Biomedical subjects

T Ohnuki

Publications and source records attributed to T Ohnuki.

At least 73 records · Page 4Linked to original sources

PubMed1995

Increased platelet aggregability in patients with vertigo, sudden deafness and facial palsy.

Many patients suffering from episodic vertigo have no cochlear symptoms. These patients have so far been diagnosed as having Meniere's disease of the vestibular type. However, the underlying mechanisms are still to be established. In the present study, we investigated platelet aggregability in patients with dizziness, Meniere's disease, sudden deafness and facial palsy, to examine whether abnormalities in platelet aggregation is one of the causes of episodic vertigo. In 36 patients with dizziness, in 13 with Meniere's disease, in 7 sudden deafness, and in 7 facial palsy, platelet aggregability to adenosine diphosphate (ADP) was assessed by optometric technique. It was found that platelet aggregability was increased in the patients with dizziness as well as with Meniere's disease, sudden deafness and facial palsy and only the two former patient groups showed a tendency of hyperlipidemia. The administration of antiplatelet and lipidemia drugs resulted in no recurrence of vertigo during at least 3 months' follow-up. Hence, the results of our study suggest that a possible initializing factor of vertigo without cochlear symptoms might be disturbed microcirculation due to platelet hyperaggregability.

Adolescent↗

PubMed1994

[Conservative treatment of postoperative chylothorax in a patient with chronic traumatic aneurysm of thoracic aorta].

A 66-year-old male was admitted to our hospital because of a chronic traumatic aneurysm of the thoracic aorta caused by a traffic accident 5 years earlier. Although he had been treated successfully by patch closure under extracorporeal circulation, chylothorax gradually manifested 9 days after the operation. The fact that our conservative treatment resulted in complete recovery from chylothorax, strongly suggested that progress of nutriology was a contributing factor.

Aged↗

PubMed1993

Characterization of a cloned rat serotonin 5-HT1A receptor expressed in the HeLa cell line.

We have previously isolated the rat serotonin (5-HT)1A receptor gene (G21Y2) and now report the expression and characterization of this receptor. The BamHI/Xbal fragment of this gene was cloned into Rc/RSV and stably transfected into HeLa cells by the calcium phosphate method. For determination of specific 5-HT1A receptor binding, [3H]8OH-DPAT was used as the radioligand and incubated with HeLa cell membranes. The cells expressed specific and saturable binding of [3H]8OH-DPAT with a Kd value of 0.3 nM and a Bmax value of 2 pmol/mg protein. GTP (50 microM) added to the incubation mixture increased the Kd value to 3 nM indicating that the expressed receptor is coupled to a G protein. The specific binding was inhibited by selective 5-HT1A partial agonists, such as buspirone, ipsapirone, gepirone, tandospirone, zalospirone and SUN8399 with Ki values of 1-30nM, whereas other neurotropic drugs except for spiperone (Ki = 46 nM) and nemonapride (Ki = 2.3 nM) were effective only at concentrations of more than 100 microM. The potencies of these compounds to inhibit [3H]8OH-DPAT from its specific binding sites were similar to their affinities determined in rat hippocampus binding studies. These data suggest that the expressed receptor is a 5-HT1A-type similar to 5-HT1A receptors in the rat hippocampus.

8-Hydroxy-2-(di-n-propylamino)tetralin↗

PubMed1993

Assessment of the chemical form of gaseous 35S species produced during the production of H3(32)PO4.

The chemical form of gaseous 35S species produced during the production of H3(32)PO4 was characterized in order to reduce 35S discharge by understanding its production mechanism and chemical reactivity. An air sample was evacuated from the cell in which the H3(32)PO4 production was being carried out and collected in a sample gas reservoir. Gaseous sulfur species contained in the sample were condensed in a cold trap maintained at -180 degrees C and analyzed by means of gas chromatography using a flame photometric detector. Sulfur dioxide (SO2) was the only sulfur species detected. Equilibrium constant calculations showed that SO2 would be expected to be the predominant species produced by reactions of sulfur molecules (Sn:n = 2-8) with oxygen in air and that the quantity of SO2 produced would be reduced by heating the irradiated sulfur target under vacuum or in atmospheres of inert gases.

