When estradiol 17-sulfate (ES) was incubated with human placental microsomes under an NADPH-generating system, 2- and 4-hydroxyestradiol 17-sulfates (2- and 4-OH-ES) formed as the main products. By kinetic experiments, the apparent Km values of 44.0 and 360 μM and apparent Vmax values of 236 and 140 pmol/mg protein/10 min were obtained for the 2- and 4-hydroxylation, respectively. The results indicate that human placental microsomes have fairly high 2- and 4-hydroxylase activities toward ES. This paper describes the formation of 2- and 4-OH-ES and speculates on their physiological role during pregnancy.
A series of four aliphatic carboxylic acid esters (acetate, caproate, laurate and palmitate) of 2-(4-hydroxyphenyl)-4, 5-diphenylimidazole (HDPI) was prepared. Usefulness of these esters as fluorescent substrates for the measurement of lipase activity was evaluated using a high performance liquid chromatographic method. The hydrolysate, HDPI, could be well separated from each substrate by a reversed-phase column and detected at 440 nm emission (cutoff-filter) with 360 nm excitation. Lipase from Candida cylindracea was used for the investigation. From their kinetic parameters, the caproate and laurate were found to be suitable for the lipase. Using the laurate, from 5 to 500 mU per assay tube of the lipase was determined.
Effects of murine serum (NMS) treatment on (1→3)-β-D-glucan inhibitable uptake of zymosan particles (ZYM) (GIZUP) by murine peritoneal macrophages (PM) and the structural specificity of the inhibition were examined. ZYM uptake by PM treated with NMS was enhanced in comparison with those treated with medium, and in a concentration-and incubation time-dependent manner. The enhanced ZYM uptake was significantly reduced by the pretreatment of PM with soluble (1→3)-β-D-glucans. These facts suggest that NMS enhances GIZUP. The effect disappeared by the treatment of NMS with gelatin-Sepharose which removed fibronectin (FN) from the serum, suggesting a significant contribution of FN on GIZUP. In addition, the administration of β-glucan in vivo elevated the concentration of FN in serum by acute phase response and enhanced GIZUP, suggesting the positive contribution of acute phase responses on β-glucan mediated immunopharmacological activities. Of particular interest, the inhibition was shown by both antitumor active and inactive glucans. These facts suggested that the recognition of β-glucans by PM, which would proceed at a relatively early period of whole activation pathways, would not be enough to fully activate the host to show antitumor activity.
SP-40, 40 bound to β-endorphin via C-terminal non-opioid portion of β-endorphin as well as S-protein (vitronectin) bound. Beta-endorphin bound mainly to SP-40, 40, but not to S-protein, in the soluble membrane attack complex (SMAC, SC5b-9) of complement, because the results of autoradiography of the cross-linking experiment of SMAC with [125I]β-endorphin revealed only a typical band of SP-40, 40. The binding of SP-40, 40 to β-endorphin inhibited the binding of β-endorphin to its receptor of rat brain; thus SP-40, 40 might inhibit the biological action of β-endorphin.
3-Fluorinated quinoline (3FQ), a non-mutagenic derivative of the potent mutagen quinoline, was metabolized with a microsomal enzyme fraction isolated from the 3-methylcholanthrene-treated rat liver. The metabolites were 3-fluoro-5, 6-dihydroquinoline-5, 6-trans-diol (72%), 3-fluoroquinoline 1-oxide (6%), 3-fluoro-5, 6-dihydroquinoline-5, 6-cis-epoxide (1%), and 4 unidentified metabolites (11%). Since this metabolic pattern is similar to that obtained with unfluorinated quinoline, the epoxidation of the benzene moieties of quinoline and 3-fluoroquinoline is most likely a detoxication process and not mutagenic activation.
