Publications by authors named "Kenneth L Audus"

40 Publications

Editorial: Professor Jennifer Dressman.

Authors:
Kenneth L Audus

J Pharm Sci 2021 03 24;110(3):985-986. Epub 2020 Dec 24.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.xphs.2020.12.025DOI Listing
March 2021

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2021 01 10;110(1). Epub 2020 Nov 10.

The University of Kansas, Pharmaceutical Chemistry, Lawrence, KS, USA. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.xphs.2020.11.003DOI Listing
January 2021

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2021 02 29;110(2):554. Epub 2020 Sep 29.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.xphs.2020.09.040DOI Listing
February 2021

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2020 12 28;109(12):3513. Epub 2020 Sep 28.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.xphs.2020.09.036DOI Listing
December 2020

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2020 11 18;109(11):3233-3234. Epub 2020 Sep 18.

Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas, USA. Electronic address:

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.xphs.2020.09.018DOI Listing
November 2020

Placental ABC Transporters: Biological Impact and Pharmaceutical Significance.

Pharm Res 2016 12 19;33(12):2847-2878. Epub 2016 Sep 19.

Department of Pharmaceutics, Virginia Commonwealth University School of Pharmacy, Richmond, Virginia, 23298-0533, USA.

The human placenta fulfills a variety of essential functions during prenatal life. Several ABC transporters are expressed in the human placenta, where they play a role in the transport of endogenous compounds and may protect the fetus from exogenous compounds such as therapeutic agents, drugs of abuse, and other xenobiotics. To date, considerable progress has been made toward understanding ABC transporters in the placenta. Recent studies on the expression and functional activities are discussed. This review discusses the placental expression and functional roles of several members of ABC transporter subfamilies B, C, and G including MDR1/P-glycoprotein, the MRPs, and BCRP, respectively. Since placental ABC transporters modulate fetal exposure to various compounds, an understanding of their functional and regulatory mechanisms will lead to more optimal medication use when necessary in pregnancy.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11095-016-2028-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5384842PMC
December 2016

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2016 Feb;105(2):369

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/S0022-3549(15)00179-3DOI Listing
February 2016

Editorial.

Authors:
Kenneth L Audus

J Pharm Sci 2015 Feb 15;104(2):288-9. Epub 2015 Jan 15.

Journal of Pharmaceutical Sciences.

View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jps.24349DOI Listing
February 2015

The permeation of dynorphin A 1-6 across the blood brain barrier and its effect on bovine brain microvessel endothelial cell monolayer permeability.

Peptides 2012 Dec 6;38(2):414-7. Epub 2012 Oct 6.

Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66047, USA.

Dynorphin A 1-17 (Dyn A 1-17) is an endogenous neuropeptide known to act at the kappa opioid receptor; it has been implicated in a number of neurological disorders, including neuropathic pain, stress, depression, and Alzheimer's and Parkinson's diseases. The investigation of Dyn A 1-17 metabolism at the blood-brain barrier (BBB) is important since the metabolites exhibit unique biological functions compared to the parent compound. In this work, Dyn A 1-6 is identified as a metabolite of Dyn A 1-17 in the presence of bovine brain microvessel endhothelial cells (BBMECs), using LC-MS/MS. The transport of Dyn A 1-6 at the BBB was examined using this in vitro cell culture model of the BBB. Furthermore, the permeation of the BBB by the low molecular weight permeability marker fluorescein was characterized in the presence and absences of Dyn A 1-6.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.peptides.2012.09.031DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3540977PMC
December 2012

Analytical and biological methods for probing the blood-brain barrier.

Annu Rev Anal Chem (Palo Alto Calif) 2012 ;5:505-31

Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas 66047, USA.

