Photocytotoxicity of a cyanine dye with two chromophores toward melanoma and normal cells.

BACKGROUND: Due to high optical absorption, triplet quantum yield and affinity to biological structures bichromophoric cyanine dyes (BCDs) can be considered promising sensitizers for application in photodynamic therapy (PDT). In this work, we report on the study of the BCD photocytotoxicity toward melanoma and normal cells in comparison with that of commercial photosensitizer Photogem®. METHODS: The cytotoxic and phototoxic effects were measured by standard tests of cell viability. The drug uptake was obtained by the flow cytometry and optical absorption techniques. The BCD intracellular distribution was obtained by the fluorescence image microscopy using specific organelle markers. RESULTS: Both drugs demonstrated increased cytotoxicity under irradiation, while in darkness their cytotoxic effect at concentrations lower than 20 µM after 24 h of incubation did not exceed 20%. For 5 h of incubation, BCD photocytotoxicity in relation to melanoma cells reached 100% already at concentrations below 5 µM, while for normal cells the effect did not exceed 70% even for the 20 µM concentration. It is shown that BCD penetrates into the cells and is located predominantly in perinuclear cytoplasmic structures. CONCLUSIONS: The BCD photosensitizing characteristics appear more adequate for application in PDT than that of the actually applied commercial photosensitizer Photogem®. Higher light absorption by BCD in the near IR region and its preferential localization in mitochondria can explain its high photocytotoxicity. GENERAL SIGNIFICANCE: BCD can be considered as a new promising photosensitizer class for cancer PDT.

[Photosensitizing properties of 3,3'-diethylthiacarbocyanine in biological media].

The objective of the study is elucidation of perspectives of 3,3'-diathylcarbocyaine application as a photosensitizer for curing viral infections by photodynamic therapy. Lipid-containing bacteriophage PM-2 of Pseudoalteromonas espejiana was used as a model. The testing was carried out at a special installation modeling photodynamic exposure conditions towards a non-fractionated phage lysate. 3,3'-DECC demonstrated a rapid photo-bleaching when added tothe phage lysate but not to water. The initial rate of PM-2 phage photoinactivation was proportional to the square concentration of the dye in the range of 0.5-9 µmol/L. This confirms a hypothesis that the dimer is the principal photochemically active form of the dye. An improved ability to form dimers was found in the dye in the phage lysate (10-folds better than in the water). The dye formed a stable adduct with the bacteriophage material. This adduct had an extinction maximum at λ(max) = 594 nm and demonstrated the properties of a polymer (sedimentation under a low-speed centrifugation).

[Characteristics of complex formation between monomeric and dimeric bisbenzimidazoles and AT-containing polynucleotide].

Double-stranded DNA is a one of the most important intracellular anticancer agent targets. Disturbance of DNA functions as well as DNA structure lead to disorder of such processes as transcription and/or translation thus inducing tumor cells death. Complex formation between novel dimeric bisbenzimidazole DB(7) and poly(dA-dT) duplex in comparison with known monomeric bisbenzimidazole MB(Ac) was investigated in this study. DB(7)-poly(dA-dT) binding constant was determined by fluorescence spectroscopy using Scatchard plot and it values 1.18 x 10(8) M(-1) that is two orders of magnitude larger than MB(Ac) one (2.06 x 10(6) M(-1)). Thus, from findings mentioned above it could be concluded that the presence of two bisbenzimidazole moieties in the ligand structure significantly increases its affinity to the polynucleotide which motivates the synthesis of new potential anticancer drugs based on dimeric bisbenzimidazoles.

[Role of the medium acidity in the complexes formation of pyropheophorbide a with albumin and lipoproteins].

The spectral characteristics of the photosensitizer pyropheophorbide a (PPP) complexes with its carriers, that is, serum albumin and low density lipoproteins, were investigated in aqueous solutions at pH 7.4 and 5.0. The acidic pH had no effect on the quantitative parameters of PPP binding to lipoproteins but reduces its affinity for albumin. Differential role of acidification in the binding of PPP to biomacromolecules should be considered in the design of PPP-based drugs given that pH is frequently lowered in the sites of the disease.

