bluuebunny/crossref_metadata_2025 huggingface dataset:
Nuclear Receptor Signaling and Cardiac Energetics
Authors: Huss Janice M. , Kelly Daniel P.
Published: September 2004

The heart has a tremendous capacity for ATP generation, allowing it to function as an efficient pump throughout the life of the organism. The adult myocardium uses either fatty acid or glucose oxidation as its main energy source. Under normal conditions, the adult heart derives most of its energy through oxidation of fatty acids in mitochondria. However, the myocardium has a remarkable ability to switch between carbohydrate and fat fuel sources so that ATP production is maintained at a constant rate in diverse physiological and dietary conditions. This fuel selection flexibility is important for normal cardiac function. Although cardiac energy conversion capacity and metabolic flux is modulated at many levels, an important mechanism of regulation occurs at the level of gene expression. The expression of genes involved in multiple energy transduction pathways is dynamically regulated in response to developmental, physiological, and pathophysiological cues. This review is focused on gene transcription pathways involved in short- and long-term regulation of myocardial energy metabolism. Much of our knowledge about cardiac metabolic regulation comes from studies focused on mitochondrial fatty acid oxidation. The genes involved in this key energy metabolic pathway are transcriptionally regulated by members of the nuclear receptor superfamily, specifically the fatty acid-activated peroxisome proliferator-activated receptors (PPARs) and the nuclear receptor coactivator, PPARγ coactivator-1α (PGC-1α). The dynamic regulation of the cardiac PPAR/PGC-1 complex in accordance with physiological and pathophysiological states will be described.
Inhibition of Akt increases p27Kip1 levels and induces cell cycle arrest in anaplastic large cell lymphoma
Authors: Rassidakis George Z. , Feretzaki Marianna , Atwell Coralyn , Grammatikakis Ioannis , Lin Quan , Lai Raymond , Claret Francois-Xavier , Medeiros L. Jeffrey , Amin Hesham M.
Published: September 2004

Anaplastic large cell lymphoma (ALCL) is a highly proliferative neoplasm that frequently carries the t(2;5)(p23;q35) and aberrantly expresses nucleophosmin–anaplastic lymphoma kinase (NPM-ALK). Previously, NPM-ALK had been shown to activate the phosphatidylinositol 3 kinase (PI3K)/Akt pathway. As the cyclin-dependent kinase (CDK) inhibitor p27Kip1 (p27) is usually not expressed in ALCL, we hypothesized that activated Akt (pAkt) phosphorylates p27 resulting in increased p27 proteolysis and cell cycle progression. Here we demonstrate that inhibition of pAkt activity in ALCL decreases p27 phosphorylation and degradation, resulting in increased p27 levels and cell cycle arrest. Using immunohistochemistry, pAkt was detected in 24 (57%) of 42 ALCL tumors, including 8 (44%) of 18 ALK-positive tumors and 16 (67%) of 24 ALK-negative tumors, and was inversely correlated with p27 levels. The mean percentage of p27-positive tumor cells was 5% in the pAkt-positive group compared with 26% in the pAkt-negative group (P = .0076). These findings implicate that Akt activation promotes cell cycle progression through inactivation of p27 in ALCL.
An integrated 4249 marker FISH/RH map of the canine genome
Authors: Breen Matthew , Hitte Christophe , Lorentzen Travis D , Thomas Rachael , Cadieu Edouard , Sabacan Leah , Scott Allyson , Evanno Gwenaelle , Parker Heidi G , Kirkness Ewen F , Hudson Ruth , Guyon Richard , Mahairas Gregory G , Gelfenbeyn Boris , Fraser Claire M , André Catherine , Galibert Francis , Ostrander Elaine A
Published: September 2004

Background

The 156 breeds of dog recognized by the American Kennel Club offer a unique opportunity to map genes important in genetic variation. Each breed features a defining constellation of morphological and behavioral traits, often generated by deliberate crossing of closely related individuals, leading to a high rate of genetic disease in many breeds. Understanding the genetic basis of both phenotypic variation and disease susceptibility in the dog provides new ways in which to dissect the genetics of human health and biology.

Results

To facilitate both genetic mapping and cloning efforts, we have constructed an integrated canine genome map that is both dense and accurate. The resulting resource encompasses 4249 markers, and was constructed using the RHDF5000-2 whole genome radiation hybrid panel. The radiation hybrid (RH) map features a density of one marker every 900 Kb and contains 1760 bacterial artificial chromosome clones (BACs) localized to 1423 unique positions, 851 of which have also been mapped by fluorescence in situ hybridization (FISH). The two data sets show excellent concordance. Excluding the Y chromosome, the map features an RH/FISH mapped BAC every 3.5 Mb and an RH mapped BAC-end, on average, every 2 Mb. For 2233 markers, the orthologous human genes have been established, allowing the identification of 79 conserved segments (CS) between the dog and human genomes, dramatically extending the length of most previously described CS.