The blood-brain barrier (BBB) is an important interface between the peripheral and central nervous systems. It protects the brain against the infiltration of harmful substances and regulates the permeation of beneficial endogenous substances from the blood into the extracellular fluid of the brain. It can also present a major obstacle in the development of drugs that are targeted for the central nervous system. Several methods have been developed to investigate the transport and metabolism of drugs, peptides, and endogenous compounds at the BBB. In vivo methods include intravenous injection, brain perfusion, positron emission tomography, and microdialysis sampling. Researchers have also developed in vitro cell-culture models that can be employed to investigate transport and metabolism at the BBB without the complication of systemic involvement. All these methods require sensitive and selective analytical methods to monitor the transport and metabolism of the compounds of interest at the BBB.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1146/annurev-anchem-062011-143002DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3744104PMC
October 2012

Lipopolysaccharide increases the expression of multidrug resistance-associated protein 1 (MRP1) in RAW 264.7 macrophages.

J Neuroimmune Pharmacol 2010 Dec 6;5(4):516-20. Epub 2009 Nov 6.

Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City, Kansas City, MO 64108, USA.

Multidrug resistance-associated protein 1 (MRP-1) is a ubiquitously expressed member of the ATP-binding cassette transporter family. MRP-1 is one of the primary transporters of glutathione and glutathione conjugates. This protein also transports antiretroviral therapeutics, such as HIV-1 protease inhibitors (PI). We hypothesized that inflammatory mediators that activate macrophages would modify the expression and activity of MRP-1 in macrophages. Real-time PCR assays, western blots, and calcein efflux assays were used to show that exposure of macrophage cell line RAW 264.7 to lipopolysaccharide (LPS) increased expression of MRP-1 at the levels of mRNA, protein, and functional activity. Treatment of macrophages with LPS resulted in 2-fold increases of MRP-1 expression or functional activity. LPS-mediated increases in calcein efflux were repressed by the MRP-specific inhibitor MK-571. These results suggest that the effectiveness of HIV-1 PI therapy may be compromised by the presence of opportunistic infections.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11481-009-9180-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4051155PMC
December 2010

MRP isoforms and BCRP mediate sulfate conjugate efflux out of BeWo cells.

Int J Pharm 2010 Jan 25;384(1-2):15-23. Epub 2009 Sep 25.

Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS 66047, USA.

The breast cancer resistance protein (BCRP) and the multidrug resistance-associated proteins (MRPs) have the ability to eliminate sulfate conjugates but it is not known if this constitutes one of their roles in the placenta. To determine this, the BeWo cell line was used as a model of placental trophoblast cells and the mechanisms of elimination of sulfate metabolites of two common sulfotransferase substrates, 4-nitrophenol and acetaminophen were examined. At 0.5-200 microM, neither 4-nitrophenyl sulfate nor acetaminophen sulfate affected the accumulation of the BCRP substrates BODIPY FL prazosin or mitoxantrone in BeWo monolayers, indicating a lack of interaction of BCRP with the sulfates. Examination of the effect of BCRP/MRP inhibitors on the efflux of intracellularly generated 4-nitrophenyl sulfate and acetaminophen sulfate, indicated that one or more of the MRP isoforms play a major role in the elimination of 4-nitrophenyl sulfate and acetaminophen sulfate across the basolateral (fetal-facing) and apical (maternal-facing) membranes respectively. BCRP played a minor role in the elimination of these two sulfate conjugates across the apical membrane. This study demonstrates that a yet undetermined role of trophoblast efflux transporters is the elimination of sulfate conjugates.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ijpharm.2009.09.033DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2790001PMC
January 2010

(3R,5S,7as)-(3,5-Bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol, a novel neuroprotective agent.

J Med Chem 2009 Dec;52(23):7537-43

Department of Pharmaceutical Chemistry, The University of Kansas, 2095 Constant Avenue, Lawrence, Kansas 66047, USA.

