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Biomedical subjects

S Okamoto

Publications and source records attributed to S Okamoto.

At least 325 records · Page 18Linked to original sources
PubMed1995

The interaction of RepC initiator with iterons in the replication of the broad host-range plasmid RSF1010.

The replication origin of the broad host-range plasmid RSF1010 contains 3.5 copies of a 20mer iteron sequence that bind specifically to the plasmid-encoded initiator, RepC. Here we demonstrated that even a single iteron was bent upon binding of RepC. Moreover, the bending angle seems to become larger along with the increment of the number of iterons. In a mutational analysis of the iteron sequence, we isolated seven kinds of base-substitution mutants of iterons, and estimated the replication activity of these mutants in vivo. We found that each of the subsections in the 20mer iteron sequence made a distinct contribution to the initiation of RSF1010 DNA replication. With the binding assay of RepC and mutated iterons in vitro, we found that the formation of a productive RepC-iteron complex was required for the initiation of plasmid DNA replication.

Bacterial Proteins↗
PubMed1995

Design of noncovalent trypsin inhibitor based on the X-ray crystal structure of the complex.

The inhibitory mechanism of trans-4-aminomethylcyclohexanecarbonyl-L-phenyl-alanine-4-carbo xymethylanilide (1), a noncovalent serine protease inhibitor synthesized based on previous structure-activity studies, was clarified based on the X-ray crystal structure of the complex (2.2 A resolution, R = 0.175), where the amino group of the aminomethylcyclohexane moiety was bifurcately hydrogen-bonded to the carboxyl oxygens of Asp 189 side group (specificity pocket), and the hydrogen bonds of the cyclohexanecarbonyl oxygen to NHs of Gly 193 and Ser 195 residues (oxyanion hole) and of Phe NH to Ser 195 O gamma atom (catalytic triad) were observed. In contrast, the Phe benzene moiety and terminal carboxymethylanilide of 1 were not well located on the electron density map, suggesting the conformational freedom of these P1' and P2' sites at the binding pocket. Based on these insights, trans-4-aminomethylcyclohexanecarbonyl-4-nitro-L-phenylalanine-4-+ ++benzoylanilide (2) was designed, in which the P1' and P2' sites were modified so as to effectively interact with the amino acid residues of trypsin binding pocket via hydrogen bonding and van der Waals interactions, respectively. Consequently, 2 showed 40 times higher inhibitory activity against trypsin than 1.

Crystallization↗
PubMed1995

Virginiae butanolide binding protein from Streptomyces virginiae. Evidence that VbrA is not the virginiae butanolide binding protein and reidentification of the true binding protein.

Virginiae butanolides (VBs) A-E are butyrolactone autoregulators that control virginiamycin production in Streptomyces virginiae. We have previously reported the purification and molecular cloning of VbrA, a putative VB binding protein (Okamoto, S., Nihira, T., Kataoka, H., Suzuki, A., and Yamada, Y. (1992) J. Biol. Chem. 267, 1093-1098). However, VbrA protein overexpressed in Escherichia coli did not show any detectable VB binding activity nor did the immunoprecipitation of native VbrA from a cell-free extract of S. virginiae cause any decrease in such activity, indicating that VbrA is not the true VB binding protein. This finding prompted us to seek the true VB binding protein by repurification. After successive purification by anion exchange, gel filtration, heparin, and hydrophobic interaction chromatography, a 26-kDa protein (p26k) was identified as the true VB binding protein. Partial amino acid sequences of p26k were determined, and the gene (barA) that encodes this protein was isolated and cloned using degenerate oligonucleotide probes. When the barA gene was expressed in Streptomyces lividans and E. coli, strong VB binding activity appeared, demonstrating unambiguously that the S. virginiae p26k protein is the true VB binding protein.

4-Butyrolactone↗
PubMed1995

Establishment of lipopolysaccharide-dependent nuclear factor kappa B activation in a cell-free system.

