Mechanism of action of levonorgestrel: in vitro metabolism and specific interactions with steroid receptors in target organs.

Levonorgestrel (LNG) is a synthetic steroid that displays potent progestional and androgenic effects but it lacks estrogen-like activity. To examine the mode of action of this progestin, we studied its metabolism in vitro in target organs and the specific interactions of LNG and its metabolites with putative steroid receptors. The results demonstrated that [³H]LNG was efficiently converted to A-ring reduced derivatives when incubated with rat hypothalamus and pituitary. Under optimal incubation conditions, [³H]5-dihydro LNG (5-LNG) and [³H]3-5-tetrahydro LNG (3,5-LNG) were identified as the major metabolic conversion products, while [³H]3ß, 5-LNG formation occured to a lesser extent. A-ring reduction of LNG was NADPH-dependent. Assessment of the relative binding affinities of LNG and its derivatives to progesterone (PR), androgen (AR) and estrogen (ER) receptors by displacement analysis revealed that unchanged LNG binds with high affinity to PR and AR but not to ER. 5-LNG exhibited a diminished though significant interactions with PR and an enhanced binding affinity for AR as compared with LNG, indicating that 5-reduction of LNG increases its affinity for AR. The most striking finding was that further reduction of the 5-LNG molecule at C-3 abolished its binding activity to PR, AR, and even to ER. The overall data provides a plausible explanation for the lack of estrogen agonistic action of LNG and for its potent progestational and androgenic effects.     

In vitro antimicrobial effect of metallic nanoparticles on phytopathogenic strains of crop plants

In this research, the in vitro antimicrobial effect of zinc oxide (ZnO), copper oxide (CuO) and iron oxide (Fe₂O₃) nanoparticles (NPs)—with average sizes of 20, 46 and 30 nm, respectively—on the root rot disease caused by the fungus Fusarium oxysporum and on blight disease caused by the fungus Alternaria solani were studied. Also, bacterial diseases caused by Clavibacter michiganensis and Pseudomonas syringae that infects a wide range of plant species were assessed. Different concentrations of NPs (0, 100, 250, 500, 700 and 1,000 mg/L) were prepared on PDA agar or King's B medium in a complete randomized design with four replicates. According to the results, ZnO NPs exhibited an outstanding inhibitory effect against fungi and bacteria strains. The above results were associated with the smaller particle size. Fungi strains showed a differential sensitivity depending on the kind of NPs used. A. solani showed the highest sensitivity to ZnO NPs at 1,000 mg/L (99%), followed by CuO NPs at the same dose (95%). Fe₂O₃ NPs at all evaluated doses had no inhibitory effects on the mycelia growth of this strain, although F. oxysporum revealed greater effectiveness of the CuO NPs (96%) compared with ZnO NPs since it only inhibited 91% of the mycelial growth. The antibacterial activity was studied through optical density. C. michiganensis was found to be more sensitive to ZnO NPs because a lesser dose (700 mg/L) was required to reduce the bacterial growth (90%); in comparison, P. syringae required a dose of 1,000 mg/L to inhibit its growth (67%). CuO NPs displayed the smallest growth inhibition against the bacteria strains analysed. The antimicrobial effect of the metallic NPs that were assayed increased with higher doses.     

Ethanol effect on the chick embryo ossification: a macroscopic and microscopic study

This study attempts to analyze anomalies in avian embryos induced macroscopically and microscopically when exposed to ethanol (EtOH) during the first stages of development. Fertilized chicken eggs were employed in this study. The eggs were incubated at 37.8 degrees C. Some of the eggs were treated on day 0 with EtOH (20%, 40% and 60%) by instillation in the air sac. The control group was instilled with 0.1 ml of NaCl at 0.9%. Other eggs were treated on the 4th post-incubation day, employing the same methodology. The embryos in both groups were removed from the eggs on the 11th incubation day and examined using a dissecting binocular microscope. After macroscopic analysis, the samples obtained were fixed in 10% formol, photographed and processed according to common histological techniques and the Picrosirius method. Embryos treated with EtOH demonstrated a significant weight decrease. Microscopic analysis by means of the Picrosirius method revealed that the intra-membranous ossification process presents less development, and therefore there was less type I collagen in trabecular bone in the embryos post-exposure to EtOH with respect to the control.     

Microscopic and histochemical study of odontoclasts in physiologic resorption of teeth of the polyphyodont lizard, Liolaemus gravenhorsti

Using tartrate-resistant acid phosphatase (TRAP), we examined the cytodifferentiation of odontoclast cells in resorbing areas of dental tissues during the replacement of teeth in a polyphyodont lizard, Liolaemus gravenhorsti. We also report, by means of Lectin-HRP histochemistry, the distribution pattern of some specific sugar residues of TRAPase-positive cells. For detection of TRAPase activity, the azo dye-coupling technique was used. Lectin binding sites were demonstrated by means of specific HRP-lectins. The process of tooth resorption was divided into four stages: 1) preresorption-the wall of the dental pulp is covered with an odontoblast layer, and no TRAP-positive cells are in the dental pulp; 2) early resorption-TRAP-positive multinucleate odontoclasts are present on the dental wall, but the rest of the pulp surface is still covered with an odontoblast layer; 3) later resorption-the entire surface of the pulp chamber is lined with multinucleate odontoclasts; and 4) final resorption-the tooth has been totally resorbed. Odontoclasts are usually detached from the resorbed surface, and show signs of degeneration. Of the six lectins used, PNA, ECA, and UEA-1 bind to multinucleated but not mononuclear cells. All the remaining lectins, BS-1, RCA(120), and LTA showed no binding to any cells of the teeth. The significance of saccharidic moieties such as acetyl-galactosamine, acetyl-glucosamine, and fucose sugar residues is difficult to ascertain. Perhaps these oligosaccharides might be borne on molecules associated with odontoclastic resorption or associated with multinucleation of odontoclasts after attachment to the dentine surface.     

