[Investigation of myocardial protection during open heart surgery in infants with ventricular septal defect].
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Cardiac Surgical Procedures↗
Biomedical subjects
S Noji
Publications and source records attributed to S Noji.
Molecular oxygen controls nitrate transport of Escherichia coli nitrate-respiring cells.
Escherichia coli cells grown anaerobically in the presence of nitrate reduce the nitrate as a terminal electron acceptor in place of molecular oxygen by an induced respiratory-type electron transferring system residing in the inner membrane structure. When oxygen is introduced to a suspension of nitrate-respiring cells, the oxygen is immediately reduced preferentially and the cellular uptake of nitrate ceases abruptly. In contrast, we found that the cells exhibited no oxygen control on uptake of chlorate, a competitive substrate analogue, indicating operation of an oxygen-sensitive transport system specific to nitrate. This was further evidenced by the fact that chlorate inhibition of reduction of nitrate was brought about only when the transport of both chlorate and nitrate was facilitated by the aid of carrier-type chlorate (or nitrate) ionophore. We demonstrated that oxygen inhibition on reduction of nitrate was abolished within the cells treated by octyl glucoside resulting in a removal of permeability barrier specific to nitrate. We conclude that the transient control by molecular oxygen is primarily due to the inhibition of nitrate transport into the cytoplasmic side. Since nitrate induces the nitrate-respiring system, the repression of the nitrate reductase operon by molecular oxygen is consistently interpreted on the basis of the "inducer exclusion mechanism."
Aerobiosis↗
Spin label study of erythrocyte deformability. Ca2+-induced loss of deformability and the effects of stomatocytogenic reagents on the deformability loss in human erythrocytes in shear flow.
The Ca2+-induced loss of deformability in human erythrocytes and the recovery of the lost deformability by stomatocytogenic reagents were investigated by means of a new flow electron paramagnetic resonance (EPR) spin label method, which provides information on deformation and orientation characteristics of spin labeled erythrocytes in shear flow. The Ca2+-induced loss of deformability is attributed mainly to the increase in intracellular viscosity resulting from efflux of intracellular potassium ions and water (Gardos effect). Partial recovery of the lost deformability is demonstrated in the presence of stomatocytogenic reagents, such as chlorpromazine, trifluoperazine, W-7, and calmidazolium (R24571). The recovery can not be explained solely by suppression of the Gardos effect due to the reagents. Incorporation of an optimal amount of the reagents into the membrane appears to compensate for the membrane modification due to Ca2+ ions to restore a part of the lost deformability.
Calcimycin↗
Cloning and characterization of Streptococcus mutans LM7 plasmid pAM7.
The 5.6-kilobase-pair cryptic plasmid, pAM7, of Streptococcus mutans LM7 was cloned into Escherichia coli plasmids or a shuttle plasmid to examine whether the plasmid encodes bacteriocin. Plasmid pAM7 encoded proteins with molecular weights of 30,000, 22,000, and 12,000, but none of them appeared to be bacteriocin.
Bacterial Proteins↗
Cold shock hemolysis in human erythrocytes studied by spin probe method and freeze-fracture electron microscopy.
When human erythrocytes are osmotically stressed or chemically treated, they hemolyze on cooling below 10 degrees C (called cold shock). We have studied the effects of osmotic stress and cooling on the state of membrane by the spin-probe method and freeze-fracture electron microscopy. At room temperature, the membrane fluidity detected by 12-doxyl stearate spin probe showed a steady decrease with osmolality in hypertonic NaCl solutions up to 900 mOsm/kg, above which it remained unchanged. In hypertonic sucrose solutions, the electron paramagnetic resonance spectra showed an additional pair of absorptions, indicating development of regions, in the membrane, further immobilized than in NaCl solutions. Mobility of a cholesterol analogue probe, androstane, did not show change by hypertonicity, but the spectral intensity dropped at 1,200 mOsm/kg, probably due to formation of loose aggregates in the cholesterol phase. On cooling the osmotically stressed cells in NaCl solution, the isotropic rotational correlation time vs. inverse temperature plot of 12-doxyl stearate probe exhibited a step-wise discontinuity at approximately 10 degrees C, suggestive of a drastic transition in the state of the membrane. At about the same temperature, the freeze-fracture pattern of osmotically stressed cells revealed the development of large wrinkles and aggregation of membrane particles, in contrast to the case of the cells in isotonicity. Significance of these findings in understanding cold shock hemolysis is discussed.
