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PubMed1986

Secondary (AA) amyloidosis in cystic fibrosis. A report of three cases.

The authors report the pathologic features of three cases of amyloidosis associated with cystic fibrosis. Renal biopsy led to the diagnosis (case 1) or suspicion (case 2) of amyloidosis in patients who were 23 and 21 years old, respectively. The third patient died at age 22 years, and amyloidosis was not discovered until autopsy. Immunohistochemical staining and potassium-permanganate pretreatment of histologic sections in all three cases provided evidence that the amyloid seen in these patients is of the secondary (AA) type. Congo red staining in each case and electron microscopy in case 1 confirmed the initial diagnosis of amyloidosis. A markedly elevated serum amyloid A protein (160 micrograms/mL; normal less than 1 microgram/mL) in case 1 indicated the presence of large quantities of the precursor protein from which the AA fibrils of secondary amyloid are derived. The kidneys, spleen, and liver contained amyloid deposits in autopsy material from all three cases. Involvement of other organs by amyloid was variable. Review of autopsy material in Boston from 23 additional cystic fibrosis patients with long-term survival did not reveal any evidence of amyloidosis. It appears that secondary amyloidosis is emerging as a significant, although rare, complication of cystic fibrosis as greater numbers of these patients survive into adulthood.

Adult↗
PubMed2005

Biofilm formation, cellulose production, and curli biosynthesis by Salmonella originating from produce, animal, and clinical sources.

The ability of 71 strains of Salmonella enterica originating from produce, meat, or clinical sources to form biofilms was investigated. A crystal violet binding assay demonstrated no significant differences in biofilm formation by isolates from any source when tested in any of the following three media: Luria-Bertani broth supplemented with 2% glucose, tryptic soy broth (TSB), or 1/20th-strength TSB. Incubation was overnight at 30 degrees C under static conditions. Curli production and cellulose production were monitored by assessing morphotypes on Luria-Bertani agar without salt containing Congo red and by assessing fluorescence on Luria-Bertani agar containing calcofluor, respectively. One hundred percent of the clinical isolates exhibited curli biosynthesis, and 73% demonstrated cellulose production. All meat-related isolates formed curli, and 84% produced cellulose. A total of 80% of produce-related isolates produced curli, but only 52% produced cellulose. Crystal violet binding was not statistically different between isolates representing the three morphotypes when grown in TSB; however, significant differences were observed when strains were cultured in the two other media tested. These data demonstrate that the ability to form biofilms is not dependent on the source of the test isolate and suggest a relationship between crystal violet binding and morphotype, with curli- and cellulose-deficient isolates being least effective in biofilm formation.

Bacterial Proteins↗
PubMed2004

Kinetic analysis of beta-amyloid fibril elongation.

We used surface plasmon resonance biosensors to evaluate the kinetics associated with the initial events of beta-amyloid (Abeta) fibril elongation. Fibrils were immobilized on the sensor chip surface and extended by exposure to soluble Abeta(1-40) peptide. The fibril surfaces bound Congo red, a marker for beta sheet structures, and exhibited a slow linear background decay that is consistent with fibril depolymerization. Sonicated fibrils supported elongation better than unsonicated fibrils, which is consistent with fibril extension reactions. The kinetic data revealed that peptide association and dissociation occurred in multiple steps. Kinetic rate constants for fibril extension were determined by globally fitting the response data with a three-step polymerization model. In the first step, the soluble peptide binds to the growing fibril tip in a readily reversible reaction. The subsequent steps likely allow bound peptide to be stabilized into the growing fiber through postbinding transitional events. Using a mutant peptide, F19P Abeta(1-40), we illustrate how the biosensor assay can be used to probe structure/function relationships of fibril elongation.

Amyloid beta-Peptides↗
PubMed1999

Role of the mitogen-activated protein kinase Hog1p in morphogenesis and virulence of Candida albicans.

