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Biomedical subjects

T Z Tan

Publications and source records attributed to T Z Tan.

14 recordsLinked to original sources

Review of patients with infective endocarditis of native valves over a five-year period.

The clinical characteristics, echocardiographic features, bacteriologic data, morbidity and mortality of patients who were admitted to our hospital with infective endocarditis of their native valves over a five-year period were reviewed. There were 32 patients with a mean age of 38.2 +/- 16.2 years (range: 17 to 71 years) in our study population; 24 patients had underlying valvular abnormalities, six patients had congenital heart disease and two patients had no structural cardiac abnormality. Echocardiography was performed for all patients. Vegetations were absent in three (9.4%) patients, single in 19 (59.4%) patients and multiple in ten (31.3%) patients. Of the 24 (75%) patients who had left-sided endocarditis, mitral valve disease was the commonest valvular abnormality (16 patients). Ventricular septal defect was the commonest underlying abnormality in patients with right-sided endocarditis. Blood cultures were positive in 26 (81.3%) patients; the commonest organism was streptococcal (16 or 50% patients). Complications were present in 13 (40.6%) patients, of which eight patients had evidence of embolism, four patients had cardiac failure and one patient had a paravalvular abscess. Four (12.5%) patients died, two as a result of refractory heart failure and two as a consequence of septic embolism. Advances in medicine have resulted in a better outcome for patients with infective endocarditis, however, it remains an important disease with significant morbidity and mortality.

Adolescent↗

Anticancer gelatin microspheres with multiple functions.

Biodegradable, hydrophilic gelatin microspheres (GM) with an average diameter of 70 microns were prepared by cross-linking gelatin with glutaraldehyde for hepatic intra-arterial infusion. An anticancer agent, mitomycin C (MMC), together with a radioisotope, 131I, were bound to the GM for chemotherapy and local internal radiotherapy. The 131I-labelled MMC-GM (131I-MMC-GM) could accumulate in the specific site and embolize the hepatic arteries after the hepatic intra-arterial infusion, while it caused various effects to the liver cells. The 131I-MMC-GM remained within the hepatic arteries for at least one month. In vitro release of drugs from the GM was also quantified using a dynamic dialysis method.

Animals↗

[Autoradiographic studies on the metabolism of gingival glycosaminoglycans in experimental periodontitis].

The purpose of this study was to investigate the changes in glycosaminoglycans (GAGs) of the gingiva during a period of experimental periodontitis induced by placing a silk ligature below the gingival margin of dog molars. Incorporation of 3H-glucosamine into the gingiva was determined autoradiographically. The gingiva was collected at 0, 7, 21, 60 and 90 days and cultured in vitro in the presence of 3H-glucosamine. The autoradiographs showed a predominantly epithelial location of the silver grains in all gingival epithelia. The location was intercellular in all epithelia. The results suggest greater 3H-glucosamine incorporation by the epithelium compared with the connective tissue and markedly more rapid metabolic turnover of epithelial GAGs.

Animals↗

[The pharmacokinetic study of 3H-alpha-2-butylhydroxybenzyl alcohol in rabbits].

A derivative of Gastrodigenin, alpha-2-butylhydroxybenzyl alcohol, has shown a high distribution in the mice brain and stronger pharmacologic effects than its parent compounds. With 3H-alpha-2-butylhydroxybenzyl alcohol as radioactive tracer, pharmacokinetic data were obtained after the intravenous administration of a single dose alpha-2-butylhydroxybenzyl alcohol to rabbits, according to a cross-over design. Then, serial plasma samples were taken from 1 min to 480 min and measured by liquid scintillation counter. The data were analyzed by IBMPC computer for the estimation of pharmacokinetic parameters and the judgement of compartment model with a program recently developed by ourselves. The results suggested that the pharmacokinetics of alpha-2-butylhydroxybenzyl alcohol accords with the two compartment open model based on either the comparison of the calculated theoretic value with measured concentration or F test for the model judgement, and that the process of distribution was quite rapid, and the elimination half-life (T1/2 beta) was 12 h, indicating a slow elimination process.

Animals↗

[The distribution of 3H-alpha-sec-butyl-p hydroxybenzyl alcohol in mice].

alpha-sec-butyl-p-hydroxybenzyl alcohol is a derivative of gastrodigenin. It dissolves in lipid and passes through the blood-brain barrier more easily than gastrodin does. The distribution experiment has demonstrated that 3H-alpha-sec-butyl-p-hydroxybenzyl alcohol in the brain of mice is higher than in other organs, such as the liver, kidney and intestines. Radioactivity of brain tissue rises to the highest peak in about 1/2-2 min after intravenous injection. Each gram of the brain tissue takes up 21.89% radioactivity of the total dose administered. The sedative effect of alpha-sec-butyl-p-hydroxybenzyl alcohol on the center is rapid and short. It has been proved by the reactions in mice, results indicated by the electrocorticogram obtained from the mice after giving alpha-sec-butyl-p-hydroxybenzyl alcohol, and the correspondence with the distribution of alpha-sec-butyl-p-hydroxybenzyl alcohol in the mouse brain.

Animals↗

Ovarian cancer diagnosis by hippocampus and neocortex-inspired learning memory structures.

Early detection and accurate staging of ovarian cancer are the keys to improving survival rate. However, at present there is no single diagnosis modality that is sufficiently sensitive. DNA microarray analysis is an emerging technique that has potential for ameliorating the hardship in early detection and staging of ovarian disease. However, microarray data is ultra-huge and difficult to analyze. Hence, computational intelligence methods are often utilized to assist in the diagnosis and analysis process. Fuzzy Neural Networks (FNN) are more suitable for this task as FNN provides not only the accuracy, but also the interpretability of its reasoning process. Hippocampus-inspired Complementary Learning FNN (CLFNN) is able to rapidly derive fuzzy sets and formulate fuzzy rules. CLFNN uses positive and negative learning, and hence it reduces the effect of the curse of dimensionality and is capable of modeling the dynamics of the problem space with relatively good classification performance. One of its successors, a hybrid of complementary hippocampal learning and associative neocortical learning called Pseudo Associative Complementary Learning (PACL), is a structure that seeks to functionally model the memory consolidation process. Both PACL and CLFNN have human-like reasoning that allows physicians to examine their computation using familiar terms. They can construct intuitive fuzzy rules autonomously to justify their reasoning, which is important to generate trust among the users. Hence, CLFNN and PACL are applied as a diagnostic decision support system in ovarian cancer diagnosis. The experimental results are encouraging.

Algorithms↗