bluuebunny/crossref_metadata_2025_split huggingface dataset:
Leptin kinetics during peritoneal dialysis in acutely uraemic rats
Authors: MATSUBARA KEISUKE , KIYOMOTO HIDEYASU , MORIWAKI KUMIKO , HARA TAIGA , KONDO NAOKI , SHOKOJI TAKATOMI , HITOMI HIROFUMI , AKI YASUHARU , AONO MASAKI , NISHIYAMA AKIRA , OHMORI KOJI , KOHNO MASAKAZU 
Published: October 2004

SUMMARY:Background:  Leptin has been shown to function as an inhibitor of appetite and energy expenditure accelerator. However, it was recently reported that leptin has other important functions as a fibrogenetic factor and a novel, independent risk factor for coronary heart disease. The present study aimed to assess the blood concentration of leptin in acute uraemic rats by using various peritoneal dialysis (PD) solutions.Methods:  To induce acute renal failure, the bilateral renal arteries were ligated via a mid‐abdominal incision 1 h before starting PD. Rats were divided into four groups: 13.6 g/L glucose‐containing dialysate (group L); 38.6 g/L glucose‐containing dialysate (group H); 13.6 g/L glucose‐ and 25 g/L mannitol‐containing dialysate with equal osmotic pressure to the dialysate of group H (group M); and renal failure without PD (group F). The concentrations of glucose, urea nitrogen (UN), leptin and insulin were measured at 0, 2 and 4 h after starting PD.Results:  We observed significant blood UN suppression in all dialysed groups. Blood glucose was significantly higher in rats treated with the high glucose solution than in those treated with the low glucose solution. Insulin and leptin significantly increased in the high glucose solution group. There was a strong correlation between the blood glucose and insulin levels. We also found a strong correlation between the percentage changes in blood glucose and leptin. The relationship between the percentage changes in insulin and leptin were weak but significant.Conclusion:  The high glucose PD solution resulted in increased circulating levels of leptin, glucose, and insulin, suggesting that these changes are linked with PD performed with glucose‐based dialysis fluid.
Effects of calcium antagonists in hypertensive patients with renal dysfunction: A prospective, randomized, parallel trial comparing benidipine and nifedipine
Authors: INOUE SANAE , TOMINO YASUHIKO 
Published: October 2004

SUMMARY:Background:  Although calcium antagonists, derived from dihydropyridine (DHP), are important agents in achieving control in a majority of patients with high blood pressure and renal disease, there are no comparative data regarding their inhibitory effects on the progression of renal dysfunction in Japan.Methods:  Benidipine and nifedipine retard both calcium antagonists derived from DHP and were compared in terms of their inhibitory effect on the progression of renal dysfunction in hypertensive patients. The primary end‐points were defined as 1.5 times the serum creatinine value at baseline, progression to end‐stage renal failure (ESRF) necessitating dialysis or renal transplantation, and death.Results:  During the study period, a significant decline in blood pressure was observed in the two groups, with no significant difference between them. The worsening of nephropathy was significantly inhibited in the benidipine group as compared with the nifedipine retard group (log‐rank test: P = 0.014, Wilcoxon's test: P = 0.022). Among the subjects who reached a primary end‐point, one (33%) in the benidipine group and five (50%) in the nifedipine retard group were placed on haemodialysis within 1 year.Conclusion:  It appears that benidipine inhibits the progression of hypertensive renal diseases more effectively than nifedipine retard.
Polymorphism of renin‐angiotensin system genes in IgA nephropathy
Authors: WOO KENG‐THYE , LAU YEOW‐KOK , CHOONG LINA HL , ZHAO YI , TAN HWEE‐BOON , FOOK‐CHONG STEPHANIE , TAN ENG‐KING , YAP HUI‐KIM , WONG KOK‐SENG 
Published: October 2004

