Biomedical subjects

K Ishikawa

Publications and source records attributed to K Ishikawa.

At least 73 records · Page 4Linked to original sources

PubMed2001

Spleen-preserving laparoscopic distal pancreatectomy with conservation of the splenic artery and vein for a large insulinoma.

We report a successful spleen-preserving laparoscopic distal pancreatectomy for a large insulinoma with conservation of the splenic artery and vein. The patient was a 48-year-old man with syncope due to hypoglycemia. Abdominal computed tomography (CT) and ultrasonography revealed a large 6-cm mass located in the tail of the pancreas. We adopted the laparoscopic approach to remove the tumor. After careful dissection and an accurate hemostasis between the pancreas and splenic vessels, laparoscopic distal pancreatectomy was carried out using a linear stapler. There were no perioperative complications. The patient was discharged uneventfully. He had no hypoglycemic episodes or abdominal symptoms during 8 months of follow-up. When performed by experienced laparoscopic surgeons in conjunction with intraoperative ultrasonography, spleen-preserving laparoscopic distal pancreatectomy with conservation of the splenic artery and vein is a technically feasible procedure for the treatment of benign lesions of the tail or body of the pancreas.

Humans↗

PubMed2001

Immunolocalization of hepatocyte growth factor and its receptor (c-Met) during mouse liver development.

Although hepatocyte growth factor (HGF) was discovered as a potent hepatotrophic factor responsible for liver regeneration and may involve some organ development in embryogenesis, it remains to be revealed what roles HGF plays in liver development. The present study was undertaken to determine which cells express HGF and its receptor c-Met and when c-Met is activated in mouse liver development by using immunoblotting and immunohistochemical techniques. HGF was detected in hepatocytes and non-parenchymal cells, including biliary epithelial cells, periportal connective tissue cells, megakaryocytes, endothelial cells, and sinusoidal cells, throughout liver development. Positive HGF immunostaining in hepatocytes increased during postnatal development, and reached the maximal level in the adult stage. c-Met protein was also expressed in hepatocytes throughout liver development, but maximal staining was obtained in 1- or 2-week-old livers. Phosphorylation of tyrosine residues in the c-Met beta chain also occurred in these stages. These results suggest that HGF signaling is implicated in hepatocyte growth during postnatal liver development, and its action could be in a paracrine mode; HGF produced by non-parenchymal cells such as sinusoidal cells acts on hepatocytes expressing c-Met receptors. Positive immunostaining in adult and postnatal hepatocytes may be derived from their blood clearance of HGF.

Animals↗

PubMed2001

Patterns in hybrid nematic liquid-crystal films: topography and topology.

Spontaneous pattern formation in hybrid nematic liquid-crystal films on glycerol was studied with both polarized transmission and unpolarized monochromatic reflected light microscopy. These observations reveal that the patterns that are found in 1 to 10-microm-thick films are due to a combination of film topography, gradients in film thickness that act as an aligning field, and topology, connectivity requirements on the vector field. The patterns studied include cellular patterns, disclinations connected by 2pi-walls, and 2pi-walls that narrow to a point at the edge of the films.

Journal Article↗

PubMed2001

Heme oxygenase-1 inhibits atherogenesis in Watanabe heritable hyperlipidemic rabbits.

BACKGROUND: Heme oxygenase-1 (HO-1) is proposed to have a variety of adaptive responses against oxidative stress. To examine the function of HO-1 against atherogenesis in vivo, we observed the effects of HO-1 inhibition on atherosclerotic lesion formation in Watanabe heritable hyperlipidemic rabbits (WHHL). Methods and Results- During 4 weeks of a 1% cholesterol diet, intravenous injections of Sn-protoporphyrin IX to inhibit HO-1 (S group, n=10) and saline as a control (C group, n=10) were given to 3-month-old WHHL rabbits. The percentages of en face atherosclerotic lesion areas in total descending aorta by Sudan IV staining (EFA) and the ratio of intima to media in microscopic atherosclerotic lesions in the ascending aortas (I/M) were calculated. Two different quantitative methods revealed significantly greater atherosclerotic lesions in the S group than the C group (EFA, P<0.001; I/M, P<0.005). HO-1 expression in atherosclerotic lesions was confirmed by Northern blot and immunohistochemical analyses. The dominant cell types expressing HO-1 were macrophages and foam cells, in which oxidized phospholipids were also accumulated. HO inhibition increased plasma and tissue lipid peroxide levels without affecting plasma lipid co osition. CONCLUSIONS: These results suggest the possibilities that HO-1 has antiatherogenic properties in vivo and that the antiatherogenic properties of HO-1 are conducted through the prevention of lipid peroxidation.

