| 1. |
- Alvarsson, M, et al.
(författare)
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Beneficial effects of insulin versus sulphonylurea on insulin secretion and metabolic control in recently diagnosed type 2 diabetic patients
- 2003
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 26:8, s. 2231-2237
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - To evaluate whether treatment with insulin in recently diagnosed type 2 diabetes is advantageous compared with glibenclamide treatment. RESEARCH DESIGN AND METHODS - ▀-Cell function, glycemic control, and quality of life were monitored over 2 years in 39 patients with islet cell antibody-negative type 2 diabetes diagnosed 0-2 years before inclusion in a Swedish multicenter randomized clinical trial. Patients were randomized to either two daily injections of premixed 30% soluble and 70% NPH insulin or glibenclamide (3.5-10.5 mg daily). C-peptide-glucagon tests were performed yearly in duplicate after 2-3 days of temporary withdrawal of treatment. RESULTS - After 1 year the glucagon-stimulated C-peptide response was increased in the insulin-treated group by 0.14 ▒ 0.08 nmol/l, whereas it was decreased by 0.12 ▒ 0.08 nmol/l in the glibenclamide group, P < 0.02 for difference between groups. After 2 years, fasting insulin levels were higher after treatment withdrawal in the insulin-treated versus the glibenclamide-treated group (P = 0.02). HbA1c levels decreased significantly during the first year in both groups, however, at the end of the second year, HbA1c had deteriorated in the glibenclamide group (P < 0.01), but not in the insulin-treated group. The difference in evolution of HbA1c during the second year was significant between groups, P < 0.02 A questionnaire indicated no difference in well-being related to treatment. CONCLUSIONS - Early insulin versus glibenclamide treatment in type 2 diabetes temporarily prolongs endogenous insulin secretion and promotes better metabolic control.
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| 2. |
- Ankarcrona, M., et al.
(författare)
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Current and future treatment of amyloid diseases
- 2016
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Ingår i: Journal of Internal Medicine. - : Wiley. - 0954-6820 .- 1365-2796. ; 280:2, s. 177-202
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Forskningsöversikt (refereegranskat)abstract
- There are more than 30 human proteins whose aggregation appears to cause degenerative maladies referred to as amyloid diseases or amyloidoses. These disorders are named after the characteristic cross--sheet amyloid fibrils that accumulate systemically or are localized to specific organs. In most cases, current treatment is limited to symptomatic approaches and thus disease-modifying therapies are needed. Alzheimer's disease is a neurodegenerative disorder with extracellular amyloid -peptide (A) fibrils and intracellular tau neurofibrillary tangles as pathological hallmarks. Numerous clinical trials have been conducted with passive and active immunotherapy, and small molecules to inhibit A formation and aggregation or to enhance A clearance; so far such clinical trials have been unsuccessful. Novel strategies are therefore required and here we will discuss the possibility of utilizing the chaperone BRICHOS to prevent A aggregation and toxicity. Type 2 diabetes mellitus is symptomatically treated with insulin. However, the underlying pathology is linked to the aggregation and progressive accumulation of islet amyloid polypeptide as fibrils and oligomers, which are cytotoxic. Several compounds have been shown to inhibit islet amyloid aggregation and cytotoxicity in vitro. Future animal studies and clinical trials have to be conducted to determine their efficacy in vivo. The transthyretin (TTR) amyloidoses are a group of systemic degenerative diseases compromising multiple organ systems, caused by TTR aggregation. Liver transplantation decreases the generation of misfolded TTR and improves the quality of life for a subgroup of this patient population. Compounds that stabilize the natively folded, nonamyloidogenic, tetrameric conformation of TTR have been developed and the drug tafamidis is available as a promising treatment. Read more articles from the symposium: Amyloid - a multifaceted player in human health and disease.
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| 3. |
- Jurgens, Catherine A., et al.
(författare)
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beta-Cell Loss and beta-Cell Apoptosis in Human Type 2 Diabetes Are Related to Islet Amyloid Deposition
- 2011
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Ingår i: American Journal of Pathology. - : Elsevier BV. - 0002-9440 .- 1525-2191. ; 178:6, s. 2632-2640
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid deposition and reduced beta-cell mass are pathological hallmarks of the pancreatic islet in type 2 diabetes; however, whether the extent of amyloid deposition is associated with decreased beta-cell mass is debated. We investigated the possible relationship and, for the first time, determined whether increased islet amyloid and/or decreased beta-cell area quantified on histological sections is correlated with increased beta-cell apoptosis. Formalin-fixed, paraffin-embedded human pancreas sections from subjects with (n = 29) and without (n = 39) diabetes were obtained at autopsy (64 +/- 2 and 70 +/- 4 islets/subject, respectively). Amyloid and beta cells were visualized by thioflavin S and insulin inununolabeling. Apoptotic beta cells were detected by colabeling for insulin and by TUNEL. Diabetes was associated with increased amyloid deposition, decreased beta-cell area, and increased beta-cell apoptosis, as expected. There was a strong inverse correlation between beta-cell area and amyloid deposition (r = -0.42, P < 0.001). beta-Cell area was selectively reduced in individual amyloid-containing islets from diabetic subjects, compared with control subjects, but amyloid-free islets had beta-cell area equivalent to islets from control subjects. Increased amyloid 'deposition was associated with beta-cell apoptosis (r = 0.56, P < 0.01). Thus, islet amyloid is associated with decreased beta-cell area and increased beta-cell apoptosis, suggesting that islet amyloid deposition contributes to the decreased beta-cell mass that characterizes type 2 diabetes.
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| 4. |
- Kollmer, Marius, et al.
(författare)
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Electron tomography reveals the fibril structure and lipid interactions in amyloid deposits
- 2016
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 113:20, s. 5604-5609
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Tidskriftsartikel (refereegranskat)abstract
- Electron tomography is an increasingly powerful method to study the detailed architecture of macromolecular complexes or cellular structures. Applied to amyloid deposits formed in a cell culture model of systemic amyloid A amyloidosis, we could determine the structural morphology of the fibrils directly in the deposit. The deposited fibrils are arranged in different networks, and depending on the relative fibril orientation, we can distinguish between fibril meshworks, fibril bundles, and amyloid stars. These networks are frequently infiltrated by vesicular lipid inclusions that may originate from the death of the amyloid-forming cells. Our data support the role of nonfibril components for constructing fibril deposits and provide structural views of different types of lipid-fibril interactions.
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| 5. |
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| 6. |
- Lundmark, Katarzyna, et al.
