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Biomedical subjects

H Otani

Publications and source records attributed to H Otani.

At least 55 records · Page 3Linked to original sources

Cerebral protection during surgery for aortic arch aneurysms.

Surgical repair of aneurysms or dissections involving the transverse aortic arch and the distal aortic arch carries a considerable risk of cerebral complications. Currently, deep hypothermic circulatory arrest (DHCA), moderate hypothermic circulatory arrest or DHCA with selective cerebral perfusion (SCP) and DHCA with retrograde cerebral perfusion (RCP) are used as means to protect the central nervous system. DHCA alone is simple, but the safe time of DHCA is limited. RCP is an alternative technique for cerebral protection that can prolong the safe time of DHCA. SCP offers virtually unlimited time in isolating cerebral circulation. With the improvement of cardiopulmonary bypass (CPB) materials and myocardial preservation, DHCA with SCP is our current preference of an adjunct for cerebral protection, although possible increment of mortality and morbidity associated with a prolonged DHCA and CPB remains to be overcome.

Aged↗

Vacuolar H(+)-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts in cultured human saphenous vein.

BACKGROUND: The molecular mechanism of neointimal hyperplasia after vein graft surgery remains elusive. Vacuolar H(+)-ATPase (V-ATPase) is involved in intracellular trafficking and may play a crucial role in neointimal cell growth. METHODS AND RESULTS: Cultured human saphenous vein segments developed neointimal formation within 10 days. Neointimal cells were positive for vimentin and alpha-smooth muscle actin but negative for desmin, which is indicative of myofibroblasts. Those myofibroblasts were found to have originated from periadventitial fibroblasts, which upregulated the expression of 16-kDa proteolipid of V-ATPase before proliferation and phenotypic modulation. Neointimal myofibroblast growth and survival were highly sensitive to inhibition of V-ATPase by bafilomycin A(1) (BA(1)), because the incorporation of [(3)H]thymidine into the myofibroblasts was significantly inhibited by nanomolar concentrations of BA(1) and apoptotic cell death was induced by a similar concentration range of BA(1). In contrast, endothelial cells and differentiated smooth muscle cells were resistant to apoptosis by BA(1). CONCLUSIONS: These results suggest that V-ATPase plays a crucial role in growth and phenotypic modulation of myofibroblasts that contributes to neointimal formation in cultured human saphenous vein.

Adult↗

Myocardial protection by preconditioning of heart with losartan, an angiotensin II type 1-receptor blocker: implication of bradykinin-dependent and bradykinin-independent mechanisms.

BACKGROUND: Ischemic preconditioning (PC) represents a state-of-the-art technique for myocardial preservation. Although certain intracellular mediators have been shown to play a role in PC, the exact nature of the trigger for PC is not known. Our previous study demonstrated that intracellular bradykinin released from the heart during ischemia/reperfusion plays a role in myocardial preservation. This study was undertaken to further examine the mechanism of bradykinin-mediated PC. METHODS AND RESULTS: Since the bradykinin B(2) receptor is likely to provide cardioprotection by blocking angiotensin II formation, we determined the effects of an angiotensin II type 1 (AT(1)) receptor blocker, losartan, and a bradykinin B(2) receptor blocker, HOE 140, on myocardial protection. Isolated rat hearts were perfused initially by the Langendorff mode with Krebs-Henseleit buffer (KHB) for 15 minutes in the absence (control) or presence of losartan (4.5 micromol/L) and/or HOE 140 (10 micromol/L). After conversion to the working mode for 10 minutes (baseline), randomly assigned control and experimental hearts were subjected to 30 minutes of normothermic global ischemia followed by 2 hours of reperfusion. Myocardial function, infarct size, cardiomyocyte apoptosis, and amount of bradykinin/angiotensin released from the hearts were measured at baseline and during reperfusion while in the working mode. Significant postischemic ventricular recovery was demonstrated by improved developed pressure and aortic flow and reduced myocardial infarct size and apoptotic cell death with losartan, whereas the reverse was true for HOE 140. The functional recovery and infarct size-lowering ability of losartan were partially blocked and the antiapoptotic function of losartan was completely blocked by HOE 140. CONCLUSIONS: The results document that losartan reduced whereas HOE 140 increased myocardial ischemia/reperfusion injury by blocking AT(1) and bradykinin B(2) receptors, respectively, suggesting a role of the bradykinin B(2) receptor in PC. Losartan provided cardioprotection through both bradykinin-dependent and bradykinin-independent mechanisms.

