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Biomedical subjects

M Hirano

Publications and source records attributed to M Hirano.

At least 289 records · Page 16Linked to original sources
PubMed1995

A study on thapsigargin-induced calcium ion and cation influx pathways in vascular endothelial cells.

To investigate Ca2+/cation entry pathway in vascular endothelial cells, we examined the effects of thapsigargin on [Ca2+]i and Mn2+ entry in cultured porcine aortic endothelial cells. Thapsigargin inhibits the activity of endoplasmic reticulum (ER, intracellular Ca2+ pool) Ca(2+)-ATPase, and stimulates Ca2+ entry from extracellular space by depleting intracellular Ca2+ pool. Cultured endothelial cells were loaded with fura-2/AM, and [Ca2+]i was measured by the ratios of fluorescence at 340/380 nm excitation, and Mn2+ entry was observed by the quenching of fluorescence at 360 nm excitation. Thapsigargin elevated [Ca2+]i in a time- and dose-dependent manner. The increase in [Ca2+]i caused by thapsigargin was lowered in Ca(2+)-free solution containing 3 mM EGTA. Verapamil (10(-5) M) and equimolar replacement of extracellular NaCl by LiCl had no effects on the maximum elevation of [Ca2+]i by thapsigargin. The increase in [Ca2+]i by thapsigargin was significantly inhibited by either NiCl2 (10(-3) M) or membrane depolarization using 50 mM KCl. Thapsigargin stimulated Mn2+ entry concomitantly with the increase in [Ca2+]i. Mn2+ entry was augmented in Ca(2+)-free solution. These results suggested that (1) the increase in [Ca2+]i by thapsigargin consisted of both Ca2+ release from ER and Ca2+ entry from extracellular space, and (2) thapsigargin also stimulated Mn2+ entry, which was interfered with in the presence of extracellular Ca2+.

Animals↗
PubMed1995

The effect of phencyclidine on the basal and high potassium evoked extracellular GABA levels in the striatum of freely-moving rats: an in vivo microdialysis study.

The effect of phencyclidine (PCP) on the gamma-aminobutyric acid-ergic (GABAergic) transmission in the striatum of freely-moving rats was investigated using an in vivo microdialysis. The high potassium (100 mM) increased the extracellular GABA level to 4000% of the basal level. Although the basal GABA level in the striatal dialysate did not show either calcium dependency or tetrodotoxin (TTX) sensitivity, the high potassium evoked GABA level was reduced by 82% under calcium-free conditions (with 12.5 mM magnesium) and by 54% in the presence of 10 microM TTX. The systemic administration of PCP (7.5 mg/kg) or the local perfusion of PCP (100 microM and 1 mM) significantly inhibited the high potassium evoked GABA release in the rat striatum. The local perfusion of MK-801 (10 microM and 100 microM), a more potent and selective N-methyl-D-aspartate (NMDA) receptor antagonist, also inhibited the high potassium evoked striatal GABA release. These drugs did not show any significant effect on the basal extracellular GABA level. NMDA (1 mM) either partly or completely blocked the effect of PCP (1 mM) or MK-801 (100 microM) on the high potassium evoked striatal GABA release. On the other hand, nomifensine (100 microM), a dopamine uptake blocker, did not show any effect on the high potassium evoked GABA release. These results suggest that PCP inhibited the striatal GABAergic neuronal transmission through its antagonism of the NMDA receptor.

Animals↗
PubMed1995

A protein kinase C isozyme, nPKC epsilon, is involved in the activation of NF-kappa B by 12-O-tetradecanoylphorbol-13-acetate (TPA) in rat 3Y1 fibroblasts.

In order to examine whether PKC is involved in the activation of NF-kappa B by TPA, we overexpressed a variety of PKC isozymes in rat 3Y1 fibroblasts and monitored the expression of the co-transfected reporter NF-kappa B gene. In contrast to TPA response element (TRE), where overexpression of a variety of PKC isozymes results in enhanced activation by TPA, activation of NF-kappa B by TPA is not enhanced by overexpression of PKC isozymes such as cPKC alpha, nPKC delta, or nPKC theta. However, the overexpression of nPKC epsilon does result in enhancement. A kinase-negative point mutant of nPKC epsilon, where Lys at the ATP binding site is altered to Arg, does not cause this enhancement of NF-kappa B activation. Further, the kinase-negative nPKC epsilon partially suppresses endogenous NF-kappa B activity. These results suggest that nPKC epsilon is specifically involved in the activation of NF-kappa B when cells are treated with TPA.

Animals↗
PubMed1995

Epidermal growth factor enhances repair of rat intestinal mucosa damaged by oral administration of methotrexate.

