Identification of spirocyclic piperidine-azetidine inverse agonists of the ghrelin receptor

The discovery of spirocyclic piperidine-azetidine inverse agonists of the ghrelin receptor is described. The characterization and redressing of the issues associated with these compounds is detailed. An efficient three-step synthesis and a binding assay were relied upon as the primary means of rapidly improving potency and ADMET properties for this class of inverse agonist compounds. Compound 10 n bearing distributed polarity in the form of an imidazo-thiazole acetamide and a phenyl triazole is a unit lower in logP and has significantly improved binding affinity compared to the hit molecule 10a, providing support for further optimization of this series of compounds.     

Did pollination shifts drive diversification in southern African Gladiolus? Evaluating the model of pollinator-driven speciation

The pollinator-driven ecological speciation model has frequently been invoked to explain plant richness in biodiversity hotspots. Here, by focusing on Gladiolus (260 species), a flagship example of a clade with diverse pollination biology, we test the hypothesis that high species diversity in southern Africa, one of the world's most floristically rich regions, has primarily been driven by ecological shifts in pollination systems. We use phylogenetic methods to estimate rates of transition between the seven highly specialized pollination strategies in Gladiolus. We find that pollination systems have evolved multiple times and that some pollination strategies arose by a variety of evolutionary pathways. Pollination shifts account for up to one-third of all lineage splitting events in the genus, providing partial support for the pollinator-driven speciation model. Transitions from the ancestral pollination mode to derived systems have also resulted in increased rates of diversification, suggesting that certain pollination systems may speed up speciation processes, independently of pollination shifts per se. This study suggests that frequent pollination shifts have played a role in driving high phenotypic and species diversity but indicates that additional factors need to be invoked to account for the spectacular diversification in southern African Gladiolus.     

An in vitro fluid dynamic study of pediatric cannulae: the value of animal studies to predict human flow

A challenge to the development of pediatric ventricular assist devices (PVADs) is the use of the aortic cannulae attached to the devices. Cannulae used for pediatric application have small diameters and large pressure drops. Furthermore, during the development of the 12cc Penn State pediatric PVAD, particle image velocimetry (PIV) illustrated that hematocrit levels, through changes in blood viscoelasticity, affected the fluid dynamics. The objective of this study is to compare the fluid dynamics of a pediatric viscoelastic blood analog and a goat viscoelastic blood analog within the PVAD aortic cannula. Two acrylic models were manufactured to model the aortic cannula (6 mm and 8 mm diameters). PIV data was collected to examine the flow at the outlet of the VAD and in the aortic cannula at heart rates of 50 and 75 beats per minute (bpm). Three planes of data were taken, one at the centerline and two 1.5 mm above and below the centerline. Three more planes of data were taken orthogonal to the original planes. While a 75 bpm heart rate was used to represent normal operating conditions, a 50 bpm heart rate represented use of the PVAD during weaning. At 75 bpm, differences were evident between the two different fluids and the two models. Separation zones developed in the plane below the centerline for the higher hematocrit pediatric blood analog. This study raises question to the usefulness of animal testing results in regard to how well they predict the outcome of pediatric patients.     

Abiotic drivers and plant traits explain landscape‐scale patterns in soil microbial communities

The controls on aboveground community composition and diversity have been extensively studied, but our understanding of the drivers of belowground microbial communities is relatively lacking, despite their importance for ecosystem functioning. In this study, we fitted statistical models to explain landscape‐scale variation in soil microbial community composition using data from 180 sites covering a broad range of grassland types, soil and climatic conditions in England. We found that variation in soil microbial communities was explained by abiotic factors like climate, pH and soil properties. Biotic factors, namely community‐weighted means (CWM) of plant functional traits, also explained variation in soil microbial communities. In particular, more bacterial‐dominated microbial communities were associated with exploitative plant traits versus fungal‐dominated communities with resource‐conservative traits, showing that plant functional traits and soil microbial communities are closely related at the landscape scale.     

Antipsychotic treatment of acute paranoid schizophrenia patients with olanzapine results in altered glycosylation of serum glycoproteins

Atypical antipsychotic drugs, such as olanzapine, have been shown to alleviate the positive, negative and, to a lesser degree, the cognitive symptoms of schizophrenia in many patients. However, the detailed mechanisms of action of these drugs have yet to be elucidated. We have carried out the first investigation aimed at evaluating the effects of olanzapine treatment on the glycosylation of serum proteins in schizophrenia patients. Olanzapine treatment resulted in increased levels of a disialylated biantennary glycan and reduced levels of a number of disialylated bi- and triantennary glycans on whole serum glycoproteins. These changes were not observed on a low-abundance serum protein fraction. α1 acid glycoprotein was identified as a carrier of some of the detected altered oligosaccharides. In addition, glycan analysis of haptoglobin, transferrin, and α1 antitrypsin reported similar findings, although these changes did not reach significance. Exoglycosidase digestion analysis showed that olanzapine treatment increased galactosylation and sialylation of whole serum proteins, suggesting increased activity of specific galactosyltransferases and increased availability of galactose residues for sialylation. Taken together, these findings indicate that olanzapine treatment results in altered glycosylation of serum proteins.     

