SEARCH · Search PubMed

Results for “CONGO RED”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

SourceResearch connectionFrom yearThrough year

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,027 records · Page 57Linked to original sources

PubMed2000

Salmonella enteritidis fimbriae displaying a heterologous epitope reveal a uniquely flexible structure and assembly mechanism.

Two distinct Salmonella fimbrins, AgfA and SefA, comprising thin aggregative fimbriae SEF17 and SEF14, respectively, were each genetically engineered to carry PT3, an alpha-helical 16-amino acid Leishmania T-cell epitope derived from the metalloprotease gp63. To identify regions within AgfA and SefA fimbrins amenable to replacement with this epitope, PCR-generated chimeric fimbrin genes were constructed and used to replace the native chromosomal agfA and sefA genes in Salmonella enteritidis. Immunoblot analysis using anti-SEF17 and anti-PT3 sera demonstrated that all ten AgfA chimeric fimbrin proteins were expressed by S. enteritidis under normal growth conditions. Immunoelectron microscopy confirmed that eight of the AgfA::PT3 proteins were effectively assembled into cell surface-exposed fimbriae. The PT3 replacements in AgfA altered Congo red (CR) binding, cell-cell adhesion and cell surface properties of S. enteritidis to varying degrees. However, these chimeric fimbriae were still highly stable, being resistant to proteinase K digestion and requiring harsh formic acid treatment for depolymerization. In marked contrast to AgfA, none of the chimeric SefA proteins were expressed or assembled into fimbriae. Since each PT3 replacement constituted over 10% of the AgfA amino acid sequence and all ten replacements collectively represented greater than 75% of the entire AgfA primary sequence, the ability of AgfA to accept large sequence substitutions and still assemble into fibers is unique among fimbriae and other structural proteins. This structural flexibility may be related to the novel fivefold repeating sequence of AgfA and its recently proposed structure Proper formation of chimeric fimbrial fibers suggests an unusual assembly mechanism for thin aggregative fimbriae which tolerates aberrant structures. This study opens a range of possibilities for Salmonella thin aggregative fimbriae as a carrier of heterologous epitopes and as an experimental model for studies of protein structure.

Amino Acid Sequence↗

PubMed1995

Interstitial amyloid deposits in the pituitary gland. Morphometry, immunohistology, and correlation to diseases.

The prevalence and immunoreactivity of interstitial amyloid deposits of the pituitary glands of 109 consecutive autopsies of individuals over 84 years of age were studied using Congo red staining and antibodies directed against the major amyloid fibril proteins and pituitary hormones. In addition, the amount of interstitial amyloid formation was evaluated quantitatively and compared with all autopsy-related and clinical diagnoses available. Eighty-seven (80%) of the 109 cases exhibited interstitial amyloid deposits in the anterior lobe. All reacted immunohistochemically with antiamyloid lambda light chain and antiamyloid P-component. Quantitative analysis in 62 cases revealed a mean volume percentage of interstitial amyloid in the anterior lobe of 0.56%. In statistical analysis, only two of the 25 diseases recorded were associated with interstitial amyloid: chronic obstructive pulmonary disease and non-insulin-dependent diabetes mellitus. The prevalence of chronic obstructive pulmonary disease correlated positively with the occurrence (chi 2; P < .02) as well as with the amount of amyloid (Wilcoxon; P < .04) in the pituitary. In addition, non-insulin-dependent diabetes mellitus was accompanied with higher amounts of interstitial amyloid than with all other disorders (Wilcoxon; P < .03). Until now, a correlation was proposed only between non-insulin-dependent diabetes mellitus and islet amyloidosis of the pancreas.

Aged↗

PubMed1986

Location of peptic ulcers in relation to antral and fundal gastritis by chromoendoscopic follow-up examinations.

