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Biomedical subjects

A Oya

Publications and source records attributed to A Oya.

At least 19 recordsLinked to original sources
PubMed2002

Assessment of the hepatic arterial and portal venous blood flows during pregnancy with Doppler ultrasonography.

PURPOSE: The aim of this study was to evaluate whether the dual hepatic blood supply is altered in healthy pregnant women compared with that in nonpregnant women. MATERIALS AND METHODS: Flow wave-forms in common hepatic artery and portal vein were obtained in 67 healthy pregnant women at 10-40 weeks gestation and 22 nonpregnant women by using Doppler ultrasonography. RESULTS: In the nonpregnant group, the mean (SD) hepatic arterial blood flow, portal venous blood flow, and total liver blood flow were 0.57 (0.31) L/min, 1.25 (0.46) L/min, and 1.82 (0.63) L/min, respectively. In the healthy pregnant group, the portal venous blood flow and total liver blood flow significantly increased after 28 weeks gestation. However, the hepatic arterial blood flow remained unchanged during pregnancy. There was no relationship between the hepatic arterial blood flow and the portal venous blood flow. CONCLUSION: The results demonstrated that the hepatic perfusion increased during third trimester compared to nonpregnant level. Because the hepatic arterial blood flow remained unchanged during pregnancy, major determinant of the increase in the hepatic perfusion was the portal venous return. The data suggest that the hepatic arterial and portal venous vascular territories have regulatory mechanisms that allow for independent changes during pregnancy.

Adult↗
PubMed2002

Reproducibility of pulsed Doppler measurements of the maternal renal circulation in normal pregnancies and those with pregnancy-induced hypertension.

OBJECTIVE: To assess the inter- and intraobserver reproducibilities of pulsed Doppler measurements of the maternal renal circulation in normal pregnancies and those affected by pregnancy-induced hypertension. MATERIALS AND METHODS: Color and pulsed Doppler ultrasound was used to measure acceleration time and resistance index in the renal segmental and interlobar arteries. For the investigation of interobserver reproducibility, two sonographers performed measurements blindly in six normal pregnant women and 14 women with pregnancy-induced hypertension between 28 and 36 weeks' gestation. A second group of 10 patients between 30 and 35 weeks' gestation were examined by one sonographer to assess the level of intraobserver reproducibility of measurements. For each patient in this group, the flow waveform was measured three times in succession. Calculations of the intraclass correlation coefficient Ri were used to determine the level of reproducibility. RESULTS: The interobserver Ri and intraobserver Ri for acceleration time in the segmental artery were 0.95 and 0.96 and for the interlobar artery they were 0.97 and 0.98, respectively. For the resistance index, these values were 0.01 and 0.01 in the segmental artery and 0.52 and 0.29 in the interlobar artery. CONCLUSION: Both the inter- and intraobserver reproducibility of acceleration time measurements in the renal segmental and interlobar arteries were clinically acceptable but the equivalent reproducibilities of resistance index measurements were poor.

Adult↗
PubMed2001

Influence of mild hypothermia on delayed mitochondrial dysfunction after transient intrauterine ischemia in the immature rat brain.

The aim of this study was to determine the effect of different maternal thermal conditions during transient intrauterine ischemia on the mitochondrial respiratory activities in the immature rat brain. On 17 days of gestation, transient intrauterine ischemia was induced by 30 min of right uterine artery occlusion under hypothermic (33.5-34.5 degrees C, n=6), normothermic (36.5-37.5 degrees C, n=6), and hyperthermic conditions (39.5-40.5 degrees C, n=6). All of the pups were delivered by cesarean section at 21 days of gestation and cerebral neocortical tissue was sampled 1 h after delivery. The mitochondrial respiration was measured polarographically in homogenates. In the ischemic uterine horn, ADP-stimulated respiration of the normothermia and the hyperthermia groups decreased significantly to 73 and 74% of the non-ischemic controls, respectively. Since non-stimulated respiration remained unchanged, the respiratory control ratio (RCR) of the normothermia and the hyperthermia groups decreased significantly to 59 and 54% of the non-ischemic levels, respectively. In contrast, the mitochondrial respiratory activities of the hypothermia group showed no differences between the non-ischemic and the ischemic uterine horns. The results demonstrate that mild maternal hypothermia ameliorates the cerebral mitochondrial dysfunction in neonatal rats after intrauterine ischemia due to transient uterine artery occlusion and suggest that maternal thermal conditions, particularly during uteroplacental insufficiency, have important implications for the neuropathological outcome of the newborn.

