An automated system for HPLC-fluorometry of serum guanidino compounds was constructed. This system accomplished simultaneous removal of protein and uremic fluorescences, abundant in the sera of uremic patients, which interfere with the fluorometric assay. This system was applied to the detailed elucidation of the behavior of guanidinosuccinic acid and methylguanidine during and after hemodialysis therapy (HD). The uremic patients who are capable of excreting urine even under hemodialysis therapy showed low serum guanidinosuccinic acid and methylguanidine levels. The prolongation of the interval between HD for one of the patients capable of excreting urine was examined. The levels of guanidinosuccinic acid and methylguanidine did not significantly increase and no hazardous effect was observed by 2 d of prolongation.
Ultra-filtrable and macromolecule-bound polyamines in rat liver homogenates, made without buffer, were determined, using Potter-Elvehjem homogenizer and commercially available, pressure-aided ultrafiltration device with a membrane pore size that allows passage of particles of molecular weight no larger than 5000. About 90% of polyamines in the liver were shown to be equilibrated with externally added 15N-labeled polyamines, based on the difference in the ratio of the natural to 15N-labeled polyamine in the liver homogenate and the ultrafiltrate. The entire amount of ultrafiltrate in the homogenized liver, required for calculation of the amounts of ultra-filtrable and macromolecule-bound polyamines, was estimated to be about 0.25 g in one gram of homogenate, using a limited dilution curve of spermine in the ultrafiltrate with phosphate buffered saline and distilled water. With this value, ultra-filtrable polyamines in normal rat liver homogenate were calculated as about 25%, 8%, and 2% of the total amount of putrescine, spermidine, and spermine, respectively. The method was then used to measure ultra-filtrable and macromolecule-bound polyamines in regenerating rat liver homogenates, to examine possible changes of polyamines during cell growth. The method was also applied to measure other ultra-filtrable compounds such as amino acids and inorganic ions in rat liver homogenate.
We investigated the effects of ketoconazole (KCZ) and fluconazole (FCZ) on rat liver microsomal nevirapine (NVP) metabolism in vitro and on NVP plasma profiles in vivo in order to determine whether the in vivo drug interactions could predicted quantitatively from the in vitro data. The Ki values of KCZ and FCZ for NVP 12-hydroxylation were 1.59 μM and 11.5 μM, respectively, indicating that KCZ inhibited this activity more strongly than FCZ in vitro. In contrast, FCZ orally pre-administered at 20 mg/kg to rats increased the area under the plasma concentration-time curve (AUC) of NVP 7.4-fold, whereas KCZ increased it 2.1-fold, compared to the vehicle. We next investigated the inhibitory potency and unbound concentrations of KCZ and FCZ in microsomal mixtures with or without rat albumin. In the presence of albumin, the inhibition by KCZ was greatly decreased. Further, the unbound fraction of KCZ was decreased dramatically to around 3%, whereas more than 90% of FCZ remained in unbound form. When the increase in the AUC for NVP was calculated based on the concentrations of unbound inhibitors in the portal vein, good agreement with the observed in vivo values was obtained.
Few reports are available about tissue concentration of amoxicillin. The techniques used to measure tissue concentration usually require rupture and are expensive. The objective of the present study is to assess the utility of an animal model to predict tissue concentration of amoxicillin using induced granulomatous tissue. We used 160 rats with four polyurethane sponges previously implanted in their backs. At 7, 14, 21 and 28 d after sponge introduction, groups of eight animals each received 3.5, 7.0, 40.0 or 80.0 mg/kg of amoxicillin (p.o.) or 1 ml of 0.9% NaCl solution (control group). One hour after drug administration, 10 μl of serum and granulomatous tissue were obtained. Tissue and serum were placed on different plates containing Mueller Hinton agar inoculated with 108 cfu (colony forming unit) of Staphylococcus aureus (ATCC 25923), and the diameters of the inhibition zones were measured after 18 h of incubation. Analysis of variance showed no statistically significant differences (p>0.05) among time periods for the same dose of amoxicillin. These results suggest that the pharmacokinetics of amoxicillin did not change in relation to the development of granulomatous tissue; therefore this method is valid to measure the tissue concentration of amoxicillin.