Compounds that interact with microtubules, such as paclitaxel, have been shown to possess protective properties against beta-amyloid (Abeta) induced neurodegeneration associated with Alzheimer's disease. In this work, the novel agent (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol was investigated for effectiveness in protecting neurons against several toxic stimuli and its interaction with the microtubule network. Exposure of neuronal cultures to Abeta peptide in the presence of 5 nM (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol resulted in a 50% increase in survival. Neuronal cultures treated with other toxic stimuli such as staurosporine, thapsigargin, paraquat, and H(2)O(2) showed significantly enhanced survival in the presence of (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol. Microtubule binding and tubulin assembly studies revealed differences compared to paclitaxel but confirmed the interaction of (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol with microtubules. Furthermore, in vitro studies using bovine brain microvessel endothelial cells experiments suggest that (3R,5S,7as)-(3,5-bis(4-fluorophenyl)tetrahydro-1H-oxazolo[3,4-c]oxazol-7a-yl)methanol can readily cross the blood-brain barrier in a passive manner.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jm900254kDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2788673PMC
December 2009

TCP-FA4: a derivative of tranylcypromine showing improved blood-brain permeability.

Biochem Pharmacol 2009 Dec 11;78(11):1412-7. Epub 2009 Aug 11.

The University of Kansas, Department of Pharmaceutical Chemistry, 2095 Constant Ave, Lawrence, KS 66047, USA.

A variety of approaches have been taken to improve the brain penetration of pharmaceutical agents. The amphipathic character of a compound can improve its interaction with the lipid bilayer within cell membranes, and as a result improve permeability. Fatty acid chains or lipoamino acids of various lengths were attached to tranylcypromine (TCP), in an attempt to improve the blood-brain barrier (BBB) permeability by increasing the lipophilicity as well as the amphiphatic character of the drug. TCP-FA4, one of the derivatives containing a four carbon alkyl acid chain, showed the greatest improvement in permeability. This molecule was slightly neuroprotective in a beta-amyloid-induced neurodegeneration assay and may also be capable of upregulating brain derived neurotrophic factor (BDNF), as indicated by cell culture assays using human umbilical vein endothelial cells. Since decreased levels of BDNF are observed in many CNS disorders, and direct injection of BDNF is not a viable option due to its poor permeability across the BBB, small molecules capable of regulating BDNF that also cross the BBB may be an interesting treatment option.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bcp.2009.07.027DOI Listing
December 2009

Expression and functional activities of selected sulfotransferase isoforms in BeWo cells and primary cytotrophoblast cells.

Biochem Pharmacol 2009 Dec 30;78(12):1475-82. Epub 2009 Jul 30.

Department of Pharmaceutical Chemistry, School of Pharmacy, University of Kansas, Lawrence, KS 66047, USA.

Several cytosolic sulfotransferase enzyme isoforms are functional in placenta but there is limited information available on the utility of cultured trophoblast cells for studying sulfation. The trophoblast cell layer constitutes the rate-determining barrier for trans-placental transfer. The objective of this work was to examine the mRNA expression and enzyme activities of four sulfotransferase isoforms reported to be functional in human placenta (SULT1A1, SULT1A3, SULT1E1, and SULT2A1) in primary cytotrophoblast cells and the trophoblast-like BeWo cell line. Reverse transcription polymerase chain reaction (RT-PCR) was performed to determine mRNA expression. Enzyme activities were assessed using the following substrates: 4-nitrophenol for SULT1A1, dopamine for SULT1A3, 17beta-estradiol for SULT1E1, and dehydroepiandrosterone for SULT2A1. For 4-nitrophenol and dopamine sulfation, apparent K(m) values, response to inhibitors (2,6-dichloro-4-nitrophenol and sodium chloride), and thermal stability profiles indicated that 4-nitrophenol and dopamine sulfation in BeWo cells were being mediated by SULT1A1 and SULT1A3, respectively. SULT1A1 and SULT1A3 were also functional in the cytotrophoblast cells. Both at the protein and at the mRNA levels, SULT1A1 was more abundant in BeWo cells in comparison to the primary cytotrophoblast cells. SULT1E1 and SULT2A1 mRNA were not detected in the cytotrophoblasts. SULT1E1 mRNA was weakly expressed in BeWo but there was negligible functional activity. Although SULT2A1 mRNA was abundantly expressed in BeWo, Western blot and enzyme activities revealed that the protein is not expressed in BeWo cells. The results suggest that the BeWo cells and the cytotrophoblast cells can be used to examine the roles of SULT1A1 and SULT1A3 in placental metabolism.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bcp.2009.07.013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2767256PMC
December 2009

Paclitaxel succinate analogs: Anionic and amide introduction as a strategy to impart blood-brain barrier permeability.

