Biomedical subjects

C Phillips

Publications and source records attributed to C Phillips.

At least 181 records · Page 10Linked to original sources

PubMed1993

Recovery following orthognathic surgery: mandibular bilateral sagittal split osteotomy and Le Fort I osteotomy.

Thirty-eight patients, who underwent orthognathic surgery, reported their recovery period upon returning to work or school and returning to full activity. Twenty-six patients had isolated bilateral sagittal split osteotomies (BSSO) and 12 had isolated Le Fort I osteotomies (LFI). At 1 to 2 weeks postoperatively, 50% of the BSSO group had returned to work or school while none of the LFI group had returned. By 3 to 4 weeks, 81% of the BSSO group had returned to work or school while nearly one half of the LFI group still had not returned. The BSSO group returned to full activity earlier than the LFI group, although the differences were not statistically significant. Hemoglobin, hematocrit, weight, and vital signs were determined preoperatively and for 6 weeks postoperatively. The LFI group had a larger mean estimated blood loss, length of operation, and weight loss.

Absenteeism↗

PubMed1993

Cephalometric measures as indicators of facial attractiveness.

Orthodontic treatment is frequently undertaken to improve facial appearance. However, the contribution of the components of malocclusion to perceptions of attractiveness is not clear. This study uses three panels of judges--undergraduates, dental students, and orthodontic residents--to quantify the associations between common objective measures of dental and skeletal anteroposterior disproportion and subjective perceptions of facial attractiveness. Consistent and similar correlations between anteroposterior measures and facial attractiveness rankings are shown for all three panels, with overjet being most strongly associated with rankings of attractiveness.

Adolescent↗

PubMed1992

Soluble anti-mu monoclonal antibodies prime resting B cells to secrete immunoglobulins in response to interleukins-4 and -5.

Soluble anti-immunoglobulin (Ig) antibodies have been generally found to inhibit Ig secretion in B cells, via largely unknown mechanisms. To investigate this phenomenon further a two-step culture system was used in which B cells are primed for 24-72 h with various soluble monoclonal or polyclonal anti-Ig antibodies: after washing the cells were placed in readout cultures with a combination of interleukin (IL)-5 and IL-4. Using this protocol B cells primed with (mitogenic or nonmitogenic) anti-mu monoclonal antibodies differentiated into large numbers of IgM-secreting cells, comparable to responses to lipopolysaccharide. In contrast, priming with polyclonal rabbit anti-Ig or monoclonal anti-kappa antibodies, markedly inhibited Ig secretion induced by IL-4 + IL-5. In addition, anti-mu was markedly inhibitory if left in the readout cultures with the two lymphokines. These results, therefore, indicate that appropriate cross-linking of surface IgM receptors on B cells can prime the cells to secrete Ig when they are restimulated by T cell-derived lymphokines in the absence of anti-mu. In contrast co-ligation of both surface IgM and surface IgD receptors apparently results in powerful inhibition of Ig secretion, which is not reversed by stimulation with IL-4 plus IL-5.

Animals↗

PubMed1992

Positional changes of the mandibular condyle assessed by three-dimensional computed tomography.

This investigation was designed to test the validity and reliability of three-dimensional computed tomography (3-D CT) for quantification of positional changes of the condyle in a laboratory model. The model consisted of a mounted dried human skull and a mandibular condyle attached to a micromanipulator. Controlled changes in condylar position were made and the condyle/fossa was imaged. Positional changes were measured by triangulation methods based on specific 3-D CT landmarks. The data were analyzed using descriptive statistics, analyses of variance to evaluate the sources of variability, and linear contrasts to evaluate the differences between observed and expected values. The results indicated that selection of appropriate anatomic landmarks for assessment of movement influences technique accuracy. The data also indicate that 3-D CT is most accurate in detecting inferior condylar movements. Lateral and posterior movements were assessed with less accuracy than the inferior positional changes. The clinical significance of these differences has yet to be determined.

Analysis of Variance↗

PubMed1992

The effect of treatment on facial attractiveness.

