Roles of breast cancer resistance protein and organic anion transporting polypeptide 2B1 in gastrointestinal toxicity induced by SN-38 under inflammatory conditions

Drug transporters are among the factors that determine the pharmacokinetic profiles after drug administration. In this study, we investigated the roles of drug transporters involved in transport of SN-38, which is an active metabolite of irinotecan, in the intestine under inflammatory conditions in vitro and determined their functional consequences. The expression alterations of breast cancer resistance protein (BCRP) and organic anion transporting polypeptide (OATP) 2B1 were determined at the mRNA and protein levels, and the subsequent functional alterations were evaluated via an accumulation study with the representative transporter substrates [prazosin and dibromofluorescein (DBF)] and SN-38. We also determined the cytotoxicity of SN-38 under inflammatory conditions. Decreased BCRP expression and increased OATP2B1 expression were observed under inflammatory conditions in vitro, which led to altered accumulation profiles of prazosin, DBF, and SN-38, and the subsequent cytotoxic profiles of SN-38. Treatment with rifampin or novobiocin supported the significant roles of BCRP and OATP2B1 in the transport and cytotoxic profile of SN-38. Collectively, these results suggest that BCRP and OATP2B1 are involved in the increased cytotoxicity of SN-38 under inflammatory conditions in vitro. Further comprehensive research is warranted to completely understand SN-38-induced gastrointestinal cytotoxicity and aid in the successful treatment of cancer with irinotecan.

Pharmacokinetic interactions of niclosamide in rats: Involvement of organic anion transporters 1 and 3 and organic cation transporter 2

Niclosamide is an anthelmintic drug with a long history of use and is generally safe and well tolerated in humans. As the conventional dose of niclosamide results in a low but certain level in systemic circulation, drug interactions with concomitant drugs should be considered. We aimed to investigate the interaction between niclosamide and drug transporters, as such information is currently limited. Niclosamide inhibited the transport activity of OATP1B1, OATP1B3, OAT1, OAT3, and OCT2 in vitro. Among them, the inhibitory effects on OAT1, OAT3, and OCT2 were strong, with IC50 values of less than 1 μM. When 3 mg/kg of niclosamide was co-administered to rats, systemic exposure to furosemide (a substrate of OAT1/3) and metformin (a substrate of OCT2) increased, and the renal clearance (CLr) of the drugs significantly decreased. These results suggest that niclosamide inhibits renal transporters, OAT1/3 and OCT2, not only in vitro but also in vivo, resulting in increased systemic exposure to the substrates of the transporters by strongly blocking the urinary elimination pathway in rats. The findings of this study will support a meticulous understanding of the transporter-mediated drug interactions of niclosamide and consequently aid in effective and safe use of niclosamide.

Proline-Hinged α-Helical Peptides Sensitize Gram-Positive Antibiotics, Expanding Their Physicochemical Properties to Be Used as Gram-Negative Antibiotics

The outer membrane (OM) of Gram-negative bacteria is the most difficult obstacle for small-molecule antibiotics to reach their targets in the cytosol. The molecular features of Gram-negative antibiotics required for passing through the OM are that they should be positively charged rather than neutral, flat rather than globular, less flexible, or more increased amphiphilic moment. Because of these specific molecular characteristics, developing Gram-negative antibiotics is difficult. We focused on sensitizer peptides to facilitate the passage of hydrophobic Gram-positive antibiotics through the OM. We explored ways of improving the sensitizing ability of proline-hinged α-helical peptides by adjusting their length, hydrophobicity, and N-terminal groups. A novel peptide, 1403, improves the potentiation of rifampicin in vitro and in vivo and potentiates most Gram-positive antibiotics. The "sensitizer" approach is more plausible than those that rely on conventional drug discovery methods concerning drug development costs and the development of drug resistance.

A Preliminary Study of Pharmacokinetics and Pharmacodynamics of Oral Fingolimod in Dogs

BACKGROUND/AIM

Fingolimod is a sphingosine-1-phosphate receptor modulator that prevents lymphocytes egress from lymphoid organs. It has been used as a disease-modifying drug for human multiple sclerosis and has shown better therapeutic effects than other conventional therapies. Therefore, this study was performed to obtain preclinical data of fingolimod in dogs.

MATERIALS AND METHODS

Nine laboratory Beagle dogs were used and randomized into three groups for pharmacokinetics (PK) and pharmacodynamics (PD). The dogs were administered once with a low-dose (0.01 mg/kg, n=3), medium-dose (0.05 mg/kg, n=3), and high-dose (0.1 mg/kg, n=3) of fingolimod, orally. Samples were collected serially at predetermined time points, and whole blood fingolimod concentrations were measured using high-performance liquid chromatography-mass spectrometry. Differential counts of leukocytes over time were determined to identify immune cells' response to fingolimod.

RESULTS

Regarding PK, the concentration of fingolimod in the blood increased in a dose-dependent manner, but it was not proportional. Regarding PD, the number of lymphocytes significantly decreased compared to baseline in all dose groups (low-dose, p=0.0002; medium-dose, p<0.0001; high-dose, p=0.0012). Eosinophils were significantly reduced in low- (p=0.0006) and medium- (p=0.0006) doses, and neutrophils were also significantly reduced in medium-(p=0.0345) and high- (p=0.0016) doses.

CONCLUSION

This study provides the basis for future clinical applications of fingolimod in dogs with immune-mediated diseases, such as meningoencephalitis of unknown etiology.

Strong inhibition of organic cation transporter 2 by flavonoids and attenuation effects on cisplatin-induced cytotoxicity

Organic cation transporter 2 (OCT2) is predominantly expressed in the basolateral membrane of renal proximal tubule cells and contributes to the renal excretion of various drugs such as metformin, cisplatin, oxaliplatin, cimetidine, and lamivudine. Cisplatin, an anticancer agent for various cancers, is a substrate of OCT2, and cisplatin-induced nephrotoxicity is in part attributed to OCT2 activity in the kidney, which increases the renal accumulation of cisplatin. In this study, we aimed to identify flavone derivatives with strong inhibitory effects on OCT2 transport. Among the 80 flavonoids tested, 24 showed moderate to strong inhibitory effects against OCT2 transport activity. The IC₅₀ values were less than 5 μM for 10 flavonoids. All 10 compounds alleviated cisplatin-induced cytotoxicity in cells expressing OCT2, even though the magnitude of the effects varied depending on the functional moieties in each position. Multiple factor analysis revealed that the methyl group at the R₁ position and methoxy group at the R₆ position of the flavonol backbone are important for OCT2 inhibition. Information on the functional moieties in the flavonol backbone would help develop effective OCT2 inhibitors by providing a structural association with OCT2 inhibitory effects. In addition, the compounds with strong inhibitory effects on OCT2 identified in this study may be potential candidates for clinical use to mitigate cisplatin-induced nephrotoxicity.