Conclusions

These results provide a necessary resource for the canine genome mapping community to undertake positional cloning experiments and provide new insights into the comparative canine-human genome maps.
Transformation and scattering activities of the receptor tyrosine kinase RON/Stk in rodent fibroblasts and lack of regulation by the jaagsiekte sheep retrovirus receptor, Hyal2
Authors: Miller A Dusty , Van Hoeven Neal S , Liu Shan-Lu
Published: September 2004

Background

The envelope (Env) protein of jaagsiekte sheep retrovirus (JSRV) can transform cells in culture and is likely to be the main factor responsible for lung cancer induction by JSRV in animals. A recent report indicates that the epithelial-cell transforming activity of JSRV Env depends on activation of the cell-surface receptor tyrosine kinase Mst1r (called RON for the human and Stk for the rodent orthologs). In the immortalized line of human epithelial cells used (BEAS-2B cells), the virus receptor Hyal2 was found to bind to and suppress the activity of RON. When Env was expressed it bound to Hyal2 causing its degradation, release of RON activity from Hyal2 suppression, and activation of pathways resulting in cell transformation.

Methods

Due to difficulty with reproducibility of the transformation assay in BEAS-2B cells, we have used more tractable rodent fibroblast models to further study Hyal2 modulation of RON/Stk transforming activity and potential effects of Hyal2 on RON/Stk activation by its natural ligand, macrophage stimulating protein (MSP).

Results

We did not detect transformation of NIH 3T3 cells by plasmids expressing RON or Stk, but did detect transformation of 208F rat fibroblasts by these plasmids at a very low rate. We were able to isolate 208F cell clones that expressed RON or Stk and that showed changes in morphology indicative of transformation. The parental 208F cells did not respond to MSP but 208F cells expressing RON or Stk showed obvious increases in scattering/transformation in response to MSP. Human Hyal2 had no effect on the basal or MSP-induced phenotypes of RON-expressing 208F cells, and human, mouse or rat Hyal2 had no effect on the basal or MSP-induced phenotypes of Stk-expressing 208F cells.

Conclusions

We have shown that RON or Stk expression in 208F rat fibroblasts results in a transformed phenotype that is enhanced by addition of the natural ligand for these proteins, MSP. Hyal2 does not directly modulate the basal or MSP-induced RON/Stk activity, although it is possible that adaptor proteins might mediate such signaling in other cell types.
High-dose ibuprofen therapy associated with esophageal ulceration after pneumonectomy in a patient with cystic fibrosis: a case report
Authors: Mackey Jennifer E , Anbar Ran D
Published: September 2004

Background

Lung disease in patients with cystic fibrosis is thought to develop as a result of airway inflammation, infection, and obstruction. Pulmonary therapies for cystic fibrosis that reduce airway inflammation include corticosteroids, rhDNase, antibiotics, and high-dose ibuprofen. Despite evidence that high-dose ibuprofen slows the progression of lung disease in patients with cystic fibrosis, many clinicians have chosen not to use this therapy because of concerns regarding potential side effects, especially gastrointestinal bleeding. However, studies have shown a low incidence of gastrointestinal ulceration and bleeding in patients with cystic fibrosis who have been treated with high-dose ibuprofen.

Case presentation

The described case illustrates a life-threatening upper gastrointestinal bleed that may have resulted from high-dose ibuprofen therapy in a patient with CF who had undergone a pneumonectomy. Mediastinal shift post-pneumonectomy distorted the patient's esophageal anatomy and may have caused decreased esophageal motility, which led to prolonged contact of the ibuprofen with the esophagus. The concentrated effect of the ibuprofen, as well as its systemic effects, probably contributed to the occurrence of the bleed in this patient.

Conclusions

This report demonstrates that gastrointestinal tract anatomical abnormalities or dysmotility may be contraindications for therapy with high-dose ibuprofen in patients with cystic fibrosis.
Validity and reproducibility of an interviewer-administered food frequency questionnaire for healthy French-Canadian men and women
Authors: Goulet Julie , Nadeau Geneviève , Lapointe Annie , Lamarche Benoît , Lemieux Simone
Published: September 2004

Objective

To evaluate the validity (study 1) and the reproducibility (study 2) of an interviewer-administered food frequency questionnaire (FFQ).

Method

The FFQ was designed at Laval University and contains 91 items and 33 subquestions. Study 1: The FFQ was compared against a 3-day food record (2 week-days and 1 weekend-day), at week 0, 6 and 12 of a nutritional intervention. Study 2: In order to evaluate the reproducibility of the FFQ, 2 registered dietitians administered the FFQ 4-weeks apart among subjects who were not part of the nutritional intervention.

Results

Study 1: Mean values for intake of most nutrients assessed by the FFQ and by the 3-day food record were not statistically different. Energy-adjusted correlation coefficients for major macronutrients ranged from 0.36 for proteins to 0.60 for carbohydrates (p ≤ 0.01). Agreement analysis revealed that on average, 35% of the subjects were classified in the same quartile when nutrients were assessed by either the 3-day food record or the FFQ. Study 2: Significant associations were observed between dietary measurements derived from the two FFQs administered 4 weeks apart. Correlation coefficients for the reproducibility of macronutrients ranged from 0.66 for carbohydrates to 0.83 for lipids after energy adjustment. On average, 46% of the subjects were classified in the same quartile when nutrient intakes were assessed by either FFQ.

