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T Akazawa

Publications and source records attributed to T Akazawa.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Incidence of nausea and vomiting after cholecystectomy performed via laparotomy or laparoscopy].

Postoperative nausea and vomiting (PONV) are commonly observed adverse effects of general anesthesia. In a retrospective study of laparoscopy group (101 patient) and laparotomy group (101 patient), we evaluated the incidence of PONV after laparoscopic cholecystectomy. Most factors which could influence the incidence of PONV were not significantly different between the groups. The overall incidence of PONV during the first 17h postoperatively was 25.7% in laparoscopy group and 18.8% for laparotomy group respectively, but the risk was 3.2 times greater in laparoscopy group (15.8%) than in laparotomy group (5.0%) (P < 0.05) during the first postoperative hour. The risk of PONV was greater in laparoscopy group in female patients (23.4% versus 9.3% in laparotomy group, P < 0.05) and in obese patients (25.0% versus 0% in laparotomy group, P < 0.01) during the first postoperative hour. We conclude that laparoscopic cholecystectomy increases the incidence of PONV in early postoperative period probably by the effect of residual stretching and irritation of the peritoneum, and the risk is increased in female and obese patients.

Anesthesia, General↗
PubMed1992

Artifactual detection of ADP-dependent sucrose synthase in crude plant extracts.

Results presented in a previous report from this laboratory indicated the presence, in crude extracts from sycamore (Acer pseudoplatanus) and spinach (Spinacea oleracea), of a sucrose synthase (EC 2.4.1.13) showing high affinity for ADP as the glucose acceptor in the sucrose-cleaving reaction. In the present paper we report that the modified enzymatic method previously used to measure sucrose synthase activities leads to the detection of artifactual ADP-dependent sucrose synthase, which in fact arises from the combined action of invertase (EC 3.2.1.26) and nucleoside diphosphate kinase (EC 2.7.4.6) activities. We also present data on the partial purification of nucleoside diphosphate kinase from sycamore cells.

Adenosine Diphosphate↗
PubMed1992

Studies on synthetic pathway of xylose-containing N-linked oligosaccharides deduced from substrate specificities of the processing enzymes in sycamore cells (Acer pseudoplatanus L.).

We measured the activities of alpha-1,3-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase, alpha-1,6-mannosyl-glycoprotein beta-1,2-N-acetylglucosaminyltransferase, beta-1,4-mannosyl-glycoprotein beta-1,2-xylosyltransferase and glycoprotein 3-alpha-L-fucosyltransferase in the Golgi fraction of suspension-cultured cells of sycamore (Acer pseudoplatanus L.) using fluorescence-labelled oligosaccharides as acceptor substrates for these transferase reactions. The structures of the pyridylaminated oligosaccharides produced by these reactions were analyzed by two-dimensional sugar mapping using high-performance liquid chromatography. We demonstrated that (formula; see text) was processed to produce by these in vitro reactions. On the basis of these results, we discuss a biosynthetic pathway for xylose containing N-linked oligosaccharides in plant glycoproteins.

Carbohydrate Sequence↗
PubMed1992

A method for accurate analysis of intermembrane space in organelles enclosed by double envelope membranes.

Centrifugal filtration through a double layer of silicone oil was applied to determine the intermembrane space of organelles enclosed by double envelope membranes, i.e. proplastids, chloroplasts, mitochondria and amyloplasts. The organelles, capable of transporting adenylates by an adenylate translocator located in the inner envelope membrane, were incubated with increasing concentrations of adenylates while maintaining their specific radioactivities constant. Intermembrane spaces were estimated by extrapolation of radioactivities recovered after filtration of the organelles. The values estimated were compared to those obtained employing the classical method measuring the intake of [14C]-sucrose and [14C]-sorbitol which are impermeable to the inner membranes of organelles. The intermembrane space determined by the present method was shown to be uniformly smaller than the sucrose-permeable space which was always smaller than the sorbitol-permeable space.

Adenosine Diphosphate↗
PubMed1992

Isolation and characterization of nuclei from rice embryos.

A method has been developed to isolate pure preparations of nuclei in high yield from commercially available viable rice embryos (germ), employing extraction with buffer solution containing glycerol (without detergent) and polyamine, followed by centrifugation on a 30% Percoll cushion. The intactness of the isolated nuclei was confirmed by light microscopy as well as electron microscopy. The protein profiles of both whole nuclei and nuclear extracts obtained by SDS-PAGE, organellar marker enzyme activities, DNA and RNA analyses, and in vitro RNA synthesis, all indicate that the highly purified nuclei are isolated from rice embryos.

