bluuebunny/crossref_metadata_2025 huggingface dataset:
A Multi‐Model Approach for the Efficient Solution of Differential‐Algebraic Boundary Value Problems
Authors: Callies R.
Published: June 2004

A multi‐model approach is presented which allows the efficient and stable coupling between high precision algorithms for DAE boundary value problems arising from constrained optimal control problems and model data obtained with rather low accuracy from finite element solutions of PDEs. A model hierarchy with increasing approximation accuracy serves as an intermediate layer. Numerical efficiency is demonstrated for an example from flight mechanics.
Index Analysis of a Nonlinear PDAE System Describing a Molten CarbonateFuel Cell
Authors: Chudej Kurt , Petzet Verena , Scherdel Sabine , Pesch Hans Josef , Schittkowski Klaus , Heidebrecht Peter , Sundmacher Kai
Published: June 2004

Without combustion, molten carbonate fuel cells (MCFC) convert chemical energy contained in fuel and oxidizer to electric energy via electro‐chemical reaction. Performance and service life of MCFCs depends on its operating temperature. So control of the operation temperature within a specified range and reducing temperature fluctuations is highly desirable. In a very first step towards this goal prior to numerical simulations an index analysis of the partial differential‐algebraic equation system (PDAE) is given. Some numerical solutions can be found in [4].
Runge‐Kutta methods for monotone differential and stochastic equations
Authors: Kloeden Peter , Schropp Johannes
Published: June 2004

Runge‐Kutta methods which preserve monotonicity for deterministic ordinary differential equations also preserve montonicity for random differential equations albeit with reduced order. However, the only one‐step numerical methods which preserve the montone structure of a monotone stochastic differential equation are the strong Taylor schemes of strong order 0:5 and 1:0.
Uniform convergence of a finite difference scheme for a system of coupledreaction‐diffusion equations
Authors: Linss Torsten , Madden Niall
Published: June 2004

We study a system of coupled reaction‐diffusion equations. The equations have diffusion parameters of different magnitudes associated with them. Near each boundary, their solution exhibit two overlapping layers. A difference scheme on layer‐adapted piecewise uniform meshes is used to solve the system numerically. We show that the scheme is almost second‐order convergent, uniformly in both perturbation parameters, thus improving previous results [3].
Time integration of index 1 DAEs with Rosenbrock methods using Krylovsubspace techniques
Authors: Wensch J. , Podhaisky H. , Hartmann S.
Published: June 2004

The derivation of Rosenbrock‐Krylov methods for index 1 DAEs involves two well known techniques: a limit process which transforms a singular perturbed ODE to an index 1 DAE and the use of Krylov iterations instead of direct linear solvers for the stage equations. We show that our derived class of Rosenbrock‐Krylov schemes is independent of the order in which we apply these techniques. We also conclude that for convergence a rather accurate solution of the algebraic part is always needed.
Solving Multi‐Scale problems with heterogeneous finite difference methods
Authors: Abdulle Assyr
Published: June 2004

Multi‐scale differential equations are problems in which the variables can have different length scales. The direct numerical solution of differential equations with multiple scales is often difficult due to the work for resolving the smallest scale. We present here a strategy which allows the use of finite difference methods for the numerical solution of parabolic multi‐scale problems, based on a coupling of macroscopic and microscopic models for the original equation.
Evidence for acid‐induced loss of Cdx2 expression in duodenal gastric metaplasia
Authors: Faller Gerhard , Dimmler Arno , Rau Tilman , Spaderna Simone , Hlubek Falk , Jung Andreas , Kirchner Thomas , Brabletz Thomas
Published: June 2004

Gastric metaplasia in the duodenum (GMD) is characterized by transdifferentiation of intestinal epithelial cells into gastric foveolar cells within the duodenal mucosa. GMD is often associated with duodenal ulceration. Higher duodenal acidity due to increased gastric acid output into the duodenum has been implicated in the development of GMD. Intestinal development and homeostasis are controlled by the homeobox transcription factor Cdx2, which is considered to be the master regulator of intestinal differentiation. Using immunohistochemistry, the present study shows that GMD is associated with loss of expression of Cdx2 and its target gene product sucrase‐isomaltase. Quantitative RT‐PCR experiments using the intestinal cell line Caco2 revealed that Cdx2 and sucrase‐isomaltase were down‐regulated and gastric mucins MUC5AC and MUC6 were up‐regulated under acidic culture conditions. Thus, it is suggested that increased acid exposure leads to GMD by impairing the transcription of Cdx2 and subsequently that of its intestine‐specific target genes. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Expression of Sonic hedgehog pathway genes is altered in colonic neoplasia
Authors: Oniscu Anca , James Roberta M , Morris Robert G , Bader Scott , Malcomson Roger DG , Harrison David J
Published: June 2004

