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PubMed2005

The influence of water storage on durometer hardness of 5 soft denture liners over time.

PURPOSE: This laboratory study investigated the influence of water storage on the durometer hardness of 2 RTV and 3 HTV soft denture liners over a 1-year period. MATERIALS AND METHODS: Five soft denture liners were used: 2 HTV silicone rubber (Luci-Sof and Molloplast-B), 1 RTV silicone rubber (Tokuyama), 1 HTV polyphosphazene (Novus), and an RTV plasticized acrylic (PermaSoft) that uses a surface sealer. They were processed following manufacturers' instructions, cured, and stored in tap water at 37 degrees C. The water was changed every 2 weeks. Five durometer A hardness measurements were made at logarithmically spaced intervals of 16.7 minutes, 27.8 hours, 11.6 days, 34.7 days, 115 days, and 347 days. Repeated measures analysis of variance (MANOVA), one-way analysis of variance (ANOVA), Pillai trace statistic, the difference scores (last-first) among the groups, and the Tamhane T2 multiple comparison test were used to compare the groups over time, all on SPSS V. 7.5 and 9.0. RESULTS: The order of highest initial indentation hardness was Luci-Sof, Molloplast-B, Novus (H(D)= 38 to 33). Tokuyama and PermaSoft as a group were softer (H(D)= 18 to 22). Tokuyama Soft Relining changed the least over 347 days, followed by Luci-Sof, Novus, Molloplast-B, and PermaSoft in that order (p < or = 0.05). Within the PermaSoft group, sealer applied only once changed the least over 347 days, followed by no sealer, and then sealer applied every month (p < 0.0005). CONCLUSIONS: After 347 days of water storage, Tokuyama had the lowest indentation hardness changes, followed by Luci-Sof, Novus, PermaSoft with sealer applied once; Molloplast-B, PermaSoft without sealer; and PermaSoft with sealer applied every month. All HTV soft denture liners had higher indentation hardness than RTV liners initially. After 347 days, PermaSoft without sealer and with sealer every month became the hardest.

Analysis of Variance↗
PubMed2001

Do inhaled corticosteroids affect perception of dyspnea during bronchoconstriction in asthma?

BACKGROUND: Some of the disagreements on the perception of dyspnea (PD) during bronchoconstriction in asthma patients could depend on the interrelationships among the following: (1) the influence of baseline airflow obstruction on the patient's ability to detect any further increase in airway resistance; (2) the effect of eosinophilic inflammation on the airway; (3) bronchial hyperresponsiveness (BHR); and (4) the effect of inhaled corticosteroids (ICSs). OBJECTIVE: We hypothesized that if the inflammation of the airway wall influences to some extent and in some way the PD in asthma patients, ICSs reverse the effect of airway inflammation on the PD. METHODS: We studied 100 asthma patients who were divided into the following four groups: patients with obstruction who were either ICS-naive (group I) or were treated with ICSs (group II); and nonobstructed patients who were either ICS-naive (group III) or were treated with ICSs (group IV). PD on the visual analog scale (VAS) was assessed during a methacholine-induced FEV(1) decrease and specifically was quantified as the VAS slope and score at an FEV(1) decrease of 5 to 20%. BHR was assessed in terms of the provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)). Eosinophil counts in induced sputum samples also were performed. Regression analysis, univariate analysis of variance, and factor analysis were applied for statistical evaluation. RESULTS: For a 5 to 20% fall in FEV(1) from the lowest point after saline solution induction, VAS score was lowest in group II, slightly higher in group I, slightly higher still in group IV, and the highest in group III. In the patients as a whole, BHR related to PD, but age, clinical score, duration of the disease, and presence of baseline airway obstruction did not. In patients with obstruction who were treated with ICSs, eosinophil counts related to PD negatively. Factor analysis yielded the following four factors that accounted for 70% of the variance in the data: ICS; eosinophil counts; FEV(1); and PC(20) loaded on separated factors with PD loading on the same factors as PC(20). The post hoc analysis carried out dividing the patients into ICS-treated and ICS-naive, showed that in the former group eosinophil counts and BHR proved to be factors negatively associated with PD, while in the latter group eosinophil counts were positively associated with PD. CONCLUSIONS: We have shown that eosinophilic inflammation of the airway wall may increase PD and that the association of eosinophil counts with ICSs may result in lessening the PD.

Adolescent↗
PubMed1983

Kinetics of fluorine in deciduous enamel after application of fluoride-containing varnish (Duraphat). II. A statistical approach to the design and evaluation of a clinical experiment.

