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Biomedical subjects

T Kitagawa

Publications and source records attributed to T Kitagawa.

At least 523 records · Page 29Linked to original sources
PubMed1986

Properties of chemically modified Ni(II)-Fe(II) hybrid hemoglobins. Ni(II) protoporphyrin IX as a model for a permanent deoxy-heme.

Chemical modifications, NES-Cys(beta 93), des-Arg(alpha 141), and both modifications on the same molecule, were made to Ni-Fe hybrid hemoglobins, and their effect on individual subunits was investigated by measuring oxygen equilibrium curves, the Fe(II)-N epsilon (His F8) stretching Raman lines, and light-absorption spectra. The oxygen equilibrium properties indicated that modified Ni-Fe hybrid hemoglobins remain good models for the corresponding deoxy ferrous hemoglobins, although K1, the dissociation equilibrium constant for the first oxygen to bind to hemoglobin, was decreased by the chemical modifications. Resonance Raman spectra of deoxy alpha 2 (Fe) beta 2 (Ni) and light-absorption spectra of deoxy alpha 2 (Ni) beta 2 (Fe), revealed that the state of alpha hemes in both hybrid hemoglobins underwent a transition from a deoxy-like state to an oxy-like state caused by these chemical modifications when K1 was about 3 mm Hg (1 mm Hg approximately 133.3 Pa). On the other hand, the state of beta hemes in hybrid hemoglobins was little affected, when K1 was larger than 1 mm Hg. Modified alpha 2 (Fe) beta 2 (Ni) gave a Hill coefficient greater than unity with a maximum of 1.4 when K1 was about 4 mm Hg. The two-state model predicts that the K1 value at the maximum Hill coefficient should be much larger than this value. For oxygen binding to unmodified alpha 2 (Ni) beta 2 (Fe), oxygen equilibrium data suggested no structural change, while the spectral data showed a structural change around Ni(II) protoporphyrin IX in the alpha subunits. A similar situation was encountered with modified alpha 2 (Ni) beta 2 (Fe), although K1 was decreased as a result of the structural changes induced by the modifications.

Ferrous Compounds↗
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↗
PubMed1986

Control of membrane permeability by external ATP in mammalian cells: isolation of an ATP-resistant variant from Chinese hamster ovary cells.

External ATP causes a great increase in the passive permeability of the plasma membrane for phosphorylated metabolites and other small molecules in cultured mammalian cells. We previously demonstrated that in CHO-K1 cells an ATP-dependent permeability change was induced in the presence of a mitochondrial inhibitor (KCN or rotenone), a cytoskeleton-attacking agent (vinblastine) and a calmodulin antagonist (trifluoperazine). These permeability changes were reversible but long exposure, for 30-60 min, to ATP together with a mitochondrial inhibitor significantly reduced the cell viability of the treated cells. Since this cell lysis was shown to be due to the ATP-dependent permeability change, we could isolate several clones resistant to the action of the external ATP from CHO-K1 cells after repeated treatment with ATP and rotenone. In 9.1 cells, one of the isolated clones, little or no ATP-dependent permeability change was observed in the presence of either a mitochondrial inhibitor, vinblastine or trifluoperazine. This CHO variant could be specifically resistant as to the change in membrane permeability induced by external ATP, since the permeabilities for the 2-deoxyglucose and drugs used in the present studies were similar to those in the case of the parent cells. These results suggest that a specific defect or alteration in the plasma membrane is involved in the ATP-dependent permeability change. It is also reported that Mg2+-dependent ATPase activity was found on the cell surface of both CHO-K1 and 9.1 cells, and this activity was shown to be not involved in the permeability change controlled by external ATP.

Adenosine Triphosphate↗
PubMed1986

Iron-histidine stretching Raman line and enzymic activities of bovine and bacterial cytochrome c oxidases.

