bluuebunny/crossref_metadata_2025 huggingface dataset:
Does Subchondral Bone Affect the Fate of Osteochondral Allografts during Storage?
Authors: Pennock Andrew T. , Robertson Catherine M. , Wagner Ferdinand , Harwood Frederick L. , Bugbee William D. , Amiel David
Published: December 2005

Background

Osteochondral allografts currently are hypothermically stored for a minimum of 14 days to a maximum of 28 days before surgical implantation, making storage conditions increasingly important. Previous studies have suggested that graft deterioration during storage may result from degradative factors and residual marrow elements in the subchondral bone.

Hypothesis

Allografts stored with large bone-to-cartilage ratios will be compromised after prolonged storage compared with grafts with minimal bone.

Study Design

Controlled laboratory study.

Methods

Osteochondral plugs were harvested from 16 fresh human femoral condyles and randomly assigned to 1 of 3 groups based on bone-to-cartilage ratios: 1:1, 5:1, or 10:1. These ratios were considered on the basis that the 1:1 ratio is the minimum bone necessary to press-fit an allograft and 10:1 is the present ratio used by tissue banks for allograft storage. After 14 and 28 days of storage at 4 ° C, the specimens were assessed for viability and viable cell density using confocal microscopy, proteoglycan synthesis by 35SO4 incorporation, and glycosaminoglycan content.

Results

All grafts underwent a significant decline in viable cell density, proteoglycan synthesis, and chondrocyte viability (particularly in the superficial region) after 14 days of storage, but no differences were observed between the 1:1, 5:1, or 10:1 ratio groups at either day 14 or day 28. In addition, no significant difference was noted in the glycosaminoglycan content in any of the groups.

Conclusion

Osteochondral allografts stored with a 10:1 bone-to-cartilage ratio, similar to tissue-banking ratios, performed no worse than allografts stored with minimal bone, suggesting that the bone-to-cartilage ratio plays little to no role in the degradation of allografts during prolonged storage.

Clinical Relevance

As the practice of osteochondral allograft resurfacing becomes more commonplace, it is important that surgeons understand the factors that affect graft quality.
Maturation Leads to Gender Differences in Landing Force and Vertical Jump Performance
Authors: Quatman Carmen E. , Ford Kevin R. , Myer Gregory D. , Hewett Timothy E.
Published: December 2005

Background

Female athletes have increased risk of anterior cruciate ligament rupture after the onset of puberty.

Hypotheses

Male athletes would demonstrate a longitudinal increase in vertical jump height compared with female athletes. There would be longitudinal gender differences in ground-reaction forces and loading rates.

Study Design

Cohort study; Level of evidence, 2.

Methods

Sixteen female and 17 male adolescent athletes were evaluated for 2 consecutive years. Subjects were included if they were classified as pubertal during the first year of testing and postpubertal during the second year. As subjects performed a drop vertical jump, ground-reaction force, and vertical jump height were measured. Data analysis consisted of a mixed design analysis of variance with post hoc analysis (paired t tests).

Results

The male athletes demonstrated increased vertical jump height with maturation (P < .001); female athletes did not. Boys significantly reduced their landing ground-reaction force (P = .005), whereas girls did not. Takeoff force decreased in girls (P = .003) but not in boys. Both boys and girls had decreased loading rates with maturation (P < .001); however, girls had higher loading rates than did boys at both stages of maturation (P = .037).

Conclusion

Male athletes demonstrated a neuromuscular spurt as evidenced by increased vertical jump height and increased ability to attenuate landing force. The absence of similar adaptations in female athletes may be related to the increased risk of anterior cruciate ligament injury.
Kinematics of the Posterior Cruciate Ligament/Posterolateral Corner-Injured Knee after Reconstruction by Single- and Double-Bundle Intra-articular Grafts
Authors: Wiley William B. , Askew Michael J. , Melby Arne , Noe Donald A.
Published: December 2005

Background

Single- and double-bundle reconstructions have been proposed for the knee after combined posterior cruciate ligament/posterolateral corner injuries.

Hypothesis

The double-bundle posterior cruciate ligament reconstruction is superior to the single-bundle posterior cruciate ligament reconstruction with regard to restoration of normal knee kinematics to the posterior cruciate ligament/posterolateral corner-sectioned knee.

Study Design

Controlled laboratory study.

Methods

Kinematics of 8 fresh-frozen, cadaveric human knees were determined in the following conditions: intact, sectioned posterior cruciate ligament/posterolateral corner, single anterolateral bundle posterior cruciate reconstruction, and double-bundle posterior cruciate reconstruction.

Results

The sectioned knee demonstrated a posterior shift of the tibial neutral position and the abnormal posterior, varus, and external rotation laxities used clinically to define a combined posterior cruciate ligament/posterolateral corner injury. Both reconstructions restored the posterior laxity to levels that were not statistically different from those seen in the intact knee, but the double-bundle reconstruction more closely mimicked the posterior laxity profile of the intact knee, having statistically lower posterior laxities than did the single-bundle reconstruction at 30°, 60°, and 90° of flexion (P < .05, analysis of variance, HSD test). The resting position of the tibia after double-bundle reconstruction trended to be anteriorly subluxated relative to its position for the intact knee at flexion angles of 30° and greater (P < .05, paired t test). Neither technique corrected the abnormal varus or external rotation laxities.

