PubMed Health⌕ Search

Biomedical subjects

Per Westermark

Publications and source records attributed to Per Westermark.

At least 19 recordsLinked to original sources
PubMed2006

Surface exposed epitopes and structural heterogeneity of in vivo formed transthyretin amyloid fibrils.

We have investigated the structure of in vivo formed transthyretin (TTR) amyloid deposits by using antisera raised against short linear sequences of the TTR molecule. In immunohistochemistry, antisera anti-TTR41-50 and anti-TTR115-124-a reacted specifically with both wildtype ATTR and ATTR V30M material, whereas only anti-TTR41-50 recognized ATTR Y114C material. Similar results were obtained by ELISA analysis of ATTR V30M and ATTR Y114C vitreous amyloid, where the anti-TTR115-124-a antiserum failed to react with ATTR Y114C material. Moreover, neither of the antisera recognized natively structured TTR present in pancreatic alpha cells. Our results strongly indicate that the TTR molecule undergoes structural changes during fibrillogenesis in vivo. The finding of a structural difference between wildtype ATTR and ATTR V30M material on one hand and ATTR Y114C material on the other suggests that the fibril formation pathway of these ATTR variants may differ in vivo.

Amino Acid Sequence↗
PubMed2006

Subcutaneous fat tissue for diagnosis and studies of systemic amyloidosis.

The systemic amyloidoses comprise a biochemically heterogeneous group of potentially lethal disorders. An early and precise diagnosis is crucial for the treatment and prognosis. Subcutaneous fat biopsy is a simple and safe method to obtain a diagnosis of systemic amyloidosis and the material can be used for exact determination of amyloid type. A method is described for immunochemical typing of the amyloid based on Western blot analysis combined with specific amyloid fibril protein antibodies.

Adipose Tissue↗
PubMed2006

Amyloid contained in the knee joint meniscus is formed from apolipoprotein A-I.

OBJECTIVE: To determine the chemical nature of amyloid deposits found in knee joint menisci. METHODS: Amyloid was extracted from the menisci of 3 adults who underwent knee joint replacement surgery. The primary structural features of the purified proteins were determined by sequential Edman degradation and tandem mass spectrometry (MS/MS). Tissue specimens were also subjected to in situ hybridization analysis, as well as complementary DNA cloning by reverse transcriptase-polymerase chain reaction (RT-PCR). Additionally, specimens from these 3 patients, as well as other patients with amyloid in the knee joint menisci, were examined immunohistochemically. RESULTS: Amino acid sequence and MS/MS analyses of the extracts revealed the presence of 60-77-residue components identical to the N-terminal portion of apolipoprotein A-I (Apo A-I). The Apo A-I nature of the amyloid was confirmed by the demonstration that the green birefringent congophilic deposits in the 7 meniscus samples were recognized by an anti-human Apo A-I antibody. That the meniscus itself was the source of the amyloidogenic protein was evidenced through Southern blot analysis, in which an Apo A-I product was generated by RT-PCR from synovial tissue, and further, by the demonstration that the cytoplasm of chondrocytes reacted with the specific Apo A-I probe used for in situ hybridization and was immunostained by the anti-Apo A-I antiserum. CONCLUSION: Amyloid in the knee joint menisci is formed from Apo A-I that is produced by chondrocytes within the meniscal cartilage. This entity represents yet another localized form of amyloidosis associated with the aging process and may be of pathophysiologic import.

Adult↗
PubMed2006

Immunoaffinity chromatographic and immunoprecipitation methods combined with mass spectrometry for characterization of circulating transthyretin.

Transthyretin (TTR) is a small serum protein that is involved in distinct phenotypes of amyloidosis with different tissue localization, age of onset, and rate of progression. Some types of TTR-amyloidosis (such as familial amyloid polyneuropathy) are associated with various amino acid point mutations, while cardiac amyloid myopathy may also be associated with precipitation of the wild-type molecules, e.g., in senile systemic amyloidosis. Because of the unsettled relationship between circulating and precipitated TTR we here explore on-line immunoaffinity (IA) chromatography-MS and immunoprecipitation (IP)-MS methods for characterizing the circulating TTR population in normal individuals and in patients with known TTR-amyloidosis. It was found necessary to reduce the samples, e.g., with DTT, prior to ESI-TOF-MS. This reversed oxidative modifications to sufficiently resolve the two mass peaks isolated from sera of heterozygous patients. A simple IP technique without the use of centrifugal filtration was found to be convenient for the assessment of the TTR population in serum as demonstrated for both normal and variant (the Met111Leu mutation) TTR. This approach also readily allowed the identification of oxidation, S-sulfation, and S-cysteinylation in unreduced samples, while these modifications were less well resolved in the on-line IA chromatography-MS approach.

