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Biomedical subjects

V Sýkora

Publications and source records attributed to V Sýkora.

10 recordsLinked to original sources
PubMed2001

Biodegradability of ethylenediamine-based complexing agents.

Biological degradability of ethylenediamine derivatives depends on the type and number of substituents. The susceptibility to biodegradation decreases in the sequence of substituents -COCH3, -CH3, -C2H5, -CH2CH2OH, -CH2COOH and with polysubstitution. The biodegradability depends also on the kind and number of nitrogen atoms. Complexing agents with a single-nitrogen atom in the molecule (e.g. NTA) succumb relatively readily to biodegradation whereas, compounds with two or more tertiary amino groups are biologically highly stable and do not undergo biodegradation even in experiments with activated sludge adapted at an age of up to 30 days (EDTA, DTPA, PDTA, HEDTA). A lowering of the degree of substitution brings about an increased susceptibility to biodegradation. This holds, e.g., for replacement of tertiary amino groups with secondary ones; thus the symmetrically disubstituted ethylenediamine-N,N'-diacetic acid (EDDA) possesses still sufficient complexing ability while belonging already to the group of potentially degradable substances.

Biodegradation, Environmental↗
PubMed2001

Biodegradability of ethylenediamine-based complexing agents and related compounds.

The biological degradability (Zahn-Wellens test) of ethylenediamine derivatives with carboxymethyl and 2-hydroxyethyl groups was investigated. Mixed bacterial culture (activated sludge) was used as inoculum (non-adapted sludge and sludge adapted at different mean biomass retention time, the so-called sludge age). Biodegradability of ethylene(propylene)di(tri)amine-based complexing agents depends on the character and number of substituents and nitrogen atoms in the molecule. Tetra(penta)substituted derivatives with two or more tertiary nitrogen atoms and carboxymethyl or 2-hydroxyethyl groups in the molecule (EDTA, DTPA, PDTA, HEDTA) are very stable from an environmental point of view. On the contrary, disubstituted derivatives with two secondary nitrogen atoms in the molecule (e.g., EDDA) are potentially degradable.

Bacteria↗
PubMed1994

Hairlessness does not influence growth retardation in nude mice. Computer image analysis study.

Ossification in 4-week-old nu/nu and nu/+ BALB/c and BFU mice was studied by X-ray analysis and by measurement of the thickness of the proximal tibial growth cartilage using CUE 4 Olympus computer image analysis. Not only altered architecture but also a significantly thinner proximal tibial growth plate was observed in athymic nu/nu as opposed to nu/+ and BFU mice. On the other hand, no significant differences were found between nu/+ and BFU littermates. Higher X-ray density of tail vertebrae was observed in nu/+ and BFU than in nu/nu mice. This comparison between athymic nu/nu and hairless euthymic BFU mice indicates that altered postnatal ossification in nude mice is not caused by hairlessness, but is due to other (immunological or endocrinological) differences.

Animals↗
PubMed1993

Development of the cellular response in the mouse omentum after intraperitoneal immunization.

Using computer image analysis we studied the development of dense cellular and dense lymphoid areas ("milky spots") and of pendant lymphatic nodules in mouse omenta after intraperitoneal immunization with sheep red blood cells. In both euthymic (BALB/c and hairless BFU) and athymic hairless nu/nu BALB/c mice the proportion of newly developing activated omental areas (AOA) was biphasic, with distinct peaks on days 3-4 and 8-12 after immunization, and a trough on days 5 and 14. There was a small difference between athymic and euthymic BALB/c mice. In comparison with the nu/nu BALB/c mouse, the BFU mutant had a lower proportion of AOA on days 4 and 10. The athymic state is not thought to have a great influence on the AOA development; this depends on a basic macrophage defence, which is well developed in the athymic model, and is self-regulated and shaped by a sequence of cell immigration, settling, differentiation and emigration.

Animals↗