bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Electrostatic Field Intensity on Crystal Structure and Morphology of PVDF Fibers and Films
Authors: Zhang Hua , Ren Ping , Zhang Gui-Fang , Xiao Chang-Fa
Published: June 2006

Samples of melt-cast films and melt-spun poly(vinylidene fluoride) (PVDF) fibers were treated at various electrostatic field intensities. Their crystal structure and morphologies were investigated using wide-angle X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. The results showed that, the electrostatic field did not affect the crystal structure of PVDF fiber, but the crystal orientation was obviously changed. The crystals along the direction of electrostatic field became thick. The crystal orientation of the film, which was obtained by melting and crystallizing PVDF under an electrostatic field, was changed along the direction of electrostatic field. The crystal orientation was the same as the direction of the electrostatic field, but their structures were much more compact. The dipole moment was along the direction of the electrostatic field after the fiber or film had been treated in the electrostatic field
Processing and Properties of Carbon Fiber-reinforced PMR Type Polyimide Composites
Authors: Chen Jiansheng , Yang Shiyong , Tao Zhiqiang , Hu Aijun , Fan Lin
Published: June 2006

Carbon fiber-reinforced PMR-type polyimide composites were prepared from T-300 carbon fibers and polyimide matrix resin derived from 4,4′-methylenediamine (MDA), p-phenylenediamine ( p-PDA), diethyl ester of 3,3′,4,4′-oxydiphthalic acid (ODPE) and monoethyl ester of cis-5-norbornene-endo- 2,3-dicarboxylic acid (NE). The rheological properties of the PMR polyimide matrix resin were investigated. Based on this information, an optimized molding cycle was designed for fabricating T-300/PI composites. The composites exhibited high thermal stability and good mechanical properties. The glass transition temperature ( Tg) determined by dynamic mechanical analysis and the decomposition temperature at 5% of weight loss ( T5) were higher than 360 and 540°C, respectively. The flexural strength and shear strength of the composites were 1560 and 95 MPa, respectively. The composite also exhibited good thermal-oxidative stability and hygrothermal resistance as evaluated under the conditions of isothermal aginginairat320°C and hygrothermal aging at 120°C under 2 atm. The unaged thermal and mechanical properties of the composites were hardly changed after isothermal aging for 500 h and hygrothermal aging for 100 h. The scanning electron microscopic analyses for both the isothermally and hygrothermally aged composites revealed that the matrix was bonded to the fibers very well, implying that no interface degradation occurred during the aging experiments
Liberal Ends, Illiberal Means
Authors: Hartmann Betsy
Published: June 2006

The field of environmental security, and in particular Thomas Homer-Dixon's model of environmental conflict, were heavily influenced by neo-Malthusian degradation narratives, which disproportionately blame population pressures for generating poverty, environmental degradation, migration and political violence. In turn, the presence of these degradation narratives provided an avenue through which population actors and interests could intersect with the emerging environmental security agenda in the 1990s. As part of a political strategy to engage the foreign policy establishment in the 1994 UN Population Conference in Cairo, private population funders supported environmental conflict research and its dissemination at a variety of venues. There was a general willingness to deploy racially-charged demographic alarmism, particularly concerning population and migration, in the representation of Third World threats. The result was a kind of ideological schizophrenia within the population community as some actors used the politics of fear to generate support for the Cairo conference, while others appealed to a feminist agenda of women's empowerment and reproductive health. Some did both at the same time. This case illustrates the tension between liberal foreign policy goals and the illiberal means and ideologies deployed to achieve them, and the critical role played by private philanthropy. It is a cautionary tale with relevance today as certain population agencies are employing demographic explanations of terrorism to attract conservative support for international family planning assistance.
Rocking Stamper and Jumping Snakes from a Dynamical Systems Approach to Artificial Life
Authors: Der Ralf , Hesse Frank , Martius Georg
Published: June 2006

Dynamical systems offer intriguing possibilities as a substrate for the generation of behavior because of their rich behavioral complexity. However this complexity together with the largely covert relation between the parameters and the behavior of the agent is also the main hindrance in the goal oriented design of a behavior system. This paper presents a general approach to the self-regulation of dynamical systems so that the design problem is circumvented. We consider the controller (a neural net work) as the mediator for changes in the sensor values over time and define a dynamics for the parameters of the controller by maximizing the dynamical complexity of the sensorimotor loop under the condition that the consequences of the actions taken are still predictable. This very general principle is given a concrete mathematical formulation and is implemented in an extremely robust and versatile algorithm for the parameter dynamics of the controller. We consider two different applications, a mechanical device called the rocking stamper and the ODE simulations of a “snake” with five degrees of freedom. In these and many other examples studied we observed various behavior modes of high dynamical complexity
Structure and Dynamics of Random Recurrent Neural Networks
Authors: Berry Hugues , Quoy Mathias
Published: June 2006

