Pleiotropic effects of statins: do they matter?

Treatment with the 3-hydroxy-3-methylglutaryl coenyzme A reductase inhibitors (or statins) reduces the risk for cardiovascular events across a broad spectrum of patient profiles, as evidenced by both primary prevention and secondary prevention trials. Improved survival by way of reduced deaths from coronary heart disease was also reported with these agents, which are primarily indicated for substantial reduction in LDL-cholesterol levels. However, the statins are extremely complex drugs and exhibit a wide variety of vascular effects that may or may not be dependent on their lipid-modifying properties. These so-called pleiotropic effects include alterations of endothelial function, inflammation, coagulation, and plaque stability. The relative contribution of the nonlipid effects of statin therapy to the well-documented clinical benefits is currently under intense investigation.     

Spillover effects of retirement: Does health vulnerability matter?

The current literature investigating the impact of retirement and the associated spousal spillover effects overlooks the unintended effects of retirement on spouses in vulnerable health, namely spouses with long-term health conditions (LTHCs). In this paper, we fill this gap in the literature and investigate the impact of an individual’s retirement on their partner’s health outcomes when their partner has LTHCs. Given the inherent identification challenges associated with entry into retirement, we use the pension-qualifying age in Australia as an instrument. Based on data from the Household Income and Labour Dynamics in Australia survey, we find that the husband’s retirement has a positive impact on the wife’s quality-adjusted life years (QALY) and other physical and mental health outcomes. We also identify redistribution of domestic workload as a key transmission mechanism of the spousal spillover effects. Women with LTHCs will see their QALY and health improve only if their husband devotes more time to domestic tasks after retirement.     

Testing the importance of nest concealment: does timing matter?

ABSTRACT.   Nest concealment by vegetation is considered an important factor affecting predation rates for many passerines and, therefore, is frequently measured in studies examining nest predation. However, the time when concealment measurements are made may affect the results of such studies, particularly in highly seasonal ecosystems where characteristics of the vegetation later in the breeding period may differ considerably from those at the time of nest-site selection. We used artificial nests baited with quail ( Coturnix sp.) eggs in a highly seasonal tropical dry forest in Jalisco, western Mexico, to test the effects of seasonal change in concealment on nest predation. We placed 40 open-cup, artificial nests in shrubs at the end of the dry season and again at the beginning of the rainy season in 2007, and monitored the fate of the nests and the degree of concealment by vegetation during both periods. Nest concealment was significantly greater during the wet season than during the dry season. The percentage of nests predated was marginally higher during the dry (100%) than the wet (72.5%) season, and daily nest survival was lower during the dry than the wet season. Our results suggest that, in highly seasonal environments such as tropical dry forests, delayed measurement of nest concealment after nest completion rather than during nesting may constitute a significant source of error.     

Invasion success: does size really matter?

The recent paper by Roy et al . (2001) presents a compelling relationship between range limit shifts, climatic fluctuations, and body size for marine bivalves in the fossil record. However, their extension of body size as a correlate for contemporary marine bivalve introductions is problematic and requires further scrutiny. Unlike their analysis of the fossil assemblage, the approach used for contemporary invasions does not adequately control for dispersal mechanism (vector) or source region. First, their analysis included mariculture species, intentionally introduced because of their large size, creating a vector-specific bias. Second, successful invaders from multiple source regions (Northern Hemisphere) were compared with potential invaders from a single source region (north-eastern Pacific), leaving both source and vector as uncontrolled variables. We present an analysis of body size for bivalve introductions from a single vector and source region, indicating no correlation between body size and invasion success when eliminating intentional introduction, source region and transport vector as confounding factors.     

Pathogen recognition and development of particulate vaccines: does size matter?

