bluuebunny/crossref_metadata_2025 huggingface dataset:
Hemi‐field and full‐field form‐deprivation induce timing changes in multifocalERGresponses in chick
Authors: Schmid Katrina L , Rayner Cassie L , Brown Brian
Published: May 2013

Purpose

In animal models hemi‐field deprivation results in localised, graded vitreous chamber elongation and presumably deprivation induced localised changes in retinal processing. The aim of this research was to determine if there are variations in ERG responses across the retina in normal chick eyes and to examine the effect of hemi‐field and full‐field deprivation on ERG responses across the retina and at earlier times than have previously been examined electrophysiologically.

Methods

Chicks were either untreated, wore monocular full‐diffusers or half‐diffusers (depriving nasal retina) (n = 6–8 each group) from day 8. mfERG responses were measured using the VERIS mfERG system across the central 18.2º× 16.7º (H × V) field. The stimulus consisted of 61 unscaled hexagons with each hexagon modulated between black and white according to a pseudorandom binary m‐sequence. The mfERG was measured on day 12 in untreated chicks, following 4 days of hemi‐field diffuser wear, and 2, 48 and 96 h after application of full‐field diffusers.

Results

The ERG response of untreated chick eyes did not vary across the measured field; there was no effect of retinal location on the N1‐P1 amplitude (p = 0.108) or on P1 implicit time (p > 0.05). This finding is consistent with retinal ganglion cell density of the chick varying by only a factor of two across the entire retina. Half‐diffusers produced a ramped retina and a graded effect of negative lens correction (p < 0.0001); changes in retinal processing were localized. The untreated retina showed increasing complexity of the ERG waveform with development; form‐deprivation prevented the increasing complexity of the response at the 2, 48 and 96 h measurement times and produced alterations in response timing.

Conclusions

Form‐deprivation and its concomitant loss of image contrast and high spatial frequency images prevented development of the ERG responses, consistent with a disruption of development of retinal feedback systems. The characterisation of ERG responses in normal and deprived chick eyes across the retina allows the assessment of concurrent visual and retinal manipulations in this model.
Can the retina alone detect the sign of defocus?
Authors: Schaeffel Frank , Wildsoet Christine
Published: May 2013

In the following point‐counterpoint article, internationally‐acclaimed myopia researchers were challenged to defend the two opposing sides of the topic defined by the title; their contributions, which appear in the order, Point followed by Counterpoint, were peer‐reviewed by both the editorial team and an external reviewer. Independently of the invited authors, the named member of the editorial team provided an Introduction and Summary, both of which were reviewed by the other members of the editorial team. By their nature, views expressed in each section of the Point‐Counterpoint article are those of the author concerned and may not reflect the views of all of the authors.
Form deprivation and lens‐induced myopia: are they different?
Authors: Morgan Ian G. , Ashby Regan S. , Nickla Debora L.
Published: May 2013

In the following point‐counterpoint article, internationally‐acclaimed myopia researchers were challenged to defend the two opposing sides of the topic defined by the title; their contributions, which appear in the
order Point followed by Counterpoint, were peer‐reviewed by both the editorial team and an external reviewer. Independently of the invited authors, the named member of the editorial team provided an Introduction and Summary, both of which were reviewed by the other members of the editorial team. By their nature, views expressed in each section of the Point‐Counterpoint article are those of the author concerned and may not reflect the views of all of the authors.
Does peripheral retinal input explain the promising myopia control effects of corneal reshaping therapy (CRT or ortho‐K) & multifocal soft contact lenses?
Authors: Smith Earl L. , Campbell Melanie C. W. , Irving Elizabeth
Published: May 2013

In the following point‐counterpoint article, internationally‐acclaimed myopia researchers were challenged to defend the two opposing sides of the topic defined by the title; their contributions, which appear in the order Point followed by Counterpoint, were peer‐reviewed by both the editorial team and an external reviewer. Independently of the invited authors, the named member of the editorial team provided an Introduction and Summary, both of which were reviewed by the other members of the editorial team. By their nature, views expressed in each section of the Point‐Counterpoint article are those of the author concerned and may not reflect the views of all of the authors.
Temporal properties of the myopic response to defocus in the guinea pig
Authors: Leotta Amelia J , Bowrey Hannah E , Zeng Guang , McFadden Sally A
Published: May 2013

Purpose

Hyperopic defocus induces myopia in all species tested and is believed to underlie the progression of human myopia. We determined the temporal properties of the effects of hyperopic defocus in a mammalian eye.

Methods

In Experiment 1, the rise and decay time of the responses elicited by hyperopic defocus were calculated in 111 guinea pigs by giving repeated episodes of monocular −4 D lens wear (from 5 to 6 days of age for 12 days) interspersed with various dark intervals. In Experiment 2, the decay time constant was calculated in 152 guinea pigs when repeated periods of monocular −5 D lens‐wear (from 4 days of age for 7 days) were interrupted with free viewing periods of different lengths. At the end of the lens‐wear period, ocular parameters were measured and time constants were calculated relative to the maximum response induced by continuous lens wear.

Results

When hyperopic defocus was experienced with dark intervals between episodes, the time required to induce 50% of the maximum achievable myopia and ocular elongation was at most 30 min. Saturated 1 h episodes took at least 22 h for refractive error and 31 h for ocular length, to decay to 50% of the maximum response. However, the decay was an order of magnitude faster when hyperopic defocus episodes were interrupted with a daily free viewing period, with only 36 min required to reduce relative myopia and ocular elongation by 50%.

