Comparison of Scientific Publications from Three Different Clinical Disciplines of German Universities

BACKGROUND

 Scientific publications are important for the advancement in medicine. Surgical disciplines including cardiac surgery are frequently considered not scientifically leading. However, a specific comparison between surgical and nonsurgical disciplines has not yet been performed. We thus compared scientific output of German departments of cardiac surgery with nonsurgical cardiology departments and surgical departments not addressing the heart (general surgery) of 34 universities in Germany.

METHODS

 For each university, the personnel working at the different departments were identified on the internet homepage in 2014. We searched for publications of these persons in 2011 to 2013 on PubMed, identified author position, coauthors, and type of article, as well as journal impact factor (JIF).

RESULTS

 There were 931 academic persons in cardiac surgery, 1,486 in general surgery, and 1,814 in cardiology with 12,096 publications related to these persons on PubMed. Cardiology published most manuscripts, including manuscripts from research conducted (first author), initiated (senior author), or both. Cardiac surgery had the least publications and had fewer authors from other departments or institutions. The average JIF was higher in cardiology compared with the two surgical disciplines. However, relating the number of publications to the number of employees in the departments, the differences were no longer apparent.

CONCLUSION

 We conclude that the number of publications in German universities appears to be a function of the number of academic personnel and not of the discipline. The lower JIFs in surgery may be due to the smaller surgical fields and/or due to less high impact interdisciplinary/interinstitutional publications in surgery.

Increased Protein Tyrosine Phosphatase 1B (PTP1B) Activity and Cardiac Insulin Resistance Precede Mitochondrial and Contractile Dysfunction in Pressure-Overloaded Hearts

BACKGROUND

Insulin resistance in diabetes mellitus has been associated with mitochondrial dysfunction. Defects at the level of mitochondria are also characteristic of heart failure. We assessed changes in cardiac insulin response and mitochondrial function in a model of pressure overload-induced heart failure.

METHODS AND RESULTS

Rats underwent aortic banding to induce pressure overload. At 10 weeks, rats showed cardiac hypertrophy and pulmonary congestion, but left ventricular dilatation and systolic dysfunction were only evident after 20 weeks. This contractile impairment was accompanied by mitochondrial dysfunction as shown by markedly reduced state 3 respiration of isolated mitochondria. Aortic banding did not affect systemic insulin response. However, insulin-stimulated cardiac glucose uptake and glucose oxidation were significantly diminished at 10 and 20 weeks, which indicates cardiac insulin resistance starting before the onset of mitochondrial and contractile dysfunction. The impaired cardiac insulin action was related to a decrease in insulin-stimulated phosphorylation of insulin receptor β. Consistently, we found elevated activity of protein tyrosine phosphatase 1B (PTP1B) at 10 and 20 weeks, which may blunt insulin action by dephosphorylating insulin receptor β. PTP1B activity was also significantly increased in left ventricular samples of patients with systolic dysfunction undergoing aortic valve replacement because of aortic stenosis.

CONCLUSIONS

Pressure overload causes cardiac insulin resistance that precedes and accompanies mitochondrial and systolic dysfunction. Activation of PTP1B in the heart is associated with heart failure in both rats and humans and may account for cardiac insulin resistance. PTP1B may be a potential target to modulate insulin sensitivity and contractile function in the failing heart.

Titania supported on silica as an efficient catalyst for deep oxidative desulfurization of a model fuel with exceptionally diluted H2O2

The continuous ODS of a model fuel, catalyzed by titanium nanocrystals dispersed onto silica, was performed with <1% aqueous H₂O₂.

