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PubMed1985

Cephalometric comparisons of the dentofacial relationships of two adolescent populations from Iowa and northern Mexico.

The purpose of this study is to develop cephalometric standards for North Mexican male and female adolescents. The subjects evaluated in the study included 36 North Mexican boys with a mean age of 12.8 years and 45 North Mexican girls with a mean age of 13.0 years. The Iowa sample included 20 boys and 15 girls of similar age who were participants in the longitudinal facial growth study at the University of Iowa. Basic descriptive statistics are presented on 26 cephalometric parameters arranged in five categories: skeletal angular relationships, skeletal linear relationships, dental angular relationships, dental linear relationships, and soft-tissue profile relationships. The general linear models procedure--analysis of variance--was used for comparisons between the two populations. F values were calculated for the overall group comparisons and indicated the presence of statistically significant differences between the four subgroups examined, namely, Iowa boys and girls and North Mexican boys and girls. Significant differences between boys and girls within each population were found in the skeletal linear parameters of both the anterior and posterior face heights. Furthermore, in the North Mexican population, the Holdaway soft-tissue angle was significantly larger in boys than in girls, indicating a more convex soft-tissue profile for boys at this age. When comparisons were made between the two populations, it was of interest to note the absence of any significant differences between the North Mexican and Iowa boys. But when the North Mexican girls were compared to the Iowa girls, the SNB and SNPog angles, as well as the ratio of posterior face heights, were significantly larger for the North Mexican girls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

Qualitative comparison of the bilayer-associated structures of diacylglycerol and a fluorinated analog based upon oriented sample NMR data.

sn-1,2-Dimyristoylglycerol (DMDAG) and sn-1,2-dimyristoyl-3-fluoropropanediol (DMFPD) were synthesized in carbonyl 13C-labeled and acyl chain perdeuterated forms. These compounds were reconstituted at low levels into both randomly dispersed dimyristoylphosphatidylcholine (DMPC) bilayers and magnetically orientable DMPC media. Samples were subjected to NMR analysis, leading to a substantial body of 2H quadrupolar splitting, 13C-13C and 13C-19F dipolar coupling and 13C chemical shift anisotropy data for both compounds. A number of measurements were also made for DMPC. The data acquired from magnetically oriented samples were found to be undesirably affected by the presence of artifacts related to the experimental use of the oriented lipid media. However, it was possible to draw a number of qualitative conclusions from the data and to correct the data so that they may ultimately prove useful in quantitative structural analyses of bilayer-associated DMDAG and DMFPD. Comparison of the DMDAG data with corresponding measurements of DMPC suggests a high degree of similarity between the two compounds within bilayers composed primarily of L alpha phase phosphatidylcholine, consistent with previous work (S.O. Smith et al. (1992) Biochemistry 31, 11660-11664). Comparison of the data for DMDAG and DMFPD suggests that the hydroxyl proton of DMDAG is involved in hydrogen bonding interactions, which appear to be largely responsible for maintaining the orientational inequivalence of its two acyl chains. Bilayer-associated DMFPD also appears to exhibit a higher degree of whole-molecule disorder than DMDAG, again suggestive of an important structural role for the hydroxyl proton of DMDAG. Finally, comparison of 13C-NMR data for oriented DMPC in the presence and absence of low levels of DMDAG and DMFPD indicated that neither compound induces a significant change in the averaged conformational state of DMPC comprising the bilayer matrix of the oriented samples.

Carbon Isotopes↗
PubMed1989

Hemodynamics in transposition of the great arteries with comparison to ventricular septal defect.