The aim of this report is to discuss the design and technique for evaluation of an in vivo experiment on the kinetics of fluorine in deciduous enamel after application of fluorine-containing varnish (Duraphat). The analysis of variance technique used in the analysis of the results of the experiments is described in more detail than in the preceding report. The figure technique used in this report series is described. The method error study performed before carrying out the main experiment is analysed. A brief discussion follows about the consequences that different method errors have on the design of the experiment. The conclusion is that analysis of variance is a more reliable tool than multiple t-test, when evaluation of experiments is to be carried out.

Analysis of Variance↗
PubMed2002

Resistance of core materials against torsional forces on differently conditioned titanium posts.

STATEMENT OF THE PROBLEM: The separation of core materials from titanium posts, which have a low modulus of elasticity, has been identified as a problem in restorative dentistry. PURPOSE: This study evaluated the resistance to torsional forces of various core materials adapted to differently conditioned titanium posts. MATERIAL AND METHODS: Seven hundred and twenty specimens were tested consisting of: 6 core materials and 5 surface conditioning techniques for 2 kinds of opaquers with 10 specimens in each group (6 x 5 x 2 x 10=600) plus 6 core materials and 2 opaquers were tested and considered as control groups on nonconditioned titanium posts, each group containing 10 specimens (6 x 2 x 10=120). The custom-made pure titanium posts were conditioned with the following products: Silicoater Classical, Silicoater MD, Rocatec, Kevloc, and Siloc surface-conditioning systems. Subsequently, 6 core materials with different compositions (Durafill, Adaptic, Coradent, Ti-Core, Hytac Aplitip, and Photac-Fil Aplitip) were applied to titanium posts that were previously coated with 2 types of light-polymerized opaquers, either Artglass or Dentacolor. Sixty air-abraded titanium posts (250 microm, 30 seconds) were used as controls for each core material. Following thermocycling (5 degrees -55 degrees C, 30 seconds, 5,000 cycles), maximum torsional forces were determined with an electronic torque movement key. Data were statistically analyzed by 1-way analysis of variance followed by 2-way analysis of variance (P<.05). RESULTS: Significantly higher mean torsional forces were observed with respect to Siloc (20.4 Newton decimeter [dNm]), Silicoater Classical (18.6 dNm), Silicoater MD (18.2 dNm), and Rocatec (17.0 dNm) systems compared with the mean for the untreated control group (14.6 dNm) (P<.001). The Kevloc system (10.4 dNm) demonstrated no significant difference compared with the control group (P>.001). The Kevloc system in combination with the Artglass opaquer and Photac-Fil Aplitip (0.00 dNm) core material showed no resistance against torsional forces. Significant differences were observed between hybrid core materials and microfilled composite, compomer, or resin-modified glass ionomer core materials (P<.001). CONCLUSION: Within the limitations of this study, the resistance to torsional forces for the core materials on titanium posts increased with the use of chemical surface-conditioning techniques and varied in accordance with the opaquer type. Type of core material also significantly influenced the resistance after thermocycling.

Acrylonitrile↗
PubMed1977

Psychometric modeling of consumer decisions in primary health care.

A psychometric technique, functional measurement, was used to measure the preferences of 77 persons for hypothetical health care providers identified by various levels of cost, travel time, and waiting time; responses were subjected to analysis of variance and graphic analysis to determine the functional relation by which respondents combined the three attributes in arriving at their preferences. Both modes of analysis suggested multiplicative decision models, but these yielded lower values of R2 than did linear models derived for comparison. Respondents were grouped by the proportion of response variance that was explained by each of the three attributes, and decision models were derived for each group. Discriminant analysis of socioeconomic characteristics of the respondents identified the variables that distinguished the groups and contributed to forming their preferences.

Community Participation↗
PubMed1982

Statistical analysis of effect of anoxia on rate of change of ventricular pressure.

Hearts from 32 male Sprague-Dawley rats were studied to determine effects of anoxia on ventricular contractility. Maximum rate of ventricular pressure changes with time (Pmax) were obtained from simultaneous recordings of right and left ventricular pressure curves. Peak aortic flow and heart rate were measured. Anoxia was produced by 100% N2 respiration. Statistical models were repeated-measures analysis of variance and randomized block factorial analysis of variance. Alpha was 0.05. Heart rate during anoxia was significantly lower than during the 1st min of recovery. Heart rate during both these periods was significantly lower than in preanoxia or the remainder of recovery. Peak aortic flow was not significantly altered. In left ventricles positive Pmax was significantly higher than negative Pmax. In right ventricles positive and negative Pmax were not significantly different. Left ventricular Pmax was significantly depressed during anoxia, whereas right ventricular Pmax was not. Significant differences in pressure developed per mass of tissue was a possible source of variation in right (0.12 +/- 0.002 mmHg/mg) and left (0.16 +/- 0.009 mmHg/mg) ventricular contractile maintenance.

