PubMed Health⌕ Search

Biomedical subjects

K Kon

Publications and source records attributed to K Kon.

At least 91 records · Page 5Linked to original sources
PubMed1987

Establishment and characteristics of five analbuminemic inbred strains of rats.

Five analbuminemic inbred strains of rats (AD/1, AD/2, AD/3, AD/4, AD/5) were established from Nagase analbuminemic rats (NAR). They showed no genetic differences in coat color, biochemical marker gene loci and skin grafting test. Their serum levels of total cholesterol, phospholipids, triglycerides, and beta-lipoproteins were compared with normal inbred strains (L) derived from Sprague-Dawley rats. Their plasma apoproteins were also examined. All inbred strains of analbuminemic rats showed hyperlipidemia progressing with age although there were slight variations in their lipid and apoprotein levels. These analbuminemic inbred strains of rats may be multigenic models of lipid metabolism abnormality.

Animals↗
PubMed1987

A novel method for measuring the erythrocyte deformability, under oscillatory shear stress.

A novel apparatus for detecting a subtle decrease in erythrocyte deformability was developed. The oscillatory shape change of erythrocytes was monitored under an oscillatory shear stress (modulating the oscillation frequency in the range of 9-90 dyn/cm2). The ellipsoidal deformation of intact erythrocytes perfectly followed the oscillatory force of up to about 2 Hz, but the diamide-treated cells showed a phase difference of the oscillatory deformation at 1.7 Hz.

Erythrocyte Deformability↗
PubMed1987

Erythrocyte deformation in shear flow: influences of internal viscosity, membrane stiffness, and hematocrit.

The effect of shear force (depending on shear rate and viscosity of extracellular medium) and hematocrit of RBC suspension on RBC deformation was studied quantitatively using a cone-plate rheoscope with various kinds of cells, ie, partially hemolyzed (PH) cells, density-fractionated intact cells, and diamide-treated cells. The deformation index (DI) of ellipsoidally deformed cells was shown to be a function of beta gamma eta ex(eta ex/eta in)alpha, where gamma eta ex is applied shear stress, eta ex and eta in are external and internal viscosities, respectively, and alpha and beta are adjustable parameters related to the membrane viscoelastic properties. The increase of suspension viscosity at higher hematocrits (Hts) generally enhanced the ellipsoidal deformation of cells, in the same manner as increasing the suspending medium viscosity of a diluted cell suspension. The suppressing effect on cell deformation appeared above a certain Ht. When intact cells were mixed with glutaraldehyde-treated, hardened cells, the ellipsoidal deformation of intact cells was disturbed. The suppression of deformation probably occurred through disturbance of laminar flow-lines around intact cells.

Blood Viscosity↗
PubMed1986

A contribution of calmodulin to cellular deformability of calcium-loaded human erythrocytes.

The effect of intracellular calcium on the deformability of human erythrocytes was studied with a rheoscope, especially in relation to the dynamic structure of membrane cytoskeleton. The appropriate calcium-loading and calcium-depletion were performed to intact erythrocytes with A23187 in potassium buffer. The total calcium content was varied in the range of 0.25 to 3 times as much as normal content, without complete ATP depletion and shape change (the reduction of mean cell volume and the condensation of hemoglobin due to dehydration were avoided). Increasing the intracellular calcium content by about 1.5 times of normal, the deformability was distinctly decreased, while calcium depletion did not affect the deformability. Reduced deformability of the calcium-loaded erythrocytes was restored by the treatment with calmodulin inhibitors, W-7 or trifluoperazine. However, such an effect by calmodulin inhibitors was not detected on normal or calcium-depleted erythrocytes. In conclusion, the interaction between calcium-calmodulin complex and cytoskeletal proteins may affect the membrane stiffness which is regulated through the change of the cytoskeletal structure, and contributes to the deformability of erythrocytes.

Calcium↗
PubMed1986

A ganglioside of rat ascites hepatoma AH 7974F cells. Occurrence of a novel disialoganglioside (GD1 alpha) with a unique N-acetylneuraminosyl (alpha 2-6)-N-acetylgalactosamine structure.

A novel disialoganglioside has been isolated from rat ascites hepatoma AH 7974F cells. Based on the results of sequential enzymatic hydrolysis and gas chromatography-mass spectrometry analysis of the methylated sugars, the structure was concluded to be (Formula: see text) Proton magnetic resonance spectra of the ganglioside have been obtained and peaks of protons were assigned based on the analytical results. This is the first report on the occurrence in mammalian cells of an example of this new series of gangliosides which has NeuAc linked to the C6 position of GalNAc of the gangliotetraosyl backbone. The present ganglioside was named GD1 alpha.

