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Biomedical subjects

T L Tan

Publications and source records attributed to T L Tan.

At least 19 recordsLinked to original sources
PubMed2004

Impact of a pharmacist consult clinic on a hospital-based geriatric outpatient clinic in Singapore.

INTRODUCTION: We study the impact of a pharmacist consult clinic on the care of elderly outpatients based on the Health Belief Model that the perceived benefits (improvement in medication knowledge, clinical status and perception) and attached barriers (cost and number of medication and adverse drug reactions) can influence health behaviour (medication compliance). MATERIALS AND METHODS: A randomised controlled study of 136 eligible patients with risk factors for non-compliance, using Zelen's design, was conducted in a hospital-based geriatric outpatient clinic from November 2001 to June 2002. All patients were assessed for outcome variables at baseline and 2 months later. RESULTS: One hundred and twenty-six patients were included in the intention-to-treat analysis. There were 104 pharmacist interventions with a physician acceptance rate of 76%. There was a significant improvement in medication knowledge with regards to indication (P = 0.03) and the composite dose, frequency and indication score (P = 0.06), as well as a decrease in residual adverse drug reactions that persisted at month 2 and cost avoidance of dollars 387.28 over 2 months. There was no significant difference in perception, clinical status or decrease in number of medications. The intervention group showed an improvement in adjusted compliance (odds ration [OR] = 2.52; 90% confidence interval [CI], 1.09 to 5.83) based on the ordered logistic regression model. Perception of severity of illness at baseline (OR = 1.30; 90% CI, 1.04 to 1.62), number of medication remembering methods (OR = 1.87; 90% CI, 1.08 to 3.25) and the use of routine habits (OR = 4.48; 90% CI, 1.51 to 13.28) and medication aids (OR = 3.68; 90% CI, 1.04 to 13.06) significantly affected compliance. CONCLUSION: The addition of a pharmacist consult clinic to the management of selected geriatric outpatients can improve compliance, with the attendant benefits of improving medication knowledge, cost avoidance and reducing residual adverse drug reactions.

Aged↗
PubMed2003

FT-IR study of a chemically amplified resist for X-ray lithography.

Microelectronic devices for future applications demand lithographic performance that falls within the 0.10 microm region and below. Chemically amplified resists (CARs), such as the positive tone commercial UVIII resist, offer a substantial gain in sensitivity, resolution, and process efficiency in deep ultraviolet, e-beam, and X-ray lithographies. In this work, the UVIII resist is characterized for X-ray lithographic applications by studying the "deprotection" or acid generation-diffusion process of the resist under different conditions of post-exposure bake (PEB) temperature and time, and of X-ray exposure dose. The X-ray irradiation from a copper anode at a wavelength of 1.33 nm was at an intensity of 30 microW/cm2 on the resist surface. The deprotection process of the resist during PEB was accurately monitored by using Fourier transform infrared (FT-IR) spectroscopy. The infrared absorption peaks at 1151, 1369, and 2977 cm(-1) in the spectrum of the UVIII resist were found to be useful indicators for the completion of deprotection. Results of the experiments showed that the performance of UVIII could be optimized at the PEB temperature of 140 degrees C, a time of 2 min, and X-ray exposure dose of 12 mJ/cm2. The change in resist thickness after PEB was also measured. The results were confirmed by scanning electron microscopy (SEM) in which a test structure as small as 0.12 microm was obtained in a 1-microm-thick UVIII resist layer.

Acrylates↗
PubMed2003

Urinary incontinence in older persons: a simple approach to a complex problem.

Urinary incontinence is a major geriatric syndrome with significant morbidity and even mortality. However, it is under-recognised and inadequately managed despite its impact and cost. Continence in the older person is maintained by the fine balance between the integrity of the lower urinary tract, the cognitive ability and motivation to keep dry, and adequate mobility and dexterity to void; impairment of any of the three can result in incontinence. The management of older persons with urinary incontinence involves, i) identifying and reversing transient incontinence, ii) excluding urinary retention, iii) deciding on the need of special tests (imaging, screening for malignancy, magnetic resonance imaging [MRI] for spinal cord, urodynamic assessment) to exclude sinister causes, and iv) deciding on the need to refer the specialist. With careful evaluation, continence in the older persons can be restored in most cases.

Aged↗
PubMed2001

Characterization of facultative oligotrophic bacteria from polar seas by analysis of their fatty acids and 16S rDNA sequences.

