What is the Oxygen Isotope Composition of Venus? The Scientific Case for Sample Return from Earth’s “Sister” Planet

Venus is Earth’s closest planetary neighbour and both bodies are of similar size and mass. As a consequence, Venus is often described as Earth’s sister planet. But the two worlds have followed very different evolutionary paths, with Earth having benign surface conditions, whereas Venus has a surface temperature of 464 °C and a surface pressure of 92 bar. These inhospitable surface conditions may partially explain why there has been such a dearth of space missions to Venus in recent years.The oxygen isotope composition of Venus is currently unknown. However, this single measurement (Δ17O) would have first order implications for our understanding of how large terrestrial planets are built. Recent isotopic studies indicate that the Solar System is bimodal in composition, divided into a carbonaceous chondrite (CC) group and a non-carbonaceous (NC) group. The CC group probably originated in the outer Solar System and the NC group in the inner Solar System. Venus comprises 41% by mass of the inner Solar System compared to 50% for Earth and only 5% for Mars. Models for building large terrestrial planets, such as Earth and Venus, would be significantly improved by a determination of the Δ17O composition of a returned sample from Venus. This measurement would help constrain the extent of early inner Solar System isotopic homogenisation and help to identify whether the feeding zones of the terrestrial planets were narrow or wide.Determining the Δ17O composition of Venus would also have significant implications for our understanding of how the Moon formed. Recent lunar formation models invoke a high energy impact between the proto-Earth and an inner Solar System-derived impactor body, Theia. The close isotopic similarity between the Earth and Moon is explained by these models as being a consequence of high-temperature, post-impact mixing. However, if Earth and Venus proved to be isotopic clones with respect to Δ17O, this would favour the classic, lower energy, giant impact scenario.We review the surface geology of Venus with the aim of identifying potential terrains that could be targeted by a robotic sample return mission. While the potentially ancient tessera terrains would be of great scientific interest, the need to minimise the influence of venusian weathering favours the sampling of young basaltic plains. In terms of a nominal sample mass, 10 g would be sufficient to undertake a full range of geochemical, isotopic and dating studies. However, it is important that additional material is collected as a legacy sample. As a consequence, a returned sample mass of at least 100 g should be recovered.Two scenarios for robotic sample return missions from Venus are presented, based on previous mission proposals. The most cost effective approach involves a “Grab and Go” strategy, either using a lander and separate orbiter, or possibly just a stand-alone lander. Sample return could also be achieved as part of a more ambitious, extended mission to study the venusian atmosphere. In both scenarios it is critical to obtain a surface atmospheric sample to define the extent of atmosphere-lithosphere oxygen isotopic disequilibrium. Surface sampling would be carried out by multiple techniques (drill, scoop, “vacuum-cleaner” device) to ensure success. Surface operations would take no longer than one hour.Analysis of returned samples would provide a firm basis for assessing similarities and differences between the evolution of Venus, Earth, Mars and smaller bodies such as Vesta. The Solar System provides an important case study in how two almost identical bodies, Earth and Venus, could have had such a divergent evolution. Finally, Venus, with its runaway greenhouse atmosphere, may provide data relevant to the understanding of similar less extreme processes on Earth. Venus is Earth’s planetary twin and deserves to be better studied and understood. In a wider context, analysis of returned samples from Venus would provide data relevant to the study of exoplanetary systems

Characteristics of Early-Onset vs Late-Onset Colorectal Cancer: A Review.

The incidence of early-onset colorectal cancer (younger than 50 years) is rising globally, the reasons for which are unclear. It appears to represent a unique disease process with different clinical, pathological, and molecular characteristics compared with late-onset colorectal cancer. Data on oncological outcomes are limited, and sensitivity to conventional neoadjuvant and adjuvant therapy regimens appear to be unknown. The purpose of this review is to summarize the available literature on early-onset colorectal cancer. Within the next decade, it is estimated that 1 in 10 colon cancers and 1 in 4 rectal cancers will be diagnosed in adults younger than 50 years. Potential risk factors include a Westernized diet, obesity, antibiotic usage, and alterations in the gut microbiome. Although genetic predisposition plays a role, most cases are sporadic. The full spectrum of germline and somatic sequence variations implicated remains unknown. Younger patients typically present with descending colonic or rectal cancer, advanced disease stage, and unfavorable histopathological features. Despite being more likely to receive neoadjuvant and adjuvant therapy, patients with early-onset disease demonstrate comparable oncological outcomes with their older counterparts. The clinicopathological features, underlying molecular profiles, and drivers of early-onset colorectal cancer differ from those of late-onset disease. Standardized, age-specific preventive, screening, diagnostic, and therapeutic strategies are required to optimize outcomes

Complications of dynamic graciloplasty: incidence, management, and impact on outcome.

