Oxidative stress and insulin resistance in policemen working shifts

Negative symptoms and neurocognition in drug-naïve schizophrenia: moderating role of plasma neutrophil gelatinase-associated lipocalin (NGAL) and interferon-gamma (INF-γ)

Previous studies reported that peripheral inflammation was associated with cognitive performance and brain structure in schizophrenia. However, the moderating effect of inflammation has not been extensively studied. This study investigated whether inflammation markers moderated the association between negative symptoms and neurocognition in schizophrenia. This cross-sectional study included 137 drug-naïve schizophrenia patients (DNS) and 67 healthy controls (HC). We performed the Measurements and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) for cognitive assessment and the Positive and Negative Syndrome Scale (PANSS) for psychiatric symptoms. Plasma concentrations of interferon-gamma (IFN-γ), neutrophil gelatinase-associated lipocalin (NGAL), and nuclear factor kappa B (NF-κB) were measured. The MCCB neurocognition score, social cognition score, and total score; the plasma concentrations of NGAL, IFN-γ, and NF-κB were significantly decreased in DNS than in HC (all P's < 0.001). PANSS negative subscale (PNS), PANSS reduced expressive subdomain (RES) negatively correlated with neurocognition score (P = 0.007; P = 0.011, respectively). Plasma concentrations of IFN-γ and NGAL positively correlated with neurocognition score (P = 0.043; P = 0.008, relatively). The interactions of PNS × NGAL; PNS × IFN-γ; RES × IFN-γ accounted for significant neurocognition variance (P = 0.025; P = 0.029, P = 0.007, respectively). Simple slope analysis showed that all the above moderating effects only occurred in patients with near normal IFN-γ and NGAL levels. Plasma concentrations of IFN-γ and NGAL moderated the relationship between negative symptoms (especially RES) and neurocognition in schizophrenia. Treatment targeting inflammation may contribute to neurocognition improvement in schizophrenia.

Chrono-modulated effects of external stressors on oxidative stress and damage in humans: A scoping review on night shift work

BACKGROUND

Oxidative stress and tissue damage (OSD) play a pivotal role as an early-stage process in chronic disease pathogenesis. However, there has been little research to better understand the temporal (χρόνος[chronos]) dimensions of OSD process associated with environmental (non-genetic, including behaviors/lifestyle) and/or occupational stressors, like night shift work. OSD processes have recently attracted attention in relation to time-resolved external stressor trajectories in personalized medicine (prevention) initiatives, as they seem to interact with circadian clock systems towards the improved delineation of the early stages of (chronic) disease process.

OBJECTIVES

This work critically reviewed human studies targeting the temporal dynamics of OSD and circadian clock system's activity in response to environmental/occupational stressors; the case of night shift work was examined.

METHODS

Being a key stressor influencing OSD processes and circadian rhythm, night shift work was evaluated as part of a scoping review of research in OSD, including inflammatory and metabolic processes to determine the extent of OSD research undertaken in human populations, methodologies, tools and biomarkers used and the extent that the temporal dimensions of exposure and biological effect(s) were accounted for. Online databases were searched for papers published from 2000 onwards, resulting in the selection of 53 original publications.

RESULTS AND DISCUSSION

The majority of studies (n = 41) took place in occupational settings, while the rest were conducted in the general population or patient groups. Most occupational studies targeted outcomes of oxidative stress/damage (n = 19), followed by the combination of OSD with inflammatory response (n = 10), and studies focused on metabolic outcomes (n = 12). Only a minor fraction of the studies measured biomarkers related to circadian rhythm, such as, melatonin, its metabolite, or cortisol. Night shift work was associated with select biomarkers of OSD and inflammation, albeit with mixed results. Although much progress in delineating the biological mechanisms of OSD process has been made, an equally thorough investigation on the temporal trajectory of OSD processes as triggered by environmental/occupational stressors in human studies has yet to fully evolve.

