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Biomedical subjects

S Awazu

Publications and source records attributed to S Awazu.

At least 55 records · Page 3Linked to original sources
PubMed1997

Peripherally active analgesia of aminopeptidase-resistant sugar-coupled leucine enkephalin.

Aminopeptidase-degradable leucine enkephalin (LE) was coupled with disaccharide (cellobiose or gentiobiose). Acetic acid writhing assay (for peripheral effect) showed that cellobiose-coupled LE (CcpLE) as well as LE had analgesic activity by subcutaneous (s.c.) administration to mice pretreated (s.c. administration) with peptidase inhibitors, whereas any analgesic effect was not observed after s.c. administration of CcpLE or LE without peptidase inhibitors. However, gentiobiose-coupled LE (EcpLE) did not have analgesic activity even with pretreatment of peptidase inhibitors. On the other hand, hot-plate assay (for central effect) did not indicate obvious analgesic effect after s.c. administration of CcpLE or EcpLE with pretreatment of peptidase inhibitors. Significant difference of stability against peptidase was not observed between CcpLE and EcpLE. Therefore, it was concluded that CcpLE is a peripherally active analgesic.

Aminopeptidases↗
PubMed1997

Hepatic uptake of p-nitrophenyl sulfate by transporter that acetaminophen sulfate shares for uptake: sulfate moiety as a vector for metabolite transport.

Hepatic uptake of the sulfate conjugate of p-nitrophenol (p-NPsul) has been studied. Uptake clearance of p-NPsul by isolated rat hepatocytes was dependent on p-NPsul concentration, suggesting carrier-mediated transport. The uptake of p-NPsul by isolated rat hepatocytes was inhibited by acetaminophen sulfate (APAPsul), the uptake of which had been previously reported to be inhibited by p-NPsul. The hepatic uptake of p-NPsul was also inhibited by bromosulfophthalein (BSP) or dibromosulfophthalein (DBSP), which had been reported to inhibit hepatic uptake of APAPsul in the previous study. These inhibitory effects were observed in isolated perfused liver experiments as well as in isolated hepatocyte experiments. Therefore, it was concluded that hepatic uptake of p-NPsul was mediated by a transporter, which mediates hepatic uptake of APAPsul as well as BSP or DBSP. It is suggested that sulfate moiety may have a key role as a vector for the hepatic transport of sulfate conjugate metabolites. Interaction between sulfate conjugate metabolites in hepatic uptake may also be expected.

Acetaminophen↗
PubMed1996

Absorption-enhancing mechanism of EDTA, caprate, and decanoylcarnitine in Caco-2 cells.

The mechanism of paracellular expansion by absorption enhancers, e.g., EDTA, sodium caprate (C10), and decanoylcarnitine (DC), was studied, the focus being on the process of actin microfilament contraction in the tight junction. The effects of various inhibitors such as KN-62 (a specific inhibitor of Ca2+/calmodulin dependent protein kinase), H7 (a protein kinase C (PKC) inhibitor), and W7 (a calmodulin antagonist) were examined on the paracellular expansion by the enhancers in Caco-2 cells. From the experimental results, the following mechanisms were suggested. EDTA activates PKC by depletion of extracellular calcium via chelation resulting in expansion of the paracellular route. C10 increases the intracellular calcium level by an interaction with the cell membrane independent of cell polarity resulting in contraction with actin microfilament. DC interacts specifically with the apical membrane to increase the intracellular calcium level, but the mechanistic details subsequent to the increase of calcium are not clear.

Caco-2 Cells↗
PubMed1996

Improvement of intestinal absorption of leucine enkephalin by sugar coupling and peptidase inhibitors.

Peptidase-degradable leucine enkephalin (LE) was coupled with cellobiose or gentiobiose. In the absorption experiments, cellobiose-coupled LE (CcpLE) was more stable than LE itself on the mucosal side, and CcpLE appeared on the serosal side. Destyrosyl LE coupled with cellobiose was not formed, indicating that sugar coupling provided LE with aminopeptidase resistance. In the presence of inhibitors of angiotensin-converting enzyme and enkephalinase, the stability of CcpLE on the mucosal side was increased, and as a result more was absorbed. Furthermore, the absorption clearance was much higher than the value expected from the mucosal concentration of CcpLE. Similar results were observed in the absorption of gentiobiose-coupled LE. In the LE absorption experiment, however, LE was not detected on the serosal side even in the presence of these peptidase inhibitors. Improvement of intestinal absorption by sugar coupling and peptidase inhibitors was evaluated kinetically, indicating the exclusive contribution of metabolic degradation of LE through intestinal tissues to the absorption process.

