ABSTRACT
BackgroundIn December 2019, pneumonia infected with a novel coronavirus burst in Wuhan, China. Now the situation is almost controlled in China but is worse outside China. We aimed to build a mathematical model to capture the global trend of epidemics outside China. MethodsIn this retrospective, outside-China diagnosis number reported from Jan 21 to Feb 28, 2020 was downloaded from WHO website. We develop a simple regression model on these numbers: O_FD O_INLINEFIG[Formula 1]C_INLINEFIGM_FD(1)C_FD where Nt is the total diagnosed patient till the ith day, t=1 at Feb 1. FindingsBased on this model, we estimate that there have been about 34 unobserved founder patients at the beginning of spread outside China. The global trend is approximately exponential, with the rate of 10 folds every 19 days. Research in contextO_ST_ABSEvidence before this studyC_ST_ABSIn December 2019, pneumonia infected with a novel coronavirus burst in Wuhan, China. Now the situation is almost controlled in China but is worse outside China. Now there are 4,691 patients across 51 countries and territories outside China. We searched PubMed and the China National Knowledge Infrastructure database for articles published up to Feb 28, 2020, using the keywords "COVID", "novel coronavirus", "2019-nCoV" or "2019 novel coronavirus". No published work about the global trend of epidemics outside China could be identified. Added value of this studyWe built a simple "log-plus" linear model to capture the global trend of epidemics outside China. We estimate that there have been about 34 unobserved founder patients at the beginning of spread outside China. The global trend is approximately exponential, with the rate of 10 folds every 19 days. Implications of all the available evidenceWith the limited number of data points and the complexity of the real situation, a straightforward model is expected to work better. Our model suggests that the COVID-19 disease follows an approximate exponential growth model stably at the very beginning. We predict that the number of confirmed patients outside China will increase ten folds in every 19 days without strong intervention by applying our model. Powerful actions on public health should be taken to combat this epidemic all over the world.
ABSTRACT
<p><b>OBJECTIVE</b>To compare the effects of oral treatment with tetrandrine (TD) and N-acetylcys-teine (NAC) separately or jointly on silica-exposed rats.</p><p><b>METHODS</b>40 sprague-Dawly (SD) rats were randomly divided into normal saline group, quartz group, TD treatment group (50 mg/kg), NAC treatment group (500 mg/kg) and combined treatment group (TD: 50 mg/kg + NAC: 500 mg/kg). Rats in normal saline group and other groups received intratracheal instillation of normal saline and quartz dust suspension respectively. Treatment groups were given TD, NAC separately or jointly via esophagus the next day after instillation, once a day and six times a week for 30 consecutive days. At the end of experiment, the pathological changes of lung tissues were evaluated by the methods of Foot, HE and Masson staining, the level of hydroxyproline (HYP), malondjalde-hyde (MDA), tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in lung tissues were measured by alkaline hydrolysis method, the barbituric acid method and enzyme-linked immunosorbent assay (ELISA) respectively.</p><p><b>RESULTS</b>Compared with the quartz group, lymph nodes/body coefficients in all treatment groups and lung/body coefficient in combined treatment group were significantly decreased (P < 0.05). Pathology results showed that the normal saline group demonstrated no obvious evidence of lung damage. The quartz group lungs silicotic lesions focused on II~III level, the TD treatment group was mainly with I level, the NAC treatment group was mainly with I~II level, and the combined treatment group only showed little silicotic nodule, no obvious fibrosis. HYP content in TD treatment group and combined treatment group were significantly lower than that in the quartz group (P < 0.05), while it showed no obvious change in NAC treatment group. MDA content in lung tissues of each treatment group (TD treatment group, NAC treatment group and combined treatment group) were 18.80 ± 2.94, 20.13 ± 4.01 and 17.05 ± 3.52 nmol/ml respectively, which lower than in the quartz group (23.99 ± 3.26 nmol/ml). The level of IL-6 in lung tissues of the quartz group were 89.57 ± 8.78 pg/ml. After TD and NAC monotherapy, the IL-6 content decreased to 79.22 ± 9.65 pg/ml and 81.63 ± 5.72 pg/ml, and it decreased more significantly after combined medication (74.37 ± 3.17 pg/ml). The level of TNF-α in the quartz group were 59.05 ± 4.48 pg/ml. After TD and NAC monotherapy, the TNF-α content decreased to 50.48 ± 2.76 pg/ml and 54.28 ± 4.30 pg/ml, and it decreased more significantly after combined medication (49.10 ± 4.98 pg/ml).</p><p><b>CONCLUSION</b>NAC and TD could reduce MDA, TNF-α and IL-6 levels in lung tissue, and alleviate SiO2-induced pulmonary fibrosis in rats. Combined treatment with TD and NAC was more effective than TD or NAC treatment separately.</p>