[Ribosomal repeat in the cell free DNA as a marker for cell death].

We have developed a novel method for in vivo evaluation of cell death in patients with acute and/or chronic heart diseases, which are accompanied by apoptosis or cell necrosis. The method is based on the analysis of cell free DNA (cfDNA) in the blood serum (or plasma). The major parameters assessed in the method include total concentration of serum cfDNA, concentration of serum ribosomal repeat (rDNA), content of rDNA in total cfDNA, as well as factors of cfDNA elimination, such as nuclease activity and anti-DNA antibody. We demonstrated a fivefold increase in the serum cfDNA concentration and a 12-fold enhancement of serum rDNA concentration in patients with acute myocardial infarction compared with healthy individuals. In chronic coronary ischemia the serum cfDNA concentration was similar to that in the disease-free group. However, the content of rDNA in cfDNA was 4.8-fold higher, and the serum rDNA concentration was increased sevenfold. We hypothesize that one reason for accumulation of rDNA within cfDNA might be the previously reported resistance of rDNA to the ds-fragmentation by serum endonucleases. In both acute and chronic coronary disease the nuclease activity in the serum was substantially higher than that in the healthy cohort. Moreover, the titer of anti-DNA antibodies was elevated, with these antibodies being mostly bound to the cfDNA. Thus, the release of rDNA fragments into the blood not only reflects cellular death in the body but also determines the response of the organism to the disease-associated stress.

[The use of a live Salmonella bivalent vaccine for decreasing the circulation of salmonellae in a poultry plant]. / Primenenie zhivoi sal'monelleznoi bivalentnoi vaktsiny dlia snizheniia tsirkuliatsii sal'monell na ptitsefabrike.

S. typhimurium (expressing antigen 09 of S.dublin) recombinant vaccine strain was tested at a large poultry-breeding farm under the conditions of permanent circulation of salmonellae. The oral immunization of laying hens in three administrations with doses of 5 x 10(8), 5 x 10(9) and 5 x 10(9) microbial cells induced an increase in titers of antibodies only to group D salmonellae, while in immunized chickens (each receiving a dose of 3 x 10(8) microbial cells) antibodies to both group B and group D salmonellae were detected. The vaccination of laying hens and chickens produced a protective effect due to the development of immunity and the decrease of Salmonella contamination of eggs laid by immunized hens, thus reducing the risk of infection at incubator stations. Total mortality during the first 3 months of life was essentially lower (p < 0.001) among immunized chickens (4.41 +/- 0.09%) than in the control group of nonimmunized chickens (5.91 +/- 0.10%).

[Plasmids of antibiotic-resistant strains of Salmonella of varying origin, circulating the Saint-Petersburg and Leningrad region]. / Plazmidy antibiotikorezistentnykh shtammov sal'monell razlichnogo proiskhozhdeniia, tsirkuliruiushchikh v Sankt-Peterburge i Leningradskoi oblasti.

Two hundred and twenty Salmonella strains of various serovars isolated from different source in St. Petersburg and the Leningrad Region in 1984-1991 were investigated. It was shown that drug resistance in 39.3 per cent of the strains was determined by conjugative R plasmids with the molecular weights of 28 to 90 mD which transferred at a rate of 10(-4) to 10(-8). Thirteen detected types of the Salmonella conjugative R plasmids differing in the resistance markers, molecular weights and conjugative transfer rates most frequently contained the genes responsible for the resistance to tetracycline (97.7 per cent), chloramphenicol (92.0 per cent), streptomycin (83.0 per cent), kanamycin (76.1 per cent), monomycin (76.1 per cent) and neomycin (76.1 per cent). The conjugative R plasmids were mainly detected in S> typhimurium (92.9 per cent), especially in the isolates from humans (97.6 per cent). The most frequent plasmid type in the Salmonella strains of this serovar was that with the molecular weight of 90 mD carrying the genes of resistance to chloramphenicol, tetracycline, streptomycin, kanamycin, monomycin and neomycin.

[Sensitivity to antibacterial drugs of Salmonella isolated from various sources in Saint-Petersburg and Leningrad region]. / Chuvstvitel'nost' k antibakterial'nym preparatam sal'monell, vydelennykh iz razlichnykh istochnikov v Sankt-Peterburge i Leningradskoi oblasti.