Animals↗
PubMed1996

Pulmonary absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) after intratracheal administration to rats.

Pulmonary absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) was examined in the rat. The relative bioavailabilities of rhG-CSF after intratracheal administration to intravenous and subcutaneous means were 11.6% and 27.4%, respectively, which were evaluated from the ratio of area under the curve (AUC) of the plasma rhG-CSF concentration versus time for 8 h. The pharmacological availability after the pulmonary absorption was determined from the AUC for the increase ratio in total blood leukocyte numbers versus time curve. The availability was equal to or more than the availabilities after intravenous or subcutaneous administration. Comparison of the two different parenteral administration routes for rhG-CSF, intratracheal and intranasal showed the pharmacological availability after the intratracheal administration to be superior. The pulmonary absorption of rhG-CSF is thus an effective parenteral route of administration.

Absorption↗
PubMed1996

Retention mechanism of imidazoles in connective tissue. I. Binding to elastin.

To elucidate the retention mechanism of drugs with imidazole moiety in the connective tissue, the retention form and site of [2-14C]imidazole and 2-methyl[2-14C]imidazole were studied after intravenous administration to rats (3 micromol/kg body weight). The aorta, which is representative of the connective tissue, retained considerable radioactivity after dosing for both the imidazoles. It was observed that most of the aortic radioactivity came from the irreversibly bound fraction with elastin and that this was in close agreement with the microautoradiographic observation that showed that the retention of radioactivity occurred near the elastic fiber in the aorta. Pretreatment of rats with SKF525-A significantly increased the irreversible binding of radioactivity from the imidazoles in aorta, whereas neither phenobarbital nor 3-methylcholanthrene increased the binding. Regarding the urinary metabolite profile, the excretion of intact form significantly increased by SKF525-A pretreatment for imidazole, and an increasing tendency was also observed for 2-methylimidazole. However, no in vitro irreversible binding of imidazoles to aortic tissue was observed after incubating at physiological pH and temperature. These findings indicate that the retention of drugs with imidazole moiety in the connective tissue is largely attributable to irreversible binding between the imidazole moiety and elastin, and that the binding may be mediated through cytochrome P450-independent biotransformation.

Animals↗
PubMed1995

Oxidative stress in isolated rat hepatocytes during naproxen metabolism.

Naproxen, a non-steroidal anti-inflammatory drug, induced lipid peroxidation in isolated hepatocytes of rats. The viability of the hepatocytes decreased upon lipid peroxidation, and this effect was accompanied by the formation of high molecular weight protein aggregates in the hepatocytes. Protein aggregation occurred slowly compared with the formation of thiobarbituric acid reactive substances (TBARS). The increase of TBARS was strongly correlated with the decrease of intracellular glutathione. Chemiluminescence was produced from the hepatocyte suspension during naproxen metabolism, and was correlated with the formation of TBARS. These results indicate that lipid peroxidation in the hepatocytes was provoked by reactive oxygens produced in the process of naproxen metabolism.

Animals↗
PubMed1995

Development and evaluation of a new automated dispensing system.

Promptness of medicine preparation is one of the important tasks the pharmacy has to tackle. A new automated dispensing system has been developed in order to adopt parallel preparation of the prescription. The system consists of a large LAN system which is connected to a host-computer, control-computer, automatic preparation machines and conveyer lines. The prescription data issued by each physician are first audited by the host computer and then used as the date for preparation. Prepared data checked by pharmacists are delivered to the manual preparation station (tablets, powder, topical drugs, and solutions) as a preparation instruction sheet and transmitted directly to the automatic preparation machines (e.g. medicine bag printing machines and automatic tablet dispensing and packaging machines). In collecting the prepared medicines, a controlled conveyer line was established. The waiting time decreased significantly after the system was introduced. This system not only reduces actual medicine preparation time but also improves the progress of the dispensing operation efficiency.

Automation↗
PubMed1995

Fluorescent substances and high molecular weight protein aggregates formed in rat heart mitochondria upon doxorubicin-induced lipid peroxidation.

A rat heart mitochondrial suspension was incubated with doxorubicin, FeCl3 and NADH. Fluorescent substances and high molecular weight protein aggregates were observed in the mitochondrial membranes upon the formation of thiobarbituric acid-reactive substances. Since both fluorescent substances and high molecular weight protein aggregates are retained in mitochondrial membranes, they can be of use in the clarification of the site of doxorubicin-induced lipid peroxidation.

Animals↗
PubMed1995

Absorption-enhancing mechanism of sodium caprate and decanoylcarnitine in Caco-2 cells.