Contrary to Hopfield-like networks, random recurrent neural networks (RRNN), where the couplings are random, exhibit complex dynamics (limit cycles, chaos). It is possible to store information in these networks through Hebbian learning. Eventually, learning “destroys” the dynamics and leads to a fixed point attractor. We investigate here the structural changes occurring in the network through learning. We show that a simple Hebbian learning rule organizes synaptic weight redistribution on the network from an initial homogeneous and random distribution to a heterogeneous one, where strong synaptic weights preferentially assemble in triangles. Hence learning organizes the network of the large synaptic weights as a “small-world” one
Mexico Inc.? Discourse Analysis and the Triumph of Managerialism
Authors: Hodge Bob , Coronado Gabriela
Published: June 2006

Multinational corporations have become players on the global stage, alongside nations. This article addresses one aspect of this development, the way leaders of nations now use discourses and ways of thinking formerly characteristic of business in major policy documents. The paper distinguishes different senses of ‘discourse’ to identify what is managerial discourse, using textbooks as data. It then looks at a specific instance, the Mexican Government’s ‘Plan-Puebla-Panama’, showing how it subordinates discourses of government to see Mexico as a commodity. Yet the contradictions this introduces act as an ideological complex, a functional set of contradictions implemented in dialogue.
New Places But Old Spaces: Knowledge Hierarchies Among Asian Small and Medium Size Enterprises Abroad
Authors: McNamara Dennis L.
Published: June 2006

Small and medium size enterprises (SMEs) play a critical role today in Asian regional production. However, their long-term viability depends on innovation drawing on local as well as global knowledge flows. In this paper, I ask whether firms moving to new production sites abroad have penetrated new spaces of information and knowledge. Japanese and Korean SMEs manufacturing abroad retain a static comparative advantage in sub-contracting for larger home country firms where accumulated knowledge is sufficient today for cost efficient production. They remain tied largely to knowledge hierarchies at home dominated by larger firms. Weak ties to the local business context abroad, however, deprive them of new learning advantages critical for flexible specialization. Lacking entrée to the learning environment of their offshore production sites, Asian SMEs often remain offshore factories rather than international firms participating in global learning environments. They find themselves in new geographical places but old cognitive spaces, confined to static rather than dynamic comparative advantage.
On the Ethics and Economics of Organized Citizenship
Authors: Leal Fernando
Published: June 2006

Nongovernmental organizations, charities and civil associations that purport to provide care, education and other ethical services without a profit motive represent themselves to the public as altruistically exercising citizenship. Their moral credentials seem impeccable. Yet many things are not what they appear to be, or what they should be, in what we may call ‘organized citizenship’. To follow the trail, we might make use of modern economics, whose recognition of ‘market failures’ has given way (via public choice theory) to the increasingly accepted reality of ‘government failure’. It may now be time to admit that there is also something like ‘civic failure’. For if all three sectors of society—business, government and civil organizations—are needed, they are also all imperfect.
Choices Parties Define
Authors: Budge Ian , McDonald Michael D.
Published: June 2006

Elections are the defining institution of democracy, in the sense of directly linking popular preferences to public policy. Which programme gets chosen depends on the outcome of the election. However, voters' choices are very much constrained by the policy packages parties put forward in the first place. In most representative elections, no alternatives can be voted on apart from those advocated by established parties, who thus play a role almost equal to electors in defining the election outcome. This article examines the policy choices offered by parties in their published programmes over 17 post-war democracies – uncovering a wide variety of patterns with only limited links to type of election system or number of parties. Voters always have a choice, though in some countries it is more limited and less nuanced than in others.
Party Membership and Campaign Activity in Britain
Authors: Fisher Justin , Denver David , Hands Gordon
Published: June 2006

The article examines the impact of electoral results on party membership and activity. Previous studies have focused on the long-term effects of electoral success or failure, suggesting that they may produce a spiral of demobilization or mobilization. The article shows that the dramatic change of electoral fortunes experienced by British parties at the 1997 general election broke this spiral, with the outcome leading to significant changes in the health and activity of local parties. It is concluded that dramatic election results can have significant implications for party organization.
Deriving international consensus on mentorship in doctoral education
Authors: Roy Callista , Linendoll Nadine M.
Published: June 2006

Global collaboration to address issues in nursing is essential in the twenty-first century. Given the importance of doctoral education in the development of nursing as a discipline, understanding mentoring in doctoral education is significant. The International Network for Doctoral Education in Nursing appointed a taskforce to define and describe the complex process of mentoring and to develop a position paper on mentoring in doctoral education. This paper describes this collaborative global project with the following aims: 1) to develop an international consensus paper on the complex process of mentoring to improve doctoral education worldwide and 2) to explicate activities that can enhance collaboration globally. Effective collaborative activities include the taskforce and the conference work, as well as the survey data collection. Collaborative activities were distributed across global regions. Multiple strategies of communication were used; however, face-to-face appears to be key. A high level of agreement was noted on the qualifications, responsibilities and expectations of a mentor. Some differences were found between countries in the area of a mentor’s role in accessing resources for students. Concluding recommendations are made for additional strategies to enhance the global participation in the final stages of the project and to assure that differences among countries are put into perspective
Tissue-specific expression of TRP channel genes in the mouse and its variation in three different mouse strains
Authors: Kunert-Keil Christiane , Bisping Frederike , Krüger Jana , Brinkmeier Heinrich
Published: June 2006

Background

The purpose of this work was to study the gene expression of transient receptor potential (TRP) channels in the mouse. The application of a standardized and quantitative technique, TaqMan RT-PCR, should give information about the pattern and relative importance of TRP channels for murine tissues and cell types. To verify data sets with an independent method, we studied the occurrence of some of the transcripts by in situ hybridization.

