Synthetic approaches to polycyclic semiochemicals and their derivatives: combinatorial methods towards phytochemicals

Semiochemicals are natural products occurring in plants, bacteria or animals which function as carriers of a special message. Depending on the mode of function of the semiochemicals, they are divided into pheromones that trigger a response in members of the same species and allelochemicals (kairomones, allomones) that act between individuals of different species. Semiochemicals are very important compounds that influence the behavior of plants and animals and their adaption to a changing environment. As their importance for plants, animals and the ecological system itself is huge, the synthetic access to these chemicals, their precursors and derivatives is of high interest. Beyond novel strategies for the construction of semiochemical skeletons, combinatorial methods have been implemented to synthesize medium-sized and large-sized libraries that enable diverse modifications of the active compounds. These combinatorial approaches allow the screening for more active compounds and they elucidate the mode of action of the semiochemical or of the biological target. This review summarizes the state of the art procedures for the synthesis of important skeletons appearing in semiochemicals and gives special synthetic procedures for selected examples if the procedure is suitable for a general transfer to the synthesis of derivatives. The synthetic examples are given in the context of known active phytochemicals and their function that allows an evaluation of the given procedures with respect to the fulfillment of the common structural requirements (the structural diversity and flexibility) and the importance for the regulation of biological systems. Parts of this review were given in a lecture at the BioCom 12 in Cadiz, 2012.     

Fertilizer application decreases insect abundance on Plantago lanceolata: a large-scale experiment in three geographic regions

Humans have substantially altered the nitrogen cycle of ecosystems through the application of agricultural fertilizer. Fertilization may not only affect plant species diversity, but also insect dynamics by altering plant nitrogen supplies. We investigated the effect of experimental fertilization on the vegetation, with the ribwort plantain as the focal plant, and on higher trophic levels on differently managed grasslands throughout Germany. Over a period of 2 years, we examined two specialist herbivores and their parasitoid on Plantago lanceolata L., and the composition and structure of the surrounding vegetation. Over 70 sites in three geographic regions, within the large-scale project “German Biodiversity Exploratories”, were included in the study. The model system consisted of the host plant P. lanceolata L., the monophagous weevils Mecinus labilis Herbst and M. pascuorum Gyllenhal, and their parasitoid Mesopolobus incultus Walker. Fertilization decreased plant species richness and host plant abundance, whereas it enhanced the total vegetation growth. The increased size and heigher leaf nitrogen content did not improve herbivore performance. On the contrary, the abundance of the two herbivores was decreased by fertilization. The parasitoid depended on the abundance of one of its hosts, M. pascuorum (positively density-dependent). Reduced herbivore abundance due to fertilization might be explained by a lower abundance of the host plant, a lower stalk number, and by changed patterns of host localization within higher vegetation. Fertilization negatively affected the third trophic level by cascading up via host abundance. The relationships between fertilization, surrounding vegetation and the tritrophic system were measured throughout the three regions and over the 2-year period. Our findings present consequences of intensification for a plant–herbivore–parasitoid system, and may have significant implications for the conservation of multitrophic systems in managed grasslands.     

Retention in Care of HIV-Infected Children from HIV Test to Start of Antiretroviral Therapy: Systematic Review

Background

In adults it is well documented that there are substantial losses to the programme between HIV testing and start of antiretroviral therapy (ART). The magnitude and reasons for loss to follow-up and death between HIV diagnosis and start of ART in children are not well defined.

Methods

We searched the PubMed and EMBASE databases for studies on children followed between HIV diagnosis and start of ART in low-income settings. We examined the proportion of children with a CD4 cell count/percentage after after being diagnosed with HIV infection, the number of treatment-eligible children starting ART and predictors of loss to programme. Data were extracted in duplicate.

Results

Eight studies from sub-Saharan Africa and two studies from Asia with a total of 10,741 children were included. Median age ranged from 2.2 to 6.5 years. Between 78.0 and 97.0% of HIV-infected children subsequently had a CD4 cell count/percentage measured, 63.2 to 90.7% of children with an eligibility assessment met the eligibility criteria for the particular setting and time and 39.5 to 99.4% of the eligible children started ART. Three studies reported an association between low CD4 count/percentage and ART initiation while no association was reported for gender. Only two studies reported on pre-ART mortality and found rates of 13 and 6 per 100 person-years.

Conclusion

Most children who presented for HIV care met eligibility criteria for ART. There is an urgent need for strategies to improve the access to and retention to care of HIV-infected children in resource-limited settings.     

