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We observed the Cygnus Loop with XMM-Newton (9 pointings) and Suzaku (32 pointings) between 2002 and 2008. The total effective exposure time is 670.2 ks. By using all of the available data, we intended to improve a signal-to-noise ratio of the spectrum. Accordingly, the accumulated spectra obtained by the XIS and the EPIC show some line features around 3 keV that are attributed to the S He$\beta$ and Ar He$\alpha$ lines, respectively. Since the Cygnus Loop is an evolved ($\sim$10,000 yr) supernova remnant whose temperature is relatively low ($, Comment: 12 pages, 9 figures, accepted for publication in PASJ

X-ray measured metal abundances of the rim of the Cygnus Loop are known to have two patterns. One, seen at narrow regions along the outermost edge, is 0.5-times the solar value, and the other, seen in the remainder of the rim, is 0.2-times the solar value. While the former is “normal”, as the ISM around the Cygnus Loop, the latter is unexpectedly depleted, and its origin has been puzzling. We have been tackling this issue by observing the rims with X-ray observatories. So far, the normal abundance was observed only at regions where no cloud-shock interactions are suggested. On the contrary, based on our recent Suzaku observations, we find the normal abundance at the southeastern rim where cloud-shock interactions are evident. The spatial variation of the abundance there is similar to that in other normal abundance rims: the normal abundance is present along the outermost edge (4 0 width regions), while the inner region shows strongly depleted abundances. This structure has been confirmed both by the plasma model fit and by the model-free fit. We noticed that the rim regions showing normal abundance correspond to those with a relatively weak radio intensity. Since the Cygnus Loop is believed to be the result of a cavity explosion, we discuss that the abundance distribution is due to the abundance difference between the cavity wall and its outside. The origin of the depleted abundance still remains an open question.

We observed the northern rim of the Cygnus Loop with the \textit{Suzaku} observatory in 5 pointings (P21-P25). From the spatially resolved analysis, all the spectra are well fitted by the single component of the non-equilibrium ionization plasma model. From the best-fit parameters, we found that the abundances of the heavy elements are significantly lower than the solar values except those at the outermost edge in P21 and P22. The origin of the depleted metal abundances is still unclear while such deficiencies have been reported from many other rim observations of the Loop. To explain these depletion at the rim regions, we considered the several possibilities. The effects of the resonance-line-scattering and the grain condensation lower the values of the abundances. However, these are not sufficient to account for the abundance depletion observed. We found that the abundances at the outermost edge in P21 and P22 are higher than those at the other regions. From the morphological point of view, it is reasonable to consider that this abundance inhomogeneity is derived from the breakout or the thinness of the cavity wall of the Loop., 15 pages, 7 figures, PASJ, Vol.61, No.3

Highly stereoselective intramolecular Diels–Alder (IMDA) reaction of decatrienoates has been achieved by using a more sterically hindered ester group, i.e., t-butoxycarbonyl, or electron-withdrawin...

歴青炭の乾留物を原料とし,二酸化炭素または水で賦活することにより活性炭を得た.原料炭中には,無定形炭素質からなる易燃性部位と,微結晶黒鉛からなる難燃性部位とが細かく入り組んで混在している.賦活反応によって酸化されるのは易燃性部位であり,その燃えた跡がミクロ細孔となる.用いた原料炭の易燃性部位の密度は2.05gcm-3であり,原料炭中に占める割合は45wt%であった.さらに,賦活剤の炭素質表面への吸着を考慮した燃焼速度式を導き,賦活反応の機構を調べた.

