Atrial fibrillation hospitalization is associated with exposure to fine particulate air pollutants.

BACKGROUND: Although air pollutants have been associated with cardiopulmonary mortality, their effects on the occurrence of atrial fibrillation (Afib) remain unclear. This study examined the association between ambient air pollutants and Afib occurrence. METHODS: Using a representative sample from the National Health Insurance Database of Taiwan, we applied a case-crossover study design to explore the associations between air pollutants and patients hospitalized with Afib from 2006 to 2011. The event day was when a patient was hospitalized with Afib, and the control days were the same days of the following weeks of the same month. The association between Afib occurrence and levels of ambient air pollutants (including particulate matter [PM] 2.5 PM10, NO2, SO2, and O3) was examined after adjusting for temperature and relative humidity. A two-pollutant model was used to examine the effect of the second pollutant when the first pollutant was determined to be significantly related to Afib. RESULTS: During 2006-2011, 670 patients hospitalized with the first onset of Afib were identified. The occurrence of Afib was associated with PM2.5, in which a 22% (95% confidence interval = 3-44%) increase was related to an interquartile range increase (26.2 µg/m3) on the same day and a 19% (95% confidence interval = 0-40%) increase on the second day. A two-pollutant model was applied, and the results indicated that the effect of PM2.5 was significantly associated with the occurrence of Afib. Patients aged over 65 years with DM and with hyperlipidemia were more susceptible to the effect of PM2.5. CONCLUSIONS: In conclusion, the occurrence of Afib was associated with short-term exposure to fine particulate air pollutants in the general population.

Effects of night duty events on blood pressure and autonomic modulation in physicians.

BACKGROUND: The dynamic effects of duty events on the blood pressure (BP) and heart rate variability (HRV) of physicians on duty are unknown. METHODS: A study was conducted among 12 physicians on night duty. BP and HRV with and without the effect of a duty event were compared. The risk of higher BP and impaired HRV after a phone call were calculated. RESULTS: Physicians had higher mean BP (122.4 ± 11.1; 76.9 ± 7.1 mmHg) within 30 min after a phone calls than without a phone call (113.5 ± 5.3; 69.0 ± 3.8) and higher sympathetic tone (low frequency normalized units (LFnu) 68.5 ± 8.9; high frequency normalized units (HFnu) 27.7 ± 8.7) within 10 min of a phone call than without a phone call (62.9 ± 8.51; 33.5 ± 8.4). Elevated BP and sympathetic tone recovered to baseline levels 30 min after a phone call. CONCLUSIONS: Among physicians on night duty, sympathetic tone and BP might be elevated by clinical events, and these effects last for 30 min.

Cryptotanshinone Inhibits STAT3 Signaling to Alleviate Cardiac Fibrosis in Type 1-like Diabetic Rats.

Cryptotanshinone is an active principal ingredient isolated from Salvia miltiorrhiza (Danshen), a medicinal plant used in China to treat cardiac disorders. The objective of this study was to investigate the effect of cryptotanshinone on myocardial fibrosis in diabetic rats. In streptozotocin-induced type 1 diabetic model hyperglycemic rats (STZ-treated rats), fasting blood glucose levels and heart weight/body weight ratio were markedly increased but both were not modified by cryptotanshinone. Additionally, cardiac performance in catheterized STZ-treated rats was improved. The histological results from Masson staining showed that cryptotanshinone attenuated cardiac fibrosis in STZ-treated rats. Moreover, both the mRNA and protein levels of the signal transducer and activator of transcription 3 (STAT3), matrix metalloproteinase-9, and connective tissue growth factor were reduced by cryptotanshinone in high glucose-cultured cardiomyocytes, similar to the reductions observed in the hearts of STZ-treated rats. In conclusion, while STAT3 regulates matrix metalloproteinase-9 and connective tissue growth factor expression in diabetic rats with cardiac fibrosis, cryptotanshinone inhibited fibrosis to improve cardiac function by suppressing the STAT3 pathway. Cryptotanshinone is suitable as an alternative remedy for therapy of cardiac fibrosis. Copyright © 2017 John Wiley & Sons, Ltd.

Ginsenoside Rh2 Improves Cardiac Fibrosis via PPARδ-STAT3 Signaling in Type 1-Like Diabetic Rats.

