Benzodiazepine-based selective inhibitors of mitochondrial F1F0 ATP hydrolase

A series of benzodiazepine-based inhibitors of mitochondrial F(1)F(0) ATP hydrolase were prepared and evaluated for their ability to selectively inhibit the enzyme in the forward direction. Compounds from this series showed excellent potency and selectivity for ATP hydrolase versus ATP synthase, suggesting a potentially beneficial profile useful for the treatment of ischemic heart disease.     

N-[1-Aryl-2-(1-imidazolo)ethyl]-guanidine derivatives as potent inhibitors of the bovine mitochondrial F1F0 ATP hydrolase

A series of substituted guanidine derivatives were prepared and evaluated as potent and selective inhibitors of mitochondrial F(1)F(0) ATP hydrolase. The initial thiourethane derived lead molecules possessed intriguing in vitro pharmacological profiles, though contained moieties considered non-drug-like. Analogue synthesis efforts led to compounds with maintained potency and superior physical properties. Small molecules in this series which potently and selectivity inhibit ATP hydrolase and not ATP synthase may have utility as cardioprotective agents.     

Quinazolinone fungal efflux pump inhibitors. Part 2: In vitro structure-activity relationships of (N-methyl-piperazinyl)-containing derivatives

Structure-activity relationships of a novel series of fungal efflux pump inhibitors with respect to potentiation of the activity of fluconazole against strains of Candida albicans and Candida glabrata over-expressing ABC-type efflux pumps are systematically explored.     

Major histocompatibility complex and mate choice in sand lizards

In mice and man, females prefer males with a major histocompatibility complex (MHC) genotype different to their own. We tested whether this phenomenon also occurs in the Swedish sand lizard (Lacerta agilis). Females in a laboratory experiment preferred to associate with odour samples obtained from more distantly related males at the MHC class 1 loci. Data on free-ranging lizards suggest that associations between males and females are nonrandom with respect to MHC genotype. However, male spatial distribution and mobility during the mating season suggest that the non-random pairing process in the wild may also be driven by corresponding genetic benefits to males pairing with less related females.     

Three distinct epitopes on the extracellular face of the glucagon receptor determine specificity for the glucagon amino terminus

The glucagon and glucagon-like peptide-1 (GLP-1) receptors are homologous family B seven-transmembrane (7TM) G protein-coupled receptors, and they selectively recognize the homologous peptide hormones glucagon (29 amino acids) and GLP-1 (30-31 amino acids), respectively. The amino-terminal extracellular domain of the glucagon and GLP-1 receptors (140-150 amino acids) determines specificity for the carboxyl terminus of glucagon and GLP-1, respectively. In addition, the glucagon receptor core domain (7TM helices and connecting loops) strongly determines specificity for the glucagon amino terminus. Only 4 of 15 residues are divergent in the glucagon and GLP-1 amino termini; Ser2, Gln3, Tyr10, and Lys12 in glucagon and the corresponding Ala8, Glu9, Val16, and Ser18 in GLP-1. In this study, individual substitution of these four residues of glucagon with the corresponding residues of GLP-1 decreased the affinity and potency at the glucagon receptor relative to glucagon. Substitution of distinct segments of the glucagon receptor core domain with the corresponding segments of the GLP-1 receptor rescued the affinity and potency of specific glucagon analogs. Site-directed mutagenesis identified the Asp385 --> Glu glucagon receptor mutant that specifically rescued Ala2-glucagon. The results show that three distinct epitopes of the glucagon receptor core domain determine specificity for the N terminus of glucagon. We suggest a glucagon receptor binding model in which the extracellular ends of TM2 and TM7 are close to and determine specificity for Gln3 and Ser2 of glucagon, respectively. Furthermore, the second extracellular loop and/or proximal segments of TM4 and/or TM5 are close to and determine specificity for Lys12 of glucagon.     

