| 1. |
- Alexander, Stephen P. H., et al.
(författare)
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The Concise Guide to PHARMACOLOGY 2023/24: G protein-coupled receptors
- 2023
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Ingår i: BRITISH JOURNAL OF PHARMACOLOGY. - : British pharmacological society. - 0007-1188 .- 1476-5381. ; 180
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Tidskriftsartikel (refereegranskat)abstract
- The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and about 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at . G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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| 2. |
- Balgoma, David, et al.
(författare)
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Orthogonality in Principal Component Analysis Allows the Discovery of Lipids in the Jejunum That Are Independent of Ad Libitum Feeding
- 2022
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Ingår i: Metabolites. - : MDPI. - 2218-1989 .- 2218-1989. ; 12:9
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Tidskriftsartikel (refereegranskat)abstract
- Ad libitum feeding of experimental animals is preferred because of medical relevance together with technical and practical considerations. In addition, ethical committees may require ad libitum feeding. However, feeding affects the metabolism so ad libitum feeding may mask the effects of drugs on tissues directly involved in the digestion process (e.g., jejunum and liver). Despite this effect, principal component analysis has the potential of identifying metabolic traits that are statistically independent (orthogonal) to ad libitum feeding. Consequently, we used principal component analysis to discover the metabolic effects of doxorubicin independent of ad libitum feeding. First, we analyzed the lipidome of the jejunum and the liver of rats treated with vehicle or doxorubicin. Subsequently, we performed principal component analysis. We could identify a principal component associated to the hydrolysis of lipids during digestion and a group of lipids that were orthogonal. These lipids in the jejunum increased with the treatment time and presented a polyunsaturated fatty acid as common structural trait. This characteristic suggests that doxorubicin increases polyunsaturated fatty acids. This behavior agrees with our previous in vitro results and suggests that doxorubicin sensitized the jejunum to ferroptosis, which may partially explain the toxicity of doxorubicin in the intestines.
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| 3. |
- Boud, David, et al.
(författare)
-
Creating a world class program : Reciprocity and constraints in global study.
- 2006
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Ingår i: International Journal of Lifelong Education. - : Informa UK Limited. - 0260-1370 .- 1464-519X. ; 25:6, s. 609-622
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Tidskriftsartikel (refereegranskat)abstract
- The article reflects on the construction of a common Master's programme across four universities located on four continents, in order to explore the role of networks in international educational collaboration. The study draws on the documented processes of the principal members of the programme team. It is presented as a case study of the development of the programme that uses ideas drawn from actor-network theory to draw attention to the conjunction of human and non-human actors that shaped the resulting web-based courses. Constraints arising from major institutional and systemic obstacles were addressed through the effects of the actor-network. The reciprocity of action and de-centring of individual activity made possible through the collaboration enabled the human actors to sustain a level of innovation within their own institutions that would not have been possible through them acting alone.
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| 4. |
- Boud, David, et al.
(författare)
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Making sense of new forms of practice : multiple perspectives in researching an intercultural programme across continents.
- 2006
-
Ingår i: Standing Conference on University Teaching and Research in the Education of Adults,2006.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The focus of the symposium is on researching a programme with multiple sites of practice (in four conutries on four continents), learners distributed across the world and an emphasis on a pedagogy that embeds intercultural understanding. Studies from different perspectives are used to explore research issues in intercultural courses.
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| 5. |
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| 6. |
- Christopoulos, Arthur, et al.
(författare)
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THE CONCISE GUIDE TO PHARMACOLOGY 2021/22: G protein-coupled receptors.
- 2021
-
Ingår i: British journal of pharmacology. - : Wiley. - 1476-5381 .- 0007-1188. ; 178 Suppl 1
-
Forskningsöversikt (refereegranskat)abstract
- The Concise Guide to PHARMACOLOGY 2021/22 is the fifth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of nearly 1900 human drug targets with an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (www.guidetopharmacology.org), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes over 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/bph.15538. G protein-coupled receptors are one of the six major pharmacological targets into which the Guide is divided, with the others being: ion channels, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2021, and supersedes data presented in the 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.
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| 7. |
- Baeten, Lander, et al.
(författare)
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Identifying the tree species compositions that maximize ecosystem functioning in European forests
- 2019
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 56:3, s. 733-744
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Tidskriftsartikel (refereegranskat)abstract
- 1. Forest ecosystem functioning generally benefits from higher tree species richness, but variation within richness levels is typically large. This is mostly due to the contrasting performances of communities with different compositions. Evidence-based understanding of composition effects on forest productivity, as well as on multiple other functions will enable forest managers to focus on the selection of species that maximize functioning, rather than on diversity per se.2. We used a dataset of 30 ecosystem functions measured in stands with different species richness and composition in six European forest types. First, we quantified whether the compositions that maximize annual above-ground wood production (productivity) generally also fulfil the multiple other ecosystem functions (multifunctionality). Then, we quantified the species identity effects and strength of interspecific interactions to identify the "best" and "worst" species composition for multifunctionality. Finally, we evaluated the real-world frequency of occurrence of best and worst mixtures, using harmonized data from multiple national forest inventories.3. The most productive tree species combinations also tended to express relatively high multifunctionality, although we found a relatively wide range of compositions with high- or low-average multifunctionality for the same level of productivity. Monocultures were distributed among the highest as well as the lowest performing compositions. The variation in functioning between compositions was generally driven by differences in the performance of the component species and, to a lesser extent, by particular interspecific interactions. Finally, we found that the most frequent species compositions in inventory data were monospecific stands and that the most common compositions showed below-average multifunctionality and productivity.4. Synthesis and applications. Species identity and composition effects are essential to the development of high-performing production systems, for instance in forestry and agriculture. They therefore deserve great attention in the analysis and design of functional biodiversity studies if the aim is to inform ecosystem management. A management focus on tree productivity does not necessarily trade-off against other ecosystem functions; high productivity and multifunctionality can be combined with an informed selection of tree species and species combinations.
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| 8. |
- Bolyos, Elinor, et al.
(författare)
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Treatment of process water through non-chemical methods: Removal of heavy metals and organic material
- 2001
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Rapport (populärvet., debatt m.m.)abstract
- Linköping University, in collaboration with Ribea AB, has been studying the removal of heavy metals and organic matter from process water. Specifically, the product water from a metal-polishing company in Gamleby had Zn, Cu and particulate levels that were in excess of allowable limits. The objective of the work was to develop a process for removal of these metals and the particulates without the use of chemicals and to design and install an on-site facility for larger-scale tests. Additionally, a further goal was to generalise the findings such that metals and organic matter could be removed from other process waters.
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| 9. |
- Boud, David, et al.
(författare)
-
Observing interprofessional simulation
- 2019
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Ingår i: Interprofessional Simulation in Health Care. - Cham : Springer. - 9783030195410 - 9783030195427 ; , s. 115-137
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Bokkapitel (refereegranskat)abstract
- This chapter has a particular focus on the observers’ role in simulation-based learning activities. Simulation-based learning is often organised so that participants rotates between active participation in the scenario and participation as observers. The research examples provided show that the conditions for learning are related to the locations where and the ways the observers are situated, and to how the instructions to the observers are formulated. Arguments are put forward that the observers’ role in simulation has unexploited potential for developing skills of noticing.
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| 10. |
- Cano-Cebrian, Maria-Jose, et al.
