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Biomedical subjects

T Okano

Publications and source records attributed to T Okano.

At least 415 records · Page 23Linked to original sources
PubMed1986

Lack of evidence for existence of vitamin D and 25-hydroxyvitamin D sulfates in human breast and cow's milk.

The presence of water-soluble vitamin D and 25-OH-D sulfates in human breast and cow's milk was studied. We first confirmed that synthetic vitamin D2 and D3 sulfates could not be hydrolyzed by alkali but by acid. Breast or cow's milk was separated into milk whey containing water-soluble components and milk curd containing crude proteins and lipophilic components. The separated milk whey and curd were hydrolyzed by acid or alkali and each lipid extract was subjected to HPLC analysis. Neither peak due to vitamin D and 25-OH-D was observed in the chromatograms of acid- and alkali-hydrolyzed milk whey, whereas the peaks due to vitamin D3 and 25-OH-D3 were found in the chromatograms of both acid- and alkali-hydrolyzed milk curd and there was no significant difference between the respective peak heights. The eluates corresponding to the respective peaks observed on the latter's chromatograms were collected and subjected to UV, HPLC, GC-MS and GLC to identify the existence of vitamin D3 and 25-OH-D3, respectively. We concluded from these results that neither breast nor cow's milk contained water-soluble vitamin D and 25-OH-D sulfates, whereas they contained fat-soluble vitamin D3 and 25-OH-D3. The concentrations of vitamin D3 and 25-OH-D3 in breast milk were about 125 and 350 ng/liter, while those in cow's milk were about 420 and 270 ng/liter, respectively. The experiments on the transfer of 3H-D3 and 3H-25-OH-D3 perorally dosed to lactating rats into suckling pups through their milk also supported the above conclusion.

25-Hydroxyvitamin D 2↗
PubMed1985

Cimetidine transport in rat renal brush border and basolateral membrane vesicles.

The transport of cimetidine by rat renal brush border and basolateral membrane vesicles has been studied in relation to the transport system of organic cation. Cimetidine inhibited [3H]tetraethylammonium uptake by basolateral membrane vesicles in a dose dependent manner, and the degree of the inhibition was almost the same as that by unlabeled tetraethylammonium. In contrast, cimetidine inhibited the active transport of [3H]tetraethylammonium by brush border membrane vesicles more strongly than unlabeled tetraethylammonium did. In agreement with the transport mechanism of tetraethylammonium in brush border membranes, the presence of an H+ gradient ([H+]i greater than [H+]o) induced a marked stimulation of cimetidine uptake against its concentration gradient (overshoot phenomenon), and this concentrative uptake was inhibited by unlabeled tetraethylammonium. These results suggest that cimetidine can share common carrier transport systems with tetraethylammonium in renal brush border and basolateral membranes, and that cimetidine transport across brush border membranes is driven by an H+ gradient via an H+-organic cation antiport system.

Animals↗
PubMed1985

Biologic and pharmacologic effects of harringtonine on human leukemia-lymphoma cells.

Ten human leukemia-lymphoma cell lines were tested for the growth-inhibitory effects of harringtonine (HT). HT was most active against HL-60 acute promyelocytic leukemia cells and least active against DND-41 acute lymphoblastic leukemia cells, with a 70-fold differential activity. Sensitivity of the cell lines is, in decreasing order: HL-60 greater than RPMI-8402 greater than DND-39A congruent to ML-2 congruent to MOLT-3 congruent to KG-1 greater than Daudi congruent to NALL-1 greater than BALM-2 greater than DND-41. The cell lines with rapid cell growth tended to be more sensitive to HT. To further elucidate the selectivity of the differential sensitivity, uptake and release of HT were compared in HL-60 and DND-41 cells. Uptake of [3H]HT into HL-60 and DND-41 cells showed no difference; however, the binding of [3H]HT to cellular components was greater than 16-fold higher in HL-60 cells than DND-41 cells. There were also minor, but significant differences in the inhibition of [3H]leucine incorporation into proteins of these two cell lines in the presence of 1 microgram/ml HT. To test whether the biological effects of HT are related to the concentration of, or exposure time to, HT, KG-1 cells were exposed to HT for different periods of time and the growth-inhibitory effects were compared. Increasing exposure time from 1 h to 3 h resulted in a 100-fold decrease in concentration X exposure time (c X t) at ID50; from 3 h to 6 h, in a 20-fold decrease at ID70; and from 6 h to 24 h, in a 16-fold decrease at ID90. HT was not inactivated by cells up to 24 h. These results indicate that (a) the sensitivity of different cell lines to HT may be related to the degree of HT binding; and (b) the effects of HT are more dependent on exposure time than concentration. Continuous infusion is thus rational for clinical trials of this drug, and the degree of HT binding to leukemic cells may be predictive of clinical response.

