We developed a simple method for the quantification of cystine (disulfide bond) content in hair by measuring the amount of oxidized dithiothreitol (λmax 283 nm) deived from dithiothreitol (DTT) with cystine. Because the cystine content in hair is almost fixed for each animal species, it can be used as a reliable indicator of hair weight. The absorbance (A280, y) of the supernatant of the reaction mixture correlated well with hair weight (mg, x) (y=0.10x+0.06, r=1.00, n=10). Within-run and between-day reproducibilities (C.Vs., %) for the assay were 3.1 and 2.8 (n=5 each), respectively. Hair cystine content (nmol/mg hair, mean±S.D.) in normal volunteers was 903±50.6 (n=10) by the present method and 755±24.9 (n=10) when an amino acid analyzer was used. After assay by our method, the hair sample can be washed, then used repeatedly to assay other analytes. The present method should be useful for assays of analytes present only in small amounts (2-20 mg), without the need for precise weighing of the hair samples.
Enzymatic hydrolyses were described for three variants of glycosidic conjugated bile acids with one β-glucuronidase (Helix pomatia), three β-glucosidase (almonds, sweet almonds, and Escherichia coli), and four β-N-acetylglucosaminidase (Jack beans, bovine kidney, human placenta, and Diplococcus pneumoniae) preparations. The substrates include the β-glucuronide, β-glucoside, and β-N-acetylglucosaminide conjugates of bile acids related to hyodeoxycholic, murideoxycholic, chenodeoxycholic, and ursodeoxycholic acids possessing a sugar moiety at position C-3, C-6 or C-7. The comparative abilities and optimal conditions for the β-glycosidases to catalyze the hydrolyses of the substrates were clarified by changing pHs and incubation times. Hydrolysis rates of the bile acid glycosides with β-glycosidase treatments were influenced by both the source of the enzyme preparations and the conjugated position of a sugar moiety in the substrates, and the 3-glucoside and 3-N-acetylglucosaminide conjugates were usually hydrolyzed more efficiently than their corresponding 6- and 7-analogs. Escherichia coli and jack bean enzymes were chosen to hydrolyse the glucosidic and N-acetylglucosaminidic conjugated bile acids, respectively.
β-Glucuronidases of mammalian tissues metabolized glycyrrhizin (18β-glycyrrhetinic acid, β-D-glucuronyl α-D-glucuronic acid, GL) to glycyrrhetinic acid (GA) via 18β-glycyrrhetinic acid α-D-glucuronic acid (GAMG); they hydrolyzed β-glucuronic acid conjugates better than α-glucuronic acid conjugates. However, human intestinal bacteria directly metabolized GL to GA, and minorly to GA via GAMG. Bacteroides J-37, isolated from human intestinal bacteria, transformed GL or GAMG to GA, but not baicalin; it produced α-glucuroniase, which hydrolyzed the α-linkage of glucuronic acid conjugates. α-Glucuronidase of Bacteroides J-37 hydrolyzed α-glucuronic acid conjugates better than β-glucuronic acid conjugates. β-Glucuronidase from E. coli, a human intestinal bacterium, hydrolyzed baicalin to baicalein, but did not transform GL.
A cytotoxic factor (CF) appeared in murine serum after the intravenous injection of the dehydrogenation polymers (DHPs) of p-coumaric acid (DHP-pCA), caffeic acid (DHP-CA), and ferulic acid (DHP-FA), which are categorized as a class of synthetic lignins. The highest CF activity was observed 15 min after the i.v. injection of DHP-pCA. CF is likely to be cytocidal through an apoptotic mechanism accompanied by nucleosome-sized DNA fragmentation. CF is extractable with aqueous ethanol and highly stable against heat, proteases, and acid/alkali treatments. The ethanol extract showed cytotoxicity toward various cultured cell lines and also ascites carcinoma cells in vivo. The parent molecules DHPs did not show any appreciable cytotoxicity. After the induction of CF activity, the activity quickly diminished and completely disappeared from the blood stream within an hour or so. The cytotoxicity was observed only when the target cells were exposed to CF for longer than 10 h.
