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Biomedical subjects

C E Meyers

Publications and source records attributed to C E Meyers.

At least 19 recordsLinked to original sources
PubMed2000

Treatment of a Class I bimaxillary protrusive malocclusion with a high mandibular plane angle: An American Board of Orthodontics case report.

A case report of the orthodontic treatment of a male adolescent with a Class I bimaxillary protrusive malocclusion, complicated by a vertical growth pattern and high mandibular plane angle. Treatment consisted of extraction of maxillary second premolars, mandibular first premolars, use of a transpalatal bar, occipital pull headgear, and light wire mechanics. An acceptable result was achieved, with a decrease in the facial axis, decrease in lip strain, and an attractive full smile. This case report was presented to the American Board of Orthodontics in partial fulfillment of the requirements for the certification process conducted by the Board.

Bicuspid↗
PubMed1995

A three-dimensional comparison of condylar position changes between centric relation and centric occlusion using the mandibular position indicator.

The mandibular position indicator (MPI) was used to compare condylar position between centric relation (CR) and centric occlusion (CO) for 107 patients before orthodontic treatment. The MPI data were examined to determine frequency, direction, and magnitude of CO-CR difference; and data were analyzed for possible correlation to the patient's Angle classification, ANB angular measurement, age, or gender. Only one patient (0.9%) had no measurable CO-CR difference in all three spatial planes. Six subjects (5.6%) showed a shift in condylar position in the transverse plane without a measurable difference in the sagittal plane. Twenty patients (18.7%) experienced a superoinferior (SI) or anteroposterior (AP) condylar displacement of at least 2.0 mm on one or both sides; 17 (15.9%) displayed a transverse shift at the level of the condyles of 0.5 mm or greater. No statistical difference was found between the 31 patients with Class I malocclusions and 72 patients with Class II malocclusions when comparing the amount or direction of CO-CR change. The amount of CO-CR difference was nearly identical for right and left sides with the amount of SI displacement (x = 0.84 mm) consistently greater than AP displacement (x = 0.61 mm). Only weak correlations were found between movements of right and left condyles. The average transverse CO-CR difference was 0.27 mm. Patient age, ANB angle, gender, or Angle classification cannot be used to predict frequency, magnitude, or direction of CO-CR changes at the level of the condyles.

Adolescent↗
PubMed1993

Effect of suramin on the mitogenic response of the human prostate carcinoma cell line PC-3.

BACKGROUND: Suramin is an anthelmintic drug that recently has been shown to have clinical efficacy in the treatment of patients with some advanced malignancies, including prostate carcinoma. The current study was done to assess the effect of suramin at clinically relevant doses on the growth in culture of a human prostatic carcinoma cell line, PC-3. METHODS: The antiproliferative effect of varying doses of suramin on PC-3 was assessed. Northern blot analysis was done to assess the potential changes in genetic expression at different times after the initiation of treatment. RESULTS: Suramin inhibited the proliferation of PC-3 in a dose-related manner (concentration range, 30-300 microM). Compared with fetal calf serum 2%, when the cells were grown in fetal calf serum 10%, higher concentrations of suramin were required to inhibit tritiated thymidine incorporation. When grown in RPMI without supplement, the PC-3 cell number remained the same. When 100 microM suramin was included, the cell number decreased. By contrast, when RPMI was supplemented with insulin, transferrin, and selenium (ITS), PC-3 grew well. The inhibition of the proliferation of PC-3 cells by suramin was decreased when ITS were added to the cells grown under serum-free conditions. CONCLUSIONS: These results were consistent with the hypothesis that in vitro inhibition of the growth of PC-3 cells by suramin may be caused, at least in part, by the growth factor antagonism of the drug. In fetal calf serum 2%, the suramin inhibition was reversible after 3 days. If the treatment was extended to 6 days, however, the PC-3 cells were unable to recover. Cell-cycle analysis revealed that, after 6 days of treatment, there was a decrease in the number of cells in G1 that corresponded with an increased number of cells in G2/M. This suggested that critical antineoplastic events were occurring during this time. Molecular analysis did not detect any altered expression of actin, transforming growth factors alpha or beta, or histone compared with untreated control samples.

