ABSTRACT
KEY MESSAGE: EgMADS3, a pivotal transcription factor, positively regulates MCFA accumulation via binding to the EgLPAAT promoter, advancing lipid content in mesocarp of oil palm. Lipids function as the structural components of cell membranes, which serve as permeable barriers to the external environment of cells. The medium-chain fatty acid in the stored lipids of plants is an important renewable energy. Most research on MCFA production in plant lipid synthesis is based on biochemical methods, and the importance of transcriptional regulation in MCFA synthesis and its incorporation into TAGs needs further research. Oil palm is the most productive oil crop in the world and has the highest productivity among the main oil crops. In this study, the MADS transcription factor (EgMADS3) in the mesocarp of oil palm was characterized. Through the VIGS-virus induced gene silencing, it was determined that the potential target gene of EgMADS3 was related to the biosynthesis of medium-chain fatty acid (MCFA). Transient transformation in protoplasts and qRT-PCR analysis showed that EgMADS3 positively regulated the expression of EgLPAAT. The results of the yeast one-hybrid assays and EMSA indicated the interaction between EgMADS3 and EgLPAAT promoter. Through genetic transformation and fatty acid analysis, it is concluded that EgMADS3 directly regulates the mid-chain fatty acid synthesis pathway of the potential target gene EgLPAAT, thus promotes the accumulation of MCFA and improves the total lipid content. This study is innovative in the functional analysis of the MADS family transcription factor in the metabolism of medium-chain fatty acids (MCFA) of oil palm, provides a certain research basis for improving the metabolic pathway of chain fatty acids in oil palm, and improves the synthesis of MCFA in plants. Our results will provide a reference direction for further research on improving the oil quality through biotechnology of oil palm.
Subject(s)
Arecaceae , Arecaceae/genetics , Arecaceae/metabolism , Fatty Acids/metabolism , Transcription Factors/genetics , Transcription Factors/metabolism , Metabolic Networks and Pathways , Palm Oil/metabolismABSTRACT
During spaceflight, the cardiovascular system undergoes remarkable adaptation to microgravity and faces the risk of cardiac remodeling. Therefore, the effects and mechanisms of microgravity on cardiac morphology, physiology, metabolism, and cellular biology need to be further investigated. Since China started constructing the China Space Station (CSS) in 2021, we have taken advantage of the Shenzhou-13 capsule to send human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) to the Tianhe core module of the CSS. In this study, hPSC-CMs subjected to space microgravity showed decreased beating rate and abnormal intracellular calcium cycling. Metabolomic and transcriptomic analyses revealed a battery of metabolic remodeling of hPSC-CMs in spaceflight, especially thiamine metabolism. The microgravity condition blocked the thiamine intake in hPSC-CMs. The decline of thiamine utilization under microgravity or by its antagonistic analog amprolium affected the process of the tricarboxylic acid cycle. It decreased ATP production, which led to cytoskeletal remodeling and calcium homeostasis imbalance in hPSC-CMs. More importantly, in vitro and in vivo studies suggest that thiamine supplementation could reverse the adaptive changes induced by simulated microgravity. This study represents the first astrobiological study on the China Space Station and lays a solid foundation for further aerospace biomedical research. These data indicate that intervention of thiamine-modified metabolic reprogramming in human cardiomyocytes during spaceflight might be a feasible countermeasure against microgravity.
Subject(s)
Pluripotent Stem Cells , Weightlessness , Humans , Metabolic Reprogramming , Myocytes, Cardiac/metabolism , Calcium/metabolism , Cell Differentiation , Pluripotent Stem Cells/metabolismABSTRACT
ABSTRACT: Tumor chemoprevention and treatment are two approaches aimed at improving the survival of patients with cancers. An ideal anti-tumor drug is that which not only kills tumor cells but also alleviates tumor-causing risk factors, such as precancerous lesions, and prevents tumor recurrence. Chinese herbal monomers are considered to be ideal treatment agents due to their multi-target effects. Astragaloside has been shown to possess tumor chemoprevention, direct anti-tumor, and chemotherapeutic drug sensitization effects. In this paper, we review the effects of astragaloside on tumor prevention and treatment and provide directions for further research.
