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H Arita

Publications and source records attributed to H Arita.

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

[Neural control of tracheal smooth muscle during cough].

Contraction of tracheal smooth muscle during mechanically induced coughing was studied in dogs. Recordings of smooth muscle tension were obtained from the cervical trachea, which is not influenced by intrathoracic pressure. We observed that during breathing at rest, tracheal smooth muscle contracts and relaxes in synchrony with phrenic nerve activity. When cough occurs, the tracheal smooth muscle contracts continuously and tonically with no rhythmic correlation to phrenic nerve activity. Sometimes the contraction starts before the phrenic nerve activity increases. A neuromuscular blocking agent caused a significant decrease in phrenic nerve activity in response to mechanical stimulation. The correlation between phrenic nerve activity and tracheal smooth muscle tension during normal breathing was also observed after afferent inputs from pulmonary mechanoreceptors were interrupted. During coughing, however, this correlation was lost. From these results we conclude that the neural control of tracheal smooth muscle is at least partially independent of phrenic nerve activity during coughing. Because coughing was attenuated by neuromuscular blocking agents, we speculate that there is a positive feedback mechanism from receptors in the chest wall or airway, which increases the magnitude of coughing.

Animals↗
PubMed1994

Structural comparison of phospholipase-A2-binding regions in phospholipase-A2 receptors from various mammals.

We determined the nucleotide sequence of a mouse cDNA encoding the receptor for pancreatic group I phospholipase A2 (PLA2-I). Interspecies structural comparison of the mouse receptor with bovine PLA2-I receptor, whose structure had been clarified, revealed that the fourth carbohydrate-recognition domain (CRD)-like domain (CRD-like 4) was the most conserved among the domains in the PLA2-I receptor, suggesting the functional importance of CRD-like 4. A transient expression experiment with a truncated form of the receptor consisting of three CRD-like domains, from the third to the fifth, demonstrated that the PLA2-I-binding site of the receptor is constituted from these three CRD-like domains, supporting the functional indispensability of CRD-like 4 in the receptor. Since the PLA2-I-binding region was thus assigned to be CRD-like domains 3-5, we further analyzed the structures of the PLA2-I-binding regions in the PLA2-I receptors from the rat, rabbit and human. Furthermore, the obtained PLA2-I receptor cDNA fragments from these animals made it possible to examine the tissue expression patterns of this receptor in various mammals. The results, together with the results of the genomic structural analysis of this gene, indicated that a PLA2 receptor recently characterized by Lambeau et al. [Lambeau, G., Ancian, P., Barhanin, J. & Lazdunski, M. (1994) J. Biol. Chem. 269, 1575-1578] is a rabbit counterpart of the PLA2-I receptor although these two PLA2 receptors have distinctive PLA2-binding specificities.

Amino Acid Sequence↗
PubMed1994

Generation of hiccup by electrical stimulation in medulla of cats.

The present study has revealed that a hiccup-like response (a brief powerful inspiratory activity accompanied by glottic adduction) can be generated by electrical stimulation to a limited area within the medullary reticular formation of the cat. This finding indicates that there is a neuronal network coordinating the hiccup reflex within the lower brain stem.

Animals↗
PubMed1994

Molecular cloning of pancreatic group I phospholipase A2 receptor.

We have recently reported that mammalian pancreatic group I phospholipase A2 (PLA2-I) has its specific receptor (PLA2 receptor) on a variety of mammalian cells and that various biological responses are elicited by PLA2-I via this receptor. In this study, we cloned cDNAs encoding a protein corresponding to the bovine PLA2 receptor purified from the corpora lutea on the basis of its partial amino acid sequences. The identity of a protein encoded by the cloned cDNA with the bovine PLA2 receptor was verified by a transient expression experiment using COS-7 cells. Interestingly, the deduced primary structure of the PLA2 receptor (1,463 amino acid residues) exhibits a close relatedness throughout the molecule to that of the macrophage mannose receptor, a unique member of Ca(2+)-dependent (C-type) animal lectin family, in spite of their functional diversity. Based on this sequence similarity between these two receptors, the domain organization of the PLA2 receptor could be tentatively assigned as follows; 10 extracellular domains including 8 tandem repeats homologous to C-type carbohydrate-recognition domains (CRDs) and a single transmembrane region followed by a short cytoplasmic tail. The results of transient expression experiments for mutant PLA2 receptors supported this assignment and furthermore suggested the region responsible for PLA2-I binding corresponds to CRDs in the mannose receptor.

Amino Acid Sequence↗
PubMed1994

Pancreatic-type phospholipase A2 induces group II phospholipase A2 expression and prostaglandin biosynthesis in rat mesangial cells.

