Biomedical subjects

M C Liu

Publications and source records attributed to M C Liu.

228 records · Page 13Linked to original sources

PubMedDate not supplied

Study of the quantitative structure-mobility relationship of carboxylic acids in capillary electrophoresis based on support vector machines.

The support vector machines (SVM), as a novel type of learning machine, were used to develop a quantitative structure-mobility relationship (QSMR) model of 58 aliphatic and aromatic carboxylic acids based on molecular descriptors calculated from the structure alone. Multiple linear regression (MLR) and radial basis function neural networks (RBFNNs) were also utilized to construct the linear and the nonlinear model to compare with the results obtained by SVM. The root-mean-square errors in absolute mobility predictions for the whole data set given by MLR, RBFNNs, and SVM were 1.530, 1.373, and 0.888 mobility units (10(-5) cm(2) S(-1) V(-1)), respectively, which indicated that the prediction result agrees well with the experimental values of these compounds and also revealed the superiority of SVM over MLR and RBFNNs models for the prediction of the absolute mobility of carboxylic acids. Moreover, the models we proposed could also provide some insight into what structural features are related to the absolute mobility of aliphatic and aromatic carboxylic acids.

Journal Article↗

PubMedDate not supplied

QSAR models for the prediction of binding affinities to human serum albumin using the heuristic method and a support vector machine.

The binding affinities to human serum albumin for 94 diverse drugs and drug-like compounds were modeled with the descriptors calculated from the molecular structure alone using a quantitative structure-activity relationship (QSAR) technique. The heuristic method (HM) and support vector machine (SVM) were utilized to construct the linear and nonlinear prediction models, leading to a good correlation coefficient (R2) of 0.86 and 0.94 and root-mean-square errors (rms) of 0.212 and 0.134 albumin drug binding affinity units, respectively. Furthermore, the models were evaluated by a 10 compound external test set, yielding R2 of 0.71 and 0.89 and rms error of 0.430 and 0.222. The specific information described by the heuristic linear model could give some insights into the factors that are likely to govern the binding affinity of the compounds and be used as an aid to the drug design process; however, the prediction results of the nonlinear SVM model seem to be better than that of the HM.

Humans↗

PubMedDate not supplied

Diagnosing anorexia based on partial least squares, back propagation neural network, and support vector machines.

Support vector machine (SVM), as a novel type of learning machine, for the first time, was used to develop a predictive model for early diagnosis of anorexia. It was based on the concentration of six elements (Zn, Fe, Mg, Cu, Ca, and Mn) and the age extracted from 90 cases. Compared with the results obtained from two other classifiers, partial least squares (PLS) and back-propagation neural network (BPNN), the SVM method exhibited the best whole performance. The accuracies for the test set by PLS, BPNN, and SVM methods were 52%, 65%, and 87%, respectively. Moreover, the models we proposed could also provide some insight into what factors were related to anorexia.

Anorexia↗

PubMedDate not supplied

Quantitative prediction of logk of peptides in high-performance liquid chromatography based on molecular descriptors by using the heuristic method and support vector machine.

A new method support vector machine (SVM) and the heuristic method (HM) were used to develop the nonlinear and linear models between the capacity factor (logk) and seven molecular descriptors of 75 peptides for the first time. The molecular descriptors representing the structural features of the compounds only included the constitutional and topological descriptors, which can be obtained easily without optimizing the structure of the molecule. The seven molecular descriptors selected by the heuristic method in CODESSA were used as inputs for SVM. The results obtained by SVM were compared with those obtained by the heuristic method. The prediction result of the SVM model is better than that of heuristic method. For the test set, a predictive correlation coefficient R = 0.9801 and root-mean-square error of 0.1523 were obtained. The prediction results are in very good agreement with the experimental values. But the linear model of the heuristic method is easier to understand and ready to use for a chemist. This paper provided a new and effective method for predicting the chromatography retention of peptides and some insight into the structural features which are related to the capacity factor of peptides.

Artificial Intelligence↗

PubMedDate not supplied

Support vector machines-based quantitative structure-property relationship for the prediction of heat capacity.

