Redox-dependent and ligand-independent trans-activation of insulin receptor by globular adiponectin.

UNLABELLED: Adiponectin/ACRP30 is an adipose tissue-derived hormone with antiatherogenic, antidiabetic, and insulin-sensitizing properties. Although the metabolic effects of adiponectin on glucose and lipid metabolism are well known, the signaling pathways triggered by adiponectin receptors remain to be elucidated. We report evidence that in hepatic cells, adiponectin stimulation produces a transient burst of reactive oxygen species (ROS) through activation of the small GTPase Rac1 and 5-lypoxigenase. Furthermore, adiponectin-induced oxidants cause the oxidation/inhibition of protein-tyrosine phosphatase (PTP) 1B, one of the major phosphotyrosine phosphatases involved in the control of insulin receptor phosphorylation. Adiponectin causes increased association of PTP1B to insulin receptor and the oxidation/inhibition of the phosphatase, ultimately provoking the ligand-independent trans-phosphorylation of insulin receptor. We also report evidence that redox signaling plays a key role in both mitogen-activated protein kinase activation and hepatic glucose consumption induced by adiponectin. CONCLUSION: These results point to ROS as critical regulators of the cross-talk between adiponectin and insulin pathways and provide a redox-based molecular mechanism for the insulin-sensitizing function of adiponectin.

Phosphorylation of the neural cell adhesion molecule on serine or threonine residues is induced by adhesion or nerve growth factor.

The neural cell adhesion molecule (NCAM) is a member of the immunoglobulin superfamily and plays a crucial role during development and regeneration. It is expressed in three major isoforms; two of them with intracellular domains of different length and one without any intracellular domain. NCAM is known to be phosphorylated and contains up to 49 serine or threonine residues, which could be phosphorylated. However, the impact of NCAM phosphorylation is still unclear. Here we describe NCAM being phosphorylated during neuronal differentiation of PC12 cells. We provide evidence that protein kinase C is involved in the phosphorylation of NCAM. In agreement with our earlier observation that the protein phosphatase 1 is associated with NCAM, we additionally found that NCAM is a substrate for the protein phosphatase 1 but not for the protein phosphatase 2A.

Laparoscopy in patients over 60 years old: a prospective, randomized evaluation of laparoscopic versus open adnexectomy.

OBJECTIVE: To compare objective and subjective parameters of surgical stress following laparoscopic and open adnexectomy in patients older than 60 years old. STUDY DESIGN: Twenty patients with a benign ovarian tumour were prospectively randomized to undergo adnexectomy by a laparoscopic or an open surgical procedure. Measurements included C-reactive protein; interleukin-6 before, during, and after surgery; intensity and duration of postoperative pain; and complications and recovery period. Statistical analysis consisted of analysis of variance and a Mann-Whitney U test. RESULTS: The levels of the interleukin-6 and C-reactive protein differed significantly between the 2 operative procedures (P = .013) in favor of the laparoscopic approach. The laparoscopic approach was associated with a reduction in operative morbidity, postoperative pain, analgesic requirement, and recovery period. CONCLUSIONS: Minimally invasive surgery is of particular benefit to elderly patients if there is a plan in place for appropriate staging and treatment by laparotomy for malignancy. It should be the first choice and may help to reduce postoperative complications.