Cold Temperature↗
Spin-label studies of erythrocyte deformability. IV. Relation of electron spin resonance spectral change with deformation and orientation of erythrocytes in shear flow.
Electron spin resonance (ESR) spectra of spin-labeled human erythrocytes in shear flow are simulated to derive semi-empirical relations of the ESR spectral change with deformation and orientation of the cells by using a modified theoretical model developed for deformation and orientation of liquid drops. The six observed spectra at different shear stress values were simultaneously simulated by adjusting only two parameters. One parameter can be related to the ratio of the internal to the external viscosity, and the other to the elastic property of the cell membrane. From these results we have derived a semi-empirical relationship between the average deformation index or the orientation angle with a spectral measure, which characterizes the spectral shape change induced by shear stress. Thus, it becomes possible to obtain improved quantitative information on the rheological behavior of red blood cells by using the spin-label ESR method.
Electron Spin Resonance Spectroscopy↗
Interactions between retinyl phosphate and bivalent cations.
In the presence of Mn(II) ions, the u.v. absorption spectrum of retinyl phosphate (Ret-P) solubilized in Triton X-100 micelles, phosphatidylcholine liposomes or rat liver microsomes exhibited a shift from the maximum of 330 nm to 287 nm. The effect of Mn(II) was reversed by adding EDTA or phosphate buffer. The same spectral change was found in the presence of poly-L-lysine in place of Mn(II) ions. The e.s.r. spectrum of Mn(II) in the presence or in the absence of Ret-P clearly showed that approx. 75% of the initial concentration of Mn(II) ions is bound to Ret-P when the molar ratio of Ret-P to Mn(II) ions is 4:1; no such binding occurred in the presence of retinol or retinoic acid. The appearance of two isosbestic points at 303 and 368 nm, in the presence of Mn(II) ions, suggests the existence of an equilibrium between an Mn(II)-bound monomer and an Mn(II)-bound dimer of Ret-P in Triton X-100 micelles. The same effect on the u.v.-absorption spectrum of Ret-P was also induced by Co(II), Cr(II), Zn(II) and Fe(II), but not by Mg2+ or Cu(II). The formation of the 'metachromatic complex' between Ret-P and Mn(II) or Co(II) inhibited the synthesis of retinyl phosphate mannose (Ret-P-Man) from exogenous and endogenous Ret-P and guanosine diphosphate [14C]mannose when bovine serum albumin was added after the metal ion. However, the order of addition did not influence Ret-P-Man synthesis in incubations containing MgCl2, which does not form the metachromatic complex with Ret-P. These results suggest that the bioavailability of proteins, polyamines and metal ions may control the extent to which Ret-P can be mannosylated in the intact membrane.
Animals↗
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↗
A spin-label study of the correlation between stomatocyte formation and membrane fluidization of erythrocytes.
Change in the membrane fluidity of human erythrocytes on transformation to stomatocytes was observed by ESR spectroscopy using 12-doxyl stearic acid or its methyl ester as a probe. When the transformation to stomatocytes was induced by four qualitatively different methods, i.e. (a) addition of cationic amphiphilic agents such as chloropromazine, tetracaine, chloroquine or primaquine, (b) addition of Triton X-100, a non-ionic detergent, (c) lowering the pH, and (d) depleting membrane cholesterol, membrane fluidization was always observed. This indicates the existence of a close correlation between stomatocyte formation and increase in the membrane fluidity. Furthermore, since the stomatocytes fixed by diamide treatment exhibited membrane fluidization only in the presence of the reagent, the enhanced membrane fluidity was a direct consequence of the reagent interacting with, and changing the state of, the lipid bilayer itself, and not through the influence of some structural alteration of spectrin. These results provide experimental support for the theoretical prediction made by Brailsford et al. [J. theoret. Biol. 86, 531 (1980)]. Plausible mechanisms for the discocyte-stomatocyte transformation are discussed.