Subject(s)
Antineoplastic Agents , Neoplasms , Saponins , Triterpenes , Humans , Chemoprevention , Neoplasms/drug therapy , Neoplasms/prevention & control , Saponins/therapeutic use , Saponins/pharmacology , Triterpenes/therapeutic use , Triterpenes/pharmacologyABSTRACT
Theranostic nanoplatforms with accurate diagnosis and effective therapy show a bright prospect for tumor treatments. Herein, a novel boracic acid-modified graphite carbon nitride and Prussian blue nanohybrid (PB@B-g-C3N4) was developed, which provides sialic acid-targeted Raman recognition and synergistic photothermal/photodynamic therapy in the near-infrared region. Owing to the specific interaction between boracic acid and sialic acid and Raman response at 2157 cm-1 of PB, the nanohybrids exhibit high specificity and Raman sensitivity for detection of the overexpressed sialic acid on tumor cells. Moreover, the photothermal conversion efficiency of PB@B-g-C3N4 is as high as 47.0% with 808 nm laser irradiation due to the enhanced absorbance of PB@B-g-C3N4. PB@B-g-C3N4 also possesses excellent photodynamic activity, which is attributed to the energy transfer of PB (type I) and electron transfer between PB and B-g-C3N4 (type II). This nanotheranostic agent for Raman recognition of cancer markers and synergistic photothermal/photodynamic therapy holds great potential for the development of efficient theranostic nanoplatforms.
Subject(s)
Neoplasms , Photochemotherapy , Ferrocyanides , Humans , N-Acetylneuraminic Acid , Neoplasms/therapy , Phototherapy/methodsABSTRACT
In this work, a new type of micromesoporous substance was prepared with fatty alcohol-polyoxyethylene ether (AEO) surfactant freezing penetration and pyrolysis using shells as raw materials. The obtained material exhibited good adsorbability and could be added to oil-contaminated soil to adsorb the pollutant, which resulted in the regeneration of the initially polluted soil. It was determined that the main component of the developed substance was CaCO3. Importantly, the conducted experiments revealed that the obtained mussel micromesoporous material displayed certain adsorption effects toward petroleum hydrocarbons in a diesel solution. Moreover, it was found that chemical adsorption was more optimal than physical adsorption. The soil remediation effect was the best when the content of the mussel micromesoporous material in the soil was 400â g/kg. Under these conditions, the removal rate of petroleum hydrocarbon was established at 49.38%. This study indicated that micromesoporous material has great potential in the application of oil contaminated soil remediation.
Subject(s)
Bivalvia , Environmental Restoration and Remediation , Petroleum Pollution , Petroleum , Soil Pollutants , Animals , Biodegradation, Environmental , Hydrocarbons , Porosity , Soil/chemistry , Soil Pollutants/analysisABSTRACT
Psoralen ultraviolet A (PUVA) therapy has thrived as a promising treatment for psoriasis. However, overdose of PUVA treatment will cause side-effects, such as melanoma formation. And these side-effects are often ignored during PUVA therapy. Hence, in situ monitoring therapeutic response of PUVA therapy is important to minimize side-effects. Aberrant expression of tyrosinase (TYR) has been proved to be associated with melanoma, indicating that TYR is a potential target for evaluation of PUVA therapy. Herein, we reported a strategy for in situ monitoring TYR activity during PUVA therapy by using a cell-array chip-based SERS platform. The cell-array chip was used to simulate cell survival environment for cell culture. Capture of single cells and living cell analysis were realized in the isolated microchambers. An enzyme-induced core-shell self-assembly substrate was used to evaluate TYR activity in living cells during PUVA therapy. The gold nanoparticle modified with a SERS reporter, 4-mercaptobenzonitrile (4-MBN), was used as the core. In the presence of oxygen and TYR, hydroxylation of l-tyrosine occurred, leading to the reduction of silver ion on the surface of gold cores. The growth of silver shells was accompanied by the increased SERS intensity of the reporter, which is related directly to TYR activity. The detection limit for TYR activity is 0.45 U/mL. Upregulation of TYR activity was successfully monitored after PUVA therapy. Notably, real-time and in situ information of therapeutic response can be obtained through monitoring PUVA therapy by using a cell-array chip-based SERS platform, which has great potential to guide the clinical application of PUVA therapy.
