Biomedical subjects

K Ishihara

Publications and source records attributed to K Ishihara.

At least 343 records · Page 19Linked to original sources

PubMed1995

Molecular cloning of a cDNA that encodes the precursor to several exogastrula-inducing peptides, epidermal-growth-factor-related polypeptides of the sea urchin Anthocidaris crassispina.

Complementary DNA clones for exogastrula-inducing peptides (EGIPs) of the sea urchin Anthocidaris crassispina, which are related to epidermal growth factor (EGF), were obtained from a cDNA library of late gastrula embryos using, as probe, the partial cDNA for one of the EGIP (EGIP-D) obtained by the reverse-transcription PCR method. The longest cDNA was composed of 1662 bp, and encoded a protein of approximately 36 kDa with a region that resembled a signal sequence. The deduced protein contains the sequences of EGIP-C, EGIP-D, and EGIP-A in that order, followed by the sequence for an unidentified EGIP-like polypeptide. When expressed in Escherichia coli as a fusion protein with beta-galactosidase, the product for the cDNA was specifically recognized by a rabbit antibody raised against EGIP-D that had been purified from embryos. Characteristic amino acid residues were found around the N-terminus and the C-terminus of each EGIP sequence, suggesting a specific processing mechanism for the generation of the individual EGIPs from the precursor. RNA-blot analysis revealed the presence of EGIP mRNA in unfertilized eggs. The level of this mRNA decreased gradually after fertilization, began to increase dramatically after the onset of gastrulation, and continued to increase through the pluteus stage. Genomic Southern-blot analysis suggested that this gene is present as a single copy. A homology search showed that the EGIP cDNA has a similarity to the cDNA for SpEGF2 which was cloned as a gastrula-specific gene in another sea urchin, Strongylocentrotus purpuratus.

Amino Acid Sequence↗

PubMed1995

Digital subtraction high-frame-rate echocardiography in detecting delayed onset of regional left ventricular relaxation in ischemic heart disease.

BACKGROUND: Because left ventricular (LV) diastolic function is impaired before systolic function in patients with ischemic heart disease and because ischemic heart disease is constituted of regional rather than global abnormalities of the left ventricle, measures of LV regional diastolic dysfunction, if possible, should provide the most sensitive assessment of the coronary involved region. The objectives of this study are to clarify whether high-frame-rate two-dimensional echocardiography, combined with digital subtraction image processing, may be used to visualize regional LV relaxation abnormalities in patients with ischemic heart disease and to clarify whether this technique provides a measure for the noninvasive assessment of the coronary involved region. METHOD AND RESULTS: In 30 normal subjects and 59 patients with ischemic heart disease, two-dimensional echocardiograms obtained at a rate of 60 frames per second were provided on line for digital subtraction analysis, with which digitized images were continuously subtracted on a frame-by-frame basis. The subtracted images were analyzed to determine the onset of the segmental outward motion of the LV wall in early diastole in each of 16 segments per subject. Regional relaxation index, defined as the interval from the second heart sound to the onset of outward wall motion, was significantly prolonged in the coronary involved segments compared with the normal segments (36.3 +/- 18.0 versus 101.2 +/- 34.0 ms, P < .01). The prolongation in the regional relaxation index was observed even in the coronary involved segments without reduction in systolic wall motion. When a cutoff level of 50.0 ms was used, coronary involved segments could be distinguished from normal or border segments with a sensitivity of 92% and a specificity of 81%. CONCLUSIONS: Digital subtraction high-frame-rate echocardiography may be used to visualize regional LV relaxation abnormalities in patients with ischemic heart disease. The time interval from the second heart sound to the onset of the segmental outward motion of the LV wall (regional relaxation index) obtained with this technique provides a noninvasive and accurate measure for assessing coronary involved regions.

Adult↗

PubMed1995

Improvement of blood compatibility on cellulose dialysis membrane. III. Synthesis and performance of water-soluble cellulose grafted with phospholipid polymer as coating material on cellulose dialysis membrane.

