bluuebunny/crossref_metadata_2025 huggingface dataset:
An ultrastructural pachytene karyotype for Puccinia graminis f.sp. tritici
Authors: Boehm E. W. A. , Wenstrom J. C. , McLaughlin D. J. , Szabo L. J. , Roelfs A. P. , Bushnell W. R.
Published: October 2007

The karyotype for Puccinia graminis f.sp. tritici was determined from reconstructions of electron micrographs of serially sectioned pachytene nuclei. Epifluorescence microscopy was used to select DAPI-stained, pachytene nuclei in teliospore protoplasts from which walls were mechanically removed. Selection increased the probability that pachytene nuclei could be found in the absence of morphological markers. Six pachytene nuclei were reconstructed from four geographically disparate North American isolates. One nucleus was used to obtain a computer-enhanced, three-dimensional reconstruction that could be rendered as rotatable colorized stereo pairs. A karyotype of n = 18 was determined for all six nuclei. The 18 bivalents varied only slightly in size, each ranging from 3.0 to 8.8% of the total length of the genome. Total genomic lengths also proved highly comparable among isolates. Centromeres were not found, precluding use of the centromeric index as an aid in karyotyping. Only the nucleolus-associated bivalent could be cross-correlated among the six reconstructed nuclei. Heterogeneity in length among, but not within, isolates was observed for this bivalent, suggesting that chromosome length may be polymorphic in P. graminis f.sp. tritici, despite a constant total number of chromosomes. Key words: chromosomes, heterobasidiomycete, synaptonemal complex, Uredinales.
Phaeogalera and Galerina in arctic-subarctic Alaska (U.S.A.) and the Yukon Territory (Canada)
Authors: Horak E. , Miller Jr. O. K.
Published: October 2007

Eleven taxa of Galerina and Phaeogalera are described. Galerina leptocystis, Galerina subarctica, and Galerina praticola are reported from arctic North America for the first time. Phaeogalra stagnina is only found in very humid, wet meadow tundra associated with Drepanocladus or Calliergon. Galerina arctica is reported for the first time from Alaska and Canada. One species, Galerina pseudocerina, is found only in arctic alpine habitats in Canada and not in the arctic tundra. Two forms of Galerina pseudomycenopsis represent the most common taxon observed in Alaskan North Slope wet meadow tundra on peat or associated with Calliergon, Drepanocladus, and Sphagnum. Two species, Galerina clavata and Galerina hypnorum, are common cosmopolitan taxa, but only G. clavata is frequently encountered on the Alaskan North Slope. The association of the Galerina taxa with mosses is presented and discussed, as well as their occurrence in microhabitats in wet meadow tundra and among polygons in coastal tundra on the Alaskan North Slope. Key words: Galerina, Phaeogalera, Cortinariaceae, Alaska, Yukon Territory, bryophytes.
L'usage de l'article devant le binôme latin désignant les espèces du monde vivant
Authors: Richard Claude , Fortier Ginette , Boullard Bernard
Published: October 2007

In French, the use of the article with the Latin binomial identifying species is inconsistent. On the basis of grammatical rules and logic, the authors propose a standardized use of the article before the Latin binomial. Key words: nomenclature, article, Latin binomial, French language.
The correlation between the induction kinetics of the photoacoustic signal and chlorophyll fluorescence in barley leaves is governed by changes in the redox state of the photosystem II acceptor side. A study under atmospheric and high CO2concentrations
Authors: Bukhov Nikolai G. , Boucher Nathalie , Carpentier Robert
Published: October 2007

