12301
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Wang Y, Rao PN. Effect of gossypol on DNA synthesis and cell cycle progression of mammalian cells in vitro. Cancer Res 1984; 44:35-8. [PMID: 6690046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Gossypol, a yellow phenolic compound extracted from cotton plants that is being used as a male antifertility drug, has been found to have cytotoxic effects. The objective of the present study was to determine the cause of these cytotoxic effects in cultured cells and to ascertain whether cells in certain phases of the cell cycle were more sensitive to the drug than were cells in other phases. HeLa or Chinese hamster ovary cells were exposed to various concentrations of gossypol for varying periods of time, and the effects of the drug on the growth rate, cell cycle traverse, plating efficiency, and macromolecular synthesis were measured. The results of this study indicate that gossypol is a specific inhibitor of DNA synthesis; it has no effect on RNA and protein synthesis at a concentration of 10 micrograms/ml and hence has no effect on the cell cycle traverse of cells from G2 to the beginning of S phase. In the presence of the drug, cells can enter S phase but fail to complete replication. The effects of the drug on growth rate and plating efficiency indicate that there is a threshold concentration at which gossypol becomes effective as a cytotoxic agent. Gossypol did not increase chromosome aberrations in the treated cells. Since gossypol irreversibly blocks cells in S phase, it could be useful as an antitumor drug.
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12302
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Wang Y, Cooperman H, Rao V, Koenig S, Brown R. Nuclear magnetic relaxation dispersion profile changes of human tissues. Magn Reson Imaging 1984. [DOI: 10.1016/0730-725x(84)90042-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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12303
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Wang Y. [Choledochoplasty using autogenous graft: an experimental study and clinical observation]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 1983; 21:733-4. [PMID: 6676029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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12304
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Wang Y, Kristensen F, Joncourt F, Slauson DO, De Weck AL. Analysis of 3H-histamine interaction with lymphocytes: receptor binding or uptake? Clin Exp Immunol 1983; 54:501-8. [PMID: 6652970 PMCID: PMC1535901] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The immunoregulatory role of histamine is presumably mediated by specific receptors on the plasma membrane of lymphocytes. However, using murine spleen cells and a whole cell assay commonly applied in hormone receptor studies, specific histamine receptors with an affinity higher than that of non-specific binding could not be identified. Nevertheless, approximately 30% of the totally bound histamine was undissociable over a range of added histamine concentrations (9 X 10(-6)-1 X 10(-2) M). Lectin stimulation of spleen cells caused an additional two-fold increase of undissociable histamine. The H1 receptor antagonist, diphenhydramine, blocked histamine uptake, whereas the H2 receptor antagonist, cimetidine, had no effect. Binding experiments carried out at 4 degrees C demonstrated that the amount of undissociable histamine was much reduced. Even at 4 degrees C, evidence for specific membrane associated histamine receptor could not be obtained. It was therefore concluded that lymphocytes take up histamine by an energy-dependent mechanism inhibitable by diphenhydramine but not cimetidine, and that the usual hormone receptor methodology did not allow the identification of specific membrane associated histamine receptors.
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12305
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Wang Y, Stratowa C, Schaefer-Ridder M, Doehmer J, Hofschneider PH. Enhanced production of hepatitis B surface antigen in NIH 3T3 mouse fibroblasts by using extrachromosomally replicating bovine papillomavirus vector. Mol Cell Biol 1983; 3:1032-9. [PMID: 6308420 PMCID: PMC368632 DOI: 10.1128/mcb.3.6.1032-1039.1983] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We have constructed a recombinant pBR322 plasmid composed of a subgenomic transforming fragment of bovine papillomavirus DNA and the hepatitis B surface antigen gene from cloned hepatitis B virus DNA and used it for transfection of NIH 3T3 mouse fibroblasts. The transformed cells retain the plasmids in extrachromosomal form with a copy number of about 50 to 100 per cell. Expression of the hepatitis B surface antigen gene linked to bovine papillomavirus DNA is independent of its orientation relative to the bovine papillomavirus vector. Cell lines continuously secreting high amounts of hepatitis B surface antigen into the medium could be established. The antigen is released into the culture medium as 22-nm particles, having the same physical properties and constituent polypeptides as those found in the serum of hepatitis B virus-infected patients.