To improve the surface blood compatibility on a cellulose hemodialysis membrane, a blood compatible polymer with a phospholipid polar group, poly[2-methacryloyloxyethyl phosphorylcholine(MPC)], was immobilized on the surface through the coating of a water-soluble cellulose grafted with poly(MPC) (MPC-grafted cellulose, MGC). The MGC was synthesized by graft copolymerization of MPC on a water-soluble cellulose using cerium ion as an initiator. The coating process on the cellulose membrane with an aqueous solution of the MGC was convenient, and the MGC on the surface was not significantly detached even after immersion in water. The permeability and mechanical strength of the membrane coated with the MGC did not decrease compared with the original membranes. The MGC-coated cellulose membrane was blood compatible, as determined by the prevention of platelet adhesion and aggregation after contact with platelet-rich plasma. From these results, it is concluded that the MGC may be a useful material for improving the blood compatibility of the cellulose hemodialysis membrane.

Animals↗

PubMed1995

Adsorption-desorption of proteins on phospholipid polymer surfaces evaluated by dynamic contact angle measurement.

Adsorption-desorption of plasma protein on various polymer membranes was evaluated by a dynamic contact angle (DCA) measurement using the Wilhelmy plate method. Poly(ethylene terephthalate) (PET) was used as a substrate membrane; we examined this membrane coated with hydrophilic polymers such as poly[2-methacryloyloxethyl phosphorylcholine (MPC)-co-n-butyl methacrylate (BMA)] or poly[2-hydroxyethyl methacrylate (HEMA)]. Although the zeta-potential of the PET membrane was negative, the coating with poly(MPC-co-BMA) induced increase of value to nearly zero. The DCA loops observed on the polymer membranes after protein adsorption were unity and hysteresis of the loop was reduced. In the cases of protein adsorbed on both the PET and the poly(HEMA) membranes, the shape and hysteresis of the loops were almost same during the rinsing process with a phosphate-buffered solution (PBS). However, the hysteresis of the DCA loops that appeared on the protein-adsorbed poly(MPC-co-BMA) membrane became large during the rinsing process with the PBS, and the shape of the DCA loop returned to its non-protein-adsorbed state. Therefore, proteins adsorbed on poly(MPC-co-BMA) could desorb more readily than those on PET and poly(HEMA) because of the weak interaction between poly(MPC-co-BMA) and the proteins.

Adsorption↗

PubMed1995

Adhesion and cytokine production by monocytes on poly(2-methacryloyloxyethyl phosphorylcholine-co-alkyl methacrylate)-coated polymers.

Human monocytes isolated from peripheral venous blood were assayed for their ability to adhere to various polymers. The culture supernatants were also assayed for the cytokines, interleukin-1 beta (IL-beta), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-alpha). The polymers evaluated for adherence and cytokine production included Pellethane, polyethylene and poly[n-butyl methacrylate (BMA)] coated with poly[2-methacryloyloxyethyl phosphorylcholine (MPC)-co-alkyl methacrylate] copolymers. In some experiments the test polymers were adsorbed with fibrinogen or IgG prior to the addition of monocytes. MPC copolymer-coated materials inhibited monocyte and macrophage adhesion after 1 and 8 days of culture relative to corresponding uncoated polymers and tissue culture polystyrene (TCPS). The degree of inhibition by coated Pellethane compared to uncoated Pellethane was the greatest, while inhibition of adhesion by coated poly(BMA) was the least compared to uncoated poly(BMA). However, adhesion was significantly decreased on both coated and uncoated poly(BMA) by day 8. While IL-1 beta, IL-6, and TNF-alpha release was variably influenced by polymer coating, release was consistently inhibited relative to TCPS on day 1. However, cytokine production was not inhibited compared to corresponding uncoated polymers on day 1. With or without protein preadsorption, IL-1 beta release was not detectable in the supernatants of any polymer on day 8, IL-6 production was diminished on day 8, and TNF-alpha production was sustained on day 8. Overall, MPC copolymer-coated and uncoated poly(BMA) were the least stimulating, while TCPS was the most stimulating.(ABSTRACT TRUNCATED AT 250 WORDS)

Biocompatible Materials↗

PubMed1995

Autologous reconstruction of pulmonary trunk at reoperation after extracardiac conduit repair.