SUMMARY:Background and Aims:  Individuals are prone to disease because of certain disease‐susceptible genes. The angiotensin I‐converting enzyme (ACE) gene insertion/deletion (I/D), the angiotensinogen (AGT) gene, M235T, and the angiotensin II type 1 receptor (ATR) gene, A1166C, polymorphisms have been associated with IgA nephropathy (IgAN) and its progression. Several studies on Caucasians and Japanese patients have reported contradictory results. We determined these polymorphisms in 118 Chinese patients with IgAN and 94 healthy Chinese subjects to assess their clinical impact.Methods:  Genotyping was performed with DNA isolated from peripheral leucocytes, polymerase chain reaction amplification of the polymorphic sequence, restriction enzymes digestion, and separation and identification of DNA fragments. Clinical data at renal biopsy and final status on renal function were determined from patients’ records.Results:  Comparing all IgAN patients with controls, AGT and ATR genotype distributions were similar, whereas there was a significant increase in the ACE DD genotype (P < 0.05). When comparing patients with end‐stage renal failure (IgAN‐ESRF) and those without (IgAN‐nonESRF), there was no difference among the three gene polymorphisms. In contrast, there were significant differences in higher male prevalence (P < 0.05), increased serum creatinine at presentation (P < 0.05), more sclerosis (P < 0.01) and higher tubulointerstitial lesion score (P < 0.001) in the IgAN‐ESRF group.Conclusion:  Among the ACE, AGT and ATR gene polymorphisms, only the DD genotype may predispose the individual to IgAN in the Chinese population. None are significant for prognosticating ESRF.
Angiotensin II facilitates autoregulation in the perfused mouse kidney: An optimized in vitro model for assessment of renal vascular and tubular function
Authors: RAHGOZAR MAJID , GUAN ZHENGRONG , MATTHIAS ANITA , GOBÉ GLENDA C , ENDRE ZOLTÁN H 
Published: October 2004

SUMMARY: Background and Aims:  We have optimized the isolated perfused mouse kidney (IPMK) model for studying renal vascular and tubular function in vitro using 24–28 g C57BL6J mice; the wild type controls for many transgenic mice.Methods and Results:  Buffer composition was optimized for bovine serum albumin concentration (BSA). The effect of adding erythrocytes on renal function and morphology was assessed. Autoregulation was investigated during stepped increases in perfusion pressure. Perfusion for 60 min at 90–110 mmHg with Krebs bicarbonate buffer containing 5.5% BSA, and amino acids produced functional parameters within the in vivo range. Erythrocytes increased renal vascular resistance (3.8 ± 0.2 vs 2.4 ± 0.1 mL/min.mmHg, P < 0.05), enhanced sodium reabsorption (FENa = 0.3 ± 0.08 vs 1.5 ± 0.7%, P < 0.05), produced equivalent glomerular filtration rates (GFR; 364 ± 38 vs 400 ± 9 µL/min per gkw) and reduced distal tubular cell injury in the inner stripe (5.8 ± 1.7 vs 23.7 ± 3.1%, P < 0.001) compared to cell free perfusion. The IPMK was responsive to vasoconstrictor (angiotensin II, EC50 100 pM) and vasodilator (methacholine, EC50 75 nM) mediators and showed partial autoregulation of perfusate flow under control conditions over 65–85 mmHg; autoregulatory index (ARI) of 0.66 ± 0.11. Angiotensin II (100 pM) extended this range (to 65–120 mmHg) and enhanced efficiency (ARI 0.21 ± 0.02, P < 0.05). Angiotensin II facilitation was antagonized by methacholine (ARI 0.76 ± 0.08) and papaverine (ARI 0.91 ± 0.13).Conclusion:  The IPMK model is useful for studying renal physiology and pathophysiology without systemic neurohormonal influences.
Long‐term recombinant human growth hormone use in Australian children with renal disease
Authors: CROMPTON CHARLES H ,   the Australian and New Zealand Paediatric Nephrology Association
Published: October 2004