One hundred and seventy three bacterial strains, isolated previously after enrichment under oligotrophic, psychrophylic conditions from Arctic (98 strains) and Antarctic seawater (75 strains), were characterized by gas-liquid chromatographic analysis of their fatty acid compositions. By numerical analysis, 8 clusters, containing 2 to 59 strains, could be delineated, and 8 strains formed separate branches. Five clusters contained strains from both poles, two minor clusters were confined to Arctic isolates, and one cluster consisted of Antarctic isolates only. The 16S rRNA genes from 23 strains, representing the different fatty acid profile clusters and including the unclustered strains, were sequenced. The sequences grouped with the alpha and gamma Proteobacteria, the high percent G+C gram positives, and the Cytophaga-Flavobacterium-Bacteroides branch. The sequences of strains from 4 clusters and of 7 unclustered strains were closely related (sequence similarities above 97%) to reference sequences of Sulfitobacter mediterraneus, Halomonas variabilis, Alteromonas macleodii, Pseudoalteromonas species, Shewanella frigidimarina, and Rhodococcus fascians. Strains from the other four clusters and an unclustered strain showed sequence similarities below 97% with nearest named neighbours, including Rhizobium, Glaciecola, Pseudomonas, Alteromonas macleodii and Cytophaga marinoflava, indicating that the clusters which they represent form as yet unnamed taxa.

Alphaproteobacteria↗
PubMed2001

Impaired mobility in older persons attending a geriatric assessment clinic: causes and management.

OBJECTIVES: To study the profile of older persons with impaired mobility. METHODS: A retrospective observational study that reviewed the case records of patients with impaired mobility at a geriatric assessment clinic. Data on mobility status, duration of decline in mobility, functional status, causes, intervention and short-term outcome (up to 16 weeks) were extracted and analysed. RESULTS: The study included 78 patients (42 males) with the median age of 78 years (61 to 96). About 80% had independent premorbid mobility. At presentation, this declined to 45%. Delayed consultations (more than 2 years) were found in 17% of patients. One third had associated decline in transfer, dressing, toileting or bathing, while 19% also had decline in feeding. In each patient, cause(s), many which were potentially reversible, were identified to have contributed to the immobility. More than one cause was identified in half of the patients. Interventions were prescribed in 88% of these patients. Short-term follow-up (median 7 weeks) showed that 21 had an improvement, 35 had the same and 8 had decline in mobility. There was a significant trend towards better outcome when patient presented early during their course of decline in mobility (p=0.005, linear by linear association = 0.013). CONCLUSION: Impaired mobility is a common pathway for many diseases, and is associated with significant functional decline. With proper evaluation, the offending causes can be identified. Early consultation is important for the application of appropriate intervention and can result in better outcome.

Activities of Daily Living↗
PubMed2001

Urinary retention in hospitalised older women.

INTRODUCTION: Information about urinary retention in women is scarce. We conducted a case-control study to identify the symptoms and risk factors associated with urinary retention in hospitalised older women. MATERIALS AND METHODS: Targeted history (especially lower urinary tract symptoms) and physical examination of 60 women (65 years or older) who had post-void residual urine volume (PRUV) (determined using a portable ultrasound Bladder Scan BVI-2500) of more than 100 mL were studied and compared with 60 controls. RESULTS: Symptoms of voiding difficulties had low positive predictive value (PPV) and negative predictive value (NPV), except for poor stream, which has a PPV of 100%. Only one-third of the patients with high PRUV had a palpable bladder. Associated with high PRUV were: 1) constipation [odds ratio (OR), 4.12; 95% confidence interval (CI), 1.90-8.91; P = 0.0004]; 2) urinary tract infection (UTI) (OR, 3.36; 95% CI, 1.58-7.12; P = 0.002); 3) impaired mobility (OR, 2.37; 95% CI, 1.12-4.97; P = 0.02); 4) past history of UTI (OR, 3.5; 95% CI, 1.34-9.14; P = 0.014); 5) past history of urinary retention (OR, 6.33; 95% CI, 1.72-23.33; P = 0.004); 6) stroke (OR, 2.5; 95% CI, 1.24-5.41; P = 0.017); 7) diabetes mellitus with microvascular complications (OR, 2.76; 95% CI, 1.08-7.04; P = 0.042). Applying logistic regression analysis, the three best predictive variables for high PRUV were constipation, UTI and past history of urinary retention. CONCLUSION: Symptoms (except for positive history of poor stream) and signs were unreliable in diagnosing urinary retention in hospitalised older women. Patients with the above risk factors should have their PRUV ascertained, which can be done reliably non-invasively. Early detection with appropriate intervention can potentially prevent the morbidity and mortality associated with urinary retention.

Aged↗
PubMed2000

High resolution FTIR spectrum of the nu1 band of DCOOD.

