Evaluating and predicting risk to a large reptile (Varanus varius) from feral cat baiting protocols

Control of introduced predators to mitigate biodiversity impacts is a pressing conservation challenge. Across Australia feral cats (Felis catus) are a major threat to terrestrial biodiversity. Currently feral cat control is hindered by the limited utility of existing predator baiting methods. Further proposed control methods include use of the novel poison para-aminopropiophenone (PAPP) which may present a hazard to some native animal populations. Here we used experimental and predictive approaches to evaluate feral cat bait take by a large native Australian predatory reptile the Lace monitor (Varanus varius). These lizards would be expected to readily detect, ingest and consume a lethal dose (depending on toxin) from surface-laid baits intended for feral cat control if a precautionary approach was not adopted when baiting. We modelled V. varius bait take using experimental and predictive biophysical modelling approaches to evaluate temporal effects of climate variables on V. varius activity and hence potential for bait removal. Finally we conducted a pre-PAPP baiting site occupancy assessment of V. varius within Wilson Promontory National Park (WPNP) to provide a basis for monitoring any longer term population effects of cat baiting. V. varius removed 7 % of deployed baits from 73 % of bait stations across another study area in Far Eastern Victoria. Daily bait removal was positively correlated with maximum temperature and solar radiation. Biophysical modelling for Far Eastern Victoria predicted that maximum temperatures <19.5 °C prevented V. varius activity and hence opportunity for bait removal. V. varius in WPNP was undetectable suggesting aerial baiting posed limited hazard to this species at this location. Depending how climate influences annual activity patterns and the specific poison, surface-laid baits could pose a significant mortality risk to V. varius. However, use of biophysical models to predict periods of V. varius inactivity may provide a novel means to reduce non-target bait take by this predator.     

Propagule pressure as a driver of establishment success in deliberately introduced exotic species: fact or artefact?

A central paradigm in invasion biology is that more releases of higher numbers of individuals increase the likelihood that an exotic population successfully establishes and persists. Recently, however, it has been suggested that, in cases where the data are sourced from historical records of purposefully released species, the direction of causality is reversed, and that initial success leads to higher numbers being released. Here, we explore the implications of this alternative hypothesis, and derive six a priori predictions from it. We test these predictions using data on Acclimatization Society introductions of passerine bird species to New Zealand, which have previously been used to support both hypotheses for the direction of causality. All our predictions are falsified. This study reaffirms that the conventional paradigm in invasion biology is indeed the correct one for New Zealand passerine bird introductions, for which numbers released determine establishment success. Our predictions are not restricted to this fauna, however, and we keenly anticipate their application to other suitable datasets.     

Cryptic introductions and the interpretation of island biodiversity

Species with cryptic origins (i.e. those that cannot be reliably classed as native or non‐native) present a particular challenge to our understanding of the generation and maintenance of biodiversity. Such species may be especially common on islands given that some islands have had a relatively recent history of human settlement. It is likely that select island species considered native might have achieved their current distributions via direct or indirect human actions. As an example, we explore the origins of eastern bluebirds (Sialia sialis bermudensis) on the island of Bermuda. Considered native to the island and a distinct subspecies, this population has diverged in morphology relative to mainland North America. Using microsatellite markers and simulation of island colonization, we show that the Bermuda population of bluebirds is the likely result of a single colonization event that occurred during the 1600s, making this a cryptic invader. To our knowledge, this is one of the youngest examples of a terrestrial vertebrate cryptic invader. We suggest that the eastern bluebird is not an isolated case of cryptic invader on either Bermuda or elsewhere and that caution be exercised when studying present‐day distributions of organisms.     

Synthesis and characterization of 123I-CMICE-013: A potential SPECT myocardial perfusion imaging agent

