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Biomedical subjects

K Adachi

Publications and source records attributed to K Adachi.

At least 181 records · Page 10Linked to original sources
PubMed1998

Phosphorylation and activation of p70 S6 kinase by manganese in PC12 cells.

Previous study has shown that the treatment of PC12 cells with manganese, a MPTP-like neurotoxin, causes transcription-dependent apoptosis. This is a useful model system for the study of neuronal cell death. Manganese-induced apoptosis is accompanied by the induction of DNA fragmentation, expressions of c-Fos and c-Jun, and activation of the c-Jun N-terminal kinase U(JNK) pathway. Here, we report that manganese induces phosphorylation of p70 S6 kinase at Ser411 and Thr421/Ser424, and activates the enzyme. Thus, phosphorylation and activation of p70 S6 kinase are accompanied by transcription-dependent apoptosis, suggesting a role for p70 S6 kinase in this type of apoptosis.

Animals↗
PubMed1998

Role of beta112 Cys (G14) in homo- (beta4) and hetero- (alpha2 beta2) tetramer hemoglobin formation.

In order to assess the role of beta112 Cys in homo- and hetero-tetrameric hemoglobin formation, we expressed four beta112 variants (beta112Cys-->Asp, beta112Cys-->Ser, beta112Cys-->Thr, and beta112Cys-->Val) and studied assembly with alpha chains in vitro. beta112 Cys is normally present at beta1 beta2 and alpha1 beta1 interaction sites in homo- (beta4) and hetero-tetramers (alpha2 beta2). beta4 formation in vitro was influenced by the amino acid at beta112. beta112 Asp completely inhibited formation of homo-tetramers, whereas beta112 Ser showed only slight inhibition. In contrast, beta112 Thr or Val enhanced homo-tetramer formation compared with betaA chains. Association constants for homo-tetramer formation increased in the order of beta112Cys-->Ser, betaA, beta112Cys-->Thr, and beta112Cys-->Val, whereas the value for beta112Cys-->Asp was zero under the same conditions. These beta112 changes also affected in vitro alpha2 beta2 hetero-tetramer formation. Order of alpha2 beta2 formation under limiting alpha-globin chain conditions showed Hb betaC112S > Hb A > Hb S = Hb betaC112T = Hb betaC112V >>> Hb betaC112D. Hb beta112D can form tetrameric hemoglobin, but this beta112 change promotes dissociation into alpha and beta chains instead of alpha beta dimer formation upon dilution. These results indicate that amino acids at alpha1 beta1 interaction sites such as beta112 on the G helix play a key role in stable alpha beta dimer formation. Our findings suggest, in addition to electrostatic interaction between alpha and beta chains, that dissociation of beta4 homo-tetramers to monomers and hydrophobic interactions of the beta112 amino acid with alpha chains governs stable alpha1 beta1 interactions, which then results in formation of functional hemoglobin tetramers. Information gained from these studies should increase our understanding of the mechanism of assembly of multi-subunit proteins.

Chromatography, Gel↗
PubMed1998

Inhibition of NMDA receptors and nitric oxide synthase reduces ischemic injury of the retina.

This study was performed to examine the roles of body temperature, NMDA receptors and nitric oxide (NO) synthase in post-ischemic retinal injury in rats. Cell loss in the ganglion cell layer and thinning of the inner plexiform layer were observed 7 days after ischemia. Cell loss in the ganglion cell layer but not thinning of the inner plexiform layer was reduced by hypothermia during ischemia. Intravenous injection of dizocilpine (MK-801) or Nomega-nitro-L-arginine methyl ester (L-NAME) prior to ischemia ameliorated retinal injury. These results suggest that activation of NO synthase following NMDA receptor stimulation is involved in ischemia-induced retinal injury.

Animals↗
PubMed1998

Molecular cloning and characterization of the murine staf cDNA encoding a transcription activating factor for the selenocysteine tRNA gene in mouse mammary gland.

