| 1. |
- Xu, Bo, 1980-, et al.
(författare)
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Elucidation of the Binding Mode of the Carboxyterminal Region of Peptide YY to the Human Y-2 Receptor
- 2018
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Ingår i: Molecular Pharmacology. - : American Society for Pharmacology & Experimental Therapeutics (ASPET). - 0026-895X .- 1521-0111. ; 93:4, s. 323-334
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the agonist-receptor interactions in the neuropeptide Y (NPY)/peptide YY (PYY) signaling system is fundamental for the design of novel modulators of appetite regulation. We report here the results of a multidisciplinary approach to elucidate the binding mode of the native peptide agonist PYY to the human Y2 receptor, based on computational modeling, peptide chemistry and in vitro pharmacological analyses. The preserved binding orientation proposed for full-length PYY and five analogs, truncated at the amino terminus, explains our pharmacological results where truncations of the N-terminal proline helix showed little effect on peptide affinity. This was followed by receptor mutagenesis to investigate the roles of several receptor positions suggested by the modeling. As a complement, PYY-(3-36) analogs were synthesized with modifications at different positions in the common PYY/NPY C-terminal fragment (32TRQRY36-amide). The results were assessed and interpreted by molecular dynamics and Free Energy Perturbation (FEP) simulations of selected mutants, providing a detailed map of the interactions of the PYY/NPY C-terminal fragment with the transmembrane cavity of the Y2 receptor. The amidated C-terminus would be stabilized by polar interactions with Gln2886.55 and Tyr2195.39, while Gln1303.32 contributes to interactions with Q34 in the peptide and T32 is close to the tip of TM7 in the receptor. This leaves the core, α-helix of the peptide exposed to make potential interactions with the extracellular loops. This model agrees with most experimental data available for the Y2 system and can be used as a basis for optimization of Y2 receptor agonists.
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| 2. |
- Jason, Johan, et al.
(författare)
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Fiber-Optic Temperature Monitoring in Pulp Production
- 2008
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Ingår i: Transactions of the IWCS. - Eatontown, NJ : International Wire & Cable Symposium. ; , s. 7-16
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Konferensbidrag (refereegranskat)abstract
- A fiber-optic temperature sensor system for monitoring of the cooking process in pulp production has been developed. The sensor system is based on intensity modulation in mechanical fiber connections caused by the temperature dependent deflection of a bimetal strip. The sensor construction includes a fiber positioning device which eliminates the poor coupling efficiency otherwise experienced with coupling based sensors. An OTDR-based control unit monitors the changes in optical power at the sensor points, and the sensor network is realized with blown fiber. The total system is thus a very cost-effective solution. In this paper the development, testing, installation and operation of the sensor system is reported on, showing the system to be suitable for cooking process temperature monitoring.
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| 3. |
- Jason, Johan, et al.
(författare)
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Fiber-Optic Temperature Monitoring in Pulp Production
- 2006
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Ingår i: Proceedings of the 55th IWCS/Focus Conference. - Eatontown, NJ : International Wire & Cable Symposium. ; , s. 41-49
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A fiber-optic temperature sensor system has been developed and implemented in the monitoring of the cooking process in pulp production. The sensor system is based on intensity modulation in mechanical multimode fiber connections caused by the temperature dependent deflection of a bimetal strip. OTDR technology is used for monitoring the changes in optical power at the sensor points in the network, and a computer system takes care of calibration curves and the power-to-temperature conversion. Fiber segments between the sensor points and the control unit are realized with blown fiber. In this paper, the development and testing of the temperature monitoring system is reported on. Sensor performance, data readout, installation issues and measurement results are discussed. The system is shown to meet the requirements on precision and response time and to be a useful tool for the monitoring of the cooking process.
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| 4. |
- Jason, Johan, et al.
(författare)
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Fibre-to-the-Sensor - Blown Fibre Technology in Fibre-Optic Sensor Networks
- 2007
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Ingår i: NOC 2007 Proceedings : 12th European Conference on Networks and Optical Communications incorporating papers of Conference on Optical Cabling and Infrastructure - OC & I. - Kista-Stockholm : Acreo. ; , s. 649-
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In this paper the use of blown fibre technology in fibre-optic sensing is discussed. Starting with a background in sensor network topologies and distributed sensor technology, realised and potential applications in industry and society are presented and discussed. The examples mentioned suggest blown fibre as an attractive approach when planning and installing a fibre-optic sensor network. Also, blown distributed fibre sensor units are proposed for use in existing microduct infrastructure.
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| 5. |
- Oskarsson, Marie E., et al.
