Classification of Glanzmann's thrombasthenia based on the intracellular transport pathway of GPIIb-IIIa.
Explore the source record for details and available documents.
Biological Transport, Active↗
Biomedical subjects
A Kato
Publications and source records attributed to A Kato.
Single-stranded DNA of 5'-upstream region of the rolC gene interacts with nuclear proteins of carrot cell cultures.
Using the gel retardation assay, proteins of carrot cells capable of binding to a single-stranded DNA of 5'-upstream region of the rolC gene were found. From competition experiments, these DNA-protein interactions were specific to single-stranded nucleotide sequence of Ava S fragment (from -94 bp to +23 bp relative to the transcription initiation site). Methylation interference experiments showed that G residue at the position of -41 bases on the bottom strand was important for DNA-protein binding. This residue was located between CAAT box and TATAA box. Such specific interaction between single-stranded DNA and nuclear proteins may play a role in transcription by RNA polymerase II.
Base Sequence↗
Molecular weight determination and compositional analysis of dextran-protein conjugates using low-angle laser light scattering technique combined with high-performance gel chromatography.
The low-angle laser light scattering technique combined with high-performance gel chromatography was applied for characterization of the dextran-ovalbumin and dextran-lysozyme conjugates obtained from the mild heating in dry state, which is attracting interest as a way leading to stabilization of proteins and to production of proteins with excellent emulsifying or antimicrobial ability (Nakamura, S., Kato, A. and Kobayashi, K. (1991) J. Agric. Food Chem. 39, 647-650). According to the above technique, providing the information about the molecular weight distribution and the composition of the conjugates, one or two dextran molecules were found to be linked to one molecule of the proteins. In addition, each of the conjugates was shown to exist as an oligomeric assembly of which formation is promoted by an increase in the salt concentration of buffer. The observations suggest that the increase in the hydrophobicity of the protein moiety as a result of partial denaturation and the introduction of the hydrophilic dextran chain affords the conjugate an amphiphilic property.
Chromatography, Gel↗
Secretin stimulates exocytosis in isolated bile duct epithelial cells by a cyclic AMP-mediated mechanism.
Intrahepatic bile duct epithelial cells, or cholangiocytes, contribute to bile secretion in response to hormones, including secretin. However, the mechanism by which secretin stimulates ductular bile flow is unknown. Since recent data in nonhepatic epithelia have suggested a role for exocytosis in fluid secretion, we tested the hypothesis that secretin stimulates exocytosis by isolated cholangiocytes. Cholangiocytes were isolated from normal rat liver by a newly described method employing enzymatic digestion and mechanical disruption followed by immunomagnetic separation using specific monoclonal antibodies, and exocytosis was measured using a fluorescence unquenching assay employing acridine orange. Secretin caused a dose-dependent (10(-12)-10(-7) M) increase in acridine orange fluorescence by acridine orange-loaded cholangiocytes with a peak response at 10 min; the half-maximal concentration of secretin was 7 x 10(-9) M. The secretin effect was inhibited by preincubation of cholangiocytes with colchicine (30% inhibition, p less than 0.05) or trypsin (90% inhibition, p less than 0.001); no inhibition was seen with lumicolchicine and heat-inactivated trypsin. Cholecystokinin, insulin, and somatostatin had no effect on fluorescence of acridine orange-loaded cholangiocytes; secretin had no effect on fluorescence of acridine orange-loaded hepatocytes or hepatic endothelial cells. Exposure of isolated cholangiocytes to secretin at doses that stimulated exocytosis caused a dose-dependent increase in cyclic AMP levels (218% maximal increase, p less than 0.05); moreover, an analogue of cyclic AMP stimulated exocytosis by cholangiocytes. Secretin had no effect on intracellular calcium concentration using Fura-2-loaded cholangiocytes assessed by digitized video microscopy. Our results demonstrate, for the first time, that secretin stimulates exocytosis by rat cholangiocytes. The effect is cell- and hormone-specific, dependent on intact microtubules, on a protein(s) on the external surface of cholangiocytes, and on changes in cellular levels of cyclic AMP. The results are consistent with the hypothesis that secretin-induced changes in bile flow may involve an exocytic process.