Results

We have characterized the mRNA expression of 22 TRP channels in the mouse with a focus on nerve and muscle tissues. This is the first study to describe the expression profiles of all channel isoforms of the four related Group 1 subfamilies (TRPC, TRPV, TRPM and TRPA) with a standardized and quantitative technique. Comparisons of transcript abundance showed a consistent dominance of TRPM7 and TRPC3 in most tissues. We further observed characteristic patterns and differences in gene expression of individual channels ranging over three orders of magnitude. The overall level of TRP channel mRNAs was highest in brain areas followed by kidney, lung, reproductive organs and muscle. In brain TRPM3 and TRPM7 dominated and 19 other isoforms were detected. In lung and kidney TRPV4, TRPV5 and TRPM7 were found in highest levels. TRPM7, TRPC3, TRPC6 and TRPM3 mRNAs were characteristically present in all tested muscle tissues. Most data obtained with the C57Bl/10 mouse strain were confirmed with Balb/c and NOD mice. However, TRPC3, C6, TRPM7, M3, TRPV2 and V4 expression showed marked differences in the three tested mouse strains. In situ hybridization revealed co-expression of transcripts on the cellular level and widely confirmed the data obtained with RT-PCR.

Conclusion

Transcripts coding for members of the TRPC, TRPV, TRPM and TRPA subfamilies of TRP cation channels are present in a broad spectrum of murine tissues. Several channel isoforms often coexist in a specific tissue or cell type. TRP channel expression does not show typical tissue specific dominance of individual members as is known from other ion channel families. Mouse strain specific variations of TRP channel expression indicate that genetic background or physiological requirements considerably influence expression levels.
Neural stem cells from protein tyrosine phosphatase sigma knockout mice generate an altered neuronal phenotype in culture
Authors: Kirkham David L , Pacey Laura KK , Axford Michelle M , Siu Roberta , Rotin Daniela , Doering Laurie C
Published: June 2006

Background

The LAR family Protein Tyrosine Phosphatase sigma (PTPσ) has been implicated in neuroendocrine and neuronal development, and shows strong expression in specific regions within the CNS, including the subventricular zone (SVZ). We established neural stem cell cultures, grown as neurospheres, from the SVZ of PTPσ knockout mice and sibling controls to determine if PTPσ influences the generation and the phenotype of the neuronal, astrocyte and oligodendrocyte cell lineages.

Results

The neurospheres from the knockout mice acquired heterogeneous developmental characteristics and they showed similar morphological characteristics to the age matched siblings. Although Ptprs expression decreases as a function of developmental age in vivo, it remains high with the continual renewal and passage of the neurospheres. Stem cells, progenitors and differentiated neurons, astrocytes and oligodendrocytes all express the gene. While no apparent differences were observed in developing neurospheres or in the astrocytes and oligodendrocytes from the PTPσ knockout mice, the neuronal migration patterns and neurites were altered when studied in culture. In particular, neurons migrated farther from the neurosphere centers and the neurite outgrowth exceeded the length of the neuronal processes from age matched sibling controls.

Conclusion

Our results imply a specific role for PTPσ in the neuronal lineage, particularly in the form of inhibitory influences on neurite outgrowth, and demonstrate a role for tyrosine phosphatases in neuronal stem cell differentiation.
Evaluation of CXCL9 and CXCL10 as circulating biomarkers of human cardiac allograft rejection
Authors: Karason Kristjan , Jernås Margareta , Hägg Daniel A , Svensson Per-Arne
Published: June 2006

Background

Cardiac allograft rejection remains a significant clinical problem in the early phase after heart transplantation and requires frequent surveillance with endomyocardial biopsy. However, this is an invasive procedure, which is unpleasant for the patient and carries a certain risk. Therefore, a sensitive non-invasive biomarker of acute rejection would be desirable.

Methods

Endomyocardial tissue samples and serum were obtained in connection with clinical biopsies from twenty consecutive heart transplant patients followed for six months. A rejection episode was observed in 14 patients (11 men and 3 women) and biopsies obtained before, during and after the episode were identified. Endomyocardial RNA, from three patients, matching these three points in time were analysed with DNA microarray. Genes showing up-regulation during rejection followed by normalization after the rejection episode were evaluated further with real-time RT-PCR. Finally, ELISA was performed to investigate whether change in gene-regulation during graft rejection was reflected in altered concentrations of the encoded protein in serum.

Results

Three potential cardiac allograft rejection biomarker genes, chemokine (C-X-C motif) ligand 9 (CXCL9), chemokine (C-X-C motif) ligand 10 (CXCL10) and Natriuretic peptide precursor A (NPPA), from the DNA microarray analysis were selected for further evaluation. CXCL9 was significantly upregulated during rejection (p < 0.05) and CXCL10 displayed a similar pattern without reaching statistical significance. Serum levels of CXCL9 and CXCL10 were measured by ELISA in samples from 10 patients before, during and after cardiac rejection. There were no changes in CXCL9 and CXCL10 serum concentrations during cardiac rejection. Both chemokines displayed large individual variations in the selected samples, but the serum levels between the two chemokines correlated (p < 0.001).