Animals↗

PubMed2001

Human hypertension caused by mutations in WNK kinases.

Hypertension is a major public health problem of largely unknown cause. Here, we identify two genes causing pseudohypoaldosteronism type II, a Mendelian trait featuring hypertension, increased renal salt reabsorption, and impaired K+ and H+ excretion. Both genes encode members of the WNK family of serine-threonine kinases. Disease-causing mutations in WNK1 are large intronic deletions that increase WNK1 expression. The mutations in WNK4 are missense, which cluster in a short, highly conserved segment of the encoded protein. Both proteins localize to the distal nephron, a kidney segment involved in salt, K+, and pH homeostasis. WNK1 is cytoplasmic, whereas WNK4 localizes to tight junctions. The WNK kinases and their associated signaling pathway(s) may offer new targets for the development of antihypertensive drugs.

Amino Acid Sequence↗

PubMed2001

Holes and disclinations in hybrid nematic liquid crystal films.

Defect patterns in hybrid nematic liquid crystal films of pentylcyanobiphenyl (5CB) on a glycerol surface were studied with polarized transmission and monochromatic reflected light microscopy. We report that disclinations of apparent topological strength zero, stable pairs of +1 and -1 disclinations, and higher strength defects found in these films are stabilized by holes in the liquid crystal film. These holes are produced by a monolayer of surfactant on the glycerol surface. In addition, we describe the topology of the director field in the film during the coalescing of two such holes.

Journal Article↗

PubMed2001

Expression, purification, crystallization and preliminary X-ray diffraction analysis of the human calcium-binding protein MRP14 (S100A9).

MRP14 is a protein that is specifically expressed in myeloid and epithelial cells during the stages of acute or chronic inflammatory states such as rheumatoid arthritis or sarcoidosis. MRP14 has EF-hand motifs as Ca(2+)-binding sites and belongs to the S100 family of proteins. This paper deals with the sample preparation (cloning, overexpression and purification), crystallization and preliminary crystallographic analysis of recombinant human MRP14. Crystals of MRP14 were obtained by the hanging-drop vapour-diffusion method. MRP14 crystals belong to space group P2(1), with unit-cell parameters a = 57.59, b = 178.44, c = 61.23 A, beta = 113.17 degrees, and diffract to 2.1 A resolution.

Amino Acid Sequence↗

PubMed2001

Infectious DNA clone of HIV type 1 A/G recombinant (CRF02_AG) replicable in peripheral blood mononuclear cells.

We constructed an infectious DNA clone of the HIV-1 A/G recombinant 97GH-AG2, which was isolated in Ghana in 1997 and was classified originally as subtype A. By phylogenetic and recombination breakpoint analyses, p97GH-AG2 was grouped in the circulating form of A/G recombinants (CRF02_AG) and was found to contain the least amount of subtype G-derived region among the known CRF02_AG HIV-1 DNAs. This result suggests that CRF02_AG may be a predominant form in Ghana. Virions produced by transfection of p97GH-AG2 into 293T cells grew in phytohemagglutinin-stimulated peripheral blood mononuclear cells (PBMCs). 97GH-AG2 also replicated efficiently in CCR5-expressing HeLa cells, MAGIC5, but only weakly in the parent MAGI cells, indicating that 97GH-AG2 uses mostly CCR5 as a coreceptor. Isolation of the first HIV-1 (CRF02_AG) DNA clone that replicates in PBMCs will accelerate the molecular analysis of this subtype.

Adult↗

PubMed2001

Cytoplasmic and nuclear polyglutamine aggregates in SCA6 Purkinje cells.

Aggregations of the alpha1A-calcium channel protein have been previously demonstrated in spinocerebellar ataxia type 6 (SCA6). Here the authors show that small aggregates, labeled by a monoclonal antibody 1C2 that preferentially detects expanded polyglutamine larger than that in SCA6 mutation, are present mainly in the cytoplasm but also in the nucleus of Purkinje cells. Although the length of expansion is small in SCA6, the current finding might indicate that SCA6 conforms to the pathogenic mechanism(s) in other polyglutamine diseases.

