Objective:To investigate the characteristics of digestive system symptoms and its relation with the time of nucleic acid continuous positive in population infected with severe acute respiratory syndrome coronavirus 2 Omicron variant, and to analyze the abdominal computed tomography (CT) features of patients infected with Omicron variant.Methods:From April 11 to May 23, 2022, a questionnaire survey was conducted in patients infected with Omicron variant admitted to the Shanghai National Convention and Exhibition Center Fangcang Hospital. The questionnaire included basic information, the start time of nucleic acid positive, respiratory symptoms, digestive system syptoms and outcomes, etc.Combined with the clinical data, the relation between digestive tract symptoms and the time of nucleic acid continuous positive were analyzed. Thoracic and abdominal CT were performed for patients with continuous positive nucleic acid results ≥10 d, and the relationship between the abdominal CT imaging characteristics and the time of nucleic acid continuous positive was analyzed. Independent sample t-test and multivariate logistic regression were used for statistical analysis. Results:A total of 4 360 valid questionnaires were collected, including 2 475 males and 1 885 females, with a hospital stay of (6.8±4.9) d. Among the 4 360 patients, 1 979 patients (45.4%) had gastrointestinal symptoms such as loss of appetite, abdominal discomfort or pain, constipation and diarrhea. The time of nucleic acid continuous positive in patients with gastrointestinal symptoms was (7.4±5.5) d, which was longer than that of patients without gastrointestinal symptoms (6.5±3.6) d, and the difference was statistically significant ( t=3.78, P<0.001). During the isolation period in the Fangcang Hospital, the time of nucleic acid continuous positive in patients with complete remission of digestive tract symptoms was shorter than that of patients with no remission of digestive tract symptoms ((7.3±5.2) d vs. (8.5±5.7) d), and the difference was statistically significant ( t=2.25, P=0.025). The results of multivariate logistic regression analysis showed that the combination of gastrointestinal symptoms was an independent risk factor for continuous positive nucleic acid result ≥10 d ( OR=1.316, 95% confidence interval 1.294 to 2.205, P=0.046). Among the 299 patients with continuous positive nucleic acid results≥10 d, 187 cases (62.5%) had gastrointestinal symptoms, and 146 cases (48.8%) had abdominal CT findings of thickening of the gastroduodenal wall, thickening of the small intestinal wall, indistinct mesenteric vessels of the small intestine, and dilatation and pneumatosis of the colon. In patients with continuous positive nucleic acid results ≥10 d, abdominal CT indicated that patients with gastrointestinal imaging changes had a longer time of nucleic acid continuous positive than those without gastrointestinal imaging changes ((16.0±2.8) d vs. (13.0±2.1) d), and the difference was statistically significant ( t=2.62, P=0.009). Conclusions:Digestive system symptoms are common in patients infected with Omicron variant. The time of nucleic acid continuous positive in patients with gastrointestinal symptoms is longer than those without gastrointestinal symptoms. Some patients may have gastrointestinal lesions on abdominal CT.

Background: Disrupted circadian rhythms have been associated with the development of irritable bowel syndrome (IBS). In some IBS patients, the symptoms may present with circadian fluctuations. Enterochromaffin cells (EC cells) and tryptophan hydroxylase 1 (TPH1) - 5 - hydroxytryptamine (5 - HT) signaling pathway are currently recognized as the key pathophysiological mechanism of IBS. Aims: To explore whether Bmal1, the core circadian clock gene, is involved in the occurrence of IBS by regulating TPH1-5-HT signaling pathway in EC cells. Methods: Normal Sprague-Dawley (SD) rats and IBS-model SD rats, as well as wild type (WT) and intestine-specific Bmal1 knockout (Bmal1