Heart and Mitochondria: Pathophysiology and Implications for Cardiac Surgeons

Excluding the heart from systemic circulation during cardiac surgery renders the myocardium ischemic, resulting in cardiac damage. In addition, another hit to the myocardium will occur upon restoration of blood flow, in the reperfusion phase. Experimental data from animal models have revealed that loss of cardiac metabolic flexibility and mitochondrial dysfunctions contributes to contractile impairment in hypertrophied, failing, obese, and diabetic hearts. Such diseased hearts are prone to myocardial ischemia-reperfusion (I/R) injury. Although analyses in human cardiac samples are not as comprehensive as animal data, similar disease-associated metabolic and mitochondrial changes exist. Considering increasing age and comorbidities in patients nowadays, it is not surprising that I/R injuries remain a major cause of morbidity and mortality after cardiac surgery. Mitochondria have emerged as critical targets but also key regulators of myocardial I/R injury, and the extent of mitochondrial damage is a major determinant of myocardial I/R injury. Although cardioprotective mechanisms are diverse, many come together and involve steps at the point of mitochondria. We will, therefore, provide a description of mitochondrial alterations observed in various cardiac disease states and discuss the current experimental knowledge of the role of mitochondria in I/R and of potential protective mechanisms against myocardial I/R injury involving mitochondria. Within this review, we will focus on the protection against I/R injury conferred by caloric restriction (CR) and by ischemic conditioning. Further research is needed to establish whether strategies targeting mitochondria, which have been proposed from preclinical studies, could be translated into cardioprotective therapies against I/R injury in patients.

Complexity of pathomechanisms leading to diastolic heart failure in diabetes mellitus - potential field for therapeutic interventions?

Advanced glycation end products (AGE) have been implicated in diabetes associated complications. They have been suggested as potential mediators in the progression of diabetic heart failure and as a potential target for treatment. Brunvand et al. now provided evidence in that the suggested causal relationship between AGE and diastolic myocardial dysfunction cannot be confirmed in children with type 1 diabetes. The early signs of diastolic myocardial impairment were associated with higher BMI, but not with HbA1c levels. Furthermore, higher serum levels of MG-H1 and increased arterial stiffness were not significantly associated with diastolic dysfunction. The lack of association argues against an essential role of AGEs. This sobering finding does not support the potential to treat diastolic dysfunction by reduction approaches AGE in type 1 diabetic patients. Further pathogenic mechanisms involved in diabetic cardiomyopathy, such as alterations of calcium metabolism, or remodeling of the extracellular matrix, and intramyocardial inflammation may be further promising therapeutic targets.

Metabolomic profiling in patients undergoing Off-Pump or On-Pump coronary artery bypass surgery

Background

Coronary artery bypass surgery can be performed without (Off-Pump) or with cardiopulmonary bypass (On-Pump). Extracorporeal circulation and cardioplegic arrest may cause alterations in the plasma metabolome. We assessed metabolomic changes in patients undergoing On-Pump or Off-Pump coronary artery bypass surgery.

Methods

We assessed five analyte classes (41 acylcarnitines, 14 amino acids, 92 glycerophospholipids, 15 sphingolipids, sugars, lactate) using a mass-spectrometry-based kit (Biocrates AbsoluteIDQ® p150) in paired arterial and coronary sinus blood obtained from 10 consecutive On-Pump and 10 Off-Pump patients. Cardioplegia for On-Pump was warm blood Calafiore. On-Pump outcomes were corrected for hemodilution through crystalloid priming.

Results

Demographic data were equal in both groups with normal ejection fraction, renal and liver function. Patients received 2.25 ± 0.64 bypass grafts. All postoperative courses were uneventful. Of 164 measured metabolites, only 13 (7.9%) were altered by cardiopulmonary bypass. We found more long-chain acylcarnitines Off-Pump and more short-chain acylcarnitines On-Pump. Glycerophospholipids showed lower concentrations On-Pump and arginine (as the only different amino acid) Off-Pump. Interestingly, plasma arginine (nitric oxide precursor) concentration at the end of surgery correlated inversely with postoperative vasopressor need (r = −0.7; p < 0.001). Assessing arterial/venous differences revealed phosphatidylcholine-production and acylcarnitine-consumption. These findings were unaffected by cardiopulmonary bypass, cardioplegia or temporary vessel occlusion during Off-Pump surgery.

