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Biomedical subjects

H Takano

Publications and source records attributed to H Takano.

At least 55 records · Page 3Linked to original sources
PubMed2001

A(1) or A(3) adenosine receptors induce late preconditioning against infarction in conscious rabbits by different mechanisms.

We investigated whether activation of A(1) or A(3) adenosine receptors (ARs) induces late preconditioning (PC) against infarction in conscious rabbits using the selective AR agonists 2-chloro-N(6)-cyclopentyladenosine (CCPA) and N(6)-3-iodobenzyladenosine-5'-N-methylcarboxamide (IB-MECA). In vitro radioligand binding and cAMP assays demonstrated CCPA to be approximately 200- to 400-fold selective for the rabbit A(1)AR and IB-MECA to be approximately 20-fold selective for the rabbit A(3)AR. We observed that (1) pretreatment of rabbits 24 hours earlier with CCPA (100 microgram/kg IV bolus) or IB-MECA (100 or 300 microgram/kg) resulted in an approximately 35% to 40% reduction in the size of the infarct induced by 30 minutes of coronary artery occlusion and 72 hours of reperfusion compared with vehicle-treated rabbits, whereas pretreatment with the selective A(2A)AR agonist CGS 21680 (100 microgram/kg) had no effect; (2) the delayed cardioprotective effect of CCPA, but not that of IB-MECA, was completely blocked by coadministration of the highly selective A(1)AR antagonist N-0861; (3) inhibition of nitric oxide synthase (NOS) with N(omega)-nitro-L-arginine during the 30-minute occlusion abrogated the infarct-sparing action of CCPA but not that of IB-MECA; and (4) inhibition of ATP-sensitive potassium (K(ATP)) channels with sodium 5-hydroxydecanoate during the 30-minute occlusion blocked the cardioprotective effects of both CCPA and IB-MECA. Taken together, these results indicate that activation of either A(1)ARs or A(3)ARs (but not A(2A)ARs) elicits delayed protection against infarction in conscious rabbits and that both A(1)AR- and A(3)AR-induced cardioprotection involves opening of K(ATP) channels. However, A(1)AR-induced late PC uses an NOS-dependent pathway whereas A(3)AR-induced late PC is mediated by an NOS-independent pathway.

Adenine↗
PubMed2001

Transcriptional activation of the human HMG1 gene in cisplatin-resistant human cancer cells.

The nonhistone chromosomal protein, high mobility group 1 (HMG1), which is ubiquitously expressed in higher eukaryotic cells, preferentially binds to cisplatin-modified DNA. The observation that HMG1 is overexpressed in cisplatin-resistant human cancer cells suggests that cisplatin resistance may be closely associated with HMG1. To decipher the mechanism of HMG1 overexpression in cisplatin-resistant cells, we isolated two overlapping genomic DNA clones containing the entire human HMG1 gene. These clones, which span approximately 15 kb of contiguous DNA, include 5 kb of the 5' flanking region as well as the entire coding sequence. We sequenced 1500 bp upstream of the first exon. The segment proximal to the transcription initiation site did not contain a TATA box but did possess an activating transcription factor site, an activator protein-2 site, one CCAAT box, and two CCAAT-binding transcription factor/nuclear factor-1 (CTF/NF-1) sites. HMG1 promoter activity was 3-10-fold higher in cisplatin-resistant KB-CP20 cells than in parental KB cells. An in vivo footprint experiment showed several differences of dimethyl sulfate modifications between KB and KB-CP20 cells in the area around the CTF/NF-1 sites. In addition, electrophoretic gel mobility shift assays showed that binding of a nuclear factor from cisplatin-resistant cells to the CTF/NF-1 site was significantly higher than the binding of the same factor from parental cells. Semiquantitative reverse transcription-PCR and Western blot analysis also showed that expression of CTF/NF-1 was 3-20-fold higher in the resistant cell line than in its parental counterpart. These findings suggest that, in cisplatin-resistant cells, the expression of HMG1 gene product is enhanced at the transcriptional level and that this probably occurs through the enhanced expression of the CCAAT binding factor, CTF/NF-1.

Antineoplastic Agents↗
PubMed2001

Origin and propagation of spontaneous excitation in smooth muscle of the guinea-pig urinary bladder.