Animals↗
PubMed2001

Hepatitis C virus in blood and dialysate in hemodialysis.

The prevalence of hepatitis C virus (HCV) positivity among hemodialysis patients remains high compared with that of the healthy population, and thus the issue of safety and environmental protection must be addressed. The purpose of this study is to evaluate the dynamics of prehemodialysis and posthemodialysis blood HCV levels and HCV escape to spent dialysate. Because heparin has an inhibitory effect on the reverse-transcription polymerase chain reaction (RT-PCR) assay, a serine protease inhibitor (nafamostat mesilate) was used as the anticoagulant for hemodialysis. High-flux polysulfone membrane dialyzers were used; dialyzer reuse was not performed. Multicyclic RT-PCR was performed for the quantitative detection of HCV. To elucidate HCV escape to spent dialysate, a portion of total spent dialysate was continuously extracted in a sterile fashion using a minutely adjusted syringe pump. No HCV extravasation to spent dialysate was found, although HCV copy numbers were reduced to a statistically significant level in postdialysis blood compared with predialysis levels (P: < 0.05; n = 20). The need to establish standards for risk management in dialysis centers is evident. The data obtained in this study strongly suggest that to minimize the risk for HCV transmission, lower transmembrane pressure (TMP) should be used in the hemodialysis of HCV-positive patients, with fresh polysulfone dialyzers and dialysis settings of 180 to 250 mL/min for blood flow, 500 mL/min for dialysate flow, and less than 18.72 mm Hg for TMP.

Blood↗
PubMed2001

Developmental changes in tolerance to transient intrauterine ischemia in rat cerebral mitochondria.

OBJECTIVE: Mitochondfial respiratory activities were measured in neonatal rat brain to compare the influence of transient intrauterine ischemia in the preterm fetus with that in the term fetus and to evaluate the effect of alpha-phenyl-N -tert-butyl-nitrone treatment. STUDY DESIGN: Intrauterine ischemia was induced by a 30-minute occlusion of the right uterine artery. The control group consisted of term fetuses (20 days old) exposed to normoxia (n = 8) and ischemia (n = 8). For the investigation into maturity effect, preterm fetuses (14 days old) were exposed to normoxia (n = 8) or ischemia (n = 8), and for the alpha-phenyl-N -tert-butyl-nitrone treatment investigation, term fetuses were exposed to ischemia with alpha-phenyl-N -tert-butyl-nitrone (n = 8). All subjects underwent cesarean delivery at 21 days of gestation, and the mitochondrial respiration was measured polarographically 1 hour after delivery. RESULTS: In the control group the neonatal cortical tissue exposed to ischemia showed a significant decrease in mitochondrial activities compared with those in normoxic control animals. In the preterm group the mitochondrial activities of ischemic fetuses were maintained close to normoxic levels. The neonatal mitochondrial deterioration caused by term ischemia was prevented by alpha-phenyl-N -tert-butyl-nitrone. CONCLUSION: The results indicate that preterm fetuses are more capable than term fetuses of maintaining mitochondrial function under conditions of transient intrauterine ischemia and suggest that oxygen derived free radicals may play a crucial role in the development of neonatal neurologic deficit.

Adenosine Diphosphate↗
PubMed2001

[Present and future of vaccines].

It is advised to understand present status of vaccines to start of review history of vaccine development. Any vaccine currently used has some problems to be improved. In addition to the efficacy or safety, cost of vaccine provide a problem. Drugs and Cosmetics Act describes regulations to ensure quality of vaccines. The Minimum Requirement of Biological Products concerns a soft ware of vaccines and GMP regulates hard ware of vaccine production. Some vaccines such as malaria, AIDS, hepatitis C vaccines are on the way of development in the world. New technology such as DNA vaccines or vaccine for application to mucous membranes are being applied. A new concept of vaccine is presented as a prophylactic tools for cancer, auto-immune diseases or allergic diseases which some key proteins are known as triggers.

Animals↗
PubMed2000

Developmental changes in mitochondrial activity and energy metabolism in fetal and neonatal rat brain.