Effects of betamethasone,sulindac and quinacrine drugs on the inflammatory neoangiogenesis response induced by polyurethane sponge implanted in mouse

In this study, we showed the effect of the betamethasone, sulindac and quinacrine alone or combined, on the inflammatory angiogenesis promoted by polyurethane sponge on mice. The main finding reported here is that the formation of new blood vessels was strongly inhibited by low concentration of betamethasone, sulindac or quinacrine, whether alone or in combination. It is known that steroidal anti-inflammatory drugs inhibit the enzymes required for the production of prostaglandins through a nuclear glucocorticoid receptor (GR) mediated mechanism. This mechanism may occur in endothelial cells as well. Considering that activity of cyclo-oxigenases 1 and 2 is inhibited by sulindac, and that these enzymes are located in the stromal tissue, we propose that the anti-angiogenic effect of these agents may occur via inhibition of both COX isoforms. On the other hand, quinacrine inhibited PLA2 activity, and we propose here that the anti-angiogenic effect occurs via inhibition of the enzyme PLA2. The potentiated effect of the association of betamethasone, sulindac and quinacrine may have some therapeutic benefit in the control of pathological angiogenesis. Further studies are required to validate these propositions.     

Novel lopinavir analogues incorporating non-Aromatic P-1 side chains--synthesis and structure--activity relationships

The HIV protease inhibitor Lopinavir has a pseudosymmetric core unit incorporating benzyl groups at both P-1, P-1' positions. A series of analogues incorporating non-aromatic side chains at the P-1 position were synthesized and the structure-activity relationships explored.     

RNA/DNA ratio as an index of physiological condition of Colossoma macropomum and Piaractus branchypomus (Pisces: Characiformes) during embryonic development

We evaluated RNA/DNA ratio as an index of physiological condition during larval development of a hybrid between the fishes Colossoma macropomum (cachama) and Piaractus brachypomus (morocoto). The samples were obtained by induced reproductive technology and the eggs were maintained in acrylic conical incubator with a continuous waterflow. Embryonic development, from egg fertilization to cell division and hatch out, took 12 hours 20 minutes at 29.5 degrees C, dissolved oxygen contents of 6.0 ppm and pH 7.5. Nucleic acids quantification was determined by fluorometry with ethidium bromide and Hoechst 33258 dyes. We observed significant changes of RNA/DNA ratios during all stages of the embryonic larval development. Therefore, RNA/DNA relation is an useful technique to evaluate physiological condition in short period and could be utilized as nutritional condition and/or instantaneous growth for routine check to verify the health status in early life of cultivated species.     

Determination of prednisolone and the most important associated compounds in ocular and cutaneous pharmaceutical preparations by micellar electrokinetic capillary chromatography

A micellar electrokinetic capillary chromatographic method to separate prednisolone, prednisolone acetate, naphazoline, Zn-bacitracin, sulfacetamide and phenylefrine is described. The separation was carried out by using a fused-silica capillary (57 cmx75 micrometer I.D.) at 25 degrees C and 30 kV, using a 5 mM phosphate-5 mM borate buffer adjusted to pH 8.2, 50 mM sodium dodecyl sulfate (SDS) and 10% methanol-water (v/v) as background electrolyte. Under these conditions, the run time was 8 min and the limits of quantification were about 1.0 mg/l for every component. The method was applied to pharmaceutical preparations and the results provided recoveries close to 100% and the method gave good results when compared with a reference multivariate calibration spectrophotometric method.     

Cooper, cadmium and lead in the fish Cyprinodon dearborni, in the sediments and in the water of two lagoons in Venezuela

The concentration of copper, cadmium and lead in superficial sediment, water and the fish Cyprinodon dearborni was determined in two coastal lagoons of Sucre State, Venezuela. Chacopata lagoon is hyper saline while Los Patos lagoon is hypo saline and receives significant wastewater from Cumaná city. Water, sediment and fish samples were collected in February 1998. In the laboratory, samples underwent acid digestion and were analyzed by atomic absorption spectophotometry. The mean values of the metals in C. dearborni from the Chacopata lagoon were: 159.26 +/- 210.68 microg/g for Cu, 44.71 +/- 45.58 microg/g for Cd, and 9.31 +/- 23.34 microg/g for Pb, while for Los Patos lagoon the mean values were: 64.88 +/- 16.30, 19.48 +/- 5.81 and 22.85 +/- 20.00, respectively. In the water column, the metal concentration ranges were: 2.3-11.6, 3.9-5.4 and 21-32 mg/l for copper, cadmium and lead, respectively. These results suggest that metal levels in sediment, water column and organisms in both lagoons do not differ, except for lead, even though only Los Patos receives waste water.