(författare)
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Chemotherapeutics Combined with Luminal Irritants : Effects on Small-Intestinal Mannitol Permeability and Villus Length in Rats
- 2022
-
Ingår i: International Journal of Molecular Sciences. - : MDPI AG. - 1661-6596 .- 1422-0067. ; 23:3
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Tidskriftsartikel (refereegranskat)abstract
- Chemotherapy causes intestinal mucositis, which includes villous atrophy and altered mucosal barrier function. However, there is an uncertainty regarding how the reduced small-intestinal surface area affects the mucosal permeability of the small marker probe mannitol (MW 188), and how the mucosa responds to luminal irritants after chemotherapy. The aims in this study were to determine (i) the relationship between chemotherapy-induced villus atrophy and the intestinal permeability of mannitol and (ii) how the mucosa regulate this permeability in response to luminal ethanol and sodium dodecyl sulfate (SDS). This was investigated by treating rats with a single intraperitoneal dose of doxorubicin, irinotecan, or 5-fluorouracil. After 72 h, jejunum was single-pass perfused and mannitol permeability determined at baseline and after 15 min luminal exposure to 15% ethanol or 5 mg/mL SDS. Tissue samples for morphological analyses were sampled from the perfused segment. All three chemotherapeutics caused a similar 30% reduction in villus length. Mannitol permeability increased with irinotecan (1.3-fold) and 5-fluorouracil (2.5-fold) and was reduced with doxorubicin (0.5-fold), suggesting that it is not epithelial surface area alone that regulates intestinal permeability to mannitol. There was no additional increase in mannitol permeability induced by luminal ethanol or SDS in the chemotherapy-treated rats compared to controls, which may be related to the relatively high basal permeability of mannitol compared to other common low-permeability probes. We therefore suggest that future studies should focus on elucidating the complex interplay between chemotherapy in combination with luminal irritants on the intestinal permeability of other probes.
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| 11. |
- Christenson, Karin, et al.
(författare)
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In vivo-transmigrated human neutrophils are resistant to antiapoptotic stimulation.
- 2011
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Ingår i: Journal of leukocyte biology. - : Oxford University Press (OUP). - 1938-3673 .- 0741-5400. ; 90:6, s. 1055-63
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Tidskriftsartikel (refereegranskat)abstract
- Neutrophils respond to microbial invasion or injury by transmigration from blood to tissue. Transmigration involves cellular activation and degranulation, resulting in altered levels of surface receptors and changed responsiveness to certain stimuli. Thus, fundamental functional changes are associated with neutrophil transmigration from blood to tissue. Neutrophils isolated from peripheral blood spontaneously enter apoptosis, a process that can be accelerated or delayed by different pro- or antiapoptotic factors. How tissue neutrophils that have transmigrated in vivo regulate cell death is poorly understood. In this study, in vivo-transmigrated neutrophils (tissue neutrophils) were collected using a skin chamber technique and compared with blood neutrophils from the same donors with respect to regulation of cell death. Skin chamber fluid contained a variety of cytokines known to activate neutrophils and regulate their lifespan. Freshly prepared tissue neutrophils had elevated activity of caspase 3/7 but were fully viable; spontaneous cell death after in vitro culture was also similar between blood and tissue neutrophils. Whereas apoptosis of cultured blood neutrophils was delayed by soluble antiapoptotic factors (e.g., TLR ligands), tissue neutrophils were completely resistant to antiapoptotic stimulation, even though receptors were present and functional. In vitro transmigration of blood neutrophils into skin chamber fluid did not fully confer resistance to antiapoptotic stimulation, indicating that a block of antiapoptotic signaling occurs specifically during in vivo transmigration. We describe a novel, functional alteration that takes place during in vivo transmigration and highlights the fact that life and death of neutrophils may be regulated differently in blood and tissue.
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| 12. |
- Chugh, Tushar, 1989, et al.
(författare)
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Method and apparatus for operating a haptic system
- 2020
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The present invention relates to a method for operating a haptic system, such as a vehicle electric steering system, etc. We present a real-time disturbance observer based control strategy for a desired steering feedback, ranging from virtual to realistic behavior. The invention covers both the impedance (or torque) and admittance (or position) control concepts.
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| 13. |
- Chugh, Tushar, 1989, et al.
(författare)
-
Model based closed-loop position control for vehicle steering systems
- 2022
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Patent (övrigt vetenskapligt/konstnärligt)abstract
- The present disclosure relates to a method for operating a haptic system (100), the haptic system (100) comprising at least one actuator (110) and at least one haptic control device (120) adapted to control the at least one actuator (110) and to provide haptic feedback to a user, the method comprising the steps of: obtaining (S1), from a feedback computational model, modelled feedback data, obtaining (S2), from a feedback estimator, estimated feedback data based on measurement data determined from measurement made on the haptic system, overlaying (S3) the modelled feedback data and the estimated feedback data to generate blended feedback data, and providing (S4) the blended feedback data to control the haptic feedback to the user.
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| 14. |
- Dahlgren, David, et al.
(författare)
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Antibody-Drug Conjugates and Targeted Treatment Strategies for Hepatocellular Carcinoma : A Drug-Delivery Perspective
- 2020
-
Ingår i: Molecules. - : MDPI AG. - 1431-5157 .- 1420-3049. ; 25:12
-
Forskningsöversikt (refereegranskat)abstract
- Increased understanding of cancer biology, pharmacology and drug delivery has provided a new framework for drug discovery and product development that relies on the unique expression of specific macromolecules (i.e., antigens) on the surface of tumour cells. This has enabled the development of anti-cancer treatments that combine the selectivity of antibodies with the efficacy of highly potent chemotherapeutic small molecules, called antibody-drug conjugates (ADCs). ADCs are composed of a cytotoxic drug covalently linked to an antibody which then selectively binds to a highly expressed antigen on a cancer cell; the conjugate is then internalized by the cell where it releases the potent cytotoxic drug and efficiently kills the tumour cell. There are, however, many challenges in the development of ADCs, mainly around optimizing the therapeutic/safety benefits. These challenges are discussed in this review; they include issues with the plasma stability and half-life of the ADC, its transport from blood into and distribution throughout the tumour compartment, cancer cell antigen expression and the ADC binding affinity to the target antigen, the cell internalization process, cleaving of the cytotoxic drug from the ADC, and the cytotoxic effect of the drug on the target cells. Finally, we present a summary of some of the experimental ADC strategies used in the treatment of hepatocellular carcinoma, from the recent literature.
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| 15. |
- Dahlgren, David
(författare)
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Biopharmaceutical aspects of intestinal drug absorption : Regional permeability and absorption-modifying excipients
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Before an orally administered drug reaches the systemic circulation, it has to dissolve in the intestinal fluids, permeate across the intestinal epithelial cell barrier, and pass through the liver. The permeation rate of drug compounds can be low and show regional differences.The thesis had two general aims. The first of these was, to determine and compare regional intestinal permeability values of model compounds in human and dog. The second was to understand the possible effects of absorption-modifying pharmaceutical excipients (AMEs) on the intestinal permeability of the model compounds. The usefulness of several preclinical animal models for predicting the impact of regional intestinal permeability and AMEs in human was also investigated.There was a good correlation between human and dog permeability values in the small intestines for the model compounds. The colon in dog was substantially more permeable than the human colon to the low permeability drug, atenolol. This difference in colonic permeability may have implications for the use of dog as a model species for prediction of human intestinal drug absorption.There were no effects of AMEs on the intestinal permeability of any of the high permeability compounds, in any animal model. In the rat single-pass intestinal perfusion model, there was a substantial increase in permeability of all low permeability drugs, induced by two AMEs, chitosan and SDS. This AME-induced increase was substantially lower in the more in vivo relevant rat and dog intraintestinal bolus models. A shorter AME exposure-time in the rat single-pass intestinal perfusion model (15 vs. 75 min) could, however, predict the result from the bolus studies in rat and dog. This illustrates the impact of intestinal transit and mucosal exposure time on AME effects in vivo. The intestinal luminal conditions and enteric neural activity also had an impact on determinations of drug permeability in the rat single-pass intestinal perfusion model, which can have implications for its in vivo relevance.In summary, this thesis used multiple in vivo models to evaluate the impact of several biopharmaceutical processes on intestinal drug absorption. This has led to an increased understanding of these absorption mechanisms.