The origin and propagation of waves of spontaneous excitation in bundles of smooth muscle of the guinea-pig bladder were examined using intracellular recording techniques and visualization of the changes in the intracellular calcium concentration ([Ca2+]i). Bladder smooth muscle cells exhibited spontaneous transient increases in [Ca2+]i which originated along a boundary of each smooth muscle bundle and then spread to the other boundary with a conduction velocity of 2.0 1r1r>mm1> s-1. Spontaneous increases in [Ca2+]i were always preceded by action potentials. Nifedipine (10 microM) abolished increases in both [Ca2+]i and action potentials. Caffeine (10 1s1sFmM1F), ryanodine (50 microM) and cyclopiazonic acid (10 microM reduced the amplitude of the associated increases in [Ca2+]i without preventing the generation of action potentials. Spontaneous action potentials had conduction velocities of 40 1t1t>mm 1> s-1 in the axial direction and 1.3 1u1u>mm 1> s-1 in the transverse direction. The electrical length constants of the bundles of muscle were 425 microM in the axial direction and 12.5 microM in the transverse direction. Neurobiotin, injected into an impaled smooth muscle cell, spread more readily to neighbouring cells located in the axial direction than those located in the transverse direction. The spread of neurobiotin was inhibited by 18beta-glycyrrhetinic acid (18beta-GA, 40 microM), a gap junction blocker. Immunohistochemistry for Connexin 43 showed abundant punctate staining on the smooth muscle cell membranes. These results suggested that spontaneous action potentials and associated calcium waves occur almost simultaneously along the boundary of bladder smooth muscle bundles and then propagate to the other boundary probably through gap junctions.

Action Potentials↗
PubMed2001

Detection of human papillomaviruses in cervical neoplasias using multiple sets of generic polymerase chain reaction primers.

OBJECTIVE: The aim of this study was to evaluate precisely the differences in the spectra of human papillomavirus (HPV) types detected by different generic primer pairs commonly used for detection of this extraordinarily heterogeneous virus. METHODS: Three sets of polymerase chain reaction (PCR) primers for the L1 open reading frame (ORF) and two sets for E6/E7 ORFs were used to detect HPVs in DNAs from 107 cervical tissues, including 77 cervical neoplasias. HPV types were determined by analysis of restriction fragment length polymorphisms (RFLPs) and nucleotide sequencing. RESULTS: A high overall detection rate of HPV in cervical neoplasias (76/77, 98.7%) was achieved by polymerase chain reaction (PCR) amplification with multiple sets of generic primers, while the detection rate for each individual primer pair varied from 48/77 (62%) to 70/77 (91%). Only in 34 of 77 cases (44%) were HPV DNAs positive for all sets of primer pairs. Further determination of HPV types by RFLPs and nucleotide sequencing showed inconsistencies between the PCR primer pairs used. CONCLUSION: Our study revealed that the HPV detection rate is critically affected by the choice of PCR primers, and that appropriate use of combinations of generic PCR primer sets followed by RFLP analyses is both necessary and sufficient for typing most HPVs in cervical lesions. More precise methods such as sequencing would be necessary in only a few cases.

Consensus Sequence↗
PubMed2001

Magnetic resonance imaging in the evaluation of vaginal foreign bodies in a young girl.

A 7-year-old girl with foul-smelling, bloody vaginal discharge for more than 2 years was initially suspected of suffering from vaginal foreign bodies. Although plain radiography revealed no abnormal findings in the pelvis, magnetic resonance imaging (MRI) showed multiple low intensity objects and an intact vaginal wall. Four plastic toys were removed with forceps under general anesthesia. MRI is supposed to be the best technique for evaluating vaginal foreign bodies in young girls.

Child↗
PubMed2001

The complete DNA sequence of the mitochondrial genome of Physarum polycephalum.

The complete sequence of the mitochondrial DNA (mtDNA) of the true slime mold Physarun polycephalum has been determined. The mtDNA is a circular 62,862-bp molecule with an A+T content of 74.1%. A search with the program BLAST X identified the protein-coding regions. The mitochondrial genome of P. polycephalum was predicted to contain genes coding for 12 known proteins [for three cytochrome c oxidase subunits, apocytochrome b, two F1Fo-ATPase subunits, five NADH dehydrogenase (nad) subunits, and one ribosomal protein], two rRNA genes, and five tRNA genes. However, the predicted ORFs are not all in the same frame, because mitochondrial RNA in P. polycephalum undergoes RNA editing to produce functional RNAs. The nucleotide sequence of an nad7 cDNA showed that 51 nucleotides were inserted at 46 sites in the mRNA. No guide RNA-like sequences were observed in the mtDNA of P. polycephalum. Comparison with reported Physarum mtDNA sequences suggested that sites of RNA editing vary among strains. In the Physarum mtDNA, 20 ORFs of over 300 nucleotides were found and ORFs 14 19 are transcribed.