The mechanism of action of the absorption enhancers such as sodium caprate (C10) and decanoylcarnitine (DC) was examined. Both C10 and DC increased the epithelial permeability of fluorescein isothiocyanate dextran 4000 and decreased the transepithelial electrical resistance in Caco-2 cell monolayer. Irrespective of the presence or absence of mucosal calcium, C10 rapidly increased intracellular calcium levels dose-dependently. Compound 48/80, a phospholipase C inhibitor, prevented the increases of the intracellular calcium level and permeability of fluorescein isothiocyanate dextran 4000 by C10. Furthermore, N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride, a strong calmodulin inhibitor, also significantly decreased the enhancing effect of C10. These results suggest that C10 releases calcium from intracellular stores via activation of phospholipase C in plasma membrane. The increase of the calcium levels was considered to induce the contraction of calmodulin-dependent actin microfilament, followed by dilatation of the paracellular route. Although DC also increased intracellular calcium levels, neither compound 48/80 nor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide hydrochloride decreased the enhancing effect of DC. The enhancing mechanisms were different for C10 and DC.

Calcium↗
PubMed1994

Na(+)-dependent transport of aminopeptidase-resistant sugar-coupled tripeptides in rat intestine.

Aminopeptidase-degradable tripeptide, tyrosylglycylglycine (TGG, a part of aminopeptidase-degradable enkephalines), was coupled with sugars (cellobiose, maltose, lactose, gentiobiose and glucose). These sugar-coupled TGGs were stable enough to be transported from the mucosal to the serosal side in rat everted small intestine, while TGG was not stable enough to be transported. The transport of sugar-coupled TGGs was decreased in the absence of Na+, indicating the Na(+)-dependent transport of sugar-coupled TGG in rat intestine. Cellobiose-coupled TGG and glucose-coupled TGG did not mutually inhibit their transport. It was suggested that the intestinal Na(+)-dependent transporter for disaccharide-coupled tripeptides, which have a pyranose ring, was different from that of monosaccharide-coupled tripeptide, which has no pyranose ring.

Amino Acid Sequence↗
PubMed1994

The beta-anomeric and glucose preferences of glucose transport carrier for intestinal active absorption of monosaccharide conjugates.

The anomeric preference for intestinal absorption of glucosides and galactosides (1- and 2-naphthyl glycosides) was studied by the everted rat intestine method. After the absorption of beta-glucoside and beta- and alpha-galactosides, the glycosides itself appeared on the serosal side, whereas after the alpha-glucoside absorption, the glucoside itself was not detected on the serosal side, but a large amount of aglycone appeared instead. This indicates an alpha-anomeric preference of desglucosylation through the intestinal membrane. A significant decrease of the total (glycoside + aglycone + glucuronide metabolites) amount transported to the serosal side in the absence of Na+, a cosubstrate of the glucose transport carrier (GTC), was observed in alpha- and beta-glucosides and beta-galactoside, but not in alpha-galactoside. This indicates the poor contribution of GTC to the alpha-galactoside absorption. The Na(+)-dependent absorption of the glycosides by the GTC were beta-glucoside > alpha-glucoside > beta-galactoside (for 2-naphthyl glycosides), and beta-galactoside > alpha-galactoside (for 1-naphthhyl glycosides). These results and those of a previous study led to the conclusion that the intestinal glucose transport carrier prefers beta-anomer to alpha-anomer, and glucose to galactose for monosaccharide conjugates absorption.

Animals↗
PubMed1994

Chemiluminescence associated with doxorubicin-induced lipid peroxidation in rat heart mitochondria.

Chemiluminescence was observed in a rat heart mitochondrial suspension containing NADH, FeC1(3) and doxorubicin (Adriamycin) (DXR). There was good correlation between the total intensity of chemiluminescence and the total amount of thiobarbituric acid reactive substances (TBARS) produced during DXR redox cycling. Thus, the chemiluminescence was shown to be associated with lipid peroxidation. The chemiluminescence was quenched by superoxide dismutase (SOD), suggesting that superoxide anion radicals contributed to its production. Upon addition of 1,4-diazabicyclo[2,2,2]-octane (DABCO), a singlet oxygen emission enhancer, to the mitochondrial suspension emitting the chemiluminescence, the chemiluminescence intensity increased transiently, indicating the involvement of singlet oxygen. Furthermore, spectral analysis of the chemiluminescence showed it to be due to singlet oxygen and excited carbonyls.

Animals↗
PubMed1994

Transport of low and high molecular peptides across rabbit Peyer's patches.

