The role of free radicals in canine counterpart of senile dementia of the Alzheimer type.

The pathogenesis of Alzheimer's disease is still unknown. In recent time oxidative stress has been discussed as an important contributor. In the present study we investigated the role of free radicals in the spontaneous canine model of Alzheimer's disease. We analysed end-products of lipid peroxidation: lipofuscin-like pigments (LFP), protein carbonyls, and vitamin E to obtain data on oxidative damage in brain of demented dogs. When the generation of free radicals is intensive the toxic products of lipid peroxidation can diffuse from the site of the primary formation and merge with erythrocytes. Therefore we also determined the level of lipid peroxidation in red blood cells. In brain of demented animals the level of LFP increased (to 247%, P<0.05) as well as of protein carbonyls (to 438%, P<0.01) while the vitamin E concentration was lowered (to 34%, P<0.01) when compared to age-matched non-demented controls. The end-products of lipid peroxidation have been found increased also in erythrocytes of demented dogs (250%, P<0.05). These results indicate intensive production of free radicals in brain of animals with dementia which induces damage to erythrocytes. Detection of the specific products of free radical damage in blood samples could be used for diagnostic purposes.

[Interesting urinary findings in acute intermittent porphyria]. / Zajímavý mocový nález u akutní intermitentní porfyrie.

The authors describe an uncommon case of a patient with acute intermittent porphyria whose urine on standing, when exposed to light and air, turned dark and eventually black. The reason was increased excretion of porphobilin. The urine continued moreover increased amounts of Thormählen-positive substances, typical melanogens were not detected, however. The authors wish to draw attention to possible diagnostic errors which arise due to erroneous interpretation of laboratory results.

[Synthesis of eumelanin pigment precursors. II. 6-hydroxy-5-methoxy- and 5-hydroxy-6- methoxyindole]. / Syntéza prekurzoru pigmentu eumelaninu. II. 6-hydroxy-5-methoxy- a 5-hydroxy-6-methoxyindol.

Following up of specific melanogenesis metabolite excretion in the course of malignant melanoma disease is useful for the disease prognosis assessment. The authors elaborated a modified synthesis technique of 6-hydroxy-5-methoxy and 5-hydroxy-6-methoxyindole, eumelanin pigment precursors. The elaborated synthesis is economically and temporally reasonable and the synthesized compounds accord, as proved by means of elementary analysis, thin layer (TLC) and high performance liquid chromatography (HPLC) and last but not least by nuclear magnetic resonance (NMR), with demands for reference compounds needed for isomer hydroxymethoxyindole quantification in urine.

[Synthesis of eumelanin pigment precursors. II. 6-Hydroxy-5-methoxy- and 5-hydroxy-6-methoxyindol]. / Syntéza prekurzoru pigmentu eumelaninu. II. 6-Hydroxy-5-methoxy-a 5-hydroxy-6-methoxyindol.

Following up of specific melanogenesis metabolite excretion in the course of malignant melanoma disease is useful for the disease prognosis assessment. The authors elaborated a modified synthesis technique of 6-hydroxy-5-methoxy and 5-hydroxy-6-methoxyindole, eumelanin pigment precursors. The elaborated synthesis is economically and temporally reasonable and the synthesized compounds accord, as proved by means of elementary analysis, thin layer (TLC) and high performance liquid chromatography (HPLC) and last but not least by nuclear magnetic resonance (NMR), with demands for reference compounds needed for isomer hydroxymethoxyindole quantification in urine.

Identification of two Thormählen-positive compounds from melanotic urine by gas chromatography-mass spectrometry.

The isolation of two Thormählen-positive compounds from the urine of a patient with malignant melanoma and the elucidation of their structure by gas chromatography-mass spectometry is described. The compounds were isolated using a poly-N-vinylpyrrolidone column and separated by preparative thin-layer chromatography. After elution they were analyzed by gas chromatography and gas chromatography-mass spectrometry as their trimethylsilyl derivatives and after hydrolysis also as their tert.-butyldimethylsilyl derivatives. The results showed the main Thormählen-positive compound A to be the glucuronide of 5-hydroxy-6-methoxyindole, whereas the minor compound AX appeared to be the glucuronide of its isomer 6-hydroxy-5-methoxyindole.