Eleonore Haltner - Academia.edu (original) (raw)

Papers by Eleonore Haltner

International Journal of Pharmaceutics, Dec 1, 2000

A positively charged self-emulsifying oil formulation (SEOF), aimed to enhance oral bioavailabili... more A positively charged self-emulsifying oil formulation (SEOF), aimed to enhance oral bioavailability of drugs poorly soluble in water, was recently developed. In the present study the Caco-2 cell model was used for the investigation of the charge-dependent interactions of this SEOF with human intestinal epithelial cells. The positively charged emulsions affected the barrier properties of the cell monolayer at high concentrations and reduced the cell viability. However, at the dilution with aqueous phase used in the present study (1:2000), the positively charged SEOF did not induce any detectable cytotoxic effect. The binding of the fluorescent dye DiIC(18)(3) was much higher from the positively charged SEOF, compared to the negatively charged formulation, suggesting an increased closer adhesion of the droplets to the cell surface due to the electrostatic attraction. No transepithelial transport of this compound across Caco-2 cell monolayers was observed with any SEOF formulation.

ALTEX 22, Special Issue 2005 128 While conventional toxicology testing focuses on single chemical... more ALTEX 22, Special Issue 2005 128 While conventional toxicology testing focuses on single chemicals, human exposures are usually to more than one chemical. Most regulatory agencies use the default assumption that the risk of exposures to more than one chemical is treated in an additive manner. This approach may underor over-estimate the risk of chemicals depending on their different modes of action or interaction. Therefore, one objective of combination toxicology is to establish whether exposure to a mixture of chemicals will result in an effect similar to that predicted on the basis of additivity. In this study, human skin fibroblasts were used in the colourimetric MTS (tetrazolium salt; Promega®) and the NRU (Neutral Red Uptake; Sigma) assay to investigate combination toxicology phenomena. Individual IC50 toxicity values for 24 chemicals whose in vivo toxicity was spread over the five Globally Harmonised System (GHS) categories for acute oral toxicity were used to create 18 binary...

Subject: The human cervix is the point of origin of cervical cancer, the second most common femal... more Subject: The human cervix is the point of origin of cervical cancer, the second most common female tumor entity worldwide. Every year about 230,000 women die from cervical cancer. The necessary cause of cervical cancer is the infection of the cervix with high risk types of human papilloma virus (HPV) (Walboomers et al., 1999). To address a local therapy with nucleic acid drugs it is important to understand the barrier properties of the target tissue to which the drug will be applied. The aim of this study was to establish and validate an ex vivo human cervical tissue model for delivery and permeation studies. Material and Methods: Permeability studies were conducted using the static Franz cell system (Hiller et al., 2007). The cervical biopsies of an area of 0.125 cm were inserted with the mucosal side oriented upwards. The transport experiments were performed at 37°C applying a pH gradient (donor pH 6.0/acceptor pH 7.4). 40 μM [14C]Mannitol and [3H]Propanolol were used. [14C]Dextra...

Methods in molecular medicine, 1998

The rapid scientific progress in the areas of gene technology and biotechnology has provided an i... more The rapid scientific progress in the areas of gene technology and biotechnology has provided an increasing number of biologically active compounds, raising the hope that better cures will be available in the near future for a number of severe diseases. However, before such novel biopharmaceuticals (e.g., peptides, proteins, oligonucleotides, gene vectors) can be used for drug therapy in humans, novel ways of drug delivery have to be developed in order to ensure the safe and effictent administration of these compounds to the patient (For general references, see refs 1-4). Certainly, convenient and easy routes of drug administration- ideally by simply swallowing a tablet or capsule-would be preferable to parenteral injections, which are painful and require trained healthcare personnel However, because of their relatively large size, poor lipid solubility, and delicate structure-in contrast to many conventional small drug molecules-the transport of modern biopharmaceuticals across biol...

