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K Kawano

Publications and source records attributed to K Kawano.

At least 37 records · Page 2Linked to original sources
PubMed2001

Retinotopic hemodynamic activation of the human V5/MT area during optokinetic responses.

To detect retinotopic activation in the human V5/MT, we obtained fMRI signals during optokinetic responses (OKR). We used two types of patterns, consisting of random dots plotted in either the central or peripheral regions, to stimulate the central and peripheral visual fields, respectively. These patterns moved at a constant speed of 20 degrees/s rightward and leftward alternately. Subjects were required to track the patterns with their eyes. The two types of visual stimuli elicited different patterns of brain activation; the area with the most significant response to central visual field stimuli was located posteriorly to that responding to peripheral visual field stimuli.

Adult↗
PubMed2001

Polyvalent cation-sensing mechanism increased Na(+)-independent Mg(2+) transport in renal epithelial cells.

Extracellular Ca(2+)/polyvalent cation-sensing receptor (CaSR) is capable of monitoring changes in extracellular polyvalent cation concentrations. In the present study, we investigated whether CaSR agonists reinforce the decrease of intracellular free Mg(2+) concentration ([Mg(2+)](i)) induced by extracellular Mg(2+) plus Na(+) removal. Interestingly, exposure of NRK-52E renal epithelial cells to increasing extracellular Mg(2+) concentrations from 0.8 to 15 mM for 1-2 days resulted in a twofold increase in the levels of CaSR mRNA and protein. By fluorophotometer (with mag-fura 2 fluorescent dye) and atomic absorption spectrophotometer, we confirmed that activation of CaSR by neomycin (0.5 mM) or gadolinium (1 mM) reinforced the decrease of [Mg(2+)](i) induced by Mg(2+) removal in the cells cultured in 10 mM Mg(2+)-containing medium. The neomycin-induced [Mg(2+)](i) decrease was inhibited by nicardipine (50 microM), but not by verapamil (50 microM) or amiloride (0.1 mM). These results indicate that CaSR monitors extracellular Mg(2+) concentration, and probably cause activation of Na(+)-independent Mg(2+)-transport system.

Amiloride↗
PubMed2001

Multidrug resistance-associated protein 3 is a tumor rejection antigen recognized by HLA-A2402-restricted cytotoxic T lymphocytes.

The identification of tumor rejection antigens recognized by CTLs and its application in peptide-based specific immunotherapy against melanomas have been extensively investigated in the past decade. However, only a small number of studies regarding these issues in other epithelial cancers have been reported. In this study, we show that a multidrug resistance-associated protein 3 (MRP3) is a tumor rejection antigen recognized by HLA-A2402-restricted CTLs established from T cells infiltrating into lung adenocarcinoma. MRP3 is expressed in differing quantities in tumor cells of various tissue types and origins. Four dominant MRP3-derived antigenic peptides that are recognized by the CTLs have been identified, each possessing in vitro immunogenicity. Namely, these four peptides (MRP3-503, MRP3-692, MRP3-765, and MRP3-1293) can induce peptide-specific CTLs after in vitro stimulation with these peptides in peripheral blood mononuclear cell cultures of HLA-A24(+) cancer patients, with the CTLs expressing cytotoxicity against HLA-A2402(+) MRP3(+) tumor cells but not against either HLA-A2402(-) or MRP3(-) target cells. The peptide specificity of the cytotoxicity of the CTLs was further confirmed by using peptide-loaded HLA-A24(+) EBV-transformed B cells. Widespread MRP3 expression in various tumor cell lines and tumor tissues at the mRNA level was confirmed. Furthermore, reactivities of the MRP3-peptide-induced CTLs against tumor cells correlated with MRP3 expression in the tumor cells. These results suggest that MRP3 and its derived peptides described in the present paper are potential candidates for cancer vaccines in regard to HLA-A24(+) patients with various tumors, particularly for those tumors that show anticancer drug resistance.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed2001

Efficiency of liposomes surface-modified with soybean-derived sterylglucoside as a liver targeting carrier in HepG2 cells.