Ginsenoside Rh2 (Rh2) is an active principal ingredient contained in ginseng (Panax ginseng Meyer), a medicinal herb used to enhance health worldwide. The present study is designed to investigate the effect of Rh2 on myocardial fibrosis in diabetic rats. In a streptozotocin-induced model of type-1 diabetic rats (STZ-diabetic rats), the increased fasting blood glucose levels and heart weight/body weight (HW/BW) ratio were substantially alleviated by Rh2. Moreover, Rh2 improved cardiac performance in STZ-diabetic rats. Histological results from Masson staining showed that Rh2 attenuated cardiac fibrosis in STZ-diabetic rats. The effects of Rh2 were reversed by GSK0660 at a dose sufficient to inhibit peroxisome proliferator-activated receptor δ (PPARδ) in STZ-diabetic rats. The role of PPARδ was subsequently investigated in vitro. Rh2 restored the decreased PPARδ expression level in high glucose-cultured cardiomyocytes. Moreover, increased protein levels of fibrotic signals, including signal transducer and activator of transcription 3 (STAT3), connective tissue growth factor (CCN2) and fibronectin, were reduced by Rh2 in high glucose-cultured cardiomyocytes. These effects of Rh2 were reversed by GSK0660 or siRNA specific for PPARδ Taken together, PPARδ activation may inhibit STAT3 activation to reduce CCN2 and fibronectin expression in diabetic rats with cardiac fibrosis. Moreover, Rh2 improves cardiac function and fibrosis by increasing PPARδ signaling. Therefore, Rh2 is suitable to develop as an alternative remedy for cardiac fibrosis.

Insomnia and the Risk of Atrial Fibrillation: A Population-Based Cohort Study.

BACKGROUND: Although advancements in the treatment of atrial fibrillation have improved patient prognosis for this persistent condition, interest in atrial fibrillation development is growing. Of note is the fact that additional attention is being focused on the accompanying effect of insomnia. The aim of the study was to investigate the effects of insomnia on the risk of atrial fibrillation development. METHODS: This was a nationwide population-based retrospective cohort study using data from the Taiwan National health Insurance Research Database. We analyzed 64,421 insomnia cases and 128,842 matched controls without insomnia from January 1, 2000, to December 31, 2010. A Cox regression model was used to estimate the adjusted hazard ratios (HRs) and 95% confidence intervals (CI) for atrial fibrillation development. RESULTS: During the follow-up period, the incidence of atrial fibrillation development was significantly higher in the insomnia cases than in the comparison cohort (2.6% vs. 2.3%, p < 0.001). Insomnia was associated with an increased risk of atrial fibrillation (HR = 1.08, 95% CI: 1.01-1.14). Males, those > 65 years of age, and patients with peripheral artery disease who have insomnia had a higher rate of atrial fibrillation development. CONCLUSIONS: The findings of this nationwide analysis support the hypothesis that insomnia is associated with a significant risk of atrial fibrillation development.

Increased night duty loading of physicians caused elevated blood pressure and sympathetic tones in a dose-dependent manner.

PURPOSE: Night duty has been recognized as a significantly harmful stressor for physicians. However, the relationship between various levels of duty loading and stress response is unknown. This study examined whether duty load increases cardiovascular stress indicators in a dose-dependent manner. METHODS: An unallocated prospective observational study was conducted among physicians performing various levels of duties in a secondary referral medical center between 2011 and 2012. Heart rate variability (HRV), blood pressure (BP), and other stress markers of 12 attending physicians were compared during different duty loads: non-duty day (NDD), duty day with one duty area and three wards (1DD), and duty day with two duty areas and six wards (2DD). RESULTS: During the regular sleep time (i.e., 11 p.m. to 5 a.m.), the relative sympathetic modulations measured using the HRV were 59.0 ± 9.3, 61.6 ± 10.4, and 64.4 ± 8.9 for NDD, 1DD, and 2DD, respectively (p = 0.0012); those for relative parasympathetic modulations were 37.4 ± 9.4, 34.8 ± 9.8, and 32.0 ± 8.8 for NDD, 1DD, and 2DD, respectively (p = 0.0015). The percentages of abnormal systolic BPs were 9.7 ± 13.2 %, 25.3 ± 21.8 %, and 31.5 ± 21.0 % for NDD, 1DD, and 2DD, respectively (p = 0.003), and the percentages of abnormal diastolic BP were 6.7 ± 11.0 %, 18.3 ± 11.1 %, and 27.1 ± 30.9 % for NDD, 1DD, and 2DD, respectively (p = 0.002). Total sleep time was negatively associated with sympathetic/parasympathetic balance and the percentage of abnormal diastolic BP. Admitting new patients was positively associated with the percentages of abnormal systolic BP. CONCLUSIONS: This observational analysis suggests that the dose-dependent stress responses of the cardiovascular system in physicians were caused by the duty load.

