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H Wang

Publications and source records attributed to H Wang.

At least 739 records · Page 41Linked to original sources
PubMed2000

Efficient production of ground-state potassium molecules at sub-mK temperatures by two-step photoassociation

We have developed a two-step " R-transfer" method that efficiently produces translationally ultracold potassium molecules in the X (1)Sigma(+)(g) electronic ground state. Laser-cooled atoms are initially photoassociated at large internuclear separation R to form molecules in high vibrational levels of the 1 (1)Pi(g) state, which are in turn excited by an additional laser to shorter-range Rydberg states such as 5 (1)Pi(u) and 6 (1)Pi(u). Subsequent radiative decay produces ground-state molecules at rates up to 10(5) molecules/second per vibrational level.

Journal Article↗
PubMed2000

Electron impact mass spectral fragmentation patterns of 2a,4-disubstituted 5-benzoyl-2-chloro-2a,3,4,5-tetrahydroazeto[1,2-a][1,5]benzodiazepin-1( 2H)-ones.

The mass spectrometric behaviour of six 2a,4-disubstituted 5-benzoyl-2-chloro-2a,3,4,5-tetrahydroazeto[1,2-a][1,5]benzodia zepin-1(2H)-ones has been studied with the aid of mass-analysed ion kinetic energy spectrometry and accurate mass measurements under electron impact ionization. All compounds show a tendency to eliminate a chlorine atom, a chlorine atom plus benzaldehyde, benzoyl radical, chloroketene or chlorine atom plus CO and H2O molecules to yield, respectively, [M-Cl]+ ions, 2a,4-disubstituted 2a,3-dihydroazeto[1,2-a][1,5]benzodiazepin-1(2H)-one ions, [M-PhCO]+ ions, 2,4-disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions, or 1,2,4-trisubstituted 1H-1,7-benzodiazonine ions, which could also be formed from [M-Cl]+ ions by loss of CO and H2O molecules simultaneously. The [M-Cl]+ ions could further lose benzoyl radical to form [M-Cl-PhCO]+ ions, or lose benzoyl amide and undergo a rearrangement to form 4,6-disubstituted 1-benzoazocine-2(1H)-one ions. The [M-PhCO]+ ions could eliminate NH to produce 2a,4-disubstituted 2,2a,3,4-tetrahydroazeto[1,2,-a]quinolin-1-one ions, which could further eliminate chloroketene, CO and/or HCl to produce some important ions, respectively. 2,4-Disubstituted 1-benzoyl-2,3-dihydro-1H-1,5-benzodiazepine ions could lose benzoyl radical to yield 2,4-disubstituted 2,3-dihydro-1H-1,5-benzodiazepine ions, which could further yield other small fragment ions by loss of propene/styrene or small fragments.

Benzodiazepinones↗
PubMed2000

Detection of oxidative species for 4-phenoxyphenol derivatives during the electrospray ionization process.

Analyses by flow injection as well as liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS) were performed with four 4-phenoxyphenol derivatives. When ambient temperature nitrogen gas was used to facilitate solvent evaporation, [M + H]+, [M + NH4]+, and [2M + NH4]+ ions were observed as the major ions. As the nitrogen gas temperature increased from ambient to 250 and 450 degrees C, [M]+*, [M - 1]+ and [M + 15]+ ions were the predominant ions. Heat-induced oxidation was found to be the primary source for the formation of oxidative species. Aqueous solvents were found to be essential for the formation of the [M + 15]+ ions. The [M]+* and [M + 15]+ ions were further characterized by tandem mass spectrometry. Based on the MS/MS data, it was proposed that the [M + 15]+ ions were the in-source generated 1,2-quinone ions.

Mass Spectrometry↗
PubMed2000

Determination of resibufogenin and cinobufagin in heart-protecting musk pill by HPLC.

