Human GIP ELISA Kit

The objectives of this trial were to evaluate the association between corn processing, glucose-dependent insulinotropic polypeptide (GIP) concentration, and intramuscular (IM) fat deposition. We hypothesized that steers fed whole shelled corn (WSC) would have a greater IM fat deposition than steers fed cracked corn (CC) due to an increase in plasma GIP concentration. Backgrounded, Angus-cross cattle (initial body weight [BW] = 279 +/- 9.8 kg) were used in a randomized complete block design in a feedlot setting for an average of 230 d. Cattle were allotted in 12 pens (6 pens per treatment with 8 animals per pen). There were three blocks: heifers (n = 32, initial BW = 265 +/- 1.3 kg), small steers (n = 32, initial BW = 262 +/- 1.3 kg), and large steers (n = 32, initial BW = 310 +/- 1.4 kg). Two pens within each block were randomly assigned to one of the following treatments: 1) CC or 2) WSC. Animal growth performance, carcass characteristics, and plasma hormone and metabolite concentrations were analyzed using the MIXED procedure of SAS, including the fixed effects of treatment, or treatment, time, and their interaction. Pen and block were included as random effects. Carcass yield and quality grade distributions were compared using the GLIMMIX procedure of SAS. including the fixed effects of treatment and time with pen and block as random effects. Linear regression was used to evaluate the association of plasma GIP concentration and IM fat content. Average daily gain (P = 0.57) and final BW (P = 0.34) were similar, regardless of treatment. Cattle fed CC had reduced (P < 0.01) dry matter intake (DMI) when compared with those fed WSC. This lesser DMI resulted in improved gain:feed ratio (P < 0.01) for cattle fed CC compared with cattle fed WSC. There was no effect (P <= 0.33) of corn processing on plasma glucose, plasma GIP concentrations, hot carcass weight, dressing percentage, or marbling score. There was a positive linear relationship (P = 0.03) between IM fat concentration and plasma GIP concentration. In conclusion, feeding CC increased gain:feed ratio compared with WSC, but there was no difference in plasma GIP concentration, whereas plasma GIP concentration appears to be related to IM fat deposition.

Individual amino acids, amino acid mixtures and protein hydrolysates stimulate glucose uptake in many experimental models. To replicate better in vitro the dynamic postprandial response to feeding in vivo, in the present study we investigated the effects of culture media conditioned with fasted and postprandial human serum on GLUT4 translocation in L6-GLUT4myc myotubes. Serum samples were collected from healthy male participants (n = 8) at baseline (T0), 60 (T60) and 120 min (T120) after the ingestion of 0.33 g (kg body mass)(-1) of intact (WPC) or hydrolysed (WPH) whey protein and an isonitrogenous non-essential amino acid (NEAA) control. L6-GLUT4myc myotubes were starved of serum and amino acids for 1 h before incubation for 1 h in medium containing 1% postprandial human serum, after which GLUT4 translocation was determined via colorimetric assay. Medium conditioned with fasted human serum at concentrations of 5-20% increased cell surface GLUT4myc abundance. Incubation with serum collected after the ingestion of WPH increased cell surface GLUT4myc at T60 relative to T0 [mean (lower, upper 95% confidence interval)]; [1.13 (1.05, 1.22)], whereas WPC [0.98 (0.90, 1.07)] or NEAA [1.02 (0.94, 1.11)] did not. The differential increases in cell surface GLUT4myc abundance were not explained by differences in serum concentrations of total, essential and branched-chain amino acids or insulin, glucagon-like peptide 1 (GLP-1) and gastric inhibitory polypeptide (GIP). Using a new ex vivo, in vitro approach, cell culture medium conditioned with postprandial serum after the ingestion of a whey protein hydrolysate increased GLUT4 translocation in skeletal muscle cells.