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Sheu JH, Sung PJ, Su JH, Wang GH, Duh CY, Shen YC, Chiang MY, Chen IT. Excavatolides U-Z, new briarane diterpenes from the gorgonian briareum excavatum. JOURNAL OF NATURAL PRODUCTS 1999; 62:1415-1420. [PMID: 10543904 DOI: 10.1021/np990302i] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
A recent study of the EtOAc extract of the gorgonian Briareum excavatum afforded six new diterpenes of the briarane skeleton, excavatolides U-Z (1-6). The structures and relative stereochemistry of metabolites 1-6 were assigned on the basis of NMR studies and chemical methods. The structure, including the relative configuration of excavatolide U (1), was further confirmed by a single-crystal X-ray analysis. Some of the excavatolides have displayed significant cytotoxicity toward P-388 and HT-29 tumor cells.
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Wang DK, Hu TQ, Wang GH. [Implantation of catgut plus Laser for treatment of trigeminal neuralgia]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1999; 8:172-3. [PMID: 15048253] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
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53
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Wang GH, Mitsui K, Kotliarova S, Yamashita A, Nagao Y, Tokuhiro S, Iwatsubo T, Kanazawa I, Nukina N. Caspase activation during apoptotic cell death induced by expanded polyglutamine in N2a cells. Neuroreport 1999; 10:2435-8. [PMID: 10574348 DOI: 10.1097/00001756-199908200-00001] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Huntington disease (HD) is an autosomal dominant neurodegenerative disorder. To investigate the mechanism of neurodegeneration induced by mutant huntingtin, we developed a stable neuro2a cell line expressing truncated N-terminal huntingtin (tNhtt) with EGFP using the ecdysone-inducible system. The formation of aggregates and the cell death induced by expression of tNhtt with expanded polyglutamine was repeat length- and dose-dependent. Caspases were activated, and the death substrates of caspases, lamin B and ICAD (an inhibitor of caspase-activated DNase), were cleaved in this cell death process. The cleavage of lamin B was inhibited by caspase inhibitors. These findings suggest that the cell death induced by tNhtt with expanded polyglutamine is mediated by caspases.
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Sung PJ, Su JH, Wang GH, Lin SF, Duh CY, Sheu JH. Excavatolides F-M, new briarane diterpenes from the gorgonian Briareum excavatum. JOURNAL OF NATURAL PRODUCTS 1999; 62:457-463. [PMID: 10096858 DOI: 10.1021/np980446h] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Eight new briarane-type diterpenes, excavatolides F-M (1-8), have been isolated from the gorgonian Briareum excavatum. The structures and relative stereochemistry of these compounds were established by spectral analysis and chemical methods. The cytotoxicity of these compounds toward various cancer cell lines has also been determined.
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Sheu JH, Wang GH, Sung PJ, Duh CY. New cytotoxic oxygenated fucosterols from the brown alga Turbinaria conoides. JOURNAL OF NATURAL PRODUCTS 1999; 62:224-7. [PMID: 10075746 DOI: 10.1021/np980233s] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Fucosterol (1), 24xi-hydroperoxy-24-vinylcholesterol (2), 29-hydroperoxystigmasta-5,24(28)-dien-3beta-ol (3), 24-ethylcholesta-4,24(28)-dien-3-one (4), 24xi-hydroperoxy-24-ethylcholesta-4,28(29)-dien-3-one (5), 24-ethylcholesta-4,24(28)-dien-3,6-dione (6), 24xi-hydroperoxy-24-ethylcholesta-4,28(29)-dien-3,6-di one (7), 6beta-hydroxy-24-ethylcholesta-4,24(28)-dien-3-one (8), and 24xi-hydroperoxy-6beta-hydroxy-24-ethylcholesta-4,28(2 9)-dien-3-one (9) were isolated from the marine brown alga Turbinaria conoides. The structures of these compounds were established by spectral analysis. Isolated for the first time from a natural source, the oxygenated fucosterols 4-9 exhibit cytotoxicity against various cancer cell lines.
