bluuebunny/crossref_metadata_2025 huggingface dataset:
Student Nurse Attitudes Towards Homeless Clients: a challenge for education and Practice
Authors: Zrinyi Miklos , Balogh Zoltan
Published: June 2004

The purpose of this research was to describe attitudes of nursing students (and paramedic officers) towards marginalized clients. Convenience quota sampling in a major health faculty was employed. Students participated on a voluntary basis. A 58-item Likert scale, developed by the authors, assessed the student nurses’ attitudes. In general, attitudes towards homeless clients were neutral; detailed analyses, however, revealed that student nurses would decline to care for homeless clients in various situations. Personal experience with homeless patients and positive attitudes of nurses significantly contributed to increased quality of care and equality of treatment for homeless clients. Certain student nurse behaviors warrant immediate attention to prevent marginalized patients from being exposed to unfair, inaccessible and biased nursing care. Based on our results, we recommend that further research attention be paid to the role of ethics education and faculty behaviors, as faculty members serve as role models for professionalization.
Nurses’ Attitudes to Euthanasia: a review of the literature
Authors: Verpoort Charlotte , Gastmans Chris , De Bal Nele , de Casterlé Bernadette Dierckx
Published: June 2004

This article provides an overview of the scarce international literature concerning nurses’ attitudes to euthanasia. Studies show large differences with respect to the percentage of nurses who are (not) in favour of euthanasia. Characteristics such as age, religion and nursing specialty have a significant influence on a nurse’s opinion. The arguments for euthanasia have to do with quality of life, respect for autonomy and dissatisfaction with the current situation. Arguments against euthanasia are the right to a good death, belief in the possibilities offered by palliative care, religious objections and the fear of abuse. Nurses mention the need for more palliative care training, their difficulties in taking a specific position, and their desire to express their ideas about euthanasia. There is a need to include nurses’ voices in the end-of-life discourse because they offer a contextual understanding of euthanasia and requests to die, which is borne out of real experience with people facing death.
The Influence of Nurses’ Attitudes, Subjective Norms and Perceived Behavioral Control on Maintaining Patients’ Privacy in a Hospital Setting
Authors: Tabak Nili , Ozon Meirave
Published: June 2004

The research reported in this article examined the influence of nurses’ attitudes, subjective norms and perceived behavioral control on maintaining patients’ privacy during hospitalization. The data were gathered from 109 nurses in six internal medicine wards at an Israeli hospital. The research was based on the theories of reasoned action and planned behavior. A positive and significant correlation was shown between nurses’ attitude to promoting and maintaining patient privacy and their planned behavior, while perceived behavioral control was the best variable for predicting the nurses’ behavior. Better educated nurses believed that they had fewer resources and anticipated more obstacles in acting to promote and maintain patient privacy. This research adds a new dimension to what is already known about nurses’ attitudes to maintaining patients’ privacy, nurses’ planned behavior and their actual behavior. The practical implications of the findings are the identification of factors that influence the attitudes and behavior of nursing staff, which, in turn, will enable allocation of resources for solving difficulties and removing obstacles. The results will allow the formulation of educational programs to guide staff and also the application of policies based on both patient and nursing staff needs.
Obtaining Informed Consent in an Egyptian Research Study
Authors: Rashad Amina M , Phipps Fiona MacVane , Haith-Cooper Melanie
Published: June 2004

This article explores the concept of internationally acceptable codes of ethics within the context of an Egyptian nurse’s PhD studies. Theoretical work, including gaining ethical approval for the project, took place in the UK, while the data collection phase of the study was done in Egypt. This highlighted areas where the Arab Muslim interpretation of some ethical principles, especially around the issue of gaining informed consent, differed from that currently accepted in British research ethics. The authors argue that it may not be possible, or even desirable, to standardize codes of ethics globally in areas such as academic research. Ethical principles develop from a unique mix of culture and religion. It may be more important to develop cultural competence that includes the ability to understand and respect the way in which ethical principles are interpreted by various societies.
Acknowledging Dependence: a MacIntyrean perspective on relationships involving Alzheimer’s Disease
Authors: Butts Janie B , Rich Karen L
Published: June 2004

As people living with Alzheimer ’s disease experience their lifetime of memories slowly slipping away, they become dependent on society’s independent practical reasoners - family, health care professionals and society. Many people grow accustomed to the cognitive decline and begin to view the person with dementia as less than a person. In Dependent rational animals, Alasdair MacIntyre emphasized a moral framework that encompasses two sets of virtues needed for human beings to flourish in society and to achieve genuine common goods - the virtues of independent practical reasoners and the virtues of acknowledged dependence. Virtues of acknowledged dependence are discussed ethically in terms of benevolence towards those who are disabled or dependent upon people who are strong and independent. The authors propose that using MacIntyre’s perspective of the two sets of virtues is valuable in the care of persons with Alzheimer ’s disease. According to MacIntyre, independent reasoners who understand and practice these two sets of virtues will help those people in communities who are dependent and vulnerable, and, subsequently, human flourishing can occur.
Skin and skin substitutes in burn management
Authors: Chester DL , Papini RPG
Published: June 2004

