Factors determining the kinetics of a single dose of testosterone in rats

The results from different authors regarding testosterone and cognitive research show controversial results. One of the reasons may be the form of testosterone used in the experiment. The aim of our study was to evaluate the testosterone levels in plasma and its kinetics after the single application of either a long-acting or a short-acting form of this hormone. Twenty female and twenty male adult Wistar rats were divided into two groups that were either gonadectomized or not. The two groups were divided into 4 subgroups depending on whether the animals received testosterone propionate or testosterone isobutyrate intramuscularly. Samples for analysis were collected before and at 2, 4, 24, 48, 72, 96 and 168 h after injection. The results showed significant differences in the dynamics between rapid and depot forms of testosterone, together with the rebound effect and hormonal negative feedback. These aspects of testosterone kinetics need to be considered when planning experiments on the physiology of testosterone

Correction: Enhanced Mitogenic Activity of Recombinant Human Vascular Endothelial Growth Factor VEGF121 Expressed in E. coli Origami B (DE3) with Molecular Chaperones.

[This corrects the article DOI: 10.1371/journal.pone.0163697.]

Enhanced Mitogenic Activity of Recombinant Human Vascular Endothelial Growth Factor VEGF₁₂₁ Expressed in <i>E</i>. <i>coli</i> Origami B (DE3) with Molecular Chaperones

<div><p>We describe the production of a highly-active mutant VEGF variant, α₂-PI_1-8-VEGF₁₂₁, which contains a substrate sequence for factor XIIIa at the aminoterminus designed for incorporation into a fibrin gel. The α₂-PI_1-8-VEGF₁₂₁ gene was synthesized, cloned into a pET-32a(+) vector and expressed in <i>Escherichia coli</i> Origami B (DE3) host cells. To increase the protein folding and the solubility, the resulting thioredoxin-α₂-PI_1-8-VEGF₁₂₁ fusion protein was co-expressed with recombinant molecular chaperones GroES/EL encoded by independent plasmid pGro7.</p><p>The fusion protein was purified from the soluble fraction of cytoplasmic proteins using affinity chromatography. After cleavage of the thioredoxin fusion part with thrombin, the target protein was purified by a second round of affinity chromatography. The yield of purified α₂-PI_1-8-VEGF₁₂₁ was 1.4 mg per liter of the cell culture. The α₂-PI_1-8-VEGF₁₂₁ expressed in this work increased the proliferation of endothelial cells 3.9–8.7 times in comparison with commercially-available recombinant VEGF₁₂₁. This very high mitogenic activity may be caused by co-expression of the growth factor with molecular chaperones not previously used in VEGF production. At the same time, α₂-PI_1-8-VEGF₁₂₁ did not elicit considerable inflammatory activation of human endothelial HUVEC cells and human monocyte-like THP-1 cells.</p></div