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T Shimura

Publications and source records attributed to T Shimura.

At least 73 records · Page 4Linked to original sources
PubMed1995

Aversive taste stimuli facilitate extracellular acetylcholine release in the insular gustatory cortex of the rat: a microdialysis study.

The release of extracellular acetylcholine (ACh) in the insular gustatory cortex of conscious rats during taste stimulation was measured using the microdialysis technique. The mean basal release of ACh before stimulation was 273 +/- 21 fmol/10 microliters (mean +/- S.E.M., n = 25). Intraorally applied taste stimuli or distilled water significantly increased the release of ACh. Among them, infusion of 0.001 M quinine HCl produced a marked increase in the release of ACh up to 355% of baseline levels. Infusion of 0.01 M saccharin to the subjects that had acquired an aversion to this taste also caused a prominent increase in ACh up to 343% of basal levels. In contrast, saccharin infusion to the naive subjects moderately increased ACh up to 243% of baseline. Water infusion resulted in the smallest increase in ACh up to 175% of baseline. Although intraoral infusions of quinine or distilled water caused a significant increase in ACh in the parietal cortex, the magnitude of increased ACh was smaller than that in the gustatory cortex. These results suggest that ACh release in the insular gustatory cortex is related to behavioral expression to aversive taste stimuli.

Acetylcholine↗
PubMed1995

10.5-kb homozygote of tumor necrosis factor-beta gene is associated with a better prognosis in gastric cancer patients.

BACKGROUND: In NcoI restriction fragment length polymorphism analysis of tumor necrosis factor-beta (TNF-beta) gene, the frequency of 10.5-kb homozygote is low in patients with lung cancer and is associated with a better prognosis. These results should be examined in other malignancies. METHODS: Using polymerase chain reaction, the authors performed NcoI restriction fragment length polymorphism analysis in 152 patients with gastric cancer, in 69 patients with benign gastric lesion, and in 141 healthy volunteers. RESULTS: In 3-year survival, the 10.5-kb homozygote showed a better prognosis (87.1%) than other alleles (5.5-kb homozygote, 52.5%; heterozygote, 79.1%), and there was a statistically significant difference between the 10.5-kb homozygote and the 5.5-kb homozygote. In 3-year survival for Stages III and IV, the 10.5-kb homozygote also showed a better prognosis (64.9%) than other alleles (5.5-kb homozygote, 16.7%; heterozygote, 41.4%). There were statistically significant differences (10.5-kb homozygote vs. 5.5-kb homozygote, P < 0.01; heterozygote vs. 5.5-kb homozygote, P < 0.05). There was a statistical difference between all patients and Stages III and IV (P < 0.05). CONCLUSIONS: The 10.5-kb homozygote of TNF-beta gene is associated with a prolonged survival in patients with gastric cancer, as has been shown in the patients with lung cancer.

Aged↗
PubMed1995

Conditioned taste aversion in rats with excitotoxic brain lesions.

Conditioned taste aversion (CTA) is well known to be a robust and long-lasting learning after a single conditioned stimulus (CS) (taste)--unconditioned stimulus (US) (malaise) pairing. The neural mechanisms of this taste aversion learning still remain to be resolved. To elucidate the basic brain mechanisms of the taste aversion learning, we examined the effects of lesions of various sites of the rat brain on the acquisition and retention of CTAs. Confined brain lesions were made by injections of a small amount of excitotoxic drug, ibotenic acid. CTAs were established to saccharin (CS) by pairing its ingestion with an i.p. injection of LiCl (US). Rats lacking the parabrachial nucleus (PBN) almost completely failed to acquire CTAs. The second most effective lesion was in the medial thalamus including the parvocellular part of the ventral posteromedial nucleus of the thalamus (VPMpc) and the midline part, followed by the damage of the lateral nuclear group of the amygdala including the basolateral amygdaloid nucleus. Lesions of the gustatory cortex (GC) and hippocampus induced moderate effects, but lesions in the other subnuclei of the amygdala, such as the medial and central amygdaloid nuclei, entorhinal cortex, lateral hypothalamic area, and ventromedial hypothalamic nucleus induced slight or no effects. On the other hand, paired lesions among the amygdala, medial thalamus and GC caused severe impairment of CTAs; in particular, lesions of amygdala and VPMpc completely disrupted acquisition of CTAs. These results suggest that the PBN, medial thalamus and the lateral nuclear group of the amygdala play an essential role in the formation of taste aversion learning.

