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Biomedical subjects

R H Potter

Publications and source records attributed to R H Potter.

At least 19 recordsLinked to original sources
PubMed1997

Angiogenesis and osteogenesis in an orthopedically expanded suture.

The purpose of this study was to examine the angiogenic and the subsequent osteogenic responses during a 96-hour time-course after sutural expansion. Fifty rats were divided into: (1) a control group that received only angiogenic induction through injection of 5 ng/gm recombinant human endothelial cell growth factor (rhECGF); (2) an experimental group that received orthopedic expansion and rhECGF; (3) a sham group that received expansion and sodium chloride (NaCl) injection; and (4) a baseline group that received no expansion or injection. All rats were injected with 3H-thymidine (1.0 microCi/gm) 1 hour before death to label the DNA of S-phase cells. Demineralized sections (4 microm thick) were stained with hematoxylin and eosin. Angiogenesis and cell migration were analyzed with a previously established cell kinetics model. Analysis of variance was used to test the hypothesis that enhancement of angiogenesis stimulates reestablishment of osteogenic capability. Blood vessel number, area, and endothelial cell-labeled index significantly increased in experimental groups, but no difference was found between control and baseline groups. Labeled-pericyte index and activated pericyte numbers in the experimental group were also higher than in the sham groups. These results show that supplemental rhECGF enhances angiogenesis in expanded sutures but not in nonexpanded sutures. Data also suggest that pericytes are the source of osteoblasts in an orthopedically expanded suture.

Analysis of Variance↗
PubMed1996

Angiogenic induction and cell migration in an orthopaedically expanded maxillary suture in the rat.

The purpose was to examine the effect of an angiogenic factor on cell migration patterns and osteoblast histogenesis during the 96 h following orthopaedic expansion of the anterior maxillary suture. Fifty rats were divided into four groups: (1) a control group that received only angiogenic induction via injection of 5 ng/g body wt recombinant human endothelial-cell growth factor; (2) an experimental group that received orthopaedic expansion and angiogenic induction; (3) a sham group that received orthopaedic expansion and normal saline injection; and (4) a baseline group that received no expansion or injection. The experimental and sham groups were subdivided to conduct experiments over 1, 2, 3 or 4 days. The anterior portion of each maxilla was dissected free and demineralized. Sections (4 microns thick) were cut from every block and stained with Mayer's haematoxylin and eosin. Cell migration was analysed using a previously established cell-kinetics model. The osteoprogenitor cells were divided into four categories according to nuclear volume: A cells (40-79 microns3), B cells (80-119 microns3), C cells (120-169 microns3) and D cells (> or = 169 microns3 A' cells are the portion of the A cell population that responds to osteogenic stimulus. As previously defined in periodontal ligament, the reciprocal association of a decreasing number of less differentiated (A + A) cells and an increasing number of C + D cells, as a function of distance from the nearest major blood vessel, was consistently found in all groups. This suggests a vascularly oriented gradient of progressively more differentiated osteoprogenitor cells. Also, A + A' cells were predominately located within 20 microns of the nearest major blood vessel whereas the C + D cells were found at a distance > 30 microns from the nearest major blood vessel. These results suggest that the A'-->C shift occurs 20-30 microns from the nearest major blood vessel. In the angiogenic induction groups, the numbers of committed osteoprogenitors (A + A') were significantly higher than in the sham group at day 1. At day 3, the numbers of preosteoblasts (C + D) in angiogenic sutures were significantly higher than in the sham groups. This enhancement of preosteoblast population strongly suggests the possible role of activated pericytes in expanded sutures as a source of osteoprogenitor cells.

Analysis of Variance↗
PubMed1995

Statistical analysis of differential lissajous EMG from normal occlusion and Class III malocclusion.

The method of differential lissajous electromyography (DL-EMG) was applied to investigate the relationship among the integrated EMG activity, timing, and coordination of the bilateral superficial anterior temporal and masseter muscle activities in normal occlusion and Class III malocclusion subjects. In both Class III malocclusion and normal occlusion subjects, the working side muscles showed a higher mean cumulative voltage (MCV) and mean maximum peak voltage (MMPV) compared with the balancing side. In addition, a higher MCV and MMPV of the working side masseter was observed in the normal occlusion group compared with that seen in the Class III group during both right and left side chewing (p < 0.01). Discriminant analysis applied to examine the distribution, the size and the shape of DL-EMG pattern further indicated a statistical difference between subject groups (p < 0.01). Finally, there was a significantly higher percentage of clockwise DL-EMG pattern-generation in the normal group compared with that seen for Class III subjects (p < 0.01). These data indicate that, compared with normal subjects, patients with a Class III malocclusion have a demonstrably abnormal masticatory muscle balance which is well characterized by the DL-EMG method.