(författare)
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In Vivo Seeding and Cross-Seeding of Localized Amyloidosis A Molecular Link between Type 2 Diabetes and Alzheimer Disease
- 2015
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Ingår i: American Journal of Pathology. - : Elsevier BV. - 0002-9440 .- 1525-2191. ; 185:3, s. 834-846
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Tidskriftsartikel (refereegranskat)abstract
- Several proteins have been identified as amyloid forming in humans, and independent of protein origin, the fibrils are morphologically similar. Therefore, there is a potential for structures with amyloid seeding ability to induce both homologous and heterologous fibril growth; thus, molecular interaction can constitute a Link between different amyloid forms. Intravenous injection with preformed fibrils from islet amyloid polypeptide (IAPP), proIAPP, or amyloid-beta (A beta) into human IAPP transgenic mice triggered IAPP amyloid formation in pancreas in 5 of 7 mice in each group, demonstrating that IAPP amyloid could be enhanced through homologous and heterologous seeding with higher efficiency for the former mechanism. Proximity Ligation assay was used for colocalization studies of IAPP and A beta in islet amyloid in type 2 diabetic patients and A beta deposits in brains of patients with Alzheimer disease. All reactivity was not detected in islet amyloid although islet beta cells express A beta PP and convertases necessary for A beta production. By contrast, IAPP and proIAPP were detected in cerebral and vascular A beta deposits, and presence of proximity Ligation signal at both locations showed that the peptides were <40 nm apart. It is not clear whether IAPP present in brain originates from pancreas or is Locally produced. Heterologous seeding between IAPP and All shown here may represent a molecular Link between type 2 diabetes and Alzheimer disease.
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| 6. |
- Paulsson, Johan F., 1976-
(författare)
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Proislet Amyloid Polypeptide (proIAPP) : Impaired Processing is an Important Factor in Early Amyloidogenesis in Type 2 Diabetes
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Amyloid is defined as extracellular protein aggregates with a characteristic fibrillar ultra-structure, Congo red affinity and a unique x-ray diffraction pattern. At present, 25 different human amyloid fibril proteins have been identified, and amyloid aggregation is associated with pathological manifestations such as Alzheimer’s disease, spongiform encephalopathy and type 2 diabetes. Amyloid aggregation triggers apoptosis by incorporation of early oligomers in cellular membranes, causing influx of ions. Amyloid is the only visible pathological islet alteration in subjects with type 2 diabetes, and islet amyloid polypeptide (IAPP) is the major islet amyloid fibril component. IAPP is produced by beta-cells and co-localized with insulin in the secretory granules. Both peptides are synthesised as pro-molecules and undergo proteolytic cleavage by the prohormone convertase 1/3 and 2. Although IAPP is the main amyloid constituent, both proIAPP and proIAPP processing intermediates have been identified in islet amyloid.The aim of this thesis was to study the role of impaired processing of human proIAPP in early islet amyloidogenesis. Five cell lines with individual processing properties were transfected with human proIAPP and expression, aggregation and viability were studied. Cells unable to process proIAPP into IAPP or to process proIAPP at the N-terminal processing site accumulated intracellular amyloid-like aggregates and underwent apoptosis. Further, proIAPP immunoreactivity was detected in intracellular amyloid-like aggregates in betacells from transgenic mice expressing human IAPP and in transplanted human beta-cells. ProIAPP was hypothesized to act as a nidus for further islet amyloid deposition, and to investigate this theory, amyloid-like fibrils produced from recombinant IAPP, proIAPP and insulin C-peptide/A-chain were injected in the tail vein of transgenic mice expressing the gene for human IAPP. Pancreata were recovered after 10 months and analysed for the presence of amyloid. Both IAPP and proIAPP fibrils but not des-31,32 proinsulin fibrils, caused an increase in affected islets and also an increase of the amyloid amount. This finding demonstrates a seeding capacity of proIAPP on IAPP fibrillogenesis. IAPP has been known for some time to trigger apoptosis in cultured cells, and a novel method for real time detection of apoptosis in beta-cells was developed. Aggregation of recombinant proIAPP and proIAPP processing intermediates were concluded to be inducers of apoptosis as potent as IAPP fibril formation.From the results of this study, a scenario for initial islet amyloidogenesis is proposed. Initial amyloid formation occurs intracellularly as a result of alterations in beta-cell processing capacity. When the host cell undergoes apoptosis intracellular proIAPP amyloid becomes extracellular and can act as seed for further islet amyloid deposition.
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| 7. |
- Paulsson, Johan F, et al.
