bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antibodies directed against nitrosylated neoepitopes in sera of patients with human African trypanosomiasis
Authors: Semballa S. , Geffard M. , Daulouede S. , Malvy D. , Veyret B. , Lemesre J.‐L. , Holzmuller P. , Mnaimneh S. , Vincendeau P. 
Published: October 2004

SummaryAntibodies directed against nitrosylated epitopes have been found in sera from patients suffering from human African trypanosomiasis (HAT) but not in sera from control subjects living in the same endemic area or African control subjects living in France. We conjugated amino acids to albumin by glutaraldehyde (conjugates) and then nitrosylated the conjugates. Both conjugates and nitrosylated conjugates were analysed by enzyme‐linked immunosorbent assay (ELISA). We detected antibodies directed against nitrosylated l‐cysteine and l‐tyrosine conjugates; antibody levels were higher in stage II patients than in stage I. Patients with severe clinical signs had higher antibody levels, and antibody levels were highest in patients with major neurological signs. Antibody response was only associated with the IgM isotype. We evaluated antibody specificity and avidity by competition experiments using conjugates and nitrosylated conjugates. Avidity was around 2 ×10−6 m for the S‐nitroso‐cysteine epitope and 2 × 10−8 m for the S‐nitroso‐tyrosine epitope. Detection of circulating antibodies to S‐nitroso‐cysteine and S‐nitroso‐tyrosine epitopes provides indirect evidence for nitric oxide (NO) involvement in HAT and their levels are correlated with disease severity.
Diarrhoea, vomiting and the role of milk consumption: perceived and identified risk in Bamako (Mali)
Authors: Hetzel Manuel , Bonfoh Bassirou , Farah Zakaria , Traoré Malick , Simbé Cheick F. , Alfaroukh Idriss O. , Schelling Esther , Tanner Marcel , Zinsstag Jakob 
Published: October 2004

SummaryObjectives  To evaluate the public health impact of milk contamination in Bamako, Mali.Methods  A case–control study assessed the risk‐factors for food‐borne toxi‐infections with diarrhoea and vomiting as main clinical picture. A total of 131 schoolchildren between 5 and 20 years of age were interviewed by trained interviewers in schools in Bamako. A structured questionnaire was used to record health problems, food and particularly milk consumption habits and socio‐economic indicators.Results  Final multivariate logistic regression analysis identified regular consumption of boiled milk [odds ratio(OR) = 4.38; 95% CI = 1.15–16.71], age between 5 and 10 years (OR vs. age group 11–15 years = 3.28; 95% CI = 1.09–9.85) and the existence of dry latrines in the household (OR = 7.65; 95% CI = 1.92–30.55) as risk factors for diarrhoea and vomiting. Other milk products and the socio‐economic level of the household were not significantly associated with the outcome. Many people were unaware of the potential risks of milk consumption.Conclusions  Milk products may be a risk factor for food‐borne toxi‐infections. Attention has to be paid to products considered ‘safe’, such as boiled or pasteurized milk. The low awareness of potential risks of many people may increase the risk of milk consumption. To achieve a sustainable increase in local milk production in Africa, milk quantity and production and transformation quality should be improved simultaneously.
Evaluation of the direct agglutination test based on freeze‐dried Leishmania donovani promastigotes for the serodiagnosis of visceral leishmaniasis in Sudanese patients
Authors: Abdallah Khalid A. A. , Nour Bakri Y. M. , Schallig Henk D. F. H. , Mergani Adil , Hamid Zohal , Elkarim Abdallah Abd , Saeed Osman K. , Mohamadani Ahmed A. 
Published: October 2004

