161 research outputs found
Success Factors of Plant Engineering Projects
AbstractProjects in plant manufacturing business are characterized by low margins and high risks. The knowledge and support of success factors, i.e. influencing factors that explain the success of a project, provide a suitable lever for plant manufacturing companies to improve their competitiveness. However, plant manufacturing business has not been a major field of success factor research yet. This contribution aims to close this research gap. In an extensive literature review existing success factors of other research fields are collected. 490 factors were examined on their applicability for engineering projects in expert interviews and an online survey. After consolidation, 41 success factors could be identified. If plant manufacturers consider these factors in project design and planning, project and business success can be influenced in a positive way. Since success factor research has been subject of criticism recently, this contribution includes a critical discussion of success factor research, too
Systemic hypothermia increases PAI-1 expression and accelerates microvascular thrombus formation in endotoxemic mice
INTRODUCTION: Hypothermia during sepsis significantly impairs patient outcome in clinical practice. Severe sepsis is closely linked to activation of the coagulation system, resulting in microthrombosis and subsequent organ failure. Herein, we studied whether systemic hypothermia accelerates microvascular thrombus formation during lipopolysacharide (LPS)-induced endotoxemia in vivo, and characterized the low temperature-induced endothelial and platelet dysfunctions. METHODS: Ferric-chloride induced microvascular thrombus formation was analyzed in cremaster muscles of hypothermic endotoxemic mice. Flow cytometry, ELISA and immunohistochemistry were used to evaluate the effect of hypothermia on endothelial and platelet function. RESULTS: Control animals at 37°C revealed complete occlusion of arterioles and venules after 759 ± 115 s and 744 ± 112 s, respectively. Endotoxemia significantly (p < 0.05) accelerated arteriolar and venular occlusion in 37°C animals (255 ± 35 s and 238 ± 58 s, respectively). This was associated with an increase of circulating endothelial activation markers, agonist-induced platelet reactivity, and endothelial P-selectin and plasminogen activator inhibitor (PAI)-1 expression. Systemic hypothermia of 34°C revealed a slight but not significant reduction of arteriolar (224 ± 35 s) and venular (183 ± 35 s) occlusion times. Cooling of the endotoxemic animals to 31°C core body temperature, however, resulted in a further acceleration of microvascular thrombus formation, in particular in arterioles (127 ± 29 s, p < 0.05 versus 37°C endotoxemic animals). Of interest, hypothermia did not affect endothelial receptor expression and platelet reactivity, but increased endothelial PAI-1 expression and, in particular, soluble PAI-1 antigen (sPAI-Ag) plasma levels. CONCLUSION: LPS-induced endotoxemia accelerates microvascular thrombus formation in vivo, most probably by generalized endothelial activation and increased platelet reactivity. Systemic hypothermia further enhances microthrombosis in endotoxemia. This effect is associated with increased endothelial PAI-1 expression and sPAI-Ag in the systemic circulation rather than further endothelial activation or modulation of platelet reactivity
Multiple Doses of Erythropoietin Impair Liver Regeneration by Increasing TNF-α, the Bax to Bcl-xL Ratio and Apoptotic Cell Death
BACKGROUND: Liver resection and the use of small-for-size grafts are restricted by the necessity to provide a sufficient amount of functional liver mass. Only few promising strategies to maximize liver regeneration are available. Apart from its erythropoiesis-stimulating effect, erythropoietin (EPO) has meanwhile been recognized as mitogenic, tissue-protective, and anti-apoptotic pleiotropic cytokine. Thus, EPO may support regeneration of hepatic tissue. METHODOLOGY: Rats undergoing 68% hepatectomy received daily either high dose (5000 IU/kg bw i.v.) or low dose (500 IU/kg bw i.v.) recombinant human EPO or equal amounts of physiologic saline. Parameters of liver regeneration and hepatocellular apoptosis were assessed at 24 h, 48 h and 5 d after resection. In addition, red blood cell count, hematocrit and serum EPO levels as well as plasma concentrations of TNF-alpha and IL-6 were evaluated. Further, hepatic Bcl-x(L) and Bax protein expression were analyzed by Western blot. PRINCIPAL FINDINGS: Administration of EPO significantly reduced the expression of PCNA at 24 h followed by a significant decrease in restitution of liver mass at day 5 after partial hepatectomy. EPO increased TNF-alpha levels and shifted the Bcl-x(L) to Bax ratio towards the pro-apoptotic Bax resulting in significantly increased hepatocellular apoptosis. CONCLUSIONS: Multiple doses of EPO after partial hepatectomy increase hepatocellular apoptosis and impair liver regeneration in rats. Thus, careful consideration should be made in pre- and post-operative recombinant human EPO administration in the setting of liver resection and transplantation
Inhibitor of Apoptosis Proteins as Novel Targets in Inflammatory Processes
Objective: Inhibitor of apoptosis proteins (IAPs), such as X-linked or cellular IAP 1/2 (XIAP, cIAP1/2), are important regulators of apoptosis. IAP antagonists are currently under clinical investigation as anticancer agents. Interestingly, IAPs participate in the inflammation-associated TNF receptor signaling complex and regulate NFκB signaling. This raises the question about the role of IAPs in inflammation. Here, we investigated the anti-inflammatory potential of IAP inhibitors and the role of IAPs in inflammatory processes of endothelial cells.
