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Biomedical subjects

H Takano

Publications and source records attributed to H Takano.

At least 361 records · Page 20Linked to original sources
PubMed1993

Effect of aging of recipient oocytes on the development of bovine nuclear transfer embryos in vitro.

The present study was undertaken to examine the effect of the length of in vitro maturation of oocytes on the efficiency of enucleation, parthenogenetic activation and blastomere fusion by electric stimulus. In vitro development of reconstituted oocytes receiving a blastomere from 8 to 16-cell bovine embryos fertilized in vitro was investigated to assess the effect of aging of the oocytes. The proportion of oocytes with a first polar body at 22 to 24 hours after maturation was high (80%) compared with those obtained at 16 to 18, 28 to 30 or 42 to 44 hours (50 to 75%). The success rate of enucleation significantly decreased with aging (88, 85, 74 and 55%). The activation rate significantly increased with the length of maturation in vitro (P<0.01) (1 to 4, 24 to 41, 57 to 70 and 80 to 87%). The proportion of oocytes fused with a blastomere from 8- to 16-cell embryos was not dependent on the age of the oocytes (54 approximately 59%). The ability of the reconstituted oocytes to develop to the 2-cell and the 8- to 16-cell stage increased with the length of maturation of recipient oocytes. When oocytes enucleated and a blastomere at 22 to 24 hours were incubated further for 22 to 23 hours until electrofusion. The proportions of oocytes which developed to the 2-cell and the 8- to 16-cell stages (74 and 17%) were similar to those obtained at 42 to 44 hours after maturation. However, only 1 to 6% of reconstituted eggs receiving a blastomere from 8- to 16-cell embryos fertilized in vitro developed into a blastocyst in vitro.

Journal Article↗
PubMed1993

Functional properties of the allotypes of mouse complement regulatory protein, factor H: difference of compatibility of each allotype with human factor I.

Three allotypes of mouse factor H, H.1, H.2, and H.3 were purified from the sera of mice with different factor H allotypes, and their functional properties were investigated. The three allotypes all bound to heparin, DNA, Con A, and methylamine-treated mouse C3 (C3(MA)mo) with similar affinities for each protein immobilized, showed identical mobilities on SDS-PAGE, and were reacted well with rabbit polyclonal antibody against H.1 and H.2. Factor I-cofactor activity of these factor H allotypes was measured using highly purified material of mouse, guinea-pig, and human origin. In a homologous system, these allotypes expressed indistinguishable mouse factor I (Imo)-cofactor activity for the cleavage of C3(MA)mo. Imo-cofactor activity was again indistinguishable in these allotypes when methylamine-treated human C3 (C3(MA)hu) or methylamine-treated guinea-pig C3 (C3(MA)gp) was substituted for the C3(MA)mo substrate. The cofactor activity of these factor H allotypes, however, was augmented 4-5 times if C3(MA)hu) was used instead of C3(MA)mo, and was barely detected if C3(MA)gp was employed. In contrast, differences in the potency of the cofactor activity for the three allotypes were revealed if human factor 1 (Ihu) was substituted for Imo: the order of the efficiency for the cleavage of C3(MA)hu was H.2 > H.1 = H.3. These results, taken together with the finding that the homologous combinations of mouse and human factors H and I expressed greater activity for the cleavage of C3(MA)hu than did the heterologous combinations of factor H and factor I, suggest that mouse factor H allotypes discriminate species of protease factor I but not those of substrate (C3(MA), and H.2 possesses the best compatibility for Ihu in C3(MA)hu inactivation.

Animals↗
PubMed1993

Evaluation of left ventricular function utilizing transesophageal echocardiography during and after thoracic aortic aneurysm repair.

