Determination and estimation of aqueous solubilities and n-octanol/water partition coefficients for phenylacrylates.
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1-Octanol↗
Biomedical subjects
L S Wang
Publications and source records attributed to L S Wang.
Joint QSAR analysis using the Free-Wilson approach and quantum chemical parameters.
A new quantitative structure-activity relationship (QSAR) technique combining the Free-Wilson method and constructed quantum chemical parameters was used to simulate the aqueous solubility (Sw), 1-octanol/water partition coefficient (Kow) of 14 new synthesized benzanilide derivatives and their 96 h acute toxicity (EC50) to Daphnia magna. The mode of action of the 14 selected compounds to Daphnia magna was shown to be a complex process involving a physical partition stage and a bio-chemical reaction stage. The results also indicated that the joint (QSAR) analysis was much effective than the original Free-Wilson method and Hansch method not only in predicting properties/toxicity, but also in investigating the mode of action of chemicals.
1-Octanol↗
Ultrasonic destruction of chloroform and carbon tetrachloride in aqueous solution.
The sonochemical destruction of binary mixtures of chloroform and carbon tetrachloride in aqueous solution at 30 kHz has been studied. The influences of initial concentration, bicarbonate/chloride, and acoustical intensity on the destruction rates have been observed. It was found that the destruction of the two compounds appeared to follow pseudo-first-order reaction kinetics with the current experimental concentration range. The rate constant of chloroform for initial concentration as high as 100.4 mg/L decreased compared to initial concentration 36.13 micrograms/L, when the rate constants of carbon tetrachloride hardly changed. However, their destruction rates increased with increasing acoustical intensity and were independent of addition of bicarbonate or chloride. The resulting yield of ionic product (Cl-) for chloroform was determined.
Carbon Tetrachloride↗
New approaches for reconstructing phylogenies from gene order data.
We report on new techniques we have developed for reconstructing phylogenies on whole genomes. Our mathematical techniques include new polynomial-time methods for bounding the inversion length of a candidate tree and new polynomial-time methods for estimating genomic distances which greatly improve the accuracy of neighbor-joining analyses. We demonstrate the power of these techniques through an extensive performance study based on simulating genome evolution under a wide range of model conditions. Combining these new tools with standard approaches (fast reconstruction with neighbor-joining, exploration of all possible refinements of strict consensus trees, etc.) has allowed us to analyze datasets that were previously considered computationally impractical. In particular, we have conducted a complete phylogenetic analysis of a subset of the Campanulaceae family, confirming various conjectures about the relationships among members of the subset and about the principal mechanism of evolution for their chloroplast genome. We give representative results of the extensive experimentation we conducted on both real and simulated datasets in order to validate and characterize our approaches. We find that our techniques provide very accurate reconstructions of the true tree topology even when the data are generated by processes that include a significant fraction of transpositions and when the data are close to saturation.
Biological Evolution↗
Influence of whole peptidoglycan of bifidobacterium on cytotoxic effectors produced by mouse peritoneal macrophages.
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Animals↗
Predicting octanol/water partition coefficient using solvation free energy and solvent-accessible surface area.
The regression model for octanol/water partition coefficients (Kow), is founded with only two molecular descriptors available through quantum chemical calculations: solvation free energy (delta Gs), and solvent-accessible surface area (SASA). For the properties of 47 organic compounds from 17 types, the model gives a correction coefficient (adjusted for degrees of freedom) of 0.959 and a standard error of 0.277 log unit. It is a suitable way to predict the partition properties that are related to solute-solvent interactions in the water phase.
Kinetics↗
Development of quantitative structure activity relationships in toxicity prediction of complex mixtures.
