Reduction of calcified plaque volume in ex vivo pericardial tissue, with nanobubbles.

The present research investigated the effect of nanobubbles in Ringer's solution on calcified plaque within ex vivo coronary and peripheral artery tissue. The goal of the work was to determine whether nanobubbles generated using an alternating magnetic field (AMF) system can reproducibly reduce the size of plaque obstructions in ex vivo pericardial tissue specimens compared to that in an untreated control. Nanoparticle tracking analysis (NTA) measurements were used to first confirm that AMF can produce nanobubbles in Ringer's solution as well as it does in water. Experiments were performed in which ex vivo human coronary artery and peripheral artery tissues containing plaque were exposed to Ringer's solution with and without the presence of AMF generated nanobubbles. Measurements on intravascular optical coherence tomography (IVOCT) images consistently indicated that plaque volume is significantly reduced in the presence of nanobubbles. A theory of induced dissolution by nanobubble/nanoparticle cluster formation provides a causal explanation for the observed reductions in plaque size.

Tooth intrusion in implant-assisted prostheses.

STATEMENT OF PROBLEM: Numerous reports and surveys have been published on natural tooth abutment intrusion with implant-connected fixed partial dentures. The consensus of these publications was that the cause of intrusion was multifactorial, with causative factors such as disuse atrophy, debris impaction, impaired rebound memory, and mechanical binding. It was also believed that the process was irreversible. PURPOSE: In this article, the limitations with these theories are discussed, and two patient reports of tooth intrusion reversal are reviewed. A review of the current literature is discussed, as well as the current theory of tooth movement in response to dynamic mechanical stimulus, a brief discussion of current experimental procedures and results, and the current recommendations for reversal of intrusion.

Axenic aerobic biofilms inhibit corrosion of SAE 1018 steel through oxygen depletion.

Corrosion inhibition of SAE 1018 steel by pure-culture biofilms of Pseudomonas fragi and Escherichia coli DH5 alpha has been evaluated in complex Luria-Bertani medium, seawater-mimicking medium, and modified Baar's medium at 30 degrees C. In batch cultures, both bacteria inhibited corrosion three to six fold compared to sterile controls, and the corrosion was comparable to that observed in anaerobic sterile media. To corroborate this result, a continuous reactor and electrochemical impedance spectroscopy were used to show that both P. fragi K and E. coli DH5 alpha decreased the corrosion rate by 4- to 40-fold as compared to sterile controls; this matched the decrease in corrosion found with sterile medium in the absence of oxygen and with E. coli DH5 alpha grown anaerobically. In addition, the requirement for live respiring cells was demonstrated by the increase in the corrosion rate that was observed upon killing the P. fragi K biofilm in continuous cultures, and it was shown that fermentation products do not cause an increase in corrosion. Hence, pure-culture biofilms inhibit corrosion of SAE 1018 steel by depleting oxygen at the metal surface.

Importance of biofilm formation for corrosion inhibition of SAE 1018 steel by axenic aerobic biofilms.

To investigate if corrosion inhibition by aerobic biofilms is a general phenomenon, carbon steel (SAE 1018) coupons were exposed to a complex liquid medium (Luria-Bertani) and seawater-mimicking medium (VNSS) containing fifteen different pure-culture bacterial suspensions representing seven genera. Compared to sterile controls, the mass loss in the presence of these bacteria (which are capable of developing a biofilm to various degrees) decreased by 2- to 15-fold. The extent of corrosion inhibition in LB medium depended on the nature of the biofilm: an increased proportion of live cells, observed with confocal scanning laser microscopy (CSLM) and image analysis, decreased corrosion. Corrosion inhibition in LB medium was greatest with Pseudomonas putida (good biofilm formation), while metal coupons exposed to Streptomyces lividans in LB medium (poor biofilm formation) corroded in a manner similar to the sterile controls. Pseudomonas mendocina KR1 reduced corrosion the most in VNSS. It appears that only a small layer of active, respiring cells is required to inhibit corrosion, and the corrosion inhibition observed is due to the attached biofilm.