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| 16. |
- Dahlgren, David, et al.
(författare)
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Chemotherapeutics-Induced Intestinal Mucositis : Pathophysiology and Potential Treatment Strategies
- 2021
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Ingår i: Frontiers in Pharmacology. - : Frontiers Media S.A.. - 1663-9812. ; 12
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Forskningsöversikt (refereegranskat)abstract
- The gastrointestinal tract is particularly vulnerable to off-target effects of antineoplastic drugs because intestinal epithelial cells proliferate rapidly and have a complex immunological interaction with gut microbiota. As a result, up to 40-100% of all cancer patients dosed with chemotherapeutics experience gut toxicity, called chemotherapeutics-induced intestinal mucositis (CIM). The condition is associated with histological changes and inflammation in the mucosa arising from stem-cell apoptosis and disturbed cellular renewal and maturation processes. In turn, this results in various pathologies, including ulceration, pain, nausea, diarrhea, and bacterial translocation sepsis. In addition to reducing patient quality-of-life, CIM often leads to dose-reduction and subsequent decrease of anticancer effect. Despite decades of experimental and clinical investigations CIM remains an unsolved clinical issue, and there is a strong consensus that effective strategies are needed for preventing and treating CIM. Recent progress in the understanding of the molecular and functional pathology of CIM had provided many new potential targets and opportunities for treatment. This review presents an overview of the functions and physiology of the healthy intestinal barrier followed by a summary of the pathophysiological mechanisms involved in the development of CIM. Finally, we highlight some pharmacological and microbial interventions that have shown potential. Conclusively, one must accept that to date no single treatment has substantially transformed the clinical management of CIM. We therefore believe that the best chance for success is to use combination treatments. An optimal combination treatment will likely include prophylactics (e.g., antibiotics/probiotics) and drugs that impact the acute phase (e.g., anti-oxidants, apoptosis inhibitors, and anti-inflammatory agents) as well as the recovery phase (e.g., stimulation of proliferation and adaptation).
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| 17. |
- Dahlgren, David, et al.
(författare)
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Direct In Vivo Human Intestinal Permeability (P-eff) Determined with Different Clinical Perfusion and Intubation Methods
- 2015
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Ingår i: Journal of Pharmaceutical Sciences. - : Elsevier BV. - 0022-3549 .- 1520-6017. ; 104:9, s. 2702-2726
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Forskningsöversikt (refereegranskat)abstract
- Regional in vivo human intestinal effective permeability (P-eff) is calculated by measuring the disappearance rate of substances during intestinal perfusion. P-eff is the most relevant parameter in the prediction of rate and extent of drug absorption from all parts of the intestine. Today, human intestinal perfusions are not performed on a routine basis in drug development. Therefore, it would be beneficial to increase the accuracy of the in vitro and in silico tools used to evaluate the intestinal P-eff of novel drugs. This review compiles historical P-eff data from 273 individual measurements of 80 substances from 61 studies performed in all parts of the human intestinal tract. These substances include: drugs, monosaccharaides, amino acids, dipeptides, vitamins, steroids, bile acids, ions, fatty acids, and water. The review also discusses the determination and prediction of P-eff using in vitro and in silico methods such as quantitative structure-activity relationship, Caco-2, Ussing chamber, animal intestinal perfusion, and physiologically based pharmacokinetic (PBPK) modeling. Finally, we briefly outline how to acquire accurate human intestinal P-eff data by deconvolution of plasma concentration-time profiles following regional intestinal bolus dosing.
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| 18. |
- Dahlgren, David, et al.
(författare)
-
Effect of absorption-modifying excipients, hypotonicity, and enteric neural activity in an in vivo model for small intestinal transport.
- 2018
-
Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 549:1-2, s. 239-248
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Tidskriftsartikel (refereegranskat)abstract
- The small intestine mucosal barrier is physiologically regulated by the luminal conditions, where intestinal factors, such as diet and luminal tonicity, can affect mucosal permeability. The intestinal barrier may also be affected by absorption-modifying excipients (AME) in oral drug delivery systems. Currently, there is a gap in the understanding of how AMEs interact with the physiological regulation of intestinal electrolyte transport and fluid flux, and epithelial permeability. Therefore, the objective of this single-pass perfusion study in rat was to investigate the effect of three AMEs on the intestinal mucosal permeability at different luminal tonicities (100, 170, and 290 mOsm). The effect was also evaluated following luminal administration of a nicotinic receptor antagonist, mecamylamine, and after intravenous administration of a COX-2 inhibitor, parecoxib, both of which affect the enteric neural activity involved in physiological regulation of intestinal functions. The effect was evaluated by changes in intestinal lumen-to-blood transport of six model compounds, and blood-to-lumen clearance of 51Cr-EDTA (a mucosal barrier marker). Luminal hypotonicity alone increased the intestinal epithelial transport of 51Cr-EDTA. This effect was potentiated by two AMEs (SDS and caprate) and by parecoxib, while it was reduced by mecamylamine. Consequently, the impact of enteric neural activity and luminal conditions may affect nonclinical determinations of intestinal permeability. In vivo predictions based on animal intestinal perfusion models can be improved by considering these effects. The in vivo relevance can be increased by treating rats with a COX-2 inhibitor prior to surgery. This decreases the risk of surgery-induced ileus, which may affect the physiological regulation of mucosal permeability.
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| 19. |
- Dahlgren, David, et al.
(författare)
-
Effect of paracellular permeation enhancers on intestinal permeability of two peptide drugs, enalaprilat and hexarelin, in rats
- 2021
-
Ingår i: Acta Pharmaceutica Sinica B. - : INST MATERIA MEDICA, CHINESE ACAD MEDICAL SCIENCES. - 2211-3835 .- 2211-3843. ; 11:6, s. 1667-1675
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Tidskriftsartikel (refereegranskat)abstract
- Transcellular permeation enhancers are known to increase the intestinal permeability of enalaprilat, a 349 Da peptide, but not hexarelin (887 Da). The primary aim of this paper was to investigate if paracellular permeability enhancers affected the intestinal permeation of the two peptides. This was investigated using the rat single-pass intestinal perfusion model with concomitant blood sampling. These luminal compositions included two paracellular permeation enhancers, chitosan (5 mg/mL) and ethylenediaminetetraacetate (EDTA, 1 and 5 mg/mL), as well as low luminal tonicity (100 mOsm) with or without lidocaine. Effects were evaluated by the change in lumen-to-blood permeability of hexarelin and enalaprilat, and the blood-to-lumen clearance of (51)chromium-labeled EDTA (CLCr-EDTA), a clinical marker for mucosal barrier integrity. The two paracellular permeation enhancers increased the mucosal permeability of both peptide drugs to a similar extent. The data in this study suggests that the potential for paracellular permeability enhancers to increase intestinal absorption of hydrophilic peptides with low molecular mass is greater than for those with transcellular mechanism-of-action. Further, the mucosal blood-to-lumen flux of Cr-51-EDTA was increased by the two paracellular permeation enhancers and by luminal hypotonicity. In contrast, luminal hypotonicity did not affect the lumen-to-blood transport of enalaprilat and hexarelin. This suggests that hypotonicity affects paracellular solute transport primarily in the mucosal crypt region, as this area is protected from luminal contents by a constant water flow from the crypts.
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| 20. |
- Dahlgren, David, et al.
