Ulrich Bickel - Academia.edu (original) (raw)

Papers by Ulrich Bickel

Pharmaceutical Research, 2002

To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, ... more To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, copolymers and physicochemical properties as well as in vivo behavior of their complexes with NF-〉 decoy. Methods. A variety of copolymers of PEG grafted onto PEI as well as PEI grafted onto PEG were synthesized and their complexes with a double stranded 20mer oligonucleotide were examined regarding size, surface charge, biodistribution and pharmacokinetics. Results. Polyplexes of copolymers were smaller compared to polyplexes formed by non-PEGylated PEI 25 kDa (58 -334 nm vs. 437 nm for a nitrogen/phosphate ratio of 3.5 and 85 -308 nm vs. 408 nm for N/P 6.0) and showed reduced zeta potential (−2.5 -6.4 mV vs. 14.5 mV for N/P 6.0). IV injection into mice revealed liver (35-76 % of injected dose), kidney (3 -22 %) and spleen (2 -16 %) to be the main target organs for all injected complexes. Complexes formed by copolymers with few PEG blocks of higher molecular weight (5 kDa and 20 kDa) grafted onto PEI 25 kDa did not show different blood levels from PEI 25 kDa. In contrast, a copolymer with more short PEG blocks (550 Da) grafted onto PEI showed elevated blood levels with an increase in AUC of 62 %.

Drug Metabolism and Disposition the Biological Fate of Chemicals, Jun 1, 1997

The blood-brain barrier (BBB) permeability to morphine and morphine-6-glucuronide (M6G) is measur... more The blood-brain barrier (BBB) permeability to morphine and morphine-6-glucuronide (M6G) is measured under identical conditions using an intravenous injection method in the rat and HPLC separation of morphine from its metabolites. The brain uptake of M6G expressed as %ID/g was 32-fold lower than that of morphine, and the BBB permeability surface area product (PS) of M6G was 57-fold lower as compared with that of morphine. Consistent with these in vivo data, the 1-octanol/buffer partition study showed the liposolu-bility of M6G was 187-fold lower than that of morphine. The CNS origin of M6G analgesia after peripheral administration was confirmed because the analgesia was completely blocked by naloxone, which crosses BBB, but not by naloxone methiodide, which does not enter brain from blood. In conclusion, the BBB permeability to M6G is markedly reduced as compared with morphine, consistent with the much lower lipid solubility of M6G relative to morphine.

Journal of Cellular Physiology, Nov 1, 2010

Organ-specific vascular targeting, for example to the blood-brain barrier, requires the identific... more Organ-specific vascular targeting, for example to the blood-brain barrier, requires the identification of unique molecular addresses on a subset of endothelial cells. The present study describes a crucial step towards tapping the exquisite specificity of the peptide/HLA class I system for this goal. We utilized a novel T-cell receptor (TCR) mimic antibody of high affinity and specificity, which is restricted by HLA-A2 and has been generated to recognize a peptide epitope derived from p68 RNA helicase (YLLPAIVHI). The parent protein is highly expressed by brain endothelial cells. Flow cytometry and confocal imaging showed that the antibody binds to HLA-A2 positive human brain derived endothelial cells, both immortalized hCMEC/D3 cells and primary cells. The TCR mimic antibody undergoes internalization into vesicles, where significant colocalization occurs with the early endosomal marker EEA-1, but barely with caveolin-1. To our knowledge internalization of neither MHC class I protein nor TCR mimics by brain endothelial cells has been previously observed. Knockdown of p68 protein expression by siRNA reduced the presentation of YLLPAIVHI-peptide/HLA-A2 complexes on the cell membrane by half as measured by flow cytometry 48h later. We also found that brain endothelial cells isolated from HLA-A2 transgenic mouse strains express the A2 transgene, and brain endothelial cells of one of these strains also present YLLPAIVHI-peptide/HLA-A2, making these mouse strains suitable models for studying TCR mimic antibodies in vivo. In conclusion, these data strongly support the notion that TCR mimic antibodies could be a new class of therapeutic targeting agents in a wide variety of diseases.