Shift Work and Metabolic Syndrome Updates: A Systematic Review

Shift work can cause circadian cycles disturbances and misaligns the endogenous rhythms. The physiological variables are driven by the circadian system and, its misalignment, can impair the metabolic functions. Thus, the main objective of this study was to evaluate the metabolic alterations as a result of shift work and night work reported in articles published in the last 5 years, using the eligibility criteria both gender and indexed articles in English language. In order to execute this work, we perform a systematic review according to PRISMA guidelines and searched about Chronobiology Disorders and Night Work, both related to metabolism, in Medline, Lilacs, ScienceDirect and Cochrane. Cross-sectional, cohort and experimental studies with low risk of bias were included. We found a total of 132 articles, and, after the selection process, 16 articles remained to be analyzed. It was observed that shift work can cause circadian misalignment and, consequently, some metabolic parameters alterations such as an impaired glycemic control and insulin functioning, cortisol phase release, cholesterol fractions imbalance, changes in morphological indexes and melatonin secretion. There are some limitations, such as heterogenicity in used databases and the 5 years restriction period, because the effects of sleep disturbance may have been reported earlier. In conclusion, we suggest that shift work interferes with the sleep-wake cycle and eating patterns, which cause crucial physiological alterations that, together, can lead to metabolic syndrome.

Impaired Melatonin Secretion, Oxidative Stress and Metabolic Syndrome in Night Shift Work

Metabolic syndrome has been associated in many studies with working in shifts. Even if the mechanistic details are not fully understood, forced sleep deprivation and exposure to light, as happens during night shifts, or irregular schedules with late or very early onset of the working program, lead to a sleep-wake rhythm misalignment, metabolic dysregulation and oxidative stress. The cyclic melatonin secretion is regulated by the hypothalamic suprachiasmatic nuclei and light exposure. At a central level, melatonin promotes sleep and inhibits wake-signals. Beside this role, melatonin acts as an antioxidant and influences the functionality of the cardiovascular system and of different metabolic processes. This review presents data about the influence of night shifts on melatonin secretion and oxidative stress. Assembling data from epidemiological, experimental and clinical studies contributes to a better understanding of the pathological links between chronodisruption and the metabolic syndrome related to working in shifts.

Occupational Health Aspects with Special Focus on Physiological Differences between Office and Metalworkers

Physical workload adversely impacts inflammation, oxidative stress and mood in heavy workers. We compared these risk parameters between metalworkers (n = 20) and office workers (n = 30), including gender differences. Blood samples were analyzed with thirty parameters to overview endocrinology, inflammation, and psychological and oxidative stress. Despite an adequate antioxidative supply, oxidative stress occurred in metalworkers, as indicated by significantly increased peroxide and homocysteine (Hcy) levels. Moreover, increased concentrations were observed in this group regarding psychological stress and diet-related parameters. Sex-specific differences were determined for physical dimensions, dehydroepiandrosterone sulfate (DHEAS), Hcy, uric acid, triglycerides, osmolality, anti-Mullerian hormone (AMH) and testosterone. Age-associated differences were observed for DHEAS, glycosylated hemoglobin, adrenaline, AMH and testosterone. In male office workers, the body mass index was associated with increased LDL-HDL, cholesterol-HDL and homeostatic model assessment of insulin resistance (HOMA-IR). In conclusion, these results indicate increased oxidative stress and psychological stress in heavy workers independently of adequate antioxidant sustenance. The sedentary occupation of office workers, in turn, favored diseases of affluence. This might be particularly relevant for long-term occupied persons and older workers due to a hormonal shift coming along, given the risk for oxidative stress-related diseases such as cardiovascular disease, particularly in the case of males, based on their lifestyle habits.

Daily injection of melatonin inhibits insulin resistance induced by chronic mealtime shift

Shift work disorders have become an emerging concern worldwide. Shift disorders encompass a wide range of illnesses that have yet to be identified. The study focused on the relationship between shift work disorders and insulin resistance. Previously, it was reported that advancing the usual mealtime of mice triggered insulin resistance. Here, the hypothesis that chronic mealtime shifts induce oxidative damage leading to chronic diseases such as type 2 diabetes was tested. It was found that mealtime shift causes imbalances between anti-oxidative capacity and reactive oxygen species (ROS) levels, indicating increased oxidative damage during the light/rest phase. This study further demonstrated that daily supplementation of antioxidants at the appropriate time of day inhibited insulin resistance caused by chronic mealtime shifts, suggesting significant and chronic health implications for shift workers. In conclusion, it was confirmed that increased ROS levels caused by mealtime shift induce insulin resistance, which is inhibited by the antioxidant melatonin.

