Biomedical subjects

K Ohgi

Publications and source records attributed to K Ohgi.

At least 19 recordsLinked to original sources

PubMed2002

Primary tumour resection of tongue carcinoma based on response to preoperative therapy.

The purpose of this study was to investigate the selection of resection techniques for primary lesions of advanced tongue carcinoma based on the effectiveness of our current preoperative therapy. Forty-three patients with advanced but potentially resectable squamous cell carcinoma of the tongue were included in this study. All patients were treated with preoperative concurrent chemoradiotherapy followed by conventional surgical resection. Semiserial sections of whole surgical specimen of primary lesion were evaluated histopathologically. In patients who achieved 85% and above regression, the extent of residual tumours two-dimensionally and in the deep layers was lesser, and the rate of tumour cell survival was lower, than in other patients. Furthermore, residual tumours tended to be localized to the superficial layers in the centre. These findings suggest that even in advanced tongue carcinomas it is possible to avoid extended resection and perform a less invasive surgery in which the extent of resection is reduced to preserve morphology and function in patients who achieved 65% and above regression following preoperative chemoradiotherapy.

Adult↗

PubMed2001

Ribonuclease T2.

Explore the source record for details and available documents.

Amino Acid Sequence↗

PubMed2001

Amino acid sequence of a trypsin inhibitor from a Spirometra (Spirometra erinaceieuropaei).

A trypsin inhibitor that is highly homologous with bovine pancreatic trypsin inhibitor (BPTI) was co-purified along with RNase from Spirometra (Spirometra erinaceieuropaei). The amino acid sequence of this inhibitor (SETI) and the nucleotide sequence of the cDNA encoding this protein were determined by protein chemistry and gene technology. SETI contains 68 amino acid residues and has a molecular mass of 7,798 Da. SETI has 31 amino acid residues that are identical with BPTI's sequence, including 6 half-cystine and 5 aromatic amino acid residues. The active site Lys residue in BPTI is replaced by an Arg residue in SETI. SETI is an effective inhibitor of trypsin and moderately inhibits a-chymotrypsin, but less inhibits elastase or subtilisin. SETI was expressed by E. coli containing a PelB vector carrying the SETI encoding cDNA; an expression yield of 0.68 mg/l was obtained. The phylogenetic relationship of SETI and the other BPTI-like trypsin inhibitors was analyzed using most likelihood inference methods.

Amino Acid Sequence↗

PubMed2001

Enzymatic properties of sialic acid binding lectin from Rana catesbeiana modified with a water-soluble carbodiimide in the presence of various nucleophiles.

The anti-tumor activity of sialic acid binding lectin from Rana catesbeiana (cSBL) was increased by chemical modification with a water-soluble carbodiimide (EDC) in the presence of nucleophiles such as ethylenediamine and glycine methylester. Investigations on ribonuclease (RNase) activities of the modified cSBLs were conducted to elucidate the fundamental mechanisms underlying enhancement of the anti-tumor activity conferred by these modifications. The following three characteristics were observed with modification. (i) RNase activity of the modified cSBL was enhanced towards double stranded RNA and RNA-oligo dA hybrids. The activity increase was observed even under physiologic ionic strength conditions; (ii) RNase activity of the modified cSBL towards single stranded RNA and poly U decreased, while the activity towards poly C was unaffected; (iii) the base preference of the B2 base recognition site of modified cSBL decreased for guanine. On the contrary, the preference for cytosine and adenine increased. This result may explain why the RNase activity towards poly C was not affected by EDC-modification as mentioned above.

Amphibian Proteins↗

PubMed2001

Amino acid sequence and characterization of a rice bran ribonuclease.

A base-nonspecific and acid ribonuclease (RNase Os) belonging to the RNase T2 family was purified from rice bran to a homogeneous state by SDS-PAGE. The primary structure of RNase Os was determined by protein chemistry and molecular cloning. The RNase Os was a simple protein and consisted of 205 amino acid residues. Its molecular weight was 22578 and its amino acid sequence showed that it was most similar to barley RNase among the known RNase T2 family enzymes having 157 amino acid residues identical with barley RNase. However, its N-terminus was blocked by a gamma-pyroglutamyl residue. The optimal pH of RNase Os was around 5.5. The base preference at the B1 and B2 site of RNase Os was estimated from the rates of hydrolysis of 16 dinucleoside phosphates, to be guanine as the case of RNase LE from tomato. RNase Os was successfully expressed from yeast cells using the E. coli yeast expression vector pYE-RNAP.

