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Biomedical subjects

Y Katayama

Publications and source records attributed to Y Katayama.

At least 199 records · Page 11Linked to original sources
PubMed1999

Intraluminal increase of superoxide anion following transient focal cerebral ischemia in rats.

Using a modification of Karnovsky's Mn2+/diaminobenzizine (DAB) technique, we examined the production of superoxide anion (.O-2) in the vascular lumen following transient occlusion and reperfusion of the left middle cerebral artery (MCA) in Sprague-Dawley rats. The MCA was occluded for 2 h using an intraluminal suture method. Zero, 15, 30, and 60 min after reperfusion, animals were perfused transcardially with buffer containing Mn2+ and DAB, and brain samples were prepared for light and electron microscopic examination. The amber reaction deposits of.O-2 were observable to the naked eye along the major cerebral vessels of the ischemic hemisphere after each reperfusion period. Upon microscopic examination the deposits were revealed to be within arterial, capillary, and venular lumen. The amount of reaction deposits in the ischemic hemisphere corresponded to the duration of reperfusion. The formation of.O-2 was suppressed when the perfusate contained superoxide dismutase and when either Mn2+ or DAB was omitted, confirming that the reaction products produced are due to the enhanced production of.O-2. These results show that there is a progressive increase in intraluminal. O-2 during reperfusion following an ischemic insult which may participate in the aggravation of cerebral damage.

Animals↗
PubMed1999

Intraoperative enzyme-amperometric monitoring of extracellular glutamate concentration with a dialysis electrode in ischemic human brain.

Changes in the extracellular concentration of glutamate in the brain ([Glu]e) were monitored continuously by an enzyme-amperometric technique employing a dialysis electrode during ischemia caused by isolation of the brain tissue in rats and human patients. In the rat (n = 10), the dialysis electrode was placed in the frontal cortex and the frontal lobe was transected. A transient sharp increase in [Glu]e was frequently observed during the transection. A biphasic elevation (a rapid increase followed by a slowly continuing increase) subsequently occurred with a latent period of 1-3 min after the transection of the rat frontal lobe. In patients (n = 7), the dialysis electrode was placed in tumor-free cortical areas which were planned to be resected together with gliomas. Progressive increases in [Glu]e were observed in all of the patients as the isolation of the brain tissue progressed. A biphasic increase, similar to that seen in the rat, was identified in 2 patients in whom the cortical area surrounding the dialysis electrode was rapidly isolated. The present enzyme-amperometric technique employing a dialysis electrode appears to be useful for detecting the occurrence of potentially harmful ischemia and for securing minimal metabolic stress caused during various surgical manipulations.

Animals↗
PubMed1999

Preserved benzodiazepine receptors in Alzheimer's disease measured with C-11 flumazenil PET and I-123 iomazenil SPECT in comparison with CBF.

This study evaluates the regional cerebral blood flow (CBF) with H2(15)O-PET and the distribution of central benzodiazepine receptor (BZR) with C-11 flumazenil (FMZ) by PET and I-123 iomazenil (IMZ) by SPECT in Alzheimer's disease (AD). In AD, whereas the CBF was diminished in the frontal, temporal, parietal, and occipital cortex, the distribution volume of FMZ and delayed activity of IMZ were relatively preserved in these cortices, suggesting that the BZR reduction, reflecting neuronal loss, is less prominent than the CBF suppression. The mini-mental state examination score (MMS) was weakly correlated with the CBF in the parietal cortex but not with BZR. It is speculated that the neuronal density reflected by BZR is less impaired than the neuronal function assessed with blood flow in the association cortex of AD. High correlation was found between the uptake of FMZ and the delayed activity of IMZ. The delayed image of IMZ-SPECT is clinically useful to evaluate the preservation of neuronal density in the affected temoporoparietal association cortex in AD.

Aged↗
PubMed1999

Benzodiazepine receptor imaging with iomazenil SPECT in aphasic patients with cerebral infarction.