(författare)
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Evaluation and validation of chemotherapy‐specific diarrhoea and histopathology in rats
- 2022
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : John Wiley & Sons. - 1742-7835 .- 1742-7843. ; 131:6, s. 536-546
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Tidskriftsartikel (refereegranskat)abstract
- Chemotherapy-induced mucositis is characterized by diarrhoea and villous atrophy. However, it is not well-understood why diarrhoea arises, why it only occurs with some chemotherapeutics and how it is related to villus atrophy. The objectives in this study were to determine (i) the relationship between chemotherapy-induced diarrhoea and villus atrophy and to (ii) establish and validate a rat diarrhoea model with clinically relevant endpoints. Male Wistar Han IGS rats were treated with saline, doxorubicin, idarubicin, methotrexate, 5-fluorouracil, irinotecan or 5-fluorouracil+irinotecan. After 72 h, jejunal tissue was taken for morphological, apoptotic and proliferative analyses, and faecal water content and change in body weight were determined. All treatments except methotrexate caused a similar reduction (≈42%) in villus height, but none of them altered mucosal crypt cell proliferation or apoptosis. Doxorubicin, idarubicin, irinotecan and 5-fluorouracil+irinotecan caused body weight reduction, but only irinotecan and idarubicin caused diarrhoea. No direct correlation between diarrhoea and villus height or body weight loss was observed. Therefore, studies of the mechanisms for chemotherapy-induced diarrhoea should focus on functional factors. Finally, the irinotecan and idarubicin diarrhoea models established in this study will be useful in developing supportive treatments of this common and serious adverse effect in patients undergoing chemotherapy.
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| 21. |
- Dahlgren, David, et al.
(författare)
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Evaluation of drug permeability calculation based on luminal disappearance and plasma appearance in the rat single-pass intestinal perfusion model
- 2019
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 142, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- The rat single-pass intestinal perfusion (SPIP) model is commonly used to investigate gastrointestinal physiology and membrane drug transport. The SPIP model can be used with the intestinal segment inside or outside the abdomen. The rats can also be treated with parecoxib, a selective cycloxygenase-2 inhibitor that has been shown to affect some intestinal functions following abdominal surgery, such as motility, epithelial permeability, fluid flux and ion transport. However, the impact of extra-abdominal placement of the intestinal segment in combination with parecoxib on intestinal drug transport has not been investigated. There is also uncertainty how well intestinal permeability determinations based on luminal drug disappearance and plasma appearance correlate in the rat SPIP model. The main objective of this rat in vivo study was to investigate the effect of intra- vs. extra abdominal SPIP, with and without, pretreatment with parecoxib. The effect was evaluated by determining the difference in blood-to-lumen Cr-51-EDTA clearance, lumen-to-blood permeability of a cassette-dose of four model compounds (atenolol, enalaprilat, ketoprofen, and metoprolol), and water flux. The second objective was to compare the jejunal permeability values of the model drugs when determined based on luminal disappearance or plasma appearance. The study showed that the placement of the perfused jejunal segment, or the treatment with parecoxib, had minimal effects on membrane permeability and water flux. It was also shown that intestinal permeability of low permeability compounds should be determined on the basis of data from plasma appearance rather than lumina] disappearance. If permeability is calculated on the basis of luminal disappearance, it should preferably include negative values to increase the accuracy in the determinations.
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| 22. |
- Dahlgren, David, et al.
(författare)
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Fasted and fed state human duodenal fluids : Characterization, drug solubility, and comparison to simulated fluids and with human bioavailability
- 2021
-
Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier. - 0939-6411 .- 1873-3441. ; 163, s. 240-251
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Tidskriftsartikel (refereegranskat)abstract
- Accurate in vivo predictions of intestinal absorption of low solubility drugs require knowing their solubility in physiologically relevant dissolution media. Aspirated human intestinal fluids (HIF) are the gold standard, followed by simulated intestinal HIF in the fasted and fed state (FaSSIF/FeSSIF). However, current HIF characterization data vary, and there is also some controversy regarding the accuracy of FaSSIF and FeSSIF for predicting drug solubility in HIF. This study aimed at characterizing fasted and fed state duodenal HIF from 16 human volunteers with respect to pH, buffer capacity, osmolarity, surface tension, as well as protein, phospholipid, and bile salt content. The fasted and fed state HIF samples were further used to investigate the equilibrium solubility of 17 representative low-solubility small-molecule drugs, six of which were confidential industry compounds and 11 were known and characterized regarding chemical diversity. These solubility values were then compared to reported solubility values in fasted and fed state HIF, FaSSIF and FeSSIF, as well as with their human bioavailability for both states. The HIF compositions corresponded well to previously reported values and current FaSSIF and FeSSIF compositions. The drug solubility values in HIF (both fasted and fed states) were also well in line with reported solubility data for HIF, as well as simulated FaSSIF and FeSSIF. This indicates that the in vivo conditions in the proximal small intestine are well represented by simulated intestinal fluids in both composition and drug equilibrium solubility. However, increased drug solubility in the fed vs. fasted states in HIF did not correlate with the human bioavailability changes of the same drugs following oral administration in either state.
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| 23. |
- Dahlgren, David, et al.
(författare)
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Hypotonicity-Induced Increase in Duodenal Mucosal Permeability Is Regulated by Cholinergic Receptors in Rats
- 2023
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Ingår i: Digestive Diseases and Sciences. - : Springer. - 0163-2116 .- 1573-2568. ; 68:5, s. 1815-1823
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundThe role of cholinergic receptors in the regulation of duodenal mucosal permeability in vivo is currently not fully described.AimsTo elucidate the impact of nicotinic and muscarinic acetylcholine receptor signaling in response to luminal hypotonicity (50 mM NaCl) in the proximal small intestine of rat.MethodsThe effect on duodenal blood-to-lumen clearance of 51Cr-EDTA (i.e., mucosal permeability) and motility was studied in the absence and presence of nicotinic and muscarinic receptor agonists and antagonists, a sodium channel blocker (tetrodotoxin), and after bilateral cervical vagotomy.ResultsRats with duodenal contractions responded to luminal hypotonicity by substantial increase in intestinal permeability. This response was absent in animals given a non-selective nicotinic receptor antagonist (mecamylamine) or agonist (epibatidine). Pretreatment with tetrodotoxin reduced the increase in mucosal permeability in response to luminal hypotonicity. Further, the non-selective muscarinic receptor antagonist (atropine) and agonist (bethanechol) reduced the hypotonicity-induced increase in mucosal permeability, while vagotomy was without an effect, suggesting that local enteric reflexes dominate. Finally, neither stimulating nor blocking the α7-nicotinic receptor had any significant effects on duodenal permeability in response to luminal hypotonicity, suggesting that this receptor is not involved in regulation of duodenal permeability. The effect of the different drugs on mucosal permeability was similar to the effect observed for duodenal motility.ConclusionsA complex enteric intramural excitatory neural reflex involving both nicotinic and muscarinic receptor subtypes mediates an increase in mucosal permeability induced by luminal hypotonicity.
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| 24. |
- Dahlgren, David, et al.
(författare)
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Intestinal absorption-modifying excipients : A current update on preclinical in vivo evaluations
- 2019
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 142, s. 411-420
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Tidskriftsartikel (refereegranskat)abstract
- Pharmaceutical excipients in drug products are defined as pharmacologically inactive and are integral constituents of all types of oral dosage forms. However, some excipients may increase drug absorption by interacting with the mucosal membrane. If the strategy is to use an excipient with a potential to affect the processes determining the rate and/or extent of the intestinal drug absorption, it is defined as an absorption-modifying excipients (AME). These pharmaceutical excipients may act as AMEs, depending on the amounts applied, and accordingly influence bioequivalence assessment of innovative and generic drug products, as well as enable oral delivery of peptides and oligonucleotides. This review discusses the mechanisms by which AMEs increase drug absorption, and especially permeation step. The focus is on the most recent data regarding how AMEs can be evaluated in preclinical models, with an emphasis on in situ and in vivo intestinal absorption models. The in vivo predictive value of these models is reviewed for five factors of clinical relevance for the intestinal absorption performance: (a) effect and response rate of AMEs, (b) mucosal exposure time and intestinal transit of AMEs, (c) intraluminal AME dilution and prandial state, (d) mucosa] recovery and safety, and (e) variability in the effects of the AMEs. We argue that any preclinical investigations of AMEs that fail to consider these processes will ultimately be of limited clinical value and add little to our understanding of how excipients affect intestinal drug absorption.