Amyloid Neuropathies, Familial↗
PubMed2006

Lactadherin binds to elastin--a starting point for medin amyloid formation?

Medin amyloid is found in the medial layer of the aorta in almost 100% of the Caucasian population over 50 years of age. The medin fragment is 5.5 kDa and derives from the C2-like domain of the precursor protein lactadherin. We have previously reported immunohistochemical findings showing that medin amyloid co-localizes with elastic fibers of arteries and herein we show that lactadherin also is associated with elastic structures of human aortic material. In addition, results from in vitro binding assays demonstrate that both medin and lactadherin bind to tropoelastin in a concentration-dependent fashion, suggesting that the lactadherin-tropoelastin interaction is mediated via the medin domain. It is possible that lactadherin, which is a cell adhesion protein, in this way connects smooth muscle cells to the elastic fibers of arteries. Given that both medin and lactadherin interact with elastic fibers, elastin is probably an important component in the formation of medin amyloid.

Amyloid↗
PubMed2005

Protein fibrils in nature can enhance amyloid protein A amyloidosis in mice: Cross-seeding as a disease mechanism.

Secondary, or amyloid protein A (AA), amyloidosis is a complication of chronic inflammatory diseases, both infectious and noninfectious. AA constitutes the insoluble fibrils, which are deposited in different organs, and is a major N-terminal part of the acute phase protein serum AA. It is not known why only some patients with chronic inflammation develop AA amyloidosis. Nucleation is a widely accepted mechanism in amyloidogenesis. Preformed amyloid-like fibrils act as nuclei in amyloid fibril formation in vitro, and AA amyloid fibrils and synthetic amyloid-like fibrils also may serve as seed for fibril formation in vivo. In addition to amyloid fibrils, there is a variety of similar nonmammalian protein fibrils with beta-pleated structure in nature. We studied three such naturally occurring protein fibrils: silk from Bombyx mori, Sup35 from Saccharomyces cerevisiae, and curli from Escherichia coli. Our results show that these protein fibrils exert amyloid-accelerating properties in the murine experimental AA amyloidosis, suggesting that such environment factors may be important risk factors in amyloidogenesis.

Actins↗
PubMed2005

Amyloid deposits in transthyretin-derived amyloidosis: cleaved transthyretin is associated with distinct amyloid morphology.

The pathological fibrillar deposits found in the heart and other organs of patients with senile systemic amyloidosis (SSA) and Swedish familial amyloidotic polyneuropathy (FAP) contain wild-type (wt) and a mutant form of transthyretin (TTR), respectively. Previously, it was reported that these two forms of amyloid have different molecular features and it was thus postulated that the mechanism responsible for TTR fibrillogenesis in SSA and FAP may differ. To document further the nature of the amyloid in these entities, detailed morphological, histochemical, immunological, and structural analyses of specimens obtained from 14 individuals with SSA and 11 Swedish FAP patients have been performed. Two distinct patterns of amyloid deposition (designated A and B) were evident. In pattern A, found in all SSA and five of 11 FAP cases, the amyloid had a homogeneous but patchy distribution within the sub-endocardium, sub-epicardium, and myocardium; exhibited weak congophilia and green birefringence; and was composed of tightly packed, short, unorientated fibrils. This material contained mainly approximately 79-residue C-terminal fragments of the amyloidogenic precursor protein. In pattern B, seen in the six other FAP patients, the amyloid appeared as thin streaks throughout the cardiac tissue; often surrounded individual muscle cells; was strongly congophilic and birefringent; had long fibrils arranged in parallel bundles, often penetrating into myocytes; and was composed of virtually intact TTR molecules. These findings provide substantive evidence for the morphological and structural heterogeneity of TTR fibrils and suggest that the two types of deposition may reflect fundamental differences in the pathogenesis of the TTR-associated amyloidoses.

Adult↗
PubMed2005

Is aggregated IAPP a cause of beta-cell failure in transplanted human pancreatic islets?

Aggregation of the beta-cell product islet amyloid polypeptide (IAPP) is believed to be an important event in the development of the beta-cell lesion in type 2 diabetes. Preamyloidotic oligomeric IAPP assemblies exert toxic effects on beta cells that die, leading to reduced beta-cell mass. Normal human islets, when isolated and cultured in vitro or transplanted into nude mice, also develop amyloid deposits, which are associated with increased beta-cell death and reduced beta-cell mass. The possible role of IAPP aggregation and amyloid formation in loss of islet transplant function should be taken into consideration and studied further.

