| 1. |
- Zamora, Juan Carlos, et al.
(författare)
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Considerations and consequences of allowing DNA sequence data as types of fungal taxa
- 2018
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Ingår i: IMA Fungus. - : INT MYCOLOGICAL ASSOC. - 2210-6340 .- 2210-6359. ; 9:1, s. 167-185
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Tidskriftsartikel (refereegranskat)abstract
- Nomenclatural type definitions are one of the most important concepts in biological nomenclature. Being physical objects that can be re-studied by other researchers, types permanently link taxonomy (an artificial agreement to classify biological diversity) with nomenclature (an artificial agreement to name biological diversity). Two proposals to amend the International Code of Nomenclature for algae, fungi, and plants (ICN), allowing DNA sequences alone (of any region and extent) to serve as types of taxon names for voucherless fungi (mainly putative taxa from environmental DNA sequences), have been submitted to be voted on at the 11th International Mycological Congress (Puerto Rico, July 2018). We consider various genetic processes affecting the distribution of alleles among taxa and find that alleles may not consistently and uniquely represent the species within which they are contained. Should the proposals be accepted, the meaning of nomenclatural types would change in a fundamental way from physical objects as sources of data to the data themselves. Such changes are conducive to irreproducible science, the potential typification on artefactual data, and massive creation of names with low information content, ultimately causing nomenclatural instability and unnecessary work for future researchers that would stall future explorations of fungal diversity. We conclude that the acceptance of DNA sequences alone as types of names of taxa, under the terms used in the current proposals, is unnecessary and would not solve the problem of naming putative taxa known only from DNA sequences in a scientifically defensible way. As an alternative, we highlight the use of formulas for naming putative taxa (candidate taxa) that do not require any modification of the ICN.
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| 2. |
- Ghosheh, Nidal, 1975-, et al.
(författare)
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Human Pluripotent Stem Cell-Derived Hepatocytes Show Higher Transcriptional Correlation with Adult Liver Tissue than with Fetal Liver Tissue
- 2020
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 5:10, s. 4816-4827
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cell-derived hepatocytes (hPSC-HEP) display many properties of mature hepatocytes, including expression of important genes of the drug metabolizing machinery, glycogen storage, and production of multiple serum proteins. To this date, hPSC-HEP do not, however, fully recapitulate the complete functionality of in vivo mature hepatocytes. In this study, we applied versatile bioinformatic algorithms, including functional annotation and pathway enrichment analyses, transcription factor binding-site enrichment, and similarity and correlation analyses, to datasets collected from different stages during hPSC-HEP differentiation and compared these to developmental stages and tissues from fetal and adult human liver. Our results demonstrate a high level of similarity between the in vitro differentiation of hPSC-HEP and in vivo hepatogenesis. Importantly, the transcriptional correlation of hPSC-HEP with adult liver (AL) tissues was higher than with fetal liver (FL) tissues (0.83 and 0.70, respectively). Functional data revealed mature features of hPSC-HEP including cytochrome P450 enzymes activities and albumin secretion. Moreover, hPSC-HEP showed expression of many genes involved in drug absorption, distribution, metabolism, and excretion. Despite the high similarities observed, we identified differences of specific pathways and regulatory players by analyzing the gene expression between hPSC-HEP and AL. These findings will aid future intervention and improvement of in vitro hepatocyte differentiation protocol in order to generate hepatocytes displaying the complete functionality of mature hepatocytes. Finally, on the transcriptional level, our results show stronger correlation and higher similarity of hPSC-HEP to AL than to FL. In addition, potential targets for further functional improvement of hPSC-HEP were also identified.
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| 3. |
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Andersson, Tommy D., 1947, et al.
(författare)
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Iceland and the resumption of whaling: An empirical study of the attitudes of international tourists and whale-watch tour operators
- 2012
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Ingår i: Whale-Watching: Sustainable Tourism and Ecological Management. - Cambridge : Cambridge university press. - 9781139018166 ; , s. 95-109
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Bokkapitel (refereegranskat)abstract
- This chapter investigates how the resumption of Icelandic whaling has impacted the whale-watching tourism industry in Iceland viewed both from a demand side and a supply side. The impact on international tourists and domestic whale-watching tour operators’ attitudes were subjects of a case study from Iceland in 2007. After an introduction to Icelandic whale-watching and the Icelandic whaling situation, the results of this case study are presented. In the concluding section the development of whale-watching tourism in Iceland from 1995 to 2009 is viewed and analysed through these two perspectives. Whaling versus the whale-watching tourism industry For a number of reasons, the coexistence of whaling and whale-watching has been described as incompatible (Hoyt & Hvenegaard, 2002). Removal of whales and disturbances or changes to their regular activities are direct effects of whaling. Whaling will thus reduce the number of existing whales for whale-watching at the same time as it can cause avoidance responses to boats in several ways, such as increases in dive intervals (Baker et al., 1988; MacGibbon, 1991; Janik & Thompson, 1996) and changes in movement and direction (Edds & MacFarlane, 1987; Salvado et al., 1992; Bejder et al., 1999; Nowacek et al., 2001) which are caused by the presence and navigation of vessels on the water in proximity to animals (Constantine, 2001). Other potential implications of the coexistence are negative attitudes towards the destination image by whale-watchers as well as other tourists. There are, however, some proponents of the Icelandic resumption of commercial whaling who say that it is possible for commercial whaling and whale-watching to coexist and that money can be gained from both whaling and whale-watching (e.g. Moyle & Evans, 2001 cited in Parsons & Rawles, 2003). In Iceland and Norway, the whale-watching industry exists side by side with the whaling industry. © Cambridge University Press 2014.
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| 9. |
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| 10. |
- Berg, Gertrud, 1944, et al.
(författare)
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Development of severe thyroid-associated ophthalmopathy in a patient with disseminated thyroid cancer treated with recombinant human thyrotropin/radioiodine and retinoic acid.
- 2005
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Ingår i: Thyroid : official journal of the American Thyroid Association. - : Mary Ann Liebert Inc. - 1050-7256. ; 15:12, s. 1389-94
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Tidskriftsartikel (refereegranskat)abstract
- We present a case in which a patient with disseminated well-differentiated papillary thyroid cancer developed severe thyroid-associated ophthalmopathy. Eight years after initial surgery and ablative radioiodine therapy the patient was found to have multiple pulmonary metastases. The metastases showed poor uptake of radioiodine. An attempt was made to use 13-cis-retinoic acid in order to achieve a redifferentiation of the thyroid cancer cells before recombinant human thyrotropin (rhTSH) stimulated radioiodine therapy. The treatment did not improve the uptake of radioiodine. However, approximately 2 weeks after completion of the treatment the patient experienced discomfort in her eyes and then over the next months she developed a severe ophthalmopathy. The analyses of TSH receptor antibodies and S-thyroglobulin simultaneously showed a pronounced increase. An association between therapy given and severe ophthalmopathy cannot be excluded.