We investigated the interaction of liposomes surface-modified with soybean-derived sterylglucoside (SG) (SG-liposomes) with HepG2 cells in the point of involvement of asialoglycoprotein receptor (ASGP-R) mediated endocytosis and examined the efficiency of SG-liposomes as drug carriers using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) as a maker of liposome, carboxylated polystyrene microspheres (Fluoresbrite) as a model drug not taken up in cells and doxorubicin (DXR). SG-liposomes were composed of dipalmitoylphosphatidylcholine (DPPC), cholesterol (Ch) and SG (DPPC/Ch/SG=6:3:1, molar ratio) and DiI, Fluoresbrite and DXR were entrapped in SG-liposomes, respectively. Each SG-liposome was incubated with HepG2 cells at 4 or 37 degrees C, and co-incubated with asialofetuin (AF) as a competitor of ASGP-R. The association of DiI, Fluoresbrite or DXR entrapped in SG-liposomes with HepG2 cells at 37 degrees C was significantly higher than that in liposomes containing no SG. That of DiI and Fluoresbrite was reduced significantly by the incubation with AF, but that of DXR was not affected. These findings suggest that Fluoresbrite behaves like the lipid component of SG-liposomes, but DXR in SG-liposomes does not behave similar to the lipid component of SG-liposomes, thus, its drug behavior released from liposomes may be due to its physicochemical properties. SG-liposomes are potentially useful drug carriers to the liver, because the glucose residue may work as a kind of ligand for ASGP-R.

Asialoglycoprotein Receptor↗
PubMed2001

Analysis of dominant-negative effects of mutant Env proteins of human immunodeficiency virus type 1.

The Env protein of human immunodeficiency virus type 1 is assembled into a stable trimer, and oligomerization is required for maintenance of viral infectivity. This property of Env suggests that Env mutants may have a dominant-negative effect on virus infectivity. To investigate this possibility, we established a packaging cell line in which both wild-type and mutant Env proteins could be expressed simultaneously in a single cell. We analyzed the effects of two types of Env mutants: cytoplasmic tail-truncated TM mutants and a mutant defective in gp120/gp41 cleavage. The cytoplasmic tail-truncated proteins were found to be incorporated into virions by forming an oligomer with wild-type TM, but could not inhibit the wild-type function. In contrast, phenotypic mixing of cleavage-defective Env with the wild-type protein caused dramatic inhibition of infectivity, indicating that this mutant has a strong dominant-negative phenotype.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Impaired FHIT expression characterizes serous ovarian carcinoma.

The FHIT (fragile histidine triad) gene on chromosome 3p14.2 is a candidate tumour suppressor gene. To define the role of the FHIT gene in the development of ovarian cancer, we have examined 33 ovarian carcinomas, 2 borderline tumours and 10 benign adenomas for the presence of FHIT gene alterations. FHIT transcripts were analysed by RT-PCR and sequencing. Aberrant FHIT transcripts were observed in 5/33 carcinomas (15%) and in 1 of 2 borderline tumours. Loss of normal FHIT transcript was observed in 5/33 carcinomas (15%) but not in 2 borderline tumours or 10 benign adenomas. Allelic losses at D3S1300 and D3S4103, both located within intron 5 of FHIT, were detected in 5/24 (21%) and 5/25 (20%) informative ovarian carcinomas, respectively. Expression of Fhit protein was analysed by immunohistochemistry in 44 carcinomas, 19 borderline tumours and 16 benign adenomas. Loss or significantly reduced expression of Fhit protein was observed in 6/44 (14%) ovarian carcinomas but not in any of 19 borderline tumours or 16 benign adenomas. The impaired Fhit protein expression was significantly correlated with the loss of normal FHIT transcription. Most notably, loss of normal FHIT transcript and impaired expression of Fhit protein occurred only in serous adenocarcinomas of grade 2 and 3 (5/15; 33% and 6/19; 32%, respectively). The present data suggest that inactivation of the FHIT gene by loss of expression is one of the important molecular events associated with the genesis of ovarian carcinoma, especially of high-grade serous carcinoma.