(författare)
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Real-Time Monitoring of Apoptosis by Caspase-3-Like Protease Induced FRET Reduction Triggered by Amyloid Aggregation
- 2008
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Ingår i: Experimental Diabetes Research. - : Hindawi Limited. - 1687-5214 .- 1687-5303. ; 2008:865850
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid formation is cytotoxic and can activate the caspase cascade. Here, we monitor caspase-3-like activity as reduction of fluorescence resonance energy transfer (FRET) using the contstruct pFRET2-DEVD containing enhanced cyan fluorescent protin (EYFP) linked by the caspase-3 specific cleavage site residues DEVD. Beta-TC-6 cells were transfected, and the fluoorescence was measured at 440 nm excitation and 535 nm (EYFP) and 480 nm (ECFP) emission wavelength. Cells were incubated with recombinant pro lset Amyloid Polypeptide (rec prolAPP) or the processing metabolites of prolAPP; the N-terminal flanking peptide withIAPP (recN+IAPP); IAPP with the C-terminal flanking peptied (recIAPP+C) and lslet Amyloid Polypeptide (recIAPP). Peptides were added in solubilized from (50 mu M) or as performed amyloid-like fibrils, or as a combination of these. FRET was measured and incubation with a mixture of solubilized peptide and performed fibrils resulted in loss of FRET and apoptosis was determined to occurein cells incubated with recproIAPP (49%), recN+IAPP (46%), recIAPP (72%) and recIAPP+C (59%). These results show that proIAPP and the processing intermediates reside the same cell toxic capacity as IAPP, and they can all have a central role in the reduction of beta-cell number in type 2 diabetes.
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| 8. |
- Paulsson, Johan F, et al.
(författare)
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There is a role for proIAPP in islet amyloid fibrillogenesis
- 2008
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Islet amyloid polypeptide (IAPP) can aggregate into amyloid, a common pathological finding present extracellularly in the islets of Langerhans in individuals with type 2 diabetes. IAPP arises from posttranslational processing of the precursor proIAPP. Accumulation of proIAPP in the secretory granules can result in proIAPP-amyloid formation. We raise the following hypothesis; proIAPP can under not yet defined circumstances aggregate into amyloid-like fibrils intracellularly and at this location act as template and cross-seed amyloid formation of IAPP. We have produced recombinant peptides corresponding to proIAPP and IAPP. These peptides aggregate readily into fibrils with typical amyloid characteristics. Sonicated recproIAPP- and recIAPP- preformed fibrillar aggregates were injected intravenously to +/hIAPP/-mIAPP transgenic mice. Male mice from this strain develop islet amyloid in response to high fat diet. Control animals received an injection of preformed amyloid fibrils from the proinsulin processing intermediate (C-peptide/A-chain) or sodium chloride. All animals were fed a diet high in fat over a ten month period. The presence of islet amyloid was studied after Congo red staining. We found amyloid in 20 % of the islets in animals injected with preformed recIAPP fibrils and in 10 % of the islets in animals injected with preformed recproIAPP fibrils. Control animals developed amyloid in 1-2% of the islets. Our results support the hypothesis that proIAPP-fibrils can act as template and induce conformational changes in soluble IAPP that results in propagation of the amyloid fibrils. This is the first report on in vivo seeding of a localized amyloid form and we present data that support transport of amyloid between islets as a putative route for the spreading of islet amyloid. Our finding suggests that therapies, which use capping of fibril endings, might be useless.
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| 9. |
- Paulsson, Johan O., et al.
(författare)
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Editorial Material: Absence of the BRAF V600E mutation in pheochromocytoma in JOURNAL OF ENDOCRINOLOGICAL INVESTIGATION, vol 39, issue 6, pp 715-716
- 2016
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Ingår i: Journal of Endocrinological Investigation. - : SPRINGER. - 0391-4097 .- 1720-8386. ; 39:6, s. 715-716
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Purpose Pheochromocytomas (PCCs) are rare endocrine tumors originating from the adrenal medulla. These tumors display a highly heterogeneous mutation profile, and a substantial part of the causative genetic events remains to be explained. Recent studies have reported presence of the activating BRAF V600E mutation in PCC, suggesting a role for BRAF activation in tumor development. This study sought to further investigate the occurrence of the BRAF V600E mutation in these tumors. Methods A cohort of 110 PCCs was screened for the BRAF V600E mutation using direct Sanger sequencing. Results All cases investigated displayed wild-type sequences at nucleotide 1799 in the BRAF gene. Conclusions Taken together with all previously screened tumors up to date, only 1 BRAF V600E mutation has been found among 361 PCCs. These findings imply that the BRAF V600E mutation is a rare event in pheochromocytoma.
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| 10. |
- Paulsson, Magnus, et al.