Amino Acid Sequence↗
PubMed2001

Senescent cells are resistant to death despite low Bcl-2 level.

Cellular senescence may be an antioncogenic event. Bcl-2 is a product of the oncogene, bcl-2, but it may also participate in cellular senescence. To investigate the role of Bcl-2, we analyzed the level of Bcl-2 during aging of normal human fibroblasts by immunoblot analysis and found that its level was highly suppressed in four normal senescent fibroblast strains. This result suggests that senescent cells are more sensitive to induction of death than young cells. Nevertheless, senescent cells showed more resistance to death induced by hydrogen peroxide than young cells, according to LDH assay. Because the balance among antiapoptotic and proapoptotic proteins is an important factor for the determination of cell death, we examined levels of other Bcl-2 family and apoptosis-regulating proteins, but observed no reasonable change to explain the resistance. During the course of the death induction experiment, we obtained results showing that growth-arrested cells were also resistant to death, and this was further confirmed by a BrdU-labeling experiment. As senescent cells are stopped permanently in the G0/G1-phase of the cell cycle, our data strongly suggest that this is the cause of resistance to death in senescent cells.

Apoptosis↗
PubMed2001

Architecture of baked breads depicted by a magnetic resonance imaging.

The architecture of baked breads made of fresh dough and frozen dough was depicted by magnetic resonance imaging (MRI). Pieces of bread (16 mm cubic cakes) were soaked in organic solvents containing various concentrations of heavy metals (Cu(2+), Co(2+) and Fe(3+)) and images of the grain structure of the breads were obtained. Of the organic solvents tested, acetone was preferable because of its single peak that prevents chemical shift effects on images, the retention of the bread structure, and the solubility of heavy metals. The heavy metals, especially Fe(3+), shortened the overly long relaxation times of acetone to practical lengths for imaging and stained the materials to provide high contrasts. The images obtained in acetone with 8 mM Fe(3+) were suitable for analyzing crumb grain structures. The bread of fresh dough showed a uniform distribution of pores of various sizes made of thin gluten sheets, whereas the pores in the bread of frozen dough were less, prominently large, non-uniformly distributed, and made of thick gluten sheets.

Bread↗
PubMed2001

Renal macrostructure and cortical circulation in hypertension assessed by dynamic computed tomography.

The aim of this study was to assess the macrostructure of the kidney and the grade of heterogeneity in renal cortical circulation in the early stages of essential hypertension. The subjects consisted of 84 patients (<50 years old) who underwent dynamic computed tomography (CT) because of various abdominal diseases and who had no serious hemodynamic abnormalities. The volumes of the whole kidney, cortex, and medulla were measured with the program installed in the CT instrument. In dynamic CT under appropriate conditions, the CT number of each pixel (image element) reflects the blood volume in the pixel. The means and standard deviations were calculated from the CT numbers within the renal cortex. The coefficient of variation (CV) of CT numbers was used as the index of the heterogeneity of renal cortical circulation. The volume ratio of cortex/medulla was significantly (P < .01) smaller in the hypertensive patients (0.80 +/- 0.03 (mean +/- SE)) than in the normotensive subjects (0.92 +/- 0.03). The CV was significantly (P < .01) greater in the hypertensives (n = 23, 0.124 +/- 0.008) than in the normotensives (n = 61, 0.106 +/- 0.003). There was a significant correlation (r = -0.391, P < .001) between the CV of CT numbers and the volume ratio of cortex/medulla, and the relationship between the two variables was independent of other variables. These results suggest that the heterogeneity of renal cortical circulation is increased in the early stages of essential hypertension and is related to changes in renal macrostructure.

Adult↗
PubMed2001

Macrophage inflammatory protein-1alpha relates to the recruitment of inflammatory cells in myosin-induced autoimmune myocarditis in rats.