X-ray spectroscopic measurements of the Cygnus Loop supernova remnant indicate that metal abundances throughout most of the remnant's rim are depleted to about 0.2 times the solar value. However, recent X-ray studies have revealed in some narrow regions along the outermost rim anomalously "enhanced" abundances (up to about 1 solar). The reason for these anomalous abundances is not understood. Here, we examine X-ray spectra in annular sectors covering nearly the entire rim of the Cygnus Loop using Suzaku (21 pointings) and XMM-Newton (1 pointing). We find that spectra in the "enhanced" abundance regions commonly show a strong emission feature at about 0.7 keV. This feature is likely a complex of He-like O K(gamma + delta + epsilon), although other possibilities cannot be fully excluded. The intensity of this emission relative to He-like O Kalpha appears to be too high to be explained as thermal emission. This fact, as well as the spatial concentration of the anomalous abundances in the outermost rim, leads us to propose an origin from charge-exchange processes between neutrals and H-like O. We show that the presence of charge-exchange emission could lead to the inference of apparently "enhanced" metal abundances using pure thermal emission models. Accounting for charge-exchange emission, the actual abundances could be uniformly low throughout the rim. The overall abundance depletion remains an open question., Comment: Published in ApJ

A 532 nm red pigment formed in the thiobarbituric acid (TBA) assay of human urine was characterized after separation of the pigment by high-performance liquid chromatography. The yield of the red pigment was somewhat higher at pH 2 than at pH 5; its development was not inhibited by ethylenediaminetetraacetic acid. The characteristics of the pigment were similar to those of the pigment derived from standard malonaldehyde. The amount of the pigment formed was roughly equal to the content of malonaldehyde derivatives estimated as 1-(2,4-dinitrophenyl)pyrazole. Pigment formation was significantly enhanced by t-butyl hydroperoxide (t-BuOOH) and ferric ions, which may be due to pigment formed from aldehydes other than malonaldehyde; the presence of these aldehydes was confirmed by the formation of the corresponding 2,4-dinitrophenylhydrazones. The amount of pigment produced from 24-h urine samples of 12 healthy subjects was estimated to be 26-95 nmol/kg, and 65-182 nmol/kg in the presence of t-BuOOH. These values are lower than those for urine of rabbit or rat. The TBA reactivity in the absence and presence of t-BuOOH of human urine was not related to age or sex. The TBA reactivity of human urine collected in the afternoon and in the evening was higher than that of urine collected in the morning.

Detection and quantitative determination of the components : i) radical species, ii) hydroperoxides, iii) secondary aldehydes, hydrocarbons and fatty acids, and iv) reaction products between proteins, which are generated during lipid peroxidation, are reviewed. Determination of plural classes of components is required for the accurate monitoring of lipid peroxidation. Among the many known assay methods, thiobarbituric acid test can be properly used for the monitoring of lipid peroxidation. The principles of the test, which has been recently clarified, is reviewed in detail.

We conducted a comprehensive study on the shell structure of the Cygnus Loop using 41 observation data obtained by the Suzaku and the XMM-Newton satellites. To investigate the detailed plasma structure of the Cygnus Loop, we divided our fields of view into 1042 box regions. From the spectral analysis, the spectra obtained from the limb of the Loop are well fitted by the single-component non-equilibrium ionization plasma model. On the other hand, the spectra obtained from the inner regions are well fitted by the two-component model. As a result, we confirmed that the low-temperature and the high-temperature components originated from the surrounding interstellar matter (ISM) and the ejecta of the Loop, respectively. From the best-fit results, we showed a flux distribution of the ISM component. The distribution clearly shows the limb-brightening structure, and we found out some low-flux regions. Among them, the south blowout region has the lowest flux. We also found other large low-flux regions at slightly west and the northeast from the center. We estimated the former thin shell region to be 1.3 degrees in diameter and concluded that there exists a blowout along the line of sight in addition to the south blowout. We also calculated the emission measure distribution of the ISM component and showed that the Cygnus Loop is far from the result obtained by a simple Sedov evolution model. From the results, we support that the Cygnus Loop originated from a cavity explosion. The emission measure distribution also suggests that the cavity-wall density is higher in the northeast than that in the southwest. These results suggest that the thickness of the cavity wall surrounding the Cygnus Loop is not uniform., 8 pages, 7 figures, accepted for publication in ApJ

Highly stereoselective intramolecular Diels–Alder (IMDA) reaction of decatrienoates has been achieved by using a more sterically hindered ester group, i.e., t-butoxycarbonyl, or electron-withdrawin...

