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Biomedical subjects

M Sasaki

Publications and source records attributed to M Sasaki.

At least 271 records · Page 15Linked to original sources
PubMed2000

Autoepitopes on autoantigen centromere protein-A (CENP-A) are restricted to the N-terminal region, which has no homology with histone H3.

Anti-centromere autoantibodies (ACA) are commonly found in the serum of patients with a limited type of scleroderma and other systemic autoimmune diseases. CENP-A is one of the major antigens against ACA and a histone H3-like protein. To analyse the autoantigenic epitopes of CENP-A, a series of truncated peptides of human CENP-A were expressed in Escherichia coli and immunoblotting analysis was performed with 91 ACA+ sera. Eighty sera (88%) with the ACA reacted to the 52-amino acids N-terminal region which is not homologous to H3, while no sera reacted to the C-terminus which has a sequence similarity with H3. Moreover, ELISA was also employed in this study using two synthetic peptides corresponding to the amino acid sequences 3-17 (peptide A) and 25-38 (peptide B). Peptides A and B were reactive to 78 (86%) and 79 (87%) of ACA, respectively. Core antigens of hepatitis B virus (HBV) and hepatitis C virus (HCV) have similar sequences to peptide A and/or peptide B, but three sera containing HBV without ACA and five sera containing HCV without ACA were found to be reactive to neither peptide. Centromere localization of CENP-A is dependent on the H3-like C-terminal domain which is not autoantigenic, while the antigenic N-terminal domain, which might play unidentified functional roles, should be an important region for the induction of ACA.

Amino Acid Sequence↗
PubMed2000

Identification and characterization of human Wee1B, a new member of the Wee1 family of Cdk-inhibitory kinases.

BACKGROUND: In eukaryotic cells, the kinase activity of the mitosis-promoting complex composed of cyclin B and Cdc2 (Cdk1) is negatively regulated by the phosphorylation of Cdk1 on threonine or tyrosine residues within its ATP binding domain. RESULTS: We identified human Wee1B by searching a sequence database. The predicted human Wee1B protein comprises 561 amino acids. Northern blot analysis revealed that human Wee1B mRNA is particularly abundant in testis. Interestingly, RT-PCR using early embryos revealed that the Wee1B product was readily detectable at the mature oocyte, but abruptly disappeared at embryonic day 2.5, suggesting that the amount of Wee1B mRNA is dependent on the maternal expression. GFP-Wee1B showed a predominantly nuclear localization in HeLa cells. Human Wee1B was able to rescue the lethal phenotype of the fission yeast wee1-50Deltamik1 mutant, and over-expression of the human protein in these cells resulted in cell elongation as a result of arrest of the cell cycle at the G2-M transition. Recombinant Wee1B effectively phosphorylated cyclin B-associated Cdk1 on tyrosine-15, resulting in an inactivation of the kinase activity of Cdk1. CONCLUSION: We identified human Wee1B as a novel Cdk1-inhibitory kinase. The identification of this new member of the Wee1 family suggests that inhibition of Cdk1 is mediated at multiple levels in mammals.

Amino Acid Sequence↗
PubMed2000

Functional expression of mung bean Ca2+/H+ antiporter in yeast and its intracellular localization in the hypocotyl and tobacco cells.

The Ca2+-transport activity and intracellular localization of the translation product of cDNA for mung bean Ca2+/H+ antiporter (VCAX1) were examined. When the cDNA was expressed in Saccharomyces cerevisiae that lacked its own genes for vacuolar Ca2+-ATPase and the antiporter, VCAX1 complemented the active Ca2+ transporters, and the microsomal membranes from the transformant showed high activity of the Ca2+/H+ antiporter. Treatment of the vacuolar membranes with a cross-linking reagent resulted in a clear band of the dimer detected with antibody specific for VCAX1p. The antibody was also used for immunolocalization of the antiporter in fractions obtained by sucrose-density-gradient centrifugation of the microsomal fraction from mung bean. The immunostained band was detected in the vacuolar membrane fraction and the slightly heavy fractions that exhibited activity of the Golgi marker enzyme. A fusion protein of VCAX1p and green fluorescent protein was expressed in tobacco cells. The green fluorescence was clearly observed on the vacuolar membrane and, in some cases, in the small vesicles. The subcellular fractionation of transformed tobacco cells confirmed the vacuolar membrane localization of the fusion protein. These results confirm that VCAX1p functions in the vacuolar membrane as a Ca2+/H+ antiporter and also suggest that VCAX1p may exist in the Golgi apparatus.

