Microarray hybridization analysis was conducted to identify genes that may affect biofilm formation.
Biofilm-forming ability of Staphylococcus aureus strains isolated from human skin.
Specimen part
View SamplesObjective. To identify novel monosodium urate (MSU) crystal-induced mRNAs by transcript profiling of isolated murine air pouch membranes.
No associated publication
No sample metadata fields
View SamplesMdr1a-, Bcrp-, and Mrp2-knockout rats are a more practical species for ADME studies than murine models and previously demonstrated expected alterations in pharmacokinetics of various probe substrates. At present, gene expression and pathology changes were systematically studied in small intestine, liver, kidney, and brain tissue from male SAGE Mdr1a-, Bcrp-, and Mrp2-knockout rats versus wild-type Sprague Dawley controls. Gene expression data supported the relevant knockout genotype. As expected, Mrp2-knockout rats were hyperbilirubinemic and exhibited upregulation of hepatic Mrp3. Overall, few alterations were observed within 137 ADME-relevant genes. The two most consequential changes were upregulation of intestinal carboxylesterase in Mdr1a-knockouts and catechol-O-methyltransferase in all tissues of Bcrp-knockout rats. Previously reported upregulation of hepatic Mdr1b P-glycoprotein in proprietary Wistar Mdr1a-knockout rats was not observed in the SAGE counterpart investigated herein. Relative liver and kidney weights were 22-53% higher in all three knockouts, with microscopic increases in hepatocyte size in Mdr1a- and Mrp2-knockout rats, and glomerular size in Bcrp- and Mrp2-knockouts. Increased relative weight of clearing organs is quantitatively consistent with reported increases in clearance of drugs that are not substrates of the knocked-out transporter. Overall, SAGE knockout rats demonstrated modest compensatory changes, which do not preclude their general application to study transporter-mediated pharmacokinetics. However until future studies elucidate the magnitude of functional change, caution is warranted in rare instances of extensive metabolism by catechol-O-methyltransferase in Bcrp-knockouts and intestinal carboxylesterase in Mdr1a-knockout rats, specifically for molecules with free catechol groups and esters subject to gut wall hydrolysis.
Minor compensatory changes in SAGE Mdr1a (P-gp), Bcrp, and Mrp2 knockout rats do not detract from their utility in the study of transporter-mediated pharmacokinetics.
Sex, Specimen part
View Samples27 sample pairs were conducted exon microarrays and 25 sample pairs were retain for our further alternative splicing analysis. 260 genes showed differential expression in more than 50% of our samples and 21 genes among them were validated by real-time PCR. Six genes with splicing events, which were firstly found in gastric cancer, were confirmed by RT-PCR.
No associated publication
Sex, Age
View SamplesThe project had 2 goals:
Pooling samples within microarray studies: a comparative analysis of rat liver transcription response to prototypical toxicants.
No sample metadata fields
View SamplesDespite investment in toxicogenomics, nonclinical safety studies are still used to predict clinical liabilities for new drug candidates. Network-based approaches for genomic analysis help overcome challenges with whole-genome transcriptional profiling using limited numbers of treatments for phenotypes of interest. Herein, we apply co-expression network analysis to safety assessment using rat liver gene expression data to define 415 modules, exhibiting unique transcriptional control, organized in a visual representation of the transcriptome (the TXG-MAP). Accounting for the overall transcriptional activity resulting from treatment, we explain mechanisms of toxicity and predict distinct toxicity phenotypes using module associations. We demonstrate that early network responses compliment traditional histology-based assessment in predicting outcomes for longer studies and identify a novel mechanism of hepatotoxicity involving endoplasmic reticulum stress and Nrf2 activation. Module-based molecular subtypes of cholestatic injury derived using rat translate to human. Moreover, compared to gene-level analysis alone, combining module and gene-level analysis performed in sequence identifies significantly more phenotype-gene associations, including established and novel biomarkers of liver injury.
Toxicogenomic module associations with pathogenesis: a network-based approach to understanding drug toxicity.
Sex, Specimen part
View SamplesIn addition to immunodeficiency, host mice for chimeric mice with highly humanized liver should have hepatic malfunction in order to allow higher replacement rate of human hepatocytes in the liver. Urokinase-type plasminogen activator (uPA) whole gene transfer is often employed to achieve hepatic malfunction in the host mice.
No associated publication
Specimen part
View SamplesThe discovery of mammalian cardiac progenitor cells has suggested that the heart consists of not only terminally differentiated beating cardiomyocytes, but also a population of self-renewing stem cells with the potential to generate new cardiomyocytes (Anderson, Self et al. 2007; Bearzi, Rota et al. 2007; Wu, Chien et al. 2008). A consequence of longevity is continual exposure to environmental and xenobiotic stresses, and recent literature suggests that hematopoietic stem cell pools tightly control cell health through upregulation of the integrated stress response and consequent cellular mechanisms such as apoptosis. However, whether or not this biological response is conserved in progenitor cells for later lineages of tissue specific stem cells is not well understood. Using human induced pluripotent stem cells (iPSC) of both cardiac progenitor and mature cardiomyocyte lineages, we found that the integrated stress response was upregulated in the iPSC cardiac progenitors leading to an increased sensitivity for apoptosis relative to the mature cardiomyocytes. Of interest, C/EBP homologous protein (CHOP) signaling plays a mechanistic role in the cell death phenotype observed in iPSC progenitors, by which depletion of CHOP prevents cell death following cellular stress by thapsigargin exposure. Our studies suggest that the integrated stress response plays a unique role in maintaining iPSC cardiac progenitor cellular integrity by removing unhealthy cells via apoptosis following environmental and xenobiotic stresses, thus preventing differentiation and self-renewal of damaged cells.
The Integrated Stress Response Regulates Cell Health of Cardiac Progenitors.
Specimen part, Treatment
View SamplesChimeric mice with humanized livers are considered a useful animal model for predicting human drug metabolism and toxicity. In this study, the characteristics of fresh h-hepatocytes (cFHHs, PXB-cells®) isolated from chimeric mice (PXB-mice®) were evaluated in vitro to confirm their utility for drug development. The cFHHs cultured at high density (2.13 × 10^5 cells/cm2) displayed stable production of human albumin and cytochrome P450 (CYP) 3A activities for at least 21 days. The mRNA expression levels of 10 of 13 CYPs, UDP-glucuronosyltransferase (UGP), and transporters were maintained at >10% of the levels of freshly isolated cFHHs after 21 days. From 7-days cultured cFHHs at high density, many bile canaliculi were observed between cFHHs, and the accumulation of multidrug resistance-associated protein (MRP2) and bile salt export pump (BSEP) substrates in these bile canaliculi was clearly inhibited by cyclosporin A.
Culture density contributes to hepatic functions of fresh human hepatocytes isolated from chimeric mice with humanized livers: Novel, long-term, functional two-dimensional in vitro tool for developing new drugs.
Specimen part
View SamplesTranscriptome analysis of partially degraded and fragmented RNA samples from mus musculus gut
No associated publication
Sex, Specimen part, Treatment
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