Adaptive resistance of Saccharomyces cerevisiae to chronic treatment with genotoxic and nongenotoxic carcinogens.

The exposure of mammalian cells or tumors for weeks or months to low nonlethal doses of cytostatic drugs may induce multidrug resistance, which can be enhanced by a variety of DNA-damaging agents. Multidrug resistance to a variety of drugs has been observed. But in yeast, DNA-damaging agents have not yet been tested.

Novel approaches for studying pulmonary toxicity in vitro.

The in vitro study of adverse cellular effects induced by inhaled pollutants poses a special problem due to the difficulties of exposing cultured cells of the respiratory tract directly to test atmospheres that can include complex gaseous and particulate mixtures. In general, there is no widely accepted in vitro exposure system. However, in vitro methods offer the unique possibility for use of human cells, developed and validated cell culture and exposure device (CULTEX(1)) using the principle of the air/liquid exposure technique.

Local release of eosinophil peroxidase following segmental allergen provocation in asthma.

Background: Eosinophil peroxidase (EPO) is an eosinophilic basic protein, which leads to increased permeability and damage of bronchial epithelial cells in asthma.

Objective: As little is known about its local expression and release in humans the intracellular expression in lung and peripheral eosinophils and the concentrations of EPO in bronchoalveolar lavage (BAL) fluid and serum was investigated in patients with asthma.

Methods: Twelve mild atopic asthmatic and nine control subjects underwent segmental sham and allergen challenge.

PCBs alter gene expression of nuclear transcription factors and other heart-specific genes in cultures of primary cardiomyocytes: possible implications for cardiotoxicity.

1. Polychlorinated biphenyls (PCBs) are well-known environmental pollutants that bioaccumulate mainly in the fatty tissue of animals and humans. Although contamination occurs primarily via the food chain, waste combustion leads to airborne PCBs.

Development of a gas chromatography-mass spectrometry method for the determination of household insecticides in indoor air.

This work presents a GC-MS method for the determination of 17 household insecticides and acaricides in indoor air. Air samples were collected with a sampling train which consisted of a glass fibre filter and two polyurethane foam plugs, followed by a high-volume air pump. Filters and plugs were analysed separately.

Exposure of human lung cells to inhalable substances: a novel test strategy involving clean air exposure periods using whole diluted cigarette mainstream smoke.

An experimental approach was established for the validation of an in vitro test system for complex environmental test atmospheres consisting of both gaseous substances and particulates. Smoke from two different cigarette types (generated by an automatic cigarette-smoking machine) was employed to assess both the sensitivity and the specificity of the system. The smoke was diluted with synthetic air and used to expose human lung cells grown on microporous membranes.

Application of restricted access material (RAM) with precolumn-switching and matrix solid-phase dispersion (MSPD) to the study of the metabolism and pharmacokinetics of Verapamil.

In the pharmaceutical industry, studies of the metabolism and pharmacokinetics of drugs are important routine applications which require the analysis of the precursor drug and its metabolites in various biological matrices, such as plasma, serum, urine, cell culture media and tissue samples. In this study, two new and simple methods of sample preparation were optimized and validated: on the one hand, a column-switching technique with a restricted access material (RAM) was used to analyze biological fluids, and on the other hand, matrix solid-phase dispersion (MSPD) was applied to the extraction of analytes from tissue samples. Identification of the metabolites was done with a LC-MS system (ion trap in the MS(n)mode) coupled both on-line (RAM) and off-line (MSPD).

Indoor pyrethroid exposure in homes with woollen textile floor coverings.

In order to investigate human's exposure to permethrin from treated woollen textile floor coverings and possible adverse health effects, a study was carried out in 80 private homes in Hannover (Germany) equipped with woollen textile floor coverings (wool wall-to-wall carpets or woven or knotted rugs). For indoor monitoring, permethrin was determined both in house dust and on suspended particles. While permethrin concentrations in house dust (< 2 mm) were high (arithmetic mean: 53.