(författare)
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Naturally occurring fibrillar proteins can induce AA amyloidosis by a prion-like mechanism
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Experimental AA amyloidosis, where the acute phase protein serum AA (SAA) forms amyloid fibrils, can be induced in mice provoked with inflannnatmy challenge. The time for development of amyloid is dramatically shortened when the animals concomitantly receive extract of a tissue from another mouse with amyloid 1-3. The active elusive principle has been named Amyloid Enhancing Factor (AEF) and experimental secondary amyloidosis was supposed to be a nucleation dependent process. The nature of the nucleus, however, was unknown for a long time. Our studies with synthetic amyloid-like fibrils made frmn short amyloidogenic pep tides instead of AEF 4, 5, indicate that the amyloid fibrils theruselves may act as nuclei for fibril formation (Fig. 1a). Here we present the enhanced development of AA -amyloidosis by naturally occurring amyloid-like protein fibrils.
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| 7. |
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| 8. |
- Lundmark, Katarzyna, et al.
(författare)
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Transmissibility of systemic amyloidosis by a prion-like mechanism
- 2002
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 99:10, s. 6979-6984
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Tidskriftsartikel (refereegranskat)abstract
- The generation of amyloid fibrils from an amyloidogenic polypeptide occurs by a nucleation-dependent process initiated in vitro by seeding the protein solution with preformed fibrils. This phenomenon is evidenced in vivo by the fact that amyloid protein A (AA) amyloidosis in mice is markedly accelerated when the animals are given, in addition to an inflammatory stimulus, an i.v. injection of protein extracted from AA amyloid-laden mouse tissue. Heretofore, the chemical nature of this “amyloid enhancing factor” (AEF) has not been definitively identified. Here we report that the active principle of AEF extracted from the spleen of mice with silver nitrate-induced AA amyloidosis was identified unequivocally as the AA fibril itself. Further, we demonstrated that this material was extremely potent, being active in doses <1 ng, and that it retained its biologic activity over a considerable length of time. Notably, the AEF was also effective when administered orally. Our studies have provided evidence that AA and perhaps other forms of amyloidosis are transmissible diseases, akin to the prion-associated disorders.
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| 9. |
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| 10. |
- Ma, Zhi, et al.
(författare)
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Enhanced in vitro production of amyloid-like fibrils from mutant (S20G) islet amyloid polypeptide
- 2001
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 8, s. 242-
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Tidskriftsartikel (refereegranskat)abstract
- Islet amyloid polypeptide (IAPP, “amylin”) is the amyloid-fibril-forming polypeptide in the islets of Langerhans associated with type 2 diabetes mellitus. A missense mutation in the IAPP gene associated with early-onset type 2 diabetes has been identified in the Japanese population. This mutation results in a glycine for serine substitution at position 20 of the mature IAPP molecule. Whether or not formation of islet amyloid with resulting destruction of islet tissue is the cause of this diabetes is yet not known. The present in vitro study was performed in order to investigate any influence of the amino acid substitution on the fibril formation capacity. Synthetic full-length wild type (lAPPwt) and mutant (IAPPS20G) as well as corresponding truncated peptides (position 18-29) were dissolved in dimethylsulfoxide (DMSO) or in 10% acetic acid at a concentration of 10 mg/mL and their fibril forming capacity was checked by Congo red staining, electron microscopy, a Congo red affinity assay and Thioflavine T fluorometric assay. It was found that full-length and truncated IAPPS20G both formed more amyloid-like fibrils and did this faster compared to IAPPwt. The fibril morphology differed slightly between the preparations. Conclusion: The amino acid substitution (S20G) is situated close to the region of the IAPP molecule implicated in the IAPP fibrillogenesis. The significantly increased formation of amyloid-like fibrils by IAPPS20G is highly interesting and may be associated with an increased islet amyloid formation in vivo and of fundamental importance in the pathogenesis of this specific form of diabetes.
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| 11. |
- Ma, Zhi, et al.
(författare)
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Quantitative immunohistochemical analysis of islet amyloid polypeptide (IAPP) in normal, impaired glucose tolerant, and diabetic cats
- 1998
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 5:4, s. 255-261
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Tidskriftsartikel (refereegranskat)abstract
- Islet amyloid polypeptide (IAPP, “amylin”) has been proposed as having important roles in the pathogenesis of type 2 diabetes mellitus via its biological activity and by forming islet amyloid. The domestic cat develops a type of diabetes that closely resembles type 2 diabetes in humans, including the frequent formation of islet amyloid deposits in the impaired glucose tolerant (IGT) and diabetic state. With the aid of computerized image analysis and immuno-histochemistry, we examined the IAPP and insulin content inpancreatic islets of normal, IGT and diabetic cats. IAPP immunoreactivity in beta cells from IGT cats was significantly stronger (p < 0.01) as compared with cells from normal cats, while the insulin labelling strength was unchanged. Overtly diabetic cats were usually almost devoid of beta cells. As in humans, cellular IAPP but not IAPP in islet amyloid deposits was labelled by the newly developed monoclonal antibody to IAPP 4A5, thus providing further evidence that IAPP is modified by a yet unknown mechanism during the amyloidogenic process. The study provides evidence that an increased beta cell storage of IAPP independent of insulin may be an important factor in the early phase of the development of islet amyloid in this form of diabetes.
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| 12. |
- Milardi, Danilo, et al.
(författare)
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Proteostasis of Islet Amyloid Polypeptide : A Molecular Perspective of Risk Factors and Protective Strategies for Type II Diabetes
- 2021
-
Ingår i: Chemical Reviews. - : American Chemical Society (ACS). - 0009-2665 .- 1520-6890. ; 121:3, s. 1845-1893
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Forskningsöversikt (refereegranskat)abstract
- The possible link between hIAPP accumulation and β-cell death in diabetic patients has inspired numerous studies focusing on amyloid structures and aggregation pathways of this hormone. Recent studies have reported on the importance of early oligomeric intermediates, the many roles of their interactions with lipid membrane, pH, insulin, and zinc on the mechanism of aggregation of hIAPP. The challenges posed by the transient nature of amyloid oligomers, their structural heterogeneity, and the complex nature of their interaction with lipid membranes have resulted in the development of a wide range of biophysical and chemical approaches to characterize the aggregation process. While the cellular processes and factors activating hIAPP-mediated cytotoxicity are still not clear, it has recently been suggested that its impaired turnover and cellular processing by proteasome and autophagy may contribute significantly toward toxic hIAPP accumulation and, eventually, β-cell death. Therefore, studies focusing on the restoration of hIAPP proteostasis may represent a promising arena for the design of effective therapies. In this review we discuss the current knowledge of the structures and pathology associated with hIAPP self-assembly and point out the opportunities for therapy that a detailed biochemical, biophysical, and cellular understanding of its aggregation may unveil.
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| 13. |
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| 14. |
- Nordeman, Patrik, et al.
