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Biomedical subjects

K Sugimoto

Publications and source records attributed to K Sugimoto.

At least 307 records · Page 17Linked to original sources
PubMed1996

Mouse MCM proteins: complex formation and transportation to the nucleus.

BACKGROUND: The members of the MCM protein family, including MCM2, MCM3, Cdc21, CDC46, Mis5 and CDC47, are considered to be involved in the control of a single round of DNA replication during S phase in eukaryotes. They bind to chromatin during G1 and detach from it during S phase as if they license the chromatin to replicate. However, unlike the originally proposed 'licensing factor' and the budding yeast homologues, mammalian MCM2 and P1MCM3 proteins appeared to be localized in the nucleus during the interphase. RESULTS: We purified mCdc21 and its associated proteins from mouse cell extract by anti-mCdc21 immunoaffinity chromatography. Three proteins which co-purified with mCdc21 were identified as mCDC47, mMis5 and mMCM2, all were MCM proteins. Glycerol gradient centrifugation analysis showed that all the mouse MCM proteins were detected at 450-600 kDa, an indication of the sum of their calculated molecular weights from their amino acid sequences. mCdc21 was displaced from replicated chromatin in a similar way to P1MCM3 and MCM2 during S phase. Among the six mouse MCM proteins, only mMCM2 and mP1MCM3 showed nuclear localization when overexpressed in COS cells. CONCLUSIONS: We conclude that in the mouse, six MCM proteins form a single protein complex of molecular weight 450-600 kDa, which may enter the nucleus by nuclear localization signals in the mMCM2 and mP1MCM3 subunits.

Amino Acid Sequence↗
PubMed1996

Human homolog of Drosophila heterochromatin-associated protein 1 (HP1) is a DNA-binding protein which possesses a DNA-binding motif with weak similarity to that of human centromere protein C (CENP-C).

Heterochromatin-associated protein 1 (HP1) is a nonhistone chromosomal component tightly associated with the pericentromeric heterochromatic region of fruit fly, mouse, and human throughout the cell cycle. Drosophila HP1 has been shown to be involved in position effect variegation and to be required for the correct chromosome segregation in vivo, while the biological activity of human homolog (HP1Hsa) has not yet been characterized. We previously reported that human CENP-B and CENP-C, two major centromere heterochromatin autoantigens often recognized by autosera in scleroderma patients, possess DNA-binding activity in vitro. Here, we show that human HP1, which is also an autoantigen targeted by some types of anticentromere autosera, is a DNA-binding protein. Human HP1 was expressed as a GST-fusion in Escherichia coli and purified with glutathione-Sepharose. The DNA-binding activity of the recombinant HP1 was demonstrated by gel mobility shift assay and South-Western-type blotting. The minimum DNA-binding region was further limited to the internal 64-amino acid stretch that is less-conserved between human and fruit fly but retains a helix-enriched motif with weak similarity to CENP-C. This suggests that HP1 is involved in the pericentromeric heterochromatin formation by directly associating with genomic DNA.

Amino Acid Sequence↗
PubMed1996

Purification and characterization of the Proteus vulgaris BlaA protein, the activator of the beta-lactamase gene.

Induction of the expression of the beta-lactamase gene, blaB, is regulated by the blaA gene located just upstream of blaB in the opposite direction in Proteus vulgaris. The expression of the blaA gene is negatively autoregulated by its own product BlaA, the activator of the blaB gene. The P. vulgaris BlaA protein shares high amino acid homology with the LysR family members, which are prokaryotic transcriptional activators that possess a putative helix-turn-helix DNA binding motif. To characterize its function, we purified the BlaA protein to homogeneity from Escherichia coli carrying the expression plasmid of the blaA gene driven by the tac promoter. The gel shift assay and DNaseI footprinting showed that purified BlaA specifically bound to the blaA promoter region, which resides immediately upstream of that of blaB. The binding region contained an inverted repeat, including a T-N11-T sequence which is similar to the LysR motif (T-N11-A) that is conserved in some LysR family members [Goethals et al. (1992) Proc. Natl. Acad. Sci. USA 89, 1646-1650]. We also showed that the BlaA protein forms a dimer in solution, using glycerol gradient centrifugation and glutaraldehyde crosslinking.

