Marjo Yliperttula | University of Helsinki (original) (raw)

Papers by Marjo Yliperttula

Journal of pharmaceutical sciences, 2005

Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequival... more Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequivalence testing for the approval of immediate release (IR) solid oral dosage forms containing ranitidine hydrochloride are reviewed. According to the current Biopharmaceutics Classification System (BCS), ranitidine hydrochloride should be assigned to Class III. However, based on its therapeutic and therapeutic index, pharmacokinetic properties and data related to the possibility of excipient interactions, a biowaiver can be recommended for IR solid oral dosage forms that are rapidly dissolving and contain only those excipients as reported in this study.

Journal of Controlled Release, 2012

Detailed understanding of the uptake mechanisms and intracellular processing of nonviral gene del... more Detailed understanding of the uptake mechanisms and intracellular processing of nonviral gene delivery systems will allow design of more effective carriers. This work gets insight into the intracellular kinetics of pDNA delivered by polyethyleneimine (PEI), cationic lipid DOTAP and calcium phosphate (CaP) precipitates. Amount of cell- and nuclear-associated pDNA was quantified by qRT-PCR at multiple time points after transfection. Moreover, the impact of specific endocytic pathways on the cell entry and intracellular kinetics of pDNA was studied by inhibition (blockage) of either clathrin- or dynamin-mediated endocytosis by using both genetically manipulated cell lines and chemical inhibitors of endocytosis. Quantitative analysis of defined kinetic parameters revealed that neither cellular nor nuclear uptake of pDNA correlated with transgene expression, emphasizing the importance of the post-nuclear processes in overall transfection efficacy. Changes in transgene expression observed upon blockage of endocytosis was carrier dependent and correlated relatively well with the changes at the cellular and nuclear uptake levels but not with the amount of cell-associated pDNA. Due to low specificity of chemical inhibitors and activation of alternative endocytosis pathways after genetic blockage of endocytosis neither of these methods is optimal for studying the role of endocytosis. Therefore, one should be careful when interpreting the obtained results from such studies and not to trust the data obtained only from one method.

Journal of Clinical Nursing, 2011

Aims and objectives. To examine the incidence of prescribing errors in a main public hospital in ... more Aims and objectives. To examine the incidence of prescribing errors in a main public hospital in Pakistan and to assess the impact of introducing electronic prescribing system on the reduction of their incidence. Background. Medication errors are persistent in today's healthcare system. The impact of electronic prescribing on reducing errors has not been tested in developing world. Design. Prospective review of medication and discharge medication charts before and after the introduction of an electronic inpatient record and prescribing system. Methods. Inpatient records (n = 3300) and 1100 discharge medication sheets were reviewed for prescribing errors before and after the installation of electronic prescribing system in 11 wards. Results. Medications (13,328 and 14,064) were prescribed for inpatients, among which 3008 and 1147 prescribing errors were identified, giving an overall error rate of 22AE6% and 8AE2% throughout paper-based and electronic prescribing, respectively. Medications (2480 and 2790) were prescribed for discharge patients, among which 418 and 123 errors were detected, giving an overall error rate of 16AE9% and 4AE4% during paper-based and electronic prescribing, respectively. Conclusion. Electronic prescribing has a significant effect on the reduction of prescribing errors. Relevance to clinical practice. Prescribing errors are commonplace in Pakistan public hospitals. The study evaluated the impact of introducing electronic inpatient records and electronic prescribing in the reduction of prescribing errors in a public hospital in Pakistan.

Drug Discovery Today, 2010

ABSTRACT The photoexcited transient states of octadecylrhodamine B (R) and 2-(9-anthroyloxy) stea... more ABSTRACT The photoexcited transient states of octadecylrhodamine B (R) and 2-(9-anthroyloxy) stearic acid (A) mixed in a stearic acid matrix have been studied by flash photolysis and picosecond fluorescence methods in Langmuir-Blodgett films. The two dominant excitation energy relaxation processes for the R monomer are an electron transfer from A to the excited singlet state of R and an energy transfer to the non-fluorescent R dimer. The excited R dimer relaxes via its triplet state. A charge separation process takes place in the triplet state leading to a radical pair.