Early burn excision has reduced the mortality from major burns. This practice presents the problem of wound coverage after excision, since the availability of autologous donor sites is limited in very large burns. This article reviews the methods available for covering burn wounds. Methods of expanding autologous skin are discussed as well as techniques using allogeneic tissue and xenograft. Newer synthetic skin substitutes have become an important advance and are also described. Cultured skin replacements are also discussed along with their shortfalls. The treatment of a patient with major burns may require the use of many different skin substitutes, as none is entirely satisfactory on its own.
Head trauma
Authors: Benham J , Chavda SV
Published: June 2004

The role of radiological imaging modalities in the investigation of head trauma is reviewed with reference to the mechanisms of head injury, as well as the recent guidelines for investigation produced by the National Institute for Clinical Excellence (NICE), and the Royal College of Radiologists. Lesions resulting from head trauma and the associated radiological ndings are described.
Paediatric prehospital trauma
Authors: Jewkes Fiona
Published: June 2004

The commonest cause of death in children is trauma, yet few studies have been undertaken to study their needs in the prehospital setting. This article examines the problems associated with seriously traumatized children in the prehospital setting and reviews their management with reference to the specific differences between adults and children. A systematic review of the primary survey is made. Other important aspects of their care including equipment, analgesia, child abuse and accident prevention are also discussed. The need for further research in this field to allow children to enjoy the standard of care afforded adults is emphasized.
Mechanotransduction in Cardiac Myocytes
Authors: LAMMERDING JAN , KAMM ROGER D. , LEE RICHARD T.
Published: June 2004

Abstract: Cardiac myocytes react to diverse mechanical demands with a multitude of transient and long‐term responses to normalize the cellular mechanical environment. Several stretch‐activated signaling pathways have been identified, most prominently guanine nucleotide binding proteins (G‐proteins), mitogen‐activated protein kinases (MAPK), Janus‐associated kinase/signal transducers and activators of transcription (JAK/STAT), protein kinase C (PKC), calcineurin, intracellular calcium regulation, and several autocrine and paracrine factors. Multiple levels of crosstalk exist between pathways. The cellular response to changes in the mechanical environment can lead to cardiac myocyte hypertrophy, cellular growth that can be accompanied by pathological myocyte dysfunction, and tissue fibrosis. Several candidates for the primary mechanosensor in cardiac myocytes have been identified, ranging from stretch‐activated ion channels in the membrane to yet‐unknown mechanosensitive mechanisms in the nucleus. New and refined experimental techniques will exploit advances in molecular biology and biological imaging to study mechanotransduction in isolated cells and genetically engineered mice to explore the function of individual proteins.
Congestive Heart Failure after Myocardial Infarction in the Rat: Cardiac Force and Spontaneous Sarcomere Activity
Authors: DAVIDOFF A W , BOYDEN P A , SCHWARTZ K , MICHEL J B , ZHANG Y M , OBAYASHI M , CRABBE D , TER KEURS H E D J
Published: June 2004

Abstract: The causes of reduced cardiac force development in congestive heart failure (CHF) are still uncertain. We explored the subcellular mechanisms leading to decreased force development in trabeculae from rats with a myocardial infarction. We defined CHF according to clinical and pathological criteria and compared properties of trabeculae from animals with CHF (cMI) to those of animals with a myocardial scar but without evidence of CHF (uMI), and sham‐operated animals. The new findings of this study on properties of cMI trabeculae are that (1) maximal twitch force following post‐extrasystolic potentiation is unchanged; (2) the sensitivity of cMI trabeculae to [Ca2+]o is increased; (3) spontaneous diastolic sarcomere length (SL) fluctuations (SA) are increased in cMI at all levels of SR Ca2+ loading; and (4) SA is accompanied by a proportional reduction of Fmax. The results suggest that the probability of spontaneous diastolic opening of SR Ca2+ channels is increased in CHF. These data provide the basis for a novel mechanism underlying systolic and diastolic dysfunction as well as arrhythmias in hearts in CHF. If SA proves to be a component of myocardial dysfunction in human CHF, our thinking about therapy of the patient with CHF may be profoundly changed.
Cardiac Fiber Orientation and the Left‐Right Asymmetry Determining Mechanism
Authors: DELHAAS TAMMO , DECALUWE WIM , RUBBENS MIRJAM , KERCKHOFFS ROY , ARTS THEO
Published: June 2004

Abstract: The invariant nature of body situs within and across vertebrate species implies that a highly conserved pathway controls the specification of the left‐right (L/R) axis. Situs‐specific morphogenesis begins at the end of this pathway and leads to normal organ arrangement, also known as situs solitus. Occasionally, individuals have a complete, mirror image reversal of this asymmetry, called situs inversus totalis (SIT). In these individuals, gross anatomy is mirror imaged. However, the helical myofiber pattern within the left ventricle (LV) wall is only partially mirror imaged: apical and superficial basal fiber orientation are as in normal persons, whereas the deeper basal layers have an inverted fiber orientation. Because of this bivalent fiber orientation pattern, LV deformation in humans with SIT is mirror imaged only near the base, but near the apex it is as in normal subjects. Apparently, the embryonic L/R controlling genetic pathway does determine situs‐specific gross anatomy morphogenesis, but it is not the only factor regulating fiber architecture within the LV wall.
Determining the Relationship Between Toxicity and Quality of Life in an Ovarian Cancer Chemotherapy Clinical Trial
Authors: Butler Lorna , Bacon Monica , Carey Mark , Zee Benny , Tu Dongsheng , Bezjak Andrea
Published: June 2004

Purpose

This analysis of data from a randomized trial of chemotherapy in epithelial ovarian cancer sought to determine whether a relationship exists between the presence and severity of the most commonly observed toxic effects and the corresponding quality of life (QOL) items.

