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Biomedical subjects

S Hosaka

Publications and source records attributed to S Hosaka.

At least 91 records · Page 5Linked to original sources
PubMed1985

Prostaglandin E2 counteracts the inhibition by indomethacin of rat colon ornithine decarboxylase induction by deoxycholic acid.

The mechanism whereby bile acids promote colon tumor development was studied. Bile acids increase intestinal ornithine decarboxylase (ODC), an effect that is suppressed by indomethacin, an inhibitor of prostaglandin (PG) synthesis. Male Sprague-Dawley rats were pretreated with 0.002% indomethacin solution in drinking water for 3 days, then given a single intrarectal instillation of 20 mg of deoxycholate and/or 1 mg of PGE2. Four hours later, the rats were killed, and the ODC activity was measured in the mucosa of the distal large bowel. ODC was significantly lower in rats given indomethacin plus deoxycholate than in those given deoxycholate alone, but it was significantly higher in rats treated with indomethacin and PGE2 plus deoxycholate. Without deoxycholate, indomethacin plus PGE2 did not elevate ODC compared with indomethacin alone or no treatment. Indomethacin reduced the colonic mucosal PG level. Thus, PGE2 mediates the deoxycholate-induced colonic mucosal ODC activity, and overcomes the inhibition of this enzyme activity by indomethacin. It is concluded that the anti-promoting effect of indomethacin in colon carcinogenesis, previously demonstrated, may result from the indomethacin inhibition of PG synthesis.

Animals↗
PubMed1984

Complement activation by polymer binding IgG.

It was found that immobilized IgG on polymer carriers activates complement on contact with the serum. As polymers were microspherical in this study, complement fragments bound to polymers were detected by the agglutination of the polymer microspheres with the corresponding antisera or rosette formation with cells having complement receptors. Without the immobilization of IgG, polymers having amino, carboxyl, cyano or phenyl groups activated complement in the serum, while the presence of hydroxyl and carbamoyl groups in polymers did not cause complement activation. When intact IgG was bound to poly(glyceryl methacrylate) by the use of glutaraldehyde, the IgG-polymer conjugate activated complement in spite of the inertness of the polymer itself. The polymers immobilizing F(ab')2 activated complement less than the polymers immobilizing intact IgG. When dextran aldehyde prepared by periodate oxidation of dextran was used as a binder instead of glutaraldehyde, complement activation by F(ab')2-polymer conjugate was remarkably reduced, though antibody activity for binding the antigen remained. These results should be taken into consideration in the design of an immunosorption therapy.

Animals↗
PubMed1984

Separation of carcinogenic fraction of bracken fern.

Isolation of the carcinogen in the boiling water extract of bracken fern was conducted by following the active principle with a carcinogenicity bioassay. Fractionation of the bracken extract was carried out using adsorption on resin (Amberlite XAD-2 and TOYOPEARL HW-40 (c] and organic solvent extraction. A diet containing each of the fractions was given to 7 female Charles River Sprague-Dawley rats (CD rats) of 4 weeks old, except for the second fraction. All 7 rats given the last carcinogenic fraction developed mammary and intestinal tumors and 5 rats had urinary bladder tumors. Ptaquiloside (PT) which induced mammary cancer in female CD rats and rho-hydroxystyrene glycosides were isolated from this fraction.

Animals↗
PubMed1984

Induction of hepatic ornithine decarboxylase by intraperitoneal administration of caffeine in rats.

I.p. administration of caffeine led to a significant increase in hepatic ornithine decarboxylase activity in rats. The enzyme activity reached approximately 10-fold above the control level 5 h after the injection of caffeine at a dose of 150 mg/kg body weight. The high level of ornithine decarboxylase activity remained for 3 h and then decreased rapidly. The enzyme activity of the kidney, however, was not significantly enhanced by the administration of caffeine. The possible mechanism of the caffeine-mediated hepatic ornithine decarboxylase induction is discussed.

Animals↗
PubMed1984

[Body movements during sleep in Lennox syndrome].

In Lennox syndrome the brainstem which plays important roles in regulating sleep and its parameters is thought to be disturbed. In order to clarify the importance of the dysfunction of the brainstem in Lennox syndrome, polygraphic examination were studied and their findings were assessed with prognosis. 8 patients aged from 6 to 17 years were subjected to this study. They were divided into two groups according to their prognosis. Group 1 showed good prognosis. Seizures were easily controllable and have not occurred for more than 24 months. In group 2 seizures were intractable and were uncontrollable by medication. In 4 normal children ranging in age from 4 to 10 years, the same studies were performed. Recordings were performed on two consecutive nights and the second night recordings were used for analysis. Polygraph consisted of EEG from C4 and P4, bipolar EOG from electrode attached to outer canthus, surface EMG from submental muscle and 5 or 6 other muscles including trunk and limbs. Sleep stages were determined in each minute according to the standard of APSS. Body movements were classified into two types on the basis of their distribution over body parts and on duration of movements. Gross movements (GM) involved the body trunk and lasted for more than two seconds. Twitch movements (TM) were localized in one muscle on surface EMG recordings lasting less than 0.5 seconds. In normal children, the rate of GM in sleep stage 1 and REM are significantly higher than slow wave sleep. And this is the same in TM of all muscles.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1984

Suppressive effect of caffeine on the development of hepatic tumors induced by 2-acetylaminofluorene in ACI rats.

