Martin Luther University of Halle-Wittenberg

About: Martin Luther University of Halle-Wittenberg is a education organization based out in Halle, Germany. It is known for research contribution in the topics: Population & Liquid crystal. The organization has 20232 authors who have published 38773 publications receiving 965004 citations. The organization is also known as: MLU & University of Wittenberg.

Storage and stability of organic carbon in soils as related to depth, occlusion within aggregates, and attachment to minerals

Abstract: Conceptual models suggest that stability of or- ganic carbon (OC) in soil depends on the source of plant litter, occlusion within aggregates, incorporation in organo- mineral complexes, and location within the soil profile. Den- sity fractionation is a useful tool to study the relevance of OC stabilization in aggregates and in association with min- erals, but it has rarely been applied to full soil profiles. We aim to determine factors shaping the depth profiles of phys- ically unprotected and mineral associated OC and test their relevance for OC stability across a range of European soils that vary in vegetation, soil types, parent material, and land use. At each of the 12 study sites, 10 soil cores were sam- pled to 60 cm depth and subjected to density separation. Bulk soil samples and density fractions (free light fractions - fLF, occluded light fractions - oLF, heavy fractions - HF) were analysed for OC, total nitrogen (TN), 13 C, and 1 14 C. Bulk samples were also incubated to determine CO2 evolution per g OC in the samples (specific mineralization rates) as an in- dicator for OC stability. Depth profiles of OC in the light fraction (LF-OC) matched those of roots for undisturbed grassland and forest sites, suggesting that roots are shaping the depth distribution of LF-OC. Organic C in the HF declined less with soil depth than LF-OC and roots, especially at grassland sites. The de- crease in 1 14 C (increase in age) of HF-OC with soil depth was related to soil pH as well as to dissolved OC fluxes. This indicates that dissolved OC translocation contributes to the formation of subsoil HF-OC and shapes the 1 14 C profiles. The LF at three sites were rather depleted in 14 C, indi- cating the presence of fossil material such as coal and lig- nite, probably inherited from the parent material. At the other sites, modern 1 14 C signatures and positive correlations be- tween specific mineralization rates and fLF-OC indicate the fLF is a potentially available energy and nutrient source for subsurface microorganisms throughout the profile. Declining specific mineralization rates with soil depth confirm greater stability of OC in subsoils across sites. The overall impor- tance of OC stabilization by binding to minerals was demon- strated by declining specific mineralization rates with in- creasing contributions of HF-OC to bulk soil OC, and the low 1 14 C values of HF-OC. The stability of HF-OC was greater in subsoils than in topsoils; nevertheless, a portion of HF-OC was active throughout the profile. While quanti- tatively less important than OC in the HF, consistent older ages of oLF-OC than fLF-OC suggest that occlusion of LF- OC in aggregates also contributes to OC stability in subsoils. Overall, our results indicate that association with minerals is the most important factor in stabilization of OC in soils, irre- spective of vegetation, soil type, and land use.

Angiotensin II Induces LOX-1, the Human Endothelial Receptor for Oxidized Low-Density Lipoprotein

Abstract: Background—Oxidatively modified LDL (oxLDL) plays an important role in the development of atherosclerosis. OxLDL effects, eg, foam cell formation, are mediated in part by the classic scavenger receptor, whereas other effects may involve the recently cloned endothelial oxLDL receptor, LOX-1 (lectinlike oxLDL receptor-1), which is distinct from macrophage scavenger receptors. Because the regulation of LOX-1 must still be defined, we investigated whether LOX-1 is regulated by the potentially proatherosclerotic stimulant angiotensin II (Ang II). Methods and Results—Using competitive reverse transcription–polymerase chain reaction (RT-PCR), we quantified mRNA expression of LOX-1 in primary cultures of human umbilical vein endothelial cells (HUVECs). After treatment with Ang II for 3 hours (1 nmol/L to 1 μmol/L), LOX-1 mRNA was concentration-dependently induced (from 6.9±1.4 to 23.1±5.5 relative units [RU] by 1 μmol/L Ang II; P<0.05). The angiotensin II type 1 (AT1) receptor antagonist losartan prevented this i...

Thrombolytic therapy in pregnancy

Abstract: Pregnancy due to its physiological changes is a procoagulant state. The rate of cardiac valve prosthesis thrombosis, deep venous thrombosis and pulmonary embolism are all increased. Thrombolytic therapy with tissue plasminogen activator (rt-PA) is an approved therapy for ischemic stroke, myocardial infarction, pulmonary embolism and thrombosis of cardiac valve prosthesis. However, there are no data from controlled randomized trials in pregnant patients. Thrombolytic therapy has been rarely used in pregnancy with only 28 cases of rt-PA thrombolysis reported in the literature so far. Indications for rt-PA thrombolysis were stroke (n = 10), thrombosis of cardiac valve prosthesis (n = 7), pulmonary embolism (n = 7), deep venous thrombosis (n = 3), and myocardial infarction (n = 1). Remarkably, all thrombosis of cardiac valve prostheses occurred after switching from warfarin to heparin in order to prevent teratogenicity and fetal loss. Two patients died (7%) and three suffered from complications that were managed conservatively (11%). In another three patients thrombolysis was not successful. Thrombolysis complication rates were similar compared to non-pregnant patients for the above mentioned indications. Six out of the 26 fetus from surviving mothers died (23%), three of them after induced abortion for maternal reasons (12%). A likely causal relation to the prior thrombolysis could only be established in two fetal fatalities (8%). None of the live born children suffered a permanent deficit. Considering that rt-PA does not cross the placenta and taking into account that the complication rates do not exceed those of large randomised controlled trials thrombolytic therapy should not be withheld in pregnant patients in case of life-threatening or potentially debilitating thrombembolic disease.

IL-13 induces disease-promoting type 2 cytokines, alternatively activated macrophages and allergic inflammation during pulmonary infection of mice with Cryptococcus neoformans.

Abstract: In the murine model of Cryptococcus neoformans infection Th1 (IL-12/IFN-gamma) and Th17 (IL-23/IL-17) responses are associated with protection, whereas an IL-4-dependent Th2 response exacerbates disease. To investigate the role of the Th2 cytokine IL-13 during pulmonary infection with C. neoformans, IL-13-overexpressing transgenic (IL-13Tg(+)), IL-13-deficient (IL-13(-/-)), and wild-type (WT) mice were infected intranasally. Susceptibility to C. neoformans infection was found when IL-13 was induced in WT mice or overproduced in IL-13Tg(+) mice. Infected IL-13Tg(+) mice had a reduced survival time and higher pulmonary fungal load as compared with WT mice. In contrast, infected IL-13(-/-) mice were resistant and 89% of these mice survived the entire period of the experiment. Ag-specific production of IL-13 by susceptible WT and IL-13Tg(+) mice was associated with a significant type 2 cytokine shift but only minor changes in IFN-gamma production. Consistent with enhanced type 2 cytokine production, high levels of serum IgE and low ratios of serum IgG2a/IgG1 were detected in susceptible WT and IL-13Tg(+) mice. Interestingly, expression of IL-13 by susceptible WT and IL-13Tg(+) mice was associated with reduced IL-17 production. IL-13 was found to induce formation of alternatively activated macrophages expressing arginase-1, macrophage mannose receptor (CD206), and YM1. In addition, IL-13 production led to lung eosinophilia, goblet cell metaplasia and elevated mucus production, and enhanced airway hyperreactivity. This indicates that IL-13 contributes to fatal allergic inflammation during C. neoformans infection.