Temperatur- und Perfusionsmanagement bei akuter Typ-A-Aortendissektion

Die chirurgische Versorgung der akuten Typ-A-Aortendissektion erfuhr in den letzten Jahrzehnten v. a. im Hinblick auf das Perfusions- und Temperaturmanagement eine ständige Entwicklung. Neurologische Komplikationen sind die Hauptursache der postoperativen Morbidität und Mortalität. Die Verwendung einer Herz-Lungen-Maschine, des Kreislaufstillstands in tiefer Hypothermie, die temporäre Unterbrechung der zerebralen Perfusion oder Hypoperfusion des Gehirns und die Manipulation an der Aorta können zu neurologischen Schäden führen. Der Kreislaufstillstand in tiefer Hypothermie ermöglicht Eingriffe an der thorakalen Aorta, die für die Sanierung einer akuten Dissektion notwendig sein können. Dies hat allerdings Limitationen: Einerseits ist die Eingriffszeit begrenzt, andererseits führt die tiefe Hypothermie selbst zu Schäden. Experimentelle und klinische Studien konnten zeigen, dass der Grad der Hypothermie einen Einfluss auf die Komplikationsrate hat. Auch über den Nutzen der retrograden Hirnperfusion besteht noch Uneinigkeit. Das Konzept des Kreislaufstillstands mit zusätzlicher Hirnperfusion, besonders wenn der Grad der Hypothermie entsprechend der erwarteten Kreislaufstillstandzeit angepasst wird, erwies sich als sichere Methode. Es ermöglicht komplexe Eingriffe an der Aorta bei geringen Komplikationsraten und wird zunehmend als Standardverfahren bei der Versorgung der akuten Typ-A-Dissektion angewandt.

Intestine-Specific Overexpression of Carboxylesterase 2c Protects Mice From Diet-Induced Liver Steatosis and Obesity

Murine hepatic carboxylesterase 2c (Ces2c) and the presumed human ortholog carboxylesterase 2 (CES2) have been implicated in the development of nonalcoholic fatty liver disease (NAFLD) in mice and obese humans. These studies demonstrated that Ces2c hydrolyzes triglycerides (TGs) in hepatocytes. Interestingly, Ces2c/CES2 is most abundantly expressed in the intestine, indicating a role of Ces2c/CES2 in intestinal TG metabolism. Here we show that Ces2c is an important enzyme in intestinal lipid metabolism in mice. Intestine-specific Ces2c overexpression (Ces2c^int) provoked increased fatty acid oxidation (FAO) in the small intestine accompanied by enhanced chylomicron clearance from the circulation. As a consequence, high-fat diet-fed Ces2c^int mice were resistant to excessive diet-induced weight gain and adipose tissue expansion. Notably, intestinal Ces2c overexpression increased hepatic insulin sensitivity and protected mice from NAFLD development. Although lipid absorption was not affected in Ces2c^int mice, fecal energy content was significantly increased. Mechanistically, we demonstrate that Ces2c is a potent neutral lipase, which efficiently hydrolyzes TGs and diglycerides (DGs) in the small intestine, thereby generating fatty acids (FAs) for FAO and monoglycerides (MGs) and DGs for potential re-esterification. Consequently, the increased availability of MGs and DGs for re-esterification and primordial apolipoprotein B₄₈ particle lipidation may increase chylomicron size, ultimately mediating more efficient chylomicron clearance from the circulation. Conclusion: This study suggests a critical role for Ces2c in intestinal lipid metabolism and highlights the importance of intestinal lipolysis to protect mice from the development of hepatic insulin resistance, NAFLD, and excessive diet-induced weight gain during metabolic stress.

Pharmacological inhibition of adipose triglyceride lipase corrects high-fat diet-induced insulin resistance and hepatosteatosis in mice

Elevated circulating fatty acids (FAs) contribute to the development of obesity-associated metabolic complications such as insulin resistance (IR) and non-alcoholic fatty liver disease (NAFLD). Hence, reducing adipose tissue lipolysis to diminish the mobilization of FAs and lower their respective plasma concentrations represents a potential treatment strategy to counteract obesity-associated disorders. Here we show that specific inhibition of adipose triglyceride lipase (Atgl) with the chemical inhibitor, Atglistatin, effectively reduces adipose tissue lipolysis, weight gain, IR and NAFLD in mice fed a high-fat diet. Importantly, even long-term treatment does not lead to lipid accumulation in ectopic tissues such as the skeletal muscle or heart. Thus, the severe cardiac steatosis and cardiomyopathy that is observed in genetic models of Atgl deficiency does not occur in Atglistatin-treated mice. Our data validate the pharmacological inhibition of Atgl as a potentially powerful therapeutic strategy to treat obesity and associated metabolic disorders.

