Biomedical subjects

A Yamaguchi

Publications and source records attributed to A Yamaguchi.

At least 19 recordsLinked to original sources

PubMed2006

Minority spin condensate in the spin-polarized superfluid 3He A1 phase.

The magnetic properties of (3)He in its various phases originate from the interactions among the nuclear spins. The spin-polarized 'ferromagnetic' superfluid (3)He A(1) phase (which forms below 3 mK between two transition temperatures, T(c1) and T(c2), in an external magnetic field) serves as a material in which theories of fundamental magnetic processes and macroscopic quantum spin phenomena may be tested. Conventionally, the superfluid component of the A(1) phase is understood to contain only the majority spin condensate, having energetically favoured paired spins directed along the external field and no minority spin condensate having paired spins in the opposite direction. Because of difficulties in satisfying both the ultralow temperature and high magnetic field required to produce a substantial phase space, there exist few studies of spin dynamics phenomena that could be used to test the conventional view of the A(1) phase. Here we develop a mechanical spin density detector that operates in the required regime, enabling us to perform measurements of spin relaxation in the A(1) phase as a function of temperature, pressure and magnetic field. Our mechanical spin detector is based in principle on the magnetic fountain effect; spin-polarized superfluid motion can be induced both magnetically and mechanically, and we demonstrate the feasibility of increasing spin polarization by a mechanical spin filtering process. In the high temperature range of the A(1) phase near T(c1), the measured spin relaxation time is long, as expected. Unexpectedly, the spin relaxation rate increases rapidly as the temperature is decreased towards T(c2). Our measurements, together with Leggett-Takagi theory, demonstrate that a minute presence of minority spin pairs is responsible for this unexpected spin relaxation behaviour. Thus, the long-held conventional view that the A(1) phase contains only the majority spin condensate is inadequate.

Journal Article↗

PubMed2006

Photon emissions from rice cells elicited by N-acetylchitooligosaccharide are generated through phospholipid signaling in close association with the production of reactive oxygen species.

Biophotons are ultraweak light emissions from biochemical reactions in a living body. They increase in suspension-cultured rice (Oryza sativa L.) cells when elicited by N-acetylchitooligosaccharide. Biochemical analyses were undertaken to investigate the relationship between disease response and biophotons in order to clarify the emission mechanism of biophotons caused by this elicitor. Photon emissions induced by N-acetylchitohexaose were suppressed when cells were pretreated with the reactive oxygen species (ROS)-generating inhibitors: pyrocatechol-3,5-disulfonic acid disodium salt (Tiron); diphenylene iodonium (DPI); and salicylhydroxamic acid (SHAM). Conversely, exogenously applied ROS (superoxide and hydrogen peroxide) were able to induce photon emissions. The effects of protein phosphorylation (K-252a) and the Ca(2+) signaling inhibitors, ethylene glycol-bis(beta-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) and LaCl(3), caused photon emissions to decrease. It is clear that photon emissions from rice cells elicited by N-acetylchitohexaose are closely associated with the ROS-generating system, and are regulated by Ca(2+) signaling and protein phosphorylation. Exogenously applied phosphatidic acid (PA), the second messenger in the signal transduction of disease response, raised photon emissions in rice cells. Comparisons of photon emissions from PA and N-acetylchitohexaose regarding time courses, spectral compositions, and the inhibition ratios of several inhibitors, as well as a loss- and gain-of-function assay using the protein synthesis inhibitor cycloheximide (CHX) and PA, showed the possibility that photon emissions from rice cells elicited by N-acetylchitooligosaccharide were generated through PA, an intermediate of phospholipid signaling.

Oligosaccharides↗

PubMed2006

CSF1 gene associated with aggressive periodontitis in the Japanese population.

Aggressive periodontitis (AgP) is characterized by the early onset of the rapid and progressive destruction of the alveolar bone. We investigated the correlation of single nucleotide polymorphisms (SNPs) in candidate genes with AgP in the Japanese population in order to determine the genetic risk factors for this complex disease. Among 11 genes related to bone formation and resorption, 43 known SNPs were tested in 98 case and 88 control samples for association with AgP by using SNP genotyping techniques. Among these, three polymorphisms located in the colony stimulating factor 1 (CSF1) gene showed a positive association with AgP. This is the first case of an association between a CSF1 polymorphism and a human disease.

