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PubMed1989

Loss of virulence in Shigella strains preserved in culture collections due to molecular alteration of the invasion plasmid.

Fifty-two Shigella strains long preserved by three Japanese culture collections were examined for virulence. All of them were avirulent when judged by the focus-plaque assay and the ability to bind Congo red. Fifteen strains had a plasmid comparable in size to that responsible for epithelial invasiveness and were positive in hybridization tests with a probe derived from a plasmid cistron, virG. Twenty-four strains had a similar plasmid but were negative in hybridization tests. The remaining 13 strains were negative in all the five criteria for virulence. Similar studies made on one hundred Shigella strains isolated from 1967 to 1985 clearly demonstrated loss of virulence with prolonged time of storage.

DNA, Bacterial↗
PubMed1993

Amyloid formation by salmon calcitonin.

It is demonstrated using three independent methods that salmon calcitonin can form amyloid fibrils in vitro. Large aggregates are shown to exhibit a blue-green birefringence in cross polarised light after staining with congo red. Individual fibrils were observed using electron microscopy. These fibrils are approx. 50-60 A in diameter and up to 20,000 A in length and are similar in appearance to those observed in Alzheimer's disease. Finally, X-ray diffraction studies of the large aggregates reveal the cross-beta conformation characteristics of the monomers in the fibre.

Amyloid↗
PubMed2006

Case report: amyloid tumors in a case of non-secretory multiple myeloma.

Multiple myeloma (MM) is a neoplastic disorder characterized by proliferation of a single clone of plasma cells derived from B cells, which proliferates in the bone marrow and frequently invades the adjacent bone, producing skeletal destruction that results in bone pain and fractures. Patients with MM can furthermore present with anemia, hypercalcemia and renal failure. Non-secretory multiple myeloma (NSMM) is characterized by the absence of a monoclonal (M) protein in both the serum and urine. The reported incidence is 1-5% of all multiple myeloma cases. Development of amyloid tumors in NSMM has been described in the literature only occasionally. The clinical features of a 49-year-old female patient with NSMM and amyloid tumors in the breast, lung and rib are presented in this report. Conventional histology, Congo red staining with and without potassium permanganate pretreatment, aldehyde bisulfite-toluidine blue (ABT) reaction, sialic acid specific topo-optical reaction, toluidine blue topo-optical reaction as well as immunohistochemistry were performed. An attempt is made to explain the lack of monoclonal immunoglobulins in the serum and urine, although extensive organ amyloidosis of AL type (kappa-light chains) has been found. It is assumed that the plasmocytic plasma cells possess an excretory mechanism, which allows the pathologic immunoglobulins to be secreted either as amyloid proteins polymerizing into amyloid fibrils, or as immunoglobulin fragments that are subject to degradation as soon as they are excreted out of the tumor cell. In this paper, we review the occurrence of amyloid tumors in non-secretory multiple myeloma and, in a single case report, we confirm the existence of carbohydrate residues, including sialic acids and sulfated GAGs, in amyloid deposits.

Amyloid↗
PubMed2004

An unusual clinical phenotype of Avellino corneal dystrophy associated with an Arg124His beta iG-H3 mutation in an African-American woman.

PURPOSE: To describe the clinical features, histologic changes, and genetic analysis of Avellino corneal dystrophy in an African-American woman. DESIGN: Interventional case report. METHODS: A 79-year-old African-American woman with corneal deposits consistent with Avellino corneal dystrophy was studied with histologic and genetic analysis. RESULTS: The patient had multiple crumb-like opacities in the anterior stroma of both eyes. Deep to these lesions were numerous faint, stellate lattice lesions. Corneal scraping confirmed the presence of Masson trichrome and Congo red positive subepithelial deposits. Genetic analysis revealed a heterozygous CGC/CAC change in exon 4 of the beta iG-H3 gene, resulting in an arginine to histidine substitution at codon 124. CONCLUSIONS: This case reveals several novel findings, including surface changes resembling vortex dystrophy and large granular deposits protruding through the anterior corneal surface. This is the first case described in an African-American patient.

Black or African American↗
PubMed2005

Prevalence of Staphylococcus epidermidis strains with biofilm-forming ability in isolates from conjunctiva and facial skin.