Adrenergic beta-Antagonists↗

Expression of the long form of leptin receptor (Ob-Rb) mRNA in the brain of mouse embryos and newborn mice.

The long form of the leptin receptor (Ob-Rb) has a cytoplasmic domain which activates the JAK-STAT signal transduction pathway. It is related to appetite and energy expenditure and is expressed in various parts of the brain in adults. In embryos, however, the detailed distribution of Ob-Rb expression sites and the function of the leptin-Ob-Rb system remain unclear, although leptin is detected in human cord plasma and leptin mRNA is detected in mouse embryos. In this study, we investigated the Ob-Rb mRNA expression pattern in the brains of mouse embryos and newborn mice by RT-PCR and in situ hybridization. At embryonic day 10.5 (E10.5), Ob-Rb mRNA was already detected in the brain by RT-PCR. By in situ hybridization, Ob-Rb mRNA was observed in the ventricular zone of the rhombencephalon at E11.5. At E12.5, it was also expressed in the ventricular zone of the telencephalon, mesencephalon and cerebellar primordium. From E14. 5 it was expressed in the cortical plate of the telencephalon and the ventricular zone of the thalamus. At E16.5, it was expressed in the premamillary hypothalamic nucleus, superficial gray matter of the superior colliculus, external germinal and Purkinje cell layers of the cerebellum, and facial nucleus. At E18.5, it was expressed in the arcuate nucleus and ventromedial hypothalamic nucleus. These results suggest that the leptin-Ob-Rb system is related to brain development.

Animals↗

Cardiac fibrosis in mice lacking brain natriuretic peptide.

Cardiac fibrosis, defined as a proliferation of interstitial fibroblasts and biosynthesis of extracellular matrix components in the ventricles of the heart, is a consequence of remodeling processes initiated by pathologic events associated with a variety of cardiovascular disorders, which leads to abnormal myocardial stiffness and, ultimately, ventricular dysfunction. Brain natriuretic peptide (BNP) is a cardiac hormone produced primarily by ventricular myocytes, and its plasma concentrations are markedly elevated in patients with congestive heart failure and acute myocardial infarction. However, its precise functional significance has been undefined. In this paper, we report the generation of mice with targeted disruption of BNP (Nppb(-/-) mice). We observed multifocal fibrotic lesions in the ventricles from Nppb(-/-) mice. No signs of systemic hypertension and ventricular hypertrophy are noted in Nppb(-/-) mice. In response to ventricular pressure overload, focal fibrotic lesions are increased in size and number in Nppb(-/-) mice, whereas no focal fibrotic changes are found in wild-type littermates (Nppb(+/+) mice). This study establishes BNP as a cardiomyocyte-derived antifibrotic factor in vivo and provides evidence for its role as a local regulator of ventricular remodeling.

Animals↗

Long-term right ventricular volume overload increases myocardial fluorodeoxyglucose uptake in the interventricular septum in patients with atrial septal defect.

BACKGROUND: Several studies have shown that long-term right ventricular (RV) overload in animal models alters myocardial energy substrate metabolism. However, whether long-term RV volume overload alters this metabolism in the human is unclear. METHODS AND RESULTS: We performed positron emission tomography with [(18)F]fluorodeoxyglucose (FDG) and single-photon emission tomography (SPECT) with [(201)Tl]TlCl (Tl) and [(123)I]15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) in 11 patients with atrial septal defect (ASD) and 11 control subjects. In the FDG study, we calculated myocardial metabolic rate of glucose (MMR) in interventricular septum (IVS) and left ventricular (LV) free wall. MMR was significantly increased in IVS compared with LV free wall in the ASD patients (420+/-35 versus 333+/-32 mol x kg(-1) x min(-1); P<0.05) but not in the control group (347+/-27 versus 357+/-25 mol x kg(-1) x min(-1)). In both ASD and control groups, SPECT count was not significantly different between IVS and LV free wall in Tl (ASD, 160+/-11 versus 177+/-12; control, 141+/-12 versus 157+/-14 counts per 15 minutes) and BMIPP studies (ASD, 203+/-14 versus 212+/-18; control, 162+/-16 versus 176+/-16 counts per 15 minutes). MMR in the IVS/LV free wall ratio in the ASD group significantly correlated with indices related to RV volume overload. CONCLUSIONS: Given the assumption that long-term RV volume overload did not affect the lumped constant, the present study suggests that, unlike myocardial perfusion or fatty acid analogue uptake, myocardial glucose utilization in IVS relative to LV free wall is increased in relation to long-term RV volume overload in patients with ASD.

