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Biomedical subjects

H Sakurai

Publications and source records attributed to H Sakurai.

At least 199 records · Page 11Linked to original sources

A new insulin-mimetic vanadyl complex, (N-pyridylmethylaspartate)oxovanadium(IV) with VO(N2O2) coordination mode, and evaluation of its effect on uptake of D-glucose by Ehrlich ascites tumour cells.

Because it has been confirmed that the vanadyl(IV) ion and its complexes act as insulin mimetics, a new organic vanadyl complex, (N-pyridylmethylaspartate)oxovanadium (VOPASP) with VO(N2O2) coordination mode, was prepared. Development of a simple and rapid in-vitro assay is needed for recognition of potent insulin-mimetic complexes. Treatment of Ehrlich ascites tumour cells with 2-deoxyglucose in the presence of vanadyl sulphate, or other vanadyl complexes with the same coordination mode (VOPASP, bis(picolinate)oxovanadium (VOPA) and bis(6-methyl picolinate)oxovanadium (VOMPA)), in the presence of 2-deoxy-D-[1-3H]glucose ([3H]deoxyglucose), resulted in concentration-dependent uptake of 2-deoxyglucose by the cells. The responses of the cells to the vanadyl complexes were reflected, in part, by results obtained from the free fatty acid-releasing assay using rat adipocytes. These results show that the in-vitro assay with Ehrlich ascites tumour cells provides an accurate and rapid assessment of glucose uptake by the cells. The assay is proposed as a means of predicting the insulin-mimetic activity of the vanadyl complexes and for studying the mechanism of action of the complexes.

Animals↗

Unique expression patterns of myosin heavy chain genes in the ductus arteriosus and uterus of rabbits.

In smooth muscle tissue, two smooth muscle myosin heavy chain (MHC) isoforms (SM1, SM2) and two non-muscle MHC isoforms (NMA, NMB) have been identified. The purpose of our study was to clarify whether smooth muscle MHC mRNA expression reflects the physiological and functional state of the muscle. We studied the expression pattern of MHC mRNAs, using the S1-nuclease mapping procedure, in functionally and morphologically changeable organs; the ductus arteriosus (DA) during development (25 and 29 days of gestation, and from 3-day-old neonates) and uteri from virgin, day-10 pregnant (P10) and day-29 pregnant (P29) rabbits. The results demonstrated that SM2 expression was greater in the fetal DA than in the fetal aortic and pulmonary arteries, but that it decreased significantly following closure of DA. In the gravid uterus, SM1 expression was significantly (P<0.05) strong compared to other MHC mRNAs from virgin to P10 rabbits. During pregnancy, NMB expression showed a tendency to increase until P10, and after P10, SM2 expression increased dramatically and NMB expression decreased to give almost a mirror image of the SM2 expression. Smooth muscle type (SM1, SM2) was significantly (P<0.05) strong compared to non-muscle type expression (NMA, NMB) at P29. These data suggest that smooth muscle MHC mRNA, especially SM2 expression reflects the physiological and functional state of the smooth muscle.

Animals↗

Effect of stress-like concentrations of cortisol on follicular development and the preovulatory surge of LH in sheep.

