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At least 1,729 records · Page 96Linked to original sources
PubMed2003

Role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery in triplet pregnancies with therapeutic cerclage.

OBJECTIVE: To assess the role of transvaginal sonographic cervical length in predicting spontaneous preterm delivery at < 32 weeks in patients with both triplet pregnancy and therapeutic cerclage. STUDY DESIGN: The maternal records of all triplet pregnancies with therapeutic cerclage and sonographic cervical length before and after cerclage were reviewed (n = 17). Each of these triplet gestations was matched with 2 triplet pregnancies without cerclage based on cervical length after cerclage (+/- 0.5 cm) and gestational age (+/- 3 weeks). Statistical analysis included Fisher's exact test or chi 2 analysis, one-way analysis of variance, logistic regression analysis and receiver operating characteristic curve analysis. RESULTS: Cerclage was placed at a gestational age of 19.0 +/- 3.1 weeks (mean +/- SD) and increased cervical length from 2.0 +/- 0.7 cm to 3.1 +/- 1.4 cm (P < .05). The rate of spontaneous preterm delivery at < 32 weeks was higher among cases than controls (7/17 vs. 4/27, P = .08). Logistic regression analysis demonstrated that only postcerclage cervical length was predictive of spontaneous preterm delivery at < 32 weeks, with a cervical length of 3.3 cm the optimal predictor. CONCLUSION: In women with triplets and therapeutic cerclage, the only significant predictor of spontaneous preterm delivery at < 32 weeks is cervical length after cerclage placement.

Adult↗
PubMed2003

[Value of endovaginal ultrasound to explain voiding disorders after TVT (Tension-free Vaginal Tape)].

OBJECTIVE: To assess the role of endovaginal ultrasound to explain voiding disorders observed after TVT (Tension-free Vaginal Tape). MATERIALS AND METHODS: Fifty one patients were investigated by an endovaginal ultrasound 3 months after TVT to measure the length of the tape and its distance from the bladder neck. In parallel, cure (group 1), the presence of voiding disorders such as dysuria (group 2) and the presence of urge incontinence (group 3) were evaluated by self-administered questionnaire and clinical examination. Statistical analysis was based on analysis of variance (ANOVA). RESULTS: Analysis of measurements of the TVT-bladder neck distance showed a significant difference between groups 1 and 2: 13.2 vs 7.6 mm, and between groups 1 and 3: 13.2 vs 18.5 mm. Similarly, a significant difference was observed for the TVT length between groups 1 and 2: 8.8 vs 6.6 mm, but not between groups 1 and 3. Analysis of TVT-bladder neck distance in groups 2 and 3 revealed a significant difference: 7.6 vs 18.5 mm, but the length of the TVT was not significantly different between these 2 groups. CONCLUSION: These results demonstrate a correlation between the various voiding disorders observed after TVT and endovaginal ultrasound measurement of the distance between the TVT and the bladder neck.

Adult↗
PubMed2005

[A study of frictional resistance of archwires and ligating methods].

PURPOSE: To study the effect of 4 archwires and 2 ligating methods on the frictional resistance. METHODS: The static and dynamic friction of different combinations of 4 archwires and 6 preadjusted brackets and 2 ligating methods in the buccal segments were tested in the dry state. The friction was tested by the load cell in the LJ-500 testing machine. Orthogonal experiment design was performed in this study. The data were analysed by analysis of variance and regression analysis using the statistical analysis system. RESULTS: The smallest frictional resistance in 4 different archwires was produced by combination of 0.018 x 0.025 inch stainless rectangular wire and all preadjusted brackets. The biggest frictional resistance in 4 different archwires was produced by combination of 0.019 x 0.025 inch stainless rectangular wire and all preadjusted brackets. The static friction of combination of 0.020 inch stainless round wire and all preadjusted brackets were higher than 0.018 inch stainless round wire. The dynamic friction of combination of 0.018 inch stainless round wire and all preadjusted brackets were higher than 0.020 inch stainless round wire. Among 4 kinds of stainless wires, the ratio of dynamic to static friction of 0.018 inch round wire appeared the highest, followed by 0.018 x 0.025 inch rectangular wire, 0.020 inch round wire and 0.019 x 0.025 inch rectangular wire. Elastomeric ring ligature produced higher friction and the ratio of dynamic to static friction than stainless steel ligature. CONCLUSIONS: 0.018 inch stainless steel round wire was not suitable for sliding mechanics in this study. One should pay attention to anchorage control in using 0.019 x 0.025 inch rectangular wire. Elastomeric ring ligature was not advantageous for sliding of brackets and wires in the dry state.

