Biomedical subjects

H Takano

Publications and source records attributed to H Takano.

At least 91 records · Page 5Linked to original sources

PubMed2000

Cyclooxygenase-2 mediates the cardioprotective effects of the late phase of ischemic preconditioning in conscious rabbits.

We examined the role of cyclooxygenase-2 (COX-2) in the late phase of ischemic preconditioning (PC). A total of 176 conscious rabbits were used. Ischemic PC (six cycles of 4-min coronary occlusions/4-min reperfusions) resulted in a rapid increase in myocardial COX-2 mRNA levels (+231 +/- 64% at 1 h; RNase protection assay) followed 24 h later by an increase in COX-2 protein expression (+216 +/- 79%; Western blotting) and in the myocardial content of prostaglandin (PG)E(2) and 6-keto-PGF(1alpha) (+250 +/- 85% and +259 +/- 107%, respectively; enzyme immunoassay). Administration of two unrelated COX-2 selective inhibitors (NS-398 and celecoxib) 24 h after ischemic PC abolished the ischemic PC-induced increase in tissue levels of PGE(2) and 6-keto-PGF(1alpha). The same doses of NS-398 and celecoxib, given 24 h after ischemic PC, completely blocked the cardioprotective effects of late PC against both myocardial stunning and myocardial infarction, indicating that COX-2 activity is necessary for this phenomenon to occur. Neither NS-398 nor celecoxib lowered PGE(2) or 6-keto-PGF(1alpha) levels in the nonischemic region of preconditioned rabbits, indicating that constitutive COX-1 activity was unaffected. Taken together, these results demonstrate that, in conscious rabbits, up-regulation of COX-2 plays an essential role in the cardioprotection afforded by the late phase of ischemic PC. Therefore, this study identifies COX-2 as a cardioprotective protein. The analysis of arachidonic acid metabolites strongly points to PGE(2) and/or PGI(2) as the likely effectors of COX-2-dependent protection. The recognition that COX-2 mediates the antistunning and antiinfarct effects of late PC impels a reassessment of current views regarding this enzyme, which is generally regarded as detrimental.

6-Ketoprostaglandin F1 alpha↗

PubMed2000

Epidermal growth factor (EGF) in the goat uterus: immunohistochemical localization of EGF and EGF receptor and effect of EGF on uterine activity in vivo.

This study examined the distribution of immunoreactive epidermal growth factor (EGF) and EGF receptor (EGF-R) in the uterus and the effects of EGF on uterine activity in goats. Immunohistochemistry of EGF and EGF-R in the uteri showed distinct staining in the luminal and glandular epithelium and slight to moderate staining in the stromal and myometrial cells. To examine possible roles of the EGF system in the regulation of uterine activity, pressure changes in the intrauterine balloon were determined after intraluminal infusion of EGF into the uterine horn. Either at estrus or diestrus (9 to 14 days after the first day of estrus), treatment with 1 or 5 microg of EGF gradually reduced uterine activity, whereas infusion of the vehicle alone had no effect. The maximum reduction in uterine activity was seen 4 h after the treatment with 1 microg of EGF (40% to 45% reduction in the area surrounded by the contraction curve and its baseline), and the activity slowly returned thereafter. These results suggest that EGF in the uterus may play a role in regulating uterine activity in goats.

Animals↗

PubMed2000

Electrochemically modulated liquid chromatography coupled on-line with electrospray mass spectrometry.

Electrochemically modulated liquid chromatography (EMLC) has been coupled to an electrospray mass spectrometer. This combination takes advantage of the ability of EMLC to manipulate retention and enhance separation efficiency solely through changes in the potential applied to a conductive stationary phase, thereby minimizing complications because of possible changes in analyte ionization efficiencies when gradient elution techniques are used. Three examples are presented that demonstrate the attributes of this EMLC/electrospray mass spectrometry (ES-MS) coupling. The first two examples involve the separation of mixtures of corticosteroids or of benzodiazepines, showing the general utility of the union for eluent identification and low-level detection. The ability to identify products from on-column redox transformations is also demonstrated using the benzodiazepine mixture. The third example investigates the electrooxidation of aniline by utilizing an EMLC column as an on-line electrochemical reactor and product separator and ES-MS for detection and product identification.

Adrenal Cortex Hormones↗

PubMed2000

Properties of gastric smooth muscles obtained from mice which lack inositol trisphosphate receptor.

