The effect of MMP inhibitor GM6001 on early fibroblast-mediated collagen matrix contraction is correlated to a decrease in cell protrusive activity

Although fibroblasts play an essential part during the wound healing response, the mechanisms by which they mediate tissue remodelling and contraction are still unclear. Using live cell and matrix imaging within 3D free-floating fibroblast-populated collagen lattices as a model for tissue contraction, we compared the behaviour of a range of fibroblasts with low and high contraction abilities and analysed the effect of the broad spectrum MMP-inhibitor GM6001 on cell behaviour and matrix contraction. We identified two mechanisms underlying matrix contraction, one via direct cell-mediated contractile activity, the second through matrix degradation. These appear to be linked to cell morphology and regulated by the collagen concentration within the matrix. Cells with a rounded morphology proliferated in the matrix but did not remodel it efficiently, resulting in a poor ability to contract matrices. Cells with an elongated morphology showed higher levels of protrusive activity, leading to efficient matrix remodelling and contraction. GM6001 inhibited week-long matrix contraction to various extents with the different cell lines. However, quantitative analysis of the cell protrusive activity showed that GM6001 consistently decreased cell dynamics in 3D by about 20%, and this was correlated with a significant reduction in early matrix contraction. Overall our results suggest that although fibroblast-mediated matrix contraction depends on both cell dynamics and MMP-mediated matrix degradation, the efficiency of GM6001 treatment in preventing contraction might be linked to a direct effect on cell dynamics.     

Analysis of structural diversity in wolf-like canids reveals post-domestication variants

Background

Although a variety of genetic changes have been implicated in causing phenotypic differences among dogs, the role of copy number variants (CNVs) and their impact on phenotypic variation is still poorly understood. Further, very limited knowledge exists on structural variation in the gray wolf, the ancestor of the dog, or other closely related wild canids. Documenting CNVs variation in wild canids is essential to identify ancestral states and variation that may have appeared after domestication.

Results

In this work, we genotyped 1,611 dog CNVs in 23 wolf-like canids (4 purebred dogs, one dingo, 15 gray wolves, one red wolf, one coyote and one golden jackal) to identify CNVs that may have arisen after domestication. We have found an increase in GC-rich regions close to the breakpoints and around 1 kb away from them suggesting that some common motifs might be associated with the formation of CNVs. Among the CNV regions that showed the largest differentiation between dogs and wild canids we found 12 genes, nine of which are related to two known functions associated with dog domestication; growth (PDE4D, CRTC3 and NEB) and neurological function (PDE4D, EML5, ZNF500, SLC6A11, ELAVL2, RGS7 and CTSB).

Conclusions

Our results provide insight into the evolution of structural variation in canines, where recombination is not regulated by PRDM9 due to the inactivation of this gene. We also identified genes within the most differentiated CNV regions between dogs and wolves, which could reflect selection during the domestication process.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-465) contains supplementary material, which is available to authorized users.     

Cognitive State following Stroke: The Predominant Role of Preexisting White Matter Lesions

Background and purpose

Stroke is a major cause of cognitive impairment and dementia in adults, however the role of the ischemic lesions themselves, on top of other risk factors known in the elderly, remains controversial. This study used structural equation modeling to determine the respective impact of the new ischemic lesions'' volume, preexisting white matter lesions and white matter integrity on post stroke cognitive state.

Methods

Consecutive first ever mild to moderate stroke or transient ischemic attack patients recruited into the ongoing prospective TABASCO study underwent magnetic resonance imaging scans within seven days of stroke onset and were cognitively assessed one year after the event using a computerized neuropsychological battery. The volumes of both ischemic lesions and preexisting white matter lesions and the integrity of the normal appearing white matter tissue were measured and their contribution to cognitive state was assessed using structural equation modeling path analysis taking into account demographic parameters. Two models were hypothesized, differing by the role of ischemic lesions'' volume.

Results

Structural equation modeling analysis of 142 patients confirmed the predominant role of white matter lesion volume (standardized path coefficient β = −0.231) and normal appearing white matter integrity (β = −0.176) on the global cognitive score, while ischemic lesions'' volume showed no such effect (β = 0.038). The model excluding the ischemic lesion presented better fit to the data (comparative fit index 0.9 versus 0.092).

Conclusions

Mild to moderate stroke patients with preexisting white matter lesions are more vulnerable to cognitive impairment regardless of their new ischemic lesions. Thus, these patients can serve as a target group for studies on cognitive rehabilitation and neuro-protective therapies which may, in turn, slow their cognitive deterioration.     

Patterns of Spatial and Temporal Distribution of Humpback Whales at the Southern Limit of the Southeast Pacific Breeding Area

Understanding the patterns of spatial and temporal distribution in threshold habitats of highly migratory and endangered species is important for understanding their habitat requirements and recovery trends. Herein, we present new data about the distribution of humpback whales (Megaptera novaeangliae) in neritic waters off the northern coast of Peru: an area that constitutes a transitional path from cold, upwelling waters to warm equatorial waters where the breeding habitat is located. Data was collected during four consecutive austral winter/spring seasons from 2010 to 2013, using whale-watching boats as platforms for research. A total of 1048 whales distributed between 487 groups were sighted. The spatial distribution of humpbacks resembled the characteristic segregation of whale groups according to their size/age class and social context in breeding habitats; mother and calf pairs were present in very shallow waters close to the coast, while dyads, trios or more whales were widely distributed from shallow to moderate depths over the continental shelf break. Sea surface temperatures (range: 18.2–25.9°C) in coastal waters were slightly colder than those closer to the oceanic realm, likely due to the influence of cold upwelled waters from the Humboldt Current system. Our results provide new evidence of the southward extension of the breeding region of humpback whales in the Southeast Pacific. Integrating this information with the knowledge from the rest of the breeding region and foraging grounds would enhance our current understanding of population dynamics and recovery trends of this species.     

Elimination of Sarcoptes scabiei in Pig Herds by Single or Double Administrations of an Avermectin

Attempts to eliminate Sarcoptes scabiei var. suis were made in 2 piglet producing herds by intramuscular injections with doramectin (Dectomax™, Pfizer inc., New York, USA). No hygienic measures of the environments were undertaken. In herd A, all animals were treated twice at a 14-day interval. Theoretically it should be possible to eliminate the mite with a single injection and therefore the animals in herd B were treated only once. The results were measured by attempts to demonstrate S. scabiei by skin scrapings, by recording skin lesions, by establishing rubbing indexes, and by measuring serum antibodies to S. scabiei. All adult animals greater than 8 months of age and 15 weaned piglets 8–16 weeks of age per herd were investigated prior to treatments and every fourth month for a total of 20 months following administration of the treatments. Live S. scabiei were demonstrated prior to treatments in both herds, but no further. Skin lesion scores, rubbing indexes and serum antibody levels remained low throughout the study. It is possible to eliminate S. scabiei from a herd with one single injection of doramectin. Precautions must be taken to ensure that all animals get a correct dose and that the drug is properly administered.