Controlled Smith degradation of ukonan C, a phagocytosis-activating polysaccharide isolated from the rhizome of Curcuma longa L., was performed. The reticuloendothelial system-potentiating, anti-complementary and alkaline phosphatase-inducing activities of ukonan C and its degradation products were investigated. Methylation analyses of the primary and secondary Smith degradation products and of a de-arabinoxylated product indicated that structural features of the arabinogalactan core of ukonan C include a backbone chain composed of β-1, 3-linked D-galactose and β-1, 4-linked D-xylose. All of the galactose units in the backbone carry side chains composed of β-1, 6-linked D-galactosyl residues with or without terminal α-L-arabinose units at position 3.Ukonan C showed remarkable effects on both reticuloendothelial system-potentiating and alkaline phosphatase-inducing activities. Periodate oxidation caused a decrease in or disappearance of the immunological activities, but the controlled Smith degradation product having the arabinogalactan core structure of polysaccharide showed a pronounced effect on anti-complementary activity.
Three rhamnose-binding lectins were purified from the roe of Osmerus eperlanus mordax (olive rainbow smelt) by affinity chromatography and ion-exchange chromatography. The apparent molecular weights of Osmerus eperlanus mordax lectin (OML) -1, -2 and -3 were 25000, 32000 and 26000, respectively, on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) under reducing conditions. On native PAGE, these three lectins showed different migration patterns (Rm value; 0.37, 0.53 and 0.66, respectively). OMLs agglutinated rabbit and human type B erythrocytes and sarcoma 180 cells, but not human type A and O erythrocytes and AH109A cells. The most effective monosaccharide inhibitor was L-rhamnose. L-Mannose and D-galactose were also good inhibitors. Furthermore, OML-induced hemagglutination was inhibited more strongly by melibiose or raffinose rather than lactose or lactulose. Therefore, OMLs are L-rhamnose/α-D-galactosyl type lectins. OMLs did not require a detergent, when extracted from crude material, and Ca2+, Mg2+, EDTA and dithiothreitol were not necessary for the OML-induced hemagglutination activities. The OMLs had similar N-terminal amino acid sequences.
The protective effects of combined treatment with diethyldithiocarbamate (DED) plus N-benzyl-D-glucamine dithiocarbamate (BGD) or DED plus N-p-isopropylbenzyl-D-glucamine dithiocarbamate (PBGD) against the testicular toxicity caused by acute exposure to cadmium (Cd) in rats were studied. Rats were injected subcutaneously with 109CdCl2 (3 mg Cd and 74 kBq of 109Cd/kg) and 30 min later, they were injected intraperitoneally with the chelating agents (1 mmol/kg each). Cd injection increased lipid peroxidation and concentrations of hemoglobin, Ca and Fe in the testes, decreased the testicular weight and nonprotein SH (NP-SH), and caused sterility. The coadministration of DED with BGD or PBGD significantly prevented the increase in the lipid peroxidation, hemoglobin, Ca and Fe in the testes, the decrease in the testicular weight and NP-SH, and the sterility caused by Cd injection. DED plus BGD or DED plus PBGD significantly decreased the Cd concentration in the testes without the redistribution of Cd to the brain and kidney, which is observed following treatment with DED alone. The coadministration of DED plus BGD or DED plus PBGD significantly increased the blood Cd concentration and the Cd distribution in the red blood cells compared to Cd alone. These results indicate that the coadministration of BGD or PBGD with DED prevents the accumulation of Cd in the testes on the basis of greater blood distribution of Cd, which results from the uptake of Cd by the red blood cells, without the redistribution of Cd to the brain, resulting in an improvement of the protective effect of DED against the Cd-induced testicular toxicity.
