Recurrence of SARS-CoV-2 PCR positivity in COVID-19 patients: a single center experience and potential implications

IMPORTANCEHow to appropriately care for patients who become PCR-negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is still not known. Patients who have recovered from coronavirus disease 2019 (COVID-19) could profoundly impact the health care system if a subset were to be PCR-positive again with reactivated SARS-CoV-2. OBJECTIVETo characterize a single center COVID-19 cohort with and without recurrence of PCR positivity, and develop an algorithm to identify patients at high risk of retest positivity after discharge to inform health care policy and case management decision-making. DESIGN, SETTING, AND PARTICIPANTSA cohort of 414 patients with confirmed SARS-CoV-2 infection, at The Second Affiliated Hospital of Southern University of Science and Technology in Shenzhen, China from January 11 to April 23, 2020. EXPOSURESPolymerase chain reaction (PCR) and IgM-IgG antibody confirmed SARS-CoV-2 infection. MAIN OUTCOMES AND MEASURESUnivariable and multivariable statistical analysis of the clinical, laboratory, radiologic image, medical treatment, and clinical course of admission/quarantine/readmission data to develop an algorithm to predict patients at risk of recurrence of PCR positivity. RESULTS16.7% (95CI: 13.0%-20.3%) patients retest PCR positive 1 to 3 times after discharge, despite being in strict quarantine. The driving factors in the recurrence prediction model included: age, BMI; lowest levels of the blood laboratory tests during hospitalization for cholinesterase, fibrinogen, albumin, prealbumin, calcium, eGFR, creatinine; highest levels of the blood laboratory tests during hospitalization for total bilirubin, lactate dehydrogenase, alkaline phosphatase; the first test results during hospitalization for partial pressure of oxygen, white blood cell and lymphocyte counts, blood procalcitonin; and the first test episodic Ct value and the lowest Ct value of the nasopharyngeal swab RT PCR results. Area under the ROC curve is 0.786. CONCLUSIONS AND RELEVANCEThis case series provides clinical characteristics of COVID-19 patients with recurrent PCR positivity, despite strict quarantine, at a 16.7% rate. Use of a recurrence prediction algorithm may identify patients at high risk of PCR retest positivity of SARS-CoV-2 and help modify COVID-19 case management and health policy approaches. Key PointsO_ST_ABSQuestionC_ST_ABSWhat are the characteristics, clinical presentations, and outcomes of COVID-19 patients with PCR retest positivity after resolution of the initial infection and consecutive negative tests? Can we identify recovered patients, prior to discharge, at risk of the recurrence of SARS-CoV-2 PCR positivity? FindingsIn this series of 414 COVID-19 inpatients discharged to a designated quarantine center, 69 retest positive (13 with 2 readmissions, and 3 with 3 readmissions). A multivariable model was developed to predict the risk of the recurrence of SARS-CoV-2 PCR positivity. MeaningRate and timing of the recurrence of PCR positivity following strict quarantine were characterized. Our prediction algorithm may have implications for COVID-19 clinical treatment, patient management, and health policy.

Analysis on interference effects of vitamin C on three kinds of glucose detection methods / 国际检验医学杂志

Objective To investigate the interference effects of vitamin C on three different detection methods of blood glucose.Methods According to CLSI EP7-A2 document,5% volume of vitamin C(series concentrations) solution was added to fresh mixed serum,then hexokinase method(A),glucose oxidase method(B) and glucose reductase electrode method(C) were used to detect the level of fresh mixed serum glucose.The interference level of vitamin C on three different detection methods of blood glucose was evaluated.Results In 1 250 mg/L vitamin C,there was no interference on the method A for detecting blood glucose.In 156 mg/L vitamin C,it caused unacceptable negative interference on the method B and unacceptable positive interference on the method C.Moreover the interference degree of these two methods was increased with vitamin C concentration increase,but the same concentration of vitamin C had no significant difference on detecting different blood glucose levels by the same detection method.Conclusion High concentration of vitamin C can cause significant interference on glucose detection by glucose oxidase method and glucose reductase electrode method.