Bacterial Proteins↗
PubMed1996

Morphological and cytoskeletal changes in endothelial cells of vein grafts under arterial hemodynamic conditions in vivo.

To understand venous endothelial adaptation to arterial hemodynamics in vivo, changes in surface morphology and stress fiber distribution in the endothelial cells of an autologous vein graft transplanted to a rabbit femoral artery were investigated by scanning electron microscopy and confocal laser scanning microscopy, respectively. After transplantation, the shape index (length of cellular long axis/short axis) of the endothelial cells in the graft was intermediate between those of control arteries and veins, and persisted almost unchanged up to week 16. In contrast, the expression of intracellular stress fibers changed; stress fibers of the endothelial cells in the graft were rare shortly after the operation, but gradually developed and increased both in number and thickness, to a level similar to that in the control arterial endothelial cells by week 16. These results suggest that venous endothelial cells, subjected to hemodynamic change, maintain their shape through stress fiber development.

Actin Cytoskeleton↗
PubMed1996

Role of repeat computed tomography after emergency endoscopic retrograde pancreatography in the diagnosis of traumatic injury to pancreatic ducts.

Endoscopic retrograde pancreatography (ERP) is performed on patients with pancreatic injury after abdominal trauma. To delineate pancreatic ductal injuries more accurately, we performed repeat computed tomography (CT) shortly after completion of ERP. We describe our experiences with six patients to demonstrate the feasibility and utility of this method. In our cases, the diagnosis of pancreatic ductal injury was made with certainty on the basis of the presence of extravasated contrast medium. This protocol is useful for reaffirmation of injuries noted on ERP, for diagnosis of injuries not noted on ERP, and for exclusion of injuries in patients with equivocal results of ERP. Moreover, the protocol is easy to implement because it involves only the transfer of the patient from the endoscopy to the CT suite. The technique can be used to clarify potentially confusing situations.

Abdominal Injuries↗
PubMed1996

Release site of TNF alpha after intravenous and intraperitoneal injection of LPS from Escherichia coli in rats.

Lipopolysaccharide (LPS) concentrations in the portal vein after intraperitoneal (i.p.) injection were slightly higher than those in the arteries. The tumor necrosis factor (TNF alpha) levels in arterial serum were higher after i.p. injection than after i.v. injection and rose to a peak at 90 min after some delay. Infusion of LPS into the portal vein increased the TNF alpha levels in the arterial serum. Pretreatment with indomethacin further increased the arterial levels of TNF alpha after portal infusion, but did not after them after i.p. injection, because of the reduction by indomethacin of LPS absorption after i.p. Injection of LPS. TNF alpha was also generated in the peritoneal cavity after i.p. injection of LPS. The TNF alpha concentrations in the arterial serum and in the peritoneal cavity were accelerated by mast cell degradation. In conclusion, TNF alpha was generated mainly in the liver, but also in the peritoneal cavity, after i.p. injection of LPS, and was negatively regulated by prostaglandins.

Animals↗
PubMed1996

Autonomous transposition of the tobacco retrotransposon Tto1 in rice.

The complete nucleotide sequence of the tobacco retrotransposon Tto1, one of the few active retrotransposons of plants, was determined. The sequence analysis suggests that Tto1 carries all functions required for autonomous transposition through reverse transcription. Gene organization and the nature of the transcription product suggest that Tto1 uses a gene expression mechanism different from those employed by retroviruses and most retrotransposons to regulate Gag and Pol stoichiometry. Tto1 was introduced into rice to study its autonomous transposition in heterologous hosts. Transcription and transposition of Tto1 were observed in rice cells. To probe the autonomous transposition through reverse transcription, a modified Tto1 retrotransposon in which part of a reverse transcriptase gene was replaced with an intron-containing hygromycin resistance gene was constructed and introduced into rice cells. Loss of the intron was observed only when intact Tto1 was cotransfected. These results indicate that Tto1 can transpose autonomously through reverse transcription and that the host factors required for transposition are conserved among monocots (class Magnoliopsida; rice) and dicots (class Liliopsida; tobacco), which diverged approximately 200 million years ago. These findings are discussed in relation to the regulation and evolution of retrotransposons and the possible use of Tto1 as a molecular genetic tool.

Base Sequence↗
PubMed1996

AT1 receptor antagonist, TCV 116, does not prevent cardiac hypertrophy in salt-loaded Dahl salt-sensitive rats.

