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Biomedical subjects

M Hayashi

Publications and source records attributed to M Hayashi.

At least 253 records · Page 14Linked to original sources
PubMed2000

AtPex14p maintains peroxisomal functions by determining protein targeting to three kinds of plant peroxisomes.

We previously isolated an Arabidopsis: peroxisome-deficient ped2 mutant by its resistance to 2,4-dichlorophenoxybutyric acid. Here, we describe the isolation of a gene responsible for this deficiency, called the PED2 gene, by positional cloning and confirmed its identity by complementation analysis. The amino acid sequence of the predicted protein product is similar to that of human Pex14p, which is a key component of the peroxisomal protein import machinery. Therefore, we decided to call it AT:Pex14p. Analyses of the ped2 mutant revealed that AT:Pex14p controls intracellular transport of both peroxisome targeting signal (PTS)1- and PTS2-containing proteins into three different types of peroxisomes, namely glyoxysomes, leaf peroxisomes and unspecialized peroxisomes. Mutation in the PED2 gene results in reduction of enzymes in all of these functionally differentiated peroxisomes. The reduction in these enzymes induces pleiotropic defects, such as fatty acid degradation, photorespiration and the morphology of peroxisomes. These data suggest that the AT:Pex14p has a common role in maintaining physiological functions of each of these three kinds of plant peroxisomes by determining peroxisomal protein targeting.

Amino Acid Sequence↗
PubMed2000

Hepatic copper accumulation induces DNA strand breaks in the liver cells of Long-Evans Cinnamon strain rats.

Effects of accumulation of copper and iron on the production of DNA strand breaks were investigated in Long-Evans Cinnamon (LEC) strain rats that spontaneously develop fulminant hepatitis. Copper and iron accumulated in the liver of LEC rats in an age-dependent manner from 4 to 15 weeks. Low-copper food prevented the accumulation of copper in the liver, but did not prevent accumulation of iron. When the amounts of DNA single strand breaks were estimated by comet assay, the number of DNA strand breaks in the liver cells of rats fed standard food increased with age from 4 to 15 weeks. The number of DNA strand breaks in the liver cells from rats fed low-copper food were the same as those of rats at 4 weeks of age. Thus, the copper accumulation in the liver of LEC rats induced DNA strand breaks, but accumulation of iron did not.

Animals↗
PubMed2000

Transcardiac extraction of circulating endothelin-1 across the failing heart.

To determine the transcardiac gradient of plasma endothelin-1 (ET-1) in patients with congestive heart failure (CHF), we measured plasma levels of ET-1 in both the aortic root and the coronary sinus in 14 normal subjects and 79 consecutive patients with CHF. In normal subjects, plasma ET-1 was significantly higher in the coronary sinus than in the aortic root; these findings were also shown in patients with mild CHF, suggesting that there was ET-1 spillover across the heart. In contrast, plasma ET-1 was significantly lower in the coronary sinus than in the aortic root in patients with severe CHF, suggesting there was ET-1 extraction across the heart in patients with severe CHF. The transcardiac gradient of plasma ET-1 was correlated with the left ventricular end-diastolic volume index (r = 0.501, p <0.0001) and plasma level of procollagen type III amino terminal peptide in the coronary sinus (r = 0.54, p = 0.0008), a marker of myocardial fibrosis. Stepwise multivariate analysis showed that the transcardiac gradient of plasma ET-1 was an independent and significant relation with the left ventricular end-diastolic volume index in patients with CHF (r = 0.665, p <0.0001). These findings suggest that elevated circulating ET-1 is extracted across the failing heart with a significant correlation between the transcardiac gradient of plasma ET-1 and the left ventricular end-diastolic volume index, suggesting that ET receptors are upregulated in the failing ventricle and that the elevated circulating ET-1 might stimulate the process of left ventricular remodeling in patients with severe CHF.

Angiotensin II↗
PubMed2000

The lack of compound 48/80-induced contraction in isolated trachea of mast cell-deficient Ws/Ws rats in vitro: the role of connective tissue mast cells.

