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Biomedical subjects

T Aoyama

Publications and source records attributed to T Aoyama.

At least 145 records · Page 8Linked to original sources
PubMed1997

Quantitative rest technetium-99m tetrofosmin imaging in predicting functional recovery after revascularization: comparison with rest-redistribution thallium-201.

OBJECTIVES: This study was undertaken to 1) compare the regional myocardial tracer distributions between rest technetium (Tc)-99m tetrofosmin and rest-redistribution thallium (Tl)-201 images in patients with coronary artery disease and left ventricular dysfunction; and 2) assess the comparative values of these agents for predicting functional recovery after revascularization. BACKGROUND: Tc-99m tetrofosmin is a new myocardial perfusion imaging agent, but its role for detecting viable myocardium is still unclear. METHODS: Thirty-six patients with coronary artery disease and left ventricular dysfunction underwent rest Tc-99m tetrofosmin, rest-redistribution Tl-201 and gated blood pool scintigraphy. In 21 patients with successful revascularization confirmed by follow-up angiography, gated blood pool scintigraphy was repeated after revascularization. Optimal threshold cutoffs to separate reversible from irreversible dysfunction were determined by receive operating characteristic analysis. RESULTS: Regional Tc-99m tetrofosimin activity highly correlated with redistribution Tl-201 activity (r = 0.93). The diagnostic performance for predicting functional recovery, as measured by the area under the receiver operating characteristic curves, measured 0.66 +/- 0.07 (mean +/- SD) for Tc-99m tetrofosmin and 0.67 +/- 0.07 for Tl-201 (p = 0.60, 96.7% power to detect difference in area of 0.10). The optimal threshold cutoffs for viability were considered to be 50% of peak activity for Tc-99m tetrofosmin and 55% of peak activity for Tl-201. The positive and negative predictive values for reversible dysfunction were, respectively, 69% and 82% for Tc-99m tetrofosmin and 69% (p = 0.99 vs. Tc-99m tetrofosmin) and 71% (p = 0.66 vs. Tc-99m tetrofosmin) by Tl-201. CONCLUSIONS: The diagnostic performance of quantitative rest Tc-99m tetrofosmin imaging in predicting functional recovery after revascularization is comparable to that of rest-redistribution Tl-201.

Aged↗
PubMed1997

Pharmacodynamic modeling for change of locomotor activity by methylphenidate in rats.

PURPOSE: The locomotive activity changes after intravenous (i.v.) administration of methylphenidate (MPD) in rats were pharmacodynamically analyzed. METHODS: MPD concentration in plasma, MPD concentration and dopamine (DA) level in striatal dialysate collected by microdialysis method, and the locomotor activity after i.v. administration of MPD (2, 5 and 10 mg/kg doses) were used for the analysis. RESULTS: The transport of MPD from plasma to the interstitial fluid in the brain could be expressed by the linear two-compartment model. The clockwise hysteresis between the MPD concentration and the DA level in the dialysate could be explained by the pharmacodynamic model considering Michaelis-Menten type reuptake process of the extracellular DA into the terminal of the dopaminergic nerve and its competitive inhibition by the extracellular MPD. The inhibition constant (Ki) of MPD for DA reuptake was estimated to be 41.3 +/- 73.8 nM (mean +/- SE), which was closely consistent with the in vitro value after correction with dialysis recovery. The relationship between DA level in dialysate and locomotor activity was expressed by the Emax model considering two contrary effects, hyperkinesia and stereotypy. The bi-phasic locomotor activity-time profiles after high dose of MPD could be represented by this model. CONCLUSIONS: The developed model made it possible to explain the tolerance in DA increase and the complicated locomotive change induced by MPD, and may by useful for other DA reuptake inhibitors, such as amphetamine and methamphetamine.

Animals↗
PubMed1997

Clinical trial of immunostimulation with a biological response modifier in unexplained recurrent spontaneous abortion patients.

We determined clinically whether a killed streptococcal preparation (KSP), a biological response modifier, is as effective as paternal lymphocyte immunotherapy for unexplained recurrent pregnancy abortion (RSA) therapy. The success rate of adverse pregnancy in the study group of 23 RSA cases, who were administered low doses of KSP before and during early pregnancy, was statistically compared with that in a control group of 205 women who received paternal lymphocyte immunotherapy. The association of natural killer (NK) cell activity in the peripheral blood with pregnancy outcome was also assessed. The success rate in the study group was 73.9% (17/23), compared to 75.1% (154/ 205) observed for the controls (not significant). Most of the successful cases exhibited low levels of NK cell activity in the peripheral blood. Immunotherapy with low doses of KSP is as effective as that with paternal lymphocytes, providing a simple and safe alternative therapy for unexplained RSA. Suppression of NK cell activity by some immunoregulatory mechanism was also found to have potential benefit in terms of a successful pregnancy outcome.