Dental Stress Analysis↗
PubMed2005

[Analysis on the variance of vacA genotypes and their vacuolating toxin activity of Helicobacter pylori isolates in Zhejiang area].

OBJECTIVE: To analyze the variance of vacA genotypes and their vacuolating toxin activity of Helicobacter pylori (H. pylori) isolates from patients with peptic ulcer (PU) or chronic gastritis (CG) in Zhejiang area. METHODS: Signal and middle regions of parts of seventy H. pylori strains were sequenced after T-A cloning. Vacuolating toxin activity was detected with cell culture method. RESULTS: Compared with the reported sequences of H. pylori strain 60190 with s1a/m1 genotype, similarities of the signal-region sequences from 6 s1a-type H. pylori isolates were found to be 93.2%-98.3%, and from 1 m1b-type strain was 87.3%. When compared with the corresponding sequences of H. pylori strain 87-203 with m2 genotype, similarities of the mid-region from 4 m2-type isolates and 1 m1b-type isolates were 93.8%-97.6% and 71.7%, respectively. All 5 strains with s1a/m1 type produced vacuolating toxin activity detected by HeLa, RK-13, and SGC-7901 cell lines. Only 12 strains with s1a/m2 type produced cytotoxin in HeLa cells but 65.1% (28/43) and 62.8% (27/43) strains had cytotoxin in RK-13 and SGC-7901 cells. In RK-13 cells, 81.0% (17/21) strains with s1a/m1b produced vacuolating toxin activity. CONCLUSION: Variance of vacA genotypes of local H. pylori isolates mainly lied in mid-region. H. pylori isolates with m2 type produced high cytotoxin in RK-13 and SGC-7901 cells, and low cytotoxin in HeLa cells. Cytotoxin strength of m1b-type strains was between strains with ml and m2 types. Vacuolating toxin activity of strains from PU group seemed obviously higher than that from CG group.

Animals↗
PubMed1989

Personality characteristics of adolescent marijuana users.

A group of high school students from middle- to upper-middle-class backgrounds was studied to investigate the relationship between marijuana use, marijuana misuse, and personality. The California Personality Inventory and a version of the Adolescent Alcohol Involvement Scale (adapted for the assessment of marijuana involvement) were the primary instruments used. Analysis of variance and regression analysis were performed on the data. Results indicated a relationship between the personality characteristics of adolescents who are involved in marijuana use and misuse and adolescents who are not; there are discernible differences in the personalities of the adolescents who are involved with marijuana. The intervention and prevention implications of these results are discussed.

Achievement↗
PubMed1988

Applications of multivariate analysis in diagnostic cytology.

Three multivariate methods for structure simplification (cluster analysis, principal component analysis and factor analysis) and three multivariate methods for prediction (discriminant analysis, analysis of variance and regression analysis) are discussed and contrasted, along with basic descriptive statistics for multivariate data. These methods are only a subset of the multivariate methods currently in use, but include those that have thus far been applied in diagnostic cytology. Multivariate analyses provide a basis for describing and analyzing large complex data sets and, with the enormous amounts of data becoming available, their applications in many areas of diagnostic cytology must surely increase.

Cytological Techniques↗
PubMed1983

Effects of chronic low level lead exposure on the physiology of individually identifiable neurons.

Although chronic exposure to lead has been correlated with a variety of behavioral and neurochemical deficits in humans and other mammals, little is known of the mechanisms of action of chronic lead at the level of the individual nerve cell. We have used the individually identifiable neurons of the freshwater pond snail Lymnaea stagnalis as a model system to investigate the effects of chronic low level (5 microM) lead exposure on neuronal physiology. Thirteen neuronal parameters were measured with intracellular microelectrode recording in each of six different identifiable neurons or homogeneous neuron clusters. Results were analyzed by a multivariate analysis of variance (MANOVA). MANOVA analysis indicates that there is a significant overall effect of lead exposure (p = 0.0001) and a significant interaction between lead and neuron type (p = 0.01). In most neuron types, chronic lead causes an increase in the resting potential, a slowing of recovery of the membrane potential after the undershoot of a spike, a decrease in spontaneous spiking activity, and a decrease in the input resistance. Lead also has differential effects on identifiable neurons, depressing excitability in some neuron types while not altering excitability in others.