Tumor metastasis into distinct organs and tissues, of which many patients with malignancies die, is regulated in multiple steps. Using a murine metastasis model, in which highly metastatic B16-BL6 melanoma cells were inoculated i.v. into syngeneic C57BL/6 mice, the administration of a recombinant human tissue inhibitor of metalloproteinases-2 (r-hTIMP-2) once a day on days -1 to 3 after the implantation significantly inhibited the formation of metastatic foci in the lungs. The antimetastatic effect of r-hTIMP-2 was detected irrespective of administration route [i.v., i.p., s.c., and i.m. routes] and in a dose-dependent manner. The i.m.-injection of r-hTIMP-2 during the early phase after tumor inoculation is suggested to be essential for antimetastasis. In another model using spontaneously metastasing B16-BL6 cells, multiple i.m.-injections of r-hTIMP-2 also resulted in a reduced but not statistically significant number of pulmonary metastases. In addition to these antimetastatic effects, a slight inhibitory effect on tumor cell growth was observed in vitro and in vivo. In conclusion, the antimetastasis by r-hTIMP-2 may be due to inhibition of the degradation of the extracellular matrix by matrix metalloproteinases (MMPs) and, in part, to the suppression of the tumor cell growth.
This report describes the in vitro pharmacological properties of dipotassium (Z)-2-[[5-ethyl-3-[2'(1H-tetrazol-5-yl)biphenyl-4-yl]methyl-1, 3, 4-thiadiazolin-2-ylidene]aminocarbonyl]-1-cyclopentenecarboxylate, called KRH-594, a novel angiotensin II (AII) type 1 (AT1) receptor antagonist. We exposed rabbit aortic rings to KRH-594 (0.1 nM) for increasing contact times and observed an increasing degree of insurmountable suppression of AII-induced contractions. KRH-594 (0.01, 0.1 and 1.0 nM) caused a concentration-related, insurmountable suppression of the AII concentration-response curve. Repeated washing of rabbit aortic rings preincubated with KRH-594 (0.1, 1.0 and 10 nM) slowly reversed the insurmountable suppression. The marked suppression of AII-induced contractions by KRH-594 (0.1 nM) was restored by co-incubation with losartan (100 nM). KRH-594 (10 μM) had no effect on bradykinin-, acetylcholine-, or histamine-induced contractions of guinea pig ileum, demonstrating its high specificity for AT1 receptors. These results demonstrate that KRH-594 is a potent, specific and insurmountable AT1 receptor antagonist. KRH-594 activity in rabbit aorta appears to be that of a slowly reversible (pseudo-irreversible) antagonist.
A conitine administered intraperitoneally (i.p.) produces bradycardia mainly by a central muscarinic action. The involvement of hypothalamic regions in the occurrence of aconitine-induced bradycardia was investigated in hypothalamus-lesioned mice. The lesions were made by passing a direct current (1.5mA, 13s) through a monopolar electrode. The aconitine (30 μg/kg, i.p.)-induced bradycardia was prevented by bilateral lesions of either the whole hypothalamus, except for the lateral hypothalamus area, or the anterior hypothalamus (AH). The bradycardia was not prevented by bilateral lesions of the ventromedial, the paraventricular, the posterior or the lateral hypothalamus regions. Bupivacaine, but not atropine (1 μg, administered into the intact AH) prevented aconitine-induced bradycardia in mice with a contralaterally lesioned AH. Aconitine (0.8 μg) directly administered into the unilateral AH in intact mice caused a late phase and lesser extent of bradycardia. These results suggest that a transmission pathway including the AH contributes to the aconitine-induced bradycardia but does not involve the activation of muscarinic receptors in the AH.
