A comparative protease stability study of synthetic macrocyclic peptides that mimic two endocrine hormones

Peptide therapeutics have traditionally faced many challenges including low bioavailability, poor proteolytic stability and difficult cellular uptake. Conformationally constraining the backbone of a peptide into a macrocyclic ring often ameliorates these problems and allows for the development of a variety of new drugs. Such peptide-based pharmaceuticals can enhance the multi-faceted functionality of peptide side chains, permitting the peptides to bind cellular targets and receptors necessary to impart their role, while protecting them from degrading cellular influences. In the work described here, we developed three cyclic peptides, VP mimic1, VP mimic2 and OT mimic1, which mimic endocrine hormones vasopressin and oxytocin. Making notable changes to the overall structure and composition of the parent hormones, we synthesized the mimics and tested their durability against treatment with three proteases chosen for their specificity: pepsin, alpha-chymotrypsin, and pronase. Vasopressin and oxytocin contain a disulfide linkage leaving them particularly vulnerable to deactivation from the reducing environment inside the cell. Thus, we increased the complexity of our assays by adding reducing agent glutathione to each mixture. Subsequently, we discovered each of our mimics withstood protease treatment with less degradation and/or a slower rate of degradation as compared to both parent hormones and a linear control peptide.     

Synthesis and biological evaluation against Leishmania amazonensis of a series of alkyl-substituted benzophenones

Nine O-alkyl and O-prenyl derivatives were synthesized from commercial 2,4-dihydroxybenzophenone, 4,e4,4′-dihydroxybenzophenone and were evaluated for their leishmanicidal activity against promastigote forms of Leishmania amazonensis, as well their toxicity in murine macrophages. All derivatives exhibited better biological activity than their hydroxylated benzophenones precursors, and new compound LFQM-123 (3c) was 250-fold more active than its precursor 4,4′-dihydroxybenzophenone (3). Moreover, some of the results were comparable to the standard drug Amphotericin B, suggesting that the increase in lipophilicity could facilitate protozoa membrane permeation. In this study we confirmed that benzophenone derivatives exhibit leishmanicidal properties, with relatively low toxicity, and thus could be exploited as promise prototypes for the design and development of new drug for the treatment of leishmaniasis.     

Does doping with aluminum alter the effects of ZnO nanoparticles on the metabolism of soil pseudomonads?

Doping of ZnO nanoparticles (NPs) is being used to increase their commercialization in the optical and semiconductor fields. This paper addresses whether doping with Al alters how ZnO NPs at nonlethal levels modifies the metabolism of soil-borne pseudomonads which are beneficial in performing bioremediation or promoting plant growth. The differences in X-ray diffraction (XRD) patterns, observed between commercial ZnO and Al-doped ZnO NPs indicated the aluminum was present as Al NPs. Both particles aggregated in the bacterial growth medium and formed colloids of different surface charges. They had similar effects on bacterial metabolism: rapid, dose-dependent loss in light output indicative of temporary toxicity in a biosensor constructed in Pseudomonas putida KT2440; increased production of a fluorescent pyoverdine-type siderophore, and decreased levels of indole acetic acid and phenazines in Pseudomonas chlororaphis O6. Solubilization of Zn and Al from the NPs contributed to these responses to different extents. These findings indicate that Al-doping of the ZnO NPs did not reduce the ability of the NPs to alter bacterial metabolism in ways that could influence performance of the pseudomonads in their soil environment.     

Degradation of chemical alarm cues and assessment of risk throughout the day

The use of chemical information in assessment of predation risk is pervasive across animal taxa. However, by its very nature, chemical information can be temporally unreliable. Chemical cues persist for some period of time after they are released into the environment. Yet, we know surprisingly little about the rate of degradation of chemical cues under natural conditions and hence little about how they function in temporal risk assessment under natural conditions. Here, we conducted an experiment to identify a concentration of fresh alarm cues that evoke a strong antipredator response in coral reef damselfish, Pomacentrus ambonensis. We then tested the rate at which these alarm cues degraded under natural conditions in ocean water, paying attention to whether the rate of degradation varied throughout the day and whether the temporal pattern correlated with physicochemical factors that could influence the rate of degradation. Fresh alarm cues released into ocean water evoke strong avoidance responses in juvenile fish, while those aged for 30 min no longer evoke antipredator responses. Fish exposed to cues aged for 10 or 20 min show intermediate avoidance responses. We found a marked temporal pattern of response throughout the day, with much faster degradation in early to mid‐afternoon, the time of day when solar radiation, temperature, dissolved oxygen, and pH are nearing their peak. Ecologists have spent considerable effort elucidating the role of chemical information in mediating predator–prey interactions, yet we know almost nothing about the temporal dynamics of risk assessment using chemical information. We are in dire need of additional comparative field experiments on the rate of breakdown of chemical cues, particularly given that global change in UV radiation, temperature, and water chemistry could be altering the rates of degradation and the potential use of this information in risk assessment.     

DCC Expression by Neurons Regulates Synaptic Plasticity in the Adult Brain

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Highlights? DCC and netrin-1 are enriched at synapses in the adult mouse forebrain ? DCC is enriched in the PSD and regulates dendritic spine morphology ? LTP induction and memory formation require DCC expression by neurons ? DCC activation of Src is required for NMDAR-dependent LTP in adult CNS     

Performance of Multiplex Cytokine Assays in Serum and Saliva among Community-Dwelling Postmenopausal Women

Multiplexing arrays increase the throughput and decrease sample requirements for studies employing multiple biomarkers. The goal of this project was to examine the performance of Multiplex arrays for measuring multiple protein biomarkers in saliva and serum. Specimens from the OsteoPerio ancillary study of the Women’s Health Initiative Observational Study were used. Participants required the presence of at least 6 teeth and were excluded based on active cancer and certain bone issues but were not selected on any specific condition. Quality control (QC) samples were created from pooled serum and saliva. Twenty protein markers were measured on five multiplexing array panels. Sample pretreatment conditions were optimized for each panel. Recovery, lower limit of quantification (LLOQ) and imprecision were determined for each analyte. Statistical adjustment at the plate level was used to reduce imprecision estimates and increase the number of usable observations. Sample pre-treatment improved recovery estimates for many analytes. The LLOQ for each analyte agreed with manufacturer specifications except for MMP-1 and MMP-2 which were significantly higher than reported. Following batch adjustment, 17 of 20 biomarkers in serum and 9 of 20 biomarkers in saliva demonstrated acceptable precision, defined as <20% coefficient of variation (<25% at LLOQ). The percentage of cohort samples having levels within the reportable range for each analyte varied from 10% to 100%. The ratio of levels in saliva to serum varied from 1∶100 to 28∶1. Correlations between saliva and serum were of moderate positive magnitude and significant for CRP, MMP-2, insulin, adiponectin, GM-CSF and IL-5. Multiplex arrays exhibit high levels of analytical imprecision, particularly at the batch level. Careful sample pre-treatment can enhance recovery and reduce imprecision. Following statistical adjustments to reduce batch effects, we identified biomarkers that are of acceptable quality in serum and to a lesser degree in saliva using Multiplex arrays.