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Biomedical subjects

T Tan

Publications and source records attributed to T Tan.

At least 55 records · Page 3Linked to original sources
PubMed1999

Classification and management of perforations complicating endoscopic sphincterotomy.

BACKGROUND: The management of perforations after endoscopic sphincterotomy (ES) is controversial. The purpose of this study was to analyze the treatments and outcome of patients with ES perforations. METHODS: Between January 1994 and July 1998, in a series of 6040 endoscopic retrograde cholangiopancreatographies, 2874 (48%) ESs were performed: 40 patients (0.6%) with perforation were identified and retrospectively reviewed. RESULTS: All patients (n = 14) with guidewire perforation (group I) were recognized early, managed medically, and discharged after a mean hospital stay of 3.5 days. Twenty of 22 patients with periampullary perforation (group II) were identified early; 18 patients (90%) had aggressive endoscopic drainage, and none required operation. Of the 2 patients identified late, 1 patient required operation and subsequently died. Mean hospital stay for this group was 8.5 days. Only 1 of 4 patients with duodenal perforations (group III) was identified early; all required operation; 1 patient died, and the mean hospital stay was 19.5 days. CONCLUSIONS: ES perforation has 3 distinct types: guidewire, periampullary, and duodenal. Guidewire perforations are recognized early and resolve with medical treatment. Periampullary perforations diagnosed early respond to aggressive endoscopic drainage and medical treatment. Postsphincterotomy perforations diagnosed late (particularly duodenal) require surgical drainage, which carries a high morbidity and mortality rate.

Abscess↗
PubMed1999

[Study on the radioligand binding assay of cholecystokinin receptor in rat cerebral cortex].

A radioligand binding assay system for determining the characterization of CCK receptor is presented. Using Bolton-Hunter reagent, we prepared a biologically active, specific 125I-BH-CCK8. The iodination mixture was then transferred to a column of Sephadex G-25 and examined by silica thin layer chromatography. Its specific activity and radiochemical purity were 3.4 TBq/mmol and 96% respectively. Binding of 125I-BH-CCK8 to the membrane of rat cerebral cortex was rapid, reversible, time-temperature dependent, saturable and specific. The labeled CCK was shown to have biological activity as measured by the CCK receptor radioassay. Under our laboratorial conditions, the CCK binding required an hour to reach equilibrium at 4 degrees C. We chose polyethylene glycol 6,000 and gamma-globulin protein for the separation of B and F. Scatchard plot of CCK binding was linear with a Kd value of 1.098 nmol/L and Bmax of 197.5 fmol/mg protein. The results of this study support the stand-point that CCK may function as a regulatory peptide in brain and hence may be of use for clarifying the CCK receptor's function in central nervous system.

Animals↗
PubMed1999

[Left ventricular function evaluation after mitral valve replacement with preservation the subvalvular apparatus].

The objective of this study was to evaluate the left ventricular function after mitral valve replacement (MVR) with preservation of all chordae. Fourteen patients with a diagnosis of mitral regurgitation were studied. These patients, 4 males and 10 females, age from 24 to 59 years, who underwent mitral valve replacement, in which all chordae tendineae were preserved. The mean follow-up interval was 6 months. Preoperation and postoperation multigated equilibrium radionuclide angiography was performed by Elscint Helix Apex SPECT. Each patient was injected with 740MBq 99mTc-HSA, rest ejection fraction (global EF) of LV (%), regional ejection fraction (EF) of LV (%), PER/S and PFR/S were measured. Regional EF was calculated by the method of dividing the left ventricle into five segments by radial axis. The results showed that the postoperative EF of the whole left ventricle of the chordae-preserved patients was significantly greater than their preoperative EF (40.0% +/- 17.8%, to 51.6% +/- 18.2%, P < 0.02), and also the regional EF at the lateral wall of the chordae-preserved MVR was significantly greater than the preoperative regional EF (an increase from 51.0% +/- 18.1% to 69.7% +/- 21.2%, P < 0.01). MVR with preservation of all chordae, the patient's left ventricular function remarkably improved.

