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Biomedical subjects

Y Miyata

Publications and source records attributed to Y Miyata.

At least 325 records · Page 18Linked to original sources
PubMed1981

Development of sarcomas in heterotopically transplanted rat urinary bladder unit exposed to glucuronic acid conjugate of N-hydroxy-4-aminobiphenyl.

The glucuronic acid conjugate of N-hydroxy-4-aminobiphenyl was tested for carcinogenicity using a heterotopically transplanted rat urinary bladder (HTB) diverted from urine flow. A low-grade transitional cell carcinoma developed in 1 of 16 HTB and sarcoma surrounding the Ommaya reservoir connected to HTB in 8 of 16 rats. This unexpected high incidence of sarcomas, not previously observed in HTB-carcinogenesis model, suggested that the glucuronide conjugate of N-hydroxy-4-aminobiphenyl is a locally active carcinogen to mesenchymal cells.

Aminobiphenyl Compounds↗
PubMed1981

Carcinogenesis in heterotopically-transplanted urinary bladder by N-methyl-N-nitrosourea: a model for initiation and promotion.

The present investigation was conducted to establish a working model to evaluate the role of potential modifiers (promoters and inhibitors) of urinary bladder carcinogenesis. A single dose (0.25 mg) of the carcinogen N-methyl-N-nitrosourea (MNU) when instilled directly into heterotopically transplanted urinary bladder (HTB) induced a 9% (2 of 22) incidence of urinary bladder tumors by 30 weeks in the urine free HTB environment, whereas repeated instillation of urine into the HTB after MNU treatment resulted in a 61% (14 of 23) incidence of these tumors. Three doses of MNU (0.25 mg/dose once a week for 3 weeks) induced 33% (6 of 18) and 89% (16 of 18) incidence of tumors, respectively, in the absence and presence of urine in the HTB. These data confirm our previous observation that normal urine enhances urinary bladder carcinogenesis, and are consistent with the notion that normal urine exerts a tumor promoting effect.

Animals↗
PubMed1981

A new Salmonella serovar: Salmonella itami (9,12:1,z13:1,2).

A new Salmonella serovar, here names Salmonella itami, was isolated from a traveller suffering from gastroenteritis, who had just returned from Thailand. The isolate belonged to the subgenus I of Salmonella, and the antigenic formula was determined to be 9,12:1,z13:1,2.

Humans↗
PubMed1980

Effects of caffeine and saccharin on DNA in the bladder epithelium of rats treated with N-butyl-N-(3-carboxy-propyl)-nitrosamine.

The damage to DNA caused by N-butyl-N-(3-carboxypropyl)-nitrosamine (BCPN), saccharin and caffeine in the urinary bladder epithelium of female rats and its subsequent repair was investigated using alkaline sucrose density gradient analysis with a fluorimetric procedure for DNA determination and light and electron microscopy. Exposure of the bladder epithelium to 50 mg/kg body wt. of BCPN solution for 5 min resulted in serious damage of DNA within 2 h. Subsequent repair of most of the DNA damage, as indicated by reconversion of low molecular weight DNA fragments to larger ones, began after 6 h, and appeared to be complete after 48 h. Caffeine and saccharin induced no remarkable changes in the sedimentation profiles of DNA of the epithelial cells, with or without pretreatment of the cells with BCPN (administered to rats as 0.05% BCPN in the drinking water for 4 weeks). These results were confirmed by light and electron microscopy.

Animals↗
PubMed1980

Selective elimination of motor nerve terminals in the rat soleus muscle during development.

1. The pattern of innervation and either frequency of miniature end-plate potentials (m.e.p.p.s) or acetylcholine (ACh) sensitivity was examined in individual fibres of the soleus muscle in new-born rats to elucidate the mechanism of elimination of motor nerve terminals. 2. the number of motor nerve terminals innervating a muscle fibre was judged by the difference in latencies of end-plate potentials evoked by stimulation of the ventral roots L4 and L5. 3. At early developmental stages, about 50% of soleus muscle fibres were usually singly innervated by the L5 ventral root and this nerve to fibre relation did not change throughout the developmental days. In contrast to the L5 root, the L4 root innervated all the muscle fibres polyneuronally at day 6. In day 16 or older animals, the remaining half of the fibres were singly innervated by the L4 ventral nerves. Therefore, it is concluded that the elimination of motor nerve terminals in the soleus muscle occurs selectively only for the L4 ventral nerves. 4. The number of polyneuronally innervated fibres was increased, to some extent, within 2 days after transection of the spinal cord at day 12. It is suggested that the increased polyneuronal innervation following the inactivity produced by cordotomy may reflect the recovery of terminals which had lost function only a short time previously during elimination. 5. Though frequency of m.e.p.p.s increased from day 6 to adult age as previously reported, there was no significant difference in the frequencies between singly and polyneuronally innervated fibres at any age. Cord transection at day 12 caused no change in the frequency. 6. ACh sensitivity observed in singly innervated fibres was similar to that in polyneuronally innervated fibres. Furthermore, cordotomy on day 12 did not induce an increase in ACh sensitivity around the end-plate. It is concluded that the elimination of terminals is not causally related to changes in ACh sensitivity. 7. The possible mechanisms of selective elimination of terminals and the process of elimination are discussed.

