Circadian rhythms of hemostatic factors in tetraplegia: a double-blind, randomized, placebo-controlled cross-over study of melatonin

Circadian misalignment disrupts biomarkers of cardiovascular disease risk and promotes a hypercoagulable state

The circadian system regulates 24-h time-of-day patterns of cardiovascular physiology, with circadian misalignment resulting in adverse cardiovascular risk. Although many proteins in the coagulation-fibrinolysis axis show 24-h time-of-day patterns, it is not understood if these temporal patterns are regulated by circadian or behavioral (e.g., sleep and food intake) cycles, or how circadian misalignment influences these patterns. Thus, we utilized a night shiftwork protocol to analyze circadian versus behavioral cycle regulation of 238 plasma proteins linked to cardiovascular physiology. Six healthy men aged 26.2 ± 5.6 years (mean ± SD) completed the protocol involving two baseline days with 8-h nighttime sleep opportunities (circadian alignment), a transition to shiftwork day, followed by 2 days of simulated night shiftwork with 8-h daytime sleep opportunities (circadian misalignment). Plasma was collected for proteomics every 4 h across 24 h during baseline and during daytime sleep and the second night shift. Cosinor analyses identified proteins with circadian or behavioral cycle-regulated 24-h time-of-day patterns. Five proteins were circadian regulated (plasminogen activator inhibitor-1, angiopoietin-2, insulin-like growth factor binding protein-4, follistatin-related protein-3, and endoplasmic reticulum resident protein-29). No cardiovascular-related proteins showed regulation by behavioral cycles. Within the coagulation pathway, circadian misalignment decreased tissue factor pathway inhibitor, increased tissue factor, and induced a 24-h time-of-day pattern in coagulation factor VII (all FDR < 0.10). Such changes in protein abundance are consistent with changes observed in hypercoagulable states. Our analyses identify circadian regulation of proteins involved in cardiovascular physiology and indicate that acute circadian misalignment could promote a hypercoagulable state, possibly contributing to elevated cardiovascular disease risk among shift workers.

Circadian rhythms of risk factors and management in atherosclerotic and hypertensive vascular disease: Modern chronobiological perspectives of an ancient disease

Atherosclerosis, a chronic inflammatory disease of the arteries that appears to have been as prevalent in ancient as in modern civilizations, is predisposing to life-threatening and life-ending cardiac and vascular complications, such as myocardial and cerebral infarctions. The pathogenesis of atherosclerosis involves intima plaque buildup caused by vascular endothelial dysfunction, cholesterol deposition, smooth muscle proliferation, inflammatory cell infiltration and connective tissue accumulation. Hypertension is an independent and controllable risk factor for atherosclerotic cardiovascular disease (CVD). Conversely, atherosclerosis hardens the arterial wall and raises arterial blood pressure. Many CVD patients experience both atherosclerosis and hypertension and are prescribed medications to concurrently mitigate the two disease conditions. A substantial number of publications document that many pathophysiological changes caused by atherosclerosis and hypertension occur in a manner dependent upon circadian clocks or clock gene products. This article reviews progress in the research of circadian regulation of vascular cell function, inflammation, hemostasis and atherothrombosis. In particular, it delineates the relationship of circadian organization with signal transduction and activation of the renin-angiotensin-aldosterone system as well as disturbance of the sleep/wake circadian rhythm, as exemplified by shift work, metabolic syndromes and obstructive sleep apnea (OSA), as promoters and mechanisms of atherogenesis and risk for non-fatal and fatal CVD outcomes. This article additionally updates advances in the clinical management of key biological processes of atherosclerosis to optimally achieve suppression of atherogenesis through chronotherapeutic control of atherogenic/hypertensive pathological sequelae.

