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Biomedical subjects

D Yoshida

Publications and source records attributed to D Yoshida.

72 records · Page 4Linked to original sources
PubMed1981

Chromosomal aberrations and sister-chromatid exchanges induced by gaseous nitrogen dioxide in cultured Chinese hamster cells.

Effects of gaseous nitrogen dioxide (NO2) on chromosomal morphology of cultured Chinese hamster V79-H3 cells were investigated. Chinese hamster cells were exposed to NO2 gas in N2 gas at NO2 concentrations of 0, 5, 10, 20, 50 and 100 ppm (v/v) for 10 min at a gas flow rate of 1000 ml/min. Both chromosomal aberrations and sister-chromatid exchanges were increased depending on the NO2 concentration. The effects of sodium nitrite (NaNO2) were also examined in comparison with those of gaseous NO2, and it was found that the effects of gaseous NO2 could not be ascribed to those of nitrous acid. The gas-exposure apparatus used in this experiments seems to be useful for quantitative investigation of the effects of various gaseous materials on cultured mammalian cells or bacterial cells.

Animals↗
PubMed1980

Amino-alpha-carbolines as mutagenic agents in cigarette smoke condensate.

Two mutagenic agents, 2-amino-9H-pyrido[2,3-b)indole and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (amino-alpha-carbolines) have been isolated from cigarette smoke condensate for this study. The former agent varied in amounts from a low of 25 ng/cigarette in the smoke of flue-cured tobacco, to a high of 258 ng/cigarette in a cigarette of Japanese domestic variety. The latter ranged in amounts from 9 to 37 ng/cigarette. The contents of these mutagens in the smoke condensate were positively related to an increase in mutagenic activity of Salmonella typhimurium TA 98.

Carbolines↗
PubMed1978

Mutagenicities of the pyrolyzates of peptides and proteins.

Pyrolyzates of 10 peptides, 10 proteins and 5 naturally-occurring materials were tested for mutagenicity in the histidine-requiring mutants Salmonella typhimurium TA98 and TA100. Significant mutagenic activity was detected with pyrolyzates of most of these materials. The pyrolyzates requred a liver microsomal fraction, as representative of mammalian metabolism, for their detection as mutagens. Among the pyrolyzates tested, the highest mutagenic activity was observed with that of a tryptophan-containing peptide. The pyrolyzate of protein obtained from tobacco leaf also showed mutagenicity. The higher the protein content in the leaf the higher the mutagenic activity of the pyrolyzate. Protein in a tobacco leaf may be the principal precursor of mutagens in tobacco-smoke condensate.

Dietary Proteins↗
PubMed1978

Changes in mutagenicity of protein pyrolyzates by reaction with nitrite.

Pyrolyzates of protein and related materials were treated with nitrite under acidic conditions, and the mutagenic activity toward Salmonella tester strains was determined. After treatment with nitrite in acidic solution, casein pyrolyzate, an extract of roasted chicken meat, tobacco-smoke condensate and some aromatic amines showed appreciable decreases in their mutagenic activities toward Salmonella typhimurium TA 98. Aromatic amines in the pyrolyzates may be changed by nitrite treatment to other forms having no or lower mutagenic activity toward Salmonella typhimurium TA 98. The contribution by aromatic amines to the total mutagenic activity of the pyrolyzates was as high as 80% in both casein pyrolyzate and extract of roasted chicken meat and 50% in tobacco-smoke condensate. Pyrolyzates of protein and related materials did not show a decrease in the mutagenic activity toward Salmonella typhimurium TA 100 with the same treatment.

Genetic Techniques↗
PubMed1977

Mutagenic activity of amino acid pyrolyzates in Salmonella typhimurium TA 98.

Pyrolyzates of 25 amino acids and 5 indole derivatives were tested for mutagenicity in the histidine-requiring mutant Salmonella typhimurium TA 98. Significant mutagenic activity was detected with pyrolyzates of most of the amino acids. These pyrolyzates required a liver microsomal fraction, as representative of mammalian metabolism, to be detected as mutagens. Among the pyrolyzates tested, the highest mutagenic activity was observed with that of L-tryptophan. As little as 10 microgram of the pyrolyzate of L-tryptophan had detectable mutagenic activity toward TA 98. The optimal pyrolysis temperatures for the formation of mutagenic products were shown to be 500 degrees C for L-tryptophan and 600 degrees C for the other amino acids. The results from pyrolyses of some indole derivatives suggest that an amino group at the alpha-position to the carboxyl group of L-tryptophan plays an important role in the formation of mutagens.

