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Biomedical subjects

K Wang

Publications and source records attributed to K Wang.

At least 343 records · Page 19Linked to original sources
PubMed1997

[Hemolysis of Scolopendra toxins].

The hemolysis of toxins from alive Scolopendra subspinipes mutilans, medicinal material of Scolopendra subspimipes mutilans and S. multidens have been compared. The result shows that all the toxins have hemolytic activity. The hemolytic activity of the toxin from the medicinal materials of S. subspinipes mutilans is obviously lower than that from alive ones, and that from fresh medicinal materials are twice as high that from old ones, and that from S. multidens is higher than that from S. subspinipes multilans.

Animals↗
PubMed1997

Clarithromycin in the combination therapy for the eradication of Helicobacter pylori in peptic ulcer disease.

BACKGROUND: Clarithromycin is a new macrolide antibiotic which is known to be highly effective in eradicating Helicobacter pylori (H. pylori). In Chinese, the role of clarithromycin for H. pylori is still unclear. METHODS: Between January 1995 and February 1996, 75 patients with active H. pylori-positive duodenal ulcer were enrolled in this study. Three groups were randomized to have (1) 2 x 150 mg nizatidine twice daily, 2 x 250 mg amoxicillin four times daily, and 2 x 250 mg clarithromycin three times daily for two weeks (niz-amox-clar group, N = 25); or (2) 20 mg omeprazole twice daily plus 2 x 250 mg clarithromycin three times daily for two weeks (ome-clar group, N = 25); or (3) 300 mg bismuth subsalicylate four times daily, and 2 x 250 mg amoxicillin four times daily, 250 mg metronidazole four times daily for two weeks (triple therapy group, N = 25). All the patients received H2 receptor antagonist (150 mg nizatidine or ranitidine, or 400 mg cimetidine, twice daily) for the consecutive six weeks. RESULTS: The eradication rate of H. pylori eight weeks after the entry of study was 80%(20/25) in the niz-amox-clar group, 76%(19/25) in the ome-clar group, 88%(22/25) in the triple therapy group (p < 0.05 among the three groups). The ulcer healing rates eight weeks after the entry of study for the niz-amox-clar, the ome-amox, and the triple therapy groups were 84%(21/25), 80%(20/25), and 80%(20/25), respectively (p < 0.05 among the three groups). The number of patients experiencing adverse effects in the niz-amox-clar group, the ome-clar group, and the triple therapy group were 10(40%), 7(28%), and 4(16%), respectively (p > 0.05 among the three groups). CONCLUSIONS: Both nizatidine/amoxicillin/clarithromycin and omeprazole/clarithromycin regimens can achieve good eradication rates and may provide an effective alternative anti-H. pylori treatment in duodenal ulcer diseases.

Adult↗
PubMed1997

A Java-based multi-institutional medical information retrieval system.

JAMI (Java-based Agglutination of Medical Information) is designed as a framework for integrating heterogeneous information systems used in healthcare related institutions. It is one of the implementations under the W3-EMRS project 1 aimed at using the World Wide Web (Web) to unify different hospital information systems. JAMI inherited several design decisions from the first W3-EMRS implementation described in, including using the Web as the communication infrastructure and HL7 as the communication protocol between the heterogeneous systems and the W3-EMRS systems. In addition, JAMI incorporates the growing Java technologies and has a more flexible and efficient architecture. This paper describes JAMI's architecture and implementation. It also present two instances of JAMI, one for the integration of different hospital information systems and another for the integration of two heterogeneous systems within a single hospital. Some important issues for the further development of JAMI, including security and confidentiality, data input and decision support are discussed.

Computer Communication Networks↗
PubMed1997

[Epidemiological study of external genital diseases in 5172 adolescents].

OBJECTIVE: To study the incidence of external genital diseases and the health status of external genitalia in male adolescents in china. METHODS: 5172 male adolescents aged 7-22 were sampled randomly to examine the diseases and health status of external genitalia. According to the diagnostic criteria in textbook Surgery (3rd edition), all examinations were carried out by urologists. RESULTS: The total incidence of redundant prepuce was 67.79%, phimosis 10.09%, varicocele 19.82%, hydrocele 0.87%, concealed penis 0.68%, cryptorchidism 0.39%. CONCLUSION: The health status of external genitalia in male adolescents is bad. Redundant prepuce and phimosis are common diseases. The examination of external genitalia should be carried out in the physical examination of admission. This study may provide the theoretical evidence for prevention and treatment of male external genital disease as well as the important data for study on andrology.