Conclusion

We conclude, that despite a distinct up-regulation of CXCL9 mRNA in human hearts during cardiac allograft rejection, this was not reflected in the serum levels of the encoded protein. Thus, in contrast to previous suggestions, serum CXCL9 does not appear to be a promising serum biomarker for cardiac allograft rejection.
Herbal medicine use during pregnancy in a group of Australian women
Authors: Forster Della A , Denning Angela , Wills Gemma , Bolger Melissa , McCarthy Elizabeth
Published: June 2006

Background

There are limited data on the extent of women's use of herbal medicines during pregnancy, despite the fact that knowledge of the potential benefits or harms of many of these products is sparse, particularly with respect to their use in pregnancy. We aimed to measure the prevalence of herbal medicine use in a group of pregnant women attending a public tertiary maternity hospital in Melbourne, Australia. Secondary aims were to explore why women took the herbal medicine, where they received advice, what form the supplements took and if they perceived the supplements to be helpful.

Methods

Consecutive pregnant women were approached in the antenatal clinic and the birth centre at around 36–38 weeks gestation. A questionnaire was developed and self-administered in English, as well as being translated into the four most common languages of women attending the hospital: Cantonese, Vietnamese, Turkish and Arabic. Back translation into English was undertaken by different professional translators to verify accuracy of both words and concepts. Data collected included demographic information, model of pregnancy care and herbal supplement use. Descriptive statistics were used initially, with stratified and regression analysis to compare sub-groups.

Results

Of 705 eligible women, 588 (83%) agreed to participate. Of these, 88 (15%) completed the questionnaire in a language other than English. Thirty-six percent of women took at least one herbal supplement during the current pregnancy. The most common supplements taken were raspberry leaf (14%), ginger (12%) and chamomile (11%). Women were more likely to take herbal supplements if they were older, tertiary educated, English speaking, non-smokers and primiparous.

Conclusion

Use of herbal supplements in pregnancy is likely to be relatively high and it is important to ascertain what supplements (if any) women are taking. Pregnancy care providers should be aware of the common herbal supplements used by women, and of the evidence regarding potential benefits or harm.
A methodology to estimate the potential to move inpatient to one day surgery
Authors: Gilliard Nicolas , Eggli Yves , Halfon Patricia
Published: June 2006

Background

The proportion of surgery performed as a day case varies greatly between countries. Low rates suggest a large growth potential in many countries. Measuring the potential development of one day surgery should be grounded on a comprehensive list of eligible procedures, based on a priori criteria, independent of local practices. We propose an algorithmic method, using only routinely available hospital data to identify surgical hospitalizations that could have been performed as one day treatment.

Methods

Moving inpatient surgery to one day surgery was considered feasible if at least one surgical intervention was eligible for one day surgery and if none of the following criteria were present: intervention or affection requiring an inpatient stay, patient transferred or died, and length of stay greater than four days. The eligibility of a procedure to be treated as a day case was mainly established on three a priori criteria: surgical access (endoscopic or not), the invasiveness of the procedure and the size of the operated organ. Few overrides of these criteria occurred when procedures were associated with risk of immediate complications, slow physiological recovery or pain treatment requiring hospital infrastructure. The algorithm was applied to a random sample of one million inpatient US stays and more than 600 thousand Swiss inpatient stays, in the year 2002.

Results

The validity of our method was demonstrated by the few discrepancies between the a priori criteria based list of eligible procedures, and a state list used for reimbursement purposes, the low proportion of hospitalizations eligible for one day care found in the US sample (4.9 versus 19.4% in the Swiss sample), and the distribution of the elective procedures found eligible in Swiss hospitals, well supported by the literature. There were large variations of the proportion of candidates for one day surgery among elective surgical hospitalizations between Swiss hospitals (3 to 45.3%).

Conclusion

The proposed approach allows the monitoring of the proportion of inpatient stay candidates for one day surgery. It could be used for infrastructure planning, resources negotiation and the surveillance of appropriate resource utilization.
Plasmodiumdiversity in non-malaria individuals from the Bioko Island in Equatorial Guinea (West Central-Africa)
Authors: Guerra-Neira Ana , Rubio José M , Royo Jesús Roche , Ortega Jorge Cano , Auñón Antonio Sarrión , Diaz Pedro Berzosa , LLanes Agustín Benito
Published: June 2006

Background

In this paper we analyse the Plasmodium sp. prevalence in three villages with different isolation status on the island of Bioko (Equatorial Guinea) where malaria is a hyper-endemic disease. We also describe the genetic diversity of P. falciparum, using several plasmodia proteins as markers which show a high degree of polymorphism (MSP-1 and MSP-2). The results obtained from three different populations are compared in order to establish the impact of human movements and interventions.