International Journal of Pharmaceutics, 2000

Pharmaceutical Research, 2006

To characterize the telomerase inhibitor and G-quadruplex stabilizing substance 9-[4-(N,N-dimethy... more To characterize the telomerase inhibitor and G-quadruplex stabilizing substance 9-[4-(N,N-dimethylamino)phenylamino]-3,6-bis (3-pyrrolodino-propionamido) acridine x 3HCl (BRACO19) in terms of biopharmaceutical properties such as solubility, protein binding, interaction with membrane lipids, cytotoxicity, and permeability across pulmonary epithelial cells. Protein binding and interaction with membrane lipids were investigated by two high-performance liquid chromatography methods with immobilized human serum albumin and immobilized phosphatidylcholine, respectively. Cytotoxicity (methyl-thiazolyl-tetrazolium assay) and transport studies were performed with the bronchial cell lines 16HBE14o- and Calu-3, primary human alveolar epithelial cells, and the intestinal cell line Caco-2. Transport experiments were also done in the presence of cyclosporin A (10 microM) and tetraethylammonium chloride (5 mM) and at low temperature (4 degrees C). BRACO19 has good solubility of at least 2 mg/mL in water and in physiological buffers of pH 7.4 and below. Protein binding to human serum albumin was 38%. No interaction with membrane lipids could be found. Cytotoxicity in 16HBE14o-, Calu-3, and human alveolar epithelial cells was in the range of IC50 = 3.5 to 13.5 microM. Caco-2 cells were not affected at concentrations up to 50 microM. No transport of BRACO19 was detected across either cell monolayer in absorptive direction. In secretory direction, permeability was very low, with P (app) values in the range of 0.25 x 10(-7) to 0.98 x 10(-7) cm/s for all epithelial cell cultures tested. The transport was not influenced by cyclosporin A or tetraethylammonium chloride or at 4 degrees C, indicating that no efflux/influx systems or active transport are involved. From these results, we conclude that the very poor permeability of BRACO19 is its main biopharmaceutical limitation. Further applications will require a suitable formulation to warrant adequate delivery across cellular barriers.

European Journal of Pharmaceutics and Biopharmaceutics, 2007

The objective of this work was to compare the barrier function of the small diameter reconstructe... more The objective of this work was to compare the barrier function of the small diameter reconstructed human epidermis model Episkin Ò (d = 12 mm) to human skin in vitro. For that purpose a modification for the Franz diffusion cell (d = 15 mm) had to be developed so as to allow direct comparison with the following human skin preparations: Full thickness skin (FTS), split thickness skin (STS), heat-separated epidermis (HSE), and trypsin isolated stratum corneum (TISC). Among the tested preparations, HSE appeared to be the most preferable due to its clear morphological structure and ease of preparation. The lipid profile of HSE and Episkin Ò was analyzed and showed significant differences in terms of cholesterol, ceramides and triglycerides contents, whereas cholesterol esters and fatty acids were not different. Permeation data with HSE and Episkin Ò were then gathered using caffeine and testosterone. Both test compounds permeated much faster through Episkin Ò than through HSE. Moreover, opposed to Episkin Ò , HSE differentiated between the two test compounds. In spite of the remarkable progress in developing RHEs in the past years at this time Episkin Ò can obviously not yet fully replace human skin for in vitro permeability experiments.

In vitro systems for testing of cutaneous penetration and permeation of topically applied drugs a... more In vitro systems for testing of cutaneous penetration and permeation of topically applied drugs and cosmetic products are an interesting alternative to in vivo animal studies. Standardized procedures are necessary for improving reproducibility and comparability with in vivo data.