Animals↗
PubMed1986

Increase of ATP level in human erythrocytes induced by S-adenosyl-L-methionine.

The effect of S-adenosyl-L-methionine (SAM) on the ATP level, the morphology and the deformability of human erythrocytes was investigated and compared with that of adenosine. (i) Upon incubation with SAM, the ATP level increased considerably in fresh cells (in both young and old cells in similar extent) and in stored (partially ATP-depleted) cells. But the incubation with adenosine increased ATP level to a lesser extent. (ii) The incubation of stored cells with SAM hardly affected (or rather decreased) the IMP level, while that with adenosine remarkably increased IMP (and ITP). (iii) The morphology and the deformability of stored erythrocytes were well conserved in spite of the treatment with SAM, as compared with the treatment with adenosine. The echinocytic transformation was induced in old cells to some extent by SAM, while did not in young cells.

Adenosine↗
PubMed1985

Cell age-dependent changes in deformability and calcium accumulation of human erythrocytes.

The deformability of human erythrocytes was measured in a rheoscope, as a function of intracellular calcium content (varied with ionophore (A23187) and CaCl2) without complete ATP depletion and echinocytic transformation. Loading calcium into intact erythrocytes (calcium content: 16.8 mumol/1 packed cells = 1.48 amol per cell), the cell volume and energy charge gradually decreased. Further, the membrane fluidity of the lipid portion decreased without crosslinking of membrane proteins. A distinct transition from deformable to undeformable cells was observed by the rheoscope technique: i.e., 50% transition occurred at 40-50 mumol calcium/1 packed cells (= 3.5-4.0 amol per cell) and more than 90% above 100 mumol/1 packed cells (= 6.5 amol per cell) at a shear stress of 140 dyn/cm2. The deformable cells maintained their deformability to ellipsoidal disks independent of the average calcium content. The underformable cells, separated as high-density cells by density gradient centrifugation after calcium-loading, showed lower glucose-6-phosphate dehydrogenase activity than low-density-deformable cells; thus, the calcium-loaded, undeformable cells were presumably in vivo aged cells. The younger cells, fractionated as low-density cells from intact erythrocytes, were more deformable than aged cells. Upon calcium-loading, the younger cells restored their cell volume and deformability, while the aged cells, containing originally more calcium and less ATP, decreased their volume and became undeformable. Therefore, calcium accumulation by ionophore-CaCl2 takes place in preference to aged cells of lower energy metabolism, and leads to cellular dehydration and loss of deformability, due to condensed hemoglobin and altered membrane organization.

Adenosine Triphosphate↗
PubMed1985

Effect of the presence of hardened erythrocytes on deformation-orientation characteristics of normal erythrocytes in shear flow studied by the spin label method.

The effect of the presence of hardened red blood cells (HRBC) in a mixed suspension on the deformation-orientation characteristics of normal cells in flow is experimentally probed by the electron spin resonance (ESR) spin label method, using a phosphatidylcholine label which does not transfer between the cells. The average deformation-orientation of the normal cells is generally suppressed by the presence of HRBC to different degrees, depending upon the shape and the way the HRBC are prepared. The effects are qualitatively explained by disturbance of laminar shear flow due to the random tumbling of the HRBC.

Blood Flow Velocity↗
PubMed1985

Study of the effect of varying hematocrit on free deformation and orientation of erythrocytes in flow.

The electron paramagnetic resonance (EPR) spin label method was used to investigate the effect of varying hematocrit on the deformation and orientation behavior of erythrocytes in shear flow. The relative EPR spectral change due to flow, which we use as a measure of the average deformation and orientation of erythrocytes, was observed as a function of the hematocrit. The profile generally shows a rising and a declining phase with the maximum in-between. The position of the maximum with respect to the hematocrit and the level of the spectral change are influenced by the suspending medium viscosity, osmolarity, and depend upon modifications of the red cell properties such as the internal viscosity, area-to-volume ratio and membrane rigidity. Results show that there is an upper limit of free deformation and orientation of the cell for a given hematocrit value. A possible role of the cell-cell interaction is discussed in restricting the space around a cell which is required for free deformation and orientation. A significance of the findings is that the actual deformation and orientation of an ensemble of cells which give rise to the EPR spectral change in flow is determined not only by the single cell deformability but also by the way the cells interact with each other under a given fluid dynamic condition.