The extent of fundal gastritis and the severity of antral gastritis in patients with duodenal ulcer and coexisting gastroduodenal ulcers were investigated using the endoscopic Congo red test. Forty-two patients with duodenal ulcer were followed-up by chromoendoscopy to investigate the location of gastric ulcers developed during the average observation period of 3.6 years in relation to the changes of fundal and antral gastritis. Duodenal ulcers were usually associated with extensive acid-secreting areas and moderate antral gastritis. In coexisting duodenal and antral ulcers, antral gastritis was usually severe, although fundal gastritis was of the same intensity as that seen with duodenal ulcers. In coexisting duodenal and high-lying ulcers, fundal gastritis was extensive and antral gastritis was severe. Follow-up studies showed that there was a significant relationship between the development of gastric ulcer and the changes of antral and fundal gastritis. Gastric ulcers developed in the antrum or the angulus in patients with duodenal ulcer when antral gastritis became worse, but no fundal gastritis spread. When fundal gastritis spread, ulcers developed in the gastric body. These findings suggested that development of increasing gastritis predicted the development of gastric ulceration and that the locations of gastric ulcer and duodenal ulcer were determined by the extent of fundal gastritis and the severity of antral gastritis.

Adult↗

PubMed2001

Self-assembly and gelation of oxidized glutathione in organic solvents.

The oxidized disulfide form of the ubiquitous tripeptide glutathione (gamma-glu-cys-gly) (GSSG) is shown to produce transparent, thermoreversible gels in aqueous solutions of dimethyl sulfoxide, dimethylformamide, and methanol, at GSSG concentrations as low as 1.5 mM. The gels bind Congo Red and exhibit dramatic green birefringence when observed between crossed polarizers, characteristic of amyloid structures. By transmission electron microscopy, the gels appear to consist of a network of fibrous structures about 75 nm in diameter. Several structurally related peptides, including the glutathione isomer glu-cys-gly and the aspartyl analogue of glutathione (beta-asp-cys-gly), failed to produce gels under similar conditions. These results suggest that the interactions which produce gelation are highly specific and that the unusual peptide geometry introduced by gamma-glu-cys linkage is critical to the gelation behavior. (1)H NMR indicates solvent-dependent perturbation of the gamma-glutamyl alpha- and beta-protons and circular dichroism reveals a shift in the geometry of the disulfide bond under conditions producing gelation. We propose that in appropriate organic solvents, GSSG self-assembles into an extended network of beta-sheetlike structures capable of immobilizing bulk solvent. While obviously speculative, it is interesting to consider possible physiological consequences of glutathione self-recognition in such processes as abnormal protein aggregation and the thiol-disulfide exchange which is believed to participate in protein folding.

Circular Dichroism↗

PubMed2005

Oxidation of low-density lipoproteins induces amyloid-like structures that are recognized by macrophages.

The macrophage scavenger receptor CD36 plays a key role in the initiation of atherosclerosis through its ability to bind to and internalize oxidized low-density lipoproteins (oxLDL). Prompted by recent findings that the CD36 receptor also recognizes amyloid fibrils formed by beta-amyloid and apolipoprotein C-II, we investigated whether the oxidation of low-density lipoproteins (LDL) generates characteristic amyloid-like structures and whether these structures serve as CD36 ligands. Our studies demonstrate that LDL oxidized by copper ions, 2,2-azobis(2-amidinopropane) dihydrochloride (AAPH), or ozone react with the diagnostic amyloid dyes thioflavin T and Congo Red and bind to serum amyloid P component (SAP), a universal constituent of physiological amyloid deposits. X-ray powder diffraction patterns for native LDL show a diffuse powder diffraction ring with maximum intensity corresponding to an atomic spacing of approximately 4.7 A, consistent with the spacing between beta-strands in a beta-sheet. Ozone treatment of LDL generates an additional diffuse powder diffraction ring with maximum intensity indicating a spacing of approximately 9.8 A. This distance is consistent with the presence of cross-beta-structure, a defining characteristic of amyloid. Evidence that these cross-beta-amyloid structures in oxLDL are recognized by macrophages is provided by the observation that SAP strongly inhibits the association and internalization of (125)I-labeled copper-oxidized LDL by peritoneal macrophages. The ability of SAP to bind to amyloid-like structures in oxLDL and prevent lipid uptake by macrophages highlights the potential importance of these structures and suggests an important preventative role for SAP in foam cell formation and early-stage atherosclerosis.