Adult↗
PubMed1999

[Prospects for antisense techniques].

Antisense technique, developed on the principle of base complementation, is a method using short strand oligonucleotide fragments complementary to target DNAs or target RANs for inhibition of gene expression. As a theoretically perfect and specific method to block the expression of gene, it has been rapidly developed over the last twenty years. This review expatiates on its techniques, its problem and possible way of problem-solving, and its recent application in medicine. Also this review discusses the trends of its further development.

Animals↗
PubMed1998

A new allele of interferon-alpha17 gene encoding IFN-alpha17b is the major variant in human population.

Thirteen interferon (IFN)-alpha functional genes have been reported. Among these, a number of genes have allelic members (variants). In the case of IFN-alpha17, five variants, IFN-alpha17a, IFN-alpha17b, IFN-alpha17c, IFN-alpha17d, and IFN-alphaT, are known. The variants differ from each other by base changes in the coding region, leading to differences in amino acid sequences. We have developed oligonucleotide primers for amplification of IFN-alpha17 gene(s) using polymerase chain reaction (PCR). Genomic DNA, obtained from over 28,000 normal healthy individuals and from four cell lines, were used as templates in PCR to amplify the IFN-alpha17 gene sequences. The resulting PCR products were analyzed by restriction endonuclease digestion and DNA sequencing to identify the presence of variant sequences. The results show that a new variant of IFN-alpha17 is abundantly present (approximately 70%) along with another variant, possibly IFN-alpha17c (approximately 30%), in the genomic DNA of the population examined. This new variant, the protein product of which is identical to IFN-alpha17b, differs from the gene for IFN-alpha17b by a point mutation. We have named it IFN-alpha17b', which is the only variant found in U-937, KG-1, and EB-3 cell lines. Namalwa cells have IFN-alpha17b' and, possibly, IFN-alpha17c in equal proportions.

Alleles↗
PubMed1998

[A pharmacokinetic study of 125I-VIP in rat].

To investigate the pharmacokinetics of 125I-VIP in normal rats, a single dose of 125I-VIP was given intravenoualy to rats and from 0.5 to 240 min after the administration, serial blood samples were taken and measuredp by gamma scintillation counter and finally expressed as mu Ci/ml blood. The data were analyzed by computer for the estimation of pharmacokinetic parameters and the judgment of compartment model with a program of 3P87. The results demonstrated that the pharmacokinetics of 125I-VIP in rat fitted with the three-compartment model(Wi = 1) based on either the comparison of the calculated theoretic value with measured concentration, the values of AIC and r2 or F test for the model judgment, and that the average distributive half-life of 125I-VIPk in blood was 1.36 min, the elimination half-life(T1/2 beta was 67.3 min, the K12(3.589 min-1) was markedly higher than that of K12(0.045 min-1), and the K21:K12(0.0127) was obviously lower than that of K31:K13(0.215). The present study indicates that 125I-VIP has a rapid uptake and slow elimination in the tissues with high density and affinity VIP receptors (the second compartment).

Animals↗
PubMed1998

[Rapid microdose 14C-urea breath test for detection of Helicobacter pylori infection].

The purpose of this study was to develop and evaluate a rapid microdose 14C-urea breath test (14C-UBT) with a simplified protocol for detecting the infection of hilicobacter pylori (HP). 157 fasting patients who underwent endoscopy with histological examination and rapid urease test (RUT) were given a drink of 37 kBq of 14C-urea. Samples of breath carbon dioxide (1 mmol) were collected at baseline and 10, 20 and 30 min after administration by trapping in hyamine solution. 14C activity was measured by liquid scintillation counting. Results were expressed as cpm. Histolal examination and RUT were used as gold standard for the detection of HP infection. The cutoff value was selected as 200 cpm at 10 min. The results showed that the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 94.79%, 90.16%, 93.81%, 91.60% and 92.99% respectively. In this study, a 10 min, single sample, 37 kBq 14C-urea breath test for detection HP was developed. The test has good diagnostic accuracy with minimal radiation exposure and low cost. Thus, the authors considered the test to be reliable, safe, convenient and cost-effective to clinical use.