Bioorganic & Medicinal Chemistry, 2015

SL-3111 [1-(4-tert-butyl-3'-hydroxy)benzhydryl-4-benzylpiperazine] is a de novo designed,... more SL-3111 [1-(4-tert-butyl-3'-hydroxy)benzhydryl-4-benzylpiperazine] is a de novo designed, high-affinity and selective nonpeptide peptidomimetic agonist of the delta-opioid receptor. In a previous report we had described the unique biological characteristics of this ligand and also a need for further structural evaluation.(6) To pursue this, we have introduced a completely different heterocyclic template (2 and 3), which, based on molecular modeling studies, may present the required structural features to properly orient the pharmacophore groups. We also have made more subtle changes to the original piperazine scaffold (5 and 11). The biological activities of these compounds revealed an important participation of the scaffold in the ligand-receptor interaction. To further explore functional diversity on the scaffold, we have maintained the original piperazine ring and introduced four different functionalities at position 2 of the heterocyclic ring (15a-d; a = CH(2)-O-CH(2)-Ph; b = Me; c = CH(2)Ph; d = CH(2)OH). The biological activities observed for these compounds showed a very interesting trend in terms of the steric effects of the groups introduced at this position. A decrease of almost 2000-fold in affinity and potency at the delta-receptor was observed for 15c compared with 15b. This difference may be explained if we postulate that the bioactive conformation of these peptidomimetics is close to the minimal energy conformations calculated in our study. On the basis of these findings we have realized the importance of this position to further explore and simplify the structure of future generations of peptidomimetic ligands.

Drug delivery and translational research, 2014

In this study, chondrocytes were encapsulated into an injectable, in situ forming type II collage... more In this study, chondrocytes were encapsulated into an injectable, in situ forming type II collagen/hyaluronic acid (HA) hydrogel cross-linked with poly(ethylene glycol) ether tetrasuccinimidyl glutarate (4SPEG) and supplemented with the transforming growth factor β1 (TGFβ1). The chondrocyte-hydrogel constructs were cultured in vitro for 7 days and studied for cell viability and proliferation, morphology, glycosaminoglycan production, and gene expression. Type II collagen/HA/4SPEG formed a strong and stable hydrogel, and the chondrocytes remained viable during the encapsulation process and for the 7-day culture period. In addition, the encapsulated cells showed spherical morphology characteristic for chondrocytic phenotype. The cells were able to produce glycosaminoglycans into their extracellular matrix, and the gene expression of type II collagen and aggrecan, genes specific for differentiated chondrocytes, increased over time. The results indicate that the studied composite hydrog...

Biomaterials, 2015

The environmental cues received by the cells from synthetic substrates in vitro are very differen... more The environmental cues received by the cells from synthetic substrates in vitro are very different from those they receive in vivo. In this study, we applied the Langmuir-Schaefer (LS) deposition, a variant of Langmuir-Blodgett technique, to fabricate a biomimetic microenvironment mimicking the structure and organization of native Bruch's membrane for the production of the functional human embryonic stem cell derived retinal pigment epithelial (hESC-RPE) cells. Surface pressure-area isotherms were measured simultaneously with Brewster angle microscopy to investigate the self-assembly of human collagens type I and IV on air-subphase interface. Furthermore, the structure of the prepared collagen LS films was characterized with scanning electron microscopy, atomic force microscopy, surface plasmon resonance measurements and immunofluorescent staining. The integrity of hESC-RPE on double layer LS films was investigated by measuring transepithelial resistance and permeability of smal...

Biosensors, 2013

In this article, we report on the formation and mode-of-operation of an affinity biosensor, where... more In this article, we report on the formation and mode-of-operation of an affinity biosensor, where alternate layers of biotin/streptavidin/biotinylated-CRP-antigen/anti-CRP antibody are grown on printed gold electrodes on disposable paper-substrates. We have successfully demonstrated and detected the formation of consecutive layers of supra-molecular protein assembly using an electrical (impedimetric) technique. The formation process is also supplemented and verified using conventional surface plasmon resonance (SPR) measurements and surface sensitive characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The article provides a possible biosensor development scheme, where-(1) fabrication of paper substrate (2) synthesis of gold nanoparticle inks (3) inkjet printing of gold electrodes on paper (4) formation of the biorecognition layers on the gold electrodes and (5) electrical (impedimetric) analysis of growth-all are coupled tog...