Chromatography, Gas↗

PubMed1993

Cloning and characterization of a nitrite reductase gene from Alcaligenes faecalis and its expression in Escherichia coli.

The gene (nir) encoding the copper-containing nitrite reductase (NIR) of a denitrifying bacterium, Alcaligenes faecalis S-6, was cloned by a synthetic oligonucleotide-probing method. The nucleotide sequence of the cloned DNA fragment revealed the primary structure of the NIR precursor containing the N-terminal signal sequence for secretion. A nucleotide sequence, possibly recognized by a transcriptional regulator resembling FNR was found upstream of the structural gene. When the cloned gene was expressed in Escherichia coli under the control of the lac promoter at 37 degrees C, NIR was produced as large inclusion bodies and little activity was detected. When cultivation was at 20 degrees C, most of the NIR was detected in the soluble fraction and a significant portion of the protein was translocated into the periplasmic space, accompanied by removal of its signal sequence.

Alcaligenes↗

PubMed1992

Significance of a new stratification of alkaline phosphatase and extent of disease in patients with prostate carcinoma with bone metastasis.

Bone is the most frequent site of metastatic prostate cancer and the prognosis of patients with bone metastasis is poor. The authors have investigated a semiquantitative system to evaluate bone metastatic lesions in terms of cancer-specific survival. Based on the extension of disease (EOD) grade proposed by Soloway and associates, a new EOD grading system obtained from bone scintigraphy alone and EOD score obtained from bone scintigraphy and alkaline phosphatase was studied in 164 patients with prostate cancer with metastatic bone involvement. In terms of a cancer-specific survival and prostate cancer death, both the new EOD grade and the EOD score were apparently superior to eight other items studied (age, medical score, gait disturbance, histologic grade, erythrocyte sedimentation rate, prostatic acid phosphatase, and alkaline phosphatase). Multivariate analysis revealed that the EOD score was better than the new EOD grade. This improvement was due to the elimination of false-positive or nonactive metastatic bone lesions on bone scintigraphy through the alkaline phosphatase evaluation.

Aged↗

PubMed1992

Age-related changes in transmitter glutamate and NMDA receptor/channels in the brain of senescence-accelerated mouse.

The senescence-accelerated mouse (SAM-P/8) is known as a murine model of aging and memory dysfunction. In the hippocampus and cerebral cortex of P/8, the contents of glutamic acid and glutamine were significantly higher than those of normal strain R/1 during 2 and 14 months. High K(+)-evoked endogenous glutamic acid release from the slices of P/8 was increased in comparison with R/1 at 9 and 11 months. In addition, the Bmax of [3H]dizocilpine (MK-801, channel blocker for N-methyl-D-aspartic acid receptor/channel) binding in the cerebral cortex was age-dependently decreased in P/8 but not in R/1. These results suggest that synaptic dysfunctions in the glutamatergic system occur in the CNS of SAM-P/8.

Aging↗

PubMed1992

Site-directed mutagenesis of pseudoazurin from Alcaligenes faecalis S-6; Pro80Ala mutant exhibits marked increase in reduction potential.

Pseudoazurin (a blue copper protein or cupredoxin) of a denitrifying bacterium Alcaligenes faecalis S-6 is a direct electron carrier for a Cu-containing nitrite reductase (NIR) of the same organism. Site-directed mutagenesis of the pseudoazurin was carried out using an Escherichia coli expression system. Replacement of Tyr74 by Phe to remove an internal hydrogen bond in the beta-barrel caused a slight decrease in heat stability as well as a requirement for a higher concentration of Cu2+ for production in the E. coli host. Exchange of Ala for Pro80 adjacent to His81, one of the four ligands binding a type I Cu atom, caused a marked increase in reduction potential by 139 mV without change in the optical absorption spectrum. The ability of the pseudoazurin to transfer electrons to NIR was markedly diminished but the apparent Km of NIR for pseudoazurin was not affected by the mutation. X-ray diffraction data collected on the oxidized and reduced forms of the Pro80Ala mutant show that a water molecule occupies the pocket created by the absent side chain. This observation suggests that the increase in reduction potential may be caused due to the increased solvent accessibility to the Cu atom. The electron density difference maps on these structures (at 2.0 A) show that this water moves during the change in oxidation state, and that there are small, but localized, conformational changes greater than 6.5 A from the copper site, as well as movement of both the Cu2+ and the cysteinate sulfur.

