Chapter 6: The Breadth and Limits of Life on Earth.

Scientific ideas about the potential existence of life elsewhere in the universe are predominantly informed by knowledge about life on Earth. Over the past ∼4 billion years, life on Earth has evolved into millions of unique species. Life now inhabits nearly every environmental niche on Earth that has been explored. Despite the wide variety of species and diverse biochemistry of modern life, many features, such as energy production mechanisms and nutrient requirements, are conserved across the Tree of Life. Such conserved features help define the operational parameters required by life and therefore help direct the exploration and evaluation of habitability in extraterrestrial environments. As new diversity in the Tree of Life continues to expand, so do the known limits of life on Earth and the range of environments considered habitable elsewhere. The metabolic processes used by organisms living on the edge of habitability provide insights into the types of environments that would be most suitable to hosting extraterrestrial life, crucial for planning and developing future astrobiology missions. This chapter will introduce readers to the breadth and limits of life on Earth and show how the study of life at the extremes can inform the broader field of astrobiology.

Chapter 1: The Astrobiology Primer 3.0.

The Astrobiology Primer 3.0 (ABP3.0) is a concise introduction to the field of astrobiology for students and others who are new to the field of astrobiology. It provides an entry into the broader materials in this supplementary issue of Astrobiology and an overview of the investigations and driving hypotheses that make up this interdisciplinary field. The content of this chapter was adapted from the other 10 articles in this supplementary issue and thus represents the contribution of all the authors who worked on these introductory articles. The content of this chapter is not exhaustive and represents the topics that the authors found to be the most important and compelling in a dynamic and changing field.

A multi-centre, double-blind, 12-week, randomized, placebo-controlled trial of adjunctive N-Acetylcysteine for treatment-resistant PTSD.

BACKGROUND: PTSD may involve oxidative stress, and N-acetylcysteine (NAC) may reduce the impact of oxidative stress in the brain. This study aims to investigate the efficacy of adjuvant NAC in people with treatment-resistant PTSD. METHODS: A multicentre, randomised, double-blind, placebo-controlled trial for adults with PTSD unresponsive to first-line treatment. The intervention was either oral NAC 2.7 g/day or placebo for 12 weeks. The primary outcome was change in Clinician-Administered PTSD Scale for DSM-5 (CAPS-5) at 12 weeks compared with baseline. Secondary outcomes included depression and substance craving. Follow-up measures were obtained at 16 and 64-weeks. RESULTS: 133 patients were assessed, with 105 randomised; 81 participants completed the 12-week trial, 79 completed week-16 follow-up, and 21 completed week-64 follow-up. There were no significant differences between those taking NAC and those taking placebo in CAPS-5 scores at week 12, nor in secondary outcomes. Significant between-group differences were observed at week 64 in craving duration (Cohen's d = 1.61) and craving resistance (Cohen's d = 1.03), both in favour of NAC. CONCLUSION: This was the first multicentre, double-blind, randomised, placebo-controlled trial of adjunctive NAC for treatment-resistant PTSD. No benefit of NAC was observed in this group beyond that provided by placebo at end of the trial. TRIAL REGISTRATION: ACTRN12618001784202, retrospectively registered 31/10/2018, URL: http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376004.

Characterizing the Piezosphere: The Effects of Decompression on Microbial Growth Dynamics.

The extent to which the full diversity of the subsurface microbiome can be captured via cultivation is likely hindered by the inevitable loss of cellular viability from decompression during sampling, enrichment, and isolation. Furthermore, the pressure tolerance of previously isolated strains that span surface and subsurface ecosystems can shed light into microbial activity and pressure adaptation in these transition zones. However, assessments of the effects of elevated pressure on the physiology of piezotolerant and piezosensitive species may be biased by high-pressure enrichment techniques. Here, we compared two high-pressure cultivation techniques-one that requires decompression of the whole cultures during sampling and one that employs the previously described isobaric PUSH devices-to explore the effects of repeated decompression during incubations performed to characterize isolates from deep environments. Two model sulfate-reducing prokaryotes were used to test the effects of decompression/repressurization cycles on growth rates, cell yields, and pressure tolerance. The mesophilic bacterium Desulfovibrio salexigens was cultivated from 0.1 to 50 MPa, and the hyperthermophilic archaeon Archaeoglobus fulgidus was tested from 0.1 to 98 MPa. For both cultivation methods, D. salexigens showed exponential growth up to 20 MPa, but faster growth rates were observed for isobaric cultivation. Furthermore, at 30 MPa minor growth was observed in D. salexigens cultures only for isobaric conditions. Isobaric conditions also extended exponential growth of A. fulgidus to 60 MPa, compared to 50 MPa when cultures were decompressed during subsampling. For both strains, growth rates and cell yields decreased with increasing pressures, and the most pronounced effects of decompression were observed at the higher end of the pressure ranges. These results highlight that repeated decompression can have a significant negative impact on cell viability, suggesting that decompression tolerance may depend on habitat depth. Furthermore, sampling, enrichment, and cultivation in isobaric devices is critical not only to explore the portion of the deep biosphere that is sensitive to decompression, but also to better characterize the pressure limits and growth characteristics of piezotolerant and piezosensitive species that span surface and subsurface ecosystems.

