Anesthetic Considerations for the Obstetrical Patient with Aortic Valve Dysfunction

The issue examined 1·11 tl11· s paper 1· s aorti·c va1 v e dysfuncti·o n m· the pregnant pati·e nt, including anesthetic considerations during preinduction, induction, and postoperative phases. The examination of anesthetic considerations in pregnant patients with aortic valve dysfunction is important, because the anesthetist needs to: (a) be aware of the incidence of aortic dysfunction, (b) be knowledgeable regarding the pathophysiology involved in aortic dysfunction to assist in prompt and accurate treatment, (c) develop an appropriate anesthesia plan for the operating room, (d) be knowledgeable concerning the degree of dysfunction and use this knowledge in the assessment of the patient, and (e) be knowledgeable of common clinical implications of ao1iic dysfunction in pregnant patients. This paper presents materials related to the role of the nurse anesthetist in these five areas and concludes with recommendations for nursing research, policy, education, and practice. After a thorough discussion of the issues associated with aortic valve dysfunction and pregnancy, a quick reference tool will be provided to aid the anesthetist practicing in a high risk obstetrical area in determining appropriate anesthetic care for this patient populatio

Structure-function analysis of the essential islet regulatory factor Nkx2.2

The specification and differentiation of the pancreatic beta cell lineage requires guidance by spatiotemporally regulated signaling cues and a highly orchestrated set of transcription factors. Defining the factors and their regulatory functions that are required for proper beta cell development will enhance our ability to recapitulate these developmental events in vitro to generate beta cells from alternate cell sources. The homeodomain transcription factor Nkx2.2 is essential for pancreatic endocrine cell development; Nkx2.2-/- mice lack all beta cells and have reductions in alpha and pancreatic polypeptide (PP) cells. In place of these cell populations, the Nkx2.2-/- null islet is replete with ghrelin-producing epsilon cells. An Nkx2.2-repressor fusion protein derivative (Pdx1:Nkx2.2-EnR) expressed in the Nkx2.2-/- background can fully rescue the alpha cell population, but can only specify a few immature beta cells, suggesting that Nkx2.2 must contain both repressor and activator functions to properly guide beta cell development. Accordingly, Nkx2.2 has been shown to be an activator of several beta-cell targets. It has also been demonstrated that the corepressor Grg3 is expressed in the endocrine population and can physically interact with Nkx2.2, which points toward a mechanism by which Nkx2.2 confers transcriptional repression; however, the genes targeted by Nkx2.2/Grg3 are unknown. Additionally, how Nkx2.2 can both repress and activate genes in the same cellular context, and differentially regulate the same gene in different cellular contexts, is not understood. In this dissertation, I sought to determine the regulatory role of Nkx2.2 in the developing pancreas and its dependence on Grg interactions, and to elucidate whether post-translational modifications play a role in modulating Nkx2.2 regulatory activities. By analyzing mice carrying knock-in mutations in the Nkx2.2 Grg-interaction domain (Nkx2.2TNmut/TNmut), I show that the interaction between Nkx2.2 and Grg protein is required at two developmental stages of beta cell development: 1) Grg-mediated Nkx2.2 repression is necessary for correct beta-cell specification, and 2) the recruitment of Grg by Nkx2.2 is required to repress Arx in the beta cells to prevent beta-to-alpha cell reprogramming. Additionally, by analyzing the Nkx2.2TNmut/TNmut and Nkx2.2TNmut/TNmut;Ins:Cre;Arxfl/fl mice, I have identified several additional genes that may be regulated by Grg-mediated Nkx2.2 repression. Finally, I also present data to suggest that Nkx2.2 protein is phosphorylated, and that the phosphorylation state determines whether Nkx2.2 functions as an activator or a repressor in a promoter-specific context. These studies have begun to elucidate the complex regulatory roles that Nkx2.2 plays in specifying and maintaining the beta-cell lineage. Future analyses will help us to better understand the spatiotemporal regulatory activities that are required to make and maintain functional beta cells

Regulation of Neurod1 Contributes to the Lineage Potential of Neurogenin3+ Endocrine Precursor Cells in the Pancreas

During pancreatic development, transcription factor cascades gradually commit precursor populations to the different endocrine cell fate pathways. Although mutational analyses have defined the functions of many individual pancreatic transcription factors, the integrative transcription factor networks required to regulate lineage specification, as well as their sites of action, are poorly understood. In this study, we investigated where and how the transcription factors Nkx2.2 and Neurod1 genetically interact to differentially regulate endocrine cell specification. In an Nkx2.2 null background, we conditionally deleted Neurod1 in the Pdx1+ pancreatic progenitor cells, the Neurog3+ endocrine progenitor cells, or the glucagon+ alpha cells. These studies determined that, in the absence of Nkx2.2 activity, removal of Neurod1 from the Pdx1+ or Neurog3+ progenitor populations is sufficient to reestablish the specification of the PP and epsilon cell lineages. Alternatively, in the absence of Nkx2.2, removal of Neurod1 from the Pdx1+ pancreatic progenitor population, but not the Neurog3+ endocrine progenitor cells, restores alpha cell specification. Subsequent in vitro reporter assays demonstrated that Nkx2.2 represses Neurod1 in alpha cells. Based on these findings, we conclude that, although Nkx2.2 and Neurod1 are both necessary to promote beta cell differentiation, Nkx2.2 must repress Neurod1 in a Pdx1+ pancreatic progenitor population to appropriately commit a subset of Neurog3+ endocrine progenitor cells to the alpha cell lineage. These results are consistent with the proposed idea that Neurog3+ endocrine progenitor cells represent a heterogeneous population of unipotent cells, each restricted to a particular endocrine lineage