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| 11. |
- Brolen, Gabriella, et al.
(författare)
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Hepatocyte-like cells derived from human embryonic stem cells specifically via definitive endoderm and a progenitor stage
- 2010
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Ingår i: Journal of Biotechnology. - : Elsevier BV. - 1873-4863 .- 0168-1656. ; 145:3, s. 284-294
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic stem cells offer a potential unlimited supply for functional hepatocytes, since they can differentiate into hepatocyte-like cells displaying a characteristic hepatic morphology and expressing various hepatic markers. These cells could be used in various applications such as studies of drug metabolism and hepatotoxicity, which however, would require a significant expression of drug metabolizing enzymes. To derive these cells we use a stepwise differentiation protocol where growth- and maturation factors are added. The first phase involves the formation of definitive endoderm. Next, these cells are treated with factors known to promote the induction and proliferation towards hepatic progenitor cell types. In the last phase the cells are terminally differentiated and maturated into functional hepatocyte-like cells. The cultures were characterized by analysis of endodermal or hepatic markers and compared to cultures derived without induction via definitive endoderm. Hepatic functions such as urea secretion, glycogen storage, indocyanine green uptake and secretion, and cytochrome P450-expression and activity were evaluated. The DE-Hep showed a hepatocyte morphology with sub-organized cells and exhibited many liver-functions including transporter activity and capacity to metabolize drugs specific for important cytochrome P450 sub-families. This represents an importantstep in differentiation of hESC into functional hepatocytes. (C) 2009 Elsevier B.V. All rights reserved.
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| 12. |
- Casas Garcia, Belén, et al.
(författare)
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Integrated experimental-computational analysis of a HepaRG liver-islet microphysiological system for human-centric diabetes research
- 2022
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 17:10
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Tidskriftsartikel (refereegranskat)abstract
- Microphysiological systems (MPS) are powerful tools for emulating human physiology and replicating disease progression in vitro. MPS could be better predictors of human outcome than current animal models, but mechanistic interpretation and in vivo extrapolation of the experimental results remain significant challenges. Here, we address these challenges using an integrated experimental-computational approach. This approach allows for in silico representation and predictions of glucose metabolism in a previously reported MPS with two organ compartments (liver and pancreas) connected in a closed loop with circulating medium. We developed a computational model describing glucose metabolism over 15 days of culture in the MPS. The model was calibrated on an experiment-specific basis using data from seven experiments, where HepaRG single-liver or liver-islet cultures were exposed to both normal and hyperglycemic conditions resembling high blood glucose levels in diabetes. The calibrated models reproduced the fast (i.e. hourly) variations in glucose and insulin observed in the MPS experiments, as well as the long-term (i.e. over weeks) decline in both glucose tolerance and insulin secretion. We also investigated the behaviour of the system under hypoglycemia by simulating this condition in silico, and the model could correctly predict the glucose and insulin responses measured in new MPS experiments. Last, we used the computational model to translate the experimental results to humans, showing good agreement with published data of the glucose response to a meal in healthy subjects. The integrated experimental-computational framework opens new avenues for future investigations toward disease mechanisms and the development of new therapies for metabolic disorders.
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| 13. |
- Cederholm, Tommy, et al.
(författare)
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Polymorphisms in cytokine genes influence long-term survival differently in elderly male and female patients
- 2007
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 262:2, s. 215-223
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Tidskriftsartikel (refereegranskat)abstract
- Objectives. We asked if single nucleotide polymorphisms (SNP) in inflammatory cytokine genes related to 3-year survival in ill elderly subjects and if genotypes differed between the elderly and a younger control population. Design. Prospective observational study. Setting. Two geriatric departments at a university hospital. Subjects. Eighty three acutely admitted geriatric patients (83 ± 7 year, 70% women) and 207 young healthy subjects (40 ± 1 year, 37% women) were included. Outcome measures. Single nucleotide polymorphisms in the genes of tumour necrosis factor (TNF)-α–308 G/A, interleukin (IL)-1β–511 C/T, IL-6–174 G/C and IL-10–1082 A/G were analysed. In the geriatric patients SNP in lymphotoxin (LT)-α +252 G/A and serum levels of TNF-α, IL-6, IL-10, soluble IL-I receptor(R)II were also determined, as well as the 3-year mortality. Results. The allele distribution did not differ significantly between the elderly and the young. In the female elderly, 3-year survival was doubled (P < 0.05) in those with the high-producing genotypes of IL-6 –174 GG and TNF-α -308 GA compared with those with low-producing alleles. In contrast, men with high-producing LT-α +252 AA and IL-1β–511 CT&TT genotypes displayed halved 3-year survival (P < 0.05) compared with those with low-producing genotypes, whereas possession of the high-producing IL-10 –1082 GG genotype favoured survival. Serum IL-10 was higher in the high-producing IL-10 genotype in females. Conclusion. As high-producing IL-6 –174 genotype favoured 3-year survival in women, whereas the likewise high-producing LT-α +252 and IL-1β -511 genotypes were associated with poor survival in men, we conclude that the specific genotypes, in association with gender, may act as determinants for survival in elderly patients.
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| 14. |
- Ekström, Elin, et al.
(författare)
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WNT5A induces release of exosomes containing pro-angiogenic and immunosuppressive factors from malignant melanoma cells
- 2014
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Ingår i: Molecular Cancer. - : Springer Science and Business Media LLC. - 1476-4598. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Background: Wnt proteins are important for developmental processes and certain diseases. WNT5A is a non-canonical Wnt protein that previously has been shown to play a role in the progression of malignant melanoma. High expression of WNT5A in melanoma tumors correlates to formation of distant metastasis and poor prognosis. This has partly been described by the findings that WNT5A expression in melanoma cell lines increases migration and invasion. Methods: Malignant melanoma cell lines were treated with rWNT5A or WNT5A siRNA, and mRNA versus protein levels of soluble mediators were measured using RT-PCR, cytokine bead array and ELISA. The induced signaling pathways were analyzed using inhibitors, Rho-GTPase pull down assays and western blot. Ultracentrifugation and electron microscopy was used to analyze microvesicles. Gene expression microarray data obtained from primary malignant melanomas was used to verify our data. Results: We show that WNT5A signaling induces a Ca2+-dependent release of exosomes containing the immunomodulatory and pro-angiogenic proteins IL-6, VEGF and MMP2 in melanoma cells. The process was independent of the transcriptional machinery and depletion of WNT5A reduced the levels of the exosome-derived proteins. The WNT5A induced exosomal secretion was neither affected by Tetanus toxin nor Brefeldin A, but was blocked by the calcium chelator Bapta, inhibited by a dominant negative version of the small Rho-GTPase Cdc42 and was accompanied by cytoskeletal reorganization. Co-cultures of melanoma/endothelial cells showed that depletion of WNT5A in melanoma cells decreased endothelial cell branching, while stimulation of endothelial cells with isolated rWNT5A-induced melanoma exosomes increased endothelial cell branching in vitro. Finally, gene expression data analysis of primary malignant melanomas revealed a correlation between WNT5A expression and the angiogenesis marker ESAM. Conclusions: These data indicate that WNT5A has a broader function on tumor progression and metastatic spread than previously known; by inducing exosome-release of immunomodulatory and pro-angiogenic factors that enhance the immunosuppressive and angiogenic capacity of the tumors thus rendering them more aggressive and more prone to metastasize.
