The usefulness of metaphase I oocytes in women who undergo controlled ovarian hyperstimulation for intracytoplasmic sperm injection.

OBJECTIVE: The aim of this study was to evaluate the fertilization and blastocyst formation rates of oocytes in metaphase I (MI) obtained from women who underwent controlled ovarian hyperstimulation (COH) for intracytoplasmic injection. METHODS: A prospective cohort study that included women from whom at least 1 MI and 1 MII oocyte were obtained after COH was performed. We collected 1,907 oocytes from 164 women (1291 MII, 352 MI and 258 prophase I or atretic). After oocyte classification, the MII and MI oocytes were incubated for 4 hours. RESULTS: After 4 hours, the rescue maturation rate was 57.2%; 205 MI oocytes matured to MII oocytes in vitro (rescued MI-MII group), and 153 remained in MI (arrested MI group). The normal fertilization rates were directly associated with oocyte maturation, with rates of 79.1%, 60.2%, and 31.9% in MII, MI-MII and MI oocytes, respectively (p<0.001). Group arrested MI had an odds ratio (OR) of 7.6 (CI 5.2 - 11.2, p<0.001) for abnormal fertilization compared with Group MII. The blastocyst formation rate was directly associated with oocyte maturation, at 36.4% for MII, 11.4% for MI-MII and 0.6% for MI. CONCLUSION: Oocytes collected at the MI stage after OCH that did not mature to MII after rescue maturation had a blastocyst formation rate of only 0.6%, while those in MII and MI-MII had rates of 36.4% and 11.4%, respectively. However, we found a pregnancy with the birth of a healthy baby from a blastocyst formed after intracytoplasmic sperm injection (ICSI) of an MI oocyte.

Synergism in the desorption of polycyclic aromatic hydrocarbons from soil models by mixed surfactant solutions.

This study investigates the effect of a mixed surfactant system on the desorption of polycyclic aromatic hydrocarbons (PAHs) from soil model systems. The interaction of a non-ionic surfactant, Tween 80, and an anionic one, sodium laurate, forming mixed micelles, produces several beneficial effects, including reduction of adsorption onto solid of the non-ionic surfactant, decrease in the precipitation of the fatty acid salt, and synergism to solubilize PAHs from solids compared with individual surfactants.

Different behaviours in the solubilization of polycyclic aromatic hydrocarbons in water induced by mixed surfactant solutions.

Water solubility of polycyclic aromatic hydrocarbons (PAHs), viz, naphthalene and phenanthrene, in micellar solutions at 25°C was investigated, using two series of different binary mixtures of anionic and nonionic surfactants. Tween 80 and Brij-35 were used as nonionic surfactants whereas fatty acids or amphiphilic cyclodextrins (Mod-ß-CD) synthesized in our laboratory were used as anionic ones. Solubilization capacity has been quantified in terms of the molar solubilization ratio and the micelle-water partition coefficient, using UV-visible spectrophotometry. Anionic surfactants exhibited less solubilization capacity than nonionics. The mixtures between Tween 80 and Mod-ß-CD did not show synergism to increase the solubilization of PAHs. On the other hand, the mixtures formed by Tween 80 and fatty acids at all mole fractions studied produced higher enhancements of the solubility of naphthalene than the individual surfactants. The critical micellar concentration of the mixtures of Tween 80/sodium laurate was determined by surface tension measurements and spectrofluorimetry using pyrene as probe. The system is characterized by a negative interaction parameter (ß) indicating attractive interactions between both surfactants in the range of the compositions studied.

Aggregation behavior of Brij-35/perfluorononanoic acid mixtures.

The mixed system of a nonionic hydrocarbon surfactant, polyoxyethylene (23) lauryl ether (Brij-35), and a perfluorinated surfactant, perfluorononanoic acid, was investigated by a combination of methods. The critical micelle concentrations (cmc's) have been determined over a wide range of sample compositions by fluorescence and UV-visible spectrophotometry using pyrene and N-(4-nitrophenyl) perfluorononanamide, respectively, as molecular probes. The values of the cmc's obtained were considerably different with the two techniques employed. Measurements of the (19)F nuclear magnetic resonance chemical shift of the same mixtures showed two breaks in the plots of Δδ(f) versus molar fraction of the perfluorinated surfactant. Conductivity and surface tension measurements also showed two breaks. The behavior is attributed to the formation of mixed micelles that change their composition when the fraction of the fluorinated compound increases and some segregation of the fluorinated compound takes place at a high total surfactant concentration.