17ß-estradiol replacement therapy induces eNOS, nNOS and estrogen receptor ß in hypophysectomized rats with inflamed footpads.

Nitric oxide (NO) plays a key role in inflammation. It is partly produced by three forms of NOS: eNOS of inflammatory cells, nNOS of neural cells and iNOS (inducible isoform). Estrogens can cause an anti-inflammatory effect, although it is not yet clear through which NOS isoforms. The aim of this study was to evaluate the role of the different NOS isoforms, as well as estrogen receptors (ERs) α and ß, on the anti-inflammatory effects of estrogens. To avoid the influence of endogenous glucocorticoids or sexual hormones, male rats were hypophysectomized. Animals were segregated into two control groups (no-treatment control group and SHAM-operated animals) and three hypophysectomized groups (no-hormonal treatment, with estradiol-17ß, or with testosterone replacement treatment). Freund's complete adjuvant (1 mg) was administered to the footpad of all animals. Measurements were made based on footpad inflammation (with a plethysmometer) such as eNOS, nNOS, iNOS and ER α and ß protein expression (by immunohistochemistry principle/method) on days 1, 7 and 14. Only estradiol decreased inflammation, accompanied by increased levels of eNOS and nNOS and differential expression of ERs α and ß in the inflammatory infiltrate. The higher levels of estradiol-induced eNOS and nNOS ocurred perhaps through the activation of ER ß.

Computational Study of the Binding Modes of Diverse DPN Analogues on Estrogen Receptors (ER) and the Biological Evaluation of a New Potential Antiestrogenic Ligand.

Estrogen (17ß-estradiol) is essential for normal growth and differentiation in the mammary gland. In the last three decades, previous investigations have revealed that Estrogen Receptor Alpha (ERα) plays a critical role in breast cancer. More recently, observations regarding the widespread expression of ERß-like proteins in normal and neoplastic mammary tissues have suggested that ERß is also involved in the mentioned pathology. Design of new drugs both steroidal and nonsteroidal that target any of these receptors represents a promise to treat breast cancer although it remains a challenge due to the sequence similarity between their catalytic domains. In this work, we propose a new set of compounds that could effectively target the estrogen receptors ERα and ERß. These ligands were designed based on the chemical structure of the ERß-selective agonist Diarylpropionitrile (DPN). The designed ligands were submitted to in silico ADMET studies, yielding in a filtered list of ligands that showed better drug-like properties. Molecular dynamics simulations of both estrogen receptors and docking analysis were carried-out employing the designed compounds, from which two were chosen due to their promising characteristics retrieved from theoretical results (docking analysis or targeting receptor predictions). They were chemically synthetized and during the process, two precursor ligands were also obtained. These four ligands were subjected to biological studies from which it could be detected that compound mol60b dislplayed inhibitory activity and its ability to activate the transcription via an estrogenic mechanism of action was also determined. Interestinly, this observation can be related to theoretical binding free energy calculations, where the complex: ERß-mol60b showed the highest energy ΔGbind value in comparison to others.

Purification and cellular localization of the Entamoeba histolytica transcarboxylase.

Genome analysis of Entamoeba histolytica predicts the presence of acetyl-CoA carboxylase. Using Western blot, histochemistry, and confocal microscopy, we demonstrated the presence of a biotin-containing protein in the cytoplasm of E. histolytica, with a molecular weight of 136 kDa and biotin-carboxylase activity. This protein probably corresponds to a transcarboxylase that catalyzes the rate-limiting reaction leading to fatty acid elongation.

Hypophysectomy and neurointermediate pituitary lobectomy decrease humoral immune responses to T-independent and T-dependent antigens.

In rats, hypophysectomy (HYPOX) or neurointermediate pituitary lobectomy (NIL) reduce humoral and cell-mediated immune responses. However, to our knowledge, the differences in the effects of anterior versus posterior pituitary hormones on the immune responses have not been studied to date. We compared in rats, the effects of sham surgery (SHAM), HYPOX, and NIL on humoral immune responses to T cell-independent (TI) type 1 antigen DNP-LPS and to TI type 2 antigen DNP-FICOLL, as well as to T cell-dependent (TD) antigens ovalbumin (OVA) and bovine serum albumin (BSA). The results showed that: (1) both HYPOX and NIL induced a similar and significant decrease in IgM responses towards TI-1 antigens, (2) NIL but not HYPOX induced a decreased IgM response to TI-2 antigens, and (3) both HYPOX and NIL induced similar and significant decrease in IgG responses to TI-2 antigens. Compared with the SHAM group, IgM responses to both TD antigens did not change in HYPOX and NIL animals, whereas the IgG responses to OVA and BSA significantly decreased in HYPOX and NIL animals. These results indicate that hormones of the anterior and posterior pituitary play their own role in the regulation of humoral immune responses.

Mycobacterium tuberculosis virulence correlates with mitochondrial cytochrome c release in infected macrophages.

Mitochondria are at the centre of molecular events involved in energy production, cell survival and apoptosis. Mitochondrial membrane potential (Deltapsim) is maintained by cellular catabolic reactions and the electron transport chain of which cytochrome c is a constituent, whereas the proton leak pathway, ATP synthesis and turnover consume it. Mitochondrial alterations such as a drop in Deltapsim, swelling and cytochrome c release have been observed in apoptosis. However, there is a paucity of information concerning mitochondrial function in the course of intracellular infections, a process that must certainly induce stress on the host cell. This work analyses the effect that two strains of mycobacteria of opposing virulence have on the mitochondria of murine macrophages in the early stages of infection. It was found that infection of J774 cells with both Mycobacterium tuberculosis H37Ra and M. tuberculosis H37Rv readily induced changes in Deltapsim as well as in mitochondrial morphology at the ultrastructural level. In addition, an increase in cytosolic ATP was found at 24 h post infection with both strains of M. tuberculosis. Interestingly, only M. tuberculosis H37Rv was able to induce cytochrome c release from mitochondria to the cytosol, thus suggesting the occurrence in M. tuberculosis H37Rv of a specific factor(s) capable of regulating cytochrome c translocation. The precise role of cytochrome c release in the context of a mycobacterial infection remains to be elucidated.