Biomedical subjects

Y Nakajima

Publications and source records attributed to Y Nakajima.

At least 55 records · Page 3Linked to original sources

PubMed2002

Gap function with point nodes in borocarbide superconductor YNi2B2C.

To determine the superconducting gap function of YNi2B2C, the c-axis thermal conductivity kappa(zz) was measured in H rotated in various directions. The angular variation of kappa(zz) in H rotated within the ab plane shows a peculiar fourfold oscillation with narrow cusps. The amplitude of this fourfold oscillation becomes very small when H is rotated conically around the c axis with a tilt angle of 45 degrees. These results provide the first compelling evidence that the gap function has point nodes located along the a and b axes. This unprecedented gap structure challenges the current view on the pairing mechanism.

Journal Article↗

PubMed2002

Application of synchrotron X-ray imaging to phase objects in orthopedics.

Novel imaging of the fine structures of the ribs of a pig and a specimen of human osteosarcoma utilizing the spatial coherence of X-rays was successfully performed with an incident X-ray energy of 30 keV at SPring-8, Japan. The image contrast appearing at the periphery of trabecular bone, small calcifications and small fractures is caused by the phase shift of the X-rays at the boundary of these objects that have different X-ray refractive indices. The image is recorded on mammography film without an intensifying screen. Comparison of the image contrast using different sample-to-film distances, Z, such as Z = 5 m and Z approximately 0 m, showed that the former images were always more informative, i.e. better in resolution and/or image contrast when imaging trabecular bone, bone marrow and small fractures in compact bone, and for imaging cartilage. Radiography using synchrotron X-rays for phase objects should be a powerful tool for diagnosis in orthopedics, especially for bone disease.

Animals↗

PubMed2002

Expression of proinflammatory cytokine mRNA in the lymphatic organs of adult and neonatal pigs.

Inflammatory cytokine mRNA expression in the lymphatic organs of neonatal, 1-month-old and adult pigs was compared. The mRNA expression of interleukin (IL)-1beta, IL-6, IL-18 and tumor necrosis factor (TNF)-alpha in the spleen, thymus, tonsil and popliteal and mesenteric lymph nodes was investigated by semi-quantitative RT-PCR. Stronger IL-1beta mRNA expression was observed in the 1-day-old and 1-month-old piglets than in the adult pigs. In thymus, tonsil and mesenteric lymph node, IL-1beta mRNA expression in 1-day-old piglets was stronger than in 1-month-old pigs. The expression of IL-6 mRNA in the 1-day-old and 1-month-old tonsil tended to be stronger than in the adult pigs. IL-18 and TNF-alpha mRNA expression was constant in all the samples examined. The expression of IL-1beta and IL-6 mRNA may reflect an inflammatory reaction against the exo- and endogenous foreign bodies occurring in the lymphatic organs, especially in the tonsil, of neonatal piglets.

Aging↗

PubMed2002

Regulation of haptoglobin secretion by recombinant bovine cytokines in primary cultured bovine hepatocytes.

We examined the regulation of haptoglobin (Hp) secretion in primary cultured bovine hepatocytes using recombinant bovine (rb) proinflammatory cytokines. The concentrations of Hp in the supernatant of cultured hepatocytes after incubation with rb interleukin (IL)-6, rb tumor necrosis factor (TNF)-alpha, rbIL-1 beta or rbIFN-gamma alone or with combinations of two of these cytokines were measured by ELISA. The rbIL-6, rbTNF-alpha and rbIL-1 beta increased Hp synthesis, but rbIFN-gamma did not, and rbIL-6 was the most effective Hp inducer among these cytokines. The Hp secretion was accelerated synergistically by combined treatment with rbIL-6 and rbTNF-alpha, whereas it remained unchanged with a combination of rbIL-6 and rbIL-1 beta. In contrast, the combination of rbIL-6 and rbIFN-gamma downregulated Hp secretion. In conclusion, IL-6 is the principal cytokine in Hp secretion in bovine hepatocytes in vitro, and its activity may be regulated by other cytokines.