Nuclear factor kappa B (NF-kappa B), consisting of p50 and p65, is bound to a cytoplasmic retention protein, I kappa B, in a resting state, and the stimulation of cells with a variety of inflammatory stimuli induces the dissociation of NF-kappa B from I kappa B and the nuclear translocation of NF-kappa B, thereby activating several genes involved in inflammatory responses, such as interleukin (IL)-6, IL-8, and tumor necrosis factor alpha. In order to elucidate the precise mechanism of NF-kappa B activation, we have established lipopolysaccharide (LPS)-dependent NF-kappa B activation in a cell-free system using plasma membrane-enriched, cytosol, and nuclear fractions extracted from a human monocytic cell line, THP-1, by disruption with sonication followed by a differential centrifugation. The combination of plasma membrane-enriched fraction and cytosol was sufficient to activate NF-kappa B in a LPS/CD14-dependent manner only in the presence of ATP as judged by the binding of NF-kappa B to the IL-8 gene kappa B site on an electrophoretic mobility shift assay. LPS-dependent NF-kappa B activation was inhibited by protein kinase inhibitors, such as staurosporine, herbimycin A, tyrphostin, and genistein, but not mitogen-activated protein kinase substrate, cGMP-dependent protein kinase, cAMP-dependent protein kinase, protein kinase C, and calmodulin-dependent protein kinase II inhibitory peptides, suggesting that staurosporine-sensitive kinase(s) as well as tyrosine kinase(s) are involved in LPS-mediated NF-kappa B activation. In addition, LPS induced the phosphorylation of I kappa B-alpha, starting at 5 min after the stimulation in a cell-free system. Moreover, the phosphorylation was inhibited by herbimycin A and tyrphostin, but not staurosporine, suggesting that these protein kinase inhibitors act at distinct steps of signal transmission. Establishment of ligand-dependent activation of NF-kappa B in a cell-free system will facilitate identification of protein kinase(s) and its substrate(s) involved in LPS-mediated NF-kappa B activation.

Amino Acid Sequence↗
PubMed1995

Induction of anterior chamber-associated immune deviation with lymphoreticular allogeneic cells.

Immune privilege in the anterior chamber of the eye results in part from a selective deficit in delayed hypersensitivity that is elicited by antigenic materials placed in this unique tissue site. This stereo-typical systemic immune response (anterior chamber-associated immune deviation [ACAID]) to intraocular antigen can also be evoked in naive mice by the intravenous injection of syngeneic peritoneal exudate cells (PEC) that have been incubated overnight with a soluble antigen in the presence of supernatants of cultured iris and ciliary body (I/CB) cells or with transforming growth factor (TGF)-beta. To determine whether a similar protocol could be used to induce ACAID to transplantation antigens expressed on allogeneic PEC, we conducted experiments with allodisparate PEC donors and recipients selected to differ at loci dictating MHC and/or minor histocompatibility antigen. Recipients of I/CB supernatant-treated PEC from donors disparate for class I and/or class II antigens, as well as donors disparate only for minor H antigens, were specifically unable to display donor-specific delayed hypersensitivity, whereas recipients of PBS-treated allogeneic PEC developed intense donor-specific delayed hypersensitivity. We conclude that allogeneic PEC that have been cultured with I/CB supernatant overnight create an alloantigen-specific ACAID-inducing signal that confers ACAID on naive recipient mice.

Animals↗
PubMed1995

Down-regulation of the cyclin A promoter in differentiating human embryonal carcinoma cells is mediated by depletion of ATF-1 and ATF-2 in the complex at the ATF/CRE site.