Methods

Plasmodium sp. were analysed in three villages on Bioko Island (Equatorial Guinea), one of which (Southern) is isolated by geographical barriers. The semi-nested multiplex polymerase chain reaction (PCR) technique was used to determine the prevalence of the four human plasmodia species. The genotyping and frequency of P. falciparum populations were determined by PCR assay target polymorphism regions of the merozoite surface proteins 1 and 2 genes (MSP-1 and MSP-2).

Results

The data obtained show that there are no differences in plasmodia population flow between the Northwest and Eastern regions as regards the prevalence of the different Plasmodium species. The Southern population, on the other hand, shows a minor presence of P. malariae and a higher prevalence of P. ovale, suggesting some kind of transmission isolated from the other two. The P. falciparum genotyping in the different regions points to a considerable allelic diversity in the parasite population on Bioko Island, although this is somewhat higher in the Southern region than the others. There was a correlation between parasitaemia levels and the age of the individual with the multiplicity of infection (MOI).

Conclusion

Results could be explained by the selection of particular MSP alleles. This would tend to limit diversity in the parasite population and leading up to the extinction of rare alleles. On the other hand, the parasite population in the isolated village has less outside influence and the diversity of P. falciparum is maintained higher. The knowledge of parasite populations and their relationships is necessary to study their implications for control intervention.
The p53-targeting human phosphatase hCdc14A interacts with the Cdk1/cyclin B complex and is differentially expressed in human cancers
Authors: Paulsen Michelle T , Starks Adrienne M , Derheimer Frederick A , Hanasoge Sheela , Li Liwu , Dixon Jack E , Ljungman Mats
Published: June 2006

Background

The evolutionary conserved cyclin-dependent kinase phosphatase hCdc14A has been shown to play potential roles in the regulation of mitotic exit and in the centrosome duplication cycle. We have recently shown that hCdc14A also can interact with the tumor suppressor p53 bothin vitroandin vivoand specifically dephosphorylates the ser315 site of p53in vitro. In this study we developed antibodies against hCdc14A to investigate the expression and regulation of hCdc14A in human tissues and cancer cells.

Results

We show that hCdc14A is differentially expressed in human tissues and in 75 cancer cell lines examined. Treatments with the histone deacetylase inhibitor TSA, the demethylating agent 5-aza-2'-deoxycytodine or the proteasome inhibitor MG132 significantly induced expression of hCdc14A in cell lines expressing low or undetectable levels of hCdc14A. There was a strong bias for low expression of hCdc14A in cancer cell lines harboring wild-type p53, suggesting that high Cdc14A expression is not compatible with wild-type p53 expression. We present evidence for a role for hCdc14A in the dephosphorylation of the ser315 site of p53in vivoand that hCdc14A forms a complex with Cdk1/cyclin B during interphase but not during mitosis.

Conclusion

Our results that hCdc14A is differentially expressed in human cancer cells and that hCdc14A can interact with both p53 and the Cdk1/cyclin B complex may implicate that dysregulation of hCdc14A expression may play a role in carcinogenesis.
Variation in fiberoptic bead-based oligonucleotide microarrays: dispersion characteristics among hybridization and biological replicate samples
Authors: Novak Jaroslav P , Miller Merrill C , Bell Douglas A
Published: June 2006

Background

Gene expression microarray technology continues to evolve and its use has expanded into all areas of biology. However, the high dimensionality of the data makes analysis a difficult challenge. Evaluating measurements and estimating the significance of the observed differences among samples remain important issues that must be addressed for each technology platform. In this work we use a consecutive sampling method to characterize the dispersion patterns of data generated from Illumina fiberoptic bead-based oligonucleotide arrays.

Results

To describe general properties of the dispersion we used a linear function SD = a + bYmean, approximating the standard deviation across arrays (Ymeanis the mean expression of a given consecutive sample). First we examined three levels of variability: 1) same cell culture, same reverse transcription, duplicate hybridizations; 2) same cell culture, reverse transcription replicates; 3) parallel cultures. Each higher level is expected to introduce a new source of variability. We observed minor differences in the constant term: the mean values are 3.5, 3.1 and 3.5, respectively. However, the mean coefficient b increased from 0.045 to 0.147 and 0.133. We compared the coefficients derived from the consecutive sampling to those obtained from the standard deviation of individual gene expressions and found them in good agreement. In the second experiment samples we detected 11 genes with systematically different expressions between the experiment samples treated with glucose oxidase and controls and corroborated the selection using the Mann-Whitney and other tests. We also compared the consecutive sampling and coincidence method to t-test: the average percentage of consistency was above 80 for the former and below 50 for the latter.

Conclusion

Our results indicate that the consecutive sampling method and standard deviation function provide a convenient description of the overall dispersion of Illumina arrays. We observed that the constant term of the standard deviation function is at average approximately the same for duplicate hybridization as for the assays with additional sources of variability. Furthermore, among the genes affected by glucose oxidase treatment we identified 6 genes in oxidative stress pathways and 5 genes involved in DNA repair. Finally, we noted that the consecutive sampling and coincidence test provide, under given conditions, more consistent results than the t-test.