Journal of Hepatology, 1993

This study concerns the cooperation of hepatocytes (PC) and Kupffer cells (KC) in the activation ... more This study concerns the cooperation of hepatocytes (PC) and Kupffer cells (KC) in the activation of rat liver fat storing cells (FSC) in culture. Various dilutions of conditioned media collected from early, serum-free cultures of both cell types were added separately and in combination, either simultaneously or sequentially, to early, non-confluent, primary cultures of FSC maintained under serum-reduced (0.5% fetal calf serum) conditions to determine the effects on proliferation (incorporations of [3H]thymidine and bromodeoxyuridine [BrdUrd], DNA-content, cell number), transformation and morphology (phase contrast microscopy, immunostainings of desmin and smooth muscle-alpha-actin), on the deposition of fibronectin and laminin and on the formation of 35S sulfated medium proteoglycans. Media of both cell types stimulated cell proliferation in a dose-dependent manner but combined PC- and KC-conditioned media was most potent and increased the incorporation of [3H]thymidine to 4-times above control values. The multiplication stimulatory effects visualized by labeling cell nuclei with BrdUrd and the increase of cell number per culture well were additive. The sequential addition of KC-conditioned medium to FSC preexposed to PC-conditioned medium increased the multiplication of FSC further and in an additive manner. The mitogenic activity of the PC-medium and the enhancing effect of KC-induced FSC proliferation was measured also when PC were damaged by incubation under anoxic conditions during generation of the conditioned medium. This observation indicates the release of the mitogen by membrane damage presumably from a cytoplasmic pool. The PC-medium did not induce either significant morphological changes or transformation of FSC towards myofibroblast-like cells. KC, however, generated transformation of FSC as indicated by more elongated cells with spindle-like cellular extensions and a reduction of retinoid droplets. Both these morphological effects were visible when PC and KC media were added simultaneously. Both media act synergistically on the deposition of fibronectin and laminin in FSC cultures and these components were found to be elevated 2.3 and 2.8-fold, respectively, if the cells were exposed to the combined media. Proteoglycan synthesis was also maximally enhanced if FSC were exposed to PC- and KC-media simultaneously. These findings suggest the involvement of (damaged) hepatocytes in the process of FSC activation. A model of sequential, spatial and time-dependent activation of FSC is suggested where cells in the immediate proximity of hepatocytes are primed to proliferate by a mitogenic signal released by membrane damage presumably from a cytoplasmic pool of injured hepatocytes into the pericellular environment. This non-inflammatory stimulation is followed by secretions of activated Kupffer cells and other inflammatory cell types which further enhance the activation of FSC.(ABSTRACT TRUNCATED AT 400 WORDS)

The Essential Stratum Corneum, 2002

INTRODUCTION Generics represent an important part of new products on market. However there is a n... more INTRODUCTION Generics represent an important part of new products on market. However there is a necessity to prove the equivalence between originator and generic products to obtain marketing authorization. The World Health Organization defines two products as therapeutically equivalent if they are pharmaceutically equivalent at the same dose and demonstrate similar safety and efficacy based on bioequivalence, pharmacodynamics, clinical or in-vitro studies; therapeutic equivalence is then assumed without requiring further supportive evidence (1).

Slovenian Veterinary Research, 2020

The employment of excised skin (human or animal) mounted in diffusion cells is frequently used fo... more The employment of excised skin (human or animal) mounted in diffusion cells is frequently used for the characterization of biopharmaceutical properties of topical semisolids dosage forms. Reptile skin from snake appears to be a useful alternative to other animal and human skins in assessing the potential for transdermal drug delivery. The aim of the study was to compare human and snake skin from a histological point of view. Furthermore the absorption of caffeine, as a hydrophilic model substance, was compared on snake shed skins (two anatomical locations; ventral and dorsal), from three different species, Python regius , Epicrates maurus colombianus , Lampropeltis triangulum campbelli , and human skin. Snake skin shows histological similarity to human Stratum corneum in term of thickness and composition. Regarding the absorption, the cumulative amount of caffeine increased linearly with time through the dorsal and ventral shed skins of all 3 species. Except for Lampropeltis trian...