Analysis of Variance↗
PubMed1997

Effects of chemical disinfectants on the surface characteristics and color of denture resins.

PURPOSE: Because dentures are disinfected repeatedly and for various amounts of time, it was of clinical interest to determine whether chemical disinfectants altered the surface texture or inherent color. MATERIAL AND METHODS: Five chemical disinfectants (Clorox, Banicide, Cidex-7, Biocide, and Multicide) in combination with five denture resins (Dentsply reline material, Hygenic HyFlo, Hygenic Perm, Lucitone 199, and Triad VLC reline resin) were evaluated at four different times of immersion (10 minutes, 30 minutes, 24 hours, and 7 days). Changes from baseline for surface roughness and color were recorded. Surface roughness data were recorded with a surface analyzer. Color data in CIE L*a*b* color space were measured with a colorimeter. Data were analyzed with repeated-measures analysis of variance and single-factor analysis of variance. RESULTS: Although statistical differences were demonstrated among disinfectants and resins for both measured parameters, the magnitudes of change in color and roughness was most often clinically insignificant. CONCLUSIONS: One disinfectant (Multicide) cannot be used on all five resins, and the remaining four disinfectants can be used on any of the five resins for up to a period of 30 minutes. All resins tested can be immersed in the four remaining disinfectants for up to 30 minutes without appreciable alteration to surface texture or color. Lucitone 199 resin can be immersed in any of the four disinfectants for up to 7 days without perceivable color change.

Acrylic Resins↗
PubMed2001

Measurement of thoracic and lumbar fracture kyphosis: evaluation of intraobserver, interobserver, and technique variability.

STUDY DESIGN: Statistical analysis of various measurement techniques for thoracolumbar burst fracture kyphosis on lateral radiograph. OBJECTIVE: To determine the most reliable measurement technique. SUMMARY OF BACKGROUND DATA: The treatment of thoracic and lumbar burst fractures involves many factors, including the degree of resultant kyphosis. Although various methods have been described, no study has directly compared these methods for reliability and reproducibility. METHODS: Fifty lateral radiographs of thoracic and lumbar burst fractures were randomly selected and measured on two separate occasions by three spine surgeons using five different measurement techniques. Radiograph quality, fracture type, and the center beam location were determined. Statistical analysis included analysis of variance for repeated measures and analysis of variance using a generalized linear model. RESULTS: Intraclass correlation coefficients were most consistent for Method 1 (rho = 0.83-0.94) followed by Method 4 (rho = 0.65-0.89) and Method 5 (rho = 0.73-0. 85). Intraobserver agreement (% of repeated measures within 5 degrees of the original measurement) ranged between 72% and 98% for all techniques for all three observers, with Method 1 showing the best agreement (84%-98%). Paired comparisons between observers varied considerably with interobserver reliability correlation coefficients ranging from 0.52 to 0.93. Method 1 showed the highest interobserver reliability coefficient (0.81, range 0.71-0.93) followed by Method 5 (0.71, range 0.68-0.75). Method 1 also had the highest percentage of agreement within categories (90% within 5 degrees ). CONCLUSIONS: Method 1 (measuring from the superior endplate of the vertebral body one level above the injured vertebral body to the inferior endplate of the vertebral body one level below) showed the best intraobserver and interobserver reliability overall.

Analysis of Variance↗
PubMed1999

Effect of a longitudinal course on student performance in clerkships.