Alcaligenes↗

PubMed1992

Development of a chemical form discrimination system for 14C species in gaseous waste.

A new system was developed for discriminating the chemical form of 14C species in gaseous waste from nuclear facilities. The system consists of an air sample reservoir, a concentration apparatus, a radio-gas chromatograph, and microcomputers. An air sample, which is part of the gaseous effluent released from a stack of a facility, is automatically collected in the tank by trigger signals of stack monitors. After passing the air through a silica gel column, carbon species contained in it are recovered in an activated carbon-supported palladium trap held at -120 degrees C. The recovered species are swept with helium gas and analyzed by the radiogas chromatograph using an activated carbon column and gas-flow counters. Output signals of the gas-flow counters are continuously recorded by the microcomputer. By using this system, the chemical forms of 14C, such as CO, CO2, CH4, C2H4, C2H6, and C3H8 are identified and quantified. A detectable concentration of 0.3 mBq cm-3 for 14CO2 can be obtained. The system has been used to monitor the gaseous waste released from the radioisotope production laboratory and the Japan Research Reactor 2 at Japan Atomic Energy Research Institute.

Air Pollutants, Radioactive↗

PubMed1992

Degree of severity of pectus excavatum and pulmonary function in preoperative and postoperative periods.

Pulmonary function was evaluated in 138 patients with pectus excavatum, paying particular attention to the degree of severity of chest deformity. We defined the severity of deformity quantitatively based upon a computed tomographic index obtained from a computed tomogram. We recognized a positive relationship between computed tomographic index (x) and percent vital capacity (y), as follows: y = 137x + 58 (n = 138, r = 0.61, p < 0.05). Pulmonary function tests were performed from 2 to 42 months postoperatively. Vital capacity decreased about 10% from the baseline value during the initial 2 months after surgical treatment and recovered to the preoperative level by 1 year after surgery. At 42 months after surgical correction, the pulmonary function was maintained at the baseline level and the severity of deformity was significantly improved. Surgical procedures for the treatment of pectus excavatum--sternocostal elevation and sternal turnover--resulted in an excellent cosmetic result but did not importantly affect respiratory function.

Adolescent↗

PubMed1992

[A rare case of mediastinal neuroblastoma with pectus excavatum in a 4-month-old boy--a surgical report].

Screening of neuroblastoma is commonly performed on 6-month-old infants; therefore, its discovery in children younger than that age is extremely rare. However, a 4-month-old boy with pectus excavatum was found to also have mediastinal neuroblastoma after close examination. This 7 kg child had no apparent symptoms, yet revealed an egg-sized shadow along the right atrium in the chest X-ray film, and along the right side of the vertebrae on CT. Due to the increase in the size of the tumor after two months of observation, we suspected malignant neurogenic tumor and performed a thoracotomy. With a right posterolateral thoracotomy we removed the dark-brown, elastic tumor measuring 6 x 4 x 3 cm and located along the right side of the vertebrae from III through VIII ribs. The origin was the thoracic sympathicus and the pathological diagnosis of the tumor was neuroblastoma with rosset formation. After conducting a post-operative chemotherapy (Jame's protocol), no evidence of recurrence was observed at 33 months after surgical treatment. We summarized the previously reported seven surgically treated cases of Stage I mediastinal neuroblastoma at less than 12 months of age. Among the 2500 pectus excavatum surgeries that have been held at our department, non has been found to have mediastinal neuroblastoma.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1991

Effects of bifemelane hydrochloride, a brain function improver, on muscarinic receptors in the CNS of senescence-accelerated mouse.

