A role for the androgen receptor in the endometrial antiproliferative effects of progesterone antagonists

In women and nonhuman primates, treatment with progesterone antagonists suppresses estrogen-dependent mitotic activity in the endometrial glands. This antiproliferative effect is paradoxical, because progesterone antagonists do not bind to the estrogen receptor (ER). While this phenomenon has been termed a "functional noncompetitive antiestrogenic effect," it does not occur in all species or in all regions of the primate reproductive tract, so is best referred to as an "endometrial antiproliferative effect." Recent studies of ours in both women and macaques revealed that the endometrial androgen receptor (AR) was increased by progesterone antagonist treatment. Because androgens are known to suppress estrogen-dependent endometrial proliferation, we hypothesized that the AR was involved in the antiproliferative effects induced by progesterone antagonists. In a test of this hypothesis, we administered the antiandrogen, flutamide, along with progesterone antagonists to ovariectomized, estrogen-treated macaques. Flutamide counteracted the suppressive effects of the progesterone antagonists on endometrial wet weight, thickness, stromal compaction, and mitotic index. Hyaline degeneration of the spiral arteries was also blocked by flutamide. These data implicate the AR as a functional component of the mechanism through which progesterone antagonists induce endometrial antiproliferative effects in the presence of estrogens.     

Antiprogestins as a model for progesterone withdrawal

The key physiological function of the endometrium is preparation for implantation; and in the absence of pregnancy, menstruation and repair. The withdrawal of progesterone is the initiating factor for breakdown of the endometrium. The modulation of sex steroid expression and function with pharmacological agents has provided an invaluable tool for studying the functional responses of the endometrium to sex steroids and their withdrawal. By administration of the antiprogestin mifepristone, it is possible to mimic progesterone withdrawal and study local events in early pregnancy decidua that may play a role in the process of early pregnancy failure. Our data indicate that antagonism of progesterone action at the receptor level results in an up-regulation of key local inflammatory mediators, including NF-kappaB, interleukin-8 (IL-8), monocyte chemotactic peptide-1 (MCP-1), cyclooxygenase 2 (COX-2) and others in decidua. Bleeding induced by mifepristone in the mid-luteal phase of the cycle is associated with changes in the endometrium similar to those that precede spontaneous menstruation including up-regulation of COX-2 and down-regulation of PGDH. Administration of antagonists of progesterone provide an excellent model to study the mechanisms involved in spontaneous and induced abortion as well as providing information which may help devise strategies for treating breakthrough bleeding associated with hormonal contraception.     

Issues and strategies in the DNA identification of World Trade Center victims

Identification of the nearly 3000 victims of the World Trade Center attack, represented by about 15,000 body parts, rests heavily on DNA. Reference DNA profiles are often from relatives rather than from the deceased themselves. With so large a set of victims, coincidental similarities between non-relatives abound. Therefore considerable care is necessary to succeed in correlating references with correct victims while avoiding spurious assignments. Typically multiple relatives are necessary to establish the identity of a victim. We describe a 3-stage paradigm--collapse, screen, test--to organize the work of sorting out the identities. Inter alia we present a simple and general formula for the likelihood ratio governing practically any potential relationship between two DNA profiles.     

Fast corrections of movements with a computer mouse

When we reach out for an object with our hand, we transform visual information about the object's position into muscle contractions that will bring our digits to that position. If we reach out with a tool the transformation is different, because the muscle contractions must bring the critical part of the tool to the object, rather than the digits. The difference between the motion of the hand and that of the tool can be quite large, as when moving a computer mouse across a table to bring a cursor to a position on a screen. We examined the responses to unpredictable visual perturbations during such movements. People responded about as quickly to changes in the position of the target when pointing with the mouse as when doing so with their hand. They also responded about as quickly when the cursor was displaced as when the target was displaced. We show that this is not because the visually perceived separation between target and cursor is transformed into a desired displacement of the hand. Our conclusion is that our actions are controlled by the judged positions of the end-effector and the target, even when the former is quite detached from the muscles and joints that are involved in the action.     

