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S Awazu

Publications and source records attributed to S Awazu.

At least 73 records · Page 4Linked to original sources
PubMed1993

Lipid peroxidation in rat liver microsomes during naproxen metabolism.

Naproxen, a non-steroidal anti-inflammatory drug, is known to be highly effective and relatively safe, but some side-effects in the liver have been reported. In the present study, the effect of naproxen metabolism on rat liver microsomes was studied by determining lipid peroxidation in terms of thiobarbituric acid reactive substances (TBA-RS), high molecular weight protein aggregates and fluorescent substances formed in the microsomal suspension containing naproxen, NADPH and MgCl2. Lipid peroxidation was found to occur at 10 mM naproxen. Production of chemiluminescence from the microsomal suspension was observed during naproxen metabolism. The time course of 6-demethyl-naproxen formation by O-demethylation of naproxen appeared to be comparable to that of the chemiluminescence production in their initial periods of production. These results suggest that the lipid peroxidation was provoked through the reactive oxygen species generated during the oxidative metabolism of naproxen.

Animals↗
PubMed1993

Comparative study of active absorption by the intestine and disposition of anomers of sugar-conjugated compounds.

Active absorption in the intestine and metabolism of the beta- and alpha-anomers of the glucoside and galactoside of p-nitrophenol (p-NP) were studied to find a more suitable prodrug for poorly absorbed drugs. The everted sac technique was used to investigate the intestinal absorption of these glycosides at 250 microM from the mucosal to the serosal side in the rat jejunum. The absorption clearance of p-nitrophenyl alpha-D-glucopyranoside (p-NP alpha glc) (0.271 +/- 0.089 microL/min/cm, mean +/- SE, N = 8) was much lower than that of p-nitrophenyl beta-D-glucopyranoside (p-NP beta glc) (4.45 +/- 0.34 microL/min/cm, mean +/- SE, N = 4) which is actively absorbed by a glucose transport carrier [Mizuma et al., Biochem Pharmacol 43: 2037-2039, 1992]. However, the major constituent appearing on the serosal side was p-NP (aglycone) after absorption of pNP alpha glc, whereas it was p-NP beta glc itself after absorption of p-NP beta glc. The total amount transported to the serosal side after 20 min of p-NP alpha glc absorption, which was similar to that of p-NP beta glc, was significantly decreased in the absence of Na+, indicating the active absorption of p-NP alpha glc by a Na(+)-dependent glucose transport carrier. Perfusion with a mucosal solution of p-NP alpha glc showed that the p-NP concentration on the serosal side (15.8 +/- 1.56 microM, mean +/- SE, N = 3) was significantly (P < 0.05) higher than that on the mucosal side (5.84 +/- 1.24 microM, mean +/- SE, N = 3) at 20 min. This indicated that the p-NP appearing on the serosal side was derived not from absorption of p-NP but from hydrolysis of p-NP alpha glc through the intestinal membrane during absorption. On the other hand, after absorption of p-nitrophenyl beta-D-galactopyranoside (p-NP beta gal), which is actively absorbed by glucose transport carrier, p-NP beta gal itself appeared mostly on the serosal side. However, p-nitrophenyl alpha-D-galactopyranoside (p-NP alpha gal) absorption, which resulted in appearance on the serosal side, was not significantly decreased in the presence of 1 mM phloridzin or in the absence of Na+, indicating that the contribution of the glucose transport carrier to p-NP alpha gal absorption was minimal. The order of the Na(+)-dependent intestinal absorption was p-NP beta glc > p-NP alpha glc > p-NP beta gal > p-NP alpha gal.

Animals↗
PubMed1993

Effect of vitamin A on methotrexate cytotoxicity in L1210 murine leukemia cells in culture.

Vitamin A (VA) protects the small intestine from methotrexate (MTX)-induced damage. However, before VA can be used as a remedy to protect cancer patients from MTX-induced damage to the intestine, it is essential to clarify whether or not it disturbs the antitumor activity of MTX. This study investigated the effect of VA on the antitumor activity of MTX in vitro in L1210 murine leukemia cells. The incorporation of [6-3H]-thymidine and [6-3H]-uridine, [5-3H]-uridine, and [4,5-3H]-leucine into DNA, RNA, and proteins, respectively, was examined to evaluate this effect. The incorporation of thymidine, the uridines, and leucine decreased dose-dependently in MTX-treated L1210 cells and profoundly in the MTX plus VA-treated L1210 cells, since VA itself had a cell-killing activity. Thus, MTX depressed the growth of L1210 cells dose-dependently and this depression was not affected by the presence of VA. The present study proved in L1210 murine leukemia cells in vitro that VA did not disturb the antitumor activity of MTX.

