bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Lipid Source and Concentration on Somatic Growth of Juvenile Green Sea Urchins, Strongylocentrotus droebachiensis
Authors: Kennedy Edward J. , Robinson Shawn M. C. , Parsons G. Jay , Castell John D.
Published: August 2007

Supplying juvenile sea urchins with an abundant supply of resources and essential nutrients for growth will facilitate somatic growth and, hence, improve the success of the sea urchin aquaculture industry. Lipids are essential in physical processes such as membrane production and are a concentrated source of energy. This study, using prepared diets, tested the effects of lipid sources containing different major fatty acids (i.e., n‐3 and/or n‐6) (Part 1) and lipid concentration (i.e., 1, 3, 7, and 10%) (Part 2) on the somatic (i.e., test or shell) growth of two size cohorts (7.0‐ and 15.3‐mm average initial test diameter [TD]) of juvenile green sea urchins, Strongylocentrotus droebachiensis. The growth of the sea urchins fed prepared diets was compared to the growth of sea urchins fed a kelp reference diet, Laminaria longicruris. After both feeding trials, the kelp‐fed sea urchins had superior test growth and were more similar in physical appearance to wild sea urchins (i.e., test color, spine length, and gonad color). The sea urchins fed the prepared diets had pale test color, short, stubby spines, and large, pale‐colored gonads compared to wild sea urchins. The smaller cohort of sea urchins grew at a faster rate, but growth patterns for both cohorts were similar. The juveniles fed the prepared diets (in both feeding trials) had high initial growth rates that decreased after approximately 100 d compared to the kelp‐fed juveniles. Differences in test growth were not shown to be affected by sea urchin size (i.e., similar results for both cohorts) or by differences in dietary lipid sources (i.e., the presence of n‐3 and/or n‐6 fatty acids). However, the sea urchins fed diets with lower lipid concentration (≤3%) had larger average TDs than those fed diets with higher lipid concentrations (≥7%). Differences in test growth and physical appearance among those fed the prepared diets and kelp may have been because of nutritional deficiencies in the prepared diets.
Skeletal and Pigmentation Defects following Retinoic Acid Exposure in Larval Summer Flounder, Paralichthys dentatus
Authors: Martinez Gabriela M. , Baron Michael P. , Bolker Jessica A.
Published: August 2007

Supplementation of larval diets with vitamin A (VA) is routinely and successfully used to stimulate pigmentation development in hatchery‐reared flatfishes. However, excess dietary VA can lead to high levels of its metabolite retinoic acid (RA) and has been associated with the occurrence of skeletal deformities, presumably via RA toxicity. We reared summer flounder larvae, Paralichthys dentatus, in water containing 0‐ to 20‐nM RA to assess its effects on postmetamorphic pigmentation and on skeletal development. RA exposure disrupted pigmentation development: treated tanks had a smaller percentage of normally pigmented fish than did controls, with increased numbers of both hypo‐ and hyperpigmented individuals. Exposure also affected the development of several skeletal features: RA treatment correlated with a significant increase in the severity of defects in jaws, fins, hypurals, and vertebrae compared with control groups.
Environmental Manipulation of Growth and Sexual Maturation in Yellow Perch, Perca flavescens
Authors: Shewmon Laura N. , Godwin John R. , Murashige Ryan S. , Daniels Harry V , Losordo Thomas M.
Published: August 2007

Yellow perch, Perca flavescens, exhibit sexually dimorphic growth detected as the fish enter puberty. The purpose of this study was to evaluate the differential influences of photoperiod and temperature on the sexual maturation and dimorphic growth pattern of yellow perch. Four combinations of constant (CP) or natural (NP) photoperiod with constant (CT) or natural (NT) temperature were evaluated (CPCT, CPNT, NPCT, NPNT). Following 6 months of growth, results indicate that (1) CT is the strongest promoter of overall growth regardless of photoperiod. Perch reared under CT were 26.4 ± 8.1 g heavier than perch reared under NT (P < 0.0001). (2) CP also promotes overall growth regardless of temperature. CP perch outgrew NP perch by 7.0 ± 8.1 g (P < 0.0872). (3) NP (decreasing) initiates maturation in yellow perch regardless of temperature. (4) NT is required for late maturational processes. While both NP groups initiated maturation, only NPNT females were able to recruit oocytes to a vitellogenic stage. Only NPNT males were able to sustain spermiation to the end of the study. (5) CPCT confer the best overall growth performance, fully inhibit maturation in both genders, and suppress a sexually dimorphic growth pattern up to 53 g average weight. These results indicate that using a CPCT regime during intensive fingerling production will produce a larger, more uniform fish population that could alleviate losses as a result of cannibalism. Perch that remained immature did not exhibit a dimorphic growth pattern.
Effect of Shrimp Stocking Density on Size‐fractionated Phytoplankton and Ecological Groups of Ciliated Protozoa within Zero‐water Exchange Shrimp Culture Systems
Authors: Decamp Olivier , Conquest Lytha , Cody Jeff , Forster Ian , Tacon Albert G. J.
Published: August 2007

