A liposomal hydrogel for the prevention of bacterial adhesion to catheters.

The adhesion of bacteria to medical implants and the subsequent development of a biofilm frequently results in the infection of surrounding tissue and may require removal of the device. We have developed a liposomal hydrogel system that significantly reduces bacterial adhesion to silicone catheter material. The system consists of a poly (ethylene glycol)-gelatin hydrogel in which liposomes containing the antibiotic ciprofloxacin are sequestered. A poly (ethylene glycol)-gelatin-liposome mixture was applied to a silicone surface that had been pre-treated with phenylazido-modified gelatin. Hydrogel cross-linking and attachment to surface-immobilized gelatin was accomplished through the formation of urethane bonds between gelatin and nitrophenyl carbonate-activated poly (ethylene glycol). Liposomal hydrogel-coated catheters were shown to have an initial ciprofloxacin content of 185+/-16 microg cm(-2). Ciprofloxacin was released over seven days with an average release rate of 1.9+/-0.2 microg cm(-2) h(-1) for the first 94 h. In vitro assays using a clinical isolate of Pseudomonas aeruginosa established the antimicrobial efficacy of the liposomal hydrogel. A modified Kirby-Bauer assay produced growth-inhibition zone diameters of 39+/-1 mm, while bacterial adhesion was completely inhibited on catheter surfaces throughout a seven-day in vitro adhesion assay. This new antimicrobial coating shows promise as a prophylactic and/or treatment for catheter-related infection.

A second generation training simulator for acquisition of psychomotor skills in cavity preparation.

Thirty freshmen dental students, without prior dental technique laboratory experience, were divided randomly into two groups of 15 subjects. One group (control) was trained in the traditional way while the other group used a newly developed dental training simulator. The results for Class I cavity preparations in the mandibular right first molar indicate that a two-thirds reduction in training time occurred for the group trained by the simulator as compared to the control group. The mean training times were 57 minutes for the control group and 21 minutes for the experimental group. No statistically significant differences in quality were noted.

Objective evaluation of quality in cavity preparations.

Significant improvements in reliability of criteria measures were obtained by using a newly developed instrument to evaluate objectively the quality of cavity preparations in comparison to subjective ratings by the instructors of the quality of cavity preparations.

Skills analysis of a class I amalgam restoration in a mandibular right first molar.

1. Students changed their body position 32% more often than instructors during amalgam condensation. 2. Experienced instructors used 38% fewer strokes than students to condense the amalgam. 3. On the average, instructors used 65% less time per condensation stroke than students. This was not due to ability to move the instrument more quickly, since both students and instructors had similar minimum stroke times, but rather to the fact that instructors performed slowly less often. 4. The upstroke during condensation required nearly the same time for both students and instructors (an eight percent difference). It was the downstroke that was greatly different (a 96% difference). 5. Instructors repeated condensation strokes 22% more often than students, working more systematically with less "jumping around" in the cavity. 6. The total number of carving strokes was not related to experience. 7. Students repeated carving strokes more often than instructors. 8. Students and instructors tended to use the same length of strokes in carving. 9. There was a noticeable difference between instructors and students in the method used to grasp the instruments.

Improving evaluation of amalgam restorations.

A predictive model of overall quality of performance is presented which might assist both dental students and dental faculty by increasing the reliability of clinical and laboratory evaluations. Training effectiveness can be improved by identification of those restorative skills which contribute most to the quality rating of restoration.

Epidemiology of acute rheumatic fever in a multiethnic, multiracial urban community: the Miami-Dade County experience.

During the mid-1980s, several US communities experienced outbreaks of acute rheumatic fever (ARF), often involving predominantly white, middle-class individuals living in suburban or rural settings. The medical records of all patients diagnosed with ARF in Miami-Dade County, Florida, between 1984 and 1988 were reviewed. Thirty-five cases met the revised Jones criteria and were considered definite; four additional cases were classified as probable. Carditis was present in 54%. Of the 39 patients, 32 (82%) were black. The annual incidence of ARF among black children aged 5-14 years was 12.25 per 100,000 compared to 0.71 for other (non-Hispanic white plus Hispanic) children (P less than .001). ARF was centered in the inner city, where the incidence among black children reached 15.21. Despite the multiethnic, multiracial character of Miami-Dade County and the rapid influx of immigrants, ARF in this community remains primarily a disease of underprivileged, black inner-city children.