Antiporters↗
PubMed2000

Haemorrhagic cerebral sinus thrombosis associated with ulcerative colitis: a case report of successful treatment by anticoagulant therapy.

A 29-year-old man with ulcerative colitis was admitted to our hospital because of convulsions and a headache. Before admission, oral prednisolone had been administered due to his ulcerative colitis relapse. Computed tomography revealed a low-density area in the right frontal pole suggestive of a venous infarction. Once his headache and convulsions improved after the administration of an antiepileptic drug, he began to complain of right arm numbness and right hemianopsia again. An urgent magnetic resonance imaging angiograph showed extensive thrombosis in the superior sagittal sinus. We finally used the anticoagulant agents, heparin and urokinase, which eased his complaints and prevented the development of bloody stools. He was discharged with no neurological symptoms 25 days after admission. This is a rare case of sinus thrombosis complicated by ulcerative colitis, in which anticoagulant therapy was successful. Magnetic resonance imaging angiography was useful for the diagnosis and for evaluating the therapeutic effect.

Adult↗
PubMed2000

Changes in subjective sleepiness, subjective fatigue and nocturnal sleep after anaesthesia with propofol.

The purpose of this study was to clarify the changes in psycho-physiological functions after anaesthesia with propofol (PF). The subjects were seven healthy male volunteers and the duration of the anaesthesia was 1 h (14:00-15:00 h). The plasma concentration of PF immediately decreased after the anaesthesia. The subjective sleepiness and VAS (visual liner analogue scale) scores (i.e. effort to do something) increased significantly at 20 min after the anaesthesia. However, these changes were improved at 80 min after the anaesthesia. The sleep latency at the nocturnal sleep 8 h after the anaesthesia was prolonged significantly, but the other parameters including the distributions of stage 3 + 4 and the rapid eye movement 'REM' stage were not changed.

Adult↗
PubMed2000

Sleep architectures of obstructive sleep apnea syndrome in the young child.

The sleep architectures of obstructive sleep apnea syndrome (OSAS) in the young child (child-OSAS, n = 17; mean age: 5.9+/-2.7 years; male:female 14:3) were compared with that of OSAS in the adult (n = 19; mean age: 44.7+/-10.7 years; male:female 18:1) and that of primary snoring in the child (n = 5; mean age: 7.0+/-2.4 years; male:female 5:0). Child-OSAS and OSAS in the adult had the same severity in oxygen desaturation. Child-OSAS showed lower Apnea-Hypopnea Index compared with OSAS in the adult. Sleep continuity in child-OSAS was not impaired compared with OSAS in the adult. Sleep fragmentation in child-OSAS was not so remarkable. The quantity of slow wave sleep in child-OSAS was similar to that of primary snoring in the child. Both profiles of sleep architectures showed nearly the same pattern.

Cerebral Cortex↗
PubMed2000

Effect of 3 mg melatonin on jet lag syndrome in an 8-h eastward flight.

In order to assess the effect of melatonin on jet lag a field study was undertaken. The process of re-entrainment of circadian melatonin rhythm was investigated in six subjects. Except during 24-h blood sampling, the subjects were exposed to natural zeitgeber (time giver) outdoors and given 3 mg melatonin at 23:00 h. The subjects were exposed to bright sunlight from 3000 to 12000 lx. All of them showed orthodromic re-entrainment with taking melatonin, while two out of the six did not show orthodromic re-entrainment without taking melatonin. Melatonin accelerated the rate of the re-entrainment of the circadian melatonin rhythm. Melatonin was useful to jet travel from Tokyo to Los Angeles.

Adult↗
PubMed2000

Vitamin E modified cellulose membrane.