Experiments were undertaken to investigate mitochondrial activity and energy metabolism in the developing rat brain from the late fetal stage to the neonatal stage. Samples of cerebral cortical tissue were obtained from fetuses at 14, 16, 18, and 20 days of gestation, and from pups at 1 h, 1 day and 7 days after birth. Mitochondrial respiration was measured polarographically using homogenates. Fetal and neonatal brains were frozen in situ and fluorometric enzymatic techniques were used for the analysis of ATP, ADP, AMP, and lactate. In the fetal brain, there was a gradual increase in stimulated (+ADP) and uncoupled respiratory rates using glutamate and malate as substrates, from 14 days to 20 days of gestation, together with a moderate increase in ATP concentration and in the sum total of adenine nucleotides, and a significant decrease in lactate. Since non-stimulated (-ADP) respiratory rates did not change with increasing gestational age, the respiratory control ratio appeared to increase over the same period. An increase in mitochondrial activity was more pronounced immediately after birth, together with a marked increase in ATP concentration and in the sum total of adenine nucleotides. The highest rate of mitochondrial respiration was observed in 1-hour-old pups. These results indicate that, in the rat brain, there is maturation of oxidative metabolism in mitochondria that is initiated in late gestation. Acceleration in mitochondrial respiration occurs immediately after birth in order to maintain high-energy phosphate levels, and this may be crucial for the successful outcome of the newborn.

Adenosine Diphosphate↗
PubMed2000

Changes in uterine and ovarian arterial impedance during the periovulatory period in conception and nonconception cycles.

OBJECTIVE: To evaluate whether the Doppler velocimetry of uterine and ovarian arteries during the periovulatory period in conception cycles differs from that in nonconception cycles. DESIGN: Transvaginal color Doppler sonography was used to assess uterine and ovarian perfusion in 63 infertile women during the periovulatory period. RESULTS: In the conception cycles (n = 16), the PI values of uterine arteries at the day of ovulation were significantly less than those in nonconception cycles (n = 47). There were no significant differences in the PI values of ovarian arteries between the conception and nonconception cycles. CONCLUSIONS: In the present study, the conception cycles showed lower vascular impedance in the uterine during the periovulatory period than did the nonconception cycles. This endometrial perfusion presents an accurate noninvasive assay of uterine receptivity that can be used to predict the successful outcome of implantation and to reveal unexplained infertility problems.

Adult↗
PubMed2000

Changes in maternal lipid peroxidation levels and antioxidant enzymatic activities before and after delivery.

OBJECTIVE: Our goal was to characterize the changes in maternal lipid peroxidation levels and antioxidant enzymatic activities before and after delivery. METHODS: Predelivery and 1, 24, and 48 hours post-partum plasma concentrations of malondialdehyde, erythrocyte enzyme superoxide dismutase, glutathione peroxidase and catalase were measured in uncomplicated pregnancies. RESULTS: Malondialdehyde levels increased slightly from predelivery to 24 hours post-partum and then decreased significantly at 48 hours post-partum. At one hour post-partum superoxide dismutase and catalase levels increased significantly to about 125% and 170% of predelivery levels, respectively. Thereafter, these values decreased significantly from one hour to 48 hours post-partum. The relative changes in superoxide dismutase and catalase levels at one hour post-partum compared to predelivery values correlated significantly with the duration of labor. CONCLUSION: The results suggest that the uncontrolled lipid peroxidation caused by reactive oxygen species, which are produced in consequence of tissue reoxygenation, may occur during labor and that prolonged labor, may cause maternal oxidative stress.

Adult↗
PubMed1999

Slow evolutionary rate of GB virus C/hepatitis G virus.

With the aim of elucidating evolutionary features of GB virus C/hepatitis G virus (GBV-C/HGV), molecular evolutionary analyses were conducted using the entire coding region of this virus. In particular, the rate of nucleotide substitution for this virus was estimated to be less than 9.0 x 10(-6) per site per year, which was much slower than those for other RNA viruses. The phylogenetic tree reconstructed for GBV-C/HGV, by using GB virus A (GBV-A) as outgroup, indicated that there were three major clusters (the HG, GB, and Asian types) in GBV-C/HGV, and the divergence between the ancestor of GB- and Asian-type strains and that of HG-type strains first took place more than 7000-10,000 years ago. The slow evolutionary rate for GBV-C/HGV suggested that this virus cannot escape from the immune response of the host by means of producing escape mutants, implying that it may have evolved other systems for persistent infection.

Evolution, Molecular↗
PubMed1999

Pulsed Doppler US findings of renal interlobar arteries in pregnancy-induced hypertension.