Adolescent↗

PubMed2006

Evaluation of RANK/RANKL/OPG gene polymorphisms in aggressive periodontitis.

BACKGROUND AND OBJECTIVE: Aggressive periodontitis (AgP) is a specific type of periodontal disease that is characterized by rapid attachment loss and bone destruction. While attempting to identify genetic polymorphisms associated with AgP, previous research has focused on candidate genes that may be involved in immune responses to microbial infections. In this study, the focus was on single nucleotide polymorphisms (SNPs) in the key mediators of osteoclast differentiation and activation, which involve receptor activator of nuclear factor-kappaB (RANK), RANK ligand (RANKL) and osteoprotegrin (OPG), in the Japanese population. The aim of this study was to evaluate the association of RANK/RANKL/OPG gene polymorphisms with AgP in the Japanese population. MATERIAL AND METHODS: We examined 99 patients with AgP and 89 controls from the Japanese population to explore the possibility of RANK/RANKL/OPG loci as candidate regions associated with the disease. All exons and relevant exon-intron boundaries of these three candidate genes were amplified by polymerase chain reaction (PCR) using 19 primers, followed by direct sequencing. The polymorphisms were identified by comparing the sequences obtained from 48 subjects. RESULTS: We identified 27 SNPs in RANK, including 10 novel SNPs and seven SNPs each in both RANKL and OPG. A pairwise linkage disequilibrium analysis using the r2 statistic showed that some SNP pairs from the three loci are in tight linkage disequilibrium. CONCLUSION: An association analysis with allelotypes showed that SNPs identified in the RANK/RANKL/OPG genes have no significant association with AgP in the Japanese population.

Acute Disease↗

PubMed2006

The expression of IGF-I and myostatin mRNAs in skeletal muscle of hypophysectomized and underfed rats during postnatal growth.

AIM: To determine the roles of myostatin and insulin-like growth factor-I (IGF-I) during postnatal growth, we examined IGF-I and myostatin mRNA expression in the skeletal muscles of hypophysectomized and underfed rats during postnatal growth. METHODS: Five-week-old rats were divided into four groups: freely fed control, moderately underfed, severely underfed and hypophysectomized. Four weeks later, blood and muscle samples were gathered to determine serum IGF-I, myosin heavy chain (MHC) isoforms, IGF-I Ea, IGF-I Eb and myostatin mRNA. RESULTS: The weights of soleus, plantaris and masseter muscles were decreased in underfed and hypophysectomized rats. Hypophysectomy resulted in significant increases of type I MHC at the expense of type IIx in plantaris muscle and of neonatal MHC at the expense of types IIx and IIb in masseter muscle. Serum IGF-I was decreased by underfeeding and hypophysectomy. Plantaris muscle IGF-I Ea mRNA in underfed and hypophysectomized rats was significantly lower than in normal controls. Plantaris muscle IGF-I Eb mRNA in underfed rats was significantly lower than in normal controls. Masseter muscle IGF-I Eb mRNA in severely underfed rats was significantly lower than in normal control and hypophysectomized rats. Soleus muscle myostatin mRNA in hypophysectomized rats was significantly higher than in normal and significantly underfed rats. No significant differences in plantaris and masseter muscle myostatin mRNA were observed between groups. CONCLUSION: Suppressed muscle growth caused by hypophysectomy and underfeeding may be attributed mainly to reduced circulating IGF-I and partially to reduced IGF-I mRNA, rather than to a change in myostatin.

Animals↗

PubMed2006

Signaling mechanisms of axon growth inhibition.

Generally, the axons in the adult mammalian central nervous system (CNS) do not regenerate after injuries. This lack of regeneration results in partial disability or complete paralysis. To date, several axon growth inhibitors that are known to inhibit axon regeneration in the CNS have been identified in the myelin. Recent research has revealed the molecular mechanisms underlying the action of these inhibitors. RhoA and Rho-kinase--a downstream effector of RhoA--are key signals that elicit axon inhibition. These findings provide a number of promising strategies to promote axon regeneration after CNS injuries. Some strategies such as Rho/Rho-kinase inhibition have proved effective in animal models. Elucidation of the complete mechanism of the signal transduction will be useful for the development of efficient therapeutic strategies against injuries of the CNS.

