bluuebunny/crossref_metadata_2025 huggingface dataset:
Patient positioning in the proton radiotherapy era
Authors: Devicienti Salvatore , Strigari Lidia , D'Andrea Marco , Benassi Marcello , Dimiccoli Vincenzo , Portaluri Maurizio
Published: May 2010

The main hindrance to the diffusion of proton therapy facilities is the high cost for gantry installations. An alternative technical option is provided by fixed-beam treatment rooms, where the patient is rotated and translated in space with a robotic arm solution to enable beam incidence from various angles. The technological efforts based on robotic applications made up to now for patient positioning in proton beam facilities are described here, highlighting their limitations and perspectives.
Current insights in to the pathophysiology of Irritable Bowel Syndrome
Authors: Karantanos Theodoros , Markoutsaki Theofano , Gazouli Maria , Anagnou Nicholas P , Karamanolis Dimitrios G
Published: May 2010

Irritable Bowel Syndrome (IBS) represents a functional disorder of gastrointestinal tract without the presence of an anatomic defect, in which abdominal pain is relieved with defecation and is associated with altered bowel habits.

IBS includes a wide range of symptoms while its pathophysiology is very complicated. Recent studies indicate that the most important mechanisms include visceral sensitivity, abnormal gut motility and autonomous nervous system dysfunction. The interactions between these three mechanisms make bowel's function susceptible to many exogenous and endogenous factors like gastrointestinal flora, feeding and psychosocial factors. Recent data indicate that according to the above mechanisms, the influence of genetic factors and polymorphisms of human DNA in the development of IBS is equally important.
Acoustic VTI modeling with a time-space domain dispersion-relation-based finite-difference scheme
Authors: Liu Yang , Sen Mrinal K.
Published: May 2010

The finite-difference (FD) method is widely used in numerical modeling of wave equations. Conventional FD stencils for space derivatives are usually designed in the space domain. When they are used to solve wave equations, it is difficult to satisfy the dispersion relations exactly. We have designed a spatial FD stencil based on a time-space domain dispersion relation to simulate wave propagation in an acoustic vertically transversely isotropic (VTI) medium. Two-dimensional dispersion analysis and numerical modeling demonstrate that this stencil has greater precision than one used in a conventional FD, when the same number of grid points is used in the calculation of the spatial derivatives. Thus, the spatial FD stencil based on time-space domain dispersion relation can be used to replace a conventional one such that we can achieve greater accuracy with almost no increase in computational cost.
C O2 velocity measurement and models for temperatures up to 200°C and pressures up to 100 MPa
Authors: Han De-Hua , Sun Min , Batzle Micheal
Published: May 2010

Studies on how the velocity of [Formula: see text] is affected by temperature and pressure are important for understanding seismic properties of fluid and rock systems with a [Formula: see text] component. We carried out laboratory experiments to investigate velocity of [Formula: see text] in temperatures ranging from [Formula: see text] and pressures ranging from [Formula: see text], in which [Formula: see text] is in a liquid phase. The results show that under the above conditions, in general, the velocity of [Formula: see text] increases as pressure increases and temperature decreases. Near the critical point ([Formula: see text] and [Formula: see text]), the velocity of [Formula: see text] reaches a minimum and has a complicated behavior with temperature and pressure conditions due to the [Formula: see text] transition between gas and liquid phases. We also developed preliminary empirical models to calculate the velocity of [Formula: see text] based on newly measured data.
Comparison of different BEM+Born series modeling schemes for wave propagation in complex geologic structures
Authors: Yu Geng-Xin , Fu Li-Yun , Yao Zhen-Xing
Published: May 2010

Complex geologic structures generally consist of irregular subregions with piecewise constant properties. Two different boundary-element method (BEM) plus Born-series schemes have been formulated for wave-propagation simulation in such piecewise homogeneous media by incorporating a Born series and boundary integral equations. Both schemes decompose the resulting boundary integral equation matrix into two parts: (1) the self-interaction operator, handled with a fully implicit BEM, and (2) the extrapolation operator, approximated by a Born series. The first scheme associates the self-interaction operator with each boundary itself and interprets the extrapolation operator as cross-interactions between different boundaries in a subregion. The second scheme relates the self-interaction operator toeach subregion itself and expresses the extrapolation operator as cross-interactions between different subregions in a whole model. In the second scheme, the matrix dimension of the resulting boundary integral equation is reduced by eliminating the traction field. Both numerical schemes have been validated by dimensionless frequency responses to a semicircular alluvial valley, compared with the full-waveform BEM numerical solution. We then extended these schemes to a complex fault model by calculating synthetic seismograms to evaluate approximation accuracies. Numerical experiments indicate that the [Formula: see text] series modeling schemes significantly improve computational efficiency, especially for high frequencies and with multisource seismic surveys. The tests also confirmed that the second modeling scheme has a faster convergence but may cause more noise in higher-order iterations than the first scheme.
Feedback Inhibition of Human Scavenger Receptor Class B Type I Gene Expression by Glucocorticoid in Adrenal and Ovarian Cells
Authors: Mavridou Sofia , Venihaki Maria , Rassouli Olga , Tsatsanis Christos , Kardassis Dimitris
Published: May 2010