Patients and Methods

One hundred fifty-two eligible patients accrued from Canada by the National Cancer Institute of Canada Clinical Trials Group on a randomized trial of paclitaxel and cisplatin versus cyclophosphamide/cisplatin were included in the analysis. Toxicity to the chemotherapeutic treatments was subjectively evaluated using a trial-specific checklist for ovarian cancer and the European Organization for Research and Treatment of Cancer QLQ C30+3 questionnaire. Assessments were conducted at baseline, before each cycle of treatment (3 weeks), and at each 3-month follow-up during the next 2 years (or until progression).

Results

The most frequently observed symptoms experienced during or shortly following chemotherapy were neurosensory loss, lethargy, nausea, vomiting, and alopecia. Regression analyses revealed that change scores of QOL items related to motor weakness and gastrointestinal pain were common predictors for the change global QOL score during protocol treatment; and change scores of QOL items related to lethargy or fatigue and change toxicity grade of mood predicted the change global QOL score after patients were off treatment.

Conclusion

The use of the European Organization for Research and Treatment of Cancer QLQ C30+3 and trial-specific checklist was able to assess the effect of expected toxicities on patient's QOL during and following treatment, and so may be useful in addressing the concerns regarding methodological issues that have limited the acquisition of prospective, longitudinal treatment-related toxicity data.
The Risk of Cancer in Users of Statins
Authors: Graaf Matthijs R. , Beiderbeck Annette B. , Egberts Antoine C.G. , Richel Dick J. , Guchelaar Henk-Jan
Published: June 2004

Purpose

Several preclinical studies suggested a role for 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors (statins) in the treatment of cancer. The objective of this study was to compare the risk of incident cancer between users of statins and users of other cardiovascular medication.

Methods

Data were used from the PHARMO database, containing drug dispensing records from community pharmacies and linked hospital discharge records for residents of eight Dutch cities. The study base included all patients with one or more prescriptions for cardiovascular drugs in the period between January 1, 1985 and December 31, 1998. Cases were identified as patients in the study base with a diagnosis of incident cancer and matched with four to six controls on sex, year of birth, geographic region, duration of follow-up, and index date. The analysis was adjusted for diabetes mellitus; prior hospitalizations; comorbidity; and use of diuretics, angiotensin-converting enzyme inhibitors, calcium-channel blockers, nonsteroidal anti-inflammatory drugs, sex hormones, and other lipid-lowering drug therapies.

Results

In the study base, 3,129 patients were identified and matched to 16,976 controls. Statin use was associated with a risk reduction of cancer of 20% (adjusted odds ratio [OR], 0.80; 95% CI, 0.66 to 0.96). Our data suggest that statins are protective when used longer than 4 years (adjusted OR, 0.64; 95% CI, 0.44 to 0.93) or when more than 1,350 defined daily doses are taken (adjusted OR, 0.60; 95% CI, 0.40 to 0.91).

Conclusion

This observational study suggests that statins may have a protective effect against cancer.
Contralateral Breast Cancer in BRCA1 and BRCA2 Mutation Carriers
Authors: Metcalfe Kelly , Lynch Henry T. , Ghadirian Parviz , Tung Nadine , Olivotto Ivo , Warner Ellen , Olopade Olufunmilayo I. , Eisen Andrea , Weber Barbara , McLennan Jane , Sun Ping , Foulkes William D. , Narod Steven A.
Published: June 2004

Purpose

To estimate the risk of contralateral breast cancer in BRCA1 and BRCA2 carriers after diagnosis and to determine which factors are predictive of the risk of a second primary breast cancer.

Patients and Methods

Patients included 491 women with stage I or stage II breast cancer, for whom a BRCA1 or BRCA2 mutation had been identified in the family. Patients were followed from the initial diagnosis of cancer until contralateral mastectomy, contralateral breast cancer, death, or last follow-up.

Results

The actuarial risk of contralateral breast cancer was 29.5% at 10 years. Factors that were predictive of a reduced risk were the presence of a BRCA2 mutation (v BRCA1 mutation; hazard ratio [HR], 0.73; 95% CI, 0.47 to 1.15); age 50 years or older at first diagnosis (v ≤ 49 years; HR, 0.63; 95% CI, 0.36 to 1.10); use of tamoxifen (HR, 0.59; 95% CI, 0.35 to 1.01); and history of oophorectomy (HR, 0.44; 95% CI, 0.21 to 0.91). The effect of oophorectomy was particularly strong in women first diagnosed prior to age 49 years (HR, 0.24; 95% CI, 0.07 to 0.77). For women who did not have an oophorectomy or take tamoxifen, the 10-year risk of contralateral cancer was 43.4% for BRCA1 carriers and 34.6% for BRCA2 carriers.