To examine the trophic effect of epidermal growth factor on the rat small intestine, we measured diamine oxidase and ornithine decarboxylase activities in intestinal mucosa injured by methotrexate. Methotrexate was infused orally via a gastric tube at a dose of 10 mg/kg per day on 3 successive days (days 1-3). Epidermal growth factor was injected intraperitoneally at a dose of 40 micrograms/kg per day on 4 successive days following methotrexate infusion (days 4-7). Methotrexate caused a marked decrease in diamine oxidase activity; this decrease returned to a normal level on day 13 in controls. In rats injected with epidermal growth factor, diamine oxidase activity began to recover earlier than in the controls, and returned to a normal level on day 11. Epidermal growth factor enhanced the increase of ornithine decarboxylase activity in mucosa injured by methotrexate. When the increase of ornithine decarboxylase activity was suppressed by alpha-difluoromethylornithine, epidermal growth factor failed to facilitate the repair of intestinal mucosa. These results indicate that epidermal growth factor enhances intestinal repair following methotrexate infusion, and that this effect is mediated, at least in part, by ornithine decarboxylase. It is proposed that epidermal growth factor can be used clinically as a means to enhance mucosal repair of the intestine after chemotherapy with methotrexate.

Administration, Oral↗
PubMed1995

Phosphatidylinositol responses are involved in the vascular effects of thiamylal and fentanyl.

Although thiobarbiturates potentiate, and fentanyl attenuates peripheral vasoconstriction, the intracellular mechanism involved in this phenomenon is not clear. Because smooth muscle contraction induced by alpha 1-adrenoceptor agonists is mediated by the phosphatidylinositol (PI) response, this study was carried out to clarify if thiamylal and fentanyl affect the norepinephrine-induced PI response in rat aortic slices. Rat aortic slices were incubated in Krebs-Henseleit solution containing 5 mM LiCl, [3H]myo-inositol, and varying concentrations of thiamylal or fentanyl. The Pl response was stimulated by 0.9 microM (ED50) norepinephrine (NE). The [3H]inositol monophosphate (IP1) was separated from [3H]myo-inositol by column chromatography and counted with a liquid scintillation counter. The basal IP1 accumulation was not affected by thiamylal and fentanyl. Norepinephrine-induced IP1 accumulation was potentiated by thiamylal at concentrations of 10 microM and 100 microM. Norepinephrine-induced IP1 accumulation was attenuated by 1 microM and 10 microM fentanyl. The results suggest that thiamylal stimulates the NE-induced PI response, which potentiates the vasoconstriction, and fentanyl attenuates NE-induced PI response, which would attenuate the vasoconstriction.

Anesthetics, Intravenous↗
PubMed1995

Osteogenesis in muscle with composite graft of hydroxyapatite and autogenous calvarial periosteum: a preliminary report.

To investigate the bone forming activity of composite grafts of hydroxyapatite (HA) and autogenous calvarial periosteum, porous HA rods with or without the periosteum were implanted into the back muscle of white rabbits. They were harvested 3 and 6 months after implantation and studied histologically and microradiographically. Bone formation in the pores of HA occurred in three out of four composite implants of the 3 month group, and four out of five implants of the 6 month group. The two specimens without bone formation revealed irregular calcified tissue outside the HA implant. No formation of bone and calcified tissue took place in any of the specimens with HA alone. These results indicate the potential of this new experimental system of ectopic osteogenesis and offer the possibility of a new improved bone graft consisting of HA and autogenous periosteum.

Animals↗
PubMed1995

Voice disorders in children.

The pediatric otolaryngologist has an especially important role in the differential diagnosis and treatment of two voice disorders; these are the voice quality problems (dysphony) and the resonance problems (rhinophony). The first step in the examination is to preclude the organic causes. The functional dysphonia is mostly related to voice abuse/misuse, but may be present on a psychosomatic basis; environmental factors can also play a role in the etiology and the personality structure has been found to be very relevant. The perceptual evaluation of voice is of obvious importance. Endoscopy with a transnasal flexible scope makes it possible, in practically all cases, to identify the morphodynamic changes. Stroboscopy and phonetography can be carried out only in older children, sometimes a 'trial treatment' is of valuable help. The therapy can be divided into five groups (counselling, voice re-education, drug treatment, psychotherapy, surgery), but should be always individual. An open question: how to choose the preferable treatment of vocal nodules: surgery, conservative or wait-and-see? According to a detailed survey in Kurume University Hospital the following can be stated: if the patient is in trouble due to hoarseness, and immediate improvement of his voice is necessary, surgery should be indicated; if they need the improvement but do not need it urgently, voice therapy is recommended; without motivation vocal hygiene is proposed. No matter what treatment patients receive, their voices improve in the majority after puberty, but 15% of the patients do not show any improvement. In cases of hoarseness due to long-term postintubational glottic lesions logopedic treatment is the only therapeutic possibility. The delay of speech development of tracheotomized children can and should be avoided by applying proper cannula technique and by logopedic training. The physiological nasality which depends upon the undisturbed activity of the velopharyngeal closure, can become pathologic in four forms: closed, open, mixed and alternating nasality (rhinophonolalia). In the diagnosis of hyperrhinophony due to VPI X-ray procedures, supplemented with nasendoscopy, proved to be the most informative methods, the etiology (neuromyogen processes) may be revealed by electrophysiological methods; the voice and speech can be assessed and visualized by nasometry, but the detailed speech evaluation is indispensable. The basic possibilities of treatment are as follows: speech therapy, surgery, speech bulb, electrotherapy and medicines. The basis of operative treatment is flap surgery. The anatomical result of 1000 (velo) pharyngoplasties carried out in Madarász and Heim Pál Children's Hospital (Budapest) is good in 98%, the hyperrhinophony ceased or became minimal in 90% after surgery. The ideal age for operation is 4.5 years.

