Biomedical subjects

K Sakurai

Publications and source records attributed to K Sakurai.

At least 55 records · Page 3Linked to original sources

PubMed2001

Perceptual continuation and depth in visual phantoms can be explained by perceptual transparency.

We try to explain perceptual continuation and depth in the visual-phantom illusion in terms of perceptual transparency. Perceptual continuation of inducing gratings across the occluder in stationary phantoms could be explained with unique transparency, a notion proposed by Anderson (1997 Perception 26 419-453). This view is consistent with a number of previous reports including that of McCourt (1994 Vision Research 34 1609-1617) who criticized the stationary phantom illusion from the viewpoint of his counterphase lightness induction or grating induction, which might involve invalid transparency. Here we confirm that the photopic phantom illusion (Kitaoka et al, 1999 Perception 28 825-834) really gives in-phase lightness induction and involves bistable transparency. It is thus suggested that perceptual continuation and depth in the visual-phantom illusion depend on perceptual transparency.

Analysis of Variance↗

PubMed2001

Application of schizophyllan as a novel gene carrier.

Schizophyllan (SPG) is a kind of beta-1,3-glucan which has glucose side chain through a beta-1,6-glycosil bond (Fig. 1). It was found that SPG could form complex with single stranded polynucleotides. SPG forms triple stranded complex with single stranded RNAs thorough hydrogen bonding and hydrophobic interaction. It was found tht polynucleotide was protected from nuclease attacking to form the complex with SPG, and SPG enhanced antisense efficient.

DNA, Antisense↗

PubMed2001

A novel technique to specifically separate RNAs by Schizophyllan.

Schizophyllan (SPG) is a kind of beta-1,3-glucan which has glucose side chain through a beta-1,6-glycosil bond (Fig. 1). It was found that SPG could form complex with single stranded polynucleotides. SPG complexes with single stranded RNAs that have similar helix parameter to triple stranded SPG thorough hydrogen bonding and hydrophobic interaction. We prepared single stranded SPG appended gel supports. It worked as affinity column for polynucleotides. Poly(C) and poly(A) was retained in the SPG column at low temperature, though poly(G) passed by SPG column without interaction. RNAs trapped in the SPG appended column were released by changing elution buffer under mild condition. This SPG column could use to separation of mRNA which has poly(A) tail. The results obtained led to the conclusion that SPG which has neither cation charge or nucleic base can play as RNA separation material.

Chromatography, Affinity↗

PubMed2001

Two types of putative nuclear factors that physically interact with histidine-containing phosphotransfer (Hpt) domains, signaling mediators in His-to-Asp phosphorelay, in Arabidopsis thaliana.

The higher plant, Arabidopsis thaliana, has a large number of genes, each of which encodes a component of His-to-Asp phosphorelay signal transduction systems. One type of such signal transducers are the histidine-containing phosphotransmitters (termed AHPs), which presumably mediate His-to-Asp phosphorelay. Here we attempted to isolate a factor or factors that interact with AHP1, AHP2 and AHP3 by means of a yeast two-hybrid system. This allowed us to identify two types of nuclear-localizing proteins. They are the members of the type-B family of response regulators (specifically, ARR1, APP2 and ARR10), and a novel protein named TCP10. The binding of ARR1 to AHP2 was also confirmed by in vitro binding assays. Moreover, dephosphorylation of AHP2 was observed in a manner dependent on ARR in vitro. A subset of AHPs appeared to also interact with a protein that contains a TCP domain, a recently proposed basic helix-loop-helix motif. Because several factors carrying the TCP domain have been implicated in the regulation of growth and development in lateral organs, the binding of TCP10 to this subset of AHPs suggests a possible linkage between the His-to-Asp phosphorelay systems and plant growth regulation.

Amino Acid Sequence↗

PubMed2001

Salt-dependent monomer-dimer equilibrium of bovine beta-lactoglobulin at pH 3.

