Endothelin-1's chronome indicates diabetic and vascular disease chronorisk

Metabolic interactions between hyperhomocysteinemia and endothelin-1 among Tunisian patients with acute coronary diseases

BACKGROUND

Acute coronary syndromes (ACS) are complex and polygenic diseases which are a real problem of public health. These syndromes require multidisciplinary studies to understand the pathogenesis mechanisms and metabolic interactions between different risk factors.This study aimed to explore the variation of two coronary risk parameters not mentioned by Framingham cohorts, hyperhomocysteinemia and endothelin-1 (ET-1) in Tunisian coronary and the study of the variation of these parameters based on various cardiac risk factors and metabolic relationship between them.To 157 coronary and 142 healthy subjects, the concentration of homocysteine was quantified by fluorescence polarization immunoassay; the concentration of ET-1 was measured by an analytical technique, the High Performance Liquid Chromatography (HPLC) coupled with mass spectrometry.

RESULTS

Our study showed that homocysteine and ET-1 were significantly higher in patients compared to healthy subjects (24.40 ± 12.5 μmol/L vs 7.44 ± 2.5 μmol/L p <0.00001) for homocysteine and (15.2 ± 5.3 nmol/L vs 7.1 ± 2.7 nmol/L, p <0.00001) for ET-1. On the other hand, homocysteine varies according to tobacco and diabetes while ET-1 depends on the sex, hypertension, smoking, obesity and dyslipidemia and a statistically negative correlation was shown between homocysteine and ET-1 in coronary patients (r = -0.66 p <0.00001).

CONCLUSION

The study of the variation of these two parameters in coronary patients and metabolic exploration of the relationship between homocysteine and ET-1 according to various risk factors and the interactions between themselves facilitates the decision of therapeutic treatment.

Endothelin-1 and psychosocial risk factors for cardiovascular disease: a systematic review

OBJECTIVES

Psychosocial factors (i.e., social environment and emotional factors) contribute to an increased risk of cardiovascular disease (CVD). Perturbation in a potent vasoconstrictive peptide endothelin (ET)-1 could be one of the mechanisms linking psychosocial factors to CVD. Our aim was to evaluate the literature on the relationship between plasma ET-1 and psychosocial risk factors for CVD.

METHODS

MEDLINE and PsycINFO databases were searched for articles on human studies published in peer-reviewed English-language journals through September 2012.

RESULTS

Of the 20 studies that met the inclusion criteria, 14 were experimental studies of acute psychological/mental challenges and 6 were observational studies of psychological and social factors. The inferences drawn from this review were as follows: a) laboratory-induced acute psychological/mental stress may result in exaggerated plasma ET-1 release in those with CVD and those at risk for CVD (positive studies: 5/10); b) chronic/episodic psychosocial factors may have a positive relationship to plasma ET-1 (positive studies: 3/5); and c) race (African American), sex (male), and individual differences in autonomic and hemodynamic responses to stress (parasympathetic withdrawal and elevated blood pressure responsiveness) may moderate the relationship between psychosocial factors and plasma ET-1.

CONCLUSIONS

This review indicates that psychosocial risk factors for CVD are associated with elevated plasma ET-1; however, the relatively small number of studies, methodological differences, and variable assessment tools preclude definitive conclusions about the strength of the association. Specific suggestions regarding the selection of psychosocial factors, optimization of acute challenge protocols, and standardization of methods and timing of the ET-1 measures are provided.

Chronic resveratrol treatment restores vascular responsiveness of cerebral arterioles in type 1 diabetic rats