Findings on In Vitro Transporter-Mediated Drug Interactions and Their Follow-Up Actions for Labeling: Analysis of Drugs Approved by US FDA between 2017 and 2021

Understanding possible follow-up actions on in vitro findings helps determine the necessity of labeling for drug interactions. We analyzed information for in vitro findings on transporter-mediated interactions of drugs approved by the U.S. Food and Drug Administration’s Center for Drug Evaluation and Research for the last five years (i.e., 2017–2021) and their follow-up actions for labeling. Higher R values than the pre-defined cut-off were observed with 3.7–39.1% inhibitor drugs in a simple prediction. Among these drugs, 16–41.7% were labeled with their potential drug interactions, while results of supporting studies or scientific rationales were submitted for the other drugs leading to no interaction labeling. In vitro transporter substrates were reported with 1.7–67.6% of drugs. The interaction labels for these substrate drugs were observed in up to 40% of drugs, while the other drugs were not labeled on the drug interactions with claims for their low interaction potential, evidenced by clinical studies or scientific rationales. The systematic and comprehensive analysis in this study will provide insight into the management of in vitro findings for transporter substrate or inhibitor drugs.

Bioanalysis of alpelisib using liquid chromatography–tandem mass spectrometry and application to pharmacokinetic study

Alpelisib is the first alpha-specific phosphatidylinositol-3-kinase (PI3K) inhibitor indicated for the treatment of hormone receptor-positive, human epidermal growth factor receptor 2-negative, PI3K catalytic subunit alpha-mutated, advanced, or metastatic breast cancer. Substantial attempts have been made to extend its clinical use to other types of cancer. Analytical methods proven to accurately quantify alpelisib would improve the reliability of the preclinical and clinical data of alpelisib. Therefore, we developed and validated a quantification method based on liquid chromatography–tandem mass spectrometry for alpelisib in mouse and human plasma samples. Alpelisib and an internal standard (IS; enzalutamide) were separated from endogenous substances using an XTerra MS C18 column with a linear gradient of 0.1% formic acid in water and 0.1% formic acid in acetonitrile. Multiple reaction monitoring transitions for alpelisib and the IS were m/z 442.1 > 328.0 and m/z 465.0 > 209.1, respectively. The calibration curve for alpelisib was confirmed to be linear in the range of 1–2000 ng/mL in both mouse and human plasma. The intra- and inter-day accuracy and precision met the acceptance criteria, and no significant matrix effects were observed. Alpelisib was stable under various storage and handling conditions, and the carryover effect was overcome using the injection loop flushing method. We successfully used this assay to study the in vitro metabolic profiles and in vivo pharmacokinetics of alpelisib in mice. Here, to the best of our knowledge, we report for the first time a valid quantitative method for alpelisib in mouse and human plasma, which could aid in providing valuable pharmacokinetic information on alpelisib to increase its clinical availability.

Pharmacokinetics of fluconazole after oral administration to healthy beagle dogs

BACKGROUND

Fluconazole can be effective in the treatment of superficial mycoses in dogs. However, the pharmacokinetics of fluconazole have not yet been evaluated to determine its optimal dosing regimen.

OBJECTIVES

This study aimed to determine the plasma concentration of fluconazole after single and multiple administrations at two different dosages in dogs.

METHODS AND MATERIALS

Eight healthy beagle dogs were divided into two groups, and each group received either 5 or 10 mg/kg of fluconazole per os. The pharmacokinetics of fluconazole was determined following single and multiple administrations p.o. Single- and multiple-dose treatment periods were separated by a washout period of seven days. Plasma concentrations of fluconazole were determined by established high-performance liquid chromatography coupled with tandem mass spectrometry system.

RESULTS

In the 5 mg/kg group, the mean maximum concentrations (C_max ) and the area under the plasma concentrations (AUC_0-24h ) were 4.84 μg/mL and 85.56 μg*h/mL, respectively, after single administration and 6.58 μg/mL and 119.52 μg*h/mL, respectively, after multiple administrations. In the 10 mg/kg group, the C_max and AUC_0-24h were 5.67 μg/mL and 109.19 μg*h/mL, respectively, after single administration and 15.10 μg/mL and 291.51 μg*h/mL, respectively, after multiple administrations. The C_max (p < 0.001) and AUC_0-24h (p < 0.001) were significantly lower in the 5 mg/kg group than those in the 10 mg/kg group at multiple administrations.

CONCLUSIONS AND CLINICAL RELEVANCE

Fluconazole accumulates in plasma and exhibits dose-proportional pharmacokinetics after multiple doses, and was safe and well tolerated at these doses for short-term administration.

Sensitive and valid assay for reliable evaluation of drug interactions mediated by human organic anion transporter 1 and 3 using 5-carboxyfluorescein

Drug interactions can induce significant clinical impacts, either by increasing adverse effects or by decreasing the therapeutic effect of drugs, and thus, need to be explored thoroughly. Clinically significant drug interactions can be induced by organic anion transporter 1 (OAT1) and OAT3 when concomitant medications competitively interact with the transporters. The purposes of this study were to develop and validate a sensitive and selective analytical method for 5-carboxyfluorescein (5-CF) and optimize the experimental conditions for interaction studies. An analytical method using high-performance liquid chromatography (HPLC) equipped with a fluorescence detector was validated for accuracy, precision, matrix effect, recovery, stability, dilutional integrity, and carry-over effect. In addition, the 5-CF concentration, incubation period, and washing conditions for interaction study were optimized. Using a valid analytical method and optimized conditions, we performed an interaction study for OAT1 and OAT3 using 26 test articles. Some of the test articles showed strong inhibitory potency for the transporters, with IC₅₀ values close to or less than 10 μM. The valid analysis method and optimized systems developed in this study can be utilized to improve the predictability of drug interactions in humans and consequently aid in successful disease treatment by maintaining appropriate systemic exposures.

