No abstract

The onset of skeletal muscle regeneration is characterized by proliferating myoblasts. Proliferating myoblasts have an increased energy demand and lactate exchange across the sarcolemma can be used to address this increased demand. Monocarboxylate transporters (MCTs) are involved in lactate transport across the sarcolemma and are known to be affected by various physiological stimuli. However, MCT expression at the onset of skeletal muscle regeneration has not been determined. The purpose of this study was to determine if skeletal muscle regeneration altered MCT expression in regenerating tibialis anterior (TA) muscle. Male C57/BL6 mice were randomly assigned to either a control (uninjured) or bupivacaine (injured) group. Three days post injection, the TA was extracted for determination of protein and gene expression. A 21% decrease in muscle mass to tibia length (2.4 ± 0.1 mg/mm vs. 1.9 ± 0.2 mg/mm, P < 0.02) was observed. IGF-1 and MyoD gene expression increased 5.0-fold (P < 0.05) and 3.5-fold (P < 0.05), respectively, 3 days post bupivacaine injection. MCT-1 protein was decreased 32% (P < 0.03); however, MCT-1 gene expression was not altered. There was no difference in MCT4 protein or gene expression. Lactate dehydrogenase (LDH)-A protein expression increased 71% (P < 0.0004). Protein levels of LDH-B and mitochondrial enzyme cytochrome C oxidase subunit decreased 3 days post bupivacaine injection. CD147 and PKC-θ protein increased 64% (P < 0.03) and 79% (P < 0.02), respectively. MCT1 but not MCT4 expression is altered at the onset of skeletal muscle regeneration possibly in an attempt to regulate lactate uptake and use by skeletal muscle cells.

Background and objectives High moisture content (MC) rough rice was dried using an industrial microwave (MW) operated at a frequency of 915 MHz, and the impacts of the drying on the rice physicochemical properties were investigated. The treatments were performed at MW power levels 5, 10, and 15 kW, treatment durations 4, 6, and 8 min and for rice at initial MC of 24% (w.b.) and bed thicknesses 5, 10, and 15 cm. Near infrared spectroscopy and a rapid visco‐analyzer were used to assess the milled rice protein content, surface lipid content (SLC), total color difference (TCD), and rice peak and final viscosities. Findings The effect of increasing MW specific energy was statistically significant for all of the responses studied. Increasing MW specific energy resulted in an increase in measured rice SLC, protein content, and final and peak viscosities. Responses increased to a maximum then decreased at specific energies over 800 kJ/kg‐grain. The opposite profile was true for TCD. The TCD decreased as a result of increasing MW specific energy to a trough at 533.33 kJ/kg‐grain then increased at specific energies over 600 kJ/kg‐grain. The effect of varying rice bed thicknesses was not statistically significant. Conclusions It is vital to select appropriate MW specific energy to maintain the rice physicochemical properties. Significance and novelty Using MW heating with a frequency at 915 MHz provides new avenues to scale up the MW heating technology for rice drying; this may allow rapid, one‐pass rice drying while maintaining important quality characteristics.

Background and objectives The 915 MHz industrial microwave has a great penetration depth relative to the 2.45 GHz microwave and holds the potential to achieve one‐pass drying of deeper rice beds within a short drying duration. The objective of this research is to determine the effect of microwave specific energy on the quality, functional, and physicochemical properties of different rice cultivars. Two rice cultivars were used: a medium grain cultivar (Titan) and a long grain hybrid cultivar (XL753) from two different locations (Burdette and Carlisle). Rice samples at harvest moisture content of 20% wet basis were dried using the 915 MHz industrial microwave at specific energies ranging from 360 to 720 kJ per kg of initial wet grain mass (kJ.[kg‐grain]‐1). Rice physicochemical and functional properties were analyzed. Findings Results indicate that specific energy had a significant effect (p‐value < 0.0001) on moisture removal and head rice yield. On average, increasing specific energy (drying duration 3–4 min, power 4–6 kW) resulted in increased moisture points removed from 2.5% to 7.3% and 3.7% to 7.5% for long grain hybrids and medium grain cultivars, respectively, while head rice yield decreased. Setback and final viscosities increased while peak viscosity decreased with increasing specific energies. Kernel surface lipid and protein content slightly decreased with increasing specific energies, although specific energy did not have a significant effect on these responses. Resistant starch content decreased with increasing specific energy for hybrid rice. Water and oil absorption capacities varied at different specific energies. The most desirable specific energy for moisture removal that maintains rice quality characteristics (relative to control samples) was 525 kJ.[kg‐grain]‐1. Conclusions The 915 MHz industrial microwave has the potential to achieve one‐pass drying of rice. A study of the best specific energy for drying different cultivars of rice using this technology is essential to meet the diverse industrial needs for rice drying. Significance and novelty This study provides science‐based information on the properties of different rice cultivars dried using the 915 MHz microwave and selection of desirable microwave parameters for rice drying. The technology has a great potential to transform the rice drying industry by decreasing rice drying duration, improving milling yield, and energy efficiency.

Obesity is a major public health concern and it is essential to identify effective treatments and preventative strategies to stop continued increases in obesity rates. The potential functional roles of the branched chain amino acid leucine make this amino acid an attractive candidate for the treatment and/or prevention of obesity. The objective of this study was to determine if long-term leucine supplementation could prevent the development of obesity and reduce the risk factors for chronic disease in rats fed a high-fat (60 % fat) diet. Male Sprague-Dawley rats (n = 30 per dietary treatment) were meal-fed (3 meals/day) either a control, low-fat diet (LF), control + leucine (LFL), high-fat (HF), or high-fat + leucine (HFL) for 42 days. On day 42, rats were sacrificed at 0, 30, or 90 min postprandial. Animals fed the HF and HFL diets had higher (P < 0.05) final body weights and weight gain compared to animals fed the LF and LFL diets. Leucine supplementation increased epididymal fat mass (P < 0.05) and decreased muscle mass (P < 0.05). There was no effect of leucine supplementation on postprandial glucose or insulin response. However, there was a significant effect (P < 0.05) of diet and time on free fatty acid concentrations. There was no effect of leucine on muscle markers of protein synthesis (4E-BP1, p70S6K) or energy metabolism (Akt, AMPK). Leucine supplementation decreased (P < 0.05) PGC1α expression and increased (P < 0.05) PPARγ expression in skeletal muscle. In conclusion, long-term leucine supplementation does not prevent weight gain, improve body composition, or improve glycemic control in rats fed a high-fat diet.