A high-performance liquid chromatographic (HPLC) method for the simultaneous determination of resibufogenin and cinobufagin in traditional Chinese medicine (heart-protecting musk pill, shexiang baoxin wan in Chinese) was developed. A reversed-phase system with a Hypersil (ODS2) C(18) column and tetrahydrofuran: methanol: water (8:31:61) mobile phase was employed for the separation of resibufogenin and cinobufagin. The detection was set at 299 nm and ethinyl estradiol was chosen as the internal standard. The limit of detection was 1.5 ng for resibufogenin and 2.0 ng for cinobufagin at a signal-to-noise ratio of 4:1. It is a rapid, simple and accurate method for quantitative analysis of resibufogenin and cinobufagin in heart-protecting musk pill.

Bufanolides↗
PubMed2000

Significance of protein kinase CK2 nuclear signaling in neoplasia.

Many stimuli play a role in influencing the structure and function of chromatin and nuclear matrix through post-translational modifications of the component proteins in these dynamic structures. We propose that the protein serine/threonine kinase CK2 (formerly casein kinase II) is one such agent that is involved in signal transduction in the nuclear matrix and chromatin in response to a variety of stimuli. Protein kinase CK2 appears to undergo rapid modulations in its association with nuclear matrix and nucleosomes in response to mitogenic signals and is involved in the phosphorylation of a variety of intrinsic proteins in these structures depending on the state of genomic activity. In addition, its association or loss from the nuclear matrix may also influence the apoptotic activity in the cell. CK2 has been found to be dysregulated in virtually all the neoplasias examined and nuclear association appears to be an important facet of its expression in tumor cells. We hypothesize that CK2 provides a functional paradigm linking the nuclear matrix and chromatin structures. Identification of precise loci of action of CK2 in these structures and how they influence the morphological appearance of the nucleus under normal and abnormal growth conditions would be an important future direction of investigation. J. Cell. Biochem. Suppl. 35:130-135, 2000. Published 2001 Wiley-Liss, Inc.

Animals↗
PubMed2000

Alkaline treatment of the cellulose fiber affecting membrane column behaviour for high-performance immunoaffinity chromatography.

The original cellulose fibers and those treated by alkaline solution were both used to prepare the acrylic membranes. The two kinds of membranes were packed into the columns for high-performance immunoaffinity chromatography by the immobilization of protein A on them. It was observed that the alkaline treatment of the cellulose fiber decreased the pressure resistance of the membrane to the mobile phases and greatly increased the accessible volume to the proteins, but affected the adsorption capacity of human IgG on the protein A membrane columns less. There is little difference between those two kinds of membranes on the adsorption capacities of HIgG, which means that the alkaline treatment of the cellulose fiber only significantly changes the void volume inter-membrane, and the porosity and surface area of membrane less. Alkaline treatment of the cellulose fiber reduced the membrane-column efficiency significantly. Some typical examples for the immunoaffinity analysis of IgG from human and dog plasma on the protein A membrane columns are illustrated.

Alkalies↗
PubMed2000

Synthesis and characteristics of the human serum albumin-triazine chiral stationary phase.

Human serum albumin (HSA) was successfully bonded to silica with s-triazine as activator. The coupling reaction by this method was rapid and effective. The triazine-activated silica is relatively stable and can be installed for at least 1 month without obvious loss of reactivity when stored below 30 degrees C, pH below 7. It was observed that the amount of bound HSA reached 120 mg/g silica calculated from the UV absorbance difference of the HSA solution. d, l-tryptophan was selected as the probe solute to characterize the properties of HSA bonded s-triazine chiral stationary phase, and separation factor of 9.4 was obtained for d,l-tryptophan. Furthermore, the amount of effective HSA on silica was measured by high-performance frontal analysis, and only 16.8 mg/g silica was responsible for the resolution of d,l-tryptophan. These results indicate that the amount of both the bound and effective HSA on silica with triazine as activator was much higher than those by the Schiff base coupling method. Different kinds of enantiomers were resolved successfully on the aminopropylsilica-bonded HSA s-triazine chiral stationary phase.

