As coronavirus disease 2019 (COVID-19) pandemic continues, an increasing number of countries and territories are adopting restrictive measures based on physical ("social") distancing, aimed at preventing human-to-human transmission and thereby limiting virus propagation. Nationwide lockdowns, encompassing mass quarantine under stay-at-home ordinances, have already been proven effective to contain the COVID-19 outbreak in some countries. Nevertheless, a prolonged homestay may also be associated with potential side effects, which may jeopardize people's health and thus must be recognized and mitigated in a way without violating local ordinances. Some of the most important undesirable consequences of prolonged homestay such as physical inactivity, weight gain, behavioral addiction disorders, insufficient sunlight exposure and social isolation will be critically addressed in this article, which also aims to provide some tentative recommendations for the alleviation of side effects.

Health risks and potential remedies during prolonged lockdowns for coronavirus disease 2019 (COVID-19).

Methionine is an aliphatic, sulfur-containing, essential amino acid, and a precursor of succinyl-CoA, homocysteine, cysteine, creatine, and carnitine. Recent research has demonstrated that methionine can regulate metabolic processes, the innate immune system, and digestive functioning in mammals. It also intervenes in lipid metabolism, activation of endogenous antioxidant enzymes such as methionine sulfoxide reductase A, and the biosynthesis of glutathione to counteract oxidative stress. In addition, methionine restriction prevents altered methionine/transmethylation metabolism, thereby decreasing DNA damage and carcinogenic processes and possibly preventing arterial, neuropsychiatric, and neurodegenerative diseases. This review focuses on the role of methionine in metabolism, oxidative stress, and related diseases.

The role of methionine on metabolism, oxidative stress, and diseases

Exopolysaccharides from probiotic bacteria and their health potential.

Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of probiotic supplementation to optimize the health, performance, and recovery of athletes. Based on the current available literature, the conclusions of the ISSN are as follows:

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International Society of Sports Nutrition Position Stand: Probiotics

Methionine restriction (MetR) extends lifespan across different species and exerts beneficial effects on metabolic health and inflammatory responses. In contrast, certain cancer cells exhibit methionine auxotrophy that can be exploited for therapeutic treatment, as decreasing dietary methionine selectively suppresses tumor growth. Thus, MetR represents an intervention that can extend lifespan with a complementary effect of delaying tumor growth. Beyond its function in protein synthesis, methionine feeds into complex metabolic pathways including the methionine cycle, the transsulfuration pathway, and polyamine biosynthesis. Manipulation of each of these branches extends lifespan; however, the interplay between MetR and these branches during regulation of lifespan is not well understood. In addition, a potential mechanism linking the activity of methionine metabolism and lifespan is regulation of production of the methyl donor S-adenosylmethionine, which, after transferring its methyl group, is converted to S-adenosylhomocysteine. Methylation regulates a wide range of processes, including those thought to be responsible for lifespan extension by MetR. Although the exact mechanisms of lifespan extension by MetR or methionine metabolism reprogramming are unknown, it may act via reducing the rate of translation, modifying gene expression, inducing a hormetic response, modulating autophagy, or inducing mitochondrial function, antioxidant defense, or other metabolic processes. Here, we review the mechanisms of lifespan extension by MetR and different branches of methionine metabolism in different species and the potential for exploiting the regulation of methyltransferases to delay aging.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/acel.13034

Methionine metabolism and methyltransferases in the regulation of aging and lifespan extension across species.

Probiotics confer immunological protection to the host through the regulation, stimulation, and modulation of immune responses. Researchers have shifted their attention to better understand the immunomodulatory effects of probiotics, which have the potential to prevent or alleviate certain pathologies for which proper medical treatment is as yet unavailable. It has been scientifically established that immune cells (T- and B-cells) mediate adaptive immunity and confer immunological protection by developing pathogen-specific memory. However, this review is intended to present the recent studies on immunomodulatory effects of probiotics. In the early section of this review, concepts of probiotics and common probiotic strains are focused on. On a priority basis, the immune system, along with mucosal immunity in the human body, is discussed in this study. It has been summarized that a number of species of Lactobacillus and Bifidobacterium exert vital roles in innate immunity by increasing the cytotoxicity of natural killer cells and phagocytosis of macrophages and mediate adaptive immunity by interacting with enterocytes and dendritic, Th1, Th2, and Treg cells. Finally, immunomodulatory effects of probiotics on proinflammatory and anti-inflammatory cytokine production in different animal models have been extensively reviewed in this paper. Therefore, isolating new probiotic strains and investigating their immunomodulatory effects on cytokine profiles in humans remain a topical issue.

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Immunomodulatory Effects of Probiotics on Cytokine Profiles

Serine prevented high-fat diet-induced oxidative stress by activating AMPK and epigenetically modulating the expression of glutathione synthesis-related genes.

Methionine restriction (MR) exerts many beneficial effects, such as increasing longevity, decreasing oxidative damage and alleviating inflammatory responses. Much attention has been recently focused on the effects of MR on metabolic health, especially lipid metabolism, since the increasing incidence of obesity, insulin resistance and type 2 diabetes causes a worldwide health problem. In general, MR is considered to increase de novo lipogenesis, lipolysis and fatty acid oxidation, with a result of reduced fat accumulation. However, different responses in lipid metabolism between adipose tissue and liver are declared. Therefore, in this review, we will focus on the changes of lipid metabolism responses to dietary MR. Moreover, the comparison of alterations of fat metabolism responses to dietary MR between adipose tissue and liver, and the comparison of changes between rodents and pigs is made to illustrate the tissue- and species-specific responses. In addition, the possible mechanisms that might be engaged in the regulation of MR diet on lipid metabolism are also discussed.

Methionine restriction on lipid metabolism and its possible mechanisms.

Background/aims Early weaning often causes gut dysfunction. Since serine alleviates oxidative stress and inflammatory response which are accompany with early weaning, we conducted the study to explore whether serine improves intestinal function in early-weaned piglets. Methods Twenty-eight weaned piglets (aged 21 d) were fed either a basal diet or a basal diet plus 0.2% serine. We determined the effects of dietary serine supplementation on intestinal morphology by hematoxylin and eosin staining, expression of tight junction proteins (TJPs) by immunoblotting and immunofluorescence, expression of inflammatory cytokines and apoptosis markers by RT-qPCR and the level of antioxidant enzymes with ELISA kits in early-weaned piglets. Results Serine supplementation increased daily body weight gain while decreasing diarrhea incidence. Both the jejunum and ileum of serine-supplemented piglets showed regularly arranged villi and microvilli. Moreover, dietary serine increased TJP expression, and alleviated apoptosis, inflammation, and oxidative stress in the intestine of early-weaned piglets. Conclusion Our findings suggest that serine has the potential for use as a feed additive to prevent gut dysfunction caused by weaning.

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Dan Wan

Papers

Immunomodulatory Effects of Probiotics on Cytokine Profiles

Serine prevented high-fat diet-induced oxidative stress by activating AMPK and epigenetically modulating the expression of glutathione synthesis-related genes.

Methionine restriction on lipid metabolism and its possible mechanisms.

Effects of Dietary Serine Supplementation on Intestinal Integrity, Inflammation and Oxidative Status in Early-Weaned Piglets

Serine prevents LPS-induced intestinal inflammation and barrier damage via p53-dependent glutathione synthesis and AMPK activation