Bioorg Med Chem Lett 2008 Nov 2;18(22):5971-4. Epub 2008 Oct 2.

Department of Medicinal Chemistry, University of Kansas, Malott Hall 4070, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.

A focused library of TX-67 (C10 hemi-succinate) analogs has been prepared, including C7 regioisomers, esters, amides, and one-carbon homologs. These were prepared to investigate whether the lack of TX-67 interaction with P-glycoprotein (Pgp) is due to the presence of the carboxylic acid moiety and whether this phenomenon was restricted to C10 analogs. Tubulin stabilization ability, cytotoxicity, and Pgp interactions were evaluated. All carboxylic acid analogs and several of the amides had no apparent interactions with Pgp at the concentrations used, whereas the ester variants displayed characteristics of Pgp substrates. Furthermore, it was demonstrated that hydrogen-bonding properties were significant with respect to Pgp interactions. Calculations of logD and cross-sectional areas revealed that these analogs are predicted to partition into the membrane and can compete for Pgp binding sites. The anionic and amide introduction strategy may allow for delivery of paclitaxel into the CNS and may be a potential approach for the delivery of other, structurally complex and lipophilic non-CNS permeable drugs.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmcl.2008.09.103DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2634772PMC
November 2008

Contributions of phosphorylation to regulation of OCTN2 uptake of carnitine are minimal in BeWo cells.

Biochem Pharmacol 2008 Feb 19;75(3):745-51. Epub 2007 Sep 19.

Department of Pharmaceutical Chemistry, School of Pharmacy, The University of Kansas, Lawrence, KS 66047, USA.

Physiological functions of organic cation transporters (OCTs) in the placenta include transporting essential nutrients from the maternal to fetal circulations. OCTN2 transports carnitine with high affinity, and the transport of several drugs has also been shown to be mediated by this transporter. In this work, the role of phosphorylation and dephosphorylation mechanisms in regulating OCTN2 was investigated by observing the effects of various activators and inhibitors of kinases and phosphatases on the uptake of carnitine in BeWo cells, a human choriocarcinoma trophoblast cell line frequently used as an in vitro model of the rate-limiting barrier for maternal-fetal exchange. Preincubation with genistein resulted in significant increases in both alkaline phosphatase (ALP) activity and carnitine uptake. Levamisole, an ALP inhibitor, caused a more substantial decrease in carnitine uptake than expected from its corresponding decrease in ALP activity. It was determined that levamisole competitively inhibits carnitine uptake, with a K(i) value of 1.01+/-0.05mM, and this effect has a greater role in decreasing carnitine uptake than any indirect effects of ALP inhibition upon OCTN2 function. Progesterone also competitively inhibited carnitine uptake (K(i)=48.6+/-5.0muM), but had no effect on ALP activity in BeWo cells.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bcp.2007.09.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2254759PMC
February 2008

Effects of low oxygen levels on the expression and function of transporter OCTN2 in BeWo cells.

J Pharm Pharmacol 2007 Aug;59(8):1095-102

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA.