Coronary artery disease (CAD) is a major cause of death in Canada and the United States. Single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a useful diagnostic test in the management of patients with CAD. The widely used SPECT MPI agents, ^99mTc sestamibi and ^99mTc tetrofosmin, exhibit less than ideal pharmacokinetic properties with decreasing uptake with higher flows. ¹²³I has a similar energy as ^99mTc, an ideal half life, and is readily available from cyclotrons. The objective of this study was to develop an ¹²³I labeled MPI agent based on rotenone, a mitochondrial complex I inhibitor, as an alternative to currently available SPECT MPI agents. Methods: ¹²³I-CMICE-013 was synthesized by radiolabeling rotenone with ¹²³I in trifluoroacetic acid (TFA) with iodogen as the oxidizing agent at 60 °C for 45 min, followed by RP-HPLC purification. The product was formulated in 5% EtOH in 10 mM NaOAc pH 6.5. The inactive analog ¹²⁷I-CMICE-013 was isolated and characterized by NMR and mass spectrometry, and the structure determined. Micro-SPECT imaging studies were carried out in normal and infarcted rats. Biodistribution studies were performed in normal rats at 2 h (n = 6) and 24 h (n = 8) post injection (p.i.). Results: ¹²³I-CMICE-013 was isolated with >95% radiochemical purity and high specific activity (14.8–111 GBq/μmol; 400–3000 mCi/μmol). Structural analysis showed that rotenone was iodinated at 7′-position, with removal of the 6′,7′-double bond, and addition of a hydroxy group at 6′-position. MicroSPECT images in normal rats demonstrated homogeneous and sustained myocardial uptake with minimal interference from lung and liver. Absent myocardial perfusion was clearly identified in rats with permanent left coronary artery ligation and ischemia-reperfusion injury. In vivo biodistribution studies in normal rats at 2 h p.i. showed significant myocardial uptake (2.01 ± 0.48%ID/g) and high heart to liver (2.98 ± 0.93), heart to lung (4.11 ± 1.04) and heart to blood (8.37 ± 3.97) ratios. At 24 h p.i., the majority of ¹²³I-CMICE-013 was cleared from tissues, and a significant amount of tracer was found in the thyroid, indicating in vivo deiodination of the tracer. Conclusion: ¹²³I-CMICE-013 is a promising new radiotracer for SPECT MPI with high myocardial uptake, very good target to background ratios and favorable biodistribution characteristics.     

Somatoform disorders among patients attending walk-in clinics in Trinidad: prevalence and association with depression and anxiety

Objectives Somatoform disorders are common in international primary care settings, but have been little studied in the developing world. The objective of this study was to determine the prevalence of severe undifferentiated somatoform disorder, and its relationship to depression and anxiety, among patients attending walk-in clinics in Trinidad.Methods The study participants, who were all aged 18 years or older and attending walk-in clinics at 16 randomly selected health centres, were surveyed between May and August 2007 using the PRIME-MD questionnaire.Results There were 594 participants (the response rate was 92%), of whom 72.7% were female. Their ages ranged from 18 to 93 years, and 54.5% were over 50 years of age. In total, 37.2% were married and 25.9% were single. Indo-Trinidadians represented 43.1% and Afro-Trinidadians represented 36% of the study sample; 56.5% of the participants reported that their income was less than US$ 400 per month, and 65.7% were unemployed. At walk-in clinics in Trinidad, the estimated prevalence of severe undifferentiated somatoform disorder was 10.3% (95% CI: 7.86–12.74), that of hypochondriasis was 28.5% (95% CI: 24.9–32.1), and that of body dysmorphic disorder was 15.8% (95% CI: 11.9–18.7). Severe undifferentiated somatoform disorder was statistically significantly associated with gender and ethnicity but not with age, level of education, employment status or income. Chi-square testing found significant associations between the presence of severe undifferentiated somatoform disorder and both depression and anxiety (P < 0.05), between hypochondriasis and both anxiety and depression (P < 0.05), and between body dysmorphic disorder and depression (P < 0.05) but not anxiety. Regression analysis suggested that the demographic features that predicted severe undifferentiated somatoform disorder were being female or Indo-Trinidadian.Conclusions Walk-in clinics in Trinidad that serve older patients on a lower income have a high proportion of patients with somatoform disorders as measured by the PRIME-MD scale. These patients exhibit many features of anxiety and depression. These findings have implications for medical training and service delivery.     

Hydrophilic carotenoids: surface properties and aggregation of an astaxanthin-lysine conjugate, a rigid, long-chain, highly unsaturated and highly water-soluble tetracationic bolaamphiphile

The surface and aggregation properties of a synthetic, highly water-soluble carotenoid, the tetracationic astaxanthin-lysine conjugate (Asly), have been examined through measurements of surface tension, optical absorption and dynamic light scattering. The following parameters were determined: critical aggregation concentration c(M), surface concentration Gamma, molecular area a(m), free energy of adsorption and aggregation (DeltaG(ad) degrees and DeltaG(M) degrees , respectively), and the aggregate size r(H). The compound forms true monomolecular solutions in water below c(M); aggregates emerge only at rather high concentrations (> or =2.18 mM).     