Subject(s)
Gold , Metal Nanoparticles , PUVA Therapy , Animals , Cell Line , Mice , Silver , Spectrum Analysis, RamanABSTRACT
Roughness is an important parameter in hydrodynamic and water quality modelling; it has direct effects on bottom shear stress which relied on sediment and vegetation. The varied roughness caused by spatial heterogeneity of sediment and vegetation may lead to uncertain simulation results. To investigate the effect of roughness uncertainty on the performance of hydrodynamic water quality models, a typical large shallow lake in China (Lake Taihu) was divided into eight areas for illustrating the effect of spatial variation of roughness on hydrodynamics and water quality. Total nitrogen (TN) was selected as the variable to calculate the uncertainty interval, and sensitive positions greatly affected by roughness as well as the appropriate range of roughness were explored by means of regional sensitive analysis (RSA). The results showed that roughness had the most significant effect on the bottom velocity. The uncertainty for water quality caused by roughness presented a striking spatial difference; the uncertainty interval for TN could be up to 1.3 mg/L. The posterior distribution of roughness was given to further narrowed the range of roughness, and the updated roughness range manifested that roughness value should be set higher in the area with thick sediment and abundant vegetation. It is of utmost importance to consider the comprehensive effects of sediment and vegetation in the determination of roughness. For certain lake areas with great water quality simulation error, the error could be effectively reduced by setting spatial distributed roughness. The optimization scheme was provided for the reasonable determination of roughness, so that the dynamic characteristic at the sediment-water interface could be represented synthetically. In this paper, the uncertainty and sensitivity of roughness in hydrodynamic water quality model are analyzed to provide reference for parameter setting of large shallow water lake model. For large scale lakes, parameters need to be modified according to the actual condition due to the spatial difference of friction coefficient at the bottom.
Subject(s)
Hydrodynamics , Water Quality , China , Environmental Monitoring , Geologic Sediments , Phosphorus/analysis , UncertaintyABSTRACT
Drugs that prolong QT may cause torsade de pointes (TdP). However, translation of nonclinical assessment of QT prolongation or hERG channel, targeted by QT-prolonging drugs, into clinical TdP risk has been insufficient to date. In this blinded study, we confirmed the utility of a Normalized TdP Score System in predicting drug-induced TdP risks among 34 drugs, including 28 with low, intermediate, and high TdP risks under the Comprehensive In Vitro Proarrhythmia Assay (CiPA) initiative plus six compounds with names blinded to the investigators, using the rabbit ventricular wedge assay. Concentration-dependent TdP scores were determined by drug-induced changes in QT, Tp-e , and proarrhythmias. Disclosure of the names and testing concentrations was made after completion of the experiments and report to the sponsors. Drugs' normalized TdP scores were calculated thereafter based on their respective free clinical maximum concentration (Cmax ). Drugs' normalized TdP scores were calculated and ranked for 33 drugs, excluding 1 investigational drug, and the TdP risks of the 28 CiPA drugs were correctly distinguished according to their respective categories of low, intermediate, and high TdP risks under the CiPA initiative. Accordingly, we are able to propose the cutoff values of the normalized TdP scores at 1 × Cmax : ≤ 0, > 0 to < 0.65 and ≥ 0.65, respectively, for low, intermediate, and high risk. This blinded study supports utility of our Normalized TdP Score System in predicting drug-induced TdP risks in 33 drugs, including 28 used for characterization of other assays under the CiPA initiative. However, these results need to be replicated in other laboratories.
Subject(s)
Arrhythmias, Cardiac/chemically induced , Arrhythmias, Cardiac/epidemiology , Torsades de Pointes/chemically induced , Torsades de Pointes/epidemiology , Animals , Drug Evaluation, Preclinical , Electrocardiography , Heart Ventricles/physiopathology , Long QT Syndrome/chemically induced , Rabbits , Risk AssessmentABSTRACT
The recycling of waterworks sludge has become a trending issue because it not only solves the problem of difficult disposal but also saves land resources. This paper aimed to provide a new idea for the utilization of waterworks sludge to form ceramsite and to purify sewage. The specific surface area, average pore size, and pore volume of the made ceramsite were 8.15 m2/g, 8.53 nm, and 1.88 cm2/g, respectively. The made ceramsite was applied in a vertical-flow constructed wetland, and the removal efficiency of nitrogen, phosphorus and organic matter in sewage were investigated under the conditions of different start-up periods, hydraulic retention times, matrix filling heights and water quality. The removal rates of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), and total phosphorus (TP) in the constructed wetlands were stable at 70%, 60%, and 79%, respectively. This constructed wetland with a ceramic matrix has certain advantages in the total amount of denitrifying microorganisms, with a proportion of 14.92%. The results prove the feasibility of preparing ceramsite from waterworks sludge and applying it as a matrix in a constructed wetland to purify sewage.