Scavenger receptor class B type I (SR-BI) facilitates the reverse transport of excess cholesterol from peripheral tissues to the liver via high-density lipoproteins. In steroidogenic tissues, SR-BI supplies cholesterol for steroid hormone production. We show here that the transcription of the human SR-BI gene is subject to feedback inhibition by glucocorticoid in adrenal and ovarian cells. SR-BI mRNA levels were increased in adrenals from corticosterone-insufficient Crh−/− mice, whereas corticosterone replacement by oral administration inhibited SR-BI gene expression in these mice. SR-BI mRNA levels were increased in adrenals from wild-type mice treated with metyrapone, a drug that blocks corticosterone synthesis. Experiments in adrenocortical H295R and ovarian SKOV-3 cells using cycloheximide and siRNA-mediated gene silencing revealed that glucocorticoid-mediated inhibition of SR-BI gene transcription requires de novo protein synthesis and the glucocorticoid receptor (GR). No direct binding of GR to the SR-BI promoter could be demonstrated in vitro and in vivo, suggesting an indirect mechanism of repression of SR-BI gene transcription by GR in adrenal cells. Deletion analysis established that the region of the human SR-BI promoter between nucleotides −201 and −62 is sufficient to mediate repression by glucocorticoid. This region contains putative binding sites for transcriptional repressors that could play a role in SR-BI gene regulation in response to glucocorticoid. In summary, this is the first report showing that glucocorticoid suppress SR-BI expression suggesting that steroidogenic tissues maintain steroid hormone homeostasis by prohibiting SR-BI-mediated high-density lipoprotein cholesterol uptake when the endogenous levels of glucocorticoid are elevated.
Early Postnatal Administration of Growth Hormone Increases Tuberoinfundibular Dopaminergic Neuron Numbers in Ames Dwarf Mice
Authors: Khodr Christina E. , Clark Sara , Bokov Alex F. , Richardson Arlan , Strong Randy , Hurley David L. , Phelps Carol J.
Published: May 2010

Hypothalamic tuberoinfundibular dopaminergic (TIDA) neurons secrete dopamine, which inhibits pituitary prolactin (PRL) secretion. PRL has demonstrated neurotrophic effects on TIDA neuron development in PRL-, GH-, and TSH-deficient Ames (df/df) and Snell (dw/dw) dwarf mice. However, both PRL and PRL receptor knockout mice exhibit normal-sized TIDA neuron numbers, implying GH and/or TSH influence TIDA neuron development. The current study investigated the effect of porcine (p) GH on TIDA neuron development in Ames dwarf hypothalamus. Normal (DF/df) and dwarf mice were treated daily with pGH or saline beginning at 3 d of age for a period of 42 d. After treatment, brains were analyzed using catecholamine histofluorescence, tyrosine hydroxylase immunocytochemistry, and bromodeoxyuridine (BrdU) immunocytochemistry to detect BrdU incorporation. DF/df males and df/df treated with pGH experienced increased (P ≤ 0.01) weight gain compared with those treated with saline. DF/df had greater (P ≤ 0.01) TIDA neuron numbers than df/df, regardless of treatment. TIDA neuron number in pGH-treated df/df was greater (P ≤ 0.01) than in saline-treated df/df. Zona incerta and periventricular dopamine neurons were not affected by treatment or genotype. There was no effect of genotype or treatment on BrdU incorporation in the arcuate nucleus, median eminence, or periventricular region surrounding the third ventricle. Saline-treated df/df experienced decreased (P ≤ 0.05) dentate gyrus BrdU incorporation compared with saline-treated DF/df. In the lateral ventricle, pGH-treated males had greater BrdU immunoreactivity than pGH-treated females. The results show an effect of pGH on TIDA neuron development, although this effect is less potent than that of PRL, and likely GH-induced preservation of TIDA neurons rather than generation of new TIDA neurons via neurogenesis.
Molecular Mechanisms Mediating the Effect of Mono-(2-Ethylhexyl) Phthalate on Hormone-Stimulated Steroidogenesis in MA-10 Mouse Tumor Leydig Cells
Authors: Fan Jinjiang , Traore Kassim , Li Wenping , Amri Hakima , Huang Hongzhan , Wu Cathy , Chen Haolin , Zirkin Barry , Papadopoulos Vassilios
Published: May 2010

Di-(2-ethylhexyl) phthalate, a widely used plasticizer, and its active metabolite, mono-(2-ethylhexyl) phthalate (MEHP), have been shown to exert adverse effects on the reproductive tract in developing and adult animals. As yet, however, the molecular mechanisms by which they act are uncertain. In the present study, we address the molecular and cellular mechanisms underlying the effects of MEHP on basal and human chorionic gonadotropin (hCG)-stimulated steroid production by MA-10 Leydig cells, using a systems biology approach. MEHP induced dose-dependent decreases in hCG-stimulated steroid formation. Changes in mRNA and protein expression in cells treated with increasing concentrations of MEHP in the presence or absence of hCG were measured by gene microarray and protein high-throughput immunoblotting analyses, respectively. Expression profiling indicated that low concentrations of MEHP induced the expression of a number of genes that also were expressed after hCG stimulation. Cross-comparisons between the hCG and MEHP treatments revealed two genes, Anxa1 and AR1. We suggest that these genes may be involved in a new self-regulatory mechanism of steroidogenesis. The MEHP-induced decreases in hCG-stimulated steroid formation were paralleled by increases in reactive oxygen species generation, with the latter mediated by the Cyp1a1 gene and its network. A model for the mechanism of MEHP action on MA-10 Leydig cell steroidogenesis is proposed.
Bone Morphogenetic Protein 2 Acts via Inhibitor of DNA Binding Proteins to Synergistically Regulate Follicle-Stimulating Hormone β Transcription with Activin A
Authors: Ho Catherine C. , Bernard Daniel J.
Published: May 2010

