was observed in all the three systems. Uneven mixing of the polymer and monomer was observed in the Howmedica system. A significantly stronger cement (P=0.018) was produced with the Stryker system.

Bone Cements↗

PubMed2001

Charnley total hip arthroplasty in Chinese patients less than 40 years old.

Forty-seven total hip arthroplasties were reviewed in 33 Chinese patients who were <40 years old at the time of operation. The preoperative diagnosis was avascular necrosis in 40% of the hips. A Charnley prosthesis was inserted using early cementing techniques in every hip. The average follow-up was 14.9 years (range, 6.9-21.1 years). The mean preoperative Harris hip score was 43.8 (range, 26-74), and the mean score at latest follow-up was 87.7 (range, 74-99) for the surviving hips. Thirty hips (63%) were revised, and 1 hip was removed because of late deep infection. The main cause of failure was aseptic loosening of the acetabular component. Using revision and radiologic loosening as endpoints, the cumulative survival rate for the acetabular component was 86.3% at 10 years and 27.0% at 15 years. The survival of the femoral components was 81.3% at 15 years. Patients with avascular necrosis had a higher failure rate than patients with other diagnoses (P =.001). An area of cement mantle that was <2 mm thick affected adversely the survival rate of the acetabular components (P =.04).

Adolescent↗

PubMed2001

Unusual complication associated with femoral intramedullary alignment guide in total knee arthroplasty.

The few reported complications related to the use of a femoral intramedullary alignment guide in total knee arthroplasty include increase in perioperative bleeding and fat embolism. We report 3 patients suffering from an unusual complication, concerning trapping of the tibial locking pin inside the intramedullary canal of the femur secondary to the use of an intramedullary alignment guide. Methods of retrieving the locking pin from the medullary canal are discussed.

Aged↗

PubMed2001

Cementless total hip arthroplasty in young Chinese patients: a comparison of 2 different prostheses.

Sixty-one primary cementless total hip arthroplasties were performed in 45 Chinese patients <40 years old. There were 27 Anatomic Medullary Locking (AML, Depuy, Warsaw, IN) prostheses and 34 Porous Coated Anatomic (PCA, Howmedica, Rutherford, NJ) prostheses. The average follow-up was 7.6 years (range, 3-11 years). Ten hips (16%) were reoperated; the reason was polyethylene wear with or without osteolysis in 7 hips. Osteolytic lesion was present in 34 hips (56%). The cumulative successful rate at 10 years was 67% using reoperation for any reason as the endpoint. The cumulative successful rate was 98%, however, if revision for aseptic loosening was used as the endpoint. The 2 prostheses did not show significant differences in most parameters except that the PCA hips had significantly more acetabular loosening (P =.02) and periprosthetic osteolysis (P =.01).

Adult↗

PubMed2001

Temporal trends and ethnic variations in amenable mortality in Singapore 1965-1994: the impact of health care in transition.

BACKGROUND: Amenable mortality is used to assess the effects of health care services on gains in mortality outcomes. Possibly differing patterns of trends in amenable mortality may be expected in economically less developed countries, which have undergone rapid epidemiological transition and recent reforms in health care systems, but such studies are scarce. This study was set up to examine the trends in amenable mortality in Singapore from 1965 to 1994; to estimate the relative impact of medical care and primary preventive policy measures in terms of gains in mortality outcomes; to examine ethnic differences in amenable mortality among Chinese, Malays and Indians. METHODS: Age-standardized mortality rates were calculated for 16 amenable causes of death in Singapore for six 5-year periods (1965-1969,..., 1990-1994), and for each of the three main ethnic groups for three periods (1989-1991, 1992-1994, 1995- 1997). Amenable mortality rates were divided into those which can be reduced by timely therapeutic care for 'treatable' conditions (e.g. asthma and appendicitis), or by primary preventive measures for 'preventable' conditions (e.g. lung cancer and motor vehicle injury). RESULTS: Amenable mortality was higher in males (age-standardized rate 109.7 per 100 000 population) than in females (age-standardized rate 60.7 per 100 000 population). Amenable mortality declined by 1.77% a year in males and 1.72% a year in females. By comparison, the average yearly decline in non-amenable mortality was 0.91% in males and 1.17% in females. The decline in amenable mortality was largely due to 'treatable' causes rather than a decline in mortality due to 'preventable' causes of death. Amenable mortality was lowest for Chinese and highest for Malays. Over the recent 9-year period from 1989 to 1997, amenable mortality declined more in Chinese than in Malays and Indians. However, Indian females showed by far the sharpest decline, whereas Indian males, by contrast, showed an increase in amenable mortality, due to both treatable and preventable causes. CONCLUSIONS: In line with findings from European countries, amenable mortality in Singapore declined more than non-amenable mortality. There were more significant gains in mortality outcomes from medical care interventions than from primary preventive policy measures. Gender and ethnic differences in amenable mortality were also observed, highlighting issues of socioeconomic equities to be addressed in the financing and delivery of health care.

