Biomedical subjects

M Hashida

Publications and source records attributed to M Hashida.

At least 37 records · Page 2Linked to original sources

PubMed1990

Disposition of anticancer drugs after bolus arterial administration in a tissue-isolated tumor perfusion system.

Disposition characteristics of various anticancer drugs in a tissue-isolated tumor preparation were studied in Walker 256 carcinosarcoma-bearing rats using an in situ single-pass vascular perfusion technique. Three anticancer drugs, 5-fluorouracil, mitomycin C, and Adriamycin, and two lipophilic prodrugs of mitomycin C were tested in the tumor preparation perfused with Tyrode's solution containing 4.7% bovine serum albumin. After bolus arterial injection of test drugs, their outflow concentration-time curves were analyzed based on statistical moment theory. In each tumor preparation, the injection of drug was paired with that of vascular reference substance, Evans' blue-labeled bovine serum albumin, and disposition parameters of the drug were corrected with those of vascular reference substance. From the mean transit time values of vascular reference substance, the average vascular volume of the tumor preparation was calculated to be 0.063 ml/g, which decreased with tumor growth. All drugs showed significant extraction by the tumor tissue, depending on their physicochemical properties. Distribution volumes of tested drugs were from 1.53 to 3.33 times larger than the vascular volume. Calculated intrinsic clearance values for the protein-unbound fractions increased as the lipophilicity of the drug increased. The potential increase in tumor uptake was observed in lipophilic prodrugs of mitomycin C. The present experimental system is thus suggested to be useful for analyzing drug disposition in tumor tissue.

Animals↗

PubMed1990

Effect of medium-chain glycerides on the intestinal absorption of phenol red: studies on mechanisms of the promoting effect.

To elucidate the mechanisms of the promoting action of medium-chain glyceride (MCG) on the intestinal absorption of phenol red (PR), the effect of different MCG dose levels on PR absorption, the absorption kinetics of MCG itself, and the mucosal reduced glutathione (GSH) levels were investigated to determine whether or not they are related to the promoting action of MCG. The absorption of PR was found to be enhanced with an increase in MCG dose (as an emulsion in the range 0.5-4.0%). Urinary excretion of PR was reduced by absorbed MCG components, which also resulted in an increase in the AUC. Moment analysis of plasma PR concentrations after intraintestinal administration revealed a shorter mean absorption time (MAT) for the emulsion formulation than for the control. The mucosal GSH level was lowered by the administration of the MCG emulsion (2-10%) into the intestinal lumen. Pretreatment with a 4% MCG emulsion decreased GSH levels to one-half of the control. In these cases, the level of mucosal GSH seemed to remain constant to the end of the experiment after it had decreased during the initial period. On the other hand, results from the in situ loop or recirculation study showed that enhancement of PR absorption appeared in the earlier period and then gradually decreased. The time course of the PR absorption rate, estimated from plasma concentration data, was similar to that of the MCG absorption rate. These results suggest that the promotion of intestinal absorption is related to the absorption kinetics of MCG itself, but not directly to the level of mucosal GSH.

Animals↗

PubMed1990

Statistical moments and disposition parameters in a local perfusion system under mammillary nonequilibrium condition.

Application of the statistical moment analysis to the local organ perfusion system leads moment parameters (moments) from the venous outflow concentration-time curve (dilution curve) of drug after its intra-arterial bolus injection. By introducing the chromatographic concept and the network theory, we had defined the disposition parameters such as steady state distribution volume, mean elimination time, and intrinsic clearance from moments based on the well-stirred model. In this paper, discussion was expanded to general two-compartment organ perfusion models and the meanings of these disposition parameters in them were investigated. The relationship between compartmentally defined microconstants and moments-oriented disposition parameters was examined and the effect of the nonequilibrium (mainly peripheral elimination) condition on the latter was discussed. The possible utility of the disposition parameters as noncompartmental indications of drug disposition characteristics was suggested.

Models, Biological↗

PubMed1990

Disposition characteristics of macromolecules in tumor-bearing mice.

