Gut microbiota, circulating cytokines and dementia: a Mendelian randomization study.

BACKGROUND: Some studies have shown that gut microbiota may be associated with dementia. However, the causal effects between gut microbiota and different types of dementia and whether cytokines act as a mediator remain unclear. METHODS: Gut microbiota, cytokines, and five dementia types, including Alzheimer's disease (AD), frontotemporal dementia (FTD), dementia with Lewy body (DLB), vascular dementia (VD), and Parkinson's disease dementia (PDD) were identified from large-scale genome-wide association studies (GWAS) summary data. We used Mendelian randomization (MR) to investigate the causal relationships between gut microbiota, cytokines, and five types of dementia. Inverse variance weighting (IVW) was used as the main statistical method. In addition, we explored whether cytokines act as a mediating factor in the pathway from gut microbiota to dementia. RESULTS: There were 20 positive and 16 negative causal effects between genetic liability in the gut microbiota and dementia. Also, there were five positive and four negative causal effects between cytokines and dementias. Cytokines did not act as mediating factors. CONCLUSIONS: Gut microbiota and cytokines were causally associated with five types of dementia, and cytokines seemed not to be the mediating factors in the pathway from gut microbiota to dementia.

[Correlation Between Initial Postoperative Hemoglobin Value and Prognosis in Non-Cardiac Surgery Patients Receiving Intraoperative Blood Transfusion].

Objective: To analyze the relationship between initial (within 24 hours) postoperative hemoglobin (Hb) value and prognosis in non-cardiac surgery patients receiving intraoperative blood transfusion, and to provide support for sensible blood use in surgery. Methods: A retrospective analysis was performed on all patients aged 18 or older who underwent non-cardiac surgeries and who received intraoperative blood transfusion at West China Hospital, Sichuan University from 2012 to 2018. According to their initial postoperative Hb levels, the patients were divided into 6 groups, including Hb<75 g/L, 75 g/L≤Hb<85 g/L, 85 g/L≤Hb<95 g/L, 95 g/L≤Hb<105 g/L, 105 g/L≤Hb<115 g/L, and Hb≥115 g/L goups. Multivariate linear regression was performed to examine the differences in the length-of-stay between the groups and binary logistic regression analysis was conducted to examine the differences between the groups in inpatient mortality, the rate of patient voluntary discharge against medical advice, incidence of acute ischemic injury, including acute kidney injury, myocardial infarction, and cerebral infarction, and length-of-stay longer than 28 days. In addition, the effects of multiple interactions between initial postoperative Hb and the types of surgery, the amount of intraoperative red blood cell infusion (red blood cell<8 U vs. red blood cell≥8 U), and preoperative anemia status (Hb<100 g/L vs. Hb≥100 g/L) on postoperative length-of-stay were analyzed. Results: A total of 7528 patients were included in this study. Compared to those of the reference group, the 95 g/L≤Hb<105 g/L group, the length-of-stay of patients with initial postoperative Hb<75 g/L increased and the mortality (odds ratio [ OR]=2.562) and the rate of voluntary discharge against medical advice ( OR=1.681) increased significantly. Patients in the 75 g/L≤Hb<85 g/L group had increased length-of-stay and increased incidence of acute ischemic injury ( OR=1.778) relative to the reference group. The interaction analysis showed that there was significant interaction between initial postoperative Hb and the types of surgery, which influenced the postoperative length-of-stay. Conclusion: In non-cardiac surgery patients who have receive blood transfusion, initial postoperative Hb<85 g/L is associated with poorer prognosis. However, those patients with higher initial postoperative Hb did not gain more benefits, suggesting that 85 g/L≤Hb<95 g/L may be the target Hb value for sensible intraoperative transfusion.