bluuebunny/crossref_metadata_2025_split huggingface dataset:
Examining neighbourhood confounding in a survey: An example using the National Health and Nutrition Examination Survey II
Authors: Korn Edward L. , Graubard Barry I. 
Published: April 2007

AbstractThis paper demonstrates a methodology for examining whether neighbourhood stratification lessens the confounding bias of some specific risk‐factor/disease associations in analysis of the National Health and Nutrition Examination Survey II (NHANES II). The fortuitous clustering of the sample design of NHANES allows us to estimate risk‐factor/disease associations with and without controlling for neighbourhood effects on the same population. We briefly discuss the implications of this methodology for neighbourhood matching in case‐control studies.
Drug treatment of mild hypertension to reduce the risk of CHD: Is it worth‐while?
Authors: Holme Ingar 
Published: April 2007

AbstractAlthough hypertension is regarded as a causal factor for coronary heart disease (CHD) a reduction in the risk of CHD as a result of lowering blood pressure in mild hypertension could not be demonstrated. This conclusion is based on an overview analysis of all published randomized trials in mild hypertension, including more than 25,000 subjects contributing over 125,000 person years of observation.There is evidence that treatment reduces the risk of CHD in moderate to severe hypertension. In addition the pooling of four clinical trials with treated control groups indicates a reduction in the risk of CHD of borderline significance with β‐blockers or aggressive treatment when compared with standard treatment (mostly diuretics).The failure of drug treatment to reduce the risk of CHD in mild hypertension is consistent with the results from epidemiological studies because of derangement of the lipid profile induced by diuretics and β‐blockers.
Remission duration: An example of interval‐censored observations
Authors: Rücker Gerta , Messerer Dorle 
Published: April 2007

AbstractRemission duration data from two observational studies, the German ALL/AUL study on acute lymphoblastic and acute undifferentiated leukaemia and the Kiel Lymphoma Study, are used to demonstrate the adequacy of an interval‐censoring approach. The Turnbull estimator is contrasted with the conventionally used Kaplan—Meier estimator. In addition, a parametric model is used for estimation or simulation of the delay times of complete remission diagnosis and relapse diagnosis. Two possible consequences of the conventional approach are discussed: biased estimation (for example, overestimation of remission duration), and underestimation of the true error variance, which may lead to false positive results. On the other hand, the applicability of the interval‐censoring approach is doubtful when the censoring mechanism (examination pattern, patient's behaviour) is confounded with the endpoints.
A test to detect clustering applied to muscle fibres
Authors: Howel Denise 
Published: April 2007

AbstractThe random arrangement of a chosen uncommon element type within a mosaic has been assessed by the new statistics, ‘Number of Clusters’ and ‘Mean Cluster Size’. Their distributions were obtained by simulation assuming the mosaic has a hexagonal arrangement. When this assumption was relaxed to allow mosaics nearer to those observed in nature, the results were little changed. This method was then applied to a set of muscle fibre data to test hypotheses about the likely targets in inflammatory muscle disorders.
Prescription sequence analysis: A new and fast method for assessing certain adverse reactions of prescription drugs in large populations
Authors: Petri H. , De Vet H. C. W. , Naus J. , Urquhart J. 
Published: April 2007

AbstractPrescription sequence analysis (PSA) uses pharmacy‐based prescription drug histories to detect a subset of drug effects: those that are themselves indications for changes in the prescribing of another drug. Dutch pharmacy practice ensures virtually complete drug histories. With a database of 25,000 patients, we used PSA to test an alleged link between the use of the anti‐vertigo drug flunarizine and mental depression. The temporal sequence of anti‐depressant use among flunarizine users shows no clustering that would suggest a causal link. PSA can be run within a few days, which may make it helpful in resolving certain of the periodic controversies about adverse drug reactions.
Explanatory and pragmatic estimates of the treatment effect when deviations from allocated treatment occur
Authors: Newcombe R. G. 
Published: April 2007

