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Biomedical subjects

S Yamaguchi

Publications and source records attributed to S Yamaguchi.

At least 307 records · Page 17Linked to original sources
PubMed1999

The ethanol metabolite acetaldehyde inhibits the induction of long-term potentiation in the rat dentate gyrus in vivo.

1. Ethanol has been reported to inhibit the induction of long-term potentiation (LTP) in the hippocampus. However, the correlation between the effects of ethanol in vivo and in vitro remained unclear. In addition, previous works have little considered the possibility that the effect of ethanol is mediated by its metabolites. To solve these problems, we investigated the effects of ethanol and acetaldehyde, the first metabolite in the metabolism of ethanol, on the induction of LTP at medial perforant path-granule cell synapses in the dentate gyrus of anaesthetized rats in vivo. 2. Oral administration of 1 g kg-1 ethanol significantly inhibited the induction of LTP, confirming the effectiveness of ethanol in vivo. 3. A lower dose of ethanol (0.5 g kg-1) failed to inhibit the induction of LTP in intact rats, but significantly inhibited LTP in rats treated with disulfiram, an inhibitor of aldehyde dehydrogenase, demonstrating that LTP is inhibited by acetaldehyde accumulation following ethanol administration. 4. Intravenous injection of acetaldehyde (0.06 g kg-1) significantly inhibited the induction of LTP. 5. The inhibitory effect of acetaldehyde on LTP induction was also observed when it was injected into the cerebroventricules, suggesting that acetaldehyde has a direct effect on the brain. The intracerebroventricular dose of acetaldehyde effective in inhibiting LTP induction (0.1 - 0.15 mg brain-1) was approximately 10 fold lower than that of ethanol (1.0 - 1.5 mg brain-1). 6. It is possible that acetaldehyde is partly responsible for memory impairments induced by ethanol intoxication.

Acetaldehyde↗
PubMed1999

Expression of inducible nitric oxide synthase (NOS) in bone marrow cells of myelodysplastic syndromes.

Nitric oxide (NO) is a biological mediator which is synthesized from L-arginine by a family of nitric oxide synthases (NOS). We have studied the expression of the inducible NOS (iNOS) by bone marrow cells from the patients with myelodysplastic syndromes (MDS) at the mRNA level by RT-PCR assay and at the protein level by immunohistochemical staining using a specific anti-iNOS monoclonal antibody. The iNOS message was present in 92% of bone marrow tissues from MDS patients (11 out of 12) by an examination using RT-PCR. Basically, iNOS message was negative or very weak in control (1/9) and AML (0/7) cases. This was supported by immunohistochemical findings that the iNOS was positive in most of the bone marrow samples from MDS patients (9 out of 12), while bone marrow cells of control (O out of 12) and AML (O out of 5) cases were basically negative. Double immunostaining for CD68 antigen, which is a marker for macrophage lineage cells, and iNOS was performed on MDS bone marrow sections. iNOS was dominantly localized to bone marrow macrophages, although a part of myeloid cells were also positively stained with anti-iNOS antibody in a part of cases. These results indicated that there is some in vivo induction of iNOS expression for local NO production that might be involved in the dysregulation of hematopoiesis in bone marrow of MDS.

Adult↗
PubMed1999

Flagellar proteins and type III-exported virulence factors are the predominant proteins secreted into the culture media of Salmonella typhimurium.

We analysed all major proteins secreted into culture media from Salmonella typhimurium. Proteins in culture supernatants were collected by trichloroacetic acid precipitation, separated in SDS-polyacrylamide gels and analysed by amino acid sequencing. Wild-type strain SJW1103 cells typically gave rise to nine bands in SDS gels: 89, 67, 58, 52, 50, 42, 40, 35 and (sometimes) 28 kDa. A search of the sequences in the available databases revealed that they were either flagellar proteins or virulence factors. Six of them were flagella specific: FlgK or HAP1 (58 kDa), FliC or flagellin (52 kDa), FliD or HAP2 (50 kDa), FlgE or hook protein (42 kDa), FlgL or HAP3 (35 kDa) and FlgD or hook-cap protein (28 kDa). The other four bands were specific for virulence factors: SipA (89 kDa), SipB (67 kDa), SipC (42 kDa) and InvJ (40 kDa). The 42 kDa band was a mixture of FlgE and SipC. We also analysed secreted proteins from more than 30 flagellar mutants, and they were categorized into four groups according to their band patterns: wild type, mot type, polyhook type and master gene type. Virulence factors were constantly secreted at a higher level in all flagellar mutants except a deltamot (motAB deletion) mutant, in which the amounts were greatly reduced. A new morphological pathway of flagellar biogenesis including protein secretion is presented.

