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Biomedical subjects

S Oka

Publications and source records attributed to S Oka.

At least 415 records · Page 23Linked to original sources
PubMed1988

[Hormone independent murine carcinoma BX-1 spontaneously arising from nude mouse bearing Br-10, a hormone dependent human breast carcinoma strain].

BX-1, an adenocarcinoma spontaneously arising from nude mouse bearing Br-10, a human breast carcinoma strain was characterized. And the purification of a hormone independent murine carcinoma strain, BX-1 was found in August 1986 in three institutes where a hormone dependent transplantable human breast carcinoma cell line Br-10 has been serially passaged. The histological features of BX-1 were different from any other strains which were maintained in these three institutes. Estrogen receptor of BX-1 was negative and no estrogen dependency was observed while Br-10 was the receptor positive and the growth of Br-10 was dependent on estrogen. Although the graft of BX-1 into the thymus intact littermates was rejected, the chromosomal analysis revealed only murine chromosomes for BX-1, while both of human and murine chromosomes were detected in Br-10 tumor. By incubating Br-10 tumor in untreated female nude mice for 2 months and stimulating the growth of the tumor by exogenous estradiol, the purification of Br-10 from BX-1 could be achieved. Whereas the stability of human tumor xenografts in nude mice is confirmed, the spontaneously arising murine tumor from nude mice bearing human tumor xenografts should be considered for the experiments.

Adenocarcinoma↗
PubMed1987

An epitope residing in carbohydrate chains of a sea squirt antigen termed Gi-rep.

O-Glycosidically linked oligosaccharides (Gp-1 beta-b) were liberated from a large size glycopeptide (GP) fraction (Gp-1) in a Pronase digest of a sea squirt antigen termed Gi-rep by the treatment with 0.1 N NaOH per 1 mol/L of NaBH4. Gp-1 beta-b as well as Gp-1 and the intact antigen was capable of inducing a remarkable erythema in the skin of patients with asthma with sea squirt allergy at its concentration of 10 micrograms/ml. N-Glycoside GP fractions (Gp-1 beta-a and Gp-2 beta) having the allergenic activity were also prepared as alkali-resistant GPs from Gp-1 and the other relatively small size GP fraction (Gp-2) of the Pronase digest, respectively, after the alkali treatment. Chemically, the three allergenically active preparations were rich in galactosamine, glucosamine, and fucose in common, although the N-linked carbohydrates were much larger in size than O-linked carbohydrates. Accordingly, it has been expected that the epitope of the sea squirt antigen corresponds to certain oligosaccharide units residing in both of the O- and N-linked carbohydrate chains of the antigen. This suggestion was consistent with the observation that the allergenic activity of Gi-rep was significantly unstable to the periodate oxidation but substantially stable not only to acid, alkali, and heat treatments but also to the enzymatic proteolysis with Pronase E.

Animals↗
PubMed1987

Primary structure of rat liver mannan-binding protein deduced from its cDNA sequence.

cDNA clones encoding rat liver mannan-binding protein (MBP), a lectin specific for mannose and N-acetylglucosamine, were isolated from a rat liver cDNA library carried in lambda gt 11, by screening with affinity purified polyclonal rabbit anti-rat liver MBP antibodies. The nucleotide sequence of the cDNA determined by the dideoxy method revealed the complete amino acid sequence of the MBP (226 residues). The NH2-terminal residue of the MBP, glutamic acid, was preceded by a predominantly hydrophobic stretch of 18 amino acids, which was assumed to be a signal peptide. Near the NH2-terminal, there was a collagen-like domain, which consisted of 19 repeats of the sequence Gly-X-Y. Here, X and Y were frequently proline and lysine. Three proline and lysine residues were hydroxylated, and one of the latter appeared to link to galactose. Computer analysis of several lectins for sequence homology suggested that the COOH-terminal quarter of the MBP is associated with the calcium binding as well as carbohydrate recognition.

Amino Acid Sequence↗
PubMed1987

Erythrocyte sedimentation rate. I. Volume fraction dependence in saline solution.