Subject(s)
Ammonia/metabolism , Complex Mixtures , Nitrogen/metabolism , Phosphorus/metabolism , Recycling/methods , Sewage , Waste Disposal, Fluid/methods , Biological Oxygen Demand Analysis , Carbon , Denitrification , Iron , WetlandsSubject(s)
Drug Development/organization & administration , Prescription Drugs/pharmacology , Prescription Drugs/therapeutic use , United States Food and Drug Administration/organization & administration , Drug Evaluation, Preclinical/methods , Endpoint Determination , Humans , Models, Statistical , Prescription Drugs/adverse effects , Prescription Drugs/pharmacokinetics , Product Surveillance, Postmarketing , Research Design , United StatesABSTRACT
Melatonin (N-acetyl-5-methoxytryptamine) is a derivative of tryptophan which is produced and secreted mainly by the pineal gland and regulates a variety of important central and peripheral actions. To examine the potential effects of melatonin on the proliferation and differentiation of bovine intramuscular preadipocytes (BIPs), BIPs were incubated with different concentrations of melatonin. Melatonin supplementation at 1 mM significantly increased peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer-binding protein (C/EBP) ß, and C/EBPα expression and promoted the differentiation of BIPs into adipocytes with large lipid droplets and high cellular triacylglycerol (TAG) levels. Melatonin also significantly enhanced lipolysis and up-regulated the expression of lipolytic genes and proteins, including hormone sensitive lipase (HSL), adipocyte triglyceride lipase (ATGL), and perilipin 1 (PLIN1). Moreover, melatonin reduced intracellular reactive oxygen species (ROS) levels by increasing the expression levels and activities of superoxide dismutase 1 (SOD1) and glutathione peroxidase 4 (GPX4). Finally, the positive effects of melatonin on adipogenesis, lipolysis, and redox status were reversed by treatment with luzindole, anantagonist of nonspecific melatonin receptors 1 (MT1) and 2 (MT2), and 4-phenyl-2-propionamidotetraline (4P-PDOT), a selective MT2 antagonist. These results reveal that melatonin promotes TAG accumulation via MT2 receptor during differentiation in BIPs.
Subject(s)
Adipocytes/drug effects , Cell Differentiation/drug effects , Melatonin/pharmacology , Receptor, Melatonin, MT2/metabolism , Triglycerides/metabolism , Adipocytes/cytology , Adipocytes/metabolism , Adipogenesis/genetics , Animals , Cattle , Cell Differentiation/genetics , Cells, Cultured , Gene Expression Regulation/drug effects , Lipase/genetics , Lipase/metabolism , Lipolysis/genetics , Male , Perilipin-1/genetics , Perilipin-1/metabolism , Receptor, Melatonin, MT2/antagonists & inhibitors , Tetrahydronaphthalenes/pharmacologyABSTRACT
Objective To investigate the effect of iron overload on biological activity and apoptosis in Huh7.5 cells. Methods Huh7.5 cells were cultured in the medium supplemented with 50, 100, 200 µmol/L ferric ammonium citrate (FAC). Fluorescence microscopy was employed to determine cell iron load labeled by Phen Green FL; proliferation activity of Huh7.5 cells was evaluated by MTT assay; protein and mRNA levels of transferrin receptor (TfR1), TfR2, divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) in Huh7.5 cells were detected by Western blotting and real-time PCR, respectively; cell reactive oxygen species (ROS) labeled by dichlorofluorescin diacetate (DCFH-DA) and cell apoptosis labeled by annexinV-FITC/PI were analyzed by flow cytometry. Results FAC treatment increased intracellular iron load in a dose-dependent manner. Compared with control group, mRNA and protein expressions of TfR1, TfR2 and DMT1 were down-regulated, while mRNA and protein expression of FPN1 was significantly up-regulated in FAC treated groups. With the increasing dose of FAC, intracellular ROS level increased significantly and cell proliferation activity decreased significantly. The cell apoptosis rate in FAC treated groups were remarkably higher than that in control group, but after antioxidant N-acetylcysteine (NAC) was added, the cell apoptosis in FAC treated group was inhibited obviously. Conclusion Iron overload can inhibit the proliferation and promote the apoptosis of Huh7.5 cells through oxidative stress.