Zero‐water exchange shrimp culture systems are being investigated to reduce water and pathogens input and effluent output. The relative abundance and diversity of ciliates have been used as indicators of water quality and ecosystem dynamics in natural systems; however, their occurrence and role in shrimp production systems have not been investigated. The objectives of this research were to describe the succession of the ciliate community in a shrimp grow out system, to investigate the impact of increasing shrimp stocking density on the characteristics of the ciliated protozoa community, and to correlate this with shrimp performance. A growth trial with Litopenaeus vannamei was conducted outdoors with zero‐water exchange and three stocking densities (50, 75 and 100 shrimp/m2). In all treatments, free‐swimming ciliates were dominant in the early weeks, while substrate‐associated ciliates appeared later. The 100 shrimp/m2 treatment exhibited a lower abundance of free‐swimming ciliates but higher abundance of hypotrichous ciliates in the second half of production and higher shrimp mortality and lower shrimp growth in the last 2 wk. These results provide a preliminary examination of the role of ciliates in shrimp culture systems and direction for future work in determining the role of protozoa as indicators of water quality.
Isolation of Sulfated Anticoagulant Compound from Fermented Red SeaweedGrateloupia filicina
Authors: Nikapitiya Chamilani , De Zoysa Mahanama , Jeon You‐Jin , Lee Jehee , Jee Youngheun
Published: August 2007

The red algaGrateloupia filicinawas fermented with 0.15 g/mL sucrose at 25 C, and anticoagulant activity was measured biweekly up to the 10th wk by activated partial thromboplastin time (APTT). A sulfated polysaccharide compound having anticoagulant activity was purified from the sixth wk of fermentation by fast protein liquid chromatography using diethylaminoethyl cellulose followed by a sepharose‐4B column. The concentration of the purified sulfated anticoagulant polysaccharide was 136.65 μg/mL, and the sulfate concentration of the purified compound was 26.33 μg/mL. The presence of just a single spot on agarose gel electrophoresis confirmed that the compound was purified, and polyacrylamide gel electrophoresis showed that the purified compound was of high molecular mass. The purified sulfated anticoagulant polysaccharide consisted of galactose, glucose, and mannose in an approximate molar ratio of 0.95 : 0.01 : 0.03. Both purified anticoagulant and commercial heparin showed >1000 sec APTT activity at 136.65 μg/mL. As the technique of fermentation is inexpensive, the purified anticoagulant compound could have significant potential in the medical and pharmaceutical industry.
Reevaluation of the Dietary Protein Requirements and Optimum Dietary Protein to Energy Ratios in Japanese Eel, Anguilla japonica
Authors: Okorie Okorie E. , Kim Young‐Chul , Lee Seunghyung , Bae Jun‐Young , Yoo Jin H. , Han Kyungmin , Bai Sungchul C. , Park Gun‐Jun , Choi Se‐Min
Published: August 2007

A 2 × 3 factorial design was used to reevaluate the dietary protein requirements and to determine the optimum dietary protein to energy (P/E) ratios in Japanese eel, Anguilla japonica, reared in the recirculating system. For each of two experiments, six experimental diets (45P16, 45P17, 45P19, 50P16, 50P17, and 50P19) were formulated and prepared to contain two protein levels (45 and 50%) and three energy levels (16, 17, and 19 kJ/g diet) at each protein level. In the first experiment, glass eel of initial weight 0.1 ± 0.02 g (mean ± SD) were used, while the second experiment was conducted with juvenile eel of initial weight 15.0 ± 3 g (mean ± SD). The first and second experimental periods were 6 and 16 wk for the glass and juvenile eel, respectively. At the end of the first experiment, there were no protein, energy, and their interaction effects. Also, there were no significant differences in weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) for glass Japanese eel fed all diets. Although there were no significant differences in growth parameters of glass eel fed all experimental diets, these parameters were higher for fish fed 50P16 than for fish fed the other diets. For the second experiment, there were significant protein effects on WG, SGR, and PER (P < 0.05). However, there were neither significant energy effects nor protein and energy interaction effects on WG, SGR, FE, and PER. Fish fed 45P19 had a higher WG, SGR, and PER than did fish fed 45P16, 50P16, and 50P19 (P < 0.05). However, there were no significant differences in growth parameters among fish fed 45P16, 45P17, 50P16, 50P17, and 50P19 and among those fed 45P17, 45P19, and 50P17. These results may indicate that the optimum dietary protein requirement and the P/E ratio could be 44.3% and 24.1 mg protein/kJ (45P19), respectively, in juvenile Japanese eel, based on WG, SGR, and PER.
Effect of Restricted Feeding Regimes on Compensatory Growth and Body Composition of Red Sea Bream, Pagrus major
Authors: Oh Sung‐Yong , Noh Choong Hwan , Cho Sung Hwoan
Published: August 2007

Compensatory growth of red sea bream, Pagrus major, during feed deprivation and after refeeding was investigated. Groups of three fish each were allocated into 28 cages. Fish were fed by a commercial feed to satiation twice a day. Four feeding groups of fish were prepared: one group with continuous feeding (C) for 9 wk and three other groups with feed deprivation for 1 wk (F1) in Week 3, 2 wk (F2) from Week 2 to Week 3, and 3 wk (F3) from Week 1 to Week 3, respectively. All fish in the feed deprivation treatments resumed feeding in Week 4. The full compensatory growth was achieved in F1 and F2 fish after refeeding for the first 3 wk but in F3 fish after refeeding for the second 3 wk. Specific growth rate and feed conversion efficiency in all fish experiencing fasting were higher than those of control fish after first 3 wk of refeeding. At the end of feed deprivation in Week 3, crude protein, crude lipid, and energy content of all fish experiencing fasting were lower than those of the control fish. These results indicated that red sea bream experienced 1‐, 2‐, and 3‐wk fasting could achieve full compensatory growth in the 9‐wk feeding trial.
Pseudomonas aeruginosa PAO1 virulence factors and poplar tree response in the rhizosphere
Authors: Attila Can , Ueda Akihiro , Cirillo Suat L. G. , Cirillo Jeffrey D. , Chen Wilfred , Wood Thomas K.
Published: August 2007