Abortion, Habitual↗
PubMed1997

A glucocorticoid-mediated transcriptional induction system in transgenic plants.

A novel chemical induction system for transcription in plants has been developed, taking advantage of the regulatory mechanism of vertebrate steroid hormone receptors. A chimeric transcription of the DNA-binding domain of the yeast transcription factor GAL4, the transactivating domain of the herpes viral protein VP16, and the receptor domain of the rat glucocorticoid receptor (GR). The GVG gene was introduced into transgenic tobacco and Arabidopsis together with a luciferase (Luc) gene which was transcribed from a promoter containing six tandem copies of the GAL4 upstream activating sequence. Induction of luciferase activity was observed when the transgenic tobacco plants were grown on an agar medium containing dexamethasone (DEX), a strong synthetic glucocorticoid. Induction levels of the luciferase activity were well correlated with DEX concentrations in the range from 0.1 to 10 microM and the maximum expression level was over 100 times that of the basal level. Analysis of the induction kinetics by Northern blot analysis showed that the Luc mRNA was first detected 1 h after DEX treatment and increased to the maximum level in 4 h. The stationary induction level and the duration of the induction varied with the glucocorticoid derivative used. The GVG gene activity can also be regulated by DEX in transgenic Arabidopsis plants. The results indicate that a stringent chemical control of transcription can be achieved in plants with the GVG system. Advantages and potential uses of this system are also discussed.

Animals↗
PubMed1997

Cytochrome P450 isozymes responsible for the metabolism of toluene and styrene in human liver microsomes.

1. Cytochrome P450 isozymes from Asian (31 Chinese subjects) and Caucasian (14 Finnish subjects) livers were examined for their roles in the metabolism of toluene (rates of benzyl alcohol, o- and p-cresol formation) and styrene (rates of styrene glycol formation). 2. For toluene, the overall rate of metabolism was higher in samples from Finnish than from Chinese subjects. At 0-20 mM toluene, the rate of o-cresol formation was significantly higher in Finnish microsomes than in Chinese ones. The formation rates of benzyl alcohol and p-cresol in Finnish samples were also higher than those of Chinese samples, but only at a high substrate concentration (5.0 mM). For styrene metabolism, the Chinese liver microsomes showed higher metabolic rates than the Finnish ones at 0.085 mM styrene, but not at the higher substrate concentration. 3. Mean expression levels of immunochemically detected CYP1A2/1 and CYP2B6 were almost 3-fold higher in Finnish microsomes, whereas CYP2E1 was 1.7-fold higher in Chinese samples. 4. Correlation analysis showed that CYP2E1 (benzyl alcohol formation) and CYP1A2/1 (o-cresol formation) contributed to the metabolism of toluene at the low substrate concentration, whereas CYP2C8 was the form more actively involved at the higher toluene concentrations. At the higher concentration (1.8 mM) of styrene, CYP2B6 was most active isozyme to catalyse the formation of styrene oxide from styrene. 5. These results suggest that CYP2E1 and CYP1A2/1 are the main isoforms responsible for the metabolism of toluene at low substrate concentrations in human liver microsomes, CYP2E1 at low styrene concentration, and CYP2C8 and CYP2B6 at high concentrations of toluene and styrene respectively.

Adolescent↗
PubMed1997

Genomic and mutational analysis of the mitochondrial trifunctional protein beta-subunit (HADHB) gene in patients with trifunctional protein deficiency.

Mitochondrial trifunctional protein (TP), an enzyme of beta-oxidation, is a multienzyme complex composed of four molecules of the alpha-subunit (HADHA) containing the enoyl-CoA hydratase and 3-hydroxyacyl-CoA dehydrogenase domains and four molecules of the beta-subunit (HADHB) containing the 3-ketoacyl-CoA thiolase domain. An inborn error of this enzyme complex can cause sudden infant death syndrome, acute hepatic encephalopathy or liver failure, skeletal myopathy, or hypertrophic cardiomyopathy. TP deficiency is classified into two different biochemical phenotypes: one represents the existence of both subunits and the lack of only the 3-hydroxyacyl-CoA dehydrogenase activity and the other represents the absence of both subunits and the lack of all three TP activities, although their clinical features are similar. We have identified two Japanese patients with this disorder. Three enzyme activities of TP were undetectable in fibroblasts from these two patients. We detected two mutations in the HADHB gene from two Japanese patients, an exonic single T insertion which created a new cryptic 5' splice site and a G1331A transition (R411 K). Patient 1 was a compound heterozygote, while patient 2 was a homozygote of a G1331A transition.