We have isolated and characterized a cDNA encoding a transcription activating factor for the mouse selenocysteine tRNA (tRNAsec) gene from mouse mammary gland. The full-length cDNA, designated m-Staf, has a 1878-base pair open reading frame encoding 626 amino acids. The predicted amino acid sequence of m-Staf is highly homologous to that of Staf, another selenocysteine tRNA gene transcription activating factor of Xenopus laevis. Like Staf, m-Staf contains seven tandemly repeated zinc fingers and four repeated motifs. Gel shift assays indicated that the recombinant m-Staf specifically bound to the activator element region in the mouse tRNAsec gene. Transient co-transfection experiments in Drosophila Schneider cells, which lack endogenous Staf-like binding activity, showed that m-Staf increased the mouse tRNAsec gene transcription about 15-fold, whereas it stimulated Pol II-dependent thymidine kinase promoter only 2-fold. Northern blot analysis detected the presence of a 3.4-kilobase pair m-Staf transcript, which was widely but differentially expressed in various murine tissues. The binding activity of m-Staf in mouse mammary gland was undetectable during virgin and postlactating periods but increased markedly in parallel with the increase of tRNAsec transcript during the periods of pregnancy and lactation, when the gland undergoes growth and development. These results indicate that m-Staf is a transcriptional activator of the mouse tRNAsec gene and that its binding activity in the mammary gland undergoes developmental alterations.

Amino Acid Sequence↗
PubMed1998

Rapid determination of vitamins A and E in serum with surfactant as a diluent by column-switching high-performance liquid chromatography.

The rapid and simple determination of fatty vitamins (vitamins A and E) in serum by high-performance liquid chromatography with a column-switching technique was investigated. The dilution of serum with an aqueous solution containing surfactant and organic solvent and the use of an aqueous solution with organic solvent as a sample pretreatment were an effective means of improving the sample recovery. To prevent sample decomposition during storage, the addition of an antioxidant reagent into the diluent was required. Under the optimal conditions, the relative standard deviation (R.S.D.) values against the standard samples were 1.12% (16.7 I.U./dl), 0.25% (333 I.U./dl) for vitamin A, and 1.02% (0.43 microgram/ml), 0.45% (8.5 micrograms/ml) for vitamin E, respectively. The relative coefficients (r2) between the sample amounts in serum and the peak areas were 1.0000 in the range from 16.7 to 667 I.U./dl (for vitamin A) and 0.9998 from 0.434 to 17.46 micrograms/ml (for vitamin E). The recoveries of vitamins from spiked serums were ca. 100% (vitamin A) and ca. 86% (vitamin E), respectively. By the combination of an on-line deproteination column and diluting solution, the simple and rapid determination of fatty vitamins could be routinely achieved in 18-min intervals.

Chromatography, High Pressure Liquid↗
PubMed1998

Effects of increased anionic charge in the beta-globin chain on assembly of hemoglobin in vitro.

Studies on assembly in vitro of alpha-globin chains with recombinant beta16 Gly-->Asp, beta95 Lys-->Glu, beta120 Lys-->Glu and beta16 Gly-->Asp, 120 Lys-->Glu human beta-globin chain variants in addition to human betaA- and betaS-globin chains were performed to evaluate effects of increased anionic charge in the beta chain on hemoglobin assembly using soluble recombinant beta-globin chains expressed in bacteria. A beta112 Cys-->Asp change was also engineered to monitor effects on assembly of increased negative charge at alpha1beta1 interaction sites. Order of tetramer formation in vitro under limiting alpha-globin chain conditions showed Hb betaG16D, K120E = Hb betaK120E = Hb betaK95E > Hb betaG16D > Hb A > Hb S >>> Hb betaC112D. In addition, beta112 Cys-->Asp chains exist as monomers rather than beta4 tetramers in the absence of alpha chains, and the beta chain in Hb betaC112D tetramers was readily exchanged by addition of betas. These results suggest that affinity between alpha and beta chains is promoted by negatively-charged beta chains up to a maximum of two additional net negative charges and is independent of location on the surface except at the alpha1beta1 interaction site. In addition, our findings show that beta112 Cys on the G helix is critical for facilitating formation of stable alphabeta dimers, which then form functional hemoglobin tetramers, and that beta112 Cys-->Asp inhibits formation of stable alpha1beta1 and beta1beta2 interactions in alpha2beta2 and beta4 tetramers, respectively.

Anions↗
PubMed1998

Clinical, pathological, and genetic features of limb-girdle muscular dystrophy type 2A with new calpain 3 gene mutations in seven patients from three Japanese families.