Accurate spectral information on formic acid has wide application to radioastronomy since it was the first organic acid found in interstellar space. In this work, the infrared absorption spectrum of the nu1 band of deuterated formic acid (DCOOD) has been measured on a Bomem DA3.002 Fourier transform spectrometer in the wavenumber region 2560-2690 cm(-1) with a resolution of 0.004 cm(-1). A total of 292 infrared transitions have been assigned in this hybrid type A and B band centred at 2631.8736 +/- 0.0004 cm(-1). The assigned transitions have been fitted to give a set of eight rovibrational constants for the nu1 = 1 state with a standard deviation of 0.00078 cm(-1).

Formates↗
PubMed2000

Disruption of mouse SNM1 causes increased sensitivity to the DNA interstrand cross-linking agent mitomycin C.

DNA interstrand cross-links (ICLs) represent lethal DNA damage, because they block transcription, replication, and segregation of DNA. Because of their genotoxicity, agents inducing ICLs are often used in antitumor therapy. The repair of ICLs is complex and involves proteins belonging to nucleotide excision, recombination, and translesion DNA repair pathways in Escherichia coli, Saccharomyces cerevisiae, and mammals. We cloned and analyzed mammalian homologs of the S. cerevisiae gene SNM1 (PSO2), which is specifically involved in ICL repair. Human Snm1, a nuclear protein, was ubiquitously expressed at a very low level. We generated mouse SNM1(-/-) embryonic stem cells and showed that these cells were sensitive to mitomycin C. In contrast to S. cerevisiae snm1 mutants, they were not significantly sensitive to other ICL agents, probably due to redundancy in mammalian ICL repair and the existence of other SNM1 homologs. The sensitivity to mitomycin C was complemented by transfection of the human SNM1 cDNA and by targeting of a genomic cDNA-murine SNM1 fusion construct to the disrupted locus. We also generated mice deficient for murine SNM1. They were viable and fertile and showed no major abnormalities. However, they were sensitive to mitomycin C. The ICL sensitivity of the mammalian SNM1 mutant suggests that SNM1 function and, by implication, ICL repair are at least partially conserved between S. cerevisiae and mammals.

Amino Acid Sequence↗
PubMed1999

Mouse Rad54 affects DNA conformation and DNA-damage-induced Rad51 foci formation.

Error-free repair by homologous recombination of DNA double-strand breaks induced by ionizing radiation (IR) requires the Rad52 group proteins, including Rad51 and Rad54, in the yeast Saccharomyces cerevisiae [1]. The formation of a 'joint' molecule between the damaged DNA and the homologous repair template is a key step in recombination mediated by Rad51 and stimulated by Rad54 [2] [3] [4] [5]. Mammalian homologs of Rad51 and Rad54 have been identified [2] [3] [6]. Here, we demonstrate that mouse Rad54 (mRad54) formed IR-induced nuclear foci that colocalized with mRad51. Interaction between mRad51 and mRad54 was induced by genotoxic stress, but only when lesions that required mRad54 for their repair were formed. Interestingly, mRad54 was essential for the formation of IR-induced mRad51 foci. Rad54 belongs to the SWI2/SNF2 protein family, members of which modulate protein-DNA interactions in an ATP-driven manner [7]. Results of a topological assay suggested that purified human Rad54 (hRad54) protein can unwind double-stranded (ds) DNA at the expense of ATP hydrolysis. Unwinding of the homologous repair template could promote the formation or stabilization of hRad51-mediated joint molecules. Rad54 appears to be required downstream of other Rad52 group proteins, such as Rad52 and the Rad55-Rad57 heterodimer, that assist Rad51 in interacting with the broken DNA [2] [3] [4].

Adenosine Triphosphate↗
PubMed1998

Obesity without sleep apnea is associated with daytime sleepiness.

BACKGROUND: Daytime sleepiness and fatigue is a frequent complaint of obese patients even among those who do not demonstrate sleep apnea. OBJECTIVE: To assess in the sleep laboratory whether obese patients without sleep apnea are sleepier during the day compared with healthy controls with normal weight. METHODS: Our sample consisted of 73 obese patients without sleep apnea, upper airway resistance syndrome, or hypoventilation syndrome who were consecutively referred for treatment of their obesity and 45 controls matched for age. All patients and healthy controls were monitored in the sleep laboratory for 8 hours at night and at 2 daytime naps, each for 1 hour the following day. RESULTS: Obese patients compared with controls were sleepier during the day and their nighttime sleep was disturbed. During both naps, sleep latency, wake time after onset of sleep, and total wake time were significantly lower, whereas the percentage of sleep time was significantly higher in obese patients compared with controls. In contrast, during the nighttime testing, obese patients compared with controls demonstrated significantly higher wake time after onset of sleep, total wake time, and lower percentage of sleep time. An analysis of the relation between nighttime and daytime sleep suggested that daytime sleepiness in obese patients is a result of a circadian abnormality rather than just being secondary to nighttime sleep disturbance. CONCLUSIONS: Daytime sleepiness is a morbid characteristic of obese patients with a potentially significant impact on their lives and public safety. Daytime sleepiness in individuals with obesity appears to be related to a metabolic and/or circadian abnormality of the disorder.