Conclusion

With either single- or double-bundle reconstructions, additional posterolateral reconstruction is recommended to correct the external rotation laxity.

Clinical Relevance

Knowledge of the kinematics of the combined posterior cruciate ligament/posterolateral corner-injured knee is important in the proper diagnosis of the injury and in the selection of the appropriate surgical reconstruction.
Is it Safe to Walk?1 Neighborhood Safety and Security Considerations and Their Effects on Walking
Authors: Loukaitou-Sideris Anastasia
Published: December 2005

The importance of walking and physical activity as determinants of good health has been well established in the medical and public health literature, but a significant number of Americans live sedentary lifestyles. Aplethora of variables lie behind an individual’s decision to walk, cycle, or exercise. This article focuses on a particular environmental variable, the safety of neighborhood surroundings, and explores how it is influencing physical activity. It integrates literatures from public health, criminology, and planning to identify, qualify, and evaluate the link between safety and security considerations and physical activity. It then proceeds to place safety and security concerns within a spatial context and to examine design and policy interventions that can help create environments more amenable to walking.
Design That Enables Diversity: The Complications of a Planning Ideal
Authors: Talen Emily
Published: December 2005

This article reviews the literature on place diversity and the quest to use design to promote social and economic mix in human settlements. The article fits together a large literature on the subject of the interrelationship between diversity and place and explores how diversity could be enabled within the context of the city-planning profession. It argues that the linkage between city planning—defined in its traditional sense as a profession concerned with the design of cities—and place diversity is understudied. Four distinct though interrelated theoretical bases for diversity are discussed: place vitality, economic health, social equity, and sustainability. The article argues that the promotion of place diversity requires focused effort on the part of planners, and that design-based strategies are an appropriate part of that effort.
Magnetization Transfer Imaging in Multiple Sclerosis
Authors: Horsfield Mark A.
Published: December 2005

Magnetization transfer (MT) is a relatively new way of generating contrast in magnetic resonance (MR) images that is sensitive to the density of the macromolecules found throughout tissue structures such as membranes, myelin, and organelles. MT imaging (MTI) can provide a quantitative measure of macromolecular density, and therefore of tissue damage, and has been applied in the central nervous system in multiple sclerosis (MS) and other diseases. This article introduces the contrast mechanisms behind MTI and gives some practical guidance about implementing MTI and about quantitative analysis of the MT scans. An overview of MT measurements made in animal studies, in postmortem tissue samples, and in other demyelinating diseases attempts to rationalize the pathological basis of changes in MT contrast in MS. The application of MTI to MS is reviewed, with emphasis on the contribution that MTI has made to the current understanding of the MS disease process, both its natural history and the response to treatment. The pathological basis of abnormal MT contrast is still open to debate, with many conflicting reports; indeed, it is unlikely that a simple measure of MT effect will reveal the details of pathology that is a combination of inflammation, demyelination, remyelination, and axonal loss. There is no doubt, however, that MT measurements have contributed to the current understanding of both disease progression and the response to treatment and will prove to be a valuable tool in the future, particularly if more refined techniques can be applied practically in multicenter studies.
Magnetic Resonance Imaging Monitoring of Multiple Sclerosis Lesion Evolution
Authors: Inglese Matilde , Grossman Robert I. , Filippi Massimo
Published: December 2005

The characteristic feature of multiple sclerosis (MS) pathology is the demyelinated plaque distributed throughout the central nervous system. Although MS is a primary demyelinating disease, acute axonal injury is common in actively demyelinating MS lesions and it is considered one of the major determinants of neurological deficit. Magnetic resonance imaging (MRI) has had a dramatic impact on MS in both the clinical practice and basic science settings. Techniques such as T2‐weighted and gadolinium‐enhanced T1‐weighted MRI are very sensitive in detecting lesions and, thus, increase the level of certainty of MS diagnosis. Conventional MRI has also improved our understanding of the pathogenesis of the disease and has provided objective and reliable measures to monitor the effect of experimental treatments in clinical trials. However, conventional MR‘I does not provide specific information on the heterogeneous pathologic substrate of MS lesions. Advanced MRI techniques, such as magnetization transfer imaging, diffusion tensor imaging, and proton MR spectroscopy, offer the unprecedented ability to observe and quantify pathological changes in lesions and normal‐appearing brain tissue over time. The present review will discuss the major contributions of conventional MRI and quantitative MRI techniques to understand how individual MS lesions evolve.
Clinical–Magnetic Resonance Imaging Correlations in Multiple Sclerosis
Authors: Zivadinov Robert , Leist Thomas P.
Published: December 2005