SUMMARY:Background:  Recombinant human growth hormone (rhGH) has been used for 15 years to treat Australian children with short stature caused by chronic kidney disease. The Australia‐wide growth hormone database, OZGROW, has prospectively collected data for all patients treated with rhGH. The impact of rhGH therapy on linear growth in patients with chronic renal failure (CRF) was assessed by retrospectively analysing this data.Methods:  Growth data prior to and during treatment, bone age, and pubertal data were recorded from the database. Questionnaire data provided further information on underlying renal disease, medication use, bone disease, and final height. Patients were classified according to treatment modality; conservative management of CRF, haemodialysis or peritoneal dialysis, and transplant.Results:  Data on 183 patients were analysed. The duration of rhGH therapy ranged from 1.2 to 10.5 years (mean 5.3 years). The height standard deviation score (Ht SDS) in each patient group at the start and end of rhGH treatment were as follows: Predialysis: −2.6 to −2.1; dialysis: −2.7 to −2.3; transplant: −3.1 to −2.8 (P = 0.0001). Thirty‐nine patients achieved final adult height, with mean Ht SDS before rhGH therapy being −2.65, and at final height it was 2.3. The mean final height for the males was 161.8 cm and for the females, it was 149.5 cm.Conclusion:  The effect of treatment with rhGH was less dramatic than reported in the literature. However, the positive benefit of rhGH therapy was apparent both in the short and long‐term. Therapy with rhGH maintained a steady Ht SDS with time; without rhGH, it would be anticipated that many children would show a steady decline in Ht SDS. The maximum benefit was seen in preterminal renal failure, and early therapy (before dialysis or transplantation) is recommended before an irrecoverable loss of height potential occurs.
Macrophage accumulation and renal fibrosis are independent of macrophage migration inhibitory factor in mouse obstructive nephropathy
Authors: RICE EDWINA K , NIKOLIC‐PATERSON DAVID J , DAVID JOHN R , BUCALA RICHARD , METZ CHRISTINE N , ATKINS ROBERT C , TESCH GREGORY H 
Published: October 2004

SUMMARY:Background and Aim:  The progression of renal injury, initiated by either an immune or non‐immune insult, is closely associated with the accumulation of leucocytes and fibroblasts in the damaged kidney. Macrophage migration inhibitory factor (MIF) regulates leucocyte activation and fibroblast proliferation in vitro. Studies have identified a pathological role for MIF in immune‐initiated renal injury in the rat. In this study, we examined the role of MIF in obstructive nephropathy, where renal injury is initiated by a non‐immune insult.Methods and Results:  Unilateral ureteric ligation was performed on MIF wildtype (+/+) and MIF deficient (–/–) mice. Groups of five mice were killed at days 0, 1, 5 or 10 after obstruction, and kidneys were examined via immunohistochemistry and northern blotting. In MIF +/+ mice, expression of the MIF protein increased in obstructed kidneys compared to normal control kidneys. Interstitial macrophage and T cell accumulation was significantly increased in obstructed kidneys at day 5 and 10, but was unaffected by MIF deficiency. Osteopontin and macrophage colony stimulating factor (M‐CSF) mRNA expression in obstructed kidneys were equally increased in both genotypes, indicating that expression of these chemokines is not influenced by MIF. No difference was detected in the development of renal fibrosis in obstructed MIF +/+ and MIF –/– kidneys, as assessed by myofibroblast accumulation and proliferation and expression of profibrotic molecules (transforming growth factor‐beta 1(TGF‐β1) and collagen).Conclusion:  These results demonstrate that MIF expression is increased in obstructive nephropathy without affecting kidney leucocyte accumulation or the development of renal fibrosis. This suggests that the progression of renal injury in obstructive nephropathy is independent of MIF.
Assessing Interaction Effects in Linear Measurement Error Models
Authors: Huang Li-Shan , Wang Hongkun , Cox Christopher 
Published: October 2004

Summary
In a linear model, the effect of a continuous explanatory variable may vary across groups defined by a categorical variable, and the variable itself may be subject to measurement error. This suggests a linear measurement error model with slope-by-factor interactions. The variables that are defined by such interactions are neither continuous nor discrete, and hence it is not immediately clear how to fit linear measurement error models when interactions are present. This paper gives a corollary of a theorem of Fuller for the situation of correcting measurement errors in a linear model with slope-by-factor interactions. In particular, the error-corrected estimate of the coefficients and its asymptotic variance matrix are given in a more easily assessable form. Simulation results confirm the asymptotic normality of the coefficients in finite sample cases. We apply the results to data from the Seychelles Child Development Study at age 66 months, assessing the effects of exposure to mercury through consumption of fish on child development for females and males for both prenatal and post-natal exposure.
Mixture Model on the Variance for the Differential Analysis of Gene Expression Data
Authors: Delmar Paul , Robin Stéphane , Tronik-Le Roux Diana , Daudin Jean Jacques 
Published: October 2004

