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Biomedical subjects

T Mizoguchi

Publications and source records attributed to T Mizoguchi.

At least 19 recordsLinked to original sources
PubMed1999

p125 is a novel mammalian Sec23p-interacting protein with structural similarity to phospholipid-modifying proteins.

COPII-coated vesicles are involved in protein transport from the endoplasmic reticulum to the Golgi apparatus. COPII consists of three parts: Sar1p and the two protein complexes, Sec23p-Sec24p and Sec13p-Sec31p. Using a glutathione S-transferase fusion protein with mouse Sec23p, we identified a novel mammalian Sec23p-interacting protein, p125, which is clearly distinct from Sec24p. The N-terminal region of p125 is rich in proline residues, and the central and C-terminal regions exhibit significant homology to phospholipid-modifying proteins, especially phosphatidic acid preferring-phospholipase A1. We transiently expressed p125 and mouse Sec23p in mammalian cells and examined their interaction. The results showed that the N-terminal region of p125 is important for the interaction with Sec23p. We confirmed the interaction between the two proteins by a yeast two-hybrid assay. Overexpression of p125, like that of mammalian Sec23p, caused disorganization of the endoplasmic reticulum-Golgi intermediate compartment and Golgi apparatus, suggesting its role in the early secretory pathway.

Amino Acid Sequence↗
PubMed1999

Repression of nitrogenase by ethanol in nitrogen-deprived cultures of Rhodovulum sulfidophilum.

Light-dependent H2 evolution did not occur in nitrogen-deprived cultures of Rhodovulum sulfidophilum in the presence of ethanol. When ethanol was added to cells which had been grown with ammonia, derepression of the nitrogen fixation genes (nifHD) was inhibited at an ethanol concentration of 1 mM. On the other hand, when cells had nitrogenase-catalyzed proton-reducing activity prior to ethanol addition, reduction of the nifHD transcript level did not occur after the addition. In cells grown with ammonia, concomitant addition of an auxiliary oxidant such as dimethylsulfoxide or sodium bicarbonate resulted in derepression of nitrogenase activity in the presence of ethanol. These results suggest that the electron-accepting process is necessary for derepression of nif genes in cultures which use ethanol as the electron donor.

Ammonia↗
PubMed1999

The structure of an aggregate form of bacteriochlorophyll c showing the Qy absorption at 705 nm as determined by the ring-current effects on 1H and 13C nuclei and by 1H-1H intermolecular NOE correlations.

13C-enriched bacteriochlorophyll c (R[E, E] BChl cF) was suspended in chloroform to form an aggregate showing the Qy absorption at 705 nm. (1) The aggregate exhibited several largely split 13C-NMR signals suggesting the presence of non-equivalent BChl c molecules in the form of the piggyback dimer. (2) Changes in the 13C chemical shifts were traced when methanol was titrated to dissolve the aggregate, and the aggregation shifts (in reference to the monomeric state) were determined as a function of the amount of methanol titrated, and they were analyzed empirically. (3) The ring-current effects were calculated based on the loop-current approximation, and the results were compared with the observed aggregation shifts for 13C and 1H nuclei (the 1H aggregation shifts were determined by extrapolation of the data taken from Mizoguchi, T.; Limantara, L.; Matsuura, K.; Shimada, K.; Koyama, Y. J Mol Structure 1996, 379, 249-265). The results showed that the assembly of two straight columns consisting of the piggyback dimer stacked in the antiparallel orientation is the best choice as a model for the B705 aggregate. (4) Three-dimensional F1 13C-edited F3 13C-filtered heteronuclear single-quantum nuclear-Overhauser-effect spectroscopy was applied to the aggregate consisting of a 1:1 mixture of 13C-labeled and unlabeled BChl c in order to selectively detect the intermolecular 1H-1H NOE correlations. The NOE correlations were explained in terms of a straight column, supporting the above model.

