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Biomedical subjects

A Ishihara

Publications and source records attributed to A Ishihara.

At least 217 records · Page 12Linked to original sources
PubMed1987

Lateral diffusion of proteins in membranes.

Membrane protein lateral diffusion can be constrained in several ways: Diffusion can be slower than that predicted for a simple, fluid lipid bilayer; diffusion can be confined to certain regions within the total membrane; and diffusion may not be equally probable in all directions, i.e. it may be anisotropic. We know that protein diffusion is reduced by increasing concentrations of membrane proteins and by interactions of the diffusant with structure(s) peripheral to the membrane. The molecular nature of such peripheral constraints has been difficult to pinpoint, but attention is now being directed to the extracellular matrix in addition to the membrane-associated cytoskeleton. There are many proteins that are confined to lateral domains in differentiated, isolated cells and in cells organized into tissue. The mechanisms that maintain such inhomogeneous distributions should be elucidated in the next few years. Whether lateral diffusion of membrane proteins over distances of a few micrometers is usually isotropic or anisotropic will be ascertained in the near future using imaging methods combined with photobleaching.

Diffusion↗
PubMed1987

Changes in central somatosensory pathways accompanying reaction movements.

The changes within central somatosensory pathways accompanying reaction movements were examined by subtracting the peak latency of the major response from the cervical area (14 msec.) from that of the primary cortical response (20 msec.) and also measuring the CNV which is dependent on the direction of the subject's attention and level of arousal. These parameters were measured before (at rest), during fast and slow reaction movements, and mental readiness to act. Analysis showed that the difference in N20-N14 potential latencies is the shortest during fast reaction movements and is shorter during movement tasks than during mental readiness and intention to act. Moreover, we confirmed that the CNV amplitudes are significantly higher during fast than during slow reaction movements and also that the difference in N20-N14 potential latencies decreases as the CNV amplitude increases. Accordingly, from the present results and a series of studies conducted by others, it may be concluded that not only are the changes in the central motor area confirmed by the movement-associated cerebral potentials but also those in the central somatosensory area occur prior to reaction movements.

Adult↗
PubMed1987

[A case report of adenolipoma of the breast].

A rare case of breast adenolipoma is presented. A 49-year-old, otherwise healthy woman had a tumor of the left breast for approximately 25 years. Ultrasound mammography demonstrated a well-demarcated, high echoic mass with islands of a low echoic area in the center of the tumor. The well-defined, oval, soft tumor, measuring 7 x 5 x 3.5 cm in size, was surrounded by a thin capsule which was removed, and its yellow cut surface was found to be mottled by greyish-white areas. Microscopically, the tumor was diagnosed as a breast adenolipoma consisting of fatty tissue interspersed with islands of glandular tissue. The findings of ultrasound examination on adenolipoma of the breast are described and its histogenesis was discussed.

Adenoma↗
PubMed1986

Electrophysiological findings in a family with congenital arteriohepatic dysplasia (Alagille syndrome).

Arteriohepatic dysplasia (Alagille syndrome) is a congenital cholestatic disease associated with ocular abnormalities. Three Japanese siblings, a 14-year-old girl, an 11-year-old boy, and a 9-year-old girl with this syndrome were studied. All three patients showed neonatal jaundice, hepatic dysfunction, characteristic facies, and psychomental retardation. The two sisters had cardiac murmurs. Ophthalmological examinations revealed that they had posterior embryotoxon, refractive error, retinochorodial degeneration, and electrophysiological abnormalities. The two sisters showed retinochoroidal degeneration and unilateral high myopia while the brother showed marked retinochoroidal degeneration with extensive pigment clumps. Visual fields showed moderate concentric contraction in the two sisters and marked concentric contraction in the brother. Amplitudes of the single flash electroretinogram were moderately reduced in the sisters, the test was nonrecordable in one eye and extensively reduced in the other eye of the brother. The electrooculogram was borderline in the elder sister and abnormal in the brother and younger sister. Visual evoked cortical potential (VECP) were abnormal in the high myopic eye in each of the two sisters. Ophthalmological findings including electrophysiological examinations may help to confirm the diagnosis of this multisystem familial disorder.

Adolescent↗
PubMed1986

Subdivision of flagellar genes of Salmonella typhimurium into regions responsible for assembly, rotation, and switching.

Three flagellar genes of Salmonella typhimurium (flaAII.2, flaQ, and flaN) were found to be multifunctional, each being associated with four distinct mutant phenotypes: nonflagellate (Fla-), paralyzed (Mot-), nonchemotactic (Che-) with clockwise motor bias, and nonchemotactic (Che-) with counterclockwise motor bias. The distribution of Fla, Mot, and Che mutational sites within each gene was examined. Fla sites were fairly broadly distributed, whereas Mot and Che sites were more narrowly defined. Local subregions rich in sites of one type were not generally rich in sites of another type. Among Che sites, there was little overlap between those corresponding to a clockwise bias and those corresponding to a counterclockwise bias. Our results suggest that within the corresponding gene products there are specialized subregions for flagellar structure, motor rotation, and control of the sense of rotation.

Alleles↗
PubMed1986

Postoperative left ventricular function in patients with mitral stenosis. The effect of commissurotomy and valve replacement on left ventricular systolic function.

Preoperative and postoperative left ventricular cineangiograms of 26 patients with mitral stenosis (MS) were analyzed to calculate left ventricular end-diastolic volume (EDV), end-systolic volume (ESV), stroke volume (SV), ejection fraction (EF) and systolic regional wall motion. Nine patients underwent commissurotomy (OMC group) and 17 patients underwent mitral valve replacement (MVR group). In both groups, postoperative EDV, SV and EF tended to increase, while ESV remained unchanged. In the OMC group, systolic wall motion of the left ventricle was found to be improved postoperatively, whereas systolic wall motion in the MVR group was found to be impaired postoperatively. The latter finding was assumed to be due to excision of the papillary muscles and chordae tendineae. Preservation of these structures is likely to be important for better postoperative functional recovery of the left ventricle.