We recently reported that bone morphogenetic proteins (BMPs) 2 and 4 can stimulate FSHβ-subunit (Fshb) transcription alone and in synergy with activins. We further showed that BMP2 signals via the BMP type IA receptor (or activin receptor-like kinase 3) to mediate its effects. However, the intracellular mechanisms through which BMP2 regulates Fshb are unknown. In the current study, we used cDNA microarray analyses (and validation by real-time quantitative RT-PCR) to identify BMP2 target genes in the murine gonadotrope cell line, LβT2. Short-interfering RNA-mediated knockdown, overexpression, and coimmunoprecipitation experiments were used to examine the potential functional roles of selected gene products. Quantitative RT-PCR analysis largely confirmed the results of the array analyses, and inhibitors of DNA binding 1, 2, and 3 (Id1, Id2, and Id3) were selected for functional analyses. Knockdown of endogenous Id2 or Id3, but not Id1, diminished the synergistic effects of BMP2 and activin A on Fshb transcription. Overexpression of Id1, Id2, or Id3 alone had no effect, but all three potentiated activin A or mothers against decapentaplegic homolog (SMAD)3 induction of Fshb transcription. Though the precise mechanism through which Ids produce their effects are not yet known, we observed physical interactions between Id1, Id2, or Id3 and SMAD3. Collectively, the data suggest that BMP2 synergistically regulates Fshb transcription with activins, at least in part, through the combined actions of Ids 2 or 3 and SMAD3.
Hindbrain Catecholamine Neurons Modulate the Growth Hormone But Not the Feeding Response to Ghrelin
Authors: Emanuel Alan J. , Ritter Sue
Published: May 2010

The gastrointestinal peptide, ghrelin, elicits feeding and secretion when administered systemically or centrally. Previous studies have suggested that hypothalamic projections of hindbrain catecholamine neurons are involved in both of these actions of ghrelin. The purpose of this study was to further assess the role of hindbrain catecholamine neurons in ghrelin-induced feeding and GH secretion and to determine the anatomical distribution of the catecholamine neurons involved. We lesioned noradrenergic and adrenergic neurons that innervate the medial hypothalamus by microinjecting the retrogradely transported immunotoxin, saporin (SAP) conjugated to antidopamine-β-hydroxylase (DSAP) into the paraventricular nucleus of the hypothalamus. Controls were injected with unconjugated SAP. We found that the DSAP lesion did not impair the feeding response to central or peripheral ghrelin administration, indicating that these neurons are not required for ghrelin’s orexigenic effect. However, the GH response to ghrelin was prolonged significantly in DSAP-lesioned rats. We also found that expression of Fos, an indicator of neuronal activation, was significantly enhanced over baseline levels in A1, A1/C1, C1, and A5 cell groups after ghrelin treatment and in A1, A1/C1, and A5 cell groups after GH treatment. The similar pattern of Fos expression in catecholamine cell groups after GH and ghrelin and the prolonged GH secretion in response to ghrelin in DSAP rats together suggest that activation of hindbrain catecholamine neurons by ghrelin or GH could be a component of a negative feedback response controlling GH levels.
Ovo1 links Wnt signaling with N-cadherin localization during neural crest migration
Authors: Piloto Sarah , Schilling Thomas F.
Published: May 2010

A fundamental issue in cell biology is how migratory cell behaviors are controlled by dynamically regulated cell adhesion. Vertebrate neural crest (NC) cells rapidly alter cadherin expression and localization at the cell surface during migration. Secreted Wnts induce some of these changes in NC adhesion and also promote specification of NC-derived pigment cells. Here, we show that the zebrafish transcription factor Ovo1 is a Wnt target gene that controls migration of pigment precursors by regulating the intracellular movements of N-cadherin (Ncad). Ovo1 genetically interacts with Ncad and its depletion causes Ncad to accumulate inside cells. Ovo1-deficient embryos strongly upregulate factors involved in intracellular trafficking, including several rab GTPases, known to modulate cellular localization of cadherins. Surprisingly, NC cells express high levels of many of these rab genes in the early embryo, chemical inhibitors of Rab functions rescue NC development in Ovo1-deficient embryos and overexpression of a Rab-interacting protein leads to similar defects in NC migration. These results suggest that Ovo proteins link Wnt signaling to intracellular trafficking pathways that localize Ncad in NC cells and allow them to migrate. Similar processes probably occur in other cell types in which Wnt signaling promotes migration.
The transcription factors Etv4 and Etv5 mediate formation of the ureteric bud tip domain during kidney development
Authors: Kuure Satu , Chi Xuan , Lu Benson , Costantini Frank
Published: May 2010

