Publications by authors named "Christian Siebert"

Groundwater inflow can be a significant source of nutrients for riverine ecosystems, which can affect eutrophication i.e., the elevated primary production and the corresponding accumulation of algal biomass.

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An inexorable depletion of groundwater occurs where groundwater abstraction exceeds the natural recharge, a typical state of (semi-)arid regions, which calls for sustainable management of groundwater resources. This study aims to assess the available storage and recharge rates on a national scale in time and space by modelling the natural recharge in combination with a method to evaluate changing groundwater volumes, which revealed measures to quantify the overdraft of the observed national groundwater resources in Jordan. Applying the combination of hydrological model and method to evaluate changing groundwater volumes, a climate-driven systematic decline of groundwater recharge was eliminated as responsible process, while overdraft leads to dropping groundwater tables.

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The infiltration of untreated wastewater into aquifers highly endangers the availability of fresh-water for human consumption in semi-arid areas. This growing problem of potable water scarcity urgently requires solutions for groundwater protection. Decision support systems for local wastewater treatments in settlements already exist.

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Article Synopsis
  • One patient's success with nonoperative orthopaedic treatment can vary due to individual differences beyond just their knee pain condition.
  • Factors such as mental health status, body mass index (BMI), tobacco use, and how they perceive pain all play a significant role in the treatment outcome.
  • Understanding these demographic and psychological aspects is crucial for better tailoring treatment approaches for different patients.
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Objective: For elite athletes to train and compete at peak performance levels, it is necessary to manage their pain efficiently and effectively. A recent consensus meeting on the management of pain in elite athletes concluded that there are many gaps in the current knowledge and that further information and research is required. This article presents the crystallization of these acknowledged gaps in knowledge.

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A meniscal injury should not automatically lead to surgery. Even in light of all the developments in arthroscopic surgery, non-operative management still has a place in the treatment algorithms for lesions around the knee. In this second publication of the German guidelines for meniscal surgery, the authors describe the various treatment possibilities, their indications and offer critical insight into the various therapeutic options.

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Pain is a common problem among elite athletes and is frequently associated with sport injury. Both pain and injury interfere with the performance of elite athletes. There are currently no evidence-based or consensus-based guidelines for the management of pain in elite athletes.

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The Dead Sea region has faced substantial environmental challenges in recent decades, including water resource scarcity, ~1m annual decreases in the water level, sinkhole development, ascending-brine freshwater pollution, and seismic disturbance risks. Natural processes are significantly affected by human interference as well as by climate change and tectonic developments over the long term. To get a deep understanding of processes and their interactions, innovative scientific approaches that integrate disciplinary research and education are required.

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Abundant microbial mats, recently discovered in underwater freshwater springs in the hypersaline Dead Sea, are mostly dominated by sulfur-oxidizing bacteria. We investigated the source of sulfide and the activity of these communities. Isotopic analysis of sulfide and sulfate in the spring water showed a fractionation of 39-50‰ indicative of active sulfate reduction.

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The overall aim of the this study, which was conducted within the framework of the multilateral IWRM project SUMAR, was to expand the scientific basement to quantify surface- and groundwater fluxes towards the hypersaline Dead Sea. The flux significance for the arid vicinity around the Dead Sea is decisive not only for a sustainable management in terms of water availability for future generations but also for the resilience of the unique ecosystems along its coast. Coping with different challenges interdisciplinary methods like (i) hydrogeochemical fingerprinting, (ii) satellite and airborne-based thermal remote sensing, (iii) direct measurement with gauging station in ephemeral wadis and a first multilateral gauging station at the river Jordan, (iv) hydro-bio-geochemical approach at submarine and shore springs along the Dead Sea and (v) hydro(geo)logical modelling contributed to the overall aim.

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[Does anesthesia harm children's brain?].

Anasthesiol Intensivmed Notfallmed Schmerzther

April 2013

Animal data, that could show a correlation between anesthetic exposure and longterm damage to the developing brain, have raised concern within the international anesthesiology community, but also in patients, parents and media. The evaluation of the available literature does not provide evidence for changes in routine anesthetic practice associated with the order, to establish evidence through increased basic and clinical research about the mechanisms and possible effects in humans.

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Due to its extreme salinity and high Mg concentration the Dead Sea is characterized by a very low density of cells most of which are Archaea. We discovered several underwater fresh to brackish water springs in the Dead Sea harboring dense microbial communities. We provide the first characterization of these communities, discuss their possible origin, hydrochemical environment, energetic resources and the putative biogeochemical pathways they are mediating.

