Dicle Guc

Designing excited states: theory-guided access to efficient photosensitizers for photodynamic action.

Photodynamic therapy (PDT) is a treatment modality for certain malignant (skin, head and neck, gastrointestinal, gynecological cancers), premalignant (actinic keratosis), and nonmalignant (psoriasis) indications. Broader acceptance by the medical community and applicability is hampered, at least in part, by the less than optimal photophysical characteristics of the porphyrin derivatives. This situation sparked a worldwide search for novel sensitizers leading to new compounds, some holding more promise than others. The primary cytotoxic agent involved in the photodynamic action is singlet oxygen (Dg), the efficient generation of which is linked invariably to the intersystem crossing (ISC) efficiency of the excited sensitizer. Most organic dyes have low triplet quantum yields, and in many recent candidates for photodynamic sensitizers, heavy atoms are incorporated into the structure as a strategy to improve spin–orbit coupling leading to facilitated intersystem crossing. While this approach seems fail-safe, incorporation of heavy atoms such as bromine, iodine, selenium, and certain lanthanides very often leads to increased “dark toxicity”. Unlike traditional chemotherapy agents, in principle, photodynamic therapy sensitizers themselves can be nontoxic, either at cellular or organ levels, even at relatively high concentrations. We have been interested in trying to find alternative ways of achieving increased intersystem crossing without the use of heavy atoms to minimize dark toxicity, turning our attention to the excitedstate properties of the sensitizers. Designing efficient photoinduced O2 generators requires that any existing operative fluorescence cycle of the fluorophore, which is through the S0!S1!S0 states, has to be perturbed so as to minimize or shut down the S1!S0 deactivation, and switch to the triplet surface once S1 is accessed. A general design principle for a favorable S1!T1 transition from an electronic structure viewpoint would in principle require the structural and electronic compatibility of the S1 and T1 states to surpass that of the S1–S0 pair. Once multiple electronic states come into play, quantum mechanical calculations providing a detailed understanding of the electronic structure are extremely helpful. Multi-configurational self-consistent field (MCSCF) techniques are the stateof-the-art computational chemistry approaches, when near degeneracies and excited states are considered. These methods may not reach chemical accuracy ( 2–3 kcalmol ) for computing total energies, but they are crucial for a qualitatively correct description of the excited states and are capable of providing a conceptually complete picture of the photophysics taking place. Therefore, we mainly employed a popular variant of MCSCF techniques; the complete active space SCF (CASSCF) method in combination with relatively large basis sets and different active spaces. Details of CASSCF calculations are provided in the Supporting Information. Our calculations on the parent Bodipy (4,4-difluoro-4-bora-3a,4adiaza-s-indacene, Scheme 1) showed that natural orbital occupancies of the S1 state describe an open-shell singlet with essentially double (> 1.9) or zero (< 0.1) electrons for all orbitals except the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) that are singly occupied (see the Supporting Information, Figure S1). It is no surprise to observe a fluorophore with low triplet quantum yield to have an excited state that possesses only two orbitals with single occupancy. Hence, to achieve our goal of efficient switching to the triplet manifold, we have to access excited states that differ from the ones that arise from simple HOMO!LUMO transitions. Among multiply excited configurations, doubly substituted ones are particularly important in enhancing S1–T1 coupling as shown by the seminal work of Salem and Rowland and the following work by Michl. Thus, the substitutions should invoke a simultaneous two-electron excitation from the Scheme 1. Structure and numbering of the parent Bodipy compound. [*] Y. Cakmak, S. Kolemen, B. Kilic, Prof. Dr. E. U. Akkaya UNAM-Institute of Materials Science and Nanotechnology Bilkent University, Ankara, 06800 (Turkey) E-mail: eua@fen.bilkent.edu.tr

Assessment of DNA damage in nurses handling antineoplastic drugs by the alkaline COMET assay.

The widespread use of chemotherapy in the treatment of cancer has led to anxiety about the possible hazards to staff involved in the preparation and administration of cytotoxic agents. Careless handling of antineoplastic drugs may lead to exposure in detectable amounts by means of chemical or biological methods in the body fluids or cell samples but the information about the mutagenic effects of these agents on nurses is limited and inconsistent. DNA damage in peripheral lymphocytes of 30 professional nurses employed in the oncology departments for at least 6 months were examined by the alkaline single cell gel electrophoresis, COMET technique. The results were compared to that of 30 controls with comparable age, sex and smoking habits, not practising in the chemotherapy services. Work characteristics of the exposed nurses and the use of personal protective equipment were also investigated. The DNA damage observed in the lymphocytes of the nurses was significantly higher than the controls (p<0.001). The observed DNA damage was found to be significantly lower (p<0.001) in nurses applying the necessary individual safety protections during their work. Cigarette smoking was not related to increases in DNA damage, also a significant association was not found between the duration of occupational exposure to antineoplastic drugs and the DNA damage.