Signaling by the Ret receptor tyrosine kinase promotes cell movements in the Wolffian duct that give rise to the first ureteric bud tip, initiating kidney development. Although the ETS transcription factors Etv4 and Etv5 are known to be required for mouse kidney development and to act downstream of Ret, their specific functions are unclear. Here, we examine their role by analyzing the ability of Etv4 Etv5 compound mutant cells to contribute to chimeric kidneys. Etv4−/−;Etv5+/− cells show a limited distribution in the caudal Wolffian duct and ureteric bud, similar to Ret−/− cells, revealing a cell-autonomous role for Etv4 and Etv5 in the cell rearrangements promoted by Ret. By contrast, Etv4−/−;Etv5−/− cells display more severe developmental limitations, suggesting a broad role for Etv4 and Etv5 downstream of multiple signals, which are together important for Wolffian duct and ureteric bud morphogenesis.
Special Education Funding Reform: A Review of Impact Studies
Authors: Sigafoos Jeff , Moore Dennis , Brown Don , Green Vanessa A. , O'Reilly Mark F. , Lancioni Giulio E.
Published: May 2010

Various models for funding special education services have been described in the literature. This paper aims at moving the debate concerning special education funding reform beyond the descriptive level by reviewing studies that investigated the impact of various models for funding special education. Systematic searches were conducted of ERIC and PsycINFO to identify studies that investigated the impact, implications, or outcome of one or more special education funding models. Ten studies were identified covering five major funding models. The results showed that the funding reforms investigated in these studies each had associated benefits, but also potential detriments. However, these studies mainly involved indirect outcome measures, often failed to fully assess impact on academic achievement or cost-effectiveness. Results highlight the need for additional research on the impact of special education funding reform.
Teaching Children With Developmental Spelling Difficulties in a One-on-One Context
Authors: Kohnen Saskia , Nickels Lyndsey
Published: May 2010

The aim of this article is to provide clinical and practical guidance for the provision of one-on-one intervention for children with spelling difficulties. We briefly discuss the requirements of theoretically guided assessment and suggest some norm-based assessment tools in this light. The main focus of this article is on teaching children with spelling difficulties in a one-on-one context. Previous research has shown that children present with spelling difficulties of different types and that intervention is most effective when targeted at the specific difficulty. Hence, we outline different interventions for different subtypes of developmental spelling difficulties.
Adaptation of an Interview-Based Protocol to Examine Close Relationships Between Children With Developmental Disabilities and Peers
Authors: Webster Amanda A. , Carter Mark
Published: May 2010

The purpose of this study was to determine whether an interview protocol, based on the Friendship Quality Questionnaire, could be adapted to examine the close relationships of children with developmental disabilities in an inclusive school setting. Twenty-five children with developmental disabilities aged between approximately 5 and 12 years participated and their relationships with 74 peers were examined. Several adaptations to the procedures and interview instrument were evaluated, including gathering interview data from multiple sources and the development of a short form of the interview questionnaire. Overall, the adaptations to procedures used in the current study appeared successful in catering for the wide range of abilities and ages among respondents. This was reflected in the reliability of children's responses, high response rates on the short interview form, and good correspondence between the short and full interview forms. The described adaptations were successful in eliciting information on aspects of children's relationships that might not have been obtained using a traditional interview instrument. This opens the way for further detailed quantitative evaluation of relationships between children with developmental disabilities and peers in inclusive settings.
Muscle strength in elderly adults with GH deficiency after 10 years of GH replacement
Authors: Götherström Galina , Elbornsson Mariam , Stibrant-Sunnerhagen Katharina , Bengtsson Bengt-Åke , Johannsson Gudmundur , Svensson Johan
Published: May 2010

Context

Only few studies have investigated the effects of GH replacement on muscle strength in elderly patients with GH deficiency (GHD).

Objective, design, and patients

In this prospective open-labeled study, the effects of 10 years of GH replacement on muscle strength and neuromuscular function were followed in 24 elderly GHD adults (mean age of 65.2 years; range 61–74 years). Muscle strength was compared with reference values obtained from the background population.

Results

The mean initial GH dose of 0.72 mg/day was lowered to 0.37 mg/day. The mean IGF1 SDS increased from −1.10 at baseline to 1.17 at study end. GH replacement induced a sustained increase in lean body mass and a transient increase in isometric knee flexor strength. Isometric knee extensor strength was reduced after 10 years. However, after correction for age and gender, using observed/predicted value ratios, there was sustained and even progressive increase in most variables reflecting muscle strength. Measurements of neuromuscular function showed unchanged voluntary motor unit activation after 10 years.

Conclusions

Ten years of GH replacement therapy in elderly GHD adults resulted in a transient increase in isometric knee flexor strength, and provided protection from most of the normal age-related decline in muscle performance and neuromuscular function.
Experience-earnings profile and earnings flexibility: A missing piece in some labour market puzzles?
Authors: Gábor I.
Published: May 2010

Drawing on data from 11 successive waves of yearly wage surveys carried out by the Public Employment Service in Hungary from 1992 to 2003, the paper examines, with the use of elementary statistical tools, whether or not earnings fluctuations differ in size across groups of employees with different degrees of schooling and labour market experience, and if they do, whether the observed differentials might be related to differences in the experience-earnings profiles of those groups.Although preliminary, our findings suggest that earnings fluctuations do differ in magnitude across those groups, and that, moreover, their magnitudes vary in positive association with group-specific global and local slopes of the relevant experience-earnings profiles.Assuming that (1) differences in the observed magnitudes of earnings fluctuations are at least partly due to differences in the flexibility/rigidity of the market rates of earnings, and that (2) the flexibility/rigidity of those rates is a determinant of unemployment, it seems reasonable to expect that long-discovered systemic differences in unemployment across groups of employees with different degrees of schooling and experience (and, perhaps, across countries as well) might also be related in part to differences in experience-earnings profiles
Postoperative recurrence of Crohn’s disease, and its prevention
Authors: Lakatos László , Lakatos Péter László
Published: May 2010

