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Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week.

ABSTRACT: The weekend effect hypothesis proposes that captive primates are more likely to give birth during times of low disturbance and reduced staff activity. The hypothesis specifically predicts that laboratory-housed primates will be more likely to give birth during the weekend than weekdays when staff activity is reduced. To date, support for the weekend effect hypothesis has been mixed and based on studies with relatively few subjects. To further examine the hypothesis, we analyzed the birthing patterns of three genera of laboratory-housed primates: squirrel monkeys (Saimiri species, N?=?2,090 births), owl monkeys (Aotus species, N?=?479 births), and rhesus macaques (Macaca mulatta, N?=?2,047 births). Contrary to predictions derived from the weekend effect hypothesis, the frequencies of births during weekends for all taxa were not significantly different from rates that would be expected by chance. However, while there was no variance across days of the week, all three taxa gave birth at nighttime, when staff was absent. This parallels reports of births in wild and captive monkeys, both diurnal and nocturnal, which are more likely to give birth during the night; plausibly a time when the environmental and social disturbance is lowest and the mother is safest to bond with her newborn infant. As all births occurred at night, we also explored the relationship between the lunar cycle and the timing of births timing. While the diurnal primates (i.e., Saimiri and Macaca) were no more likely to give birth on "bright" nights than "dark" nights, owl monkeys (Aotus) had a much higher frequency of births on bright nights than darker ones, and at rates that deviated from chance. Our data provide a more detailed understanding on how the environment may influence captive monkey births but do not support the oft-cited weekend effect hypothesis.

SUBMITTER: Hopper LM

PROVIDER: S-EPMC6667286 | biostudies-literature | 2019 Jul

REPOSITORIES: biostudies-literature

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Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week.

Hopper Lydia M LM Fernandez-Duque Eduardo E Williams Lawrence E LE

American journal of primatology 20190709 7

The weekend effect hypothesis proposes that captive primates are more likely to give birth during times of low disturbance and reduced staff activity. The hypothesis specifically predicts that laboratory-housed primates will be more likely to give birth during the weekend than weekdays when staff activity is reduced. To date, support for the weekend effect hypothesis has been mixed and based on studies with relatively few subjects. To further examine the hypothesis, we analyzed the birthing patt ...[more]

PMID: 31287186

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Project description:BACKGROUND:The concept of a weekend effect, poorer outcomes for patients admitted to hospitals at the weekend is not new, but is the focus of debate in England. Many studies have been published which consider outcomes for patients on admitted at the weekend. This systematic review and meta-analysis aims to estimate the effect of weekend admission on mortality in UK hospitals. METHODS:This is a systematic review and meta-analysis of published studies on the weekend effect in UK hospitals. We used EMBASE, MEDLINE, HMIC, Cochrane, Web of Science and Scopus to search for relevant papers. We included systematic reviews, randomised controlled trials and observational studies) on patients admitted to hospital in the UK and published after 2001. Our outcome was death; studies reporting mortality were included. Reviewers identified studies, extracted data and assessed the quality of the evidence, independently and in duplicate. Discrepancy in assessment was considered by a third reviewer. All meta-analyses were performed using a random-effects meta-regression to incorporate the heterogeneity into the weighting. RESULTS:Forty five articles were included in the qualitative synthesis. 53% of the articles concluded that outcomes for patients either undergoing surgery or admitted at the weekend were worse. We included 39 in the meta-analysis which contributed 50 separate analyses. We found an overall effect of 1.07 [odds ratio (OR)] (95%CI:1.03-1.12), suggesting that patients admitted at the weekend had higher odds of mortality than those admitted during the week. Sub-group analyses suggest that the weekend effect remained when measures of case mix severity were included in the models (OR:1.06 95%CI:1.02-1.10), but that the weekend effect was not significant when clinical registry data was used (OR:1.03 95%CI: 0.98-1.09). Heterogeneity was high, which may affect generalisability. CONCLUSIONS:Despite high levels of heterogeneity, we found evidence of a weekend effect in the UK, even after accounting for severity of disease. Further work is required to examine other potential explanations for the "weekend effect" such as staffing levels and other organisational factors. TRIAL REGISTRATION:PROSPERO International Prospective Register of Systematic Reviews -registration number: CRD42016041225 .

Project description:BackgroundFor potential future human missions to the Moon or Mars and sustained presence in the International Space Station, a safe enclosed habitat environment for astronauts is required. Potential microbial contamination of closed habitats presents a risk for crewmembers due to reduced human immune response during long-term confinement. To make future habitat designs safer for crewmembers, lessons learned from characterizing analogous habitats is very critical. One of the key issues is that how human presence influences the accumulation of microorganisms in the closed habitat.ResultsMolecular technologies, along with traditional microbiological methods, were utilized to catalog microbial succession during a 30-day human occupation of a simulated inflatable lunar/Mars habitat. Surface samples were collected at different time points to capture the complete spectrum of viable and potential opportunistic pathogenic bacterial population. Traditional cultivation, propidium monoazide (PMA)-quantitative polymerase chain reaction (qPCR), and adenosine triphosphate (ATP) assays were employed to estimate the cultivable, viable, and metabolically active microbial population, respectively. Next-generation sequencing was used to elucidate the microbial dynamics and community profiles at different locations of the habitat during varying time points. Statistical analyses confirm that occupation time has a strong influence on bacterial community profiles. The Day 0 samples (before human occupation) have a very different microbial diversity compared to the later three time points. Members of Proteobacteria (esp. Oxalobacteraceae and Caulobacteraceae) and Firmicutes (esp. Bacillaceae) were most abundant before human occupation (Day 0), while other members of Firmicutes (Clostridiales) and Actinobacteria (esp. Corynebacteriaceae) were abundant during the 30-day occupation. Treatment of samples with PMA (a DNA-intercalating dye for selective detection of viable microbial population) had a significant effect on the microbial diversity compared to non-PMA-treated samples.ConclusionsStatistical analyses revealed a significant difference in community structure of samples over time, particularly of the bacteriomes existing before human occupation of the habitat (Day 0 sampling) and after occupation (Day 13, Day 20, and Day 30 samplings). Actinobacteria (mainly Corynebacteriaceae) and Firmicutes (mainly Clostridiales Incertae Sedis XI and Staphylococcaceae) were shown to increase over the occupation time period. The results of this study revealed a strong relationship between human presence and succession of microbial diversity in a closed habitat. Consequently, it is necessary to develop methods and tools for effective maintenance of a closed system to enable safe human habitation in enclosed environments on Earth and beyond.

Dataset Information

Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week.

Publications

Testing the weekend effect hypothesis: Time of day and lunar phase better predict the timing of births in laboratory-housed primates than day of week.

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