Conclusion

The risk of contralateral breast cancer in women with a BRCA mutation is approximately 40% at 10 years, and is reduced in women who take tamoxifen or who undergo an oophorectomy.
Cost Minimization Study of Image-Guided Core Biopsy Versus Surgical Excisional Biopsy for Women With Abnormal Mammograms
Authors: Golub Robert M. , Bennett Charles L. , Stinson Tammy , Venta Luz , Morrow Monica
Published: June 2004

Purpose

To describe the clinical and economic consequences of image-guided core biopsy versus surgical excisional biopsy of mammographically identified breast lesions.

Patients and Methods

Clinical and economic data were collected for 1,121 patients undergoing core biopsies and 501 patients undergoing surgical biopsies between 1996 and 1998. Lesions were classified according to mammographic degree of suspicion and type of radiographic abnormality. Costs were measured from the societal perspective. A decision analytic model was constructed, with probabilistic sensitivity analysis.

Results

Lesions diagnosed via core versus surgical biopsy were less likely to be masses (39% v 55%), less likely to be classified as high cancer suspicion (17% v 26%), and less likely to be treated with a single procedure (74% v 81%; P < .001 for each). Cancers diagnosed by a surgical biopsy were less likely to have had a single operative procedure (33% v 84%) and were associated with higher total costs whether mastectomy ($2,775 v $1,849) or lumpectomy ($2,112 v $1,365) was used. Sensitivity analysis showed core biopsy optimal in 95.4% of trials. Core biopsy was favored for low-suspicion lesions, calcifications, and masses, and overall for patients who underwent lumpectomy alone.

Conclusion

Image-guided core biopsy can be cost-saving compared with surgical biopsy, particularly when the mammographic abnormality is classified as low suspicion or consists of calcifications or masses. Moving to a policy in which core biopsy is the preferred approach in these settings has the potential to result in significant cost savings.
Herbal Remedies in the United States: Potential Adverse Interactions With Anticancer Agents
Authors: Sparreboom Alex , Cox Michael C. , Acharya Milin R. , Figg William D.
Published: June 2004

Purpose

Interest in the use of herbal products has grown dramatically in the Western world. Recent estimates suggest an overall prevalence for herbal preparation use of 13% to 63% among cancer patients. With the narrow therapeutic range associated with most anticancer drugs, there is an increasing need for understanding possible adverse drug interactions in medical oncology.

Methods

In this article, a literature overview is provided of known or suspected interactions of the 15 best-selling herbs in the United States with conventional allopathic therapies for cancer.

Results

Herbs with the potential to significantly modulate the activity of drug-metabolizing enzymes (notably cytochrome P450 isozymes) and/or the drug transporter P-glycoprotein include garlic (Allium sativum), ginkgo (Ginkgo biloba), echinacea (Echinacea purpurea), ginseng (Panax ginseng), St John's wort (Hypericum perforatum), and kava (Piper methysticum). All of these products participate in potential pharmacokinetic interactions with anticancer drugs.

Conclusion

It is suggested that health care professionals and consumers should be aware of the potential for adverse interactions with these herbs, question their patients on their use of them, especially among patients whose disease is not responding to treatments as expected, and urge patients to avoid herbs that could confound their cancer care.
Phase I Trial and Pharmacokinetics of Gemcitabine in Children With Advanced Solid Tumors
Authors: Reid Joel M. , Qu Wenchun , Safgren Stephanie L. , Ames Matthew M. , Krailo Mark D. , Seibel Nita L. , Kuttesch John , Holcenberg John
Published: June 2004

Purpose

To determine the maximum tolerated dose, toxicity, and pharmacokinetics of gemcitabine in children with refractory solid tumors.

Patients and Methods

Gemcitabine was given as a 30-minute infusion for 2 or 3 consecutive weeks every 4 weeks, to 42 patients aged 1 to 21 years. Doses of 1,000, 1,200 and 1,500 mg/m2 were administered for 3 weeks. Subsequently, gemcitabine was given for only 2 consecutive weeks at 1,500, 1,800, and 2,100 mg/m2. Plasma concentrations of gemcitabine and its metabolite, 2′2′-difluorodeoxyuridine, were measured in 28 patients.

Results

Forty patients who received 132 courses of gemcitabine were assessable for toxicity. The maximum tolerated dose of gemcitabine given weekly for 3 weeks was 1,200 mg/m2. Dose-limiting toxicity was not seen in one-third of children treated at any doses given for 2 weeks. The major toxicity was myelosuppression in three of five patients at 1,500 mg/m2 for 3 weeks, and one of seven patients at 1,800 mg/m2 for 2 weeks. Other serious adverse events were somnolence, fever and hypotension, and rash in three patients. Gemcitabine plasma concentration–time data were fit to a one- (n = 5) or two-compartment (n = 23) open model. Mean gemcitabine clearance and half-life values were 2,140 mL/min/m2 and 13.7 minutes, respectively. One patient with pancreatic cancer had a partial response. Seven patients had stable disease for 2 to 17 months.

