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Biomedical subjects

Y Tanimura

Publications and source records attributed to Y Tanimura.

At least 19 recordsLinked to original sources
PubMed2006

Contribution of systemic arterial compliance and systemic vascular resistance to effective arterial elastance changes during exercise in humans.

BACKGROUND: Effective arterial elastance (Ea), an index of arterial load, increases with elevations in left ventricular elastance to maximize the efficiency of left ventricular stroke work during exercise. Systemic arterial compliance (C) and vascular resistance (R) are the primary components contributing to Ea, and R plays a greater role in determining Ea at rest. We hypothesized that the contribution of C to Ea increases during exercise to maintain an optimal balance between arterial load and ventricular elastance, and that the increase in Ea is due primarily to a reduction in C. AIM: The aim of this study was to investigate the contributions of C and R to Ea during exercise. METHODS: Ea (0.9 x systolic blood pressure/stroke volume), C (stroke volume/pulse pressure), R (mean blood pressure/cardiac output), and cardiac cycle length (T) were measured at rest and during exercise of 40%, 60% and 80% maximal oxygen uptake (O(2max)) using Doppler echocardiography in 45 healthy men. RESULTS: Ea did not differ between rest and 40%O(2max), but it was greater at 60% and 80%O(2max). C markedly decreased during exercise in an exercise intensity-dependent manner. The changes in R/T during exercise were small, whereas it decreased at 40%O(2max) and gradually increased at 60% and 80%O(2max). CONCLUSIONS: The present results suggest that the contribution of systemic arterial compliance to effective arterial elastance increases during exercise. Therefore, we propose that the increase in arterial load during exercise is mainly driven by a reduction in systemic arterial compliance.

Adult↗
PubMed2004

Conceptual design of spectrum changeable neutron calibration fields in JAERI/FRS.

Spectrum changeable neutron calibration fields are planned to be established with an accelerator installed in Japan Atomic Energy Research Institute/Facility of Radiation Standards. The neutron fields are provided by bombarding a target surrounded by a moderator, with charged particles from the accelerator. In the fields, a wide variety of neutron spectra is provided with sufficient fluence rate for the calibration of dosemeters. In this study, necessity of the field was first discussed in view of relationship between readings of existing dosemeters and true dose equivalents where the dosemeters were used. Second, test simulation of neutron spectra was carried out with the Monte Carlo technique for some arrangements with a LiF target and quasi-cylindrical moderators with different materials. The simulated spectra were summarised in terms of fluence-average energy, fluence rate and calibration factor for the dosemeters.

Algorithms↗
PubMed2004

Construction of 144, 565 keV and 5.0 MeV monoenergetic neutron calibration fields at JAERI.

Monoenergetic neutron calibration fields of 144, 565 keV and 5.0 MeV have been developed at the Facility of Radiation Standards of JAERI using a 4 MV Pelletron accelerator. The 7Li(p,n)7Be and 2H(d,n)3He reactions are employed for neutron production. The neutron energy was measured by the time-of-flight method with a liquid scintillation detector and calculated with the MCNP-ANT code. A long counter is employed as a neutron monitor because of the flat response. The monitor is set up where the influence of inscattered neutrons from devices and their supporting materials at a calibration point is as small as possible. The calibration coefficients from the monitor counts to the neutron fluence at a calibration point were obtained from the reference fluence measured with the transfer instrument of the primary standard laboratory (AIST), a 24.13 cm phi Bonner sphere counter. The traceability of the fields to AIST was established through the calibration.

Algorithms↗
PubMed2004

Neutron spectra and angular distributions of concrete-moderated neutron calibration fields at JAERI.

The Facility of Radiation Standards of Japan Atomic Energy Research Institute has been equipped with concrete-moderated neutron calibration fields as simulated workplace neutron fields. The fields use an 241Am-Be neutron source placed in the narrow space surrounded by concrete bricks, walls and floor. The neutron spectra and the neutron fluence rates of the fields were measured with the Bonner multi-sphere spectrometer system (BMS), spherical recoil-proton proportional counters, and a liquid scintillation counter (NE-213). The results were compared with each other. The reference values of H*(10) were determined from the results of BMS. The angular distributions of neutron fluence were calculated using MCNP-4B2 to obtain the reference values of Hp(10). The calculated results show that the scattered neutrons have a wide range of incident angles. The reference Hp(10) values considered the angular distribution were found to be 10-18% smaller than those without consideration.

