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PubMed2003

Testing the validity of comparisons between the rheological and the calorimetric glass transition temperatures.

Dynamic mechanical techniques are used increasingly in the investigation of vitrification phenomena in biological materials, thus posing the question of whether the rheological T(g) should be compared with the established practice of obtaining T(g) values from differential scanning calorimetry. The nature of the rheological T(g) is discussed and its frequency dependence is established with a view to facilitating comparisons with calorimetric data. Despite claims made in the literature, results on high sugar-kappa-carrageenan mixtures, hydrated gelatin films, and thermoset epoxy resins demonstrate that there is no clear reference point for comparison of the glass transition temperatures derived with the two techniques. Furthermore, the structure-forming ability of kappa-carrageenan and other biopolymers impacts primarily upon the mechanical manifestation of vitrification and contributes to the state of complexity of comparisons between thermal and mechanical data.

Calorimetry, Differential Scanning↗

PubMed2000

Comparison of the diagnostic value of cardiac troponin I and T determinations for detecting early myocardial damage and the relationship with histological findings after isoprenaline-induced cardiac injury in rats.

Cardiac troponins I (cTnI) and T (cTnT) have been shown to be highly sensitive and specific markers of myocardial cell injury. The purpose of this study was to investigate the diagnostic value of cTnI and cTnT with regard to creatine kinase (CK) and lactate dehydrogenase (LD) and to determine whether they can be used for early diagnosis of myocardial damage in rats, and to examine the relationship between cTnl and cTnT release with histological examinations, using isoprenaline-induced cardiac muscle damage as an experimental model in the rat. Eighteen Wistar rats per group were treated with a single dose of either isoprenaline (iso) or with normal saline as a control group. The anti-cTnI and cTnT monoclonal antibodies (mAbs) employed in the cTnI (Access) and cTnT (Elecsys) assays cross-react with cTnI and cTnT of the rat. A highly significant rise of cTnl or cTnT was found already 2 h after iso. The time-courses of cTnI and cTnT were monophasic in form. The highest cTnI (mean+/-S.D., 1.1+/-2.3 ng/ml) and cTnT (mean+/-S.D. 3.6+/-30 ng/ml) were found 4 h after iso. cTnI and cTnT significantly increased in iso-treated rats in comparison with controls whether the differences between 2-, 4- and 6-h levels and basal levels were considered or not. The areas under cTnl and cTnT curves (AUC) (0-6 h) and the maximal cTnI and cTnT (0-6 h) after iso were significantly different from the controls. For CK and LD, no elevation in comparison with controls could be detected (except a trend for LD whether or not the difference between 6-h levels and basal levels were considered (P=0.08) and for LD AUC (0-6 h) (P=0. 059)). Correlations between maximal cTnI and cTnT and AUC were 0.69 (P=0.0001) and 0.60 (P=0.0066), respectively. Histological examinations of iso-treated rats revealed acute focal or multifocal myofibrillar degeneration of the myocardial tissue in ten out of 14 rats and showed the earliest alterations 4 h after iso in one treated rat. Only four of the controls exhibited evidence of mild changes and slight mononuclear cell infiltration. cTnl and cTnT peak values to at least 0.35 and 1.3 ng/ml, respectively, were necessary to detect histological myocardial cell injury after iso. cTnI and cTnT were found to be early markers for diagnosing iso-induced myocardial damage in comparison with CK and LD. Elevations of cTnI and cTnT appeared to relate to the severity of histologic changes after myocardial injury. Although there was a difference in the absolute concentration of results between cTnI and cTnT assays, due to a lack of standardization and heterogeneity in the cross-reactivities of mAbs to various troponin I and T forms, cTnI and cTnT can be used as easily measurable target parameters for detection of cardiotoxic and/or cardiodegenerative effects in rats.

Animals↗

PubMedDate not supplied

Comparison of tissue culture and animal models for assessment of Cryptospridium parvum infection.