PURPOSE: To compare the prevalence of biofilm-forming strains of Staphylococcus epidermidis in the conjunctival and facial skin microflora. DESIGN: Experimental study. METHODS: The prevalence of biofilm-forming ability of 10 S epidermidis strains obtained from the conjunctival sac of healthy volunteers was compared with 40 strains obtained from the facial skin of healthy volunteers. The ability to form biofilm was determined by the presence of the icaA gene, and the production of biofilm was examined by qualitative (Congo red agar [CRA]) and quantitative (microtiter plate) assays. Additionally, the prevalence of 36 S epidermidis strains obtained from the conjunctival sac of precataract patients to form biofilm was investigated. RESULTS: The icaA gene was detected in 60% of the isolates from the conjunctival sac of volunteers and 15% of those from the facial skin. Fifty percent of the isolates from the conjunctiva of volunteers and 5% from the facial skin were CRA positive. Biofilm production was significantly greater in isolates from the conjunctiva of volunteers. Of the nine pairs of isolates found in the same volunteers, six conjunctival sac isolates were positive for the icaA gene with biofilm-forming ability except one strain, whereas only one of the facial skin isolates was positive for the icaA gene and none exhibited biofilm-forming phenotype. Sixty-nine percent and 44% of the isolates from the conjunctival sac of precataract patients were positive for icaA gene and CRA test, respectively. CONCLUSIONS: The prevalence of biofilm-forming S epidermidis isolates is higher in the conjunctival sac than the facial skin.

Aged↗
PubMed2004

Tau aggregation is driven by a transition from random coil to beta sheet structure.

The abnormal aggregation of the microtubule associated protein tau into paired helical filaments (PHFs) is one the hallmarks of Alzheimer's disease. The soluble protein is one of the longest natively unfolded proteins, lacking significant amounts of secondary structure over a sequence of 441 amino acids in the longest isoform. Furthermore, the unfolded character is consistent with some notable features of the protein like stability towards heat and acid treatment. It is still unclear how these characteristics support the physiological function of binding to and stabilization of microtubules. We review here some recent studies on how an unfolded protein such as tau can adopt beta-structure, which then leads to the highly ordered morphology of the PHFs. The core sequence for both microtubule binding and PHF formation is the microtubule binding domain containing three or four repeats. This region alone is sufficient for PHF formation and mostly unfolded in the soluble state. A search for sequence motifs within this region crucial for PHF building revealed two hexapeptides in the second and the third repeat. Some of the genetically linked cases of FTDP-17 show missense mutations in or adjacent to these hexapeptide motifs. Proteins containing the P301L and the DeltaK280 mutations exhibit accelerated aggregation. The importance of the two hexapeptides stems from their capacity to undergo a conformational change from a random coil to a beta sheet structure. The increase of beta sheet structure is a typical feature of an amyloidogenic protein and is the basis of other characteristics like a decreased sensitivity towards proteolytic degradation and Congo red binding. PHFs aggregated in vitro and in vivo contain beta-sheet structure, as judged by circular dichroism (CD) spectroscopy, Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction.

Alzheimer Disease↗
PubMed2004

Cloning and characterization of two thermostable xylanases from an alkaliphilic Bacillus firmus.

Two genes encoding thermostable xylanases, named xyn10A and xyn11A, from an alkaliphilic Bacillus firmus were cloned and expressed in Escherichia coli. The E. coli harboring either gene showed clear zone with Congo red clearance assay on xylan plate. The Xyn10A and Xyn11A have molecular weights of 45 and 23kDa, respectively, and both show activities on xylan-zymogram. The xyn10A encodes 396 amino acid residues and is very similar to an alkaliphilic xylanase A from alkaliphilic Bacillus halodurans. The Xyn11A contains 210 amino acid residues and only one amino acid different from an endo-beta-1,4-xylanase from B. halodurans. From alignment of the amino acid sequences with other xylanases, Xyn10A and Xyn11A belong to family 10 and 11 glycosyl hydrolases, respectively. Both show activities over the pH range of 4-11 at 37 degrees C and over 80% activities at 70 degrees C. Interestingly both still retain over 70% activities after 16h preincubation at 62 degrees C.

Amino Acid Sequence↗
PubMed2005

Amyloid fibril formation by macrophage migration inhibitory factor.

