The Americleft Project: A Comparison of Short- and Longer-Term Secondary Alveolar Bone Graft Outcomes in Two Centers Using the Standardized Way to Assess Grafts Scale.

OBJECTIVE: To compare length of follow-up and cleft site dental management on bone graft ratings from two centers. DESIGN: Blind retrospective analysis of cleft site radiographs and chart reviews for determination of cleft-site lateral incisor management. PATIENTS: A total of 78 consecutively grafted patients with complete clefts from two major cleft/craniofacial centers (43 from Center 1 and 35 from Center 2). INTERVENTIONS: Secondary iliac crest alveolar bone grafting, at a mean age of 9 years 9 months (Center 1: 9 years 7 months; Center 2: 10 years 0 month). MAIN OUTCOME MEASURES: The Americleft Standardized Way to Assess Grafts scale from 0 (failed graft) to 6 (ideal) was used to rate graft outcome at two time points (T1, T2). Average T1 was 11 years 1 month of age, 1 year 3 months postgraft. Average T2 was 17 years 11 months of age, 8 years 0 months postgraft. Six trained and calibrated raters scored each radiograph twice. Reliability was calculated at T1 and T2 using weighted kappa. A paired Wilcoxon signed rank test (P < .05) tested T1 and T2 differences for each center. A Kruskal-Wallis test was used to determine the significance of differences between centers at T1 and T2. Correlation tested whether T1 ratings predicted T2. Linear regression determined possible factors that might contribute to graft rating changes over time. RESULTS: Reliability was good at T1 and T2 (interrater = .713 and .701, respectively; intrarater = .790 and .805, respectively). Center 1 scores were significantly better than those from Center 2 at both T1 (5.21 versus 3.29) and T2 (5.18 versus 3.44). There was no statistical difference between T1 and T2 scores for either center; although, there was a greater chance of bone graft score improving with completion of canine eruption and substitution for missing lateral incisors. CONCLUSIONS: Short-term ratings of graft outcomes identified significant differences between centers that persisted over time. Dental cleft-site management influenced final graft outcome.

A finite element analysis of the maxillary first molar PDL with maxillary protraction in a mixed dentition Class III malocclusion.

OBJECTIVES: To analyze the stress distribution on the PDL of the maxillary first molar in a mixed dentition Class III malocclusion, using a Hyrax-type appliance and maxillary protraction. SETTING AND SAMPLE POPULATION: A Class III malocclusion in the mixed dentition was reconstructed based on CBCT images. MATERIAL AND METHODS: The 3D FEM comprised the maxilla, alveolar bone, right first permanent molar teeth, and PDL and consisted of 1 133 497 nodes and 573 726 elements. Maxillary protraction force was applied to a hook positioned close to the deciduous canines with 600 g and at 15°, 30°, and 45° downward angles to the maxillary occlusal plane. RESULTS: Analysis was carried out from the top and buccal view of the sagittal plane. The magnitude of the stresses at 15°, 30°, and 45° of protraction angulation resulted in the highest stress magnitude being in the region between the distobuccal and palatal roots, as well as on the distal surface of the mesial root. The vector direction in this area showed traction and mesial movement. With 30° and 45° protraction angulations, the stress was located only between the distobuccal and palatal roots, and the vector direction was more extrusive at 15°. CONCLUSIONS: The suggested orthodontic movement is in the mesial direction with a small amount of extrusion with 15° angulation and greater extrusion with 30° and 45°.

Craniofacial features affecting mandibular asymmetries in skeletal Class II patients.

