Characterization of marmoset CYP2B6: cDNA cloning, protein expression and enzymatic functions.

The common marmoset is a promising species for evaluating the safety of drug candidates. To further understand the capacity for drug metabolism in marmosets, a cDNA encoding a CYP2B enzyme was cloned from the total RNA fraction of marmoset liver by 3'- and 5'-RACE methods. Nucleotide and deduced amino acid sequences showed 90.

Perspectives on non-clinical safety evaluation of drug metabolites through the JSOT workshop.

The prompt and appropriate safety assessment of drug metabolite(s) was mentioned in regulatory guidances such as an International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH) guidance, entitled "Guidance on Non-clinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals" (ICH M3(R2)) implemented in January 1 of 2011 in Japan, and has become a significant issue in the drug development. Upon release of ICH M3(R2) Step 4, a survey was conducted between March and April 2010 on the safety assessment of drug metabolites in 63 member companies of the Japan Pharmaceutical Manufacturers Association (JPMA). The Pharmacokinetics Team in the Non-Clinical Evaluation Expert Committee in JPMA conducted a questionnaire survey and compiled the results to comprehend how safety of drug metabolites are currently assessed at research-based pharmaceutical companies in Japan.

Intrathecal disposition of ARTCEREB® irrigation and perfusion solution for cerebrospinal surgery in rats.

We investigated the disposition of ARTCEREB® irrigation and perfusion solution (Artcereb) during intrathecal perfusion in a lateral ventricle-cisternal perfusion model in conscious rats. In this perfusion model, the perfusion rate was set at 0.35 ml/kg/h, taking into consideration the clinical perfusion rate (500 ml/60 kg/d).

Regio- and stereoselective oxidation of propranolol enantiomers by human CYP2D6, cynomolgus monkey CYP2D17 and marmoset CYP2D19.

Toxic and pharmacokinetic profiles of drug candidates are evaluated in vivo often using monkeys as experimental animals, and the data obtained are extrapolated to humans. Well understanding physiological properties, including drug-metabolizing enzymes, of monkeys should increase the accuracy of the extrapolation. The present study was performed to compare regio- and stereoselectivity in the oxidation of propranolol (PL), a chiral substrate, by cytochrome P450 2D (CYP2D) enzymes among humans, cynomolgus monkeys and marmosets.

Expression levels of drug-metabolizing enzyme, transporter, and nuclear receptor mRNAs in a novel three-dimensional culture system for human hepatocytes using micro-space plates.

We evaluated a novel three-dimensional primary culture system using micro-space plates to determine the expression levels of 61 target (drug-metabolizing enzymes, transporters, and nuclear receptors) mRNAs in human hepatocytes. We measured mRNA expression levels of many target genes in four lots of cryopreserved human hepatocyte primary cells after 120 h of culture and compared differences in mRNA expression levels between cultures using traditional plates and those using micro-space plates. In this study, we show that the mRNA levels of many experimental targets in human hepatocytes before inoculation resemble the levels inside the human liver.

Pharmacological assessment of ARTCEREB irrigation and perfusion solution for cerebrospinal surgery using primary cultures of rat brain cells.

ARTCEREB irrigation and perfusion solution (Artcereb), an ethical pharmaceutical, is typically applied inside the skull and spinal cavity as artificial fluid. Artcereb is composed of glucose and electrolytes (Na+, K+, Mg2+, Ca2+, Cl-, HCO3- and P) and has a pH of 7.3.

Functional characterization of human and cynomolgus monkey UDP-glucuronosyltransferase 1A1 enzymes.

Aims: UDP-glucuronosyltransferase 1A1 (UGT1A1) plays important roles in the glucuronidation of various drugs and endogenous substances. Cynomolgus monkeys are regarded as experimental animals closer to humans in studies on safety evaluation and biotransformation for drug development. In this study, the similarities and differences in the enzymatic properties of UGT1A1 between humans and cynomolgus monkeys were precisely identified.

Secretion of albumin and induction of CYP1A2 and CYP3A4 in novel three-dimensional culture system for human hepatocytes using micro-space plate.