Animals↗
PubMed1993

Absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) from rat nasal mucosa.

Nasal absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) was examined in the rat. The relative bioavailability of rhG-CSF for subcutaneous administration was approximately 2%, as evaluated from the immunologically active rhG-CSF concentration in rat plasma and the area under the curve (AUC) of the plasma rhG-CSF concentration versus time for 8 hr. Pharmacological availability relative to subcutaneous administration was determined from the increase in total blood leukocyte numbers. The pharmacological availability was 5-10%, determined from the AUC for the increased ratio of total leukocyte numbers versus time for 48 hr; it was slightly dependent on the pH and the osmotic pressure of the dosing solution. Accordingly, the plasma concentration of rhG-CSF did not always reflect its pharmacological effects. Relative bioavailability and pharmacological availability were increased about 23 times and 3 times, respectively, by polyoxyethylene 9-lauryl ether (Laureth-9), but no increase in availability occurred with sodium glycocholate. The increase in total leukocyte numbers was maintained during multiple rhG-CSF dosing, and the addition of Laureth-9 further increased the pharmacological effects of this agent. This study indicates that nasal administration of rhG-CSF is an effective parenteral administration route.

Absorption↗
PubMed1993

Vitamin A, a useful biochemical modulator capable of preventing intestinal damage during methotrexate treatment.

The effects of vitamin A on methotrexate treatment of mice inoculated with L1210 leukaemia cells or sarcoma 180 cells were studied. The small intestine of tumour transplanted mice was severely damaged after methotrexate treatment. Coadministration of vitamin A with methotrexate protected the small intestine from methotrexate-induced damage. The protective effect of vitamin A was histologically and biochemically demonstrated. Further, coadministration of vitamin A did not inhibit in vivo antitumour activity of methotrexate. Thus, biochemical modulation used to prevent methotrexate-induced malabsorption by vitamin A coadministration will be of great use in methotrexate cancer chemotherapy.

Animals↗
PubMed1992

Evaluation of adriamycin-induced lipid peroxidation.

Lipid peroxidation is known to be a mechanism for Adriamycin-induced toxicity. In the present study, two methods which detect fluorescent substances and high molecular weight protein aggregates in peroxidized membranes were applied to Adriamycin-induced lipid peroxidation in liver microsomes. A rat liver microsomal suspension containing an NADPH-generating system was incubated with Adriamycin. Thiobarbituric acid reactive substances (TBA-RS), formed during this incubation, were transferred from the microsomes to the medium. Fluorescent substances determined by the fluorescence emitted from both the microsomes themselves and the chloroform/methanol extracts of the microsomes, were found to be formed during this incubation. High molecular weight protein aggregates determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, were also formed. Fluorescent substances and high molecular weight protein aggregates were found in microsomal membranes themselves and increased time dependently. These substances retained in membranes can be of great use to delineate the site of Adriamycin-induced lipid peroxidation in vitro and in vivo and to determine how this lipid peroxidation affects the membrane.

Animals↗
PubMed1992

Intestinal active absorption of sugar-conjugated compounds by glucose transport system: implication of improvement of poorly absorbable drugs.

The intestinal absorption of glucose- and galactose-conjugated compounds was studied in the everted sac of the rat small intestine. The absorption clearance of p-nitrophenyl beta-D-glucopyranoside (p-NPglc) at 250 microM in the mucosal side (4.45 +/- 0.34 microL/min/cm, mean +/- SE, N = 4), calculated by dividing the absorption rate by the drug concentration, was significantly decreased (0.476 +/- 0.036 microL/min/cm) in the presence of 1 mM phloridzin, an inhibitor of glucose transport, and in the absence of Na+, a cosubstrate of the glucose transport carrier (0.424 +/- 0.018 microL/min/cm). The absorption clearance of p-NPglc was decreased as its concentration increased. In the same experiment, the absorption clearance of p-nitrophenyl beta-D-galactopyranoside (1.99 +/- 0.23 microL/min/cm) was also significantly decreased in the presence of phloridzin and in the absence of Na+. However, the absorption clearance of p-nitrophenyl beta-D-mannopyranoside (0.811 +/- 0.013 microL/min/cm) was low and not significantly decreased in the presence of phloridzin (P greater than 0.1). Furthermore, the absorption clearance of beta-naphthyl beta-D-glucopyranoside and beta-naphthyl beta-D-galactopyranoside was also significantly decreased in the presence of phloridzin (P less than 0.001). These results indicated that the glucose and galactose moieties provided these compounds with a new route by way of the glucose transport carrier for intestinal absorption.