The relevance of the mitogen-activated protein (MAP) kinase Hog1p in Candida albicans was addressed through the characterization of C. albicans strains without a functional HOG1 gene. Analysis of the phenotype of hog1 mutants under osmostressing conditions revealed that this mutant displays a set of morphological alterations as the result of a failure to complete the final stages of cytokinesis, with parallel defects in the budding pattern. Even under permissive conditions, hog1 mutants displayed a different susceptibility to some compounds such as nikkomycin Z or Congo red, which interfere with cell wall functionality. In addition, the hog1 mutant displayed a colony morphology different from that of the wild-type strain on some media which promote morphological transitions in C. albicans. We show that C. albicans hog1 mutants are derepressed in the serum-induced hyphal formation and, consistently with this behavior, that HOG1 overexpression in Saccharomyces cerevisiae represses the pseudodimorphic transition. Most interestingly, deletion of HOG1 resulted in a drastic increase in the mean survival time of systemically infected mice, supporting a role for this MAP kinase pathway in virulence of pathogenic fungi. This finding has potential implications in antifungal therapy.

Animals↗
PubMedDate not supplied

Primary macular amyloidosis: an ultrastructural approach to diagnosis.

Seven cases of primary macular amyloidosis were studied on skin biopsies. The Congo red stain was positive only in three cases, whereas the ultrastructural observation allowed for the detection of amyloid deposits in all biopsies. Fibrillary degeneration of basal keratynocytes was occasionally observed, and regressive changes of keratynocytes and dermal nerve bundles presumably related to the intensity of the scratch trauma were detected in one case. In six biopsies mast cell profiles exhibiting various degrees of degranulation were detected in the dermis. Melanosome aggregates were also observed consistently in dermal macrophages and occasionally in Schwann cells. A variable degree of structural alteration was observed in dermal unmyelinated nerve fibers. Even if the intimate mechanism of amyloid deposition was not explained by the ultrastructural study, this approach is a useful instrument in the differential diagnosis of cutaneous macular hyperpigmented lesions.

Aged↗
PubMed2006

Biofilm-forming ability profiling of Staphylococcus aureus and Staphylococcus epidermidis mastitis isolates.

Biofilm-forming ability has been increasingly recognized as an important virulence factor in Staphylococci, facilitating their persistence in the host, evading its defences and allowing bacterial survival at high antimicrobial concentrations. Staphylococcus aureus remains a major pathogen of chronic mastitis, but in the last years Staphylococcus epidermidis has emerged as a relevant mastitis pathogen. The present work aimed at the evaluation of the biofilm-forming ability of Staphylococci field isolates from bovine subclinical mastitis and at the development of a fluorescent in situ hybridisation (FISH) protocol that would allow the direct observation of biofilm formation in milk samples. The analysis of phenotypic expression in Congo Red Agar (CRA) and by FISH, showed that 37.5% of the S. aureus isolates produced biofilm, while by optical density measurement only 18.75% isolates revealed this phenotype. The results showed a fair agreement according to the kappa coefficient test (kappa = 0.259). Regarding S. epidermidis mastitis isolates, 37.5% revealed the ability to produce biofilm, but only four isolates were positive by all methods. This agreement was moderate (kappa = 0.467). The application of FISH to artificially contaminated milk samples allowed the direct observation of biofilm production by 37.5% isolates, showing total agreement with the CRA results. This method better mimics the in vivo conditions, especially in terms of the presence of calcium and iron, which in high concentrations, respectively, are known to inhibit or induce biofilm production.

Animals↗
PubMed1995

Dialysis arthropathy: outcome after renal transplantation.