A review of sleep research in patients with spinal cord injury

Study design: Systematic review. Objectives: Sleep disturbances are a common complaint among individuals with spinal cord injury (SCI) and were not usually present before the SCI. Their sleep disturbances, including disrupted sleep, spasms, and problems with initiating and sustaining sleep through the night, affect SCI individuals' overall quality of life due to excessive tiredness and low energy levels during the day. Despite the high prevalence of sleep complaints in this population, current knowledge about sleep in the SCI population has not been systematically assessed. Setting: Capital Region of Denmark. Methods: We systematically reviewed literature identified from the PubMed and EMBASE databases following PRISMA guidelines.Thirty-seven articles met our inclusion criteria, as only controlled studies were included. This could be a comparison of (1) SCI individuals and able-bodied controls, (2) cervical with thoracolumbar SCI individuals, or (3) cervical, thoracolumbar SCI individuals and able-bodied controls. Results: Individuals with SCI have a higher prevalence of sleep-disordered breathing and periodic leg movements during sleep (PLMS), lower heart rate, but no nocturnal lowering of blood pressure. 24-hour energy expenditure and sleeping metabolic rate were significantly lower, and bowel movements were altered. Endocrine alterations were found in investigations of melatonin, cortisol and antidiuretic hormone. Questionnaires revealed a high prevalence of subjectively poorer sleep quality in individuals with SCI compared with able-bodied controls. Conclusions: There are significant differences between groups with SCI and able-bodied controls. SCI objectively and subjectively markedly affects an individual's sleep.

Systematic review of melatonin levels in individuals with complete cervical spinal cord injury

Context: Pineal melatonin production is mediated by afferent signaling pathways that navigate through the cervicothoracic spinal cord. Melatonin profiles in individuals with complete cervical spinal cord injury (SCI) have not been systematically reviewed despite this proposed pathway. Objectives: The primary objective was to understand melatonin profiles in individuals with complete cervical SCI, as compared to healthy controls and those with thoracolumbar and incomplete cervical SCI. Secondary objectives were to understand the impact of injury chronicity and melatonin supplementation on melatonin values in adults with complete cervical SCI. Methods: This review (PROSPERO ID: CRD42017073767) searched several databases and gray literature sources from January 1978 to August 2017. Studies were eligible if they evaluated melatonin levels (blood, saliva or urinary metabolite measurements) in adults with complete cervical SCI. 390 studies were screened and 12 studies met final selection criteria. Given the heterogeneity in study designs, a narrative analysis was performed. Results: There is evidence that adults with complete cervical SCI have absent diurnal melatonin rhythms as compared to healthy controls and individuals with thoracolumbar SCI below T3. There is limited evidence comparing levels in individuals with incomplete tetraplegia. There is insufficient evidence describing profiles immediately (<2 weeks) after cervical SCI. Based on a limited number of studies, melatonin supplementation does not appear to improve sleep outcomes in adults with long-standing complete cervical SCI. Conclusions: Future research should explore melatonin levels acutely after cervical SCI and the impact of supplementation on non-sleep outcomes.

Impact Of Spinal Cord Injury On Sleep: Current Perspectives

Sleep disorders are commonly encountered in people living with spinal cord injury (SCI). Primary sleep disorders such as sleep-disordered breathing (SDB), sleep-related movement disorders, circadian rhythm sleep-wake disorders, and insomnia disorder are common conditions after SCI but remain under-recognized, underdiagnosed and therefore remain untreated for a majority of patients. Sleep disturbances in people living with SCI are associated with significant impairments of daytime function and quality of life. Previous reviews have described findings related mainly to SDB but have not examined the relationship between other sleep disorders and SCI. This narrative review examines various sleep abnormalities and related functional and physical impairments in people living with SCI. It discusses new evidence pertaining to management, highlights existing limitations in the literature and recommends future directions for research.

Melatonin and cortisol in individuals with spinal cord injury

STUDY OBJECTIVES

The aim of this study was to investigate circadian rhythm and sleep complaints in individuals with spinal cord injury (SCI) as determined by diurnal saliva melatonin and cortisol as well as activity measurements and subjective sleep quality.

METHODS

Fourteen patients with cervical SCI (cSCI), six patients with thoracic SCI (tSCI) and eight able-bodied controls all underwent two consecutive weeks wearing a wrist actigraph in addition to filling out a sleep diary. During one 24-h period, cortisol and melatonin were measured at 4-h intervals. Furthermore, participants' sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and their overall daytime sleepiness was assessed using the Epworth Sleepiness Scale (ESS).