OBJECTIVE: To determine the effect that a 3-year primary-care course experience with family medicine, internal medicine, or pediatric preceptors would have on clerkship performance in pediatrics and internal medicine. DESIGN: In 1 academic year, third-year students were divided retrospectively into 3 groups based on preceptor type in the primary care course. An analysis of variance was conducted. When the analysis of variance showed statistical significance, a multiple-comparison t test was performed. SETTING: University medical school with a longitudinal preceptor experience. PARTICIPANTS: One hundred nine third-year medical students who participated in the primary care course and completed the pediatric and internal medicine clerkships. Fifty-six students took part in the self-assessment portion of the study. MAIN OUTCOME MEASURES: Student performance scores in the pediatric clerkship and internal medicine clerkship were analyzed for significant differences based on preceptor type. Student self-assessment on pediatric objectives was analyzed for significant differences based on preceptor experience. RESULTS: Students with pediatric preceptors received higher clinical scores in the pediatric clerkship (P = .04) and perceived themselves as more advanced on 18 of the 39 pediatric curriculum pretest self-assessment items. Students with pediatric or internal medicine preceptors received significantly higher scores on the written patient medical history and physical examinations (P = .02). There were no significant differences on the pediatric written examination. There were no significant performance differences in the internal medicine clerkship. All hypothesis testing was conducted at the 95% confidence level. CONCLUSION: Experiences with pediatric preceptors in the early years of medical school may improve a student's performance and confidence in the pediatric clerkship.

Analysis of Variance↗
PubMed1995

Blood pressure responses of white men with hypertension to two low-sodium metabolic diets with different levels of dietary calcium.

OBJECTIVE: To compare the blood pressure responses of men with hypertension consuming low-sodium (Na) metabolic diets differing in dietary calcium (Ca) for two 6-week periods. SUBJECTS: White men who had hypertension, were nonsmokers, and were sedentary. INTERVENTION: This study consisted of two separate 6-week metabolic feeding periods. In the first period, a high-Ca group (n = 6) was fed 1,400 mg Ca per day. In the second period, a low-Ca group (n = 5) was fed 400 mg Ca per day. Both groups were fed 1,500 mg Na per day. MAIN OUTCOME MEASURES: Blood pressure; urine and blood measured for electrolyte, calcitriol, renin, and parathyroid hormone (PTH) levels. To measure typical nutrient intakes, 3-day dietary records were collected before the beginning of each treatment period. STATISTICAL ANALYSES PERFORMED: Repeated-measures analysis of variance and split-plot analysis of variance were used to analyze, respectively, blood pressure responses and response variables over time. RESULTS: In both groups, serum Na level decreased (P < .05) over the 6-week period; urine Na decreased (P < .05) only in the low-Ca group. Serum PTH level decreased (P < .05) in the high-Ca group and increased (P < .05) in the low-Ca group; no change occurred in serum calcitriol level. Diastolic blood pressure decreased (8 mm Hg) in the low-Ca group (P < .05). The low-Ca group showed an 8% to 9% decrease in both systolic and diastolic blood pressure vs a 2% to 3% decrease in the high-Ca group. We also examined how the metabolic diet differed from subjects' typical diet. Results showed a positive correlation between the change in Na intake (usual to metabolic diet) and the change in systolic and diastolic blood pressure in both groups (P < .04). Results also showed a negative correlation between the change in the ratio of Na to Ca (usual to metabolic diet) and the change in diastolic blood pressure in the low-Ca group (P < .03). Directional change in blood pressure (either increase or decrease) could be predicted on the basis of how much the Na and Ca in the metabolic diet differed from subject's typical diet. APPLICATIONS: Results of this study suggest that in the dietary management of hypertension it may be more important to focus on specific changes in a person's diet (eg, decreasing Na intake by 1,000 mg/day and increasing Ca intake by 400 mg/day) rather than setting specific levels of Na and Ca to be consumed.

Analysis of Variance↗
PubMed2004

The effect of LASIK on best-corrected high-and low-contrast visual acuity.

PURPOSE: To evaluate the effects of laser in situ keratomileusis (LASIK) and LASIK with concurrent astigmatic keratectomy (LASIK/AK) on high- and low-contrast visual acuity. METHODS: The setting was a university refractive surgery practice. Patients were recruited from those undergoing LASIK or LASIK/AK for myopia (>1.00 D spherical equivalent) between May 1996 and August 1997. All subjects were at least 21 years of age. Testing occurred preoperatively and 3 and 6 months after LASIK. Main outcome measures were best spectacle-corrected, high- and low-contrast visual acuity. RESULTS: For all subjects, there was a significant effect of surgery on nondilated low-contrast visual acuity (repeated measures two-way analysis of variance, p < 0.0001). Tukey's posthoc analysis showed that preoperative low-contrast visual acuity scores were significantly different from 3-month [0.08 logarithm of the minimum angle of resolution (logMAR)] and 6-month (0.11 logMAR) scores for patients undergoing LASIK and LASIK/AK. Under dilated conditions, there was a significant effect of surgery for high- and low-contrast visual acuity (analysis of variance, p < 0.0001 for both). Only changes in low-contrast visual acuity were clinically meaningful [LASIK, visual acuity reduction of 0.1 logMAR (1 line); LASIK/AK, visual acuity reduction of 0.15 logMAR (1.5 lines)]. When considering high and low myopes separately (LASIK only), the level of myopia had a significant effect on the visual acuity after surgery (analysis of variance, p = 0.01). Preoperative, dilated, low-contrast visual acuity scores for high myopes were significantly different from 3-month (0.14 logMAR) and 6-month (0.13 logMAR) scores. No differences were noted for low myopes. CONCLUSIONS: Clinically meaningful postoperative changes in low-contrast visual acuity were noted in patients undergoing LASIK and LASIK/AK under natural and dilated conditions. Postoperative, dilated, low-contrast visual acuity scores were significantly worse than preoperative scores for high myopes, but remained unchanged for low myopes.

