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S C Li

Publications and source records attributed to S C Li.

At least 19 recordsLinked to original sources
PubMed2006

Suspended aggregates as an immobilization mode for high-density perfusion culture of HEK 293 cells in a stirred tank bioreactor.

Cells of the human embryonic kidney cell line (HEK 293) grown in repeated suspension and perfusion systems were characterized and described. Cell aggregates that formed immediately after the HEK 293 cells were inoculated in stirred vessels in serum-containing Dulbecco's modified Eagle's medium (D-MEM)/F-12 medium. The mean diameter of the cell aggregates reflecting the aggregate size increased with culture time, shifting from 63 to 239 mum after 1 and 8 days of culture in spinner flasks, respectively. No significant differences in cell performance were observed between HEK 293 cell populations grown as suspended aggregates and those grown as anchored monolayers. Replacing the D-MEM/F-12 with CD 293 medium caused the compact spherical cell aggregates to dissociate into single cells and small irregular aggregates without any apparent effect on cell performance. Moreover, the spherical cell aggregates could reform from individual cells and small aggregates when exposed to the serum-containing D-MEM/F-12 dominant medium. Perfusion culture of HEK 293 cells grown as suspended aggregates in a 7.5-l stirred tank bioreactor for 17 days resulted in a maximum viable cell density of 1.2 x 10(7) cells ml(-1). These results demonstrate the feasibility and proof-of-concept for using aggregates as an immobilization system in large-scale stirred bioreactors because a small-scale culture can be used as easily as the inoculum for larger bioreactors.

Bioreactors↗
PubMed2006

Meaning of health-related quality of life among children and adolescents in an Asian country: a focus group approach.

AIMS: We aimed to evaluate the extent to which HRQoL instruments developed based on the Western notion of health is applicable to Asian children and adolescents by assessing their conceptualization of QoL. A secondary objective is to evaluate the necessity of developing age- or gender-specific HRQoL instruments. METHODS: We explored the meaning of general and health-related QoL through focus group discussions in Singapore, a multi-ethnic Asian society. Two investigators independently analysed the data. They extracted major and sub-themes related to both general and health-related QoL. The agreement between the analyses was compared and disagreement was resolved through discussion. RESULTS: Thirty-two subjects (children: 50.0%, female: 50.0%) participated. There were few disagreements. Meanings of general and health-related QoL could be grouped under three broad themes: (1) physical, (2) psychological and (3) social health, consistent with the current definition of HRQoL. We found that Singaporean and Western children/adolescents share a remarkably similar notion of general and health-related QoL. Compared to adolescents, children were more likely to report positive emotions, be less mindful of others' opinions and had less varied social activities. CONCLUSION: The results suggest that currently available instruments are potentially useful for Singaporean children/adolescents. We also found that age-specific HRQoL instruments are necessary.

Adolescent↗
PubMed2005

Are they being used safely? A retrospective cross-sectional tertiary health care survey of selective serotonin reuptake inhibitors prescribing practice in Singapore.

OBJECTIVES: To determine the prescribing pattern of the SSRIs and to evaluate the safety of current utilization of SSRIs associated with concomitant psychotropic medications in Singapore. METHODS: The average prescribed daily dose (PDD) for each SSRI was calculated and compared with the defined daily dose (DDD). Pearson's chi2 test, one-way analysis of covariance (ANCOVA) and multinomial logistic regression were performed to examine the impacts of variables such as age, gender, patient type and concomitant psychotropic medications on the utilization of SSRIs. Safety issues were discussed by examining the potential metabolic drug interactions between the SSRIs and concomitant psychotropic medications. RESULTS: The most frequently prescribed SSRI was fluoxetine and the PDDs were slightly more than the DDDs for all these SSRIs except fluvoxamine. The SSRIs were mainly prescribed to the patients who were younger, female and outpatients. Psychotropics were more likely concomitantly used with fluvoxamine, sertraline and paroxetine, relative to fluoxetine. CONCLUSION: The prescribing pattern of SSRIs in a tertiary health center in Singapore is generally consistent with the accepted practices, although some safety concerns in terms of metabolic drug interactions were raised. This study provides useful baseline information for further in-depth studies for SSRIs usage both locally and for international comparison.

