The Siblings With Ischemic Stroke Study (SWISS) Protocol

BACKGROUND: Family history and twins studies suggest an inherited component to ischemic stroke risk. Candidate gene association studies have been performed but have limited capacity to identify novel risk factor genes. The Siblings With Ischemic Stroke Study (SWISS) aims to conduct a genome-wide scan in sibling pairs concordant or discordant for ischemic stroke to identify novel genetic risk factors through linkage analysis. METHODS: Screening at multiple clinical centers identifies patients (probands) with radiographically confirmed ischemic stroke and a family history of at least 1 living full sibling with stroke. After giving informed consent, without violating privacy among other family members, the proband invites siblings concordant and discordant for stroke to participate. Siblings then contact the study coordinating center. The diagnosis of ischemic stroke in potentially concordant siblings is confirmed by systematic centralized review of medical records. The stroke-free status of potentially discordant siblings is confirmed by validated structured telephone interview. Blood samples for DNA analysis are taken from concordant sibling pairs and, if applicable, from 1 discordant sibling. Epstein-Barr virus-transformed lymphoblastoid cell lines are created, and a scan of the human genome is planned. DISCUSSION: Conducting adequately powered genomics studies of stroke in humans is challenging because of the heterogeneity of the stroke phenotype and the difficulty of obtaining DNA samples from clinically well-characterized members of a cohort of stroke pedigrees. The multicentered design of this study is intended to efficiently assemble a cohort of ischemic stroke pedigrees without invoking community consent or using cold-calling of pedigree members

Renin-angiotensin system inhibitors and risk of fractures: a prospective cohort study and meta-analysis of published observational cohort studies

The renin-angiotensin system (RAS) represents an important target of antihypertensive medications. Angiotensin-converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), which are widely-used RAS inhibiting drugs, have been suggested to have beneficial effects on bone tissue. We aimed to assess the associations of use of ACEIs and/or ARBs with the risk of fractures using a population-based prospective cohort and a meta-analysis of published prospective cohort studies. Information on antihypertensive medication use (including both ACEIs and ARBs) were assessed in 1743 men and women of the Kuopio Ischemic Heart Disease prospective cohort study. Hazard ratios (HRs) [95% confidence intervals (CI)] of ACEIs or ARBs use with incident fractures were calculated. A total of 203 composite (hip, humeral, and wrist) fractures occurred during a median follow-up of 14.8 years. In multivariate adjusted analysis, the HR for composite fractures comparing users of ACEIs or ARBs with non-users was 1.00 (0.59–1.69). The corresponding adjusted HR for hip fractures comparing users versus non-users of ACEIs or ARBs was 0.89 (0.32–2.47). Including the current study, a total of 11 observational cohort studies involving 3526,319 participants and &gt;323,355 fractures were included in a meta-analysis. Comparing ACEI users with non-users and ARB users with non-users, the HRs for composite fractures were 1.09 (0.89–1.33) and 0.87 (0.76–1.01) respectively. The corresponding HRs for hip fractures were 0.91 (0.86–0.95) and 0.80 (0.75–0.85) respectively. Use of RAS inhibitors was not associated with long-term risk of composite fractures in both primary and pooled analyses. Pooled evidence however suggests a beneficial effect of RAS blockers on hip fracture risk.</p

Wild mallards have more ‘‘goose-like’’ bills than their ancestors : a case of anthropogenic influence?

Wild populations of the world’s most common dabbling duck, the mallard (Anas platyrhynchos), run the risk of genetic introgression by farmed conspecifics released for hunting purposes. We tested whether bill morphology of free-living birds has changed since large-scale releases of farmed mallards started. Three groups of mallards from Sweden, Norway and Finland were compared: historical wild (before large-scale releases started), present-day wild, and present-day farmed. Higher density of bill lamellae was observed in historical wild mallards (only males). Farmed mallards had wider bills than present-day and historical wild ones. Present-day wild and farmed mallards also had higher and shorter bills than historical wild mallards. Present-day mallards thus tend to have more “goose-like” bills (wider, higher, and shorter) than their ancestors. Our study suggests that surviving released mallards affect morphological traits in wild population by introgression. We discuss how such anthropogenic impact may lead to a maladapted and genetically compromised wild mallard population. Our study system has bearing on other taxa where large-scale releases of conspecifics with ‘alien genes’ may cause a cryptic invasive process that nevertheless has fitness consequences for individual birds

Experimental quantification of long distance dispersal potential of aquatic snails in the gut of migratory birds

Many plant seeds and invertebrates can survive passage through the digestive system of birds, which may lead to long distance dispersal (endozoochory) in case of prolonged retention by moving vectors. Endozoochorous dispersal by waterbirds has nowadays been documented for many aquatic plant seeds, algae and dormant life stages of aquatic invertebrates. Anecdotal information indicates that endozoochory is also possible for fully functional, active aquatic organisms, a phenomenon that we here address experimentally using aquatic snails. We fed four species of aquatic snails to mallards (Anas platyrhynchos), and monitored snail retrieval and survival over time. One of the snail species tested was found to survive passage through the digestive tract of mallards as fully functional adults. Hydrobia (Peringia) ulvae survived up to five hours in the digestive tract. This suggests a maximum potential transport distance of up to 300 km may be possible if these snails are taken by flying birds, although the actual dispersal distance greatly depends on additional factors such as the behavior of the vectors. We put forward that more organisms that acquired traits for survival in stochastic environments such as wetlands, but not specifically adapted for endozoochory, may be sufficiently equipped to successfully pass a bird's digestive system. This may be explained by a digestive trade-off in birds, which maximize their net energy intake rate rather than digestive efficiency, since higher efficiency comes with the cost of prolonged retention times and hence reduces food intake. The resulting lower digestive efficiency allows species like aquatic snails, and potentially other fully functional organisms without obvious dispersal adaptations, to be transported internally. Adopting this view, endozoochorous dispersal may be more common than up to now thought.

Benefits of large broods by higher chick survival and better territories in a precocial shorebird

When reproductive success is constant in one breeding phase, different tactics that increase variation in reproductive success among individuals may evolve in other phases. For instance, in shorebirds, which usually have a limited clutch size of four eggs, variation in reproductive tactics among individuals is expected either before egg-laying (e.g. diverse mating systems) or after hatching of the young (e.g. diverse parental care). In this paper, I studied the pied avocet (Recurvirostra avosetta), a shorebird with a modal clutch size of four eggs, to test whether post-hatch chick adoption as an alternative tactic can be linked to increased variation in annual reproductive success. When predation was high, naturally adopting pairs produced more filial fledglings than did pairs not adopting chicks and not losing chicks to adoption. The number of filial fledglings increased with the number of adopted young, possibly through diluting the chances of predation on filial young. Experimental chick addition did not lead to more fledged young due to low brood integrity as shown by the frequent loss of chicks from some experimental broods. When predation was low, larger broods occupied feeding territories with higher prey abundance than smaller broods, possibly due to their dominance over smaller ones. Pairs that lost chicks to adoption (donors) fledged as many filial young in their broods as did non-adopters/non-donors, whereas the total number of donors' filial fledglings, including those raised in adopting broods, approached that of adopters. These findings show, for the first time, that post-hatch alternative reproductive tactics can lead to variation in annual reproductive success and to higher success for some pairs even in species where past adaptations limit variation in reproductive success in a certain phase of reproduction