Smartphone-delivered multicomponent lifestyle medicine intervention for depressive symptoms: A randomized controlled trial.

OBJECTIVE: To evaluate the efficacy and credibility of a smartphone-delivered multicomponent lifestyle medicine (LM) intervention, Lifestyle Hub, as a primary modality for managing depressive symptoms in an adult Chinese population. METHOD: Participants with at least a moderate level of depressive symptoms (n = 79), as indicated by a Patient Health Questionnaire-9 score of ≥10, were randomly assigned to an LM intervention group (LMG; n = 39; eight weekly sessions) or a waitlist control group (WLG; n = 40). RESULTS: The intention-to-treat analysis revealed significant improvements in depressive symptoms (d = 0.66), generalized anxiety symptoms (d = 0.93), insomnia symptoms (d = 0.20), functional impairment (d = 0.22), and health-related quality of life (HRQoL; d = 0.11) from Week 0 (baseline) to Week 9 (immediate post-intervention assessment) in the LMG relative to the WLG. Moreover, significantly more health-promoting behaviors (overall health behaviors, health responsibility, physical activity level, nutrition, spiritual growth, and stress management) (d = 0.40-0.89) and higher levels of total activity (d = 0.55) and walking activity (d = 0.55) were found at Week 9 in the LMG relative to the WLG. However, no significant differences were observed in interpersonal relationships, vigorous and moderate exercise levels, sedentary behavior levels, or food frequency questionnaire measures at Week 9 between the LMG and the WLG. From Week 9 to Week 13 (1-month follow-up assessment), a significant within-group reduction in HRQoL (d = 0.50) and an increase in alcohol intake (d = 0.41) were observed in the LMG. CONCLUSIONS: The smartphone-delivered multicomponent LM intervention Lifestyle Hub may serve as a primary modality for managing depressive symptoms. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Systematic review: Predictors of students' success in baccalaureate nursing programs.

Nursing schools strive to select a diverse student population who are likely to succeed by ensuring timely student progression through the program and effective use of educational sources. The purpose of this systematic literature review is to explore the preadmission variables and selection criteria that predict student success in 4-year baccalaureate nursing programs in the U.S. Sixteen articles met the eligibility criteria, and six measures were used to define student success: (a) early academic success, particularly during the first and second year; (b) attrition; (c) timely completion of the program; (d) graduation; (e) performance in nursing courses; and (f) academic performance in other science courses. Typically, the core set of cognitive predictors used in the admission process in nursing schools were pre-nursing GPA, pre-nursing collegiate science GPA, and scores on standardized aptitude exams. This review suggests that it is challenging to isolate one single variable as the best predictor of student success; however, using a combination of variables can offer a reliable prediction method. More researchers should consider using a theoretical basis to guide their inquiry on this topic. Additionally, researchers should examine admission variables that are most relevant across programs.

A multi-centre, double-blind, 12-week, randomized, placebo-controlled trial to assess the efficacy of adjunctive N-Acetylcysteine for treatment-resistant PTSD: a study protocol.

BACKGROUND: Most patients with Posttraumatic Stress Disorder (PTSD) suffer residual symptoms following first-line treatment. Oxidative stress has been implicated in the pathophysiology of PTSD. N-acetylcysteine (NAC) is a precursor of the brain's primary antioxidant, glutathione, and may diminish oxidative cellular damage. An 8-week pilot study of NAC in veterans with PTSD found that symptoms were significantly reduced in the NAC group compared to placebo. This study aims to confirm these findings with a larger sample in a double-blind, placebo-controlled trial to further explore the efficacy of NAC as an adjunctive therapy in treatment-resistant PTSD. METHODS: A multicentre, randomised, double-blind, placebo-controlled trial for adult patients who still meet criteria for PTSD following first-line treatment. The intervention comprises either NAC as a fixed dose regime of 2.7 g/day (900 mg three times daily) administered orally for 12 weeks, or placebo. Standard care for PTSD will continue in addition, including other pharmacotherapies. Detailed clinical data will be collected at randomisation and weeks 4, 8, 12, 16, and 64 post-randomisation, with self-report measures completed weekly from baseline to 16 weeks and at 64 weeks post-randomisation. Blood-based biomarkers will be collected at baseline and 12 weeks to assess the mechanism of effect. The primary outcome measure will be change in Clinician-Administered PTSD Scale for DSM-5 at 12 weeks compared with baseline. Secondary outcomes will be change in quality of life, depression, anxiety, substance use and craving, and somatic symptoms. With 126 completed participants (63 per arm), the study is powered at 80% to detect a true difference in the primary outcome measure using a two-tailed analysis with alpha = 0.05, beta = 0.2. DISCUSSION: This is the first multicentre, double blind, randomised, placebo-controlled trial of adjunctive NAC for treatment-resistant PTSD. NAC has an established safety profile, is readily available and easy to administer, and has a favourable tolerability profile, therefore making it an attractive adjunctive therapy. Inclusion of blood analyses to assess potential target engagement biomarkers of oxidative stress and neuroinflammation may help gauge the biological mechanisms of effect of NAC. TRIAL REGISTRATION: ACTRN12618001784202, retrospectively registered 31/10/2018, URL: http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=376004 .