Bacterial Proteins↗
PubMed1999

Intraoperative transesophageal echocardiography for evaluation of mitral valve repair.

BACKGROUND AND AIM OF THE STUDY: Although mitral valve repair is a well-established procedure, incorrect assessment of the repaired valve may occasionally lead to the need for reoperation. This study was performed to evaluate the accuracy of color Doppler in assessing the competence of the repaired mitral valve. METHODS: Transesophageal echocardiography (TEE) and left ventriculography were each performed in 72 patients to compare the two techniques and a semi-quantitative index derived. Using this relationship, post bypass intraoperative TEE was then performed in 34 patients who underwent mitral valve repair, in order to assess the competence of the repaired valve. RESULTS: Significant differences were apparent in maximal regurgitant mosaic area between angiographic grade 0, and grades 1+ (p = 0.0006), 1+ and 2+ (p < 0.0001) and 2+ and 3+ (p = 0.0010). A maximal regurgitant area < 2 cm2 predicted angiographic grade as 0 (sensitivity 100%, specificity 95%), an area of 2-4 cm2 as 1+ (sensitivity 82%, specificity 100%), an area of 4-7 cm2 as 2+ (sensitivity 78%, specificity 90%), and an area > 7 cm2 as grade 3+ or 4+ (sensitivity 79%, specificity 93%). All 34 patients completed valve repair with the maximal regurgitant mosaic area < 2.5 cm2. Postoperative left ventriculography showed grade +1 in only five patients; four of these completed mitral valve repair with a maximal mosaic area > 2.0 cm2 as assessed by post bypass intraoperative TEE. During follow up, transthoracic echocardiography (TTE) detected recurrent mitral regurgitation which required mitral valve replacement in one patient, and rapid progression of mitral regurgitation in three patients. CONCLUSIONS: It is important that mitral valve repair should be completed with a maximal mosaic area < 2.0 cm2 as assessed by intraoperative TEE, in order to reduce the need for reoperation.

Adult↗
PubMed1998

Molecular cloning and characterization of three cDNAs encoding putative mitogen-activated protein kinase kinases (MAPKKs) in Arabidopsis thaliana.

We isolated three Arabidopsis thaliana cDNA clones (ATMKK3, ATMKK4 and ATMKK5) encoding protein kinases with extensive homology to the mitogen-activated protein kinase kinases (MAPKKs) of various organisms in the catalytic domain. ATMKK3 shows high homology (85% identity) to NPK2, a tobacco MAPKK homologue. ATMKK4 and 5 are closely related to each other (84% identity). Phylogenetic analysis showed that the plant MAPKKs constitute at least three subgroups. The recombinant ATMKK3 and ATMKK4 were expressed as a fusion protein with glutathione S-transferase (GST) in Escherichia coli. Affinity purified GST-ATMKK3 and GST-ATMKK4 proteins contained phosphorylation activity, which shows that both the ATMKK3 and ATMKK4 genes encode functional protein kinases. Northern blot analysis revealed that the ATMKK3 gene expressed in all the organs. The levels of ATMKK4 and 5 mRNAs were relatively higher in steins and leaves than in flowers and roots. We determined the map positions of the ATMKK3, 4 and 5 genes on Arabidopsis chromosomes by RFLP mapping using P1 genomic clones.

Amino Acid Sequence↗
PubMed1998

Isolation of ATMEKK1 (a MAP kinase kinase kinase)-interacting proteins and analysis of a MAP kinase cascade in Arabidopsis.