Algorithms↗
PubMed2000

Heme-copper oxidase family structure of Magnetospirillum magnetotacticum 'cytochrome a1'-like hemoprotein without cytochrome c oxidase activity.

The genes encoding 'cytochrome a1'-like hemoprotein of Magnetospirillum magnetotacticum were identified and sequenced. Three ORFs, mcalI, mcaI and hosA, were included in the sequenced region. The six histidine residues which were predicted to associate with the prosthetic cofactors of heme-copper oxidase superfamily were conserved in the hemoprotein. However, none of the amino acid residues which were proposed to participate in the oxygen-reducing and the coupled proton pumping reactions in cytochrome c oxidase were at all conserved in the hemoprotein.

Amino Acid Sequence↗
PubMed1999

Femtochemistry.

The topic of femtochemistry is surveyed from both theoretical and experimental points of view. A time-dependent wave packet description of the photodissociation of the O---C---S molecule reveals vibrational motion in the transition-state region and suggests targets for direct experimental observation. Theoretical approaches for treating femtosecond chemical phenomena in condensed phases are featured along with prospects for laser-controlled chemical reactions by using tailored ultrashort chirped pulses. An experimental study of the photoisomerization of retinal in the protein bacteriorhodopsin is discussed with an aim to gain insight into the potential energy surfaces on which this remarkably efficient and selective reactions proceeds. Finally, a prospective view of new frontiers in femtochemistry is given.

Bacteriorhodopsins↗
PubMed1995

[Polychlorinated biphenyls (PCBs) and polychlorinated quaterphenyls (PCQs) concentrations in skin surface lipids and blood of patients with Yusho].

The relationship between Polychlorinated Biphenyls (PCBs), and Polychlorinated Quaterphenyls (PCQs) concentrations in the skin surface lipids and blood was investigated in twenty two patients with PCB poisoning (Yusho) and 9 control subjects were analyzed. The collection of skin surface lipids was performed by the method of cotton pad with 70% ethyl alcohol. The alkaline decomposition method described as "the official standard analytical methods for the isolation of PCBs and PCQs fractions" was used. In the blood of control group, the mean value of PCBs concentration was 1.8 ng/g, and that of PCQs concentration was very low and undetectable by our analytical method. On the other hand, the PCBs concentration in the Yusho group was three times higher than those in the control group. The mean value of PCQs concentration was 1.90 ng/g in Yusho group, while it was not detectable in the control group. In the skin surface lipids of patients with Yusho, the mean value of PCBs concentration was 668.6 ng/g, but was 256.7 ng/g in the control group. The mean value of PCQs concentration in the skin surface lipids of Yusho patients was 35.4 ng/g, although it was not detected in the control group. These values of the skin surface lipids in 1993 were decreased as compared with those in 1992. PCBs and PCQs levels in the skin surface lipids were higher than those in the blood. These findings suggests that cutaneous sebaceous system is one of the excretory systems of polyhalogenated chemicals, such as PCBs or PCQs, when these chemicals are precipitated in human or mammalian.

Chlorobenzenes↗
PubMed1990

Serum and urinary N-acetyl-beta-D-glucosaminidase activity among the inhabitants of a rural area in Japan--the effect of age and hypertension.

In this paper, the normal values, distribution, and variations in serum and urinary activities of the lysosomal enzyme, N-acetyl-beta-D-glucosaminidase (NAG), were estimated in a rural area of Japan. The frequency distribution of NAG activities both in the serum and urine of 1,152 males and females (aged 35 to 87), living in a rural area of Gifu Prefecture in Japan, showed an approximately log-normal distribution. Geometric mean values (with S.D. ranges) in healthy subjects (876 males and females) were 12.61 U/l (9.56-16.63) for serum NAG and 8.05 U/l (4.03-16.07) for urinary NAG. There was no significant difference between those of males and females. Serum and urinary NAG activities increased with advancing ages, and these NAG activities in hypertensive subjects were higher than those in normotensives. Since the serum and urinary levels of several commonly measured cytosolic chemicals were within normal limits, the above results could not be ascribed to tissue necrosis. Thus, the estimation of serum and urinary NAG could be a useful indicator discriminating the essential hypertensive patients from the normal subjects.