The Hedgehog (Hh) signalling pathway is crucial for normal development and patterning of numerous human organs including the gut. Hh proteins are also expressed during gastric gland development and gastric epithelial differentiation in adults. Recently, dysregulation of these developmentally important genes has been implicated in cancer, leading to the present study of the expression of Hh signalling proteins in colon cancer. In this study, normal colon and colonic lesions (hyperplastic polyp, adenoma, and colonic adenocarcinoma) were examined by immunohistochemistry using antibodies against Hh signalling molecules: the secreted protein Sonic hedgehog (SHH), its receptor Patched (PTCH), and the PTCH‐associated transmembrane protein Smoothened (SMOH). The study shows that Hh signalling pathway members are expressed in normal colonic epithelium. SHH was expressed at the top of the crypts and in a few basally located cells, while PTCH was detected in the neuroendocrine cells and SMOH at the brush border of superficial epithelium. RT‐PCR analysis of laser‐microdissected crypts from normal human colon confirmed that mRNAs encoding these proteins were expressed in colonic epithelium. Expression of SHH, PTCH, and SMOH was up‐regulated in hyperplastic polyps, adenomas, and adenocarcinomas of the colon, and SHH expression correlated with increased expression of the proliferation marker Ki‐67 in all lesions examined. To address whether the Hh signalling pathway is functional in the gut, the effect of Shh on epithelial cells in vitro was explored by treating primary murine colonocytes with either Shh peptide or neutralizing anti‐Shh antibody. The proportion of cells in the S‐phase was assessed by bromodeoxyuridine (BrdU) incorporation. It was found that exogenous Shh promotes cell proliferation in colonocytes, while anti‐Shh inhibits proliferation, suggesting that Shh is required during proliferation of epithelial cells in vitro. It is suggested that SHH is required during epithelial proliferation in the colon and that there is a possible role for Hh signalling in epithelial colon tumour progression in vivo. Copyright © 2004 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Adventure therapy for adolescents with cancer
Authors: Stevens Bonnie , Kagan Susan , Yamada Janet , Epstein Iris , Beamer Madelyn , Bilodeau Mario , Baruchel Sylvain
Published: June 2004

The objective of this study was to describe adolescents' with cancer experience in an adventure therapy program from a health related quality of life (HRQL) perspective. A qualitative descriptive research method was used. Eleven adolescents and five health professionals participated in a guided group adventure therapy expedition in a remote area of Canada. The expedition was videotaped and data were collected using an unstructured interview format with both adolescents and health professionals. Emerging themes were identified using a qualitative descriptive exploratory analysis. Four major themes and related sub‐themes were generated. The major themes were: developing connections, togetherness, rebuilding self‐esteem, and creating memories. Adventure therapy was viewed by the adolescents and health care professionals as a positive experience with multiple benefits. This preliminary research will contribute to an understanding of adolescents' experiences with cancer and provide a basis for future studies evaluating the impact of adventure therapy on HRQL. © 2004 Wiley‐Liss, Inc.
Patterns of distress in parents of children undergoing stem cell transplantation
Authors: Phipps Sean , Dunavant Maggi , Lensing Shelly , Rai Shesh N.
Published: June 2004

Parents (N = 151) of children undergoing bone marrow or stem cell transplantation (BMT) were assessed in a prospective, longitudinal design with repeated measures of distress (mood disturbance, perceived stress, caregiver burden). Parents were assessed weekly from admission for BMT (week‐1) through week +6 post‐BMT, followed by monthly assessments through month +6. Concurrent measures of child distress (somatic distress, mood disturbance) were also obtained by parent and child report. Parents demonstrate modest, but significant elevations in distress, particularly during the early period from admission through week +3. Elevations in parental distress are transient, and appear to be largely resolved by 4–6 months post‐BMT. Parental distress was unrelated to child age, gender, diagnosis, or type of transplant, but was significantly related to parental socioeconomic status (SES). Parents from lower SES backgrounds reported greater levels of distress throughout the BMT process. Moderate correlations were observed between measures of parent and child distress, and level of child distress at the time of admission for BMT was predictive parental distress trajectories across the acute phase of BMT. These findings point to appropriate targets for intervention to reduce transplant‐related distress. © 2004 Wiley‐Liss, Inc.
Central diabetes insipidus as presenting symptom of Langerhans cell histiocytosis
Authors: Prosch Helmut , Grois Nicole , Prayer Daniela , Waldhauser Franz , Steiner Manuel , Minkov Milen , Gadner Helmut
Published: June 2004

Background and Objectives

Central diabetes insipidus (CDI) is a rare disorder associated with various underlying diseases. Among the systemic diseases that may cause CDI, Langerhans cell histiocytosis (LCH) is the most common. Therefore, in patients with endocrinologically proven CDI, a comprehensive diagnostic evaluation is crucial to identify possible extracranial sites of LCH. The goal of the diagnostic evaluation is to yield histopathological proof of the underlying disease. If possible, this histopathological proof should be provided by a biopsy of extracranial lesions to avoid a potentially hazardous biopsy of the pituitary stalk.

Study Design

In this retrospective study we included 54 patients registered at the LCH study reference center in whom the onset of CDI preceded the diagnosis of LCH, and we investigated their presentation and course to define a clinical pattern characteristic for LCH.

Results

In 49/54 patients (91%) the detection and biopsy of extracranial lesions led to the diagnosis of LCH. The most frequently involved organs were bones, skin, and lungs; 86% of the patients with bone lesions had skull lesions. In 18% of the patients extracranial lesions were already found at presentation of CDI, in another 51% of the patients extracranial lesions were found within 1 year from onset of CDI.