(författare)
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C-11 and F-18 Radiolabeling of Tetra- and Pentathiophenes as PET-Ligands for Amyloid Protein Aggregates
- 2016
-
Ingår i: ACS Medicinal Chemistry Letters. - : American Chemical Society (ACS). - 1948-5875. ; 7:4, s. 368-373
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Tidskriftsartikel (refereegranskat)abstract
- Three oligothiophenes were evaluated as PET ligands for the study of local and systemic amyloidosis ex vivo using tissue from patients with amyloid deposits and in vivo using healthy animals and PET-CT. The ex vivo binding studies revealed that all three labeled compounds bound specifically to human amyloid deposits. Specific binding was found in the heart, kidney, liver, and spleen. To verify the specificity of the oligothiophenes toward amyloid deposits, tissue sections with amyloid pathology were stained using the fluorescence exhibited by the compounds and evaluated with multiphoton microscopy. Furthermore, a in vivo monkey PET-CT study showed very low uptake in the brain, pancreas, and heart of the healthy animal indicating low nonspecific binding to healthy tissue. The biological evaluations indicated that this is a promising group of compounds for the visualization of systemic and localized amyloidosis.
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| 15. |
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| 16. |
- 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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| 17. |
- Sjölander, Daniel, et al.
(författare)
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Establishing the fluorescent amyloid ligand h-FTAA for studying human tissues with systemic and localized amyloid
- 2016
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 23:2, s. 98-108
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Tidskriftsartikel (refereegranskat)abstract
- Rapid and accurate detection of amyloid deposits in routine surgical pathology settings are of great importance. The use of fluorescence microscopy in combination with appropriate amyloid specific dyes is very promising in this regard. Here we report that a luminescent conjugated oligothiophene, h-FTAA, rapidly and with high sensitivity and selectivity detects amyloid deposits in verified clinical samples from systemic amyloidosis patients with AA, AL and ATTR types; as well as in tissues laden with localized amyloidosis of AANF, AIAPP and ASem1 type. The probe h-FTAA emitted yellow red fluorescence on binding to amyloid deposits, whereas no apparent staining was observed in surrounding tissue. The only functional structure stained with h-FTAA showing the amyloidotypic fluorescence spectrum was Paneth cell granules in intestine. Screening of 114 amyloid containing tissues derived from 107 verified (Congo red birefringence and/or immunohistochemistry) amyloidosis patients revealed complete correlation between h-FTAA and Congo red fluorescence (107/107, 100% sensitivity). The majority of Congo red negative control cases (27 of 32, 85% specificity) were negative with h-FTAA. Small Congo red negative aggregates in kidney, liver, pancreas and duodenum were found by h-FTAA fluorescence in five control patients aged 72-83 years suffering from diverse diseases. The clinical significance of these false-positive lesions is currently not known. Because h-FTAA fluorescence is one magnitude brighter than Congo red and as the staining is performed four magnitudes lower than the concentration of dye, we believe that these inclusions are beyond detection by Congo red. We conclude that h-FTAA is a fluorescent hypersensitive, rapid and powerful tool for identifying amyloid deposits in tissue sections. Use of h-FTAA can be exploited as a rapid complementary technique for accurate detection of amyloid in routine surgical pathology settings. Our results also implicate the potential of the technique for detection of prodromal amyloidosis as well as for discovery of new amyloid-like protein aggregates in humans.
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| 18. |
- Sjölander, Daniel, et al.
(författare)
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Evaluation of the fluorescent amyloid ligand h-FTAA in human tissues with systemic and localized amyloid
- 2014
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Rapid and accurate detection of amyloid deposits in routine surgical pathology settings are of great importance. The use of fluorescence microscopy in combination with appropriate amyloid specific dyes is very promising in this regard. Most systemic amyloidosis are progressive and lethal. Disease specific therapy depends on the identification of the offending proteins. Here we report that a luminescent conjugated oligothiophene, h-FTAA, rapidly and with high sensitivity and selectivity detects amyloid deposits in verified clinical samples from systemic amyloidosis patients with AA, AL, and ATTR types; as well as in tissues laden with localized amyloidosis of AANF, AIAPP and ASem1 type. The probe h-FTAA emitted yellow red fluorescence on binding to amyloid deposits, whereas no apparent staining was observed in surrounding tissue. Screening of 114 amyloid containing tissues derived from §07 verified (Congo red birefringence and immunohistochemistry) amyloidosis patients revealed complete correlation between h-FTAA and Congo red fluorescence. We conclude that h-FTAA is a fluorescent hypersensitive, rapid and powerful tool for identifying amyloid deposits in tissue sections. H-FTAA staining can be utilized as a rapid complementary technique for accurate detection of amyloid in routine surgical pathology settings. It was also revealed that within 5 of 15 age matched Congo red negative control samples h-FTAA detects microdeposits of amyloid-like protein aggregates in liver and kidney. The results emphasize the potential of the dye for detection of prodromal amyloidosis as well as for discovery of novel amyloid-like protein aggregates in humans.
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| 19. |
- Solomon, Alan, et al.
(författare)
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Amyloidogenic potential of foie gras
- 2007
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 104:26, s. 10998-11001
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Tidskriftsartikel (refereegranskat)abstract
- The human cerebral and systemic amyloidoses and prion-associated spongiform encephalopathies are acquired or inherited protein folding disorders in which normally soluble proteins or peptides are converted into fibrillar aggregates. This is a nucleation-dependent process that can be initiated or accelerated by fibril seeds formed from homologous or heterologous amyloidogenic precursors that serve as an amyloid enhancing factor (AEF) and has pathogenic significance in that disease may be transmitted by oral ingestion or parenteral administration of these conformationally altered components. Except for infected brain tissue, specific dietary sources of AEF have not been identified. Here we report that commercially available duck- or goose-derived foie gras contains birefringent congophilic fibrillar material composed of serum amyloid A-related protein that acted as a potent AEF in a transgenic murine model of secondary (amyloid A protein) amyloidosis. When such mice were injected with or fed amyloid extracted from foie gras, the animals developed extensive systemic pathological deposits. These experimental data provide evidence that an amyloid-containing food product hastened the development of amyloid protein A amyloidosis in a susceptible population. On this basis, we posit that this and perhaps other forms of amyloidosis may be transmissible, akin to the infectious nature of prion-related illnesses.
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| 20. |
- Thelander, Ulrika, et al.
(författare)
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Cardiac microcalcifications in transthyretin (ATTR) amyloidosis.