Animals↗

PubMed2006

[Effects of intra-coronary and intra-graft administration of nicorandil for coronary spasm after coronary artery bypass grafting].

Coronary artery spasm after coronary artery bypass grafting (CABG) is relatively rare, but when it occurs, it is fatal. In cases of circulatory collapse just after surgery, coronary spasm should be suspected, and immediate diagnosis by coronary angiography is necessary. We conducted a study to assess the clinical characteristics of coronary spasm after CABG and the usefulness of intra-coronary and intra-graft administration of nicorandil. Study subjects were 7 patients (6 men and 1 woman, mean age 60.4 years) in whom coronary spasm after CABG was diagnosed angiographically from January 1992 to December 2003. Off-pump CABG (OPCAB) had been performed in 2 patients. Despite continuous administration of nitroglycerin and diltiazem hydrochloride during surgery, sudden circulatory collapse occurred during surgery or within 24 hours after CABG in all 7 patients. All required mechanical circulatory support, and emergency coronary angiography revealed severe graft and native coronary spasms. Intracoronary and/or intra-graft administration of diltiazem hydrochloride or nitroglycerin was not very effective, however, administration of nicorandil was effective for vasodilatation. One patient suffered brain damage and died, but the other 6 patients recovered and were discharged without complication. In conclusion, intra-coronary and/or intra-graft administration of nicorandil appears to be useful for the treatment of coronary spasm after CABG.

Aged↗

PubMed2006

[Use of a balloon occlusion catheter for descending aortic aneurysm after total arch replacement using the elephant trunk technique].

A 74-year-old man who had previously undergone prosthetic graft replacement of the total aortic arch using the elephant trunk technique and of the abdominal aorta was admitted to our hospital for surgical treatment of descending aortic aneurysm. Computed tomography (CT) on admission revealed descending aortic aneurysm of 6.5 cm in diameter, and the previously placed prosthetic graft was detected in the aneurysm. Surgery for the descending aorta was performed under femoro-femoral partial bypass. During the operation, a balloon occlusion catheter introduced through the right brachial artery into the 'elephant trunk' graft was inflated before the aneurysm was opened, then the previously placed prosthetic graft was cross-clamped and the descending aorta was replaced with a new prosthetic graft with usual fashion. The postoperative course was uneventful.

Aged↗

PubMed2005

Single-molecule magnets: structure and properties of [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 with spin S = 13.

The reaction of 2-(hydroxyethyl)pyridine (hepH) with a 2:1 molar mixture of [Mn3O(O2CMe)6(py)3]ClO4 and [Mn3O(O2CMe)6(py)3] in MeCN afforded the new mixed-valent (16Mn(III), 2Mn(II)), octadecanuclear complex [Mn18O14(O2CMe)18(hep)4(hepH)2(H2O)2](ClO4)2 (1) in 20% yield. Complex 1 crystallizes in the triclinic space group P. Direct current magnetic susceptibility studies in a 1.0 T field in the 5.0-300 K range, and variable-temperature variable-field dc magnetization studies in the 2.0-4.0 K and 2.0-5.0 T ranges were obtained on polycrystalline samples. Fitting of magnetization data established that complex 1 possesses a ground-state spin of S = 13 and D = -0.18 K. This was confirmed by the value of the in-phase ac magnetic susceptibility signal. Below 3 K, the complex exhibits a frequency-dependent drop in the in-phase signal, and a concomitant increase in the out-of-phase signal, consistent with slow magnetization relaxation on the ac time scale. This suggests the complex is a single-molecule magnet (SMM), and this was confirmed by hysteresis loops below 1 K in magnetization versus dc field sweeps on a single crystal. Alternating current and direct current magnetization data were combined to yield an Arrhenius plot from which was obtained the effective barrier (U(eff)) for magnetization reversal of 21.3 K. Below 0.2 K, the relaxation becomes temperature-independent, consistent with relaxation only by quantum tunneling of the magnetization (QTM) through the anisotropy barrier via the lowest-energy MS = +/-13 levels of the S = 13 spin manifold. Complex 1 is thus the SMM with the largest ground-state spin to display QTM.

