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Biomedical subjects

M Shibata

Publications and source records attributed to M Shibata.

At least 739 records · Page 41Linked to original sources
PubMed1983

Promoting effect of sodium o-phenylphenate and o-phenylphenol on two-stage urinary bladder carcinogenesis in rats.

The effects of sodium o-phenylphenate (OPP-Na) and o-phenylphenol (OPP) on 2-stage urinary bladder carcinogenesis in F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) at levels of 0.01 or 0.05% in drinking water were investigated. Administration of 2.0% OPP-Na in the diet significantly increased both the incidence and the number per 10 cm of basement membrane of preneoplastic lesions (papillary or nodular hyperplasia; PN hyperplasia) of the urinary bladder in rats pretreated with 0.01% BBN, and also those of papilloma and cancer of the urinary bladder in the group pretreated with 0.05% BBN. Moreover, treatment with 2.0% OPP-Na, without prior BBN initiation, induced PN hyperplasia, papilloma and cancer. In contrast, OPP appeared to produce only a slight increase in the incidence of urinary bladder lesions following BBN, and its effect was not statistically significant. It also did not induce tumors of the urinary bladder. These results provide evidence that OPP-Na has promoting activity toward the urinary bladder while OPP does not. Moreover, the possibility that OPP-Na may be a complete carcinogen in the rat urinary bladder deserves consideration.

Animals↗
PubMed1983

Facilitation of thermoregulatory heating behavior by single cortical spreading depression in the rat.

Effects of single waves of unilateral cortical spreading depression (CSD) on skin-heating behavior were studied in the rat with the unilateral lesion in the preoptic and anterior hypothalamus (PO/AH). A single CSD contralateral to the PO/AH lesion significantly increased the number of heating for 4 min after CSD had entered the frontal cortex with a maximum facilitation rate 20% above the pre-CSD level. On the other hand, a single CSD ipsilateral to the PO/AH lesion slightly augmented the number of heating for 2 min with a maximum increase of 8% above the pre-CSD level. An injection of 0.9% NaCl (non-CSD trial) did not affect the skin-heating behavior. The present results, together with the changes in skin-cooling behavior during CSD reported previously, suggest the involvement of the frontal cortex in the central control of thermoregulation.

Animals↗
PubMed1983

[Evaluation of left ventricular asynergy by two-dimensional echocardiography: comparison between fixed external axis system and floating axis system].

Detection and quantitative estimation of segmental asynergy in the infarcted area has been impeded by the rotation and anterior movement of the heart during systole. In the present communication, we compared the two measurements determined by the floating and fixed external axis systems. The former takes into account of the effect of cardiac movement. Furthermore, we assessed which system is superior by the left ventriculographic and coronary arteriographic analyses. The materials consisted of 24 cases of myocardial infarction. There was no significant difference between the two systems in the estimation of the number of asynergic segments or between echocardiographic and ventriculographic findings. The floating axis system had a tendency to underestimate asynergy, so that the number of hypokinetic segment estimated by the floating system was greater than that by the fixed external axis system. Therefore, the fixed external axis system was superior to the floating axis system in determining the causative coronary artery.

Adult↗
PubMed1983

Promoting effects of sodium L-ascorbate on two-stage urinary bladder carcinogenesis in rats.

The promoting effect of sodium L-ascorbate on two-stage urinary bladder carcinogenesis in F344 rats initiated with N-butyl-N-(4-hydroxybutyl)nitrosamine at levels of 0.01 and 0.05% in drinking water was studied. Administration of 5.0% but not of 1.0% sodium L-ascorbate in the diet significantly increased the incidence and number of preneoplastic lesions, papillary or nodular hyperplasia, papilloma, and cancer of the urinary bladder. In groups given 5.0% sodium L-ascorbate, the urine was characterized by an apparent elevation of pH, a decrease of osmolality, and an increase of MgNH4PO4 crystalline. Addition of sodium L-ascorbate to the diet also resulted in increase in the content of ascorbic acid and its metabolite, dehydroascorbic acid, in the urine. These results show that an extremely high dose of sodium L-ascorbate (5.0%) promotes urinary bladder carcinogenesis under the present experimental conditions, while a high dose (1.0%) does not.

Animals↗
PubMed1982

Effect of pH on the kinetics of bovine liver glutamate dehydrogenase self-association.

The temperature-jump technique with light-scattering detection was applied to the kinetic study on the self-association of bovine liver glutamate dehydrogenase (EC 1.4.1.3). The measurements were carried out for systems in phosphate buffer of differing pH, 6.3-7.8, and of differing phosphate concentration at 11.5 degrees C. The observed association rate constant decreased with increasing phosphate concentration at the respective pH values. This observation was interpreted in terms of the inhibition from self-association by specific binding of phosphate ion to the protein. According to this interpretation, the intrinsic association rate constant, k(0)a, and the binding constant of phosphate ion, Kp, were estimated. k(0)a varied with pH in a manner as described by a titration curve with pK of about 7, while Kp remained almost constant in the pH range studied.

