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Biomedical subjects

H Yoshimura

Publications and source records attributed to H Yoshimura.

At least 55 records · Page 3Linked to original sources
PubMed1992

In vivo measurement of spatial dose distribution with thermoluminescent sheet around high dose-rate intracavitary source: application to rectal cancer.

For intracavitary high dose-rate radiation therapy, a thermoluminescent [TL] sheet for in vivo measurement of spatial dose distribution around source has been recently developed. The TL sheet was found to have a linear response with a very wide dynamic range from at least 0.002 cGy to 5000 cGy for 60Co gamma-rays. This TL sheet (40 cm x 50 cm x 200 microns), which is composed of Teflon mixed with BaSO4:Eu doped powder, is very flexible and can be cut to the desired size. In addition, this sheet is easy to handle because of its insensitivity to room light. The spatial dose distribution is displayed in a color mode by using a newly developed TL sheet readout system. For a clinical application, the TL sheet was wrapped on an applicator for intracavitary radiation therapy of a rectal cancer and was inserted into the rectum. The location of the TL sheet could be confirmed with diagnostic X ray film. After irradiation with high dose-rate 60Co source, the in vivo relative dose distribution on the surface of the rectum was determined. This TL sheet provided a convenient means of measuring the relative dose distributions around 60Co sources of various patterns in intracavitary radiation therapy.

Brachytherapy↗
PubMed1992

Evaluation of imaging properties of a laser film digitizer.

In this paper we provide a quantitative assessment of the basic imaging properties of a laser film digitizer. The characteristic curve of the digitizer was determined in terms of the relationship between input optical density and output pixel value. Spatial resolution of the laser digitizer was characterized using the presampling modulation transfer function (MTF), which was measured using a curve fitting technique with an angulated slit. For the noise analysis, we compared the Wiener spectra of uniformly exposed film samples before and after digitization. The effects of different sampling distances and scanning directions were investigated. Our results show that the characteristic curve of the laser digitizer was linear. The presampling MTFs of the digitizer were similar at different sampling distances and were substantially greater in the vertical scanning direction than in the horizontal direction. The noise of the digitized film sample was mainly affected by the presampling MTF and structure noise of the digitizer.

Evaluation Studies as Topic↗
PubMed1992

Promoting effects of cigarette smoke on the respiratory tract carcinogenesis of Syrian golden hamsters treated with diethylnitrosamine.

The potential short-term promoting effects of cigarette smoke on the development of tumors in the respiratory system were investigated in male Syrian golden hamsters. Three groups (1, 2 and 3) of 30 animals each received a single s.c. injection of 100 mg/kg body wt of diethylnitrosamine (DEN) at the commencement of experiment 1. They were then exposed to non-filter cigarette (NC) smoke, filter-tip cigarette (FC) smoke and sham smoke respectively, in a Hamburg II type smoking machine from week 1 to week 12. In addition, groups 4, 5 and 6 (10 animals each) were exposed to the NC smoke, FC smoke or sham smoke respectively, for the same time period without prior DEN treatment. In the DEN-treated groups, epithelial hyperplasias and/or papillomas were induced, the incidences and numbers/animal of these lesions in groups 1 and 2 being significantly increased as compared to group 3 values. In experiment 2, two groups of 25 hamsters each were exposed to cigarette smoke or sham smoke for up to 12 weeks, five animals in each group being killed for immunohistochemical analysis using BrdU antibodies and measurement of lipid peroxides in the lung and serum at weeks 1, 2, 4, 8 and 12. Small aggregations of macrophages (smoke cells) in the lung alveoli was observed in the smoke-exposed group, but no significant increase in the numbers of BrdU positive cells in any compartment of the respiratory system was apparent. Animals of this group showed a tendency for increased lung malondialdehyde levels at weeks 2 and 12, but not weeks 4 and 8.

Animals↗
PubMed1992

Effects of caffeine, nicotine, ethanol and sodium selenite on pancreatic carcinogenesis in hamsters after initiation with N-nitrosobis(2-oxopropyl)amine.