Decreased dilation of cerebral arterioles via an increase in oxidative stress may be a contributing factor in the pathogenesis of diabetes-induced complications leading to cognitive dysfunction and/or stroke. Our goal was to determine whether resveratrol, a polyphenolic compound present in red wine, has a protective effect on cerebral arterioles during type 1 diabetes (T1D). We measured the responses of cerebral arterioles in untreated and resveratrol-treated (10 mg·kg(-1)·day(-1)) nondiabetic and diabetic rats to endothelial (eNOS) and neuronal (nNOS) nitric oxide synthase (NOS)-dependent agonists and to a NOS-independent agonist. In addition, we harvested brain tissue from nondiabetic and diabetic rats to measure levels of superoxide under basal conditions. Furthermore, we used Western blot analysis to determine the protein expression of eNOS, nNOS, SOD-1, and SOD-2 in cerebral arterioles and/or brain tissue from untreated and resveratrol-treated nondiabetic and diabetic rats. We found that T1D impaired eNOS- and nNOS-dependent reactivity of cerebral arterioles but did not alter NOS-independent vasodilation. While resveratrol did not alter responses in nondiabetic rats, resveratrol prevented T1D-induced impairment in eNOS- and nNOS-dependent vasodilation. In addition, superoxide levels were higher in brain tissue from diabetic rats and resveratrol reversed this increase. Furthermore, eNOS and nNOS protein were increased in diabetic rats and resveratrol produced a further increased eNOS and nNOS proteins. SOD-1 and SOD-2 proteins were not altered by T1D, but resveratrol treatment produced a decrease in SOD-2 protein. Our findings suggest that resveratrol restores vascular function and oxidative stress in T1D. We suggest that our findings may implicate an important therapeutic potential for resveratrol in treating T1D-induced cerebrovascular dysfunction.

Inhibition of endothelin-1 receptors improves impaired nitric oxide synthase-dependent dilation of cerebral arterioles in type-1 diabetic rats

OBJECTIVE

Endothelin-1 has been implicated in the pathogenesis of many cardiovascular-related diseases, including diabetes. The goal of this study was to examine the influence of endothelin-1 receptors (ET(A)) in impaired responses of cerebral (pial) arterioles in type-1 diabetic rats.

METHODS

We measured responses of cerebral arterioles in non-diabetic rats to endothelial nitric oxide synthase (eNOS)-dependent (ADP), neuronal nitric oxide synthase (nNOS)-dependent (N-methyl-d-aspartic acid [NMDA]) and NOS-independent (nitroglycerin) agonists before and during application of BQ-123, an ET(A) receptor antagonist. In addition, we harvested brain tissue from non-diabetic and diabetic rats to measure the production of superoxide anion under basal conditions and during inhibition of ET(A) receptors.

RESULTS

We found that diabetes specifically impaired eNOS- and nNOS-dependent reactivity of cerebral arterioles, but did not alter NOS-independent vasodilation. In addition, while BQ-123 did not alter responses in non-diabetic rats, BQ-123 restored impaired eNOS- and nNOS-dependent vasodilation in diabetic rats. Further, superoxide production was higher in brain tissue from diabetic rats compared with non-diabetic rats under basal conditions and BQ-123 decreased basal production of superoxide in diabetic rats.

CONCLUSION

We suggest that activation of ET(A) receptors during type-1 diabetes mellitus plays an important role in impaired eNOS- and nNOS-dependent dilation of cerebral arterioles.

Endothelin-1, big endothelin-1, and nitric oxide in patients with chronic renal disease and hypertension

The complex pathogenesis of chronic renal disease (CRD) depends on endothelin (ET) axis (ETs and ET receptors) and nitric oxide (NO) because of their vasoactive effects and their role in general modulation of vascular homeostasis. Various renal cells synthesize ETs and NO that play a significant role in renal hemodynamics as well as in water and salt excretion via urine. ET-1 is a strong vasoconstrictor. Besides its vasoactive effects, ET-1 modulates mitosis and apoptosis in a cell type-dependent manner, and may play an important role in CRD pathogenesis. The aims of this study were to emphasize the role and interactions of ET-1, Big ET-1, and NO in CRD. Concentrations of these vasoactive molecules were measured in plasma/serum and/or urine of 57 patients with diabetic nephropathy (subgroup 1), arterial hypertension (subgroup 2) or CRD with chronic renal insufficiency (subgroup 3), and in healthy control subjects (n=18). In comparison with control group, urine concentration of Big ET-1 was significantly increased (13.13 pmol/L vs. 11.34 pmol/L; P<0.001) in CRD patients, whereas plasma and urine concentrations of ET-1 did not differ significantly. NO concentrations were also significantly increased in CRD patients (serum, 72.55 micromol/L; P<0.001, and urine 141.74 micromol/L; P<0.05) as compared to control group. Study results indicated that Big ET-1 and NO could be useful diagnostic parameters in CRD for their diagnostic sensitivity and diagnostic specificity (Big ET-1 in urine: 56.1 and 88.9%, and NO in serum: 66.7 and 83.3%, respectively). In addition, Big ET-1 may prove useful in the differential diagnosis of diabetic nephropathy (78.6% diagnostic sensitivity and 88.9% diagnostic specificity).