Activation of ß-adrenoceptors by dobutamine may induce a higher expression of peroxisome proliferator-activated receptors δ (PPARδ) in neonatal rat cardiomyocytes.

Recent evidence showed the role of peroxisome proliferator-activated receptors (PPARs) in cardiac function. Cardiac contraction induced by various agents is critical in restoring the activity of peroxisome proliferator-activated receptors δ (PPARδ) in cardiac myopathy. Because dobutamine is an agent widely used to treat heart failure in emergency setting, this study is aimed to investigate the change of PPARδ in response to dobutamine. Neonatal rat cardiomyocytes were used to examine the effects of dobutamine on PPARδ expression levels and cardiac troponin I (cTnI) phosphorylation via Western blotting analysis. We show that treatment with dobutamine increased PPARδ expression and cTnI phosphorylation in a time- and dose-dependent manner in neonatal rat cardiomyocytes. These increases were blocked by the antagonist of ß1-adrenoceptors. Also, the action of dobutamine was related to the increase of calcium ions and diminished by chelating intracellular calcium. Additionally, dobutamine-induced action was reduced by the inhibition of downstream messengers involved in this calcium-related pathway. Moreover, deletion of PPARδ using siRNA generated the reduction of cTnI phosphorylation in cardiomyocytes treated with dobutamine. Thus, we concluded that PPARδ is increased by dobutamine in cardiac cells.

Improvement of insulin resistance by Chlorella in fructose-rich chow-fed rats.

Chlorella is a type of unicellular fresh water algae. In an attempt to develop new agents for handling insulin resistance, Chlorella was employed to screen the effect on insulin resistance in rats induced by fructose-rich chow. A single oral administration of Chlorella for 90 min decreased the plasma glucose in a dose-dependent manner in rats receiving 4-week fructose-rich chow. In addition, chronic treatment with Chlorella for 15 days also lowered plasma glucose in the same manner. Then, the insulin action on glucose disposal rate was measured using the glucose-insulin index, values of the areas under the curves of glucose and insulin during the intraperitoneal glucose tolerance test (IPGTT). Oral administration (three times daily for 5 days) of Chlorella to rats receiving 4 weeks of fructose-rich chow abolished the elevated value of the glucose-insulin index, indicating that Chlorella has an ability to improve insulin resistance. An increase of insulin sensitivity by Chlorella was further evaluated using the plasma glucose lowering action of exogenous insulin in streptozotocin-induced diabetic rats (STZ-diabetic rats). Oral administration of Chlorella three times daily to STZ-diabetic rats increased the response to exogenous insulin 15 days later. The obtained results suggest that oral administration of Chlorella has the ability to improve insulin sensitivity, which may be used as an adjuvant therapy for patients with insulin resistance.

Effects of metformin on rosiglitazone-induced cardiac hypertrophy in mice.

Thiazolidinediones (TZD) can cause adipose tissue accumulation and myocardial hypertrophy. This study aimed to determine if combined Metformin (Glucophage) and Rosiglitazone (Avandia) could reduce the risk of heart failure caused by Rosiglitazone in BALB/c mice. BALB/c mice were treated with oral Rosiglitazone/Metformin twice daily for four weeks. Metformin or Rosiglitazone alone and non-treated mice acted as double control. Myocardial hypertrophy and associated side effects of the combined therapy were determined through isolated heart and body weights. Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were applied to evaluate expression of sulfonylurea receptor 2A (SUR2A) and Kir 6.2. The activities of peroxisome proliferator activated receptor alpha (PPARalpha) in the myocardium were also observed. Rosiglitazone/Metformin decreased body weight gain and food intake, and inhibited an increasing adipose ratio but did not reduce myocardial hypertrophy. Rosiglitazone increased Kir6.2/SUR2A, Kir6.2/SUR2B, and PPARalpha gene expression. The Rosiglitazone/Metformin combination further increased these gene expressions, especially PPARalpha. Metformin inhibits obesity but has no effect in reducing myocardial hypertrophy caused by Rosiglitazone. Whether Metformin can reduce side effects of TZDs in humans warrants further study.

