Biomedical subjects

A Chiba

Publications and source records attributed to A Chiba.

At least 73 records · Page 4Linked to original sources

PubMed1997

Structures of sialylated O-linked oligosaccharides of bovine peripheral nerve alpha-dystroglycan. The role of a novel O-mannosyl-type oligosaccharide in the binding of alpha-dystroglycan with laminin.

alpha-Dystroglycan is a heavily glycosylated protein, which is localized on the Schwann cell membrane as well as the sarcolemma, and links the transmembrane protein beta-dystroglycan to laminin in the extracellular matrix. We have shown previously that sialidase treatment, but not N-glycanase treatment, of bovine peripheral nerve alpha-dystroglycan greatly reduces its binding activity to laminin, suggesting that the sialic acid of O-glycosidically-linked oligosaccharides may be essential for this binding. In this report, we analyzed the structures of the sialylated O-linked oligosaccharides of bovine peripheral nerve alpha-dystroglycan by two methods. O-Glycosidically-linked oligosaccharides were liberated by alkaline-borotritide treatment or by mild hydrazinolysis followed by 2-aminobenzamide-derivatization. Acidic fractions obtained by anion exchange column chromatography that eluted at a position corresponding to monosialylated oligosaccharides were converted to neutral oligosaccharides by exhaustive sialidase digestion. The sialidases from Arthrobacter ureafaciens and from Newcastle disease virus resulted in the same degree of hydrolysis. The neutral oligosaccharide fraction, thus obtained, gave a major peak with a mobility of 3.8-3.9 glucose units upon gel filtration, and its reducing terminus was identified as a mannose derivative. Based on the results of sequential exoglycosidase digestion, lectin column chromatography, and reversed-phase high-performance liquid chromatography, we concluded that the major sialylated O-glycosidically-linked oligosaccharide of the alpha-dystroglycan was a novel O-mannosyl-type oligosaccharide, the structure of which was Siaalpha2-3Galbeta1-4GlcNAcbeta1-2Man-Ser/Thr (where Sia is sialic acid). This oligosaccharide constituted at least 66% of the sialylated O-linked sugar chains. Furthermore, a laminin binding inhibition study suggested that the sialyl N-acetyllactosamine moiety of this sugar chain was involved in the interaction of the alpha-dystroglycan with laminin.

Animals↗

PubMed1997

Ganglioside composition of the human cranial nerves, with special reference to pathophysiology of Miller Fisher syndrome.

Total ganglioside fractions from the human cranial nerves purified on a Phenyl Sepharose column, were given mild alkaline treatment, after which their composition and amounts of lipid-bound sialic acid were determined by HPTLC-densitometry with resorcinol as the coloring reagent. The total amounts of lipid-bound sialic acid were 156.5 ng/mg of wet tissue in the Ist cranial nerve (olfactory tract) and 131.9 ng/mg in the IInd nerve, greater than the amounts in the other nerves (99.1-120.0 ng/mg). The Ist, IInd, and VIIIth nerves had GM4, but not LM1. It may reflect their histological feature of the central nervous system. The IIIrd, IVth, and VIth nerves, as well as the IInd, had significantly higher percentages of GQ1b (11.6-13.2%) than the other nerves (5.2-8.4%). The high proportion of GQ1b specific to these three cranial nerves involved in the ocular movement lends support to the role of serum anti-GQ1b antibody in the pathogenetic mechanisms of ophthalmoplegia in Miller Fisher syndrome and Guillain-Barré syndrome.

Aged↗

PubMed1997

Antimutagenicity of Tochu tea (an aqueous extract of Eucommia ulmoides leaves): 1. The clastogen-suppressing effects of Tochu tea in CHO cells and mice.