To investigate the relationship between prognosis of aphasia and neuronal damage in the cerebral cortex, we evaluated the distribution of central-type benzodiazepine receptor (BZR) binding in post-stroke aphasics with [123I]iomazenil and SPECT. We performed iomazenil SPECT in six aphasic patients (aged from 45 to 75 years; all right-handed) with unilateral left cerebral infarction. Three patients showed signs of Broca's aphasia and the other three Wernicke's aphasia. Cerebral blood flow (CBF) imaging was performed with [123I]iodoamphetamine (IMP). The regions of interest (ROIs) on both images were set in the cerebral cortex, cerebellar cortex and language-relevant area in both hemispheres. Three patients were classified in the mild prognosis group and the other three in the moderate prognosis group. The left language-relevant area was more closely concerned with the difference in aphasic symptoms than the right one in both BZR and CBF distribution, but the ipsilateral to the contralateral ratio (I/C ratio) in the language-relevant areas in the BZR distribution was significantly lower in the moderate prognosis group than in the mild prognosis group, although no difference was seen for these values between the two groups in the CBF distribution. These results suggest that BZR imaging, which makes possible an increase in neuronal cell viability in the cerebral cortex, is useful not only for clarifying the aphasic symptoms but also for evaluating the prognosis of aphasia in patients with cerebral infarction.

Aged↗
PubMed1999

Post-parturition infectious endocarditis in a patient with a normal mitral valve.

A 29-year-old woman with no history of heart disease was admitted for the treatment of congestive heart failure. Six months earlier, she had given birth, then 20 days later developed a fever and cardiac failure ensued. An echocardiogram demonstrated severe mitral valve regurgitation. Her blood cultures were positive, and we made a diagnosis of mitral valve regurgitation due to infectious endocarditis. Despite treatment for congestive heart failure and antibiotic therapy, resulting in negative blood cultures, her congestive heart failure did not improve, and vegetation on the mitral valve was observed by echocardiography. We successfully removed the infected tissue with mitral valve plasty.

Adult↗
PubMed1999

Variant Gerstmann-Sträussler syndrome with the P105L prion gene mutation: an unusual case with nigral degeneration and widespread neurofibrillary tangles.

We present here a case of variant Gerstmann-Sträussler syndrome (GSS) with a codon 105 mutation of the prion protein gene. A 57-year-old woman developed dementia and gait disturbance dissimilar to the spastic paraparesis that is observed in most cases with codon 105 mutation. The clinical course of the disease in this case was 12 years. The brain weighed 900 g, and the frontal lobe, pallidum and thalamus were markedly atrophic. Severe neuronal loss was observed in the deep layer of the frontal and temporal cortices, and fibrillary gliosis and a marked loss of neurons was observed in the globus pallidus, thalamus and substantia nigra. Many amyloid plaques and some ballooned neurons were present in the frontal, temporal and parietal cortices. However, no spongiform changes were seen. The cerebellum was relatively well preserved. Numerous neurofibrillary tangles (NFTs) were recognized in the cerebral cortices, and scattered NFTs were observed in the basal nucleus of Meynert, thalamus, substantia nigra, periaqueductal gray matter, raphe nuclei and locus ceruleus. The case presented here indicates the presence of variations in the pathological findings of cases with codon 105 mutation, and that the formation of cortical and brain stem NFTs might have something to do with the duration of illness and/or the degree of brain tissue destruction that had occurred.

Brain↗
PubMed1999

Voltage-shift of the current activation in HERG S4 mutation (R534C) in LQT2.

