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Biomedical subjects

K Okazaki

Publications and source records attributed to K Okazaki.

At least 325 records · Page 18Linked to original sources

Structure-activity relationships of cadeguomycin analogs.

The relationship between the activity and the chemical structure of cadeguomycin (CDM, 7-carboxy-7-deazaguanosine) was studied with six analogs of CDM. Both activities of CDM, enhancing the incorporation of [3H]thymidine in K562 cells and potentiating the cytotoxicity of cytosine arabinoside for K562 cells, were significantly augmented by the replacement of the 7-carboxyl group with cyano (CDM-CN) or formyl (CDM-CHO), but they were not changed by the replacement with methyl. The activities were almost completely diminished by the replacement of ribose with arabinose, but the simultaneous replacement of carboxyl and ribose with formyl and arabinose showed higher activities than those of CDM. The replacement of 7-carboxy-7-deazaguanine with 7-carboxy-7-deazainosine markedly weakened the activity. CDM-CN and CDM-CHO at 0.2 micrograms/ml significantly potentiated the activity of cytosine arabinoside against MOLT-3 cells but CDM at 1 micrograms/ml did not. These results indicate that the ribose and guanine moieties in the CDM molecule are very important for its activity. Also replacing the carboxyl group at the C-7 position with cyano or formyl group is a useful way to strengthen the CDM activity. These compounds would effectively potentiate cytosine arabinoside against various kinds of tumor cells which CDM could not do.

Anti-Bacterial Agents↗

[Clinical significance of serum dipeptidyl aminopeptidase IV in rats with adjuvant arthritis].

Serum dipeptidyl aminopeptidase IV (DAP IV) activity in rats with adjuvant arthritis (AA) were studied. DAP IV activity was significantly low in AA rats (37.7 +/- 14.1 mU/ml, n = 15) compared with control (63.7 +/- 9.0 mU/ml, n = 8) and indomethacin-treated (IDM) AA rats (55.6 +/- 14.2 mU/ml, n = 15). In addition, serum DAP IV activity was inversely correlated with hindpaw arthritis score both in AA rats and IDM-AA rats. Among serum inflammatory index examined, acid soluble glycoprotein, sialic acid were inversely correlated and albumin was positively correlated with DAP IV activity in AA and IDM-AA rats. The role of serum DAP IV remains unknown, but, it seems possible that DAP IV might modify the clinical course of AA rats in connection with its effects on the immune regulatory system.

Animals↗

[Effect of arterial carbon dioxide tension on regional myocardial tissue oxygen tension in the dog].

We investigated the effects of arterial carbon dioxide tension on the myocardial tissue oxygen tensions of subepicardium and subendocardium in the anesthetized dogs. The study was done in fourteen open-chest mongrel dogs, weighing 13 +/- 1 kg, anesthetized with sodium pentobarbital (30 mg.kg-1 iv), and mechanically ventilated with 100% oxygen to maintain normocapnia. End tidal CO2 fraction (FECO2) was monitored continuously by capnograph. Regional myocardial tissue PO2 was measured using a monopolar polarographic needle electrode. Two pairs of combined needle sensors were carefully inserted, one in the epicardial and the other in the endocardial layer of the beating heart. Electromagnetic blood flow probe was applied on the left anterior descending artery (LAD). After a stable normocapnic ventilation, hypocapnia was induced by increasing the respiratory rate, and this mechanical hyperventilation was kept fixed throughout the experiments. To induce hypercapnia, exogenous carbon dioxide was added to the inspired gas step-wise until FECO2 reached 10%. Hypocapnic hyperventilation (PaCO2: 22 mmHg) invariably resulted in a significant reduction of coronary blood flow (LADBF) and left ventricular myocardial tissue PO2 in both epicardial and endocardial layers, while addition of carbon dioxide to the inspired gas (hypercapnic hyperventilation) reversed the change by increased LADBF and arterial PaCO2 in a dose-dependent manner. These results indicate that injudicious and severe hypocapnic hyperventilation may induce impaired myocardial tissue perfusion and oxygenation although normal cardiac output and arterial blood oxygenation are maintained.