Membrane potential recordings, made from the circular smooth muscle layer of the gastric antrum taken from mutant mice which lacked the inositol trisphosphate (InsP3) type 1 receptor, were compared with those obtained from the stomach of control (wild-type) mice. Immunostaining of gastric muscles indicated that the distribution and form of c-kit positive cells were similar in wild-type and mutant mice. Smooth muscles from wild-type mice generated slow waves that in turn initiated spike potentials, while those from mutant mice were either quiescent or generated irregular bursts of spike potentials. In the presence of nifedipine, slow waves with reduced amplitude were generated in wild-type mice, while all electrical activity was abolished in mutant mice. Acetylcholine depolarized and sodium nitroprusside hyperpolarized the membrane in muscles from both types of mice, being more effective in wild-type mice. Noradrenaline produced similar hyperpolarizations in both types of mice. Transmural nerve stimulation evoked inhibitory junction potentials (IJPs) in both wild-type and mutant mice. In wild-type mice, the IJPs were reduced in amplitude by nitroarginine and converted to a cholinergic excitatory junction potential (EJP) by apamin. In mutant mice, the IJPs were unaffected by nitroarginine or atropine but were abolished by apamin. It is concluded that in antral smooth muscle, the expression of InsP3 type 1 receptors may be causally related to the generation of slow waves but not to the generation of action potentials. A lack of InsP3 receptors attenuates cholinergic excitatory and nitrergic inhibitory responses but does not alter the response to noradrenaline.

Acetylcholine↗

PubMed2000

In vivo conformation of mitochondrial DNA revealed by pulsed-field gel electrophoresis in the true slime mold, Physarum polycephalum.

Pulsed-field gel electrophoresis (PFGE) was used to examine the in vivo and in vitro conformations of Physarum polycephalum mitochondrial DNA (mtDNA). We used plugs containing isolated mitochondria, isolated mitochondrial nucleoids (mt-nuclei), and isolated mtDNA, in addition to whole cells. The mtDNA contained in the myxamoebae, plasmodia, isolated mitochondria, and isolated mt-nuclei was circular, but most of the isolated mtDNA had been site-specifically fragmented and linearized during DNA preparation and storage under low ionic strength conditions. Restriction mapping of Physarum mtDNA by the direct digestion of the isolated mt-nuclei from two different strains, DP89 x AI16 and KM88 x AI16, resulted in the circular form. A linear mitochondrial plasmid, mF, is known to promote mitochondrial fusion and integration of itself into the mtDNA in Physarum. Linearization of mtDNA by the integration of the mF plasmid was demonstrated when we used PFGE to analyze isolated mitochondria from the plasmodial strain DP89 x NG7 carrying the mF plasmid (mF+). The PFGE system can be used not only to determine whether the form of mtDNA is linear or circular but also to analyze the dynamic conformational changes of mtDNA.

Animals↗

PubMed2000

Mmh/Ogg1 gene inactivation results in accumulation of 8-hydroxyguanine in mice.

The major mutagenic base lesion in DNA caused by exposure to reactive oxygen species is 8-hydroxyguanine or 7, 8-dihydro-8-oxoguanine (8-OH-G). Products of the human MMH/OGG1 gene are known to catalyze in vitro the reactions repairing this DNA lesion. To analyze the function of Mmh in vivo, we generated a mouse line carrying a mutant Mmh allele by targeted gene disruption. Mmh homozygous mutant mice were found to have a physically normal appearance, but to have lost nicking activity in liver extracts for substrate DNA containing 8-OH-G, exhibiting a 3-fold increased accumulation of this adduct at 9 weeks of age compared with wild-type or heterozygous mice. Further elevation to 7-fold was observed in 14-week-old animals. Substantial increase of spontaneous mutation frequencies was clearly identified in Mmh mutant mice bearing transgenic gpt genes. These results indicate that exposure of DNA to endogenous oxidative species continuously produces the mutagenic adduct 8-OH-G in mice, and Mmh plays an essential role in repair of this DNA damage.

Animals↗

PubMed2000

Impairment of antigen-presenting cell function in mice lacking expression of OX40 ligand.

