Search PubMed⌕ Search

Biomedical subjects

T Kakuno

Publications and source records attributed to T Kakuno.

At least 19 recordsLinked to original sources
PubMed2001

[Three-dimensional CT angiography of the hepatic artery with multislice CT: differences in image quality according to scanning pitch].

Three-dimensional CT angiography was reconstructed from the hepatic artery using multislice CT, and the effect of pitch during scanning on the quality of obtained images was examined. We randomly divided patients into two groups, with images of one group scanned at helical pitch 3 and images of the other at helical pitch 5.5. CT angiography was reconstructed by a volume-rendering technique. Evaluation was done visually, taking the sharpness of images of branches of the hepatic artery as a measure. Three-dimensional imaging scanned at pitch 3 tended to be better than that scanned at pitch 5.5.

Adult↗
PubMed1998

Generation of triplet and cation-radical bacteriochlorophyll a in carotenoidless LH1 and LH2 antenna complexes from Rhodobacter sphaeroides.

The LH1 antenna complex and a native form of the LH2 complex were isolated from the carotenoidless R26 and R26.1 mutants of Rhodobacter sphaeroides by the use of a new detergent, sucrose monocholate. One-color, pump-and-probe transient Raman spectroscopy of these complexes using 351 nm, approximately 50 ps pulses showed the generation of the triplet state of bacteriochlorophyll a (BChl a), whereas measurements using 355 nm, approximately 12 ns pulses showed the generation of BChl a cation radical. Subpicosecond to nanosecond time-resolved absorption spectroscopy using 388 nm, 200 fs pulses for excitation showed rapid (<1 ps) generation of the triplet state and fast decay (<10 ps) of the singlet state of BChl a. Microsecond absorption spectroscopy confirmed the generation of BChl a cation radical. EPR spectroscopy using 532 nm, approximately 5 ns pulses for excitation established the generation of BChl a cation radical. The EPR line width suggested that the unpaired electron is shared by two BChl a molecules. In LH1, the yield of BChl a cation radical per complex was estimated to be about 80% of that in the reaction center, and in LH2 about 50%. Thus, rapid generation of the triplet state, and its subsequent transformation into the cation-radical state of BChl a have been shown to be intrinsic properties of B870 and B850 BChl a assembly in the carotenoidless LH1 and LH2 antenna complexes. In the case of the carotenoid-containing LH2 complex, the triplet states of BChl a and carotenoid (spheroidene) were generated immediately after excitation, but the triplet-state BChl a was quenched efficiently by the carotenoid so that no BChl a cation radical was generated. Thus, the photoprotective function of the carotenoid in this antenna complex is shown.

Bacterial Proteins↗
PubMed1997

Hepatitis C virus-related liver damage is related to cold activation of complement.

A high positivity of cold activation of complement has been reported in Japanese patients having hepatitis B virus-negative chronic hepatitis. Although the cause of cold activation of complement is unknown, the involvement of hepatitis C virus (HCV) has been suspected. We studied the positivity of cold activation of complement in 253 patients, including 93 patients with chronic hepatitis C infection who received 6MU natural interferon-alpha per day for 24 continuous weeks. Cold activation was positive in 38% of patients with chronic hepatitis C and in 46% of patients with liver cirrhosis C. We did not detect cold activation in asymptomatic HCV carriers; patients with chronic hepatitis B, liver cirrhosis B, or alcohol-related liver damage; or in the controls. Cold activation was also negative in HCV-RNA-negative patients who responded completely to interferon-alpha, and in HCV-RNA-positive patients who responded partially whose serum alanine transaminase levels were normalized after interferon treatment. In the patients who had a relapse of hepatitis C after interferon treatment, positivity of cold activation increased sharply. We conclude that HCV-associated liver damage is related to the development of cold activation of complement. Cold activation is useful for monitoring the response to interferon in patients with chronic hepatitis C infection.

Adult↗
PubMed1993

An open reading frame in the Rhodospirillum rubrum plasmid, pKY1, similar to algA, encoding the bifunctional enzyme phosphomannose isomerase-guanosine diphospho-D-mannose pyrophosphorylase (PMI-GMP).