Conclusions

These observations underline that a comprehensive search for extracranial lesions at presentation and during the first year thereafter may help to achieve a specific diagnosis without a pituitary stalk biopsy. © 2004 Wiley‐Liss, Inc.
Impact of location on outcome in children with low‐grade oligodendroglioma
Authors: Peters Ove , Gnekow A.K. , Rating D. , Wolff J.E.A.
Published: June 2004

Background

Childhood low‐grade oligodendroglioma (WHO grade II) are rare. No controlled pediatric study has been published, to generate high level evidence for the best treatment. Therefore, we retrospectively analyzed data available from pediatric patients.

Procedure

We pooled data from two prospective German multicentre studies (HIT‐DOK and HIT‐LGG). Eligibility criteria were: (1) primary neoplasm, (2) histology of pure oligodendroglioma WHO grade II, (3) intracranial location, (4) age <18 years, (5) date of diagnosis: 1990–2002, (6) observation time >6 months. The outcome was analyzed by using the SPSS®‐software.

Results

Nineteen boys and 13 girls were eligible (median age 10.3 years). The tumor locations included: 26 peripheral tumors (23 cerebral hemisphere, 3 cerebellum), and 6 central tumors (4 thalamus, 1 frontal mesencephalon, 1 basal ganglia). Resections were classified as complete in 18 (14 cerebral hemispheres, 3 cerebellum, 1 thalamus) and less than complete in 14 patients (3 subtotal resections, 8 partial resections, 3 biopsy). The 5‐year event‐free survival (EFS) and overall survival (OS) rates of all patients were 81.3 and 84.4%, respectively (median observation time 3.8 years). All of the 26 children with peripheral tumors were alive with no tumor progression, but five of six patients with central tumors died of disease (median time to death 1.6 years). This survival difference was statistically significant for EFS (P < 0.0001) and OS (P < 0.0001). The difference between completely resected versus incompletely resected tumors was far less striking (P > 0.06).

Conclusions

The outcome of children with centrally located low‐grade oligodendroglioma is particularly poor, while tumors of the cerebral hemispheres and cerebellum carry an excellent prognosis, even with minor tumor resection. © 2004 Wiley‐Liss, Inc.
Preparation and nonisothermal crystallization behavior of polyamide 6/montmorillonite nanocomposites
Authors: Tjong S. C. , Bao S. P
Published: June 2004

Polyamide 6 (PA6)/montmorillonite (MMT) nanocomposites were prepared via melt intercalation. The structure, mechanical properties, and nonisothermal crystallization kinetics of PA6/MMT nanocomposites were investigated by X‐ray diffraction (XRD), tensile and impact tests, and differential scanning calorimetry (DSC). Before melt compounding, MMT was treated with an organic surfactant agent. XRD traces showed that PA6 crystallizes exclusively in γ‐crystalline structure within the nanocomposites. Tensile measurements showed that the MMT additions are beneficial in improving the strength and the stiffness of PA6, at the expense of tensile ductility. Impact tests revealed that the impact strength of PA6/MMT nanocomposites tended to decrease with increasing MMT content. The nonisothermal crystallization DSC data were analyzed by Avrami, Ozawa, modified Avrami‐Ozawa, and Nedkov methods. The validity of these empirical equations on the nonisothermal crystallization process of PA6/MMT nanocomposites is discussed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2878–2891, 2004
ANSI/IEEE 1471 and systems engineering
Authors: Maier Mark W. , Emery David , Hilliard Rich
Published: June 2004

ANSI/IEEE Standard 1471‐2000 is the Recommended Practice for Architectural Description of Software‐Intensive Systems, developed by the IEEE's Architecture Working Group (AWG) under the sponsorship of the Software Engineering Standards Committee of IEEE. ANSI/IEEE 1471‐2000 is the first formal standard to address the content and organization of architectural descriptions. [A wide variety of architecture frameworks exist as de facto standards in particular communities, but ANSI/IEEE 1471 is the first formal standard in the sense of being a product formally approved by a recognized standards body.] The standard defines the structure and content of an Architectural Description (AD) and incorporates a broad consensus on best practices for such descriptions. Although ANSI/IEEE 1471‐2000 was conceived as a software‐focused standard, this article argues that it is equally applicable to any system; hence appropriate for use as a part of systems engineering to describe system architectures. This article reviews the concepts of ANSI/IEEE 1471‐2000, the rationale for their selection, and demonstrates its application in systems engineering. © 2004 Wiley Periodicals, Inc. Syst Eng 7: 257–270, 2004
Factors mediating the effect of gender on ninth‐grade Turkish students' misconceptions concerning electric circuits
Authors: Sencar Selen , Eryilmaz Ali
Published: June 2004