Adolescent↗
PubMed2005

Validity and reliability of the Chinese (Singapore) version of the Parkinson's Disease Questionnaire (PDQ-39).

OBJECTIVE: The purpose of the study was to validate the Chinese (Singapore) version of the Parkinson's Disease Questionnaire (PDQ-39CSV) and its briefer version (PDQ-8CSV). METHODS: A convenience sample of Chinese-speaking Singaporeans with Parkinson's disease (PD) (n = 63) completed a questionnaire containing the PDQ-39CSV and the Chinese (Singapore) EQ-5D. A subgroup also participated in a retest and/or a focus group discussion. A priori hypotheses were tested by examining correlations between PDQ-39CSV, PDQ-8CSV and EQ-5D scores and using principal component factor analysis. Reliability was assessed using Cronbach's alpha and intra-class correlation coefficients (ICC). RESULTS: Thirty-two PDQ-39CSV items correlated satisfactorily with their hypothesized dimensions (Spearman's p > or = 0.4). Factor analysis yielded a component on which all 8 PDQ-39CSV dimensions were substantially loaded (loading range: 0.53-0.89). As hypothesized, the PDQ-39CSV and PDQ-8CSV summary indices were highly correlated (Pearson's r:0.95, ICC:0.94); correlations between related PDQ and EQ-5D scores were generally strong (Spearman's p: 0.38-0.76, p < 0.001 for all). Cronbach's alpha values ranged from 0.64 to 0.90 and ICC values from 0.66 to 0.86. CONCLUSION: This study provides preliminary evidence supporting validity and reliability of both the PDQ-39CSV and its briefer version.

Adult↗
PubMed2005

Validation of the English version of the KINDL generic children's health-related quality of life instrument for an Asian population--results from a pilot test.

OBJECTIVES: To evaluate the psychometric properties of the KINDL questionnaire in an Asian population. METHODS: Consecutive patients with diabetes mellitus (DM) and healthy subjects were recruited to complete the English KINDL questionnaire. The inclusion criteria for patients were age 8-16 years, English-speaking, diagnosed with DM and absence of co-morbid conditions. RESULTS: Thirty children with DM (mean age: 10.7 +/- 1.35 years; 11 M) and 39 healthy subjects (mean age: 10.6 +/- 1.23 years, 17M) completed the child version whereas 31 adolescents with DM (mean age: 14.5 +/- 1.48 years; 15M) and 32 healthy subjects (mean age: 14.3 +/- 0.87 years, 16M) completed the adolescent version. Overall, children with DM reported better HRQoL than healthy children. Although this appeared counter-intuitive, several explanations are possible: (1) the development of resilience to the disease over time, (2) our subjects are well-managed, (3) response shift, (4) the provision of high quality medical care, (5) compared to normal children, diabetic subjects and their family pay greater attention to health issues. The reliability coefficients were (overall, scales): KINDL-Kid DM (0.79, 0.44-0.65), KINDL-Kid Healthy (0.71,0.60-0.80), KINDL-Kiddo DM (0.77, 0.37-0.74) and KINDL-Kiddo Healthy (0.84, 0.21-0.79). CONCLUSIONS: The KINDL questionnaire appeared promising for use in Asian children. However, further validation in a sample more representative of the general population is required.

Adolescent↗
PubMed2005

The European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-c30): validation of English version in Singapore.

OBJECTIVE: This study aimed to validate the European Organization for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC QLQ-C30, English version 3.0) in Singaporean cancer patients. METHODS: In a cross-sectional study, a heterogeneous sample of cancer patients (n = 57) self-administered a questionnaire containing the QLQ-C30, the Short Form 36 Health Survey (SF-36) and assessing health and sociodemographic status. Construct validity was assessed by testing a priori hypotheses that QLQ-C30 scales would be moderately or strongly correlated with SF-36 scales measuring similar dimensions of health-related quality of life (HRQoL) and that subjects reporting mild symptoms would have better HRQoL scores than those reporting severe symptoms. Internal consistency reliability was assessed using Cronbach's alpha. RESULTS: Strength of Spearman's correlations between the QLQ-C30 and SF-36 scales assessing similar dimensions of HRQoL ranged from 0.35 to 0.67. Subjects with mild symptoms had better scores than those with severe symptoms for all six QLQ-C30 HRQoL scales (p < 0.05 for five scales, Mann-Whitney U tests). Cronbach's alpha ranged from 0.19 for the cognitive functioning scale to 0.91 for the global QoL scale. CONCLUSION: This study provides preliminary evidence for the validity and reliability of the EORTC QLQ-C30 in English-speaking Singaporean cancer patients.