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| 25. |
- Dahlgren, David, et al.
(författare)
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Intestinal absorption of BCS class II drugs administered as nanoparticles : A review based on in vivo data from intestinal perfusion models
- 2020
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Ingår i: ADMET & DMPK. - : International Association of Physical Chemists (IAPC). - 1848-7718. ; 8:4, s. 375-390
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Forskningsöversikt (refereegranskat)abstract
- An established pharmaceutical strategy to increase oral drug absorption of low solubility-high permeability drugs is to create nanoparticles of them. Reducing the size of the solid-state particles increases their dissolution and transport rate across the mucus barrier and the aqueous boundary layer. Suspensions of nanoparticles also sometimes behave differently than those of larger particles in the fed state. This review compares the absorption mechanisms of nano- and larger particles in the lumen at different prandial states, with an emphasis on data derived from in vivo models. Four BSC class II drugs-aprepitant, cyclosporine, danazol and fenofibrate-are discussed in detail based on information from preclinical intestinal perfusion models.
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| 26. |
- Dahlgren, David, et al.
(författare)
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Intestinal Permeability and Drug Absorption : Predictive Experimental, Computational and In Vivo Approaches
- 2019
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 11:8
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Forskningsöversikt (refereegranskat)abstract
- The main objective of this review is to discuss recent advancements in the overall investigation and in vivo prediction of drug absorption. The intestinal permeability of an orally administered drug (given the value P-eff) has been widely used to determine the rate and extent of the drug's intestinal absorption (F-abs) in humans. Preclinical gastrointestinal (GI) absorption models are currently in demand for the pharmaceutical development of novel dosage forms and new drug products. However, there is a strong need to improve our understanding of the interplay between pharmaceutical, biopharmaceutical, biochemical, and physiological factors when predicting F-abs and bioavailability. Currently, our knowledge of GI secretion, GI motility, and regional intestinal permeability, in both healthy subjects and patients with GI diseases, is limited by the relative inaccessibility of some intestinal segments of the human GI tract. In particular, our understanding of the complex and highly dynamic physiology of the region from the mid-jejunum to the sigmoid colon could be significantly improved. One approach to the assessment of intestinal permeability is to use animal models that allow these intestinal regions to be investigated in detail and then to compare the results with those from simple human permeability models such as cell cultures. Investigation of intestinal drug permeation processes is a crucial biopharmaceutical step in the development of oral pharmaceutical products. The determination of the intestinal P-eff for a specific drug is dependent on the technique, model, and conditions applied, and is influenced by multiple interactions between the drug molecule and the biological membranes.
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| 27. |
- Dahlgren, David, et al.
(författare)
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Medicinal grade opium tincture for severe diarrhea : effect revisited in observational study
- 2024
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Ingår i: Current Opinion in Gastroenterology. - : Wolters Kluwer. - 0267-1379 .- 1531-7056. ; 40:3, s. 196-202
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Tidskriftsartikel (refereegranskat)abstract
- Purpose of review Chronic diarrhea is a common disorder that interferes with normal daily activities and results in poor quality of life. Fecal urgency and incontinence often necessitate clinical consultation, but the pathophysiological mechanisms are difficult to differentiate in a clinical setting. Therefore, drugs targeting the opioid receptors, such as diphenoxylate and loperamide, are typically used, as they reduce both gut motility and secretion.Recent findings For severe diarrhea, morphine-containing extemporaneous opium tincture drops have recently been reprofiled to a pharmaceutical. The drug is indicated for severe diarrhea in adults when other antidiarrheals do not give sufficient fecal emptying control. The pronounced effect is due to the liquid formulation with rapid onset as a drug dissolution step is avoided. A recent prospective, noninterventional study (CLARIFY) of patients treated with opioid drops demonstrates a rapid and sustained therapeutic effect. Tolerance does not develop for the antidiarrheal effect and no dependence was observed after discontinuation.Summary This mini-review discusses the use of opium derivates for treatment of diarrhea, with an emphasis on opium drops as a new medicinal grade opium for the use as additional treatment of severe diarrhea, emphasizing its mechanism of action and evaluation of the risk—benefit ratio in the clinical setting.
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| 28. |
- Dahlgren, David, et al.
(författare)
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Preclinical Effect of Absorption Modifying Excipients on Rat Intestinal Transport of Model Compounds and the Mucosal Barrier Marker 51Cr-EDTA
- 2017
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 14:12, s. 4243-4251
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Tidskriftsartikel (refereegranskat)abstract
- There is a renewed interest from the pharmaceutical field to develop oral formulations of compounds, such as peptides, oligonucleotides, and polar drugs. However, these often suffer from insufficient absorption across the intestinal mucosal barrier. One approach to circumvent this problem is the use of absorption modifying excipient(s) (AME). This study determined the absorption enhancing effect of four AMEs (sodium dodecyl sulfate, caprate, chitosan, N-acetylcysteine) on five model compounds in a rat jejunal perfusion model. The aim was to correlate the model compound absorption to the blood-to-lumen clearance of the mucosal marker for barrier integrity, 51Cr-EDTA. Sodium dodecyl sulfate and chitosan increased the absorption of the low permeation compounds but had no effect on the high permeation compound, ketoprofen. Caprate and N-acetylcysteine did not affect the absorption of any of the model compounds. The increase in absorption of the model compounds was highly correlated to an increased blood-to-lumen clearance of 51Cr-EDTA, independent of the AME. Thus, 51Cr-EDTA could be used as a general, sensitive, and validated marker molecule for absorption enhancement when developing novel formulations.
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| 29. |
- Dahlgren, David, et al.
(författare)
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Prevention of Rat Intestinal Injury with a Drug Combination of Melatonin and Misoprostol
- 2020
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 21:18
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Tidskriftsartikel (refereegranskat)abstract
- A healthy intestinal barrier prevents uptake of allergens and toxins, whereas intestinal permeability increases following chemotherapy and in many gastrointestinal and systemic diseases and disorders. Currently, there are no approved drugs that target and repair the intestinal epithelial barrier while there is a medical need for such treatment in gastrointestinal and related conditions. The objective of this single-pass intestinal perfusion study in rats was to investigate the preventive cytoprotective effect of three mucosal protective drugs-melatonin, misoprostol, and teduglutide-with different mechanisms of action on an acute jejunal injury induced by exposing the intestine for 15 min to the anionic surfactant, sodium dodecyl sulfate (SDS). The effect was evaluated by monitoring intestinal clearance of Cr-51-labeled ethylenediaminetetraacetate and intestinal histology before, during, and after luminal exposure to SDS. Our results showed that separate pharmacological pretreatments with luminal misoprostol and melatonin reduced acute SDS-induced intestinal injury by 47% and 58%, respectively, while their use in combination abolished this injury. This data supports further development of drug combinations for oral treatments of conditions and disorders related to a dysregulated or compromised mucosal epithelial barrier.
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| 30. |
- Dahlgren, David, et al.