1. We investigated the effects of direct blockade of angiotensin II (AngII) by a potent, non-peptide angiotensin II toff 1 (AT1) receptor antagonist, TCV 116, on the development of cardiac hypertrophy in salt-loaded Dahl salt-sensitive rats. 2. Six week old male Dahl salt-sensitive rats (n = 44) were fed a 4% salt diet and were simultaneously given various doses of TCV 116 orally for 7 weeks. Each control group received vehicle alone. 3. Dietary high salt intake elevated blood pressure continuously and caused left ventricular hypertrophy in rats treated with vehicle. TCV 116 had a minor effect on the rise in blood pressure. Left ventricular mass (left ventricular weight/body-weight) decreased slightly but not significantly, in rats treated with 3 mg/kg per day of TCV 116 (n = 8). Higher doses of TCV 116 (6 and 10 mg/kg per day; n = 8 each) did not show a decrease in left ventricular mass compared with the vehicle control. 4. These results suggest that AngII blockade has only minor effects on hypertension and on cardiac hypertrophy in salt-loaded Dahl salt-sensitive rats and that the renin-angiotensin system may not contribute to the development of cardiac hypertrophy in Dahl salt-sensitive rats on a moderately high-salt diet.

Angiotensin Receptor Antagonists↗
PubMed1996

Argyrophilic nucleolar organizer regions in colorectal malignancy: application of typing by their density.

Colorectal neoplasms obtained at colonoscopy were examined by argyrophilic nucleolar organizer region (AgNOR) staining to evaluate the usefulness of AgNOR as a discriminant for malignancy. AgNOR dots were divided into two kinds: 'structures' (larger and less-densely stained) corresponding to the nucleolus, and 'units' (smaller and densely stained) presumed to be true AgNOR within the structure. The number of structures per nucleus did not differ between the adenoma and carcinoma groups, whereas the number of units per nucleus showed a significant difference. However there were several cases showing an overlap between the adenoma and carcinoma groups, leading to a difficulty in deciding whether any given case was benign or malignant. Three types of AgNOR patterns were categorized based on the ratio of units to structure. Type I was defined as the unit being indistinguishable from the structure, Type II as each structure having one to five units, and Type III as at least one structure having six or more units, irrespective of total number of units per nucleus. The colorectal lesions in which more than half of the neoplastic cells showed Type III coincided well with carcinomas histologically diagnosed, with the exception of adenomas with severe atypia. Labeling index of proliferating cell nuclear antigen (PCNA LI) differed between the adenoma and carcinoma groups with a considerable extent of overlap, and correlated to some extent with the AgNOR values. These results showed that the AgNOR staining was useful for determining malignancy and its usefulness appeared superior to PCNA LI.

Adenoma↗
PubMed1996

[The etiology of acute lower respiratory tract infections in infants].

The etiology of acute lower respiratory tract infections (ALRI) was studied in pediatric inpatients under 2 years of age admitted to Chiba Municipal Hospital between June 1994 and March 1995. Eighty-seven patients, 99 episodes were investigated for bacterial infection with the use of blood culture and washed sputum culture, for viral infection with the use of virus isolation, antigen detection and antibody assays, for Mycoplasma pneumoniae infection with the use of antibody assay and for Chlamydia infection with the use of antigen detection. Pathogens were identified in 71 (71%) of the 99 episodes. Evidence of bacterial infection was detected in 43 episodes (43%), viral infection in 37 episodes (37%), Mycoplasma pneumoniae infection in 4 episodes (4%) and Chlamydia infection 3 episodes (3%). The major bacterial pathogens were H. influenzae, M. (B) catarrhalis and S. pneumoniae. RS virus and influenza virus epidemics occurred during the winter. A mixed bacterial and viral infection was documented in 13 episodes (13%). RS virus infection was common in infants up to 6 months old. Mixed bacterial and influenza virus infections were common in 1 or more year old children. Virus isolation was useful for the grasp of the viral epidemic. Bacterial associated infections were common in children under 2 years of age with ALRI. Washed sputum culture and sputum gram stains' were useful for the treatment of infant ALRI.

Acute Disease↗
PubMed1996

Antifungal azoxybacilin exhibits activity by inhibiting gene expression of sulfite reductase.