Adolescent↗

PubMed2001

Radiological progression and its predictive risk factors in silicosis.

OBJECTIVES: To investigate the risk factors predicting radiological progression in silicosis in a prospective cohort study of patients with silicosis who were previously exposed to silica from granite dust. METHODS: From among a total of 260 patients with silicosis contracted from granite work, 141 with available serial chest x ray films of acceptable quality taken over a period of 2 to 17 (mean 7.5) years, were selected for study. Ninety four (66.7%) had ended exposure 5 or more years previously (mean 10.1 years, maximum 28 years). Radiological progression was assessed by paired comparison of the initial and most recent radiographs, with two or more steps of increase in profusion of small opacities according to the 12 point scale of the International Labour Organisation (ILO) classification of radiographs of pneumoconiosis, taken from the majority reading by a panel of three independent readers. RESULTS: Overall, 37% of patients with silicosis had radiological evidence of progression. From the initial radiographs, 24 (31.6%) of those with radiological profusion category 1, 15 (37.5%) of those with radiological profusion category 2, and 13 (52%) of those with complicated silicosis (including all seven with category 3 profusion of small opacities) showed radiological progression. As expected, progression was more likely to be found after longer periods of follow up (the interval between the two chest x ray films) with a 20% increased odds of progression for every additional year of follow up. After adjustment for varying intervals of follow up, the probability of radiological progression was found to be significant if large opacities were present in the initial chest x ray film. Progression was also less likely to be found among those who had ended exposure to silica longer ago, although the result was of borderline significance (p=0.07). Tuberculosis was also associated with increased likelihood of progression (borderline significance). CONCLUSIONS: There is a high probability of radiological progression in silicosis after high levels of exposure to granite dust among workers who were followed up for up to 17 years. A significant risk factor is the extent of radiological opacities in the initial chest x ray film. The probability of progression is also likely to be reduced with longer periods after the end of exposure.

Adolescent↗

PubMed2001

Nitrogen dioxide exposure from domestic gas cooking and airway response in asthmatic women.

BACKGROUND: Previous studies have not found a consistent association between exposure to domestic cooking using gas appliances and exacerbation of asthma. We investigated the immediate airflow response to acute exposure from single episodes of gas cooking, and peak airflow variability from continued exposure to repeated episodes of gas cooking in a group of non-smoking asthmatic women. METHODS: Sixteen adult non-smoking women with mild to severe persistent asthma were studied. The acute short term level of nitrogen dioxide (NO2) during gas cooking episodes and the mean exposure to NO2 from repeated gas cooking episodes were measured over a 2 week period, as well as proxy measures of frequency of cooking on each day and the length of time spent cooking each day. Their asthma status was monitored using peak expiratory flow rates (PEFR) before and after cooking, 2 week self-recorded serial readings of PEFR, respiratory symptom severity score, and use of rescue bronchodilators for acute asthma attacks. RESULTS: Cooking was significantly associated with an immediate mean fall in PEFR of 3.4% (p=0.015, paired t test). The acute short term NO2 level during cooking was significantly correlated with the fall in PEFR (r=-0.579; p=0.019). The frequency of cooking over a 2 week period was positively correlated with the mean exposure to NO2 (r=0.529; p=0.042). Continued exposure to NO2 over a 2 week period was associated significantly with increased frequency of rescue bronchodilator usage for asthma attacks (r=0.597; p=0.031). However, it was negatively associated with PEFR variability (r=-0.512; p=0.051) and respiratory symptom severity score (r= -0.567; p=0.043), probably due to the masking effects of bronchodilator treatment. CONCLUSIONS: Acute short term exposure to NO2 from single episodes of gas cooking is associated with immediate airflow limitation. Continued exposure from repeated episodes of gas cooking in asthmatic women is associated with greater use of rescue bronchodilators.

Adult↗

PubMed2001

Bilateral total knee arthroplasty: One mobile-bearing and one fixed-bearing.

We compared the early results of mobile-bearing knee prosthesis with fixed-bearing knee prosthesis in 16 patients who had one-stage, sequential, bilateral replacements. In each patient, a Low Contact Stress (LCS, Depuy) rotating-platform prosthesis was inserted in one side, and an Anatomic Modular Knee (AMK, Depuy) posterior-stabilised prosthesis was inserted in the other side. The same surgical routines were adopted for both sides in each patient. There were significant improvements in the Knee Society knee score and functional score, as well as the Oxford Knee score after both mobile-bearing and fixed-bearing knee replacements (p<0.001). However, we could not find any significant difference between the clinical results of the two prostheses. The authors early experience with the mobile-bearing total knee prosthesis was as favourable as the medium-term experience of the fixed-bearing total knee prosthesis in this prospective, match-pair study.