As part of the strategy for the design of macromolecular carriers for drug targeting, the disposition characteristics of macromolecules were studied in mice bearing tumors that served as target tissues. Eight kinds of macromolecules including four polysaccharides and four proteins with different molecular weights and electric charges were used; tissue distribution and tumor localization after intravenous injection were studied. Pharmacokinetic analysis revealed that the tissue radioactivity uptake rate index calculated in terms of clearance was different among the tested compounds; especially, the urinary radioactivity excretion clearances and the total hepatic radioactivity uptake clearances varied widely. Compounds with low molecular weights (approximately 10 kD) or positive charges showed lower tumor radioactivity accumulation; radioactivity was rapidly eliminated from the plasma via rapid urinary excretion or extensive hepatic uptake, respectively. On the other hand, large and negatively charged compounds, carboxymethyl dextran, bovine serum albumin, and mouse immunoglobulin G, showed higher radioactivity accumulation in the tumor (calculated total amounts were 15.6, 10.8, and 20.8% of the dose, respectively) and prolonged retention in the circulation. These results demonstrated that the total systemic exposure rather than the uptake rate index was correlated with total tumor uptake. Molecular weight and electric charge of the macromolecules significantly affected their disposition characteristics and, consequently, determined radioactivity accumulation in the tumor. It was concluded that a drug-carrier complex designed for systemic tumor targeting should be polyanionic in nature and larger than 70,000 in molecular weight.

Animals↗

PubMed1990

Intestinal transport of sulfanilic acid in rats immunized with protein-sulfanilic acid conjugate.

Intestinal transport of sulfanilic acid was examined by means of an in vitro everted sac technique in rats immunized with a bovine gamma-globulin-sulfanilic acid conjugate. At a low concentration of sulfanilic acid, the intestinal transport of sulfanilic acid was decreased in rats immunized with bovine gamma-globulin-sulfanilic acid conjugate. This phenomenon was dose dependent and antigen specific, since there was no difference in the transport of sulfanilic acid at a high concentration and of an unrelated hapten. These results suggested that parenteral immunization impaired not only the intestinal transport of macromolecular antigens, as previously shown, but also the transport of the low molecular weight hapten, sulfanilic acid.

Animals↗

PubMed1990

Percutaneous penetration of acyclovir through excised hairless mouse and rat skin: effect of vehicle and percutaneous penetration enhancer.

The effects of vehicle and percutaneous penetration enhancer on the penetration of acyclovir through excised hairless mouse and rat skin were investigated. Four solvents, propylene glycol (PG), ethanol (ET), isopropanol (IPA), and isopropyl myristate (IPM), were employed as vehicles, in combination with four enhancers, 1-farnesylazacycloheptan-2-one (7FU), 1-geranylazacycloheptan-2-one (7GU), 1-geranylazacyclopentan-2-one (5GU), and 1-dodecylazacycloheptan-2-one (Azone). Acyclovir was suspended in vehicles to avoid the effect of the thermodynamic activity of acyclovir in the vehicle. The penetration of acyclovir through hairless mouse skin from IPA was enhanced by 7GU, whereas that from IPM was not affected. All combinations of vehicle and penetration enhancer were examined using rat skin. No effect of the enhancers was observed in the IPM vehicle. The estimated solubility parameters of vehicles and enhancers indicated that the polarities of IPM and the enhancers are similar, which prevents effective penetration of the enhancers from IPM. However, the penetration of acyclovir from the other vehicles was increased by the enhancers. The combination of hydrophilic vehicle and hydrophobic enhancer resulted in a large enhancing effect. The disappearance of the enhancers from the vehicle correlated with their enhancing activity, but other factors also seemed to affect the penetration enhancement of acyclovir.

Acyclovir↗

PubMed1990

Biliary excretion of mitomycin C dextran conjugates in relation to physicochemical characteristics of carrier dextran.

Biliary excretion characteristics of polymeric prodrugs of mitomycin C (MMC), mitomycin C-dextran conjugates with cationic or anionic charge (MMC-Dcat, MMC-Dan) and with different molecular weights of dextran (10,000, 70,000, and 500,000) were studied in rat. Following intravenous injection, bile was periodically collected and concentrations of free and dextran-conjugated MMC in it were determined by bioassay. MMC administered as a free form was excreted rapidly into bile and 1.8% of the dose was recovered within 2 h. A small amount of MMC was gradually excreted into bile after administration of all MMC-Ds and total recovery at 8 h was less than 1% of dose. In this case, a major part of excreted MMC was recovered as a conjugated form. MMC-Dcat gave a larger total excretion of MMC than MMC-Dan and excretion was also affected by the molecular weight of carrier dextran. The biliary recovery of MMC-Dcat labeled with 14C at a spacer moiety was significantly higher than that of conjugated MMC determined by bioassay suggesting release and/or inactivation of MMC in MMC-D during the circulation in the body. These results were compared with biliary excretion of model macromolecules with the same molecular weight but different electric charge in order to clarify the effect of electric charge on the biliary excretion of macromolecules. Cationic macromolecules exhibited higher biliary excretion in relation to greater hepatic uptake.

