Characteristics and Outcomes of Hospitalized Pregnant Women With Influenza, 2010 to 2019 : A Repeated Cross-Sectional Study.

BACKGROUND: Pregnant women may be at increased risk for severe influenza-associated outcomes. OBJECTIVE: To describe characteristics and outcomes of hospitalized pregnant women with influenza. DESIGN: Repeated cross-sectional study. SETTING: The population-based U.S. Influenza Hospitalization Surveillance Network during the 2010-2011 through 2018-2019 influenza seasons. PATIENTS: Pregnant women (aged 15 to 44 years) hospitalized with laboratory-confirmed influenza identified through provider-initiated or facility-based testing practices. MEASUREMENTS: Clinical characteristics, interventions, and in-hospital maternal and fetal outcomes were obtained through medical chart abstraction. Multivariable logistic regression was used to evaluate the association between influenza A subtype and severe maternal influenza-associated outcomes, including intensive care unit (ICU) admission, mechanical ventilation, extracorporeal membrane oxygenation, or in-hospital death. RESULTS: Of 9652 women aged 15 to 44 years and hospitalized with influenza, 2690 (27.9%) were pregnant. Among the 2690 pregnant women, the median age was 28 years, 62% were in their third trimester, and 42% had at least 1 underlying condition. Overall, 32% were vaccinated against influenza and 88% received antiviral treatment. Five percent required ICU admission, 2% required mechanical ventilation, and 0.3% (n = 8) died. Pregnant women with influenza A H1N1 were more likely to have severe outcomes than those with influenza A H3N2 (adjusted risk ratio, 1.9 [95% CI, 1.3 to 2.8]). Most women (71%) were still pregnant at hospital discharge. Among 754 women who were no longer pregnant at discharge, 96% had a pregnancy resulting in live birth, and 3% experienced fetal loss. LIMITATION: Maternal and fetal outcomes that occurred after hospital discharge were not captured. CONCLUSION: Over 9 influenza seasons, one third of reproductive-aged women hospitalized with influenza were pregnant. Influenza A H1N1 was associated with more severe maternal outcomes. Pregnant women remain a high-priority target group for vaccination. PRIMARY FUNDING SOURCE: Centers for Disease Control and Prevention.

Epidemiology, Clinical Characteristics, and Outcomes of Influenza-Associated Hospitalizations in US Children Over 9 Seasons Following the 2009 H1N1 Pandemic.

BACKGROUND: Recent population-based data are limited regarding influenza-associated hospitalizations in US children. METHODS: We identified children <18 years hospitalized with laboratory-confirmed influenza during 2010-2019 seasons, through the Centers for Disease Control and Prevention's Influenza Hospitalization Surveillance Network. Adjusted hospitalization and in-hospital mortality rates were calculated, and multivariable logistic regression was conducted to evaluate risk factors for pneumonia, intensive care unit (ICU) admission, mechanical ventilation, and death. RESULTS: Over 9 seasons, adjusted influenza-associated hospitalization incidence rates ranged from 10 to 375 per 100 000 persons each season and were highest among infants <6 months old. Rates decreased with increasing age. The highest in-hospital mortality rates were observed in children <6 months old (0.73 per 100 000 persons). Over time, antiviral treatment significantly increased, from 56% to 85% (P < .001), and influenza vaccination rates increased from 33% to 44% (P = .003). Among the 13 235 hospitalized children, 2676 (20%) were admitted to the ICU, 2262 (17%) had pneumonia, 690 (5%) required mechanical ventilation, and 72 (0.5%) died during hospitalization. Compared with those <6 months of age, hospitalized children ≥13 years old had higher odds of pneumonia (adjusted odds ratio, 2.7 [95% confidence interval, 2.1-3.4], ICU admission (1.6 [1.3-1.9]), mechanical ventilation (1.6 [1.1-2.2]), and death (3.3 [1.2-9.3]). CONCLUSIONS: Hospitalization and death rates were greatest in younger children at the population level. Among hospitalized children, however, older children had a higher risk of severe outcomes. Continued efforts to prevent and attenuate influenza in children are needed.

The prevalence of cannabis use disorder in attention-deficit hyperactivity disorder: A clinical epidemiological meta-analysis.