Conclusion

These data indicated that the FFQ developed has a good validity and is reproducible.
Anogenital distance in human male and female newborns: a descriptive, cross-sectional study
Authors: Salazar-Martinez Eduardo , Romano-Riquer Patricia , Yanez-Marquez Edith , Longnecker Matthew P , Hernandez-Avila Mauricio
Published: September 2004

Background

In animal studies of the effects of hormonally active agents, measurement of anogenital distance (AGD) is now routine, and serves as a bioassay of fetal androgen action. Although measurement of AGD in humans has been discussed in the literature, to our knowledge it has been measured formally in only two descriptive studies of females. Because AGD has been an easy-to-measure, sensitive outcome in animals studies, we developed and implemented an anthropometric protocol for measurement of AGD in human males as well as females.

Methods

We first evaluated the reliability of the AGD measures in 20 subjects. Then measurements were taken on an additional 87 newborns (42 females, 45 males). All subjects were from Morelos, Mexico.

Results

The reliability (Pearson r) of the AGD measure was, for females 0.50, and for males, 0.64. The between-subject variation in AGD, however, was much greater than the variation due to measurement error. The AGD measure was about two-fold greater in males (mean, 22 mm) than in females (mean, 11 mm), and there was little overlap in the distributions for males and females.

Conclusion

The sexual dimorphism of AGD in humans comprises prima facie evidence that this outcome may respond to in utero exposure to hormonally active agents.
Prevention of non-communicable diseases in Pakistan: an integrated partnership-based model
Authors: Nishtar Sania
Published: September 2004

Development and implementation of non-communicable disease (NCD) prevention polices in the developing countries is a multidimensional challenge. This article highlights the evolution of a strategic approach in Pakistan. The model is evidence-based and encompasses a concerted and integrated approach to NCDs. It has been modelled to impact a set of indicators through the combination of a range of actions capitalizing on the strengths of a public-private partnership. The paper highlights the merits and limitations of this approach. The experience outlines a number of clear imperatives for fostering an enabling environment for integrated NCD prevention public health models, which involve roles played by a range of stakeholders. It also highlights the value that such partnership arrangements bring in facilitating the mission and mandates of ministries of health, international agencies with global health mandates, and the non-profit private sector. The experience is of relevance to developing countries that have NCD programs running and those that need to develop them. It provides an empirical basis for enhancing the performance of the health system by fostering partnerships within integrated evidence-based models and permits an analysis of health systems models built on shared responsibility for the purpose of providing sustainable health outcomes.
A scale of functional divergence for yeast duplicated genes revealed from analysis of the protein-protein interaction network
Authors: Baudot Anaïs , Jacq Bernard , Brun Christine
Published: September 2004

Background

Studying the evolution of the function of duplicated genes usually implies an estimation of the extent of functional conservation/divergence between duplicates from comparison of actual sequences. This only reveals the possible molecular function of genes without taking into account their cellular function(s). We took into consideration this latter dimension of gene function to approach the functional evolution of duplicated genes by analyzing the protein-protein interaction network in which their products are involved. For this, we derived a functional classification of the proteins using PRODISTIN, a bioinformatics method allowing comparison of protein function. Our work focused on the duplicated yeast genes, remnants of an ancient whole-genome duplication.

Results

Starting from 4,143 interactions, we analyzed 41 duplicated protein pairs with the PRODISTIN method. We showed that duplicated pairs behaved differently in the classification with respect to their interactors. The different observed behaviors allowed us to propose a functional scale of conservation/divergence for the duplicated genes, based on interaction data. By comparing our results to the functional information carried by GO annotations and sequence comparisons, we showed that the interaction network analysis reveals functional subtleties, which are not discernible by other means. Finally, we interpreted our results in terms of evolutionary scenarios.

Conclusions

Our analysis might provide a new way to analyse the functional evolution of duplicated genes and constitutes the first attempt of protein function evolutionary comparisons based on protein-protein interactions.
Bioconductor: open software development for computational biology and bioinformatics
Authors: Gentleman Robert C , Carey Vincent J , Bates Douglas M , Bolstad Ben , Dettling Marcel , Dudoit Sandrine , Ellis Byron , Gautier Laurent , Ge Yongchao , Gentry Jeff , Hornik Kurt , Hothorn Torsten , Huber Wolfgang , Iacus Stefano , Irizarry Rafael , Leisch Friedrich , Li Cheng , Maechler Martin , Rossini Anthony J , Sawitzki Gunther , Smith Colin , Smyth Gordon , Tierney Luke , Yang Jean YH , Zhang Jianhua
Published: September 2004

The Bioconductor project is an initiative for the collaborative creation of extensible software for computational biology and bioinformatics. The goals of the project include: fostering collaborative development and widespread use of innovative software, reducing barriers to entry into interdisciplinary scientific research, and promoting the achievement of remote reproducibility of research results. We describe details of our aims and methods, identify current challenges, compare Bioconductor to other open bioinformatics projects, and provide working examples.
The JAK3 inhibitor CP-690550 selectively reduces NK and CD8+ cell numbers in cynomolgus monkey blood following chronic oral dosing
Authors: Conklyn Maryrose , Andresen Catharine , Changelian Paul , Kudlacz Elizabeth
Published: September 2004

