Dose-Dependent Effects of Radiation on Mitochondrial Morphology and Clonogenic Cell Survival in Human Microvascular Endothelial Cells.

To better understand radiation-induced organ dysfunction at both high and low doses, it is critical to understand how endothelial cells (ECs) respond to radiation. The impact of irradiation (IR) on ECs varies depending on the dose administered. High doses can directly damage ECs, leading to EC impairment. In contrast, the effects of low doses on ECs are subtle but more complex. Low doses in this study refer to radiation exposure levels that are below those that cause immediate and necrotic damage. Mitochondria are the primary cellular components affected by IR, and this study explored their role in determining the effect of radiation on microvascular endothelial cells. Human dermal microvascular ECs (HMEC-1) were exposed to varying IR doses ranging from 0.1 Gy to 8 Gy (~0.4 Gy/min) in the AFRRI 60-Cobalt facility. Results indicated that high doses led to a dose-dependent reduction in cell survival, which can be attributed to factors such as DNA damage, oxidative stress, cell senescence, and mitochondrial dysfunction. However, low doses induced a small but significant increase in cell survival, and this was achieved without detectable DNA damage, oxidative stress, cell senescence, or mitochondrial dysfunction in HMEC-1. Moreover, the mitochondrial morphology was assessed, revealing that all doses increased the percentage of elongated mitochondria, with low doses (0.25 Gy and 0.5 Gy) having a greater effect than high doses. However, only high doses caused an increase in mitochondrial fragmentation/swelling. The study further revealed that low doses induced mitochondrial elongation, likely via an increase in mitochondrial fusion protein 1 (Mfn1), while high doses caused mitochondrial fragmentation via a decrease in optic atrophy protein 1 (Opa1). In conclusion, the study suggests, for the first time, that changes in mitochondrial morphology are likely involved in the mechanism for the radiation dose-dependent effect on the survival of microvascular endothelial cells. This research, by delineating the specific mechanisms through which radiation affects endothelial cells, offers invaluable insights into the potential impact of radiation exposure on cardiovascular health.

L-citrulline prevents heat-induced mitochondrial dysfunction and cell injury through nitric oxide-mediated Drp1 inhibition in mouse C2C12 myoblasts.

Severe heat exposure causes mitochondrial fragmentation and dysfunction, which contribute to the pathogenesis of heat-related illness. L-citrulline is a naturally occurring amino acid and has been suggested to influence heat shock responses. This study aimed to test whether L-citrulline supplementation would preserve mitochondrial integrity and attenuate heat-induced skeletal muscle injury, and elucidate the underlying mechanisms. At 37°C, L-citrulline (2 mM) increased mitochondrial elongation in mouse C2C12 myoblasts, a process associated with a reduction in mitochondrial fission protein Drp1 levels. Mechanistic studies revealed that L-citrulline increased cellular nitric oxide (NO) levels, but not S-nitrosylation of Drp1. L-citrulline caused a decrease in phosphorylation of Drp1 at Ser 616 and an increase in phosphorylation of Drp1 at Ser 637, which resulted in a reduced mitochondrial localization of Drp1. L-NAME, a non-selective NO synthase inhibitor, abolished the increase in L-citrulline-induced NO levels and inhibited Drp1 phosphorylation changes and mitochondrial elongation, which indicates involvement of a NO-dependent pathway. Under 43°C heat stress conditions, L-citrulline prevented translocation of Drp1 to mitochondria, mitochondrial fragmentation and decreased membrane potential. Finally, L-citrulline pretreatment inhibited heat-induced reactive oxygen species (ROS) overproduction, caspase 3/7 activation, apoptotic cell death, and improved cell viability. NO inhibitor L-NAME abolished all the above protective effects of L-citrulline under heat stress. Our results suggest that L-citrulline prevents heat-induced mitochondrial dysfunction and cell injury through NO-mediated Drp1 inhibition in C2C12 myoblasts. L-citrulline may be an effective treatment for heat-related illnesses and other mitochondrial diseases.

Protective effects of dietary curcumin and astaxanthin against heat-induced ROS production and skeletal muscle injury in male and female C57BL/6J mice.