Poxvirus Antigen Staining of Immune Cells as a Biomarker to Predict Disease Outcome in Monkeypox and Cowpox Virus Infection in Non-Human Primates

Infection of non-human primates (NHPs) such as rhesus and cynomolgus macaques with monkeypox virus (MPXV) or cowpox virus (CPXV) serve as models to study poxvirus pathogenesis and to evaluate vaccines and anti-orthopox therapeutics. Intravenous inoculation of macaques with high dose of MPXV (>1–2×10⁷ PFU) or CPXV (>10² PFU) results in 80% to 100% mortality and 66 to 100% mortality respectively. Here we report that NHPs with positive detection of poxvirus antigens in immune cells by flow cytometric staining, especially in monocytes and granulocytes succumbed to virus infection and that early positive pox staining is a strong predictor for lethality. Samples from four independent studies were analyzed. Eighteen NHPs from three different experiments were inoculated with two different MPXV strains at lethal doses. Ten NHPs displayed positive pox-staining and all 10 NHPs reached moribund endpoint. In contrast, none of the three NHPs that survived anticipated lethal virus dose showed apparent virus staining in the monocytes and granulocytes. In addition, three NHPs that were challenged with a lethal dose of MPXV and received cidofovir treatment were pox-antigen negative and all three NHPs survived. Furthermore, data from a CPXV study also demonstrated that 6/9 NHPs were pox-antigen staining positive and all 6 NHPs reached euthanasia endpoint, while the three survivors were pox-antigen staining negative. Thus, we conclude that monitoring pox-antigen staining in immune cells can be used as a biomarker to predict the prognosis of virus infection. Future studies should focus on the mechanisms and implications of the pox-infection of immune cells and the correlation between pox-antigen detection in immune cells and disease progression in human poxviral infection.     

Internet-Delivered Cognitive Behavioural Therapy for Adults with Mild to Moderate Depression and High Cardiovascular Disease Risks: A Randomised Attention-Controlled Trial

Background and Aim

Mild to moderate depression is common in those with cardiovascular disease and undertreated. We aimed to evaluate the effectiveness of internet-delivered Cognitive Behaviour Therapy (iCBT) on depressive symptom severity and adherence to medical advice and lifestyle interventions in adults with mild to moderate depression and high cardiovascular disease (CVD) risks.

Methods

Randomised double-blind, 12 week attention-controlled trial comparing an iCBT programme (E-couch) with an internet-delivered attention control health information package (HealthWatch, n = 282). The primary outcome was depression symptom level on the nine-item Patient Health Questionnaire (PHQ-9) (trial registration: ACTRN12610000085077).

Results

487/562 (88%) participants completed the endpoint assessment. 383/562 (70%) were currently treated for cardiovascular disease and 314/562 (56%) had at least one other comorbid condition. In ITT analysis of 562 participants iCBT produced a greater decline in the mean PHQ-9 score compared to the attention control of 1.06 (95% CI: 0.23–1.89) points, with differences between the two arms increasing over the intervention period (time by treatment effect interaction p = .012). There were also larger improvements in adherence (2.16 points; 95% CI: 0.33–3.99), reductions in anxiety (0.96 points; 95% CI: 0.19–1.73), and a greater proportion engaging in beneficial physical activity (Odds Ratio 1.91, 95%CI: 1.01–3.61) in the iCBT participants but no effect upon disability, or walking time/day. There were no withdrawals due to study related adverse events.

Conclusions

In people with mild to moderate depression and high levels of CVD risk factors, a freely accessible iCBT programme (http://www.ecouch.anu.edu.au) produced a small, but robust, improvement in depressive symptoms, adherence and some health behaviours.

Trial Registration

Australian and New Zealand Clinical Trials Registry ACTRN12610000085077     

Improving Metabolic Health in Obese Male Mice via Diet and Exercise Restores Embryo Development and Fetal Growth