The support vector machine (SVM), as a novel type of learning machine, for the first time, was used to develop a Quantitative Structure-Property Relationship (QSPR) model of the heat capacity of a diverse set of 182 compounds based on the molecular descriptors calculated from the structure alone. Multiple linear regression (MLR) and radial basis function networks (RBFNNs) were also utilized to construct quantitative linear and nonlinear models to compare with the results obtained by SVM. The root-mean-square (rms) errors in heat capacity predictions for the whole data set given by MLR, RBFNNs, and SVM were 4.648, 4.337, and 2.931 heat capacity units, respectively. The prediction results are in good agreement with the experimental value of heat capacity; also, the results reveal the superiority of the SVM over MLR and RBFNNs models.

Journal Article↗

PubMedDate not supplied

Comparative study of QSAR/QSPR correlations using support vector machines, radial basis function neural networks, and multiple linear regression.

Support vector machines (SVMs) were used to develop QSAR models that correlate molecular structures to their toxicity and bioactivities. The performance and predictive ability of SVM are investigated and compared with other methods such as multiple linear regression and radial basis function neural network methods. In the present study, two different data sets were evaluated. The first one involves an application of SVM to the development of a QSAR model for the prediction of toxicities of 153 phenols, and the second investigation deals with the QSAR model between the structures and the activities of a set of 85 cyclooxygenase 2 (COX-2) inhibitors. For each application, the molecular structures were described using either the physicochemical parameters or molecular descriptors. In both studied cases, the predictive ability of the SVM model is comparable or superior to those obtained by MLR and RBFNN. The results indicate that SVM can be used as an alternative powerful modeling tool for QSAR studies.

Animals↗

PubMedDate not supplied

Treatment of refractory or relapsed adult acute leukemia by using mitoxantrone-containing regimens.

Twenty-eight adult patients with primary refractory or relapsed acute leukemia were treated. The regimens consisted of mitoxantrone plus cytosine arabinoside for 17 patients with acute non-lymphocytic leukemia (ANLL) and mitoxantrone accompanied with vincristine and prednisolone for 11 patients with acute lymphoblastic leukemia (ALL). In primary refractory patients, 1 of the 4 (25%) ANLL and 1 of the 3 (33%) ALL attained complete remission (CR). Excluding 2 patients who underwent bone marrow transplantation, 8 of the 13 (62%) relapsed ANLL and 4 of the 8 (50%) relapsed ALL achieved CR with a median duration of remission of 6.2 months and 3.8 months, respectively. Myelosuppression occurred in all treatment courses and was associated with pyrexia due to infections in 84% of the cases. Nausea, vomiting and stomatitis were mild. Abnormal liver function tests were observed in 8 (28%) patients. One patient, pretreated with 550 mg/m2 of doxorubicin, developed congestive heart failure. The results suggest that mitoxantrone is of value in the treatment of Chinese patients with refractory or relapsed acute leukemia.

Adult↗

PubMedDate not supplied

Concomitant renal cell carcinoma and metastatic epithelioid angiosarcoma with microangiopathy.

Epithelioid angiosarcoma is an extremely rare clinical entity. Recognized only in recent years, epithelioid angiosarcoma mimicks epithelial tumors, both morphologically and immunohistochemically. It is very aggressive, assuming a rapid, metastatic and fatal course. This is a report of a case with an unequivocal diagnosis of epithelioid angiosarcoma and concomitant renal cell carcinoma. Reports of cancer with double origins of this combination, in patients without inherited von Hippel-Lindau disease, are extremely rare in the English literature. A review of the literature encompassing all cases of epithelioid angiosarcoma since 1983 is included.

Adult↗

PubMedDate not supplied

Mushroom poisoning in children: report of an accident.

There were very few cases of mushroom poisoning every year in Taiwan and yet no fatal incident have been reported. A species named Amanita phalloides had high lethality rate (22-33%). Physicians should be aware of it's toxic property and be able to treat the patient in case of mushroom poisoning. However, mycologist sometimes might not distinguish edible from toxic mushroom so that educating people not to ingest wild mushroom is very important. We present 4 children with gastrointestinal syndrome after ingesting wild mushroom. We also introduce some basic approaches in treating mushroom poisoning in this paper.