Conventional magnetic resonance imaging (MRI) has routinely been used to improve the accuracy of multiple sclerosis (MS) diagnosis and monitoring, detect the effects of diseasemodifying therapy, and refine the utility of clinical assessments. However, conventional MRI measures, such as the use of lesion volume and count of gadolinium‐enhancing and T2 lesions, have insufficient sensitivity and specificity to reveal the true degree of pathological changes occurring in MS. Newer metrics of MRI analysis, including T1‐weighted hypointense lesions (black holes) and central nervous system (CNS) atrophy measures, are able to capture a more global picture of the range of tissue alterations caused by inflammation, demyelination, axonal loss, and neurodegeneration. There is mounting evidence that these MRI measures correlate well with existing and developing neurological impairment and disability. In so doing, these MRI techniques can help elucidate the mechanisms underlying the pathophysiology and natural history of MS. The current understanding is that T1 black holes and CNS atrophy more accurately reflect the neurodegenerative and destructive components of the MS disease process. Therefore, the shortand long‐term studies that aim to measure the degree and severity of the neurodegenerative MS disease process should incorporate these MRI metrics as part of their standard routine MRI protocols.
Spinal Cord Imaging in Multiple Sclerosis
Authors: Tench Christopher R. , Morgan Paul S. , Jaspan Timothy , Auer Dorothee P. , Constantinescu Cris S.
Published: December 2005

Multiple sclerosis (MS) is a chronic neurological condition characterized pathologically by axonal loss, demyelination, inflammation, and gliosis. Magnetic resonance imaging (MRI) has had a major impact on diagnosing MS, understanding the condition, and monitoring the effects of treatments. Recently, spinal cord MRI has received increased attention. Advanced techniques have been used to image the spinal cord, particularly the cervical cord, and measure quantitative parameters such as T1 relaxation time, magnetization transfer ratio, and diffusivity. These metrics show central nervous system abnormalities in MS patients and various correlations with disability and might reflect specific pathological processes. Image analysis techniques have also been developed and combined with highresolution MRI to measure the cord cross‐sectional area (CSA), a metric that relates to cord atrophy. The cord CSA is reduced in MS patients compared to normal controls and correlates with disability. Furthermore, changes in CSA are detectable and correlate with changes in disability. Despite the technical difficulties of performing spinal cord MRI, imaging studies, particularly of the cervical cord, are becoming more common. Significant focus has been placed on measuring cord atrophy, and reproducible techniques have been developed to measure the cervical cord CSA. Spinal cord MRI may provide information about disease progression that is not readily available from brain MRI scans and could be useful in diagnosing MS in some cases, as well as for monitoring the effects of treatments.
Magnetic Resonance Imaging Advances in Multiple Sclerosis
Authors: Bakshi Rohit
Published: December 2005

Magnetic resonance imaging (MRI) has become a core component of clinical management and scientific research in multiple sclerosis (MS), providing essential information about tissue structure and function. MRI is now the most important laboratory diagnostic and longitudinal monitoring technology. A number of conventional MRI techniques, which include T2‐weighted, T1‐weighted, and gadolinium‐enhanced imaging, are used to identify overt lesions and quantify tissue atrophy. MRI is highly sensitive in detecting brain and spinal cord involvement in MS and can visualize multifocal lesions, occult disease, and macroscopic atrophy. Advanced MRI techniques, such as magnetization transfer imaging, spectroscopy, diffusionweighted imaging, and functional MRI, have added to our understanding of the pathogenesis of the disease. The precise role of these newer imaging approaches continues to be defined. In this supplement to the Journal of Neuroimaging, the authors review the role of conventional and advanced MRI techniques in detecting tissue changes in MS, diagnosing and monitoring patients, and charting the progression of disease in new and established patients.
Diffusion Tensor Magnetic Resonance Imaging in Multiple Sclerosis
Authors: Goldberg‐Zimring Daniel , Mewes Andrea U. J. , Maddah Mahnaz , Warfield Simon K.
Published: December 2005

Multiple sclerosis (MS), a demyelinating disease, occurs principally in the white matter (WM) of the central nervous system. Conventional magnetic resonance imaging (MRI) is sensitive to some, but not all, brain changes associated with MS. Diffusionweighted imaging (DWI) provides information about water diffusion in tissue and diffusion tensor MRI (DT‐MRI) about fiber direction, allowing for the identification of WMabnormalities that are not apparent on conventional MRI images. These techniques can quantitatively characterize the local microstructure of tissues. MS‐associated disease processes lead to regions characterized by an increased amount of water diffusion and a decrease in the anisotropy of diffusion direction. These changes have been found to produce different patterns in MS patients presenting different courses of the disease. Changes in water diffusion may allow examination of the type, appearance, enhancement, and location of lesions not readily visible by other means. Ongoing studies of MSare integrating conventional MRI and DT‐MRI measures with connectivity‐based regional assessment, aiming to provide a better understanding of the nature and the location of WM lesions. This integration and the development of novel image‐processing and visualization techniques may improve the understanding of WM architecture and its disruption in MS. This article presents a brief history of DWI, its basic principles and applications in the study of MS, a review of the properties and applications of DT‐MRI, and their use in the study of MS. In addition, this article illustrates the methodology for the analysis of DT‐MRI in ongoing studies of MS.
Measurement of Brain and Spinal Cord Atrophy by Magnetic Resonance Imaging as a Tool to Monitor Multiple Sclerosis
Authors: Bakshi Rohit , Dandamudi Venkata S. R. , Neema Mohit , De Chitradeep , Bermel Robert A.
Published: December 2005