Adolescent↗
PubMed1997

[Research of system reliability on Model NXS X-ray image medical machine].

In the paper, according to theoretic reliability analysis and experiment research, the System Reliability of NXS X-ray image medical machine is studied by a new computer digital simulation method. The practical method is mainly suggested on its FTA model simulated by algorithm on a computer, then the Reliability Probability, MTBF and Structure Importance on the machine are obtained. The System Reliability results are discussed in detail finally.

Computer Simulation↗
PubMed1996

Control of formation and dissociation of the high-affinity complex between cytochrome c and cytochrome c peroxidase by ionic strength and the low-affinity binding site.

A new ruthenium photoreduction technique was used to measure the formation and dissociation rate constants kf and kd of the high-affinity complex between yeast iso-1-cytochrome c (yCc) and cytochrome c peroxidase compound I (CMPI) over a wide range of ionic strength. These studies utilized Ru-39-Cc, which contains trisbipyridylruthenium attached to the cysteine residue in the H39C, C102T variant of yCc, and has the same reactivity with CMPI as native yCc. kd and kf were measured by photoreducing a small concentration of Ru-39-Cc in the presence of the oxidized yCcIII: CMPI complex, which must dissociate before Ru-39-CcII can bind to CMPI and reduce the radical action. The value of kd for the 1:1 high-affinity complex is very small at low ionic strength, < 5 s-1 but is increased significantly by binding yCc to a second low-affinity site. However, the low-affinity yCc binding site is not active in direct electron transfer to either the radical cation or the oxyferryl heme in CMPI, and is too weak to play a role in the kinetics at ionic strengths above 70 mM. The value of kd increases to 4000 s-1 at 150 mM ionic strength, while kf decreases from > 3 x 10(9) M-1 s-1 at low ionic strength to 1.3 x 10(9) M-1 s-1 at 150 mM ionic strength. These studies indicate that the rate-limiting step in enzyme turnover is product dissociation below 150 mM ionic strength and intracomplex electron transfer to the oxyferryl heme at higher ionic strength. The interaction between yCc and CcP is optimized at physiological ionic strength to provide the largest possible complex formation rate constant kf without allowing product dissociation to be rate-limiting. The effects of surface mutations on the kinetics provided evidence that the high-affinity binding site used for the reaction in solution is similar to the one identified in the yCc:CcP crystal structure.

Binding Sites↗
PubMed1996

An electron-capture dienophile derivatization agent for increasing sensitivity: determination of a vitamin D analog (Ro 24-2090) in plasma samples with liquid chromatography/mass spectrometry.

A practical analytical method has been developed for the determination of an analog of vitamin D3 (Ro 24-2090) in plasma samples. The method employs liquid-liquid extraction, precolumn derivatization, HPLC separation using an automated column-switching system, and particle-beam negative ionization MS determination. An electron-capture derivatization reagent, 4-pentafluorobenzyl-1,2,4-triazoline-3,5-dione, is utilized to attain high sensitivity through a unique ionization mechanism. The method achieved a lower limit of quantitation of 25 pg (63 fmol) of Ro 24-2090 in plasma aliquots ranging from 0.125 to 1.0 ml. Method validation data were obtained for the quantitation of Ro 24-2090 in plasma from humans and seven animal species. Intraassay precision [mean percent relative standard deviation (%RSD)] ranged from 1.49 to 7.12% among the various species. Interassay precision (mean %RSD) ranged from 4.28 to 17.5%. Mean overall recovery ranged from 71 to 89%. The method has been successfully used to analyze plasma samples from several pharmacokinetic studies. The potential use of this method for determination of vitamin D2, vitamin D3, 1 alpha, 25-dihydroxyvitamin D3, and other drugs containing a diene structural moiety is discussed.

Animals↗
PubMed1996

Design of a ruthenium-cytochrome c derivative to measure electron transfer to the radical cation and oxyferryl heme in cytochrome c peroxidase.

