Positive allosteric modulators of the α7 nicotinic acetylcholine receptor: SAR investigation around PNU-120596.

The α7 nicotinic acetylcholine receptor is a calcium permeable, ligand-gated ion channel that modulates synaptic transmission in the hippocampus, thalamus, and cerebral cortex. Previously disclosed work described PNU-120596 that acts as a powerful positive allosteric modulator of the α7 nicotinic acetylcholine receptor. The initial structure-activity relationships around PNU-120596 were gleaned from screening a large thiazole library. Independent systematic examination of the aryl and heteroaryl groups resulted in compounds with enhanced potency and improved physico-chemical properties culminating in the identification of 16 (PHA-758454). In the presence of acetylcholine, 16 enhanced evoked currents in rat hippocampal neurons. In a rat model of impaired sensory gating, treatment with 16 led to a reversal of the gating deficit in a dose-dependent manner. These results demonstrate that aryl heteroaryl ureas, like compound 16, may be useful tools for continued exploration of the unique biology of the α7 nicotinic acetylcholine receptor.

Top-down effects of raptor predation on northern bobwhite.

Understanding how predators affect prey species is a central endeavor in applied ecology. Game birds are a culturally and economically important group of birds throughout the world. Specifically, northern bobwhite (Colinus virginianus) is an imperiled game bird native to North America that has declined precipitously over the past 65 years. Concurrently, raptor populations increased substantially as a result of pesticide bans and legal protections. However, relationships between raptors and bobwhites are not well-understood because of limited long-term data. We analyzed long-term raptor survey and bobwhite survival datasets from 2008 to 2018 to determine if oscillations in raptor abundance affected bobwhite survival. We used a novel open multi-species dynamics hierarchical distance sampling model to estimate the abundance of raptors. We used a known-fate survival model to determine if variation in raptor abundance affected bobwhite survival. We had multiple working hypotheses regarding biological relationships between raptor abundance and bobwhite survival. Raptors affected bobwhites in every biological season but were more influential in the breeding season and late winter supporting the notion of bobwhite behavior and raptor migration were driving observed patterns. Our results suggest that even in areas with abundant habitat, predators exert top-down influences on vital rates suggesting similar or greater influences on populations under poor habitat conditions.

Modulation of TARP γ8-Containing AMPA Receptors as a Novel Therapeutic Approach for Chronic Pain.

Nonselective glutamate α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor antagonists are efficacious in chronic pain but have significant tolerability issues, likely arising from the ubiquitous expression of AMPA receptors in the central nervous system (CNS). Recently, LY3130481 has been shown to selectively block AMPA receptors coassembled with the auxiliary protein, transmembrane AMPA receptor regulatory protein (TARP) γ8, which is highly expressed in the hippocampus but also in pain pathways, including anterior cingulate (ACC) and somatosensory cortices and the spinal cord, suggesting that selective blockade of γ8/AMPA receptors may suppress nociceptive signaling with fewer CNS side effects. The potency of LY3130481 on recombinant γ8-containing AMPA receptors was modulated by coexpression with other TARPs; γ2 subunits affected activity more than γ3 subunits. Consistent with these findings, LY3130481 had decreasing potency on receptors from rat hippocampal, cortical, spinal cord, and cerebellar neurons that was replicated in tissue from human brain. LY3130481 partially suppressed, whereas the nonselective AMPA antagonist GYKI53784 completely blocked, AMPA receptor-dependent excitatory postsynaptic potentials in ACC and spinal neurons in vitro. Similarly, LY3130481 attenuated short-term synaptic plasticity in spinal sensory neurons in vivo in response to stimulation of peripheral afferents. LY3130481 also significantly reduced nocifensive behaviors after intraplantar formalin that was correlated with occupancy of CNS γ8-containing AMPA receptors. In addition, LY3130481 dose-dependently attenuated established gait impairment after joint damage and tactile allodynia after spinal nerve ligation, all in the absence of motor side effects. Collectively, these data demonstrate that LY3130481 can suppress excitatory synaptic transmission and plasticity in pain pathways containing γ8/AMPA receptors and significantly reduce nocifensive behaviors, suggesting a novel, effective, and safer therapy for chronic pain conditions.

Influence of decompression sickness on vasomotion of isolated rat vessels.