Animals↗

PubMed1990

Effect of medium-chain glycerides on the membrane transport of D-glucose and sulfanilic acid in the intestinal brush-border membrane vesicles.

To clarify the influence of medium-chain glycerides (MCG) on a biological membrane, we investigated the membrane transport of D-glucose and sulfanilic acid in the brush-border membrane (BBM) vesicles pretreated with MCG. The size distribution of the BBM vesicles determined by electron microscopic observation was not significantly different between the vesicles incorporated with MCG and those of the control. However, the amount of D-glucose taken up by the vesicles at an equilibrated stage (30 min) was significantly decreased in the MCG-treated ones based on unit content of protein. Based on these results we estimated the membrane transport of D-glucose and sulfanilic acid in consideration of vesiculation or filter-capturing efficiency in MCG-treated vesicles. The rates of Na+ gradient-independent D-glucose transport and sulfanilic acid transport were significantly greater in MCG-treated vesicles than in the control. On the other hand, the magnitude of overshooting effect in Na+ gradient-dependent uptake of D-glucose in MCG-treated vesicles was maintained similar to the control. Comparison of kinetic parameters for active D-glucose transport at different concentrations indicated that Km and Vmax were not significantly different between MCG-treated and the control vesicles. These results indicated that passive diffusion of D-glucose and sulfanilic acid was significantly increased but Na(+)-glucose cotransporter was not significantly changed by the incorporation of MCG in the intestinal BBM vesicles.

Benzenesulfonates↗

PubMed1990

Biochemical and biopharmaceutical properties of macromolecular conjugates of uricase with dextran and polyethylene glycol.

Uricase (UC) was conjugated with dextran and polyethylene glycol and their biochemical and biopharmaceutical properties were studied. UC-dextran conjugates (UC-D) synthesized by four methods, periodate oxidation, cyanogen bromide, carbodiimide and cyanuric chloride largely retained the UC enzymatic activity depending on the extent to which they modified amino groups. The periodate oxidation method seemed best because it gave a conjugate with high yield and satisfactory activity retention. The conjugate of UC with activated polyethylene glycol (UC-PEG2) was also obtained with high yield but the remaining activity was somewhat lower than those of dextran conjugates at the same modification extent. UC-D and UC-PEG2 showed sustained enzymatic activity in plasma after intravenous injection to rats. The advantage of chemical modification of proteins, especially with dextran, by the periodate oxidation method for preparation of a protein-delivery system was thus suggested.

Animals↗

PubMed1989

Characterization of mitomycin C-induced gastrointestinal damage. I. In situ recirculation experiment.

The effects of mitomycin C (MMC), an anti-tumor agent, on the intestinal absorption of various drugs in rats were investigated. Based on microscopic observations, preadministration of a single intravenous dose of MMC (3 mg/kg) caused serious degeneration of epithelial cells, villous atrophy, and mitotic arrest in crypts at 48 hr after pretreatment. At this time point, absorption of sulfanilamide, salicylic acid, cephalexin, and L-tryptophan was shown to be significantly decreased by means of an in situ recirculation technique. The histological changes and the decrease in absorption of sulfanilamide, a model for passively absorbed drugs, were shown to depend on the timing of MMC pretreatment. Maximal effects were observed 48 hr after dosing. The MMC-induced reduction in the absorption of drugs was not a result of differences between treated and control animals with respect to pH of the drug solution, binding of drugs with intraluminal macromolecules, or intestinal mucosal blood flow. The absorption of sulfanilamide from the small intestine in the in situ system correlated well with the wet weight of the small intestine regardless of pretreatment dose or route. This suggests that the change in absorptive surface area of the intestinal mucosa may play a major role in the MMC-induced decrease in absorption capacity of the intestine.

Animals↗

PubMed1989

Characterization of mitomycin C-induced gastrointestinal damage. II. In vitro everted sac experiment.

The everted gut sac technique was employed to clarify the effects of preadministration of mitomycin C (MMC) on intestinal transport of various drugs. Loss of intestinal tissue weight and increase in mucosal-to-serosal fluxes of passively absorbed drugs were noted in the case of MMC pretreatment, although the extent of the latter effect varied according to the inherent absorbability of each drug. The maximal effect of MMC on intestinal tissue weight and transport of sulfanilamide, a model of a passively absorbed drug, was observed 48 hr after pretreatment. The increase in the transfer of sulfanilamide correlated well with the MMC-induced decrease in intestinal tissue weight. These phenomena may result from the shortened transfer distance from mucosal to serosal fluid and impaired barrier function of the intestinal mucosa. On the other hand, transport of actively absorbed 3-O-methyl-D-glucose was not influenced by MMC pretreatment, which could be explained by an increment in the passive permeation counterbalancing the decrement in the active permeation. The present study also suggested that the measurement of transport of drugs through everted gut sacs might be useful as a simple and qualitative index of gastrointestinal mucosal damage.