Adolescent↗
PubMed1995

Precise localization of VIP-, NPY-, and TH-immunoreactivities of cat laryngeal glands.

The precise distribution of vasoactive intestinal polypeptide (VIP)-, neuropeptide Y (NPY)-, and tyrosine hydroxylase (TH)-immunoreactive (ir) fibers in the cat's laryngeal glands was examined by immunoelectronmicroscopy. A relatively dense population of VIP-ir fibers was recognized close to the basal lamina of the glandular and myoepithelial cells. Some VIP-ir fibers contacted with the basal lamina and some of them pierced it and ran intercellularly in the adjoining glandular cells without making synaptic contacts with them. NPY- and TH-ir fibers were located in the vicinity of the basal lamina, but they were less abundant than VIP-ir fibers at this region. They never terminated or penetrated the basal lamina. Pattern of distribution of TH-ir fibers was similar to that of NPY-ir fibers. The estimated ratio of VIP-, TH-, and NPY-ir fibers was 20:4:1 from the density of fibers in the laryngeal glands. This value was equal between serous and mucous glandular cells, so both types of glandular cells may receive the same pattern of autonomic innervation.

Animals↗
PubMed1995

Early-onset respiratory syncytial virus pneumonia after allogeneic bone marrow transplantation.

A 41-year-old woman with follicular lymphoma developed sporadic respiratory syncytial virus (RSV) pneumonia shortly after allogeneic bone marrow transplantation from an HLA-matched sibling. RSV pneumonia is potentially fatal in immunosuppressed patients, but she improved along with the recovery of bone marrow function without specific treatment. Early recovery of myelosuppression supported by granulocyte colony-stimulating factor may have helped to control RSV pneumonia.

Adult↗
PubMed1995

Expression of Fos-protein activated by tactile stimulation on the laryngeal vestibulum in the cat's lower brain stem.

To demonstrate morphologically the neurons participating in the laryngeal reflex, Fos-expression, activated with tactile stimulation of the laryngeal vestibulum, was mapped in the cat's lower brain stem utilizing immunohistochemistry. In the stimulation group, many Fos-immunoreactive (ir) neurons were recognized in the nucleus tractus solitarii (NTS) from the level of the most rostral portion of the dorsal motor nucleus of the vagus to the level of the most caudal portion of the inferior olivary nucleus (IO), and in the nucleus ambiguus (NA) from the level of the rostral end of the hypoglossal nucleus to the level of the caudal end of the IO, bilaterally. While some Fos-ir cells were found in the spinal nucleus of the trigeminus, they were also found in the reticular nuclei bilaterally. In the control group, Fos-ir cells were distinctly fewer in number than those in the stimulation group. The results suggested that in the brain stem, the laryngeal reflex pathways have more than two synaptic relays through the interneurons in between the NTS and the NA.

Animals↗
PubMed1995

Arrangement and number of intralaryngeal ganglia and ganglionic neurons: comparative study of five species of mammals.

The arrangement and number of intralaryngeal ganglia and their neurons in five mammals (dog, rat, guinea pig, rabbit and cat) were examined morphologically. Intralaryngeal ganglions were situated mainly in branches of the internal branch of superior laryngeal nerve (Int-SLN), dorsal and/or dorsolateral to the posterior cricoarytenoid muscle, and around the inferior laryngeal nerve in dogs, rats, guinea pigs and cats, but they were identified at the branching out point of the Int-SLN exclusively in rabbits. The ganglion of each animal was spindle-shaped, with a surrounding fibrous capsule, and it contained many ganglionic neurons, vessels and connective tissue cells. The ganglionic neuron was oval-shaped and had a round nucleus: the diameter was smaller (20-25 microns) in the rat than in the other mammals (25-30 microns). More than 80 per cent of ganglionic neurons occurred in the supraglottis of all the animals except the rat. In the rat, this value was approximately 40 per cent.

