Obesity and Cardiac Function - The Role of Caloric Excess and its Reversal

Effects of caloric overload before caloric restriction in the murine heart

The beneficial effects of caloric restriction (CR) against cardiac aging and for prevention of cardiovascular diseases are numerous. However, to our knowledge, there is no scientific evidence about how a high-calorie diet (HCD) background influences the mechanisms underlying CR in whole heart tissue (WHT) in experimental murine models. In the current study, CR-treated mice with different alimentary backgrounds were subjected to transthoracic echocardiographic measurements. WHT was then analyzed to determine cardiac energetics, telomerase activity, the expression of energy-sensing networks, tissue-specific adiponectin, and cardiac precursor/cardiac stem cell markers. Animals with a balanced diet consumption before CR presented marked cardiac remodeling with improved ejection fraction (EF) and fractional shortening (FS), enhanced OXPHOS complex I, III, and IV, and CKMT2 enzymatic activity. Mice fed an HCD before CR presented moderate changes in cardiac geometry with diminished EF and FS values, but improved OXPHOS complex IV and CKMT2 activity. Differences in cardiac remodeling, left ventricular systolic/diastolic performance, and mitochondrial energetics, found in the CR-treated mice with contrasting alimentary backgrounds, were corroborated by inconsistencies in the expression of mitochondrial-biogenesis-related markers and associated regulatory networks. In particular, disruption of eNOS and AMPK -PGC-1α-mTOR-related axes. The impact of a past habit of caloric overload on the effects of CR in the WHT is a scarcely explored subject that requires deeper study in combination with analyses of other tissues and organs at higher levels of organization within the organ system. Such research will eventually lead to the development of preventative and therapeutic strategies to promote health and longevity.

Tissue biomarkers of drug efficacy: case studies using a MALDI-MSI workflow

MALDI MS imaging (MALDI-MSI) offers a capability to not only evaluate the distribution, localization and metabolism of drugs within tissues but also allow correlative tissue measurement of the effect of the drug on biomolecules in the targeted pathway. Particularly for MALDI-MSI, lipid molecules are readily detectable within tissues. Case study examples are provided for two different drugs targeting the sphingosine-1-phosphate/ceramide nexus in tumor xenograft tissues. A workflow combining high-resolution MALDI-MSI with on-tissue confirmation of targeted compounds using a structural library and on-tissue enzymatic digestion strategy is described. Representative images of drug metabolite distribution that correlate to an increase or decrease in sphingosine-1-phosphate or ceramide species are provided.