Blood Viscosity↗
PubMed1984

Incorporation rate of GM1 ganglioside into mouse brain myelin: effect of aging and modification by hormones and other compounds.

The turnover rate of GM1 ganglioside in myelin was examined reveal age-related alterations in the metabolic activity. Three different age groups of mice were given deuterium oxide, and myelin was prepared from cerebella at intervals of two weeks. GM1 was isolated from the total myelin gangliosides by high performance liquid chromatography. Deuterated sugar moieties of GM1 were determined by chemical ionization-mass spectrometry which provided prominent quasimolecular ions. This method made it possible to determine separately the incorporation of deuterium into internal and external galactoses as well as other components. The incorporation rate of GM1 into myelin was clearly shown to be decreased with advancing age. Lower incorporation of newly synthesized sialic acid into GM1 than that of other sugars may indicate reutilization of sialic acid at about 50%. The possibility of modification of the myelin metabolism by exogenous factors was examined by monitoring the incorporation rate of GM1 in animals treated with chemical agents. It was revealed that thyroxine enhanced the incorporation of GM1 into adult brain myelin, whereas propylthiouracil reduced the incorporation. Other chemicals, estradiol, S-adenosylmethionine and LM1 ganglioside, showed only minor effects on the myelin turnover.

Aging↗
PubMed1984

The absolute structures of rubeomycins A and A1 (carminomycins II and III) and rubeomycins B and B1 (4-hydroxybaumycinols A1 and A2).

The absolute configurations of rubeomycins A and A1 (corresponding to carminomycins II and III) and rubeomycins B and B1 (corresponding to 4-hydroxybaumycinols A1 and A2), except at the C-1" position, were determined by comparison of the optical rotations and other spectral data of rubeomycin derivatives with those of daunomycin and L-(+)-lactic acid.

Anthracyclines↗
PubMed1983

Alteration of rheological properties of human erythrocytes by crosslinking of membrane proteins.

The crosslinking of membrane proteins of human erythrocytes by diamide (diazene dicarboxylic acid bis(N,N-dimethylamide) ) was quantified by 4% polyacrylamide gel electrophoresis in 1% sodium dodecyl sulfate. The relation between the crosslinking of membrane proteins and erythrocyte functions (rheological and oxygen transporting) was quantitatively examined. (i) The crosslinking of membrane protein was induced by diamide, without changing the shape and the contents of intracellular organic phosphates (adenylates and 2,3-diphosphoglycerate). The intensity of spectrin 2 in SDS-polyacrylamide gel electrophoresis decreased proportionally to diamide concentration. The percentage decrease in spectrin 2 (using band 3 as an internal standard) was the most appropriate indicator for crosslinking ("% crosslinking'). (ii) The suspension viscosity of erythrocytes increased in proportion to the percentage of crosslinking, in the range of applied shear rates of 3.76-752 s-1. (iii) Erythrocyte deformability (measured by a high-shear rheoscope) was reduced by the crosslinking. The change was detectable even at 5% crosslinking. (iv) Rouleaux formation (measured by a television image analyzer combined with a low-shear rheoscope) was inhibited by the crosslinking. The inhibition was also sensitively detected at more than 5% crosslinking. (v) Hemoglobin in erythrocytes was chemically modified by higher dose of diamide (probably by the binding of diamide with sulfhydryl groups). Also the oxygen affinity of hemoglobin increased and the heme-heme interaction decreased. (vi) The reduction of the crosslinking of membrane proteins by dithiothreitol apparently reversed the intensity of spectrin bands in SDS-polyacrylamide gel electrophoresis and the erythrocyte functions (the suspension viscosity and the deformability), though not completely.

Azo Compounds↗
PubMed1983

The influence of deformation of transformed erythrocytes during flow on the rate of oxygen release.