Senescence-accelerated mouse (SAM-P/8) is known as a murine model of aging and memory dysfunction, compared with control mouse (SAM-R/1). In the hippocampus of 9-month-old SAM-P/8, the Bmax of [3H]QNB binding was decreased compared with that of SAM-R/1 at the same age. Single and repeated administrations of bifemelane to SAM-P/8 induced an increase in the Bmax of [3H]QNB binding in the hippocampus. From these results, bifemelane seems to exert pharmacological effects through possible activation of the cholinergic system in the hippocampus of SAM.

Aging↗

PubMed1991

M1 acetylcholine receptor-mediated phosphatidylinositol turnover in adult and senescent rat brain slices.

Phosphatidylinositol (PI) turnover via muscarinic acetylcholine (mACh) receptor was investigated using the cerebral cortex from adult rats. Activities in the cerebral cortex, hippocampus and striatum from senescent rats were compared with those from adult rat. Carbachol (1 mM)-stimulated [3H]IP accumulation in the presence of 10 mM LiCl was inhibited by pirenzepine more potently than by AF-DX 116. Although the displacing activity of carbachol for [3H]pirenzepine binding was decreased by 50 microM GTP gamma S, pretreatment of slices with pertussis toxin (PTX, 0.01-1.0 micrograms/ml) did not affect the carbachol-induced [3H]IP accumulation. In the slices from all 3 tissues, cerebral cortex, hippocampus and striatum, both incorporation of [3H]inositol and carbachol-stimulated [3H]IP accumulation were reduced at 28 months compared to those at 2 months. Furthermore, the Bmax values of [3H]pirenzepine binding in membranes from these three regions were diminished at the senescent stage. Taken together, the results suggest that an M1-subtype of muscarinic acetylcholine receptor could be involved in PI turnover via GTP-binding proteins insensitive to PTX. Age-related changes in M1-receptor mediated PI turnover seem to be in part due to the decreased number of M1-receptors with increasing age in the cerebral cortex, hippocampus and striatum; and some qualitative changes also seem to have occurred in the hippocampus of senescent rats in the mACh receptor-PI turnover system.

Aging↗

PubMed1990

Effects of repeated administrations of facteur thymique sérique (FTS) on biochemical changes related to aging in senescence-accelerated mouse (SAM).

Superoxide dismutase (SOD) activity,malondialdehyde (MDA) content and monoamine oxidase B (MAO-B) activity were measured in the brain, liver and kidney of a normal aging strain (R/1) and an accelerating aging strain (P/8) senescence-accelerated mice (SAM) at 9-10 months of age, and the effects of facteur thymique sérique (FTS) were examined. The activity of Cu,Zn-SOD in the kidney and MAO-B in the liver was significantly low and high in SAM-P/8 compared to SAM-R/1. FTS enhanced the activity of Mn-SOD and Cu,Zn-SOD in the kidney of SAM-P/8 and Cu,Zn-SOD activity in the brain of both SAM-P/8 and SAM-R/1. It decreased the activity of MAO-B in the liver and the contents of malondialdehyde (MDA) in the brain and kidney of SAM-P/8. Thus, FTS affects the biochemical factors related to senescence in SAM-P/8, a particular senescent animal model, and may thus possibly be effective as an anti-senescent medicine.

Aging↗

PubMed1989

Ligand-binding characteristics of [3H]QNB, [3H]prazosin, [3H]rauwolscine, [3H]TCP and [3H]nitrendipine to cerebral cortical and hippocampal membranes of senescence accelerated mouse.

The senescence accelerated mouse (SAM) is known as a murine model of aging and memory dysfunction. In the cerebral cortical membranes of male 9-month-old SAM mice, the Bmax values of [3H]rauwolscine and [3H]nitrendipine binding, and the values of both Kd and Bmax of [3H]TCP binding in the accelerated aging strain SAM-P/8, were significantly increased compared with the values in the control strain SAM-R/1. In hippocampal membranes, however, the Bmax values of [3H]quinuclidinyl benzilate and [3H]nitrendipine binding were significantly decreased in SAM-P/8 compared with those in SAM-R/1. These results suggest that muscarinic acetylcholine receptors, alpha 2-adrenoceptors, N-methyl-D-aspartate receptor channels and L-type Ca2+ channels are changed in cerebral cortex and hippocampus in SAM-P/8 at 9 months.