The human embryonal carcinoma cell line NEC14 can be induced to differentiate by the addition of N,N'-hexamethylene-bis-acetamide (HMBA). After treatment with HMBA, the level of cyclin A transcript decreased steeply, reaching less than one-tenth of the original level by 48 h. The promoter elements concerned with this down-regulation were studied by using reporter genes and by analyzing DNA-protein complexes. The deletion of the sequence between -608 and -259 containing three GC boxes decreased the promoter activity to about a half, and further deletion up to -194, eliminating the ATF/CRE site, resulted in a decrease to about a tenth of the original level in undifferentiated NEC14 cells. These sequences were involved in down-regulation of the promoter activity in differentiation-induced NEC14 cells. DNA-protein complexes formed at the ATF/CRE site with extracts prepared from undifferentiated and differentiation-induced cells gave the same footprint, but showed different electrophoretic mobilities. The supershift assay with specific antibodies against ATF-1 and ATF-2 indicated that both factors were depleted in the complex after induction of NEC14 cell differentiation. Both the ATF/CRE site and GC boxes seemed to be also involved in up-regulation of the cyclin A promoter in growth-stimulated human fibroblasts at the G1/S boundary.

Acetamides↗
PubMed1995

The S-locus of Nicotiana alata: genomic organization and sequence analysis of two S-RNase alleles.

Genomic clones encoding the S2- and S6-RNases of Nicotiana alata Link and Otto, which are the allelic stylar products of the self-incompatibility (S) locus, were isolated and sequenced. Analysis of genomic DNA by pulsed-field gel electrophoresis and Southern blotting indicates the presence of only a single S-RNase gene in the N. alata genome. The sequences of the open-reading frames in the genomic and corresponding cDNA clones were identical. The organization of the genes was similar to that of other S-RNase genes from solanaceous plants. No sequence similarity was found between the DNA flanking the S2- and S6-RNase genes, despite extensive similarities between the coding regions. The DNA flanking the S6-RNase gene contained sequences that were moderately abundant in the genome. These repeat sequences are also present in other members of the Nicotianae.

Alleles↗
PubMed1995

Glaucoma triple procedure comprising trabeculotomy with a fornix-based scleral flap.

A new triple surgery procedure was applied to 20 primary open-angle glaucomatous (POAG) eyes. This technique comprises trabeculotomy with narrow (2-3 mm) fornix-based scleral flap, combined with extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (PC-IOL) implantation. As to surgical results, at two years postsurgery 53% (9/17) of the eyes were controlled under 21 mm Hg without medication, 35% (6/17) with topical medication alone. Eighteen (90%) eyes showed improved visual acuity of two or more Snellen lines. No serious postoperative complications occurred. There was no significant difference in postoperative astigmatism as compared with ordinary ECCE and PC-IOL surgery. Trabeculotomy with fornix-based scleral flap offers the advantage of simple and safe surgery when combined with ECCE and PC-IOL implantation.

Aged↗
PubMed1995

Clinicopathologic features of early rectal carcinoma and indications for endoscopic treatment.

PURPOSE: This study was undertaken to clarify the indications for endoscopic treatment. METHODS: Clinical and pathologic features of 191 lesions in 180 patients with early rectal carcinoma were examined, including 110 intramucosal carcinomas and 81 carcinomas with submucosal invasion (submucosal carcinomas). All lesions had been endoscopically or surgically resected at the National Cancer Center Hospital between 1976 and 1990. RESULTS: Metastasis to regional lymph nodes (LN metastasis) was seen in 0 percent (0/39) of intramucosal carcinomas and 9.2 percent (6/65) of submucosal carcinomas in the surgically treated patients. The incidence of LN metastasis was higher for lesions larger than 10 mm in diameter, for those showing massive submucosal invasion, and for moderately differentiated adenocarcinomas. LN metastases were associated significantly with lymphatic invasion. CONCLUSIONS: These results suggest that early rectal carcinomas should be resected surgically if they 1) show massive submucosal invasion, 2) are classified as moderately differentiated adenocarcinomas, and 3) are larger than 10 mm in diameter. In patients with both scanty submucosal invasion and features of well-differentiated adenocarcinoma or intramucosal carcinoma and if no other risk factors for LN metastasis are present, such as lymphatic invasion by the primary lesion, surveillance may suffice after endoscopic resection.

Adult↗
PubMed1995

Inversion(10)(q11q24) in a case of adult T-cell leukemia.