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| 15. |
- Englund, Gunilla, et al.
(författare)
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Cytochrome P450 Inhibitory Properties of Common Efflux Transporter Inhibitors
- 2014
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:3, s. 441-447
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Tidskriftsartikel (refereegranskat)abstract
- Drug transporter inhibitors are important tools to elucidate the contribution of transporters to drug disposition both in vitro and in vivo. These inhibitors are often unselective and affect several transporters as well as drug metabolizing enzymes, which can make experimental results difficult to interpret with confidence. We therefore tested 14 commonly used P-glycoprotein (P-gp), breast cancer resistance protein (BCRP), and multidrug-resistance associated protein (MRP) inhibitors as inhibitors of cytochrome P450 (P450) enzyme activities using recombinant enzymes. A subset of P-gp and/or CYP3A inhibitors were selected (cyclosporin A, elacridar, ketoconazole, quinidine, reserpine, and tacrolimus) for a comparison of P450 inhibition in human microsomes and hepatocytes. Most P-gp inhibitors showed CYP3A4 inhibition, with potencies often in a similar range as their P-gp inhibition, as well as less potent CYP2C19 inhibition. Other P450 enzymes were not strongly inhibited except a few cases of CYP2D6 inhibition. MRP and BCRP inhibitors showed limited P450 inhibition. Some inhibitors showed less P450 inhibition in human hepatocytes than human liver microsomes, for example, elacridar, probably due to differences in binding, permeability limitations, or active, P-gp mediated efflux of the inhibitor from the hepatocytes. Quinidine was a potent P450 inhibitor in hepatocytes but only showed weak inhibition in microsomes. Quinidine shows an extensive cellular uptake, which may potentiate intracellular P450 inhibition. Elacridar, described as a potent and selective P-gp inhibitor, displayed modest P450 inhibition in this study and is thus a useful model inhibitor to define the role of P-gp in drug disposition without interference with other processes.
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| 16. |
- Flondell, Magnus, et al.
(författare)
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Vibration thresholds in carpal tunnel syndrome assessed by multiple frequency vibrometry : a case-control study
- 2017
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Ingår i: Journal of Occupational Medicine and Toxicology. - : Springer Science and Business Media LLC. - 1745-6673. ; 12:34, s. 34-34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Carpal tunnel syndrome (CTS) is the most common compression neuropathy, but there is no gold standard for establishing the diagnosis. The ability to feel vibrations in the fingertips is dependent on the function in cutaneous receptors and afferent nerves. Our aim was to investigate vibration perception thresholds (VPTs) in patients with CTS using multi-frequency vibrometry.Methods: Sixty-six patients (16 men and 50 women) with CTS, diagnosed from clinical signs and by electroneurography, and 66 matched healthy controls were investigated with multi-frequency vibrometry. The VPTs were assessed at seven frequencies (8, 16, 32, 64, 125, 250, and 500 Hz) in the index finger and little finger bilaterally. The severity of the CTS was graded according to Padua and the patient's subjective symptoms were graded according to the Boston carpal tunnel questionnaire. Touch thresholds were assessed using the Semmes-Weinstein monofilaments.Results: Patients with CTS had significantly higher VPTs at all frequencies in the index finger and in 6 out of 7 frequencies in the little finger compared to the controls. However, the VPT was not worse in patients with more severe CTS. Patients with unilateral CTS showed significantly higher VPTs in the affected hand. There were no correlations between VPTs and electrophysiological parameters, subjective symptoms, or touch threshold.Conclusions: Patients with CTS had impaired VPTs at all frequencies compared to the controls. Since the VPTs are dependent on function in peripheral receptors and their afferent nerves, multi-frequency vibrometry could possibly lead to diagnosis of CTS.
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| 17. |
- Holmgren, Gustav, et al.
(författare)
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Long-Term Chronic Toxicity Testing Using Human Pluripotent Stem Cell-Derived Hepatocytes
- 2014
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Ingår i: Drug Metabolism and Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:9, s. 1401-1406
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Tidskriftsartikel (refereegranskat)abstract
- Human pluripotent stem cells (hPSC) have the potential to become important tools for the establishment of new models for in vitro drug testing of, for example, toxicity and pharmacological effects. Late-stage attrition in the pharmaceutical industry is to a large extent caused by selection of drug candidates using nonpredictive preclinical models that are not clinically relevant. The current hepatic in vivo and in vitro models show clear limitations, especially for studies of chronic hepatotoxicity. For these reasons, we evaluated the potential of using hPSC-derived hepatocytes for long-term exposure to toxic drugs. The differentiated hepatocytes were incubated with hepatotoxic compounds for up to 14 days, using a repeated-dose approach. The hPSC-derived hepatocytes became more sensitive to the toxic compounds after extended exposures and, in addition to conventional cytotoxicity, evidence of phospholipidosis and steatosis was also observed in the cells. This is, to the best of our knowledge, the first report of a long-term toxicity study using hPSC-derived hepatocytes, and the observations support further development and validation of hPSC-based toxicity models for evaluating novel drugs, chemicals, and cosmetics.
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| 18. |
- Lundquist, Patrik, et al.
(författare)
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Functional ATP-Binding Cassette Drug Efflux Transporters in Isolated Human and Rat Hepatocytes Significantly Affect Assessment of Drug Disposition
- 2014
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:3, s. 448-458
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Tidskriftsartikel (refereegranskat)abstract
- Freshly isolated hepatocytes are considered the gold standard for in vitro studies of hepatic drug disposition. To ensure a reliable supply of cells, cryopreserved human hepatocytes are often used. ABC-superfamily drug efflux transporters are key elements in hepatic drug disposition. These transporters are often considered lost after isolation of hepatocytes. In the present study, the expression and activity of ABC transporters BCRP, BSEP, P-gp, MRP2, MRP3, and MRP4 in human and rat cryopreserved hepatocytes were investigated. In commercially available human cryopreserved hepatocytes, all drug efflux transporters except human BCRP (hBCRP) exhibited similar expression levels as in fresh liver biopsies. Expression levels of hBCRP were 60% lower in cryopreserved human hepatocytes than in liver tissue, which could lead to, at most, a 2.5-fold reduction in hBCRP-mediated efflux. Fresh rat hepatocytes showed significantly lower levels of rat BCRP compared with liver expression levels; expression levels of other ABC transporters were unchanged. ABC transporters in human cryopreserved cells were localized to the plasma membrane. Functional studies could demonstrate P-gp and BCRP activity in both human cryopreserved and fresh rat hepatocytes. Inhibiting P-gp-mediated efflux by elacridar in in vitro experiments significantly decreased fexofenadine efflux from hepatocytes, resulting in an increase in apparent fexofenadine uptake. The results from the present study clearly indicate that ABC transporter-mediated efflux in freshly isolated as well as cryopreserved rat and human hepatocytes should be taken into account in in vitro experiments used for modeling of drug metabolism and disposition.