Anti-Inflammatory Agents, Non-Steroidal↗
PubMed2000

Optical resolution of alpha-alkyl phenyl acetonitriles by HPLC on cellulose triacetate chiral stationary phases coated on underivatized silica gel

Microcrystalline celluloses from two sources were used to prepare cellulose triacetate chiral stationary phases (CSPs) coated on underivatized silica gel, which shows discriminating chiral recognition for enantiomers. The chiral separation of four alpha-alkyl phenyl acetonitriles was investigated on the prepared CSPs. It was observed that the concentration of the coating solvent of phenol in dichloromethane plays an important role in the resolution of the solutes. A series of primary alcohols, including secondary and tertiary alcohols, were used as mobile phase modifiers to investigate the effect of the structures of these modifiers on the capacity factors (k') and the separation factors (alpha). Also, the effect of the concentration of alcohol on the capacity factors and separation factors was examined. The chiral recognition mechanism of alpha-alkyl phenyl acetonitriles on the prepared CSPs is discussed. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗
PubMed2000

Longitudinal characterization of synovial fluid biomarkers in the canine meniscectomy model of osteoarthritis.

Damage to the meniscus can lead to posttraumatic osteoarthritis. Early markers of joint injury and tissue disease may be useful in developing and administering clinical treatment. We investigated the effects of total medial meniscectomy on biomarkers measured serially in synovial lavage fluid each month for 3 months. Following meniscectomy in dogs, four biomarkers were evaluated: cartilage oligomeric matrix protein, keratan sulfate epitope (5D4), the 3B3(-) neoepitope of chondroitin-6-sulfate, and the 3B3(+) chondroitinase-generated epitope of chondroitin-6-sulfate. Meniscectomy led to statistically significant elevations of all four biomarkers, with levels peaking at 4 weeks. By 12 weeks, the level of the 5D4 epitope returned to the preoperative baseline level whereas that of cartilage oligomeric matrix protein, 3B3(-), and 3B3(+) remained above the baseline. Concentrations of these biomarkers in the knees not operated on did not change significantly from the baseline. The levels of cartilage oligomeric matrix protein and 3B3(-) relative to 3B3(+) remained constant in all knees. In contrast, the level of 5D4 relative to 3B3(+) declined over time in the knee operated on but remained constant in the knee not operated on. These results demonstrate a quantitative change in the molecular components of synovial fluid after meniscectomy, as well as a qualitative change evinced by an alteration in the relative proportions of these epitopes. Extensive analyses showed a strong correlation between serum levels of 3B3(-) from the femoral and cephalic veins; however, serum 3B3(-) was not correlated with synovial fluid 3B3(-). These findings support the hypothesis that the concentrations of select cartilage biomarkers in synovial fluid are altered following meniscectomy and are promising tools for objectively monitoring the induction of osteoarthritis in this model system.

Animals↗
PubMed2000

Cryopreservation of rhesus macaque (Macaca mulatta) spermatozoa and their functional assessment by in vitro fertilization.

Although spermatozoa from several species of nonhuman primates have been cryopreserved, there has been no report of success with rhesus macaque spermatozoa as judged by functional assays. Two Tris--egg yolk freezing media, TEST and TTE, which have been successfully used for cynomolgus macaque (Macaca fascicularis) spermatozoa, were compared for cryopreservation of spermatozoa from four rhesus macaques (Macaca mulatta). The postthaw motility (percentage and duration) of spermatozoa cryopreserved in TTE was much higher than that for spermatozoa cryopreserved in TEST. The function of sperm cryopreserved in TTE was evaluated by in vitro fertilization of oocytes collected from gonadotropin-stimulated prepubertal rhesus macaques. Of the inseminated oocytes, 82 +/- 13% were fertilized and 63 +/- 22 and 39 +/- 21% of the resulting zygotes developed into morulae and blastocysts, respectively. These results indicate that rhesus macaque spermatozoa can be effectively cryopreserved in TTE medium. This finding will facilitate the application of in vivo and in vitro assisted reproductive technologies in this species.

Animals↗
PubMed2000

Comparison of tyrosine hydroxylase and preproenkephalin expression in rat adrenal medullary explants in vitro and transplanted into subarachnoid space.

