PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-5 (5)
 

Clipboard (0)
None

Select a Filter Below

Journals
Year of Publication
Document Types
1.  Distinct Requirements for Cranial Ectoderm and Mesenchyme-Derived Wnts in Specification and Differentiation of Osteoblast and Dermal Progenitors 
PLoS Genetics  2014;10(2):e1004152.
The cranial bones and dermis differentiate from mesenchyme beneath the surface ectoderm. Fate selection in cranial mesenchyme requires the canonical Wnt effector molecule ╬▓-catenin, but the relative contribution of Wnt ligand sources in this process remains unknown. Here we show Wnt ligands are expressed in cranial surface ectoderm and underlying supraorbital mesenchyme during dermal and osteoblast fate selection. Using conditional genetics, we eliminate secretion of all Wnt ligands from cranial surface ectoderm or undifferentiated mesenchyme, to uncover distinct roles for ectoderm- and mesenchyme-derived Wnts. Ectoderm Wnt ligands induce osteoblast and dermal fibroblast progenitor specification while initiating expression of a subset of mesenchymal Wnts. Mesenchyme Wnt ligands are subsequently essential during differentiation of dermal and osteoblast progenitors. Finally, ectoderm-derived Wnt ligands provide an inductive cue to the cranial mesenchyme for the fate selection of dermal fibroblast and osteoblast lineages. Thus two sources of Wnt ligands perform distinct functions during osteoblast and dermal fibroblast formation.
Author Summary
Craniofacial abnormalities are relatively common congenital birth defects, and the Wnt signaling pathway and its effectors have key roles in craniofacial development. Wntless/Gpr177 is required for the efficient secretion of all Wnt ligands and maps to a region that contains SNPs strongly associated with reduced bone mass, and heterozygous deletion is associated with facial dysmorphology. Here we test the role of specific sources of secreted Wnt proteins during early stages of craniofacial development and obtained dramatic craniofacial anomalies. We found that the overlying cranial surface ectoderm Wnts generate an instructive cue of Wnt signaling for skull bone and skin cell fate selection and transcription of additional Wnts in the underlying mesenchyme. Once initiated, mesenchymal Wnts may maintain Wnt signal transduction and function in an autocrine manner during differentiation of skull bones and skin. These results highlight how Wnt ligands from two specific tissue sources are integrated for normal craniofacial patterning and can contribute to complex craniofacial abnormalities.
doi:10.1371/journal.pgen.1004152
PMCID: PMC3930509  PMID: 24586192
2.  Comparative gene expression analysis of avian embryonic facial structures reveals new candidates for human craniofacial disorders 
Human Molecular Genetics  2009;19(5):920-930.
Mammals and birds have common embryological facial structures, and appear to employ the same molecular genetic developmental toolkit. We utilized natural variation found in bird beaks to investigate what genes drive vertebrate facial morphogenesis. We employed cross-species microarrays to describe the molecular genetic signatures, developmental signaling pathways and the spectrum of transcription factor (TF) gene expression changes that differ between cranial neural crest cells in the developing beaks of ducks, quails and chickens. Surprisingly, we observed that the neural crest cells established a species-specific TF gene expression profile that predates morphological differences between the species. A total of 232 genes were differentially expressed between the three species. Twenty-two of these genes, including Fgfr2, Jagged2, Msx2, Satb2 and Tgfb3, have been previously implicated in a variety of mammalian craniofacial defects. Seventy-two of the differentially expressed genes overlap with un-cloned loci for human craniofacial disorders, suggesting that our data will provide a valuable candidate gene resource for human craniofacial genetics. The most dramatic changes between species were in the Wnt signaling pathway, including a 20-fold up-regulation of Dkk2, Fzd1 and Wnt1 in the duck compared with the other two species. We functionally validated these changes by demonstrating that spatial domains of Wnt activity differ in avian beaks, and that Wnt signals regulate Bmp pathway activity and promote regional growth in facial prominences. This study is the first of its kind, extending on previous work in Darwin's finches and provides the first large-scale insights into cross-species facial morphogenesis.
doi:10.1093/hmg/ddp559
PMCID: PMC2816616  PMID: 20015954
3.  Detection, evaluation, and management of preoperative anaemia in the elective orthopaedic surgical patient: NATA guidelines 