AbstractIn a randomized clinical trial comparing two treatments it can happen that certain patients receive the treatment other than that determined by random allocation. Significance testing is usually performed by ‘intention to treat’, that is, comparison of groups as determined by random allocation. The difference between the mean values of the outcome variable for these two groups estimates the difference in practical use between two treatment policies, corresponding to a pragmatic approach. An attenuation factor can then be used to obtain an estimate of the underlying difference in effectiveness between the two treatments, corresponding to an explanatory paradigm. Thus two distinct estimates are obtained; in many instances both are valid, but have distinct interpretations. Correspondingly, in planning sample size requirements when deviations from allocated treatment can be anticipated, the target treatment difference may be understood in either an explanatory or a pragmatic sense; for the sample size assessment method it is necessary to take this distinction into account.
Optimal placebo response rates for comparing two binomial proportions
Authors: Day Simon J. 
Published: April 2007

AbstractThis paper considers the problem of comparing proportions in clinical trials where two parallel groups are studied. The question of what will happen to the response rate of an active therapy if some external factor affects the placebo rate is asked and two different, but similar, answers are proposed. Assuming either a logistic or probit model has substantial influence on the sample size required to detect differences and optimal comparisons are suggested. The idea is illustrated by a clinical trial of treatment for peptic ulcer and suggestions for other possible applications are presented.
Inborn/outborn status and neonatal survival: A meta‐analysis of non‐randomized studies
Authors: Ozminkowski Ronald J. , Wortman Paul M. , Roloff Dietrich W. 
Published: April 2007

AbstractWe have applied meta‐analysis to investigate the relationship between birth place and the likelihood of neonatal survival, for infants of low birth weight (< 2501 grams) in a series of 19 non‐randomized studies. This paper illustrates the utility meta‐analysis in evaluating medical technologies described in non‐randomized studies, if proper attention is given to biases in those studies. The results of this meta‐analysis show strong preferences for inborn status, especially for infants who weigh 1001—2000 grams. For infants of lower or higher birth weight (that is, < 1001 or > 2000 grams), the studies are inconsistent: some favour inborn status while others favour outborn status. This heterogeneity is not surprising, because selection bias is more problematic in studies of infants at these birth weights. We discuss potential causes of and solutions to selection bias and illustrate its potential magnitude by introducing thebias factor, which should be considered in the design of future studies. When selection bias cannot be ruled out, the results shown for those who weigh 1001—2000 grams are more appropriate for generating valid conclusions and subsequent policies regarding birth place preference for low birth weight infants.
Using association models to analyse agreement data: Two examples
Authors: Becker Mark P. 
Published: April 2007

AbstractTwo examples demonstrate how one can use association models to analyse agreement data. The first example concerns intra‐rater variability in the classification of sputum cytology slides, and the second deals with variability associated with the reporting of passive smoking histories. The paper emphasizes models in which one estimates category scores from the data, that is models that are not in the log‐linear family of models. Such models have use in assessment of category distinguishability and provide insights not easily obtained with log‐linear models.
Analysis of epidemiologic case—base studies for binary data
Authors: Nurminen Markku 
Published: April 2007

AbstractRecent developments in statistical methods for epidemiology have revived the application of sampling techniques in the design and analysis of cohort studies. The ‘case — base’ design involves sampling of both the cases and the cohort base of the study. This paper reviews some data‐analytic imperfections of the approaches to risk ratio estimation, and modifies and advances a consistent likelihood‐based procedure — analogous to Miettinen and Nurminen's proposal for a full cohort design — for interval estimation (and also point estimation and significance testing) in the context of binary case—base data. First, the procedure avoids the use of Taylor‐series approximations to derive variance estimators for non‐linear functions of parameters. Second, the asymptotic condition effects a simple computational expression for the chi‐square function of risk ratios that is universally applicable to small samples. The statistical modelling underlying the method allows inferences about risk ratios without the assumption of rare disease either for the general population or for a particular base. The paper also extends the analysis to encompass stratified data. Finally, a numerical evaluation evinced the accurate small‐sample properties of the proposed method.
A note on confidence limits for quartiles with right censored data
Authors: Elashoff R. M. , Lee J. J. , Afifi A. A. 
Published: April 2007

