Photochemical Properties of Camptothecin in the Presence of Copper(II) Ions: The Role of Radicals as Prospective Species in Photodynamic Therapy

Camptothecin (CPT) is an anticancer drug that inhibits topoisomerase I (Topo I) by forming a ternary DNA-CPT-Topo I complex. However, it has also been shown that UVA-irradiated CPT in the absence of Topo I produces significant DNA damage to cancer cells. In this work, we explored and identified free radicals generated in these processes. From the low-temperature EPR spectrum of Cu(II)-CPT complex, a proximity between Cu(II) ion and 20-hydroxy group of lactone E ring of CPT is proposed. Upon irradiation (λ = 365 nm) of the Cu(II)-CPT complex in de-oxygenated dimethylsulfoxide (DMSO), the EPR signal of Cu(II) measured in situ at room temperature shows formal first-order exponential decay with a formal half-life of 11 min. By the use of a specific Cu(I) chelating agent, neocuproine, it was shown that, during this process, Cu(II) is reduced to Cu(I). The loss in EPR signal intensity of the Cu(II)-CPT complex upon irradiation is accompanied by the appearance of a new EPR signal at g ≈ 2.0022. Application of the spin trap nitrosodurene (ND) revealed that the main radical product formed upon continuous irradiation of CPT in DMSO solutions is the hydroxyl radical (trapped in DMSO as the ^•CH₃ adduct) and superoxide radical. Application of 2,2,6,6-tetramethyl-4-piperidinol has revealed that irradiation of CPT in aerated DMSO solution also leads to formation of singlet oxygen (¹O₂). Our spectroscopic experiments indicate that CPT is a promising photosensitizer and that radicals and singlet oxygen generated upon illumination play a central role in DNA cleavage and in the induction of apoptosis in cancer cells.     

Filamentous organisms in activated sludge

Activated sludge, as an aerobic environment rich in organic matter, often provides the optimum conditions for the development of colourless filaments. From the taxonomic point of view, these colourless filaments can be divided into three groups of basic characteristics: bacteria, cyanophyceae and fungi. The effort to distinguish these three groups is not only inspired by the endeavour to classify them taxonomically correctly, but rather by possible different physiological efficiencies of the individual groups. This may be their basic significance for the determination of technical parameters of the activated sludge process.     

Pollen analysis of dust preserved in four medieval books

Pollen spectra of three samples of dust taken from four medieval books are reported. The books, printed A.D. 1500–1530, were preserved in the Franciscan monastery of Kadaň (NW Bohemia) up to c. 30 years ago, and thereafter in Prague. Sample 1 contains rather few pollen grains, most of which are derived from cereals, probably from pastries or bread. Sample 2 is rich in pollen, containing abundant tree pollen, mainlyQuercus andFagus, indicating that the dust indeed comes from NW Bohemia rather than from Prague. Its overall pollen spectrum also corresponds well to published data from medieval forests and the cultural landscape of the region. The spectrum of sample 3 (two books) is rather rich in pollen, mainly of synanthropic plants. The remarkably high pollen numbers of cultivated plants (Sambucus nigra, Lathyrus type andSymphytum) are still unexplained.     

Palaeoecology of a medieval fishpond system (Vajgar, Czech Republic)

A palaeoecological investigation of a sediment core obtained from an artificial lake — the fishpond Vajgar (40 ha) near the town of Jind?ich?v Hradec, southern Bohemia, has been carried out in connection with extensive multidisciplinary research preceding the removal of its sediment. Samples from selected standard profile were subjected to chemical, pollen, and palaeoalgological analyses in order to study the chronology of vegetation development, anthropogenic impact on the landscape, and the development of an artificial fishpond ecosystem. The palaeoecological record under study comprises the period of extensive change from pre-cultural, silver fir-dominated forest vegetation into managed, agricultural landscape dominated by cereal fields and pastures. After Medieval colonization, the proportion between wooded and open landscape changed, and the composition of original forests shifted to pine. Pollen spectra from the High Middle Ages are characterized by high percentages of anthropogenic indicators and closely resemble the results from urban deposits (cesspits, wells, communication horizons, etc.). This period can be subdivided into a first phase correlated with the High and Late Middle Ages and a second phase correlated with the post Medieval period and partly maybe also with the agricultural collectivization of the 20th century. The earlier phase has a rather uniform character with a significant presence of grazing indicators and cereal weeds. After the collectivization of the 1950s and later, a substantial change in agricultural practices can be detected: the large-scale use of herbicides affecting the composition of agricultural ruderal species (e.g. decline of cornflower (Centaurea cyanus), rye (Secale), etc.). The development of the aquatic system of the fishpond Vajgar was studied by means of chemical and palaeoalgological analyses. On the basis of observed changes in the composition of subfossil algal communities, the fishpond history can be split into four distinct phases. It is assumed that the progression over individual phases was caused by changes in water chemistry that can be interpreted as shifts in water quality caused by the urbanization of the surrounding areas as well as by changes in agricultural practices. The results of the investigation of some chemical elements (especially heavy metals) show stratigraphic patterns that can be related to historical events. These results show that the mixing and bioturbation of the sediment was not so significant as might be expected.     

Lenticulostriatal vasculopathy - a marker for congenital cytomegalovirus infection?

Lenticulostriate vasculopathy (LSV) is an ultrasound (US) visible lesion of the brain, which appears as echogenic streaks or spots in the arteries of thalamus and basal ganglia. LSV has varied etiology. Transfontanelar Color Doppler (TFCD) can easily display lenticulostriatal blood flow and assess: stage I LSV with present flow within echogenic changes and stage II LSV in which the flow disappears, despite a presence of streaks and spots, which at this stage most probably correspond to calcification. The objectives of this study are to determine: (1) Whether there are differences in distribution (unilateral or bilateral) and presence (during first year of age) of TFCD flow between congenital CMV infection positive and negative group of children with LSV (2) Could US and TFCD findings of LSV be an indication for further investigation of possible congenital CMV infection, because of their variable and often adverse neurodevelopmental outcome? We examined and followed-up 98 infants with LSV One group (37/98) with congenital CMV infection and second (61/98) negative. All infants had clinical signs of neuromotor delay and ultrasound and TFCD markers of LSV Our study shows that most of the patients from both groups had TFCD visible flow at the age of 0-4 months. In majority of them in both groups, at the age of 5-8 months, there was no more visible flow. TFCD showed no statistically significant difference among congenital CMV infection positive group and negative group, nor in youngest age period (0-4 months), nor in later course of flow in LSV unilaterally or bilaterally. Although the LSV presents nonspecific marker for intracranial infection (ICI), all infants presenting with LSV should be evaluated for possible ICI. Thus, the Doppler findings of LSV in infants require a detailed examination, monitoring and follow-up of neuromotor outcome.