We evaluated a novel primary three-dimensional culture system for human hepatocytes using micro-space plates. The functional activity of human hepatocytes in primary culture was determined by measuring albumin secretion from hepatocytes to medium and measuring expression levels of albumin, CYP1A2 and CYP3A4 mRNA. Albumin secretion was higher in micro-space plates compared with traditional plates after 72 h of culture; the levels of albumin secretion from hepatocytes to medium in culture using micro-space plates after 96 h of culture were 2.

[Pharmacological assessment of ARTCEREB irrigation and perfusion solution for cerebrospinal surgery based on glucose incorporation activity in primary cultures of rat brain cells].

ARTCEREB irrigation and perfusion solution (Artcereb) is typically used as an artificial fluid for applications inside the skull and spinal cavity. This in vitro study was conducted to assess the effects of Artcereb in cultures of rat fetal brain cells. Cell function following exposure to Artcereb was evaluated by measuring (3)H-deoxy-D-glucose incorporation activity.

Approach for in vivo protein binding of 5-n-butyl-pyrazolo[1,5-a]pyrimidine bioactivated in chimeric mice with humanized liver by two-dimensional electrophoresis with accelerator mass spectrometry.

Drug development of a potential analgesic agent 5-n-butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a]pyrimidine was withdrawn because of its limited hepatotoxic effects in humans that could not be predicted from regulatory animal or in vitro studies. In vivo formation of glutathione conjugates and covalent binding of a model compound 5-n-butyl-pyrazolo[1,5-a]pyrimidine were investigated in the present study after intravenous administration to chimeric mice with a human or rat liver because of an interesting capability of human cytochrome P450 1A2 in forming a covalently bound metabolite in vitro. Rapid distribution and elimination of radiolabeled 5-n-butyl-pyrazolo[1,5-a]pyrimidine in plasma or liver fractions were seen in chimeric mice after intravenous administration.

Evaluation of induction potency of new drug candidates on CYP1A2 and CYP3A4 using real-time one-step RT-PCR in primary cultures of cryopreserved human hepatocytes.

This study evaluates the induction potency of new drug candidates on mRNA levels of CYP1A2 and CYP3A4 in primary cultures of cryopreserved human hepatocytes. Analysis was performed by quantitative real-time RT-PCR using primers and TaqMan probes. Positive controls for CYP1A2 and CYP3A4 used beta-naphthoflavone (beta-NF) and rifampicin (Rif), respectively.

Perfusion fluids used in neurosurgery affect cerebrospinal fluid and surrounding brain parenchyma in the rat ventriculocisternal perfusion model.

ARTCEREB, an irrigation and perfusion solution (Artcereb), is a preparation intended for the irrigation and perfusion of the cerebral ventricles, and it is therefore important to evaluate its effects on cerebrospinal fluid (CSF) and on the surrounding cerebrospinal parenchyma. To confirm the kinetics of the perfusion fluid component, we performed whole body autoradiography and examined glucose balance during ventriculocisternal perfusion with (14)C-glucose labeled Artcereb in the rat model, which simulates ventricular irrigation or ventriculocisternal perfusion in clinical neurosurgery. We also performed ventriculocisternal perfusion with Artcereb, lactated Ringer's solution, or normal saline, and observed the effect of these solutions on animal condition and on brain tissue morphology.

Depletion of selenoprotein GPx4 in spermatocytes causes male infertility in mice.

Phospholipid hydroperoxide glutathione peroxidase (GPx4) is an intracellular antioxidant enzyme that directly reduces peroxidized phospholipids. GPx4 is strongly expressed in the mitochondria of testis and spermatozoa. We previously found a significant decrease in the expression of GPx4 in spermatozoa from 30% of infertile human males diagnosed with oligoasthenozoospermia (Imai, H.

[ARTCEREB irrigation and perfusion solution for cerebrospinal surgery: pharmacological assessment using human astrocytes exposed to test solutions].

ARTCEREB irrigation and perfusion solution (Artcereb) is a preparation intended for the irrigation and perfusion of the cerebral ventricles, and it is therefore important to evaluate the effects of Artcereb on brain cells. In vitro assessment of the effects of Artcereb in cell cultures of human fetal astrocytes was conducted in comparison with normal saline and lactated Ringer's solution. The effects of exposure to Artcereb were evaluated based on microscopic images of the mitochondria stained with rhodamine 123.

Tissue-specific mRNA expression profiles of drug-metabolizing enzymes and transporters in the cynomolgus monkey.