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12306
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Wang DB, Zheng KQ, Qiu MS, Liang ZH, Wu RL, Chen CQ, Wang EB, Zhu YS, Shen QX, Yu YH, Wang Y, Chen HB, Yang ZW, Lu YH, Chen S, Wang GH, Hu MH. Total synthesis of yeast alanine transfer ribonucleic acid. SCIENTIA SINICA. SERIES B, CHEMICAL, BIOLOGICAL, AGRICULTURAL, MEDICAL & EARTH SCIENCES 1983; 26:464-81. [PMID: 6553356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
Abstract
By a combination of chemical and enzymatic methods, small oligonucleotides with lengths varying from 2 to 8 nucleotides were synthesized from mononucleotides. The small oligonucleotides were then ligated with T4 RNA ligase into six large oligonucleotides (9 to 19 nucleotides long) which were further ligated to form two half molecules with 35 and 41 nucleotides respectively. Finally, the two synthetic half molecules were annealed and ligated to obtain the whole molecule of yeast alanine tRNA (tRNAAlay). Prior to this, two semi-syntheses were performed, i.e. ligation of the synthetic 5'-half molecule with the natural 3'-half molecule and that of the natural 5'-half molecule with the synthetic 3'-half molecule. Both the semi-synthetic tRNAAlay and the synthetic tRNAAlay occupy the same position as the natural tRNAAlay after electrophoresis on a 20% polyacrylamide gel. They have the same chemical composition (containing 9 modified nucleotides of 7 different species) and structure as the natural tRNAAlay and are biologically active, i.e. accepting and transferring alanine into proteins in a cell-free protein synthesizing system, the accepting activity of the synthetic product is 52-66% of that of the natural tRNAAlay and 91-106% of that of the reconstituted product of the two natural half molecules. The incorporation activity of alanine into proteins of the synthetic 3H-alanine tRNAAlay is 63%, corresponding to 91% of that of the natural tRNAAlay and 115% of that of the reconstituted product of the two natural half molecules. To the best of our knowledge, this is the first time that a natural RNA with biological activity is synthesized.
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12307
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Yao EH, Wang Y. Acute upper gastrointestinal bleeding in the aged. A retrospective analysis of 100 cases. Med J Aust 1983; 1:311-2. [PMID: 6601227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
One hundred consecutive patients (predominantly men, aged 60 years and older), who were admitted to the Hsinhua Hospital, Shanghai, with acute bleeding from the gastrointestinal tract during a three-year period, were reviewed. The most common causes of bleeding were peptic ulcers, chronic gastritis, prolapse of gastric mucosa, and other benign conditions. In 22 patients, bleeding was either due to oesophageal varices, or was a complication of cor pulmonale. The incidence of malignant disease was 23% (higher than that reported from the United States or the United Kingdom). The mortality rate in patients with benign causes of gastrointestinal bleeding (after exclusion of patients with malignant disease, cor pulmonale, and hepatic cirrhosis) was 4.4%--much lower than the British rate, but slightly higher than that reported in an Australian study. It is hoped that, with the increasing interest in geriatrics, and closer attention to acute bleeding from the gastrointestinal tract in the aged, the mortality rate from this condition will decline.
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12308
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Hu WS, Pang XB, Wang Y, Hu CJ, Lü FH. Mode of action of tetrandrine on vascular smooth muscle. J TRADIT CHIN MED 1983; 3:7-12. [PMID: 6553137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/05/2023]
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12309
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Wang Y, Bonder EM, Mooseker MS, Taylor DL. Effects of villin on the polymerization and subunit exchange of actin. CELL MOTILITY 1983; 3:151-65. [PMID: 6883468 DOI: 10.1002/cm.970030205] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
We have investigated the Ca2+ -dependent interactions of villin, a protein of the intestinal microvillar core, with actin by monitoring resonance energy transfer between fluorescently labeled actin subunits. In the presence of elevated free Ca2+ (approximately 20 microM), villin affects both the nucleation and the elongation phases of actin polymerization. Consistent with previous reports, villin stimulates the nucleation process and will form stable nuclei under depolymerization conditions. Compared to the control, the net rate of polymerization is slightly inhibited at low concentrations of villin (villin/actin approximately 1:400) but is stimulated at higher concentrations (villin/actin greater than 1:100). Villin also significantly increases the critical concentration of actin polymerization. Addition of either villin or villin-actin complexes induces depolymerization of preassembled actin filaments. This villin-induced depolymerization is reversible upon removal of free Ca2+ or upon the addition of phalloidin. The exchange of actin subunits at steady state is inhibited at low concentrations of villin (villin/actin approximately 1:200) but is stimulated at higher concentrations (villin/actin approximately 1:50). None of the above effects is observed at less than 10(-8) M free [Ca2+].
