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Biomedical subjects

T Adachi

Publications and source records attributed to T Adachi.

At least 217 records · Page 12Linked to original sources
PubMed1997

Ion-exchange high-performance liquid chromatographic separation of protein variants and isoforms on MCI GEL ProtEx stationary phases.

Protein variants and isoforms were successfully separated on MCI GEL ProtEx ion-exchange HPLC columns. There was no irreversible adsorption of proteins, and sample proteins were quantitatively recovered. Species variants of cytochrome c (bovine, horse and rabbit) were completely separated on a sulfopropyl (ProtEx-SP) stationary phase in a gradient system. Diethylaminoethyl (ProtEx-DEAE) phase was determined to be effective for the separation of human growth hormone and its deamidated isoforms. These characteristics of ProtEx stationary phases may be attributed both to particle uniformity and to hydrophillic surface coverage of the base polymeric material.

Animals↗
PubMed1997

Brain acetylhydrolase that inactivates platelet-activating factor is a G-protein-like trimer.

The platelet-activating factor PAF (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) is a potent lipid first messenger active in general cell activation, fertilization, inflammatory and allergic reactions, asthma, HIV pathogenesis, carcinogenesis, and apoptosis. There is substantial evidence that PAF is involved in intracellular signalling, but the pathways are poorly understood. Inactivation of PAF is carried out by specific intra- and extracellular acetylhydrolases (PAF-AHs), a subfamily of phospholipases A2 that remove the sn-2 acetyl group. Mammalian brain contains at least three intracellular isoforms, of which PAF-AH(Ib) is the best characterized. This isoform contains a heterodimer of two homologous catalytic subunits alpha1 and alpha2, each of relative molecular mass 26K, and a non-catalytic 45K beta-subunit, a homologue of the beta-subunit of trimeric G proteins. We now report the crystal structure of the bovine alpha1 subunit of PAF-AH(Ib) at 1.7 A resolution in complex with a reaction product, acetate. The tertiary fold of this protein is closely reminiscent of that found in p21(ras) and other GTPases. The active site is made up of a trypsin-like triad of Ser 47, His 195 and Asp 192. Thus, the intact PAF-AH(Ib) molecule is an unusual G-protein-like (alpha1/alpha2)beta trimer.

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1997

Possible involvement of pertussis toxin-sensitive G protein in hepatocyte growth factor-induced signal transduction in cultured rat hepatocytes: pertussis toxin treatment inhibits activation of phospholipid signaling, calcium oscillation, and mitogen-activated protein kinase.

Treatment of primary cultured rat hepatocytes with hepatocyte growth factor (HGF) gives rise to inositol phosphate formation, cytosolic calcium oscillation, activation of mitogen-activated protein (MAP) kinase and phospholipase D (PLD), and arachidonic acid release, leading to DNA synthesis. Pretreatment of cultured hepatocytes with pertussis toxin (PT), which is known to adenosine diphosphate-ribosylate Gi and Go guanine nucleotide -binding proteins and to inhibit their functions, partially inhibited HGF-induced [3H]thymidine incorporation in a concentration-dependent manner. These results suggest that HGF-mediated DNA synthesis of hepatocytes is partly regulated via PT-sensitive guanine nucleotide-binding protein. Therefore, the effects of PT treatment on HGF-induced signal-transduction pathways were investigated. HGF-induced MAP kinase activation and arachidonic acid release were decreased by PT treatment, whereas PLD activation was diminished by PT to the level of unstimulated control. PT also interfered with HGF-induced inositol phosphate formation and cytosolic calcium oscillation. These results suggest that both PT-sensitive and PT-insensitive pathways are involved in HGF-induced signaling.

Animals↗
PubMed1997

Dumbbell-shaped jugular foramen schwannoma.

The authors present a case of dumbbell-shaped schwannoma arising from the vagus nerve. A 40-year-old woman was admitted with a 3-month history of hearing loss on the left ear without vertigo. Neuro-otological examinations revealed retrocochlear deafness with abnormal left vestibular function. Magnetic resonance imaging revealed a dumbbell-shaped tumor of the jugular foramen. The tumor was removed through a cervical-transmastoid approach using Cavitoron ultrasonic surgical aspiration. Two months after the operation, the patient's hearing loss had improved, although she still had some aspiration of saliva and hoarseness.