Animals↗
PubMed1995

HLA and tumor necrosis factor beta gene polymorphisms in Okinawa lung cancer patients: comparative study with mainland Japan lung cancer patients.

The frequencies of HLA class I and II antigens and TNF-beta polymorphism in lung cancer patients were investigated in two areas with different immunogenetic backgrounds, in Okinawa and in mainland Japan (Honshu). In Okinawa frequencies of HLA-Cw3 in squamous cell lung carcinoma patients were higher and those of HLA-DR, both in all lung cancer and in adeno lung carcinoma patients, were lower compared to those of normal controls. Among serologic HLA-DR4-positive individuals, no difference of DRB1*04 gene allele frequency was shown between patients and controls. In Honshu no statistically significant difference of HLA-class I and II alleles frequencies was found; however, the frequency of TNF-beta 10.5-kb homozygote in lung cancer patients was lower than that of controls. For 2-year survival, there was no difference between DR4-positive and -negative individuals and also between each TNF-beta type in Okinawa. In contrast, Honshu patients with 10.5-kb homozygote showed an improved 5-year survival ratio compared to those with heterozygote. We postulate that different immunogenetic backgrounds or environments might have caused the varying HLA or TNF-beta association in the predisposition to or prognosis of lung cancer.

Adenocarcinoma↗
PubMed1995

Validation of transthoracic myocardial ultrasonic tissue characterization: comparison of transthoracic and open-chest measurements of integrated backscatter.

To investigate whether myocardial integrated backscatter (IB) can be measured through the chest wall, myocardial IB parameters were measured in five adult mongrel dogs with a newly developed IB imaging system capable of measurements of myocardial IB relative to backscatter from the blood. There was no significant difference in the calibrated myocardial IB between the closed chest and the open chest conditions either in the septum or in the posterior wall if a 2.5- or 3.5-MHz frequency transducer was used. There was no significant difference in the magnitude of cyclic variation in IB between the closed chest and the open chest conditions independent of the frequency of the transducer used. These data suggest that we can accurately measure not only the magnitude of cyclic variation in IB but also the calibrated myocardial IB through the chest wall with a 2.5- or 3.5-MHz frequency transducer. Such data may validate measurements of myocardial IB parameters through the chest wall even in humans.

Algorithms↗
PubMed1995

Analysis of survival of allogeneic fetal liver fragments in rats.

The survival of allogeneic fetal liver fragments in the omentum was analyzed in rats. The lymphocyte subsets of the spleen and peripheral blood were also examined. When the fetal liver fragments were transplanted into the omentum, they survived for 2 wk, whereas adult liver fragments survived only 1 wk. In fetal liver fragments transplantation, the CD8 positive lymphocyte percentage in peripheral blood decreased significantly 3 wk after transplantation in comparison with that in adult liver fragment transplantation. The skin graft of the donor party showed a longer median survival time in rats receiving fetal liver fragment transplants than that in recipients of adult liver fragments. Although further study is needed, allogeneic fetal liver fragments survived longer in the omentum than reported elsewhere, and the decrease of CD8 positive peripheral blood lymphocytes may have been the reason for this.

Animals↗
PubMed1995

[A case of multiple cerebral aneurysm which showed rapid growth caused by left atrial myxoma].