Adolescent↗
PubMed1997

A novel, highly efficient peptide-HLA class I binding assay using unfolded heavy chain molecules: identification of HIV-1 derived peptides that bind to HLA-A*0201 and HLA-A*0301.

A novel cell-free, highly automated peptide-HLA binding assay has been designed during which a mixture of unfolded recombinant HLA heavy chain molecules, beta 2-microglobulin and a fluorescent labeled standard peptide is allowed to form peptide-HLA complexes. The binding of a peptide of interest is monitored as the ability to inhibit the formation of fluorescent peptide-HLA complexes. The assay was validated using published, known HLA-A* 0201 and HLA-A* 0301 binding peptides. In addition a selected set of HIV-1LAI reverse transcriptase derived 10-mer peptides, that had been selected on the basis of HLA-A* 0201 or HLA-A* 0301 binding motifs, were tested for HLA-A* 0201/A* 0301 binding. In that set we identified 8 peptides which bound with high affinity to HLA-A* 0201 and 5 peptides which bound with high affinity to HLA-A* 0301. The major advantage of the use of denatured heavy chain is the improved economy and efficiency, as unfolded protein material is in principle easily accessible by recombinant technology.

HIV Reverse Transcriptase↗
PubMed1995

Can morbidly obese patients safely lose weight preoperatively?

BACKGROUND: Preoperative weight loss is often suggested as a means of reducing operative risk in obese patients requiring laparotomy but there are no large studies documenting that this is feasible or helpful. Although several commercial products are available that provide high levels of protein with low levels of carbohydrates in convenient liquid preparations, recommendations regarding the extent to which weight loss can be pursued preoperatively are not available. PURPOSE: To determine whether it is practical and safe to have obese patients lose weight preoperatively. PATIENTS AND METHODS: We asked 100 severely obese patients requesting gastric bypass surgery to diet before their operations. Seventy patients agreed to diet by consuming a 420 Kcal, 70 g protein liquid diet daily for at least 1 month. RESULTS: Forty-seven patients lost at least 7.5 kg (mean +/- SD 17.1 +/- 0.7). The patients who successfully lost weight preoperatively (dieters group) were significantly heavier than patients (nondieters group) who did not lose weight (251% +/- 45% of ideal body weight [IBW] versus 229% +/- 33% IBW, respectively; P < 0.01), had a significantly higher ratio of men to women, and had psychiatric evaluations and psychological test scores that suggested significantly more psychopathology. Other biosocial and medical characteristics were similar. Postoperatively, the dieters and nondieters had similar rates for morbidity. Dieters and nondieters had no differences in wound-healing complications, and subgroups who had collagen deposition measured experimentally had similar amounts of hydroxy-proline accumulation in their wounds. CONCLUSION: These results suggest that a preoperative diet program appeals more to certain subgroups of severely obese patients than to others. An aggressive preoperative weight loss program that encourages patients to lose an average of 17 kg is safe and can be accomplished practically using available commercial products.

Female↗
PubMed1995

Comparison of the costs associated with medical and surgical treatment of obesity.

BACKGROUND: We compared the long-term costs and outcomes of gastric bypass versus medical therapy (very low-calorie diet plus weekly behavioral modification) for obese patients. METHODS: A successful outcome was defined as the loss of at least one third of excess weight that was maintained for the duration of the study. A minimal cost was assigned: $3000 for medical and $24,000 for surgical treatment. A cost per pound of weight lost for all patients successfully monitored was calculated. The Federal Trade Commission recently asked all weight loss programs to report this cost for patients at least 2 years after therapy. RESULTS: A total of 201 patients entered surgical and 161 entered medical therapy. The surgical group was initially heavier (mean body mass index [kg/m2] +/- SE = 49.3 +/- 0.6 versus 41.2 +/- 0.7, p < 0.01), but each group's lowest mean body mass index was similar (31.8 versus 32.1, respectively). A significantly higher percentage of patients in the surgical versus the medical group were still successful at year 5: 89% versus 21%. The cost per pound lost for medical therapy exceeded the cost of surgical therapy in the sixth posttreatment year (both more than $250/pound). CONCLUSIONS: Surgical treatment appears to be more cost-effective at producing and maintaining weight loss. It is imperative that long-term follow-up studies be funded to definitely establish this finding.