OBJECTIVES: The aim of this study was to evaluate the characteristics affecting different intensities of mandibular asymmetry in skeletal Class II adults using three-dimensional images. This study is clinically relevant since it allows professionals to evaluate the morphological components related to these deformities and more carefully obtain correct diagnosis and treatment plan for such patients. METHODS: Cone-beam computed tomography data of 120 Class II patients (40 with relative symmetry, 40 with moderate asymmetry, and 40 with severe asymmetry) were imported to SimPlant Ortho Pro® 2.0 software (Dental Materialise, Leuven, Belgium). Three reference planes were established and linear measurements were performed from specific landmarks to these planes, comparing the deviated side and the contralateral side in each group, as well as the differences between groups. The correlation between midline mandibular asymmetry and other variables was also evaluated. Statistical analyses considered a significance level of 5%. RESULTS: Comparing the values obtained on the deviated side and on the contralateral side, there were significant differences for patients with moderate asymmetry and severe asymmetry. However, differences were seen more often in severe mandibular asymmetries. In those patients, there was a significant correlation of the gnathion deviation with lower dental midline deviation, difference in the lateral gonion positions, difference in the mandibular rami heights, and difference in the jugale vertical displacements. CONCLUSIONS: For skeletal Class II patients with mandibular asymmetry, some craniofacial features are related to chin deviation and require proper evaluation, including the bilateral differences in the ramus height, mandibular body length, transverse and vertical positioning of the gonion and jugale points.

High-resolution imaging of gigahertz polarization response arising from the interference of reflected surface acoustic waves.

The surface polarization caused by traveling SAWs at 1.585 GHz has been imaged using a dynamic homodyne electrostatic force microscope technique. Instead of measuring topographic changes caused by the SAW, the reported technique measures polarization in the piezoelectric substrate arising from mechanical stress caused by the SAW. The polarization associated with this stress field modulates the scanning probe cantilever deflection amplitude, which is extracted using a lock-in-based technique. High-resolution imaging is presented with images of the interference arising from a metal reflector on a SAW device. A mathematical model combining SAW generation and force interactions between the probe and the substrate was used to verify the experimental data. In addition to overcoming the challenge associated with detecting and imaging polarization effects at gigahertz frequencies, this imaging technique will greatly assist the development of SAW-based devices that exploit the reflection and interference of SAWs in areas as diverse as microfluidic mixing, cell sorting, and quantum entanglement.

VisioTracker, an innovative automated approach to oculomotor analysis.

Investigations into the visual system development and function necessitate quantifiable behavioral models of visual performance that are easy to elicit, robust, and simple to manipulate. A suitable model has been found in the optokinetic response (OKR), a reflexive behavior present in all vertebrates due to its high selection value. The OKR involves slow stimulus-following movements of eyes alternated with rapid resetting saccades. The measurement of this behavior is easily carried out in zebrafish larvae, due to its early and stable onset (fully developed after 96 hours post fertilization (hpf)), and benefitting from the thorough knowledge about zebrafish genetics, for decades one of the favored model organisms in this field. Meanwhile the analysis of similar mechanisms in adult fish has gained importance, particularly for pharmacological and toxicological applications. Here we describe VisioTracker, a fully automated, high-throughput system for quantitative analysis of visual performance. The system is based on research carried out in the group of Prof. Stephan Neuhauss and was re-designed by TSE Systems. It consists of an immobilizing device for small fish monitored by a high-quality video camera equipped with a high-resolution zoom lens. The fish container is surrounded by a drum screen, upon which computer-generated stimulus patterns can be projected. Eye movements are recorded and automatically analyzed by the VisioTracker software package in real time. Data analysis enables immediate recognition of parameters such as slow and fast phase duration, movement cycle frequency, slow-phase gain, visual acuity, and contrast sensitivity. Typical results allow for example the rapid identification of visual system mutants that show no apparent alteration in wild type morphology, or the determination of quantitative effects of pharmacological or toxic and mutagenic agents on visual system performance.

PA roles in a tertiary medical center.

This study describes the common elements of PA roles within tertiary medical centers, and compares physicians' perceptions of PA utilization with those of the PAs they supervise. The sample included 23 PAs employed by a university-based tertiary care center and a university-affiliated VA medical center. Variables examined included employment settings, patients seen, hours worked, and other job descriptors. Descriptions of the tasks performed by the PAs were also acquired. The results suggest that PAs employed in tertiary care settings contribute substantially to the provision and continuity of patient care, particularly in the area of patient education.

Practice characteristics of male and female physician assistants.

In a national survey of 3,294 non-military responding physician assistants, sociodemographic and practice characteristics of male and female physician assistants were compared. Differences by specialty, practice setting, size of community, and hours of work were generally similar in nature, but smaller in magnitude, than those reported for physicians, and may not be of practical significance.

Effect of inhibition of DNA synthesis on histone synthesis and deposition.