Conclusions

Hyperopic defocus causes myopia with brief exposures and is very long lasting in the absence of competing signals. However, this myopic response rapidly decays if interrupted by periods of ‘normal viewing’ at least 30 min in length, wherein ocular growth appears to be guided preferentially by the least amount of hyperopic defocus experienced.
Successful conservative treatment of mandibular fracture after third molar extraction in a patient with osteogenesis imperfecta: case report and clinical considerations
Authors: Herrera‐Calvo G. , García‐Montesinos Perea B. , Saiz Bustillo R.
Published: May 2013

Osteogenesis imperfecta (OI) comprises a heterogeneous group of connective tissue diseases that mainly manifest with bone fragility and skeletal deformity, which also has several metabolic defects that provide surgical and anaesthetic risks to this kind of patients. Moreover, bisphosphonates are an important part of their therapy, and this also involves some surgical considerations. Despite this widespread bone fragility, fractures of the facial bones occur very infrequently with very few cases reported in the literature, and all of them treated surgically. From the best of our knowledge, we describe the first case of a mandibular fracture in a patient with OI successfully treated by closed reduction and elastic maxillomandibular fixation. Some surgical considerations are discussed in this report.
Subxiphoid Approach to Epicardial Implantation of Implantable Cardioverter Defibrillators in Children
Authors: HAYDIN SERTAC , SAYGI MURAT , ERGUL YAKUP , OZYILMAZ ISA , OZTURK ERKUT , AKDENIZ CELAL , TUZCU VOLKAN
Published: May 2013

Background

Epicardial implantation of implantable cardioverter defibrillators (ICDs) is considered in the presence of intracardiac shunt, venous access issue, or small body size. We report our experience with epicardial ICD coil implantation using a minimally invasive method.

Methods

Nine patients who underwent epicardial ICD implantation were included. The median age was 7.4 years (3.9–9.6 years) and the median weight was 15 kg (12–24 kg). Diagnosis at the time of implantation included long QT syndrome (n = 5), catecholaminergic polymorphic ventricular tachycardia (n = 2), hypertrophic cardiomyopathy (n = 1), and fast monomorphic ventricular tachycardia (n = 1). The minimally invasive method involved a subxiphoid incision to place the epicardial pacing leads. The ICD coil was placed in the transverse sinus in four patients using an access path posterior to the heart. The second approach involved a path anterior to the heart to reach the epicardial location posterior to the left atrial appendage in the five remaining patients. No fluoroscopy was used in either approach. The median defibrillation threshold (DFT) at implantation was 7.5 J.

Results

Lower DFTs were observed in the anterior approach (10 J vs 5 J). Appropriate ICD shocks were observed in three patients during the median 18‐month follow‐up period (0.3–28 months). No inappropriate shocks were noted. One patient developed pericardial tamponade 39 days after the procedure and was surgically drained.

Conclusions

Minimally invasive epicardial ICD coil implantation in children with low DFT values is possible. The anterior implantation approach appears superior to the posterior approach.
ADVOCACY COALITIONS IN CRISIS RESOLUTION: UNDERSTANDING POLICY DISPUTE IN THE EUROPEAN VOLCANIC ASH CLOUD CRISIS
Authors: NOHRSTEDT DANIEL
Published: May 2013

Disruptive crises are generally conducive to policy conflict between multiple stakeholders. Following the potentially adversarial nature of crisis resolution, there is a need for theoretical approaches to advance the understanding of the political context in which such disputes evolve. This article explains how the advocacy coalition framework (ACF) can be applied as a theoretical basis for understanding the development and effects of policy conflicts in crisis resolution. Illustrating the ACF as a tool for descriptive policy analysis in this context, the article conducts a case study of the European response to the 2010 volcanic ash cloud crisis, focusing on the nature of the policy subsystem, the role of scientific information, competing crisis narratives, exploitation of resources and venues, and policy change. The concluding section identifies a set of theoretical implications and specifies how the framework can be used by practitioners to mitigate the effects of policy conflicts on crisis resolution.
Commensal anomiid bivalves on Late Cretaceous heteromorph ammonites from south‐west Japan
Authors: Misaki Akihiro , Maeda Haruyoshi , Kumagae Taro , Ichida Masahiro
Published: May 2013

The heteromorph ammonite Pravitoceras sigmoidale from the Upper Cretaceous Seidan Formation (Izumi Group) in south‐west Japan is frequently encrusted by sessile anomiid bivalves. Fossils of P. sigmoidale with anomiids are often concentrated at the top of or just above turbidite sandstones. Projecting retroversal hooks and apertures of P. sigmoidale are usually intact, and some individuals are associated with jaw apparatuses near apertures. Anomiids are found on both sides and ventral peripheries of P. sigmoidale conchs, attached predominantly to body chambers. These modes of occurrence suggest that the encrustation by anomiids occurred not on post‐mortem floating or sunken carcasses but on live conchs and that these organisms were rapidly buried by turbidity current deposits shortly after death. Attachment to both flanks and ventral peripheries of the retroversal hooks may indicate that at least adult individuals of P. sigmoidale did not lie on the sea floor and did not drag their body chambers. It is suggested that fully mature individuals of this ammonite species lived for a long period of time after having formed the retroversal hook because a few generations of anomiids have colonized a single body chamber. Such colonization by anomiids is also observed on Didymoceras awajiense, which is considered to be the closely related ancestral species of P. sigmoidale. This anomiid–heteromorph ammonite commensal relationship might continue to persist in descendants during the course of evolution of these heteromorph ammonites.
Photosynthetic and anatomical responses of Eucalyptus grandis leaves to potassium and sodium supply in a field experiment
Authors: BATTIE‐LACLAU PATRICIA , LACLAU JEAN‐PAUL , BERI CONSTANCE , MIETTON LAURIANE , MUNIZ MARTA R.ALMEIDA , ARENQUE BRUNA CERSÓZIMO , DE CASSIA PICCOLO MARISA , JORDAN‐MEILLE LIONEL , BOUILLET JEAN‐PIERRE , NOUVELLON YANN
Published: May 2013