A Crohn-betegség krónikus, progresszív kórkép, amely évek alatt az esetek többségében stenotisáló vagy penetráló szövődményekhez vezet. A betegség súlyos aktivitása vagy a szövődmények miatt az esetek mintegy 70%-ában reszekciós műtétre van szükség. A betegség azonban csaknem mindig kiújul, sokszor újabb műtétet igényel. A posztoperatív kiújulás megelőzése nem megoldott, biztosan hatékony szereink nincsenek. Gondos kockázatfelmérés alapján egyedileg kell minden esetben dönteni a kiújulás rizikója és a kezelés előnyeinek, veszélyeinek mérlegelésével. Az alacsony kockázatú esetekben mesalazin adása jön szóba, de a kezelés mellőzése is elfogadható alternatíva. Súlyosabb esetekben immunszuppresszív szer, elsősorban azathioprin adása indokolt. Ígéretesnek tűnik a műtét után három hónapig metronidazol szedése, valamennyi betegcsoportban. A műtét után 6–12 hónappal végzett ileocolonoscopos vizsgálattal objektív képet kaphatunk a betegség endoszkópos súlyosságáról, amelynek prediktív értéke van a későbbi klinikai lefolyás vonatkozásában, ezáltal irányjelzőként szolgálhat a kezelés számára. A legsúlyosabb esetekben az anti-TNF-szerek jelenthetik a hatékony prevenciót és kezelést.
Evaluation of the mitral valve by transthoracic real-time three-dimensional echocardiography
Authors: Nemes Attila , Geleijnse Marcel L. , Soliman Osama I. I. , Vletter Wim B. , McGhie Jackie S. , Forster Tamás , Ten Cate Folkert J.
Published: May 2010

Jelenleg az echokardiográfia a legszéleskörűbben alkalmazott rutin noninvazív diagnosztikus eljárás, amelynek segítségével a mitralis billentyű morfológiája és funkciója jellemezhető. Ennek az összefoglaló jellegű közleménynek a célja az egyik legújabb echokardiográfiás fejlesztés, a transthoracalis real-time háromdimenziós echokardiográfia szerepének bemutatása a mitralis billentyű vizsgálatában.
New trends in the laboratory diagnostics of proteinuria and albuminuria
Authors: Anna V. Oláh , Mátyus János , Sárkány Erika , Horváth Andrea , Fodor Bertalan
Published: May 2010

Újabb klinikai vizsgálatok szerint az albuminuria a cardiovascularis betegségek korai markere. Míg a proteinuria elsősorban a vesefunkció-romlás, az albuminuria a cardiovascularis rizikó paramétere. A régebbi laboratóriumi tesztek érzékenysége nem megfelelő, és a 24 órás vizeletgyűjtés pontatlansága is sok bizonytalanságot okoz. Ezért a mai nemzetközi irányelvek 24 órás gyűjtés helyett a reggeli első vizeletből az albumin/kreatinin (ACR) és protein/kreatinin (PCR) meghatározását javasolják. Klinikai laboratóriumok számára javasolhatók az újabb, nagy érzékenységű immunkémiai vizeletalbumin-reagensek. Az albuminspecifikus tesztcsíkok az albuminuria fokának meghatározására nem elég érzékenyek. A vizeletfehérje-meghatározáshoz szintén léteznek nagy érzékenységű, széles mérési tartományú reagensek, így erre nem alkalmazhatók a szérumfehérje-reagensek (például Biuret). A módszerválasztás sarkalatos pontja, hogy a kalibrátor nemzetközi referensanyagra visszavezethető legyen. Mindezekből következik, hogy egy beteg ACR- vagy PCR-értéke az adott módszert és döntési határértéket alkalmazó ugyanazon laboratóriumban követhető jól. A laboratóriumi leleten az albumin/kreatinin referenciatartományát nemenként kell megadni.
Influence of Variable Interannual Summer Water Temperatures on Brook Trout Growth, Consumption, Reproduction, and Mortality in an Unstratified Adirondack Lake
Authors: Robinson Jason M. , Josephson Daniel C. , Weidel Brian C. , Kraft Clifford E.
Published: May 2010

Stressful water temperatures negatively affect physiological processes in fishes, yet evidence for how elevated temperatures influence population‐level characteristics is rare. An 8‐year field study of brook trout Salvelinus fontinalis in an unstratified Adirondack lake revealed that an aggregate measure of chronically stressful summer water temperatures strongly influenced brook trout population‐level characteristics. We quantified chronic thermal stress using the cumulative degree‐days over which bottom temperatures exceeded a range of thresholds (18–22°C) and found that the strongest relationships were with cumulative degree‐days over 20°C (DD>20). Across years with similar brook trout densities, warmer summer water temperatures resulted in decreased brook trout growth, but growth was not reduced in a year with high water temperatures and low density. Maximum stomach fullness was negatively related to water temperature. Reproductive activity was negatively correlated with stressful summer thermal conditions and was less dependent on female brook trout density. Periods of chronically stressful summer water temperatures resulted in the apparent mortality of age‐2 and older fish during a moderately stressful summer (156 DD>20) and apparent mortality of age‐1 and older fish during the most stressful summer (210 DD>20). In contrast, extensive mortality was not evident in any year‐classes when DD>20 was less than 115. Anthropogenic impacts on the thermal conditions of aquatic ecosystems occur at small (hydrology) and large (climate change) spatial extents, and in situ studies at the margin of an organism's thermal range can provide important insights into changes that will occur if temperatures increase.
Modeling the Influence of Environmental Factors on Spawning Migration Mortality for Sockeye Salmon Fisheries Management in the Fraser River, British Columbia
Authors: Macdonald J. Stevenson , Patterson David A. , Hague Merran J. , Guthrie Ian C.
Published: May 2010

