SUMMARY Mammalian target of rapamycin (mTOR) activity is regulated by assembly of two functionally distinct complexes, mTORC1 and mTORC2. In syndecan-4 (S4) null endothelial cells, mTORC2 activity is reduced, resulting in decreased Akt activation, while mTORC1 activity is increased. Levels of rictor, mLST8, and mSin-1 are unchanged in total cell lysates but decreased in the rafts of S4−/− endothelial cells, as is the level of PKCα. Expression of myristoylated-PKCα in S4−/− cells restores rictor, mLST8, and mSin-1 presence in the rafts and rescues Akt phosphorylation. PKCα knockdown mimics the effect of S4 deletion on mTORC2 localization and Akt activation. Reduced mTORC2 activity in S4−/− endothelial cells results in decreased FOXO1/3a and eNOS phosphorylation, decreased endothelial cell size and increased arterial blood pressure in S4−/− mice. Thus, S4-dependent targeting of PKCα to the plasma membrane is required for recruitment of mTORC2 components to the rafts and Akt activation.

Background Existing publicly-reported readmission measures are condition-specific, representing < 20% of adult hospitalizations. An all-condition measure may better measure quality and promote innovation. Objective To develop an all-condition, hospital-wide readmission measure. Design Measure development Setting 4,821 US hospitals. Patients Medicare Fee for Service (FFS) beneficiaries ≥ 65 years. Measurements Hospital-level, risk-standardized unplanned readmissions within 30 days of discharge. The measure uses Medicare FFS claims and is a composite of five specialty-based risk-standardized rates for medicine, surgery/gynecology, cardiorespiratory, cardiovascular and neurology cohorts. We randomly split the 2007–2008 admissions for development and validation. Models were adjusted for age, principal diagnosis and comorbidity. We examined calibration in Medicare and all-payer data, and compared hospital rankings in the development and validation samples. Results The development dataset contained 8,018,949 admissions associated with 1,276,165 unplanned readmissions (15.9%). The median hospital risk-standardized unplanned readmission rate was 15.8 (range 11.6–21.9). The five specialty cohort models accurately predicted readmission risk in both Medicare and all-payer datasets for average risk patients but slightly overestimated readmission risk at the extremes. Overall hospital risk-standardized readmission rates did not differ statistically in the split samples (p=0.7 for difference in rank) and 76% of hospitals’ validation set rankings were within two deciles of the development rank (24% >2 deciles). Of hospitals ranking in the top or bottom deciles, 90% remained within two deciles (10% >2 deciles), and 82% remained within one decile (18% > 1 decile). Limitations Risk-adjustment was limited to that available in claims data. Conclusions We developed a claims-based hospital-wide unplanned readmission measure for profiling hospitals that produced reasonably consistent results in different datasets and was similarly calibrated in both Medicare and all-payer data. Primary funding source Centers for Medicare & Medicaid Services

Chronic hypoxic pulmonary hypertension (PH) is associated with vasoconstriction and structural remodeling of pulmonary vessels including narrowing of the arterial lumen and loss of distal functional arteries. To test whether lung overexpression of the angiogenic factor vascular endothelial growth factor (VEGF) is beneficial in hypoxic PH, recombinant adenovirus encoding the human VEGF 165 gene under the control of a cytomegalovirus promoter (Ad. VEGF) or control vector containing no gene in the expression cassette (Ad.Null) was administered intratracheally to rats. With Ad. VEGF (10(8) plaque-forming units [pfu]), VEGF protein was present in bronchoalveolar lavage fluid as early as 2 d and until 17 d after gene transfer, but was not detected in serum. Only small patchy areas of mononuclear cells without cell damage, edema, or hemorrhage were observed on lung histology with no significant change in lung permeability. In rats pretreated with Ad.VEGF (10(8) pfu) 2 d before a 2-wk exposure to hypoxia (10% O(2)), lower values versus Ad. Null-pretreated controls were found for pulmonary artery pressure (25 +/- 1 versus 30 +/- 2 mm Hg, P < 0.05), right ventricular over left ventricular-plus-septum weight (0.37 +/- 0.01 versus 0.47 +/- 0. 02, P < 0.001), normalized wall thickness of 50- to 200-microm vessels (P < 0.001), and muscularization of distal vessels (P < 0. 001). Pretreatment with Ad.VEGF (10(8) pfu) increased endothelial nitric oxide synthase activity in lung tissue and partially restored endothelium-dependent vasodilation in isolated lungs from chronically hypoxic rats, as assessed by improvement of ionophore A23187-induced vasodilation and attenuation of endothelin-1 (300 pmol)-induced vasoconstriction, an effect abolished in the presence of nitro-L-arginine methylester. We conclude that adenoviral-mediated VEGF overexpression in the lungs attenuates development of hypoxic PH, in part by protecting endothelium-dependent function.