Methods and Results: In mice, the small molecule IAP antagonist A-4.10099.1 (ABT) suppressed antigen-induced arthritis, leukocyte infiltration in concanavalin A-evoked liver injury, and leukocyte transmigration in the TNFα-activated cremaster muscle. In vitro, we observed an attenuation of leukocyte– endothelial cell interaction by downregulation of the intercellular adhesion molecule-1. ABT did not impair NFκB signaling but decreased the TNFα-induced activation of the TGF-β–activated kinase 1, p38, and c-Jun N-terminal kinase. These effects are based on the proteasomal degradation of cIAP1/2 accompanied by an altered ratio of the levels of membrane-localized TNF receptor-associated factors 2 and 5.
Conclusion: Our results reveal IAP antagonism as a profound anti-inflammatory principle in vivo and highlight IAPs as important regulators of inflammatory processes in endothelial cells
Hemispheric differences in the duration of focal onset seizures
OBJECTIVE To assess hemispheric differences in the duration of focal onset seizures and its association with clinical and demographic factors.
METHODS A retrospective analysis was performed on adult patients with drug-resistant unifocal epilepsy, who underwent intracranial EEG recording between 01/2006 and 06/2016. Seizure duration was determined based on the subdural and/or stereo-EEG (sEEG) recordings. Hemispheric differences in seizure duration were statistically evaluated with regard to clinical and demographic data. RESULTS In total, 69 patients and 654 focal onset seizures were included. The duration of seizures with left-hemispheric onset (n~=~297) was by trend longer (91.88~±~93.92~s) than of right-hemispheric seizures (n~=~357; 71.03~±~68.53~s; p~=~.193). Significant hemispheric differences in seizures duration were found in temporal lobe seizures (n~=~225; p~=~.013), especially those with automotor manifestation (n~=~156; p~=~.045). A prolonged duration was also found for left-hemispheric onset seizures with secondary generalized commencing during waking state (n~=~225; p~=~.034), but not during sleep. A similar hemispheric difference in seizure duration was found in female patients (p~=~.040), but not in men.
CONCLUSIONS Hemispheric differences in seizure duration were revealed with significantly longer durations in case of left-hemispheric seizure onset. The observed differences in seizure duration might result from brain asymmetry and add new aspects to the understanding of seizure propagation and termination
Angiogenesis in tissue engineering : Breathing life into constructed tissue substitutes
Long-term function of three-dimensional (3D) tissue constructs depends on adequate vascularization after implantation. Accordingly, research in tissue engineering has focused on the analysis of angiogenesis. For this purpose, 2 sophisticated in vivo models (the chorioallantoic membrane and the dorsal skinfold chamber) have recently been introduced in tissue engineering research, allowing a more detailed analysis of angiogenic dysfunction and engraftment failure. To achieve vascularization of tissue constructs, several approaches are currently under investigation. These include the modification of biomaterial properties of scaffolds and the stimulation of blood vessel development and maturation by different growth factors using slow-release devices through pre-encapsulated microspheres. Moreover, new microvascular networks in tissue substitutes can be engineered by using endothelial cells and stem cells or by creating arteriovenous shunt loops. Nonetheless, the currently used techniques are not sufficient to induce the rapid vascularization necessary for an adequate cellular oxygen supply. Thus, future directions of research should focus on the creation of microvascular networks within 3D tissue constructs in vitro before implantation or by co-stimulation of angiogenesis and parenchymal cell proliferation to engineer the vascularized tissue substitute in situ
Who seizes longest? Impact of clinical and demographic factors
Objective
To investigate the impact of clinical and demographic parameters on the duration of focal onset seizures with and without secondary generalization using precise duration measurements from intracranial electroencephalographic (iEEG) recordings.
