Where to Find Leucine in Food and How to Feed Elderly With Sarcopenia in Order to Counteract Loss of Muscle Mass: Practical Advice

The term sarcopenia refers to the loss of skeletal muscle mass and strength that generally occurs during aging. The interventions that have proved most effective in reducing the severity and preventing the worsening of sarcopenia include physical exercise, especially resistance, and the administration of dietary supplements in association with a targeted diet; nutritional intervention is the main therapeutic approach for elderly people, since they are very often sedentary (also due to possible disabilities). Among the various nutrients, high biological value proteins and leucine are of particular interest for their demonstrated effects on the health of skeletal muscle. The intake of food containing proteins and leucine during meals stimulates muscle protein synthesis. Lower blood levels of leucine were associated with lower values of the skeletal muscle index, grip strength and performance. The international guidelines recommended that a leucine intake of 3 g at three main meals together with 25-30 g of protein is the goal to be achieved to counteract loss of lean mass in elderly. Food composition databases rarely show the amounts of leucine contained in foods and therefore it becomes difficult to build a diet that follows these guidelines. A table was therefore created for the first time in the literature to collect all the foods richest in leucine, thanks to the union of the most important Italian food databases. Moreover, in order to implement a diet that follows the right recommendations, another tables shows nutritional composition of breakfast, lunch and dinner (that each provide 3 grams of leucine and 25 grams of protein) for seven days

Electron Transport Properties of Single-Molecule-Bearing Multiple Redox Levels Studied by EC-STM/STS

Multielectron systems as possible components of molecular electronics devices are attracting compelling experimental and theoretical interest. Here we studied by electrochemical scanning tunneling techniques (EC-STMicroscopy and EC-STSpectroscopy) the electron transport properties of a redox molecule endowed with two redox levels, namely, the hydroquinone/quinone (H2Q/Q) couple. By forming self-assembled monolayers on Au(111) of oligo-phenylene-vinylene (OPV) derivatized H2Q/Q moieties, we were able to explore the features of the tunneling current/overpotential relation in the EC-STS setup. The behavior of the tunneling current sheds light onto the mechanism of electron transport involving the redox levels of the H2Q/Q redox pair coupled to tip and substrate electrodes

Hydroquinone-Benzoquinone Redox Couple as a Versatile Element for Molecular Electronics

The possibility of controlling electron transport in a single molecule bridged between two metal electrodes represents the ultimate goal of molecular electronics. Molecular electronics aims also at introducing specific properties for the electron transport features both by controlling the structural details of the junction and by exploiting new chemical functionalities. Here we show that, in a molecular junction, where electrodes are represented by a gold substrate and the tip of a scanning tunneling microscope in electrochemical environment, the use of a single molecular species makes it possible to obtain different features for the tunneling current according to the structural details of the junction. In particular, molecules endowed with redox properties brought about by a hydroquinone/benzoquinone redox couple can show both transistor-like and negative differential resistance (NDR) effects. We discuss the mechanistic processes that might describe the different behavior in light of theories of electron transfer between metal electrodes and redox molecules. The results show, on the one hand, the great potential and flexibility that molecular electronics offer and, on the other hand, the need of controlling as much as possible the details of the tunneling junction in order to obtain reproducible results

Hydroquinone-Benzoquinone Redox Couple as a Versatile Element for Molecular Electronics

The possibility of controlling electron transport in a single molecule bridged between two metal electrodes represents the ultimate goal of molecular electronics. Molecular electronics aims also at introducing specific properties for the electron transport features both by controlling the structural details of the junction and by exploiting new chemical functionalities. Here we show that, in a molecular junction, where electrodes are represented by a gold substrate and the tip of a scanning tunneling microscope in electrochemical environment, the use of a single molecular species makes it possible to obtain different features for the tunneling current according to the structural details of the junction. In particular, molecules endowed with redox properties brought about by a hydroquinone/benzoquinone redox couple can show both transistor-like and negative differential resistance (NDR) effects. We discuss the mechanistic processes that might describe the different behavior in light of theories of electron transfer between metal electrodes and redox molecules. The results show, on the one hand, the great potential and flexibility that molecular electronics offer and, on the other hand, the need of controlling as much as possible the details of the tunneling junction in order to obtain reproducible results

An Electrochemical Scanning Tunneling Microscopy Study of 2-(6-Mercaptoalkyl)hydroquinone Molecules on Au(111)