Adolescent↗
PubMed1998

Study on kinetics of ergosterol fermentation.

The kinetic relationships among the consumption of sucrose, production of ergosterol, formation of ethanol, and growth of yeast cells were studied. A two-stage kinetic model was established. The relative deviations between experimental data and simulated results were no more than 20%.

Ergosterol↗
PubMed1998

A survey of patients' knowledge of anaesthesia and perioperative care.

AIM: The present study was undertaken to assess patients' knowledge of anaesthesia and perioperative care as well as their perception of anaesthetics and their role. METHODOLOGY: A questionnaire survey of 23 items was developed and completed pre-operatively by 132 patients. Included in this study were 45 men and 87 women; 80% with at least secondary education with a mean age of 39.9 and 35.6 years, respectively. RESULTS: Results indicated that only 56.8% of patients understood that anaesthetists are doctors. There were significant misconceptions though in general, knowledge was good. Although all patients realised the importance of fasting, however only 74.2% of patients realised it meant limitation of both solids and liquids from a specified time. Pain was the major concern among the patients surveyed (39.4%), followed by fear of not waking up after surgery (18.9%). Twenty-one per cent of patients believed that postoperative pain was a necessary part of the healing process and 28% thought that pain was something that they had to put up with in the postoperative period. Only 23.5% correctly identified the anaesthetist as being responsible for analgesia in the recovery period. A majority (75.8%) wished to have more information about anaesthesia. CONCLUSION: When forthcoming surgery and anaesthesia are discussed, it is important that patients realise that they are being cared for by anaesthetists who are doctors and efforts must be taken to educate the profession and public on the anaesthetists' role in perioperative care. This should enhance the professional image of anaesthesia and more importantly, improve patient confidence and quality of care.

Adult↗
PubMed1997

Cognitive testing of elderly Chinese people in Singapore: influence of education and age on normative scores.

AIM: to establish age- and education-adjusted mean psychometric test scores of cognitively normal elderly Chinese people in Singapore. METHOD: 155 community-living, cognitively intact elderly Chinese subjects, stratified according to age and education, were selected from the membership lists of senior citizens' clubs and were administered a neuropsychological assessment battery. The mean test scores were then analysed for correlations with demographic characteristics. RESULTS: only education and age were independent variables; gender and language spoken were strongly correlated with education by the chi2 method (P < 10[-5]). Subsequent statistical analysis of education and age on the psychological test scores by the general linear model procedure enabled the formulation of a table of age- and education-adjusted normative cognitive scores. CONCLUSION: the derivation of age- and education-adjusted normative scores of a selected neuropsychological assessment battery on elderly Chinese people enables a more accurate diagnosis of dementia to be made and may facilitate better international comparisons of this condition. As our subjects are representative of many others from China, these results may serve not only as a local, but also as a regional, reference source.

Age Factors↗
PubMed1996

Producing positive, negative, and no cooperativity by mutations at a single residue located at the subunit interface in the aspartate receptor of Salmonella typhimurium.

Site-directed mutagenesis of the aspartate receptor of Salmonella typhimurium (Tars) at serine 68, a residue located within the aspartate binding pocket and at the subunit interface, identified this residue as an allosteric switch in this receptor. Substitutions at this position can affect both the type and degree of binding cooperativity observed. Negative cooperativity is observed in the wild-type receptor (nH = 0.7 +/- 0.1) and is maintained by the mutations S68C (nH = 0.8 +/- 0.02), S68V (nH = 0.9 +/- 0.05), and S68D (half-of-the-sites). Binding at only half of the sites was detectable in the S68D mutant, an extreme form of negative cooperativity. No cooperativity (nH = 1.0 +/- 0.03) was observed in the mutant S68A. Positive cooperativity was generated by the substitutions S68T (nH = 1.2 +/- 0.09), S68L (nH = 1.2 +/- 0.1), S68N (nH = 1.3 +/- 0.2), and S68I (nH = 1.4 +/- 0.2). Binding measurements indicated that the substitutions S68Q, S68E, and S68F decrease affinity of the first ligand binding 500-fold, 7000-fold, and 1600-fold, respectively.