(författare)
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Regional Intestinal Drug Permeability and Effects of Permeation Enhancers in Rat
- 2020
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 12:3
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Tidskriftsartikel (refereegranskat)abstract
- Sufficient colonic absorption is necessary for all systemically acting drugs in dosage forms that release the drug in the large intestine. Preclinically, colonic absorption is often investigated using the rat single-pass intestinal perfusion model. This model can determine intestinal permeability based on luminal drug disappearance, as well as the effect of permeation enhancers on drug permeability. However, it is uncertain how accurate the rat single-pass intestinal perfusion model predicts regional intestinal permeability and absorption in human. There is also a shortage of systematic in vivo investigations of the direct effect of permeation enhancers in the small and large intestine. In this rat single-pass intestinal perfusion study, the jejunal and colonic permeability of two low permeability drugs (atenolol and enalaprilat) and two high-permeability ones (ketoprofen and metoprolol) was determined based on plasma appearance. These values were compared to already available corresponding human data from a study conducted in our lab. The colonic effect of four permeation enhancers-sodium dodecyl sulfate, chitosan, ethylenediaminetetraacetic acid (EDTA), and caprate-on drug permeability and transport of chromium EDTA (an established clinical marker for intestinal barrier integrity) was determined. There was no difference in jejunal and colonic permeability determined from plasma appearance data of any of the four model drugs. This questions the validity of the rat single-pass intestinal perfusion model for predicting human regional intestinal permeability. It was also shown that the effect of permeation enhancers on drug permeability in the colon was similar to previously reported data from the rat jejunum, whereas the transport of chromium EDTA was significantly higher (p < 0.05) in the colon than in jejunum. Therefore, the use of permeation enhancers for increasing colonic drug permeability has greater risks than potential medical rewards, as indicated by the higher permeation of chromium EDTA compared to the drugs.
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| 31. |
- Dahlgren, David, et al.
(författare)
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Regional Intestinal Permeability in Dogs : Biopharmaceutical Aspects for Development of Oral Modified-Release Dosage Forms
- 2016
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 13:9, s. 3022-3033
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Tidskriftsartikel (refereegranskat)abstract
- The development of oral modified-release (MR) dosage forms requires an active pharmaceutical ingredient (API) with a sufficiently high absorption rate in both the small and large intestine. Dogs are commonly used in preclinical evaluation of regional intestinal absorption and in the development of novel MR dosage forms. This study determined regional intestinal effective permeability (P-eff) in dogs with the aim to improve regional Peff prediction in humans. Four model drugs, atenolol, enalaprilat, metoprolol, and ketoprofen, were intravenously and regionally dosed twice as a solution into the proximal small intestine (P-SI) and large intestine (LI) of three dogs with intestinal stomas. Based on plasma data from two separate study occasions for each dog, regional Peff values were calculated using a validated intestinal deconvolution method. The determined mean P-eff values were 0.62, 0.14, 1.06, and 3.66 X 10(-4) cm/s in the P-SI, and 0.13, 0.02, 1.03, and 2.20 X 10(-4) cm/s in the LI, for atenolol, enalaprilat, metoprolol, and ketoprofen, respectively. The determined P-SI Peff values in dog were highly correlated (R-2 = 0.98) to the historically directly determined human jejunal P-eff after a single-pass perfusion. The determined dog P-SI P-eff values were also successfully implemented in GI-Sim to predict the risk for overestimation of LI absorption of low permeability drugs. We conclude that the dog intestinal stoma model is a useful preclinical tool for determination of regional intestinal permeability. Still, further studies are recommended to evaluate additional APIs, sources of variability, and formulation types, for more accurate determination of the dog model in the drug development process.
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| 32. |
- Dahlgren, David, et al.
(författare)
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Regional Intestinal Permeability of Three Model Drugs in Human
- 2016
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Ingår i: Molecular Pharmaceutics. - : American Chemical Society (ACS). - 1543-8384 .- 1543-8392. ; 13:9, s. 3013-3021
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Tidskriftsartikel (refereegranskat)abstract
- Currently there are only a limited number of determinations of human P-eff in the distal small intestine and none in the large intestine. This has hindered the validation of preclinical models with regard to absorption in the distal parts of the intestinal tract, which can be substantial for BCS class II-IV drugs, and drugs formulated into modified-release (MR) dosage forms. To meet this demand, three model drugs (atenolol, metoprolol, and ketoprofen) were dosed in solution intravenously, and into the jejunum, ileum, and colon of 14 healthy volunteers. The P-eff of each model drug was then calculated using a validated deconvolution method. The median P-eff of atenolol in the jejunum, ileum, and colon was 0.45, 0.15, and 0.013 X 10(-4) cm/s, respectively. The corresponding values for metoprolol were 1.72, 0.72, and 1.30 X 10(-4) cm/s, and for ketoprofen 8.85, 6.53, and 3.37 X 10(-4) cm/s, respectively. This is the first study where the human Peff of model drugs has been determined in all parts of the human intestinal tract in the same subjects. The jejunal values were similar to directly determined values using intestinal single-pass perfusion, indicating that the deconvolution method is a valid approach for determining regional P-eff. The values from this study will be highly useful in the validation of preclinical regional absorption models and in silico tools.
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| 33. |
- Dahlgren, David, et al.
(författare)
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Review on the effect of chemotherapy on the intestinal barrier : Epithelial permeability, mucus and bacterial translocation
- 2023
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Ingår i: Biomedicine and Pharmacotherapy. - : Elsevier. - 0753-3322 .- 1950-6007. ; 162
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Forskningsöversikt (refereegranskat)abstract
- Chemotherapy kills fast-growing cells including gut stem cells. This affects all components of the physical and functional intestinal barrier, i.e., the mucus layer, epithelium, and immune system. This results in an altered intestinal permeability of toxic compounds (e.g., endotoxins) as well as luminal bacterial translocation into the mucosa and central circulation. However, there is uncertainty regarding the relative contributions of the different barrier components for the development of chemotherapy-induced gut toxicity. This review present an overview of the intestinal mucosal barrier determined with various types of molecular probes and methods, and how they are affected by chemotherapy based on reported rodent and human data. We conclude that there is overwhelming evidence that chemotherapy increases bacterial translocation, and that it affects the mucosal barrier by rendering the mucosa more permeable to large permeability probes. Chemotherapy also seems to impede the intestinal mucus barrier, even though this has been less clearly evaluated from a functional stand-point but certainly plays a role in bacteria translocation. Combined, it is however difficult to outline a clear temporal or succession between the different gastrointestinal events and barrier functions, especially as chemotherapy-induced neutropenia is also involved in intestinal immunological homeostasis and bacterial translocation. A thorough characterization of this would need to include a time dependent development of neutropenia, intestinal permeability, and bacterial translocation, ideally after a range of chemotherapeutics and dosing regimens.
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| 34. |
- Dahlgren, David, et al.
(författare)
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The effects of three absorption-modifying critical excipients on the in vivo intestinal absorption of six model compounds in rats and dogs.
- 2018
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Ingår i: International Journal of Pharmaceutics. - : Elsevier BV. - 0378-5173 .- 1873-3476. ; 547:1-2, s. 158-168
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Tidskriftsartikel (refereegranskat)abstract
- Pharmaceutical excipients that may affect gastrointestinal (GI) drug absorption are called critical pharmaceutical excipients, or absorption-modifying excipients (AMEs) if they act by altering the integrity of the intestinal epithelial cell membrane. Some of these excipients increase intestinal permeability, and subsequently the absorption and bioavailability of the drug. This could have implications for both the assessment of bioequivalence and the efficacy of the absorption-enhancing drug delivery system. The absorption-enhancing effects of AMEs with different mechanisms (chitosan, sodium caprate, sodium dodecyl sulfate (SDS)) have previously been evaluated in the rat single-pass intestinal perfusion (SPIP) model. However, it remains unclear whether these SPIP data are predictive in a more in vivo like model. The same excipients were in this study evaluated in rat and dog intraintestinal bolus models. SDS and chitosan did exert an absorption-enhancing effect in both bolus models, but the effect was substantially lower than those observed in the rat SPIP model. This illustrates the complexity of the AME effects, and indicates that additional GI physiological factors need to be considered in their evaluation. We therefore recommend that AME evaluations obtained in transit-independent, preclinical permeability models (e.g. Ussing, SPIP) should be verified in animal models better able to predict in vivo relevant GI effects, at multiple excipient concentrations.