Deoxynybomycin was identified as an inducer of p21 the/WAF1 gene following screening using a reporter, p21/luciferase. The present study examined its anti-proliferative effect on human tumor cell lines. Deoxynybomycin selectively inhibited growth of human osteoblastic sarcoma Saos-2, gastric cancer TMK-1, and monocytic leukemia THP-1 cells, but did not affect survival of normal human fibroblasts at doses up to 5 μg/ml. Results from an assay system using a panel of 39 human cancer cell lines indicated that deoxynybomycin has selective cytotoxic activity against lung carcinoma cell lines. Deoxynybomycin induced apoptosis in Saos-2, TMK-1, and THP-1 cells as revealed by DNA fragmentation and TUNEL assays. It inhibited topoisomerase I but not topoisomerase II. These results suggest that deoxynybomycin may be useful in cancer chemothrerapy.
The effect of sesamin, a lignan from sesame oil, on altered vasodilator and vasoconstrictor responses in aortic rings from deoxycorticosterone acetate (DOCA)-salt-induced hypertensive rats, were examined. The systolic blood pressure after 5-weeks DOCA-salt treatment was 195.0±2.8 mmHg, which was much higher than that of sham-operated control animals (131.2±2.4 mmHg). Sesamin feeding significantly suppressed the development of this hypertension (167.1±8.6 mmHg). Acetylcholine (ACh)-induced endothelium-dependent relaxation of aortic rings was markedly decreased in the DOCA-salt hypertensive animals, compared with cases of the control (pD2, 7.0±0.1; maximal response, 64.8±3.4% versus pD2, 7.7±0.2; maximal response, 93.3±2.7%). There changes were partially but significantly improved by the sesamin feeding. This improvement seems to be related to a nitric oxide (NO)-dependent component of ACh-induced action, because sesamin feeding did not affect the responses to ACh in the presence of NO synthase inhibitor. A spontaneous NO releaser (±)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide (NOR 3) which exerts endothelium-independent vasodilatation, produced the same patterns of responses as those observed with ACh in cases of DOCA-salt treatment and sesamin feeding. Phenylephirine-induced vasoconstriction was enhanced by the DOCA-salt treatment, both in preparations with and without endothelium, but these enhancements were almost completely normalized by sesamin feeding. Thus, dietary sesamin could efficiently improve the abnormal vasodilator and vasoconstrictor responses in DOCA-salt hypertensive animals. These effects may contribute to the antihypertensive activity of sesamin.
We compared urinary protein C inhibitor (uPCI) with low molecular weight heparin (LMWH) in terms of the effect on the pathophysiology of disseminated intravasscular coagulation (DIC), such as hypercoagulation, induction of secondary fibrinolysis and organ failure, using lipopolysaccharide (LPS)-induced DIC in rats. The uPCI (0.5 and 1.0mg/kg) administration significantly inhibited both the decrease in fibrinogen level and the increase in fibrin/fibrinogen degradation products (FDP) level, and the effects compared favorably with those of LMWH (100 and 200 IU/kg). Both uPCI (0.5 and 1.0 mg/kg) and a low dose of LMHW also inhibited the increases in the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), thrombin, and plasma kallikrein equally, but a high dose of LMWH did not inhibit the changes in those parameters. Furthermore, uPCI dose-dependently prevented the prolongation of activated partial thromboplastin time (APTT), while LMWH excessively prolonged APTT at a high dose.These results suggest that the preventive effect of uPCI on the pathophysiology of DIC compares favorably with that of LMWH, including the lack of a hemorrhagic reaction in contrast to LMWH.
When L-glutamate (150 μM) was added to rat cortical astrocyte cultures and incubated for 1-3h, the extracellular L-glutamate concentration declined with time. The time-dependent decline of extracellular L-glutamate concentration was due to the uptake of L-glutamate by astrocytes. The clearance of extracellular L-glutamate by astrocytes was partly slowed down by replacing NaCl with choline chloride or LiCl in the extracellular medium or by adding KCl, and was completely blocked by replacing NaCl with KCl. Furthermore, the L-glutamate clearance was blocked by Na+-K+ pump inhibitors, ouabain and vanadate, but was not affected by Na+ channel modulators nor by K+ channel blockers. These results suggest that the clearance of extracellular L-glutamate by astrocytes is dependent on both Na+ and K+ gradients across the plasma membrane, and that the Na+-K+ pump plays a role in the regulation of L-glutamate clearance.