This study was designed to identify and analyze possible factors that mediate the effect of gender on ninth‐grade Turkish students' misconceptions concerning electric circuits. A Simple Electric Circuit Concept Test (SECCT), including items with both practical and theoretical contexts, and an Interest‐Experience Questionnaire about Electricity (IEQ) were administered to 1,678 ninth‐grade students (764 male, 914 female) after the completion of a unit on electricity to assess students' misconceptions and interests‐experiences about electricity. Results of the concept test indicated that general performances of the students were relatively low and that many students had misconceptions in interpreting electric circuits. When the data were analyzed using MANOVA and follow‐up ANOVAs, a gender difference for males was observed on the dependent variable of total scores on the 10 practical items; however, there was no significant gender difference on the dependent variable of total scores on the six theoretical items. Moreover, when the same data were analyzed using MANCOVA and follow‐up ANCOVAs, controlling students' age and interest‐experience related to electricity, the observed gender difference was mediated on the total scores on the practical items. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 603–616, 2004
Differences in cell migration of cultured pituitary cells from infantile and adult rats: participation of the extracellular matrix and epidermal growth factor
Authors: González Balby , Solano‐Agama Ma.del Carmen , González del Pliego Margarita , Mendoza‐Garrido Ma.Eugenia
Published: June 2004

During early postnatal development in the rat, the tissue architecture of the pituitary gland shows changes, revealing an intense migration process of the cells. The aim of this work was to examine anterior pituitary cell migration over type I and III collagen as well as type IV collagen, of cultured pituitary cells from infantile rats and adult rats, and the participation of the epidermal growth factor in this process. Differences in cell migration rate over these two types of collagen substrates were observed at both ages, and all in all, three times more cells migrated over type I/III collagen than over type IV collagen. These data show the migration‐promoting role of type I/III collagen for pituitary cells. Furthermore, when infantile cells were challenged to migrate over bovine serum albumin, the migration rate diminished, and, on the contrary, adult cell migration was higher. However, over collagen, infantile cells increased their migration rate with epidermal growth factor stimulation and adult cells showed a decrease in migration when the growth factor was in the medium. During migration, pituitary cells associated and arranged in clusters. This behavior increased in the presence of epidermal growth factor in the infantile cultures. Moreover, epidermal growth‐factor‐stimulated infantile cells formed larger aggregates. Adult cells also showed associative behavior, but more cells were observed isolated than in cluster arrangements and the growth factor did not induce changes in this behavior. Results showed a difference in the response of cell migration and cell association capacity to epidermal growth factor after migration of infantile and adult pituitary cells. With these observations we propose that epidermal growth factor is a cell regulator of the pituitary tissue re‐arrangement process during the infantile period.
Endometrial thickness after misoprostol use for early pregnancy failure
Authors: Creinin M.D , Harwood B , Guido R.S , Fox M.C , Zhang J ,   for the NICHD Management of Early Pregnancy Failure Trial
Published: June 2004

Objectives: To assess if there was any potential relationship between endometrial thickness and final treatment outcome in women successfully treated with misoprostol for a first trimester anembryonic gestation, embryonic demise or fetal demise. Methods: Eighty women were treated with up to two doses of misoprostol 800 μg vaginally for early pregnancy failure. Subjects were scheduled to return 2 (range 1–4), 7 (range 5–9) and 14 (range 12–17) days after treatment. Transvaginal ultrasonography was performed at each follow‐up visit. Results: The median endometrial thickness at each of the follow‐up visits for women who had expelled the gestational sac was 14 mm, 10 mm, and 7 mm, respectively. The endometrial thickness at the first follow‐up visit exceeded 15 mm in 20 subjects (36%) and 30 mm in four subjects (7%). Only three women had a suction aspiration for bleeding after documented expulsion. The endometrial thickness for these women was 11, 13, and 14 mm at the first follow‐up visit. Conclusions: There is no obvious relationship between increasing endometrial thickness and the need for surgical intervention in women treated with misoprostol for early pregnancy failure.
The evolution of a quality of care approach for improving emergency obstetric care in rural hospitals in Nepal
Authors: Clapham S , Basnet I , Pathak L.R , McCall M
Published: June 2004

We describe the iterative process of developing a locally‐appropriate quality of care approach and its role in emergency obstetric care (EmOC) programming in Nepal. We describe the context of maternal health issues in Nepal, the rationale for developing a quality of care approach within a model to improve EmOC, and outline the outcomes and catalytic effects of the process. The lessons learned during the development of this approach are detailed. The program developed and implemented a quality of care approach at three district hospitals in Nepal. This resulted in improvements in the structure, process and outcomes of EmOC in these institutions. The process also resulted in improved understanding of quality of care approaches on both local and national levels and the creation of a Nepalese quality of care evaluation framework for maternity services. While the theoretical concept of quality of care is difficult to translate into a concrete approach, we used a process in rural hospitals in Nepal that created highly motivated teams and improved the overall functioning of these hospitals.
Evolution of the postabortion care program in Nepal: the contribution of a national Safe Motherhood Project
Authors: Basnet I. , Clapham S. , Shakya G. , McCall M.
Published: June 2004

