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T Inubushi

Publications and source records attributed to T Inubushi.

At least 109 records · Page 6Linked to original sources
PubMed1991

Observation of rat hind limb skeletal muscle during arterial occlusion and reperfusion by 31P MRS and 1H MRI.

31P NMR spectra and 1H MR T1- and T2-weighted spin-echo images were concurrently observed in rat hind limb during arterial occlusion and following reperfusion. With arterial occlusion, phosphocreatine level decreased and inorganic phosphate (Pi) level increased in 31P NMR spectra. Intracellular pH's dropped as a function of time. Beta-ATP started to decrease in three hours. In six hours after the occlusion, any peaks other than Pi were scarcely detected. The signal intensities in the 1H MR images increased homogeneously in both T1- and T2-weighted conditions, but the changes were more profound with T2-weighted images. After the release of the arterial occlusion, the 31P NMR spectra recovered to the preischemic state in several hours. The 1H MR images during reperfusion showed characteristic heterogenous pattern. The signal intensities in the anterior tibial muscle and the gastrocnemius muscle remained high in T1-weighted condition and the intensities further increased in T2-weighted condition, while those in other parts returned to the preischemic level. These changes were found to be irreversible even 12 hr after the release. The high signal intensities suggested the increase of water in the extracellular compartment induced by so-called reperfusion injury. Multinuclear analysis using in vivo NMR was valuable to consecutively detect time-dependent and location-specific response in skeletal muscle during ischemia and reperfusion.

Adenosine Triphosphate↗
PubMed1991

The mechanism underlying heterogeneous pH in ischemic and reperfused myocardium.

The mechanism responsible for heterogeneity in tissue pH was investigated in perfused rat hearts subjected to ischemia/reperfusion insult, by correlating the time course of pH changes to the severity of vascular impairment. In 25 perfused hearts, myocardial pH was monitored by 31 P-NMR spectra. During ischemia, pH, which was 7.1 at the beginning of ischemia, progressively decreased and reached a steady level of 5.9 (5.9-compartment) after 40 minutes. In addition, another define peak of pH 7.1 (7.1-compartment) became evident after 50 min of ischemia. The 7.1-compartment grew higher with ischemic time and was only observed after 180 min of ischemia. Although reperfusion after 20 min of ischemia recovered pH, ATP, and creatine phosphate, reperfusion after 50 min left two Pi peaks, the 5.9- and 7.1-compartments; the former gradually decreased with a concomitant increase of the latter. Reperfusion after 180 min of ischemia with various pH levels did not shift the Pi peak from pH 7.1, suggesting that the perfusate did not reach that compartment, the impaired flow region. High coronary resistance and a heterogeneous staining pattern concomitant with a late appearance of the 7.1 component further supported this hypothesis. Myocardial coenzyme Q10 radical, an indicator of the tissue redox state, was also low in those hearts which were reperfused after 50 min of ischemia. Thus, the splitting of the Pi peak, caused by reperfusion after prolonged ischemia, represents the existence of a no-reflow region.

Animals↗
PubMed1990

[Association of indoor air pollution and passive smoking with lung cancer in Osaka, Japan].

A hospital-based case-control study was conducted at 8 hospitals in Osaka in order to clarify risk factors among non-smoking women. A total of 129 lung cancer cases and 519 controls were investigated. An elevated risk was observed for women who had used wood or straw as cooking fuels at 30 years of age. Maternal smoking in childhood also seemed to raise the risk. No elevated risks were observed for husband smoking and use of heating apparatus so far.

Air Pollution↗
PubMed1989

Study of the 5-oxoprolinase reaction by 13C NMR.

5-Oxoprolinase catalyzes the ATP-dependent decyclization of 5-oxo-L-proline to L-glutamate. Previous studies provided evidence for the intermediate formation of a phosphorylated form of 5-oxoproline (Seddon, A. P., and Meister, A. (1986) J. Biol. Chem. 261, 11538-11541) and of a tetrahedral intermediate (Li, L., Seddon, A. P., and Meister, A. (1987) J. Biol. Chem. 262, 11020-11025). A new approach to the study of the reaction mechanism using the 18O isotope effect on the 13C NMR signals for 5-oxoproline and glutamate is reported here. The 13C chemical shifts induced by 18O substitution for the carbonyl group of 5-oxoproline and the gamma-carboxyl group of glutamate are about 0.03 ppm with respect to the corresponding 16O-compounds. Using 5-[18O]oxo[5-13C]proline (97 and 79.5 atom % excess, 13C and 18O, respectively), the disappearance of the 18O-labeled and unlabeled 5-oxoproline and formation of the corresponding glutamate species were followed in the reactions catalyzed by purified preparations of 5-oxoprolinase isolated from Pseudomonas putida and from rat kidney. This procedure permits simultaneous determinations of the rates of 18O exchange and of the overall decyclization reaction. The ratios of 18O exchange rates to the overall reaction rates for the bacterial and kidney enzyme catalyzed-reactions were 0.28 and 0.14, respectively. The findings support the view that the coupling of ATP hydrolysis to 5-oxoproline decyclization involves formation of a phosphorylated tetrahedal intermediate. Although the exchange phenomena are consistent with the mechanistic interpretations, they seem not to be required for catalysis.