In experimental autoimmune myocarditis (EAM) there is a characteristic initial focal inflammatory response in the myocardium, induced mainly by CD4(+) T cells and macrophages, which leads to massive myocardial damage. Macrophage inflammatory protein-1alpha (MIP-1alpha) induces chemotaxis in lymphocytes, eosinophils, basophils, and macrophages. We assessed the potential role of MIP-1alpha in the pathogenesis of EAM in rats immunized with porcine myosin. Following immunization, the levels of MIP-1alpha mRNA in EAM showed an increase on Day 11 and peaked on Day 17. MIP-1alpha-positive cells were predominantly immunoreactive to OX6 antibody (dendritic cells) and ED2 antibody (resident macrophages) by Day 14. Marked cellular infiltration was seen on Day 17 with the major population of MIP-1alpha-positive cells also positive for ED1 (inflammatory macrophages). We then examined the association of MIP-1alpha with the development of myocardial inflammation. Rats were divided into three groups: Group A consisted of EAM rats (n = 10); Group B consisted of EAM rats treated with anti-MIP-1alpha (1 mg/kg) on Days 11, 13, and 15, before the onset of initial inflammation (n = 5); and Group C consisted of EAM rats treated with anti-MIP-1alpha from the start of the initial inflammation on Days 14, 16, and 18 (n = 5). Rats were euthanized on Day 21 and three transverse sections of the heart were prepared to determine the percentage of the area affected by inflammatory lesions. This area of inflammation was significantly smaller in Group B (27 +/- 4%) than in Groups A (51 +/- 6%) or C (50 +/- 6%) (p < 0.01), indicating that the administration of antibody before the initiation of inflammation, in part, will inhibit myocardial inflammation. These data suggest that MIP-1alpha may play an important role in the recruitment of inflammatory cells in the early stages of EAM.

Animals↗
PubMed2001

Change in vasoconstrictive function during prolonged nonpulsatile left heart bypass.

We investigated changes in vasoconstrictive function accompanying prolonged nonpulsatile left heart bypass (NLHB). After 2-week pulsatile left heart bypass (PLHB) in 11 goats, NLHB was conducted for another 4 weeks (Group N) in 6 goats. In the other 5 goats, PLHB was continued for another 4 weeks (Group P). Systemic vascular resistance at rest (rSVR) was measured on the last days of the second and sixth postoperative week (W2 and W6, respectively). Subsequently, phenylephrine was injected, and the maximum values (SVRmax) and the maximum increasing change in SVR (DeltaSVR) were measured. No significant difference was observed in rSVR between groups at W2 or W6. The SVRmax and the DeltaSVR at W2 were consistent in both groups. However, at W6, the SVRmax and the DeltaSVR of Group N were significantly lower than those of Group P. In conclusion, prolonged NLHB caused a significant decrease in the SVR response to phenylephrine, indicating a dimunition of vasoconstrictive function.

Animals↗
PubMed2001

Application of indirect flow rate measurement using motor driving signals to a centrifugal blood pump with an integrated motor.

The method of measuring the flow rate of a centrifugal blood pump from the input electric power, which will be indispensable for the long-term use of such devices, was developed and was applied to the direct-driven centrifugal blood pump that has been developed by our research group. The accuracy was evaluated in a chronic animal experiment using an adult goat. The results demonstrated that this method carries the sufficient potential of the instantaneous monitoring method, but errors due to electromagnetic and mechanical losses were not determined always precisely. The detection of adverse phenomena such as the obstruction of the inlet cannula was also possible from the estimated value of the flow rate and its waveform pattern.

Animals↗
PubMed2001

Acute changes in plasma levels of hepatocyte growth factor during low-density lipoprotein apheresis.

Hepatocyte growth factor (HGF) is a mesenchyme-derived pleiotropic factor, and angiogenesis is included in a variety of its functional effects. HGF levels were measured in 5 sessions of low-density lipoprotein (LDL) apheresis in 3 patients with severe hypercholesterolemia. Blood was collected at the start (T0) and at 1,000 ml (T1), 2,000 ml (T2), and 3,000 ml (T3) plasma treatments. During LDL apheresis, HGF levels increased from 1.59 +/- 0.78 (mean +/- SE, n = 5) ng/ml at T0 to 6.64 +/- 0.97 at T1, 6.28 +/- 0.97 at T2, and 5.20 +/- 0.94 at T3. In one apheresis session, HGF increased immediately at the 100 ml plasma treatment stage. HGF was adsorbed completely by a dextran-sulfate (DS) column. Despite the adsorption by the DS column, HGF in the patient blood increased to the levels with functional effects. The improvement of ischemic symptoms due to LDL apheresis may be related to the angiogenic activities of HGF.

Analysis of Variance↗
PubMed2001

Dynamic helical CT-guided needle localization of non-palpable and mammographically occult breast lesions. Case reports.

