bluuebunny/crossref_metadata_2025 huggingface dataset:
Gender Identity and the Subject of Security
Authors: Hoogensen Gunhild , Rottem Svein Vigeland
Published: May 2004

This article is a contribution to the ongoing debate on human security in Security Dialogue; the authors argue that they provide an illustration of the complexity and dynamism of security. To illustrate this point, the authors examine security through the notion of societal security as understood by Ole Wæver, and use identity as a ‘door’ to a broader understanding and use of the concept of security. The focus of the article is gender identity as an integral perspective of security. In conjunction with elite-defined state interests, identity articulates the security interests of ‘significant groups’, supporting the articulation of security needs by individuals (as they identify themselves with various significant groups) and communities. Gender is identified as a ‘significant group’ relevant to the security dynamic. Using gender identity to understand security requires breaking down rigid and fundamental structures that have been built around traditional notions of security, allowing for articulations of security as it is understood by individuals in general and by women in particular.
The ‘New Wars’ Debate: A Historical Perspective is Needed
Authors: Newman Edward
Published: May 2004

In recent years, a number of analysts have argued that qualitative changes have occurred in the nature of violent conflict and that it is now possible to think in terms of ‘new wars’ that are distinct in significant ways from earlier forms of conflict. This article summarizes the different arguments of the ‘new wars’ thesis and argues that the distinction between ‘contemporary’ forms of conflict and wars of earlier times is exaggerated and in some instances does not stand up to scrutiny, especially when drawing upon historical material. In particular, the article questions the extent to which contemporary forms of organized violence reflect new patterns in terms of actors, objectives, spatial context, human impact, and the political economy and social structure of conflict. Moreover, the article argues that the tendency in the new wars scholarship to identify common patterns in ‘contemporary’ civil conflicts ignores important differences among them. In conclusion, the article considers the importance of recent scholarship on conflict for the security discourse and state sovereignty.
The Role of Gender of Children with Intellectual Disability and their Parents in Marital Intimacy in Southern India
Authors: Padencheri Seema , Russell Paul Swamidhas Sudhakar
Published: May 2004

In low-income countries where gender bias is prevalent, the gender of a child with intellectual disability may impair marital intimacy. This study explores that effect, together with gender differences in parental perceptions of marital intimacy. Twenty-three pairs of parents of children with intellectual disability were divided into two groups according to child gender. The Intimate Bond Measure was used to study the parents’ relationship. Intimacy between parents of girls with intellectual disability was significantly impaired compared with parents of boys with intellectual disability. Intimacy between parents continued to be impaired significantly after controlling for the confounding effect of challenging behaviours. Within the dyads, mothers and fathers did not significantly differ in perceived intimacy. This highlights the importance of assessing marital intimacy among parents of girls with intellectual disability, since impaired marital intimacy may be managed effectively with psychological interventions.
Needs of Chinese Parents of Children with Developmental Disability
Authors: Wong S. Y. , Wong Thomas K. S. , Martinson Ida , Lai Alice C. , Chen W. J. , He Y. S.
Published: May 2004

Parenting children with developmental disability requires specialized caring skills and knowledge. The aim of this study is to explore the experiences of Chinese parents in caring for these children. The focus group research approach was adopted. Twenty-three parents of children hospitalized with developmental disability from a Maternal and Children Hospital, Guangzhou, China participated in four focus group interviews. Validity of interpretation was ascertained. Inter-coder reliability was established with inter-coder agreement at 0.77. Data were fully transcribed, coded and analysed by content analysis. Eventually, five categories of needs were identified: parental, informational, attitude towards the child, coping and support. Parents needed to be equipped with practical parenting skills and information on developmental disability, and they needed to have realistic expectations for the child. They also needed professional support to cope with caring tasks and activities. Education is recommended as a fundamental strategy to enhance parents’ caring competency.
Identifying the Foci of Interest to Nurses in Irish Intellectual Disability Services
Authors: Sheerin Fintan
Published: May 2004

The role of nursing in intellectual disability services has not been constructively debated in the Republic of Ireland. The single report on such nursing in recent years retained a biomedical bias and was prepared within the context of staffing shortages. Intellectual disability nursing in Ireland is at a crucial juncture, with various forces seeking to relegate it to a postgraduate specialist subject. The specific input of intellectual disability nursing to the broader profession may be lost, and may be subsumed within an illness model unrepresentative of the reality of care. The purpose of this study was to explore this specific input and to identify foci for nursing intervention within residential intellectual disability care. This was achieved through a Delphi study; three focus groups held among Irish intellectual disability nurses working in three service settings; and personal interviews held with residential service/nurse managers.
Using Workshops on Loss for Adults with Learning Disabilities
Authors: Read Sue , Papakosta-Harvey Vicky
Published: May 2004