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Niu SR, Yang GH, Chen ZM, Wang JL, Wang GH, He XZ, Schoepff H, Boreham J, Pan HC, Peto R. Emerging tobacco hazards in China: 2. Early mortality results from a prospective study. BMJ (CLINICAL RESEARCH ED.) 1998; 317:1423-4. [PMID: 9822394 PMCID: PMC28720 DOI: 10.1136/bmj.317.7170.1423] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To monitor the evolving epidemic of mortality from tobacco in China following the large increase in male cigarette use in recent decades. DESIGN Prospective study of smoking and mortality starting with 224 500 interviewees who should eventually be followed for some decades. SETTING 45 nationally representative small urban or rural areas distributed across China. SUBJECTS Male population aged 40 or over in 1991, of whom about 80% were interviewed about smoking, drinking, and medical history. MAIN OUTCOME MEASURE Cause specific mortality, initially to 1995 but later to continue, with smoker versus non-smoker risk ratios standardised for area, age, and use of alcohol. RESULTS 74% were smokers (73% current, only 1% former), but few of this generation would have smoked substantial numbers of cigarettes since early adult life. Overall mortality is increased among smokers (risk ratio 1.19; 95% confidence interval 1.13 to 1.25, P<0.0001). Almost all the increased mortality involved neoplastic, respiratory, or vascular disease. The overall risk ratios currently associated with smoking are less extreme in rural areas (1.26, 1.12, or 1.02 respectively for smokers who started before age 20, at 20-24, or at older ages) than in urban areas (1.73, 1.40, or 1.16 respectively). CONCLUSION This prospective study and the accompanying retrospective study show that by 1990 smoking was already causing about 12% of Chinese male mortality in middle age. This proportion is predicted to rise to about 33% by 2030. Long term continuation of the prospective study (with periodic resurveys) can monitor the evolution of this epidemic.
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Wang GH, Wang JQ, Tu ZJ. [Treatment of vertically fractured molars using brackets]. SHANGHAI KOU QIANG YI XUE = SHANGHAI JOURNAL OF STOMATOLOGY 1998; 7:177-8. [PMID: 15071662] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Subscribe] [Scholar Register] [Indexed: 04/29/2023]
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Sheu JH, Wang GH, Sung PJ, Chiu YH, Duh CY. Cytotoxic sterols from the formosan brown alga Turbinaria ornata. PLANTA MEDICA 1997; 63:571-2. [PMID: 17252381 DOI: 10.1055/s-2006-957772] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Two hydroperoxysterols 24-hydroperoxy-24-vinyl-cholesterol (1) and 29-hydroperoxystigmasta-5,24(28)-dien-3beta-ol (2), and fucosterol (3) were isolated from the brown alga Turbinaria ornata (Sargassaceae). Hydroperoxide 2 is a new natural compound and was converted into 29-hydroxystigmasta-5,24 (28)-dien-3beta-ol (4) by reaction with LAH. Sterols 1, 2, and 4 exhibited cytotoxicity against various cancer cell lines.
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Wang GH, Bertin J, Wang Y, Martin DA, Wang J, Tomaselli KJ, Armstrong RC, Cohen JI. Bovine herpesvirus 4 BORFE2 protein inhibits Fas- and tumor necrosis factor receptor 1-induced apoptosis and contains death effector domains shared with other gamma-2 herpesviruses. J Virol 1997; 71:8928-32. [PMID: 9343261 PMCID: PMC192367 DOI: 10.1128/jvi.71.11.8928-8932.1997] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Fas- and tumor necrosis factor receptor 1 (TNFR1)-induced apoptosis is mediated by the interaction of FADD with caspase-8. Here, we report that the bovine herpesvirus 4 (BHV4) BORFE2 gene encodes a protein that inhibits Fas- and TNFR1-induced apoptosis and contains death effector domains (DEDs). Using the yeast two-hybrid system, we found that the BORFE2 protein interacts with the prodomain of caspase-8. Furthermore, we show that BHV4 BORFE2 is a member of a family of DED-containing proteins that includes other gamma-2 herpesviruses, such as Kaposi's sarcoma-associated herpesvirus and herpesvirus saimiri.
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Sheu JH, Huang SY, Wang GH, Duh CY. Study on cytotoxic oxygenated desmosterols isolated from the red alga Galaxaura marginata. JOURNAL OF NATURAL PRODUCTS 1997; 60:900-903. [PMID: 9322362 DOI: 10.1021/np9701844] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Four novel oxygenated desmosterols, 24 zeta-hydroperoxy-6 beta-hydroxycholesta-4,25-dien-3-one (1), 25-hydroperoxy-6 beta-hydroxycholesta-4,23(E)-dien-3-one (2), 24 zeta-hydroperoxycholesta-4,25-diene-3,6-dione (3), and 25-hydroperoxycholesta-4,23(E)-diene-3,6-dione (4) were isolated from the marine red alga Galaxaura marginata. Steroids 1-4 and three synthetic oxygenated desmosterols 5-7 were shown to exhibit significant cytotoxicity against several cancer cell lines.