Vascular endothelial growth factor (VEGF) is an endothelial cell-specific mitogen that is upregulated during exposure to hypoxia. In this study, we analyzed heart and lung VEGF mRNA expression and examined pulmonary vascular remodeling as well as myocardial capillary density in two rat models of pulmonary hypertension involving exposure to chronic hypoxia (CH) and treatment with monocrotaline (MCT), respectively. The rats were studied after 0.5, 1, 3, 15, and 30 days of exposure to 10% O2 or 1, 6, and 30 days after a subcutaneous MCT injection (60 mg/kg). Both CH and MCT induced pulmonary hypertension and hypertrophy of the right ventricle (RV) with increased RV weight and atrial natriuretic peptide mRNA expression. VEGF mRNA expression as assessed by Northern blot analysis was potently induced after 12 h of hypoxia in both the right and left ventricles. After prolonged exposure to hypoxia, VEGF mRNA returned to baseline in the left ventricle (LV) but remained increased in the RV, where it peaked after 30 days. In MCT rats, VEGF mRNA was unchanged in the LV but decreased by 50% in the RV and by 90% in the lungs after 30 days. VEGF mRNA remained unchanged in the lungs from CH rats. Pulmonary vascular remodeling was more pronounced in MCT than in CH rats. The number of capillaries per RV myocyte was increased in rats exposed to 30 days of hypoxia, whereas it remained unchanged in MCT rats despite a similar degree of RV hypertrophy. Our results suggest that the sustained increase in VEGF expression in the hypertrophied RV during CH may account for the increased number of capillaries per myocyte. In contrast, reduced VEGF expression in the lungs and RV of MCT rats may aggravate pulmonary vascular remodeling and compromise RV myocardial perfusion.

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Abstract-Endothelial nitric oxide synthase (eNOS) plays an important role in control of vascular tone and angiogenesis among other functions. Its regulation is complex and has not been fully established. Several studies have emphasized the importance of phosphorylation in the regulation of eNOS activity. Although it is commonly accepted that protein kinase C (PKC) signaling inhibits eNOS activity by phosphorylating Thr 497 and dephosphorylating Ser 1179 , the distinct role of different PKC isoforms has not been studied so far. The PKC family comprises roughly 12 different isozymes that activate distinct downstream pathways. The present study was designed to investigate the role of PKC␣ isoform in regulation of eNOS activity. Overexpression of PKC␣ in primary endothelial cells was associated with increased eNOS-Ser 1179 phosphorylation and increased NO production. Inhibition of PKC␣ activity either by siRNA transfection or by overexpression of a dominant negative mutant resulted in a marked decrease in FGF2-induced Ser 1179 phosphorylation and NO production. In vivo, PKC␣ transduction in rat femoral arteries resulted in a significant increase in the resting blood flow that was suppressed by treatment with L-NAME, an eNOS inhibitor. In conclusion, these data demonstrate for the first time that PKC␣ stimulates NO production in endothelial cells and plays a role in regulation of blood flow in vivo.

Focal vascular injury and impaired endothelial function are features of pulmonary hypertension (PH) that lead to enhanced platelet endothelial cell interactions. Vascular endothelial growth factor (VEGF) is contained in platelets and released at sites of vascular injury to promote endothelial repair and wound healing in combination with platelet-derived nonspecific mitogens such as platelet-derived growth factor (PDGF). The overall balance between platelet VEGF and PDGF was investigated in 21 patients with primary PH, 8 with secondary PH, and 27 with chronic hypoxemic lung disease (CHLD), as well as in 29 control subjects. Platelet VEGF content was increased in patients with primary and secondary PH as compared with control subjects (518 +/- 89, 675 +/- 156, and 166 +/- 29 fg/10(5) platelets, respectively; p < 0.01), whereas platelet PDGF content was similar in the three groups (31 +/- 2, 36 +/- 4, and 33 +/- 3 pg/10(5) platelets, respectively; NS). Patients treated with a continuous prostacyclin infusion had a higher platelet VEGF but a similar platelet PDGF content as compared with untreated patients. Moderate increases in platelet VEGF and PDGF contents were observed in the CHLD patients. We conclude that patients with primary or secondary PH have an increase in platelet VEGF content, but not in platelet PDGF content, and that their platelet VEGF content increases further in response to prostacyclin infusion. We suggest that imbalance between platelet VEGF and PDGF is beneficial to patients with PH.

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