Blotting, Northern↗
PubMed1992

Comparison of the shear bond strength of a light-cured glass ionomer and a chemically cured glass ionomer for use as an orthodontic bonding agent.

Light-cured glass ionomers with an initial set of 20 seconds may produce higher initial bond strengths, as well as decreased sensitivity to moisture contamination and desiccation, than chemically cured glass ionomers making them attractive for use as orthodontic bonding agents. The purpose of this study was to determine and compare the shear bond strength of stainless steel orthodontic attachments to enamel with a light-cured glass ionomer (Zionomer) tested at 60 minutes and 24 hours, and a rapidly setting chemically cured glass ionomer (Ketac-Bond) tested at 60 minutes and 24 hours. Fifty-two recently extracted human premolars were randomly divided into four groups--1-hour and 24-hour light-cured glass ionomer groups and 1-hour and 24-hour chemically cured glass ionomer groups. Stainless steel lingual buttons were bonded to prepared enamel surfaces, and the samples were placed in a water bath at 37 degrees C until ready for testing. The shear bond strength of each sample was determined with a universal testing instrument. Results from the study conclude: (1) The mean shear bond strength of the light-cured glass ionomer is greater than that of the chemically cured glass ionomer at 1 and 24 hours. (2) The mean shear bond strength of both glass ionomers increases from 1 to 24 hours. (3) The mean shear bond strength of the light-cured glass ionomer is not significantly different from 1 to 24 hours, but the shear bond strength of the chemically cured glass ionomer cement is different.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1990

Ceramic bracket bonding: a comparison of bond strength with polyacrylic acid and phosphoric acid enamel conditioning.

The purpose of this study was to compare in vitro shear bond strength with three different enamel surface preparations: (1) 37% phosphoric acid etch, (2) sulfated polyacrylic acid etch with removal of crystals by vigorous rinsing and (3) polyacrylic acid etch with crystal growth. Forty extracted human premolar teeth were divided into four groups of ten. Ceramic brackets were bonded to teeth in each of three groups. The fourth group used was bonded with metal brackets and a phosphoric acid enamel preparation. The same lightly filled resin cement was used for all groups. A shearing force was applied to the teeth. The results demonstrated that the shear force needed to debond with ceramic brackets was 21% greater than the shear force with metal brackets. The polyacrylic acid crystal growth group had shear bond strength values approximately one half as great as the phosphoric acid etch group when ceramic brackets were used. Bond failures in the phosphoric acid etch group were at the bracket/resin interface with the bulk of the resin remaining on the tooth compared with the polyacrylic acid crystal growth group in which the bond failure was at the enamel resin interface. Enamel fractures were not found when healthy nonrestored teeth were subjected to the shearing force. In a preliminary test using phosphoric acid etch and teeth with compromised enamel (large restorations involving three or more surfaces), half of the teeth fractured during debonding. The study demonstrated that a polyacrylic acid conditioning of the enamel surface produces different retentive surfaces, depending on the presence or absence of crystal growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid Etching, Dental↗
PubMed1990

The effect of hydrogen ion concentration on the force-degradation rate of orthodontic polyurethane chain elastics.

The effect of pH on the force-degradation rates of seven commercial orthodontic polyurethane chain elastics was evaluated in an in vitro study. The pH values of 4.95 and 7.26 were selected for testing because they represent values close to the reported extremes of plaque and saliva pH. Seven test elastic products were extended to (1) equal distances and (2) equal initial force levels, and the force-degradation rates were recorded over 4 weeks. All the test products yielded a significantly greater force-decay rate in the basic (pH 7.26) solution than in the acidic (pH 4.95) solution over 4 weeks. A hypothesis is presented that the decay rate of orthodontic polyurethane chain elastics is inversely proportional to the oral pH, with a corollary that basic pH levels are most hostile to polyurethane chain elastics.

Analysis of Variance↗
PubMed1987

Effects of suramin on the function and structure of the adrenal cortex in the cynomolgus monkey.