Amino Acids↗
PubMedDate not supplied

Evaluation of hepatocellular carcinoma after treatment with transcatheter arterial chemoembolization: comparison of Lipiodol-CT, power Doppler sonography, and dynamic MRI.

BACKGROUND: The purpose of this study was to compare the ability of Lipiodol-computed tomography (CT), power Doppler (PD) sonography, and dynamic magnetic resonance imaging (MRI) in evaluating the therapeutic effect of transcatheter arterial chemoembolization (TACE) on hepatocellular carcinoma (HCC). METHODS: TACE was performed by injecting an emulsion consisting of Lipiodol and a chemotherapeutic drug, followed by gelatin sponge particles, into 54 patients with 84 HCC lesions. Five to 7 days later, Lipiodol-CT, PD sonography, and dynamic MRI were performed. Findings from the three modalities were correlated with relapse within 1 year after TACE. RESULTS: All lesions with blood flow on PD sonography or intratumoral enhancement on dynamic MRI relapsed regardless of the findings with Lipiodol-CT. None of the negatively enhanced lesions on dynamic MRI relapsed regardless of the Lipiodol-CT findings. However, the readers could not evaluate the contrast uptake in 14 lesions that were already hyperintense on the precontrast images. These cases were considered unsuitable for qualitative assessment and reduced the applicability of MRI to 83% of the examined lesions (70 of 84). Although PD sonography perfectly predicted relapse in superficial (0-5 cm from abdominal surface) lesions of the right hepatic lobe, blood flow in deep (>5 cm) or left lobe lesions was undetectable regardless of the occurrence of relapse. As a result, Lipiodol-CT displayed 76.0% sensitivity, 67.6% specificity, and 72.6% accuracy. The sensitivity, specificity, and accuracy of PD sonography were 34.0%, 100%, and 60.7%, respectively. In the 70 lesions in which evaluation was possible, dynamic MRI achieved 100% sensitivity, 100% specificity, and 100% accuracy. CONCLUSION: Of the three modalities, dynamic MRI was the best for evaluating the efficacy of TACE in the treatment of HCC. We also found that superficial lesions of the right lobe are good candidates for PD sonography. However, high signals on precontrast MR images, motion artifacts, and ultrasonic attenuation remain key limitations.

Aged↗
PubMedDate not supplied

Evaluation of the intratumoral vasculature of hepatocellular carcinoma by power doppler sonography: advantages and disadvantages versus conventional color doppler sonography.

BACKGROUND: To determine whether a difference exists in the relative ability of power Doppler sonography and conventional color Doppler sonography to detect the intratumoral vasculature of hepatocellular carcinoma based on lesion size and location. METHODS: Sixty patients with 88 hepatocellular carcinoma lesions that showed tumor staining on angiography and were enhanced on dynamic computed tomography were evaluated. Power Doppler sonography and color Doppler sonography were used to detect the intratumoral vasculature, and their sensitivity to blood flow was evaluated. RESULTS: Power Doppler sonography showed a superior detection rate for lesions smaller than 2 cm and located 4-8 cm from the abdominal surface in the right hepatic lobe as compared with color Doppler sonography (p < 0.01). Neither power Doppler sonography nor color Doppler sonography depicted the intratumoral vasculature of lesions located more than 8 cm from the abdominal surface (n = 14). Both color Doppler imagings exhibited a low detection rate for lesions in the left hepatic lobe (n = 31, p < 0.01). CONCLUSIONS: Power Doppler sonography should be applied in the evaluation of small or intermediate depth lesions because it is more sensitive to these lesions than color Doppler sonography, but it is not useful for left lobe and deep lesions.

Aged↗
PubMedDate not supplied

Mutagenicity of polycyclic aromatic hydrocarbons and quinones on Salmonella typhimurium TA97.

18 polycyclic aromatic hydrocarbons (PAHs) and 7 quinones were tested for mutagenicity using Salmonella typhimurium TA97, TA98 and TA100 with or without metabolic activation. In the presence of metabolic activation, TA97 was more susceptible to mutation than either TA98 or TA100 by many of PAHs tested. PAHs such as 1-methylphenanthrene, fluoranthene, pyrene, benzo[a]pyrene, benzo[e]pyrene and perylene had high mutagenic effects on TA97 in the presence of metabolic activation. 1,6- and 1,8-pyrenequinones were also highly mutagenic on TA97 in the presence or absence of metabolic activation. It appears that pyrene is mutagenic through its metabolic conversion to pyrenequinones.