The deoxygenation rates of transformed erythrocytes were compared with those of normal discocytes by both stopped-flow and continuous-flow methods. Echinocytic and spherostomatocytic transformations were induced by various anionic and cationic drugs, respectively, without altering the oxygen affinity of haemoglobin, the cell volume or the membrane fluidity. The echinocytic transformation reduced the deoxygenation rate at slow-flow velocities (50 cm/sec), as detected by the continuous-flow method. However, at higher flow velocities (150 cm/sec) the rate was similar to that seen in normal discocytes. A close correlation between the degree of echinocytosis, the retardation of deoxygenation rate and the increase of suspension viscosity were observed. Microscopic observation of flowing erythrocytes revealed that the echinocytes scarcely deformed at the slower flow velocity, but clearly deformed at the higher flow velocity to various shapes resembling the flowing discocytes. Transformation to spherostomatocytes had no effect on the deoxygenation rate, which was comparable with that of the discocytes, and even the higher flow force did not induce any deformation. The retarded deoxygenation and the increased viscosity of echinocytes was probably due to an augmented stagnant layer around the cells (i.e. an increase of the hydrodynamic effective volume); this layer was reduced when the echinocytes were deformed with increasing flow force.

Blood Flow Velocity↗
PubMed1983

Kinetics of rouleaux formation using TV image analyzer. II. Rat erythrocytes.

With the use of a rheoscope combined with a TV image analyzer, the kinetics of specific pathogen-free rat erythrocyte aggregation was studied. Under certain conditions (gamma 7.5 s-1, hematocrit 0.36%, in own plasma, at 25 degrees C) one-dimensional aggregates (rouleaux) were formed without the development of three-dimensional aggregates, perhaps because of very low concentration of gamma-globulin. The observed phenomena could be explained by 1) the erythrocyte sedimentation and 2) the rouleaux formation. The time courses, of the biphasic change in erythrocyte count and of the increments in total area and in the area/count, were successfully simulated by a kinetic model of linear polymerization, assuming a sedimentation rate constant and an association rate constant. Further, a Poissonlike distribution of the length of rouleaux was shown, as predicted theoretically on the basis of the same kinetic model.

Animals↗
PubMed1983

Protective effect of alpha-tocopherol on the morphological and rheological changes of rat red cells.

The effect of alpha-tocopherol on the rheological properties of rat red cells was studied. The suspension viscosity of red cells increased, as the alpha-tocopherol content in red cells decreased. The red cells gradually transformed to echinocytes in isotonic solution dependent on the alpha-tocopherol content. The unique correlations among the viscosity, the transformation, and alpha-tocopherol content were observed. It was shown that the increased suspension viscosity of alpha-tocopherol-deficient cells could have arisen from the difficulty of echinocytes to undergo high shear deformation. The possible mechanism is discussed.

Animals↗
PubMed1983

Spin label study of erythrocyte deformability. III. Further characterizations of electron spin resonance spectral change in shear flow.

It is demonstrated that the change in the spin label ESR spectrum induced by shear flow reflects the whole cell deformation as a function of the cell surface area-to-volume ratio (s/v), the morphology and intracellular viscosity. Since the effect of the change in the membrane mechanical property on the ESR spectrum has been described previously, the spin label ESR spectrum is now shown to contain full information concerning the whole cell deformability which is determined by the major intrinsic and extrinsic properties of the red blood cells. The result of microphotographic observations shows also that the cells in the flow are elongated and aligned approximately along the flow direction to an increasing extent as the cells flow near the surface of the flat channel walls. Thus, the entire observation confirms the view that the ESR spectral difference-shear rate profile is closely related to the elongation ratio shear rate characteristics obtained by other (optical) methods.

Blood Viscosity↗
PubMed1982

Functional impairments of human red cells, induced by dehydroepiandrosterone sulfate.

A study has been made on the incorporation of dehydroepiandrosterone sulfate (DHAS), one of the most abundant adrenal C-19 steroids, into human red cells, and of the resulting effects on red cell functions. 1. DHAS was incorporated into red cell membrane mainly by a partition mechanism: The apparent partition constant was small ([DHAS]cell/[DHAS]free = 1.34), indicating that DHAS in red cells would be easily removed by dilution. 2. At least part of the DHAS taken up was apparently bound to band 3 protein and thereby was able to inhibit the exchange of intracellular and extracellular SO4(2-) (Ki = 70 micro M). 3. Using a fatty acid spin label, it was established that the presence of DHAS in lipid bilayer of the membrane increased the acyl chain motion in the middle portion of the membrane. 4. DHAS induced echinocytosis of red cells. It is suggested that the increase in the viscosity of red cell suspension, the decreased deformability and the decrease in the deoxygenation rate of hemoglobin in the presence of DHAS probably reflect the presence of echinocytes. 5. In the presence of plasma proteins, the incorporation of DHAs into red cells was remarkably suppressed.

Blood Viscosity↗