Adult↗
PubMed1997

Polymorphism of extracellular superoxide dismutase (EC-SOD) gene: relation to the mutation responsible for high EC-SOD level in serum.

Extracellular superoxide dismutase (EC-SOD) with amino acid substitution R213G generated by the nucleotide substitution 760C-->G in the heparin binding domain is responsible for the high EC-SOD level in serum. We identified the two DNA polymorphic sites in the coding region of EC-SOD gene related to the 760C-->G and determined the allele frequencies. The polymorphism were A and G at nucleotide position (nt.) 241 and C and T at nt. 280 near the N-terminal. The haplotype frequencies in Japanese were 241A280C: 0.45, 241G280T: 0.37, and 241G280C: 0.18. The haplotype of 241A280T did not exist. The mutation 760C-->G must occur on the allele having the haplotype of 241G280T.

Extracellular Space↗
PubMed1997

Expansion of the IR in the chloroplast genomes of buckwheat species is due to incorporation of an SSC sequence that could be mediated by an inversion.

The chloroplast genomes in buckwheat species contain large inverted repeats which are at least 4 kbp longer than the majority of those in land plants. The length of the buckwheat inverted repeats was attributable to an additional region located adjacent to the borders of the small single-copy region. We have cloned and sequenced a 5. 2-kbp SmaI fragment corresponding to this extra region in the inverted repeats. A homology search revealed that the sequence of the SmaI fragment is highly homologous to one side of the small single-copy region of the inverted repeats in dicot chloroplast DNAs such as tobacco and beechdrops. Interestingly, a 3.7-kbp segment in the middle of the SmaI fragment is inserted in the opposite orientation relative to those of the other dicot species, and 17-bp direct repeats are found located at both the ends of the additional region. These results suggest that expansion of the inverted repeats in buckwheat chloroplast DNA might have been associated with an inversion.

Chloroplasts↗
PubMed1997

A human UDP-GalNAc: polypeptide, N-acetylgalactosaminyltransferase type 1 gene is located at the chromosomal region 18q12.1.

The cDNA clone encoding human UDP-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase-1 (GalNAc-T1) was isolated from colon tissue by a reverse transcriptase-polymerase chain reaction (RT-PCR). Using fluorescence in situ hybridization, the position of the GalNAc-T1 gene was shown to be localized at the human chromosomal region, 18q12.1.

Chromosome Banding↗
PubMed1997

Interleukin-2-dependent augmentation of the anti-TNP antibody production by sodium butyrate in cultured murine splenic B cells.

Previously we found that sodium butyrate (NaBu) markedly enhanced production of the antibody specific for a T-cell-dependent antigen, sheep red blood cells (SRBC) in murine splenocytes (Kishiro, Y., Ueda, K., Fujiwara, M. and Yamamoto, I., Jpn J. Phamacol., 1994 66, 369-376. To gain a better understanding of the target cells for NaBu's action on antibody responses, we have utilized the T-cell-independent antigen, trinitrophenyl-lypopolysaccharide (TNP-LPS) as a stimulant and have examined an effect of NaBu on the anti-TNP antibody production in vitro. NaBu markedly increased the anti-TNP plaque-forming cell (PFC) responses in murine whole splenocytes, but not in murine splenic B cells. Addition of T-cells or the concanavalin A supernatant (CAS) from murine splenocytes to the B cell cultures completely restored the enhancing effect of NaBu. This effect of CAS was totally blocked by an anti-interleukin (IL)-2 antibody and partially by an anti-IL-1 beta or anti-IL-4 antibody. The full enhancing effect of NaBu was also detected when IL-2 was added to the B cell cultures, while IL-2 alone had no stimulatory effect on the control PFC response. IL-1 beta alone significantly stimulated the antibody production and adding NaBu to this IL-1 beta-supplemented culture caused a further increase. Neither IL-4 alone nor NaBu plus IL-4 had any effect on the PFC response. NaBu did not affect the expression of the IL-2 receptor alpha- and beta-chains in B cells stimulated with TNP-LPS. These results suggest that NaBu is an agent that promotes B cell differentiation in vitro in an IL-2-dependent manner.