Actins↗
PubMed1999

Regulation of gibberellin biosynthesis genes during flower and early fruit development of tomato.

Gibberellins (GAs) are essential for the development of fertile flowers in tomato, and may also be required immediately after fertilization. In the GA-biosynthetic pathway, the reactions catalyzed by GA 20-oxidases have been implicated as site of regulation. To study the regulation of GA biosynthesis in flower and early fruit development, we isolated three tomato GA 20-oxidase cDNA clones, Le20ox-1, -2 and -3. The three genes showed different organ-specific patterns of mRNA accumulation. Analysis of the transcript levels of the three GA 20-oxidase genes, as well as those of copalyl diphosphate synthase (LeCPS) and GA 3 beta-hydroxylase (Le3OH-2) during flower bud and early fruit development, revealed temporally distinct patterns of mRNA accumulation. Up until anthesis, transcripts were observed for LeCPS, Le20ox-1, -2 and Le3OH-2, with an accumulation of Le20ox-1 mRNA. In contrast to the high level of Le3OH-2 transcripts in the fully open flower, mRNA levels of Le20ox-1, -2 and LeCPS were reduced at this stage. After anthesis, LeCPS and Le20ox-1 transcripts increased again. In addition, Le20ox-3transcripts increased whereas the transcripts of Le3OH-2 decreased to an undetectable level. In situ hybridization results demonstrated that during early stages of bud development, Le20ox-2 transcripts were localized in the tapetum and placenta. The presented results supply novel data about localization of GA biosynthesis gene transcripts, and indicate that transcript levels of GA biosynthesis genes are all highly regulated during flower bud development.

Alkyl and Aryl Transferases↗
PubMed1999

A novel egg-derived tyrosine phosphatase, EDTP, that participates in the embryogenesis of Sarcophaga peregrina (flesh fly).

We have previously reported that cathepsin L mRNA is present in unfertilized eggs of Sarcophaga peregrina (flesh fly) as a maternal mRNA, which suggests that cathepsin L is required for embryogenesis. Now we have identified an egg protein, with a molecular mass of 100 kDa, that is extremely susceptible to cathepsin L digestion and which disappears rapidly as the embryos develop. We purified this protein to homogeneity, cloned its cDNA, and found that it contained a consensus sequence for the active site of tyrosine phosphatase. In fact this protein showed tyrosine phosphatase activity, indicating that it is a novel tyrosine phosphatase. The expression and subsequent disappearance of this protein, which we have named egg-derived tyrosine phosphatase (EDTP), may be indispensable for embryogenesis of Sarcophaga.

Amino Acid Sequence↗
PubMed1999

A case of West syndrome well controlled by very short and low-dose ACTH therapy.

The case of a 5-month-old boy with tuberous sclerosis and West syndrome is reported. Tonic spasms were noted from the age of 4 months. High-dose pyridoxal phosphate could not control the seizures completely. Very short and low-dose adrenocorticotropic hormone (ACTH) therapy (i.e. 0.011 mg/kg per dose, 12 times in 20 days) controlled the seizures, while pyridoxal phosphate was on. Early tapering of ACTH was successfully done while abnormal electroencephalogram (EEG) findings remained. Although side effects such as hypertension and brain shrinkage were transiently observed, both the cognitive and seizure prognoses were excellent at the age of 3 years and 2 months. The good response to a small dosage of ACTH might be due to some responsiveness of the high-dose pyridoxal phosphate and the underlying cause of tuberous sclerosis with normal development before onset. The present case illustrates that the duration and dosage of ACTH therapy in West syndrome should be modified according to the individual's requirements.