Amyloid↗
PubMed2005

Senile seminal vesicle amyloid is derived from semenogelin I.

Senile seminal vesicle amyloid (SSVA), one of the most common forms of localized amyloidosis, is associated with the male aging process. Although it had been posited that the amyloidogenic component originated from exocrine cells and that, on the basis of immunohistochemistry, that the amyloid was composed of lactoferrin, the nature of SSVA was never established definitively. To address this issue, we have used our microanalytic techniques to characterize the structure of the congophilic green birefringent protein extracted from 5 such amyloid-containing specimens. Mass spectrometric analysis revealed that in all cases, the fibrils were composed mainly of polypeptide fragments identical in sequence to the N-terminal portion of the major secretory product of seminal vesicles, namely semenogelin I (SgI). Although lactoferrin was detected in 3 instances, the trace amount and seemingly intact form of this molecule indicated that it was not the amyloidogenic molecule. The SgI nature of the amyloid was confirmed through demonstration that the deposits were immunostained specifically with Sgl-reactive antibodies. The results of our research provide unequivocal evidence that SSVA is derived from SgI, and we provisionally designate this form of amyloidosis as ASgI.

Aged↗
PubMed2005

Amyloid: toward terminology clarification. Report from the Nomenclature Committee of the International Society of Amyloidosis.

The modern nomenclature of amyloidosis now includes 25 human and 8 animal fibril proteins. To be included in the list, the protein has to be a major fibril protein in extracellular deposits, which have the characteristics of amyloid, including affinity for Congo red with resulting green birefringence. Synthetic fibrils with amyloid properties are best named 'amyloid-like'. With increasing knowledge, however, the borders between different protein aggregates tend to become less sharp.

Amyloid↗
PubMed2005

Medin-amyloid: a recently characterized age-associated arterial amyloid form affects mainly arteries in the upper part of the body.

Amyloid deposition occurs commonly in the aging aortic media. We recently found that a 50 amino acid amyloid fibril protein, which we called medin, forms the fibrils of this amyloid form. Medin is an internal fragment of the 364 long precursor lactadherin, which is expressed by several kinds of cells including vascular smooth muscle cells. With the use of specific antibodies we have now studied the vascular distribution of medin (AMed) amyloid in a series of 18 individuals, 57 years of age and older. All individuals had widely spread AMed amyloid in the media of the thoracic aorta while this type of amyloid occurred less commonly in the abdominal aorta. In 8 of the 18 individuals, AMed-amyloid was also found in the basilar artery while the frequency was lower in other studied arteries. Amyloid was usually seen in close association with the internal elastic lamina. Analysis of proteins extracted from amyloid-rich aortic media showed presence of both lactadherin and medin. This study shows that AMed amyloid is not restricted to the aorta and the temporal artery but also occurs in other arteries, mainly in the upper part of the body. AMed amyloid has to be added to the forms of amyloid that may be seen in intracranial vessels.

Aged↗
PubMed2005

A Swedish family with the rare Phe33Leu transthyretin mutation.

Familial amyloidotic polyneuropathy (FAP) designates TTR mutations where the phenotype is dominated by a peripheral sensory-motor polyneuropathy. The most common mutation is ATTR Val30Met. FAP in association with ATTR Phe33Leu has been described previously in two American families, one of Polish-Lithuanian descent and the other of Polish-American. In this study, we report the phenotype of the ATTR Phe33Leu in a Swedish family. The proband is a 48 year-old patient from northern Sweden, whose father died with symptoms suggestive of FAP. Characteristic clinical features included polyneuropathy, carpal tunnel syndrome and asymptomatic, but echocardiographic examination diagnosed cardiomyopathy. The family history supports an early intervention with orthotopic liver transplantation in patients with FAP associated with the TTR Phe33Leu, and the patient was submitted for liver transplantation.

Amyloid Neuropathies, Familial↗
PubMed2005

Aspects on human amyloid forms and their fibril polypeptides.

Amyloid is an in vivo fibrillar substance containing a fibril protein and several additional molecules. Presently, 25 proteins have been reported as main fibril components. Why just a few proteins form amyloid in vivo is still insufficiently understood. Many fibril proteins appear as fragments of larger precursors and for some types it is not clear whether fragmentation comes before or after fibrillation. The self-assembly by amyloid proteins can be speeded up by seeding with preformed fibrils. In mice, systemic amyloidoses are transmissible by a seeding mechanism. Whether this prion-like mechanism occurs in humans is not known, but can definitely not be ruled out.

