Publications by authors named "Christian GroSSe-Siestrup"

Exposure to radiofrequency (RF) power deposition during magnetic resonance imaging (MRI) induces elevated body-tissue temperatures and may cause changes in heart and breathing rates, disturbing thermoregulation. Eleven temperature sensors were placed in muscle tissue and one sensor in the rectum (measured in 10 cm depth) of 20 free-breathing anesthetized pigs to verify temperature curves during RF exposure. Tissue temperatures and heart and breathing rates were measured before, during, and after RF exposure.

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The use of portable media has become an integral part of our increasingly mobile society. The use of digital audio books is also growing steadily in Germany. The connection between the psychological effect of music of different volumes and rhythms and the change in reaction in road traffic with a corresponding increase in risk behavior, especially when driving, has already been proven in previous studies.

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This study assesses the biocompatibility of novel silk protein membranes with and without modification, and evaluates their effect on facilitating bone formation and defect repair in guided bone regeneration. Two calvarian bone defects 12 mm in diameter were created in each of a total of 38 rabbits. Four different types of membranes, (silk-, hydroxyapatite-modified silk-, β-TCP-modified silk- and commonly clinically used collagen-membranes) were implanted to cover one of the two defects in each animal.

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Exit-site infections remain one of the main complications for percutaneous devices, such as catheters for peritoneal dialysis or drivelines for ventricular assist devices. Many efforts have been made to create a biological seal, yet without long-term success. This study investigates a new kind of percutaneous device which is coated with an extricable polymeric membrane.

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Clinical records show ever increasing functional times of rotary blood pumps implanted in patients. With longer functional time, the problem of driveline infection is becoming more urgent. No material or scaffold has been found, which allows a permanent and stable ingrowth of skin cells that would prevent (pathogenic) germs entering the body.

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Purpose: To represent a MRI-compatible perfusion-system for extracorporeal perfusion of vital organs which permits the realisation of realistic experiments in a MR scanner.

Material And Methods: We performed MR examinations of explanted porcine livers and MR-guided interventions in porcine livers. Explanted organs were hemo-perfused under physiological conditions during the experiments.

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Aim: To evaluate for the first time in an animal model the possibility of absolute regional quantification of renal medullary and cortical perfusion by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) using a blood pool contrast agent.

Material And Methods: A total of 18 adult female pigs (age, 16-22 weeks; body weight, 45-65 kg; no dietary restrictions) were investigated by DCE-MRI. Absolute renal blood flow (RBF) measured by an ultrasound transit time flow probe around the renal vein was used as the standard of reference.

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Introduction: Models of isolated and perfused lungs study pathophysiological phenomena of the airways, but are limited by restricted resemblance to the human situation, non-physiological perfusates or the need for the use of high numbers of laboratory animals. The present model was established to address these difficulties.

Objectives: Aim of the current study was the establishment of an animal model that uses slaughterhouse animals and closely resembles physiological conditions found in humans.

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Background: Models of isolated and perfused kidneys are used to study the effects of drugs, hazardous or toxic substances on renal functions. Since physiological and morphological parameters of small laboratory animal kidneys are difficult to compare to human renal parameters, porcine kidney perfusion models have been developed to simulate closer conditions to the human situation, but exact values of renal parameters for different collection and perfusion conditions have not been reported so far. If the organs could be used out of regular slaughtering processes animal experiments may be avoided.

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To study invasion of the human fungal pathogen Candida albicans, several infection models have been established. This study describes the successful establishment of an ex vivo haemoperfused liver as a model to study invasion of C. albicans.

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Isolated porcine kidneys are commonly used to study physiological and pathophysiological aspects of renal homeostasis but standardized evaluation procedures of renal function in this model do not exist so far. A double-logarithmical nomogram is established for filtration and reabsorption functions in isolated and hemoperfused porcine kidneys using different perfusion settings. Model validity was demonstrated by the levels of urine flow and sodium excretion showing expected alteration levels of lowering in the ADH-group and increasing in the furosemide-group of isolated kidneys.

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Cadmium (Cd) has been in industrial use for a long period of time. Its serious toxicity moved into scientific focus during the middle of the last century. In this review, we discuss historic and recent developments of toxicological and epidemiological questions, including exposition sources, resorption pathways and organ damage processes.