The suppressing effect of crude extracts of Tochu tea, an aqueous extract of Eucommia ulmoides leaves and a popular beverage in Japan, on the induction of chromosome aberrations in CHO cells and mice was studied. When CHO cells were treated with Tochu tea crude extract after MMC treatment, the frequency of chromosome aberrations was reduced. Out of 17 Tochu tea components, 5 irridoids (geniposidic acid, geniposide, asperulosidic acid, deacetyl asperulosidic acid, and asperuloside) and 3 phenols (pyrogallol, protocatechuic acid, and p-trans-coumaric acid) were found to have anticlastogenic activity. Since the anticlastogenic irridoids had an alpha-unsaturated carbonyl group, this structure was considered to play an important role in the anticlastogenicity. The anticlastogenic effect of Tochu tea extracts was examined in mice using a micronucleus assay. When mice received 1.0 ml 4% Tochu tea extract by oral gavage 6 h before intraperitoneal injection of MMC, a decrease in the frequency of micronuclei was observed. This decrease was not due to a delay in the maturation of micronucleated reticulocytes.

Animals↗

PubMed1997

Ultrastructural study of the keratinization of the dorsal epithelium of the tongue of Middendorff's bean goose, Anser fabalis middendorffii (Anseres, Antidae).

BACKGROUND: Comparative studies of ultrastructural features of tongues allow deductions to be made about relationships between structure and function, as reflected by an animal's feeding habits. The present study was performed to serve as a basis for further studies of avian feeding mechanisms and of relationships between the fine structure of the lingual epithelium and the development of the expression of keratins. METHODS: The light microscope, scanning electron microscope, and transmission electron microscope were used. RESULTS: The dorsal surface of the tongue of Middendorff's bean goose, Anser fabalis middendorffii, has a distinctive anterior region that extends for five-sixths of its length and has a clear posterior region. The anterior region, when observed macroscopically and by scanning electron microscopy, is distinguished along its forward half by a clear median line. The back half of the anterior region has an indistinct median sulcus in some parts. There are no lingual papillae on the entire dorsal surface of the anterior and posterior regions. Giant conical papillae are located in a transverse row between the anterior and posterior regions. On both lateral sides of the anterior region for five-sixths of the length of the tongue, lingual hairs are compactly distributed, and small numbers of large cylindrical papillae are arranged at almost regular intervals between these lingual hairs. Examination of the dorsal lingual epithelium by light and transmission electron microscopy provided histological and cytological criteria for distinguishing the anterior and posterior regions, both of which were composed of stratified squamous epithelium. Basal cells were similar throughout the dorsal epithelium. The intermediate layer of cells in the anterior region contained numerous tonofibrils in electron-dense bundles composed of tonofilaments of 10 nm in diameter. The outer layer was composed of electron-dense, well-keratinized cells, with layers of electron-lucent cells on the outermost surface. The cells in the intermediate layer in the posterior region of the tongue were almost completely filled with unbundled tonofilaments. The surface layer exhibited features of parakeratinization. In all of the giant conical papillae, the large cylindrical papillae, and the lingual hairs, the epithelium was strongly keratinized. CONCLUSIONS: The three-dimensional microanatomy and cytological features of the dorsal lingual epithelium of avians seem to be related to the functional role and shape of the tongue of each species in feeding.

Age Factors↗

PubMed1997

Binding of antibodies against GM1 and GD1b in human peripheral nerve.

Human dorsal root ganglia (DRG), and ventral and dorsal roots were immunostained with rabbit antibodies recognizing GM1, GD1b, or both. Sera from rabbits immunized with GM1 or GD1b were separated in affinity columns into three fractions: Rab1, Rab2, and Rab3. Rab1 recognized only GM1, and Rab2 only GD1b; whereas Rab3 recognized both GM1 and GD1b, presumably by binding to the terminal galactosyl beta 1-3N-acetylgalactosaminyl residue. Rab2 and Rab3 immunostained most of the nerve cell bodies in the DRG and paranodal myelin of the ventral and dorsal roots, whereas Rab1 produced no significant immunostaining. These results show that GD1b is localized on the DRG neurons and the paranodal myelin of human peripheral nerve. These places may be the binding sites for anti-GD1b antibodies, including those cross-reactive with GM1, in the sera from patients with autoimmune neuropathies. GM1 may be dispersed in human DRG and dorsal and ventral roots.

Animals↗

PubMed1997

Distribution of neuropeptide Y-like immunoreactivity in the brain of the bichir, Polypterus senegalus, with special regard to the terminal nerve.