Action Potentials↗
PubMed1981

The association of semen factors with the recovery of Ureaplasma urealyticum.

Ninety-six semen samples from males under examination for suspected subfertility were examined to determine if alterations in specific semen parameters could be associated with the presence or absence of Ureaplasma urealyticum. Forty-three (44.8%) of the specimens cultured positive for U. urealyticum. Both positive and negative specimens have a normal average motility rating. Sperm counts (millions per milliliter) were slightly higher in U. urealyticum positive samples. Average ejaculate volumes were identical between the two groups. Morphologic abnormalities were not found more frequently in U. urealyticum-positive samples. No statistically significant difference between seminal parameters of positive and negative samples were noted with the one-way analysis of variance test. Nonparametric analysis produced similar nonsignificant results.

Humans↗
PubMed1994

[A clinical analysis on the variance of bone density in patients with cirrhosis].

In 46 patients with decompensated posthepatitis cirrhosis, various clinical manifestations resulted from changes of bone density were noted. The relation between the changes of bone density and the level of blood calcium, blood phosphorus and alkaline phosphatase (AKP) as well as the metabolism of vitamin D was studied. It is shown that: (1) Bone mineral content (BMC) in the cirrhosis group decreased as compared with that in a control group (P < 0.05). (2) Blood calcium and phosphorus level decreased, whereas AKP level increased significantly (P < 0.01) in the cirrhosis group. (3) When BMC decreased, blood calcium and phosphorus level also decreased significantly (P < 0.01). When the condition of cirrhosis deteriorated, these changes became more obvious. The reasons may be: (1) Disorder of vitamin D metabolism in cirrhosis. (2) Decrease of calcium absorption by intestine. (3) Nutritional disturbance. It is suggested that the occurrence of bone rarefaction in cirrhosis was due to multiple factors.

Adult↗
PubMed1993

Myopia and myopic progression among schoolchildren: a three-year follow-up study.

PURPOSE: To discuss the factors that might explain the rate of myopic progression and the degree of myopia after a 3-year follow-up among schoolchildren with myopia. METHODS: Myopic progression among 238 schoolchildren was followed up in a randomized clinical trial of myopia treatment. The associations between the explanatory factors and myopic progression and the final value of the spherical equivalent after the follow-up were studied by analysis of variance and regression analysis. RESULTS: Myopia progressed faster among girls than boys. According to the regression models for the boys, 25% of the variation of myopic progression and 57% of the final spherical equivalent could be explained by initial spherical equivalent, age at receiving first spectacles, time spent on sports and outdoor activities, and on reading and close work. Among the girls, 30% of myopic progression could be explained by age at receiving first spectacles, time spent on reading and close work, and reading distance. Similarly, 49% of the final spherical equivalent could be explained by age at receiving first spectacles, initial spherical equivalent, time spent on reading and close work, and reading distance. The rest of the variations could not be explained by the variables measured in this study. CONCLUSIONS: The factors with the most significant relationships to myopic progression were sex, age of onset, and degree of myopia at the beginning of the follow-up. Myopic progression and final myopia were related to time spent on reading and close work and to reading distance but not, however, to accommodation stimulus.

Accommodation, Ocular↗
PubMed1993

Validity of the Family APGAR in patients with irritable bowel syndrome.

BACKGROUND: This study explores the validity of the Family APGAR (adaptability, partnership, growth, affection, and resolve), a test of family function, in persons with irritable bowel syndrome (IBS). Previous studies have reported increased stress in persons with IBS in the form of marital and interpersonal relationships. METHODS: The Family APGAR and the MMPI were completed by 198 persons, including 58 who sought care for IBS, 67 with IBS who did not seek care, and 73 who did not have the disorder. Family APGAR scores were compared for the three groups using analysis of variance. Multiple regression analysis was used to compare Family APGAR scores with both IBS group status and MMPI K and L scales. An odds ratio was calculated for the two groups with IBS. RESULTS: Mean Family APGAR scores were in the normal range for all three groups and differed by less than 1 point among the groups. The Family APGAR score did not differentiate among persons with IBS but was strongly related to the MMPI K score, a measure of defensiveness in test taking. CONCLUSIONS: The failure of the Family APGAR to detect the family dysfunction found by psychological interviewing and the strong relationship with the MMPI K scale lead us to question the construct validity of the APGAR. More sophisticated test construction is necessary to measure family dysfunction in patients who may tend to respond defensively.