Adenosine Diphosphate↗
PubMed1989

Partial purification of inositol polyphosphate 1-phosphomonoesterase with characterization of its substrates and products by nuclear magnetic resonance spectroscopy.

A study of the enzyme activities that degrade Ins(1,3,4)P3 in rat brain showed that it was dephosphorylated primarily by a Mg2+-dependent inositol polyphosphate 1-phosphomonoesterase to Ins(3,4)P2 and then to Ins(3)P by a 4-phosphomonoesterase. A less active enzyme activity with the properties of a 4-phosphomonoesterase that converted Ins(1,3,4)P3 to Ins(1,3)P2 was also detected. The inositol polyphosphate 1-phosphomonoesterase was separated from the 4-phosphomonoesterase and the inositol monophosphate phosphomonoesterase by chromatography on phosphocellulose, DE-52 anion exchange and hydroxylapatite columns. Kinetic characterization of the partially purified inositol polyphosphate 1-phosphomonoesterase indicated that both Ins(1,3,4)P3 and Ins(1,4)P2 were substrates with apparent Km values of 0.9 microM and 0.7 microM, respectively. Either substrate was a competitive inhibitor of the other substrate and dephosphorylation of both substrates was directly inhibited by Li+ in an uncompetitive manner. These data strongly suggest that a single enzyme dephosphorylates both Ins(1,3,4)P3 and Ins(1,4)P2. The 4-phosphomonoesterase that dephosphorylated Ins(3,4)P2 to Ins(3)P was insensitive to Mg2+ and Li+ and was probably the same enzyme that degraded Ins(1,3,4)P3 to Ins(1,3)P2. The isomeric configurations of the major inositol polyphosphates formed from the degradation of Ins(1,3,4,5)P4 were determined using 1H- and 31P-NMR spectroscopy, and confirmation of the structures assigned to Ins(1,3,4,5)P4, Ins(1,3,4)P3 and Ins(3,4)P2 was obtained.

Animals↗
PubMed1988

Proton nuclear magnetic resonance study of the ferrous derivatives of the dimeric and tetrameric hemoglobin from the mollusc Scapharca inaequivalvis.

Proton NMR spectra have been measured for the two hemoglobins from the mollusc Scapharca inaequivalvis: HbI, a homodimer, and HbII, a heterotetramer. These hemoglobins are endowed with a unique subunit assembly, since the heme carrying E and F helices are involved in the major intersubunit contact. In the far-downfield region of hyperfine-shifted resonances the spectra of HbI and HbII in the deoxy state show respectively one (66.7 ppm) and two (67.8 and 63.6 ppm) exchangeable signals of the proximal histidine N delta H groups, the resonance position being indicative of a significant strain in the iron-imidazole interaction. In the hydrogen-bonded proton region, inter- and intrasubunit hydrogen-bonded proton signals have been detected for both hemoglobins. Deoxy-HbI shows two unique downfield resonances at 11.83 and 11.51 ppm which disappear in the oxygenated state, suggesting that the corresponding hydrogen bonds are involved in the stabilization of the tertiary and/or quaternary structure of the deoxy form. HbII shows even smaller changes in this region upon changes in ligation state. These results therefore provide further proof that, at variance with the vertebrate hemoglobin tetramer, the unique subunit assembly of these proteins is stabilized mainly by hydrophobic interactions.

Animals↗
PubMed1988

Assessment of proton nuclear magnetic resonance spectroscopy for detection of malignancy.