The effect of caffeine on the development of hepatic tumors induced by 2-acetylaminofluorene (2-AAF) was studied in 6-week-old male ACI rats. Rats in group 1 were fed a diet containing 0.02% 2-AAF for 18 weeks and then basal diet for 15 weeks with normal drinking water throughout. Animals in group 2 received a diet containing 0.02% 2-AAF and a solution of 0.2% caffeine as their drinking water for 18 weeks, followed by basal diet and caffeine-free water. Rats in group 3 received drinking water containing 0.2% caffeine for 18 weeks. Rats in group 4 were given a basal diet and water freely and served as controls. The experiment was terminated after 33 weeks. Both the multiplicity, i.e. the number of tumors per rat, and the size of tumors were less (P less than 0.001 in the former case, by Student's t-test) in group 2 than in group 1. Thus, the induction of tumors of the liver by 2-AAF was suppressed by the administration of caffeine.

2-Acetylaminofluorene↗
PubMed1983

Analysis of deposits on high water content contact lenses.

Deposits on soft contact lenses of high water content were investigated morphologically and chemically and compared with those on conventional soft contact lenses of poly (2-hydroxyethyl methacrylate). The material of the lenses examined in this investigation was the crosslinked copolymer of methyl methacrylate and N-vinylpyrrolidone with a water content higher than 70%. Morphologically, the deposits on the lenses with high water content were found to have no characteristics distinguishable from those on conventional lenses. By the electron microscopic observation of the cross section of a lens that had become opaque, it was confirmed that the deposit was on the lens surface and that no deposit was within the lens. Some spots on the lenses were recognized as colonies of microorganisms, but the majority of the spots had no involvement by microorganisms. Surface analysis with Fourier transform infrared spectrometer (FT-IR) confirmed that the main component of the filmy deposit was protein. Protein was detected in most of the deposits. The amino acid compositions of the proteins were found to be close to that of lysozyme. From the elemental analysis of several spots, silicon, aluminum, iron, and some other elements were detected. The structural analysis of some spots by a laser Raman microprobe (MOLE) revealed the existence of lipids. In several cases, the deposits were found to have grown around a defect of the lens surface. A mechanism for the formation of deposits is suggested.

Amino Acids↗
PubMed1983

Ocular inserts for controlled release of antibiotics.

Ocular inserts impregnated with antibiotics (erythromycin and erythromycin estolate) which have sustained release characteristics were prepared, mainly for the purpose of trachoma therapy. In vitro experiments showed that the elution rate of a drug with low solubility in water (erythromycin estolate) is constant when the water content of the hydrogel insert is more than 30%. In the case of a drug with higher solubility (erythromycin), the elution rate depends on the water content. Some in vivo experiments using rabbit eyes were also reported.

Animals↗
PubMed1983

In vivo evaluation of ocular inserts of hydrogel impregnated with antibiotics for trachoma therapy.

Sustained release of antibiotics from hydrogel matrices in the eye was studied for the purpose of developing a new method for trachoma therapy. Copolymers of N-vinylpyrrolidone were moulded into an ocular insert and impregnated with erythromycin or erythromycin estolate. The antibiotic-hydrogel inserts completely suppressed the chlamydia trachomatis infection in the owl monkey eyes. The drug elution rates were a little lower in vivo than in vitro. By comparison of the drug elution rate in the human eye with that in the owl monkey eye, similar therapeutic effect is expected in the treatment of human trachoma.

Animals↗
PubMed1983

Carcinogenicity of dextran sulfate sodium in relation to its molecular weight.

The carcinogenicity of dextran and 3 kinds of dextran sulfate sodium with different molecular weights and almost the same sulfur content were compared in ACI rats. Dextran sulfate sodium of molecular weight 54,000 showed a strong carcinogenic activity when it was given orally as 2.5% diet, whereas dextran sulfate sodium of molecular weight 520,000 and 9500 and dextran showed no significant carcinogenicity, i.e. the peak of carcinogenic activity of dextran sulfate sodium appeared at molecular weight 54,000, and dextran sulfates with larger or smaller molecular weights had no carcinogenic activity.

Adenocarcinoma↗
PubMed1983

Induction of mammary cancer in CD rats fed bracken diet.

Fifteen male and 15 female Charles River Sprague-Dawley rats (CD rats) of 6 weeks old were given a diet containing 30% bracken fronds throughout the experimental period of 260 days. Male rats fed bracken diet developed multiple ileal tumors and urinary bladder tumors with incidences of 100% and 60%, respectively. Female rats developed multiple mammary tumors with an incidence of 87% in addition to ileal and urinary bladder tumors. The earliest mammary tumor was detected on day 78, and the last on day 256. The average number of tumors per rat was 5.6. Most mammary tumors were papillary carcinomas and adenocarcinomas. No tumors were found in rats in the control group.

Adenocarcinoma↗
PubMed1983

Preparation of microspheres of poly(glycidyl methacrylate) and its derivatives as carriers for immobilized proteins.

Microspheres of poly(glycidyl methacrylate) and its derivatives have been prepared. The diameter can be varied in the range from 0.5 to 5 micron. Proteins were immobilized on the microspheres by various processes. The maximum amount of covalently immobilized gamma-globulin on the microspheres was found to be about 6 mg/m2. It was shown that dyed microspheres with a diameter of 2-4 micron are applicable to immunological agglutination tests on a microplate as carrier particles substituting for red blood cells.

Acrylates↗