International journal of pharmaceutics, Jan 28, 2013

Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is ... more Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is based on drying of aerosol droplets in continuous flow. We investigated the applicability of aerosol flow reactor method to prepare solid state DNA nanoparticles. Precursor solutions of plasmid DNA with or without complexing agent (polyethylenimine), coating material (l-leucine) and mannitol (bulking material) were dispersed to nanosized droplets and instantly dried in laminar heat flow. Particle morphology, integrity and stability were studied by scanning electron microscopy. The stability of DNA was studied by gel electrophoresis. Plasmid DNA as such degraded in the aerosol flow process. Complexing agent protected DNA from degradation and coating material enabled production of dispersed, non-aggregated, nanoparticles. The resulting nanoparticles were spherical and their mean diameter ranged from 65 to 125nm. The nanoparticles were structurally stable at room temperature and their DNA c...

International journal of pharmaceutics, Jan 28, 2011

This study was conducted to develop a high throughput screening (HTS) method for the assessment o... more This study was conducted to develop a high throughput screening (HTS) method for the assessment of equilibrium solubility of drugs. Solid-state compounds were precipitated from methanol in 96-well plates, in order to eliminate the effect of co-solvent. Solubility of twenty model drugs was analyzed in water and aqueous solutions (pH 1.2 and 6.8) in 96-well plates and in shake-flasks (UV detection). The results obtained with the 96-well plate method correlated well (R(2)=0.93) between the shake-flask and 96-well plates over the wide concentration scale of 0.002-169.2mg/ml. Thereafter, the solubility tests in 96-well plates were performed using fasted state human intestinal fluid (HIF) from duodenum of healthy volunteers. The values of solubility were similar in phosphate buffer solution (pH 6.8) and HIF over the solubility range of 10(2)-10(5)μg/ml. The new 96-well plate method is useful for the screening of equilibrium drug solubility during the drug discovery process and it also all...

International journal of pharmaceutics, Jan 13, 2006

The purpose of this study was to evaluate the feasibility of organotypic cultures of rat epiderma... more The purpose of this study was to evaluate the feasibility of organotypic cultures of rat epidermal cells as a tool to study non-invasive dermal gene delivery. Also, a novel transfection method employing liposomal pre-treatment of stratum corneum (SC) was evaluated. Rat epidermal cells were cultured on Transwell tissue culture inserts and formation of stratum corneum barrier was evaluated in permeability studies with two model compounds. Transfections were performed with naked pCMV-SEAP2 plasmid and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/dioleyl-phosphatidylethanolamine (DOPE)/DNA lipoplexes. Naked DNA was administered on the stratum corneum of the cell culture model with or without prior treatment of the stratum corneum with DOTAP/DOPE liposomes. Transfection was evaluated non-invasively by monitoring concentrations of secreted alkaline phosphatase (SEAP) in the culture medium of the basolateral compartment at 24-h intervals. Transfection with lipoplexes produced significa...

Advances in Biomaterials Science and Biomedical Applications, 2013

The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The ... more The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The goal of this study was to characterise the paracellular permeation pathway in the human intestinal wall and differentiated epithelial cell models (MDCKII, Caco-2 and 2/4/A1). The permeabilities of hydrophilic polyethylene glycols (PEG) were investigated in diffusion chambers, and mass spectrometry was used to obtain accurate concentrations for each PEG molecule. The paracellular porosity and the size of the pores in the membranes were estimated from the PEG permeability data using an effusion-based approach. The porosities were found to be low (fraction 10(-7)-10(-5) of the epithelial surface) in all investigated membranes. Two different pore sizes (radii 5-6 and >10 A) were detected in the human intestinal epithelium and the Caco-2 and MDCKII cells, while only one (about 15 A) in the 2/4/A1 monolayer. The paracellular porosities of the human small intestine and 2/4/A1 monolayers were larger (>10(-7)) than that of the MDCKII and Caco-2 cells (<10(-7)). We report for the first time the quantitative values describing both porosity and pore size of the paracellular space in the human intestine. The cell models deviate from the small intestine either with respect to porosity (Caco-2, MDCKII) or pore size distribution (2/4/A1).