The objective of this review is to present the findings and lessons learned over the first 4 years (1999–2002) of implementation of postabortion care (PAC) services outside of major urban centers in Nepal, where a significant proportion of services are provided by nurses. The contributions made by a national Safe Motherhood project to the establishment of the National Postabortion Care Program including the promotion of nurse providers within an integrated program of emergency obstetric care services are highlighted. Clinical competency assessments and service utilization data from three district hospital‐based postabortion service sites supported by the Nepal Safer Motherhood Project are analyzed. The relationship between the findings of this assessment and two previous assessments, one covering two districts and one nationwide, are discussed. This review found that nurses are at least as competent as physicians in providing postabortion care services. The inclusion of postabortion care into the emergency treatment of obstetric complications provided the environment needed for successful introduction of nurse‐led PAC services. Competency‐based training of nurse providers is the key to making life‐saving postabortion care services accessible and affordable in Nepal. Ensuring that these nurse providers are able to implement services requires strategic planning, careful advocacy and support from physician colleagues as well as the presence of adequate infrastructure and equipment. The successful introduction of postabortion care services into three district hospitals also offering emergency obstetric care provides an example of how a nurse‐led service can be integrated into an emergency obstetric care support project. The project's learning has influenced national policy on the expansion of the postabortion care program throughout Nepal.
Safe abortion: WHO technical and policy guidance
Authors: Cook R.J , Dickens B.M , Horga M
Published: June 2004

In 2003, the World Health Organization published its well referenced handbook Safe Abortion: Technical and Policy Guidance for Health Systems to address the estimated almost 20 million induced abortions each year that are unsafe, imposing a burden of approximately 67 thousand deaths annually. It is a global injustice that 95% of unsafe abortions occur in developing countries. The focus of guidance is on abortion procedures that are lawful within the countries in which they occur, noting that in almost all countries, the law permits abortion to save a woman's life. The guidance treats unsafe abortion as a public health challenge, and responds to the problem through strategies concerning improved clinical care for women undergoing procedures, and the appropriate placement of necessary services. Legal and policy considerations are explored, and annexes present guidance to further reading, international consensus documents on safe abortion, and on manual vacuum aspiration and post‐abortion contraception.
Neonatal outcome in discordant eutrophic twins
Authors: Smiljan Severinski N , Mamula O , Petrovic O
Published: June 2004

Objective: To compare maternal characteristics and neonatal outcome in discordant twin gestations (DT) and concordant twin gestation (CT). Method: Maternal and neonatal data base of live twins >25 weeks’ gestation (N=351 pairs) were reviewed for antepartum complications, labor beginning, mode of delivery, neonatal complications, malformations and perinatal mortality. The chi‐squared analysis and Student t‐tests were used to analyze the differences between discordant and concordant premature and term twin pairs, and appropriate for gestational age (AGA) twins, separately. Results: DT occurred in 15.1% of all twin pregnancies. In preterm and term DT there were significantly more elective cesareans. Growth discordance among preterm and term eutrophic twins was not connected with increased neonatal death or other complications, except higher incidence of early neurological signs in term DT. Conclusion: We strongly believed that prematurity and not discordant growth of eutrophic twins has important influence on neonatal outcome.
Risk factors for preterm birth in Vietnam
Authors: Nguyen N , Savitz D.A , Thorp J.M
Published: June 2004

Objective: To identify the risk of preterm birth and possible determinants among women in Hanoi, Vietnam. Method: Prospective cohort study of 1709 women with singleton live births at Hanoi Obstetrics and Gynecology Hospital, Hanoi, Vietnam, June–October 2002. Logistic regression analysis was used to examine predictors of preterm birth (<37 weeks’ gestation). Result: The risk of preterm birth was 11.8%. Physically demanding work during pregnancy, two or more prior spontaneous abortions, history of preterm birth, vaginal bleeding, inadequate prenatal care during the first 20 weeks of gestation, and history of intrauterine device use with removal less than 12 months before the current pregnancy were associated with increased risk of preterm birth (adjusted odds ratios between 1.8 and 2.6). Conclusion: Preterm birth is relatively frequent in this population. Beyond established risk factors, these data implicated agricultural work and physical work demands with preterm birth, as well as history of recent IUD use.
Cysteine proteinase activity is required for survival of the parasite in experimental acute amoebic liver abscesses in hamsters
Authors: OLIVOS-GARCÍA A. , TELLO E. , NEQUIZ-AVENDAÑO M. , GONZÁLEZ-CANTO A. , LÓPEZ-VANCELL R. , DE LEÓN M. C. GARCÍA , MONTFORT I. , PÉREZ-TAMAYO R.
Published: June 2004

Axenic trophozoites ofEntamoeba histolyticastrain HM1-IMSS grownin vitroin the presence of E-64, a potent irreversible inhibitor of cysteine proteinases, preserved their viability, their rate of replication, their resistance to complement, their haemolytic capacity and their ability to destroy target cells, despite complete inhibition of total cysteine proteinase activity. On the other hand, their erythrophagocytic capacity and their ability to decrease TER of MDCK cells was partially decreased. The same trophozoites injected into the portal vein of hamsters receiving a maintaining dose of E-64 failed to cause tissue damage and were rapidly eliminated. Our results suggest that amoebic cysteine proteinase activity is not required for amoebic functions inin vitroconditions, but that it becomes necessary for survival of trophozoites inin vivoconditions, whatever other role (if any) it may play in the parasite's virulence.
The persistence of componentTheileria parvastocks in cattle immunized with the ‘Muguga cocktail’ live vaccine against East Coast fever in Uganda
Authors: OURA C. A. L. , BISHOP R. , WAMPANDE E. M. , LUBEGA G. W. , TAIT A.
Published: June 2004