Human cardiac fibroblasts adaptive responses to controlled combined mechanical strain and oxygen changes in vitro

Upon cardiac pathological conditions such as ischemia, microenvironmental changes instruct a series of cellular responses that trigger cardiac fibroblasts-mediated tissue adaptation and inflammation. A comprehensive model of how early environmental changes may induce cardiac fibroblasts (CF) pathological responses is far from being elucidated, partly due to the lack of approaches involving complex and simultaneous environmental stimulation. Here, we provide a first analysis of human primary CF behavior by means of a multi-stimulus microdevice for combined application of cyclic mechanical strain and controlled oxygen tension. Our findings elucidate differential human CFs responses to different combinations of the above stimuli. Individual stimuli cause proliferative effects (PHH3+ mitotic cells, YAP translocation, PDGF secretion) or increase collagen presence. Interestingly, only the combination of hypoxia and a simulated loss of contractility (2% strain) is able to additionally induce increased CF release of inflammatory and pro-fibrotic cytokines and matrix metalloproteinases

Regulation of <em>Neurod1</em> Contributes to the Lineage Potential of Neurogenin3+ Endocrine Precursor Cells in the Pancreas

<div><p>During pancreatic development, transcription factor cascades gradually commit precursor populations to the different endocrine cell fate pathways. Although mutational analyses have defined the functions of many individual pancreatic transcription factors, the integrative transcription factor networks required to regulate lineage specification, as well as their sites of action, are poorly understood. In this study, we investigated where and how the transcription factors Nkx2.2 and Neurod1 genetically interact to differentially regulate endocrine cell specification. In an <em>Nkx2.2</em> null background, we conditionally deleted <em>Neurod1</em> in the Pdx1+ pancreatic progenitor cells, the Neurog3+ endocrine progenitor cells, or the glucagon+ alpha cells. These studies determined that, in the absence of Nkx2.2 activity, removal of <em>Neurod1</em> from the Pdx1+ or Neurog3+ progenitor populations is sufficient to reestablish the specification of the PP and epsilon cell lineages. Alternatively, in the absence of Nkx2.2, removal of <em>Neurod1</em> from the Pdx1+ pancreatic progenitor population, but not the Neurog3+ endocrine progenitor cells, restores alpha cell specification. Subsequent <em>in vitro</em> reporter assays demonstrated that Nkx2.2 represses <em>Neurod1</em> in alpha cells. Based on these findings, we conclude that, although Nkx2.2 and Neurod1 are both necessary to promote beta cell differentiation, Nkx2.2 must repress <em>Neurod1</em> in a Pdx1+ pancreatic progenitor population to appropriately commit a subset of Neurog3+ endocrine progenitor cells to the alpha cell lineage. These results are consistent with the proposed idea that Neurog3+ endocrine progenitor cells represent a heterogeneous population of unipotent cells, each restricted to a particular endocrine lineage.</p> </div

Neurod1 is expressed in a subset of endocrine progenitor cells.

<p>Utilizing the <i>Neurod1:LacZ</i> knock-in allele (<i>Neurod1^LacZ/+</i>) and immunofluorescence on tissues sections from E9.5 and E13.5 embryos, the expression pattern of Neurod1 (marked by beta-galactosidase; beta-gal) and glucagon (A, B), and Neurod1 and Neurog3 (C, D) was determined. DAPI marks all nuclei. All images are confocal. White bar indicates 50 microns. Boxes denote area magnified for inset, which are +1.75zoom of lower power image. Top and right rectangular panels represent a <i>Z</i> projection of at least 10 stack pictures at the level of intersection of the red/green crosshairs. (E) The percentage of each of the populations of glucagon+ cells, or (F) Neurog3+ cells was quantitated at E9.5 and E13.5. Data are represented as mean+/−SEM.</p

Nkx2.2 represses the <i>Neurod1</i> promoter in alphaTC1 cells.

<p>(A) Schematic representation of the <i>Neurod1</i> minimal promoter, with the areas previously identified to be activated by Nkx2.2 denoted with grey boxes. (B) Luciferase activity was assessed in alphaTC1 cells transfected with <i>Neurod1</i> promoter constructs (NDfull, NDΔ2, NDΔ3, NDΔ4) in addition to pcDNA3 alone or Nkx2.2. Nkx2.2-dependent activity was determined based on promoter region deletion. Luciferase activity was determined 48 hours post-transfection. Luciferase readings were normalized to <i>Renilla</i> luciferase values. (C) H3K4me3 is enriched in alpha and beta cells, although at significantly lower levels in alpha cells. The Nkx2.2 dephosphorylated mutant (S-11-A) results in a significant increase in H3K4me3 enrichment in alpha cells, comparable to levels observed in beta cell. Conversely, the Nkx2.2 phosphorylation mutant (S-11-D) results in a significant decrease in H3K4me3 in beta cells, comparable to levels in alpha cells. (D) The repressive H3K27me3 mark is not present on the <i>Neurod1</i> promoter in alpha or beta cells (<i>n</i> = 3). Data was normalized to <i>Gapdh.</i> All data are represented as mean+/−SEM. * p<0.05.</p