61 research outputs found
Comparative Hepatic and Intestinal Efflux Transport of Statins
Previous studies have shown that lipid-lowering statins are transported by various ATP-binding cassette (ABC) transporters. However, because of varying methods, it is difficult to compare the transport profiles of statins. Therefore, we investigated the transport of 10 statins or statin metabolites by six ABC transporters using human embryonic kidney cell-derived membrane vesicles. The transporter protein expression levels in the vesicles were quantified with liquid chromatography-tandem mass spectrometry and used to scale the measured clearances to tissue levels. In our study, apically expressed breast cancer resistance protein (BCRP) and P-glycoprotein (P-gp) transported atorvastatin, fluvastatin, pitavastatin, and rosuvastatin. Multidrug resistance-associated protein 3 (MRP3) transported atorvastatin, fluvastatin, pitavastatin, and, to a smaller extent, pravastatin. MRP4 transported fluvastatin and rosuvastatin. The scaled clearances suggest that BCRP contributes to 87%-91% and 84% of the total active efflux of rosuvastatin in the small intestine and the liver, respectively. For atorvastatin, the corresponding values for P-gp-mediated efflux were 43%-79% and 66%, respectively. MRP3, on the other hand, may contribute to 23%-26% and 25%-37% of total active efflux of atorvastatin, fluvastatin, and pitavastatin in jejunal enterocytes and liver hepatocytes, respectively. These data indicate that BCRP may play an important role in limiting the intestinal absorption and facilitating the biliary excretion of rosuvastatin and that P-gp may restrict the intestinal absorption and mediate the biliary excretion of atorvastatin. Moreover, the basolateral MRP3 may enhance the intestinal absorption and sinusoidal hepatic efflux of several statins. Taken together, the data show that statins differ considerably in their efflux transport profiles. SIGNIFICANCE STATEMENT This study characterized and compared the transport of atorvastatin, fluvastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin acid and four atorvastatin metabolites by six ABC transporters (BCRP, MRP2, MRP3, MRP4, MRP8, P-gp). Based on in vitro findings and protein abundance data, the study concludes that BCRP, MRP3, and P-gp have a major impact in the efflux of various statins. Together with in vitro metabolism, uptake transport, and clinical data, our findings are applicable for use in comparative systems pharmacology modeling of statins.Peer reviewe
A laminin 511 matrix is regulated by TAZ and functions as the ligand for the alpha6Bbeta1 integrin to sustain breast cancer stem cells
Understanding how the extracellular matrix impacts the function of cancer stem cells (CSCs) is a significant but poorly understood problem. We report that breast CSCs produce a laminin (LM) 511 matrix that promotes self-renewal and tumor initiation by engaging the alpha6Bbeta1 integrin and activating the Hippo transducer TAZ. Although TAZ is important for the function of breast CSCs, the mechanism is unknown. We observed that TAZ regulates the transcription of the alpha5 subunit of LM511 and the formation of a LM511 matrix. These data establish a positive feedback loop involving TAZ and LM511 that contributes to stemness in breast cancer
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Geographic information retrieval in a mobile environment: evaluating the needs of mobile individuals
This paper describes research that aims to define the information needs of mobile individuals, to implement a mobile information system that can satisfy those needs, and finally to evaluate the performance of that system with end-users. First a review of the emerging discipline of geographic information retrieval (GIR) is presented as background to the more specific issue of mobile information retrieval. Following this, a user needs study is described evaluating the requirements of potential users of a mobile information system; the study finds that there is a strong geographic component to users' information needs. Next, four geographic post-query filters are described which attempt to represent the region of space associated with an individual's query made at some specific spatial location. These filters are spatial proximity (distance in space), temporal proximity (travel time), speed-heading prediction surfaces (likelihood of visiting locations) and visibility (locations that can be seen). Two of these filters — spatial proximity and speed-heading prediction surfaces — are implemented in a mobile information system and subsequently evaluated with users in an outdoor setting. The results of evaluation suggest that retrieved information to which post-query geographic filters have been applied is considered more relevant than unfiltered information, and that users find information sorted by spatial proximity to be more relevant than that sorted by a prediction surface of likely future locations. The paper closes with a discussion of the wider implications of these results for developers of mobile information systems and location-based services
Sporadic Colorectal Cancer Development Shows Rejuvenescence Regarding Epithelial Proliferation and Apoptosis
Background and Aims: Sporadic colorectal cancer (CRC) development is a sequential process showing age-dependency,
uncontrolled epithelial proliferation and decreased apoptosis. During juvenile growth cellular proliferation and apoptosis
are well balanced, which may be perturbed upon aging. Our aim was to correlate proliferative and apoptotic activities in
aging human colonic epithelium and colorectal cancer. We also tested the underlying molecular biology concerning the
proliferation- and apoptosis-regulating gene expression alterations.