Whole‐transcriptome analysis was used here for the first time in the rhizosphere to discern the genes involved in the pathogenic response of Pseudomonas aeruginosa PAO1 as well as to discern the response of the poplar tree. Differential gene expression shows that 185 genes of the bacterium and 753 genes of the poplar tree were induced in the rhizosphere. Using the P. aeruginosa transcriptome analysis, isogenic knockout mutants, and two novel plant assays (poplar and barley), seven novel PAO1 virulence genes were identified (PA1385, PA2146, PA2462, PA2463, PA2663, PA4150 and PA4295). The uncharacterized putative haemolysin repressor, PA2463, upon inactivation, resulted in greater poplar virulence and elevated haemolysis while this mutant remained competitive in the rhizosphere. In addition, disruption of the haemolysin gene itself (PA2462) reduced the haemolytic activity of P. aeruginosa, caused less cytotoxicity and reduced barley virulence, as expected. Inactivating PA1385, a putative glycosyl transferase, reduced both poplar and barley virulence. Furthermore, disrupting PA2663, a putative membrane protein, reduced biofilm formation by 20‐fold. Inactivation of PA3476 (rhlI) increased virulence with barley as well as haemolytic activity and cytotoxicity, so quorum sensing is important in plant pathogenesis. Hence, this strategy is capable of elucidating virulence genes for an important pathogen.
Rhizoremediation of lindane by root‐colonizing Sphingomonas
Authors: Böltner Dietmar , Godoy Patricia , Muñoz‐Rojas Jesús , Duque Estrella , Moreno‐Morillas Silvia , Sánchez Lourdes , Ramos Juan Luis
Published: August 2007

We used a two‐step enrichment approach to isolate root‐colonizing hexachlorocyclohexane (HCH)‐degrading microorganisms. The first step consists of the use of classical liquid enrichment to isolate γ‐HCH degraders. The γ‐HCH‐degrading microbes were attached in mass to corn seeds sown in soil with γ‐HCH, and after plant development we rescued bacteria growing on root tips. Bacteria were then subjected to a second enrichment round in which growth on liquid medium with γ‐HCH and inoculation of corn seeds were repeated. We then isolated bacteria on M9 minimal medium with γ‐HCH from root tips. We were able to isolate four Sphingomonas strains, all of which degraded α‐, β‐, γ‐ and δ‐HCH. Two of the strains were particularly good colonizers of corn roots, reaching high cell density in vegetated soil and partly removing γ‐HCH. In contrast, these bacteria performed poorly in unplanted soils. This study supports the hypothesis that the removal of persistent toxic chemicals can be accelerated by combinations of plants and bacteria, a process generally known as rhizoremediation.
Riparian Ecosystem Management Model: Sensitivity to Soil, Vegetation, and Weather Input Parameters1
Authors: Kim Ik‐Jae , Hutchinson Stacy L. , Hutchinson J.M. Shawn , Young C. Bryan
Published: August 2007

Abstract:  The Riparian Ecosystem Management Model (REMM) was developed by the U.S. Department of Agriculture‐Agriculture Research Service (USDA‐ARS) and its cooperators to design and evaluate the efficiency of riparian buffer ecosystems for nonpoint source pollution reduction. REMM requires numerous inputs to simulate water movement, sediment transport, and nutrient cycling in the buffer system. In order to identify critical model inputs and their uncertainties, a univariate sensitivity analysis was conducted for nine REMM output variables. The magnitude of each input parameter was changed from −50% to +50% from the baseline data in 12 intervals or, in some cases, the complete range of an input was tested. Baseline model inputs for the sensitivity analysis were taken from Gibbs Farm, Georgia, where REMM was tested using a 5‐year field dataset. Results of the sensitivity analysis indicate that REMM responses were most sensitive to weather inputs, with minimum daily temperature having the greatest impact on the nitrogen‐related outputs. For example, the 100% change (−50% to +50%) in minimum daily temperature input values yielded a 164.4% change in total nitrogen (N), a 109.3% change in total nitrate (NO3), and a 127.1% change in denitrification. REMM was most sensitive to precipitation with regard to total flow leaving the riparian vegetative buffer zone (199.8%) and sediment yield (138.2%). Deep seepage (12.2%), volumetric water content (24.8%), and pore size index (6.5%) in the buffer soil profile were the most influential inputs for the output water movement. Sediment yield was most sensitive to Manning’s coefficient (46.6%), bare soil percent (40.7%), and soil permeability (6.1%). For vegetation, specific leaf area, growing degree day coefficients, and maximum root depth influenced the nitrogen related outputs. Overall results suggest that because of the high sensitivity to weather parameters, on‐site weather data is needed for model calibration and validation. The model’s relatively low sensitivity to vegetation parameters also appears to support the use of regional vegetation datasets that would simplify model implementation without compromising results.
Measuring the ventilatory response to hypoxia
Authors: Duffin James
Published: August 2007

After defining the current approach to measuring the hypoxic ventilatory response this paper explains why this method is not appropriate for comparisons between individuals or conditions, and does not adequately measure the parameters of the peripheral chemoreflex. A measurement regime is therefore proposed that incorporates three procedures. The first procedure measures the peripheral chemoreflex responsiveness to both hypoxia and CO2 in terms of hypoxia's effects on the sensitivity and ventilatory recruitment threshold of the peripheral chemoreflex response to CO2. The second and third procedures employ current methods for measuring the isocapnic and poikilocapnic ventilatory responses to hypoxia, respectively, over a period of 20 min. The isocapnic measure is used to determine the time course characteristics of hypoxic ventilatory decline and the poikilocapnic measure shows the ventilatory response to a hypoxic environment. A measurement regime incorporating these three procedures will permit a detailed assessment of the peripheral chemoreflex response to hypoxia that allows comparisons to be made between individuals and different physiological and environmental conditions.
Temperature enhances exocytosis efficiency at the mouse inner hair cell ribbon synapse
Authors: Nouvian Régis
Published: August 2007