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| 19. |
- Lundquist, Patrik, et al.
(författare)
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Prediction of In Vivo Rat Biliary Drug Clearance from an In Vitro Hepatocyte Efflux Model
- 2014
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:3, s. 459-468
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Tidskriftsartikel (refereegranskat)abstract
- Well-established techniques are available to predict in vivo hepatic uptake and metabolism from in vitro data, but predictive models for biliary clearance remain elusive. Several studies have verified the expression and activity of ATP-binding cassette (ABC) efflux transporters central to biliary clearance in freshly isolated rat hepatocytes, raising the possibility of predicting biliary clearance from in vitro efflux measurements. In the present study, short-term plated rat hepatocytes were evaluated as a model to predict biliary clearance from in vitro efflux measurements before major changes in transporter expression known to take place in long-term hepatocyte cultures. The short-term cultures were carefully characterized for their uptake and metabolic properties using a set of model compounds. In vitro efflux was studied using digoxin, fexofenadine, napsagatran, and rosuvastatin, representing compounds with over 100-fold differences in efflux rates in vitro and 60-fold difference in measured in vivo biliary clearance. The predicted biliary clearances from short-term plated rat hepatocytes were within 2-fold of measured in vivo values. As in vitro efflux includes both basolateral and canalicular effluxes, pronounced basolateral efflux may introduce errors in predictions for some compounds. In addition, in vitro rat hepatocyte uptake rates corrected for simultaneous efflux predicted rat in vivo hepatic clearance of the biliary cleared compounds with less than 2-fold error. Short-term plated hepatocytes could thus be used to quantify hepatocyte uptake, metabolism, and efflux of compounds and considerably improve the prediction of hepatic clearance, especially for compounds with a large biliary clearance component.
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| 20. |
- Lundquist, Patrik, et al.
(författare)
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The Impact of Solute Carrier (SLC) Drug Uptake Transporter Loss in Human and Rat Cryopreserved Hepatocytes on Clearance Predictions
- 2014
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 42:3, s. 469-480
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Tidskriftsartikel (refereegranskat)abstract
- Cryopreserved hepatocytes are often used as a convenient tool in studies of hepatic drug metabolism and disposition. In this study, the expression and activity of drug transporters in human and rat fresh and cryopreserved hepatocytes was investigated. In human cryopreserved hepatocytes, Western blot analysis indicated that protein expression of the drug uptake transporters [human Na+-taurocholate cotransporting polypeptide (NTCP), human organic anion transporting polypeptides (OATPs), human organic anion transporters, and human organic cation transporters (OCTs)] was considerably reduced compared with liver tissue. In rat cryopreserved cells, the same trend was observed but to a lesser extent. Several rat transporters were reduced as a result of both isolation and cryopreservation procedures. Immunofluorescence showed that a large portion of remaining human OATP1B1 and OATP1B3 transporters were internalized in human cryopreserved hepatocytes. Measuring uptake activity using known substrates of OATPs, OCTs, and NTCP showed decreased activity in cryopreserved as compared with fresh hepatocytes in both species. The reduced uptake in cryopreserved hepatocytes limited the in vitro metabolism of several AstraZeneca compounds. A retrospective analysis of clearance predictions of AstraZeneca compounds suggested systematic lower clearance predicted using metabolic stability data from human cryopreserved hepatocytes compared with human liver microsomes. This observation is consistent with a loss of drug uptake transporters in cryopreserved hepatocytes. In contrast, the predicted metabolic clearance from fresh rat hepatocytes was consistently higher than those predicted from liver microsomes, consistent with retention of uptake transporters. The uptake transporters, which are decreased in cryopreserved hepatocytes, may be rate-limiting for the metabolism of the compounds and thus be one explanation for underpredictions of in vivo metabolic clearance from cryopreserved hepatocytes.
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| 21. |
- Mandenius, Carl-Fredrik, et al.
(författare)
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Toward Preclinical Predictive Drug Testing for Metabolism and Hepatotoxicity by Using In Vitro Models Derived from Human Embryonic Stem Cells and Human Cell Lines - A Report on the Vitrocellomics EU-project
- 2011
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Ingår i: ATLA-ALTERNATIVES TO LABORATORY ANIMALS. - : Fund for Replacement of Animals in Medical Experiments; 1999. - 0261-1929 .- 2632-3559. ; 39:2, s. 147-171
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Tidskriftsartikel (refereegranskat)abstract
- Drug-induced liver injury is a common reason for drug attrition in late clinical phases, and even for post-launch withdrawals. As a consequence, there is a broad consensus in the pharmaceutical industry, and within regulatory authorities, that a significant improvement of the current in vitro test methodologies for accurate assessment and prediction of such adverse effects is needed. For this purpose, appropriate in vivo-like hepatic in vitro models are necessary, in addition to novel sources of human hepatocytes. In this report, we describe recent and ongoing research toward the use of human embryonic stem cell (hESC)-derived hepatic cells, in conjunction with new and improved test methods, for evaluating drug metabolism and hepatotoxicity. Recent progress on the directed differentiation of human embryonic stem cells to the functional hepatic phenotype is reported, as well as the development and adaptation of bioreactors and toxicity assay technologies for the testing of hepatic cells. The aim of achieving a testing platform for metabolism and hepatotoxicity assessment, based on hESC-derived hepatic cells, has advanced markedly in the last 2-3 years. However, great challenges still remain, before such new test systems could be routinely used by the industry. In particular, we give an overview of results from the Vitrocellomics project (EU Framework 6) and discuss these in relation to the current state-of-the-art and the remaining difficulties, with suggestions on how to proceed before such in vitro systems can be implemented in industrial discovery and development settings and in regulatory acceptance.
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| 22. |
- Matsson, Pär, et al.
(författare)
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A Tribute to Professor Per Artursson - Scientist, Explorer, Mentor, Innovator, and Giant in Pharmaceutical Research
- 2021
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier. - 0022-3549 .- 1520-6017. ; 110:1, s. 2-11
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This issue of the Journal of Pharmaceutical Sciences is dedicated to Professor Per Artursson and the groundbreaking contributions he has made and continues to make in the Pharmaceutical Sciences. Per is one of the most cited researchers in his field, with more than 30,000 citations and an h-index of 95 as of September 2020. Importantly, these citations are distributed over the numerous fields he has explored, clearly showing the high impact the research has had on the discipline. We provide a short portrait of Per, with emphasis on his personality, driving forces and the inspirational sources that shaped his career as a world-leading scientist in the field. He is a curious scientist who deftly moves between disciplines and has continued to innovate, expand boundaries, and profoundly impact the pharmaceutical sciences throughout his career. He has developed new tools and provided insights that have significantly contributed to today’s molecular and mechanistic approaches to research in the fields of intestinal absorption, cellular disposition, and exposure-efficacy relationships of pharmaceutical drugs. We want to celebrate these important contributions in this special issue of the Journal of Pharmaceutical Sciences in Per’s honor.