Adolescent↗
PubMed2005

Advice-giving on self-medication: perspectives of community pharmacists and consumers in Singapore.

BACKGROUND: In Singapore, community pharmacists provide an advice-giving service to consumers who seek self-medication for minor ailments management. This service has not been studied formally from the perspectives of pharmacists and consumers. OBJECTIVES: The study aimed to identify (i) the approach taken by pharmacists in providing advice for self-medication and (ii) consumers' behaviour in self-treatment and their perception of the advice-giving role of the community pharmacist. METHOD: The pharmacists and consumers were surveyed independently using two structured questionnaires. RESULTS AND DISCUSSION: All community pharmacists who participated in the survey were confident in providing advice on self-medication. However, none of them recorded the consultations and only 17.5% of them had documented their general physician referrals. Most consumers (66.3%) would self-medicate and only consult a professional when the desired outcome was not achieved. Less than 10% of consumers would approach the pharmacists as the first option for advice. More than half of the pharmacists felt that the advice they rendered deserved a fee whereas only 28.4% of the consumers were willing to pay. Both parties thought the fee should not be more than S5 dollars (US3 dollars). CONCLUSION: Generally, there is congruence in the perspectives on self-medication between the advice-giving pharmacist and the consumer. The consumers still lack awareness that pharmacists can help them to self-medicate more safely and effectively. Therefore, more effort in public education is warranted. The current state of poor documentation of the advisory function of community pharmacists should be improved.

Adult↗
PubMed2005

An evaluation of antimicrobial prophylaxis in paediatric surgery and its financial implication.

OBJECTIVE: To assess the appropriateness of use of antimicrobial prophylaxis in paediatric surgery in Singapore. METHODS: A prospective evaluation of the use of antimicrobial prophylaxis in paediatric patients undergoing surgery in KK Hospital, Singapore was carried out from September and December 2001. Process measures for the study included adherence to local or international guidelines, choice and dose of antimicrobial agent and timing and duration of prophylaxis. Outcome measures included surgical site and other related infections. A cost analysis was also performed to look at the extra expenditure due to any excessive use of antimicrobials. RESULTS: A total of 171 patients with a mean age of 5.7 years (SD=4.5) were included in the study. Among the 117 (68.4%) elective and 54 (31.6%) emergency procedures, 22 cases (12.8%) were fully compliant with the guidelines. The most frequently encountered non-compliance types were unnecessary prolongation of prophylaxis (54.4%), inappropriate choice of antibiotics (42.7%) and overdose of antibiotics (26.3%). The estimated extra cost to patients for the study period was Sing$13,879.41 (US 8164.36). CONCLUSION: The results showed a significantly high level of inappropriate use of antimicrobial prophylaxis in paediatric surgery in Singapore. However, when the individual factors such as appropriate choice of antibiotics, appropriate timing and duration were considered, the situation was very similar to the results obtained from overseas studies.

Antibiotic Prophylaxis↗
PubMed2005

Amylopectinosis disease isolated to the heart with normal glycogen branching enzyme activity and gene sequence.

We report a 17-month-old female patient with a rare cause of cardiomyopathy secondary to accumulation of amylopectin-like material (fibrillar glycogen) isolated to the heart. Evidence of amylopectinosis isolated to cardiac myocytes in this patient was demonstrated by histology and electron microscopy. Glycogen content, glycogen branching enzyme (GBE) activity, as well as phosphofructokinase enzyme activities measured in liver, skeletal muscle, fibroblasts and ex-transplanted heart tissue were all in the normal to lower normal ranges. Normal skeletal muscle and liver tissue histology and GBE activity, normal GBE activity in skin fibroblasts, plus normal GBE gene sequence in this patient exclude the classical branching enzyme deficiency (type IV GSD). We believe that this is an as yet uncharacterized and novel phenotype of GSD associated with cardiomyopathy, in which there is an imbalance in the regulation of glycogen metabolism limited to the heart.

