A modeling study of the effect of social distancing policies on the early spread of coronavirus disease 2019: a case of South Korea.

The social distancing policy is an effective way to prevent the spread of infectious diseases in the initial phase of their outbreak when medical evidence to support a particular course of treatment is deficient. While studies on the coronavirus disease 2019 (COVID-19) have mainly focused on the effects of specific measures (e.g., school and workplace closures and restrictions on movement), few investigated the characteristics of epidemic trends in response to the intensity of the policy and the amount of time required for policy measures to take effect. This study employs the SIRD (susceptible, infected, recovered, and deceased) model to analyze the COVID-19 epidemic trend according to the intensity of the social distancing policy in South Korea. The model reveals that the reproduction number began at 5.58 and fluctuated between 0.14 and 1.72 during the study period in accordance with different policy intensities. At the beginning of the social distancing policy, restrictions on public facility use were likely to have been effective in preventing the spread of COVID-19. When the intervention was relaxed, the transmission potential increased significantly. According to the reproduction number, social distancing policies prove to be effective after 13-19 days of implementation; however, as the pandemic progressed, this period extended from 13-14 to 18-19 days for the same effect. This suggests that governments need to consider not only the intensity of the social distancing policy, but also people's low responsiveness as the pandemic remains prevalent over time. It is also recommended they take preemptive action to ensure sufficient time for the policy to achieve its stated goal.

Deer Velvet and Eleutherococcus senticosus Mixture Regulated Immune Function in C57BL/6N Mice with Immunosuppression Induced by Forced Swimming.

Immunosuppression occurs in response to a variety of external antigens. However, various immune cells and cytokines can activate the immune system. In this study, it was found that fermented deer velvet (FD) and fermented Eleutherococcus senticosus (FE) extract (FDE) mixtures regulated the immunity of animals that underwent induced immunosuppression through forced swimming exercise (FSE). Seven mouse treatment groups were included in the experiment: normal controls, FSE controls, positive controls (FSE+red ginseng 300 mg/kg body weight), FD200 (FSE+FD 200 mg/kg body weight), FE200 (FSE+FE 200 mg/kg body weight), FDE50 (FSE+FDE 50 mg/kg body weight), and FDE200 (FSE+FDE 200 mg/kg body weight). Oral intake of experimental and control substances lasted for 2 weeks. Oral FDE intake increased cell counts for major histocompatibility complex (MHC) I, MHC II, CD4(+) T cells, and CD8(+) T cells compared with controls. Moreover, FDE increased Th1 (interleukin [IL]-2 and interferon gamma) cytokine proliferation, T cell proliferation, IL-12 and IL-15 production, and natural killer cell activity compared with controls. In addition, FDE inhibited Th2 cytokines (IL-4, IL-6, IL-10, and tumor necrosis factor alpha) and nitric oxide production, increased B cell proliferation and leukocyte count, and promoted immunoglobulin A and G serum levels compared with controls. Thus, the finding that FDE increased immune function in an immunosuppression model suggests that FDE has immunomodulatory capacity.

Evaluating the Memory Enhancing Effects of Angelica gigas in Mouse Models of Mild Cognitive Impairments.

(1) Background: By 2050, it is estimated that 130 million people will be diagnosed with dementia, and currently approved medicines only slow the progression. So preventive intervention is important to treat dementia. Mild cognitive impairment is a condition characterized by some deterioration in cognitive function and increased risk of progressing to dementia. Therefore, the treatment of mild cognitive impairment (MCI) is a possible way to prevent dementia. Angelica gigas reduces neuroinflammation, improves circulation, and inhibits cholinesterase, which can be effective in the prevention of Alzheimer's disease and vascular dementia and the progression of mild cognitive impairment. (2) Methods: Angelica gigas (AG) extract 1 mg/kg was administered to mildly cognitive impaired mice, models based on mild traumatic brain injury and chronic mild stress. Then, spatial, working, and object recognition and fear memory were measured. (3) Result: Angelica gigas improved spatial learning, working memory, and suppressed fear memory in the mild traumatic brain injury model. It also improved spatial learning and suppressed cued fear memory in the chronic mild stress model animals. (4) Conclusions: Angelica gigas can improve cognitive symptoms in mild cognitive impairment model mice.

Age-Related Decrease in Stress Responsiveness and Proactive Coping in Male Mice.

Coping is a strategic approach to dealing with stressful situations. Those who use proactive coping strategies tend to accept changes and act before changes are expected. In contrast, those who use reactive coping are less flexible and more likely to act in response to changes. However, little research has assessed how coping style changes with age. This study investigated age-related changes in coping strategies and stress responsiveness and the influence of age on the processing of conditioned fear memory in 2-, 12- and 23-month-old male mice. Coping strategy was measured by comparing the escape latency in an active avoidance test and by comparing responses to a shock prod. The results showed that proactivity in coping response gradually decreased with age. Stress responsiveness, measured by stress-induced concentration of corticosterone, was also highest in 2-month-old mice and decreased with age. Consolidation of fear memory was highest in 12-month-old mice and was negatively correlated with the degree of stress responsiveness and proactivity in coping. Fear extinction did not differ among age groups and was not correlated with stress responsiveness or the proactivity of coping. However, the maintenance of extinct fear memory, which was best in 2-month-old mice and worst in 12-month-old mice, was negatively correlated with stress responsiveness but not with coping style. Age-dependent changes in the expression of glucocorticoid receptor (GR) and its regulatory co-chaperones, which are accepted mechanisms for stress hormone stimulation, were measured in the hippocampus. The expression of GR was increased at 12 months compared to other age groups. There were no differences in Hsp70 and BAG1 expression by age. These results can be summarized as follows: (1) stress responsiveness and proactivity in coping decreased with age class; (2) consolidation of fear memory was negatively correlated with both stress responsiveness and proactivity; however, maintenance of extinct fear memory was negatively correlated with stress responsiveness only; and (3) consolidation and maintenance of extinct fear memory appeared to be more influenced by factors other than stress reactivity and proactivity in coping, such as the amount of hippocampal glucocorticoid expression.