Journal Article↗

PubMed2005

Possible role of autoantibodies against nephrin in an experimental model of chronic graft-versus-host disease.

Nephrin, a product of the NPHS1 gene, is a component of the slit diaphragms that are found between glomerular foot processes and is a crucial element for glomerular filtration barrier. Recently, nephrin has been focused in a number of studies of proteinuria development including various types of acquired glomerular diseases including minimal change nephrotic syndrome and membranous nephropathy. However, the precise role of nephrin in such acquired glomerular diseases is still unknown. To analyse the role of nephrin further, two kinds of anti-nephrin antibodies were raised in the rabbits and applied to an experimental mouse model of chronic graft-versus-host disease, in which (C57BL/10 x DBA/2) F1 mice developed clinically apparent severe proteinuria with significant glomerular lesions 7 weeks after parental DBA/2 cell transfer. Antibody-sandwich ELISA detected anti-nephrin antibodies during week 2 to week 6, with the peak at week 2 or week 4. Colocalization of nephrin and IgG on week 4, week 6, and week 8 was revealed by confocal microscopic analysis, suggesting that in situ immune complex formation with nephrin in glomerular lesion. Taken together, it seems to be suggested nephrin and its autoantibody have a certain role in the development of glomerular lesion in our model mice.

Animals↗

PubMed2004

Real-space observation of current-driven domain wall motion in submicron magnetic wires.

We report direct observation of current-driven magnetic domain wall (DW) displacement by using a well-defined single DW in a microfabricated magnetic wire with submicron width. Magnetic force microscopy visualizes that a single DW introduced in a wire is displaced back and forth by positive and negative pulsed current, respectively. The direct observation gives quantitative information on the DW displacement as a function of the intensity and the duration of the pulsed current. The result is discussed in terms of the spin-transfer mechanism.

Journal Article↗

PubMed2004

Establishment of a clonal human mesenchymal cell line that retains multilineage differentiation capacity from a spinal hamartoma.

We isolated a single-cell-derived cell line from a spinal hamartoma, a which occurred in a newborn boy and was associated with a rudimentary limb. The maternal cells (HHC-7) differentiated into osteoblasts, chondrocytes, adipocytes, and skeletal muscles when they were cultured in differentiation-inducing media specific to each mesenchymal cell. We isolated a single-cell-derived clonal cell line (Clone K) after transfection with SV40 T antigen. These cells expressed CD73 and CD117, while being negative for expression of CD45. Clone K cells cultured in an osteogenic differentiation medium increased ALP activity and expressed mRNAs for Runx2 and osteocalcin. Treatment with rhBMP-2 induced Clone K cells to differentiate into both osteoblasts and chondrocytes. These cells expressed mRNAs for Sox9 and aggrecan in addition to osteogenic markers. Culture in an adipogenic differentiation medium induced Clone K cells to differentiation into adipocytes, which expressed mRNAs for PPARgamma2 and a2P. Clone K cells cultured in a serum-depleted medium generated desmin-positive cells and expressed MyoD1 mRNA. Clone K cells exhibited numerous alpha-smooth muscle actin-positive cells; however, treatment with rhBMP-2 decreased their number. Clone K cells, transplanted with a carrier containing rhBMP-2 into the muscles of SCID mice, generated ectopic endochondral bone formation. In these tissues, several osteoblasts and chondrocytes expressed SV40 T antigen, indicating their Clone K cell origin. Thus, Clone K cells are useful tools for analyzing the characteristics of human multipotential mesenchymal progenitors.

Adipocytes↗

PubMed2004

Isolation and characterization of a mesenchymal cell line that differentiates into osteoblasts in response to BMP-2 from calvariae of GFP transgenic mice.

