A central role for CD68(+) macrophages in hepatopulmonary syndrome. Reversal by macrophage depletion.

RATIONALE: The etiology of hepatopulmonary syndrome (HPS), a common complication of cirrhosis, is unknown. Inflammation and macrophage accumulation occur in HPS; however, their importance is unclear. Common bile duct ligation (CBDL) creates an accepted model of HPS, allowing us to investigate the cause of HPS. OBJECTIVES: We hypothesized that macrophages are central to HPS and investigated the therapeutic potential of macrophage depletion. METHODS: Hemodynamics, alveolar-arterial gradient, vascular reactivity, and histology were assessed in CBDL versus sham rats (n = 21 per group). The effects of plasma on smooth muscle cell proliferation and endothelial tube formation were measured. Macrophage depletion was used to prevent (gadolinium) or regress (clodronate) HPS. CD68(+) macrophages and capillary density were measured in the lungs of patients with cirrhosis versus control patients (n = 10 per group). MEASUREMENTS AND MAIN RESULTS: CBDL increased cardiac output and alveolar-arterial gradient by causing capillary dilatation and arteriovenous malformations. Activated CD68(+)macrophages (nuclear factor-κB+) accumulated in HPS pulmonary arteries, drawn by elevated levels of plasma endotoxin and lung monocyte chemoattractant protein-1. These macrophages expressed inducible nitric oxide synthase, vascular endothelial growth factor, and platelet-derived growth factor. HPS plasma increased endothelial tube formation and pulmonary artery smooth muscle cell proliferation. Macrophage depletion prevented and reversed the histological and hemodynamic features of HPS. CBDL lungs demonstrated increased medial thickness and obstruction of small pulmonary arteries. Nitric oxide synthase inhibition unmasked exaggerated pulmonary vasoconstrictor responses in HPS. Patients with cirrhosis had increased pulmonary intravascular macrophage accumulation and capillary density. CONCLUSIONS: HPS results from intravascular accumulation of CD68(+)macrophages. An occult proliferative vasculopathy may explain the occasional transition to portopulmonary hypertension. Macrophage depletion may have therapeutic potential in HPS.

Semiconductor laser phase-noise cancellation using an electrical feed-forward scheme.

We demonstrate the reduction of semiconductor laser phase noise by using an electrical feed-forward scheme. We have carried out proof-of-concept experiments on a commercially available distributed-feedback laser emitting at the 1550 nm communication band. The preliminary results show more than 20 times reduction in the phase-noise power spectrum. The feed-forward scheme does not have the limited bandwidth, stability, and speed issues that are common in feedback systems. Moreover, in the absence of electronic noise, feed-forward can completely cancel the close-in phase noise. In this scheme, the ultimate achievable phase noise will be limited by the electronics noise. Using the proposed feed-forward approach, the linewidth of semiconductor lasers can be reduced by 3-4 orders of magnitude in a monolithic approach using today's low-noise scaled transistors with terahertz gain-bandwidth product.

Impact of drug eluting stent length on outcomes of percutaneous coronary intervention (from the EVENT registry).

In randomized trials, longer drug-eluting stent (DES) length has been associated with adverse clinical events. We used data from the EVENT registry to examine the impact of DES length on outcomes in routine clinical practice. We identified 5,425 unselected consecutive patients from the EVENT registry who had a single vessel treated with DES for nonemergency indications from 2004 through 2007. The association between stented length and short- and long-term outcomes was analyzed in ordinal categories (<15, 15 to 19, 20 to 24, and >24 mm) and as a continuous variable. There were few differences in baseline characteristics across categories. At 1 year, there was a stepwise increase in major adverse cardiac events (composite of death, myocardial infarction [MI], and target lesion revascularization [TLR]) with increasing stent length (8.0%, 10.1%, 11.8%, and 14.8%, p <0.001) and a similar relation with TLR (3.0%, 3.1%, 3.3%, and 5.0%, p = 0.02). After adjusting for demographic, clinical, angiographic, and treatment characteristics, longer stent length remained associated with 1-year major adverse cardiac events (adjusted hazard ratio 1.17 per 10-mm increase stent length) and TLR (hazard ratio 1.20 per 10 mm), but not with stent thrombosis. In conclusion, longer DES length is associated with increased adverse events, predominantly periprocedural MI, but also an increased rate of TLR.

Inability of intracoronary stenting to provide long-term relief for coronary compression secondary to chronic constrictive pericarditis.

Chronic constrictive pericarditis can result in extrinsic compression of coronary arteries during diastole. We present one such case wherein the coronary compression and the resultant cardiac ischemia developed late after surgical pericardiectomy, and treatment with intracoronary stenting was unsuccessful. Issues pertaining to management of this rare condition are discussed and a case made for surgical treatment for such patients.