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Biomedical subjects

T Masui

Publications and source records attributed to T Masui.

At least 73 records · Page 4Linked to original sources
PubMed1994

Neu is not involved in N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide- induced bladder carcinoma or 2-amino-4-(5-nitro-2-furyl)thiazole transformation of rat bladder epithelial cells.

Enhanced c-erbB-2/neu expression has been linked with a poor prognosis in human bladder cancer. Previous reports have shown that a point mutation at nucleotide T2012 in the coding region of the transmembrane domain of the rat gene is sufficient to confer transformation potential on this gene. We examined the comparative levels of p185neu as well as the sequence around the hotspot (T2012) of the neu gene of rat bladder cells transformed by 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT) or established in culture from N-[-4-(-5-nitro-2-furyl)-2- thiazolyl]formamide (FANFT)-induced rat bladder tumors. We concluded that increased p185neu expression did not correlate significantly with tumorigenicity. No alterations in nucleotide sequences of the neu gene were observed in either in vitro model.

3T3 Cells↗
PubMed1994

Clonal analysis of glandular stomach carcinogenesis in C3H/HeN<==>BALB/c chimeric mice treated with N-methyl-N-nitrosourea.

The clonal growth of gastric carcinomas was investigated immunohistochemically in C3H<==>BALB/c chimeras using a strain specific antibody. C3H, BALB/c and chimeric mice were given N-methyl-N-nitrosourea 0.5 mg/mice once a week for a total of 10 times by intragastric intubation and observed until week 50. In normal gastric mucosa of the chimeras, each gland was composed entirely of C3H strain specific antigen (CSA)-positive or -negative cells and no mixed glands were found. Cells of all adenomatous hyperplasias and adenocarcinomas in chimeric mice were, in each case, homogeneous for one or other of the parental types, while comprising both surface mucous cell and pyloric gland cell forms. The results clearly suggest that individual cancers are derived from single cells with multi-potential activities and that cellular differentiation of gastric cancer cells occurs secondarily.

Adenocarcinoma↗
PubMed1994

Effects of testosterone, dihydrotestosterone and estrogen on 3,2'-dimethyl-4-aminobiphenyl-induced rat prostate carcinogenesis.

Post-initiation effects of testosterone propionate (TP), alpha-dihydrotestosterone (DHT) and ethinyl estradiol (EE) on 3,2'-dimethyl-4-aminobiphenyl (DMAB)-prostate carcinogenesis in F344 rats have been investigated by administration of each hormone individually or either androgen in combination with EE. DMAB plus TP resulted in induction of invasive adenocarcinomas in the lateral and anterior prostate and seminal vesicles, as shown in a previous study, whereas DHT did not exhibit any positive modulation potential. Administration of EE together with TP produced increased carcinoma incidence in the lateral and anterior prostate, from 17 and 28% to 70% and 80%, respectively. Dorsal prostate tumors, all of the non-invasive in situ type, were also evident in 30% of animals receiving both TP and EE. Rats treated with DHT plus EE, however, did not develop tumors. Our experiment thus provides evidence that estrogen may play an important role in prostate carcinogenesis.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1994

Reperfused myocardial infarctions on T1- and susceptibility-enhanced MRI: evidence for loss of compartmentalization of contrast media.

The purpose of this study was to characterize the contrast caused by a susceptibility MRI contrast agents, on spin echo T2-weighted imaging of reperfused myocardial infarction. Our interest in this model focused on the expected requirement that such agents be compartmentalized in the tissue to cause signal loss on spin echo images, a condition which may not be present in reperfused infarcted myocardium. Accordingly, nine rats were subjected to 2 h of left coronary artery occlusion followed by 3 +/- 0.5 h of reperfusion prior to administration of contrast media. Three sets of MR images were acquired: (a) baseline axial images at the midventricle, both T1-weighted (TR/TE = 300/20) and T2-weighted (TR/TE = 1500/60); (b) T1-weighted images after administering a T1-enhancing agent, Gd-DTPA-BMA (0.2 mmol/kg), to document that contrast media is delivered to the reperfused infarction; and (c) T2-weighted images after administering the susceptibility agent, Dy-DTPA-BMA (1.0 mmol/kg). Gadolinium-enhanced T1 images depicted reperfused infarction as regions with greatly enhanced signal intensity compared with uninfarcted myocardium, indicating that contrast agent was delivered to the infarcted zone. Dysprosium-enhanced T2 images depicted the injury as a region of persistent signal intensity relative to depletion of signal in normal myocardium, consistent with failure of the contrast agent to cause signal loss. Similar infarction sizes were observed for unenhanced T2-weighted images (33 +/- 5%), gadolinium-enhanced T1-weighted images (36 +/- 5%) and postmortem staining (30 +/- 6%); strong correlations (r > 0.9) were noted in comparisons of these data.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

p53 mutations in early neoplastic lesions of the urinary bladder in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine.