Alkaloids↗
PubMed1985

Diagnostic accuracy on detection of proximal enamel lesions in nonscreen radiographic performance.

The effect of differences in image contrast and mean density associated with Kodak Ektaspeed and Ultraspeed films was examined in association with systematic variations in exposure geometry and beam characteristics. Performance was expressed in terms of diagnostic accuracy obtainable by eight dentists who attempted to detect a known distribution of induced proximal enamel lesions in a radiographic phantom. Differences associated with the two types of film and x-ray beam quality were found to have small but statistically significant effects on diagnostic performance. The other factors of film density and projection geometry influenced diagnostic accuracy much more. The largest source of variation was observed among the individual dentists serving as observers.

Dental Caries↗
PubMed1985

Reversibility of granulocyte adhesion using polyamine-grafted nylon-6 as a new column substrate for granulocyte separation.

Reversibility of leucocytes adhered onto the surface of polyamine-grafted nylon-6 was investigated to estimate its feasibility as a new column substrate for granulocyte separation from whole blood. Polyamine-grafted nylon-6 was synthesized by a radical polymerization of 2-diethylaminoethyl methacrylate monomer onto nylon-6. The surfaces of these graft copolymers were found to show a microphase-separated structure composed of island-like phases of cationic polyamine and continuous phases of nonionic nylon-6. Interaction between leucocytes and these copolymer surfaces was studied by passing rabbit heparinized blood through a column packed with glass beads precoated with these copolymers. Columns of these copolymers showed a selective adhesion of granulocytes among leucocyte populations. Also, the adhering granulocytes were able to be recovered from the column by a gentle elution procedure. From these results, it was concluded that polyamine-grafted nylon-6 having a microphase-separated structure is suitable for use as a column substrate in granulocyte separation from whole blood.

Animals↗
PubMed1985

H+ gradient-dependent transport of aminocephalosporins in rat renal brush border membrane vesicles: role of H+/organic cation antiport system.

The transport of aminocephalosporin antibiotics such as cephalexin, zwitterion, by rat renal brush border membrane vesicles has been studied in relation to the transport system of organic cation. Cephalexin uptake was inhibited by organic cations such as tetraethylammonium, 1N-methylnicotinamide and choline, whereas cefazolin uptake was not. Tetraethylammonium uptake was inhibited by aminocephalosporins and stimulated by the countertransport effect of cephalexin. In agreement with the transport mechanisms of organic cation, the presence of an H+ gradient ([H+]i greater than [H+]o) induced a marked stimulation of aminocephalosporin uptake, and this uptake was inhibited by HgCl2 and tetraethylammonium. These results suggest that aminocephalosporins can share a common carrier transport system with organic cation in renal brush border membranes, and this system could be a part of the mechanisms of tubular secretion for aminocephalosporins.

Animals↗
PubMed1985

Transport of p-aminohippurate, tetraethylammonium and D-glucose in renal brush border membranes from rats with acute renal failure.

