AA Deposition Research Articles

Effect of chronic administration of arachidonic acid on the performance of learning and memory in aged rats.

BackgroundArachidonic acid (AA, C20:4, ω-6) is a ω-6 polyunsaturated fatty acid (PUFA) and plays diverse roles in cell signaling. Numerous reports on the effects of ω-3 PUFAs, such as docosahexaenoic acid (DHA, C22:6, ω-3) and eicosapentaenoic acid (EPA, C20:5, ω-3) on learning and memory impairments of rats are available, however, the role of AA on brain cognition is largely unknown.ObjectiveIn this study, our aim was to investigate the effect of oral administration of AA on spatial memory-related learning ability in aged (100 weeks) male rats.DesignOne group was per orally administered 240 mg/kg per day AA oil and the other group was administered the similar volume of control oil. Five weeks after the start of the administration, rats were tested with the partially baited eight-arm radial maze to evaluate two types of spatial memory-related learning ability displayed by reference memory errors (RMEs) and working memory errors (WMEs). Also, the time required to complete the task was recorded. The levels of lipid peroxide (LPO) and reactive oxygen species (ROS) were measured, as an indicator oxidative stress in the plasma and brain corticohippocampal brain tissues.ResultsThe scores of RMEs and WMEs, which are analogous to long-term and short-term memory, respectively, were not affected, however, the trial time was shorter in the AA-administered rats than that of the controls. AA also significantly increased the degree of oxidative stress both in the plasma and corticohippocampal brain tissues.ConclusionsOur results suggest that though AA deposition in the corticohippocampal tissues of senescent rats caused a faster performance activity, which is reminiscent to hyperactive behavior of animals, the spatial learning ability-related memory of the rats, however, was not improved.

Long-term kinetics of AA amyloidosis and effects of inflammatory restimulation after disappearance of amyloid depositions in mice.

Amyloid A (AA) amyloidosis is characterized by extracellular pathogenic deposition of insoluble fibril protein in various body organs. Deposited amyloid generally remains in a variety of organs for long periods, but its disappearance has been reported after the precursor protein is diminished. The kinetics of AA deposition are not completely understood and, in particular, the roles of cells and cytokines in the deposition and clearance of amyloid remain unclear. In this study, we investigated the disappearance of amyloid depositions in mice over a 1-year period. AA amyloidosis was induced experimentally in mice by injecting amyloid-enhancing factor (AEF) and silver nitrate. Mice were killed at different time-points to examine the occurrence and disappearance of amyloid depositions. Maximum levels of amyloid depositions were observed at 20 days after inoculation. Clearance of amyloid depositions was observed from the 40th day onwards, with only minute traces of amyloid present by 240 days. A second inflammatory stimulus consisting of AEF and silver nitrate was given at 330 or 430 days, after amyloid depositions had disappeared almost completely. After that, serum amyloid A was overproduced and redeposition of amyloid was observed, indicating that all mice were primed for aggressive amyloid depositions. After administration of the inflammatory stimuli, the proinflammatory environment was found to have increased levels of interleukin (IL)-6, while anti-inflammatory conditions were established by IL-10 as regression of amyloid deposition occurred. These results suggest that the proinflammatory and anti-inflammatory status have key roles in both amyloid deposition and clearance.

Biopsy Proven Non-Amyloid Glomerular Diseases in Patients With Familial Mediterranean Fever