This study was designed to evaluate left ventricular (LV) function during aortic cross-clamping (ACC) by comparing left heart bypass (LHB) with a centrifugal pump and simple aortic cross-clamping (SC). The end-diastolic volume index (EDVI), ejection fraction (EF), fractional shortening (FS) and end-systolic meridional stress (ESS) were measured by transesophageal echocardiography. The measurements were performed 1) before ACC, 2) 2 min after ACC, 3) 20 min after ACC, 4) 2 min after unclamping and 5) 1 h after unclamping. With cross-clamping, a significant decrease was observed in both EDVI (108 vs 83 ml/m2) and EF (73 vs 67%) in patients with LHB. Patients utilizing SC showed a sustained increase in ESS (43 vs 64 10(3) dyne/cm2). The systolic blood pressure did not vary during LHB, but a transient increase occurred in patients with SC. With release of the cross-clamping, EDV and EF returned to the baseline values in patients with LHB. A significant decrease occurred in EDVI (101 vs 71 ml/m2) and ESS (61 vs 36 10(3) dyne/cm2) in the SC group. We conclude that circulatory support with LHB may offer greater stability of the LV function during thoracic aortic cross-clamping than SC because of the lower preload and afterload.

Aged↗
PubMed1993

Evidence that acrosin activity is important for the development of fusibility of mammalian spermatozoa with the oolemma: inhibitor studies using the golden hamster.

The sperm plasma membrane over the equatorial segment of the acrosome gains the ability to fuse with the oolemma some time during, or after, the acrosome reaction. Since acrosin is a major component of the acrosome matrix that dissolves during the acrosome reaction, we sought to determine the effect of acrosin inhibitors on the sperm's ability to fuse with the oolemma. Five acrosin inhibitors (soybean trypsin inhibitor (SBTI), leupeptin, benzamidine, N-p-tosyl-1-lysin-chloromethyl ketone (TLCK) and phenylmethylsulphonyl fluoride (PMSF) and one non-acrosin inhibitor (N-p-tosyl-1-phenylalanine chloromethyl ketone (TPCK) were tested at non-toxic levels (below motility-disturbing concentrations). These inhibitors were added at three different times: (1) during the acrosome reaction of spermatozoa, (2) during sperm-oocyte contact and fusion, and (3) soon after sperm-oocyte fusion was completed. TLCK prevented sperm-oocyte fusion by inhibiting the acrosome reaction. PMSF inhibited gamete fusion, without inhibiting the acrosome reaction. SBTI, leupeptin and benzamidine also inhibited gamete fusion, but they had no effect if spermatozoa were allowed to acrosome-react in inhibitor-free medium. TPCK was without any inhibitory effects, suggesting that chymotrypsin-like enzymes are not involved in gamete fusion. Although acrosin inhibitors prevented acrosome-reacted spermatozoa from becoming fusion-competent, acrosin (and trypsin) alone could not make the plasma membrane of acrosome-intact spermatozoa fusion-competent. The data suggest that (1) the plasma membrane of the acrosomal region first undergoes dramatic changes immediately before or during the acrosome reaction and (2) acrosin released from the acrosome during the acrosome reaction further alters biophysical and biochemical characteristics of the plasma membrane over the equatorial segment. Such dual changes make the plasma membrane of this specialised region of the spermatozoon competent to fuse with the oolemma. Acrosin may not be the only acrosomal enzyme to participate in these changes.

Acrosin↗
PubMed1993

A genetic system controlling mitochondrial fusion in the slime mould, Physarum polycephalum.