This article is the second in a series that catalogues the experiences of both facilitators and participants involved in a group work opportunity to explore loss and change for 10 adults with learning disabilities. Building upon previous research, the article discusses general issues surrounding loss and change and introduces group work as a vehicle that promotes learning. The rationale inherent in developing and establishing the group is explained, and the methods and procedures used within a qualitative framework to evaluate the group work are introduced. Key emerging themes include issues surrounding the importance of group facilitation (such as boundaries and endings); the diverse loss responses experienced by participants; the powerful stories of loss evoked and associated coping strategies; and how group work can be a powerful medium for learning.
Anti-GPVI–associated ITP: an acquired platelet disorder caused by autoantibody-mediated clearance of the GPVI/FcRγ-chain complex from the human platelet surface
Authors: Boylan Brian , Chen Hong , Rathore Vipul , Paddock Cathy , Salacz Michael , Friedman Kenneth D. , Curtis Brian R. , Stapleton Michelle , Newman Debra K. , Kahn Mark L. , Newman Peter J.
Published: May 2004

Platelet glycoprotein (GP) VI is a 62-kDa membrane glycoprotein that exists on both human and murine platelets in a noncovalent complex with the Fc receptor (FcR) γ chain. The GPVI/FcRγ-chain complex serves as the major activating receptor for collagen, as evidenced by observations that platelets genetically deficient in GPVI or the FcRγ chain are highly refractory to collagen-induced platelet activation. Recently, several different rat anti–murine GPVI monoclonal antibodies, termed JAQs 1, 2, and 3, were produced that had the unique property of “immunodepleting” GPVI from the murine platelet surface and rendering it unresponsive to collagen or GPVI-specific agonists like convulxin or collagen-related peptide (CRP). Herein, we describe a patient with a mild bleeding disorder and a moderately reduced platelet count whose platelets fail to become activated in response to collagen or CRP and inefficiently adhere to and form thrombi on immobilized collagen under conditions of arterial shear. Although the amount of GPVI platelet mRNA and the nucleotide sequence of the GPVI gene were found to be normal, both GPVI and the FcRγ chain were nearly absent from the platelet surface and were markedly reduced in wholeplatelet detergent lysates. Patient plasma contained an autoantibody that bound specifically to GPVI-positive, normal platelets, and cleared soluble GPVI from the plasma, suggesting that the patient suffers from a rare form of idiopathic thrombocytopenic purpura caused by a GPVI-specific autoantibody that mediates clearance of the GPVI/FcRγ-chain complex from the platelet surface. Since antibody-induced GPVI shedding now has been demonstrated in both humans and mice, these studies may provide a rationale for developing therapeutic reagents that induce temporary depletion of GPVI for the treatment of clinical thrombosis.
Intima-media thickness: indicator of cardiovascular risk and measure of the extent of atherosclerosis
Authors: Poredos Pavel
Published: May 2004

The measurement of intima-media thickness (IMT) of large superficial arteries, especially the carotid, using high-resolution B-mode ultrasonography has emerged as one of the methods of choice for determining the anatomic extent of atherosclerosis and for assessing cardiovascular risk. IMT measurement obtained by ultrasonography correlates very well with pathohistologic measurements and the reproducibility of this technique is good. Population studies have shown a strong correlation between carotid IMT and several cardiovascular risk factors, and it has also been found to be associated with the extent of atherosclerosis and end-organ damage of high-risk patients. Therefore, increased carotid IMT is a measure of athero-sclerotic burden and a predictor of subsequent events. Because of its quantitative value, carotid IMT measurement is more and more frequently used in clinical trials to test the effects of different preventive measures, including drugs. More recently, there has been interest in the clinical use of this technique for detecting preclinical (asymptomatic) atherosclerosis and for identifying subjects at high risk. Measurement of carotid IMT could influence a clinician to intervene with medication and to use more aggressive treatment of risk factors in primary prevention, and in patients with atherosclerotic disease in whom there is evidence of progression and extension of atherosclerotic disease. For more extensive use of this method in clinical practice a consensus concerning the standardization of methods of measurement and precise definition of threshold between normal and pathologic IMT value is urgently needed.
The metabolic syndrome: an emerging risk state for cardiovascular disease
Authors: Prabhakaran Dorairaj , Anand Sonia S
Published: May 2004

The common clustering of glucose intolerance, insulin resistance, abdominal adiposity, elevated blood pressure, and low HDL cholesterol is referred to as metabolic syndrome. Individuals with this syndrome have an increased risk of developing cardiovascular disease (CVD). The World Health Organisation and the National Cholesterol Education Programme’s Adult Treatment Panel III (NCEP-ATP III) have outlined specific diagnostic criteria for the diagnosis of the metabolic syndrome to help in the Identification of this syndrome in clinical practice. While the WHO criteria were specifically developed for use in research, the NCEP criteria are useful in clinical diagnosis of the metabolic syndrome. The metabolic syndrome is amenable to lifestyle modifications such as increased physical activity, weight loss, and possibly intake of low-glycemic foods. Drug therapy may be used to treat individual components of the syndrome such as elevated blood pressure and dyslipidemia. To control elevated glucose levels (when there is failure of lifestyle modification), medications such as metformin, thiazolidinedione derivatives and alpha glucosidase inhibitors may be used.
Superficial venous thrombosis of the lower extremities: analysis of risk factors, and recurrence and role of anticoagulation
Authors: Gorty Satya , Patton-Adkins Jeanne , DaLanno Michelle , Starr Jean , Dean Steven , Satiani Bhagwan
Published: May 2004