Relationship between shift work and age-related macular degeneration: a cross-sectional analysis of data from the 5th Korea National Health and Nutrition Examination Survey (2010-2012)

Background

Age-related macular degeneration (AMD) is the leading cause of blindness. Shift work has well-known adverse effects on health. However, few studies have investigated the relationship between shift work and AMD. This study was conducted to investigate the relationship between shift work and AMD.

Methods

This study used aggregated data from the 2010-2012 cycles of the Korea National Health and Nutrition Examination Survey. The work schedules were classified into 2 types: day work and shift work. AMD was determined using fundus photographs. The χ² test and multiple logistic regression analysis were used to assess sex-stratified relationship between shift work and AMD.

Results

The odds ratio (OR) of AMD in male shift workers was higher (1.54 [95% confidence interval, CI: 1.01-2.36]) than that in male day workers after adjusting for covariates. After dividing into subgroups of the shift work pattern, the OR of AMD in male night shift workers was higher (1.75 [95% CI: 1.07-2.85]) than that in male day workers after adjusting for covariates. However, results of the female worker group were not significant.

Conclusions

The results of this study provide limited support for the hypothesis that shift work is related to AMD. Further prospective studies are needed to define the relationship between shift work and AMD.

Metabolic health measurements of shift workers in a national cross-sectional study: Results from the Canadian Health Measures Survey

BACKGROUND

Shift work exposure may be a concern for a range of health effects, including metabolic health outcomes such as insulin resistance, high body weight, and abdominal obesity.

METHODS

We analyzed shift work and indicators of metabolic health (overweight/obesity defined by body mass index, self-reported changes in body mass index (BMI) in previous 1 and 10 years, waist circumference, waist-to-hip ratio, and insulin resistance assessed by the homeostasis model assessment 2 (HOMA-2-IR)) in the cross-sectional Canadian Health Measures Survey (CHMS). We analyzed descriptive characteristics of shift workers (regular night, evening, and rotating shift) and used multivariable linear regression to examine the association between two definitions of shift work exposure and measures of metabolic health, adjusted for age, sex, daily energy expenditure, sleep, and poor dietary quality.

RESULTS

5470 anthropometry (2637 fasting) participants in CHMS Cycles 1 and 2 were included, of whom 16.5% worked regular evening, night, or rotating shifts. Shift workers were younger and slept longer hours than non-shift workers. Bivariate associations showed inverse relationships between shift work and BMI, waist circumference, waist-to-hip ratio, and HOMA-2-IR. In adjusted analyses, BMI was inversely related to shift work, and other metabolic health outcomes showed no significant associations.

CONCLUSIONS

Healthy worker effects (including self-selection of exposure) could explain inverse relationships, particularly as the cross-sectional design only allowed assessment of current exposure. Key strengths include the population-based design and measurement of metabolic health indicators. Results underscore the importance of consideration of the health of shift workers following departure from the exposed population.

The association of energy and macronutrient intake at dinner vs breakfast with the incidence of type 2 diabetes mellitus in a cohort study: The China Health and Nutrition Survey, 1997-2011

BACKGROUND

This study aims to investigate the association of energy and macronutrient intake at dinner vs breakfast with the incidence of type 2 diabetes mellitus (T2DM).

METHODS

A total of 11 153 adults, including 811 with T2DM, completed a questionnaire about energy and macronutrient intake in the China Health and Nutrition Survey (1997-2011). The differences (Δ) in energy and macronutrient intake between dinner and breakfast (Δ = dinner - breakfast) were categorized into quintiles. Cox proportional hazards regression models were performed to explore the association between Δ and the risk of T2DM and to investigate the change of the risk when 5% total energy or energy provided by macronutrients at dinner was substituted with total energy or energy provided by macronutrients at breakfast by isocaloric substitution models.

RESULTS

After adjustment for potential confounders, compared with participants in the lowest quintile, participants in the highest quintile were more likely to develop T2DM (hazard ratio [HR]_Δenergy 1.46, 95% CI 1.13-1.87; HR_Δfat 1.85, 95% CI 1.43-2.41; HR_Δprotein 1.37, 95% CI 1.06-1.78). Isocalorically replacing 5% energy at dinner with energy at breakfast was associated with a 7% lower T2DM risk. Replacing 5% energy provided by fat at dinner with energy provided by carbohydrate, protein, and fat at breakfast was associated with a 9%, 5%, and 7% lower T2DM risk, respectively. Replacing 5% energy provided by protein at dinner with energy provided by carbohydrate or protein at breakfast was associated with a 5% lower T2DM risk.