PURPOSE: Patients treated by long-term maintenance hemodialysis frequently develop a form of chronic arthropathy that is strongly associated with beta 2-microglobulin amyloid deposition and related, at least in part, to beta 2-microglobulin retention. Successful renal transplantation is followed by a rapid fall in serum beta 2-microglobulin levels and might allow dissolution of amyloid deposits. The purpose of this work was to investigate the effects of renal transplantation on dialysis arthropathy. PATIENTS AND METHODS: Fourteen renal transplant recipients were selected on the basis of previous hemodialysis treatment for at least 10 years (mean 16) and a history of chronic joint pain prior to transplantation. They all received 10 to 17.5 mg/d of prednisone. Posttransplant rheumatologic manifestations were studied prospectively and compared to pretransplant rheumatologic manifestations recorded in medical charts and reported during patient interviews. Pretransplant and posttransplant articular roentgenograms were separately analyzed by three observers who were blinded to timing of the films. Beta 2-microglobulin amyloid was identified by Congo red staining and immunohistology. RESULTS: After a mean posttransplant interval of 54 months (range 12 to 121), the articular condition was improved in 10 patients, unchanged in 1, and worsened in 3, according to patients' assessments. The number of painful joints decreased significantly (P < 0.05) as compared to the pretransplant period. However, the number and size of subchondral bone erosions remained unchanged, destructive arthropathies generally worsened, and articular beta 2-microglobulin amyloid deposits were identified in 2 patients, 2 and 10 years after renal transplantation, respectively. CONCLUSION: Renal transplantation appeared to arrest progression of beta 2-microglobulin amyloid in dialysis patients, but it neither led to dissolution of deposits nor prevented progression of destructive arthropathies. Most articular symptoms were improved, probably as a result of corticosteroid therapy.

Adult↗
PubMed2005

Comparative use of bacterial, algal and protozoan tests to study toxicity of azo- and anthraquinone dyes.

Toxicity of two azo dyes (Reactive Orange 16 (RO16); Congo Red (CR)) and two anthraquinone dyes (Remazol Brilliant Blue R (RBBR); Disperse Blue 3 (DB3)) were compared using bacterium Vibrio fischeri, microalga Selenastrum capricornutum and ciliate Tetrahymena pyriformis. The following respective endpoints were involved: acute toxicity measured as bacterial luminescence inhibition, algal growth inhibition, and the effects on the protozoa including viability, growth inhibition, grazing effect and morphometric effects. In addition, mutagenicity of the dyes was determined using Ames test with bacterium Salmonella typhimurium His(-). DB3 dye was the most toxic of all dyes in the bacterial, algal and protozoan tests. In contrast to other dyes, DB3 exhibited mutagenic effects after metabolic activation in vitro in all S. typhimurium strains used. Of the methods applied, the algal test was the most sensitive to evaluate toxicity of the dyes tested.

Aliivibrio fischeri↗
PubMed1999

The sulfate moieties of glycosaminoglycans are critical for the enhancement of beta-amyloid protein fibril formation.

Our previous studies have demonstrated that perlecan and perlecan-derived glycosaminoglycans (GAGs) not only bind beta-amyloid protein (Abeta) 1-40 and 1-42, but are also potent enhancers of Abeta fibril formation and stabilize amyloid fibrils once formed. However, it was not determined which moieties in perlecan heparan sulfate GAG chains may be responsible for the observed effects and whether other GAGs were also capable of a similar enhancement of Abeta fibril formation as observed with perlecan GAGs. In the present study, thioflavin T fluorometry (over a 1-week period) was used to extend our previous studies and to test the hypothesis that the sulfate moiety is critical for the enhancing effects of heparin/heparan sulfate GAGs on Abeta 1-40 fibrillogenesis. This hypothesis was confirmed when removal of all sulfates from heparin (i.e., completely desulfated N-acetylated heparin) led to a complete loss in the enhancement of Abeta fibrillogenesis as demonstrated in both thioflavin T fluorometry and Congo red staining studies. On the other hand, removal of O-sulfate from heparin (i.e., completely desulfated N-sulfated heparin), and to a lesser extent N-sulfate (i.e., N-desulfated N-acetylated heparin), resulted in only a partial loss of the enhancement of Abeta 1-40 fibril formation. These studies indicate that the sulfate moieties of GAGs are critical for enhancement of Abeta amyloid fibril formation. In addition, other sulfated molecules such as chondroitin-4-sulfate, dermatan sulfate, dextran sulfate, and pentosan polysulfate all significantly enhanced (greater than twofold by 3 days) Abeta amyloid fibril formation. These latter findings indicate that deposition and accumulation of other GAGs at sites of Abeta amyloid deposition in Alzheimer's disease brain may also participate in the enhancement of Abeta amyloidosis.

Alzheimer Disease↗
PubMed2004

Amyloid fibril formation by a partially structured intermediate state of alpha-chymotrypsin.

