The effect of gender and gender match on mortality in pediatric heart transplantation.

The effect of organ-recipient gender match on pediatric heart transplant mortality is unknown. We analyzed the effects of gender and donor-recipient gender matching. Based on Organ Procurement and Transplant Network data, we performed a historical cohort study in a population of 3630 heart transplant recipients less than 18 years old. We compared unadjusted and adjusted mortality by recipient gender, donor gender and between gender-matched and gender-mismatched recipients. Female recipients had decreased survival compared to male recipients (unadjusted hazard ratio [HR] 1.16, confidence interval [CI] 1.02-1.31; p = 0.020). Organ-recipient gender mismatch did not affect mortality for either male or female recipients, though gender-mismatched females had the worst survival compared to gender-matched males, who had the best survival (unadjusted HR 1.26, CI 1.07-1.49; p = 0.005). After adjustment for other risk factors affecting transplant mortality, female recipients had decreased survival compared to male recipients (HR 1.27, CI 1.12-1.44; p = 0.020) and gender matching had no effect. In conclusion, gender mismatch alone did not increase long-term mortality for pediatric heart transplant recipients. However, there may be additive effects of gender and gender matching affecting survival. There are insufficient data at this time to support that recipient and donor gender should affect heart allocation in children.

Egr-1 is activated in endothelial cells exposed to fluid shear stress and interacts with a novel shear-stress-response element in the PDGF A-chain promoter.

Exposure of vascular endothelial cells to fluid mechanical forces can modulate the expression of many genes involved in vascular physiology and pathophysiology. Here, we report that platelet-derived growth factor (PDGF) A-chain gene expression is induced at the level of transcription in cultured bovine aortic endothelial cells exposed to a physiologic level of steady laminar shear stress (10 dyn/cm2). 5' Deletion analysis of the human PDGF-A promoter revealed that a GC-rich region near the TATA box was required for shear-inducible reporter gene expression. This element conferred shear inducibility onto a heterologous promoter-reporter construct that was otherwise unresponsive to shear stress. The induction of PDGF-A expression by shear was preceded by rapid and transient induction in the expression of the immediate-early gene, egr-1, which binds to GC-rich sequences. Gel shift studies indicated that shear-induced Egr-1 bound to the proximal PDGF-A promoter in a specific and time-dependent manner, displacing Sp1 from their overlapping recognition elements. Overlapping consensus binding sites for Egr-1 and Sp1 also appear in the proximal promoters of several other endothelial genes, including transforming growth factor-beta 1 and tissue factor, whose expression is modulated by shear stress. These findings define the Egr-1 binding site in the proximal PDGF-A promoter as a shear-stress-responsive element and suggest that shear-stimulated Egr-1 gene expression may be a unifying theme in the induction of various other endothelial genes exposed to biomechanical forces.

Early and persistent induction of monocyte chemoattractant protein 1 in rat cardiac allografts.

The early response gene for monocyte chemoattractant protein 1 (MCP-1) encodes a potent chemotactic factor that is specific for monocytes. To determine whether MCP-1 is involved in macrophage recruitment in cardiac allografts, we studied time-dependent MCP-1 gene and protein expression patterns in the heterotopic, Lewis to F-344 rat transplantation model (by reverse transcription-PCR and immunohistochemistry). There was a significant increase (8- to 12-fold) in MCP-1 gene transcripts in cardiac allografts compared with host hearts at 7, 14, and 28 days after transplantation. This induction was not observed with syngeneic transplants or hosts exposed to the same circulating cells and blood products. The MCP-1 gene product was expressed predominantly by mononuclear cells that double-stained with antimacrophage antibody (ED1) and localized to the interstitial and vascular spaces of the allografts. Immunocytochemical cell counting revealed significant increases in both MCP-1- and ED1-immunopositive cells in 7-, 14-, and 28-day allografts (in comparison with day 0 hearts). The absolute number of MCP-1-positive cells (5-7%) was lower than that of ED1-positive cells (25-34%) at all time points, suggesting that MCP-1-positive cells represent a subpopulation of activated macrophages. The persistent expression of MCP-1 in association with increased macrophage localization suggests that this inducible mediator contributes to the chronic inflammatory response following cardiac transplantation and that it may play a role in the pathogenesis of transplant arteriosclerosis.

Cloning and characterization of a sixth adenylyl cyclase isoform: types V and VI constitute a subgroup within the mammalian adenylyl cyclase family.

A sixth member of the mammalian adenylyl cyclase family has been isolated from a canine cardiac cDNA library. This isoform is more highly homologous to type V than to the other adenylyl cyclase types; sequence similarity is apparent even in the transmembrane regions where the greatest divergence among the types exists. Type VI mRNA expression is most abundant in heart and brain; however, unlike type V, a low level of expression is also observed in a variety of other tissues examined. Type VI adenylyl cyclase can be stimulated by NaF, guanosine 5'-[gamma-thio]triphosphate, and forskolin but not by Ca2+/calmodulin, whereas it is inhibited by adenosine and its analogues. Comparison of both their structural and biochemical properties suggests that types V and VI constitute a distinct subgroup of the mammalian adenylyl cyclase family.

Isolation and characterization of a novel cardiac adenylylcyclase cDNA.

A novel adenylylcyclase cDNA (type V) was isolated from a canine heart cDNA library. Northern blotting indicates that the expression of this message is most abundant in heart with a lesser amount in brain but is absent in a variety of other tissues including lung, kidney, skeletal muscle, lymphocyte, and testis. The putative protein product predicted from the cDNA sequence has the motif of tandem six-transmembrane spans separated by a large hydrophilic cytoplasmic loop as seen in other members of the adenylylcyclase family. When this protein is expressed using a CMT cell transient expression system, the adenylylcyclase activity was stimulated by NaF, GTP gamma S, and forskolin, but not by calmodulin. The activity was inhibited in a concentration-dependent manner with either P-site active agents such as adenosine or in the presence of calcium. These data indicate that the protein encoded by this cDNA is adenylylcyclase with the biochemical features characteristic of the cardiac isoform.