著者人数：29名, Accepted: 2009-07-15, 資料番号: SA1001000000

The thiobarbituric acid (TBA) reactivity of oxidized methyl linoleate, soybean oil, sesame oil, lard, chicken oil and sardine oil was characterized by using four different methods with 0.01% butylated hydroxytoluene (BHT). Optimal pH for the reactivity of most of the oxidized samples was 3–4, and that of some samples was above 5. Introduction of 2 mMt-butyl hydroperoxide (t-Bu00H) or 0.2 mM ferric ion in the reaction markedly enhanced the reactivity. Introduction of 0.2 mM ethylenediamine tetraacetic acid suppressed the reactivity. The characteristics of the TBA-reactivity of the samples were similar to those of alkadienals or alkenals. The most preferable method for the estimation of the TBA-reactive substances of the oxidized fats and oils was that using solvents at pH 3.5 with introduction of BHT, andt-Bu00H or ferric ion.

In the thiobarbituric acid (TBA) assay of oxidized oils, the development of red 2 : 1 TBA-malonaldehyde adduct was enhanced by ferric and ferrous ions and suppressed by EDTA in a dose-dependent manner. The effect of the ions could not be ascribed to the increased release of malonaldehyde from the oils, but was reasonably ascribable to the increased TBA-reactivity of alkadienals and/or alkenals released from the oils, since the reactivity of these aldehydes was quite similarly enhanced by the ions and suppressed by EDTA. The development of the adduct from the oils, alkadienals and alkenals was suppressed by cupric ion, probably owing to its activity to destroy the adduct. These findings strongly support the idea that alkadienals and/or alkenals are the major TBA-reactive substances in the oxidized oils.

The level of urinary thiobarbituric acid (TBA) reactants in healthy human subjects due to malonaldehyde derivatives was measured to assess the lipid peroxidation status of the whole body. For each subject the TBA reactant level over a day varied over a 2-3 fold range while the daily level varied over a 1.5-3 fold range under normal life-style conditions. One of the factors causing an increase in the reactant level within a single day may be the subjects's physical activity, because the reactant level of each subject was higher in the afternoon or in the evening than in the morning. Remaining awake all night or hard exercise caused a dramatic increase in the reactant level over a day and in the daily reactant level. The reactant level within a single day for a subject was increased 5.5 fold and the daily level 3 fold by remaining awake all night, and the level within a day was increased 22 fold by hard exercise while the corresponding daily level was increased 7 fold. It is unlikely that food, alcohol and smoking greatly affect the reactant level. The results suggest that increased physical activity enhances lipid peroxidation in the whole body and thus the increased urinary excretion of malonaldehyde derivatives.

The thiobarbituric acid (TBA) reactivity of rat liver and brain homogenates was characterized to elucidate what kinds of aldehyde species contributed to the reactivity. Characteristic pH dependence of the reactivity with a maximum at around pH 3 and marked enhancement of the reactivity by t-butyl hydroperoxide (t-BuOOH) and ferric ion were similar to those of alkadienals. The amounts of aldehyde species, including alkadienals determined as 2,4-dinitrophenylhydrazones, were high enough to account for the enhanced reactivity. The reactivity was inhibited by ethylenediaminetetraacetic acid (EDTA) but not completely, suggesting the presence of malonaldehyde whose reactivity was not affected by EDTA. The amounts of malonaldehyde determined as 1-(2,4-dinitrophenyl)pyrazole could account for a part of the reactivity in the presence of EDTA. Hence, the TBA reactivity of liver and brain homogenates at around pH 3 in the presence of t-BuOOH and ferric ion may be accounted for by alkadienals and malonaldehyde and that in the presence of EDTA by malonaldehyde.