Amino Acid Sequence↗

PubMed2001

Effect of modification of the carboxyl groups of the sialic acid binding lectin from bullfrog (Rana catesbeiana) oocyte on anti-tumor activity.

The sialic acid binding lectin from bullfrog Rana catesbeiana oocyte (cSBL) is known to have anti-tumor activity. In order to investigate the relationship between the net charge of cSBL and its anti-tumor effect, cSBL was modified with a water-soluble carbodiimide (EDC) in the presence of three kinds of nucleophiles, taurine, glycine methylester and ethylenediamine. cSBL having four carboxyl groups was partially modified (ca. 2 residues). The anti-tumor activity of modified cSBLs was in the order of ethylenediamine-modified cSBL > glycine methylester-modified cSBL > taurine modified cSBL > or = native cSBL. The results suggested that anti-tumor activity seems to increase with the increase in positive net charge, possibly enhancing the interaction of cSBL with sialoglycoprotein on the surface of tumor cells. The ribonuclease activity of ethylenediamine-modified cSBL decreased with the progress of the reaction, but the number of internalized molecules in the tumor cell increased. Thus, for antitumor activity, a higher incorporation of cSBL with reasonable RNase activity seems to be more important than total RNase activity.

Amino Acid Sequence↗

PubMed2001

[MR hydrography of the abdomen: technical consideration of data acquisition and future prospects for clinical applications].

Recent advances in MR hydrography have enabled various clinical applications in the areas of abdominal and pelvic disorders, for example, MR cholangiopancreatography (MRCP), MR urography(MRU), and MR hydrography of the fetus. Although the two-dimensional(2D) single-slice method provides excellent information as to the global relationship between lesions and various anatomical structures, small lesions or detailed anatomical characteristics may not be visualized owing to the partial volume effect. Source images of the 2D multislice method are most suitable for the detection of small lesions and detailed evaluation of anatomical structures as "tomographic imaging", while the three-dimensional(3D) method is useful in obtaining data sets for 3D imaging. MR hydrography is a promising method for the noninvasive evaluation of various abdominal disorders, and it has the potential to play new roles in various anatomical regions. However, knowledge of the proper indications is essential for successful clinical application.

Abdomen↗

PubMed2000

Crystal structure of a plant ribonuclease, RNase LE.

Ribonuclease LE (RNase LE) from cultured tomato (Lycopersicon esculentum) cells is a member of the RNase T(2) family showing broad base specificity. The crystal structure of RNase LE has been determined at 1.65 A resolution. The structure consists of seven alpha-helices and seven beta-strands, belonging to an alpha+beta type structure. Comparison of the structure of RNase LE with that of RNase Rh, a microbial RNase belonging to the RNase T(2) family, reveals that while the overall folding topologies are similar to each other, major insertions and deletions are found at the N-terminal regions. The structural comparison, an amino acid sequence alignment of the RNase T(2) enzymes, and comparison of the disulfide-bonding pattern of these enzymes show that the structure of RNase LE shown here is the basic framework of the animal/plant subfamily of RNase T(2) enzymes (including a self-incompatibility protein called S-RNase), and the structure of RNase Rh is that of the fungal subfamily of RNase T(2) enzymes (including RNase T(2)). Subsequently, we superposed the active-site of the RNase LE with that of RNase Rh and found that (1) His39, Trp42, His92, Glu93, Lys96, and His97 of RNase LE coincided exactly with His46, Trp49, His104, Glu105, Lys108, and His109, respectively, of RNase Rh, and (2) two conserved water molecules were found at the putative P(1) sites of both enzymes. These facts suggest that plant RNase LE has a very similar hydrolysis mechanism to that of fungal RNase Rh, and almost all the RNase T(2) enzymes widely distributed in various species share a common catalytic mechanism. A cluster of hydrophobic residues was found on the active-site face of the RNase LE molecule and two large hydrophobic pockets exist. These hydrophobic pockets appear to be base binding sites mainly by hydrophobic interactions and are responsible for the base non-specificity of RNase LE.