OBJECTIVE: Recently, a novel missense mutation (R534C) in the S4 region of human ether-a-go-go-related gene (HERG) was identified in one Japanese LQT2 family. The S4 region presumably functions as a voltage sensor. However, it has not yet been addressed whether the S4 region of HERG indeed functions as a voltage sensor, and whether these residues play any role in abnormal channel function in cardiac repolarization. METHODS: We characterized the electrophysiological properties of the R534C mutation using the heterologous expression system in Xenopus oocytes. Whole cell currents were recorded in oocytes injected with wild-type cRNA, R534C cRNA, or a combination of both. RESULTS: Clinical features--QTc intervals of all affected patients with R534C mutation in HERG are prolonged ranging from 460 to 680 ms (averaged QTc interval > 540 ms). One member of this family had experienced sudden cardiac arrest, and other suffered from recurrent palpitation. Electrophysiology--Oocytes injected with R534C cRNA did express functional channels with altered channel gating. Kinetic analyses revealed that the R534C mutation shifted the voltage-dependence of HERG channel activation to a negative direction, accelerated activation and deactivation time course, and reduced steady-state inactivation. Quantitative analyses revealed that this mutation did not cause apparent dominant-negative suppression. Computer simulation--Incorporating the kinetic alterations of R534C, however, did not reproduce prolonged action potential duration (APD). CONCLUSIONS: The data revealed that arginine at position 534 in the S4 region of HERG is indeed involved in voltage-dependence of channel activation as a voltage sensor. Our examination indicated that HERG current suppression in R534C mutation was the least severe among other mutations that have been electrophysiologically examined, while affected patients did show significant QT prolongation. This suggest that another unidentified factor(s) that prolong APD might be present.

Action Potentials↗
PubMed1999

Establishment and characterization of a novel ALL-L3 cell line (BALM-18): induction of apoptosis by anti-IgM and inhibition of apoptosis by bone marrow stroma cells.

A human acute lymphoblastic leukemia (ALL) cell line, BALM-18, was established from the peripheral blood specimen of a patient with B cell ALL L3 type (ALL-L3) at diagnosis using bone marrow stroma cells (BST) as feeder cells. The primary leukemia cells did not grow without feeder cells. As with the primary leukemia cells, BALM-18 showed an immunophenotype of Burkitt's lymphoma group I [CD10+, CD20+, CD23-, CD39-, CD77+] and carried the t(8;14)(q24;q32) chromosomal abnormality which is highly associated with ALL-L3 and Burkitt's lymphoma. It also revealed a significantly low level of bcl-2 protein. Strikingly, anti-human IgM antibody did induce apoptosis in induction experiments. However, it was reversed by the addition of anti-CD40 antibody or BST cells, whereas the culture supernatant of the stroma cells did not show any effect on the inhibition of apoptosis. BALM-18 may be useful for analyzing both the mechanisms of anti-IgM induced apoptosis and signaling during the inhibition of apoptosis by CD40 or BST cells.

Adult↗
PubMed1999

Increased intracellular Ca2+ concentration in the hippocampal CA1 area during global ischemia and reperfusion in the rat: a possible cause of delayed neuronal death.

The crucial role of free cytosolic Ca2+ in ischemic neuronal damage has been studied in recent years. In the present report, changes in the intracellular Ca2+ concentration in the hippocampal CA1 area during transient global ischemia and reperfusion were measured using in vivo Ca2+ fluorometry with fura-2 in the four-vessel occlusion and reperfusion model in halothane-anesthetized rats. Marked changes were seen during 10-min global ischemia, with the intracellular Ca2+ concentration increasing gradually following application of the ischemic insult and rapidly about 2 min after the beginning of ischemia, and continuing to increase until reperfusion. On reperfusion, the intracellular Ca2+ concentration began to decrease and returned to the pre-ischemic level within 15 min. Induction of severe global ischemia was confirmed by the complete suppression of synaptic activity and the decrease in hippocampal temperature in the CA1 area. After seven days, CA1 pyramidal cell loss was observed histopathologically in the same rats which had undergone measurement of the intracellular Ca2+ concentration changes. In the present study, a temporal profile of the free cytosolic Ca2+ dynamics during ischemic and early post-ischemic period was determined in vivo. The results demonstrate that the intracellular Ca2+ concentration in the hippocampal CA1 area is transiently and markedly increased during a brief ischemia-inducing delayed neuronal death, implying that Ca2+ overload during cerebral ischemia is a possible cause of the delayed cell death of CA1 pyramidal neurons.

Animals↗
PubMed1999

Growth cones exhibit enhanced cell-cell adhesion after neurotransmitter release.