The distribution of neuropeptide Y (NPY)-like immunoreactivity in the brain of the bichir, Polypterus senegalus, was examined immunohistochemically. NPY-like immunoreactivity was distributed widely in the brain, with the highest density in the diencephalon. NPY-positive perikarya were found in various areas, including the terminal nerve, the pallial zones of the telencephalon, the periventricular preoptic nucleus, the thalamic nucleus, the ventral hypothalamus of the diencephalon, the tegmentum of the mesencephalon, and the area intermedioventralis of the rhombencephalon. In the hypothalamus, NPY-positive liquor-contacting neurons were frequently observed. Immunoreactive neuron-like cells also appeared in the distal lobe of the hypophysis. NPY fibers were densely distributed in the ventral telencephalon, the hypothalamus, and the ventrolateral area of the rhombencephalon. They were also demonstrated in the terminal nerve. In the hypophysis, NPY fibers were dense in the median eminence, but sparse in the neural lobe. Electron-microscopic double immunostaining of the terminal nerve revealed the coexistence of NPY-like antigen with gonadotropin-releasing hormone-like and molluscan cardioexcitatory tetrapeptide-like antigens in the same cytoplasmic granules. These results suggest that NPY or a related substance is involved in neuroregulation of various areas of the bichir brain, by mainly acting as a neurotransmitter or neuromodulator.

Animals↗

PubMed1997

Analysis of the non-sense mutants of varicella-zoster virus thymidine kinase.

Three non-sense mutants of varicella-zoster virus (VZV) thymidine kinase (TK) gene, VZTK325, VZTK278 and VZTK224, were isolated. The mutants had a single nucleotide substitution at codons 326, 279 and 225, which changed the codon of TGG (tryptophan) to the stop codon TGA. The wild type (WT) and mutant TKs were expressed in E. coli cells and their characteristics were evaluated. VZTK224 lost TK activity, but VZTK325 and VZTK278 maintained 74.8% and 21.2% of the WT TK activity. On the other hand, all mutants lost the thymidylate kinase activity. Moreover, VZTK325 and VZTK278 polypeptides were heat-labile. These data suggest that the carboxy-terminal portion of herpesvirus TK plays an important role in the stable folding of TK and thymidylate kinase activity.

Heating↗

PubMed1997

Melatonin inhibits naloxone-induced luteinizing hormone release in ovariectomized estrogen-primed rats.

The present study aimed to examine the effect of melatonin on naloxone-induced luteinizing hormone (LH) secretion in ovariectomized estrogen-primed rats. A single intracerebroventricular (i.c.v.) injection of naloxone (mu opioid receptor blocker, 15 micrograms) or an intravenous (i.v.) injection of LH-releasing hormone (LHRH, 50 ng/kg) elicited a transient and significant increase in the serum LH concentration within 10 min. While an i.c.v. injection of 100 ng melatonin by itself did not change the basal LH release, it almost completely inhibited the naloxone-induced LH release. Melatonin (10 ng) also significantly reduced the effect of naloxone. However, an i.c.v. injection of 100 ng melatonin did not affect the LHRH-induced LH release. In separate experiments, the effect of melatonin on naloxone-induced pulsatile LH secretion was studied in estrogen-treated rats. A continuous i.v. infusion of naloxone (20 mg/kg/h) induced LH pulses in rats treated i.c.v. with saline. An i.c.v. administration of 100 ng melatonin, which by itself did not affect basal LH secretion, significantly reduced the frequency, but not the amplitude, of LH pulses induced by the naloxone infusion. These results show that melatonin has a suprapituitary site of action to inhibit naloxone-induced LH release, and suggest that melatonin has an effect in inhibiting the activity of the hypothalamic LHRH pulse generator, either directly or indirectly, in female rats.

Animals↗

PubMed1997

Studies on the site of renal tubular defect in Bartter's syndrome.