Resonance Raman spectra of the reduced form of cytochrome c oxidase isolated from bovine heart and the thermophilic bacterium PS3 were investigated in relation to their H+-pumping- and cytochrome-c-oxidizing activities, which were varied by incubating the enzyme at raised temperatures or at alkaline pH at room temperature. For both the bovine and PS3 enzymes, the intensity of the iron-histidine stretching Raman line of the ferrous a3 heme (214 cm-1) exhibited an incubation-temperature-dependent change, which fell between the similar curves of the H+-pumping and cytochrome-c-oxidizing activities. The intensities of the formyl CH=O stretching Raman line of the ferrous a3 heme (1665 cm-1) as well as of other lines were insensitive to the heat treatment. The iron-histidine stretching Raman line of both enzymes showed pH-dependent intensity change which was nearly parallel with the pH dependence of cytochrome-c-oxidizing activity. Therefore, deprotonation affecting the 214 cm-1 Raman line is responsible for the decrease of activity. This limited alkaline treatment to the PS3 enzyme was reversible and the recovered enzyme exhibited Raman intensities and enzymic activities similar to the native one. However, the neutralized, bovine enzyme with a similar intensity of the 214 cm-1 line showed increased cytochrome-c-oxidizing activity and null H+-pumping activity.

Animals↗
PubMed1986

Embryological development of human palmar, plantar, and digital flexion creases.

The aim of this study is to document the prenatal stages of development of the flexion creases on the surfaces of the human palm, sole, and digits. We used 160 human fetuses, 6-20 weeks of gestational age, to observe the morphological features of the hand and foot, as well as the period and location of the appearance of the flexion creases. We found that most creases develop concurrently with the appearance of the fetal volar pads and the rest develop independently of them. Furthermore, with some exceptions, the creases seem to develop independently of the flexion movements of hand and foot.

Dermatoglyphics↗
PubMed1986

Effect of recombinant interleukin 2 (R-IL2) on in vivo growth of murine myeloma X5563.

The present study deals with the effect of recombinant interleukin 2 (R-IL2) on in vivo growth of murine myeloma X5563. Administration of R-IL2 (5 X 10(4) J.U./mouse per day) s. c. starting 1 day after X5563 inoculation i.d. had a marginal effect on the growth of X5563, and all the mice repeatedly given R-IL2 from day 1 to day 17 died. However, daily administration of R-IL2 starting 7 days after the tumor inoculation was highly effective and significantly lengthened survival time compared with the control mice injected with vehicle alone. About 50% of the treated mice were completely cured, and survived for more than a month after the therapy ceased. In a representative experiment, where the growth of X5563 was slow because of the small number of inoculated tumor cells, all the mice (n = 6) given R-IL2 from day 11 to day 23 showed complete cure of the established X5563 solid tumor. These mice showed in vivo protective immunity and in vitro cytotoxic T cell responses to X5563 tumor antigens. Histologically, a large number of macrophages and lymphocytes had infiltrated the area around the necrotic X5563 tumor mass in the mice which had received R-IL2 therapy. These results suggest that repeated injections of R-IL2 at the local site after tumor development can augment antitumor immunological responses and subsequently induce tumor regression.

Animals↗
PubMed1986

Annulate lamellae of the pancreatic exocrine cells in starved rats.

The ultrastructure of annulate lamellae in the pancreatic exocrine cells of rats starved for 3-42 days was studied. Annulate lamellae were rarely encountered in the pancreatic exocrine cells of control rats, but their incidence and size of stack was increased in those of starved rats depending on the duration of starvation, despite marked ultrastructural changes in these cells. Annulate lamellae were located in the para- or infranuclear cytoplasm of the cells and most of them were continuous with the relative normal rough endoplasmic reticulum. A close apposition in parallel was often found between the annulate lamellae and the outer nuclear envelope and occasionally pores in line with those of the nuclear membrane were observed in the lamellae of rough endoplasmic reticulum in 35- and 42-day-starved rats. An unequivocal continuity between the annulate lamellae and the nucleus and/or rough endoplasmic reticulum in pancreatic exocrine cells might be related to their origin and function.

Animals↗
PubMed1986

New variant translocation (1;8;21) in a case of acute myeloblastic leukemia (M2).