Several studies have demonstrated that endothelial function is impaired following a dive even without decompression sickness. During this study we determined the effect of decompression sickness on endothelium-dependent and independent vasoreactivity. For this purpose twenty-seven male Sprague-Dawley rats were submitted to a simulated dive up to 1,000 kPa absolute pressure and divided into 3 groups: safe diving without decompression sickness or dives provoking mild or severe sickness. A fourth control group remained at atmospheric pressure. Endothelium-dependent and independent vasomotion was assessed ex vivo by measuring isometric tension in rings of abdominal aorta and mesenteric arteries. Dose-response curves were obtained with phenylephrine, acetylcholine and sodium nitroprusside. Acetylcholine-induced relaxation was measured in the presence of L-NAME, indometacin or both of them at once.Contraction was significantly decreased after each protocol compared with the control rats. Additionally, the response in animals from the severe group was significantly different from that of the safe and mild groups. Dose response curves for acetylcholine alone and in the presence of inhibitors remained unchanged. We did not observe differences in endothelium-dependent vasodilation after diving or in the presence of decompression sickness. Contractile response to phenylephrine was progressively impaired with increased decompression stress. These results may indicate smooth muscle injury.

Comparison of Sodium Selenite and Selenium-Enriched Spirulina Supplementation Effects After Selenium Deficiency on Growth, Tissue Selenium Concentrations, Antioxidant Activities, and Selenoprotein Expression in Rats.

Selenium contributes to physiological functions through its incorporation into selenoproteins. It is involved in oxidative stress defense. A selenium deficiency results in the onset or aggravation of pathologies. Following a deficiency, the repletion of selenium leads to a selenoprotein expression hierarchy misunderstood. Moreover, spirulina, a microalga, exhibits antioxidant properties and can be enriched in selenium.. Our objective was to determine the effects of a sodium selenite or selenium-enriched spirulina supplementation. Thirty-two female Wistar rats were fed for 12 weeks with a selenium-deficient diet. After 8 weeks, rats were divided into 4 groups and were fed with water, sodium selenite (20 µg Se/kg body weight), spirulina (3 g/kg bw), or selenium-enriched spirulina (20 µg Se/kg bw + 3 g spirulina/kg bw). Another group of 8 rats was fed with normal diet during 12 weeks. Selenium concentration and antioxidant enzyme activities were measured in plasma, urine, liver, brain, kidney, heart, and soleus. Expression of GPx (1, 3), Sel (P, S, T, W), SEPHS2, TrxR1, ApoER2, and megalin were quantified in liver, kidney, brain, and heart. We showed that a selenium deficiency leads to a growth delay, reversed by selenium supplementation despite a minor loss of weight in week 12 for SS rats. All tissues displayed a decrease in selenium concentration following deficiency. The brain seemed protected. We demonstrated a hierarchy in selenium distribution and selenoprotein expression. A supplementation of sodium selenite improved GPx activities and selenoprotein expression while a selenium-enriched spirulina was more effective to restore selenium concentration especially in the liver, kidney, and soleus.

Active forest stewardship benefits priority birds in the New Jersey Pine Barrens.

Fire suppression has negatively impacted thousands of acres of private and public lands in the United States. As a case study, the New Jersey Pine Barrens (NJPB) are a disturbance driven ecosystem that is experiencing serious ecological implications due to a loss of traditional forest thinning activities such as harvesting for forest products or thinning for wildfire fuel-load reduction measures coupled with a long-standing philosophy of fire suppression and dormant-season prescribed burning. Dense closed-canopy forest conditions, dissimilar to historic open-canopy forests of the NJPB, have reduced abundance and diversity of certain flora and fauna, including regionally imperiled breeding birds. In recent years, active forest stewardship (e.g., thinning, clear-cutting, and burning) has occurred on private and some public lands within the NJPB; however, the impact of such management on breeding birds is unclear due to a paucity of research on this subject within the NJPB. During 2012, 2013, 2016, and 2017, we conducted repeat-visit point counts (n = 1,800) for breeding songbirds across 75 control and 75 treatment sites within the NJPB to assess the influence of forest structure at three strata levels (groundcover, midstory profile, and canopy) on breeding bird communities. Specifically, we constructed a hierarchical community abundance model within a Bayesian framework for Bird Conservation Region (BCR) 30 priority upland birds (n = 12) within three species suites: Forested Upland, Scrub-Shrub (or Young Forest), and Grassland. At the community level, we found a negative relationship between bird abundance and live tree basal area. At the BCR 30 suite level, we found no relationship between Forested Upland suite-level abundance and any of the measured covariates; however, we found a negative relationship between percentage of woody groundcover and Scrub-Shrub suite-level abundance, and negative relationship between horizontal visual obstruction at 2 m above ground level and Grassland suite-level abundance. Furthermore, the two latter species suites exhibited a strong negative relationship with basal area. We recommend active forest stewardship that specifically targets opening the canopy to achieve basal areas between ~0-15 m2/ha via selective thinning, shelter cutting, and small-scale clear cutting. Mechanical treatment and prescribed burning would produce such conditions and have the added benefit of reducing fuel loads across this ~4,500 km2 landscape as well as assisting in carbon defense strategies for the region.