PURPOSE: Dynamic graciloplasty can improve continence in patients with severe refractory fecal incontinence, but associated morbidity is high. The purpose of this study was to identify complications associated with dynamic graciloplasty and to characterize their treatment and impact on patient outcome. METHODS: In 121 patients enrolled in a prospective trial of 20 centers and eligible for safety analysis, all complications of dynamic graciloplasty were recorded at the time of their occurrence and followed up until resolution. Severe treatment-related complications were defined as those requiring hospitalization or surgical intervention. RESULTS: In 93 patients, 211 complications occurred. Of these, 89 (42 percent) in 61 patients were classified as severe treatment-related complications and resulted from the following: major infection, 19; minor infection, 10; thromboembolic events, 3; device performance and use, 13; pain, 16; noninfectious gracilis problems, 8; noninfectious wound-healing problems, 3; other surgery-related complications, 3. In addition, severe treatment-related complications resulted from constipation in ten and stoma creation or closure in ten. The recovery rate (full or partial) was 87 percent overall, and for severe treatment-related complications, was 92 percent. Of the types of complications, only major infections had an adverse effect on outcome. CONCLUSION: Severe complications occur frequently after dynamic graciloplasty, but are usually treatable. They often require one or more reoperations and can lead to significant delays in completion of therapy. In most cases therapy can be salvaged

Training in colorectal surgery in Europe and 20 years of the European Board of Surgical Qualification coloproctology examination.

Training in colorectal surgery across Europe is not yet standardized. The European Board of Surgical Qualification (EBSQ) coloproctology examination has been held annually since 1998. The aims of this study were to illustrate the current situation of coloproctology specialization in Europe and to analyse the EBSQ examinations held over the last 20 years. A survey, focused on current training and education in colorectal surgery in Europe, was conducted among all national representatives of the European Society of Coloproctology (ESCP) in 2018. Candidate demographics (1998-2018) and the results of the EBSQ examination (2007-2018) were analysed. In Europe, there are currently 26 national colorectal societies, 27 national annual colorectal meetings, 16 national specialized training programmes and 13 national colorectal fellowships. Six countries have board certification in colorectal surgery and five a dedicated examination. During the last 20 years, 475 candidates from 29 countries, of whom 88 (19%) were women, passed the EBSQ examination. The pass rate was higher in younger applicants (< 42 years, P = 0.01). The success rate was higher for candidates with academic experience (more than five publications or presentations) and with an academic title (thesis) (P = 0.01). Colorectal surgical training is still not standardized in Europe, although efforts have been made to recognize colorectal surgery as an independent speciality. The number of holders of the EBSQ Diploma has increased over the years, demonstrating the acceptance of the examination among European surgeons. Young candidates with an academic profile are the most successful

Sacral nerve stimulation for faecal incontinence in patients with previous partial spinal injury including disc prolapse

BACKGROUND: This study examined the use of sacral nerve stimulation (SNS) to treat faecal incontinence in patients with partial spinal injury. METHODS: Patients selected for SNS had experienced more than one episode of faecal incontinence per week to liquid or solid stool for more than 1 year and had failed maximal conservative treatment. All patients had an intact external anal sphincter. RESULTS: Temporary SNS was performed in 13 patients (median age 58.5 (range 39-73) years). The spinal insults were disc prolapse (six), trauma (four), spinal stenosis (one) or occurred during neurosurgery (two). Twelve patients (eight women and four men) had successful temporary stimulation and proceeded to permanent implantation. The median follow-up time was 12 (range 6-24) months. The mean(s.d.) number of episodes of incontinence decreased from 9.33(7.64) per week at baseline to 2.39(3.69) at last follow-up (P = 0.012). The number of days per week with incontinence and staining decreased significantly (both P < 0.001). Ability to defer defaecation improved from a median of not being able to defer (range 0-1 min) to being able to defer for 5-15 (range 0 to over 15) min (P = 0.022). CONCLUSION: SNS can benefit patients with faecal incontinence following partial spinal injury. Copyright (c) 2005 British Journal of Surgery Society Ltd. Published by John Wiley & Sons, Ltd