Adult↗
PubMed2001

Association analysis in a variance components framework.

Association analyses conducted in a variance components framework can include information from all available individuals but remain unbiased in the presence of familiality or linkage. Models that include both linkage and association parameters provide different estimates of the effect of a single locus and can be used to distinguish causal polymorphisms from other types of variation. We examine some of these models and their properties in a blind analysis of the simulated Genetic Analysis Workshop 12 data sets.

Chromosome Mapping↗
PubMed1989

Variance estimation for medical decision analysis.

We have derived the variance of an expected utility for a probability tree in medical decision analysis based on a Taylor series approximation of the expected utility as a function of the probability and utility values used in the decision tree. The resulting variance estimate is an algebraic expression of the variances associated with the probability and utility estimates used. We also derive expressions for the case where the input parameter estimates are not independent. We discuss the choice of input parameters and their variance estimates and give an example that compares two protocols for the treatment of chlamydial infection.

Analysis of Variance↗
PubMed1996

Comparison of 2-year weight loss trends in behavioral treatments of obesity: diet, exercise, and combination interventions.

OBJECTIVE: The effects of three cognitive-behavioral weight control interventions for adults were compared: diet only, exercise only, and a combination of diet and exercise. This article reports 2-year follow-up data. DESIGN: The three interventions were compared in a randomized, experimental design. SUBJECTS: A total of 127 men and women who were at least 14 kg overweight (according to height-weight tables) were recruited from an urban community and assigned randomly to the experimental conditions. INTERVENTION: The dietary intervention was a low-energy eating plan adjusted to produce a 1 kg/week loss of weight. The exercise component involved training in walking and a home-based program of up to five exercise periods per week. There were 12 weekly instructional sessions, followed by 3 biweekly and 8 monthly meetings. All sessions were led by registered dietitians. OUTCOME MEASURES: Changes in body weight. STATISTICAL ANALYSES: Analysis of variance for weight changes and repeated measures analysis of variance for weight change trends. RESULTS: At 1 year, no significant differences were noted among the three groups. The diet-only group lost 6.8 kg, the exercise-only group lost 2.9 kg, and the combination group lost 8.9 kg (P=.09). During the second year, the diet-only group regained weight--reaching 0.9 kg above baseline; the combination group regained to 2.2 kg below baseline; and the exercise-only group regained slightly to 2.7 kg below baseline (P=.36). Repeated measures analysis of variance showed a group-by-time interaction (P=.001); data for the dieting groups best fit a U-shaped regain curve (P=.001). APPLICATIONS: The results suggest that dieting is associated with weight loss followed by regain after treatment ends, whereas exercise alone produced smaller weight losses but better maintenance. The large outcome variability and unequal difficulty of the regimens across groups limit the generalizability of the findings.

Adult↗
PubMed1997

Classification of collected trot, passage and piaffe based on temporal variables.

The objective was to determine whether collected trot, passage and piaffe could be distinguished as separate gaits on the basis of temporal variables. Sagittal plane, 60 Hz videotapes of 10 finalists in the dressage competitions at the 1992 Olympic Games were analysed to measure the temporal variables in absolute terms and as percentages of stride duration. Classification was based on analysis of variance, a graphical method and discriminant analysis. Stride duration was sufficient to distinguish collected trot from passage and piaffe in all horses. The analysis of variance showed that the mean values of most variables differed significantly between passage and piaffe. When hindlimb stance percentage was plotted against diagonal advanced placement percentage, some overlap was found between all 3 movements indicating that individual horses could not be classified reliably in this manner. Using hindlimb stance percentage and diagonal advanced placement percentage as input in a discriminant analysis, 80% of the cases were classified correctly, but at least one horse was misclassified in each movement. When the absolute, rather than percentage, values of the 2 variables were used as input in the discriminant analysis, 90% of the cases were correctly classified and the only misclassifications were between passage and piaffe. However, the 2 horses in which piaffe was misclassified as passage were the gold and silver medallists. In general, higher placed horses tended toward longer diagonal advanced placements, especially in collected trot and passage, and shorter hindlimb stance percentages in passage and piaffe.