Temporal and scalar variations affect resource use of northern bobwhite broods.

Disparate resource use originating from phenology of biotic resources, abiotic conditions, and life cycles of exploiting organisms underscores the importance of research across time and space to guide management practices. Our goal was to evaluate resource use of northern bobwhite (Colinus virginianus; bobwhite) at two spatial scales and across three age classes, from hatching through a period of the postjuvenile molt. Our study was conducted at Tall Timbers Research Station, Tallahassee, FL, USA-situated in a landscape subjected to small scale (<20 ha) prescribed fires on a 2-year fire rotation. We predicted prescribed fire, disking, and supplemental feeding would dictate resource use, but effects would depend on time since fire, brood age, and time of day. We predicted vegetation and temperature would govern roost use by broods, but these effects would also depend on age. We radio-tracked 62 broods 21-35 times / week during May-October 2018 and 2019. Broods were less likely to use areas with large proportions of hardwood drains but favored sites with greater proportions of burned uplands, regardless of the time of day. Broods were less likely to use areas at greater distances from supplemental feed; this relationship had no interaction with age but was stronger later in the nesting season (>July 15). Broods were more likely to use areas with greater proportions of fallow fields during the day than for roosting. Broods used roosts with more woody cover and visual obscurity than at available sites. Roosts consisted of less grass and bare ground. However, these effects interacted with age; broods used sparser cover at older ages. Neonate broods were more likely to use cooler roosts with greater thermal stability, but this effect was reversed for juveniles. Broods may alter resource use with changes in vulnerabilities to threats such as thermal risks and predation.

Translocation to a fragmented landscape: survival, movement, and site fidelity of Northern Bobwhites.

Habitat fragmentation, degradation, and loss have taxed early-successional species including the Northern Bobwhite (Colinus virginianus) and numerous grassland obligate birds. Translocation is often applied to counteract the consequences of habitat fragmentation through the creation, reestablishment, or augmentation of wild populations for the purposes of conservation, biodiversity maintenance. However, the implementation of these techniques is often conducted without valid experimental designs and therefore lacks robust, empirical data needed to evaluate and advance the knowledge and application of translocation. Despite the increasing amount of habitat management applied to patches among fragmented landscapes, a paucity of source populations often limits natural (re)colonization. As such, translocation may serve as a surrogate to natural dispersal, but its efficacy among fragmented landscapes is uncertain. Few studies exist that have assessed site fidelity, movement, and survival of individuals following translocation among fragmented landscapes. Thus, we experimentally evaluated the efficacy of translocation using known-fate and multi-strata models to evaluate hypotheses of temporal, biological, and group effects on survival and movement of translocated and resident bobwhites. We did not detect differences in survival or movement between translocated and resident bobwhites, suggesting that movement of individuals to a fragmented habitat does not negatively influence these demographic attributes. Based on these data, we suggest that two site-specific criteria should be met prior to instituting translocation: habitat management should be conducted to ensure that quality habitat exists and the patch size should be a minimum of 600 ha of quality habitat (poorer sites may warrant even larger patches). Translocation is a viable conservation method for increasing abundance in patches when habitat quality is high but source populations are limited.

Measuring the biological impact of drilling waste on the deep seafloor: An experimental challenge.

