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Biomedical subjects

Y Shishido

Publications and source records attributed to Y Shishido.

32 records · Page 2Linked to original sources
PubMed1992

Stimulation of arachidonic acid metabolism by a streptococcal preparation (OK-432) in rat peritoneal macrophages.

A streptococcal preparation OK-432 is reported to be an immunopotentiator and a potent antitumor agent. In order to elucidate the mechanism of biologic action, effects of OK-432 on arachidonic acid metabolism in rat peritoneal macrophages were investigated. Prostaglandin E2 production and release of radioactivity from [3H]arachidonic acid-labeled macrophages were found to be stimulated by OK-432 in a concentration-dependent manner (5 to 80 micrograms/ml). Heat-treatment of OK-432 further stimulated its effects. These stimulative effects on arachidonic acid metabolism by OK-432 were not observed in MDCK cells that have no phagocytotic activity. Furthermore, cytochalasin B treatment completely suppressed the stimulative effects induced by OK-432 in macrophages. These results strongly indicate that the stimulative effects by OK-432 on arachidonic acid metabolism are dependent on phagocytosis of OK-432 particles. Significance of stimulation of arachidonic acid metabolism in macrophages by OK-432 for its biological effects is discussed.

Animals↗
PubMed1992

Voltage-dependent modification of Vmax recovery from use-dependent block by pirmenol in guinea pig papillary muscles: comparison with other class I drugs.

Voltage-dependent modification of Vmax (the maximum upstroke velocity of the action potential) recovery from use-dependent block (UDB) by pirmenol was examined and compared with those observed with other Class I drugs using standard microelectrode techniques. A partial depolarization of the resting membrane by increasing extracellular potassium concentration ([K+]o) from 4 to 8 mM potentiated UDB at 2 Hz stimulation by any of the following drugs: pirmenol (10 microM), disopyramide (20 microM), pentisomide (50 microM), quinidine (20 microM), mexiletine (30 microM), and flecainide (5 microM). The recovery time constants from UDB of quinidine and mexiletine were prolonged and that of flecainide was unchanged in 8 mM [K+]o. However, the recovery time constant from UDB of pirmenol was shortened in high K+ solution, as observed with disopyramide and pentisomide. Thus, disopyramide and its analogues, including pirmenol, show a voltage dependency of recovery process, which is different from those of other class Ia, Ib, and Ic drugs. The main unblocking pathway of disopyramide and its analogues from sodium channels during diastolic interval may be different from that of other Class I drugs.

Action Potentials↗
PubMed1985

Effects of colchicine on the ultrastructure of mouse taste buds.

Effect of colchicine on the ultrastructure of taste bud cells was studied in the mouse. In untreated mice microtubules were abundant throughout the entire cytoplasm of type-III cells, but only in the apical cytoplasm of type-I cells. After 2 h of colchicine treatment, no microtubules were observed in any taste bud cells; dense secretory granules in the apical cytoplasm of type-I cells mostly disappeared, and instead, numerous phagosomes appeared. It is suggested that colchicine causes an interruption of the transport of the secretory granules in type-I cells from the Golgi apparatus to the membrane of the apical surface, from which release occurs. In type-III cells, after 4 or 5 h of treatment, dense-cored vesicles scattered throughout the cytoplasm tended to increase in number; they were often observed to accumulate in the vicinity of the Golgi apparatus. Five hours after treatment with 5-hydroxy-L-tryptophan (5-HTP) following colchicine pretreatment, monoamine specific fluorescent cells and vesicles with highly electron-dense cores of type-III cells were still present. On the other hand, 5 h after 5-HTP treatment alone both fluorescent cells and vesicles with highly electron-dense cores had already disappeared. These observations suggest that the treatment with colchicine interrupts the transport of dense-cored vesicles of type-III cells to synaptic areas, in which those vesicles are presumed to discharge the neurotransmitter substance.

Animals↗
PubMed1985

Diagnosis of submucosal tumors by injecting a water soluble contrast medium: diagnosis of extra-gastric tumors and gastric varices.

