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Biomedical subjects

S Ueno

Publications and source records attributed to S Ueno.

At least 253 records · Page 14Linked to original sources
PubMed1993

Structural study of the N-linked oligosaccharides of hepatocyte growth factor by two-dimensional sugar mapping.

The structures of the N-linked oligosaccharides on recombinant human hepatocyte growth factor (rh-HGF) expressed by Chinese hamster ovary (CHO) cells were studied by two-dimensional sugar mapping. The oligosaccharides released from the glycopeptides by peptide: N-glycosidase F (PNGase F) treatment were tagged with 2-aminopyridine at the reducing ends. The alpha-chain was linked by biantennary, triantennary, and tetraantennary oligosaccharides, but the dominant oligosaccharides linking the beta-chain were biantennary (> 85%). There was no significant difference in oligosaccharide structures between the two glycosylation sites on each chain, that is, Asn263 and Asn371 on the alpha-chain, and Asn535 and Asn622 on the beta-chain. The linkage of sialic acid to the non-reducing terminal galactose was identified as NeuAc alpha(2-3) by 1H-NMR spectrometry. The structures of the N-linked oligosaccharides from rat HGF were also studied. Triantennary oligosaccharides were obtained from the alpha-chain and a biantennary oligosaccharide was obtained from the beta-chain. This result indicates that the alpha-chain is also linked by higher branched oligosaccharides than the beta-chain in rat HGF.

Aminopyridines↗
PubMed1993

A gradient system solution to Potts mean field equations and its electronic implementation.

A gradient system solution method is presented for solving Potts mean field equations for combinatorial optimization problems subject to winner-take-all constraints. In the proposed solution method the optimum solution is searched by using gradient descent differential equations whose trajectory is confined within the feasible solution space of optimization problems. This gradient system is proven theoretically to always produce a legal local optimum solution of combinatorial optimization problems. An elementary analog electronic circuit implementing the presented method is designed on the basis of current-mode subthreshold MOS technologies. The core constituent of the circuit is the winner-take-all circuit developed by Lazzaro et al. Correct functioning of the presented circuit is exemplified with simulations of the circuits implementing the scheme for solving the shortest path problems.

Algorithms↗
PubMed1993

Hyperechoic renal tumors: anechoic rim and intratumoral cysts in US differentiation of renal cell carcinoma from angiomyolipoma.

To determine whether angiomyolipomas (AMLs) and renal cell carcinomas (RCCs) can be differentiated at ultrasonography (US), the authors retrospectively evaluated the sonographic appearances of 31 AMLs and 38 RCCs. Sonograms were evaluated by three radiologists without knowledge of histologic findings, with respect to the echogenicity of the tumor, predominant echotexture, and whether an anechoic rim was present. All patients had also undergone computed tomography (CT) to check for tumoral fat. Intratumoral fat was evident at CT in 28 of the 31 AMLs. RCCs had no fat at CT or histologic evaluation. An anechoic rim was evident in 32 of 38 (84%) RCCs, and 10 RCCs had small anechoic areas with back echo enhancement, which corresponded to intratumoral cysts or cystic necrosis at histologic evaluation. The anechoic rim and areas indicative of cysts were not found in AMLs. Demonstration of an anechoic rim and/or intratumoral cysts in a hyperechoic mass at US suggests that the tumor is an RCC.

Adult↗
PubMed1993

Serotonin-operated potassium current in CA1 neurons dissociated from rat hippocampus.

1. The intracellular mechanisms of serotonin (5-HT) response were investigated in dissociated rat hippocampal pyramidal neurons using the nystatin-perforated patch technique. 2. Under voltage-clamp conditions, 5-HT evoked outward currents (I5-HT) with an increase in membrane conductance at a holding potential of -40 mV. The outward current reversed at the K+ equilibrium potential, which shifted 59.4 mV with a 10-fold change in extracellular K+ concentration. 3. The first application of 5-HT on neurons perfused with Ca(2+)-free external solution induced outward currents of I5-HT but the amplitude was diminished dramatically with successive applications. Pretreatment with the membrane-permeant Ca2+ chelator 1,2-bis-(O-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid, tetraacetoxymethyl ester (BAPTA-AM) also diminished the I5-HT amplitude. 4. Pretreatment with pertussis toxin (PTX) had no effect on I5-HT. 5. The I5-HT was not cross-desensitized with the caffeine-induced outward current but with outward current mediated by the muscarinic acetylcholine receptor. Pretreatment with Li+ significantly enhanced the I5-HT, indicating that I5-HT is involved in the elevation of intracellular free Ca2+ released from inositol triphosphate (IP3)-sensitive Ca2+ store sites but not from the caffeine-sensitive ones. 6. The calmodulin (CaM) antagonists, trifluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), inhibited I5-HT in a concentration-dependent manner. 7. The Ca2+/CaM-dependent protein kinase II inhibitor 1-[N,O-Bis (5-isoquinolinesulfonyl)-N-methyl-L-tyrosil]-4-phenylpiperazine depressed the I5-HT.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Use of cultured human epidermal allografts for the treatment of extensive partial thickness scald burn in children.