Aging↗

PubMed1989

Migration of radionuclides controlled by several different migration mechanisms through a sandy soil layer.

Column experiments have been carried out on the migration of 60Co and 137Cs through a sandy soil layer in order to examine the migration of radionuclides controlled by several different migration mechanisms. Radionuclide concentration distribution between the effluent and the sandy soil layer was measured after 10 L of the solution containing the radionuclides were introduced into the column from the top of the layer at a constant flow rate. Most of the 60Co and 137Cs remained attached to the layer, and a small amount of each radionuclide; at concentrations of 0.3 and 0.1%, respectively; flowed out from the soil layer. The migration of the mobile fraction of these radionuclides is different from that expected of an ideal cation. These results suggest that the mobile fraction of these radionuclides migrates as non-cationic forms which are not adsorbed into the soil matrix by equilibrium ion exchange.

Cesium Radioisotopes↗

PubMed1989

[Induction of pulmonary edema in rat with pulmonary artery air embolization and inhibitory effects of dilazep hydrochloride].

Inducing pulmonary edema in rat, air bubbles the diameter of which was about 0.3 mm were continuously infused into the right atrium through a catheter at the rate of 2.8 ml/kg/hr during 0.5, 1 and 2 hours, under controlled ventilation (tidal volume of 9 ml/kg and respiratory rate of 80/min) with 1% halothane in room air. Saline or Dilazep hydrochloride solution was simultaneously infused into the right atrium via another catheter. Pulmonary edema was evaluated by the measurement of the ratio of extravascular water weight of lung (g) to blood-free dry lung weight (g) (EVWW) using the gravimetric method and with histologic studies using the rapid freezing method. In control rats, which were sacrificed immediately after induction of anesthesia, the EVWW was 3.114 +/- 0.121 g/g blood-free dry lung (mean +/- 1 S.D. n = 8). In baseline experiments (2 hours ventilation and saline infusion without air embolization), the EVWW was 3.291 +/- 0.081 (n = 4). In air embolization groups with 2 hours saline infusion, EVWW were 3.756 +/- 0.170 (n = 4), 3.722 +/- 0.170 (n = 4) and 3.731 +/- 0.245 (n = 5) in 0.5, 1 and 2 hours infusion groups, respectively. Regardless of emboli infusion time perivascular cuffs and peribronchial cuffs were revealed in the 2 hour saline infusion groups. In the experiment in which the animals were sacrificed immediately after one hour infusion of air bubbles, there was no evidence of pulmonary edema and the EVWW of 3.060 +/- 0.092 (n = 4) in this group control and baseline were not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1988

Effect of vagus nerve cooling on hypercapnic and hypoxic ventilatory responses in anesthetized dogs.

We studied ventilatory responses under hypercapnic and hypoxic conditions in 18 lightly anesthetized dogs, using a vagus nerve cooling technique. One side of the cervical vagosympathetic trunks of dogs were previously severed, and a copper cooling probe was attached to the other side. When the cervical nerve was cooled below 7 degrees C, Hering-Breuer inflation reflex ceased. We found that when the vagus nerve was not cooled or cooled up to 7 degrees C, the respiratory frequency increased significantly in relation to hypercapnic gas inhalation. However, the increment of respiratory frequency was reduced by bilateral cervical vagotomy. On the other hand, the respiratory frequency in response to hypoxia increased significantly, even when bilateral vagotomy was done. The increment of the tidal volume in response to hypercapnic gas inhalation was reduced by the Hering-Breuer inflation reflex. We found that the effect of the vagus nerve on respiratory regulation was different between hypercapnic and hypoxic gas inhalation.

Animals↗