Albumins↗

PubMed2002

Properties of human skin mechanoreceptors in peripheral neuropathy.

OBJECTIVES: To investigate the properties of mechanoreceptors in patients with peripheral neuropathy. The skin mechanoreceptor is a terminal organ of the primary sensory neuron, which is likely to be affected earlier and more severely than is the nerve trunk by peripheral neuropathies. METHODS: Single sensory unit responses to air-puff and electric stimulation were recorded using the microneurographic technique in the glabrous skin of the hand. Receptor transduction time was estimated by a latency difference between electric- and air-puff-induced responses. RESULTS: A total of 38 mechanoreceptive units were obtained from 14 normal subjects. All the units responded to air-puff stimuli irrespective of the receptor type, and receptor transduction time was approximately 2 ms. A total of 32 units were recorded from 11 patients with neuropathy of variable causes. Seven (22%) of the 32 neuropathic units did not respond to air-puffs despite their ability to respond to electric stimulation. Compared to normal ones, units from patients with peripheral neuropathy had significantly higher mechanical thresholds, but receptor transduction times did not differ significantly. CONCLUSIONS: Changes in receptor properties in human neuropathy are characterized by increased mechanical threshold without prolongation of receptor transduction time, possibly due to a high threshold for generating receptor potentials.

Aged↗

PubMed2002

Liver fibrosis increases the risk of intrahepatic recurrence after hepatectomy for hepatocellular carcinoma.

BACKGROUND: Hepatocellular carcinoma (HCC) commonly develops in patients with chronic hepatitis. Intrahepatic recurrence after hepatectomy often includes nodules of new tumour in the liver remnant. The aim of this study was to examine hepatitis-related factors that might predict this type of recurrence. METHODS: The influence of various hepatitis-related factors on intrahepatic recurrence of HCC was studied by multivariate analysis in 138 patients who underwent curative resection and were followed for more than 2 years. RESULTS: The Cox proportional hazard model showed that histological evidence of fibrosis of the underlying liver was the most significant predictive factor for intrahepatic recurrence (P = 0.001). Serum albumin level was also significantly associated with recurrence (P = 0.038). The relative risks of histological fibrosis and low serum albumin levels were 8.9 and 1.7 respectively. Among tumour-related factors, only tumour size was significantly associated with recurrence (P = 0.017). Major hepatectomy was also an independent risk factor for intrahepatic recurrence (P = 0.004). CONCLUSION: Histological evidence of fibrosis and low serum albumin levels are useful predictors of intrahepatic recurrence after hepatectomy, presumably owing to metachronous multifocal tumour in the liver remnant.

Adolescent↗

PubMed2002

Antibacterial peptide defensin is involved in midgut immunity of the soft tick, Ornithodoros moubata.

Two defensin genes A and B were previously demonstrated to be up-regulated by blood feeding in the soft tick, Ornithodoros moubata [Nakajima et al. (2001) Two isoforms of a member of the arthropod defensin family from the soft tick, Ornithodoros moubata (Acari: Argasidae). Insect Biochem Mol Biol 31: 747-751]. In this study, two defensin isoforms C and D similar to defensins A and B were newly cloned. A total of four defensins have been identified in O. moubata. All four Ornithodoros defensins are coded as prepro-defensins. Ornithodoros defensin genes consist of four exons and three introns, an organization reported in mussel defensins but not insect defensins. Ornithodoros defensin C and D genes are predominantly expressed in the midgut and up-regulated in response to blood feeding. The mature peptide of the previously cloned Ornithodoros defensin A was purified from the midgut lumen, indicating defensin is secreted into the midgut. These findings confirm the involvement of Ornithodoros defensin in midgut immunity.

Amino Acid Sequence↗

PubMed2002

Effect of a human urinary protease inhibitor (Ulinastatin) on respiratory function in pediatric patients undergoing cardiopulmonary bypass.