Animals↗
PubMed1997

Influence of air flow on the behavior of thoron and its progeny in a traditional Japanese house.

Air flow influence on the spatial distribution of thoron (220Rn) concentration in a typical Japanese traditional house was investigated at various indoor air flow levels. The effect of air flow on the behavior of both thoron and radon progeny were examined simultaneously. Measurements were carried out by using two types of passive monitors, the radon-thoron discriminative monitor and the Radtrak monitor. Thoron and radon progeny were measured by filter grab sampling with ZnS scintillation counting. Under static condition, a horizontal distribution with greatly varied thoron concentrations was found as reported by previous studies. Under turbulent conditions, thoron concentrations in the middle of the room increased and the concentration gradient of thoron gas became lower. An obvious vertical distribution of thoron was also observed. Prominent diurnal variation of radon progeny concentrations was observed whereas that of thoron progeny concentrations was not. Concentration of thoron progeny changed little at different air flow levels, although the thoron gas level at the middle of the room varied significantly. The influence of air flows on detection efficiencies of the two types of thoron monitors were also checked. The mechanism of behavioral change of thoron and its progeny in turbulent atmosphere is discussed.

Air Movements↗
PubMed1997

A long-term follow-up study of serial magnetic resonance images in patients with delayed encephalopathy after acute carbon monoxide poisoning.

Serial magnetic resonance (MR) images were obtained for 18 months in the follow-up of a patient with delayed encephalopathy after acute carbon monoxide (CO) poisoning. The characteristic findings on T2-weighted MR images (T2WI) were high intensity in the bilateral periventricular white matter and pallidal regions, and low intensity in the striatum. Although the neurological symptoms had improved by about 5 months after exposure, the high signal intensity in the white matter remained visible for 18 months. In addition, low signal intensity in the putamen seen on T2WI, which suggested iron deposition, was seen throughout the 18 months.

Acute Disease↗
PubMed1997

Rapid, sensitive and specific diagnosis of Bordetella pertussis using the polymerase chain reaction.

Use of a repetitive DNA sequence of Bordetella pertussis allowed successful detection of the organism by the polymerase chain reaction (PCR). The method was highly sensitive, being able to detect B. pertussis in specimens containing only a few cells. It was also highly specific, with no amplification of specimens containing other organisms, for example Haemophilus influenzae or Neisseria, being observed. A diagnosis could be made within 1 day. The PCR assay was also evaluated in clinical specimens. Among 47 nasopharyngeal specimens obtained from 24 patients with laboratory-confirmed pertussis, 27 were positive by PCR and 19 by culture. In particular, all three bronchial aspirates from one patient with pertussis were positive by PCR, but only one showed positive on culture. Eleven specimens from parapertussis patients and 65 specimens from patients without pertussis tested negative. It was concluded that this newly developed PCR method for the diagnosis of pertussis was more rapid and sensitive than the usual culture method. Polymerase chain reaction could have a major impact on the treatment and control of this infection and would be a useful tool for studying the pathogenesis of B. pertussis infection.

Bacteriological Techniques↗
PubMed1997

Echographic detection of latent severe thrombotic stenosis of the superior vena cava and innominate vein in patients with a pacemaker: integrated diagnosis using sonography, pulse Doppler, and color flow.

Thrombosis of the innominate vein and SVC is a serious complication in patients with pacemakers, inducing pulmonary embolism or SVC syndrome. Venography is the definitive method for its diagnosis; however, it is too invasive for related studies. The purpose of this study was to validate sonography, pulse Doppler, and color flow in detecting noninvasively innominate vein or SVC thrombosis in patients with pacemakers. In 53 patients with pacemakers, the 1 severe SVC stenosis and 18 severe innominate vein stenoses due to thrombosis were diagnosed by digital subtraction angiography. Sonography accurately showed the severe SVC stenosis due to thrombosis, but had limitations on the innominate vein thrombosis. Color flow demonstrated mosaic flow, indicating poststenotic turbulence due to stenosis of the innominate vein and SVC caused by thrombosis in 15 of 16 patients, and pulse Doppler disclosed absence of flow due to complete occlusion of the innominate vein in 2 of 2 patients. Sensitivity and specificity for detecting severe innominate vein stenosis due to thrombosis using combined color flow and pulse Doppler was 94% and 100%, respectively. In conclusion, sonography, pulse Doppler, and color flow allow accurate detection of severe innominate vein or SVC stenosis due to thrombosis, and are therefore useful for the follow-up of patients with a pacemaker.