Amyloid↗

PubMed2006

Intermediate amyloid oligomers of lysozyme: Is their cytotoxicity a particular case or general rule for amyloid?

In the current study we investigated the molecular mechanisms of cytotoxicity of amyloid oligomers of horse milk lysozyme. We have shown that lysozyme forms soluble amyloid oligomers and protofibrils during incubation at pH 2.0 and 4.5 and 57 degrees C. These structures bind the amyloid-specific dyes thioflavin T and Congo Red, and their morphology and size were analyzed by atomic force microscopy. Monomeric lysozyme and its fibrils did not affect the viability of three cell types used in our experiments including primary murine neurons and fibroblasts, as well as neuroblastoma cell line IMR-32. However, soluble amyloid oligomers of lysozyme caused death of all these cell types, as estimated by flow-cytometry counting dead cells stained with ethidium bromide. The primary cell cultures appeared to be more sensitive to amyloid than neuroblastoma cell line IMR-32. Amyloid cytotoxicity depends on the size of oligomeric particles: samples containing 20-mers formed at pH 4.5 were more toxic than tetramers and octamers present in the solution at pH 2.0. Soluble amyloid oligomers can self-assemble into doughnut-like structures; however, no correlation was observed between the amount of the doughnut-like structures in the sample and its cytotoxicity. The fact that the intermediate oligomers of such an abundant protein as lysozyme display cytotoxicity confirms a hypothesis that cytotoxicity is a common feature of protein amyloid. Inhibition of intermediate oligomer formation is crucial in preventing amyloid pathogeneses.

Amyloid↗

PubMed2006

Prediction of nucleating sequences from amyloidogenic propensities of tau-related peptides.

Physical properties, including amyloid morphology, FTIR and CD spectra, enhancement of Congo red absorbance, polymerization rate, critical monomer concentration, free energy of stabilization, hydrophobicity, and the partition coefficient between soluble and amyloid states, were measured for the tau-related peptide Ac-VQIVYK amide (AcPHF6) and its single site mutants Ac-VQIVXK amide (X not equal Cys). Transmission electron microscopy showed that 15 out of the 19 peptides formed amyloid in buffer, with morphologies ranging from straight and twisted filaments to sheets and rolled sheets. Using principal component analysis (PCA), measured properties were treated in a comprehensive manner, and scores along the most significant principal components were used to define individual amino acid amyloidogenic propensities. Quantitative structure-activity modeling (QSAM) showed that residues with greater size and hydrophobicity made the largest contributions to the propensity of peptides to form amyloid. Using individual amino acid propensities, sequences within tau with high amyloid-forming potential were estimated and found to include 226VAVVR230 in the proline-rich region, 275VQIINK280 (PHF6) and 306VQIVYK311 (PHF6) within the microtubule binding region, and 392IVYK395 in the C-tail region of the protein. The results suggest that regions outside the microtubule-binding region may play important roles in tau aggregation kinetics or paired helical filament structure.

Amino Acid Substitution↗

PubMed2006

Molecular typing and virulence markers of Yersinia enterocolitica strains from human, animal and food origins isolated between 1968 and 2000 in Brazil.