OX40 expressed on activated T cells is known to be an important costimulatory molecule on T cell activation in vitro. However, the in vivo functional significance of the interaction between OX40 and its ligand, OX40L, is still unclear. To investigate the role of OX40L during in vivo immune responses, we generated OX40L-deficient mice and a blocking anti-OX40L monoclonal antibody, MGP34. OX40L expression was demonstrated on splenic B cells after CD40 and anti-immunoglobulin (Ig)M stimulation, while only CD40 ligation was capable of inducing OX40L on dendritic cells. OX40L-deficient and MGP34-treated mice engendered apparent suppression of the recall reaction of T cells primed with both protein antigens and alloantigens and a significant reduction in keyhole limpet hemocyanin-specific IgG production. The impaired T cell priming was also accompanied by a concomitant reduction of both T helper type 1 (Th1) and Th2 cytokines. Furthermore, antigen-presenting cells (APCs) derived from the mutant mice revealed an impaired intrinsic APC function, demonstrating the importance of OX40L in both the priming and effector phases of T cell activation. Collectively, these results provide convincing evidence that OX40L, expressed on APCs, plays a critical role in antigen-specific T cell responses in vivo.

Animals↗

PubMed2000

Mapping of a particular element using an absorption edge with an X-ray fluorescence imaging microscope.

An X-ray fluorescence imaging microscope with a Wolter-type objective mirror (magnification: 13) has been constructed at beamline 39XU of SPring-8. Monochromatic X-rays (DeltaE/E approximately 10(-4)) in the energy range 6-10 keV were used for X-ray fluorescence excitation of the specimens. Using two monochromatic X-rays above and below the absorption edge of a particular element, a two-dimensional image of the element could be obtained. As a result, two-dimensional element mapping of the test specimens (Cu, Co, Ni, Fe and Ti wires) and constituent minerals (Fe, Mn and Ti) of a rock specimen (a piemontite-quartz schist) became possible.

Journal Article↗

PubMed2000

In vitro DNA fragmentation of mitochondrial DNA caused by single-stranded breakage related to macroplasmodial senescence of the true slime mold, Physarum polycephalum.

We found that mitochondrial DNA (mtDNA) isolated from Physarum polycephalum fragmented itself in weak ionic solutions. The mtDNA was dissolved in STE (saline Tris-EDTA: 150 mM NaCl, 10 mM Tris-HCl, 1 mM EDTA), TE (10 mM Tris-HCl, 1 mM EDTA) and DW, and then electrophoresed in an agarose gel. The intact 86-kbp mtDNA band was seen in STE, but several novel bands appeared in TE and DW. In TE, two discrete bands appeared at 6.7-kbp (alpha-band) and 5.0-kbp (beta-band), whereas at least 17 discrete bands were observed in distilled water (DW). These fragmentation patterns were not stoichiometric, as seen when using restriction endonucleases, but were clearly different from the degradation of DNA caused by a physical shearing force or a contaminating nuclease. In this paper, we characterize this in vitro fragmentation of mtDNA from P. polycephalum. We located 19 fragments, including the alpha and beta fragments, on a mtDNA restriction map, and demonstrated that these cleavage sites were S1 nuclease-sensitive regions, which are single-stranded DNA regions such as nicks and gaps in the mtDNA. The alpha and beta fragments are derived from the region encoding ribosomal RNAs (rRNAs) and the ATP synthase (atpA) gene, while the other 17 fragments are not derived from any specific region, but the cleavage sites are located throughout the mtDNA molecule. In P. polycephalum, it is well known that the growth rate of macroplasmodia decreases with aging. Equal amounts of mtDNA from juvenile and aged macroplasmodia were electrophoresed and the frequency of the beta fragment in each sample was measured. The ratio of the beta band to the total signal including background was estimated to be 3.3-4.0% in juvenile macroplasmodia, whereas it increased to 8.3-28.2% in aged macroplasmodia. This result suggests that the in vitro fragmentation of mtDNA is associated with macroplasmodial senescence. The single-stranded breakage of mtDNA of P. polycephalum may accumulate with age.

Aging↗

PubMed2000

A putative mitochondrial ftsZ gene is present in the unicellular primitive red alga Cyanidioschyzon merolae.

Two ftsZ homologues were isolated from the unicellular primitive red alga Cyanidioschyzon merolae (CmftsZ1 and CmftsZ2). Phylogenetic analysis revealed that CmftsZ1 is most closely related to the ftsZ genes of alpha-Proteobacteria, suggesting that it is a mitochondrial-type ftsZ gene, whereas CmftsZ2 is most closely related to the ftsZ genes of cyanobacteria, suggesting that it is a plastid-type ftsZ gene. Southern analysis indicates that CmftsZ1 and CmftsZ2 are both single-copy genes located on chromosome XIV in the C. merolae genome. Northern analysis revealed that both CmftsZ1 and CmftsZ2 are transcribed, and accumulate specifically before cell and organelle division. The results of Western analysis suggest that CmFtsZ1 is localized in mitochondria.