Although bovine beta-lactoglobulin assumes a monomeric native structure at pH 3 in the absence of salt, the addition of salts stabilizes the dimer. Thermodynamics of the monomer-dimer equilibrium dependent on the salt concentration were studied by sedimentation equilibrium. The addition of NaCl, KCl, or guanidine hydrochloride below 1 M stabilized the dimer in a similar manner. On the other hand, NaClO(4) was more effective than other salts by about 20-fold, suggesting that anion binding is responsible for the salt-induced dimer formation, as observed for acid-unfolded proteins. The addition of guanidine hydrochloride at 5 M dissociated the dimer into monomers because of the denaturation of protein structure. In the presence of either NaCl or NaClO(4), the dimerization constant decreased with an increase in temperature, indicating that the enthalpy change (DeltaH(D)) of dimer formation is negative. The heat effect of the dimer formation was directly measured with an isothermal titration calorimeter by titrating the monomeric beta-lactoglobulin at pH 3.0 with NaClO(4). The net heat effects after subtraction of the heat of salt dilution, corresponding to DeltaH(D), were negative, and were consistent with those obtained by the sedimentation equilibrium. From the dependence of dimerization constant on temperature measured by sedimentation equilibrium, we estimated the DeltaH(D) value at 20 degrees C and the heat capacity change (DeltaC(p)) of dimer formation. In both NaCl and NaClO(4), the obtained DeltaC(p) value was negative, indicating the dominant role of burial of the hydrophobic surfaces upon dimer formation. The observed DeltaC(p) values were consistent with the calculated value from the X-ray dimeric structure using a method of accessible surface area. These results indicated that monomer-dimer equilibrium of beta-lactoglobulin at pH 3 is determined by a subtle balance of hydrophobic and electrostatic effects, which are modulated by the addition of salts or by changes in temperature.

Animals↗

PubMed2001

Inotropic response of rabbit ventricular myocytes to endothelin-1: difference from isolated papillary muscles.

Endothelin-1 (ET-1) increased cell shortening and Ca2+ transients over the concentration of 3 x 10(-11) M to 10(-9) M with EC50 of 8.3 x 10(-11) M in rabbit single ventricular myocytes. Thus ET-1 was approximately 60 times more potent in single myocytes than in papillary muscles (EC50 = 5.1 x 10(-9) M) of the same species. In single myocytes, ET-1 at 10(-8) M elicited an inhibitory response that counteracted the facilitatory response: the concentration-response curve (CRC) for ET-1 was bell shaped. The ET(A)-receptor antagonist BQ-485 shifted CRC for ET-1 to the right in parallel; however, the facilitatory response to 10(-8) M ET-1 was markedly enhanced by BQ-485 and also by the ET(B) antagonist BQ-788. The ET(A)/ET(B) antagonist TAK-044 abolished the ET-1-induced response. These findings indicate that the response to ET-1 of single myocytes is different from that of papillary muscles in concentration dependence, characteristics of the response, and susceptibility to ET-receptor antagonists. Anomalous pharmacological characteristics of ET-1-induced response in rabbit papillary muscles may be due to integrated regulatory mechanisms that may involve also various types of noncardiac cell in ventricular myocardium.

Animals↗

PubMed2001

Apoptosis and mitochondrial damage in INS-1 cells treated with alloxan.

To evaluate the participation of mitochondrial damage, oxygen radicals and cell death in diabetes mellitus, we designed a way to investigate INS-1 cells, rat pancreatic beta-cell line, to die by treatment with alloxan which generate reactive oxygen species (ROS). Incubation of INS-1 cells with alloxan for 24 h resulted in a decrease in viability of cells as well as inhibition of glucose-stimulated insulin release; this could be prevented by antioxidants, vitamin E and butylated hydroxyanisol (BHA). The formation of a DNA ladder and the distribution of phosphatidylserine at the external surface of plasma membrane were observed as indicators of apoptosis in the cells treated with alloxan at concentrations below 0.5 mM. The formation of DNA ladder was prevented by vitamin E, BHA and catalase, suggesting that the ROS is involved in the process of apoptosis in INS-1 cells treated with alloxan. Lower levels of intracellular ATP, collapse of mitochondrial membrane potential and release of cytochrome c from mitochondria were also observed in INS-1 cells treated with alloxan, suggesting that alloxan caused the damage of mitochondria in cells and was related to the process of apoptosis. In contrast, rat liver RLC-18 cells treated with alloxan were not observed in the decrease of viability. It follows from the present study that mitochondrial damages by ROS generated from alloxan is linked to apoptosis in INS-1 cells.

Adenosine Triphosphate↗

PubMed2001

Spectral characteristics of human atrial fibrillation waves of the right atrial free wall with respect to the duration of atrial fibrillation and effect of class I antiarrhythmic drugs.

