BACKGROUND:Very smal embryonic-like stem cells are a kind of non-hemopoietic stem cells, which have similar biological characteristics to embryonic stem cells. But the method of its culture and in vitro proliferation is rarely reported. Studies have speculated that human embryonic fibroblasts can provide a good microenvironment for in vitro culture and proliferation of very smal embryonic-like stem cells.
OBJECTIVE:To isolate and cultivate human embryonic fibroblasts derived from human embryonic trunks and to establish a feeder layer culture system of human embryonic fibroblasts for culturing very smal embryonic-like stem cells derived from human bone marrow.
METHODS:The human embryonic fibroblasts were isolated from the subcutaneous connective tissue of human embryos at pregnant 5-9 weeks using trypsin digestion method. Different concentrations of mitomycin C were used to pretreat feeder layers, which were used for cultivating very smal embryonic-like stem cells derived from human bone marrow. The effects of human embryonic fibroblasts and feeder layers were assessed by cel morphology and growth curves.
RESULTS AND CONCLUSION:The human embryonic fibroblasts were successful y isolated and cultivated from human embryos, and they could be passaged beyond the 24th generation. The biologic characteristics of the cells had no changes after passage and cryopreservation. The optimal concentration of mytomcin C to inhibit proliferation of human embryonic fibroblasts was l2 mg/L for 3 hours. The human embryonic fibroblasts derived from human embryos are successful y isolated and cultivated and to produce feeder layers for very smal embryonic-like stem cells derived from human bone marrow.

In this paper, the MRI manifestations of 15 patients with benzene toxic encephalopathy were analyzed, and the lesion location, shape, scope and signal were observed. The clinical manifestations of 15 patients were mainly central nervous system damage, and the MRI manifestations were characteristic, with a wide range of lesions, and the shapes were "sunflower-like", "flame-like", "bracket-like" and "butterfly-like", and the MRI signal was sheet-like long T(1), long T(2), fluid attenuated inversion recovery (FLAIR) sequence and diffusion weighted imaging (DWI) high signal, apparent diffusion coeffecient (ADC) map low, equal or high signals. When the patient's diagnosis is unclear, MRI examination may provide clinical basis for diagnosis.
Benzene ; Diffusion Magnetic Resonance Imaging/methods* ; Humans ; Magnetic Resonance Imaging ; Neurotoxicity Syndromes/etiology*

With the number of cases of coronavirus disease-2019 (COVID-19) increasing rapidly, the World Health Organization (WHO) has recommended that patients with mild or moderate symptoms could be released from quarantine without nucleic acid retesting, and self-isolate in the community. This may pose a potential virus transmission risk. We aimed to develop a nomogram to predict the duration of viral shedding for individual COVID-19 patients. This retrospective multicentric study enrolled 135 patients as a training cohort and 102 patients as a validation cohort. Significant factors associated with the duration of viral shedding were identified by multivariate Cox modeling in the training cohort and combined to develop a nomogram to predict the probability of viral shedding at 9, 13, 17, and 21 d after admission. The nomogram was validated in the validation cohort and evaluated by concordance index (C-index), area under the curve (AUC), and calibration curve. A higher absolute lymphocyte count (
Aged ; Aged, 80 and over ; Antibodies, Viral/blood* ; Area Under Curve ; COVID-19/virology* ; Female ; Humans ; Lymphocyte Count ; Male ; Middle Aged ; Nomograms ; Proportional Hazards Models ; Retrospective Studies ; Viral Load ; Virus Shedding