Molecular typing and virulence markers were used to evaluate the genetic profiles and virulence potential of 106 Yersinia enterocolitica strains. Of these strains, 71 were bio-serotype 4/O : 3, isolated from human and animal clinical material, and 35 were of biotype 1A or 2 and of diverse serotypes, isolated from food in Brazil between 1968 and 2000. Drug resistance was also investigated. All the strains were resistant to three or more drugs. The isolates showed a virulence-related phenotype in the aesculin, pyrazinamidase and salicin tests, except for the food isolates, only two of which were positive for these tests. For the other phenotypic virulence determinants (autoagglutination, Ca(++) dependence and Congo red absorption), the strains showed a diverse behaviour. The inv, ail and ystA genes were detected in all human and animal strains, while all the food isolates were positive for inv, and 3 % of them positive for ail and ystA. The presence of virF was variable in the three groups of strains. The strains were better discriminated by PFGE than by enterobacterial repetitive intergenic consensus PCR (ERIC-PCR). A higher genomic similarity was observed among the 4/O : 3 strains, isolated from human and animal isolates, than among the food strains, with the exception of two food strains possessing the virulence genes and grouped close to the 4/O : 3 strains by ERIC-PCR. Unusually, the results revealed the virulence potential of a bio-serotype 1A/O : 10 strain, suggesting that food contaminated with Y. enterocolitica biotype 1A may cause infection. This also suggests that ERIC-PCR may be used as a tool to reveal clues about the virulence potential of Y. enterocolitica strains. Furthermore, the results also support the hypothesis that animals may act as reservoirs of Y. enterocolitica for human infections in Brazil, an epidemiological aspect that has not been investigated in this country, confirming data from other parts of the world.

Agglutination Tests↗

PubMed2002

Clinical, histopathologic, and ultrastructural characteristics of BIGH3(TGFBI) amyloid corneal dystrophies are supportive of the existence of a new type of LCD: the LCDi.

PURPOSE: To assess the morphologic differences of three types of lattice corneal dystrophies (LCDs) from histologic, immunohistochemical, and ultrastructural studies. METHODS: Corneas from three patients, one LCD1, one His626Arg-LCD, and one LCD3A were processed for Congo red, betaig-h3(541-564) antibodies immunostaining, and electron transmission microscopy studies. Control tissues were submitted to identical analyses and consisted of one cornea from a patient not having LCD and one skin biopsy from the patient suffering from LCD1. RESULTS: The three corneas displayed birefringent congophilic deposits under polarized light, confirming their amyloid nature. The deposits differed regarding their shape and location in each of the corneas. A strong immunoreactivity for betaig-h3 was shown in the LCD1 and His626Arg-LCD deposits, which was faint for the LCD3A deposits. Ultrastructural analysis confirmed the dissimilarity of the deposits among the different types of LCD. No amyloid deposits were observed in the skin from the LCD1 patient, whereas immunostaining showed the presence of high amounts of betaig-h3. CONCLUSION: Our results show that betaig-h3 is involved in amyloid deposition in all the LCDs included in the study (LCD1, His626Arg-LCD, and LCD3A). These three forms of LCD, clinically different, were also distinguishable histologically, confirming that they belong to distinctive groups of LCDs. The absence of amyloid deposition in skin from the LCD1 patient supports cornea-specific amyloid formation. In light of the present clinical, histologic, and ultrastructural data, His626Arg and related LCDs constitute a separate group of LCD that could be considered as of intermediate type on clinical grounds.

Aged↗

PubMed2000

Increased serum amyloid a levels reflect colitis severity and precede amyloid formation in IL-2 knockout mice.

The lack of sensitive and relatively non-invasive measures has hampered monitoring the clinical course of spontaneously developing colitis in IL-2-deficient (-/-) mice. We selected (i) to study the correlation of the acute phase plasma proteins serum amyloid A (SAA) and serum amyloid P component (SAP) levels with colonic disease and (ii) to characterize the amyloidosis in the IL-2(-/-)animals. IL-2(-/-)mice exhibited increasing severity of gross intestinal inflammation with age, confined to the distal colon. Histologically, the colonic disease score increased serially in IL-2(-/-)animals. Wild-type mice showed no activity, while 16-week-old IL-2(+/-)animals had minimal colitis with small ulcers and lamina propria inflammatory infiltrate. Periportal hepatitis was present and positive Congo red staining indicated amyloidosis of the liver and spleen in 16 week IL-2(-/-)mice. SAA immunostaining in the liver and spleen was increased in the 8 week and 16 week IL-2(-/-)and 16 week IL-2(+/-)animals indicating AA amyloid deposits. Plasma SAA and SAP levels were markedly elevated, and generally preceded the onset of colitis and reflected its severity. Northern analysis showed markedly increased SAA expression in the liver and intestine of IL-2(-/-)and intestine of IL-2(+/-)16-week-old animals. Increased intestinal expression of SAA3 (lamina propria macrophages) indicates local inflammation in IL-2(+/-)animals at 16 weeks. Treatment of 3-week-old animals with systemic IL-2 or IL-1 receptor antagonist (IL-1ra) delayed inflammation, postponed the increase in SAA levels and minimized disease onset. These results further demonstrate that IL-2 plays a significant role in normal immune responses in the body and that plasma SAA levels both reflect colonic disease severity and may indicate subclinical disease in both IL-2(-/-)and IL-2(+/-)mice. Furthermore. The mechanism of IL-2-deficient induced colitis appears to be mediated in part through the increase in IL-1. In addition, the IL-2(-/-)mouse of spontaneous enterocolitis may provide a unique system for studying spontaneously developing AA amyloidosis.