The aim of this study was to use fast Fourier transform analysis to clarify the characteristics of human atrial fibrillation (AF) waves with respect to the duration of AF and the effect of class I antiarrhythmic drugs. Twenty-two patients (10 paroxysmal AF, 12 persistent AF) without organic heart disease were studied by conventional electrophysiological methods. Electrograms were recorded from the right atrial free wall during AF and spectral analysis was performed for 35s (16 consecutive 4096-ms epochs with 50% overlap) and the fibrillation cycle length (FCL) was calculated from the peak frequency. Mean FCL and SD were determined from 16-epoch data, and the temporal variability of FCL was defined as the SD of FCL. Paroxysmal AF had a longer mean FCL than persistent AF (178+/-26ms vs 139+/-16 ms, p<0.001) and AF duration had a significant inverse correlation with mean FCL (r=-0.79, p<0.001). The temporal variability of FCL was significantly greater in paroxysmal AF than in persistent AF (p<0.05) and there was a significant positive correlation between the mean FCL and the temporal variability of FCL (r=0.66, p<0.001). In 8 of 18 patients given a class I antiarrhythmic drug (cibenzoline or procainamide), AF was terminated and in those patients the mean FCLs before administration of class I drugs were significantly greater than in patients without AF termination. With respect to mean FCL before drug administration, conversion occurred in 100% of patients with FCL > or =168 ms and in 17% of those with FCL <168 ms. A longer duration of AF shortens the mean FCL, which is consistent with atrial electrical remodeling. Class I drugs prolong the mean FCL above a critical level and will terminate AF, which can be estimated from the mean FCL before drug administration.

Adult↗

PubMed2001

Neonatal exposure to genistein reduces expression of estrogen receptor alpha and androgen receptor in testes of adult mice.

We investigated the long-term estrogenic influence of genistein on the male reproductive system in mice. Newborn ICR male mice were treated with genistein (10, 100, or 1,000 microg/mouse) for neonatal 5 days. As positive control, administration of diethylstilbestrol (0.5-50 microg/mouse) was carried out. In mice exposed to genistein,we examined weight of testes, sperm counts, sperm motility, and mRNA expression levels of estrogen receptor a (ERalpha) and androgen receptor (AR) at 4, 8 or 12 weeks after birth. Moreover, at 12 weeks of age, we evaluated protein level of ERalpha. In our conventional reproductive-toxicological study (weight of testes, sperm counts and sperm motility), neonatal transient exposure to genistein did not show adverse effects on the male reproductive system in 4, 8 or 12 week old mice. However, in mice treated with genistein mRNA expression levels of ERa and AR were reduced at 8 weeks. This reduction was recovered at 12 weeks in mice treated with a lower dose (10 microg) of genistein but not in those with higher doses (100 microg and 1,000 microg). In addition, ERa protein levels tended to decrease in 12 weeks of adulthood. Our results exhibited that the disruption of gene expression continued for long term such as 3 months after administration of genistein, even if no effect was found at conventional reproductive-toxicological level. We have shown that neonatal administration of weak estrogenic compound (genistein) affects male reproductive organs at molecular levels in adulthood.

Animals↗

PubMed2001

[Anesthetic management for thoracoscopic bullae resection using epidural anesthesia].

We report the anesthetic management for elective thoracoscopic bullae resection (TBR) using high thoracic epidural (TE) anesthesia in awake patients. Pain and cough reflex caused by the surgical procedure could be controlled well with high TE anesthesia using 20-25 ml of 2% lidocaine. Respiratory and hemodynamic conditions remained stable during the surgical procedure. High TE anesthesia using a large dose of local anesthetic is thought to be suitable for TBR.

Adult↗

PubMed2001

[Anesthetic management of a patient with a giant bulla and liver cirrhosis using a laryngeal mask airway and epidural analgesia].

A laryngeal mask airway (LMA) and epidural analgesia were used for anesthetic management of microwave coagulo-necrotic therapy for multiple hepatoma in a 76-year-old male with a giant bulla and liver cirrhosis. Since bleeding times, PT and APTT were within normal limits, an epidural catheter was inserted between Th9 and 10 interspaces in operating room. After preoxygenation, general anesthesia was induced with propofol 120 mg. After insertion of a LMA, anesthesia was maintained under spontaneous breathing with sevoflurane (1-1.5%) in about 45% oxygen and nitrogen. During the operation, 2% lidocaine was injected continuously into the epidural space. Continuous epidural injection of 2% lidocaine was found to be very effective for obtaining abdominal muscle relaxation and perioperative pain management. Postoperative chest X ray did not show any signs of rupture of the giant bulla, and any neurological abnormalities due to the epidural hematoma were not encountered. We could reduce the risk of rupture of a giant bulla during general anesthesia using a LMA and epidural analgesia.