Studies have shown that individuals with attention-deficit hyperactivity disorder (ADHD) pose an increased risk for developing substance use disorders. Increased cannabis product accessibility and recent legislative changes have led to increased cannabis consumption, thereby increasing the risk of cannabis use disorder (CUD). The present meta-analysis explored the lifetime and current prevalence of CUD in ADHD. A systematic review was conducted using the following databases: PubMed, PsycINFO and Web of Science. A total of 14 articles were included and used to estimate the aggregate lifetime and current prevalence of CUD in ADHD alongside risk ratios comparing increased risk of CUD in ADHD versus control samples. Mixed and random-effects models indicated that lifetime and current prevalence rates of CUD in ADHD populations were 26.9% and 19.2%, respectively (although prediction intervals ranged from 12.4% to 48.8% and 5.5%-39.1%, respectively). Analysis of the risk ratios indicated that those with ADHD were at 2.85- and 2.91-times greater risk of a lifetime or current diagnosis of CUD, respectively, than those in the general population. Our findings support the need for additional research on the prevalence of CUD in those with ADHD, as well as the inclusion of CUD screening in the treatment of ADHD.

Obsessive-Compulsive Disorder: A Medical School Curriculum and Textbook Review.

OBJECTIVES: We conducted a curriculum review of Canadian undergraduate medical programs to identify why aggressive obsessions (among those with obsessive-compulsive disorder [OCD]) are so often misidentified by primary care physicians and professional students. METHODS: This study involved standardized interviews with representatives from Canadian medical schools regarding the content, time, and teaching styles used to deliver curricula related to OCD. Further, we utilized a set of standardized criteria to assess the OCD content of recommended textbooks from these schools. RESULTS: Canadian medical curricula failed to provide a comprehensive picture of OCD. One-third of medical programs did not provide an example of aggressive obsessions to students, with textbook case examples centered heavily (70%) on contamination or symmetry. Only 25% of programs (and 60% of textbooks) discussed the composition of the Unacceptable Thought Domain to include aggressive, sexual, and religious obsessions. Finally, over half of medical programs failed to indicate that aggressive obsessions are ego-dystonic and do not lead people to harm themselves or others. CONCLUSION: A series of recommendations are provided for medical schools intended to improve the comprehensiveness of OCD-related training.

Item-method directed forgetting is (usually) impaired in clinical populations: A meta-analysis.

The item-method directed forgetting paradigm is a common laboratory task used to measure memory control. While impaired memory control may contribute to the development and/or maintenance of a variety of psychological disorders, comparisons between clinical and nonclinical groups using this paradigm have been inconsistent-even within the same disorder. A systematic search for related articles utilizing clinical populations was conducted revealing 823 articles of which 36 met inclusion criteria. Raw mean differences were calculated and aggregated using Bayesian multilevel random-effects models. These models revealed a significant difference in the magnitude of directed forgetting between clinical and control populations, such that clinical populations (collapsing across all disorders or combining only the critical anxiety and depression clusters) exhibited a reduced directed forgetting effect. This difference tended to be larger in clinical (as opposed to clinical-analog) populations and in older samples. These results support the notion that item-method directed forgetting provides a suitable measure of memory control sensitive to real-world control deficits and further implies that memory control deficits may contribute to mental illness (although causality remains to be determined). (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Location of brachial plexus birth injury affects functional outcomes in a rat model.

Brachial plexus birth injury (BPBI) results in shoulder and elbow paralysis with shoulder internal rotation and elbow flexion contracture as frequent sequelae. The purpose of this study was to develop a technique for measuring functional movement and examine the effect of brachial plexus injury location (preganglionic and postganglionic) on functional movement outcomes in a rat model of BPBI, which we achieved through integration of gait analysis with musculoskeletal modeling and simulation. Eight weeks following unilateral brachial plexus injury, sagittal plane shoulder and elbow angles were extracted from gait recordings of young rats (n = 18), after which rats were sacrificed for bilateral muscle architecture measurements. Musculoskeletal models reflecting animal-specific muscle architecture parameters were used to simulate gait and extract muscle fiber lengths. The preganglionic neurectomy group spent significantly less (p = 0.00116) time in stance and walked with significantly less (p < 0.05) elbow flexion and shoulder protraction in the affected limb than postganglionic neurectomy or control groups. Linear regression revealed no significant linear relationship between passive shoulder external rotation and functional shoulder protraction range of motion. Despite significant restriction in longitudinal muscle growth, normalized functional fiber excursions did not differ significantly between groups. In fact, when superimposed on a normalized force-length curve, neurectomy-impaired muscle fibers (except subscapularis) accessed regions of the curve that overlapped with the control group. Our results suggest the presence of compensatory motor control strategies during locomotion following BPBI. The clinical implications of our findings support emphasis on functional movement analysis in treatment of BPBI, as functional and passive outcomes may differ substantially.