1,4-alpha-Glucan Branching Enzyme↗
PubMed2004

Imaging cells and tissues with refractive index radiology.

Can individual cells, including live cells, be imaged using hard x rays? Common wisdom until now required sophisticated staining techniques for this task. We show instead that individual cells and cell details can be detected in culture solution and tissues with no staining and no other contrast-enhancing preparation. The sample examined can be much thicker than for many other microscopy techniques without sacrificing the capability to resolve cells. The key factor in our approach is the use of a coherent synchrotron source and of contrast mechanisms based on the refractive index. The first successful tests were conducted on a variety of cell systems including skin and internal leaf cells, mouse neurons, rabbit fibroblast cells, and human tumor cells.

Animals↗
PubMed2004

A retrospective drug utilization evaluation of vancomycin usage in paediatric patients.

OBJECTIVE: To evaluate the appropriateness of use of vancomycin in paediatric patients at KK Women's and Children's Hospital, the major paediatric hospital in Singapore to identify potential problems in prescribing practices that may necessitate intervention to optimize vancomycin usage. METHODS: A retrospective drug utilization evaluation was performed for paediatric patients who received intravenous vancomycin from 1 June 1998 to 31 June 1999. The outcome measures were consistency of vancomycin indication with recommended guidelines, dosing regimens, microbiological data, monitoring of serum drug levels, renal function, clinical outcomes and adverse drug reactions (ADRs). RESULTS: A total of 96 cases was available for evaluation. Sixty-two (64.6%) courses of vancomycin were consistent with guidelines for indication of therapy. Eighty-six (89.6%) of the dosing regimen were consistent. All infusion times that were recorded (56.3%) were consistent with criteria. Of the patients treated with vancomycin for more than 1 day, peak and/or trough serum vancomycin levels were ordered for 70 cases. Of the 56 cases with paired levels ordered, 46 cases had at least one level that fell outside the therapeutic range. Nineteen (19.8%) cases of ADRs were documented. Fifty-eight (60.4%) cases received concurrent nephrotoxic drugs. However, a substantial portion of vancomycin courses were apparently not prescribed for appropriate indications, and there was poor recording of vancomycin administration information and sampling time. CONCLUSION: The majority of dosing regimens of vancomycin was consistent with guideline criteria. The most evident problem was the sub-optimal use of the monitoring of vancomycin serum levels. The information derived from this study may be used as a for further study and for the development of strategies for optimize vancomycin usage.

Adolescent↗
PubMed2003

Validity and reliability of the EQ-5D self-report questionnaire in English-speaking Asian patients with rheumatic diseases in Singapore.

Validity and reliability of a Singaporean English EQ-5D self-report questionnaire (EQ-5D) were evaluated among consecutive outpatients with rheumatic diseases attending a tertiary referral hospital in Singapore (a multi-ethnic, urban Asian country). Subjects were interviewed twice within a 2-week period using a standardized questionnaire containing the EQ-5D, Short Form 36 Health Survey (SF-36) and assessing demographic and psychosocial characteristics. To assess validity of the EQ-5D, 13 hypotheses relating responses to EQ-5D dimension/Visual Analogue Scale (EQ-VAS) to SF-36 scores or other variables were examined using the Mann-Whitney test, Kruskal-Wallis test, or Spearman's correlation coefficient. Test-retest reliability was assessed using Cohen's kappa. Sixty-six subjects were studied (osteoarthritis: 9, rheumatoid arthritis: 26, systemic lupus erythematosus: 23, spondyloarthropathy: 8; female: 72.7%; mean age: 44.3 years). Ten of 13 a-priori hypotheses relating EQ-5D responses to external variables were fulfilled, supporting the validity of the EQ-SD. Cohen's kappa for test-retest reliability (n = 52) ranged from 0.29 to 0.61. The Singaporean English EQ-5D appears to be valid in measuring quality of life in Singaporeans with rheumatic diseases; however, its reliability requires further investigation. These data provide a basis for further studies assessing the validity of the EQ-5D in Singapore.