Renal tubular function was studied in an 8-month-old male infant with Bartter's syndrome, which is characterized by hypokalemic metabolic alkalosis, normotensive hyperreninemic hyperaldosteronism, and reduced pressor response to angiotensin II. Chloride transport along the diluting segment (CH2O/CH2O + CCl) was impaired. Furthermore, furosemide did not elicit normal natriuresis, which suggested impaired chloride reabsorptive capacity at the furosemide-sensitive ascending limb of Henle's loop. Loss of antidiuretic hormone-mediated urinary concentration was in support of this. These findings pointed to the thick ascending limb of Henle's loop as the site of the primary defect in this child.

Bartter Syndrome↗

PubMed1997

Effect of indirect moxibustion on mouse skin.

Effect of indirect moxibustion stimulation on mouse skin was studied by thermal qualitative, biochemical, and histological methods. The maximum temperature change by indirect moxibustion was about 65 degrees C on the skin, and 45 degrees C in the subcutaneous layer. The treatment of indirect moxibustion was found to be associated with the decrease of lipid peroxidation and increase of superoxide dismutase (SOD) in the skin. Histological findings after indirect moxibustion showed an increase in the number of hair mother cells and hypertropy of the cells.

Animals↗

PubMed1997

Thermal and antiradical properties of indirect moxibustion.

The thermal and antiradical properties of indirect moxibustion stimulation were investigated by thermal qualitative and spectroscopic methods. The thermal effect of indirect moxibustion was mainly dependent on the spacing distance between the moxa and skin, and not on the moxa weight. The radical scavenging activities of moxa and moxa-tar were measured by a photometric absorbance method, chemical reaction with 1,1-diphenyl-2-picrylhydrazyl. The obtained results indicate that the inhibitory effects of moxa and moxa-tar on superoxide production are due to the radical scavenging mechanism.

Analysis of Variance↗

PubMed1997

Differential inhibition of NMDA- and naloxone-induced LH release by NMDA receptor antagonist and CRH in ovariectomized estrogen-primed rats.

A possible functional relationship between endogenous opioid peptides (EOPs), corticotropin-releasing hormone (CRH) and excitatory amino acids (EAAs) in the control of LH secretion was investigated in ovariectomized estrogen-primed rats. An intraventricular (icv) injection of an EAA agonist, N-methyl-D-aspartate (NMDA), or an EOP antagonist, naloxone, produced an abrupt increase in the serum LH level. While icv pretreatment of the animals with 2-amino-5-phosphonovaleric acid, a specific NMDA receptor antagonist, did not affect by itself basal LH levels, it significantly suppressed the NMDA-induced and also the naloxone-induced LH release. An icv injection of CRH also interfered with the naloxone-induced LH release. However, the NMDA-induced LH release was not affected by an icv injection of CRH or of beta-endorphin. These results suggest that the sites of EOP and CRH inhibition may be located upstream of the site of NMDA stimulation on the GnRH neuronal pathway, and that CRH can inhibit LH secretion without mediation by EOP neurons.

2-Amino-5-phosphonovalerate↗

PubMed1997

Homophilic synaptic target recognition mediated by immunoglobulin-like cell adhesion molecule Fasciclin III.

We demonstrate that the cell adhesion molecule Fasciclin III (FAS3) mediates synaptic target recognition through homophilic interaction. FAS3 is expressed by the RP3 motoneuron and its target muscles during synaptic target recognition. The RP3 growth cone can form synapses on muscles that ectopically express FAS3. This mistargeting is dependent on FAS3 expression in the motoneurons. In addition, when the FAS3-negative aCC and SNa motoneuron growth cones ectopically express FAS3, they gain the ability to recognize FAS3-expressing muscles as alternative targets. We propose that homophilic synaptic target recognition serves as a basic mechanism of neural network formation.

Animals↗

PubMed1997

Toll, a muscle cell surface molecule, locally inhibits synaptic initiation of the RP3 motoneuron growth cone in Drosophila.