PURPOSE: To evaluate whether Doppler ultrasonographic (US) velocimetry in renal interlobar arteries is altered in women with pregnancy-induced hypertension (PIH) compared with that in healthy pregnant and nonpregnant women. MATERIALS AND METHODS: Flow waveform measurements in renal interlobar arteries were obtained in 39 nonpregnant women, 77 healthy pregnant women at 16-40 weeks gestation, and 15 women with PIH at 28-39 weeks gestation by using color and pulsed Doppler US. RESULTS: In the nonpregnant group, the mean (+/- SD) peak systolic velocity, end-diastolic blood flow velocity, resistive index, and acceleration time were 0.34 m/sec +/- 0.08, 0.14 m/sec +/- 0.03, 0.62 m/sec +/- 0.07, and 52.3 m/sec +/- 13.7, respectively. In the healthy pregnant group, the peak systolic and end-diastolic blood flow velocities at 16 weeks gestation had decreased greatly by 40 weeks gestation. However, the values of other indexes in this group did not change with gestational age. In the PIH group, the acceleration time values were greatly prolonged compared with those in the other groups. CONCLUSION: Acceleration time is one of the hemodynamic parameters of substantial upstream stenosis. These findings suggest that severe stenosis or continuous vasospasm in the proximal arteries, such as the main renal artery and segmental artery, might be implicated in the pathogenesis of PIH.

Adult↗
PubMed1998

Full-length GBV-C/HGV genomes from nine Japanese isolates: characterization by comparative analyses.

The genomes of nine GBV-C/HGV isolates from Japanese chronic hepatitis patients were fully sequenced and characterized. They shared 85% nucleotide sequence homology with previously characterized isolates from the US and West Africa. Homology studies and phylogenetic analyses showed that the Japanese isolates formed a third group distinct from the established groups 1 and 2. The genetic distances between the three groups of GBV-C/HGV were very similar to the distances between the two classical swine fever virus (CSFV) serotypes, which suggested that they might belong to a separate GBV-C/HGV serotype. Plot similarity analysis comparing the three groups exposed relatively conserved terminal non-coding regions. Hairpin structures predicted in the Japanese isolates are probably involved in viral replication. The region coding E1-E2-NS-2 showed the least similarity (80%); in HCV the similarity here is only 50% due to its hypervariability. NS-3 and NS-5b that respectively encode the helicase/protease and RNA-dependent RNA polymerase, had a high degree of amino acid homology, suggesting a high degree of functional constraint in this region. The NS-5b nucleotide sequence was highly conserved perhaps because of constraints from RNA secondary structure and/or an open reading frame in the negative strand.

Base Sequence↗
PubMed1997

New variant groups identified from HGV isolates.

We have determined the primary sequence of the 5' noncoding region (5' NCR) and putative helicase regions (NS-3) of hepatitis G virus (HGV) and GB virus C (GBV-C) that were isolated in Japan from suspected cases of nonA-nonB and/or nonA-nonB-nonC viral hepatitis by using RT-PCR, and we compared the newly isolated sequences with three established isolates. The addition of a "G" residue was found at the 5' terminus of all 8 Japanese isolates. These isolates were more clearly distinguished from the prototype viruses by comparison with the 5' NCR sequence than by comparison with the NS-3 region. Our results suggested that at least three distinct genomic variants of HGV exist. Genotyping of HGV by using RT-PCR based on the sequence of the 5' NCR seems highly feasible.

Base Sequence↗
PubMed1997

The sequence element of the internal ribosome entry site and a 25-kilodalton cellular protein contribute to efficient internal initiation of translation of hepatitis C virus RNA.

Translation of hepatitis C virus (HCV) RNA is initiated by internal entry of ribosomes into the 5' noncoding region (NCR). This process depends on genomic elements within the 5' NCR called the internal ribosome entry site (IRES) and may involve host factors. The alpha-branch structure (nucleotides 47 to 67) of the HCV IRES is considered a cis-acting element critical for translation initiation because it is indispensable for translation in vitro (S. Fukushi, K. Katayama, C. Kurihara, N. Ishiyama, F. B. Hoshino, T. Ando, and A. Oya, Biochem. Biophys. Res. Commun. 199:425-432, 1994). In order to further characterize the function of the alpha-branch, we determined whether sequence exchange within the alpha-branch had any effect on translation initiation. An in vitro translation study revealed that the stem sequences of this region played an important role in efficient IRES function. In addition to several HeLa cell proteins, which had a binding affinity for the 5' NCR, a novel 25-kDa protein that specifically interacted with the HCV IRES was discovered. The binding affinity of the 25-kDa protein for the 5' NCR was correlated with the efficiency of translation initiation of HCV RNA, indicating a critical role for the 25-kDa protein in HCV translation.

Animals↗
PubMed1997

Thermographic demonstration of nonshivering thermogenesis in human newborns after birth: its relation to umbilical gases.