SummaryThe direct agglutination test (DAT) based on freeze‐dried (FD) Leishmania donovani antigen was evaluated for the serodiagnosis of kala‐azar in a rural setting in eastern Sudan. The performance of the FD‐DAT was compared with standard liquid antigen (LQ) by testing serum samples and blood samples collected on filter paper of microscopically and PCR‐confirmed VL patients, apparently healthy endemic controls and patients with other relevant infectious diseases for the region. In the present study, the FD‐DAT had a sensitivity of 96.8% and a specificity of 96.2%. The LQ‐DAT had a sensitivity of 91.0% and a specificity of 96.6%. A high degree of agreement (97.3%; r‐value 0.94) was observed between the FD‐DAT and the LQ‐DAT, as well as between the FD‐DAT performed on serum samples and corresponding blood samples collected on filter paper (agreement 97.8%; r‐value 0.79). The FD‐DAT is very suitable as diagnostic test for kala‐azar in remote rural conditions as it is sensitive, specific and stable. The antigen is affordable, reproducible and available, which contributes to the sustainability of the DAT as a diagnostic test for VL.
Mosquito nets and the poor: can social marketing redress inequities in access?
Authors: Nathan Rose , Masanja Honorati , Mshinda Hassan , Schellenberg Joanna A. , de Savigny Don , Lengeler Christian , Tanner Marcel , Victora Cesar G. 
Published: October 2004

SummaryTreated mosquito nets are a practical malaria control tool. However, implementation of efficient delivery mechanisms remains a challenge. We investigated whether social marketing of treated mosquito nets results in decreased equity in rural Tanzania, through household surveys before the start of a social marketing programme and 3 years later. About 12 000 household heads were asked about ownership of nets and other assets including a tin roof, radio, or bicycle. A socio‐economic status score was developed for each household. Net ownership was calculated for households in each quintile of this score, from poorest to least poor. In 1997, about 20% of the poorest households and over 60% of the least poor households owned a mosquito net. Three years later, more than half of the poorest households owned a net, as did over 90% of the least poor: the ratio of net ownership among the poorest to least poor increased from 0.3 in 1997 to 0.6 in 2000. Social marketing in the presence of an active private sector for nets was associated with increased equity.
Assessment of disease and infection of lymphatic filariasis in Northeastern Cambodia
Authors: Leang Rithea , Socheat Duong , Bin Boravong , Bunkea Tol , Odermatt Peter 
Published: October 2004

SummaryWe assessed the filariasis disease burden in four northeastern provinces of Cambodia by using and validating a key‐informant questionnaire, consisting of four questions, with pictures of patients with leg elephantiasis and hydrocoele. The questionnaire was distributed and collected through the school, health and administrative systems. Validation surveys included clinical examination, a card test for W. bancrofti (ICT Filariasis card test, AMRADTM) and night blood finger prick examination of patients reported with clinical elephantiasis. Only 48.0% of questionnaires were returned. A total of 220 patients were reported, mostly from Stung Treng (36.8%) and Rattanakiri provinces (35.0%). Key‐informants reported patients with lymphatic filariasis with a sensitivity of 85.7% for leg and 97.0% for scrotum morbidity, and with a specificity of 95.6%. However, substantial over‐reporting resulted in very low positive predictive values for elephantiasis of 19.4% for legs and of 23.7% for the scrotum. As 97.4% of patients with clinical lymphatic filariasis were older than 40 years, the diagnostic performance of the questionnaire would be improved by restricting its use to that age group. About 0.7% of 3490 W. bancrofti card tests were positive; the prevalence was 1.94% (12/618) in Rattanakiri, 0.38% (4/1055) in Stung Treng and 0.22% (2/919) in Preah Vihear. W. bancrofti microfilaria were identified in blood from two patients in Rattanakiri (0.32%) and from one patient in Stung Treng (0.09%). Brugia malayi microfilaria were identified in blood from five patients in Rattanakiri (0.81%) only. No patients with microfilariaemia were identified in Preah Vehear. In Mondulkiri province all investigations (card test, night blood examination, clinical examination) for lymphatic filariasis were negative. Our findings confirm the usefulness of key‐informant questionnaire for the identification of filariasis patients provided that high adherence can be achieved. Lymphatic filariasis infection and disease is present in northern Cambodian provinces but the burdens of disease and infection are relatively low. These results are being used in the implementation of the national control programme for lymphatic filariasis.
iNOS promoter variants and severe malaria in Ghanaian children
Authors: Cramer Jakob P. , Mockenhaupt Frank P. , Ehrhardt Stephan , Burkhardt Jana , Otchwemah Rowland N. , Dietz Ekkehardt , Gellert Sabine , Bienzle Ulrich 
Published: October 2004