- 2022
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 352, s. 84-91
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Bone tracers bind to amyloid-containing heart of most patients with ATTR amyloidosis. Amyloid deposits outside the heart are often scarce and bone scintigraphy is increasingly often used to diagnose cardiac involvement. However, the nature of the binding of bone tracers to the heart is not clear.OBJECTIVE: To identify possible calcium deposits in hearts with amyloid, explaining bone tracer binding.METHODS AND RESULTS: Formalin-fixed and paraffin embedded cardiac specimens from three patients with ATTR and one with AL amyloidosis, all with cardiac deposits, were studied. The specimens covered large parts of the heart. Sections were stained immunohistochemically for ATTR deposits and according to von Kóssa for calcifications. The study identified in all hearts, but particularly in the ATTR materials, focal, tight swarms of tiny calcifications. These were sometimes associated with amyloid but found as frequent in areas without such deposits. Autoradiography with [99mTc]Tc labelled 3,3-disphos-phono-1,2-propanodicarboxylic acid (DPD) revealed labelling in von Kóssa positive areas. Electron microscopically the particles were not amorphous but had a complex structured appearance and were often surrounded by a membrane, indicating a cellular origin. Labelling with antibodies against ubiquitin and P62 pointed to result from autophagy.CONCLUSIONS: Our study indicates that binding of skeletal probes to amyloid-containing hearts depends on an irregular presence of clouds of very tiny calcifications, which seem not to be directly associated with amyloid fibrils. Therefore, [99mTc]Tc-DPD bone scans can be considered surrogate markers of ATTR amyloid but have to be used carefully to estimate amyloid amount or disease progression.
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| 21. |
- Westermark, Gunilla T., et al.
(författare)
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AA Amyloidosis : Pathogenesis and Targeted Therapy
- 2015
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Ingår i: Annual Review Of Pathology. - : ANNUAL REVIEWS. - 9780824343101 ; , s. 321-344
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Bokkapitel (refereegranskat)abstract
- The understanding of why and how proteins misfold and aggregate into amyloid fibrils has increased considerably during recent years. Central to amyloid formation is an increase in the frequency of the beta-sheet structure, leading to hydrogen bonding between misfolded monomers and creating a fibril that is comparably resistant to degradation. Generation of amyloid fibrils is nucleation dependent, and once formed, fibrils recruit and catalyze the conversion of native molecules. In AA amyloidosis, the expression of cytokines, particularly interleukin 6, leads to overproduction of serum amyloid A (SAA) by the liver. A chronically high plasma concentration of SAA results in the aggregation of amyloid into cross-beta-sheet fibrillar deposits by mechanisms not fully understood. Therefore, AA amyloidosis can be thought of as a consequence of long-standing inflammatory disease. This review summarizes current knowledge about AA amyloidosis. The systemic amyloidoses have been regarded as intractable conditions, but improvements in the understanding of fibril composition and pathogenesis over the past decade have led to the development of a number of different therapeutic approaches with promising results.
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| 22. |
- Westermark, Gunilla T., et al.
(författare)
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AA-amyloidosis. Tissue component-specific association of various protein AA subspecies and evidence of a fourth SAA gene product
- 1990
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Ingår i: American Journal of Pathology. - 0002-9440. ; 137:2, s. 377-383
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Tidskriftsartikel (refereegranskat)abstract
- Protein AA, the major repetitive protein subunit present in fibrils deposited in AA-amyloidosis, is an N-terminal cleavage product of a 104-amino acid precursor, serum amyloid A (SAA). Protein AA subspecies varying between 45 and 94 amino acids in length have been described. In this study it is shown that the different protein AA subspecies are not evenly distributed in amyloid deposits and that in single patients, certain subspecies of protein AA are deposited in specific tissue component sites. Thus larger protein AA subspecies occur in lower concentration in amyloid in the glomeruli compared to other sites and are especially found in amyloid in vessel walls. Three different SAA forms have been predicted from genomic and complementary DNA studies. The existence of a fourth type has been suspected from amino acid sequence studies of purified SAA. Protein AA derived from this fourth type of SAA is now shown to be present in amyloid fibrils in one of the patients studied in this paper.
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| 23. |
- Westermark, Gunilla T, et al.
(författare)
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Alkali-degradation of amyloid : an ancient method useful for making monoclonal antibodies against amyloid fibril proteins
- 2009
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 0300-9475 .- 1365-3083. ; 70:6, s. 535-540
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Tidskriftsartikel (refereegranskat)abstract
- The systemic amyloidoses constitute a group of life-threatening disorders at which one out of about 15 different proteins have polymerized into fibrils. Prognosis and treatment varies widely and depends on the biochemical type. Determination of this has usually to be performed by immunohistochemistry which is a challenge because of lack of monospecific antibodies that can be used on formaldehyde-fixed tissue sections. We have here used an old method to create immunogenic fragments of AL-amyloid fibrils by partial degradation and solubilization with sodium hydroxide. The mouse monoclonal antibody pwlam raised against this material, labelled AL-amyloid deposits of lambda origin strongly and specifically in sections of formaldehyde-fixed and paraffin-embedded tissues.
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| 24. |
- Westermark, Gunilla T., et al.
(författare)
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Amyloid and Transplanted Islets Reply
- 2008
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Ingår i: New England Journal of Medicine. - 0028-4793 .- 1533-4406. ; 359:25, s. 2729-2731
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Tidskriftsartikel (refereegranskat)
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| 25. |
- Westermark, Gunilla T, et al.
(författare)
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Development of Mouse Monoclonal Antibodies Against Human Amyloid Fibril Proteins for Diagnostic and Research Purposes
- 2018
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Ingår i: Methods in Molecular Biology. - New York, NY : Springer New York. - 1064-3745 .- 1940-6029. ; 1779, s. 401-414
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Tidskriftsartikel (refereegranskat)abstract
- Commercial antibodies against varying proteins are often not optimal for identification of proteins in their amyloid fibril forms. Reasons can be the different conformation but also a variety of modifications like N- or C-terminal truncation. Therefore, development of own monoclonal antibodies against amyloid fibril proteins may be advantageous. This chapter gives suggestions of how to be successful in such approaches.
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| 26. |
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| 27. |
- Westermark, Gunilla T., et al.
(författare)
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Further Evidence for Amyloid Deposition in Clinical Pancreatic Islet Grafts
- 2012
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 93:2, s. 219-223
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The reasons for the long-term complete or partial loss of islet graft function are unknown, but there are obviously other reasons than just pure allogeneic graft rejection. Earlier studies have shown that deposition of islet amyloid polypeptide amyloid in transplanted islets may indicate a mechanism for loss of β cells. MATERIALS AND METHODS: Sections from liver material from four deceased islet-bearing recipients have been scrutinized for the presence of amyloid. Clinical data and certain aspects of the islet graft pathology of these patients have been published previously. RESULT: With this extended histological analysis, we demonstrate the occurrence of amyloid deposits in islets transplanted into the liver in three of four patients with type 1 diabetes. CONCLUSION: The finding adds evidence to the assumption that aggregation of islet amyloid polypeptide might be an important cause of progressing β-cell dysfunction in clinically transplanted islets.
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| 28. |
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| 29. |
- Westermark, Gunilla T., et al.