Model-Based Prediction of Acid Suppression and Proposal of a New Dosing Regimen of Fexuprazan in Humans

Fexuprazan is a potassium-competitive acid blocker (P-CAB). The compounds in this newly developed drug family suppress intragastric acidity. As there are already other acid-suppressing drugs on the market, such as H₂ antagonists and proton pump inhibitors (PPIs), it would be informative to compare the biological effects of fexuprazan against another approved drug with the same indication. The drug concentration predicted by the pharmacokinetic (PK) model could serve as an input function for a pharmacodynamic (PD) model. The apparent pharmacokinetics of fexuprazan could be described by a simpler model. However, a physiologically based pharmacokinetic (PBPK) model was developed in a previous study. A one-compartment model was also proposed in the present study. Both the newly suggested model and the previously validated PBPK model were used as input functions of the PD models. Our simulation revealed that the effects of fexuprazan could be effectively simulated by the proposed PK–PD models. A PK–PD model was also proposed for the oral administration of the PPI reference drug esomeprazole. A model-based analysis was then performed for intragastric pH using several dosing methods. The expected pH could be predicted for both drugs under several dosing regimens using the proposed PK–PD models.

Highly specific chimeric DNA-RNA-guided genome editing with enhanced CRISPR-Cas12a system

The clustered regularly interspaced short palindromic repeats (CRISPR)-Cas12a system is composed of a Cas12a effector that acts as a DNA-cleaving endonuclease and a crispr RNA (crRNA) that guides the effector to the target DNA. It is considered a key molecule for inducing target-specific gene editing in various living systems. Here, we improved the efficiency and specificity of the CRISPR-Cas12a system through protein and crRNA engineering. In particular, to optimize the CRISPR-Cas12a system at the molecular level, we used a chimeric DNA-RNA guide chemically similar to crRNA to maximize target sequence specificity. Compared with the wild-type (wt)-Cas12a system, when using enhanced Cas12a system (en-Cas12a), the efficiency and target specificity improved on average by 2.58 and 2.77 times, respectively. In our study, when the chimeric DNA-RNA-guided en-Cas12a effector was used, the gene-editing efficiency and accuracy were simultaneously increased. These findings could contribute to highly accurate genome editing, such as human gene therapy, in the near future.

In Vivo Toxicity and Pharmacokinetics of Polytetrafluoroethylene Microplastics in ICR Mice

The increased use of plastics has led to severe environmental pollution, particularly by microplastics—plastic particles 5 mm or less in diameter. These particles are formed by environmental factors such as weathering and ultraviolet irradiation, thereby making environmental pollution worse. This environmental pollution intensifies human exposure to microplastics via food chains. Despite potential negative effects, few toxicity assessments on microplastics are available. In this study, two sizes of polytetrafluoroethylene (PTFE) microplastics, approximately 5 μm and 10–50 μm, were manufactured and used for single and four-week repeated toxicity and pharmacokinetic studies. Toxicological effects were comprehensively evaluated with clinical signs, body weight, food and water consumption, necropsy findings, and histopathological and clinical-pathological examinations. Blood collected at 15, 30 60, and 120 min after a single administration of microplastics were analyzed by Raman spectroscopy. In the toxicity evaluation of single and four-week repeated oral administration of PTFE microplastics, no toxic changes were observed. Therefore, the lethal dose 50 (LD₅₀) and no-observed-adverse-effect-level (NOAEL) of PTFE microplastics in ICR mice were established as 2000 mg/kg or more. PTFE microplastics were not detected in blood, so pharmacokinetic parameters could not be calculated. This study provides new insight into the long-term toxicity and pharmacokinetics of PTFE microplastics.

Role of the Efflux Transporters Abcb1 and Abcg2 in the Brain Distribution of Olaparib in Mice

Olaparib is a first-in-class poly (ADP-ribose) polymerase oral inhibitor used to treat various tumors. In this study, we clarified the roles of ABCB1/Abcb1 and ABCG2/Abcg2 transporters in restricting olaparib distribution to the brain. Olaparib was efficiently transported by human ABCG2, human ABCB1, and mouse Abcg2 in vitro. In the in vivo disposition study of olaparib using single or combination knockout mice, the systemic exposure of olaparib did not differ significantly between the strains over an 8-h period. However, the brain-to-plasma unbound concentration ratio of olaparib increased 5.6- and 8.1-fold in Abcb1a/1b and Abcb1a/1b;Abcg2 knockout mice, respectively, compared with wild-type mice. The Abcg2 single knockout mice exhibited a similar brain-to-plasma unbound concentration ratio to wild-type mice. Moreover, the brain distribution of olaparib could be modulated by the ABCB1/ABCG2 dual inhibitor elacridar to reach a similar degree of inhibition to Abcb1a/1b^-/-. These findings suggest that olaparib is actively transported by both human and mouse ABCB1/Abcb1 and ABCG2/Abcg2; while Abcb1a/1b is a major determinant of olaparib brain penetration in mice, Abcg2 is likely to be a minor contributor. Concomitant treatment with temozolomide slightly increased the brain distribution of olaparib in mouse, but the clinical impact of the interaction was expected to be limited.

Interplay among Conformation, Intramolecular Hydrogen Bonds, and Chameleonicity in the Membrane Permeability and Cyclophilin A Binding of Macrocyclic Peptide Cyclosporin O Derivatives

A macrocyclic peptide scaffold with well-established structure-property relationship is desirable for tackling undruggable targets. Here, we adopted a natural macrocycle, cyclosporin O (CsO) and its derivatives (CP1-3), and evaluated the impact of conformation on membrane permeability, cyclophilin A (CypA) binding, and the pharmacokinetic (PK) profile. In nonpolar media, CsO showed a similar conformation to cyclosporin A (CsA), a well-known chameleonic macrocycle, but less chameleonic behavior in a polar environment. The weak chameleonicity of CsO resulted in decreased membrane permeability; however, the more rigid conformation of CsO was not detrimental to its PK profile. CsO exhibited a higher plasma concentration than CsA, which resulted from minimal CypA binding and lower accumulation in red blood cells and moderate oral bioavailability (F = 12%). Our study aids understanding of CsO, a macrocyclic peptide that is less explored than CsA but with greater potential for diversity generation and rational design.

