Application of a data-driven XGBoost model for the prediction of COVID-19 in the USA: a time-series study.

OBJECTIVE: The COVID-19 outbreak was first reported in Wuhan, China, and has been acknowledged as a pandemic due to its rapid spread worldwide. Predicting the trend of COVID-19 is of great significance for its prevention. A comparison between the autoregressive integrated moving average (ARIMA) model and the eXtreme Gradient Boosting (XGBoost) model was conducted to determine which was more accurate for anticipating the occurrence of COVID-19 in the USA. DESIGN: Time-series study. SETTING: The USA was the setting for this study. MAIN OUTCOME MEASURES: Three accuracy metrics, mean absolute error (MAE), root mean square error (RMSE) and mean absolute percentage error (MAPE), were applied to evaluate the performance of the two models. RESULTS: In our study, for the training set and the validation set, the MAE, RMSE and MAPE of the XGBoost model were less than those of the ARIMA model. CONCLUSIONS: The XGBoost model can help improve prediction of COVID-19 cases in the USA over the ARIMA model.

The correlation between temperature and the incidence of COVID-19 in four first-tier cities of China: a time series study.

The COVID-19 outbreak emerged in Wuhan, China, and was declared a global pandemic in March 2020. This study aimed to explore the association of daily mean temperature with the daily counts of COVID-19 cases in Beijing, Shanghai, Guangzhou, and Shenzhen, China. Data on daily confirmed cases of COVID-19 and daily mean temperatures were retrieved from the 4 first-tier cities in China. Distributed lag nonlinear models (DLNMs) were used to assess the association between daily mean temperature and the daily cases of COVID-19 during the study period. After controlling for the imported risk index and long-term trends, the distributed lag nonlinear model showed that there were nonlinear and lag relationships. The daily cumulative relative risk decreased for every 1.0 °C change in temperature in Shanghai, Guangzhou, and Shenzhen. However, the cumulative relative risk increased with a daily mean temperature below - 3 °C in Beijing and then decreased. Moreover, the delayed effects of lower temperatures mostly occurred within 6-7 days of exposure. There was a negative correlation between the cumulative relative risk of COVID-19 incidence and temperature, especially when the temperature was higher than - 3 °C. The conclusions from this paper will help government and health regulators in these cities take prevention and protection measures to address the COVID-19 crisis and the possible collapse of the health system in the future.

Spatiotemporal cluster analysis of COVID-19 and its relationship with environmental factors at the city level in mainland China.

This study sought to identify the spatial, temporal, and spatiotemporal clusters of COVID-19 cases in 366 cities in mainland China with the highest risks and to explore the possible influencing factors of imported risks and environmental factors on the spatiotemporal aggregation, which would be useful to the design and implementation of critical preventative measures. The retrospective analysis of temporal, spatial, and spatiotemporal clustering of COVID-19 during the period (January 15 to February 25, 2020) was based on Kulldorff's time-space scanning statistics using the discrete Poisson probability model, and then the logistic regression model was used to evaluate the impact of imported risk and environmental factors on spatiotemporal aggregation. We found that the spatial distribution of COVID-19 cases was nonrandom; the Moran's I value ranged from 0.017 to 0.453 (P < 0.001). One most likely cluster and three secondary likely clusters were discovered in spatial cluster analysis. The period from February 2 to February 9, 2020, was identified as the most likely cluster in the temporal cluster analysis. One most likely cluster and seven secondary likely clusters were discovered in spatiotemporal cluster analysis. Imported risk, humidity, and inhalable particulate matter PM2.5 had a significant impact on temporal and spatial accumulation, and temperature and PM10 had a low correlation with the spatiotemporal aggregation of COVID-19. The information is useful for health departments to develop a better prevention strategy and potentially increase the effectiveness of public health interventions.

Localization and translocation of RhoA protein in the human gastric cancer cell line SGC-7901.