Azoxybacilin, produced by Bacillus cereus, has a broad spectrum of antifungal activity in methionine-free medium and has been suggested to inhibit sulfite fixation. We have further investigated the mode of action by which azoxybacilin kills fungi. The compound inhibited the incorporation of [35S] sulfate into acid-insoluble fractions of Saccharomyces cerevisiae under conditions in which virtually no inhibition was observed for DNA, RNA, or protein synthesis. It did not interfere with the activity of the enzymes for sulfate assimilation but clearly inhibited the induction of those enzymes when S. cerevisiae cells were transferred from rich medium to a synthetic methionine-free medium. Particularly strong inhibition was observed in the induction of sulfite reductase. Northern (RNA) analysis revealed that azoxybacilin decreased the level of mRNA of genes for sulfate assimilation, including MET10 for sulfite reductase and MET4, the transactivator of MET10 and other sulfate assimilation genes. When activities of azoxybacilin were compared for mRNA and enzyme syntheses from MET10, the concentration required for inhibition of transcription of the gene was about 10 times higher (50% inhibitory concentration = 30 micrograms/ml) than that required for inhibition of induction of enzyme synthesis (50% inhibitory concentration = 3 micrograms/ml). The data suggest that azoxybacilin acts on at least two steps in the expression of sulfite reductase; the transcriptional activation of MET4 and a posttranscriptional regulation in MET10 expression. We conclude that azoxybacilin exhibits antifungal activity by interfering with the regulation of expression of sulfite reductase activity.

Aminobutyrates↗
PubMed1996

Recovery of active beta-lactamases from Proteus vulgaris and RTEM-1 hybrid by random mutagenesis by using a dnaQ strain of Escherichia coli.

Proteus vulgaris and RTEM-1 beta-lactamases that belong to molecular class A with 37% amino acid similarity were examined to find the relationship between amino acid residues and activity of enzymes. MICs of ampicillin were > 2,000 micrograms/ml for Escherichia coli cells producing these enzymes. We have made 18 hybrid genes by substituting the coding region of the P. vulgaris beta-lactamase gene with the equivalent portions from the RTEM-1 gene. Most of these hybrids produced inactive proteins, but a few hybrid enzymes had partial or trace activity. From one of the hybrid genes (MIC of ampicillin, 100 micrograms/ml), we recovered three kinds of active mutants which provided ampicillin MICs of 1,000 micrograms/ml by the selection of spontaneous mutations in a dnaQ strain of E. coli. In these mutants, Leu-148, Met-182, and Tyr-274 were replaced with Val, Thr, and His, respectively. These amino acids have not been identified as residues with functional roles in substrate hydrolysis. Furthermore, from these hybrid mutants, we obtained a second set of mutants which conferred ampicillin MICs of 1,500 micrograms/ml. Interestingly, the second mutations were limited to these three amino acid substitutions. These amino acid residues which do not directly interact with substrates have an effect on enzyme activity. These mutant enzymes exhibited lower K(m) values for cephaloridine than both parental enzymes.

Amino Acid Sequence↗
PubMed1996

Effects of a prescription of Chinese herbal medicine on snake venom-induced nephropathy in mice.

A prescription of Chinese herbal medicine, tentatively named P-19, was examined for its inhibitory effect and its mechanism using an experimental model of nephropathy induced by purified snake venom proteinase, Ac(1)-proteinase (Ac(1)-P). The treated mice were injected with 0.1 ml of crude extract of P-19 intraperitoneally every other day beginning 2 d before to 1 week after the injection of Ac(1)-P. The non-treated mice were injected with saline instead of the medicine P-19. The physiological condition and histopathological observation of the mice at one week after Ac(1)-P injection were better in the treated group than in the non-treated group. This indicates that P-19 inhibited the production of glomerular lesions induced in mice by Ac(1)-P. The physiological condition and histopathological changes in the mice were better with P-19 treatment than with P-3 treatment. Differences in the mechanism of action between the crude extract of P-3 and P-19 are not only in diuretic action but also in the changes in the glomerular basement membrane. On the basis of spectrophotometric studies, phenolic carboxylates were confirmed to be contained in the crude extract of P-19, having a different chemical structure of caffeic acid, which is the effective component in P-3. Immunohistochemical observation revealed a difference between the groups. In the non-treated mice, deposits of the venom were clearly observed in the glomerular tuft and Bowman's capsule, corresponding to the histopathological changes, within 2.5 min after the injection of Ac(1)-P. In the treated mice, the deposits were indistinct in the Bowman's capsule. The difference was considered to be caused by changes in the glomerular basement membrane after P-19 treatment.