Evoked release of acetylcholine and subsequent cell-cell adhesive contacts between growth cones and acetylcholine sensing neurons were observed using cultured neurons dissociated from the diagonal band of Broca of the rat. Stimulation to the soma of the diagonal band of Broca neurons evoked release of acetylcholine from the growth cones. The release of acetylcholine was monitored using whole-cell patch-clamp recording from acetylcholine receptor-rich superior cervical ganglion neuron positioned on the growth cone as a sensor of acetylcholine release. By measuring changes in fluorescence from the growth cone using Ca2(+)-sensitive dye while voltage-clamping the superior cervical ganglion neuron, transient intracellular Ca2+ concentration increase and acetylcholine release from growth cone were recorded simultaneously. Video-enhanced differential interference contrast imaging of the growth cones demonstrated tether formation between the growth cone and superior cervical ganglion cell soma when the superior cervical ganglion cell soma was moved away from the growth cone after acetylcholine release, suggesting formation of adhesive contacts between the growth cone and the sensor neuron. Adhesive contacts between growth cones and sensor neurons were also detected when a high K+ solution or alpha-latrotoxin was applied to the growth cone. Adhesions were also observed between growth cones and latex beads, when growth cones were exposed to high K+ solution. The properties of the adhesive contacts at the growth cone were studied by optically manipulating a latex bead attached to the growth cone surface. These results suggest that growth cones exhibit cell-cell adhesion after neurotransmitter release.

Animals↗
PubMed1999

Control of proliferation and survival of C6 glioma cells with modification of the nerve growth factor autocrine system.

Nerve growth factor (NGF) plays an important physiological role in differentiation and survival of various types of neurons. Glial cells and glial tumor cells synthesize multiple neurotrophic factors including NGF and secrete them into the surrounding environment; however, the mechanisms of NGF and the significance of NGF receptors have not been studied in detail. The C6 glioma cell line can synthesize NGF, respond to exogenous application of NGF and stimulate the expression of NGF receptor in an autocrine manner. In order to determine the significance of such an NGF autocrine system, the effects of exposure to exogenous NGF and deprivation of endogenous NGF were examined in a C6 glioma cell line in vitro. Exogenous NGF significantly inhibited maintenance of the cell number and thymidine incorporation. Morphological changes, including the formation of growth cones, outgrowth of processes and cellular hypertrophy, were observed, concurrently, indicating that exogenous NGF stimulated differentiation and thereby inhibited proliferation of the cells. Deprivation of endogenous NGF with anti-NGF antibody elicited a rapid decrease in cell number and thymidine incorporation, and led almost all of the cells to death within 8 days. The protein synthesis inhibitor, cycloheximide, strongly inhibited the death of NGF-deprived cells, suggesting the involvement of an active process requiring synthesis of suicide proteins. These findings imply that the NGF autocrine system plays a significant role in regulating the differentiation and survival of C6 glioma cells, similarly to neuronal cells.

Animals↗
PubMed1999

Hematopoietic progenitor cells from allogeneic bone marrow transplant donors circulate in the very early post-transplant period.

Despite the therapeutic efficacy of allogeneic bone marrow transplantation (allo-BMT), circulating hematopoietic progenitor cells after bone marrow transplantation have not been well characterized. In the present study, we focused on these 'post-transplant circulating progenitor cells (PTCPC)' which may be on their way to bone marrow. We analyzed the number of myeloid progenitor cells (CFU-GM) per 10 ml of peripheral blood (PB) on days 0 (just before transplantation), 1 (8-15 h after the completion of transplantation), 2, 3, 5, 7, 10, 14, 17, 21, 28 and 35 after allo-BMT in five transplant patients using a standard methylcellulose assay. In addition, high proliferative potential colony-forming cells (HPP-CFC) of the harvested donor bone marrow (BM) and day 1 PB of recipients were assayed in five patients. The origin of HPP-CFC from day 1 PB was analyzed by polymerase chain reaction of a DNA region containing a variable number of tandem repeats. The replating potential of these HPP-CFC was evaluated by a secondary colony assay. The proportion of CD38negative cells among CD34+ cells in the harvested BM and day 1 PB was evaluated by two-color flow cytometric analysis. The number of CFU-GM on day 1 ranged from 6 to 73/10 ml PB, and became undetectable on day 5. The reappearance of PTCPC was observed on day 14, along with hematopoietic recovery. The proportion of HPP-CFC among myeloid colonies from day 1 PB was significantly higher than that from harvested BM (44.3+/-10.4% vs 11.3+/-2.1%, respectively, n=5, P=0.0030). These HPP-CFC from day 1 PB were confirmed to be of donor origin. More than 90% of these HPP-CFC had replating potential. Two-color flow cytometric analysis revealed that the proportion of CD34+CD38negative cells was significantly higher in day 1 PB than in the harvested BM (61.0+/-16.5% vs 9.3+/-3.5%, respectively, n=7, P=0.0002). These observations suggest that both primitive and committed transplanted myeloid progenitor cells may circulate in the very early period following allo-BMT.