From the study using cultured human and mouse neuroblastoma cells, we found that a new type of synthetic bicyclic pyrimidine compounds possessing piperazine moiety strongly promoted neurite outgrowth in neuroblastoma cell lines human GOTO and mouse neuro 2a. The most effective compounds of these 2-piperazinopyrimidine derivatives possessing nerve growth factor (NGF)-like activity were 2-piperazino-6-oxo-5, 6-dihydro(7H)pyrrolo[2, 3-d]pyrimidine and 2-piperadino-6-methyl-5-oxo-5, 6-dihydro(7H)pyrrolo[3, 4-d]pyrimidine. The piperazinopyrimidine compounds were also shown to potentiate NGF-induced neurite sprouting of rat pheochromocytoma PC12 cells. The compounds were more effective in cell cultures than isopropylaminopyrimidine (isaxonine) which had been previously developed and then withdrawn. We discussed the merit of the method of the screening of neurotropic compounds by neurite sprouting activity in cultured neuroblastoma cells.
Effect of the simultaneous use of l-menthol and ethanol on the skin permeation of six potent cardiovascular agents : nicardipine hydrochloride, atenolol, captopril, nifedipine, vinpocetine and nilvadipine (in hydrophilic order) was investigated to evaluate the feasibility of their use in a transdermal therapeutic system (TTS). In vitro diffusion experiments were carried out using excised hairless rat and human skin, and the application area of TTS required for the minimum therapeutic effect was estimated by a simple pharmacokinetic calculation. Marked enhancing effect by the l-menthol-ethanol system was found independent of drug lipophilicity, but the mode action was dependent on the lipophilicity of the drug. The action of the system on lipophilic drugs (nifedipine, vinpocetine and nilvadipine) was mainly due to their increase in solubility in the system, while that on hydrophilic (or water soluble) drugs (nicardipine hydrochloride, atenolol and captopril) was the result of increase in their skin permeability coefficient. This enhancing effect was adequate to assure their minimum effective concentration (MEC) in human. The area of application of a drug to maintain the MEC was calculated to be 0.15 cm2 for hydrophilic or water soluble drugs and 3.7-13 cm2 for lipophilic drugs.
The effects of various absorption promoters on the pulmonary absorption of drugs with different molecular weights were examined in rats. Phenol red and fluorescein isothiocyanate-labeled dextrans (FDs) with various molecular weights were used as model drugs and the absorption promoters used in this study were sodium glycocholate, sodium salicylate, ethylenediaminetetraacetic acid disodium salt (Na2-EDTA) and sodium caprate, all at a concentration of 1%. Of these absorption promoters, sodium glycocholate and sodium caprate appeared to be more effective for enhancing the pulmonary absorption of these drugs than sodium salicylate and Na2-EDTA. Furthermore, it was indicated that there is the optimal molecular weight to which each absorption promoter gives the largest enhancing effect on the pulmonary absorption of drugs.
The in vitro release of bumetanide from macrogol suppositories with and without weak acids (citric acid and tartaric acid) was studied. The release of bumetanide was not affected when weak acids added to the suppositories. The in vivo rectal absorption of bumetanide from the suppositories was evaluated in rabbits. The bioavailability (absolute), expressed as the ratio of the area under the plasma concentration-time curve (AUC) following oral administration of bumetanide, was 39% that of intravenous administration. The value in humetanide following rectal administration of the suppositories without weak acids was 32%. Each absolute bioavailability following rectal administration of the suppositories with 5% citric acid and 5% tartaric acid was 52% and 42%, respectively. These values were significantly larger than those of rectal administration of the suppositories without weak acids. Particularly, the bioavailability following rectal administration of the suppositories containing citric acid was significantly different from even those of oral administration. The absorption rate constants of bumetanide from the suppositories with weak acids were significantly larger than those following oral administration. These results indicated the possibilities of the rectal route of administration of drugs which are weak organic acids and show low or variable bioavailability following oral administration.
