Ocular effects of exposure to low-humidity environment with contact lens wear: A pilot study.

PURPOSE: To compare the ocular effects of exposure to a low-humidity environment with and without contact lens (CL) wear using various non-invasive tests. METHODS: Fourteen habitual soft CL wearers were exposed to controlled low humidity (5% relative humidity [RH]) in an environmental chamber for 90 min on two separate occasions. First, when wearing their habitual spectacles and then, on a separate visit, when wearing silicone hydrogel CLs that were fitted specifically for this purpose. All participants had adapted to the new CL prior to data collection. Three non-invasive objective measurements were taken at each visit: blinking rate, objective ocular scatter (measured using the objective scatter index) and ocular surface cooling rate (measured using a long-wave infrared thermal camera). At each visit, measurements were taken before the exposure in comfortable environmental conditions (RH: 45%), and after exposure to environmental stress (low humidity, RH: 5%). RESULTS: CL wearers showed increased blinking rate (p < 0.005) and ocular scatter (p = 0.03) but similar cooling rate of the ocular surface (p = 0.08) when compared with spectacle wear in comfortable environmental conditions. The exposure to low humidity increased the blinking rate significantly with both types of corrections (p = 0.01). Interestingly, ocular scatter (p = 0.96) and cooling rate (p = 0.73) were not significantly different before and after exposure to low humidity. There were no significant two-way interactions between correction and exposure in any of the measurements. CONCLUSIONS: CLs significantly increased the blinking rate, which prevented a quick degradation of the tear film integrity as it was refreshed more regularly. It is hypothesised that the increased blinking rate in CL wearers aids in maintaining ocular scatter quality and cooling rate when exposed to a low-humidity environment. These results highlight the importance of blinking in maintaining tear film stability.

Vulnerability to helpless behavior is regulated by the circadian clock component CRYPTOCHROME in the mouse nucleus accumbens.

The nucleus accumbens (NAc), a central component of the midbrain dopamine reward circuit, exhibits disturbed circadian rhythms in the postmortem brains of depressed patients. We hypothesized that normal mood regulation requires proper circadian timing in the NAc, and that mood disorders are associated with dysfunctions of the NAc cellular circadian clock. In mice exhibiting stress-induced depression-like behavior (helplessness), we found altered circadian clock function and high nighttime expression of the core circadian clock component CRYPTOCHROME (CRY) in the NAc. In the NAc of helpless mice, we found that higher expression of CRY is associated with decreased activation of dopamine 1 receptor-expressing medium spiny neurons (D1R-MSNs). Furthermore, D1R-MSN-specific CRY-knockdown in the NAc reduced susceptibility to stress-induced helplessness and increased NAc neuronal activation at night. Finally, we show that CRY inhibits D1R-induced G protein activation, likely by interacting with the Gs protein. Altered circadian rhythms and CRY expression were also observed in human fibroblasts from major depressive disorder patients. Our data reveal a causal role for CRY in regulating the midbrain dopamine reward system, and provide a mechanistic link between the NAc circadian clock and vulnerability to depression.

Changes in 25-hydroxyvitamin D levels post-vitamin D supplementation in people of Black and Asian ethnicities and its implications during COVID-19 pandemic: A systematic review.

BACKGROUND: People of Black and Asian ethnicities have a higher infection rate and mortality as a result of COVID-19. It has also been reported that vitamin D deficiency may play a role in this, possibly because of the multi-gene regulatory function of the vitamin D receptor. As a result, increased dietary intake and/or supplementation to attain adequate 25-hydroxyvitamin D (25(OH)D) levels could benefit people in these ethnicities. The present study aimed to review the literature examining the changes in 25(OH)D in different types of vitamin D supplementation from randomised controlled trials in this population. METHODS: This systematic review was conducted using the PRISMA guidelines. Electronic databases were systematically searched using keywords related to vitamin D supplementation in Black and Asian ethnicities. RESULTS: Eight studies were included in the review. All the included studies found that supplementation of vitamin D (D2 and D3 ), regardless of dosage, increased 25(OH)D levels compared to a placebo. All trials in which participants were vitamin D deficient at baseline showed increased 25(OH)D levels to a level considered adequate. Two studies that used food fortification yielded smaller 25(OH)D increases compared to similar studies that used oral supplementation (10.2 vs. 25.5 nmol L-1 , respectively). Furthermore, vitamin D2 supplementation yielded significantly lower 25(OH)D increases than vitamin D3 supplementation. CONCLUSIONS: Oral vitamin D supplementation may be more efficacious in increasing 25(OH)D levels than food fortification of Black and Asian ethnicities, with vitamin D3 supplementation possibly being more efficacious than vitamin D2 . It is recommended that people with darker skin supplement their diet with vitamin D3 through oral tablet modes where possible, with recent literature suggesting a daily intake of 7000-10,000 IU to be potentially protective from unfavourable COVID-19 outcomes. As a result of the paucity of studies, these findings should be treated as exploratory.