The depletion of traditional oil fields is driving the oil & gas industry to explore new exploitation sites previously considered as unprofitable. Deep-sea oil fields represent one of these new areas of exploitation. Well drilling during exploration and production operations generate large quantities of drilling waste whose biological impact on the deep-sea floor remains largely unknown. Because of the harsh abiotic factors characterizing this environment, the evaluation of this impact remains challenging. High hydrostatic pressure is the prominent factor which will affect in-situ biological processes. This review will examine the feedback on the various strategies used to evaluate the biological impact of deep-sea drilling waste deposition as well as the current technological limitations. Given the complexity of this issue, a good perspective strategy would be to trend towards the research and development of more relevant bioassays, especially considering the crucial factor of hydrostatic pressure.

Validation of a noninvasive technique to quantify stress in northern bobwhite (Colinus virginianus).

Examination of the endocrine system through non-invasive fecal sampling may improve population management more than using demographic indicators alone. By addressing the physiological mechanisms that are influencing fitness, management actions can be proactively developed to alleviate stressors. Proactive determination of vulnerable populations is critical for species of concern, such as the Northern Bobwhite (Colinus virginianus), which have suffered decades of population decline. We validated an assay to noninvasively measure the adrenocortical response of captive reared bobwhite through fecal corticosterone metabolites (FCM). All individuals received three sequential 48-hour treatments in which samples were collected every 4 hours, including a reference period, an adrenocorticotropic hormone (ACTH) challenge and a biological stressor (exposure to a hunting dog). Reference FCM values had a mean concentration of 16.75 pg/mg (95% CrI: 13.68, 19.91) with adrenocortical activity increasing by 73% for the duration of the ACTH challenge (29.00 pg/mg; CrI: 25.01, 33.78). FCM concentrations remained similar to that of the reference levels during the biological stressor (16.56 pg/mg; CrI: 13.33, 19.92). Our study validates the use of feces to detect changes in FCM levels in our subject species but also demonstrates the complexity of FCM and the importance of both physiological and biological validation prior to field implementation.

A clinically relevant and bias-controlled murine model to study acute traumatic coagulopathy.

Acute traumatic coagulopathy (ATC) is an acute and endogenous mechanism triggered by the association of trauma and hemorrhage. Several animal models have been developed, but some major biases have not yet been identified. Our aim was to develop a robust and clinically relevant murine model to study this condition. Anesthetized adult Sprague Dawley rats were randomized into 4 groups: C, control; T, trauma; H, hemorrhage; TH, trauma and hemorrhage (n = 7 each). Trauma consisted of laparotomy associated with four-limb and splenic fractures. Clinical variables, ionograms, arterial and hemostasis blood tests were compared at 0 and 90 min. ATC and un-compensated shock were observed in group TH. In this group, the rise in prothrombin time and activated partial thromboplastin was 29 and 40%, respectively. Shock markers, compensation mechanisms and coagulation pathways were all consistent with human pathophysiology. The absence of confounding factors, such as trauma-related bleeding or dilution due to trans-capillary refill was verified. This ethic, cost effective and bias-controlled model reproduced the specific and endogenous mechanism of ATC and will allow to identify potential targets for therapeutics in case of trauma-related hemorrhage.

Microbial composition in bioaerosols of a high-throughput chicken-slaughtering facility.

The microbial composition of the air in various areas of a high-throughput chicken-slaughtering facility was investigated. Over a 4-mo period, 6 processing areas were sampled, and the influence of environmental factors was monitored. The highest counts of microorganisms were recorded in the initial stages of processing, comprising the receiving-killing and defeathering areas, whereas counts decreased toward the evisceration, air-chilling, packaging, and dispatch areas. Maximum microbial counts were as follows: coliforms, 4.9 x 10(3) cfu/m(3); Escherichia coli 3.4 x 10(3) cfu/m(3); Bacillus cereus, 5.0 x 10(4) cfu/m(3); Staphylococcus aureus, 1.6 x 10(4) cfu/m(3); Pseudomonas aeruginosa, 7.0 x 10(4) cfu/m(3); presumptive Salmonella spp., 1.5 x 10(4) cfu/m(3); Listeria monocytogenes, 1.6 x 10(4) cfu/m(3); and fungi, 1.4 x 10(4) cfu/m(3). Higher counts of airborne microorganisms found in the receiving-killing and defeathering areas indicate the importance of controlling microbial levels before processing to prevent the spread of organisms downstream. This should limit the risk of carrying over contaminants from areas known to generate high counts to areas where the final food product is exposed to air and surface contamination.