We report on the clinical, pathological, and genetic features of 7 patients with limb-girdle muscular dystrophy type 2A (LGMD2A) from three Japanese families. The mean age of onset was 9.7+/-3.1 years (mean+/-SD), and loss of ambulance occurred at 38.5+/-2.1 years. Muscle atrophy was predominant in the pelvic and shoulder girdles, and proximal limb muscles. Muscle pathology revealed dystrophic changes. In two families, an identical G to C mutation at position 1080 the in calpain 3 gene was identified, and a frameshift mutation (1796insA) was found in the third family. The former mutation results in a W360R substitution in the proteolytic site of calpain 3, and the latter in a deletion of the Ca2+-binding domain.

Age of Onset↗
PubMed1998

Myocardial DNA strand breaks are detected in biopsy tissues from patients with dilated cardiomyopathy.

BACKGROUND: Progressive damage of cardiomyocytes with interstitial and replacement fibrosis accompanied by less inflammatory cell infiltration is observed in patients with dilated cardiomyopathy (DCM), suggesting some other mechanisms rather than necrotic cell death. HYPOTHESIS: The aim of this study was to assess the possible involvement of apoptotic process in the pathogenesis of DCM and myocarditis. METHODS: Endomyocardial biopsy was performed in patients with DCM (n = 9), myocarditis (n = 4), or atypical chest pain syndrome (as controls; n = 5). The TUNEL method was used for in situ detection of oligonucleosomal DNA strand breaks. RESULTS: The TUNEL-positive cells were observed in three of nine patients with DCM and in all four with myocarditis, but in none of the controls. The TUNEL-positive nuclei were observed exclusively in cardiomyocytes in DCM, whereas in myocarditis they were detected mainly in interstitial cells and in a few myocytes. In DCM, interstitial fibrosis was greater in the TUNEL-positive than in TUNEL-negative patients (p < 0.05). In either DCM or myocarditis, electron microscopic examination could not reveal morphologic features of apoptosis of cardiomyocytes. CONCLUSION: The DNA strand breaks were detected in cardiomyocytes in patients with DCM and mainly in interstitial cells in myocarditis. It is possible that the DNA strand breaks can be involved in mechanisms of progressive loss of functional cardiac units in these myocardial diseases.

Adult↗
PubMed1998

Primary sclerosing pancreatitis and cholangitis.

CONCLUSION: The clinical course of our patient suggests the association between chronic pancreatitis and primary sclerosing cholangitis (PSC), as well as the usefulness of prednisolone for the treatment of this condition. BACKGROUND: Although alterations in the pancreatic duct have been reported, the association between chronic pancreatitis and PSC remains uncertain. METHODS AND RESULTS: A long-term follow-up case of chronic pancreatitis accompanied by PSC is presented. A 58-yr-old man complaining of epigastric distress was admitted to our hospital in July 1990. Endoscopic retrograde cholangio-pancreatography (ERCP) showed a stricture of the distal common bile duct and a narrowing of the main pancreatic duct (MPD) with mild ectasia of its branches in the head of the pancreas. ERCP taken in June 1992 revealed localized narrowings in both the right and the left main hepatic ducts, and irregularity of the MPD through the entire pancreas. An ERCP taken in June 1996 showed a progression of the narrowings of the bile ducts. The patient was diagnosed as having chronic pancreatitis accompanied by PSC. ERCP revealed a remarkable improvement of the bile ducts after 4 wk of treatment with prednisolone.

Anti-Inflammatory Agents↗
PubMed1998

Hypertrophic cranial pachymeningitis in a patient with aplastic anemia.

We report on a 13-year old girl with severe aplastic anemia and hypertrophic cranial pachymeningitis. She was admitted to our hospital with severe headache and vomiting. A computerized tomographic (CT) scan of the brain on the third day of symptoms showed a hyperdense area in the tentorial region. Magnetic resonance imaging (MRI) showed iso-intensity in the same tentorial region in T1- and T2-weighted images, and gadolinium enhancement of this region suggested a thickened dura mater. Initially, a diagnosis of subdural or subarachnoid hemorrhage was made. Since her platelet count was low (3000/microl) making the patient a poor-risk candidate for surgery, and the area was limited to the dura mater, conservative therapy, including glycerol administration and platelet transfusion, was carried out. Despite clinical improvement 10 days after admission without specific therapy, the iso-intense region on the left side of the tentorial region remained unchanged on MRI. On the other hand, the iso-intense area on the right side of the tentorial region became hyperdense on T1-weighted MRI images and was also enhanced by gadolinium. Cerebrospinal fluid findings were normal except for slightly elevated protein at 62 mg/dl. A diagnosis of hypertrophic cranial pachymeningitis of the tentorial dura mater with hemorrhage on the right side was made. Although hypertrophic cranial pachymeningitis is a rare disease, it must be considered in the differential diagnosis of severe headache in a case of aplastic anemia.