Rat experimental models using N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) as an initiating agent have been widely used to study carcinogenic processes in the urinary bladder. In this study, early neoplastic lesions from 10 male F344 rats treated with 0.05% BBN for 16 weeks were analyzed for changes in the H-ras or p53 genes by polymerase chain reaction (PCR)-single strand conformation polymorphism (SSCP) analysis and subsequent DNA sequencing. Lesions were pooled for each of the 10 rats and six showed point mutations in the p53 gene and one in the H-ras gene. These results would indicate that BBN-induced rat urinary bladder carcinomas are similar to human urinary bladder carcinomas with respect to alterations in the p53 and H-ras genes and that p53 gene alterations are relatively early events in rat urinary bladder carcinogenesis induced by BBN treatment.

Animals↗
PubMed1994

DNA adducts in target and nontarget tissues of 3,2'-dimethyl-4-aminobiphenyl in rats.

3,2'-Dimethyl-4-aminobiphenyl (DMAB) is a potent carcinogenic aromatic amine which demonstrates multiorgan tropism in rats. Using polyclonal antibodies against DMAB-DNA adducts, an immunohistochemical procedure as well as an ELISA were applied to investigate the relationship between DMAB-DNA adduct formation and tumorigenicity. Dose-related nuclear staining was observed 24 hr after application of the carcinogen but specificity in terms of sites of tumor development was lacking. No observable decrease in staining intensity was evident in most organs by 168 hr after administration of DMAB. Specific DNA lesions which could be responsible for carcinogenesis were not detected by the 32P-postlabeling method. The tumorigenic response of the ventral prostate in five strains of rats was roughly paralleled by DMAB-DNA adduct levels generated in the tissue. Strong enhancement of bladder tumor development by combined administration of the antioxidants, butylated hydroxyanisole, or butylated hydroxytoluene, with DMAB, was well correlated with an increase in DNA adducts. Our findings so far suggest that DNA adduct formation itself does not determine the carcinogenic organotropism of DMAB. Other factors (including cell proliferation and promotion by exogenous agents) may play important additional roles. For individual target organs or tissues, however, there seems to be a correlation between adduct levels and carcinogenic potential.

Aminobiphenyl Compounds↗
PubMed1994

Occlusion of the posterior humeral circumflex artery: detection with MR angiography in healthy volunteers and in a patient with quadrilateral space syndrome.

OBJECTIVE: The purpose of this study was to evaluate the effectiveness of MR angiography in detecting occlusion of the posterior humeral circumflex artery and to determine if the finding is specific for the diagnosis of quadrilateral space syndrome. SUBJECTS AND METHODS: Two-dimensional fast low-angle shot MR angiography was used to image both shoulders of one symptomatic patient and six asymptomatic volunteers (10 posterior humeral circumflex arteries). RESULTS: With the arm in a neutral position, the posterior humeral circumflex arteries appeared normal on MR angiograms of all subjects. However, when the arm was in abduction, occlusion of the posterior humeral circumflex artery was seen both in the symptomatic patient and in 80% of the asymptomatic volunteers. CONCLUSION: Our data show that occlusion of the posterior humeral circumflex artery is common in asymptomatic volunteers. Thus, MR angiography has no value in the diagnosis of quadrilateral space syndrome.

Adult↗
PubMed1993

Lack of promotion of N-butyl-N-(4-hydroxybutyl)nitrosamine-initiated urinary bladder carcinogenesis in mice by rat cancer promoters.

The effects of dietary exposure to sodium L-ascorbate (Na-AsA), butylated hydroxyanisole (BHA), and diphenyl on the development of urinary bladder tumors in a mouse two-stage carcinogenesis model were examined. Male B6C3F1 mice received 0.05% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in the drinking water for 4 weeks and were then treated with 5% Na-AsA, 1% BHA, or 1% diphenyl for 32 weeks. None of these chemicals enhanced the development of either preneoplastic or neoplastic lesions in the urinary bladder. Furthermore, DNA synthesis levels of urinary bladder epithelium in mice treated with each substance alone for 8 weeks were not elevated significantly, although Na-AsA was associated with a significant increase in the urinary pH value and Na+ concentration. The results indicate that Na-AsA, BHA, and diphenyl do not exert an enhancing influence on mouse bladder carcinogenesis, in clear contrast to the case in the rat.

Animals↗
PubMed1993

Sequencing analysis of Ha-, Ki-, and N-ras genes in rat urinary bladder tumors induced by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) and sodium saccharin.