Adult↗

Angiotensin II type 1 receptor blockade abolishes specific K(ATP)channel gene expression in rats with myocardial ischemia.

The cardiac ATP-sensitive potassium (K(ATP)) channel is potentially composed of an inward rectifier potassium channel (Kir6.1 and/or Kir6.2) subunit and the cardiac type of sulfonylurea receptor (SUR2A). We reported that cardiac Kir6.1 mRNA and protein are specifically upregulated in the non-ischemic as well as the ischemic regions in rats with myocardial ischemia, suggesting that humoral and/or hemodynamic factors are responsible for this regulation. In the present study, pretreatment with TCV-116, an angiotensin (Ang) II type 1 receptor antagonist, completely inhibited the upregulation of Kir6.1 mRNA and protein expression in both regions of rat hearts subjected to 60 min of coronary artery occlusion followed by 24 h of reperfusion; whereas pretreatment with lisinopril, an Ang converting enzyme (ACE) inhibitor, partly inhibited this upregulation. Except for rats pretreated with TCV-116, Kir6.1 mRNA levels were positively correlated with those for brain natriuretic peptide (BNP), a molecular indicator of regional wall stress, in both the non-ischemic and the ischemic regions. Plasma Ang II levels were not elevated in rats with control myocardial ischemia compared with sham rats. Thus, the stress-related induction of cardiac Kir6.1 mRNA and protein expression under myocardial ischemia is inhibited by pretreatment with an AT1 antagonist, but also in part by an ACE inhibitor, suggesting that activation of local renin-angiotensin system may play a role.

Angiotensin I↗

Pulmonary sequestration associated with aspergillosis.

Pulmonary sequestration involves an abnormal pulmonary tissue separated from the normal pulmonary parenchyma, not connected to the tracheobronchial tree and supplied by a systemic artery. A case of intralobar pulmonary sequestration is presented. Case; a 49-year-old male was admitted to our hospital complaining of fever, cough and sputum production. Sputum culture resulted in a large growth of Aspergillus niger. Angiography showed an abnormal blood supply from the abdominal aorta to the right lower lobe. Right lower lobectomy was performed. The postoperative courses are uneventful.

Aspergillosis↗

Mitral valve plasty using artificial chordae in a 1.5-year-old boy with congenital mitral stenosis and absent anterolateral chordae.

A 1.5-year-old boy with refractory heart failure due to congenital mitral stenosis exhibited fusion of the anterolateral leaflets associated with moderate mitral regurgitation due to absent anterolateral chordae. Fused leaflets were incised and the mitral valve opening improved. Mitral regurgitation increased due to the absence of chordae, so 2 pairs of artificial chordae of 5-0 expanded polytetrafluoroethylene suture were anchored to the hypoplastic anterolateral papillary muscle, then attached to the free margin of incised leaflets. Postoperative examination showed improved mitral opening without exacerbated mitral regurgitation.

Artificial Organs↗

Bypass graft material and myocardial protective procedure in combined coronary artery bypass grafting and valve surgery.