CONCLUSIONS

Higher intake of energy, protein, and fat at dinner than at breakfast increased the risk of T2DM.

A systematic review of the relationship between night shift work and oxidative stress

Night shift workers make up an essential part of the modern workforce. However, night shift workers have higher incidences of late in life diseases and earlier mortality. Night shift workers experience circadian rhythm disruption due to working overnight. Sleep disruption is thought to increase oxidative stress, defined as an imbalance of excess pro-oxidative factors and reactive oxygen species over anti-oxidative activity. Oxidative stress can damage cells, proteins and DNA and can eventually lead to varied chronic diseases such as cancer, diabetes, cardiovascular disease, Alzheimer's and dementia. This review aimed to understand whether night shift workers were at greater risk of oxidative stress. Twelve correlational studies published in 2001-2019 were included in the review that measured the levels of oxidative stress indicators from working a single night shift as well as comparisons between those who regularly work night shifts and only day shifts. All studies had evidence to support the relationship between working night shifts and increased oxidative stress indicators. Specifically, night shift work was associated with increased DNA damage, reduced DNA repair capacity, increased lipid peroxidation, higher levels of reactive oxygen species, and to a lesser extent, a reduction in antioxidant defence. These results suggest a potential link between circadian rhythm disruption in night shift workers with oxidative stress and therefore disease. However, this review is limited by having no longitudinal or experimental studies. Further research is required to infer causality. This further research is recommended to promote the long-term health of night shift workers.

Expanding the link between circadian rhythms and redox metabolism of epigenetic control

Circadian rhythms play a central role in physiological and metabolic processes. This is mostly achieved through rhythmic regulation of myriad genes via dynamic epigenome changes. Accumulating evidence indicates that oxidative stress and redox balance are under circadian control and feedback on the clock system. Circadian perturbations induce oxidative stress accumulation and disturb redox balance. Along with these changes, epigenomic landscape changes are a remarkable hallmark of clock disruption. This review aims to summarize evidence supporting the link between the circadian clock and redox metabolism, focusing on possible connections through epigenetic mechanisms.

Association of industrial work schedules with development of metabolic syndrome, insulin resistance, and serum adipokine concentrations

Background

Association of work schedule in industrial workers with the progression of metabolic syndrome, insulin resistance, and serum adipokine concentrations is incompletely explored.

Objective

To determine the association of work schedule with the progression of metabolic syndrome, insulin resistance, and adipokine concentrations in industrial workers.

Methods

In a cross-sectional study design of industrial workers we compared metabolic syndrome, insulin resistance, and adipokines concentration between workers in the day shift (n = 52), rotational shift (n = 21), and night shift (n = 15). The international Diabetes Federation criteria were used to diagnose metabolic syndrome. We used a homeostatic model assessment of insulin resistance (HOMA-IR). Serum insulin, leptin, and adiponectin concentrations were measured using enzyme-linked immunosorbent assays. Serum glucose, triglyceride, and high-density lipoprotein cholesterol (HDL-C) concentrations were monitored using Prietest clinical chemistry reagents.

Results

The proportional difference in metabolic syndrome (0.31, 95% confidence interval [CI] 0.036-0.587, P = 0.026), median difference of leptin (0.61, 95% CI 0.186-1.034, P = 0.005), and leptin-to-adiponectin ratio (LAR; 0.45, 95% CI 0.235-0.665, P < 0.001) was significantly higher, and serum adiponectin was lower (-2.00, 95% CI -4.197 to 0.197, P = 0.07) in the night-shift workers compared with that of day-shift workers. Among rotational-shift workers, the proportional difference between metabolic syndrome (0.14, 95% CI -0.098 to 0.378, P = 0.25), median difference of leptin (0.25, 95% CI -0.124 to 0.624, P = 0.19), and LAR (0.09, 95% CI -0.099 to 0.279, P = 0.35) was higher, and serum adiponectin concentration was lower (-0.73, 95% CI -2.660 to 1.208, P = 0.46) compared with that of day-shift workers; however, the altered differences were not significant. We observed a higher proportion of difference in HOMA-IR in shift workers (night and rotation) than in day-shift workers.

Conclusion

Night-shift workers are vulnerable to a higher risk of metabolic syndrome, HOMA-IR, and adipokine changes.