Emotional memories are (usually) harder to forget: A meta-analysis of the item-method directed forgetting literature.

The current meta-analysis explored whether emotional memories are less susceptible to item-method directed forgetting than neutral memories. Basic analyses revealed superior memory for remember (R) than forget (F) items in both the neutral, M = 19.6%, CI95% [16.1, 23.1], and the emotional, M = 15.1%, CI95% [12.4, 17.7], conditions. Directed forgetting in either valence condition was larger for (a) words than for other stimuli; (b) recall than recognition tests; (c) studies that used recall prior to recognition testing; (d) shorter lists; and (e) studies that included buffer items. Direct comparison of the magnitude of the directed forgetting effect across neutral and emotional conditions within studies revealed relatively diminished directed forgetting of emotional items compared to neutral items, with an average difference of 4.2%, CI95% [2.0, 6.4]. However, the nature of this finding varied broadly across studies, meaning that whether - and to what degree - emotional memories are more resilient than neutral memories likely depends on the methodological features of the study in question. Moderator analyses revealed larger differences (a) in studies for which the emotional items were more arousing than the neutral items, and (b) when buffer items were included. Together, these findings suggest that emotional memories are often more resilient to intentional forgetting than neutral memories, although further research is necessary to characterize the circumstances under which these differences emerge.

Comorbid obsessive-compulsive disorder in individuals with eating disorders: An epidemiological meta-analysis.

The present study aimed to provide a precise, meta-analytic estimate of the prevalence of obsessive-compulsive disorder (OCD) amongst those with a current primary eating disorder (ED) diagnosis, and to isolate its predictors. An online search of PubMed and PsycINFO was conducted with a Boolean search phrase incorporating keywords related to OCD, EDs, comorbidity, prevalence, and epidemiology, complemented by references coded from related review articles and contact with experts in the field. Articles were included if they (a) reported an observational study examining current ED diagnoses, (b) used a semi-structured or structured diagnostic interview for OCD and ED diagnosis, (c) applied DSM or ICD criteria, (d) included adolescent or adult samples (age > 12), (e) included patient or community samples, and (f) reported lifetime or current OCD comorbidity. From the 846 articles identified, 35 lifetime and 42 current estimates were calculated. OCD prevalence was extracted from each study for each ED diagnostic category, along with eleven additional potential moderators. Analyses revealed an aggregate lifetime OCD prevalence of 13.9% CI95% [10.4 to 18.1] and current OCD prevalence of 8.7% CI95% [5.8 to 11.8] across EDs. Moderator analyses revealed the prevalence of and risk for OCD in EDs to be greatest in anorexia nervosa binge-eating purging type (ANBP). Further, OCD is most prevalent amongst patient samples than samples recruited from the community.

Comparing the effectiveness of individual and group therapy for students with symptoms of anxiety and depression: A randomized pilot study.

Objective: To examine the effectiveness of individual versus group therapy for anxiety and depression among university students. Participants: Forty-one university students experiencing moderate to severe symptoms of anxiety and/or depression participated during one of three academic semesters from 2015 to 2016. Methods: Participants were randomly assigned to either 6-weeks of individual or group therapy and completed outcome measures at pre-and-post-treatment. Results: Significant reductions in both depression and anxiety scores were found across time, with no significant difference between group and individual therapy outcomes. Exploratory analysis of attitudes toward therapy found that while individual therapy was rated more favorably than group therapy overall, attitudes toward therapy became more favorable from pre to post-treatment for all participants. An interaction showed differences in attitudes toward individual and group therapy according to participants' randomly assigned treatment. Conclusions: These findings support the increased usage of group therapy within university counseling centers, with implications for stepped care discussed.

Women Are at Greater Risk of OCD Than Men: A Meta-Analytic Review of OCD Prevalence Worldwide.