Superficial venous thrombosis (SVT) of the lower extremities is a common ailment seen in outpatient offices of vascular medicine and surgery practices. This study of 60 consecutive outpatients was carried out to examine the incidence of concomitant deep venous thrombosis (DVT), risk factors associated with SVT, recurrence of SVT and=or new DVT, and the role of anticoagulant therapy in the prevention of recurrence. Concomitant SVT and DVT (13%) were significantly less likely to be present in patients with varicose veins as compared to patients without varicose veins (p < 0.04) and more likely to be present in patients with a previous history of DVT (p < 0.02). Fifteen patients (25%) developed either recurrent SVT or new DVT, with two patients developing both SVT and DVT. The absence of varicose veins and the presence of a hypercoagulable condition (n = 12) appeared to influence the development of new DVT but not the recurrence of SVT. Recurrent SVT was much more likely in patients with thrombosis of the tributaries (p < 0.0008). New DVT was seen significantly less frequently in patients on anticoagulants (p < 0.02).
Randomized trial of AT-1015 for treatment of intermittent claudication. A novel 5-hydroxytryptamine antagonist with no evidence of efficacy
Authors: Hiatt William R , Hirsch Alan T , Cooke John P , Olin Jeffrey W , Brater D Craig , Creager Mark A
Published: May 2004

AT-1015 is a novel selective 5-HT2A serotonin receptor antagonist that is known to impair platelet aggregation and vasoconstriction. Serotonin has been hypothesized to contribute to claudication symptoms in individuals with peripheral arterial disease (PAD) via micro-vascular vasoconstrictor and thrombotic effects. AT-1015 was thus evaluated in 439 patients with claudication who were randomized in a double-blind, placebo-controlled trial comparing 10 mg, 20mg, and 40 mg BID versus placebo for 24 weeks. Treadmill walking performance was assessed by peak walking time (PWT) and pain-free walking time (PFWT). Quality of life (QoL) was measured by the Walking Impairment Questionnaire (WIQ) and the Health Status Survey SF-36. Limb hemodynamics was assessed with the ankle-brachial index (ABI). The 40 mg arm was terminated prematurely by recommendation of the Data Safety Monitoring Committee due to an excess number of non-fatal myocardial infarctions. At study conclusion, there were no statistically significant differences in the mean change of PWT, PFWT, ABI and QoL between the 10 mg and 20 mg BID treatment groups compared with placebo. The proportion of patients who experienced an adverse event (AE) was similar across all treatment groups. Antimuscarinic and gastrointestinal AEs were more common in the AT-1015 treatment groups. Two deaths occurred: one in the placebo group and the other in the AT-1015 20 mg group. Although a prolongation of the QTc interval was observed in all groups, this was not clinically significant (QTc > 500ms). Mean supine pulse rates were significantly increased in all AT-1015 treatment groups, consistent with predicted antimuscarinic effects. Population pharmacokinetic analysis fit a one-compartment model with first-order absorption and elimination. These data indicate that selective serotonin receptor blockade does not improve exercise tolerance or quality of life in individuals with claudication.
Adaptation of the endothelium to fluid flow: in vitro analyses of gene expression and in vivo implications
Authors: Wasserman Scott M , Topper James N
Published: May 2004

Biomechanical forces generated by blood flow play an important role in the pathogenesis of vascular disease. For example, regions exposed to non-uniform shear stresses develop early atherosclerotic lesions while areas exposed to uniform shear stresses are protected. A variety of in vitro flow apparatuses have been created to apply well-characterized flow patterns to endothelial cells in an effort to dissect the cellular and molecular pathways involved in these distinct processes. Recent advances in biotechnology have permitted large-scale transcriptional profiling techniques to replace candidate gene screens and have allowed the genome-wide examination of biomechanical force-induced endothelial gene expression profiles. This review provides an overview of biomechanical force-induced modulation of endothelial phenotype. It examines the effect of sustained laminar shear stress (LSS), a type of uniform shear stress, on in vitro endothelial gene expression by synthesizing data from the early candidate gene and differential display polymerase chain reaction (PCR) approaches to the numerous, recent, high throughput functional genomic analyses. These studies demonstrate that prolonged LSS regulates the expression of only a small percentage (1-5%) of endothelial genes, and this transcriptional profile produces an endothelial phenotype that is quiescent, being protected from apoptosis, inflammation and oxidative stress. These observations provide a possible molecular mechanism for the strong correlation between patterns of blood flow and the occurrence of vascular pathologies, such as atherosclerosis, in vivo.
Effect of contrast enhancement on measurement of carotid artery intimal medial thickness
Authors: Macioch James E , Katsamakis C Dean , Robin Jason , Liebson Philip R , Meyer Peter M , Geohas Chris , Raichlen Joel S , Davidson Michael H , Feinstein Steven B
Published: May 2004

