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Biomedical subjects

M Vondracek

Publications and source records attributed to M Vondracek.

6 recordsLinked to original sources
PubMed2004

Alcohol dehydrogenase 3 transcription associates with proliferation of human oral keratinocytes.

Gene expression underlying cellular growth and differentiation is only partly understood. This study analyzed transcript levels of the formaldehyde-metabolizing enzyme alcohol dehydrogenase 3 (ADH3) and various growth and differentiation-related genes in human oral keratinocytes. Culture of confluent cells both with and without fetal bovine serum inhibited colony-forming efficiency and induced a squamous morphology. Confluency alone decreased the transcript levels of ADH3, the proliferation markers cell division cycle 2 (CDC2) and proliferating cell nuclear antigen (PCNA), and the basal cell marker cytokeratin 5 (K5), but increased transcripts for the suprabasal differentiation markers involucrin (INV) and small proline-rich protein 1B (SPR1). These changes were variably influenced by serum, i.e., loss of CDC2 and PCNA was inhibited, loss of K5 promoted, increase of SPR1 transcripts inhibited, and increase of INV promoted. The extent and onset of the effects implied that ADH3 transcription serves as a proliferation marker and that confluency with or without serum exposure can serve to selectively analyze proliferative and differentiated cellular states.

Aldehyde Oxidoreductases↗
PubMed2001

Reproducible gene expression measurement among multiple laboratories obtained in a blinded study using standardized RT (StaRT)-PCR.

BACKGROUND: A method that provides standardized data and is relatively inexpensive and capable of high throughput is a prerequisite to the development of a meaningful gene expression database suitable for conducting multi-institutional clinical studies based on expression measurement. Standardized RT (StaRT)-PCR has all these characteristics. In addition, the method must be reproducible. StaRT-PCR has high intralaboratory reproducibility. The purpose of this study is to determine whether StaRT-PCR provides similar interlaboratory reproducibility. METHODS AND RESULTS: In a blinded interlaboratory study, expression of ten genes was measured by StaRT-PCR in a complementary DNA sample provided to each of four laboratories. The average coefficient of variation for interlaboratory comparison of the nine quantifiable genes was 0.48. In all laboratories, expression of one of the genes was too low to be measured. CONCLUSION: Because StaRT-PCR data are standardized and numerical and the method is reproducible among multiple laboratories, it will allow development of a meaningful gene expression database.

Binding, Competitive↗
PubMed2001

Micro-array chip analysis of carbonyl-metabolising enzymes in normal, immortalised and malignant human oral keratinocytes.

Enzymes involved in various protective and metabolic processes of carbonyl compounds were analysed utilising a micro-array method in a three-stage in vitro model for oral carcinogenesis involving cultured normal, immortalised and malignant human oral keratinocytes. A complete transcript profiling of identified carbonyl-metabolising enzymes belonging to the ADH, ALDH, SDR and AKR families is presented. Expression of 17 transcripts was detected in normal, 14 in immortalized and 19 in malignant keratinocytes of a total of 12,500 genes spotted on the micro-array chip. For the detected transcripts, about half were changed by cell transformation, and for the various enzyme families, differences in expression patterns were observed. The detected AKR transcripts displayed a conserved pattern of expression, indicating a requirement for the keratinocyte phenotype, while most of the detected SDRs displayed changed expression at the various stages of malignancy. The importance of multiple experiments in using a microarray technique for reliable results is underlined and, finally, the strength of the method in detecting co-expressed enzymes in metabolic pathways is exemplified by the detection of the formaldehyde-scavenging pathway enzymes and the polyol pathway enzymes.

Alcohol Dehydrogenase↗
PubMed2001

Cytochrome P450 expression and related metabolism in human buccal mucosa.

Constituents in food and fluids, tobacco chemicals and many drugs are candidates for oral absorption and oxidative metabolism. On this basis, the expression of cytochrome P450 isozymes (CYPs) and the conversion of CYP substrates were analysed in reference to buccal mucosa. A RT-PCR based analysis of human buccal tissue from 13 individuals demonstrated consistent expression of mRNA for the CYPs 1A1, 1A2, 2C, 2E1, 3A4/7 and 3A5. CYP 2D6 was expressed in six out of the 13 specimens, whereas all samples were negative for 2A6 and 2B6. Serum-free monolayer cultures of the Siman virus 40 large T-antigen-immortalized SVpgC2a and the carcinoma SqCC/Y1 buccal keratinocyte lines expressed the same CYPs as tissue except 3A4/7 and 3A5 (SVpgC2a), and 2C, 2D6 and 3A4/7 (SqCC/Y1). Dealkylation of ethoxyresorufin and methoxyresorufin in both normal and transformed cells indicated functional 1A1 and 1A2, respectively. SVpgC2a showed similar activity as normal keratinocytes for both substrates, whereas SqCC/Y1 showed about 2-fold lower 7-ethoxyresorufin O-deethylation and 7-methoxyresorufin O-demethylation activities. SVpgC2a showed detectable and many-fold higher activity than the other cell types towards chlorzoxazone, a substrate for 2E1. Absent or minute catalytic activity of 2C9, 2D6 and 3A4 in the various cell types was indicated by lack of detectable diclofenac, dextromethorphan and testosterone metabolism (<0.2-0.5 pmol/min/mg). Metabolic activation of the tobacco-specific N-nitrosamine 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and the mycotoxin aflatoxin B1 (AFB1) to covalently bound adducts was indicated by autoradiographic analysis of both monolayer and organotypic cultures of SVpgC2a. In contrast, SqCC/Y1 showed lower or absent metabolic activity for these substrates. Finally, measurements of various non-reactive AFB1 metabolites indicated rates of formation <0.1 pmol/min/mg in both normal and transformed cells. The results indicate presence of several CYPs of which some may contribute to significant xenobiotic metabolism in human buccal epithelium. Notably, metabolic activation of AFB1 was not previously implicated for oral mucosa. Further, the results show that CYP-dependent metabolism can be preserved or even activated in immortalized keratinocytes. Metabolic activity in SVpgC2a under both monolayer and organotypic culture conditions suggests that this cell line may be useful to pharmaco-toxicological and carcinogenesis studies.

Aflatoxin B1↗
PubMed1995

HOROPLAN: computer-assisted nurse scheduling using constraint-based programming.

Nurse scheduling is a difficult and time consuming task. The schedule has to determine the day to day shift assignments of each nurse for a specified period of time in a way that satisfies the given requirements as much as possible, taking into account the wishes of nurses as closely as possible. This paper presents a constraint-based, artificial intelligence approach by describing a prototype implementation developed with the Charme language and the first results of its use in the Rouen University Hospital. Horoplan implements a non-cyclical constraint-based scheduling, using some heuristics. Four levels of constraints were defined to give a maximum of flexibility: French level (e.g. number of worked hours in a year), hospital level (e.g. specific day-off), department level (e.g. specific shift) and care unit level (e.g. specific pattern for week-ends). Some constraints must always be verified and can not be overruled and some constraints can be overruled at a certain cost. Rescheduling is possible at any time specially in case of an unscheduled absence.

France↗