The impact of freshwater environmental factors on spawning migration mortality was modeled to provide a predictive tool for fisheries management of four run timing groups of Fraser River sockeye salmon Oncorhynchus nerka: early Stuart (Stuart Lake), early summer, summer, and late. We tested the significance of different measures of water temperature, discharge, fish abundance, and entry timing for forecasting discrepancies between lower‐river and upriver escapement estimates using multiple regressions of principal component scores. Descriptive discrepancy models (i.e., “management adjustment” models) identified using Akaike's information criterion were consistent with the known biology of each group. For example, temperature and discharge thresholds were selected for early Stuart run discrepancy models, reflecting the extremes in both variables experienced by these early migrants. Predictive discrepancy models were also generated for each run timing group by using the limited number of environmental variables that are available in‐season to fisheries managers. Even predictive discrepancy models using simple environmental metrics of average river temperature, flow, and river entry timing provide a valuable tool for forecasting relative indices of spawning migration mortality. This study provides an example of how environmentally based predictive tools can be used to inform fisheries management decisions and improve the probability of achieving spawning escapement targets.
Ontogenetic Diet Shifts of Juvenile Chinook Salmon in Nearshore and Offshore Habitats of Puget Sound
Authors: Duffy Elisabeth J. , Beauchamp David A. , Sweeting Ruston M. , Beamish Richard J. , Brennan James S.
Published: May 2010

Marine growth and survival of juvenile Chinook salmon Oncorhynchus tshawytscha depend in part on the quality and quantity of prey consumed during this potentially critical life stage; however, little is known about the early marine diet of these fish or factors that affect the diet's variability. We examined the recent (2001–2007) dietary habits of Puget Sound, Washington, Chinook salmon (listed as threatened under the U.S. Endangered Species Act) during their first marine growing season (April–September). Juvenile Chinook salmon initially fed in nearshore marine habitats and then shifted to feed primarily offshore during July–September. Diet composition varied significantly among sampling regions (northern, central, and southern), habitats (nearshore, offshore), years, months, and fish size‐classes. At nearshore sites, insects (all months) and gammarid amphipods (July) were dominant prey sources, whereas in offshore diets decapods (primarily crab larvae; July) and fish (September) were most important. Chinook salmon became increasingly piscivorous as they grew and ate fish with fork lengths up to 51% (nearshore) and 52% (offshore) of predator fork length. At nearshore sites, Chinook salmon fed mainly on larval and juvenile Pacific sand lances Ammodytes hexapterus; offshore, they primarily ate juvenile and older Pacific herring Clupea pallasii. Overall, Chinook salmon had more diverse diets and ate higher‐quality prey (insects) in northern nearshore and central offshore waters, whereas Chinook salmon caught in the southern nearshore and northern offshore waters had a lower proportion of empty stomachs but ate lower‐quality prey (crustaceans). Annual variation in the composition of offshore prey appeared to be determined early in the growing season, suggesting that environmental factors (e.g., climate) affecting marine productivity might produce strong interannual trends in marine survival of Puget Sound Chinook salmon. In addition, the importance of insects as high‐quality prey highlighted the terrestrial link to the marine feeding of Chinook salmon and suggests that shoreline development and land use changes will affect feeding opportunities for these fish in Puget Sound.
Decline of the Shortjaw Cisco in Lake Superior: The Role of Overfishing and Risk of Extinction
Authors: Bronte Charles R. , Hoff Michael H. , Gorman Owen T. , Thogmartin Wayne E. , Schneeberger Philip J. , Todd Thomas N.
Published: May 2010

Recent reviews have further documented the decline of the shortjaw cisco Coregonus zenithicus in Lake Superior. This fish was the most abundant deepwater cisco species in Lake Superior in the early 1920s but presently makes up less than 1% of all deepwater ciscoes (i.e., including shortjaw cisco, bloater C. hoyi, and kiyi C. kiyi) captured in biological surveys. Directed overfishing of deepwater cisco species during the 1930s and again during the mid‐1960s and 1970s has been suggested as the cause of the shortjaw cisco's demise. In this paper, we re‐examined the overfishing hypothesis by using historical and recent survey data to estimate the proportion of the historical commercial fishery landings that comprised shortjaw ciscoes. We developed time series of estimated harvest and relative abundance for all statistical districts in Michigan waters of Lake Superior during 1929–1996, for which aggregate catch and effort data were available but not previously examined. The spatial distribution of the fishery and the relationships of catch to fishing effort were examined for evidence of overfishing. Our analysis suggested that directed overfishing was probably not the cause of shortjaw cisco demise, as this species appeared to be declining in all statistical districts regardless of the intensity of the fishery. A count‐based population viability analysis indicated that quasi‐extinction of the shortjaw cisco is highly probable in the near future. We propose an alternative hypothesis based on the decline of Lake Superior's keystone predator, the lake trout Salvelinus namaycush, which resulted in an expansion of the population of its principal prey, the cisco C. artedi, due to release from predation pressure. Competitive or predation interactions between the cisco and shortjaw cisco may be more likely explanations for the demise of the latter species.
Close Encounters with a Fish Screen III: Behavior, Performance, Physiological Stress Responses, and Recovery of Adult Delta Smelt Exposed to Two‐Vector Flows near a Fish Screen
Authors: Young Paciencia S. , Swanson Christina , Cech Joseph J.
Published: May 2010