In plants, a number of MAP kinase (MAPK), MAPK kinase (MAPKK), and MAPKK kinase (MAPKKK) homologues have been reported. However, there have been no reports of protein-protein interactions between these kinases or molecular analysis of MAPK cascades in higher plants. To analyze a possible MAPK cascade in Arabidopsis thaliana, we took two molecular approaches. One is the two-hybrid screening of ATMEKK1 (a MAPKKK)-interacting proteins; the other is an analysis of physical and functional interactions among isolated MAPK, MAPKK, and MAPKKK homologues from Arabidopsis. In two-hybrid screening using ATMEKK1 as bait, we isolated a novel MAPKK homologue, ATMKK2, a MAPK homologue, ATMPK4, and an unknown protein. ATMKK2 has high sequence similarity with MEK1 (a MAPKK) in Arabidopsis. Based on yeast two-hybrid analysis, we detected protein-protein interactions between ATMEKK1 and ATMKK2/MEK1 (MAPKKs), between ATMKK2/MEK1 and ATMPK4 (a MAPK), and between ATMPK4 and ATMEKK1. ATMPK4 and ATMKK2/MEK1 interacted with two distinct regions of ATMEKK1, the N-terminal regulatory domain and the C-terminal kinase domain, respectively. Coexpression of ATMEKK1 increased the ability of two closely related MAPKKs, ATMKK2 and MEK1, to complement a growth defect of the yeast pbs2 mutant. Coexpression of ATMPK4 and MEK1 complemented a growth defect of the yeast mpk1 and bck1 mutants. By contrast, other combinations of MAPKs and MAPKKs did not suppress these yeast mutations. These results suggest that ATMEKK1, ATMKK2/MEK1, and ATMPK4 may constitute a MAP kinase cascade.

Alanine↗
PubMed1998

Identification of a possible MAP kinase cascade in Arabidopsis thaliana based on pairwise yeast two-hybrid analysis and functional complementation tests of yeast mutants.

A possible MAP kinase (MAPK) cascade of Arabidopsis thaliana was identified on the basis of both yeast 2-hybrid analysis and complementation analysis of yeast mutants. Specific protein-protein interactions between ATMPK4 (a MAPK) and MEK1 (a MAPKK) and interactions between MEK1 and ATMEKK1 (a MAPKKK) were detected by using the 2-hybrid system. A growth defect of the yeast mpk1delta mutant was reversed by coexpression of ATMPK4 and MEK1. Coexpression of the N-terminal deletion form of ATMEKK1 increased the ability of MEK1 to suppress a growth defect of the yeast pbs2delta mutant. These results suggest that ATMPK4, MEK1, and ATMEKK1 may interact with each other and constitute a specific MAPK cascade in Arabidopsis. This is the first demonstration of a possible MAPK cascade in plants.

Arabidopsis↗
PubMed1998

A null lesion in the rhodopin 3,4-desaturase of Rhodospirillum rubrum unmasks a cryptic branch of the carotenoid biosynthetic pathway.

The carotenoids accumulated by a mutant Rhodospirillum rubrum ST4, containing a single Tn5 lesion in the pathway for carotenoid biosynthesis, were analyzed by HPLC, 1H NMR spectroscopy, and field desorption mass spectrometry. The main carotenoid was identified as 3,4,3',4'-tetrahydrospirilloxanthin, and the four minor carotenoids were identified as rhodopin, 3,4-dihydroanhydrorhodovibrin, 3', 4'-dihydrorhodovibrin, and 1,1'-dihydroxylycopene. The C-3,4 and C-3',4' bonds of all 5 carotenoids are saturated, and they have 11 conjugated double bonds. With the exception of rhodopin, which is a normal intermediate of the wild-type pathway, all of the carotenoids are not naturally occurring. The Tn5 lesion was assigned to rhodopin 3,4-desaturase which is proposed to catalyze dehydrogenation at both ends of the symmetrical spirilloxanthin derivative. An unexpected finding was that the enzymes following rhodopin 3,4-desaturase are still able to end-modify the 3,4-, and 3',4'-saturated precursors and that the order of methylation and hydroxylation is not obligatory. It is proposed that the observed nonnatural carotenoids can be explained by the inclusion of a cryptic branch, unmasked by the absence of rhodopin 3,4-desaturase, in the established linear pathway for spirilloxanthin biosynthesis. This is the first example of latent branching of the carotenoid biosynthesis pathway exhibited by a carotenoid mutant of a phototrophic bacterium.

