The fit of fixed partial dentures joined by infrared soldering.

This study determined the accuracy of fit of three-unit fixed partial dentures joined by an infrared soldering technique compared with one-piece fixed partial denture castings and individually cast crowns. Wax patterns of prepared Ivorine teeth, maxillary left central incisor and maxillary left canine, were injection molded; a plastic rod was used as a pontic. One group of patterns was cast as one-piece dentures; the other group was sectioned in the connector area, cast individually and then joined by infrared soldering. Castings were seated on their respective dies, embedded in epoxy resin, and sectioned. Gap distances between the casting and the die were measured at specified marginal sites with a profile projector. Results showed that the fit of infrared-soldered fixed partial dentures was significantly better than that of one-piece castings and was comparable with the fit of single crowns. The gap openings measured in all castings were within the range of clinical acceptability.     

Ovum recovery after microsurgical reanastomosis of the rabbit oviduct

Causes for failure of pregnancy after tubal reconstructive surgery are incompletely understood. The impact of microsurgical resection reanastomosis on ovum recovery was studied in the rabbit oviduct. One hundred sixty rabbits were divided into three groups: one experimental group in which a resection reanastomosis was made in the ampullar or isthmic tubal segment, respectively, and two control groups. After mating, ovum recovery was evaluated. In ampullary operated oviducts the ovum recovery rate was significantly lower compared with recovery rates in isthmically operated and in control oviducts. Furthermore, in ampullary operated oviducts peritoneal transmigration of ova was frequently observed. Disturbances in ovum pickup from the ovarian surface or the peritoneal cavity seem to be responsible for the decrease in recovery rate found in the ampullary operated oviducts.     

The effect of laser refractive surgery on the on-field performance of professional baseball players.

BACKGROUND: The aim of this study was to determine the effect of laser refractive surgery on the offensive performance of professional baseball players. METHODS: Extensive search of the public media was conducted to determine which major league baseball players had undergone laser refractive surgery and when the procedure was performed. Baseball performance data were then used to determine presurgery and postsurgery baseball performance averages. A total of 17 position players were identified; however, 5 of these players were not considered in the analysis owing to insufficient playing experience either before or after the laser procedure. RESULTS: No statistically significant or practically significant difference was found between the presurgery and postsurgery means on either on-base percentage (P = 0.31), batting average (P = 0.39), slugging percentage (P = 0.66) or on-base plus slugging (OPS; P = 0.997) of major league baseball players. CONCLUSIONS: These preliminary findings suggest that professional baseball players should not expect a laser refractive surgical procedure to significantly improve their offensive baseball performance, despite the elimination of glasses or contact lens wear.     

Ventilatory criteria for aeromedical evacuation

Ventilatory requirements during simulated aeromedical transportation were investigated in normal dogs and animals with oleic acid-induced lung injury. Inspired oxygen fractions of 0.21 and 1.0 were used to ventilate the normal and injured dogs, respectively. Both groups were ventilated with a constant-volume piston ventilator. After a control period, animals were exposed to a simulated altitude of 8,000 ft (barometric pressure 564 mm Hg), followed by a second control period at ground level. Both groups of animals had no change in carbon dioxide production, arterial PCO2 or ventilation during exposure to reduced barometric pressure. Systemic blood pressure, heart rate, cardiac output, and lung volume were all lower in oleic acid-injured animals than controls; the alveolar-arterial oxygen difference was larger in the oleic acid group. With altitude exposure, arterial and mixed venous oxygen tensions were decreased in both groups. Adequate gas exchange can be maintained during exposure to altitude even in animals with abnormal function provided that ventilation is constant and the inspired oxygen fraction is increased to compensate for the reduced barometric pressure.