Stress-like concentrations of cortisol increase the negative feedback potency of oestradiol in castrated male sheep. A similar cortisol-dependent response in female sheep might be expected to suppress gonadotrophin secretion and impair follicular development and ovulation. The oestrous activity of 21 female sheep was synchronized using progestogen-treated vaginal pessaries to test this hypothesis. Stress-like concentrations of cortisol (60-70 ng ml-1) were established by continuous infusion of cortisol (80 micrograms kg-1 h-1; n = 13) beginning 5 days before, and continuing for 5 days after, pessary removal. Control animals (n = 8) received a comparable volume of vehicle (50% ethanol-saline) over the 10 day infusion period. Serum concentrations of oestradiol increased progressively in control sheep during the 48 h immediately after pessary removal. This increase in serum oestradiol was blocked or significantly attenuated in sheep receiving stress-like concentrations of cortisol. Preovulatory surge-like secretion of LH was apparent in control animals 58.5 +/- 2.1 h after pessary removal. In contrast, surge-like secretion of LH was not observed during the 5 days after pessary removal in 54% (7 of 13) of sheep receiving cortisol. Moreover, the onset of the surge was significantly delayed in the cortisol-treated ewes that showed surge-like secretion of LH during the infusion period. The ability of episodic pulses of exogenous GnRH to override the anti-gonadal effect of cortisol was examined in a second study. Oestrous activity of 12 ewes was synchronized using progestogen-containing pessaries as described above. Ewes were randomly assigned to one of three treatment groups (n = 4 ewes per group). Animals received cortisol (100 micrograms kg-1 h-1; groups 1 and 2) or a comparable volume of vehicle (group 3) beginning 5 days before, and continuing for 2 days after, pessary removal. Pulses of GnRH (4 ng kg-1 h-1, i.v.; group 1) or saline (groups 2 and 3) at 1 h intervals were initiated at pessary removal and continued for 48 h. Serum concentrations of oestradiol were not significantly increased after pessary removal in sheep receiving cortisol alone. Conversely, serum concentrations of oestradiol increased progressively during the 48 h after pessary removal in control ewes and in ewes receiving cortisol and GnRH. At the end of infusion, serum concentrations of oestradiol did not differ (P > 0.05) between control (7.7 +/- 0.8 pg ml-1) ewes and ewes receiving cortisol and episodic GnRH (6.4 +/- 1.3 pg ml-1). Moreover, these values were significantly greater (P < 0.05) than the serum concentrations of oestradiol in animals receiving cortisol (1.0 +/- 0.4 pg ml-1) alone. Collectively, these data indicate stress-like concentrations of cortisol block or delay follicular development and the preovulatory surge of LH in sheep. In addition, episodic GnRH overrides cortisol-induced delay in follicular maturation.

Analysis of Variance↗

Successful treatment of immunoblastic lymphadenopathy-like T-cell lymphoma with cyclosporin A.

Immunoblastic lymphadenopathy (IBL)-like T-cell lymphoma is considered to belong to peripheral T-cell lymphoma. Its prognosis is grave and effective treatments have not been established. Recently, we gave oral cyclosporin A (CsA) to a patient with IBL-like T-cell lymphoma, and succeeded in achieving dramatic remission. In this case, serum levels of interleukin-12 (IL-12) and tumor necrosis factor-alpha (TNF alpha) were elevated and decreased or returned to normal after achieving remission. Since CsA is a potent suppressor of the immune system and most notably T-cells, the immunosuppression of T-cell function might have played an important role in achieving remission in this case, although the precise mechanism still remains to be elucidated. The present case indicates that administration of CsA may be a very effective and safe selection of therapy for IBL-like T-cell lymphoma, as well as analogous disorders such as IBL and angioimmunoblastic lymphadenopathy with dysproteinemia (AILD), thereby will contribute to improving the prognosis of patients with these diseases.

Administration, Oral↗

Extended use of hemofiltration and high perfusion flow rate in cardiopulmonary bypass improves perioperative fluid balance in neonates and infants.

We evaluated the efficacy of the extended use of hemofiltration (EHF) and high perfusion flow rate in cardiopulmonary bypass (CPB) in pediatric open-heart surgery retrospectively. In the EHF method, hemofiltration was used for hemic prime before initiation of the bypass and ultrafiltration was used throughout the bypass. Thirty-four children, with transposition of great arteries who were undergoing arterial switch operation with the use of hemic prime, were subjects of this study. They were divided into 2 groups, a control group (n = 16) and a group (n = 18) that underwent EHF. There were no significant differences between groups in demographics, but the maximum perfusion index and lowest rectal temperature were higher in the EHF group. This study compared urination during bypass, arterial oxygen pressure at the end of bypass and operation, the duration of the ventilation, and postoperative soft tissue index (STI) expressing the severity of edema. In the EHF group, urination during bypass was significantly higher, and there was a tendency to higher arterial oxygen pressure. The patients in the EHF group were weaned from the ventilator significantly earlier. Postoperative STI was significantly higher, so edema was more severe in the control group. We consider that the use of EHF and a high perfusion flow rate in CPB are an ideal method to improve the perioperative fluid balance in pediatric open-heart surgery. We suspect that these good clinical effects result from maintaining the inflammatory mediators at a low level throughout the bypass, reducing the following release of the mediators and attenuating the interaction of the mediators.