Animals↗

High-frequency transformation method and library transducing vectors for cloning mammalian cDNAs by trans-complementation of Schizosaccharomyces pombe.

We describe a highly efficient alkali cation method and library transducing vectors for cloning mammalian cDNAs by trans-complementation of fission yeast Schizosaccharomyces pombe mutants. cDNA libraries constructed with the pcD or pcD2 vector are transduced into yeast by cotransfection with a linearized vector, which allows an enhanced homologous recombination between the yeast vector and the library plasmid leading to the efficient formation of concatemers containing pcD molecules. The transformation frequencies obtained by the method are 10(6) colonies per 10(8) cells transfected with 2 micrograms of library and 1 microgram of vector, 50-60% of which contain pcD molecules. The high-efficiency alkali cation method circumvents many of the shortcomings of the spheroplast method generally used for Schiz. pombe transfection. The vectors are maximized for the efficiency of library transduction and minimized for the rearrangements of pcD molecules during propagation in yeast. This system allows rapid screening of multi-million cDNA clone libraries for rare cDNAs in a routine scale of experiments. Using this system, various mammalian cDNAs that are extremely difficult, time-consuming, or unclonable to clone by other methods have been cloned.

Animals↗

A novel peroxisomal nonspecific lipid-transfer protein from Candida tropicalis. Gene structure, purification and possible role in beta-oxidation.

We have sequenced the nucleotides of the gene POX18 that encodes PXP-18, a major peroxisomal polypeptide inducible by oleic acid in the yeast Candida tropicalis. POX18 had a single open reading frame of 127 amino acids. Some 33% of the amino acid sequence of the predicted basic polypeptide (13,805 Da), was identical to that of the nonspecific lipid-transfer protein (sterol carrier protein 2) from rat liver. PXP-18, purified to near homogeneity from isolated peroxisomes, had an amino-terminal sequence identical to that of the predicted polypeptide except for the initiator methionine, and had nonspecific lipid-transfer activity comparable to that of its mammalian equivalents. Unexpectedly, PXP-18 lacked the cysteine residue thought to be essential for the activity of this protein in mammals. RNA blot analysis showed that the POX18 gene was expressed exclusively in cells grown on oleic acid, suggesting that PXP-18 has a role in the beta-oxidation of long-chain fatty acids. PXP-18 modulated acyl-coenzyme A oxidase activity at low pH.

Amino Acid Sequence↗

Purification of protein fatty acyltransferase and determination of its distribution and topology.

Studies reported from this laboratory have demonstrated that O-glycosidic glycoproteins of salivary, pulmonary, and gastrointestinal origin are acylated by fatty acyltransferase residing in Golgi and microsome-enriched fraction (Slomiany, A., Liau, Y.H., Takagi, A., Laszewicz, W., and Slomiany, B.L. (1984) J. Biol. Chem. 259, 13304-13308). Here we report on the successful purification of this enzyme from rough microsomal membranes of rat gastric mucosa and its identification in a number of diverse tissues and organs, such as heart, liver, pancreas, lung, kidney, salivary glands, and lymphoblasts. The enzymatic activity has been released from the stripped and salt-extracted microsomes with 0.5% Triton X-100 and recovered from 100,000 x g supernatant by affinity chromatography on Cibacron blue F3GA column. The retained fatty acyltransferase protein was selectively displaced from the column with 50 microM palmitoyl-CoA. On nonreducing polyacrylamide gel electrophoresis, the enzymatic activity was associated with a 234-kDa complex, and on sodium dodecyl sulfate polyacrylamide gel electrophoresis, the complex afforded 65- and 67-kDa protein bands. Incubation of microsomes with trypsin prior to enzyme extraction resulted in a 50% inactivation of the fatty acyltransferase and generation of 53- and 55-kDa protein bands, which also had affinity to Cibacron blue F3GA and were displaced from the column together with the active (intact) enzyme. We suggest that the fatty acyltransferase is an integral rough microsomal protein partially exposed to cytosol, which catalyzes the fatty acyl-CoA-protein reaction on the cytosolic site of the rough endoplasmic reticulum and that this enzyme is responsible for processing of the group of protein which are entering rough endoplasmic reticulum-Golgi secretory pathway.