Hormonal modulation of delta6 and delta5 desaturases: case of diabetes

Animal biosynthesis of high polyunsaturated fatty acids from linoleic, alpha-linolenic and oleic acids is mainly modulated by the delta6 and delta5 desaturases through dietary and hormonal stimulated mechanisms. From hormones, only insulin activates both enzymes. In experimental diabetes mellitus type-1, the depressed delta6 desaturase is restored by insulin stimulation of the gene expression of its mRNA. However, cAMP or cycloheximide injection prevents this effect. The depression of delta6 and delta5 desaturases in diabetes is rapidly correlated by lower contents of arachidonic acid and higher contents of linoleic in almost all the tissues except brain. However, docosahexaenoic n-3 acid enhancement, mainly in liver phospholipids, is not explained yet. In experimental non-insulin dependent diabetes, the effect upon the delta6 and delta5 desaturases is not clear. From all other hormones glucagon, adrenaline, glucocorticoids, mineralocorticoids, oestriol, oestradiol, testosterone and ACTH depress both desaturases, and a few hormones: progesterone, cortexolone and pregnanediol are inactive.     

Fhit-nucleotide specificity probed with novel fluorescent and fluorogenic substrates

Fhit, a member of the histidine triad superfamily of nucleotide-binding proteins, binds and cleaves diadenosine polyphosphates and functions as a tumor suppressor in human epithelial cancers. Function of Fhit in tumor suppression does not require diadenosine polyphosphate cleavage but correlates with the ability to form substrate complexes. As diadenosine polyphosphates are at lower cellular concentrations than mononucleotides, we sought to quantify interactions between Fhit and competitive inhibitors with the use of diadenosine polyphosphate analogs containing fluorophores in place of one nucleoside. Appp-S-(7-diethylamino-4-methyl-3-(4-succinimidylphenyl)) coumarin (ApppAMC), Appp-S-(4-4-difluoro-5,7-dimethyl-4-bora-3a, 4a-diaza-s-indacine-3-yl) methylaminoacetyl (ApppBODIPY), and GpppBODIPY, synthesized in high yield, are effective Fhit substrates, producing AMP or GMP plus fluorophore diphosphates. GpppBODIPY cleavage is accompanied by a 5.4-fold increase in fluorescence because BODIPY fluorescence is quenched by stacking with guanine. Titration of unlabeled diadenosine polyphosphates, inorganic pyrophosphate, mononucleotides, and inorganic phosphate into fluorescent assays provided values of K(m) and K(I) as competitive inhibitors. The data indicate that Fhit discriminates between good substrates via k(cat) and against cellular competitors in equilibrium binding terms. Surprisingly, pyrophosphate competes better than purine mononucleotides.     

The 5' stem-loop regulates expression of collagen alpha1(I) mRNA in mouse fibroblasts cultured in a three-dimensional matrix

The stability of collagen α1(I) mRNA is regulated by its 5′ stem–loop, which binds a cytoplasmic protein in a cap-dependent manner, and its 3′-untranslated region (UTR), which binds αCP. When cultured in a three-dimensional gel composed of type I collagen, mouse fibroblasts had decreased collagen α1(I) mRNA steady-state levels, which resulted from a decreased mRNA half-life. In cells cultured in gel, hybrid mouse–human collagen α1(I) mRNA with a wild-type 5′ stem–loop decayed faster than the same mRNA with a mutated stem–loop. When the 5′ stem–loop was placed in a heterologous mRNA, the mRNA accumulated to a lower level in cells grown in gel than in cells grown on plastic. This suggests that the 5′ stem–loop down-regulates collagen α1(I) mRNA. Protein binding to the 5′ stem–loop was reduced in cells grown in gel, which was associated with destabilization of the collagen α1(I) mRNA. In addition to the binding of a cytoplasmic protein, there was also a nuclear binding activity directed to the collagen α1(I) 5′ stem–loop. The nuclear binding was increased in cells grown in gel, suggesting that it may negatively regulate expression of collagen α1(I) mRNA. Binding of αCP, a protein involved in stabilization of collagen α1(I) mRNA, was unchanged by the culture conditions.