RESULTS

The cSCI group demonstrated lower melatonin levels compared with the tSCI group and the controls at the 24:00 and 04:00 time points. Moreover, at one time point the tSCI group had a higher cortisol level than the cSCI group and the controls. In addition, baseline systolic blood pressure and oxygen saturation were significantly lower in the cSCI group. No differences were found in activity measurements or self-reported sleep quality.

CONCLUSIONS

Individuals with cSCI demonstrate reduced melatonin secretion compared with tSCI individuals, but not in other circadian measures. This supports an involvement of melatonergic cervical fibers associated with the cervical lesion.

Effectiveness of dietary supplements in spinal cord injury subjects

BACKGROUND

Individuals with spinal cord injury (SCI) consume more dietary supplements than the general population. However, there is limited information regarding the clinical effectiveness of dietary supplements in SCI population.

OBJECTIVE

To systematically review the effectiveness of dietary supplements for the prevention or treatment of health-related conditions associated with SCI.

METHODS

Randomized or non-randomized controlled clinical trials were selected, comparing the effect of any dose and form of a dietary supplement (defined by the Dietary Supplement Health and Education Act), with either no treatment, placebo, or other medication. Data Sources included the Cochrane Database, DARE, LILACS, CINAHL, EMBASE, MEDLINE, OTSeeker, PEDro, PsycINFO, SpeechBITE, ScienceDirect, Scopus, clinicaltrials.gov, Google Scholar, and OpenGrey. Two reviewers independently classified articles from January 1970 through October 2015, and 18 articles were selected.

RESULTS

Due to the heterogeneity of outcome measures across studies, a meta-analysis was not conducted. However, high-quality evidence showed that cranberry supplementation is not effective for prevention of urinary tract infections (UTIs) in SCI. Moderate-quality evidence supported a beneficial effect of vitamin D, alpha-lipoic acid, and omega-3 supplementation, although replication of results is needed. There were conflicting results for the effect of creatine supplementation on improvement of motor outcomes. Low-quality evidence does not permit assessment of the effectiveness of melatonin, whey protein, vitamin C, and Chinese herb in SCI.

CONCLUSIONS

There is sufficient data suggesting that cranberry supplementation is ineffective for prevention of UTIs in individuals with SCI. There is insufficient data to support or refute the use of any other dietary supplement in individuals with SCI.

Reduced peak, but no diurnal variation, in thrombin generation upon melatonin supplementation in tetraplegia. A randomised, placebo-controlled study

Tetraplegic patients have increased risk of venous thrombosis despite anti-thrombotic prophylaxis. Moreover, they have blunted plasma variations in melatonin and altered diurnal variation of several haemostatic markers, compared with able-bodied. However, whether healthy individuals and tetraplegic patients, with or without melatonin, display abnormalities in thrombin generation during a 24-hour (h) cycle, is unknown. We therefore used the Calibrated Automated Thrombogram (CAT) assay to examine diurnal variations and the possible role of melatonin in thrombin generation. Six men with long-standing complete tetraplegia were included in a randomised placebo-controlled cross-over study with melatonin supplementation (2 mg, 4 consecutive nights), whereas six healthy, able-bodied men served as controls. Ten plasma samples were collected frequently during a 24-h awake/sleep cycle. No significant diurnal variation of any of the measured CAT indices was detected in the three study groups. Whereas endogenous thrombin potential (ETP) was independent (p > 0.05) of whether the tetraplegic men received melatonin or placebo, melatonin decreased (p = 0.005) peak values in tetraplegia compared with those given placebo. Able-bodied men had lower (p = 0.019) ETP and Lag-Time (p = 0.018) compared with tetraplegics receiving placebo. Neither the Time-to-Peak nor the Start-Tail was affected (p > 0.05) by melatonin in tetraplegia. In conclusion, indices of thrombin generation are not subjected to diurnal variation in healthy able-bodied or tetraplegia, but peak thrombin generation is reduced in tetraplegic men receiving oral melatonin.