Conclusion

Gemcitabine given by 30-minute infusion for 2 or 3 consecutive weeks every 4 weeks was tolerated well by children at doses of 2,100 mg/m2 and 1,200 mg/m2, respectively.
Modeling the Development of Infant Categorization
Authors: Cohen Leslie B.
Published: June 2004

Research on infant categorization has made remarkable progress since the first studies were reported in the late 1970s (e.g., Cohen & Caputo, 1978; Cohen & Strauss, 1977; Strauss, 1979). This progress is evident in a recent volume on early categorization and concept acquisition (Rakison & Oakes, 2003), the first half of which is devoted entirely to theory and research on infant categorization. Even in the early days of such research an important distinction was made between demonstration‐oriented studies and process‐oriented studies (Cohen & Younger, 1983; Younger & Cohen, 1985). Demonstration studies simply presented infants with established category items (by adult standards) such as pictures of stuffed animals, faces, dogs, cats, animals, or vehicles and examined whether infants would generalize their responding to novel members of the same category. Process studies, on the other hand, presented infants with novel categories and manipulated feature values of category items to examine the mechanisms underlying infant category acquisition.
From Parts to Wholes: Mechanisms of Development in Infant Visual Object Processing
Authors: Westermann Gert , Mareschal Denis
Published: June 2004

Visual object processing in infancy is often described as proceeding from an early stage in which object features are processed independently to a later stage in which relations between features are taken into account (e.g., Cohen, 1998). Here we present the Representational Acuity Hypothesis, which argues that this behavioral shift can be explained by a developmental decrease in the size of neural receptive fields in the cortical areas responsible for object representation, together with a tuning to specific object features. We evaluate this hypothesis with a connectionist model of infant perceptual categorization. The model shows a behavioral shift in featural to relational processing consistent with similar results observed in the infant categorization experiments of Younger (1985) and Younger and Cohen (1986).
Modeling Age Differences in Infant Category Learning
Authors: Shultz Thomas R. , Cohen Leslie B.
Published: June 2004

We used an encoder version of cascade correlation to simulate Younger and Cohen's (1983, 1986) finding that 10‐month‐olds recover attention on the basis of correlations among stimulus features, but 4‐ and 7‐month‐olds recover attention on the basis of stimulus features. We captured these effects by varying the score threshold parameter in cascade correlation, which controls how deeply training patterns are learned. When networks learned deeply, they showed more error to uncorrelated than to correlated test patterns, indicating that they abstracted correlations during familiarization. When prevented from learning deeply, networks decreased error during familiarization and showed as much error to correlated as to uncorrelated tests but less than to test items with novel features, indicating that they learned features but not correlations among features. Our explanation is that older infants learn more from the same exposure than do younger infants. Unlike previous explanations that postulate unspecified qualitative shifts in processing with age, our explanation focuses on quantitatively deeper learning with increasing age. Finally, we provide some new empirical evidence to support this explanation.
Common Mechanisms in Infant and Adult Category Learning
Authors: Gureckis Todd M. , Love Bradley C.
Published: June 2004

Computational models of infant categorization often fail to elaborate the transitional mechanisms that allow infants to achieve adult performance. In this article, we apply a successful connectionist model of adult category learning to developmental data. The Supervised and Unsupervised Stratified Adaptive Incremental Network (SUSTAIN) model is able to account for the emergence of infants' sensitivity to correlated attributes (e.g., has wings and can fly). SUSTAIN offers 2 complimentary explanations of the developmental trend. One explanation centers on memory storage limitations, whereas the other focuses on limitations in perceptual systems. Both explanations parallel published findings concerning the cognitive and sensory limitations of infants. SUSTAIN's simulations suggest that conceptual development follows a continuous and smooth trajectory despite qualitative changes in behavior and that the mechanisms that underlie infant and adult categorization might not differ significantly.
How Do Simple Connectionist Networks Achieve a Shift From “Featural” to “Correlational” Processing in Categorization?
Authors: Thomas Michael S. C.
Published: June 2004

Three developmental connectionist models simulate a purported shift from “featural” to “correlational” processing in infant categorization (models: Gureckis & Love, 2004/this issue; Shultz & Cohen, 2004/this issue; Westermann & Mareschal, 2004/this issue; empirical data: Cohen & Arthur, 2003; Younger, 1985; Younger & Cohen, 1986). In this article, the way in which the models are able to simulate the behavioral data is revealed, and their respective theoretical commitments are evaluated. Together the models argue that the shift from featural to correlational processing in infant categorization might be illusory, as these models are able to replicate the key behavioral features while processing correlations right from the start. As such, they claim the behavioral description of a shift is not reflected at the level of mechanism.
An Emerging Consensus: Younger and Cohen Revisited
Authors: Younger Barbara A. , Hollich George , Furrer Stephanie D.
Published: June 2004

