Electromagnetic vacuum fluctuations around a cosmic string in de Sitter spacetime

The electromagnetic field correlators are evaluated around a cosmic string in background of $(D+1)$-dimensional dS spacetime assuming that the field is prepared in the Bunch-Davies vacuum state. The correlators are presented in the decomposed form where the string-induced topological parts are explicitly extracted. With this decomposition, the renormalization of the local vacuum expectation values (VEVs) in the coincidence limit is reduced to the one for dS spacetime in the absence of the cosmic string. The VEVs of the squared electric and magnetic fields, and of the vacuum energy density are investigated. Near the string they are dominated by the topological contributions and the effects induced by the background gravitational field are small. In this region, the leading terms in the topological contributions are obtained from the corresponding VEVs for a string on the Minkowski bulk multiplying by the conformal factor. At distances from the string larger than the curvature radius of the background geometry, the pure dS parts in the VEVs dominate. In this region, for spatial dimensions $D>3$, the influence of the gravitational field on the topological contributions is crucial and the corresponding behavior is essentially different from that for a cosmic string on the Minkowski bulk. There are well-motivated inflationary models which produce cosmic strings. We argue that, as a consequence of the quantum-to-classical transition of super-Hubble electromagnetic fluctuations during inflation, in the postinflationary era these strings will be surrounded by large scale stochastic magnetic fields. These fields could be among the distinctive features of the cosmic strings produced during the inflation and also of the corresponding inflationary models.Comment: 19 pages, 2 figure

Electromagnetic vacuum densities induced by a cosmic string

We investigate the influence of a generalized cosmic string in (D+1) -dimensional spacetime on the local characteristics of the electromagnetic vacuum. Two special cases are considered with flat and locally de Sitter background geometries. The topological contributions in the vacuum expectation values (VEVs) of the squared electric and magnetic fields are explicitly separated. Depending on the number of spatial dimensions and on the planar angle deficit induced by the cosmic string, these contributions can be either negative or positive. In the case of the flat bulk, the VEV of the energy-momentum tensor is evaluated as well. For the locally de Sitter bulk, the influence of the background gravitational field essentially changes the behavior of the vacuum densities at distances from the string larger than the curvature radius of the spacetime.Comment: 19 pages, 5 figures. arXiv admin note: text overlap with arXiv:1706.0074

Electromagnetic vacuum stresses and energy fluxes induced by a cosmic string in de Sitter spacetime

For the electromagnetic field in (D+1)-dimensional locally de Sitter (dS) spacetime, we analyze the effects of a generalized cosmic string type defect on the vacuum expectation value of the energy-momentum tensor. For the Bunch-Davies vacuum state, the topological contributions are explicitly extracted in both the diagonal and off-diagonal components. The latter describes the presence of radially directed energy flux in the vacuum state. It vanishes for $D=3$ because of the conformal invariance of the electromagnetic field and is directed towards the cosmic string for $D\geq 4$ . The topological contributions in the vacuum stresses are anisotropic and, unlike to the geometry of a cosmic string in the Minkowski spacetime, for $D>3$ the stresses along the directions parallel to the string core differ from the energy density. Depending on the planar angle deficit and the distance from the cosmic string, the corresponding expectation values can be either positive or negative. Near the cosmic string the effect of the gravitational field on the diagonal components of the topological part is weak. The spacetime curvature essentially modifies the behavior of the topological terms at proper distances from the cosmic string larger than the dS curvature radius. In that region, the topological contributions in the diagonal components of the energy-momentum tensor decay in inverse proportion to the fourth power of the proper distance and the energy flux density behaves as inverse-fifth power for all values of the spatial dimension $D$. The exception is the energy density in the special case $D=4$.Comment: 23 pages, 4 figures, Discussion adde

Features of heart failure with preserved ejection fraction (HFpEF) in diabetic patients with resistant hypertension