The effect of pancreatic group I phospholipase A2 (PLA2-I) on receptor-mediated expression of arthritic group II phospholipase A2 (PLA2-II) and its correlation with prostaglandin E2 (PGE2) synthesis were examined in cultured rat mesangial cells. Scatchard analysis using 125I-PLA2-I revealed the existence of a single class of specific binding sites for PLA2-I in rat mesangial cells with an equilibrium dissociation constant (Kd) of 1.6 nM and a maximum binding capacity of 10.1 fmol/10(6) cells. The mammalian mature type of PLA2-I specifically recognized this binding site, whereas its inactive zymogen and mammalian PLA2-II showed much lower affinities. PLA2-I markedly increased PLA2-II mRNA levels as well as PLA2-II secretion from the cells in a time- and dose-dependent manner that was closely correlated with PGE2 production. Both PLA2-II expression and PGE2 synthesis were completely suppressed by pretreatment of the cells with actinomycin D, cycloheximide, or dexamethasone. These results strongly suggest that there may be crosstalk between PLA2-I and PLA2-II via the specific PLA2-I receptor that elicits PGE2 synthesis.

Animals↗
PubMed1994

Plasmin converts pro-form of group I phospholipase A2 into receptor binding, active forms.

Treatment of zymogen of pancreatic-type group I phospholipase A2 (PLA2-I) by plasmin, a fibrinolytic enzyme, increases PLA2 activity as well as receptor binding activity in a dose- and time-dependent manner. Separation of plasmin-treated pro-PLA2-I by HPLC and amino acid sequence analysis of the products revealed that, in addition to an authentic mature PLA2-I produced by trypsin, plasmin produced active products which had been modified in the C-terminal region. Thus, PLA2-I may be involved in physiologic processes which accompany the formation of plasmin.

Amino Acid Sequence↗
PubMed1994

Comparative study of inhibitory effects by murine interferon gamma and a new bisphosphonate (alendronate) in hypercalcemic, nude mice bearing human tumor (LJC-1-JCK).

The inhibitory effect of murine interferon gamma (muIFN gamma) on humoral hypercalcemia in nude mice bearing lower-jaw cancer (LJC-1-JCK), in which parathyroid-hormone(PTH)-related protein is responsible for causing humoral hypercalcemia by activating bone resorption, was examined in comparison with that of a new bisphosphonate, 4-amino-1-hydroxybutylidene-1,1-bisphosphonate (alendronate). muIFN gamma was injected into tumor-bearing nude mice for 5 days before the establishment of hypercalcemia. The increase of plasma calcium concentration was delayed and this effect continued for more than 6 days even after the injection was stopped. Alendronate markedly suppressed hypercalcemia in tumor-bearing nude mice but this inhibitory effect continued for less than 6 days. Neither muIFN gamma nor alendronate affected the tumor volume or serum PTH-related protein concentration. Injection of muIFN gamma into mice for 3 days almost completely abolished the formation of multinucleated osteoclast-like cells from bone marrow cells in vitro, whereas injection of alendronate into mice had no effect. These findings suggested that muIFN gamma suppressed the formation of osteoclasts, resulting in the prolonged decrease of plasma calcium concentration in hypercalcemic tumor-bearing nude mice, whereas alendronate is cytotoxic to functionally mature osteoclasts and inhibited osteoclastic bone resorption, resulting in a marked decrease in the plasma calcium concentration in tumor-bearing hypercalcemic nude mice.

Adult↗
PubMed1994

Adrenergic cell group in rostral ventrolateral medulla of cat: its correlation with central chemoreceptors.

We have proposed a hypothesis that secondary neurons mediating central respiratory chemoreception are not restricted to the medullary superficial layer. This idea was further examined in the present physiological and morphological studies. We identified the 'S' area, i.e. the medullary surface area where cold blockade produced apnea, in anesthetized, spontaneously breathing cat. We then evaluated how the apnea was modified by injection of CO2-saturated saline into the vertebral-basilar artery. The CO2 injection caused immediate reappearance of respiratory rhythm, although intensity of inspiratory activity was smaller than in the control. This incomplete recovery suggests that the responsive structure extends deeply below the surface. The extent of the cell group underlying the 'S' area was evaluated by morphological study. Medullary transverse sections including the 'S' area were treated with three distinct antisera against phenylethanolamine N-methyltransferase (PNMT), dopamine-beta-hydroxylase (DBH), and 5-hydroxytryptamine (5-HT). The PNMT-labelled cell group was found to exactly underlie the 'S' area, although the DBH- and the 5-HT-labelled cell groups did not show close topographic correlation with the 'S' area. PNMT cells were located in the region ventral to retrofacial nucleus within 0.5-1.5 mm depth beneath the surface. These results suggest that adrenergic cells in the rostral ventrolateral medulla are important candidates for secondary neurons mediating central respiratory chemoreception.

Animals↗
PubMed1994

Hiccuplike response elicited by mechanical stimulation of dorsal epipharynx of cats.

