Breast cancer resistance protein (BCRP/ ABCG2), an ATP-binding cassette half transporter, confers multidrug resistance (MDR) to a series of antitumor agents such as mitoxantrone, daunorubicin, SN-38, and topotecan, and often limits the efficacy of chemotherapy. Recent studies have indicated that a putative estrogen response element (ERE) is located in the promoter region of the BCRP gene. However, whether and how BCRP is regulated transcriptionally by toremifene (TOR) remains unknown. In the present study, two plasmid vectors have been designed to express the wild-Type full-length BCRP cDNA enforced driven by its endogenous promoter containing a functional ERE and a constitutive cytomegalovirus (CMV) promoter as control, respectively, which were transfected into estrogenresponsive MCF-7 and estrogen-independent MDA-MB-231 human breast adenocarcinoma cell lines. We showed that toremifene alone significantly downregulated BCRP mRNA and protein levels in estrogen receptor a (ERa)-positiveMCF- 7 cells in a dose-dependent manner, and the inhibitory effect was partially reversed by estrone (E1). Furthermore, gel shift assays demonstrated that specific binding of ERa to the ERE in the BCRP promoter is essential for transcriptional inhibition of BCRP by toremifene. Interestingly, toremifene alone increased the cellular accumulation of mitoxantrone inBCRPtransfected cells, suggesting that TOR indeed inhibits BCRPmediated drug efflux and overcome drug resistance. To the best of our knowledge, this is the first report describing a direct effect of toremifene on BCRP. Our results thus indicate that toremifene by itself downregulates BCRP expression to reverse BCRP-mediated atypical multidrug resistance via a novel transcriptionally mechanism, which might be involved inTOR-ERcomplexes binding to theEREofBCRP promoter to repress transcription of BCRP gene.

Natural microbial communities are the ultimate drivers of change in any ecosystem. Through chemical contamination of natural environments, these communities are exposed to many different types of chemical stressors; however, research on whole genome responses to this contaminant stress is limited. This research examined the stress response of a common soil bacterium, <i>Pseudomonas aeruginosa</i>, to a common environmental pollutant, pentachlorophenol (PCP). In the first part of the research, it was revealed that nutrient-limited <i>P. aeruginosa</i> is able to respond to PCP with minimal physiological damage due to the upregulation of multidrug efflux pumps. Further study of this PCP-mediated induction of efflux pumps revealed a simultaneous increase in antibiotic resistance. It was discovered that the resistance nodulation-cell division (RND) efflux pump, MexAB-OprM, in particular is responsible for the PCP-induced increase in antibiotic resistance. Both whole cell physiological indicators and whole genome analysis were used to examine the stress response of <i>P. aeruginosa</i> to PCP. Cells were grown in a chemostat at a low growth rate to simulate nutrient-limiting growth in the natural environment. Whole cell acetate uptake rates (WAUR) and viable cell counts as colony forming units (CFU) were determined as cells were exposed to increasing concentration of PCP. At the same time, changes in gene expression were examined by Affymetrix microarray technology. Results showed little change in whole-cell physiology, with no difference in WAUR and only a slight reduction in CFU. However, the microarrays revealed that over 100 genes either increased or decreased expression greater than two-fold due to the PCP exposure. In particular, multiple multidrug efflux genes were upregulated in response to the PCP. The results were validated by real time reverse transcription polymerase chain reaction (RT-PCR) for one of these genes. Further analysis of the effects of MexAB-OprM showed that this particular efflux pump is essential for the response of <i>P. aeruginosa</i> to the toxin PCP. Induction of multidrug efflux pumps is responsible for the development of antibiotic resistance in strains of <i>P. aeruginosa</i>. Therefore, it was investigated whether PCP might induce resistance to a variety of antibiotics. The research was further extended to examine the effect of a variety of organic contaminants on MexAB-OprM efflux and antibiotic resistance development. PCP, 2,4-dinitrophenol, benzoate and Roundup® all induced antibiotic resistance. However, although MexAB-OprM is required for optimal growth in the presence of all chemicals, this particular efflux pump is only involved in increased resistance with PCP. This was confirmed using RT-PCR as <i>mexB</i> expression was induced by PCP, but not by the other three chemicals. A long term generational study on the effects of PCP did not result in a stable antibiotic-resistant phenotype; however, RT-PCR showed that <i>mexB</i> induction is a direct result of PCP exposure and can be reversed by removal of PCP. Together, these results demonstrate the necessity to understand functional responses to contaminant stress. Discovery of direct induction of multidrug efflux pumps and the resulting increase in antibiotic resistance has significant implications for environmental microbiology and public health. This research suggests that organic contamination may result in antibiotic resistance and that antibiotic resistant strains may have a survival advantage in contaminated environments. / Ph. D.

