Substitution of terminal amide with 1H-1,2,3-triazole: Identification of unexpected class of potent antibacterial agents

3-Methoxybenzamide (3-MBA) derivatives have been identified as novel class of potent antibacterial agents targeting the bacterial cell division protein FtsZ. As one of isosteres for the amide group, 1,2,3-triazole can mimic the topological and electronic features of the amide, which has gained increasing attention in drug discovery. Based on these considerations, we prepared a series of 1H-1,2,3-triazole-containing 3-MBA analogues via isosteric replacement of the terminal amide with triazole, which had increased antibacterial activity. This study demonstrated the possibility of developing the 1H-1,2,3-triazole group as a terminal amide-mimetic element which was capable of both keeping and modulating amide-related bioactivity. Surprisingly, a different action mode of these new 1H-1,2,3-triazole-containing analogues was observed, which could open new opportunities for the development of antibacterial agents.     

Synthesis of triazole-Tethered pyrrolidine libraries: novel ECE inhibitors

The solid-phase synthesis of substituted 1,2,4-triazoles tethered to a 4-mercaptopyrrolidine core 1 is described. This novel class of non-peptidic, Zn(2+) metallo-protease inhibitors was found to have inhibitory activity for the endothelin converting enzyme (ECE-1). The SAR of the substitution pattern in 1 is discussed.     

Cell-mediated reduction of protein and peptide hydroperoxides to reactive free radicals

Radical attack on proteins in the presence of O(2) gives protein hydroperoxides in high yields. These peroxides are decomposed by transition metal ions, reducing agents, UV light and heat, with the formation of a range of reactive radicals that are capable of initiating further damage. Evidence has been presented for the formation of alcohols as stable products of peroxide decomposition, and these have been employed as markers of oxidative damage in vivo. The mechanism of formation of these alcohols is unclear, with both radical and nonradical pathways capable of generating these products. In this study we have investigated the reduction of peptide and protein hydroperoxides by THP-1 (human monocyte-like) cells and it is shown that this process is accompanied by radical formation as detected by EPR spin trapping. The radicals detected, which are similar to those detected from metal-ion catalyzed reduction, are generated externally to the cell. In the absence of cells, or with cell-conditioned media or cell lysates, lower concentrations of radicals were detected, indicating that intact cells are required for rapid hydroperoxide decomposition. The rate of radical generation was enhanced by preloading the cells with ascorbate, and this was accompanied by intracellular formation of the ascorbate radical. It is proposed that decomposition of some amino acid and peptide hydroperoxides occurs extracellularly via the involvement of a cell-surface reducing system, such as a trans-plasma membrane electron transport system (TPMET) either directly, or indirectly via redox cycling of trace transition metal ions.     

Mitochondrial DNA suggests at least 11 origins of parasitism in angiosperms and reveals genomic chimerism in parasitic plants

Background  

Some of the most difficult phylogenetic questions in evolutionary biology involve identification of the free-living relatives of parasitic organisms, particularly those of parasitic flowering plants. Consequently, the number of origins of parasitism and the phylogenetic distribution of the heterotrophic lifestyle among angiosperm lineages is unclear.     

Immunocytochemical localization of serotonin in the brain and pituitary gland of the platyfish,Xiphophorus maculatus

Summary Immunoreactive serotonin (ir-5HT) containing cells were localized in the brain and pituitary gland of the platyfish by use of immunoperoxidase procedures. In the brain, ir-neurons were found lining the wall of the third ventricle and in its lateral and posterior recesses. More caudally, ir-perikarya were found in the valvular portion of the cerebellum and in the raphe region. Ir-5HT was also localized within the pineal gland in fish that had been sacrificed before 1:00 p.m. Within the pituitary gland, ir-5HT was localized in periodic acid Schiff-positive cells of the pars intermedia of all fish while, in only a few animals, less intense immunoreactivity was also present in gonadotrops of the caudal pars distalis.     

The Microbiology of Built Up Poultry Litter

The numbers of viable bacteria in built up poultry litter were found to be 10¹⁰-10¹¹/g fresh weight and appeared to be little affected by factors such as age, temperature, moisture content and pH. Counts for unused litter and poultry droppings were lower. In built up litter of high alkalinity coryneform bacteria were predominant; micrococci occurred sporadically and small numbers of nocardias, streptomycetes, aerobic spore formers and streptococci were encountered. A variety of Gram negative bacteria also occurred, the numbers of which appeared to be controlled by alkalinity; they were less abundant in litters where the pH and buffering capacity were high. Strongly alkaline conditions also tended to lower the fungal counts but had no effect on the count of enterococci.     

Cholesterol sensitivity of detergent resistance: a rapid flow cytometric test for detecting constitutive or induced raft association of membrane proteins.