The in vivo release of four water-soluble drugs, cefadroxil, cephradine, antipyrine and 4-aminoantipyrine, from a stabilizing water-in-oil-in-water (W/O/W) type multiple emulsion was studied using rats. The W/O/W type multiple emulsion used in this study could be stabilized for 30 d after preparation at room temperature and also for 24 h in pH 7.4 isotonic phosphate buffer or in rat plasma at 37°C. The cefadroxil and cephradine concentrations in rat plasma following intravenous administrations of their W/O/W type multiple emulsions containing drugs were considerably prolonged compared with those of respective aqueous solutions. Sustained-releasing properties of cefadroxil and cephradine from W/O/W type multiple emulsions could be explained by the mechanism underlying the long residence time of W/O/W type multiple emulsions and delay-release of drugs from the W/O/W type multiple emulsions circulated with rat blood stream. However, antipyrine and 4-aminoantipyrine decreased rapidly following W/O/W type multiple emulsions and these plasma profiles coincided precisely with those following intravenous administration of the aqueous solutions of drugs. These in vivo releasing data correlated with in vitro drug release observation stated in the previous papers [W. Zhang et al., Yakugaku Zasshi, 112, 73 (1992); S. Goto et al., ibid., 111, 702 (1991)].
A physiologically based pharmacokinetic model was established to describe the hepatobiliary excretion process for ligands which are excreted into the bile without metabolic conversion. In this model, the following processes were taken into consideration : influx and efflux across the liver sinusoidal membrane, intracellular diffusion, and excretion across the canalicular membrane into the bile. The partial differential equation by which these processes were described was solved to obtain the Laplace transformed solution for the biliary excretion rate of ligands, based on the plasma concentration profiles as an input function. The time profiles for the biliary excretion rate of dibromosulfophthalein (DBSP; 6.80 mg/kg b.w.) or cefodizime (15.0 mg/kg b.w.) after i.v. bolus administration to rats were fitted to the solution using a nonlinear least-squares program based on a fast inverse Laplace transform (MULTI-FILT [Y. Yano et al., Chem. Pharm. Bull., 37, 1035 (1989)]) to determine the permeability-surface area product across the plasma membrane as well as the apparent intracellular diffusion coefficient. DBSP and cefodizime were used as model compounds since these two ligands possess different binding characteristics for cytosol protein(s). Although both ligands are present predominantly in the cytosol, DBSP binds to intracellular protein(s) (such as ligandin) to a great extent whereas the protein binding of cefodizime is not so extensive. The fitted lines were superimposed on the experimental results. The calculated intracellular diffusion coefficient (Dapp) for DBSP (approx. 3.4×10-6cm2/min) was much lower than that for cefodizime (approx. 2.1×10-5cm2/min). These Dapp values were quantitatively accounted for by considering the extent of cytosolic binding of these ligands described previously, based on the assumption that the intracellular diffusion coefficient for bound ligands to the cytosolic protein(s) equals that for the protein(s) (approx. 9.5×10-6cm2/min). Although we could not determine the absolute values for the transport clearance across the membranes based on this model, kinetic analysis indicated that, in some instances, intracellular diffusion can be a rate determining process for the hepatobiliary excretion of ligands. Simulation studies also suggest that alterations in intracellular binding affect the biliary excretion rate of ligands.
A sensitive analytical method for the determination of ambenonium, a selective acetylcholinesterase inhibitor, in plasma was developed. The procedure involves ultrafiltration to remove endogenous plasma cholinesterase, followed by colorimetric measurement of the inhibitory activity to acetylcholinesterase by the thiocholine method. Coefficient of variation of within-day triplicate analysis is less than 20% at the concentration of 5 nM. Detection limit of this method is 1 nM, which is twice lower than the most sensitive HPLC method reported previously. This assay procedure is applied to the pharmacokinetic study of ambenonium after intravenous administration of low dose (10-20 nmol/kg) to rat. This new method is rapid and simple and makes it possible to determine the ambenonium concentration in plasma with good accuracy.