Adolescent↗
PubMed2003

Validity and reliability of the EQ-5D self-report questionnaire in Chinese-speaking patients with rheumatic diseases in Singapore.

OBJECTIVE: We assessed the psychometric properties of a Singaporean Chinese version of the EQ-5D, a health-related quality of life (HRQoL) instrument. MATERIALS AND METHODS: Consecutive outpatients with rheumatic diseases seen for routine follow-up consultations at the National University Hospital, Singapore were interviewed twice within 2 weeks using a standardised questionnaire containing the EQ-5D, the Short-Form 36 Health Survey (SF-36), the Learned Helplessness Subscale, a pain Visual Analogue Scale (VAS) and assessing demographic and psychosocial characteristics. To assess the validity of the EQ-5D, 13 hypotheses relating the EQ-5D self-classifier (5 dimensions) or visual analogue scale (EQ-VAS) to SF-36 scores or other variables were examined using the Mann-Whitney U test, Kruskal-Wallis or Spearman's correlation coefficient. Test-retest reliability was assessed using Cohen's kappa. RESULTS: Forty-eight subjects were studied (osteoarthritis: 16; rheumatoid arthritis: 22; systemic lupus erythematosus: 8; spondyloarthropathy: 2; female: 93.8%; mean age: 56.4 years). Seven of 13 a-priori hypotheses relating EQ-5D to external variables were fulfilled, supporting the validity of the EQ-5D. For example, subjects reporting moderate or extreme problems for EQ-5D dimensions generally had lower median SF-36 scores than those without such problems. Cohen's kappa for test-retest reliability of the self-classifier ranged from 0.41 to 1.00 (n = 42; median interval: 7 days, interquartile range: 7 to 11 days). CONCLUSIONS: The Singaporean Chinese EQ-5D self-classifier appears to be a valid measure of HRQoL in Singaporeans with rheumatic diseases; however, the reliability of the EQ-VAS requires further investigation. These data provide a basis for further studies of the Singaporean Chinese EQ-5D.

Activities of Daily Living↗
PubMed2002

Public awareness of diabetes mellitus in Singapore.

INTRODUCTION: Much effort has been devoted to educating the public about diabetes. However, the impact of such efforts has yet to be formally evaluated. OBJECTIVES: To identify areas of knowledge that might require additional educational efforts. METHODOLOGY: A cross-sectional survey was conducted to evaluate the general public's knowledge of diabetes. The respondents were required to answer 45 questions from a pre-tested questionnaire divided into five main sections, namely, general knowledge, risk factors, symptoms and complications, treatment and management, monitoring and other miscellaneous questions. A point was awarded for each correct response and zero for wrong or unsure responses. The maximum total score was 41. The miscellaneous questions were not scored. RESULTS: A total of 1337 subjects were interviewed. The mean score obtained by the respondents was 66.1% of the maximum possible total score (i.e. 27.1 points out of 41). The "correct answer" percentages for the individual questions from each section ranges from 22 to 83% (General knowledge), 31 to 91% (Risk factors), 48 to 81% (Symptoms and complications), 35 to 87% (Treatment and management), and 58 to 93% (Monitoring of condition).With respect to the source of medical information, health care professionals did not feature prominently (20.7%). CONCLUSION: The public as represented by the samples in this survey is generally well informed about diabetes except for a few areas. Analysis of these areas would have a significant implication for future public education programme. Health care professionals should be more proactive in disseminating health information about diabetes to the public.

Adolescent↗
PubMed2002

A study of the effectiveness of AIDS health education interventions among the adolescent population of Singapore.