OBJECTIVE: To estimate the worldwide prevalence of obsessive-compulsive disorder (OCD), examine whether women are at greater risk than men, and explore other potential moderators of OCD prevalence to explain variability in community-based epidemiologic studies. DATA SOURCES: An electronic search of PsycINFO and PubMed was conducted until January 2017, without date or language restrictions, using the keywords OCD, epidemiology, and prevalence. The search was supplemented by articles referenced in the obtained sources and relevant reviews. STUDY SELECTION: Studies were included if they reported current, period, and/or lifetime OCD prevalence (diagnosed according to an interview based on DSM or ICD criteria) in representative community samples of adults aged 18 years or older. A total of 4,045 studies were retrieved, with 34 studies ultimately included. DATA EXTRACTION: OCD prevalence was extracted from each study alongside 9 moderators: gender, year, response rate, region, economic status, diagnostic criteria, diagnostic interview, interviewer, and age. RESULTS: The overall aggregate current, period, and lifetime OCD prevalence estimates were 1.1%, 0.8%, and 1.3%, respectively. In a typical sample, women were 1.6 times more likely to experience OCD compared to men, with lifetime prevalence rates of 1.5% in women and 1.0% in men. There was also a trend toward younger adults' being more likely to experience OCD in their lifetime than older adults. All findings demonstrated moderate heterogeneity. CONCLUSIONS: Women are typically at greater risk of experiencing OCD in their lifetime than men.

Long-Term Weight Management Using Wearable Technology in Overweight and Obese Adults: Systematic Review.

BACKGROUND: Although there are many wearable devices available to help people lose weight and decrease the rising prevalence of obesity, the effectiveness of these devices in long-term weight management has not been established. OBJECTIVE: This study aimed to systematically review the literature on using wearable technology for long-term weight loss in overweight and obese adults. METHODS: We searched the following databases: Medical Literature Analysis and Retrieval System Online, EMBASE, Compendex, ScienceDirect, Cochrane Central, and Scopus. The inclusion criteria were studies that took measurements for a period of ≥1 year (long-term) and had adult participants with a BMI >24. A total of 2 reviewers screened titles and abstracts and assessed the selected full-text papers for eligibility. The risk of bias assessment was performed using the following tools appropriate for different study types: the Cochrane risk of bias tool, Risk Of Bias In Nonrandomized Studies-of Interventions, A MeaSurement Tool to Assess systematic Reviews, and 6 questions to trigger critical thinking. The results of the studies have been provided in a narrative summary. RESULTS: We included five intervention studies: four randomized controlled trials and one nonrandomized study. In addition, we used insights from six systematic reviews, four commentary papers, and a dissertation. The interventions delivered by wearable devices did not show a benefit over comparator interventions, but overweight and obese participants still lost weight over time. The included intervention studies were likely to suffer from bias. Significant variances in objectives, methods, and results of included studies prevented meta-analysis. CONCLUSIONS: This review showed some evidence that wearable devices can improve long-term physical activity and weight loss outcomes, but there was not enough evidence to show a benefit over the comparator methods. A major issue is the challenge of separating the effect of decreasing use of wearable devices over time from the effect of the wearable devices on the outcomes. Consistency in study methods is needed in future long-term studies on the use of wearable devices for weight loss. TRIAL REGISTRATION: PROSPERO CRD42018096932; https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=96932.

The Prevalence of Anxiety Disorders During Pregnancy and the Postpartum Period: A Multivariate Bayesian Meta-Analysis.

OBJECTIVE: To estimate the prevalence of anxiety disorders in pregnant and postpartum women and identify predictors accounting for variability across estimates. DATA SOURCES: An electronic search of PsycINFO and PubMed was conducted from inception until July 2016, without date or language restrictions, and supplemented by articles referenced in the obtained sources. A Boolean search phrase utilized a combination of keywords related to pregnancy, postpartum, prevalence, and specific anxiety disorders. STUDY SELECTION: Articles reporting the prevalence of 1 or more of 8 common anxiety disorders in pregnant or postpartum women were included. A total of 2,613 records were retrieved, with 26 studies ultimately included. DATA EXTRACTION: Anxiety disorder prevalence and potential predictor variables (eg, parity) were extracted from each study. A Bayesian multivariate modeling approach estimated the prevalence and between-study heterogeneity of each disorder and the prevalence of having 1 or more anxiety disorder. RESULTS: Individual disorder prevalence estimates ranged from 1.1% for posttraumatic stress disorder to 4.8% for specific phobia, with the prevalence of having at least 1 or more anxiety disorder estimated to be 20.7% (95% highest density interval [16.7% to 25.4%]). Substantial between-study heterogeneity was observed, suggesting that "true" prevalence varies broadly across samples. There was evidence of a small (3.1%) tendency for pregnant women to be more susceptible to anxiety disorders than postpartum women. CONCLUSIONS: Peripartum anxiety disorders are more prevalent than previously thought, with 1 in 5 women in a typical sample meeting diagnostic criteria for at least 1 disorder. These findings highlight the need for anxiety screening, education, and referral in obstetrics and gynecology settings.