The fluorometric thiobarbituric acid (TBA) assay of blood plasma was performed under various conditions in order to assess whether the assay reflects lipid peroxidation. The TBA-reactivity of malonaldehyde was not dependent on the pH values of the reaction and was little affected by tert-butyl hydroperoxide (tert-BuOOH). The rectivity of 2, 4-nonadienal and 2-hexenal, which was maximal at pH 3-4 and at above pH 4, respectively, was dramatically enhanced by tert-BuOOH and ferric ion, and suppressed by ethylenediaminetetraacetic acid (EDTA). The pigment formation from oxidized low-density-lipoprotein was maximal at about pH 5, markedly enhanced by ferric ion and suppressed by EDTA, indicating that the TBA-reactive substances in the oxidized lipoprotein were composed of malonaldehyde, alkadienals and alkenals originated from lipid peroxidation. The pigment formation from plasma and its phosphotungstic acid precipitate was maximal at pH 4 and at below pH 2, respectively. The effect of tert-BuOOH, ferric ion and EDTA was not significant. The major TBA-reactive substances from plasma may be compounds other than malonaldehyde, alkadienals, alkenals and those in the oxidized lipoprotein. The TBA-reactivity of plasma does not appear to be specific to lipid peroxidation.

Thiobarbituric acid (TBA) assay of rat liver homogenate was performed by four general variations with 0.01% butylated hydroxytoluene. Development of red pigment was greatly dependent on the methods. The pigment formation by each method was dramatically increased by introduction of 2 mM t-butyl hydroperoxide (t-BuOOH). The pH values of the reaction mixtures greatly affected the pigment yield both in the absence and presence of t-BuOOH, and the maximal pigment yield was obtained at pH 3-4. These characteristic profiles of the pigment formation were similar to those from alkadienals and essentially different from those from malonaldehyde. Alkadienals were likely candidates for the TBA-reactive substances in the homogenate.

A.c. electrical measurements and impedance analysis have been carried out to characterize silica-supported heteropoly compounds (HPC), viz. 12-molybdophosphoric acid (H3PMo12O40), 12-tungstophosphoric acid (H3PW12O40) and their sodium, potassium, and caesium salts under various conditions of humidity. The absorption of water was found to enhance the electrical conductivity of silica-supported HPC. In H3PMo12O40 and its salts supported on silica, complex-impedance plots showed one semicircular arc due to adsorbed water. For H3PW12O40 and its salts supported on silica, the plots showed two arcs; these are ascribed to fast and slow relaxation processes of orientation polarization for conductive species, supposedly protons in occuluded and adsorbed water, respectively. As the relative humidity was increased, the conductivity increased logarithmically, showing humidity-sensing characteristics. The conduction behaviour was affected by the loaded amount of HPC and the substitution of cations in HPC. The activation energy for electrical conduction of low-loaded heteropoly acid (HPA) on silica was lower than that for bulk HPA. It changed both with the amount of loaded HPA and with the substitution for hydrogen ions in the loaded HPA.The acidity function, H0, of the silica-supported HPC has been examined also in connection with their electrical behaviour. The electrical conductivity increased with increasing acidity. A linear relationship was found between the electrical conductivity and the acidity function.

Excavated bones (rib) obtained from 50 sites in Japan were measured by ICP atomic emission spectrometry and atomic absorption spectrometry for concentration of 19 elements, including Al, B, Ca, Cd, Cr, Co, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V and Zn. One hundred and forty-one specimens were classified into five groups according to Japanese prehistoric and historic eras (Jomon, Yayoi, Kofun, Kamakura and Muromachi, and Edo). The elements, with concentrations which showed no significant change with era were Al, B and Cr. Average concentrations of Ca were in the range 2-2.5 X 10(-1) g g-1 and those of P ranged from 1.1 to 1.3 X 10(-1) g g-1, indicating a well-preserved bone mineral matrix. The Ca/P ratio (mol/mol) was lowest in the Edo group--1.48 as compared with 1.54-1.66 in the other groups. Among the elements which showed changes with era were Pb, Fe, Co and Mn, all of which showed remarkably elevated concentrations in the Edo group. In addition to this unique elemental composition of Edo bones, samples from the Kofun era showed a completely different composition from those of other periods, i.e. they had the highest concentrations of Cd, Zn and Mg, and the lowest concentrations of Cu, K, Ni and Sr. The cause of the elevated Pb concentration in Edo bones is discussed in relation to human activities which may have led to environmental Pb pollution.