BACKGROUND: Lipid rafts are cholesterol- and glycosphingolipid-rich microdomains in the cellular plasma membranes that play critical roles in compartmentalization (concentration, coupling, and isolation) of receptors and signal molecules. Therefore, detecting constitutive or induced raft associations of such proteins is of central interest in cell biology. This has mostly been done with time- and cell-consuming immunobiochemical techniques affected by several sources of artifacts. A flow cytometric analysis of immunocytochemical staining under differential circumstances of detergent treatment offers a new alternative to this method. METHODS: Membrane microdomains are resistant to nonionic detergents due to extensive, strong interactions between their molecular constituents. We used this feature to develop a rapid flow cytometric assay of differential detergent resistance based on immunocytochemical labeling of extracellular domain epitopes in membrane proteins. Data evaluation is based on comparative detection of their detergent solubility without and with cholesterol depletion of cell membranes, resolved by moderate concentrations of nonionic detergents. RESULTS: Nonionic detergents Triton X-100 and Nonidet-40 (0.05-0.1%) in cold or Brij-98 (0.1-0.5%) at 37 degrees C efficiently resolved detergent solubility or resistance of many lymphocyte cell surface proteins. Kinetic data revealed that a short (5-10 min) detergent treatment is sufficient for this assay. Comparison of detergent solubility in untreated and cholesterol-depleted cells differentiated membrane proteins associated with or excluded from raft microdomains, respectively. Confocal microscopy showed that this mild detergent treatment leaves the cytoskeleton of the cells intact, with a detectable expression of raft marker detergent-resistant proteins attached to it. An induced association with rafts of immunoglobulin E receptors upon antigen cross-linking was also easily detectable in rat mast cells by this approach. CONCLUSIONS: A protocol is proposed for a rapid (5-10 min) test of detergent resistance of membrane proteins in cells. The approach requires only a small amount of cells (10(4)/sample) and offers a good resolution of detergent solubility or resistance of membrane proteins, also in terms of the underlying mechanisms, with an advantage of applicability for all conventional bench-top flow cytometers.     

Thiol end-capped titanium-copper complexes: Synthesis, solid state structure and electrochemical behavior

The synthesis of acetylene, acyl-thiol and thiol end-capped titanium-copper π-tweezer complexes of the structural type {[Ti](μ-σ,π-CCR)₂}CuSC₆H₄-4-R′ ([Ti] = (η⁵-C₅H₄SiMe₃)₂Ti; 3: R = SiMe₃, R′ = CCH; 5a: R = SiMe₃, R′ = SC(O)Me; 5b: R = ^tBu, R′ = SC(O)Me), {[Ti](μ-σ,π-CCSiMe₃)₂}CuSC₆H₄-C₆H₄-4-SH (7) and ({[Ti](μ-σ,π-CCR)₂}CuSC₆H₄)₂ (8) is described. Homobimetallic 3, 5a and 5b are accessible via the reaction of {[Ti](μ-σ,π-CCR)₂}CuMe (1a: R = SiMe₃, 1b: R = ^tBu) with stoichiometric amounts of Me(O)CS-1-C₆H₄-4-CCH (2) and C₆H₄-1,4-(SC(O)Me)₂ (4), respectively. Within these reactions the copper-sulfur bond formation is accompanied by the elimination of acetone. If 1a is treated with the dithiol (HS-C₆H₄)₂ (6) in a ratio of 1:1 or 2:1 than dinuclear 7 and tetranuclear 8 are produced upon formation of methane. Both types of reaction allow in a straightforward manner the synthesis of analytically pure samples in high yield. In addition, complex 8 is also formed, when equimolar amounts of 7 are reacted with1a.The solid state structure of 5a is reported. This complex possesses a low-valent CuSC₆H₄-4-SC(O)Me entity with copper(I) in a planar surrounding. All other geometrical features are in agreement with the expected data relevant for Ti-Cu organometallic π-tweezer complexes.Cyclic voltammetric studies were carried out with 3-8. The results are discussed with respect to intramolecular interactions between the various electrochemically active reaction sites.     

Controlling soil-transmitted helminthiasis in pre-school-age children through preventive chemotherapy

Pre-school age children account for 10%-20% of the 2 billion people worldwide who are infected with soil-transmitted helminths (STHs): Ascaris lumbricoides (roundworm), Trichuris trichiura (whipworm), and Ancylostoma duodenale/Necator americanus (hookworms). Through a systematic review of the published literature and using information collated at World Health Organization headquarters, this paper summarizes the available evidence to support the recommendation that pre-school children should be included in regular deworming programmes. The first section describes the burden of STH disease in this age group, followed by a summary of how infection impacts iron status, growth, vitamin A status, and cognitive development and how STHs may exacerbate other high mortality infections. The second section explores the safety of the drugs themselves, given alone or co-administered, drug efficacy, and the importance of safe administration. The third section provides country-based evidence to demonstrate improved health outcomes after STH treatment. The final section provides country experiences in scaling up coverage of pre-school children by using other large scale public health interventions, including vitamin A programmes, immunization campaigns, and Child Health days. The paper concludes with a number of open research questions and a summary of some of the operational challenges that still need to be addressed.     

Changes in marsh nekton communities along the salinity gradient of the Schelde river, Belgium and The Netherlands

Nekton was sampled in five marshes along the salinity gradient of the Schelde River. The utilisation of three different habitats (large and small creek, marsh pond) by fish and macrocrustacean species was compared among the five sampling sites. In the larger channels fyke nets were deployed to capture fish and macrocrustaceans leaving the marsh at ebb while block nets were set in smaller intertidal creeks. Fish traps passively sampled fish and shrimp in the marsh ponds. The tidal freshwater marsh had a species poor fauna and only a low number of fish was caught. Besides some freshwater species (Alburnoides bipunctatus, Carassius carassius) the European eel, Anguilla anguilla was still present. The four other marshes had a similar community structure although Platichthys flesus was absent from the euhaline area. Among fish species, dominance of Dicentrarchus labrax, Platichthys flesus and Pomatoschistus microps was observed. Carcinus maenas and Palaemonetes varians were the most abundant macrocrustacean species in every marsh. Between the large and small intertidal creeks there was no difference in nekton species composition. The main species used both habitats. Marsh ponds were utilized intensively only by two species, Pomatoschistus microps and Palaemonetes varians in every marsh.