AIM: Kidney involvement is the most serious organ involvement of Familial Mediterranean Fever (FMF), while the most common cause is AA type amyloidosis with serum amyloid AA deposition. However, vasculitis and other types of glomerulonephritis (GN) also have been reported. With this study we evaluated biopsy proven non-amyloid glomerular diseases in patients with FMF. Methods: At our Nephrology clinic, total 950 patients followed by diagnosis of FMF have been evaluated. Nine patients who had positive proteinuria ( >500 mg/day) but had negative amyloidosis in the tissue biopsy were made renal biopsy. Results: Nine patients underwent a renal biopsy, two patients were found to have IgA nephropathy (IGAN), three mesangioproliferative glomerulonephritis (MsPGN), three membranous glomerulonephritis (MGN) and one had immune complex glomerulonephritis. Two patients with IGAN and one patient with MGN with non-nephrotic proteinuria exhibited significant improvement with colchicine and angiotensin receptor blocker (ARB) therapy. Other patients were treated with colchicine, an ARB and immunosuppressive drugs. Upon evaluation for the FMF gene mutation, different mutations have been found for the same glomerulonephritis type. Conclusions: Other glomerular causes also must be investigated alongside amyloidosis in the case of kidney involvement in FMF patients. While patients with IGAN and other glomerulonephrities with non-nephrotic proteinuria can respond well to colchicine treatment, patients with more aggressive kidney involvement may require immunosuppressive therapy. Further studies are needed for revealing the relationship between FMF gene mutation and non-amyloid glomerular diseases.

AB0069 Mechanism Elucidation of Effectiveness of IL-6 Blockade for Reduction of SAA Production and Amyloid A Deposition in AA Amyloidosis Patients with RA

BackgroundAA amyloidosis is a serious complication of chronic inflammatory and infectious diseases resulting from the deposition of amyloid A protein. Serum amyloid A (SAA), a precursor molecule of AA protein...

Signs of cross-seeding: aortic medin amyloid as a trigger for protein AA deposition

The highly diverse deposition pattern displayed by systemic amyloidoses, sometimes within the same amyloid disease, remains unexplained. The localized medin (AMed) amyloidosis develops from the precursor protein lactadherin and deposits in the media of the thoracic aorta in almost all individuals above 50 years of age. Given its high prevalence in the population, and the fact that systemic amyloidoses also deposit in the aorta, led us to investigate whether AMed amyloid could influence the tissue distribution of serum amyloid A derived (AA) amyloidosis. Seven aortas from patients with diagnosed systemic AA amyloidosis were investigated. Four displayed partial co-localization between medin and AA aggregates when examined with double-labeling immunofluorescence. Furthermore, in vitro studies showed that AMed amyloid-like fibrils promote the aggregation of protein AA into fibrils. The findings indicate that the highly frequent “senile” amyloidoses may have the potential to initiate fibril formation of the more uncommon amyloidoses by a cross-seeding mechanism.

Effects of Dietary Arachidonic Acid (20:4n-6) Levels on Growth Performance and Fatty Acid Composition of Juvenile Eel, Anguilla japonica

This study was conducted to evaluate the effects of dietary arachidonic acid (AA, 20:4n-6) levels on growth performance and body composition in juvenile eel, Anguilla japonica. Six semi-purified experimental diets were formulated to be isonitrogenous and iso-caloric containing 55.0% crude protein and 15% crude lipid (18.3 kJ of available energy g -1 ). Six different levels of AA were added to the basal diet, with 0, 0.2, 0.4, 0.6, 0.8 or 1.2% on a dry matter (DM) basis, respectively (AA 0.07 , AA 0.22 , AA 0.43 , AA 0.57 , AA 0.78 or AA 1.23 ). After a conditioning period, fish initially averaging 27±0.5 g (mean±SD) were randomly distributed into each aquarium as triplicate groups of 20 fish each. One of six experimental diets was fed on a DM basis to fish in three randomly selected aquaria at a rate of 2-3% of total body weight twice a day. At the end of the 12-week feeding trial, weight gain (WG) and feed efficiency (FE) of fish fed AA 0.78 and AA 1.23 diets were significantly higher than of fish fed AA 0.07 , AA 0.22 and AA 0.43 diets (p 0.05). Whole body AA deposition of fish fed the AA 1.23 diet was significantly higher than for the other diets (p<0.05). Broken-line model analysis on the basis of WG and SGR indicated that the dietary AA requirement could be greater than 0.69% but less than 0.71% of the diet in juvenile eel. The growth-promoting activity of AA observed in the present study provides strong support for the contention that dietary AA is essential for juvenile eel.