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Unlabelled: Both fluid management and renal replacement therapies play a fundamental role in the treatment of critically ill patients. In a recent in vitro study, we have shown specific interactions of different colloids and the hemocompatibility of hemofilters. The present study was performed to compare the five most common fluids for volume resuscitation, i.

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Existing liver perfusion models are largely limited by high degrees of ischemic and reperfusion injury and the lack of standardization. To establish a highly standardized perfusion model and minimize reperfusion injury, a porcine liver perfusion model was developed using an artificial heart pump (Buecherl Artificial Heart). This model is characterized by pneumatically driven and pressure controlled blood pumps with pulsating flow characteristics.

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Background: Apart from their standard applications, haemofiltration (HF) and plasmafiltration (PF) may provide helpful therapy for sepsis, multiple organ- and acute liver-failure. Some colloids cause either decreases or increases in blood cell agglomeration. We hypothesized that solutions which reduce cell aggregability may lead to both improved filter clearance and better haemocompatibility due to decreasing rates of clogged hollow fibres.

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Polidocanol is an effective sclerosing agent that consists of 95% hydroxypolyethoxydodecane and 5% ethyl alcohol and is known to have a low risk of complications. However, since the compound has been proposed for the local treatment of liver diseases, the potential for topical hepatic side effects should be examined. Therefore, the new model of normothermic-hemoperfused isolated porcine slaughterhouse livers was used to examine polidocanol-hepatotoxicity encompassing the advantages of slaughterhouse organs to reduce animal experiments and autologous blood as an optimal perfusate.

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Background: Due to the increasing need for kidney donors, transplantation from non-heart-beating donors (NHBD) is currently being practiced more extensively. As detailed studies on the reperfusion injury of these kidneys do not exist so far, a comparison of renal ischemia reperfusion injury scores immediately after organ explantation with injury scores after NHBD organ explantation with subsequent cold storage would be useful.

Methods: Non-stored kidneys were compared to a group of kidneys stored for 6.

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Reperfusion injuries after organ transplantation affect graft function and influence long-term graft survival. As hypothermic storage, which minimizes the extent of unspecific tissue injury after ischemia and reperfusion, is significantly influenced by the composition of preservation solutions, strategies to optimize the different components may lead to longer graft survival. In the present study the effects of the preservation solution B2 on early renal function and histopathological changes were compared to histidine-tryptophan-ketoglutarate solution (HTK, Bretschneider) in a model of isolated blood-perfused porcine kidneys.

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Background: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys.

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Mammalian models of isolated perfused kidneys provide an important tool to study pharmacological, toxicological, and physiological properties of drugs, hormones, and vasoactive substances. As organs from small laboratory animals are difficult to compare to human conditions, porcine and bovine kidneys permit better approaches to simulate human conditions. We developed an alternative model for pharmacological studies using isolated hemoperfused porcine kidneys from slaughterhouse animals to reduce laboratory animal experiments.

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Different models of isolated and perfused livers and precision cut liver slices have been developed for studies on liver toxicology the past years. As most of these models were limited by nonphysiologic settings, a new model of normothermic hemoperfused isolated porcine slaughterhouse livers to examine hepatotoxicity was established encompassing the advantages of slaughterhouse organs to reduce animal experiments and autologous blood as an optimal perfusate. As model compound, the analgesic substance diclofenac was used and the effects of this drug on organ function parameters were compared to an untreated control group.

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Background: The rapidly evolving field of transplantation research with a focus on ischemic and reperfusion injuries has gained importance since the methodology of organ preservation significantly limits graft survival. Numerous models of isolated perfused kidneys have been established in the past years but limitations such as organ size, perfusate and ethical standards have restricted a widespread research in this area.

Methods: A model of hemoperfused isolated porcine slaughterhouse kidneys was established which encompasses the advantages of autologous blood as optimal perfusate and a reduction of animal experiments.

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1. Renal postischaemic reperfusion injury constitutes a significant problem after kidney transplantation. The polysaccharide fucoidin improves postischaemic function in lamb hearts, presumably by blocking selectin-mediated leucocyte adhesion.

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Drug discovery and development consists of a series of processes starting with the demonstration of pharmacological effects in experimental cell and animal models and ending with drug safety and efficacy studies in patients. A main limitation is often the unacceptable level of toxicity with the liver as the primary target organ. Therefore, approaches to study hepatic toxicity in the early phase of drug discovery represent an important step towards rational drug development.

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