In the rat trachea, two types of mast cells have been identified, connective tissue mast cells and mucosal mast cells. Their different characteristics may account for their different biological functions. The role of connective tissue mast cells in tracheal contraction as one feature of the immediate reaction of asthma was studied in vitro in isolated trachea, using tissue derived from mast cell-deficient (Ws/Ws) rats, heterozygous (Ws/+) rats and control (+/+) rats, and compound 48/80 as a potent inducer of mast cell degranulation. The contractile response of tracheas from the three types of rats was also studied upon exposure to the following spasmogens: histamine, 5-hydroxytryptamine (5-HT), and carbachol. Histamine content in tissues reflected the differing mast cell numbers in strips from the three rat types. It was found that carbachol and 5-HT elicited tracheal contraction in a similar manner in strips from the three types of rats. Histamine had no contractile effect. Compound 48/80, at a dose of 25 microg/ml, elicited contraction in tracheas from both control (+/+) and heterozygous (Ws/+), but not in trachea from Ws/Ws rats. Compound 48/80-induced contractions in tracheas from +/+ rats were inhibited by 0.1 microM ketanserin and 0.1 microM nedocromil, but not by 0.1 microM mepyramine. Enzyme histochemistry confirmed that the degranulation occurred in connective tissue mast cells, but not in mucosal mast cells. We concluded that connective tissue mast cells play an important role in rat tracheal contraction via 5-HT release induced by compound 48/80. In addition, the specific mast cell-deficient (Ws/Ws) rats provide a good tool for studying the roles of mast cells in airway system.

Animals↗
PubMed2000

Expression of GAP-43 and SCG10 mRNAs in lateral geniculate nucleus of normal and monocularly deprived macaque monkeys.

We performed nonradioactive in situ hybridization histochemistry (ISH) in the lateral geniculate nucleus (LGN) of the macaque monkey to investigate the distribution of mRNA for two growth-associated proteins, GAP-43 and SCG10. GAP-43 and SCG10 mRNAs were coexpressed in most neurons of both magnocellular layers (layers I and II) and parvocellular layers (layers III-VI). Double-labeling using nonradioactive ISH and immunofluorescence revealed that both GAP-43 and SCG10 mRNAs were coexpressed with the alpha-subunit of type II calcium/calmodulin-dependent protein kinase, indicating that both mRNAs are expressed also in koniocellular neurons in the LGN. We also showed that GABA-immunoreactive neurons in the LGN did not contain GAP-43 and SCG10 mRNAs, indicating that neither GAP-43 nor SCG10 mRNAs were expressed in inhibitory interneurons in the LGN. GABA-immunoreactive neurons in the perigeniculate nucleus, however, contained both GAP-43 and SCG10 mRNAs, indicating that both mRNAs were expressed in inhibitory neurons in the perigeniculate nucleus, which project to relay neurons in the LGN. Furthermore, to determine whether the expression of GAP-43 and SCG10 mRNAs is regulated by visual input, we performed nonradioactive ISH in the LGN and the primary visual area of monkeys deprived of monocular visual input by intraocular injections of tetrodotoxin. Both mRNAs were downregulated in the LGN after monocular deprivation for 5 d or longer. From these results, we conclude that both GAP-43 and SCG10 mRNAs are expressed in the excitatory relay neurons of the monkey LGN in an activity-dependent manner.

Animals↗
PubMed2000

Mouse integrin alphav promoter is regulated by transcriptional factors Ets and Sp1 in melanoma cells.

A 17-bp region between the -31 and -15 bp region of the mouse integrin alphav gene is known to be one of the cis-acting elements for promoter activity. Experimental binding of nuclear proteins to the -31/-15 region reveals that the -27/-16 region mediates the binding. The -27/-16 region, GGCTCCTCCTCC, has a TCCTCC motif, one of the Sp1 binding motifs. An anti-Sp1 IgG and an Sp1-binding oligonucleotide interfered with the binding of nuclear proteins to the -27/-16 oligonucleotide, demonstrating that Sp1 binds to the -27/-16 region. In addition to the -27/-16 region, two other regions, -108/-89 and -64/-44, were found to bind to nuclear proteins within the -108/+1 alphav promoter region. An oligonucleotide containing the Ets-binding consensus sequence of CAGGAAGT interfered with their binding, indicating that both regions have a functional Ets-binding site; which is ACGGAAGT from -106 to -99 bp and ACTTCCTC from -61 to -54 bp, as deduced from the sequence. Mutations in or deletions from any one of three cis-acting elements, the two Ets-binding sites or one Sp1-binding site, remarkably decreased the promoter activity detected in the -108/+1 region. Cotransfection of both Sp1 and Ets-1 cDNAs with the -108/+1 region into B16F10 cells increased the promoter activity 2.9-fold. These results demonstrate that Sp1 and Ets cooperate to activate the -108/+1-alphav promoter region.

Animals↗
PubMed2000

Preparation, X-ray crystal structure, and 195Pt NMR spectra of platinum(II) with dipeptides and dipeptide methyl esters.