A 24-year-old woman was admitted complaining of right hemiparesis and episodes of syncope. Computed tomography demonstrated a low density area in the left putaminal region. Intravenous digital subtraction angiography (IVDSA) showed two aneurysms in the distal segment of the right middle cerebral artery. Cerebral emboli from a cardiac source was suspected, and cardioechography was performed. Myxoma was located in the left atrium. The patient was transferred to a cardio surgical unit, and the myxoma was successfully removed. After removal by operation of the cardiac tumor, follow-up third IVDSA was performed. One aneurysm of the distal segment of the right middle cerebral artery had grown larger. On the other hand, the other aneurysm had disappeared. Clipping of the enlarged aneurysm was performed. After the clipping operation of the enlarged aneurysm, a follow-up 4th IVDSA was performed. A new aneurysm of the proximal segment of the left cerebral artery was observed. A follow-up 5th IVDSA was performed, revealing that the new aneurysm was enlarging. No operation was performed, because the aneurysm was the fusiform type. At present, the patient is complaining of slight right hemiparesis and has returned to her job. Here we reported a case of cerebral aneurysm caused by left atrial myxoma.

Adult↗
PubMed1994

Neural substrates for conditioned taste aversion in the rat.

Conditioned taste aversions (CTAs) are well known to be robust and long-lasting instances of learning induced by a single CS (taste)-US (malaise) pairing. CTA can be taken as a general model to search for neural mechanisms of learning and memory. In spite of extensive research on CTAs using a variety of approaches during the last three decades, the neural mechanisms of taste aversion learning still remain unsolved. In this article we propose a model of neural substrates of CTAs on the basis of our recent studies incorporating previous findings by other workers. Our studies mainly included experiments using ibotenic acid injections into various parts of the rat brain as a lesion technique, and c-fos immunohistochemistry in naive and CTA trained rats. CTAs were established by pairing the ingestion of saccharin (CS) with an ip injection of LiCl (US). Behavioral studies have shown that the parabrachial nucleus (PBN), medial thalamus, and basolateral nucleus of the amygdala are essential for both acquisition and retention of CTAs. C-fos studies suggested that association between gustatory CS and visceral US takes place in the PBN. The gustatory cortex (GC) may modify the strength of this association depending on the nature of the CS, viz., novel or familiar. The amygdala is indispensable for the expressions of CTAs. Tastes with hedonic values are stored in the GC in a long-term manner.

Animals↗
PubMed1994

The medial preoptic area is involved in both sexual arousal and performance in male rats: re-evaluation of neuron activity in freely moving animals.

A total of 74 single unit activities was recorded from the medial preoptic-anterior hypothalamic continuum (MPOA) during free copulatory behavior of male rats. Forty-six units (62.2%) showed changed activities during at least one phase of male copulatory movements; 26 units (35.1%) increased in the firing rate during pelvic thrusting; 32 units (43.2%) increased in activity during backward jumping immediately after intromission; only one unit (1.4%) showed decreased firing rate during thrusting and backward jumping; 12 units (16.2%) increased in activity during pursuit of a female; 19 units (25.7%) were suppressed during genital grooming. Furthermore, 67 units (90.5%) showed a significant change in activity throughout a series of copulatory behavior. From the introduction of a female up to ejaculation, relatively large number of units increased in the firing rate above the value during pre-introduction adaptation period. During postejaculatory interval, however, most units decreased in activity below the level during copulation. These results strongly suggest that the MPOA is involved in both sexual arousal and performance in male rats.

Animals↗
PubMed1994

The study of tumor necrosis factor beta gene polymorphism in lung cancer patients.

