Ligands for insulin receptor isolation

Biotinylated insulins are bivalent molecules having the ability to bind to insulin receptors on the one hand and to "avidins" on the other. In order to be useful as ligands for insulin receptor isolation, biotinylated insulins must be developed that have the capacity to bind simultaneously to both and insulin receptor. The present investigation addresses this problem. A series of biotinylated and dethiobiotinylated insulins has been prepared in which the distance between the biotin carboxyl group and the insulin varies from 7 to 20 atoms. These compounds form complexes with succinoylavidin. The dissociation rates (K-1) of these complexes have been determined from the [14C]biotin exchange assay. The dissociation kinetics of most of these complexes are biphasic, and the kinetic constants reported are those corresponding to the slow rate. Ligands containing dethiobiotin dissociate more rapidly than the corresponding biotin derivatives. The interposition of a spacer arm substantially decreases the rate of dissociation. The [14C]biotin exchange assay could not be used with streptavidin complexes of the above ligand since biotin dissociates more rapidly from streptavidin than from succinoylavidin. However, the relative dissociation rates of a series of ligands could be determined and were as follows: 6-(dethiobiotinylamido)-hexanoic acid greater than dethiobiotinyl-A1-insulin greater than biotinylinsulin greater than biotinyl-A1-insulin greater than biotinyl-A2-insulin. Dethiobiotin and its amide failed to form complexes with streptavidin. The affinity of the ligands for insulin receptors was determined by measuring their ability to stimulate 14CO2 formation from [1-14C]glucose in rat epididymal adipocytes.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improvement of Disease Prediction and Modeling through the Use of Meteorological Ensembles: Human Plague in Uganda

Climate and weather influence the occurrence, distribution, and incidence of infectious diseases, particularly those caused by vector-borne or zoonotic pathogens. Thus, models based on meteorological data have helped predict when and where human cases are most likely to occur. Such knowledge aids in targeting limited prevention and control resources and may ultimately reduce the burden of diseases. Paradoxically, localities where such models could yield the greatest benefits, such as tropical regions where morbidity and mortality caused by vector-borne diseases is greatest, often lack high-quality in situ local meteorological data. Satellite- and model-based gridded climate datasets can be used to approximate local meteorological conditions in data-sparse regions, however their accuracy varies. Here we investigate how the selection of a particular dataset can influence the outcomes of disease forecasting models. Our model system focuses on plague (Yersinia pestis infection) in the West Nile region of Uganda. The majority of recent human cases have been reported from East Africa and Madagascar, where meteorological observations are sparse and topography yields complex weather patterns. Using an ensemble of meteorological datasets and model-averaging techniques we find that the number of suspected cases in the West Nile region was negatively associated with dry season rainfall (December-February) and positively with rainfall prior to the plague season. We demonstrate that ensembles of available meteorological datasets can be used to quantify climatic uncertainty and minimize its impacts on infectious disease models. These methods are particularly valuable in regions with sparse observational networks and high morbidity and mortality from vector-borne diseases.     

Initial responses of rove and ground beetles (Coleoptera,Staphylinidae, Carabidae) to removal of logging residues following clearcut harvesting in the boreal forest of Quebec,Canada

Increased interest in biomass harvesting for bioenergetic applications has raised questions regarding the potential ecological consequences on forest biodiversity. Here we evaluate the initial changes in the abundance, species richness and community composition of rove (Staphylinidae) and ground beetles (Carabidae), immediately following 1) stem-only harvesting (SOH), in which logging debris (i.e., tree tops and branches) are retained on site, and 2) whole-tree harvesting (WTH), in which stems, tops and branches are removed in mature balsam fir stands in Quebec, Canada. Beetles were collected throughout the summer of 2011, one year following harvesting, using pitfall traps. Overall catch rates were greater in uncut forest (Control) than either stem-only or whole-tree harvested sites. Catch rates in WTH were greater than SOH sites. Uncut stands were characterized primarily by five species: Atheta capsularis, Atheta klagesi, Atheta strigosula, Tachinus fumipennis/frigidus complex (Staphylinidae) and to a lesser extent to Pterostichus punctatissimus (Carabidae). Increased catch rates in WTH sites, where post-harvest biomass was less, were attributable to increased catches of rove beetles Pseudopsis subulata, Quedius labradorensis and to a lesser extent Gabrius brevipennis. We were able to characterize differences in beetle assemblages between harvested and non-harvested plots as well as differences between whole tree (WTH) and stem only (SOH) harvested sites where logging residues had been removed or left following harvest. However, the overall assemblage response was largely a recapitulation of the responses of several abundant species.     

Binding and autophosphorylating activity of human insulin analogs

Insulin receptor binding and autophosphorylating activities of a number of synthetic analogs of human insulin have been examined using highly purified insulin receptor from human placenta. In general, autophosphorylation correlates well with the ability of the analogs to stimulate glucose oxidation and to inhibit lipolysis in adipocytes although their biological activities varied over a wide range. These findings support the hypothesis that autophosphorylation is an obligatory step in the pathways leading to glucose oxidation and inhibition of lipolysis. The relative biological potencies of the analogs in the autophosphorylation assay also correlated well with their receptor-binding affinities except for the peptides [endo-TyrB16a]insulin, in which an additional Tyr has been inserted between TyrB16 and LeuB17 and [ProA2]insulin. The relative receptor binding affinity of [endo-TyrB16a]insulin is significantly greater than its biological activity in the adipocyte or receptor autophosphorylation assays. The converse is true for [ProA2]insulin. These results demonstrate that the amino-acid residues involved in binding and receptor activation may not be identical.     

