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Background: Tillage measures have been effectively adopted for mitigating waterlogging damage in field crops, yet little is known about the role of tillage measures in crop responses to waterlogging. A field experiment was performed to investigate the effect of conventional planting (CK), small ridge planting (SR), big ridge planting (BR) and film side planting (FS) on soil available nutrients and enzymatic activity, chlorophyll contents, leaf nutrients, soluble protein, soluble sugar, nitrate reductase, antioxidant enzyme activity, lipid peroxidation, agronomic traits and yield of rapeseed under waterlogging stress conditions. Results: Tillage measures remarkably improved rapeseed growth and yield parameters under waterlogging stress conditions. Under waterlogging conditions, rapeseed yield was significantly increased by 33.09 and 22.70% in the SR and BR groups, respectively, compared with CK. Correlation analysis showed that NO3−-N, NH4+-N, and urease in soils and malonaldehyde (MDA), superoxide dismutase (SOD), and nitrate reductase in roots were the key factors affecting rapeseed yield. The SR and BR groups had significantly increased NO3−-N by 180.30 and 139.77%, NH4+-N by 115.78 and 66.59%, urease by 41.27 and 26.45%, SOD by 6.64 and 4.66%, nitrate reductase by 71.67 and 26.67%, and significantly decreased MDA content by 14.81 and 13.35% under waterlogging stress, respectively, compared with CK. In addition, chlorophyll and N content in leaves, soluble sugar and POD in roots, and most agronomic traits were also significantly enhanced in response to SR and BR under waterlogging conditions. Conclusion: Overall, SR and BR mitigated the waterlogging damage in rapeseed mainly by reducing the loss of soil available nitrogen, decreasing the MDA content in roots, and promoting urease in soils and SOD and nitrate reductase in roots. Finally, thorough assessment of rapeseed parameters indicated that SR treatment was most effective followed by BR treatment, to alleviate the adverse effects of waterlogging stress. [ABSTRACT FROM AUTHOR]

Background: Macrolactins, a type of macrolide antibiotic, are toxic to the producer strains. As such, its level is usually maintained below the lethal concentration during the fermentation process. To improve the production of macrolactins, we applied adaptive laboratory evolution technology to engineer a saline-resistant mutant strain. The hypothesis that strains with saline resistance show improved macrolactins production was investigated. Results: Using saline stress as a selective pressure, we engineered a mutant strain with saline resistance coupled with enhanced macrolactins production within 60 days using a self-made device. As compared with the parental strain, the evolved strain produced macrolactins with 11.93% improvement in non-saline stress fermentation medium containing 50 g/L glucose, when the glucose concentration increased to 70 g/L, the evolved strain produced macrolactins with 71.04% improvement. RNA sequencing and metabolomics results revealed that amino acid metabolism was involved in the production of macrolactins in the evolved strain. Furthermore, genome sequencing of the evolved strain revealed a candidate mutation, hisDD41Y, that was causal for the improved MLNs production, it was 3.42 times higher than the control in the overexpression hisDD41Y strain. Results revealed that saline resistance protected the producer strain from feedback inhibition of end-product (macrolide antibiotic), resulting in enhanced MLNs production. Conclusions: In the present work, we successfully engineered a mutant strain with enhanced macrolactins production by adaptive laboratory evolution using saline stress as a selective pressure. Based on physiological, transcriptomic and genetic analysis, amino acid metabolism was found to benefit macrolactins production improvement. Our strategy might be applicable to improve the production of other kinds of macrolide antibiotics and other toxic compounds. The identification of the hisD mutation will allow for the deduction of metabolic engineering strategies in future research. [ABSTRACT FROM AUTHOR]

Background: Previous studies showed that recovered coronavirus disease 2019 (COVID-19) patients can have a subsequent positive polymerase chain reaction (PCR) test for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after they are discharged from the hospital. Understanding the epidemiological characteristics of recovered COVID-19 patients who have a re-positive test is vital for preventing a second wave of COVID-19.Methods: This retrospective study analyzed the epidemiological and clinical features of 20,280 COVID-19 patients from multiple centers in Wuhan who had a positive PCR test between December 31, 2019, and August 4, 2020. The RT-PCR test results for 4079 individuals who had close contact with the re-positive cases were also obtained.Results: In total, 2466 (12.16%) of the 20,280 patients had a re-positive SARS-CoV-2 PCR test after they were discharged from the hospital, and 4079 individuals had close contact with members of this patient group. All of these 4079 individuals had a negative SARS-CoV-2 PCR test.Conclusions: This retrospective study in Wuhan analyzed the basic characteristics of recovered COVID-19 patients with re-positive PCR test and found that these cases may not be infectious. [ABSTRACT FROM AUTHOR]