Three dipeptide complexes of the form K[M(dipeptide)Cl] (H2dipeptide=glycylbeta-alanine, beta-alanylglycine, beta-alanylbeta-alanine) and four dipeptide methyl ester complexes of the form K[M(dipeptideOMe)Cl2] (HdipeptideOMe=glycylalpha-alanine methyl ester, alpha-alanylglycine methyl ester, dialpha-alanine methyl ester) were newly prepared. The K[Pt(glybeta-ala)Cl] complex crystallizes in the monoclinic space group C2/c with unit cell dimensions of a=25.77(1) A, b=4.09(2) A, c= 16.432(9) A, beta=103.74(4) degrees, and Z=8. The K[Pt(glyalpha-alaOMe)Cl2] complex crystallizes in the monoclinic space group P1 with unit cell dimensions of a=7.195(2) A, b=7.977(5) A, c=10.326(3) A, alpha=72.49(3) degrees, beta=103.74(4) degrees, gamma=88.27(4) degrees and Z=2. The 195Pt NMR peaks of the complexes containing the beta-alanine moiety appeared significantly more upfield than those of the complexes containing diglycine. The ratios of the species of the platinum complexes containing the dipeptide ester in neutral solution were significantly different from those in alkaline solution at 40 degrees C for a short time.

Crystallography, X-Ray↗
PubMed2000

Living donor liver transplantation for fulminant hepatic failure.

BACKGROUND: Living donor liver transplantation (LDLT) was originally indicated only for elective cases of pediatric patients with end-stage liver disease. In Japan, however, where liver transplantation from brain-dead donor is performed very rarely, this indication has been expanded to emergency cases such as fulminant hepatic failure (FHF). METHODS: Thirty-eight patients with FHF were treated between May 1992 and April 1999. Causes of acute liver failure were non-A, non-B hepatitis in 27 patients, hepatitis B virus in seven, and hepatitis A virus, Epstein-Barr virus, herpes simplex virus, and chrome poisoning in one each. RESULTS: Four patients did not undergo LDLT because of severe brain damage or combined multiple organ failure. The remaining 34 patients underwent a total of 36 LDLTs, including two retransplantations; 16 children received transplants of 17 lateral segments, three children and eight adults transplants of 11 left lobes, and seven adults transplants of eight right lobes. A total of 15 recipients died, four of primary graft dysfunction, three of refractory acute rejection, two of pneumonia, and one each of ductopenic rejection, sepsis, aplastic anemis, recurrence of Epstein-Barr virus hepatitis, multiple organ failure by chrome poisoning, and unknown hepatic failure. Primary graft dysfunction developed in adult recipients with small-for-size graft transplants, whereas refractory acute rejection and ductopenic rejection occurred in six grafts each of children with non-A, non-B FHF. CONCLUSIONS: LDLT can be safely expanded to cases of FHF in adult patients. Primary graft dysfunction in adult recipients with small-for-size left lobe grafts can be overcome by using right lobes. However, refractory acute rejection and ductopenic rejection in children remain a major problem.

Adolescent↗
PubMed2000

In vivo genotoxicity of 2-amino-3,8-dimethylimidazo[4, 5-f]quinoxaline in lacI transgenic (Big Blue) mice.

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), a heterocyclic amine found in cooked meat, is a strong mutagen in the Salmonella/microsome assay and was proven to be a hepatocarcinogen in rodents. We used the lacI transgenic (Big Blue(R)) mouse to investigate MeIQx genotoxicity in vivo. lacI mutant frequencies were examined in liver and colon after single intragastric administration of MeIQx (males) or 12 weeks of feeding in the diet (males and females). Micronucleus induction was monitored in the peripheral blood and cell proliferating activity was monitored by proliferating cell nuclear antigen (PCNA) immunostaining, but only after the intragastric administration. Intragastric treatment with MeIQx (100 mg/kg) did not increase mutant frequency (MF) in liver or colon but it did induce a slight but statistically significant increase in the incidence of micronucleated reticulocytes 48 h after the treatment. No apparent increase in PCNA-positive foci was observed in any of tissues analyzed 14 days after the treatment. Administration of MeIQx (300 ppm) in diet for 12 weeks, however, caused MF increases in liver and colon in male and female mice, with greater increases in the females. An increase was also obvious after 4 weeks, but only in females. The sex difference in MF is consistent with the fact that female mice are more susceptible to MeIQx carcinogenesis. These results demonstrated that in the transgenic mouse mutation assay, long-term feeding of MeIQx was more effective than single gastric exposures in revealing the compound's mutagenicity in the target organs of carcinogenicity and that sex differences in susceptibility can also be observed.

