Specific glucocorticoid binding in human uterine tissues, placenta and fetal membranes

The binding of [3H]dexamethasone to cytosol fractions of human myometrium, endometrium, decidua, chorion, amnion and placenta has been studied. All tissues examined contained high affinity, low capacity binding sites with high specificity for glucocorticoids. Maximum specific binding of [3H]dexamethasone was reached after about 10 h at 0-4 degrees C and remained stable for at least the next 12 h. Sucrose density gradient analysis showed that the binding macromolecules sedimented at 7.9 S in hypotonic solutions and at 4.35 in solutions containing 0.4 M KCl. In the presence of sodium molybdate, the sedimentation coefficients shifted both in the absence and presence of 0.4 M KCl to 8.9 and 5.7 S, respectively. The apparent equilibrium dissociation constants (Kd) of the glucocorticoid binding sites were similar in most tissues, ranging between 1 and 6 nM, with the exception of the placenta in which the binding sites showed a higher Kd (13-22 nM). In all tissues studied, the binding affinities were similar in nonpregnant and pregnant patients and in patients at different stages of pregnancy or in labor. The concentration of the binding sites in the different tissues ranged from 11 to 268 fmol/mg protein, higher concentrations being found in myometrium, placenta and amnion and lower concentrations found in endometrium, chorion and decidua. The number of binding sites was higher in the myometrium of nonpregnant than pregnant women, but was similar in the myometrium of women at term pregnancy before or during labor. In the placenta, the number of binding sites increased significantly from early pregnancy to midpregnancy, while in chorion, amnion and decidua the number of binding sites did not change during pregnancy. It is concluded that human uterine tissues, placenta and fetal membranes contain specific binding sites with properties characteristic of glucocorticoid receptors suggesting that these tissues may respond directly to glucocorticoids.     

Mediation of pinocytosis in cultured arterial smooth muscle and endothelial cells by platelet-derived growth factor

Pinocytosis was measured in monkey aortic smooth muscle cells (SMC), bovine aortic endothelial cells, and Swiss 3T3 cells in culture as cellular uptake of [U-(14)C]sucrose and horseradish peroxidase (HRP) from the tissue culture medium. Monkey arterial SMC and Swiss 3T3 cells were maintained in a quiescent state of growth at low cells density in medium containing 5 percent monkey plasma-derived serum (PDS). Replacement of PDS with 5 percent monkey whole blood serum (WBS) from the same donor, or addition to PDS of partially purified platelet-derived growth factor(s) (PF), resulted in a marked stimulation of pinocytosis as well as of cellular proliferation. In SMC, enhancement of the rate of pinocytosis occurred 4-6 h after exposure to WBS or PF, and the rate was up to twofold higher than the rate in medium containing PDS. In contrast, [(3)H]thymidine uptake by SMC did not increase until 12-16 h after exposure to PF. In endothelial cells the presence of PF or WBS did not enhance either the rate of pinocytosis or the rate of proliferation over that in PDS. Thus, endothelial cells did not become quiescent at subconfluent densities in PDS but maintained rates of proliferation and pinocytosis that were equivalent to those in WBS. By autoradiography, the fraction of labeled nuclei in SMC cultures 24 h after change of medium increased from 0.061 +/- 0.004 in quiescent cultures to 0.313 +/- 0.028 after exposure to WBS or PF. In contrast, labeling indices of endothelial cells were similar for cultures grown in PDS, WBS, or PF at any single time point after change of medium. These findings suggest that the rate of pinocytosis maybe be coupled in some fashion to growth regulation, which may be mediated in part by specific growth factors, such as that derived from the thrombocyte.     

Identification and ontogeny of beta-adrenergic receptors in fetal rabbit lung

High affinity (Kd=0.2 nM), low capacity (48 fmoles per mg protein), stereospecific binding sites, with properties characteristic of the β₁-subtype of β-adrenergic receptors, have been detected in fetal rabbit lung membranes as early as the 22nd day of gestation. The concentration of the receptor did not change significantly between the 22nd and 26th day of gestation, but increased 3-fold between the 26th and 29th day, reaching a level of 198 fmoles per mg protein. A further increase (from 198 to 315 fmoles per mg protein) in receptor concentration was observed in adult female rabbits. The increase in the levels of pulmonary β-adrenergic receptors between the 26th and 29th day of gestation is temporally related to the increase in surfactant release into the alveolar spaces of the fetal lung. Thus β-adrenergic agonists may act directly on the fetal lung to regulate surfactant secretion.     

Glucocorticoid receptors in lung. Comparison between nonactivated and activated forms of the cytoplasmic glucocorticoid binding protein and their relationship to the nuclear binding protein of fetal rabbit lung.