When adrenal medullary cells are cultured in vitro, tyrosine hydroxylase (TH) mRNA, preproenkephalin (PPEnk) mRNA, and methionine enkephalin (Mek) immunoreactivity was markedly increased compared with intact adrenal medullary cells in situ, suggesting an increased biosynthesis of catecholamines and enkephalin-containing peptides. In transplanted adrenal medullary cells in vivo, TH mRNA and TH immunoreactivity are still apparent for at least 1 year after transplantation, indicating continued capacity for catecholamine biosynthesis. PPEnk mRNA levels in surviving adrenal medullary grafted cells increased, particularly in the first week after transplantation, and remained above levels found in the intact adrenal gland for at least 1 year after transplantation. These results support other studies in our laboratory, suggesting that adrenal medullary transplants reduce pain by synthesis and secretion of both catecholamines and enkephalin-containing peptides. The differences in expression of TH mRNA and PPEnk mRNA in the adrenal medulla in situ, in explants in culture and in transplants in the spinal subarachnoid space, indicate that the mechanisms regulating the expression of neurohumoral factors depend upon environmental factors extrinsic to the medullary cells themselves.

Adrenal Medulla↗
PubMed2000

Study on tumor angiogenesis in epithelial ovarian carcinoma.

To investigate tumor angiogenesis in benign, borderline and malignant epithelial ovarian tumors and its relation with the pathogenesis of ovarian carcinoma, polycolonal antibody directed against human von Willebrand factor (factor VIII) was used to measure the microvessel density (MVD) in 66 cases (11 benign, 10 borderline, and 45 malignant) of epithelial ovarian tumors by using immunohistochemistry. The results showed that the mean MVD in epithelial ovarian cancer (31.7 +/- 11.2, 400 X) was higher than in benign and borderline tumors (16.7 +/- 6.3, 20.7 +/- 8.8 respectively, P < 0.05). There was no difference in MVDs among those in different tumor grades (P > 0.05). But there was significant difference in MVDs among those in different tumor stages (P < 0.05). MVD in stage III-IV cancer was higher than that in stage I-II (P < 0.05). It is concluded that the tumor angiogenesis is an early event in ovarian tumorgenesis. The increased tumor micovessel might be responsible for tumor development.

Adult↗
PubMed2000

In-vitro antibacterial activities of cefpiramide and other broad-spectrum antibiotics against 440 clinical isolates in China.

The in-vitro antibacterial activity of cefpiramide was compared with those of 15 other broad-spectrum cephalosporins. A total of 440 clinical strains of bacteria, including 9 bacterial species, were isolated from our hospital in 1998. The minimum inhibitory concentrations (MICs) of cefpiramide and five other antibiotics were determined for each species, using the agar-dilution method. The MIC of cefpiramide for Escherichia coli and Klebsiella pneumoniae was higher than those of three other third-generation cephalosporins, (ie, cefoperazone, ceftazidime, and ceftriaxone). Fifty-one percent (26/51) of Enterobacter cloacae isolates were resistant to cefpiramide. Cefoperazone/sulbactam and cefepime had greater activity against E. cloacae (resistance, 3.9% and 19.6%, respectively) than cefpiramide. Cefpiramide was more active against Pseudomonas aeruginosa (resistance rates, 12%) than cefoperazone, ceftazidime, ceftriaxone, aztreonam, and cefepime. Cefpiramide-resistant P. aeruginosa strains were resistant to ceftazidime, but 27% of ceftazidime-resistant strains were susceptible to cefpiramide; 15.3% of cefpiramide-resistant S. maltophilia strains were also susceptible to ceftazidime, but 50% of ceftazidime-resistant strains were still susceptible to cefpiramide. Cefoperazone/sulbactam was the most active agent against Acinetobacter baumannii, showing a resistance rate of 2%. Ampicillin/sulbactam, ceftazidime, and cefpiramide were the second most active agents, and about 50% of the tested strains were susceptible to these three antibiotics. Cefpiramide had an activity comparable to that of all tested beta-lactams against oxacillin-susceptible Staphylococcus aureus (MIC90, 2 microg/ml). Against Streptococcus pneumoniae and Haemophilus influenzae, cefpiramide had good activity, with an MIC90 concentration at which 90% of the strain was inhibited of 1 microg/ml and 0.5 microg/ml, respectively. These results indicated that cefpiramide was more active against glucose non-fermenting bacteria than against Enterobacteriaceae, and was very active against oxacillin-susceptible Staphylo-coccus aureus, S. pneumoniae, and H. influenzae. Thus, cefpiramide may be a good choice of drug for the treatment of patients with infections with glucose non-fermenting bacteria and community acquired infections.