In spite of recent progress in burn treatment, the early surgical therapy of partial thickness scald burns in children is still controversial. Early tangential excisions is not easily applicable for these patients because of difficulties in determination of the burn depth and probable physiological derangement after surgery. Hypertrophic scar formation and wound contraction after meshed autografts are other limitations. For these reasons, conservative treatment, not early excision therapy, has been chosen initially for these injuries. We used cultured epidermal allografts for extensive, partial thickness scald burns, during the early post-burn period without escharectomy. Fifty to 100% of the engrafted superficial dermal burns were epithelialized within 7 days. In contrast, untreated identical wounds remained open. Repeated grafting of cultured allografts on unexcised wound granulations of dermal burns also enhanced epithelialization. Long term results showed that hypertrophic scar formation in the mixed superficial and deep dermal burns was reduced when cultured allografts were used. Allografting of the cultured epidermis without surgical excision apparently promoted the rapid regeneration of the partial thickness burns. Procedural complications did not occur. Cultured allografts should be used as an effective and safe biological dressing for partial thickness scald burns in children.

Burns↗
PubMed1993

[Deletions of mitochondrial DNA in Kearns-Sayre syndrome].

Single large-scale deletions of mitochondrial DNA (mtDNA) are found in 70 to 80% of Kearns-Sayre syndrome (KSS) patients. Most deletions are flanked by direct repeats up to 13 nucleotides in length. The incidence of ragged-red fibers and cytochrome c oxidase-negative fibers in muscle is correlate with the amount of deleted mtDNA. Recently, study with 'cybrid' cell lines, which have different proportions of deleted mtDNA, showed that accumulation of deleted mtDNA to over 60% of the total mtDNA resulted in progressive inhibition of overall mitochondrial translation, as well as, reduction of cytochrome c oxidase activity. These results suggest that deletion of mtDNA alone is sufficient for the mitochondrial dysfunction in KSS.

Adult↗
PubMed1993

[Clinical and genetic heterogeneity in familial amyloidotic polyneuropathy associated with variant transthyretin].

Familial amyloid polyneuropathy (FAP) is an autosomal disease, usually associated with a variant of transthyretin (TTR). To date, about 30 variants of TTR have been described in FAP. Clinical heterogeneity regarding age of onset and organ involvement exists in TTR-related FAP. The age of onset in patients with TTR-Met 30 variant ranges from the third to the seventh decade. The pattern of peripheral neuropathy varies considerably. Lower limb neuropathy is the common mode in cases with Met 30 and other many variants of TTR, while in some cases, upper limb neuropathy with carpal tunnel syndrome is the most important feature. The presence of vitreous opacity is one of the cardinal manifestations in several kindreds (eg. Cys 114, lle 33). The mechanism by which variant TTR affects clinical heterogeneity in FAP is unknown and deserves future study.

Adult↗
PubMed1992

Effects of Ca2+ antagonists and antiepileptics on tetrodotoxin-sensitive Ca(2+)-conducting channels in isolated rat hippocampal CA1 neurons.

All Ca2+ antagonists blocked tetrodotoxin-sensitive Ca2+ current (TTX-ICa) more potently than Na+ current (INa). Phenytoin and MK-801, at concentrations which had no effect on INa, could block TTX-ICa concentration-dependently. Valproic acid and phenobarbital had no effect on both TTX-ICa and INa. In particular, flunarizine and phenytoin have more potent inhibitory effects on TTX-ICa than other test drugs. These results suggest that the abnormal excess-excitation of TTX-sensitive Ca(2+)-conducting channels may be one of the trigger factors generating epilepsy.

Animals↗
PubMed1992

Human peripheral blood lymphocytes express D5 dopamine receptor gene and transcribe the two pseudogenes.

Sequential reverse transcription and polymerase chain reaction (RT-PCR) of the mRNA were used to investigate the expression of dopamine receptors in human peripheral blood lymphocytes. The RT-PCR products contained three types of sequences, each corresponding to those of the D5 dopamine receptor gene and the two related pseudogenes. The lymphocyte cDNA library also contained the clones encoding parts of the three genes. Binding profiles of dopaminergic ligands to the lymphocytes were similar to those for the native neuronal membranes.