Carotenoids↗
PubMed1998

Broad spectrum and mode of action of an antibiotic produced by Scytonema sp. TISTR 8208 in a seaweed-type bioreactor.

A photobioreactor was constructed using anchored polyurethane foam strips (1 x 1 x 40 cm) fixed onto a stainless-steel ring to prevent flotation, as a biomass support material (BSM). This type of reactor was named a seaweed-type bioreactor. A filamentous cyanobacterium, Scytonema sp. TISTR 8208, which produces a novel cyclic dodecapeptide antibiotic, was immobilized in seaweed-type photobioreactor and cultivated with air containing 5% CO2 sparged at a gas flow rate of 250 mL/min under illumination at a light intensity of 200 mmol photon m-2 s-1. The antibiotic produced in the seaweed-type photobioreactor was purified by HPLC and examined regarding its spectrum and mode of action. The antibiotic effectively inhibited the growth of Gram-positive bacteria, pathogenic yeasts, and filamentous fungi, but it had only a weak effect on Gram-negative bacteria. Scanning electron micrograph analysis showed that the most characteristic change was swelling of the cells after exposure to the antibiotic. The antibiotic seems to alter the conformation of the microbial cell membrane, thereby changing its permeability, leading to osmotic shock.

Anti-Bacterial Agents↗
PubMed1998

Cloning and sequence analysis of the poly (3-hydroxyalkanoic acid)-synthesis genes of Pseudomonas acidophila.

Pseudomonas acidophila can grow with CO2 as a sole carbon source by the possession of a recombinant plasmid that clones genes that confer chemolithoautotrophic growth ability derived from the H2-oxidizing bacterium Alcaligenes hydrogenophilus. H2-oxidizing bacteria produce poly(3-hydroxybutyric acid) (PHB) from CO2, but recombinant P. acidophila can produce the more useful biopolymer poly(3-hydroxyalkanoic acid) (PHA). In this study, the pha genes of P. acidophila were cloned and a sequence analysis was carried out. A gene library was constructed using the cosmid vector pVK102. A recombinant cosmid carrying the pha genes was selected by the complementation of a PHB-negative mutant of Alcaligenes eutrophus H16. The resulting recombinant cosmid pIK7 contained a 14.8-kb DNA insert. Subcloning was done. and the recombinant plasmid pEH74 was selected by hybridization with the A. eutrophus H16 pha genes. Escherichia coli possessing pEH74 produced PHB, indicating that pEH74 contained the pha genes of P. acidophila. The nucleotide sequences of the PHA-synthesis genes phaA (beta-ketothiolase), phaB (acetoacetyl-CoA reductase), and phaC (PHA synthase) in pEH74 were determined. The homologies of phaA, phaB, and phaC between P. acidophila and A. eutrophus H16 were 64.7, 76.1 and 56.6%, respectively.

Acetyl-CoA C-Acyltransferase↗
PubMed1998

Quantitative electroencephalographic correlates of cerebral blood flow in patients with chronic subdural hematomas.