Regional cell shape changes control form and function of Kupffer's vesicle in the zebrafish embryo

Cilia-generated fluid flow in an 'organ of asymmetry' is critical for establishing the left-right body axis in several vertebrate embryos. However, the cell biology underlying how motile cilia produce coordinated flow and asymmetric signals is not well defined. In the zebrafish organ of asymmetry-called Kupffer's vesicle (KV)-ciliated cells are asymmetrically positioned along the anterior-posterior axis such that more cilia are placed in the anterior region. We previously demonstrated that Rho kinase 2b (Rock2b) is required for anteroposterior asymmetry and fluid flow in KV, but it remained unclear how the distribution of ciliated cells becomes asymmetric during KV development. Here, we identify a morphogenetic process we refer to as 'KV remodeling' that transforms initial symmetry in KV architecture into anteroposterior asymmetry. Live imaging of KV cells revealed region-specific cell shape changes that mediate tight packing of ciliated cells into the anterior pole. Mathematical modeling indicated that different interfacial tensions in anterior and posterior KV cells are involved in KV remodeling. Interfering with non-muscle myosin II (referred to as Myosin II) activity, which modulates cellular interfacial tensions and is regulated by Rock proteins, disrupted KV cell shape changes and the anteroposterior distribution of KV cilia. Similar defects were observed in Rock2b depleted embryos. Furthermore, inhibiting Myosin II at specific stages of KV development perturbed asymmetric flow and left-right asymmetry. These results indicate that regional cell shape changes control the development of anteroposterior asymmetry in KV, which is necessary to generate coordinated asymmetric fluid flow and left-right patterning of the embryo.     

A Method of Moments Estimator for Random Effect Multivariate Meta‐Analysis

Summary Meta‐analysis is a powerful approach to combine evidence from multiple studies to make inference about one or more parameters of interest, such as regression coefficients. The validity of the fixed effect model meta‐analysis depends on the underlying assumption that all studies in the meta‐analysis share the same effect size. In the presence of heterogeneity, the fixed effect model incorrectly ignores the between‐study variance and may yield false positive results. The random effect model takes into account both within‐study and between‐study variances. It is more conservative than the fixed effect model and should be favored in the presence of heterogeneity. In this paper, we develop a noniterative method of moments estimator for the between‐study covariance matrix in the random effect model multivariate meta‐analysis. To our knowledge, it is the first such method of moments estimator in the matrix form. We show that our estimator is a multivariate extension of DerSimonian and Laird’s univariate method of moments estimator, and it is invariant to linear transformations. In the simulation study, our method performs well when compared to existing random effect model multivariate meta‐analysis approaches. We also apply our method in the analysis of a real data example.     

Characterization of the solution conformations of leuprolide acetate.

Leuprolide acetate (pGlu-His-Trp-Ser-Tyr-d-Leu-Leu-Arg-Pro-NHEt), a potent LHRH agonist in wide clinical use, was characterized conformationally by NMR and circular dichroism. It displayed quite different preferred conformations under different solution conditions: two low population beta-turns in water, a nascent helix in TFE/water at low pH, and a high population beta-turn in TFE/water at slightly acidic pH. The pH-related conformational change in TFE/water is attributed to the pK(a) of the acetate counterion, not to ionizable groups on the peptide. None of these conformations are in exact agreement with previous computational predictions.     

Enriching small trees with artificial nest boxes cannot mimic the value of large trees for hollow‐nesting birds

Large trees support unique habitat structures (e.g. hollows) that form over centuries and cannot be provided by small trees. Large trees are also declining in human‐modified landscapes worldwide. One restoration strategy gaining popularity involves adding nest boxes to smaller trees to replicate natural hollows. However, limited empirical research has tested how hollow‐nesting fauna responds to the presence of nest boxes. We asked: can the addition of nest boxes increase tree visitation by hollow‐nesting birds? We conducted a before‐after control‐impact (BACI) experiment using 144 nest boxes and 96 sample trees comprised of three sizes (small [20–50 cm dbh], medium [51–80 cm], and large [>80 cm]) and located in four landscape contexts (reserves, pasture, urban parklands, and urban built‐up areas). We recorded a significant increase in hollow‐nesting bird abundance and richness at large trees after nest box additions. However, the same response was not observed at medium, small, or control trees. We also recorded nonsignificant increases in hollow‐nesting bird abundance and richness at trees in modified landscapes after nest box additions compared to trees in reserves and control trees. Our results suggest that adding nest boxes to smaller‐sized trees may not attract hollow‐nesting birds. Therefore, nest box management strategies may require re‐evaluation as it is often assumed that hollow supplementation will attract hollow‐using fauna and sufficiently ameliorate the loss of large, hollow‐bearing trees. We advocate that large tree retention remains crucial and should be prioritized. Large trees could be effective target structures for habitat restoration, especially in modified landscapes.     

Estimating dinosaur maximum running speeds using evolutionary robotics

Maximum running speed is an important locomotor parameter for many animals-predators as well as prey-and is thus of interest to palaeobiologists wishing to reconstruct the behavioural ecology of extinct species. A variety of approaches have been tried in the past including anatomical comparisons, bone scaling and strength, safety factors and ground reaction force analyses. However, these approaches are all indirect and an alternative approach is to create a musculoskeletal model of the animal and see how fast it can run. The major advantage of this approach is that all assumptions about the animal's morphology and physiology are directly addressed, whereas the exact same assumptions are hidden in the indirect approaches. In this paper, we present simple musculoskeletal models of three extant and five extinct bipedal species. The models predict top speed in the extant species with reasonably good agreement with accepted values, so we conclude that the values presented for the five extinct species are reasonable predictions given the modelling assumptions made. Improved musculoskeletal models and better estimates of soft tissue parameters will produce more accurate values. Limited sensitivity analysis is performed on key muscle parameters but there is considerable scope for extending this in the future.