SummaryNitric oxide is an important mediator in the host defence against Plasmodium falciparum malaria. It has antiparasitic effects in vitro. However, its role in clinical disease remains controversial. Polymorphisms in the inducible nitric oxide synthase promoter (iNOS; −954G→C, −1173C→T, −2.6 kb CCTTT(n) microsatellite) may influence susceptibility to and severity of malaria. We tested this hypothesis in a case–control study among Ghanaian children with severe malaria (SM) and asymptomatic parasitaemia, respectively, and in healthy controls. In this study, the respective frequencies of iNOS−954G→C and −1173C→T did not differ between groups but ≥13 microsatellite copies were associated with SM. −954G→C and −1173C→T were in linkage disequilibrium with CCTTT(8) and CCTTT(13), respectively. −954G→C/CCTTT(8) protected against hyperparasitaemia whereas −1173C→T/CCTTT(13) increased fatality. These findings suggest that iNOS promoter haplotypes rather than single nucleotide polymorphisms are associated with malaria in Ghanaian children.
Is amodiaquine failing in Rwanda? Efficacy of amodiaquine alone and combined with artesunate in children with uncomplicated malaria
Authors: Rwagacondo Claude E. , Karema Corine , Mugisha Veronique , Erhart Annette , Dujardin Jean‐Claude , Overmeir Chantal Van , Ringwald Pascal , D'Alessandro Umberto 
Published: October 2004

SummaryWe investigated the safety and efficacy of amodiaquine alone (AQ) and combined with artesunate (AQ + AS) in 308 Rwandan children 6–59 months old with uncomplicated Plasmodium falciparum malaria attending three sentinel sites. The two treatment regimes were well tolerated and no serious adverse events were recorded. After excluding new infections, children treated with AQ + AS had fewer clinical failures at day 28 after treatment than those treated with AQ alone: OR = 0.20 [95% CI: 0.06–0.57 (P = 0.001)]. Total (parasitological and clinical) failure was also significantly less frequent in the AQ + AS group: OR = 0.34 [95% CI: 0.17–0.67 (P = 0.001)]. When adjusting for study site, the hazard ratio for treatment failure was 0.37 [95% CI: 0.20–0.68 (P = 0.001)]. Combining AQ with AS increases the efficacy of the treatment but the apparent increase of AQ resistance observed in just a 1‐year period is worrying and casts doubts on the suitability of implementing AQ + AS as first‐line treatment in Rwanda. Alternative treatments should be identified and tested.
Asymmetry and Mating Success in a Periodical Cicada,Magicicada septendecim(Hemiptera: Cicadidae)
Authors: Cooley John R. 
Published: October 2004

AbstractPhenotypic symmetry results from both a genetic predisposition and the influence of the developmental environment. Although most studies of mate choice and phenotypic asymmetry are couched in terms of active choice for ‘good genes’, an alternative viewpoint is to consider incidental mating biases that arise from the functional effects of asymmetrical phenotypes. This paper (i) discusses the specific situations in which symmetry‐based mate choice may be likely, and (ii) presents research on female mate choice and symmetry in the periodical cicada,Magicicada septendecim(L.). Male mating aggregations and lack of mating gifts or parental care make this species an ideal target for studying female choice for superior mates, and thus for a relationship between male symmetry and male mating success.
Competing Females and Caring Males. Polyandry and Sex‐Role Reversal in African Black Coucals,Centropus grillii
Authors: Goymann Wolfgang , Wittenzellner Andrea , Wingfield John C. 
Published: October 2004