Janus kinase 3 (JAK3) is a cytoplasmic tyrosine kinase associated with the common γ chain, an integral component of cytokine receptors of the interleukin (IL)-2 family, including IL-4, -7, -9, -15, and -21. CP-690550 is a JAK3 inhibitor with immunosuppressive properties under development for transplantation. We evaluated alterations in circulating lymphocyte subsets in cynomolgus monkey blood following chronic (3-week), oral CP-690550 administration. Natural killer (NK) and CD8+ T cell numbers were reduced in a dose- and time-dependent manner; the latter was a primary effect on memory subsets. CD4+ T and B cell numbers were unaffected or slightly increased, respectively. NK cell numbers were reduced ∼80% (vs. 35% in vehicle-treated animals) and returned to baseline levels within 3 weeks following treatment cessation. CD8+ T cells declined by a maximum 43% (vs. 25% for vehicle-treated animals) but rebounded significantly (300%) within 2 weeks after the last dose. Although CP-690550 did not result in reduction of CD4+ T cell number, these cells also increased (225%) within 2 weeks of treatment cessation. IL-15 is important for maintaining homeostasis of these cell types, and CP-690550 inhibited IL-15-induced CD69 expression in NK cells [inhibitory concentration 50% (IC50)=48.0±8.4 nM] and CD8+ T cells (IC50=16.2±1.5 nM).
Differential macrophage expression of IL-12 and IL-23 upon innate immune activation defines rat autoimmune susceptibility
Authors: Andersson Åsa , Kokkola Riikka , Wefer Judit , Erlandsson-Harris Helena , Harris Robert A
Published: September 2004

Rodents typically demonstrate strain-specific susceptibilities to induced autoimmune models such as experimental arthritis and encephalomyelitis. A common feature of the local pathology of these diseases is an extensive infiltration of activated macrophages (MΦ). Different functional activation states can be induced in MΦ during innate immune activation, and it is this differential activation that might be important in susceptibility/resistance to induction or perpetuation of autoimmunity. In this study, we present an extensive, comparative analysis of the activation phenotypes of MΦ derived from autoimmune-susceptible and autoimmune-resistant rat strains to describe a cellular phenotype that defines the disease phenotype. We included investigation of receptor function, intracellular signaling pathways, cytokines, and other soluble mediators released after activation of cells using a panel of stimuli embracing many activation routes. We report that activation of MΦ from the autoimmune-susceptible strain was associated with alternative activation indicated by induction of arginase activity, a lower production of classical proinflammatory mediators, and a high production of interleukin (IL)-23, and MΦ from the autoimmune-resistant strains were associated with a higher production of proinflammatory mediators, a classical activation phenotype, and preferential induction of IL-12. These MΦ phenotypes thus reflect disparate, genetic cellular programs that define autoimmune susceptibility.
A hepatitis C virus-encoded, nonstructural protein (NS3) triggers dysfunction and apoptosis in lymphocytes: role of NADPH oxidase-derived oxygen radicals
Authors: Thorén Fredrik , Romero Ana , Lindh Magnus , Dahlgren Claes , Hellstrand Kristoffer
Published: September 2004

The persistent infection caused by hepatitis C virus (HCV) is presumably explained by a deficient immune response to the infection, but the basis for the inefficiency of immune-mediated virus eradication is not known in detail. This study addresses mechanisms of relevance to dysfunction of cytotoxic lymphocytes in HCV infection, with a focus on the role of phagocyte-derived oxygen radicals. We show that NS3, a nonstructural, HCV-encoded protein, induces a prolonged release of oxygen radicals from mononuclear and polymorphnuclear phagocytes by activating a key enzyme in radical formation, the reduced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. The NS3-activated phagocytes, in turn, induced dysfunction and/or apoptosis in three major subsets of lymphocytes of relevance to defense against HCV infection: CD3+/56– T cells, CD3–/56+ natural killer (NK) cells, and CD3+/56+ NKT cells. Two inhibitors of the NADPH oxidase, histamine and diphenylene iodonium, suppressed the NS3-induced oxygen radical production and efficiently protected lymphocytes against NS3-induced apoptosis and dysfunction. In conclusion, we propose that NS3, by triggering oxygen radical formation in phagocytes, may contribute to the dysfunction of antiviral lymphocytes in HCV-infected liver tissue and that strategies to circumvent oxidative stress may be useful in preventing HCV-associated carcinogenesis and facilitating lymphocyte-mediated clearance of infected cells.
Challenges and potential for linking tourism and agriculture to achieve pro-poor tourism objectives
Authors: Torres Rebecca , Momsen Janet Henshall
Published: September 2004

With tourism rapidly increasing in developing nations there is an emerging focus on integrating pro-poor tourism into both the international tourism and aid agendas. Following a brief review of the pro-poor tourism literature, this article argues for the explicit creation of tourism and agriculture linkages to achieve pro-poor tourism objectives. To understand both the potential and the problems associated with linking the two sectors, we present an in-depth case study of tourism and agriculture in Cancun, Mexico. The case study draws on the perspectives of Cancun hotel chefs, who control hotel food purchasing, and Quintana Roo farmers, who have attempted to supply the tourism industry, to provide a unique thorough examination of the challenges and potential for such linkages in a mass tourism resort.
Activin redux: specification of mesodermal pattern inXenopusby graded concentrations of endogenous activin B
Authors: Piepenburg Olaf , Grimmer Donna , Williams P. Huw , Smith James C.
Published: September 2004