Model lipid mixtures composed of ceramide (40%), cholesterol (25%), palmitic acid (25%) and cholesterol 3-sulfate (10%) were used as the model for intercellular lipids of stratum corneum (SC) to evaluate a barrier function of SC for drug permeation. Six β-blockers, propranolol, metoprolol, timolol, pindolol, nadolol and atenolol, were used as the model permeants. The maximum flux values (observed flux/thermodynamic activity, Jmax) of drugs through the membrane coated with the model lipid mixtures and two keratinized membranes, rat skin and hamster cheek pouch, were determined in vitro using a Franz-type diffusion cell. Further, drug partition coefficients to the multilamellar liposomes prepared by the model lipid mixtures were determined. The Jmax values obtained in the model lipid-coated membrane, in the intact rat skin and in the intact hamster cheek pouch mucosa, bore a linear relationship to each other. These results suggest that the model lipid-coated membrane is a useful tool for the prediction of the drug permeability through the keratinized membrane in the in vitro system. The Jmax values also correlated with drug partition to the model lipid liposomes, suggesting the validity of the use of the model lipid mixtures as the substitutes for the intercellular lipids of the stratum corneum.
Recent studies by our group suggested that lysozyme (LZM) has a high affinity for bacterial lipopolysaccharide (LPS) of both the smooth and rough forms, and inhibits various immunomodulatory activities of LPS. GLA60 is a synthetic monosaccharide analogue of bacterial lipid A, well-know as sharing large part of lipid A activities but with very low toxicity. In this study, we characterized the interaction of LZM with GLA60 in comparison to that with E. coli 0111 LPS (smooth form), taking a physicochemical approach. Using a dansylated lysozyme probe (DNS-LZM), LZM was found to bind to GLA60 in all 3 of its forms, free acid, triethylamine (TEA) salt and bovine serum albumin (BSA) complex of GLA60, as well as natural LPS. Compared with LPS, the complex formation of the TEA salt was weakly dependent on temperature and incubation time. LZM also bound to biologically inactive GLA analogues, GLA64 and GLA69, at a high affinity, as well as to GLA 60. By using chemically modified LZM, it was found that the ionic as well as hydrophobic interactions are important for the complex formation.
The mechanism of uptake of glycyrrhizin (GLZ) by isolated rat liver cells was studied. The uptake rate was dependent on the unbound GLZ concentation. The initial uptake rate with respect to the unbound GLZ concentration reflected the operation of both saturable and nonsaturable processes, which followed Michaelis-Menten type kinetics; the process involves a Km of 11.3 μM, Vmax of 0.112 nmol/min/106 cells, and a first-order rate constant (Kd) of 0.195 nmol/min/106 cells/mM. GLZ adsorption on the cell membrane occurs at two types of binding sites with a linear adsorption coefficient=2.81 nmol/106 cells/mM and a dissociation constant=18.3 μM and its adsorption capacity=0.12 nmol/106 cells describing specific adsorption. GLZ uptake did not require the presence of Na+ in the incubation medium and was not significantly inhibited by ouabain. The Arrhenium plot of uptake of 10 μM GLZ presented a single straight line in the range of 4-37°C, with an activation energy of 15.9 kcal/mol. An energy requirement was also demonsrated, as all metabolic inhibitors studied (rotenone, antimycin A, 2, 4-dinitrophenol, and KCN) significantly reduced the uptake of 10 μM GLZ (p<0.01). The uptake was competitively inhibited by glycyrrhetinic acid (GLA), taurocholate (TCA), and probenecid (PBC) with inhibition constants, Ki, of 13.7, 48.5, and 115.9 μM, respectively, and it was noncompetitively inhibited by bromosulfophthalein (Ki 9.2 μM) and indocyanine green (Ki 13.5 μM) only at low GLZ concentrations (5 and 10 μM).It was concluded that a carrier-mediated transport system participates in the uptake of GLZ into isolated rat hepatocytes and the affinity site of the transport carrier commonly binds GLA, TCA, and PBC.