We have reinvestigated the degree of coupling between DNA and histone synthesis in mammalian cells. In at least one cell line (HTC cells), the coupling is not nearly as tight as had previously been inferred from experiments with HeLa cells. The site of deposition of such histones which continue to be made in the presence of sufficient hydroxyurea to depress DNA synthesis almost totally has been studied. Deposition seems to be on material which absorbs at 260 nm. This material is not a part of the bulk chromatin and binds histone in a relatively tight manner. The possible role of such a material in histone synthesis and deposition is discussed.

Evidence for a composite state of an F'his, gnd element and a cryptic plasmid in a derivative of Salmonella typhimurium LT2.

A method designed to select mutants constitutive for expression of the histidine operon has been applied to a Salmonella typhimurium LT2 strain containing an F'his,gnd element and a cryptic plasmid. One of the mutants isolated, strain AA0019, has not only increased levels of histidinol phosphate phosphatase (hisB), but also increased levels of gluconate-6-phosphate dehydrogenase (gnd). Ultracentrifugation studies of extrachromosomal deoxyribonucleic acid (DNA) isolated from strain AA0019 revealed the presence of a single species of covalently closed circular (CCC) DNA that sedimented more rapidly through neutral and alkaline sucrose gradients than any of its possible plasmid precursors. From neutral sucrose gradients, sedimentation coefficients of 130, 100, and 86S were derived, corresponding to the CCC DNA of the large plasmid in strain AA0019, the F'his,gnd element and the cryptic LT2 plasmid, respectively. An Escherichia coli plasmid-free strain that upon mating had received the large 130S plasmid also contained 86S and 100S CCC DNA components. A histidine-requiring derivative of strain AA0019 obtained after acridine orange treatment retained the cryptic plasmid DNA. Apparently, the large plasmid in strain AA0019 consists of the F'his,gnd element and the cryptic LT2 plasmid of the parental strain.

Analysis of plasmid deoxyribonucleic acid in a cariogenic strain of Streptococcus faecalis: an approach to identifying genetic determinants on cryptic plasmids.

Streptococcus faecalis strains ND539 and OG1 have been previously shown to be cariogenic in gnotobiotic animals. Deoxyribonucleic acid analyses have revealed the presence of a single 26-megadalton plasmid designated pAM539 in the former strain, whereas the latter strain was found to be plasmid-free. By gene transfer experiments, it was possible to construct isogenic pairs of strains that differed only with regard to the presence or absence of pAM539. Comparative studies of isogenic pairs showed that the presence of pAM539 conferred bacterial sensitivity to a bacteriocin produced by S. faecalis strain 5952.

Characterization of plasmids determining hemolysin and bacteriocin production in Streptococcus faecalis 5952.

Two plasmids designated pOB1 and pOB2 were isolated from Streptococcus faecalis strain 5952 and found to have molecular weights of approximately 46 X 10(6) and 28 X 10(6), respectively. pOB1 was found to determine hemolytic activity and was transmissible, whereas pOB2 appeared to determine a bacteriocin that is specifically inhibitory to S. faecalis strains harboring the 26-megadalton plasmid pAM539.

Medical practice revenue and salaries of physician assistants.

Significant salary differences between male and female PAs have been noted. Several variables--hours worked per week, weeks worked per year, number of patients seen per week, and average fee per patient--were examined to assess their contribution to the differences in salary for PAs practicing in family medicine, internal medicine, and pediatrics. Although female PAs were found to earn significantly less than their male colleagues, the discrepancy could largely be explained when salary was examined as a proportion of revenue generated for the practice. The survey findings are compared with research findings on male and female physicians' salaries.

Patients' satisfaction with physician assistant services.

Research on patient satisfaction with physician assistants in rural primary care medical practices is lacking. This study attempted to: determine patients' satisfaction with family practice PAs in rural communities, assess patient perceptions of "comfort" with PAs in a range of hypothetical medical procedures, analyze patients' reactions to PAs as a function of patient characteristics, and document perceptions of changes in medical practices after PAs are employed. Findings support reports that patients are highly satisfied with PA services and extends those observations to rural primary care practices. Reaction to PAs is more favorable among women, more favorable in patients with more education, and more favorable among those with greater contact with PAs.