Thiobarbituric acid (TBA) reaction of several aldehydes and oxidized lipids in glacial acetic acid was performed. All the samples were freely soluble in the solvent used. Saturated aldehydes produced a stable yellow pigment with an absorption maximum at 455 nm, a red pigment derived from malonaldehyde at 532 nm, and an orange pigment due to dienals at 495 nm. The absorbance maximum was 7–9 per μmol for saturated aldehydes, 27.5 per μmol for malonaldehyde and about 2 per μmol for dienals. Autoxidation of unoxidized lipids increased progressively in glacial acetic acid. When the TBA test was performed under nitrogen, autoxidation of unoxidized lipids was inhibited completely. While saturated aldehydes produced no yellow pigment under nitrogen, oxidized lipids produced a considerable amount of stable yellow pigment. The value for absorbance at 455 nm as a function of autoxidation time paralleled those of peroxide values. The absorbance of most oxidized lipids at 455 nm was higher than at 532 nm. Yellow pigment formation in the TBA test under nitrogen could not be ascribed to free saturated aldehydes but rather to unspecified closely related substances. The stable yellow pigment was found to be an excellent indicator of lipid oxidation.

Double-headed aspirin [bis(3,5-dibromosalicyl)fumarate] selectively cross-links hemoglobin molecules between Lys 82 beta 1 and Lys 82 beta 2 and increases solubility of deoxy-Hb S (Walder et al., J. Mol. Biol., 141:195, 1980 and Kikugawa et al., J. Biol. Chem., 257:7525, 1982). We reacted this reagent with the mixture of Hb A and Hb S and the mixture of Hb S and Hb York (beta 146His replaced by Pro). Cross-linked asymmetrical hybrid hemoglobins (alpha 2 beta - beta S and alpha 2 beta Y - beta S) were produced in high yields in addition to the cross-linked parent hemoglobin molecules. Results on electrophoresis, gel electrofocusing, ion exchange column chromatography, mechanical stability and oxygen binding properties showed that the cross-linked asymmetrical hybrid hemoglobins had properties intermediate between those of the cross-linked parent hemoglobins. Oxygen affinities of the cross-linked asymmetrical hybrids were not affected by the addition of 2,3-diphosphoglycerate (DPG) or inositol hexaphosphate, probably due to the presence of a fumaryl group at the DPG binding site.

Fingernail specimens were taken from 339 Japanese subjects assigned to one of six age groups. Red chromogen was obtained by the reaction of nail samples with a 66% aqueous solution of sulfuric acid in a boiling water bath. Although the structure of the red chromogen was unidentified, the content of chromogen was found to be correlated with the age of the subject. The values for the concentration were remarkably high in newborns, infants and children (group I), but decreased gradually by the age of 10(group II). There was no appreciable difference between values in adults.

Nineteen elements (Al, B, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Sr, Ti, V and Zn) were analyzed in excavated bone (rib) of the Edo era (a Japanese historical era, 300-120 BP (before present)) from different burial conditions in Tokyo, and in contemporary Japanese bone (rib) obtained from autopsy cases. The elemental composition of the excavated bones varied according to their burial conditions. The concentration of soil-related elements such as Fe, Mn, Co and Ti in the bone was lowest in the samples in the “wooden coffin in a stone room”, next lowest in the “funeral urn with mud”, and highest in the “wooden coffin full of mud”. The Pb concentration was higher in excavated bones than in contemporary bones and much higher, by as much as several tens μg/g, in the bones in the “wooden coffin in a stone room” and in the “funeral urn with mud”. These results stongly support the notion that Japanese in the city of Edo were highly polluted by environmental lead.

A second case of Hb York (beta 146 His leads to Pro), was discovered in a patient with polycythemia. The oxygen equilibrium curves (OEC) of red cell suspensions in a buffer (pH 7.4) at 37 degrees C revealed a biphasic curve with a P50 of only 12.5 mm Hg (normal value: 26.5 +/- 1.0 mm Hg). The purified Hb York had an extremely high affinity for oxygen with diminished cooperativity and decreased Bohr effect. The oxygen affinity was significantly reduced by inositol hexaphosphate. Molecular stability studies by mechanical shaking of various liganded forms of Hb York revealed stabilities between those of Hb A and Hb S. Isolated beta Y-subunits were more unstable than beta A-subunits at every pH examined. Hb York was 1.4 times more unstable than Hb A in 18.9% isopropanol.