A Bayesian multivariate approach to estimating the prevalence of a superordinate category of disorders.

OBJECTIVE: Epidemiological research plays an important role in public health, facilitated by the meta-analytic aggregation of epidemiological trials into a single, more powerful estimate. This form of aggregation is complicated when estimating the prevalence of a superordinate category of disorders (e.g., "any anxiety disorder," "any cardiac disorder") because epidemiological studies rarely include all of the disorders selected to define the superordinate category. In this paper, we suggest that estimating the prevalence of a superordinate category based on studies with differing operationalization of that category (in the form of different disorders measured) is both common and ill-advised. Our objective is to provide a better approach. METHODS: We propose a multivariate method using individual disorder prevalences to produce a fully Bayesian estimate of the probability of having one or more of those disorders. We validate this approach using a recent case study and parameter recovery simulations. RESULTS: Our approach produced less biased and more reliable estimates than other common approaches, which were at times highly biased. CONCLUSION: Although our approach entails additional effort (e.g., contacting authors for individual participant data), the improved accuracy of the prevalence estimates obtained is significant and therefore recommended.

Meeting the mental health needs of today's college student: Reinventing services through Stepped Care 2.0.

A new stepped care model developed in North America reimagines the original United Kingdom model for the modern university campus environment. It integrates a range of established and emerging online mental health programs systematically along dimensions of treatment intensity and associated student autonomy. Program intensity can be either stepped up or down depending on level of client need. Because monitoring is configured to give both provider and client feedback on progress, the model empowers clients to participate actively in care options, decisions, and delivery. Not only is stepped care designed to be more efficient than traditional counseling services, early observations suggest it improves outcomes and access, including the elimination of service waitlists. This paper describes the new model in detail and outlines implementation experiences at 3 North American universities. While the experiences implementing the model have been positive, there is a need for development of technology that would facilitate more thorough evaluation. (PsycINFO Database Record

A meta-analysis of the worldwide prevalence of pica during pregnancy and the postpartum period.

BACKGROUND: Although pica has long been associated with pregnancy, the exact prevalence in this population remains unknown. OBJECTIVES: To estimate the prevalence of pica during pregnancy and the postpartum period, and to explain variations in prevalence estimates by examining potential moderating variables. SEARCH STRATEGY: PsycARTICLES, PsycINFO, PubMed, and Google Scholar were searched from inception to February 2014 using the keywords pica, prevalence, and epidemiology. SELECTION CRITERIA: Articles estimating pica prevalence during pregnancy and/or the postpartum period using a self-report questionnaire or interview were included. DATA COLLECTION AND ANALYSIS: Study characteristics, pica prevalence, and eight potential moderating variables were recorded (parity, anemia, duration of pregnancy, mean maternal age, education, sampling method employed, region, and publication date). Random-effects models were employed. MAIN RESULTS: In total, 70 studies were included, producing an aggregate prevalence estimate of 27.8% (95% confidence interval 22.8-33.3). In light of substantial heterogeneity within the study model, the primary focus was identifying moderator variables. Pica prevalence was higher in Africa compared with elsewhere in the world, increased as the prevalence of anemia increased, and decreased as educational attainment increased. CONCLUSIONS: Geographical region, anemia, and education were found to moderate pica prevalence, partially explaining the heterogeneity in prevalence estimates across the literature.

Hypoxia disrupts proteostasis in Caenorhabditis elegans.

Oxygen is fundamentally important for cell metabolism, and as a consequence, O2 deprivation (hypoxia) can impair many essential physiological processes. Here, we show that an active response to hypoxia disrupts cellular proteostasis - the coordination of protein synthesis, quality control, and degradation that maintains the functionality of the proteome. We have discovered that specific hypoxic conditions enhance the aggregation and toxicity of aggregation-prone proteins that are associated with neurodegenerative diseases. Our data indicate this is an active response to hypoxia, rather than a passive consequence of energy limitation. This response to hypoxia is partially antagonized by the conserved hypoxia-inducible transcription factor, hif-1. We further demonstrate that exposure to hydrogen sulfide (H2S) protects animals from hypoxia-induced disruption of proteostasis. H2S has been shown to protect against hypoxic damage in mammals and extends lifespan in nematodes. Remarkably, our data also show that H2S can reverse detrimental effects of hypoxia on proteostasis. Our data indicate that the protective effects of H2S in hypoxia are mechanistically distinct from the effect of H2S to increase lifespan and thermotolerance, suggesting that control of proteostasis and aging can be dissociated. Together, our studies reveal a novel effect of the hypoxia response in animals and provide a foundation to understand how the integrated proteostasis network is integrated with this stress response pathway.