(författare)
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Bacterial Outer Membrane Vesicles Induce Vitronectin Release Into the Bronchoalveolar Space Conferring Protection From Complement-Mediated Killing
- 2018
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Pathogens causing pneumonia utilize the complement regulator vitronectin to evade complement-mediated killing. Although vitronectin is associated with several chronic lung diseases, the role of bronchoalveolar vitronectin in pneumonia has not been studied. This study sought to reveal the involvement of vitronectin in the bronchoalveolar space during pneumonia, to assess the effect of outer membrane vesicles and endotoxin on vitronectin release, and to determine whether bacterial pathogens utilize pulmonary vitronectin for evasion. Vitronectin was analyzed in cell-free bronchoalveolar lavage fluid harvested from patients with pneumonia (n = 8) and from healthy volunteers after subsegmental endotoxin instillation (n = 13). Vitronectin binding by Pseudomonas aeruginosa and Haemophilus influenzae was analyzed, and subsequent complement evasion was assessed by serum challenge. The effects of outer membrane vesicles on vitronectin production in mouse lungs and human type II alveolar epithelial cells (A549) were determined. We detected increased vitronectin concentrations in lavage fluid during pneumonia (p = 0.0063) and after bronchial endotoxin challenge (p = 0.016). The capture of vitronectin by bacteria significantly reduced complement-mediated lysis. Following challenge with vesicles, vitronectin was detected in mouse bronchoalveolar space, and mouse alveolar epithelial cells in vivo as well as A549 cells in vitro contained increased levels of vitronectin. Taken together, outer membrane vesicles and endotoxin from Gram-negative bacteria induce vitronectin, which is released into the bronchoalveolar space, and used for evasion of complement-mediated clearance.
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| 11. |
- Sauma, Lilian, et al.
(författare)
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Peroxisome proliferator activated receptor gamma activity is low in mature primary human visceral adipocytes
- 2007
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 50:1, s. 195-201
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Tidskriftsartikel (refereegranskat)abstract
- AIMS/HYPOTHESIS: The amount of visceral fat mass strongly relates to insulin resistance in humans. The transcription factor peroxisome proliferator activated receptor gamma (PPARG) is abundant in adipocytes and regulates genes of importance for insulin sensitivity. Our objective was to study PPARG activity in human visceral and subcutaneous adipocytes and to compare this with the most common model for human disease, the mouse.MATERIALS AND METHODS: We transfected primary human adipocytes with a plasmid encoding firefly luciferase controlled by PPARG response element (PPRE) from the acyl-CoA-oxidase gene and measured PPRE activity by emission of light. RESULTS: We found that PPRE activity was 6.6-fold higher (median) in adipocytes from subcutaneous than from omental fat from the same subjects (n = 23). The activity was also 6.2-fold higher in subcutaneous than in intra-abdominal fat cells when we used a PPARG ligand-binding domain-GAL4 fusion protein as reporter, demonstrating that the difference in PPRE activity was due to different levels of activity of the PPARG receptor in the two fat depots. Stimulation with 5 micromol/l rosiglitazone did not induce a PPRE activity in visceral adipocytes that was as high as basal levels in subcutaneous adipocytes. Interestingly, in mice of two different strains the PPRE activity was similar in visceral and subcutaneous fat cells.CONCLUSIONS/INTERPRETATION: We found considerably lower PPARG activity in visceral than in subcutaneous primary human adipocytes. Further studies of the molecular mechanisms behind this difference could lead to development of drugs that target the adverse effects of visceral obesity.
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| 12. |
- Zouhar, Petr, et al.
(författare)
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UCP1-independent glucose-lowering effect of leptin in type 1 diabetes : only in conditions of hypoleptinemia
- 2020
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Ingår i: American Journal of Physiology. Endocrinology and Metabolism. - : American Physiological Society. - 0193-1849 .- 1522-1555. ; 318:1, s. E72-E86
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Tidskriftsartikel (refereegranskat)abstract
- The possibility to use leptin therapeutically for lowering glucose levels in patients with type 1 diabetes has attracted interest. However, earlier animal models of type 1 diabetes are severely catabolic with very low endogenous leptin levels, unlike most patients with diabetes. Here, we aim to test glucose-lowering effects of leptin in novel, more human-like murine models. We examined the glucose-lowering potential of leptin in diabetic models of two types: streptozotocin-treated mice and mice treated with the insulin receptor antagonist S961. To prevent hypoleptinemia, we used combinations of thermoneutral temperature and high-fat feeding. Leptin fully normalized hyperglycemia in standard chow-fed streptozotocin-treated diabetic mice. However, more humanized physiological conditions (high-fat diets or thermoneutral temperatures) that increased adiposity- and thus also leptin level-sin the diabetic mice abrogated the effects of leptin, i.e., the mice developed leptin resistance also in this respect. The glucose-lowering effect of leptin was not dependent on the presence of the uncoupling protein-1 and was not associated with alterations in plasma insulin, insulin-like growth factor 1, food intake or corticosterone but fully correlated with decreased plasma glucagon levels and gluconeogenesis. An important implication of these observations is that the therapeutic potential of leptin as an additional treatment in patients with type 1 diabetes is probably limited. This is because such patients are treated with insulin and do not display low leptin levels. Thus, the potential for a glucose-lowering effect of leptin would already have been attained with standard insulin therapy, and further effects on blood glucose level through additional leptin cannot be anticipated.
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