Previously undiagnosed anaemia is common in elective orthopaedic surgical patients and is associated with increased likelihood of blood transfusion and increased perioperative morbidity and mortality. A standardized approach for the detection, evaluation, and management of anaemia in this setting has been identified as an unmet medical need. A multidisciplinary panel of physicians was convened by the Network for Advancement of Transfusion Alternatives (NATA) with the aim of developing practice guidelines for the detection, evaluation, and management of preoperative anaemia in elective orthopaedic surgery. A systematic literature review and critical evaluation of the evidence was performed, and recommendations were formulated according to the method proposed by the Grades of Recommendation Assessment, Development and Evaluation (GRADE) Working Group. We recommend that elective orthopaedic surgical patients have a haemoglobin (Hb) level determination 28 days before the scheduled surgical procedure if possible (Grade 1C). We suggest that the patient's target Hb before elective surgery be within the normal range, according to the World Health Organization criteria (Grade 2C). We recommend further laboratory testing to evaluate anaemia for nutritional deficiencies, chronic renal insufficiency, and/or chronic inflammatory disease (Grade 1C). We recommend that nutritional deficiencies be treated (Grade 1C). We suggest that erythropoiesis-stimulating agents be used for anaemic patients in whom nutritional deficiencies have been ruled out, corrected, or both (Grade 2A). Anaemia should be viewed as a serious and treatable medical condition, rather than simply an abnormal laboratory value. Implementation of anaemia management in the elective orthopaedic surgery setting will improve patient outcomes.
doi:10.1093/bja/aeq361
PMCID: PMC3000629  PMID: 21148637
anaemia; blood transfusion; orthopaedic surgery; preoperative assessment; preoperative preparation
4.  Bovine aortic endothelial cells elaborate an inhibitor of the generation of lipopolysaccharide-stimulated human blood monocyte procoagulant activity. 
We examined the effect of bovine aortic endothelial cell culture supernatants upon the generation of procoagulant activity by human blood monocytes. Confluent endothelial monolayers were cultured for up to 96 h. At timed intervals, culture supernatants were collected and incubated for 5 h with lipopolysaccharide-stimulated human peripheral blood mononuclear cells. The procoagulant activity of mononuclear cell lysates was determined in a one-stage clotting assay. In five experiments, procoagulant activity with culture supernatant (time 0) was 2,294 +/- 761 U/ml (mean +/- SEM). Culture supernatants from endothelial cells incubated for 24-96 h strongly inhibited mononuclear cell generation of procoagulant activity. Indomethacin (10 microM) added to endothelial cells delayed the appearance of procoagulant inhibitor for 72 h. Bovine aortic smooth muscle cell culture supernatants did not inhibit procoagulant activity. The inhibitor was heat stable, effective at 1:50 dilution, soluble, and acid sensitive, with a molecular weight of less than 1,500. Further studies on subpopulations of mononuclear cells demonstrated that endothelial inhibitor selectively decreased the generation of monocyte procoagulant activity and interfered with T lymphocyte amplification of monocyte production of procoagulant activity. Thus, we have demonstrated that endothelial cells elaborate a potent inhibitor of monocyte procoagulant activity.
Images
PMCID: PMC425186  PMID: 6736253
5.  Synthesis and release of Hageman factor (Factor XII) by the isolated perfused rat liver. 
Journal of Clinical Investigation  1983;72(3):948-954.
The site of synthesis of Hageman factor (HF, Factor XII) has not been previously demonstrated with certainty. We have studied the production and release of HF in the isolated perfused rat liver and have compared rates of synthesis in this system with absolute rates of degradation measured in vivo. Rat livers, perfused for 5 h with a recycling fluid consisting of a perfluorochemical emulsion (Fluosol 43), were used to demonstrate a cumulative increase of HF in the perfusate as measured by a specific and sensitive radioimmunoassay. The rate of increase in the perfusate pool of HF during the final 4 h of perfusion yielded a mean synthetic rate of 3.5 micrograms/h per 100 g body wt, which was approximately 0.2% of the synthetic rate of albumin in the same system. The cumulative appearance of albumin and transferrin was linear after 1 h and calculated rates of synthesis were 2,012 micrograms/h per 100 g and 263 micrograms/h per 100 g body wt, respectively. De novo synthesis of HF was confirmed by demonstrating incorporation of [14C]lysine into specific immunoprecipitates of HF, and by the observations that both specific incorporation of labeled amino acid and net release of immunoassayable HF were inhibited by the administration of cycloheximide. Finally, it was evident that the rates of synthesis observed in the isolated perfused liver agreed closely with absolute rates of degradation of HF measured in vivo with 125I-rat HF (4.0 micrograms/h per 100 g). From these data we conclude that the liver is the principal site of synthesis of HF.
Images
PMCID: PMC1129260  PMID: 6411770

Results 1-5 (5)