Pairs of forward and reverse primers and TaqMan probes specific to each of 19 drug-metabolizing enzymes (cytochrome P450s, UDP-glucuronosyltransferases, glutathione S-transferases, and sulfotransferases) and 5 transporters (ABC and SLC transporters) in the cynomolgus monkey were prepared. The expression level of each target mRNA was analyzed in total RNA obtained from three specimens of various cynomolgus monkey tissues (adrenal gland, brain, heart, kidney, large intestine, liver, lung, pancreas, prostate, small intestine, spleen, testis, and thymus) by real-time reverse transcription PCR using an Applied Biosystems 7500 Fast Real-Time PCR System. The data obtained in the present study provide useful information on tissue-specific profiles of the expression of these target mRNAs in the cynomolgus monkey, and the results are expected to be valuable in establishing drug metabolism- and transporter-mediated screening systems using the cynomolgus monkey for the evaluation of new chemical entities in new drug development.

Tissue-specific mRNA expression profiles of human solute carrier 35 transporters.

Pairs of forward and reverse primers and TaqMan probes specific to each of 23 human solute carrier 35 (SLC35) transporters were prepared. The mRNA expression level of each target transporter was analyzed in total RNA from single and pooled specimens of adult human tissues (adipose tissue, adrenal gland, bladder, bone marrow, brain, cerebellum, colon, heart, kidney, liver, lung, mammary gland, ovary, pancreas, peripheral leukocytes, placenta, prostate, retina, salivary gland, skeletal muscle, small intestine, smooth muscle, spinal cord, spleen, stomach, testis, thymus, thyroid gland, tonsil, trachea, and uterus), from pooled specimens of fetal human tissues (brain, heart, kidney, liver, spleen, and thymus), and from three human cell lines (HeLa cell line ATCC#: CCL-2, human cell line Hep G2, and human breast carcinoma cell line MDA-435) by real-time reverse transcription PCR using an Applied Biosystems 7500 Fast Real-Time PCR System. The mRNA expression of SLC35As, SLC35Bs, SLC35Cs, SLC35D1, SLC35D2, SLC35Es, and SLC35F5 was found to be ubiquitous in both adult and fetal tissues.

Human cytochrome P450 1A2 involvement in the formation of reactive metabolites from a species-specific hepatotoxic pyrazolopyrimidine derivative, 5-n-butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a]pyrimidine.

5-n-Butyl-7-(3,4,5-trimethoxybenzoylamino)pyrazolo[1,5-a]pyrimidine) (OT-7100) is a pyrazolopyrimidine derivative with potential analgesic effects. Exclusively limited elevations in serum levels of aspirate- and alanine-aminotransferase were abnormally observed in a clinical study, in contrast to no toxicological potential to experimental animals. The aim of this study was to clarify the mechanism responsible for species-specific hepatotoxicity of this model compound.

The mechanism causing the difference in kinetic properties between rat CYP2D4 and human CYP2D6 in the oxidation of dextromethorphan and bufuralol.

The capacity to oxidize bufuralol (BF) and dextromethorphan (DEX) was compared kinetically between human CYP2D6 and four rat CYP2D (CYP2D1, -2D2, -2D3 and -2D4) isoenzymes in a yeast cell expression system. In BF 1''-hydroxylation and DEX O-demethylation, only CYP2D4 showed hook-shaped Eadie-Hofstee plots, the other four CYP2D enzymes exhibiting linear plots. In DEX N-demethylation, rat CYP2D2 did not show any detectable activity under the conditions used, whereas the other four enzymes yielded linear Eadie-Hofstee plots.

Comparison of inducibility of multidrug resistance (MDR)1, multidrug resistance-associated protein (MRP)1, and MRP2 mRNAs by prototypical microsomal enzyme inducers in primary cultures of human and cynomolgus monkey hepatocytes.

This study investigated the changes in the mRNA levels of the ATP binding cassette (ABC) transporters multidrug resistance 1 (MDR1), multidrug resistance-associated protein 1 (MRP1), and multidrug resistance-associated protein 2 (MRP2) following exposure to the prototypical microsomal enzyme inducers rifampicin (Rif), dexamethasone (Dex), and omeprazole (Ome) in primary cultures of cryopreserved human and cynomolgus monkey hepatocytes. Analysis was performed by real-time reverse transcription-polymerase chain reaction using primers and TaqMan probes. First, the time course of the mRNA expression of these transporters in primary cultures of human and cynomolgus monkey hepatocytes was examined in detail.