Agkistrodon↗
PubMed1996

Oral administration of insulin as poly(vinyl alcohol)-gel spheres in diabetic rats.

The oral administration of insulin in poly(vinyl alcohol)-gel spheres (PVA-GS), an oral dosage form with prolonged residence time in the ileum, was examined in streptozotocin-induced diabetic rats. Intragastric administration of PVA-GS containing insulin and a protease inhibitor, aprotinin or bacitracin, caused a significant and prolonged reduction of blood glucose levels, suggesting insulin absorption. The bioavailability of insulin estimated from the hypoglycemic effect was about 2% in the presence of either protease inhibitor. The release profiles of insulin and the protease inhibitors from the PVA-GS could be explained by Higuchi's plot, and the rates were similar to each other. The site dependency of insulin absorption in the intestinal tract was examined by an in situ loop method. Insulin absorption estimated by plasma insulin levels was larger in the ileum and the large intestine than in the jejunum. The prolonged residence time of PVA-GS in the absorption site, the lower intestine, and the synchronous release of insulin and the protease inhibitors from the PVA-GS are the two major explanations for the improved bioavailability of insulin administered as PVA-GS containing a protease inhibitor.

Administration, Oral↗
PubMed1996

Structures and activity of cellulase inhibitors enzymatically synthesized from cellooligosaccharides and 1-deoxynojirimycin.

Cellulase inhibitors were synthesized from cellooligosaccharides and 1-deoxynojirimycin (DNJ) by transglycosylation, using a commercial cellulase. The structures of these cellulase inhibitors were proved to be 4-O-beta-cellobiosyl-DNJ, 4-O-beta-D-glucopyranosyl-DNJ and 6-O-beta-cellobiosyl-DNJ by the results of 13C- and 1H-NMR analyses. The inhibitory activity of each inhibitor was investigated against several carboxymethylcellulases.

1-Deoxynojirimycin↗
PubMed1996

Capacity of H2O2 release from monocytes in steroid-sensitive nephrotic syndrome.

The pathogenesis of steroid-sensitive nephrotic syndrome (SSNS) is poorly defined. We previously demonstrated that monocytes from SSNS patients with proteinuria were activated to display exaggerated phagocytosis of opsonized particles and paradoxically reduced chemotaxis. In this study, we evaluated the capacity of hydrogen peroxide (H2O2) release from monocytes in 19 patients with SSNS and 13 healthy controls, by exposure to phorbol myristate acetate (PMA), using scopoletin method. Of 19 patients of SSNS, 7 were proteinuric and 12 in remission. The H2O2 release was significantly higher in SSNS patients with proteinuria than those in remission or normal controls [177.49 +/- 94.75 (mean +/- S.D.) vs. 60.67 +/- 58.89 (p < 0.02) or 85.02 +/- 48.62 nmol/90 min/mg cell protein (p < 0.05)]. Follow-up measurements in two SSNS patients showed that H2O2 release was reduced when proteinuric condition was improved to be in remission. Our data suggest that monocytes in SSNS with proteinuria were activated and were prepared to receive some extracellular signaling leading to protein kinase-C activation for releasing H2O2.

Adult↗
PubMed1996

Off-depolarization and off-hyperpolarization after termination of quinine-HCl stimulation in frog taste cells.

Off-responses in frog taste cells evoked by a Ringer rinse following 1 mM quinine-HCI (Q-HCl) stimulation were investigated with an intracellular recording technique. Three types of off-responses were found; a transient off-depolarization, a rebound-type off-depolarization and a transient off-hyperpolarization. The time to peak and duration of off-responses were in the order of rebound type-off-depolarization > transient off-depolarization > transient off-hyperpolarization. The reversal potential for the rebound-type off-depolarization existed in more positive level than the resting potential. The reversal potential for the transient off-depolarization was around 0 mV, and that for the transient off-hyperpolarization was -58 mV. These three off-responses in frog taste cells may be initiated by an increase in permeability of the apical receptive membrane to Na+, K+ and CI-. A kind of principal ion is dependent on off-response types.

Animals↗