Adult↗
PubMed1986

Partial purification and characterization of serum protease from tumor-bearing rats which cleaves type IV collagen.

Activity of neutral protease was increased in sera of rats bearing ascites hepatoma AH109A compared to those of normal rats. The protease was isolated from serum protein and partially purified approximately 1,150 times in specific activity after sequential column chromatography of hemoglobin affinity, lysine-Sepharose, Ultrogel AcA34 and TSK-gel G2000SW in that order. The protease fraction still seemed to contain at least two kinds of proteases, serine and cysteine protease. It had a molecular weight of 18-21 kilodaltons with broad optimal pH range of 7.0-9.0, maximum at 8.0. Intradermal injection of the crude preparation of the neutral protease fraction induced extravascular emigration of circulating tumor cells in vivo. Moreover, partially purified protease degraded pepsin-treated chains of bovine glomerular type IV collagen in vitro, but such an in vitro action of the protease was inhibited by an addition of soybean trypsin inhibitor or mercuric chloride. It failed to cleave salt-extracted rat skin type I collagen under the same digestive conditions for bovine type IV collagen. The serum neutral proteases of tumor-bearing host may play some cooperative roles during extravascular emigration of tumor cells by destruction of vascular basement membrane.

Animals↗
PubMed1985

Chromosome abnormalities in malignant histiocytosis.

Chromosome and pathologic studies were performed on two patients (a 12-year-old boy and a 62-year-old woman) with malignant histiocytosis (MH). Both patients had chromosome abnormalities in their neoplastic cells: the boy's karyotype was 45,Xp+,-Y,9p+,18q-, and the woman's 48,XX,+16, inv(1),mar(5),6p-,10p+,12q+,i(18q),+i(18q). The boy had typical clinical and pathologic findings of MH, and died without achieving remission by chemotherapy. At the initial stage the woman had the clinical and hematologic findings of MH. Chemotherapy was given, but had no beneficial effects. At the terminal stage the bone marrow (BM) biopsy and aspirate, and the autopsy findings, were consistent with those of non-Hodgkin lymphoma, diffuse large cell type, although some histiocytes or abnormal cells in monocyte-macrophage lineage remained in the BM and the autopsied lymph nodes. This study and a review of data on six other cases have failed to establish any specific chromosome changes in MH.

Adolescent↗
PubMed1985

A new method of evaluating the degree of stenosis using a multisensor catheter. Application of the pressure loss coefficient.

A new method of evaluating the degree of stenosis using the pressure loss coefficient is presented here. The pressure loss coefficient was obtained in patients with pulmonary or aortic stenosis by measuring the pressure and velocity of the blood simultaneously with a multisensor catheter. Although the pressure gradient across the stenosis was augmented by increasing the blood velocity with pharmacological loading, the pressure loss coefficient remained nearly constant. This confirmed that the pressure loss coefficient is more appropriate for evaluating the degree of stenosis than the pressure gradient, which depends on the blood velocity. The pressure loss coefficients obtained from the preoperative and postoperative catheterization data were compared to evaluate the effects of the surgical operation. A pressure loss coefficient of 15 was proposed as the critical value for the indication of operation.

Adolescent↗
PubMed1985

Chemotactic signaling in filamentous cells of Escherichia coli.

Video techniques were used to record chemotactic responses of filamentous cells of Escherichia coli stimulated iontophoretically with aspartate. Long, nonseptate cells were produced from polyhook strains either by introducing a cell division mutation or by growth in the presence of cephalexin. Markers indicating rotation of flagellar motors were attached with anti-hook antibodies. Aspartate was applied by iontophoretic ejection from a micropipette, and the effects on the direction of rotation of the markers were measured. Motors near the pipette responded, whereas those sufficiently far away did not, even when the pipette was near the cell surface. The response of a given motor decreased as the pipette was moved away, but it did so less steeply when the pipette remained near the cell surface than when it was moved out into the external medium. This shows that there is an internal signal, but its range is short, only a few micrometers. These experiments rule out signaling by changes in membrane potential, by simple release or binding of a small molecule, or by diffusion of the receptor-attractant complex. A likely candidate for the signal is a protein or ligand that is activated by the receptor and inactivated as it diffuses through the cytoplasm. The range of the signal was found to be substantially longer in a cheZ mutant, suggesting that the product of the cheZ gene contributes to this inactivation.

Aspartic Acid↗
PubMed1985

Separation of cephaloridine from the rat urine contaminated by feces and diet pellets in high-performance liquid chromatography. Pretreatment with strongly basic anion exchange resin following deproteinization.

In this study, a high-performance liquid chromatographic method including a treatment with ion exchange resin following a deproteinization treatment, was studied for determination of cephaloridine in the rat urine which was contaminated by pieces of feces and diet pellets. The solvent system used was 10% acetonitrile (v/v) in 0.1 M K2 HPO4-H3 PO4 buffer, pH 7.5, and this was isocratically eluted on a reversed-phase column of NOVA-PAK C18. The urine sample containing cephaloridine was deproteinized, treated with a strongly basic anion exchange resin of Dowex-1-Chloride, and then chromatographed. In comparison to the sample treated by the simple deproteinization, the residual substances after the deproteinization, which interfered the cephaloridine peak, were removed by the following treatment with Dowex-1-Chloride, as was confirmed using a three-dimensional computing spectrophotometric monitor. Thus, the present method is considered to be useful in determination of cephaloridine in such body fluids as urine in which many interfering substances are contained.

Animal Feed↗