The current increased interest for using tissue culture as a surrogate for mouse infection to assess Cryptospridium viability suggests that a comparison of the two models is essential for data interpretation. Therefore, a need remains for a statistical comparison that can demonstrate if infection and inactivation predicted by new tissue culture models are comparable with those predicted by animal models. Data from a total of 31 dose-response trials using both tissue culture and mouse models to assess C. parvum infectivity were compared. The dose needed to infect 50% of the tissue cultures (ID(50)) was also compared to each ID(50) in mice. Average ID(50)s developed using the logit dose-response method for tissue culture and mice were 8 and 107, respectively, suggesting that tissue culture was more sensitive to infection. However, correlation (r) between tissue culture and mouse infectivity was statistically significant (0.9167 [95% CI=0.8428 to 0.9594, p<0.0001]). Comparison of oocyst disinfection by UV and chlorine dioxide showed no significant difference between inactivation predicted by tissue culture and mouse models (p=0.8893; t=0.0141; n=21). These results demonstrate that tissue culture can successfully be used to measure C. parvum infection and can be used for determining inactivation in disinfection studies.

Adenocarcinoma↗

PubMed1995

Sperm morphology and in vitro fertilization outcome: a direct comparison of World Health Organization and strict criteria methodologies.

OBJECTIVE: To perform a direct comparison of two sperm morphology methodologies with regard to IVF outcome. DESIGN: Blinded comparison of two methods of morphology assessment using the same morphology slides. PATIENTS: Data were obtained from 132 couples in a consecutive series of patients undergoing IVF. MAIN OUTCOME MEASURES: Two practical end points were selected for analysis for each couple: the presence of any fertilization and the number of fertilized eggs. Normal traditional morphology was defined as > or = 40% normal forms in a sample and normal strict criteria was defined as > or = 4%. RESULTS: Traditional morphology demonstrated a higher sensitivity and negative predictive value than strict criteria (87% versus 61%, and 68% versus 36%, respectively). Positive predictive value and specificity were also numerically greater but did not reach statistical significance. Abnormal traditional morphology, but not strict criteria, was associated with reduced fertilization even among samples with normal sperm concentration and motility. Samples with normal morphology were associated with a greater number of fertilized eggs per couple than those with abnormal morphology: this difference was 3.2 fertilized eggs for traditional morphology and 1.6 for strict criteria. Overall, for samples with < 40% by traditional morphology only one case yielded more than two fertilized eggs. In contrast, up to five fertilized eggs were noted for the lowest strict criteria scores. CONCLUSIONS: Comparison of traditional morphology and strict criteria with regard to IVF outcome favored traditional morphology in several areas. In particular, low scores were more predictive of poor IVF outcome.

Female↗

PubMedDate not supplied

A study of the probative value of Afro-Caribbean hair comparisons.

The interpretation of human hair comparisons is highly subjective and examiners tend to be cautious when evaluating positive evidence, partly because of a lack of background information relating to the interpretation of the results obtained. The purpose of this paper is to share the authors' experience of examining a large number (118) of samples of Afro-Caribbean hair. The strategy employed provided a rapid response, and only 11 (9.3%) individuals could not be excluded on the basis of hair comparison. It was concluded that not only are comparisons of Afro-Caribbean hairs possible but a significant proportion of individuals can be excluded by such tests.

Black People↗

PubMed1998

A comparison of analytic procedures for measurement of fractional dextran clearances.

