The effectiveness of growth hormone replacement on energy expenditure and body composition in patients with adult growth hormone deficiency.

Numerous studies have shown that growth hormone (GH) replacement in adult GH deficiency (AGHD) improves the body composition and metabolic rate; however, data about the relationship between body composition and energy expenditure in these patients is scarce. Our study aimed to investigate the changes in resting energy expenditure (REE) and body composition after GH replacement in patients with AGHD. We enrolled 15 patients diagnosed with AGHD and evaluated the effect of GH replacement administered once daily for 12 months on REE, body composition measured by bioelectrical impedance analysis, and serological markers. GH replacement therapy significantly increased the serum insulin growth factor-1 levels after 4, 8, and 12 months. The REE and REE/basal energy expenditure (REE/BEE) ratio significantly increased from 1278.0 ± 490.0 kcal/day and 0.87 ± 0.23 at baseline to 1505.5 ± 449.2 kcal/day and 1.11 ± 0.21 at 4 months, 1,918.7 ± 631.2 kcal/day and 1.29 ± 0.27 at 8 months, and 1,511.1 ± 271.2 kcal/day, 1.14 ± 0.29 at 12 months (p < 0.005, p < 0.005; p < 0.01, p < 0.01; p < 0.01, p < 0.005, respectively). There was no change in the body weight, while the lean body mass increased significantly from 45.8 ± 9.5 kg at baseline to 46.9 ± 9.4 kg at 4 months and 47.5 ± 10.1 kg at 8 months (p < 0.005, p < 0.01, respectively). The fat mass also decreased at 12 months. Lipid metabolism improved after 4 and 8 months. GH replacement therapy in patients with AGHD significantly improved the REE and body composition.

Identification of plasma binding proteins for glucose-dependent insulinotropic polypeptide.

Glucose-dependent insulinotropic polypeptide (GIP), secreted from enteroendocrine K cells, has potent insulin-releasing and extrapancreatic glucoregulatory activities. However, exogenous GIP has less potent biological effects compared with another incretin hormone, GLP-1, which limits its use for the treatment of type 2 diabetes. The fate and secretion of administered native GIP remain unclear. The aim of this study was to identify plasma binding proteins for human GIP. Fluorescent-labelled GIP was added to fresh human plasma and subjected to clear native polyacrylamide gel electrophoresis (CN-PAGE). Then fluorescent protein bands were in-gel trypsin-digested and subjected to liquid chromatography tandem-mass spectrometry (LC-MS/MS) analysis, revealing the presence of albumin, immunoglobulin G (IgG) and transferrin. In contrast to GIP, the binding of fluorescent GLP-1 and glucagon to plasma protein fractions were minimal. CN-PAGE analysis of synthetic GIP incubated with human serum albumin, purified IgG or transferrin, and subsequent western blot analysis revealed that GIP binds to each of these proteins. Taken together, these results indicate that GIP readily binds to albumin, IgG and transferrin, three plasma proteins highly abundant in the human peripheral circulation. Separation of protein complexes using CN-PAGE and the identification of in-gel digested proteins by LC-MS/MS analysis provide a promising strategy to identify plasma binding proteins for bioactive peptides.

Hemodialysis-Related Glycemic Disarray Proven by Continuous Glucose Monitoring; Glycemic Markers and Hypoglycemia.

OBJECTIVE: There is a high risk of asymptomatic hypoglycemia associated with hemodialysis (HD) using glucose-free dialysate; therefore, the inclusion of glucose in the dialysate is believed to prevent intradialytic hypoglycemia. However, the exact glycemic fluctuation profiles and frequency of asymptomatic hypoglycemia using dialysates containing >100 mg/dL glucose have not been determined. RESEARCH DESIGN AND METHODS: We evaluated the glycemic profiles of 98 patients, 68 of whom were men, with type 2 diabetes undergoing HD (HbA1c 6.4 ± 1.2%; glycated albumin 20.8 ± 6.8%) with a dialysate containing 100, 125, or 150 mg/dL glucose using continuous glucose monitoring. RESULTS: Sensor glucose level (SGL) showed a sustained decrease during HD, irrespective of the dialysate glucose concentration, and reached a nadir that was lower than the dialysate glucose concentration in 49 participants (50%). Twenty-one participants (21%) presented with HD-related hypoglycemia, defined by an SGL <70 mg/dL during HD and/or between the end of HD and their next meal. All these hypoglycemic episodes were asymptomatic. Measures of glycemic variability calculated using the SGL data (SD, coefficient of variation, and range of SGL) were higher and time below range (<70 mg/dL) was lower in participants who experienced HD-related hypoglycemia than in those who did not, whereas time in range between 70 and 180 mg/dL, time above range (>180 mg/dL), HbA1c, and glycated albumin of the two groups were similar. CONCLUSIONS: Despite the use of dialysate containing 100-150 mg/dL glucose, patients with diabetes undergoing HD experienced HD-related hypoglycemia unawareness frequently. SGL may fall well below the dialysate glucose concentration toward the end of HD.

Oxidised Met147 of human serum albumin is a biomarker of oxidative stress, reflecting glycaemic fluctuations and hypoglycaemia in diabetes.

Oxidative stress has been linked to a number of chronic diseases, and this has aroused interest in the identification of clinical biomarkers that can accurately assess its severity. We used liquid chromatography-high resolution mass spectrometry (LC-MS) to show that oxidised and non-oxidised Met residues at position 147 of human serum albumin (Met147) can be accurately and reproducibly quantified with stable isotope-labelled peptides. Met147 oxidation was significantly higher in patients with diabetes than in controls. Least square multivariate analysis revealed that glycated haemoglobin (HbA1c) and glycated albumin (GA) did not significantly influence Met147 oxidation, but the GA/HbA1c ratio, which reflects glycaemic excursions, independently affected Met147 oxidation status. Continuous glucose monitoring revealed that Met147 oxidation strongly correlates with the standard deviation of sensor glucose concentrations and the time spent with hypoglycaemia or hyperglycaemia each day. Thus, glycaemic variability and hypoglycaemia in diabetes may be associated with greater oxidation of Met147. Renal function, high-density lipoprotein-cholesterol and serum bilirubin were also associated with the oxidation status of Met147. In conclusion, the quantification of oxidised and non-oxidised Met147 in serum albumin using our LC-MS methodology could be used to assess the degree of intravascular oxidative stress induced by hypoglycaemia and glycaemic fluctuations in diabetes.

Methionine sulfoxides in serum proteins as potential clinical biomarkers of oxidative stress.

Oxidative stress contributes to the pathophysiology of a variety of diseases, and circulating biomarkers of its severity remains a topic of great interest for researchers. Our peptidomic strategy enables accurate and reproducible analysis of circulating proteins/peptides with or without post-translational modifications. Conventional wisdom holds that hydrophobic methionines exposed to an aqueous environment or experimental handling procedures are vulnerable to oxidation. However, we show that the mass spectra intensity ratio of oxidized to non-oxidized methionine residues in serum tryptic proteins can be accurately quantified using a single drop of human serum and give stable and reproducible results. Our data demonstrate that two methionine residues in serum albumin (Met-111 and Met-147) are highly oxidized to methionine sulfoxide in patients with diabetes and renal failure and in healthy smokers versus non-smoker controls. This label-free mass spectrometry approach to quantify redox changes in methionine residues should facilitate the identification of additional circulating biomarkers suitable for predicting the development or progression of human diseases.