From Aesop to Sun Tzu, the importance of working together has long been acknowledged. Yet as long as cooperation has existed, so have the difficulties associated with it. Pooling two fields might mean twice the power, but this union also brings twice the jargon, twice the competing theories, and twice the head butting. Nonetheless, in this collection, researchers have made a heroic effort to set aside their theoretical differences to produce three computational models for the influential set of empirical data showing that young infants have difficulty detecting correlations among features (Younger & Cohen, 1983, 1986). Specifically, Gureckis and Love (2004/this issue) fit a well‐developed adult‐learning model to the infant work (down to the exact order and number of test trials) in support of a common mechanism underlying categorization. Shultz and Cohen (2004/this issue) vary depth of processing in a cascade correlation network to show how older infants learn more than younger infants from the same amount of exposure. And Westermann and Mareschal (2004/this issue) introduce a model for their representational acuity hypothesis, which explains qualitative shifts as a decrease in the size of neural receptive fields. This commentary takes stock of this attempt at unifying computational modeling and developmental data by identifying common themes, clarifying points of disagreement, and providing a synthesis for this work.
Demands on Finite Cognitive Capacity Cause Infants' Perseverative Errors
Authors: Berger Sarah E.
Published: June 2004

This research unites traditionally disparate developmental domains—cognition and locomotion—to examine the classic cognitive issue of the development of inhibition in infancy. In 2 locomotor A‐not‐B tasks, 13‐month‐old walking infants inhibited a prepotent response under low task demands (walking on flat ground), but perseverated under increased task demands (descending a staircase). Despite elimination of factors previously associated with infant perseveration, infants still perseverated in the difficult stairs condition. Increasing cognitive load by manipulating task difficulty affected infants' ability to inhibit repeated responses that were no longer appropriate. Evidence supports a cognitive capacity account of infant perseveration, in which infants' performance depends on allocation of cognitive and attentional resources.
Attentional Engagement in Infancy: The Interactive Influence of Attentional Inertia and Attentional State
Authors: Oakes Lisa M. , Ross‐Sheehy Shannon , Kannass Kathleen N.
Published: June 2004

We evaluated the interactive influences of attentional state and attentional inertia on infants' level of attentional engagement. We assessed infants' distraction latencies longitudinally at 6.5 and 9 months as they explored toys, and we coded both their attentional state (focused vs. casual) and how long they had been looking at the toy at each distractor onset. Consistent with previous results, both attentional state and attentional inertia contributed to differences in distraction latency. Importantly, the level of attentional engagement was interactively determined by attentional state and attentional inertia. Infants were most resistant to distraction when they were judged to be in a state of focused attention following relatively long looks to the toy, and they were equivalently less resistant to distraction under all other conditions. These results are consistent with a general conceptualization of attentional engagement resulting from the interaction of multiple processes.
Bmp2 antagonizes sonic hedgehog-mediated proliferation of cerebellar granule neurones through Smad5 signalling
Authors: Rios Iria , Alvarez-Rodríguez Rubén , Martí Elisa , Pons Sebastián
Published: June 2004

During development of the cerebellum, sonic hedgehog (Shh) is directly responsible for the proliferation of granule cell precursors in the external germinal layer. We have looked for signals able to regulate a switch from the Shh-mediated proliferative response to one that directs differentiation of granule neurones. Bone morphogenetic proteins (BMPs) are expressed in distinct neuronal populations within the developing cerebellar cortex. Bmp2 and Bmp4 are expressed in the proliferating precursors and subsequently in differentiated granule neurones of the internal granular layer, whereas Bmp7 is expressed by Purkinje neurones. In primary cultures, Bmp2 and Bmp4, but not Bmp7, are able to prevent Shh-induced proliferation, thereby allowing granule neuron differentiation. Furthermore, Bmp2 treatment downregulates components of the Shh pathway in proliferating granule cell precursors. Smad proteins,the only known BMP receptor substrates capable of transducing the signal, are also differentially expressed in the developing cerebellum: Smad1 in the external germinal layer and Smad5 in newly differentiated granule neurones. Among them, only Smad5 is phosphorylated in vivo and in primary cultures treated with Bmp2, and overexpression of Smad5 is sufficient to induce granule cell differentiation in the presence of Shh. We propose a model in which Bmp2-mediated Smad5 signalling suppresses the proliferative response to Shh by downregulation of the pathway, and allows granule cell precursor to enter their differentiation programme.
Parallels between tissue repair and embryo morphogenesis
Authors: Martin Paul , Parkhurst Susan M.
Published: June 2004

Wound healing involves a coordinated series of tissue movements that bears a striking resemblance to various embryonic morphogenetic episodes. There are several ways in which repair recapitulates morphogenesis. We describe how almost identical cytoskeletal machinery is used to repair an embryonic epithelial wound as is involved during the morphogenetic episodes of dorsal closure in Drosophila and eyelid fusion in the mouse foetus. For both naturally occurring and wound-activated tissue movements, JNK signalling appears to be crucial, as does the tight regulation of associated cell divisions and adhesions. In the embryo, both morphogenesis and repair are achieved with a perfect end result, whereas repair of adult tissues leads to scarring. We discuss whether this may be due to the adult inflammatory response, which is absent in the embryo.
Quantification of the cytoplasmic spaces of living cells with EGFP reveals arrestin-EGFP to be in disequilibrium in dark adapted rod photoreceptors
Authors: Peet Jon A. , Bragin Alvina , Calvert Peter D. , Nikonov Sergei S. , Mani Shoba , Zhao Xinyu , Besharse Joseph C. , Pierce Eric A. , Knox Barry E. , Pugh Edward N.
Published: June 2004