We have identified two distinct mitochondrial phenotypes, namely, Mif+ (mitochondrial fusion) and Mif- (mitochondrial fusion-deficient), and have studied the genetic system that controls mitochondrial fusion in the slime mould, Physarum polycephalum. A mitochondrial plasmid of approximately 16 kbp was identified in all Mif+ plasmodial strains. This plasmid is apparently responsible for promoting mitochondrial fusion, and it is inserted into the mitochondrial DNA (mtDNA) in successive sexual crossing with Mif- strains. This recombinant mtDNA and the unchanged free plasmid spread through the mitochondrial population via the promotion of mitochondrial fusion. The Mif+ strains with the plasmid were further classified as being two types: high frequency and low frequency mitochondrial fusion. Restriction analysis of the mtDNA suggested that the high frequency mitochondrial fusion type was more often heteroplasmic; within each plasmodium, mtDNAs of both parental types were usually present, in addition to the presence of the plasmid. Genetic analysis with the progeny obtained from crossing myxamoebae derived from three different isolates suggested that these progeny carried different alleles at a nuclear locus that controlled the frequency of mitochondrial fusion. These alleles (mitochondrial mating-type alleles, mitA1, 2 and 3) appear to function like the mating type of the myxamoebae; mitochondrial fusion occurs at high frequency with the combination of unlike alleles, but at low frequency with the combination of like alleles.

Alleles↗
PubMed1993

Chronic effects of a cardiac assist device on the bulk and regional mechanics of the failed left ventricle in goats.

Pneumatically driven, diaphragm-type left ventricular assist devices (LVADs) were implanted into 8 goats with profound induced infarction to the left ventricle by using multiple ligations of the left anterior descending (LAD) coronary artery as well as small arteries in the LAD distribution area. Left ventricular diameters, regional myocardial segment lengths, and wall thicknesses were measured by sono-micrometers. After left ventricular function seemed to be recovered, the goats were weaned off the LVADs after a gradual decrease of pump bypass flow over several days. Thereafter, hemodynamic and cardiac parameters were observed for about 1 month more. Three animals recovered successfully owing to the LVAD pumping. Before starting pump-weaning procedures, the bulk mechanical work (BMW) done by the left ventricle during LVAD pumping and under temporary pump-off conditions was 0.08 +/- 0.01 (mean +/- SE) and 0.22 +/- 0.01 W/100 g left ventricular weight (LVW), respectively, while the regional mechanical work done by the normal myocardium (RMWn) was 1.5 +/- 0.4 and 4.3 +/- 0.9 mW/cm3 during pumping and under temporary pump-off conditions, respectively. BMW and RMWn values obtained under pump-on conditions both increased gradually during the weaning process. Even after pump removal, they continued to increase and reached constant values of about 0.3 W/100 g LVW and 10 mW/cm3, respectively, around 2 weeks after pump removal. Although the myocardium in the infarction area did no work for the first several days after surgery, it recovered to do some external work with the aid of LVAD pumping. However, recovery of left ventricular function owed more to compensatory increases in pumping ability of the remaining normal myocardium than to recovery of the damaged myocardium. The LVAD could salvage severely damaged hearts unless the infarction area exceeded 50% of the left ventricular wall.

Animals↗
PubMed1993

Successful surgical management of thoracic aortic aneurysm in a right-sided aortic arch.

A 24-year-old woman with a multilocular sacciform aneurysm in a right-sided aortic arch was successfully treated by aneurysmorrhaphy. Although the cause of the aneurysm could be attributed to congenital factors, its growth was considered to be related to the features of the right-sided aortic arch; strong haemodynamic forces were caused by sharp curving of the aorta which started from an unusually high position and subsequently had a decreased radius.

Adult↗
PubMed1993

Deletion mapping of chromosome 3p in human uterine cervical cancer.