The position of antibiotic resistant cultures among 1706 strains of 85 Salmonella serovars isolated from various sources in St. Petersburg and the Leningrad Region in 1984-1991 amounted to 16.4 per cent. The highest position of such cultures was among the isolates from humans (20.9 per cent). The positions of the isolates from animals, birds and environment were practically equal (13.8, 13.8 and 13.7 per cent respectively). Strains resistant to streptomycin (11.9 per cent), tetracycline (11.5 per cent) and chloramphenicol (11.2 per cent) were the most frequent Salmonella isolates from the different sources. Rifampicin, amikacin, thienamycin, nitroxolin, oxolinic acid, dioxidin, ciprofloxacin and pefloxacin proved to be highly active against the isolates. No significant difference in the antibiotic resistance spectra of the Salmonella strains circulating in different biotopes was detected. However, among the Salmonella isolates from humans there undoubtedly predominated polyresistant strains with the resistance spectra including 10 and 6 antibacterial drugs (42.4 and 28.8 per cent of the resistant strains respectively). Sometimes there was observed correlation between the serovars of the Salmonella strains (independent of the isolation source) and the most characteristic spectra of their antibiotic resistance. Thus, the antibiotic resistant spectra of 79 per cent of the S. typhimurium strains and 82.5 per cent of the S. haifa strains resistant to one and more antibacterial drugs were the following: CmTcSmKmMmNm and ApCbCmTcSmKmMmNmGmNal respectively.

[Isolation of purified Ebola virus]. / Poluchenie ochishchennogo virusa ébola.

Purified concentrates of Ebola virus were prepared by two methods, adsorption on polyethylenglycol-600 followed by ultracentrifugation in sucrose density gradient and ultrafiltration. The ultrafiltration method permits preparation of concentrated Ebola virus with better preserved virion structure and infective activity than the traditional method.

[Protection from virulent Salmonella groups B and D after the peroral immunization of chicks with a hybrid of Salmonella typhimurium and Salmonella dublin]. / Zashchita ot virulentnykh sal'monell grupp B i D posle peroral'noi immunizatsii tsypliat gibridom Salmonella typhimurium i Salmonella dublin.

Chickens over 10 days old, infected orally with virulent salmonellae, were found to remain alive. Histologic investigation showed the development of mild enteritis and more pronounced, lasting for more than two weeks, inflammation of the cecum, dissemination and focal lesions in the liver (granulomas, necrosis). In experiments on the oral immunization of 3-day old chickens the bivalent hybrid of S. typhimurium vaccine strain 274 and S. dublin induced only pronounced blast transformation in lymphatic follicles of the cecum, hyperplasia of activated macrophages and formation of granulomas from these macrophages and lymphocytes. After oral challenge of the immunized chickens with virulent salmonellae of group B (S. typhimurium) and group D (S. enteritidis, S. gallinarum-pullorum) the chickens exhibited sharply pronounced protection against adhesion, colonization and invasion, and a few penetrating bacteria were rapidly destroyed by immune macrophages. Hybrid strain 274/O9 proved to be suitable for use as oral bivalent vaccine against salmonellosis in chickens.

[The immunogenic properties of Marburg virus proteins]. / Immunogennye svoistva belkov virusa Marburg.

Immunogenic and protective properties of VP40 and NP proteins of Marburg virus were studied. VP40 protein was shown to have insignificant immunogenicity and NP protein to be capable of protecting the animals from lethal infection by stimulation of cell-mediated immunity. No significant increase in the specific antibody level was found.

[A comparative study of the immunological indices in guinea pigs administered an inactivated Marburg virus]. / Sravnitel'noe izuchenie nekotorykh immunologicheskikh pokazatelei pri vvedenii inaktivirovannogo virusa Marburg morskim svinkam.

Samples of concentrated and unconcentrated preparations of Marburg virus were studied. The ultrafiltration method helped increase the specific protein content and decrease the common protein content in a preparation. The resistance index increased with an increase of the specific protein content and the maximum (2.63 +/- 0.2) was reached by two immunizations on 0 and 14 days.