Cell Fractionation↗
PubMed1991

ADPG formation by the ADP-specific cleavage of sucrose-reassessment of sucrose synthase.

The standardized enzyme coupling method for assaying sucrose synthase activities in the direction of sucrose cleavage was reexamined using enzyme preparations from cultured cells of sycamore (Acer pseudoplatanus L.) and spinach leaves (Spinacea oleracea). Both ATP and Tris, commonly utilized in assay systems to measure sucrose synthase, were found to inhibit non-competitively the ADPG-synthesizing activities of the enzyme. Upon substituting ATP by either GTP or UTP, and Tris by HEPES, we found that the sucrose synthase is capable of producing ADPG effectively, recognizing ADP as the principal substrate (Km = 5.3 microM (sycamore) and 16.8 microM (spinach]. The Vmax value for the synthesis of ADPG clearly surpasses the Vmax observed for the synthesis of UDPG by the enzyme. It was found that UDP is not inhibitory on the synthesis of ADPG by SS, which behaves allosterically with respect to the concentration level of sucrose.

Adenosine Diphosphate↗
PubMed1991

Comparative analysis of mitochondrial and amyloplast adenylate translocators.

Structurally intact and metabolically competent mitochondria isolated from liquid-culture cells of sycamore (Acer pseudoplatanus L.) were shown to incorporate ADPglucose. Employing the double silicone oil layer filtering centrifugation method, we examined the kinetic properties of the uptake of various adenylates as well as the inhibitory effects exerted by carboxyatractyloside, atractyloside and bongkrekic acid, known specific inhibitors of the mitochondrial adenylate translocator. Immunoblot patterns of peptides derived from the partial proteolytic digestion of the mitochondrial and plastid adenylate translocators were shown to be essentially the same. We conclude that the molecular entities engaged in the adenylate transport system operating in two different organelles, mitochondria and amyloplasts, are very similar.

Adenine Nucleotides↗
PubMed1991

Direct transport of ADPglucose by an adenylate translocator is linked to starch biosynthesis in amyloplasts.

Starch biosynthesis has been studied by using amyloplasts isolated from cultured cells of sycamore trees (Acer pseudoplatanus L.). Highly purified intact amyloplasts, free from mitochondria and starch granules derived from broken amyloplasts, were isolated from a Percoll step gradient. Subsequently, the double silicone oil layer centrifugation technique was used to study adenylate transport in the amyloplasts. An adenylate-specific carrier was found to be active in the uptake of ATP, ADP, AMP, and most importantly, ADPglucose (ADP-Glc). Kinetic analyses showed that the uptake of these adenylates was mutually competitive with each other. In contrast to the mitochondrial adenylate carrier, in amyloplasts only ATP and ADP-Glc uptake were inhibited by carboxyatractyloside. Evidence is presented that the ADP-Glc transported into the amyloplast stroma can be used in starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-D-glucan 4-alpha-D-glucosyltransferase, EC 2.4.1.21). We propose that starch biosynthesis in amyloplasts is tightly coupled with the direct transport of ADP-Glc synthesized in the cytosol by sucrose synthase (ADP-Glc:D-fructose 2-alpha-D-glucosyltransferase, EC 2.4.1.13)

Journal Article↗
PubMed1991

Sequence and expression of genes encoding the large and small subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase from Chromatium vinosum.

A DNA fragment bearing genes for the large (rbcL) and small (rbcS) subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase (RuBisCO) was cloned from the photosynthetic purple sulfur bacterium Chromatium vinosum. Enzymatically fully active RuBisCO was synthesized in Escherichia coli cells when the cloned DNA was placed downstream of tac promoter. Nucleotide (nt) sequences of rbcL-rbcS were more homologous to cyanobacterial counterparts than to those from Alcaligenes eutrophus or higher plants. However, the amino acid (aa) sequence in a domain responsible for CO2 activation in the C. vinosum rbcL product resembled the corresponding aa sequence in higher plant RuBisCos, but not in the cyanobacterial enzymes. Chemically determined aa sequences at the N terminals of both subunits of RuBisCO purified from C. vinosum were not identical to those deduced from the nt sequences, although they were completely the same as aa sequences deduced from rbcA-rbcB, another locus encoding RuBisCO in C. vinosum. Therefore, the rbcL-rbcS locus seems to be barely expressed under a standard condition for photoautotrophic growth. The homology of the nt sequences between rbcL and rbcA was 82%, and that between rbcS and rbcB was 63%, whereas the codon usages of these genes were basically identical. The rbcL-rbcS and rbcA-rbcB loci therefore must have evolved from a common ancestral set of genes after duplication, instead of lateral gene transfer.