Dynamic blood pressure changes and recovery under different work shifts in young women.

BACKGROUND: Some studies have reported that shift work can affect blood pressure (BP), but few have studied recovery from BP changes occurring during different shifts. METHODS: We recruited 16 young female nurses working rotating shifts and six working the regular day shift. All received repeated ambulatory BP monitoring (ABPM) during their workdays and following day off. RESULTS: Our linear mixed-effect model showed that both systolic and diastolic BPs were significantly decreased during sleeping period and significantly increased while on working period, on a work day, but increased during sleeping period after a night shift or evening shift. BP measurements that changed after evening shift usually returned to baseline on consecutive off-duty day after day shift, but they did not completely return to baseline after a night shift (P < 0.05). We also found 69% of those working rotating shifts had at least changed once in dipper/nondipper status. The rates of change in dipper/nondipper status between work day and off-duty day were 33, 44, 50, and 38% for nurses worked in outpatient clinic, night shift, evening shift, and day shift, respectively. CONCLUSION: Shift work is significantly associated with BP and possibly dipper/nondipper status in young female nurses. Except for those working night shifts, BP levels returned to baseline the off-duty day after day shift. We recommend that potential influence of shift work be considered when evaluating a person's BP.

Investigation of triamterene as an inhibitor of the TGR5 receptor: identification in cells and animals.

BACKGROUND: G-protein-coupled bile acid receptor 1 (GPBAR1, also known as TGR5) has been shown to participate in glucose homeostasis. In animal models, a TGR5 agonist increases incretin secretion to reduce hyperglycemia. Many agonists have been developed for clinical use. However, the effects of TGR5 blockade have not been studied extensively, with the exception of studies using TGR5 knockout mice. Therefore, we investigated the potential effect of triamterene on TGR5. METHODS: We transfected the TGR5 gene into cultured Chinese hamster ovary cells (CHO-K1 cells) to express TGR5. Then, we applied a fluorescent indicator to examine the glucose uptake of these transfected cells. In addition, NCI-H716 cells that secrete incretin were also evaluated. Fura-2, a fluorescence indicator, was applied to determine the changes in calcium concentrations. The levels of cyclic adenosine monophosphate (cAMP) and glucagon-like peptide (GLP-1) were estimated using enzyme-linked immunosorbent assay kits. Moreover, rats with streptozotocin (STZ)-induced type 1-like diabetes were used to investigate the effects in vivo. RESULTS: Triamterene dose dependently inhibits the increase in glucose uptake induced by TGR5 agonists in CHO-K1 cells expressing the TGR5 gene. In cultured NCI-H716 cells, TGR5 activation also increases GLP-1 secretion by increasing calcium levels. Triamterene inhibits the increased calcium levels by TGR5 activation through competitive antagonism. Moreover, the GLP-1 secretion and increased cAMP levels induced by TGR5 activation are both dose dependently reduced by triamterene. However, treatment with KB-R7943 at a dose sufficient to block the Na+/Ca2+ exchanger (NCX) failed to modify the responses to TGR5 activation in NCI-H716 cells or CHO-K1 cells expressing TGR5. Therefore, the inhibitory effects of triamterene on TGR5 activation do not appear to be related to NCX inhibition. Blockade of TGR5 activation by triamterene was further characterized in vivo using the STZ-induced diabetic rats. CONCLUSION: Based on the obtained data, we identified triamterene as a reliable inhibitor of TGR5. Therefore, triamterene can be developed as a clinical inhibitor of TGR5 activation in future studies.

Loperamide-induced Cardiac Depression Is Enhanced by Hyperglycemia: Evidence Relevant to Loperamide Abuse.

BACKGROUND AND AIMS: Cardiac dysryhthmias and death are reported after loperamide abuse. The mechanism of death is not clear and cardiac depression may play a role in this mechanism. Loperamide is widely used as an agonist of the µ-opioid receptor (MOR) in clinical practice. In skeletal muscle, an increase in MOR in response to hyperglycemia is largely attributable to higher expression of the transducer and activator of transcription 3 (STAT3), which binds to the promoter of the MOR genes. Therefore, we investigated the changes in cardiac MOR caused by hyperglycemia both in vivo and in vitro. METHODS: Streptozotocin-induced type 1-like diabetic rats (STZ rats) were used to estimate cardiac performance and changes in cardiac MOR under the influence of loperamide. STAT3 was measured in cultured cardiomyocytes under high glucose (HG) to mimic the in vivo changes. RESULTS: Loperamide-induced reduction of cardiac performance was more marked in STZ rats than in normal rats. The increased MOR in the hearts of STZ rats was reversed by the reduction of hyperglycemia. Higher MOR expression paralleled the increase in STAT3 in cardiomyocytes under HG and was reversed by siRNA of STAT3. Stattic at a dose sufficient to inhibit STAT3 reduced MOR both in vivo and in vitro. CONCLUSION: Cardiac depression induced by loperamide is enhanced by hyperglycemia due to higher MOR expression, which is associated with higher expression of STAT3 in the heart. These results suggest that loperamide abuse is particularly dangerous for individuals with hyperglycemia.