Water soluble distyryl-boradiazaindacenes as efficient photosensitizers for photodynamic therapy

We introduce a novel class of water soluble, extended conjugation boradiazaindacene dyes which are efficient singlet oxygen generators and have spectacular photoinduced cytotoxicity when excited in the therapeutic window of the electromagnetic spectrum.

Expression of the components and regulatory proteins of the alternative complement pathway and the membrane attack complex in normal and diseased synovium

SummaryWe have studied synthesis of the complement components and regulatory proteins of the alternative pathway and the membrane attack complex in synovial membrane. RNA was extracted from synovial tissue of patients with rheumatoid arthritis (RA) or osteoarthritis (OA) as well as from normal synovial membrane. Dot blot analysis showed the presence of mRNAs for all the complement components and regulatory proteins (C3, factor B, factor D, C5, C6, C7, C9, factor H, factor I, S-protein, SP-40, 40, DAF, MCP, CR1, CD59), except for properdin, C8α, C8β and C8γ in all three types of synovial membrane studied. In an attempt to determine which components were synthesised by each cell type, monocytes (mononuclear phagocytes), human umbilical vein endothelial cells (HUVEC), synovial membrane fibroblasts (from normal, OA and RA synovial membrane) and peripheral blood lymphocytes were cultured in vitro and secretion rates of individual components were measured and total cellular RNA analysed by northern blotting. Monocytes secreted properdin, C3, and factor H but not factor B, factor I, C5, C6, C7, C8 or C9. Fibroblasts and endothelial cells secreted factor B, factor H and factor I, but not properdin, C5, C6, C7, C8 or C9. Lymphocytes did not secrete any of these components. mRNAs encoding C3, factor B, factor H, S-protein, SP-40, 40, MCP and DAF were detected in all three other cell types (monocytes, fibroblasts and HUVEC), but factor I and CD59 mRNAs were not detected in monocytes. C5, C6, C7, C8α, C8β, CD8γ and C9 mRNAs were not detected in any of the cell types studied. Cell-specific differences were observed in the expression of the different mRNA species for DAF, MCP and CD59. The results of the present study demonstrate that synthesis of many complement components occurs in normal, RA and OA synovial membrane, and that this may be explained in part by synthesis in mononuclear phagocytes, endothelial cells and fibroblasts. The cellular sources of C5, C6, C7 and C9 mRNAs in synovial membrane have not been determined. The data also show that there are important cell-specific differences in the expression of the genes encoding both the alternative complement pathway components and the membrane regulatory components. These differences require further investigation.

HFE H63D mutation frequency shows an increase in Turkish women with breast cancer

BackgroundThe hereditary hemochromatosis gene HFE plays a pivotal role in iron homeostasis. The association between cancer and HFE hetero- or homozygosity has previously been shown including hepatocellular and nonhepatocellular malignancies. This study was performed to compare frequencies of HFE C282Y and H63D variants in Turkish women with breast cancer and healthy controls.MethodsArchived DNA samples of Hacettepe University Oncology Institute were used in this study. The HFE gene was investigated by PCR-RFLP.ResultsAll subjects studied were free from C282Y mutation. Thirty-nine patients had H63D mutation and were all heterozygous. H63D allele frequency was 22.2% (39/176) in the breast cancer patients, and 14% (28/200) in the healthy volunteers. Statistical analysis of cases with HFE H63D phenotype showed significant difference between breast cancer and healthy volunteers (P = 0.02).ConclusionOur results suggest that HFE H63D mutation frequencies were increased in the breast cancer patients in comparison to those in the general population. Also, odds ratios (odds ratio = 2.05) computed in this study suggest that H63D has a positive association with breast cancer.

Effect of interferon β-1a on serum matrix metalloproteinase—9 (MMP-9) and tissue inhibitor of matrix metalloproteinase (TIMP-1) in relapsing remitting multiple sclerosis patients

Abstract.There is emerging evidence that matrix metalloproteinasesn(MMPs) might be involved in blood brain barrier (BBB) breakdownnin multiple sclerosis.A group of natural tissue inhibitors of metalloproteinasesn(TIMPS) regulates proteolytic activity to prevent tissue damage.nTIMP-1 and MMP-9 are known to be secreted as heterodimers andnTIMP-1 preferentially functions to inhibit MMP-9 activity. Innthis present study, the effects of IFNβ-1a on serum MMP-9 andnTIMP-1 were evaluated longitudinally during a one-year period.nThe MMP-9 levels showed no significant changes while TIMP-1nlevels gradually and significantly increased duringn3rd andn6th months of therapy compared withnpretreatment levels.