Subject(s)
Apoptosis , Hepatocytes/pathology , Iron Overload/pathology , Acetylcysteine/pharmacology , Cation Transport Proteins/analysis , Cell Line, Tumor , Cell Proliferation , Hepatitis C, Chronic/therapy , Hepatocytes/metabolism , Humans , Iron Overload/metabolism , Oxidative Stress , Receptors, Transferrin/analysisABSTRACT
On December 11, 2015, the FDA approved uridine triacetate (VISTOGARD; Wellstat Therapeutics Corporation) for the emergency treatment of adult and pediatric patients following a fluorouracil or capecitabine overdose regardless of the presence of symptoms, and of those who exhibit early-onset, severe, or life-threatening toxicity affecting the cardiac or central nervous system, and/or early onset, unusually severe adverse reactions (e.g., gastrointestinal toxicity and/or neutropenia) within 96 hours following the end of fluorouracil or capecitabine administration. Uridine triacetate is not recommended for the nonemergent treatment of adverse reactions associated with fluorouracil or capecitabine because it may diminish the efficacy of these drugs, and the safety and efficacy of uridine triacetate initiated more than 96 hours following the end of administration of these drugs has not been established. The approval is based on data from two single-arm, open-label, expanded-access trials in 135 patients receiving uridine triacetate (10 g or 6.2 g/m(2) orally every 6 hours for 20 doses) for fluorouracil or capecitabine overdose, or who exhibited severe or life-threatening toxicities within 96 hours following the end of fluorouracil or capecitabine administration. Ninety-six percent of patients met the major efficacy outcome measure, which was survival at 30 days or survival until the resumption of chemotherapy, if prior to 30 days. The most common adverse reactions were vomiting, nausea, and diarrhea. This article summarizes the FDA review of this New Drug Application, the data supporting approval of uridine triacetate, and the unique regulatory situations encountered by this approval. Clin Cancer Res; 22(18); 4545-49. ©2016 AACR.
Subject(s)
Acetates/pharmacology , Acetates/therapeutic use , Antineoplastic Agents/pharmacology , Antineoplastic Agents/therapeutic use , Drug Approval , Neoplasms/therapy , Uridine/analogs & derivatives , Acetates/chemistry , Animals , Antineoplastic Agents/chemistry , Capecitabine/administration & dosage , Capecitabine/adverse effects , Clinical Trials as Topic , Drug Evaluation, Preclinical , Fluorouracil/administration & dosage , Fluorouracil/adverse effects , Humans , Neoplasms/diagnosis , Prescription Drug Overuse , Research Design , Treatment Outcome , United States , United States Food and Drug Administration , Uridine/chemistry , Uridine/pharmacology , Uridine/therapeutic useABSTRACT
Numerous cytokines participate in the occurrence and development of inflammation and renal interstitial fibrosis. Previous studies confirmed that TGF-ß1 overexpressed in diabetic nephropathy. As a downstream signal protein of TGF-ß1 family, SMAD has an important role in the process of α-SMA mediated renal interstitial fibrosis. This study aimed to study astragaloside effect on TGF-ß1, SMAD2/3, and α-SMA expression in the kidney tissue of diabetic KKAy mice, to reveal its potential impact on renal interstitial fibrosis. 20 type II diabetic KKAy mice were randomly equally divided into model group and astragaloside group, while 10 male C57BL/6J mice were selected as the control. Astragaloside at 40 mg/(kgâ¢d) was given when the KKAy mice fed with high-fat diet to 14 weeks old. The mice were killed at 24 weeks old and the kidney tissue samples were collected. Pathology morphological changes were observed. TGF-ß1, SMAD2/3, and α-SMA expression levels were determined by immunohistochemistry. Compared with control, mice kidney in model group appeared obvious fibrosis and up-regulated blood glucose level, TGF-ß1, SMAD2/3, and α-SMA expression (P < 0.05). Mice in astragaloside group exhibited alleviated renal interstitial fibrosis compared with the model. Its blood glucose level, TGF-ß1, SMAD2/3, and α-SMA expression levels were significantly lower than the model group (P < 0.05). Astragaloside can delay the renal fibrosis process in diabetic mice by influencing the TGF-ß/SMADS signaling pathway and down-regulating TGF-ß1, SMAD2/3, and α-SMA expression.