AIM: To predict the toxicity of mixtures of halogenated benzenes (narcotics). METHODS: Acute toxicity test of single chemicals and mixtures was performed using Photobacterium phosphoreum. Partition coefficients of mixtures were calculated by a special equation. Quantitative structure-activity relationship (QSAR) studies were carried out based on results of toxicity tests, n-octanol/water partition coefficient (Kow), and partition coefficient of mixtures (Kmix). RESULTS: 1) There was a good relationship between toxicity and lgKow for single compounds. 2) QSAR analysis showed a perfect correlation between the calculated Kmix and the mixture toxicity for binary mixtures. 3) Using the QSAR model of binary mixtures, the toxicity of other related mixtures containing different composition and fraction was predicted very well. CONCLUSION: The toxicity of halogenated benzene mixtures (narcotics) was predicted by QSAR. This kind of study is helpful for assessing the toxicity of narcotic mixtures.
Benzene Derivatives↗
Effects of CYP2C19 genotype and CYP2C9 on fluoxetine N-demethylation in human liver microsomes.
AIM: The present study was designed to define the kinetic behavior of fluoxetine N-demethylation in human liver microsomes and to identify the isoforms of cytochrome P-450 (CYP) involved in this metabolic pathway. METHODS: The kinetics of Ne formation of norfluoxetine was determined in human liver microsomes from six genotyped CYP2C19 extensive metabolizers (EM). The correlation studies between the fluoxetine N-demethylase activity and various CYP enzyme activities were performed. Selective inhibitors or chemical probes of various cytochrome P-450 isoforms were also employed. RESULTS: The kinetics of norfluoxetine formation in all liver microsomes were fitted by a single-enzyme Michaelis-Menten equation (mean Km=32 micromol/L+/-7 micromol/L). Significant correlations were found between N-demethylation of fluoxetine at both 25 micromol/L and 100 micromol/L and 3-hydroxylation of tolbutamide at 250 micromol/L (r1=0.821, P1=0.001; r2=0.668, P2=0.013), respectively, and S-mephenytoin 4'-hydroxylase activity (r=0.717, P=0.006) at high substrate concentration of 100 micromol/L. S-mephenytoin (SMP) (a CYP2C19 substrate) at high concentration and sulfaphenazole (SUL) (a selective inhibitor of CYP2C9) substantially inhibited norfluoxetine formation. The reaction was minimally inhibited by coincubation with chemical probe, inhibitor of CYP3A4 (triacetyloleandomycin, TAO). The inhibition of fluoxetine N-demethylation at high substrate concentration (100 micromol/L) was greater in PM livers than in EM livers (73 % vs 45 %, P < 0.01) when the microsomes were precoincubated with SUL plus TAO. CONCLUSION: Cytochrome P-450 CYP2C9 is likely to be a major CYP isoform catalyzing fluoxetine N-demethylation in human liver microsomes at a substrate concentration close to the therapeutic level, while polymorphic CYP2C19 may play a more important role in this metabolic pathway at high substrate concentration.
Aryl Hydrocarbon Hydroxylases↗
Role of cytochrome P450 in estradiol metabolism in vitro.
AIM: Catechol estrogens and 16alpha-hydroxy estrogen are important metabolites that cause carcinogenesis. This study was aimed to stud y the role of cytochrome P450 in estradiol metabolism. METHODS: The estradiol metabolites were determined with HPLC-ECD. Correlation of estradiol metabolites production between cytochrome P450 activity, the inhibitory effect of specific inhibitors and enzyme catalyzing kinetics were studied in cDNA-expressed P450 or human liver microsomes. RESULT: CYP1A2, CYP3A4, and CYP2C9 catalyze the estradiol 2-hydroxylation. CYP2C9, CYP2C19, and CYP2C8 have high activity in catalyzing 17beta-hydroxy dehydrogenation in cDNA expressed P450, but CYP1A2 is the most important enzyme in catalyzing estradiol 2-hydroxylation. Using furafyllin and troleandomycin to inhibit CYP1A2 and CYP3A4 in liver microsomes, it was found that the 2-hydroxylation had been inhibited about the same amount. This result suggests that in human liver microsomes CYP1A2 and CYP3A4 play an important role in 2-hydroxy estradiol formation. At low substrate concentration, 17beta -hydroxy dehydrogenation dominated the estradiol metabolism, but at high substrate concentration, 2-hydroxylation exceeded 17beta-hydroxy dehydrogenation to become the important mechanism. CONCLUSION: CYP1A2 and CYP3A4 are two important enzymes catalyzing the main estradiol 2-hydroxylation metabolism pathway at high substrate concentrations. 17beta-hydroxy dehydrogenation is the main metabolism pathway at low concentrations, and CYP2C9, CYP2C19, and CYP2C8 may have high catalyzing activity.