Adrenocorticotropic Hormone↗
PubMed1999

Proteoglycan core protein in human urine and its possible role on calcium oxalate urolithiasis.

BACKGROUND: There are only a few papers reporting on the role of proteoglycan core protein in calcium oxalate stone formation. The present study was carried out to investigate the role of core protein of proteoglycan in human urine on calcium oxalate (CaOx) crystallization. METHODS: Proteoglycans were collected from whole human urine. The covalently bound glycosaminoglycans (GAG) of proteoglycans were then digested by GAG lyase. The inhibitory activity on CaOx crystal growth in vitro was measured before and after enzyme digestion of proteoglycans. Sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of the core protein of proteoglycans and the analysis of amino acid sequence were performed. RESULTS: The core protein showed significant inhibitory activity on CaOx crystal growth, which scarcely changed when compared with that of proteoglycans before enzyme digestion. The SDS-PAGE revealed that the core protein was a single unit with a molecular weight of 26 kDa and amino acid sequencing demonstrated high homology to interalpha-trypsin inhibitor (ITI) light chain (bikunin) with Kunitz inhibitor domain as a core protein. CONCLUSIONS: The results suggested that human urine contains proteoglycans and a major part of them is ITI light chain (bikunin). The Kunitz inhibitor domain, a core protein of bikunin, has significant inhibitory activity on CaOx crystallization without GAG bound covalently to the core protein.

Adult↗
PubMed1999

The dorsal ligaments of the wrist: anatomy, mechanical properties, and function.

The purpose of this study was to examine the anatomy and mechanical properties of the dorsal radiocarpal (DRC) and dorsal intercarpal (DIC) ligaments of the wrist and to better understand the functional design of the dorsal ligaments. The DRC ligament was consistently found to originate from the dorsal margin of the distal radius and extended ulnar obliquely and distally. Its radial fibers attached to the lunate and lunotriquetral interosseous ligament. The DRC ligament then inserted onto the dorsal tubercle of the triquetrum. The DIC ligament originated from the triquetrum and extended radially and attached onto the lunate, inserted into the dorsal groove of the scaphoid, and then extended to the trapezium. The DRC and DIC ligaments together, in their lateral V configuration, act effectively as a dorsal radioscaphoid ligament that has the ability to vary its length by changing the angle between the 2 arms of the V. The DRC-DIC ligaments' lateral V configuration allows normal carpal kinematics while maintaining its indirect dorsal stabilizing effect on the scaphoid throughout the range of motion of the wrist.

Adult↗
PubMed1999

Responsiveness to thyroid hormone is enhanced in rat hepatocytes cultured as spheroids compared with that in monolayers: altered responsiveness to thyroid hormone possibly involves complex formed on thyroid hormone response elements.

We previously reported that the expression of type I iodothyronine 5'-deiodinase (5'DI) gene was increased by 3,3,',5-triiodothyronine (T3) in isolated rat hepatocytes when cultured as spherical aggregates (spheroids), whereas this effect was greatly attenuated in conventional monolayer cultures. In the current study, we examined whether the enhanced T3 responsiveness in spheroid cultures extends to other T3-responsive genes. As observed for 5'DI, T3 increased spot 14, malic enzyme and fibronectin messenger RNAs (mRNAs) by fourfold to fivefold in spheroid cultures, while the effect in monolayer cultures was blunted. This difference in T3 responsiveness was also observed when T3-responsive reporters consisting of the luciferase gene under the control of triiodothyronine response element (TRE) were introduced into hepatocytes using a replication-defective adenovirus vector. These results suggest that the factors required for T3-dependent transcriptional activation are preserved in spheroid cultures and that they must exert their effect by interacting with TRE. Maximal binding capacity of nuclear T3 receptor was not different between monolayer and spheroid cultures while the expression of retinoid X receptor-alpha (RXR alpha) mRNA was higher in spheroid cultures compared with that in monolayers. The difference in RXR alpha mRNA expression, together with enhanced proteolytic cleavage in monolayers that we demonstrated recently, may account for the difference in T3 responsiveness between the two hepatocyte culture systems.