Acetylglucosaminidase↗
PubMed1989

Molecular characteristics and physical state of human papillomavirus DNA change with progressing malignancy: studies in a patient with epidermodysplasia verruciformis.

In order to establish the role of human papillomavirus (HPV) in carcinogenesis of epidermodysplasia verruciformis (EV), the presence, the molecular characteristics and the physical state of HPV DNA in a benign lesion, a primary carcinoma and a metastatic carcinoma developing in the same EV patient were studied and compared. Of the 2 HPV DNAs isolated from benign macular lesions, only one (a subtype of HPV 5) was detected in both primary and metastatic tumors. Only one normal species of viral DNA molecule was detected in the benign lesion, whereas most, if not all, viral DNA molecules present in the carcinoma (both primary and metastatic) were aberrant ones. The major viral DNA molecule in the primary carcinoma was a large HPV DNA with duplicated 40% subgenomic segments, and was present as free episomes. The major viral DNA molecule in the metastatic carcinoma was the 40% subgenomic segment itself, lacking the remaining 60% segment of the viral genome, and was integrated within cellular DNA. Thus, HPV DNA was present in tumors at any stage of malignancy, and its molecular characteristics and physical state changed not only with the development but also with the enhancement of malignancy, consistently conserving its defined 40% subgenomic segment as the predominant viral sequences. Our results suggest that HPV 5 may be actually involved in carcinogenesis in EV patients.

Carcinoma, Squamous Cell↗
PubMed1988

Two human papillomavirus DNAs molecularly cloned from a patient with epidermodysplasia verruciformis: restriction maps.

Two distinct human papillomavirus (HPV) DNAs (MY-1 and MY-2) were molecularly cloned from the benign skin lesions of a patient with epidermodysplasia verruciformis. The restriction map of MY-1 was the same as that of HPV 3a. The map of MY-2 appeared to be different from those of any HPVs reported in the literature. MY-2 did not cross-hybridize with MY-1 or the DNAs of HPV types 1, 2 and 4 under stringent conditions.

DNA, Viral↗
PubMed1985

Primary choriocarcinoma of the lung.

Choriocarcinoma was found in the lung of a 34-year-old woman. Examination of the patient's entire body, especially the genital tract, failed to disclose foci of choriocarcinoma other than that in the right lung. After surgery, the levels of human chorionic gonadotropin in the blood and the urine fell. It was concluded that the choriocarcinoma of the lung was, in fact, the primary tumor. The genesis of choriocarcinoma was also studied in ten patients who died after delivery or abortion. Autopsy disclosed trophoblasts in the pulmonary arteries in nine of these ten patients. These findings suggest that primary choriocarcinoma in women is due to pulmonary embolism caused by trophoblasts at the time of abortion or delivery.

Adolescent↗
PubMed1984

Hemangioblastoma of the central nervous system: nature of the stromal cells as studied by the immunoperoxidase technique.

Ten hemangioblastomas of the central nervous system were examined by an immunoperoxidase technique for glial fibrillary acidic protein (GFAP), S-100 protein, and Factor VIII-related antigen to determine the origin of the stromal cells. In seven cases scattered stromal cells were positive for GFAP, and eight cases showed variable numbers of S-100 protein-positive cells. These positive cells were present throughout the tumors. S-100 protein-positive stromal cells corresponded to GFAP-positive cells, but the former were more numerous than the latter. Staining for Factor VIII-related antigen was negative in stromal cells, except in endothelial cells lining capillaries. It was suggested that stromal cells of capillary hemangioblastomas are composed by heterogeneous cell populations.

Adult↗
PubMed1984

Enterohepatic circulation of clioquinol in the rat.

The existence of the enterohepatic circulation (EHC) of clioquinol was confirmed by using paired rats, donor and recipient, which were connected to each other with a bile duct-to-duodenum cannula. The concentrations of clioquinol and its metabolites appearing in the plasma of the recipient following intraduodenal 10 mg/kg dose of clioquinol to the donor were fairly low. However, within 24 h after the administration ca. 12% of the dose was reexcreted in the bile of the recipient as clioquinol glucuronide and ca. 2% in the urine as clioquinol sulfate. From these results and the data of biliary excretion in our previous paper, the glucuronide was found to play a role on the EHC. Further, both in vitro and in situ results suggested that clioquinol glucuronide excreted in the bile may be absorbed partially after return to the parent drug in the intestinal tract and partially as such without deconjugation.

Animals↗