Viral load may impact the diagnostic performance of nasal swabs in nucleic acid amplification test and quantitative antigen test for SARS-CoV-2 detection.

INTRODUCTION: Compared to nasopharyngeal swabs (NPS), there has been insufficient evaluation of the diagnostic performance of nasal swabs (NS) for the detection of severe acute respiratory coronavirus 2 (SARS-CoV-2) in the nucleic acid amplification test (NAAT) and quantitative SARS-CoV-2 antigen test (QAT). METHODS: We prospectively compared healthcare worker-collected and flocked NS within nine days after symptom onset to paired NPS to detect SARS-CoV-2 in NAAT and QAT on the fully automated Lumipulse system. The agreement between sample types was evaluated, and cycle threshold (Ct) values and antigen levels were used as surrogate viral load measures. RESULTS: Sixty sets of NPS and NS samples were collected from 40 patients with COVID-19. The overall agreements between NAAT and QAT samples were 76.7% and 65.0%, respectively. In NAAT, the Ct value of NS was significantly higher, 5.9, than that of NPS. Thirty-nine (95.1%) NS tested positive in 41 positive-paired NPS with Ct ≤ 30. The negative correlation was observed between antigen levels of NS in QAT and Ct values of NS in NAAT (r = -0.88). In QAT, the antigen level of NS was significantly lower than that of NPS. Thirty-six (90.0%) NS tested positive in 40 positive-paired NPS with antigen levels >100 pg/mL, which were collected significantly earlier than those with antigen levels ≤100 pg/mL. CONCLUSIONS: In NAAT and QAT, NS had limited performance in detecting SARS-CoV-2 compared to NPS. However, NS may be helpful for patients with COVID-19 with high viral loads or those in the early stages of the illness.

Does the timing of saliva collection affect the diagnosis of SARS-CoV-2 infection?

We evaluated the optimal timing of saliva sample collection to diagnose the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. We obtained 150 saliva samples at four specific time points from 13 patients with confirmed SARS-CoV-2 infection. The time points were (1) early morning (immediately after waking), (2) immediately after breakfast before tooth brushing, (3) 2 h after breakfast, and (4) before lunch. On the 2nd hospital day, patients collected saliva at the four time points by themselves. We collected samples at two time points, (1) and (3), from the 3rd hospital day to day 9 following symptom onset. In 52 samples collected at the four time points, there was no significant difference. Meanwhile, there was no significant difference in the positive proportion or the viral load between the two time points in both analyses by the day from symptom onset and by all samples. In this study, there was no difference in the positive proportions in saliva collected at various time points within 9 days after symptom onset. The timing of saliva collection was not affected by the diagnosis of SARS-CoV-2 infection.

Evaluation of false positives in the SARS-CoV-2 quantitative antigen test.

INTRODUCTION: Highly sensitive reagents for detecting SARS-CoV-2 antigens have been developed for accurate and rapid diagnosis till date. In this study, we aim to clarify the frequency of false-positive reactions and reveal their details in SARS-CoV-2 quantitative antigen test using an automated laboratory device. METHODS: Nasopharyngeal swab samples (n = 4992) and saliva samples (n = 5430) were collected. We measured their SARS-CoV-2 antigen using Lumipulse® Presto SARS-CoV-2 Ag and performed a nucleic acid amplification test (NAAT) using the Ampdirect™ 2019 Novel Coronavirus Detection Kit as needed. The results obtained from each detection test were compared accordingly. RESULTS: There were 304 nasopharyngeal samples and 114 saliva samples were positive in the Lumipulse® Presto SARS-CoV-2 Ag test. All positive nasopharyngeal samples in the antigen test were also positive for NAAT. In contrast, only three (2.6%) of all the positive saliva samples in the antigen test were negative for NAAT. One showed no linearity with a dilute solution in the dilution test. Additionally, the quantitative antigen levels of all the three samples did not decrease after reaction with the anti-SARS-CoV-2 antibody. CONCLUSIONS: The judgment difference between the quantitative antigen test and NAAT seemed to be caused by non-specific reactions in the antigen test. Although the high positive and negative predictive value of this quantitative antigen test could be confirmed, we should consider the possibility of false-positives caused by non-specific reactions and understand the characteristics of antigen testing. We recommend that repeating centrifugation before measurement, especially in saliva samples, should be performed appropriately.

Analysis of major BCR-ABL1 mRNA by digital polymerase chain reaction is useful for prediction of international scale.

BACKGROUND: Major BCR-ABL1 mRNA in patients with chronic myeloid leukemia (CML) has generally been analysed by real-time polymerase chain reaction (PCR). Application of the international scale (IS) for the quantification of major BCR-ABL1 mRNA has been recommended in several sets of guidelines, including those of the European LeukemiaNet. The aim of this study was to clarify the efficacy of digital PCR technology for the IS of BCR-ABL1 mRNA in the patients with CML by comparing with real-time PCR. METHODS: The analysis of BCR-ABL1 mRNA was carried out by the Ipsogen® BCR-ABL1 Mbcr IS-MMR DX Kit (Qiagen), and the QuantStudio 3D Digital PCR System (Thermo Fisher Scientific ) using 20 peripheral blood samples obtained from the 9 patients with CML at Sapporo Medical University Hospital. RESULTS: The correlation between the data obtained by digital PCR and by real-time PCR was really high at R = 0.96. The detection limit of digital PCR was up to 0.003% and was equal to IS with 0.01% or less in comparison with real-time PCR. CONCLUSIONS: Digital PCR technology is promising for predicting the IS value with similar efficacy to real-time PCR and should be useful for simple monitoring of the effects of tyrosine kinase inhibitor (TKI) treatments.

