Biomedical subjects

M Inagaki

Publications and source records attributed to M Inagaki.

At least 37 records · Page 2Linked to original sources

PubMed2001

Mechanism of hyperploid cell formation induced by microtubule inhibiting drug in glioma cell lines.

Checkpoint mechanism plays a crucial role in ensuring genomic integrity during cell cycle. Loss of checkpoint function is known to induce genomic instability and to alter ploidy of dividing cells. In this study, we examined mechanisms of hyperploid formation in glioma cells by treatment with nocodazole, which activates spindle assembly checkpoint by inhibiting microtubule polymerization. By prolonged nocodazole treatment, U251MG human glioma cell, which has a p53 mutation, underwent transient arrest at mitosis, and subsequently exited from mitotic arrest (termed 'mitotic slippage') followed by DNA replication without cytokinesis, resulting in hyperploid formation. Additionally, the heterogeneity in the number of centrosomes per cell increased during the hyperploid formation, suggesting that these hyperploid cells have genomic instability. By employing LN382 glioma cell that has a temperature-sensitive p53 mutation, we found that the activation of p53 prevents hyperploid formation after the prolonged nocodazole treatment. Furthermore, staurosporine, an inhibitor for a broad range of serine/threonine kinases including cdc2, was found to enhance hyperploid formation in U251MG cells by accelerating the induction of mitotic slippage. Interestingly, inhibitors specific for cdc2 kinase prevented the G2 to M transition but did not accelerate mitotic slippage, suggesting that staurosporine-sensitive kinases other than cdc2 are required for maintenance of spindle assembly checkpoint. Moreover, the enhancement of hyperploid formation by staurosporine was also blocked by p53-dependent G1 checkpoint. These results suggest that abrogation of G1 checkpoint is a critical factor for formation of hyperploid cells after the mitotic slippage.

CDC2 Protein Kinase↗

PubMed2001

MAP kinases mediate UVB-induced phosphorylation of histone H3 at serine 28.

Histone H3 phosphorylation is related closely to chromatin remodeling and chromosome condensation. H3 phosphorylation at serine 28 is coupled with mitotic chromosome condensation in diverse mammalian cell lines. However, the pathway that mediates phosphorylation of H3 at serine 28 is unknown. In the present study, ERK1, ERK2, or p38 kinase strongly phosphorylated H3 at serine 28 in vitro. JNK1 or JNK2 was able also to phosphorylate H3 at serine 28 in vitro but to a lesser degree. UVB irradiation markedly induced phosphorylation of H3 at serine 28 in JB6 Cl 41 cells. PD 98059, a MEK1 inhibitor, and SB 202190, a p38 kinase inhibitor, efficiently repressed UVB-induced H3 phosphorylation at serine 28. Expression of dominant negative mutant (DNM) ERK2 in JB6 Cl 41 cells totally blocked UVB-induced phosphorylation of H3 at serine 28. Additionally, DNM p38 kinase or DNM JNK1 partially blocked UVB-induced H3 phosphorylation at serine 28. Furthermore, UVB-induced H3 phosphorylation at serine 28 was inhibited in Jnk1(-/-) cells but not in Jnk2(-/-) cells. These results suggest that UVB-induced H3 phosphorylation at serine 28 may be mediated by mitogen-activated protein kinases.

Animals↗

PubMed2001

Immunohistochemical localization of phosphorylated glial fibrillary acidic protein in the prefrontal cortex and hippocampus from patients with schizophrenia, bipolar disorder, and depression.