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12310
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Joncourt F, Wang Y, Kristensen F, de Weck A. Aging and Immunity: Decrease in Interleukin-2 Production and Interleukin-2-Dependent RNA-Synthesis in Lectin-Stimulated Murine Spleen Cells. Immunobiology 1982. [DOI: 10.1016/s0171-2985(82)80065-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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12311
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Wang Y. [Cytotoxic activity of human macrophage against human malignant cell lines]. ZHONGHUA YI XUE ZA ZHI 1982; 62:712-4. [PMID: 6820317] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12312
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Joncourt F, Wang Y, Kristensen F, de Weck AL. Aging and immunity: decrease in interleukin-2 production and interleukin-2-dependent RNA-synthesis in lectin-stimulated and murine spleen cells. Immunobiology 1982; 163:521-6. [PMID: 6186595] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The RNA-content of G1 cells in lectin-stimulated spleen cell cultures of young and aged NMRI mice was determined by flow cytometry. In spleen cells of aged mice a preferential decrease of G1 cells with a high RNA-content, so-called G1b cells, was found. Since, as shown in a previous report, only cells with a high RNA-content are able to proliferate and the passage of low (G1a) to high (G1b) RNA-content is interleukin-2(IL-2)-dependent, the ability of young and old spleen cells to produce IL-2 was tested. In old spleen cells a diminished production of IL-2 was found. Addition of external IL-2, however, did not increase the proliferative capacity of old spleen cells, nor did it induce more G1b cells. Thus spleens of aged mice contain cells, which can be activated by lectin, but then fail to respond to IL-2. Both decrease in IL-2 production and receptivity for IL-2 may contribute to the diminishing immune response in aging individuals.
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12313
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Wang Y, Schäfer-Ridder M, Stratowa C, Wong TK, Hofschneider PH. Expression of hepatitis B surface antigen in unselected cell culture transfected with recircularized HBV DNA. EMBO J 1982; 1:1213-6. [PMID: 6327256 PMCID: PMC553191 DOI: 10.1002/j.1460-2075.1982.tb00015.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hepatitis B virus (HBV) DNA was isolated from the recombinant plasmid pA01 -HBV and recircularized . Immediately after introduction of this DNA into mouse fibroblasts (NIH 3T3) we observed increasing release of hepatitis B surface antigen (HBsAg) into the culture medium. Later production of HBsAg declined to a lower but constant level. No dominant selective marker and foreign promoter were necessary in this system, which therefore can be used for the study of regulation of HBsAg expression.
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12314
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Wang Y. [Clinical report of 92 cases of acute poisoning by decomposed organofluotic plastics]. ZHONGHUA YI XUE ZA ZHI 1982; 62:358-61. [PMID: 6812926] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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12315
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Abstract
Sixteen consecutive patients (12 with tricuspid atresia) underwent a Fontan procedure, with no operative deaths. There were three late deaths. Eleven of the survivors were electively catheterized 4-25 months postoperatively. Rest and exercise hemodynamics were measured in five patients, and resting hemodynamics alone were measured in three. All exercised patients were New York Heart Association class I Cardiac index was low at rest (2.3 +/- 0.61/min/m2) and during exercise (4.9 +/- 1.11/min/m2) due to a low stroke index both at rest (28 ml) and exercise (35 ml). Accordingly, mixed venous oxygen saturations were decreased (66% at rest and 31% during exercise). These values are significantly lower than those at rest and during exercise from 23 control patients of similar age and size. Heart rates, pulmonary vascular resistances, and left ventricular filling pressures appeared normal both at rest and during exercise. High right atrial pressure at rest (15 mm Hg) was associated with minimal conduit gradient (2 mm Hg). However, exercise increased the mean conduit gradient to 8 mm Hg, demonstrating significant functional conduit obstruction. As expected, the cardiovascular response to exercise is abnormal after the Fontan procedure, even in asymptomatic patients. This abnormal response may be exacerbated by conduit obstruction, and conduit obstruction may not be apparent during resting studies.