Amino Acid Sequence↗

PubMed2000

Amino acids and peptides. LVII. Synthetic peptide with a sequence of ribonuclease from Sulfolobus solfataricus, SSR(1-62), does not function as an RNase.

The 62 residue peptide, SSR(1-62), whose sequence corresponds to that of ribonuclease (RNase) from Sulfolobus solfataricus, and its related peptides, SSR(1-22) and SSR(10-62), were chemically synthesized and their RNase activity and DNA-binding activity were examined. The RNase activity assay using yeast RNA or tRNA(fMet) as substrate showed that the synthetic peptide SSR(1-62) did not hydrolyze yeast RNA or tRNA(fMet). These data were not consistent with previous reports that both the native peptide isolated from S. solfataricus [Fusi et al. (1993) Eur. J. Biochem. 211, 305-311] and the recombinant peptide expressed in Escherichia coli [Fusi et al. (1995) Gene 154, 99-103] were able to hydrolyze tRNA(fMet). However, the synthetic SSR(1-62) exhibited DNA-binding activity. In the presence of synthetic SSR(1-62), the cleavage of DNA (plasmid pUCRh2-4) by restriction endonuclease (EcoRI) was not observed, suggesting that synthetic SSR(1-62) bound to DNA protected DNA from its enzymatic digestion. Neither SSR(1-22) nor SSR(10-62) prevented DNA from being cleaved by a restriction enzyme. These findings strongly suggest the importance of not only the N-terminal region of SSR(1-62) but also the C-terminal region for DNA-binding. Circular dichroism spectroscopy of synthetic SSR(1-62) indicated a beta-sheet conformation, in contrast with synthetic SSR(1-22), which exhibited an unordered conformation.

Amino Acid Sequence↗

PubMed2000

Primary non-Hodgkin's lymphoma of the mandible treated with radiotherapy, chemotherapy, and autologous peripheral blood stem cell transplantation.

Extranodal presentation in non-Hodgkin's lymphoma (NHL) is uncommon, and the mandible is very rarely involved. Primary NHL of the mandible, for the most part, has intermediate or high malignancy and has a much greater incidence of local recurrence compared with other sites of involvement. A 48-year-old Japanese man with NHL of the mandible received radiotherapy, followed by high-dose chemotherapy supported with peripheral blood stem cell transplantation (PBSCT). High-dose cyclophosphamide, Adriamycin, and vincristine were used for pretransplant conditioning. He achieved complete remission and has survived in continuous complete remission for more than 72 months to date. Marrow-ablative chemotherapy facilitated by PBSCT is thought to be useful as part of the primary therapy for patients with NHL who have poorer prognoses.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2000

Relationship of two ribonucleases with molecular masses of 45 kDa and 37 kDa from the culture medium of Lentinus edodes.

Lentinus edodes (shiitake) produces three base non- specific and acid ribonucleases, RNase Le2, RNase Le37 and RNase Le45. The primary structures of the former two RNases, having molecular masses about 24 and 37 kDa, respectively, have been elucidated to be members of the RNase T2 family. The latter two are excreted from mycelia into the medium. In this report, we estimated the primary structure of RNase Le45 using the following experimental evidence. (i) The partial amino acid sequence of RNase Le45 determined that up to about 60% of total protein was identical with that of RNase Le37. (ii) The amino acid composition of RNase Le45 was identical to that of RNase Le37. (iii) The elution profiles on HPLC of lysylendopeptidase and Staphylococcus aureus V8 protease digests of RCM-RNase Le45 (reduced and S-carboxymethylated RNase Le45) were very similar to those of RNase Le37, except for the absence of C-terminus peptide which contained O-glycosylated peptides. However, RNase Le45 contained about 70 residues of mannose and 4 residues of hexosamine. These values were more than twice those of RNase Le37. (iv) RNase Le45 was immunologically indistinguishable from RNase Le37. (v) After treatment with both glycosidase EndoH and alpha-mannosidase, RNases Le37 and Le45 gave complex bands by slab-gel electrophoresis. However, one of the major bands with the highest mobility from RNase Le45 and Le37 showed the molecular mass of 29 kDa in common, which is slightly larger than that of RNase Le2 containing no carbohydrate. These results indicated that RNase Le45 is an enzyme which is a heavily glycosylated species of RNase Le37.