Animals↗
PubMedDate not supplied

Thyroid storm precipitated by trauma.

A 21-year-old woman presented to the emergency department complaining of head, neck, and abdominal pain after being assaulted. She denied a previous history or significant symptoms of hyperthyroidism. The physical examination was remarkable for lethargy, low-grade fever, tachycardia, facial abrasions, swelling of the anterior neck, and a tremor. A diagnosis of thyroid storm was made. An extensive work up excluded other causes of the patient's tachycardia, altered mental status, and neck swelling. A review of the clinical features and management of thyroid storm is presented. Relatively minor trauma can be a precipitating event for thyroid storm.

Adult↗
PubMedDate not supplied

Changes in the findings of dynamic MRI by preoperative CAF chemotherapy for patients with breast cancer of stage II and III: pathologic correlation.

Preoperative neoadjuvant chemotherapy is essential for treatment of patients with breast cancer who have a large tumor mass and/or regional lymph node involvement, in terms of both tumor shrinkage and further improvement of the survival rate. In order to safely perform breast-conservation treatment for these patients, a detailed diagnostic procedure for precisely evaluating the therapeutic response is needed. Dynamic magnetic resonance imaging (MRI) is thought to be important in the evaluation of responses to neoadjuvant therapy in patients with considerably large tumors, however, few studies have detailed the changes, as depicted by dynamic MRI, that can be expected with neo-adjuvant chemotherapy. The purpose of this study was to document the changes that occur in response to neoadjuvant chemotherapy and to correlate them with the pathological findings observed in the surgical specimen. The study was performed at Kochi Medical School Hospital from 1995 to 1998. The series consisted of 31 patients with stage II and III breast cancer. Prior to and after 1-5 courses of neoadjuvant chemotherapy, dynamic MRI examinations were performed. Eight of the time-intensity curves for the 10 grade 1a tumors flattened during neoadjuvant chemotherapy, while two remained the same. Six of the curves flattened for the 14 grade 1b tumors, 7 remained the same, and one spiked. And for the seven grade 2 tumors, two of the curves flattened and five remained the same (p=0.0340). In the five grade 1 tumors, the mean after/before normalized peak signal intensity ratio was 0.42+/-0.22. In the 18 grade 2 and 8 grade 3 tumors, the mean normalized signal intensity ratios were 0.59+/-0.28, 0.88+/-0.10, respectively (p<0.05). In the 15 tumors that showed shrinkage of the linear enhancement during neo-adjuvant chemotherapy, 10 had no remarkable intraductal spreading and 9 had a negative surgical margin. In the 16 tumors that had no shrinkage of the linear enhancement during chemotherapy, 13 had remarkable intraductal spreading and 12 had a positive surgical margin (p<0.05). It is concluded that dynamic MRI is a valuable tool for determining tumor response and predicting a positive surgical margin. Breast-conservation treatment can be performed for these patients by meticulous assessment using such detailed diagnostic procedures after local tumor control by combined chemotherapy with high dose-intensity.

Adult↗
PubMedDate not supplied

Dynamic MR appearance of benign phyllodes tumor of the breast in a 20-year-old woman.

We describe a 20-year-old woman with benign phyllodes tumor of the left breast. Dynamic MRI demonstrated a multi-lobulated lesion rapidly and markedly enhanced on dynamic studies of contrast-enhanced T1-weighted imaging without washout. Histological examination of an excisional biopsy specimen obtained under local anesthesia disclosed a well-circumscribed multi-lobulated lesion, confirming the diagnosis of benign phyllodes tumor of the breast.

Adult↗
PubMedDate not supplied

Dynamic MR appearance of adenoid cystic carcinoma of the breast in a 67-year-old female.

We describe an adenoid cystic carcinoma on the right breast of a 67-year-old woman. Dynamic magnetic resonance (MR) imaging demonstrated a well-circumscribed round lesion with rapid and marked enhancement on T1-weighted images, without washout of the contrast agent. The enhanced area extended gradually from the margin to the center of the tumor, showing very late enhancement of the tumor center. The findings suggested a tumor with rich stromal component, including adenoid cystic carcinoma of a special type of breast cancer. Histological examination of a lumpectomy disclosed a well-circumscribed tumor consisting of ovoid, trabecular, and irregularly shaped 'nests' of tumor cells, with a focally cribriform pattern. The examination confirmed the diagnosis of adenoid cystic carcinoma of the breast.

Aged↗