Blood Flow Velocity↗

[Experience with repair of muscular trabecular ventricular septal defects].

We reviewed the records of 9 pediatric patients with muscular trabecular ventricular septal defects undergoing repair between April 1994 and June 1998 (mean age 2.6 +/- 3.1 years, mean weight 9.0 +/- 5.2 kg). The prevalence rate for muscular trabecular defects in the patients undergoing open-heart surgery for congenital heart disease was 2.0%. Although only 6 of the 9 patients were diagnosed as having muscular trabecular defects preoperatively, 60 degrees left anterior oblique and 30 cranially tilted projections of left ventricular cineangiocardiogram were useful to detect these defects. The technique of filling the left heart with blood by stopping to vent the left heart and inflating the lungs during the last one or two ligatures in closure of the defects was also useful to detect these defects intraoperatively. In closure of muscular trabecular defects, division of some trabeculations including a moderator band enabled complete repair through a right atriotomy. The nearer the inferior border of the ventricular septal defects were to the heart apex, the more postoperative residual shunts were left. We consider that apical left ventriculotomy may be needed in apical defects, although the right atrial approach is satisfactory for most muscular trabecular defects.

Child↗

Apoptosis and appearance of Trp53-positive micronuclei in murine tumors with different radioresponses in vivo.

The purpose of this paper is to determine the relationship between the response to radiation and the appearance of apoptosis and micronuclei with Trp53 protein in murine tumors after irradiation. Two murine tumors, EL4, which was derived from a mouse lymphoma, and FM3A, which was derived from a mouse mammary carcinoma, were locally irradiated with 15 Gy and sections were stained with H&E and an anti-Trp53 antibody. The response to radiation was greater in EL4 tumors than in FM3A tumors. The frequency of apoptotic cells in EL4 tumors was 6.1 +/- 1.2% at time zero, reached a peak of 36.3 +/- 3. 8% at 6 h, and then decreased with time through 72 h to 2.5 +/- 1.5% after 15 Gy irradiation. In FM3A tumors, no apoptotic cells were detected at 0, 1, 3, 6 or 24 h after exposure. At 48 and 72 h, the frequency was only 3.0 +/- 0.6% and 1.3 +/- 0.3%. Apoptotic cells increased significantly at 3, 6 and 24 h after irradiation in EL4 tumors (P < 0.008) and at 48 and 72 h in FM3A tumors (P < 0.006). The frequency of Trp53-positive cells was 17.9 +/- 2.2 and 15.2 +/- 2.3% at time zero in EL4 and FM3A tumors, respectively, increased to 74.5 +/- 4.5% in EL4 cells (P = 0.001), and increased to 33.9 +/- 1. 1% in FM3A cells (P = 0.005) 1 h after irradiation. Trp53-positive micronuclei appeared in cells in both tumors from 24 to 72 h after irradiation. The frequency of Trp53-positive micronuclei was 3.8 +/- 0.5 and 13.5 +/- 1.3% at 24 h in EL4 and FM3A tumors, respectively, and gradually decreased by 72 h. After exposure to 15 Gy, Trp53-positive micronuclei increased significantly in FM3A tumors compared to EL4 tumors at both 24 and 48 h (P < 0.02). The frequency of these micronuclei increased with increasing dose in FM3A tumors, and the difference between these percentages after 3 Gy and after 5, 10 and 15 Gy was significant (P < 0.02). Many apoptotic cells were observed in the radiosensitive EL4 tumor after irradiation. Death by apoptosis may be related to an early response to radiation in these tumors. The appearance of micronuclei may be an important mechanism of cell death in FM3A tumors in which no apoptosis was induced.

Animals↗

Giant cell tumor of the thoracic spine simulating mediastinal neoplasm.

A case of giant cell tumor of the thoracic spine simulating mediastinal neoplasm was identified on plain films, CT scans, MR images, and with scintigraphy. CT showed a hypervascular soft-tissue mass with shell-like calcification in the right upper mediastinum. MR imaging showed a collapse of the T1 vertebral body and a mass extending to the mediastinum. The mass had a low signal on T1-weighted MR images and a predominantly high signal on T2-weighted images with heterogeneity. Technetium-99m methylene diphosphonate bone scintigraphy showed intense uptake in both the T1 and marginal parts of the mediastinal mass. There was no accumulation of gallium-67 citrate, but 18-fluorine fluorodeoxyglucose positron emission tomography showed marked uptake. The variation in these imaging findings played an important role in the differential diagnosis of this uncommon mediastinal mass.

