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Biomedical subjects

K Kon

Publications and source records attributed to K Kon.

At least 109 records · Page 6Linked to original sources
PubMed1980

Characterization of hyperlipidemia in Nagase analbuminemia rat (NAR).

The mutant analbuminemia rat (NAR) was recently reported by Nagase (1) to spontaneously develop hypercholesterolemia. A detailed lipid analysis was carried out to characterize the hyperlipidemia. The concentrations of major phospholipids as well as cholesterol were increased in plasma, whereas the triacylglycerol level remained unchanged. Free fatty acid and lysophosphatidylcholine levels, on the contrary, declined. The liver lipids were not accumulated, but appeared to be depleted.

Animals↗
PubMed1980

Functional restoration of ACD-blood by pyrodoxal 5'-phosphate.

Successful application of pyridoxal 5'-phosphate (PLP) to restore the oxygen transport function of ACD-stored blood is described. PLP is readily incorporated into ACD-erythrocytes by both carrier-mediated transport (in which ATP may participate) and passive diffusion. Plasma proteins (up to 2.5%) and inorganic phosphate (up to 40 mM) do not affect the incorporation of PLP, though more than 25 mM inorganic phosphate is necessary for the maintenance of ATP levels. Increasing the PLP concentration and/or decreasing the packed cell volume in the medium, increases the incorporation of PLP. Incubation of erythrocytes with PLP at pH 7.0 is most suitable for incorporation of PLP and the maintenance of ATP levels. PLP incorporated into erythrocytes restores the oxygen transport function of the ACD-erythrocytes, though decreased haem--haem interaction is observed. A procedure for the clinical application of PLP-loaded erythrocytes is suggested.

Adenosine Triphosphate↗
PubMed1980

A method for studying oxygen diffusion barrier in erythrocytes: effects of haemoglobin content and membrane cholesterol.

1. In order to study the kinetics os the oxygen egress from human red cells in the 50 sec-20 min time range, an apparatus for measuring the oxygen dissociation process was constructed, combining a spectrophotometer with an oxygen electrode of quick response. 2. Starting from air-saturated haemolysate or red cell suspensions, the velocity of oxygen dissociation from oxyhaemoglobin (Vdiss) and of oxygen disappearance in the medium (Vobs) after addition of bakers' yeast (consuming the dissolved oxygen at the velocity of Vconsump) were recorded. A parameter (r) was defined as the ratio of two velocities, Vegress (the velocity of oxygen egress into the medium) and Vdiss, r identical to Vegress/Vdiss = (Vconsump -Vobs)/Vdiss. Vcomsump could be calculated by the Michaelis-Menten equation as follows, Vconsump = Vmax [O2]/(Km + [O2]), where Vmax was the maximal velocity of oxygen consumption of bakers' yeast. 3. The r value was always 1.0 for the haemolysate, but it was less than 1.0 for the normal red cells. Further, the oxygen dissociation curve of red cells obtained at higher Vmax was distorted, due to the non-equilibration between intra- and extracellular oxygen concentrations. 4. The r value was (i) independent of the amounts of the allosteric effectors (2,3-diphosphoglycerate and H+) but (ii) dependent on the haemoglobin contents and (iii) dependent on the amounts of the membrane cholesterol. Therefore, the r value reflected only the process of the oxygen diffusion but not the "chemical reaction' rate. The "barrier' of the oxygen diffusion decreased at lower haemoglobin contents, but increased at higher cholesterol contents in the membrane.

Biological Transport↗
PubMed1979

The decreased membrane fluidity of in vivo aged, human erythrocytes. A spin label study.

The decreased membrane fluidity of the in vivo aged, human erythrocytes is found, by monitoring the electron paramagnetic resonance (EPR) spectra of fatty acid spin labels incorporated into the membrane. In addition, the decreased cell sizes and the decreased cholesterol and phospholipids contents, without significant changes of the quantity of the membrane proteins, also the decrease of ATP and 2,3-diphosphoglycerate and the increase of ADP and AMP, in the aged cells, were observed. Further the functional impairments of the aged cells, i.e. the increased oxygen affinity and the decreased deformability, were shown. On the basis of these quantitative data, the alteration of the protein-lipid organization, due to decreased lipid/protein ratio, the modified protein-lipid interaction and/or the influences of the diminished ATP content, is suggested to contribute towards the decreased membrane fluidity of the in vivo aged erythrocytes.

Adenine Nucleotides↗
PubMed1979

A kinetic measurement of red cell deformability: a modified micropipette aspiration technique.