Extra-gastric compression caused tumescent lesions that are difficult to differentiate from gastric submucosal tumors, and gastric varices similar in appearance to circumscribed tumors were sometimes experienced clinically. Up to now, the differential diagnosis of these lesions has been done by the palpation through x-ray examination or the tactile test under endoscopic examination. Even by the recent use of the CT scan, the differential diagnosis still remains unsatisfactory except in a few specific cases. Under these present circumstances, submucosography is recommended for routine screening test for outpatients. Our method is simple, safe and time-saving. Recently, it has become easy to diagnose hemangiomas as well as varices in the stomach by application of submucosography. Accordingly, in the cases of vascular tumors or tumescent lesions caused by extra-gastric compression, the risk of incidental major bleeding or perforation can be prevented by using the submucosography.

Adult↗
PubMed1982

Monoamines of taste buds in the fungiform and foliate papillae of the mouse.

After administration of monoamine precursors, taste buds in the fungiform and foliate papillae of the mouse were observed by means of electron microscopy and fluorescence histochemistry. The taste buds in the fungiform papillae differed in the ultrastructure of their apical regions from those in the foliate papillae, which contained the same taste buds as those described in the circumvallate papillae. The gustatory cells in both the fungiform and foliate papillae were capable of taking up monoamine precursors, although this ability was greater in the latter papillae. The results suggest that, not only in the circumvallate papillae but also in both the foliate and fungiform papillae, monoamines might be involved in neurotransmission from the gustatory cells to the nerves.

Amines↗
PubMed1981

Biogenic monoamines in developing taste buds of mouse circumvallate papillae.

After administration of monoamine precursors, developing taste buds of newborn and young mice were observed by means of electron microscopy and fluorescence histochemistry. Gustatory (type III) cells occurred in the primitive taste buds during stage 1 (0-1 day after birth). These cells had an immature type of afferent synaptic contacts with nerve terminals; however, no specific fluorescence was found in the taste buds after administration of 5-HTP or L-DOPA. During stage 2 (2-7 days), mature types of afferent synapses, taste pores, type I cells and type II cells appeared in the taste buds, and fluorescent cells also appeared following treatment of 5-HTP or L-DOPA. During stage 3 (14-21 days), the gustatory cells underwent ultrastructural changes following injection of 5-HTP; i.e. small dense-cored vesicles (30-60 nm) appeared scattered throughout the cytoplasm and were found to intermingle with small clear vesicles accumulated at the presynaptic membranes of afferent synapses, and the electron densities of large dense-cored vesicles (80-100 nm) were elevated as compared with those of untreated mice. Consequently the ability of gustatory cells to take up amine-precursors started simultaneously with the formation of taste pores and mature afferent synapses between the gustatory cells and the sensory nerves.

5-Hydroxytryptophan↗
PubMed1978

Electron microscopic study of the snout muscle spindles of the mole following denervation.

The authors examined electron microscopically the daily effects of the muscle spindles of the mole snout muscles following unilateral facial neurotomy. The denervated muscle spindles show first a degenerative sign of the sensory end bulb 1 day after the operation and later a degenerative sign of the intrafusal muscle fibers one week after the operation. The muscle spindles on the untreated side show first a degenerative sign of the intrafusal muscle fibers 2 weeks after the operation and later a degenerative sign of the sensory end bulb 20 days after the operation. 40 to 90 days after the operation, the spindles on both sides show the same degenerative signs, the intrafusal muscle fibers having become much thinner than the control.

Animals↗
PubMed1977

Immunological and biochemical investigations on the fluorocarbon-treated antigens obtained from placenta and from cancer tissues.

Biochemical and immunological investigations were made on the nature of fluorocarbon-treated antigens obtained from placenta and cancer tissues. 1) By the diffusion in gel method, a specific antigen common to cancer tissues was found in placental tissue, but not in normal tissue. Immunoelectrophoretically, a characteristic precipitate line was found in alpha2-globulin region. 2) Further purification of the placental antigens was carried out by DEAE-cellulose chromatography. Four fractions positive to Folin reaction were detected. 3) Immunoelectrophoresis revealed that the active component was concentrated in a fraction eluted with 0.1 M NaCl in 0.05 M phosphate buffer, pH 5.8 (5.8-fraction). 4) Further purification of the active component was performed by using polyacrylamide gel electrophoresis. Chemical analysis indicated that it belonged to glycoprotein. 5) This substance did not induce anemia in rabbits and had no influence on the osmotic fragility of erythrocytes. These results indicate that this substance is different from the anemia-inducing substance which was previously reported by us.