Evaluation of brain and spinal cord atrophy by magnetic resonance imaging (MRI) has become an increasingly important component of understanding the multiple sclerosis (MS) disease process. These destructive aspects of the disease develop early in the disease course. A growing body of data links brain and spinal cord atrophy to clinical impairment more closely than can be linked with conventional measures of overt lesions. Thus, irreversible tissue damage may be a key factor leading to disease progression. In this review, the authors present the proposed mechanisms leading to central nervous system (CNS) atrophy. They describe the available MRI‐based techniques to measure regional and global atrophy of the brain and spinal cord. They compare the rate of atrophy among MS phenotypes and summarize the emerging data linking atrophy to neurological and neuropsychological impairment. Finally, they discuss the effect of disease‐modifying immunotherapies on the rate of CNS atrophy in patients with MS. Future research to clarify the etiology and pathophysiology of brain and spinal cord atrophy should provide new targets for therapeutic development.
Functional Magnetic Resonance Imaging and Multiple Sclerosis: The Evidence for Neuronal Plasticity
Authors: Buckle Guy J.
Published: December 2005

Blood oxygen level–dependent (BOLD) functional magnetic resonance imaging (fMRI) has emerged as a powerful technique to visualize the localization of cerebral activity in both healthy and diseased brains. BOLD fMRI has been used to assess brain function in a variety of diseases, including multiple sclerosis (MS), and has shown that altered patterns of connectivity are used to recruit more widespread eloquent brain networks engaged in tasks relating to motor activity, sensory and cognitive function, and memory when compared to normal controls. This review will examine the evidence that functional reorganization is a consequence of demyelination and tissue loss in MS that may serve as an adaptive response to limit clinical disability. It remains unclear whether cerebral plasticity is a marker of permanent functional restructuring or a short‐term compensatory response to injury. Long‐term longitudinal studies that correlate fMRI activity with other MRI markers of disease burden and activity, as well as with clinical measures of disease activity and progression, are badly needed to determine fMRI's relevance to clinical practice and its place as a surrogate outcome measure in MS.
Magnetic Resonance Spectroscopy in the Monitoring of Multiple Sclerosis
Authors: Narayana Ponnada A.
Published: December 2005

In addition to providing information on tissue structure, magnetic resonance (MR) technology offers the potential to investigate tissue metabolism and function. MR spectroscopy (MRS) offers a wealth of data on the biochemistry of a selected brain tissue volume, which represent potential surrogate markers for the pathology underlying multiple sclerosis (MS). In particular, the N‐acetylaspartate peak in an MR spectrum is a putative marker of neuronal and axonal integrity, and the choline peak appears to reflect cell‐membrane metabolism. On this basis, a diminished N‐acetylaspartate peak is interpreted to represent neuronal/axonal dysfunction or loss, and an elevated choline peak represents heightened cell‐membrane turnover, as seen in demyelination, remyelination, inflammation, or gliosis. Therefore, MRS may provide a unique tool to evaluate the severity of MS, establish a prognosis, follow disease evolution, understand its pathogenesis, and evaluate the efficacy of therapeutic interventions, which complements the information obtained from the various forms of assessment made by conventional MR imaging.
Greater risk of incident asthma cases in adults with Allergic Rhinitis and Effect of Allergen Immunotherapy: A Retrospective Cohort Study
Authors: Polosa Riccardo , Al-Delaimy Wael K , Russo Cristina , Piccillo Giovita , Sarvà Maria
Published: December 2005

Asthma and rhinitis are often co-morbid conditions. As rhinitis often precedes asthma it is possible that effective treatment of allergic rhinitis may reduce asthma progression.

The aim of our study is to investigate history of allergic rhinitis as a risk factor for asthma and the potential effect of allergen immunotherapy in attenuating the incidence of asthma.

Hospital-referred non-asthmatic adults, aged 18–40 years between 1990 and 1991, were retrospectively followed up until January and April 2000. At the end of follow up, available subjects were clinically examined for asthma diagnosis and history of allergen specific immunotherapy, second-hand smoking and the presence of pets in the household. A total of 436 non-asthmatic adults (332 subjects with allergic rhinitis and 104 with no allergic rhinitis nor history of atopy) were available for final analyses.

The highest OR (odds ratio) associated with a diagnosis of asthma at the end of follow-up was for the diagnosis of allergic rhinitis at baseline (OR, 7.8; 95%CI, 3.1–20.0 in the model containing the covariates of rhinitis diagnosis, sex, second-hand smoke exposure, presence of pets at home, family history of allergic disorders, sensitization toParietaria judaica; grass pollen; house dust mites;Olea europea: orchard; perennial rye; and cat allergens). Female sex, sensitization toParietaria judaicaand the presence of pets in the home were also significantly predictive of new onset asthma in the same model. Treatment with allergen immunotherapy was significantly and inversely related to the development of new onset asthma (OR, 0.53; 95%CI, 0.32–0.86).

In the present study we found that allergic rhinitis is an important independent risk factor for asthma. Moreover, treatment with allergen immunotherapy lowers the risk of the development of new asthma cases in adults with allergic rhinitis.
Comparison of normalization methods for CodeLink Bioarray data
Authors: Wu Wei , Dave Nilesh , Tseng George C , Richards Thomas , Xing Eric P , Kaminski Naftali
Published: December 2005

Background

The quality of microarray data can seriously affect the accuracy of downstream analyses. In order to reduce variability and enhance signal reproducibility in these data, many normalization methods have been proposed and evaluated, most of which are for data obtained from cDNA microarrays and Affymetrix GeneChips. CodeLink Bioarrays are a newly emerged, single-color oligonucleotide microarray platform. To date, there are no reported studies that evaluate normalization methods for CodeLink Bioarrays.