Animals↗
Y-29794--a non-peptide prolyl endopeptidase inhibitor that can penetrate into the brain.
A novel non-peptide prolyl endopeptidase (PPCE) inhibitor, Y-29794, has been identified. Y-29794 selectively and competitively inhibited rat brain PPCE (Ki = 0.95 nM) in a reversible manner. Ex vivo study demonstrated that Y-29794 could penetrate into brain to exhibit dose-dependent and long-lasting inhibition. Furthermore, Y-29794 was found to potentiate the effect of TRH on the release of ACh in the rat hippocampus. These results indicate that Y-29794 is an orally active, potent and specific PPCE inhibitor and should be of value in studies on the physiological role of the enzyme in neuropeptide metabolism especially in memory process.
Acetylcholine↗
Molecular basis for Glanzmann's thrombasthenia (GT) in a compound heterozygote with glycoprotein IIb gene: a proposal for the classification of GT based on the biosynthetic pathway of glycoprotein IIb-IIIa complex.
The genetic basis for Glanzmann's thrombasthenia (GT) was elucidated on a compound heterozygote with glycoprotein (GP)IIb gene: an opal mutation at the end of exon 17 (CGA----TGA) results in only a trace amount of GPIIb mRNA, and a splicing mutation at the acceptor site of exon 26 (CAG----GAG) causes an in-frame, exon skipping process from exon 25 to 27. This aberrant transcript encodes a single-chain polypeptide characterized by a 42-amino acid deletion, which includes the proteolytic cleavage site(s) and a unique, proline-rich region at the location corresponding to the carboxyl-terminal of the normal GPIIb alpha-chain. These characteristics are shared by a previously reported defective GPIIb molecule, which is neither assembled with GPIIIa nor transported to the cellular surface. Despite its normal transcription level, expression of the present defective GPIIb molecule was significantly decreased (approximately 6% of the control level). Because the precursor GPIIb molecule is assembled with GPIIIa in the endoplasmic reticulum (ER) and its processing, as well as stability, is dependent on the GPIIIa subunit, the defective GPIIb molecule may be rapidly degraded by the intrinsic quality control system of the ER due to its inability to form a stable heterodimer complex as a consequence of its misfolded structure. Although we did not confirm that the GPIIIa genes of this individual were normal, GPIIIa may be secondarily decreased (approximately 11% of control), because a large part of it could not be complexed, making it vulnerable to proteolysis. To elucidate the molecular basis for GT, we propose here a classification of GT based on the biosynthetic pathway of the GPIIb-IIIa complex.
Base Sequence↗
Characterization of nucleotide sequences that interact with a nuclear protein fraction in rRNA gene of Vicia faba.
A certain nucleotide sequence in the promoter region of Vicia faba rRNA genes that specifically binds to a nuclear protein fraction has been identified by using a gel retardation assay and DNase I footprinting technique. The binding site of this protein fraction is located about 60 bp upstream from the initiation site of the pre-rRNA transcript. This location does not correspond with previously reported results on maize rRNA genes. However, both of the binding sites share a bi-partite consensus sequence, TAT-G(N)xCAGG. Methylation interference experiments show that two G residues in TATG and the complementary strand of CAGG are important for specific DNA-protein interaction. Furthermore, competition analyses using point-mutated synthetic DNAs show that two G residues in CAGG are essential for this interaction. Similar sequences are found in promoter regions of other plant and animal rRNA genes. We suggest that these sequences may be a cis-control element commonly involved in rRNA transcription.
Base Sequence↗
Monoclonal antibody GOM-2 binds to blood group B-Le(y) active glycolipid antigens on human gastric cancer cells, KATO-III.