(författare)
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Islet Amyloid Polypeptide and Diabetes
- 2013
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Ingår i: Current protein and peptide science. - : Bentham Science Publishers Ltd.. - 1389-2037 .- 1875-5550. ; 14:4, s. 330-337
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Forskningsöversikt (refereegranskat)abstract
- Islet amyloid polypeptide (IAPP, amylin) is a 37 amino acid residue hormone expressed mainly by pancreatic islet beta cells and to less extent by some gastrointestinal endocrine cells and by certain regions in central nervous system. In experimental systems a number of different effects have been ascribed to IAPP but the in vivo importance of many of them is still unknown. At least effects on the central nervous system and on endocrine pancreatic cells are likely to be physiologically relevant. In these tissues calcitonin receptors and receptor activity-modifying proteins (RAMPs) 1 and 3, creating high affinity IAPP receptors have been identified. How expression of the components of these complexes are regulated and how further signaling is conducted are more or less unknown. IAPP is most well-known for its ability to aggregate into amyloid fibrils in islets of Langerhans in association with type 2 diabetes leading to loss of beta cells. In addition, amyloid is deposited between endocrine cells and between such cells and capillaries and most likely disturbs important interactions between the cells. How IAPP receptor complexes are affected by the amyloid formation process or by amyloid itself, or vice versa, are completely unknown.
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| 30. |
- Westermark, Gunilla T., et al.
(författare)
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Localized amyloids important in diseases outside the brain : lessons from the islets of Langerhans and the thoracic aorta
- 2011
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Ingår i: The FEBS Journal. - : Wiley. - 1742-464X .- 1742-4658. ; 278:20, s. 3918-3929
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Forskningsöversikt (refereegranskat)abstract
- It has long been understood that amyloids can be lethal in systemic diseases. More recently, it has been accepted that local cerebral aggregation of the small peptide A beta is involved in the pathogenesis of Alzheimer's disease. Protein aggregation, with the generation of small amyloid deposits in specific organs, also occurs outside the central nervous system and often is associated with increased cell death. In this review, we discuss two lesser known but common localized amyloid fibril-forming proteins: the polypeptide hormone islet amyloid polypeptide (IAPP) and the lactadherin-derived peptide medin. IAPP aggregates and induces the depletion of islet beta-cells in type 2 diabetes and in islets transplanted into type 1 diabetic subjects. Initial amyloid deposition occurs intracellularly and parts of this amyloid consist of proIAPP. Medin derived from lactadherin expressed by smooth muscle cells aggregates into amyloid in certain arteries, particularly the thoracic aortic media layer, and may have a role in the generation of the potentially lethal conditions of thoracic aortic aneurysm and dissection.
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| 31. |
- Westermark, Gunilla T., et al.
(författare)
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Prion-like aggregates : infectious agents in human disease
- 2010
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Ingår i: Trends in Molecular Medicine. - : Elsevier BV. - 1471-4914 .- 1471-499X. ; 16:11, s. 501-507
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Forskningsöversikt (refereegranskat)abstract
- According to the 'protein only hypothesis', Creutzfeldt- Jakob disease and other prion disorders are transmissible by misfolded and aggregaled prion proteins that act as templates for the misfolding of the same protein in the recipient. The misfolding and aggregation of the prion protein are akin to the genesis of amyloid fibrils formed by several human and animal proteins associated with more common diseases. Two murine forms of amyloidosis, including a model of human AA amyloidosis, are transmissible. Here, we explore the possibility that human prion diseases and more common maladies associated with amyloid deposits might be transmissible by seeding or perhaps even by crossing species barriers.
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| 32. |
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| 33. |
- Westermark, Gunilla T., et al.
(författare)
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Serum amyloid A and protein AA : molecular mechanisms of a transmissible amyloidosis
- 2009
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Ingår i: FEBS Letters. - : Wiley. - 0014-5793 .- 1873-3468. ; 583:16, s. 2685-2690
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Forskningsöversikt (refereegranskat)abstract
- Systemic AA-amyloidosis is a complication of chronic inflammatory diseases and the fibril protein AA derives from the acute phase reactant serum AA. AA-amyloidosis can be induced in mice by an inflammatory challenge. The lag phase before amyloid develops can be dramatically shortened by administration of a small amount of amyloid fibrils. Systemic AA-amyloidosis is transmissible in mice and may be so in humans. Since transmission can cross species barriers it is possible that AA-amyloidosis can be induced by amyloid in food, e.g. foie gras. In mice, development of AA-amyloidosis can also be accelerated by other components with amyloid-like properties. A new possible risk factor may appear with synthetically made fibrils from short peptides, constructed for tissue repair.
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| 34. |
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| 35. |
- Westermark, Per, et al.
(författare)
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Islet amyloid polypeptide, islet amyloid, and diabetes mellitus
- 2011
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Ingår i: Physiological Reviews. - : American Physiological Society. - 0031-9333 .- 1522-1210. ; 91:3, s. 795-826
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Forskningsöversikt (refereegranskat)abstract
- Islet amyloid polypeptide (IAPP, or amylin) is one of the major secretory products of beta-cells of the pancreatic islets of Langerhans. It is a regulatory peptide with putative function both locally in the islets, where it inhibits insulin and glucagon secretion, and at distant targets. It has binding sites in the brain, possibly contributing also to satiety regulation and inhibits gastric emptying. Effects on several other organs have also been described. IAPP was discovered through its ability to aggregate into pancreatic islet amyloid deposits, which are seen particularly in association with type 2 diabetes in humans and with diabetes in a few other mammalian species, especially monkeys and cats. Aggregated IAPP has cytotoxic properties and is believed to be of critical importance for the loss of beta-cells in type 2 diabetes and also in pancreatic islets transplanted into individuals with type 1 diabetes. This review deals both with physiological aspects of IAPP and with the pathophysiological role of aggregated forms of IAPP, including mechanisms whereby human IAPP forms toxic aggregates and amyloid fibrils.
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| 36. |
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| 37. |
- Westermark, Per, et al.
(författare)
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Transthyretin-derived amyloidosis : Probably a common cause of lumbar spinal stenosis
- 2014
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 119:3, s. 223-228
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Tidskriftsartikel (refereegranskat)abstract
- Background.Senile systemic amyloidosis (SSA) derived from wild-type transthyretin is a fairly common condition of old individuals, particularly men. The main presentation is by cardiac involvement, which can lead to severe restrictive cardiomyopathy. SSA is, however, a systemic disease, and amyloid deposits may appear in many other tissues but are thought to be without clinical symptoms outside the heart. Amyloid is a very common finding in cartilage and ligaments of elderly subjects, and transthyretin has been demonstrated in some deposits. Lumbar spinal stenosis is also a condition of usually elderly individuals in whom narrowing of the lumbar spinal canal leads to compression of nerves to the lower limbs.Results. We questioned whether lumbar spinal stenosis sometimes could be a manifestation of undiagnosed SSA. In this first report we have studied the presence of amyloid in material obtained at surgery for spinal stenosis in 26 patients. Amyloid was found in 25 subjects. Transthyretin was demonstrated immunohistochemically in 5 out of 15 studied resected tissues. Four of the positive materials were analyzed with Western blot revealing both full-length transthyretin (TTR) and C-terminal TTR fragments, typically seen in SSA.Conclusion. We conclude that lumbar spinal stenosis quite frequently may be a consequence of SSA and that further studies are warranted.