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| 23. |
- Neve, Etienne P A, et al.
(författare)
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Amidoxime Reductase System Containing Cytochrome b5 Type B (CYB5B) and MOSC2 Is of Importance for Lipid Synthesis in Adipocyte Mitochondria
- 2012
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 287:9, s. 6307-6317
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Tidskriftsartikel (refereegranskat)abstract
- Reduction of hydroxylamines and amidoximes is important for drug activation and detoxification of aromatic and heterocyclic amines. Such a reductase system was previously found to be of high activity in adipose tissue and liver, and furthermore, in vitro studies using recombinant truncated and purified enzymes suggested the participation of cytochrome b(5) reductase (CYB5R), cytochrome b(5) (CYB5), and molybdenum cofactor sulfurase C-terminal containing 1 and 2 (MOSC1 and -2). Here, we show that purified rat liver outer mitochondrial membrane contains high amidoxime reductase activity and that MOSC2 is exclusively localized to these membranes. Moreover, using the same membrane fraction, we could show direct binding of a radiolabeled benzamidoxime substrate to MOSC2. Following differentiation of murine 3T3-L1 cells into mature adipocytes, the MOSC2 levels as well as the amidoxime reductase activity were increased, indicating that the enzyme is highly regulated under lipogenic conditions. siRNA-mediated down-regulation of MOSC2 and the mitochondrial form of cytochrome b(5) type B (CYB5B) significantly inhibited the reductase activity in the differentiated adipocytes, whereas down-regulation of MOSC1, cytochrome b(5) type A (CYB5A), CYB5R1, CYB5R2, or CYB5R3 had no effect. Down-regulation of MOSC2 caused impaired lipid synthesis. These results demonstrate for the first time the direct involvement of MOSC2 and CYB5B in the amidoxime reductase activity in an intact cell system. We postulate the presence of a novel reductive enzyme system of importance for lipid synthesis that is exclusively localized to the outer mitochondrial membrane and is composed of CYB5B, MOSC2, and a third unknown component (a CYB5B reductase).
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| 24. |
- Niklasson, Erik, et al.
(författare)
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Assessment of anterior thigh muscle size and fat infiltration using single-slice CT imaging versus automated MRI analysis in adults
- 2022
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Ingår i: British Journal of Radiology. - London, United Kingdom : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 95:1133
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: We examined the longitudinal and cross- sectional relationship between automated MRI-analysis and single-slice axial CT imaging for determining muscle size and muscle fat infiltration (MFI) of the anterior thigh.Methods: Twenty-two patients completing sex-hormone treatment expected to result in muscle hypertrophy (n = 12) and atrophy (n = 10) underwent MRI scans using 2-point Dixon fat/water-separated sequences and CT scans using a system operating at 120 kV and a fixed flux of 100 mA. At baseline and 12 months after, auto- mated volumetric MRI analysis of the anterior thigh was performed bilaterally, and fat-free muscle volume and MFI were computed. In addition, cross-sectional area (CSA) and radiological attenuation (RA) (as a marker of fat infiltration) were calculated from single slice axial CT-images using threshold-assisted planimetry. Linear regression models were used to convert units.Results: There was a strong correlation between MRI- derived fat-free muscle volume and CT-derived CSA (R = 0.91), and between MRI-derived MFI and CT-derived RA (R = −0.81). The 95% limits of agreement were ±0.32 L for muscle volume and ±1.3% units for %MFI. The longi- tudinal change in muscle size and MFI was comparable across imaging modalities.Conclusions: Both automated MRI and single-slice CT-imaging can be used to reliably quantify anterior thigh muscle size and MFI.Advances in knowledge: This is the first study examining the intermodal agreement between automated MRI anal- ysis and CT-image assessment of muscle size and MFI in the anterior thigh muscles. Our results support that both CT- and MRI-derived measures of muscle size and MFI can be used in clinical settings.
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| 25. |
- Ospel, Johanna M., et al.
(författare)
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What is a Challenging Clot? : A DELPHI Consensus Statement from the CLOTS 7.0 Summit
- 2023
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Ingår i: Clinical Neuroradiology. - 1869-1439 .- 1869-1447. ; 33:4, s. 1007-1016
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Tidskriftsartikel (refereegranskat)abstract
- Background: Predicting a challenging clot when performing mechanical thrombectomy in acute stroke can be difficult. One reason for this difficulty is a lack of agreement on how to precisely define these clots. We explored the opinions of stroke thrombectomy and clot research experts regarding challenging clots, defined as difficult to recanalize clots by endovascular approaches, and clot/patient features that may be indicative of such clots. Methods: A modified DELPHI technique was used before and during the CLOTS 7.0 Summit, which included experts in thrombectomy and clot research from different specialties. The first round included open-ended questions and the second and final rounds each consisted of 30 closed-ended questions, 29 on various clinical and clot features, and 1 on number of passes before switching techniques. Consensus was defined as agreement ≥ 50%. Features with consensus and rated ≥ 3 out of 4 on the certainty scale were included in the definition of a challenging clot. Results: Three DELPHI rounds were performed. Panelists achieved consensus on 16/30 questions, of which 8 were rated 3 or 4 on the certainty scale, namely white-colored clots (mean certainty score 3.1), calcified clots under histology (3.7) and imaging (3.7), stiff clots (3.0), sticky/adherent clots (3.1), hard clots (3.1), difficult to pass clots (3.1) and clots that are resistant to pulling (3.0). Most panelists considered switching endovascular treatment (EVT) techniques after 2–3 unsuccessful attempts. Conclusion: This DELPHI consensus identified 8 distinct features of a challenging clot. The varying degree of certainty amongst the panelists emphasizes the need for more pragmatic studies to enable accurate a priori identification of such occlusions prior to EVT.
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| 26. |
- Otten, Julia, 1973-, et al.