Although vast areas in tropical regions have weathered soils with low potassium (K) levels, little is known about the effects of K supply on the photosynthetic physiology of trees. This study assessed the effects of K and sodium (Na) supply on the diffusional and biochemical limitations to photosynthesis in Eucalyptus grandis leaves. A field experiment comparing treatments receiving K (+K) or Na (+Na) with a control treatment (C) was set up in a K‐deficient soil. The net CO2 assimilation rates were twice as high in +K and 1.6 times higher in +Na than in the C as a result of lower stomatal and mesophyll resistance to CO2 diffusion and higher photosynthetic capacity. The starch content was higher and soluble sugar was lower in +K than in C and +Na, suggesting that K starvation disturbed carbon storage and transport. The specific leaf area, leaf thickness, parenchyma thickness, stomatal size and intercellular air spaces increased in +K and +Na compared to C. Nitrogen and chlorophyll concentrations were also higher in +K and +Na than in C. These results suggest a strong relationship between the K and Na supply to E. grandis trees and the functional and structural limitations to CO2 assimilation rates.
Constraining 3‐PGwith a new δ13Csubmodel: a test using the δ13Cof tree rings
Authors: WEI LIANG , MARSHALL JOHN D. , LINK TIMOTHY E. , KAVANAGH KATHLEEN L. , DU ENHAO , PANGLE ROBERT E. , GAG PETER J. , UBIERNA NEREA
Published: May 2013

A semi‐mechanistic forest growth model, 3‐PG(PhysiologicalPrinciplesPredictingGrowth), was extended to calculate δ13Cin tree rings. The δ13Cestimates were based on the model's existing description of carbon assimilation and canopy conductance. The model was tested in two ∼80‐year‐old natural stands ofAbies grandis(grand fir) in northern Idaho. We used as many independent measurements as possible to parameterize the model. Measured parameters included quantum yield, specific leaf area, soil water content and litterfall rate. Predictions were compared with measurements of transpiration by sap flux, stem biomass, tree diameter growth, leaf area index and δ13C. Sensitivity analysis showed that the model's predictions of δ13Cwere sensitive to key parameters controlling carbon assimilation and canopy conductance, which would have allowed it to fail had the model been parameterized or programmed incorrectly. Instead, the simulated δ13Cof tree rings was no different from measurements (P > 0.05). The δ13Csubmodel provides a convenient means of constraining parameter space and avoiding model artefacts. This δ13Ctest may be applied to any forest growth model that includes realistic simulations of carbon assimilation and transpiration.
The importance of the infected seed tuber and soil inoculum in transmitting Potato mop‐top virus to potato plants
Authors: Davey T. , Carnegie S. F. , Saddler G. S. , Mitchell W. J.
Published: May 2013

Potato mop‐top virus (PMTV), the cause of spraing in potato tubers, is transmitted by Spongospora subterranea, the cause of powdery scab, and by planting infected seed tubers. This study was undertaken to determine the relative importance of these sources of infection in seed potato production in Scotland. The transmission of PMTV from tested seed tubers to daughter plants was examined over 2 years and six cultivars. The development of foliar symptoms varied with year and cultivar. Infection of daughter tubers derived from PMTV‐infected seed tubers was more prevalent on plants affected by foliar symptoms than those without symptoms. The rate of transmission of PMTV from infected seed tubers to daughter tubers ranged from 18 to 54%. Transmission was affected by cultivar and by origin of seed tubers used for a cultivar, but not by a cultivar's sensitivity to PMTV infection. The incidence of PMTV in daughter tubers of cv. Cara grown from seed potatoes from one source (common origin) by more than 25 seed producers was examined over two successive generations. The incidence of PMTV in daughter tubers was not correlated with that in the seed tubers but appeared to be strongly associated with soil inoculum. The incidence of PMTV was correlated with powdery scab in those crops in which both were present. There was some evidence from soil tests conducted in 2006 using a tomato bait plant and real‐time RT‐PCR that planting PMTV‐infected seed potatoes could increase the risk of introducing the virus into land not infested by PMTV.
Assessing Regulatory Participation by Health Professionals: A Study of State Health Rulemaking
Authors: Yackee Susan Webb
Published: May 2013

Do health and health policy professionals (HHPPs) participate in the formation of agency health regulations? Passage of the Patient Protection and Affordable Care Act (ACA) of 2010 has necessitated the writing of many health‐related national and state regulations. This article examines the participation patterns of HHPPs during rulemaking to gain insights that may be transferable to future health‐related administrative decision making. The author suggests that the mix of public participants active during rulemaking has implications for health policy outputs. This proposition is tested using data drawn from 39 state health regulations and survey data from more than 380 participants and 23 interviews with agency officials. The author finds that HHPPs participate across the majority of the sample regulations, and when their activity across a rule increases, so does participant satisfaction with regulatory outcomes. More broadly, the results suggest a desire for even greater participation by HHPPs in future health‐related rulemaking.
Barriers and facilitators of sports in Dutch Paralympic athletes: An explorative study
Authors: Jaarsma E. A. , Geertzen J. H. B. , de Jong R. , Dijkstra P. U. , Dekker R.
Published: May 2013