Amino Acid Sequence↗

PubMed2000

Thromboxane A2 receptor-mediated tonic contraction is attributed to an activation of phosphatidylcholine-specific phospholipase C in rabbit aortic smooth muscles.

Thromboxane A2 (TXA2) analogue STA2 produced a tonic contraction in rabbit aortic smooth muscles. In the present study, we examined phosphatidylcholine (PC) hydrolysis as a signaling pathway for the tonic contraction in rabbit aortic smooth muscles. In the primary cultured cells labeled with [3H]choline, STA2 caused an accumulation of [3H]phosphorylcholine, a metabolite of PC by PC-specific PLC, in a concentration-dependent manner. The accumulation of [3H]phosphorylcholine was inhibited by SQ29548, a TXA2 receptor antagonist. In the muscle strips, STA2-induced tonic contraction was potently inhibited by D609, an inhibitor of PC-specific phospholipase C in a concentration-dependent manner with the IC50 of about 10 microM. Norepinephrine-induced tonic contraction was also inhibited by D609 with a weaker potency. These results strongly suggest that stimulation of TXA2 receptor results in the activation of PC-specific phospholipase C to yield diacylglycerol that contributes to the tonic contraction.

Animals↗

PubMed2000

Empty sella syndrome in nevoid basal cell carcinoma syndrome.

We reported the magnetic resonance imaging of four young patients (13 to 19 years) with nevoid basal cell carcinoma syndrome (NBCCS), which showed empty sella, agenesis of the corpus callosum and empty sella, an interhemispheric lipoma with callosal dysgenesis, and an arachnoid cyst in the posterior fossa, respectively. Calcification of the diaphragma sellae, which is a protective barrier against the pulsating action of the cerebrospinal fluid, may cause the empty sella in NBCCS.

Adolescent↗

PubMed2000

Dissecting thoracoabdominal aortic aneurysm associated with an isolated right-sided aortic arch.

Although a right-sided aortic arch is not a rare anomaly, an aortic dissection involving an isolated right-sided aortic arch is extremely rare and remains a complicated entity for surgical therapy because of its anatomical characteristics. Previous reports that we have identified in English literature include only six surgical cases of aortic dissection involving a right-sided aortic arch. We report on a 75-year-old female who had a chronic thoracoabdominal aortic aneurysm following type B aortic dissection in a right-sided aortic arch. Graft replacement including reconstruction of Adamkiewicz artery and a celiac trunk was performed. The postoperative course was uneventful except for a prolonged ventilatory support. This case seems to be the first successful case of extended graft replacement for this pathology.

Aged↗

PubMed2000

The safety and usefulness of cool head-warm body perfusion in aortic surgery.

OBJECTIVE: To determine the safety and usefulness of antegrade hypothermic cerebral perfusion in conjunction with mild hypothermic (tepid) visceral perfusion (so-called cool head-warm body perfusion; CHWB) in aortic surgery; the clinical outcomes and perioperative data on this new technique were retrospectively analyzed. METHODS: From January 1990 to March 1999, 59 patients underwent ascending aorta or aortic arch surgery using antegrade selective cerebral perfusion (SCP). Three perfusion techniques, differentiated by perfusion temperature, were used, those being deep hypothermia (DH; nasopharyngeal temperature of 20 degrees C, n=14), moderate hypothermia (MH; nasopharyngeal temperature of 28 degrees C, n=17) and CHWB (nasopharyngeal temperature of 25 degrees C and bladder temperature of 32 degrees C, n=28). Selection of the technique largely followed a chronological pattern, in this order: DH, MH and, more recently, CHWB. The three groups were retrospectively compared in terms of operative outcome, duration of cardiopulmonary bypass (CPB) and operation, and intraoperative blood loss. RESULTS: The early (within 30 days after surgery) mortality/hospital mortality (including operative mortality) was 7.1/21.4, 5.9/11.8 and 3.6/7.1% in the DH, MH and CHWB groups, respectively. The rate of stroke was 7.1, 6.3 and 3.6% in the DH, MH and CHWB groups, respectively. No statistical difference was found in early or hospital mortality, or in the rate of stroke among the three groups. The CPB time, especially the time for rewarming, was significantly shorter in the CHWB than in the DH group. Likewise, the operation time, especially the time after CPB, was significantly shorter in the CHWB than in the DH and MH groups. Blood loss was significantly less in the CHWB than in the DH group. CONCLUSION: Our data suggest that CHWB perfusion in aortic surgery is a safe and useful technique in shortening the operation time and reducing blood loss, but further prospective study is necessary.