The ‘Muguga cocktail’ live vaccine comprises threeTheileria parvastocks (Muguga, Kiambu 5 and the buffalo-derived Serengeti-transformed) and has been used extensively in Eastern, Central and Southern Africa with an infection and treatment protocol to protect cattle against East Coast fever. We report the characterization of the three component vaccine stocks using a panel of polymorphic micro-satellite and mini-satellite markers and the development of a stock-derived PCR method that distinguishes two of the vaccine stocks. These markers, with the use of a recently developed Reverse Line Blot assay, have enabled us to address four important questions in relation to vaccination. First, how closely related are the vaccine stocks, secondly do all three stocks persist post-vaccination and induce a carrier state, thirdly is there evidence for the transmission of the vaccine stocks and fourthly does vaccination prevent infection with local genotypes? The results show that Muguga and Serengeti-transformed stocks are highly related but very distinct from Kiambu 5 that persists in vaccinated cattle establishing a carrier state. No evidence was obtained for the transmission of vaccine stocks to co-grazed animals, although these animals were infected with up to 8 differentT. parvagenotypes showing there was a significant level of tick challenge. Some of the vaccinated animals become infected with a subset of local genotypes providing evidence for limited vaccine ‘breakthrough’.
An experimental field approach to parasitism and immune defence in voles
Authors: SCHWARZENBACH G. A. , HEGGLIN D. , STIEGER C. , DEPLAZES P. , WARD P. I.
Published: June 2004

The fox tapewormEchinococcus multilocularisis typically perpetuated in a cycle with red foxes as definitive hosts and various rodent species as intermediate hosts. In this study, foxes were baited with a highly efficient drug against cestodes (praziquantel) in 5 blocks of 1 km2. Voles,Arvicola terrestris, the most abundant intermediate host species, were trapped in the 5 baited blocks and in 5 non-baited control blocks. Baiting the foxes reduced the prevalence ofE. multilocularisin fox faecal samples in the baited blocks, but voles trapped in the two blocks did not differ in their infection rates. However, voles from the baited blocks had significantly smaller spleen masses and were more likely to be infested with mites than those from the control blocks, possibly reflecting different immunological activities. Our study suggests that the environmental contamination withE. multiloculariseggs, and perhaps those of other tapeworms, influences the immune system of the intermediate host speciesA. terrestrisin the wild.
Vector survival and parasite infection: the effect of Wuchereria bancrofti on its vector Culex quinquefasciatus
Authors: KRISHNAMOORTHY K. , SUBRAMANIAN S. , VAN OORTMARSSEN G. J. , HABBEMA J. D. F. , DAS P. K.
Published: June 2004

This paper investigates a cohort of 2187 laboratory reared Culex quinquefasciatus fed on 69 human volunteers, including 59 persons with different levels of Wuchereria bancrofti microfilariae and 10 without microfilaria. Mosquitoes were followed until death. Mosquito survival was analysed in relation to the level of microfilaria in the human and larval count in the dead mosquito. Vector mortality during the extrinsic incubation period (12 days post-engorgement) was significantly higher in mosquitoes fed on microfilaraemic volunteers (50%) than in those fed on amicrofilaraemics (29%). Both the percentage infected and the geometric mean parasite density was significantly higher among mosquitoes which died before 13 days (45% infected and 10 larvae per infected mosquito) than those surviving beyond 13 days (39% and 2·2), suggesting a parasite loss of more than 80% during the extrinsic incubation period. A large proportion (62%) of the mosquitoes that died during the early of phase of parasite development were infected (36% in low, 26% in medium and 90% in high human Mf-density). Survival analysis showed that the parasite load in mosquitoes and the human Mf-density for a given parasite load are independent risk factors of vector survival. Overall, the hazard of dying was found to be 11–15 times higher among mosquitoes fed on microfilaraemic volunteers than those fed on amicrofilaraemics. The hazard doubles for every increase of about 60–70 parasites in the vector. As a consequence of the parasite-induced reduction in vector survival, the transmission success of the parasite is reduced. The implication of the results on control/elimination of lymphatic filariasis using mass-drug administration is discussed.
Size versus health as a cue for host choice: a test of the tasty chick hypothesis
Authors: VALERA F. , HOI H. , DAROLOVÁ A. , KRISTOFIK J.
Published: June 2004

