Vagal activation alters prandial bile acid composition and glycemia in patients with hypoglycemia after Roux-en-Y gastric bypass surgery

BACKGROUND

Altered prandial glycemic response after Roux-en-Y gastric bypass (RYGB) is exaggerated in patients with post-RYGB hypoglycemia. Increased contribution of glucagon-like peptide 1 (GLP-1) to prandial insulin secretion plays a key role in developing hypoglycemia after RYGB, but the role of nonhormonal gut factors remains unknown. Here, the effect of vagal activation on prandial bile acid (BA) composition in relation to glucose, insulin and gut hormone responses was examined in a small size group of nondiabetic subjects after RYGB with intact gallbladder compared to nonoperated controls.

METHODS

Concentrations of blood glucose, hormones, and BAs were measured in two RYGB subjects with documented hypoglycemia (HGB), three asymptomatic RYGB-treated subjects (AGB), and four nonoperated controls with intact gallbladders during a meal-tolerance test with (MTT-Sham) and without (MTT) preceding modified sham feeding (chew and spit).

KEY RESULTS

Meal ingestion raised serum total BAs in RYGB-treated subjects without any effect in nonoperated controls. Modified sham feeding similarly increased meal-induced responses of conjugated BAs (CBAs) in all subjects (p < 0.05 compared to MTT alone), whereas unconjugated BAs (UBAs), mainly deoxycholic and chenodeoxycholic acid, were raised only in the HGB group (p < 0.001 for interaction). Prandial UBAs had an inverse correlation with glucose nadir (r = -0.75, p < 0.05) and were directly associated with ISR and GLP-1 during MTT-Sham.

CONCLUSIONS & INFERENCES

In this small cohort, vagal activation by modified sham feeding increases prandial CBAs in both operated and nonoperated subjects but enhances UBAs only in patients with documented post-RYGB hypoglycemia. Our findings highlight a potential role for nonhormonal gut factors, such as BA and gut microbiome, in glucose abnormalities after RYGB.

Effects of Nalbuphine on Gastrointestinal Function in Post-Operative Critical Ill Patients Admitted to the ICU: A Multicenter Randomized Controlled Trial

Background

Gastrointestinal (GI) function can be a significant problem in critically ill patients and is associated with detrimental outcomes. The administration of opioids for pain reduction is thought to contribute to GI dysfunction. We tested whether nalbuphine, a mixed agonist/antagonist opioid modulator, can promote GI recovery in postoperative critical patients admitted to the intensive care unit (ICU) and compared it with fentanyl, a selective mu opioid receptor (MOR) agonist.

Methods

This is a multicenter, single-blind, randomized controlled trial to investigate whether nalbuphine improves the GI recovery in ICU patients after surgery, and compared it with fentanyl. The primary outcome was the time to first defecation. Secondary outcomes included the use of sedatives, enemas or laxatives, the acute gastrointestinal injury (AGI) grade, the incidence of vomiting, and the lengths of ICU and hospital stays.

Results

We randomized 436 patients, and a total of 369 patients were included in the modified intention-to-treat population (mITT) (185 to the nalbuphine group and 184 to the fentanyl group). The baseline demographic characteristics of the two groups were comparable after randomization. There was no significant difference in the time to defecation between the two groups [hazard ratio (HR) 0.94, 95% CI 0.74–1.19, p = 0.62]. There was no significant difference in the secondary outcomes between the two groups.

Conclusion

We found no evidence that nalbuphine administration can improve the GI function in postoperative critical patients admitted to the ICU compared with fentanyl. However, the CI was wide and we could not exclude the clinically important difference.

Probiotics Improve Gastrointestinal Function and Life Quality in Pregnancy

We studied whether probiotics were beneficial for hormonal change-associated dysbiosis, which may influence the enteric nervous system and GI function during early pregnancy. The study was 16 days consisting of two cycles of six daily probiotics mainly Lactobacillus and 2 days without probiotics. Daily surveys were conducted to monitor GI function and life quality. A subset of the participants who contributed fecal specimens was used for microbiota metagenomic sequencing, metabolomics, and quantification of bacterial genes to understand potential underlying mechanisms. Statistical analyses were done by generalized linear mixed-effects models. Thirty-two obstetric patients and 535 daily observations were included. The data revealed that probiotic supplementation significantly reduced the severity of nausea, vomiting, constipation, and improved life quality. Moreover, a low copy number of fecal bsh (bile salt hydrolase), which generates free bile acids, was associated with high vomiting scores and probiotic intake increased fecal bsh. In exploratory analysis without adjusting for multiplicity, a low fecal α-tocopherol, as well as a high abundance of Akkemansia muciniphila, was associated with high vomiting scores and times, respectively. The potential implications of these biomarkers in pregnancy and GI function are discussed. Probiotics likely produce free bile acids to facilitate intestinal mobility and metabolism.

Effect of fecal microbiota transplantation on neurological restoration in a spinal cord injury mouse model: involvement of brain-gut axis

BACKGROUND

Spinal cord injury (SCI) patients display disruption of gut microbiome, and gut dysbiosis exacerbate neurological impairment in SCI models. Cumulative data support an important role of gut microbiome in SCI. Here, we investigated the hypothesis that fecal microbiota transplantation (FMT) from healthy uninjured mice into SCI mice may exert a neuroprotective effect.

RESULTS

FMT facilitated functional recovery, promoted neuronal axonal regeneration, improved animal weight gain and metabolic profiling, and enhanced intestinal barrier integrity and GI motility in SCI mice. High-throughput sequencing revealed that levels of phylum Firmicutes, family Christensenellaceae, and genus Butyricimonas were reduced in fecal samples of SCI mice, and FMT remarkably reshaped gut microbiome. Also, FMT-treated SCI mice showed increased amount of fecal short-chain fatty acids (SCFAs), which correlated with alteration of intestinal permeability and locomotor recovery. Furthermore, FMT downregulated IL-1β/NF-κB signaling in spinal cord and NF-κB signaling in gut following SCI.

CONCLUSION

Our study demonstrates that reprogramming of gut microbiota by FMT improves locomotor and GI functions in SCI mice, possibly through the anti-inflammatory functions of SCFAs. Video Abstract.