Aged↗
PubMed1997

Low serum M-CSF levels are associated with unexplained recurrent abortion.

PROBLEM: The purpose of this study was to determine whether the serum macrophage-colony stimulating factor (M-CSF) level is associated with early pregnancy loss in unexplained recurrent spontaneous abortion (RSA) patients. METHOD: We therefore compared preconceptional serum M-CSF levels between unexplained RSA patients and controls. The former comprised 44 bed-rest therapy patients and 43 intradermal immunization (IDI) patients receiving paternal lymphocyte therapy, who had experienced two and three or more consecutive first-trimester pregnancy losses, respectively. The controls were 46 healthy non-pregnant women. We also prospectively studied the association between M-CSF levels during pregnancy and adverse pregnancy outcomes. Sera from a total of 31 pregnant women, including 16 of the bed-rest therapy group and 15 of the IDI therapy group, were collected at the 4th, 6th, and 8th gestational weeks and were measured for M-CSF levels, using the enzyme-linked immunoadsorbent assay (ELISA) method established by Hanamura et al. RESULTS: Serum M-CSF levels were significantly lower in the non-pregnant RSA patients (460.0 +/- 185.6 U/ml; mean +/- SD) than in the control group (726.5 +/- 134.0 U/ml) and also were lower at the 8th, but not the 4th or 6th gestational week in those patients of both the bed-rest and IDI therapy groups whose outcome was pregnancy failure. CONCLUSION: Thus a low level of serum M-CSF was found to be associated with unexplained recurrent pregnancy loss in both the preconceptional and conceptional phases. These results raise the possibility that M-CSF may play an important role in the maintenance of pregnancy and that it can be used as a parameter for determining individuals at risk.

Abortion, Habitual↗
PubMed1997

Intratumoral heterogeneity in prostate cancer demonstrated by volume-weighted mean nuclear volume.

This study was conducted to investigate the degree of heterogeneity of the volume-weighted mean nuclear volume (MNV) calculated from radical prostatectomy specimens, and to evaluate how closely the MNV calculated from transrectal biopsy specimens reflected the overall malignancy. MNV was evaluated using 77 sections of histological specimens from 9 patients who underwent radical prostatectomy at Shizuoka City Hospital between January 1990 and December 1995. The MNV values calculated from radical prostatectomy specimens were compared with those calculated from preoperative transrectal biopsy specimens. MNV was judged to be homogeneous in six cases and heterogeneous in three cases. Of the heterogeneous cases, MNV calculated from the transrectal biopsy specimens was judged to be underestimated in 2 of 3 cases. This study shows that intratumoral heterogeneity of prostate cancer may affect clinical estimates of the grade of malignancy based on the MNV, and indicates the need for a sufficient number of specimens in order to evaluate the MNV by transrectal biopsy.

Adenocarcinoma↗
PubMed1997

Detection of carbamazepine-induced changes in valproic acid relative clearance in man by simple pharmacokinetic screening.

Selecting the optimum dose of valproic acid is difficult because the pharmacokinetics are complicated by inter-patient variability and by effects arising as a result of co-administration with other antiepileptic drugs. The multiple peak approach has been used to evaluate the effect of age, total body weight, dose, gender and comedication (carbamazepine-induced change) on population estimates of valproic acid relative clearance. Routine clinical pharmacokinetic data (n = 479) were collected from 207 epilepsy patients on combination therapy. The data were analysed by a simple steady-state pharmacokinetic model with the use of NONMEM, a computer program designed for population pharmacokinetic analysis that enables pooling of data. NONMEM estimates suggested that the rate of valproic acid clearance in patients receiving concomitant administration of valproic acid and carbamazepine decreased non-linearly with increasing total body weight in the maturation process, and increased non-linearly with increasing valproic acid dose. The clearance in females was 5.7% less than in males. NONMEM estimates also suggested that the rate of valproic acid clearance increased non-linearly with increasing carbamazepine dose. Concomitant administration of valproic acid and carbamazepine with other antiepileptic drugs resulted in an increase in valproic acid clearance of 10%. The final regression model of valproic acid relative clearance was CL = 6.06TBW-0.168 x DOSE0.414 x CBZDOSE0.093 x 0.943GEN x 1.10CO, where CL is the clearance (mL kg-1 h-1), TBW is the total body weight (kg), DOSE is the dose of valproic acid, CBZDOSE is the dose of carbamazepine, GEN = 0 for males and 1 for females and CO = 0 for concomitant administration of valproic acid and carbamazepine and 1 for concomitant administration of valproic acid and carbamazepine with other antiepileptic drugs. This technique can be used to estimate the pharmacokinetic parameters of a population from sparse data collected during routine clinical care and to determine the extent to which patient characteristics influence drug pharmacokinetics.