Animals↗
PubMed1997

Different mechanisms of ischemic adaptation to repeated coronary occlusion in patients with and without recruitable collateral circulation.

OBJECTIVES: The aim of this study was to investigate the interaction between ischemic preconditioning (IP) and collateral recruitment (CR) during ischemic adaptation in patients. BACKGROUND: The mechanism of ischemic adaptation still remains controversial in humans. METHODS: The clinical, electrocardiographic, hemodynamic and echocardiographic responses to three 150-s occlusions of the left anterior descending coronary artery were assessed in relation to CR in 18 patients with effort angina undergoing elective percutaneous transluminal coronary angioplasty. RESULTS: During the first occlusion, recruitable collateral circulation (RCC) to the occluded myocardium was detected by myocardial contrast echocardiography in 6 patients (Group C) and was not seen in 12 (Group N). In Group N, all patients manifested signs of severe ischemia during each inflation. However, their symptoms and ST segment shift significantly decreased from the first to the third occlusions, suggesting the occurrence of IP. The elevation of mean pulmonary artery pressure and deterioration of anterior wall motion were comparable between the first and the third occlusions in Group N. In contrast, myocardial ischemia was significantly less marked during occlusion in Group C than in Group N, and no preconditioning effect was observed. The extent of RCC did not differ between the first and the third occlusions in each group. CONCLUSIONS: Both IP and CR may play independent roles in ischemic adaptation in humans. With RCC, myocardial ischemia was greatly reduced. Without RCC, preconditioning clinically and electrocardiographically lessened myocardial ischemia but failed to preserve left ventricular function.

Angina Pectoris↗
PubMed1997

Characterization of a novel rice bZIP protein which binds to the alpha-globulin promoter.

Many plant basic leucine-zipper (bZIP) proteins have been isolated several of which have been shown to play a role in seed-specific gene expression. We isolated a novel bZIP protein (REB) gene encoding 425 amino acid residues from rice endosperm, which is similar to Opaque-2 heterodimerizing protein (OHP) of maize. The gene product, termed REB, contains Pro- and Gly-rich regions at its N terminus, followed by the typical basic and leucine-repeat regions. Recombinant REB binds to the region from -754 to -562 in the alpha-globulin gene promoter, but not to promoters of other major storage genes such as glutelin, prolamin and albumin. The 5' region of the alpha-globulin gene possesses three binding sites for REB, which were determined as GCCACGT(A/C)AG, by using synthetic oligonucleotides. A Super-shift assay using anti-REB antibody suggested that REB is a major DNA-binding protein for the alpha-globulin gene promoter in rice endosperm.

Alpha-Globulins↗
PubMed1997

The effect of xenon on spinal dorsal horn neurons: a comparison with nitrous oxide.

We compared the effects of xenon (Xe) on the spinal cord dorsal horn neurons with those of nitrous oxide (N2O) in cats anesthetized with chrolarose and urethane. We assessed the potency of both anesthetics by the inhibition of wide dynamic range neuron responses evoked by cutaneous noxious (pinch) stimulation to a hindpaw. During 70% Xe inhalation, the responses of 7 of 11 neurons to pinch stimulation were suppressed. N2O, 70%, suppressed it in 8 of 11 neurons. The potency of Xe and N2O was compared in six neurons that were suppressed by both anesthetics. After 20 min of Xe inhalation, the response to pinch was suppressed to 49.5% +/- 8.2% (mean +/- SE), while N2O, 70% in oxygen, suppressed it to 45.9% +/- 7.9%. The difference between N2O and Xe was not significant. We conclude that Xe and N2O suppress the spinal cord dorsal horn neurons to a similar degree.

Anesthetics, Inhalation↗
PubMed1997

Effects of isoflurane on in vivo release of acetylcholine in the rat cerebral cortex and striatum.

