To trigger or not to trigger ovulation in a natural cycle for frozen embryo transfer: a randomized controlled trial.

STUDY QUESTION: Is the clinical pregnancy rate (CPR) following a frozen embryo transfer (FET) in a natural cycle (NC) higher after spontaneous ovulation than after triggered ovulation [natural cycle frozen embryo transfer (NC-FET) versus modified NC-FET]? SUMMARY ANSWER: The CPR did not vary significantly between the two FET preparation protocols. WHAT IS KNOWN ALREADY: Although the use of FET is continuously increasing, the most optimal endometrial preparation protocol is still under debate. For transfer in the NC specifically, conflicting results have been reported in terms of the outcome following spontaneous or triggered ovulation. STUDY DESIGN, SIZE, DURATION: In a tertiary hospital setting, subjects were randomized with a 1:1 allocation into two groups between January 2014 and January 2019. Patients in group A underwent an NC-FET, while in group B, a modified NC-FET was performed with a subcutaneous hCG injection to trigger ovulation. In neither group was additional luteal phase support administered. All embryos were vitrified-warmed on Day 3 and transferred on Day 4 of embryonic development. The primary outcome was CPR at 7 weeks. All patients were followed further until 10 weeks of gestation when the ongoing pregnancy rate (OPR) was defined by the observation of foetal cardiac activity on ultrasound scan. Other secondary outcomes included biochemical pregnancy rate, early pregnancy loss and the number of visits, blood samples and ultrasonographic examinations prior to FET. PARTICIPANTS/MATERIALS, SETTING, METHODS: A total of 260 patients (130 per study arm) were randomized, of whom 12 withdrew consent after study arm allocation. A total of 3 women conceived spontaneously before initiating the study cycle and 16 did not start for personal or medical reasons. Of the 229 actually commencing monitoring for the study FET cycle, 7 patients needed to be switched to a hormonal replacement treatment protocol due to the absence of follicular development, 12 had no embryo available for transfer after warming and 37 had a spontaneous LH surge before the ovulation trigger could be administered, although they were allocated to group B. Given the above, an intention-to-treat (ITT) analysis was performed taking into account 248 patients (125 in group A and 123 in group B), as well as a per protocol (PP) analysis on a subset of 173 patients (110 in group A and 63 in group B). MAIN RESULTS AND THE ROLE OF CHANCE: Demographic features were evenly distributed between the study groups, as were the relevant fresh and frozen ET cycle characteristics. According to the ITT analysis, the CPR and OPR in group A (33.6% and 27.2%, respectively) and group B (29.3% and 24.4%, respectively) did not vary significantly [relative risk (RR) 0.87, 95% CI (0.60;1.26), P = 0.46 and RR 0.90, 95% CI (0.59;1.37), P = 0.61, respectively]. Biochemical pregnancy rate and early pregnancy loss were also found to be not statistically significantly different between the groups. In contrast, more clinic visits and blood samplings for cycle monitoring were required in the NC-FET group (4.05 ± 1.39) compared with the modified NC-FET group (3.03 ± 1.16, P = <0.001), while the number of ultrasound scans performed were comparable (1.70 ± 0.88 in group A versus 1.62 ± 1.04 in group B). The additional PP analysis was in line with the ITT results: CPR in group A was 36.4% versus 38.1% in group B [RR 1.05, 95% CI (0.70;1.56), P = 0.82]. LIMITATIONS, REASONS FOR CAUTION: The results are limited by the high drop-out rate for the PP analysis in the modified NC-FET group as more than one-third of the subjects allocated to this group ovulated spontaneously before ovulation triggering. Nonetheless, this issue is inherent to routine clinical practice and is an important observation of an event that can only be avoided by performing a very extensive monitoring that limits the practical advantages associated with modified NC-FET. Furthermore, although this is the largest randomized controlled trial (RCT) investigating this specific research question so far, a higher sample size would allow smaller differences in clinical outcome to be detected, since currently they may be left undetected. WIDER IMPLICATIONS OF THE FINDINGS: This RCT adds new high-quality evidence to the existing controversial literature concerning the performance of NC-FET versus modified NC-FET. Based on our results showing no statistically significant differences in clinical outcomes between the protocols, the treatment choice may be made according to the patient's and treating physician's preferences. However, the modified NC-FET strategy reduces the need for hormonal monitoring and may therefore be considered a more patient-friendly and potentially cost-effective approach. STUDY FUNDING/COMPETING INTEREST(S): No specific funding was available for this study. None of the authors have a conflict of interest to declare with regard to this study. TRIAL REGISTRATION NUMBER: NCT02145819. TRIAL REGISTRATION DATE: 8 January 2014. DATE OF FIRST PATIENT'S ENROLMENT: 21 January 2014.