Deletion mapping of chromosome 3p was performed on 47 cases of human uterine cervical cancer using 24 polymorphic DNA markers including five inter-Alu DNA markers and two NotI-boundary cosmid markers obtained in our laboratory. The most likely order of these 24 polymorphic DNA markers was determined as being cen-[D3S4, H8]-D3S693-D3S659-D3S30-D3S687-[D3S2, UR9, UR47]-J36-J17-GNAI2B-D3F15S2-D3S643- D3S32-D3S23-D3S686-H35-UR189-D3S685-D3S 11 - D3S12-THRB-D3S22-pter, based on the data from radiation hybrid mapping genetic linkage analysis and in situ hybridization. Loss of heterozygosity (LOH) at one or more loci on chromosome 3p was detected in 21 of 47 cases (45%). Four tumors showed partial or interstitial deletions, and the common region of LOH in these tumors was 3p13-p21.1 between the D3S30 marker and the D3S2 marker. Candidates for tumor-suppressor genes, APEH, D8, GNA12B, ZNF35, RARB, THRB and RAFI, were all mapped outside of the common region in uterine cervical cancer. However, this region is commonly deleted in carcinoma of the lung, breast and kidney, and encompasses the breakpoint of the (3;8) translocation in hereditary renal cell carcinoma. This result indicates the presence of a novel tumor-suppressor gene in the region of 3p13-p21.1, which is involved in the development of several human cancers.

Base Sequence↗
PubMed1993

[Markedly decreased cardiac uptake with 123I-MIBG scintigraphy in a case of pure progressive autonomic failure].

A 70-year-old man with about 25 years' history of autonomic nervous system disturbances including orthostatic hypotension is presented. He had had no extrapyramidal and cerebellar signs, and was diagnosed as having pure progressive autonomic failure. His cardiac imaging with 123I labeled MIBG (metaiodobenzylguanidine) showed extremely diminished uptake, but the imaging with 201-thallium showed a normal cardiac uptake. Those results indicate non-cardiac disease-associated (neurogenic) postganglionic sympathetic fiber abnormality innervating the heart. Also, adrenomedullary imaging with 123I labeled MIBG showed no adrenal image, which suggests the possibility that there should be dysfunction in the adrenal medulla of this patient. This imaging study is thought to be useful for evaluating autonomic nervous system function in neurologic diseases.

3-Iodobenzylguanidine↗
PubMed1993

[Experimental study on heparin-free cardiopulmonary bypass using nafamostat mesilate (FUT-175) and heparin-coated circuit].

We investigated whether the combination of a new synthetic protease inhibitor, nafamostat mesilate (FUT-175), and heparin-coated cardiopulmonary bypass (CPB) circuit can achieve heparin-free CPB in rabbits. Nine rabbits underwent 2 hours of CPB with heparin-coated circuits. In 4 rabbits (FUT-Group), FUT was administered before (2 mg/kg in bolus) and during (5 mg/kg/hr continuously) CPB. In 5 rabbits (Heparin-Group), heparin was given before (4 mg/kg) and at 1 hour (2 mg/kg) of CPB. Activated clotting time, activated partial thromboplastin time and fibrin degradation products showed no significant differences between the two groups during CPB. However, prothrombin time was significantly (p < 0.05) shorter in FUT-Group than in Heparin-Group. Platelet counts in FUT-Group was significantly lower than Heparin-Group. Massive clots were observed in all of the venous reservoirs of FUT-Group after CPB, whereas there were no major clots in Heparin-Group. The occlusion rate of hollow fibers of the oxygenators was significantly higher in FUT-Group (55 +/- 25%, mean +/- SD) than in Heparin-Group (14 +/- 12%). We concluded that heparin-free CPB with FUT and heparin-coated circuit is difficult in rabbits because activation of the extrinsic coagulation cascade cannot be sufficiently suppressed by FUT.

Animals↗
PubMed1993

Clinical application of phosphoenolpyruvate (PEP) to autologous transfusion of patients with open heart surgery.