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61
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Fan LF, Huang YR, Wang GH. [Study on quality of sleep and mental health in patients with hyperthyroidism]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1997; 32:435-9. [PMID: 9495958] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Sleep quality and psychical health were investigated with Pittsburgh Sleeping Quality Index (PSQI) and SCL-90 in 128 patients with hyperthyroidism. The results showed that: 1. The PSQI scores of the patients with ages over 35 years old were higher than that less than 35 years old (P < 0.05). 2. Sleep problems occurred in 87.55% of the patients. Sleep quality of 9.38% of patients were worse. The sleep quality of the female patients were better than the male (P < 0.05). 3. Apart from interpersonal sensitivity, paranoid ideation and psychoticism, scores of the rest were higher than the general people (P < 0.05). 10.2% of the patients with hyperthyroidism had psychical problems. 4. Apart from sleep time and using sleep pill, there was a high correlation between the scores of SCL-90 and PSQI (P < 0.05-P < 0.001). The results showed that sleep problems of the patients with hyperthyroidism affected their psychical health. Lower sleep quality was a main dangerous factor which affected psychical health of the patients with hyperthyroidism.
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Ladner SK, Otto MJ, Barker CS, Zaifert K, Wang GH, Guo JT, Seeger C, King RW. Inducible expression of human hepatitis B virus (HBV) in stably transfected hepatoblastoma cells: a novel system for screening potential inhibitors of HBV replication. Antimicrob Agents Chemother 1997; 41:1715-20. [PMID: 9257747 PMCID: PMC163991 DOI: 10.1128/aac.41.8.1715] [Citation(s) in RCA: 475] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We report the development and isolation of a cell line, termed HepAD38, that replicates human hepatitis B virus (HBV) under conditions that can be regulated with tetracycline. In the presence of the antibiotic, this cell line is free of virus due to the repression of pregenomic (pg) RNA synthesis. Upon removal of tetracycline from the culture medium, the cells express viral pg RNA, accumulate subviral particles in the cytoplasm that contain DNA intermediates characteristic of viral replication, and secrete virus-like particles into the supernatant. Since the HepAD38 cell line can produce high levels of HBV DNA, it should be useful for analyses of the viral replication cycle that depend upon viral DNA synthesis in a synchronized fashion. In addition, this cell line has been formatted into a high-throughput, cell-based assay that permits the large-scale screening of diverse compound libraries for new classes of inhibitors of HBV replication.
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63
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Li XD, Chen WF, Liu WY, Wang GH. Large-scale preparation of two new ribosome-inactivating proteins--cinnamomin and camphorin from the seeds of Cinnamomum camphora. Protein Expr Purif 1997; 10:27-31. [PMID: 9179286 DOI: 10.1006/prep.1996.0706] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
An improved method for large-scale preparation of cinnamomin and camphorin from the seeds of Cinnamomum camphora has been developed. Cinnamomin is a type II ribosome-inactivating protein (RIP), while camphorin is a type I RIP. Cinnamomin was purified by a single step of acid-treated Sepharose 4B affinity chromatography instead of gel filtration. Camphorin was purified by anion-exchange chromatography and gel filtration successively from the eluant not retained by the affinity column. Using this improved method, 620 mg of cinnamomin and 14.2 mg of camphorin were obtained from 500 g of wet seed, while only 10.6 mg of cinnamomin and 4.7 mg of camphorin were obtained by the previous method. Cinnamomin and camphorin purified by this method were homogeneous in SDS-denatured polyacrylamide gel electrophoresis. These two RIPs are multifunctional proteins. The assay of the enzymatic activities of cinnamomin and camphorin showed that both of them exhibit RNA N-glycosidase and supercoil-dependent endonuclease activities, while camphorin also exhibits superoxide dismutase activity.
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Wang GH, Cao SW, Chen BH. [Relieving effect of sodium thiosulfate on transarterial chemotherapeutic emesis]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1997; 32:251-3. [PMID: 9304980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
It was reported that sodium thiosulfate (STS) was contributed to antivomiting effect in 20 transarterial chemotherapic patients. The antitumor sensitivity of STS (< 500 micrograms/ml) adjuncting to the ADM, MMC, CDDP and other four agens (1 x PPC/ml) individually on two tumor cells studied by MTT test in vitro and no antitumor activity of adjuvant of STS were obviously obliterated (P > 0.05) except for CDDP clinically, to comparing the adjuncting effects of STS (iv. 30 min ahead) or metochlopramidum (im. 30 min ahead) to ADM, MMC and CDDP on HCC (40 cases), the degrees of vomiting in hepatoma patient after transcatheter arterial chemoem bolization with ADM, MMC and CDDP were statisticaly analysec. It have been proven that STS was contributed to the low incidence of vomiting and superior to metocloe pramidum, without worsening of the chemotherapy of HCC. It is worth futher studying adjuvant STS to other antitumor drugs and exploring potential application of chematherapy in cancer.
