Examination of phacoemulsification tips after different numbers of cataract surgeries.

To compare unused phacoemulsification tips and those used different times with different techniques of cataract surgery (divide and conquer and chop), in vivo phacoemulsifications were performed with tips of different numbers of operation. These were compared with the same number of sterilized-only and unused tips with the help of an atomic force microscope. Comparison of roughness values (Sa, Sq), geometric and measurable flange length and surface was also performed (profile length %, area %). The differences between the parameters that can be measured during surgery (average ultrasound percentage, US ave %, Average Phaco Time, APT) were also analyzed. We found significant correlations between age and lens hardness (p = 0.0045), area % and APT (p = 0.03), between area % and US ave% (p = 0.03) and also between the two surgical techniques in terms of area% (p = 0.04) and US ave % (p < 0.01). Roughness increased with the number of uses. An increase in profile length% can be observed up to the twentieth operation. This can result from scratches and microscopic damages and also from abrasion and possible material additions on the surface of the needles. The divide and conquer technique causes less microscopic damage to the surface, and smaller average US energy is required during surgery.

Single-cell level LasR-mediated quorum sensing response of Pseudomonas aeruginosa to pulses of signal molecules.

Quorum sensing (QS) is a communication form between bacteria via small signal molecules that enables global gene regulation as a function of cell density. We applied a microfluidic mother machine to study the kinetics of the QS response of Pseudomonas aeruginosa bacteria to additions and withdrawals of signal molecules. We traced the fast buildup and the subsequent considerably slower decay of a population-level and single-cell-level QS response. We applied a mathematical model to explain the results quantitatively. We found significant heterogeneity in QS on the single-cell level, which may result from variations in quorum-controlled gene expression and protein degradation. Heterogeneity correlates with cell lineage history, too. We used single-cell data to define and quantitatively characterize the population-level quorum state. We found that the population-level QS response is well-defined. The buildup of the quorum is fast upon signal molecule addition. At the same time, its decay is much slower following signal withdrawal, and the quorum may be maintained for several hours in the absence of the signal. Furthermore, the quorum sensing response of the population was largely repeatable in subsequent pulses of signal molecules.