Animals↗
PubMed1995

A comparison of coronary hemodynamics during isoflurane and sevoflurane anesthesia in dogs.

We studied the effects of sevoflurane and isoflurane on coronary hemodynamics in relation to myocardial oxygen supply and demand. Dogs were anesthetized with pentobarbital and fentanyl and received isoflurane or sevoflurane. An electromagnetic flow probe and a pair of piezoelectric crystals were placed on the left circumflex coronary artery (CX) to measure CX flow and diameter. The dogs were randomly assigned to receive isoflurane or sevoflurane at a dose of 0.75 and 1.5 minimum alveolar anesthetic concentration (MAC). The CX diameter decreased in parallel with the decrease in mean arterial pressure during both anesthetics. The CX blood flow decreased in parallel with the decrease in myocardial oxygen consumption (MVo2) during sevoflurane, whereas it did not change in spite of the decrease in MVO2 during isoflurane. The CX vascular resistance decreased significantly during isoflurane but not during sevoflurane. Moreover, the myocardial oxygen extraction ratio (Mo2exr) decreased at 0.75 and 1.5 MAC isoflurane and at 1.5 MAC sevoflurane, and the decrease in Mo2exr was significantly greater during isoflurane than during sevoflurane. The results suggest that sevoflurane is a less potent coronary arteriolar dilator than isoflurane, and that neither sevoflurane or isoflurane has a direct effect on the diameter of large coronary arteries.

Anesthesia↗
PubMed1995

Involvement of dopamine D1 receptors in phencyclidine-induced behavioral stimulation in rats.

The effects of dopamine receptor antagonists on phencyclidine (PCP)-induced behaviors were examined in rats. Acute administration with PCP (7.5 mg/kg i.p.) produced various behavioral changes, such as increases of spontaneous activity, head-weaving, sniffing, rearing, back-pedaling, and ataxia. To determine which dopamine receptor subtypes were involved in mediating the PCP-induced behaviors, SCH 23390 (0.05 and 0.5 mg/kg), sulpiride (20 and 100 mg/kg), or haloperidol (0.05 and 0.5 mg/kg) were pretreated 30 min before PCP treatment (7.5 mg/kg). A higher dose of SCH 23390 significantly reduced the increase of spontaneous activity induced by PCP. Both doses of sulpiride did not affect the PCP-induced behaviors. A higher dose of haloperidol decreased the PCP-induced spontaneous activity, whereas a lower dose of haloperidol enhanced the activity. Ketanserin (0.5 and 5 mg/kg) did not alter any PCP-induced behaviors. These results suggest that the D1, but not D2, dopamine receptor subtype may be involved in the PCP-induced behavioral abnormality.

Animals↗
PubMed1995

Snake-strike--induced ischemic colitis with colonic stricture complicated by disseminated intravascular coagulation.

A 57-year-old farmer was struck on the right thumb by a pit viper (Agkistrodon blomhoffü). Subsequently, he had acute renal failure and disseminated intravascular coagulation (DIC), associated with melanotic stools and abdominal pain. Renal failure caused by renal cortical necrosis was successfully treated with hemodialysis. A double-contrast barium enema examination revealed multiple stenoses of the colon, regional edema, and longitudinal ulcer. Histologic examination of the stenotic lesions after laparotomy revealed fibrosis of both submucosa and proper muscle layer, with fibrotic thickness in the small arteries of the colonic wall, indicating that ischemic colitis was associated with DIC. In this case, DIC from viper toxins played an etiologic role in the development of ischemic colitis with stricture, as well as acute renal failure.

Acute Kidney Injury↗
PubMed1995

Endothall thioanhydride inhibits protein phosphatases-1 and -2A in vivo.

The objective of this study was to relate the toxicity of several cantharidin-derivative pesticides with their abilities to inhibit protein phosphatases-1 (PP1) and -2A (PP2A). Cantharidin (CA), endothall, and endothall thioanhydride (ETA) inhibited the activity of PP1 and PP2A, and the potency sequence was CA > endothall > ETA in vitro. We determined the inhibitory potency of these pesticides on hepatic protein phosphatases by administration of the toxins into the portal vein of rats. The potency sequence of ETA > CA > endothall was established for the inhibition of PP1 and PP2A in vivo and shows close correlation with the sequence of relative toxicity. ETA predominantly targets PP1 for inhibition in liver, as revealed by assays specific for PP1 or PP2A. Studies using 3T3 fibroblasts showed that only ETA, but not CA or endothall, induced marked morphological changes. These effects included cell rounding and detachment as well as extensive reorganization of actin filaments and are characteristic for the cell-permeable phosphatase-inhibitory toxins. It is suggested that the in vivo effectiveness is related to enhanced uptake of ETA, because this is permeable across the plasmalemma.

Animals↗