Increasingly, abnormalities of glial cell function have been implicated in pathological studies of the major mental illnesses (schizophrenia, bipolar disorder, and major depression). In a recent proteomic study, four isoforms of astrocytic glial fibrillary acidic protein (GFAP) were decreased in one or more of these diseases. In the current study, we sought to determine the immunohistochemical localization of phosphorylated GFAP (pGFAP) in the prefrontal cortex and hippocampus and to describe possible disease-related changes in the distribution of pGFAP containing astrocytes. In the prefrontal cortex, interlaminar astrocytes in layer I and stellate astrocytes in layers II and VI were labeled. Labeled cells were also present adjacent to blood vessels in the gyral white matter and in underlying white matter generally. In the hippocampus, labeled cells were present in the polymorphic layer of the dentate gyrus. In the prefrontal cortex, schizophrenia and major depression were characterized by decreased labeling of astrocytes adjacent to blood vessels. There were no significant differences between the diagnostic groups in the other prefrontal layers or in the hippocampus. These results suggest that reduced numbers or functional regulation of pGFAP containing astrocytes occurs in schizophrenia and major depression. The mechanism by which this deficit occurs is not known, but it may adversely effect the regulation of neuronal metabolism, communication, and response to injury.

Adult↗

PubMed2001

Cold lability of lactate dehydrogenase isoenzymes and the effective preparation of reference material for clinical laboratory use.

To evaluate the storage of samples and enzyme reference materials, and to improve the commutability for inter-laboratory surveillance of activity values of lactate dehydrogenase (LD; EC 1.1.1.27) in clinical laboratory medicine and in animal veterinary medicine, we studied the electrophoretic patterns and cold lability of LD isoenzymes from tissue sources of some common vertebrate species and also from human serum sources. Among many isoenzymes from these sources, only rat LD fractions showed similar electrophoretic patterns to those of human sera, and rat LD-1 fraction was relatively cold-stable. Total LD and isoenzyme LD-1 activities in routine laboratory samples and quality-control sera were measured using eight kinds of commercially available LD assay kit, including lactate and pyruvate substrate systems. Coefficients of variation between these assay kits were markedly reduced when the activities were calculated using the partially purified rat LD-1 fraction as an enzyme reference material, compared with the activities calculated using the factor indicated in each assay kit. In the regression analysis, the intercept and slope were calculated for the regression equations obtained from 12 pairs of these assay kits. The values obtained from a small amount of human serum and control serum samples were within the 95% confidence regions of those from larger amounts of human serum samples by using the present rat LD-1 standard for measuring LD-1 activities with lactate substrate. It was evident that a cold-stable and homogeneous LD isoenzyme as an enzyme reference material might contribute to accurate measurement of activities in heterogeneous samples for inter-laboratory quality-assurance surveys in both human and animal clinical laboratory use.

Animals↗

PubMed2001

A decade of site- and phosphorylation state-specific antibodies: recent advances in studies of spatiotemporal protein phosphorylation.

From 1990 to 2001, numerous site- and phosphorylation state-specific antibodies have been developed and many are now commercially available. These antibodies have facilitated understanding of the cytoskeletal organization, signal transduction and transcriptional mechanisms as well as clinical diseases. This review is an attempt to cover all these aspects.

Animals↗

PubMed2001

Electroporation in a model of cardiac defibrillation.

INTRODUCTION: It is known that high-strength shock disrupts the lipid matrix of the myocardial cell membrane and forms reversible aqueous pores across the membrane. This process is known as "electroporation." However, it remains unclear whether electroporation contributes to the mechanism of ventricular defibrillation. The aim of this computer simulation study was to examine the possible role of electroporation in the success of defibrillation shock. METHODS AND RESULTS: Using a modified Luo-Rudy-1 model, we simulated two-dimensional myocardial tissue with a homogeneous bidomain nature and unequal anisotropy ratios. Spiral waves were induced by the S1-S2 method. Next, monophasic defibrillation shocks were delivered externally via two line electrodes. For nonelectroporating tissue, termination of ongoing fibrillation succeeded; however, new spiral waves were initiated, even with high-strength shock (24 V/cm). For electroporating tissue, high-strength shock (24 V/cm) was sufficient to extinguish ongoing fibrillation and did not initiate any new spiral waves. Weak shock (16 to 20 V/cm) also extinguished ongoing fibrillation; however, in contrast to the high-strength shock, new spiral waves were initiated. Success in defibrillation depended on the occurrence of electroporation-mediated anodal-break excitation from the physical anode and the virtual anode. Some excitation wavefronts following electrical shock used a deexcited area with recovered excitability as a pass-through point; therefore, electroporation-mediated anodal-break excitation is necessary to block out the pass-through point, resulting in successful defibrillation. CONCLUSION: The electroporation-mediated anodal-break excitation mechanism may play an important role in electrical defibrillation.