A new translocation involving chromosome #1, #8, and #21 in a patient with type M2 acute myeloblastic leukemia is reported. The breakpoint of #1 in this case was at band p13 and differed from that in two previously reported cases of t(1;8;21) involving the long arm of #1. A key event leading to the development of the M2 phenotype appears to be a break at band q22 of #8 with associated translocation of the terminal end of the long arm of #21.

Adult↗
PubMed1986

Properties of lysosomal beta-hexosaminidase accumulated in Niemann-Pick mouse liver.

Various lysosomal acid hydrolases from tissues of Niemann-Pick mice, a mutant strain of C57BL/KsJ mice (spm/spm), were examined and compared to those from control mice. Activities of beta-hexosaminidase, beta-galactosidase, acid phosphatase, and cathepsin L were elevated in the liver and spleen of the affected mice, whereas no significant changes in beta-glucosidase and acid alpha-glucosidase were observed. Alpha-Mannosidase and neutral alpha-glucosidase activities were rather decreased in the affected mouse liver. The level of beta-hexosaminidase in the Niemann-Pick mice was raised sixfold in the liver and two- to threefold in the spleen and brain, whereas its total activity was decreased in the kidney. Sixty to ninety percent of total activity of lysosomal hydrolases was solubilized with 0.1% Triton X-100 in control mice, but most of the beta-hexosaminidase activity of the Niemann-Pick mice remained associated with the membrane fraction of liver lysosomes. The beta-hexosaminidase of the Niemann-Pick mice was appreciably stable when heated at 55 degrees C, while hydrolases of the affected mice and all of the enzymes tested in control mice were heat labile. The relative content of two beta-hexosaminidase fractions separated by DEAE-cellulose column chromatography was 8% for beta-hexosaminidase I and 92% for beta-hexosaminidase II in the case of the control mouse liver. The isozyme pattern of hexosaminidases in Niemann-Pick mice was similar to that of control enzymes. However, the beta-hexosaminidase II accumulated in Niemann-Pick mouse liver was different from that of the control in optimum pH, Km values and thermostability.

Animals↗
PubMed1986

Primary hepatocellular carcinoma with hepatitis B virus-DNA integration in a 4-year-old boy.

The autopsy findings in a case of hepatocellular carcinoma with hepatitis B virus (HBV)-DNA integration in a Japanese boy, 4 years and 10 month of age, are reported. The boy was an HBV carrier born in a typical familial cluster of HBV infection in Japan. He had been asymptomatic until the sudden manifestation of the liver tumor. Histopathologic examination revealed a well-differentiated, adult-type hepatocellular carcinoma without hepatic cirrhosis. HBV-DNA sequences were detected in the tumor cell DNA by the Southern blot hybridization method. This is the youngest patient with hepatocellular carcinoma with HBV-DNA integration reported to date, suggesting that HBV may manifest its oncogenic properties after a shorter incubation period than generally believed.

Antigens, Viral↗
PubMed1986

Resonance Raman evidence for oxygen exchange between the FeIV = O heme and bulk water during enzymic catalysis of horseradish peroxidase and its relation with the heme-linked ionization.

Raman spectroscopic studies of compound II of horseradish peroxidase show that the oxygen atom in the FeIV = O group of the heme is rapidly exchanged in H2O at pH 7.0 but not in an alkaline solution (pH 11.0). This conclusion is based on studies of shift in the FeIV = O stretching mode of compound II in H2(18)O; further studies show that the FeIV = O heme is hydrogen-bonded to an amino acid residue of the protein in neutral solutions but not in the alkaline solution. Deprotonation of this residue takes place with the midpoint pH at 8.8 and accordingly corresponds to the so-called heme-linked ionization. It is concluded that this hydrogen-bonded proton plays an important part in the oxygen exchange mechanism. From this it seems clear that this hydrogen-bonded proton has an essential role in the acid/base catalysis of this enzyme and that alkaline deactivation of this enzyme can be attributed to the lack of a hydrogen-bonded proton at high pH.

Catalysis↗