OBJECTIVE: The aortic cross clamping time is prone to be longer when coronary artery bypass grafting (CABG) is combined with valve surgery. Therefore, the myocardium that is revascularized by in-situ internal thoracic artery graft is at risk to ischemia, and, myocardial protection is especially important in such operation. In this study, the effect of myocardial preservation of combined antegrade, retrograde and terminal warm blood cardioplegia during combined valve surgery and CABG using the internal thoracic artery as a bypass conduit was evaluated. METHODS: From November 1992 to August 1999, 15 patients received combined CABG and valve surgery. Among these 15 patients, 13 patients who did not need hemodialysis were divided into 2 groups, and a comparative study was done. In Group I (n = 5), only the saphenous vein graft was employed for combined CABG and valve surgery, and myocardial protection was done by combined antegrade and terminal warm blood cardioplegia. In Group II (n = 8), at least 1 in-situ internal thoracic artery graft was employed for CABG and valve surgery, and myocardial protection was done by combined antegrade, retrograde and terminal warm blood cardioplegia. RESULTS: Despite longer aortic cross clamping time in Group II, the peak creatine kinase-MB of Group II was significantly lower. In addition, the postoperative administration of dopamine tended to be less in Group II. CONCLUSION: Myocardial protection by combined antegrade, retrograde and terminal warm blood cardioplegia may be an effective adjunct to combined valve surgery and CABG employing the in-situ internal thoracic artery graft.

Aged↗

Freehand cryopreserved mitral valve allograft with flexible ring in the pig.

OBJECTIVE: Cryopreserved valve allografts have proven satisfactory in aortic and pulmonary positions but not mitrally because of the difficulty in properly aligning the mitral valve allograft due to the complex subvalvular apparatus. To make the surgical procedure easier, we developed a freehand cryopreserved mitral valve allograft with a flexible ring. METHODS: Whole cryopreserved mitral valve allografts with the papillary muscle, chordae, and leaflets from donor pigs were implanted mitrally in recipient pigs under cardiopulmonary bypass divided into 2 experimental groups; control allografts without the ring (n = 6) (CA group) and allografts with a flexible ring (n = 7) (RA group). Postimplantation hemodynamics and valvular function were evaluated by measuring arterial pressure, left ventricular end diastolic pressure, and left atrial pressure and by evaluating 2-dimensional echocardiography. Allografts were evaluated pathohistologically after cryopreservation and surgery by light microscopy. RESULTS: Hemodynamics did not differ significantly between groups. Aortic cross-clamping and Cardiopulmonary bypass times were significantly shorter in the RA group than the CA group (p < 0.05). Pigs requiring optional procedures with sutured annuloplasty and valvuloplasty numbered more in the CA group than the RA group. Postoperative echocardiography showed satisfactory mitral valve opening in diastole and good leaflet coaptation in systole in both groups. Light microscopic examination of cryopreserved allografts after surgery showed almost normal structures. CONCLUSIONS: Acute hemodynamic function and morphology of freehand cryopreserved valve allografts implanted mitrally in pigs proved acceptable. Adaptation of the flexible ring to allografts might be useful for technical benefit to facilitate accurate positioning of mitral subvalvular apparatus at implantation.

Animals↗

The properties of the Kir6.1-6.2 tandem channel co-expressed with SUR2A.

Functional ATP-sensitive K (KATP) channels have an octameric subunit structure with four pore-forming subunits (Kir6.x) and four sulfonylurea receptors (SURx). In the present study, the properties of the heteromeric KATP channel whose pore subunits are composed of Kir6.1 and Kir6.2 were examined using a heterologous expression system. In COS7 cells co-transfected with Kir6.1, Kir6.2 and SUR2A at a ratio of 1:1:2, KATP channels showed various unitary conductances between those of Kir6.1/SUR2A (33.6+/-4.2 pS) and Kir6.2/ SUR2A (67.1+/-1.6 pS). Kir6.1-6.2 tandem protein, constructed by fusing the C-terminus of Kir6.1 to the N-terminus of Kir6.2 with a ten glutamine linker sequence, also formed a channel with an intermediate conductance (58.9+/-1.5 pS). Kir6.2 and Kir6.1-6.2 showed similar sensitivity to ATP4-: half-maximal inhibition (IC50) was obtained at 14.1+/-12.8 microM and 17.6+/-9.6 microM, respectively. In the presence of Mg2+, Kir6. 1-6.2 was significantly less sensitive than Kir6.2 to MgATP (IC50=95.5+/-49.6 microM versus 18.9+/-5.0 microM). These results suggest that Kir6.1 and Kir6.2 are endowed with the potential to form a heteromeric KATP channel, which has a low sensitivity to MgATP.

Adenosine Triphosphate↗

Alteration of the membrane lipid environment by L-palmitoylcarnitine modulates K(ATP) channels in guinea-pig ventricular myocytes.