The development of a functional human small intestinal epithelium model for drug absorption

Advanced technologies are required for generating human intestinal epithelial cells (hIECs) harboring cellular diversity and functionalities to predict oral drug absorption in humans and study normal intestinal epithelial physiology. We developed a reproducible two-step protocol to induce human pluripotent stem cells to differentiate into highly expandable hIEC progenitors and a functional hIEC monolayer exhibiting intestinal molecular features, cell type diversity, and high activities of intestinal transporters and metabolic enzymes such as cytochrome P450 3A4 (CYP3A4). Functional hIECs are more suitable for predicting compounds metabolized by CYP3A4 and absorbed in the intestine than Caco-2 cells. This system is a step toward the transition from three-dimensional (3D) intestinal organoids to 2D hIEC monolayers without compromising cellular diversity and function. A physiologically relevant hIEC model offers a novel platform for creating patient-specific assays and support translational applications, thereby bridging the gap between 3D and 2D culture models of the intestine.

Pharmacokinetic Characterization of Supinoxin and Its Physiologically Based Pharmacokinetic Modeling in Rats

Supinoxin is a novel anticancer drug candidate targeting the Y593 phospho-p68 RNA helicase, by exhibiting antiproliferative activity and/or suppression of tumor growth. This study aimed to characterize the in vitro and in vivo pharmacokinetics of supinoxin and attempt physiologically based pharmacokinetic (PBPK) modeling in rats. Supinoxin has good permeability, comparable to that of metoprolol (high permeability compound) in Caco-2 cells, with negligible net absorptive or secretory transport observed. After an intravenous injection at a dose range of 0.5–5 mg/kg, the terminal half-life (i.e., 2.54–2.80 h), systemic clearance (i.e., 691–865 mL/h/kg), and steady state volume of distribution (i.e., 2040–3500 mL/kg) of supinoxin remained unchanged, suggesting dose-independent (i.e., dose-proportional) pharmacokinetics for the dose ranges studied. After oral administration, supinoxin showed modest absorption with an absolute oral bioavailability of 56.9–57.4%. The fecal recovery following intravenous and oral administration was 16.5% and 46.8%, respectively, whereas the urinary recoveries in both administration routes were negligible. Supinoxin was mainly eliminated via NADPH-dependent phase I metabolism (i.e., 58.5% of total clearance), while UDPGA-dependent phase II metabolism appeared negligible in the rat liver microsome. Supinoxin was most abundantly distributed in the adipose tissue, gut, and liver among the nine major tissues studied (i.e., the brain, liver, kidneys, heart, lungs, spleen, gut, muscles, and adipose tissue), and the tissue exposure profiles of supinoxin were well predicted with physiologically based pharmacokinetics.

Development of a Polo-like Kinase-1 Polo-Box Domain Inhibitor as a Tumor Growth Suppressor in Mice Models

Polo-like kinase-1 (Plk1) plays a key role in mitosis and has been identified as an attractive anticancer drug target. Plk1 consists of two drug-targeting sites, namely, N-terminal kinase domain (KD) and C-terminal polo-box domain (PBD). As KD-targeting inhibitors are associated with severe side effects, here we report on the pyrazole-based Plk1 PBD inhibitor, KBJK557, which showed a remarkable in vitro anticancer effect by inducing Plk1 delocalization, mitotic arrest, and apoptosis in HeLa cells. Further, in vivo optical imaging analysis and antitumorigenic activities in mouse xenograft models demonstrate that KBJK557 preferentially accumulates in cancer cells and selectively inhibits cancer cell proliferation. Pharmacokinetic profiles and partition coefficients suggest that KBJK557 was exposed in the blood and circulated through the organs with an intermediate level of clearance (t1/2, 7.73 h). The present investigation offers a strategy for specifically targeting cancer using a newly identified small-molecule inhibitor that targets the Plk1 PBD.

Engineering Yarrowia lipolytica for de novo production of tetraacetyl phytosphingosine

AIMS

To genetically engineer the oleaginous yeast Yarrowia lipolytica for de novo production of tetraacetylphytosphingosine (TAPS), a precursor of phytosphingosine, and optimization of fermentation conditions for high yield.

METHODS AND RESULTS

We successfully constructed a TAPS-producing Y. lipolytica CE3 strain by co-expression of Wickerhamomyces ciferrii-derived acetyl transferases, Sli1p and Atf2p. Next, we optimized several environmental factors including temperature, initial pH and C/N ratio for TAPS production in a shake culture. Deletion of LCB4 in CE3 strain increased the volumetric TAPS titre and cell-specific yield to 142·1 ± 10·7 mg_TAPS  l^-1 and 3·08 ± 0·11 mg_TAPS  g_DCW ^-1 , respectively, in a shake flask culture incubated for 120 h at 28°C with glycerol as the carbon source. Finally, we developed a 5-l fed-batch process with NaOH-mediated pH control and olive oil as a carbon source, exhibiting 650 ± 24 mg_TAPS  l^-1 of TAPS production within 56 h of the fermentation.

CONCLUSIONS

The introduction of codon-optimized Sli1p and Atf2p, deletion of LCB4 gene and sexual hybridization, accompanied by specific fermentation conditions, enhanced TAPS yield in Y. lipolytica.

SIGNIFICANCE AND IMPACT OF THE STUDY

Our results highlight Y. lipolytica as a promising candidate for the industrial production of TAPS, an important component of cosmetic formulations.

Automated Measurements of Key Morphological Features of Human Embryos for IVF

A major challenge in clinical In-Vitro Fertilization (IVF) is selecting the highest quality embryo to transfer to the patient in the hopes of achieving a pregnancy. Time-lapse microscopy provides clinicians with a wealth of information for selecting embryos. However, the resulting movies of embryos are currently analyzed manually, which is time consuming and subjective. Here, we automate feature extraction of time-lapse microscopy of human embryos with a machine-learning pipeline of five convolutional neural networks (CNNs). Our pipeline consists of (1) semantic segmentation of the regions of the embryo, (2) regression predictions of fragment severity, (3) classification of the developmental stage, and object instance segmentation of (4) cells and (5) pronuclei. Our approach greatly speeds up the measurement of quantitative, biologically relevant features that may aid in embryo selection.