The modulating effects of caffeine, nicotine, ethanol and sodium selenite on development of N-nitrosobis(2-oxopropyl)-amine (BOP)-initiated pancreatic tumors were investigated. Female Syrian golden hamsters were given s.c. injections of BOP (10 mg/kg body weight) or saline alone once a week for 3 weeks and then administered 2000 p.p.m. caffeine, 25 p.p.m. nicotine, 20% ethanol or 4 p.p.m. sodium selenite in their drinking water for the next 37 weeks. Control animals were given tap water alone after BOP initiation. Only the BOP-treated groups developed pancreatic adenocarcinomas and dysplasias. The multiplicity of pancreatic carcinomas was significantly higher (P less than 0.05) in animals receiving caffeine than in the controls. In addition, caffeine treatment slightly increased the incidence of carcinomas. Nicotine and ethanol also showed tendencies to enhance pancreatic carcinogenesis, although there were statistically no significant differences regarding lesion development. In contrast, sodium selenite administration was associated with a tendency for a decrease in the number of carcinomas and dysplasias. Thus, among these chemicals of obvious significance to human life-style, caffeine enhanced the development of pancreatic tumors when administered during the post-initiation phase in this hamster model.

Animals↗
PubMed1992

Computerized scheme for the detection of pulmonary nodules. A nonlinear filtering technique.

To aid radiologists in the detection of lung cancer, the authors are developing a computer-aided diagnosis system that locates areas suspicious for nodules in digital chest radiographs. The system involves a difference-image approach and various feature-extraction techniques. The authors describe nonlinear filters used in the difference-image approach. A morphological open operation and a ring-shaped median filter are applied in the difference-image step for signal enhancement and signal suppression, respectively. Using 60 clinical chest radiographs, the nonlinear filtering method detected approximately 63% of actual nodules with approximately 19 false-positive results per image. The locations of the false-positive detections, however, usually did not coincide with those from the linear filtering method. Thus, by using a combination of the detections from the two methods, the false-positive rate was reduced to two to three per image at a sensitivity of 60%.

Evaluation Studies as Topic↗
PubMed1992

Potential usefulness of computerized nodule detection in screening programs for lung cancer.

RATIONALE AND OBJECTIVE: To alert radiologists to possible nodule locations and subsequently to reduce the number of false-negative diagnoses, the authors are developing a computer-aided diagnostic (CAD) scheme for the detection of lung nodules in digital chest images. METHODS: A computer-vision scheme was applied to photofluorographic films obtained in a mass survey for detection of asymptomatic lung cancer in Japan. Ninety-five patients with abnormal test results who had primary and metastatic lung cancers and 103 patients with normal test results were included. RESULTS: The sensitivity of the computer output was comparable with that of physicians in this mass survey (62%). The computer detected approximately 40% of all nodules missed in the mass survey, but missed 17 true-positive results identified in the mass survey. The CAD scheme produced an average of 15 false-positive findings per image. CONCLUSION: If the number of false-positive results can be significantly reduced, computer-vision schemes such as this may have a role in lung cancer screening programs.

False Positive Reactions↗
PubMed1992

Image feature analysis of false-positive diagnoses produced by automated detection of lung nodules.

RATIONALE AND OBJECTIVES: To reduce the number of false-negative diagnoses by radiologists, the authors are developing a computer-aided diagnosis scheme for detection of lung nodules in digital chest images. In this study, the authors attempted to reduce the number of false-positive diagnoses obtained with a previous computer scheme by incorporating additional knowledge from experienced chest radiologists into the computer scheme. METHODS: The authors applied their previous computer scheme, using less-strict criteria, to 60 clinical chest radiographs; this yielded 735 candidate nodules (23 true nodules and 712 false-positive diagnoses). These candidates were analyzed using region-growing, trend-correction, and edge-gradient techniques to determine measures by which to quantify image features of candidate nodules. RESULTS: The 712 false-positive diagnoses represented various anatomic structures that were located throughout the chest image. From this analysis, we were able to decrease the number of false-positive errors from an average of 12 to approximately 5 per image without eliminating any true nodules. CONCLUSION: Our results show that incorporating knowledge from experienced chest radiologists into the computer algorithm will play an important role in the development of computerized schemes for the detection of pulmonary nodules.