This study was carried out to elucidate the antiinflammatory effect of 70% methanol extract obtained from the dried fruit of Forsythia suspensa VAHL and its active principles. F. suspensa was extracted with 70% methanol and freeze-dried to give a powdered extract. The methanol extract was then dissolved in water and extracted with n-hexane, and the n-hexane fraction was evaporated to dryness under vacuum; the water fraction was freeze-dried to give a powdered extract. The antiinflammatory activity of the extract and fractions was investigated on acetic acid-induced vascular permeability and writhing symptoms in mice, as well as on carrageenin-induced edema and cotton pellet-induced granuloma formation in rats. The methanol extract and the n-hexane fraction (p.o.) showed the antiinflammatory effect and analgesic effect, but the water fraction did not. These results suggested that the antiinflammatory and analgesic activity induced by the methanol extract shifted to the n-hexan fraction and the active principles may be lipophilic compounds.
Eight minor isoflavonoids (3-10) isolated from the knot of Wistaria brachybotrys were tested for their inhibitory effects on Epstein-Barr virus (EBV) activation induced by the tumor promoter, 12-O-tetradecanoyl-phorbol-13-acetate (TPA), in Raji cells as a primary screening test for anti-tumor-promoters (cancer chemopreventive agents), and all the tested compounds showed inhibitory activity. Of these compounds, pendulone (3) was further examined on the cell cycle of Raji cells, and indicated strong inhibition on the effect of the cell cycle induced by TPA. In addition, the compound showed potent anti-tumor-promoting activity for an in vivo two-stage carcinogenesis test of mouse skin using 7, 12-dimethylbenz[a]-anthracene and TPA. Consequently, it suggests that 3 could be a valuable chemopreventive agent in chemical carcinogenesis.
Carboxylesterases (EC 126.96.36.199) from human liver were purified using Q-Sepharose, Sephadex G-150, isoelectrofocusing and Con A-Sepharose. The calculated molecular mass of the pI 5.3 enzyme was 120 kDa and 61 kDa from the results of Sephadex G-150 gel filtration and SDS-polyacrylamide gel electrophoresis (PAGE), respectively, suggesting that this enzyme is a dimer. On the other hand, carboxylesterase pI 4.5, with a molecular mass of 64 kDa, was a monomer. The activities of both enzymes were inhibited by typical serine enzyme inhibitors. Amino acid sequence analysis of the purified enzymes pI 5.3 and 4.5 showed high homology with rabbit carboxylesterase form 1 and 2, respectively. The results also suggested that carboxylesterase pI 5.3 is identical to the deduced amino acid sequence from cDNA for HU1, and that carboxylesterase pI 4.5 is identical to the deduced amino acid sequence from the cDNA registered as human carboxylesterase (hCE-2) in GenBank. We first purified carboxylesterase pI 4.5 and investigated its hydrolytic activity upon various drugs. The two enzymes differed in substrate specificity. Prodrugs of angiotensin-converting enzyme inhibitors, such as delapril and imidapril, were converted to active metabolites by carboxylesterase pI 5.3, but not by carboxylesterase pI 4.5. The hydrolysis velocity of temocapril by carboxylesterase pI 5.3 was 12-fold faster than by carboxylesterase pI 4.5. In contrast, aspirin, oxybutynin and procaine were hydrolyzed by only carboxylesterase pI 4.5. We also found that an amide-linkage in drugs, except for that in aniracetam, was not a good substrate for the two enzymes. Consequently, carboxylesterases pI 5.3 and 4.5 may be involved in the metabolism of various drugs containing an ester-linkage.