Previous studies have used standard B-mode ultrasound to quantify the aggregate mean intimal medial thickness (IMT) of the near and far wall of the common carotid artery (CCA). Many investigators have had difficulty in accurately evaluating the near wall IMT secondary to difficulty in discerning the vessel lumen and intima. The purpose of this study is to determine the effect of contrast enhanced ultrasound on IMT measurement when compared with non-enhanced images. Twenty-six patients who had standard carotid ultrasounds completed over a 6-month period were evaluated, with 24 imaged by the same sonographer. Five to six measurements of the near and far walls were obtained over a 1 cm distance, beginning and ending 0.5 cm and 1.5 cm proximal to the carotid bifurcation. The measurements were made with and without the contrast agent OptisonTM (perflutren protein type-A microspheres), which was given as an IV bolus (0.5-0.7 cc). Of those imaged by the same sonographer, 40 carotid arteries were examined and a total of 867 measurements were obtained. A total of 10% of the carotid ultrasounds were restudied approximately 1 month after the initial interpretation to assess observer accuracy. The near wall CCA mean (SD) IMT was 0.075 (0.019)cm for left with contrast versus 0.067 (0.023)cm for left without contrast and 0.089 (0.024)cm for right with versus 0.071 (0.022)cm for right without, p 0.0001 both sides. For the far wall of the CCA, the mean (SD) IMT comparison was 0.075 (0.021)cm for left with versus 0.070 (0.016)cm for left without, p = 0.005, and 0.070 (0.023)cm for right with versus 0.070 (0.016) cm for right without, p = 0.68. In conclusion, contrast-enhanced IMT measurement showed a highly statistically significant difference in near carotid wall thickness determinations versus non-contrast values. The thicker measurement is in agreement with previously reported data showing that non-contrast images underestimated near wall common carotid IMT in histologic samples.
Ischemic stroke in patients with intermittent claudication: a clinical study of 142 cases
Authors: Arboix Adrià , Tarruella Marc , García-Eroles Lluis , Oliveres Montserrat , Miquel Carles , Balcells Miquel , Targa Cecilia
Published: May 2004

The clinical features, risk factors, neuroimaging findings, and outcome of acute ischemic stroke were assessed in patients with intermittent claudication. Data from 142 patients with ischemic stroke and intermittent claudication were collected from a prospective hospital-based stroke registry in which 2500 consecutive acute stroke patients attended over a 12-year period. Ischemic stroke in patients with intermittent claudication accounted for 7.7% of all ischemic strokes (n = 1840). Ischemic stroke with and without intermittent claudication showed a similar in-hospital mortality rate (16% vs 14%) and absence of functional limitation at hospital discharge (20.5% vs 18.5%). Ischemic stroke patients with intermittent claudication showed a significantly shorter length of stay than patients without symptomatic peripheral arterial disease (14.6 vs 18.8 days, p < 0.05). Ischemic heart disease, transient ischemic attack (TIA), renal dysfunction, and watershed infarct were significant independent predictors of ischemic stroke in patients with intermittent claudication. Although cerebral infarction in patients with intermittent claudication showed a clinical profile suggestive of poor outcome, the prognosis was similar to that of ischemic stroke without intermittent claudication.
Maximizing power and minimizing treatment failures in clinical trials
Authors: Rosenberger William F , Hu Feifang
Published: May 2004

Background Response-adaptive randomization procedures have a long history in the theoretical statistics literature over the past four decades. The main idea historically was to develop randomization procedures that place fewer patients on the inferior treatment. More recent research has changed the main focus to that of usual considerations in typical clinical trials: power, sample size, expected treatment failures, maintaining randomization, among others.

Methods We describe response-adaptive randomization procedures for simple clinical trials comparing two binomial success probabilities, including the randomized play-the-winner rule, the drop-the-loser rule, and a modification of the doubly-adaptive biased coin design. We treat as our principal goal minimizing expected treatment failures while preserving power and randomization. Based on some recent theoretical literature [1,8,14], the basic guidelines for selecting an appropriate procedure include targeting optimal allocation, having small variability, and preserving randomization. We use simulation to compare power and expected treatment failures according to these guidelines.

Results When the two treatments had high probabilities (>0.5) of success, the randomized play-the-winner rule was less powerful than complete randomization and the drop-the-loser rule by 1–3 percent with slightly larger expected number of treatment failures than the drop-the-loser rule. For all the success probabilities we examined, the drop-the-loser rule was within 1 percent of the power of complete randomization with a modest reduction of treatment failures. The doubly-adaptive biased coin design was as powerful or slightly more powerful than complete randomization in every case and expected treatment failures were always less, with modest reductions of the order of 0.3 percent to 8.3 percent.