A mixture of malonaldehyde, an alkenal, an alkadienal and an organic hydroperoxide, as an oxidized lipid model, was made to react with thiobarbituric acid (TBA) in 4% acetic acid at 100°C for 20min. Amount of a red pigment, formed from the alkenal and the alkadienal, was greatly increased with the amounts of other components. A combination of that alkenal and alkadienal or that of two alkadienals synergistically enhanced the pigment formation. Organic hydroperoxides dramatically enhanced this formation from these aldehydes. Intermediary 1:1 adducts of the aldehydes with TBA were effectively converted to the pigment in the presence of hydroperoxides. Pigment yield was much greater than that of the malonaldehyde content in the mixture. Alkenals, alkadienals and hydroperoxides may contribute to formation of red pigment synergistically in TBA tests for oxidized lipids.

The reaction of thiobarbituric acid (TBA) with saturated aldehydes, i.e., 1-butanal, 1-hexanal and 1-heptanal, produced a 455-nm yellow and a 532-nm red pigment. Formation of the pigments depended on the reaction conditions. The yellow pigment was unstable in the presence of excess amounts of the saturated aldehydes. The red pigment was formed only when the reaction was performed at a TBA/aldehyde ratio of 1:1 in aqueous acetic acid. Formation of the yellow and red pigments required molecular oxygen. The colorless adducts, intermediates for the yellow and the red pigments, were isolated from the reaction mixtures. Aldol condensation and dehydration of 2 mol of the saturated aldehydes initially gave the alpha, beta-unsaturated aldehydes, which in turn reacted with TBA to form the colorless adducts, pyranopyrimidine derivatives. The adducts were then converted into the yellow and red pigments under aerobic conditions.

Various porous glasses were prepared by the extraction with HCI of borosilicate glasses (NazO 5 B20s, 12.7rSiO2), tchich was vafiotisly phase-separated by c6ntrolling the temperature and period of heat treatment. lsotherms of benzene sorption at OeC on the porous glass changed regularly in shape depending on the conditions of the pretreatment (Figs.1, 2, 3 and 4). Table 1 lists extracted fraction f (g!g) Qf each specimen, together with sorption characteristics obtained from BET plots and the isotherins. Analogous data from me. tnth. anol isotherms are given in Table 2. These results were discussed on the basis of capillary condensation theory. The shape of the benzene isotherm are different from that of methanol in some cases (Figs.5, 6), but pore distribution curves calculated from them agreed with each other except small difference in the very low pressure region. Figs.7 and 8 show that the theoretical condensation isotherms for the assembly of fine spheres arranged in the closest packing are in fair agreement with the experim. ental isotherms, when the granules of Jsepar-ate-d. pba-se a-r. e grgwn"up syfficignt, Ly. (ca: 5. ---t600 A in diameter). Volume of pore space ge calculated by f/2.20(1-f) is given in Fig.9by solid line and also in the last cQlumn of Table 1. Experimental values s asL, btained from the saturated amount of sorption as, are in agreement with thsO witl in 10%e of error for pecimens in which granules have grewn up sufficiently. Large deviations in Fig.9 are found with the specimens giving the type (1) isotherm and might be attributed to very fine pores possessing molecular-sieve effect for methanol as well as for benzene molecules. Thus, on the basis of capillary eoRdensation theory, it is concluded that regular change in isotherms is due te the growth of granules originated from silica-rich phase, and the pore space effective for sorption is formed by dissolution of the intergranular