It is accepted that some serum components play important roles in enhancing liposome permeability and in facilitating rapid liposome uptake by the mononuclear phagocytic system. In this study we systematically investigated the influence of serum components from different species on complement-mediated immune damage to hydrogenated phosphatidylcholine (HEPC)-based liposomes. Our results demonstrated that when liposomes were incubated with fresh serum from rats or bovines, there was obvious leakage of 5(6)-carboxyfluorescein (CF) from the liposome. However, when liposomes were incubated with fresh serum from humans, rabbits, guinea pigs, mice, and dogs, almost no pronounced leakage from the liposome was observed. These results indicate that the variability of damage to a liposome corresponds to the variability of the animal species from which the serum comes. In addition, leakage of CF from liposomes was completely inhibited by heating at 56°C for 30 min or by treatment with EDTA. However, such leakage was not blocked by treatment with EGTA/Mg2+, suggesting that the mechanism of lysis of liposomes is due to complement activation via the alternative pathway rather than via the classical pathway. Studies on reconstitution and compatibility further confirm that some serum factors (complement activating factors, CAFs) induce the activation of the complement system, ultimately leading to the lysis of the liposomes. However, CAF from different animal species exhibited corresponding species differences. Meanwhile, under the condition of heating and dialysis experiments, it is obvious that the CAF is susceptible to heat and the dialysed serum sustains biological activity to destabilize liposome following dialysis against a buffer with Ca2+ and Mg2+, indicating that the CAF is not a type of low-molecular weight material but a serum protein.
In this study, we investigated a liposomal formulation of dipalmitoylphosphatidylcholine (DPPC) with a soybean-derived sterylglucoside mixture (SG) and cholesterol (Ch) for targeting the liver in mice. We found two distribution profiles of liposomes (reverse-phase evaporation vesicles, REV) in the liver depending on the concentration of Ch and SG in vivo; Ch tends to enhance liposomes containing 10 mol% SG accumulation in the liver, but to decrease those containing 20 mol% SG, and it prolongs the circulation in blood. Dicetylphosphate did not enhance liver targeting by liposomes with SG and Ch. More DPPC/SG/Ch-liposomes (6 : 1 : 3) were significantly taken up by cultivated hepatocytes than DPPC/SG/Ch-liposomes (6 : 0 : 4), suggesting a glucose residue. The optimal composition for the maximal liver targeting was a mixture of 0.2 μm DPPC/SG/Ch-liposomes (REV) at a molar ratio of 6 : 1 : 3. This composition of liposomes was distributed 3 times greater in hepatocytes than non-parenchymal cells 1 h after intravenous injection.
In this sutdy, the transport characteristics of ciprofloxacin (CPFX) were investigated in a LLC-PK1 kidney epithelial cell line. CPFX uptake from the apical medium into LLC-PK1 cells on plastic dishes was shown to be temperature-dependent. Guanidine and cimetidine inhibited the uptake of CPFX, whereas tetraethylammonium chloride (TEA) and N1-methylnicotinamide (NMN) did not. CPFX transport across LLC-PK1 cell monolayers cultured on permeable supports was about 1.8 times larger in the basolateral-to-apical direction than in the apical-to-basolateral direction. Both the basolateral-to-apical and apical-to-basolateral transport of CPFX were inhibited by guanidine, whereas CPFX transport in both directions was not inhibited by TEA, NMN, or cimetidine. The basolateral-to-apical transport of CPFX was sensitive to the pH of the apical medium, and increased in an acidic pH. Enoxacin (ENX) as well as guanidine, inhibited the basolateral-to-apical transport of CPFX, and the inhibitory effect of ENX was sensitive to the pH of the apical side of the monolayers.
A suppository of zonisamide (ZNS) was investigated from the viewpoint of pharmaceutical evaluation, pharmacokinetics and pharmacological effect. Two types of ZNS suppositories were prepared. One used Witepsol (H-15 : S-55=3 : 1) as a lipophilic base and the other polyethylene glycol (PEG, 4000 : 1500=4 : 1) as a hydrophilic base. The in vitro release rate of ZNS from the PEG suppository was significantly rapid compared with that of ZNS from Witepsol. Male Wistar rats were administered ZNS (20 mg/kg) using an intravenous, oral or rectal (PEG or Witepsol) route. The absorption of ZNS from the PEG suppository was more rapid than that of ZNS from the Witepsol suppository or from the oral preparation. The peak plasma concentration (Cmax) after a rectal administration of ZNS with Witepsol or PEG suppository was significantly higher than that after the oral administration of ZNS. However, the bioavailability of the three preparations was approximately 100%. Male ICR mice were administered ZNS (80 mg/kg) using the oral or rectal (PEG or Witepsol) route. A positive correlation was observed between the electroshock seizure (ES) threshold and ZNS concentration in plasma or brain. Further, there was no significant difference in the ES threshold or the ZNS concentration in plasma or brain among the three preparations. These results indicate that a ZNS suppository is a very useful preparation from the viewpoint of both pharmacokinetics and pharmacological action.