Skin tight: cell adhesion in the epidermis of Caenorhabditis elegans

The powerful genetics, genomics and microscopy tools available for C. elegans make it well suited to studying how epithelial cells adhere to one another and the extracellular matrix, and how the integrated, simultaneous activities of multiple cell adhesion complexes function to shape an organism. Recent studies using forward and reverse genetics have shed light on how phylogenetically conserved cell adhesion complexes, such as the cadherin/catenin complex, claudins, the Discs large complex and hemidesmosome-like attachment structures, regulate epithelial cell adhesion, providing new insights into conserved cell adhesion mechanisms in higher eukaryotes.     

Angiogenic factors and the endometrium following long term progestin only contraception

Endometria from long term progestin only contraceptive-treated patients display abnormally enlarged blood vessels that are prone to bleeding as well as inflammation and possibly local diminution in blood flow. Such bleeding is also characterized by focal reductions in the expression of angiopoietin-1, a vessel stabilization and maturation agent, and excess production of the potent angiogenic agents, vascular endothelial growth factor and angiopoietin-2. In addition, tissue factor, the key initiator of hemostasis may play an angiogenic role either directly or via the activation of thrombin. This review article summarizes current findings related to the endometrial dysregulation of angiogenic/hemostatic agents following treatment with long term progestin only contraception. Studies in this area offer a promising avenue to alleviate abnormal uterine bleeding associated with this otherwise highly effective form of contraception     

Plasma appearance and tissue accumulation of non-esterified, free astaxanthin in C57BL/6 mice after oral dosing of a disodium disuccinate diester of astaxanthin (Heptax)

Oral bioavailability of natural and synthetic carotenoids is generally poor in rodents, and this has limited the ability to test these antioxidant compounds in well-defined rodent models of human disease. Various strategies have been employed, with variable success, to increase the percentage of the total oral dose absorbed by the rodent GI tract. In the current study, a novel carotenoid derivative (the disodium disuccinate diester of astaxanthin; Heptax) was administered by oral gavage in a lipophilic emulsion to C57BL/6 mice. Plasma appearance and tissue accumulation of non-esterified, free astaxanthin was studied by HPLC over 72 h after single- and multiple-dose regimens. One-time dosing of Heptax in emulsion at 500 mg/kg resulted in significant appearance of free astaxanthin in plasma (Cmax=0.2 mg/l; 381 nM) and accumulation in solid organs (e.g. liver Cmax=0.9 mg/l; 1735 nM), levels not previously reported after single carotenoid doses in rodents. At each point in the concentration/time curve (AUC), free astaxanthin levels in liver were greater than the corresponding concentration in plasma, suggesting concentrative uptake by the liver. As the ED50 as an antioxidant for non-esterified, free astaxanthin in model systems is approximately 200 nM, the current results suggest that hepatoprotection against oxidative insults may be achieved after a single dose of Heptax in these animals. In humans, where the bioavailability of oral carotenoids ranges from 40 to 60% of the total dose when given in lipophilic vehicle, much smaller oral doses may be utilized for therapeutic benefit in a particular clinical application.     

Promotion of peptide antimicrobial activity by fatty acid conjugation

Three peptides, YGAA[KKAAKAA](2) (AKK), KLFKRHLKWKII (SC4), and YG[AKAKAAKA](2) (KAK), were conjugated with lauric acid and tested for the effect on their structure, antibacterial activity, and eukaryotic cell toxicity. The conjugated AKK and SC4 peptides showed increased antimicrobial activity relative to unconjugated peptides, but the conjugated KAK peptide did not. The circular dichroism spectrum of AKK showed a significantly larger increase in its alpha-helical content in the conjugated form than peptide KAK in a solution containing phosphatidylethanolamine/phosphotidylglycerol vesicles, which mimics bacterial membranes. The KAK and AKK peptides and their corresponding fatty acid conjugates showed little change in their structure in the presence of phosphatidylcholine vesicles, which mimic the cell membrane of eukaryotic cells. The hemolytic activity of the KAK and AKK peptides and conjugates was low. However, the SC4 fatty acid conjugate showed a large increase in hemolytic activity and a corresponding increase in helical content in the presence of phosphatidylcholine vesicles. These results support the model of antimicrobial peptide hemolytic and antimicrobial activity being linked to changes in secondary structure as the peptides interact with lipid membranes. Fatty acid conjugation may improve the usefulness of peptides as antimicrobial agents by enhancing their ability to form secondary structures upon interacting with the bacterial membranes.