We demonstrate herein that human macrophage migration inhibitory factor (MIF), a pro-inflammatory cytokine expressed in the brain and not previously considered to be amyloidogenic, forms amyloid fibrils similar to those derived from the disease associated amyloidogenic proteins beta-amyloid and alpha-synuclein. Acid denaturing conditions were found to readily induce MIF to undergo amyloid fibril formation. MIF aggregates to form amyloid-like structures with a morphology that is highly dependent on pH. The mechanism of MIF amyloid formation was probed by electron microscopy, turbidity, Thioflavin T binding, circular dichroism spectroscopy, and analytical ultracentrifugation. The fibrillar structures formed by MIF bind Congo red and exhibit the characteristic green birefringence under polarized light. These results are consistent with the notion that amyloid fibril formation is not an exclusive property of a select group of amyloidogenic proteins, and contribute to a better understanding of the factors which govern protein conformational changes and amyloid fibril formation in vivo.

Amyloid↗
PubMed2006

A transgenic rat with the human ATTR V30M: a novel tool for analyses of ATTR metabolisms.

Amyloidogenic transthyretin (ATTR) is the pathogenic protein of familial amyloidotic polyneuropathy (FAP). To establish a tool for analyses of ATTR metabolisms including after liver transplantations, we developed a transgenic rat model expressing human ATTR V30M and confirmed expressions of human ATTR V30M in various tissues. Mass spectrometry for purified TTR revealed that rat intrinsic TTR and human ATTR V30M formed tetramers. Congo red staining and immunohistochemistry revealed that nonfibrillar deposits of human ATTR V30M, but not amyloid deposits, were detected in the gastrointestinal tracts of the transgenic rats. At 24h after liver transplantation, serum human ATTR V30M levels in transgenic rats that received livers from normal rats became lower than detectable levels. These results thus suggest that this transgenic rat may be a useful animal model which analyzes the metabolism of human ATTR V30M including liver transplantation studies.

Amyloid Neuropathies, Familial↗
PubMed2006

Towards developing surface eroding poly(alpha-hydroxy acids).

We have prepared a library of biodegradable polyesters derived from poly(alpha-hydroxy acids) (PHAs) that appear to primarily exhibit surface erosion behavior. This was achieved by increasing the hydrophobicity of the polymers in two distinct steps, namely: macromer formation and a coupling step. In the first step, macromerdiols (MDs) with varying lipophilicities were prepared by polymerization of L-lactide or mixture of L-lactide and glycolide (3/1 by mole) to various lengths (n = 10, 20, 30, and 40) using alkanediols of increasing C-chain length (C6, C8, and C12) as initiators in the presence of Tin(II) catalyst. In the second step, the macromer diols were linked together with diacid dichlorides of varying C-chain lengths (C6, C8, C10, and C12) to yield polyesters ranging in molecular weight (Mw) from 20 to 130 KDa and polydispersity of 1.5-6. These polyesters exhibited different thermal behavior from pure PHAs that can be tuned by changing the initiator core, the lactide/glycolide chain length, and diacid dichloride type. In addition, all these polymers showed solubility in tetrahydrofuran unlike poly(L-lactic acid) (PLLA) and poly(lactide-co-glycolide) (PLGA). In contrast to PLLA and PLGA, the degradation behavior of these novel polyesters exhibited linear profiles consistent with a surface erosion behavior. Release studies using Congo red as a model drug from microspheres prepared from these polyesters showed linear release profiles with correlation constants of least-square fits approaching a value of unity. Degradable polyesters with tunable thermal and degradation behavior may find applications in drug delivery and tissue engineering, where control over these parameters is critical to ensure predictable outcomes.

Absorbable Implants↗
PubMed2004

Evaluation of Argentinean white rot fungi for their ability to produce lignin-modifying enzymes and decolorize industrial dyes.

The decolorizing capacity of 26 white rot fungi from Argentina was investigated. Extracellular production of ligninolytic enzymes by mycelium growing on solid malt extract/glucose medium supplemented with different dyes (Malachite Green, Azure B, Poly R-478, Anthraquinone Blue, Congo Red and Xylidine), dye decolorization and the relationship between these two processes were studied. Only ten strains decolorized all the dyes, all ten strains produced laccase, lignin peroxidase and manganese peroxidase on solid medium. However, six of the strains could not decolorize any of the dyes; all six strains tested negative for lignin peroxidase, and produced less than 0.05 U/g agar of manganese peroxidase. Comparing the isolates with the well-known dye-degrader Phanerochaete chrysosporium, a new fungus was identified: Coriolus versicolor f. antarcticus, potentially a candidate for use in biodecoloration processes. Eighteen day-old cultures of this fungus were able to decolorize in an hour 28%, 30%, 43%, 88% and 98% of Xylidine (24 mg/l), Poly R-478 (75 mg/l), Remazol Brilliant Blue R (9 mg/l), Malachite Green (6 mg/l) and Indigo Carmine (23 mg/l), respectively. Laccase activity was 0.13 U/ml, but neither lignin peroxidase nor manganese peroxidase were detected in the extracellular fluids for that day of incubation.