Paternal obesity is now clearly associated with or causal of impaired embryo and fetal development and reduced pregnancy rates in humans and rodents. This appears to be a result of reduced blastocyst potential. Whether these adverse embryo and fetal outcomes can be ameliorated by interventions to reduce paternal obesity has not been established. Here, male mice fed a high fat diet (HFD) to induce obesity were used, to determine if early embryo and fetal development is improved by interventions of diet (CD) and/or exercise to reduce adiposity and improve metabolism. Exercise and to a lesser extent CD in obese males improved embryo development rates, with increased cell to cell contacts in the compacting embryo measured by E-cadherin in exercise interventions and subsequently, increased blastocyst trophectoderm (TE), inner cell mass (ICM) and epiblast cell numbers. Implantation rates and fetal development from resulting blastocysts were also improved by exercise in obese males. Additionally, all interventions to obese males increased fetal weight, with CD alone and exercise alone, also increasing fetal crown-rump length. Measures of embryo and fetal development correlated with paternal measures of glycaemia, insulin action and serum lipids regardless of paternal adiposity or intervention, suggesting a link between paternal metabolic health and subsequent embryo and fetal development. This is the first study to show that improvements to metabolic health of obese males through diet and exercise can improve embryo and fetal development, suggesting such interventions are likely to improve offspring health.     

Phenotypic Switching Induced by Damaged Matrix Is Associated with DNA Methyltransferase 3A (DNMT3A) Activity and Nuclear Localization in Smooth Muscle Cells (SMC)

Extracellular matrix changes are often crucial inciting events for fibroproliferative disease. Epigenetic changes, specifically DNA methylation, are critical factors underlying differentiated phenotypes. We examined the dependency of matrix-induced fibroproliferation and SMC phenotype on DNA methyltransferases. The cooperativity of matrix with growth factors, cell density and hypoxia was also examined. Primary rat visceral SMC of early passage (0–2) were plated on native collagen or damaged/heat-denatured collagen. Hypoxia was induced with 3% O₂ (balanced 5% CO₂ and 95% N₂) over 48 hours. Inhibitors were applied 2–3 hours after cells were plated on matrix, or immediately before hypoxia. Cells were fixed and stained for DNMT3A and smooth muscle actin (SMA) or smooth muscle myosin heavy chain. Illumina 450 K array of CpG sites was performed on bisulfite-converted DNA from smooth muscle cells on damaged matrix vs native collagen. Matrix exquisitely regulates DNMT3A localization and expression, and influences differentiation in SMCs exposed to denatured matrix +/− hypoxia. Analysis of DNA methylation signatures showed that Matrix caused significant DNA methylation alterations in a discrete number of CpG sites proximal to genes related to SMC differentiation. Matrix has a profound effect on the regulation of SMC phenotype, which is associated with altered expression, localization of DNMTs and discrete changes DNA methylation.     

The Bacillus cereus Hbl and Nhe Tripartite Enterotoxin Components Assemble Sequentially on the Surface of Target Cells and Are Not Interchangeable

Bacillus cereus is a spore-forming, Gram-positive bacterium commonly associated with outbreaks of food poisoning. It is also known as an opportunistic pathogen causing clinical infections such as bacteremia, meningitis, pneumonia, and gas gangrene-like cutaneous infections, mostly in immunocompromised patients. B. cereus secretes a plethora of toxins of which four are associated with the symptoms of food poisoning. Two of these, the non-hemolytic enterotoxin Nhe and the hemolysin BL (Hbl) toxin, are predicted to be structurally similar and are unique in that they require the combined action of three toxin proteins to induce cell lysis. Despite their dominant role in disease, the molecular mechanism of their toxic function is still poorly understood. We report here that B. cereus strain ATCC 10876 harbors not only genes encoding Nhe, but also two copies of the hbl genes. We identified Hbl as the major secreted toxin responsible for inducing rapid cell lysis both in cultured cells and in an intraperitoneal mouse toxicity model. Antibody neutralization and deletion of Hbl-encoding genes resulted in significant reductions of cytotoxic activity. Microscopy studies with Chinese Hamster Ovary cells furthermore showed that pore formation by both Hbl and Nhe occurs through a stepwise, sequential binding of toxin components to the cell surface and to each other. This begins with binding of Hbl-B or NheC to the eukaryotic membrane, and is followed by the recruitment of Hbl-L₁ or NheB, respectively, followed by the corresponding third protein. Lastly, toxin component complementation studies indicate that although Hbl and Nhe can be expressed simultaneously and are predicted to be structurally similar, they are incompatible and cannot complement each other.     

Prevalence and Phylogenetic Analysis of Hepatitis B in Captive and Wild-Living Pileated Gibbons (Hylobates pileatus) in Cambodia

International Journal of Primatology - The risk of transmitting novel pathogens from released animals to wild conspecifics is an important consideration for reintroduction initiatives. Apart from...