Aged↗

PubMed2001

[Effects of lumbar sympathetic ganglion block in a patient with acquired lymphangioma].

A 70-year-old woman developed lymphangioma following surgery for cervical cancer and subsequent radiotherapy. The operation was performed 12 years ago, and a swelling of lower extremities was recognized 8 years ago. Her lower extremities became greatly edematous, and leakage of lymph to the groin was observed. We performed bilateral lumbar sympathetic ganglion block. After the block, lymphedema was relieved dramatically, and the leakage of the lymph to the groin was gradually reduced. We conclude that lumbar sympathetic ganglion block may be very effective in some patients with acquired lymphangioma.

Aged↗

PubMed2000

Mutation analysis of the N-methyl-D-aspartate receptor NR1 subunit gene (GRIN1) in schizophrenia.

Dysfunction of N-methyl-D-aspartate (NMDA) type ionotropic glutamate receptors has been implicated in the etiology of schizophrenia based on psychotomimetic properties of the antagonist phencyclidine (PCP) and observation that mice expressing low levels of the N-methyl-D-aspartate receptor NR1 subunit exhibit behavioral alterations that may be ameliorated by neuroleptic drugs. Based on the hypothesis that some schizophrenic patients have functionally deficient mutation(s) of the gene encoding N-methyl-D-aspartate receptor NR1 subunit (GRIN1), we screened 48 Japanese patients with schizophrenia for mutations in the coding region of the GRIN1 gene. Four variants, IVS2-22T>C, IVS2-12G>A, IVS4-34C>T, and 1719G/A (Pro516Pro), were identified. No non-synonymous mutation was detected. No significant association was suggested by case-control comparisons. Results indicate that genomic variations of the GRIN1 gene are not likely to be involved substantially in the etiology of schizophrenia.

Adult↗

PubMed2000

Increased expression of c-erbB-3 protein and proliferating cell nuclear antigen during development of verrucous carcinoma of the oral mucosa.

BACKGROUND: The roles of c-erbB-3 gene and protein in the pathogenesis, progression, and outcome of oral carcinoma remain unknown. To determine whether c-erbB-3 expression could serve as an indicator of progression from premalignant to malignant transformation and of prognoses in patients with oral carcinoma, the authors examined the relation between the expression of c-erbB-3 protein and cell proliferation activity during the development of oral verrucous carcinoma (VC). METHODS: Immunohistochemical techniques were used to evaluate c-erbB-3 protein and proliferative cell nuclear antigen (PCNA). Sixty-one samples (36 patients) of verrucous hyperplasia (VH), VC, and well differentiated squamous cell carcinoma arising from verrucous carcinoma (V-WSCC) in the oral mucosa were examined. RESULTS: Normal human oral mucosa showed weak c-erbB-3 immunostaining, predominantly on the epithelial surface. In contrast, 7 (39%) of 18 VHs, 25 (84%) of 31 VCs, and all (100%) of 12 V-WSCCs demonstrated overexpression of c-erbB-3 protein with increased expression of PCNA in some premalignant epithelial cells and many tumor cells. This finding suggested the involvement of c-erbB-3 gene in the progression from VH to VC and V-WSCC. CONCLUSIONS: Overexpression of c-erbB-3 protein correlated with increased PCNA labeling index, indicating that c-erbB-3 may contribute to malignant transformation and tumor growth. Further, patients with high expression of both c-erbB-3 and PCNA had a poor outcome. Study results suggested that c-erbB-3 expression was an index of malignancy during progression from VH to VC and V-WSCC and might have been involved in the outcome of oral carcinoma patients.

Carcinoma, Verrucous↗

PubMed2000

Narrative approach to ethics education for students without clinical experience.

Niigata University School of Medicine has provided three courses in which medical ethics (ME) is taught to students who have little or no clinical experience. To evoke student's imagination, we have developed a "narrative approach" to learn ME using cases. Prior to a case analysis, students are required to exchange their own life history regarding the core issues in the case. A case is presented not only in the traditional form of vignette, but also in the form of narrative. In the narrative, the case is a story composed of personal narratives, collected and edited from diaries, letters, interviews of persons involved. Our experience suggests that the principle-based reasoning using simple vignettes is often hardly accomplished by students. However, the narrative approach was found to be useful since students can: (1) gain more accurate and wide comprehension of medical and psycho-social aspects of the case; (2) grasp the nature and the history of the conflicting views among persons in the case; (3) find more easily any method for dealing with and settling problems; and (4) exchange viewpoints with patients and their family.