Results

We compared five existing normalization approaches, in terms of both noise reduction and signal retention: Median (suggested by the manufacturer), CyclicLoess, Quantile, Iset, and Qspline. These methods were applied to two real datasets (a time course dataset and a lung disease-related dataset) generated by CodeLink Bioarrays and were assessed using multiple statistical significance tests. Compared to Median, CyclicLoess and Qspline exhibit a significant and the most consistent improvement in reduction of variability and retention of signal. CyclicLoess appears to retain more signal than Qspline. Quantile reduces more variability than Median in both datasets, yet fails to consistently retain more signal in the time course dataset. Iset does not improve over Median in either noise reduction or signal enhancement in the time course dataset.

Conclusion

Median is insufficient either to reduce variability or to retain signal effectively for CodeLink Bioarray data. CyclicLoess is a more suitable approach for normalizing these data. CyclicLoess also seems to be the most effective method among the five different normalization strategies examined.
Classification of real and pseudo microRNA precursors using local structure-sequence features and support vector machine
Authors: Xue Chenghai , Li Fei , He Tao , Liu Guo-Ping , Li Yanda , Zhang Xuegong
Published: December 2005

Background

MicroRNAs (miRNAs) are a group of short (~22 nt) non-coding RNAs that play important regulatory roles. MiRNA precursors (pre-miRNAs) are characterized by their hairpin structures. However, a large amount of similar hairpins can be folded in many genomes. Almost all current methods for computational prediction of miRNAs use comparative genomic approaches to identify putative pre-miRNAs from candidate hairpins. Ab initio method for distinguishing pre-miRNAs from sequence segments with pre-miRNA-like hairpin structures is lacking. Being able to classify real vs. pseudo pre-miRNAs is important both for understanding of the nature of miRNAs and for developing ab initio prediction methods that can discovery new miRNAs without known homology.

Results

A set of novel features of local contiguous structure-sequence information is proposed for distinguishing the hairpins of real pre-miRNAs and pseudo pre-miRNAs. Support vector machine (SVM) is applied on these features to classify real vs. pseudo pre-miRNAs, achieving about 90% accuracy on human data. Remarkably, the SVM classifier built on human data can correctly identify up to 90% of the pre-miRNAs from other species, including plants and virus, without utilizing any comparative genomics information.

Conclusion

The local structure-sequence features reflect discriminative and conserved characteristics of miRNAs, and the successful ab initio classification of real and pseudo pre-miRNAs opens a new approach for discovering new miRNAs.
Construction and validation of the APOCHIP, a spotted oligo-microarray for the study of beta-cell apoptosis
Authors: Magnusson Nils E , Cardozo Alessandra K , Kruhøffer Mogens , Eizirik Decio L , Ørntoft Torben F , Jensen Jens L
Published: December 2005

Background

Type 1 diabetes mellitus (T1DM) is a autoimmune disease caused by a long-term negative balance between immune-mediated beta-cell damage and beta-cell repair/regeneration. Following immune-mediated damage the beta-cell fate depends on several genes up- or down-regulated in parallel and/or sequentially. Based on the information obtained by the analysis of several microarray experiments of beta-cells exposed to pro-apoptotic conditions (e.g. double stranded RNA (dsRNA) and cytokines), we have developed a spotted rat oligonucleotide microarray, the APOCHIP, containing 60-mer probes for 574 genes selected for the study of beta-cell apoptosis.

Results

The APOCHIP was validated by a combination of approaches. First we performed an internal validation of the spotted probes based on a weighted linear regression model using dilution series experiments. Second we profiled expression measurements in ten dissimilar rat RNA samples for 515 genes that were represented on both the spotted oligonucleotide collection and on the in situ-synthesized 25-mer arrays (Affymetrix GeneChips). Internal validation showed that most of the spotted probes displayed a pattern of reaction close to that predicted by the model. By using simple rules for comparison of data between platforms we found strong correlations (rmedian= 0.84) between relative gene expression measurements made with spotted probes and in situ-synthesized 25-mer probe sets.

Conclusion

In conclusion our data suggest that there is a high reproducibility of the APOCHIP in terms of technical replication and that relative gene expression measurements obtained with the APOCHIP compare well to the Affymetrix GeneChip. The APOCHIP is available to the scientific community and is a useful tool to study the molecular mechanisms regulating beta-cell apoptosis.
Functional studies of signaling pathways in peri-implantation development of the mouse embryo by RNAi
Authors: Soares Miguel L , Haraguchi Seiki , Torres-Padilla Maria-Elena , Kalmar Tibor , Carpenter Lee , Bell Graham , Morrison Alastair , Ring Christopher JA , Clarke Neil J , Glover David M , Zernicka-Goetz Magdalena
Published: December 2005

Background

Studies of gene function in the mouse have relied mainly on gene targeting via homologous recombination. However, this approach is difficult to apply in specific windows of time, and to simultaneously knock-down multiple genes. Here we report an efficient method for dsRNA-mediated gene silencing in late cleavage-stage mouse embryos that permits examination of phenotypes at post-implantation stages.

