Assessing eco-geographic influences on COVID-19 transmission: a global analysis.

COVID-19 has been massively transmitted for almost 3 years, and its multiple variants have caused serious health problems and an economic crisis. Our goal was to identify the influencing factors that reduce the threshold of disease transmission and to analyze the epidemiological patterns of COVID-19. This study served as an early assessment of the epidemiological characteristics of COVID-19 using the MaxEnt species distribution algorithm using the maximum entropy model. The transmission of COVID-19 was evaluated based on human factors and environmental variables, including climate, terrain and vegetation, along with COVID-19 daily confirmed case location data. The results of the SDM model indicate that population density was the major factor influencing the spread of COVID-19. Altitude, land cover and climatic factor showed low impact. We identified a set of practical, high-resolution, multi-factor-based maximum entropy ecological niche risk prediction systems to assess the transmission risk of the COVID-19 epidemic globally. This study provided a comprehensive analysis of various factors influencing the transmission of COVID-19, incorporating both human and environmental variables. These findings emphasize the role of different types of influencing variables in disease transmission, which could have implications for global health regulations and preparedness strategies for future outbreaks.

[Relationship between Effect of Induction Chemotherapy and Prognosis in AML Patients].

OBJECTIVE: To explore the relationship between effect of induction chemotherapy and prognosis in acute myeloid leukemia (AML) patients. METHODS: The clinical data of 146 adult AML patients treated in Affiliated Hospital of Chifeng University from March 2015 to March 2018 were enrolled and retrospectively analyzed. Day 14 bone marrow biopsy (D14BM) cellularity and blast proportion, daily peripheral blood blast (PBB) clearance rate, time to PBB clearance and etc. were primarily observed after induction chemotherapy. All the patients were divided into Non-relapse survival group, Relapse survival group, Non-relapse death group and Relapse death group according to survival and recurrence situation during 2-year follow-up. The survival of the patients was analyzed by Kaplan-Meier. Univariate analysis of prognostic factors were performed by ordinal Logistic regression, and ROC curve was used to assess the prediction efficiency of those factors for the 2-year overall survival (OS) and relapse of the patients. RESULTS: A total of 138 patients were included since 8 cases failed to be assessed clinically. Their 2-year OS rate was 65.94%. Age of the patients in Non-relapse survival group was lower than that in Relapse death group. The D14BM cellularities in Non-relapse survival group and Relapse survival group were lower than those in Relapse death group (P<0.05). Daily PBB clearance rates in Non-relapse survival group and Relapse survival group were higher than those in Non-relapse death group and Relapse death group (P<0.05). There was a statistical difference among the four groups in the number of cycles of induction chemotherapy (P<0.05). The survival rate within 2 years in the patients with D14BM cellularity≤10% was higher than that in patients with cellularity >10%, while it was higher in patients with daily PBB clearance rate >20% than those with clearance rate≤20% (P<0.05). Age (HR=1.102, P=0.000), D14BM cellularity (HR=1.252, P=0.000) and the cycles of induction chemotherapy≥3 (HR=1.703, P=0.000) were the risk factors affecting the prognosis of AML patients, while daily PBB clearance rate was a protective factor (HR=0.799, P=0.000). The AUC of age, daily PBB clearance rate and D14BM cellularity in predicting 2-year OS of AML patients was 0.738, 0.817 and 0.807, respectively, whereas in predicting relapse within 2 years it was 0.691, 0.647 and 0.711, respectively. There was no statistical difference among the three factors in the sensitivity of 2-year OS (68.11%, 85.12%, 74.49%) and 2-year relapse (50.00%, 64.13%, 61.60%) (P>0.05). CONCLUSION: Bone marrow biopsy results and PBB clearance rate are related to prognosis in AML patients, which can offer certain predictive value in assessing 2-year OS of patients.

[Distribution of compact bone mesenchymal stem cells in lung tissue and bone marrow of mouse].

This study was aimed to investigate the distribution of compact bone mesenchymal stem cells(MSC) marked with lentiviral plasmid pGC FU-RFP-LV in lung tissue and bone marrow of mouse. The MSC were infected by lentivirus with infection efficiency 78%, the infected MSC were injected into BALB/c mice via tail veins in concentration of 1×10(6) /mouse. The mice were randomly divided into 4 group according to 4 time points as 1, 2, 5 and 7 days. The lung tissue and bone marrow were taken and made of frozen sections and smears respectively in order to observed the distributions of MSC. The results indicated that the lentiviral infected MSC displayed phenotypes and biological characteristics which conformed to MSC by immunophenotyping analysis and induction differentiation detection. After the MSC were infected with optimal viral titer MOI = 50, the cell growth no significantly changed; the fluorescent microscopy revealed that the distributions of MSC in bone marrow on day 1, 2, 5 and 7 were 0.50 ± 0.20, 0.67 ± 0.23, 0.53 ± 0.14, 0.33 ± 0.16; those in lung tissue were 0.55 ± 0.15, 0.47 ± 0.13, 0.29 ± 0.13, 0.26 ± 0.08. It is concluded that the distribution of MSC in lung tissue reaches a peak on day 1, while distribution of MSC in bone marrow reaches a peak on day 2. The distribution of mouse MSC relates with RFP gene expression and implantation of MSC in lung tissue and bone marrow.

[Research progress on immunologic mechanisms of mesenchymal stem cells for treatment of graft-versus-host disease].

Mesenchymal stem cells (MSC) are the non-hematopoietic stem cells with a multi-differentiation potentials, which has a low immunogenicity and immune regulation ability. MSC immune regulation ability is particularly important, such as MSC can inhibit the activation and proliferation of T, B lymphocytes, NK cells and dendritic cells (DC). Meanwhile, MSC is able to reconstruct the human hematopoietic microenvironment, improving the successful rate of hematopoietic stem cell transplantation. Graft versus host disease (GVHD) is the main factor causing hematopoietic stem cell transplantation-related mortality. Based on the above mentioned properties, MSCs are used to treat autoimmune diseases and GVHD, recently. Therefore, deep exploration of the cellular immune mechanisms of MSC to treat GVHD is particularly important. This review focuses on progress of research related to treatment of GVHD by MSC immune mechanisms and briefly summarizes the status of the clinical studies.