Materials and Methods: Colorectal biopsies from healthy children (n1 = 14), healthy adults (n2 = 10), adult adenomas
(n3 = 10) and CRCs (n4 = 10) in adults were tested for Ki-67 immunohistochemistry and TUNEL apoptosis assay. Mitosis- and
apoptosis-related gene expression was also studied in healthy children (n1 = 6), adult (n2 = 41) samples and in CRC (n3 = 34)
in HGU133plus2.0 microarray platform. Measured alterations were confirmed with RT-PCR both on dependent and
independent sample sets (n1=6, n2=6, n3 = 6).
Results: Mitotic index (MI) was significantly higher (p,0.05) in intact juvenile (MI = 0.3360.06) and CRC samples
(MI = 0.4260.10) compared to healthy adult samples (MI = 0.1560.06). In contrast, apoptotic index (AI) was decreased in
children (0.1360.06) and significantly lower in cancer (0.0660.03) compared to healthy adult samples (0.1760.05). Eight
proliferation- (e.g. MKI67, CCNE1) and 11 apoptosis-associated genes (e.g. TNFSF10, IFI6) had altered mRNA expression both
in the course of normal aging and carcinogenesis, mainly inducing proliferation and reducing apoptosis compared to
healthy adults. Eight proliferation-associated genes including CCND1, CDK1, CDK6 and 26 apoptosis-regulating genes (e.g.
SOCS3) were differently expressed between juvenile and cancer groups mostly supporting the pronounced cell growth in
CRC.
Conclusion: Colorectal samples from children and CRC patients can be characterized by similarly increased proliferative and
decreased apoptotic activities compared to healthy colonic samples from adults. Therefore, cell kinetic alterations during
colorectal cancer development show uncontrolled rejuvenescence as opposed to the controlled cell growth in juvenile
colonic epithelium
miR-17–92 cluster: ups and downs in cancer and aging
The miR-17–92 cluster encoding 6 single mature miRNAs was identified a couple of years ago to contain the first oncogenic miRNAs. Now, one of these 6 miRNAs, miR-19 has been identified as the key responsible for this oncogenic activity. This in turn reduces PTEN levels and in consequence activates the AKT/mTOR pathway that is also prominently involved in modulation of organismal life spans. In contrast, miR-19 and other members of the miR-17–92 cluster are found to be commonly downregulated in several human replicative and organismal aging models. Taken together, these findings suggest that miR-19 and the other members of the miR-17–92 cluster might be important regulators on the cross-roads between aging and cancer. Therefore, we here briefly summarize how this cluster is transcriptionally regulated, which target mRNAs have been confirmed so far and how this might be linked to modulation of organismal life-spans
Noteworthy records of aphyllophoroid fungi in Finland (Basidiomycota)
We present new records of noteworthy aphyllophoroid fungi, mainly polypores and corticioids in Finland. The following 19 rare or infrequently collected species are presented with notes on their substrates: Amylocorticium subsulphureum, Antrodiella parasitica, Ceraceomyces sulphurinus, Clavaria atroumbrina, Clavaria rosea, Gloeophyllum carbonarium, Hyphodontia flavipora, Junghuhnia fimbriatella, Lindtneria chordulata, Odonticium septocystidia, Peniophorella guttulifera, Perenniporia tenuis, Postia immitis, Repetobasidium vile, Resinicium pinicola, Sidera vulgaris, Tomentella coerulea, Trechispora laevis and Xylodon pruni. We also list 41 aphyllophoroid fungi as new to some sections of the boreal vegetation zone in Finland
Major wood-decay fungal groups have distinct occurrence patterns on woody substrates
Abstract
Conservation of wood-inhabiting fungi requires sufficient knowledge of their occurrences on woody substrates. We studied and compared two major fungal wood-decay fungi groups (polypores and corticioids) on dead wood. Eight fungal or substrate groups were separated in the analyses. In total, 6,102 dead wood units were surveyed, and 5,682 occurrences of 302 fungal species were recorded. Our analyses included also empty dead wood units, which is rather rare in quantitative ecological studies of dead wood species. In general, the occurrence of fungal species did not exactly follow the availability of dead wood substrates, indicating high importance of substrate quality on species. Furthermore, polypores and corticioids differed from each other in their substrate occurrence patterns. The largest differences were found in diameter classes, corticioids occurring more often on small dead wood units. Our findings emphasize the importance of maintaining the variation in dead wood quality when preserving the diversity of wood-inhabiting fungi
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