BACKGROUND: In recent years numerous reports have discussed the relationship between the human leukocyte antigen and lung cancer. However, the genetic background of lung cancer has not yet been precisely clarified. METHODS: To investigate the genetic background of lung cancer, the human leukocyte antigens in 159 normal healthy control subjects and 102 lung cancer patients were studied, and restriction fragment length polymorphism analysis of the tumor necrosis factor (TNF) beta gene in 165 normal healthy control subjects and 135 lung cancer patients was performed. RESULTS: Lung cancer patients showed a high frequency of human leukocyte antigen B61; however, no statistical difference was found. In the lung cancer patients, the TNF beta 10.5/10.5-kb allele was found at a low frequency, 38.5%, compared to 53.3% in normal controls (chi 2 = 7.51, P = 0.011, corrected P = 0.033, relative risk = 0.77). In the relationship between the histologic types and the TNF beta gene, the TNF beta 10.5/10.5-kb allele showed low frequencies: 38.5% in adenocarcinoma, 38.2% in squamous cell carcinoma, and 27.8% in small cell carcinoma, although no statistical difference was shown. In relation to the postoperative survival period, the TNF beta 10.5/10.5-kb allele was associated with prolonged survival. CONCLUSIONS: The TNF beta 10.5/10.5-kb allele may be associated with resistance to lung cancer and with a better prognosis.

Adenocarcinoma↗
PubMed1994

Susceptibility of ebiratide to proteolysis in rat intestinal fluid and homogenates and its protection by various protease inhibitors.

In order to estimate the intestinal stability of ebiratide [H-Met(O2)-Glu-His-Phe-D-Lys-Phe-NH(CH2)8-NH2], a novel adrenocorticotropic hormone (ACTH) analogue, after oral administration, the hydrolytic properties of ebiratide were determined in the rat small intestinal fluid and mucosal homogenates. Ebiratide was extremely stable in the rat small intestinal fluid, while it was degraded in various intestinal mucosal homogenates. Regional differences were observed in its proteolytic properties; e.g., the hydrolytic rates of ebiratide in jejunal and ileal mucosal homogenates were 2-3 times faster than that in duodenal and colonic homogenates. Degradation of ebiratide was markedly inhibited by aminoprotease inhibitors such as sodium glycocholate, puromycin, bestatin and bacitracin. These results suggest that co-administration of certain protease inhibitors are useful to improve the stability of ebiratide in the intestine.

Adrenocorticotropic Hormone↗
PubMed1994

Differences in taste responses to Polycose and common sugars in the rat as revealed by behavioral and electrophysiological studies.

Behavioral and electrophysiological experiments were performed to examine the suggestion that rats have two types of carbohydrate taste receptors, one for polysaccharides (e.g., Polycose) and one for common sugars (e.g., sucrose). Qualitative difference between the tastes of Polycose and sugars including sucrose, maltose, glucose, and fructose was surveyed by means of a conditioned taste aversion paradigm in which the number of licks for 20 s to each taste stimulus was measured. Aversive conditioning to Polycose did not generalize to sugars, while aversive conditioning to sucrose generalized to other sugars, but not to Polycose. In the electrophysiological study, taste responses of the whole chorda tympani were recorded. A proteolytic enzyme, pronase E, suppressed nerve responses to both Polycose and sugars to less than 50%. A novel anti-sweet peptide, gurmarin, strongly suppressed responses to sugars, but had essentially no effect on Polycose responses. On the other hand, KHCO3 enhanced responses to sugars to about 300%, but had little effect on Polycose responses. These results have confirmed the notion that rats can differentiate the tastes between Polycose and common sugars and that rats have two types of carbohydrate receptors.

Animals↗
PubMed1994

Representation of hedonics and quality of taste stimuli in the parabrachial nucleus of the rat.

The distribution of evoked expression of the proto-oncogene c-fos was immunohistochemically examined in the parabrachial nucleus (PBN) of water-deprived rats after free ingestion of palatable liquids, after intra-oral infusion of aversive taste solutions including various bitter substances, and after an intraperitoneal injection of LiCl. C-fos immunoreactive neurons (c-fos neurons) were densely packed in the external lateral subnucleus (els), external medial subnucleus (ems), dorsal lateral subnucleus (dls), central lateral subnucleus (cls), and the central medial subnucleus (cms) depending on the kind of stimulation. The rostral part of the els may be related to general visceral inputs; the caudal part of the els, negative hedonics or aversive behavior; the dls, positive hedonics or ingestive behaviour. Both the ems and the els may be related to taste information for bitter tasting compounds and HCl; the cls, for sucrose and saccharin; and the cms, for NaCl.

Animals↗