Pretreatment and posttreatment frontal and profile slides of 13 orthodontic camouflage and 13 orthognathic surgery patients were shown to three panels of judges: an orthodontic, an oral surgery, and a "lay" panel of first-semester dental students. Each judge rated the facial attractiveness of the pretreatment and posttreatment views of each patient using a visual analog scale. A mean pretreatment and posttreatment score was then calculated for each treatment group for each judge. Paired t tests were used to compare the treatment groups and time periods. The orthodontic camouflage group was rated as significantly more attractive than the orthognathic surgery patients before treatment. There was no significant change in the facial attractiveness mean score for the orthodontic group, whereas the orthognathic surgery group was rated as showing a significant improvement. However, the orthognathic surgery group was still rated as being significantly less attractive after treatment than the orthodontics-only group.

Adult↗

PubMed1992

Superior repositioning of the maxilla combined with mandibular advancement: mandibular RIF improves stability.

Postsurgical changes in 24 patients who had rigid internal fixation (RIF) of the mandible with screws after combined superior repositioning of the maxilla and mandibular advancement were compared with 53 patients who underwent the same surgery but who had intraosseous wire fixation, skeletal suspension wires, and 8 weeks of maxillomandibular fixation (MMF). During the first 8 weeks after surgery, the mean posterior relapse of the mandible was greater in the MMF group than in the RIF group (for example, -1.1 mm versus 0.15 mm at B point), and the percentage of patients with clinically significant vertical and horizontal changes was greater in the MMF group. By 1 year, there had been slight additional mean relapse in the MMF group (-1.5 mm net relapse at B point, with 42% of the patients showing 2 mm or more relapse). In the RIF group, the mandible was more likely to be repositioned forward than posteriorly (net mean change at B point, 0.7 mm forward; 33% had 2 mm or more forward movement). In the RIF group, all but one of the patients (96%) were judged to have an excellent clinical result; in the MMF group, the corresponding figure was 60%.

Adult↗

PubMed1992

A comparison of outcomes of orthodontic and surgical-orthodontic treatment of Class II malocclusion in adults.

The treatment outcome for skeletal Class II malocclusion was reviewed in 33 nongrowing patients who were treated with orthodontics alone (by premolar extraction and tooth movement to camouflage the skeletal problem) and in 57 patients treated for similar problems with surgery and orthodontics (with mandibular advancement and with tooth movement to reduce rather than increase dental compensation for the skeletal deformity). Cephalometric and dental cast changes were scored to quantitate treatment effects. Two approaches were used to determine the treatment efficacy (the relative success of treatment): (1) whether the final value for a measurement criterion (such as an overjet and an ANB angle) fell within the normal range, and (2) the quantitative amount of correction produced relative to an "ideal" value. In addition, a panel of judges was used to rate esthetic changes from pretreatment and posttreatment facial slides. Both orthodontic treatment and surgical-orthodontic treatment improved the malocclusion as judged from dental casts. Surgery resulted in greater reduction of overjet and greater improvement in most cephalometric skeletal, dental, and soft tissue criteria. Before treatment, the surgical patients had lower esthetic ratings than the orthodontics-only patients. After treatment, the esthetic ratings for the orthodontic patients were unchanged. The surgical patients had improved but not to the pretreatment level of the orthodontics patients.

Adult↗

PubMed1992

Stress, coping, and high-risk sexual behavior.

We examined the relation between stress, coping, and a high-risk sexual behavior (unprotected anal intercourse) in 398 nonmonogamous gay and bisexual men from the AIDS Behavioral Research Project in San Francisco. Unprotected anal intercourse during the previous month, the amount of stress experienced during the previous month in each of 10 domains, six types of coping (self-controlling coping, escape-avoidance, distancing, planful problem-solving, seeking social support, and positive reappraisal), and spiritual beliefs and spiritual activities were assessed through self-report. There was no relation between stress and unprotected anal intercourse. However, there was a relation between coping and unprotected anal intercourse. Subjects who reported unprotected anal intercourse used sex more of the time to help cope with stressful situations than did subjects who did not report unprotected anal intercourse. Unprotected anal intercourse was negatively associated with seeking social support and spiritual activities and positively associated with self-controlling coping, which involves keeping one's feelings to oneself, and positive reappraisal. The findings suggest that social aspects of coping may be a key to understanding differences between those who engage in high-risk sexual behavior and those who do not.