Inhibition of Skin Inflammation by Scytonemin, an Ultraviolet Sunscreen Pigment

Scytonemin is a yellow-green ultraviolet sunscreen pigment present in different genera of aquatic and terrestrial blue-green algae, including marine cyanobacteria. In the present study, the anti-inflammatory activities of scytonemin were evaluated in vitro and in vivo. Topical application of scytonemin inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear swelling in BALB/c mice. The expression of tumor necrosis factor-a (TNF-a) and inducible nitric oxide synthase (iNOS) was also suppressed by scytonemin treatment in the TPA-treated ear of BALB/c mice. In addition, scytonemin inhibited lipopolysaccharide (LPS)-induced production of TNF-a and nitric oxide (NO) in RAW 264.7 cells, a murine macrophage-like cell line, and the mRNA expressions of TNF-a and iNOS were also suppressed by scytonemin in LPS-stimulated RAW 264.7 cells. Further study demonstrated that LPS-induced NF-kB activity was significantly suppressed by scytonemin treatment in RAW 264.7 cells. Our results also showed that the degradation of IkBa and nuclear translocation of the p65 subunit were blocked by scytonemin in LPS-stimulated RAW 264.7 cells. Collectively, these results suggest that scytonemin inhibits skin inflammation by blocking the expression of inflammatory mediators, and the anti-inflammatory effect of scytonemin is mediated, at least in part, by down-regulation of NF-kB activity. Our results also suggest that scytonemin might be used as a multi-function skin care ingredient for UV protection and anti-inflammation.

A Machine Learning-Based Identification of Genes Affecting the Pharmacokinetics of Tacrolimus Using the DMETTM Plus Platform

Tacrolimus is an immunosuppressive drug with a narrow therapeutic index and larger interindividual variability. We identified genetic variants to predict tacrolimus exposure in healthy Korean males using machine learning algorithms such as decision tree, random forest, and least absolute shrinkage and selection operator (LASSO) regression. rs776746 (CYP3A5) and rs1137115 (CYP2A6) are single nucleotide polymorphisms (SNPs) that can affect exposure to tacrolimus. A decision tree, when coupled with random forest analysis, is an efficient tool for predicting the exposure to tacrolimus based on genotype. These tools are helpful to determine an individualized dose of tacrolimus.

Neurochemical and behavioral analysis by acute exposure to bisphenol A in zebrafish larvae model

Bisphenol A (BPA) is a chemical monomer widely used in the production of hard plastics for food containers and personal items. Through improper industrial control and disposal, BPA has become a pervasive environmental contaminant, and toxicological studies have shown potent xenobiotic endocrine disruptor activity. Prenatal exposure in particular can lead to infertility and nervous system disorders characterized by behavioral aggression, depression, and cognitive impairment, thus necessitating careful hazard assessment. In this study, we evaluated BPA accumulation rate, blood-brain barrier (BBB) permeability, lethality, cardiotoxicity, behavioral effects, and impacts on multiple neurochemical pathways in zebrafish larvae. The bioconcentration factor (BCF) ranged from 1.95 to 10.0, resulting in a high rate of accumulation in the larval body. Also, high BBB permeability allowed BPA to accumulate at similar rates in both zebrafish and adult mouse (blood to brain concentration ratios of 3.2-6.7 and 1.8 to 5.5, respectively). In addition, BPA-exposed zebrafish larvae exhibited developmental deformities, reduced heart rate, and impaired behavioral patterns, including decreased total distance traveled, slower movement velocity, and altered color-preference. These impairments were associated with inhibition of the phenylalanine to dopamine synthesis pathway and an imbalance between excitatory and inhibitory neurotransmitter systems. Our results suggest that behavioral alteration in BPA-exposed zebrafish result from high accumulation and ensuing dysregulation of serotonergic, kynurenergic, dopaminergic, cholinergic, and GABAergic neurotransmitter systems. In conclusion, similarities in toxic responses to mammalian models highlight the utility of the zebrafish larva as a convenient model for screening environmental toxins.

A physiologically-based pharmacokinetic model adequately predicted the human pharmacokinetic profiles of YH4808, a novel K+-competitive acid blocker

A physiologically-based pharmacokinetic (PBPK) model was developed for YH4808, a novel potassium-competitive acid blocker, using the SimCYP® Simulator based on the physicochemical, in vitro preclinical and clinical data of YH4808. The PBPK model was optimized using YH4808 concentrations obtained from the single-dose phase I clinical trial. Overall, the PBPK model adequately predicted the observed pharmacokinetic profiles of YH4808 in humans. The pharmacokinetic profiles of YH4808 after multiple oral administrations were predicted using a refined PBPK model. The ratios of model-predicted to observed C_max, AUC_inf and AUC_τ values on Day 1 and Day 7 at 100 mg were 0.7-1.0. However, the model failed to predict a decreased exposure after multiple oral administration particularly at higher doses of 200 and 400 mg. The reduced solubility of YH4808 at higher pH was hypothesized as the main cause of the reduction in exposure such that absorption was decreased as pH was increased. This hypothesis was confirmed by PBPK modeling and simulation, where intragastric pH was increased by YH4808.

Determination of Penicillium griseofulvum-oriented pyripyropene A, a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse plasma using liquid chromatography-tandem mass spectrometry and its application to pharmacokinetic studies

In this study, we developed a method for the determination of Penicillium griseofulvum-oriented pyripyropene A (PPPA), a selective inhibitor of acyl-coenzyme A:cholesterol acyltransferase 2, in mouse and human plasma and validated it using liquid chromatography-tandem mass spectrometry. Pyripyropene A (PPPA) and an internal standard, carbamazepine, were separated using a Xterra MS C18 column with a mixture of acetonitrile and 0.1% formic acid as the mobile phase. The ion transitions monitored in positive-ion mode [M + H]+ of multiple-reaction monitoring (MRM) were m/z 148.0 from m/z 584.0 for PPPA and m/z 194.0 from m/z 237.0 for the internal standard. The detector response was specific and linear for PPPA at concentrations within the range from 1 to 5,000 ng/mL. The intra-/inter-day precision and accuracy of the method was acceptable by the criteria for assay validation. The matrix effects of PPPA ranged from 97.6 to 104.2% and from 93.3 to 105.3% in post-preparative mouse and human plasma samples, respectively. PPPA was also stable under various processing and/or handling conditions. Finally, PPPA concentrations in the mouse plasma samples could be measured after intravenous, intraperitoneal, or oral administration of PPPA, suggesting that the assay is useful for pharmacokinetic studies on mice and applicable to human studies.