Reviewers

This article was reviewed by Alexander Karpikov (nominated by MarkGerstein), Jordan King and Eugene V. Koonin.
Molluscs production associated to lunar-tide cycle: a case study in Paraíba State under ethnoecology viewpoint
Authors: Nishida Alberto K , Nordi Nivaldo , Alves Rômulo RN
Published: June 2006

Molluscs have been for a long time a very important food resource for humans. Therefore, oysters, clams, and mussels are highly required at seafood markets. Like any commercial food, it is necessary that molluscs present good quality standards, concerning some criteria such as amount of meat and appearance. In bivalves, condition index or fattening index is considered a satisfactory method for estimating the amount of meat related to the shell cavity. Molluscs gatherers of Paraíba State coast, northeastern Brazil, state that molluscan meat production increases during spring tide (designated by them as maré de lançamento) in opposition to the meat decrease which happens during neap tide (maré de quebramento) (they are designated technically in Portuguese as maré de sizígia and maré de quadratura, respectively). Weperformed a survey on the production of unha-de-velho or 'oldman'snail' (Tagelus plebeius) caught by molluscs gatherers in the estuary of River Paraíba do Norte, by observing locally their work, applying questionnaires, searching for a possible scientific relation of that molluscs condition to the gatherers empirical statement. Thus, we estimatedthe molluscs condition index through the method of solids percentage determination. We studied their work and the molluscs condition index during a full lunar-tide cycle. Determinations were carried out between 2nd September and 20th October, 1998, through 20 catches performed to obtain condition index from 400 bivalves. We observed that several biotic and abiotic ecological factors, namely reproduction cycle, biochemical components variations, animal size, and even parasitism, may affect the animal condition index. Despite this aspect, our present results confirmed a high overlapping (80%) of the condition index curve with lunar-tide cycle, in agreement with the gatherers statement. Although we recognize the need for formulating and testing other hypotheses, we consider a priori that the gatherers empirical assertion a unha tá gorda de acordocom a maré ('the "oldman's nail" is fat according to the tide', roughly translating) is justified by the observations here performed when the condition index increased during spring tide and decreased during neap tide.
Relaxin and β-estradiol modulate targeted matrix degradation in specific synovial joint fibrocartilages: progesterone prevents matrix loss
Authors: Hashem Gihan , Zhang Qin , Hayami Takayuki , Chen Jean , Wang Wei , Kapila Sunil
Published: June 2006

Relaxin, a 6-kDa polypeptide hormone, is a potent mediator of matrix turnover and contributes to the loss of collagen and glycosaminoglycans (GAGs) from reproductive tissues, including the fibrocartilaginous pubic symphysis of several species. This effect is often potentiated by β-estradiol. We postulated that relaxin and β-estradiol might similarly contribute to the enhanced degradation of matrices in fibrocartilaginous tissues from synovial joints, which may help explain the preponderance of diseases of specific fibrocartilaginous joints in women of reproductive age. The objective of this study was to compare the in vivo effects of relaxin, β-estradiol, and progesterone alone or in various combinations on GAG and collagen content of the rabbit temporomandibular joint (TMJ) disc fibrocartilage, knee meniscus fibrocartilage, knee articular cartilage, and the pubic symphysis. Sham-operated or ovariectomized female rabbits were administered β-estradiol (20 ng/kg body weight), progesterone (5 mg/kg), or saline intramuscularly. This was repeated 2 days later and followed by subcutaneous implantation of osmotic pumps containing relaxin (23.3 μg/kg) or saline. Tissues were retrieved 4 days later and analyzed for GAG and collagen. Serum relaxin levels were assayed using enzyme-linked immunosorbent assay. Relaxin administration resulted in a 30-fold significant (p < 0.0001) increase in median levels (range, approximately 38 to 58 pg/ml) of systemic relaxin. β-estradiol, relaxin, or β-estradiol + relaxin caused a significant loss of GAGs and collagen from the pubic symphysis and TMJ disc and of collagen from articular cartilage but not from the knee meniscus. Progesterone prevented relaxin- or β-estradiol-mediated loss of these molecules. The loss of GAGs and collagen caused by β-estradiol, relaxin, or β-estradiol + relaxin varied between tissues and was most prominent in pubic symphysis and TMJ disc fibrocartilages. The findings suggest that this targeted modulation of matrix loss by hormones may contribute selectively to degeneration of specific synovial joints.
Modelling geographically referenced survival data with a cure fraction
Authors: Cooner Freda , Banerjee Sudipto , McBean A Marshall
Published: June 2006

The emergence of geographical information systems and related softwares nowadays enables medical databases to incorporate the geographical information on patients, allowing studies in spatial associations. Public health administrators and researchers are often interested in detecting variation in survival patterns by region or county in order to understand the possible factors that contribute towards such spatial discrepancies. These issues have led statisticians to develop survival models that account for spatial clustering and variation. Additionally, with rapid developments in medical and health sciences, researchers increasingly encounter data sets where a substantial portion of patients are cured. Models accounting for cure in the population assist in the prognosis of potentially terminal diseases. This article proposes a Bayesian modelling framework that models spatial associations for areally referenced survival data using a general class of cure models proposed by Cooner et al. The special models we outline are alternatives to the traditional proportional hazards models and can be fitted using standard Bayesian software such as WinBUGS.
Spatio-temporal point processes, partial likelihood, foot and mouth disease
Authors: Diggle Peter J
Published: June 2006