The effects of Fujibitol, a preparation of crude drugs in wide clinical use for treatment of chronic rhinitis and empyema, on experimental allergic rhinitis in rats were studied. Fujibitol inhibited nasal allergic symptoms, i.e. sneezing and nasal rubbing, induced by antigen in sensitized animals. An increase in dye leakage into the nasal cavity induced by antigen was also inhibited by Fujibitol. On the other hand, no inhibitory effects were observed on either the nasal allergic symptoms or increase in dye leakage into the nasal cavity induced by histamine. However, Fujibitol was effective in inhibiting histamine release from the nasal cavity induced by antigen. Oxatomide used as positive control drug showed potent inhibitory effects on nasal symptoms and dye leakage into the nasal cavity induced by histamine and antigen. These results suggested that Fujibitol showed a remarkable protective effect against experimental rhinitis induced by antigen via inhibition of histamine release from the nasal cavity.
To gain insight into the binding aspects of 6α- and 6β-methylandrostenediones (1 and 2), potent competitive inhibitors and effective substrates of aromatase, at the active site of the enzyme, we synthesized their 19-hydroxy and 19-oxo derivatives to determine their inhibition of aromatase activity as well as their aromatization rates in human placental microsomes. The 6β- and 6α-methyl-19-ols 12 and 13 were produced from 19-(tert-butyl-dimethylsiloxy)androstenedione (6) in 6 steps in which the Grignard reaction of 5α, 6α-epoxy steroid 8 with CH3MgBr was employed as a key reaction. Oxidation of the 19-ols 12 and 13 yielded the corresponding 19-als 14 and 15. The 6α-methyl steroids 13 and 15 were good competitive inhibitors of aromatase (Ki≤100 nM), and their aromatization rates obtained by gas chromatography-mass spectrometric analysis were 110 and 205pmol/min/mg protein, respectively. In contrast, the 6β-methyl isomers 12 and 14 were non-competitive inhibitors, with Ki values of more than 500 nM, and they were aromatized at rates of 16 and 20 pmol/min/mg protein, respectively. These results reveal that there is a marked difference in binding to the active site between the 19-oxygenated 6α-methyl and 6β-methyl inhibitors where the binding manner of the 6α-steroids, rather than the 6β-isomers, is suitable as a substrate for aromatase.
In a previous study, we demonstrated that the intake of mulberry leaves or their 1-butanol extract (MLBE) reduced the concentration of serum lipids and atheromatous thickening of arterial intima in hypercholesterolemic rabbits. In the present study, we investigated the antioxidative activity of MLBE and isoquercitrin, the main component of MLBE. First, we determined the effect on a stable radical agent, finding that quercetin, isoquercitrin and MLBE scavenged the DPPH radical. We then determined the copper-induced oxidative modification of rabbit and human low-density lipoprotein (LDL). Oxidation of LDL was spectrophotometrically monitored by changes in absorbance at 234 nm accompanied by the formation of conjugated dienes, and measured the formation of thiobarbituric acid reacting substances (TBARS). Quercetin, an aglycone of isoquercitrin, inhibited the formation of conjugated dienes and TBARS by copper-induced oxidative modification of rabbit and human LDLs. MLBE and isoquercitrin also inhibited the oxidation of LDL. These results indicate that mulberry leaves inhibit the oxidative modification of LDL and suggest that mulberry leaves may had prevent atherosclerosis.
Twenty-nine flavonoids and six hydrolyzable tannins were studied for their inhibitory activity against human immunodeficiency virus (HIV)-1 protease using fluorescence and HPLC assays. Among the flavonoids, flavones, flavanones, flavonols, catechols and chalcones, the flavonols were the most active category while flavanones and catechols displayed low activity. Quercetin was the most potent inhibitor of the target enzyme with an IC50 value of 58.8 μM, while butein and luteolin showed moderate activity. Of the hydrolyzable tannins tested, three ellagitannins which contain a hexahydroxydiphenoyl (HHDP) unit linked to the O-3 and O-6 positions of the sugar, were found to strongly inhibit HIV-1 protease. The IC50 values of corilagin and repandusinic acid on HIV-1 protease were 20.7 and 12.5 μM, respectively.