Analysis of Variance↗
PubMed2004

Low-dose dual blockade of the renin-angiotensin system in patients with primary glomerulonephritis.

BACKGROUND: Treatment with agents interfering with the renin-angiotensin system retards the progressive course of proteinuric chronic renal disease. However, because of unwanted effects associated with such therapy, some patients cannot be treated with these drugs at all or may be administered only very small doses. To find an optimal nephroprotective strategy for these patients, we compared antiproteinuric effects of combination therapy with an angiotensin-converting enzyme inhibitor and angiotensin II type 1 receptor antagonist in very small doses with treatment with either agent alone at greater, but not maximal, doses. We compared the concomitant use of benazepril, 5 mg, and losartan, 25 mg, and monotherapy with these agents in doses 2-fold greater. METHODS: This is a randomized, open, crossover study of 3 treatments in 3 periods of 4 months each. Twenty-four patients with primary glomerulonephritis and nonnephrotic proteinuria, recognized previously as not able to be administered high doses of drugs from these classes, completed the protocol. RESULTS: Combined therapy decreased 24-hour proteinuria (-45.54% versus baseline) more effectively than either losartan (-28.17%; analysis of variance, P < 0.01) or benazepril (-20.19%; analysis of variance, P < 0.001) alone. Subgroup analysis showed that antiproteinuric effects of combination therapy, as well as losartan or benazepril alone, were significantly greater in patients with basal proteinuria greater than 2 g/24 h than in those with proteinuria less than this value (P < 0.001, P < 0.01, and P < 0.05, respectively). All therapies significantly decreased blood pressure (BP) compared with baseline, but there were no differences between treatments in BP changes. CONCLUSION: The study shows that combination therapy with very small doses of losartan and benazepril was more effective in reducing proteinuria than greater doses of either agent in monotherapy, and this greater antiproteinuric efficacy was independent of changes in BP.

Adult↗
PubMed1996

Increased sensitivity to bradykinin among African Americans.

BACKGROUND: Angioedema is a potentially life-threatening side effect of angiotensin-converting enzyme (ACE) inhibitors. Although the mechanism of angioedema is not certain, bradykinin has been implicated in its pathogenesis. Compared with Caucasians, African Americans are at an increased risk of ACE inhibitor-associated angioedema, independent of ACE inhibitor dose or concurrent medications. Because urinary kallikrein levels are decreased in African Americans with hypertension, we hypothesized that endogenous bradykinin levels may be decreased in African Americans and that they therefore may be more sensitive to ACE inhibitor-induced increases in bradykinin or to exogenous bradykinin. OBJECTIVE: To test this hypothesis, we measured the wheal response to intradermal injection of bradykinin in salt-replete hypertensive and normotensive African Americans and Caucasians. METHODS: Two doses of bradykinin, 1 microgram and 10 micrograms, were administered on separate days in a randomized, double-blind fashion. RESULTS: Higher bradykinin dose (analysis of variance: F = 38.33, p < 0.001), African American race (analysis of variance: F = 17.90, p < 0.001), and hypertension (analysis of variance: F = 4.37, p = 0.05) were all associated with an increased wheal response to bradykinin. CONCLUSION: These data provide additional support for racial differences in the kallikrein-kinin system and also implicate abnormalities of the tissue kallikrein-kinin system in essential hypertension.

Adolescent↗
PubMed1979

Testing twin means and estimating genetic variance: basic methodology for the analysis of quantitative twin data.

Twin methodology for the analysis of continuously distributed traits is presented as a guideline for initial steps in the analysis of twin data. Tests for heterogeneity of twin means and variances are reviewed along with estimates of genetic variance. Analysis of twin data appears on the surface to be a rather simple task, but investigators may well be confused by the wealth of choices available for hypothesis testing. This paper is designed to help the less experienced investigator, with perhaps a modest amount of data, begin analysis with maximum attention to testing all testable assumptions of the twin model, and using recent examples of applications of the methods.

Female↗