The purpose of this study was to gain insight in barriers and facilitators of sports in paralympic athletes. An online questionnaire was distributed through the Netherlands Olympic Committee and National Sports Confederation to determine personal and environmental barriers and facilitators of sports participation. The International Classification of Functioning, Disability and Health model and theory of planned behavior were used to respectively categorize the results in environmental and personal factors, and attitude, subjective norm and perceived behavioral control. Seventy‐six Dutch Paralympic athletes completed the questionnaire (51% response rate). Barriers and facilitators experienced by ambulant and wheelchair athletes were compared. Most frequently mentioned personal barrier was dependency of others (22%), while most frequently mentioned environmental barrier was lack of sports facilities (30%). Wheelchair athletes mentioned more barriers (median = 3, interquartile range: 0.5–6), than ambulant athletes (median = 1.0,interquartile range:0.0–3.0, P = 0.023). One‐third of the athletes did not experience any barriers. Most frequently mentioned personal facilitators to initiate sports participation were fun (78%), health (61%), and competition (53%). Most frequently mentioned environmental facilitator was social support (40%). This study indicated that barriers of sport were mostly environmental, while facilitators were usually personal factors. Attitude and subjective norm were considered the most important components for intention to participation in sports. The facilitators outweighed the barriers and kept the athletes being active in sports.
Relationship between aerobic endurance training and dynamic cerebral blood flow regulation in humans
Authors: Ichikawa D. , Miyazawa T. , Horiuchi M. , Kitama T. , Fisher J. P. , Ogoh S.
Published: May 2013

The incidence of orthostatic intolerance is elevated in endurance‐trained individuals. We sought to test the hypothesis that aerobic endurance training is associated with an attenuated control of the cerebral vasculature. Endurance trained (ET, n = 13) and age‐matched untrained (UT, n = 11) individuals (peak O2 consumption, mean ± SEM; 63 ± 1 vs 42 ± 1 mL/min/kg, P < 0.05) were examined while supine and seated upright. Dynamic cerebral autoregulation (CA) was assessed by calculation of the rate of regulation (RoR) from the arterial blood pressure (ABP) and middle cerebral artery (MCA) mean blood velocity (Vmean) responses to a bilateral thigh cuff release, which evoked a transient hypotension. Cerebral oxygenation (oxyhemoglobin; HbO2) was determined with near‐infrared spectroscopy. When seated upright, cuff release evoked a greater decrease in ABP (P < 0.001), MCA Vmean (P = 0.096) and HbO2 (P < 0.001) in ET compared with UT. However, RoR was similar in ET and UT individuals while seated upright (to 0.193 ± 0.039 vs 0.129 ± 0.029/s, P > 0.05), and there was no significant difference in the relative change in RoR from the supine to upright positions (ΔRoR: −65 ± 7 and −69 ± 7%, for ET and UT, respectively). These findings suggest that aerobic endurance training is not associated with an attenuation in dynamic CA.
Thegndgene ofBuchneraas a new, effectiveDNAbarcode for aphid identification
Authors: CHEN RUI , JIANG LI‐YUN , LIU LIN , LIU QING‐HUA , WEN JUAN , ZHANG RUI‐LING , LI XING‐YI , WANG YUAN , LEI FU‐MIN , QIAO GE‐XIA
Published: May 2013

DNAbarcoding uses a standardDNAsequence to facilitate species identification. Although theCOIgene has been adopted as the standard,COIalone is imperfect due to several shortcomings. The primary endosymbiont of aphids,Buchnera, has higher evolutionary rates and interspecies divergence than its co‐diverging aphid hosts, making it a potential tool for resolving the ambiguities in aphid taxonomy. We compared the effectiveness of employing two differentDNAregions,gndandCOI, for the discrimination of over 100 species of aphids. The mean interspecific divergence of thegndregion was significantly higher than the mean intraspecific variation; there were nearly nonoverlapping distributions between the intra‐ and interspecific samples. In contrast,COIshowed a lower interspecific divergence, which led to difficulties in identifying closely related species. Our results show thatgndcan identify species in the Aphididae, which suggests that thegndregion ofBuchnerais a potentially effective barcode for aphid species identification. We also recommend the 2‐locus combination ofgnd+COIas the aphid barcode. This will provide a universal framework for the routine use ofDNAsequence data to identify specimens and contribute toward the discovery of overlooked species of aphids.
Multifocal periostitis as a complication of chronic use of voriconazole in a lung transplant recipient
Authors: Tedja R. , El‐Sherief A. , Olbrych T. , Gordon S.
Published: May 2013

Fungal infections are common in solid organ transplantation. An increasing number of transplant recipients receive antifungal therapy for prolonged duration owing to invasive fungal infections. Herein, we describe a diagnosis of periostitis as a complication of chronic use of voriconazole in a lung transplant recipient. The patient was diagnosed with probable pulmonary aspergillosis and was treated with oral voriconazole for a total of 9 months. Evidence of multifocal periostitis was observed in the axial and appendicular skeleton. Early recognition of this phenomenon is important to prevent unnecessary tests and procedures. Prompt discontinuation of voriconazole should result in improvement of symptoms.
A tandem Kunitz protease inhibitor (KPI106)–serine carboxypeptidase (SCP1) controls mycorrhiza establishment and arbuscule development in Medicago truncatula
Authors: Rech Stefanie S. , Heidt Sven , Requena Natalia
Published: May 2013