Amyloidosis↗

PubMed2003

Amyloid-like fibril formation in an all beta-barrel protein. Partially structured intermediate state(s) is a precursor for fibril formation.

Acidic fibroblast growth factor from newt (Notopthalmus viridescens) is a approximately 15-kDa, all beta-sheet protein devoid of disulfide bonds. In the present study, we investigate the effects of 2,2,2-trifluoroethanol (TFE) on the structure of newt acidic fibroblast growth factor (nFGF-1). The protein aggregates maximally in 10% (v/v) TFE. Congo red and thioflavin T binding experiments suggest that the aggregates induced by TFE have properties resembling the amyloid fibrils. Transmission electron microscopy and x-ray fiber diffraction data show that the fibrils (induced by TFE) are straight, unbranched, and have a cross-beta structure with an average diameter of 10-15 A. Preformed fibrils (induced by TFE) of nFGF-1 are observed to seed amyloid-like fibril formation in solutions containing the protein (nFGF-1) in the native beta-barrel conformation. Fluorescence, far-UV CD, anilino-8-napthalene sulfonate binding, multidimensional NMR, and Fourier transformed infrared spectroscopy data reveal that formation of a partially structured intermediate state(s) precedes the onset of the fibrillation process. The native beta-barrel structure of nFGF-1 appears to be disrupted in the partially structured intermediate state(s). The protein in the partially structured intermediate state(s) is found to be "sticky" with a solvent-exposed non-polar surface(s). Amyloid fibril formation appears to occur due to coalescence of the protein in the partially structured intermediate state(s) through solvent-exposed non-polar surfaces and intermolecular beta-sheet formation among the extended, linear beta-strands in the protein.

Amyloid beta-Peptides↗

PubMed1989

Correlation of sperm and endocrine measures with reproductive success in rodents.

This paper compares the statistical precision and biological sensitivity of multiple indices of reproductive function to infertility in the male rodent. The studies discussed include those that examined reproductive function in the male following perinatal exposure to reproductive toxicants and others in which the compounds were administered to young-adult males, often with very diverse results. For example, some chemicals that alter sex differentiation reduce fertility by affecting breeding performance alone (polychlorinated biphenyls (PCBs), fenarimol, or losulazine), without altering sperm and testicular measures. Others also markedly alter sex differentiation of the genitalia, the accessory glands and the testis in addition to their effects on central nervous system (CNS) sex differentiation and mating behavior (testosterone, flutamide, cyproterone acetate, tamoxifen, estradiol and diethylstilbestrol (DES)). In contrast, prenatal exposure to compounds that alter primary germ cell survival (busulphan, congo red) induce partial gonadal/germ cell agenesis without altering sex differentiation. These chemicals dramatically reduce testicular sperm production in the male offspring, and the most severely affected males are infertile. In a series of studies conducted in our laboratory, young male rats were exposed to known reproductive toxicants in a dose related manner from puberty, through young adulthood and breeding. We have found that the profile of effects varies considerably depending upon the chemical's mechanism of toxicity. When a compound produced infertility through direct effects of testicular function (Carbendazim (MBC) and dibutyl phthalate (DBP)), then testis weight, testicular histology, and testicular sperm head counts provided sensitive indicators of toxicity. In general, dramatic reductions in sperm production are required to induce infertility and these changes were accompanied by elevated serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and changes in human chorionic gonadotropin (hCG)-stimulated testosterone synthesis. Chemicals that have hormonal activity, alter the internal endocrine environment, or directly effect CNS function induce a completely different profile of effects. For example, estrogen administration alters the function of the seminal vesicle and the endocrine system, and reduces epididymal sperm reserves; while testicular measures are relatively unaffected. Since very different spectrums of effects are produced by different compounds, no single endpoint will consistently be the most sensitive indicator of reproductive toxicity.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed1996