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12316
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Schaefer-Ridder M, Wang Y, Hofschneider PH. Liposomes as gene carriers: efficient transformation of mouse L cells by thymidine kinase gene. Science 1982; 215:166-8. [PMID: 7053567 DOI: 10.1126/science.7053567] [Citation(s) in RCA: 136] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Stable transformation of mouse L cells deficient in thymidine kinase was achieved by liposome-mediated transfer of a recombinant plasmid carrying the thymidine kinase gene. Ten percent of the recipient cells expressed thymidine kinase activity. The transformed phenotype (for example, 200 out of 10(6) cells) was stable under selective and nonselective conditions. The liposome technique is compared with other methods currently used for gene transfer.
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12317
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Neumann E, Schaefer-Ridder M, Wang Y, Hofschneider PH. Gene transfer into mouse lyoma cells by electroporation in high electric fields. EMBO J 1982; 1:841-5. [PMID: 6329708 PMCID: PMC553119 DOI: 10.1002/j.1460-2075.1982.tb01257.x] [Citation(s) in RCA: 1398] [Impact Index Per Article: 33.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Electric impulses (8 kV/cm, 5 microseconds) were found to increase greatly the uptake of DNA into cells. When linear or circular plasmid DNA containing the herpes simplex thymidine kinase (TK) gene is added to a suspension of mouse L cells deficient in the TK gene and the cells are then exposed to electric fields, stable transformants are formed that survive in the HAT selection medium. At 20 degrees C after the application of three successive electric impulses followed by 10 min to allow DNA entry there result 95 (+/- 3) transformants per 10(6) cells and per 1.2 micrograms DNA. Compared with biochemical techniques, the electric field method of gene transfer is very simple, easily applicable, and very efficient. Because the mechanism of DNA transport through cell membranes is not known, a simple physical model for the enhanced DNA penetration into cells in high electric fields is proposed. According to this ' electroporation model' the interaction of the external electric field with the lipid dipoles of a pore configuration induces and stabilizes the permeation sites and thus enhances cross membrane transport.
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12318
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Stratowa C, Doehmer J, Wang Y, Hofschneider PH. Recombinant retroviral DNA yielding high expression of hepatitis B surface antigen. EMBO J 1982; 1:1573-8. [PMID: 6327280 PMCID: PMC553253 DOI: 10.1002/j.1460-2075.1982.tb01357.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A genomic fragment of hepatitis B virus encoding the surface antigen (HBsAg) was inserted into the proviral genome of Moloney mouse sarcoma virus (MSV), obtained from the mouse cell line G8 -124. The recombinant DNA was introduced into NIH 3T3 mouse fibroblasts. Cells, morphologically transformed by the oncogene of MSV (v-mosM) were selected, established as cell lines and tested for expression of HBsAg. An expression level of up to 4.5 micrograms/10(7) cells/day was detected.
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12319
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Gobel FL, Nordstrom LA, Nelson RR, Wang Y. The pathophysiology of angina pectoris and the effect of lidoflazine. Circulation 1982; 65:I27-32. [PMID: 7030519] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Angina pectoris results from a deficiency in myocardial oxygen supply. The rate-pressure product is an important predictor of myocardial oxygen requirements in patients with ischemic heart disease and in normal persons. The rate-pressure product at the onset of angina pectoris is reproducible under a variety of circumstances with a suitable protocol. In some patients, coronary artery spasm may reduce myocardial blood flow and contribute to the development of angina pectoris. Lidoflazine is a synthetic drug that appears to be a calcium-entry blocker and results in symptomatic improvement in patients with angina pectoris. Lidoflazine reduces the exercising rate-pressure product by its effect on heart rate and by decreasing systemic vascular resistance. It decreases coronary vascular resistance and antagonizes processes leading to an increase in coronary vasomotor tone.
