A SARS-CoV-2 Delta Variant Containing Mutation in the Probe Binding Region Used for qRT-PCR Test in Japan Exhibited Atypical PCR Amplification and Might Induce False Negative Result

A recent pandemic of SARS-CoV-2 infection has caused severe health problems and substantially restricted social and economic activities. To cope with such an outbreak, the identification of infected individuals with high accuracy is vital. qRT-PCR plays a key role in the diagnosis of SARS-CoV-2 infection. The N protein-coding region is widely analyzed in qRT-PCR for the diagnosis of SARS-CoV-2 infection in Japan. We recently encountered two cases of SARS-CoV-2-positive specimens showing atypical amplification curves in the qRT-PCR. We performed whole-genome sequencing and found that the virus was a Delta-type variant of SARS-CoV-2 with a single nucleotide mutation in the probe-binding site. To evaluate the extent of spread of the variant in the area, we performed whole viral genome sequencing of samples collected from 61 patients infected with SARS-CoV-2 during the same time and in the same area. There were no other cases with the same mutation, indicating that the variant had not spread in the area. Furthermore, we performed phylogenetic analysis with various SARS-CoV-2 sequences deposited in the public database. Hundreds of variants were reported globally, and one in Japan were found to contain the same mutation. Phylogenetic analysis showed that the variant was very close to other Delta variants endemic in Japan but quite far from the variants containing the same mutation reported from outside Japan, suggesting that the variant would have been sporadically generated in some domestic areas. These findings propose two key points: i) mutations in the region used for SARS-CoV-2 qRT-PCR can cause abnormal amplification curves; therefore, the qRT-PCR result should not just be judged in an automated manner, but also manually checked by the examiner to prevent false-negative results, and ii) various mutations can be generated sporadically and unpredictably; therefore, efficient and robust screening systems are needed to promptly monitor the emergence of de novo variants.

Use of IABP in contrast media-induced anaphylactic shock: the ultimate lifesaver.

Anaphylactic reaction to contrast media during selective coronary angiography is a rare occurrence. It can be occasionally resistant to medical treatment leading to cardiovascular collapse and death. The use of intra-aortic balloon pump (IABP) counter-pulsation when the supportive medical treatment fails during anaphylactic shock is not well documented in the literature. We report a case of a severe contrast media-induced anaphylactic shock which failed to respond to the supportive medical management and the timely insertion of IABP for further circulatory support that prevented death in a patient who had an elective diagnostic coronary angiography. The clinical diagnosis of anaphylaxis was challenging at the onset of shock as the typical rash developed after a few minutes.

Anti-cancer activity of nitrones in the Apc(Min/+) model of colorectal cancer.

Abstract The nitrones of alpha-phenyl-tert-butyl nitrone (PBN) and 4-hydroxyl-PBN (4-OH-PBN) that have anti-cancer activity in models of liver cancer and glioblastomas were tested in the ApcMin/+ mouse model. Mice were administered PBN and 4-OH-PBN in drinking water and intestinal tumour size and number assessed after 3-4 months. Throughout the experiment, contrast-enhanced magnetic resonance imaging (MRI) was used to monitor colon tumours. MRI data showed a time-dependent significant increase in total colonic signal intensity in sham-treated mice, but a significant decrease for PBN-treated mice and slight decrease for 4-OHPBN treated mice, probably due to the limited water solubility of 4-OH-PBN. Final pathological and percentage survival data agreed with the MRI data. PBN had little effect on oxaliplatin-mediated killing of HCT116 colon cancer cells and caused only a slight decrease in the amount of active fraction caspase 3 in oxaliplatin-treated cells. PBN has significant anti-cancer activity in this model of intestinal neoplasia.