Adult↗

Identification of the gene and the protein of RNA polymerase II subunit 9 (Rpb9) from the fission yeast Schizosacharomyces pombe.

Both the rpb9 gene and its cDNA encoding the subunit 9 of RNA polymerase II were cloned from the fission yeast Schizosaccharomyces pombe. From the DNA sequences, Rpb9 was predicted to consist of 113 amino acid residues with a molecular mass of 13,175. S. pombe Rpb9 is 47, 40 and 36% identical in amino acid sequence to the corresponding subunits from Saccharomyces cerevisiae, human and Drosophila melanogaster, respectively. Previously, we failed to detect Rpb9 in the purified RNA polymerase II by amino-terminal micro-sequencing of proteolytic fragments of subunits separated by SDS-gel electrophoresis. After Western blot analysis using antibodies raised against the protein product of the newly isolated rpb9 gene, we found that the purified RNA polymerase II contains Rpb9.

Amino Acid Sequence↗

HTHQ (1-O-hexyl-2,3,5-trimethylhydroquinone), an anti-lipid-peroxidative compound: its chemical and biochemical characterizations.

Recently, it has become apparent that reactive oxygen species (ROS) play many important roles in biological systems. For example, relationships between many diseases, such as cancer, cardiac infarction and arteriosclerosis, and ROS have been found. It is also well known that anti-oxidative agents scavenge ROS in biological systems, which in turn prevents ROS-related diseases. In our previous efforts to develop effective anti-oxidative compounds, we found that 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), which is a hydroquinone monoalkyl ether, is a potent anti-oxidative agent. Here, the scavenging activities of HTHQ against ROS, such as superoxide anion radicals, hydroxyl radicals, t-butyl peroxyl radicals and singlet oxygens, were examined by the ESR (electron spin resonance)-spin trapping method. Among ROS, HTHQ scavenged t-butyl peroxyl radicals most effectively (IC50=0.31+/-0.04 mM), showing approximately twice the activity of a well-known lipophilic anti-oxidant, D,L-alpha-tocopherol (IC50=0.67+/-0.06 mM), as measured by IC50 values defined as the 50% inhibition concentration of the generated ROS. In addition, a relatively stable ESR spectrum of free radicals due to HTHQ was observed during the reaction of HTHQ and t-butyl peroxyl radicals, indicating a direct reaction of HTHQ and t-butyl peroxyl radicals. The free radicals due to HTHQ were more stable than those derived from D,L-alpha-tocopherol under the same conditions examined. On the basis of these results, we evaluated anti-lipid-peroxidative activity of HTHQ in three systems involving micelles, liposomes and rat liver microsomes. HTHQ exhibited a similar anti-oxidative activity to that of D,L-alpha-tocopherol against lipid peroxidation in linolate micelles initiated by addition of Fe2+. On the other hand, HTHQ exhibited approximately 4.8-fold higher anti-lipid-peroxidation activity than that of D,L-alpha-tocopherol against the peroxidation in phosphatidylcholine liposomes initiated by addition of Fe2+. Furthermore, HTHQ scavenged the lipid peroxides at a rate approximately 150 times higher than that of D,L-alpha-tocopherol against Fe3+ -ADP-induced lipid peroxidation in rat liver microsomes, indicating that the anti-lipid-peroxidation activity of HTHQ might be substantially elevated in biological systems in comparison with that of D,L-alpha-tocopherol. Based on these results, we suggest that HTHQ reacts directly with peroxyl radicals, such as t-butyl peroxyl radicals and peroxides of linolate micelles, liposomes and microsomes, by scavenging them to form stable free radicals. The resulting free radicals are presumed to be reduced by several reducing mechanisms in biological systems similarly to those of D,L-alpha-tocopherol, and then the lipid-peroxidation reactions will be terminated. In conclusion, HTHQ was found to be a potent anti-lipid-peroxidative compound and its antioxidation activity to be extremely elevated in biological systems, such as that of liver microsomes via the generation of stable free radicals. We propose that HTHQ is a potent anti-oxidative agent for use in future treatments for lipid-peroxide relevant diseases.