The nucleotide sequence of a BglII fragment (3188 bp) from the plasmid pKY1 of Rhodospirillum rubrum was determined. A significant similarity was found between the amino acid sequences deduced from the nucleotide sequence of BglII fragment with that of algA, encoding the bifunctional enzyme with both the activities of phosphomannose isomerase and guanosine diphospho-D-mannose pyrophosphorylase of Pseudomonas aeruginosa.

Amino Acid Sequence↗
PubMed1993

Rapid degradation of cucumber cotyledon lipoxygenase.

The lipoxygenase activity from cucumber cotyledons grown with their embryonic axis was separated into two fractions having M(r)s of 90,000 and 96,000, respectively, by hydrophobic chromatography. However, from de-embryonated cucumber cotyledons, only one form of lipoxygenase having a M(r) of 90,000 was purified. The three lipoxygenases could not be distinguished from each other either immunologically or by their enzymatic properties. Furthermore, peptide maps of the 90,000 and 96,000-lipoxygenases were identical. In a crude homogenate of cucumber cotyledons, the 96,000-lipoxygenase was rapidly degraded to the 90,000-form. Thus, it was inferred that the 90,000-lipoxygenase was probably the 96,000-form which had lost a peptide fragment of 6,000. It is suggested that there is a specific proteolytic activity for the degradation of 96,000-lipoxygenase. Estimation of changes in the proteolytic activity during seedling growth suggests that the activity at least partly contributes to the rapid in vivo degradation of cucumber cotyledon lipoxygenase.

Amino Acid Sequence↗
PubMed1993

The complete amino acid sequence of subunit d of rat liver mitochondrial H(+)-ATP synthase.

Subunit d of H(+)-ATP synthase from rat liver mitochondria was isolated from the purified enzyme by reverse-phase high performance liquid chromatography. The partial amino acid sequence of the subunit was determined by automated Edman degradation of the peptide fragments. The nucleotide sequence of subunit d of rat liver H(+)-ATP synthase was determined from a recombinant cDNA clone isolated by screening a rat hepatoma cell line H4TG cDNA library with a probe DNA. The sequence was composed of 581 nucleotides including a coding region for the import precursor of subunit d and noncoding regions on the 5'- and 3'- sides. The possible precursor of subunit d and its mature polypeptide deduced from the open reading frame consisted of 161 and 160 amino acid residues with molecular weights of 18,763 and 18,631, respectively. Subunit d is a hydrophilic protein with an isoelectric point of 6.19. The sequence of the rat subunit d is highly homologous with that of subunit d of bovine heart and slightly similar to that of the subunit d of the yeast mitochondria. However, it had no homology with the sequence of any of the subunits of bacterial or chloroplast H(+)-ATP synthase.

Amino Acid Sequence↗
PubMed1992

Purification and partial characterization of two types of growth-inhibitory protein latently present in rabbit serum.

Normal rabbit serum contained two kinds of growth-inhibitory protein, GI-I and GI-II, in latent forms. These latent inhibitors were activated by incubation at 37 degrees C for 12 h, and their activation was lowered by inhibitors for serine, cysteine and metalloproteinases. Both growth inhibitors were highly purified in active forms by successive column chromatographies. GI-I showed a major protein band with an Mr of 18,000 on sodium dodecyl sulfate-polyacrylamide gel electrophoresis, while GI-II showed a major protein band with an Mr of 36,000. GI-I and GI-II half-inhibited the growth of rat tumorigenic cell line (RSV-BRL) at concentrations of 0.5 ng/ml and 10 ng/ml, excess concentrations. Of the 15 cell lines tested, GI-I specifically inhibited the growth of rodent and lagomorph cells, whereas GI-II nonspecifically inhibited the growth of all cell lines tested. Specificities for cell type and malignancy were not observed with either inhibitor. These growth inhibitors were stable to a reducing reagent and proteinase inhibitors, but labile to urea, acid, organic solvents, trypsin, plasmin and heating at 95 degrees C for 5 min. These properties suggested that both growth inhibitors might be distinct from known growth-inhibitory factors.

Animals↗
PubMed1991

Purification and properties of growth inhibitor from normal rabbit serum.