This paper uses a mathematical model of the circulations to study the hemodynamics of transposition of the great arteries (TGA) with comparison to ventricular septal defect (VSD). Computer experiments are conducted to determine the influence of the defect conductance and the pulmonary vascular conductance on the pulsatile pressures, flows, and oxygen concentrations of the circulation. In particular, the model is used to determine the waveform of the (possibly bidirectional) shunt through the ventricular and atrial septal defects. The results of the computer experiments consist of two parts. The first set of experiments is devoted to the comparison of VSD and TGA with a ventricular septal defect. The results are theoretical in the sense that most parameters have been fixed at the same levels. In each case TGA is represented by changing the connection of the chambers and reversing the compliance of the two ventricles. In the second set of experiments we attempt to simulate conditions clinically observed in a variety of cases of TGA. In each case we use clinical observations to infer parameters as the input to the model. We find that the model (with appropriate choice of parameters) generally exhibits blood pressure, blood flows and oxygen concentrations similar to the clinical observations. As a byproduct of these computer experiments we predict the effects of changing the pulmonary conductance. The comparison between TGA and VSD shows that as the defect conductance increases, the systemic oxygen concentrations decrease in VSD and increase in TGA. Even at large defect conductance, the two conditions remain distinct, however, since the mixing of the right and left ventricular blood pools is incomplete. This phenomenon of incomplete mixing sets quantitative limits on the benefits that can be achieved by surgical enlargement of the defect. A result of this study that may be useful in the management of TGA patients with a ventricular septal defect is the finding that there is a value of the pulmonary conductance that maximizes the effective flow and hence the systemic oxygen concentrations. The optimal pulmonary conductance is approximately equal to the systemic conductance when the defect is large.

Computer Simulation↗
PubMed1988

Bedside serial comparison of electrocardiograms.

A unique method for serial comparison of electrocardiograms is introduced. A Siemens 440 or 740 electrocardiograph can be linked directly to a central minicomputer system, from which serial data for up to three previously recorded ECGs from the same patient can be retrieved and transferred back to the ECG machine. Serial comparison logic has been incorporated into the diagnostic program inside the 440 and 740 so that immediate serial comparison can be undertaken at the bedside or in the clinic.

Computers↗
PubMed1995

Comparison of five calculation modes for antibody ELISA procedures using pertussis serology as a model.

During a phase III pertussis vaccine trial, serum antibody responses were measured by two enzyme-linked immunosorbent assays (ELISA) for pertussis toxin and filamentous haemagglutinin. These were used both for studies of antibody levels after vaccination and for diagnostic purposes. Since the absorbance values obtained were not directly proportional to the amount of antibody in the samples, ELISA optical densities were transformed to units by calibration to a reference serum. Five different calculation modes were compared. In four of these modes unit calculations were based on the relationship between dose response curves of the serum sample and a reference serum. In addition, traditional endpoint titres were included in the comparison. The calculation mode using reference line units showed the highest reproducibility, with intrassay coefficients of variation (CV) within the same test plate of 4-7% and interassay CVs of 12-14%. The CVs among the other methods ranged from 6 to 31% for intra-assay comparisons and from 12 to 47% for interassay comparisons. Furthermore, the CV values for intra-assay variations were used to calculate standardized differences between 79 pairs of acute and convalescent sera from cases confirmed by culture. These differences were then used to estimate the 'diagnostic sensitivity' for the different calculation modes. The results indicated that use of the reference line units was the most sensitive, whereas use of the end point titers was the least sensitive of these calculation modes.

Adult↗
PubMed1981

A comparison of three techniques for fabricating metal molds.

Investigation on the dimensional accuracy and techniques variability of metal molds and refractory casts for the construction of maxillofacial external prostheses have resulted in the following conclusions. 1. A relative comparison of the box-pour, open-cast, and wax-sprue techniques for constructing metal molds for external prostheses showed the open-cast technique to be the most accurate and easiest techniques. 2. The wax-sprue technique was the most complex and consumed maximum time and materials. This technique also offered the greatest possibility for introducing errors and obtaining inconsistent results because of multiple steps. 3. For all techniques the positive metal molds always demonstrated a poorer fit in comparison to the negative metal molds. The positive metal molds were larger castings. 4. Most metal molds were significantly larger than the standard brass die in length and width dimensions. 5. A direct comparison of a theoretic calculation and experimental measurements for dimensional accuracy shows the construction of metal molds to be very dependent on the manipulation of materials and reproducibility of methods.

Dental Casting Investment↗
PubMed1994

Glucose absorption and production following oral glucose: comparison of compartmental and arteriovenous-difference methods.