Adult↗
Interindividual variations in levels and activities of cytochrome P-450 in liver microsomes of Chinese subjects.
AIM: To compare the level and/or activity of several important cytochrome P-450 (CYP) enzymes in liver microsomes prepared from different Chinese subjects. METHODS: Individual CYP contents, including CYP1A2, CYP2C9, and CYP3A4, in liver microsomes of 17 Han, 17 Zhuang, and 8 Miao subjects were determined by using Western blot analysis and densitometric scanning. The substrates for measuring the activity of individual CYP in vitro included phenacetin, tolbutamide, debrisoquine, and omeprazole. RESULTS: There was a large interindividual variability in the content and activity of CYP1A2, 2C9 and 3A4. And the activity of CYP2D6 also varied greatly between individual samples. CYP3A4 (32 %) is the most abundant CYP in Chinese liver microsomes, and the levels of CYP2C9 (19 %) and CYP1A2 (16 %) were also considerable. No clear ethnic, sex- and age-related differences in individual CYP content and catalytic activity were detected in 42 Chinese liver samples, except that there were somewhat ethnic and sex-related differences in the content and activity of CYP1A2. Good correlation between enzyme protein content and activity was found for CYP1A2, 2C9 and 3A4. CONCLUSION: Our results may provide useful information for the study of drug metabolism by liver microsomes in Chinese.
Aryl Hydrocarbon Hydroxylases↗
Effects of polyamines on organogenesis and somatic embryogenesis of Lycium barbarum calli.
Levels of three endogenous free polyamines (PAs), Put, Spd and Spm, were detected during organogenesis and somatic embryogenesis (SE) of Lycium barabrum (L.) calli. The predominant forms of PAs in organogenesis and SE were found to be Put and Spd, respectively. In both developmental pathways, the changes of Put content were very similar, i.e., it accumulated quickly in the initial stages of calli differentiation and then decreased; with the further morphogenesis, increase in Put level was also observed. The highest level of Spd was obtained at day 1 of calli organogenesis; while, after 1 day of culture for calli SE, Spd level began to increase and reached a maximum at day 10. The treatments with exogenous PAs had positive effects on both organogenesis and SE, especially those of Spd on organogenesis and SE and Put on SE. However, Put showed no effects on adventitious bud formation. CHA, which inhibits the activity of Spd synthetase, prevented both adventitious bud formation and further development of somatic embryo into plantlet. Although MGBG, a specific inhibitor of S-adenosyl methionine decarboxylases, had little effects on organogenesis, it reduced the number of somatic embryo and the plantlets subsequently regenerated. Such inhibitions could be reversed by Spd (50 mumol/L). These results from organogenesis and SE of the same specie indicate that PAs influenced these two in vitro morphogenesis pathways.
Lycium↗
(MgO)(-)(n) (n = 1-5) clusters: multipole-bound anions and photodetachment spectroscopy.
Photoelectron spectra of (MgO)(-)(n) (n = 1-5) reveal a surprising trend: The electron binding energy decreases from n = 1 to 4, and then increases from 4 to 5. Ab initio calculations suggest this pattern is related to the electrostatic interaction between the extra electron and the charge distribution of the neutral cluster. This interaction is significant in MgO (-) and (MgO)-5, for which the lowest nonvanishing multipole moment (LNM) is a dipole; it is smaller for (MgO)-2 and (MgO)-3, for which a quadrupole is the LNM; and it is the smallest for (MgO)-4, for which an octopole is the LNM. The cubic (MgO)-4 is the first octopole-bound anion yet observed experimentally and characterized theoretically.