(författare)
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Exercise Training Adds Cardiometabolic Benefits of a Paleolithic Diet in Type 2 Diabetes Mellitus
- 2019
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Ingår i: Journal of the American Heart Association. - : Wiley-Blackwell. - 2047-9980. ; 8:2
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Tidskriftsartikel (refereegranskat)abstract
- Background: The accumulation of myocardial triglycerides and remodeling of the left ventricle are common features in type 2 diabetes mellitus and represent potential risk factors for the development of diastolic and systolic dysfunction. A few studies have investigated the separate effects of diet and exercise training on cardiac function, but none have investigated myocardial changes in response to a combined diet and exercise intervention. This 12-week randomized study assessed the effects of a Paleolithic diet, with and without additional supervised exercise training, on cardiac fat, structure, and function.Methods and Results: Twenty-two overweight and obese subjects with type 2 diabetes mellitus were randomized to either a Paleolithic diet and standard-care exercise recommendations ( PD ) or to a Paleolithic diet plus supervised exercise training 3 hours per week ( PD - EX ). This study includes secondary end points related to cardiac structure and function, ie, myocardial triglycerides levels, cardiac morphology, and strain were measured using cardiovascular magnetic resonance, including proton spectroscopy, at baseline and after 12 weeks. Both groups showed major favorable metabolic changes. The PD - EX group showed significant decreases in myocardial triglycerides levels (-45%, P=0.038) and left ventricle mass to end-diastolic volume ratio (-13%, P=0.008) while the left ventricle end-diastolic volume and stroke volume increased significantly (+14%, P=0.004 and +17%, P=0.008, respectively). These variables were unchanged in the PD group.Conclusions: Exercise training plus a Paleolithic diet reduced myocardial triglycerides levels and improved left ventricle remodeling in overweight/obese subjects with type 2 diabetes mellitus.Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 01513798.
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| 27. |
- Persson, Kajsa P., et al.
(författare)
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Evaluation of Human Liver Slices and Reporter Gene Assays as Systems for Predicting the Cytochrome P450 Induction Potential of Drugs in Vivo in Humans
- 2006
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Ingår i: Pharmaceutical research. - New York : Springer. - 0724-8741 .- 1573-904X. ; 23:1, s. 56-69
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe aim of the study was to investigate the feasibility of predicting human in vivo cytochrome P450 (CYP) induction properties of drugs using in vitro methods.MethodsThe CYP induction potential of compounds was tested in human liver slices and in reporter gene assays for the aryl hydrocarbon receptor (AhR) and the pregnane X receptor (PXR).ResultsIn human liver slices, CYP activities decreased dramatically over the experimental period, whereas mRNA levels could reliably be used to investigate CYP1A, 2C9, and 3A4 induction. However, the interindividual variations and demanding experimentation limit the use of liver slices in screening programs. Reporter gene assays are robust and reliable assays, amenable to high throughput screening. Several compounds activated AhR. The relevance of this activation, however, needs to be further investigated since there are no clear reports on drugs inducing CYP1A in vivo. The results from the PXR assay could be used to correctly classify compounds with known CYP3A induction properties when relating in vivo AUCtot to PXR EC50 values.ConclusionsLiver slices are a valuable model to study the regulation of a larger number of enzymes by single compounds. The PXR reporter gene assay could be used as a reliable screening method to predict CYP3A induction in vivo. © 2006 Springer Science + Business Media, Inc.
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| 28. |
- Shete, Sanjay, et al.
(författare)
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Genome-wide association study identifies five susceptibility loci for glioma.
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1061-4036 .- 1546-1718. ; 41:8, s. 899-904
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Tidskriftsartikel (refereegranskat)abstract
- To identify risk variants for glioma, we conducted a meta-analysis of two genome-wide association studies by genotyping 550K tagging SNPs in a total of 1,878 cases and 3,670 controls, with validation in three additional independent series totaling 2,545 cases and 2,953 controls. We identified five risk loci for glioma at 5p15.33 (rs2736100, TERT; P = 1.50 x 10(-17)), 8q24.21 (rs4295627, CCDC26; P = 2.34 x 10(-18)), 9p21.3 (rs4977756, CDKN2A-CDKN2B; P = 7.24 x 10(-15)), 20q13.33 (rs6010620, RTEL1; P = 2.52 x 10(-12)) and 11q23.3 (rs498872, PHLDB1; P = 1.07 x 10(-8)). These data show that common low-penetrance susceptibility alleles contribute to the risk of developing glioma and provide insight into disease causation of this primary brain tumor.
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| 29. |
- Sjögren, Erik, et al.
(författare)
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Hepatic disposition of ximelagatran and its metabolites in pig; prediction of the impact of membrane transporters through a simple disposition model
- 2010
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Ingår i: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 27:4, s. 597-607
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The double prodrug ximelagatran is bioconverted, via the intermediates ethylmelagatran and N-hydroxymelagatran, to the direct thrombin inhibitor melagatran. The aims of this study were 1) to investigate the hepatic metabolism and disposition of ximelagatran and the intermediates in pig; and 2) to test a simple in vitro methodology for quantitative investigations of membrane transporters impact on the disposition of metabolized drugs. Methods: Porcine S1 (supernatant fraction obtained by centrifuging at 1000g for 10 min) liver fractions and hepatocytes were incubated in absence and presence of known membrane transporter inhibitors. The in vitro kinetics and disposition were determined by simultaneously fitting of the disappearance of ximelagatran and appearance of ethylmelagatran, N-hydroxymelagatran and melagatran. Results: In S1 liver fractions, the metabolism was significant inhibited by co-incubation of verapamil and ketoconazole but not by erythromycin, quinine and quinidine. The disposition of ximelagatran and the intermediate metabolites in hepatocytes were influenced, to various degrees, by carrier-mediated distribution processes. Conclusion: This work demonstrates that it is possible to obtain profound information of the general mechanisms important in the drug liver disposition with the combination of common in vitro systems and the simple disposition model proposed in this study.
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| 30. |
- Sjögren, Erik, et al.
(författare)
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The multiple depletion curves method provides accurate estimates of intrinsic clearance (CLint), maximum velocity of the metabolic reaction (Vmax), and Michaelis constant (Km) : accuracy and robustness evaluated through experimental data and Monte Carlo simulations
- 2009
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Ingår i: Drug Metabolism And Disposition. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0090-9556 .- 1521-009X. ; 37:1, s. 47-58
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Tidskriftsartikel (refereegranskat)abstract
- The use of multiple depletion curves for the estimation of maximum velocity of the metabolic reaction (V(max)), the Michaelis constant (K(m)), and intrinsic clearance (CL(int)) was thoroughly evaluated by means of experimental data and through a series of Monte Carlo simulations. The enzyme kinetics of seven compounds were determined using the multiple depletion curves method (MDCM), the traditional initial formation rate of metabolite method (IFRMM), and the "in vitro t(1/2)" method, and the parameter estimates that were derived from the three methods were compared. The impact of a change in enzyme activity during the incubation period on the parameter estimates and the possibility to correct for this were also investigated. The MDCM was in good overall agreement with the IFRMM. Correction for a change in enzyme activity was possible and resulted in a better concordance in CL(int) estimates. The robustness of the method in coping with different rates of substrate turnover and variable starting concentrations were also demonstrated through Monte Carlo simulations. Furthermore, the limitations imposed by assumptions inherent in the in vitro t(1/2) method were demonstrated both experimentally and by simulations. This study demonstrates that the MDCM is a robust and efficient method for estimating enzyme kinetic variables with high accuracy and precision. The method may potentially be used in a wide range of applications, from pure enzyme kinetics to in vitro-based predictions of the pharmacokinetics of compounds with multiple and/or unknown metabolic pathways.