Tuberculosis (TB) is a leading public health problem across the world. For various reasons, TB and multidrug-resistant tuberculosis (MDR-TB) have increased. Clarification on TB/HIV co-infection and homelessness as risk factors for TB and MDR-TB is required to inform policy interventions to reduce TB-related morbidity, mortality, and healthcare costs. In this quantitative study, data from the Houston Health Department (N = 341) were analyzed to explore the relationship between TB and MDR-TB outcomes and TB/HIV co-infection and type of housing/homelessness. Foreign-born persons are disproportionately affected in the United States. The socio-ecological model provided a theoretical framework for the investigation. Multiple and logistic regression analyses were conducted to investigate the relationships between variables, controlling for age and gender. Results indicate that HIV infected persons were more likely than non-infected persons to contract TB, and homeless persons were more likely than non-homeless persons to contract TB/MDR-TB, suggesting that high TB/HIV co-infection rates increase prevalence of TB and MDR-TB while improvements in housing reduce prevalence of TB and MDR-TB. However, no significant associations between variables were found. The odds ratio, Exp(B) = 0.000, p -?¥ 0.90, 95% Cl [0.000, with no upper bound values] was observed for both independent variables. Regular screening for TB/HIV co-infection among persons with high TB and MDR-TB risk profiles is recommended. Further investigation is required. Inclusion of more covariates could further elucidate more evidence of an association between variables. Study findings may support interventions to reduce TB-related morbidity, leading to positive social change.

Multidrug resistance (MDR) is a major obstacle of current chemotherapy. In this study, we investigated the effects ofpolyamines, acetylated polyamines and APAH, a polyamine deacetylase inhibitor, on LS180 cells and the derived MDR LS180 Ad-50 cells. L.ethal concentrations for 20% of the cells (LC20) for N8 -acetylspermidine (N8 - AcSPD) and SPD were 12.5 and 7 times greater for LS180 Ad-50 cells than for LS180 cells, respectively. However, there was no difference in LC20 levels for N1-AcSPD in LS180 and LS180 Ad-50 cells. Addition of 100 nM APAH to N8-AcSPD increased its LC20 to 17 foldgreater in MDR compared to non:·MDR cells. and resulted in increased cell growth at 5 μM N8-AcSPD. Furthermore, exposure to the LC20 concentrations of N8 -AcSPD for 48 hrs caused no significant change of intracellular Rhodamine (Rh) 123 concentrations. Adding 100 nM APAH to this N8 -AcSPD experiment led to a decrease of intracellular Rh123 concentration of 15-20% in both LS 180 and LS 180 Ad-50 cells. These Rh 123 concentrations further decreased in the presence of higher concentrations of APAH. Pretreatment of the cells with APAH did not affect these results. Kinetic studies suggest that APAH may be a non-competitive transport inhibitor of Rh123 transporter.