The induction kinetics of chlorophyll fluorescence were measured in dark-adapted barley leaves simultaneously with O2evolution and thermal dissipation using photoacoustic spectroscopy. Significant correlations were revealed between these parameters at low and high (about 5%) CO2concentrations and different irradiances. In general, four phases were resolved in the induction curves of chlorophyll fluorescence or PA signals modulated at 35 Hz (O2-dependent component) or 400 Hz (thermal dissipation). During the first 10–15 s after onset of actinic light, a high level of reduction of the primary quinone acceptor of photosystem II (QA), a low magnitude of the O2-dependent photoacoustic signal, and a high level of heat production measured as the photoacoustic signal at 400 Hz were maintained. Further illumination led to a partial QA−reoxidation, an increased rate of O2evolution, and a decline in heat production owing to an increased energy storage at the level of the plastoquinone pool. At low CO2concentration, the steady-state level of all the above parameters was attained at the end of the first minute of illumination and remained unmodified after prolonged leaf irradiation. In contrast, the development of an additional slow peak followed by its dissipation was found for all parameters examined under high CO2concentration and strong irradiance. The position of the slow peak in the kinetics of the O2-dependent photoacoustic signal preceded the corresponding peak of chlorophyll fluorescence measured under actinic light but coincided with the position of the peak in the kinetics of photochemical quenching. The position of the slow peak in the kinetics of thermal dissipation strictly corresponded to the one of chlorophyll fluorescence. A linear correlation was found between the magnitudes of the O2-dependent component of the photoacoustic signal and the extent of photochemical quenching. The results indicate that correlations in the kinetics and magnitudes of chlorophyll fluorescence, O2evolution, and thermal dissipation are due at least in part to the dependence of the above parameters on the redox state of the acceptor side of photosystem II. Key words: photosynthesis, chlorophyll fluorescence, thermal dissipation, CO2, O2evolution, plastoquinone, photoacoustic.
Sex differences in floral nectar production bySilene latifolia(Caryophyllaceae), with reference to susceptibility to a pollinator-borne fungal disease
Authors: Shykoff Jacqui A.
Published: October 2007

Nectar production and concentration were measured on male and female plants of six experimental lines of Silene latifolia (Caryophyllaceae) that differ in disease resistance. Differences between the sexes and among the lines were found for nectar production, concentration, and total sugar production during the first 24 h of anthesis. Females produced more nectar of lower concentration than did males, and males secreted more sugar than did females during the first day of anthesis. However, nectar traits of males and females resembled one another within a line, suggesting a genetic correlation between the sexes. Further, the additive genetic basis for this trait appears weak. In S. latifolia repeatabilities for nectar traits were low and differed between females and males, so the heritabilities must be extremely low. Groups of plant lines that are "susceptible" and "resistant" to the fungal pathogen Microbotryum violaceum did not differ in nectar parameters. Therefore resistance to this pollinator-borne disease does not appear to influence nectar production. Key words: Microbotryum (= Ustilago), plant – pathogen interactions, pollinator reward, anther-smut disease, dioecy, floral nectar.
Phylogenesis of pit-plug-associated features in the Rhodophyta: inferences from molecular systematic data
Authors: Saunders Gary W. , Bailey J. Craig
Published: October 2007

Small-subunit ribosomal RNA sequence data are presented for Rhodogorgon carriebowensis Norris et Bucher (Rhodogorgonales, Rhodophyta) and Galaxaura marginata (Ellis et Solander) Lamouroux (Nemaliales, Rhodophyta). Data for these species were included in a matrix consisting of small-subunit ribosomal RNA sequences for 70 taxonomically diverse red algal species. Distance, parsimony, and maximum-likelihood analyses of these data all strongly support (100% of bootstrap replicates for distance and parsimony) a close alliance between the Rhodogorgonales and Corallinales. Our alignment includes 19 species representing six florideophyte orders (Acrochaetiales, Batrachospermales, Corallinales, Nemaliales, Palmariales, Rhodogorgonales) in which pit plugs are characterized by two cap layers. Distance and parsimony analyses resolve a monophyletic lineage including all "two-cap-layer" species. Our parsimony-derived molecular phylogeny was used to test a published hypothesis of pit-plug evolution. Four aspects of Pueschel's hypothesis are consistent with the results of our molecular systematic study: (i) "naked" plugs represent the ancestral type, (ii) outer cap layers are homologous structures, (iii) domed outer caps are ancestral to plate-like outer caps, and (iv) cap membranes are a derived feature within the two-cap-layer lineage. Directions for future research are discussed. Key words: Acrochaetiales, Batrachospermales, Corallinales, molecular systematics, Nemaliales, Palmariales, phylogeny, pit plug, Rhodogorgonales, Rhodophyta.
Tapetum character states: analytical keys for tapetum types and activities
Authors: Pacini E.
Published: October 2007