The antigen structure of a mouse monoclonal antibody, GOM-2, established by immunization with KATO-III human gastric cancer cells, was examined. GOM-2 reactive glycolipids were prepared from KATO-III cells and treated with endoglycoceramidase. Structural studies of ten GOM-2 reactive oligosaccharides by a combination of glycosidase digestions, methylation, and affinity chromatography on an Ulex europeus agglutinin I (UEA-I) column revealed that nine of them had a Y-related B-active difucosylated determinant (B-Le(y)) and one had a B-active determinant. Affinity chromatography of the purified and modified oligosaccharides on an immobilized GOM-2 column demonstrated that GOM-2 has a novel binding specificity: it binds tightly to the biantennary structure carrying the B-Le(y) determinant at the termini or the branched structure carrying the B-Le(y) structure at two nonreducing termini.
Antibodies, Monoclonal↗
Synthesis and biodistribution of a fluorine-18 labeled analogue of D-talose: 2-deoxy-2-[18F]fluoro-D-talose.
A fluorine-18 labeled analogue of D-talose, 2-deoxy-2-[18F]fluoro-D-talose ([18F]FDT), was synthesized via nucleophilic fluorination with [18F]fluoride ion and its biodistributions in animals were examined. Radiofluorination of benzyl 3,5,6-tri-O-benzyl-2-O-(trifluoromethanesulfonyl)-alpha-D-galac tof uranoside (5) with aminopolyether supported potassium [18F]fluoride (K18F/Kry222) in acetonitrile followed by deprotection of the [18F]fluorinated intermediate (6) with boron tribromide in CH2Cl2 gave [18F]FDT in an average radiochemical yield of 29% with a radiochemical purity greater than 98%. Biodistribution studies of [18F]FDT in mice bearing fibrosarcoma showed the highest uptake of radioactivity in the liver (34.9% dose/g), followed by the kidney (15.9%dose/g), the small intestine (12.9%dose/g) and fibrosarcoma (5.7%dose/g), at 30 min after i.v. administration. Although the radioactivity in the kidney and small intestine decreased with time, the uptake in the liver and the tumor slightly increased until 120 min. The high liver uptake of [18F]FDT was also observed in normal rats and this uptake was strongly inhibited by co-administration of D-galactose. These preliminary results suggest that [18F]FDT might be metabolized through the galactose metabolic pathway as analogously observed with 2-deoxy-2-[18F]fluoro-D-galactose which is an isomer with respect to carbon-2 of [18F]FDT, and that it may be another candidate for studying liver function by positron emission tomography.
Animals↗
A case of Hallervorden-Spatz disease: progressive and intractable dystonia controlled by bilateral thalamotomy.
We present a 10-year-old girl with Hallervorden-Spatz disease diagnosed clinically from the neurological manifestations and the characteristic MRI findings. Her main symptom, dystonia, was progressive and resistant to medication, but this dystonia was controlled by bilateral thalamotomy. No clinical progression of the symptoms was recognized at 21 months from the last operation.
Child↗
Molecular characterization of cDNA encoding for adenylate kinase of rice (Oryza sativa L.).
Two types of genes (Adk-a, and Adk-b) encoding for adenylate kinase (AK, EC 2.7.4.3.) were isolated from the cDNA library constructed from poly(A)+ RNA of rice (Oryza sativa L.). Two cDNAs were heterogeneous at 5' and 3' ends of non-coding sequences and had possible polyadenylation signals. One of the genes, Adk-a, had 1154 bp sequences encoding 241 amino acid residues, while the other type, Adk-b, contained 1085 bp sequences encoding for 243 amino acid residues. Homology between Adk-a and Adk-b was 73.7% in nucleotide sequences, and 90.8% in amino acid level. Two genes showed about 53% homology to bovine mitochondrial adenylate kinase (AK2) at nucleotide and amino acid levels. Concerning the codon usage of rice AK genes, T was abundant at the third position of a codon in the reading frames. In order to examine the enzyme activity of the protein encoded by the rice cDNA, Adk-a was cloned into an expression vector, pUC119, which was introduced into Escherichia coli strain CV2, a temperature-sensitive mutant of adenylate kinase. We found that the transformant carrying the rice Adk-a gene in the sense orientation recovered cell growth at non-permissive high temperature (42 degrees C) and expressed enzyme activities higher than the untransformed CV2 and the transformant possessing Adk-a cDNA in the antisense orientation. These observations suggest that rice Adk-a codes a biologically active enzyme. Furthermore, sucrose was found to regulate the transcription of AK genes in rice cell cultures. Organ related accumulation of mRNA in whole plants was also found.