We established the clonal mesenchymal cell line, GFP-C3 (C3), which differentiates into osteoblasts in response to BMP-2 from calvariae of newborn green fluorescence protein (GFP) transgenic mice. This cell line cultured with control medium expressed low levels of alkaline phosphatase (ALP) activity and osterix mRNA and undetectable ALP and osteocalcin mRNA. Incubation of these cells with rhBMP-2 increased ALP activity dose-dependently and induced substantial levels of ALP, osteocalcin and osterix mRNA expression. C3 cells infected with adenovirus vector encoding BMP-2 (AdBMP-2) or Runx2 (AdRunx2) showed greatly increased ALP mRNA expression in a time-dependent fashion. Transduction with AdRunx2-induced expression of ALP and osteocalcin mRNA, but not osterix mRNA by day 3. Transduction with AdBMP-2 induced apparent expression of ALP and osterix mRNA by day 1 after transduction, but induced only weak expression of osteocalcin mRNA day 3 after transduction. Transplantation of C3 cells transduced with AdBMP-2 into back subfascia in wild-type mice with a complex of poly-d,l-lactic-co-glycolic acid/gelatin sponge (PGS) generated ectopic bone formation involving GFP-positive osteoblasts and osteocytes 2 weeks after transplantation. C3 cells transduced with AdRunx2 or AdLacZ failed to induce ectopic bone formation. Transplantation of C3 cells transduced with AdBMP-2 into craniotomy defects in wild-type mice using PGS as a carrier induced bone formation 2 weeks after transplantation, and replaced defects 4 weeks after transplantation. C3 cells transduced with AdRunx2 failed to induce bone repair after transplantation into craniotomy defects. These results indicate that C3 cells retain differentiation potential into osteoblasts in response to BMP-2. They are useful tools for analyzing the process of osteoblast differentiation in vivo after transplantation.

Animals↗

PubMed2004

A nonsense mutation (R220X) in the alpha-galactosidase A gene causes typical Fabry disease in both genders.

BACKGROUND: Fabry disease is an X-linked recessive disorder resulting from a deficiency of lysosomal alpha-galactosidase A (alpha-Gal A). Chronic renal failure is an important cause of death in patients with Fabry disease. We report on patients with Fabry disease (a hemizygous male and his mother) due to a nonsense mutation (R220X) in the alpha-Gal A gene. METHODS: The proband, a 41-year-old man, and his 71-year-old mother presented with renal and cardiac manifestations of Fabry disease. Histological examination and molecular analysis of the alpha-Gal A gene were performed. RESULTS: Typical histological findings of Fabry disease were observed in a renal biopsy specimen from the proband and in renal and myocardial necropsy specimens from the mother. Sequencing of a full-length alpha-Gal A cDNA from the proband indicated a C-T transition at codon 220, resulting in substitution of the predictable termination for arginine (R220X). Examination of genomic alpha-Gal A DNA revealed that the proband was a hemizygote and the mother was a heterozygous carrier for the mutation. CONCLUSION: This is the first detailed report of family members with Fabry disease due to a nonsense mutation (R220X) in the alpha-Gal A gene. Our study indicates that this mutation causes the typical disease in both genders.

Adult↗

PubMed2004

[Repair of thoracic and thoracoabdominal aortic aneurisms by the use of hypothermic circulatory arrest].

From 1993 to 2003, repair of thoracic and thoracoabdominal aortic aneurysms using hypothermic circulatory arrest via the left thoracotomy was performed in 115 patients at our hospital. Ninety-one of them were elective cases and 24 of them were emergent cases. Hospital mortality rate was 3.3% in elective cases and 12.5% in emergent cases. Over all hospital mortality rate was 5.2%. Ischemic spinal cord injury was occurred in 2 patients (1.7%). Both of them needed total replacement of thoracoabodominal aorta by the graft. In the near future, Adamkiewicz artery may be detected by the imaging technology preoperatively and we expect the repair of thoracoabdominal aortic aneurysm may become safer operation avoiding spinal cord injury. Hypothermic circulatory arrest is a relatively safe and reliable method for the repair of thoracic and thoracoabdominal aortic aneurysms.

Adult↗

PubMed2004

[Acute pulmonary embolism after cesarean section; report of a case].