Mesoderm formation in the amphibian embryo occurs through an inductive interaction in which cells of the vegetal hemisphere of the embryo act on overlying equatorial cells. The first candidate mesoderm-inducing factor to be identified was activin, a member of the transforming growth factor type βfamily, and it is now clear that members of this family are indeed involved in mesoderm and endoderm formation. In particular, Derrière and five nodal-related genes are all considered to be strong candidates for endogenous mesoderm-inducing agents. Here, we show that activin, the function of which in mesoderm induction has hitherto been unclear, also plays a role in mesoderm formation. Inhibition of activin function using antisense morpholino oligonucleotides interferes with mesoderm formation in a concentration-dependent manner and also changes the expression levels of other inducing agents such as Xnr2 and Derrière. This work reinstates activin as a key player in mesodermal patterning. It also emphasises the importance of checking for polymorphisms in the 5′untranslated region of the gene of interest when carrying out antisense morpholino experiments in Xenopus laevis.
Temporal requirement for hedgehog signaling in ventral telencephalic patterning
Authors: Fuccillo Marc , Rallu Murielle , McMahon Andrew P. , Fishell Gord
Published: September 2004

Hedgehog signaling is required for multiple aspects of brain development,including growth, the establishment of both dorsal and ventral midline patterning and the generation of specific cell types such as oligodendrocytes and interneurons. To identify more precisely when during development hedgehog signaling mediates these events, we directed the removal of hedgehog signaling within the brain by embryonic day 9 of development, using a FoxG1Cre driver line to mediate the removal of a conditional smoothened null allele. We observed a loss of ventral telencephalic patterning that appears to result from an initial lack of specification of these structures rather than by changes in proliferation or cell death. A further consequence of the removal of smoothened in these mice is the near absence of both oligodendrocytes and interneurons. Surprisingly,the dorsal midline appears to be patterned normally in these mutants. Together with previous analyses, the present results demonstrate that hedgehog signaling in the period between E9.0 and E12 is essential for the patterning of ventral regions and the generation of cell types that are thought to largely arise from them.
Potential role of protein tyrosine phosphatase nonreceptor type 13 in the control of oocyte meiotic maturation
Authors: Nedachi Taku , Conti Marco
Published: September 2004

Protein tyrosine phosphatase nonreceptor type 13 (PTPN13) is a tyrosine phosphatase with multiple interacting domains that has been implicated previously in the regulation of apoptosis. We provide evidence that PTPN13 plays an important role in the control of the meiotic cell cycle. A cDNA coding for PTPN13 was isolated during the screening for the substrate of protein kinase A expressed in mammalian oocytes. PTPN13 is expressed in both mouse and Xenopus oocytes and is a substrate for protein kinase A in vitro and in vivo. Expression of a truncated constitutively-active PTPN13 in Xenopus oocytes synergizes with progesterone in the induction of germinal vesicle breakdown, the translation of Mos, the phosphorylation of Erk and the dephosphorylation of Cdc2. The phosphatase activity of PTPN13 is required for this synergism. Oocyte injection with specific small interference RNA downregulates the expression of mRNA for PTPN13 and blocks oocyte maturation induced by progesterone, a blockade that can be overcome by Cdc25 overexpression. These findings indicate that PTPN13 is involved in the regulation of the meiotic cell cycle.
Activation and repression activities ofash2inDrosophilawing imaginal discs
Authors: Angulo Mireia , Corominas Montserrat , Serras Florenci
Published: September 2004

Polycomb (PcG) and trithorax (trxG) group genes are chromatin regulators involved in the maintenance of developmental decisions. Although their function as transcriptional regulators of homeotic genes has been well documented, little is known about their effect on other target genes or their role in other developmental processes. In this study, we have used the patterning of veins and interveins in the wing as a model with which to understand the function of the trxG gene ash2 (absent, small or homeotic discs 2). We show that ash2 is required to sustain the activation of the intervein-promoting genes net and blistered (bs) and to repress rhomboid(rho), a component of the EGF receptor (Egfr) pathway. Moreover, loss-of-function phenotypes of the Egfr pathway are suppressed by ash2 mutants, while gain-of-function phenotypes are enhanced. Our results also show that ash2 acts as a repressor of the vein L2-organising gene knirps (kni), whose expression is upregulated throughout the whole wing imaginal disc in ash2 mutants and mitotic clones. Furthermore, ash2-mediated inhibition of kni is independent of spalt-major and spalt-related. Together, these experiments indicate that ash2 plays a role in two processes during wing development: (1)maintaining intervein cell fate, either by activation of intervein genes or inhibition of vein differentiation genes; and (2) keeping kni in an off state in tissues beyond the L2 vein. We propose that the Ash2 complex provides a molecular framework for a mechanism required to maintain cellular identities in the wing development.
Role of p63 and basal cells in the prostate
Authors: Kurita Takeshi , Medina Roanna T. , Mills Alea A. , Cunha Gerald R.
Published: September 2004