Administration, Oral↗
PubMed2000

2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces binding of a 50 kDa protein on the 3' untranslated region of urokinase-type plasminogen activator mRNA.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), a highly toxic compound that has recently attracted much attention as an environmental contaminant, elicits a variety of toxic responses. Most, if not all, of the toxic effects of TCDD are thought to result from alteration of gene expression. TCDD acts through both transcriptional and posttranscriptional mechanisms to alter gene expression of many genes. Transforming growth factor (TGF)-alpha and urokinase-type plasminogen activator (uPA) are examples of the genes up-regulated posttranscriptionally by TCDD by mRNA stabilization. While effects of TCDD on transcription have been extensively studied, the molecular mechanisms underlying the TCDD-induced changes in mRNA stability are poorly understood. In this study, we investigated the trans-acting factors involved in TCDD-dependent mRNA stabilization. UV-crosslinking study showed that a liver cytoplasmic protein of 50 kDa (p50) selectively recognized the 3' UTR of the uPA mRNA in a TCDD-dependent manner. We also showed that the activation of p50 by TCDD is mediated through a protein phosphorylation cascade but not via de novo protein synthesis. This is the first study to show the presence of the TCDD-dependent RNA binding activity which may be involved in TCDD-dependent stabilization of mRNA.

3' Untranslated Regions↗
PubMed2000

Covalently bound flavin in the NqrB and NqrC subunits of Na(+)-translocating NADH-quinone reductase from Vibrio alginolyticus.

Na(+)-translocating NADH-quinone reductase (NQR) from the marine bacterium Vibrio alginolyticus is composed of six subunits (NqrA to NqrF). On SDS-PAGE of the purified complex, NqrB and NqrC subunits were found to give yellow-green fluorescent bands under UV illumination. Both the NqrB and NqrC, electroeluted from the gel, had an absorption maximum at 448 nm, and the fluorescence excitation maxima at 365 and 448 nm and the emission maximum at 514 nm. The electroeluted NqrB and NqrC, respectively, were identified from their N-terminal amino acid sequences. These results clearly indicated that the NqrB and NqrC subunits have covalently bound flavins. The two subunits were digested by protease and then the fluorescent peptide fragments were separated by a reversed-phase high performance liquid chromatography. N-Terminal amino acid sequence analyses of the fluorescent peptides revealed that the flavin is linked to Thr-235 in the NqrB and Thr-223 in the NqrC subunits. This is the first example that the flavin is linked to a threonine residue. The amino acid sequence around the flavin-linked threonine was well conserved between NqrB and NqrC. Identification of the flavin group is in progress.

Amino Acid Sequence↗
PubMed2000

Electronic interactions in a new fullerene dimer: C(122)H(4), with two methylene bridges

The isolation of a new fullerene dimer, C(122)H(4), and its structural characterization by (13)C NMR and (1)H NMR spectroscopy and by UV/vis and IR spectroscopy are reported. The structure of this dimer consists of two fullerene cages, which are directly connected through two C-C bonds and two methylene bridges. Consequently, adjacent hexagonal faces of the two fullerene cages are arranged in a face to face manner. Molecular orbital calculations indicate that the proximity of the fullerene cages results in significant through space overlap in both the HOMO and LUMO. As a consequence of this overlap, the electrochemistry of the dimer shows electronic communication with stepwise reduction of each cage.

Journal Article↗
PubMed2000

Hormonal regulation of early follicle development in the rat ovary.

Although earlier studies focused on the hormonal regulation of antral and preovulatory follicles, recent studies indicate the importance of the hormonal control mechanism for preantral follicles. The endocrine hormone FSH is not only a survival factor for early antral follicles but also a potent growth and differentiation factor for preantral follicles. In addition, KGF secreted by theca cells and c-kit ligand secreted by granulosa cells play paracrine roles in the regulation of preantral follicle growth and development. Furthermore oocyte-derived GDF-9 promotes the growth and differentiation of early follicles by acting on somatic cells in the follicle. It is likely that the genetic makeup of an oocyte could determine the secretion of oocyte hormones which would, in turn, regulate the growth and differentiation of the surrounding somatic cells of that follicle. A better understanding of the hormonal mechanisms underlying early follicle development could provide a refined culture system for the in vitro maturation of fertilizable oocytes and future design of fertility and contraceptive agents.

Animals↗
PubMed2000

Os odontoideum with cerebellar infarction: a case report.