Drug Metabolism and Disposition

Th. delivery of blotinylated therap.utlcs through the blood-brain barrier (BBB) may b facilitated... more Th. delivery of blotinylated therap.utlcs through the blood-brain barrier (BBB) may b facilitated by the usa of avidin-based chimeric peptide conjugates. The latter are formed by conjugating avidIn to a BBB drug delivery vector, which is a protein that undergoes receptor-

Drug Metabolism and Disposition

The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor ... more The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor B decoy oligodeoxynucleotide (ODN) complexed with 25-kDa poly(ethylene imine) (PEI), low molecular weight 2.7-kDa PEI, and PEGylated PEI [bPEI(25k)-g-lPEG(550) 50 ] after intravenous injection were studied in BALB/c mice using a double-labeling technique to follow simultaneously the distribution of both complex components. The polymers were radioactively labeled with 125 I by Bolton-Hunter reagent and the decoys with [␥-32 P]ATP by an enzymatic 5-end-labeling technique. After i.v. bolus injections into the jugular vein, organ samples were taken after 15 min, 2 h and 12 h. For pharmacokinetic studies blood and plasma samples were collected from 20 s up to 2 h. Uncomplexed decoy was found to be degraded already after 15 min and was rapidly eliminated renally into urine. Complexation with the homopolymers increased the organ levels and circulation time of ODN after 15 min, with similar organ distribution profiles for 125 I and 32 P. In contrast to the behavior of free ODN, the complexes were mainly distributed into liver and spleen. Whereas the organ concentrations of 125 I remained high over 12 h, the 32 P values of ODN decreased in a time-dependent manner, likely due to separation of the complexes and degradation of the DNA. Although PEGylated PEI demonstrated a slower 125 I-uptake into the RES organs compared with 25-kDa PEI due to the shielding effect of PEG [poly(ethylene glycol)], it was not able to better stabilize the complexes in the circulation or protect DNA from degradation. ABBREVIATIONS: PEI, poly(ethylene imine); AUC, area under the curve; LMW, low molecular weight; NF-B nuclear factor B; ODN, oligodeoxynucleotide; PEG, poly(ethylene glycol); T4 PNK, T4 polynucleotide kinase; TCA, trichloroacetic acid; PEI(PEG) 50 , bPEI(25k)-g-lPEG(550) 50 ; N/P ratio, total nitrogen of the polymer per DNA phosphate ratio; %ID, percentage of injected dose; ANOVA, analysis of variance; RES, reticuloendothelial system.

Clinical Pharmacology & Therapeutics, the most cited journal publishing primary investigation... more Clinical Pharmacology & Therapeutics, the most cited journal publishing primary investigation in pharmacology and pharmacy, is the authoritative, cross-disciplinary journal in experimental and clinical medicine devoted to publishing advances in the nature, action, efficacy and evaluation ...

Brain Research, 2015

Liver diseases are known to affect the function of remote organs. The aim of the present study wa... more Liver diseases are known to affect the function of remote organs. The aim of the present study was to investigate the effects of Pringle maneuver, which results in hepatic ischemia-reperfusion (IR) injury, and partial hepatectomy (Hx) on the pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a widely used marker of blood-brain barrier (BBB) permeability. Rats were subjected to Pringle maneuver (total hepatic ischemia) for 20min with (HxIR) or without (IR) 70% hepatectomy. Sham-operated animals underwent laparotomy only. After 15min or 8h of reperfusion, a single 25-mg/kg dose of FL was injected intravenously and serial (0-30min) blood and bile and terminal brain samples were collected. Total and free (ultrafiltration) plasma, total brain homogenate, and bile concentrations of FL and/or its glucuronidated metabolite (FL-Glu) were determined by HPLC. Both IR and HxIR caused significant reductions in the biliary excretions of FL and FL-Glu, resulting in significant increases in the plasma AUC of the marker. Additionally, the free fraction of FL in plasma was significantly increased by HxIR. Although the brain concentrations of FL were increased by almost twofold in both IR and HxIR animals, the brain concentrations corrected by the free FL AUC (and not the total AUC) were similar in both groups at either time points. It is concluded that Pringle maneuver and/or partial hepatectomy substantially alters the hepatobiliary disposition, plasma AUC, plasma free fraction, and brain accumulation of FL without altering the BBB permeability to the marker.