Acid Anhydride Hydrolases↗
PubMed2001

Structure and activity of the insect cytokine growth-blocking peptide. Essential regions for mitogenic and hemocyte-stimulating activities are separate.

Growth-blocking peptide (GBP) is a 25-amino acid insect cytokine found in Lepidopteran insects that possesses diverse biological activities such as larval growth regulation, cell proliferation, and stimulation of immune cells (plasmatocytes). The tertiary structure of GBP consists of a structured core that contains a disulfide bridge and a short antiparallel beta-sheet (Tyr(11)-Arg(13) and Cys(19)-Pro(21)) and flexible N and C termini (Glu(1)-Gly(6) and Phe(23)-Gln(25)). In this study, deletion and point mutation analogs of GBP were synthesized to investigate the relationship between the structure of GBP and its mitogenic and plasmatocyte spreading activity. The results indicated that deletion of the N-terminal residue, Glu(1), eliminated all plasmatocyte spreading activity but did not reduce mitogenic activity. In contrast, deletion of Phe(23) along with the remainder of the C terminus destroyed all mitogenic activity but only slightly reduced plasmatocyte spreading activity. Therefore, the minimal structure of GBP containing mitogenic activity is 2-23 GBP, whereas that with plasmatocyte spreading activity is 1-22 GBP. NMR analysis indicated that these N- and C-terminal deletion mutants retained a similar core structure to wild-type GBP. Replacement of Asp(16) with either a Glu, Leu, or Asn residue similarly did not alter the core structure of GBP. However, these mutants had no mitogenic activity, although they retained about 50% of their plasmatocyte spreading activity. We conclude that specific residues in the unstructured and structured domains of GBP differentially affect the biological activities of GBP, which suggests the possibility that multifunctional properties of this peptide may be mediated by different forms of a GBP receptor.

Amino Acid Sequence↗
PubMed2001

Cerebral hemorrhage due to heparin limits its neuroprotective effects: studies in a rabbit model of photothrombotic middle cerebral artery occlusion.

We investigated the efficacy of heparin on cerebral ischemic damage in a rabbit model of middle cerebral artery (MCA) photothrombosis and in the same model, cerebral hemorrhage induced by heparin as its side effect was also investigated. Using a photothrombosis model in rabbits, 38 animals were divided into four groups, heparin low-dose I and II, heparin high-dose and vehicle. In heparin low-dose I (n=10) or II (n=7), heparin was administered for 23.5 or 22 h, respectively, starting 30 or 120 min after the start of photo-irradiation to induce thrombosis. In high-dose (n=7), heparin was administered 30 min after the start of photo-irradiation for 23.5 h. In the vehicle treated group (control), 14 animals were infused continuously with saline for 23.5 h. Heparin at low and high doses prolonged Activated partial thromboplastin time (aPTT) by about 3 and 10 times compared with control group. The results show that cerebral hemorrhage was present in all animals, gross hemorrhage was observed in one animal each of the heparin low-dose I and high-dose groups, and in three animals of the heparin low-dose II group, while no gross hemorrhage was observed in control group. In heparin low-dose I, the size of cerebral infarction was significantly (P<0.01) reduced and neurological deficits were significantly (P<0.01) improved. In contrast, in heparin high-dose, the infarct size significantly increased, especially in the cortex (P<0.0001), and neurological deficits were significantly (P<0.01) worsened. In heparin low-dose II, the size of cerebral hemorrhage significantly (P<0.001) increased compared with the control group. In conclusion, using a photothrombotic model in the rabbit MCA, we have investigated the antithrombotic benefits and hemorrhagic risks associated with heparin. Of unique feature of our model is the fact that in a single animal model, we could evaluate doses of heparin which reduce cerebral infarction and doses which can promote cerebral hemorrhage. This model can be extended to determine both benefits and risks of antithrombotic agents.

Animals↗
PubMed2001

Differential regulation of Na(+),K(+)-ATPase and the Na(+)-coupled glucose transporter in hypertensive rat kidney.