Fractional dextran clearances have been extensively used to study glomerular size selectivity. We report on an analysis of different laboratory procedures involved in measuring fractional dextran clearances. The deproteinization of plasma samples by 20% trichloroacetic acid (TCA) revealed a protein contamination of 0.2% +/- 0.3%, whereas both 5% TCA and zinc sulfate deproteinization revealed a significantly higher remaining sample protein content (2.5% +/- 0.4% and 3.4% +/- 0.1%, respectively). Only zinc sulfate revealed incomplete deproteinization of urine samples (0.6% +/- 0.2%). Dextran recovery in plasma and urine supernatants was significantly lower after 5% TCA and zinc sulfate deproteinization when compared with 20% TCA deproteinization. Gel permeation chromatography (GPC) and high-performance liquid chromatography (HPLC) showed a variance of calibration smaller than 5% over 1 year. The use of 3 different sets of standard dextrans revealed significant differences in calibration. GPC and HPLC followed by anthrone assay showed a comparable variance in dextran concentration in plasma, from 3 to 6 nm (14% to 25%), whereas the variance in urine was lower for the GPC and anthrone assay, especially from 5.4 to 6 nm (23% to 43% versus 50% to 78%). HPLC and online refractometry showed the lowest variance of dextran concentration in plasma, from 3 to 6 nm (<4%), and in urine, from 3 to 5.2 nm (<7%), whereas it showed a higher variance in urine, from 5.4 to 6 nm, in comparison with GPC and HPLC with the anthrone assay. The GPC and anthrone assay revealed higher fractional dextran clearances in comparison with the HPLC and anthrone assay in healthy subjects (3 to 5.4 nm) as well as in patients with nondiabetic proteinuria (4.2 to 5.8 nm), and lower clearances in patients from 3 to 3.4 nm. The HPLC and anthrone assay revealed higher clearances in comparison with HPLC and online refractometry in healthy subjects (3.6 to 5.4 nm) and in patients (3.6 to 5.2 nm). The GPC and anthrone assay revealed characteristic differences in fractional dextran clearances between healthy subjects and patients. The HPLC and anthrone assay showed no significant differences between both groups, whereas HPLC and online refractometry showed only an increased clearance of dextrans from 4.6 to 5.2 nm in patients. Fractional clearances of dextran 5.6 nm as estimated by all 3 dextran assays were not significantly related to the fractional immunoglobulin G clearance or the immunoglobulin-to-albumin clearance index in our patients. Quantitative and qualitative differences in fractional dextran clearances may be induced by differences in laboratory procedures. We recommend sample preparation by 20% TCA deproteinization, frequent calibration with 1 set of dextran standards with low polydispersity, size-exclusion chromatography by GPC, and dextran detection by anthrone assay for optimal measurement of fractional dextran clearances. Even with such an approach, however, the variability in the measurement remains extremely high in the important range of dextrans greater than 5 nm.

Chromatography, Gel↗

PubMed2003

COMPASS: a tool for comparison of multiple protein alignments with assessment of statistical significance.

We present a novel method for the comparison of multiple protein alignments with assessment of statistical significance (COMPASS). The method derives numerical profiles from alignments, constructs optimal local profile-profile alignments and analytically estimates E-values for the detected similarities. The scoring system and E-value calculation are based on a generalization of the PSI-BLAST approach to profile-sequence comparison, which is adapted for the profile-profile case. Tested along with existing methods for profile-sequence (PSI-BLAST) and profile-profile (prof_sim) comparison, COMPASS shows increased abilities for sensitive and selective detection of remote sequence similarities, as well as improved quality of local alignments. The method allows prediction of relationships between protein families in the PFAM database beyond the range of conventional methods. Two predicted relations with high significance are similarities between various Rossmann-type folds and between various helix-turn-helix-containing families. The potential value of COMPASS for structure/function predictions is illustrated by the detection of an intricate homology between the DNA-binding domain of the CTF/NFI family and the MH1 domain of the Smad family.

Amino Acid Motifs↗

PubMed1989

Outcome after posthemorrhagic ventriculomegaly in comparison with mild hemorrhage without ventriculomegaly.

The neurodevelopmental sequelae in 33 low birth weight neonates with moderate or severe hemorrhage and ventriculomegaly (VM group) and in 39 neonates with mild hemorrhage only (non-VM group) were evaluated prospectively. Both groups were comparable in birth weight, gestational age, and socioeconomic status. Ventriculoperitoneal shunts were inserted in 23 of the 33 VM group infants at a mean age of 26 days. Eighty-two shunt revisions were performed, for obstruction (71 revisions) or infection (11 revisions), in 18 of the 23 children. At a mean age of 50 months, 19 of 33 children in the VM group had sequelae; 14 children had moderate or severe neurologic deficits, and 5 children had mild sequelae. In the non-VM group, only 3 of 39 children had deficits, all of which were mild (p less than 0.05). In the VM group, 19 of 33 children had mental developmental delay in comparison with 8 of 39 in the non-VM group (p less than 0.05), and 17 of 33 children in the VM group had motor developmental delay in comparison with 5 of 39 in the non-VM group (p less than 0.01). Within the VM group, the number of children with neurodevelopmental sequelae did not differ significantly among the 23 children with shunts, in comparison with the 10 who did not require shunting. Among the children with shunts, a higher incidence of sequelae occurred when lack of ventricular decompression was noted immediately after shunt insertion (p less than 0.005) and when shunt infections occurred (p less than 0.01). The most important predictor of mental and motor outcome in the group with shunts was lack of ventricular decompression immediately after shunt insertion. We speculate that, in some infants, loss of brain tissue, cerebral atrophy, or both may occur before insertion of the ventriculoperitoneal shunt, even when the shunt is inserted early.