Effects of luteolin on the secretion of inflammatory cytokines from activated RAW264.7 macrophages / 医学研究生学报

Objective Inflammation is a defensive reaction of body , but excessive inflammatory response can lead to physi-cal injury.The aim of this study was to explore the effects of luteolin on the secretion of inflammatory cytokines from lipopolysaccharide (LPS) and interferon-g(IFN-γ) activated RAW264.7 cells. Methods RAW264.7 cells were divided into 5 groups: control group (without any medicine), M1 group (polarized M1 cells activated by final concentration of 10 ng/mL LPS+20 ng/mL IFN-γ), M1+5L group (simultaneous activation of LPS and IFN-γplus final concentration of 5μmol/L luteolin), M1+10L group(simultaneous activa-tion of LPS and IFN-γplus 10μmol/L luteolin), M1+20L group(simultaneous activation of LPS and IFN-γplus 20μmol/L luteolin). The cell morphological transformation was observed by laser confocal microscope ;the mRNA levels of iNOS , IL-1βand IL-6 were test-ed by real-time quantitative PCR respectively;the secretion levels of TNF-αand IL-6 in culture supernatant were detected by ELISA;the changes of p-STAT3 (ser727) protein pathways were examined by western blot. Results Cellular morphology of activated RAW 264.7 cells changed obviously .Compared with the control group , the mRNA levels of iNOS, IL-1βand IL-6 decreased significantly in the other 4 groups(P<0.05).The iNOS level in M1+20L group significantly de-creased compared with M1 group[(29.52±3.07) vs (98.91±10.65), P<0.01].As to IL-1βlevel, it decreased significantly in M1+10L group(78.38±8.65) and M1+20L group(41.59±6.80) compared with M1 group(110.69±4.12)(P<0.05).While the IL-6 levels decreased significantly in M1+5L group(177.51±19.28), M1+10L group (106.14±5.63), M1+20L group(27.15±1.26), compared with M1 group(394.10±33.47)(P<0.05).LPS+IFN-γcould induce in-creased p-STAT3 (ser727) expression in M1 phenotype of RAW264.7 cells which was proved by its significant increase in M 1 group, M1+5L group and M1+10L group compared with control group (P<0.05).In comparison to M1 group, p-STAT3-ser expression in M1 phenotype downregulated in M1+5L group, M1+10L group, M1+20L group(P<0.05), along with dose-dependent characteristic.Com-pared with control group, the levels of IL-6 and TNF-αincreased significantly in M1 group, M1+5L group and M1+10L group.Com-pared with M1 group, the levels of IL-6 and TNF-αdecreased significantly in M1+5L group, M1+10L group and M1+20L group(P<0.05) , in which IL-6 showed concentration independence and TNF-αshowed no concentration independence . Conclusion Luteolin inhibits the secretion of pro-inflammatory cytokines through the down-regulation of p-STAT3 so as to exert anti-inflammatory effects .

Relationship Between Serum Levels of High Sensitivity Cardiac Troponin T and the Severity of Coronary Lesions in Patients With Stable Coronary Artery Disease / 中国循环杂志

Objective: To investigate the relationship between serum levels of high sensitivity cardiac troponin T (hs-cTnT) and the severity of coronary lesions in patients with stable coronary artery disease (SCAD). Methods: A total of 450 SCAD patients with coronary angiography (CAG) conifrmed diagnosis in our hospital were studied, and serum levels of hs-cTnT were examined at 3 days prior CAG in all patients. Based on tertiles of Gensini score, the patients were divided into 3 groups: Low score group,n=153 patients with Gensini score28. The relationships between Gensini score and hs-cTnT levels were analyzed among 3 groups. The optimal cut-off value of hs-cTnT for predicting high Gensini score and the need of revascularization were studied by ROC curve, the relationships between hs-cTnT and high Gensini score, the need of revascularization were further detected by Logistic regression analysis. Results: The median values (25%-75%) of hs-cTnT in Low score group, Intermediate score group and High score group were 6.72 (4.20, 8.93) pg/ml, 7.90 (5.74, 12.68) pg/ml and 14.99 (10.26, 24.30) pg/ml respectively, allP<0.01. ROC curve analysis indicated that the area under curve (AUC) of hs-cTnT for predicting high Gensini score was 0.837 (95% CI 0.803-0.874), for the need of revascularization was 0.772 (95% CI 0.728-0.817); the best cut-off value of hs-TnT for predicting high Gensini score was 10.04 pg/ml and for the need of revascularization was 8.56 pg/ml. Logistic regression analysis suggested that with adjusted age, gender, the history of hypertension, diabetes, smoking, blood levels of creatinine, LDL-C and hs-CRP, hs-cTnT was still an independent predictor for high Gensini score (OR=1.13, 95% CI 1.06-1.20,P<0.001) and for the need of revascularization (OR=1.19, 95% CI 1.14-1.24,P<0.001). Conclusion: Serum level of hs-cTnT has been related to severity of coronary lesions in SCAD patients, hs-cTnT might be used as one of the pre-operative predictor for severe coronary disease and for the need of revascularization.