A chronomic tree of life: ontogenetic and phylogenetic ‘memories’ of primordial cycles — keys to ethics

A scientific optimization may become possible in ethics to the extent to which any reproducible since cyclic features of spirituality and of criminality become measurable. Should either or both the 'good' or the 'bad' be found to be at least passively influenced by cyclic physical environmental factors, as is putatively the case, these aspects of behavior may eventually become actively manipulable, perhaps utilizable for human survival. Toward this goal, chronomics has already mapped time structures in religious behavior that can lead to a study of underlying geographic/geomagnetic latitude-associated mechanisms. This paper, with further but clearly insufficient data, revealing the hurdle of relative brevity of the available time series constitutes a plea for much longer and denser worldwide time series, for further endeavors in various methods of analyses, some of which are promisingly available.

Chronomics: circadian and circaseptan timing of radiotherapy, drugs, calories, perhaps nutriceuticals and beyond

We suggest a putative benefit from timing nutriceuticals (substances that are both nutrients and pharmaceuticals) such as antioxidants for preventive or curative health care, based on the proven merits of timing nutrients, drugs, and other treatments, as documented, i.a., in India. The necessity of timing melatonin, a major antioxidant, is noted. A protocol to extend the scope of chronoradiotherapy awaits testing. Imaging in time by mapping rhythms and broader time structures, chronomes, for earliest diagnoses, for example detection of vascular disease risk, is recommended. The study of rhythms and broader chronomes leads to a dynamic functional genomics, guided by imaging in time of free radicals and antioxidants, amongst many other variables.

Neuropeptide chronomics in clinically healthy young adults: circaoctohoran and circadian patterns

Endothelin-1 (ET-1) undergoes an about 8-h (circaoctohoran) rather than a circadian variation in clinical health. Herein, 24 h plasma concentrations of vasoactive intestinal peptide (VIP), substance P (SP), neuropeptide Y (NpY), and cortisol used as reference, were obtained from 20 healthy young adults starting at 07:00 or 19:00 h. Like ET-1, SP and NpY undergo a circaoctohoran variation, whereas VIP is circadian rhythmic, peaking during the night, some 8 h prior to the circadian acrophase of cortisol. Maps of circadian and extra-circadian patterns may serve for screening, diagnosis and a better understanding of mechanisms underlying the etiology of various diseases.

Transdisciplinary unifying implications of circadian findings in the 1950s

Afew puzzles relating to a small fraction of my endeavors in the 1950s are summarized herein, with answers to a few questions of the Editor-in-Chief, to suggest that the rules of variability in time complement the rules of genetics as a biological variability in space. I advocate to replace truisms such as a relative constancy or homeostasis, that have served bioscience very well for very long. They were never intended, however, to lower a curtain of ignorance over everyday physiology. In raising these curtains, we unveil a range of dynamics, resolvable in the data collection and as-one-goes analysis by computers built into smaller and smaller devices, for a continued self-surveillance of the normal and for an individualized detection of the abnormal. The current medical art based on spotchecks interpreted by reference to a time-unqualified normal range can become a science of time series with tests relating to the individual in inferential statistical terms. This is already doable for the case of blood pressure, but eventually should become possible for many other variables interpreted today only based on the quicksand of clinical trials on groups. These ignore individual differences and hence the individual's needs. Chronomics (mapping time structures) with the major aim of quantifying normalcy by dynamic reference values for detecting earliest risk elevation, also yields the dividend of allowing molecular biology to focus on the normal as well as on the grossly abnormal.

Role of endothelin in human hypertension

Endothelin-1 (ET-1) is a pleiotropic hormone produced primarily by the endothelium. Synthesis of ET-1 is stimulated by the major signals of cardiovascular stress, such as vasoactive agents (angiotensin II, norepinephrine, vasopressin, and bradykinin), cytokines (e.g., tumor necrosis factor alpha and transforming growth factor beta), and other factors, including thrombin and mechanical stress. ET-1 induces vasoconstriction, is proinflammatory, promotes fibrosis, and has mitogenic potential, important factors in the regulation of vascular tone, arterial remodeling, and vascular injury. These effects are mediated via two receptor types, ETA and ETB. The role ET-1 plays in normal cardiovascular homeostasis and in mild essential hypertension in humans is unclear. However, certain groups of essential hypertensive patients may have ET-1-dependent hypertension, including blacks (subjects of African descent), salt-sensitive hypertensives, patients with low renin hypertension, and those with obesity and insulin resistance. ET-1 has also been implicated in severe hypertension, heart failure, atherosclerosis, and pulmonary hypertension. In all of these conditions, plasma immunoreactive ET levels are elevated and tissue ET-1 expression is increased. Accordingly, it is becoming increasingly apparent that ET-1 plays an important role in cardiovascular disease and in some forms of hypertension in humans. Data from clinical trials using combined ETA-ETB receptor blockers have already demonstrated significant blood-pressure-lowering effects. Thus, targeting the endothelin system may have important therapeutic potential in the treatment of hypertension, particularly by contributing to the prevention of target organ damage and the management of cardiovascular disease.