The hydroquinone/benzoquinone redox couple involves the exchange of two electrons and two protons in its oxidation/reduction reaction in aqueous buffered solutions. In this work, we employed Electrochemical Scanning Tunneling Microscopy and Spectroscopy (EC-STM, EC-STS) to study the interfacial electron transfer properties of hydroquinone incorporated in a Self Assembled Monolayer on a Au(111) substrate. The exchange of electrons between the STM tip and the substrate is regulated by the redox levels of the sandwiched molecule and showed the presence of two regions of tunneling enhancement in the tunneling current/overvoltage relationship. The two regions can be attributed to the presence of two one-electron transfer processes whose equilibrium positions shift upon pH variations. This is the first time a redox molecule involving the exchange of both electrons and protons is studied by EC-STM and EC-STS. The hydroquinone/benzoquinone redox couple can be exploited to obtain an electrochemically or a pH gated transistor

Effects of n-3 EPA and DHA supplementation on fat free mass and physical performance in elderly. A systematic review and meta-analysis of randomized clinical trial

The most studied n-3 polyunsaturated fatty acids (n-3 PUFAs) are eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3), and their intake seem to have a positive effect on skeletal muscle. This systematic review and meta-analysis aims to investigate the effect of n-3 EPA and DHA supplementation on fat free mass, and on different indexes of physical performance in the elderly. Eligible studies included RCT studies that investigated EPA and DHA intervention. Random-effects models have been used in order to estimate pooled effect sizes, the mean differences, and 95 % CIs. Findings from 14 studies (n = 2220 participants) lasting from 6 to 144 weeks have been summarized in this article. The meta-analyzed mean differences for random effects showed that daily n-3 EPA + DHA supplementation (from 0.7 g to 3.36 g) decreases the time of Time Up and Go (TUG) test of −0.28 s (CI 95 %−0.43, −0.13;). No statistically significant effects on physical performance indicators, such as 4-meter Walking Test, Chair Rise Test and Handgrip Strength, have been found. The fat free mass follows an improvement trend of +0.30 kg (CI 95 % -0.39, 0.99) but not statistically significant. N-3 EPA + DHA supplementation could be a promising strategy in order to enhance muscle quality and prevent or treat frailty

Evidence of a positive link between consumption and supplementation of ascorbic acid and bone mineral density

In animal models it has been shown that ascorbic acid (AA) is an essential cofactor for the hydroxylation of proline in collagen synthesis. However, there are still no precise indications regarding the role of AA in maintaining bone health in humans, so the aim of this narrative review was to consider state of the art on correlation between bone mineral density (BMD), AA dietary intake and AA blood levels, and on the effectiveness of AA supplement in humans. This review included 25 eligible studies. Fifteen studies evaluated correlations between AA intake and BMD: eight studies demonstrated a positive correlation between AA dietary intake and BMD in 9664 menopausal women and one significant interaction between effects of AA intake and hormone therapy. These data were also confirmed starting from adolescence (14,566 subjects). Considering studies on AA blood concentration and BMD, there are four (337 patients) that confirm a positive correlation. Regarding studies on supplementation, there were six (2671 subjects), of which one was carried out with AA supplementation exclusively in 994 postmenopausal women with a daily average dose of 745 mg (average period: 12.4 years). BMD values were found to be approximately 3% higher in women who took supplements

Development of an HPLC-MS/MS Method for the Determination of Silybin in Human Plasma, Urine and Breast Tissue

Silybin is a flavonolignan extracted from Silybum marianum with chemopreventive activity against various cancers, including breast. This study was designed to develop an HPLC-MS/MS method for the determination of silybin in human plasma, urine and breast tissue in early breast cancer patients undergoing Siliphos® supplementation, an oral silybin-phosphatidylcholine complex. The determination of silybin was carried out by liquid–liquid extraction with methyl-tert-butyl ether (MTBE); total silybin concentration was determined by treating the samples with β–glucuronidase, while for the determination of free silybin, the hydrolytic step was omitted. Naringenin and naproxen were selected as internal standards. The detection of the analyte was carried out by mass spectrometry and by chromatography. The HPLC-MS/MS method was evaluated in terms of selectivity, linearity, limit of quantification, precision and accuracy, and carryover. The method proved to be selective, linear, precise and accurate for the determination of silybin. To the best of our knowledge, this presents the first analytical method with the capacity to quantify the major bioactive components of milk thistle in three different biological matrices with a lower limit of quantification of 0.5 ng/mL for plasma. Silybin phosphatidylcholine, taken orally, can deliver high blood concentrations of silybin, which selectively accumulates in breast tumor tissue