BACKGROUND: We have observed that the reduction in cerebral blood flow (CBF) of patients with chronic subdural hematomas is always most pronounced in the thalamus and has a linear correlation with the degree of brain deformity caused by the compression from the hematoma. When the brain is markedly displaced by a hematoma, electroencephalography (EEG) shows delta waves in the frontal region. We theorized that the flow reduction begins in the thalamus, spreading throughout the hemisphere as displacement progresses. METHODS: We measured CBF using the xenon/computed tomography (CT) method in 10 patients with chronic subdural hematomas who had hemiparesis and/or a mental disturbance and radiographic evidence of a midline shift or herniation. We correlated their flow reductions with topographic encephalograms. RESULTS: Flow reductions were more pronounced in the thalamus than in the hemisphere and cortex. Slow waves dominated over fast waves, especially in the frontopolar and frontal regions bilaterally. Flow values correlated negatively with the presence of delta and theta waves and positively with that of alpha and beta waves. On the side of the hematoma, the brain wave activity correlated significantly with thalamic flow, and the correlation was greater than with the hemispheric or cortical flow. Thalamic flow correlated more consistently with delta and alpha waves in the central, temporal, and occipital regions, and with beta waves in the frontopolar, frontal, and central regions. On the nonhematoma side, the correlation between brain wave activity and hemispheric flow was significant and greater than with cortical or thalamic flow. CONCLUSIONS: The correlation of EEGs with thalamic flow, which was maximally reduced, seems to substantiate the concept that the thalamus is primarily injured by brain distortion due to the compression from hematoma and that the remote areas are secondarily deactivated by a transneural depression ("diaschisis") originating from the dysfunctioning thalamus. Thalamic involvement seems to be the cause of the neurologic dysfunction and the abnormal EEG activity in chronic subdural hematomas.

Aged↗
PubMed1998

Phacoemulsification, intraocular lens implantation, and trabeculotomy to treat pseudoexfoliation syndrome.

PURPOSES: To determine the long-term risk/benefit ratio of phacoemulsification and intraocular lens (IOL) implantation combined with trabeculotomy to manage eyes with pseudoexfoliation syndrome and co-existing cataract. SETTING: Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine; Kurihara Eye Clinic; Departments of Ophthalmology, Tenri Hospital, Kumamoto University, and Matsue Red Hospital; Nagata Eye Clinic, Japan. METHODS: This multicenter retrospective study comprised 49 eyes of 36 patients with pseudoexfoliation syndrome and co-existing cataract who had the combined procedure for uncontrolled intraocular pressure (IOP) (> 21 mm Hg) even on antiglaucoma medication. RESULTS: After a mean follow-up of 20.0 months +/- 13.2 (SD), IOP in all 49 eyes was well controlled (< or = 21 mm Hg). Mean IOP at the final examination was 14.6 +/- 2.6 mm Hg on a mean of 0.9 +/- 0.8 glaucoma medications. Complications included an IOP spike in 11 eyes and fibrin exudation in 1 eye. CONCLUSION: Phacoemulsification and IOL implantation combined with trabeculotomy was an effective treatment for patients with pseudoexfoliation syndrome and cataract.

Aged↗
PubMed1998

The glycosylation sites and structural characteristics of oligosaccharides on recombinant human thrombomodulin.

Thrombomodulin (TM) is an anticoagulant glycoprotein on the surface of endothelial cell that directly inhibits the procoagulant activities of thrombin, and the TM-thrombin complex accelerates thrombin-catalyzed activation of protein C. Soluble TM in urine has no glycosaminoglycan (GAG) chain which accelerates the anticoagulant activities. Therefore, we expressed recombinant GAG-modified urinary thrombomodulin (GAG-UTM) in C127 cells. The glycosylation sites were determined by amino acid sequence analysis of peptides digested with trypsin after S-carboxymethylation. The structures of N-linked oligosaccharides were estimated by two-dimensional sugar mapping of pyridylaminated oligosaccharides that were treated with exoglycosidase. The disaccharide composition analysis of the GAG chain was performed by HPLC using digestion with chondroitinase ABC, ACII and B. Consequently, it was revealed that the N-linked oligosaccharides were assigned to Asn29, Asn98, Asn364, Asn391; those structures were estimated biantennary, 2-6 branched triantennary and 2-4 branched triantennary complex type oligosaccharides that were linked by fucose at the ratio of 1.0:0.5:0.1, respectively. Moreover, the attachment site of the GAG chain was assigned to Ser472. It was then estimated that the GAG chain contained chondroitin-4-sulfate and dermatan sulfate, which were repeated approximately 30 times. In this paper, the GAG attachment site and structural characteristics of GAG-UTM, were confirmed. Moreover, structures of the N-linked oligosaccharides of GAG-UTM are described for the first time.