Adaptation, Psychological↗

PubMed1992

Rating of facial attractiveness.

Epidemiologic investigations of orthodontic treatment should include both objective clinical measures and elements of perceptual assessment in the definition of malocclusion and skeletal disproportion. The effect of dental training and the view of the face presented as a stimulus on judgments of facial attractiveness were evaluated using a method recommended by Howells & Shaw (1) for epidemiologic surveys. Three views (two full face and one profile) of 18 orthodontic patients were presented as stimuli to three panels of judges with different levels of dental training (16 orthodontic residents, 17 dental students, and 71 undergraduate students). Ratings for facial attractiveness were obtained using a visual analog scale. The visual analog scores given the series of 54 slides by each judge were then ranked to create a "location-free" outcome measure. Both the ratings and the rankings of these ratings differed significantly among the three views for 80% of the patients. However, no view was consistently rated or ranked as most attractive across all patients. The ordering of the views from least to most attractive for a given patient appears to be highly dependent on the patient being presented as stimulus. Future studies should consider showing multiple views of a subject simultaneously if the intent is to obtain an overall treatment need score that incorporates assessment of facial attractiveness. The patients were consistently rated as more attractive by the orthodontic residents than by either dental or undergraduate students. When the ranks were analyzed, there were significant differences between the panels but the consistent pattern of differences between the panels disappeared.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1992

Stability of surgical maxillary expansion.

Stability after transverse expansion of the maxilla via Le Fort I osteotomy with segments was evaluated in 39 patients. The average expansion was 5.4 mm at the second molars, decreasing almost linearly to 2.8 mm at the first premolars. Postsurgical relapse also was greatest at the second molars, averaging 2.6 mm. The percentage of relapse was greatest posteriorly, decreasing from 49% at the second molars to 30% at the first premolars. Considerable variability in stability followed surgery: Three-fourths of the patients had some relapse at the first molars (greater than 3 mm in 28%), but one fourth were stable. Sixty-two percent of the patients had a net posttreatment gain in arch width at the first molars. No correlation was found between transverse relapse and the type of presurgical orthodontic tooth movement, the use of rigid fixation, or the use of an auxiliary stabilizing arch wire. The amount of postsurgical relapse was significantly greater in those who had concurrent mandibular surgery. To improve clinical results with surgical expansion, we recommend (1) moderate overexpansion at surgery for major transverse changes, (2) maintenance of the occlusal splint for at least 6 weeks, and (3) use of a lingual arch wire or auxiliary labial arch wire to maintain molar width during postsurgical orthodontics.

Adult↗

PubMed1992

Surgical versus orthodontic correction of skeletal Class II malocclusion in adolescents: effects and indications.

To clarify the effects of orthodontic versus surgical treatment and to distinguish more clearly those Class II patients who can be treated successfully with orthodontics alone, we compared three groups of adolescents: forty patients treated successfully with orthognathic surgery, 40 patients treated successfully with orthodontics alone, and 21 patients whose orthodontic treatment was judged to be unsuccessful. Successful surgical treatment was accomplished largely by bringing the mandible forward, but this involved vertically repositioning the maxilla, alone or in combination with advancing the mandible, in 40% of the patients. Successful orthodontic treatment resulted from a combination of retraction of the maxillary incisors and protraction of the mandibular incisors; most of the successfully treated group also had significant vertical growth, and 40% had greater than 2 mm anteroposterior growth. The unsuccessfully treated orthodontic patients initially had greater overjet, more severe mandibular deficiency, and greater anterior facial height than those treated successfully; they also had less retraction of the maxillary incisors and less growth during treatment. In Class II adolescents beyond the growth spurt, surgery is likely to be needed for successful correction of the malocclusion if the overjet is greater than 10 mm, especially if the distance from pogonion to nasion perpendicular is 18 mm or more, mandibular body length is less than 70 mm, or facial height is greater than 125 mm.