Cefazolin↗
PubMed2000

Application of a modified simplex method to the multivariable optimization of a new FIA system for the determination of osmium.

A methodology based on the coupling of experimental design and a modified simplex method is proposed for the optimization of a new flow injection-kinetic system for the spectrophotometric determination of Os (IV) with m-acetylchlorophosphonazo, which has for the first time been used as chromogenic reagent in the quantitative analysis of this element. An orthogonal array design is utilized to design the experimental protocol, in which six variables are varied simultaneously, and obtain the initial simplex using 25 experiments. A modified simplex method is applied to continuously optimize the data of the orthogonal array design; the search for optimum conditions of 6 variables using the modified simplex method required only 25 experiments. The efficiency and simplicity of the coupling of the experimental design and the modified simplex method are attractive for the development of new analytical methods. The method has been applied to the determination of Os (IV) in a refined ore as well as in a secondary alloy and provided satisfactory results.

Journal Article↗
PubMed2000

Pharmacokinetics and antitumor properties in tumor-bearing mice of an enediol analogue inhibitor of glyoxalase I.

PURPOSE: The enediol analogue S-(N-p-chlorophenyl-N-hydroxycarbamoyl)glutathione (CHG) is a powerful, mechanism-based, competitive inhibitor of the methylglyoxal-detoxifying enzyme glyoxalase I. The [glycyl,glutamyl]diethyl ester prodrug form of this compound (CHG(Et)2) inhibits the growth of different tumor cell lines in vitro, apparently by inducing elevated levels of intracellular methylglyoxal. The purpose of this study was to evaluate the pharmacokinetic properties of CHG(Et)2 in plasma esterase-deficient C57BL/6 (Es-1e) mice after intravenous (i.v.) or intraperitoneal (i.p.) administration of bolus doses of CHG(Et)2. In addition, the in vivo antitumor properties of CHG(Et)2 were evaluated against murine B16 melanoma in these mice, and against androgen-independent human prostate PC3 tumor and human colon HT-29 adenocarcinoma in plasma esterase-deficient nude mice. METHODS: Pharmacokinetics were evaluated after either i.v. or i.p. administration of CHG(Et)2 at the maximally tolerated dose of 120 mg/kg to both tumor-free male and female mice and male and female mice bearing subcutaneous B16 tumors. Tissue concentrations of CHG(Et)2, CHG and the [glycyl]monoethyl ester CHG(Et) were measured as a function of time by reverse-phase C18 high-performance liquid chromatography of deproteinized tissue samples. The efficacy of CHG(Et)2 in tumor-bearing mice was evaluated after i.v. bolus administration of CHG(Et)2 at 80 or 120 mg/kg for 5 days each week for 2 weeks, or after 14 days continuous infusion of CHG(Et)2 using Alzet mini-osmotic pumps. Hydroxypropyl-beta-cyclodextrin was used as a vehicle in the efficacy studies. RESULTS: Intravenous administration of CHG(Et)2 resulted in the rapid appearance of CHG(Et)2 in the plasma of tumor-bearing mice with a peak value of 40-60 microM, followed by a first-order decrease with a half-life of about 10 min. There was a corresponding increase in the concentration of inhibitory CHG in the B16 tumors, with a maximum concentration in the range 30-60 microM occurring at 15 min, followed by a decrease to a plateau value of about 6 microM after 120 min. Neither CHG(Et)2 nor its hydrolysis products were detectable in plasma, after i.p. administration of CHG(Et)2 to tumor-free female mice. From the efficacy studies, dosing schedules were identified that resulted in antitumor effects comparable to those observed with the standard antitumor agents Adriamycin (with B16 tumors), cisplatin (with PC3 tumors), and vincristine (with HT-29 tumors). CONCLUSION: This is the first demonstration that a mechanism-based competitive inhibitor of glyoxalase I effectively inhibits the growth of solid tumors in mice when delivered as the diethyl ester prodrug.

Adenocarcinoma↗