Conclusions We conclude that the drop-the-loser rule and a modification of the doubly-adaptive biased coin design are the preferred procedures, and simulations show that these procedures yield a modest reduction in expected treatment failures while preserving power over complete randomization.
Equipoise: a case study of the views of clinicians involved in two neonatal trials
Authors: Garcia Jo , Elbourne Diana , Snowdon Claire
Published: May 2004

Background It is considered to be a fundamental ethical premise of human experimentation, that it should be carried out only where the effects of an intervention are unclear. The point at which it is considered that there is insufficient scientific and medical evidence to clearly state the superiority of an intervention has been termed equipoise. This concept has been the subject of much recent impassioned debate but little empirical research about the views of people involved in recruitment to randomized controlled trials (RCTs), and none in the particularly emotive area of neonatal intensive care.

Methods Thirty neonatologists recruiting into one or both of two neonatal RCTs in five centres in England were interviewed using a semi-structured schedule to explore their involvement in randomised trials. The interviews were tape-recorded and transcribed. Equipoise was one among a range of topics covered. Concepts relating to equipoise were identified by close reading of the entire interviews. Themes emerging from the data were noted in their contexts then discussed between the coauthors. Interviewees also completed a brief questionnaire about their demographic background, and their experience of research and RCTs.

Results Almost all the neonatologists used the concept of equipoise [using words and phrases such as uncertainty, lack of knowledge (or ignorance), strengths of views, and balancing of pros and cons] in their interview and, for most of them, equipoise seemed to be a useful term. They explored ideas about equipoise at the individual and community levels, and some linked equipoise with notions of the responsibility that should be exercised by the scientific and professional communities. They differed in the importance they gave to individual equipoise, and in how they reacted to threats to equipoise. Feelings of doubt about a trial and disturbed equipoise were more often expressed by more junior doctors.

Conclusions Our findings suggest that the concept of equipoise goes beyond the idea of uncertainty. In part this is because it includes the balancing of benefit and harm; this balancing is part of a professional obligation and requires engagement with ‘expert’ knowledge. Equipoise could therefore be seen as ‘active’ or ‘responsible’ uncertainty. Elucidation of this difficult concept may help to facilitate recruitment for both clinicians and parents in future trials and thereby help to find answers to important clinical questions.
Matrix-mediated canal formation in primmorphs from the sponge Suberites domuncula involves the expression of a CD36 receptor-ligand system
Authors: Müller Werner E. G. , Thakur Narsinh L. , Ushijima Hiroshi , Thakur Archana N. , Krasko Anatoli , Le Pennec Gaël , Indap Madhavi M. , Perović-Ottstadt Sanja , Schröder Heinz C. , Lang Gerhard , Bringmann Gerhard
Published: May 2004

Sponges (Porifera), represent the phylogenetically oldest metazoan phylum still extant today. Recently, molecular biological studies provided compelling evidence that these animals share basic receptor/ligand systems, especially those involved in bodyplan formation and in immune recognition, with the higher metazoan phyla. An in vitro cell/organ-like culture system, the primmorphs, has been established that consists of proliferating and differentiating cells, but no canals of the aquiferous system. We show that after the transfer of primmorphs from the demosponge Suberites domuncula to a homologous matrix (galectin), canal-like structures are formed in these 3D-cell aggregates. In parallel with the formation of these structures a gene is expressed whose deduced protein falls into the CD36/LIMPII receptor family. The receptor was cloned and found to be strongly expressed after adhesion to the galectin matrix. This process was suppressed if primmorphs were co-incubated with a homologous polypeptide containing the CSVTCG domain, as found in thrombospondin-1 (and related) molecules of vertebrates. In situ hybridization studies revealed that the S. domuncula CD36/LIMPII receptor is localized in the pinacocytes that surround the canals of the sponge. Furthermore, a secondary metabolite from a sponge-associated bacterium was isolated and characterized, the 2-methylthio-1,4-naphthoquinone (MTN). MTN causes inhibition of cell proliferation of vertebrate tumor cells at concentrations of >80 ng/ml. However, doses of only 2 ng are required to potently inhibit angiogenesis in the chick chorio-allantoic membrane assay. At concentrations of 10 ng/ml this compound was also found to suppress the expression of the S. domuncula CD36/LIMPII; this result is a first indication that this secondary metabolite has a conserved functional activity: the suppression of the formation of the circulation system, from sponges to vertebrates.
Distinct kinetic and mechanical properties govern selectin-leukocyte interactions
Authors: Hanley William D. , Wirtz Denis , Konstantopoulos Konstantinos
Published: May 2004