There has been a demand for hemodialysis membranes of better biocompatibility, the use of which would reduce the incidence of complications in patients who have been under long hemodialysis treatment. We developed a surface modification technique consisting of forming efficiently a synthetic polymer layer on the inside of the regenerated cellulose hollow fiber without impairing fiber performance. Our newly developed membrane has excellent biocompatibility by modifying the inner surface and by immobilizing vitamin E (alpha-tocopherol), which serves as an antioxidant, to the modified surface.

Animals↗
PubMed2000

Destruction of bile ducts in primary biliary cirrhosis.

Primary biliary cirrhosis is characterized by the immune-mediated, progressive destruction of interlobular bile ducts. Lymphoid cells migrate into the biliary epithelial layer through integrin alpha(4)/fibronectin interaction and are responsible for chronic destructive cholangitis. The bile ducts express intercellular adhesion molecule-1 (ICAM-1) and vascular cellular adhesion molecule-1 (VCAM-1), and infiltrating lymphocytes express LFA1 and VLA4, facilitating their interaction. Epithelioid granulomas contain foamy cells ingesting biliary lipids, and CD1d was detectable in epithelioid granulomas, suggesting that the biliary substance(s) which are leaked is a trigger for chronic destructive cholangitis. Apoptotic biliary destruction is brought about by antigen-specific and non-specific reactions. Shrunken biliary epithelial cells with pyknotic nuclei positive for terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labelling (TUNEL) may reflect apoptotic processes. Increased expression of caspase-3 and -8 with DNA fragmentation factor on the bile ducts may reflect molecular events during apoptosis, and down-regulation of Bcl-2 of biliary epithelial cells seems to facilitate apoptosis. Multiple factors, particularly the Fas system, are stimuli of apoptosis. Anoikis with decreased biliary expression of integrin 6, a ligand for laminin, may also be involved in biliary epithelial apoptosis.

Apoptosis↗
PubMed2000

What are the appropriate indications for endoscopic mucosal resection for early gastric cancer? Analysis of 256 endoscopically resected lesions.

BACKGROUND AND STUDY AIMS: Although endoscopic mucosal resection (EMR) for early gastric cancer (EGC) without ulceration or scarring has been very popular in Japan and thought to be beneficial, curability by EMR is still lower than that for surgical resection. We investigated patients whose EGCs were resected endoscopically in order to identify the factors affecting curability by EMR. PATIENTS AND METHODS: We investigated retrospectively 256 EGC lesions (251 patients) which were subjected to EMR between 1989 and 1998 with respect to patient profile, macroscopic type, location, maximum diameter of tumors, resection method and histological typing. The prognoses of the patients were also investigated as far as possible. RESULTS: The curative total resection rate for EMR of EGC was 74.2 %. Concerning the factors affecting curability, the size of the lesion (over 15 mm), the method of resection (divisional resection), and histological typing (poorly differentiated) had a statistically significant effect on the complete resection rate. Multivariate analysis of the factors confirmed these results. Submucosal invasion was suspected in 16 patients after EMR, but submucosal cancer was found in only one patient after further surgery. Where there was recurrence, the longest recurrence-free period after EMR of EGC was 48 months, whereas the mean recurrence-free period was 195.4 days. CONCLUSIONS: The appropriate indication for EMR for EGC is thought to be an intramucosal differentiated-type adenocarcinoma without ulceration or scarring, and no more than 15 mm in size regardless of macroscopic type. Periodic follow-up for at least 5 years is necessary.

Adenocarcinoma↗
PubMed2000

Differential regulation of metalloproteinase production, proliferation and chemotaxis of human lung fibroblasts by PDGF, interleukin-1beta and TNF-alpha.