Evaluation of the respicon as a personal inhalable sampler in industrial environments.

The Respicon has been introduced as a sampler for health related measurements of airborne contaminants at workplaces. The instrument is aimed at simultaneous collection of three health related aerosol fractions: (a) the coarser inhalable fraction, defining the aerosol fraction that may enter the nose and mouth during breathing; (b) the intermediate thoracic fraction, defining the fraction that may penetrate beyond the larynx and so reach the lung; and (c) the finer respirable fraction, defining the fraction that may penetrate to gas exchange region of the lung. The instrument has a number of features attractive to occupational hygienists: in addition to providing the three aerosol fractions simultaneously, it is light and compact enough to be used as a personal sampler.

Testosterone, cytochrome P450, and cardiac hypertrophy.

Cytochrome P450 mono-oxygenases (CYP) play an essential role in steroid metabolism, and there is speculation that sex hormones might influence cardiac mass and physiology. As CYP mono-oxygenases activity is frequently altered during disease, we tested our hypothesis that CYP mono-oxygenase expression and testosterone metabolism are altered in cardiac hypertrophy. We investigate major CYP mono-oxygenase isoforms and other steroid-metabolizing enzymes and the androgen receptor in normal, hypertrophic, and assist device-supported human hearts and in spontaneously hypertensive rats (SHR).

Verapamil: new insight into the molecular mechanism of drug oxidation in the human heart.

Verapamil is a commonly prescribed cardiovascular drug, but surprisingly its metabolism in the target tissue of pharmacotherapy is basically unknown. We therefore investigated its biotransformation in human heart tissue and correlate the production of metabolites with the gene expression of major drug metabolising enzymes. Using electrospray LC-MS-MS and LC-MS3 experiments, a total of nine metabolites were observed in incubation experiments with verapamil and microsomes isolated from the human heart tissue, and this included a carbinolamine-, N-formyl-, ahemiacetale-, and formate-intermediate of N-demethyl- and O-demethylverapamil.

A method for the in vitro exposure of human cells to environmental and complex gaseous mixtures: application to various types of atmosphere.

The application of in vitro methods to the analysis of the effects of airborne materials is still limited, because there are no generally accepted concepts and technologies for efficiently exposing adherent growing cells to test atmospheres, especially those comprising complex mixtures of gaseous and particulate phases. The introduction of in vitro research into the field of inhalation toxicology offers a unique possibility for using human cells and tissues for pre-screening studies, thus reducing the necessity for animal experiments, and cutting the numbers of animals used in toxicological testing. We therefore developed a novel experimental concept that uses an exposure device based on the cell cultivation system CULTEX (Patent No.

Butanedione monoxime increases the viability and yield of adult cardiomyocytes in primary cultures.

Various protocols for the isolation and cultivation of adult rat cardiomyocytes were compared, and the cytoprotective potential of the reversible myosin ATPase inhibitor butanedione monoxime (BDM) was evaluated based on cell yield, cell vitality, lactate dehydrogenase (LDH) and creatine kinase (CK) release, and the mRNA expression of atrial natriuretic peptide (ANP). Overall, a yield of 11.9 x 10(6)cells with >92% cell vitality was obtained when BDM was added to the isolation and cultivation buffers.

Pulmonary inflammation in rats after intratracheal instillation of quartz, amorphous SiO2, carbon black, and coal dust and the influence of poly-2-vinylpyridine-N-oxide (PVNO).

Effects of poly-2-vinylpyridine-N-oxide (PVNO) were investigated in numerous in vivo and in vitro studies published in the nineteen sixties and seventies. These studies showed that PVNO inhibited development of fibrosis from quartz dust and improved lung clearance of quartz after inhalation exposure. Ameliorating effects of PVNO were observed also for pulmonary damage from colloidal SiO2 and organic substances, and the fibrogenic inflammation caused by carrageenan.

Verapamil drug metabolism studies by automated in-tube solid phase microextraction.