Argentina↗
PubMed2004

Decolorization of synthetic dyes by solid state cultures of Lentinula (Lentinus) edodes producing manganese peroxidase as the main ligninolytic enzyme.

The ability of the white-rot fungus Lentinula (Lentinus) edodes to decolorize several synthetic dyes was investigated using solid state cultures with corn cob as substrate. Cultures, containing amido black, congo red, trypan blue, methyl green, remazol brilliant blue R, methyl violet, ethyl violet and Poly R478 at 200 ppm, were completely decolorized after 18 days of incubation. Partial decolorization was observed in the cultures containing 200 ppm of brilliant cresyl blue and methylene blue. High manganese peroxidase activity (2600 U/g substrate), but very low lignin peroxidase (<10 U/g substrate) and laccase (<16 U/g substrate) activities were detected in the cultures. In vitro, the dye decolorization was markedly decreased by the absence of manganic ions and H2O2. These data suggest that manganese peroxidase appear to be the main responsible for the capability of L. edodes to decolorize synthetic dyes.

Analysis of Variance↗
PubMed2005

Cloning, sequencing and expression of the xylanase gene from a Bacillus subtilis strain B10 in Escherichia coli.

Bacillus subtilis strain B10 was isolated for degumming of ramie blast fibers, and a fragment of 642-bp was amplified from chromosomal DNA by using primers directed against the sequence of Bacillus subtilis xylanase gene given in GenBank. The positive clones were screened on the selected LB agar plates supplemented with xylan by Congo-red staining method. The recombinant plasmid from one positive clone was used for further analysis and DNA sequencing. The gene sequence is different from the reported xylanase gene sequence in sites of two base pairs. The recombinant plasmid was expressed in Escherichia coli, and xylanase activity was measured. The xylanase distribution in extracellular, intracellular and periplasmic fractions were about 22.4%, 28.0% and 49.6%, respectively. The xylanase had optimal activity at pH 6.0 and 50 degrees C.

Amino Acid Sequence↗
PubMed2006

A beta-D-glucan isolated from the fruiting bodies of Hericium erinaceus and its aqueous conformation.

HEP3, a beta-D-glucan slightly soluble in water, was isolated from the alkaline extract of the fruiting bodies of Hericium erinaceus. Its chemical structure was investigated by methylation analysis, periodate oxidation, Smith degradation and by IR and NMR spectroscopy. It was shown to have a main chain composed of beta-(1-->3)-linked D-glucopyranosyl residues, with single unit glucosyl branches attached to O-6 of every third backbone residue. Viscometry and Congo red reaction indicated that HEP3 has a highly ordered hydrogen-bond dependent conformation in aqueous solution, which collapses in strong alkaline solution.

Carbohydrate Conformation↗
PubMed2004

Effect of dye compounds on the adsorption of atrazine by natural sediment.

The overall objective of this research is to investigate competitive adsorption between atrazine (AT) and dye compounds in the natural aquatic sediment. The sorbent was sediment obtained from Guanting Reservoir (Beijing, China), which contained 25% sand, 67% silt, 8% clay, and 2.06% organic carbon. Batch adsorption experiments were conducted at various Ca2+ concentration, pH levels, temperatures, and introducing conditions of dye compounds. Compared with the dye-free system, both of dyes including Congo red (CR) and methylene blue (MB) reduce the adsorption of atrazine over the range of dye concentrations examined, with the adsorption percentage of atrazine decreasing about 14-30%. And the competition between AT and MB is much stronger than that between AT and CR. The adsorption experimental data points have been fitted to the Freundlich equation in order to calculate the adsorption capacities (Kf) of the samples; Kf values range from 1.669 micromol/kg for the MB-AT sample up to 3.738 micromol/kg for the AT-alone sample. By contrast with the single-solute adsorption isotherm, both simultaneous adsorption and dye preloading inhibit the adsorption of atrazine. As for AT preloading, the impacts of CR and MB are different on the desorption of atrazine. As compared to the atrazine desorption without dye compounds, a certain amounts of atrazine molecules are replaced by MB in AT preloading system, while in CR solution AT is adsorbed strongly on the sediment and could not be replaced by CR. The result suggests that micropore constriction by CR reduces the desorption rate of atrazine.