Water-suppressed proton nuclear magnetic resonance spectra were generated (by using 360 and 500 MHz systems) from human plasma and serum samples taken from 35 apparently healthy individuals, 52 patients with overt malignancies, and 37 patients with hypertriglyceridemia (triglycerides greater than 200 mg/dL or 2.26 mmol/L). The line widths from the lipoprotein-lipid methylene and methyl resonances at approximately 1.3 and 0.9 ppm were averaged by the method of Fossel et al. (N Engl J Med 1986;315:1369-76), but, contrary to their findings, we were unable to distinguish normal individuals from those with malignant tumors (e.g., mean +/- SD line width at 360 MHz: normal group = 32.9 +/- 3.6 Hz, malignant group = 28.3 +/- 4.9 Hz). The average line-width measurements (y), however, varied with the triglyceride content (x, mg/dL) of the plasma or serum as follows (logarithmic transformation of the data determined at 360 MHz and regression analysis): y = 110 (x-0.27). Data from both nonmalignant and malignant specimens fit this equation, the coefficient of correlation being -0.91. These findings suggest that considerable caution should be used in interpreting water-suppressed proton NMR spectra for cancer detection.

Adult↗
PubMed1987

Proton nuclear magnetic resonance and spectrophotometric studies of nickel(II)-iron(II) hybrid hemoglobins.

Ni(II)-Fe(II) hybrid hemoglobins, alpha(Fe)2 beta(Ni)2 and alpha(Ni)2 beta(Fe)2 have been characterized by proton nuclear magnetic resonance with Ni(II) protoporphyrin IX (Ni-PP) incorporated in apoprotein, which serves as a permanent deoxyheme. alpha(Fe)2 beta(Ni)2, alpha(Ni)2 beta(Fe)2, and NiHb commonly show exchangeable proton resonances at 11 and 14 ppm, due to hydrogen-bonded protons in a deoxy-like structure. Upon binding of carbon monoxide (CO) to alpha(Fe)2 beta(Ni)2, these resonances disappear at pH 6.5 to pH 8.5. On the other hand, the complementary hybrid alpha(Ni)2 beta(Fe-CO)2 showed the 11 and 14 ppm resonances at low pH. Upon raising pH, the intensities of both resonances are reduced, although these changes are not synchronized. Electronic absorption spectra and hyperfine-shifted proton resonances indicate that the ligation of CO in the beta(Fe) subunits induced changes in the coordination and spin states of Ni-PP in the alpha subunits. In a deoxy-like structure, the coordination of Ni-PP in the alpha subunits is predominantly in a low-spin (S = 0) four-coordination state, whereas in an oxy-like structure the contribution of a high-spin (S = 1) five-coordination state markedly increased. Ni-PP in the beta subunits always takes a high-spin five-coordination state regardless of solution conditions and the state of ligation in the partner alpha(Fe) subunits. In the beta(Ni) subunits, a significant downfield shift of the proximal histidyl N delta H resonance and a change in the absorption spectrum of Ni-PP were detected, upon changing the quaternary structure of the hybrid.(ABSTRACT TRUNCATED AT 250 WORDS)

Binding Sites↗
PubMed1987

Proton magnetic resonance of the bovine spleen green heme-protein.

The ferric spleen green heme-protein exhibits hyperfine-shifted proton resonances between 90 and 20 ppm for the high-spin resting form and the chloride complex, and between 46 and -9.4 ppm for the low-spin nitrite complex. The proton NMR spectral profile of the enzyme is similar to that of lactoperoxidase, but different from those of common heme-proteins. The appearance of a resonance at 76 ppm in the ferrous enzyme shows the presence of a proximal histidine residue linked to the iron. The proton relaxation rates of bulk water indicate that chloride binds to the sixth position of the iron in the chloride complex of the enzyme.

Animals↗
PubMed1987

1H- and 31P-NMR studies on smooth muscle of bullfrog stomach.

31P-NMR spectra of bullfrog stomach smooth muscle showed peaks for creatine phosphate (4.8 mumol X g-1 wet wt.), ATP (3.6), inorganic phosphate (Pi, 2.4), phosphomonoesters (3.0) and phosphodiesters (3.3). The intracellular pH was 7.3, and calculated from the chemical shift of Pi. 1H-NMR spectra of smooth muscle yielded peaks of 2.9 for lactate, 6.6 for total creatine (creatine phosphate + creatine) and methyl protons of choline tentatively assigned to glycerolphosphorylcholine or to membrane phospholipids. Creatine phosphate and ATP decreased under anaerobic conditions, and intracellular acidification was observed with the concomitant increase in lactate. 31P saturation transfer studies showed that saturation of the gamma-ATP resonance reduced the intensity of creatine phosphate to 60% of its control value, and the measured T1 value of creatine phosphate was 2.4 s with saturation. The calculated forward flux of the creatine kinase reaction (decomposition direction of creatine phosphate) was 0.77 mumol X g-1 wet wt. X s-1. The creatine kinase flux was approx. 100-times larger than the ATP turnover rate, calculated from the oxygen consumption rate with the assumption, P/O = 3. In conclusion, the creatine kinase reaction is at equilibrium in resting smooth muscle of bullfrog stomach.