Autobiographies as Topic↗

PubMed2000

Association of disease with isolation and virulence of Rhodococcus equi from farm soil and foals with pneumonia.

OBJECTIVE: To determine whether isolation and virulence of Rhodococcus equi from soil and infected foals are associated with clinical disease. DESIGN: Cross-sectional and case-control study. SAMPLE POPULATION: R equi isolates from 50 foals with pneumonia and soil samples from 33 farms with and 33 farms without a history of R equi infection (affected and control, respectively). PROCEDURE: R equi was selectively isolated from soil samples. Soil and clinical isolates were evaluated for virulence-associated protein antigen plasmids (VapA-P) and resistance to the beta-lactam antibiotics penicillin G and cephalothin. Microbiologic cultures and VapA-P assays were performed at 2 independent laboratories. RESULTS: VapA-P was detected in 49 of 50 (98%) clinical isolates; there was complete agreement between laboratories. Rhodococcus equi was isolated from soil on 28 of 33 (84.8%) affected farms and 24 of 33 (72.7%) control farms, but there was poor agreement between laboratories. Virulence-associated protein antigen plasmids were detected on 14 of 66 (21.2%) farms by either laboratory, but results agreed for only 1 of the 14 VapA-P-positive farms. We did not detect significant associations between disease status and isolation of R equi from soil, detection of VapA-P in soil isolates, or resistance of soil isolates to beta-lactam antibiotics. No association between beta-lactam antibiotic resistance and presence of VapA-P was detected. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of soil microbiologic culture and VapA-P assay results, it is not possible to determine whether foals on a given farm are at increased risk of developing disease caused by R equi.

Actinomycetales Infections↗

PubMed2000

Effects of lipid-derivatized glycosaminoglycans (GAGs), a novel probe for functional analyses of GAGs, on cell-to-substratum adhesion and neurite elongation in primary cultures of fetal rat hippocampal neurons.

The effects of glycosaminoglycans (GAG) on cell-to-substratum adhesion and neurite elongation were examined in primary cultures of fetal rat hippocampal neurons using tissue culture dishes coated with GAGs coupled to dipalmitoylphosphatidylethanolamine (PE), a novel probe for biological functions of GAGs. Both chondroitin sulfate conjugate to PE (CS-PE) and hyaluronic acid conjugate to PE (HA-PE) promoted neurite elongation from neurons in a dose-dependent manner when immobilized onto polylysine-coated dishes at various concentrations up to 1.0 microg/ml. The coating of CS-PE or HA-PE at a concentration higher than 1.0 microg/ml resulted in failure of neurite extension and adhesion of neurons to the substrata. In contrast, heparin conjugate to PE (HP-PE) did not exert any effects on neurite elongation or on cell attachment at these concentrations. These findings suggest that GAGs serve as a modulator for neurite elongation during neuronal network formation in the developing central nervous system.

Animals↗

PubMed2000

Trace chemical characterization using monochromatic X-ray undulator radiation

An efficient Johansson-type X-ray fluorescence spectrometer has been developed for advanced X-ray spectroscopic analysis with third-generation synchrotron radiation. Kalpha and Kbeta X-ray fluorescence spectra for trace metals have been collected by a Ge(220) analyzing crystal with a Rowland radius of 150 mm, under monochromatic X-ray excitation at the undulator beamline at the SPring-8. The energy resolution is approximately 10 eV for most of the K lines for 3d transition metals. In light of the greatly improved efficiency, as well as the excellent signal-to-background ratio, the relative and absolute detection limits achieved are 1 ppm and 1.2 ng of copper in a carbon matrix, respectively. The energy resolution of the present spectrometer permits the observation of some chemical effects in Kbeta spectra. It has been demonstrated that the changes in Kbeta5 and Kbeta'' intensity for iron and cobalt compounds can be used for the analysis of chemical states. Resonant X-ray fluorescent spectra are another important application of monochromatic excitation. In view of trace chemical characterization, the present spectrometer can be a good alternative to a conventional Si(Li) detector system when combined with highly brilliant X-rays.

Journal Article↗