京都大学 / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19092号 / エネ博第316号 / 新制||エネ||64(附属図書館) / 32043 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 木下 正弘, 教授 森井 孝, 教授 片平 正人 / 学位規則第4条第1項該当 / Doctor of Energy Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21258号 / 医博第4376号 / 新制||医||1029(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 松村 由美, 教授 伊達 洋至, 教授 中川 一路 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

Multidrug resistance (MDR) in breast cancer treatment is the major cause leading to the failure of chemotherapy. P-glycoprotein (P-gp), the product of the human MDR1 gene, plays a key role in resistance to chemotherapy and confers cross-resistance to many structurally unrelated anticancer drugs. We have previously reported that integrin αvβ6 plays a critical role in breast cancer invasion and metastasis. However, whether and how αvβ6 is associated with P-gp and regulated by potential genetic mechanisms in breast cancer remains unclear. In the present study, we further investigated the reversal effect and underlying mechanisms of MDR in breast cancer. Two small interfering RNA constructs (pSUPER-β6shRNAs) targeting two different regions of the β6 gene have been designed to inhibit αvβ6 expression by transfecting them into adriamycin-resistant MCF-7/ADR cell lines. Suppression of αvβ6 dramatically downregulated the levels of MDR1 gene mRNA and P-gp. In particular, β6shRNA-mediated silencing of αvβ6 gene increased significantly the cellular accumulation of Rhodamine 123 and markedly decreased drug efflux ability, suggesting that β6shRNAs indeed inhibit P-gp mediated drug efflux and effectively overcome drug resistance. In addition, inhibition of integrin αvβ6 suppressed the expression of ERK1/2. Interestingly, our data demonstrate that suppression of integrin αvβ6 caused significant downregulation of Bcl-2, Bcl-xL and upregulation of caspase 3, Bad, accompanied by increasing activity of cytochrome C. A possible connection between αvβ6 and P-gp in drug resistance biology is suggested. Taken together, β6shRNA could efficiently inhibit αvβ6 and MDR1 expression in vitro and these findings may offer specifically useful means to reverse MDR in breast cancer therapy.

Bakgrund: Multiresistenta bakterier är ett globalt växande samhällsproblem och ett utav de största folkhälsoproblemen. Förekomsten av multiresistenta bakterier ökar genom användning av antibiotika, framförallt bred-spektrumantibiotika. Multiresistenta bakterier leder till ökad sjuklighet och dödlighet, längre vårdtider och spridning sker både i samhället samt på sjukhus. MRSA, ESBL, VRE och MDR-TB är de multiresistenta bakterier som litteraturstudien fokuserar på. Syfte: Syftet var att belysa sjuksköterskans erfarenheter av att vårda patienter med multiresistenta bakterier. Metod: En allmän litteraturstudie med kvalitativ metod och induktiv ansats utfördes. Åtta vetenskapliga artiklar granskades och analyserades tills kategorier identifierades. Resultat: Analysen resulterade i att fem kategorier identifierades: sjuksköterskans rädslor, otillräcklig kunskap, sjuksköterskans ansvar, organisatoriska brister och utmaningar med patienter i isolering. Sjuksköterskorna beskrev att det förekom hinder i vårdandet av patienter med multiresistenta bakterier såsom bristande kunskap och ledarskap, rädsla för att smittas och smitta andra, avsaknad av riktlinjer samt isolering av patienter. Konklusion: Sjuksköterskor behöver mer kunskap och goda förutsättningar för att kunna ge patienter med multiresistenta bakterier optimal vård. / Background: Multidrug-resistant bacteria are a globally growing problem in society and one of the largest public health problems. The occurrence of multidrug-resistant bacteria increases through the use of antibiotics, especially broad-spectrum antibiotics. Multidrug-resistant bacteria leads to increased morbidity and mortality as well as longer treatments, and the bacteria are spread in both society and in hospitals. The literature study focuses on the multidrug-resistant bacteria MRSA, ESBL, VRE and MDR-TB. Aim: The aim was to illustrate the nurse''s experiences of caring for patients with multidrug-resistant bacteria. Method: A general literature study with a qualitative method and an inductive approach was carried out. Eight scientific articles were reviewed and analyzed until categories were identified. Results: The analysis resulted in five categories being identified: the nurse''s fears, insufficient knowledge, the nurse''s responsibilities, organizational deficiencies and challenges with patients in isolation. The nurses'' described obstacles in the care of patients with multiresistant bacteria such as lack of knowledge and leadership, fear of being infected and infecting others, lack of guidelines and isolation of patients. Conclusion: Nurses need more knowledge and good conditions to be able to give patients with multidrug-resistant bacteria optimal care.

No description available.