Cerebral Hemorrhage↗

PubMed1997

Comparison of occlusal contacts in maximum intercuspation for two impression techniques.

STATEMENT OF PROBLEM: At the insertion of a fixed prosthesis, occlusal interferences in maximum intercuspation are often present. PURPOSE: This study investigated and compared the accuracy of interocclusal relationships in maximum intercuspation for mounted casts obtained from a quadrant dual-arch impression technique and conventional full-arch impression techniques. MATERIAL AND METHODS: Comparisons were made between an intraoral interocclusal record and interocclusal records made on mounted casts. Irreversible hydrocolloid, reversible hydrocolloid, polysulfide, polyether, and polyvinyl siloxane were used for the full-arch impression technique. For the quadrant dual-arch impression technique, rigid polyvinyl siloxane and light-body polyvinyl siloxane injection materials were used. RESULTS: Statistical analysis revealed a statistically significant difference (p = 0.0017) in the median values among treatment groups. All pairwise multiple comparison procedures (Student-Newman-Keuls) indicated the average error of the quadrant dual-arch records was significantly different from the average error of each group of records produced with the full-arch techniques (p < 0.05). Comparison of the records of the full-arch impressions did not reveal any statistically significant differences. The average error of the full-arch records was 72 +/- 33 microns and the quadrant dual-arch average error was 5 +/- 5 microns. CONCLUSION: The quadrant dual-arch impression technique produced mounted casts with significantly more accurate maximal intercuspal relationships than mounted casts from full-arch impressions.

Alginates↗

PubMed1987

A structural comparison of type c lysozymes based on their hydropathic profiles.

Hydropathic profiles can be considered as an approach to the three-dimensional structure of a protein and so their use for comparison of homologous proteins is proposed, as they provide information on relative structural conservativeness. A simple approach was developed for comparison of hydropathic profiles and applied to 19 lysozymes c of known primary structure. Trees were constructed in order to discover which method yielded the best estimation of the phenotypic differences between the proteins considered, by means of the goodness-of-fit criterion. Iterative methods, such as the Fitch-and-Margoliash and the unweighted-pair-group methods, gave a better fit than did a non-iterative method. When the hydropathic approach is used for comparison of lysozymes c, the enzyme obtained from chachalaca egg-white is placed closer to those from pheasant-like birds than to those of ducks; this result agrees with the morphological resemblance of the chachalaca to pheasant-like birds. Pigeon egg-white and equine milk lysozymes differ greatly in sequence from other lysozymes c and their hydropathic analysis shows important differences with respect to the other homologous enzymes.

Amino Acid Sequence↗

PubMed1997

Quantitative and qualitative comparison of spontaneous and chemical-induced specific-locus mutation in the ad-3 region of heterokaryon 12 of Neurospora crassa.

