SummaryVascular endothelial dysfunction occurs during the human aging process, and it is considered as a crucial event in the development of many vasculopathies. We investigated the underlying mechanisms of this process, particularly those related with oxidative stress and inflammation, in the vasculature of subjects aged 18-91 years without cardiovascular disease or risk factors. In isolated mesenteric microvessels from these subjects, an age-dependent impairment of the endotheliumdependent relaxations to bradykinin was observed. Similar results were observed by plethysmography in the forearm blood flow in response to acetylcholine. In microvessels from subjects aged less than 60 years, most of the bradykinin-induced relaxation was due to nitric oxide release while the rest was sensitive to cyclooxygenase (COX) blockade. In microvessels from subjects older than 60 years, this COX-derived vasodilatation was lost but a COX-derived vasoconstriction occurred. Evidence for age-related vascular oxidant and inflammatory environment was observed, which could be related to the development of endothelial dysfunction. Indeed, aged microvessels showed superoxide anions (O 2 ) ) and peroxynitrite (ONOO ) ) formation, enhancement of NADPH oxidase and inducible NO synthase expression. Pharmacological interference of COX, thromboxane A 2 ⁄ prostaglandin H 2 receptor, O 2, inducible NO synthase, and NADPH oxidase improved the age-related endothelial dysfunction. In situ vascular nuclear factor-jB activation was enhanced with age, which correlated with endothelial dysfunction. We conclude that the age-dependent endothelial dysfunction in human vessels is due to the combined effect of oxidative stress and vascular wall inflammation.

1 The aim of this work was to study the in¯uence of the metabolic control, estimated by the levels of glycosylated haemoglobin in total blood samples (HbA 1c ), in developing vascular endothelial dysfunction in streptozotocin-induced diabetic rats. Four groups of animals with di erent levels of insulin treatment were established, by determining HbA 1c values in 5.5 to 7.4%, 7.5 to 9.4%, 9.5 to 12% and 412%, respectively. 2 The parameters analysed were: (1) the endothelium-dependent relaxations to acetylcholine (ACh) in isolated aorta and mesenteric microvessels; (2) the vasodilator responses to exogenous nitric oxide (NO) in aorta; and (3) the existence of oxidative stress by studying the in¯uence of the free radical scavenger superoxide dismutase (SOD) on the vasodilator responses to both ACh and NO. 3 In both isolated aortic segments and mesenteric microvessels, the endothelium-mediated concentration-dependent relaxant responses elicited by ACh were signi®cantly decreased when the vessels were obtained from diabetic animals but only with HbA 1c values higher than 7.5%. There was a high correlation between HbA 1c levels and the impairment of ACh-induced relaxations, measured by pD 2 values. 4 The concentration-dependent vasorelaxant responses to NO in endothelium-denuded aortic segments were signi®cantly reduced only in vessels from diabetic animals with HbA 1c values higher than 7.5%. Again, a very high correlation was found between the HbA 1c values and pD 2 for NO-evoked responses. 5 In the presence of SOD, the responses to ACh or NO were only increased in the segments from diabetic rats with HbA 1c levels higher than 7.5%, but not in those from non-diabetic or diabetic rats with a good metabolic control (HbA 1c levels 57.5%). 6 These results suggest the existence of: (1) a close relation between the degree of endothelial dysfunction and the metabolic control of diabetes, estimated by the levels of HbA 1c ; and (2) an increased production of superoxide anions in the vascular wall of the diabetic rats, which is also related to the metabolic control of the disease.

