Nitric oxide-independent inhibitory effects of L-arginineanalog NG-monomethy-L-arginine on the generation of interleukin-2 activated cytotoxic activity in humans

Asymmetric dimethylarginine positively modulates calcium-sensing receptor signalling to promote lipid accumulation

Asymmetric dimethylarginine (ADMA) is generated through the irreversible methylation of arginine residues. It is an independent risk factor for cardiovascular disease, currently thought to be due to its ability to act as a competitive inhibitor of the nitric oxide (NO) synthase enzymes. Plasma ADMA concentrations increase with obesity and fall following weight loss; however, it is unknown whether they play an active role in adipose pathology. Here, we demonstrate that ADMA drives lipid accumulation through a newly identified NO-independent pathway via the amino-acid sensitive calcium-sensing receptor (CaSR). ADMA treatment of 3 T3-L1 and HepG2 cells upregulates a suite of lipogenic genes with an associated increase in triglyceride content. Pharmacological activation of CaSR mimics ADMA while negative modulation of CaSR inhibits ADMA driven lipid accumulation. Further investigation using CaSR overexpressing HEK293 cells demonstrated that ADMA potentiates CaSR signalling via G_q intracellular Ca²⁺ mobilisation. This study identifies a signalling mechanism for ADMA as an endogenous ligand of the G protein-coupled receptor CaSR that potentially contributes to the impact of ADMA in cardiometabolic disease.

Metabolic effects of adjuvant recombinant human growth hormone in patients with continuing sepsis receiving parenteral nutrition

BACKGROUND

Adjuvant growth hormone is advocated for treating the catabolism of prolonged sepsis not corrected by parenteral nutrition alone.

METHODS

An open study was performed in which eight patients whose postabsorptive resting energy expenditure was persistently elevated by a mean of 19% as a result of continuing sepsis were randomized to receive 0.03 or 0.06 mg/kg recombinant human growth hormone (rhGH) each evening for 7 days adjuvant to total parenteral nutrition. Plasma concentrations of growth hormone, insulin, insulin-like growth factors 1 and 2 (IGF-1 and -2) and their binding proteins IGFBP-1 and -3 were measured before and after rhGH, and their relationship with rates of whole-body protein turnover was determined in the morning in the postabsorptive state by using L-[1-13C]leucine.

RESULTS AND CONCLUSIONS

Before rhGH, the patients were hyperinsulinemic (mean, 44.4 mU/L) but had growth hormone levels within the normal range (< 10 mU/L). After the seventh dose of rhGH, nocturnal growth hormone concentrations rose to a mean of 35.3 +/- 26.1 and 61.3 +/- 21.05 mU/L for the low and higher dose groups, respectively. Morning IGF-1 concentrations showed a small increase during treatment, rising from a mean of 241.3 +/- 99.0 to 301.7 +/- 167.3 ng/mL for the low-dose group and from 214.5 +/- 74.6 to 294.1 +/- 116.9 ng/mL for the higher-dose group. IGF-2 increased slightly by 89 +/- 39 and 75 +/- 49 ng/mL for the low and higher doses, respectively. IGFBP-1 and -3 and insulin did not change. The balance between nitrogen input and urinary urea nitrogen increased after rhGH by a mean of 5.3 g/d with no differences between the two dosage groups (4.74 +/- 1.56 g/d for the higher dose, 5.94 +/- 3.70 g/d for the lower). No significant changes were observed in whole-body protein turnover after a 1-week course of rhGH.