The threatened delta smelt Hypomesus transpacificus is vulnerable to more than 2,000 water diversions distributed throughout the Sacramento–San Joaquin Delta system of California. Although fish screen installation should decrease direct losses, the physiological stress associated with exposure to two‐vector flows near a fish screen may increase delta smelt mortality. We measured the swimming performance, screen contact rate, and stress responses of adult delta smelt to handling and simulated screen exposure at 12°C. Results from handling stress and flow stress experiments showed that fish collection, crowding, and transport elicited significant stress responses in delta smelt, as did exposure to the two‐vector flows and a fish screen. However, delta smelt recovered from the cumulative handling stress within 2 h. Combinations of high approach velocity (10 or 15 cm/s) and high sweeping velocity (31 or 62 cm/s) increased the primary stress response (plasma cortisol concentrations) and the number of moribund fish. Fish screens designed to protect the delta smelt population could minimize physiological stress by decreasing approach velocities in areas with high sweeping velocities.
Response of Native and Naturalized Fish to Salmonid Cage Culture Farms in Northern Lake Huron, Canada
Authors: Johnston T. A. , Keir M. , Power M.
Published: May 2010

Cage culture of salmonids has expanded into the northern Great Lakes in recent decades, but the effects of this industry on native and naturalized freshwater fish communities have yet to be fully explored. We compared the relative abundance, community composition, and stable isotope composition of wild fish and selected macroinvertebrates between cage and reference sites in the Manitoulin Island region of northern Lake Huron to test the proposition that cage culture operations have altered their distributions and trophic ecologies. Catch per unit effort was higher at cage sites than at reference sites for both small‐ and large‐bodied fishes, but not for crayfish. Species composition varied significantly between cage and reference sites for the small‐fish assemblage but not for the large‐fish assemblage. The stable isotope ratios (δ13C, δ15N, and δ34S) of dreissenid mussels, crayfish (family Cambaridae), and four species of small‐bodied fish did not differ greatly between the cage and reference sites, suggesting that the direct consumption of farm waste is limited. However, the overlap in isotopic signatures between farm waste and wild biota was considerable. Salmonid cage farms in northern Lake Huron are an attractant to many species of wild fish, but it is not clear how the waste from these farms enters the local food web.
Mitochondrial Variation and Biogeographic History of Chinook Salmon
Authors: Martin Kyle E. , Steele Craig A. , Brunelli Joseph P. , Thorgaard Gary H.
Published: May 2010

The genetic variation of many species in the Northern Hemisphere has been influenced by climatic changes during the Pleistocene Epoch. Phylogeographic studies can help determine intraspecific relationships and postglacial recolonization routes for many of these species, potentially leading to a more complete understanding of how flora and fauna respond to dramatic climate change. We analyzed the variation in the mitochondrial DNA sequences of Chinook salmon Oncorhynchus tshawytscha from California to the Kamchatka Peninsula, Russia, to gain insight into the role of Pleistocene glaciation in the genetic structuring of this species. The geographic distribution of haplotypes revealed high levels of genetic diversity in the Columbia River drainage. Nested clade analysis suggests northward expansion from this area during the late Pleistocene, a hypothesis that is further supported by evidence of demographic growth and population expansion in the northern portion of the species' range. Estimates of the divergence time between two phylogenetic clades are correlated with interglacial periods of the Pleistocene. The data suggest the absence of Chinook salmon from the current northern part of its distribution until the late Pleistocene, when northward expansion from a southern refugium occurred (during an interglacial period), followed by the recent genetic divergence of these northern populations.
Sample Preparation Techniques for Determination of Fish Energy Density via Bomb Calorimetry: An Evaluation Using Largemouth Bass
Authors: Glover David C. , DeVries Dennis R. , Wright Russell A. , Davis Donald A.
Published: May 2010

We evaluated three homogenization and subsampling techniques for preparing fish tissue samples for bomb calorimetry to identify differences in efficiency for estimating fish energy density. We compared (1) drying the whole fish and homogenizing the dried fish tissue, (2) homogenization prior to drying and then drying the subsample of fish tissue, and (3) homogenization after autoclaving to soften the hard structures and then drying a subsample of the homogenized fish tissue. Sample drying time and energy density estimates were compared among techniques across a size range (wet mass = 32–1,080 g) of largemouth bass Micropterus salmoides. Both of the subsampling techniques reduced drying time by about 40% relative to drying the whole fish. All three methods provided statistically similar estimates of largemouth bass energy densities. The autoclave process was most efficient, minimizing both sample preparation time and drying time. Variance of energy density estimates was greater for both subsampling methods compared with the traditional whole‐fish method. Thus, subsampling can decrease sample preparation time for bomb calorimetry but may reduce power to detect differences among variables of interest (e.g., season). Lastly, estimates of energy density for largemouth bass were a function of body mass, suggesting that using a constant energy density in bioenergetics models is not appropriate.
Salmon Carcasses Increase Stream Productivity More than Inorganic Fertilizer Pellets: A Test on Multiple Trophic Levels in Streamside Experimental Channels
Authors: Wipfli Mark S. , Hudson John P. , Caouette John P. , Mitchell Nicole L. , Lessard Joanna L. , Heintz Ron A. , Chaloner Dominic T.
Published: May 2010