Animals↗
PubMed1992

Human urine deoxyribonuclease II (DNase II) isoenzymes: a novel immunoaffinity purification, biochemical multiplicity, genetic heterogeneity and broad distribution among tissues and body fluids.

Deoxyribonuclease II (DNase II) was purified from the urine of a 48-year-old male (a single individual) using a column chromatography series, including concanavalin A-agarose and an immunoaffinity column utilizing anti-human spleen DNase II antibody, and was then characterized. Based on the catalytic properties of the purified enzyme, we have devised a technique of isoelectric focusing by thin-layer polyacrylamide gel electrophoresis (IEF-PAGE) combined with a specific zymogram method, for investigating the possible molecular heterogeneity of human DNase II. DNase II in urine as well as the purified form was found to exist in multiple forms with different pI values separable by IEF-PAGE within a pH range of 5-7. Since sialidase treatment of the urine sample induced simplification of the isoenzyme patterns with diminishment of anodal bands, it was clear that the multiplicity of the enzyme was in part due to differences in the sialic acid content. On screening of DNase II isoenzyme patterns in urine samples from more than 200 Japanese individuals, only the common isoenzyme pattern was observed and no electrophoretic variations were detected. However, genetic studies of urinary enzyme activity and comparative studies on the activity in urine, semen and leukocytes from the same individuals suggest that the enzyme activity level of DNase II may be under genetic control. The enzyme was widely distributed in human tissues and showed high activities in secretory body fluids such as breast milk, saliva, semen and urine, and leukocyte lysates.

Body Fluids↗
PubMed1992

Fluorospectroscopic analysis of the fluorescent substances in peroxidized microsomes of rat liver.

The fluorescent substances formed in rat liver microsomes in the course of lipid peroxidation were investigated by fluorescence techniques. The fluorescence emitted from peroxidizing microsomes continuously increased as lipid peroxidation progressed, while the steady-state fluorescence anisotropy increased and then reached a plateau. A similar increase was observed in the steady-state fluorescence anisotropy of 1,6-diphenyl-1,3,5-hexatriene in peroxidizing microsomes. The fluorescence from peroxidized microsomes consisted of at least three species having short, middle or long fluorescence lifetimes. The lifetimes and relative amplitudes of fluorescence were unaffected by the extent of lipid peroxidation. Both fluorescence of the chromolipids extracted and the proteins isolated from peroxidized microsomes had the same characteristics in fluorescence lifetimes as the fluorescence from whole peroxidized microsomes. Thus, these lipids and proteins appear to be the major biological substances responsible for the fluorescence emanating from whole peroxidized microsomes. Furthermore, fluorescent substances formed in microsomes seem to increase in quantity rather than change in quality as lipid peroxidation progresses.

Animals↗
PubMed1992

Differences in the enhancing effects of sodium caprate on colonic and jejunal drug absorption.

We examined the enhancing effect of sodium caprate (C10) on the jejunal absorption of a poorly absorbed drug, cefmetazole, in rats, in comparison with its colonic absorption (Pharm. Res. 5, 341-346, 1988). Jejunal absorption was significantly enhanced by C10, but to a smaller extent than colonic absorption. Membrane perturbation, caused by the interaction between C10 and membrane proteins or lipids, was shown to increase transcellular drug permeability, as reported in the colon. Paracellular permeabilities, obtained from the permeabilities of water-soluble nonelectrolytes of various molecular weights, showed a two-phase pattern against their free diffusion coefficients, suggesting the existence of at least two pore routes similar to those in the colon. C10 increased paracellular permeability in the colon but not in the jejunum. Impedance analysis and voltage clamp technique in the jejunum showed no significant effect of C10 on paracellular permeability, such as found in the colon. Accordingly, the difference in the effects of C10 on the jejunal and colonic absorption of cefmetazole was due mainly to the difference in its effects on the paracellular pathway.