To identify the site for triggering hiccup, we recorded activities from the diaphragm (DIA), posterior cricoarytenoid muscle (PCA) of the larynx, and abdominal muscle (ABD) along with intrapleural pressure (Ppl) in anesthetized spontaneously breathing cats. To directly access the epipharynx and to observe glottic movement, we made a submental opening at the level rostral to the epiglottis. Mechanical stimulation of the epipharynx evoked a fixed motor pattern of hiccup: DIA showed spasmodic discharge, and Ppl exhibited spiky negative pressure swing; phasic (inspiratory) discharge of PCA was inhibited, and glottic adduction was revealed by direct observation; and ABD remained suppressed during this response. Chlorpromazine hydrochloride or CO2 inhalation suppressed the response, and the intensity of the response varied according to phase of the respiratory cycle, being largest at midinspiration and least at midexpiration. These are compatible with clinical data on human hiccup. Mechanical stimulation of various parts other than the epipharynx failed to evoke the hiccuplike response. The triggering site was located in the dorsal wall of the epipharynx overlying the occipital bone. These results indicate that mechanical irritation of the dorsal epipharynx is essential for triggering hiccup.

Animals↗
PubMed1994

Gene expression of pancreatic-type phospholipase-A2 in rat ovaries: stimulatory action on progesterone release.

We reported previously that pancreatic-type group I phospholipase-A2 (PLA2-I) stimulates DNA synthesis or prostaglandin E2 production in various cell types via its specific receptors on the cell surface. In the present study we examined the effect of PLA2-I on corpus luteum, which possesses specific PLA2-I receptors, and demonstrated gene expression of PLA2-I in rat ovaries. PLA2-I stimulated progesterone release from incubated corpora lutea at concentrations above 10 nM in a dose-dependent manner. Northern blot analysis revealed the presence of PLA2-I messenger RNA (mRNA) in rat ovaries. The level of PLA2-I mRNA was elevated during diestrus to proestrus, and decreased to almost nothing on the day of estrus. To further evaluate the timing of PLA2-I expression, we analyzed RNAs extracted from small follicles, large preovulatory follicles, and corpora lutea obtained from various phases of hCG-treated immature rats. During follicular development, mRNA levels remained negligible. The level of PLA2-I mRNA began to rise after luteinization of follicles and increased during the maturation of the corpora lutea. Levels of PLA2-I mRNA in ovaries from day 5 and day 10 pregnant rats were 5- to 10-fold higher than those in diestrous rats, whereas on day 21, the mRNA level was decreased. Immunocytochemical studies were performed to clarify the synthesis and localization of PLA2-I in the ovary using polyclonal anti-PLA2-I antibodies. Intense immunoreactivity was detected only in luteal cells of newly formed corpora lutea. However, the number and intensity of immunoreactive cells decreased in old corpora lutea. No immunoreactivity was detected in follicular cells of small- or middle-sized follicles. These results demonstrate the correlation among PLA2-I gene expression, estrous cycle, and progesterone secretion in rat ovaries and suggest a new function of PLA2-I as an intragonadal regulatory factor for steroidogenesis.

Animals↗
PubMed1994

[Preexisting seizure was enhanced under general anesthesia in a AVM patient].

A 21-year-old patient with right basal ganglial AVM was scheduled twice for cranioplasty under general anesthesia (nitrous oxide oxygen isoflurane anesthesia and modified neurolept anesthesia), after a surgery for removal of hematoma from the AVM three months previously. After this operation and before anesthesia for cranioplasties, he showed tremor-like seizure around the left arm and leg about once a day. During anesthesia for cranioplasties, he developed the similar and enhanced seizure frequently in response to intravenous injections of thiopental and midazolam, needle injections into the skin, intratracheal as well as oral suctions and other stimuli. The reason of decreased cerebral perfusion is probably due to the previous operation and administrations of thiopental and midazolam. Because of decreased perfusion around this cerebral lesion, concentrations of the anesthetics might have remained low around the lesion under general anesthesia. Therefore, the resulting hypoxia and prolonged light anesthesia in the basal ganglia, might have enhanced the seizure.

Adult↗
PubMed1994

[Anesthesia in a patient with Scheie syndrome].

