Discovery of Q203, a potent clinical candidate for the treatment of tuberculosis

New therapeutic strategies are needed to combat the tuberculosis pandemic and the spread of multidrug-resistant (MDR) and extensively drug-resistant (XDR) forms of the disease, which remain a serious public health challenge worldwide1, 2. The most urgent clinical need is to discover potent agents capable of reducing the duration of MDR and XDR tuberculosis therapy with a success rate comparable to that of current therapies for drug-susceptible tuberculosis. The last decade has seen the discovery of new agent classes for the management of tuberculosis3, 4, 5, several of which are currently in clinical trials6, 7, 8. However, given the high attrition rate of drug candidates during clinical development and the emergence of drug resistance, the discovery of additional clinical candidates is clearly needed. Here, we report on a promising class of imidazopyridine amide (IPA) compounds that block Mycobacterium tuberculosis growth by targeting the respiratory cytochrome bc1 complex. The optimized IPA compound Q203 inhibited the growth of MDR and XDR M. tuberculosis clinical isolates in culture broth medium in the low nanomolar range and was efficacious in a mouse model of tuberculosis at a dose less than 1 mg per kg body weight, which highlights the potency of this compound. In addition, Q203 displays pharmacokinetic and safety profiles compatible with once-daily dosing. Together, our data indicate that Q203 is a promising new clinical candidate for the treatment of tuberculosis

Moult cycle specific differential gene expression profiling of the crab Portunus pelagicus

Background: Crustacean moulting is a complex process involving many regulatory pathways. A holistic approach to examine differential gene expression profiles of transcripts relevant to the moulting process, across all moult cycle stages, was used in this study. Custom cDNA microarrays were constructed for Portunus pelagicus. The printed arrays contained 5000 transcripts derived from both the whole organism, and from individual organs such as the brain, eyestalk, mandibular organ and Y-organ from all moult cycle stages.Results: A total of 556 clones were sequenced from the cDNA libraries used to construct the arrays. These cDNAs represented 175 singletons and 62 contigs, resulting in 237 unique putative genes. The gene sequences were classified into the following biological functions: cuticular proteins associated with arthropod exoskeletons, farnesoic acid O-methyltransferase (FaMeT), proteins belonging to the hemocyanin gene family, lectins, proteins relevant to lipid metabolism, mitochondrial proteins, muscle related proteins, phenoloxidase activators and ribosomal proteins. Moult cycle-related differential expression patterns were observed for many transcripts. Of particular interest were those relating to the formation and hardening of the exoskeleton, and genes associated with cell respiration and energy metabolism.Conclusions: The expression data presented here provide a chronological depiction of the molecular events associated with the biological changes that occur during the crustacean moult cycle. Tracing the temporal expression patterns of a large variety of transcripts involved in the moult cycle of P. pelagicus can provide a greater understanding of gene function, interaction, and regulation of both known and new genes with respect to the moulting process