Proximal gastric vagotomy. Comparison between open and laparoscopic methods in the canine model.

OBJECTIVE: The authors compared open and laparoscopic proximal gastric vagotomies for efficacy of acid reduction and preservation of gastric emptying. SUMMARY BACKGROUND DATA: Laparoscopic methods have been used to perform vagotomy in patients with duodenal ulcer; however, no direct comparisons are available of laparoscopic and open surgical procedures regarding acid reduction and gastric emptying. METHODS: Thirty-one consecutive dogs were randomized to open proximal gastric vagotomy (OPGV; n = 11), laparoscopic anterior seromyotomy and posterior truncal vagotomy (ASPTV; n = 10), or laparoscopic proximal gastric vagotomy (LPGV; n = 10). Intraoperative endoscopic Congo red testing assured complete vagotomy. Basal acid output (BAO) and maximal acid output (MAO) during pentagastrin and insulin-induced hypoglycemia were measured with marker dilution techniques, and gastric emptying was assessed with radionuclide-labelled solid and liquid markers before and 5 weeks after operation. RESULTS: Operative time (mean +/- standard error of the mean) for OPGV was shorter compared with ASPTV and LPGV (86 +/- 7 minutes vs. 124 +/- 7 minutes and 115 +/- 7 minutes; p < 0.002). Postoperative BAO did not decrease in any group. Open proximal gastric vagotomy and LPGV, but not ASPTV, decreased MAO (p < 0.05); (after pentagastrin, OPGV from 26.4 +/- 1.7 mEq/hour to 11.3 +/- 0.1 mEq/hour, LPGV from 21.4 +/- 1.0 mEq/hour to 6.4 +/- 0.5 mEq/hour; after insulin-induced hypoglycemia, OPGV from 9.9 +/- 0.5 mEq/hour to 2.2 +/- 0.3 mEq/hour, LPGV from 7.9 +/- 0.5 mEq/hour to 1.9 +/- 0.4 mEq/hour). Gastric emptying of liquids and solids, as quantitated by the time for one half of the marker to empty (T 1/2) and the shape of the emptying curve, were similar before and after all three surgical procedures. CONCLUSIONS: Laparoscopic proximal gastric vagotomy was comparable to OPGV in decreasing stimulated gastric acid production without significantly altering gastric emptying. Anterior seromyotomy and posterior truncal vagotomy was less effective in decreasing MAO and required more operative time. Laparoscopic proximal gastric vagotomy has the potential to become accepted therapy for patients with duodenal ulcer managed presently with OPGV.

Animals↗

PubMed2006

Oleic acid inhibits amyloid formation of the intermediate of alpha-lactalbumin at moderately acidic pH.