Results

We show that introduction of Bmp4 dsRNA into intact blastocysts by electroporation recapitulates the genetic Bmp4 null phenotype at gastrulation. It also reveals a novel role for Bmp4 in the regulation the anterior visceral endoderm specific gene expression and its positioning. We also show that RNAi can be used to simultaneously target several genes. When applied to the three murine isoforms of Dishevelled, it leads to earlier defects than previously observed in double knock-outs. These include severe delays in post-implantation development and defects in the anterior midline and neural folds at headfold stages.

Conclusion

Our results indicate that the BMP4 signalling pathway contributes to the development of the anterior visceral endoderm, and reveal an early functional redundancy between the products of the murine Dishevelled genes. The proposed approach constitutes a powerful tool to screen the functions of genes that govern the development of the mouse embryo.
The Academic Medical Center Linear Disability Score (ALDS) item bank: item response theory analysis in a mixed patient population
Authors: Holman Rebecca , Weisscher Nadine , Glas Cees AW , Dijkgraaf Marcel GW , Vermeulen Marinus , de Haan Rob J , Lindeboom Robert
Published: December 2005

Background

Currently, there is a lot of interest in the flexible framework offered by item banks for measuring patient relevant outcomes. However, there are few item banks, which have been developed to quantify functional status, as expressed by the ability to perform activities of daily life. This paper examines the measurement properties of the Academic Medical Center linear disability score item bank in a mixed population.

Methods

This paper uses item response theory to analyse data on 115 of 170 items from a total of 1002 respondents. These were: 551 (55%) residents of supported housing, residential care or nursing homes; 235 (23%) patients with chronic pain; 127 (13%) inpatients on a neurology ward following a stroke; and 89 (9%) patients suffering from Parkinson's disease.

Results

Of the 170 items, 115 were judged to be clinically relevant. Of these 115 items, 77 were retained in the item bank following the item response theory analysis. Of the 38 items that were excluded from the item bank, 24 had either been presented to fewer than 200 respondents or had fewer than 10% or more than 90% of responses in the category 'can carry out'. A further 11 items had different measurement properties for younger and older or for male and female respondents. Finally, 3 items were excluded because the item response theory model did not fit the data.

Conclusion

The Academic Medical Center linear disability score item bank has promising measurement characteristics for the mixed patient population described in this paper. Further studies will be needed to examine the measurement properties of the item bank in other populations.
Changes in microRNA expression profiles in HIV-1-transfected human cells
Authors: Yeung Man Lung , Bennasser Yamina , Myers Timothy G , Jiang Guojian , Benkirane Monsef , Jeang Kuan-Teh
Published: December 2005

MicroRNAs (miRNAs) are small RNAs of 18–25 nucleotides (nt) in length that play important roles in regulating a variety of biological processes. Recent studies suggest that cellular miRNAs may serve to control the replication of viruses in cells. If such is the case, viruses might be expected to evolve the ability to modulate the expression of cellular miRNAs. To ask if expression of HIV-1 genes changes the miRNA profiles in human cells, we employed a high throughput microarray method, termed the RNA-primed Array-based Klenow Enzyme (RAKE) assay. Here, we describe the optimization of this assay to quantify the expression of miRNAs in HIV-1 transfected human cells. We report distinct differences in miRNA profiles in mock-transfected HeLa cells versus HeLa cells transfected with an infectious HIV-1 molecular clone, pNL4-3.
IX international conference on Salt Lake research: Research opportunities and management challenges
Authors: Jellison Robert
Published: December 2005

The 9th International Conference on Salt Lake Research was held 26–30 September 2005 in Western Australia at the Curtin University of Technology, Perth, Australia. One hundred scientists from 10 countries presented research on a diverse array of topics highlighting research findings and opportunities, and management challenges associated with inland saline waters. Major emergent themes of the conference included modeling of ecosystem processes, microbial communities, and features of Western Australian inland saline environments, including current threats, conservation and management.
Intelligent Management of Helicopter Health and Usage Management Systems Data
Authors: Knight P , Cook J , Azzam H
Published: December 2005

Helicopter health and usage management systems (HUMS) generate large amounts of data, which are downloaded to ground-based systems. The data are automatically examined on download for damage indications, which provide the immediate go/no-go response required by the aircraft operations management. This level of reactive fault detection and diagnosis is reasonably well understood and has been demonstrated to improve aircraft availability and airworthiness. To achieve further benefit and maintenance cost savings from HUMS, another level of analysis is required, leading to prognostics and predictive maintenance through intelligent management (IM) of the accumulated HUMS records. In collaboration with the Civil Aviation Authority (CAA), Smiths has developed a suite of IM methods and has successfully applied them to gearbox seeded fault data. Working closely with the UK Ministry of Defence (UK MOD), Smiths has tested these methods on Chinook HUMS data, including an in-flight transmission bearing failure incident described in this article. The result is a high degree of early anomaly detection and a clear view of the deterioration to failure. The objective of the MOD programme has been to apply IM tools to the enormous quantity of HUMS data being gathered, thereby enabling improved analysis capability, increased levels of automation, and more intelligent use of resources. The article presents the results of the work carried out under both the CAA and the MOD programmes.
Double Acting Tanker: Experiences from Model Tests and Sea Trials
Authors: Trägärdh P , Lindell P , Sasaki N
Published: December 2005