Aims/hypothesis. In a model of streptozotocin-induced Type 1 diabetes mellitus in rats of 9 weeks duration, we analysed time associations between the development of hyperglycaemia, early and intermediate glycosylation Amadori adducts, or AGE compared with enhancement of oxidative stress and endothelial dysfunction.Methods. Endothelial function was tested at several stages of streptozotocin-induced diabetes and after treatment with insulin, resulting in different concentrations of blood glucose, glycosylated haemoglobin (an Amadori adduct), and AGE. Other animals were studied antagonising the formation of AGE with aminoguanidine. Results. Relaxation in response to acetylcholine (1 nmol/l to 10 µmol/l) was tested in isolated segments from aorta or mesenteric microvessels. Impairment of endothelium-dependent relaxations occurred after 2 weeks of untreated diabetes. Preincubation of vessels affected with 100 U/ml superoxide dismutase improved the relaxations to acetylcholine, along the time-course of the endothelial impairment. This indicates the participation of reactive oxygen species on diabetic endothelial dysfunction. The impairment of endothelium-dependent relaxations was recovered after 3 more weeks of insulin treatment. Aminoguanidine treatment did not modify this pattern of development. The time course of the rise and disappearance of endothelial dysfunction showed a higher correlation with glycosylated haemoglobin concentrations than with blood glucose or serum AGE. Conclusion/interpretation. Enhancement of early and intermediate Amadori adducts of protein glycosylation was the factor showing a better relation with the development of endothelium impairment. These results are consistent with a role for these products in the development of diabetic vasculopathy. [Diabetologia (2003) 46:556-566] Keywords Diabetes mellitus, endothelial dysfunction, nitric oxide, superoxide anions, hyperglycaemia, Amadori adducts, advanced glycosylation end-products. Endothelial dysfunction seems to be a key factor in the development of diabetic vascular complications. The impairment of endothelium-dependent vasodilatations is an early event occurring in diabetic patients [1,2,3] and animal diabetic models [4,5,6, 7]. Enhanced oxidative stress in diabetes mellitus has been also shown [8,9], which can be detected by peroxidation products [10] or by increased generation of reactive oxygen species (ROS), mainly superoxide anions [11]. Indeed, enhanced oxidative stress is proposed to be a major cause of diabetic endothelial dysfunction [12,13].There is also increasing evidence that diabetic endothelial dysfunction and oxidative stress are a conse-

Objective. Healthcare professionals who work in palliative care units face stressful life events on a daily basis, most notably death. For this reason, these professionals must be equipped with the necessary protective resources to help them cope with professional and personal burnout. Despite the well-recognized importance of the construct “meaning of work,” the role of this construct and its relationship with other variables is not well-understood. Our objective is to develop and evaluate a model that examines the mediating role of the meaning of work in a multidisciplinary group of palliative care professionals. Using this model, we sought to assess the relationships between meaning of work, perceived stress, personal protective factors (optimism, self-esteem, life satisfaction, personal growth, subjective vitality), and sociodemographic variables. Method. Professionals (n = 189) from a wide range of disciplines (physicians, psychologists, nurses, social workers, nursing assistants, physical therapists, and chaplains) working in palliative care units at hospitals in Madrid and the Balearic Islands were recruited. Sociodemographic variables were collected and recorded. The following questionnaires were administered: Meaning of Work Questionnaire, Perceived Stress Questionnaire, Life Orientation Test-Revised, Satisfaction with Life Scale, Subjective Vitality Scale, Rosenberg Self-Esteem Scale, and the Personal Growth Scale. Result. The explanatory value of the model was high, explaining 49.5% of the variance of life satisfaction, 43% of subjective vitality, and 36% of personal growth. The main findings of this study were as follow: (1) meaning of work and perceived stress were negatively correlated; (2) optimism and self-esteem mediated the effect of stress on the meaning attached to work among palliative care professionals; (3) the meaning of work mediated the effect of stress on subjective vitality, personal growth, and life satisfaction; and (4) vitality and personal growth directly influenced life satisfaction. Significance of results. The proposed model showed a high explanatory value for the meaning professionals give to their work and also for perceived stress, personal protective factors, and sociodemographic variables. Our findings could have highly relevant practical implications for designing programs to promote the psychological well-being of healthcare professionals.

In patients with diabetes type 1, glycaemic control determines the functioning of the NO system by a reversible mechanism involving superoxide anions. This finding provides an explanation of the relationship between glycaemic control and vascular complications in diabetes.