Inorganic nutrient amendments to streams are viewed as possible restoration strategies for re‐establishing nutrients and stream productivity throughout the western coast of North America, where salmon runs and associated marine‐derived nutrient subsidies have declined. In a mesocosm experiment, we examined the short‐term (6 weeks) comparative effects of artificial nutrient pellets and salmon carcasses, alone (low and high amounts) and in combination, on stream food webs. Response variables included dissolved nutrient concentrations, biofilm ash‐free dry mass (AFDM) and chlorophyll‐a levels, macroinvertebrate density, growth and body condition of juvenile coho salmon Oncorhynchus kisutch, and whole‐body lipid content of invertebrates and juvenile coho salmon. Most of the response variables were significantly influenced by carcass treatment; the only response variable significantly influenced by fertilizer pellet treatment was soluble reactive phosphorus (SRP) concentration. Ammonium‐nitrogen concentration was the only response variable affected by both (low and high) levels of carcass treatment; all others showed no significant response to the two carcass treatment levels. Significant treatment × time interactions were observed for all responses except nitrate; for most responses, significant treatment effects were detected at certain time periods and not others. For example, significantly higher SRP concentrations were recorded earlier in the experiment, whereas significant fish responses were observed later. These results provide evidence that inorganic nutrient additions do not have the same ecological effects in streams as do salmon carcasses, potentially because inorganic nutrient additions lack carbon‐based biochemicals and macromolecules that are sequestered directly or indirectly by consumers. Salmon carcasses, preferably deposited naturally during spawning migrations, appear to be far superior to inorganic nutrient amendments for sustaining and restoring stream productivity, including fish production, and should be chosen over artificial nutrient additions when feasible and practical.
Evidence-based non-skeletal actions of vitamin D
Authors: Muszkat Patricia , Camargo Marilia Brasilio Rodrigues , Griz Luiz Henrique Maciel , Lazaretti-Castro Marise
Published: May 2010

Vitamin D is a major regulator of mineral homeostasis through its action in the kidney, intestine, bone and parathyroid glands. On these tissues, its active form, calcitriol, acts by binding to a specific nuclear receptor that belongs to the steroid/thyroid hormone receptor family. This receptor, however, has also been identified in several additional human tissues. So, apart from its traditional actions related to calcium, vitamin D and its synthetic analogs are being increasingly recognized for their anti-proliferative, pro-differentiative and immunomodulatory activities. Low levels of vitamin D have been linked to many chronic diseases. Decreased muscle function and increased fall risk in elderly people; prostate, breast and colorectal cancers; diabetes mellitus; and other health problems have been associated to low circulating levels of 25-hydroxyvitamin D. This paper presents an overview of the available scientific evidence for the non-calcemic actions of vitamin D in humans.
Vitamin D deficiency in HIV-infected individuals: one more risk factor for bone loss and cardiovascular disease?
Authors: Conrado Tereza , Miranda-Filho Demócrito de Barros , Bandeira Francisco
Published: May 2010

The epidemiological profile of the HIV virus has undergone substantial modifications with advances in antiretroviral therapy. There has been a sharp decline in morbi-mortality levels of HIV-infected patients, which has resulted in higher survival rates. The HIV seropositive population is living longer and more exposed to chronic complications caused by the disease itself and the prolonged use of antiretrovirals. Initially, metabolic alterations were reported, increasing cardiovascular disease risk. Subsequently, damage on bone metabolism was related. Vitamin D insufficiency has now reached epidemic proportions, even in healthy individuals living in the tropics. Recent data suggest the hypovitaminosis D association with metabolic syndrome, immune diseases, diabetes and hypertension. Little is known regarding the effects of HIV/Aids and its treatment on the metabolism of vitamin D. In HIV-positive patients, factors linked to the virus itself and the use of antiretrovirals may be added to the other causes of hypovitaminosis D.
Post-transplantation osteoporosis
Authors: Kulak Carolina A. Moreira , Borba Victória Z. Cochenski , Kulak Júnior Jaime , Campos Denise Jonhsson , Shane Elizabeth
Published: May 2010

Transplantation is an established therapy for many hematologic disorders as well as for end-stage diseases of the kidney, lung, liver, heart among others. Osteoporosis and a high incidence of fragility fractures have emerged as a complication of organ transplantation. Many factors contribute to the pathogenesis of osteoporosis following organ transplantation. In addition, most patients have some form of bone disease prior to transplantation, which is usually related to adverse effects of end-stage organ failure on the skeleton. This chapter reviews the mechanisms of bone loss that occur both in the early and late post-transplant periods including the contribution of immunosuppressive agents as well as the specific features of bone loss after kidney, lung, liver, cardiac and bone marrow transplantation. Prevention and treatment for osteoporosis in the transplant recipient will also be addressed.