Amyloid↗
PubMed2005

Purification of amyloid protein AA subspecies from amyloid-rich human tissues.

Protein AA, the major amyloid fibril protein in reactive (secondary) systemic amyloidosis is derived from the acute phase reactant liver-produced apolipoprotein serum AA (SAA) by proteolytic cleavage, usually in the C-terminal half of the 104 amino acid residues long precursor. The cleavage points in SAA vary between patients and the deposited protein AA is often quite heterogeneous. In this chapter, we describe methods to extract amyloid fibrils and to purify protein AA by sequential gel filtration. Further purification of subspecies of protein AA is best achieved by the use of differences in charge and chromatofocusing is described as the method of choice. Analytic methods include sodium dodecylsulfate polyacrylamide gel electrophoresis and analytic isoelectric focusing.

Humans↗
PubMed2005

Purification of transthyretin and transthyretin fragments from amyloid-rich human tissues.

Transthyretin is the major amyloid fibril protein in many forms of familial systemic amyloidosis where a missense mutation creates an amyloidogenic protein, and in senile systemic amyloidosis in which wild-type transthyretin aggregates into amyloid fibrils. The amyloid deposits may consist of full-length transthyretin but is very often, in senile systemic amyloidosis always, a mixture of full-length transthyretin and C-terminal transthyretin fragments. The amyloid fibril protein mixture can be purified by extraction of fibrils followed by sequential gel filtration after solubilization in a solution of guanidine hydrochloride. Since the C-terminal transthyretin fragments lack cysteine residues, a method to separate full-length transthyretin from fragments by covalent chromatography has been developed.

Chromatography↗
PubMed2004

Seeding specificity in amyloid growth induced by heterologous fibrils.

Over residues 15-36, which comprise the H-bonded core of the amyloid fibrils it forms, the Alzheimer's disease plaque peptide amyloid beta (Abeta) possesses a very similar sequence to that of another short, amyloidogenic peptide, islet amyloid polypeptide (IAPP). Using elongation rates to quantify seeding efficiency, we inquired into the relationship between primary sequence similarity and seeding efficiency between Abeta-(1-40) and amyloid fibrils produced from IAPP as well as other proteins. In both a solution phase and a microtiter plate elongation assay, IAPP fibrils are poor seeds for Abeta-(1-40) elongation, exhibiting weight-normalized efficiencies of only 1-2% compared with Abeta-(1-40) fibrils. Amyloid fibrils of peptides with sequences completely unrelated to Abeta also exhibit poor to negligible seeding ability for Abeta elongation. Fibrils from a number of point mutants of Abeta-(1-40) exhibit intermediate seeding abilities for wild-type Abeta elongation, with differing efficiencies depending on whether or not the mutation is in the amyloid core region. The results suggest that amyloid fibrils from different proteins exhibit structural differences that control seeding efficiencies. Preliminary results also suggest that identical sequences can grow into different conformations of amyloid fibrils as detected by seeding efficiencies. The results have a number of implications for amyloid structure and biology.

Amino Acid Sequence↗
PubMed2004

Two different types of amyloid deposits--apolipoprotein A-IV and transthyretin--in a patient with systemic amyloidosis.

Certain forms of systemic amyloidosis have been associated with the pathologic deposition as fibrils of three different apolipoprotein-related proteins--apolipoprotein A-I, apolipoprotein A-II, and serum amyloid A. We have previously reported (Bergström et al, Biochem Biophys Res Commun 2001;285:903-908) that amyloid fibrils extracted from the heart of an elderly male with senile systemic amyloidosis contained, in addition to wild-type transthyretin-related molecules, an N-terminal fragment of yet a fourth apolipoprotein--apolipoprotein A-IV (apoA-IV). We now provide the results of our studies that have established the complete amino-acid sequence of this approximately 70-residue component and, additionally, have shown this protein to be the product of an unmutated apoA-IV gene. Notably, the apoA-IV and transthyretin fibrils were not codeposited but, rather, had anatomically distinct patterns of distribution within the heart and other organs, as evidenced immunohistochemically, by variation in the ultra structural morphology and by differences in the intensity of Congo red birefringence. These findings provide the first conclusive evidence that two separate forms of amyloid, each derived from a wild-type amyloidogenic precursor protein, were present in a patient with systemic amyloidosis.

Aged↗