Adolescent↗
PubMed1994

Sleep apnea and sleep disruption in obese patients.

OBJECTIVES: To describe the frequency and severity of sleep apnea in obese patients without a primary sleep complaint and to assess the sleep patterns of obese patients without apnea and compare them with the sleep patterns of nonobese controls. DESIGN AND SETTING: Prospective case series with historical controls in an obesity and sleep disorders clinic. SUBJECTS: Two hundred obese women and 50 obese men (mean body mass index, 45.3) consecutively referred for treatment of their obesity and 128 controls matched for age and sex. MAIN OUTCOME MEASURES: Eight-hour sleep laboratory recording, including electroencephalogram, electro-oculogram, electromyogram, and respirations. Subjectively reported sleep-related symptoms and signs were also recorded. RESULTS: Twenty men (40%) and six women (3%) demonstrated sleep apnea warranting therapeutic intervention. Another four men (8%) and 11 women (5.5%) showed sleep apneic activity that warranted recommendation for evaluation in the sleep laboratory. In contrast, none of the 128 controls demonstrated sleep apneic activity severe enough for therapeutic intervention. The best clinical predictors of sleep apnea in the obese population were severity of snoring, subjectively reported nocturnal breath cessation, and sleep attacks. Obese patients, both men and women, without any sleep-disordered breathing demonstrated a significant degree of sleep disturbance compared with nonobese controls. Wake time after sleep onset, number of awakenings, and percentage of stage 1 sleep were significantly higher in obese patients than in controls, while rapid eye movement sleep was significantly lower. CONCLUSION: Severely or morbidly obese men are at extremely high risk for sleep apnea and should be routinely evaluated in the sleep laboratory for this condition, while for severely or morbidly obese women the physician should include a thorough sleep history in the clinical assessment.

Adolescent↗
PubMed1991

Preoperative insurance status influences postoperative complication rates for gastric bypass.

One hundred morbidly obese patients who had gastric bypass surgery were studied to determine how various demographic and medical variables affected complication rates, weight loss, and reduction in comorbidities associated with obesity. During the follow-up period (range: 12 to 59 months), 42 patients developed at least 1 complication. Twenty-three patients developed postoperative medical complications, 9 developed psychiatric complications, and 24 developed complications related to food ingestion. No significant relationships were observed between outcome and age, sex, age of obesity onset, or associated medical disorders. Striking differences in outcome were noted, however, when patients were contrasted according to their preoperative insurance status. Patients dependent on medical assistance, social security disability, or workman's compensation (publicly funded group) (n = 40) developed significantly more medical and psychiatric complications than did those (n = 60) who had private medical insurance (p less than 0.02). Despite the higher complication rate, both groups had the same average weight loss (44.9 +/- 15.3 kg for the publicly funded group versus 43.1 +/- 12.9 kg for those with private insurance) and similar reductions in percent excess weight (66.0 +/- 18.4% versus 75.7 +/- 23.0%) during the first postoperative year. All patients also had similar reductions in medication requirements for hypertension, diabetes, and degenerative joint disease. Additionally, 45% of the publicly funded insurance group who either received public welfare (n = 26) or disability benefits (n = 14) preoperatively were able to attain either full-time or part-time employment postoperatively which allowed them to decrease their level of support (58% and 21%, respectively). Forty-six percent of women in the private insurance group who were not working outside the home also began part-time or full-time employment postoperatively. All patients who were working preoperatively continued to work. These data suggest that although the risks associated with gastric bypass surgery are greater in patients dependent on public funding, these patients benefit significantly from the surgery.

Adolescent↗
PubMed1990

No difference in expression of chromosomal fragile sites in patients with solid malignant tumours and normal controls.

The frequency and distribution of rare and common chromosomal fragile sites in metaphases derived from peripheral lymphocytes were compared in 26 patients with malignant solid tumours and 24 normal controls. In order to avoid bias in evaluation, the identity of each individual as patient or control was disclosed only after the study was completed. Rare heritable folic acid inducible fragile sites were found in five patients (2q13; 6p23; 8q22; 16p12) and two controls (8q22). Common fragile sites were present in 21 of 26 patients and in 19 of 24 controls. These differences are statistically not significant in the Fisher test. We conclude that the expression of fragile sites does not indicate a predisposition for solid tumours.

Chromosome Fragile Sites↗