Adult↗
PubMedDate not supplied

Proton MR spectroscopy of squamous cell carcinoma of the extracranial head and neck: in vitro and in vivo studies.

PURPOSE: To determine the ability of in vitro one-dimensional and two-dimensional proton MR spectroscopy to help differentiate squamous cell carcinoma of the extracranial head and neck from normal tissues and to correlate the in vitro observations with clinical studies. METHODS: In vitro 1-D and 2-D correlated proton MR spectroscopy (11 T) was performed in tissue specimens of squamous cell carcinoma of the head and neck (n = 19), in normal tissue (n = 13), in metastatic cervical lymph nodes (n = 3), and in a squamous cell carcinoma cell line. In vivo 1-D proton MR spectroscopy (1.5 T) was performed in patients with squamous cell carcinoma (n = 7) and in healthy volunteers (n = 7). The ratio of the areas under the choline (Cho) and creatine (Cr) resonances were calculated for 1-D proton MR spectra for the in vitro tissue studies and correlated with the in vivo studies. Data from in vitro 2-D correlated spectroscopy were analyzed for differences in the presence or absence of various metabolites in samples of tumor and normal tissue. Statistical analysis consisted of 2 x 2 factorial repeated measures analysis of variance (ANOVA), discriminate analysis, and chi2 test. RESULTS: The mean in vitro 1-D proton MR spectroscopic Cho/Cr ratio was significantly higher in tumor than in normal tissue. The difference between the mean ratios appeared to increase with increasing echo time. All in vivo tumor Cho/Cr ratios were greater than the calculated mean in vitro tumor ratio, whereas six of the seven volunteers had no detectable Cho and Cr resonances. Two-dimensional correlated MR spectroscopic data revealed that a variety of amino acids have a significantly greater likelihood of being detected in tumor than in normal tissues. CONCLUSIONS: One-dimensional and 2-D proton MR spectroscopy can help differentiate primary squamous cell carcinoma and nodal metastases containing squamous cell carcinoma from normal tissue both in vitro and in vivo. In addition, 2-D spectroscopy can help identify the presence of certain amino acids in squamous cell carcinoma that are not detected in normal tissue.

Carcinoma, Squamous Cell↗
PubMed1998

Adjusting sample size for anticipated dropouts in clinical trials.

Statistical models for calculating sample sizes for controlled clinical trials often fail to take into account the negative impact that dropouts have on the power of intent-to-treat analyses. Empirically defined dropout correction coefficients are proposed to adjust sample sizes for endpoint analysis of variance (ANOVA) and analysis of covariance (ANCOVA) that have been initially calculated assuming complete data. The implications of type of analysis (change-score ANOVA or ANCOVA), correlational structure of the repeated measurements (compound symmetry or autoregressive), and percentage of dropouts (20% or 30%) are considered, together with other less influential design and data parameters. We recommend the use of ANCOVA to correct for baseline differences and for time-in-study if there is a nonspecific change across time. Given a realistic autoregressive (order 1) correlational structure for the repeated measurements and a proposed endpoint ANCOVA, the empirical results support the common practice of increasing calculated sample size by the anticipated number of dropouts. The previous rationale has been to retain a requisite number of "completers" on which to base statistical inferences. We believe the present results provide the first documentation of the relevance of that strategy for intent-to-treat analyses in which the incomplete data for dropouts must be included. Based on comparative power analyses, the strategy also seems appropriate for maintaining the power of mixed-model regression analyses, simple regression on a normalized time scale, and analyses of trends fitted to imputed scores for dropouts.

Clinical Trials as Topic↗
PubMed1991

Unraveling the mystique of power analysis.