AbstractMost species of birds show bi‐parental or female‐only care. However, a minority of species is polyandrous and expresses male‐only care. So far, such reversals in sex roles have been demonstrated only in precocial bird species, but there was suggestive evidence that such a mating system may occur in one altricial bird species, the black coucal,Centropus grillii. In a field study in Tanzania we investigated whether black coucals are sex‐role reversed and polyandrous. We found that males were mated to one female, rarely vocalized and provided all parental care from incubation of eggs to feeding of young. In contrast, female black coucals were about 69% heavier and 39% larger than males and polyandrous. They spent a large proportion of time calling from conspicuous perches, defended breeding territories, did not help in provisioning young and had a higher potential reproductive rate than males. We conclude that the black coucal currently represents the only altricial bird species with sole male parental care and a classical polyandrous mating system. High nest predation pressure and small territory sizes due to high food abundance may have been important factors in the evolution of sex‐role reversal and polyandry in this species.
Clustering Objects on Subsets of Attributes (with Discussion)
Authors: Friedman Jerome H. , Meulman Jacqueline J. 
Published: October 2004

SummaryA new procedure is proposed for clustering attribute value data. When used in conjunction with conventional distance-based clustering algorithms this procedure encourages those algorithms to detect automatically subgroups of objects that preferentially cluster on subsets of the attribute variables rather than on all of them simultaneously. The relevant attribute subsets for each individual cluster can be different and partially (or completely) overlap with those of other clusters. Enhancements for increasing sensitivity for detecting especially low cardinality groups clustering on a small subset of variables are discussed. Applications in different domains, including gene expression arrays, are presented.
Restricted Likelihood Ratio Lack-of-Fit Tests Using Mixed Spline Models
Authors: Claeskens Gerda 
Published: October 2004

SummaryPenalized regression spline models afford a simple mixed model representation in which variance components control the degree of non-linearity in the smooth function estimates. This motivates the study of lack-of-fit tests based on the restricted maximum likelihood ratio statistic which tests whether variance components are 0 against the alternative of taking on positive values. For this one-sided testing problem a further complication is that the variance component belongs to the boundary of the parameter space under the null hypothesis. Conditions are obtained on the design of the regression spline models under which asymptotic distribution theory applies, and finite sample approximations to the asymptotic distribution are provided. Test statistics are studied for simple as well as multiple-regression models.
Merging Information for Semiparametric Density Estimation
Authors: Fokianos Konstantinos 
Published: October 2004

SummaryThe density ratio model specifies that the likelihood ratio of m−1 probability density functions with respect to the mth is of known parametric form without reference to any parametric model. We study the semiparametric inference problem that is related to the density ratio model by appealing to the methodology of empirical likelihood. The combined data from all the samples leads to more efficient kernel density estimators for the unknown distributions. We adopt variants of well-established techniques to choose the smoothing parameter for the density estimators proposed.
Estimation of Generalized Linear Latent Variable Models
Authors: Huber Philippe , Ronchetti Elvezio , Victoria-Feser Maria-Pia 
Published: October 2004

SummaryGeneralized linear latent variable models (GLLVMs), as defined by Bartholomew and Knott, enable modelling of relationships between manifest and latent variables. They extend structural equation modelling techniques, which are powerful tools in the social sciences. However, because of the complexity of the log-likelihood function of a GLLVM, an approximation such as numerical integration must be used for inference. This can limit drastically the number of variables in the model and can lead to biased estimators. We propose a new estimator for the parameters of a GLLVM, based on a Laplace approximation to the likelihood function and which can be computed even for models with a large number of variables. The new estimator can be viewed as an M-estimator, leading to readily available asymptotic properties and correct inference. A simulation study shows its excellent finite sample properties, in particular when compared with a well-established approach such as LISREL. A real data example on the measurement of wealth for the computation of multidimensional inequality is analysed to highlight the importance of the methodology.
Efficiency of Generalized Estimating Equations for Binary Responses
Authors: Rao Chaganty N. , Joe Harry 
Published: October 2004

SummaryUsing standard correlation bounds, we show that in generalized estimation equations (GEEs) the so-called ‘working correlation matrix’R(α) for analysing binary data cannot in general be the true correlation matrix of the data. Methods for estimating the correlation param-eter in current GEE software for binary responses disregard these bounds. To show that the GEE applied on binary data has high efficiency, we use a multivariate binary model so that the covariance matrix from estimating equation theory can be compared with the inverse Fisher information matrix. But R(α) should be viewed as the weight matrix, and it should not be confused with the correlation matrix of the binary responses. We also do a comparison with more general weighted estimating equations by using a matrix Cauchy–Schwarz inequality. Our analysis leads to simple rules for the choice of α in an exchangeable or autoregressive AR(1) weight matrix R(α), based on the strength of dependence between the binary variables. An example is given to illustrate the assessment of dependence and choice of α.
Approximating Hidden Gaussian Markov Random Fields
Authors: Rue Håvard , Steinsland Ingelin , Erland Sveinung 
Published: October 2004