It was previously found that rabbit serum contains a growth-inhibitory substance for a tumorigenic rat liver cell line RSV-BRL. In the present study, the growth inhibitor was purified from normal rabbit serum to show a homogeneous protein band with a molecular weight (Mr) of 56 k on SDS-polyacrylamide gel electrophoresis under non-reducing conditions. The purified growth inhibitor, tentatively named rabbit serum-derived growth inhibitor (RSGI), potently inhibited the growth of RSV-BRL and nine kinds of other cell lines including three human tumor cell lines at a concentration of 20 ng/ml or higher. The growth-inhibitory effect of RSGI was reversible and appeared to be cytostatic rather than cytotoxic. RSGI was stable to heating at 56 degrees C for 30 min or treatment with 0.1 M 2-mercaptoethanol, but labile to heating at 100 degrees C for 3 min or treatment with 1 M acetic acid (pH 2.3), 6 M urea, 50% (v/v) 1-propanol, or 0.1% (w/v) trypsin. These properties of RSGI suggested that it was different from type beta transforming growth factors, tumor necrosis factor-alpha, and other known growth-regulatory factors.

Animals↗
PubMed1990

Ultraviolet imaging densitometry of unstained gels for two-dimensional electrophoresis.

A system suitable for ultraviolet imaging densitometry of two-dimensional electrophoretic gels that are unstained is described, together with its applications. A flying-spot densitometer linked with a personal computer was used for data acquisition, generation of mapping data, and image processing. Randomly distributed zones of proteins on two-dimensional gels were detected at 280 nm without being stained by two-dimensional scanning, and the densitometric value of each pixel (0.2 x 0.2 mm) was memorized by the computer, which generated a mapping pattern with density contours. The amount and densitometric value of cytochrome c had a linear relationship in the range of 2-200 micrograms. Zone locations of bovine liver proteins separated on two-dimensional gels were indicated on a map expressed in X-Y coordinates, and the pIs and molecular weights could be calculated from the map by use of pI and molecular weight markers on the same gel.

Animals↗
PubMed1990

cDNA cloning and sequencing for the import precursor of coupling factor 6 in H(+)-ATP synthase from rat liver mitochondria.

The nucleotide sequence of the import precursor of coupling factor 6 (factor 6) of rat liver H(+)-ATP synthase has been determined from a recombinant cDNA clone isolated by screening a rat liver cDNA library with a probe DNA. The sequence was composed of 458 nucleotides including a coding region for the import precursor of factor 6 and noncoding regions of both the 5'- and 3'-sides. The import precursor of factor 6 and its mature polypeptide deduced from the open reading frame consisted of 108 and 76 amino acid residues with a molecular weight of 12,494 and 8,927, respectively. The presequence of 32 amino acids could be the import signal peptide which serves to direct the protein into the mitochondrial matrix.

Adenosine Triphosphatases↗
PubMed1990

[Characterization of tumor cell growth inhibitor present in rabbit serum].

Growth inhibitors present in various kinds of sera were surveyed using the rat liver epithelial cell line BRL and its tumorigenic transformant RSV-BRL as indicator cells. This survey revealed that normal rabbit serum contained two types of growth inhibitors: one (GI-A) was more growth-inhibitory on RSV-BRL than BRL, whereas the other (GI-B) vice versa. GI-A was purified 3,000-fold to show a major protein band with Mr 70k on SDS-PAGE. It was an acid-and heat-labile protein and potently inhibited the growth of three kinds of transformed cell lines and two human carcinoma cell lines, but hardly that of non-transformed cell lines, at a dose of 0.5-1.0 micrograms/ml. On the other hand, GI-B was an acid- and heat-stable protein with Mr 25k and was considered to belong to the TGF-beta family.

Animals↗
PubMed1987

DNA polymerase A and its stimulative factor of baker's yeast: purification and characterization.

