Evolution towards Multi-Year Periodicity in Epidemics

We studied why many diseases has multi-year period in their epidemiological dynamics, whereas a main source of the fluctuation is a seasonality with period of one year. Previous studies using a compartment model succeeded to generate a multi-year epidemics when they have a large seasonal difference in a transmission rate. However, those studies have focused on the dynamical consequence of seasonal forcing in epidemiological dynamics and an adaptation of pathogens in the seasonal environment has been neglected. In this paper, we describe our study of the evolution of pathogens sensitivity to seasonality and show that a larger fluctuation in the transmission rate can be favored in the life history evolution of pathogens, suggesting that multi-year periodicity may evolve by natural selection. Our result Our result proposes a new aspect of the evolution of multi-year epidemics

The Role of Trade-off Shapes in the Evolution and Coexistence of Virulence in Spatial Host-Parasite Interactions: An Approximate Adaptive Dynamical Approach

We propose a new analysis for the evolution of virulence of pathogen in a spatially structured host population where each site of a regular lattice is either occupied by a susceptible or by an infected, or is empty. We assume that reproduction by susceptible individuals occurs locally but infection by a contact of susceptible and infected hosts occurs either locally or globally with a certain proportion. We examine by combining Monte-Carlo simulation and adaptive dynamics approach, how the evolutionarily stable (ESS) virulence depends on the fraction of global infection/transmission and the trade-off between transmission and virulence in the model investigated by Boots and Sasaki (1999). Our analysis developed in this paper can successfully predicted the ESS virulence found in the previous papers, and reveals followings: [1] With a linear trade-off, as is reported by previous studies, there is an ESS virulence when the proportion of global infection is small. We newly find that, if we increase the proportion, the ESS disappears when the proportion exceeds a certain threshold value, and proportions just below the threshold, there are evolutionary bi-stabilities. [2] With a non-linear trade-off, there can be no monomorphic ESS; instead, the evolutionary competition between many parasite genotypes differing in their virulence gives rise to an evolutionarily stable coalition of pathogen strains with markedly different virulence (dimorphic ESS virulence) with a middle proportion of global transmission. These analytical results well illustrate the results by Monte-Carlo simulations. Since coexistence and evolutionary bistability are not impossible in the model we investigate in this paper, these are apparently derived by the effect of spatial structure

The Role of Trade-off Shapes in the Evolution of Parasites in Spatial Host Populations: An Approximate Analytical Approach

Given the substantial changes in mixing in many populations, there is considerable interest in the role that spatial structure can play in the evolution of disease. Here we examine the role of different trade-off shapes in the evolution of parasites in a spatially structured host population where infection can occur locally or globally. We develop an approximate adaptive dynamic analytical approach, to examine how the evolutionarily stable (ES) virulence depends not only on the fraction of global infection/transmission but also on the shape of the trade-off between transmission and virulence. Our analysis can successfully predict the ES virulence found previously by simulation of the full system. The analysis confirms that when there is a linear trade-off between transmission and virulence spatial structure may lead to an ES virulence that increases as the proportion of global transmission increases. However, we also show that the ESS disappears above a threshold level of global infection, leading to maximization. In addition just below this threshold, there is the possibility of evolutionary bi-stabilities. When we assume the realistic trade-off between transmission and virulence that results in an ESS in the classical mixed model, we find that spatial structure can increase or decrease the ES virulence. A relatively high proportion of local infection reduces virulence but intermediate levels can select for higher virulence. Our work not only emphasizes the importance of spatial structure to the evolution of parasites, but also makes it clear that situations between the local and the global need to be considered. We also emphasize the key role that the shape of trade-offs plays in evolutionary outcomes

Anti-inflammatory sesquiterpenes from Curcuma zedoaria

This is a preprint of an article whose final and definitive form has been published in the NATURAL PRODUCT RESEARCH © 2006 copyright Taylor & Francis; NATURAL PRODUCT RESEARCH is available online at: http://www.informaworld.com/openurl?genre=article&issn=1478-6419&volume=20&issue=7&spage=680ArticleNATURAL PRODUCT RESEARCH. 20(7): 680-685 (2006)journal articl

Japanese version of the family dermatology life quality index: translation and validation

Skin conditions affect the quality of life (QoL) of patients and their family. To assess family members' QoL, a questionnaire uniquely designed for family members is necessary. We translated the Family Dermatology Life Quality Index (FDLQI), originally created and validated by Basra et al., into Japanese, and evaluated its reliability and validity. For psychometric evaluations, 150 dermatology patients and their family members were included. The Japanese version of the FDLQI showed high test–retest reliability (intraclass correlation coefficient = 0.95) and internal consistency reliability (Cronbach's alpha = 0.86). FDLQI scores significantly correlated with DLQI scores (r = 0.58, P < 0.01, Spearman's rho) and global question (GQ) which measured the patient's skin condition on a visual analog scale (r = 0.36, P < 0.01). Family members of patients with inflammatory skin diseases showed higher FDLQI scores than those with isolated lesions, but the difference was not statistically significant (P = 0.062, Mann–Whitney U-test). Responsiveness to change was demonstrated in a group in which the patient's skin condition was assessed as improved (n = 37, r = 0.46, P < 0.01) but not in that in which it became worse. The difference of the change between the two groups was statistically significant (P < 0.01). Additionally, the change in FDLQI scores and GQ were significantly correlated (r = 0.40, P < 0.01). Exploratory factor analysis suggested essential unidimensionality of the instrument. We showed acceptable validity and responsiveness of this Japanese version of FDLQI. Further clinical epidemiological studies are required to confirm this

Cyanamide mode of action during inhibition of onion (Allium cepa L.) root growth involves disturbances in cell division and cytoskeleton formation

Cyanamide is an allelochemical produced by hairy vetch (Vicia villosa Roth.). Its phyotoxic effect on plant growth was examined on roots of onion (Allium cepa L.) bulbs. Water solution of cyanamide (2–10 mM) restricted growth of onion roots in a dose-dependent manner. Treatment of onion roots with cyanamide resulted in a decrease in root growth rate accompanied by a decrease in accumulation of fresh and dry weight. The inhibitory effect of cyanamide was reversed by its removal from the environment, but full recovery was observed only for tissue treated with this chemical at low concentration (2–6 mM). Cytological observations of root tip cells suggest that disturbances in cell division may explain the strong cyanamide allelopathic activity. Moreover, in cyanamide-treated onion the following changes were detected: reduction of mitotic cells, inhibition of proliferation of meristematic cells and cell cycle, and modifications of cytoskeleton arrangement