Spatio-temporal point process data arise in many fields of application. An intuitively natural way to specify a model for a spatio-temporal point process is through its conditional intensity at location x and time t, given the history of the process up to time t. Often, this results in an analytically intractable likelihood. Likelihood-based inference then relies on Monte Carlo methods which are computationally intensive and require careful tuning to each application. A partial likelihood alternative is proposed, which is computationally straightforward and can be applied routinely. The method is applied to data from the 2001 foot and mouth epidemic in the UK, using a previously published model for the spatio-temporal spread of the disease.
βPIX controls cell motility and neurite extension by regulating the distribution of GIT1
Authors: Za Lorena , Albertinazzi Chiara , Paris Simona , Gagliani Mariacristina , Tacchetti Carlo , de Curtis Ivan
Published: June 2006

Cell motility entails the reorganization of the cytoskeleton and membrane trafficking for effective protrusion. GIT1/p95-APP1 is a member of a family of GTPase-activating proteins for ARF GTPases that affect endocytosis, adhesion and migration. GIT1 associates with paxillin and a complex including the Rac/Cdc42 exchanging factors PIX/Cool and the kinase PAK. In this study, we show that overexpression of βPIX induces the accumulation of endogenous and overexpressed GIT1 at large structures similar to those induced by an ArfGAP-defective mutant of GIT1 (p95-C2). Immunohistochemical analysis and immunoelectron microscopy reveal that these structures include the endogenous transferrin receptor. Time-lapse analysis during motogenic stimuli shows that the formation and perinuclear accumulation of the p95-C2-positive structures is paralleled by inhibition of lamellipodium formation and cell retraction. Both dimerization and a functional SH3 domain of βPIX are required for the accumulation of GIT1 in fibroblasts, which is prevented by the monomeric PIX-PG-ΔLZ. This mutant also prevents the formation of endocytic aggregates and inhibition of neurite outgrowth in retinal neurons expressing p95-C2. Our results indicate that βPIX is an important regulator of the subcellular distribution of GIT1, and suggest that alteration in the level of expression of the complex affects the endocytic compartment and cell motility.
Modulation of the PI 3-kinase–Akt signalling pathway by IGF-I and PTEN regulates the differentiation of neural stem/precursor cells
Authors: Otaegi Gaizka , Yusta-Boyo María J. , Vergaño-Vera Eva , Méndez-Gómez Héctor R. , Carrera Ana C. , Abad José L. , González Manuel , de la Rosa Enrique J. , Vicario-Abejón Carlos , de Pablo Flora
Published: June 2006

Neural stem cells depend on insulin-like growth factor I (IGF-I) for differentiation. We analysed how activation and inhibition of the PI 3-kinase–Akt signalling affects the number and differentiation of mouse olfactory bulb stem cells (OBSCs). Stimulation of the pathway with insulin and/or IGF-I, led to an increase in Akt phosphorylated on residues Ser473 and Thr308 (P-AktSer473 and P-AktThr308, respectively) in proliferating OBSCs, and in differentiating cells. Conversely, P-AktSer473 levels decreased by 50% in the OB of embryonic day 16.5-18.5 IGF-I knockout mouse embryos. Overexpression of PTEN, a negative regulator of the PI 3-kinase pathway, caused a reduction in the basal levels of P-AktSer473 and P-AktThr308 and a minor reduction in IGF-I-stimulated P-AktSer473. Although PTEN overexpression decreased the proportion of neurons and astrocytes in the absence of insulin/IGF-I, it did not alter the proliferation or survival of OBSCs. Accordingly, overexpression of a catalytically inactive PTEN mutant promoted OBSCs differentiation. Inhibition of PI 3-kinase by LY294002 produced strong and moderate reductions in IGF-I-stimulated P-AktSer473 and P-AktThr308, respectively. Consequently, LY294002 reduced the proliferation of OBSCs and the number of neurons and astrocytes, and also augmented cell death. These findings indicate that OBSC differentiation is more sensitive to lower basal levels of P-Akt than proliferation or death. By regulating P-Akt levels in opposite ways, IGF-I and PTEN contribute to the fine control of neurogenesis in the olfactory bulb.
Mitochondrial mechanisms of cold adaptation in cod (Gadus morhuaL.) populations from different climatic zones
Authors: Lucassen M. , Koschnick N. , Eckerle L. G. , Pörtner H.-O.
Published: June 2006