We present a case of acute pulmonary embolism (APE) after cesarean section. A cesarean section was performed on a 27-year old woman with normal course. However, one day after operation, she suddenly developed syncope and dyspnea. Soon after the symptom, she developed hypotension 60 mmHg. As a result of various examinations, her illness was diagnosed as APE with right ventricular dysfunction after cesarean section. She was consulted to our hospital for treatment. Soon after her arrival, we treated her for both APE and cardiogenic shock. The combined with antithrombotic therapy using heparin sodium, was successfully treated the patient from cardiogenic shock due to APE with right ventricular dysfunction after cesarean section.

Acute Disease↗

PubMed2003

Transplantation of skin fibroblasts expressing BMP-2 promotes bone repair more effectively than those expressing Runx2.

We investigated the osteogenic potential of skin fibroblasts that overexpressed BMP-2 or Runx2 by using adenoviral vectors. In in vitro experiments, skin fibroblasts infected with adenovirus vector encoding BMP-2 (AdBMP-2) released substantial levels of BMP-2 proteins into culture media, and those infected with adenovirus vector encoding Runx2 (AdRunx2) produced its protein. Transduction of BMP-2 or Runx2, respectively, increased alkaline phosphatase (ALP) activity and induced expression of mRNAs of ALP, osteocalcin, and osterix in skin fibroblasts. In in vivo experiments, we investigated the bone induction activity by transplantation of a complex composed of carrier [poly-D,L-lactic-co-glycolic acid/gelatin sponge (PGS)] and skin fibroblasts (PGS/SF complex). Transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdBMP-2-induced ectopic bone formation when transplanted into the subfascia of back muscle, unlike those infected with AdRunx2. Transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdBMP-2 into craniotomy defects induced bone formation from 2 weeks after transplantation, and almost all PGS was replaced by newly synthesized bone at 6 weeks. To investigate the fate of the transplanted cells, we transplanted skin fibroblasts isolated from green fluorescence protein transgenic mice into craniotomy defects. Transplantation of these skin fibroblasts transfected with AdBMP-2 generated green fluorescence protein-positive osteoblasts and osteocytes, indicating that the transplanted skin fibroblasts differentiated into osteoblastic lineage cells during bone repair. In contrast, transplantation of PGS/SF complexes composed of skin fibroblasts transduced with AdRunx2 induced a few ALP-positive cells at 1 week after transplantation, but their number decreased depending on time after transplantation. In addition, transplantation of these complexes was insufficient to induce bone repair. Taken together, our results suggest that skin fibroblasts expressing BMP-2 are more suitable for cell-mediated therapy of bone repair than those expressing Runx2.

Adenoviridae↗

PubMed2003

Isolation, characterization and expression of 11beta-hydroxysteroid dehydrogenase type 2 cDNAs from the testes of Japanese eel (Anguilla japonica) and Nile tilapia (Oreochromis niloticus).

The Japanese eel (Anguilla japonica) and Nile tilapia (Oreochromis niloticus) 11beta-hydroxysteroid dehydrogenase type 2 (11beta-HSD2) cDNAs were isolated from their respective testes cDNA libraries. The cDNAs predict two peptides of 436 and 406 amino acid residues that share about 42% homology with mammalian 11beta-HSD type 2 proteins. Analysis of the tissue distribution pattern by RT-PCR reveals that 11beta-HSD2 is expressed in a wide variety of tissues in tilapia, with higher expression in kidney and gill of both sexes, and with the highest expression in testis. 11beta-Dehydrogenase activity of the eel 11beta-HSD2 was confirmed by demonstrating the conversion of cortisol to cortisone by the recombinant protein after transient expression of this cDNA clone in COS-1 cells. Bands of approximately 2.7 and approximately 3.8 Kb were detected in Northern blot of eel and tilapia testes respectively, which is consistent with the cloned cDNA sizes of the two species. Northern blot analysis also revealed that the expression of the eel testis 11beta-HSD2 gene could be induced by human chorionic gonadotropin (hCG) injection, implying a role of 11beta-HSD2 in hCG-induced 11-ketotestosterone production and spermatogenesis in the Japanese eel.

11-beta-Hydroxysteroid Dehydrogenases↗