Does Preendoscopy Rockall Score Safely Identify Low Risk Patients following Upper Gastrointestinal Haemorrhage?

Objective. To determine if preendoscopy Rockall score (PERS) enables safe outpatient management of New Zealanders with upper gastrointestinal haemorrhage (UGIH). Methods. Retrospective analysis of adults with UGIH over 59 consecutive months. PERS, diagnosis, demographics, need for endoscopic therapy, transfusion or surgery and 30-day mortality and 14-day rebleeding rate, and sensitivity and specificity of PERS for enabling safe discharge preendoscopy were calculated. Results. 424 admissions with UGIH. Median age was 74.3 years (range 19-93 years), with 55.1% being males. 30-day mortality was 4.6% and 14-day rebleeding rate was 6.0%. Intervention was required in 181 (46.6%): blood transfusion (147 : 37.9%), endoscopic intervention (75 : 19.3%), and surgery (8 : 2.1%). 42 (10.8%) had PERS = 0 with intervention required in 15 (35.7%). Females more frequently required intervention, OR 1.73 (CI: 1.12-2.69). PERS did not predict intervention but did predict 30-day mortality: each point increase equated to an increase in mortality of OR 1.46 (CI: 1.11-1.92). Taking NSAIDs/aspirin reduced 30-day mortality, OR 0.22 (CI: 0.08-0.60). Conclusion. PERS identifies 10.8% of those with UGIH as low risk but 35.7% required intervention or died. It has a limited role in assessing these patients and should not be used to identify those suitable for outpatient endoscopy.

Creating defined gaseous environments to study the effects of hypoxia on C. elegans.

Oxygen is essential for all metazoans to survive, with one known exception. Decreased O(2) availability (hypoxia) can arise during states of disease, normal development or changes in environmental conditions. Understanding the cellular signaling pathways that are involved in the response to hypoxia could provide new insight into treatment strategies for diverse human pathologies, from stroke to cancer. This goal has been impeded, at least in part, by technical difficulties associated with controlled hypoxic exposure in genetically amenable model organisms. The nematode Caenorhabditis elegans is ideally suited as a model organism for the study of hypoxic response, as it is easy to culture and genetically manipulate. Moreover, it is possible to study cellular responses to specific hypoxic O(2) concentrations without confounding effects since C. elegans obtain O(2) (and other gasses) by diffusion, as opposed to a facilitated respiratory system. Factors known to be involved in the response to hypoxia are conserved in C. elegans. The actual response to hypoxia depends on the specific concentration of O(2) that is available. In C. elegans, exposure to moderate hypoxia elicits a transcriptional response mediated largely by hif-1, the highly-conserved hypoxia-inducible transcription factor. C .elegans embryos require hif-1 to survive in 5,000-20,000 ppm O(2). Hypoxia is a general term for "less than normal O(2)". Normoxia (normal O(2)) can also be difficult to define. We generally consider room air, which is 210,000 ppm O(2) to be normoxia. However, it has been shown that C. elegans has a behavioral preference for O(2) concentrations from 5-12% (50,000-120,000 ppm O(2)). In larvae and adults, hif-1 acts to prevent hypoxia-induced diapause in 5,000 ppm O(2). However, hif-1 does not play a role in the response to lower concentrations of O(2) (anoxia, operational definition <10 ppm O(2)). In anoxia, C. elegans enters into a reversible state of suspended animation in which all microscopically observable activity ceases. The fact that different physiological responses occur in different conditions highlights the importance of having experimental control over the hypoxic concentration of O(2). Here, we present a method for the construction and implementation of environmental chambers that produce reliable and reproducible hypoxic conditions with defined concentrations of O(2). The continual flow method ensures rapid equilibration of the chamber and increases the stability of the system. Additionally, the transparency and accessibility of the chambers allow for direct visualization of animals being exposed to hypoxia. We further demonstrate an effective method of harvesting C. elegans samples rapidly after exposure to hypoxia, which is necessary to observe many of the rapidly-reversed changes that occur in hypoxia. This method provides a basic foundation that can be easily modified for individual laboratory needs, including different model systems and a variety of gasses.