Animals↗
PubMed1992

High molecular weight protein aggregates formed in the liver of the rat following large doses of paracetamol.

Paracetamol (200 and 500 mg kg-1) was given intraperitoneally to rats pretreated with 3-methylcholanthrene for 3 days. Glutamic oxalacetic acid transaminase (GOT) activity in plasma increased in rats receiving 500 mg kg-1 paracetamol. Plasma GOT activity was low at the dose of 200 mg kg-1, but the same dose to diethyl maleate pretreated rats increased the GOT activity. High mol. wt protein aggregates were found to be formed in liver homogenates and microsomes of rats which showed high plasma GOT activity, accompanied by depletion of hepatic glutathione. The formation of protein aggregates in the liver of rats following large doses of paracetamol suggests a contribution of lipid peroxidation to paracetamol-induced hepatotoxicity.

Acetaminophen↗
PubMed1992

Species and organ differences of sulphate conjugation of p-nitrophenol in liver and platelets.

Sulphate conjugation of p-nitrophenol (p-NP) in the liver and platelet cytosol of guinea pigs, rabbits and dogs were studied. The dependency of phenol sulphotransferase (PST) activity on p-NP concentration in the liver of guinea pigs and rabbits and in the platelets of guinea pigs were similar to that reported for the liver (Mizuma et al., J. Pharmacobio-Dyn., 6, 851 (1983)) and platelets (Nakamura et al., J. Pharm. Pharmacol., 42, 207 (1990)) of rats. There was one peak of PST activity on p-NP at the concentration of 1 to 10 microM, and the PST activity was increased again with an increase of p-NP concentration above the original concentration. On the other hand, a peak in PST activity on p-NP at the concentration of 1 to 10 microM was not observed in the platelets of rabbits and dogs. These results indicated species and organ differences in PST activity on p-NP in liver and platelets. The biphasic activities of the PST and p-NP in platelets and liver of rat and guinea pig were similar to that reported in humans (Reiter et al., Naunyn-Schmiedeberg's Arch. Pharmacol., 324, 140 (1983)).

Animals↗
PubMed1992

Thermal characteristics of poly (DL-lactic acid) microspheres containing neurotensin analogue.

The thermal characteristics of poly (DL-lactic acid) (DL-PLA) microspheres containing a hexapeptide (NA: H(CH3)-Arg-Lys-Pro-Trp-tert-Leu-Leu-OEt) with neurotensin activity were investigated. PLA microspheres with a drug content of 1.5-11.0% were prepared by a novel o/w (oil-in-water) solvent evaporation method. Both DL-PLA and NA were amorphous in form, and an increase in heat capacity at glass transition temperature (Tg) of the polymer was observed in DL-PLA microspheres containing NA. The Tg of DL-PLA (PLA2000 bulk) was 307.8 K, while Tg of microspheres containing NA (content 6.0%) shifted to 321.2 K. The Tg of PLA2000 microspheres was found to increase with an increase in the content of NA, and its increasing tendency reached a plateau at an NA content of greater than 6%. The apparent activation energy of glass transition of PLA2000 bulk and the microspheres was calculated to be 86.3 and 99.3 kcal/mol, respectively. As a result of the release test after storage at 4 degrees C and 40 degrees C for 1 month, nearly the same release profiles of NA from PLA2000 microspheres were found. The release rate of NA after the initial release became slow after storage at 45 degrees C for 1 month. This may be attributed mainly to a decrease in surface area caused by the formation of agglomerates of PLA2000 microspheres under conditions near Tg.

Drug Storage↗
PubMed1991

Role of paracellular pathway in nonelectrolyte permeation across rat colon epithelium enhanced by sodium caprate and sodium caprylate.

