Monitoring single-cell bioenergetics via the coarsening of emulsion droplets.

Microorganisms are widely used to generate valuable products, and their efficiency is a major industrial focus. Bioreactors are typically composed of billions of cells, and available measurements only reflect the overall performance of the population. However, cells do not equally contribute, and process optimization would therefore benefit from monitoring this intrapopulation diversity. Such monitoring has so far remained difficult because of the inability to probe concentration changes at the single-cell level. Here, we unlock this limitation by taking advantage of the osmotically driven water flux between a droplet containing a living cell toward surrounding empty droplets, within a concentrated inverse emulsion. With proper formulation, excreted products are far more soluble within the continuous hydrophobic phase compared to initial nutrients (carbohydrates and salts). Fast diffusion of products induces an osmotic mismatch, which further relaxes due to slower diffusion of water through hydrophobic interfaces. By measuring droplet volume variations, we can deduce the metabolic activity down to isolated single cells. As a proof of concept, we present the first direct measurement of the maintenance energy of individual yeast cells. This method does not require any added probes and can in principle apply to any osmotically sensitive bioactivity, opening new routes for screening, and sorting large libraries of microorganisms and biomolecules.

The mean of sperm parameters in semen donations from the same donor. An important prognostic factor in insemination.

We analysed 12,100 consecutive cycles of artificial insemination by donor spermatozoa in 1901 infertile couples. In our analysis, particular attention was given to finding an appropriate way of taking into account the respective effects of female and male factors on the pregnancy success rate and the level at which these factors act (cycle vs. woman and donation vs. donor). A total of 1213 pregnancies occurred. The pregnancy rate per cycle was lower as the age of the woman increased (p < 0.0001) and varied with the type of infertility: fecundity was higher (p = 0.03) in the case of azoospermia than of severe oligozoospermia. After taking into account these factors, significant unexplained variation in likelihood to conceive remained. A part of this heterogeneity was shown to be due to variation in fecundability between semen donors. In order to explain this heterogeneity between donors, compositional covariates were used, particularly the mean of results of the semen analysis performed for donations from the same donor. For each semen characteristic, the overall mean of the different donations of a donor was an important predictive factor of successful insemination: after taking into account all of the other factors, the odds ratios for an increase of 50 x 10(6)/mL spermatozoa, of a 20% increase in sperm motility and of a 2 point increase in the post-thaw quality index, were, respectively, 1.13, 1.37 and 1.56. After adjustment for these factors, the specific characteristics of each semen donation were no longer significantly predictive of successful insemination. This observation has a biological interpretation: sperm with low parameters but produced by a normally fertile man can have a satisfactory success rate.

Seminal alpha-glucosidase activity as a marker of epididymal pathology in nonazoospermic men consulting for infertility.

Glucosidase (alpha G) activity was measured in sperm free seminal plasma from 1200 patients consulting for primary infertility, in whom clinical examination of epididymides revealed some abnormalities and histories of genital infections. They constituted the group with epididymal pathology (P) that was compared with a reference group (R) of 246 men without any epididymal pathology. The distribution of alpha G was significantly different between the two groups, even if we considered only the subjects in group P with normal sperm count (PN: 353 men: p less than 10(-6). 15.9% of subjects in group PN exhibited alpha G values as low as vasectomized men, versus 1.2% in group R. A linear relationship was established between alpha G and sperm content in both groups, but alpha G activities were systematically lower in group P (y = 0.19 x + 64) than in group R (y = 0.30 x + 86). There was no correlation between alpha G and the percent of sperm motility. On the contrary, we found statistically more clinical epididymal abnormalities in cases of decreased alpha G activity than in cases of normal alpha G activity (p less than .01).

[Significance of HCG injection for ovulation induction and of ovulation prediction factors in the practice of artificial insemination using donor sperm. A randomized study]. / Intérêt pour la pratique de l'insémination artificielle avec sperme de donneur de l'injection d'HCG déclenchant et des facteurs de prédiction de l'ovulation. Etude randomisée.

This randomised study was carried out on 77 patients who underwent 269 cycles of donor insemination (AID). The randomization was carried out to decide whether HCG should be used or not to provoke ovulation. The results in AID show, in our study, that using HCG in estimating oestradiol makes very little difference. On the other hand, measuring LH and the quality of the sperm that is used for the insemination seem to us to be important, whereas the quality of the cervical mucus is absolutely fundamental. Ultrasound makes it possible to determine the date when the AID should be carried out in difficult cases. The use of HCG to release the oocytes can be discussed when the cervical score is less than 7 when the other parameters are favourable, and in particular when the diameter of the dominant follicle is 18 mm or more. A higher pregnancy rate should be able to be obtained in AID if all parameters are looked at.

[Disturbances in ovulation following on artificial insemination with donors (A.I.D.) (author's transl)]. / Perturbations de l'ovulation consécutives à l'insémination artificielle avec donneurs (I.A.D.).

The authors report on the results of statistical analysis of temperature curves in 139 patients before artificial insemination from donors (A.I.D.) and in the cycles in which they were inseminated. It appears that frequently the practice of A.I.D. causes ovulation to come early or late. Late ovulation seems to be the most frequent cause of failures which are then considered to be due to "psychogenic sterility".