Toll, a transmembrane molecule with extracellular leucine-rich repeats, is dynamically expressed by the Drosophila embryonic musculature. Growth cones of RP3 and other motoneurons normally grow past Toll-positive muscle cells and innervate more distal muscle cells, which have down-regulated their Toll expression. In this study, we show that reciprocal genetic manipulations of Toll proteins can produce reciprocal RP3 phenotypes. In Toll null mutants, the RP3 growth cone sometimes innervates incorrect muscle cells, including those that are normally Toll-positive. In contrast, heterochronic misexpression of Toll in the musculature leads to the same growth cone reaching its correct target region but delaying synaptic initiation. We propose that Toll acts locally to inhibit synaptogenesis of specific motoneuron growth cones and that both temporal and spatial control of Toll expression is crucial for its role in development.

Animals↗

PubMed1996

Antimutagenicity of Tochu tea (an aqueous extract of Eucommia ulmoides leaves): 2. Suppressing effect of Tochu tea on the urine mutagenicity after ingestion of raw fish and cooked beef.

The effect of Tochu tea, which is an aqueous extract of Eucommia ulmoides leaves and a popular-beverage in Japan, on the urine mutagenicity before and after ingestion of raw fish and cooked beef was studied using Salmonella typhimurium YG1024. Urines were collected from seven healthy, non-smoking Japanese women before and after ingestion of raw fish and cooked beef. In experiment 1,3 were in a control group and 4 were in a Tochu tea-drinking group (2000 ml per day). The mutagenicity of urine from the Tochu tea-drinking group was much lower. In experiment 2 the 7 women switched groups; the tea-drinking group became the control group, and the control group became the Tochu tea-drinking group. Again, the mutagenicity of urine collected from the Tochu tea-drinking group was much lower. These results suggest that the decrease in the mutagenicity of the urine from the Tochu tea-drinking group was due to the intake of Tochu tea, but not to individual differences. Thus, the ingestion of Tochu tea may reduce human exposure to dietary mutagens.

Adult↗

PubMed1996

Neuronal pathfinding and recognition: roles of cell adhesion molecules.

Neurons contact their neighbors through a diverse array of cell adhesion and other surface molecules. These molecules can exhibit highly regulated patterns of expression, underscoring their multiple roles in establishing specific interactions between neurons and their environment. Recent studies are beginning to ask how these membrane-bound neural recognition molecules interact with each other and intracellular signaling pathways within an individual neuronal growth cone, and direct the formation of neural connections during development.

Animals↗

PubMed1996

Ontogenetic changes in neuropeptide Y-like-immunoreactivity in the terminal nerve of the chum salmon and the cloudy dogfish, with special reference to colocalization with gonadotropin-releasing hormone-immunoreactivity.

We observed ontogenetic changes of neuropeptide Y (NPY)-like-immunoreactivity in the terminal nerve (TN) of the chum salmon, a teleost, and the cloudy dogfish, an elasmobranch. In the chum salmon, NPY-like-immunoreactive (NPY-IR) cells first appeared in the olfactory placode of embryos at 16 days after fertilization, and then extended sequentially and centrally in the olfactory system. Colocalization of NPY- and gonadotropin-releasing hormone (GnRH)-like-immunoreactivities was also observed in TN ganglion cells. In the cloudy dogfish, NPY-IR cells first appeared in the rudimental TN ganglion of the embryo at the 40 mm stage. Then, the NPY-IR cells and fibers in the TN system increased in density during late embryonic periods. Colocalization of NPY- and GnRH-like-immunoreactivities in TN ganglion cells was not found in the developing or the adult dogfish.

Age Factors↗

PubMed1996

Selection in vitro of trans-acting genomic human hepatitis delta virus (HDV) ribozymes.

In an effort to identify the functional structure as well as new active variants of the trans-acting genomic ribozyme of human hepatitis delta virus (HDV), we applied an in vitro selection procedure. A total of 14 rounds of selection and amplification was repeated and various mutant ribozymes in G10 and G14 pools analyzed. Active ribozymes which were isolated in the present study (from G10 and G14) all possessed conserved bases (that were identified earlier) in the cis-acting molecule. A dominant clone G10-68 variant was accumulated in generation 14. Interestingly, when base substitutions were analyzed in G10-68 variant, we found that this variant appears to be close to antigenome-like HDV ribozyme molecule. Further investigations of G10-68 confirmed that each mutated base was the most appropriate nucleotide at every position of the HDV ribozyme.

Base Sequence↗