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| 38. |
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| 39. |
- Caballero, Francisco, et al.
(författare)
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Birth and Death of Human beta-Cells in Pancreases From Cadaver Donors, Autopsies, Surgical Specimens, and Islets Transplanted Into Mice
- 2014
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Ingår i: Cell Transplantation. - 0963-6897 .- 1555-3892. ; 23:2, s. 139-151
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Tidskriftsartikel (refereegranskat)abstract
- There is great interest in the potential of the human endocrine pancreas for regeneration by beta-cell replication or neogenesis. Our aim was to explore this potential in adult human pancreases and in both islet and exocrine tissue transplanted into mice. The design was to examine pancreases obtained from cadaver donors, autopsies, and fresh surgical specimens and compare these findings with those obtained from islet and duct tissue grafted into the kidney. Islets and exocrine tissue were transplanted into normoglycemic ICR-SCID mice and studied 4 and 14 weeks later. beta-Cell replication, as assessed by double staining for insulin and Ki67, was 0.22 +/- 0.03% at 4 weeks and 0.13 +/- 0.03% at 14 weeks. In contrast, no evidence of beta-cell replication could be found in 11 cadaver donor and 10 autopsy pancreases. However, Ki67 staining of beta-cells in frozen sections obtained at surgery was comparable to that found in transplanted islets. Evidence for neogenesis in transplanted pancreatic exocrine tissue was supported by finding beta-cells within the duct epithelium and the presence of cells double stained for insulin and cytokeratin 19 (CK19). However, beta-cells within the ducts never constituted more than 1% of the CK19-positive cells. With confocal microscopy, 7 of 12 examined cells expressed both markers, consistent with a neogeneic process. Mice with grafts containing islet or exocrine tissue were treated with various combinations of exendin-4, gastrin, and epidermal growth factor; none increased beta-cell replication or stimulated neogenesis. In summary, human beta-cells replicate at a low level in islets transplanted into mice and in surgical pancreatic frozen sections, but rarely in cadaver donor or autopsy pancreases. The absence of beta-cell replication in many adult cadaver or autopsy pancreases could, in part, be an artifact of the postmortem state. Thus, it appears that adult human beta-cells maintain a low level of turnover through replication and neogenesis.
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| 40. |
- Carlsson, Per-Ola, et al.
(författare)
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Transplantation of macroencapsulated human islets within the bioartificial pancreas βAir to patients with type 1 diabetes mellitus
- 2018
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Ingår i: American Journal of Transplantation. - : Elsevier BV. - 1600-6135 .- 1600-6143. ; 18:7, s. 1735-1744
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Tidskriftsartikel (refereegranskat)abstract
- Macroencapsulation devices provide the dual possibility to immunoprotect transplanted cells while also being retrievable; the latter bearing importance for safety in future trials with stem-cell derived cells. However, macroencapsulation entails a problem with oxygen supply to the encapsulated cells. The βAir device solves this with an incorporated refillable oxygen tank. This phase 1 study evaluated the safety and efficacy of implanting the βAir device containing allogeneic human pancreatic islets to patients with type 1 diabetes. Four patients were transplanted with 1-2 βAir devices, each containing 155000-180000 IEQ (i.e. 1800-4600 IEQ per kg body weight), and monitored for 3-6 months, followed by the recovery of devices. Implantation of the βAir device was safe and successfully prevented immunization and rejection of the transplanted tissue. However, although beta cells survived in the device, only minute levels of circulating C-peptide were observed with no impact on metabolic control. Fibrotic tissue with immune cells was formed in capsule surroundings. Recovered devices displayed a blunted glucose-stimulated insulin response, and amyloid formation in the endocrine tissue. We conclude that the βAir device is safe and can support survival of allogeneic islets for several months, although the function of the transplanted cells was limited.
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| 41. |
- Dahlqvist, Johanna, 1979-, et al.
(författare)
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Ichthyin/NIPAL4 localizes to keratins and desmosomes in epidermis and Ichthyin mutations affect epidermal lipid metabolism
- 2012
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Ingår i: Archives of Dermatological Research. - : Springer Science and Business Media LLC. - 0340-3696 .- 1432-069X. ; 304:5, s. 377-386
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Tidskriftsartikel (refereegranskat)abstract
- Autosomal recessive congenital ichthyosis (ARCI) is a group of disorders characterized by abnormal desquamation of the skin and a disrupted epidermal water barrier. Ichthyin/NIPAL4 gene mutations have been identified in a subgroup of ARCI patients, but the role of ichthyin in epidermis remains elusive. In order to obtain new insights concerning the characteristics of ichthyin and the ARCI pathogenesis, we studied the expression and localization of ichthyin and related epidermal components in cultured keratinocytes and skin sections from patients with Ichthyin mutations and healthy controls. We observed an up-regulation of Ichthyin mRNA levels after in vitro differentiation of keratinocytes from both a patient with Ichthyin mutations and controls. Confocal and electron microscopy analyses of immunolabeled skin sections revealed that ichthyin localizes to desmosomes and keratins in both patients with mutant Ichthyin and controls, with an increased immunolabeling in patients. Nile red lipid analysis of skin sections exposed intra-cellular lipid accumulations in cells of the granular and cornified layers in patients but not in controls, consistent with the pathognomonic lipid membrane structures previously identified in epidermis from patients. Our combined findings indicate that ichthyin is associated with keratins and desmosomes in epidermis and is involved in lipid metabolism, possibly through processing of lamellar bodies. These results provide new clues to the understanding of the epidermal water barrier and the pathogenesis in ARCI.
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| 42. |
- Donadio, Vincenzo, et al.