The different types of tapetum found in the spermatophyta are described, along with associated characters. The characters (taken singly, pairwise, or in multiple combinations) are (i) tapetum types; (ii) cell walls, tapetum types, and loculus; (iii) tapetal cells individually, tapetum types, and loculus; (iv) number of pollen grains enveloped by tapetal cells and type of pollen dispersing unit; (v) cell types and tapetum types; (vi) number of nuclei per cell and tapetum type; (vii) cycles of hyperactivity; (viii) exine formation; (ix) orbicles; (x) peritapetal membrane; (xi) plastid differentiation; (xii) stage of pollen development in which tapetal cells degenerate and type of pollen coat; (xiii) storage vacuoles; (xiv) sporophytic proteins; and (xv) devices of tapetal origin responsible for compound pollen formation and pollination. Examples are given and an analytical key of structural and functional diversity is provided as a helpful approach to the study of the tapetum. Key words: tapetum types, activities, pollen dispersing units.
Variability in the highly virulent type ofLeptosphaeria maculanswithin and between oilseed rape fields
Authors: Mahuku George S. , Goodwin Paul H. , Hall Robert , Hsiang Tom
Published: October 2007

Pathogenicity and random amplified polymorphic DNA (RAPD) markers were used to assess genetic diversity among 93 highly virulent isolates of Leptosphaeria maculans (Desm.) Ces. & de Not. collected from two oilseed rape (Brassica napus L.) fields located 20 km apart in southern Ontario. Using three differential host cultivars of B. napus (Westar, Quinta, and Glacier), isolates were separated into three pathogenicity groups (PG). Eighty percent of the isolates were in PG4, virulent on all cultivars, and 11% were in PG3, virulent on two cultivars. The remaining 9% were tentatively placed into a new PG, PG5, because they showed intermediate virulence on the three cultivars. There was no relationship between RAPD pattern and either PG or isolate collection site. Cluster analysis of RAPD patterns, based on estimates of genetic distance, grouped isolates into two populations, corresponding to the field of collection. Analysis of molecular variance attributed 45.5% of the total variance to differences between populations and 54.5% to differences among isolates. Every isolate was genetically distinct, suggesting that the populations of the fungus were produced mostly by sexual reproduction. We conclude that inoculum in the two fields consisted principally of ascopores, derived almost equally from sources that were common to both fields and sources that were distinct for each field. Key words: highly virulent, Leptosphaerla maculans, random amplified polymorphic DNA (RAPD), genetic variation.
Effects of arbuscular mycorrhizae on leaf water potential, sugar content, and P content during drought and recovery of maize
Authors: Subramanian K. S. , Charest C. , Dwyer L. M. , Hamilton R. I.
Published: October 2007

The effect of colonization with the arbuscular mycorrhizal (AM) fungus (Glomus intraradices Schenck & Smith) in maize (Zea mays L.) under drought or nondrought conditions, on leaf water potential and sugar and phosphorus status was examined in a greenhouse study. Seeds of selection-cycles 0 (C0, drought sensitive) and 8 (C8, drought resistant) of the tropical maize cultivar Tuxpeño sequía were used for this experiment. Maize plants were exposed to 3 weeks of drought (45–65 days after sowing) followed by 3 weeks of recovery (66 – 86 days) at preflowering stage. Daily midday leaf water potential during drought and recovery periods and daily soil moisture content and weekly leaf relative water content during drought were measured. Sugar concentrations, phosphorus contents, and dry masses of roots and shoots were determined at the end of drought and recovery periods. Mycorrhizal plants of C0 and C8 maintained higher (less negative) leaf water potential during 3 weeks of drought. During recovery, AM plants took less time (C0, 7 days; C8, 4 days) than non-AM plants (C0, 15 days; C8, 8 days) to attain leaf water potential comparable with well-watered plants. The AM plants had higher phosphorus contents at the end of drought and recovery periods. Drought reduced the sugars in shoots by 66 and 50% in non-AM plants and by only 30 and 32% in AM plants of C0 and C8, respectively. Root and shoot masses were higher in AM than non-AM plants under well-watered and drought-stressed conditions. Overall results suggest that AM colonization helped the host plant to sustain moderate drought stress and recover rapidly when the irrigation was restored. Key words: corn, drought, endomycorrhizae, recovery, water relations.
13C nuclear magnetic resonance spectroscopy with cross-polarization and magic-angle spinning investigation of the proximate-analysis fractions used to assess litter quality in decomposition studies
Authors: Preston Caroline M. , (Tony) Trofymow J. A. , Niu Junning , Sayer Brian G.
Published: October 2007