The hypothesis is tested that enhanced green fluorescent protein (EGFP) can be used to quantify the aqueous spaces of living cells, using as a model transgenic Xenopus rods. Consistent with the hypothesis, regions of rods having structures that exclude EGFP, such as the mitochondrial-rich ellipsoid and the outer segments, have highly reduced EGFP fluorescence. Over a 300-fold range of expression the average EGFP concentration in the outer segment was approximately half that in the most intensely fluorescent regions of the inner segment, in quantitative agreement with prior X-ray diffraction estimates of outer segment cytoplasmic volume. In contrast, the fluorescence of soluble arrestin-EGFP fusion protein in the dark adapted rod outer segment was approximately threefold lower than predicted by the EGFP distribution, establishing that the fusion protein is not equilibrated with the cytoplasm. Arrestin-EGFP mass was conserved during a large-scale, light-driven redistribution in which ∼40% of the protein in the inner segment moved to the outer segment in less than 30 minutes.
Visualizing Ras signalling in real-time
Authors: Walker Simon A. , Lockyer Peter J.
Published: June 2004

Ras GTPases are universal molecular switches that act as kinetic timers of signal transduction events. They are post-translationally modified by the addition of lipid groups to their hypervariable carboxyl termini, which plug the proteins to membranes and influence their dynamic sorting and trafficking. For the past twenty years, the plasma membrane has been considered to be the predominant platform from which Ras operates. Recent work using live-cell imaging and novel probes to visualize where and when Ras is active has supported this long-held belief. However, an equally fascinating aspect of these imaging studies has been the discovery of dynamic Ras activity, as well as distinct signal output, from intracellular organelles. Activation of Ras on the Golgi exhibits kinetics different from Ras activation on the plasma membrane, and compartmentalized Ras signalling seems particularly prominent in lymphocytes. However, data on the spatial and temporal regulation of Ras activity has frequently differed depending on the nature of the probe, the cell type and the stimulus. Nevertheless, because Ras traffics through endomembranes en route to the plasma membrane, it seems likely that Ras can signal from such compartments. The burning question in this field concerns the significance of this observation for endogenous Ras signalling output.
Dynamics and inheritance of the endoplasmic reticulum
Authors: Du Yunrui , Ferro-Novick Susan , Novick Peter
Published: June 2004

The endoplasmic reticulum (ER) consists of a polygonal array of interconnected tubules and sheets that spreads throughout the eukaryotic cell and is contiguous with the nuclear envelope. This elaborate structure is created and maintained by a constant remodeling process that involves the formation of new tubules, their cytoskeletal transport and homotypic fusion. Since the ER is a large, single-copy organelle, it must be actively segregated into daughter cells during cell division. Recent analysis in budding yeast indicates that ER inheritance involves the polarized transport of cytoplasmic ER tubules into newly formed buds along actin cables by a type V myosin. The tubules then become anchored to a site at the bud tip and this requires the Sec3p subunit of the exocyst complex. The ER is then propagated along the cortex of the bud to yield a cortical ER structure similar to that of the mother cell. In animal cells, the ER moves predominantly along microtubules, whereas actin fibers serve a complementary role. It is not yet clear to what extent the other components controlling ER distribution in yeast might be conserved in animal cells.
The evolution of recovery from desiccation stress in laboratory-selected populations ofDrosophila melanogaster
Authors: Folk Donna G. , Bradley Timothy J.
Published: June 2004

We examined the capacity for physiological recovery from the effects of desiccation in five replicate populations of Drosophila melanogasterthat have been selected for enhanced desiccation resistance (D populations)and in five replicate control populations (C populations). The capacity to recover was signified by the ability to restore three somatic components,namely whole-body water, dry mass and sodium content, all of which are reduced during desiccation. Throughout a period of recovery following a bout of desiccation, the flies were offered one of three fluids: distilled water,saline solution, or saline+sucrose solution. Our findings indicate that, when allowed to recover on saline+sucrose solution, D populations have the capacity to restore water at a greater rate than C populations and are able to fully restore dry mass and sodium content to the levels observed in non-desiccated,hydrated D flies. When provided with this same solution during recovery, C flies are unable to restore dry mass and are faced with an elevated sodium load. Desiccation resistance of the flies subsequent to recovery was also examined. We provide evidence that the greatest desiccation resistance in the D populations is associated with the restoration of all three somatic components, suggesting that not only water content, but also dry mass and sodium, may contribute to the enhanced desiccation resistance that has evolved in these populations.
Cadmium effects on mitochondrial function are enhanced by elevated temperatures in a marine poikilotherm,Crassostrea virginicaGmelin(Bivalvia: Ostreidae)
Authors: Sokolova I. M.
Published: June 2004