Drug metabolism and disposition: the biological fate of chemicals, 2004

The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor ... more The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor kappaB decoy oligodeoxynucleotide (ODN) complexed with 25-kDa poly(ethylene imine) (PEI), low molecular weight 2.7-kDa PEI, and PEGylated PEI [bPEI(25k)-glPEG(550)(50)] after intravenous injection were studied in BALB/c mice using a double-labeling technique to follow simultaneously the distribution of both complex components. The polymers were radioactively labeled with (125)I by Bolton-Hunter reagent and the decoys with [gamma-(32)P]ATP by an enzymatic 5'-end-labeling technique. After i.v. bolus injections into the jugular vein, organ samples were taken after 15 min, 2 h and 12 h. For pharmacokinetic studies blood and plasma samples were collected from 20 s up to 2 h. Uncomplexed decoy was found to be degraded already after 15 min and was rapidly eliminated renally into urine. Complexation with the homopolymers increased the organ levels and circulation time of ODN after 15 min, wi...

American journal of physiology. Endocrinology and metabolism, 2002

The transport mechanism mediating brain uptake of tumor necrosis factor (TNF)-alpha has been stud... more The transport mechanism mediating brain uptake of tumor necrosis factor (TNF)-alpha has been studied. When (125)I-labeled rat TNF-alpha was used in internal carotid artery perfusions in rats, the cytokine showed transcytosis through the blood-brain barrier in intact form (permeability-surface area product 0.34 +/- 0.13 microl. min(-1). g(-1)). Uptake was inhibited by low nanomolar concentrations of unlabeled rat TNF-alpha. Human TNF-alpha, which does not interact with the p80 TNF receptor in rodents, showed no brain uptake. mRNA expression of both p60 and p80 receptors could be demonstrated in native brain microvessel preparations. These transcripts increased to 149% (p60) and 127% (p80) of control 4 h after a systemic immune stimulation (2 mg/kg bacterial endotoxin ip). Lipopolysaccharide treatment did not alter the rate of brain uptake of TNF-alpha measured between 4 and 24 h later. In conclusion, a receptor-mediated mechanism is responsible for the transcytosis of TNF-alpha. Satu...

International Journal of Oncology, 2008

P-glycoprotein (Pgp), a plasma membrane (PM) glycoprotein, is responsible for the development of ... more P-glycoprotein (Pgp), a plasma membrane (PM) glycoprotein, is responsible for the development of multidrug resistance. The mechanism by which Pgp is targeted to the PM is not defined. To identify proteins that influence Pgp trafficking, we utilized the yeast two-hybrid analysis procedure, which identified a new isoform of endoplasmic reticulum (ER)-bound Bap29, termed Bap29varP, as an interacting protein with the N-terminus of Pgp. The drug-resistant human breast cancer MCF-7 (MCF-7/Adr(R)) cells express both Bap29varP and approximately 170 kDa Pgp, which are however absent in the drug-sensitive MCF-7 cells. When Bap29varP was overexpressed in MCF-7/Adr(R) cells, Pgp was predominantly localized in the ER and intracellular vesicles, suggesting Bap29varP influences Pgp trafficking. When Pgp was expressed in MCF-7 cells, it was exclusively found in the ER with a molecular mass of approximately 160 kDa slightly smaller than that of the molecular mass of Pgp expressed in MCF-7/Adr(R) cells. On the other hand, when Pgp was expressed in Bap29varP-containing human colon adenocarcinoma HT-29 cells, it was localized at the PM. These findings together suggest that Bap29varP acts as an essential chaperone, influencing the processing and trafficking of Pgp to the cell surface.

Pharmaceutical research, 2002

To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, ... more To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, copolymers and physicochemical properties as well as in vivo behavior of their complexes with NF-kappaB decoy. A variety of copolymers of PEG grafted onto PEI as well as PEI grafted onto PEG were synthesized and their complexes with a double stranded 20mer oligonucleotide were examined regarding size, surface charge, biodistribution and pharmacokinetics. Polyplexes of copolymers were smaller compared to polyplexes formed by non-PEGylated PEI 25 kDa (58 - 334 nm vs. 437 nm for a nitrogen/phosphate ratio of 3.5 and 85 - 308 nm vs. 408 nm for N/P 6.0) and showed reduced zeta potential (-2.5 - 6.4 mV vs. 14.5 mV for N/P 6.0). IV injection into mice revealed liver (35-76% of injected dose), kidney (3 - 22%) and spleen (2 - 16%) to be the main target organs for all injected complexes. Complexes formed by copolymers with few PEG blocks of higher molecular weight (5 kDa and 20 kDa) grafted onto ...