Several Na(+) transporters are functionally abnormal in the hypertensive rat. Here, we examined the effects of a high-salt load on renal Na(+),K(+)-ATPase and the sodium-coupled glucose transporter (SGLT1) in Dahl salt-resistant (DR) and salt-sensitive (DS) rats. The protein levels of Na(+),K(+)-ATPase and SGLT1 in the DS rat were the same as those in the DR rat, and were not affected by the high-salt load. In the DS rat, a high-salt load decreased Na(+),K(+)-ATPase activity, and this decrease coincided with a decrease in the apparent Mechaelis constant (K(m)) for ATP, but not with a change of maximum velocity (V(max)). On the contrary, a high-salt load increased SGLT1 activity in the DS rat, which coincided with an increase in the V(max) for alpha-methyl glucopyranoside. The protein level of phosphorylated tyrosine residues in Na(+),K(+)-ATPase was decreased by the high-salt load in the DS rat. The amount of phosphorylated serine was not affected by the high-salt load in DR rats, and could not be detected in DS rats. On the other hand, the amount of phosphorylated serine residues in SGLT1 was increased by the high-salt load. However, the phosphorylated tyrosine was the same for all samples. Therefore, we concluded that the high-salt load changes the protein kinase levels in DS rats, and that the regulation of Na(+),K(+)-ATPase and SGLT1 activity occurs via protein phosphorylation.

Animals↗
PubMed2001

Integrin alpha3beta1 engagement disrupts intercellular adhesion.

During tissue morphogenesis and tumor invasion, epithelial cells must undergo intercellular rearrangement in which cells are repositioned with respect to one another and the surrounding mesenchymal extracellular matrix. Using three-dimensional aggregates of squamous epithelial cells, we show that such intercellular rearrangements can be triggered by activation of beta1 integrins after their ligation with extracellular matrices. On nonadherent substrates, multicellular aggregates (MCAs) formed rapidly via E-cadherin junctional complexes and over time became compacted spheroids exhibiting a more epithelial phenotype. After MCAs were replated on culture substrates, the spheroids collapsed to yield tightly arranged cell monolayers. Cell-cell contact induced rapid elevation in E-cadherin levels, which was due to an increase in the metabolic stability of junctional receptors. During MCA remodeling of cell-cell adhesions, and monolayer formation, their E-cadherin levels fell rapidly. Similar behavior was obtained regardless of which ECM ligand-collagen type I, fibronectin, or laminin 1-MCAs were seeded on. In contrast, when seeded onto a matrix elaborated by squamous epithelial cells, cells in the MCA attached, spread, lost cell-cell junctions, and dispersed. Analysis identified laminin 5 as the active ECM ligand in this matrix, and MCA dispersion required functional beta1 integrin and specifically alpha3beta1. Furthermore, substrate-immobilized anti-integrin antibody effectively reproduced the epithelial-mesenchymal-like transition induced by the laminin 5 matrix. During the early stages of aggregate rearrangement and collapse, cells on laminin 5 substrates, but not those on collagen I substrates, exhibited intense cortical arrays of F-actin, microspikes, and fascin accumulation at their peripheral surfaces. These results suggest that engagement of specific integrin-ligand pairs regulates cadherin junctional adhesions during events common to epithelial morphogenesis and tumor invasion.

Antibodies, Monoclonal↗
PubMed2001

Clinicopathologic study of mixed hepatocellular and cholangiocellular carcinoma: modes of spreading and choice of surgical treatment by reference to macroscopic type.

BACKGROUND AND OBJECTIVES: Clinicopathologic features and the choice of surgical treatment for mixed hepatocellular and cholangiocellular carcinoma (MHC) remain controversial. METHODS: We evaluated the clinicopathological features of seven cases of MHC (one autopsied and six surgically resected cases). MHCs were divided into two classes by reference to macroscopic appearance: four were of the single nodular (SN) type and three were of the multinodular (MN) type. RESULTS: The mean age of patients and mean preoperative level of serum alpha-fetoprotein were 44.5 years and 56,457 ng/ml for the SN type and 63.7 years and 1,227 ng/ml for the MN type, respectively. Histologically, invasion of the portal vein, the hepatic vein, and the perineural space was found in three, two, and zero cases of SN type tumors and in three, three, and one cases of MN type tumors, respectively. Lymph node metastases were found only in two patients with MN type MHC. CONCLUSIONS: MHC of the SN type had a pattern of infiltration similar to hepatocellular carcinoma. By contrast, MHC of the MN type resembled intrahepatic cholangiocellular carcinoma. It is suggested that lymphadenectomy might be necessary for treatment of selected MHC, in particular MHC with a multinodular appearance.