Stereoselective glucuronidation of propranolol in human and cynomolgus monkey liver microsomes: role of human hepatic UDP-glucuronosyltransferase isoforms, UGT1A9, UGT2B4 and UGT2B7.

The stereoselective glucuronidation of propranolol (PL) in human and cynomolgus monkey liver microsomes, and the roles of human hepatic UDP-glucuronosyltransferase (UGT) isoforms involved in the enantiomeric glucuronidation of PL using recombinant UGT enzymes were investigated. In Michaelis-Menten plots, R- and S-PL glucuronidation by human liver microsomes showed sigmoidal kinetics whereas the kinetics of enantiomeric PL glucuronidation by cynomolgus monkey liver microsomes was monophasic. The Km, Vmax and CLint values of cynomolgus monkey liver microsomes were generally higher than the S50, Vmax and CLmax values of human liver microsomes in R- and S-PL glucuronidation.

Comparison of inducibility of sulfotransferase and UDP-glucuronosyltransferase mRNAs by prototypical microsomal enzyme inducers in primary cultures of human and cynomolgus monkey hepatocytes.

We investigated the change of the mRNA levels of sulfotransferase and UDP-glucuronosyltransferase isoforms by the prototypical microsomal enzyme inducers rifampicin (Rif), dexamethasone (Dex), and omeprazole (Ome) in primary cultures of cryopreserved human and cynomolgus monkey hepatocytes. Real-time RT-PCR analysis was performed using primers and TaqMan probes. Rif, Dex, and Ome increased SULT2A1 mRNA level in both human and cynomolgus monkey hepatocytes in dose-dependent manner, but not SULT1A1 mRNA level.

Tissue-specific mRNA expression profiles of human solute carrier transporter superfamilies.

Pairs of forward and reverse primers and TaqMan probes specific to each of 173 human solute carrier (SLC) transporters were prepared. The mRNA expression level of each target transporter was analyzed in total RNA from single and pooled specimens of various human tissues (adrenal gland, bladder, bone marrow, brain, colon, heart, kidney, liver, lung, mammary gland, ovary, pancreas, peripheral leukocytes, placenta, prostate, retina, salivary gland, skeletal muscle, small intestine, smooth muscle, spinal cord, spleen, stomach, testis, thymus, thyroid gland, trachea, and uterus) by real-time reverse transcription PCR using an Applied Biosystems 7500 Fast Real-Time PCR System. Individual differences in the mRNA expression of human SLC transporters in the liver were also evaluated.

The roles of amino acid residues at positions 216 and 219 in the structural stability and metabolic functions of rat cytochrome P450 2D1 and 2D2.

We examined the effects of the mutual substitution of amino acid residues at positions 216 and 219 between rat CYP2D1 and CYP2D2 on their microsomal contents and enzymatic functions using a yeast cell expression system and 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT) as a substrate. CYP2D1 has amino acid residues, leucine and valine, at positions of 216 and 219, respectively, whereas CYP2D2 has phenylalanine and aspartic acid at the same positions. In reduced carbon monoxide-difference spectroscopic analysis, the substitution of Asp-219 of CYP2D2 by valine markedly increased a peak at 450 nm and concomitantly decreased a peak at 420 nm, while the replacement of Phe-216 of CYP2D2 with leucine gave no observable change.

Oxidation of 5-methoxy-N,N-diisopropyltryptamine in rat liver microsomes and recombinant cytochrome P450 enzymes.

The oxidative metabolism of 5-methoxy-N,N-diisopropyltryptamine (5-MeO-DIPT), a tryptamine-type designer drug, was studied using rat liver microsomal fractions and recombinant cytochrome P450 (CYP) enzymes. 5-MeO-DIPT was biotransformed mainly into a side-chain N-deisopropylated metabolite and partially into an aromatic ring O-demethylated metabolite in liver microsomal fractions from untreated rats of both sexes. This metabolic profile is different from our previous findings in human liver microsomal fractions, in which the aromatic ring O-demethylation was the major pathway whereas the side-chain N-deisopropylation was minor [Narimatsu S, Yonemoto R, Saito K, Takaya K, Kumamoto T, Ishikawa T, et al.