The inhibitory action of protamine on human internal thoracic artery contractions: the effect of free hemoglobin

Objective: We investigated the mechanism of the protamine action and the effects of free hemoglobin on protamine-induced responses in endothelium-denuded and-intact human internal thoracic artery (ITA) rings precontracted with phenylephrine (PE) or high KCl. Methods: Samples of redundant ITA obtained from patients undergoing a coronary artery bypass graft surgery were cut into 3 mm wide rings and suspended in 20 ml organ baths. Isometric tension was continuously measured with an isometric force transducer connected to a computer-based data acquisition system. Results: Acetylcholine (Ach, 10⁻⁸–10⁻⁵ M) caused a concentration-dependent relaxation of PE-precontracted ITA rings. Free hemoglobin (0.1 and 0.5 μM) produced a concentration-dependent and significant decrease in sensitivity (pD₂) and maximal contractility (E_max) in response to Ach in PE-precontracted ITA rings (P<0.0001). Protamine (50–800 μg/ml), free hemoglobin (0.1 and 0.5 μM), nitric oxide (NO) blocker N^ω-nitro- -arginine methyl ester (L-NAME, 100 μM) or soluble guanylate cyclase inhibitor methylene blue (10 μM) administration did not cause a significant alteration on basal tonus of endothelium-intact or -denuded ITA rings. Protamine (50–800 μg/ml) induced concentration-dependent relaxation responses in ITA rings precontracted by either PE or high KCl. There was no difference in sensitivity or maximal response to protamine between the endothelium-intact and -denuded rings. Incubation of endothelium-intact or -denuded ITA rings with L-NAME or free hemoglobin or methylene blue did not cause a significant inhibition on relaxation responses to protamine. ITA ring contractions induced by stepwise addition of calcium to high KCl solution with no calcium were almost completely inhibited by protamine (P<0.0001). Conclusions: It was suggested that protamine induced relaxation responses in human ITA rings is not NO- or endothelium-dependent but seems to depend on the interactions of protamine with calcium influxes and/or calcium release from intracellular stores in this tissue.     

Management of severe hyperbilirubinemia in the newborn: adrenal hematoma revisited.

A 4-day-old male infant presented with complaints of jaundice on the third day of life. He was full-term and appropriate for gestational age and born to unrelated parents. All laboratory investigation tests were normal except total serum bilirubin of 27.4 mg/dl with a direct bilirubin 0.29 mg/dl. Abdominal and cranial ultrasonography (US) was performed on sixth day of life because of severe hyperbilirubinemia. Abdominal US revealed adrenal hematoma. Enclosed hematomas may cause significant unconjugated hyperbilirubinemia in absence of other high-risk conditions.     

Nitric oxide affects serum ferritin levels in children with iron deficiency

In iron deficiency, serum levels of ferritin decrease. The lack of iron has been thought to be the main factor in this decrease, but another potential factor is nitric oxide, which has been shown to affect ferritin metabolism in vitro. The aim of this study was therefore to evaluate in children with iron deficiency the relation of serum ferritin, nitric oxide degradation products (nitrate and nitrite), and endothelin-1, a protein closely related to nitric oxide function. A total of 80 children were included in the study (39 with iron deficiency, 41 controls). Serum levels of ferritin, nitrate, nitrite, and endothelin-1 were measured in all participants. In children with iron deficiency, nitrate and nitrite levels were significantly higher (p < .009 and .01, respectively). Also, serum ferritin was negatively correlated with serum levels of nitrate and nitrite (p = .034, r = -.254 for nitrate and p = .01, r = -.593 for nitrite). No statistical relationship was found between serum ferritin and endothelin-1.     

Aortoiliac kissing stents: long-term results and analysis of risk factors affecting patency.

PURPOSE: To present the early and long-term results of aortoiliac kissing stents implantation and evaluate the risk factors affecting patency. METHODS: The data were retrospectively reviewed on 68 patients (64 men; mean age 55+/-11, range 32-77) who underwent kissing stents implantation during a 12-year period. The majority of patients (64, 94%) had claudication; 4 patients had rest pain. All were smokers. There were bilateral or unilateral stenoses in 42 (62%) patients, and unilateral occlusion and contralateral stenosis in 26 (38%). Lesions were treated with simultaneous implantation of self-expanding (n=52) or balloon-expandable (n=16) stents. After the procedure, patency was determined with Doppler ultrasonography or angiography at 1, 3, 6, and 12 months and annually thereafter. Primary, assisted primary, and secondary patency rates were calculated with Kaplan-Meier analysis on an intention-to-treat basis, and risk factors affecting the patency rates were determined with the Cox regression analysis. RESULTS: All procedures were technically and clinically successful. Complications occurred in 12%, but none required surgery. The follow-up period was 35+/-31 months. Primary, assisted primary, and secondary patency rates, respectively, were 76%, 90%, and 94% at 1 year; 63%, 86%, and 92% at 3 years; and 63%, 64%, and 81% at 5 years. In multivariate analysis, age <50 years and presence of iliac occlusion were identified as risk factors for reduced primary and assisted primary patency; a crossed configuration of kissing stents was identified as a risk factor for reduced primary patency. CONCLUSION: Implantation of kissing stents is a safe and effective alternative in the treatment of aortoiliac obstructions. However, overall primary and assisted primary patency rates are inferior to those reported for surgery. Long-term patency comparable to surgery may be obtained in patients >50 years and in those without an iliac occlusion, particularly if a favorable stent configuration is achieved.