Sarcolemmal adenosine 5'-triphosphate-sensitive K+ channels (K(ATP)) are dramatically up-regulated by a membrane phospholipid, phosphatidyl-inositol-4,5-bisphosphate (PIP2). During ischaemia, L-palmitoylcarnitine (L-PC), a fatty acid metabolite, accumulates in the sarcolemma and deranges the membrane lipid environment. We therefore investigated whether alteration of the membrane lipid environment by L-PC modulates the K(ATP) channel activity in inside-out patches from guinea-pig ventricular myocytes. L-PC (1 microM) inhibited KATP channel activity, without affecting the single channel conductance, through interaction with Kir6.2. L-PC simultaneously enhanced the ATP sensitivity of the channel [concentration for half-maximal inhibition (IC50) fell from 62.0+/-2.7 to 30.3+/-5.5 microM]. In contrast, PIP2 attenuated the ATP sensitivity (IC50 343.6+/-54.4 microM) and restored Ca2+-induced inactivation of KATP channels (94.1+/-13.7% of the control current immediately before the Ca2+-induced inactivation). Pretreatment of the patch membrane with 1 microM L-PC, however, reduced the magnitude of the PIP2-induced recovery to 22.7+/-6.3% of the control (P<0.01 vs. 94.1+/-13.7% in the absence of L-PC). Conversely, after the PIP2-induced recovery, L-PC's inhibitory action was attenuated, but L-PC partly reversed the PIP2-mediated decrease in the ATP sensitivity (IC50 fell from 310+/-19.2 to 93.1+/-9.8 microM). Thus, interaction between L-PC and PIP2 in the plasma membrane appears to regulate K(ATP) channels.

Adenosine Triphosphate↗

Reconstructing the pathway of the tensor veli palatini motor nerve during early mouse development.

The motor axons innervating the tensor veli palatini (TVP) navigate a long distance from the trigeminal motor nucleus to their target. The pathway and time course of the TVP motor nerve during this navigation process remain poorly understood. The aim of this study was to elucidate the peripheral development of the TVP motor nerve, and to confirm when the morphological relationship is established between the nerve and target muscle progenitors. Using immunohistochemistry, carbocyanine fluorescent labeling, and computerized three-dimensional image-reconstruction methods, we demonstrated the development of the TVP motor nerve in mouse embryos. Further, the morphological relationship between the extending mandibular nerve and myogenic cells stained for MyoD1 was examined. The peripheral pathfinding of the TVP motor nerve was divided into three continuous stages: (1) the earliest trigeminal motor axons leave the metencephalon and enter the primordium of the trigeminal ganglion at E9.5, when MyoD1-positive cells can already be detected in the mesenchymal core of the mandibular arch; (2) converging with the sensory root, the trigeminal motor root excites the trigeminal ganglion and begins to approach the mandibular muscle precursors at E10.5; (3) collateral branching occurs at E12.5. By E13.5, a nerve branch splits from the mandibular nerve to innervate the TVP, which appears as an individual muscle mass. These results suggest that the early process of mandibular motor nerve extension is correlated with the trigeminal ganglion cells, whereas when growing out of the ganglion, the mandibular nerve has a close relationship with target myogenic cells throughout the later process of pathway finding.

Acetylcholinesterase↗

Successful palliation of hypoactive delirium due to multi-organ failure by oral methylphenidate.

Delirium is frequently observed in terminally ill cancer patients, but complete remission is often difficult to achieve. Therefore, symptom palliation is of great importance to improve patients' quality of life. Although it has been suggested that psychostimulants would be beneficial to patients with hypoactive delirium, there have been very few empirical reports so far. We report on a terminally ill cancer patient with hypoactive delirium caused by multi-organ failure, in whom methylphenidate was effective in improving the ability to maintain communication. This case highlights the efficacy of methylphenidate for hypoactive delirium in terminally ill cancer patients.

Central Nervous System Stimulants↗

Fate of fibrin sealant in pericardial space.