Male F344 rats were fed N[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (FANFT) for up to 4 wk, then given the basal diet with or without 5% sodium saccharin for up to 100 wk. In a previous study, we demonstrated point mutations in codons 12 and 61 of Ha-ras gene among eleven transitional cell carcinomas (TCC), one undifferentiated carcinoma, and two sarcomas of the urinary bladder (Mol Carcinogen 3:210-215, 1990). In this study, Ha-ras, Ki-ras, and N-ras sequences were examined by polymerase chain reaction (PCR) and direct DNA sequencing. The results confirm the point mutation in codon 61 (CAA to CGA in 5 TCCs and to CTA in one TCC) of the Ha-ras gene. Mutation at codon 12 was not confirmed. No mutation was found in the Ki-ras gene. Sequences of the N-ras gene exons 1 and 2 were determined, and no mutations was detected. These results suggest the involvement of activated Ha-ras gene, but not Ki-N or N-ras gene, in rat urinary bladder carcinogenesis induced by FANFT. Subsequent sodium saccharin administration did not affect the changes in Ha-ras gene.

Amino Acid Sequence↗
PubMed1993

Partial obliteration or blurring of the descending aortic contours: a pitfall on plain chest radiographs.

We report the cause and clinical significance of partial obliteration or blurring of the descending aortic contour on the frontal chest radiographs of patients without pathology in the vicinity of the descending aorta. Among 112 cases, 26 cases (23.2%) showed obliteration or blurring of the contour (positive group). On the corresponding computed tomograph of the positive group, two dominant causes were shown. One was contact between the descending aorta and the left hilar or lower lobe vessels. The second was the adjacent pleura being obliquely orientated to the anteroposterior (A-P) axis. In the latter group, on the lateral chest radiographs, a flattened thorax with a smaller A-P diameter was seen. Identification of left hilar or lower lobe vessels on a frontal chest radiograph or a diminished A-P diameter of the thorax on a lateral radiograph is useful in differentiating these circumstances from true thoracic pathology.

Adolescent↗
PubMed1993

Subchronic oral toxicity study of captafol in B6C3F1 mice.

The effects of subchronic administration of captafol were studied in B6C3F1 mice given dose levels of 0, 0.3, 0.625, and 1.25% in the diet for 12 wk. There was a dose-related decrease in body weight gain during the 12-wk experiment and a loss of body weight in the 1.25% group of both sexes. Whiles the mice given captafol consumed less diet than the control mice, this was not directly dose-related. The relative weights of liver demonstrated a tendency for dose-dependent increase. Light-microscopic examination revealed cytoplasmic vacuolar degeneration, depending in severity on the dosage, in the livers of both sexes given captafol. In conclusion, the findings obtained from the present subchronic toxicity study indicated the liver to be a primary target organ.

Administration, Oral↗
PubMed1993

Enhancing effect of cadmium on rat ventral prostate carcinogenesis induced by 3,2'-dimethyl-4-aminobiphenyl.

The effects of cadmium given at different stages during 3,2'-dimethyl-4-aminobiphenyl (DMAB)-induced rat prostate carcinogenesis were investigated using male F344 rats. Animals were given 10 subcutaneous injections of 50 mg/kg body weight of DMAB or the corn oil vehicle at two-week intervals. In addition, cadmium was administered at doses of 0, 10, or 30 mumol/kg body weight as single intramuscular injection on the 1st day of the experiment or one day after the last injection of DMAB at week 20. Two further groups were subjected to administration of cadmium at 10 mumol/kg at week 20 and then 5 mumol/kg at week 40, or 10 mumol/kg at week 20 and then 5 mumol/kg at weeks 30, 40 and 50. At the termination, 60 weeks after the beginning of the experiment, the incidences and multiplicity of ventral prostate carcinomas in the groups given cadmium plus DMAB demonstrated a consistent tendency for increase over control values (groups receiving DMAB or cadmium alone). The numbers of carcinomas per rat and per unit area of prostate section were significantly elevated in the two groups given low doses of cadmium after cessation of DMAB administration. Cadmium alone also induced a few prostate carcinomas. The influence on development of prostate tumors did not appear to be a result of the induced severe testicular atrophy because serum testosterone levels were not affected. The results indicate that cadmium and DMAB can act synergistically to cause rat prostate carcinogenesis.

Aminobiphenyl Compounds↗
PubMed1993

Induction of glandular stomach cancers in C3H mice treated with N-methyl-N-nitrosourea in the drinking water.

