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Biomedical subjects

R Hodr

Publications and source records attributed to R Hodr.

At least 37 records · Page 2Linked to original sources
PubMed1986

Kinetics of the formation of biliverdin during the photochemical oxidation of bilirubin monitored by column liquid chromatography.

In the photochemical oxidation of bilirubin, biliverdin is formed as the primary product and is further degraded. This photooxidation is especially significant in the presence of riboflavin. Column liquid chromatography was used to monitor the kinetics of this reaction. The biliverdin concentration amounts to a maximum of ca. 38% of the total loss of bilirubin in experiments in vitro. It is probable that this mechanism is also operative during phototherapy. The formation of a product of the photooxidation of biliverdin that has not yet been identified has been observed; the product behaves as a dimer. A method for the determination of biliverdin in the blood of newborn infants has been developed. It has been found that the biliverdin content increases during hyperbilirubinaemia.

Bilirubin↗
PubMed1984

Reversible photoreduction of flavin with bilirubin II.

Bilirubin react with flavins under both aerobic and anaerobic conditions. Under anaerobic conditions these substances behave as a redox-system in solution, riboflavin functioning as an electron acceptor and bilirubin as an electron donor. The reaction products are the leuco-form of riboflavin and biliverdin. On the basis of the dependence of the optical spectrum and of the reaction rate on pH it can be assumed that bilirubin reacts in the anionic form. Under anaerobic conditions a reversible reaction occurs leading to a dynamic equilibrium of the reactants. The products were identified and determined by optical spectroscopy, chromatography and potentiometry. Excretion of biliverdin in the stool of new-born infants was orientatively monitored during the phototherapy of hyperbilirubinemia, after the administration of small doses of riboflavin. It has been found that excretion of biliverdin increases during the phototherapy. The possibility of utilizing the described reaction for an improvement in the phototherapy of new-born infant hyperbilirubinemia is discussed.

Bilirubin↗
PubMed1981

Reversible photoreduction of flavin with bilirubin I.

In the photochemical degradation of bilirubin under anaerobic condition, the bilirubin riboflavin-system behaves as an equilibrium electrochemical system characterized by a redox-potential. Bilirubin decomposes irreversibly and riboflavin functions as a reversible electron acceptor. This equilibrium is not established under aerobic conditions, probably due to reoxidation of the riboflavin leuco-form by oxygen. Riboflavin accelerates the bilirubin photodegradation about 30 times at equimolar concentrations of the two components and in the presence of a buffer at pH 7.3. The present results of a study on a model system are applicable in the phototherapy of newborn infant hyperbilirubinemia.

Aerobiosis↗
PubMed1980

The suppressive effect of continuous infusion of bilirubin on the immune response in mice.

Mice (strains Balb/c and A/J) received an intravenous infusion of bilirubin for a 1 d period. The infusion was delivered at various phases of the primary reaction; the degree of the immune response was expressed as the number of antibody-forming cells against sheep erythrocytes. Bilirubin infusion during both the inductive and productive phase of the primary reaction decreased significantly the immune response. We assume that bilirubin influences the differentiation of immunocompetent cells immediately after their contact with the antigen; in addition it acts in the period of the quantitative increase of the number of antibody-producing cells.

Animals↗
PubMed1980

Effect of bilirubin and its photodegradation products on the respiration of mitochondria isolated from rat liver.

In 0.05--0.1 mmol.l-1 concentration, bilirubin inhibits ADP-activated respiration of isolated liver mitochondria; it has no effect on respiration in the absence of ADP. Bilirubin-induced inhibition of respiration is not abolished by serum albumin, but bilirubin bound to serum albumin and the photodegradation products of bilirubin have no inhibitory effect.

Adenosine Diphosphate↗