AIMS: This study aimed to: 1) investigate sex differences in heat-induced mitochondrial dysfunction, ROS production, and skeletal muscle injury in mice; 2) evaluate whether curcumin and astaxanthin, alone or together, would prevent those heat-induced changes. MAIN METHODS: Male and female C57BL/6J mice were treated with curcumin and astaxanthin for 10 days, then exposed to 39.5 °C heat for up to 3 h. Heat-induced hyperthermia, changes in mitochondrial morphology and function, and oxidative damage to skeletal muscle were evaluated. KEY FINDINGS: Although female mice had a slightly higher basal core body temperature (Tc) than male mice, peak Tc during heat exposure was significantly lower in females than in males. Heat increased ROS levels in skeletal muscle in both sexes; interestingly, the increases in ROS were greater in females than in males. Despite the above-mentioned differences, heat induced similar levels of mitochondrial fragmentation and membrane potential depolarization, caspase 3/7 activation, and injury in male and female skeletal muscle. Individual treatment of curcumin or astaxanthin did not affect basal and peak Tc but prevented heat-induced mitochondrial dysfunction, ROS increases, and apoptosis in a dose-dependent manner. Moreover, a low-dose combination of curcumin and astaxanthin, which individually showed no effect, reduced the heat-induced oxidative damage to skeletal muscle. SIGNIFICANCE: Both male and female mice can develop mitochondrial dysfunction and oxidative stress in skeletal muscle when exposed to heat stress. High doses of either curcumin or astaxanthin limit heat-induced skeletal muscle injury, but a low-dose combination of these ingredients may increase their efficacy.

Origin discrimination of defatted pork via trace elements profiling, stable isotope ratios analysis, and multivariate statistical techniques.

This study verified the origin of 346 defatted Korean and non-Korean pork samples via trace elements profiling, and C and N stable isotope ratios analysis. The analyzed elements were 6Li, 7Li, 10B, 11B, 51V, 50Cr, 52Cr, 53Cr, 55Mn, 58Ni, 60Ni, 59Co, 63Cu, 65Cu, 64Zn, 66Zn, 69Ga, 71Ga, 75As, 82Se, 84Sr, 86Sr, 87Sr, 88Sr, 85Rb, 94Mo, 95Mo, 97Mo, 107Ag, 109Ag, 110Cd, 111Cd, 113Cd, 112Cd, 114Cd, 116Cd, 133Cs, 206Pb, 207Pb, and 208Pb. Content (mg/kg) of 51V (0.012), 50Cr (0.882), 75As (0.017), 85Rb (57.7), and 87Sr (46.3) were high in Korean pork samples whereas 6Li, 7Li, 59Co, 55Mn, 58Ni, 84Sr, 86Sr, 88Sr, 111Cd, and 133Cs were found higher in non-Korean samples. The results of discriminant analysis showed that the trace elements content and stable isotope ratios were significant for the discrimination of geographical origins with a perfect discrimination rate of 100%.

Geographical origin authentication of pork using multi-element and multivariate data analyses.

In the recent years, consumers have become increasingly concerned about the authenticity and labeling claims associated with meat and meat based products. In this study, investigating geographical origin authenticity of pork, 323 samples of pork belly were collected from Korea, USA, Germany, Austria, Netherlands and Belgium. These were analyzed for twenty-nine macro and trace elements using inductively coupled plasma-optical emission spectroscopy (ICP-OES), and ICP-mass spectrometry (MS). The applied analytical techniques were validated by quality assurance parameters in which the values of correlation coefficient, limits of detection and quantification, precision, and spiking recovery confirmed that the methods were well efficient and in accordance to the criteria set by the Association of Official Analytical Chemists (AOAC) for metals analysis. From the results of multivariate analyses, it was found that the trace elements are promising constituents which could be used to accurately determine the inter-continental provenance of pork.

Determination of volatile organic compounds, catechins, caffeine and theanine in Jukro tea at three growth stages by chromatographic and spectrometric methods.

Tea contains characteristic volatile organic compounds, polyphenols, caffeine and catechins, and is therefore among the most widely consumed beverages all over the world. In this study, fresh Jukro tea leaves collected from Damyang-gun (Jeollanam-do) at 40, 60 and 90day growth stages, were semi-fermented. The volatile organic compounds (VOCs) were extracted by simultaneous distillation-solvent extraction (SDE) and analyzed by gas chromatography/mass spectrometry (GC/MS). Catechins, caffeine and theanine were analyzed by high performance liquid chromatography (HPLC). A total of 159 VOCs were identified in the analyzed Jukro tea leaves. Comparatively, the increase in the concentrations of VOCs was high in 60day leaves. The content of catechins increased along the three growth stages, whereas caffeine, compared to 90day leaves, was higher for 40 and 60day leaves. Based on the results, the 60day leaves were found to be the most suitable and useful for making semi-fermented Jukro tea.