Verapamil is a common calcium antagonist described with antianginal, antihypertensive and antiarrythmic properties. The metabolites of verapamil have also shown pharmacological properties and therefore sample preparation and analysis techniques capable of metabolic screening for verapamil are important. In-tube SPME is a relatively new method integrating sample extraction, concentration and introduction into one single step without the use of organic solvents.

Establishment and characterization of immortal hepatocytes derived from various transgenic mouse lines.

The potential of three genetic changes introduced into mice by the transgenic or knockout technology aimed at immortalizing hepatocytes in vitro and concomitantly preserving their differentiated hepatic functions was analyzed. Six hepatocyte lines were isolated from neonatal and adult transgenic mice expressing either IgEGF (a secretable variant of hEGF) or SV40 T antigen in the liver and from neonatal and adult p53 knockout (KO) mice and have been subcultured >150 times in serum-free, arginine-deficient medium. Only in SV40 T antigen transgenic lines profiles of mRNAs encoding serum proteins, transcription factors, and liver-specific enzymes were similar to those found in livers and primary hepatocytes.

Aroclor 1254 modulates gene expression of nuclear transcription factors: implications for albumin gene transcription and protein synthesis in rat hepatocyte cultures.

Human exposure to polychlorinated biphenyls (PCBs) may lead to increased albumin serum levels, but little is known about the underlying events. Certain PCBs are also ligands for the aryl hydrocarbon receptor (Ahr) and this receptor regulates transcriptional activation of many different genes, including CYP1A1. We tested our hypothesis that expression of certain nuclear transcription factors is altered upon treatment of rat hepatocyte cultures with Aroclor 1254 and we studied the gene expression of albumin and liver-enriched transcription factors simultaneously.

Exposure of human lung cells to native diesel motor exhaust--development of an optimized in vitro test strategy.

To investigate the effects of native diesel motor exhaust on human lung cells in vitro, a new experimental concept was developed using an exposure device on the base of the cell cultivation system CULTEX (Patent No. DE19801763.PCT/EP99/00295) to handle the cells during a 1-h exposure period independent of an incubator and next to an engine test rig.

The role of surfactant in asthma.

Pulmonary surfactant is a unique mixture of lipids and surfactant-specific proteins that covers the entire alveolar surface of the lungs. Surfactant is not restricted to the alveolar compartment; it also reaches terminal conducting airways and is present in upper airway secretions. While the role of surfactant in the alveolar compartment has been intensively elucidated both in health and disease states, the possible role of surfactant in the airways requires further research.

Complement factors C3a and C5a are increased in bronchoalveolar lavage fluid after segmental allergen provocation in subjects with asthma.

Allergic asthma is thought to be the result of an inappropriate specific immune response against common environmental antigens. However, studies of animal asthma models have also linked the innate immune system, in particular complement factors C3a and C5, to murine airway hyperresponsiveness. Because the possible role of these anaphylatoxins in patients with asthma is not understood, we tested the hypothesis that C3a and C5a will increase in the bronchoalveolar lavage (BAL) fluid of patients with asthma after segmental allergen provocation.

Effects of nonfibrous particles on ceramic fiber (RCF1) toxicity in rats.

In previous investigations a reference test sample of prepared ceramic fibers called RCF1 induced lung tumors in a 2-yr inhalation study in rats. It was hypothesized that nonfibrous particles in RCF1 may have played a significant role. The objective of the present study was to compare lung retention and biological effects of another sample of ceramic fibers, called RCF1a, to the original RCF1.

Cross-fostering inhalation toxicity study with HCFC-123 in lactating Sprague-Dawley rats.

A study was performed in Sprague-Dawley rats (Crl:CD BR) to differentiate between effects of hydrofluorocarbon 123 (HCFC-123) on the lactating dam or on the fetus using fostering and cross-fostering of the offspring. Pregnant and/or lactating dams without the pups present were exposed to the test substance (1000 ppm) or clean air by whole-body inhalation for 6 h/day from day 6 to 19 post conceptionem (p.c.