AbstractTwo new methods are proposed for constructing the confidence limits for quartiles. The small sample behaviour of these two methods is compared with the Jennison and Turnbull modified Brookmeyer—Crowley method at three quartiles. The simulation study indicates that one of the new methods, the smoothed modified reflected method, is preferred over the other methods when the censoring rate is less than 40 per cent while the Jennison and Turnbull method is preferred for higher censoring. The results for the upper quartile are similar to the median. For the lower quartile with small sample and high censoring, semi‐infinite intervals may often occur. The correct practice is to permit the semi‐infinite intervals without modifying them since it is more informative and gives closer to nominal level coverage.
Spatial XRF distribution characteristics associated with polarized EDXRF spectrometry
Authors: Zhan Xiuchun , Luo Liqiang , Fan Xingtao 
Published: April 2007

AbstractAn experiment was designed and carried out to measure the XRF yield distribution over the area irradiated by the target's x‐rays in a polarized EDXRF spectrometer. A small solder disc, which was made of mainly lead and tin and with a diameter of about 3 mm, was scanned manually with equal displacements over the area. XRF spectra excited by radiation from three typical targets, namely, highly oriented pyrolytic graphite (HOPG), Mo and Al2O3, were collected. Intensities of Sn Kα and Lα and Pb Lα and Mα lines were obtained and used to describe the XRF yield distributions from different targets. The results showed that the total areas contributing to the XRF signal were over 2 cm2 for the above three targets. Also, Pb Mα and Sn Kα maps irradiated by HOPG and Al2O3, respectively, showed very high intensities in the central parts, while they were very low in the periphery. The sum of intensities from four spots in central area (corresponding to about 7 × 7 mm2) represents about 50% of overall integrated intensities of the 33 measured spots. Also, the sharpest areas of Pb Mα and Sn Kα were slightly shifted. Pb Lα maps obtained using the Mo target showed much larger distribution areas, with center being the most intense and becoming weaker gradually toward the outer parts. The relatively small irradiation areas of the polarized targets may require better sample homogeneity, and care should be taken when small pieces of samples are to be analyzed. Copyright © 2007 John Wiley & Sons, Ltd.
Stapled Transanal Rectal Resection (Starr) to Reverse the Anatomic Disorders of Pelvic Floor Dyssynergia
Authors: Pechlivanides George , Tsiaoussis John , Athanasakis Elias , Zervakis Nikolaos , Gouvas Nikolaos , Zacharioudakis George , Xynos Evaghelos 
Published: April 2007

AbstractAnterior rectocele and rectoanal intussusception are anatomic disorders related to excessive straining during defecation that usually manifest with symptoms of obstructive defecation. Stapled transanal rectal resection (STARR), a newly described surgical method for correcting these disorders, is considered a good alternative to the traditional transrectal approaches. The aim of the present study was to assess the early postoperative functional results of STARR. A total of 16 patients (13 female) were subjected to the STARR procedure during a period of 12 months. The presence of anatomic disorders of the anorectum was verified by dynamic defecography. Preoperative assessment also included colonic transit time, anal sphincter ultrasonography, and anorectal stationary manometry. Postoperative assessment included the same battery of tests. Altogether, 12 patients had rectoanal intussusception of > 2 cm and rectocele. In eight of them the anterior component of the rectocele was 2 to 4 cm, and in four it was > 4 cm. Four patients had a 1‐ to 2‐cm internal intussusception and a rectocele of < 2 cm. All of them reported evacuation difficulties, but none had significant incontinence. Preoperative endoscopy did not reveal the presence of a solitary ulcer in any of the patients. All females had had normal vaginal deliveries, and four of them were multiparous. No complications were encountered postoperatively, and the need for analgesics was minimal. At defecography, rectoanal anatomy was seen to be restored in all patients. Obstructive defecation symptoms remained rather unaffected in seven, disappeared in three, and improved significantly in the remaining six patients. The seven failures showed anismus at manometry and had biofeedback treatment with satisfactory results in five of them. Failure of the operation and biofeedback sessions to treat symptoms in those two cases was attributed to coexisting enterocele, which had been missed preoperatively. Immediately after surgery, most of the patients complained of urgency and frequent small motions that resolved spontaneously within 3 to 5 weeks in all but two cases. STARR is a safe, well tolerated surgical procedure that effectively restores anatomy and function of the anorectum in patients with anterior mucosal prolapse and rectoanal intussusception. Additional biofeedback treatment is usually necessary for further functional improvement. Failure may be the result of other coexisting anatomic and functional abnormalities of the pelvic floor.
Effect of excessive iodine exposure on the placental deiodinase activities andHoxc8expression during mouse embryogenesis
Authors: Yang Xue F. , Xu Jian , Guo Huai L. , Hou Xiao H. , Hao Li P. , Liu Lie G. , Sun Xiu F. 
Published: April 2007