The data from forward-mutation experiments to obtain specific-locus mutations at two closely linked loci in the adenine-3 (ad-3) region of heterokaryon 12 (H-12) of Neurospora crassa have been tabulated to determine the relative frequencies and mutational spectra of ad-3 mutants occurring spontaneously and those induced by 22 different chemical treatments. Previous studies have demonstrated that specific-locus mutations at these two loci result from 5 major genotypic classes, namely two classes of gene/point mutations (ad-3AR and ad-3BR), and 3 classes of multilocus deletion mutations ([ad-3A]IR, [ad-3B]IR and [ad-3A ad-3B]IR). In addition, prior studies have demonstrated that some chemical mutagens induced ad-3 mutants exclusively, or almost exclusively, by gene/point mutation and other chemical mutagens by gene/point mutation and multilocus deletion mutation. In the latter cases, there was wide variation in the percentages of ad-3 mutants in these 5 major genotypic classes. Two comparative methods of analysis that also were used to compare spontaneous and chemical-induced ad-3 mutational spectra included X2-tests on the numbers of ad-3 mutants resulting in the following two sets of ratios: (1) gene/point mutations and multilocus deletion mutations; and (2) complementing and non-complementing ad-3BR, mutants. Combination of the p-values from X2-tests for these two methods of comparison demonstrated that all 22 chemicals induce a spectrum of ad-3 mutants that is qualitatively different from that occurring spontaneously. In addition, these same two methods of comparison have been used to compare the mutagenic effects of each of the 22 chemical treatments with each other. Combination of the data from these two methods of comparison has demonstrated that 93.1% (215/231) of the pairwise combinations of these 22 chemicals were different from each other. The implication of these experimental data on the induction of specific-locus mutations in somatic cells of Neurospora for genetic risk assessment exercises is discussed.

Adenine↗

PubMed1999

In vitro production of pig embryos: comparisons of culture media and boars.

The utilization of in vitro produced pig embryos for commercial production or research is dependent upon the development of improved methodology. Our objective was to establish a consistent in vitro embryo production (IVP) system and subsequently utilize the procedures to evaluate culture system components and boar effects. To summarize the IVP system, 403 inseminated oocytes from a total of 2243 were analyzed across 17 replicates for maturation and fertilization efficiency, while 1838 zygotes were cultured in 26 replicates for developmental data. Penetration, cleavage and blastocyst development rates were determined at 18, 44 and either 144 or 168 h post insemination, respectively. Monospermic penetration averaged 31.8+/-7.3% while polyspermy was 30.8+/-17.2%. Cleavage rate was 44.9+/-16.1%, with 21.8+/-7.5% of fertilized oocytes and 51.9+/-15.9% of cleaved embryos developing to blastocysts. For culture medium comparison, fertilized oocytes were cultured in either BECM-6, BECM-7, NCSU-23 or NCSU-23aa and supplemented on Day 5 post insemination (pi) with 10% FCS. These treatments resulted in 4.0, 4.9, 19.8 and 13.6% (+/-3.2%) blastocysts by Day 7 pi, with an average cell number of 44.4+/-9.0, 65.1+/-8.2, 61.3+/-4.5 and 64.4+/-4.8, respectively. These IVP procedures consistently produced zygotes from semen of several different boars, capable of forming blastocysts in vitro. Comparison of developmental rates among the boars indicated that this system is variable among boars but not strictly boar-dependent. Culture media comparisons suggest that NCSU-23 yielded a higher percentage of blastocysts than the other media in this IVP system.

Animals↗

PubMed2000

A matched cohort comparison of a criminal justice system's response to child sexual abuse: a profile of perpetrators.

OBJECTIVE: This study was undertaken to examine whether alleged child sexual abuse perpetrators are handled differently by the courts than other alleged felony perpetrators. Comparisons were made from the time of prosecutorial case acceptance through prosecution to sentencing, with emphasis on judicial and prosecutorial decision-making and plea-bargaining. METHOD: Data were retrospectively abstracted on the entire defendant population of cases of sexual abuse of children and adolescents (ages 2-17) over a 5-year period. Using a case-flow analysis, comparisons were made between a child sexual abuse cohort and a cohort of matched felony cases from a single jurisdiction. RESULTS: Three important findings emerged. First, compared to other felons, abuse perpetrators were employed, had been married, were mostly European American, and were older than 30 years of age. Second, in the abuse cohort, as many as 14% had a previous sexual or violent record compared to 2% in the comparison group. Third, similar percentages of perpetrators in both groups were released on their own recognizance, had the charges against them dropped, and were found guilty. As well, no differences between groups were found in the proportion of individuals sentenced to jail, probation, counseling, or work release. CONCLUSIONS: Although the treatment of perpetrators of child sexual abuse was similar to the treatment of perpetrators of other felonies, the profile of the child abuse perpetrator was quite different. Knowledge about this profile may impact prosecution or treatment and recidivism rates, to the extent that recidivism is related to characteristics of the abuse perpetrator.