Recent advances in the treatment of erectile dysfunction in patients with diabetes mellitus

OBJECTIVE

To present current information on the pathogenesis of and available therapeutic options for erectile dysfunction (ED) in patients with diabetes.

METHODS

We provide a detailed review of the following topics: (1) peripheral and central neurotransmitter pathways involved in the penile erectile process (for example, nitric oxide, acetylcholine, vasoactive intestinal polypeptide, and prostaglandin E(1)), (2) pathogenesis of ED in patients with diabetes (vascular insufficiency, endothelial dysfunction, and autonomic neuropathy), (3) currently available treatment options for ED and their advantages and disadvantages, (4) potential new avenues for future research, and (5) the possibility of preventive treatment.

RESULTS

Clearly a need exists for effective treatment options for ED in patients with diabetes. Because the development of ED in patients with diabetes is often caused by several interrelated mechanisms, including vascular disease, endothelial dysfunction, autonomic neuropathy, hormone imbalance, and certain medications, a thorough understanding of the various pathways involved in penile erection and their modulation in diabetes is essential for physicians to design an effective treatment plan. Interventions that modulate the erectile pathway at different points include therapies that enhance the erectile mechanism (amplification of the nitric oxide pathway), inhibit the detumescence mechanism, or affect the final common pathway by augmenting smooth muscle relaxation. Oral therapy, intracavernosal injections, transurethral pellets, combination therapy, and surgical procedures are available treatment strategies.

CONCLUSION

Despite the availability of many treatment options for ED, early intervention and prevention (by such measures as improved glycemic control and general reduction of associated risk factors) should be emphasized because many of the diabetes-related complications leading to ED are irreversible.

Feedsidewards: intermodulation (strictly) among time structures, chronomes, in and around us, and cosmo-vasculo-neuroimmunity. About ten-yearly changes: what Galileo missed and Schwabe found

The spectrum of biological rhythms is extended far beyond circadians, circannuals, and ultradians, such as 1.5-hourly melatonin and 8-hourly endothelin-1 (ET-1) rhythms by statistics of natality, growth, morbidity, and mortality, some covering decades or centuries on millions of individuals. These reveal infradian cycles to be aligned with half-weekly rhythms in ET-1, weekly and half-yearly ones in melatonin, and even longer--about 50-, about 20-, and about 10-year cycles found in birth statistics. About daily, weekly, yearly, and ten-yearly patterns are also found in mortality from myocardial infarctions; the 10-yearly ones are also in heart rate and its variability; in steroid excretion, an aspect of resistance, for example, to bacteria; and in the genetic changes of the bacteria themselves. Automatic physiological measurements cover years and, in one case, cover a decade; the latter reveal an about 10-year (circadecennial) cycle. ECGs, covering months beat-to-beat, reveal circaseptans, gaining prominence in response to magnetic storms or after coronary artery bypass grafting. A spectrum including cycles from fractions of 1 Hz to circasemicentennians is just one element in biological time structures, chronomes. Chaos, trends, and any unresolved variability are the second to fourth elements of chronomes. Intermodulations, feedsidewards, account for rhythmically and thus predictably recurring quantitive differences and even for opposite treatment effects of the same total dose(s) of (1) immunomodulators inhibiting or stimulating DNA labeling of bone in health or speeding up versus slowing down a malignant growth and thus shortening or lengthening survival time, or (2) raising or lowering blood pressure or heart rate in the vascular aspect of the body's defense. Latitude-dependent competing photic and nonphotic solar effects upon the pineal are gauged by alternating yearly (by daylight) and half-yearly (by night) signatures of circulating melatonin at middle latitudes and by half-yearly signatures at noon near the pole. These many (including novel near 10-yearly) changes, for example, in 17-ketosteroid excretion, heart rate, heart rate variability, and myocardial infarction in us and those galactic, solar, and geophysical ones around us have their own special signatures and contribute to a cosmo-vasculo-immunity and, if that fails, to a cosmo(immuno?) pathology.