SummaryGaussian Markov random-field (GMRF) models are frequently used in a wide variety of applications. In most cases parts of the GMRF are observed through mutually independent data; hence the full conditional of the GMRF, a hidden GMRF (HGMRF), is of interest. We are concerned with the case where the likelihood is non-Gaussian, leading to non-Gaussian HGMRF models. Several researchers have constructed block sampling Markov chain Monte Carlo schemes based on approximations of the HGMRF by a GMRF, using a second-order expansion of the log-density at or near the mode. This is possible as the GMRF approximation can be sampled exactly with a known normalizing constant. The Markov property of the GMRF approximation yields computational efficiency.The main contribution in the paper is to go beyond the GMRF approximation and to construct a class of non-Gaussian approximations which adapt automatically to the particular HGMRF that is under study. The accuracy can be tuned by intuitive parameters to nearly any precision. These non-Gaussian approximations share the same computational complexity as those which are based on GMRFs and can be sampled exactly with computable normalizing constants. We apply our approximations in spatial disease mapping and model-based geostatistical models with different likelihoods, obtain procedures for block updating and construct Metropolized independence samplers.
Real Nonparametric Regression Using Complex Wavelets
Authors: Barber Stuart , Nason Guy P. 
Published: October 2004

SummaryWavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients.
Nonparametric Inference About Service Time Distribution from Indirect Measurements
Authors: Hall Peter , Park Juhyun 
Published: October 2004

SummaryIn studies of properties of queues, for example in relation to Internet traffic, a subject that is of particular interest is the ‘shape’ of service time distribution. For example, we might wish to know whether the service time density is unimodal, suggesting that service time distribution is possibly homogeneous, or whether it is multimodal, indicating that there are two or more distinct customer populations. However, even in relatively controlled experiments we may not have access to explicit service time data. Our only information might be the durations of service time clusters, i.e. of busy periods. We wish to ‘deconvolve’ these concatenations, and to construct empirical approximations to the distribution and, particularly, the density function of service time. Explicit solutions of these problems will be suggested. In particular, a kernel-based ‘deconvolution’ estimator of service time density will be introduced, admitting conventional approaches to the choice of bandwidth.
Fish oils in the care of coronary heart disease patients: a meta‐analysis of randomized controlled trials
Authors: Yzebe Delphine , Lievre Michel 
Published: October 2004

AbstractWhat is the place of fish oils in the care of coronary heart disease (CHD) patients? As several clinical trials have already addressed this question without giving definitive answers, we did a meta‐analysis of trials regarding the efficacy of omega‐3 fatty acids in preventing cardiovascular mortality and morbidity. We searched the MEDLINE (1966–2003), EMBASE databases, proceedings abstracts and references of reviewed articles. Randomized controlled trials (RCTs) of the efficacy of omega‐3 fatty acids among adults with recent or acute myocardial infarction (MI), or angina were selected. Two reviewers abstracted data independently. Five relevant outcomes, mortality from all causes, fatal and non‐fatal MI, non‐fatal stroke and angina, were measured. Data were synthesized using a fixed effect model. Ten RCTs with 14 727 patients were included. No significant heterogeneity was detected. Daily intake of omega‐3 fatty acids for a mean duration of 37 months decreased all causes of mortality by 16% (relative risk 0.84, 95% confidence interval [0.76; 0.94]) and the incidence of death due to MI by 24% (0.76, [0.66; 0.88]). No significant effect was found for the other outcomes. Because of the suboptimal quality of the studies included into the meta‐analysis and the absence of data in patients receiving statins, these results do not justify adding fish oils systematically to the heavy pharmaceutical assortment already recommended in CHD patients.