Biomedical subjects
Publications and source records attributed to Y Xue.
This paper reports the isolation of eleven compounds from the roots of Ostericum grosseserratum, of which nine compounds were elucidated as myristic acid, palmitic acid, stearic acid, octacosanoic acid, succinic acid, beta-sitosterol, sitosterol-beta-D-glucoside, isoscopletin and sucrose. The results are helpful in the study of plant taxonomy.
The present study provides evidence that green tea extract (GTE), consisting of polyphenol components, is a highly active nucleoside transport inhibitor. GTE markedly inhibited radiolabeled thymidine and uridine transport in mouse leukemia L1210 cells, with IC50 values of 3.2 and 8.0 mumol/L, respectively. GTE blocked the rescue effect of exogenous nucleosides and enhanced the cytotoxicity of AraC and MTX to L1210 cells and human hepatoma BEL-7402 cells. GTE markedly potentiated the inhibitory effect of AraC on leukemia L1210 and P388 in mice. These results indicate that GTE is potentially useful when combined with antimetabolites in cancer chemotherapy.
This report describes the changes of serum Ca, P, ALP and 25-OH D3 (using protein binding assay) with age in 592 normal Beijing subjects, aged 0-87 years old. The results were: (1) There was highly negative correlation between age and 25-OH D3 (r = -0.380, P less than 0.01), especially after 41 years old, less between age and ALP and least with P and Ca. (2) There was a significant sex difference of 25-OH D3 and ALP (P less than 0.05). Their serum levels were higher in the male than in the female, indicating that the female is easier to suffer from metabolic bone disease than the male after 41 years of age. (3) There was a distinct seasonal variation in serum 25-OH D3 levels, which were lower in winter and Spring than in Summer and Autumn (P less than 0.001), indicating that there is a greater possibility of Vitamin D deficiency in Winter and Spring.
The composition and the size of proteoglycans (PGs) and glycosaminoglycans (GAGs) from femoral head cartilage of different age were determined by caesium chloride density gradient centrifugation, sepharose chromatography and chemical analysis. The results showed that the size of PG subunits from articular cartilage decreases with increasing age. In PGs and GAGs from cartilage, uronic acid and galactosamine content decreased; the ratio of in keratin sulphate to chondroitin sulphate increased; glucosamine and hydroxyproline content decreased with age The cause of degenerative changes and the measures to prevent and treat them are discussed.
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A shuttle plasmid vector, pSE-3 was constructed using the Streptomyces plasmid pIJ486 and E. coli plasmid pGEM-3 digested with BgIII and BamHI respectively. The shuttle plasmid pSE-3 could replicate and express its neomycin resistance in both Streptomyces and E. coli well. The pSE-3 has opposed promoters containing bacteriophage ST6 and T7, the restriction enzyme digestion showed that the pSE-3 has a single site with HindIII and EcoRI respectively, it is very useful for the cloning and expression of the valuable gene inserts. The pSE-3 is stable in both of Streptomyces and E. coli after re-transformed pSE-3 is re-transformed from Streptomyces into E. coli and some 50 generations are propagated.
Headaches of the neurofunctional type, blood vascular type, neuro-vascular type, and musculotonic type are commonly encountered clinically. The authors report a nasal inhalant of Chinese herbal drugs which has been effective in the treatment of these varieties of headache.
Postburn changes in serum levels of Alterations in serum Calcium (Ca), Phosphates (Pi), alkaline-phosphatase (ALP), calcitonin (CT), parathyroid hormone (PTH) and 25-hydroxy Vitamin D (25 OHD) levels in 14 burn patients were studied. The results indicated: (1) Hypocalcemia and hypophosphatemia occurred during burn shock. Hypocalcemia was closely associated with the degree of burn and patient's condition. (2) Serum CT and PTH levels were significantly increased in severe burn patients compared with controls on day 1. Then the parameters tended to decrease to normal levels. (3) CT/Ca ratio or CT/Pi ratio might be a sensitive index to indicate the degree of burn and patient's condition.
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A series of electron micrographs showing the presence of different molecular forms representing various replication stages of plasmid deoxyribonucleic acid from Streptomyces griseus was obtained. Based upon an analysis of these electron micrographs, a tentative model for plasmid deoxyribonucleic acid replication in S. griseus is proposed.