Amino Acid Sequence↗
PubMed1991

Characterization and Intraorganellar Distribution of Protein Kinases in Amyloplasts Isolated from Cultured Cells of Sycamore (Acer pseudoplatanus L.).

Incubation of amyloplasts isolated from cultured cells of sycamore (Acer pseudoplatanus L.) with [gamma-(32)P]ATP resulted in the rapid phosphorylation (half-time of 40 seconds at 25 degrees Celcius) of organellar polypeptides. The preferred substrate for amyloplast protein kinases was Mg(2+). ATP, and recovery of only [(32)P]serine after partial acid hydrolysis indicated the predominance of protein serine kinases in the organelle. These activities were located in the envelope and stromal fractions of the plastid, which showed different specificities toward exogenous protein substrates and distinct patterns of phosphorylation of endogenous polypeptides. A 66-kilodalton polypeptide, inaccessible to an exogenously added protease, was one of the major phosphorylated products found in intact amyloplasts at low [gamma-(32)P] adenosine triphosphate concentrations. This polypeptide represented the major phosphoprotein observed with the isolated envelope fraction. The patterns of polypeptide phosphorylation found in intact amyloplasts and chloroplasts from cultured cell lines of sycamore were clearly distinguishable. The overall results indicate the presence of protein phosphorylation systems unique to this reserve plastid present in nonphotosynthetic tissues.

Journal Article↗
PubMed1991

Effects of the gibberellin biosynthetic inhibitor uniconazol on mutants of Arabidopsis.

Using the gibberellin (GA) biosynthetic inhibitor Uniconazol, we determined that det1, a mutant that no longer requires light to be germinated, still requires GA synthesis for germination. This result suggests that dark inhibition of germination in Arabidopsis may be due to inhibition of GA synthesis by the DET1 gene product in mature wild-type seeds. Similar experiments with mutants that lack seed dormancy due to a reduced sensitivity to abscisic acid (abi) have shown that abi1 and abi3 no longer require GA for germination. Furthermore, by shifting wild-type seeds to inhibitor at 6-hour intervals during imbibition, we determined that GA synthesis is only required during the first 24 hours of the imbibition process to reverse abscisic acid-induced dormancy in Arabidopsis.

Journal Article↗
PubMed1991

ADP-Glucose Transport by the Chloroplast Adenylate Translocator Is Linked to Starch Biosynthesis.

In organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (Spinacia oleracea). Immunoblot analysis using a specific antiserum against the mitochondrial adenylate (ADP/ATP) translocator of Neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (Acer pseudoplatanus). The double silicone oil layer-filtering centrifugation technique was employed to study the kinetic properties of adenylate transport in the purified chloroplasts; ATP, ADP, AMP, and most importantly ADP-Glc were shown to be recognized by the adenylate translocator. Similar to the situation with sycamore amyloplasts, only ATP and ADP-Glc uptake was inhibited by carboxyatractyloside, an inhibitor of the mitochondrial adenylate translocator. Evidence is presented to show that the ADP-Glc transported into the chloroplast stroma is utilized for starch synthesis catalyzed by starch synthase (ADP-Glc:1,4-alpha-d-glucan 4-alpha-d-glucosyltransferase). The high activity of sucrose synthase producing ADP-Glc observed in the extrachloroplastic fractions suggests that starch biosynthesis in chloroplasts may be coupled with the direct import of ADP-Glc from the cytosol.

Journal Article↗
PubMed1991

rbcR [correction of rcbR], a gene coding for a member of the LysR family of transcriptional regulators, is located upstream of the expressed set of ribulose 1,5-bisphosphate carboxylase/oxygenase genes in the photosynthetic bacterium Chromatium vinosum.