The stereoselective disposition of pranoprofen, a nonsteroidal antiinflammatory drug, was studied in rabbits. Plasma levels of S(+)-pranoprofen after oral and i.v. administration of the racemate pranoprofen were always higher than those of the R(-)-isomer. The elimination rate constant of the R(-)-isomer (2.74 h-1), calculated using a 2-compartment model, was significantly larger than that of the S(+)-isomer (2.14 h-1), while no significant difference was observed in the absorption rate constants between enantiomers. Pranoprofen was excreted in the urine exclusively in the form of pranoprofen glucuronide. The glucuronide of R(-)-isomer was excreted more rapidly than the S(+)-isomer. However, no metabolite of pranoprofen was detected in plasma, owing to its instability in liver and plasma. Moreover, the elimination of the S(+)- and R(-)-isomers of pranoprofen was more rapid when the enantiomers were separately administered than when administered as the racemate. The R(-)-isomer showed a significantly higher elimination rate than the S(+)-isomer, compared to what was observed upon the administration of the racemate. No inversion to an R(-)-form or S(+)-form to their corresponding antipode after administration of the isomers separately was detected. Pranoprofen, especially the R(-)-isomer, was significantly distributed in the kidney. An in vitro metabolism experiment of pranoprofen showed the predominant glucuronidation to be in the kidney rather than in the liver because of rapid hydrolysis of glucuronide in the liver. The glucuronidation of R(-)-isomer was 4-fold faster than S(+)-isomer in the kidney, although the hydrolysis from glucuronide to pranoprofen in the kidney was faster for R(-)-isomer than S(+)-isomer. It was concluded from the present limited data that conjugation of the R(-)-isomer depended predominantly upon its higher free plasma level and higher metabolic rate and it thus was rapidly excreted from the kidney. This describes the stereoselectivity in the elimination process of pranoprofen which might be responsible for a significant difference in plasma concentration between S(+)- and R(-)-pranoprofen.
A fluorometric method for the assay of rat brain N-methyltransferase (NMT) has been developed using rat brain 9000×g supernatant fluid as an enzyme preparation. The method is based on the enzyme reaction at pH 8.6 using 4-methylnicotinamide (4-MN) as the methyl acceptor substrate in the presence of cofactor S-adenosyl-L-methionine (AdoMet), and the fluorometric determination of the product 1, 4-dimethylnicotinamide by means of its reaction with 4-methoxybenzaldehyde. The apparent Km values for 4-MN and AdoMet were 0.47 mM and 19 μM, respectively. The method was successfully applied to the studies of age- and sex-related differences of brain NMT activity in rats. The enzyme activity decreased gradually between 3 and 14 weeks of age whereas there were no differences between males and females in the levels of NMT activity.
Chondroitin sulfate/dermatan sulfate (CS/DS) hybrid polymers obtained from rat peritoneal resident macrophages were analyzed by the enzymatic method; CS/DS chains were digested by chondroitinase, and the resultant unsaturated disaccharides were determined by HPLC with fluorometric detection. CS/DS in the resident macrophages are constituted of Di-4S, Di-6S, Di-diSE, Di-diSB and Di-triS.
The anti-inflammatory activity of completely reduced and carboxamide-methylated heavy chain of all disulfide bonds in human serum immunoglobulin G (IgG) (C.Fr.I-H) was investigated using some experimental inflammatory models. C.Fr.I-H significantly inhibited carrageenin-induced paw edema and pleurisy, and serotonin-induced paw edema. The carboxamide-methylated heavy chain of interchain disulfide bonds in IgG (Fr.I-H) exhibited similar inhibitory activities to C.Fr.I-H on carrageenin-induced paw edema and pleurisy, while it was ineffective on serotonin-induced paw edema. These results suggest that complete alkylation of disulfide bonds in a heavy chain caused stronger anti-inflammatory activities than partial alkylation.