Grepafloxacin (GPFX) is a synthetic new quinolone antimicrobial agent that possesses an extensive tissue distribution and exhibits a strong antibacterial activity in vivo. In this study, the tissue distribution characteristics of GPFX were examined using tissue concentration-time profiles following intravenous administration to rats. Subsequently, the pharmacokinetics of GPFX were analyzed based on the physiological pharmacokinetic model. The tissue-to-plasma partition coefficients (Kp) of GPFX in rats were high in all tissues except brain. A pharmacokinetic model for rabbits, monkeys and dogs was constructed using the tissue-to-plasma free concentration ratio (Kp, f) of GPFX in rats to simulate the GPFX concentration-time profile in plasma following intravenous administration of GPFX to each animal. The calculation-derived concentrations correlated well with the experimentally-derived data, suggesting that there are no interspecies differences in the high tissue distribution characteristics of GPFX. The clearance rates of GPFX in humans were predicted from the pharmacokinetic parameters of rats, rabbits, monkeys and dogs by an animal scale-up method and a pharmacokinetic model for humans was constructed. The GPFX concentration-time profiles in plasma, following oral administration of GPFX to humans, were predicted within 0.5-1.0 h of mean absorption time and the calculation-derived results were in good agreement with the experimental data. Thus, it is suggested that the concentration-time profile in plasma and all human organs can be predicted from the pharmacokinetic data of animals.
The inhibitory effects of natural and synthetic inhibitors on the intestinal membrane-bound hydrolase, α-glucosidase (AGH), were evaluated by using an immobilized cyanogen bromide-activated Sepharose 4B support. Immobilized AGH (iAGH) inhibition study by synthetic inhibitors (acarbose and voglibose) revealed that the magnitude of inhibition differed from that in the free AGH (fAGH) study : IC50 value of acarbose in iAGH-maltase assay system, 340-430 nM; fAGH, 11 nM. iAGH-maltase inhibition by both inhibitors was influenced by blocking reagents with different functional groups (COOH, OH, CH3, and NH2 groups). On the other hand, significant iAGH-sucrase inhibitory activity was observed only when using the negatively charged support induced by 0.1 M β-alanine. The Km values obtained in the iAGH assay system were similar to those from the fAGH method. With natural inhibitors, the iAGH-sucrase inhibitory activity of D-xylose, with in vivo glucose suppression, increased twice compared to that in fAGH. Green tea extract gave almost the same inhibition for both AGH assay systems.
A simple and efficient method for the separation of phosphatidylinositol 4-phosphate (PI 4-P) from phosphatidylinositol (PI) and phosphatidylserine (PS) is described. A mixture of PI, PI 4-P and PS was injected onto a Sep-Pak C18 cartridge. PI and PS were flushed through the cartridge with solvent 1 [methanol-chloroform (3 : 1)] while PI 4-P remained in it. Then the cartridge was inverted, and PI 4-P was eluted backward with solvent 2 [chloroform-methanol-0.5 M aqueous ammonium hydroxide (9 : 7 : 2)].
Thiopurine methyltransferase (TPMT) catalyzes the metabolism of important drugs such as 6-mercaptopurine, 6-thioguanine, and azathioprine. The identification and frequency distributions of several variant TPMT alleles (TPMT*2-*8) have been described recently in many ethnic groups. We have recently demonstrated that TPMT*3C is the most common allele in Japanese subjects; however, it remains to be elucidated whether TPMT*4-*8 variants also exist in Japanese subjects. To detect polymorphisms in the TPMT gene (TPMT*4-*8), we have developed a mismatch polymerase chain reaction and restriction fragment length polymorphism method and conducted a population study of Japanese subjects. Genotyping of these variant forms was carried out in 192 Japanese healthy volunteers. The TPMT*4, TPMT*5, TPMT*6, TPMT*7, and TPMT*8 variants were not detected in any of the samples analyzed. This study provides the first analysis of the TPMT*4-*8 variants in a sample of the Japanese population and indicates that TPMT*4-*8 variants do not occur or are rare alleles in this population.