BACKGROUND: Although fibrin sealant (Beriplast, Aventis Behring, Marburg, Germany) has been widely used as a supplementary measure for hemostasis during cardiac surgery in Europe and is becoming popular in the United States, the pharmocokinetics of fibrin sealant applied in pericardial space has not been elucidated. METHODS: A small incision was made on the epicardial surface of the left ventricle of a rat, and the incision was sutured. Total 0.2 ml of fibrin sealant containing iodine 125 (125I)-labeled fibrinogen, aprotinin, blood coagulation factor XIII and thrombin was applied to the area around the suture line. RESULTS: Distributions of 125I-labeled fibrinogen in the heart on postoperative days 1, 3, 7, and 14 were 48.2% +/- 1.8%, 20.7% +/- 2.2%, 0.15% +/- 0.02%, and 0.01% +/- 0.02%, respectively. The radioactivity was negligible in the blood, liver, spleen, and kidney except for the thyroid in which the radioactivity increased to 7.9% +/- 0.7% and 4.3% +/- 0.4%, respectively, on postoperative days 7 and 14. Iodine 125-labeled fibrinogen concentrations of the heart and other organs showed a similar change in the time course of distribution. Dense and thick fibrin network, observed on postoperative day 1, had dissipated and was thinner with collagen formation by postoperative day 7. CONCLUSIONS: Fibrin sealant applied to the pericardial cavity regresses rapidly and plays an important role in wound healing.

Animals↗

Potential role of vacuolar H-adenosine triphosphatase in neointimal formation in cultured human saphenous vein.

OBJECTIVE: Vacuolar H(+)-adenosine triphosphatase plays a pivotal role in pH regulation and molecular transport across the vacuolar membranes and is involved in cell proliferation and transformation. In the present study, possible involvement of vacuolar H(+)-adenosine triphosphatase in neointimal formation was investigated in an organ culture model of human saphenous vein. METHODS AND RESULTS: Cultured saphenous vein segments developed neointimal formation and marked thickening of the media within 14 days. Neointimal formation and medial thickening were completely inhibited by 10 nmol/L bafilomycin A(1), a selective inhibitor of vacuolar H(+)-adenosine triphosphatase, although structurally related macrolide antibiotics FK-506 and erythromycin were without an effect. The neointimal cells were positive for alpha-smooth muscle actin and vimentin but negative for desmin, indicative of myofibroblasts. The emergence of myofibroblasts was inhibited, and endothelial cells were preserved in the saphenous vein segments treated with bafilomycin A(1). Uptake of bromodeoxyuridine, a proliferation marker, by myofibroblasts was abrogated in the saphenous vein segments treated with 10 nmol/L bafilomycin A(1). Detection of apoptotic cells by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling concomitant with identification of desmin-expressing smooth muscle cells demonstrated that neointimal myofibroblasts, but not medial smooth muscle cells, that expressed desmin underwent apoptosis by treatment with bafilomycin A(1). CONCLUSIONS: These results suggest that vacuolar H(+)-adenosine triphosphatase may be involved in myofibroblast growth that contributes to neointimal formation and medial thickening in cultured human saphenous vein. Increased sensitivity of myofibroblasts, but not endothelial cells, and differentiated smooth muscle cells to bafilomycin A(1) may have potential therapeutic implications in the treatment for vein graft disease.

Actins↗

Mouse Ror2 receptor tyrosine kinase is required for the heart development and limb formation.

BACKGROUND: A mouse receptor tyrosine kinase (RTK), mRor2, which belongs to the Ror-family of RTKs consisting of at least two structurally related members, is primarily expressed in the heart and nervous system during mouse development. To elucidate the function of mRor2, we generated mice with a mutated mRor2 locus. RESULTS: Mice with a homozygous mutation in mRor2 died just after birth, exhibiting dwarfism, severe cyanosis, and short limbs and tails. Whole-mount in situ hybridization analysis showed that mRor2 was expressed in the branchial arches, heart and limb/tailbuds, in addition to the developing nervous system. The mutants had cardiac septal defects, mainly a ventricular septal defect. In addition, an examination of the skeletal systems revealed that the mutants had shorter limbs, vertebrae and facial structure, with a particular defect in their distal portions, and that almost no calcification was observed in their distal limbs. Histological examination showed abnormalities in the chondrocytes. CONCLUSIONS: Our findings suggest that mRor2 plays essential roles in the development of the heart and in limb/tail formation, in particular cardiac septal formation and ossification of distal portions of limbs and tails.

Animals↗