Amino Acid Sequence↗
PubMed1998

D-erythrulose reductase can also reduce diacetyl: further purification and characterization of D-erythrulose reductase from chicken liver.

We have discovered new characteristics of D-erythrulose reductase, namely, that it can catalyze reduction of not only D-erythrulose but also such diketones as diacetyl. These substrates have a common structure with two neighboring carbonyls possibly in s-cis plane structure, showing that the enzyme may rigorously distinguish between substrates and other compounds. D-Erythrulose reductase was predominantly located in the kidney and the liver of the chicken. The obtained results suggest that D-erythrulose reductase plays an important role in metabolizing alpha-dicarbonyls in animal organs, because these diketones widely occur in natural foods.

Animals↗
PubMed1998

Importance of sialic acid in recombinant thrombomodulin in terms of pharmacokinetics and separation of desialyzed glycoprotein.

Recombinant glycosaminoglycan-modified urinary thrombomodulin (GAG-UTM) expressed in mouse C-127 cells has potent antithrombotic activity available as an anticoagulant. GAG-UTM, a glycoprotein with sialic acid, was investigated regarding the influence of the terminal sialic acid on its pharmacokinetics upon rapid intravenous injection in rat. Asialo GAG-UTM desialated by neuraminidase was cleared rapidly from plasma. Sialyzed GAG-UTM, a sialyzed asialo GAG-UTM with alpha-2, 6-sialyltransferase, containing sialic acid similarly to native sialo GAG-UTM, had only a short half-life in plasma, suggesting that the binding site of sialic acid on galactose was not only sialyzed with alpha-2, 6-sialyltransferase but also with 2, 3-sialyltransferase. Asialo GAG-UTM with oxidized terminal galactose, however, had a long half-life. These results suggest that terminal sialic acid may be important to the pharmacokinetics of GAG-UTM; therefore, an analysis of asialo GAG-UTM became significant for quality control. In order to analyze sialo- and asialo-types in the early stage of purification, we investigated separation and analysis methods for both types and found a suitable sample of each: RCA-120-Agarose column for separation and ELISA using anti-thrombomodulin antibody and RCA lectin for analysis.

Animals↗
PubMed1998

Intraoperative management for removal of tumor thrombus in the inferior vena cava or the right atrium with multiplane transesophageal echocardiography.

BACKGROUND: To investigate the role and impact of multiplane transesophageal echocardiography during thrombectomy in the inferior vena cava or the right atrium. EXPERIMENTAL DESIGN: Retrospective. SETTING: A university hospital. PARTICIPANTS: Four patients who underwent removal of tumor thrombus in the inferior vena cava (IVC) or the right atrium. INTERVENTIONS: The medical records of 4 patients and videotapes of these intraoperative transesophageal echocardiography examinations were reviewed. RESULTS: Before thrombectomy, multiplane transesophageal echocardiography (MTEE) provided excellent IVC long axis view, which offered precise recognition of the cephalic extent of tumor, extent of caval occlusion, characterization of the tumor head. During surgery, MTEE could provide continuous monitoring of cardiac function, cardiac volume, and pulmonary embolism. Moreover, MTEE could provide the useful images of a cannula or the caval occlusion balloon catheter, which facilitated removal of neoplasm extending into the IVC. CONCLUSIONS: We presented four surgical cases, in which the removal of the tumor extended into the inferior vena cava or the right atrium using MTEE. MTEE could provide valuable information such as excellent images of the tumor, cardiac function, the position of a cannula or the caval occlusion balloon catheter. These findings could improve the anesthetic management of the patients, as well as the surgical approach and technical maneuvers, and facilitate removal of neoplasm into the IVC.

Adult↗