Subject(s)
Actins/metabolism , Astragalus propinquus , Diabetes Mellitus/drug therapy , Diabetic Nephropathies/prevention & control , Drugs, Chinese Herbal/pharmacology , Kidney/drug effects , Smad2 Protein/metabolism , Smad3 Protein/metabolism , Transforming Growth Factor beta1/metabolism , Animals , Astragalus propinquus/chemistry , Diabetes Mellitus/metabolism , Diabetic Nephropathies/etiology , Diabetic Nephropathies/metabolism , Diabetic Nephropathies/pathology , Disease Models, Animal , Drugs, Chinese Herbal/isolation & purification , Fibrosis , Kidney/metabolism , Kidney/pathology , Male , Mice, Inbred C57BL , Phytotherapy , Plants, Medicinal , Signal Transduction/drug effects , Time FactorsABSTRACT
Endoplasmic reticulum (ER) stress-associated inflammation positively contributes to insulin resistance. It is also known that fucosylated chondroitin sulphate from Cusumaria frondosa (Cf-CHS) can mitigate insulin resistance; however, its effects on ER stress and inflammation are not well understood. Therefore, we investigated whether Cf-CHS-influenced ER stress, inflammatory response and signaling in insulin-resistant mice. Our results showed that Cf-CHS lowered serum and hepatic ROS, NO, and FFA levels. Furthermore, Cf-CHS decreased serum proinflammatory cytokines TNF-α, CRP, MIP-1, IL-1ß and IL-6 concentrations as well as their hepatic mRNA expression, and increased the anti-inflammatory cytokine IL-10 levels. Moreover, Cf-CHS reduced the ER stress markers Bip, ATF6, PERK, and XBP1 mRNA or protein expression, and PERK, eIF2α, and IRE1α phosphorylation. These reductions were accompanied by a reduced activation of JNK1 and IKKß, NFκB nuclear translocation, and IR/IRS-2 serine phosphorylation in Cf-CHS-treated mice. These findings suggested that the Cf-CHS supplementary-induced alleviation of RE stress-associated inflammation could be the mechanism responsible for its beneficial effects against insulin resistance.
Subject(s)
Chondroitin Sulfates/administration & dosage , Diabetes Mellitus, Type 2/drug therapy , Endoplasmic Reticulum Stress/drug effects , Insulin Resistance , Liver/drug effects , Sea Cucumbers/chemistry , Animals , Chondroitin Sulfates/isolation & purification , Diabetes Mellitus, Type 2/genetics , Diabetes Mellitus, Type 2/immunology , Diabetes Mellitus, Type 2/physiopathology , I-kappa B Kinase/genetics , I-kappa B Kinase/immunology , Interleukin-10/genetics , Interleukin-10/immunology , Interleukin-1beta/genetics , Interleukin-1beta/immunology , Interleukin-6/genetics , Interleukin-6/immunology , Liver/immunology , Liver/physiopathology , Male , Mice , Mice, Inbred C57BL , NF-kappa B/genetics , NF-kappa B/immunologyABSTRACT
The aim of this study was to evaluate if the permeability of inhaled corticosteroids entering the brain is reduced and if P-glycoprotein (P-gp) transporters are involved. Currently employed inhaled corticosteroids were given intravenously and intratracheally to rats at a dose of 100 microg kg-1. An ex-vivo receptor binding assay was used to monitor over 12 h the glucocorticoid receptor occupancy in the brain and a systemic reference organ (kidney). The involvement of P-gp in the brain permeability of triamcinolone acetonide was assessed in wild-type mice and mdr1a(-/-) knockout mice (mice lacking the gene for expressing P-gp). After both forms of administration, the average brain receptor occupancies were 20-56% of those of the reference organ, with the more lipophilic drugs showing a more pronounced receptor occupation. While the receptor occupancies in the liver of wild-type and mdr1a(-/-) mice were similar after administration of triamcinolone acetonide, brain receptor occupancies in mdr1a(-/-) mice were significantly greater (mdr1a(-/-): 47.6%, 40.2-55.0%, n=14; 2; wild-type: 11.5+/-33.0%, n=14; 3). Penetration into the brain for inhaled corticosteroids (especially those of lower lipophilicity) is reduced. Experiments in mdr1a(-/-) mice confirmed the involvement of P-gp transporters. Further studies are needed to assess whether potential drug interactions at the transporter level are of pharmacological significance.