Between 1991 and 1993, 5 patients underwent reoperation for critical stenosis of extracardiac conduit. Indication for extracardiac conduit repair was pulmonary truncal atresia in 3 patients and coronary anomaly including single left coronary artery and left anterior descending artery from right coronary artery in 2 patients. Age at reoperation ranged from 8 to 23 years (mean, 16.2 years). Preoperative systolic pressure ratio of right to left ventricles ranged from 0.83 to 1.05 (mean, 0.93), with the pressure gradient across the conduit ranging from 52 to 100 mm Hg (mean, 74.4 mm Hg). At reoperation, stenotic conduit was completely removed and central pulmonary artery was extensively mobilized. In 4 patients who had a relatively short distance (15 to 25 mm) between the pulmonary arterial stump and the right ventriculotomy incision, the distal pulmonary arterial stump was anastomosed directly to the cranial margin of the right ventriculotomy incision to serve as a floor mode of autologous tissue. In 1 patient with a long distance (40 mm), right ventricular-pulmonary arterial continuity was restored with a tailored autologous pericardial tube. There were no early or late deaths. Postoperative catheterization study revealed a satisfactory reduction of right ventricular pressure with the systolic pressure ratio ranging from 0.42 to 0.51 (mean, 0.47) and the pressure gradient across the right ventricular outflow tract ranged within 13 mm Hg (mean, 5 mm Hg). Restoration of right ventricular-pulmonary arterial continuity was successfully achieved by introducing the concept of autologous tissue repair even at reoperation instead of the insertion of new extracardiac conduit in patients with tetralogy of Fallot after extracardiac conduit repair.

Adolescent↗

PubMed1995

Surgical management of tricuspid malinsertion in the Rastelli operation: conal flap method.

From June 1986 to May 1994, 25 patients underwent the Rastelli operation for complete transposition of the great arteries with ventricular septal defect and pulmonary stenosis or atresia. Fourteen patients whose tricuspid valve chordae were normal underwent the conventional Rastelli procedure (conventional group), whereas 11 patients who had tricuspid malinsertion into the infundibular septum underwent the Rastelli operation concomitant with mobilization of the infundibular septal flap, with the tricuspid valve chordae, to the right ventricular side of the intraventricular conduit (conal flap method) (conal flap group). In relation to the mobilization of the tricuspid valve chordae, right heart function and tricuspid regurgitation were compared between the two groups. There was one early death after the conventional Rastelli procedure and no early death after the Rastelli operation with a conal flap. There was one late death in the conventional group and two late deaths in the conal flap group. The mean follow-up was 50.8 +/- 5.1 months in the conventional group and 54.9 +/- 7.5 months in the conal flap group (p = 0.43). Reoperation was necessary for 1 patient in the conal flap group during follow-up. At the most recent follow-up, all patients in both groups were in New York Heart Association functional class I. Tricuspid regurgitation was estimated from the echocardiograms. Mild to moderate regurgitation was noted in 6 patients in the conventional group and 8 in the conal flap group. However, postoperative right heart catheterization data did not show any significant differences.(ABSTRACT TRUNCATED AT 250 WORDS)

Abnormalities, Multiple↗

PubMed1995

Fabrication and characterization of dipalmitoylphosphatidylcholine-attracting elastomeric material for joint replacements.

Wear debris associated with the polyethylene components of total joint replacements has been shown to induce bone resorption which contributes to implant loosening. In an effort to promote lubrication and reduce wear in artificial hip joints, the use of the cushion bearing concept has been proposed previously; however, an elastomeric material tested as a cushion bearing has been shown to have poor tribological properties during initiation of motion from rest. The goal of this project was to fabricate and characterize an elastomer that has the ability to attract to its surface naturally occurring boundary lubricants from an aqueous solution. The test elastomer and appropriate controls were characterized using fluorescence, electron spin resonance and X-ray photoelectron spectroscopy. The test elastomer was found to have an enhanced ability to attract dipalmitoylphosphatidylcholine, a known physiological boundary lubricant. A cushion bearing that also encourages boundary lubrication represents a potential improvement over currently existing orthopaedic implant-bearing materials.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed1995

Synthesis of phospholipid polymers having a urethane bond in the side chain as coating material on segmented polyurethane and their platelet adhesion-resistant properties.