DNA polymerase A (I or major) and its stimulative factor were purified from 15-20 kg wet weight of baker's yeast by several procedures, which were varied in order to examine the possible occurrence of proteolysis. The extraction was carried out in the presence of 10 or 3 mM phenylmethylsulfonyl fluoride (PMSF), followed by either batchwise adsorption-elution or column chromatography on DEAE-Sepharose (rapid or time-consuming, respectively). These early steps were followed by column chromatographies on DEAE-, CM-, and heparin-Sepharoses, phosphocellulose, and Sephacryl S-300. Preparations of the polymerase obtained by all the procedures described above showed a single protein band at Mr of about 145,000 in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), unless they had been treated with 2-mercaptoethanol (ME). After ME treatment, however, they showed two protein bands at Mr of about 145,000 and 75,000 in SDS-PAGE, except for those obtained by the procedure involving 10 mM PMSF and the batchwise adsorption-elution. All the preparations described above showed practically the same specific activity. This indicates that in intact cells, the polymerase consisted of a single peptide with Mr of about 145,000, and that after cell disruption, it was artificially hydrolyzed in a limited fashion into two peptides with Mr of about 75,000, which were still active and were linked to each other through a disulfide bond. Preparations of the factor obtained by all the procedures described above showed a single protein band at Mr of about 20,000 in SDS-PAGE before and after ME treatment. The relative activities of the purified polymerase were (100%), 123, 21, 37, 196, and 38% with native and denatured salmon sperm DNA, native and denatured calf thymus DNA, poly(dA-dT), and poly(dA).oligo(dT)10, respectively. With the addition of the purified factor, they were 173, 272, 173, 217, 173, and 247%, respectively, i.e., significantly stimulated. The purified factor also stimulated the activity of calf thymus DNA polymerase alpha by 150% with denatured salmon sperm DNA; Km was about 5 X 10(-10)M, practically the same as that of yeast DNA polymerase A. However, it hardly influenced the activities of Escherichia coli enzyme I or Micrococcus luteus enzyme.

DNA Polymerase I↗
PubMed1987

Molecular organization of photochemical reaction complex in chromatophore membrane from Rhodospirillum rubrum as detected by immunochemical and proteolytic analyses.

The molecular organization of photochemical reaction (PR) complex in chromatophores from Rhodospirillum rubrum was studied by a combination of proteolytic analysis with proteinase K followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunochemical analysis with rabbit polyclonal antibodies against its five subunits (H, M, L, alpha, and beta). The preparations used for comparison were reaction center complex (RC) (composed of H, M, and L), PR complex, and chromatophores (closed membranous vesicles of polar lipid bilayer having PR complex buried in the membrane). 1. RC was bound with anti-H, anti-M, and anti-L antibodies, whereas PR complex and chromatophores were bound with anti-H and anti-beta antibodies, but not with the other antibodies. 2. With PR complex, H (Mr 31,000 (31K)) was rapidly degraded into two peptides with Mr of 16K and 14.5K (abbreviated as 16K and 14.5K, respectively), M (27K) into 25.5K, and beta (11K) into 10K. Significantly later, the 25.5K of M was degraded into 24K, L (23K) into 19K, and alpha (12K) into 11K. With chromatophores, H and beta were degraded in a manner similar to that with PR complex, whereas M, L, and alpha were not degraded at all. With RC, H, M, and L were rapidly degraded. 3. With RC, the activity for photooxidation of P870 (photochemical activity) was hardly affected till H, M, and L had been degraded into less than 10K, 24K, and 19K, respectively. With PR complex, the absorbance spectrum due to the bacteriochlorophylls of light-harvesting complex-1 composed of alpha and beta (LH1-Bchl) changed in parallel to the degradation of alpha or 10K (a part of beta). 4. Together with the previous results (Ueda et al. (1985) J. Biochem. 98, 1487-1498), the present findings suggest that: 1) RC is directly surrounded by 12 alpha and further by 12 beta; 2) H and beta are mostly and partially exposed, respectively, on the outer surface of the membranous vesicle; 3) a small part of M is exposed on the inner surface of the membranous vesicle.

Bacterial Chromatophores↗
PubMed1987

Purification of acetylcholine receptor-like protein from fetal calf thymus.

A cobrotoxin binding protein from the fetal calf thymus was isolated by affinity chromatography after solubilization with sodium cholate. The specific activity as a nicotinic acetylcholine receptor (AChR) was determined by assessing the binding to [3H]-alpha-bungarotoxin (BuTx), using the high-pressure liquid chromatography. An AChR-like protein was detected in the amount of 1.39-2.14 nmol per g protein. The first peak of 420k-protein from gel filtration of the eluate of affinity chromatography on a Sephacryl column showed one major polypeptide band with an Mr of 40k, by polyacrylamide gel electrophoresis in sodium dodecylsulfate, two major protein bands with pI 5.4-5.6 and 9.2 by isoelectric focusing, and reacted with sera from patients with myasthenia gravis.