An open reading frame, rbcR, was identified 226 bp upstream of rbcAB, i.e., the ribulose 1,5-bisphosphate carboxylase genes expressed in the phototrophic purple bacterium Chromatium vinosum. Several features reveal that rbcR encodes a member of the LysR family of transcriptional regulators, in which an anomalous content of lysine and arginine residues (Lys/Arg anomaly) was found. The expression of rbcR in Escherichia coli as a protein fused to the N-terminal region of beta-galactosidase led to reduced expression of rbcAB. Thus, rbcR is likely to encode a trans-acting transcriptional regulator of rbcAB expression in C. vinosum.

Amino Acid Sequence↗
PubMed1991

Filtering centrifugation through two layers of silicone oil: a method for the kinetic analysis of rapid metabolite transport in organelles.

Kinetic studies of ATP uptake in amyloplasts from sycamore (Acer pseudoplatanus L.) have been performed with a newly developed method of centrifugation through a double layer of silicone oil; the results are compared with the frequently used method of centrifugation through a single layer. The present technique employs two separate silicone layers: the upper one prevents mixing of the organelle preparation with the incubation layer, which contains the metabolites, and the lower one prevents mixing of the incubation and pelleting layers. Incubation of the organelles takes place in the incubation layer after the upper layer of silicone inverts during centrifugation. Depending on the speed of centrifugation, incubation periods as short as 1 sec and as long as 2 min can be achieved. High reproducibility and accuracy, acquisition of multiple data in a single centrifugation, and maintenance of structural integrity and metabolic activity of the organelles make the technique advantageous for the analysis of metabolite transport in amyloplasts and other kinds of organelles.

Adenosine Triphosphate↗
PubMed1990

Modulation of DNA methylation and gene expression in cultured sycamore cells treated by hypomethylating base analog.

The selective suppression of photosynthetic genes in both the nuclear and plastid genomes of the nonphotosynthetic white wild-type cell line of sycamore (Acer pseudoplatanus) has been found to be inversely related to the presence of a variety of methylated bases, especially 5-methylcytosine (5-MeCyt) and N6-methyladenine (N6-MeAde), localized in regions of the plastid genome containing silent genes. We used hypomethylating base analogs to manipulate the level of cytosine and adenine methylation in the white cells of sycamore, and examined the effects of changes in methylation on gene expression. Treatment with 5-azacytidine (5-AzaCyd) and N6-benzyladenine (N6-BzlAde) decreased cytosine and adenine methylation. This was accompanied by restoration of transcriptional activity in photosynthetic genes which are usually suppressed. Both 5-MeCyt and N6-MeAde suppressed nuclear gene expression, but only 5-MeCyt suppressed plastid gene expression.

Blotting, Northern↗
PubMed1990

Distinct properties of Escherichia coli products of plant-type ribulose-1,5-bisphosphate carboxylase/oxygenase directed by two sets of genes from the photosynthetic bacterium Chromatium vinosum.

We have recently described the existence of two sets of genes encoding ribulose-1,5-bisphosphate carboxylase/oxygenase (Rbu-P2 carboxylase), rbcA-rbcB and rbcL-rbcS, in the photosynthetic purple sulfur bacterium Chromatium vinosum (Viale, A.M., Kobayashi, H., and Akazawa, T. (1989) J. Bacteriol. 171, 2391-2400). These genes were cloned in plasmid vectors, and their expression was studied in Escherichia coli. Expression of rbcA-rbcB in E. coli was obtained under the control of its own promoter. On the other hand, expression of rbcL-rbcS in this host was not observed unless these genes were cloned under the control of the tac promoter. Purified rbcA-rbcB and rbcL-rbcS products from E. coli consisted of large and small subunits in equimolar ratios. They also showed very close elution profiles to Rbu-P2 carboxylase isolated from C. vinosum in size-exclusion chromatography columns, thus suggesting hexadecameric (L8S8) structures. Vmax of Rbu-P2 carboxylase were very similar for both enzymes, but the Km values for CO2 and ribulose 1,5-bisphosphate showed some differences. Immunochemical and N-terminal amino acid sequence analyses of the large and small subunits encoded by rbcA-rbcB and rbcL-rbcS also differed, especially at the level of the small subunits. The comparisons described above as well as the analysis of C. vinosum crude extracts by anion-exchange chromatography indicated that Rbu-P2 carboxylase encoded by rbcA-rbcB was the only species detected in the photosynthetic bacterium.

Amino Acid Sequence↗