Acyl Coenzyme A↗

An evaluation of an in vivo local sound speed estimation technique by the crossed beam method.

An in vivo local sound speed estimation technique, using the crossed beam method, has been proposed and its applicability was evaluated. At first, the potential of this technique was studied by a mapping simulation using the ray tracing technique followed by an experiment with a cylindrical agar phantom. The simulation result showed that an exact measurement of local sound speed values was difficult, but the sound speed information for the local region (its relative magnitude to the surrounding medium) was emphasized as a refraction mapping pattern. The experimental results agreed well with the calculation results. Furthermore, a clinical application was performed, using the clinical system (modified electronic linear scanner), on two liver tumor patients.

Acoustics↗

Potent anticonflict activity and lessening of memory impairment with a series of novel [1]benzothieno[2,3-c]pyridines and 1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridines.

[1]Benzothieno[2,3-c]pyridines (10a-c, 11, 12a-t, and 13a,b) and 1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridines (3a-c, 7, 8a-c, and 9) were synthesized. The compounds are bioisosteres of beta-carbolines and 1,2,3,4-tetrahydro-beta-carbolines where the indole nitrogen is replaced by sulfur. Their pharmacological activity was evaluated in a water lick conflict test in rats and a passive avoidance test in mice. In the 1,2,3,4-tetrahydro[1]benzothieno[2,3-c]pyridine series, the presence of ethyl ester (3b) or cyclohexyl carboxamide (7) groups at C-3 conferred good anticonflict activity and lessening of memory impairment, while N-acylation of 3b abolished activity. In the [1]benzothieno(2,3-c]pyridine series, the aminoethyl carboxamide (12a) group at C-3 also conferred activity, but other amides studied were not active. The most potent compounds (3b, 7, and 12a) were also administered orally and had potent anticonflict and antiscopolamine amnesia-reversal activity. These compounds did not bind to the BZP receptor in spite of having structures similar to those of beta-carbolines. Compound 7 bound strongly to 5-HT1A receptors and would be expected to be a novel anxiolytic.

Animals↗

Analysis of properties of monoclonal antibodies to transmissible gastroenteritis virus using TO-163 strain.

Nineteen monoclonal antibodies (MAbs), reactive in enzyme-linked immunosorbent assay (ELISA), with porcine transmissible gastroenteritis (TGE) virus TO-163 were obtained. Of these MAbs, 5 showed neutralizing (NT) activity (x 3,200 to 25,600) against TO-163. One of the MAbs which had NT activity showed hemagglutination inhibition activity (x 5,120) too. 14 hybridomas of polypeptide specificity against TO-163 strain were developed from which 11, 2, and 1 were specific for protein E2, N, and E1, respectively. Immunofluorescence staining patterns in TGE virus-infected cells reacted with MAbs were divided into three groups (types I, II and III). The fluorescence staining of E2 specific MAbs having NT activity were limited to the perinuclear area. All MAbs having NT activity showed the same fluorescence staining pattern.

Animals↗

Participation of phosphoinositides in gastric mucosal protection by colloidal bismuth subcitrate against ethanol-induced injury.

The mechanism of gastric mucosal protection by an antiulcer agent, colloidal bismuth subcitrate (CBS), against ethanol-induced injury was investigated using in vivo and in vitro systems. The experiments in vivo were conducted with groups of rats with and without indomethacin pretreatment, and the animals received either a dose of CBS (100 mg/kg) or a vehicle (saline), followed 30 min later by ethanol. In the in vitro studies, gastric mucosa segments were cultured in the presence of CBS, ethanol, or both. The results of in vivo experiments revealed that in the absence of CBS, ethanol caused extensive gastric hemorrhagic lesions which were significantly reduced following CBS pretreatment and this effect of CBS was not prevented by indomethacin. The data obtained with gastric mucosal culture established that in comparison to the controls, ethanol caused a 27% decrease in mucin synthesis, while mucin synthesis in the presence of CBS increased by 48%. The increase in mucin synthesis evoked by CBS was accompanied by the enhanced metabolism of mucosal phosphoinositides, as reflected by a decrease in PI (15%) and PIP2 (30%), and an increase in IP1 (26%) and IP3 (67%). In contrast, ethanol, which exhibited detrimental effect on mucin synthesis, caused a decrease in PIP (35%), IP2 (47%) and IP3 (38%), and an increase in PIP2 (80%), and IP1 (51%). However, when the mucosal culture was carried out in the presence of both CBS and ethanol, the detrimental changes evoked by ethanol on mucin synthesis were prevented, and the phosphoinositide and inositide phosphate distribution patterns were quite similar to those in the mucosa cultured in the presence of CBS only.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Hyperammonemia in multiple myeloma.