The enzyme Atgl participates in the breakdown of lipids in adipose tissue. Here the authors show that pharmacological inhibition of Atgl reduces weight gain and improves metabolic health in mice fed a high-fat diet, without causing adverse effects in cardiac muscle associated with genetic depletion of Atgl.

Adipocyte STAT5 deficiency promotes adiposity and impairs lipid mobilisation in mice

AIMS/HYPOTHESIS

Dysfunction of lipid metabolism in white adipose tissue can substantially interfere with health and quality of life, for example in obesity and associated metabolic diseases. Therefore, it is important to characterise pathways that regulate lipid handling in adipocytes and determine how they affect metabolic homeostasis. Components of the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway are involved in adipocyte physiology and pathophysiology. However, the exact physiological importance of the STAT family member STAT5 in white adipose tissue is yet to be determined. Here, we aimed to delineate adipocyte STAT5 functions in the context of lipid metabolism in white adipose tissue.

METHODS

We generated an adipocyte specific knockout of Stat5 in mice using the Adipoq-Cre recombinase transgene followed by in vivo and in vitro biochemical and molecular studies.

RESULTS

Adipocyte-specific deletion of Stat5 resulted in increased adiposity, while insulin resistance and gluconeogenic capacity was decreased, indicating that glucose metabolism can be improved by interfering with adipose STAT5 function. Basal lipolysis and fasting-induced lipid mobilisation were diminished upon STAT5 deficiency, which coincided with reduced levels of the rate-limiting lipase of triacylglycerol hydrolysis, adipose triglyceride lipase (ATGL, encoded by Pnpla2) and its coactivator comparative gene identification 58 (CGI-58). In a mechanistic analysis, we identified a functional STAT5 response element within the Pnpla2 promoter, indicating that Pnpla2 is transcriptionally regulated by STAT5.

CONCLUSIONS/INTERPRETATION

Our findings reveal an essential role for STAT5 in maintaining lipid homeostasis in white adipose tissue and provide a rationale for future studies into the potential of STAT5 manipulation to improve outcomes in metabolic diseases.

Scaffold precoating with human autologous extracellular matrix for improved cell attachment in cardiovascular tissue engineering

Cell attachment to a scaffold is a precondition for the development of bioengineered valves and vascular substitutes. This attachment is generally facilitated by the use of precoating factors, but some can cause toxic or immunologic side effects. Autologous extracellular matrix (ECM) is used as a precoating factor in our study. Ascending aortic tissue was cultured to obtain human myofibroblasts. Autologous ECM was extracted from the same aortic tissue. Poly(glycolic acid) (PGA) scaffolds were precoated with autologous ECM, human serum, or poly-L-lysine; the control group was pretreated with phosphate buffered saline (PBS). Myofibroblasts were seeded onto each scaffold, and the cell attachment was assayed and compared. Compared with the control group, precoating with human serum, poly-L-lysine, and ECM increased number of attached cells by 24%, 53%, and 48%, respectively. Differences between precoating groups were significant (p < 0.01), except for ECM versus poly-L-lysine. Scanning electron microscopy also demonstrated the high degree of cell attachment to the PGA fibers on scaffolds precoated with ECM and poly-L-lysine. Precoating polymeric scaffold with autologous human extracellular matrix is a very effective method of improving cell attachment in cardiovascular tissue engineering without the potential risk of immunologic reactions.

Experience with postinfarction left ventricular free wall rupture

BACKGROUND

Postinfarction rupture of the left ventricle is a rare event in which approach is not clearly standardised and outcome after repair is unknown. Our experience with this pathology was reviewed to analyze methods of repair and assess outcome beyond the patient's hospitalisation.

METHODS

Five patients underwent surgical repair of a postinfarction ventricular rupture between 1990 and 1998. Electromechanical dissociation (3 patients) and sudden hypotension and bradycardia (2 patients) were clinical indicators of rupture. Four patients underwent repair with cardiopulmonary bypass and 1 patient without. Repair consisted of epicardial patching (2 patients), direct suture (1 patient), infarct-exclusion (1 patient), and debridement and patch closure (1 patient) of the rupture. Myocardial revascularization was performed in 3 patients and mitral valve repair in 1 patient.