Pharmaceutical Research, 2002

To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, ... more To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, copolymers and physicochemical properties as well as in vivo behavior of their complexes with NF-〉 decoy. Methods. A variety of copolymers of PEG grafted onto PEI as well as PEI grafted onto PEG were synthesized and their complexes with a double stranded 20mer oligonucleotide were examined regarding size, surface charge, biodistribution and pharmacokinetics. Results. Polyplexes of copolymers were smaller compared to polyplexes formed by non-PEGylated PEI 25 kDa (58 -334 nm vs. 437 nm for a nitrogen/phosphate ratio of 3.5 and 85 -308 nm vs. 408 nm for N/P 6.0) and showed reduced zeta potential (−2.5 -6.4 mV vs. 14.5 mV for N/P 6.0). IV injection into mice revealed liver (35-76 % of injected dose), kidney (3 -22 %) and spleen (2 -16 %) to be the main target organs for all injected complexes. Complexes formed by copolymers with few PEG blocks of higher molecular weight (5 kDa and 20 kDa) grafted onto PEI 25 kDa did not show different blood levels from PEI 25 kDa. In contrast, a copolymer with more short PEG blocks (550 Da) grafted onto PEI showed elevated blood levels with an increase in AUC of 62 %.

Drug Metabolism and Disposition the Biological Fate of Chemicals, Jun 1, 1997

The blood-brain barrier (BBB) permeability to morphine and morphine-6-glucuronide (M6G) is measur... more The blood-brain barrier (BBB) permeability to morphine and morphine-6-glucuronide (M6G) is measured under identical conditions using an intravenous injection method in the rat and HPLC separation of morphine from its metabolites. The brain uptake of M6G expressed as %ID/g was 32-fold lower than that of morphine, and the BBB permeability surface area product (PS) of M6G was 57-fold lower as compared with that of morphine. Consistent with these in vivo data, the 1-octanol/buffer partition study showed the liposolu-bility of M6G was 187-fold lower than that of morphine. The CNS origin of M6G analgesia after peripheral administration was confirmed because the analgesia was completely blocked by naloxone, which crosses BBB, but not by naloxone methiodide, which does not enter brain from blood. In conclusion, the BBB permeability to M6G is markedly reduced as compared with morphine, consistent with the much lower lipid solubility of M6G relative to morphine.

Journal of Cellular Physiology, Nov 1, 2010

Organ-specific vascular targeting, for example to the blood-brain barrier, requires the identific... more Organ-specific vascular targeting, for example to the blood-brain barrier, requires the identification of unique molecular addresses on a subset of endothelial cells. The present study describes a crucial step towards tapping the exquisite specificity of the peptide/HLA class I system for this goal. We utilized a novel T-cell receptor (TCR) mimic antibody of high affinity and specificity, which is restricted by HLA-A2 and has been generated to recognize a peptide epitope derived from p68 RNA helicase (YLLPAIVHI). The parent protein is highly expressed by brain endothelial cells. Flow cytometry and confocal imaging showed that the antibody binds to HLA-A2 positive human brain derived endothelial cells, both immortalized hCMEC/D3 cells and primary cells. The TCR mimic antibody undergoes internalization into vesicles, where significant colocalization occurs with the early endosomal marker EEA-1, but barely with caveolin-1. To our knowledge internalization of neither MHC class I protein nor TCR mimics by brain endothelial cells has been previously observed. Knockdown of p68 protein expression by siRNA reduced the presentation of YLLPAIVHI-peptide/HLA-A2 complexes on the cell membrane by half as measured by flow cytometry 48h later. We also found that brain endothelial cells isolated from HLA-A2 transgenic mouse strains express the A2 transgene, and brain endothelial cells of one of these strains also present YLLPAIVHI-peptide/HLA-A2, making these mouse strains suitable models for studying TCR mimic antibodies in vivo. In conclusion, these data strongly support the notion that TCR mimic antibodies could be a new class of therapeutic targeting agents in a wide variety of diseases.

