Development of a Peptide Sensor Derived from Human ACE2 for Fluorescence Polarization Assays of the SARS-CoV-2 Receptor Binding Domain.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and the continuing emergence of infectious variants have caused a serious pandemic and a global economic slump since 2019. To overcome the situation and prepare for future pandemic-prone diseases, there is a need to establish a convenient diagnostic test that is quickly adaptable to unexpected emergence of virus variants. Here we report a fluorescent peptide sensor 26-Dan and its application to the fluorescence polarization (FP) assay for the highly sensitive and convenient detection of SARS-CoV-2. The 26-Dan sensor was developed by fluorescent labeling of the 26th amino acid of a peptide derived from the N-terminal α-helix of human angiotensin-converting enzyme 2 (hACE2) receptor. The 26-Dan sensor maintained the α-helical structure and showed FP changes in a concentration-dependent manner of the receptor binding domain (RBD) of the virus. The half maximal effective concentrations (EC50's) for RBD of Wuhan-Hu-1 strain, Delta (B.1.617.2), and Omicron (BA.5) variants were 51, 5.2, and 2.2 nM, respectively, demonstrating that the 26-Dan-based FP assay can be adaptable to virus variants that evade standard diagnostic tests. The 26-Dan-based FP assay could also be applied to model screening of a small molecule that inhibits RBD binding to hACE2 and identified glycyrrhizin as a potential inhibitor. The combination of the sensor with a portable microfluidic fluorescence polarization analyzer allowed for the detection of RBD in a femtomolar range within 3 min, demonstrating the assay could be a promising step toward a rapid and convenient test for SARS-CoV-2 and other possible future pandemic-prone diseases.

Relationship between the fasting status during hospitalisation, the length of hospital stay and the outcome.

The effects of long-term fasting on the prognosis and hospital economy of hospitalised patient have not been established. To clarify the effects of long-term fasting on the prognosis and hospital economy of hospitalised patients, we conducted a prospective observational study on the length of hospital stay of patients hospitalised at thrity-one private university hospitals in Japan. We conducted a prospective observational study on the effects of fasting period length on the length of hospital stay and outcome of patients hospitalised for 3 months in those hospitals. Of the 14 172 cases of hospitalised patients during the target period on the reference day, 770 cases (median 71 years old) were eligible to fast for the study. The length of hospital stay for fasting patients was 33 (4-387) days, which was about 2·4 times longer than the average length of hospital stay for all patients. A comparative study showed the length of hospital stay was significantly longer in the long-term-fasting (fasting period > 10 d; n 386) group than in the medium-term-fasting (< 10 d; n 384) group (median 21 v. 50; P < 0·0001). Although the discharge to home rate was significantly higher in the medium-term-fasting group (71·4 % v. 36·5 %; P < 0·0001), the mortality rate was significantly higher in the long-term fasting group (10·8 % v. 25·8 %; P < 0·0001). It was verified that the longer the fasting period during hospitalisation, the longer the length of hospital stay and lower home discharge rate, thus indicating that patient quality of life and hospital economy may be seriously dameged.