Brain↗

PubMed2001

Initial tissue response to anti-washout apatite cement in the rat palatal region: comparison with conventional apatite cement.

Initial tissue response to anti-washout apatite cement (aw-AC) in the palatal region was studied. Conventional apatite cement (c-AC) was employed as a control material. Bone defects generated in the rat palatal region, where complete hemostasis is difficult to effect, were filled with both cement types and examined histologically for up to 8 weeks. At 1-week postfilling, a portion of the c-AC had washed out, resulting in slight inflammation and severe foreign-body response. The degree of foreign-body response to c-AC was reduced over time; however, foreign-body response continued to be in evidence 8 weeks after surgery. As a result, poor bone formation was observed in the case of c-AC at 8 weeks post-surgery. In contrast, aw-AC set well, maintained its shape at implantation, and caused little foreign-body response. Osteoblasts were observed at 2 weeks following surgery. Moreover, the bone defect was completely covered with new bone at 8 weeks post-surgery. This observation suggests that aw-AC may be used without complication in cases where complete hemostasis is difficult to achieve, that is, where the use of c-AC is contraindicated.

Animals↗

PubMed2001

Relation of ST-segment changes in inferior leads during anterior wall acute myocardial infarction to length and occlusion site of the left anterior descending coronary artery.

We investigated the relation between left anterior descending (LAD) coronary artery morphology and inferior lead ST-segment changes to elucidate the clinical significance of such changes in 159 patients with anterior wall acute myocardial infarction (AMI). Patients with 1-vessel LAD artery lesions were divided into an ST depression group (n = 40), an ST elevation group (n = 25), and a no-ST-change group (n = 94) based on ST-segment changes in the inferior leads. The relation between each group and the infarct-related lesion and the presence of a wrapped LAD artery was then investigated. The percentage of patients with the infarct-related lesion in the proximal LAD artery was significantly higher in the ST depression group and significantly lower in the ST elevation group. The percentage of patients with a wrapped LAD artery was significantly higher in the ST elevation group and significantly lower in the ST depression group. The wall motion index determined echocardiographically was significantly higher in the ST depression group and the no-ST-change group than in the ST elevation group. Our findings suggest that inferior lead ST-segment changes during anterior wall AMI arise as a result of competition between reciprocal changes caused by high lateral wall AMI due to lesions of the proximal LAD artery, which depress the ST segment, and inferoapical wall AMI due to a wrapped LAD artery, which elevates the ST segment. In patients with no ST-segment changes, echocardiography was useful for distinguishing the amount of affected LAD artery territory.

Adult↗

PubMed2001

Taxon-specific zeta -crystallin in Japanese tree frog (Hyla japonica) lens.

The present study demonstrated that the 38-kDa protein, instead of rho-crystallin (36 kDa), is expressed taxon specifically in the lens of Japanese tree frog (Hyla japonica). The 38-kDa protein was distinguished from rho-crystallin expressed in the lenses of bullfrog (Rana catesbeiana) and European common frog (Rana temporaria) immunochemically. Although the N terminus of the 38-kDa protein was blocked, the analyses of partial amino acid sequences showed that the protein was zeta-crystallin. Analysis of cDNA sequence encoding zeta-crystallin of the tree frog lens demonstrated that the deduced protein consisted of 329 amino acids including initial methionine and having 62.2 and 62.9% identity with zeta-crystallin of camel and guinea pig lenses, respectively. The molecular mass of the deduced structure was calculated to be 35,564 Da. zeta-Crystallin of the tree frog lens exhibited the intrinsic enzymatic activity of quinone reductase (EC, NADPH:quinone oxidoreductase). The crystallin specifically catalyzed the reduction of 9,10-phenanthrenequinone (Km, 42 microm) using NADPH (Km, 60 microm) as a cofactor. The enzymatic activity was inhibited by dicumarol, anti-coagulant drug, with IC50 of 4 microm. On gel filtration chromatography, the crystallin was recovered as 150-kDa molecular mass complex, indicating that the crystallin was homotetramer consisting of 38-kDa subunits. The crystallin gene was expressed specifically in the lens. These results show that taxon-specific crystallins such as zeta- and rho-crystallins may be available for the biochemical discrimination of Hyla- and Rana groups among frogs.

Amino Acid Sequence↗

PubMed2001

Molecular orientation near the surface of a smectic liquid crystal cell showing V-shaped switching by means of attenuated total internal reflection ellipsometry.