(författare)
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Phosphorylated α-synuclein in skin Schwann cells : a new biomarker for multiple system atrophy
- 2023
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Ingår i: Brain. - : Oxford University Press. - 0006-8950 .- 1460-2156. ; 146:3, s. 1065-1074
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Tidskriftsartikel (refereegranskat)abstract
- Multiple system atrophy (MSA) is characterized by accumulation of phosphorylated α-synuclein (p-syn) as glial cytoplasmic inclusions in the brain and a specific biomarker for this disorder is urgently needed. We aimed at investigating if p-syn can also be detected in skin Remak non-myelinating Schwann cells (RSCs) as Schwann cell cytoplasmic inclusions (SCCi) and may represent a reliable clinical biomarker for MSA.This cross-sectional diagnostic study evaluated skin p-syn in 96 patients: 46 with probable MSA (29 with parkinsonism type MSA and 17 with cerebellar type MSA), 34 with Parkinson's disease (PD) and 16 with dementia with Lewy bodies (DLB). We also included 50 healthy control subjects. Patients were recruited from five different medical centres. P-syn aggregates in skin sections were stained by immunofluorescence, followed by analyses with confocal microscopy and immuno-electron microscopy. All analyses were performed in a blinded fashion.Overall, p-syn aggregates were found in 78% of MSA patients and 100% of patients with PD/DLB, whereas they could not be detected in controls. As for neuronal aggregates 78% of MSA patients were positive for p-syn in somatic neurons, whereas all PD/DLB patients were positive in autonomic neurons. When analysing the presence of p-syn in RSCs, 74% of MSA patients were positive, whereas no such SCCi could be observed in PD/DLB patients. Analyses by immuno-electron microscopy confirmed that SCCi were only found in cases with MSA and thus absent in those with PD/DLB.In conclusion, our findings demonstrate that (i) fibrillar p-syn in RSCs is a pathological hallmark of MSA and may be used as a specific and sensitive disease biomarker; (ii) in Lewy body synucleinopathies (PD/DLB) only neurons contain p-syn deposits; and (iii) the cell-specific deposition of p-syn in the skin thus mirrors that of the brain in many aspects and suggests that non-myelinated glial cells are also involved in the MSA pathogenesis.
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| 43. |
- Gu, Xiaohong, et al.
(författare)
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Proteotoxicity and Phenotypic Variability of ATTR Amyloidosis in Drosophila Melanogaster Model
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Systemic amyloidosis is a rare condition in which amyloid deposits are seen in multiple organ systems. The most prevalent systemic amyloidosis is caused by deposits of wild type transthyretin, and when advanced deposits occur in the heart, the patient develops restrictive cardiomyopathy (TTR-CM). More than 120 mutations have been reported in the ttr gene. Some mutations have been associated with hereditary transthyretin amyloidosis, whereas others have been shown to prevent misfolding of the TTR protein. The clinical profile in hereditary ATTR amyloidosis differs in terms of onset of age, tissue distribution, symptoms, disease penetrance, and prognosis.The Gal4-UAS system was used to produce flies expressing human wildtype TTR (TTRwt) and TTR with single mutations (TTRV30L, TTRV30M, TTRL55P, TTRR104H, TTRA109S, TTRA109T, TTRL111M, and TTRT119M). The white eye fly (w-) crossed with the Gal4 driver was used as the control fly. Five different Gal4 drivers were utilized for transgene expression.Expression of mRNA and protein was confirmed with RT-PCR and western blot, respectively. Longevity analysis showed that expression in amyloid-associated lines TTRwt, TTRV30L, TTRV30M, and TTRL111M driven by fatbody-Gal4 decreased mean survival compared to the control fly. Hand-C-Gal4 drives the TTR expression in the cardioblasts and pericardial nephrocytes of the heart. In 30-day-old flies, a significantly reduced heart rate and a prolonged diastolic interval were observed in flies expressing TTRV30L and TTRV30M. In addition, arrhythmia was determined in flies expressing TTRV30L, TTRV30M, TTRA109S, and TTRL111M. The fractional shortening was significantly reduced in all flies except for TTRR104H and TTRA109T compared to controls (P <0.001). Nrv2-Gal4 drives the TTR protein in central and peripheral nerve cells. Locomotory analysis in twenty days old flies showed a later evening peak in flies expressing TTRV30L, TTRL55P, and TTRT119M than control flies. The results showed that different mutations give rise to different phenotypes. The SOHA analysis of free-dissected heart tubes can be an excellent technique for monitoring changes in flies with transgenic expression in this tissue. Analysis of movement showed different results depending on which Gal4 driver was used, which are why it is appropriate to include more than one type of Gal4 driver when studying aggregating proteins.
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| 44. |
- Kieninger, Barbara, et al.
(författare)
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PTAA and B10 : new approaches to amyloid detection in tissue-evaluation of amyloid detection in tissue with a conjugated polyelectrolyte and a fibril-specific antibody fragment
- 2011
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Ingår i: Amyloid. - : Informa UK Limited. - 1350-6129 .- 1744-2818. ; 18:2, s. 47-52
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Tidskriftsartikel (refereegranskat)abstract
- Methods: aEuro integral We compared the amyloid detection of PTAA and B10 to Congo red in 106 amyloid-containing tissue biopsies of diverse anatomical and precursor origin by evaluating the accordance in four grades (grade 0: no staining, grade 1: staining of < 33%% of the amyloid deposits, grade 2: 33--66%% and grade 3: aEuroS > 66%%). Results: aEuro integral PTAA showed grade 2--3 staining in 57 (54%%) cases, while B10 presented this accordance in only 25 (24%%) tissue biopsies. Grade 1 staining was found in 11 (10%%) samples with PTAA and in 62 (58%%) cases with B10. No staining at all (grade 0) occurred in 38 (36%%) biopsies when using PTAA and in 19 (18%%) cases when using B10. Conclusion: aEuro integral Although conformation-sensitive detection seemed promising, PTAA and B10 stain only a fraction of the examined amyloid samples when using routine surgical pathology settings. This study emphasises the necessity of having optimised pre-analytical protocols for recovery, storage and handling of samples if these novel amyloid ligands are to be used in routine diagnosis of amyloid.
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| 45. |
- Krizhanovskii, Camilla, et al.
(författare)
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Addition of exogenous sodium palmitate increases the IAPP/insulin mRNA ratio via GPR40 in human EndoC-beta H1 cells
- 2017
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 122:3, s. 149-159
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Tidskriftsartikel (refereegranskat)abstract
- Background: Enhanced IAPP production may contribute to islet amyloid formation in type 2 diabetes. The objective of this study was to determine the effects of the saturated fatty acid palmitate on IAPP levels in human beta-cells. Methods: EndoC-beta H1 cells and human islets were cultured in the presence of sodium palmitate. Effects on IAPP/insulin mRNA expression and secretion were determined using real-time qPCR/ELISA. Pharmacological activators and/or inhibitors and RNAi were used to determine the underlying mechanisms. Results: We observed that EndoC-beta H1 cells exposed to palmitate for 72 h displayed decreased expression of Pdx-1 and MafA and increased expression of thioredoxin-interacting protein (TXNIP), reduced insulin mRNA expression and glucose-induced insulin secretion, as well as increased IAPP mRNA expression and secretion. Further, these effects were independent of fatty acid oxidation, but abolished in response to GPR40 inhibition/downregulation. In human islets both a high glucose concentration and palmitate promoted increased IAPP mRNA levels, resulting in an augmented IAPP/insulin mRNA ratio. This was paralleled by elevated IAPP/insulin protein secretion and content ratios. Conclusions: Addition of exogenous palmitate to human beta-cells increased the IAPP/insulin expression ratio, an effect contributed to by activation of GPR40. These findings may be pertinent to our understanding of the islet amyloid formation process.