BACKGROUND: We performed this prospective randomized study to determine the effect of a human urinary protease inhibitor (Ulinastatin) on respiratory function in pediatric patients undergoing cardiopulmonary bypass. METHODS: Twenty-two children were included in this study. They were randomly allocated to 1 of the following groups; a control group (n=11) or a Ulinastatin group (n=11) in which patients received 5000 U/kg of Ulinastatin. Arterial blood samples were obtained before cardiopulmonary bypass (CPB), immediately after CPB, and 30 min after protamine administration, as well as 3 hours after and 18 hours after CPB, and Interleukin-8 and neutrophil elastase concentration were evaluated. RESULTS: CPB time and aortic clamp time did not differ between the groups. Interleukin 8 and neutrophil elastase concentrations before CPB increased significantly immediately after CPB, these concentrations did not differ between the groups. However, neutrophil elastase concentrations of a Ulinastatin group were significantly lower than that of a control group at 30 min after protamine administration (a Ulinastatin group: 1011.3+/-539.1 mg/ml, a control group: 1619.7+/-595.7 mg/ml, p<0.05) and A-aDO2 of a Ulinastatin group was significantly lower than that of a control group at 2 hours after CPB (a Ulinastatin group: 67.1+/-70.6 mmHg, a control group: 169.2+/-116.3 g, p<0.05). CONCLUSIONS: These results suggest that Ulinastatin suppresses the increase in neutrophil elastase and protects the respiratory function in pediatric patients undergoing cardiopulmonary bypass.

Cardiopulmonary Bypass↗

PubMed2002

Pharmacological studies on Puerariae Flos. IV: Effects of Pueraria thomsonii dried flower extracts on blood ethanol and acetaldehyde levels in humans.

We investigated the effects of extracts from the dried flower of Pueraria thomsonii on blood ethanol and acetaldehyde levels in humans consuming alcoholic beverages. The extracts of Pueraria thomsonii had no influence on blood ethanol and acetaldehyde concentration in humans. However, the extracts increased the elimination rate constant of blood acetaldehyde, although they had no effect on the elimination of blood ethanol in humans. These results suggest that Pueraria thomsonii promotes the elimination of blood acetaldehyde in humans. The present study clinically suggests that a modest stimulatory effect of Pueraria thomsonii on the elimination of blood acetaldehyde may passively mitigate acetaldehyde toxicity, such as flushing, palpitation, headache, etc., associated with excessive alcohol intake.

Acetaldehyde↗

PubMed2001

Expression of bone morphogenetic protein-5 gene during chick heart development: possible roles in valvuloseptal endocardial cushion formation.

The bone morphogenetic protein (BMP) family, comprising multifunctional peptide growth factors, regulates many developmental processes in a variety of tissues. We examined the spatiotemporal expression of BMP5 by in situ hybridization in chick embryonic hearts from stages 5 to 33. The BMP5 gene was first expressed in the endoderm underlying the precardiac mesoderm at stages 5 to 8. Thereafter, BMP5 expression was restricted to the myocardium of the atrioventricular (AV) canal and outflow tract (OT) regions, where the valvuloseptal endocardial cushion tissue is induced. These results suggest that BMP5 may play important roles not only in myocardial differentiation, but also in the formation and maintenance of endocardial cushion tissue.

Animals↗

PubMed2001

Crystallization and preliminary X-ray characterization of rat liver acyl-CoA oxidase.

A recombinant form of the flavoenzyme acyl-CoA oxidase from rat liver has been crystallized by the hanging-drop vapour-diffusion technique using PEG 20 000 as a precipitating agent. The crystals grew as yellow prisms, with unit-cell parameters a = 71.05, b = 87.29, c = 213.05 A, alpha = beta = gamma = 90 degrees. The crystals exhibit the symmetry of space group P2(1)2(1)2(1) and are most likely to contain a dimer in the asymmetric unit, with a V(M) value of 2.21 A(3) Da(-1). The crystals diffract to a resolution of 2.5 A at beamline BL6A of the Photon Factory. Two heavy-atom derivatives have been identified.