Superoxide anion (O2-) production after very low-dose in vivo irradiation (4cGy) was examined in resident peritoneal macrophages. The level of production rapidly increased following treatment with the PKC activator, phorbol 12-myristate 13-acetate (PMA), but no further enhancement by low-dose in vivo irradiation was observed. On the other hand, treatment with zymosan A gradually induced O2- production, which was further increased in low-dose in vivo irradiated macrophages. The amounts of phagocytosis of zymosan A were not changed by in vivo irradiation. This indicated that the enhancement of O2- production was not due to an increase in phagocytotic activity by low-dose in vivo irradiation. Our results show that low-dose in vivo irradiation induces production of reactive oxygen species by macrophages, not only nitric oxide as reported in our previous paper but also O2-. This may contribute to the increase of cytolytic activity of macrophages after low-dose in vivo irradiation.
A high affinity nerve growth factor (NGF) receptor, tropomyosin-receptor kinase (TrkA), is visualized by expression of TrkA conjugated with cyan fluorescent protein (CFP) in PC12 cells. TrkA was distributed on the plasma membrane of PC12 cells almost uniformly in both differentiated cells and undifferentiated cells. NGF induced differentiation of PC12 cells transfected with TrkA-CFP normally as wild cells without transfection and the expression of TrkA was observed on the entire cell membrane which surrounds the cell body, axons and growth cones. Interestingly, TrkA-CFP was also present on the membrane of filopodia sticking out from the axon and growth cone. In the axonal region, transporting vesicles of TrkA with diameters ranging from 0.5 to 1.5 μm were observed. Some of these vesicles showed net directional movement along the axon in both directions, anterograde and retrograde. The mean velocity of anterograde and retrograde transport was 0.2±0.03 and 0.3±0.05 μm/s (mean±S.E.), respectively. Some vesicles moving anterogradely changed their direction occasionally although the net transport was anterograde. On the other hand, vesicles moving retrogradely seldom switched their direction in spite of occasional stops. These results demonstrated that the behavior of TrkA transporting vesicles in axons of PC12 cells was similar to that observed in the primary culture of sympathetic or sensory neuron. Therefore, it is suggested that the PC12 cell transfected with fluorescent protein-conjugated TrkA is a useful model for studying the signal transduction of NGF.
We examined the effect of cytochalasin B (CB) or granulocyte colony stimulating factor (GCSF) on superoxide radical (O2-) production of neutrophils by phorbor myristate acetate (PMA)-stimulation. It was observed that O2- generation of intact and GCSF-treated neutrophils by PMA-stimulation showed a lag during the early stage, and was largely inhibited by 1-(5-isoquinoline-sulfonyl)-3-methyl-piperazine (200 μM) or GF109203X (GFX) (0.2 μM), but not by ethanol (1%) and wortmannin (100 nM). In contrast, O2- generation of CB-pretreated neutrophils by PMA-stimulation did not show a lag, but was less than that of intact cells, and was only minimally depressed by the above inhibitors, but was markedly depressed by the simultaneous addition of GFX and ethanol or GFX and wortmannin. Although translocation of p47phox and p67phox to the membrane fraction by PMA-stimulation of intact and GCSF-treated neutrophils occurred in parallel with O2- production, that of CB-treated neutrophils by PMA-stimulation was not always proportional to O2- production. These findings suggest that pretreatment of neutrophils with CB dramatically alters the PMA response of the cells; that is, the protein kinase C-dependent pathway is largely depressed, and a phospholipase D-dependent one for NADPH oxidase activation appears in CB-treated cells.
Inhibitory effects of a newly synthesized 5-HT2 receptor antagonist, AT-1015 (N-[2-[4-(5H-dibenzo[a, d]cyclohepten-5-ylidene)piperidino]ethyl]-1-formyl-4-piperidinecarboxamide monohydrochloride monohydrate) on contraction and relaxation of coronary arteries of pig hearts mediated by 5-HT2 subtypes were evaluated and these results were compared with those of ketanserin. Contraction and relaxation were determined by adding 5-HT or α-methylserotonin (α-Me-5-HT) as agonists. Although ketanserin induced rightward shifts of contraction, AT-1015 inhibited the maximal response. In addition, ketanserin inhibited relaxation induced by high concentration of agonists, but there were no inhibitory effects of AT-1015 on relaxation. Thus, these results suggest that AT-1015 is a strong non-competitive 5-HT2 antagonist in porcine coronary arteries and that this drug clearly exhibited different effects on the contraction and relaxation of coronary arteries of pig hearts from those of ketanserin.