The prostate contains two major epithelial cell types – luminal and basal cells - both of which develop from urogenital sinus epithelium. The cell linage relationship between these two epithelial types is not clear. Here we demonstrate that luminal cells can develop independently of basal cells, but that basal cells are essential for maintaining ductal integrity and the proper differentiation of luminal cells. Urogenital sinus (UGS) isolated from p63+/+ and p63–/– embryos developed into prostate when grafted into adult male nude mice. Prostatic tissue that developed in p63–/– UGS grafts contained neuroendocrine and luminal cells, but basal cells were absent. Therefore, p63 is essential for differentiation of basal cells, but p63 and thus basal cells are not required for differentiation of prostatic neuroendocrine and luminal epithelial cells. p63–/– prostatic grafts also contained atypical mucinous cells, which appeared to differentiate from luminal cells via activation of Src. In the response to castration, regression of p63–/– prostate was inordinately severe with almost complete loss of ducts, resulting in the formation of residual cystic structures devoid of epithelium. Therefore, basal cells play critical roles in maintaining ductal integrity and survival of luminal cells. However, regressed p63–/– prostate did regenerate in response to androgen administration, indicating that basal cells were not essential for prostatic regeneration.
Thebrinkergradient controls wing growth inDrosophila
Authors: Martín Francisco A. , Pérez-Garijo Ainhoa , Moreno Eduardo , Morata Ginés
Published: September 2004

The Decapentaplegic (Dpp) morphogen gradient controls growth and patterning in the Drosophila appendages. There is recent evidence indicating that the Dpp gradient is converted into an inverse gradient of activity of the gene brinker (brk), which encodes a transcriptional repressor and is negatively regulated by the Dpp pathway. We have studied how alterations in the Brk gradient affect the growth of the wing disc. We find that there is a negative correlation between brk activity and growth of the disc:high levels of brk prevent or reduce growth, whereas loss of brk activity results in excessive growth. This effect is concentration dependent: different amounts of Brk produce distinct rates of growth. Furthermore, our results demonstrate that although brk is able to induce apoptosis where there is a sharp difference in Brk levels, its role as a growth repressor is not achieved by inducing apoptosis but by reducing cell proliferation. Brk appears to downregulate the activity of genes that control cell proliferation, such as bantam.
PIN-FORMED1andPINOIDregulate boundary formation and cotyledon development inArabidopsisembryogenesis
Authors: Furutani Masahiko , Vernoux Teva , Traas Jan , Kato Takehide , Tasaka Masao , Aida Mitsuhiro
Published: September 2004

In dicotyledonous plants, two cotyledons are formed at bilaterally symmetric positions in the apical region of the embryo. Single mutations in the PIN-FORMED1 (PIN1) and PINOID (PID)genes, which mediate auxin-dependent organ formation, moderately disrupt the symmetric patterning of cotyledons. We report that the pin1 piddouble mutant displays a striking phenotype that completely lacks cotyledons and bilateral symmetry. In the double mutant embryo, the expression domains of CUP-SHAPED COTYLEDON1 (CUC1), CUC2 and SHOOT MERISTEMLESS (STM), the functions of which are normally required to repress growth at cotyledon boundaries, expand to the periphery and overlap with a cotyledon-specific marker, FILAMENTOUS FLOWER. Elimination of CUC1, CUC2 or STM activity leads to recovery of cotyledon growth in the double mutant, suggesting that the negative regulation of these boundary genes by PIN1 and PID is sufficient for primordium growth. We also show that PID mRNA is localized mainly to the boundaries of cotyledon primordia and early expression of PID mRNA is dependent on PIN1. Our results demonstrate the redundant roles of PIN1 and PID in the establishment of bilateral symmetry, as well as in the promotion of cotyledon outgrowth, the latter of which involves the negative regulation of CUC1, CUC2 and STM genes, which are boundary-specific downstream effectors.
Targeted deletion of the novel cytoplasmic dynein mD2LIC disrupts the embryonic organiser, formation of the body axes and specification of ventral cell fates
Authors: Rana Amer Ahmed , Barbera Juan Pedro Martinez , Rodriguez Tristan A. , Lynch Denise , Hirst Elizabeth , Smith James C. , Beddington Rosa S. P.
Published: September 2004

Dyneins have been implicated in left-right axis determination during embryonic development and in a variety of human genetic syndromes. In this paper, we study the recently discovered mouse dynein 2 light intermediate chain (mD2LIC), which is believed to be involved in retrograde intraflagella transport and which, like left-right dynein, is expressed in the node of the mouse embryo. Cells of the ventral node of mouse embryos lacking mD2LIC have an altered morphology and lack monocilia,and expression of Foxa2 and Shh in this structure is reduced or completely absent. At later stages, consistent with the absence of nodal cilia, mD2LIC is required for the establishment of the left-right axis and for normal expression of Nodal, and the ventral neural tube fails to express Shh, Foxa2 and Ebaf. mD2LIC also functions indirectly in the survival of anterior definitive endoderm and in the maintenance of the anterior neural ridge, probably through maintenance of Foxa2/Hnf3β expression. Together, our results indicate that mD2LIC is required to maintain or establish ventral cell fates and for correct signalling by the organiser and midline, and they identify the first embryonic function of a vertebrate cytoplasmic dynein.
Nerve regeneration and wound healing are stimulated and directed by an endogenous electrical field in vivo
Authors: Song Bing , Zhao Min , Forrester John , McCaig Colin
Published: September 2004

