Effect of Right-Sided Versus Left-Sided Contrast Injection on Intra-arterial Opacification Characteristics of Head and Neck Computed Tomography Angiograms and Interactions With Patient Sex, Weight, and Cardiac Output.

OBJECTIVE: The aims of this study were to support the standard clinical assumption that preferential right-sided injection (RSI) over left-sided injection (LSI) results in improved head and neck computed tomography angiograms and to determine which patients most benefit from RSIs. METHODS: Head and neck computed tomography angiograms of 453 RSIs and 419 LSIs were included. Interactions between injection side, age, weight, body mass index, and left ventricular ejection fraction with mean vessel Hounsfield units (HU) were compared. Statistical analysis was performed using 2-tailed Student t tests, Mann-Whitney U tests, and simple linear (SL) and multiple linear regressions. RESULTS: Right-sided injection yielded higher HU for patients older than 40 years (eg, RSI of the right common carotid artery [RCCA] vs LSI of the RCCA; P < 0.01). Body mass index (eg, RCCA; r = -0.31, P < 0.01 [SL]) and weight (eg, RCCA; r = -0.39, P < 0.01 [SL]) were negatively correlated with HU. Female had higher HU (mean ± SE, +39.7 ± 7.6 HU; P < 0.01 [multiple linear]). Left ventricular ejection fraction had no interactions with injection side or HU. CONCLUSIONS: The findings support preferential RSI in patients older than 40 years with higher body mass index and weight, particularly male.

Stromal cell-derived factor-1 (SDF-1) signalling regulates human placental trophoblast cell survival.

Stromal cell-derived factor-1 (SDF-1 or CXCL12) is the physiologic ligand for the chemokine receptor CXCR4. CXCR4-mediated signalling regulates cell migration and apoptosis in certain haematopoietic and neuronal cells. Using gene profiling, we determined that CXCR4 is the only chemokine receptor for which mRNA expression is regulated during trophoblast differentiation in vitro. Based on the known effects of CXCR4 ligation, we hypothesized that CXCR4 activation may regulate placental trophoblast cell survival (i.e. protection from apoptosis), an important mechanism for the establishment and maintenance of the uteroplacental barrier. Human cytotrophoblasts (CTBs) were cultured in defined media and treated with graded doses of SDF-1 (10-100 ng/ml) or with an anti-CXCR4 neutralizing antibody. Exposure to anti-CXCR4 antibody reduced CTB cell numbers by 25-40%. Treatment with SDF-1 decreased the proportions of apoptotic terminal deoxynucleotidyl transferase-mediated dUTP-FITC nick-end labelling(+) cells (apoptotic index [AI] of 2.79+/-0.61% [control] versus 1.88+/-0.56% [SDF-1]; P<0.05) and caspase-activated cells (AI of 7.95+/-2.49% [control] versus 3.81+/-1.49% [SDF-1]; P<0.05). We determined that SDF-1 also activated the triple MAP Kinase isoforms ERK1/2 and p38 in trophoblasts. Immunocytochemistry confirmed SDF-1-induced nuclear translocation of phosphorylated ERK1/2. Blocking of ERK1/2 signalling with the specific inhibitor PD98059 reversed SDF-1-mediated inhibition of apoptosis (AI of 1.65+/-0.34 [SDF-1] versus 3.50+/-0.5 [SDF-1 + PD98059]; P<0.05), suggesting that SDF-1 acts through this pathway as a trophoblast survival factor. These results indicate that SDF-1/CXCR4 signalling stimulates anti-apoptotic pathways in cultured trophoblasts. This chemotactic ligand/receptor system may promote trophoblast survival during pregnancy. Alterations in SDF-1 and/or CXCR4 expression or function may be associated with specific pregnancy disorders.