Circadian repressors CRY1 and CRY2 broadly interact with nuclear receptors and modulate transcriptional activity.

Nuclear hormone receptors (NRs) regulate physiology by sensing lipophilic ligands and adapting cellular transcription appropriately. A growing understanding of the impact of circadian clocks on mammalian transcription has sparked interest in the interregulation of transcriptional programs. Mammalian clocks are based on a transcriptional feedback loop featuring the transcriptional activators circadian locomotor output cycles kaput (CLOCK) and brain and muscle ARNT-like 1 (BMAL1), and transcriptional repressors cryptochrome (CRY) and period (PER). CRY1 and CRY2 bind independently of other core clock factors to many genomic sites, which are enriched for NR recognition motifs. Here we report that CRY1/2 serve as corepressors for many NRs, indicating a new facet of circadian control of NR-mediated regulation of metabolism and physiology, and specifically contribute to diurnal modulation of drug metabolism.

A Research Enclave in 1940s Nigeria: The Rockefeller Foundation Yellow Fever Research Institute at Yaba, Lagos, 1943-49.

This article examines the history of yellow fever research carried out in West Africa in the 1940s by Rockefeller Foundation scientists. It engages with a number of debates in the history of medical research in colonial Africa, including experimentation, the construction of the "field," and biosecurity.

Battlefield acupuncture: Opening the door for acupuncture in Department of Defense/Veteran's Administration health care.

Battlefield acupuncture is a unique auricular acupuncture procedure which is being used in a number of military medical facilities throughout the Department of Defense (DoD). It has been used with anecdotal published positive impact with warriors experiencing polytrauma, post-traumatic stress disorder, and traumatic brain injury. It has also been effectively used to treat warriors with muscle and back pain from carrying heavy combat equipment in austere environments. This article highlights the history within the DoD related to the need for nonpharmacologic/opioid pain management across the continuum of care from combat situations, during evacuation, and throughout recovery and rehabilitation. The article describes the history of auricular acupuncture and details implementation procedures. Training is necessary and partially funded through DoD and Veteran's Administration (VA) internal Joint Incentive Funds grants between the DoD and the VA for multidisciplinary teams as part of a larger initiative related to the recommendations from the DoD Army Surgeon General's Pain Management Task Force. Finally, Uniformed Services University of the Health Sciences School of Medicine and Graduate School of Nursing faculty members present how this interdisciplinary training is currently being integrated into both schools for physicians and advanced practice nurses at the Uniformed Services University of the Health Sciences. Current and future research challenges and progress related to the use of acupuncture are also presented.

Ocean acidification through the lens of ecological theory.

Ocean acidification, chemical changes to the carbonate system of seawater, is emerging as a key environmental challenge accompanying global warming and other human-induced perturbations. Considerable research seeks to define the scope and character of potential outcomes from this phenomenon, but a crucial impediment persists. Ecological theory, despite its power and utility, has been only peripherally applied to the problem. Here we sketch in broad strokes several areas where fundamental principles of ecology have the capacity to generate insight into ocean acidification's consequences. We focus on conceptual models that, when considered in the context of acidification, yield explicit predictions regarding a spectrum of population- and community-level effects, from narrowing of species ranges and shifts in patterns of demographic connectivity, to modified consumer-resource relationships, to ascendance of weedy taxa and loss of species diversity. Although our coverage represents only a small fraction of the breadth of possible insights achievable from the application of theory, our hope is that this initial foray will spur expanded efforts to blend experiments with theoretical approaches. The result promises to be a deeper and more nuanced understanding of ocean acidification'and the ecological changes it portends.