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12320
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Kemeny N, Yagoda A, Wang Y, Field K, Wrobleski H, Whitmore W. Randomized trial of standard therapy with or without poly I:C in patients with superficial bladder cancer. Cancer 1981; 48:2154-7. [PMID: 7028242 DOI: 10.1002/1097-0142(19811115)48:10<2154::aid-cncr2820481006>3.0.co;2-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
Thirty-two patients with superficial urinary bladder tumors were stratified for four variables and randomized after complete transurethral resection and/or fulguration of tumor to receive standard therapy with or without intravenous Poly I:C. Cystoscopies were performed at three- to four-month intervals for up to 48 months. While there was no statistically significant difference in the tumor recurrence rates in the two groups during the first year, a significant increase (P = 0.003) in survival at four years was observed between the Poly I:C group and the control group. The difficulties in evaluating the efficacy of anti-neoplastic agents in the treatment of superficial bladder tumors are discussed.
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12321
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Nicoloff DM, Emery RW, Arom KV, Northrup WF, Jorgensen CR, Wang Y, Lindsay WG. Clinical and hemodynamic results with the St. Jude Medical cardiac valve prosthesis. A three-year experience. J Thorac Cardiovasc Surg 1981; 82:674-83. [PMID: 7300400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Two hundred thirty-two consecutive patients (October 3, 1977, through December, 31, 1980) underwent aortic (AVR), mitral (MVR), or double (DVR) valve replacement with the St. Jude Medical (SJM) prosthesis. Operative mortality for the entire group was 7.3%. There was 100% follow-up. Warfarin (Coumadin) anticoagulation was recommended for all patients. There were no cases of mechanical failure. The incidence of thromboembolism was 0.6/1,000 patient-months for those with AVR, 3/1,000 patient-months for those with MVR, and 0% for those with DVR. Thrombosis of a prosthesis occurred in two patients with DVR. Clinically significant hemolysis occurred in three patients with paravalvar leaks following MVR. Late postoperative prosthetic infection has not occurred. Postoperative catheterization studies in 33 patients revealed no transvalvular gradient at rest in 21 patients. The remainder of the patients catheterizd had low transvalvular gradients. There was a minimal increase in transvalvular gradient with exercise. The SJM cardiac valve is a viable alternative in the surgical therapy of valvular heart disease.
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12322
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Cao HL, Wang FL, Du XL, Chen SX, Wang Y, Liu CB. [Preliminary studies on HBsAg excretion from saliva in healthy carriers and epidemiological pattern of hepatitis B (author's transl)]. ZHONGGUO YI XUE KE XUE YUAN XUE BAO. ACTA ACADEMIAE MEDICINAE SINICAE 1981; 3:179-82. [PMID: 6459179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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12323
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Peng S, Wang Y, Ho T. Molecular structure of a four-coordinated macrocyclic Ni-complex [Ni(C 26H 14N 8)]. Acta Crystallogr A 1981. [DOI: 10.1107/s0108767381092593] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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12324
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Petrow V, Wang Y, Lack L, Sandberg A. Prostatic cancer. I. 6-Methylene-4-pregnen-3-ones as irreversible inhibitors of rat prostatic delta 4-3 ketosteroid 5 alpha-reductase. Steroids 1981; 38:121-40. [PMID: 7303026 DOI: 10.1016/0039-128x(81)90027-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Some derivatives of 6-methylene-4-pregnen-3-one were studied as inhibitors of delta 4-3-ketosteroid 5 alpha-reductase. Maximum inhibitory activity was shown by 17-acetoxy-6-methylene-4-pregnene-3,20-dione (AMPD). Irreversible inactivation was observed following preincubation of the enzyme with NADPH and AMPD. This inactivation was found to occur only in the presence of NADPH. As such enzyme inactivation was not due to the formation of a more inhibitory metabolic product, or to the formation of superoxide via a cytochrome P-450/NADPH pathway, it seemed likely that the observed inactivation was derived from an irreversible combination of the enzyme with AMPD. That this was probably the case was established by kinetic studies which revealed a pattern compatible with a kcat type of mechanism.
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12325
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Gabe EJ, Wang Y, Le Page Y. 6,6'-Dibromo-2,2',4,4'-tetra-tert-butylazobenzene. ACTA CRYSTALLOGRAPHICA SECTION B: STRUCTURAL SCIENCE 1981. [DOI: 10.1107/s0567740881004846] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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