Landscape Genetics Reveals Focal Transmission of a Human Macroparasite

Macroparasite infections (e.g., helminths) remain a major human health concern. However, assessing transmission dynamics is problematic because the direct observation of macroparasite dispersal among hosts is not possible. We used a novel landscape genetics approach to examine transmission of the human roundworm Ascaris lumbricoides in a small human population in Jiri, Nepal. Unexpectedly, we found significant genetic structuring of parasites, indicating the presence of multiple transmission foci within a small sampling area (∼14 km²). We analyzed several epidemiological variables, and found that transmission is spatially autocorrelated around households and that transmission foci are stable over time despite extensive human movement. These results would not have been obtainable via a traditional epidemiological study based on worm counts alone. Our data refute the assumption that a single host population corresponds to a single parasite transmission unit, an assumption implicit in many classic models of macroparasite transmission. Newer models have shown that the metapopulation-like pattern observed in our data can adversely affect targeted control strategies aimed at community-wide impacts. Furthermore, the observed metapopulation structure and local mating patterns generate an excess of homozygotes that can accelerate the spread of recessive traits such as drug resistance. Our study illustrates how molecular analyses complement traditional epidemiological information in providing a better understanding of parasite transmission. Similar landscape genetic approaches in other macroparasite systems will be warranted if an accurate depiction of the transmission process is to be used to inform effective control strategies.     

Atomistic uniaxial tension tests: investigating various many-body potentials for their ability to produce accurate stress strain curves using molecular dynamics simulations

Molecular dynamics simulations, which take place on the atomistic scale, are now being used to predict the influence of atomistic processes on macro-scale mechanical properties. However, there is a lack of clear understanding on which potential should be used when attempting to obtain these properties. Moreover, many MD studies that do test mechanical properties do not actually simulate the macro-scale laboratory tension tests used to obtain them. As such, the purpose of the current study was to evaluate the various types of potentials for their accuracy in predicting the mechanical properties of iron from an atomistic uniaxial tension test at room temperature. Results demonstrated that while EAM and MEAM potentials all under predicted the elastic modulus at room temperature, the Tersoff and ReaxFF potentials were significantly more accurate. Unlike EAM and MEAM, both the Tersoff and ReaxFF potentials are bond order based. Therefore, these results demonstrate the importance of considering bonding between atoms when modelling tensile tests. In addition, the ReaxFF potential also accurately predicted the Poisson's ratio, allowing for complete characterisation of the material's behaviour. Overall, these findings highlight the need to understand the capabilities and limitations of each potential before application to a problem outside of the initial intended use.     

Chemical Components from Phaeanthus vietnamensis and Their Inhibitory NO Production in BV2 Cells

Phaeanthus vietnamensis Bân is a well‐known medicinal plant which has been used for the treatment of various inflammatory diseases in traditional medicine. Using various chromatographic methods, three new compounds, (7S,8R,8′R)‐9,9′‐epoxy‐3,5,3′,5′‐tetramethoxylignan‐4,4′,7‐triol ( 1 ), 8α‐hydroxyoplop‐11(12)‐en‐14‐one ( 5 ), and (1R,2S,4S)‐4‐acetyl‐2‐[(E)‐(cinnamoyloxy)]‐1‐methylcyclohexan‐1‐ol ( 12 ) along with twelve known compounds were isolated from the leaves of P. vietnamensis. Their chemical structures were elucidated by physical and chemical methods. All compounds were evaluated for the inhibitory activities of nitric oxide production in LPS‐stimulated BV2 cells. As the results, compound 6 showed the most potent inhibitory activity on LPS‐stimulated NO production in BV2 cells with the IC₅₀ values of 15.7 ± 1.2 μm . Compounds 2 , 7 , and 8 significantly inhibited inflammatory NO production with IC₅₀ values ranging from 22.6 to 25.3 μm .     

Ketopiperazine-based renin inhibitors: optimization of the "C" ring

A systematic investigation of the S3 sub-pocket activity requirements was conducted. It was observed that linear and sterically small side chain substituents are preferred in the S3 sub-pocket for optimal renin inhibition. Polar groups in the S3-sub-pocket were not well tolerated and caused a reduction in renin inhibitory activity. Further, compounds with clog P's < or = 3 demonstrated a dramatic reduction in CYP3A4 inhibitory activity.     

Invasive plants – Do they devastate or diversify rural livelihoods? Rural farmers’ perception of three invasive plants in Nepal

In this paper, we examine how rural people in the buffer zone of Chitwan National Park in Nepal perceive the effects of accidently transported invasive plant species, such as Mikania micrantha, Lantana camara and Chromolaena odorata, on their livelihoods. We found that their perception of the impact of each species on their livelihood varies with factors such as the duration of the presence of invasive plants in the landscape, and household characteristics. Results of a household survey indicate that farm households close to the forests have responded to the invasive species both as a victim and a beneficiary. Farm households are likely to adapt to the invaded environment as they have a history of interacting with invasive plants and can commoditise them through appropriate intervention. Additionally, the findings indicate that rural people are willing to invest in the control and management of invasive plants if appropriate technical assistance is available. Without assistance, they consider mitigating the infestation an unattainable mission and consider acceptance of the invasive species as a part of the rural ecosystem an inevitable outcome.     

Sensitivity and specificity of body mass index as a definition of the obesity component of metabolic syndrome

Metabolic syndrome (MS) is a combination of risk factors that are associated with several chronic diseases. Its components (obesity, dyslipidemia, carbohydrate intolerance, hypertension, microalbumineria) are diverse, whose thresholds vary in different definitions of MS. For example, a World Health Organization (WHO) panel defined the obesity component of MS based on waist-hip ratio, or body mass index (BMI), while the National Cholesterol Education Program (NCEP) defined the obesity component of MS by waist circumference. Since BMI is the common measure of obesity in most epidemiological studies, this research addressed how accurately the obesity component of MS is captured by BMI alone. Data presented showed that in a population with high prevalence of obesity, the specificity of detecting the obesity component of MS by BMI alone is almost 100%, but the sensitivity is low (e.g., < 50%). Individuals with high BMI generally have large waist-hip ratio and wide waist circumference, but the converse is not necessarily true. Consequently, centralized obesity (a risk factor for several chronic diseases) is not always captured by a high BMI alone.