The relationship between SARS-COV-2 RNA positive duration and the risk of recurrent positive.

BACKGROUND: The management of discharge COVID-19 patients with recurrent positive SARS-CoV-2 RNA is challenging. However, there are fewer scientific dissertations about the risk of recurrent positive. The aim of this study was to explore the relationship between SARS-COV-2 RNA positive duration (SPD) and the risk of recurrent positive. METHODS: This case-control multi-center study enrolled participants from 8 Chinese hospital including 411 participants (recurrent positive 241). Using unadjusted and multivariate-adjusted logistic regression analyses, generalized additive model with a smooth curve fitting, we evaluated the associations between SPD and risk of recurrent positive. Besides, subgroup analyses were performed to explore the potential interactions. RESULTS: Among recurrent positive patients, there were 121 females (50.2%), median age was 50 years old [interquartile range (IQR): 38-63]. In non-adjusted model and adjusted model, SPD was associated with an increased risk of recurrent positive (fully-adjusted model: OR = 1.05, 95% CI: 1.02-1.08, P = 0.001); the curve fitting was not significant (P = 0.286). Comparing with SPD < 14 days, the risk of recurrent positive in SPD > 28 days was risen substantially (OR = 3.09, 95% CI: 1.44-6.63, P = 0.004). Interaction and stratified analyses showed greater effect estimates of SPD and risk of recurrent positive in the hypertension, low monocyte count and percentage patients (P for interaction = 0.008, 0.002, 0.036, respectively). CONCLUSION: SPD was associated with a higher risk of recurrent positive and especially SPD > 28 day had a two-fold increase in the relative risk of re-positive as compared with SPD < 14 day. What's more, the risk may be higher among those with hypertension and lower monocyte count or percentage.

[Comparative study on FTIR spectra of garlic from different geographical populations].

In the present paper, 25 garlic samples from different geographical populations were studied. FTIR spectra for each sample were obtained by using Fourier transform infrared spectrometer, and the similarity of garlic samples from different geographical populations was compared through "quick comparison" function in software of the spectrometer. The results showed that there are differences among FTIR spectra of garlic samples from different geographical populations. The quick comparison showed that the similarity is from 76.3% to 99.8% and the diversity of differentiation is more obvious. To some extent, the results reflected the effects of populations environment on physical and chemical properties of garlic. The study provided a simple, rapid, non-destructive and new methods for identification and evaluation of garlic germplasm resources.