BACKGROUND: It is expected that a steady increase in the incidence of diabetes and resistant hypertension (RHTN), along with an increase in life expectancy, will lead to a noticeable increase in the proportion of patients with heart failure with preserved ejection fraction (HFpEF). At the same time, data on the frequency of HFpEF in a selective group of patients with RHTN in combination with diabetes are still lacking, and the pathophysiological and molecular mechanisms of its formation have not been yet studied sufficiently.AIM: To assess the features of the development HFpEF in diabetic and non-diabetic patients with RHTN, as well as to determine the factors associated with HFpEF.MATERIALS AND METHODS: In the study were included 36 patients with RHTN and type 2 diabetes mellitus (DM) (mean age 61.4 ± 6.4 years, 14 men) and 33 patients with RHTN without diabetes, matched by sex, age and level of systolic blood pressure (BP). All patients underwent baseline office and 24-hour BP measurement, echocardiography with assess diastolic function, lab tests (basal glycemia, HbA1c, creatinine, aldosterone, TNF-alpha, hsCRP, brain naturetic peptide, metalloproteinases of types 2, 9 (MMP-2, MMP-9) and tissue inhibitor of MMP type 1 (TIMP-1)). HFpEF was diagnosed according to the 2019 AHA/ESC guidelines.RESULTS: The frequency of HFpEF was significantly higher in patients with RHTN with DM than those without DM (89% and 70%, respectively, p=0.045). This difference was due to a higher frequency of such major functional criterion of HFpEF as E/e’≥15 (p=0.042), as well as a tendency towards a higher frequency of an increase in left atrial volumes (p=0.081) and an increase in BNP (p=0.110). Despite the comparable frequency of diastolic dysfunction in patients with and without diabetes (100% and 97%, respectively), disturbance of the transmitral blood flow in patients with DM were more pronounced than in those without diabetes. Deterioration of transmitral blood flow and pseudo-normalization of diastolic function in diabetic patients with RHTN have relationship not only with signs of carbohydrate metabolism disturbance, but also with level of pulse blood pressure, TNF-alfa, TIMP-1 and TIMP-1 / MMP-2 ratio, which, along with the incidence of atherosclerosis, were higher in patients with DM than in those without diabetes.CONCLUSIONS: Thus, HFpEF occurs in the majority of diabetic patients with RHTN. The frequency of HFpEF in patients with DN is significantly higher than in patients without it, which is associated with more pronounced impairments of diastolic function. The progressive development of diastolic dysfunction in patients with diabetes mellitus is associated not only with metabolic disorders, but also with increased activity of chronic subclinical inflammation, profibrotic state and high severity of vascular changes

Cerebrovascular disorders in patients with type 2 diabetes mellitus and resistant hypertension

BACKGROUND: Diabetes mellitus (DM) and hypertension are risk factors for cerebral stroke, which are exacerbated by the combination of these diseases. Identifying the factors involved in the development of subclinical brain damage could change the therapeutic strategy for protecting the brain.AIM: to study severity of MRI- sings of brain damage and to identify factors associated with their development in patients with type 2 diabetes and RHTN.MATERIALS AND METHODS: 46 patients with type 2 DM and RHTN were included in a single-center observational uncontrolled study. Patients underwent brain MRI (1.5 Tesla) with calculation of Evans’s index (EI), clinical and lab examinations (HbA1c, glucose, insulin, C-peptide, leptin, resistin, TNF- α, hsCRP, blood aldosterone, insulin-like growth factor-1 (IGF-1)), measurement of the office and ambulatory blood pressure (BP), assessment of peripheral and cerebral vasoreactivity (test with hyperventilation and breath holding).RESULTS: The most frequent MR brain changes were white matter lesions (WML) in periventricular region (PVR) (89%), focal WML (52%) and expansion both of the ventricles (45%) and subarachnoid spaces (65%). Multiple direct correlations were revealed between parameters of carbohydrate metabolism with the degree of WML in PVR and the density of the MR-signal in the basal nucleus (BN), as well as with EI. Adipokines had a direct relationship with the size of the chiasmatic cistern and IE (for resistin), as well as with the density of the MR signal from the BN and IE (for leptin), that was also directly related to the IGF-1 level. The aldosterone level positively correlated with the size of III ventricle. An increase in TNF-α and hsCRP was accompanied by an increase in the density of the MR-signal in the PVR. Impairment of cerebrovascular reactivity is associated with an increase in the density of the MR-signal in PVR and with indirect signs of cerebral atrophy (increase in EI, the size of cisterns and lateral ventricles). Impairment of peripheral vasoreactivity had direct relationship with EI and the expansion of the III ventricle. There were no direct correlations between the severity of MR-sings of brain damage and BP levels.CONCLUSION: The combination of type 2 DM with RHTN is characterized by a high frequency of WML and liquorodynamics disturbances, which related with metabolic, neurohormonal and hemodynamic factors in the absence of a direct relationship with the degree of BP increas

Mycobacterial PIMs Inhibit Host Inflammatory Responses through CD14-Dependent and CD14-Independent Mechanisms

Mycobacteria develop strategies to evade the host immune system. Among them, mycobacterial LAM or PIMs inhibit the expression of pro-inflammatory cytokines by activated macrophages. Here, using synthetic PIM analogues, we analyzed the mode of action of PIM anti-inflammatory effects. Synthetic PIM1 isomer and PIM2 mimetic potently inhibit TNF and IL-12 p40 expression induced by TLR2 or TLR4 pathways, but not by TLR9, in murine macrophages. We show inhibition of LPS binding to TLR4/MD2/CD14 expressing HEK cells by PIM1 and PIM2 analogues. More specifically, the binding of LPS to CD14 was inhibited by PIM1 and PIM2 analogues. CD14 was dispensable for PIM1 and PIM2 analogues functional inhibition of TLR2 agonists induced TNF, as shown in CD14-deficient macrophages. The use of rough-LPS, that stimulates TLR4 pathway independently of CD14, allowed to discriminate between CD14-dependent and CD14-independent anti-inflammatory effects of PIMs on LPS-induced macrophage responses. PIM1 and PIM2 analogues inhibited LPS-induced TNF release by a CD14-dependent pathway, while IL-12 p40 inhibition was CD14-independent, suggesting that PIMs have multifold inhibitory effects on the TLR4 signalling pathway