The enhancing effects of 0.25% sodium caprate (C10) and sodium caprylate (C8) on the paracellular permeation of seven water-soluble nonelectrolytes (inulin, polyethylene glycol 900, mannitol, erythritol, glycerol, thiourea, and urea) across the isolated rat colonic epithelium were examined using the Ussing-type chamber technique. The paracellular changes were also measured by impedance analysis. In both the presence and the absence of enhancers, the permeation clearances (Pm) for inulin (12-15 A in molecular radius) to erythritol (3.2 A) increased linearly with the increase in their free diffusion coefficients (Dfr), showing the existence of a paracellular shunt pathway unrestricted to any molecular size. Glycerol (2.9 A), thiourea (2.6 A), and urea (2.3 A) had higher clearances than the expected linear values, showing the existence of a restricted paracellular or transcellular pathway. Both C10 and C8 increased the permeabilities in the two pathways, but C10 was more effective than C8. The increase in the permeabilities via the shunt pathway caused by the enhancers was greater than that via the restricted pathway, and thus, the two-phase pattern in the relationship of Pm and Dfr was similar to that in the absence of enhancers. The transcellular permeabilities for urea and thiourea, which were obtained from the efflux experiments, were increased by the enhancers. However, the relative increase caused by C10 was smaller than that of the paracellular-restricted permeabilities. The paracellular changes probably were due to the increase in pore area per unit diffusive path length.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Protective effect of vitamin A against the methotrexate-induced damage to small intestine: a study on the crypt cells.

Vitamin A (VA) protects the small intestine from the methotrexate (MTX)-induced damage. The in vivo effects of MTX and/or VA on crypt cells of small intestine were investigated using rats orally administered MTX (15 mg/kg body weight) and/or VA (5,000 IU/kg body weight). The thymidine kinase activity of crypt cells separated from villus cells of small intestine of MTX plus VA-treated rats was lower than that from control rats but higher than that from MTX-treated rats. VA-treated rats showed almost the same activity of thymidine kinase as control rats. The amounts of the end products, adenosine monophosphate (AMP) and guanosine monophosphate (GMP), contained in crypt cells of treated rats were determined to investigate the in vivo effects of MTX and/or VA on de novo purine synthesis. MTX treatment significantly decreased the amounts of both AMP and GMP but both amounts were not affected by MTX plus VA treatment. Treatment with VA alone appeared to increase their amounts slightly. Thus, although the oral administration of MTX to rats inhibited DNA synthesis in crypt cells, VA coadministration protected the salvage pathway of pyrimidine synthesis and the de novo purine synthesis in crypt cells.

Animals↗
PubMed1991

Paracellular and transcellular permeabilities of fosfomycin across small intestinal membrane of rat and rabbit by voltage-clamp method.

The permeability of fosfomycin (FOM), which is a low molecular weight and water-soluble antibiotic, across rat and rabbit jejunal membrane was investigated on a paracellular route and a transcellular route separated by voltage-clamp method. It was determined that FOM permeates through these two routes in both animals. Under a physiologically normal condition, the transmucosal electrical potential difference (about 2 mV), the contribution of the transcellular route to FOM membrane permeability was greater than that of the paracellular route. The transcellular permeability was significantly reduced in the presence of inorganic phosphate. The inhibitory effects of the inorganic phosphate coincided with our reports on FOM uptake by rat jejunal brush-border membrane vesicles in vitro and on FOM absorption by rat jejunal single-pass perfusion in situ.

Algorithms↗
PubMed1991

Hepatic uptake of lipid-soluble drugs from fat emulsion.

Oil violet in a fat emulsion was taken up into the parenchymal cells of rat liver in vitro. The uptake was greater at 37 degrees C than 25 degrees C or 4 degrees C, and it was increased by addition of postheparin plasma including lipoprotein lipase activity into the reaction medium. The uptake from the emulsion with smaller particles was greater than that from the emulsion with larger particles. The hepatic uptake of 14C-cholesteryl oleate in the emulsion by recirculating perfusion of the liver in situ was also increased by postheparin plasma in the perfusion medium. Its enhancing effect was found for distribution in the parenchymal cells but not in the Kupffer cells. The previous perfusion of Intralipos of the commercial fat emulsion reduced the hepatic uptake of 14C-cholesteryl oleate in the emulsion. The emulsion particle sizes were reduced by postheparin plasma both in vitro and in situ. Consequently, it was suggested that a lipid-soluble compound entrapped in the fat emulsion is taken up into the parenchymal cells by receptor-mediated process via the reduced particle sizes emulsion (remnant), which is a mechanism similar to the dietary fat metabolism.

Animals↗