The effects of oleic acid on amyloid formation of Ca2+-depleted bovine alpha-lactalbumin (apo-BLA) at low pH and the biological impact of the effects were investigated by using thioflavin T, Congo red, far-UV circular dichroism, atomic force microscopy, transmission electron microscopy, and other biophysical methods. The results from the phase diagram method of fluorescence show that two intermediates exist in the conformational transition of apo-BLA induced by low pH. One intermediate populated at pH 3.0 is characterized as a molten globule state and the other accumulates with stable secondary structure and exposed hydrophobic surface at pH 4.0-4.5. Amyloid formation of apo-BLA takes place upon decreasing the pH to 4.5 and is accelerated remarkably as the pH is decreased further. However, amyloid fibrils of apo-BLA are not observed in the pH range of 5.0-7.0 on a time-scale of 30 days. The lag time of fibrillation at pH 4.0 is greatly elongated by the presence of oleic acid, accompanied by a remarkable decline of the maximum thioflavin T intensity. Furthermore, amyloid formation of apo-BLA at pH 4.5 is inhibited completely by oleic acid, and insoluble aggregates are observed. In contrast, the effects of oleic acid on amyloid formation are not remarkable at pH 3.0 or at pH 2.0. Our data demonstrate that oleic acid specifically induces the intermediate of apo-BLA at pH 4.0-4.5 to form insoluble amorphous aggregates, which is responsible for the inhibition of amyloid formation of the protein by oleic acid in this range of pH values.

Amyloid↗

PubMed2000

Histochemical and immunohistochemical differential diagnosis of amyloidosis--a brief illustrated essay and personal experience with Romhányi's method.

The histochemical and immunohistochemical differential diagnosis of amyloidosis in surgical pathology in a referral center is presented. Different forms of amyloidosis are considered e.g. systemic generalized amyloidosis: secondary (AA), primary (AL), senile, hemodialysis-associated, hereditary and organ (tissue)-limited (localized) amyloidosis: cerebral, dystrophic (age-related, so-called "senile"), endocrine-related, localized to tumours, focal (concentrated secretion), and isolated plasma cell (solitary plasmacytoma, B-cell) dyscrasia related amyloidosis. The amyloid deposits were identified and characterized histochemically by Congo red staining after performate pre-treatment at 20 degrees C for 1, 3, 5, 10, 15, 20 or 25 sec, and with oxidation induced proteolysis by trypsin digestion at 20 degrees C for 5, 10, or 30 sec, 1, 2, 3, 4, 5, 6 or 10 min and covered with gum-arabic according to Romhányi, and confirmed by streptavidin-biotin-complex/horseradish peroxidase immunohistochemical reactions. The "sensitivity" or "resistance" to pre-treatment of amyloid deposits depends on the type of amyloid, and the length of pre-treatment. Secondary (AA) amyloid is sensitive to KMnO4 oxidation, followed by trypsin digestion (for 1 min), and its green birefringence under polarized light disappears, while primary (AL) (for 1-5 min), senile (for 1-10 min), and most forms of organ (tissue)-limited (localized) amyloid (for 1-10 min) are resistant. Performate pre-treatment is followed by pronounced congophilia. Secondary (AA) is sensitive to performate pre-treatment (for 1 sec), while primary (AL) amyloid (for 1-20 sec), senile (for 1-25 sec), and most forms of organ (tissue)-limited (localized, isolated) amyloid deposits (for 1-25 sec) are resistant, and are constantly positively birefringent. Early identification and differentiation of amyloid deposits is important for the prognosis and for the choice of therapy. The authors conclude that the presented classical histochemical methods are useful as first line screens for the histological identification of amyloidosis.

Amyloid↗

PubMed2006

The CRH family coding for cell wall glycosylphosphatidylinositol proteins with a predicted transglycosidase domain affects cell wall organization and virulence of Candida albicans.

In Candida albicans UTR2 (CSF4), CRH11, and CRH12 are members of a gene family (the CRH family) that encode glycosylphosphatidylinositol-dependent cell wall proteins with putative transglycosidase activity. Deletion of genes of this family resulted in additive sensitivity to compounds interfering with normal cell wall formation (Congo red, calcofluor white, SDS, and high Ca(2+) concentrations), suggesting that these genes contribute to cell wall organization. A triple mutant lacking UTR2, CRH11, and CRH12 produced a defective cell wall, as inferred from increased sensitivity to cell wall-degrading enzymes, decreased ability of protoplasts to regenerate a new wall, constitutive activation of Mkc1p, the mitogen-activated protein kinase of the cell wall integrity pathway, and an increased chitin content of the cell wall. Importantly, this was accompanied by a decrease in alkali-insoluble 1,3-beta-glucan but not total glucan content, suggesting that formation of the linkage between 1,3-beta-glucan and chitin might be affected. In support of this idea, localization of a Utr2p-GFP fusion protein largely coincided with areas of chitin incorporation in C. albicans. As UTR2 and CRH11 expression is regulated by calcineurin, a serine/threonine protein phosphatase involved in tolerance to antifungal drugs, cell wall morphogenesis, and virulence, this points to a possible relationship between calcineurin and the CRH family. Deletion of UTR2, CRH11, and CRH12 resulted in only a partial overlap with calcineurin-dependent phenotypes, suggesting that calcineurin has additional targets. Interestingly, cells deleted for UTR2, CRH11, and CRH12 were, like a calcineurin mutant, avirulent in a mouse model of systemic infection but retained the capacity to colonize target organs (kidneys) as the wild type. In conclusion, this work establishes the role of UTR2, CRH11, and CRH12 in cell wall organization and integrity.