Attenuated total internal reflection ellipsometry was used to probe the molecular orientation and switching near the surface of a smectic liquid crystal cell showing V-shaped switching. We find that the switching occurs collectively near the surface as in the bulk. The molecules form a twisted state, but the twist angle relative to the bulk layer normal is small because of compensating twist of the smectic layer normal. As a result, a rather uniform molecular orientation is produced, resulting in high extinction and a high contrast ratio in the absence of a field.

Journal Article↗

PubMed2001

Observation of a pretransitional effect near a virtual smectic-A--smectic-C* transition.

Unusual softening of the layer compression modulus B has been observed near the phase boundary where the smectic-C* phase vanishes in a naphtalene-based liquid crystal mixture. From the systematic study of x-ray and layer compression measurements, this unusual effect is attributed to the pretransitional softening near a virtual smectic-A-smectic-C* phase transition in the smectic-A phase, which no longer appears on the thermoequilibrium phase diagram. This phenomenon is similar but not equivalent to supercritical behavior.

Journal Article↗

PubMed2001

Inflammatory stimuli increase prostaglandin D synthase levels in cerebrospinal fluid of rats.

To examine the possibility that prostaglandin D synthase in CSF is involved in the brain responses to inflammation, we monitored the enzyme levels before and after administration of a bacterial endotoxin lipopolysaccharide (LPS) or proinflammatory cytokines. After an i.p. injection of LPS, the synthase levels began to rise within 1 day, peaked at 2 days and returned to the basal by 5 days after injection. The enzyme levels increased in a similar manner in response to tumor necrosis factor-alpha or interleukin (IL)-1 beta injected i.v. Centrally administered IL-1 beta had a similar effect. These findings support the hypothesis that PGD synthase in CSF participates in the brain responses to inflammation.

Animals↗

PubMed2001

Isolation and characterization of a full-length molecular DNA clone of Ghanaian HIV type 1 intersubtype A/G recombinant CRF02_AG, which is replication competent in a restricted host range.

We have isolated a replication-competent, full-length molecular clone of HIV-1 CRF02_AG, designated p97GH-AG1, by reconstituting two separately amplified genomic regions of an HIV-1 provirus of a 1997 Ghanaian isolate. The phylogenetic and recombination breakpoint analyses revealed that 97GH-AG1 had an A/G recombinant structure similar to that of prototype Nigerian isolate IbNG. The 17-nucleotide insertion downstream of the primer-binding site appeared to be a common sequence signature specific to most CRF02_AG strains, including 97GH-AG1. 97GH-AG1 showed an R5 phenotype and exerted productive infection in both HOS and NP2 cell infectivity assays, whereas it failed to show a detectable level of progeny production in peripheral blood mononuclear cells (PBMCs). The data may suggest the presence of unknown determinant(s) that dictate efficient replication in PBMCs, but that are not required for replication in immortalized cell lines.

Amino Acid Sequence↗

PubMed2001

Observation of a soft smectic liquid-crystal phase in a mixture showing V-shaped switching.

We present the experimental observation of a soft smectic liquid crystal phase in a three-component liquid crystal mixture reported to exhibit V-shaped switching. Unlike the layer compression modulus B of the usual smectic phase, B of the soft smectic phase has a peculiar temperature and frequency dependence. It was found that this characteristic feature is one of the main driving force to realize an ideal V-shaped switching.

Journal Article↗

PubMed2001

Special phase matching of second-harmonic generation in helical ferroelectric liquid crystal cells.

The helical structures in ferroelectric liquid crystals can be utilized to realize a special phase matching for second-harmonic generation (SHG) when two counter fundamental waves propagate along the helical axis and the wavelength of SHG is near the photonic (selective reflection) band edge. On the basis of the exact theory [Drevensek-Olenik and Copic, Phys. Rev. E 56, 581 (1997)], a simple analytical description is derived and some characteristic features of the special phase matching are shown. (1) Special phase matching is definitely achieved under particular combinations of polarization. (2) The SH spectrum is related to a subsidiary oscillating structure in the selective reflection spectrum. The maximum SH intensity is realized at the first dip of the oscillation near one of the edges in the selective reflection band. (3) The thickness (d) dependence of the maximum SH intensity is d4 in thick cells, while it is d2 for conventional phase matching. (4) The linewidth for the SH peak is d(-3) dependent, which is much narrower than in conventional phase matching.

Journal Article↗