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| 31. |
- Ulvestad, Maria, et al.
(författare)
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Drug metabolizing enzyme and transporter protein profiles of hepatocytes derived from human embryonic and induced pluripotent stem cells
- 2013
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Ingår i: Biochemical Pharmacology. - : Elsevier. - 0006-2952 .- 1356-1839 .- 1873-2968. ; 86:5, s. 691-702
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Tidskriftsartikel (refereegranskat)abstract
- Human embryonic and induced pluripotent stem cell-derived hepatocytes (hESC-Hep and hiPSC-Hep) have the potential to provide relevant human in vitro model systems for toxicity testing and drug discovery studies. In this study, the expression and function of important drug metabolizing cytochrome P450 (CYP) enzymes and transporter proteins in hESC-Hep and hiPSC-Hep were compared to cryopreserved human primary hepatocytes (hphep) and HepG2 cells. Overall, CYP activities in hESC-Hep and hiPSC-Hep were much lower than in hphep cultured for 4 h, but CYP1A and 3A activities were comparable to levels in hphep cultured for 48 h (CYP1A: 35% and 26% of 48 h hphep, respectively; CYP3A: 80% and 440% of 48 h hphep, respectively). Importantly, in hESC-Hep and hiPSC-Hep, CYP activities were stable or increasing for at least one week in culture which was in contrast to the rapid loss of CYP activities in cultured hphep between 4 and 48 h after plating. With regard to transporters, in hESC-Hep and hiPSC-Hep, pronounced NTCP activity (17% and 29% of 4 h hphep, respectively) and moderate BSEP activity (6% and 8% of 4 h hphep, respectively) were observed. Analyses of mRNA expression and immunocytochemistry supported the observed CYP and transporter activities and showed expression of additional CYPs and transporters. In conclusion, the stable expression and function of CYPs and transporters in hESC-Hep and hiPSC-Hep for at least one week opens up the possibility to reproducibly perform long term and extensive studies, e.g. chronic toxicity testing, in a stem cell-derived hepatic system. (C) 2013 Elsevier Inc. All rights reserved.
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| 32. |
- Wegler, Christine, et al.
(författare)
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Drug Disposition Protein Quantification in Matched Human Jejunum and Liver From Donors With Obesity
- 2022
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Ingår i: Clinical Pharmacology and Therapeutics. - : John Wiley & Sons. - 0009-9236 .- 1532-6535. ; 111:5, s. 1142-1154
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Tidskriftsartikel (refereegranskat)abstract
- Mathematical models, such as physiologically-based pharmacokinetic models, are used to predict, for example, drug disposition and toxicity. However, populations differ in the abundance of proteins involved in these processes. To improve the building and refinement of such models, they must take into account these interindividual variabilities. In this study, we used global proteomics to characterize the protein composition of jejunum and liver from 37 donors with obesity enrolled in the COCKTAIL study. Liver protein levels from the 37 donors were further compared with those from donors without obesity. We quantified thousands of proteins and could present the expression of several drug-metabolizing enzymes, for the first time, in jejunum, many of which belong to the cytochrome P450 (CYP) (e.g., CYP2U1) and the amine oxidase (flavin-containing) (e.g., monoamine oxidase A (MAOA)) families. Although we show that many metabolizing enzymes had greater expression in liver, others had higher expression in jejunum (such as, MAOA and CES2), indicating the role of the small intestine in extrahepatic drug metabolism. We further show that proteins involved in drug disposition are not correlated in the two donor-matched tissues. These proteins also do not correlate with physiological factors such as body mass index, age, and inflammation status in either tissue. Furthermore, the majority of these proteins are not differently expressed in donors with or without obesity. Nonetheless, interindividual differences were considerable, with implications for personalized prediction models and systems pharmacology.
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| 33. |
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| 34. |
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| 35. |
- Wegler, Christine, et al.
(författare)
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Global variability analysis of mRNA and protein concentrations across and within human tissues
- 2020
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Ingår i: NAR Genomics and Bioinformatics. - : Oxford University Press (OUP). - 2631-9268. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Genes and proteins show variable expression patterns throughout the human body. However, it is not clear whether relative differences in mRNA concentrations are retained on the protein level. Furthermore, inter-individual protein concentration variability within single tissue types has not been comprehensively explored. Here, we used the Gini index for in-depth concentration variability analysis of publicly available transcriptomics and proteomics data, and of an in-house proteomics dataset of human liver and jejunum from 38 donors. We found that the transfer of concentration variability from mRNA to protein is limited, that established ‘reference genes’ for data normalization vary markedly at the protein level, that protein concentrations cover a wide variability spectrum within single tissue types, and that concentration variability analysis can be a convenient starting point for identifying disease-associated proteins and novel biomarkers. Our results emphasize the importance of considering individual concentration levels, as opposed to population averages, for personalized systems biology analysis.
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| 36. |
- Wegler, Christine, et al.
(författare)
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Influence of Proteome Profiles and Intracellular Drug Exposure on Differences in CYP Activity in Donor-Matched Human Liver Microsomes and Hepatocytes
- 2021
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 18:4, s. 1792-1805
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Tidskriftsartikel (refereegranskat)abstract
- Human liver microsomes (HLM) and human hepatocytes (HH) are important in vitro systems for studies of intrinsic drug clearance (CLint) in the liver. However, the CLint values are often in disagreement for these two systems. Here, we investigated these differences in a side-by-side comparison of drug metabolism in HLM and HH prepared from 15 matched donors. Protein expression and intracellular unbound drug concentration (Kpuu) effects on the CLint were investigated for five prototypical probe substrates (bupropion–CYP2B6, diclofenac–CYP2C9, omeprazole–CYP2C19, bufuralol–CYP2D6, and midazolam–CYP3A4). The samples were donor-matched to compensate for inter-individual variability but still showed systematic differences in CLint. Global proteomics analysis outlined differences in HLM from HH and homogenates of human liver (HL), indicating variable enrichment of ER-localized cytochrome P450 (CYP) enzymes in the HLM preparation. This suggests that the HLM may not equally and accurately capture metabolic capacity for all CYPs. Scaling CLint with CYP amounts and Kpuu could only partly explain the discordance in absolute values of CLint for the five substrates. Nevertheless, scaling with CYP amounts improved the agreement in rank order for the majority of the substrates. Other factors, such as contribution of additional enzymes and variability in the proportions of active and inactive CYP enzymes in HLM and HH, may have to be considered to avoid the use of empirical scaling factors for prediction of drug metabolism.
