Swimming behavior of the multicellular magnetotactic prokaryote 'Candidatus Magnetoglobus multicellularis' near solid boundaries and natural magnetic grains.

The magnetotactic yet uncultured species 'Candidatus Magnetoglobus multicellularis' is a spherical, multicellular ensemble of bacterial cells able to align along magnetic field lines while swimming propelled by flagella. Magnetotaxis is due to intracytoplasmic, membrane-bound magnetic crystals called magnetosomes. The net magnetic moment of magnetosomes interacts with local magnetic fields, imparting the whole microorganism a torque. Previous works investigated 'Ca. M. multicellularis' behavior when free swimming in water; however, they occur in sediments where bumping into solid particles must be routine. In this work, we investigate the swimming trajectories of 'Ca. M. multicellularis' close to solid boundaries using video microscopy. We applied magnetic fields 0.25-8.0 mT parallel to the optical axis of a light microscope, such that microorganisms were driven upwards towards a coverslip. Because their swimming trajectories approach cylindrical helixes, circular profiles would be expected. Nevertheless, at fields 0.25-1.1 mT, most trajectory projections were roughly sinusoidal, and net movements were approximately perpendicular to applied magnetic fields. Closed loops appeared in some trajectory projections at 1.1 mT, which could indicate a transition to the loopy profiles observed at magnetic fields ≥ 2.15 mT. The behavior of 'Ca. M. multicellularis' near natural magnetic grains showed that they were temporarily trapped by the particle's magnetic field but could reverse the direction of movement to flee away. Our results show that interactions of 'Ca. M. multicellularis with solid boundaries and magnetic grains are complex and possibly involve mechano-taxis.

Moistening the new vaginal misoprostol tablets: does it increase the efficacy of cervical priming before manual vacuum aspiration in first-trimester miscarriage? A randomised clinical trial.

OBJECTIVES: The primary objective of our study was to ascertain whether moistening the Brazilian formulation of vaginal misoprostol tablets increases cervical dilation before manual vacuum aspiration (MVA), compared with use of dry misoprostol, in first-trimester miscarriage. The secondary objective was to ascertain whether there was any correlation between vaginal pH and the degree of cervical dilation using a moistened or dry misoprostol tablet. METHODS: In a single-centre, double-blind, randomised trial, 46 patients with first-trimester miscarriage were randomly allocated to treatment with dry or moistened (with 200 µl distilled water) 2 × 200 µg misoprostol tablets. RESULTS: The median (range) cervical dilation in the wet and dry groups was 8 mm (6-12 mm) and 7 mm (5-10 mm), respectively (p = .06). The median time between misoprostol insertion and carrying out the procedure did not differ between the dry (406 min, range 180-550 min) and wet (448 min, range 180-526 min) groups (p = .1). No correlation was found between vaginal pH and cervical dilation using continuous data (p = .57; r= 0.08; 95% confidence interval -0.02, 0.3) or dichotomous data (pH ≤5/>5; cervical dilation ≥8 mm or <8 mm; p = .8). CONCLUSION: No difference was observed in cervical dilation between moistened and non-moistened misoprostol use prior to MVA.