Down-regulation of hTERT expression plays an important role in 15-deoxy-Delta12,14-prostaglandin J2-induced apoptosis in cancer cells.

The cyclopentenone prostaglandin 15-deoxy-Delta12,14-prostaglandin J2 (15d-PGJ2) has been shown to possess antineoplastic activity in human cancers of various origins. However, the mechanism of the antineoplastic activity of 15d-PGJ2 remains to be completely elucidated. It has been reported that inhibiting the expression of human telomerase reverse transcriptase (hTERT), a major determinant of telomerase activity, induces rapid apoptosis in cancer cells. In this study, we investigated the effect of 15d-PGJ2 on hTERT expression. Treatment with 30 microM 15d-PGJ2 for 72 h induced apoptosis in the colon cancer cells LS180. 15d-PGJ2 treatment decreased hTERT protein expression in a dose-dependent manner. Down-regulation of hTERT expression by hTERT-specific small inhibitory RNA induced apoptosis. These results indicate that the down-regulation of hTERT expression by 15d-PGJ2 plays an important role in its proapoptotic properties. Since 15d-PGJ2 reduced hTERT mRNA expression, we examined the effect of 15d-PGJ2 on the DNA-binding activity of c-Myc, specificity protein 1 (Sp1) and estrogen receptor (ER) to the hTERT gene promoter using an electrophoretic mobility shift assay. 15d-PGJ2 attenuated the DNA-binding of all three transcriptional factors. Further, we observed that 15d-PGJ2 inhibited the DNA binding of these factors by different mechanisms; suppressed c-Myc mRNA expression, enhanced Sp1 protein degradation via the ubiquitin-proteasome pathway and inhibited ERbeta phosphorylation at serine residues. We conclude that hTERT down-regulation by 15d-PGJ2 plays an important role in its proapoptotic properties. Furthermore, 15d-PGJ2 inhibits the transcriptional activity of c-Myc, Sp1 and ER by three different mechanisms and results in the transcriptional repression of the hTERT gene.

Survivin plays as a resistant factor against tamoxifen-induced apoptosis in human breast cancer cells.

Tamoxifen has been the mainstay of endocrine therapy for estrogen receptor-positive breast cancer. However, approximately 40% of breast cancer patients do not respond to tamoxifen treatment. Further, most tumors eventually acquire tamoxifen resistance. Therefore, it is necessary to develop effective modalities to enhance the efficacy of tamoxifen in breast cancer treatment. In this study, we investigated the mechanism by which breast cancer cells develop resistance against tamoxifen from the viewpoint of tamoxifen-induced apoptosis. Overexpression of the anti-apoptotic molecule survivin rendered the human breast cancer cells MCF-7 resistant to tamoxifen-induced apoptosis. To examine whether the down-regulation of survivin can enhance tamoxifen-induced apoptosis, we introduced siRNA targeting the survivin gene (survivin-siRNA) into MCF-7 cells. Survivin-siRNA transfection not only induced apoptosis without tamoxifen treatment but also augmented the tamoxifen-induced apoptosis. We have previously demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (HRIs), which are widely used to reduce the serum cholesterol levels in hypercholesterolemia patients, decreases survivin expression in colon cancer cells. To develop a pharmacological approach for improving the efficacy of tamoxifen treatment, we determined whether HRIs can enhance tamoxifen-induced apoptosis. Lovastatin, an HRI, down-regulated the expression of survivin protein in MCF-7 cells in a dose-dependent manner. In addition, the proportion of apoptotic cells induced by the tamoxifen and lovastatin combination was greater than the theoretical additive effect. These results suggest that survivin may function as a factor inducing resistance against tamoxifen-induced apoptosis, and the combined use of tamoxifen and HRI may be a novel approach to overcome tamoxifen resistance in breast cancer.

15-deoxy-Delta(12,14)-prostaglandin J2 inhibits G2-M phase progression in human breast cancer cells via the down-regulation of cyclin B1 and survivin expression.

The cyclopentenone prostaglandin 15-deoxy-Delta(12,14)-prostaglandin J(2) (15d-PGJ(2)) exerts a growth inhibitory effect on cancer cells, and this effect is linked to the induction of apoptosis or cell cycle arrest. Induction of apoptosis by 15d-PGJ(2) is associated with the down-regulation of anti-apoptotic proteins. G(0)-G(1)-->S phase progression is inhibited by 15d-PGJ(2) via the degradation of cyclin D1. In this study, we further investigated the mechanism by which 15d-PGJ(2) inhibits cancer cell growth by using the breast cancer cell lines MCF-7 and T-47D. Treatment with 20 microM 15d-PGJ(2) for 72 h completely blocked the growth in both cell lines. However, the proportions of apoptotic MCF-7 and T-47D cells were 21.1% and 40.9%, respectively, indicating that the induction of apoptosis did not appear to fully account for growth inhibition by 15d-PGJ(2). Cell cycle analysis using cells synchronized at the G(0)-G(1) or S phase revealed that 15d-PGJ(2) blocked not only G(0)-G(1)-->S phase progression but also G(2)-M phase progression. The expression of both cyclins D1 and B1 was decreased by 15d-PGJ(2). Furthermore, 15d-PGJ(2) inhibited aurora-B kinase activity, which coincided with the down-regulation of survivin. Thus, 15d-PGJ(2) induced cell cycle arrest at the G(2)-M phase via inhibition of cyclin B1 expression and aurora-B kinase activity. We conclude that survivin may be an important target for 15d-PGJ(2), and its down-regulation may lead to a decrease in aurora-B kinase activity.