Biomedical subjects
Publications and source records attributed to I Kato.
Aureobasidins A to R were isolated from the fermentation broth of Aureobasidium pullulans R106. Aureobasidins are cyclic depsipeptide antibiotics with MW's ranging from 1.070 to 1,148. Aureobasidins showed high in vitro antifungal activity against Candida albicans.
Aureobasidin A, a new antifungal antibiotic, was isolated from the culture medium of Aureobasidium pullulans R106. Aureobasidin A was a cyclic depsipeptide consisting of eight alpha-amino acid units and one hydroxy acid unit. The structures of the units were found by acid hydrolysis of the antibiotic to be 2(R)-hydroxy-3(R)-methylpentanoic acid, beta-hydroxy-N-methyl-L-valine, N-methyl-L-valine, L-proline, allo-L-isoleucine, N-methyl-L-phenylalanine, L-leucine, and L-phenyl-alanine. The sequence of the units was identified by NMR and FAB-MS of the products from the alkaline hydrolysis of aureobasidin A.
beta-N-Acetylhexosaminidase was produced by Trichoderma harzianum cultivated with chitin as the growth substrate. The enzyme was purified 13.2-fold to homogeneity by ultrafiltration and sequential chromatography on SP-Toyopearl and Sephacryl S-200. The molecular weight of the enzyme was estimated to be about 150,000 by gel filtration. The pH and temperature optima were 4.0-5.5 and 50 degrees C, respectively. The enzyme hydrolyzed N-acetylchitooligosaccharides at the non-reducing ends to release GlcNAc monomer. The enzyme showed a strict substrate specificity to the sugar chains in complex carbohydrates, hydrolyzing only the linkage of GlcNAc beta 1-3Gal, but not hydrolyzing the other linkages such as GalNAc beta 1-3Gal and GlcNAc beta 1-2Man.
We found that urinary fibronectin (UFN) in cancer patients was almost all fragmented and consisted mainly of the cell-binding domain. We developed a two-site immunoenzymometric assay for UFN, using two monoclonal antibodies that both recognize this domain of fibronectin. The amount of UFN was expressed as arbitrary units per milligram of creatinine. Some 2% of the 623 healthy subjects had UFN above the clinical cutoff point (200 arb. units/mg creatinine), as did 14% of the 271 patients with nonmalignant diseases. In contrast, concentrations of UFN exceeded the cutoff point in 59% of the 589 patients with cancer. In 37 patients with gastrointestinal cancer tested for UFN and for one or more of three established serum tumor markers, UFN was found in 25, significantly more often than the other markers. These results indicated that UFN is a marker that may be helpful in evaluating many kinds of cancer.
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The primary structure of the N-linked sugar chains of glucose oxidase from Aspergillus niger was investigated. These sugar chains were released from the polypeptide backbone by hydrazinolysis, and the reducing ends of the sugar chains were pyridylaminated. HPLC of the pyridylamino sugar chains with an amide-silica column showed at least seven sugar chain peaks. Chemical and exoglycosidase digestion and 400 lMHz H-NMR studies of the sugar chains of lower molecular weight showed that these were novel oligomannose-type sugar chains, (Man)5-7 (GlcNAc)2, with the structure: +/- Man alpha 1----3Man alpha 1----3(Man alpha 1----6)Man alpha 1----6(+/- Man alpha 1----3Man alpha 1---3)Man )Man beta 1----4GlcNAc beta 1----4GlcNAc.
Endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae has transglycosylation activity. Treatment of (Man)6(GlcNAc)2Asn with the enzyme in the presence of free N-acetylglucosamine gave a mixture of (Man)6GlcNAc and (Man)6GlcNAc beta 1----4GlcNAc mixture. N-Acetylglucosamine at the reducing end of the latter sugar chain was found by HPLC of the carbohydrate composition and of an exoglycosidase digest of the pyridylamino derivative of the reducing-end residue, and by 400 MHz 1H-NMR spectroscopy.
The transglycosylation activity of endo-beta-N-acetylglucosaminidase from Arthrobacter protophormiae was used for the enzymatic synthesis of novel oligosaccharides. When (Man)6(GlcNAc)2Asn was used as a substrate for the transglycosylation, (Man)6GlcNAc-Glc, (Man)6GlcNAc-Man, (Man)6GlcNAc-chitobiose, and (Man)6GlcNAc-gentiobiose were synthesized. Their structures were identified by HPLC, ion spray mass spectrometry, and digestion with glycosidases. Endo-beta-N-acetylglucosaminidases hydrolyzed the pyridylamino derivatives of these oligosaccharides.
We analyzed various synthetic oligonucleotides with the use of ion-spray mass spectrometer. The most suitable conditions were investigated for analyzing oligonucleotides with molecular weights ranging from 3000 to 15000. We have found that the pH of the solvent was critical to reduce the formation of adduct ions in the mass spectra. Tandem mass spectrometry was also used to study the sequences.
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We analyzed correlation between postoperative pulmonary complications and pre-operative pulmonary functions. In patients with severely disturbed respiratory functions; i.e. % VC of under 30% or % FEV1 of under 30%, for the past 6 years. Pulmonary complications developed in 6 of the 18 patients studied (33.3%). Of the 9 patients with preoperative PaO2 of under 70 mmHg, pulmonary complications developed in 6 patients (66.7%). Of the 7 patients with preoperative PaCO2 over 50 mmHg, pulmonary complications developed in 5 patients (71.4%). We found that postoperative pulmonary complications correlate well with preoperative PaO2 and PaCO2, in patients with severely disturbed respiratory functions.