We created a predictive model for the area under the concentration versus time curve (AUC) of cyclosporin A (CsA) using routine monitoring results, and examined its clinical utility. Based on 48 clinical time courses accumulated from renal transplant patients, the AUC predictive model was created. An estimate of the AUC0-8 (integrated from time zero to 8 h) was then given as follows : AUC0-8=5673.1×log(TL)+9342.8×log(OB)+64.1×Dprd×869.4×DTK-168.9×HCT-161.2×SCr-11.3×GPT+3.0×PL-588.6×SEX-24794.5. In this model, the AUC0-8(ng·h/ml) is given as a function of the CsA trough levels (TL, ng/ml), obesity (OB, %), daily dose of prednisolone (Dprd, mg/d), donor type of kidney (DTK), hematocrit (HCT, %), serum creatinine (SCr, mg/dl), glutamate-pyruvate transaminase activity (GPT, IU/l), plasma lipids (PL, mg/dl) and sex distinction (SEX). The Statistical significance of this multiple regression was p<0.00001 (R2=0.862, n=48), and the day after transplantation, neither the administered oral dose of CsA, or the patient's age had any contribution to the regression. The predictive performance of this model was almost equal to that of the existing method which used 3-point data on the concentration versus time curve. In clinical adaptation for renal transplant patients, the steady-state concentration of CsA (Css) based on the AUC0-8 predictive model was significantly decreased during acute gastroenteritis or before acute rejection, whereas nephrotoxicity was increased, even though CsA trough levels were within a normal therapeutic range (100-200 ng/ml). These findings suggest that the created AUC0-8 predictive model using routine monitoring results, i.e., the trough level of CsA, biochemical tests, a daily dose of predorinsolone (PRD), and basic patient information, is convenient as a monitoring device for CsA therapy, and is satisfactory in clinical practice.
A spatiotemporal ESR-CT study, rapid three dimensional ESR imaging by which distribution and metabolism of radicals in a small region in a living body can be followed, was carried out by intravenously administering spin-labeled polysaccharides to mice. The in vivo lifetime of spin-labeled hydroxyethylstarch (TEMPO-HES) was shorter than that of spin-labeled dextran (TEMPO-DX), suggesting that the clearance of their spins depended on the stability of the polymer chains to the hydrolysis. Spatiotemporal image at the kidney domain of a mouse showed that low molecular weight TEMPO-DX was excreted into the kidney and then was transferred to the bladder. Time dependence of the ESR intensity of TEMPO-HES at certain points in the liver domain had a maximum showing that TEMPO-HES was intaken into the liver and then was decomposed there by the metabolism, but the rate of decrease in the intensity was different in each part in the liver because of the difference in metabolic function. The rate of decrease of TEMPO-DX in the blood was slowed by the prior administration of dextran, meaning that the intake of TEMPO-DX into the liver from the blood was suppressed by the dextran.
The riboflavin sensitized oxidation of cysteine under an aerobic condition was investigated. The effects of various scavengers, such as superoxide dismutase, catalase, mannitol, sodium azide and potassium ferrocyanide (an electron donor), on the photooxidation were determined. A reaction mechanism involving the superoxide anion is proposed for the photooxidation of cysteine to cysteic acid.