Misunderstood and underappreciated: a critical review of mental health advocacy and activism in low- and middle-income countries.

Mental health advocacy and activism have been highlighted as important in the effort towards creating environments for better mental health. However, relevant research in low- and middle-income country settings remains limited and lacks critical exploration. We seek to contribute to filling this gap by exploring driving factors behind mental health advocacy and activism efforts in low- and middle-income country settings. This review uses a critically informed thematic analysis employing conceptual frameworks of productive power to analyse peer-reviewed articles on mental health advocacy or activism over the last 20 years. We suggest that the current body of research is marred by superficial explorations of activism and advocacy, partly due to a lack of cohesion around definitions. Based on our findings, we suggest a conceptual framework to guide deeper explorations of mental health advocacy and activism. This framework identifies 'legitimacy', 'context' and 'timing' as the main dimensions to consider in understanding activism and advocacy efforts. The fact that they remain misunderstood and underappreciated creates missed opportunities for meaningful inclusion of lived experience in policy decisions and limits our understanding of how communities envision and enact change.

Are artificial intelligence chatbots a reliable source of information about contact lenses?

INTRODUCTION: Artificial Intelligence (AI) chatbots are able to explain complex concepts using plain language. The aim of this study was to assess the accuracy of three AI chatbots answering common questions related to contact lens (CL) wear. METHODS: Three open access AI chatbots were compared: Perplexity, Open Assistant and ChatGPT 3.5. Ten general CL questions were asked to all AI chatbots on the same day in two different countries, with the questions asked in Spanish from Spain and in English from the U.K. Two independent optometrists with experience working in each country assessed the accuracy of the answers provided. Also, the AI chatbots' responses were assessed if their outputs showed any bias towards (or against) any eye care professional (ECP). RESULTS: The answers obtained by the same AI chatbots were different in Spain and the U.K. Also, statistically significant differences were found between the AI chatbots for accuracy. In the U.K., ChatGPT 3.5 was the most and Open Assistant least accurate (p < 0.01). In Spain, Perplexity and ChatGPT were statistically more accurate than Open Assistant (p < 0.01). All the AI chatbots presented bias, except ChatGPT 3.5 in Spain. CONCLUSIONS: AI chatbots do not always consider local CL legislation, and their accuracy seems to be dependent on the language used to interact with them. Hence, at this time, although some AI chatbots might be a good source of information for general CL related questions, they cannot replace an ECP.

Contextual awareness, response and evaluation (CARE) of diabetes in poor urban communities in Ghana: the CARE diabetes project qualitative study protocol.

Diabetes remains a major, global clinical and public health threat with consistent rises in prevalence around the world over the past four decades. Two-thirds of the projected increases in global diabetes prevalence to 2045 are expected to come from low- and middle-income countries, including those in sub-Saharan Africa. Ghana is typical of this trend. However, there are gaps in evidence regarding the appropriate development of interventions and well-targeted policies for diabetes prevention and treatment that pay due attention to relevant local conditions and influences. Due consideration to community perspectives of environmental influences on the causes of diabetes, access to appropriate health services and care seeking for diabetes prevention and management is warranted, especially in urban settings. The 'Contextual Awareness, Response and Evaluation (CARE): Diabetes in Ghana' project is a mixed methods study in Ga Mashie, Accra. An epidemiological survey is described elsewhere. Six qualitative studies utilising a range of methodologies are proposed in this protocol to generate a contextual understanding of type 2 diabetes mellitus in an urban poor population. They focus on community, care provider, and policy stakeholder perspectives with a focus on food markets and environmental influences, the demand and supply of health services, and the history of the Ga Mashie community and its inhabitants. The results will be shared with the community in Ga Mashie and with health policy stakeholders in Ghana and other settings where the findings may be usefully transferable for the development of community-based interventions for diabetes prevention and control.

Main findings: Diabetes is a major, global health threat with rises in incidence projected in low- and middle-income countries, including Ghana, yet evidence gaps remain related to the development of contextually appropriate interventions and policies for diabetes prevention and treatment.Added knowledge: Sitting within a larger, mixed methods study entitled 'Contextual Awareness, Response and Evaluation (CARE): Diabetes in Ghana', this study design paper introduces six complementary qualitative studies designed to address this gap in Ga Mashie, Accra.Global health impact for policy and action: Robust methods to describe diabetes burdens and dissemination of evidence are crucial for health policy and impact.