Knowledge about how parasites choose their hosts is scarce and incomplete. Recent work has primarily focused on host health (i.e. immunocompetence) whereas ecological factors have been largely neglected. Here we investigate whether the immunocompetence, the nutritional condition or body size of nestling European bee-eatersMerops apiasterare used as parameters for habitat choice of the haematophagous flyCarnus hemapterus. We found that (i) flies consistently and non-randomly preferred larger nestlings, even after controlling for differences in habitat availability (host surface), (ii) in the presence of similar-sized hosts, parasites' choice for an individual was less likely than if hosts differed in size, (iii) the more the hosts differed in size, the more the parasites aggregated on the larger nestling and (iv) parasites changed their preference according to size criteria regardless of the identity of the larger host. Neither immunocompetence nor host body condition could account for parasites' preference. Our results do not support the prediction of the Tasty Chick Hypothesis, namely that the poor immunocompetence ability of junior chicks makes them more attractive to parasites. We conclude that basic ecological factors (e.g. body size) can be essential for parasites when choosing a host.
ATP diphosphohydrolase fromSchistosoma mansoniegg: characterization and immunocytochemical localization of a new antigen
Authors: FARIA-PINTO P. , MEIRELLES M. N. L. , LENZI H. L. , MOTA E. M. , PENIDO M. L. O. , COELHO P. M. Z. , VASCONCELOS E. G.
Published: June 2004

The fact that theSchistosoma mansoniegg has two ATP diphosphohydrolase (EC 3.6.1.5) isoforms with different net charges and an identical molecular weight of 63000, identified by non-denaturing polyacrylamide gel electrophoresis and immunological cross-reactivity with potato apyrase antibodies, is shown. In soluble egg antigen (SEA), only the isoform with the lower net negative charge was detected and seemed to be the predominant species in this preparation. By confocal fluorescence microscopy, using anti-potato apyrase antibodies, theS. mansoniegg ATP diphosphohydrolase was detected on the external surface of miracidium and in von Lichtenberg's envelope. Intense fluorescence was also seen in the outer side of the egg-shell, entrapped by the surface microspines, suggesting that a soluble isoform is secreted. ATP diphosphohydrolase antigenicity was tested using the vegetable protein as antigen. The purified potato apyrase was recognized in Western blots by antibodies present in sera from experimentallyS. mansoni-infected mice. In addition, high levels of IgG anti-ATP diphosphohydrolase antibodies were detected by ELISA in the same sera. This work represents the first demonstration of antigenic properties ofS. mansoniATP diphosphohydrolase and immunological cross-reactivity between potato apyrase and sera from infected individuals.
Copro-antigen capture ELISA for the detection ofTeladorsagia(Ostertagia)circumcinctain sheep: improvement of specificity by heat treatment
Authors: JOHNSON D. A. , BEHNKE J. M. , COLES G. C.
Published: June 2004

A copro-antigen capture ELISA for the detection ofTeladorsagia circumcinctainfection in sheep was developed and evaluated. Experiments with faeces from worm-free sheep, that had been spiked with known concentrations of excretory–secretory (E–S) antigen indicated that a positive signal was generated with 180 ng of E–S/ml. A nested design, based on 8 infected and 8 worm-free sheep, was employed to assess the stages during sample preparation contributing to variation in signal from the assay. This showed that 87% of the variance in the optical density readings (ODs) was directly explained by infection status. Variation between individual sheep within infection groups, and between samples at various stages in the assay, collectively accounted for the remaining variance. Initial evaluation of specificity using faeces from animals carrying a range of monospecific infections indicated cross-reactivity withHaemonchus contortusandNematodirus spathiger. However, by treating the supernatant from faeces for 20 min at 100 °C, the cross-reactive signal was eliminated whilst the specific signal was largely preserved. Heat treatment of faeces from 12 non-infected sheep, 12 sheep withT. circumcinctaand 6 withH. contortusresulted in sensitivity being increased from 66·7 to 85·7%, and specificity from 62·5 to 87·5%. OD values showed a significant positive relationship with adult worm burdens, although at low infection intensities there was some overlap between infected and worm-free animals. We discuss the application of CC-ELISAs in facilitating selective chemotherapy of sheep, as a means of avoiding the development of anthelmintic resistance in pastoral regions where sheep are farmed on a large scale.
In vitroeffects of three woody plant and sainfoin extracts on 3rd-stage larvae and adult worms of three gastrointestinal nematodes
Authors: PAOLINI V. , FOURASTE I. , HOSTE H.
Published: June 2004

Most studies on the effects of tanniferous plants on nematodes have examined forages but have neglected the woody plants. Therefore,in vitroeffects of extracts from 3 woody plants (Rubus fructicosus,Quercus robur,Corylus avellana) have been tested on trichostrongyles and compared to sainfoin, a legume forage. Because somein vivoresults indicated that the effects of tannins differed depending on the parasitic species and/or stages, the effects were measured on 3rd-stage larvae (L3) and adult worms ofTeladorsagia circumcincta,Haemonchus contortusandTrichostrongylus colubriformis. The effects of plant extracts varied according to the plant sources, the parasite species and stages. For the woody plants, significant inhibitory effects were obtained on both stages of abomasal species. Results forT. colubriformiswere more variable. Effects of sainfoin extracts were significant onT. colubriformisandH. contortusL3, and on abomasal adult worms. In order to assess the implications of tannins, polyethylene glycol (PEG), an inhibitor of tannins, was added to hazel tree, oak and sainfoin extracts. Without PEG, significant inhibitory effects on L3 and adult worms were confirmed. After addition of PEG, the larval migration and motility of adult worms were restored in most cases. These results confirm variations in effects depending on factors related to plants or parasites and suggest that tannins are partly responsible for the effects.
Characterization of a mitochondrion-like organelle inCryptosporidium parvum
Authors: PUTIGNANI L. , TAIT A. , SMITH H. V. , HORNER D. , TOVAR J. , TETLEY L. , WASTLING J. M.
Published: June 2004