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Reports regarding sport injuries frequently pertain to the knee. Although ligament and meniscus damage are the most common, cartilage injuries are of great interest. Even with the great variety of treatment modalities available, the healing of these cartilage injuries remains problematic.

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Background And Purpose: Symptomatic treatment of osteoarthritis of the knee with leeches is presently undergoing a renaissance. Previous studies have shown methodical weaknesses. In the present study patients were blinded regarding the treatment, and a control group was included to explore possible differences in various subjective clinical scores and intake of pain medication over time between leech therapy and placebo control.

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Introduction: Autologous bone graft is the golden standard for bone grafting, but little is known about the influence of various preservation techniques used during surgery immediately following harvest on the osseous structures and graft vitality. Several studies focussed on the optimal treatment of the bone during harvest and implantation, but only few examined the intraoperative storage conditions on the back table. The aim of our study was to examine the influence of various intraoperative preservation techniques on human cancellous bone at different points to optimize the storage during surgery.

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Introduction: Autologous bone graft is the gold standard for the filling of large osseous defects. Because of its limited supply and complications such as pain, bleeding or infection, the development of alternative bone substitutes has been the subject of several studies. In clinical practice, the most commonly used bone substitutes are calcium phosphates like hydroxyapatite or tricalcium phosphate.

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Bone morphogenetic protein-2 (BMP-2) is a well-known osteoinductive protein, which requires a carrier for local application. As an alternative to the previously described carriers, an in situ hardening, resorbable, and osteoconductive beta-tricalcium phosphate cement (TCP) is tested. Trepanation defects in the bovine distal femoral epiphysis are filled with a composite consisting of TCP and 200 microg rhBMP-2 per cm3 TCP, autologous bone graft, pure TCP, or left empty.

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Basic fibroblast growth factor is a well known osteostimulative protein. The effects of basic fibroblast growth factor are dose-dependent and, when used with a carrier, influenced by the release kinetics. Aim of our study was to determine the effects of a composite of basic fibroblast growth factor and a newly developed, in situ setting tricalcium phosphate (TCP) cement.

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Article Synopsis
  • The study aimed to improve the stability of cemented acetabular components in hip replacements using an amphiphilic bonder, which has not been successful with previous techniques.
  • In an experiment with 20 sheep, the treatment group that utilized the bonder showed a stable cement-bone interface, while the control group experienced implant dislodgment and reduced structural integrity.
  • The results indicate that using the bonder enhances implant stability, is biocompatible, and can potentially prolong the lifespan of cemented acetabular components without harming the critical subchondral bone.
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Epithelioid sarcoma is a rare and highly malignant soft tissue tumor that is commonly found in the extremities and rarely in the trunk area. This malignant tumor often mimics granuloma or nodular fasciitis, which causes a delay in establishing the diagnosis. This type of cancer has a high recurrence rate.

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Introduction: In the age of growth factors and gene therapy, the induction of cartilage healing remains an unsolved problem. Even in autologous grafting, one of the preferred methods of treatment for focal osteochondral lesions, chondral integration remains difficult. This study aims to define a possible positive influence of growth factor augmentation on the ingrowth of these transplants.

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Article Synopsis
  • The autologous bone graft is the gold standard for bone replacement, but its limited availability and related complications highlight the need for synthetic alternatives.
  • A new tricalcium phosphate cement was tested in sheep, showing that it was almost fully resorbed and effectively replaced by new bone within 12 weeks.
  • Results indicated that the cement was more effective in promoting bone growth compared to autologous bone grafts, suggesting its potential as a practical alternative for filling bone defects.
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The osteostimulative effect of the basic fibroblast growth factor is well known, but it is dose dependent, and release kinetic depends on interactions with the used carrier. The aim of our study was to determine the osteostimulative effect of a composite, consisting of an in situ setting tricalcium phosphate cement and basic fibroblast growth factor. A trepanation defect of 1.

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Purpose: With the help of molecular markers, it has become possible to quantify cartilage repair and degradation in joints. In this study, we attempt to determine whether or not molecular markers in synovial fluid can be helpful in defining the repair process following autologous chondrocyte implantation (ACI).

Type Of Study: As part of a prospective clinical pilot study, 17 patients were evaluated before, as well as 6 weeks, 3, 6, and 12 months after the ACI.

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The aim of the study was to determine bone-regenerative effects of an in situ setting tricalcium phosphate (TCP) cement combined with rhBMP-2 and to compare it with autologous bone graft. A trepanation defect of 1.5 mm in the femur diaphysis of Sprague-Dawley rats was filled with an in situ setting TCP cement combined with 0, 0.

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