Evaluation of the cytotoxicity of calcium phosphate root canal sealers by MTT assay.

The purpose of this study was to evaluate the cytotoxicity of some calcium phosphate-based sealers (Sankin apatite root canal sealers (SARCS) types 1 to 3) in comparison with currently used sealers (CRCS, Ketac Endo, AH26, and Endomethasone) by using MTT assay on L929 cells. Monolayer cell cultures were prepared on 96-well plates. After incubation at 37 degrees C in a humidified 5% CO2-containing air atmosphere for 24 h in the presence of each sealer extracts, 25 microliters of 5 mg/ml of MTT in saline were added into each well and incubated a further 3 h at 37 degrees C. A solubilization buffer consisting of 23% sodium dodecyl sulfate in 50% N,N-dimethylformamide (pH 4.7) was used to dissolve formazan precipitate. The optical densities of the plates were then read by a microplate spectrophotometer at 570 nm. Greater magnitude of optical density due to intense blue coloring is regarded as showing a higher percentage of cell viability. Among the different types of sealers, SARCS types 1 to 3 and CRCS did not exert any cytotoxic effects, whereas AH26, Ketac Endo, and Endomethasone produced some cytotoxicity.

Expression of complement regulatory proteins CR1, DAF, MCP and CD59 in haematological malignancies

Abstract:

Effects of Persistent Atrial Fibrillation on Serum Galectin-3 Levels

Galectin-3 is known to play an important role in a number of fibrotic conditions, including cardiac fibrosis. Many studies have focused on the association between galectin-3 levels andxa0cardiac fibrosis in heart failure. However, the role of galectin-3 in the pathogenesis of atrial fibrillation (AF) has not been evaluated thoroughly yet. The aim of this study was to determine whether serum galectin-3 levels were elevated in patients with AF and preserved left ventricular function. Seventy-six patients with paroxysmal or persistent AF and preserved left ventricular systolic function and 75 age- and gender-matched control subjects were enrolled in this observational study. Galectin-3 levels were measured by enzyme-linked immunosorbent assay. Serum galectin-3 (median 0.6 ng/ml [interquartile range 0.2 to 1.4] vs 0.5 ng/ml [interquartile range 0.1 to 0.7], p <0.001) and left atrial volume index (LAVI) (mean 29.5 ± 3.5 vs 26.5 ± 2.5xa0ml/m(2), p <0.001) were significantly greater in patients with AF compared with the control group. Serum galectin-3 levels were also significantly higher in patients with persistent AF than those with paroxysmal AF (median 0.8 ng/ml [interquartile range 0.4 to 1.4] vs 0.5 ng/ml [interquartile range 0.2 to 0.9], p <0.001). Multivariate regression analysis demonstrated that serum galectin-3 (odds ratio 87.53, 95% confidence interval 6.06 to 1,265.03, pxa0= 0.001) and LAVI (odds ratio 1.38, 95% confidence interval 1.19 to 1.60, p <0.001) were independent predictors of AF. Only LAVI was independently correlated with serum galectin-3 levels in patients with AF in linear regression analysis. In conclusion, serum galectin-3 is significantly elevated and is also significantly correlated with LAVI in patients with AF with preserved left ventricular function.

Dihydropyrimidine Dehydrogenase Enzyme Deficiency: Clinical and Genetic Assessment of Prevalence in Turkish Cancer Patients

Background: Fluorouracil has been reported to induce severe side-effects in particular subjects who have deficiency in dehydropyrimidine dehyrogenase activity, the major enzyme in the catabolism of fluorouracil. Patients and methods: In this study, we aimed to analyze the heterozygote and homozygote frequencies of dehydropyrimidine dehyrogenase gene mutation in 200 patients receiving fluorouracil based chemotherapy together with the assessment of the toxicity profile of these chemotherapy regimens. Results: According to the results of clinical toxicity assessments, grade 3–4 hematologic toxicity was noted in 12% of the patients. Grade 3 gastrointestinal toxicity was present in 5% of the subjects with no grade 4 side effects. The heterozygote (2q(1−q)) and homozygote (q2) frequencies of dehydropyrimidine dehyrogenase gene mutation were calculated as 1.5% (3/200) and 0.000055% (1/18,043) in the analyzed samples. Conclusion: In this report, for the first time we documented the frequency of dehydropyrimidine dehydrogenase gene mutation in Turkish cancer patients. The determination of enzyme activity in suspected individuals and analysis of other mutations on a population basis would be the next steps for our country.