Biomedical subjects

Patricia Murray

Publications and source records attributed to Patricia Murray.

5 recordsLinked to original sources

PubMed2004

Distinct GATA6- and laminin-dependent mechanisms regulate endodermal and ectodermal embryonic stem cell fates.

This study investigates the establishment of alternative cell fates during embryoid body differentiation when ES cells diverge into two epithelia simulating the pre-gastrulation endoderm and ectoderm. We report that endoderm differentiation and endoderm-specific gene expression, such as expression of laminin 1 subunits, is controlled by GATA6 induced by FGF. Subsequently, differentiation of the non-polar primitive ectoderm into columnar epithelium of the epiblast is induced by laminin 1. Using GATA6 transformed Lamc1-null endoderm-like cells, we demonstrate that laminin 1 exhibited by the basement membrane induces epiblast differentiation and cavitation by cell-to-matrix/matrix-to-cell interactions that are similar to the in vivo crosstalk in the early embryo. Pharmacological and dominant-negative inhibitors reveal that the cell shape change of epiblast differentiation requires ROCK, the Rho kinase. We also show that pluripotent ES cells display laminin receptors; hence, these stem cells may serve as target for columnar ectoderm differentiation. Laminin is not bound by endoderm derivatives; therefore, the sub-endodermal basement membrane is anchored selectively to the ectoderm, conveying polarity to its assembly and to the differentiation induced by it. Unique to these interactions is their flow through two cell layers connected by laminin 1 and their involvement in the differentiation of two epithelia from the same stem cell pool: one into endoderm controlled by FGF and GATA6; and the other into epiblast regulated by laminin 1 and Rho kinase.

Basement Membrane↗

PubMed2004

The topographical regulation of embryonic stem cell differentiation.

The potential use of pluripotent stem cells for tissue repair or replacement is now well recognized. While the ability of embryonic stem (ES) cells to differentiate into all cells of the body is undisputed, their use is currently restricted by our limited knowledge of the mechanisms controlling their differentiation. This review discusses recent work by ourselves and others investigating the intercellular signalling events that occur within aggregates of mouse ES cells. The work illustrates that the processes of ES cell differentiation, epithelialization and programmed cell death are dependent upon their location within the aggregates and coordinated by the extracellular matrix. Establishment of the mechanisms involved in these events is not only of use for the manipulation of ES cells themselves, but it also throws light on the ways in which differentiation is coordinated during embryogenesis.

Animals↗

PubMed2004

Topography, stem cell behaviour, and organogenesis.

The fundamental problem of development is to explain how the progeny of a single cell, the fertilised egg, differentiates to form all the tissues of the body in the right place at the right time. It has only been during the last couple of years that the mechanisms and molecules mediating interactions between cells and tissues have begun to be delineated. This article reviews some of these recent studies. Sequences of topographically defined cellular interactions lead not only to the development of the body but also to the obvious and remarkable inference that the body more or less automatically builds itself.

Cell Differentiation↗

PubMed2002

Pulse rate and behavioral state correlates after auditory, tactile, visual, and vestibular intervention in drug-exposed neonates.

OBJECTIVE: Compare responses of nonexposed and drug-exposed newborns to auditory, tactile, visual, and vestibular (ATVV) intervention. STUDY DESIGN: Prospective design with random assignment of drug-exposed (N=45) and nonexposed (N=72) newborns to control and experimental groups. METHODS: Experimentals received 15 minutes of ATVV twice after birth. Infant behavioral state (IBS) and pulse rate (PR) were measured. RESULTS: The nonexposed and drug-exposed control groups (p=0.021) differed on the distribution of IBS yet no differences were noted between the two experimental groups. Nonexposed and drug-exposed experimentals experienced more alertness and less quiet sleep than controls (p<0.05). PR and IBS were significantly correlated for all but the drug-exposed control group (nonexposed control, r=0.938, p=0.006; nonexposed experimental, r=0.979, p=0.001; drug-exposed experimental, r=0.955, p=0.003). Within the combined (control+experimental) drug-specific groups, only polydrug-exposed infants demonstrated such a correlation (r=0.584, p=0.046). A significant correlation was also identified within the cocaine-exposed group for the experimentals only (r=0.992, p<0.001). CONCLUSION: The ATVV promoted normal physiologic and behavioral function.

Adult↗

PubMed2002

Low metal bioavailability in a contaminated urban site.

Bioavailability of Cd, Cu, Ni, Pb, and Zn in a metal-enriched railway yard in Montréal, Québec, Canada was assessed using metal speciation, plant uptake, and microbial assays. Metal speciation of extracted soil solutions was estimated using the Windmere Humic Aqueous Model. In soil solutions, free Cd, Ni, and Zn ions represented as much as 80%, 72%, and 62%, respectively, of the total dissolved metals. Copper and Pb were strongly bound by dissolved organic matter, and metal-fulvic acid complexes represented as much as 99% of the total dissolved metals. Three field-collected plant species (dandelion, bladder campion, and chicory) varied in their tendency to accumulate metals in either their leaves or roots. Chicory grown in the greenhouse had significantly higher metal bioconcentration factors than wild chicory. Although the site studied is considered to be contaminated, no metal pool, such as free ions or dissolved or total soil metals, consistently predicted metal uptake by potted chicory. Regression analysis revealed that soil total metal concentrations could adequately predict tissue accumulations of Cd, Ni, Pb, and Zn in bladder campion but only Cd and Zn in dandelion. Data from microbial assays also showed that the soil respiration was not affected by the metal contamination, but that nitrification was inhibited for the most contaminated soils. These results indicate that the metal bioavailability in the railway yard is low, but they also suggest that nitrogen cycling may be affected.

Asteraceae↗