Fibroblast migration, proliferation, extracellular matrix protein synthesis and degradation, all of which play important roles in inflammation, are themselves induced by various growth factors and cytokines. Less is known about the interaction of these substances on lung fibroblast function in pulmonary fibrosis. The goal of this study was to investigate the effects of PDGF alone and in combination with IL-1beta and TNF-alpha on the production of human lung fibroblast matrix metalloproteinases, proliferation, and the chemotactic response. The assay for MMPs activity against FITC labeled type I and IV collagen was based on the specificity of the enzyme cleavage of collagen. Caseinolytis and gelatinolytic activities of secreted proteinases were analyzed by zymography. Fibronectin in conditioned media was measured using human lung fibronectin enzyme immunoassay. Cell proliferation was measured by 3H-Thymidine incorporation assay. Cell culture supernatants were tested for PGE2 content by ELISA. Chemotactic activity was measured using the modified Boyden chamber. Matrix metalloproteinase assay indicated that IL-1beta, TNF-alpha and PDGF induced intestitial collagenase (MMP-1) production. MMP assay also indicated that IL-1beta and TNF-alpha had inhibitory effects on MMP-2,9(gelatinaseA,B) production. Casein zymography confirmed that IL-1beta stimulated stromlysin (matrix metalloproteinase 3; MMP-3) and gelatin zymography demonstrated that TNF-alpha induced MMP-9 production in human lung fibroblast, whereas PDGF alone did not. PDGF in combination with IL-1beta and TNF-alpha induced MMP-3 and MMP-9 activity, as demonstrated by zymography. PDGF stimulated lung fibroblast proliferation in a concentration-dependent manner, whereas IL-1beta and TNF-alpha alone had no effect. In contrast, the proliferation of human lung fibroblasts by PDGF was inhibited in the presence of IL-1beta and TNF-alpha, and this inhibition was not a consequence of any elevation of PGE2. PDGF stimulated fibroblast chemotaxis in a concentration-dependent manner, and this stimulation was augmented by combining PDGF with IL-1beta and TNF-alpha. These findings suggested that PDGF differentially regulated MMPs production in combination with cytokines, and further that MMP assay and zymography had differential sensitivity for detecting MMPs. The presence of cytokines with PDGF appears to modulate the proliferation and chemotaxis of human lung fibroblasts.

Cell Division↗
PubMed2000

Effect of heparin and related glycosaminoglycan on PDGF-induced lung fibroblast proliferation, chemotactic response and matrix metalloproteinases activity.

Fibroblast migration, proliferation, extracellular matrix protein synthesis and degradation are the key events in various biological and pathological processes in pulmonary fibrosis. In addition, biopsy specimens from the lungs of patients with pulmonary fibrosis show increased numbers of mast cells which have metachromatic granules containing heparin, histamine and proteases. Little is known about how these products influence pulmonary fibrosis. In the present study, we investigated the effect of heparin and related glycosaminoglycans on PDGF-induced lung fibroblast proliferation and chemotactic response in vitro. In addition, we examined the effect of heparin on both the induction of matrix metalloproteinases (MMPs) and MMPs activity in lung fibroblasts in vitro. Heparin, de-N-sulphated heparin but not heparan sulphate inhibited PDGF-induced lung fibroblast proliferation. In contrast, only heparin inhibited PDGF-stimulated human lung fibroblast chemotaxis. Negatively charged poly-L-glutamic acid had no effect on either fibroblast proliferation or chemotaxis. Thus the negative charge alone cannot account for the ant-proliferative and anti-chemotactic effects of heparin. Furthermore, heparin and heparan sulphate also had no inhibitory effect on induction of MMPS, including MMP-1 (interstitial collagenase), MMP-2 (gelatinase A) and MMP-9 (gelatinase B). Only heparin inhibited both MMP-1 and MMP-2/MMP-9 activity. Additionally, tissue inhibitor of metalloproteinase type 1 (TIMP-1) and type 2 (TIMP-2) inhibited PDGF-stimulated human lung fibroblast chemotaxis. The ability of heparin to inhibit fibroblast chemotaxis may account for the inhibitory effect of heparin on MMP activity. The above results suggested that heparin and related glycosaminoglycans differentially regulate PDGF-induced lung fibroblast proliferation, chemotaxis and MMPs activity and further that these effects may have a key role in extracellular matrix remodeling in inflammatory lung disease.

Becaplermin↗
PubMed2000

Neuropsychological EEG activation in patients with epilepsy.