Advantages of Short-Segment Fusion in the Surgical Management of Thoracolumbar Traumatic Fractures: A Case Series and Review of the Literature.

INTRODUCTION: Spine trauma is a common pathology that frequently requires neurosurgical intervention. Few studies have examined short-segment, 360-degree stabilization of traumatic thoracolumbar fractures. METHODS: A retrospective review was completed of adult and pediatric patients who underwent surgical correction for thoracolumbar fractures between December 2011 and December 2021. RESULTS: Forty patients met the inclusion criteria. The majority of patients presented with an American Spinal Injury Association (ASIA) score of D (n = 11) or E (n = 21). The most common level of injury was L1 (n = 20). The average length of stay was 11.7 days. Postoperatively, two patients had pulmonary emboli or deep venous thrombosis, and two had surgical site infections. Most patients were discharged to home (n = 21) or acute rehab (n = 14). The fusion rate at six months was 97.5%. Neurologically, all patients regained ambulation by >18 months follow-up. For the ASIA scale, most had a score of D (n = 4) or E (n = 32) at six months. The same trend was observed with the Frankel score, where most patients had either D (n = 5) or E (n = 31), improving to only two having a score of D at >18 months. CONCLUSIONS: Corpectomy followed by posterior fusion has a number of biomechanical benefits. This construct permits circumferential decompression, larger surface area for fusion, improved reconstitution of vertebral body height, reduced kyphosis, and an overall shorter segment. This results in fewer levels needing to be fused while enabling the greatest changes of successful fusion.

Daily running enhances molecular and physiological circadian rhythms in skeletal muscle.

OBJECTIVE: Exercise is a critical component of a healthy lifestyle and a key strategy for the prevention and management of metabolic disease. Identifying molecular mechanisms underlying adaptation in response to chronic physical activity is of critical interest in metabolic physiology. Circadian rhythms broadly modulate metabolism, including muscle substrate utilization and exercise capacity. Here, we define the molecular and physiological changes induced across the daily cycle by voluntary low intensity daily exercise. METHODS: Wildtype C57BL6/J male and female mice were housed with or without access to a running wheel for six weeks. Maximum running speed was measured at four different zeitgeber times (ZTs, hours after lights on) using either electrical or manual stimulation to motivate continued running on a motorized treadmill. RNA isolated from plantaris muscles at six ZTs was sequenced to establish the impact of daily activity on genome-wide transcription. Patterns of gene expression were analyzed using Gene Set Enrichment Analysis (GSEA) and Detection of Differential Rhythmicity (DODR). Blood glucose, lactate, and ketones, and muscle and liver glycogen were measured before and after exercise. RESULTS: We demonstrate that the use of mild electrical shocks to motivate running negatively impacts maximum running speed in mice, and describe a manual method to motivate running in rodent exercise studies. Using this method, we show that time of day influences the increase in exercise capacity afforded by six weeks of voluntary wheel running: when maximum running speed is measured at the beginning of the nighttime active period in mice, there is no measurable benefit from a history of daily voluntary running, while maximum increase in performance occurs at the end of the night. We show that daily voluntary exercise dramatically remodels the murine muscle circadian transcriptome. Finally, we describe daily rhythms in carbohydrate metabolism associated with the time-dependent response to moderate daily exercise in mice. CONCLUSIONS: Collectively, these data indicate that chronic nighttime physical activity dramatically remodels daily rhythms of murine muscle gene expression, which in turn support daily fluctuations in exercise performance.

The Risk of COVID-19 Related Hospitalsation, Intensive Care Unit Admission and Mortality in People With Underlying Asthma or COPD: A Systematic Review and Meta-Analysis.