Ursolic acid activates the TGR5 receptor to enhance GLP-1 secretion in type 1-like diabetic rats.

Endogenous Takeda G-protein-coupled receptor 5 (TGR5), G-protein-coupled bile acid receptor 1 (GPBAR1), regulates glucose metabolism. In animals, TGR5 activation by a chemical agonist may increase incretin secretion and reduce the blood sugar level. Recently, betulinic acid has been suggested to activate TGR5. Ursolic acid is a well-known pentacyclic triterpenoid that is similar to betulinic acid. It is of special interest to determine the potential effect of ursolic acid on TGR5. Therefore, we transfected cultured Chinese hamster ovary (CHO-K1) cells with the TGR5 gene. The functions of the transfected cells were confirmed via glucose uptake using a fluorescent indicator. Moreover, NCI-H716 cells that secreted incretin were also investigated, and the glucagon-like peptide (GLP-1) levels were quantified using ELISA kits. In addition, streptozotocin (STZ)-induced type 1-like diabetic rats were used to identify the effect of ursolic acid in vivo. Ursolic acid concentration dependently increased glucose uptake in CHO-K1 cells expressing TGR5. In NCI-H716 cells, ursolic acid induced a concentration-dependent elevation in GLP-1 secretion, which was inhibited by triamterene at the effective concentrations to block TGR5. Ursolic acid also increased the plasma GLP-1 level via TGR5 activation, which was further characterized in vivo with type 1-like diabetic rats. Moreover, ursolic acid is more effective than betulinic acid in reduction of hyperglycemia and increase of GLP-1 secretion. Therefore, we demonstrated that ursolic acid can activate TGR5, enhancing GLP-1 secretion in vitro and in vivo. Therefore, ursolic acid is suitable for use in TGR5 activation.

Grand rounds: outbreak of hematologic abnormalities in a community of people exposed to leakage of fire extinguisher gas.

CONTEXT: Although there are ample data on the respiratory effects of exposure to fire extinguisher gas, the potential hematologic effects have not been fully documented. We conducted this study to determine the possible etiologic agent(s) for a decrease in red blood cells among community residents in Taipei, Taiwan, after they were exposed to leakage of mixed fire extinguishants containing bromotrifluoromethane (CF3Br, Halon 1301), bromochlorodifluoromethane (CF2BrCl, Halon 1211), and dichlorodifluoromethane (CCl2F2, CFC-12). CASE PRESENTATION: We studied 117 exposed residents who came into one hospital for physical examinations. We also selected age- and sex-matched referents for comparison from residents who came to the same hospital for health examinations. Nine months after the exposure to mixed fire extinguishants, 91 of the exposed residents came back for a second physical examination. In the first examination of the exposed residents, we found a significant reduction in red blood cell count and hemoglobin and a relationship between dose and response. DISCUSSION: After excluding iron-deficiency anemia, thalassemia, and other possible agents, we suspected that the hematologic effects might have resulted from pyrolytic products of CFC-12 and Halon 1211, which may contain phosgene, among other products. RELEVANCE TO CLINICAL PRACTICE: The acute transient hematologic effects observed in the exposed residents were associated with the incident of leakage of mixed fire-extinguisher gases and were most likely caused by a small amount of pyrolytic products, probably phosgene. Nine months after the exposure, we found a significant improvement in the abnormalities without any specific treatment.

Development of betulinic acid as an agonist of TGR5 receptor using a new in vitro assay.