Excessive iodine induces thyroid dysfunction. However, the effect of excessive iodine exposure on maternal–fetal thyroid hormone metabolism and on the expression of genes involved in differentiation, growth and development is poorly understood. Since a thyroid hormone receptor response element was found in theHoxc8promoter region,Hoxc8expression possibly regulated by excessive iodine exposure was firstly investigated. In the present study, Balb/C mice were given different doses of iodine in the form of potassium iodate (KIO3) at the levels of 0 (sterile water), 1·5, 3·0, 6·0, 12·0 and 24·0 μg/ml in drinking water for 4 months, then were mated. On 12·5 d postcoitum, placental type 2 and type 3 deiodinase activities and fetalHoxc8expression were determined. The results showed that excessive iodine exposure above 1·5 μg/ml resulted in an increase of total thyroxine and a decrease of total triiodothyronine in the serum of maternal mice, which was mainly associated with the inhibition of type 1 deiodinase activity in liver and kidney. Placental type 2 deiodinase activity decreased, showing an inverse relationship with maternal thyroxine level.Hoxc8 mRNA and protein expression at 12·5 d postcoitum embryos were down regulated. BecauseHoxc8plays an important role in normal skeletal development, this finding provides a possible explanation for the skeletal malformation induced by excessive iodine exposure and also provides a new clue to study the relationship between iodine or thyroid hormones andHoxgene expression pattern.
A randomised comparison of increase in serum 25-hydroxyvitamin D concentration after 4 weeks of daily oral intake of 10 μg cholecalciferol from multivitamin tablets or fish oil capsules in healthy young adults
Authors: Holvik Kristin , Madar Ahmed A. , Meyer Haakon E. , Lofthus Cathrine M. , Stene Lars C. 
Published: April 2007

Many types of vitamin supplements are available on the market, but little is known about whether cholecalciferol obtained from fat-containing capsules differs in bioavailability from that of solid tablets. Our objective was to test whether 4 weeks of daily supplementation with 10 μg cholecalciferol given as a fish oil capsule produces a larger increase in serum 25-hydroxyvitamin D (s-25(OH)D) concentration compared with the same dose of cholecalciferol given as a multivitamin tablet. A total of seventy-four healthy subjects aged 19–49 years were initially included and fifty-five of these completed the study and fulfilled the inclusion criteria. After completing a self-administered questionnaire about diet and sunshine exposure and having a non-fasting venous blood sample drawn, participants were randomised to receive daily multivitamin tablets (n 28) or fish oil capsules (n 27), each containing equal doses of cholecalciferol. A second blood sample was drawn after 28 d. Mean baseline s-25(OH)D was 40·3 (sd 22·0) nmol/l in the multivitamin group and 48·5 (24·8) nmol/l in the fish oil group. When controlling for baseline s-25(OH)D, mean 4-week increase in s-25(OH)D was 35·8 (95 % CI 30·9, 40·8) nmol/l in the multivitamin group and 32·3 (95 % CI 27·3, 37·4) nmol/l in the fish oil group; the mean difference was 3·5 (95 % CI − 3·6, 10·6) nmol/l (P = 0·33). The results were unaltered by statistical adjustment for BMI, ethnic background, age and sex. We conclude that fish oil capsules and multivitamin tablets containing 10 μg cholecalciferol administered over a 4-week period produced a similar mean increase in s-25(OH)D concentration.
Effect of raw or roasted whole soybeans on early lactational performance and ruminal and blood metabolites in Iranian cows
Authors: FATHI NASRI M. H. , DANESH MESGARAN M. , NIKKHAH A. , VALIZADEH R. , KEBREAB E. , FRANCE J. 
Published: April 2007