Adolescent↗

PubMed1999

Agreement and repeatability of infrared pupillometry and the comparison method.

OBJECTIVE: To evaluate the accuracy and repeatability of the widely used comparison method of measuring pupil size. DESIGN: Cross-sectional study. PARTICIPANTS: Fourteen eyes of seven healthy myopic subjects were examined. INTERVENTION: Two examiners made two repeated measures of pupil diameters of 14 eyes using Rosenbaum card comparison pupillometry and infrared pupillometry. Subjects fixated on a distant visual acuity chart, and pupils were measured under three luminance conditions. The agreement and inter-rater repeatability of both methods were determined. MAIN OUTCOME MEASURES: Outcomes were pupil diameters, limits of agreement, and coefficient of repeatability of two examiners. RESULTS: The mean difference between the two techniques ranged from 0.3 to 0.5 mm. The limits of agreement within two standard deviations ranged from 2.4 to 2.8 mm. Coefficient of repeatability ranged from 0.6 to 1.4 mm for infrared pupillometry and 1.0 to 1.2 mm for Rosenbaum pupillometry. Inter-rater repeatability of Rosenbaum pupillometry was consistently pupil diameter biased. Pupil diameters measured with the Rosenbaum method were consistently larger than diameters measured with the infrared technique for both examiners under all luminance conditions. CONCLUSIONS: Results indicate that although the mean difference in techniques was small, the range of the agreement between the Rosenbaum and the infrared techniques was large. The Rosenbaum method consistently overestimated pupil diameters and was subject to inter-rater repeatability bias. Rosenbaum pupillometry may not be appropriate when accurate pupil measurements are required. The results have implications for many clinical trials in ophthalmology, including those evaluating refractive surgery that use Rosenbaum comparison pupillometry.

Adult↗

PubMed1985

Comparison of EMT blood pressure measurements with an automated blood pressure monitor: on scene, during transport, and in the emergency department.

Auscultation or palpation of blood pressure in critically ill patients by emergency medical technicians (EMTs) can be difficult, if not impossible, because of ambient noise, motion artifact, limited access to patients, or weak pulses. Automated blood pressure monitors (ABPMs) have been designed to overcome these problems during field emergencies and patient transport. Our study compared blood pressure measurements taken by EMTs with measurements provided by a Lifestat ABPM. Measurements in emergency patients on scene, during transport, in the emergency department (ED), and in a controlled environment were compared. Measurements in the various sites were obtained from 57 patients, and provision was made for two measurements at each site. Comparison of on-scene systolic blood pressures yielded a mean absolute systolic difference of 10.46 +/- 1.42 mm Hg and a mean absolute diastolic difference of 9.33 +/- 1.32 mm Hg. During transport systolic pressures showed a mean absolute difference of 11.50 +/- 1.72 mm Hg, and diastolic pressures showed a mean absolute difference of 7.59 +/- 1.16 mm Hg. Mean absolute differences in the ED were 11.23 +/- 1.49 mm Hg systolic and 8.37 +/- 1.25 mm Hg diastolic. Ninety comparison measurements in a controlled environment yielded a mean absolute systolic difference of 8.74 +/- 0.87 mm Hg and a mean absolute diastolic difference of 7.97 +/- 0.72 mm Hg. Comparison of mean diastolic pressure differences between EMT and ABPM measurements in various settings revealed some small, but statistically significant, discrepancies that were not considered clinically relevant.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Pressure↗

PubMed2001

A comparison of three models of 137Cs transfer in forest ecosystems.