Acetylcholine↗
PubMed1980

Distribution of eyeblink amplitude recorded by an electrode hookup: re-examination.

The present experiment was run to re-examine the distributional properties of the eyeblink amplitude elicited by a burst of 110-dB white noise, recorded by an electrode hookup as recommended in our previous report (Yamada, Yamasaki, & Miyata, 1979). 103 volunteers, 54 males and 49 females, were tested. Analysis showed that the amplitudes were distributed normally when a logarithmic transformation was performed but not when the raw scores were used. We conclude that the amplitude of the startle eyeblink reflex has a log-normal distribution property.

Acoustic Stimulation↗
PubMed1980

[Below-zero habituation of the orienting reflex: study in skin resistance reflex (author's transl)].

Two experiments were designed to investigate a below-zero habituation of the skin resistance reflex (SRR) component of the orienting reflex to auditory stimuli. In both experiments, subjects were given additional ten stimulus-presentations immediately after initial habituation (extended habituation, EH procedure), and they were compared with those without EH procedure. Effects of EH procedure upon rehabituation and SRRs to novel stimuli (Experiment I), and upon SRRs to novel stimuli under an additional control condition (Experiment II), were examined. The EH procedure enhanced SRRs to novel stimuli and had no effects on the spontaneous recovery. These results suggested that habituation would not proceed beyond the zero-level by the EH procedure.

Adolescent↗
PubMed1980

[Skin potential activity under two electrode electrolytes].

To examine whether the basal skin potential levels (BSPL) obtained from habituated and relaxed subjects are determined by a relationship between the electrode electrolyte concentration and the individual values of body fluid electrolyte, the skin potential level (SPL) and reflex (SPR) were measured with 0.06 mol NaCl agar and 0.03 mol KC1 agar as the electrode electrolytes. These electrolyte concentrations were determined in consideration of sodium and potassium concentrations in the palmar tissue. The results showed that under two electrolytes there were no significant differences in relation to SPL and SPR except for the number of SPRs. Therefore, our results support the views on the BSPL mechanism suggested by Christie and Venables (1971 a).

Adult↗
PubMed1980

Inhibitory effect of an aromatic retinoic acid analog on urinary bladder carcinogenesis in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine.

The inhibitory effect of an aromatic retinoic acid analog, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate, on bladder carcinogenesis in rats treated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) was evaluated. Administration of 50 ppm of aromatic retinoid in the diet before BBN in the drinking water reduced the incidence of papillary or nodular hyperplasia as a preneoplastic lesion of the bladder epithelium (P < 0.05). When given before, during or after BBN, it also greatly reduced the incidence of papilloma (P < 0.001 before BBN, P < 0.01 during or after BBN treatment), and slightly inhibited the development of cancer. Administration of 100 ppm of aromatic retinoid before or during BBN administration also reduced the incidences of papillary or nodular hyperplasia (P < 0.01 before BBN, P < 0.05 during BBN treatment), and its administration before, during or after BBN treatment greatly reduced the incidences of papilloma (P < 0.001), and cancer (P < 0.01 before or after BBN, P < 0.001 during BBN treatment). Similar results were obtained by assessing the effect of the retinoid on the average numbers of various epithelial lesions per 10 cm length of basement membrane of the bladder in tissue slices. These results show that the aromatic retinoid inhibits both the initiation and promotion of bladder carcinogenesis induced in rats by BBN, and that its effect is dose-dependent.

Animals↗
PubMed1980

Inhibition by an aromatic retinoid of DNA damage induced by the bladder carcinogen N-butyl-N-(3-carboxypropyl)nitrosamine.

The reversible inhibitory action of an aromatic analog of retinoic acid, ethyl all-trans-9-(4-methoxy-2,3,6-trimethylphenyl)-3,7-dimethyl-2,4,6,8-nonatetraenoate (aromatic retinoid) on bladder carcinogenesis was studied by biochemical and histopathological methods. fischer 344 female rats were fed a diet containing the aromatic retinoid (0, 12.5 or 50 ppm) for 56 days. On day 57, 60 or 70, 50 mg/kg body weight of N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN) in a volume of 0.3 ml was directly instilled intravesically through a urethral catheter. DNA damage in rat bladder epithelial cells 2, 24 and 48 hr after administration of BCPN was examined by measuring the change in sedimentation profile of the DNA in 5 approximately 20% alkaline sucrose gradients. DNA sedimentation was measured by a fluorometric procedure. Histopathological examination of the bladder epithelium was performed at the same time. Two hours after a 5-min exposure to BCPN, DNA damage at the urothelium was observed in rats fed the diet without the aromatic retinoid, but the damage was repaired after 24 and 48 hr. The highest dose of the aromatic retinoid almost completey prevented DNA damage by BCPN on days 57 and 60. A lower dose of the aromatic retinoid did not prevent DNA damage by BCPN on days 57, 60, and 70, while the higher dose did not prevent damage by BCPN on day 70. No histological changes were observed in the urothelium of rats treated with the aromatic retinoid and BCPN, and electron microscopy showed that the epithelium also remained normal. DNA damage was induced by BCPN at the urothelium, and the damage was inhibited by previous administration of the aromatic retinoid.

Animals↗