Statistical-learning methods have been developed for facilitating the prediction of pharmacokinetic and toxicological properties of chemical agents. These methods employ a variety of molecular descriptors to characterize structural and physicochemical properties of molecules. Some of these descriptors are specifically designed for the study of a particular type of properties or agents, and their use for other properties or agents might generate noise and affect the prediction accuracy of a statistical learning system. This work examines to what extent the reduction of this noise can improve the prediction accuracy of a statistical learning system. A feature selection method, recursive feature elimination (RFE), is used to automatically select molecular descriptors for support vector machines (SVM) prediction of P-glycoprotein substrates (P-gp), human intestinal absorption of molecules (HIA), and agents that cause torsades de pointes (TdP), a rare but serious side effect. RFE significantly reduces the number of descriptors for each of these properties thereby increasing the computational speed for their classification. The SVM prediction accuracies of P-gp and HIA are substantially increased and that of TdP remains unchanged by RFE. These prediction accuracies are comparable to those of earlier studies derived from a selective set of descriptors. Our study suggests that molecular feature selection is useful for improving the speed and, in some cases, the accuracy of statistical learning methods for the prediction of pharmacokinetic and toxicological properties of chemical agents.
P-glycoproteins (P-gp) actively transport a wide variety of chemicals out of cells and function as drug efflux pumps that mediate multidrug resistance and limit the efficacy of many drugs. Methods for facilitating early elimination of potential P-gp substrates are useful for facilitating new drug discovery. A computational ensemble pharmacophore model has recently been used for the prediction of P-gp substrates with a promising accuracy of 63%. It is desirable to extend the prediction range beyond compounds covered by the known pharmacophore models. For such a purpose, a machine learning method, support vector machine (SVM), was explored for the prediction of P-gp substrates. A set of 201 chemical compounds, including 116 substrates and 85 nonsubstrates of P-gp, was used to train and test a SVM classification system. This SVM system gave a prediction accuracy of at least 81.2% for P-gp substrates based on two different evaluation methods, which is substantially improved against that obtained from the multiple-pharmacophore model. The prediction accuracy for nonsubstrates of P-gp is 79.2% using 5-fold cross-validation. These accuracies are slightly better than those obtained from other statistical classification methods, including k-nearest neighbor (k-NN), probabilistic neural networks (PNN), and C4.5 decision tree, that use the same sets of data and molecular descriptors. Our study indicates the potential of SVM in facilitating the prediction of P-gp substrates.
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In this study, we describe rat NK cell-derived MMPs including membrane-type MMPs (MT-MMPs) and tissue inhibitors of MMP (TIMPs). RT-PCR analysis from cDNA of rat A-NK cells revealed mRNA for MMP-2, MMP-9, MMP-7, MMP-10, MMP-11, MMP-13, MT1-MMP, MT2-MMP, TIMP-1, and TIMP-2. The RNK-16 cells expressed mRNA for MMP-7, MMP-10, MMP-11, MT1-MMP, MT2-MMP, TIMP-1, and TIMP-2, in addition to MMP-3 and MMP-13. Western blot analysis confirmed proteins for MT1-MMP and MT2-MMP in RNK-16 cells. TIMP-1 in rat A-NK cells was present at molecular mass of 34-kDa protein which may represent a highly glycosylated form. Genistein, a natural isoflavone found in soybeans, inhibited proliferation of RNK-16 cells in dosage dependent manner. In addition, it down-regulated the expression of MMP-13, MT1-MMP, TIMP-1 and TIMP-2. Moreover, genistein greatly impaired the ability of RNK-16 cells to invade through a model basement membrane. This effect might be mediated by the observed down-regulation of MMP-13 and MT1-MMP.
We have previously investigated the role of the urokinase plasminogen activator (uPA) system in NK cell invasion. We have also studied NK cell-derived matrix metalloproteinases (MMPs) in extracellular matrix (ECM) degradation. We now report that both enzyme systems cooperate in NK cell invasion. Zymographic analyses detected uPA in RNK-16 cell conditioned media (CM) with the same molecular weights as the uPA we have previously shown to be associated with the rat NK cell urokinase plasminogen activator receptor. The combination of aprotinin, an inhibitor of plasmin, and Batimastat (BB94), an inhibitor of MMPs, in Matrigel invasion assays showed a more potent inhibitory effect on NK cell invasion than either inhibitor alone. Finally, a down regulation of uPA mRNA was noted following RNK-16 stimulation with collagen IV, fibronectin, and laminin.