During the course of studies on natural occurrence of sphingosine base in brain, cationic glycosphingolipids bound to carboxymethyl-Sephadex and eluted with triethylamine in organic solvents were ...isolated and characterized. Four classes of compounds were identified: (i) plasmalopsychosine-A and -B; (ii) glyceroplasmalopsychosine; (iii) glycosphingolipids having de-N-acetyl-hexosamine, e.g., de-N-acetyl-Lc3Cer; (iv) glycosylsphingosine, i.e., lysoglycosphingolipid. Only two kinds, galactosylsphingosine (psychosine) and lactosylsphingosine, were found to occur naturally in brain. All these compounds were isolated from extract of brain white matter. Their occurrence, quantity, and distribution pattern differ from one species to another. Their quantity is much lower than that of regular acidic and neutral glycosphingolipids. They may interact with regular glycosphingolipids in glycosphingolipid-enriched microdomains to elicit signal transduction, to modify cellular phenotype, although studies along this line are highly limited at this time.
Metabolism of sulfolipids in isolated renal tubules from rat Nagai, Ken-ichi; Tadano-Aritomi, Keiko; Iida-Tanaka, Naoko ...
Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology,
03/2005, Volume:
140, Issue:
3
Journal Article
Peer reviewed
Proximal-rich tubules were prepared from rat kidneys by using collagenase treatment. The isolated rat renal tubules were compared with the intact kidney on the following characteristics. (1) ...Composition of the sulfoglycolipid. (2) Sulfoglycolipid metabolism based on incorporation of
35Ssulfate or some properties of sulfoglycolipid metabolism, including the activities of anabolic and catabolic enzymes. The results indicated following characteristics of the isolated renal tubules in comparison to the kidney in vivo. (1) The sulfoglycolipid compositions are qualitatively similar, except that the content of glucosyl sulfatide, Gg
3Cer II
3-sulfate, and GM4 was slightly higher in the isolated tubules. (2) The apparent half-lives (15–55 min) of sulfoglycolipids in the isolated tubules could indicate the existence of a rapid turnover pool of these lipids. (3) The sulfotransferase and sulfatase activities related to sulfoamphiphiles in the renal tubule were similar to those reported for the whole kidney. Based on the above criteria, we conclude that the isolated rat renal tubule should be a useful metabolic system for clarification of the short-term physiological events, up to 90 min, of proximal tubular sulfoglycolipids. By using the present system, we showed that biosynthesis of the renal total sulfoglycolipid was significantly elevated in rats deprived of water for 24 h.
A highly sensitive method for quantification of sialic acids in gangliosides was developed. The sialic acids, released by hydrolysis of gangliosides, were converted to fluorescent derivatives with ...1,2-diamino-4,5-(methylenedioxy)benzene (DMB) and separated on a reversed-phase C18 column with an isocratic elution. As little as 0.1–1.0 nmol of sialic acid in ganglioside was quantified. The use of acetate buffer instead of water in the mobile phase could prevent damage on the column and reduce background peaks derived from the reagents. When gangliosides were subjected to acid hydrolysis, the velocity of hydrolysis varied depending on their structures and a part of the sialic acid liberated decomposed with prolonged heating time. Therefore gangliosides were hydrolyzed by Arthrobacter ureafaciens neuraminidase in the presence of sodium cholate after addition of an internal standard. For the internal standard, GM3 with N-propionylneuraminic acid (GM3(NeuPr)) was synthesized from GM3(NeuAc) by N-deacylation followed by N-propionylation. Folch partition was used to decrease lipophilic materials included in the sample, and the sialic acids released were recovered from the upper phase. The present method has a satisfactory sensitivity in the simultaneous quantification of NeuAc and NeuGc in purified gangliosides as well as in crude lipid fractions containing a variety of gangliosides.
An advanced microchannel heat exchanger (MCHE) with S-shaped fins can realize high heat transfer performance and reduced pressure drop performance. Simulation calculations by the three-dimensional ...computational fluid dynamics (3D-CFD) code were examined for a MCHE with S-shaped fins using carbon dioxide (CO(2)) as the working fluid in the wide range of inlet pressure and temperature conditions, which are from subcritical conditions to supercritical conditions. From the numerical results, a Nusselt number correlation was obtained using multivariable analysis. The standard deviation between the correlation and numerical results was 6.1%. A MCHE test piece with the same flow channel configuration as that for numerical simulation was manufactured, and experimental verification of the thermal-hydraulic performance of the test piece was examined. The heat transfer performance of the test piece was calculated using the Nusselt number correlation and was compared with experimental results. Numerical heat transfer performance showed good coincidence with a deviation of 2.5%. The conditions used in numerical simulation include the conditions of a recuperator and an intermediate heat exchanger of CO(2) gas turbine cycle. Using the obtained Nusselt number correlation, designing these heat exchangers becomes easier.
This paper presents experimental study on transport mechanism of thermohydraulic instability, which may occur in natural circulation boiling water reactor during startup. The research was carried out ...using a natural circulation experimental loop featuring twin parallel boiling channels with chimney assembly. The experiments were performed with the pressure range of 0.1 to 0.7MPa and maximum heat flux of 577kW/m
2
. The objective of the study is to formulate thermohydraulic stability maps required for determining rational startup procedure of the reactor, in which the instability could be prevented. The study clarified that the flow modes during startup consist of the following sequence: (1) single-phase flow, (2) geysering, (3) oscillation due to hydrostatic head fluctuation, (4) density wave oscillation, (5) transition oscillation, and (6) stable two-phase flow. The main findings of the experiments are as follows: First, low amplitude geysering still occurs at 0.7 MPa under lower heat flux and high inlet subcooling. Second, stable two-phase natural circulation is achieved with system pressure as low as 0.2 MPa, under medium heat flux, and subcooling lower than 5 K. Third, oscillation due to hydrostatic head fluctuation only occurs under atmospheric condition. Finally, thermohydraulic stability maps and rational startup procedure are formulated.