Allosteric Regulation↗
PubMed1996

Purification of phosphoglycerate kinase and glyceraldehyde phosphate dehydrogenase by DEAE-sepharose fast flow chromatography.

The purification of phosphoglycerate kinase (PGK) and glyceraldehyde phosphate dehydrogenase (GAPDH) from soy bean was studied by a DEAE-sepharose fast flow chromatography. When scaling up, the diameters of columns increase but the heights of columns were maintained in the range of 10 to 20 cm to avoid the problem of the high pressure drop. The recovery of GAPDH and PGK was 57% and 41%, respectively. The purification factor of GPADH and PGK was 144 and 44, respectively. The economical evaluation indicated that the cost of the process was 2.09$/ku GAPDH, which has some commercial values.

Chromatography, Ion Exchange↗
PubMed1995

[Effect of 153Sm-EDTMP on hematopoiesis and vital organs of 93 patients with bone tumor].

In the present study data on blood cell count, serum biochemistry, electrolyte, enzyme and vital organs of 93 patients with bone tumor or metastasis were investigated before and after treatment with 153Sm-EDTMP. The results showed that, 7 days and 30 days after the administration of 153Sm-EDTMP (< 29.6 MBq) (0.8 mCi/kg), the levels of hemoglobin, WBC lymphocyte count, and the liver and kidney function of all patients were not significantly different from the baseline data before treatment (P > 0.05). Although at 7 days, there was a declination of the granulocyte count, it returned to normal at 30 days (P > 0.05). The platelet count was significantly decreased (0.05 > P > 0.01). at 30 days after the administration of 153Sm-EDTMP. Thirteen patients received 74-185 MBq (2-5mCi/kg) and their myelo biopsies at 3 and 18 months showed no sign of acute or chronic toxicosis.

Adult↗
PubMed1995

[Effect of Cladonia alpestris on Trichomonas vaginalis in vitro].

In this paper, an experimental research is reported on the effect of water extract of Cladonia alpestris and S-(-) usnic acid on Trichomonas vaginalis in vitro. The results showed that both the water extract of Cladonia alpestris and S-(-)usnic acid exhibited a strong effect against Trichomonas vaginalis in vitro. As the time of action of the agents was prolonged, the mortality of Trichomonas vaginalis increased. For S-(-) usnic acid, 0.4 mg/ml was the lowest effective concentration against Trichomonas vaginalis in vitro. No remarkable differences were found in the effect of the S-(-)usnic acid and metronidazole at concentrations of 0.4 mg/ml and 0.6 mg/ml.

Animals↗
PubMed1995

[153Sm-EDTMP for moderate and severe bone cancer pain].

One hundred and thirty-six patients with bone cancer pain were treated with 153Sm-EDTMP (ethylenediamine-tetramethylene phosphonic acid). Pain free was noted in 49 cases (36%, 49/136) and pain relief in 77 cases (56.6%, 77/136), the total relief rate being 92.6% (126/136). The data from 76 patients with moderate and severe pain showed there were no significant relationships between the patients' age, the dose of 153Sm-EDTMP and the analgesic effects (P > 0.05). The pain relief observed in the patients with chest pain (ribs metastases) was earlier than that in other groups (P < 0.05). We didn't find any clinical side-effects, so 153Sm-EDTMP is safe for use.

Adult↗
PubMed1995

Bullous systemic lupus erythematosus--a case report and review.

We report a case of a 20-year-old Chinese woman who presented with an 8-month history of a widespread pruritic blistering eruption. Histology, direct immunofluorescence and indirect immunofluorescence studies were consistent with bullous systemic lupus erythematosus (SLE). The lesions responded dramatically to dapsone 100 mg daily. Bullous SLE is a rare blistering condition with a distinctive combination of clinical, histologic and immunopathologic features that together constitute a unique bullous disease phenotype. The differential diagnoses and in particular the association between bullous SLE and epidermolysis bullosa acquisita are emphasized.

Adult↗