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At least 829 records · Page 46Linked to original sources
PubMed2004

The HPV16 E7 viral oncoprotein self-assembles into defined spherical oligomers.

Despite the fact that E7 is a major transforming oncoprotein in papillomavirus, its structure and precise molecular mechanism of action remain puzzling to date. E7 proteins share sequence homology and proteasome targeting properties of tumor suppressors with adenovirus E1A and SV40 T antigen, two other paradigmatic oncoproteins from DNA tumor viruses. High-risk HPV16 E7, a nonglobular dimer with some properties of intrinsically disordered proteins, is capable of undergoing pH-dependent conformational transitions that expose hydrophobic surfaces to the solvent. We found that treatment with a chelating agent produced a protein that can readily assemble into homogeneous spherical particles with an average molecular mass of 790 kDa and a diameter of 50 nm, as determined from dynamic light scattering and electron microscopy. The protein undergoes a substantial conformational transition from coil to beta-sheet structure, with concomitant consolidation of tertiary structure as judged by circular dichroism and fluorescence. The assembly process is very slow, in agreement with a substantial energy barrier caused by structural rearrangements. The resulting particles are highly stable, cooperatively folded, and capable of binding both Congo Red and thioflavin T, reporters of repetitive beta-sheet structures similar to those found in amyloids, although no fibrillar or insoluble material was observed under our experimental conditions.

Benzothiazoles↗
PubMedDate not supplied

Proximal gastric vagotomy by minimally invasive methods in an acute rat model.

In this prospective study, minimally invasive methods of proximal gastric vagotomy (PGV) were investigated in male Sprague-Dawley rats. Completeness of vagotomy by traditional operative therapy, by laser denervation of the gastric serosa, and by subserosal or transmucosal injections of chemoneurolytic agents was evaluated with postoperative Congo red testing, ulcerogenic stimulation of the gastric mucosa, and histochemical labeling of whatever vagal fibers remained in the gastric wall. Short-term results demonstrate that successful PGV can be performed with minimally invasive methods.

Animals↗
PubMed2002

Dye biosorption sites in Aspergillus niger.

Aspergillus niger is capable of removing dyes from an aqueous solution. In the study, the roles played by three major functional groups: carboxyl, amino and phosphate, and the lipid fraction in the biomass of A. niger in biosorption of four dyes, Basic Blue 9, Acid Blue 29, Congo Red and Disperse Red 1, were investigated. These functional groups in A. niger were chemically modified individually to determine their contribution to the biosorption of dyes. It was found that biosorption of dyes was influenced by the functional groups in the fungal biomass and the chemical structure of the dyes.

Absorption↗
PubMed1993

Posterior truncal vagotomy and stapling of the anterior stomach wall in 30 patients with duodenal ulcer: acid inhibition, gastric emptying, and endoscopic dye spraying. Prospects for endoscopic vagotomy.

The use of a stapling instrument (TA90) to effect a transection of the anterior gastric wall with posterior truncal vagotomy but preserving innervation to the anterior wall of the antrum for duodenal ulcer is described. The operation resulted in the endoscopic healing of all the ulcers; however, recurrent ulceration was seen in 3 of 25 patients. Basal acid output was reduced from 7.84 (SEM 1.73) to 3.49 (SEM 1.15) mmol/h (t = 2.09, df = 15.7, p = 0.05), while peak acid output was reduced from 38.67 (SEM 3.11) to 19.26 (SEM 2.3) mmol/h (t = 5.01, df = 23.9, p = 0.0000). Solid and liquid gastric emptying studies were performed, and while some delay in solid emptying was seen, only one patient complained of transient gastric stasis. Endoscopic Congo red staining was performed postoperatively and a tongue of innervated mucosa along the lesser curve was seen in each case. The procedure was easily and rapidly performed, and early clinical results are good, with 25 of 30 patients having a good (Visick I) result.

Adult↗
PubMed1985

A rapid spectrophotometric method for assessing macrophage phagocytic activity.

The method described provides a rapid and inexpensive in vitro assay of phagocytosis by mononuclear phagocytes. This assay utilizes yeast cells, stained with congo red, as the target particle and quantitation is performed spectrophotometrically. An attractive feature of this assay is that phagocytic activity is assessed using large sample sizes, in this case approximately 1 X 10(6) macrophages per sample, resulting in a more accurate evaluation of phagocytosis than assays dependent on microscopic quantitation.

Animals↗
PubMed1996

Beta-amyloid induces apoptosis in human-derived neurotypic SH-SY5Y cells.