PLoS ONE, 2013

In vitro cell-based assays are widely used during the drug discovery and development process to t... more In vitro cell-based assays are widely used during the drug discovery and development process to test the biological activity of new drugs. Most of the commonly used cell-based assays, however, lack the ability to measure in real-time or under dynamic conditions (e.g. constant flow). In this study a multi-parameter surface plasmon resonance approach in combination with living cell sensing has been utilized for monitoring drug-cell interactions in real-time, under constant flow and without labels. The multi-parameter surface plasmon resonance approach, i.e. surface plasmon resonance angle versus intensity plots, provided fully specific signal patterns for various cell behaviors when stimulating cells with drugs that use para-and transcellular absorption routes. Simulated full surface plasmon resonance angular spectra of cell monolayers were compared with actual surface plasmon resonance measurements performed with MDCKII cell monolayers in order to better understand the origin of the surface plasmon resonance signal responses during drug stimulation of cells. The comparison of the simulated and measured surface plasmon resonance responses allowed to better understand and provide plausible explanations for the type of cellular changes, e.g. morphological or mass redistribution in cells, that were induced in the MDCKII cell monolayers during drug stimulation, and consequently to differentiate between the type and modes of drug actions. The multi-parameter surface plasmon resonance approach presented in this study lays the foundation for developing new types of cell-based tools for life science research, which should contribute to an improved mechanistic understanding of the type and contribution of different drug transport routes on drug absorption.

The Journal of Physical Chemistry, 1989

... (13) Blackwell, M. F.; Gounaris, K.; Zara, S. J.; Barber, J. Biophys. J . 1986, 51, 735. (14)... more ... (13) Blackwell, M. F.; Gounaris, K.; Zara, S. J.; Barber, J. Biophys. J . 1986, 51, 735. (14) Thuren, T.; Vainio, P.; Virtanen, J. A.; Somerharju, P.; Blomqvist, K.; Kinnunen, PKJ Biochemistry 1984, 23, 5129. (15) Thuren, T.; Virtanen, JA; Lalla, M.; Kinnunen, PKJ Clin. Chem. ...

Journal of pharmaceutical sciences, 2005

Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequival... more Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequivalence testing for the approval of immediate release (IR) solid oral dosage forms containing ranitidine hydrochloride are reviewed. According to the current Biopharmaceutics Classification System (BCS), ranitidine hydrochloride should be assigned to Class III. However, based on its therapeutic and therapeutic index, pharmacokinetic properties and data related to the possibility of excipient interactions, a biowaiver can be recommended for IR solid oral dosage forms that are rapidly dissolving and contain only those excipients as reported in this study.

Journal of Controlled Release, 2012

Detailed understanding of the uptake mechanisms and intracellular processing of nonviral gene del... more Detailed understanding of the uptake mechanisms and intracellular processing of nonviral gene delivery systems will allow design of more effective carriers. This work gets insight into the intracellular kinetics of pDNA delivered by polyethyleneimine (PEI), cationic lipid DOTAP and calcium phosphate (CaP) precipitates. Amount of cell- and nuclear-associated pDNA was quantified by qRT-PCR at multiple time points after transfection. Moreover, the impact of specific endocytic pathways on the cell entry and intracellular kinetics of pDNA was studied by inhibition (blockage) of either clathrin- or dynamin-mediated endocytosis by using both genetically manipulated cell lines and chemical inhibitors of endocytosis. Quantitative analysis of defined kinetic parameters revealed that neither cellular nor nuclear uptake of pDNA correlated with transgene expression, emphasizing the importance of the post-nuclear processes in overall transfection efficacy. Changes in transgene expression observed upon blockage of endocytosis was carrier dependent and correlated relatively well with the changes at the cellular and nuclear uptake levels but not with the amount of cell-associated pDNA. Due to low specificity of chemical inhibitors and activation of alternative endocytosis pathways after genetic blockage of endocytosis neither of these methods is optimal for studying the role of endocytosis. Therefore, one should be careful when interpreting the obtained results from such studies and not to trust the data obtained only from one method.