Conclusions

Cardiopulmonary bypass and warm blood cardioplegia cause only minor changes to the metabolomic profile of patients undergoing coronary artery bypass surgery. The observed changes affected mainly acylcarnitines. In addition, there appears to be a relationship between arginine and vasopressor need after bypass surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-017-0518-1) contains supplementary material, which is available to authorized users.

Surgical access via right thoracotomy facilitates tricuspid valve surgery in sheep

In quadrupeds, the three-dimensional orientation of the heart with respect to the thorax is fundamentally different from that in humans. In this study, we assessed the best surgical approach to the tricuspid valve in sheep. Firstly, different surgical access sites to the tricuspid valve were tested in sheep cadavers, the anatomy was analyzed, and the optimal surgical approach to the tricuspid valve was determined. Secondly - along with cardiopulmonary bypass and cardioplegic arrest -the chosen approach was tested in six adult sheep in vivo. Anatomical analyses revealed that a left thoracotomy provided optimal access to the aorta and left heart. However, visualization of the right heart was significantly impaired. In contrast, a right thoracotomy provided good access to the right heart, but the ascending aorta was difficult to approach. Therefore, in the in vivo studies, arterial cannulation was performed through a carotid (n = 4) or femoral (n = 2) artery. In conclusion, a right-sided thoracotomy allows good visualization of all components of the tricuspid valve complex in sheep, but not of the ascending aorta. Consequently, peripheral vessels are preferred for arterial cannulation. This work may stimulate the investigation of pathomechanisms and/or novel treatment options for tricuspid valve pathologies.

Quantitative Non-canonical Amino Acid Tagging (QuaNCAT) Proteomics Identifies Distinct Patterns of Protein Synthesis Rapidly Induced by Hypertrophic Agents in Cardiomyocytes, Revealing New Aspects of Metabolic Remodeling

Cardiomyocytes undergo growth and remodeling in response to specific pathological or physiological conditions. In the former, myocardial growth is a risk factor for cardiac failure and faster protein synthesis is a major factor driving cardiomyocyte growth. Our goal was to quantify the rapid effects of different pro-hypertrophic stimuli on the synthesis of specific proteins in ARVC and to determine whether such effects are caused by alterations on mRNA abundance or the translation of specific mRNAs. Cardiomyocytes have very low rates of protein synthesis, posing a challenging problem in terms of studying changes in the synthesis of specific proteins, which also applies to other nondividing primary cells. To study the rates of accumulation of specific proteins in these cells, we developed an optimized version of the Quantitative Noncanonical Amino acid Tagging LC/MS proteomic method to label and selectively enrich newly synthesized proteins in these primary cells while eliminating the suppressive effects of pre-existing and highly abundant nonisotope-tagged polypeptides. Our data revealed that a classical pathologic (phenylephrine; PE) and the recently identified insulin stimulus that also contributes to the development of pathological cardiac hypertrophy (insulin), both increased the synthesis of proteins involved in, e.g. glycolysis, the Krebs cycle and beta-oxidation, and sarcomeric components. However, insulin increased synthesis of many metabolic enzymes to a greater extent than PE. Using a novel validation method, we confirmed that synthesis of selected candidates is indeed up-regulated by PE and insulin. Synthesis of all proteins studied was up-regulated by signaling through mammalian target of rapamycin complex 1 without changes in their mRNA levels, showing the key importance of translational control in the rapid effects of hypertrophic stimuli. Expression of PKM2 was up-regulated in rat hearts following TAC. This isoform possesses specific regulatory properties, so this finding indicates it may be involved in metabolic remodeling and also serve as a novel candidate biomarker. Levels of translation factor eEF1 also increased during TAC, likely contributing to faster cell mass accumulation. Interestingly those two candidates were not up-regulated in pregnancy or exercise induced CH, indicating PKM2 and eEF1 were pathological CH specific markers. We anticipate that the methodologies described here will be valuable for other researchers studying protein synthesis in primary cells.