Summary
In microarray experiments, accurate estimation of the gene variance is a key step in the identification of differentially expressed genes. Variance models go from the too stringent homoscedastic assumption to the overparameterized model assuming a specific variance for each gene. Between these two extremes there is some room for intermediate models. We propose a method that identifies clusters of genes with equal variance. We use a mixture model on the gene variance distribution. A test statistic for ranking and detecting differentially expressed genes is proposed. The method is illustrated with publicly available complementary deoxyribonucleic acid microarray experiments, an unpublished data set and further simulation studies.
A Survival-Adjusted Quantal Response Test for Comparing Tumour Incidence Rates
Authors: Peddada Shyamal D. , Dinse Gregg E. , Haseman Joseph K. 
Published: October 2004

Summary
The paper presents a case-study of skin fibromas among male rats in the 2-year cancer bioassay of methyleugenol that was conducted by the US National Toxicology Program (NTP). In animal carcinogenicity experiments such as this one, tumour rates are often compared with the Cochran–Armitage (CA) trend test. The operating characteristics of the CA test, however, can be adversely affected by survival differences across groups and by the assumed dose metric. Survival-adjusted generalizations of the CA test have been proposed, but they are still sensitive to the choice of scores that are assigned to the dose groups. We present an alternative test, which outperforms the survival-adjusted CA test which is currently used by the NTP to compare incidence rates. Simulated data from a wide range of realistic situations show that the operating characteristics of the test proposed are superior to those of the NTP’s survival-adjusted CA test, especially for rare tumours and wide logarithmic spacings of the dose metric.
Limits of Quantitation for Laboratory Assays
Authors: Cox Christopher 
Published: October 2004

SummaryA common problem with laboratory assays is that a measurement of a substance in a test sample becomes relatively imprecise as the concentration decreases. A standard solution is to establish lower limits for reliable measurement. A quantitation limit is a level above which a measurement has sufficient precision to be reliably reported. The paper proposes a new approach to defining the limit of quantitation for the case where a linear calibration curve is used to estimate actual concentrations from measured values. The approach is based on the relative precision of the estimated concentration, using the delta method to approximate the precision. A graphical display is proposed for the assessment of estimated concentrations, as well as the overall reliability of the calibration curve. Our research is motivated by a clinical inhalation experiment. Comparisons are made between the approach proposed and two standard methods, using both real and simulated data.
An Individual Measure of Relative Survival
Authors: Stare Janez , Henderson Robin , Pohar Maja 
Published: October 2004

Summary
Relative survival techniques are used to compare survival experience in a study cohort with that expected if background population rates apply. The techniques are especially useful when cause-specific death information is not accurate or not available as they provide a measure of excess mortality in a group of patients with a certain disease. Whereas these methods are based on group comparisons, we present here a transformation approach which instead gives for each individual an outcome measure relative to the appropriate background population. The new outcome measure is easily interpreted and can be analysed by using standard survival analysis techniques. It provides additional information on relative survival and gives new options in regression analysis. For example, one can estimate the proportion of patients who survived longer than a given percentile of the respective general population or compare survival experience of individuals while accounting for the population differences. The regression models for the new outcome measure are different from existing models, thus providing new possibilities in analysing relative survival data. One distinctive feature of our approach is that we adjust for expected survival before modelling. The paper is motivated by a study into the survival of patients after acute myocardial infarction.
Assessing Accuracy of a Continuous Screening Test in the Presence of Verification Bias
Authors: Alonzo Todd A. , Pepe Margaret Sullivan 
Published: October 2004