Adult↗
PubMed2001

Expression of steroidogenic factor-1 in frog embryo and developing gonad.

Steroidogenic factor-1 (SF-1), originally identified as an orphan nuclear receptor that regulates expression of genes encoding cytochrome P-450 steroid hydroxylases, is an essential transcriptional factor for adrenal and gonadal development in mammals. Since sex steroid hormones have been shown to play important roles in the sex determination of frogs, it is of interest to know how SF-1 gene expression is regulated during the sexual development of this organism. A previous study isolated the cDNA of the frog Rana rugosa SF-1 (rrSF-1) and found sexual differences in its gene expression in adult frogs; positive in testis and negative in ovary (Kawano et al., 1998). This study examined rrSF-1 gene expression in frog embryos and developing and mature gonads by immunohistochemical staining using anti-rrSF-1 protein antibody for protein localization and by in situ hybridization analysis for mRNA transcription. The results obtained in this study indicated that cells expressing SF-1 that originate in the mesoderm and endoderm probably migrate into the developing gonad via the dorsal mesentery, genital ridge, and mesorchium or mesovarium. Thus, SF-1 may play an important role in gonadal development in amphibians.

Adrenal Glands↗
PubMed2001

Different distribution of the activated areas in the dorsal premotor cortex during visual and auditory reaction-time tasks.

Sensorimotor association is an essential aspect of behavior. The dorsal part of the premotor cortex (PMd) is known to have an important role in sensorimotor association. Although it is suggested that the partially segregated groups of neurons are involved in sensorimotor association in different sensory modalities, it is not yet clear whether these groups occupy the PMd to the same or different extent. Therefore, we performed a functional magnetic resonance imaging study to compare activated regions in the PMd during simple reaction-time tasks with visual and auditory cues. Eight normal volunteers performed two simple reaction time tasks with a conventional on-off design; one is with a visual cue and the other is with an auditory cue. In both tasks, two regions in the left primary motor area (M1) (4a and 4p) and the bilateral PMd were activated. The two activated regions in the left M1 occupied the same areas in both the visual and the auditory tasks. However, in the PMd, the activated regions were situate medially during the visual task and laterally during the auditory task, along the precentral sulci. There was no overlap of significantly activated regions between two tasks, and areas specifically activated during the visual task were observed in the middle of the precentral sulci, bilaterally. The results suggest that the distribution of PMd subregions involved in sensorimotor association differ when the sensory cues are in different modalities.

Adult↗
PubMed2001

Initiation of smooth pursuit in humans. Dependence on target saliency.

We examined the influence of target saliency on the initiation of smooth pursuit. The eye movements of five human subjects were recorded with the scleral search-coil technique. A video-projection system was used to create a pursuit target, consisting of a cluster of 14 red or green dots (0.5 degrees squares) extending randomly over a 3 degrees x3 degrees region, and a surrounding background, consisting of stationary, random dots of the same size and density extending over an area 70 degrees x 40 degrees. When the dots in the background and the target were of the same color, the target was indistinguishable from the background until it started to move. On the other hand, when the colors were different, the target was salient, even when stationary. We measured the changes in eye position over the 70-ms interval starting 70 ms after the onset of target motion (initial tracking response). When the target moved toward the fovea (centripetal motion), the initial tracking responses developed earlier when the dots in the target and background were of different color than when the two sets of dots were of the same color. However, in order to see this effect of target salience, it was critical that the colors be different before the onset of motion, but not afterwards. When the target moved away from the fovea (centrifugal motion), the initial tracking responses were independent of whether the colors of the target and the background were the same or different. Our data indicate that the initiation of tracking responses is very sensitive to the saliency of the target before the onset of target motion when that motion is toward the fovea.