Plant proteases and protease inhibitors are involved in plant developmental processes including those involving interactions with microbes. Here we show that a tandem between a Kunitz protease inhibitor (KPI106) and a serine carboxypeptidase (SCP1) controls arbuscular mycorrhiza development in the root cortex of Medicago truncatula. Both proteins are only induced during mycorrhiza formation and belong to large families whose members are also mycorrhiza‐specific. Furthermore, the interaction between KPI106 and SCP1 analysed using the yeast two‐hybrid system is specific, indicating that each family member might have a defined counterpart. In silico docking analysis predicted a putative P1 residue in KPI106 (Lys173) that fits into the catalytic pocket of SCP1, suggesting that KPI106 might inhibit the enzyme activity by mimicking the protease substrate. In vitro mutagenesis of the Lys173 showed that this residue is important in determining the strength and specificity of the interaction. The RNA interference (RNAi) inactivation of the serine carboxypeptidase SCP1 produces aberrant mycorrhizal development with an increased number of septated hyphae and degenerate arbuscules, a phenotype also observed when overexpressing KPI106. Protease and inhibitor are both secreted as observed when expressed in Nicotiana benthamiana epidermal cells. Taken together we envisage a model in which the protease SCP1 is secreted in the apoplast where it produces a peptide signal critical for proper fungal development within the root. KPI106 also at the apoplast would modulate the spatial and/or temporal activity of SCP1 by competing with the protease substrate.
Timely expression of the Arabidopsis stoma‐fate master regulator MUTE is required for specification of other epidermal cell types
Authors: Triviño Magdalena , Martín‐Trillo Mar , Ballesteros Isabel , Delgado Dolores , de Marcos Alberto , Desvoyes Bénédicte , Gutiérrez Crisanto , Mena Montaña , Fenoll Carmen
Published: May 2013

Epidermal differentiation in Arabidopsis thaliana aerial organs involves stomatal lineage development. Lineages derive from meristemoids, which arise from asymmetric divisions of protodermal cells. Each meristemoid divides repeatedly in an inward spiral before it transits to a guard mother cell (GMC) that produces the stoma, leaving a trail of surrounding stomatal lineage ground cells (SLGCs) that eventually differentiate into endoreplicated pavement cells. MUTE is a bHLH transcription factor that is expressed in late meristemoids and drives their transition to GMCs. Loss‐of‐function mute mutants are stomata‐less dwarf plants with arrested lineages, in which stunted putative SLGCs surround a halted meristemoid. We analysed MUTE functions using a chemically inducible system for mute‐3 complementation based on conditional MUTE expression in its normal domain. Continuous induction from germination produced stomata‐bearing, normal‐sized plants with viable mute‐3 seeds. In 2‐week‐old mute‐3 cotyledons, meristemoids appeared to retain their identity and synchronously formed stomata in response to induced MUTE expression. However, arrested SLGCs were not complemented: many produced stomata, leading to stomatal clusters, and others remained unexpanded and diploid. In contrast, non‐lineage pavement cells, which are under‐endoreplicated in mute‐3, expanded and increased their ploidy level upon induction, showing that the lack of response of SLGCs is specific to this arrested cell type. Leaf phenotypic mosaics include wild‐type lineages and adjacent mute‐3 lineages, whose meristemoids and putative SLGCs remained arrested, indicating that the role of MUTE in SLGC fate is strictly lineage‐autonomous. These results show that timely MUTE expression is essential to prevent stomatal fate in SLGCs and to promote their differentiation as pavement cells.
Arv1 Regulates PM and ER Membrane Structure and Homeostasis But is Dispensable for Intracellular Sterol Transport
Authors: Georgiev Alexander G. , Johansen Jesper , Ramanathan Vidhya D. , Sere Yves Y. , Beh Christopher T. , Menon Anant K.
Published: May 2013

Synopsis

The ER membrane protein Arv1 has been implicated in intracellular sterol transport. We report that the retrograde and anterograde movement of sterols between the ER and PM in Saccharomyces cerevisiae is unaffected by Arv1 deficiency. Instead, we find that arv1 cells display altered ER morphology and PM lipid bilayer organization, and express tail‐anchored proteins at almost undetectable levels. Our results suggest that Arv1 plays a role in membrane homeostasis through its effect on the biogenesis of tail‐end membrane proteins.
IMAGING DIAGNOSIS–PULMONARY‐TRACHEOBRONCHIAL PROLAPSE IN A NEW CALEDONIAN GIANT GECKO (RHACODACTYLUS LEACHIANUS)
Authors: Hoey Seamus , Keller Dominique , Chamberlin Tamara , Pinkerton Marie , Waller Kenneth , Drees Randi
Published: May 2013