Adolescent↗
PubMed1994

The effect of sleep on conscious sedation.

This study evaluated the effect of preoperative sleep on the success of conscious sedation. Thirty healthy children between the ages of 18 and 61 months of age were utilized in this study. The children all received chloral hydrate (50-60 mg/kg) and hydroxyzine (15-25 mg) and nitrous oxide (30-50%). Parents were asked to complete a questionnaire which asked several questions about their child's activity the previous day, their diet, and questions that related to their bedtime. The operator ranked the sedations on a scale from 1 to 4 with 1 being good and 4 being poor. The results were then statistically evaluated using the non-parametric Mann-Whitney and Kruskal-Walls tests. The children that received a normal amount of sleep or greater amount of sleep preoperatively had a borderline (P = .06) higher degree of successful sedation. There was no correlation between the child's bedtime (early, normal, late) and the success of sedation. The parent's perception of their child's tiredness could not be correlated with the success of the sedation. The children greater than 36 months of age had a significantly (P = .02) higher degree of successful sedations. The results suggest that a well rested child may experience a more pleasant dental sedation while under chloral hydrate and hydroxyzine conscious sedation and that the child's age at the time of the sedation may affect the outcome of the sedation.

Age Factors↗
PubMed1993

Triamcinolone acetonide versus chlorhexidine for treatment of recurrent stomatitis.

This study compared the efficacy of pain control of two medications, used to treat recurrent aphthous stomatitis, placed under a physical barrier of cyanoacrylate. Thirty patients with recurrent aphthous stomatitis were selected from the records of the Diagnostic Referral Clinic at Indiana University School of Dentistry and randomly divided into three groups; one group was a control. Experimental groups received a topical application of either triamcinolone acetonide (0.025%) or chlorhexidine digluconate (0.12%). Medications were covered by isobutyl cyanoacrylate (Iso-Dent). Controls received the Iso-Dent only. Patients kept a diary to record their pain level on a 10 cm visual analog scale until the lesion healed. Ulcer episodes were treated for 12 weeks. Because some patients had multiple episodes, a total of 35 ulcer episodes were available for analysis. The mean number of ulcer days for each group was not significantly different. ANOVA with repeated measures for 10 days on each patient was first performed. A highly significant difference in pain intensity and perception was found at different days (p < 0.0001). No significant difference was found between the triamcinolone acetonide and chlorhexidine gluconate (p < 0.49).

Adolescent↗
PubMed1990

Twin half-sibs: a research design for genetic epidemiology of common dental disorders.

Dental caries and the chronic type of periodontal disease are classic examples of common familial diseases that are complex and multifactorial in etiology. Due to previous methodological limitations, there is no information at present on the genetic and shared environmental risks within families that account for familial aggregation of these diseases. Such information, however, is needed in the long run to help specify modifiable family environments that affect the frequency and/or severity of the disease, and thereby to aid in the planning of prevention strategies to be targeted at the family level. Recently, an innovative genetic model has been described to test the genetic and environmental basis of chronic familial diseases in identical (monozygotic) twins, their spouses, and their offspring, who are genetically half-sibs. In this paper, the method is detailed and shown to be appropriate not only for partitioning shared genetic and environmental risks within families, but also for delineating maternal effects and assortative mating as two non-genetic mechanisms that may ultimately be found to affect the incidence of disease.

Analysis of Variance↗
PubMed1988

Comparison of meclofenamate sodium and hydrocortisone for controlling the postsurgical inflammatory response in rats.

The effectiveness of meclofenamate sodium and hydrocortisone in alleviation of local postsurgical swelling and leukocytic infiltration was compared at two postsurgical intervals in 60 male Sprague-Dawley rats. Both drugs were effective at 24 hours after surgery. Ten doses of 2 mg meclofenamate sodium administered over a 5-day period were more effective in reducing leukocytic infiltration than six doses of 2 mg hydrocortisone administered over the same period. Neither the hydrocortisone nor the meclofenamate sodium at the dosage used adversely affected osteoid formation.

Animals↗
PubMed1986

Comparative genetic variance and heritability of dental occlusal variables in U.S. and Northwest Indian twins.

Genetic variance analysis of 15 dental occlusal and arch variables is based on cross-cultural comparison of twin variances (U.S. Whites and Northwest Indian Punjabis). Both samples exhibit high genetic versus environmental partition of variance. However, monozygotes and dizygotes have unequal variance, which invalidates conventional genetic variance ratios. The pattern of environmental biases on the zygosities is quite different in the two groups. Revised estimates that acknowledge zygosity heterogeneity (hence unequal environmental influences) are generally much lower for occlusal traits, whereas arch size measurements are unaffected.