Two photoaffinity-labeling probes for retinoic acid receptor (RAR) α, 4-[(3-(3-(trifluoromethyl)-3H-diazirin-3-yl)phenyl)carboxamido]benzoic acid (3DIAM) and its para-isomer (4DIAM), were designed and synthesized. Both compounds possess high affinity for recombinant RARα (MBP-RARα/E) and bind covalently to its cognate ligand-binding site. The labeled site of MBP-RARα/E with 3DIAM was determined, by the endoproteinase combination method, to be located in helix 11 of the ligand-binding domain of RARα, which is the position at which the ligand is considered to bind, on the basis of the reported crystal structure of the retinoic acid/RARγ complex.
To characterize flavin-containing monooxygenase (FMO) in brain microsomes of rat, mouse, hamster, guinea pig and rabbit, profiles of its enzyme activities were investigated by HPLC-fluorometrical assay using benzydamine (BZY) as a substrate. The optimum pH of BZY N-oxidation activity in brain microsomes from rat, mouse, hamster or guinea pig was between 8.5 and 9, though that of the rabbit brain microsomes was near 10.0. The activities were thermally unstable in brain microsomes from all the species examined in the absence of NADPH, but the activity in rabbit brain microsomes was rather thermostable in the presence of NADPH. The activity in rabbit brain microsomes was depressed in the presence of 5 mM n-octylamine. In the presence of MnCl2, the enzyme activity in rabbit brain microsomes was markedly decreased. ZnCl2 markedly decreased the enzyme activities in brain microsomes from rat, mouse and rabbit. It was concluded that BZY N-oxidation activity in brain microsomes from rat, mouse, hamster and guinea pig are similar in enzymatic properties but different from the activity of that rabbit. These results suggest that common FMO isoform(s) other than FMO-4 might exist in the brains of the four rodent species tested.
Rat cytokine-induced neutrophil chemoattractants (CINC)-1, -2α, -2β and -3 belong to α-chemokines and are known to be potent chemoattractants for rat neutrophils in vivo and in vitro. In this study, the abilities of CINCs to affect several functions of rat neutrophils are estimated. All CINCs at a concentration of 10-8 M induced the polarization of rat neutrophils. The adhesion of each CINC-treated neutrophil to fibrinogen significantly increased, reaching a maximal adhesion at 10-8 M of each CINC. The CINCs enhanced the phagocytosis of heat-killed yeast cells by neutrophils in a dose-dependent manner. In contrast, CINCs did not induce the production of reactive nitrogen intermediates. The results suggest that CINCs play a significant role in neutrophil infiltration and phagocytosis at inflammatory sites in rats.
We examined individual variations in acetohexamide reductase activities in liver microsomes and cytosol of rats. Large differences among individuals were observed for acetohexamide reductase activity in liver microsomes of male Fischer-344 (Fischer), Sprague-Dawley (SD) and Wistar rats at 9 weeks of age, except in the Wistar-Imamichi (Wistar-IM) strain. These four strains of female rats did not exhibit any microsomal enzyme activity. Although acetohexamide reductase activities were fully detectable in liver cytosols from all the strains of male and female rats, there was neither strain-related difference nor considerable individual variation in the cytosolic enzyme activity. In liver microsomes of male Fischer rats at 4 weeks of age, acetohexamide reductase activity was not detectable. The microsomal enzyme activity in male Fischer rats markedly increased at 6 weeks of age to approach the levels at 9 and 12 weeks of age, with large individual variations.
All of the vanadate and vanadyl compounds tested in this study showed potent antibacterial activity against Streptococcus pneumoniae : the MIC (minimum inhibitory concentration) values of the vanadium compounds were 4-32 μg/ml, while the MIC values of tungstates and molybdates were 128->8000 μg/ml. Scanning electron microscopy showed the elongation of S. pneumoniae strains under low concentrations (<MIC) of vanadium compounds such as (tert-BuNH3)4[V4O12] (1), (tert-BuNH3)6[V10O28] (2), Na3VO4 (7) and VOSO4 (8). The vanadium compounds non-selectively inhibited the incorporation of thymidine, uridine, leucine and glucose into the cells of S. pneumoniae and led to an efflux of potassium ions from the cells. It implies that the vanadium compounds interfere in or on the cell membrane with the transport of substrates and ions through the cell membrane, resulting in antibacterial activity against S. pneumoniae cells.