The thiobarbituric acid (TBA) reaction was performed on linoleic acid 13-monohydroperoxide, autoxidized fatty esters, edible fats and oils, rat liver microsomal lipids, and on human erythrocyte ghost lipids in order to determine which substances from peroxidized lipids are TBA-reactive. The reaction was carried out in 2% acetic acid containing butylated hydroxytoluene using two different reaction modes: a one-step mode which involves heating at 100°C, and a two-step mode which involves first treatment at 5°C and subsequent heating at 100°C. Yields of the red 1∶2 malonaldehyde/TBA adduct, as estimated by absorbance, fluorescence intensity and high-performance liquid chromatography, were much higher than the malonaldehyde content as determined by direct chemical analysis. Yields of red pigment obtained by the two-step mode were slightly higher than those obtained by the one-step mode. Pigment yields were dramatically increased by addition oft-butyl hydroperoxide. Red pigment formation from alkenals and alkadienals was similarly enhanced by the two-step mode or by addition oft-butyl hydroperoxide, whereas pigment formation from malonaldehyde was not. It appears likely that a component of the total red pigment formed from the peroxidized lipids was due to aldehyde species other than malonaldehyde.

This paper describes what components produce a red pigment in the thiobarbituric acid (TBA) test of peroxidized lipids. Alk-2-enals, alka-2,4-dienals and hydroperoxide functions are potential candidates for the red pigment in the TBA test. The TBA test can be regarded as an excellent method to reflect the combined effect of these components and thus the degree of lipid oxidation.

Malondialdehyde (MDA) was found to react with normal hemoglobin A (Hb A), forming a number of less cationic components which were detected by cellulose acetate electrophoresis and gel electrofocusing. All the modified components moved down the cation-exchange resin at a quicker rate than Hb A, and this chromatographic behavior of the modified components was similar to that of glycosylated Hb A. Some of these modified components were intermolecularly crosslinked, and showed fluorescence with an excitation maximum at 390 nm and an emission maximum at 460 nm. It is likely that MDA reacts nonspecifically with the epsilon-amino groups of lysine and N-terminal amino groups to produce aminoacrolein, crosslinks, and strongly fluorescent 1,4-dihydropyridine-3,5-dicarbaldehyde. Oxygen affinity of the modified hemoglobins was increased. The modified hemoglobins were more readily oxidized into met-form. Mechanical stability of Hb A was also decreased by the modification. These results suggest that a considerable conformational change in Hb A was induced by the treatment with MDA. Since MDA is generated in erythrocytes as a consequence of liquid peroxidation, MDA may react with intracellular Hb A and influence the function and the stability of hemoglobin.

The reaction of four to eight carbon straight-chain alk-2-enals with 2-thiobarbituric acid (TBA) produced yellow 455-nm-, orange 495-nm-, and red 532-nm-absorbing pigments depending upon the reaction conditions. The 1:1 reaction of the aldehydes with TBA in 15% acetic acid at 100 degrees C produced the yellow pigment at 0.25 h and the red at 6 h. The reaction of the aldehydes with TBA in excess at 100 degrees C produced the yellow at 0.25 h, the orange at 2-6 h, and the red at 0.25-6 h. The formation of these pigments required molecular oxygen. These pigments could be separated from each other on HPLC. The red pigment formed from the aldehydes could not be distinguished from the red 1:2 malonaldehyde-TBA adduct by absorption spectrum and HPLC. The red color yield was the highest in the 1:1 reaction and retarded in the reaction with TBA in excess. The red color due to these aldehydes may contribute in part to the color formed in the general TBA test of lipid oxidation. The 1:1 reaction initially produced colorless 1:1 adducts X, which were subsequently converted into the yellow and red pigments under aerobic conditions. The reaction of the aldehydes with TBA in excess might initially produce X and then another colorless 1:2 adducts Y; the latter being converted into yellow, orange, and red pigments under aerobic conditions.

When autoxidized chicken fat and unsaturated fatty acids were subjected to thiobarbituric acid (TBA) test in trichloracetic acid, all samples revealed two absorption maxima at 532 and 455 nm. Rate of increase in the TBA-reactive substances (TBARS) at 532 nm was different from that in the TBARS at 455 nm. It was suggested that there were several kinds of TBARS in the autoxidized samples: the TBARS at 532 mn which were unstable in the autoxidation process and slowly liberated malonaldehyde; the TBARS at 532 nm which liberated malonaldehyde rapidly; and the TBARS at 455 nm which liberated other aldehydes unstable after reaction with TBA.