Ehrlich II –2nd World Conference on Magic Bullets

Cytotoxic Platinum(II) Complexes With Quaterpyridine Ligands As A New Class Of Topoisomerase I Inhibitors LAI-MING WONG E^1, MA DL^1, LEUNG CH^1, SIU FM^1, WU P^1, CHE CM^1, YANG M^2 ^1Department of Chemistry and Open Laboratory of Chemical Biology of the Institute of Molecular Technology for Drug Discovery and Synthesis, The University of Hong Kong, Hong Kong; ^2Department of Biology and Chemistry, City University of Hong Kong, Kowloon, Hong Kong SAR (China) Background: Topoisomerase I (Topo I) has been receiving considerable interest due to its capability in regulation of cell division. The spatial arrangement of DNA before, during, and after replication is essential for cell division process. Topoisomerases regulate the linking number, twist, and writhe, ensuring that it is arranged adequately for DNA replication by breaking one or two strands of the DNA. Thus inhibition of topoisomerase by ternary (DNA–intercalator–Topo complex) formation is important in the context of drug discovery for anti-cancer treatment. Methods: The interactions of [Pt(dpQP)](CF3SO3)2, [1, dpQP = 4,4-diphenyl-2,2:6,2:6,2-quaterpyridine] with double-stranded DNA was examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van’t Hoff, and Gibbs±Helmholtz equations. The binding mode of 1 towards the TopoI-linked DNA was further studied by molecular modeling. Results: The binding of 1 to calf thymus DNA led to increases in the DNA melting temperature (Tm = +7 ^oC), modest hypochromism (12% of the absorption band at max of 358 nm). The binding constant of 1 with DNA, as determined by absorption titration, is (1.6 ± 0.2) 10^5 dm^3 mol^-1. A modeling study on the interaction between 1 and TopoI-linked DNA revealed that 1 intercalates to TopoI-DNA in a similar manner to topotecan (known topoisomerase I inhibitor), and exhibits a strong binding interaction. As determined by MTT assays, 1 exhibited moderate cytotoxicities toward several human cancer cell lines (KB-3-1, HepG2, and HeLa). According to confocal microscopic and flow cytometric studies, 1 induced apoptosis (70%) in cancer cells with <5% necrosis detected. Notably, 1 at concentrations > 25 M inhibited the Topo I-mediated relaxation of DNA. Conclusions: Cyclometalated platinum(II) complex with quaterpyridine ligand bind to DNA with binding constants ~10^5 mol^–1dm^3and exhibit comparable cytotoxicities toward a series of human carcinoma cell lines with cisplatin; can induce apoptotic cell death in human carcinoma cells presumably by stabilizing the ternary, DNA–intercalator–Topo complex.

Antiviral Chemotherapy In HTLV-1 Infection: Highlights From In Vitro Studies BALESTRIERI E^1, ASCOLANI A^2, MATTEUCCI C^1, BALZARINI J^3, MASTINO A^4, MACCHI B^2 ^1Dept Exp Med Bioch Sci ;^2Dept Neuroscience Univ Tor Vergata Rome, Italy; ^3 Rega Institute for Medical Research, K.U. Leuven, Leuven, Belgium;^4Department of Life Sciences, Section of Microbiological, Genetic and Molecular Sciences, University of Messina, Messina, Italy Background: Human T lymphotropic virus type 1 (HTLV-1) is associated to various pathologies. The most common characterized pathologies are adult T cell leukaemia (ATL), cutaneous T cell lymphoma (CTCL)], and neurological disease; tropic spastic paraparesis (TSP/HAM)]. Therapeutic treatments for HTLV-1-related pathologies are still limited and the classical chemotherapeutic approach has failed. A serious of studies has been recently carried on to define the effects of nucleoside analogues and carbohydrate binding agents (CBAs) in HTLV-1 in vitro infection. Methods: Quantitative analysis, of both a cell-free RT- inhibitory and cell-to cell transmission assays was performed to determine the effect of known nucleoside analogues (AZT,3TC, Tenofovir) and also a newly synthesized family of phosphonated nucleoside compounds (PCOANs). On the other side Carbohydrate-binding agents (CBAs) such as the Hippeastrum hybrid agglutinin (HHA), Urtica dioica agglutinin (UDA), and mannose-specific antibiotic Pradimicin A (PRM-A) were tested for their ability to block HTLV-1 transmission both to PBMC from a number of different normal adults or to lymphoid cell lines. Results: PCOANs, completely inhibited cDNA elongation at concentrations close to that necessary for tenofovir to exert a similar effect. PCOANs slightly induced toxicity levels similar to that of tenofovir and lower than that of azydothymidine. CBA were able to efficiently prevent cell-to-cell HTLV-1 transmission at non-toxic concentrations as evidenced by the lack of appearance of virus-specific mRNA and of the viral protein Tax in the acceptor cells. Conclusions: Overall, these results indicate that the family of PCOANs includes potential candidate compounds for ensuring a long lasting control of HTLV-1 infection. The anti-HTLV-1 properties of the CBAs highlight the importance of the envelope glycols in events underlying HTLV-1 passage from cell to cell and indicate that CBAs should be further investigated on their potential to prevent HTLV-1 infection, including mother-to-child virus transmission by cell-to-cell contact through breast milk feeding.