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The mechanism of the vasodilator effect of pinacidil was examined. Pinacidil (0.1-100 microM) inhibited the increases in cytosolic Ca2+ ([Ca2+]i) and muscle tension due to norepinephrine in rat aorta. In contrast, a Ca2+ channel blocker, verapamil, inhibited the norepinephrine-stimulated [Ca2+]i more strongly than the contraction. Higher concentrations of pinacidil (3-100 microM) inhibited the verapamil-insensitive portion of the contraction and [Ca2+]i. An inhibitor of ATP-sensitive K+ channels, glibenclamide, antagonized the inhibitory effect of low concentrations (less than or equal to 10 microM) of pinacidol. Pinacidil did not change the contraction induced by Ca2+ in vascular smooth muscle permeabilized with Staphylococcus aureus alpha-toxin. Norepinephrine (in the presence of GTP), 12-deoxyphorbol 13-isobutyrate (in the absence of GTP), and treatment with GTP gamma S potentiated the contraction of permeabilized smooth muscle induced by the addition of Ca2+. Pinacidil (100 microM) inhibited the potentiation due to GTP gamma S or norepinephrine but not to phorbol ester. These results suggest that pinacidil has dual effects on vascular smooth muscle contraction. At lower concentrations (greater than 0.1 microM), it decreases [Ca2+]i, possibly by activating ATP-sensitive K+ channels. At higher concentrations (greater than 3 microM), it may additionally inhibit the receptor-mediated, GTP-binding protein-coupled phosphatidyl inositol turnover.
By expressing truncated rat pituitary 'peptidylglycine alpha-amidating enzyme' cDNAs in COS-7 cells, we found that the two reactions concerned in peptide carboxyl-terminal amidation, namely the peptidylglycine alpha-hydroxylation reaction and the peptidyl-hydroxyglycine amidation reaction, were catalyzed by 37- and 53-K proteins, which were derived from the 5'- and 3'-coding sequences, respectively. The full-length cDNA directed the expression of both the 37- and 53-K enzymes, and in the combined presence of the two enzymes the full conversion of a glycine-extended peptide into the amidated product was achieved. These results indicated that two enzymes concerned in peptide hormone alpha-amidation are generated from a common precursor protein encoded by a single mRNA.
We conducted a comparative case-control analysis of stomach cancer and atrophic gastritis involving 427 cases with stomach cancer, 1414 cases with atrophic gastritis, and 3014 control subjects based on a questionnaire survey conducted for the subjects who received gastroscopic examination at Aichi Cancer Center Hospital from April 1985 to March 1989. The risk of atrophic gastritis in both males and females was not associated with any environmental factors. The risk of stomach cancer compared with the control subjects was positively associated with an intake of salted fish guts or cod roe [relative risk (RR) = 1.52, 95% confidence interval (CI) = 1.08-2.15] and smoking (RR for 20 or more cigarettes per day = 2.84; 95% CI = 1.79-4.51) and inversely associated with Western-style breakfast (RR = 0.68; 95% CI = 0.48-0.96) in males. Additionally, the risk of stomach cancer was inversely associated with a daily intake of raw vegetables (RR = 0.56; 95% CI = 0.34-0.94) in males when compared with the patients with atrophic gastritis as controls. Several environmental factors, such as intake of green-yellow vegetables, fruit, and meat, and a family history of stomach cancer, were only associated with intestinal types of cancer in females, whereas a clear difference between diffuse and intestinal types was not observed in males. The results of the present study suggest that risk factors for stomach cancer may be different from those for premalignant lesions.
A type II restriction endonuclease designated Sse8387I was partially purified from Streptomyces sp. 8387. This enzyme cleaved adenovirus 2 DNA at three sites, lambda phage DNA at five sites, and pUC18 and M13mp18 RF DNA at one site each, but did not cleave the DNAs from pBR322, SV40, or phi X174. Sse8387I recognized the octanucleotide sequence 5'-CCTGCA decreases GG-3', cleaving where shown by the arrow. Sse8387I is the first restriction endonuclease to be reported that recognizes an octanucleotide sequence consisting of all four nucleotides, G, A, T, and C. The frequency of occurrence of Sse8387I sites within sequenced regions of primate genomes was 2.4 times that of NotI sites.
Incubation of membranes of human promyelocytic leukemia HL-60 cells with [32P]NAD led to ADP-ribosylation of several proteins including a 38 kDa protein by endogenous ADP-ribosyltransferases. The ADP-ribosylation of the 38 kDa protein was distinctly different from others on the basis of pH dependency and heat stability at 50 degrees C, suggesting that there are at least two endogenous ADP-ribosyltransferases. It was enhanced by CTP, but not affected by ATP, GTP and UTP, whereas it was inhibited by GTP gamma S. [alpha-32P]CTP bound to the 38 kDa protein immobilized on a nitrocellulose sheet, indicating that the 38 kDa protein which bound CTP is strongly ADP-ribosylated by an endogenous ADP-ribosyltransferase.