Study of the infectivity of saline-stored Campylobacter jejuni for day-old chicks

The culturability of three Campylobacter jejuni strains and their infectivity for day-old chicks were assessed following storage of the strains in saline. The potential for colonization of chicks was weakened during the storage period and terminated 3 to 4 weeks before the strains became nonculturable. The results from this study suggest that the role of starved and aged but still culturable campylobacters may be diminutive, but even more, that the role of viable but nonculturable stages in campylobacter epidemiology may be negligible. Even high levels of maternally derived anti-campylobacter outer membrane protein serum antibodies in day-old chicks did not protect the chicks from campylobacter colonization.     

Molecular phylogeny of living xenarthrans and the impact of character and taxon sampling on the placental tree rooting

Extant xenarthrans (armadillos, anteaters and sloths) are among the most derived placental mammals ever evolved. South America was the cradle of their evolutionary history. During the Tertiary, xenarthrans experienced an extraordinary radiation, whereas South America remained isolated from other continents. The 13 living genera are relics of this earlier diversification and represent one of the four major clades of placental mammals. Sequences of the three independent protein-coding nuclear markers alpha2B adrenergic receptor (ADRA2B), breast cancer susceptibility (BRCA1), and von Willebrand Factor (VWF) were determined for 12 of the 13 living xenarthran genera. Comparative evolutionary dynamics of these nuclear exons using a likelihood framework revealed contrasting patterns of molecular evolution. All codon positions of BRCA1 were shown to evolve in a strikingly similar manner, and third codon positions appeared less saturated within placentals than those of ADRA2B and VWF. Maximum likelihood and Bayesian phylogenetic analyses of a 47 placental taxa data set rooted by three marsupial outgroups resolved the phylogeny of Xenarthra with some evidence for two radiation events in armadillos and provided a strongly supported picture of placental interordinal relationships. This topology was fully compatible with recent studies, dividing placentals into the Southern Hemisphere clades Afrotheria and Xenarthra and a monophyletic Northern Hemisphere clade (Boreoeutheria) composed of Laurasiatheria and Euarchontoglires. Partitioned likelihood statistical tests of the position of the root, under different character partition schemes, identified three almost equally likely hypotheses for early placental divergences: a basal Afrotheria, an Afrotheria + Xenarthra clade, or a basal Xenarthra (Epitheria hypothesis). We took advantage of the extensive sampling realized within Xenarthra to assess its impact on the location of the root on the placental tree. By resampling taxa within Xenarthra, the conservative Shimodaira-Hasegawa likelihood-based test of alternative topologies was shown to be sensitive to both character and taxon sampling.     

Sexual dimorphism in lizard body shape: the roles of sexual selection and fecundity selection

Sexual dimorphism is widespread in lizards, with the most consistently dimorphic traits being head size (males have larger heads) and trunk length (the distance between the front and hind legs is greater in females). These dimorphisms have generally been interpreted as follows: (1) large heads in males evolve through male-male rivalry (sexual selection); and (2) larger interlimb lengths in females provide space for more eggs (fecundity selection). In an Australian lizard (the snow skink, Niveoscincus microlepidotus), we found no evidence for ongoing selection on head size. Trunk length, however, was under positive fecundity selection in females and under negative sexual selection in males. Thus, fecundity selection and sexual selection work in concert to drive the evolution of sexual dimorphism in trunk length in snow skinks.     

Bacillus thuringiensis in fecal samples from greenhouse workers after exposure to B. thuringiensis-based pesticides

In a study of occupational exposure to Bacillus thuringiensis, 20 exposed greenhouse workers were examined for Bacillus cereus-like bacteria in fecal samples and on biomonitoring filters. Bacteria with the following characteristics were isolated from eight individuals: intracellular crystalline inclusions characteristic of B. thuringiensis, genes for and production of B. cereus enterotoxins, and positivity for cry11 as determined by PCR. DNA fingerprints of the fecal isolates were identical to those of strains isolated from the commercial products used. Work processes (i.e., spraying) correlated with the presence of B. thuringiensis in the fecal samples (10(2) to 10(3) CFU/g of feces). However, no gastrointestinal symptoms correlated with the presence of B. thuringiensis in the fecal samples.