Action Potentials↗

PubMed2001

Dehydroascorbic acid and oxidative stress in haemodialysis patients.

BACKGROUND: The amount of dehydroascorbic acid contained within total ascorbic acid (oxidized as well as non-oxidized forms) in plasma, hereafter referred to as the dehydroascorbic acid fraction, may be a measure of oxidative stress during haemodialysis. In the present study, we determined this fraction in chronic haemodialysis patients. METHODS: Using high performance liquid chromatography, dehydroascorbic acid and total ascorbic acid levels were measured in 80 maintenance haemodialysis patients for a period of > 2 years as well as in 49 controls, to examine a possible association of these compounds with clinical parameters and/or drugs taken by the patients. RESULTS: Dialysis patients who had an increased plasma urate level (P < 0.05) and had been taking allopurinol (P < 0.05) or NSAID (non-steroid anti-inflammatory drugs) (P < 0.01), and dialysis patients who were younger (< or = 55 years), as compared with older dialysis patients (P < 0.01), were found to have a lower dehydroascorbic acid fraction by multivariate analysis. Mean plasma dehydroascorbic acid levels and dehydroascorbic acid fractions were significantly lower in the younger haemodialysis patients (4.8 +/- 0.7 micromol/l and 28.4 +/- 3.9%) than in healthy younger controls (13.3 +/- 1.1 micromol/l and 41.1 +/- 1.8%) (P < 0.0001 and P < 0.01, respectively). Moreover, a correlation was found between plasma dehydroascorbic acid fraction and plasma lipid peroxide (r = 0.66, P < 0.01) in patients who had not been taking allopurinol and/or NSAID. CONCLUSION: We found that dehydroascorbic acid fraction was related to patients' age, plasma urate level and to taking allopurinol or NSAID. Dehydroascorbic acid fraction may be another indirect index of oxidative stress.

Aging↗

PubMed2001

Successfully resected hepatoblastoma in a young adult with chronic hepatitis B: report of a case.

Hepatoblastoma usually occurs in children, but a few cases have also been reported in adults. We report the unusual case of hepatoblastoma in an 18-year-old adult with chronic hepatitis B. He visited a local hospital with right upper abdominal pain. Abdominal ultrasound showed a large mass in the right lobe of his liver. He was referred to our hospital and admitted for further examination. At admission, liver function tests gave slightly elevated results (aspartate aminotransferase (AST) 103 IU/l, alanine aminotransferase (ALT) 63 IU/l). A test for hepatitis virus revealed that he was a hepatitis B surface antigen (HBsAg) carrier and had experienced seroconversion. His alpha-fetoprotein (AFP) was elevated to 1 548 000 IU/ml. Abdominal ultrasound showed a 109 x 96 x 80-mm mass with mosaic pattern in the right lobe of the liver and right portal vein thrombus. Abdominal computed tomography (CT) demonstrated a large low-density mass occupying the right lobe, with some high-density parts that showed calcification. From these results, we diagnosed hepatoblastoma in a young adult. A right lobectomy was performed. Pathological examination showed a highly differentiated hepatoblastoma. Adjuvant chemotherapy was performed with cisplatin and pirarubicin. The patient has been well and free of recurrence for 12 months, and his AFP level remains almost normal.

Adolescent↗

PubMed2001

Vagosympathetic interactions in ischemia-induced myocardial norepinephrine and acetylcholine release.