Surface modification of segmented polyurethanes (SPUs) was carried out using new blood compatible polymers having both phospholipid polar groups and urethane bonds in the side chains. The polymers were composed of 2-methacryloyloxyethyl phosphorylcholine (MPC), n-butyl methacrylate (BMA) and methacrylate with a urethane bond (MU). The MPC copolymers were soluble in ethanol. The SPU membranes were immersed in an ethanol solution of MPC copolymers and dried in vacuo for coating. The surface formed was completely covered with the MPC copolymer which was confirmed by X-ray photoelectron spectroscopic analysis. The polymer coatings were hardly detached in water, ethanol and 40% aqueous solution of ethanol compared with poly(MPC-co-BMA) which did not have the MU moieties. Therefore, the MU moieties had affinity for the SPU. The surface modification of the SPUs suppressed platelet adhesion effectively after contact with platelet-rich plasma for 180 min.

Biocompatible Materials↗

PubMed1995

Mechanism of enhancement of the immune responses to influenza vaccine with cholera toxin B subunit and a trace amount of holotoxin.

Cholera toxin B subunit (CTB) (1 microgram) and a trace amount of cholera toxin (CT) (0.1-10 ng), when inoculated intranasally into Balb/c mice together with influenza vaccine, induced synergistically a greater delayed-type hypersensitivity (DTH) response to the vaccine than did a trace amount of CT alone. In parallel with the in vivo response, normal peritoneal macrophages that were incubated in vitro with the vaccine and the CT-containing CTB, induced a higher adenylate cyclase activity and a greater ability to transfer DTH response into naive recipient mice than did the macrophages incubated with the vaccine and CT. The treatment of macrophages with the vaccine and CTB failed to induce either adenylate cyclase or DTH response. From these results, the mechanism by which CTB and a trace amount of CT enhance immune responses synergistically could be explained by the enhancement of the CT action on macrophages or by the efficient binding of a trace amount of CT to antigen-presenting cells in the presence of a relatively large amount of CTB, resulting in enhanced cyclic AMP formation followed by enhanced antigen presentation.

Animals↗

PubMed1995

Antagonizing effects of a novel antipsychotic quinolinone derivative (OPC-14597) on dopaminergic inhibition of neuronal activities in the nucleus accumbens.

1. The effects of a newly synthesized quinolinone derivative, 7-(4-[4-(2,3-dichlorophenlyl)-1-piperazinyl]butyloxy)-3,4-di hydro-2-(1H)- quinolinone (OPC-14597), an antipsychotic drug, on neuronal activities of the nucleus accumbens (Acc) were investigated in rats anesthetized with chloral hydrate using a microiontophoretic method. 2. Spikes elicited by stimulation of the parafascicular nucleus (Pf) of the thalamus were extracellularly recorded in the Acc neuron of chloral hydrate-anesthetized adult Wistar rats using a glass microelectrode attached along a seven-barreled micropipette, each of which was filled with dopamine, OPC-14597, SKF 38393 (D1 receptor agonist), quinpirole (D2 receptor agonist) and 2M NaCl. The drugs were microiontophoretically applied to the target neurons recorded. 3. Effects of the drugs on the Acc neurons activated monosynaptically by stimulation of the Pf were examined. Spikes elicited by Pf stimulation were inhibited by iontophoretic application of dopamine, SKF 38393 and quinpirole in a dose-dependent manner. 4. Microiontophoretic application of OPC-14597 alone affected the spikes elicited by the Pf stimulation in none of 26 neurons tested. However, the dopamine-, SKF 38393- and quinpirole-induced inhibition of the spike generation in the Acc neurons was antagonized during simultaneous application of OPC-14597. 5. The firing induced by iontophoretically applied glutamate was inhibited by dopamine, SKF 38393 and quinpirole, but not by OPC-14597. However, the dopamine-, SKF 38393- and quinpirole-induced inhibition of the glutamate-induced firing was also antagonized during simultaneous application of OPC-14597 in a dose-dependent manner in all neurons tested. 6. These findings suggest that OPC-14597 blocks dopaminergic inhibition of the Acc neurons receiving input from the Pf by acting on both D1 and D2 receptors located on the neurons.