Adjustments in mitochondrial properties and capacities are crucial in acclimatization to seasonal cold as well as in evolutionary cold adaptation of marine ectotherms. To examine whether gene expression mechanisms contribute to different settings of aerobic capacities in populations of cod (Gadus morhua) along a latitudinal cline, maximum activities of key enzymes of mitochondrial metabolism and their respective mRNA levels were compared in white muscle and liver of cold (4°C) and warm (10°C) acclimated individuals from cod populations of the North Sea and the Barents Sea,respectively. In white muscle, cold acclimation caused a parallel increase in citrate synthase (CS) and in cytochrome c oxidase (COX) activities,but with a much larger effect in the cold eurythermal Arctic population. In liver, cold acclimation was accompanied by increments in CS activities, but differences between populations were minor. Overall COX activities in liver were not affected by cold acclimation, but were higher in the cold adapted population. In both populations increments in muscle CS capacities were tightly correlated with elevated mRNA levels, suggesting transcriptional control of citrate synthase levels in muscle. In liver, CS mRNA levels differed between populations but were not affected by cold acclimation, so that post-transcriptional control may contribute to elevated functional levels in this tissue. Mitochondrial-encoded COX2 mRNA levels were not limiting for functional activities in both tissues, in favour of post-transcriptional control or limitations by other transcripts of the COX complex. Altogether,the differentiation in gene expression between both populations was more strongly expressed at 4°C. The comparison of functional levels and transcript levels may reflect genetic differentiation at functional sites, in line with genetic differences between the two populations previously established by non-coding genetic markers.
2-hydroxyestradiol-17β-induced oocyte maturation: involvement of cAMP–protein kinase A and okadaic acid-sensitive protein phosphatases,and their interplay in oocyte maturation in the catfishHeteropneustes fossilis
Authors: Mishra A. , Joy K. P.
Published: June 2006

In Heteropneustes fossilis, in vitro incubation of postvitellogenic follicles with 2-hydroxyestradiol-17β(2-OHE2, 5 μmol l–1) decreased significantly the total cAMP level, concomitant with germinal vesicle breakdown (GVBD). The incubation of the follicles with cAMP or cAMP-elevating drugs[phosphodiesterase (PDE) inhibitors], such as IBMX(3-isobutyl-1-methyl-xanthine), theophylline and caffeine, inhibited the 2-OHE2-induced GVBD in a concentration-dependent manner. The magnitude of the response varied: both cAMP and IBMX were effective at all concentrations (0.1–2.0 mmol l–1), followed by theophylline (0.5–2.0 mmol l–1) and caffeine(1–2.0 mmol l–1). The protein kinase A (PKA) inhibitor H89 stimulated oocyte maturation in a concentration-dependent manner. However,when co-incubated with 2-OHE2 for 24 h it produced a biphasic effect: low concentrations (0.1 and 1.0 μmol l–1) did not alter the 2-OHE2-induced GVBD, but high concentrations (5 and 10μmol l–1) inhibited it. The incubation of the follicles with H89 lowered the inhibitory effect of IBMX on the 2-OHE2-induced GVBD. The incubation of the follicles with okadaic acid (OA), a protein phosphatase 1 and 2A inhibitor did not affect GVBD but when co-incubated with 2-OHE2, it enhanced the GVBD response. OA reversed the inhibitory effect of IBMX. The results suggest that OA may overcome the inhibition of 2-OHE2-induced GVBD by IBMX at a step distal to the cAMP–PKA pathway.
The origin of mean arterial and jugular venous blood pressures in giraffes
Authors: Mitchell Graham , Maloney Shane K. , Mitchell Duncan , Keegan D. James
Published: June 2006

Using a mechanical model of the giraffe neck and head circulation consisting of a rigid, ascending, `carotid' limb, a `cranial' circulation that could be rigid or collapsible, and a descending, `jugular' limb that also could be rigid or collapsible, we have analyzed the origin of the high arterial and venous pressures in giraffe, and whether blood flow is assisted by a siphon. When the tubes were rigid and the `jugular' limb exit was lower than the `carotid' limb entrance a siphon operated, `carotid' hydrostatic pressures became more negative, and flow was 3.3 l min–1 but ceased when the `cranial' and `jugular' limbs were collapsible or when the`jugular' limb was opened to the atmosphere. Pumping water through the model produced positive pressures in the `carotid' limb similar to those found in giraffe. Applying an external `tissue' pressure to the `jugular' tube during pump flow produced the typical pressures found in the jugular vein in giraffe. Constriction of the lowest, `jugular cuff', portion of the `jugular' limb showed that the cuff may augment the orthostatic reflex during head raising. Except when all tubes were rigid, pressures were unaffected by a siphon.

We conclude that mean arterial blood pressure in giraffes is a consequence of the hydrostatic pressure generated by the column of blood in the neck, that tissue pressure around the collapsible jugular vein produces the known jugular pressures, and that a siphon does not assist flow through the cranial circulation.
Partitioning locomotor energy use among and within muscles Muscle blood flow as a measure of muscle oxygen consumption
Authors: Marsh Richard L. , Ellerby David J.
Published: June 2006

Linking the mechanics and energetics of locomotion in vertebrates has been hampered by a lack of information regarding the energy use of individual skeletal muscles in vivo. Here, we present a review of the available data concerning the relationship between the rates of skeletal muscle blood flow and oxygen consumption(V̇O2). In active muscle, during aerobically supported exercise, there is a linear relationship between these variables, irrespective of the muscle fiber type and intensity of exercise through most of the aerobic exercise range. We conclude that the rate of blood flow is the best available indicator of aerobic metabolic rate in multiple individual muscles or regions of muscles during locomotion. The practical considerations of using the injectable microsphere technique to measure muscle blood flow in this context are discussed.