There have been reports of adrenal failure in patients treated with suramin, an agent that has recently been used as therapy for acquired immune deficiency syndrome. We conducted this study to assess the effect of suramin on adrenal function and structure in a primate, the cynomolgus monkey. Five male monkeys were treated with suramin (800 mg/m2, im) once a week, for 5 weeks. Five other animals (controls) received saline. The treated animals had progressive elevations of plasma ACTH (P less than 0.05) and PRA (P less than 0.02) and decreased serum cortisol responses 30 min after the administration of synthetic ACTH (P less than 0.05) compared to controls. There was disruption of the architecture of the adrenal cortex, a diffuse inflammatory cell infiltrate, and thinning of the zona glomerulosa and zona fasciculata in the suramin-treated animals. We conclude that suramin is toxic to adrenal cortical tissue and might be useful in treating conditions with adrenal cortical hyperfunction, such as adrenal cortical carcinoma and Cushing's syndrome.

Adrenal Cortex↗
PubMed1987

Characteristics of home environment of families with mentally retarded children: comparison across levels of retardation.

To help fill the relative void of information about families of severely mentally retarded school children, we described 53 such families comparatively with 54 families of EMR and 50 of TMR children. All children resided in their natural homes; families were selected for study by identical means and interviewed at their home. Selection for comparison was made from larger samples to reduce mean age differences in the samples. Differences in age and SES among groups were controlled with analysis of covariance. The impact of the retarded child on adjustment of families with severely retarded children was greater than that of the other groups, but no differences occurred in the impact of the child on marital adjustment. Families with severely retarded children had the highest mean scores on all four scores of the Home Quality Rating Scale. They scored lower than others on the Cohesion, Independence, Moral-Religious Emphasis, and Organization subscales of the Family Environment Scale. Implications for assisting these families were discussed.

Child↗
PubMed1986

Toxicity studies of adjuvant intravenous versus intraperitoneal 5-FU in patients with advanced primary colon or rectal cancer.

Clinical studies were prospectively conducted to quantitate the toxic side-effects of 5-FU administered by either the intravenous (i.v.) or intraperitoneal (i.p.) route. Sixty-six patients were treated following resection of a primary large bowel cancer after randomization to receive 5-FU by i.p. or i.v. routes. In both groups of patients, the dose of drug was increased a fixed amount until a toxic response occurred. At this point, the dose of drug was maintained or reduced in an attempt to complete 12 monthly treatment cycles of chemotherapy. The overall mean dose of drug administered by the i.p. route (1,479 mg) was significantly greater than given i.v. (1,019 mg), as it was for each treatment cycle. The primary adverse side-effect, resulting in drug dose stabilization or reduction, was leukocyte suppression of i.v. 5-FU or physical symptoms (abdominal pain or discomfort) for i.p. 5-FU (p2 = 0.0006 and p2 = 0.0318, respectively). The most frequent symptom reported by all patients was fatigue. Even though i.v. 5-FU dose was titrated to reduce toxicity, the nadir leukocyte count was suppressed over all cycles. The total numbers of immediate and delayed serious complications that resulted from i.v. or i.p. 5-FU were similar, although the nature of these complications differed markedly between the two routes of drug administration. Failure to complete 5-FU chemotherapy was significantly more common if patients received i.v. 5-FU plus pelvic irradiation. These studies indicate that intraperitoneal 5-FU administration decreases systemic drug effects even when the i.p. drug dose is increased to cause local toxicity.

Colonic Neoplasms↗
PubMed1985

Prospective, randomized trial of intravenous versus intraperitoneal 5-fluorouracil in patients with advanced primary colon or rectal cancer.