Methods
Patients with unifocal epilepsy syndromes and iEEG recording were retrospectively identified from the database of the local epilepsy center (2006‐2016). Seizure duration was defined as time difference of iEEG seizure pattern onset and cessation. The seizure semiology was classified based on video recordings. Clinical and demographic data were extracted from patient reports.
Results
In total, 69 adults were included, and 654 focal onset seizures were analyzed. Focal to bilateral tonic‐clonic seizures (FBTCSs; 98/654) were significantly longer than focal seizures (FSs) without generalization (FS‐BTCs; 556/654, P < .001), and most FSs (545/654, 83.3%) terminated within 2 minutes. The duration of FSs was prolonged with increasing age of the patients (P = .003) and was significantly shortened (P < .001) by evolution into an FBTCS. FBTCSs with lateralizing semiologies like version (P = .015) and sign of four (P = .043) were associated with longer bilateral tonic‐clonic manifestations. Furthermore, FBTCSs with preceding aura, frontal origin, or onset during sleep were by trend shorter. Age (P < .001) and disease duration (P = .028) were essential for prediction of FS‐BTC duration, whereas the vigilance state (P = .085) was the main prediction factor for the duration of FBTCSs.
Significance
The identified modifiers of seizure duration are of great relevance for clinical risk evaluation, especially in the aging epilepsy patient suffering from temporal lobe epilepsy with secondary generalized seizures
Microcirculatory alterations in ischemia–reperfusion injury and sepsis: effects of activated protein C and thrombin inhibition
Experimental studies in ischemia–reperfusion and sepsis indicate that activated protein C (APC) has direct anti-inflammatory effects at a cellular level. In vivo, however, the mechanisms of action have not been characterized thus far. Intravital multifluorescence microscopy represents an elegant way of studying the effect of APC on endotoxin-induced leukocyte–endothelial-cell interaction and nutritive capillary perfusion failure. These studies have clarified that APC effectively reduces leukocyte rolling and leukocyte firm adhesion in systemic endotoxemia. Protection from leukocytic inflammation is probably mediated by a modulation of adhesion molecule expression on the surface of leukocytes and endothelial cells. Of interest, the action of APC and antithrombin in endotoxin-induced leukocyte–endothelial-cell interaction differs in that APC inhibits both rolling and subsequent firm adhesion, whereas antithrombin exclusively reduces the firm adhesion step. The biological significance of this differential regulation of inflammation remains unclear, since both proteins are capable of reducing sepsis-induced capillary perfusion failure. To elucidate whether the action of APC and antithrombin is mediated by inhibition of thrombin, the specific thrombin inhibitor hirudin has been examined in a sepsis microcirculation model. Strikingly, hirudin was not capable of protecting from sepsis-induced microcirculatory dysfunction, but induced a further increase of leukocyte–endothelial-cell interactions and aggravated capillary perfusion failure when compared with nontreated controls. Thus, the action of APC on the microcirculatory level in systemic endotoxemia is unlikely to be caused by a thrombin inhibition-associated anticoagulatory action
Effects on Bone and Muscle upon Treadmill Interval Training in Hypogonadal Male Rats
Testosterone deficiency in males is linked to various pathological conditions, including
muscle and bone loss. This study evaluated the potential of different training modalities to counteract
these losses in hypogonadal male rats. A total of 54 male Wistar rats underwent either castration
(ORX, n = 18) or sham castration (n = 18), with 18 castrated rats engaging in uphill, level, or downhill
interval treadmill training. Analyses were conducted at 4, 8, and 12 weeks postsurgery. Muscle force
of the soleus muscle, muscle tissue samples, and bone characteristics were analyzed. No significant
differences were observed in cortical bone characteristics. Castrated rats experienced decreased
trabecular bone mineral density compared to sham-operated rats. However, 12 weeks of training
increased trabecular bone mineral density, with no significant differences among groups. Muscle force
measurements revealed decreased tetanic force in castrated rats at week 12, while uphill and downhill
interval training restored force to sham group levels and led to muscle hypertrophy compared to
ORX animals. Linear regression analyses showed a positive correlation between bone biomechanical
characteristics and muscle force. The findings suggest that running exercise can prevent bone loss in
osteoporosis, with similar bone restoration effects observed across different training modalities
- …