Although hypoxia is normal in early pregnancy, low placental oxygen concentrations later in pregnancy are often linked to complications such as pre-eclampsia and intrauterine growth restriction. The effects of low oxygen levels on drug and nutrient uptake via the organic cation transporter OCTN2 has been studied in BeWo cells, an in-vitro model of human trophoblast. BeWo cells were cultured under 20% (control) or 2% O(2) (hypoxia) for 48 h before each experiment. In-vitro hypoxia was also simulated by the addition of CoCl(2) to the cell culture medium. RT-PCR indicated increased transcription of OCTN2 in BeWo cells cultured under hypoxia, but Western blots did not show a corresponding increase in the amount of OCTN2 protein in the hypoxic cells compared with control. Hypoxia resulted in significant reductions in OCTN2-mediated carnitine uptake. Decreased placental transport of carnitine may lead to symptoms of carnitine deficiency in infants from hypoxic pregnancies, whether caused by high altitude, pre-eclampsia or other factors. The OCTN1 substrate ergothioneine reversed the effects of hypoxia on carnitine transport, but identical concentrations of N-acetylcysteine, another water-soluble intracellular antioxidant, did not have the same effect.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1211/jpp.59.8.0006DOI Listing
August 2007

Sequence recognition of alpha-LFA-1-derived peptides by ICAM-1 cell receptors: inhibitors of T-cell adhesion.

Chem Biol Drug Des 2007 Sep;70(3):237-46

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS 66047, USA.

Blocking the T-cell adhesion signal from intercellular adhesion molecule-1/leukocyte function-associated antigen-1 interactions (Signal-2) can suppress the progression of autoimmune diseases (i.e. type-1 diabetes, psoriasis) and prevent allograph rejection. In this study, we determined the active region(s) of cLAB.L peptide [cyclo(1,12)Pen-ITDGEATDSGC] by synthesizing and evaluating the biologic activity of hexapeptides in inhibiting T-cell adhesion. A new heterotypic T-cell adhesion assay was also developed to provide a model for the T-cell adhesion process during lung inflammation. Two hexapeptides, ITDGEA and DGEATD, were found to be more active than the other linear hexapeptides. The cyclic derivative of ITDGEA [i.e. cyclo(1,6)ITDGEA] has similar activity than the parent linear peptide and has lower activity than cLAB.L peptide. Computational-binding experiments were carried out to explain the possible mechanism of binding of these peptides to intercellular adhesion molecule-1. Both ITDGEA and DGEATD bind the same site on intercellular adhesion molecule-1 and they interact with the Gln34 and Gln73 residues on D1 of intercellular adhesion molecule-1. In the future, more potent derivatives of cyclo(1,6)ITDGEA will be designed by utilizing structural and binding studies of the peptide to intercellular adhesion molecule-1. The heterotypic T-cell adhesion to Calu-3 will also be used as another assay to evaluate the selectivity of the designed peptides.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1111/j.1747-0285.2007.00549.xDOI Listing
September 2007

Low-affinity uptake of the fluorescent organic cation 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (4-Di-1-ASP) in BeWo cells.

Biochem Pharmacol 2007 Mar 1;73(6):891-900. Epub 2006 Dec 1.

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS 66047, United States.

Understanding the mechanisms of transport processes in the placenta can improve the safety and efficacy of drug delivery during pregnancy. Functional studies of organic cation transporters (OCTs) are usually carried out using radioactivity, and a fluorescent marker would add flexibility to experimental methods. As a published substrate for OCT1 and OCT2, the fluorescent compound 4-(4-(dimethylamino)styryl)-N-methylpyridinium iodide (4-Di-1-ASP) was chosen as a candidate for studying placental OCT function in BeWo cells. The expression of OCT1 and OCT2 was also investigated in BeWo cells, an established human choriocarcinoma trophoblastic cell line frequently used as an in vitro model of the rate-limiting barrier for maternal-fetal exchange of drugs and nutrients within the placenta. 4-Di-1-ASP was taken up into BeWo cells by a low-affinity, carrier-mediated process exhibiting a Km of 580+/-110 microM and Vmax of 97+/-9 nmol/mg protein/30 min, and asymmetric transport was observed, with greater permeability in the apical to basolateral (maternal-to-fetal) direction. However, RT-PCR revealed no expression of OCT1 or OCT2 in either BeWo cells or primary cultured human cytotrophoblast cells, and OCT substrates such as TEA and choline did not inhibit the uptake of 4-Di-1-ASP. Although the uptake of this fluorescent compound in BeWo cells is not mediated by an OCT, the colocalization experiments with fluorescence microscopy and inhibition studies confirmed significant mitochondrial uptake of 4-Di-1-ASP. Transport of 4-Di-1-ASP into the nuclear region of BeWo cells was also observed, which is likely mediated by a nucleoside transporter.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bcp.2006.11.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1941684PMC
March 2007