Journal of Clinical Nursing, 2011

Aims and objectives. To examine the incidence of prescribing errors in a main public hospital in ... more Aims and objectives. To examine the incidence of prescribing errors in a main public hospital in Pakistan and to assess the impact of introducing electronic prescribing system on the reduction of their incidence. Background. Medication errors are persistent in today's healthcare system. The impact of electronic prescribing on reducing errors has not been tested in developing world. Design. Prospective review of medication and discharge medication charts before and after the introduction of an electronic inpatient record and prescribing system. Methods. Inpatient records (n = 3300) and 1100 discharge medication sheets were reviewed for prescribing errors before and after the installation of electronic prescribing system in 11 wards. Results. Medications (13,328 and 14,064) were prescribed for inpatients, among which 3008 and 1147 prescribing errors were identified, giving an overall error rate of 22AE6% and 8AE2% throughout paper-based and electronic prescribing, respectively. Medications (2480 and 2790) were prescribed for discharge patients, among which 418 and 123 errors were detected, giving an overall error rate of 16AE9% and 4AE4% during paper-based and electronic prescribing, respectively. Conclusion. Electronic prescribing has a significant effect on the reduction of prescribing errors. Relevance to clinical practice. Prescribing errors are commonplace in Pakistan public hospitals. The study evaluated the impact of introducing electronic inpatient records and electronic prescribing in the reduction of prescribing errors in a public hospital in Pakistan.

Drug Discovery Today, 2010

ABSTRACT The photoexcited transient states of octadecylrhodamine B (R) and 2-(9-anthroyloxy) stea... more ABSTRACT The photoexcited transient states of octadecylrhodamine B (R) and 2-(9-anthroyloxy) stearic acid (A) mixed in a stearic acid matrix have been studied by flash photolysis and picosecond fluorescence methods in Langmuir-Blodgett films. The two dominant excitation energy relaxation processes for the R monomer are an electron transfer from A to the excited singlet state of R and an energy transfer to the non-fluorescent R dimer. The excited R dimer relaxes via its triplet state. A charge separation process takes place in the triplet state leading to a radical pair.

Bioorganic & Medicinal Chemistry, 2015

SL-3111 [1-(4-tert-butyl-3'-hydroxy)benzhydryl-4-benzylpiperazine] is a de novo designed,... more SL-3111 [1-(4-tert-butyl-3'-hydroxy)benzhydryl-4-benzylpiperazine] is a de novo designed, high-affinity and selective nonpeptide peptidomimetic agonist of the delta-opioid receptor. In a previous report we had described the unique biological characteristics of this ligand and also a need for further structural evaluation.(6) To pursue this, we have introduced a completely different heterocyclic template (2 and 3), which, based on molecular modeling studies, may present the required structural features to properly orient the pharmacophore groups. We also have made more subtle changes to the original piperazine scaffold (5 and 11). The biological activities of these compounds revealed an important participation of the scaffold in the ligand-receptor interaction. To further explore functional diversity on the scaffold, we have maintained the original piperazine ring and introduced four different functionalities at position 2 of the heterocyclic ring (15a-d; a = CH(2)-O-CH(2)-Ph; b = Me; c = CH(2)Ph; d = CH(2)OH). The biological activities observed for these compounds showed a very interesting trend in terms of the steric effects of the groups introduced at this position. A decrease of almost 2000-fold in affinity and potency at the delta-receptor was observed for 15c compared with 15b. This difference may be explained if we postulate that the bioactive conformation of these peptidomimetics is close to the minimal energy conformations calculated in our study. On the basis of these findings we have realized the importance of this position to further explore and simplify the structure of future generations of peptidomimetic ligands.

Drug delivery and translational research, 2014

In this study, chondrocytes were encapsulated into an injectable, in situ forming type II collage... more In this study, chondrocytes were encapsulated into an injectable, in situ forming type II collagen/hyaluronic acid (HA) hydrogel cross-linked with poly(ethylene glycol) ether tetrasuccinimidyl glutarate (4SPEG) and supplemented with the transforming growth factor β1 (TGFβ1). The chondrocyte-hydrogel constructs were cultured in vitro for 7 days and studied for cell viability and proliferation, morphology, glycosaminoglycan production, and gene expression. Type II collagen/HA/4SPEG formed a strong and stable hydrogel, and the chondrocytes remained viable during the encapsulation process and for the 7-day culture period. In addition, the encapsulated cells showed spherical morphology characteristic for chondrocytic phenotype. The cells were able to produce glycosaminoglycans into their extracellular matrix, and the gene expression of type II collagen and aggrecan, genes specific for differentiated chondrocytes, increased over time. The results indicate that the studied composite hydrog...