Here we investigated the effects of 2,2,2-trifluoroethanol (TFE) on the structure of alpha-chymotrypsin. The protein aggregates maximally in 35% (v/v) TFE. Congo red and thioflavin-T binding experiments suggest that the aggregates induced by TFE have amyloid-like properties, and transmission electron microscopy data show that these aggregates have a fibrilar morphology. Fluorescence, circular dichroism, anilino-8-napthalene sulfonate binding, and Fourier-transformed infrared spectroscopy data suggest that formation of a partially structured intermediate state precedes the onset of the aggregation process. The native beta-barrel structure of alpha-chymotrypsin appears to be disrupted in the partially structured intermediate state in favour of a non-native extended beta-sheet conformation with exposed hydrophobic surfaces. The protein becomes "sticky" under these conditions and aggregates into amyloid-like structures. The data support the hypothesis that amyloid formation involves the ordered self-assembly of partially folded species that are critical soluble precursors of fibrilar aggregates.

Amyloid↗
PubMed2006

Detection of biofilm formation among the clinical isolates of Staphylococci: an evaluation of three different screening methods.

PURPOSE: The purpose of this study was to evaluate three methods for detection of biofilm formation in staphylococci. METHODS: For detection of biofilm formation, 152 clinical isolates of Staphylococcus spp. were screened by tissue culture plate (TCP), Tube method (TM) and Congo red agar (CRA) method. RESULTS: Of the 152 Staphylococcus spp. 88(57.8%) displayed a biofilm-positive phenotype under the optimized conditions in the TCP method and strains were further classified as high 22 (14.47 %) and moderate 60 (39.4 %) while in 70 (46.0 %) isolates weak or no biofilm was detected. Though TM correlated well with the TCP test for 18 (11.8 %) strongly biofilm producing strains, weak producers were difficult to discriminate from biofilm negative isolates. Screening on CRA does not correlate well with either of the two methods for detecting biofilm formation in staphylococci. CONCLUSION: The TCP method was found to be most sensitive, accurate and reproducible screening method for detection of biofilm formation by staphylococci and has the advantage of being a quantitative model to study the adherence of staphylococci on biomedical devices.

Agar↗
PubMed2004

Genotypic and phenotypic screening of high and low virulence Staphylococcus aureus isolates from rabbits for biofilm formation and MSCRAMMs.

At rabbit flock level, two types of Staphylococcus aureus infections can be distinguished. In the first type, caused by low virulence strains, the infection remains limited to a small number of animals. The second type of infection is caused by the high virulence strains, which spread throughout the rabbitry. The pathogenetic capacity of a particular S. aureus strain is attributed to a combination of extracellular factors and invasive properties such as adherence and biofilm formation. Twenty eight high virulence and 34 low virulence S. aureus isolates recovered from rabbits between 1998 and 2003 were used to study slime production on Congo red Agar (CRA) and prevalence of bap, icaA and icaD associated with biofilm formation. Furthermore these strains were screened for the presence of bbp, clfA, clfB, cna, ebpS, eno, fnbA, fnbB and fib encoding microbial surface components recognizing adhesive matrix molecules (MSCRAMMs). The presence of icaA and icaD was not correlated with slime production on CRA. Bap was absent in all strains. All rabbit S. aureus strains harboured clfA and clfB. The prevalences of ebpS, eno, fnbA and fib did not reveal striking differences between high and low virulence strains. FnbB prevalence in high virulence isolates was lower than in low virulence isolates and cna was absent in high virulence strains. It was remarkable that only high virulence strains were positive for bbp. Further research is necessary to elucidate the significance of bbp in the pathogenesis of high virulence strains.

Adhesins, Bacterial↗
PubMed1968

The characterization of soluble amyloid prepared in water.