Hearing relies on fast and sustained neurotransmitter release from inner hair cells (IHCs) onto the afferent auditory nerve fibres. The temperature dependence of Ca2+ current and transmitter release at the IHCs ribbon synapse has not been investigated thus far. To assess the influence of temperature on calcium‐triggered exocytosis, patch‐clamp recordings of voltage‐gated L‐type Ca2+ influx and exocytic membrane capacitance changes were performed at room (25°C) and physiological (35–37°C) temperatures. An increase in temperature within this range increased the L‐type Ca2+ current amplitude of IHCs (Q10= 1.3) and accelerates the activation kinetics. Fast exocytosis, probed by 20 ms depolarization, was enhanced at physiological temperature with a Q10 of 2.1. The amplitude of fast release was elevated disproportionately to the increase in Ca2+ influx. In contrast, the rate of sustained exocytosis (exocytic rate between 20 and 100 ms of depolarization) did not show a significant increase at physiological temperature. Altogether, these data indicate that the efficiency of fast exocytosis is higher at physiological temperature than at room temperature and suggest that the number of readily releasable vesicles available at the active zone is higher at physiological temperature.
Beneficial effects of L‐arginine–nitric oxide‐producing pathway in rats treated with alloxan
Authors: Vasilijević Ana , Buzadžić Biljana , Korać Aleksandra , Petrović Vesna , Janković Aleksandra , Korać Bato
Published: August 2007

In an attempt to elucidate molecular mechanisms and factors involved in β cell regeneration, we evaluated a possible role of thel‐arginine–nitric oxide (NO)‐producing pathway in alloxan‐induced diabetes mellitus. Diabetes was induced in male Mill Hill rats with a single alloxan dose (120 mg kg−1). Both non‐diabetic and diabetic groups were additionally separated into three subgroups: (i) receivingl‐arginine · HCl (2.25%), (ii) receivingl‐NAME · HCl (0.01%) for 12 days as drinking liquids, and (iii) control. Treatment of diabetic animals started after diabetes induction (glucose level ≥ 12 mmol l−1). We found that disturbed glucose homeostasis, i.e. blood insulin and glucose levels in diabetic rats was restored afterl‐arginine treatment. Immunohistochemical findings revealed thatl‐arginine had a favourable effect on β cell neogenesis, i.e. it increased the area of insulin‐immunopositive cells. Moreover, confocal microscopy showed colocalization of insulin and pancreas duodenum homeobox‐1 (PDX‐1) in both endocrine and exocrine pancreas. This increase in insulin‐expressing cells was accompanied by increased cell proliferation (observed by proliferating cell nuclear antigen‐PCNA immunopositivity) which occurred in a regulated manner since it was associated with increased apoptosis (detected by the TUNEL method). Furthermore,l‐arginine enhanced both nuclear factor‐kB (NF‐kB) and neuronal nitric oxide synthase (nNOS) immunopositivities. The effect ofl‐arginine on antioxidative defence was observed especially in restoring to control level the diabetes‐induced increase in glutathione peroxidase activity. In contrast tol‐arginine, diabetic pancreas was not affected byl‐NAME supplementation. In conclusion, the results suggest beneficiall‐arginine effects on alloxan‐induced diabetes resulting from the stimulation of β cell neogenesis, including complex mechanisms of transcriptional and redox regulation.
Effects of a common human gene variant of extracellular superoxide dismutase on endothelial function after endotoxin in mice
Authors: Lund Donald D. , Chu Yi , Brooks Robert M. , Faraci Frank M. , Heistad Donald D.
Published: August 2007

A common gene variant in the heparin‐binding domain (HBD) of extracellular superoxide dismutase (ECSOD) may predispose human carriers to ischaemic heart disease. We have demonstrated that the HBD of ECSOD is important for ECSOD to restore vascular dysfunction produced by endotoxin. The purpose of this study was to determine whether the gene variant in the HBD of ECSOD (ECSODR213G) protects against endothelial dysfunction in a model of inflammation. We constructed a recombinant adenovirus that expresses ECSODR213G. Adenoviral vectors expressing ECSOD, ECSODR213G or β‐galactosidase (LacZ, a control) were injected i.v. in mice. After 3 days, at which time the plasma SOD activity is maximal, vehicle or endotoxin (lipopolysaccharide or LPS, 40 mg kg−1) was injected i.p. Vasomotor function of aorta in vitro was examined 1 day later. Maximal relaxation to sodium nitroprusside was similar in aorta from normal and LPS‐treated mice. Maximal relaxation to acetylcholine (10−5) was impaired after LPS and LacZ (63 ± 3%, mean ±s.e.m.) compared to normal vessels (83 ± 3%) (P < 0.05). Gene transfer of ECSOD improved (P < 0.05) relaxation in response to acetylcholine (76 ± 5%) after LPS, whereas gene transfer of ECSODR213G had no effect (65 ± 4%). Superoxide was increased in aorta (measured using lucigenin and hydroethidine) after LPS, and levels of superoxide were significantly reduced following ECSOD but not ECSODR213G. Thus, ECSOD reduces superoxide and improves relaxation to acetylcholine in the aorta after LPS, while the ECSOD variant R213G had minimal effect. These findings suggest that, in contrast to ECSOD, the common human gene variant of ECSOD fails to protect against endothelial dysfunction produced by an inflammatory stimulus.
Morphology of inhibitory and excitatory interneurons in superficial laminae of the rat dorsal horn
Authors: Maxwell David J. , Belle Mino D. , Cheunsuang Ornsiri , Stewart Anika , Morris Richard
Published: August 2007