Adult↗
PubMed2001

Fourier-transform infrared spectroscopic study of Ca2+-binding to osteocalcin.

Osteocalcin, the gamma-carboxyglutamic acid-containing protein, which is the most abundant noncollagenous protein of bone and dentin, is considered to play roles in bone formation and remodeling. It is unclear how the gamma-carboxyglutamic acid side-chains in osteocalcin coordinate to Ca2+, since the X-ray structure of osteocalcin is not available. Interactions between Ca2+ and the gamma-carboxyglutamic acid side-chains in osteocalcin were investigated by Fourier-transform infrared spectroscopy. In the region of the antisymmetric stretches, the loss of intensity at 1574 cm(-1) and gain of intensity at 1600 cm(-1) were observed due to Ca2+-binding to osteocalcin. The spectral changes indicate that the gamma-carboxyglutamic acid side-chains in osteocalcin coordinate to Ca- in the malonate chelation mode, where a Ca2+ interacts with two oxygen atoms, one from each of the two COO- groups of a single gamma-carboxyglutamic acid residue. Addition of Ca2+ does not cause any spectral change in the spectra of decarboxylated osteocalcin since the gamma-carboxyglutamic acid residues are converted to the glutamic acid residues by chemical modification.

Animals↗
PubMed2001

Demonstration of the postcommissural fibres of the fornix in short-inversion time inversion-recovery imaging on a high-field system.

Short-inversion time inversion-recovery (STIR) imaging using a 3 tesla system was assessed to reveal the postcommissural fibres (PF) of the fornix, which have rarely been highlighted neuroradiologically in the clinical setting. We studied 27 normal subjects. Sequence parameters were TR/TE/TI 8000/52/ 150 ms. STIR was expected to take advantage of the high signal-to-noise ratio of a high-field system, due to the long repetition time. PF were identifiable in axial and coronal slices in all cases. They were bordered anteriorly and superiorly by the anterior commissure and posteriorly and inferiorly by the mamillary body. Behind the anterior commissure, they ran in an arch-shaped posterior and inferior course in the hypothalamic nuclei and joined the mamillary body anterolaterally. They usually extended through three 3-mm slices (with 1 mm interslice gap) in anteroposterior and vertical dimensions. Little variation was observed in their course or size. Demonstration of the PF would provide a more detailed correlation of human neuroanatomy to hypothalamic function and individualised understanding of hypothalamic pathology and influence therapy.

Adolescent↗
PubMed2001

Expansion of an ablated site and induction of apoptosis after microwave coagulation therapy in rat liver.

BACKGROUND/PURPOSE: Microwave coagulation therapy (MCT), one of the ablation therapies, has been widely used to treat liver cancers, yielding excellent clinical results. Despite its efficacy, the precise events that take place in the ablated liver after MCT remain unknown. We investigated sequential histologic changes around MCT sites and the relationship between MCT and apoptosis in rat liver. METHODS: One session of MCT at 30 W was applied to rat liver. The rats were killed at 0, 2, 6, 12, 24, 72, and 168 h after MCT. The liver surface area was measured for sequential evaluations of the size of the impaired field (i.e., the liver surface affected by MCT). The size of the impaired field was assessed by measuring the area that showed macroscopic changes in color with a relatively clear border. To assess apoptosis, we examined terminal deoxynucleotidyl transferase d-uridine triphosphate nick end labeling stained sections, determined the positive cell count for DNA fragmentation, and observed DNA ladder formation by gel electrophoresis. Caspase-3 activity at the ablated margin was measured for the enzymatic evaluation of apoptosis. RESULTS: The impaired field gradually expanded through 12 h after MCT. Caspase-3 activity increased four fold from the baseline, peaking at 2 h after MCT, and DNA fragmentation, confirmed by DNA ladder formation, was significantly increased at 6 h. CONCLUSIONS: Alterations in the ablated liver tissue indicated that the activation of caspase-3 around the MCT site was followed by apoptosis and expansion of the impaired field. The expansion continued until 12 h after MCT, and this may be beneficial for the local control of liver cancer.

Animals↗