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| 35. |
- Dahlgren, David, et al.
(författare)
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The In Vivo Effect of Transcellular Permeation Enhancers on the Intestinal Permeability of Two Peptide Drugs Enalaprilat and Hexarelin
- 2020
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Ingår i: Pharmaceutics. - : MDPI. - 1999-4923. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Permeation enhancers like sodium dodecyl sulfate (SDS) and caprate increase the intestinal permeability of small model peptide compounds, such as enalaprilat (349 Da). However, their effects remain to be investigated for larger low-permeability peptide drugs, such as hexarelin (887 Da). The objective of this single-pass perfusion study in rat was to investigate the effect of SDS at 5 mg/mL and of caprate administered at different luminal concentrations (5, 10, and 20 mg/mL) and pH (6.5 and 7.4). The small intestinal permeability of enalaprilat increased by 8- and 9-fold with SDS at 5 mg/mL and with caprate at 10 and 20 mg/mL but only at pH 7.4, where the free dissolved caprate concentration is higher than at pH 6.5 (5 vs. 2 mg/mL). Neither SDS nor caprate at any of the investigated luminal concentrations enhanced absorption of the larger peptide hexarelin. These results show that caprate requires doses above its saturation concentration (a reservoir suspension) to enhance absorption, most likely because dissolved caprate itself is rapidly absorbed. The absent effect on hexarelin may partly explain why the use of permeation enhancers for enabling oral peptide delivery has largely failed to evolve from in vitro evaluations into approved oral products. It is obvious that more innovative and effective drug delivery strategies are needed for this class of drugs.
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| 36. |
- Dahlgren, David, et al.
(författare)
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Time-dependent effects on small intestinal transport by absorption-modifying excipients
- 2018
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 132, s. 19-28
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Tidskriftsartikel (refereegranskat)abstract
- The relevance of the rat single-pass intestinal perfusion model for investigating in vivo time-dependent effects of absorption-modifying excipients (AMEs) is not fully established. Therefore, the dynamic effect and recovery of the intestinal mucosa was evaluated based on the lumen-to-blood flux (Jabs) of six model compounds, and the blood-to-lumen clearance of 51Cr-EDTA (CLCr), during and after 15- and 60-min mucosal exposure of the AMEs, sodium dodecyl sulfate (SDS) and chitosan, in separate experiments. The contribution of enteric neurons on the effect of SDS and chitosan was also evaluated by luminal coadministration of the nicotinic receptor antagonist, mecamylamine. The increases in Jabs and CLCr (maximum and total) during the perfusion experiments were dependent on exposure time (15 and 60 min), and the concentration of SDS, but not chitosan. The increases in Jabs and CLCr following the 15-min intestinal exposure of both SDS and chitosan were greater than those reported from an in vivo rat intraintestinal bolus model. However, the effect in the bolus model could be predicted from the increase of Jabs at the end of the 15-min exposure period, where a six-fold increase in Jabs was required for a corresponding effect in the in vivo bolus model. This illustrates that a rapid and robust effect of the AME is crucial to increase the in vivo intestinal absorption rate before the yet unabsorbed drug in lumen has been transported distally in the intestine. Further, the recovery of the intestinal mucosa was complete following 15-min exposures of SDS and chitosan, but it only recovered 50% after the 60-min intestinal exposures. Our study also showed that the luminal exposure of AMEs affected the absorptive model drug transport more than the excretion of 51Cr-EDTA, as Jabs for the drugs was more sensitive than CLCr at detecting dynamic mucosal AME effects, such as response rate and recovery. Finally, there appears to be no nicotinergic neural contribution to the absorption-enhancing effect of SDS and chitosan, as luminal administration of 0.1 mM mecamylamine had no effect.
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| 37. |
- Dahlgren, David, et al.
(författare)
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Ulcerative colitis progression : a retrospective analysis of disease burden using electronic medical records
- 2022
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Ingår i: Upsala Journal of Medical Sciences. - : Upsala Medical Society. - 0300-9734 .- 2000-1967. ; 127:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ulcerative colitis (UC) is a debilitating inflammatory bowel disease. Present knowledge regarding UC disease progression over time is limited.Objective: To assess UC progression to severe disease along with disease burden and associated factors.Methods: Electronic medical records linked with Swedish national health registries (2005-2015) were used to identify disease progression of UC. Odds of all-cause and disease-related hospitalization within 1 year were compared between patients with disease progression and those without. Annual indirect costs were calculated based on sick leave, and factors related to UC progression were examined.Results: Of the 1,361 patients with moderate UC, 24% progressed to severe disease during a median of 5.2 years. Severe UC had significantly higher odds for all-cause (OR [odds ratio] 1.47, 95% CI [confidence interval]: 1.12-1.94, P < 0.01) and UC-related hospitalization (OR 2.47, 95% CI: 1.76-3.47, P < 0.0001) compared to moderate disease. Average sick leave was higher in patients who progressed compared to those who did not (64.4 vs 38.6 days, P < 0.001), with higher indirect costs of 151,800 SEK (16,415 ) pound compared with 92,839 SEK (10,039 ) pound (P < 0.001), respectively. UC progression was related to young age (OR 1.62, 95% CI: 1.17-2.25, P < 0.01), long disease duration (OR 1.09, 95% CI: 1.03-1.15, P < 0.001), and use of corticosteroids (OR 2.49, 95% CI: 1.67-3.72, P < 0.001).Conclusion: Disease progression from moderate to severe UC is associated with more frequent and longer hospitalizations and sick leave. Patients at young age with long disease duration and more frequent gluco-corticosteroid medication are associated with progression to severe UC.
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| 38. |
- Dahlgren, Ethel, et al.
(författare)
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Att fånga folkbildning på nätet
- 2004
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Ingår i: Folkbildning och lärande med IKT-stöd : en antologi om flexibelt lärande i folkhögskolor och studieförbund. - : Fritzes offentliga publikationer, Stockholm. - 9138220733 ; , s. 73-92
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 39. |
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| 40. |
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| 41. |
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| 42. |
- Dahlgren, Liselotte, et al.
(författare)
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Differences in human papillomavirus type may influence clinical outcome in early stage cervical cancer.
- 2006
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 26:2A, s. 829-32
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The presence of human papillomavirus (HPV), the HPV type and viral load in early stage cervical carcinoma were investigated in order to elucidate whether any of these factors were important for clinical outcome. PATIENTS AND METHODS: Twelve patients who were disease-free 5 years after diagnosis were matched and compared with 12 patients who died within 2 years. The presence of HPV, HPV type and viral load in their tumours was examined by PCR. RESULTS: The distribution and load of HPV was similar in the 2 patient groups. HPV-16 was, however, significantly more common in tumours of the surviving patients than in those of patients who died (88.9% and 18.2%, respectively, p = 0.0152). CONCLUSION: HPV-16 was significantly more common in early stage carcinomas of patients surviving more than 5 years in comparison to early stage carcinomas of patients with a poor prognosis.
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| 43. |
- Dahlgren, Liselotte, et al.
(författare)
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Human papillomavirus is more common in base of tongue than in mobile tongue cancer and is a favorable prognostic factor in base of tongue cancer patients.