In the absence of salt the cytoplasmic glucocorticoid receptor of fetal rabbit lung sediments at 7 S while the nuclear receptor sediments at 4 S. However, if nuclear extracts are mixed with receptor-depleted cytosol preparations in dilute buffer solutions without added salt, the nuclear 4 S receptor sediments as a 7 S species similar to that observed for the cytoplasmic form under the same conditions suggesting an interaction of the nuclear receptor with other cytosol proteins rather than with itself. In addition, both cytoplasmic and nuclear receptors sediment at 4 S in 0.4 M KCl and a major fraction of the nuclear receptor has an agarose elution profile identical to that of the cytoplasmic receptor. Thus a major fraction of the nuclear receptors is indistinguishable from the cytoplasmic receptors by the methods used. Since the cytoplasmic receptor sediments at 4 S in 0.15 M KCl, it is suggested that in vivo the glucocorticoid receptor may exist as a 4 S species and that the 7 S form described previously may result from an interaction of the 4 S component with other cytosol proteins in hypotonic media. About 25% of the receptor present in nuclear extracts has an agarose elution profile different from that of the cytoplasmic receptor in 0.4 M KCl. This suggests that either the nuclear receptor associates with itself or other nuclear proteins or that more than one form of nuclear receptor exists. Earlier observations suggested that in the absence of hormone the glucocorticoid receptor is localized exclusively in the cytoplasm of lung cells and that the nuclear receptor is formed by a transfer of the cytoplasmic steroid-receptor complex into the nucleus. A prerequisite for this transfer seems to be a modification of the receptor to an active form which can bind to nuclei. This receptor transfomration, referred to in this paper as activation of the receptor, can occur in the absence of nuclei and is highly dependent on temperature and ionic strength. Cytoplasmic receptors activated either by heating or by exposure to high ionic strength are indistinguishable from nonactivated receptors by sucrose density gradient analysis or by agarose gel filtration in solutions containing 0.4 M KCl. Simiarly, no significant difference in the absence of salt is observed after activation by heating. These results suggest that activation of the cytoplasmic glucocorticoid receptor involves conformational changes which favor its transfer and/or binding to nuclear sites rather than conversion of a 4 S species to a faster-sedimenting form by dimerization or by addition of another protein unit as has been proposed for the activation of the estrogen receptor of the rat uterus.     

Cardamine calliphaea sp. nov. (Brassicaceae) from southwestern Greece

Cardamine calliphaea Kit Tan, G. Vold & Giannopoulos sp. nov. (Brassicaceae) is illustrated and described as a new species endemic to Greece. It occurs in the prefectures of Ilia in western Peloponnese and Etolias‐Akarnanias in western Sterea Ellas and bears some resemblance to C. graeca, differing by its dense greyish–white indumentum and by the absence of leaf auricles. Affinities lie with C. glauca and C. plumieri from which it differs conspicuously, among other characters, by its imparipinnate leaves with the terminal leaflet smaller or equal in size to the lateral pairs.     

Control of stem cell fate by engineering their micro and nanoenvironment

Stem cells are capable of long-term self-renewal and differentiation into specialised cell types, making them an ideal candidate for a cell source for regenerative medicine. The control of stem cell fate has become a major area of interest in the field of regenerative medicine and therapeutic intervention. Conventional methods of chemically inducing stem cells into specific lineages is being challenged by the advances in biomaterial technology, with evidence highlighting that material properties are capable of driving stem cell fate. Materials are being designed to mimic the clues stem cells receive in their in vivo stem cell niche including topographical and chemical instructions. Nanotopographical clues that mimic the extracellular matrix(ECM) in vivo have shown to regulate stem cell differentiation. The delivery of ECM components on biomaterials in the form of short peptides sequences has also proved successful in directing stem cell lineage. Growth factors responsible for controlling stem cell fate in vivo have also been delivered via biomaterials to provide clues to determine stem cell differentiation. An alternative approach to guide stem cells fate is to provide genetic clues including delivering DNA plasmids and small interfering RNAs via scaffolds. This review, aims to provide an overview of the topographical, chemical and molecular clues that biomaterials can provide to guide stem cell fate. The promising features and challenges of such approaches will be highlighted, to provide directions for future advancements in this exciting area of stem cell translation for regenerative medicine.     

Multisensory stimulation can induce an illusion of larger belly size in immersive virtual reality

Background

Body change illusions have been of great interest in recent years for the understanding of how the brain represents the body. Appropriate multisensory stimulation can induce an illusion of ownership over a rubber or virtual arm, simple types of out-of-the-body experiences, and even ownership with respect to an alternate whole body. Here we use immersive virtual reality to investigate whether the illusion of a dramatic increase in belly size can be induced in males through (a) first person perspective position (b) synchronous visual-motor correlation between real and virtual arm movements, and (c) self-induced synchronous visual-tactile stimulation in the stomach area.

Methodology

Twenty two participants entered into a virtual reality (VR) delivered through a stereo head-tracked wide field-of-view head-mounted display. They saw from a first person perspective a virtual body substituting their own that had an inflated belly. For four minutes they repeatedly prodded their real belly with a rod that had a virtual counterpart that they saw in the VR. There was a synchronous condition where their prodding movements were synchronous with what they felt and saw and an asynchronous condition where this was not the case. The experiment was repeated twice for each participant in counter-balanced order. Responses were measured by questionnaire, and also a comparison of before and after self-estimates of belly size produced by direct visual manipulation of the virtual body seen from the first person perspective.

Conclusions

The results show that first person perspective of a virtual body that substitutes for the own body in virtual reality, together with synchronous multisensory stimulation can temporarily produce changes in body representation towards the larger belly size. This was demonstrated by (a) questionnaire results, (b) the difference between the self-estimated belly size, judged from a first person perspective, after and before the experimental manipulation, and (c) significant positive correlations between these two measures. We discuss this result in the general context of body ownership illusions, and suggest applications including treatment for body size distortion illnesses.