The predictions of three models of 137Cs transfer in forest ecosystems (FOA, LOGNAT and FORESTLAND) were compared. The scenario for the model-model comparison consisted of an acute dry deposition of 137Cs over a coniferous forest. The model predictions were subsequently compared (model-data comparison) with values derived from experimental data measured in forests of the Bryansk region in Russia that were contaminated by the Chernobyl accident and that have similar characteristics to the forests described in the scenario. The predictions of radiocaesium levels in the litter-soil layer, berries, needles, wood, whole tree and moose made with the models were in relatively good agreement with each other (within a factor of 1.4-2.9). The best agreement was observed for berries and moose and the worst for wood. There was also good agreement between the model predictions for the same variables and the experimental data (within a factor of 1.2 3.2). In this case, the best agreement was observed for the litter-soil layer and the worst for wood and the whole tree. Overall, at least for the studied scenario and for the first 10 years after deposition, any of the models can be used if the final aim is to estimate average concentrations in different forest components. The agreement between the model predictions worsens with time and there were differences in the form of the time dependencies predicted by the models, especially for wood. This may lead to larger differences between the model predictions and the experimental data for times beyond the period for which data were available for comparison (10 years after the deposition).

Cesium Radioisotopes↗

PubMed2000

Differences in quality of life across renal replacement therapies: a meta-analytic comparison.

A meta-analysis compared emotional distress and psychological well-being across renal replacement therapies (RRTs) and examined whether differences could be explained by: (1) treatment modalities, (2) case mix, or (3) methodologic rigor. Standard meta-analytic procedures were used to evaluate published comparative studies. Successful renal transplantation was associated with: (1) lower distress (effect size, d = -0.43 SD) and greater well-being (d = 0. 62 SD) than in-center hemodialysis (CHD) and (2) lower distress (d = -0.29 SD) and greater well-being (d = 0.53 SD) than continuous ambulatory peritoneal dialysis (CAPD). CAPD was characterized by greater well-being (d = 0.18 SD) than CHD and CHD was associated with greater distress (d = 0.16 SD) than home hemodialysis. Although methodologic rigor and case-mix differences did not correlate with the magnitude of psychosocial differences across RRTs, 10 of the 12 comparisons (83%) were threatened by publication bias (ie, that nonsignificant comparisons may have been underrepresented in the published literature). Thus, although significant quality-of-life differences were evident across treatment groups, the types of patients representative of the various RRTs also differed significantly in terms of case-mix variables relevant to psychosocial well-being and emotional distress. Published findings indicating differential quality of life across RRTs may thus be attributable to: (1) valid differences in effective renal replacement, reduced medical complications, and lifestyles afforded by these treatment modalities; (2) case-mix differences in the patient samples selected to represent them in research comparisons; or (3) both of these alternative explanations.

Adolescent↗

PubMed1999

A dosimetric comparison of fan-beam intensity modulated radiotherapy with Gamma Knife stereotactic radiosurgery for treating intermediate intracranial lesions.

PURPOSE: To compare and evaluate treatment plans for the fan-beam intensity modulated radiotherapy and the Gamma Knife radiosurgery for treating medium-size intracranial lesions (range 4-25 cm3). METHODS AND MATERIALS: Treatment plans were developed for the Leksell Gamma Knife and a fan-beam inverse treatment planning system for intensity modulated radiotherapy. Treatment plan comparisons were carried out using dose-volume histogram (DVH), tissue-volume ratio (TVR), and maximum dose to the prescription dose (MDPD) ratio. The study was carried out for both simulated targets and clinical targets with irregular shapes and at different locations. RESULTS: The MDPD ratio was significantly greater for the Gamma Knife plans than for the fan-beam IMRT plans. The Gamma Knife plans produced equivalent TVR values to the fan-beam IMRT plans. Based on the DVH comparison, the fan-beam IMRT delivered significantly more dose to the normal brain tissue than the Gamma Knife. The results of the comparison were found to be insensitive to the target locations. CONCLUSION: The Gamma Knife is better than the fan-beam IMRT in sparing normal brain tissue while producing equivalent tumor dose conformity for treating medium-size intracranial lesions. However, the target dose homogeneity is significantly better for the fan-beam IMRT than for the Gamma Knife.

Brain Neoplasms↗