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This study demonstrates numerical alterations of
This study demonstrates numerical alterations of creatinine levels potentially reflecting ongoing or even higher myocardial contraction of the LAA after successful LAAC. Creatinine is the direct breakdown product of creatine in muscle, the key metabolite for energy supply during muscular and myocardial contraction respectively. [54] [55] Together with creatinine kinase (CK) the transfer of phosphate for synthesis of endothelin receptor antagonist triphosphate (ATP) from adenosine diphosphate (ADP) is guaranteed. [56]
The results of the present study show that especially the tyrosine/phenylalanine ratio has increased significantly at mid-term follow-up confirming studies that show increased levels of tyrosine and decreased levels of phenylalanine in males compared to females [57,58]. Furthermore, in response to physical exercise, gender-related differences in metabolic profiling were associated to the influence of sex hormones [[59], [60], [61], [62]]. Additionally, animal and human studies demonstrated that increasing amount of adipose tissue is associated with increased levels of BCAA, including valine [[63], [64], [65]]. Also the tyrosine/phenylalanine metabolism is altered with increasing age, which could be confirmed by the present study, where patients >77 years revealed a significantly higher ratio than younger patients [66]. Moreover, Patients with paroxysmal AF were associated with increased levels of tyrosine and phenylalanine after mid-term follow-up compared to patients with permanent or persistent AF. Potentially, this increase reflects an elevated excess of catecholamines, since tyrosine and phenylalanine are substrates of their biosynthesis. [47] However, metabolomic studies usually focus on global changes in AF, irrespective of AF subgroups. [15,[67], [68], [69]]. Epidemiological studies could demonstrate that kynurenine concentrations correlate with insulin resistance and diabetic retinopathy [[70], [71], [72]]. The present study reveals lower levels of kynurenine in non-diabetics compared to diabetics, whereas these non-diabetics revealed an even larger increase at mid-term follow-up. Furthermore, Fischer ratio decreases significantly more in diabetics as a result of a higher usage of BCAA. A higher consumption of BCAA in diabetes may reduce hyperglycemia, as well as the reduced liver function in diabetics may reduce BCAA synthesis, reflecting the measured reduction of the Fischer ratio after LAAC [[73], [74], [75]]. It was shown that patients with heart failure and lower kynurenine levels reveal a better outcome. [76] Furthermore, kynurenine was related to adverse cardiac remodeling in patients with primary hyperparathyroidism. [77] Also in chronic kidney disease (CKD) a significantly lower reduction of kynurenine/tryptophan ratio and significant increased level of kynurenine were found after LAAC, which is in line with previous studies in CKD patients [78] The present study demonstrates a reduced kynurenine/tryptophan ratio, whereas its clinical implications await further research. Furthermore, knockout mice for BCAA catabolism, including valine, were associated with developing heart failure. [36] Accordingly, increases of valine are accompanied by increases of pro-BNP after successful LACC, and vice versa. A potential trigger of heart failure development by valine may be speculated.
Conclusions
Study limitations
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Funding
Conflict of Interest
Acknowledgments
We thank U. Müller for his excellent technical assistance (Biocrates Life Sciences AG (Innsbruck, Austria)). Supported by the DZHK (Deutsches Zentrum für Herz- Kreislauf-Forschung - German Centre for Cardiovascular Research) and by the BMBF (German Ministry of Education and Research).
Introduction
Acetyl esters are important contributors to the full flavor and aroma of many fruits such as banana [1], strawberry [2], pineapple [3], melon [4] and apple [5]. Other fruits such as tomato and grapes normally lack volatile esters [[6], [7], [8]]. Volatile esters in fruits are generally derived from the metabolism of essential fatty and amino acids [9]. The corresponding aldehydes are key intermediates in this process and are formed by decarboxylation and deamination reactions. The volatile aldehydes are then reduced to the respective alcohols that in turn may undergo acylation reactions [10,11]. Thus, in banana fruit, L-Leu is a precursor for the production of 3-methylbutyl ester, a key volatile determining banana aroma and flavor properties [12]. In melons, L-Phe, L-Leu, L-Met and other essential amino acids are metabolized into dozens of volatiles often including volatile esters, imparting unique notes to melon aromas [4,[13], [14], [15]].