Alzheimer's disease is primarily characterized by neurofibrillary tangles, senile plaques, and neurodegeneration. The major component of senile plaques is the beta-amyloid peptide (beta A4), which has been shown to be toxic to neurons in vitro. To date, the mechanism of beta A4-induced neurotoxicity has not been determined in human-derived neurons. In this report, we present evidence that programmed cell death, or apoptosis, is involved in the neurotoxic activity of beta A41-40 and beta A425-35 in the human-derived neurotypic cell line SH-SY5Y cells. The evidence for beta A4-induced apoptosis includes: (1) labeling of cell nuclei for DNA nicked ends; (2) morphological changes in ultrastructure that are consistent with apoptosis (shrunken cells with pyknotic nuclei); (3) DNA laddering which can be blocked by aurintricarboxylic acid (ATA), an inhibitor of apoptosis; and (4) marginal release of intracellular lactate dehydrogenase (LDH), an indicator of necrosis. These results suggest that apoptosis is the major event involved in beta A4-induced cytotoxicity in SH-SY5Y cells. A variety of reagents were tested to determine their activities against beta A4-induced DNA laddering. Nerve growth factor and free radical scavengers were inactive in this system. While ATA blocked DNA laddering resulting from either beta A4 or okadaic acid treatment, Congo red specifically attenuated only beta A4-induced DNA fragmentation. These results suggest that compounds which bind fibrillar beta-peptides can protect this human neurotypic cell line against apoptosis induced by beta A4.

Amyloid beta-Protein Precursor↗
PubMed2000

Acid transport through channels in the mucous layer of rat stomach.

BACKGROUND & AIMS: We have reported previously that secreted acid moves through the mucous layer in restricted areas above the gastric crypts. The aim of this study was to visualize and study the dynamics of this event. METHODS: Anesthetized rats prepared for intravital microscopy of the gastric mucosa were divided in the following groups with respect to acid secretion: spontaneous; stimulated (pentagastrin, 40 microg. kg(-1). h(-1)); transiently inhibited (omeprazole, 400 micromol. kg(-1) for 7 days); and totally inhibited (omeprazole, 3 x 200 micromol. kg(-1) for 7 days). The mucus was stained with Congo red (blue, pH < 3; red, pH > 5.2), and photographs were taken through a stereomicroscope. RESULTS: During acid secretion, blue-colored crypt openings with attached thread-like (5-7 microm wide) structures (designated channels) were seen passing from the crypt openings through the mucus to the lumen. Red-colored channels and crypt openings were observed when acid secretion was transiently inhibited. Red-colored crypt openings but no channels were found after total inhibition of acid secretion for a week. CONCLUSIONS: The results suggest that secreted acid is transported through channels within the mucus. These channels are probably created by the high intraglandular pressure pushing acid and glandular mucus into the gel.

Animals↗
PubMed1980

Demonstration of amyloid in murine and human secondary amyloidosis by the immunoperoxidase technique.

A specific rabbit anti-murine amyloid A protein (anti-AA) has been used in the immunoperoxidase (IP) technique for the detection of amyloid in formalin-fixed, paraffin-embedded, tissue obtained from amyloidotic mice and a post-mortem kidney specimen from a patient with amyloidosis secondary to osteomyelitis. Amyloidosis was induced in five out of 20 white mice by weekly intraperitoneal injections of complete Freund's adjuvant. Amyloid deposits were clearly demonstrated both by the Congo Red and by the IP techniques. The antibody against murine AA was found to be cross-reactive with human AA. These preliminary results suggest that the IP technique with the use of specific antibodies against the different amyloid proteins might be extremely useful for the histological dianosis and classification of amyloidosis.

Amyloid↗
PubMed1988

An analysis of developmental timing in Blastocladiella emersonii sporulation.

We propose a model of time regulation for the expression of the Blastocladiella emersonii sporulation phenotypes based on new methods (Soll, 1986) which analyse the effect of temperature on the rate limiting processes, i.e., "timers" of certain events during development. By using reciprocal shift experiments (transferring sporulating cells from 22 to 27 degrees C and vice versa) we characterized the timers of the phenotypes: septate zoosporangium, papillate zoosporangium, cleavage zoosporangium, and empty zoosporangium, considering the number of the components, sensitivity, duration, and the mutual dependency of each limiting factor. The timers for the first three phenotypes started at zero time of sporulation induction and acted in parallel. The fourth phenotype, empty zoosporangium, has a timer which appears to act sequentially to that of the papillate zoosporangium. We also studied the effects of polyoxin D, calcofluor white, and congo red on sporulation. The first drug prevents the appearance of the septate zoosporangium and the other two prevent the expression of the papillate zoosporangium. In spite of the morphological blockage, the zoosporogenesis proceeds, resulting in the formation of normal zoospores. These results are interpreted as additional evidence for the parallel model of control proposed here.