AIM: To elucidate the localization of RhoA in gastric SGC-7901 cancer cells and its translocation by lysophosphatidic acid (LPA) and/or 8-chlorophenylthio-cAMP (CPT-cAMP). METHODS: Immunofluorescence microscopy was used to determine the localization of RhoA. Western blotting was used to detect both endogenous and exogenous RhoA in different cellular compartments (membrane, cytosol, nucleus) and the translocation of RhoA following treatment with LPA, CPT-cAMP, or CPT-cAMP + LPA. RESULTS: Immunofluorescence staining revealed endogenous RhoA to be localized in the membrane, the cytosol, and the nucleus, and its precise localization within the nucleus to be the nucleolus. Western blotting identified both endogenous and exogenous RhoA within different cellular compartments (membrane, cytosol, nucleus, nucleolus). After stimulation with LPA, the amount of RhoA within membrane and nuclear extracts increased, while it decreased in the cytosol fractions. After treatment with CPT-cAMP the amount of RhoA within the membrane and the nuclear extracts decreased, while it increased within the cytosol fraction. Treatment with a combination of both substances led to a decrease in RhoA in the membrane and the nucleus but to an increase in the cytosol. CONCLUSION: In SGC-7901 cells RhoA was found to be localized within the membrane, the cytosol, and the nucleus. Within the nucleus its precise localization could be demonstrated to be the nucleolus. Stimulation with LPA caused a translocation of RhoA from the cytosol towards the membrane and the nucleus; treatment with CPT-cAMP caused the opposite effect. Furthermore, pre-treatment with CPT-cAMP was found to block the effect of LPA.

[Preparation and characterization of anti-morphine antiserum].

OBJECTIVE: To prepare the holoantigens of morphine and morphine-6-succinyl, and to evaluate the efficacy of both of the haptens in eliciting immune responses and their effects on morphine withdrawal symptoms in male mice. METHODS: Morphine-6-succinyl was prepared using acid anhydride mixture, and conjugated, along with morphine, with Blue carrier in the presence of carbodi imide. Immunization of mice with both the holoantigens and Freund adjuvant was performed, followed by determination of the antibody titer in the mouse serum with competitive ELISA and morphine dependence evaluation. RESULTS: The titers of the antibodies exceeded 1:8 000 in the serum of mice immunized with both holoantigens, and morphine- 6-succinyl induced a higher titer that was maintained for a longer period. The inhibition rates of the antisera to morphine and morphine-6-auccinyl had both reached 50%, and increased in a dose-dependent manner. CONCLUSION: Both morphine carrier conjugates can elicit high-titer antibody response in mice and relieve morphine addiction.

[Effect of dead space loading on ventilation, respiratory muscle and exercise performance in chronic obstructive pulmonary disease].

OBJECTIVE: To evaluate the effect of dead space (V(D)) loading on ventilation and respiratory muscle function, to test a novel measurement of oxygen consumption of respiratory muscle, and to analyze the effect of oxygen consumption of respiratory muscle on exercise performance. METHODS: Twenty-six patients with moderate chronic obstructive pulmonary disease (COPD) and 29 age-matched healthy control subjects underwent 30 W or 55 W constant work (CW) exercise in a standard protocol and under 300 ml (46 cm in length) dead space loading. Pulmonary function test (PFT) was measured pre- and post-exercise both in the dead space loading and unloading. RESULTS: The addition of 300 ml V(D) did not significantly affect FVC, FEV(1), and FEV(1)/FVC in both COPD patients and the healthy controls at rest or after CW exercise. The values of FVC, FEV(1), and FEV(1)/FVC with V(D) loading in COPD were (3.03 +/- 0.15) L, (1.95 +/- 0.09) L and (64.9 +/- 2.5)%, respectively; after 55 W CW exercise, those values were (3.03 +/- 0.18) L, (2.00 +/- 0.13) L, and (66.3 +/- 3.2)%, respectively (P > 0.05). Minute ventilation (V.(E)) and oxygen uptake (V.O(2)) significantly went up with V(D) loading and dropped with unloading at rest and during exercise in every subject. The enhancement of V.O(2) under V(D) loading (DeltaV.O(2)) was not significantly different between COPD and the control at rest or during lower intensity CW (30 W) exercise. However, DeltaV.O(2) was significantly higher in COPD than in the control during moderate intensity CW (55 W) exercise [(272 +/- 24) ml/min vs (194 +/- 19) ml/min, P < 0.05]. CONCLUSIONS: Lengthening respiratory tube to 46 cm (300 ml dead space) combined with moderate constant work exercise does not worsen the airflow obstructive in COPD,or results in respiratory muscle fatigue both in the COPD patients and the healthy controls. The enhancement of V.O(2) under V(D) loading can be considered as oxygen consumption of respiratory muscle working for increased ventilation. An advantage of oxygen consumption in respiratory muscle during moderate intensity exercise in COPD implies that maintaining the balance of oxygen supplying to both respiratory and limb muscles might be the key point in performing moderate to heavy exercise.