Diagnostic Errors↗
PubMed1992

Enhanced elimination of theophylline, phenobarbital and strychnine from the bodies of rats and mice by squalane treatment.

Our previous study suggested that squalane would be a good candidate for an antidote to reduce the toxicity of drug ingested accidentally at a high dose by enhancing the drug elimination from the body. In the present study, we investigated whether squalane given orally could enhance the elimination of theophylline, phenobarbital and strychnine which were administered parenterally to rats or mice. Squalane increased the fecal excretion of theophylline and reduced the serum level of the drug in rats. Squalane accelerated the fecal excretion of strychnine in mice. These results suggest that squalane may stimulate more the elimination of neutral (theophylline) or basic (strychnine) drugs which should be present in unionized form in intestinal lumen, than that of acidic drugs.

Algorithms↗
PubMed1992

Mechanism of hepatic microsomal oxidation of 11-hydroxy-delta 8-tetrahydrocannabinol to 11-oxo-delta 8-tetrahydrocannabinol. Evidence for hydration of the aldehyde formed.

Hepatic microsomal oxidation of 11-hydroxy-delta 8-tetrahydrocannabinol (11-OH-delta 8-THC) to 11-oxo-delta 8-THC was investigated. Hepatic microsomes from mice, rats, guinea pigs and rabbits catalyzed the oxidation of 11-OH-delta 8-THC to 11-oxo-delta 8-THC together with the formation of dihydroxy-delta 8-THCs oxidized at the 7-position or at the pentyl side chain of 11-OH-delta 8-THC. 11-Oxo-delta 8-THC formed under oxygen-18 gas was analyzed by gas chromatography-mass spectrometry (GC-MS) indicating that molecular oxygen was not significantly incorporated into the aldehyde formed. 11-Oxo-delta 8-THC formed from 11-18OH-delta 8-THC (18O/16O = 0.81 - 1.05) was also found to lose oxygen-18 from the molecule. These results suggest that 11-oxo-delta 8-THC is hydrated in the incubation mixture and the aldehyde oxygen is exchangeable with the oxygen atom of water. When 11-oxo-delta 8-THC was incubated with hepatic microsomes and phosphate buffer containing H2 18O (44 atom%), GC-MS analysis indicated the incorporation of oxygen-18 into the aldehyde recovered from the incubation mixture. The results suggest that the hepatic microsomes may facilitate the hydration of 11-oxo-delta 8-THC and exchange an oxygen atom of the aldehyde group with that of water in the incubation mixture.

Aldehydes↗
PubMed1992

A new metabolite of 2,4,3',4'-tetrachlorobiphenyl in rat feces.

Metabolism in vivo of 2,4,3',4'-tetrachlorobiphenyl (TCB) was further studied using male Wistar rats. When the extract of feces of rats given TCB with chloroform was methylated and applied to gas chromatography (GC)-mass spectrometry (MS), a new metabolite was detected. The structure of this new metabolite was 4-hydroxy-2,5,3'4'-TCB based on both its retention time in GC and comparison of the mass spectrum with that of the synthetic sample. 4-Hydroxy-2,5,3',4'-TCB was assumed to be formed via a 4,5-oxide intermediate followed by NIH-shift of a chlorine atom at 4-position.

Animals↗
PubMed1992

[Comparison of the effects of benzodiazepine and non-benzodiazepine anxiolytics on agonistic behavior in male mice].

The present study investigated whether there is any difference between the effects of benzodiazepine and non-benzodiazepine anxiolytics on agonistic behavior in male mice, using an ethopharmacological technique. Agonistic behavior was evoked using a resident-intruder paradigm. The effects of four doses of the following drugs were assessed in either resident or intruder mice: diazepam (vehicle, 1, 2.5 and 5 mg/kg, p.o.) and tandospirone (vehicle, 2.5, 5 and 10 mg/kg, p.o.). Residents and intruders were drugged on alternate test days, and all animals received different sequences of each of the drug conditions according to a random schedule. The injection-test interval was 30 min. When a resident mice were treated with either diazepam or tandospirone, the frequency of attack bite was suppressed significantly in a dose-dependent manner. When intruder mice were treated with diazepam, attack bites by untreated residents were significantly increased, whereas tandospirone was ineffective. Although diazepam caused a significant decrease in both locomotion and rearing, tandospirone did not cause motor dysfunction. These evidence indicate that tandospirone, a 5-HT1A receptor agonist, has different pharmacological properties from diazepam.