The vomeronasal organs of female Wistar rats after the intraperitoneal administration of ketanserin and propranolol prior to sacrifice were exposed to sprayed urine of male Wistar rats. To explore the effects of these antagonists, we studied Fos-immunoreactive (Fos-ir) structures, which correlate with cellular activity, in the accessory olfactory bulb of female rats after the vomeronasal organ was exposed to urine. After the administration of 3 mg/kg ketanserin, the expression of Fos-ir cells in the periglomerular cell layer in response to male Wistar urine was inhibited, while that in the mitral/tufted cell and granule cell layers was not changed. The administration of 20 mg/kg propranolol inhibited the expression of Fos-ir cells in all three layers. These results suggest that serotonin and noradrenaline are likely involved in the modulation of the expression of Fos-ir cells in response to the urine in the accessory olfactory bulb.
A specific binding protein for 12-O-tetradecanoylphorbol 13-acetate (TPA), different from protein kinase C (PKC) and histone H1, was purified from HeLa cell extract by the use of affinity gel pendanted with phorbol ester (TPA-GEL). The purified binding protein was identified as protein disulfide isomerase (PDI, EC 18.104.22.168) by peptide sequence analysis. The dissociation constants (Kd's) of TPA to PDI, histone H1 and PKCα were determined to be 1.03×10-6M, 5.70×10-7M, and 4.00×10-7M, respectively, by the surface plasmon resonance (SPR) method. TPA moderately inhibited PDI activity assessed in terms of reactivation of denatured RNase A.
(-)-Multiflorine (1), which was isolated from leguminous plants, produced a hypoglycemic effect when administered to mice with streptozotocin-induced diabetes. (-)-Multiflorine has an enaminone type conjugation on the A-ring, which is unusual in lupine alkaloids. Proceeding on the assumption that the A-B ring is responsible for the activity, several compounds bearing quinolizidin-2-one were synthesized and their hypoglycemic effects were examined. The hypoglycemic effect of (7R*, 9aS*)-7-phenyl-octahydroquinolizin-2-one was approximately 4 times stronger than that of (-)-multiflorine measured by oral glucose tolerance test in normal mice. This result indicates that compounds possessing the quinolizidin-2-one ring system as the basic structure may be possible lead compounds for a new type of diabetes drug.
As a part of our studies of hepatoprotective drugs, we prepared kaikasaponin I (2), sophoradiol monoglucuronide (SoMG, 3) and sophoradiol (4) from kaikasaponin III (1). We examined the hepatoprotective effects of these analogs, using immunologically-induced liver injury in primary cultured rat hepatocytes and found that compound 1 was more effective than soyasaponin I (1a) while 2 was more effective than 1. On the other hand, 3 was less effective than 2 at 30-200 μM. Further, compound 3 was strongly cytotoxic at 500 μM while 4 exhibited hepatoprotective activity at the same dose, although less potent. When the cytotoxicity toward hepatocytes of these analogs was tested, only 3 was cytotoxic at doses of 200 and 500 μM. This is the first example of an oleanene glucuronide (OG) which is cytotoxic toward hepatocytes. Compound 3 exhibited hepatoprotective activity at 200 μM, while it was also cytotoxic at the same dose without antiserum. Therefore, the hepatoprotective activity of OG represents a balance between a hepatoprotective action and its cytotoxicity toward hepatocytes.
The inhibitory effects of some flavonoids on the infectivity of rotavirus, which predominantly causes sporadic diarrhea in infants and young children, were investigated. Among tested flavonoids, diosmin and hesperidin had the most potent inhibitory activity on rotavirus infection. The fifty percent inhibitory concentration of both compounds was 10 μM. However, their aglycones did not have the inhibitory activity. The rutinose moiety of flavonoids should protect against the invasion of rotavirus into cells.