The acronym DAT stands for double acting tanker, a concept where the ship is designed to run astern in heavy ice conditions while remaining hydrodynamically efficient for ahead propulsion in open water conditions. Two large aframax DATs - 106.000 dwt (deadweight tons) each - have been delivered by Sumitomo Heavy Industries to Fortum Oil and Gas OY. They are the first crude carriers built according to the DAT principle and also the first using pod propulsion from the beginning (Fig. 1). They will also be the world's largest crude carriers with ice class 1A super and are primarily intended for year-round transportation of North Sea crude to Fortum's refineries in the Gulf of Finland. The ships were appointed ‘ship of the year’ in Japan in 2003.

SSPA was contracted by Sumitomo Heavy Industries to perform model tests. A comprehensive open water model test programme was used to investigate aspects of resistance and propulsion, manoeuvring, and cavitation performance. As the ship is designed to operate both in ahead and astern conditions for prolonged periods of time, most tests were performed both ahead and astern. Also, a simulation study of dynamic positioning at buoy or floating production, storage offshore (FPSO) loading was made by SSPA. Comprehensive tests of the ship's performance in ice were performed in the ice tank at MARC (Masa-Yards Artic Research Centre).

The eight-month model testing and development campaign resulted in a ship with excellent propulsion and manoeuvring performance, especially with regard to the high ice class. Sea trials carried out with ship in August 2002 confirmed the results of the model test. Interesting experiences of the model test campaign and comparison between model test and sea trial results are presented, as well as some examples of single-point mooring simulations.
Multisensor Data Fusion Applied to Marine Integrated Navigation Systems
Authors: Tiano A , Zirilli A , Cuneo M , Pagnan S
Published: December 2005

This paper deals with the problem of designing a flexible and accurate integrated navigation system (INS) for marine craft. The proposed INS is based on the integration of a global positioning system (GPS) with a compass and a speed log. After introducing the scopes and functions of the proposed INS, mathematical models of its main components are presented. Then the development of a new multisensor data fusion algorithm for carrying out an accurate estimation of the main state variables is presented. The theoretical background for the sensor fusion is based on the classical Kalman filter theory, which allows to update an a priori position estimate, given by a dead-reckoning system, with the information supplied by a GPS positioning system. Finally the filtering algorithm is extended in the framework of interval analysis and fuzzy set theory in order to improve the reliability and robustness of the estimation algorithm. The validity of the proposed approach is demonstrated by simulation examples applied to a container ship navigating in realistic conditions.
Development of a New Interfacing Strategy for Fluid-Structure Interaction
Authors: Huang L L , Riggs H R
Published: December 2005

Displacement and pressure transfer between fluid and structure meshes in fluidstructure interaction analysis is complicated substantially when the two meshes on the domain interface are different and therefore form two distinct surfaces in three-dimensional space. A new, approximately energy-conserving interfacing strategy with two distinct components - mapping and interpolation - is proposed. The mapping between meshes is based on the assumption of a common parametric-based description of the wetted surface. The interpolation strategy is based on the smoothing element analysis method developed to recover stresses in finite element analysis, with an additional term to impose an energy-conserving constraint. The method is evaluated numerically with several examples from linear hydrodynamics/hydroelasticity. The advantage of these examples is that the components can be evaluated separately, and the performance of the method can be examined more clearly. Numerical results show the method is quite promising.
Immobilization of Residual Basic Dyes onto Polyamide Ion-Exchanger Materials
Authors: Baouab Mohamed Hassen V , Khalfaoui Mohamed , Bartegi Aghleb , Gauthier Robert
Published: December 2005

This paper reports the preparation of methacrylic acid-grafted nylon (MAA—nylon) by treating nylon-6,6 fibres with methacrylic acid (MAA) and the use of this modified polyamide as an ion-exchanger for the immobilization of pollutant basic dyes. The grafting of MAA onto nylon-6,6 was demonstrated both by weight uptake and atomic force microscopy. The exchange capacity of MAA—nylon was evaluated by potentiometric titration of the acidic groups. Five MAA—nylon fibres with different degrees of grafting (20–80%) were tested for the adsorption of two basic dyes, viz. Basic Blue 3 and Basic Red 24. Such adsorption was monitored by visible spectroscopy. The adsorption capacity was found to depend on the degree of grafting and on the temperature. The experimental data were fitted using the Langmuir and Freundlich models. However, an improved fit could be obtained by using the Jossens model.
Adsorption and Gas Chromatographic Properties of Fluorinated Carbon
Authors: Roshchina Tatiana M. , Shonia Natalia K. , Glazkova Svetlana V.
Published: December 2005