Marine intertidal mollusks, such as oysters, are exposed to multiple stressors in estuaries, including varying environmental temperature and levels of trace metals, which may interactively affect their physiology. In order to understand the combined effects of cadmium and elevated temperature on mitochondrial bioenergetics of marine mollusks, respiration rates and mitochondrial volume changes were studied in response to different cadmium levels (0–1000 μmol l–1) and temperatures (15, 25 and 35°C) in isolated mitochondria from the eastern oyster Crassostrea virginica acclimated at 15°C. It was found that both cadmium and temperature significantly affect mitochondrial function in oysters. Elevated temperature had a rate-enhancing effect on state 3 (ADP-stimulated) and states 4 and 4+ (representative of proton leak) respiration, and the rate of temperature-dependent increase was higher for states 4 and 4+ than for state 3 respiration. Exposure of oyster mitochondria to 35°C resulted in a decreased respiratory control and phosphorylation efficiency (P/O ratio)compared to that of the acclimation temperature (15°C), while an intermediate temperature (25°C) had no effect. Cadmium exposure did not lead to a significant volume change in oyster mitochondria in vitro. Low levels of cadmium (1–5 μmol l–1) stimulated the rate of proton leak in oyster mitochondria, while not affecting ADP-stimulated state 3 respiration. In contrast, higher cadmium levels (10–50 μmol l–1) had little or no effect on proton leak, but significantly inhibited state 3 respiration by 40–80% of the control rates. Elevated temperature increased sensitivity of oyster mitochondria to cadmium leading to an early inhibition of ADP-stimulated respiration and an onset of complete mitochondrial uncoupling at progressively lower cadmium concentrations with increasing temperature. Enhancement of cadmium effects by elevated temperatures suggests that oyster populations subjected to elevated temperatures due to seasonal warming or global climate change may become more susceptible to trace metal pollution, and vice versa.
Ontogenetic patterns of limb loading,in vivobone strains and growth in the goat radius
Authors: Main Russell P. , Biewener Andrew A.
Published: June 2004

As tetrapods increase in size and weight through ontogeny, the limb skeleton must grow to accommodate the increases in body weight and the resulting locomotor forces placed upon the limbs. No study to date, however,has examined how morphological changes in the limb skeleton during growth reflect ontogenetic patterns of limb loading and the resulting stresses and strains produced in the limbs. The goal of this study was to relate forelimb loads to in vivo bone strains in the radius of the domestic goat(Capra hircus) across a range of gaits and speeds through ontogeny while observing how the growth patterns of the bone relate to the mechanics of the limb. In vivo bone strains in the radius were recorded from two groups of juvenile goats (4 kg, 6 weeks and 9 kg, 15 weeks) and compared with previously reported strain data for the radius of adult goats. Ontogenetic strain patterns were examined in relation to peak forelimb ground reaction forces, ontogenetic scaling patterns of cross-sectional geometry and bone curvature, and percentage mineral ash content. Peak principal longitudinal tensile strains on the cranial surface and compressive strains on the caudal surface of the radius increased during ontogeny but maintained a uniform distribution, resulting in the radius being loaded primarily in bending through ontogeny. The increase in strain occurred despite uniform loading(relative to body weight) of the forelimb through ontogeny. Instead, the increase in bone strain resulted from strong negative growth allometry of the cross-sectional area (∝M0.53) and medio-lateral and cranio-caudal second moments of area(IML∝M1.03, ICC∝M0.84) of the radius and only a small increase (+2.8%) in mineral ash content. Even though bone strains increased with growth and age, strains in the younger goats were small enough to suggest that they maintain safety factors at least comparable with adults when moving at similar absolute speeds. Increased variability of loading in juvenile animals may also favor the more robust dimensions of the radius, and possibly other limb bones, early in growth.
Innate immunity in the malaria vectorAnopheles gambiae:comparative and functional genomics
Authors: Osta Mike A. , Christophides George K. , Vlachou Dina , Kafatos Fotis C.
Published: June 2004

The resurgence of malaria is at least partly attributed to the absence of an effective vaccine, parasite resistance to antimalarial drugs and resistance to insecticides of the anopheline mosquito vectors. Novel strategies are needed to combat the disease on three fronts: protection (vaccines),prophylaxis/treatment (antimalarial drugs) and transmission blocking. The latter entails either killing the mosquitoes (insecticides), preventing mosquito biting (bednets and repellents), blocking parasite development in the vector (transmission blocking vaccines), genetic manipulation or chemical incapacitation of the vector. During the past decade, mosquito research has been energized by several breakthroughs, including the successful transformation of anopheline vectors, analysis of gene function by RNAi,genome-wide expression profiling using DNA microarrays and, most importantly,sequencing of the Anopheles gambiae genome. These breakthroughs helped unravel some of the mechanisms underlying the dynamic interactions between the parasite and the vector and shed light on the mosquito innate immune system as a set of potential targets to block parasite development. In this context, putative pattern recognition receptors of the mosquito that act as positive and negative regulators of parasite development have been identified recently. Characterizing these molecules and others of similar function, and identifying their ligands on the parasite surface, will provide clues on the nature of the interactions that define an efficient parasite–vector system and open up unprecedented opportunities to control the vectorial capacity of anopheline mosquitoes.