Journal Article↗
Resectional treatment for thyroid cancer with tracheal invasion: a long-term follow-up study.
HYPOTHESIS: Transmural invasion of the trachea by well-differentiated thyroid carcinomas is a locally advanced disease condition. It frequently causes deaths owing to airway obstruction. We hypothesized that resection of the invaded trachea followed by primary anastomosis provides the opportunity for cure. DESIGN: A retrospective review study of medical records. SETTING: The surgical department of a tertiary referral center. PATIENTS: Eight patients with well-differentiated thyroid carcinomas, complicated with tracheal invasion resulting in bleeding and airway obstruction, operated on by tracheal resection and immediate anastomosis, were included. INTERVENTIONS: All patients received total thyroidectomy and neck lymph node dissection as well as segmental tracheal resection followed by primary reconstruction. Postoperative radioactive sodium iodine I 131 treatment and suppression therapy with thyroxine were applied to all of them. MAIN OUTCOME MEASURE: Postoperative follow-up of serum levels of human thyroglobulin and abnormal radioactive iodine 131I from whole body scan. RESULTS: Seven patients are alive. Of these patients, 5 had no evidence of disease: (3 had no evidence of cancer for more than 10 years' follow-up), 2 had regional lymph node metastasis, and 1 had lung metastases. The remaining patient had anastomotic site recurrence with airway obstruction and needed tracheostomy to relieve stridor. She was lost to follow-up 39 months after undergoing the initial operation. CONCLUSIONS: Patients with mucosal invasion of the trachea by well-differentiated thyroid carcinomas should be treated by surgical resection followed by primary reconstruction when technically feasible. This facilitates postoperative care, and it is possible to achieve long-term survival with improvement of the quality of life and possible cures.
Adult↗
Postreperfusion syndrome in orthotopic liver transplantation.
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Adult↗
Biochemical responses of the mycorrhizae in Pinus massoniana to combined effects of Al, Ca and low pH.
Biochemical responses of Pinus massoniana, with and without the inoculation mycorrhizal fungus Pisolithus tinctorius at the root, to artificial acid rain (pH 2.0) and various Ca/Al ratios were investigated. Some enzymes associated with the nutritive metabolism, such as acid phosphatase, alkaline phosphatase, nitrate reductase, mannitol dehydrogenase and trehalase, in the roots, stems and leaves of plant were obviously inhibited by the artificial acid rain and Al. After treatment with pH 2.0 + Ca/Al (0/1 or 1/10) artificial acid rain, the protein content in the organs was decreased. However, the activities of superoxide dismutase (SOD) and peroxidase (POD) and glutathione (GSH) concentrations were induced. It demonstrated that acid rain and Al could induce oxygen radicals in plant. Compared with the treatments with lower pH or Al, respectively, the combination of lower pH and Al concentration was more toxic to P. massoniana. Al toxicity could be ameliorated by the addition of Ca and the amelioration was the most when the ratio was 1/1 among the various Ca/Al ratio. Infection with mycorrhizal fungus P. tinctorius at the root of P. massoniana increased the ability of the plant to resist the toxicity of artificial acid rain and Al stress.
Acid Phosphatase↗
Polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River.
The contamination levels of polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River (Nanjing part) were analyzed in this paper. Their concentrations determined by GC/MS were very low in comparison with those in European River. The average concentration of total HCH (alpha-HCH, beta-HCH, gamma-HCH) was much higher than that of other PCOCs in all waters, which made up 65% of total amount of PCOCs. Due to the complete dilution and mixture of pollutants in the mighty Yangtse River, the content of PCOCs at each sampling station demonstrated very similar spatial pattern for waters and suspended solids. Since the small suspended solid (<0.7 microm) passed through the filter was also considered as dissolved part, the dominant parts of HCHs, PCA and PCBs were found in dissolved phase with percentage proportion of 85-94%, 72-85% and 61-78%, respectively. For DDTs, HCB and PeCB, their contents in dissolved phase were slightly higher than in particulate phase. The contents of PCOCs in sediments were also very low and varied with high fluctuation at different sampling points, indicating the heterogeneous deposition. HCB and its metabolite (PeCB) presented the highest contamination levels among PCOCs in sediments.