AIM OF STUDY: This study aims to evaluate the effectiveness of existing AIDS health education interventions in Singapore amongst the adolescent population of Singapore. By identifying specific target groups that lack knowledge and information regarding HIV, it is hoped that suggestions may be provided towards increasing the effectiveness of these interventions. METHOD: A cross-sectional survey using a self-administered questionnaire of randomly selected adolescents between the ages of 13 and 19 years was performed to assess their knowledge of HIV and their opinions and awareness of HIV education in Singapore. RESULTS: A total of 400 adolescents of various backgrounds were surveyed. In general, the subjects surveyed possessed reasonably good knowledge about HIV/AIDS, with an average score of 77.4% (SD = 15.8%). However, the results also showed areas of knowledge deficiency and misconception prevalent among those surveyed. Subgroup analysis showed that adolescents from low-income families, relatively less academically successful schools and those of younger ages knew significantly less than other adolescents. In terms of the awareness of HIV/AIDS education and information, the percentage of the subjects who could recognise any of the three commonly issued pamphlets or poster or who knew of any telephone numbers to call to receive information on HIV and AIDS was low. Less than 40% of those surveyed felt that enough awareness was being created within the public regarding AIDS. CONCLUSION: It can be concluded that most adolescents surveyed felt that they are inadequately educated regarding HIV andAIDS. The results would certain target groups using the appropriate media in future educational intervention.

Adolescent↗
PubMed2001

Degradation of G(M1) and G(M2) by mammalian sialidases.

In mammalian tissues, the pathway known for the catabolism of G(M1) [Galbeta3GalNAcbeta4(Neu5Acalpha3)Galbeta4GlcCer; where Cer is ceramide] is the conversion of this ganglioside into G(M2) [GalNAcbeta4(Neu5Acalpha3)Galbeta4GlcbetaCer] by beta-galactosidase followed by the conversion of G(M2) into G(M3) (Neu5Acalpha3Galbeta4GlcbetaCer) by beta-N-acetylhexosaminidase A (Hex A). However, the question of whether or not G(M1) and G(M2) can also be respectively converted into asialo-G(M1) (Galbeta3GalNAcbeta4Galbeta4GlcCer; G(A1)) and asialo-G(M2) (GalNAcbeta4Galbeta4GlcbetaCer, G(A2)) by mammalian sialidases has not been resolved. This is due to the fact that sialidases purified from mammalian tissues always contained detergents that interfered with the in vitro hydrolysis of G(M1) and G(M2) in the presence of an activator protein. The mouse model of human type B Tay-Sachs disease created by the disruption of the Hexa gene showed no neurological abnormalities, with milder clinical symptoms than the human counterpart, and the accumulation of G(M2) in the brains of affected mice was only limited to certain regions [Sango, Yamanaka, Hoffmann, Okuda, Grinberg, Westphal, McDonald, Crawley, Sandhoff, Suzuki and Proia (1995) Nat. Genet. 11, 170-176]. These results suggest the possible presence of an alternative catabolic pathway (the G(A2) pathway) in mouse to convert G(M2) into G(A2) by sialidase. To show the existence of this pathway, we have used recombinant mammalian cytosolic sialidase and membrane-associated sialidase to study the desialylation of G(M1) and G(M2). We found that the mouse membrane-bound sialidase was able to convert G(M1) and G(M2) into their respective asialo-derivatives in the presence of human or mouse G(M2) activator protein. The cytosolic sialidase did not exhibit this activity. Our results suggest that, in vivo, the stable NeuAc of G(M1) and G(M2) may be removed by the mammalian membrane-associated sialidase in the presence of G(M2) activator protein. They also support the presence of the G(A2) pathway for the catabolism of G(M2) in mouse.

Animals↗
PubMed2001

Order parameter of MgB(2): a fully gapped superconductor.

We have measured the low-temperature specific heat C(T) for polycrystalline MgB(2) prepared by high pressure synthesis. C(T) below 10 K vanishes exponentially, which unambiguously indicates a fully opened superconducting energy gap. However, this gap is found to be too small to account for T(c) of MgB(2). Together with the small specific heat jump Delta C/gamma(n)T(c) = 1.09, scenarios such as anisotropic s-wave or multicomponent order parameter are called for. The magnetic field dependence of gamma(H) is neither linear for a fully gapped s-wave superconductor nor H(1/2) for nodal order parameter. It seems that this intriguing behavior of gamma(H) is associated with the intrinsic electronic properties other than flux pinning.

Journal Article↗