STUDY DESIGN: A case report. OBJECTIVES: To report the case of a child with os odontoideum associated with cerebellar infarction and to discuss the correlation between atlantoaxial instability with os odontoideum and vertebrobasilar artery insufficiency. SUMMARY OF BACKGROUND DATA: Knowledge of the influence of atlantoaxial instability on vertebrobasilar artery insufficiency remains limited despite the publication of several reports. METHODS: A 5-year-old boy with ataxic gait disturbance was hospitalized in the pediatric ward. Magnetic resonance imaging revealed multiple cerebellar infarctions, and cerebral angiogram showed occlusions of several branches of the basilar artery and a winding of the left vertebral artery. Stress lateral radiographs of the cervical spine showed atlantoaxial instability with os odontoideum. Posterior C1-C2 transarticular screw fixation with iliac bone graft was applied to obtain firm stability and fusion. RESULTS: There was no damage to the vertebral arteries or spinal nerves in the perioperative period. Solid union of the grafted bone and rigid stability of the atlantoaxial joint were seen on lateral flexion-extension radiographs 1 year after the operation. There has been no sign of recurrent arterial insufficiency, and the patient has been free from cerebellar dysfunction to date. CONCLUSIONS: Atlantoaxial instability may cause insufficiency of the vertebral artery as well as spinal cord injury. More attention should be paid to the possible relation between atlantoaxial instability and vertebrobasilar artery insufficiency.

Atlanto-Axial Joint↗
PubMed2000

Characterization and identification of (CT)n microsatellites in soybean using sheared genomic libraries.

Three small insert (300 to approximately 600 bp) sheared genomic libraries were constructed by pipetting and DNase I treatment of soybean DNA. About 15,000 clones from each library were screened for CT- simple sequence repeats (CT-SSRs). The CT-SSRs were abundant in the soybean genome at an estimated frequency of approximately one SSR per 110 kb of genomic DNA. Following the sequencing of 129 positive clones, the repeat types and frequency of CT repeats among the positive clones were characterized. Forty-nine primer pairs were designed and preliminarily evaluated for their ability to amplify genomic DNA from a set of six varieties, including parents of a mapping family. Amplified products were analyzed by 10% PAGE. Eighty-eight percent of the designed primers were able to amplify all these genomic DNAs using a single PCR profile of 53 degrees C annealing temperature, of which 22 (45%) were polymorphic in the six varieties, and 14 of them were polymorphic in the parents of the mapping family. The polymorphic primer sets were further assessed for allelic information using DNA from 16 soybean cultivars. The average number of alleles was 4, ranging from 2 to 7 with the highest polymorphism information content value 0.84. Fourteen of these SSRs were mapped, using an existing soybean RFLP map. The findings presented here will advance our understanding of the soybean genome, and assist in the mapping genome and discrimination of closely related varieties of this species.

Chromosome Mapping↗
PubMed2000

Absence of TrkB and insulin receptor beta in the Triton insoluble low-density fraction (raft).

Cholesterol- and glycolipid-enriched microdomains within the plasma membrane of animal cells, including neurons, have been purified and used as a low-density membrane domain after extraction with Triton X-100 (raft), or after subcellular fractionation without detergent (LDM). In this study, we compared the protein compositions in the raft and the LDM. Membrane receptors, acylated- and glycosylphosphatidylinositol (GPI)- anchored proteins were enriched in the LDM. Further treatment of the LDM with Triton X-100 excluded the membrane receptors, TrkBs and insulin receptor beta. In the presence of calcium ions, the endogenous tyrosine kinase activities in the LDM and the raft were enhanced, suggesting an important role of calcium ions in the signal transduction via the LDM and the raft.

Acetylation↗
PubMed2000

Rapid immunologic diagnosis of classic late infantile neuronal ceroid lipofuscinosis.

OBJECTIVE: To establish a new method for rapid diagnosis of late infantile neuronal ceroid lipofuscinosis (LINCL, CLN2) using specific polyclonal antibodies against the CLN2 gene product. METHODS: Cells and tissues were obtained from five patients with LINCL, two with variant type NCL, three with other lysosomal storage diseases, and eight control subjects. Two antibodies were raised against N- and C-terminal peptide fragments of the normal product of the CLN2 gene. The authors examined the possibility of diagnosis of LINCL with immunostaining and immunoblotting using specific antibodies made of the recently identified defective gene in LINCL. RESULTS: Immunoreactivity with these antibodies showed the absence or marked reduction of CLN2 immunoreactivity in the lymphocytes, lymphoblasts, and fibroblasts of all five patients with LINCL examined. CONCLUSIONS: These results indicate the usefulness of this diagnostic method based on the changes in CLN2 immunoreactivity. This relatively simple, specific, and cost-effective method is a promising diagnostic tool for this disease, although additional studies are necessary.

Aminopeptidases↗