Process-Structure Linkages Using a Data Science Approach: Application to Simulated Additive Manufacturing Data.

A novel data science workflow is developed and demonstrated to extract process-structure linkages (i.e., reduced-order model) for microstructure evolution problems when the final microstructure depends on (simulation or experimental) processing parameters. This workflow consists of four main steps: data pre-processing, microstructure quantification, dimensionality reduction, and extraction/validation of process-structure linkages. Methods that can be employed within each step vary based on the type and amount of available data. In this paper, this data-driven workflow is applied to a set of synthetic additive manufacturing microstructures obtained using the Potts-kinetic Monte Carlo (kMC) approach. Additive manufacturing techniques inherently produce complex microstructures that can vary significantly with processing conditions. Using the developed workflow, a low-dimensional data-driven model was established to correlate process parameters with the predicted final microstructure. Additionally, the modular workflows developed and presented in this work facilitate easy dissemination and curation by the broader community.

A novel positive allosteric modulator of the alpha7 neuronal nicotinic acetylcholine receptor: in vitro and in vivo characterization.

Several lines of evidence suggest a link between the alpha7 neuronal nicotinic acetylcholine receptor (nAChR) and brain disorders including schizophrenia, Alzheimer's disease, and traumatic brain injury. The present work describes a novel molecule, 1-(5-chloro-2,4-dimethoxy-phenyl)-3-(5-methyl-isoxazol-3-yl)-urea (PNU-120596), which acts as a powerful positive allosteric modulator of the alpha7 nAChR. Discovered in a high-throughput screen, PNU-120596 increased agonist-evoked calcium flux mediated by an engineered variant of the human alpha7 nAChR. Electrophysiology studies confirmed that PNU-120596 increased peak agonist-evoked currents mediated by wild-type receptors and also demonstrated a pronounced prolongation of the evoked response in the continued presence of agonist. In contrast, PNU-120596 produced no detectable change in currents mediated by alpha4beta2, alpha3beta4, and alpha9alpha10 nAChRs. PNU-120596 increased the channel mean open time of alpha7 nAChRs but had no effect on ion selectivity and relatively little, if any, effect on unitary conductance. When applied to acute hippocampal slices, PNU-120596 increased the frequency of ACh-evoked GABAergic postsynaptic currents measured in pyramidal neurons; this effect was suppressed by TTX, suggesting that PNU-120596 modulated the function of alpha7 nAChRs located on the somatodendritic membrane of hippocampal interneurons. Accordingly, PNU-120596 greatly enhanced the ACh-evoked inward currents in these interneurons. Systemic administration of PNU-120596 to rats improved the auditory gating deficit caused by amphetamine, a model proposed to reflect a circuit level disturbance associated with schizophrenia. Together, these results suggest that PNU-120596 represents a new class of molecule that enhances alpha7 nAChR function and thus has the potential to treat psychiatric and neurological disorders.

Discovery of N-[(3R)-1-azabicyclo[2.2.2]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide, an agonist of the alpha7 nicotinic acetylcholine receptor, for the potential treatment of cognitive deficits in schizophrenia: synthesis and structure--activity relationship.

N-[(3R)-1-Azabicyclo[2.2.2]oct-3-yl]furo[2,3-c]pyridine-5-carboxamide (14, PHA-543,613), a novel agonist of the alpha7 neuronal nicotinic acetylcholine receptor (alpha7 nAChR), has been identified as a potential treatment of cognitive deficits in schizophrenia. Compound 14 is a potent and selective alpha7 nAChR agonist with an excellent in vitro profile. The compound is characterized by rapid brain penetration and high oral bioavailability in rat and demonstrates in vivo efficacy in auditory sensory gating and, in an in vivo model to assess cognitive performance, novel object recognition.

A quantitative model of error accumulation during PCR amplification.