Patients undergoing surgery for cardiac valve replacement were autologously transfused after their cryopreserved blood was treated with phosphoenolpyruvate. Five patients received red cells treated on the day of operation with a solution containing phosphoenolpyruvate, the other 6 serving as a control group. None of the patients received homologous blood. The treated red cells had a normal adenosine triphosphate concentration; in the control group a 10% decrease was noted. The 2,3-bisphosphoglycerate concentration was 211% of normal in red cells of the treated group and 69% of normal in the control group. The P50 values (mmHg) were 31.1 +/- 3.5 (treated), 20.3 +/- 1.7 (untreated), and 26.1 +/- 0.6 (fresh, not cryopreserved), respectively. Both the 2,3-bisphosphoglycerate and P50 values of the circulating blood were significantly (p < 0.02) increased in the patients receiving treated red cells. The increase in the 2,3-bisphosphoglycerate and P50 remained for 6 hours after transfusion at which time the levels of the 2,3-bisphosphoglycerate were 14.5 +/- 2.2 mumol/gHb (treated group) and 10.5 +/- 0.8 mumol/gHb (control group). Those of P50 were 28.1 +/- 1.5 mmHg (treated group) and 25.9 +/- 0.9 mmHg (control group). The adenosine triphosphate levels were not significantly different. The postoperative values of pH and hematocrit did not differ between the two groups. It was estimated that the oxygen delivery capacity in the circulating blood was about 30% higher in the patients receiving phosphoenolpyruvate treated blood than in those receiving untreated blood.

Adult↗
PubMed1993

[Total arch replacement for dissecting aneurysm using permanent bypass to the supra-aortic branches and left-heart bypass].

The patient was a 36-year-old women with Marfan syndrome who had received graft replacement of ascending aorta for Stanford-type A dissecting aneurysm two years ago. She was re-operated on for residual arch and descending aortic dissection. We have found that it was Simple and effective to perform total arch replacement by using permanent bypass to the three principal supra-aortic branches and left-heart bypass.

Adult↗
PubMed1992

Different sensitivities of human esophageal cancer cells to multiple anti-cancer agents and related mechanisms.

Mechanisms responsible for drug resistance in human esophageal cancer cell lines were investigated. Three cell lines established from human esophageal carcinoma (TE-1, SH-1, and TH) showed different sensitivities to vindesine, vincristine, cisplatin (CDDP), etoposide (VP-16), and pepleomycin. Both SH-1 and TH cell lines were twofold to sevenfold more resistant to pepleomycin, vindesine, and vincristine than TE-1 was. SH-1 showed twofold more resistance to CDDP than either TE-1 or TH did, and TH and TE-1 showed a 3-fold or 1.5-fold more resistance, respectively, to VP-16 than SH-1 did. The accumulation of tritiated vincristine in SH-1 and TH was approximately 50% that in TE-1. Two multidrug resistance reversal agents, cepharanthine and a synthetic dihydropyridine analogue (NK-252; Nikken Chemicals, Saitama, Japan), potentiated the cytocidal actions of vindesine against SH-1, TH, and TE-1 cells, with no apparent expression of P-glycoprotein in the three cell lines. The glutathione S-transferase pi gene was expressed in all three cell lines. DNA topoisomerase II levels were lowest in TE-1, followed by SH-1 and TH, although the accumulation of tritiated VP-16 was less in both TH and SH-1 than in TE-1. Differential sensitivities to anti-cancer drugs appear to be mediated through pleiotropic mechanisms.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1992

Serial assessment of denervated but viable myocardium following acute myocardial infarction in dogs using iodine-123 metaiodobenzylguanidine and thallium-201 chloride myocardial single photon emission tomography.

Iodine-123 metaiodobenzylguanidine (mIBG) is taken up by sympathetic nerve endings, allowing scintigraphic imaging of myocardial sympathetic innervation. We investigated the denervated but viable canine myocardium after acute myocardial infarction by serial mIBG and thallium-201 chloride (201TlCl) single photon emission tomography (SPET). In 12 dogs, acute myocardial infarction was produced by ligation of the left circumflex coronary artery. Images of mIBG and thallium SPET were obtained 6 h, 1, 4 and 6 weeks later. The defect size was calculated in percentage points from short axial views, and the 123I-mIBG/201TlCl ratio was determined. The uptake ratio was high at 1 week but gradually decreased. Three dogs were killed at each time point, and tissue samples were obtained from infarcted (both 201TlCl and 123I-mIBG defects), peri-infarcted (123I-mIBG defect and 201TlCl normal) and normal myocardium (both mIBG and 201TlCl normal). The changes in tissue content of noradrenaline in these lesions were measured. Noradrenaline tissue content gradually recovered in the peri-infarcted area. However, no recovery was noted in the infarcted area at 6 weeks. We conclude that sympathetic denervation and re-innervation occur following acute myocardial infarction, and the denervated but viable myocardium could be detected non-invasively by combined mIBG and thallium SPET.