Amino Acid Sequence↗

PubMed2000

Enzymatic properties of phenylalanine101 mutant enzyme of ribonuclease rh from Rhizopus niveus.

To investigate the role of Phe101, a component of a base recognition site (B2 site) of a base-nonspecific RNase Rh from Rhizopus niveus, we prepared several enzymes mutated at this position, F101W, F101L, F101I, F101A, F101Q, F101R, and F101K, and their enzymatic activities towards RNA, 16 dinucleoside phosphates, and 2', 3'-cyclic pyrimidine nucleotides were measured. Enzymatic activity toward RNA of F101W, F101L, and F101I were about 7, 20, and 3.8% of the native enzyme, respectively, and those of the other mutants were less than 1% of the RNase Rh. Similar results were also obtained with GpG as substrate. Thus, it was concluded that Phe101 is a very important residue as a component of the B2 site of RNase Rh, and its role could be replaced by Leu, then Trp and Ile, though in less effectively. The results suggested that some kind of interaction between B2 base and the side chain of amino acid residue at the 101th position, such as pi/pi or CH/pi interaction is very important for the enzymatic activity of RNase Rh. The mutation of Phe101 markedly affected the enzymatic activity toward dinucleoside phosphates and polymer substrates, but only moderately the rate of hydrolysis of cyclic nucleotides, indicating the presence of secondary effect of the mutation on B1 site.

Base Sequence↗

PubMed2000

Amino acid sequence of an unique ribonuclease with a C-terminus rich in O-glycosylated serine and threonine from culture medium of Lentinus edodes.

The mushroom Lentinus edodes produces three base-non-specific and acid ribonucleases, RNases Le2, Le37, and Le45. The latter two are excreted from mycelia into the medium. The primary structure of RNase Le37, which had a molecular mass of 37 kDa, was sequenced. It was a member of the RNase T2 family, as is RNase Le2. RNase Le37 was some 30 amino acid residues longer at the C-terminal end than RNase Le2. The C-terminal region of RNase LE37 was rich in O-glycosylated serine and threonine. In fungal glucoamylases and chitinases, which hydrolyze raw-starch and chitin, respectively, have structures resembling the structure of the C-terminal of RNase Le37.

Agaricales↗

PubMed2000

Amino acid sequence of a nuclease (nuclease Le1) from Lentinus edodes.

The fruit bodies of Lentinus edodes produce two acid nucleases, nucleases Le1 and Le3, both of which are thought to be candidates for the enzymes producing a tasty substance, 5'-GMP. To obtain the basic information on the mechanism of production of 5'-GMP, and structure-function relationship of these nucleases, the primary structure of nuclease Le1 was estimated by both protein chemistry and gene cloning. Nuclease Le1 is a glycoprotein and consists of 290 amino acid residues, and about 2 and 6 residues of hexosamine and neutral sugar, respectively. The nucleotide sequence of cDNA and genomic DNA encoding nuclease Le1 indicated the presence of 20 amino acid residues of a signal peptide. Nuclease Le1 has 115 and 108 residues of identical amino acid residues with nucleases P1 and S, respectively. The amino acid residues concerning the coordination with Zn2+ in nuclease P1 are all conserved in nuclease Le1. Nuclease Le1 contains 8 half-cystine residues and 4 of them are located at the same places as those of nucleases P1 and S.

Amino Acid Sequence↗

PubMed1999

Preoperative concurrent chemoradiotherapy plus radical surgery for advanced squamous cell carcinoma of the oral cavity: an analysis of long-term results.