ADP-ribosyl Cyclase↗
PubMed1999

Characterization of Sphingomonas paucimobilis SYK-6 genes involved in degradation of lignin-related compounds.

Sphingomonas paucimobilis SYK-6 is able to grow on a wide variety of dimeric lignin compounds. These compounds are degraded via vanillate and syringate by a unique enzymatic system, composed of etherases, O demethylases, ring cleavage oxygenases and side chain cleaving enzymes. These unique and specific lignin modification enzymes are thought to be powerful tools for utilization of the most abundant aromatic biomass, lignin. Here, we focus on the genes and enzymes involved in beta-aryl ether cleavage and biphenyl degradation. Two unique etherases are involved in the reductive cleavage of beta-aryl ether. These two etherases have amino acid sequence similarity with the glutathione S-transferases, and use glutathione as a hydrogen donor. It was found that 5,5'-dehydrodivanillate, which is a typical lignin-related biphenyl structure, was transformed into 5-carboxyvanillate by the reaction sequence of O-demethylation, meta-ring cleavage, and hydrolysis, and the genes involved in the latter two reactions have been characterized. Vanillate and syringate are the most common intermediate metabolites in lignin catabolism. These compounds are initially O-demethylated and the resulting diol compounds, protocatechuate (PCA) and 3-O-methylgallate, respectively, are subjected to ring cleavage catalyzed by PCA 4,5-dioxygenase. The ring cleavage products generated are further degraded through the PCA 4,5-cleavage pathway. We have isolated and characterized genes for enzymes involved in this pathway. Disruption of a gene for 2-pyrone-4,6-dicarboxylate hydrolase (ligI) in this pathway suggested that an alternative route for 3-O-methylgallate degradation, in which ligI is not involved, would play a role in syringate catabolism. In this article, we describe the genetic and biochemical features of the S. paucimobilis SYK-6 genes involved in degradation of lignin-related compounds. A possible application of the SYK-6 lignin degradation system to produce a valuable chemical material is also described.

Journal Article↗
PubMed1999

Mucinous carcinoma of the breast: a multifaceted study with special reference to histogenesis and neuroendocrine differentiation.

Although mucinous carcinoma (MC) of the breast is considered to originate from ductal carcinoma, it is not known whether mucinous growth begins in the intraductal carcinoma or later in the invasive carcinoma. In this study, 33 MC (16 pure without any ductal components, 10 mixed Type I with an intraductal component, seven mixed Type II with a common invasive ductal carcinoma (IDC) component)) were examined to clarify the time when mucinous growth begins. Histochemical and immunohistochemical examinations of mucin revealed that mucinous growth can begin in the intraductal carcinoma and in the common IDC. Histological transition and clonality analysis using microsatellite markers supported that some MC originate from common IDC. The pure type of MC probably originates from the intraductal carcinoma, showing a micropapillary feature. Neuroendocrine differentiation, known to be associated with MC, seemed to create the main progress in the typical MC. Moreover, we analyzed the factors of a worse prognosis of mixed MC Type II, which was strongly suggested by the lymph node status. However, no explainable differences on the cell proliferating ability, or c-erbB-2 and p53 protein overexpression were found.

Adenocarcinoma, Mucinous↗
PubMed1999

A re-evaluation of the taxonomy of Paracoccus denitrificans and a proposal for the combination Paracoccus pantotrophus comb. nov.