A 3‐year‐old male New Caledonian giant gecko, or Leach's gecko (Rhacodactylus leachianus) presented with acute lethargy and coelomic distention. Findings from survey radiographs and an upper gastrointestinal tract contrast study were consistent with severe aerophagia, a collapsed left lung, and hyperinflation of the right lung due to suspected bronchial obstruction. The gecko was treated with conservative medical management, but was found dead 5 days after presentation. Necropsy findings showed intussusception of the proximal left lung into the left mainstem bronchus and trachea.
EPENDYMAL AND PERIVENTRICULAR MAGNETIC RESONANCE IMAGING CHANGES IN FOUR DOGS WITH CENTRAL NERVOUS SYSTEM BLASTOMYCOSIS
Authors: Bentley R. Timothy , Reese Michael J. , Heng Hock Gan , Lin Tsang Long , Shimonohara Nozomi , Fauber Amy
Published: May 2013

Rapid detection of central nervous system (CNS) involvement is important for dogs with blastomycosis, as this can affect antifungal drug selection and has been associated with an increased risk of death. Previous reports describing magnetic resonance imaging (MRI) characteristics of canine CNS blastomycosis primarily identified mass lesions. The purpose of this retrospective study was to determine whether other MRI characteristics of CNS blastomycosis may also occur. Medical records of the Purdue University Veterinary Teaching Hospital were searched and four dogs met inclusion criteria. Magnetic resonance imaging characteristics included periventricular edema, periventricular and meningeal contrast enhancement, and ventriculomegaly. Periventricular lesions most commonly involved the rostral horn of the lateral ventricles and the third ventricle. Increased meningeal contrast enhancement involved the cerebrum, thalamus, sella turcica, and brainstem. Findings indicated that, in addition to mass lesions, MRI characteristics of periventricular hyperintensity, contrast enhancement, and ventriculomegaly may also occur in dogs with CNS blastomycosis.
IMAGING DIAGNOSIS—CONVENTIONAL AND FUNCTIONAL MAGNETIC RESONANCE IMAGING OF A BRAIN ABSCESS IN A GOAT
Authors: Dennler Matthias , Carrera Inés , Beckmann Katrin , Ritz Julia , Rütten Maja , Kircher Patrick R.
Published: May 2013

A 2‐month‐old female goat was presented for depressed mental status and multifocal central neurologic signs 3 weeks after hot‐iron disbudding. Conventional magnetic resonance imaging (MRI) findings included a large intra axial mass in the left frontal lobe that was T2 hyperintense and T1 hypointense centrally with a contrast‐enhancing peripheral capsule and perilesional T2 hyperintensity. A restrictive pattern was present in diffusion‐weighted imaging. Magnetic resonance spectroscopy demonstrated an increased amount of succinate, acetate, amino acids, lipids; minimal amounts of lactate; and decreased amounts of N‐acetyl aspartate and choline. A cerebral abscess due to Trueperella pyogenes was confirmed from necropsy and tissue culture.
Poly-(3)hexylthiophene nanowire networks for versatile fabrication of bulk heterojunctions with increased active volume
Authors: Kramer Theodore J. , Chew Annabel R. , Schiros Theanne , Kymissis Ioannis , Herman Irving P.
Published: May 2013

Spontaneous demixing of poly-(3)hexylthiophene (P3HT) and polystyrene (PS) generates a dense array of crystalline P3HT nanowires embedded in a PS matrix. The PS phase is subsequently removed, to form a network of P3HT nanowires with a greatly enhanced surface area-to-volume ratio relative to a planar P3HT film. Photovoltaic devices fabricated from these networks backfilled with either organic ([6,6]-phenyl-C61-butyric acid methyl ester (PCBM)) or inorganic (cadmium selenide (CdSe) nanocrystals) material have dramatically increased short-circuit current and power conversion efficiencies relative to planar-bilayer-prepared devices, with increases of ∼8× and ∼3× for PCBM and CdSe nanocrystals, respectively, suggesting that these devices have increased P3HT active volume. This two-step backfill technique can produce nanostructured all-organic and hybrid organic/inorganic bulk heterojunction structures that cannot be formed with traditional one-step casting methods.
A study of IMRT planning parameters on planning efficiency, delivery efficiency, and plan quality
Authors: Mittauer Kathryn , Lu Bo , Yan Guanghua , Kahler Darren , Gopal Arun , Amdur Robert , Liu Chihray
Published: May 2013

Purpose

: To improve planning and delivery efficiency of head and neck IMRT without compromising planning quality through the evaluation of inverse planning parameters.

Methods

: Eleven head and neck patients with pre‐existing IMRT treatment plans were selected for this retrospective study. The Pinnacle treatment planning system (TPS) was used to compute new treatment plans for each patient by varying the individual or the combined parameters of dose/fluence grid resolution, minimum MU per segment, and minimum segment area. Forty‐five plans per patient were generated with the following variations: 4 dose/fluence grid resolution plans, 12 minimum segment area plans, 9 minimum MU plans, and 20 combined minimum segment area/minimum MU plans. Each plan was evaluated and compared to others based on dose volume histograms (DVHs) (i.e., plan quality), planning time, and delivery time. To evaluate delivery efficiency, a model was developed that estimated the delivery time of a treatment plan, and validated through measurements on an Elekta Synergy linear accelerator.

Results

: The uncertainty (i.e., variation) of the dose‐volume index due to dose calculation grid variation was as high as 8.2% (5.5 Gy in absolute dose) for planning target volumes (PTVs) and 13.3% (2.1 Gy in absolute dose) for planning at risk volumes (PRVs). Comparison results of dose distributions indicated that smaller volumes were more susceptible to uncertainties. The grid resolution of a 4 mm dose grid with a 2 mm fluence grid was recommended, since it can reduce the final dose calculation time by 63% compared to the accepted standard (2 mm dose grid with a 2 mm fluence grid resolution) while maintaining a similar level of dose‐volume index variation. Threshold values that maintained adequate plan quality (DVH results of the PTVs and PRVs remained satisfied for their dose objectives) were 5 cm2 for minimum segment area and 5 MU for minimum MU. As the minimum MU parameter was increased, the number of segments and delivery time were decreased. Increasing the minimum segment area parameter decreased the plan MU, but had less of an effect on the number of segments and delivery time. Our delivery time model predicted delivery time to within 1.8%.