The permeability of peptides across rabbit jejunal epithelium (JE) and Peyer's patches (PP) was compared. Kyotorphin (L-tyrosyl-L-arginine) was almost completely hydrolyzed during its membrane transport in both PP and JE, but [D-Arg2]Kyotorphin (L-tyrosyl-D-arginine) was less hydrolyzed in PP than in JE. Since the permeability of intact [D-Arg2]Kyotorphin was almost equal in PP and JE, no superiority of PP to JE was found for dipeptide transport. More intact fluorescein isothiocyanate (FITC)-labeled bovine serum albumin (FITC-BSA) and concanavalin A (FITC-Con A) were transported in PP than in JE. At both absorption sites, the transport of the intact FITC-Con A was superior to that of the intact FITC-BSA. Colchicine significantly reduced the total transport of the intact and degradation forms of both peptides and the reduction ratio was greater in PP than in JE. Accordingly, it was suggested that PP can be used as prominent absorption sites for polypeptides since they have lower peptidase activity and higher endocytosis activity than JE.

Animals↗
PubMed1994

Lipid peroxidation and chemiluminescence during naproxen metabolism in rat liver microsomes.

1. Rat liver microsomal suspension containing NADPH and MgCl2 was incubated at 37 degrees C with naproxen, a non-steroidal anti-inflammatory drug. Thiobarbituric acid reactive substances (TBA-RS), high molecular weight protein aggregates and fluorescent substances were formed in the microsomal suspension. 2. Chemiluminescence was produced from the microsomal suspension. This chemiluminescence production was well correlated to the TBA-RS formation, indicating that the chemiluminescence production was closely associated with the lipid peroxidation. 3. The addition of SKF-525A to the microsomal suspension inhibited the production of TBA-RS, chemiluminescence and 6-demethylnaproxen (6-DMN), the oxidative product of naproxen. Further, the antioxidant, alpha-tocopherol and singlet oxygen quenchers like histidine, dimethylfuran and 1,4-diazabicyclo[2,2,2]octane strikingly inhibited the productions of chemiluminescence and TBA-RS. 4. Neither naproxen nor 6-DMN caused lipid peroxidation in the absence of NADPH. Thus, lipid peroxidation and chemiluminescence during the oxidation of naproxen in liver microsomes was suggested to be provoked by reactive oxygen species and an origin of chemiluminescence was shown to be singlet oxygen.

Animals↗
PubMed1994

Effects of surfactants and protease inhibitors on nasal absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) in rats.

The effects of various surfactants and protease inhibitors on the nasal absorption of recombinant human granulocyte colony-stimulating factor (rhG-CSF) were examined in rats. No effects of bile salts and acids such as sodium glycocholate or taurocholic acid, amphoteric surfactants such as lauryldimethyl betaine, or anionic surfactants such as sodium lauryl sulfate on the absorption were found at a concentration of 1%. But non-ionic surfactants with hydrophile/lipophile balance (HLB) of 13 to 18 increased the total leukocyte numbers maximally by about 250% as a relative increase ratio to the control without surfactants. The increase in the plasma rhG-CSF concentration was obviously observed only in the presence of non-ionic surfactants, and in particular, the effects of Laureth-9 on the increase in total leukocyte numbers and plasma rhG-CSF concentration were maximal. In the presence of various kinds of protease inhibitors, the increasing effect of rhG-CSF on the total leukocyte numbers was not changed. Consequently, it is considered that the permeation of rhG-CSF through the nasal epithelium can be improved by non-ionic surfactants, but the effect of a protease inhibitor is smaller than that of the surfactant.

Absorption↗
PubMed1994

Comparison of absorption-enhancing effect between sodium caprate and disodium ethylenediaminetetraacetate in Caco-2 cells.

The effects of sodium caprate (C10) and disodium ethylenediaminetetraacetate (EDTA) on the epithelial permeability of polyethylene glycol 4000 (PEG4000) were examined in Caco-2 cell monolayers on the polycarbonate membrane (filter) of a Transwell cluster dish. Under serosal Ca(2+)-free conditions irrespective of the presence or absence of mucosal Ca2+, the permeability of PEG4000 was remarkably enhanced, even in the absence of enhancer. For control experimental conditions with a permeation enhancer in Caco-2 cells, Ca2+ was added to both the mucosal and serosal sides. Under the control conditions, EDTA increased the permeability of PEG4000 to 14 times the control and C10 by 3.5 times. Mucosal Ca(2+)-free conditions further increased the EDTA-enhancing effect, to 29 times the control value. In contrast to the EDTA effect, however, the C10 effect was unchanged in the absence of mucosal Ca2+. These results suggest that the EDTA effect is induced by chelation with Ca2+ but that C10 has some other action in addition to chelation.

Calcium↗