Seroprevalence and risk factors of Toxoplasma gondii infection in invasive raccoons (Procyon lotor) in Central Europe.

Toxoplasma gondii is an obligate intracellular protozoan that causes toxoplasmosis in warm-blooded animals. Most mammals, including humans, can become intermediate host, resulting in subclinical infection or even death. Generally, there is limited information on the epidemiology of T. gondii of game species in Germany. As omnivores, raccoons, which are particularly widespread and abundant in Germany, are particularly exposed to infection the parasite. Here, we report the seroprevalence of T. gondii antibodies from 15 study sites located in Luxembourg and Germany. Using the indirect modified agglutination test (MAT), 170 (37.4%; 95% CI: 33.0-41.9) out of 454 raccoons were surveyed to be T. gondii seropositive. While values ranged from 19.0% to 53.3%, there was no significant difference in seroprevalence between study areas. Animal weight had a strong influence on the presence of T. gondii antibodies in raccoon sera, with heavier animals more likely to be seropositive. Our results show that T. gondii infection is widespread in central European raccoons, suggesting a high degree of ecosystem circulation of the parasite.

Revisiting the phylogeography and demography of European badgers (Meles meles) based on broad sampling, multiple markers and simulations.

Although the phylogeography of European mammals has been extensively investigated since the 1990s, many studies were limited in terms of sampling distribution, the number of molecular markers used and the analytical techniques employed, frequently leading to incomplete postglacial recolonisation scenarios. The broad-scale genetic structure of the European badger (Meles meles) is of interest as it may result from historic restriction to glacial refugia and/or recent anthropogenic impact. However, previous studies were based mostly on samples from western Europe, making it difficult to draw robust conclusions about the location of refugia, patterns of postglacial expansion and recent demography. In the present study, continent-wide sampling and analyses with multiple markers provided evidence for two glacial refugia (Iberia and southeast Europe) that contributed to the genetic variation observed in badgers in Europe today. Approximate Bayesian computation provided support for a colonisation of Scandinavia from both Iberian and southeastern refugia. In the whole of Europe, we observed a decline in genetic diversity with increasing latitude, suggesting that the reduced diversity in the peripheral populations resulted from a postglacial expansion processes. Although MSVAR v.1.3 also provided evidence for recent genetic bottlenecks in some of these peripheral populations, the simulations performed to estimate the method's power to correctly infer the past demography of our empirical populations suggested that the timing and severity of bottlenecks could not be established with certainty. We urge caution against trying to relate demographic declines inferred using MSVAR with particular historic or climatological events.

Dendritic organization of neurons of the superior colliculus in animals with different visual capability.