Biomaterials, 2015

The environmental cues received by the cells from synthetic substrates in vitro are very differen... more The environmental cues received by the cells from synthetic substrates in vitro are very different from those they receive in vivo. In this study, we applied the Langmuir-Schaefer (LS) deposition, a variant of Langmuir-Blodgett technique, to fabricate a biomimetic microenvironment mimicking the structure and organization of native Bruch's membrane for the production of the functional human embryonic stem cell derived retinal pigment epithelial (hESC-RPE) cells. Surface pressure-area isotherms were measured simultaneously with Brewster angle microscopy to investigate the self-assembly of human collagens type I and IV on air-subphase interface. Furthermore, the structure of the prepared collagen LS films was characterized with scanning electron microscopy, atomic force microscopy, surface plasmon resonance measurements and immunofluorescent staining. The integrity of hESC-RPE on double layer LS films was investigated by measuring transepithelial resistance and permeability of smal...

Biosensors, 2013

In this article, we report on the formation and mode-of-operation of an affinity biosensor, where... more In this article, we report on the formation and mode-of-operation of an affinity biosensor, where alternate layers of biotin/streptavidin/biotinylated-CRP-antigen/anti-CRP antibody are grown on printed gold electrodes on disposable paper-substrates. We have successfully demonstrated and detected the formation of consecutive layers of supra-molecular protein assembly using an electrical (impedimetric) technique. The formation process is also supplemented and verified using conventional surface plasmon resonance (SPR) measurements and surface sensitive characterization techniques, such as X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The article provides a possible biosensor development scheme, where-(1) fabrication of paper substrate (2) synthesis of gold nanoparticle inks (3) inkjet printing of gold electrodes on paper (4) formation of the biorecognition layers on the gold electrodes and (5) electrical (impedimetric) analysis of growth-all are coupled tog...

International journal of pharmaceutics, Jan 28, 2013

Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is ... more Aerosol flow reactor is used to generate solid-state nanoparticles in a one-step process that is based on drying of aerosol droplets in continuous flow. We investigated the applicability of aerosol flow reactor method to prepare solid state DNA nanoparticles. Precursor solutions of plasmid DNA with or without complexing agent (polyethylenimine), coating material (l-leucine) and mannitol (bulking material) were dispersed to nanosized droplets and instantly dried in laminar heat flow. Particle morphology, integrity and stability were studied by scanning electron microscopy. The stability of DNA was studied by gel electrophoresis. Plasmid DNA as such degraded in the aerosol flow process. Complexing agent protected DNA from degradation and coating material enabled production of dispersed, non-aggregated, nanoparticles. The resulting nanoparticles were spherical and their mean diameter ranged from 65 to 125nm. The nanoparticles were structurally stable at room temperature and their DNA c...

International journal of pharmaceutics, Jan 28, 2011

This study was conducted to develop a high throughput screening (HTS) method for the assessment o... more This study was conducted to develop a high throughput screening (HTS) method for the assessment of equilibrium solubility of drugs. Solid-state compounds were precipitated from methanol in 96-well plates, in order to eliminate the effect of co-solvent. Solubility of twenty model drugs was analyzed in water and aqueous solutions (pH 1.2 and 6.8) in 96-well plates and in shake-flasks (UV detection). The results obtained with the 96-well plate method correlated well (R(2)=0.93) between the shake-flask and 96-well plates over the wide concentration scale of 0.002-169.2mg/ml. Thereafter, the solubility tests in 96-well plates were performed using fasted state human intestinal fluid (HIF) from duodenum of healthy volunteers. The values of solubility were similar in phosphate buffer solution (pH 6.8) and HIF over the solubility range of 10(2)-10(5)μg/ml. The new 96-well plate method is useful for the screening of equilibrium drug solubility during the drug discovery process and it also all...