Anemia, Aplastic↗
PubMed1998

Different manners of sarcoglycan expression in genetically proven alpha-sarcoglycan deficiency and gamma-sarcoglycan deficiency.

We investigated the expression of alpha-sarcoglycan, beta-sarcoglycan, gamma-sarcoglycan, and delta-sarcoglycan immunohistochemically in three patients with mutations of the alpha-sarcoglycan gene and a patient with a mutation of the gamma-sarcoglycan gene. Although each of the four sarcoglycans were decreased on the muscle membranes of all the patients, different expression patterns for each were seen among the patients. In patients with mutations of the alpha-sarcoglycan gene, beta-, gamma- and delta-sarcoglycans were relatively preserved as compared to greatly reduced alpha-sarcoglycan. However, the patient with a mutation of the gamma-sarcoglycan gene showed marked reduction of gamma-sarcoglycan as compared to partially preserved alpha- and beta-sarcoglycans, and well-preserved delta-sarcoglycan. These results suggest that each sarcoglycan component in sarcoglycanopathy does not decrease in the same manner, and that mutations of the sarcoglycan gene can be predicted, at least in part, by means of sensitive immunohistochemistry for each sarcoglycan.

Child↗
PubMed1998

Mechanism of the pathogenesis of glutamate neurotoxicity in retinal ischemia.

PURPOSE: This study was carried out to examine the involvement of glutamate and nitric oxide neurotoxicity in ischemia/reperfusion-induced retinal injury in vivo. METHODS: We monitored glutamate release from in vivo cat retina during and after pressure-induced ischemia using a microdialysis technique. Morphometric studies were performed to study the effects of MK-801 (dizocilpine), L-NAME (N omega-nitro-L-arginine methyl ester), and D-NAME (N omega-nitro-D-arginine methyl ester) on the histological changes in the rat retina induced by ischemia or intravitreal injection of NMDA (N-methyl-D-aspartate; 200 nmol). RESULTS: A large release of glutamate occurred during ischemia, followed by a marked release after reperfusion. Histological changes occurred selectively in the inner part of the retina after ischemia as well as intravitreal injection of NMDA. Pretreatment with intravenous injection of MK-801 or L-NAME significantly inhibited the ischemic injury of the inner retina. Intravitreal injection of L-NAME inhibited NMDA-induced neurotoxicity in the retina. CONCLUSION: These findings indicate that nitric oxide mediates neurotoxic actions of glutamate which are responsible for ischemic injury in the retina.

Animals↗
PubMed1998

A combination of preductal aortic coarctation and type B dissection: report of a case.

We present herein the case of a 39-year-old man found to have significant coarctation of the preductal aorta combined with a type B dissection, associated with Marfan's syndrome. This extremely rare pathological combination could be defined preoperatively only by a three-dimensional computed tomography scan. By means of selective cerebral perfusion, the coarctation was resected, and the total aortic arch was replaced with a Dacron graft.

Adult↗
PubMed1998

Mitochondrial function in Babesia microti and Babesia rodhaini.

The role of mitochondria in the energy metabolism of Babesia microti and Babesia rodhaini was investigated. A variety of mitochondrial inhibitors showed greater sensitivity to B. microti than to B. rodhaini. Additionally, alpha-glycerophosphate- and succinate-cytochrome c reductase activities in the crude mitochondrial fraction from B. microti were substantially higher than those from B. rodhaini. Our results suggest that the mitochondria of these parasites possess a series of "classical" apparati for energy production and their relative functional role may be quantitatively greater in B. microti when compared with B. rodhaini.

ATP Synthetase Complexes↗