Both whole-body models and the regional arteriovenous (AV)-difference method have been used to calculate systemic glucose rates of appearance (Ras) under non-steady-state conditions. Although whole-body models have been experimentally validated in the dog, direct comparison of the whole-body and regional-balance approach has not been made in man. We reanalyzed published data obtained by combining the double-tracer technique ([3H]glucose infusion with ingestion of a [14C]glucose-labeled load) with hepatic vein catheterization. Steele's monocompartmental model underestimated the Ra of oral glucose ([RaO] by 12%, P < .0001) and overestimated the Ra of endogenous glucose ([RaE] by 19%, P < .0001) in comparison to a two-compartment (2-c) model calculation. Splanchnic balance data were used to compute the total glucose Ra (RaT) with either steady-state or non-steady-state equations (the latter by estimating splanchnic transit times). Except for one early time point (15 minutes), the two calculations agreed well with one another. The glucose RaT by the balance method was well correlated with that calculated by the 2-c whole-body model (r = .72, P < .0001 on all data points); however, the former significantly underestimated the latter by 0.62 mg.min-1.kg-1 (or 13%, P < .01) on average throughout the absorptive period. This bias was small in comparison to the estimated random error affecting the calculation of glucose RaT by the model, which averaged 1.4 mg.min-1.kg-1 (corresponding to a variation coefficient of approximately 30%).(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Oral↗
PubMed1983

Purity discrimination: successive vs simultaneous comparison method.

Purity discrimination thresholds (delta p) were measured with successive (SOA = 3 sec) and simultaneous (SOA = 0 sec) comparison methods for seven dominant wavelengths; 410, 480, 500, 530, 570, 600 and 650 nm. The stimulus duration was 1 sec. The delta p values with the successive comparison method were found to be about 1.5-2.0 times larger than those obtained in the simultaneous case. The degree of purity discrimination deterioration shown in this study is similar to that of wavelength discrimination deterioration previously reported (Uchikawa and Ikeda, 1981, Vision Res. 21, 591-595). Saturation shifts of stimuli with the successive comparison method were also observed; these were toward increased saturation direction for most dominant wavelengths.

Adult↗
PubMed1990

Prosthetic heart valves: waveform comparisons and average value disposition for pulsatile flow in vitro.

With the development of the in vitro testing of heart valves, the standardization of the test methods becomes increasingly important and they should also be improved continuously. This paper discusses the problems of waveform comparison and average value dispositions. In the pulsatile model driven by pneumatics, the pressures before and after the valve, and the flow through it, are measured as three one-dimensional variates. The mean values are calculated according to the FDA and the ISO. A comparison and analysis of experimental waveforms indicate that, for basically the same ranges of pressures and flow rate, the flow curves of different types of valve are clearly different. The mean values and the waveforms in the time domain should be taken into consideration synthetically so that the pusatile characteristics of the valve can be more completely reflected. Using numerical filtering methods to treat the waveforms allows for better comparisons between the measured results taken from the different devices. By means of the constellation graphical method for treating mean values as multivariates, it is feasible to classify the valves and to judge their qualities under conditions of pulsatile flow.

Computer Graphics↗
PubMedDate not supplied

A new comparison group for research on child sexual abuse.

This paper discusses a new type of comparison group for research on adult survivors of child sexual abuse (CSA). A No Sexual Trauma Comparison Group excludes women who have experienced, during adulthood, a sexual trauma similar in impact to CSA. Using this type of comparison group increases sensitivity to (i.e., the likelihood of detecting) clinically relevant characteristics of CSA survivors.

Adolescent↗
PubMed1990

Sources of discrepancy in the comparison of a lay-administered diagnostic instrument with clinical diagnosis.

This article presents a comparison of the diagnostic results from a lay-administered diagnostic interview for depression with a clinical diagnosis in a community sample. The purpose of the comparison is to assess reasons for the discrepancies between the two diagnostic approaches. The majority of the discrepancies result from inconsistent episode reports at the two interviews. We propose a number of possible explanations for the inconsistencies. An empirical analysis that identifies predictors of consistent vs. inconsistent reports supports a strong influence for respondent recall error. We discuss the implications of our analysis for previous comparisons of lay-administered and clinical diagnostic instruments.