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| 46. |
- Krotee, Pascal, et al.
(författare)
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Atomic structures of fibrillar segments of hIAPP suggest tightly mated beta-sheets are important or cytotoxicity
- 2017
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Ingår i: eLIFE. - 2050-084X. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- hIAPP fibrils are associated with Type-II Diabetes, but the link of hIAPP structure to islet cell death remains elusive. Here we observe that hIAPP fibrils are cytotoxic to cultured pancreatic beta-cells, leading us to determine the structure and cytotoxicity of protein segments composing the amyloid spine of hIAPP. Using the cryoEM method MicroED, we discover that one segment, 19-29 S20G, forms pairs of beta-sheets mated by a dry interface that share structural features with and are similarly cytotoxic to full-length hIAPP fibrils. In contrast, a second segment, 15-25 WT, forms non-toxic labile beta-sheets. These segments possess different structures and cytotoxic effects, however, both can seed full-length hIAPP, and cause hIAPP to take on the cytotoxic and structural features of that segment. These results suggest that protein segment structures represent polymorphs of their parent protein and that segment 19-29 S20G may serve as a model for the toxic spine of hIAPP.
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| 47. |
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| 48. |
- Lundmark, Katarzyna, et al.
(författare)
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Depletion of Spleen Macrophages Delays AA Amyloid Development: A Study Performed in the Rapid Mouse Model of AA Amyloidosis
- 2013
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 8:11, s. e79104-
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Tidskriftsartikel (refereegranskat)abstract
- AA amyloidosis is a systemic disease that develops secondary to chronic inflammatory diseases Macrophages are often found in the vicinity of amyloid deposits and considered to play a role in both formation and degradation of amyloid fibrils. In spleen reside at least three types of macrophages, red pulp macrophages (RPM), marginal zone macrophages (MZM), metallophilic marginal zone macrophages (MMZM). MMZM and MZM are located in the marginal zone and express a unique collection of scavenger receptors that are involved in the uptake of blood-born particles. The murine AA amyloid model that resembles the human form of the disease has been used to study amyloid effects on different macrophage populations. Amyloid was induced by intravenous injection of amyloid enhancing factor and subcutaneous injections of silver nitrate and macrophages were identified with specific antibodies. We show that MZMs are highly sensitive to amyloid and decrease in number progressively with increasing amyloid load. Total area of MMZMs is unaffected by amyloid but cells are activated and migrate into the white pulp. In a group of mice spleen macrophages were depleted by an intravenous injection of clodronate filled liposomes. Subsequent injections of AEF and silver nitrate showed a sustained amyloid development. RPMs that constitute the majority of macrophages in spleen, appear insensitive to amyloid and do not participate in amyloid formation.
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| 49. |
- Ma, Zhi, et al.
(författare)
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Effects of free fatty acid on polymerization of islet amyloid polypeptide (IAPP) in vitro and on amyloid fibril formation in cultivated isolated islets of transgenic mice overexpressing human IAPP
- 2002
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Ingår i: Molecular Medicine. - 1076-1551 .- 1528-3658. ; 8:12, s. 863-868
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Islet amyloid polypeptide (IAPP) is deposited as amyloid in the islets of Langerhans in type 2 diabetes. The mechanism behind the formation of the cytotoxic fibrils is unknown. Islet amyloid develops in a mouse IAPP null mouse strain that expresses human IAPP (+hIAPP/-mIAPP) after 9 months on a high-fat diet. Herein we investigate the effect that individual free fatty acids (FFAs) exert on formation of amyloid-like fibrils from synthetic IAPP and the effects of FFAs on IAPP polymerization in +hIAPP/-mIAPP islets cultivated in vitro.MATERIALS AND METHODS: In the study myristic acid, palmitic acid, stearic acid, oleic acid, and linoleic acid were used together with albumin. Thioflavin T (Th T) assay was used for quantification of amyloid-like fibrils. Islets were isolated from the +hIAPP/-mIAPP transgenic strain and cultured in the presence of the FFAs for 2 days. Immuno-electron microscopy was used for evaluation.RESULTS: The Th T assay showed that all studied FFAs potentiated fibril formation but that myristic acid revealed the highest capacity. In some cells from cultured islets, intragranular aggregates were present. These aggregates had a filamentous appearance and labeled with antibodies against IAPP. In some cells cultured in the presence of linoleic acid, large amounts of intracellular amyloid were present. Earlier, this has not been observed after such a short incubation period.CONCLUSIONS: Our studies suggest that FFAs can potentiate amyloid formation in vitro, probably without being integrated in the fibril. Cultivation of +hIAPP/-mIAPP transgenic mouse islets with FFAs results in altered morphology of the secretory granules with appearance of IAPP- immunoreactive fibrillar material. We suggest that such fibrillar material may seed extracellular amyloid formation after exocytosis.
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| 50. |
- Nilsson, K. Peter R., et al.
(författare)
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Imaging distinct conformational states of amyloid-beta fibrils in Alzheimer's disease using novel luminescent probes
- 2007
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Ingår i: ACS Chemical Biology. - : American Chemical Society (ACS). - 1554-8929 .- 1554-8937. ; 2:8, s. 553-560
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Tidskriftsartikel (refereegranskat)abstract
- Using luminescent conjugated polyelectrolyte probes (LCPs), we demonstrate the possibility to distinguish amyloid-β 1–42 peptide (Aβ1–42) fibril conformations, by analyzing in vitro generated amyloid fibrils of Aβ1–42 formed under quiescent and agitated conditions. LCPs were then shown to resolve such conformational heterogeneity of amyloid deposits in vivo. A diversity of amyloid deposits depending upon morphology and anatomic location was illustrated with LCPs in frozen ex vivo brain sections from a transgenic mouse model (tg-APP swe) of Alzheimer’s disease. Comparative LCP fluorescence showed that compact-core plaques of amyloid β precursor protein transgenic mice were composed of rigid dense amyloid. A more abundant form of amyloid plaque displayed morphology of a compact center with a protruding diffuse exterior. Surprisingly, the compact center of these plaques showed disordered conformations of the fibrils, and the exterior was composed of rigid amyloid protruding from the disordered center. This type of plaque appears to grow from more loosely assembled regions toward solidified amyloid tentacles. This work demonstrates how application of LCPs can prove helpful to monitor aggregate structure of in vivo formed amyloid deposits such as architecture, maturity, and origin.
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