To elucidate the pathophysiological roles of vagosympathetic interactions in ischemia-induced myocardial norepinephrine (NE) and acetylcholine (ACh) release, we measured myocardial interstitial NE and ACh levels in response to a left anterior descending coronary occlusion in the following groups of anesthetized cats: intact autonomic innervation (INT, n = 7); vagotomy (VX, n = 6); local administration of atropine (Atro, n = 6); transection of the stellate ganglia (TSG, n = 5); local administration of phentolamine (Phen, n = 6); and combined vagotomy and transection of the stellate ganglia (VX+TSG, n = 5). The maximum NE release was enhanced in the VX group (141 +/- 30 nmol/l, means +/- SE, P < 0.05) compared with the INT group (61 +/- 12 nmol/l). Neither the Atro (50 +/- 24 nmol/l) nor VX+TSG groups (84 +/- 25 nmol/l) showed enhanced NE release. The maximum ACh release was unaltered in the TSG and Phen groups compared with the INT group (19 +/- 4, 18 +/- 4, and 13 +/- 3 nmol/l, respectively). These findings indicate that the cardiac vagal afferent but not efferent activity reduced the ischemia-induced myocardial NE release. In contrast, the cardiac sympathetic afferent and efferent activities played little role in the ischemia-induced myocardial ACh release.

Acetylcholine↗

PubMed2001

Differential dynamic baroreflex regulation of cardiac and renal sympathetic nerve activities.

Although regional difference in sympathetic efferent nerve activity has been well investigated, whether this regional difference exists in the dynamic baroreflex regulation of sympathetic nerve activity remains uncertain. In anesthetized, vagotomized, and aortic-denervated rabbits, we isolated carotid sinuses and randomly perturbed intracarotid sinus pressure (CSP) while simultaneously recording cardiac (CSNA) and renal sympathetic nerve activities (RSNA). The neural arc transfer function from CSP to CSNA and that from CSP to RSNA revealed high-pass characteristics. The increasing slope of the transfer gain in the frequencies between 0.03 and 0.3 Hz was significantly greater for CSNA than for RSNA (2.96 +/- 0.72 vs. 1.64 +/- 0.73 dB/octave, P < 0.01, n = 9). The difference was hardly explained by the difference in static nonlinear characteristics of CSP-CSNA and CSP-RSNA relationships or by the difference in conduction velocities in the multifiber recording. These results indicate that the central processing in the brain stem differs between CSNA and RSNA. The neural arc of the baroreflex may exert differential effects on the heart and kidney in response to dynamic baroreflex activation.

Animals↗

PubMed2001

Dynamic sympathetic control of atrioventricular conduction time and heart period.

Although power spectra of R-R and P-R intervals in response to random respiration show similar frequency distributions, the way in which dynamic sympathetic regulation contributes to such similarity remains unknown. We estimated the transfer function from sympathetic stimulation to the atrioventricular interval (AV conduction time; T(AV)) with and without constant atrial pacing in seven anesthetized cats. The transfer function from sympathetic stimulation to T(AV), except for absolute gain values, approximated a low-pass filter similar to that from sympathetic stimulation to the A-A interval (heart period; T(AA)). The 90%-rise times did not differ between the T(AA) and T(AV) step responses (32.3 +/- 1.8 vs. 29.6 +/- 3.2 s). Constant pacing augmented the T(AV) step response (-0.58 +/- 0.10 vs. -0.86 +/- 0.12 ms/Hz, P < 0.05) without affecting the 90%-rise time. These findings suggest that the dynamic characteristics of sympathetic control are similar between T(AA) and T(AV) despite the different electrophysiological mechanisms determining T(AA) and T(AV). A numerical simulation indicated that if the dynamic characteristics of the sympathetic control do not match between T(AA) and T(AV), a critical condition for initiation of reentrant tachycardia would be encountered.

Animals↗

PubMed2001

In vivo assessment of acetylcholine-releasing function at cardiac vagal nerve terminals.