Adolescent↗
PubMed1997

[Isolation of Legionella pneumophila from 24 hr-home bath water and an eradication trial of the bacteria from the bath].

Contamination of 24 hr home bath with Legionella pneumophila is recently well recognized. Eradication of the water-bath contamination from L. pneumophila and other bacteria is an important matter to prevent the infection because the 24 hr-bathing facility is widely accepted in Japanese houses. Among the 16 bathing water samples we tested, Legionella pneumophia was isolated from 6 cases (37.5%) when the bathing water was not treated with disinfectants. Number of L. pneumophila increased up to 10(3) cfu/ml and total culturable bacterial counts reached to 10(5) cfu/ml within 5 days when the water was not treated. We selected 5 water baths among 6 positive cases to study the bactericidal effect of chlorine. As a result we concluded that the growth of L. pneumophila in 24 hr-water bath could be stopped by the 2 ppm chlorination program every day.

Baths↗
PubMed1997

A depth-dose measuring device using a multichannel scintillating fiber array for electron beam therapy.

The development of a new depth-dose measuring device for electron beam therapy is described. The device employs plastic scintillating fiber detectors inserted in a polymethylmethacrylate (PMMA) phantom in line along an incident electron beam. Output photons from a fiber, the number of which is proportional to the absorbed dose at each depth of the phantom, were converted to an electric signal with a photodiode. Each signal from the photodiode was transmitted to a personal computer through a multichannel analog-digital converter, and was processed to draw a depth-dose curve on the computer display. A depth-dose curve could be obtained in a measuring time of 5 s for each incident electron beam with an energy range between 4 and 21 MeV. The mean electron energies estimated using the curves and the depth-scaling factor for PMMA were consistent with those obtained from conventional depth-dose measurements using an ion chamber and a water phantom. The newly developed system, being simple and not time consuming, could be used routinely for quality assurance purposes in electron beam therapy.

Biophysical Phenomena↗
PubMed1997

Simple, speedy, sensitive, and specific serodiagnosis of pertussis by using a particle agglutination test.

We developed a particle agglutination test (KPA) with poly(gamma-methyl L-glutamate) as the solid particle for measurement of pertussis toxin (PT) antibody. In this study, KPA was assessed as a means of serodiagnosing pertussis, and the results were compared with those of indirect enzyme-linked immunosorbent assay (indirect ELISA) and the microagglutination test. First, four serum samples were collected from each of 21 healthy children: before and 4 weeks after receiving three primary doses of acellular pertussis vaccines and before and 4 weeks after receiving a booster dose. In all 21 vaccinees, a significant rise in PT antibody titers was observed by KPA after each vaccination, and among all 84 serum samples collected, an excellent correlation was demonstrated between the values obtained by indirect ELISA and those obtained by KPA (r = 0.92). Second, paired serum samples were collected at intervals of approximately 2 weeks from 51 patients with culture-confirmed pertussis. A significant increase in titer (fourfold or more) was observed in 39 (76%) patients by KPA, 34 (67%) patients by indirect ELISA, and 23 (45%) patients by the microagglutination test. In acute- and convalescent-phase sera collected from 20 nonpertussis patients, there were no changes in titers by KPA. The KPA procedure was as simple as that of the microagglutination test, and the reaction time was only 2 h (or overnight). In this study, KPA was demonstrated to be a simple, speedy, sensitive, and specific serodiagnostic method for pertussis.

Agglutination Tests↗
PubMed1997

Nonconvulsive status epilepticus during antidepressant treatment.

We report 3 patients who experienced nonconvulsive status epilepticus following generalized convulsions during antidepressant treatment. All showed prolonged confusion with some psychiatric symptoms, and their electroencephalograms (EEGs) showed either bilateral synchronous multiple spike wave discharges or continuous diffuse sharp and slow waves. When diazepam was administered intravenously to 1 patient, the clinical symptoms and EEG improved markedly.

Adult↗