About 8- and approximately 84-h rhythms in endotheliocytes as in endothelin-1 and effect of trauma

Population densities (PD) of capillaries (C) and endotheliocytes (E) were determined in pinnal dermis of C57BL mice before and after trauma. Moving (and overall) least-squares spectra before trauma detected in EPD (versus CPD) pronounced 3.5-day (circasemiseptan) and 8-h oscillations corresponding to components of the endothelin-1 chronome in human blood plasma reported earlier. Circadians were more pronounced in CPD. After trauma, circasemiseptan oscillations appeared also in CPD; their period gradually shortened and in two weeks split into about 2.5- and about 4.5-day oscillations; and circadian components became very pronounced. The pre-traumatic chronome was not restored within three weeks following trauma.

Interaction of endothelin-1 with vasoactive factors in mediating glucose-induced increased permeability in endothelial cells

Alteration of endothelins (ET) and/or their receptors may be important in mediating vascular dysfunction in diabetes. We investigated mechanisms regulating ET-1 expression in human umbilical vein endothelial cells (HUVEC) in response to glucose and the functional significance of these mechanisms. Permeability across HUVEC, grown in medium containing either low (5 mmol/l) or high (25 mmol/l) D-glucose were investigated. L-glucose was used as a control. ET-1, ET(A), and ET(B) mRNA were assessed by semiquantitative RT-PCR. ET-1 immunoreactivity and F-actin microfilament assembly were investigated using confocal microscopy. Increased transendothelial permeability was noted in cells cultured in high glucose or when the cells grown in low (physiologic) glucose were incubated with ET-1, vascular endothelial growth factor (VEGF), or N (G) -nitro-L-arginine methyl ester but not when they were incubated with ET-3, N(G)-nitro-D-arginine methyl ester, or L-glucose. Increased permeability was associated with increased ET-1, ET(A), and ET(B) mRNA expression and augmented ET-1 immunoreactivity. High glucose induced increased permeability, increased ET-1, ET(A), and ET(B) mRNA expression. ET-1 immunoreactivity was blocked by the protein kinase C (PKC) inhibitor chelerythrine, the specific PKC isoform inhibitor 379196, VEGF-neutralizing antibody, or the ET(A) blocker TBC11251, but was not blocked by the specific ET(B) blocker BQ788 or by a VEGF-non-neutralizing antibody. Increased permeability was also associated with deranged F-actin assembly in the endothelial cells and by derangement of endothelial cell junctions as assessed by electron microscopy. Data from this study suggest that high glucose-induced increased permeability may be induced through increased ET-1 expression and disorganization of F-actin assembly. ET-1 expression and increased permeability may occur secondary to PKC isoform activation and may be modulated by VEGF and nitric oxide.

Peripheral vascular disease and renal transplant artery stenosis: a reappraisal of transplant renovascular disease

BACKGROUND

Renal transplant artery stenosis (RTAS) continues to be a problematic, but potentially correctable, cause of post-transplant hypertension and graft dysfunction. Older transplant recipients, prone to peripheral vascular disease (PVD), may have pseudoRTAS with PVD involving their iliac system.

METHODS

We retrospectively analyzed 819 patients who underwent kidney transplantation between 1993 and 1997 to determine the contribution of pseudoRTAS to renal transplant renovascular disease. Univariate analyses were performed for donor and recipient variables, including age, weight, gender, race, renal disease, cholesterol and creatinine values, human leukocyte antigen (HLA) matching, cytomegalovirus (CMV) infection, and immunosuppressive medications. Significant variables were then analyzed by a Cox proportional hazards model.