We investigated the effect of acute renal failure on the neurotoxicity of enoxacin (ENX) in rats. Experimental acute renal failure was produced by bilateral ureteral ligation. ENX was intravenously infused to ureter ligated (UL) and control rats, and its concentration in plasma, brain and cerebrospinal fluid (CSF) was compared. Plasma concentration of ENX increased rapidly in UL rats as compared with control rats. Brain/plasma concentration ratio (Kp)-time profile of ENX was similar in UL and control rats. Brain concentration of ENX at the occurrence of convulsion did not depend on the infusion rate, suggesting that in the brain tissue it equilibrates rapidly with the site of action for clonic convulsion. Brain concentration of ENX in UL rats at the occurrence of clonic convulsion was lower than that in control rats. A similar tendency was also observed with CSF concentration. In conclusion, the potentiation of neurotoxicity of ENX with acute renal failure may be caused by not only decreased capability for renal elimination of ENX but also increased sensitivity to convulsant activity of ENX in the central nervous system.
The inhibitory effect of acyclothymidine[AcyT, 5-methyl-1-(2'-hydroxyethoxymethyl) uracil], a potent pyrimidine nucleoside phosphorylase (PyNPase) inhibitor, on 5'-deoxy-5-fluorouridine (5'-DFUR) phosphorolysis in human and mouse tumor cell homogenates was measured. Competitive inhibition was observed in MKN-74 and Lewis lung carcinoma (LLC), whereas non-competitive inhibition was observed in HeLa. The strength of the inhibitory effect by AcyT showed the following pattern : HeLa<human normal intestine<mouse normal intestine<Colon 26<LLC<MKN-74<DLD-1. From the kinetic parameter obtained, we simulated the inhibitory effect of AcyT on 5'-DFUR phosphorolysis in tumor cells and the intestine. These data indicated that AcyT was more sensitive in normal mouse intestine than in Colon 26 and LLC, and that orally administered AcyT can reduce the intestinal toxicity of 5'-DFUR without reducing the antitumor effect in the mouse. The present finding may have an important implication for attempts to introduce AcyT, a potent PyNPase inhibitor, into the clinic.
The effect of acute renal failure on the pharmacokinetics concerning the cerebrospinal fluid (CSF) distribution of iomeprol, a nonionic contrast agent, was studied. The concentrations of iomeprol in the plasma and CSF were measured after intravenous (i.v.) administration at the dose of 50 or 500 mg/kg body weight. The time courses of plasma and CSF concentration were linear within the dose studied. Influx and efflux clearances estimated by simultaneous fitting were 4.6×10-5 ml/min and 8.8×10-4 ml/min, respectively, which suggested that the distribution of iomeprol to CSF was low and linear. The distribution volume at steady state was 300-500 ml/kg, suggesting that iomeprol was readily distributed to the extracellular space but hardly distributed to the intercellular space. Total body clearance (9-13 ml/min/kg) indicated that iomeprol was mainly excreted by glomerular filtration. In the rat with acute renal failure induced by ligating the binary ureters, the concentration of iomeprol in CSF after i.v. administration of 500 mg/kg dose was much higher than that in the intact rat according to the delay of elimination from plasma (CLtot=0.07 ml/min/kg). However, the time course of iomeprol concentration in CSF was predictable using the values of the influx clearance to CSF and the efflux clearance from CSF determined by intact rats. In conclusion, renal failure is one risk factor for central nervous system toxicity because of decreased total body clearance, while acute renal failure may not affect the transport of iomeprol to CSF.