Carbon fibre (C) and adsorbent prepared from fluorinated carbon fibre (FC) have been studied by adsorption and gas chromatography (GC). An extreme growth in the specific surface area of C was observed as a result of fluorination, although the homogeneity of FC was increased in comparison to that of C. Heats and standard adsorption entropies for a number of compounds have been measured by GC. It was shown that the FC sample was characterized by a highly hydrophobic and chemically homogeneous surface of low polarity.
Surface Properties of Synthetic Calcium Hydroxyapatite
Authors: Nikolenko N.V. , Esajenko E.E.
Published: December 2005

The composition of the adsorption centres of hydrated calcium hydroxyapatite was studied. It was found that the adsorption of organic bases was due to the formation of surface hydrogen bonds between their nitrogen atoms and the ≡POH groups of hydroxyapatite. Aromatic acids and alcohols were adsorbed in an ionic form due to the formation of intraspheric complexes with surface Ca2+ cations. It was concluded that the adsorbability of organic compounds depends on the relationship between the greatest effective charges on their atoms and the atoms of water molecules.
Removal of Some Heavy Metal Cations from Aqueous Solution by Adsorption onto Natural Kaolin
Authors: Ceylan H. , Şahan T. , Gürkan R. , Kubilay Ş.
Published: December 2005

The adsorption removal of some heavy metal cations such as Cu(II), Zn(II) and Co(II) from aqueous solution onto kaolin has been studied using the batch method with initial metal ion concentrations within the range 15–70 mg/l. The percentage adsorption and equilibrium concentrations were determined by means of atomic absorption flame photometry as a function of adsorbate concentration, pH and temperature.

Ion-exchange studies showed that over the complete concentration range studied the adsorption ratios for metal cations adsorbed onto kaolin correlated with the linear forms of the Langmuir, Freundlich and Dubinin—Kaganer—Radushkevich (DKR) adsorption isotherms. The cationexchange capacity of kaolin towards each metal ion studied was evaluated. It was found that the adsorption phenomena depended on the charge density and diameter of the hydrated ion. The equilibrium studies demonstrated that the selectivity of the ions followed the sequence Zn(II) > Cu(II) > Co(II) at pH 7.0. Calculation of thermodynamic parameters such as the standard enthalpy (ΔH0), Gibbs free energy (ΔG0) and entropy (ΔS0) showed that the adsorption of the heavy metal ions studied onto kaolin was an endothermic process which was favoured at higher temperatures.

These results show that natural kaolin has a considerable potential for the removal of heavy metal cationic species from aqueous solution and wastewater.
Storage of Methane in Resin Carbon Beads and Discs
Authors: Alain Emmanuelle , McEnaney Brian
Published: December 2005

Porous resin beads can be produced by the emulsion polycondensation of lignosulphonates with crosslinking agents. These resins can be converted into active carbon beads or pressed into discs that can be converted into active carbon monoliths. The stored methane volumetric capacity of the active carbon discs exceeded 150 v/v while the delivered capacity approached this value. The delivered capacity could be increased if steps were taken to release the large amount of methane retained in micropores after decompression. The volumetric methane capacities of the carbon beads were lower than those for the discs due to the presence of interparticulate voids.
On Aerodynamic Stability of Membrane Structures
Authors: Yang Qing-Shan , Liu Rui-Xia
Published: December 2005

The aerodynamic instability critical wind velocity of three-dimensional membrane structures is studied by combining the non-moment theory of thin shallow shells and the potential flow theory in fluids. The dynamic equilibrium equation of the structure is established by applying the non-moment theory of thin shells, with the assumption that the coming flow is uniform ideal potential flow. The aerodynamic interaction equations of the membrane structure in two cases, i.e., the wind is in the structural arch or sag direction, are obtained based on the aerodynamic forces being determined by applying the potential flow theory and the thin airfoils theory in which the wind-structure interaction is taken into account. Bubnov-Galerkin approximate method is applied to transform the interaction equation into a second order linear ordinary differential equation; and the instability critical wind velocity is obtained from Routh-Hurwitz stability criterion.
Effect of Ring Beam Stiffness on Behaviour of Reticulated Timber Domes
Authors: Pan Dan H. , Girhammar Ulf Arne
Published: December 2005

Domes are efficient structural systems for long clear-span buildings. The introduction of laminated timber highlighted the economic advantages of this material and led to the use of timber domes even for very large spans. In this paper, reticulated timber domes of triangular network shape with decking and bottom tension ring are considered. These types of domes have high stiffness in all directions along the surface and are kinematically stable. The dome is subjected to uniformly distributed load over the entire structure. The dome model is generated with a preprocessor program called DOME-IN and analysed with ABAQUS.

The focus of this paper is to evaluate the behaviour of reticulated timber domes with respect to different stiffnesses of the bottom ring beam, here defined as a non-dimensional ring beam area parameter Ar*, which is shown to be a very well adapted design parameter for the ring beam.

As far as global buckling is concerned, the critical pressure is sensitive to the bottom ring beam stiffness only if the latter is within a certain range. In terms of design, the stiffness of the ring beam should exceed A* > 2 in order to utilise the full buckling load capacity of the dome system itself. The maximum deflection, normal forces and bending moments versus the ring beam area parameter are also evaluated. The maximum values of the deflection and the internal actions next to the bottom ring are very sensitive to the bottom ring beam stiffness only if the latter is less than about Ar* < 10. A recommended value for the design of the bottom ring beam is A* > 20.