No new chemotherapy agents have been developed recently that present hope for improving survival in patients with colon or rectal cancer. We undertook this study to investigate a new route of administering an old drug, 5-fluorouracil (5-FU). Sixty-six patients with advanced primary colon or rectal cancer were randomized to receive 12 cycles with increasing dosages of intravenous (IV) or intraperitoneal (IP) 5-FU; the mean follow-up time was three years. The maximal tolerable dose and objective adverse side effects were prospectively recorded. The mean daily dose of 5-FU given by the IV route was 904 mg; for the IP route it was 1361 mg (p2 less than 0.0001). Two of ten patients had recurrent peritoneal carcinomatosis when treated with IP 5-FU; ten of eleven patients treated with IV 5-FU developed peritoneal implants (p2 less than 0.003). The incidence of serious complications was the same, but hematologic toxicity and hepatic toxicity were significantly reduced in patients who received IP 5-FU. When 5-FU is delivered by the IP route, the tolerable dose of drug was markedly increased without an increase in adverse side effects. The natural history of surgically treated disease was changed by reducing the incidence of peritoneal carcinomatosis but time to relapse and survival was not improved. IP 5-FU may be recommended for investigation in patients with perforated colon cancer, peritoneal implants, or as one part of a multimodality treatment protocol for colorectal cancer. If 5-FU is given to patients with gastrointestinal malignancy, the IP route should be strongly considered.

Adult↗
PubMed1985

Place of residence by age, ethnicity, and level of retardation of the mentally retarded/developmentally disabled population of California.

California's data on their mentally retarded/developmentally disabled population, the largest set in the United States, were accessed to determine residency of clients by age, ethnicity, and level of retardation. Data on the desired variables were available for over 59,000 of the 64,000 clients in the records. Despite claims of excess institutional population and the availability of residential alternatives, 52.5% of all persons resided in their natural homes; small family care units held 14.2% of the population and institutions, 12.8%, these being the second and third among the eight types of residences identified by the state. The proportion of the population in the natural home decreased with age and level of retardation, dropping precipitously among profoundly and severely impaired persons. Anglo-white families kept fewer (44%) at home than did blacks, Latinos, and other ethnic groups combined.

Black or African American↗
PubMed1984

Predicting retarded students' short-term growth from home environment.

This investigation sought to determine whether change in mentally retarded students' developmental status and adjustment could be predicted by variables of the psychological home environment for periods of one and two years. Over 120 trainable mentally retarded (TMR) and over 220 educable mentally retarded and educationally handicapped (EMR-EH) children were subjects. Annual interviews were conducted in the homes. Environmental data consisted of the Caldwell HOME (for TMR) or Henderson HELPS (for EMR-EH), the Moos Family Environment Scale, and the Home Quality Rating Scale. Eight dependent student variables included three factor scores of the Adaptive Behavior Scale as indicators of developmental status. Five adjustment scores included the two maladaptive scores from the Adaptive Behavior Scale and impact on family, psychological adjustment and social adjustment scores. First year student scores were partialled out to permit prediction of second and third year scores from first year environment scores. Stepwise multiple regression showed that environmental variables significantly improved R2 for all eight student scores in the second year and six to eight in the third year for the TMR group and six of eight in the second year and all eight in the third for the EMR-EH group. Data were interpreted to favor a concept of parent-child relationships as a continuously interactive phenomenon.

Adolescent↗
PubMed1984

Taxonomy of family life styles: II. Homes with slow-learning children.

A battery of instruments dealing with family social environment and family and child characteristics and behavior was administered to 218 families with slow-learning children in EMR and educably handicapped programs. Cluster analysis was performed on family environment variables. Seven unique family clusters, each with distinctive patterns of characteristics, were identified: child-oriented, cohesive; learning-oriented, high residential quality; low disclosure, unharmonious; disadvantaged, noncohesive; achievement-oriented, low residential quality; expression-oriented with few sociocultural interests; and outerdirected with little achievement-orientation. Comparisons among the clusters and ethnographic/interviewer observations revealed significant differences in other family and child characteristics and behavior. Development of a classification system for families with retarded children was discussed.

Achievement↗
PubMed1983

A review of attachment formation and disorder of handicapped children.

Research pertaining to attachment formation of handicapped children against a backdrop overview of the general attachment literature was examined. Attachment development and disorder of handicapped populations was reviewed categorically by handicap and by the procedures used to study attachment and analogous behavior with populations of handicapped children. In general, evidence to date suggests that attachment between young handicapped children and their mothers or caretakers may be delayed, dulled, or even absent. Some critical methodological issues were discussed, and implications of the study of attachment for developing theory, providing services, and understanding child abuse were delineated.

Child Abuse↗