Adult↗
PubMed1992

Comparison of DNA and karyotype ploidy in malignant mesothelioma.

The correlation between flow cytometric analysis and classical karyotyping was examined in malignant mesothelioma. Flow cytometry was used to determine the DNA ploidy mainly from paraffin blocks of 31 mesotheliomas, of which the S-phase fraction (SPF) could be defined in 17 tumors. Chromosomal results were available from 27 of these tumors. For the comparisons, both the modal (the most common) and the mean (the average) chromosome numbers were determined. A significant correlation was observed between ploidy pattern, i.e., DNA indexes and modal as well as mean chromosome numbers (p = 0.004 and p = 0.006, respectively). Otherwise the comparison between the mean chromosome numbers and DNA index proved more relevant. Although the majority of the tumors (16 of 27) had a normal modal chromosome number of 46, only 5 tumors had a normal mean chromosome number, and the remaining 22 had an abnormal number, reflecting the divergent chromosomal abnormalities. Furthermore, comparison of SPF with mean chromosome numbers disclosed a parabolic relationship; i.e., when mean chromosome number corresponded to diploid, near-diploid, or near-tetraploid cell, SPF was low, but SPF was at the maximum when mean chromosome number ranged between 60 and 63. Because SPF is an indicator of cell proliferation, this might suggest that the number of chromosomes as such also corresponds with the growth characteristics of malignant mesothelioma.

Adult↗
PubMed1993

Comparison of treatment techniques for lung cancer.

A comparison of the treatment techniques for a typical case of lung cancer has been performed between 10 Swiss radiation oncology centers. The description and basic imaging data of a locally advanced non-metastatic lung cancer were sent to each institution and participants were asked to perform the treatment planning as for a routine case. The comparison shows that, in addition to a broad spectrum of treatment techniques, there was a significant variation in the major treatment parameters: definition of the target volume, prescription procedure, total dose to the tumor and dose per fraction. Although some reasons could be found to partially explain these differences, the lessons learned from this comparison are, first, that a standardization, in particular for dose prescription, is urgently needed, and, second, that a search for a better consensus in standard managements should be promoted in radiation oncology.

Carcinoma, Non-Small-Cell Lung↗
PubMed1995

Subject-based P1 latency inter-root comparison, a method to evaluate P1 latency in scalp recorded somatosensory evoked potentials obtained with sensory nerve stimulation in the lower extremities.

The purpose of the present study was to establish a method that allows the general use of subject-based criteria to evaluate P1 latency in scalp recorded somatosensory evoked potentials obtained with stimulation of the sural (S1), superficial peroneal (L5) and saphenous (L4) nerves bilaterally. The nerves were stimulated at the same distance from the registration electrode. Two groups of normal nerve roots were studied: (1) nerve roots on both sides in 20 asymptomatic volunteers, and (2) neuroradiologically normal nerve roots on the asymptomatic side in 22 patients with unilateral sciatica. The results presented show that the P1 latencies after stimulation of the 6 different nerves in the same person can be regarded as equal. On this basis 2 criteria to evaluate P1 latency by within-subject P1 latency inter-root comparison were defined. They were the difference between P1 latency of 1 registration and (1) that of any one of the other 5 registrations and (2) the mean P1 latency of the other registrations. The variability of these subject-based criteria and the width of their reference limits were compared to those of the population-based criteria of height- and height-age-corrected P1 latency. This comparison showed that the use of within-subject P1 latency inter-root comparison should enhance the ability to demonstrate small bilateral P1 latency prolongations at the same segmental level.

Adult↗
PubMed1984

Multiple comparison of dried BCG vaccines: stability at 37 degrees C and persistence of strains in the mouse spleen.

