ABSTRACT
SARS-CoV2 is highly contagious and the global spread has caused significant medical, social and economic impacts. Other than vaccination, effective public health measures, including contact tracing, isolation and quarantine, is critical for deterring viral transmission, preventing infection progression and resuming normal activities. Viral transmission is affected by many factors but the viral load and vitality could be among the most important ones. Although in vitro culture studies have indicated that the amount of virus isolated from infected people determines the successful rate of virus isolation, whether the viral load carried at the individual level would affect the transmissibility was not known. We aimed to determine whether the Ct value, a measurement of viral load by RT-PCR assay, could differentiate the spreader from the non-spreader in a population of college students. Our results indicate that while at the population level the Ct value is lower, suggesting a higher viral load, in the symptomatic spreaders than the asymptomatic non-spreaders, there is a significant overlap in the Ct values between the two groups. Thus Ct values, or the viral load, at the individual level could not predict the transmissibility. Our studies also suggest that a sensitive method to detect the presence of virus is needed to identify asymptomatic persons who may carry a low viral load but can still be infectious.
ABSTRACT
<p><b>OBJECTIVE</b>To explore the method for labeling Flk1+ CD31- CD34- human bone marrow mesenchymal stem cells (hBMSCs) with ferumoxide-PLL and evaluate the feasibility of its tracing after transplantation into the brains of Macaca Fascicularis.</p><p><b>METHODS</b>The hBMSCs were incubated with ferumoxide-PLL. Trypan blue staining, Prussian blue staining, and transmission electron microscope were performed to show intracellular iron, marking efficiency, and the vigor of the labeled cells. After the hBMSCs were transplanted into the brains of cynomolgus monkeys by stereotaxis, magnetic resonance imaging (MRI) was performed to trace the cells in vivo. Cell survival and differentiation were studied with immunohistochemistry, Prussian blue staining, and HE staining.</p><p><b>RESULTS</b>The marking efficiency of the ferumoxide-PLL was 96%. Iron particles were found intracytoplasmic of the hBMSCs by Prussian blue staining and transmission electron microscopy. The relaxation rates of labeled cells in MRI were 4.4 and 4.2 times higher than those of the unlabeled cells. Hypointensity area was found by MRI three weeks after transplantation. Many hBMSCs and new vessels were found in the transplantation zone by pathological and immunofluorescence methods.</p><p><b>CONCLUSIONS</b>Ferumoxide-PLL can effectively label hBMSCs and thus increase its contrast in MRI results. The cells can survive in the brains of cynomolgus monkeys. The labeled hBMSCs can be traced in vivo by MRI.</p>
Subject(s)
Animals , Humans , Antigens, CD34 , Metabolism , Bone Marrow Cells , Chemistry , Metabolism , Bone Marrow Transplantation , Brain , Metabolism , Brain Chemistry , Contrast Media , Chemistry , Dextrans , Ferrosoferric Oxide , Chemistry , Macaca fascicularis , Magnetic Resonance Imaging , Methods , Magnetite Nanoparticles , Mesenchymal Stem Cell Transplantation , Mesenchymal Stem Cells , Chemistry , Metabolism , Platelet Endothelial Cell Adhesion Molecule-1 , Metabolism , Staining and Labeling , Methods , Vascular Endothelial Growth Factor Receptor-2 , MetabolismABSTRACT
Objective To investigate the imaging manifestations of lung neoplasms in pre- and post- treatment with CT-guided Argon-Helium cryoablation.Methods All the lung neoplasms in 96 patients have been treated with CT-guided percutaneous Argon-Helium targeted cryoablation.All patients have pre- and post-treatment CT scanning in measurement of lesion size and CT value.The CT scanning has been rerpeated afterl,3,6,12 months of treatment.Results Among total 96 cases,there are 82 cases of lung cancer and 14 cases of metastasis with 110 lesions(89 cases with single lesion,7 cases with multiple lesions).The Ar-He cryoablation has been given 103 times in total.The size of each lesion ranged from 1.2 cm to 15.0 cm in diameter with mean value of(4.0?2.5)cm,including 12 lesions less than 2 cm,51 lesions between 2— 4 cm,24 lesions between 4—6 cm,23 lesions over 6 cm.There are 25 patients whose lesions covered by iceball with 1 cm of overloaping it's margin.There are 63 lesions with diameter less than 4 cm gained 100% ablation rate,24 lesions with 4—6 cm diameter gained 95.8% ablation rate,and 23 lesions with over 6 cm diameter gained 69.6% ablation rate.The post-treatment CT show a progressively enlarged round,low density refrigerant area which clearly demarked with non- refrigerant area.The center of each refrigerant area has negative CT value,the mean decreased CT value of lesion instantly after the treatment are about 30— 50 HU with P
