Objective Residual anastomoses after fetoscopic laser surgery for twin-to-twin transfusion syndrome (TTTS) may lead to severe postoperative complications, including recurrent TTTS and twin ...anemia-polycythemia sequence (TAPS). A novel technique (Solomon technique) using laser coagulation of the entire vascular equator was recently investigated in a randomized controlled trial (Solomon trial) and compared with the Standard selective laser technique. The aim of this secondary analysis was to evaluate the occurrence and characteristics of residual anastomoses in placentas included in the Solomon trial. Study Design International multicenter randomized controlled trial in TTTS, randomized 1:1 ratio to either the Solomon laser technique or Standard laser technique. At time of laser, surgeons recorded whether they considered the procedure to be complete. Placental dye injection was performed after birth in the participating centers to evaluate the presence of residual anastomoses. Results A total of 151 placentas were included in the study. The percentage of placentas with residual anastomoses in the Solomon group and Standard group was 19% (14/74) and 34% (26/77), respectively ( P = .04). The percentage of placentas with residual anastomoses in the subgroup of cases where the procedure was recorded as complete was 8/65 (12%) and 22/69 (32%) in the Solomon group and Standard group, respectively ( P < .01). Conclusion The Solomon laser technique reduces the risk of residual anastomoses. However, careful follow-up remains essential also after the Solomon technique, as complete dichorionization is not always achieved.
Many studies propose that Quaternary climatic cycles contracted and/or expanded the ranges of species and biomes. Strong expansion–contraction dynamics of biomes presume concerted demographic changes ...of associated fauna. The analysis of temporal concordance of demographic changes can be used to test the influence of Quaternary climate on diversification processes. Hierarchical approximate Bayesian computation (hABC) is a powerful and flexible approach that models genetic data from multiple species, and can be used to estimate the temporal concordance of demographic processes. Using available single‐locus data, we can now perform large‐scale analyses, both in terms of number of species and geographic scope. Here, we first compared the power of four alternative hABC models for a collection of single‐locus data. We found that the model incorporating an a priori hypothesis about the timing of simultaneous demographic change had the best performance. Second, we applied the hABC models to a data set of seven squamate and four amphibian species occurring in the Seasonally Dry Tropical Forests (Caatinga) in northeastern Brazil, which, according to paleoclimatic evidence, experienced an increase in aridity during the Pleistocene. If this increase was important for the diversification of associated xeric‐adapted species, simultaneous population expansions should be evident at the community level. We found a strong signal of synchronous population expansion in the Late Pleistocene, supporting the increase of the Caatinga during this time. This expansion likely enhanced the formation of communities adapted to high aridity and seasonality and caused regional extirpation of taxa adapted to wet forest.
Abstract To evaluate the relative risk of placental abruption in monochorionic (MC) twin pregnancies complicated with twin-to-twin transfusion syndrome (TTTS) and treated with endoscopic laser ...coagulation of placental vessels (ELCPV). A retrospective analysis from January 2004 and December 2015 of 373 TTTS pregnancies, treated with selective ELCPV until January 2012 (287 cases), after which the Solomon technique was introduced (86 cases), compared with 243 normal MC pregnancies. A significant improvement in perinatal survival was observed after the introduction of the Solomon technique when compared to the selective procedure (77% vs 54%, p < 0.001). The rate of placental abruption was 1% (3/243) in normal MC pregnancies, 6% (21/373) in TTTS group, increased with Solomon technique (12/86, 14%, vs 9/287, 3%, p < 0.001). MC twin pregnancies treated with laser coagulation of placental vascular anastomoses could be at increased risk of placental abruption, especially when the Solomon technique is used.