Agonistic Behavior↗
PubMed1992

Metabolism of 2,4,5,2',4',5'-hexachlorobiphenyl with liver microsomes of phenobarbital-treated dog; the possible formation of PCB 2,3-arene oxide intermediate.

1. Metabolism of 2,4,5,2',4',5'-hexachlorobiphenyl (HCB) was investigated in vitro using liver microsomes of one male beagle dog after phenobarbital treatment. 2. Three major metabolites were isolated and identified as 3-hydroxy-2,4,5,2',4',5'-HCB, 2-hydroxy-4,5,2',4',5'-pentachlorobiphenyl (PenCB), and 2-hydroxy-3,4,5,2',4',5'-HCB, by comparison of g.l.c.-mass spectrometry and 1H-n.m.r. data with those of authentic samples. 3. 2-Hydroxy-3,4,5,2',4',5'-HCB was found as a metabolite of 2,4,5,2',4',5'-HCB for the first time using dog liver microsomes. Present result indicate that this metabolite and the dechlorinated PenCB are derived from a metabolic intermediate, namely, 2,3-epoxy-2,4,5,2',4',5'-HCB. 2,3-Epoxide formation is a new metabolic pathway of PCB.

Animals↗
PubMed1992

Pulmonary blastoma. Comparison between its epithelial components and fetal bronchial epithelium.

Three cases of pulmonary blastoma exhibiting biphasic epithelial and stromal patterns, and a case of fetal lung-type adenocarcinoma, were examined by immunohistochemistry and electron microscopy (EM) and compared with fetal bronchial epithelium in order to explore the multidirectional differentiation of their epithelial components. The glandular cells of all four tumors resembled fetal bronchial epithelial cells in the pseudoglandular stage. Neuroendocrine (NE) cells were also present; they were argyrophilic and expressed pan-NE markers, neurosecretory granules and peptide hormones. The neural cell adhesion molecule (NCAM) was strongly expressed on the cell membranes of glandular cells, as in the case of proximal bronchial epithelial cells at the pseudoglandular stage in fetal lung. Sialosylated Lewis X was also expressed, indicating that the epithelial cells were possibly of endodermal origin. Two of the four cases showed considerable immunoreactivity for alpha-fetoprotein (AFP). The epithelial cells of pulmonary blastomas may occasionally de-differentiate into cells functionally resembling fetal hepatic, foregut and yolk sac cells expressing AFP. Tumor examination by immunohistochemistry and EM suggested that the glandular cells of the tumors may differentiate to some extent like those of fetal large bronchi at the pseudoglandular stage, but there was concordance and discordance in the expression of neuroendocrine and oncofetal markers between blastomatous tumors and fetal bronchial epithelium.

Aged↗
PubMed1992

Sex difference in hepatic microsomal aldehyde oxygenase activity in different strains of mice.

Hepatic microsomal oxidation of 11-oxo-delta 8-tetrahydrocannabinol (11-oxo-delta 8-THC) and 9-anthraldehyde (9-AA) to the corresponding carboxylic acids was investigated using six strains of male and female mice (ddN, ddY, C57BL, DBA, C3H and ICR). No significant sex difference was observed in the activity toward 11-oxo-delta 8-THC except for ICR, whereas the activity toward 9-AA was significantly higher in female than in male of ddN, C57BL, DBA and C3H mice. The present study suggests that female specific form(s) of cytochrome P450 may be responsible at least in part for the microsomal oxidation of 9-AA, but not that of 11-oxo- delta 8-THC.

Aldehyde Oxidase↗
PubMed1992

[Studies on cell proliferation activities in acute toxic lesions in the liver and pancreas of hamsters treated with N-nitrosobis(2-oxopropyl)amine].