This paper presents experimental study on transport mechanism of thermohydraulic instability, which may occur in natural circulation boiling water reactor during startup. The research was carried out ...using a natural circulation experimental loop featuring twin parallel boiling channels with chimney assembly. The experiments were performed with the pressure range of 0.1 to 0.7 MPa and maximum heat flux of 577 kW/m2. The objective of the study is to formulate thermohydraulic stability maps required for determining rational startup procedure of the reactor, in which the instability could be prevented. The study clarified that the flow modes during startup consist of the following sequence: (1) single-phase flow, (2) geysering, (3) oscillation due to hydrostatic head fluctuation, (4) density wave oscillation, (5) transition oscillation, and (6) stable two-phase flow. The main findings of the experiments are as follows: First, low amplitude geysering still occurs at 0.7 MPa under lower heat flux and high inlet subcooling. Second, stable two-phase natural circulation is achieved with system pressure as low as 0.2 MPa, under medium heat flux, and subcooling lower than 5 K. Third, oscillation due to hydrostatic head fluctuation only occurs under atmospheric condition. Finally, thermohydraulic stability maps and rational startup procedure are formulated.
A novel plasmal conjugate of glycosphingolipid having cationic lipid properties was isolated from the white matter of bovine brain. Linkage analysis of galactosyl residue by methylation, liquid ...secondary ion, and electrospray ionization mass spectrometry of intact and methylated derivatives, and by (1)H- and (13)C-NMR spectroscopy, identified the structure unambiguously as an O-acetal conjugate of plasmal to the primary hydroxyl group of glycerol and to the 6-hydroxyl group of galactosyl residue of beta-galactosyl 1-->1 sphingosine (psychosine). This novel compound is hereby termed "glyceroplasmalopsychosine"; its structure is shown below (see text).
To establish techniques for producing somatic and germline chimeric chicken by transferring blastodermal cells fused with electroporation.
Stage-X blastodermal cells isolated from freshly laid ...fertile unincubated white Leghorn and Rhode Island red chicken eggs were fused with electroporation. The treated cell suspension was transferred to the recovery medium (DMEM containing 10% FBS) and was injected into the subgerminal cavity of recipient unincubated embryos (stage X).
Of 177 recipient embryos injected with the fusing blastodermal cells, 6 (3.4%) survived to hatching. Somatic chimerism was examined in the melanocyte of the feather. The presence of feathers originating from the donor cell was observed in 1 bird (16.7%) out of the 6 hatched birds. After 21 days of incubation two birds out of five embryos were subjected to polymerase chain reaction (PCR) analysis for W-chromosome-specific DNA for each tissue. One bird possessed W-chromosome-specific DNA in the stomach, and the other exhibited the same DNA in the left and right gonads and other tissues, but not the stomach.
Recipient embryo having electrofused blastodermal cells yields somatic and germline chimeric chickens more successfully.
The purpose of the study is to experimentally investigate driving mechanism of major instabilities simulated in a natural circulation experimental loop, under a predetermined range of system ...operating pressure and inlet subcoolings. Pressure range of 0.1 up to 0.7MPa, input heat flux range of 0 up to 577kW/m2, and inlet subcoolings of 5, 10 and 15K respectively, are applied in the experiments. The objective of the study is to formulate a rational startup procedure, in which major thermohydraulic instabilities can be detected and prevented. The study clarifies that four (4) kinds of thermohydraulic instability might occur even up to a higher pressure of 0.7MPa. The instabilities' sequence is as follows: (1) geysering induced by condensation accompanied by flashing, (2) oscillation induced by hydrostatic head fluctuation, (3) density wave oscillations, and (4) flashing accompanying those instabilities. The experiments confirmed that the geysering region gets narrower and suppressed with the increased system pressure. With chimneys, natural circulation can be achieved reliably and more easily. However, the flashing in the chimney cannot be avoided at low system pressure. Stable two-phase natural circulation can be established if the system pressure is increased beyond 0.7MPa, after the high frequency density eave oscillation thoroughly suppressed. The experiments were analyzed based on frequency domain of each instability phenomenon.
The objective of this paper is to develop a method for flow regime identification by using reflected ultrasonic intensity. This study applies ultrasonic signal and measures strength of the reflected ...signal from bubbles in bubbly flow, slug flow, annular flow and single-phase flow. This study is performed in an air-water circular pipe with a diameter of 50 mm. The total height of this apparatus is 7 m. The reflected ultrasonic intensity values from gas phase in wall-peak and core-peak bubbly flow, slug flow, annular flow and single-phase are obtained. Summation patterns of the normalized positive ultrasonic intensity of each repetition in 3 seconds of core-peak bubbly flow, wall-peak bubbly flow, slug flow, annular flow and single-phase flow in the three areas, the area at near the ultrasonic intensity probe, the area at the middle of pipe and the area at far from the ultrasonic intensity probe, are shown and discussed in this study.
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