Objective: Deep venous thrombosis (DVT) is a severe complication in longitudinally extensive transverse myelitis (LETM) patients. It may interfere with LETM treatment and delay the recovery of the spinal dysfunction. However, there is less data about the prevalence and risk factors of DVT in patients with LETM. We analyzed data retrospectively to ascertain the prevalence of DVT and the clinical risk factors for DVT.Methods: Clinical data on 255 LETM patients were collected from medical records. All patients were performed color Doppler ultrasound(US) to screen DVT in both lower extremities when admitted. Clinical characteristics of LETM patients with DVT were compared with those without DVT using corresponding statistical methods. Multivariate logistic regression was performed to identify risk factors related to DVT.Results: DVT were found in 11.8% patients with LETM. Univariate analysis showed that age, muscle force and elevated baseline D-dimer were risk factors for DVT. After multivariate logistic regression, age, dyslipidemia, segments of lesions, and elevated baseline D-dimer remained significant independent risk factors.Conclusions: DVT is common in patients with LETM and related to patient's age, dyslipidemia, segments of lesions, and elevated baseline D-dimer. Early recognition of DVT and thrombosis prophylaxis are appropriate in patients with LETM. [ABSTRACT FROM AUTHOR]

Background: Neuromyelitis optica spectrum disorders (NMOSD) are demyelinating autoimmune diseases in the central nervous system (CNS) that are characterized by a high relapse rate and the presence of anti-aquaporin 4 antibodies (AQP4-IgG) in the serum. Azathioprine (AZA) is a first-line immunomodulatory drug that is widely used for the treatment of patients with NMOSD. However, the efficacy and safety of AZA vary in different individuals.Method: Thirty-two patients with NMOSD who regularly took AZA were enrolled in the study at Beijing Tiantan Hospital, Capital Medical University. The efficacy of AZA was evaluated using the expanded disability status scale (EDSS) and the annual relapse rate (ARR). The erythrocyte concentrations of AZA metabolites were detected using an LC-MS/MS method.Results: The erythrocyte concentrations of 6-thioguanine nucleotides (6-TGNs) and 6-methylmercaptopurine nucleotides (6-MMPNs) were 202.03 ± 63.35 pmol/8*108 RBC and 1618.90 ± 1607.06 pmol/8*108 RBC, respectively. After the patients had received AZA therapy for more than one year, the EDSS score decreased from 5.21 ± 0.24 to 2.57 ± 0.33 (p < 0.0001), and the ARR decreased from 1.41 ± 0.23 to 0.36 ± 0.09 (p < 0.0001). The 6-TGN and 6-MMPN levels were significantly different between the non-relapsed and relapsed groups (p < 0.0001, p = 0.006, respectively). A higher ARR was significantly correlated with higher erythrocyte concentrations of 6-TGNs (p < 0.0001) and 6-MMPNs (p = 0.004).Conclusion: AZA can reduce the EDSS score and ARR in NMOSD patients. Additionally, the efficacy of AZA is significantly related to the erythrocyte concentrations of 6-TGNs and 6-MMPNs. Within the safe upper limits, a higher concentration of 6-TGNs is associated with better efficacy of AZA.Trial Registration Number: ISRCTN16551495 , retrospectively registered on May 22, 2017. [ABSTRACT FROM AUTHOR]

Background: Congenital goiter is a common thyroid metabolic disorder characterized by low levels of thyroid hormone, subsequent secretion of excess thyroid-stimulating hormone (TSH) from the pituitary gland, and compensatory hyperplasia of the glands. The presence of signet ring cells (SRCs) does not provide sufficient evidence for the diagnosis of a thyroid tumor, making histopathological diagnosis challenging. In addition, SRCs can also appear in congenital goiter. Therefore, a comprehensive diagnosis of congenital goiter is warranted based on clinical symptoms, autopsy, histopathology, and laboratory examination. Case presentation: A juvenile giraffe at the Ordos Zoo in Ordos presented with symptoms of loss of appetite, serious salivation, and slow growth rate since birth. Its height and weight were significantly lower than those of other giraffes of the same age. The animal ultimately died at 17 months of age. Autopsy revelaed that the thyroids were hard, with an uneven surface and with the presence of many small raised follicles, and dense in cross-section. Other organs were visibly atrophic. Histopathologically, diffuse follicles were irregular in size and shape in the hyperplastic goiter. Some follicles were collapsed due to lack of colloids. The follicles were lined by single or multiple layers of hyperplastic follicular cells (HFCs), some of which were exfoliated in the lumen. The HFCs were either cuboidal with eosinophilic cytoplasm and many red small granules or showed SRC differentiation, with nuclei pressed to one edge of the cell and distorted by cytoplasmic mucin that appeared as a single clear vacuole HFCs and as a foamy, multivesicular cytoplasmic material in others. Scattered necrosis of myocardial cells and hepatocytes, cerebral hemorrhage, necrosis of intestinal villi, and obvious atrophy of organs were also observed. Immunohistochemical tests were strongly positive for thyroglobulin and thyroid transcription factor-1 (TTF-1) in the cytoplasm of HFCs. Conclusions: Here we present a case of congenital goiter with areas of SRC differentiation in the thyroid of a juvenile giraffe. [ABSTRACT FROM AUTHOR]