Active flight requires the ability to efficiently fuel bursts of costly locomotion while maximizing energy conservation during non-flying times. We took a multi-faceted approach to estimate how ...fruit-eating bats (
) manage a high-energy lifestyle fueled primarily by fig juice. Miniaturized heart rate telemetry shows that they use a novel, cyclic, bradycardic state that reduces daily energetic expenditure by 10% and counteracts heart rates as high as 900 bpm during flight.
support flight with some of the fastest metabolic incorporation rates and dynamic circulating cortisol in vertebrates. These bats will exchange fat reserves within 24 hr, meaning that they must survive on the food of the day and are at daily risk of starvation. Energetic flexibly in
highlights the fundamental role of ecological pressures on integrative energetic networks and the still poorly understood energetic strategies of animals in the tropics.
Context
Rivers, landscape, and climate can alter patterns of gene flow and consequently, shape intraspecific genetic variation. While rivers are predicted to halt gene flow in terrestrial species, ...they may facilitate migration for aquatic species. Amphibians are usually seen as water-dependent, yet multiple studies have indicated that rivers exert a barrier effect on these organisms.
Objectives
In this study, we investigated the effects of rivers and other abiotic factors, such as climate and geography on genetic variation of a highly aquatic frog (
Pseudis tocantins
) inhabiting central Brazil.
Methods
We sequenced fragments of one mitochondrial and two nuclear genes of 179 individuals of
P. tocantins
from 19 localities along the Tocantins-Araguaia Basin in Brazil and used Generalized Dissimilarity Modeling (GDM) to test the role of rivers, landscape, and climate features on its genetic differentiation. Next, we tested three scenarios of migration along the Tocantins-Araguaia Basin using approximate Bayesian computation (ABC).
Results
We found that genetic differentiation among localities is mostly explained by the influence of river connectivity. Conversely, elevation, slope, and past and current climate have little or no impact on genetic differentiation. Furthermore, our results show that patterns of migration took place directionally, from upstream to downstream sites.
Conclusions
Rivers have shaped patterns of intraspecific diversity in
P. tocantins
by acting as the most important facilitator of gene flow. Therefore, we suggest that future research should include the role of rivers as a facilitator of gene flow, especially for those species that are associated with aquatic environments.
•Flying squirrels have high cortisol, but a carrier protein with low cort affinity.•Negative feedback regulation was thus tested, showing a reduced sensitivity to DEX.•Stress axis function was tested ...seasonally showing cort regulation at a high set point.•Cort and the capacity to respond to acute stress were higher in non-breeding animals.•Females had higher cort and binding protein, and DEX sensitivity varied seasonally.
Southern flying squirrels have higher circulating cortisol levels than most vertebrates. However, regulation of tissue exposure to cortisol by the hormone’s carrier protein, corticosteroid-binding globulin (CBG), appears to be altered due to lower-than-expected CBG expression levels, and a reduced affinity for cortisol. To assess the capacity of flying squirrels to regulate acute stress-mediated cortisol levels, we used the dexamethasone (DEX) suppression test followed by the adrenocorticotropic hormone (ACTH) stimulation test in both the breeding and non-breeding seasons, and quantified resultant changes in plasma cortisol and relative CBG levels. Regulation of cortisol via negative feedback, and the acute stress response appeared to function as they do in other vertebrates during the breeding season, but response to DEX in the non-breeding season showed that the sensitivity of the negative feedback mechanism changed across seasons. The relatively high concentrations of DEX required to induce negative feedback suggests that southern flying squirrels have a reduced sensitivity to cortisol compared with other vertebrates, and that high circulating cortisol levels may be required to compensate for low target tissue responsiveness in this species. Cortisol, but not CBG levels, were higher during the non-breeding than breeding season, and females had higher cortisol and CBG levels than males. Our data suggest that flying squirrel cortisol levels are regulated by negative feedback at a higher set point than in related species. Seasonal changes in cortisol levels, target tissue sensitivity to DEX, and in the capacity to respond to stressors appear to be part of the underlying physiology of southern flying squirrels, and may be required to maximize fitness in the face of tradeoffs between survival and reproduction.
PDF
