21 research outputs found

    Importance of the difference in surface pressures of the cell membrane in doxorubicin resistant cells that do not express Pgp and ABCG2

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    P-glycoprotein (Pgp) represents the archetypal mechanism of drug resistance. But Pgp alone cannot expel drugs. A small but growing body of works has demonstrated that the membrane biophysical properties are central to Pgp-mediated drug resistance. For example, a change in the membrane surface pressure is expected to support drug–Pgp interaction. An interesting aspect from these models is that under specific conditions, the membrane is predicted to take over Pgp concerning the mechanism of drug resistance especially when the surface pressure is high enough, at which point drugs remain physically blocked at the membrane level. However it remains to be determined experimentally whether the membrane itself could, on its own, affect drug entry into cells that have been selected by a low concentration of drug and that do not express transporters. We demonstrate here that in the case of the drug doxorubicin, alteration of the surface pressure of membrane leaflets drive drug resistance

    Establishment and characterization of a bladder cancer cell line with enhanced doxorubicin resistance by mevalonate pathway activation

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    Resistance to chemotherapy is a major problem in the treatment of urothelial bladder cancer. Several mechanisms have been identified in resistance to doxorubicin by analysis of resistant urothelial carcinoma (UC) cell lines, prominently activation of drug efflux pumps and diminished apoptosis. We have derived a new doxorubicin-resistant cell line from BFTC-905 UC cells, designated BFTC-905DOXO-II. A doxorubicin-responsive green fluorescent protein (GFP) reporter assay indicated that resistance in BFTC905-DOXO-II was not due to increased drug efflux pump activity, whereas caspase-3/7 activation was indeed diminished. Gene expression microarray analysis revealed changes in proapoptotic and antiapoptotic genes, but additionally induction of the mevalonate (cholesterol) biosynthetic pathway. Treatmentwithsimvastatin restored sensitivity of BFTC-905DOXO-II to doxorubicin to that of the parental cell line. Induction of the mevalonate pathway has been reported as a mechanism of chemoresistance in other cancers; this is the first observation in bladder cancer. Combinations of statins with doxorubicin-containing chemotherapy regimens may provide a therapeutic advantage in such case

    Human Herpesvirus 8 as a Potential Sexually Transmitted Agent in Honduras

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    The seroprevalence of human herpesvirus 8 (HHV-8) was studied in 326 human immunodeficiency virus (HIV)–positive and –negative persons from Honduras; women constituted 77% (n = 251) of the subjects. Sera were tested for lytic HHV-8 antibodies by an IFA, and positive samples were confirmed by a radioimmunoprecipitation assay. Of the 326 persons tested, 58 (17.8%) had HHV- 8 antibodies. Among the HIV-infected women, 22.7% were seropositive; 11.3% of the HIV-negative women were seropositive. HHV-8 seroprevalence was almost four times higher in HIV-positive female commercial sex workers (36%) than in HIV-negative female non–commercial sex workers (9.9%; odds ratio = 3.8, 95% confidence interval = 1.1–13; P = 0.01), suggesting that commercial sex work is a risk factor for HHV-8 infection. In the men studied, the overall HHV-8 seroprevalence was 22.6%, with a seropositivity rate of 28% for HIV-positive men compared with 12% for HIVnegative men

    Modernization and assessment of technical condition of precast concrete buildings (part 2)

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    W pierwszej części artykułu przedstawiono metody oceny stanu technicznego budynków w aspekcie wymagań bezpieczeństwa konstrukcji oraz właściwości akustycznych, izolacyjnych i higieniczno-zdrowotnych. Z uwagi na różnorodność istniejących budynków mieszkalnych, a także wysokie oczekiwania użytkowników zaprezentowano możliwości modernizacyjne budynków wielkopłytowych, również w zakresie ingerencji w ustroje konstrukcyjne. Druga część zawiera informacje o sposobach modernizacji budownictwa wielkopłytowego na konkretnych przykładach.The first part of the following paper presents methods of assessing technical conditions of buildings in terms of the requirements concerning construction safety, acoustical performance, the requirements regarding insulation properties as well as health and safety issues. Due to the variety of residential buildings and high expectations of their residents, possibilities of modernization of precast concrete buildings have been presented, including those that involve the alternation of lead bearing structures. The second part of this paper presents, on specific examples, methods of precast concrete buildings’ modernizatio

    Diagnostics and modernization of prefabricated concrete buildings (part 1)

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    W referacie przedstawiono wyniki wieloletniej działalności ITB w zakresie budownictwa wielkopłytowego, publikowane [1] w serii: Budynki wielkopłytowe - wymagania podstawowe (zeszyty 1÷12) oraz w artykułach i referatach na konferencjach naukowo-technicznych. Przedstawiono metody oceny stanu technicznego budynków w aspekcie wymagań bezpieczeństwa konstrukcji oraz właściwości akustycznych, izolacyjnych i higieniczno-zdrowotnych. Z uwagi na różnorodność istniejących budynków mieszkalnych, a także wysokie oczekiwania użytkowników zaprezentowano możliwości modernizacyjne budynków wielkopłytowych, również w zakresie ingerencji w ustroje konstrukcyjne. Referat stanowi merytoryczną i multidyscyplinarną polemikę z nieuprawnionymi poglądami o hipotetycznym zagrożeniu bezpieczeństwa budynków wielkopłytowych.This paper describes the results of work carried out by the Building Research Institute (ITB) over many years in relation to prefabricated concrete buildings, published [1] in the series Large Panel Buildings – Basic Requirements (volumes 1–12) and in articles and papers given at scientific and technical conferences. Methods are given for assessing the technical condition of buildings, in terms of structural safety requirements as well as acoustic properties, insulation, and health and hygiene. In view of the variety of types of residential buildings in existence, as well as the high expectations of users, possible ways of modernizing prefabricated concrete buildings are described, including those involving structural alterations. The paper provides substantial, multidisciplinary arguments to counter groundless concerns regarding threats to the safety of buildings of this type
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