Journal Article↗

PubMed2001

Variations in ocular biometry in an adult Chinese population in Singapore: the Tanjong Pagar Survey.

PURPOSE: To describe the variation in ocular biometry in adult Chinese individuals in Singapore. METHODS: This study was a population-based, cross-sectional survey of adult Chinese persons aged 40 to 81 years residing in Tanjong Pagar district, Singapore. Axial ocular dimensions, including axial length (AL), anterior chamber depth (ACD), lens thickness (LT), and vitreous chamber depth (VCD) were measured using an A-scan ultrasound device. Corneal curvature (CC) and noncycloplegic refraction were measured with an autorefractor, with refraction further refined subjectively. Lens nuclear opacity (NO) was graded clinically using the modified Lens Opacity Classification System III (LOCS III) score. RESULTS: A total of 1717 subjects were eligible for the survey, of whom 1232 (71.8%) participated. Biometric and refraction data were available for 1004 (58.5%) phakic subjects. The AL, ACD, LT, VCD, CC, and LOCS III scores were 23.23 +/- 1.17 mm, 2.90 +/- 0.44 mm, 4.75 +/- 0.47 mm, 15.58 +/- 1.11 mm, 7.65 +/- 0.27 mm, and 3.2 +/- 0.9 (mean +/- SD), respectively. On average, people aged 40 to 49 years, when compared with those 70 to 81 years, had longer ALs (mean difference, +0.58 mm), deeper ACDs (+0.52 mm), longer VCDs (+0.72 mm), but thinner lenses (-0.70 mm) and less severe NO (-1.7 LOCS III score). CCs did not vary significantly with age. After controlling for age, women had shorter ALs and VCDs, shallower ACDs, but thicker lenses and steeper CCs than men. The variation in noncycloplegic refraction with age was nonlinear. Among people aged 40 to 59 years, a higher prevalence of hyperopia was seen in older compared with younger persons (on average, a difference of +1.3 D for every 10-year difference in age, P: < 0.001), explained principally by shorter AL (and VCD) in older persons. Among those 60 to 81 years, this pattern was not obvious (a difference of -0.03 D for every 10-year difference in age, P: = 0.12), as NO became an additional determinant of refraction, with greater degrees of NO in older person's driving refraction in the "minus" direction. CONCLUSIONS: Ocular dimensions vary with age and gender in adult Chinese persons in Singapore. The variation in noncycloplegic refraction in people 40 years and older may be explained by differences in axial lengths (principally vitreous chamber depths) between older and younger persons and, from 60 years onwards, differences in lens nuclear opacification as well.

Adult↗

PubMed2001

The design and assessment of questionnaires in clinical research.

Questionnaires are one of the most commonly used tools for data collection in clinical research. Despite its simplicity and convenience of use, the design of questionnaire instruments that accurately measure health status and their determinants is nevertheless a difficult and challenging task.We review the two most important issues which are reliability and validity. Reliability can be defined as the degree to which a measure gives 'consistent' or 'reproducible' values when applied in different situations. Validity refers to the extent in which the true value of a variable is correctly measured by the instrument. For different types of questionnaire measurement instruments, specific issues of content, construct and criterion validity should be appropriately addressed. Accuracy in questionnaire-based measurement in clinical studies is achieved by paying attention to the relevant specific issues of reliability and validity during development and testing of such questionnaires.

Reproducibility of Results↗

PubMed2000

Cloning and characterization of two hydrophobin genes differentially expressed during fruit body development in Lentinula edodes.

Hydrophobins play important roles in morphogenesis and pathogenesis in fungi and fruit development in mushrooms. Two genes encoding hydrophobins (Le.hyd1 and Le.hyd2) were isolated during sequencing of random clones from a primordial cDNA library of Lentinula edodes. The nucleotide sequences of these two genes were determined. These two genes are 760 and 738 bp in length and the deduced amino acid sequences are homologous to various fungal hydrophobins with characteristic cysteine spacing. These hydrophobin genes are Class I hydrophobins judging by their conserved domains and hydropathy patterns. The transcript level of Le.hyd1 is high in primordium and that of Le.hyd2 is high in dikaryotic mycelial tissues. Poor expression of these two genes in monokaryotic parents indicates that these two genes are under mating-type regulation. We thus suggest that differential expression of these two L. edodes hydrophobins during fruit development may contribute to their distinct roles in fruiting of this mushroom.

Amino Acid Sequence↗