- 2004
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Ingår i: International Journal of Cancer. - : Wiley. - 0020-7136 .- 1097-0215. ; 112:6, s. 1015-9
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Tidskriftsartikel (refereegranskat)abstract
- The frequency of human papilloma virus (HPV) and its influence on clinical outcome was analyzed retrospectively in pre-treatment paraffin embedded biopsies from 110 patients with tongue cancer. The presence of HPV DNA was examined in 85 mobile tongue tumors and 25 base of tongue tumors by a polymerase chain reaction (PCR) with 2 general primer pairs, GP5+/6+ and CPI/IIG. When HPV-DNA was found, HPV-type specific primers and direct sequencing were used for HPV sub-type verification. Twelve of 110 (10.9%) samples were HPV-positive; 9 for HPV-16, 1 for HPV-33, 1 for HPV-35 and 1 could not be analyzed because of shortage of DNA. HPV was significantly more common in base of tongue tumors (10/25, 40.0%) compared to tumors of the mobile tongue (2/85, 2.3%). The influence of HPV on clinical outcome in mobile tongue cancer could not be studied, due to that HPV was present in too few cases. Of the 19 patients with base of tongue cancer that were included in the survival analysis, however, 7 patients with HPV-positive base of tongue cancer had a significantly favorable 5-year survival rate compared to the 12 HPV-negative patients. In conclusion, HPV is significantly more common in base of tongue cancer than in mobile tongue cancer, and has a positive impact on disease-specific survival in patients with base of tongue cancer.
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| 44. |
- Dahlstrand, Hanna, et al.
(författare)
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Presence of human papillomavirus in tonsillar cancer is a favourable prognostic factor for clinical outcome.
- 2004
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Ingår i: Anticancer Research. - 0250-7005 .- 1791-7530. ; 24:3b, s. 1829-35
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this article is to review the current knowledge on the status and significance of human papillomavirus (HPV) in tonsillar cancer. Current data in scientific reports and data from the Karolinska Hospital and Karolinska Institute, Sweden, demonstrate that approximately half of all tonsillar cancer is HPV-positive. Moreover, patients with HPV-positive cancer have a lower risk of relapse and longer survival compared to patients with HPV-negative tonsillar cancer. The favourable outcome for patients harbouring HPV-positive tonsillar cancer cannot be attributed to increased radiosensitivity, since there is no significant difference in sensitivity to radiotherapy between HPV-positive and -negative tonsillar cancer. However, HPV-positive cancer exhibits less genetic instability i.e. shows a lower degree of aneuploidy and a tendency to have fewer chromosomal aberrations, when compared to HPV-negative tonsillar cancer.
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| 45. |
- Dasgupta, Indranil, et al.
(författare)
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Validating the use of bioimpedance spectroscopy for assessment of fluid status in children.
- 2018
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Ingår i: Pediatric nephrology. - : Springer Science and Business Media LLC. - 1432-198X .- 0931-041X. ; 33:9, s. 1601-1607
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Tidskriftsartikel (refereegranskat)abstract
- Bioimpedance spectroscopy (BIS) with a whole-body model to distinguish excess fluid from major body tissue hydration can provide objective assessment of fluid status. BIS is integrated into the Body Composition Monitor (BCM) and is validated in adults, but not children. This study aimed to (1) assess agreement between BCM-measured total body water (TBW) and a gold standard technique in healthy children, (2) compare TBW_BCM with TBW from Urea Kinetic Modelling (UKM) in haemodialysis children and (3) investigate systematic deviation from zero in measured excess fluid in healthy children across paediatric age range.TBW_BCM and excess fluid was determined from standard wrist-to-ankle BCM measurement. TBW_D2O was determined from deuterium concentration decline in serial urine samples over 5days in healthy children. UKM was used to measure body water in children receiving haemodialysis. Agreement between methods was analysed using paired t test and Bland-Altman method comparison.In 61 healthy children (6-14years, 32 male), mean TBW_BCM and TBW_D2O were 21.1±5.6and 20.5±5.8L respectively. There was good agreement between TBW_BCM and TBW_D2O (R2=0.97). In six haemodialysis children (4-13years, 4 male), 45 concomitant measurements over 8months showed good TBW_BCM and TBW_UKM agreement (mean difference -0.4L, 2SD=±3.0L). In 634 healthy children (2-17years, 300 male), BCM-measured overhydration was -0.1±0.7L (10-90th percentile -0.8 to+0.6L). There was no correlation between age and OH (p=0.28).These results suggest BCM can be used in children as young as 2years to measure normally hydrated weight and assess fluid status.
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| 46. |
- Dubbelboer, Ilse R, et al.
(författare)
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Rat intestinal drug permeability : A status report and summary of repeated determinations
- 2019
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Ingår i: European journal of pharmaceutics and biopharmaceutics. - : Elsevier BV. - 0939-6411 .- 1873-3441. ; 142, s. 364-376
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal permeability is a key biopharmaceutical variable in pharmaceutical research and development, and regulatory assessment. In situ rat models are often used to predict the corresponding human intestinal permeability data. The rat single-pass intestinal perfusion (SPIP) and intestinal closed loop (ICL) models are commonly applied. The primary objective of this study was to collect, summarize, and evaluate all the available intestinal permeability data for drugs that have been obtained using these two in-situ rat models. The permeability data were also investigated for variability between the experimental designs. The literature survey found 635 permeability determinations for 90 drugs. The studies were performed on the jejunum (n = 284), whole small intestine (n = 111), colon (n = 108), ileum (n = 101), and duodenum (n = 30). All the SPIP (n = 484) and ICL (n = 147) permeability values were summarized in an easily accessible database. There was wide variability in the intestinal permeability to each drug between studies, which was unrelated to the permeability class of the drug. There was no relationship between rat intestinal permeability and luminal pH, luminal drug concentration, rat strain, experimental method, or intestinal region. There was, however, a correlation between permeability values determined in the same laboratory. This report showed that the SPIP and ICL methods are important in situ models for understanding and predicting intestinal drug absorption. However, conclusions based on permeability values sourced from different laboratories may not be reliable. Because each permeability study is unique and because between- and even within-laboratory variability can be substantial, data from individual studies should preferably be interpreted separately.
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| 47. |
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| 48. |
- Forner, Kristin, et al.
(författare)
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Optimization of the Ussing chamber setup with excised rat intestinal segments for dissolution/permeation experiments of poorly soluble drugs
- 2017
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Ingår i: Drug Development and Industrial Pharmacy. - : TAYLOR & FRANCIS LTD. - 0363-9045 .- 1520-5762. ; 43:2, s. 338-346
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Tidskriftsartikel (refereegranskat)abstract
- Context: Prediction of the in vivo absorption of poorly soluble drugs may require simultaneous dissolution/permeation experiments. In vivo predictive media have been modified for permeation experiments with Caco-2 cells, but not for excised rat intestinal segments. Objective: The present study aimed at improving the setup of dissolution/permeation experiments with excised rat intestinal segments by assessing suitable donor and receiver media. Methods: The regional compatibility of rat intestine in Ussing chambers with modified Fasted and Fed State Simulated Intestinal Fluids (Fa/FeSSIFmod) as donor media was evaluated via several parameters that reflect the viability of the excised intestinal segments. Receiver media that establish sink conditions were investigated for their foaming potential and toxicity. Dissolution/permeation experiments with the optimized conditions were then tested for two particle sizes of the BCS class II drug aprepitant. Results: Fa/FeSSIFmod were toxic for excised rat ileal sheets but not duodenal sheets, the compatibility with jejunal segments depended on the bile salt concentration. A non-foaming receiver medium containing bovine serum albumin (BSA) and Antifoam B was nontoxic. With these conditions, the permeation of nanosized aprepitant was higher than of the unmilled drug formulations. Discussion: The compatibility of Fa/FeSSIFmod depends on the excised intestinal region. The chosen conditions enable dissolution/permeation experiments with excised rat duodenal segments. The experiments correctly predicted the superior permeation of nanosized over unmilled aprepitant that is observed in vivo. Conclusion: The optimized setup uses FaSSIF(mod) as donor medium, excised rat duodenal sheets as permeation membrane and a receiver medium containing BSA and Antifoam B.
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| 49. |
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| 50. |
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