Proximate analysis is often used in decomposition studies to characterize the organic components of foliar litter. The percent weight residue remaining after extraction by nonpolar and polar solvents and H3SO4 hydrolysis (Klason lignin, KL) is commonly used as a measure of litter quality and a modelling parameter. While KL is associated with resistance to decay, its nature is not well understood and it has long been suspected that it incorporates nonlignin components. We used solid-state 13C nuclear magnetic resonance (NMR) spectroscopy to characterize litter, extracted residue, and the KL fraction of five species. NMR shows that cutin and condensed tannin are both significant components of litter and its extraction residues, in addition to lignin and carbohydrate. Hydrolysis with H2SO4 removes carbohydrates and amino acids, leaving the KL fraction derived from cutin, tannin, and lignin. Tannin retention in KL was also demonstrated by a hydrolysis study of purified tannins and a brown-rot lignin, using both NMR and the proanthocyanidin assay for condensed tannins. Although the NMR results are qualitative at this stage, it is clear that KL has limited use as a parameter controlling litter decomposition, and that other biopolymers should not be ignored in conceptual models, chemical analysis, and experimental design. Key words: Klason lignin, 13C CPMAS NMR, proximate analysis, litter quality, decomposition, tannin.
SPACE–TIME IN LIGHT OF KÁROLYHÁZY UNCERTAINTY RELATION
Authors: MAZIASHVILI MICHAEL
Published: October 2007

General relativity and quantum mechanics provide a natural explanation for the existence of dark energy with its observed value and predict its dynamics. Dark energy proves to be necessary for the existence of space–time itself and determines the rate of its stability.
Array-Based DNA Diagnostics: Let the Revolution Begin
Authors: Beaudet Arthur L. , Belmont John W.
Published: October 2007

Advances in the fabrication of DNA microarrays as well as transformations in detection chemistries have vastly increased the throughput for genotyping, DNA sequencing, and array-based copy number analysis (ABCNA). Rapid changes in technology are not only affecting research but also revolutionizing DNA diagnostics. Here we focus on the application of high-throughput ABCNA and genotyping. Targeted and genome-wide ABCNA has led to the discovery of extensive DNA copy number variation in the population and the delineation of many previously unrecognized submicroscopic chromosomal aberrations (genomic disorders). High-throughput single-nucleotide polymorphism (SNP) genotyping is being widely applied in genome-wide association studies (GWASs) with recent successes in identification of common variants that confer risk for common adult diseases. Future applications of high-throughput genotyping and array-based DNA sequencing technology will undoubtedly involve research and diagnostic analyses of rare mutations and perhaps ultimately enable full individual genome sequencing.
A Current View of the Mammalian Aquaglyceroporins
Authors: Rojek Aleksandra , Praetorius Jeppe , Frøkiaer Jørgen , Nielsen Søren , Fenton Robert A.
Published: October 2007

The discovery of aquaporin water channels by Agre and coworkers answered a long-standing biophysical question of how the majority of water crosses biological membranes. The identification and study of aquaporins have provided insight, at the molecular level, into the fundamental physiology of water balance regulation and the pathophysiology of water balance disorders. In addition to the originally identified classical aquaporins, a second class of aquaporins has been identified. Aquaporins in this latter class, the so-called aquaglyceroporins, transport small uncharged molecules such as glycerol and urea as well as water. Aquaglyceroporins have a wide tissue distribution, and emerging data suggest that several of them may play previously unappreciated physiological or pathophysiological roles. Analyses of transgenic mice have revealed potential roles of aquaglyceroporins in skin elasticity, gastrointestinal function and metabolism, and metabolic diseases such as diabetes mellitus. This review comprehensively discusses the recent discoveries in the field of aquaglyceroporins, alongside a brief overview of the so-called unorthodox aquaporins.
Molecular Physiology of the WNK Kinases
Authors: Kahle Kristopher T. , Ring Aaron M. , Lifton Richard P.
Published: October 2007

Mutations in the serine-threonine kinases WNK1 and WNK4 cause a Mendelian disease featuring hypertension and hyperkalemia. In vitro and in vivo studies have revealed that these proteins are molecular switches that have discrete functional states that impart different effects on downstream ion channels, transporters, and the paracellular pathway. These effects enable the distal nephron to allow either maximal NaCl reabsorption or maximal K+ secretion in response to hypovolemia or hyperkalemia, respectively. The related kinase WNK3 has reciprocal actions on the primary mediators of cellular Cl− influx and efflux, effects that can serve to regulate cell volume during growth and in response to osmotic stress as well as to modulate neuronal responses to GABA. These findings define a versatile new family of kinases that coordinate the activities of diverse ion transport pathways to achieve and maintain fluid and electrolyte homeostasis.
Genetic variation in endocannabinoid metabolism, gastrointestinal motility, and sensation
Authors: Camilleri Michael , Carlson Paula , McKinzie Sanna , Grudell April , Busciglio Irene , Burton Duane , Baxter Kari , Ryks Michael , Zinsmeister Alan R.
Published: October 2007