Accidents, Home↗

PubMedDate not supplied

Increased NM23: MTS1 ratio inversely correlated with metastasis behaviour in human lung squamous cell carcinoma.

The nm23 and mts1 genes have been the focus of attention as regards the association of their expression with metastatic behaviour. The level of nm23 and mts1 gene products has been demonstrated to correlate with metastatic potential in some tumors, but not in all. Here we show that these two genes might be coregulated and the ratio of their expression correlated with metastatic behaviour. Western blot analysis showed that the expression of both NM23 and MTS1 proteins was reduced in human lung cancer CH27 cells by retinoic acid treatment, but the ratio of NM23: MTS1 increased in a dose-dependent manner. Results also exhibited that retinoic acid altered the microtubule assembly of CH27 cells and reduced the metastatic ability of the cells in vitro. These data suggest that the metastatic potential of CH27 cells may be related to the relative expression of these two genes, and that their pathway in regulating metastatsis might be linked.

Carcinoma, Squamous Cell↗

PubMedDate not supplied

Concomitant chemotherapy and radiotherapy for locally advanced nasopharyngeal carcinoma.

BACKGROUND: The prognosis of stage III and IV nasopharyngeal carcinoma treated with radiation therapy alone is poor. To improve outcome, concomitant chemotherapy was incorporated into the treatment of locally advanced nasopharyngeal carcinoma. METHODS AND PATIENTS: Seventy-four patients with locally advanced nasopharyngeal carcinoma were prospectively treated with a combination of concomitant chemotherapy and computerized-tomography-assisted radiotherapy at Koo Foundation Sun Yat-Sen Cancer Center, Taipei, Taiwan, between April 1990 and December 1995. The first 29 patients who had a minimum of 2 years of follow-up were included in this report. Their median interval of follow-up was 42 months. The dose of radiation was 7000 cGy given in 35 fractions. Two courses of chemotherapy, consisting of cisplatin and 5-fluorouracil, were delivered simultaneously with radiotherapy during weeks 1 and 6, and two additional monthly courses were given after radiotherapy. Included in this study were four patients with stage III and 25 patients with stage IV disease. RESULTS: Toxicities of concomitant radiotherapy and chemotherapy were acceptable and reversible. The locoregional control rate at 50 months was 88.2%, and the disease-free survival rate was 74.6%. DISCUSSION: Our results demonstrate an improved survival with the addition of computerized tomography treatment planning and concomitant chemotherapy to radiotherapy in the treatment of locally advanced nasopharyngeal carcinoma when compared with data in the current literature. However, a randomized trial comparing computerized-tomography-assisted radiotherapy with and without chemotherapy is necessary to confirm the contribution of chemotherapy.

Adult↗

PubMedDate not supplied

The removal index for evaluation of dialysis.

OBJECTIVES: To find an index of adequacy that takes into consideration the effect of the decreasing concentration of urea nitrogen in hemodialysis (HD) and can be used before treatments to quantitate the prescriptions with the same criterion for both HD and continuous ambulatory peritoneal dialysis (CAPD). DESIGN: The removal index was obtained through mathematical theories and then compared with the urea index (KT/V) values of the sample patients. PATIENTS: Thirty-two HD and 21 CAPD patients were included. All patients were dialyzed with optimal urea index values and had been stable for at least one year. RESULTS: The removal index in HD (xi HD) for each dialysis was O.62 +/- 0.07, and the normalized removal index in CAPD (xi CAPD) was 0.59 +/- 0.11. There was no statistical significance. This result is consistent with the fact that no difference of morbidity or mortality exists between these two modalities. CONCLUSION: After mathematical manipulation, the removal index in HD can be presented in the form of the urea reduction ratio, which is a retrospective measure to estimate the performance of hemodialysis. This study implies that the removal index is able to facilitate the prescriptions for adequate dialysis. The removal index can also be used to explain the reason why the urea index values are always larger in HD than in CAPD.

Adult↗