Adolescent↗

PubMed1992

Recovery following orthognathic surgery and autologous blood transfusion.

Patients undergoing maxillary surgery, with or without mandibular surgery, were divided into two groups. One surgeon's patients served as controls and did not receive blood unless hemodynamically indicated. The remaining surgeons' patients were transfused regardless of their hemoglobin levels following surgery. An attempt was made to identify benefits or complications associated with the reinfusion of autologous blood, particularly in patients with "low blood loss." Patients were asked to record when they returned to their presurgical level of activity. Of the 46 patients in the study 14 (12 nontransfused, two transfused) were not back to full activity 6 weeks after surgery. Of the 32 patients that reported a return to full activity within the study period, transfused patients reported a significantly quicker return to full activity at 2 weeks, 3 weeks, and 4 weeks postoperatively than did their nontransfused counterparts, even when blood loss at surgery was minimal. No complications have occurred with this practice.

Adolescent↗

PubMed1992

Surgical-orthodontic correction of mandibular deficiency: five-year follow-up.

Changes in dental and skeletal relationships at 5 years postsurgery were evaluated in a group of 35 patients whose mandibular deficiency had been corrected by the same surgeon, using sagittal split osteotomy of the mandibular ramus. From 1 to 5 years postsurgery, there was a small (0.9-mm) but statistically significant mean decrease in mandibular length (condylion to point B). In six patients, the decrease in mandibular length was 2 to 4 mm, and in two it was more than 4 mm, but only one of these individuals had more than a 2-mm increase in overjet. There was no mean change in overjet, but three patients had a 2 to 4-mm increase. Of these, one had 3.2 mm shortening of the mandible, one had 1.4 mm shortening of the mandible, and one had no change in mandibular length but repositioning of the incisors. Most patients had a deep overbite initially, and there was a tendency for the bite to deepen between the first and fifth years postoperatively, more as a result of extrusion of incisors than of mandibular rotation. Remodeling of the gonial angle area, with vertical and/or horizontal repositioning of gonion, was noted in more than half the subjects. It appears that morphologic changes related to continued skeletal remodeling, often compensated for by small changes in mandibular posture or tooth positions, continue after 1 year postsurgery for many patients.

Adolescent↗

PubMed1991

The structure of 6-phosphogluconate dehydrogenase refined at 2.5 A resolution.

The three-dimensional structure of ovine 6-phosphogluconate dehydrogenase, refined at 2.5 A resolution with a residual for all data of 18.5%, is reported. This model, based on improved diffraction data and a corrected sequence, supersedes that reported earlier. Each subunit of the dimer has three domains: a beta-alpha-beta domain binds NADP; an all alpha domain provides much of the dimer interface; the C-terminal tail burrows into the second subunit.

Molecular Structure↗

PubMed1991

The t(1;22) (p13;q13) is nonrandom and restricted to infants with acute megakaryoblastic leukemia: a Pediatric Oncology Group Study.

We report the nonrandom occurrence and frequency of the t(1;22)(p13;q13) in acute myeloid leukemia (AML) and its close association with the French-American-British M7 subtype of AML in infants (less than 1 year). This chromosomal abnormality occurred in 6 of 252 (2.4%) children and adolescents with AML (6 of 28 infants, 22%; 6 of 18 M7 AML cases overall, 33%; and 6 of 6 M7 cases in infants). Infants with AML of M7 subtype and the t(1;22) often presented with prominent abdominal masses. Two of these infants were not treated and died early. Three of four treated infants entered complete remission with therapy for AML; the remaining infant died of hemorrhage on day 8. Of the three infants who entered remission, only one remains alive and disease free at 5+ months. The other two infants relapsed in the bone marrow at 5 and 2 months from the start of therapy, respectively. We conclude that M7 AML with the t(1;22) usually presents in infants with extensive infiltration of abdominal organs by leukemic cells and may confer a poor prognosis despite intensive AML-directed treatment. Identification of this nonrandom translocation exclusively in infants with acute megakaryoblastic leukemia (AMkL) implies that it may serve as an additional diagnostic marker for this disease and links it to the pathogenesis of AMkL in infants.