The promoting effect of d-limonene and l-menthol on the percutaneous absorption of nonionized and ionized diclofenac (DF) was investigated employing a pretreatment method. After the pretreatment of hairless rat skin with an ethanol buffer solution containing terpenes, the permeation study was performed in vitro. The permeability coefficients of nonionized (Pn) and ionized diclofenac (Pi) were calculated under the assumption that the total flux was composed of individual fluxes of nonionized and ionized DF. In the case of pretreatment with d-limonene, both Pn and Pi values were increased dramatically. However, the promoting magnitude was not affected by an extension of the pretreatment period. In contrast, when the skin was pretreated with l-menthol, the Pn and Pi values increased gradually as the pretreatment period increased. Based on the measurement of the solubility of terpenes in the pretreatment solution, the difference in promotiong efficiency could arise from the difference in thermodynamic activity of the terpenes.
The rectal absorption of acyclovir has been evaluated after administration of suppositories without absorption enhancers in rats. The disappearance of plasma acyclovir followed biexponential kinetics after i.v. dosing. Rectal administration of a triglyceride (Vosco S-55 and Vosco S-55+methylcellulose) suppository gave relatively high plasma concentrations and bioavailabilities (95.3 and 83.4%, respectively) compared with Witepsol and macrogol suppositories. However, the in vitro release profiles from suppositories did not accurately reflect plasma concentrations after rectal dosing. Our results suggest that the rectal administration of acyclovir suppositories may be a promising substitute for intravenous infusion, which is at present used for the treatment.
Bioavailability of phytonadione was investigated after oral administration to beagle dogs. The administrations of phytonadione in a surfactant solution (preparation a) and in an oleic acid solution (preparations b) greatly increased the bioavailability of phytonadione. The AUCs of preparations a and b were about 2.5 times larger than those of commercially available tablets A and C. This result well corresponded to the results of the dissolution test previously reported. The absorption of phytonadione from the gastro-intestinal tract was affected by food and the bioavailability was largely increased under non-fasted conditions. However, a large scatter was observed in the data, and it was found that the evaluation of the bioavailability of phytonadione preparations could not be done in non-fasted animals.
In order to understand the fundamental structural features which yield both high serum albumin binding potency and desired property as a prodrug, the derivatization was performed at N-1 or N-3 position in 5-fluorouracil. The N-3 derivatives were more stable than N-1 derivatives in vitro, whereas they were metabolized quickly in vivo. It is suggested that N-1 position should be blocked to avoid fast metabolism in vivo.
A screening method for anti-osteoporotics using ovariectomized rats was designed using a compact method to monitor the bone density. It was found that ovariectomy (OVX) of Wister female rats (11 weeks old) induced acute and focal osteopenia within 2 weeks, which responded well to intermittent salmon calcitonin (SCT : 5 and 20 U/kg, s.c., every other day) employed as the standard anti-osteoporotic and injected up to 4 weeks with or without a delay of 2 weeks after OVX.
Staphylococcus aureus S704 and 8325MMT7 show constitutive resistance to macrolide antibiotics such as erythromycin (EM), oleandomycin, spiramycin, rosamicin and josamycin, except for tylosin, rokitamycin (RKM), and mycinamicin as well as lincosamide and streptogramin type B antibiotics (PM-resistance). Whenever 70S ribosomes from either of them were dissociated into 30S and 50S subunits in a 10-28%(W/W) linear sucrose gradient, the latter subunit was further cleaved into two small apparently equal particles (about 40S). RKM could no longer bind to either of the small particles. A prior exposure of 8325MMT7's 50S subunit to RKM (except EM) did not cause cleavage in any small particles. The largest component (M.W. 33.0kDa) of 50S ribosomal proteins was absent in at least the small particles. The first finding suggests that the lability of the 50S ribosome may be responsible for PM-resistance.
In order to elucidate the drug interaction between diltiazem and diazepam, the effect of diltiazem on the N-demethylation of diazepam in the mouse hepatic microsomes was investigated. Kinetic study showed that diltiazem noncompetitively inhibited the N-demethylation of diazepam with inhibition constant(Ki) value of 247.8 μM, indicating that diltiazem exhibits an inhibitory effect on the hepatic oxidative metabolism of diazepam. It was therefore suggested that diltiazem may impair the metabolism of diazepam in vivo.