Transport of D-glucose, p-aminohippurate and tetraethylammonium has been studied using renal brush border membrane vesicles isolated from rats with uranyl nitrate-induced acute renal failure (ARF). Initial rate and overshoot magnitude of Na+ gradient-dependent D-glucose uptake were decreased in brush border membrane vesicles from ARF rats compared with normal rats, although there was no significant difference on D-glucose uptake in the presence of equilibrated Na+ between normal and ARF rats. Uptake of p-aminohippurate by membrane vesicles from ARF rats did not differ from normal membrane vesicles. Uptake of tetraethylammonium with or without an H+ gradient was decreased in membrane vesicles from ARF rats compared with normal rats. Dissipation rate of H+ gradient across brush border membranes did not differ between both groups. In vitro incubation of normal brush border membrane vesicles with uranyl nitrate caused no alteration in any substrate transport. However, enzyme activities such as (Na+ + K+)-adenosine triphosphatase in renal cortical homogenate were inhibited markedly in the presence of uranyl nitrate. These results suggest that uranyl nitrate-induced ARF caused alterations in the transport properties of renal brush border membranes and that these transport dysfunctions were not due to the direct effect of uranyl nitrate, but could be secondarily induced after the impairment of the integrity for tubular cells.

Acute Kidney Injury↗
PubMed1985

[Effect of recombinant alpha-interferon on advanced renal cell carcinoma].

The present study was undertaken to assess the efficacy of single agent chemotherapy with alpha A-interferon or alpha 2-interferon for metastatic renal cell carcinoma. alpha A and alpha 2-Interferon were administered i.m. at a primary dose of 3 X 10(6) units/day to 13 patients. Two patients (15%) showed partial response; 1 patient (8%), minor response; 5 patients (38%), no change; 6 patients (46%), progressive disease. These preliminary observations indicate that these interferons are active antitumor agents in patients with renal cell carcinoma.

Adenocarcinoma↗
PubMed1984

Carrier-mediated transport systems of tetraethylammonium in rat renal brush-border and basolateral membrane vesicles.

Transport of [3H]tetraethylammonium, an organic cation, has been studied in brush-border and basolateral membrane vesicles isolated from rat kidney cortex. Some characteristics of carrier-mediated transport for tetraethylammonium were demonstrated in brush-border and basolateral membrane vesicles; the uptake was saturable, was stimulated by the countertransport effect, and showed discontinuity in an Arrhenius plot. In brush-border membrane vesicles, the presence of an H+ gradient ( [H+]i greater than [H+]o) induced a marked stimulation of tetraethylammonium uptake against its concentration gradient (overshoot phenomenon), and this concentrative uptake was completely inhibited by HgCl2. In contrast, the uptake of tetraethylammonium by basolateral membrane vesicles was unaffected by an H+ gradient. Tetraethylammonium uptake by basolateral membrane vesicles was significantly stimulated by a valinomycin-induced inside-negative membrane potential, while no effect of membrane potential was observed in brush-border membrane vesicles. These results suggest that tetraethylammonium transport across brush-border membranes is driven by an H+ gradient via an electroneutral H+-tetraethylammonium antiport system, and that tetraethylammonium is transported across basolateral membranes via a carrier-mediated system and this process is stimulated by an inside-negative membrane potential.

Animals↗
PubMed1984

Carrier-mediated transport of cephalexin via the dipeptide transport system in rat renal brush-border membrane vesicles.

Carrier-mediated transport of aminocephalosporin antibiotics by renal brush-border membrane vesicles has been studied in relation to the transport systems for dipeptides and amino acids. Dipeptides such as L-carnosine (beta-alanyl-L-histidine) and L-phenylalanylglycine competitively inhibited the uptake of cephalexin, but amino acids did not. Cephalexin uptake was stimulated by the countertransport effect of L-carnosine in the normal and papain-treated vesicles, and by the effect of L-phenylalanylglycine only in the papain-treated vesicles. In the papain-treated vesicles, the hydrolysis of dipeptides was markedly decreased, and the specific activity for cephalexin transport was increased approx. 2-fold because of the partial removal of membrane proteins. These results suggest that carrier-mediated transport of cephalexin can be transported by the system for dipeptides in renal brush-border membranes.

Amino Acids↗