BACKGROUND: Acetylcholine (ACh) is one of the major excitatory neurotransmitters in the central nervous system, and changes in neural activity induced by anesthesia alter the release of ACh. However, the effects of isoflurane, one of the most widely used volatile anesthetics, on ACh release are not known. The present study attempts to clarify the dose-effect relationship of isoflurane on the in vivo release of ACh in rat brains. METHODS: Changes in the extracellular concentration of ACh and choline in the cerebral cortex and striatum induced by 0.5, 1.0, and 1.5 minimum alveolar concentration (MAC) of isoflurane were determined using a brain microdialysis technique. RESULTS: In the cortex, the ACh release decreased to 30.8+/-10.1 (mean+/-SEM), 10.2+/-4.1, and 8.1+/-2.9% of basal value by increasing doses of isoflurane, and in the striatum, to 73.3+/-4.4, 49.2+/-4.2, and 40.7+/-4.5%. The ACh release rapidly recovered control levels with the discontinuance of isoflurane. Choline concentration was not changed significantly by isoflurane except for a decrease to 74.8+/-4.6% in the striatum by 0.5 MAC. In both the cortex and striatum, the choline concentration decreased with the discontinuance of isoflurane to 70.3+/-13.3, and 68.2+/-5.4%, respectively. CONCLUSION: The fact that all classic anesthetics reported previously, as well as isoflurane, reduce ACh release supports the hypothesis that the suppression of cholinergic cells is, at least in part one of the mechanisms of anesthesia.

Acetylcholine↗
PubMed1997

Characterization of energy metabolism and blood flow distribution in myocardial ischemia in hemorrhagic shock.

To characterize the mechanisms for myocardial ischemia induced by hemorrhagic shock, 29 dogs were subjected to hemorrhage at a mean aortic pressure (MAoP) of 30-60 mmHg. After 10 min of hemorrhage, the beating hearts were rapidly cross sectioned and freeze clamped to visualize the two-dimensional distribution of myocardial ischemia with NADH fluorescence (NADH-F) in 22 dogs. NADH-F was developed at an MAoP of 40 mmHg or less and involved both the subendocardial half and the subepicardial half of the left ventricle [34 +/- 14 vs. 20 +/- 14% (P < 0.05) and 65 +/- 16 vs. 52 +/- 15% (not significant) of the cross-sectional area of the left ventricular slice at MAoP levels of 40 and 30 mmHg, respectively]. Magnified NADH-F photography demonstrated heterogeneously distributed microischemic lesions with a columnar shape (mode of short-axis length, 60-80 microns). NADH-F-guided microsamplings revealed higher NADH and lactate concentrations in a positive NADH-F area than those in a negative NADH-F area. The ratio of endocardial to epicardial blood flow was maintained at a relatively high level (1.07 +/- 0.07 and 0.88 +/- 0.07 at MAoP levels of 40 and 30 mmHg, respectively; n = 7 dogs), and the reactive hyperemia was preserved as well. In conclusion, myocardial ischemia in early hemorrhagic shock was characterized by minimal transmural heterogeneity and marked heterogeneity between contiguous small regions.

Animals↗
PubMed1997

Existence of c-kit receptor-positive, tryptase-negative, IgE-negative cells in human allergic nasal mucosa: a candidate for mast cell progenitor.

The accumulation of mast cells in the allergic nasal epithelium is well known, yet the mechanism remains unclear. We studied whether there is a candidate for mast cell progenitors in the allergic nasal mucosa tissue removed at the time of surgery. We first confirmed that most mast cells in nasal mucosae of 10 nasal allergic patients had c-kit receptor by immunohistochemistry using the mirror sectioning technique. We then investigated whether c-kit receptor+, tryptase-, IgE- cells existed in nasal mucosae of 15 nasal allergic patients and 15 nonallergic ones using sequential triple immunohistochemistry. We observed the area in which 1,000 to 1,100 tryptase-positive cells (mast cells) existed in both the subepithelial layer and the deep layer of each nasal lamina propria. The epithelial layer above this area was also examined. Some c-kit receptor+, tryptase- cells existed in the nasal mucosae of 11 patients with nasal allergy and of 5 patients with nonallergic rhinitis. From one to four of these cells in the nasal epithelium and subepithelial layer of the 4 allergic patients were IgE-negative. In contrast, no IgE-negative cells existed in the deep layer of allergic nasal mucosae or in any nonallergic nasal mucosae. Our results suggest that mast cell progenitors, hematopoietic progenitor cells or multipotential blood cells exist in the allergic nasal mucosa, and may contribute to the increase of mast cells in the epithelium and subepithelial layer of allergic nasal mucosa.

Adolescent↗
PubMed1997

Effect of extracranial carotid artery stenosis and other risk factors for stroke on periventricular hyperintensity.