Leukocytes are recruited from the bloodstream to sites of inflammation by the selectin family of adhesion receptors. In vivo and in vitro studies reveal distinctive rolling velocities of polymorphonuclear leukocytes over E-, P- and L-selectin substrates. The kinetic and mechanical properties of the selectin-ligand bonds responsible for these differences at the single-molecule level are not well understood. Using single-molecule force spectroscopy, we probe in situ the rupture force, unstressed off-rate and reactive compliance of single selectin receptors to single ligands on whole human polymorphonuclear leukocytes (PMNs) under conditions that preserve the proper orientation and post-translational modifications of the selectin ligands. Single L-selectin bonds to PMNs were more labile than either E- or P-selectin in the presence of an applied force. This outcome, along with a higher unstressed off-rate and a higher reactive compliance, explain the faster L-selectin-mediated rolling. By quantifying binding frequency in the presence of a specific blocking monoclonal antibody or following enzyme treatment, we determined that P-selectin glycoprotein ligand-1 is a high-affinity ligand for E-selectin on PMNs under force. The rupture force spectra and corresponding unstressed off-rate and reactive compliance of selectin-ligand bonds provide mechanistic insights that might help to explain the variable rolling of leukocytes over different selectin substrates.
Endoplasmic reticulum stress-induced programmed cell death in soybean cells
Authors: Zuppini Anna , Navazio Lorella , Mariani Paola
Published: May 2004

In animal cells, the endoplasmic reticulum may participate in programmed cell death by sensing and transducing apoptotic signals. In an attempt to analyze the role of the endoplasmic reticulum in plant programmed cell death we investigated the effect of cyclopiazonic acid, a specific blocker of plant endoplasmic reticulum-type IIA Ca2+-pumps, in soybean cells. Cyclopiazonic acid treatment elicited endoplasmic reticulum stress and a biphasic increase in cytosolic Ca2+ concentration, followed by the induction of a cell death program. Cyclopiazonic acid-induced programmed cell death occurred with accumulation of H2O2, cytochrome c release from mitochondria, caspase 9- and caspase 3-like protease activation, cytoplasmic shrinkage and chromatin condensation. Chelation of cytosolic Ca2+ with 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid (acetoxymethil ester) failed to inhibit cyclopiazonic acid-induced cell death. Taken together, our results provide evidence for a role of the endoplasmic reticulum and mitochondria in regulating cyclopiazonic acid-induced programmed cell death in soybean cells, probably via a cross-talk between the two organelles.
Mechanosensitive ion channels: molecules of mechanotransduction
Authors: Martinac Boris
Published: May 2004

Cells respond to a wide variety of mechanical stimuli, ranging from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. The cell membrane presents a major target of the external mechanical forces that act upon a cell, and mechanosensitive (MS) ion channels play a crucial role in the physiology of mechanotransduction. These detect and transduce external mechanical forces into electrical and/or chemical intracellular signals. Recent work has increased our understanding of their gating mechanism, physiological functions and evolutionary origins. In particular, there has been major progress in research on microbial MS channels. Moreover, cloning and sequencing of MS channels from several species has provided insights into their evolution, their physiological functions in prokaryotes and eukaryotes, and their potential roles in the pathology of disease.
Barriers built on claudins
Authors: Turksen Kursad , Troy Tammy-Claire
Published: May 2004

The fundamental functions of epithelia and endothelia in multicellular organisms are to separate compositionally distinct compartments and regulate the exchange of small solutes and other substances between them. Tight junctions (TJs) between adjacent cells constitute the barrier to the passage of ions and molecules through the paracellular pathway and function as a `fence' within the plasma membrane to create and maintain apical and basolateral membrane domains. How TJs achieve this is only beginning to be understood. Recently identified components of TJs include the claudins, a family of four-transmembrane-span proteins that are prime candidates for molecules that function in TJ permeability. Their identification and characterization have provided new insight into the diversity of different TJs and heterogeneity of barrier functions in different epithelia and endothelia.
Environmental influence on testicular MAP kinase (ERK1) activity in the frogRana esculenta
Authors: Chieffi Paolo , Minucci Sergio
Published: May 2004

Recent studies suggest a role for ERK1 in the regulation of spermatogonial proliferation. In this report the frog Rana esculenta, a seasonal breeder, was used as a model to study the possible effect on ERK1 of photoperiod and temperature. Adult male R. esculenta were subjected to several combinations of light and temperature at different times of the year to elucidate the regulation of ERK1 testicular activity in the spermatogonial proliferation by these environmental factors.

Western blot analysis shows that under controlled experimental conditions an increase of temperature and photoperiod in November, characterized by a decrease in primary spermatogonial mitosis, induces ERK1 activity and spermatogonial proliferation, as confirmed using the proliferating cellular nuclear antigen (PCNA) as an early molecular marker. In contrast, a decrease in temperature and photoperiod in March, with an increase of primary spermatogonial mitosis, impairs ERK1 activity and spermatogonial proliferation.