Calcium-Releasing Agent Exhibits Bioactive Effects In Endodontic Therapy MAEDA H^1, TOMOKIYO A^1, FUJII S^1, WADA N^2, MONNOUCHI S^1, HORI K^1, AKAMINE A^1 ^1Kyushu Univ., Fukuoka, Japan; ^2Univ. Adelaide, Adelaide, Australia Background: Mineral trioxide aggregate (MTA) that is mainly composed of dicalcium silicate, tricalcium silicate, tricalcium aluminate, and gypsum, has been effectively used for endodontic applications. That resulted in the favorable healing involving the hard tissue regeneration by periodontal ligament (PDL) fibroblasts that cover the surface of tooth root. However, it has been unclear how MTA contributes to such healing. Therefore, we aimed to clarify the mechanism of MTA to influence human periodontal ligament fibroblasts (HPLF) in vitro. Methods: Two HPLF populations were isolated and generated from the healthy premolars of a 22-year-old female, and a 14-year-old male who visited Kyushu University Hospital for extraction, and the cells were maintained in 10%FBS/MEM (Gibco-BRL, Grand Island, NY). All procedures were performed in compliance with the regulations of Kyushu University. White ProRoot MTA (DENTSPLY Tulsa Dental, Johnson City, TN) was mixed with sterile water according to the manufacturer’s instructions, dispensed into plastic lids of 1.5ml micro-centrifuge tubes, and placed in a humidified incubator (37°C) for 12hr. MTA discs (9mm and 1mm thickness) were then rinsed with MEM, placed in 24-well culture plates (1disk/well), and subjected to the cultures with HPLF. Results: SEM observation showed attachment of HPLF onto MTA discs within 24hr. MTA did not inhibit the cell proliferation, and furthermore up-regulated expression of bone-related genes, osteopontin and osteocalcin in HPLF within 14days, and eventually induced mineralization in HPLF around MTA after 4wk of culture. MTA furthermore exhibited calcium release into the culture media. Then CaCl2 treatment not only stimulated mRNA expression of osteopontin and osteocalcin, but induced mineralization in HPLF, while MaCl2 treatment did not show any significant effects. Consequently, HPLF treated with MTA and CaCl2 definitely increased bone morphogenic protein 2 (BMP2) gene expression. Conclusions: 1) MTA possesses the biocompatibility for HPLF. 2) MTA induces the osteogenic differentiation of HPLF through up-regulated BMP2 expression via the calcium release. Therefore, 3) MTA is a bioactive material in endodontic treatment.

Antimicrobial Resistance Among Re Treatment TB Patients; Sri Lankan Experience MAGANA-ARACHCHI DN^1,2, PERERA AJ^2, SENARATNE V^3,DE SILVA K^3 Institute of Fundamental Studies, Sri Lanka, ^2Department of Microbiology, University of Colombo, Sri Lanka, ^3Central Chest Hospital, Welisara, Sri Lanka Background: The successful treatment of tuberculosis (TB) depends upon the selection of an effective chemotherapeutic regimen. Although the clinical accuracy of drug susceptibility test (DST) has been debated, it produces reliable results for susceptibility to isoniazid, rifampin and streptomycin. Therefore DST is essential for detecting drug resistant TB and designing effective regimens for treating individual patients. In Sri Lanka, the DST is performed only for first line anti-tuberculosis drugs. Aim; to determine the resistance patterns of Mycobacterium tuberculosis isolated from re treatment TB patients to first and second line anti tuberculosis drugs. Method: The study population consisted of 131culture positive TB patients admitted for re-treatment (38 relapses, 92 defaulters, 1 treatment failure) to Chest Hospital, Welisara. Sputum samples were decontaminated using standard sodium hydroxide – sodium citrate method. DSTs were done for 12 anti tuberculosis drugs with actively growing 4-week-old cultures grown on Middle brook 7H-10-agar using the agar proportion method. RESULTS: Table 1; Pattern of Drug resistance among tested isolates Number Susceptible to all drugs 63 Resistant to one/more first line drugs 20 Resistant to one/more second line drugs 17 Resistant to first & second line drugs 28