The amplification of target DNA by the polymerase chain reaction (PCR) produces copies which may contain errors. Two sources of errors are associated with the PCR process: (1) editing errors that occur during DNA polymerase-catalyzed enzymatic copying and (2) errors due to DNA thermal damage. In this study a quantitative model of error frequencies is proposed and the role of reaction conditions is investigated. The errors which are ascribed to the polymerase depend on the efficiency of its editing function as well as the reaction conditions; specifically the temperature and the dNTP pool composition. Thermally induced errors stem mostly from three sources: A+G depurination, oxidative damage of guanine to 8-oxoG and cytosine deamination to uracil. The post-PCR modifications of sequences are primarily due to exposure of nucleic acids to elevated temperatures, especially if the DNA is in a single-stranded form. The proposed quantitative model predicts the accumulation of errors over the course of a PCR cycle. Thermal damage contributes significantly to the total errors; therefore consideration must be given to thermal management of the PCR process.

Discovery and structure-activity relationship of quinuclidine benzamides as agonists of alpha7 nicotinic acetylcholine receptors.

A library of benzamides was tested for alpha7 nicotinic acetylcholine receptor (nAChR) agonist activity using a chimeric receptor in a functional, cell-based, high-throughput assay. From this library, quinuclidine benzamides were found to have alpha7 nAChR agonist activity. The SAR diverged from the activity of this compound class verses the 5-HT(3) receptor, a structural homologue of the alpha7 nAChR. PNU-282987, the most potent compound from this series, was also shown to open native alpha7 nAChRs in cultured rat neurons and to reverse an amphetamine-induced gating deficit in rats.

The RU5 ('R') region from human leukaemia viruses (HTLV-1) contains an internal ribosome entry site (IRES)-like sequence.

RNA fragments containing the complete R region and the beginning of the U5 region ('R') from the human T cell leukaemia virus 1 (HTLV-1) stimulated the translation of the second cistrons in bicistronic mRNAs. The 5' untranslated region from SV40 early genes (SU) which was unable to stimulate translation of second cistrons amplified markedly the internal ribosome entry site (IRES) effect of the HTLV-1 'R' fragments. The 'R' regions from HTLV-1 have therefore properties similar to internal ribosome entry sites (IRES) originally found in picornavirus. The beginning of the U5 region from HTLV-1 contains a polypyrimidine sequence which is known to play an essential role in the IRES activity in picornavirus. The same experiments carried out using the 'R' region from bovine leukaemia virus (BLV) showed that this sequence has at most a weak IRES effect. One retroviruses, HTLV-1 and perhaps others contain therefore an IRES activity. Interestingly, the combined SU 'R' sequence worked efficiently with different cistrons, different promoters and in all tested cell lines, whereas the poliovirus IRES was active in CHO cells but not in the mouse mammary cell line HC11. The SU 'R' sequence may therefore preferably be used to generate active bicistronic mRNAs.

A distal region enhances the prolactin induced promoter activity of the rabbit alpha s1-casein gene.

Casein gene expression is induced in the rabbit mammary gland by prolactin (PRL). alpha s1-casein is the major casein secreted into milk. In order to define the position of the DNA sequences involved in the control of rabbit alpha s1-casein gene regulation by PRL, chimeric genes were constructed between upstream regions of the rabbit alpha s1-casein gene and the chloramphenicol acetyl transferase (CAT) reporter gene. A series of 5'-deleted fusion genes was obtained by nuclease digestion of the alpha s1-casein gene upstream region. These gene constructs were transfected into rabbit primary mammary cells, or cotransfected in CHO cells with the plasmid coding for the rabbit mammary receptor (PRL-R). A regulatory region has been located between nt -3768 and -3155. This region enhances the prolactin induced promoter activity of the alpha s1-casein gene. It might possess or cooperate with prolactin responsive elements located further downstream in the alpha s1-casein gene.

Why can the eel, unlike the trout, migrate under pressure.

In order to elucidate the difference between pressure resistance in trout (Onchorhyncus mykiss) and eel (Anguilla anguilla), oxygen consumption of red muscle permeabilised cells and mitochondria were measured at 101 ATA hydrostatic pressure per se. Such an experiment involved the setting up of a special system allowing measurements under high pressure. The results show that hydrostatic pressure strongly alters the oxidative phosphorylation in trout but not in eel, which exhibits mitochondrial pressure resistance. It is hypothesised that the eel has a supranormal mitochondria functioning at atmospheric pressure in order to cope with the high pressure environment encountered during its migration.