The use of particulate carriers holds great promise for the development of effective and affordable recombinant vaccines. Rational development requires a detailed understanding of particle up-take and processing mechanisms to target cellular pathways capable of stimulating the required immune responses safely. These mechanisms are in turn based on how the host has evolved to recognize and process pathogens. Pathogens, as well as particulate vaccines, come in a wide range of sizes and biochemical compositions. Some of these also provide 'danger signals' so that antigen 'senting cells (APC), usually dendritic cells (DC), acquire specific stimulatory activity. Herein, we provide an overview of the types of particles currently under investigation for the formulation of vaccines, discuss cellular uptake mechanisms (endocytosis, macropinocytosis, phagocytosis, clathrin-dependent and/or caveloae-mediated) for pathogens and particles of different sizes, as well as antigen possessing and presentation by APC in general, and DC in particular. Since particle size and composition can influence the immune response, inducing humoral and/or cellular immunity, activating CD8 T cells and/or CD4 T cells of T helper 1 and/or T helper 2 type, particle characteristics have a major impact on vaccine efficacy. Recently developed methods for the formulation of particulate vaccines are presented in this issue of Methods, showcasing a range of "cutting edge" particulate vaccines that employ particles ranging from nano to micro-sized. This special issue of Methods further addresses practical issues of production, affordability, reproducibility and stability of formulation, and also includes a discussion of the economic and regulatory challenges encountered in developing vaccines for veterinary use and for common Third World infectious diseases.     

Pacemakers in aggregation fields of Dictyostelium discoideum: does a single cell suffice?

In this paper we address the following question: can a single cell of the cellular slime mold Dictyostelium discoideum serve as a pacemaker for the aggregation phase? Whether or not this is possible is determined by the relative importance of cyclic AMP production due to self-stimulation as compared to diffusion of cyclic AMP away from the cell and extracellular degradation. We determine the conditions under which a single cell on an infinite place can emit periodic signals of cyclic AMP using a model developed previously for signal relay and adaptation in Dictyostelium. Elsewhere it has been shown that this model provides an accurate representation of the stimulus-response behavior of Dictyostelium for a variety of experimental conditions.     

Subjective symptoms among mobile phone users—A consequence of absorption of radiofrequency fields?

In a previous epidemiological study, where we studied the prevalence of subjective symptoms among mobile phone (MP) users, we found as an interesting side finding that the prevalence of many of the subjective symptoms increased with increasing calling time and number of calls per day. In this extrapolative study, we have selected 2402 people from the epidemiological study who used any of the four most common GSM MP. We used the information about the prevalence of symptoms, calling time per day, and number of calls per day and combined it with measurements of the Specific Absorption Rate (SAR). We defined three volumes in the head and measured the maximum SAR averaged over a cube of 1 g tissue (SAR(1g)) in each volume. Two new exposure parameters Specific Absorption per Day (SAD) and Specific Absorption per Call (SAC) have been devised and are obtained as combinations of SAR, calling time per day, and number of calls per day, respectively. The results indicates that SAR values >0.5 W/kg may be an important factor for the prevalence of some of the symptoms, especially in combination with long calling times per day.     

Guilds or functional groups: does it matter?

Although most researchers use the terms "guild" and "functional group" more or less synonymously, these two concepts bear different meanings. The guild concept refers primarily to the mechanisms of resource sharing by species in a competitive context whereas the functional groups concept is concerned with how a resource or any other ecological component is processed by different species to provide a specific ecosystem service or function. In many cases but not necessarily all, the two concepts are the two "faces" or "sides" of the same coin: the sharing by species of a similar resource is the guild facet (structural), while the ecosystem processes these species eventually perform through resource exploitation is the functional group facet. The two concepts differ in that competitive relationships within groups of species are not the focus of the functional group approach, exactly as processes or functions are not the focus of the guild approach. A group of species can be considered either as a guild or a functional group depending on the question addressed. Guild and functional group membership is independent of phylogenetic relationships but because species tend to share similar life history traits and adaptations through common evolutionary history, guild and functional group associates are often closely related. The concept of guild has had broader application in animal studies than in plant studies, whereas the reverse is true for the concept of functional group. Recent methodological advances to objectively partition species into guilds and functional groups, taking into consideration the most relevant characters or traits for delineating them, provide the means to construct an operational framework for making in situ and ex situ experiments that are urgently needed for a better understanding of the role of species in ecosystem functioning, especially in relation to global change concerns.     

Magellanic Penguin eggshell pores: does number matter?