Anisoles↗
Expression and activation of caspase-3/CPP32 in CD34(+) cord blood cells is linked to apoptosis after growth factor withdrawal.
Caspase-3/CPP32, a member of the interleukin-1 converting enzyme (ICE) family, is considered an executioner protease in mammalian cells during apoptosis. Although expression and activation of caspase-3/CPP32 protein have been studied in many tissues and leukemia cell lines, this has not been explored in primitive hematopoietic CD34(+) cells. In this study, we evaluated expression and activation of caspase-3/CPP32 protein in CD34(+) cells from cord blood (CB) during apoptosis induced by growth factor deprivation. Reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot, and flow cytometry analysis were used in this study to determine the expression of caspase-3/CPP32 in CD34(+) CB cells during apoptosis. Our results demonstrated that caspase-3/CPP32 mRNA was constitutively expressed at a very low level in freshly isolated CD34(+) cells. Expression of caspase-3/CPP32 mRNA and protein was upregulated when these cells were first expanded in suspension culture with growth factors for 3 days. However, only the 32 kDa inactive caspase-3/CPP32 proenzyme was detected in the freshly isolated CD34(+) cells and after 3 days expansion with cytokines. Within 12 hours after growth factor withdrawal from expanded cells caspase-3/CPP32 was activated and a cleavage 20 kDa protein was detected; a poly(ADP-ribose) polymerase (PARP) was cleaved by activated caspase-3/CPP32. Activation of caspase-3/CPP32 and apoptosis upon growth factor withdrawal were inhibited/reduced by the caspase inhibitors, z-VAD-fmk and DEVD-CHO. These results demonstrate that caspase-3/CPP32 is involved in apoptosis of primitive CB CD34(+) cells but may not be the only mechanism involved.
Antigens, CD34↗
Expression of fas ligand on bile ductule epithelium in biliary atresia--a poor prognostic factor.
PURPOSE: The aim of this study was to investigate the possible role of Fas and Fas ligand system in biliary atresia. METHODS: Immunohistochemical stains of Fas and Fas ligand (FasL) and in situ hybridization of Fas ligand messenger RNA (mRNA) were performed on paraffin-embedded liver specimens of 36 biliary atresia, 6 choledochal cysts, and 14 nontumorous parts of pediatric liver tumors. Apoptosis was detected by terminal deoxynucleotidyl transferase deoxy-UTP nick end labeling (TUNEL). The grade of liver fibrosis and results of bile drainage on the patients with biliary atresia were compared with the results of FasL expression. RESULTS: Fas protein was positive on the hepatocytes and bile ductule epithelia of all the livers examined and also positive on some monocytes around the portal area in all the biliary atresia patients. FasL protein was positive on bile ductule epithelia in 10 biliary atresia patients and also positive on some monocytes in most of the biliary atresia patients. Positive signals of FasL mRNA were noted on hepatocytes in 4 biliary atresia, bile ductule epithelia in 19 biliary atresia patients, and some monocytes in most of the biliary atresia patients. Apoptotic nuclei were present among monocytes in all the biliary atresia livers but present among bile ductule epithelia only on the BA with positive FasL mRNA signals on ductule epithelium. The fibrosis grade was similar between biliary atresia with positive FasL mRNA signals and negative signals. The bile drainage was better in the biliary atresia without positive FasL mRNA signals. CONCLUSIONS: Fas ligand expression on bile ductule epithelia in biliary atresia may be induced to counterattack the infiltrating lymphocytes. Although the factors for post-Kasai bile drainage are multiple, the authors suggest Fas ligand expression on bile ductule epithelia may be a poor prognostic factor by playing a role in the continuous damage and obliteration of intrahepatic bile ducts after Kasai operation.
Base Sequence↗