Background: Several underlying diseases have been associated with unfavorable COVID-19 related outcomes including asthma and Chronic Obstructive Pulmonary Disease (COPD), however few studies have reported risks that are adjusted for confounding variables. This study aimed to examine the adjusted risk of COVID-19 related hospitalsation, intensive care unit (ICU) admission, and mortality in patients with vs. without asthma or COPD. Methods: A systematic review of major databases was undertaken for studies published between 1/12/2019 and 19/4/2021. Studies reporting the adjusted (for one or more confounder) risks of either hospitalsation, ICU admission, or mortality in asthmatics or COPD patients (control group = no asthma or no COPD) were identified. Risk of bias was determined via the QUIPS tool. A random effect meta-analysis was undertaken. Findings: 37 studies were eligible for analysis, with a total of 1,678,992 participants. The pooled ORs of COVID-19 hospitalsation in subjects with asthma and COPD was 0.91 (95% CI 0.76-1.09) and 1.37 (95% CI 1.29-1.46), respectively. For ICU admission, OR in subjects with asthma and COPD was 0.89 (95% CI 0.74-1.07) and 1.22 (95% CI 1.04-1.42), respectively. For mortality, ORs were 0.88 (95% CI 0.77-1.01) and 1.25 (95% CI 1.08-1.34) for asthma and COPD, respectively. Further, the pooled risk of mortality as measured via Cox regression was 0.93 (95% CI 0.87-1.00) for asthma and 1.30 (95% CI 1.17-1.44) for COPD. All of these findings were of a moderate level of certainty. Interpretation: COPD was significantly associated with COVID-19 related hospital admission, ICU admission, and mortality. Asthma was not associated with negative COVID-19 related health outcomes. Individuals with COPD should take precautions to limit the risk of COVID-19 exposure to negate these potential outcomes. Limitations include differing population types and adjustment for differing cofounding variables. Practitioners should note these findings when dealing with patients with these comorbidities. Review Protocol Registration: https://www.crd.york.ac.uk/prospero/.

Sore eyes as the most significant ocular symptom experienced by people with COVID-19: a comparison between pre-COVID-19 and during COVID-19 states.

OBJECTIVE: Conjunctivitis has been reported in people suffering from COVID-19. However, many ocular symptoms are associated with the term 'conjunctivitis' which may be misleading. It is also unknown whether ocular symptoms were different in chronic sufferers of anterior eye diseases, when they were experienced or how long they lasted for compared with other COVID-19 symptoms. METHODS: An online structured questionnaire obtained self-report data from people who had a confirmed diagnosis of COVID-19. Data for the type, frequency and duration of different COVID-19 symptoms were ascertained. Anterior eye symptoms experienced by participants in the pre-COVID-19 state were compared with during the COVID-19 state. RESULTS: Data from 83 participants showed that the most reported COVID-19 symptoms were dry cough (66%), fever (76%), fatigue (90%) and loss of smell/taste (70%). The three most common ocular symptoms experienced by participants were photophobia (18%), sore eyes (16%) and itchy eyes (17%). The frequency of sore eyes was significantly higher (p=0.002) during COVID-19 state (16%) compared with pre-COVID-19 state (5%). There were no differences between males and females (p>0.05). 81% of participants reported to have experienced ocular symptoms within 2 weeks of other COVID-19 symptoms, and 80% reported they lasted for less than 2 weeks. CONCLUSION: The most significant ocular symptom experienced by people suffering from COVID-19 was sore eyes. Other symptoms associated with other types of conjunctivitis, such as mucous discharge and gritty eyes linked to bacterial infection, did not reach significance. The term 'conjunctivitis' is too broad and should be used with caution.

Cryptochromes Suppress HIF1α in Muscles.

Muscles preferentially utilize glycolytic or oxidative metabolism depending on the intensity of physical activity. Transcripts required for carbohydrate and lipid metabolism undergo circadian oscillations of expression in muscles, and both exercise capacity and the metabolic response to exercise are influenced by time of day. The circadian repressors CRY1 and CRY2 repress peroxisome proliferator-activated receptor delta (PPARδ), a major driver of oxidative metabolism and exercise endurance. CRY-deficient mice exhibit enhanced PPARδ activation and greater maximum speed when running on a treadmill but no increase in exercise endurance. Here we demonstrate that CRYs limit hypoxia-responsive transcription via repression of HIF1α-BMAL1 heterodimers. Furthermore, CRY2 appeared to be more effective than CRY1 in the reduction of HIF1α protein steady-state levels in primary myotubes and quadriceps in vivo. Finally, CRY-deficient myotubes exhibit metabolic alterations consistent with cryptochrome-dependent suppression of HIF1α, which likely contributes to circadian modulation of muscle metabolism.

Conceptualising metabolic disorder in Southern Africa: Biology, history and global health.