Truncated human LMP-1 triggers differentiation of C2C12 cells to an osteoblastic phenotype in vitro

LIM mineralization protein-1 （LMP-1） is a novel intracellular osteoinductive protein that has been shown to induce bone formation both in vitro and in viva. LMP-1 contains an N-terminal PDZ domain and three C-terminal LIM domains. In this study, we investigated whether a truncated form of human LMP-1 （hLMP-1 [t]）, lacking the three C-terminal LIM domains, triggers the differentiation of pluripotent myoblastic C2C12 cells to the osteoblast lineage. C2C12 cells were transiently transduced with AdS-hLMP-1 （t）-green fluorescent protein or viral vector control. The expression of hLMP-1 （t） RNA and the truncated protein were examined. The results showed that hLMP-1 （t） blocked myotube formation in C2C12 cultures and significantly enhanced the alkaline phosphatase （ALP） activity. In addition, the expressions of ALP, osteocalcin, and bone morphogenetic protein （BMP）-2 and BMP-7 genes were also increased. The induction of these key osteogenic markers suggests that hLMP- 1 （t） can trigger the pluripotent myoblastic C2C12 cells to differentiate into osteoblastic lineage, thus extending our previous observation that LMP-1 and LMP-1 （t） enhances the osteoblastic phenotype in cultures of cells already committed to the osteoblastic lineage. Therefore, C2C12 cells are an appropriate model system for the examination of LMP-1 induction of the osteoblastic phenotype and the study of mechanisms of LMP-1 action.     

Profiling of E-cadherin, beta-catenin and Ca(2+) in embryo-uterine interactions at implantation

Establishment of early pregnancy is promoted by a complex network of signalling molecules that mediate cell-to-cell and cell-to-extracellular matrix communications between the receptive endometrium and the invasive trophectoderm. In this study, we have attempted to evaluate the expression profiles of cadherin and catenin during embryo implantation in the mouse. Western blotting studies along with immunocytochemical analysis revealed that E-cadherin is expressed rather ubiquitously in the uterine epithelial cells, distinct enrichment is observed on the apical membrane in the endometrium of peri-implantation uterus specifically at the implantation sites and not at the inter-implanation sites. beta-Catenin also is upregulated and is specifically restricted to apical membrane of epithelial cells of implantation sites. Progesterone induced expression of E-cadherin and 17beta-estradiol regulated the expression of catenin in implantation-delayed uteri. Interestingly, estradiol imparted negative modulation on cadherin expression when co-administered with progesterone. On the contrary, trophoblast exhibits a striking down regulation of cadherin, catenin and Ca(2+) at peri implanting stage. These observations suggest that the trophoblasts exhibited an invasive phenotype while the endometrial epithelium displayed an adhesive phenotype during the window of implantation. Thus, embryo implantation presents an instance where two interacting surfaces showed mutually complementing interaction phenotypes.     

Half-sandwich Mo(III) complexes with asymmetric diazadiene ligands

The asymmetric 1,4-diazadiene ligands R^∗NCHCHNR^∗ [R^∗ = (S)-CH(CH₃)Ph], , and 2,2′-bis(4-ethyloxazoline), as-ox, have been used to generate half-sandwich Mo^III derivatives by addition to Cp₂Mo₂Cl₄. Ligand affords a mononuclear, paramagnetic 17-electron product, , whereas as-ox leads to the isolation of a dinuclear compound where only one molecule of ligand has been added per two Mo atoms, Cp₂Mo₂Cl₄(as-ox). In the presence of free as-ox, this compound coexists with the paramagnetic mononuclear complex in solution. Both products are capable of controlling the radical polymerization of styrene under typical atom transfer radical polymerization (ATRP) conditions. However, the tacticity of the resulting polystyrene does not differ from that given by conventional free radical polymerization.     

A new North American therizinosaurid and the role of herbivory in ‘predatory’ dinosaur evolution

Historically, ecomorphological inferences regarding theropod (i.e. ‘predatory’) dinosaurs were guided by an assumption that they were singularly hypercarnivorous. A recent plethora of maniraptoran discoveries has produced evidence challenging this notion. Here, we report on a new species of maniraptoran theropod, Nothronychus graffami sp. nov. Relative completeness of this specimen permits a phylogenetic reassessment of Therizinosauria—the theropod clade exhibiting the most substantial anatomical evidence of herbivory. In the most comprehensive phylogenetic study of the clade conducted to date, we recover Therizinosauria as the basalmost maniraptoran lineage. Using concentrated changes tests, we present evidence for correlated character evolution among herbivorous and hypercarnivorous taxa and propose ecomorphological indicators for future interpretations of diet among maniraptoran clades. Maximum parsimony optimizations of character evolution within our study indicate an ancestral origin for dietary plasticity and facultative herbivory (omnivory) within the clade. These findings suggest that hypercarnivory in paravian dinosaurs is a secondarily derived dietary specialization and provide a potential mechanism for the invasion of novel morpho- and ecospace early in coelurosaurian evolution—the loss of obligate carnivory and origin of dietary opportunism.