A nationally representative study of law enforcement shiftwork and health outcomes

The purpose of this study was to estimate the effect of past and current rotating shift assignments on U.S. law enforcement officers' health outcomes. In a nationally representative sample of 2,867 officers, with an oversample of female officers, we estimated models of sleep quality and fatigue, physical health outcomes, and psychological health outcomes. Further, we examined individual and agency-level factors associated with officers who reported currently working a rotating shift, to investigate what patterns there may be in shift assignments. A history of rotating shift assignments was positively associated with lower sleep quality, and with hypertension, diabetes, and high cholesterol, but not with gastrointestinal disorders, perceived stress, emotional well-being, or suicidality. The associations of shiftwork with health outcomes did not vary by gender. Demographic characteristics did not predict current rotating shift assignments, but a longer history of shiftwork and more working hours did predict a current shift assignment. Attention to mitigating shift system designs as well as the effect of cumulative years of working a rotating shift for the benefit of officer health outcomes is warranted.

The Impact of Shift Type on Oxidative Stress, Inflammation, and Platelet Activation

OBJECTIVE

Rotating shift is known to disrupt circadian rhythms. The 12/24 shift system, with frequent day-night rotations and the ergonomic shift system (ESS), with 90% less rotations were compared for their impacts on oxidative stress, inflammation, and platelet activation by using pentraxin 3 (PTX3), urinary 15-isoprostane F2t, and 11-dehydrotromboxane B2 (11-DTB2).

METHODS

All tests were performed by enzyme linked immunosorbent assay (ELISA). Unpaired t test and Pearson correlation analysis were employed.

RESULTS

Two hundred twenty 12/24 and 198 ESS workers were included. Plasma PTX3 and urinary 15-isoprostane F2t levels were not different between groups. Urinary 11-DTB2 in 12/24 workers were found significantly higher compared with ESS workers (P < 0.0001). A weak but significant correlation was found between urinary 15-isoprostane F2t and urinary 11-DTB2 levels (r = 0.17, P = 0.001).

CONCLUSIONS

12/24 rotating shift was found to cause platelet activation disturbances.

A rotating light cycle promotes weight gain and hepatic lipid storage in mice

Processes involved in regulation of energy balance and intermediary metabolism are aligned to the light-dark cycle. Shift-work and high-fat diet (HFD)-induced obesity disrupt circadian rhythmicity and are associated with increased risk of nonalcoholic fatty liver disease. This study aimed to determine the effect of simulating shift work on hepatic lipid accumulation in lean and HFD mice. C57BL/6 mice fed a standard laboratory diet (SLD) or HFD for 4 wk were further allocated to a normal light (NL) cycle (lights on: 0600-1800) or rotating light (RL) cycle [3 days NL and 4 days reversed (lights on: 1800-0600) repeated] for 8 wk. Tissue was collected every 3 h beginning at 0600. HFD mice gained more weight than SLD mice, and RL mice gained more weight than NL mice. SLD-NL and HFD-NL mice, but not RL mice, were more active, had higher respiratory quotients, and consumed/expended more energy during the dark phase compared with the light phase. Blood glucose and plasma cholesterol and triglyceride concentrations were elevated in HFD and SLD-RL compared with SLD-NL mice. Hepatic glycogen was elevated in HFD compared with SLD mice. Hepatic triglycerides were elevated in SLD-RL and HFD mice compared with SLD-NL. Circadian rhythmicity of hepatic acetyl-CoA carboxylase (ACACA) mRNA was phase shifted in SLD-RL and HFD-NL and lost in HFD-RL mice. Hepatic ACACA protein was reduced in SLD-RL and HFD mice compared with SLD-NL mice. Hepatic adipose triglyceride lipase was elevated in HFD-NL compared with SLD-NL but lower in RL mice compared with NL mice irrespective of diet. In conclusion, an RL cycle model of shift work promotes weight gain and hepatic lipid storage even in lean conditions. NEW & NOTEWORTHY In this publication we describe the effects of a rotating light cycle model of shift work in lean and high-fat diet-induced obese mice on body mass, diurnal patterns of energy intake and expenditure, and hepatic lipid storage. The data indicate that modeling shift work, via a rotating light cycle, promotes weight gain and hepatic lipid accumulation even in mice on a standard laboratory diet.