Animals↗

Early radiation effects in highly apoptotic murine lymphoma xenografts monitored by 31P magnetic resonance spectroscopy.

PURPOSE: Phosphorus-31 magnetic resonance spectra (31P-MRS) were obtained from highly apoptotic murine lymphoma xenografts before and up to 24 hr following graded doses of radiation ranging from 2 to 30 Gy. Radiation-induced apoptosis was also estimated up to 24 hr by scoring apoptotic cells in tumor tissue. METHODS AND MATERIALS: Highly apoptotic murine lymphoma cells, EL4, were subcutaneously transplanted into C57/BL mice. At 7 days after transplantation, radiation was given to the tumor with a single dose at 3, 10, and 30 Gy. The beta-ATP/Pi, PME/Pi, and beta-ATP/PME values were calculated from the peak area of each spectrum. Radiation-induced apoptosis was scored with counting apoptotic cells on hematoxylin and eosin stained specimens (% apoptosis). RESULTS: The values of % apoptosis 4, 8, and 24 hr after radiation were 21.8, 19.6, and 4.6% at 3 Gy, 35.1, 25.6, and 14.8% at 10 Gy, 38.4, 38.0, and 30.6% at 30 Gy, respectively (cf. 4.4% in control). There was no correlation between early change in beta-ATP/Pi and % apoptosis at 4 hr after radiation when most of the apoptosis occurred. An early decrease in PME/Pi was observed at 4 hr after radiation dose at 30 Gy. For each dose, the values of beta-ATP/Pi 24 hr after radiation were inversely related to radiation dose. CONCLUSION: The increase in beta-ATP/Pi observed by 31P-MRS was linked to the degree of histological recovery from radiation-induced apoptosis.

Adenosine Triphosphate↗

Development of an (X, eX) spectrometer for measuring the energies of the scattered photon and recoil electron.

The design and performance of a new spectrometer for coincidence measurements between the Compton scattered photon and the recoil electron are described. Coincidence measurements give direct information on the three-dimensional electron momentum density (EMD) of condensed matter. The present spectrometer measures energy spectra of both the photon and the electron. The energy spectrum of electrons is measured by a time-of-flight method using single-bunch operation at the Photon Factory Accumulator Ring (PF-AR). The energy resolution obtained for the recoil electron is 190 eV, which is better than that of the photon detector, so that a momentum resolution of the three-dimensional EMD of 0.3 atomic units can be achieved.

Journal Article↗

High-pressure system for Compton scattering experiments.

High-pressure apparatus for Compton scattering experiments has been developed to study the momentum distribution of conduction electrons in metals and alloys at high pressure. This apparatus was applied to observe the Compton profile of metallic Li under pressure. It was found that the Compton profile at high pressure could be obtained within several hours by using this apparatus and synchrotron radiation. The result on the pressure dependence of the Fermi momentum of Li obtained here is in good agreement with that predicted from the free-electron model.

Journal Article↗

Radiotherapeutic Management of Brain Metastases from Breast Cancer.

We have reviewed the medical records of 28 breast cancer patients with brainmetastases who were treated with radiotherapy at our clinic from 1980 through 1994(4 patients, postoperatively; 24 patients, radiotherapy alone). Radiotherapy was delivered as whole brain irradiation using lateral opposed 10 MV X-rays. Tenpatients received an additional boost to a reduced field. One patient was treated with localized stereotactic irradiation alone. The radiation dose for tumorsranged from 32 Gy to 60 Gy(mean, 49 Gy)in 2 or 3 Gy daily fractionated doses. The brain was the first site of metastatic involvement in only two patients. In the 26 evaluable patients, neurologic functional improvement was achieved in 24 patients(92%)with complete response(CR)in 12 patients(46%)and partial response(PR)in 12 patients(46%). The survival rates from the initial treatment were 39% at 5 years and 16% at 10 years(median survival time, 50 months), and those after treatment of brain metastases were 29% at one year and 18% at 2 years(median survival time, 6 months). Performance status tended to be associated with survival(p=0.10), and the presence of liver metastasis was the most important risk factor concerning survival(p=0.056). Two patients suffered severe chronic complications.One patient developed severe dementia after whole brain irradiation with a total dose of 45 Gy in 3 Gy daily fractionated dose, and another patient developed widespread brain necrosis after combined radiotherapy with intrathecal local infusion of methotrexate. Radiotherapeutic management is useful for breast cancer patients with brain metastasis, and long-term survival may also be possible even if patients have preexisting extracranial metastases, except for hepatic involvement. Radiation-related complications should therefore be avoided in these patients.