Model-based pharmacokinetic and pharmacodynamic analysis for acute effects of a small molecule inhibitor of diacylglycerol acyltransferase-1 in the TallyHo/JngJ polygenic mouse

The purpose of this study was to evaluate the acute effect of a small molecule inhibitor of DGAT-1 on triglycerides (TG) and cholesterol in polygenic type 2 diabetic TallyHo/JngJ (TH) mice. PF-04620110, a potent and selective DGAT-1 inhibitor, was used as a model compound in this study and which was administered to TH and ICR mice. The concentration of the model compound that produced 50% of maximum lowering of TG level (IC₅₀) in TH mice was not significantly different from that in ICR mice, when estimated using the model-based pharmacokinetic and pharmacodynamic assay, a two-compartmental model and an indirect response model. The clearance of the inhibitor in TH mice was fivefold higher than that in ICR mice, suggesting significantly altered pharmacokinetics. Moreover, the in vitro metabolic elimination kinetic parameters (k_e,met), determined using liver microsomes from TH and ICR mice were 1.24 ± 0.14 and 0.174 ± 0.116 min^-1, respectively. Thus, we report that the differences in the acute effects of the small molecule DAGT-1 inhibitor between TH mice and ICR mice can be attributed to altered pharmacokinetics caused by an altered metabolic rate for the compound in TH mice.

Identification of metabolites of MDR-1339, an inhibitor of β-amyloid protein aggregation, and kinetic characterization of the major metabolites in rats

We previously reported that MDR-1339, an inhibitor of β-amyloid protein aggregation, was likely to be eliminated by biotransformation in rats. The objective of this study was to determine the chemical identity of metabolites derived from this aggregate inhibitor and to characterize the kinetics of formation of these metabolites in rats. Using high performance liquid chromatography coupled with mass spectrometry with a hybrid triple quadrupole-linear ion trap, 7 metabolites and 1 potential metabolic intermediate were identified in RLM incubations containing MDR-1339. In addition to these, 3 glucuronide metabolites were detected in urine samples from rats receiving a 10 mg/kg oral dose of MDR-1339. When the kinetics of the formation of two major metabolites, M1 and M2, were analyzed assuming simple Michaelis-Menten kinetics, the V_max and K_m values were found to be 0.459 ± 0.0196 nmol/min/mg protein and 28.3 ± 3.07 μM for M1, and 0.101 ± 0.00537 nmol/min/mg protein and 14.7 ± 2.37 μM for M2, respectively. When chemically synthesized M1 and M2 were individually administered to rats intravenously at the dose of 5 mg/kg respectively, the volume of distribution and elimination clearance were determined to be 4590 ± 709 mL/kg and 68.4 ± 5.60 mL/min/kg for M1 and 15300 ± 8110 mL/kg and 98.0 ± 19.5 mL/min/kg for M2, respectively. When MDR-1339 was intravenously administered to rats at a dose of 5 mg/kg, the parent drug and M1 were readily detected for periods of up to 6 h after the administration, but M2 was observed only from 2 to 4 h. A standard moment analysis indicates that the formation clearance of M1 is 6.01 mL/min/kg, suggesting that 19.7% of the MDR-1339 dose was eliminated in rats. These observations indicate that the hepatic biotransformation of MDR-1339 results in the formation of at least 10 metabolites and that M1 is the major metabolite derived from this aggregation inhibitor in rats.

Nonocclusive Mesenteric Ischaemia Induced by Diltiazem Overdose: A Case Report

Acute mesenteric ischaemia is a rare complication of calcium channel blocker (CCB) overdose. A previous study reported a case of mesenteric ischaemia induced by poisoning with CCBs other than diltiazem. We present a case of nonocclusive mesenteric ischaemia (NOMI) induced by diltiazem poisoning. Through this case report, we wish to emphasize that the clinicians should keep the possibility of intestinal ischaemia in mind from the early phase of calcium channel blocker poisoning. In addition, close monitoring and intense abdominal examination including the abdominal computed tomography scan should be done if CCBs poisoning patients complained of an abdominal pain.

Bacterial Contamination of Computer and Hand Hygiene Compliance in the Emergency Department

Introduction

The aim of this study was to determine the degree and nature of bacterial contamination of computer equipment in three Korean emergency departments (ED).

Methods

Hand hygiene practices of ED doctors and nurses were observed before contact with computer equipment. Microbiological swab samples were obtained from 112 multiple-user computer keyboards and electronic mice in the ED of three teaching hospitals. Isolated organisms were identified by a clinical microbiologist using Gram stain, colony morphology, and susceptibility test.

Results

Of the 112 samples, 103 (92.0%) showed growth of organisms on culture. Thirty-eight (33.9%) pieces of computer equipment yielded multiple bacterial species. Coagulase-negative Staphylococcus was the most common microorganism isolated (85.7%). Methicillin-resistant Staphylococcus aureus was obtained from two keyboards in two hospitals (1.8%). Hand hygiene compliance was observed on 29.9% occasions. Hand hygiene compliance after patient contact (38.0%) was higher than after other environmental contact (20.7%).

Conclusions

Multiple user computer equipment in the ED may serve as reservoirs for nosocomial infection. Hand hygiene should be performed before and after using all ED equipment, including computer equipment.

Bacterial Contamination of Computer and Hand Hygiene Compliance in the Emergency Department

Introduction

The aim of this study was to determine the degree and nature of bacterial contamination of computer equipment in three Korean emergency departments (ED).