Histopathology and cell proliferation activities in acute toxic lesions in the liver and pancreas of female Syrian hamsters given a S.C. injection of N-nitrosobis(2-oxopropyl)amine (BOP) at a dose of 100 mg/kg, were investigated. Histologically, at one day after administration, hypertrophy and focal necrosis of the hepatocytes were observed, whereas no remarkable changes were seen in the pancreas. At 7 days after administration, when diffuse hypertrophy, vacuolation and necrosis of the hepatocytes, and atypical hyperplasia of the bile duct were seen in the liver, hyperplasia of the pancreatic duct and focal necrosis and vacuolation of the acinar cells were noticed in the pancreas. Immunohistochemistry for both 5-bromodeoxyuridine (BrdU) and proliferating cell nuclear antigen (PCNA) revealed remarkable increases of cell proliferation activities in the target cells for BOP toxicity, especially at 7 days after BOP treatment. Meanwhile, the number per nucleus of silver-stained proteins related to nucleolar organizer regions (AgNOR) was significantly increased in the target cells at both 1 and 7 days after BOP treatment. Thus, in the present study, it was suggested that acute toxic changes in the liver of hamsters treated with BOP precedes those in the pancreas. The speculation that AgNOR may be an indicator recognizing earlier alterations on acute BOP toxicity remains to be examined.

Animals↗
PubMed1992

[A case of hydropneumothorax].

A 19-year-old girl was admitted because of fever, cough and suddenly occurred chest pain. One month earlier she had experienced a fever and cough, then she had felt sudden chest pain 2 weeks prior to the admission. A chest X-ray showed left pneumothorax and massive pleural effusion. A diagnosis of hydropneumothorax was made. In spite of the chest tube drainage, reexpansion of the lung was unsatisfactory. Thoracotomy and decortication of the lung resulted in good reexpansion. Histological finding revealed pleuritis due to bacterial peribronchial infection, which resulted in hydropneumothorax, namely an abscess ruptured to the pleural cavity.

Adult↗
PubMed1992

Regiochemical differences in cytochrome P450 isozymes responsible for the oxidation of methylenedioxyphenyl groups by rabbit liver.

The cytochrome P450 isozymes catalyzing the oxidation of the methylenedioxyphenyl compounds methylenedioxybenzene (MDB) and methylenedioxyamphetamine (MDA) have been investigated in rabbit liver preparations. The aromatic ring in MDB undergoes both demethylenation to catechol and aromatic hydroxylation to sesamol, whereas that in MDA undergoes only demethylenation to dihydroxyamphetamine. Formation of catechol and sesamol from MDB in microsomal incubation mixtures was enhanced about 5- and 3-fold, respectively, by pretreatment of the rabbits with phenobarbital, which induced CYP2B4 and CYP4B1. The cytochrome P450 isozyme responsible for aromatic hydroxylation of MDB was induced by beta-naphthoflavone and was inhibited by alpha-naphthoflavone. Microsomal demethylenation of MDA was minimally sensitive to pretreatment of the rabbits with phenobarbital, beta-naphthoflavone, pyrazole, or rifampicin. However, MDA competitively inhibited the N-demethylation of erythromycin. Antibodies against CYP2B4, but not those against CYP4B1, caused a marked inhibition of the demethylenation and aromatic hydroxylation of MDB. Antibodies against CYP2C3 did not inhibit the demethylenation of MDA, nor did substrates or inhibitors of the CYP2D family except for bufuralol. MDB and MDA were both capable of forming metabolic intermediate complexes, and the rate of complex formation was accelerated by phenobarbital induction. Reconstitution experiments with CYP2B4 suggested that phenobarbital-inducible complex formation from MDA was not due to the carbene pathway involving the methylenedioxy group but was due to oxidation of the amino group. These results indicate that CYP2B4 oxidizes different regions of methylenedioxyphenyl compounds depending on their structure. MDB undergoes oxidation at the methylenedioxy group (major) and the benzene ring (minor). MDA is oxidized at the alkylamino side chain at the nitrogen and alpha-carbon. The results suggested that one or more constitutive isoforms (probably unknown) of cytochrome P450 present in rabbit liver microsomes are primarily responsible for MDA demethylenation but that CYP3A6 contributes slightly.

3,4-Methylenedioxyamphetamine↗