Most penguin species lay two eggs 3–4 days apart that hatch 1–2 days apart. Hypotheses to explain the shorter incubation period for the second egg include differences in porosity of the eggshells. Eggs with more or larger pores and/or thinner shells have higher gas exchange rates and faster embryonic development. We used eggshells from hatchling Magellanic Penguins Spheniscus magellanicus to test whether eggshell thickness and pore density affect incubation period. We expected: (i) second eggs to have thinner shells and/or more pores than first eggs; (ii) eggs to have thinner shells and/or more pores if they were laid by older females, later in the season, or in burrow nests (more humid than open nests under bushes). We found no support for these hypotheses. Egg pores and shell thickness were not related to incubation period. Eggs from the same clutch were similar in eggshell thickness and pore density. Female age, laying date and nest type were poor predictors of eggshell thickness and pore density. Egg pores, we conclude, have little explanatory power for differences in incubation time of eggs in Magellanic Penguins, and suggest that synchronous onset of incubation matters.     

Benign prostatic hyperplasia: does prostate size matter?

Recent studies and analyses have confirmed that baseline prostate volume is related to progression of benign prostatic hyperplasia (BPH) as well as to negative outcomes related to BPH, such as acute urinary retention (AUR) and need for surgery, and can also predict response to therapy. Other investigations have determined that prostate-specific antigen (PSA) level has good predictive value for assessing prostate volume. Strong evidence exists that baseline serum PSA level, like baseline prostate volume, predicts future prostate growth. Randomized placebo-controlled finasteride trials have shown that men with larger prostate volumes and higher PSA levels experience a clinically significant response to therapy compared with those with smaller prostate volumes and lower PSA levels. It has also been demonstrated that men with larger prostate glands and higher PSA levels are at increased risk for AUR and BPH-related surgery but that finasteride reduces these risks. Moreover, doxazosin and finasteride, alone and in combination, have been shown to significantly reduce BPH clinical progression.     

Measuring diversity of endophytic fungi in leaf fragments: does size matter?

Endophytic fungi inhabit living plant tissues without causing disease symptoms. Although abundant, the extent of their contribution to fungal biodiversity remains unclear. Since endophytic fungi are poorly known, especially in the tropics, current estimates of fungal species are probably conservative. Here we tested strategies for sampling endophytic fungi in tropical plants. We compared the number of fungi isolated from 400 mm2 leaf pieces that were divided into increasingly small fragments. Leaf pieces were surface-sterilized, cut into fragments and plated on culture media. For a given area, cutting leaf pieces into smaller fragments significantly increased the number of fungal morphospecies recovered. There was a strong linear relationship between size of fragments and number of fungi isolated. By extrapolation, an estimated 16 +/- 3 fungi could be recovered from a 2 x 2 cm leaf piece, using infinitely small fragments. This represents a large part of the fungal diversity estimated to exist in leaf endophytes in a population. We conclude that reducing the size and increasing the number of leaf fragments will increase the number of fungal species isolated. This strategy will help to estimate real values of endophytic fungal diversity.     

Patterns of endemism in African birds: how much does taxonomy matter?

It has been suggested that the 'right' biogeographic patterns will only arise with a species concept reflecting the finest splitting of terminal phylogenetic branches. The significance of taxonomic resolution was assessed using distributional data for all resident African land-birds, held at the Zoological Museum of Copenhagen. The primary database (in a one-degree geographical grid) served as a template for creating two new databases: one, where the distributional records were allocated to species according to the 'Speciation Atlases' for African birds (Hall and Moreau 1970, Snow 1978) and two, according to the finest taxonomic splitting that has since then been suggested in the literature. With this spatial resolution, the species richness pattern is almost exactly the same whether old or new taxonomy is used. The endemism follows another pattern with marked local aggregates. The location of principal aggregates are quite robust to recent splitting, although a slightly more complex structure appears. Also some small new areas of endemism emerge, each with 2–3 narrow endemics. However, large portions of African savannah and lowland rainforest are still characterised by a total lack of narrow endemism. Based on the current understanding of diversification processes and adaptive re-distribution it is suggested that the uneven distribution of narrowly endemic and widespread species will persist even if it were possible, in the future, to define terminal taxa in a consistent way.