Istraživanje mehanizma toksičnosti anilina u eritrocitima

Strategies for the use of bio-indicators in the prediction of environmental damage should include mechanistic research. This study involves the relationship between the chemical structure and hemotoxic markers of aniline and its halogenated analogs. Aniline-induced methemoglobinemia, loss of circulating blood cells, blood stability, glutathione depletion and membrane cytoskeletal changes were assessed following exposure to phenylhydroxylamine (PHA), para-fluoro-, para-bromo-, and para-iodo in male Sprague-Dawley rats. Methemoglobin was determined spectrophotometrically at 635 nm. Erythrocyte depletion was investigated by loss of radioactivity in chromium-labeled red blood cells in vivo. Membrane proteins were analyzed by SDS-PAGE using red blood ghost cells treated with various aniline analogs. Results showed dose- and time-dependent changes in the induction of methemoglobin of up to 78 % with para-bromo PHA and 75 % with para-iodo PHA compared to 3 % to 5 % in control. Treated animals lost up to three times more blood from circulation compared to control within 14 days after treatment. Erythrocytes were more stable in buffer solution than in para-iodo-treated cells. Depletion of reduced glutathione in PHA and para-iodo-PHA treated red cells was also observed. Analysis of red cell skeletal membrane treated with para-iodo-PHA showed that protein band 2.1 became broader and band 2.2 diminished completely in some treatments. Dose- and time-dependent changes suggested the use of hemotoxic endpoints as potential biomarkers for assessing chemical and drug safetyStrategije primjene biopokazatelja za predviđanje štete u okolišu trebaju u obzir uzeti istraživanja mehanizama djelovanja. Ovo istraživanje propituje odnos između kemijske strukture i hemotoksičnih pokazatelja djelovanja anilina i njegovh halogeniranih analoga. Nakon izlaganja mužjaka štakora soja Sprague-Dawley para-fluoro-, para-bromo- i para-jodofenilhidroksilaminu, utvrđena je methemoglobinemija uzrokovana anilinom te pad broja krvnih stanica u krvotoku i stabilnosti krvi, gubitak glutationa i promjene na membrani stanice. Methemoglobin je određivan spektrofotometrijski na 635 nm. Pad broja eritrocita mjeren je in vivo s pomoću eritrocita obilježenih radioaktivnim kromom. Membranske su bjelančevine analizirane s pomoću SDS-PAGE, rabeći eritrocite bez hemoglobina (engl. ghost cells) kojima su dodani različiti analozi anilina. Nalazi upućuju na promjene indukcije methemoglobina ovisno o dozi i vremenu djelovanja do 78 % s para-bromo-fenilhidroksilaminom te do 75 % s para-jodofenilhidroksilaminom u usporedbi s 3 % do 5 % u kontrolnih uzoraka. U razdoblju od 14 dana nakon tretiranja izložene životinje izgubile su tri puta više krvi iz krvotoka od kontrolnih. Eritrociti su bili stabilniji u puferskoj otopini negoli u stanicama kojima je dodan para-jodofenilhidroksilamin. Zamijećen je i pad glutationa u eritrocitima kojima je dodan fenilhidroksilamin odnosno para-jodofenilhidroksilamin. Analizom membrane eritrocita kojima je dodan para-jodofenilhidroksilamin zamijećeno je da se u pojedinih obrada raširila proteinska vrpca 2.1, a potpuno smanjila proteinska vrpca 2.2. Zamijećene promjene uvjetovane dozom i vremenom upućuju na primjenu hemotoksičnih parametara kao mogućih biopokazatelja u procjeni sigurnosti lijeka odnosno kemikalije

The bc 1 complexes of Rhodobacter sphaeroides and Rhodobacter capsulatus

Photosynthetic bacteria offer excellent experimental opportunities to explore both the structure and function of the ubiquinol-cytochrome c oxidoreductase ( bc 1 complex). In both Rhodobacter sphaeroides and Rhodobacter capsulatus , the bc 1 complex functions in both the aerobic respiratory chain and as an essential component of the photosynthetic electron transport chain. Because the bc 1 complex in these organisms can be functionally coupled to the photosynthetic reaction center, flash photolysis can be used to study electron flow through the enzyme and to examine the effects of various amino acid substitutions. During the past several years, numerous mutations have been generated in the cytochrome b subunit, in the Rieske iron-sulfur subunit, and in the cytochrome c 1 subunit. Both site-directed and random mutagenesis procedures have been utilized. Studies of these mutations have identified amino acid residues that are metal ligands, as well as those residues that are at or near either the quinol oxidase (Q o ) site or the quinol reductase (Q i ) site. The postulate that these two Q-sites are located on opposite sides of the membrane is supported by these studies. Current research is directed at exploring the details of the catalytic mechanism, the nature of the subunit interactions, and the assembly of this enzyme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44795/1/10863_2004_Article_BF00762582.pd