Adenosine Triphosphate↗
PubMed1986

Nuclear magnetic resonance spectroscopic analysis of myo-inositol phosphates including inositol 1,3,4,5-tetrakisphosphate.

1H and 31P NMR spectra of a variety of phosphorylated myo-inositols have been analyzed using a Bruker WH-360 spectrometer. Proton and phosphorus chemical shifts and coupling constants are reported for myo-inositol 1-phosphate, myo-inositol 2-phosphate, myo-inositol 5-phosphate, myo-inositol 1,2-cyclic phosphate, myo-inositol 1,4-bisphosphate, myo-inositol 1,4,5-trisphosphate, and myo-inositol 1,3,4,5-tetrakisphosphate. These data provide the basis for the chemical identification and characterization of biologically relevant inositol phosphates.

Hydrogen↗
PubMed1986

Resonance Raman study on cytochrome c peroxidase and its intermediate. Presence of the Fe(IV) = O bond in compound ES and heme-linked ionization.

Resonance Raman spectra of ferrous and ferric cytochrome c peroxidase and Compound ES and their pH dependences were investigated in resonance with Soret band. The Fe(IV) = O stretching Raman line of Compound ES was assigned to a broad band around 767 cm-1, which was shifted to 727 cm-1 upon 18O substitution. The 18O-isotopic frequency shift was recognized for Compound ES derived in H218O, but not in H216O. This clearly indicated occurrence of an oxygen exchange between the Fe(IV) = O heme and bulk water. The Fe(IV) = O stretching Raman band was definitely more intense and of higher frequency in D2O than in H2O as in Compound II of horseradish peroxidase, but in contrast with this its frequency was unaltered between pH 4 and 11. The Fe(II)-histidine stretching Raman line was assigned on the basis of the frequency shift observed for 54Fe isotopic substitution. From the intensity analysis of this band, the pKa of the heme-linked ionization of ferrocytochrome c peroxidase was determined to be 7.3. The Raman spectrum of ferricytochrome c peroxidase strongly suggested that the heme is placed under an equilibrium between the 5- and 6-coordinate high-spin structures. At neutral pH it is biased to the 5-coordinate structure, but at the acidic side of the transition of pKa = 5.5 the 6-coordinate heme becomes dominant. F- was bound to the heme iron at pH 6, but Cl- was bound only at acidic pH. Acidification by HNO3, H2SO4, CH3COOH, HBr, or HI resulted in somewhat different populations of the 5- and 6-coordinate forms when they were compared at pH 4.3. Accordingly, it is inferred that a water molecule which is suggested to occupy the sixth coordination position of the heme iron is not coordinated to the heme iron at pH 6 but that protonation of the pKa = 5.5 residue induces an appreciable structural change, allowing the coordination of the water molecule to the heme iron.

Computers↗
PubMed1984

High-field, variable-temperature Mössbauer effect measurements on oxyhemeproteins.

We measured Mössbauer spectra of human oxyhemoglobin, its isolated beta chains, and of oxymyoglobin from horse and sperm whale in fields of 4 or 6 T between 4.2 and 200 K in order to characterize the electronic state of the oxyheme complex. Diamagnetic sodium nitroprusside measured under the same conditions served as a control. The spectra of all compounds are reproduced adequately by a model that assumes a diagmagnetic iron and treats the quadrupole splitting, the asymmetry parameter and the Mössbauer linewidth as adjustable parameters. The results provide no indication in the oxyhemeproteins of the excited triplet state that was postulated by Cerdonio and co-workers (Cerdonio, M., Congiu-Castellano, A., Mogno, F., Pispisa, B., Romani, G.L. and Vitale, S. (1977) Proc. Natl. Acad. Sci. USA 74, 398-400) on the basis of susceptibility measurements on oxyhemoglobin.

Humans↗
PubMed1983

Isotropically shifted NMR resonances for the proximal histidyl imidazole NH protons in cobalt hemoglobin and iron-cobalt hybrid hemoglobins. Binding of the proximal histidine toward porphyrin metal ion in the intermediate state of cooperative ligand binding.

