Dr Darell Tupper-Carey
Description
Biomedical Research Study Title- An observational study measuring correlations between visceral adiposity and the plasma concentration profiles of immune and metabolic mediators during the stress response to major surgery. Study Locations-Ng Teng Fong General Hospital, National University Healthcare System, and Singapore Immunology Network, Singapore. Principal Investigator- Dr Darell Tupper-Carey Senior Consultant in Anaesthesiology. Research Aims-This observational study investigated the inter-relationships between measurements of visceral adipose tissue deposition and the plasma concentration profiles of inflammatory and metabolic mediators of the stress response to surgery. Study design was a prospective observational study of subjects undergoing total knee arthroplasty surgery. Measurements- Visceral adipose tissue (DEXA VAT) measurements were performed postoperatively using DEXA scanning. Laboratory investigations- venous blood specimens were sampled at the following times during the study period- sample A-preoperatively (fasting baseline), sample B-24 hours post-surgery and sample C-72 hours post-surgery. Plasma cytokine, chemokine and endocrine samples were analysed using Bio-Rad Human Cytokine 27plex (Cat: M500KCAF0Y) and Bio-Rad Human Diabetes 10plex (Cat: 171A7001M) assays. Changes in mediator concentrations between the venous sampling time points were also calculated. Mediator concentration changes B-A and C-B during the two periods of the study were assumed to approximate with the hyper-inflammatory and hypo-inflammatory phases of the surgical stress response. Statistical analysis- Spearman Rank correlations were calculated to identify relationships between the dataset measurements. Results- Total of 26 recruited subjects. Plasma concentrations of the adipokine visfatin/NAMPT were correlated with insulin concentrations (rho=0.749, adjusted p=0.003) and VAT deposition (rho=0.661, adjusted p=0.016) at 24 hrs following surgery. An inverse correlation was observed between the change in the concentration of insulin during the hyper-inflammatory and hypo-inflammatory phases of the stress response to surgery (rho=-0.912, adjusted p<0.001). Strong correlations were also observed between changes in concentration of insulin and the incretin hormone GIP during the hyper-inflammatory (rho=0.832, adjusted p<0.001) and the hypo-inflammatory (rho=0.735, adjusted p=0.008) phases of the stress response to surgery. Conclusions- Plasma insulin concentrations display highly regulated concentration profiles following surgery that are associated with visceral adiposity both at rest and during the peak of the stress response. These results indicate novel potential roles for visfatin/NAMPT and GIP in regulating insulin secretion following surgery.