Animals↗

PubMed1995

Optical neural device based on memory-type organic photoconductors.

A variable-sensitivity organic-photoconductive device has been developed by using a memory-type organic photoconductor. The device is composed of an input layer and a memory layer acting as a charge generation and a charge transport layer, respectively. A persistent high-sensitivity state, which corresponds to a modulation of synaptic weights in a neuron model, was obtained by blue light illumination. A photochemical reaction of thiomichler's ketone (TMK) in the memory layer was found to be responsible for the memory formation. As a potential application of this memory-type organic photoconductor to an optical neural device, 2-D pattern storage and calculations were performed successfully.

Animals↗

PubMed1995

Heat shock proteins in the human periodontal disease process.

The production of HSP by periodontopathic Gram-negative bacteria was examined by SDS-PAGE, two dimensional gel electrophoresis, and Western blotting using monoclonal antibodies against HSPs. Strains of Actinobacillus actinomycetemcomitans, Eikenella corrodens, Fusobacterium nucleatum, Prevotella intermedia, Prevotella nigrescens, Prevotella melaninogenica, and Treponema socranskii species produced HSP which reacted with anti-Yersinia enterocolitica HSP 60 and/or mycobacterial 65-kDA HSP monoclonal antibodies. It found that gingival homogenate samples from patients with adult periodontitis reacted with anti-human HSP were also found in a serum sample from a periodontitis patient. The present study suggests that HSPs are implicated in human periodontal disease process.

Adult↗

PubMed1995

Hemocompatible cellulose dialysis membranes modified with phospholipid polymers.

Hemocompatibility is one of the most important properties for hemodialysis membranes. For improvement of the hemocompatibility on a cellulose dialysis membrane, modifications with new blood-compatible phospholipid polymers were carried out. These methods included a direct grafting of the phospholipid monomer on the membrane surface, coating the membrane surface with a water-soluble graft copolymer composed of a cellulose backbone and phospholipid polymer as a branch, and covalent bonding with a reactive phospholipid polymer on the membrane surface. These modified membranes could reduce protein adsorption as well as complement activation and platelet adhesion on the surface without any adverse effects on the membrane performance.

Absorption↗

PubMed1995

Distribution of Porphyromonas gingivalis and Treponema denticola in human subgingival plaque at different periodontal pocket depths examined by immunohistochemical methods.

Localization of Porphyromonas gingivalis and Treponema denticola in different areas of subgingival plaque from advanced adult periodontitis patients was studied immunohistochemically using sensitive immunogold-silver staining and immunoelectron microscopy. Fourteen periodontally diseased teeth were extracted without damaging the subgingival plaque, fixed, and embedded. The subgingival plaque samples were sectioned according to four different pocket depths (0-2 mm, 2-4 mm, 4-6 mm and > or = 6 mm). Serial thin sections were stained using specific antisera to P. gingivalis or T. denticola and then with secondary antibody labelled with colloidal-gold. Cells of both P. gingivalis and T. denticola were predominantly found in subgingival plaque located at depths of more than 4 mm in periodontal pockets. T. denticola cells were found in the surface layers of subgingival plaque, and P. gingivalis were predominant beneath them. However, in the deeper subgingival plaque, the coexistence of P. gingivalis and T. denticola was observed. The present findings suggest that P. gingivalis and T. denticola play important roles in the pathogenicity of periodontal disease and provide the useful information for elucidating the pattern of colonization of microorganisms in the periodontal pocket.