Chlorpromazine↗
[Nursing of epileptic patients and nursing personnel--through interactions with an epileptic patient with personality changes].
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Epilepsy↗
Use of spin label and the flow-induced ESR spectral difference for studying erythrocyte deformation.
ESR spin-labeling method is expanded to measure the macroscopic visco-elastic properties of erythrocytes. A suspension of erythrocytes with an incorporated fatty acid spin label was forced to flow through a flat ESR sample cells, and the ESR spectral change caused by the shear flow was utilized to assess the cell deformability. Chemical cross-linking or heat denaturation of membrane proteins to make the cells less deformable without any morphological change was found to reduce the relative spectral difference (delta h/h). This result indicates that the spectral difference is related to the cell deformation that accompanies the orientation of the cells in the shear flow. In addition, the average decay time (tau av) for the spectral difference observed when the flow was abruptly interrupted became shorter with an increase in the degree of cross-linking or heat-denaturation abruptly interrupted became shorter with an increase in the degree of cross-linking or heat-denaturation at 49 degrees C. Since the observed tau av is much shorter than the expected rotational correlation time for the erythrocyte, the decay is attributed to the deformation recovery process. It is demonstrated that the measurements of both delta h/h and tau av by ESR spectroscopy give qualitative information on the viscosity and the elasticity of the cell membrane system.
Blood Viscosity↗
Spin label study of erythrocyte deformability I. Electron spin resonance spectral change under shear flow.
A spin labeling method in electron spin resonance spectroscopy (ESR) is applied for the first time to study the deformability of human red blood cells (RBC). ESR measurements of a RBC suspension incubated with a fatty acid spin label were performed, using a narrow-gap flat ESR sample cell under various flow shear stresses (tau). Remarkable changes were observed in ESR spectra with tau, indicating that RBC are oriented in such a way that the greater part of the membrane surface is aligned parallel to the ESR cell walls. The diamide-treated, hardened RBC, in which the biconcave discoid shape remains intact under no shear stress, exhibit a smaller ESR spectral change with tau than the intact, demonstrating that the present method can be used to assess the deformation of RBC occurring with flow orientation. In particular, the relative amplitude of an ESR difference spectrum may be used as a measure of the elongation of RBC. The conclusion is further supported by experiments using glutaraldehyde-treated or heat-denatured RBC. All these ESR results are in good agreement with the corresponding results obtained by several different methods. The present spin labeling technique is thus proven to be applicable for evaluating RBC deformability.
Electron Spin Resonance Spectroscopy↗
Achromobacter cycloclastes nitrite reductase. The function of copper, amino acid composition, and ESR spectra.
1. Dialysis against cyanide at pH 7 of Achromobacter cycloclastes nitrite reductase [EC 1.7.99.3] of a dissimilatory type led to the removal of about 50% of the copper from the enzyme molecule, with a concomitant decrease of the enzymatic activities. It was inferred that enzyme-bound copper atoms play an essential role in the catalytic activities of the enzyme. 2. The amino acid composition of the enzyme was determined after acid hydrolysis. 3. ESR spectra of the frozen solution and lyophilized powder of the nitrite reductase predominantly showed the presence of two kinds of copper: Type 1 Cu2+, which had narrow and sharp hyperfine splitting, and Type 2 Cu2+, which had broader hyperfine splitting. The bond between the oxidized enzyme and nitrite seems to be ionic.
Alcaligenes↗