Amyloid was extracted from the spleen of a patient with primary amyloidosis by homogenizing it at high speed with water after preliminary treatments, first to remove proteins soluble in saline, and then to remove salts. The extracts containing amyloid appeared to be clear at concentrations up to 6 mg/ml of protein. The material gave little sediment on being centrifuged up to 20,000 g for 1 hr, but the protein was sedimented at 100,000 g in 1 hr. The amyloid could be precipitated from the extracts by addition of NaCl to 0.0075 mole/liter or of CaCl(2) to 0.0025 mole/liter. The protein-bound Congo red formed a red precipitate and this property was used to estimate recovery and purity of amyloid during extraction. On electronmicroscopy the isolated amyloid proved to be morphologically pure. It existed either as single filaments measuring 60-80 A in diameter or as large aggregates of these filaments.Freshly isolated amyloid in water sedimented as a single homogeneous peak with an s degrees (20,[unk]) of about 45-50S. On standing, the solution became cloudy and more rapidly sedimenting components appeared. On electrophoresis the material migrated as a homogeneous peak towards the anode. The protein had an amino acid composition different from that of all known serum proteins. It was rich in acidic amino acids and had little cysteine and methionine and no hydroxyproline. The total content of carbohydrate was less than 2%.

Amino Acids↗
PubMed1996

Attempts to find phenotypic markers of the virulence plasmid of Rhodococcus equi.

Four isolates of Rhodococcus equi, from pneumonic foals, and containing the 85 kb virulence plasmid, a porcine isolate containing an 80 kb plasmid, and their plasmid cured derivatives, were examined for 239 phenotypic properties in an attempt to find characters other than the virulence-associated protein (VapA) which might be encoded by the virulence plasmid in organisms grown at 37 degrees C. Tests chosen included those which have previously given variable results for R. equi isolates, since such variability might be attributed to plasmid curing, and characteristics which have been described as properties of plasmids of Rhodococcus species other than R. equi. Tests included cadmium resistance, Congo red binding, resistance to 26 antibiotics, conventional clinical microbiological tests, utilization of 95 different carbon sources, enzymatic activities in API ZYM, fluorogenic assays for exo- and endopeptidase, glycosidase activities, and testosterone degradation. Apart from production of VapA by foal isolates, no phenotypic property was identified in the plasmid-positive isolates. Phenotypic characteristics of R. equi that have not been described before, and might be useful in identification were: metabolism of N-acetyl-beta D-glucopyranoside, alpha- and beta-hydroxybutyric, alpha-ketobutyric and N-acetyl-glutamic acids, of methylpyruvate, heptanoate, nonanoate and stearate esters; exopeptidase activity against alanine-alanine-tyrosine, alanine-phenylalanine-lysine, glycine-arginine, lysine-alanine, and valine-glycine-alanine; endopeptidase activity against arginine and methionine; and hydrolysis of bis-phosphate ester.

Amino Acids↗
PubMed2002

Regulation of yeast protein kinase C activity by interaction with the small GTPase Rho1p through its amino-terminal HR1 domain.

Protein kinase C from Saccharomyces cerevisiae (Pkc1p) constitutes a prototypic member of the protein kinase C superfamily, as it shares all the conserved regions scattered among the isoenzymes of higher eukaryotes. The functional significance of some of the conserved domains in the yeast enzyme has not yet been investigated. We examined strains carrying a partial deletion in the amino-terminal region of the enzyme, which is homologous to the HR1 of the protein kinase C-related kinases. This strain was sensitive to the presence of caffeine, Calcofluor white and Congo red, all drugs known to affect mutants defective in the signal transduction pathway ensuring cellular integrity in which Pkc1p is a central component. Isolation of a single point mutation in HR1A, which shares the sensitivity to the drugs mentioned, confirmed the importance of this region for proper regulation of protein kinase C activity in vivo. Two-hybrid analysis provided evidence for an interaction of the small GTPase Rho1p with the HR1A region, in addition to the reported interaction of this protein with the C1 region of Pkc1p. MAP kinase phosphorylation assays indicate that this Rho1p-Pkc1p/HR1A interaction does not result in an activation of the kinase cascade. The intragenic lethality of mutants affected in both HR1A and the C1 domain reported in this work implies an essential role for Rho1p-Pkc1p interaction in yeast.

Amino Acid Sequence↗
PubMed1990

Microscopy of acid transport at the gastric surface in vivo.