Acyl-CoA Oxidase↗

PubMed2001

Microcirculation in intestinal villi: a comparison between hemorrhagic and endotoxin shock.

Using intravital microscopy, we studied the effects of hemorrhagic and endotoxin (ETX) shock on the velocity of erythrocytes (red blood cells [RBC]) and the density of perfused villi in mouse small intestine. The mice were divided into four groups: control, normotensive sepsis (a low ETX group, 1.5 mg/kg intravenously), hypotensive sepsis (a high ETX group, 10 mg/kg intravenously), and a hemorrhagic group. One hour after endotoxemia or hemorrhage was induced, mean arterial pressure significantly decreased in the high ETX and hemorrhagic groups (72.5 +/- 1.0 mm Hg in the control group, 71.0 +/- 2.4 in the low ETX group, 42.7 +/- 1.8 in the high ETX group, 43.0 +/- 1.4 in the hemorrhagic group, respectively). We found significant decreases in RBC velocities in the villous tip and capillaries in both ETX groups but not in the hemorrhagic group (in villus tip arteriole, 1.25 +/- 0.02 mm/s, 0.80 +/- 0.02, 0.15 +/- 0.01, 1.20 +/- 0.08; in villus capillaries, 0.55 +/- 0.02, 0.38 +/- 0.02, 0.10 +/- 0.01, 0.61 +/- 0.02, for control, low ETX, high ETX, and hemorrhagic groups, respectively). We also found a significant decrease in the density of RBC-perfused villi in the high ETX and hemorrhagic groups but not in the low ETX or control groups. However, the change in the hemorrhagic group was much less than in the high ETX group (100.0 %, 95.2 +/- 1.6, 32.5 +/- 1.9, 87.3 +/- 3.4, for control, low ETX, high ETX, and hemorrhagic groups, respectively). We concluded that ETX induces a significant decrease in mucosal perfusion characterized by a diminution in RBC velocity and flux in villi found even in a normotensive situation. At a high dose of ETX, these changes are associated with a significant decrease in the number of perfused villi. In addition, we found that at the same level of hypotension, hemodynamics and mucosal perfusion disorders are considerably larger in ETX-induced hypotension than in hemorrhagic hypotension.

Animals↗

PubMed2001

Annexin II overexpression correlates with stromal tenascin-C overexpression: a prognostic marker in colorectal carcinoma.

BACKGROUND: Overexpression of annexin II, a calcium-dependent phospholipid-binding protein, has been reported in various carcinomas. One of its ligands is tenascin-C, an extracellular matrix glycoprotein with predominantly antiadhesive qualities that also has been reported to be a prognostic marker for several carcinomas. In the current study, the authors investigated the correlation between the overexpression of annexin II and tenascin-C in colorectal carcinoma. METHODS: Western blot analysis of annexin II expression was examined in four human colorectal carcinoma cell lines. Using immunohistochemical methods, the authors also examined expression of annexin II and tenascin-C in 105 primary colorectal carcinoma cases. RESULTS: Although annexin II was expressed in human colon carcinoma cell lines, there was no apparent correlation between its expression level and the metastatic potential of these cell lines. The authors observed overexpression of annexin II and tenascin-C proteins in 29.5% and 49.5%, respectively, of colorectal carcinoma cases. Overexpression of annexin II was found to be correlated significantly with histologic type, tumor size, depth of invasion, and pTNM stage, whereas tenascin-C overexpression was noted to be correlated significantly with histologic type, depth of invasion, lymphatic invasion, venous invasion, lymph node metastasis, and pTNM stage. Expression of annexin II was shown to be correlated significantly with that of tenascin-C. Multivariate analysis demonstrated that annexin II and tenascin-C cooverexpression was an independent factor of poor prognosis in patients with colorectal carcinoma. CONCLUSIONS: The data from the current study suggest that both annexin II and tenascin-C are overexpressed in advanced colorectal carcinoma and that they may be related to the progression and metastatic spread of colorectal carcinoma.