Benzenesulfonates↗
PubMed2004

Techniques to study amyloid fibril formation in vitro.

Amyloid fibrils are ordered aggregates of peptides or proteins that are fibrillar in structure and contribute to the complications of many diseases (e.g., type 2 diabetes mellitus, Alzheimer's disease, and primary systemic amyloidosis). These fibrils can also be prepared in vitro and there are three criteria that define a protein aggregate as an amyloid fibril: green birefringence upon staining with Congo Red, fibrillar morphology, and beta-sheet secondary structure. The purpose of this review is to describe the techniques used to study amyloid fibril formation in vitro, address common errors in the collection and interpretation of data, and open a discussion for a critical review of the criteria currently used to classify a protein aggregate as an amyloid fibril.

Amyloid↗
PubMed1997

Human A beta-amyloid and amyloid precursor protein accumulates in rat brain cells after cultured human leptomeningeal fibroblast implants.

Cultured human leptomeningeal fibroblasts grafted into rat frontal cortex were localized to the implant pocket and to adjacent host leptomeninges. Immunohistochemical studies using a panel of human-specific and domain-specific APP antibodies revealed that all grafted cells expressed both APP and A beta in situ. Remarkably, these antibodies also labeled rat pial and ependymal cells as well as reactive astrocytes adjacent to vessels. In addition, apical projections and cell bodies of many cortical pyramidal neurons contained human-specific APP immunoreactive material. Groups of subcortical neurons, particularly those of the amygdala, hippocampal formation and suprachiasmatic nuclei, were similarly labeled. The presence of human APP in host brains was confirmed by immunoblotting. Birefringent Congo Red staining was observed in the cortical neuropil and in leptomeningeal vessels. These data indicate that grafted leptomeningeal fibroblasts hyperexpress APP and A beta which can diffuse into parenchyma and be taken up by specific rat cells.

Amyloid beta-Peptides↗
PubMed1994

Extraction of amyloid-like fibrils from chronically inflamed periodontal tissues.

Immunohistological studies have established an association between the deposition of the amyloid P protein and disease status in chronically inflamed periodontal tissues. The aim of this study was to determine if amyloid-like fibrils could be extracted from these tissues. Biopsies were homogenised and extracted exhaustively in saline before serial extraction in distilled water. Electrophoretic analysis revealed the presence of previously undetected protein bands in the fifth water extraction. These were probed and were found to react with antisera to kappa and lambda immunoglobulin light chains but not with antisera to mu, gamma or alpha heavy chains. Electron microscopic study indicated fibrils of 9.7 nm diameter. These bound Congo Red and exhibited green birefringence under polarised light. The results supported the presence of an amyloid-like matrix composed of immunoglobulin light chains in the lesions of chronic periodontitis. This could explain the persistence of foci of degenerate plasma cells and the paucity of granulation tissue formation in the disease process.

Amyloid↗
PubMed1995

Conformational mimicry in Alzheimer's disease. Role of apolipoproteins in amyloidogenesis.

Several apolipoproteins are known to be closely associated with amyloid fibrillogenesis. Serum amyloid A, apolipoprotein (apo) AII and apo A1 are each deposited as biochemically distinct forms of amyloid. Late-onset Alzheimer's disease is linked to one isotype of apo E, apo E4. Apo E and apo E4 in particular have been shown to modulate amyloid fibril formation by amyloid-beta peptides in vitro. Furthermore, the carboxy terminus of apo E has been shown to be a constituent of plaque amyloid. We show immunohistochemically and electron microscopically the presence of apo A1 in senile plaques. The intact apo A1 can itself form amyloid-like fibrils in vitro that are Congo Red positive. We propose that some proteins when misfolded can propagate this misfolding to identical units, either autocatalytically or to other proteins that are induced to fold into the same abnormal conformation. This conformational mimicry may initiate and/or augment fibrillogenesis in Alzheimer's disease.

Alzheimer Disease↗
PubMedDate not supplied

Secondary amyloidosis in a corneal graft.