Power analysis provides one method for assessing the efficacy of alternative research designs. The purpose of this article is to simplify the methods for calculating power analysis to determine an adequate sample size. Although attention to type I errors (alpha error) is prevalent among nurse researchers, there is less appreciation for research problems resulting from a type II error. Without the a priori examination of the power of the test of significance, there is no assurance that the sample is sufficient to discern significant differences. Formulas for calculating effect size are provided for t tests, correlations, chi-square, analysis of variance, and regression. Examples of calculating the effect size by using four different statistical tests based on research studies are presented: t tests with unequal variance between groups, chi-square, an analysis of variance, and regression. Power analysis is an additional procedure to ensure that the sample size is adequate for the research project about to be undertaken.

Nursing Research↗
PubMed1993

Linear body measurements of cattle before and after 20 years of selection for postweaning gain when fed two different diets.

At weaning and again after postweaning gain tests, height and width at hips, height at withers, body length, girth, head length and width, muzzle width, and cannon bone circumference measurements were obtained from Angus and Hereford bulls and heifers born in 1964, 1984, and 1985 (n = 989). The cattle were from the initial and final two calf crops selected for postweaning gain when fed either a high-concentrate diet or an all-hay diet. Analysis of variance and canonical discriminant analysis were used to examine the relationships among body measurements and major sources of variation (breed, year of birth, sire within breed and year, diet, sex of calf, age of dam, and the regression on age of calf). Canonical discriminant analysis indicated that one underlying variate explained nearly 90% of the total variation among the weaning measurements, whereas three variates were required to account for that proportion in the end-of-test measurements. At both measurement times, the first canonical variate was associated with year of birth, the second with sex of calf, and the third with dietary energy. Correlations between each canonical variate and the original body measurements indicated that year of birth (variate 1) was most closely associated with body length and cannon bone circumference at weaning and with body length and height at hips (but not withers) at end of test. Sex of calf (variate 2) was associated most closely with width of muzzle and head. Diet (variate 3) was associated with heart girth. Faster-growing cattle were longer in body, but not necessarily taller.

Analysis of Variance↗
PubMed1995

Tests that are robust against variance heterogeneity in k x 2 designs with unequal cell frequencies.

Heterogeneity of variance produces serious bias in conventional analysis of variance tests of significance when cell frequencies are unequal. Welch in 1938 and 1947 proposed an adjusted t test for the difference between two means when cell frequencies and population variances are both unequal. This article describes two ways to use the Welch t to evaluate the significance of the main effect for two treatments across k levels of a concomitant factor in a two-way design. Monte Carlo results document the bias in conventional analysis of variance tests and the stable and appropriately conservative results from applications of the Welch t to evaluation of treatment effects in the two-way design.

Analysis of Variance↗
PubMed1997

Relationship between static chemical and cyclic mechanical fatigue in a feldspathic porcelain.

OBJECTIVES: The goal of this study was to determine if static chemical and cyclic mechanical fatigue are independent, or if they interact to produce greater than additive strength loss in a feldspathic porcelain. METHODS: A blunt indentation technique was used to investigate the response of a feldspathic dental porcelain to cyclic mechanical fatigue and static chemical fatigue. All specimens were fabricated in a dry inert environment and then mechanically fatigued by cyclic loading and strength-tested in dry inert nitrogenous, ambient or wet environments. A series of experiments were performed to evaluate the effects of chemical and mechanical fatigue, and their interaction on strength loss; to determine the effects of, and interaction between, the factors of cyclic fatigue environment and strength test environment on strength; to ascertain if the type of environment during strength testing influenced specimen strength; and to distinguish between chemical damage caused by exposure to moisture alone and stress corrosion damage resulting from the strength testing environment, using a pair of two-way analysis of variance, a single one-way analysis of variance and a t-test (p < 0.05). RESULTS: These experiments indicated that both static chemical fatigue and cyclic mechanical fatigue significantly reduced specimen strength, but they did not interact to produce greater than summative effects. It was also learned that chemical fatigue was not detected on initial exposure to moisture and that it occurred to a small extent during mechanical fatigue cycling, and primarily occurred during strength testing through a stress-corrosion phenomenon. Micrographs visually evaluated the effects of mechanical and chemical fatigue on surface contact damage. SIGNIFICANCE: As both static chemical and cyclic mechanical fatigue influenced porcelain strength, they should both be considered in future evaluations. However, because they largely acted independently, they can be studied separately.

Aluminum Silicates↗