Investigation of the metabolism of substance P at the blood-brain barrier using LC-MS/MS.

J Pharm Biomed Anal 2007 Mar 21;43(4):1409-15. Epub 2006 Nov 21.

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, KS 66047, USA.

Substance P (SP) has been associated with pain and depression as well as neurodegenerative diseases. Many of these diverse actions of SP can potentially be attributed to SP metabolites generated at the blood-brain barrier (BBB). In this study, the metabolism of SP was investigated using an in vitro model of the BBB and LC-MS/MS. Substance P metabolism was found to be non-saturable in the concentration range of 100 nM to 10 microM, with approximately 70% of the peptide remaining intact after 5 h. The major metabolites of SP were identified by MS as 3-11 and 5-11. Two previously unreported metabolites, 5-11 and 6-11, were also found in our studies. Several additional minor SP metabolites, including 1-9 and 2-11, were also identified. A profile of the SP metabolites generated by the BBB over time was obtained. The results from the present study provide a better understanding of the role of the blood-brain barrier in the pharmacology of SP.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.jpba.2006.10.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1945052PMC
March 2007

Characteristics of substance P transport across the blood-brain barrier.

Pharm Res 2006 Jun 1;23(6):1201-8. Epub 2006 Jun 1.

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas 66047, USA.

Purpose: Substance P (SP; NH3(+)-Arg(+)-Pro-Lys(+)-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2) belongs to a group of neurokinins that are widely distributed in the central nervous system and peripheral nervous system. The biological effects mediated by SP in the central nervous system include regulation of affective behavior, emesis, and nociception. Many of these actions are believed to be the result of the binding of SP to the neurokinin-1 (NK-1) receptor and subsequent transport across the blood-brain barrier (BBB). The objective of the study was to investigate the involvement of the NK-1 receptor in the permeation of SP across the BBB.

Methods: Transport of 3H SP (1-13 nM) was investigated using BBMEC monolayers grown on polycarbonate membranes mounted on a Side-bi-Side diffusion apparatus. 3H SP samples were analyzed by scintillation spectrometry. Liquid chromatography-tandem mass spectrometry was used to monitor the transport at higher concentrations (micromolar).

Results: SP transport across BBMEC monolayers was found to be saturable (Km = 8.57 +/- 1.59 nM, Vmax = 0.017 +/- 0.005 pmol min(-1) mg(-1) protein) in the concentration range of 0-13 nM. Significant (p < 0.05) decline in 3H SP permeation was observed in the presence of unlabeled SP and at 4 degrees C, indicating that the transport process is carrier-mediated. High-performance liquid chromatography analysis showed no significant metabolism of 3H SP in either the donor or receiver chambers. 3H SP transport was inhibited by 2-11 SP (p < 0.05) but not by any other fragments, indicating that both the C- and N-terminal regions are essential for molecular recognition by the receptor. Endocytic inhibitors (chloroquine, phenylarsine oxide, monensin, and brefeldin) did not inhibit SP transport, suggesting the involvement of a nonendocytic mechanism in SP permeation. Pro(9) SP, a high-affinity substrate for the NK-1 major subtype receptor, significantly (p < 0.05) inhibited the transport of SP. However, Sar(9)Met(O2)(11) SP, a high-affinity substrate for the NK-1 minor subtype receptor, septide, and neurokinin A, inhibitors of NK-1 and neurokinin-2 (NK-2) receptors, respectively, did not produce any inhibition of SP transport. Western blot analysis confirmed the presence of the NK-1 receptor in BBMEC monolayers.