Drug Metabolism and Disposition

Th. delivery of blotinylated therap.utlcs through the blood-brain barrier (BBB) may b facilitated... more Th. delivery of blotinylated therap.utlcs through the blood-brain barrier (BBB) may b facilitated by the usa of avidin-based chimeric peptide conjugates. The latter are formed by conjugating avidIn to a BBB drug delivery vector, which is a protein that undergoes receptor-

Drug Metabolism and Disposition

The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor ... more The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor B decoy oligodeoxynucleotide (ODN) complexed with 25-kDa poly(ethylene imine) (PEI), low molecular weight 2.7-kDa PEI, and PEGylated PEI [bPEI(25k)-g-lPEG(550) 50 ] after intravenous injection were studied in BALB/c mice using a double-labeling technique to follow simultaneously the distribution of both complex components. The polymers were radioactively labeled with 125 I by Bolton-Hunter reagent and the decoys with [␥-32 P]ATP by an enzymatic 5-end-labeling technique. After i.v. bolus injections into the jugular vein, organ samples were taken after 15 min, 2 h and 12 h. For pharmacokinetic studies blood and plasma samples were collected from 20 s up to 2 h. Uncomplexed decoy was found to be degraded already after 15 min and was rapidly eliminated renally into urine. Complexation with the homopolymers increased the organ levels and circulation time of ODN after 15 min, with similar organ distribution profiles for 125 I and 32 P. In contrast to the behavior of free ODN, the complexes were mainly distributed into liver and spleen. Whereas the organ concentrations of 125 I remained high over 12 h, the 32 P values of ODN decreased in a time-dependent manner, likely due to separation of the complexes and degradation of the DNA. Although PEGylated PEI demonstrated a slower 125 I-uptake into the RES organs compared with 25-kDa PEI due to the shielding effect of PEG [poly(ethylene glycol)], it was not able to better stabilize the complexes in the circulation or protect DNA from degradation. ABBREVIATIONS: PEI, poly(ethylene imine); AUC, area under the curve; LMW, low molecular weight; NF-B nuclear factor B; ODN, oligodeoxynucleotide; PEG, poly(ethylene glycol); T4 PNK, T4 polynucleotide kinase; TCA, trichloroacetic acid; PEI(PEG) 50 , bPEI(25k)-g-lPEG(550) 50 ; N/P ratio, total nitrogen of the polymer per DNA phosphate ratio; %ID, percentage of injected dose; ANOVA, analysis of variance; RES, reticuloendothelial system.

Clinical Pharmacology & Therapeutics, the most cited journal publishing primary investigation... more Clinical Pharmacology & Therapeutics, the most cited journal publishing primary investigation in pharmacology and pharmacy, is the authoritative, cross-disciplinary journal in experimental and clinical medicine devoted to publishing advances in the nature, action, efficacy and evaluation ...

Brain Research, 2015

Liver diseases are known to affect the function of remote organs. The aim of the present study wa... more Liver diseases are known to affect the function of remote organs. The aim of the present study was to investigate the effects of Pringle maneuver, which results in hepatic ischemia-reperfusion (IR) injury, and partial hepatectomy (Hx) on the pharmacokinetics and brain distribution of sodium fluorescein (FL), which is a widely used marker of blood-brain barrier (BBB) permeability. Rats were subjected to Pringle maneuver (total hepatic ischemia) for 20min with (HxIR) or without (IR) 70% hepatectomy. Sham-operated animals underwent laparotomy only. After 15min or 8h of reperfusion, a single 25-mg/kg dose of FL was injected intravenously and serial (0-30min) blood and bile and terminal brain samples were collected. Total and free (ultrafiltration) plasma, total brain homogenate, and bile concentrations of FL and/or its glucuronidated metabolite (FL-Glu) were determined by HPLC. Both IR and HxIR caused significant reductions in the biliary excretions of FL and FL-Glu, resulting in significant increases in the plasma AUC of the marker. Additionally, the free fraction of FL in plasma was significantly increased by HxIR. Although the brain concentrations of FL were increased by almost twofold in both IR and HxIR animals, the brain concentrations corrected by the free FL AUC (and not the total AUC) were similar in both groups at either time points. It is concluded that Pringle maneuver and/or partial hepatectomy substantially alters the hepatobiliary disposition, plasma AUC, plasma free fraction, and brain accumulation of FL without altering the BBB permeability to the marker.