If we are to stand any chance of understanding the circuitry of the superficial dorsal horn, it is imperative that we can identify which classes of interneuron are excitatory and which are inhibitory. Our aim was to test the hypothesis that there is a correlation between the morphology of an interneuron and its postsynaptic action. We used in vitro slice preparations of the rat spinal cord to characterize and label interneurons in laminae I–III with Neurobiotin. Labelled cells (n= 19) were reconstructed in 3D with Neurolucida and classified according to the scheme proposed by Grudt & Perl (2002). We determined if cells were inhibitory or excitatory by reacting their axon terminals with antibodies to reveal glutamate decrboxylase (for GABAergic cells) or the vesicular glutamate transporter 2 (for glutamatergic cells). All five islet cells retrieved were inhibitory. Of the six vertical (stalked) cells analysed, four were excitatory and, surprisingly, two were inhibitory. It was noted that these inhibitory cells had axonal projections confined to lamina II whereas excitatory vertical cells projected to lamina I and II. Of the remaining neurons, three were radial cells (2 inhibitory, 1 excitatory), two were antennae cells (1 inhibitory, 1 excitatory), one was an inhibitory central cell and the remaining two were unclassifiable excitatory cells. Our hypothesis appears to be correct only for islet cells. Other classes of cells have mixed actions, and in the case of vertical cells, the axonal projection appears to be a more important determinant of postsynaptic action.
Endurance exercise performance in Masters athletes: age‐associated changes and underlying physiological mechanisms
Authors: Tanaka Hirofumi , Seals Douglas R.
Published: August 2007

Older (‘Masters’) athletes strive to maintain or even improve upon the performance they achieved at younger ages, but declines in athletic performance are inevitable with ageing. In this review, we describe changes in peak endurance exercise performance with advancing age as well as physiological factors responsible for those changes. Peak endurance performance is maintained until ∼35 years of age, followed by modest decreases until 50–60 years of age, with progressively steeper declines thereafter. Among the three main physiological determinants of endurance exercise performance (i.e. maximal oxygen consumption , lactate threshold and exercise economy), a progressive reduction in appears to be the primary mechanism associated with declines in endurance performance with age. A reduction in lactate threshold, i.e. the exercise intensity at which blood lactate concentration increases significantly above baseline, also contributes to the reduction in endurance performance with ageing, although this may be secondary to decreases in . In contrast, exercise economy (i.e. metabolic cost of sustained submaximal exercise) does not change with age in endurance‐trained adults. Decreases in maximal stroke volume, heart rate and arterio‐venous O2 difference all appear to contribute to the age‐related reductions in in endurance‐trained athletes. Declines in endurance exercise performance and its physiological determinants with ageing appear to be mediated in large part by a reduction in the intensity (velocity) and volume of the exercise that can be performed during training sessions. Given their impressive peak performance capability and physiological function capacity, Masters athletes remain a fascinating model of ‘exceptionally successful ageing’ and therefore are highly deserving of our continued scientific attention as physiologists.
Intrauterine growth restriction improves cerebral O2 utilization during hypercapnic hypoxia in newborn piglets
Authors: Bauer Reinhard , Walter Bernd , Brandl Ulrich
Published: August 2007

Data are scant regarding the capacity of cerebrovascular regulation during asphyxia for prevention of brain oxygen deficit in intrauterine growth‐restricted (IUGR) newborns. We tested the hypothesis that IUGR improves the ability of neonates to withstand critical periods of severe asphyxia by optimizing brain oxygen supply. Studies were conducted to examine the effects of IUGR on cerebral blood flow (CBF) regulation and oxygen consumption (cerebral metabolic rate for oxygen, CMRO2) at different stages of asphyxia (hypercapnic hypoxaemia) in comparison to pure hypoxia (normocapnic hypoxaemia). We used 1‐day‐old anaesthetized and ventilated piglets. Animals were divided into normal weight (NW) piglets (n= 47; aged 11–26 h, body weight 1481 ± 121 g) and IUGR piglets (n= 48; aged 13–28 h, body weight 806 ± 42 g) according to their birth weight. Different stages of hypoxaemia were induced for 1 h by appropriate lowering of the inspired fraction of oxygen (moderate hypoxia: = 31–34 mmHg; severe hypoxia: = 20–22 mmHg). Fourteen NW and 16 IUGR piglets received additionally 9% CO2 in the breathing gas, so that a of 74–80 mmHg resulted (hypoxia/hypercapnia groups). Eight NW and nine IUGR animals served as untreated controls. Furthermore, affinity of haemoglobin for oxygen was measured under hypoxic and asphyxic conditions. During asphyxia cerebral oxygen extraction was markedly increased in IUGR animals (P < 0.05). This resulted in a significantly diminished CMRO2‐related increase of CBF at gradually reduced arterial oxygen content (P < 0.05). Therefore, an enhanced effectivity in oxygen availability appeared in newborn IUGR piglets under graded asphyxia by improved cerebral oxygen utilization (P < 0.05). This was not supported by related O2 affinity of haemoglobin. Thus, IUGR newborns are more capable to ensure brain O2 demand during asphyxia (hypercapnic hypoxia) than NW neonates.
Cysteine Redox Sensor in PKGIa Enables Oxidant-Induced Activation
Authors: Burgoyne Joseph R. , Madhani Melanie , Cuello Friederike , Charles Rebecca L. , Brennan Jonathan P. , Schröder Ewald , Browning Darren D. , Eaton Philip
Published: August 2007