PeerJ, 2019

Transdermal drug delivery provides several advantages over conventional drug administration, such... more Transdermal drug delivery provides several advantages over conventional drug administration, such as the avoidance of first-pass metabolism and better patient compliance. In vitro research can abbreviate and facilitate the pharmaceutical development considerably compared to in vivo research as drug screening and clinical studies can be reduced. These advantages led to the development of corresponding skin models. Viable skin models are more useful than non-viable ones, due to the influence of skin metabolism on the results. While most in vitro studies concentrate on evaluating human-based models, the current study is designed for the investigation of both human and animal diseases. So far, there is little information available in the literature about viable animal skin cultures which are in fact intended for application in the veterinary and not the human field. Hence, the current study aims to fill the gap. For the in vitro viable skin model, specimens of human, porcine and canine ...

Heliyon, 2019

In view of increasing numbers of dermatological disorders, transdermal drug delivery along with i... more In view of increasing numbers of dermatological disorders, transdermal drug delivery along with in vitro research is becoming increasingly popular. Herefore, qualified in vitro skin models are required. The objective of this study was the optimization and validation of a modified lactate dehydrogenase (LDH) release assay during the establishment of an in vitro viable human skin model, employable for a variety of skin associated disorders. Firstly, the most suitable LDH isoform for the study was determined. Subsequently, a stability study was conducted to investigate the best storage conditions of the LDH enzyme. Finally, the test system was validated in terms of linear range, range limits and system suitability. The results indicate LDH-5 as most suitable isoform due to its predominance in skin. The stability samples stored at À20 C in the presence of polyethylene glycol (PEG) as cryoprotector displayed the targeted recovery of 100% AE 15 % until the end of the four-week study in contrast to other investigated conditions. A six-point calibration without PEG and a seven-point calibration with PEG including evaluation of system suitability and quantification limits were established with both correlation coefficients r 2 above 0.99 and all deviations below 15%. Concluding from those results, this method can be considered valid and useful for its employment in viability determination of viable in vitro skin models.

Journal of Drug Delivery Science and Technology, 2019

Establishment of a novel in vitro viable human skin model as a basis for the treatment of human a... more Establishment of a novel in vitro viable human skin model as a basis for the treatment of human and veterinary chronic skin diseases,

Alternatives to Laboratory Animals, 2006

Exposure to chemicals absorbed by the skin can threaten human health. In order to standardise the... more Exposure to chemicals absorbed by the skin can threaten human health. In order to standardise the predictive testing of percutaneous absorption for regulatory purposes, the OECD adopted guideline 428, which describes methods for assessing absorption by using human and animal skin. In this study, a protocol based on the OECD principles was developed and prevalidated by using reconstructed human epidermis (RHE). The permeation of the OECD standard compounds, caffeine and testosterone, through commercially available RHE models was compared to that of human epidermis and animal skin. In comparison to human epidermis, the permeation of the chemicals was overestimated when using RHE. The following ranking of the permeation coefficients for testosterone was obtained: SkinEthic > EpiDerm, EPISKIN > human epidermis, bovine udder skin, pig skin. The ranking for caffeine was: SkinEthic, EPISKIN > bovine udder skin, EpiDerm, pig skin, human epidermis. The inter-laboratory and intra-lab...

Alternatives to Laboratory Animals, 2008

A formal validation study was performed, in order to investigate whether the commercially-availab... more A formal validation study was performed, in order to investigate whether the commercially-available reconstructed human epidermis (RHE) models, EPISKIN®, EpiDerm™ and SkinEthic®, are suitable for in vitro skin absorption testing. The skin types currently recommended in the OECD Test Guideline 428, namely, ex vivo human epidermis and pig skin, were used as references. Based on the promising outcome of the prevalidation study, the panel of test substances was enlarged to nine substances, covering a wider spectrum of physicochemical properties. The substances were tested under both infinite-dose and finite-dose conditions, in ten laboratories, under strictly controlled conditions. The data were subjected to independent statistical analyses. Intra-laboratory and inter-laboratory variability contributed almost equally to the total variability, which was in the same range as that in preceding studies. In general, permeation of the RHE models exceeded that of human epidermis and pig skin (...