Biological roles for naturally occurring, extracellular physiological electric fields have been proposed over the past century. However, in the molecular era, many biologists presume that electric fields have little physiological relevance because there has been no unequivocal demonstration of their importance at the single-cell level in vivo. We have used an in vivo rat corneal model, which generates its own endogenous electric field and show that nerve sprouting, the direction of nerve growth and the rate of epithelial wound healing are controlled coordinately by the wound-induced electric field.
MAP kinases and cell migration
Authors: Huang Cai , Jacobson Ken , Schaller Michael D.
Published: September 2004

Recent studies have demonstrated that mitogen-activated protein kinases (MAPKs), including Jun N-terminus kinase (JNK), p38 and Erk, play crucial roles in cell migration. JNK, for example, regulates cell migration by phosphorylating paxillin, DCX, Jun and microtubule-associated proteins. Studies of p38 show that this MAPK modulates migration by phosphorylating MAPK-activated protein kinase 2/3 (MAPKAP 2/3), which appears to be important for directionality of migration. Erk governs cell movement by phosphorylating myosin light chain kinase (MLCK), calpain or FAK. Thus, the different kinases in the MAPK family all seem able to regulate cell migration but by distinct mechanisms.
Degradation of poly-L-lactide. Part 1: in vitro and in vivo physiological temperature degradation
Authors: Weir N A , Buchanan F J , Orr J F , Dickson G R
Published: September 2004

Poly-L-lactide (PLLA) is one of the most significant members of a group of polymers regarded as bioresorbable. The degradation of PLLA proceeds through hydrolysis of the ester linkage in the polymer's backbone and is influenced by the polymer's initial molecular weight and degree of crystallinity. To evaluate its degradation PLLA pellets were processed by compression moulding into tensile test specimens and by extrusion into 2 mm diameter lengths of rod, prior to being sterilized by ethylene oxide gas (EtO) and degraded in both in vitro and in vivo environments. On retrieval at predetermined time intervals, procedures were used to evaluate the material's molecular weight, crystallinity, mechanical strength, and thermal properties. Additionally, the in vivo host tissue's biological response was analysed. The results from this study suggest that in both the in vitro and in vivo environments, degradation proceeded at the same rate and followed the general sequence of aliphatic polyester degradation, ruling out enzymes contributing and accelerating the degradation rate in vivo. Additionally, the absence of cells marking an inflammatory response suggests that the PLLA rods investigated in vivo were biocompatible throughout the 44 weeks duration of the study, before any mass loss was observed.
A kinematic model of the wrist based on maximization of joint contact area
Authors: Sirkett D M , Mullineux G , Giddins G E B , Miles A W
Published: September 2004

The wrist is a complex joint and the factors governing its behaviour are poorly understood. A hypothesis that the movement of the carpal bones could be predicted using a minimum energy principle was tested. Carpal bones were dissected from a cadaveric forearm and their shapes were laser-digitized to obtain three-dimensional computer models. A computer program was created to measure contact area between neighbouring articular surfaces and to maximize this quantity by adjusting the six degrees of freedom of the bone models. This procedure was performed for 1.0° increments of rotation applied to the capitate bone up to 20° of ulnar and 10° of radial deviation. The model correctly predicted certain aspects of the complex behaviour of the carpal bones. The results for the scaphoid in particular displayed characteristics in common with known behaviour of this bone. During 20° of unlar deviation and 10° of radial deviation, the bone demonstrated 11.3° of extension and 9.4° of flexion respectively. The novelty of the study lay in the fact that the model did not rely upon ligamentous constraints. The results are encouraging, considering the only information used by the algorithm was the shape of the articular surfaces.
Degradation of poly-L-lactide. Part 2: Increased temperature accelerated degradation
Authors: Weir N A , Buchanan F J , Orr J F , Farrar D F , Dickson G R
Published: September 2004

Poly-L-lactide (PLLA) is one of the most significant members of a group of polymers regarded as bioresorbable. The degradation of PLLA proceeds through hydrolysis of the ester linkages in the polymer's backbone; however, the time for the complete resorption of orthopaedic devices manufactured from PLLA is known to be in excess of five years in a normal physiological environment. To evaluate the degradation of PLLA in an accelerated time period, PLLA pellets were processed by compression moulding into tensile test specimens, prior to being sterilized by ethylene oxide gas (EtO) and degraded in a phosphate-buffered solution (PBS) at both 50 °C and 70 °C. On retrieval, at predetermined time intervals, procedures were used to evaluate the material's molecular weight, crystallinity, mechanical strength, and thermal properties. The results from this study suggest that at both 50 °C and 70 °C, degradation proceeds by a very similar mechanism to that observed at 37 °C in vitro and in vivo. The degradation models developed also confirmed the dependence of mass loss, melting temperature, and glass transition temperature ( Tg) on the polymer's molecular weight throughout degradation. Although increased temperature appears to be a suitable method for accelerating the degradation of PLLA, relative to its physiological degradation rate, concerns still remain over the validity of testing above the polymer's Tg and the significance of autocatalysis at increased temperatures.
A finite element rheological model for polymethylmethacrylate flow: Analysis of the cement delivery in vertebroplasty
Authors: Baroud G , Yahia F B
Published: September 2004