We examined whether the ACh concentration measured by cardiac microdialysis provided information on left ventricular ACh levels under a variety of vagal stimulatory and modulatory conditions in anesthetized cats. Local administration of KCl (n = 5) and ouabain (n = 7) significantly increased the ACh concentration in the dialysate to 4.3 +/- 0.8 and 7.3 +/- 1.3 nmol/l, respectively, from the baseline value of 0.6 +/- 0.5 nmol/l. Intravenous administration of phenylbiguanide (n = 5) and phenylephrine (n = 6) significantly increased the ACh concentration to 5.4 +/- 0.9 and 6.0 +/- 1.5 nmol/l, respectively, suggesting that the Bezold-Jarisch and arterial baroreceptor reflexes affected myocardial ACh levels. Modulation of vagal nerve terminal function by local administration of tetrodotoxin (n = 6), hemicholinium-3 (n = 6), and vesamicol (n = 5) significantly suppressed the electrical stimulation-induced ACh release from 20.4 +/- 3.9 to 0.6 +/- 0.1, 7.2 +/- 1.9, and 2.7 +/- 0.6 nmol/l, respectively. Increasing the heart rate from 120 to 200 beats/min significantly reduced the myocardial ACh levels during electrical vagal stimulation, suggesting a heart rate-dependent washout of ACh. We conclude that ACh concentration measured by cardiac microdialysis provides information regarding ACh release and disposition under a variety of pathophysiological conditions in vivo.

Acetylcholine↗

PubMed2001

Constituents of ophiuroidea. 1. Isolation and structure of three ganglioside molecular species from the brittle star Ophiocoma scolopendrina.

Three ganglioside molecular species, OSG-0 (1), OSG-1 (2), and OSG-2 (3) have been obtained from the polar lipid fraction of the chloroform/methanol extract of the brittle star Ophiocoma scolopendrina. The structures of these gangliosides have been determined on the basis of chemical and spectroscopic evidence as 1-O-[(N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (1), 1-O-[8-O-sulfo-(N-acetyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyll-ceramide (2) and 1-O-[(N-glycolyl-alpha-D-neuraminosyl)-(2-->8)-(N-acetyl- and N-glycolyl-alpha-D-neuraminosyl)-(2-->6)-beta-D-glucopyranosyl]-ceramide (3). The ceramide moieties were composed of heterogeneous unsubstituted fatty acid, 2-hydroxy fatty acid and phytosphingosine units. Compounds 2 and 3 represent new ganglioside molecular species.

Animals↗

PubMed2001

Constituents of crinoidea. 2. Isolation and structure of the novel type gangliosides from the feather star Comanthus japonica.

Two novel type gangliosides CJP2 and CJP3 have been obtained from the feather star Comanthus japonica. On the basis of methylation linkage analysis combined with ammonolysis and other chemical and spectroscopic evidence, the chemical structures of CJP2 and CJP3 were determined to be alpha-9-O-Me-NeuGc-(2-->3)-inositolphosphoceramide and alpha-9-O-Me-NeuGc-(2-->11)-alpha-9-O-Me-NeuGc-(2-->3)-inositolphosphoceramide, respectively. These gangliosides are unique in that they are inositolphosphoceramide derivatives possessing sialic acid; such gangliosides have not previously been identified. The presence of 9-O-methyl-N-glycolyl-neuraminosyl residues is also unique in naturally occurring gangliosides.

Animals↗

PubMed2001

Prognostic significance of the labeling of Adnab-9 in pancreatic intraductal papillary mucinous neoplasms.

BACKGROUND: Pancreatic intraductal papillary mucinous neoplasms (IPMN), morphologically resembling colonic adenomas, often have an indefinable malignant potential. We used a monoclonal antibody (MAb) raised against colonic adenomas, Adnab-9, to identify patients with a better prognosis. METHODS: We assessed Adnab-9-labeled sections of these neoplasms from 50 patients, 13 pancreatic adenocarcinomas, and 32 colonic adenomas using standard immunohistochemical techniques. RESULTS: 26% of the IPMNs labeled with Adnab-9 as compared to 0% of pancreatic ductal cancers or surrounding benign tissues, (p < 0.001) and 53% of adenomas (p < 0.025). Labeling in IPMNs was usually seen in the noninvasive epithelium suggesting that Adnab-9 is a premalignant marker in these lesions. Labeling of invasive IPMN's identified a group of patients with a superior overall survival (p = 0.027). CONCLUSION: Adnab-9 labeling-characteristics appear similar for both IPMNs and adenomatous polyps, suggesting that they are analogous lesions. Adnab-9 labeling may also be a useful prognostic marker for invasive intraductal papillary mucinous neoplasms.