We report a case of adult T-cell leukemia (ATL) with complex chromosome abnormalities including an inversion (10)(q11q24) in a 64-year-old man. Although some abnormalities of chromosome 10 have been seen in ATL and other lymphoid neoplasias, inv(10)(q11q24) has previously been reported only in a case of T-cell chronic lymphocytic leukemia. Recent studies have revealed a rearrangement of a novel homeobox-containing gene called TCL-3 or HOX11 on 10q24 in T-cell acute lymphoblastic leukemia with the specific chromosome translocation t(10;14)(q24;q11), and thus the significance of 10q24 aberrations in leukemogenesis is indicated. We suggest that, despite the rarity of this anomaly, inv(10) (q11q24) may be a new chromosome inversion related to T-cell neoplasia and that the 10q24 anomaly may be an important cytogenetic clue for the elucidation of the pathogenesis of some peripheral T-cell neoplasias.

Chromosome Inversion↗
PubMed1995

Serum 7 alpha-hydroxycholesterol as a new parameter of liver function in patients with chronic liver diseases.

To examine bile acid synthesis in chronic liver diseases, serum total 7 alpha-hydroxycholesterol level was measured by gas-liquid chromatography-mass spectrometry in patients with cirrhosis (n = 23), patients with chronic hepatitis (n = 21), and control subjects (n = 18). The serum 7 alpha-hydroxycholesterol levels were significantly lower in patients with cirrhosis than the controls (78 +/- 59 pmol/mL vs. 237 +/- 97 pmol/mL; mean +/- SD). However, in patients with chronic hepatitis, the level was fully retained (262 +/- 102 pmol/mL). Serum 7 alpha-hydroxycholesterol levels of 17 patients with cirrhosis classified as Child B and C ranged from 33 to 69 pmol/mL, and all were less than the normal range (between 104 and 466 pmol/mL), however, those levels of some patients classified as Child A were within the normal range. Serum 7 alpha-hydroxycholesterol levels significantly correlated with serum albumin, cholinesterase, total bile acid, direct bilirubin, alkaline phosphatase, indocyanine green (ICG) retention rate, hepaplastin test, and lecithin-cholesterol acyltransferase activities. We conclude that bile acid synthesis is well preserved in patients with chronic hepatitis and that it is decreased in most patients with cirrhosis. Serum 7 alpha-hydroxycholesterol may be a new parameter of liver function testing to assess hepatic bile acid synthesis in patients with chronic liver diseases.

Adult↗
PubMed1995

A new self-expansive intraurethral stent using shape memory alloy: a preliminary report of its availability.

OBJECTIVES: We describe a new stent made from shape memory alloy (SMA) first developed by our collaborative group, its structure, and a simple and easy procedure for its placement and removal without the need for a monitoring system or sedation. METHODS: The stent made of SMA was placed in 5 dogs for 10 months. It was left in situ in the shape of thermal expansion while the obturator Foley catheter was removed. RESULTS: Placement and removal of the stent was very easy and quick on each occasion in all 5 dogs. No proximal or distal dislodgement was observed in 5 dogs during the indwelling period. There was no encrustation of calcification on the surface of the stent at its removal. CONCLUSIONS: These preliminary results suggest that the SMA spiral stent might be an alternative for the relief of prostatic obstruction and be well tolerated in patients with bladder outlet obstruction. The SMA spiral stent is being developed for clinical use.

Alloys↗
PubMed1995

Carcinoma of the ampulla of Vater synchronously associated with early gastric cancer--a report of two cases.

We report two cases of carcinoma of the ampulla of Vater synchronously associated with early gastric cancers. The gastric lesions were diagnosed pre-operatively in one patient and at the time of examination of the resected specimen following pancreatoduodenectomy in the other. Specific problems in the diagnosis and management of these multiple primary carcinomas are discussed. Careful evaluation of the stomach prior to the surgical treatment for ampullary carcinoma is recommended.

Aged↗