Conclusions

: Increasing the dose grid while maintaining a small fluence grid allows for improved planning efficiency without compromising plan quality. Delivery efficiency can be improved by increasing the minimum MU, but not the minimum segment area. However, increasing the respective minimum MU and/or the minimum segment area to any value greater than 5 MU and 5 cm2 is not recommended because it degrades plan quality.
Optimization of convergent collimators for pixelated SPECT systems
Authors: Capote Ricardo M. , Matela Nuno , Conceição Raquel C. , Almeida Pedro
Published: May 2013

Purpose:

The optimization of the collimator design is essential to obtain the best possible sensitivity in single photon emission computed tomography imaging. The aim of this work is to present a methodology for maximizing the sensitivity of convergent collimators, specifically designed to match the pitch of pixelated detectors, for a fixed spatial resolution value and to present some initial results using this approach.

Methods:

Given the matched constraint, the optimal collimator design cannot be simply found by allowing the highest level of septal penetration and spatial resolution consistent with the imposed restrictions, as it is done for the optimization of conventional collimators. Therefore, an algorithm that interactively calculates the collimator dimensions, with the maximum sensitivity, which respect the imposed restrictions was developed and used to optimize cone and fan beam collimators with tapered square‐shaped holes for low (60–300 keV) and high energy radiation (300–511 keV). The optimal collimator dimensions were locally calculated based on the premise that each hole and septa of the convergent collimator should locally resemble an appropriate optimal matched parallel collimator.

Results:

The optimal collimator dimensions, calculated for subcentimeter resolutions (3 and 7.5 mm), common pixel sizes (1.6, 2.1, and 2.5 mm), and acceptable septal penetration at 140 keV, were approximately constant throughout the collimator, despite their different hole incidence angles. By using these input parameters and a less strict septal penetration value of 5%, the optimal collimator dimensions and the corresponding mass per detector area were calculated for 511 keV. It is shown that a low value of focal distance leads to improvements in the average sensitivity at a fixed source‐collimator distance and resolution. The optimal cone beam performance outperformed that of other optimal collimation geometries (fan and parallel beam) in imaging objects close to the collimator surface.

Conclusions:

These results demonstrate the potential of this kind of optimal convergent collimators for the use in small field of view imaging applications.
Magnetothermoacoustics from magnetic nanoparticles by short bursting or frequency chirped alternating magnetic field: A theoretical feasibility analysis
Authors: Piao Daqing , Towner Rheal A. , Smith Nataliya , Chen Wei R.
Published: May 2013

Purpose:

To propose an alternative method of thermoacoustic wave generation based on heating of magnetic nanoparticles (MNPs) using alternating magnetic field (AMF).

Methods:

The feasibility of thermoacoustic wave generation from MNPs by applying a short‐burst of AMF or a frequency‐modulated AMF is theoretically analyzed. As the relaxation of MNPs is strongly dependent upon the amplitude and frequency of AMF, either an amplitude modulated, fixed frequency AMF (termed time‐domain AMF) or a frequency modulated, constant amplitude AMF (termed frequency‐domain AMF) will result in time‐varying heat dissipation from MNPs, which has the potential to generate thermoacoustic waves. Following Rosensweigˈs model of specific power loss of MNPs in a steady‐state AMF, the time‐resolved heat dissipations of MNPs of superparamagnetic size when exposed to a short bursting of AMF and/or to a linearly frequency chirped AMF are derived, and the resulted acoustic propagation is presented. Based on experimentally measured temperature‐rise characteristics of a superparamagnetic iron‐oxide nanoparticle (SPION) matrix in a steady‐state AMF of various frequencies, the heat dissipations of the SPION under time‐domain and frequency‐domain AMF configurations that could have practical utility for thermoacoustic wave generation are estimated.

Results:

The initial rates of the temperature‐rise of the SPION matrix were measured at an iron‐weight concentration of 0.8 mg/ml and an AMF frequency of 88.8 kHz to 1.105 MHz. The measured initial rates of temperature‐rise were modeled by Rosensweigˈs theory, and projected to 10 MHz AMF frequency, at which a 1μs bursting corresponding to a 1.55 mm axial resolution of acoustic detection could contain 10 complete cycles of AMF oscillation and the power dissipation is approximately 84 times of that at 1 MHz. Exposing the SPION matrix to a 1 μs bursting of AMF at 10 MHz frequency and 100 Oe field intensity would produce a volumetric heat dissipation of 7.7 μJ/cm3 over the microsecond duration of the AMF burst. If the SPION matrix is exposed to a 1 ms long AMF train at 100 Oe field intensity that chirps linearly from 1 to 10 MHz, the volumetric heat dissipation produced over each 2π phase change of the AMF oscillation is estimated to increase from 0.15 to 1.1 μJ/cm3 within the millisecond duration of the chirping of AMF.