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| 37. |
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| 38. |
- Wegler, Christine, 1986-
(författare)
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Proteomics-informed analysis of drug disposition in the human liver and small intestine
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Orally administered drugs are absorbed in the intestine and generally metabolized in the liver. Therefore, understanding factors determining drug distribution and elimination in these tissues is important. This thesis aimed at using mass spectrometry (MS)-based proteomics and functional studies to better understand in vitro model systems used for drug clearance predictions. Further, it aimed at understanding the changes in drug disposition caused by obesity and gastric bypass surgery (GBP).The study was initiated by investigating factors influencing MS-based protein quantification by comparing results from different proteomics methods, and by studying protein distribution during subcellular fractionation. The largest variability in protein quantification was ascribed to insufficient enrichment from subcellular fractionation, most likely due to collection of the majority of the proteins in the initial fraction of the fractionation protocols.Proteomics and metabolic activity analyses were then used to investigate differences in intrinsic clearance from two commonly used in vitro systems, human liver microsomes and hepatocytes. For some compounds, the faster microsomal metabolism could be explained by a higher available unbound drug concentration and CYP content in the microsomes as compared to in the hepatocytes.Next, inter-individual protein expression variability in human liver and jejunum was explored. This showed that proteins covered a wide inter-individual variability spectrum, in which proteins with low variabilities were associated with essential cellular functions, while many proteins with high variabilities were disease-related.Further, the effects of obesity, GBP, and weight loss on the proteomes of human liver and jejunum were analyzed. After GBP and subsequent weight loss, patients showed lower levels of jejunal proteins involved in inflammatory response and drug metabolism.Finally, proteomics data from patients with and without obesity was combined with parameters from in vitro transport kinetics, and a mechanistic model to predict drug disposition was developed. The model successfully predicted rosuvastatin plasma concentrations in the patients.In conclusion, this thesis has provided insights into factors influencing protein quantification and function in vitro. Furthermore, this thesis demonstrates how proteomics contributes to improved understanding of inter-individual and physiological differences, and how it can be used for in vitro-in vivo scaling of drug clearance.
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| 39. |
- Wegler, Christine, et al.
(författare)
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Proteomics‐Informed Prediction of Rosuvastatin Plasma Profiles in Patients with a Wide Range of Body Weight
- 2021
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Ingår i: Clinical Pharmacology and Therapeutics. - : John Wiley & Sons. - 0009-9236 .- 1532-6535. ; 109:3, s. 762-771
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Tidskriftsartikel (refereegranskat)abstract
- Rosuvastatin is a frequently used probe to study transporter-mediated hepatic uptake. Pharmacokinetic models have therefore been developed to predict transporter impact on rosuvastatin disposition in vivo. However, the interindividual differences in transporter concentrations were not considered in these models, and the predicted transporter impact was compared with historical in vivo data. In this study, we investigated the influence of interindividual transporter concentrations on the hepatic uptake clearance of rosuvastatin in 54 patients covering a wide range of body weight. The 54 patients were given an oral dose of rosuvastatin the day before undergoing gastric bypass or cholecystectomy, and pharmacokinetic (PK) parameters were established from each patient’s individual time-concentration profiles. Liver biopsies were sampled from each patient and their individual hepatic transporter concentrations were quantified. We combined the transporter concentrations with in vitro uptake kinetics determined in HEK293-transfected cells, and developed a semimechanistic model with a bottom-up approach to predict the plasma concentration profiles of the single dose of rosuvastatin in each patient. The predicted PK parameters were evaluated against the measured in vivo plasma PKs from the same 54 patients. The developed model predicted the rosuvastatin PKs within two-fold error for rosuvastatin area under the plasma concentration versus time curve (AUC; 78% of the patients; average fold error (AFE): 0.96), peak plasma concentration (Cmax; 76%; AFE: 1.05), and terminal half-life (t1/2; 98%; AFE: 0.89), and captured differences in the rosuvastatin PKs in patients with the OATP1B1 521T
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| 40. |
- Wegler, Christine, et al.
(författare)
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Variability in Mass Spectrometry-based Quantification of Clinically Relevant Drug Transporters and Drug Metabolizing Enzymes
- 2017
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Ingår i: Molecular Pharmaceutics. - : AMER CHEMICAL SOC. - 1543-8384 .- 1543-8392. ; 14:9, s. 3142-3151
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Tidskriftsartikel (refereegranskat)abstract
- Many different methods are used for mass-spectrometry-based protein quantification in pharmacokinetics and systems pharmacology. It has not been established to what extent the results from these various methods are comparable. Here, we compared six different mass spectrometry-based proteomics methods by measuring the expression of clinically relevant drug transporters and metabolizing enzymes in human liver. Mean protein concentrations were in general quantified to similar levels by methods using whole tissue lysates. Methods using subcellular membrane fractionation gave incomplete enrichment of the proteins. When the enriched proteins were adjusted to levels in whole tissue lysates, they were on average 4 fold lower than those quantified directly in whole tissue lysates. The differences in protein levels were propagated into differences in predictions of hepatic clearance. In conclusion, caution is needed when comparing and applying quantitative proteomics data obtained with different methods, especially since membrane fractionation is common practice for protein quantification used in drug clearance predictions.
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| 41. |
- Wiik, Anna, et al.
(författare)
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Muscle Strength, Size, and Composition Following 12 Months of Gender-affirming Treatment in Transgender Individuals
- 2020
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : ENDOCRINE SOC. - 0021-972X .- 1945-7197. ; 105:3, s. E805-E813
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Tidskriftsartikel (refereegranskat)abstract
- Context. As many sports are divided in male/female categories, governing bodies have formed regulations on the eligibility for transgender individuals to compete in these categories. Yet, the magnitude of change in muscle mass and strength with gender-affirming treatment remains insufficiently explored. Objective. This study explored the effects of gender-affirming treatment on muscle function, size, and composition during 12 months of therapy. Design, settings, participants. In this single-center observational cohort study, untrained transgender women (TW, n = 11) and transgender men (TM, n = 12), approved to start gender-affirming medical interventions, underwent assessments at baseline, 4 weeks after gonadal suppression of endogenous hormones but before hormone replacement, and 4 and 12 months after treatment initiation. Main outcome measures. Knee extensor and flexor strength were assessed at all examination time points, and muscle size and radiological density (using magnetic resonance imaging and computed tomography) at baseline and 12 months after treatment initiation. Results. Thigh muscle volume increased (15%) in TM, which was paralleled by increased quadriceps cross-sectional area (CSA) (15%) and radiological density (6%). In TW, the corresponding parameters decreased by -5% (muscle volume) and -4% (CSA), while density remained unaltered. The TM increased strength over the assessment period, while the TW generally maintained their strength levels. Conclusions. One year of gender-affirming treatment resulted in robust increases in muscle mass and strength in TM, but modest changes in TW. These findings add new knowledge on the magnitude of changes in muscle function, size, and composition with cross-hormone therapy, which could be relevant when evaluating the transgender eligibility rules for athletic competitions.
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