PubMed Health⌕ Search

Biomedical subjects

L Aronow

Publications and source records attributed to L Aronow.

At least 19 recordsLinked to original sources
PubMed1988

Egg-oviduct interaction initiates reproductive behavior.

The experiments reported in this paper provide evidence that eggs must pass through the oviducts in order for receptivity to occur after ovulation in the female frog, Rana pipiens. In one experiment, oviductectomized frogs remained unreceptive after ovulation was induced by administration of exogenous pituitary glands, while sham-operates became receptive within 48 hr. Another experiment had four groups of subjects: ovariectomized females, females with oviducts ligated at the ostial end, females with openings in the uteri that prevented eggs from accumulating there, and sham-operated females. Only the last two groups, groups in which eggs could pass through the oviducts, became receptive. In these experiments, receptivity was indicated by absence of the release call during manual clasping of the trunk. Earlier experiments have shown that eggs have to pass through the oviducts in order to become fertilizable. Thus, the passage of eggs through the oviducts provides a mechanism which links the onset of reproductive behavior to the availability of fertilizable gametes.

Animals↗
PubMed1980

The narrow gauge.

Explore the source record for details and available documents.

Educational Measurement↗
PubMed1979

Effects of glucocorticoids on fibroblasts.

Mouse fibroblasts growing in vitro respond to glucocorticoids in a dose-dependent fashion by reduced rates of growth. The inhibition of growth observed in vitro is related to the topical anti-inflammatory action of glucocorticoids and to their capacity to inhibit wound repair. The cells growing in vitro possess a glucocorticoid receptor system that has been studied in some detail using [3H]triamcinolone acetonide as a radiolabeled ligand. The initial binding reaction occurs in the cytosol. The complex is then rapidly taken up in the nucleus of the cell by a temperature-sensitive process. In the nucleus, the complex exists in two forms, one of which is readily extracted by 0.3 M KCl solutions. A small amount of steroid-receptor complex is tightly bound to chromatin. Under normal incubation conditions, there is a constant cycling of steroid-receptor complex, and unbound receptor is generated back into the cytosol from the nucleus with a half-life of about 30 min. Regeneration of unbound receptor does not depend on protein synthesis and is a temperature-sensitive and energy-requiring process. Incubating the steroid-treated cells in the absence of glucose and in the presence of inhibitors such as cyanide or dinitrophenol leads to a loss of cytoplasmic steroid-receptor complexes, and an accumulation of the complex in the nuclear residual form, tightly bound to chromatin. With respect to nuclear effects of steroid treatment, we have found that incubating fibroblasts in vitro with glucocorticoids produces a prompt decrease in the amount of a satellite H1 histone found in these cells.

Animals↗
PubMed1977

Physicochemical properties of glucocorticoid receptors from mouse fibroblasts.

Glucocorticoid-bound receptor macromolecules were prepared in three forms from mouse fibroblast cells: the cytosol receptor, the nuclear extractable receptor, and the nuclear residual form obtained by DNase digestion of chromatin samples. These receptor complexes were studied with respect to gel filtration properties, sedimentation velocities in various salt concentrations, partial specific volumes, isoelectric points, and thermal stability properties. The results indicate that the three forms of the receptor differ in their molecular properties, and nuclear translocation and binding ofthe receptor complex is associated with conformational and physical changes consistent with a reduction in apparent molecular weight.

Cell Fractionation↗
PubMed1977

Glucocorticoid receptors and inhibition of bone cell growth in primary culture.

We have previously identified glucocorticoid binding proteins in cytosol of cells dispersed from fetal rat calvaria by collagenase digestion. The present study, employing primary culture of these cells, provides further evidence that these binding proteins represent glucocorticoid receptors. [3H]Dexamethasone bound to cytoplasmic extracts of cultured cells with an apparent Kdiss of 6.8 nM and exhibited approximately 8500 binding sites/cell. Nuclear translocation of [3H]dexamethasone was demonstrated with approximately 50% of bound steroid extractable from the nuclear pellet after incubation at 37 C; little nuclear transfer occurred at 0 C. The specificity of these binding site was characterized by competition studies with other steroids in whole cells, the order of affinities being: triamcinolone acetonide greater than dexamethasone greater than progesterone greater than cortisol greater than corticosterone = cortexolone. Non-glucocorticoids except progesterone competed only poorly. Sedimentation analysis of [3H]dexamethasone-protein complexes on sucrose gradients revealed a cytoplasmic peak of 6.5 S in salt-free gradients and 3.8 S in 0.3 M KCl gradients. Dexamethasone addition to the culture medium resulted in a dose-dependent inhibition of cell growth with approximately 40% reduction in cell number at 13 nM. That this inhibition was receptor mediated was substantiated by the partial blockade of the dexamethasone effect in the presence 1.3 microM progesterone. Functionally, dexamethasone inhibits the growth of these cells. These data provide evidence for receptor mediated inhibitory effects of glucocorticoids directly at the level of the bone cell.

Animals↗
PubMed1975

Subcellular distribution of glucocorticoid receptors in mouse fibroblasts.

Mouse fibroblasts contain a macromolecular binding component (receptor) which binds glucocorticoids specifically and with high affinity. This study shows that there are three different cellular forms of bound receptor and that it is experimentally possible to markedly alter the subcellular distribution of these three forms. Cells incubated with (3H)triamcinolone acetonide were broken after hypotonic shock and a 7000g hypotonic supernatant was obtained; the pellet was extracted with 0.3 M KCl, yielding a nuclear extract; the remaining pellet was resuspended in water, sonicated, and assayed for "nuclear residual" (i.e., nonextractable) radioactivity. If whole cells are incubated at 0 degrees in a growth medium, almost all of the bound steroid is located in the hypotonic supernatant fraction. Incubation at 37 degrees produces a shift of the steroid-bound macromolecule into the nuclear extractable form, while omission of glucose and addition of KCN at 37 degrees markedly increase the nuclear residual form at the expense of both the nuclear-extractable and supernatant forms. Since DNase treatment of chromatin liberates a soluble steroid-receptor complex, we believe that the nuclear residual form may be steroid-receptor complex tightly bound to chromatin. We propose a model suggesting that an energy-requiring process is required to generate free receptor from the chromatin complex to complete the normal cellular recycling system.

Animals↗