Dynamic helical CT-guided needle localization of non-palpable and mammographically occult breast lesions is described. Dynamic helical CT-technique enabled fast volume scanning of the whole breast during the early contrast enhancement phase, which provided sufficient contrast to localize the target lesions. The procedures were successfully completed without complications.

Biopsy, Needle↗
PubMed2001

Expression of proteinases and inflammatory cytokines in subchondral bone regions in the destructive joint of rheumatoid arthritis.

OBJECTIVE: We previously described abnormalities in the bone marrow of patients with rheumatoid arthritis (RA), but were able to shed little light on the pathogenic roles of inflammatory cytokines and proteinases in joint destruction in the subchondral region in RA. This is the first report to describe the co-localization of cytokines and proteinases in this area. METHODS: Decalcified paraffin-embedded sections from 10 patients with RA and five patients with osteoarthritis (OA) were examined for the immunolocalization of cathepsins B, K and L and the localization of messenger RNAs for interleukin 1beta (IL-1beta), tumour necrosis factor alpha (TNF-alpha) and matrix metalloproteinase 9 (MMP-9). The cells were double-stained with anti-CD68 or anti-prolyl 4-hydroxylase (PH) antibody. RESULTS: An immunohistochemical study confirmed the expression of cathepsins B and L by CD68-positive mononuclear cells at the sites of significant cartilage and bone erosion from the subchondral region in all RA specimens. Osteoclast-like cells showed intense staining for cathepsin K and MMP-9. Osteoblast-like cells strongly expressed MMP-9. Analysis of serial sections revealed that expression of the IL-1beta and TNF-alpha genes occurred near that of the cathepsins and MMP-9 in the subchondral region. CONCLUSION: We conclude that inflammatory cytokines and tissue-damaging proteinases play important roles in joint destruction in the subchondral region in RA.

Adult↗
PubMed2001

Active transepithelial transport of irinotecan (CPT-11) and its metabolites by human intestinal Caco-2 cells.

Irinotecan (CPT-11) is a camptothecin analog with low (about 10--20%) and variable oral bioavailability in animal models. Here, Caco-2 cells were used to evaluate the transepithelial transport of CPT-11 and its metabolites. Caco-2 cells demonstrated significant expression of P-glycoprotein (P-gp), multidrug resistance-associated protein and canalicular multispecific organic anion transporter. Both the lactone and carboxylate forms of CPT-11 and SN-38 were actively transported across the cell monolayers, mainly by the apical-localized P-gp pump. Cellular permeability of CPT-11 at a concentration of 17 microM converted from active to passive-diffusional transport between the 2 and 6 h exposure time points. Antiproliferative effects of CPT-11 were related to permeability of the lactone form, whereas for SN-38 efficacy was dependent on lactone accumulation. Exposure of CPT-11 with cyclosporin A significantly enhanced its efficacy, whereas this was not observed with verapamil and R101933. In contrast, SN-38 efficacy decreased in the presence of P-gp inhibitors due to active transport toward the basolateral side, thereby reducing drug accumulation. Hence, multiple-active transport systems could be demonstrated to be responsible for not only accumulation profiles but also cytotoxic efficacy of CPT-11 and SN-38 in the intestinal Caco-2 cells. It is suggested that CPT-11 might act in a time-dependent manner and that SN-38-mediated cytotoxicity relates to (dose-dependent) lactone kinetics. The results detailed in this report could contribute toward the development of a clinically useful oral formulation of CPT-11 with improved absorption characteristics and suggest that cyclosporin A is a suitable agent for further research of this concept.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2001

Change of muscle motor-evoked potentials after motor cortex stimulation caused by acute spinal cord injury in cats.

The validity of the evoked compound muscle action potential (ECMAP) as an index of spinal cord injury has not been established in neurophysiologic monitoring of motor function, although evoked spinal cord potential (ESCP) has been. In the current study, nine cats were used. After craniotomy, electric stimuli were applied to the motor area. Four cats were given stimulation of various numbers and frequencies, and the other five cats underwent graded compression of the spinal cord, and then ECMAPs and ESCPs were recorded. Three cats were awakened and their motor functions were assessed 3 weeks later. The amplitude of the ESCP never decreased to 60% or less of the control value, even when ECMAPs disappeared. No motor dysfunction was present 3 weeks after the experiment. ECMAP is clinically useful, providing information on impairments of the spinal cord that otherwise would remain undetected.

Action Potentials↗