To examine the effects of higher mental activity on the EEG, 480 Japanese patients with different types of epilepsy were subjected to potentially provocative cognitive tasking, termed 'neuropsychological EEG activation' (NPA), during standard EEG recordings. NPA tasks consisted of reading, speaking, writing, written arithmetic calculation, mental arithmetic calculation and spatial construction. The NPA tasks provoked epileptic discharges in 38 patients (7.9%) and were accompanied by myoclonic seizures in 15 patients, absence seizures in eight and simple partial seizures in one. Among the cognitive tasks, mental activities mainly associated with use of the hands, i.e. writing (68.4%), written calculation (55. 3%) and spatial conction (63.2%), provoked the most discharges, followed by mental calculation (7.9%) and reading (5.3%). Detailed examination of the precipitating events revealed action-programming type activities to be the most crucial in 32 out of the 38 patients (84.2%), followed by thinking type activities in four patients (10. 5%). Regarding the classification of epilepsies proposed by the International League Against Epilepsy, seizure-precipitating mental activities in our series were almost exclusively (in 36 out of the 38 patients) related to idiopathic generalized epilepsies (IGEs) including juvenile myoclonic epilepsy, juvenile absence epilepsy, grand mal epilepsy on awakening and childhood absence epilepsy, and were rarely (in only two out of the 38 patients) related to temporal lobe epilepsy. In our IGE patients, the provocative effects of NPA were related to myoclonic seizures rather than absence or generalized tonic-clonic seizures. These results suggest that NPA is a useful tool for examining the relationship between cognitive function and epileptic seizures, and that the IGE patients with myoclonic seizures are vulnerable to higher mental activities requiring action-programming or thinking.

Adolescent↗
PubMed2000

Abnormal regional cerebral blood flow in childhood autism.

Neuroimaging studies of autism have shown abnormalities in the limbic system and cerebellar circuits and additional sites. These findings are not, however, specific or consistent enough to build up a coherent theory of the origin and nature of the brain abnormality in autistic patients. Twenty-three children with infantile autism and 26 non-autistic controls matched for IQ and age were examined using brain-perfusion single photon emission computed tomography with technetium-99m ethyl cysteinate dimer. In autistic subjects, we assessed the relationship between regional cerebral blood flow (rCBF) and symptom profiles. Images were anatomically normalized, and voxel-by-voxel analyses were performed. Decreases in rCBF in autistic patients compared with the control group were identified in the bilateral insula, superior temporal gyri and left prefrontal cortices. Analysis of the correlations between syndrome scores and rCBF revealed that each syndrome was associated with a specific pattern of perfusion in the limbic system and the medial prefrontal cortex. The results confirmed the associations of (i) impairments in communication and social interaction that are thought to be related to deficits in the theory of mind (ToM) with altered perfusion in the medial prefrontal cortex and anterior cingulate gyrus, and (ii) the obsessive desire for sameness with altered perfusion in the right medial temporal lobe. The perfusion abnormalities seem to be related to the cognitive dysfunction observed in autism, such as deficits in ToM, abnormal responses to sensory stimuli, and the obsessive desire for sameness. The perfusion patterns suggest possible locations of abnormalities of brain function underlying abnormal behaviour patterns in autistic individuals.

Adolescent↗
PubMed2000

Backbone dynamics of the c-Myb DNA-binding domain complexed with a specific DNA.

The DNA-binding domain of c-Myb consists of three imperfect tandem repeats, R1, R2, and R3. Each repeat contains three helices. The minimal DNA-binding domain is an R2R3 fragment. Here, we have examined the backbone dynamics of R2R3 in its DNA-bound form by NMR. Upon binding to DNA, the N- and C-termini, and the linker between R2 and R3 become less flexible. In the free form the third helix of R2 exhibits slow conformational exchange fluctuations owing to a cavity in the hydrophobic core of R2. Upon binding to DNA, the conformational exchange contributions in R2 are reduced but remain significant in NMR relaxation measurements. Upon binding to DNA, the third helix of R3 comes to exhibit significant chemical exchange contributions. These findings suggest that the orientations of the third helices of both R2 and R3 as to DNA are being chemically exchanged. In the DNA-bound form both R2 and R3 exhibit similar dynamical characters, except for amino acids Trp 95, Thr 96, and Val 103 of R2, which are located around the cavity of the unbound form. Upon binding to DNA, since Trp 95 moves into the cavity to fill it up, the local conformational exchange contributions seem to be still observable around the filled cavity.