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65
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Wang GH. [Study on teaching reform in internal medicine nursing]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1997; 32:157-9. [PMID: 9304978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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66
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Bertin J, Armstrong RC, Ottilie S, Martin DA, Wang Y, Banks S, Wang GH, Senkevich TG, Alnemri ES, Moss B, Lenardo MJ, Tomaselli KJ, Cohen JI. Death effector domain-containing herpesvirus and poxvirus proteins inhibit both Fas- and TNFR1-induced apoptosis. Proc Natl Acad Sci U S A 1997; 94:1172-6. [PMID: 9037025 PMCID: PMC19763 DOI: 10.1073/pnas.94.4.1172] [Citation(s) in RCA: 355] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To identify novel antiapoptotic proteins encoded by DNA viruses, we searched viral genomes for proteins that might interfere with Fas and TNFR1 apoptotic signaling pathways. We report here that equine herpesvirus type 2 E8 protein and molluscum contagiosum virus MC159 protein both show sequence similarity to the death effector domains (DEDs) of the Fas/TNFR1 signaling components FADD and caspase-8. Yeast two-hybrid analysis revealed that E8 protein interacted with the caspase-8 prodomain whereas MC159 protein interacted with FADD. Furthermore, expression of either E8 protein or MC159 protein protected cells from Fas- and TNFR1-induced apoptosis indicating that certain herpesviruses and poxviruses use DED-mediated interactions to interfere with apoptotic signaling pathways. These findings identify a novel control point exploited by viruses to regulate Fas- and TNFR1-mediated apoptosis.
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Sun Q, Gong XG, Zheng QQ, Sun DY, Wang GH. Local magnetic properties and electronic structures of 3d and 4d impurities in Cu clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1996; 54:10896-10904. [PMID: 9984888 DOI: 10.1103/physrevb.54.10896] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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68
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Fan LF, Li HY, Wang GH. [Study on prevention of untoward reaction of glucose tolerance test]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1996; 31:125-127. [PMID: 8826187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The prevention methods of the side effects of 75g glucose tolerance test were studied. The results showed that the speed of taking glucose water was 3-5 minutes; the water temperature was 20-30 degrees C; water volume of dissolving glucose was 300ml; 0.25g citric acid was added, the side effects will be avoided or reduced.
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69
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Wang GH. [Analysis of the society and psychology of blood dialysis patients]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1995; 30:288-9. [PMID: 8631072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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70
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Wang GH, Chen M, Zhang XQ. [An experimental investigation on preventive measures of skin ulcers induced by extravascular mitomycin C]. ZHONGHUA HU LI ZA ZHI = CHINESE JOURNAL OF NURSING 1995; 30:67-70. [PMID: 7664374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In order to make an investigation on skin ulcer induced by Mitomycin C extravasation, the preventive measures were undergone by the following ex-periment. A subcutaneous ulcerative model induced by 0.1mg Mitomycin C (MMC) extravasation in the leg of BALA/C mice was established. On the model subject, 8 pharmacologic adjuvants or physical modulation were adopted. It is preferential to choose local injection with 0.1 ml 99% dimethyl sulfoxide (DMSO), or with additional smearing DMSO on the affected skin. 10 days later, the ulcerative areas with DMSO treatment were significantly decreased in contrast with 0.1 ml 0.9% NaCI treatment (P < 0.001). The other preferential treatment were in turn by the injection of 0.1 ml 5% NaHCO3 (P < 0.001); 0.1 ml 1% procainamidi hydrochloridum (including 0.4% dexame-thasonum) (P < 0.001) or smearing with 0.1 ml 90% DMSO (including 10% Vit E) (P < 0.01). Delayed application of DMSO after MMC extravasation 30 min had been proven the limited effects on the prevention of ulcer (P < 0.05). Neither cooling of skin or local injection of sodium thiosulfate reduced MMC ulceration (P > 0.05). The mechanisms of prevention of MMC extravascular ulcer by DMSO or 5% NaHCO3 were briefly discussed.