Animals↗

PubMed1999

Supramolecularity creates nonstandard protein ligands.

Congo red and a group of structurally related dyes long used to stain amyloid proteins are known to associate in water solutions. The self-association of some dyes belonging to this group appears particularly strong. In water solutions their molecules are arranged in ribbon-like micellar forms with liquid crystalline properties. These compounds have recently been found to form complexes with some native proteins in a non-standard way. Gaps formed by the local distribution of beta-sheets in proteins probably represent the receptor sites for these dye ligands. They may result from higher structural instability in unfolding conditions, but also may appear as long range cooperative fluctuations generated by ligand binding. Immunoglobulins G were chosen as model binding proteins to check the mechanism of binding of these dyes. The sites of structural changes generated by antigen binding in antibodies, believed to act as a signal propagated to distant parts of the molecule, were assumed to be suitable sites for the complexation of liquid-crystalline dyes. This assumption was confirmed by proving that antibodies engaged in immune complexation really do bind these dyes; as expected, this binding affects their function by significantly enhancing antigen binding and simultaneously inhibiting C1q attachment. Binding of these supramolecular dyes by some other native proteins including serpins and their natural complexes was also shown. The strict dependence of the ligation properties on strong self-assembling and the particular arrangement of dye molecules indicate that supramolecularity is the feature that creates non-standard protein ligands, with potential uses in medicine and experimental science.

Animals↗

PubMed1988

Negative correlations between parenchymal amyloid and vascular amyloid in hippocampus.

Congo red was used to stain amyloid in 29 blocks of hippocampus from 17 unselected cases of Alzheimer's disease. Green birefringence under polarized light was used for evaluation of the average number of senile plaques and cross-sectional vessel profiles containing amyloid in five fields per slide, at a magnification of X100. Fields were selected that had large numbers of neurofibrillary tangles, also counted on the basis of green birefringence. The vascular involvement by amyloid was expressed as the ratio of amyloid positive to amyloid negative profiles. A negative correlation was found between Congophilic plaques or tangles on the one hand and vascular amyloid content on the other. In other words, cases with large numbers of Congophilic plaques had fewer Congophilic vessels, and vice versa: congophilic plaques = -3 (vessel amyloid) + 2.2, Spearman correlation coefficient, -0.61, P less than 0.01; tangles = -3.7 (vessel amyloid) + 15.6, Spearman correlation coefficient, -0.05, P greater than 0.05. When the slides were reexamined, using only fields with at least one Congophilic vessel, the negative correlation for plaque versus vessel amyloid remained highly significant, whereas that for tangles versus vessel amyloid became highly significant: Congophilic plaques = -1.2 (vessel amyloid) + 2.3, Spearman correlation coefficient, -0.48, P less than 0.01; tangles = -5 (vessel amyloid) + 19, Spearman correlation coefficient, -0.48, P less than 0.01. These data are most compatible with the hypothesis that amyloid is first produced in the parenchyma and is somehow cleared by the vessels. It is least compatible with the hypothesis that the amyloid precursor protein first enters the vessel wall to produce amyloid there, and then moves into the brain to produce amyloid in parenchymal sites.

Aged↗