SUMMARYThe current study evaluated responses of early lactation Iranian Holstein cows to feeding roasted whole soybeans (SB) plus cottonseed meal (CSM), raw SB plus CSM and soybean meal (SBM) plus cottonseed (CS) in diets with lucerne hay and maize silage as the primary forage source. Treatments consisted of a total mixed ration that included 387 g forage/kg, supplemented with: (1) 120 g roasted SB/kg and 82 g CSM/kg, (2) 120 g raw SB/kg and 82 g CSM/kg, or (3) 120 g SBM/kg and 82 g CS/kg on a dry matter (DM) basis. Diets were offered to 14 multiparous Holstein cows (body weight=617·0 kg, days in milk=16·9) that were assigned randomly to one of three experimental diets for a 45-day trial. Dry matter intake (DMI) was significantly higher for the roasted SB plus CSM diet than for the raw SB plus CSM diet but the difference between the SB plus CSM diets and SBM plus CS was not significant. Yields of milk and 35 g fat-corrected milk (FCM)/kg and milk fat were significantly higher for the roasted SB plus CSM diet than for raw SB plus CSM and also for the SB plus CSM diets than for SBM plus CS. Milk protein concentration was significantly increased by about 2·0 g/kg by the SBM plus CS diet, but milk protein yield was the same for cows fed SBM plus CS, roasted SB plus CSM and raw SB plus CSM diets. Rumen ammonia N, plasma urea N (PUN) and milk urea N (MUN) concentrations were lower when the roasted SB plus CSM diet was fed. Ruminal pH and plasma glucose and β-hydroxybutyrate concentrations were not affected by dietary treatments. Plasma concentrations of essential amino acids (EAA), except Leu and Phe, were higher in cows fed the roasted SB plus CSM diet than in those fed raw SB plus CSM. The cows fed the SBM plus CS diet had the same concentrations of EAA, except Phe, as cows fed SB plus CSM diets. For diets based on lucerne hay and maize silage as the primary forage source, roasting of SB provides additional benefits over raw SB.
Isolating the ‘farmer’ effect as a component of the advantage of growing genetically modified varieties in developing countries: a Bt cotton case study from Jalgaon, India
Authors: MORSE S. , BENNETT R. , ISMAEL Y. 
Published: April 2007

SUMMARYThe present paper explores the ‘farmer’ effect in economic advantages often claimed for Bt cotton varieties (those with the endotoxin gene from Bacillus thuringiensis conferring resistance to some insect pests) compared to non-Bt varieties. Critics claim that much of the yield advantage of Bt cotton could be due to the fact that farmers adopting the technology are in a better position to provide inputs and management and so much of any claimed Bt advantage is an artefact rather than reflecting a real advantage of the variety per se. The present paper provides an in-depth analysis of 63 non-adopting and 94 adopting households of Bt cotton in Jalgaon, Maharashtra State, India, spanning the seasons 2002 and 2003. Results suggest that Bt adopters are indeed different from non-adopters in a number of ways. Adopters appear to specialize more on cotton (at least in terms of the land area they devote to the crop), spend more money on irrigation and grow well-performing non-Bt varieties of cotton (Bunny). Taking gross margin as the basis for comparison, Bt plots had 2·5 times the gross margin of non-Bt plots in both seasons. If only adopters are considered then the gross margin advantage of Bt plots reduces to 1·6 times that of non-Bt plots. This is still a significant advantage and could well explain the popularity of Bt in Maharashtra. However, it is clear that great care needs to be taken with such comparative studies.