Amino Acid Sequence↗
PubMed2000

Evaluation of standardized uptake value to assess cerebral glucose metabolism.

PURPOSE: When the cerebral metabolic rate of glucose (CMRglc) is to be measured, arterial blood sampling is usually required for fluorine-18 fluorodeoxyglucose (FDG) and positron emission tomography (PET) studies. However, blood sampling is inconvenient because it requires several staff members and is invasive for patients. METHODS: To assess cerebral glucose metabolism by a noninvasive and simplified method, the authors used the standardized uptake value (SUV), which requires no input function or blood sampling. The study participants included 18 healthy volunteers (4 men and 14 women; mean +/- SD age, 68.2+/-6.3 years), 18 patients with mild Alzheimer's disease (AD) (4 men and 14 women; mean +/- SD age, 68.8+/-7.3 years), and 18 patients with moderate AD (5 men and 13 women, mean +/- SD age, 69.5+/-8.5 years). Regional CMRglc and regional cerebral SUV were measured in the three groups using FDG PET, and the correlation between global CMRglc and global SUV was estimated. RESULTS: The correlation coefficients of global CMRglc and global SUV in the healthy volunteers, mild AD patients, and moderate AD patients were 0.82, 0.67, and 0.62, respectively. Compared with the healthy persons, the patients with mild AD showed significantly decreased CMRglc in the temporal, frontal, and parietal cortices, but they did not show significantly decreased SUV in any region. Patients with moderate AD had significantly decreased CMRglc in the temporal, frontal, occipital, parietal, and sensorimotor cortices and significantly decreased SUV in the temporal, frontal, occipital, and parietal cortices. CONCLUSION: The SUV would be useful as a semiquantitative index of cerebral glucose metabolism only in healthy persons or those with mild AD.

Aged↗
PubMed2000

Agonist-dependent difference in the mechanisms involved in Ca2+ sensitization of smooth muscle of porcine coronary artery.

This study was undertaken to explore possible signal-transduction mechanisms involved in the Ca2+-sensitizing effects of carbachol and endothelin-1 (ET-1) by using beta-escin-skinned smooth muscle of porcine coronary artery. Pretreatment with C3 exoenzyme of Clostridium botulinum, which selectively inactivates rho p21 by adenosine diphosphate (ADP) ribosylation, resulted in a significant inhibition of ET-1-induced Ca2+ sensitization, but had no effect on carbachol-induced Ca2+ sensitization. Whereas the protein kinase C (PKC) inhibitors calphostin C and staurosporine did not affect the Ca2+-sensitizing effect of carbachol, the tyrosine kinase inhibitors genistein and tyrphostin 25 greatly but incompletely suppressed it. In contrast, the Ca2+-sensitizing effect of ET-1 was significantly inhibited by either calphostin C or genistein. Although the inhibitory effect of calphostin C on ET-1-induced Ca2+ sensitization was less than that of genistein, the effects of calphostin C and genistein were additive. The genistein-sensitive component of ET-1-induced Ca2+ sensitization appeared to include the C3-sensitive one. However, a substantial enhancement by ET-1 of the Ca2+-induced contraction was observed even in the presence of the two inhibitors. In beta-escin-skinned smooth muscle of rabbit mesenteric artery, ET-1-induced Ca2+ sensitization was marginally affected by C3 pretreatment, calphostin C, and genistein. We conclude that, although PKC activation and rho p21 protein-dependent and -independent tyrosine phosphorylation each plays an important role in an increase in myofilament Ca2+ sensitivity, the contributions of these signaling pathways to Ca2+ sensitization are different depending on receptor agonists and tissues used. Furthermore, these data suggest the existence of an as yet undefined signal-transduction mechanism involved in Ca2+ sensitization caused by receptor agonists.

Animals↗