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  • In summary our data demonstrated

    2021-07-22

    In summary, our data demonstrated a biological function of cpt1a gene from large yellow croaker. In particular, we indicated the effects of fasting on free carnitine status, CPT1 kinetics, and cpt1a mRNA expression in liver of large yellow croaker. During short-term fasting, the fish liver may have a strong capacity for ensuring the optimal catalytic efficiency through regulating carnitine-dependent Km rather than gene transcription and enzyme avtivity. However, long-term starvation may have a negative effect of on CPT1 catalytic efficiency. Thus, duration of fasting should be carefully considered when using fasting as a technique to improve flesh texture.
    Acknowledgment This work was supported by National Natural Science Foundation of China (Grant No. 41606122), and Natural Science Foundation of Zhejiang Province (LY15C190009).
    Introduction Human immunodeficiency virus (HIV)-protease inhibitor (PI)-based highly active antiretroviral therapy (HAART) has reduced morbidity and mortality. However, PI-based HAART has been associated with a cluster of metabolic complications analogous to “the cardiometabolic syndrome” [1] including: peripheral lipoatrophy, visceral adiposity, hyperlipidemia, insulin resistance, hyperglycemia, and overt type 2 diabetes mellitus [2], [3]. The mechanisms responsible for these complications have only partially been elucidated [4], [5], [6], [7], [8], [9], [10]. HIV-PI-induced disruptions in fatty topoisomerase ii (FA) and lipid partitioning and sensing might contribute to these complications, so we examined whether FA transport and/or oxidation are altered in murine skeletal muscle cells exposed to clinically relevant HIV-PI combinations. Evidence supports the notion that, in addition to host, viral, and behavior factors, HIV-PI-based HAART contributes to dysregulated FA and lipid metabolism. HIV-PI-based HAART increases whole body lipolysis and lipid oxidation rates [11], [12], increases intramuscular lipid accumulation [12], impairs adipocyte metabolism [13], and alters glucose homeostasis [5]. In adipocytes and rodent models, the HIV-PI ritonavir (r) inhibited human adipocyte differentiation [13], decreased LPL-mediated clearance of VLDL-TG, and impaired FA uptake into adipose tissue [14]. In rodent primary hepatocytes exposed to different HIV-PIs, lipid metabolism gene expression was reduced, and FA synthesis gene expression was increased [15]. In HIV-infected people treated with PI-based HAART [5], exercise-stimulated FA oxidation was blunted. This was attributed to impaired free FA (FFA) mobilization from adipose tissue, and not to defects in skeletal muscle FA transport and/or mitochondrial oxidation [16]. However, skeletal muscle FA transport and oxidation were not directly measured in this study. In addition, HIV-PI-based HAART-associated insulin resistance enhanced intramuscular lipid accumulation, which would reduce whole body lipid and muscle FA oxidation [17]. In these human studies [5], [17], it was not possible to determine the separate effects of HIV-PI, other anti-HIV medications, or other HIV-associated factors on muscle FA transport and oxidation. Therefore, we hypothesized that HIV-PIs impair skeletal muscle FA transport and oxidation. To test the effects of HIV-PIs on FA partitioning and sensing, we exposed C2C12 murine skeletal muscle cells to currently used HIV-PIs (ritonavir (r), lopinavir (LPV), atazanavir (ATV), darunavir (DRV) in combination (LPV/r, ATV/r, DRV/r)), and quantified FA transport and oxidation. We found that combined HIV-PI exposure (rather than individual PIs) reduces skeletal muscle FA oxidation by inhibiting FA transport protein expression.
    Materials and methods
    Results
    Discussion These findings suggest that, along with other factors that dysregulate fatty acid and lipid metabolism in HIV-infected people [29], several of the currently prescribed ritonavir-boosted HIV-PIs directly impair the ability of skeletal muscle cells to transport, partition, and oxidize palmitate (i.e., fatty acids), especially if neutral lipids have accumulated in the muscle cells (intramyocellular lipid accumulation), as has been reported to occur in HIV-infected people with insulin resistance [12]. Cade et al. [16] and others have postulated that HIV-PIs impair skeletal muscle fatty acid oxidation, but to our knowledge, this is the first direct in vitro evidence that HIV-PIs impair skeletal muscle palmitate uptake and oxidation.