AADE Position Statement

AADE Position Statement

Quantitative high-resolution microradiographic imaging of amyloid deposits in a novel murine model of AA amyloidosis

The mouse model of experimentally induced systemic AA amyloidosis is long established, well validated, and closely analogous to the human form of this disease. However, the induction of amyloid by experimental inflammation is unpredictable, inconsistent, and difficult to modulate. We have previously shown that murine AA amyloid deposits can be imaged using iodine-123 labeled SAP scintigraphy and report here substantial refinements in both the imaging technology and the mouse model itself. In this regard, we have generated a novel prototype of AA amyloid in which mice expressing the human interleukin 6 gene, when given amyloid enhancing factor, develop extensive and progressive systemic AA deposition without an inflammatory stimulus, i.e., a transgenic rapidly inducible amyloid disease (TRIAD) mouse. Additionally, we have constructed high-resolution micro single photon emission computed tomography (SPECT)/computed tomography (CT) instrumentation that provides images revealing the precise anatomic location of amyloid deposits labeled by radioiodinated serum amyloid P component (SAP). Based on reconstructed microSPECT/CT images, as well as autoradiographic, isotope biodistribution, and quantitative histochemical analyses, the 125I-labeled SAP tracer bound specifically to hepatic and splenic amyloid in the TRIAD animals. The ability to discern radiographically the extent of amyloid burden in the TRIAD model provides a unique opportunity to evaluate the therapeutic efficacy of pharmacologic compounds designed to inhibit fibril formation or effect amyloid resolution.

Alveolar Hydatid Cyst (AHC): Inflammation-Induced Reactive Gastrointestinal (GI) Amyloidosis in AHC-Infected Mice and Chemical Characterization of the GI Amyloid

A high incidence of GI amyloidosis has been described in patients with various forms of systemic amyloidosis but its evolution and progression in different subregions of the GI tract are not well documented. These aspects including the chemical nature of GI amyloid were examined in the AHC mouse model of inflammation-associated reactive amyloidosis. C57BL/6 mice were infected intraperitoneally with 250 AHC. Paraffin sections from the stomach and the small and large intestines of AHC mice were stained at different time intervals with Congo red or immunocytochemically with monospecific RAA. The submucosal blood vessels at 1 week postinfection were found to be the first target of amyloid deposition. With time the amyloid deposits extended to the mucosa and the Peyer's patches and immunoreacted with RAA; ileum was the most severely affected region. Amyloid was extracted from the GI tract and purified by size exclusion chromatography using 5Mguanidine–formic acid, pH 3. The purified amyloid was identified by Western blotting using RAA and by partial N-terminal microsequencing up to 10 cycles. The GI amyloid showed homology with murine SAA2, although SAA2mRNA is not expressed in murine GI tract. These results show that (a) the GI amyloid is derived, similar to that of splenic/hepatic amyloid, from circulating SAA2and (b) the GI tract submucosal blood vessels are the first target of AA deposition. The data also suggest that AA-mediated damage to the submucosal blood capillaries may lead to SAA leakage followed by cascading of AA deposition in other layers of the GI tract.

AADE Position Statement: Medical Nutrition Therapy for People with Diabetes Mellitus

AADE Position Statement: Medical Nutrition Therapy for People with Diabetes Mellitus

Colocalization of ubiquitin and serum amyloid A and ubiquitin-bound AA in the endosomes-lysosomes: A double immunogold electron microscopic study

Alveolar hydatid cyst infection in mice induces multiple organ AA deposition at 1 week postinfection (p.i.) and increased expression of ubiquitin (UB) in both free and fixed monocytoid cells. We examined the distribution of UB, serum amyloid A and AA at 1 week p.i. in splenic perifollicular reticuloendothelial (SP-RE) cells using double immunogold electron microscopy. One side of the grid bearing the ultrathin sections was immunostained with chicken anti-bovine UB IgG-rabbit anti-chicken IgG conjugated to 6 nm colloidal gold and the other side with rabbit anti-mouse AA IgG-goat anti-rabbit IgG conjugated to 15 nm colloidal gold. Two major patterns of gold labeling were observed. The 6 nm particles, indicative of UB, labeled cytoplasmic and various subcellular orgenelles in SP-RE cells. Co-deposition of 6 and 15 nm particles, the latter indicative of AA epitope reactivity, was restricted to dense endosomes-lysosomes (EL), intravesicular “stumpy” and extracellular slender AA fibrils. Sections reacted with t...