Adsorption↗
PubMed2004

Characterization of beta amyloid assemblies in drusen: the deposits associated with aging and age-related macular degeneration.

PURPOSE: Recent studies strongly suggest that drusen, the extracellular deposits associated with age-related macular degeneration (AMD), are a manifestation of local inflammatory events. New evidence indicates that substructural elements within drusen contain activated complement components as well as amyloid beta (Abeta), a major pro-inflammatory component of Alzheimer's disease plaques. We characterized the ultrastructural organization and histochemical staining properties of these Abeta-containing elements in order to further assess their significance in drusen formation and AMD pathogenesis. METHODS: We used differential interference contrast optics, laser scanning confocal immunofluorescence, and immunogold electron microscopy to characterize the structural properties and molecular composition of Abeta-containing elements in drusen. We obtained estimates of their frequency from montages of electron micrographs gathered from 152 human donor eyes ranging from 9 to 91 years of age. RESULTS: Spherical Abeta-containing elements, which are typically organized as concentric ring-like structures, are common substructural components of drusen. They stain with thioflavin T, but are not stained by Congo red; nor do they bind cationic, lipophilic, or nucleic acid-binding fluorescent dyes. Ultrastructurally, they are composed of a central core, one or more concentric inner rings with intervening electron lucent layers, and an electron dense outer shell. Immunogold labeling indicates that most Abeta immunoreactivity is associated with the outer layers that consist of densely-packed spherical subunits. No longitudinally-oriented fibril arrays, characteristic of aggregated amyloid fibrils in the brain, are evident. Other prominent drusen-associated proteins including the terminal complement complex C5b-9, vitronectin, apolipoprotein E, serum amyloid P component, and ubiquitin are excluded from the spheres.Conclusions. These structures embedded in drusen appear to represent a new type of macromolecular assembly that contains Abeta as well as activated complement components. The presence of Abeta in these extracellular deposits is an additional indication that some of the pathogenic pathways that give rise to drusen and AMD may be shared with other neurodegenerative diseases characterized by misfolded protein deposition and aggregation.

Adolescent↗
PubMed2004

Transgenic mice overexpressing amyloid beta protein are an incomplete model of Alzheimer disease.

We compared lesions in elderly transgenic (tg) mice carrying the Swedish double mutation KM670/671NL with lesions in Alzheimer disease (AD) by histochemical and immunohistochemical techniques. Highly similar staining for beta-amyloid protein (Abeta) was observed in AD and the mouse models. The abundant amyloid deposits in tg mice were in a consolidated state as revealed by strong Congo red birefringence. In both tg mice and AD, amyloid deposits were ApoE-positive and were surrounded by activated astrocytes. However, Bielschowsky silver staining and immunostaining with tau antibodies revealed no neurofibrillary tangles (NFTs) in the mice as opposed to abundant NFTs in AD. The microglial pattern was also distinctly different. Tg mice had only weakly activated microglia, which expressed low levels of the complement receptor CD11b. They were gathered around the periphery of the deposits. In contrast, AD lesions had strongly activated microglia, which expressed high levels of CD11b. They were associated with the plaque core. Immunostaining for complement proteins was weak in tg mice but very strong in AD deposits. We conclude that the weak inflammatory response and absence of NFTs indicate that tg mice are only a limited model of AD. Therapeutic strategies for the treatment of AD based on tg mouse models that overexpress Abeta may be limited in their application.

Age Factors↗
PubMed2005

Chiral bias of amyloid fibrils revealed by the twisted conformation of Thioflavin T: an induced circular dichroism/DFT study.

Since it was implicated in a number of neurodegenerative conditions, such as Alzheimer disease, formation of beta-sheet-rich protein fibrils (amyloids) has been drawing a lot of attention. One of elusive aspects of amyloidogenesis concerns the mechanisms of specific binding of molecules such as Congo red, or Thioflavin T by amyloid fibrils. A comprehensive understanding of these docking interactions is needed, however, for the sake of furthering biochemical studies and developing molecular, pharmacological strategies preventing proliferation of amyloids in vivo. Through the application of circular dichroism, here we show that upon binding to insulin fibrils, a twisted conformation is enforced in molecules of Thioflavin T, manifested in a strong negative Cotton effect around 450 nm, which is supported by density functional theory-based calculations. This finding may lead to circular dichroism of Thioflavin T becoming a new diagnostic technique for protein fibrils, complementary to fluorescence spectroscopy.

Amyloid beta-Peptides↗