The Gabriel test was used for multiple comparison of the stability of vaccines stored at 37 degrees C over a 28 day period and of the long-term relative persistence capacity (RPC) in mice spleen (residual virulence) over a 547 day period following intravenous vaccination with 12 BCG dried products. Multiple comparisons were performed after rejected null hypotheses (Anova, Regranal), with ranked mean viable units 10(6) ml-1 estimates (VU) of vaccines and with ranked mean RPC values in spleen determined with five sampling and on nine autopsy days, respectively. Results showed that VU X 10(6) ml-1 values of the compared vaccines at day 0 varied between 1.1 and 27.0 X 10(6) ml-1 and formed two homogeneous subsets. The heat stability test showed that the VU X 10(6) ml-1 values of the vaccines decreased parallely but at day 28 only six vaccines showed a survival rate over 20%. The RPC model showed that the trends of early multiplication and of late persistence capacity depended on the i.v. BCG VU doses. The Regranal of late RPC indicated that the decrease of BCG VU in mice spleen from 84 to 547 days was parallel and that six strains persisted over 20% at day 360. The overall RPC on the nine autopsy days of the BCG strains was evaluated with Kendall concordance test. In contrast with pairwise comparison, the Gabriel test reduces the risk of type I error in statistical inference at the 5% experimental level and selects the homogeneous subsets of ranked parameter estimates of the compared products.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Restoring acidified streams in upland Wales: a modelling comparison of the chemical and biological effects of liming and reduced sulphate deposition.

Increasing emphasis is being placed on the restoration of surface waters which have been affected by acidification. Amongst the possible strategies are management of the causes, by reducing acidic deposition, and management of the symptoms, by treating affected areas with basic material such as limestone. In few cases have there been comparisons of the likely effect of these two strategies on surface water chemistry and ecology, although there is widespread belief that the two are similar in outcome. At present, only a modelling approach permits such a comparison. This paper describes chemical and biological responses of three Welsh streams whose catchments were limed experimentally in 1987-1988 as part of the Llyn Brianne project. Actual changes are compared with simulated changes which occur following reduced acid deposition according to the hydrochemical model, MAGIC (Model of Acidification of Groundwaters in Catchments). The results indicate that liming and 90% reduction in sulphate deposition reduce concentrations of toxic aluminium to similar levels. However, calcium concentrations and pH were increased by liming to values which were high by comparison with conditions simulated at low acid deposition, either in the past or future. Trout density increased in two of the streams following liming to levels similar to those simulated under low acid deposition. By contrast, the aquatic invertebrate fauna changed after liming so that streams acquired species typical of higher calcium concentrations than those simulated under low acid deposition. Species characteristic of 'soft water' communities were apparently lost, although more data are required to separate treatment effects from random change in the longer term. The 'soft water' community also declined in the model as a result of acidification, indicating that both liming and acid deposition resulted in a different faunal community from that prior to acidification. The results support those who conclude that liming is suitable for the restoration or protection of a fishery, but indicate that there may be other ramifications, for example to conservation, which must be considered when liming is implemented. However, the simulation of biological conditions under low acid deposition involves extrapolation from the initial data base. Further data are now required to assess empirically the likely biological character of British streams which have low base cation concentrations unaffected by acid deposition.

Journal Article↗
PubMedDate not supplied

The validation of duplex scanning and continuous wave Doppler imaging: a comparison with conventional angiography.

Colour-coded continuous wave (CW) Doppler imaging and duplex scanning have been assessed prospectively in comparison with biplanar angiography for their accuracy in detecting significant arterial disease in the extracranial circulation. Of 96 comparisons with biplanar angiography, the sensitivity of Doppler imaging was 90% and specificity 98% in the detection of greater than 50% internal carotid stenosis and 86 and 100%, respectively, in the diagnosis of internal carotid occlusion. Of 85 comparisons with biplanar angiography, the sensitivity of duplex scanning was 93% and specificity 98% in the detection of greater than 50% internal carotid stenosis and 92 and 100%, respectively, in the diagnosis of internal carotid occlusion. The value of the peak systolic Doppler shift frequency of the internal carotid artery signal has proved to be the most reliable indicator of greater than 50% stenosis and is utilised in conjunction with a periorbital examination. It is concluded that both Doppler imaging and duplex scanning are effective screening techniques for the presence of significant (greater than 50%) internal carotid artery disease.

Adolescent↗