Benzazepines↗
PubMed1992

Perforated-patch method reveals extracellular ATP-induced K+ conductance in dissociated rat nucleus solitarii neurons.

Extracellular adenosine 5'-triphosphate (ATP)-induced responses were investigated in acutely dissociated rat nucleus tractus solitarii (NTS) neurons, using nystatin perforated-patch and conventional whole-cell patch-clamp recordings. Extracellular application of ATP could evoke the inward currents with both methods. An additional outward current was observed only with the perforated patch method. The outward current resulted in an increase of K+ conductance which was activated by Ca2+ influx through the ATP receptor-channel complex.

Adenosine Triphosphate↗
PubMed1992

[Intracranial MR imaging of achondroplasia].

Intracranial MR imaging was performed in five patients with achondroplasia. All patients had narrowing of the subarachnoid space at the level of the foramen magnum that was mainly due to protrusion of the posterior aspect. Three patients had compressive deformities of the brainstem and/or upper cervical spine. Among them, two patients had deformities of the pons. Relative upward displacement of the brainstem was seen in all patients. Hydrocephalus was seen in three patients.

Achondroplasia↗
PubMed1992

A novel mutant (transthyretin Ile-50) related to amyloid polyneuropathy. Single-strand conformation polymorphism as a new genetic marker.

DNA sequence polymorphisms in transthyretin (TTR) genes were investigated by single-strand conformation polymorphism (SSCP) analysis of polymerase chain reaction products. The amplified DNA fragments that encode each exon of the normal TTR gene showed two bands, representing the two complementary single strands of DNA. In one patient with amyloid polyneuropathy, the exon 3 DNA showed a unique, aberrant migration pattern. Direct sequencing analysis of the amplified exon 3 revealed a single base change (G-to-T), resulting in a novel amino acid substitution (Ser-50----Ile). We also present the SSCP patterns for five known Japanese TTR variants.

Amyloidosis↗
PubMed1992

Saposin-C from bovine spleen; complete amino acid sequence and relation between the structure and its biological activity.

Saposin-C, a small acidic glycoprotein that can activate glucosylceramide-beta-glucosidase, has been isolated from bovine spleen. The complete amino acid sequence of bovine saposin-C was determined by Edman degradation of the purified protein and its fragmented peptides. It contains 80 amino acids, one carbohydrate chain attached to a single asparagine residue and six cysteine residues in oxidized form. The sequence of bovine saposin-C is 76 and 65% identical with the sequences of saposin-C from human spleen and guinea pig liver, respectively. Hydropathy profiles of the sequence of saposin-C from three species were similar despite the significant residue substitutions. Bovine saposin-C had a stronger effect in stimulating bovine beta-glucosidase compared to human saposin-C. However, the effect of human saposin-C in stimulating human enzyme was stronger than that of bovine saposin-C. The region around residue 35, which is next to the extremely hydrophilic region, seems to be important to produce an interaction with the enzyme.

Amino Acid Sequence↗
PubMed1992

Methylated cytosine level in human liver DNA does not decline in aging process.

In order to ascertain a generality of the age-dependent decrease in DNA methylation level among different mammalian species, methylated cytosine contents in human liver and spleen DNA at different ages have been determined using high performance liquid chromatography (HPLC). Unexpectedly, the liver DNA revealed no appreciable decline with age while the spleen DNA showed a slight reduction. It indicates that a decrease of methylation level in genomic DNA is not a common denominator of age-related changes in mammals.

Adolescent↗
PubMed1992

GABAergic synaptic current in dissociated nucleus basalis of Meynert neurons of the rat.

gamma-Aminobutyric acid (GABA)-mediated spontaneous inhibitory postsynaptic currents (IPSCs) were recorded from dissociated rat nucleus basalis of Meynert neurons which still had their synaptic boutons attached. The membrane currents were recorded by the whole-cell patch-clamp technique. Elevated extracellular K+ concentration and the addition of the calcium ionophore, A23187, enhanced the amplitude and frequency of spontaneous IPSCs. Ryanodine and Ca(2+)-free external solution containing EGTA or BAPTA markedly decreased the spontaneous IPSC activities. Spontaneous IPSC activities were reversibly reduced by baclofen and increased by phaclofen, indicating that the GABAB receptor regulates the release of GABA from nerve terminals and acts as a negative autoreceptor.

Animals↗