In conclusion, our data clearly show for the first time in a non-mammalian vertebrate that the temperature and the photoperiod exert a role in the spermatogonial proliferation via ERK1 activity.
The stability of telomereless chromosome fragments in adult androgenetic rainbow trout
Authors: Ocalewicz K. , Babiak I. , Dobosz S. , Nowaczyk J. , Goryczko K.
Published: May 2004

The study provides new data on the stability of gamma radiation-induced chromosome fragments of a putative maternal nuclear genome in an androgenetic vertebrate, rainbow trout (Oncorhynchus mykiss Walbaum). The fragments were found in five of 16 examined individuals and they were mostly centromeric parts of metacentric or subtelocentric chromosomes. Chromosome fragments were identical in all cells of a given androgenetic individual,indicating that segregation of chromosome fragments is active from the early cell divisions. Most of the fragments were telomereless, i.e. they had no telomeric sequences on their ends. This shows that telomeres are not necessary for stability of chromosomal structures in a vertebrate genome. In one individual, the interstitial telomeric sites were found in chromosomes, which could be the effect of joining chromosome fragments.
Social responses without early experience: Australian brush-turkey chicks use specific visual cues to aggregate with conspecifics
Authors: Göth Ann , Evans Christopher S.
Published: May 2004

Almost all birds depend upon early experience with adults and siblings to learn recognition cues. Megapodes, such as the Australian brush-turkey(Alectura lathami), have evolved a very different life history. Eggs are incubated in mounds of decaying organic material. Chicks hatch asynchronously and receive no parental care, so imprinting cannot occur. Nevertheless, chicks subsequently form groups with similar-aged conspecifics. We explored the perceptual basis of this aggregation response, focussing on likely visual cues, such as pecking movements and body colour. Experiments were conducted under naturalistic conditions in a large aviary, using realistic robot models and colour filters. The robots successfully evoked a range of social responses resembling those of a live companion. Aggregation depended upon both behaviour and morphology. Simultaneous choice tests revealed that brush-turkey chicks preferred a pecking robot over either a static model or a scanning robot, suggesting that responsiveness depends upon particular movement patterns. In addition, chicks were sensitive to changes in appearance but only those that affected radiance at short wavelengths. The mechanism underlying social aggregation after hatching hence involves relatively specific cues. This perceptual bias seems to be largely experience independent and may exploit attributes to which potential predators are insensitive.
Negative effects of early developmental stress on yolk testosterone levels in a passerine bird
Authors: Gil Diego , Heim Claudia , Bulmer Elena , Rocha Milagros , Puerta Marisa , Naguib Marc
Published: May 2004

Female birds incorporate in the yolks of their eggs significant concentrations of a number of different androgens. Yolk androgen has been shown to positively affect several fitness components at the embryo, nestling and juvenile stages. Previous experiments have shown that females lay eggs with higher androgen concentrations when they are paired with highly ornamented males. This pattern suggests that yolk androgens are costly to females. In this study, we experimentally manipulated adult female condition in zebra finches Taeniopygia guttata by modifying the level of developmental stress they suffered as nestlings. This was achieved by cross-fostering nestlings to broods of varying brood size. Subsequently, we measured the yolk testosterone contents of the female offspring that resulted from the experimental manipulation. As predicted, females deposited decreasing concentrations of testosterone with increasing brood sizes experienced as nestlings: testosterone concentration (mean ± s.e.m.) of eggs laid by females from small broods, 20.66±2.08 pg mg–1; medium broods, 15.32±1.94 pg mg–1; and large broods, 14.51±1.66 pg mg–1. Additionally, testosterone concentration decreased with laying order, and varied with clutch size in a complex way. Differences in egg testosterone between females exposed to different brood sizes are in line with previous findings in showing that early developmental stress can affect adult reproductive performance, although our study did not detect an effect in other breeding parameters, such as latency to breed or clutch size. Furthermore, the results are consistent with the hypothesis that there is a cost associated with yolk testosterone. However, it is still unclear what the nature of this cost may be, and whether it is paid by females, offspring, or both.
Escape manoeuvres in the spiny dogfish (Squalus acanthias)
Authors: Domenici Paolo , Standen Emily M. , Levine Robert P.
Published: May 2004

The locomotor performance of dogfish during escape responses was observed by means of high-speed video. Dogfish show C-type escape responses that are comparable with those shown previously in teleosts. Dogfish show high variability of turning rates of the anterior part of the body (head to centre of mass), i.e. with peak values from 434 to 1023 deg. s-1. We suggest that this variability may be due to the presence of two types of escape manoeuvres, i.e. responses with high and low turning rates, as previously found in a teleost species. Fast responses (i.e. with high maximum turning rates, ranging between 766 and 1023 deg. s-1) showed significantly higher locomotor performance than slow responses (i.e. with low maximum turning rates, ranging between 434 and 593 deg. s-1) in terms of distance covered, speed and acceleration, although no differences were found in the turning radius of the centre of mass during the escape manoeuvres. The existence of two types of escape responses would have implications in terms of both neural control and muscular activation patterns. When compared with literature data for the locomotor performance of bony fishes, dogfish showed relatively low speed and acceleration, comparable turning rates and a turning radius that is in the low part of the range when compared with teleosts, indicating relatively high manoeuvrability. The locomotor performance observed in dogfish is consistent with their morphological characteristics: (1) low locomotor performance associated with low thrust developed by their relatively small posterior depth of section and(2) relatively high manoeuvrability associated with their high flexibility.
Changes in gene expression associated with acclimation to constant temperatures and fluctuating daily temperatures in an annual killifishAustrofundulus limnaeus
Authors: Podrabsky Jason E. , Somero George N.
Published: May 2004