PURPOSE: To describe a case of secondary amyloidosis that occurred in a corneal graft. METHODS: A 30-year-old Japanese woman had opacities in the corneal graft in her right eye. Slit-lamp microscopy examination demonstrated nodular, subepithelial opacities in the graft. Results of a physical examination and her past medical history were unremarkable, except for a history of a penetrating keratoplasty for keratoconus at the age of 17. Since then, the patient had worn a hard contact lens for over 10 years. The specimen obtained by keratectomy was examined histologically. RESULTS: The histologic examination revealed hyaline, and amorphous materials stained with Congo red, which were dichroic under polarized light. Transmission electron microscopy showed the characteristic fibrillar pattern of amyloid. CONCLUSIONS: This appears to be the first reported case of secondary amyloidosis in a corneal graft. A long-standing history of hard contact lens wear may play a role in the pathogenesis of this rare condition.

Adult↗
PubMed2003

Aspiration cytology diagnosis of a primary amyloid tumor of thoracic vertebra: a case report.

Isolated primary amyloid tumor of bone is rare; however, preoperative diagnosis can be rewarding because the prognosis is excellent. There are no clinical or roentgenographic criteria that can establish this diagnosis. There are few previous reports of fine-needle aspiration (FNA) where diagnosis of amyloidoma was made retrospectively. They describe the presence of extracellular hyaline material along with plasma cells and lymphocytes. A 35-year-old female was referred to the FNA clinic with swelling in the right upper chest wall. Radiologic findings revealed a destructive lytic lesion involving the bodies of D1 and D2 vertebrae with extension into surrounding soft tissue. Repeated FNA smears were hypocellular but had abundant homogeneous flocculent material, which stained positive with Congo red. A few plasma cells and foreign-body giant cells were also seen. We conclude that preoperative FNA cytology diagnosis of amyloid tumor is possible. Hypocellular smears with flocculent material, plasma cells, and foreign-body giant cells in absence of granulation tissue should suggest the diagnosis.

Adult↗
PubMed2002

Inhibitors of fibril formation and cytotoxicity of beta-amyloid peptide composed of KLVFF recognition element and flexible hydrophilic disrupting element.

Beta-Amyloid peptide (Abeta) is the main protein components of neuritic plaques and its neurotoxicity would be exposed by formation of aggregate. The aggregation inhibitors composed of an Abeta recognition element (KLVFF) and a flexible hydrophilic disrupting element (aminoethoxy ethoxy acetate and aspartate) are designed and chemically synthesized. The inhibitory effects are examined by a pigment binding assay using Congo red or thioflavin T. The present compounds suppress the formation of aggregate, and the compound DDX3 is an especially effective inhibitor. In addition, the synthesized compounds efficiently suppress the cytotoxicity of Abeta against IMR-32 neuroblastoma cells in vitro.

Amyloid beta-Peptides↗
PubMed2000

Amyloid arthropathy revealed by RS3PE syndrome.

Amyloid arthropathy is a form of primary AL amyloidosis with a monoclonal component in the blood and/or urine, and RS3PE syndrome is acute edematous polysynovitis in subjects older than 60 years. A 74-year-old man was diagnosed with both disorders. He was admitted for benign acute polyarthritis of the hands and feet and reported carpal tunnel symptoms predominating on the right. A synovial biopsy at the right wrist disclosed deposits that stained with Congo red even after potassium permanganate treatment (positive Wright's test). Articular AL amyloidosis was diagnosed. The symptoms resolved under glucocorticoid therapy alone, casting some doubt on their relationship with the amyloidosis. Roentgenograms showed geodes, a feature not present in RS3PE. Whether RS3PE may be among the possible presentations of articular amyloidosis is discussed.

Aged↗
PubMed1980

Studies on acid protease fractions and gastric mucosal atrophy. 2. Relationship of acid proteases in gastric juice separately determined by alkali treatment and gastric mucosal atrophy.

The relationships of two acid protease groups, alkali labile pepsin (ALP) and alkali stable pepsin (ASP), and gastric mucosal atrophy, were studied. ALP and ASP were determined separately by alkali treatment. The extent of fundic gland atrophy was detected by endoscopic congo red test. The subjects of the study were 10 normal subjects and 64 patients with gastroduodenal disease. In all subjects, both ALP and ASP outputs were increased by tetragastrin administration while ASP:ALP ratio was decreased by the provocation. ALP output was reduced in parallel with the extent of fundic gland atrophy whereas ASP output was kept until the atrophy became severe.

Adult↗