Conclusions:

The heat dissipations upon SPION (∼1 mg/ml iron‐weight concentration) by a 1μs bursting of 100 Oe AMF at 10 MHz and a 1 ms train of 100 Oe AMF that chirps linearly from 1 to 10 MHz were estimated to determine the potential of thermal‐acoustic wave generation. Although thermoacoustic wave generation from MNPs by time‐ or frequency‐domain AMF applications is predicted, the experimental generation of such a wave remains challenging.
Neuromechanical assessment of lidocaine test block in spastic lower limbs
Authors: Buffenoir Kévin , Decq Philippe , Lambertz Daniel , Perot Chantal
Published: May 2013

The objective of this study was to quantify in spastic lower limbs the changes in reflex EMGs and in ankle stiffness after a lidocaine block of the soleus nerve to better understand physiological effects of lidocaine. Twenty patients were prospectively included and assessed before and after lidocaine block of the soleus nerve. We studied clinical and neuromechanical parameters of the triceps surae, including quantification of the maximum Hoffmann’s reflex (Hmax) and tendinous reflex (T) normalized to the maximum direct motor response (Mmax), and passive ankle stiffness assessed by sinusoidal length perturbations. All patients whatever the aetiology of spasticity were improved in clinical parameters of spasticity after the block (62% reduction of the Ashworth score, 85% reduction of stretch reflex scores, increased score on the Physicians’ Rating Scale). All patients presented a reduction of the Hmax–Mmax ratio (mean reduction of 67%) and the T–Mmax ratio (82%). Ankle stiffness was decreased by an average of 23%. Measured stiffness was correlated with the Ashworth score and the T–Mmax ratio. Relatively greater change in the T reflex than in the H reflex suggests that lidocaine block reduces hyperreflexia not only by interfering with generation of afferent volleys in the injected nerve, but also probably by altering generation of the volleys at the level of muscle spindles in the affected spastic muscles, presumably by blocking the transmission along gamma-efferent fibers.
Effect of coarse content on shear behavior of unsaturated coarse granular soils
Authors: Zhao H.F. , Zhang L.M.
Published: May 2013

The effects of coarse content on the microstructure, soil-water characteristics, shearing behavior, and critical state characteristics of three types of unsaturated coarse granular soil with different coarse contents are investigated in an integrated manner through an extensive laboratory test program. The tests were performed on samples with the same void ratio of 0.62. As the coarse content increases, the pore-size distribution of the soil changes from unimodal to bimodal. Accordingly, the soil-water characteristic curve (SWCC) changes from unimodal to bimodal. The whole drainage process of the bimodal SWCC is divided into four stages based on the role of the pore water. The contribution of suction to the peak state parameters and critical state parameters, except for the intercept of the critical state line in the stress plane (μ(s)) of a bimodal soil, reaches its maximum in the first drainage region. The pore water in the two pore series of a bimodal soil contributes to the shear strength differently during the desaturation process. Hence, the variations of the maximum dilatancy and the shear strength parameters with degree of saturation are highly nonlinear and μ(s) shows bimodal features. The contributions of suction to the shear strength parameters decrease with increasing coarse content.
Seismic response of single-storey buildings with flexible diaphragms
Authors: Humar Jagmohan , Popovski Marjan
Published: May 2013

The roof framing in single-storey buildings with large foot prints, generally used for commercial, educational, or institutional purposes, often consists of a flexible steel deck or wood panel diaphragm. Resistance to seismic lateral loads is provided by steel bracings, masonry shear walls, concrete shear walls, wood panel shear walls, or cold formed wall systems. The response of such buildings to seismic loads is strongly affected by the flexibility of the roof diaphragm. Diaphragm flexibility alters the manner in which the inertia forces, shears, and bending moments are distributed along the length of the diaphragm. In addition, it causes a significant increase in the ductility demand on the lateral load resisting system that is expected to be strained into the inelastic range under the design earthquake. Results of a study on the linear and nonlinear seismic response of buildings with flexible diaphragms are presented.
Duodenal application of Li+ in a submaximal therapeutic dose inhibits exocrine pancreatic secretion and modulates gastro-duodenal myoelectrical activity in a conscious pig model
Authors: Naughton Violetta , Hedemann Mette S. , Naughton Patrick J. , McSorley Emeir , Laerke Helle N.
Published: May 2013

This study tested whether duodenal application of lithium inhibits gastroduodenal motility, and whether it suppresses secretion from the exocrine pancreas. Five suckling pigs, 16–18 days old, were surgically fitted with 3 serosal electrodes on the wall of the gastric antrum and the duodenum for electromyography of smooth muscles, and with a pancreatic duct catheter and a duodenal T-cannula for collection and re-entrant flow of pancreatic juice. After the recovery period, on alternative days, each animal was tested once with an intraduodenal infusion of Li+ (100 mmol·L–1C3H5LiO3,10 mL·kg−1·h−1) for 1 h, and once with an intraduodenal infusion of NaCl (154 mM, 10 ml·kg−1·h−1), also for 1 h, with the first treatment, i.e., Li+ or NaCl, randomly assigned. Individual pigs served as their own controls, with data recorded prior to a treatment being used as the baseline. Li+ increased the duration of quiescence (P < 0.05) and activity phase (P < 0.05) in the antrum, thus increasing (P < 0.05) the duration of antral myoelectrical cycles. Li+ shortened (P < 0.05) phase I, but it did not affect phase II or phase III or the MMC in the duodenum. Li+ inhibited pancreatic juice outflow as well as pancreatic enzyme and bicarbonate output (P < 0.05 for all pancreatic parameters).