This paper traces the history of the concept of metabolic disorder in global health and its application to the collection of health metrics relating to the 'epidemic' of non-communicable diseases in Southern Africa, with a focus on Malawi. Although the contemporary science of metabolism points to complexity and contingency, the application of a simplified version of 'metabolic disorder' or 'metabolic syndrome' as the supposed central driver of non-communicable disease in low- and middle-income countries runs the risk of obscuring the ways in which local circumstances and histories interact with global forces to produce epidemiological change. The paper discusses health data collection and its interpretation in Malawi to demonstrate how the use of this concept has led to a narrowing of the category of non-communicable disease and a neglect of the role of infectious disease in producing chronic conditions. Finally, the paper points to alternative approaches which might yield a better understanding of pressing health problems.

Isolation and Differentiation of Primary Myoblasts from Mouse Skeletal Muscle Explants.

Primary myoblasts are undifferentiated proliferating precursors of skeletal muscle. They can be cultured and studied as muscle precursors or induced to differentiate into later stages of muscle development. The protocol provided here describes a robust method for the isolation and culture of a highly proliferative population of myoblast cells from young adult mouse skeletal muscle explants. These cells are useful for the study of the metabolic properties of skeletal muscle of different mouse models, as well as in other downstream applications such as transfection with exogenous DNA or transduction with viral expression vectors. The level of differentiation and metabolic profile of these cells depends on the length of exposure, and composition of the media used to induce myoblast differentiation. These methods provide a robust system for the study of mouse muscle cell metabolism ex vivo. Importantly, unlike in vivo models, the methods described here provide a cell population that can be expanded and studied with high levels of reproducibility.

Reframing NCDs? An analysis of current debates.

There have been many debates in recent years as to whether the communicable disease versus non-communicable disease (NCD) division is a meaningful one in disease classification. Several critiques have been raised about the framing of NCDs, regarding not only the prominent role that infections play in the aetiology of NCDs, but also the communicability of many social determinants of NCDs and the individualistic, 'lifestyle' framing of NCDs that tends to focus on health behaviours to the neglect of socio-political, environmental, and structural determinants of health. In this paper, we give a historical overview of the usage of the NCD terminology and analyse some of the recent debates regarding the naming and framing of NCDs. We argue that a lack of reflection on the assumptions underlying the naming and framing of NCDs may lead to the collection of insufficient epidemiological data, the development of inappropriate interventions and the provision of inadequate care. Work in social epidemiology, health promotion, medical anthropology, demography, and other fields may provide insights into the ways in which efforts targeting NCDs may be reframed to improve impact and efficacy. In addition, concepts such as multimorbidity and syndemics, frameworks such as ecosocial theory and approaches based in the social sciences may provide a way forward in the conceptualization of disease.

Phosphorylation of CRY1 Serine 71 Alters Voluntary Activity but Not Circadian Rhythms In Vivo.

Circadian clocks allow organisms to anticipate repetitive changes in their environment such as food availability, temperature, and predation. While they most clearly manifest at the behavioral level, driving sleep-wake cycles, for example, they also provide critical temporal regulation at the level of individual tissues. Circadian clocks within organs act to ensure that each tissue is functioning in a coordinated manner to anticipate the needs of the organism as a whole but also allow for adaptation of organs to their local environment. One critical aspect of this environment is energy availability, which is communicated at the cellular level via changes in metabolites such as ATP, calcium, and NADH. AMP-activated protein kinase (AMPK) is both sensitive to fluctuations in secondary metabolites and capable of resetting the circadian clock via destabilization of the core clock components CRY and PER. Phosphorylation of serine 71 of CRY1 by AMPK destabilizes CRY1 by decreasing its interaction with binding partner PER2, thus enabling greater association with the SCF complex substrate adaptor FBXL3. Here, we describe a transgenic mouse harboring germline mutation of CRY1 serine 71 to alanine. Unexpectedly, this mutation does not affect the steady-state level of CRY1 protein in mouse livers or quadriceps. We also did not detect changes in either behavioral or molecular circadian rhythms, but female Cry1S71A mice exhibit decreased voluntary locomotor activity compared with wild-type littermates. Together, these findings suggest that phosphorylation of CRY1 serine 71 is not required for the regulation of circadian rhythms under normal physiological conditions. However, it may be involved in responding to metabolic challenges or in other aspects of physiology that contribute to voluntary activity levels.