Conclusions: The above results provide functional and molecular evidence for the existence of a carrier-mediated mechanism in the transport of SP across the BBB. The effects of specific inhibitors and the results of Western blot analyses demonstrate the involvement of the NK-1 receptor in the transport of SP across the BBB.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1007/s11095-006-0068-1DOI Listing
June 2006

In vitro models for studying trophoblast transcellular transport.

Methods Mol Med 2006 ;122:225-39

Department of Pharmaceutical Chemistry, School of Pharmacy, University of Kansas, Lawrence, USA.

In vitro models have proven to be effective in studying the placental transporters that play a role in the exchange of nutrients, waste products, and drugs between the maternal and fetal circulations. Although primary cultures of trophoblast cells can be used to perform uptake, efflux, and metabolism studies, only the rodent HRP-1 and the human BeWo cell lines have been shown to form confluent monolayers when grown on semi-permeable membranes. Protocols for the revival, maintenance, passage, and growth of BeWo cells for transporter expression and transcellular transport studies are provided.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2265081PMC
http://dx.doi.org/10.1385/1-59259-989-3:225DOI Listing
April 2006

Tetrazole compounds: the effect of structure and pH on Caco-2 cell permeability.

J Pharm Sci 2006 Apr;95(4):717-25

Department of Pharmaceutical Chemistry, The University of Kansas, Lawrence, Kansas, USA.

A tetrazole ring is often used in drug discovery as a replacement for the carboxylic acid group. Previous work indicates that compounds containing a tetrazole moiety show asymmetric permeability in Caco-2 cells characteristic of an efflux transporter substrate. The aim of this study is to determine which transporters are responsible for polarization of transport of tetrazole-containing compounds in Caco-2 cells. Results indicate that only select compounds with tetrazole moieties display asymmetric transport. Three compounds (two commercial drug products and one druglike structure) were selected for further studies. Losartan appears to be primarily a P-glycoprotein (P-gp) substrate, as previously reported, but MRP inhibitors such as MK-571 and rifampicin also affect the difference between apical to basolateral and basolateral to apical transport. Pemirolast and phenyltetrazole derivative C are sensitive to P-gp inhibition, but transport seems to be mediated by one or more of the MRP family of transporters. Additionally, lowering the pH from 7.4 to 4.0 eliminates the polarization of permeability in Caco-2 cells. These studies indicate that some tetrazole compounds are susceptible to efflux, therefore caution should be used when choosing an appropriate functional group to replace carboxylic acids when synthesizing a drug candidate.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1002/jps.20526DOI Listing
April 2006

Single-site chemical modification at C10 of the baccatin III core of paclitaxel and Taxol C reduces P-glycoprotein interactions in bovine brain microvessel endothelial cells.

Bioorg Med Chem Lett 2006 Feb 10;16(3):495-8. Epub 2005 Nov 10.

Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045, USA.

A single-site modification of paclitaxel analogs at the C10 position on the baccatin III core that reduces interaction with P-glycoprotein in bovine brain microvessel endothelial cells is described. Modification and derivatization of the C10 position were carried out using a substrate controlled hydride addition to a key C9 and C10 diketone intermediate. The analogs were tested for tubulin assembly and cytotoxicity, and were shown to retain potency similar to paclitaxel. P-glycoprotein interaction was examined using a rhodamine assay and it was found that simple hydrolysis or epimerization of the C10 acetate of paclitaxel and Taxol C can reduce interaction with the P-glycoprotein transporter that may allow for increased permeation of taxanes into the brain.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmcl.2005.10.063DOI Listing
February 2006

Synthesis and interactions of 7-deoxy-, 10-deacetoxy, and 10-deacetoxy-7-deoxypaclitaxel with NCI/ADR-RES cancer cells and bovine brain microvessel endothelial cells.