Adult↗

PubMed1995

Reactive antibodies in sera from pubertal and adult gingivitis patients against various Porphyromonas gingivalis antigens.

This study was undertaken to determine the immunodominant antigens from Porphyromonas gingivalis which reacted with sera from patients of pubertal and adult gingivitis. The patients with cultivable P. gingivalis and the patients without cultivable P. gingivalis were compared by immunoblots. Fifty subjects participated in this study: 20 with gingivitis, 20 periodontally healthy, and 10 with adult periodontitis. The groups with gingivitis and healthy periodontium each contained 10 pubescent subjects and 10 adult subjects. P. gingivalis was isolated from 9 of 20 patients with gingivitis and from all of 10 with periodontitis by culture study. Approximate molecular weight 43 KDa fimbriae antigen, 57, 53, 46, 28 KDa antigens from outer membrane, and 57, 44, 40, 18.5 KDa antigens from sonicated extracts of P. gingivalis reacted significantly more frequently with sera from the P. gingivalis culture-positive gingivitis patients than with sera from the culture-negative patients by Fisher's exact test. A molecular weight 75, 31 KDa antigen from outer membrane and a 46 KDa antigen from sonicated extract were immunodominant in sera from adult patients with periodontitis. These findings indicate that the specific antigens which reacted with sera from P. gingivalis culture-positive patients are markers of infection with P. gingivalis. Additionally, reactivity to antigens were slightly different between sera from patients with gingivitis and those from patients with periodontitis.

Adhesins, Bacterial↗

PubMed1995

Cloning and expression of a neutral phosphatase gene from Treponema denticola.

We have isolated and characterized a neutral phosphatase gene, phoN, from Treponema denticola ATCC 35405. The gene was isolated from a T. denticola clone bank constructed in the medium-copy-number plasmid vector pMCL19. Subcloning and nucleotide sequencing of the DNA insert from one phosphatase clone, pTph14, revealed that the activity corresponded to an open reading frame consisting of 1,027 bp coding for a 37.9-kDa protein. Hydrophobicity analysis indicated that the protein exhibits some hydrophobic regions. Indeed, partial purification of the phosphatase suggested that the enzyme was membrane associated both in T. denticola and in the Escherichia coli clone. The pH optimum of the enzyme, approximately pH 6.4, indicated that it corresponded to a neutral phosphatase activity from T. denticola. An examination of possible natural substrates for the enzyme suggested that this enzyme hydrolyzes nucleoside di- and triphosphates. Northern (RNA) blot analysis revealed that this phosphatase gene is not likely to be present in an operon structure.

Amino Acid Sequence↗

PubMed1995

Double-exponential curve fitting of isometric relaxation: a new measure for myocardial lusitropism.

New indexes for evaluation of isometric myocardial relaxation were proposed. In fully isometric and physiologically sequenced twitches, the time course of isometric force decline fitted well with Gompertz's double-exponential curve (r > or = 0.9995). We conformed the original equation to suit myocardial mechanics, i.e., F(t) = gamma 0 - gamma.exp [-alpha.exp (-beta t)] (t = 1, 2, ..., n), where F(t) denotes force as a function of time t. The gamma 0 and gamma relate to upper asymptote and force amplitude, respectively. Phase-plane analysis of F(t) revealed that alpha [3.56 +/- 0.67 (SD)] related to the phasic delay of relaxation onset but did not affect the F(t) vs. dF(t)/dt relation. The beta (0.127 +/- 0.021) and gamma were linearly related to negative dF(t)/dtmax; however, the terminal slope of the phase-plane diagram was governed by beta alone. The tau beta (0.081 +/- 0.017 s), a reciprocal of beta multiplied by sampling time, was practically independent of preload, total load, and muscle shortening. In isometric twitches, tau beta was substantially decreased by global ischemia, isoproterenol, and CaCl2 but increased by reperfusion. The alpha was independent of inotropic interventions but fell significantly during ischemia and was increased by reperfusion.

Animals↗