BACKGROUND: G-protein-coupled bile acid receptor 1, also known as TGR5 is known to be involved in glucose homeostasis. In animal models, treatment with a TGR5 agonist induces incretin secretion to reduce hyperglycemia. Betulinic acid, a triterpenoid present in the leaves of white birch, has been introduced as a selective TGR5 agonist. However, direct activation of TGR5 by betulinic acid has not yet been reported. METHODS: Transfection of TGR5 into cultured Chinese hamster ovary (CHO-K1) cells was performed to establish the presence of TGR5. Additionally, TGR5-specific small interfering RNA was employed to silence TGR5 in cells (NCI-H716 cells) that secreted incretins. Uptake of glucose by CHO-K1 cells was evaluated using a fluorescent indicator. Amounts of cyclic adenosine monophosphate and glucagon-like peptide were quantified using enzyme-linked immunosorbent assay kits. RESULTS: Betulinic acid dose-dependently increases glucose uptake by CHO-K1 cells transfected with TGR5 only, which can be considered an alternative method instead of radioligand binding assay. Additionally, signals coupled to TGR5 activation are also increased by betulinic acid in cells transfected with TGR5. In NCI-H716 cells, which endogenously express TGR5, betulinic acid induces glucagon-like peptide secretion via increasing calcium levels. However, the actions of betulinic acid were markedly reduced in NCI-H716 cells that received TGR5-silencing treatment. Therefore, the present study demonstrates the activation of TGR5 by betulinic acid for the first time. CONCLUSION: Similar to the positive control lithocholic acid, which is the established agonist of TGR5, betulinic acid has been characterized as a useful agonist of TGR5 and can be used to activate TGR5 in the future.

Increase of PPARδ by dopamine mediated via DA-1 receptor-linked phospholipase C pathway in neonatal rat cardiomyocytes.

BACKGROUND: Role of peroxisome proliferator-activated receptor δ (PPARδ) in cardiac contraction has recently been established. Dopamine is one of the agents used to treat heart failure in clinics. But the mediation of PPARδ in cardiac action of dopamine is still unclear. METHODS: The present study is aimed to clarify this point using neonatal rat cardiomyocytes to investigate the changes of PPARδ expression and cardiac troponin I (cTnI) phosphorylation by Western blotting analysis. Antagonists of receptors, inhibitor of phospholipase C (PLC) (U73122), calcium chelator (BAPTA-AM), and inhibitor of protein kinase A (PKAI) were also applied. We silenced PPARδ by RNAi to identify the major role of PPARδ in dopamine-induced actions. RESULTS: Dopamine increases PPARδ expression and cardiac troponin I (cTnI) phosphorylation in a time- and dose-dependent manner in neonatal rat cardiomyocytes. Moreover, both actions of dopamine were blocked by DA1 receptor antagonist and PLC inhibitor but not by PKAI. The increase of cTnI phosphorylation by dopamine was also inhibited in cardiomyocytes silenced by RNAi of PPARδ. CONCLUSION: We suggest that dopamine can enhance cardiac contraction mainly through an activation of DA1 receptor-linked PLC pathway to increase cellular calcium ions for the increase of PPARδ expression.

Working the night shift causes increased vascular stress and delayed recovery in young women.

Shiftwork has been associated with elevated blood pressure (BP) and decreased heart-rate variability (HRV), factors that may increase the long-term risk of cardiovascular-related mortality and morbidity. This study explored the effect of shiftwork on dynamic changes in autonomic control of HRV (cardiac stress), systolic BP and diastolic BP, i.e., SBP and DBP (vascular stress), and recovery in the same subjects working different shifts. By studying the same subjects, the authors could reduce the effect of possible contribution of between-subject variation from genetic predisposition and environmental factors. The authors recruited 16 young female nurses working rotating shifts--day (08:00-16:00 h), evening (16:00-00:00 h), and night (00:00-08:00 h)--and 6 others working the regular day shift. Each nurse received simultaneous and repeated 48-h ambulatory electrocardiography and BP monitoring during their work day and the following off-duty day. Using a linear mixed-effect model to adjust for day shift, the results of the repeated-measurements and self-comparisons found significant shift differences in vascular stress. While working the night shift, the nurses showed significant increases in vascular stress, with increased SBP of 9.7 mm Hg. The changes of SBP and DBP seemed to peak during waking time at the same time on the day off as they did on the working day. Whereas HRV profiles usually returned to baseline level after each shift, the SBP and DBP of night-shift workers did not completely return to baseline levels the following off-duty day (p < .001). The authors concluded that although the nurses may recover from cardiac stress the first day off following a night shift, they do not completely recover from increases in vascular stress on that day.