Amyloid enhancing factor activity is associated with ubiquitin.

Crude amyloid enhancing factor (AEF) drastically reduces the pre-amyloid phase on passive transfer and induces amyloid deposition in the recipient mice in 48-120 h. We attempted to purify AEF from murine amyloidotic liver and spleen extracts by using gel filtration, preparative sodium dodecyl sulphate-polyacrylamide gel electrophoresis and ion exchange chromatography and isolated a 5.5 kDa peptide. In the mouse bioassay, this peptide induced accelerated splenic AA deposition in a dose-dependent manner. Based on structural, electrophoretic and immunochemical criteria the peptide was identified as ubiquitin. A polyclonal rabbit anti-bovine ubiquitin IgG antibody (RABU) abolished the in vivo AEF activity of crude murine AEF in a dose-dependent manner. Monomeric ubiquitin and its large molecular weight adducts were isolated from crude AEF using cyanogen bromide-activated sepharose conjugated to RABU and size exclusion chromatography methods. These were assayed and were found to possess AEF activity. Furthermore, increased levels of ubiquitin, a phenomenon similar to that of AEF, were detected by immunocytochemistry in mouse peritoneal leucocytes prior to and during amyloid deposition. Since AEF shares a number of biological and functional properties with ubiquitin, we suggest a possible role of ubiquitin as an AEF, and that serum amyloid protein A and ubiquitin, the two reactants generated during inflammatory stress conditions, may converge to induce AA amyloid deposition.

Effects of culture substrates and normal hepatic sinusoidal cells on in vitro hepatocyte synthesis of Apo-SAA.

Primary hepatocyte cultures synthesize apo-SAA upon stimulation with supernatant from lipopolysaccharide (LPS)-treated macrophages. The matrices on which the hepatocytes were grown influence their basal apo-SAA synthetic capability. Fibronectin was superior. Coculturing hepatocytes with hepatic sinusoidal cells did not adversely affect the ability of hepatocytes to synthesize and secrete apo-SAA into the culture medium. In 72 h, clear islands of endothelial cells nestled in layers of hepatocytes. Both apo-SAA and apo-SAA were made in considerable quantities but no evidence could be obtained that the apo-SAA were free of apo-A-1. The coculturing of hepatocytes with liver sinusoidal cells, the site of ultimate AA deposition, is a first step in establishing an in vitro system for AA amyloidogenesis.

Amyloidogenesis. One serum amyloid A isotype is selectively removed from the circulation.

The deposits of fibrils found in amyloidosis of the A type are derived from only one of the three serum amyloid A (SAA) gene products, namely SAA2. In order to explore the mechanism of SAA isotype-specific amyloid protein AA deposition, the molecular kinetics of the serum amyloid proteins were examined in CBA mice during casein induction of amyloidosis. The presence of SAA mRNA in spleen was searched for; hepatic SAA1 and SAA2 mRNA levels, rates of specific protein synthesis and secretion by hepatocytes, and serum levels were measured during a 20-d period of amyloid induction. We observed the following: small amounts of amyloid substance appeared in the spleen by day 5 and increased steadily over the ensuing 15 d to occupy nearly 30% of splenic volume by day 20. No SAA mRNA was detected in spleen at any time during induction of amyloid formation. Total serum SAA levels peaked 1 d after we began casein treatment, and thereafter declined. This decline was accounted for entirely by a dramatic fall in SAA2, while SAA1 levels remained nearly constant throughout. The ratios of hepatic SAA2:SAA1 mRNA, as determined by in vitro translation, remained constant during the 20-d period, as did amounts of SAA1 and SAA2 synthesized and secreted by freshly isolated hepatocytes. These data indicate that the deposition of amyloid A protein derived from SAA2 is not due to local SAA production in spleen, nor excessive SAA2 production compared with SAA1, but involves the selective and accelerated removal of SAA2 from the circulating pool of both SAA1 and SAA2.