Mucopolysaccharidosis (MPS) is a rare metabolic disease characterized by abnormal accumulation and excretion of mucopolysaccharides. Patients with MPS have many anesthetic problems including ischemic heart disease, valve insufficiency, difficult intubation, joint stiffness and mental retardation. We report a case of Scheie syndrome, a mild type of MPS, which presented a unique problem of difficult intubation. The patient was a 35 year old woman, scheduled for anterior fixation of the 4th lumbar vertebra. Her manifestations included low height, corneal clouding and systemic joint stiffness. Coronary artery disease was suspected from ECG. There was no mental retardation. Mouth opening was possible for about 4.5 cm. After induction with fentanyl, thiopental and vecuronium, intubation under laryngoscopy was tried but impossible because mouth opening was restricted to only 2 cm. Therefore muscle relaxant was reversed with neostigmine and atropine. Then under spontaneous respiration, she was intubated using a bronchofiberscope. It is difficult to explain why her mouth opening was more restricted after induction. We suspect mechanical change of temporomandibular joint or low compliance of the muscles. In conclusion, as reported previously, spontaneous respiration should be maintained until intubation. Especially in a patient with Scheie syndrome, whose mental development is normal, fiberoptic intubation should prove to be useful.

Adult↗
PubMed1993

Receptor-binding capability of pancreatic phospholipase A2 is separable from its enzymatic activity.

Mammalian pancreatic phospholipase A2 (PLA2-I) has its specific receptor through which PLA2-I induces a variety of biological responses. In this study, a fundamental relationship between the enzymatic and the receptor-binding activities of PLA2-I was investigated. The specific binding of PLA2-I to the receptor was found to be independent of Ca2+ which is requisite for the PLA2 activity. On the basis of this observation, we designed and produced mutant PLA2-Is without Ca(2+)-binding abilities in order to demonstrate that the structural requirement for the enzymatic activity of PLA2-I is not identical with that for its receptor-binding reaction. These mutant PLA2-Is lost almost all enzymatic activity through a disturbance at the Ca(2+)-binding site, as expected, but still retained a substantial affinity to the receptor, allowing us to conclude that the receptor-binding reaction of PLA2-I is separable from its catalytic action.

Animals↗
PubMed1993

Pancreatic-type phospholipase A2 stimulates prostaglandin synthesis in mouse osteoblastic cells (MC3T3-E1) via a specific binding site.

Previously, we have reported a novel proliferative action of pancreatic group I phospholipase A2 (PLA2-I) via a specific binding site in Swiss 3T3 fibroblasts, vascular smooth muscle cells, and chondrocytes. In this study, we characterized the PLA2-I specific binding site in osteoblastic cell line (MC3T3-E1 cells) with an equilibrium binding constant (Kd) value of 1.13 nM and maximum binding capacity of 40.1 fmol/10(6) cells. PLA2-I stimulated prostaglandin E2 (PGE2) production in a concentration-dependent manner in MC3T3-E1 cells, and its EC50 value was similar to the Kd value for PLA2-I binding. This effect of PLA2-I was type-specific and did not depend on its hydrolytic activity. PLA2-I increased the activity of prostaglandin endoperoxide synthase (PES), and PLA2-I-stimulated PGE2 synthesis was inhibited by cycloheximide. Northern blot analysis showed the increase in both type-1 and type-2 PES mRNAs. These findings indicated that PLA2-I stimulated PGE2 synthesis by induction of PES via a specific binding site in osteoblastic cells.

3T3 Cells↗
PubMed1993

Serotonin innervation patterns differ among the various medullary motoneuronal groups involved in upper airway control.

The purpose of this study was to test our hypothesis that the serotoninergic system plays a significant role in airway obstruction during sleep, by focusing on patterns of serotoninergic innervation of the medullary motoneurons involved in upper airway control. We used the combined techniques of retrograde labelling of motoneurons with unconjugated cholera toxin B and immunohistochemistry with antiserum against serotonin (5-HT). The retrograde tracers were injected into posterior cricoarytenoid (PCA), cricothyroid (CT), and genioglossal (GG) muscles of the cat. Motoneurons retrogradely labelled from PCA were identified ipsilateral to the injection site in the caudal part of nucleus ambiguus (NA). Serotonin immunoreactive terminals surrounded their somata and proximal dendrites, suggesting a strong influence of serotonin on the PCA-labelled motoneurons. Motoneurons retrogradely labelled from CT were located ipsilaterally in two distinct groups in the rostral NA and in the retrofacial nucleus (RFN). Selective peripheral nerve section revealed that the CT-labelled motoneurons in the NA had axons in the recurrent laryngeal nerve, whereas the other CT-labelled motoneurons in the RFN were innervated through the superior laryngeal nerve. In the RFN, the pattern of 5-HT innervation in relation to the CT-labelled motoneurons was analogous to that observed with the PCA-labelled motoneurons. In the NA, however, 5-HT terminals made few contacts with the CT-labelled motoneurons, although a dense network of 5-HT terminals was present in the surrounding region. In the GG-labelled motoneuron region of the hypoglossal nucleus, 5-HT terminals were apposed to distal dendrites, not to the soma, indicating less effect of serotonin on GG than on PCA activity. The present results demonstrated that the patterns of 5-HT innervation vary according to the type of motoneurons and their projections to the upper airway.

Animals↗