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Wang GH, Jiang XF, Luo WC. [Report of 2 cases of extrinsic allergic alveolitis and review of relevant literature]. ZHONGHUA JIE HE HE HU XI ZA ZHI = ZHONGHUA JIEHE HE HUXI ZAZHI = CHINESE JOURNAL OF TUBERCULOSIS AND RESPIRATORY DISEASES 1994; 17:367-8, 384. [PMID: 7712583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Two cases of extrinsic allergic alveolitis were reported. The antigens inducing the immunologic events are wheat powder, hair-dye liquid. The pathology, symptoms and chest radiograph features were presented. The best treatment is avoidance of antigen exposure and to use of corticosteroids. The chronic form of the disease often leads to irreversible pulmonary interstitial fibrosis.
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Wang GH, Zoulim F, Leber EH, Kitson J, Seeger C. Role of RNA in enzymatic activity of the reverse transcriptase of hepatitis B viruses. J Virol 1994; 68:8437-42. [PMID: 7525990 PMCID: PMC237319 DOI: 10.1128/jvi.68.12.8437-8442.1994] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The hepadnavirus reverse transcriptase is a multifunction enzyme. In addition to its role in DNA synthesis, the polymerase is required for RNA packaging and also functions as the primer for minus-strand DNA synthesis. Previously, we demonstrated that the protein-priming activity of the polymerase requires a viral RNA segment, termed epsilon, which serves as a template for the synthesis of a short DNA oligomer that is covalently attached to the reverse transcriptase (G.-H. Wang and C. Seeger, J. Virol. 67:6507-6512, 1993). We now report that epsilon is sufficient for activation of the reverse transcriptase to prime DNA synthesis through the formation of a stable RNA-protein (RNP) complex. We also demonstrate that the binding reaction depends on sequence-specific determinants on epsilon. Moreover, our results indicate that two genetically separated domains of the reverse transcriptase are required for formation of the RNP complex. Finally, we show that the polymerase has a DNA polymerase activity in the absence of epsilon which does not depend on the protein-priming mechanism.
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Chen L, Kaloyeros AE, Wang GH. Chaotic behavior of channeling particles. CHAOS (WOODBURY, N.Y.) 1994; 4:85-88. [PMID: 12780089 DOI: 10.1063/1.166060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Channeling describes the collimated motion of energetic charged particles along the lattice plane or axis in a crystal. The energetic particles are steered through the channels formed by strings of atomic constituents in the lattice. In the case of planar channeling, the motion of a charged particle between the atomic planes can be periodic or quasiperiodic, such as a simple oscillatory motion in the transverse direction. In practice, however, the periodic motion of the channeling particles can be accompanied by an irregular, chaotic behavior. In this paper, the Moliere potential, which is considered as a good analytical approximation for the interaction of channeling particles with the rows of atoms in the lattice, is used to simulate the channeling behavior of positively charged particles in a tungsten (100) crystal plane. By appropriate selection of channeling parameters, such as the projectile energy E(0) and incident angle psi(0), the transition of channeling particles from regular to chaotic motion is demonstrated. It is argued that the fine structures that appear in the angular scan channeling experiments are due to the particles' chaotic motion.
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Zhao JJ, Han M, Wang GH. Ionization potentials of transition-metal clusters. PHYSICAL REVIEW. B, CONDENSED MATTER 1993; 48:15297-15300. [PMID: 10008066 DOI: 10.1103/physrevb.48.15297] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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Abstract
Reverse transcription of all retroviruses and most retroid elements requires tRNA as a primer for DNA synthesis. However, in hepatitis B viruses the viral polymerase itself acts as a primer for reverse transcription (G.-H. Wang and C. Seeger, Cell 71:663-670, 1992). We have now demonstrated that in order to prime DNA synthesis, the polymerase binds to an RNA hairpin, which then serves as a template for the formation of a short DNA primer that is covalently linked to protein. Following its synthesis, the nascent DNA strand apparently dissociates from its template and reanneals with complementary sequences at the 3' end of the RNA genome, where DNA synthesis continues. Since this RNA hairpin also functions as a packaging signal for viral RNA, hepadnaviruses have adopted a replication strategy that relies on the same signal for two biochemically distinct events, RNA packaging and reverse transcription. This mechanism is without precedent among all known retroid elements and among other viruses and bacteriophages that use protein as a primer for RNA or DNA synthesis. It could provide an effective target for antiviral therapy, which is required for the treatment of more than 300 million carriers of hepatitis B virus.
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