Cryptosporidium parvumis a protozoan parasite that causes widespread diarrhoeal disease in humans and other animals and is responsible for large waterborne outbreaks of cryptosporidiosis. Unlike many organisms belonging to the phylum Apicomplexa, such asPlasmodiumspp. andToxoplasma gondii, there is no clinically proven drug treatment against this parasite. Aspects of the basic biology ofC. parvumremain poorly understood, including a detailed knowledge of key metabolic pathways, its genome organization and organellar complement. Previous studies have proposed thatC. parvumlacks a relic plastid organelle, or ‘apicoplast’, but that it may possess a mitochondrion. Here we characterize a mitochondrion-like organelle inC. parvumby (i) ultrastructural and morphological description (ii) localization of heterologous mitochondrial chaperonin antibody probes (iii) phylogenetic analysis of genes encoding mitochondrial transport proteins (iv) identification and analysis of mitochondrion-associated gene sequences. Our descriptive morphological analysis was performed by energy-filtering transmission electron microscopy (EFTEM) ofC. hominisandC. parvum. The ‘mitochondrion-like’ organelle was characterized by labelling the structure with a heterologous mitochondrial chaperonin probe (hsp60) both in immunoelectron microscopy (IMEM) and immunofluorescence (IMF). Phylogenetic analysis of the mitochondrial import system and housekeeping components (hsp60 and hsp70-dnaK) suggested that theC. parvummitochondrion-like organelle is likely to have descended from a common ancestral apicomplexan mitochondrion. We also identified a partial cDNA sequence coding for an alternative oxidase (AOX) gene, a component of the electron transport chain which can act as an alternative to the terminal mitochondrial respiratory complexes III and IV, which has not yet been reported in any other member of this phylum. Degenerate primers developed to identify selected mitochondrial genes failed to identify either cytochrome oxidase subunit I, or cytochrome b. Taken together, our data aim to provide new insights into the characterization of thisCryptosporidiumorganelle and a logical framework for future functional investigation.
Patterns of cercarial production fromDiplostomum spathaceum: terminal investment or bet hedging?
Authors: KARVONEN A. , KIRSI S. , HUDSON P. J. , VALTONEN E. T.
Published: June 2004

In the production of the infective cercariae of trematodes, the terminal investment hypothesis of life-history theory predicts that the rate of host exploitation and cercarial production should increase during the period of cercarial shedding since the reproductive value of the parasite decreases during this period. In contrast, a bet hedging hypothesis that focuses on the success of transmission when host contact rate is variable predicts that cercarial production should decrease in an attempt to keep the host alive for longer and thus would increase the probability of successful transmission. We examined these two hypotheses under laboratory conditions and recorded the production ofDiplostomum spathaceumcercariae from naturally infected snail hosts,Lymnaea stagnalis. The average number of cercariae produced per day decreased as the snail host approached death counter to the terminal investment hypothesis. The finding supports the prediction of the bet hedging hypothesis and implies that the pattern of cercarial production may be explained by reduced virulence of the parasite within the snails to ensure extended total production time of cercariae. Nevertheless, survival of infected snails was still lower than uninfected snails suggesting that ultimately the infection still increased snail mortality rate. Cercarial production varied between days but was not cyclic, probably because of the physiology of the sporocysts within snails. Fewer cercariae were released at night, which may increase transmission efficiency to diurnally-active fish hosts. The mechanisms associated with daily cercarial production are discussed.
Home range and movements of the quokka Setonix brachyurus (Macropodidae: Marsupialia), and its impact on the viability of the metapopulation on the Australian mainland
Authors: Hayward Matt W. , de Tores Paul J. , Augee Michael L. , Fox Barry J. , Banks Peter B.
Published: June 2004

The home range and movements of the quokka Setonix brachyurus, a medium‐sized macropodid marsupial, were investigated using radio telemetry. Fifty‐eight quokkas from five remnant mainland populations in the northern jarrah (Eucalyptus marginata) forest of Western Australia were radio‐collared and monitored for up to 2 years between 1998 and 2000. Mean (±se) home‐range sizes were 6.39±0.77 ha and core ranges averaged 1.21±0.12 ha. Male core home ranges were larger than those of females although not when corrected for body mass. Nocturnal ranges were larger than diurnal owing to nocturnal departures from the swamp. Ranges shifted to the edge of swamps in winter, as the swamps became inundated following rain, and toward the centre in autumn as the swamps dried. Quokka populations are thought to exist below carrying capacity at all sites and this probably caused the lack of dispersal observed in this study. We hypothesize that predation is suppressing population booms which would otherwise drive dispersal and thereby maintain metapopulation dynamics. Without dispersal to rescue unpopulated patches, we conclude that the original quokka metapopulation has collapsed and ameliatory measures are required.