We have measured volume fraction dependence of the sedimentation curve of swine erythrocytes in a physiological saline solution at 10 degrees C, 20 degrees C, 30 degrees C and 40 degrees C. The sedimentation curves were found to consist of initial constant velocity region and final plateau region at the lower temperatures of 10 degrees C and 20 degrees C, while modified S-shaped curves were observed at the higher temperatures of 30 degrees C and 40 degrees C. The volume fraction dependence of the initial slope v of the sedimentation curve was fitted well to the following exponential type equation at all the temperatures: v = vs,exp (1 - H)exp[-(BH + CH2)] where vs,exp is the velocity in infinite dilution corresponding to the Stokes velocity and H is the volume fraction of erythrocytes. The volume fraction dependence of the relative velocity v/vs,exp was in close agreement with a semi-empirical equation derived for slurrys in the field of chemical engineering at the lower temperatures, while a small deviation between the observed and calculated curves was found at the higher temperatures. The volume fraction dependence of v at 20 degrees C was also analyzed on a theory recently developed by Oka. The explicit functional form of the medium up-flow factor phi (H) and the deformability factor f in the theory were determined using the experimental data.

Animals↗
PubMed1987

Optimality principle in vascular bifurcation.

The optimal geometry of the vascular bifurcation is interpreted on the basis of the principle of minimum work. We consider the energy expenditure due to the viscosity of blood, and that for maintaining the metabolic states of the blood cells and of the vessel wall. It is shown that the optimal radii of the stem and branch vessels and the optimal branching angle are related to two parameters which represent the morphologic and metabolic states of the blood and the vessel wall. In the special case of symmetrical bifurcation, it was found that as the metabolic demand of the vessel wall becomes more apparent when compared with that of the blood, the branch radius relative to that of the stem takes values of from 0.794 down to 0.758 minimally, and the angle from 37.5 degrees up to 48.7 degrees maximally with respect to the direction of the stem.

Blood Vessels↗
PubMed1987

[5-FU concentration in tumor tissue and the antitumor effect in patients with gastric cancer after oral administration of UFT].

Serum and tumor tissue concentration of FT, 5-FU and uracil were measured in 23 patients with gastric cancer who were administered UFT preoperatively. The degeneration of cancer cells was evaluated histologically and the correlation between 5-FU concentration in the tumor tissue and the antitumor effect was assessed. The average concentration of 5-FU in tumor tissue (0.122 microgram/g) was significantly higher than that in normal gastric tissues. Serum 5-FU concentration was very low, suggesting no accumulation of 5-FU in blood. A positive correlation between the concentration of 5-FU and uracil in tumor tissues was found. A 5-FU level higher than 0.05 microgram/g was frequently demonstrated in tumor tissue, resulting in moderate degeneration of cancer cells in many cases. When tumors were classified according to histological type, intratumoral 5-FU concentration was not always correlated with degeneration of cancer cells. The above results suggested that UFT was a very effective drug for stomach cancer because of high tumor affinity for 5-FU, but that it is necessary to consider the sensitivity of tumor cells to antitumor drugs in order to obtain an excellent antitumor effect.

Administration, Oral↗
PubMed1987

[Antitumor activity of cisplatin and carboplatin against human tumor xenografts serially transplanted into nude mice--with special reference to gastric carcinomas].

Experimental chemotherapy with cisplatin and carboplatin was performed against nine human tumor xenografts serially transplanted into nude mice. Tumors used for the experiment were seven gastric (St-4, St-15, St-40, H-111, SC-2-JCK, SC-6-JCK and Exp-4), one breast (MX-1) and one colon (Co-4) carcinomas. Cisplatin 9 mg/kg and carboplatin 100 mg/kg were administered intraperitoneally (ip). Carboplatin 25 mg/kg was also given ip 4 times every 4 days. The efficacy rates of cisplatin and carboplatin by bolus injection were 77.8% and 66.7% respectively with no statistically significant differences. However, carboplatin was found more effective when given by bolus. The antitumor spectra of both drugs were similar. From these results, these two platinum compounds seemed to be effective against human gastric carcinomas.

Adenocarcinoma↗