Bioorg Med Chem Lett 2006 Jan 3;16(2):433-6. Epub 2005 Nov 3.

Department of Medicinal Chemistry, University of Kansas, 1251 Wescoe Hall Drive, Lawrence, KS 66045-7582, USA.

7-Deoxypaclitaxel, 10-deacetoxypaclitaxel and 10-deacetoxy-7-deoxypaclitaxel were prepared and evaluated for their ability to promote assembly of tubulin into microtubules, their cytotoxicity against NCI/ADR-RES cells and for their interactions with P-glycoprotein in bovine brain microvessel endothelial cells. The three compounds were essentially equivalent to paclitaxel in cytotoxicity against NCI/ADR-RES cells. They also appeared to interact with P-glycoprotein in the endothelial cells with the two 10-deacetoxy compounds having less interaction than paclitaxel and 7-deoxypaclitaxel.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.bmcl.2005.09.043DOI Listing
January 2006

Chemical modification of paclitaxel (Taxol) reduces P-glycoprotein interactions and increases permeation across the blood-brain barrier in vitro and in situ.

J Med Chem 2005 Feb;48(3):832-8

Department of Pharmaceutical Chemistry, University of Kansas, 226 Simons, 2095 Constant Avenue, Lawrence, Kansas 66047, USA.

The purpose of this work was to introduce a chemical modification into the paclitaxel (Taxol) structure to reduce interactions with the product of the multidrug resistant type 1 (MDR1) gene, P-glycoprotein (Pgp), resulting in improved blood-brain barrier (BBB) permeability. Specifically, a taxane analogue, Tx-67, with a succinate group added at the C10 position of Taxol, was synthesized and identified as such a candidate. In comparison studies, Tx-67 had no apparent interactions with Pgp, as demonstrated by the lack of enhanced uptake of rhodamine 123 by brain microvessel endothelial cells (BMECs) in the presence of the agent. By contrast, Taxol exposure substantially enhanced rhodamine 123 uptake by BMECs through inhibition of Pgp. The transport across BMEC monolayers was polarized for both Tx-67 and Taxol with permeation in the apical to basolateral direction greater for Tx-67 and substantially reduced for Taxol relative to basolateral to apical permeation. Taxol and cyclosporin A treatments also did not enhance Tx-67 permeation across BMEC monolayers. In an in situ rat brain perfusion study, Tx-67 was demonstrated to permeate across the BBB at a greater rate than Taxol. These results demonstrate that the Taxol analogue Tx-67 had a reduced interaction with Pgp and, as a consequence, enhanced permeation across the blood-brain barrier in vitro and in situ.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1021/jm040114bDOI Listing
February 2005

National Institute on Drug Abuse Conference report on placental proteins, drug transport, and fetal development.

Am J Obstet Gynecol 2004 Dec;191(6):1858-62

Division of Neuroscience and Behavioral Research. National Institute on Drug Abuse (NIDA), National Institutes of Health, 6001 Executive Boulevard, Room 4282, MSC 9555, Bethesda, MD 20892-9555, USA.

The use of illicit and licit drugs during pregnancy is a major public health concern because of potential adverse effects on the fetus and the risk to maternal health. Because the placenta is the primary link between the mother and the conceptus and is essential for the growth and survival of the fetus, abnormalities in placental formation and function resulting from drug use could have a major influence on pregnancy outcome. At present, little information is available on the impact of abused drugs on placental biology alone or in combination with other "host" factors (eg, stress, infections). This prompted the National Institute on Drug Abuse (NIDA) to convene a meeting of experts in placental biology to review cutting-edge research with the mission to translate existing information to new clinical and research initiatives in the drug abuse field. This report summarizes the presentations and research recommendations resulting from the workshop discussions.
View Article and Find Full Text PDF

Download full-text PDF

Source
http://dx.doi.org/10.1016/j.ajog.2004.07.059DOI Listing
December 2004
-->