3-O-Methylglucose↗

PubMed1989

Disposition of a polymeric prodrug of mitomycin C, mitomycin C-dextran conjugate, in the perfused rat liver.

The disposition of a polymeric prodrug of mitomycin C (MMC), mitomycin C-dextran conjugate (MMC-D), was studied in the single-pass perfused rat liver in order to clarify the effect of physico-chemical properties, such as molecular weight and electric charge, on the hepatic uptake of MMC-D. Six types of MMC-D were used: both cationic MMC-D (MMC-Dcat) and anionic MMC-D (MMC-Dan) conjugated with dextran with molecular weights of 10,000, 70,000, and 500,000. Outflow curves were analyzed using statistical moment theory. Remarkable hepatic uptake of MMC-Dcat was observed and the uptake amount increased with an increase in molecular weight (i.e., approximately 80% of the dose was taken up by the liver during a single passage of the conjugate with a molecular weight of 500,000). Intrinsic clearance (CLint,i) and apparent distribution volume (Vi) also increased as the molecular weight increased. On the other hand, almost 100% of applied MMC-Dan was recovered in the outflow regardless of molecular weight, with almost the same moment parameters as those of the vascular reference substance (VRS), 131I-labeled human serum albumin (HSA). In a repeated application, the uptake of MMC-Dcat decreased in a stepwise manner, suggesting a saturation in the hepatic uptake of MMC-Dcat, while the uptake of MMC-Dan was unchanged. The MMC-Dcat pretreatment also affected the uptake of Evans blue (EB) bound to bovine serum albumin (BSA). These results demonstrate that molecular weight and electric charge determine the hepatic disposition of macromolecular prodrugs.

Animals↗

PubMed1989

Control of pharmaceutical properties of soybean trypsin inhibitor by conjugation with dextran. I: Synthesis and characterization.

The Kunitz-type soybean trypsin inhibitor (STI), a model protein, was conjugated with dextran (Mw, approximately 9900; STI-D), and its physicochemical and biochemical properties were studied to develop a novel delivery system for a protein drug. Conjugation was carried out using periodate oxidation, and cyanogen bromide, carbodiimide, cyanuric chloride, epichlorhydrin, and N-succiniimidyl-3-(2-pyridyldithio)propionate (SPDP) reagent methods. Dextran was conjugated to STI at a molar ratio of 1.5 to 4.6, but the degree of modification, as well as yield and contamination extent of unreacted STI and dextran, varied with the method of synthesis. Gel filtration and electrophoresis confirmed the covalent attachment of dextran to STI but also demonstrated the broad molecular weight distribution of the conjugates. The STI-D conjugate retained satisfactory activity, although the attachment partially reduced its inhibitory activity against trypsin. The periodate oxidation method seemed to be the best for the preparation of STI-D since it gave the conjugate with a high modification ratio (4.6 molecules per STI), high yield (95%), and satisfactory activity recovery (63%). Chemical modification of STI was also carried out with activated polyethylene glycol (PEG) for comparison. The STI-PEG conjugate was obtained in a satisfactory yield (96%) and modification degree (5.8 molecules per STI), but the remaining activity was considerably lower (34%). Thus, conjugation of protein with dextran by the periodate oxidation method is suggested to be preferable for preparing a protein-carrier system without significant diminution of its biological activity.

Carbodiimides↗

PubMed1989

Control of pharmaceutical properties of soybean trypsin inhibitor by conjugation with dextran. II: Biopharmaceutical and pharmacological properties.

Biopharmaceutical and pharmacological properties of the Kunitz-type soybean trypsin inhibitor (STI)-dextran conjugate (STI-D) were studied. Dextran having a molecular weight of approximately 10,000 was covalently attached to the STI molecule by periodate oxidation. The STI-polyethylene glycol (PEG) conjugate (STI-PEG) was also tested for comparison. After iv injection to mice, native STI showed rapid elimination of activity from plasma (t 1/2 = 2 min), and approximately 60% of the dose was excreted in urine within 1 h after injection. On the other hand, STI-D was slowly cleared from plasma and its urinary excretion was restricted. The STI-PEG conjugate showed a pharmacokinetic behavior similar to that of STI-D. Pharmacological activities of native and modified STI were evaluated by two animal experimental models; that is, trypsin-induced shock in mice and acute pancreatitis in rats. In mice, shock induced by iv injection of trypsin was inhibited by the iv pretreatment with native STI, but the effect was observed for only 1 h. The STI-D conjugate showed a superior inhibitory effect on trypsin-induced shock to that of STI alone at the same dose, and this effect continued for 5 h. A similar effect was also observed in mice given an iv injection of STI-PEG. In rats with acute pancreatitis, no significant therapeutic effect was shown by the iv treatment with native STI, as well as saline treatment. On the other hand, the iv treatment with STI-D at the same dose as STI lowered the mortality of the rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1989

The effect of immunization with protein-hapten conjugate on the intestinal uptake of p-aminobenzoic acid as a hapten.