Development of Muscle Strength Evaluating System Based on Mobile Platform / 生物医学工程学杂志

The development of muscle strength evaluating system based on Android system was developed in this research. The system consists of a lower unit and an intelligent mobile terminal. The pressure sensor of the lower unit was used to collect muscle strength parameters. And the parameters were sent to the Android device through the wireless Bluetooth serial port. Then the Android device would send the parameters to the doctor monitored platform through the Internet. The system realized analyzing the muscle strength parameters and real-time displaying them. After it ran on the Android mobile phones, it showed an effective result which proved that the system combined with mobile platform could make more convenient for the patients to assess their own muscle strength. It also provided reliable data references for doctors to know the patients' rehabilitation condition and to make the next rehabilitation plan.

Analysis on influence of blood transfusion or pregnancy on blood cross-matching / 国际检验医学杂志

Objective To evaluate the influence of blood transfusion or pregnancy on blood cross-matching results.Methods 1 000 specimens with blood transfusion or pregnancy history were collected and performed the blood group typing,blood cross matching,irregular antibody screening and identification by the micro-gel method with the specimens of first time transfuse blood and without pregnancy history as the control.The inconsistency rate of positive negative blood grouping,unqualified rate of blood cross matching and the positive rate of irregular antibody were compared between the two groups by the t-test.The causes influen-cing the blood cross-matching results were analyzed.Results The inconsistency rate of blood cross-matching in the blood transfu-sion or pregnancy group was significantly higher than that in the control group(P 0.05);the positive rate of irregular antibody screening in the blood transfu-sion or pregnancy group was also significantly higher than that in the control group(P <0.05),indicating that the main causes in-fluencing blood cross matching was the existence of irregular antibodies in the patients in vivo.Conclusion Blood transfusion or pregnancy may stimulate the body to produce the irregular antibodies.Therefore the irregular antibody screening should be per-formed before blood transfusion and blood without corresponding antigen will be selected for transfusion according to the antibody identification results for ensuring safe and effective blood transfusion.

The analysis ofβ-lactam antibiotics interference in fructosamine testing / 国际检验医学杂志

Objective To evaluate the interference of 13 kinds of β‐lactam antibiotics in fructosamine detection .Methods A se‐ries of solution of antimicrobial drugs were formulated with water for injection ,and added into the mixture fresh serum volume by 5% .Interfere with antimicrobial drugs on the test results of fructosamine were evaluated .Results When the blood concentrations of cefathiamidine and ticarcillin sodium/clavulanate potassium were up to 37 .5 mg/L and 247 .5 μg/mL respectively ,they began to produce positive interference on fructosamine detection .However ,the degree of interference was not correlated to the serum concen‐tration of fructosamine .Conclusion Cephathiamidine and ticarcillin sodium/clavulanate potassium have positive interference on fructosamine detection .

Preparation and in vivo investigation of artificial cornea made of nano-hydroxyapatite/poly (vinyl alcohol) hydrogel composite.

An artificial cornea consisted of a porous nano-hydroxyapatite/poly (vinyl alcohol) hydrogel (n-HA/PVA-H) skirt and a transparent center poly (vinyl alcohol) hydrogel (PVA-H) were prepared. The n-HA/PVA-H skirt was homogeneously porous and these pores were interconnected. Inter-penetrating network was observed along the interface between the core and the skirt. Artificial corneas were implanted in eyes of rabbit. The corneal tissues were evaluated histological. The results displayed that a good biocompatibility and interlocking had happened between artificial cornea and host tissues. This novel cornea prepared here is potential to be used clinically.

A study of the relation between cAMP in aqueous humor and the intraocular pressure after topical epinephrin / 眼科

The relation between the cAMP content of the aqueous humor and the intraocular pressure after to- pical epinephrin was studied by radioimmunoassay. Two hours after instillation of epinephrin,the aque- ous cAMP rose from 13.54?5.81 pmol/ml to 39.05 ?4.37 pmol/ml,while the IOP and the rate of the aqueous flow decreased by 0.43kpa and 0.76?l/min, and the facility of outflow increased by 0.23?l/min/ kpa.These results revealed that the IOP-lowering effect of epinephrin was mediated by cAMP.