Animals↗
PubMed1982

Hippocampal input to preoptic thermosensitive neurons in the rat.

The effects of electrical stimulation of ventral subiculum (VSB) of the hippocampus on the thermosensitive neurons in the preoptic area were studied in urethane-anesthetized rats. VSB stimulation affected thermosensitive neurons more frequently (92.1%, 58 of 63) than thermally insensitive neurons (71.4%, 55 of 77). The majority of the VSB-responsive thermosensitive neurons (33 of 44 warm-units and 11 of 14 cold-units) were initially inhibited following stimulation. The result provides further support for the involvement of hippocampus in the central control of thermoregulation.

Animals↗
PubMed1982

Effects of cortical spreading depression on hypothalamic thermosensitive neurons in the rat.

Effects of unilateral cortical spreading depression (CSD) on the activities of thermosensitive neurons in the ipsilateral preoptic area and anterior hypothalamus (PO/AH) were studied in urethane-anesthetized rats. When a single wave of CSD invaded the frontal cortex, 22 of 25 warm-units were inhibited and all the 13 cold-units were facilitated for 1.2 - 14.2 min. These altered activities of PO/AH thermosensitive neurons may explain, at least in part, the changes of thermoregulatory behaviors and metabolic heat production in the rat with a unilateral PO/AH lesion during CSD of contralateral frontal cortex.

Animals↗
PubMed1982

Comparison of anterior hypothalamic and preoptic thermosensitive neurons in vitro.

Single-unit studies of neurons in anterior hypothalamic (AH) slices and medial preoptic (MPO) slices in vitro isolated from each other revealed that thermosensitive neurons found in both slices have essentially the same properties. Quantitative differences observed were that AH neurons had lower firing rate at neutral temperature and AH warm-sensitive neurons had higher threshold temperature above which the neurons were thermosensitive. Some of AH and MPO warm-sensitive neurons tested did not lose their thermosensitivity in Ca2+-deficient solution. Thus, the primary warm-sensitive neurons having inherent thermosensitivity exist in the AH as well as MPO.

Animals↗
PubMed1982

Gas chromatographic-mass spectrometric analysis of organic acids in renal tissue biopsy: identification of 4-hydroxybutyric acid and 4-hydroxy-2-butenoic acid.

The organic acids in renal tissue biopsy (0.5-1 mg) obtained from chronic glomerulonephritis patients were analyzed capillary column gas chromatography--mass spectrometry. Some twenty compounds were identified in the renal tissue. The organic acid profile of renal tissue showed a marked difference from those of urine and serum. In particular, 4-hydroxybutyric acid and 4-hydroxy-2-butenoic acid, which are usually undetectable in urine and serum, were detected for the first time in renal tissue in considerably large amounts.

Biopsy↗
PubMed1982

Role of amygdala in feeding and drinking induced by single cortical spreading depression in the rat.

Possible involvement of the amygdala in feeding and drinking induced by a single wave of unilateral cortical spreading depression (CSD) was studied in rats. (1) Control animals started their first feeding or drinking in a peak one min after CSD, elicited from the occipital cortex, had expired at the boundaries of the frontal cortex. (2) The peak onset of feeding and drinking mentioned above coincided with the CSD entrance of the amygdala. (3) The peak onset of feeding, but not drinking, remained unchanged in the group with the amygdala lesion contralateral to CSD. (4) Mean incidence of feeding was lower in the group with the amygdala lesion ipsilateral to CSD than in the contralateral group. (5) Results are discussed in relation to the amygdalo-hypothalamic as well as cortico-hypothalamic interaction.

Amygdala↗
PubMed1982

Responses of preoptic thermosensitive neurons to medial forebrain bundle stimulation.

Single-unit responses of neurons in the preoptic and anterior hypothalamus (PO/AH) to local thermal stimulation and electrical stimulation of the medial forebrain bundle (MFB) were studied in urethane-anesthetized male rats. In a total of 286 units (112 warm-units, 37 cold-units and 137 thermally insensitive units), 109 units (49 warm-units, 13 cold-units and 47 thermally insensitive units) responded to single pulse stimulation of MFB. The units initially inhibited by MFB stimulation corresponded to 64.2% (70 of 109), the units with facilitatory responses were 27.5% (30 of 109) and the antidromically activated units were 8.3% (9 of 109). High incidence of inhibition by noradrenaline (NA) applied iontophoretically was observed in the neurons inhibited by the MFB stimulation. Iontophoretic application of dichloroisoproterenol to 2 warm-units blocked both the NA-induced inhibition and the MFB-induced inhibition. These ascending and descending connections of the MFB with PO/AH thermosensitive neurons may be part of the neural circuits responsible for thermoregulation.

Animals↗