Locoregionally advanced squamous cell carcinomas of the head and neck continue to be a major clinical problem. We demonstrated in 1996 that preoperative concurrent cisplatin- or carboplatin-based chemotherapy and radiotherapy plus radical surgery in advanced oral cancer had minimal toxicity, had high clinical tumor response rates, was well tolerated and produced impressive complete response rates and a high 5-year survival rate. The purpose of the present study was the long-term follow-up of this treatment regimen for advanced oral carcinoma. Forty-eight patients with squamous cell carcinoma of the oral cavity (including soft palate) were treated preoperatively with cisplatin- or carboplatin-based chemotherapy in combination with simultaneous irradiation to a target volume of 40 Gy, and 2-6 weeks later underwent curative surgery. All patients with advanced Stage II (n=7), Stage III (n=22) and Stage IV (n=19) were treated and followed for an average of 7.2 years (range: 61-144 months). The overall actuarial survival of all patients was 81.3% at 5 years and also at 10 years. Progression-free survival at both 5 and 10 years was 84.8% for all patients, and 85.7% for Stage II, 90.0% for Stage III, and 78.9% for Stage IV patients. Progression-free survival rates according to the histopathologic regression grade of primary tumor following preoperative chemoradiotherapy at 10 years were 40. 0% for Grade IIa, 88.9% for Grade IIb, 100% for Grade III, and 87.5% for Grade IV. Patients who achieved good responses histopathologically (Grades IIb, III, IV) had superior survival rates in comparison to patients with extensive residual tumor (Grade IIa) in surgically resected specimens (p=0.0012). A better histologic regression grade was also associated with a higher survival rate even in the long-term analysis. This treatment regimen for advanced oral cancer produced high clinical and pathologic complete response and survival rates with an acceptable acute toxicity profile and lack of late therapeutic complications. The long-term follow-up showed gratifying results even for advanced oral cancers without a substantial increase in distant metastasis and second primary malignancy.

Adult↗

PubMed1999

Amino acids and peptides. LIV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. I.

The 2-adamantyloxycarbonyl group was employed for the protection of the epsilon-amino group of Lys and the hydroxyl group of Tyr, and the 2-adamantyl ester was employed for the protection of the beta-carboxyl group of Asp in order to construct eight peptide segments as building blocks for the preparation of peptide fragments related to the sequence of Sulfolobus solifataricus Ribonuclease. The usefulness of the above protecting groups developed in our laboratory was confirmed.

Adamantane↗

PubMed1999

Amino acids and peptides. LV. Application of 2-adamantyl derivatives as protecting groups to the synthesis of peptide fragments related to Sulfolobus solifataricus ribonuclease. II.

Segment condensations were performed to construct peptide fragments related to Sulfolobus solifataricus Ribonuclease. At each condensation step, the new protecting groups were stable. The protected peptide fragments were treated with a low-high HF procedure to give the desired peptide fragments. These peptide fragments were also prepared by the solid-phase method, and the obtained peptides were compared with those obtained by the solution method. The peptide fragments obtained by the solution method were identical with those obtained by the solid-phase method on analytical HPLC, indicating that the new protecting groups could be easily removed by HF, and no racemization occurred during the synthesis of the protected peptides.

Adamantane↗

PubMed1998

Characterization and primary structure of a base non-specific and acid ribonuclease from Dictyostelium discoideum.

A base non-specific and acid RNase was isolated from cellular slime mold (Dictyostelium discoideum) cells in a homogeneous state (about 2.4 kDa) by SDS-polyacrylamide gel electrophoresis. The RNase (RNase DdI) has a pH optimum of 5.0. The amino acid sequence of RNase DdI was determined by a combination of protein chemistry, a search of Data base, Dicty cDB and further sequence analysis of cDNA from the same bank. RNase DdI consists of 198 amino acid residues, and about 13.3, 0.9, 1.2, 3.3, and 1.0 residues of mannose, xylose, glucose, GlcNAc, and GalNAc, respectively. RNase DdI has two characteristic conserved segments of the RNase T2 family, and thus belongs to the RNase T2 family. Considering the fact that most of the RNase activity of D. discoideum is present in the lysosomal fraction [Wiener and Ashworth (1970) Biochem. J. 118, 505-512], it was concluded that the lysosomal RNase in D. discoideum is a member of the RNase T2 family. The amino acid sequence of RNase DdI is highly homologous with that of Physarum polycephalum RNase (RNase Phyb), and its amino acid sequence seems to be similar to those of plant/animal type RNases, rather than fungal RNases. The location of RNase DdI in the phylogenetic tree of the RNase T2 family was estimated.

Amino Acid Sequence↗