Summary
In studies to assess the accuracy of a screening test, often definitive disease assessment is too invasive or expensive to be ascertained on all the study subjects. Although it may be more ethical or cost effective to ascertain the true disease status with a higher rate in study subjects where the screening test or additional information is suggestive of disease, estimates of accuracy can be biased in a study with such a design. This bias is known as verification bias. Verification bias correction methods that accommodate screening tests with binary or ordinal responses have been developed; however, no verification bias correction methods exist for tests with continuous results. We propose and compare imputation and reweighting bias-corrected estimators of true and false positive rates, receiver operating characteristic curves and area under the receiver operating characteristic curve for continuous tests. Distribution theory and simulation studies are used to compare the proposed estimators with respect to bias, relative efficiency and robustness to model misspecification. The bias correction estimators proposed are applied to data from a study of screening tests for neonatal hearing loss.
A Hierarchical Bayesian Model for Predicting the Functional Consequences of Amino-Acid Polymorphisms
Authors: Verzilli Claudio J. , Whittaker John C. , Stallard Nigel , Chasman Daniel 
Published: October 2004

Summary
Genetic polymorphisms in deoxyribonucleic acid coding regions may have a phenotypic effect on the carrier, e.g. by influencing susceptibility to disease. Detection of deleterious mutations via association studies is hampered by the large number of candidate sites; therefore methods are needed to narrow down the search to the most promising sites. For this, a possible approach is to use structural and sequence-based information of the encoded protein to predict whether a mutation at a particular site is likely to disrupt the functionality of the protein itself. We propose a hierarchical Bayesian multivariate adaptive regression spline (BMARS) model for supervised learning in this context and assess its predictive performance by using data from mutagenesis experiments on lac repressor and lysozyme proteins. In these experiments, about 12 amino-acid substitutions were performed at each native amino-acid position and the effect on protein functionality was assessed. The training data thus consist of repeated observations at each position, which the hierarchical framework is needed to account for. The model is trained on the lac repressor data and tested on the lysozyme mutations and vice versa. In particular, we show that the hierarchical BMARS model, by allowing for the clustered nature of the data, yields lower out-of-sample misclassification rates compared with both a BMARS and a frequen-tist MARS model, a support vector machine classifier and an optimally pruned classification tree.
Generalized Additive Modelling of Sample Extremes
Authors: Chavez-Demoulin V. , Davison A. C. 
Published: October 2004

SummaryWe describe smooth non-stationary generalized additive modelling for sample extremes, in which spline smoothers are incorporated into models for exceedances over high thresholds. Fitting is by maximum penalized likelihood estimation, with uncertainty assessed by using differences of deviances and bootstrap simulation. The approach is illustrated by using data on extreme winter temperatures in the Swiss Alps, analysis of which shows strong influence of the north Atlantic oscillation. Benefits of the new approach are flexible and appropriate modelling of extremes, more realistic assessment of estimation uncertainty and the accommodation of complex dependence patterns.
Low Dose Risk Estimation via Simultaneous Statistical Inferences
Authors: Piegorsch Walter W. , Webster West R. , Pan Wei , Kodell Ralph L. 
Published: October 2004

Summary
The paper develops and studies simultaneous confidence bounds that are useful for making low dose inferences in quantitative risk analysis. Application is intended for risk assessment studies where human, animal or ecological data are used to set safe low dose levels of a toxic agent, but where study information is limited to high dose levels of the agent. Methods are derived for estimating simultaneous, one-sided, upper confidence limits on risk for end points measured on a continuous scale. From the simultaneous confidence bounds, lower confidence limits on the dose that is associated with a particular risk (often referred to as a bench-mark dose) are calculated. An important feature of the simultaneous construction is that any inferences that are based on inverting the simultaneous confidence bounds apply automatically to inverse bounds on the bench-mark dose.
A Unified Model for Covariate Measurement Error Adjustment in an Occupational Health Study While Accounting for Non-Detectable Exposures
Authors: Wannemuehler Kathleen A. , Lyles Robert H. 
Published: October 2004

Summary
The paper focuses on an occupational health study where the goal is to associate a worker’s true log-normal-scale mean dust exposure over the year with forced expiratory volume. A previous analysis used repeated shift-long dust exposure measurements, taken over a year, as a surrogate to address the issue of the mean exposure being unobservable. However, in this study the associated measurement error is further complicated by the fact that some exposure measurements fall below a detectable limit. We extend the previous analysis via full maximum likelihood, to account appropriately for non-detectable exposures.