Cardiopulmonary bypass leads to microvascular impairment of jejunal microcirculation, which is associated with the upregulation of endothelin-1 and endothelin subtype A. The administration of vasopressin minimizes these cardiopulmonary bypass-associated alterations.

CPB does not significantly affect rectosigmoidal mucosal microcirculation; however, it upregulates ET-1, ETA , and ETB . Vasopressin blunts the CPB-induced elevation of ET-1, ETA , and ETB and induces rectosigmoidal mucosal ischemia during CPB.

Urbanization of the Ovahimba people is associated with an increasing prevalence of disorders of glucose metabolism and other unfavorable metabolic parameters. Besides changes of lifestyle, this may be attributed to an increased cortisol exposure of the Ovahimba people living in an urban environment.

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Background/Aim: Upper gastrointestinal bleeding (UGIB) is one of the most frequent gastrointestinal complications after cardiac surgery with cardiopulmonary bypass (CPB). Endothelin expression and microcirculatory dysfunction have been shown to be involved in UGIB. The aim of this study was to analyze the effect of vasopressin during CPB on the gastric mucosal microcirculation and the involvement of the endothelin system. Methods: Eighteen pigs were randomized into three groups (n = 6 each): group I = sham, group II = CPB (1-hour CPB) and group III = CPB + vasopressin (1-hour CPB and vasopressin administration during CPB to maintain baseline arterial pressure). All animals were observed for a further 90 min after termination of CPB. Systemic hemodynamics as well as blood flow and oxygen saturation of the gastric mucosa were measured continuously. At the end of the experiment, the gastric mucosal expressions of endothelin-1 (ET-1) and its receptor subtypes A (ET_A) and B (ET_B) were determined by polymerase chain reaction. Gastric mucosal injury, apoptotic cell death and leukocytic infiltration were determined by histology and immunohistochemical analyses of cleaved caspase-3 and myeloperoxidase. Results: CPB decreased gastric microvascular perfusion, which was associated with an increased expression of ET-1 and ET_A. Vasopressin aggravated the CPB-associated malperfusion, whereas it completely abrogated the upregulation of ET-1 and ET_A. Interestingly, vasopressin did not induce gastric mucosal morphologic injury, leukocytic infiltration or apoptotic cell death. Conclusion: Vasopressin aggravates CPB-associated microvascular malperfusion of the gastric mucosa but does not induce gastric mucosal injury.

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The prevalence of osteoporosis in Sub-Saharan African (SSA) countries is low, however, as urbanization takes root, it is predicted that bone health will decrease dramatically. The bone health of the semi-nomadic Ovahimba people of Namibia was investigated in the context of urbanization and changes of the sociocultural environment. Furthermore, data on bone health in SSA countries is scarce; there exists no ethnic-specific reference group for people of black origin. Included in the study were 98 urban and rural living Ovahimba people. Quantitative ultrasound was performed, sunrise/sunset saliva cortisol concentrations was measured and a questionnaire was conducted. There was no significant difference in the QUS parameters, however, after adjustment for confounders, SOS and SI differed significantly. The saliva cortisol concentrations differed significantly. After adjustment for confounders, saliva cortisol was significantly negatively correlated to SOS (r= -0.27, p = 0.021) giving an indication for an association between cortisol concentration and QUS parameters. The urban group furthermore showed a nutritional transition. Even though the bone health of the Ovahimba is very good, first signs of the adverse effects of urbanization were detected. Beside changes of lifestyle, this may be attributed to an increased cortisol exposure of the Ovahimba people living in an urban environment due to an increased psychosocial stress.