The aim of the study was to compare several morphological characteristics of neurons in the superficial layers of the superior colliculus in diurnal and nocturnal mammals with different visual specialization. Thus, we investigated the rat (Rattus norvegicus), a nocturnal animal; the tree shrew (Tupaia glis), a diurnal animal, and the Mongolian rodents, Microtus brandti (nocturnal) and Alticola barakshin (diurnal). The investigation was focused on the study of the organization and extent of dendrites of Golgi-impregnated projection neurons, which were divided in two classes: narrow-field and wide-field cells. We determined that the ratios between the volumes of dendritic fields of the investigated neuronal types and the total volume of the superior colliculus differed to a great extent between the different species. The tree shrew had the largest superior colliculus and the smallest wide-field neurons, while the rat had the largest wide-field neurons. As for the Mongolian rodents, we provided the first description of superior colliculus neurons. The day-active animal Alticola barakshin was found to have a 50% larger volume of the superior colliculus than that of the night-active animal Microtus brandti, and the size of the dendritic field of both wide-field neurons and narrow-field neurons was smaller than that of Microtus brandti. Electron microscopic investigation of wide-field neurons performed in the rat revealed only a few symmetric synaptic contacts on the arborizations of distal and terminal dendrites and numerous asymmetric synapses on the dendritic stem. Our findings support the hypothesis that whereas the narrow-field neurons are relay neurons in the retino-tecto-thalamic pathway of the visual system, the wide-field neurons may play additional roles in the retino-tecto-reticulo-spinal system.

[Neurons in the visual cortex of Microtus brandti]. / Neuronen im visuellen Cortex von Microtus brandti.

Neurons were described in the visual Cortex of Microtus brandti, a Mongolian harmful rodent living in day-activity. We find following types of neurons in our Golgi-material: 1. spiny neurons: pyramidal and stellate neurons. 2. smooth or sparsely spined neurons: smooth, large neurons, sparsely spined small neurons with descending axons, sparsely spined neurons with ascending axons. Double-bouquet-, chandelier and neuroglioforme cells are not impregnated. There are no bipolare neurons (Martinotti cells) among the neurons with ascending axons. The small, sparsely spined neurons are not only in lamina IV - like in other species - but they can also be found in laminae II to IV. Their distribution of spines on the distal parts of dendrites seems to be characteristical for rodents. The lamination of the visual cortex of Microtus brandti is the same like in the rat. All cells are of large size in relation to the body mass of the animal.

[Volumetric and golgi studies of the corpus geniculatum laterale pars dorsalis of Alticola stoliczkanus barakshin and Alticola argentatus semicanus]. / Volumetrische und Golgi-Studien am Corpus geniculatum laterale pars doralis Alticola Stoliczkanus barakshin und Alticola argentatus semicanus.

The dorsal lateral geniculate bodies (dLGB) in Alticola stoliczkanus barakshin, the Gobi-Altai-Mountain vole, and in Alticola argentatus semicanus, the silver grey mountain vole, and investigated using the nissl- and the golgi method. The geniculo-cortico-relay neurons (GCR neurons) of both species have 5 primary dendrites (D1), a dendritic field of about 100 micron, about 17 free dendritic distal parts (FDE), 10 branching points (VZP) and a average of the perikaryon of 10 micron. All tufted neurons are small and topographically distinctly localised. The dLGB's volume of Alticola stoczkanus, barakshin is 0.16 mm3, the dLGB's volume of Alticola argentatus semicanus is 0.23 mm3.

Karyotypes and systematics of Asian high-mountain voles, genus Alticola (Rodentia, Arvicolidae). Results of Mongolian-German biological expeditions since 1962, No. 211.

Six species/subspecies of Asian high-mountain voles, genus Alticola, were studied cytogenetically via conventional staining and C- and G-banding. The karyotypes are very similar. The standard karyotype, as in A. strelzovi strelzovi, consists of 56 chromosomes. These are split into 25 acrocentric pairs, one large subtelocentric pair, one small metacentric pair, a large acrocentric X chromosome, and a small Y chromosome, which varies in shape. Constitutive heterochromatin is almost entirely restricted to small centromeric regions. A small submetacentric pair of autosomes in both subspecies of A. semicanus and a medium-sized Y chromosome in A. argentatus severtzovi are of importance in systematics. The data suggest that A. barakshin, A. semicanus, and A. argentatus are separate species.