Exchangeable imidazole NH proton nuclear magnetic resonance (NMR) signals of the proximal histidine F8, which is directly coordinated to the paramagnetic porphyrin cobalt ion, have been measured for cobalt-substituted deoxyhemoglobins (deoxy-CoHb) and iron-cobalt hybrid hemoglobins, alpha (Co)2 beta (Fe)2 and alpha (Fe)2 beta (Co)2. Comparison of NMR spectra between these Co-substituted hemoglobins and natural Fe-containing hemoglobin allows the assignment of the NH signals to the specific subunits, namely, a signal at 53.8 ppm to the alpha-subunits and a signal at 58.4 ppm to the beta-subunits for deoxy-CoHb at 23 degrees C, respectively. The coordination of carbon monoxide to the beta-subunits in alpha (Co)2- beta (Fe)2 gave rise to an 8 ppm downfield shift of the proximal histidyl NH signal in the deoxy alpha (Co)2 subunits. In contrast, the coordination of carbon monoxide to the alpha-subunits in alpha (Fe)2 beta (Co)2 showed only a 1 ppm downfield shift for the deoxy beta (Co)2 subunits. These observations suggest that the metal-histidyl coordination bonds in the deoxy cobalt subunits are strengthened by the ligation of carbon monoxide in the counterpart ferrous subunits. However, the change of the coordination was much larger in the alpha (Co)2 subunits than that in the beta (Co)2 subunits. Line-width analysis of the NH signals for CO-bound hybrid hemoglobins gave a mean exchange lifetime of 3.2 X 10(3) S-1 for the T to R quaternary structural transition. The proximal histidyl binding situation at some liganded states is discussed in relation to the quaternary structure of hemoglobin molecules.

Chemical Phenomena↗
PubMed1983

Electron paramagnetic resonance studies on cobalt hemoglobin, iron-cobalt hybrid hemoglobins, and their related model complexes. Characterization of proximal histidine binding to porphyrin cobalt(II) ion and its transition associated with subunit interaction.

Electron paramagnetic resonance studies have been conducted on iron-cobalt hybrid deoxyhemoglobins and cobalt deoxyhemoglobin. Examination of alpha (Co)2 beta (Fe)2 hybrid hemoglobin at two different microwave frequencies revealed two sets of axial-symmetric electron paramagnetic resonance (EPR) signals rather than the anisotropic splitting of the g signal as reported previously [Ikeda-Saito, M., Yamamoto, H., & Yonetani, T. (1977) J. Biol. Chem. 252, 8639-8644]. One of these two sets is a characteristically broad spectrum with g = 2.38 and g parallel = 2.03; the other, a sharp spectrum with g = 2.33 and g parallel = 2.03. The alpha-subunits of deoxy-CoHb also exhibited a complex spectrum with a mixture of these two different types of signals. The relative compositions of these two signals were calculated for deoxy-alpha (Co)2 beta (Fe)2 and the alpha-subunits of CoHb, which were profoundly sensitive to the pH of the medium and also to the presence of allosteric effectors. A positive correlation was noticed between the spectral characteristics and the equilibrium extent of oxygenation, showing that the broad component may be associated with the electronic state of the porphyrin metal ion in T-state hemoglobin and the sharp component with that in the R state. In contrast, the complementary hybrid alpha (Fe)2 beta (Co)2 and the beta-subunits in CoHb showed relatively narrow spectra under similar conditions, and only small changes were noted with variation of pH and addition of inositol hexaphosphate. These spectra were close to the sharp component of the alpha-subunits associated with the R state. Comparison of the hemoglobin EPR spectra with those of model cobaltous porphyrin complexes revealed that the restraint that is operative at the fifth ligand position of the prosthetic group in the T state is released in the R state. These ligand binding properties were discussed in relation to the regulation of oxygen binding to hemoglobin.

Cobalt↗
PubMed1983

Co2+ and Mn2+ uptake by crab nerve fibers in resting state and potassium depolarization.

Transition metal ions, Mn2+ and Co2+, are incorporated into nerve fibers when they are applied externally. For nerve fibers in the resting state, however, extracellular and intracellular water may be distinguished by applying transition metal ions externally. NMR spectra of water protons from nerve fibers in high potassium media, which contain transition metal ions, consist of three or more components, reflecting a complex distribution of these ions around the nerve membranes. In the case of Co2+, three components may be identified.

Animals↗