3-Iodobenzylguanidine↗
PubMed1992

Constitutive homologous recombination between mitochondrial DNA and a linear mitochondrial plasmid in Physarum polycephalum.

In one particular myxamoebal strain (NG7; mF+) of Physarum polycephalum, a linear mitochondrial plasmid (mF plasmid) which promotes mitochondrial fusion has been identified. A mating between mF- strains, that do not carry the mF plasmid, resulted in uniparental inheritance of the mtDNA. In matings between mF+ and mF- strains a recombination occurred between the mtDNA and the mF plasmid, and recombinant mtDNA was generated with the end of the mF plasmid as its ends. The DNA sequences of the recombination site in the mtDNA and the mF plasmid, and of the recombinant mtDNA, revealed that the mF plasmid had a 473-bp sequence that was identical to, but slightly shorter than, a 477-bp sequence of the mtDNA. This so-called identical sequence was found at the junction between unique sequences of the mF plasmid and the mtDNA in the recombinant mtDNA. Thus, the recombination between the mtDNA and the mF plasmid was due to reciprocal crossing-over at the identical sequence.

Animals↗
PubMed1992

Augmentative effects of tumor necrosis factor-alpha (human, natural type) on polymorphonuclear leukocyte-derived superoxide generation induced by various stimulants.

We investigated the effects of tumor necrosis factor-alpha (human, natural type: n-TNF) on polymorphonuclear leukocyte (PMN)-derived superoxide generation by the new method of Cypridina luciferin analog-dependent chemiluminescence, which had high sensitivity and specificity to superoxide. Preincubation of PMNs with n-TNF for 3 min increased PMN-derived superoxide generation induced by phorbol myristate acetate, A23187, opsonized zymosan and N-formyl-methionyl-leucyl-phenylalanine in a concentration dependent manner (0.5-50 Japan reference units/ml of n-TNF). In addition, the enhanced PMN-derived superoxide generation by n-TNF showed a positive correlation to the preincubation time of PMNs with n-TNF (3-15 min). However, a direct incubation of PMNs with n-TNF for 1 h did not induce superoxide from PMNs without the above stimulants. The augmentative effects of n-TNF on PMN-derived superoxide generation should be useful in the PMN-mediated host defense mechanism, such as bactericidal and antitumor activity. The local concentration of n-TNF and the n-TNF-PMN contact time are considered very important in obtaining these effects more efficiently in addition to the presence of PMN-stimulants including complements, chemotactic peptides and phorbol esters.

Dose-Response Relationship, Drug↗
PubMed1992

DNA topoisomerase-targeting antitumor agents and drug resistance.

A review of the chemotherapeutic agents which have been developed by targeting DNA topoisomerase I and II is presented. Camptothecins as topoisomerase I-targeting agents and newly developed topoisomerase II-targeting agents with unique properties are expected to be promising anticancer agents in the near future. An important issue is how cellular sensitivity to these agents is controlled. One approach is to establish and characterize drug-resistant human cancer cell lines, which would provide powerful tools to understand their intracellular target sites and also the mechanisms for acquirement of drug resistance to topoisomerase inhibitors. Drug resistance to topoisomerase-targeting agents appears to be closely correlated with two events, namely decreased expression and point mutation of topoisomerase genes.

Antineoplastic Agents↗