Relationship between dimedone concentration and formaldehyde captured in plant tissues.

In different parts of water-melon plants (Citrullus vulgaris L.) formaldehyde (HCHO), in dimedone adduct form (formaldemethone), and fully N-methylated substances were identified and determined by OPLC as well as HPLC, capillary GC and GC-MS methods using authentic substances. The HCHO captured originates from dynamic methylation and demethylation processes in which this simplest aliphatic aldehyde is bound in the form of highly reactive hydroxymethyl groups. Dimedone will react with the small quantity of HCHO in equilibrium with the hydroxymethyl groups and it follows from this that the rate of HCHO captured as the dimedone adduct will increase parallel to the increasing concentration of dimedone applied, as a methanolic solution, until a plateau is reached. The level of HCHO was very high in the roots of water-melon seedlings.

Drought stress, peroxidase activity and formaldehyde metabolism in bean plants.

In our investigations we have studied the changes of total peroxidase and isozyme activities, peroxidase isozyme pattern and the level of endogenous formaldehyde and trigonelline. We have examined the effect of drought stress resulted by Carbowax treatment (2, 5, 7, 10%) of two different snap bean (Phaseolus vulgaris L.) genotypes [drought tolerant (T) and drought sensitive (S)]. There were no detectable differences in the peroxidase isozyme patterns but the total peroxidase activity was increased. We have found similar steep enhancement in the peroxidase activities of one of three peroxidase fractions while the increase in the other isozyme fractions was not so significant in the two genotypes. Increasing peroxidase activities and changes in the amount of endogenous formaldehyde and trigonelline were detectable with increasing Carbowax treatment in both genotypes, but in different ways. According to our experiments, the total peroxidase and some isozyme activity correlated with the concentration of endogenous formaldehyde and trigonelline, playing an important role during drought stress.

Change of biotransformation steps of formaldehyde cycle in water-melon plants after infection with Fusarium oxysporum.

Recent experiments indicate that the measurable formaldehyde (HCHO) level is considerably elevated in the parts of water-melon plants immediately after a nonlethal infection with Fusarium oxysporum f. sp. niveum. At the same time the level of some quaternary ammonium compounds (N(epsilon)-trimethyl-L-lysine, choline) as potential HCHO generators (gene products) is considerably decreased. That is probably due to the fact that the alarm reaction phase of this biotic stress syndrome includes an intensive demethylation process. It has been proved that HCHO may play a role in dynamic methylation-demethylation processes that also may include the methylation of biotic stress proteins. In this paper we report on qualitative and quantitative changes in the biotransformation steps of the formaldehyde cycle in different parts of the water-melon plant after nonlethal infection (biotic stress) with Fusarium. In consequence of the infection identical quantitative changes, but to a different degree, of the compounds examined are observable in both varieties. The connections resulting from the depiction of the time-dependent quantitative changes of the measured methylated compounds due to infection show a picture similar to that of Selye's stress syndrome model.

Investigation of some methylated compounds and peroxidase activity during plant ontogenesis in snap bean.

Changes in the level of endogenous formaldehyde (HCHO) and some N-methylated compounds were investigated in the leaves of snap bean (Phaseolus vulgaris L.) during ontogenesis. In addition, the activity and isozyme pattern of peroxidase enzymes were also examined. HCHO, as dimedone adduct, and fully N-methylated compounds were determined by overpressured layer chromatography in different development stages of snap bean plant. Peroxidase activities were measured by spectrophotometry and isozyme patterns were examined by isoelectric focusing. HCHO level decreased until blooming with aging of the plant being the highest in the youngest leaves all the time, but then increased again in old leaf tissues. At the same time the concentration of choline and trigonelline as potential HCHO generators (marker molecules or gene products) decreased considerably while peroxidase activity increased with aging of plants.

Simple determination of formaldehyde in dimedone adduct form in biological samples by high performance liquid chromatography.

A high performance liquid chromatographic method for the determination of endogenous formaldehyde in dimedone adduct form in biological samples is described. The simple procedure involves extraction of the formaldehyde of different binding force in biological samples with methanol containing dimedone as the capture molecule and separation on a C18 reversed phase column with methanol as eluent.

Possibility of formation of excited formaldehyde and singlet oxygen in biotic and abiotic stress situations.

The results obtained prove that singlet oxygen and excited formaldehyde can be liberated from hydrogen peroxide and formaldehyde in free and bound L-lysine containing plant and other tissues, similarly to the model reactions. It can be concluded that these reactive molecules have extremely high reactivity and are possibly aggressive to cellular components like proteins, nucleic acids and to microbial systems within plant and other tissues. However, the manifestation of their activity depends on level of quenching systems in plant and other tissues. It seems that these special reactions and their products may be an important part of the resistance potential (e.g. natural disease resistance) in biological systems.

In vitro protein binding behavior of dipyridamole.

The in vitro protein binding behavior of dipyridamole in plasma and buffered protein solutions was investigated by equilibrium dialysis. The drug was highly protein bound (approximately 98%) in heparinized human plasma, and the extent of protein binding remained constant for drug concentrations over the range of therapeutic interest of 0.1-10 micrograms/mL. Comparable binding results were obtained with a mixture of 80 mg % of alpha 1-acid glycoprotein and 40 g/L of human serum albumin in pH 7.4 phosphate buffer solution. Pure alpha 1-acid glycoprotein (80-400 mg %) or pure human serum albumin (40 g/L) in phosphate buffer gave significantly (p less than 0.05) lower binding results, indicating that both proteins are responsible for the high binding of dipyridamole in plasma. Addition of alpha 1-acid glycoprotein to heparinized human plasma, to simulate an acute phase increase in the protein, had no effect on the fraction of free drug in plasma. Binding of dipyridamole to heparinized human plasma or human serum albumin in buffer was concentration independent through 40 micrograms/mL. The free fraction of dipyridamole increases with concentrations exceeding 40 micrograms/mL.

A case of methimazole-induced hypothyroidism in a patient with endemic goiter: effects of endogenous TSH hyperstimulation after discontinuation of the drug.

Serum thyroid hormone and TSH concentrations were monitored in a patient with multinodular endemic goiter and severe methimazole (MMI) induced hypothyrodism up to 190 days after drug withdrawal. Serum concentrations of TT3, TT4 and TSH returned to normal values at the 6th., the 140th, and the 120th. day respectively. Within the first 20 days after MMI withdrawal the increase of serum T3 levels was correlated with the observed decrease of serum TSH concentrations. Successively T3 values decreased and T4 levels progressively increased. Six months after MMI withdrawal basal serum TSH concentration was normal while an exaggerated response to TRH was observed. We think that this peculiar hormone pattern is due to iodine depletion. In this case TSH hyperstimulation increases predominantly T3 secretion demonstrating the reduced thyroidal ability to produce T4 when hyperstimulated.

[Mitral valve and left ventricular function in ostium secundum type interatrial communication, studied by left ventriculography]. / Estudio de la válvula mitral y de la función ventricular izquierda en la comunicación interauricular tipo ostium secundum por medio de la ventriculografía izquierda.

Clinical, hemodynamic and cineangiographic studies were performed in 11 patients with atrial septal defect (ASD) of ostium secundum type. Mitral valve prolapse was found cineangiographically in 9 cases. Systolic and diastolic left ventricular volumes were significantly increased, while left ventricular function and compliance were normal. A careful systematic exploration of mitral valve in patients with ASD ostium secundum seems to be advisable.