A kinetic measurement of the red cell deformability is developed, modifying the micropipette aspiration technique of BRAASCH (1971). The sedimented human red cells on a slide-glass are individually aspirated into a micropipette by negative pressure (delta P), and the decreasing "velocity (v)" of the applied electric current, due to the aspirating cell, is taken as a measure of the "easiness" of the cell to enter into the small orifice of the micropipette (inner diameter, 2 R congruent to 3 micrometer). An empirical relation, v infinity (pi r2) . (delta P) . ("deformability"), is obtained. In order to test the validity of the method, some factors influencing the deformability are studied: i.e., the "velocity" decreases as lowering temperature; the "velocity" of the glutaraldehyde-pretreated cells and of both in vivo and in vitro aged cells decreases. Therefore, the parameter, "velocity (v)," reflects the deformability well. In addition, if a few assumptions could be allowed, v would be related to the Young's modulus of the membrane.

Erythrocyte Aging↗
PubMed1977

Effect of nitric oxide on the oxygen transport of human erythrocytes.

The oxygen dissociation curve of partially NO-liganded hemoglobin of human erythrocytes is measured. As the percentage of NO ligation increases, the affinity of nonliganded hemoglobin for oxygen increases and the heme-heme interaction decreases; furthermore, methemoglobin is formed. Therefore, NO affects the oxygen transport function of hemoglobin, decreasing the oxygen supply to peripheral tissues, because of (1) simple diminution of the available hemoglobin by the tightly bound NO, (2) the high affinity of hemoglobin for oxygen, and (3) the inevitable formation of methemoglobin.

Erythrocytes↗
PubMed1977

Chemical ionization and electron impact mass spectra of oligosaccharides derived from sphingoglycolipids.

Chemical ionization (CI) mass spectra with isobutane and ammonia for the oligosaccharides obtained from sphingoglycolipids were compared with their electron impact (EI) mass spectra. The oligosaccahride moieties were liberated from the parent glycolipids and were further reduced with sodium borohydride. They were analyzed as their permethyl peracetyl and pertrimethylsilyl derivatives. In the CI spectra, peaks corresponding to QM+ and/or [M-59]+ were observed in all of the peracetylated oligosaccharides examined. In CI with ammonia as the reagent, H+ was transferred to nitrogen-containing saccharides to produce [MH]+ and NH4 was transferred to nitrogen-free saccharides to yield [M+NH4]+ as QM+. Non-reducing ends yielded very intense peaks in CI spectra. On the other hand, the reduced end, glucitol, produced rather prominent peaks in EI spectra. Fragment ions due to cleavage of glycosidic bonds were major ones under the CI conditions, and they could be used for elucidating the sugar sequence in the oligosaccharides. An additional characteristic feature in the CI spectra was that ions due to scission of hexosaminyl glycosidic linkages were observed with very high intensities.

Carbohydrates↗
PubMed1976

Existence of glucosaminyl lactosyl ceramide (amino CTH-I) in human erythrocyte membranes as a possible precursor of blood group-active glycolipids.

A novel glycolipid containing N-acetylglucosamine (lacto-N-triose II ceramide, Amino CTH-I) was isolated as a minor component from the ceramide trihexoside fraction of human erythrocyte lipids. This glycolipid was purified by column chromatography and preparative high-speed liquid chromatography on Iatrobeads. Its structure was found to be N-acetylglucosaminyl(beta 1-3)galactosyl(beta 1-4)glucosyl-(beta 1-1)ceramide, so it is suggested that it may be a precursor of paragloboside and blood group-active glycolipids.

Amino Acids↗
PubMedDate not supplied

MR findings in Tay-Sachs disease.

OBJECTIVE: MR and CT findings in two patients of Tay-Sachs disease are reported. MATERIALS AND METHODS: In two patients of Tay-Sachs disease, MR and CT studies were conducted in the early phase (11 and 10 months of age, respectively) and one was followed-up with MR in the late phase at the age of 5 years and 8 months. Six MR studies on this disease (including 3 other cases documented in the literature) were reviewed and correlated with the pathological phases of this disease. RESULTS: MRI findings drastically changed during the phases of disease process in one case. In the early phase, T2-weighted MR images demonstrated hyperintensity in both basal ganglia and thalamus. MR images obtained in the late phase demonstrated markedly advanced brain atrophy and diffuse white matter lesions, which were hyperintense on the T2-weighted images. T1-weighted images exhibited hyperintensity in the basal ganglia, thalamus, and along the cortical layer of the cerebrum, which appeared to by hypointense on T2-weighted images. CONCLUSION: MR was apparently superior to CT in clearly delineating lesions of this disease. These abnormal signal intensities in the late phase may reflect the pathological findings, marked accumulation of GM2 ganglioside in the basal ganglia and thalamus and along the cerebral gray matter.

Brain↗