BACKGROUND AND PURPOSE: The pathogenesis of periventricular hyperintensity (PVH) is still uncertain. We investigated the relationship between PVH and risk factors for cerebrovascular diseases, especially extracranial carotid artery stenosis (ECAS). METHODS: We studied PVH and ECAS in 323 subjects between 1991 and 1994. Using 1.5-T MRI scan images, we measured PVH quantitatively at eight points and evaluated cerebral infarction. Duplex carotid sonography was performed on the carotid arteries bilaterally and used to divide the severity of ECAS into five grades. Risk factors for cerebrovascular diseases and atherosclerotic complications were assessed from the clinical history. RESULTS: Age was significantly correlated with the size of frontal and whole PVH (P < .01). Frontal PVH was significantly more severe in subjects with hypertension (P < .05). Frontal, occipital, and whole PVH were significantly more severe in subjects with a history of cerebrovascular accident (P < .01). Other risk factors and atherosclerotic complications were not correlated with PVH. There were no significant differences in the severity of PVH among the five groups of ECAS. The severity of PVH in each region was not related to ECAS. There was no significant difference in the age of patients in relation to the five grades of ECAS. However, PVH was significantly more severe in subjects with lacunar infarction or infarction of the deep border zone (P < .05). There was no relationship between PVH and cortical infarction or infarction of the cortical border zone. CONCLUSIONS: PVH correlated with age, hypertension, and past history of cerebrovascular disease but not with ECAS. PVH was significantly more severe in lacunar infarction and infarction of the deep border zone. These results suggest that small-vessel disease may underlie the pathogenesis and development of PVH.

Adult↗
PubMed1997

Measurement of velopharyngeal movements induced by isolated stimulation of levator veli palatini and pharyngeal constrictor muscles.

The levator veli palatini (LVP) and superior pharyngeal constrictor muscles (PC) close the velopharynx. However, for the velopharyngeal movements to be understood in detail, each muscle contraction must be analyzed precisely. This study was performed to clarify the velopharyngeal movement which was induced by a single muscle contraction, LVP or PC. Using a nasopharyngeal fiberscope, we analyzed the velopharyngeal movement associated with the contraction of the LVP and PC muscles in mongrel dogs. To elicit the maximal contraction of each muscle, we applied repetitive electrical stimulation to each peripheral nerve efferent to the LVP or PC muscle. Stimulation with a frequency of 77 Hz and 83 Hz induced maximal tension in the LVP and PC muscles, respectively, in isometric contraction. In a second series of experiments, fiberscopic views of the velopharyngeal movements associated with each muscle's maximal contraction were recorded. The degree of closure was calculated at several sections. The LVP muscle pulled the caudal fourth of the soft palate, while the PC projected the posterior wall at the level of the caudal end of the soft palate. The PC muscle also projected the lateral wall of the velopharynx. The effect of LVP contraction on the lateral wall was very small. These results show that the velopharyngeal movement associated with LVP contraction is very different from that with PC contraction.

Animals↗
PubMed1997

Purification and characterization of pranlukast hydrolase from rat liver microsomes: the hydrolase is identical to carboxylesterase pI 6.2.

Two carboxylesterases with pI 6.0 and 6.2 derived from rat liver microsomes were purified. The two isozymes were remarkably different in substrate specificity, but they had equal enzymatic activity for alpha-naphthyl acetate and were inhibited equally by phenylmethylsulfonyl fluoride (PMSF) and bis-(4-nitrophenyl) phosphate (BNPP). Carboxylesterases pI 6.0 and 6.2 are identical to the enzymes referred to as hydrolase A and B, respectively, from the results of amino acid sequence analyses. Pranlukast was effectively hydrolyzed by carboxylesterase pI 6.2 but not by the pI 6.0 enzyme, and the difference in the pranlukast metabolism between the human and the rat could be explained by the substrate specificity of carboxylesterase. Furthermore, prodrugs of angiotensin converting enzyme inhibitors were found to be converted to the active drugs after hydrolysis by the carboxylesterases pI 6.0 and 6.2. Carboxylesterases generally catalyze the hydrolysis of ester-type drugs preferentially rather than amide-type drugs.

Amino Acid Sequence↗