This study was undertaken to measure the extent of nonshivering thermogensis (NST) in brown adipose tissue of human newborns receiving routine thermal care and to examine the influence of oxygen levels at birth on the initiation of NST. Fifteen human neonates were studied in an incubator set at 31-31 degrees C. Thermographic measurements were made every 5 seconds for 5 minutes at 10 and 30 minutes, 1, 3, 6 and 24 hours, and 3 days after birth. The skin temperature and rate of heat dissipation from the interscapular area (location of subcutaneous brown adipose tissue), whole back area, and head area were measured. A heat dissipation ratio (HDR) was calculated as (A-B)/B, where A and B, expressed in Cal/cm2/h, represent rates of heat dissipation from the interscapular area and the whole back area, respectively. Umbilical arterial blood gases were measured immediately after birth. The skin temperature of the interscapular, whole back, and head areas increased significantly during the interval from 10 minutes to 1 hour after birth (p < 0.05). The skin temperature of the interscapular area was highest among the sampled sites during the first hour after birth (p < 0.05). The HDR was highest 10 minutes after birth (p < 0.05). By 1 hour after birth the temperature had reached constant values with low HDR. There was a negative correlation between the HDR and the temperature of the whole back area (p < 0.001). A positive correlation was found between the HDR within 30 minutes after birth and the PO2 of the umbilical arterial blood (p < 0.001). The data support the conclusion that nonshivering thermogenesis is initiated within minutes of birth and contributes to the elevation of body temperature. Furthermore, nonshivering thermogenesis after birth is reduced by low arterial PO2 at the time of birth.

Adult↗
PubMed1996

Nucleotide sequence of the 5' noncoding region of hepatitis G virus isolated from Japanese patients: comparison with reported isolates.

The nucleotide sequences of the 5' noncoding region (NCR) of hepatitis G virus (HGV) from sera of Japanese patients were determined. Among these isolates, there was a high degree (> 96.9%) of sequence identity, whereas identity with previously reported GB virus-C or HGV strains was low (> 87.0%). Phylogenetic analyses showed that the HGV strains from Japanese patients clustered in groups distantly separated from previously reported strains. Among the Japanese HGV isolates, the genetic distances corresponded to subtype differences observed within hepatitis C virus (HCV) isolates, whereas the differences between the Japanese isolates and the prototypes corresponded to genetic distances observed between HCV genotypes. The Japanese HGV isolates found in this study should be placed in a new genotype distinct from previously described isolates.

Base Sequence↗
PubMed1996

Antibody responses in volunteers induced by nasal influenza vaccine combined with Escherichia coli heat-labile enterotoxin B subunit containing a trace amount of the holotoxin.

Evaluation of the efficacy of nasal influenza vaccine combined with Escherichia coli heat-labile enterotoxin B subunit (LTB) containing a trace amount of the holotoxin (LT) in inducing antibody responses among volunteers, which was conducted during the winter season of 1993-1994, is reported. A trivalent inactivated vaccine, composed of A/Yamagata/32/89 (H1N1), A/Kitakyusyu/159/93 (H3N2) and B/Bangkok/163/90 influenza virus strains, was used alone or together with the adjuvant, recombinant LTB supplemented with 0.5% recombinant LT (LTB*). The volunteers were divided into two groups: 73 volunteers (mean age 35.0 +/- 12.0 years) inoculated intranasally (i.n.) with LTB*-combined vaccine and 49 volunteers (37.9 +/- 11.3) inoculated i.n. with the vaccine alone. Vaccination was done twice 4 weeks apart. Salivary secretory IgA and serum hemagglutination-inhibiting (HI) antibodies were measured before and 8 weeks after the primary vaccination. For the sake of convenience, more than a 1.4-fold rise in IgA antibody response (units of specific IgA antibody per microgram of total IgA) and a fourfold or greater rise in HI antibody titer after vaccination were regarded as a positive antibody response. Thirty-seven (50.3%) and 36 (49.3%) of the 73 vaccinees, respectively, given the nasal LTB*-combined vaccine showed positive IgA and HI antibody responses to one or more of the three vaccine strains. In comparison, positive antibody responses in the group given vaccine alone were 32.7% for IgA and 30.6% for HI antibody. There was a significant difference between these two groups. These results suggest that the nasal LTB*-combined vaccine could enhance the production of higher levels not only of serum HI antibody but IgA antibodies in the respiratory tract than do the nasal vaccine alone.

Adjuvants, Immunologic↗