Micropatterned, clickable culture substrates enable in situ spatiotemporal control of human PSC-derived neural tissue morphology.

We describe a modular culture platform that enables spatiotemporal control of the morphology of 2D neural tissues derived from human pluripotent stem cells (hPSCs) by simply adding clickable peptides to the media. It should be widely applicable for elucidating how spatiotemporal changes in morphology and substrate biochemistry regulate tissue morphogenesis.

Clinical application of a direct placement mercury-free alloy.

This article provides information about a recently introduced, mercury-free restorative alloy. This direct placement alloy uses gallium rather than mercury to mix the alloy particles. The material has recently been approved for use in the United States. Although its handling and physical properties are similar in most ways to amalgam, there are a few differences that require careful attention to assure success for the restoration. This article discusses these handling characteristics, the procedures for placement, and offers specific directions and recommendations to avoid potential problems with its use. Information on recent clinical research is included in the article.

Effects of two methods of moisture control on marginal microleakage between resin composite and etched enamel: a clinical study.

Visible light-polymerized resin composite tabs were bonded to the flattened, acid-etched surface of teeth that were scheduled for extraction. Half of the teeth (group I) were isolated with cotton rolls in conjunction with a saliva ejector. The remaining teeth (group II) were isolated using a rubber dam. Both methods of isolation were used for each patient so that to some extent all patients served as their own controls. Following extraction, all samples were thermocycled 500 times alternating between 6 degrees C and 60 degrees C, after which they were immersed in 5% methylene blue for 4 hours. Each tooth was then mounted in acrylic resin and sectioned on a hard tissue microtome. Microleakage was assessed using a light microscope at x 20 magnification. The use of rubber dam isolation resulted in less microleakage at the enamel resin interface.

Comparing two methods of moisture control in bonding to enamel: a clinical study.

Twelve patients provided a total of 36 teeth to be used in this study. Visible-light-cured composite resin tabs were applied to a flattened, acid-etched surface of each tooth. Half of the teeth were isolated with cotton rolls in conjunction with a saliva ejector; the other conjunction with a saliva ejector; the other half were isolated using a rubber dam. An equal number of teeth were treated in each group for each subject to serve as a self-control. After extraction the teeth were mounted and shear bond strength of the composite resin to enamel was determined on an Instron Testing Machine. There was a significant difference in the shear bond strength between the two experimental groups.

Effectiveness of nitric-NPG as a conditioning agent for enamel.

This in vitro study was designed to measure the bond strength of composite resin to enamel treated with various regimes of HNO3-NPG (N-phenylglycine and glycidylmethacrylate) followed by application of PMDM (pyromellitic dianhydride and 2-hydroxyethyl methacrylate). Forty freshly extracted human teeth were prepared with a flat area entirely in enamel on the proximal surface and then divided into five groups. Group 1 was treated with 37% H3PO4, Group 2 with 2.5% HNO3-NPG while rubbing the enamel with the solution, Group 3 with 2.5% HNO3-NPG without rubbing, Group 4 with 37% H3PO4 plus 2.5% HNO3-NPG with rubbing, and Group 5 with 5% HNO3-NPG without rubbing. After drying, PMDM solution was applied to each specimen for 60 seconds. Unfilled resin was applied, cured for 20 seconds, and the composite resin was placed and cured from all sides for a total of 120 seconds. After water bath storage for 7 days, specimens were tested on an Instron machine at a crosshead speed of 2.0mm/min. The highest shear bond strengths measured were for Group 1 (22.7 MPa), followed by Group 2 (20.92 MPa). The lowest bond strength recorded was for Group 3 (14.43 MPa). The results of this study indicate that enamel surfaces treated with 2.5% HNO3-NPG solution, if the solution is rubbed during application, produce a bond strength comparable to that achieved by H3PO4 conditioning.

Comparison of the effects of D-(-)-ephedrine and L-(+)-pseudoephedrine on the cardiovascular and respiratory systems in man.

1 In a preliminary double-blind trial the effects of ephedrine and pseudoephedrine on the blood pressure and heart rate of resting healthy volunteers were compared. Ephedrine 60 or 90 mg were required to raise the diastolic blood pressure above 90 mmHg, whereas 210 or 240 mg pseudoephedrine were required to produce the same effect. 2 In a second double-blind trial, patients with reversible airways obstruction were given 60 mg ephedrine or 210 mg pseudoephedrine and the effects on forced expiratory volume in one second (FEV1) compared. Both isomers produced some bronchodilation, but the effect of pseudoephedrine was less than half that of ephedrine. 3 The reasons for these differences between the isomers are discussed and the efficacy of pseudoephedrine as a nasal decongestant pointed out and explained in relation to its effect on alpha-adrenoceptors in the nasal blood vessels.