A new ruthenium-labeled cytochrome c derivative was designed to measure the actual rate of electron transfer to the Trp-191 radical cation and the oxyferryl heme in cytochrome c peroxidase compound I {CMPI(FeIV = O,R.+)}. The H39C,C102T variant of yeast iso-1-cytochrome c was labeled at the single cysteine residue with a tris (bipyridyl)ruthenium(II) reagent to form Ru-39-Cc. This derivative has the same reactivity with CMPI as native yCc measured by stopped-flow spectroscopy, indicating that the ruthenium group does not interfere with the interaction between the two proteins. Laser excitation of the 1:1 Ru-39-Cc-CMPI complex in low ionic strength buffer (2 mM phosphate, pH 7) resulted in electron transfer from RuII* to heme c FeIII with a rate constant of 5 x 10(5) s-1, followed by electron transfer from heme c Fe II to the Trp-191 indolyl radical cation in CMPI(FeIV = O,R*+) with a rate constant of k(eta) = 2 x 10(6) s-1. A subsequent laser flash led to electron transfer from heme c to the oxyferryl heme in CMPII-(FeIV = O,R) with a rate constant of k(etb) = 5000 s-1. The location of the binding domain was determined using a series of surface charge mutants of CcP. The mutations D34N, E290N, and A193F each decreased the values of k(eta) and k(etb) by 2-4-fold, consistent with the use of the binding domain identified in the crystal structure of the yCc-CcP complex for reduction of both redox centers [Pelletier, H., & Kraut, J. (1992) Science 258, 1748-1755]. A mechanism is proposed for reduction of the oxyferryl heme in which internal electron transfer in CMPII(FeIV = O,R) leads to the regeneration of the radical cation in CMPII-(FeIII,R*+), which is then reduced by yCcII. Thus, both steps in the complete reduction of CMPI involve electron transfer from yCcII to the Trp-191 radical cation using the same binding site and pathway. Comparison of the rate constant k(eta) with theoretical predictions indicate that the electron transfer pathway identified in the crystalline yCc-CcP complex is very efficient. Stopped-flow studies indicate that native yCcII initially reduces the Trp-191 radical cation in CMPI with a second-order rate constant ka, which increases from 1.8 x 10(8) M-1 s-1 at 310 mM ionic strength to > 3 x 10(9) M-1 s-1 at ionic strengths below 100 mM. A second molecule of yCcII then reduces the oxyferryl heme in CMPII with a second-order rate constant kb which increases from 2.7 x 10(7) M-1 s-1 at 310 mM ionic strength to 2.5 x 10(8) M-1 s-1 at 160 mM ionic strength. As the ionic strength is decreased below 100 mM the rate constant for reduction of the oxyferryl heme becomes progressively slower as the reaction is limited by release of the product yCcIII from the yCcIII-CMPII complex. Both ruthenium photoreduction studies and stopped-flow studies demonstrate that the Trp-191 radical cation is the initial site of reduction in CMPI under all conditions of ionic strength.

2,2'-Dipyridyl↗
PubMed1996

BID: a novel BH3 domain-only death agonist.

The BCL-2 family of proteins consists of both antagonists (e.g., BCL-2) and agonists (e.g., BAX) that regulate apoptosis and compete through dimerization. The BH1 and BH2 domains of BCL-2 are required to heterodimerize with BAX and to repress cell death; conversely, the BH3 domain of BAX is required to heterodimerize with BCL-2 and to promote cell death. To extend this pathway, we used interactive cloning to identify Bid, which encodes a novel death agonist that heterodimerizes with either agonists (BAX) or antagonists (BCL-2). BID possesses only the BH3 domain, lacks a carboxy-terminal signal-anchor segment, and is found in both cytosolic and membrane locations. BID counters the protective effect of BCL-2. Moreover, expression of BID, without another death stimulus, induces ICE-like proteases and apoptosis. Mutagenesis revealed that an intact BH3 domain of BID was required to bind the BH1 domain of either BCL-2 or BAX. A BH3 mutant of BID that still heterodimerized with BCL-2 failed to promote apoptosis, dissociating these activities. In contrast, the only BID BH3 mutant that retained death promoting activity interacted with BAX, but not BCL-2. This BH3-only molecule supports BH3 as a death domain and favors a model in which BID represents a death ligand for the membrane-bound receptor BAX.