Annexin A2↗

PubMed2001

IFN-gamma induces the apoptosis of WEHI 279 and normal pre-B cell lines by expressing direct inhibitor of apoptosis protein binding protein with low pI.

Interferon-gamma plays a crucial role in induction of Th1 response but is predominantly a negative regulator of B cell differentiation and Th2 response, so it is a key molecule in determining cellular or humoral immunity. In this study, we demonstrate that IFN-gamma induces apoptosis in WEHI 279 mouse B cells and IL-7-dependent mouse pre-B cells by disrupting mitochondrial membrane potential and cytochrome c release via down-regulation of Bcl-2 and Bcl-x(L). Furthermore, this apoptotic signal is promoted by the de novo synthesis of endogenous direct inhibitor of apoptosis protein binding protein with low pI (DIABLO) by IFN-gamma and its release from mitochondria into the cytosol. Inhibition of DIABLO expression by antisense oligonucleotide is sufficient to decrease caspase activities and DNA fragmentation, but not cytochrome c release from mitochondria, suggesting that DIABLO plays a critical role in promoting apoptotic signals downstream of mitochondrial events. Thus, these findings demonstrate a signaling pathway during B cell apoptosis induced by IFN-gamma and possible mechanisms by which B cell differentiation is negatively regulated by Th1-type cytokines.

Animals↗

PubMed2001

Linearization and integration of DNA into cells preferentially occurs at intrinsically curved regions from human LINE-1 repetitive element.

A bent DNA library was constructed from human genomic DNA, from which a new clone belonging to the human LINE-1 sequence family was isolated and characterized. This clone, with a length of 378 base pairs and termed HBC-1 (human bent clone-1), contained an intrinsically occurring curved DNA structure. By permutation analysis, the center of curvature of this fragment was mapped onto the nucleotide position 886 from the 5' terminus of the complete LINE-1 sequence. Reporter plasmids, which contain HBC-1, were effectively integrated into human chromosome, indicating that the bent DNA structure provides a preferential donor site for the integration of human LINE-1 sequences. The present finding may provide an explanation as to why some inactivated LINE-1 sequences on human chromosomes carry the deletion at their 5' termini.

3T3 Cells↗

PubMed2001

Neuronal expression of mint1 and mint2, novel multimodular proteins, in adult murine brain.

Mints are multimodular adapter proteins in functioning membrane transport and organization. Mint1 and mint2 are neuron-specific. We localized these isoforms in mouse brain. By in situ hybridization, mRNA encoding mint1 or mint2 was expressed in neurons throughout the brain. Mint1 mRNA expression was greatest in the limbic system including cingulate cortex, hippocampus, anterior thalamic nuclei, medial habenular nucleus, and mammillary body. Mint2 mRNA was rich in cerebral cortex, entorhinal cortex, and hippocampus, but less prominent in other limbic structures. Mint1 mRNA and mint2 mRNA were distributed among hippocampal pyramidal neurons, while mint2 mRNA was especially abundant in CA3. Mint1, but not Mint2 mRNA was abundant in the substantia nigra pars compacta. Immunohistochemistry visualized mint proteins in axon terminals and neuronal somata, generally following mRNA distribution. In the hippocampus, mint1 was rich in the entorhinal projections and mossy fibers of the dentate gyrus, while mint2 was rich in commisural fibers from the contralateral hippocampus and in CA1. Mint1 intensely stained catecholamine-containing neurons such as the substantia nigra pars compacta, ventral tegmental area, and locus ceruleus. Mint2 protein was ubiquitous in these regions. Mint1 and mint2 distribution also differed elsewhere in the brainstem and in the cerebellum. Central nervous system neurons, then, predominantly express either mint1 or mint2. Mints may be involved in synaptic vesicle transport toward the active zone, also participating in transport of certain membrane proteins toward the postsynaptic density. Mint1 and mint2 may divide roles either regionally or depending on neuronal functional characteristics.