Antigens, Neoplasm↗
PubMed1976

The fine structure of the outer capsule of the snout muscle spindle in the Japanese lesser shrew-mole.

The fine structure of the outer capsule of the snout muscle spindles of the Japanese lesser shrew-mole (42 spindles from 9 animals) was described electron microscopically. The capsule of the snout muscle spindle is composed of 5 to 6 layers of the so-called capsule cells derived from the perineural epithelium of the peripheral nerve which supplies the spindle. The capsule cells revealed the presence of numerous pinocytotic vesicles, granular endoplasmic reticulum, abundant ribosomes, mitochondria, dense bodies, microvesicles and Golgi complex. It would be highly suggestive of their secretory or transporting activity. The various types of plication within the capsule of the muscle spindle were detected in the equatorial region. By means of such projections the functioning surface of the outer capsule has been enormously increased.

Animals↗
PubMedDate not supplied

Effect of nordihydroguaiaretic acid on behavioral impairment and neuronal cell death after forebrain ischemia.

The purpose of this study was to evaluate the neuroprotective effect of nordihydroguaiaretic acid (NDGA), an antioxidant and/or 5-lipoxygenase inhibitor, on ischemia-reperfusion injury behavioral pharmacologically and histologically in vivo. First, the antioxidant activity of NDGA was evaluated in vitro by measuring the production of thiobarbituric acid reactive substances (TBARS) in rat brain homogenate. Second, the effect of NDGA on learning and memory impairment induced by rat four-vessel occlusion transient ischemia was investigated with the Morris water-maze task. Third, the effect of NDGA on pyramidal cell loss in the hippocampus after transient ischemia was examined. NDGA inhibited the production of TBARS with an IC(50) of 0.1 microM, and significantly attenuated postischemic learning and memory impairment at 10 mg/kg. Furthermore, consecutive 4-day administration of NDGA at 10 mg/kg significantly reduced the postischemic neuronal death. NDGA was found to be potent and effective as an anti-ischemia-reperfusion injury agent in terms of behavioral pharmacology and histology. The present results suggest that NDGA has beneficial effects on behavioral deficits and histological injury caused by ischemia-reperfusion.

Animals↗
PubMedDate not supplied

Facilitation of passive avoidance response by newly synthesized cationized arginine vasopressin fragment 4-9 in rats.

The effects of a newly synthesized cationized arginine vasopressin fragment 4-9 analogue (C-AVP-(4-9)) on learning and memory in rats were studied by the passive avoidance test. C-AVP-(4-9) and its parent peptide, arginine vasopressin fragment 4-9 (AVP-(4-9)), a well known potent neuropeptide, were subcutaneously injected 1.5 hr prior to the retention test. The most effective doses of C-AVP-(4-9) and AVP-(4-9) were 8.6 x 10(-2) and 1.3 nmol/kg, respectively. To evaluate the distribution of C-AVP-(4-9) in the control nervous system (CNS), apparent tissue-plasma concentration rations (Kp.app) of intravenously administered radioiodinated C-AVP-(4-9) (125I-C-AVP-(4-9)) in the CNS in mice were determined. At the apparent steady state of plasma concentration of 125I-C-AVP-(4-9), the Kp.app values of the 125I-C-AVP-(4-9) in the cerebrum, cerebellum and spinal cord were over 12 times higher than that of the vascular space marker which slightly penetrates the BBB. Moreover, the rat cerebral homogenate converted C-AVP-(4-9) into its parent peptide AVP-(4-9). These results suggest that the potent effects of C-AVP-(4-9) on learning and memory may be due to AVP-(4-9) generated as a result of distribution and metabolism of peripherally administered C-AVP-(4-9) in the CNS.

Animals↗