Adenylate Kinase↗
HIV-1 reverse transcriptase inhibitor from Phyllanthus niruri.
An aqueous extract of Phyllanthus niruri (Euphorbiaceae) inhibited human immunodeficiency virus type-1 reverse transcriptase (HIV-1-RT). The inhibitor against HIV-1-RT in this plant was purified by combination of three column chromatographies, Sephadex LH-20, cellulose, and reverse-phase high-performance liquid chromatography. The inhibitor was then identified by nuclear magnetic resonance (NMR) spectra as repandusinic acid A monosodium salt (RA) which was originally isolated from Mallotus repandus. The 50% inhibitory doses (ID50) of RA on HIV-1-RT and DNA polymerase alpha (from HeLa cells) were 0.05 microM and 0.6 microM, respectively, representing approximately a 10-fold more sensitivity of HIV-1-RT compared with DNA polymerase alpha. RA was shown to be a competitive inhibitor with respect to the template-primer while it was a noncompetitive inhibitor with respect to the substrate. RA as low as 10.1 microM inhibited HIV-1-induced cytopathogenicity in MT-4 cells. In addition, 4.5 microM of RA inhibited HIV-1-induced giant cell formation of SUP-T1 approximately 50%. RA (2.5 microM) inhibited up to 90% of HIV-1 specific p24 antigen production in a Clone H9 cell system.
Antigens, Viral↗
Establishment and characterization of monoclonal antibodies to carbohydrate antigens on peanut agglutinin receptor glycoprotein of gastric cancer KATO-III.
Eight mouse monoclonal antibodies, GOM-1, GOM-2, GOM-3, GOM-5, GOM-6, GOM-7, GOM-8 and GOM-9 were established that recognized carbohydrate antigens on the human gastric cancer cell line KATO-III. Their binding specificities were studied by enzyme-linked immunosorbent assay, cellular enzyme-linked immunosorbent assay, flow cytometry analysis and thin layer chromatography immunostaining. All these monoclonal antibodies bound to peanut agglutinin receptor glycoproteins and neutral glycolipids extracted from KATO-III cells, but they could be divided into three groups, namely GOM-1, -3, -9 group, GOM-5 and GOM-2, -6, -7, -8 group. GOM-3 specifically bound to the Le(a) structure, Gal beta 1-3 (Fuc alpha 1-4) GlcNAc beta 1-, and GOM-5 specifically bound to the Lec structure, Gal beta 1-3GlcNAc beta-. GOM-2 showed specific binding to KATO-III, but little or no binding to various other cell lines examined or to normal human leukocytic cells. It also did not bind to the synthetic glycoconjugates tested, carrying 10 different terminal sugar chains including T, Tn, Le(a), Lec and Le(x) structures. The binding specificity of GOM-2 was also different from those of the monoclonal antibodies anti-Le(x), anti-Leb and anti-Ley. These results suggest that GOM-2 recognizes a new carbohydrate antigen on KATO-III cells that is distinct from Le(a), Leb, Lec, Le(x), Ley, T and Tn structures.
Animals↗
Cytokine-related immunopotentiating activities of paramylon, a beta-(1-->3)-D-glucan from Euglena gracilis.