Establishment of an animal model of stomach carcinogenesis in mice was attempted using N-methyl-N-nitrosourea (MNU) in the drinking water. One hundred and forty-eight male 6-week-old C3H mice were given MNU in their drinking water at a concentration of 120 ppm (group 1), 60 ppm (group 2), 30 ppm (group 3) or 0 ppm (group 4) for 30 weeks. At the end of this time, dose-related induction of adenomatous hyperplasias was found. From weeks 31 to 54 adenocarcinomas developed in a dose-dependent manner in groups 1, 2 and 3. In total, 6 well differentiated and 5 poorly differentiated adenocarcinomas as well as 6 signet ring cell carcinomas arose in 15 stomach cancer-bearing animals in group 1, 4 well differentiated and 2 poorly differentiated adenocarcinomas with one signet ring cell carcinoma in 5 mice of group 2 and one well differentiated adenocarcinoma in group 3. In the forestomach, only one squamous cell carcinoma was found at week 54 in group 1 along with a single well differentiated adenocarcinoma in the duodenum. Thus, MNU in the drinking water selectively induced neoplastic lesions in the glandular stomach epithelium of mice.

Adenocarcinoma↗
PubMed1993

Dual mechanisms for change in myocardial signal intensity by means of a single MR contrast medium: dependence on concentration and pulse sequence.

To determine whether gadodiamide injection can provide sufficient enhancement on both T1- and T2-weighted spin-echo magnetic resonance (MR) images of the heart and skeletal muscles, anesthetized rats were divided into five groups. Groups 1-3 received 0.1 (n = 9), 0.3 (n = 8), or 0.5 (n = 8) mmol/kg gadodiamide injection, respectively, and T1-weighted images were obtained. Groups 4 and 5 received 0.3 or 0.5 mmol/kg gadodiamide injection, respectively, and T2-weighted images were obtained. Gadolinium concentration was measured in myocardium by means of inductively coupled plasma-atomic emission spectroscopy. On T1-weighted images, the 0.1 and 0.3 mmol/kg doses produced a dose-dependent increase in myocardial signal intensity proportional to gadolinium concentration. A dose of 0.5 mmol/kg, which correlated with higher gadolinium concentration and did not further increase myocardial signal intensity, prolonged the imaging window. On T2-weighted images, the 0.3 mmol/kg dose caused a transient decrease in myocardial signal intensity; the 0.5 mmol/kg dose produced greater and persistent loss of signal intensity. In conclusion, the changes in signal intensity induced by gadodiamide injection depend on the dose, pulse sequence, and type of tissue.

Animals↗
PubMed1993

Echo-planar MR imaging of normal and ischemic myocardium with gadodiamide injection.

Rapid echo-planar (EP) magnetic resonance (MR) imaging was used to monitor the first pass of a bolus of gadodiamide injection in the hearts of normal rats and rats subjected to left coronary artery occlusion. Inversion-recovery EP imaging combined with a low dose (0.05 mmol/kg) of the contrast agent caused signal enhancement of normal myocardium from 19% +/- 4 to 63% +/- 5 (mean +/- 1 standard error of the mean) of fully relaxed intensity at the peak of the bolus but only slight increase in signal intensity of the ischemic zone. Thus, ischemic myocardium was demarcated as a hypointense zone (cold spot) during passage of the bolus. A higher dose (0.20 mmol/kg) of the same agent caused signal loss of normal myocardium from 100% to 39% +/- 7 of control at the peak of the bolus on gradient-recalled echo EP images, and ischemic myocardium was visualized as a hyperintense zone (hot spot). With either method of monitoring bolus transit, myocardial signal intensity recovered slowly following the peak bolus effect, consistent with substantial extraction of the agent during the first pass through the heart. Use of gadodiamide injection can allow discrimination between ischemic and nonischemic myocardium on both T1- and susceptibility-weighted EP images during bolus transit.

Animals↗
PubMed1993

Magnetic resonance imaging angiography in a case of eclampsia.

We experienced a typical case of eclampsia. After the onset of eclampsia, we performed magnetic resonance imaging angiography (MRI angiography) to estimate the function of the cerebral artery. MRI angiography showed that spasm occurred in many cerebral arteries. The spasm was still observed in some arteries 13 day after the onset of eclampsia. Vasospasm of eclampsia was clearly, easily and noninvasively confirmed in this case by MRI angiography. This observation suggests that MRI angiography is very useful and informative for diagnosis and in treatment of eclampsia.

Adult↗
PubMed1993

Substrate specificity of alkaline proteases from Cephalosporium sp. KM388.

Serine alkaline proteases from Cephalosporium sp. KM388 were specific against esters of aromatic and hydrophobic amino acids. Against oxidized insulin B-chain, the enzymes initially cleaved the site of Leu-Tyr(15-16). The cleavage specificity of KM388 protease D was broader than those of other alkaline proteases, and the site of Arg-Gly(22-23) was cleaved, which is a specific site for trypsin-like protease.

Acremonium↗