Intestinal uptake of p-aminobenzoic acid was examined by means of an in vitro everted sac technique in rats immunized with ovalbumin-p-aminobenzoic acid conjugate. A dose-dependent and antigen-specific decrease in the serosal transfer of p-aminobenzoic acid was observed in rats immunized 6 times with protein-hapten conjugate compared with the control. There was a significant increase in the recovery of p-acetamidobenzoic acid, a metabolite of p-aminobenzoic acid, in mucosal fluid, tissue, and serosal fluid in the jejunum. In the case of ileum, increase of p-acetamidobenzoic acid was observed in mucosal fluid. However, there was no significant effect in the ileal p-acetamidobenzoic acid in tissue and serosal fluid between immunized and non-immunized rats. To examine the increased metabolism of immunized rats, N-acetyltransferase activity of the small intestinal mucosa was examined. There was a significant increase in mucosal N-acetyltransferase activity in immunized rats compared with the control animals. These observations suggested that the mucosal immune system may play an important role in regulating the intestinal uptake of the low molecular weight compounds.

4-Aminobenzoic Acid↗

PubMed1989

Statistical moment analysis of hepatobiliary transport of phenol red in the perfused rat liver.

A new experimental system was applied to study hepatobiliary transport of drugs. Rat livers were perfused using a single-pass technique, and phenol red was momentarily introduced to this system from the portal side. Outflow dilution patterns of phenol red were analyzed using statistical moment theory, and kinetic parameters of hepatic distribution and elimination of phenol red were calculated from moments, namely, the hepatic extraction ratio (Ei) and elimination rate constant (kel,i). A larger distribution volume (Vi) was obtained for phenol red than for 131I-human serum albumin (HSA) and 51Cr-red blood cells (RBC), indicating its extravascular diffusivity. The biliary excretion of conjugated phenol red was delayed relative to that of the free agent. The larger biliary mean transit time (tbile,conj.) represents the processes of biliary transport and intrahepatic metabolism. Further, the effects of dose and perfusion temperature on the hepatobiliary transport of phenol red were determined. With high doses or low perfusion temperatures (20 and 27 degrees C), Ei, kel,i, and intrinsic clearance (CLint,i) of phenol red and biliary recovery of free and conjugated phenol red (Fbile,free, Fbile,conj) significantly decreased. The temperature-dependent and saturable processes in hepatic uptake, metabolism, and biliary excretion of phenol red were assessable to moment analysis.

Animals↗

PubMed1989

Analysis of drug penetration through the skin by the two-layer skin model.

A diffusion model for the skin penetration of drug in the finite-dose system was developed considering the skin to be composed of two layers, the outermost layer (stratum corneum) and the lower layer (viable epidermis and dermis). Based on this skin model, the Laplace transforms of the equations for the drug amounts in the receptor, the vehicle, and the skin were derived. The penetration profiles of 6-mercaptopurine (6-MP) through the intact and stripped guinea pig skin were obtained from in vitro diffusion experiments. The computer fitting of those profiles to the Laplace-transformed equations by a nonlinear least-squares program based on a fast inverse Laplace transform algorithm [MULTI-(FILT)] gave parameters such as diffusion coefficients of 6-MP and thicknesses of both layers. The mean transit time (MTT) for each diffusion process was defined based on statistical moment concept and calculated using the obtained parameters. Under the present condition, the process to move from the vehicle to the stratum corneum is demonstrated to have the longest mean time in overall processes of 6-MP penetration.

Animals↗

PubMed1989

Sagittal tomography in the supine patient.

The authors have developed a multidirectional tomographic unit to obtain sagittal images with the patient in the supine or prone position. The apparatus is particularly useful for examination of the vertebral column and sella turcica. It can be employed in circular (0 degrees -40 degrees) and spiral (10 degrees -32 degrees) motions. The apparatus provides correct and easy positioning of subjects with easy maintenance of posture. It reduces the distortional effects of respiration and thereby markedly improves reproducibility.

Humans↗