Rate and Extent of Growth of a Model Extremophile, Archaeoglobus fulgidus, Under High Hydrostatic Pressures.

High hydrostatic pressure (HHP) batch cultivation of a model extremophile, Archaeoglobus fulgidus type strain VC-16, was performed to explore how elevated pressures might affect microbial growth and physiology in the deep marine biosphere. Though commonly identified in high-temperature and high-pressure marine environments (up to 2-5 km below sea level, 20-50 MPa pressures), A. fulgidus growth at elevated pressure has not been characterized previously. Here, exponential growth of A. fulgidus was observed up to 60 MPa when supported by the heterotrophic metabolism of lactate oxidation coupled to sulfate reduction, and up to 40 MPa for autotrophic CO2 fixation coupled to thiosulfate reduction via H2. Maximum growth rates for this heterotrophic metabolism were observed at 20 MPa, suggesting that A. fulgidus is a moderate piezophile under these conditions. However, only piezotolerance was observed for autotrophy, as growth rates remained nearly constant from 0.3 to 40 MPa. Experiments described below show that A. fulgidus continues both heterotrophic sulfate reduction and autotrophic thiosulfate reduction nearly unaffected by increasing pressure up to 30 MPa and 40 MPa, respectively. As these pressures encompass a variety of subsurface marine environments, A. fulgidus serves as a model extremophile for exploring the effects of elevated pressure on microbial metabolisms in the deep subsurface. Further, these results exemplify the need for high-pressure cultivation of deep-sea and subsurface microorganisms to better reflect in situ physiological conditions.

Impact of nurse practitioners on health outcomes of Medicare and Medicaid patients.

Strengthening health care overall is essential to the health of our nation and promoting access to health care as well as controlling health care costs in a quality cost-effective manner. Nurse practitioners have demonstrated to be effective and cost-effective providers in prior research; however, many states restrict their practice. We examined for a statistically significant relationship between the level of advanced practice registered nurse (APRN) practice (full, reduced, or restricted) allowed and results of recent nationwide, state level analyses of Medicare or Medicare-Medicaid beneficiaries of potentially avoidable hospitalizations, readmission rates after inpatient rehabilitation, and nursing home resident hospitalizations and then compared them with state health outcome rankings. States with full practice of nurse practitioners have lower hospitalization rates in all examined groups and improved health outcomes in their communities. Results indicate that obstacles to full scope of APRN practice have the potential to negatively impact our nation's health. Action should be taken to remove barriers to APRN practice.

Gene expression profiling in porcine maternal infanticide: a model for puerperal psychosis.

The etiology of mental disorders remains largely unclear. Complex interactions between genetic and environmental factors are key to the development of such disorders. Puerperal psychosis is the most extreme form of postnatal mood disorder in women. Similarly, parturition in the pig can trigger extreme behavioral disturbances, including maternal infanticide. In this study, we have used a targeted cDNA microarray approach using the pig as a model to understand the genes and genetic pathways that are involved in these processes. Two subtracted cDNA libraries from porcine hypothalamus were constructed, which were enriched for genes that were over-expressed and under-expressed in the aberrant behavioral phenotype, compared to the matched control. In addition to this, a normalized library was constructed from hypothalamus and pituitary samples taken from pigs in a variety of reproductive states. The libraries were partially sequenced and combined represented approximately 5,159 different genes. Microarray analysis determined differences in gene expression between hypothalamus samples from nine matched pairs of infanticidal versus control animals, using a common reference design. Microarray analysis of variance (MAANOVA) identified 52 clones as being differentially expressed (P

Porcine maternal infanticide as a model for puerperal psychosis.

Childbirth is a period of substantial rapid biological and psychological change and a wide range of psychotic disorders can occur ranging from mild 'baby blues' to severe episodes of psychotic illnesses. Puerperal psychosis is the most extreme form of postnatal psychosis, occurring in 1 in 1,000 births. In this study, we have used the pig as an animal model for human postnatal psychiatric illness. Our aim was to identify quantitative trait loci (QTL) associated with maternal (infanticide) sow aggression. This is defined by sows attacking and killing their own newborn offspring, within 24 hr of birth. An affected sib pair whole genome linkage analysis was carried out with 80 microsatellite markers covering the 18 porcine autosomes and the X chromosome, with the aim of identifying chromosomal regions responsible for this abnormal behavior. Analysis was carried out using the non-parametric linkage test of Whittemore and Halpern, as implemented in the Merlin software. The results identified 4 QTL mapping on Sus scrofa chromosomes 2 (SSC2), 10 (SSC10), and X (SSCX). The peak regions of these QTL are syntenic to HSA 5q14.3-15, 1q32, Xpter-Xp2.1, and Xq2.4-Xqter, respectively. Several potential candidate genes lie in these regions in addition to relevant abnormal behavioral QTL, found in humans and rodents.