Adenocarcinoma, Mucinous↗

PubMed2001

Laterality in direct and indirect inotropic effects of sympathetic stimulation in isolated canine heart.

Although sympathetic nerve stimulation is known to increase ventricular contractility, concomitant increases in heart rate (HR) make it difficult to separate its direct inotropic effect from indirect inotropic effect through a force-frequency mechanism. We stimulated the stellate ganglia in 8 isolated canine hearts with functional sympathetic nerves. Right sympathetic stimulation at 10 Hz increased ventricular end-systolic elastance (E(es)) by 95.7 +/- 7.5% (p < 0.001) and HR by 32.5 +/- 4.2% (p < 0.05). In contrast, left sympathetic stimulation at 10 Hz increased E(es) by 70.7 +/- 6.5% (p < 0.001) without significant changes in HR. Preventing the chronotropic response by fixed-rate pacing attenuated the E(es) response to right sympathetic stimulation at 5 Hz (52.0 +/- 5.1 vs. 22.8 +/- 2.8%, p < 0.001), but not to left sympathetic stimulation at 5 Hz (54.5 +/- 3.4 vs. 53.3 +/- 2.2%, NS). In the isolated canine heart, the right sympathetic nerve affected E(es) by both the direct inotropic effect and the indirect HR-dependent inotropic effect. In contrast, the left sympathetic nerve regulated E(es) primarily by its direct inotropic effect.

Animals↗

PubMed2001

Production of recombinant human creatine kinase (r-hCK) isozymes by tandem repeat expression of M and B genes and characterization of r-hCK-MB.

BACKGROUND: Serum creatine kinase-MB isoenzyme (CK-MB) is widely used as a marker of myocardial injury. We prepared recombinant human CK (r-hCK) MB isoenzyme and examined its potential for use as a control material for assay of CK-MB in serum. METHODS: cDNAs encoding CK-M and CK-B subunits were inserted into the same plasmid vector, followed by transformation of Escherichia coli. The resulting three types of CK isoenzymes were purified by conventional chromatography. RESULTS: The ratio of MB to MM to BB was 50:40:10 on the basis of CK activity. Highly purified CK-MB with a specific activity of 533 U/mg was produced in a yield of 5.7 mg/g of packed cells. Purified r-hCK-MB had the isoelectric point (pI 5.3) and molecular size (46 kDa for the subunit) of native CK-MB. Its immunoreactivity in an ELISA using antibody against native heart enzyme was similar to that of cardiac CK-MB. The r-hCK-MB retained >90% activity for at least 4 months at 11 degrees C in a delipidated serum matrix in a liquid form at a concentration of 118 U/L. CONCLUSIONS: r-hCK-MB shows key properties of the native cardiac isoenzyme and may be useful as a control and calibrator for serum assays of CK-MB.

Creatine Kinase↗

PubMed2001

[Psycho-oncology and its scientific background].

Psycho-oncology has two purposes corresponding to the psychosocial aspects of cancer: 1. to clarify the psychosocial impacts of cancer on the quality of life of the patient, family and staff; 2. to clarify the role that psychosocial and behavioral variables may have in cancer risk and survival. For these purposes, patient education, counseling, behavioral and psychopharmacological techniques have been applied to clinical oncology. In this paper, we review psycho-oncology and its scientific background, with respect to neuroradiology and molecular genetics, as well as psychiatry, psychology, epidemiology, pharmacology and immunology.

Humans↗