Two patients with multiple myeloma who appeared to be producing ammonia are reported. Both patients showed hyperammonemia and amino acid disturbances, such as a low Fischer ratio. One patient had Bence Jones protein (lambda) type myeloma and became comatose, but the hyperammonemia and disturbance of consciousness were improved by chemotherapy for the myeloma. The other patient had IgA kappa type myeloma and somnolence and died of malignant pleurisy despite intensive chemotherapy. Autopsy showed widespread multiple myeloma and an almost normal liver. Ammonia levels in the supernatant of cultured myeloma cells from the patient's pleural effusion increased almost linearly from the time of cell seeding. These observations showed that ammonia was produced at a high level by these human myeloma cells. We also found that one of the common myeloma cell lines, RPMI 8226, could produce ammonia as well.

Amino Acids↗

Release characteristics of cisplatin chitosan microspheres and effect of containing chitin.

To increase cisplatin (CDDP) content, to suppress burst effect during the initial phase of drug release, and to improve the capacity of the system for sustained release, we prepared various types of CDDP chitosan microspheres incorporating chitin and investigated the content of CDDP and its in vitro release kinetics from these microspheres. The results of this study showed that the CDDP content increased with increasing chitosan concentration and that the incorporation of chitin in the carrier matrix produced a more pronounced increase in drug content. The addition of chitin also led to inhibition of the initial burst effect. The rate of CDDP release reduced with increasing concentration of chitosan: that is, the 50% CDDP release time was about 0.5 h with the microspheres prepared with 1.0% of chitosan and about 4.5 h with those prepared with 5.0% of chitosan, indicating about nine-fold prolongation. The addition of chitin further resulted in retardation of the rate of CDDP release. Meanwhile, our chitosan microspheres were shown to undergo enzymatic degradation by lysozymes.

Chitin↗

The multiplication of transmissible gastroenteritis viruses in several cell lines originated from porcine kidney and effects of trypsin on the growth of the viruses.

Plaque formation, replication and related cytopathic function of 9 strains of transmissible gastroenteritis (TGE) virus were examined in primary cells and cell lines such as CPK, IB-RS-2, ESK, and PK-15 originated from porcine kidney and the effects of trypsin on the replication of TGE virus were examined in CPK cells. All strains produced a cytopathic effect and grew well in CPK cells as well as in primary porcine kidney cells. The effect of trypsin on the plaque formation was different from strains. The number of plaques produced by strains TO-163, Ukiha and Niigata increased from 2.6 to 3.52 times when trypsin was present in the medium during incubation at 37 degrees C for 1 hr after adsorption of the virus at 4 degrees C for 2 hr. The plaque sizes of TO-163, h-5, Ukiha and Niigata became larger from 1.4 to 1.7 times, when trypsin was present in the agar MEM overlay.

Cell Line↗

Relation of serological- and CPE- classification of porcine enteroviruses to the classification by immunoperoxidase (IP) staining, and observation of CPE by IP staining method.

Characteristics of CPE produced by porcine enteroviruses (PEV) were examined by Immunoperoxidase (IP) staining method. Viral antigens were detected earlier than appearance of CPE. Distinctive characteristics of the three CPE types were clearly showed by the method. In cross reactions by IP staining, the titers of the staining were high (1:6,400 to 1:25,600), even though neutralizing titers of PEV with CPE II or III were low (1:200 to 1:400). The very close relationship was detected between PEV with the same CPE type, but the very low relationships were detected between PEV with the different CPE type. The relationships in CPE I group were various. The results by IP staining were more relative to CPE type than the serotype. Thus, IP staining is one method to classify PEV clearly.

Animals↗