Methods

Hand hygiene practices of ED doctors and nurses were observed before contact with computer equipment. Microbiological swab samples were obtained from 112 multiple-user computer keyboards and electronic mice in the ED of three teaching hospitals. Isolated organisms were identified by a clinical microbiologist using Gram stain, colony morphology, and susceptibility test.

Results

Of the 112 samples, 103 (92.0%) showed growth of organisms on culture. Thirty-eight (33.9%) pieces of computer equipment yielded multiple bacterial species. Coagulase-negative Staphylococcus was the most common microorganism isolated (85.7%). Methicillin-resistant Staphylococcus aureus was obtained from two keyboards in two hospitals (1.8%). Hand hygiene compliance was observed on 29.9% occasions. Hand hygiene compliance after patient contact (38.0%) was higher than after other environmental contact (20.7%).

Conclusions

Multiple user computer equipment in the ED may serve as reservoirs for nosocomial infection. Hand hygiene should be performed before and after using all ED equipment, including computer equipment. (Hong Kong j.emerg.med. 2012;19:387-393)

Pharmacokinetics of tafamidis, a transthyretin amyloidosis drug, in rats

1. We characterized the pharmacokinetics of tafamidis, a novel drug to treat transthyretin-related amyloidosis, in rats after intravenous and oral administration at doses of 0.3-3 mg/kg. In vitro Caco-2 cell permeability and liver microsomal stability, as well as in vivo tissue distribution and plasma protein binding were also examined. 2. After intravenous injection, systemic clearance (CL), volumes of distribution at steady state (V_ss) and half-life (T_½) remained unaltered as a function of dose, with values in the ranges of 6.41-7.03 mL/h/kg, 270-354 mL/kg and 39.5-46.9 h, respectively. Following oral administration, absolute bioavailability was 99.7-104% and was independent of doses from 0.3 to 3 mg/kg. In the urine and faeces, 4.36% and 48.9% of tafamidis, respectively, were recovered. 3. Tafamidis was distributed primarily in the liver and not in the brain, kidney, testis, heart, spleen, lung, gut, muscle, or adipose tissue. Further, tafamidis was very stable in rat liver microsomes, and its plasma protein binding was 99.9%. 4. In conclusion, tafamidis showed dose-independent pharmacokinetics with intravenous and oral doses of 0.3-3 mg/kg. Tafamidis undergoes minimal first-pass metabolism, distributes mostly in the liver and plasma, and appears to be eliminated primarily via biliary excretion.

Zebrafish as a Screening Model for Testing the Permeability of Blood-Brain Barrier to Small Molecules

The objective of this study was to evaluate the permeability of small molecules into the brain via the blood-brain barrier in zebrafish and to investigate the possibility of using this animal model as a screening tool during the early stages of drug discovery. Fifteen compounds were used to understand the permeation into the brain in zebrafish and mice. The ratio of brain-to-plasma concentration was compared between the two animal models. The partition coefficient (K_p,brain), estimated using the concentration ratio at designated times (0.167, 0.25, 0.5, or 2 h) after oral administrations (per os, p.o), ranged from 0.099 to 5.68 in zebrafish and from 0.080 to 11.8 in mice. A correlation was observed between the K_p,brain values obtained from the zebrafish and mice, suggesting that zebrafish can be used to estimate K_p,brain to predict drug penetration in humans. Furthermore, in vivo transport experiments to understand the permeability glycoprotein (P-gp) transporter-mediated behavior of loperamide (LPM) in zebrafish were performed. The zebrafish, K_{p,brain,30min} of LPM was determined to be 0.099 ± 0.069 after dosing with LPM alone, which increased to 0.180 ± 0.115 after dosing with LPM and tariquidar (TRQ, an inhibitor of P-gp). In mouse, the K_{p,brain,30min} of LPM was determined to be 0.080 ± 0.004 after dosing with LPM alone and 0.237 ± 0.013 after dosing with LPM and TRQ. These findings indicate that the zebrafish could be used as an effective screening tool during the discovery stages of new drugs to estimate their distribution in the brain.

Specific Inhibition of the Distribution of Lobeglitazone to the Liver by Atorvastatin in Rats: Evidence for a Rat Organic Anion Transporting Polypeptide 1B2-Mediated Interaction in Hepatic Transport

Cytochrome P450 enzymes and human organic anion transporting polypeptide (OATP) 1B1 are reported to be involved in the pharmacokinetics of lobeglitazone (LB), a new peroxisome proliferator-activated receptor γ agonist. Atorvastatin (ATV), a substrate for CYP3A and human OATP1B1, is likely to be coadministered with LB in patients with the metabolic syndrome. We report herein on a study of potential interactions between LB and ATV in rats. When LB was administered intravenously with ATV, the systemic clearance and volume of distribution at steady state for LB remained unchanged (2.67 ± 0.63 ml/min per kg and 289 ± 20 ml/kg, respectively), compared with that of LB without ATV (2.34 ± 0.37 ml/min per kg and 271 ± 20 ml/kg, respectively). Although the tissue-to-plasma partition coefficient (K_p) of LB was not affected by ATV in most major tissues, the liver K_p for LB was decreased by ATV coadministration. Steady-state liver K_p values for three levels of LB were significantly decreased as a result of ATV coadministration. LB uptake was inhibited by ATV in rat OATP1B2-overexpressing Madin-Darby canine kidney cells and in isolated rat hepatocytes in vitro. After incorporating the kinetic parameters for the in vitro studies into a physiologically based pharmacokinetics model, the characteristics of LB distribution to the liver were consistent with the findings of the in vivo study. It thus appears that the distribution of LB to the liver is mediated by the hepatic uptake of transporters such as rat OATP1B2, and carrier-mediated transport is involved in the liver-specific drug-drug interaction between LB and ATV in vivo.