Eurythermal ectotherms commonly thrive in environments that expose them to large variations in temperature on daily and seasonal bases. The roles played by alterations in gene expression in enabling eurytherms to adjust to these two temporally distinct patterns of thermal stress are poorly understood. We used cDNA microarray analysis to examine changes in gene expression in a eurythermal fish, Austrofundulus limnaeus, subjected to long-term acclimation to constant temperatures of 20, 26 and 37°C and to environmentally realistic daily fluctuations in temperature between 20°C and 37°C. Our data reveal major differences between the transcriptional responses in the liver made during acclimation to constant temperatures and in response to daily temperature fluctuations. Control of cell growth and proliferation appears to be an important part of the response to change in temperature, based on large-scale changes in mRNA transcript levels for several key regulators of these pathways. However, cell growth and proliferation appear to be regulated by different genes in constant versus fluctuating temperature regimes. The gene expression response of molecular chaperones is also different between constant and fluctuating temperatures. Small heat shock proteins appear to play an important role in response to fluctuating temperatures whereas larger molecular mass chaperones such as Hsp70 and Hsp90 respond more strongly to chronic high temperatures. A number of transcripts that encode for enzymes involved in the biosynthesis of nitrogen-containing organic osmolytes have gene expression patterns that indicate a possible role for these `chemical chaperones' during acclimation to chronic high temperatures and daily temperature cycling. Genes important for the maintenance of membrane integrity are highly responsive to temperature change. Changes in fatty acid saturation may be important in long-term acclimation and in response to fluctuating temperatures; however cholesterol metabolism may be most critical for short-term acclimation to fluctuating temperatures. The variable effect of temperature on the expression of genes with daily rhythms of expression indicates that there is a complex interaction between the temperature cycle and daily rhythmicity in gene expression. A number of new hypotheses concerning temperature acclimation in fish have been generated as a result of this study. The most notable of these hypotheses is the possibility that the high mobility group b1 (HMGB1) protein, which plays key roles in the assembly of transcription initiation and enhanceosome complexes, may act as a compensatory modulator of transcription in response to temperature, and thus as a global gene expression temperature sensor. This study illustrates the utility of cDNA microarray approaches in both hypothesis-driven and `discovery-based' investigations of environmental effects on organisms.
pH tolerances and regulatory abilities of freshwater and euryhaline Aedine mosquito larvae
Authors: Clark Thomas M. , Flis Benjamin J. , Remold Susanna K.
Published: May 2004

The pH regulatory abilities of two members of the mosquito tribe Aedini,known to have dramatically different saline tolerances, are investigated. The freshwater mosquito Aedes aegypti and the euryhaline Ochlerotatus taeniorhynchus tolerate very similar pH ranges. Both species complete larval development in waters ranging from pH 4 to pH 11, but naïve larvae always die in water of pH 3 or 12. Across the pH range 4–11, the hemolymph pH of O. taeniorhynchus is maintained constant while that of A. aegypti varies by 0.1 pH units. The salt composition of the water (3.5 g l–1 sea salt, 3.5 g l–1 NaCl,or nominally salt-free) has no effect on the range of pH tolerated by A. aegypti. In both species, the effects of pH on larval growth and development are minor in comparison with the influence of species and sex. Acclimation of A. aegypti to pH 4 or 11 increases survival times in pH 3 or 12, respectively, and allows a small percentage of larvae to pupate successfully at these extreme pH values. Such acclimation does not compromise survival at the other pH extreme.
Osmotic regulation in adultDrosophila melanogasterduring dehydration and rehydration
Authors: Albers Melissa A. , Bradley Timothy J.
Published: May 2004

We have examined the osmoregulatory capacities of laboratory populations of the insect Drosophila melanogaster by measuring hemolymph osmotic concentration during desiccation and upon recovery from a bout of desiccation. Recovery treatments entailed allowing the flies access to distilled water, a saline solution or a saline+sucrose solution after a desiccation bout shown to reduce hemolymph volume by ∼60%. Prior to desiccation, the hemolymph osmotic concentration was 353±11 mOsm. We found that Drosophila display strict osmotic regulation under prolonged conditions of dehydration. Osmotic regulation continued during recovery from desiccation, regardless of the fluid provided. This result is evidence that this insect does not require an external source of osmolytes or energy to regulate its hemolymph osmotic concentration or to restore hemolymph volume,which is reduced during desiccation. We also examined populations that have been selected for over 250 generations for enhanced desiccation resistance to identify physiological characters that have evolved in response to the selection regime. The selected lines displayed a reduced pre-desiccation hemolymph osmotic concentration (315±7 mOsm) and a marginally improved capacity for osmoregulation.