International journal of pharmaceutics, Jan 13, 2006

The purpose of this study was to evaluate the feasibility of organotypic cultures of rat epiderma... more The purpose of this study was to evaluate the feasibility of organotypic cultures of rat epidermal cells as a tool to study non-invasive dermal gene delivery. Also, a novel transfection method employing liposomal pre-treatment of stratum corneum (SC) was evaluated. Rat epidermal cells were cultured on Transwell tissue culture inserts and formation of stratum corneum barrier was evaluated in permeability studies with two model compounds. Transfections were performed with naked pCMV-SEAP2 plasmid and 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/dioleyl-phosphatidylethanolamine (DOPE)/DNA lipoplexes. Naked DNA was administered on the stratum corneum of the cell culture model with or without prior treatment of the stratum corneum with DOTAP/DOPE liposomes. Transfection was evaluated non-invasively by monitoring concentrations of secreted alkaline phosphatase (SEAP) in the culture medium of the basolateral compartment at 24-h intervals. Transfection with lipoplexes produced significa...

Advances in Biomaterials Science and Biomedical Applications, 2013

The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The ... more The paracellular space defines the passive permeation of hydrophilic compounds in epithelia. The goal of this study was to characterise the paracellular permeation pathway in the human intestinal wall and differentiated epithelial cell models (MDCKII, Caco-2 and 2/4/A1). The permeabilities of hydrophilic polyethylene glycols (PEG) were investigated in diffusion chambers, and mass spectrometry was used to obtain accurate concentrations for each PEG molecule. The paracellular porosity and the size of the pores in the membranes were estimated from the PEG permeability data using an effusion-based approach. The porosities were found to be low (fraction 10(-7)-10(-5) of the epithelial surface) in all investigated membranes. Two different pore sizes (radii 5-6 and >10 A) were detected in the human intestinal epithelium and the Caco-2 and MDCKII cells, while only one (about 15 A) in the 2/4/A1 monolayer. The paracellular porosities of the human small intestine and 2/4/A1 monolayers were larger (>10(-7)) than that of the MDCKII and Caco-2 cells (<10(-7)). We report for the first time the quantitative values describing both porosity and pore size of the paracellular space in the human intestine. The cell models deviate from the small intestine either with respect to porosity (Caco-2, MDCKII) or pore size distribution (2/4/A1).

PLoS ONE, 2013

In vitro cell-based assays are widely used during the drug discovery and development process to t... more In vitro cell-based assays are widely used during the drug discovery and development process to test the biological activity of new drugs. Most of the commonly used cell-based assays, however, lack the ability to measure in real-time or under dynamic conditions (e.g. constant flow). In this study a multi-parameter surface plasmon resonance approach in combination with living cell sensing has been utilized for monitoring drug-cell interactions in real-time, under constant flow and without labels. The multi-parameter surface plasmon resonance approach, i.e. surface plasmon resonance angle versus intensity plots, provided fully specific signal patterns for various cell behaviors when stimulating cells with drugs that use para-and transcellular absorption routes. Simulated full surface plasmon resonance angular spectra of cell monolayers were compared with actual surface plasmon resonance measurements performed with MDCKII cell monolayers in order to better understand the origin of the surface plasmon resonance signal responses during drug stimulation of cells. The comparison of the simulated and measured surface plasmon resonance responses allowed to better understand and provide plausible explanations for the type of cellular changes, e.g. morphological or mass redistribution in cells, that were induced in the MDCKII cell monolayers during drug stimulation, and consequently to differentiate between the type and modes of drug actions. The multi-parameter surface plasmon resonance approach presented in this study lays the foundation for developing new types of cell-based tools for life science research, which should contribute to an improved mechanistic understanding of the type and contribution of different drug transport routes on drug absorption.

The Journal of Physical Chemistry, 1989

... (13) Blackwell, M. F.; Gounaris, K.; Zara, S. J.; Barber, J. Biophys. J . 1986, 51, 735. (14)... more ... (13) Blackwell, M. F.; Gounaris, K.; Zara, S. J.; Barber, J. Biophys. J . 1986, 51, 735. (14) Thuren, T.; Vainio, P.; Virtanen, J. A.; Somerharju, P.; Blomqvist, K.; Kinnunen, PKJ Biochemistry 1984, 23, 5129. (15) Thuren, T.; Virtanen, JA; Lalla, M.; Kinnunen, PKJ Clin. Chem. ...