Antigens, CD↗

PubMed1991

Incidence of an estrogen receptor polymorphism in breast cancer patients.

We previously identified a polymorphism in the human estrogen receptor (ER) gene, within the coding region for the protein's amino terminal B-domain. In estrogen receptor-positive (ER+) breast tumors, the variant allele was preferentially associated with lower levels of ER, and was clinically correlated with frequent spontaneous abortions. DNA sequencing revealed a point mutation that changes codon 86 from Ala to Val and a silent mutation in codon 87. Because we initially detected the variant allele by analyzing RNA, only those tissues in which the ER gene is actively expressed were suitable for genotype analysis. We now describe an assay that uses genomic DNA as the substrate for determining the ER B genotype, DNA containing the polymorphic region of the ER gene is amplified by the polymerase chain reaction, then the amplified DNA is hybridized with radiolabeled oligonucleotide probes complementary to the wild type and variant ER alleles. This method allowed us to determine the ER B genotype of women with ER+ and ER- tumors, starting with minute amounts of DNA from frozen or paraffin embedded tissues. ER B genotyping was also performed on women without breast cancer using DNA extracted from blood cells. The combined results from analyses of RNA and DNA from 300 breast cancer patients showed that 12% were heterozygotes. In the ER+ group (n = 183), 11.5% carried the variant gene compared to 12.8% in the ER-negative group (n = 117) (chi 2 = 0.11; df = 1; p greater than 0.25).(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Neoplasms↗

PubMed1991

Induction of leukotriene production before antigen challenge enhances antibody affinity in genetically selected mice.

Mice genetically selected for their incapacity to produce high-affinity antibody to protein antigens in adjuvant (nonmaturing (NM) mice) were treated with indomethacin, an inhibitor of the cyclooxygenase pathway of arachidonic acid metabolism. Pretreatment with indomethacin significantly enhanced the affinity of antibodies produced 21 days after immunization with human serum albumin (HSA). Blockage of the cyclooxygenase pathway in this way was shown to induce the production of leukotrienes via the lipoxygenase pathway. The production of leukotrienes may well be responsible for the enhanced antibody affinity, since blockage of the lipoxygenase pathway in addition to the cyclooxygenase pathway reversed the effect. In an attempt to elucidate the mechanisms involved, IL-1 production and Ia expression by macrophages were examined. Ia expression by peritoneal cells from untreated NM mice was significantly lower than that by their high-affinity-producing counterparts 3 days after immunization. Indomethacin pretreatment raised inducible Ia antigen levels on macrophages of NM mice to those seen on cells from untreated high-affinity mice. Indomethacin treatment alone induced the production of IL-1 by macrophages in NM mice. However, 3 days after immunization and the withdrawal of indomethacin in NM mice, IL-1 production was significantly lower than the response of NM mice given antigen alone, suggestive of the induction of a feedback mechanism. Thus indomethacin pretreatment results in a cascade of events in macrophages which produce a decrease in IL-1 production and an increase in inducible Ia expression 3 days after antigen challenge.

Animals↗

PubMed1991

Validity of digital subtraction of transcranial plain films in quantification of positional changes of the mandibular condyle.

Condylar positioning problems have been associated with temporomandibular joint signs and symptoms. The position of the mandibular condyle is difficult to predict and quantify with existing routinely used radiographic techniques. An investigation was implemented to test the validity and reliability of digital subtraction to enhance transcranial plain films and to quantify positional changes of the condyle in a laboratory model. The model consisted of a mounted dried human skull and a mandibular condyle attached to a micromanipulator. Controlled changes in condylar position were made, and the condyle and fossa were imaged. The data were analyzed with descriptive statistics, analyses of variance to evaluate the sources of variability, and linear contrasts to evaluate the differences between observed and expected values. The results indicated that digital subtraction detected posterior positional change within 10% of the expected value. However, inferior positional changes were poorly detected and lateral positional changes could not be evaluated by this technique. We conclude that digitally subtracted transcranial radiographs may be useful for detection of posterior condylar movements, assuming that appropriate head-holding devices are used to fix x-ray source and head geometry.

Analysis of Variance↗