Amino Acid Chloromethyl Ketones↗
PubMed1996

alpha-crystallin stabilizes actin filaments and prevents cytochalasin-induced depolymerization in a phosphorylation-dependent manner.

alpha-crystallin, a major lens protein of approximately 800 kDa with subunits of about 20 kDa has previously been shown to act as a chaperone protecting other proteins from stress-induced damage and to share sequence similarity with small heat-shock proteins, sHsp. It is now demonstrated that this chaperone effect extends to protection of the intracellular matrix component actin. It was found that the powerful depolymerization effect of cytochalasin D could be almost completely blocked by alpha-crystallin, alpha A-crystallin or alpha B-crystallin. However, phosphorylation of alpha-crystallin markedly decreased its protective effect. It is suggested that phosphorylation of alpha-crystallin may contribute to changes in actin structure observed during cellular remodeling that occurs with the terminal differentiation of a lens epithelial cell to a fiber cell and contributes to cellular remodeling in other cell types that contain alpha-crystallin species. This communication presents biochemical evidence clearly demonstrating that alpha-crystallin is involved in actin polymerization-depolymerization dynamics. It is also shown that alpha-crystallin prevented heat-induced aggregation of actin filaments. alpha-crystallin was found to stabilize actin polymers decreasing dilution-induced depolymerization rates up to twofold while slightly decreasing the critical concentration from 0.23 microM to 0.18 microM. Similar results were found with either alpha-crystallin or its purified subunits alpha A-crystallin and alpha B-crystallin. In contrast to the experiments with cytochalasin D, phosphorylation had no effect. There does not appear to be an interaction between alpha-crystallin and actin monomers since the effect of alpha-crystallin in enhancing actin polymerization does not become apparent until some polymerization has occurred. Examination of the stoichiometry of the alpha-crystallin effect indicates that 2-3 alpha-crystallin monomers/actin monomer give maximum actin polymer stabilization.

Actins↗
PubMed1996

Genomic structure and expression of STM2, the chromosome 1 familial Alzheimer disease gene.

Mutations in the gene STM2 result in autosomal dominant familial Alzheimer disease. To screen for mutations and to identify regulatory elements for this gene, the genomic DNA sequence and intron-exon structure were determined. Twelve exons including 10 coding exons were identified in a genomic region spanning 23,737 bp. The first 2 exons encode the 5'-untranslated region. Expression analysis of STM2 indicates that two transcripts of 2.4 and 2.8 kb are found in skeletal muscle, pancreas, and heart. In addition, a splice variant of the 2.4-kb transcript was identified that is the result of the use of an alternative splice acceptor site located in exon 10. The use of this site results in a transcript lacking a single glutamate. The promotor for this gene and the alternatively spliced exons leading to the 2.8-kb form of the gene remain to be identified. Expression of STM2 was high in skeletal muscle and pancreas, with comparatively low levels observed in brain. This expression pattern is intriguing since in Alzheimer disease, pathology and degeneration are observed only in the central nervous system.

Alternative Splicing↗
PubMed1996

Human skeletal muscle nebulin sequence encodes a blueprint for thin filament architecture. Sequence motifs and affinity profiles of tandem repeats and terminal SH3.

Analysis of deduced protein sequence and structural motifs of approximately 5500 residues of human fetal skeletal muscle nebulin reveals the design principles of this giant multifunctional protein in the sarcomere. The bulk of the sequence is constructed of approximately 150 tandem copies of approximately 35-residue modules that can be classified into seven types. The majority of these modules form 20 super-repeats, with each super-repeat containing a 7-module set (one of each type in the same order). These super-repeats are further divided into eight segments: with six segments containing adjacent, highly homologous super-repeats, one single repeat segment consisting of 8 nebulin modules of the same type, and a non-repeat segment terminating with a SH3 domain at the C terminus. The interactions of actin, tropomyosin, troponin, and calmodulin with nebulin fragments consisting of either repeating modules or the SH3 domain support its role as a giant actin-binding cofilament of the composite thin filament. Such affinity profiles also suggest that nebulin may bind to tropomyosin and troponin to form a composite calcium-linked regulatory complex on the thin filament. The modular construction, super-repeat structure, and segmental organization of nebulin sequence appear to encode thin filament length, periodicity, insertion, and sarcomere proportion in the resting muscle.

Actin Cytoskeleton↗