Journal Article↗

Functional correlation among Gal11, transcription factor (TF) IIE, and TFIIH in Saccharomyces cerevisiae. Gal11 and TFIIE cooperatively enhance TFIIH-mediated phosphorylation of RNA polymerase II carboxyl-terminal domain sequences.

Saccharomyces cerevisiae Gal11, a component of the holoenzyme of RNA polymerase II, interacts through its functional domains A and B with the small (Tfa2) and large (Tfa1) subunits of the general transcription factor (TF) IIE, respectively. We have recently suggested that Gal11 functions through a common pathway with TFIIE in transcriptional regulation (Sakurai, H., and Fukasawa, T. (1997) J. Biol. Chem. 272, 32663-32669). Here, we report that the activity of the TFIIH-associated kinase, responsible for phosphorylation of the largest subunit of RNA polymerase II at the carboxyl-terminal domain (CTD), is enhanced cooperatively by Gal11 and TFIIE. The enhancement of CTD phosphorylation was observed in the holoenzyme of RNA polymerase II, but not in its core enzyme. The stimulatory effect was completely abolished in the absence of either domain B of Gal11 or the Tfa1 subunit of TFIIE, suggesting that the domain B-Tfa1 interaction is necessary, if not sufficient, for an extensive phosphorylation of the CTD by TFIIH. Stimulation of basal transcription by Gal11 was coupled with enhancement of TFIIH-catalyzed CTD phosphorylation in a cell-free transcription system, suggesting that Gal11 activates transcription by stimulating the CTD phosphorylation in the cell.

Cell Nucleus↗

Generation of nitric oxide from streptozotocin (STZ) in the presence of copper(II) plus ascorbate: implication for the development of STZ-induced diabetes.

Streptozotocin (STZ) is widely used as a strong inducer of insulin-dependent diabetes in experimental animals. Although nitric oxide (NO) generation from STZ has been proposed to be responsible for the toxicity of pancreatic B-cells, the mechanism is yet unknown. We found that STZ generates NO in the presence of Cu(II) plus ascorbate. In addition, nicotinamide, which is an antidiabetic agent against STZ, has been found to inhibit NO generation from STZ during the reaction with Cu(II) plus ascorbate. Since rat pancreatic islets contain both ascorbate and Cu at the concentrations of 3.5 mM and 1. 0 nmol/mg protein, respectively, our present results indicate that (1>) NO generation is responsible for the development of STZ-induced diabetes and (2) mechanism for the protection of diabetes by nicotinamide is due to the inhibition of NO generation from STZ through complex formation between nicotinamide and Cu (I), which is reduced by ascorbate.

Animals↗

Diffusion-weighted MR imaging of the hippocampus and temporal white matter in Alzheimer's disease.

We investigated the changes in water diffusion in the hippocampus and the temporal white matter (the temporal stem) in eight patients with possible Alzheimer's disease (AD), 10 patients with probable AD, and 10 age-matched controls, using coronal diffusion-weighted magnetic resonance (MR) imaging. Apparent diffusion coefficients (ADCs) were derived for the three orthogonal axes and an index of diffusion anisotropy (IDA = ADC(max-min)/ADC(mean)) was then calculated. Although no significant differences were found in ADC and IDA values in the hippocampal body between controls and patients, vertical (superior-inferior) ADC values and ADC(mean) values in the temporal stem of patients with AD were significantly higher than those in controls, and IDA values were therefore significantly lower in patients with possible or probable AD than those in controls. Moreover, IDA values in the temporal stem were significantly correlated with the clinical severity. These results suggest that decreased fiber density, such as the disruption and loss of axonal membranes or myelin, occur early in the temporal stem, probably due to secondary degeneration related to grey matter pathology including the medial temporal lobe.

Aged↗