RESULTS

Ninety-two patients (11.2%) underwent renal transplant arteriogram (Agram) or magnetic resonance angiography (MRA) for suspected RTAS. RTAS or pseudoRTAS, defined as one or more hemodynamically significant lesions in the transplant artery or iliac system, was evident in 44 patients (5.4%). Variables significantly associated with RTAS by univariate analysis were weight at the time of transplant (p = 0.0258), male gender (p = 0.034), discharge serum creatinine > 2 mg/dL (p = 0.0041), and donor age (p = 0.0062). Variables significantly associated with pseudoRTAS by univariate analysis were weight at the time of transplant (p = 0.0285), recipient age (p = 0.0049), insulin-dependent diabetes mellitus (IDDM; p = 0.0042), panel reactive antibody (PRA) at transplant (p = 0.018), and body mass index (p = 0.04). Weight at transplant and donor age remained significantly associated with an increased risk for RTAS in a multivariate stepwise Cox proportional hazards model. IDDM, transplant PRA, weight at transplant, and donor age were significantly associated with an increased risk for pseudoRTAS in a multivariate stepwise Cox proportional hazards model. Importantly, both RTAS and pseudoRTAS were associated with poorer graft survival (p < 0.007 for each).

CONCLUSIONS

Renal transplant renovascular disease encompasses pre-existing PVD acting as pseudoRTAS, as well as classical RTAS. Efforts to identify and correct renal transplant renovascular disease of either nature are important, given its negative impact on graft survival.

Influence of non-insulin-dependent diabetes mellitus on plasma endothelin-1 levels in patients with advanced atherosclerosis

Endothelin-1 (ET-1) is an endothelium-derived vasoactive peptide with mitogen properties. Increased circulating ET-1 levels were found in patients with atherosclerosis as well as in patients with non-insulin-dependent diabetes mellitus (NIDDM) suggesting a role in the pathogenesis of these disorders. The aim of the present study was to ascertain the influence of the NIDDM on plasma ET-1 levels in patients with advanced atherosclerotic lesions. The circulating ET-1 levels were measured in 16 NIDDM patients (68.4 +/- 8.4 years) with macroangiopathy and in ten patients (65.3 +/- 11 years) with atherosclerosis without NIDDM. Twenty-two healthy subjects (43.1 +/- 18.3 years) served as controls. Circulating ET-1 levels were higher in NIDDM patients (6.8 +/- 2.8 pg/mL) than both controls (3.1 +/- 1 pg/mL; p < 0.001) and patients with vascular disease but without NIDDM (4.7 +/- 1.6 pg/mL; p < 0.04). No significant relationship was found between age and ET-1 concentrations, and no differences were noted between men and women in the control group. This study demonstrated that circulating ET-1 levels are increased in patients with atherosclerosis and that those with NIDDM showed the highest ET-1 levels. These observations strongly support a role for ET-1 in the pathogenesis of atherosclerosis and also suggest that this peptide may be involved in the development of atherosclerotic lesions in the NIDDM. We speculated that chronic exposure to hyperinsulinemia and hypertriglyceridemia in the diabetic patients could account for the increased ET-1 levels found in these patients.

The role of endothelin in hypertension

The endothelins are 21-amino-acid peptides which may play a role in the pathogenesis of hypertension. There is increasing evidence that the endothelins have a central function in mediating end-organ damage in hypertension, and that important effects of endothelin in the pathogenesis of hypertension may be based on the interactions of the endothelins and the renin-angiotensin and the nitric oxide systems.

About 8-hour variation of circulating human endothelin-1

Plasma endothelin-1 (ET-1) and cortisol were measured around the clock at hourly intervals on 7 clinically healthy, diurnally active, nocturnally resting subjects 22-27 years of age. The circadian rhythm in cortisol is demonstrated for each subject (p < or = 0.020) as well as on a group basis (p = 0.002), peaking in the morning. By contrast, the circadian variation of ET-1 is statistically significant in only one of the subjects, and it is not detected for the group as a whole (p > 0.20). Instead, ET-1 is characterized by an about 8-h component (p < 0.001) that is not found for cortisol.

About-half-weekly (circasemiseptan) component of the endothelin-1 (ET-1) chronome and vascular disease risk

Plasma ET-1 was measured around the clock on different calendar dates in healthy subjects and in subjects with diabetes and/or with high blood pressure and/or a history of vascular complications (HVDR). A transverse approach, with each subject contributing a single 24-h mean, assessed any about-weekly or half-weekly variation in ET-1. A circasemiseptan component resolved by single cosinor for nondiabetic (but not for diabetic) HVDR subjects (p = 0.010) differs in its timing of overall high values (p < 0.050) from that found in healthy subjects (p = 0.006). The results are aligned with circasemiseptan patterns in other circulatory variables and morbidity/mortality statistics.