Nitric oxide synthase (NOS) activity, an enzyme potentially involved in the major depressive episodes (MDE), could be indirectly measured by the L-Citrulline/L-Arginine ratio (L-Cit/L-Arg). The aim of this study was: (1) to compare the NOS activity of patients with a MDE to that of healthy controls (HC); (2) to assess its change after antidepressant treatment.

A total of 460 patients with a current MDE in a context of major depressive disorder (MDD) were compared to 895 HC for NOS activity (L-Cit/L-Arg plasma ratio). L-Arg and L-Cit plasma levels were measured using a MS-based liquid chromatography method. Depressed patients were assessed at baseline, and after 3 and 6 months of antidepressant treatment for depression severity and clinical response.

Depressed patients had a lower NOS activity than HC at baseline [0.31 ± 0.09 v. 0.38 ± 0.12; 95% confidence interval (CI) −0.084 to −0.062, p < 0.0001]. Lower NOS activity at baseline predicted a higher response rate [odds ratio (OR) = 29.20; 95% CI 1.58–536.37; p = 0.023]. NOS activity in depressed patients increased significantly up to 0.34 ± 0.08 after antidepressant treatment (Est = 0.0034; 95% CI 0.0002–0.0067; p = 0.03).

Depressed patients have a decreased NOS activity that improves after antidepressant treatment and predicts drug response. NOS activity may be a promising biomarker for MDE in a context of MDD.

The aim of this study was to assess the incidence of perioperative myocardial damage detected by serial measurements of troponin I after hip surgery and its association with late cardiovascular outcome.

Troponin I was measured during the first three postoperative days in 88 consecutive patients undergoing hip surgery. Values above the 99th percentile (0.08 ng mL−1) were considered positive. Major cardiac events (cardiac death, myocardial infarction and cardiac failure) were recorded during hospital stay and 1 yr after surgery.

Eleven patients (12.5%) exhibited elevated troponin I levels during hospital stay. Nine of them remained asymptomatic. During follow-up, 45% of them (5/11) suffered from a major cardiac event vs. 4% (3/76) for patients with normal postoperative troponin I levels (P = 0.0006). All-cause mortality rate was 36% (4/11) at 1 yr vs. 7% (5/71, P = 0.0131). Using multivariate Cox regression analysis adjusted for baseline data, independent factors associated with the occurrence of a cardiac event were troponin I elevation (OR=17.4 – CI 95% 3.7–82) and age (OR=1.1 yr−1 – CI 95% 1.01–1.21). Independent factors for all-cause mortality were troponin I elevation (OR=41.4 – CI 95% 5.4–320.4), and age (OR=1.3 yr−1 – CI 95% 1.1–1.4).

Troponin I release is common after hip surgery and is associated with a 10-fold increased incidence of long-term major cardiac events as compared to patients with normal troponin I levels (45% vs. 4%).