Adolescent↗
PubMed1985

Use and application of structural models in dental education research.

The notion of prediction implies causation. Path and structural models explore the causal links rather than mere empirical relationships between variables. This technique involves a breakdown of correlations; it differs from correlation and regression methods in that it provides relevant information in the presence of important but unobserved (latent) explanatory variables and of measurement errors in the data. It also allows for more than one regression analysis simultaneously and affords inference through tests of the model. In this study, latent abilities of dental students were analyzed as causes and professional achievements as effects, with preadmission performances as indicators of latent abilities. A model with three constructs is consistent with the observed data. The results demonstrate that whereas correlation analysis presents limitations in interpretation, structural analysis focuses clearly on the direct impact of the quality of dental school education, rather than preadmission background, on clinical performance and board success as measures of future professional performance.

Aptitude↗
PubMed1983

The dental morphology of Pima Indians.

Fourteen morphologic crown traits were observed in a sample of 1528 Pima Indians of south-central Arizona. Pima dentitions are characterized by high frequencies of shoveling, incisor winging, the hypocone, the lower canine distal accessory ridge, cusp 6, and the protostylid. They exhibit low frequencies of the metaconule and lower premolar multiple lingual cusps and moderate frequencies of the canine tubercle, Carabelli's trait, cusp 7, and lower second molars with four cusps and X groove patterns. When Pima crown trait frequencies were compared to those of 13 Southwest Indian samples, their closest affinities were to other Uto-Aztecan groups, the Papago and Hopi. The Pima are most divergent from Athapaskans and are also clearly removed from Yuman speaking groups and the Zuni. In general, the pattern of dental morphologic variation in the Southwest corresponds closely to linguistic divisions.

Arizona↗
PubMed1983

Dental size traits within families: path analysis for first molar and lateral incisor.

Previous works on the inheritance of dental traits have traditionally followed Fisher's model for family data under the assumption that phenotypic similarity between relatives is due solely to genetic factors. This study uses recent causal models that incorporate the contribution of nonrandom environmental sources of variation to familial resemblance on dental size. Path analysis was applied to observed interclass and intraclass correlations of sex-specific parent-offspring and sib pairs in 293 Pima Indian families from the southwest United States. The mesiodistal dimension of an early-forming and stable tooth (first molar) was contrasted with a late-forming and variable tooth (upper lateral incisor) for genetic and familial environmental components of variation. Parameters were estimated according to the XTAU models of Rice et al. (1980) and linear constraints placed upon the parameters were tested. The proportion of variance accounted for by genetic and environmental transmissible factors is estimated to be 52% for the first molar and 35% for the lateral incisor. Neither X-linkage nor sex-specific environmental effects are required to explain the transmission of dental size. Nontransmissible environmental effects that account for sibling correlations are detectable. Furthermore, sex differences are found in correlated sibling environments for the lateral incisor but not the first molar, to explain in part male-female differences in the distributions of the upper lateral incisor size.

Female↗
PubMed1983

Fluctuating asymmetry in molar dimensions and discrete morphological traits in Pima Indians.

Asymmetry in mesiodistal and buccolingual crown diameters and in eight morphologic crown traits of permanent first and second molars was analyzed in a large Pima Indian sample. Analysis of antimeric differences indicates no consistent evidence for directional asymmetry in Pima molars for either dimensions or morphologic traits. Second molars show greater degrees of metric and morphologic asymmetry than first molars. There is no conclusive evidence for either sex differences in magnitude of asymmetry or relationships between tooth size and morphologic asymmetry. Nonparametric correlations computed between asymmetry in crown dimensions and morphological traits show no significant interaction except where morphological trait development affected crown measurements. The distributions of antimeric differences for dimensional and morphologic traits demonstrate significant leptokurtic deviations from normality. This indicates fluctuating asymmetry in Pima Indians may result from several different sources of developmental variation.

Arizona↗
PubMed1983

Changing occlusal variation in Pima Amerinds.

Occlusal variables and arch measurements have been recorded on 341 Pima Amerinds pertaining to two samples, one of older individuals raised on traditional diets, the other of younger individuals raised on refined commercial foods that are typical of modern urbanized people. Permanent dental occlusion is significantly more variable from defined ideals in the younger sample, despite their fewer deformities resulting from progressive aging. The youths had relatively narrower palates, correlating with a general trend among industrialized populations and also among experimental animals fed soft diets. Relative rate of deciduous tooth loss and replacement did not correlate with any occlusal variable.

Adult↗