In vivo microscopy of the gastric surface, and pH-sensitive dyes, were used to study the movement of acid formed in the gastric crypts across the mucus layer adherent to the gastric surface and into the lumen. Rats were anaesthetized and the stomach gently exteriorized. When the pH-sensitive dye Congo red was applied luminally to stain the gel, predominantly red spots (pH greater than 5) and occasional blue spots (pH less than 3), located above the outlets of the crypts, were observed in spontaneously-secreting mucosae. Maximal stimulation of acid secretion (pentagastrin, 40 micrograms kg-1 h-1) resulted in the appearance only of blue spots, but the pH in the mucus gel between the crypts remained more alkaline, as indicated by pink staining. The fluorescence dye acridine orange was injected intravenously to an estimated blood concentration of 10(-5)M in another type of experiment. This dye is concentrated and secreted by the parietal cells. Pronounced fluorescence was observed within spots of the gastric surface corresponding to the outlets of the gastric crypts, but no fluorescence was detected outside these areas. The results obtained with both dyes strongly suggest that acid (and pepsin) is transported across the mucus gel only at restricted sites.

Acridine Orange↗
PubMed2007

Evidence for fibril-like structure in bovine casein micelles.

The addition of Congo red (CR) dye to diluted raw skim milk resulted in a red shift indicative of the presence of fibril-like structures. Thioflavin T (ThT) is another dye that very specifically binds to protein fibrils, and when added to undiluted raw skim milk, the classic 485 nm fluorescence peak of a ThT-fibril complex was observed. Repeating these experiments with various raw milk components showed that the CR red shift and ThT fluorescence peak were due to the presence of casein micelles, and to a lesser extent, sodium caseinate. Fluorescent peaks were also observed when ThT was added to solutions of purified alpha(S)- and kappa-casein, but not beta-casein, in 0.5 M HEPES buffer (pH = 6.8). The addition of 25 mM Ca(2+) had no effect on beta-casein fluorescence, and significantly reduced the kappacasein peak. However, adding 25 mM Ca(2+) to alpha(S)-casein produced a turbid solution and a 6-fold increase in fluorescence, indicating that the aggregates formed contain fibril-like structure. Casein micelle images obtained by transmission electron microscopy showed the presence of short (7 to 10 nm) fibers cross-linked by dense aggregate junction zones. The observed fibers closely resemble protofibrils, intermediate structures that are observed during the formation of amyloid fibrils.

Animals↗
PubMed2005

Identification of neurite outgrowth active sites on the laminin alpha4 chain G domain.

The laminin alpha4 chain is widely distributed in various mesodermal tissues, including the perineurium of peripheral nerves, dorsal root ganglion (DRG), skeletal muscle, and capillaries, and plays important roles in synaptic specialization at the neuromuscular junction and in microvascular formation. The C-terminal globular domain (G domain) of the laminin alpha4 chain was previously found to be critical for heparin binding and cell attachment activity. Here, we focused on neurite outgrowth activity of the laminin alpha4 chain G domain. We found that the recombinant alpha4 chain G domain protein (rec-alpha4G) promoted neurite outgrowth of rat pheochromocytoma PC12 cells. When 114 overlapping synthetic peptides that covered the entire G domain were tested for neurite outgrowth activity, nine peptides were active, but the 105 remaining peptides did not exhibit activity. Three of the nine active peptides, A4G6 (LAIKNDNLVYVY), A4G20 (DVISLYNFKHIY), and A4G107 (VIRDSNVVQLDV), strongly promoted neurite outgrowth of PC12 cells. A4G107 was found to form amyloid-like fibrils in Congo red, X-ray, and electron microscopy analyses. We also synthesized cyclic peptides to evaluate their conformational requirements. Cyclic peptide A4G82X (cyc-A4G82X;TLFLAHGRLVFX, where X is norleucine) significantly enhanced neurite outgrowth activity, but the rest of the cyclic peptides eliminated the activity. The A4G82 sequence is located on the loop region, suggesting that the activity of A4G82 is required for a loop conformation. These peptides also exhibited neurite outgrowth activity with dorsal root ganglion (DRG) explants and with DRG cells from E14.5 mouse embryos, indicating that they are active in both neuronal cell lines and native neuronal cells. Taken together, the data suggest that the peptides from the laminin alpha4 chain G domain promote neurite outgrowth activity via a specific conformation.

Amino Acid Sequence↗