Adaptor Proteins, Signal Transducing↗

PubMed2001

The association of K-ras gene mutation and vascular endothelial growth factor gene expression in pancreatic carcinoma.

BACKGROUND: Previously, the authors reported the role of the vascular endothelial growth factor (VEGF) as an angiogenic factor in 40 patients with pancreatic carcinoma. In this study, they investigated the mechanism underlying the regulation of VEGF gene expression and evaluated VEGF expression and K-ras gene status in 48 patients with pancreatic carcinoma. METHODS: The authors used quantitative reverse transcriptase-polymerase chain reaction analysis and direct sequencing techniques for a retrospective study of VEGF gene expression and K-ras gene status in tumor tissue samples from 48 patients with pancreatic carcinoma. Immunohistochemistry also was used to investigate VEGF protein expression. RESULTS: Thirty-one tumors (64.6%) were evaluated with high VEGF expression, and 17 tumors (35.4%) were evaluated with low VEGF expression. Of the 48 primary pancreatic tumors studied, 33 tumors (68.8%) contained mutations of the K-ras gene. There was a significant correlation between VEGF expression and K-ras status. Twenty-five of 33 tumors (75.8%) with mutant K-ras genes showed high VEGF expression, whereas only 6 of 15 tumors with the wild type K-ras (40.0%) showed high VEGF expression (P = 0.038). The mean (+/- standard error) VEGF conservation rate for the 33 tumors with mutant K-ras was 1.839 +/- 1.241, and that for the 15 tumors with wild type K-ras was 1.057 +/- 0.983 (P = 0.037). Furthermore, the median survival for patients with mutant K-ras was shorter than for those with wild type K-ras (10.6 months vs. 27.6 months, respectively; P = 0.026), whereas the median survival for patients with high VEGF expression was shorter compared with that for patients with low VEGF expression (9.5 months vs. 26.4 months, respectively; P = 0.002). Cox regression model analysis indicated that only the VEGF status was a significant factor for prognosis (P = 0.024). Other variables, i.e., K-ras status, histopathologic tumor grade, tumor status, lymph node status, metastatic status, gender, and age at surgery, were not significant. CONCLUSIONS: The results of this study suggest that K-ras oncogene mutation may be associated with VEGF expression and that patients with pancreatic carcinoma who have high VEGF expression are associated with a poor prognosis.

Biomarkers, Tumor↗

PubMed2001

Expression of HNK1 epitope by the cardiomyocytes of the early embryonic chick: in situ and in vitro studies.

Monoclonal antibody HNK1 reacts with a carbohydrate epitope in cell surface glycoproteins and glycolipids. During development, in various species the HNK1 epitopes are expressed in migrating neural crest cells and in the developing conduction cardiomyocytes. The conduction system is generally thought to be developed from cardiomyocytes, but some investigators have hypothesized that it is derived from the neural crest because conduction myocytes express neural antigens, including HNK1. Using immunohistochemistry, we examined the spatiotemporal expression of HNK1 in early chick cardiogenesis (stages 4 to 18) and whether cultured precardiac mesoderm does or does not express HNK1 as well as sarcomeric myosin (MF20). HNK1 was first expressed in the premyocardium at stage 8. At stage 10, HNK1-positive cardiomyocytes were scattered along the straight heart tube. By stage 18, HNK1-positive cardiomyocytes had become restricted to the atrium and sinus venosus. Atrioventricular cushion mesenchyme also expressed an HNK1 epitope. Immunostaining of HNK1 and MF20 in cultured precardiac mesoderm showed that there are at least three types of cells: 1) cardiomyocytes without HNK1 expression, 2) cells possessing both HNK1- and MF20-immunoreactivity, and 3) mesenchymal cells with HNK1. Immunogold electron microscopy showed that cardiomyocytes containing sparsely distributed myofibrils associated with the Z-band react with anti-HNK1 antibody. Our observations showed a direct evidence for the first time that the precardiac mesoderm generates HNK1-positive cardiomyocytes with morphological features similar to those of conduction cardiomyocytes.

Animals↗