Animals↗
PubMed1999

Site-directed mutagenesis of a possible type 1 copper ligand of bilirubin oxidase; a Met467Gln mutant shows stellacyanin-like properties.

In our previous paper, we reported a mutant of recombinant Myrothecium verrucaria bilirubin oxidase, in which the Met467 residue was replaced by Gly [Shimizu, A. et al. (1999) Biochemistry 38, 3034-3042]. This mutant displayed a remarkable reduction in enzymatic activity and an evident decrease in the intensity of the absorption band around 600 nm (type 1 charge transfer transition). In this study, we report the preparation of three Met467 mutants (Met467Gln, Met467His, and Met467Arg) and characterize their enzymatic activities, midpoint potentials, and absorption and ESR spectra. Met467His and Met467Arg show no enzymatic activity and a great reduction in the intensity of the absorption band around 600 nm. Furthermore, their ESR spectra show no type 1 copper signal, but only a type 2 copper signal; however, oxidation by ferricyanide caused the type 1 copper signal to appear. On the other hand, Met467Gln as expressed shows both type 1 and type 2 copper signals in its ESR spectrum, the type 1 copper atom parameters being very different from usual blue copper proteins but very similar to those of stellacyanin. The enzymatic activity of the Met467Gln mutant for bilirubin is quite low (0.3%), but the activity for potassium ferrocyanide is similar (130%) to that of the wild type enzyme. These results indicate that Met467 is important for characterizing the features of the type 1 copper of bilirubin oxidase.

Amino Acid Sequence↗
PubMed1999

Stage-specific inhibition of Xenopus embryogenesis by aprotinin, a serine protease inhibitor.

We examined the effects of various protease inhibitors on Xenopus laevis embryogenesis. Aprotinin, a serine protease inhibitor, was found to inhibit embryogenesis markedly, but other protease inhibitors had virtually no effect. The inhibitory effect of aprotinin was specific for embryos at the blastula or gastrula stage. These results suggest that an aprotinin-sensitive protease involved in embryonic development is secreted from the embryos or appears on the surface of embryonic cells at these stages. We found that various serine proteases are in fact secreted from the embryos with their development and that some of them are sensitive to aprotinin.

Amino Acid Sequence↗
PubMed1999

Mapping the genetic determinants of pathogenicity and plaque phenotype in swine vesicular disease virus.

A series of recombinant viruses were constructed using infectious cDNA clones of the virulent J1'73 (large plaque phenotype) and the avirulent H/3'76 (small plaque phenotype) strains of swine vesicular disease virus to identify the genetic determinants of pathogenicity and plaque phenotype. Both traits could be mapped to the region between nucleotides (nt) 2233 and 3368 corresponding to the C terminus of VP3, the whole of VP1, and the N terminus of 2A. In this region, there are eight nucleotide differences leading to amino acid changes between the J1'73 and the H/3'76 strains. Site-directed mutagenesis of individual nucleotides from the virulent to the avirulent genotype and vice versa indicated that A at nt 2832, encoding glycine at VP1-132, and G at nt 3355, encoding arginine at 2APRO-20, correlated with a large-plaque phenotype and virulence in pigs, irrespective of the origin of the remainder of the genome. Of these two sites, 2APRO-20 appeared to be the dominant determinant for the large-plaque phenotype but further studies are required to elucidate their relative importance for virulence in pigs.

Animals↗
PubMed1999

High IL-18 (interferon-gamma inducing factor) concentration in a purine nucleoside phosphorylase deficient patient.

The plasma concentration of IL-18 (interferon-gamma inducing factor) was severely increased in a 3 year old boy with purine nucleoside phosphorylase (PNP) deficiency. The presence and activity of IL-18 were confirmed by immunoblotting and bioassay, respectively. These results suggest that IL-18 may be abundantly produced and secreted into plasma by PNP deficient macrophages in PNP deficiency.

Biomarkers↗
PubMed1999

Effects of zinc acexamate (NAS-501) on superoxide radicals and lipid peroxidation of rat gastric mucosa.

