Hypoxic states are associated with abnormal proliferation and constriction of the smooth muscle cells surrounding the distal vessels of the lung. In hypoxic as well as in normal states, the endothelial cell layer may play a key role in controlling smooth muscle tone by secreting a number of vasoactive agents. Platelet-derived growth factor (PDGF), produced by endothelial cells, is a major growth factor for vascular smooth muscle cells and a powerful vasoconstrictor. It consists of a disulfide-linked dimer of two related peptides, A and B, that are products of two different genes. We found that hypoxic conditions (0-3% oxygen environments) significantly increased PDGF-B mRNA in cultured human umbilical vein endothelial cells by enhancing the transcriptional rate of this gene. This increase was inversely proportional to oxygen tension and was reversible upon reexposure of cells to a 21% oxygen atmosphere. mRNA levels of PDGF-A were not affected nor was the overall rate of cellular gene transcription increased in response to hypoxia. These studies indicate that endothelial cells are not only capable of sensing oxygen tension, but are also able to discriminate and respond to even small differences in oxygen tension resulting in dramatic upregulation of the PDGF-B chain gene. (J. Clin.

It is argued that analyses of subgroup differences utilizing a bivariate correlation strategy do not provide an adequate examination of test fairness. An analysis of differential prediction, which involves slopes and intercepts of regression lines results in more complete coverage of the test fairness issue, since the overall regression line determines the way in which a test is used for prediction. While subgroup correlation coefficients yield information concerning the slopes and intercepts, means and standard deviations must also be examined. A moderated multiple regression strategy is recommended as an alternative to separate analyses by subgroups. An ordered stepup regression procedure is presented which is more encompassing than the bivariate strategies, while avoiding inherent problems associated with subgroup coding in multiple regression.

Transcatheter interventions can be successfully performed in the early postoperative period. These procedures can have a positive impact on patient outcome; however, they should be performed only by a pediatric interventional cardiologist supported by a multi-disciplinary team.

Endothelial cells, including human umbilical vein endothelial cells (HUVEC), bovine aortic endothelial cells (BAEC), and bovine capillary endothelial cells (BCEC) in culture synthesize basic fibroblast growth factor (bFGF) and transforming growth factor type beta (TGF-beta). Basic FGF was cell-associated and synthesis was demonstrated by (i) the presence of bFGF mRNA species, (ii) binding to heparin-Sepharose and elution at 1.5 M NaCl, (iii) cross-reactivity with anti-bFGF antibodies when analyzed by electrophoretic blotting, and (iv) biological activity. Basic FGF was found in cell lysates at 2.3 ng/10(6) cells in HUVEC, 2.0 ng/10(6) cells in BCEC, and 13 ng/10(6) cells in BAEC. TGF-beta was secreted into media, and synthesis was demonstrated by (i) presence of TGF-beta mRNA species, (ii) cross-reactivity with anti-TGF-beta antibodies when analyzed by immunoprecipitation, (iii) competitive binding with authentic human platelet-derived TGF-beta that was blocked by TGF-beta specific blocking antibodies, and (iv) inhibition of [3H]TdR incorporation in CCl-64 cells. TGF-beta was secreted in an inactive form and required acid activation for detection. HUVEC synthesized 2.0 ng TGF-beta/10(6) cells per 12 hr; BCEC, 3.5 ng; and BAEC, 3.5 ng. HUVEC proliferation was not affected by treatment with exogenous TGF-beta, while BCEC proliferation was decreased by treatment with TGF-beta. Vascular endothelium is thus a source for these two potent multifunctional regulatory molecules, both of which may affect the growth of endothelium and neighboring fibroblasts, smooth muscle cells and white blood cells. The activation or release of these factors by endothelium may be a precipitating event in important cellular processes such as wound healing, organogenesis, and angiogenesis.

Initial postoperative serum lactate levels after pediatric open heart surgery may be predictive of outcome. Lactate levels are also higher in patients who go on to develop multiple organ system failure. Elevated postoperative lactate levels may reflect intraoperative tissue hypoperfusion, and measures aimed at increasing oxygen delivery, with normalization of lactate, may improve patient outcome.

A continuous incisional infusion of LA reduced postoperative analgesic requirement and sedative use in pediatric patients undergoing a median sternotomy incision. Dosed at a maximum rate of 0.4 mg x kg(-1) x h(-1), a continuous incisional infusion of LA is effective and safe for up to 72 h, with plasma levels of local anesthetic well below the toxic threshold.

Patients undergoing congenital heart surgery may occasionally require additional surgical procedures in the form of tracheostomy and gastrostomy. These procedures are often performed in an attempt to diminish hospital morbidity and length of stay. We reviewed the Web-based medical records of all patients undergoing congenital heart surgery at Miami Children's Hospital from February 2002 through August 2007. Patients who were deemed preterm and had undergone closure of a patent ductus arteriosis were eliminated. The records of all other patients were queried for the terms gastrostomy, g-tube, Nissan, fundal plication, tracheostomy, or tracheotomy. Patients' medical records in which these terms appeared in any portion were completely reviewed. There were 1660 congenital heart operations performed in the study period. There were 592 operations performed on patients whose age ranged from 1 month to 1 year and 441 neonatal operations. Mortality was 2%. Median postoperative stay was 8 days (range, 1-191 days), 12 days for neonates (range, 3-142 days), and 19 days for neonates undergoing RACHS-1 category 6 operations (range, 4-142 days). Tracheostomies were performed in four patients (0.2%). Gastrostomies were performed on eight patients (0.4%), representing 0.8% of patients <1 year of age, 1.4% of neonates, and 2.4% of patients undergoing RACHS-1 category 6 operations. The rate of patients undergoing either tracheostomy or gastrostomy after congenital heart surgery at our institution was quite low. Avoidance of either of these two procedures was achieved without increased morbidity or length of stay. The rate at which these procedures need to be performed may reflect the magnitude of the patients' lifetime trauma related to their underlying condition and acute and total surgical experiences.

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