Polymethylmethacrylate (PMMA) is increasingly used in orthopaedics. Finite element (FE) modelling can play an important role in understanding the PMMA flow behaviour. However, FE models have not been used so far because conventional FE packages do not allow for the rheopectic and pseudoplastic behaviour of PMMA to be taken into consideration and because it requires multiple expertise to incorporate these behaviours into an FE package. The objectives of the present paper are to: (a) propose a rheological model that describes PMMA flow behaviour; (b) implement this model into ANSYS using FORTRAN; and (c) validate the implementation by comparing it with analytical solutions. After the validation showed good agreement, an FE model of PMMA delivery through an eight-gauge cannula was developed to examine the extra-vertebral flow conditions of vertebroplasty. The FE analysis showed a logarithmic increase of the injection pressure, where it almost doubled from 1.2 to 2.3 MPa over two minutes. This unanticipated non-linear increase is due to the highly non-uniform viscosity profile in the cannula. It can be concluded that: (a) the rheological model implemented in ANSYS can be used to analyse practical flow problems related to PMMA and (b) time and shear-rate effects of PMMA are crucial to estimate its flow behaviour accurately.
A general elastohydrodynamic lubrication analysis of artificial hip joints employing a compliant layered socket under steady state rotation
Authors: Wang F C , Liu F , Jin Z M
Published: September 2004

A general numerical methodology was developed in the present study to analyse the elastohydrodynamic lubrication problem of a compliant layered socket against a rigid ball under steady state rotation representing flexion and extension during walking, with particular reference to artificial hip joint replacements. The general numerical methodology consisted of using the Newton-Raphson method to solve the Reynolds equation, simultaneously with the full elasticity equation using the finite element method in combination with the fast Fourier transform technique. Two specific types of acetabular cup were considered, one with ultra-high molecular weight polyethylene used in current total hip joint replacements, and one with polyurethane proposed for compliant layered ‘cushion form bearings’ for future developments. The film thickness and the pressure distribution for both cups were obtained under a wide range of operating conditions. The predicted central or average film thicknesses within the contact conjunction were compared with those estimated from various simplified theories available in the literature. A simple analytical methodology was consequently established to estimate the lubricating film thickness in a compliant layered socket, based on the corresponding ball-on-plane model and the consideration of the curvature effect.
Temperature prediction in a finite element model for sliding contact analysis of total hip prosthesis
Authors: Suhendra N , Stachowiak G W
Published: September 2004

A finite-element model for sliding contact in total hip joint prosthesis is presented in this paper. The hip prosthesis studied consists of an ultra-high molecular weight polyethylene (UHMWPE) acetabular cup articulating against cobalt-chrome and alumina-ceramic femoral heads. Various aspects of prosthesis operation were analysed using the finite-element model. For example, bulk material and surface stresses were analysed under varying conditions of elastic modulus, friction coefficient, sliding speed, and radial clearance. The resulting variations of temperature were also recorded. The results obtained from the model are useful in understanding the operating conditions and the causes of wear in the hip prosthesis.
The Bremen Cog of 1380 – An electron microscopic study of its degraded wood before and after stabilization with PEG
Authors: Hoffmann P. , Singh A. , Kim Y.S. , Wi S.G. , Kim I.-J. , Schmitt U.
Published: September 2004

The Bremen Cog is a big ship built AD 1380 from oak
wood. After its recovery from the river Weser, the water-logged
ship's timbers were successfully stabilized using
a novel two-step polyethylene glycol (PEG) treatment. An
electron microscopic study of the patterns of degradation
and of the distribution of PEG within the Cog wood
is described. Descriptions like these do not exist for
many well known archaeological objects. SEM revealed
that in areas with extensive degradation, wood cell walls
are thinned and cells have a distorted appearance. TEM
provided evidence that the wood has been degraded primarily
by erosion bacteria. The stabilization treatment
involved impregnation first with PEG 200 and then with
PEG 3000. The SEM observations of PEG-impregnated
wood revealed that in degraded tissues all cell types are
well filled with PEG 3000. Non-degraded tissues are
impermeable to PEG 3000 and are impregnated only with
PEG 200. SEM confirmed earlier fluorescence microscopic
evidence, that PEG 200 is absorbed by the cell
walls.
Ultrastructure of iodine treated wood
Authors: Donaldson L. , Frankland A.
Published: September 2004

Iodine staining has been used to study the orientation of cellulose microfibrils in wood using light microscopy. The aim of this work was to understand the exact nature of the staining reaction with iodine and to provide insight into the properties and organisation of the wood cell wall. Based on transmission electron microscopy it is apparent that precipitation of the iodine following treatment with nitric acid results in the formation of crystal cavities within the cell wall, which follow the orientation of the cellulose microfibrils. There is no evidence that iodine precipitates within “drying checks” as previously speculated. High resolution confocal reflectance microscopy of crystal cavity orientation indicates that the microfibril arrangement within pit borders can be both spiral and circular. Crystal cavities are much more abundant within the S1 layer than elsewhere. All of the cells examined had crystal cavities in the S1 region, which may be related to the reduced lignification at the S1/S2 boundary resulting in greater porosity of the cell wall at this location. Within the S2 region, clusters of crystal cavities are randomly distributed and occur in widely varying numbers among adjacent cell walls, suggesting variations in the porosity of the S2 wall within and among adjacent tracheids. Cavities form preferentially within more electron lucent regions of the cell wall. The random nature of crystal cavity formation within S2 clusters probably reflects the underlying random nature of the cell wall nanostructure. We conclude that iodine staining can provide important clues to the nanostructural properties of tracheid cell walls.