Paramylon, a beta-(1-->3)-D-glucan, isolated from Euglena gracilis, was tested for its adjuvant activity on the antibody response to sheep red blood cell (SRBC) in mice. Paramylon markedly enhanced anti-SRBC plaque-forming cell production at a dose of 10 mg/kg. It was also found that in vitro addition of lipopolysaccharide in culture to macrophages from paramylon-treated mice produced a large amount of interleukin 1 (IL-1) and there was a significant level of interleukin 6 (IL-6) induced transiently in the blood of these mice. As IL-1 and IL-6 play crucial roles in the immune response to T cell-dependent antigens like SRBC, the immunopotentiating effect of paramylon might be expressed through the action of these cytokines.
Adjuvants, Immunologic↗
Bactericidal action of lysozyme against gram-negative bacteria due to insertion of a hydrophobic pentapeptide into its C-terminus.
Explore the source record for details and available documents.
Amino Acid Sequence↗
Structural and functional properties of hen egg-white lysozyme deamidated by protein engineering.
The structural and functional properties of lysozymes genetically deamidated at positions 103 (N103D) and 106 (N106D) were studied by a protein engineering technique. The wild-type and mutant lysozymes were expressed in Saccharomyces cerevisiae and purified from the cultivation medium in two steps by cation-exchange chromatography on CM-Toyopearl. The lytic activity of deamidated lysozymes was almost the same as that of wild lysozyme, although the optimal pH of activity was slightly shifted to lower pH by the deamidation. The Gibbs free energy changes of unfolding (delta G) at 20 degrees C for N103D and N106D were almost the same as that of wild-type. On the other hand, the structural flexibility of lysozymes, estimated by protease digestion, was significantly increased by the deamidation. The surface functional properties of deamidated lysozymes were considerably enhanced, compared to those of wild-type lysozyme. These results suggest that structural flexibility is an important governing factor in surface functional properties of proteins, regardless of their structural stability.
Animals↗
Are there M cells in the cecal tonsil of chickens?
A unique morphological cell type, "microfold or membranous (M) cell-like cell", was detected electron-microscopically in the cecal tonsil epithelium of the chicken. M cell-like cells possessed a few short microvilli of irregular arrangement and a large number of lymphocytes and macrophages wedged into their basal surfaces. Triticum vulgaris was found to bind to M cell-like cells. With horseradish peroxidase (HRP) treatment, M cell-like cells showed an active HRP uptake just as did the neighbouring usual absorptive epithelial cells. No uptake of colloidal carbon particles from the intestinal lumen was recognized in any part of the intestinal epithelium. These results suggest that M cell-like cells of the chicken possess some M cell-characteristic morphological and histochemical features, but that their active uptake of foreign materials is not so developed as in mammalian M cells.
Animals↗
Factors affecting severity of renal injury and recovery of function in acute renal failure.
Severity of renal injury and recovery of function in acute renal failure (ARF) are strongly related not only to the magnitude and nature of ARF insult but also to numerous factors in the host which govern renal susceptibility to the insult and repair of renal lesion. Prior ARF affords resistance to a rechallenge with the same or different ARF insult. The mechanisms for this acquired resistance to ARF have not been well established, but suggested mechanisms include (a) increased resistance of regenerated tubular epithelial cells to a rechallenge, (b) glomerular refractoriness to vasoactive substances, (c) failure of damaged kidney to concentrate the toxic substance, (d) enhanced antioxidant enzyme activity in glomeruli, and (e) increased Na(+)-K(+)-ATPase activity in regenerated tubular epithelial cells. Controversy still exists regarding roles of these factors in the resistance to renal failure. Functional and morphologic recovery of postischemic kidney is enhanced by antecedent unilateral nephrectomy but delayed in the presence of the contralateral kidney. The mechanisms for the effect of uninephrectomy remain unsettled. Recent studies suggest contributions of changes in preglomerular vascular resistance; alterations in the environment which follow ischemia to all functioning excretory renal tissues; and altered production and release of vasoactive substances such as angiotensin, endothelin, thromboxane, and atrial natriuretic peptide.
Acute Kidney Injury↗