Changes in the concentration of oxidants in cells can regulate biochemical signaling mechanisms that control cell function. We have found that guanosine 3′,5′-monophosphate (cGMP)–dependent protein kinase (PKG) functions directly as a redox sensor. The Iα isoform, PKGIα, formed an interprotein disulfide linking its two subunits in cells exposed to exogenous hydrogen peroxide. This oxidation directly activated the kinase in vitro, and in rat cells and tissues. The affinity of the kinase for substrates it phosphorylates was enhanced by disulfide formation. This oxidation-induced activation represents an alternate mechanism for regulation along with the classical activation involving nitric oxide and cGMP. This mechanism underlies cGMP-independent vasorelaxation in response to oxidants in the cardiovascular system and provides a molecular explantion for how hydrogen peroxide can operate as an endothelium-derived hyperpolarizing factor.
A comparison of cleat types during two football-specific tasks on FieldTurf
Authors: Queen R M , Charnock B L , Garrett W E , Hardaker W M , Sims E L , Moorman C T
Published: August 2007

Objective:

To examine the effect of different cleat plate configurations on plantar pressure during two tasks.

Design:

Thirty-six athletes ran an agility course 5 times while wearing 4 different types of Nike Vitoria cleats: (1) bladed, (2) elliptical firm ground, (3) hard ground and (4) turf. Plantar pressure data were recorded during a side cut and a cross cut using Pedar-X insoles.

Setting:

Controlled laboratory study

Participants:

No history of lower extremity injury in the past 6 months, no previous foot or ankle surgery, not currently wearing foot orthotics and play a cleated sport at least twice a week.

Main outcome measurements:

Total foot contact time, contact area, maximum force, peak pressure and the force-time integral (FTI) in the medial, middle and lateral regions of the forefoot were collected. A 1×4 ANOVA (α = 0.05) was performed on each dependent variable. A Bonferroni adjustment was conducted (α = 0.008).

Results:

In the cross cut task, statistical differences between cleats were observed in three variables: total foot peak pressure, lateral forefoot FTI, and lateral forefoot normalised maximum force. In the side cut task, statistical differences between cleats were observed in 4 variables: total foot peak pressure, the medial and middle forefoot FTI, and the medial and middle forefoot normalised maximum force.

Conclusions:

Significant differences in forefoot loading patterns existed between cleat types. Based on the results of this study, it might be beneficial to increase the forefoot cushioning in cleats in an attempt to decrease loading in these regions of the foot.
Chronic dynamic exercise increases apolipoprotein A-I expression in rabbit renal cortex as determined by proteomic technology: Figure 1
Authors: Moraes R de , Valente R H , León I R , Trugilho M R O , Nóbrega A C L , Perales J , Tibiriçá E
Published: August 2007

Objective:

We have shown previously that exercise training enhances endothelium-dependent and endothelium-independent vascular relaxation in rabbit kidney. This study aimed to investigate protein expression changes in the rabbit renal cortex induced by chronic dynamic exercise.

Design:

Kidneys were obtained from New Zealand rabbits either confined to pens (n = 8) or trained on a treadmill (0% grade) for 5 days/week at a speed of 18 m/min for 60-min periods over 12 weeks (n = 8). Expression of proteins in the renal cortex was determined by colloidal Coomassie blue staining after two-dimensional polyacrylamide gel electrophoresis. Differential protein spots were excised and digested with trypsin, and peptides were sequenced by electrospray ionization-ion trap mass spectrometry.

Results:

Two pairs of matching differentially stained spots displayed an approximate threefold increase in trained compared with sedentary animals. These four spots presented a molecular mass of 23 kDa but different pI values. Mass spectrometric analyses revealed the pairs of matching spots as being rabbit apolipoprotein A-I.

Conclusion:

Chronic dynamic exercise increases apolipoprotein A-I expression in the rabbit renal cortex. This fact could be involved in the alterations observed in the renal circulation after exercise training.
Efficacy of personal symptom and family history questionnaires when screening for inherited cardiac pathologies: the role of electrocardiography
Authors: Wilson M G , Basavarajaiah S , Whyte G P , Cox S , Loosemore M , Sharma S
Published: August 2007

Aims:

This study sought to confirm the efficacy of using resting 12-lead ECG alongside personal symptom and family history questionnaires and physical examination when screening for diseases with the potential to cause sudden cardiac death in the young.

Methods and results:

1074 national and international junior athletes (mean age 15.8 (SD 0.7) years, range 10 to 27) and 1646 physically active schoolchildren (16.1 (SD 2.1) years, range 14 to 20) were screened using personal and family history questionnaires, physical examination and resting 12-lead ECG. Nine participants with a positive diagnosis of a disease associated with sudden cardiac death were identified. None of the participants diagnosed with a disease associated with sudden cardiac death were symptomatic or had a family history of note.

Conclusion

: Family history and personal symptom questionnaires alone are inadequate to identify people with diseases associated with sudden cardiac death. Use of the 12-lead ECG is essential when screening for cardiac pathology in the young.
Feasibility of a walking workstation to increase daily walking
Authors: Thompson W G , Foster R C , Eide D S , Levine J A
Published: August 2007

Objective:

The number of calories expended in the workplace has declined significantly in the past 75 years. A walking workstation that allows workers to walk while they work has the potential to increase caloric expenditure. We evaluated whether employees can and will use walking workstations while performing their jobs.