Comparison of both 16S rRNA coding sequences and DNA-DNA hybridization of ten strains of alpha-subclass of Proteobacteria currently classified as strains of Paracoccus denitrificans has shown that they fall into two groups which are distinct from each other at the species level. Comparison with published data on the cytochrome c profiles and other 16S rRNA coding sequences in the literature has confirmed these observations and enabled several other strains also to be assigned to these two groups. Group A comprises strains ATCC 17741T (the type strain of P. denitrificans), LMD 22.21T, DSM 413T, ATCC 19367, ATCC 13543, DSM 1404, DSM 1405, Pd 1222 (a genetic modification of DSM 413T) and NCIMB 8944. Group B comprises ATCC 35512T (the original type strain of Thiosphaera pantotropha), LMD 82.5T, LMD 92.63, DSM 65, LMG 4218, IAM 12479, JCM 6892, DSM 11072, DSM 11073 and DSM 11104. In light of these findings, it is proposed that: (1) strains of group A are retained as P. denitrificans, with ATCC 17741T as the type strain of the type species; and (2) all strains of group B are assigned to the new species combination Paracoccus pantotrophus comb. nov., with strain ATCC 35512T as the type strain. Comparative 16S rRNA sequence analysis and DNA-DNA hybridization of strains of Paracoccus versutus confirm that this species is distinct from both P. denitrificans and P. pantotrophus, but that its nearest phylogenetic neighbour is P. pantotrophus.

Cytochrome c Group↗
PubMed1999

Cerebellar activation during ataxic gait in olivopontocerebellar atrophy: a PET study.

OBJECTIVE: To investigate the possible abnormal regional brain metabolism during ataxic gait in olivopontocerebellar atrophy (OPCA), and to evaluate the response of the cerebellar subregions to instability during bipedal gait. MATERIAL AND METHODS: On 9 patients with OPCA in early phase and on 10 age-matched normal subjects, we performed positron emission tomography (PET) with 2-[18F]fluoro-2-deoxy-D-glucose (FDG) under two different conditions: supine resting and 30 min treadmill walking. RESULTS: Both in normals and in patients with OPCA, the FDG uptake in the walking state (Uwalk) was significantly greater than that in the resting state (Urest) in the pyramis, declive-folium-tuber and culmen of the cerebellar vermis, and in the thalamus. In the patients, the Uwalk was also significantly greater than the Urest in the posterior lobe of cerebellar hemisphere and in the pons and midbrain. In the pyramis, the activation ratio (= Uwalk/Urest) of the patients was significantly lower than that of the normals. CONCLUSIONS: We considered that these findings reflect the pathophysiology of ataxic gait in OPCA patients and the compensatory mechanism for the instability during ataxic gait.

Adult↗
PubMed1999

Cloning and nucleotide sequence determination of the entire mec DNA of pre-methicillin-resistant Staphylococcus aureus N315.

In methicillin-resistant Staphylococcus aureus, the methicillin resistance gene mecA is localized within a large chromosomal region which is absent in the methicillin-susceptible S. aureus chromosome. The region, designated mec DNA, is speculated to have originated from the genome of another bacterial species and become integrated into the chromosome of the S. aureus cell in the past. We report here cloning and determination of the structure of the entire mec DNA sequence from a Japanese S. aureus strain, N315. The mec DNA was found to be 51,669 bp long, including terminal inverted repeats of 27 bp and a characteristic pair of direct repeat sequences of 15 bp each: one is situated in the right extremity of mec DNA, and the other is situated outside the mec DNA and abuts the left boundary of mec DNA. The integration site of mec DNA was found to be located in an open reading frame (ORF) of unknown function, designated orfX. Clusters of antibiotic resistance genes were noted in mec DNA carried by transposon Tn554 and an integrated copy of plasmid pUB110. Both the transposon and plasmid were integrated in the proximity of the mecA gene, the latter being flanked by a pair of insertion sequence IS431 elements. Many ORFs other than those encoding antibiotic resistance were considered nonfunctional because of the acquired mutations or partial deletions found in the ORFs. Two ORFs potentially encoding novel site-specific recombinases were found in mec DNA. However, there was no ORF that might encode mec DNA-specific transposase or integrase proteins, indicating that the mec DNA is not a transposon or a bacteriophage in nature.

Amino Acid Sequence↗