Drug metabolism and disposition: the biological fate of chemicals, 2004

The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor ... more The in vivo body distribution and the pharmacokinetics of a 20mer double-stranded nuclear factor kappaB decoy oligodeoxynucleotide (ODN) complexed with 25-kDa poly(ethylene imine) (PEI), low molecular weight 2.7-kDa PEI, and PEGylated PEI [bPEI(25k)-glPEG(550)(50)] after intravenous injection were studied in BALB/c mice using a double-labeling technique to follow simultaneously the distribution of both complex components. The polymers were radioactively labeled with (125)I by Bolton-Hunter reagent and the decoys with [gamma-(32)P]ATP by an enzymatic 5'-end-labeling technique. After i.v. bolus injections into the jugular vein, organ samples were taken after 15 min, 2 h and 12 h. For pharmacokinetic studies blood and plasma samples were collected from 20 s up to 2 h. Uncomplexed decoy was found to be degraded already after 15 min and was rapidly eliminated renally into urine. Complexation with the homopolymers increased the organ levels and circulation time of ODN after 15 min, wi...

American journal of physiology. Endocrinology and metabolism, 2002

The transport mechanism mediating brain uptake of tumor necrosis factor (TNF)-alpha has been stud... more The transport mechanism mediating brain uptake of tumor necrosis factor (TNF)-alpha has been studied. When (125)I-labeled rat TNF-alpha was used in internal carotid artery perfusions in rats, the cytokine showed transcytosis through the blood-brain barrier in intact form (permeability-surface area product 0.34 +/- 0.13 microl. min(-1). g(-1)). Uptake was inhibited by low nanomolar concentrations of unlabeled rat TNF-alpha. Human TNF-alpha, which does not interact with the p80 TNF receptor in rodents, showed no brain uptake. mRNA expression of both p60 and p80 receptors could be demonstrated in native brain microvessel preparations. These transcripts increased to 149% (p60) and 127% (p80) of control 4 h after a systemic immune stimulation (2 mg/kg bacterial endotoxin ip). Lipopolysaccharide treatment did not alter the rate of brain uptake of TNF-alpha measured between 4 and 24 h later. In conclusion, a receptor-mediated mechanism is responsible for the transcytosis of TNF-alpha. Satu...

International Journal of Oncology, 2008

P-glycoprotein (Pgp), a plasma membrane (PM) glycoprotein, is responsible for the development of ... more P-glycoprotein (Pgp), a plasma membrane (PM) glycoprotein, is responsible for the development of multidrug resistance. The mechanism by which Pgp is targeted to the PM is not defined. To identify proteins that influence Pgp trafficking, we utilized the yeast two-hybrid analysis procedure, which identified a new isoform of endoplasmic reticulum (ER)-bound Bap29, termed Bap29varP, as an interacting protein with the N-terminus of Pgp. The drug-resistant human breast cancer MCF-7 (MCF-7/Adr(R)) cells express both Bap29varP and approximately 170 kDa Pgp, which are however absent in the drug-sensitive MCF-7 cells. When Bap29varP was overexpressed in MCF-7/Adr(R) cells, Pgp was predominantly localized in the ER and intracellular vesicles, suggesting Bap29varP influences Pgp trafficking. When Pgp was expressed in MCF-7 cells, it was exclusively found in the ER with a molecular mass of approximately 160 kDa slightly smaller than that of the molecular mass of Pgp expressed in MCF-7/Adr(R) cells. On the other hand, when Pgp was expressed in Bap29varP-containing human colon adenocarcinoma HT-29 cells, it was localized at the PM. These findings together suggest that Bap29varP acts as an essential chaperone, influencing the processing and trafficking of Pgp to the cell surface.

Pharmaceutical research, 2002

To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, ... more To study the relationship between structure of poly(ethylene imine-co-ethylene glycol), PEI-PEG, copolymers and physicochemical properties as well as in vivo behavior of their complexes with NF-kappaB decoy. A variety of copolymers of PEG grafted onto PEI as well as PEI grafted onto PEG were synthesized and their complexes with a double stranded 20mer oligonucleotide were examined regarding size, surface charge, biodistribution and pharmacokinetics. Polyplexes of copolymers were smaller compared to polyplexes formed by non-PEGylated PEI 25 kDa (58 - 334 nm vs. 437 nm for a nitrogen/phosphate ratio of 3.5 and 85 - 308 nm vs. 408 nm for N/P 6.0) and showed reduced zeta potential (-2.5 - 6.4 mV vs. 14.5 mV for N/P 6.0). IV injection into mice revealed liver (35-76% of injected dose), kidney (3 - 22%) and spleen (2 - 16%) to be the main target organs for all injected complexes. Complexes formed by copolymers with few PEG blocks of higher molecular weight (5 kDa and 20 kDa) grafted onto ...