RESULTS

A satisfactory hemodynamic state was restored and bleeding was controlled in all patients. Two patients died postoperatively and another patient died 4 months after hospital discharge as a result of cardiac failure and/or sepsis. The other 2 patients are alive and in excellent condition 6 and 30 months respectively after repair.

CONCLUSIONS

Postinfarction rupture of the left ventricle bears a high mortality, but survival with an excellent quality of life is possible after surgical repair.

Fibrin gel as a three dimensional matrix in cardiovascular tissue engineering

OBJECTIVE

In tissue engineering, three-dimensional biodegradable scaffolds are generally used as a basic structure for cell anchorage, cell proliferation and cell differentiation. The currently used biodegradable scaffolds in cardiovascular tissue engineering are potentially immunogenic, they show toxic degradation and inflammatory reactions. The aim of this study is to establish a new three-dimensional cell culture system within cells achieve uniform distribution and quick tissue development and with no toxic degradation or inflammatory reactions.

METHODS

Human aortic tissue is harvested from the ascending aorta in the operation room and worked up to pure human myofibroblasts cultures. These human myofibroblasts cultures are suspended in fibrinogen solution and seeded into 6-well culture plates for cell development for 4 weeks and supplemented with different concentrations of aprotinin. Hydroxyproline assay and histological studies were performed to evaluate the tissue development in these fibrin gel structures.

RESULTS

The light microscopy and the transmission electron microscopy studies for tissue development based on the three-dimensional fibrin gel structures showed homogenous cell growth and confluent collagen production. No toxic degradation or inflammatory reactions could be detected. Furthermore, fibrin gel myofibroblasts structures dissolved within 2 days in medium without aprotinin, but medium supplemented with higher concentration of aprotinin retained the three-dimensional structure and had a higher collagen content (P<0.005) and a better tissue development.

CONCLUSIONS

A three-dimensional fibrin gel structure can serve as a useful scaffold for tissue engineering with controlled degradation, excellent seeding effects and good tissue development.

Frequency of collateral blood flow in the infarct-related coronary artery in rupture of the ventricular septum after acute myocardial infarction

Patients with postinfarction ventricular septal rupture have poor residual or collateral blood flow in the infarct artery and do not benefit from ischemic preconditioning. This suggests that rupture of the ventricular septum occurs on an unprotected and unprepared myocardium.

Modified approach to close multiple apical ventricular septal defects

The fish-mouth incision of the left ventricular apex is the established incision to access and close apical ventricular septum defect. A long diagonal branch may render this incision dangerous. In such a case, we performed a more anterior incision on the left ventricle, and fashioned a patch to exclude the whole defective area.

[Emergency surgery for abdominal aortic aneurysm--could an endovascular methods be considered?]

AIMS

The endovascular repair of abdominal aortic aneurysms (AAA) is a minimally invasive method which can be performed without laparotomy, thoracotomy or cross-clamping. Little is known about the endovascular feasibility in patients with contained ruptures.

METHODS

Retrospective study on 31 patients (mean age 70 +/- 6 years, 27 men (87.1%) and 4 (12.9%) women), who were treated for a ruptured aortic aneurysm between January 1996 and July 1998.

RESULTS

17/31 (55%) patients were hemodynamically stable. 14 patients were in severe shock and two died preoperatively. The operative mortality (two just after entering the abdomen) was 17% (5/29 patients) due to irreversible shock. A graft repair was performed in 27 patients. Preoperative CT scan was available in 12/31 (39%) patients. An infrarenal neck was present in all patients (length: 19 +/- 9 mm, internal diameter: 23 +/- 5 mm). The internal diameter of the external iliac artery was 10 +/- 2 mm. Six patients has an additional aneurysm of the common iliac artery, none of them bilaterally. In one patient infrarenal kinking of more than 90 degrees was detected.

CONCLUSIONS

In regard to the morphology, endovascular treatment would have been feasible in the majority of the patients where CT was already performed. Moreover, hemodynamic situation would have allowed to assess feasibility with a CT and perform endovascular treatment in most of patients with symptomatic or ruptured AAA. In conclusion, hemodynamically stable patients with symptomatic or leaking AAA should be investigated for endovascular repair.