Zinc acexamate (NAS-501), an anti-ulcer agent, has been reported to prevent various acute experimental gastric mucosal lesions and duodenal ulcers in rats. In order to clarify the mechanisms by which NAS-501 exhibits the anti-ulcer effects, we investigated the anti-oxidative effects of NAS-501 in vitro and in vivo. NAS-501 significantly reduced the superoxide radical-dependent chemiluminescence, generated by hypoxanthine-xanthine oxidase, rat neutrophils and guinea-pig macrophages in vitro. These in vitro effects were also confirmed by electron spin resonance using a 5, 5-dimethyl-1-pyrroline-N-oxide spin-trapping method. In addition, NAS-501 significantly inhibited lipid peroxidation induced by increasing concentrations of Fe2+/ascorbate in rat gastric mucosal homogenate in vitro. Oral administration of NAS-501 (30 mg/kg) significantly inhibited production of thiobarbituric acid-reactive substance in rat gastric mucosa following per os instillation of 60% ethanol in 150 mmol/l HCl in vivo. These results suggest that NAS-501 exhibits the preventive effect from acute gastric mucosal lesions by the anti-oxidative activity.

Aminocaproates↗
PubMed1999

Inhibitory effect of chalcone derivatives on recombinant human aldose reductase.

More than fifty chalcone derivatives were synthesized to examine structure-activity relationships against human aldose reductase. Certain 2',4'-dihydroxychalcone derivatives inhibited human aldose reductase activities, and 2',4',2, 4-tetrahydroxychalcone and 2',4',2-trihydroxychalcone showed potent inhibitory activity with IC50 values of 7.4x10(-9) M and 1.6x10(-7) M, respectively. On the other hand, cis-form chalcones, which were isomerized from the original trans-forms by irradiation of daylight in methanol solution, promoted the activity of human aldose reductase.

Aldehyde Reductase↗
PubMed1999

Anti-inflammatory cytokine profile in human heart failure: behavior of interleukin-10 in association with tumor necrosis factor-alpha.

Proinflammatory cytokines, i.e., tumor necrosis factor-alpha (TNFalpha), participate in the development and the progression of congestive heart failure (CHF). On the other hand, an anti-inflammatory cytokine may neutralize the proinflammatory cytokines of CHF. Interleukin-10 (IL-10) is known to suppress the synthesis of proinflammatory cytokines. IL-10 and the IL-10 receptor system was investigated in comparison with the behavior of TNFalpha in 68 patients with various causes of CHF (mean age: 61 years) and in 31 normal subjects (61 years). The circulating IL-10 level was higher in CHF patients than in normal subjects (p<0.05). The TNFalpha level was higher in CHF patients than in control subjects (p<0.005). The ratio of IL-10 to TNFalpha tended to be higher in control subjects than in patients with CHF (p = 0.09). With lipopolysaccharide treatment, the release of IL-10 was more enhanced from mononuclear leukocyte of patients with CHF than from control subjects (p<0.05). The expression of the IL-10 receptor estimated by flow cytometry of mononuclear leukocytes was higher in the CHF patients than in the normal subjects. The IL-10/IL-10 receptor system was activated, at least partly, to downregulate an excess of TNFalpha in patients with advanced CHF. IL-10 may be an important inherent component of the cytokine network of CHF.

Adult↗
PubMed1999

Effects of phenylephrine and prazosin on axial movement of the rat incisor and arterial blood pressure.

We investigated the dose-response effects of phenylephrine and antagonistic effects of prazosin on axial movement of the rat incisor and arterial blood pressure. Phenylephrine caused a temporal extrusive tooth movement and an increase in blood pressure at all doses. With increasing phenylephrine doses, the maximum extrusive tooth movement and maximum increase in blood pressure were enhanced. The maximum extrusive tooth movement and increase in blood pressure induced by phenylephrine were markedly suppressed after pretreatment with prazosin. These results suggested that extrusive tooth movement is closely related to the rise in blood pressure due to stimulation of vascular alpha1-receptors.

Adrenergic alpha-Agonists↗