Rapid changes in the gut microbiome during human evolution

Humans are ecosystems containing trillions of microorganisms, but the evolutionary history of this microbiome is obscured by a lack of knowledge about microbiomes of African apes. We sequenced the gut communities of hundreds of chimpanzees, bonobos, and gorillas and developed a phylogenetic approach to reconstruct how present-day human microbiomes have diverged from those of ancestral populations. Compositional change in the microbiome was slow and clock-like during African ape diversification, but human microbiomes have deviated from the ancestral state at an accelerated rate. Relative to the microbiomes of wild apes, human microbiomes have lost ancestral microbial diversity while becoming specialized for animal-based diets. Individual wild apes cultivate more phyla, classes, orders, families, genera, and species of bacteria than do individual humans across a range of societies. These results indicate that humanity has experienced a depletion of the gut flora since diverging from Pan.The human microbiome is shaped by host genetics, environment, and lifestyle (1–3); thus, humanity''s unique evolutionary and cultural histories must have altered our associations with microorganisms (4). Despite intensive investigation of the microbiomes of humans spanning a range of geographic locations and cultures (5–7), how the composition of the microbiome has changed since humans diverged from other species, and since human populations diverged from one another, remains unclear, owing to a lack of knowledge about the microbiomes of ancestral hominid populations.Understanding how the composition of the human microbiome has changed over evolutionary time requires the inclusion of the microbiomes of phylogenetic outgroups (i.e., the African apes) into analyses of human microbiomes. Previous comparisons of the gut microbiomes of humans and the African apes have been restricted to just a few individuals per host species (8), precluding detection of the precise compositional differences that distinguish the microbiomes of the host species. Comparing the microbiomes of populations of chimpanzees, bonobos, gorillas, and humans while considering the phylogenetic relatedness among the hosts can reveal how the composition of the microbiome has changed since the host species diversified.Here we used a phylogenetic approach to identify the shifts in the composition of the microbiome that occurred along the lineages leading to the extant species of Homo and Pan. This analysis shows that humans across a range of cultures and geographies harbor microbiomes that are disproportionately divergent from those within wild apes. In particular, among the living hominid species, humans harbor uncharacteristically low levels of microbial diversity within their gut microbiomes.     

Validation of a neurofeedback paradigm: Manipulating frontal EEG alpha-activity and its impact on mood

It is claimed that neurofeedback (NF) is an effective treatment for a variety of psychiatric disorders. NF, within an operant conditioning framework, helps individuals to regulate cortical electroencephalographic (EEG) activity while receiving feedback from a visual or acoustic signal. For example, changing asymmetry between left and right frontal brain alpha activity by NF, is claimed to be an efficacious treatment for major depressive disorder. However, the specificity of this intervention in occasioning electrophysiological changes at target locations and target wave-frequencies, and its relation to changes in mood, has not been established. During a single session of NF, it was tested if the balance between left and right frontal alpha-activity could be changed, regardless of direction, in 40 healthy females. Furthermore, we investigated whether this intervention was electrophysiologically specific and if it was associated with changes in mood. Participants were able to decrease or increase frontal alpha-asymmetry during the intervention. However, no changes in mood were observed. Changes in EEG activity were specific in terms of location and wave-frequency.     

Dynamics of Antibodies to Ebolaviruses in an Eidolon helvum Bat Colony in Cameroon

The ecology of ebolaviruses is still poorly understood and the role of bats in outbreaks needs to be further clarified. Straw-colored fruit bats (Eidolon helvum) are the most common fruit bats in Africa and antibodies to ebolaviruses have been documented in this species. Between December 2018 and November 2019, samples were collected at approximately monthly intervals in roosting and feeding sites from 820 bats from an Eidolon helvum colony. Dried blood spots (DBS) were tested for antibodies to Zaire, Sudan, and Bundibugyo ebolaviruses. The proportion of samples reactive with GP antigens increased significantly with age from 0–9/220 (0–4.1%) in juveniles to 26–158/225 (11.6–70.2%) in immature adults and 10–225/372 (2.7–60.5%) in adult bats. Antibody responses were lower in lactating females. Viral RNA was not detected in 456 swab samples collected from 152 juvenile and 214 immature adult bats. Overall, our study shows that antibody levels increase in young bats suggesting that seroconversion to Ebola or related viruses occurs in older juvenile and immature adult bats. Multiple year monitoring would be needed to confirm this trend. Knowledge of the periods of the year with the highest risk of Ebolavirus circulation can guide the implementation of strategies to mitigate spill-over events.     

Extended,virtual and augmented reality in thoracic surgery: a systematic review

 Open in a separate windowOBJECTIVESExtended reality (XR), encompassing both virtual reality (VR) and augmented reality, allows the user to interact with a computer-generated environment based on reality. In essence, the immersive nature of VR and augmented reality technology has been warmly welcomed in all aspects of medicine, gradually becoming increasingly feasible to incorporate into everyday practice. In recent years, XR has become increasingly adopted in thoracic surgery, although the extent of its applications is unclear. Here, we aim to review the current applications of XR in thoracic surgery.METHODSA systematic database search was conducted of original articles that explored the use of VR and/or augmented reality in thoracic surgery in EMBASE, MEDLINE, Cochrane database and Google Scholar, from inception to December 2020.RESULTSOur search yielded 1494 citations, of which 21 studies published from 2007 to 2019 were included in this review. Three main areas were identified: (i) the application of XR in thoracic surgery training; (ii) preoperative planning of thoracic procedures; and (iii) intraoperative assistance. Overall, XR could produce progression along the learning curve, enabling trainees to reach acceptable standards before performing in the operating theatre. Preoperatively, through the generation of 3D-renderings of the thoracic cavity and lung anatomy, VR increases procedural accuracy and surgical confidence through familiarization of the patient’s anatomy. XR-assisted surgery may have therapeutic use particularly for complex cases, where conventional methods would yield inadequate outcomes due to inferior accuracy.CONCLUSIONXR represents a salient step towards improving thoracic surgical training, as well as enhancing preoperative planning and intraoperative guidance.