Methods and procedures:

We studied nurses, clinical assistants, secretaries and appointment secretaries using the StepWatch Activity Monitor System (which accurately measures steps taken at slow speeds) while performing their job functions in their usual fashion and while using the walking workstation.

Results:

Subjects increased the number of steps taken during the workday by 2000 steps per day (p<0.05). This was equivalent to an increase in caloric expenditure of 100 kcal/day. Subjects reported that they enjoyed using the workstation, that it could be used in the actual work arena and that, if available, they would use it.

Discussion:

Walking workstations have the potential for promoting physical activity and facilitating weight loss. Several subjects in this study expended more than 200 extra calories daily using such a system. Further trials are indicated.
Re-thinking the embryo lethal system within the Pinaceae
Authors: Williams Claire G.
Published: August 2007

Outcrossing, wind-pollinated members of the Pinaceae have high self-pollination rates yet produce few selfed seedlings. How are selfs selectively eliminated? Barriers to selfing have long been considered to be (i) avoidance of self-pollen capture, (ii) competition via simple polyembryony, and (iii) lower viability of selfed embryos. Here, reviews — and some revisions — are offered in addition to future research needs. First, avoiding self-pollen capture is largely ineffectual. Second, simple polyembrony is also a weak or nonexistent barrier against selfed embryos. Third, selfed embryos die at all stages, but a stage-specific death peak occurs during early embryogeny in some taxa and this death peak, if prevalent across a wider range of taxa, deserves a closer look. The death peak does not preclude the prevailing genetic model for embryo viability loci, but could indicate that other genetic mechanisms are operative. Molecular dissection shows that zygotic lethals are distributed across different chromosomal segments. To date, these are mostly semi-lethal rather than lethal, and they range from partially dominant to overdominant. A literature survey suggests that only 5 of the 10 genera within the Pinaceae ( Abies , Larix , Picea , Pinus , and Pseudotsuga ) have been well characterized with respect to selfing. Extreme inbreeding depression during embryo development may not be a shared feature among conifers as a group. A critical research question is whether dual death patterns are present in other genera, and if they are, alternative genetic models to account for the death peak. Addressing these questions has broad relevance to conservation, domestication, and management of closed populations, not just conifers or gymnosperms.
Genetic variation in twoChamaecristaspecies (Leguminosae), one endangered and narrowly distributed and another widespread in the Serra do Espinhaço, Brazil
Authors: Silva Reinaldo Moreira da , Fernandes G. Wilson , Lovato Maria Bernadete
Published: August 2007

The Serra do Espinhaço in Brazil is under continuous and increasing levels of human disturbance. It has a large number of endemic plant species such as Chamaecrista semaphora (Irwin and Barneby), an endangered species with extremely narrow range. We studied the genetic diversity of C. semaphora and compared it with Chamaecrista mucronata (Spreng.) Irwin and Barneby, a widespread congeneric species distributed over the entire Serra do Espinhaço, in an attempt to provide information for conservation strategies. Two populations of C. mucronata and the only two known populations of C. semaphora from Serra do Cipó were screened for variability using random amplified polymorphic DNA (RAPD) markers. Populations of C. semaphora exhibited a lower percentage of polymorphic markers (16.9%) and Shannon’s Diversity Index (H′pop= 0.124) than C. mucronata populations (43.3% and H′pop= 0.299). Most of the genetic variability of both species studied was distributed within populations; C. semaphora populations (ΦST= 0.198) were less divergent than C. mucronata populations (ΦST= 0.378). The risk of extinction for C. semaphora is large owing to its low level of genetic diversity compared with its widespread congener and because of increasing habitat destruction. Both populations of C. semaphora urgently need protection to maximize the genetic diversity of this species and diminish further substantial loss within the populations.
Bound-state variational wave equation for fermion systems in quantum electrodynamics
Authors: Terekidi A G , Darewych J W , Horbatsch M
Published: August 2007

We present a formulation of the Hamiltonian variational method for quantum electrodynamics (QED) that enables the derivation of a relativistic few-fermion wave equation that can account, at least in principle, for interactions to any order of the coupling constant. We derive a relativistic two-fermion wave equation using this approach. The interaction kernel of the equation is shown to be the generalized invariant [Formula: see text] matrix including all orders of Feynman diagrams. The result is obtained rigorously from the underlying quantum field theory (QFT) for an arbitrary mass ratio of the two fermions. Our approach is based on three key points: a reformulation of QED, the variational method, and adiabatic hypothesis. As an application, we calculate the one-loop contribution of radiative corrections to the two-fermion binding energy for singlet states with arbitrary principal quantum number n, and [Formula: see text] = J = 0. Our calculations are carried out in the explicitly covariant Feynman gauge.PACS Nos.: 12.20.–m
PARABOLA SEPARATION QUERIES AND THEIR APPLICATION TO STONE THROWING
Authors: CHEONG OTFRIED , EVERETT HAZEL , KIM HYO-SIL , LAZARD SYLVAIN , SCHOTT RENÉ
Published: August 2007