Aged↗

PubMed2000

Multiple mycotic arch-thoraco-abdominal aortic aneurysms: a successful case of in situ graft replacement.

Mycotic aortic aneurysms are an uncommon yet still life-threatening pathology. We report on a 67-year-old male who had a persistent fever and back pain. Contrast enhanced computed tomography (CT) showed multiple aortic aneurysms located in the aortic arch, the descending thoracic aorta and the supraceliac abdominal aorta. After 2 months of antibiotic therapy, a staged operation was carried out with 2-week interval, which includes a graft replacement of aortic arch with elephant trunk technique and a graft replacement of thoraco-abdominal aorta with omental transfer. The postoperative course was uneventful. This case seems to be quite rare in terms of multiplicity and location of mycotic aneurysms. Surgical strategy for this pathology is discussed.

Aged↗

PubMed2000

Carbon-source-dependent transcriptional control involved in the initiation of cellular differentiation in Streptomyces griseus.

Carbon source is one of the environmental factors that affects cellular differentiation of Streptomyces. We have identified the craA gene as a putative negative regulator involved in the carbon-source-dependent initiation of cellular differentiation in Streptomyces griseus. Carbon-source-dependent transcriptional repression of craA, which is caused by binding of a putative repressor protein to its promoter region, is proposed to result in the initiation of aerial mycelium formation. The presence of a craA homologue in the chromosome of Streptomyces coelicolor A3(2) implicates the existence of a similar regulatory mechanism in this organism. The repression of craA-promoter activity in glucose media could be alleviated not only by replacing glucose with maltose but also by supplying copper, which suggests that the stimulatory effect of copper on cellular differentiation in Streptomyces is excerted via abolishment of glucose-repression of craA.

Amino Acid Sequence↗

PubMed2000

Cytoprotection by metallothionein against gastroduodenal mucosal injury caused by ethanol in mice.

Metallothionein (MT) is a small, cysteine-rich protein that can act as a free radical scavenger at least in vitro. To test the hypothesis that MT participates in gastroduodenal cytoprotection, we studied sensitivity to gastroduodenal mucosal injury caused by ethanol in MT-null mice that have null mutations in MT-I and MT-II genes. MT-null mice and wild-type mice were orally treated with ethanol (60% or 99.5%, 0.2 ml/mouse). The macroscopic gastric lesion indices were significantly higher in MT-null mice than in wild-type mice 90 minutes after ethanol treatment. Histopathological examination in ethanol-treated MT-null mice showed vacuolar degeneration, necrosis of the epithelial cells, and hemorrhage throughout the tunica mucosa. Moreover, the duodenum also showed morphologic changes, including marked degeneration and coagulative necrosis of the entire villi, desquamation of the degenerated epithelial cells, and hemorrhage. In contrast, histopathologic changes were less prominent in the wild-type mice treated with ethanol. MT was not detected either in the stomach or duodenum of MT-null mice, whereas gastric and duodenal zinc contents were not significantly different between MT-null mice and wild-type mice. These results provide direct evidence that intrinsic MT plays a cytoprotective role in gastroduodenal mucosal injury caused by ethanol.

Animals↗

PubMed2000

Preprimed artificial lung for emergency use.

We investigated the possibility of preprimed storage of an artificial lung (AL), aiming at facilitating its emergency use. Test ALs, consisting of a special microporous hollow fiber membrane made of polyolefin in which direct blood-gas contact was completely eliminated, were preprimed with saline solution, sterilized by gamma-ray irradiation, and evaluated after 1-3 months of storage at room temperature. A small amount of bubble was noted in the priming solution after storage in some ALs, which most likely originated from the air dissolved in the priming solution or persisted in the liquid compartment at priming. Although the preprimed solution contained several polyolefin-breakdown products due to irradiation, including ethyl alcohol, n- and t-butyl alcohol, acetone, and carbon dioxide, the levels of these substances were at concentrations known to be not toxic. Endotoxin concentration was negligible. In SEM observation, no perceptible microstructural change was observed in the hollow fibers after preprimed storage. Maximum tensile stress and ultimate elongation of the hollow fiber in the test ALs were reduced by approximately 20% and 3%, respectively, from those of the control AL. The influence of preprimed storage on gas-exchange function was examined in a venoarterial bypass animal study using a goat. Oxygen transfer function was well preserved whereas carbon dioxide removal function was slightly lowered according to the storage term in the stored ALs compared with those of a nonpreprimed control AL. On the basis of these results, we conclude that preprimed storage of the AL with gamma-ray sterilization is basically feasible and realistic.

1-Butanol↗