Animals↗
PubMed1986

Preliminary crystallographic study of a ribulose-1,5-bisphosphate carboxylase-oxygenase from Chromatium vinosum.

Crystals of a ribulose-1,5-bisphosphate carboxylase-oxygenase from Chromatium vinosum were obtained with the hanging-drop vapor diffusion technique, using polyethylene glycol 4000 as precipitant. The crystal belongs to the cubic system, space group I432, with unit cell dimension a = 245.9 A. An asymmetric unit includes one-quarter (L2S2, L: large subunit, S: small subunit) of a hexadecameric molecule (L8S8, 544,000 Mr), which is located on the crystallographic point symmetry 222 or 4. The crystal diffracts to at least 3.0 A resolution.

Chromatium↗
PubMed1986

Intermolecular relations of the photosystem II complex in spinach chloroplasts as detected by immunochemical assay.

Polyclonal antibodies were prepared to the subunits of the spinach photosystem II fraction (PS II): p47, p43, p27, p33, p24, and p17. (The protein nomenclature refers to Mr). p47 and p43 are the subunits of reaction center complex, and p27 is light-harvesting chlorophyll protein. p33, p24, and p17 are extractable from PS II with 1 M Tris, and p24 and p17 with 1 M NaCl. With untreated PS II fractions, the antibody to p24 inhibited the photosynthetic oxygen-evolving activity, but not the DCPI-photoreduction activity in the presence of DPC, indicating that p24 played an important role in the former activity. Bindings of the respective antibodies to the PS II treated with sodium dodecyl sulfate were regarded as 100%. To untreated PS II, the bindings were 20-30% for p47, p43, and p27, about 50% for p33, and 70-80% for p24 and p17. To NaCl-washed PS II, the binding to p33 increased by 9%, indicating that p33 was adjacent or bound with p24 or/and p17. To Tris-washed PS II, the binding to p43 increased by 7%, indicating that p43 was adjacent or bound with p33. To PS II treated with 3% of Brij 58, only the binding to p27 increased appreciably. To PS II treated with 1% of octyl glucoside, the binding to p47 was still lower than 50%, whereas those to the other subunits were 74-91%. These values could be a measure of the extents to which the subunits were exposed to the aqueous phase, because of the nature of polyclonal antibodies. These results suggest that in intact PS II, p47, p43, and p27 were in most part buried in the inside, p47 being located at the most central and p27 at the outermost part, whereas p33, p24, and p17 were exposed to the outside by 50-75%.

Antibodies↗
PubMed1986

Effects of NaCl and glycerol on photosynthetic oxygen-evolving activity with thylakoid membranes from halophilic green alga Dunaliella tertiolecta.

It is known that the halophilic green alga Dunaliella tertiolecta grows under hypertonic conditions (with NaCl), which induce the intracellular accumulation of high concentrations of glycerol in order to counterbalance the osmotic change. The effects of NaCl and glycerol on the photosynthetic oxygen-evolving activity of thylakoid membranes prepared from D. tertiolecta were investigated in relation to the dissociation of the membranes. It was found that proteins with Mr of 24,000, 17,000, and 13,000 were dissociated from thylakoid membranes of D. tertiolecta by washing with 1 M NaCl, whereas the photosynthetic oxygen-evolving activity was stimulated 2-fold by 0.1-1.5 M NaCl. The antibodies against spinach 24K and 17K proteins did not cross-react with Dunaliella 24K and 17K proteins, respectively. The salt-tolerant feature of the oxygen-evolving activity with Dunaliella thylakoid membranes may be related to the difference of the properties of these two proteins between D. tertiolecta and spinach. When the membranes were washed with 1 M Tris, proteins with Mr of 50,000 and 31,000 were also dissociated in addition to the 24K and 17K proteins described above. The antibody against spinach 33K protein cross-reacted with 31K protein of D. tertiolecta, showing that Dunaliella 31K protein corresponds to spinach 33K protein. When the membranes were treated with a mixture of 1% cholate and 2% deoxycholate, the oxygen-evolving activity was completely depressed, but the depressed activity was significantly restored by organic solvents. Glycerol and dimethylsulfoxide were the most effective for the restoration.(ABSTRACT TRUNCATED AT 250 WORDS)

Chlorophyta↗