Given two sets A and B of m non-crossing line segments in the plane, we show how to compute in O(m log m) time a data structure that uses O(m) storage and supports the following query in O( log m) time: Given a parabola γ : y = ax2 + bx + c, does γ separate A and B? This structure can be used to build a data structure that stores a simple polygon and allows ray-shooting queries along parabolic trajectories with vertical main axis. For a polygon of complexity n, we can answer such "stone-throwing" queries in O( log 2 n) time, using O(n log n) storage and O(n log 2 n) preprocessing time. This matches the best known bound for circular ray shooting in simple polygons.
CROSS HEDGING WITHIN A LOG MEAN REVERTING MODEL
Authors: NJOH SAMUEL
Published: August 2007

We hedge options on electricity spot prices by cross hedging, i.e., by using another financial asset. We calculate hedging strategies by quadratic minimization and local risk minimization. In our model of energy markets, we have done a deep study of no arbitrage and of the existence of martingale measures with square integrable density. Then we have established tools for efficient hedges. Nevertheless, we have clearly proved possible limitations of the expiry of options with quadratic criteria.
BARRIER PROBABILITIES AND MAXIMUM SEVERITY OF RUIN FOR A RENEWAL RISK MODEL
Authors: THAMPI K. K. , JACOB M. J. , RAJU N.
Published: August 2007

In this paper, we consider a renewal risk model with dividend barrier, in which the claim inter-occurrence times are generalized exponential. We obtain explicit expression for the probability of absorption by an upper barrier b, before ruin occurs when the claim amount distribution is either mixed exponential or Gamma. We apply these results to obtain the distribution of the maximum deficit at the time of ruin. We also consider the numerical evaluation of the barrier probability, B(u, b), and the probability of maximum severity in some specific cases.
ON INCIDENCE MODULO IDEAL RINGS
Authors: DOKUCHAEV M. A. , KIRICHENKO V. V. , NOVIKOV B. V. , PETRAVCHUK A. P.
Published: August 2007

For a given associative ring B, a two-sided ideal J ⊂ B and a finite partially ordered set P, we study the ring A = I(P, B, J) of incidence modulo J matrices determined by P. The properties of A involving its radical and quiver are investigated, and the interaction of A with serial rings is explored. The category of A-modules is studied if P is linearly ordered. Applications to the general linear group over some local rings are given.
PATH HYPERGEOMETRIC FUNCTIONS
Authors: XU XIAOPING
Published: August 2007

Under a certain condition, we find the explicit formulas for the trace functions of certain intertwining operators among gl(n)-modules, introduced by Etingof in connection with the solutions of the Calogero–Sutherland model. If n = 2, the master function of the trace function is exactly the classical Gauss hypergeometric function. When n > 2, the master functions of the trace functions are a new family of multiple hypergeometric functions, whose differential property and Euler type integral representation are dominated by certain polynomials of integral paths connecting pairs of positive integers. Moreover, we also find the trace functions for sp(2n) explicitly and prove that they give rise to solutions of the Olshanesky–Perelomov model of type C. The master functions of the trace functions for sp(2n) are similar new multiple path hypergeometric functions. Analogous multiple path hypergeometric functions for orthogonal Lie algebras are defined and studied.
GENERALIZING A THEOREM OF HUPPERT AND MANZ
Authors: LEWIS MARK L.
Published: August 2007

Huppert and Manz proved that if G is a nonsolvable group where all the character degrees are square-free, then G ≅ A7 × S, where S is a solvable group with no degree divisible by 2, 3, 5, or 7. We weaken the hypothesis of Huppert and Manz's theorem to prove the following generalization. If G is a nonsolvable group and 4 divides no character degree of G, then G ≅ A7 × S, where S is a solvable group with no degree divisible by 2.
CLEAN, ALMOST CLEAN, POTENT COMMUTATIVE RINGS
Authors: VARADARAJAN K.
Published: August 2007

We give a complete characterization of the class of commutative rings R possessing the property that Spec(R) is weakly 0-dimensional. They turn out to be the same as strongly π-regular rings. We considerably strengthen the results of K. Samei [13] tying up cleanness of R with the zero dimensionality of Max(R) in the Zariski topology. In the class of rings C(X), W. Wm Mc Govern [6] has characterized potent rings as the ones with X admitting a clopen π-base. We prove the analogous result for any commutative ring in terms of the Zariski topology on Max(R). Mc Govern also introduced the concept of an almost clean ring and proved that C(X) is almost clean if and only if it is clean. We prove a similar result for all Gelfand rings R with J(R) = 0.
DEVELOPMENT OF MATHEMATICAL MODEL OF BLAST FURNACE SMELTING
Authors: DMITRIEV ANDREY N.
Published: August 2007

The solution of a problem of mathematical description of heat exchange, gas dynamics and the physicochemical phenomena taking place in blast furnace, and some of its application for the study of processes, and defining reduction of metals from multicomponent iron ores are considered.
A NOVEL INDEXING AND ACCESS MECHANISM USING AFFINITY HYBRID TREE FOR CONTENT-BASED IMAGE RETRIEVAL IN MULTIMEDIA DATABASES
Authors: CHATTERJEE KASTURI , CHEN SHU-CHING
Published: August 2007

An efficient access and indexing framework, called Affinity Hybrid Tree (AH-Tree), is proposed which combines feature and metric spaces in a novel way. The proposed framework helps to organize large image databases and support popular multimedia retrieval mechanisms like Content-Based Image Retrieval (CBIR). It is efficient in terms of computational overhead and fairly accurate in producing query results close to human perception. AH-Tree, by being able to introduce the high level semantic image relationship as it is in its index structure, solves the problem of translating the content-similarity measurement into feature level equivalence which is both painstaking and error-prone. Algorithms for similarity (range and k-nearest neighbor) queries are implemented and extensive experiments are performed which produces encouraging results with low I/O and distance computations and high precision of query results.