Pharmacokinetics of enzalutamide, an anti-prostate cancer drug, in rats

We characterized the pharmacokinetics of enzalutamide, a novel anti-prostate cancer drug, in rats after intravenous and oral administration in the dose range 0.5-5 mg/kg. Tissue distribution, liver microsomal stability, and plasma protein binding were also examined. After intravenous injection, systemic clearance, volumes of distribution at steady state (Vss), and half-life (T½) remained unaltered as a function of dose, with values in the ranges of 80.4-86.3 mL/h/kg, 1020-1250 mL/kg, and 9.13-10.6 h, respectively. Following oral administration, absolute oral bioavailability was 89.7 % and not dose-dependent. The recoveries of enzalutamide in urine and feces were 0.0620 and 2.04 %, respectively. Enzalutamide was distributed primarily in 10 tissues (brain, liver, kidneys, testis, heart, spleen, lungs, gut, muscle, and adipose) and tissue-to-plasma ratios of enzalutamide ranged from 0.406 (brain) to 10.2 (adipose tissue). Further, enzalutamide was stable in rat liver microsomes, and its plasma protein binding was 94.7 %. In conclusion, enzalutamide showed dose-independent pharmacokinetics at intravenous and oral doses of 0.5-5 mg/kg. Enzalutamide distributed primarily to 10 tissues and appeared to be eliminated primarily by metabolism.

In vitro and in vivo anti-inflammatory effects of a novel 4,6-bis ((E)-4-hydroxy-3-methoxystyryl)-1-phenethylpyrimidine-2(1H)-thione

Inflammation plays a critical defensive role in the human body. However, uncontrolled or aberrant inflammatory responses contribute to various acute and chronic diseases. The Nrf2-ARE pathway plays a pivotal role in the regulation of inflammatory markers, such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). On the basis of this concept, we synthesized a novel anti-inflammatory 4,6-bis ((E)-4-hydroxy-3-methoxystyryl)-1-phenethylpyrimidine-2(1H)-thione (HPT), and in vitro experiments using HepG2-C8 ARE-luciferase-transfected cells demonstrated the induction of Nrf2-ARE activity. In lipopolysaccharide (LPS)-induced RAW 264.7 cells, HPT treatment reduced the production of nitric oxide (NO) as well as the protein and mRNA expression levels of COX-2 and iNOS, in a dose-dependent manner. In addition, HPT suppressed the mRNA expression of inflammatory cytokines, including tumor necrosis factor-α (TNF-α), interleukin (IL)-1β, and IL-6. In LPS-induced macrophages, HPT inhibited COX-2 and iNOS by blocking the activation of p38 and c-Jun NH2-terminal kinase (JNK) but not extracellular signal-regulated kinase (ERK1/2). Furthermore, an in vivo anti-inflammatory study was performed using a TPA-induced skin inflammation mouse model, and the results showed that HPT reduced TPA-induced inflammation and attenuated the expression of COX-2 and iNOS in TPA-induced mouse skin tissue. Thus, HPT demonstrated anti-inflammatory activity both in LPS-induced RAW 264.7 cells and TPA-stimulated mouse skin and may therefore serve as a potential anti-inflammatory agent.

Decoupling free-carriers contributions from oxygen-vacancy and cation-substitution in extrinsic conducting oxides

The intrinsic oxygen-vacancies and the extrinsic dopants are two major fundamental free-carrier sources for the extrinsic conducting oxides, such as Sn-doped In(2)O(3). Yet, the individual contributions of the above two free-carrier sources to the total carrier concentrations have never been unraveled. A carrier-concentration separation model is derived in this work, which can define the individual contributions to the total carrier concentration from the intrinsic oxygen-vacancies and the extrinsic dopants, separately. The individual contributions obtained from the present carrier-concentration separation model are verified by the two-state trapping model, photoluminescence, and positron annihilation lifetime (PAL) spectroscopy. In addition, the oxygen-vacancy formation energy of the Sn:In(2)O(3) thin film is determined to be 0.25 eV by PAL spectroscopy.

Determination of 2-aryl-7(3',4'-dialkoxyphenyl)-pyrazolo [1,5-alpha] pyrimidine, a novel phosphodiesterase-4 inhibitor, in rat plasma by liquid chromatography-tandem mass spectrometry

A method for assaying a novel phosphodiesterase-4 inhibitor, 2-aryl-7(3',4'-dialkoxyphenyl)-pyrazolo [1,5-alpha] pyrimidine (PDE-310), was developed and validated in rat plasma using liquid chromatography-tandem mass spectrometry (LC-MS-MS). Rat plasma samples were processed by liquid-liquid extraction with ethyl acetate and injected onto the LC-MS-MS system for quantification. PDE-310 and imipramine (i.e., internal standard) were separated using a Gemini C18 column with mixture of acetonitrile and 0.1% formic acid (70:30, v/v) as the mobile phase. The ion transitions monitored were m/z 425.0 → 331.0 for PDE-310 and m/z 281.3 → 86.1 for imipramine in the multiple-reaction monitoring mode. The detector response was specific and linear for PDE-310 concentrations in the range of 0.1-50 µg/mL. The intra-day and inter-day precision and accuracy of the method were determined to be within the acceptance criteria for assay validation guidelines. The recoveries were approximately 85.7 and 88.2% from rat plasma for PDE-310 and imipramine, respectively. PDE-310 was stable under various processing and handling conditions. PDE-310 concentrations were readily measured in rat plasma samples up to 8 h after an intravenous administration of PDE-310, suggesting that the assay is practically useful.

Pharmacokinetics and pharmacodynamics of KR-66223, a novel DPP-4 inhibitor

KR-66223 is a novel dipeptidyl peptidase-4 (DPP-4) inhibitor that is under development for the treatment of type 2 diabetes. We studied the pharmacokinetic and pharmacodynamic characteristics of KR-66223 in rats, monkeys, and dogs to predict PK/PD profiles in humans. KR-66223 exhibited a moderate volume of distribution (0.3-1.8 L/kg), moderate systemic clearance (1-1.76 L/h/kg), long half-life (>3 h), and low oral bioavailability (below 2.5% in all tested species). The EC(50)s for DPP-4 inhibition as calculated by the E(max) model was below 4.25 ng/mL across all species, confirming KR-66223 as a potent DPP-4 inhibitor. In vitro plasma protein binding suggested that it was available (69-89%), correlating with its volume of distribution in animals. Using allometric scaling and the E(max) model, human systemic clearance, volume of the central compartment, volume of the peripheral compartment, and EC₅₀ for DPP-4 inhibition were predicted to be 0.31 L/h/kg, 0.1 L/kg, 2.4 L/kg, and 3 ng/mL, respectively. These results can serve as a valuable foundation for future clinical trials.