Cannabinoid agonist inhibits gastrointestinal motility. The endocannabinoid, anandamide, is inactivated by fatty acid amide hydrolase (FAAH). A single nucleotide polymorphism in the human FAAH gene (C385A) reduces FAAH expression. Our aim was to evaluate associations between FAAH genotype variation and symptom phenotype, gastric emptying and volume, colonic transit, and rectal sensation in patients with functional gastrointestinal disorders (FGID). 482 FGID patients [Rome II positive, 159 constipation disorders, 184 diarrhea disorders (D-IBS), 86 mixed bowel function (M-IBS), 20 chronic abdominal pain (CAP), 33 functional dyspepsia], and 252 healthy volunteers (HV) underwent questionnaires and studies of phenotype and genotype from 2000 to 2007: 250 gastric emptying, 210 fasting and postprandial gastric volume, 152 colonic transit, and 123 rectal sensation. All had FAAH genotype [CC vs. polymorphic (CA/AA)] determined by TaqMan. FAAH genotype distribution of FGID patients and HV did not deviate from Hardy-Weinberg equilibrium. There was a significant association of FAAH genotype with FGID phenotype (overall χ2, P = 0.011) and with specific individual phenotypes ( P = 0.048). Thus FAAH CA/AA increases the odds (relative to HV) for D-IBS ( P = 0.008), M-IBS ( P = 0.012), and, possibly, CAP ( P = 0.055). There was a significant association of FAAH CA/AA genotype with accelerated colonic transit in D-IBS ( P = 0.037). There was no association of FAAH genotype with rectal sensation thresholds or ratings. The association of genetic variation in metabolism of endocannabinoids with symptom phenotype in D-IBS and M-IBS and with faster colonic transit in D-IBS supports the hypothesis that cannabinoid mechanisms may play a role in the control of colonic motility in humans and deserve further study.
Protease-activated receptor 1 knockout reduces experimentally induced liver fibrosis
Authors: Rullier Anne , Gillibert-Duplantier Jennifer , Costet Pierre , Cubel Gaëlle , Haurie Valérie , Petibois Cyril , Taras Danièle , Dugot-Senant Nathalie , Deleris Gérard , Bioulac-Sage Paulette , Rosenbaum Jean
Published: October 2007

Thrombin inhibition protects against liver fibrosis. However, it is not known whether the thrombin profibrogenic effect is due to effects on blood coagulation or to signaling via protease-activated receptors (PARs). We took advantage of the lack of blood coagulation defects in PAR-1-knockout mice. Acute carbon tetrachloride (CCl4) toxicity was similar in wild-type (WT), PAR-1−/−, and PAR-1+/−mice as judged by aminotransferase levels, area of liver necrosis, and liver peroxidation measured by Fourier-transformed infrared spectroscopy. Fifteen mice/group received CCl4or its solvent for 6 wk (300 μl/kg, 3 times a week). Fibrosis area was increased 10-fold by CCl4treatment in WT mice. PAR-1 deficiency protected against fibrosis, with 36% and 56% decrease in PAR-1+/−and PAR-1−/−mice, respectively ( P < 0.001). Similar results were obtained for area of activated fibrogenic cells (64% and 79% decrease in PAR-1+/−and PAR-1−/−mice, respectively, P < 0.001). These findings were corroborated by measurements of type I collagen, matrix metalloproteinase-2, and PDGF-β receptor mRNA levels. There was also a significant decrease in T lymphocyte infiltration in PAR-1-deficient mice. Altogether, these results suggest that thrombin profibrogenic effects are independent of effects on blood coagulation and are instead due to direct effects on fibrogenic cells and possibly on T lymphocytes.
Laryngeal apnea in rat pups: effects of age and body temperature
Authors: Xia Luxi , Leiter James C. , Bartlett Donald
Published: October 2007

In neonatal mammals of many species, including human infants, apnea and other reflex responses frequently arise from stimulation of laryngeal receptors by ingested or regurgitated liquids. These reflexes, mediated by afferents in the superior laryngeal nerves (SLNs), are collectively known as the laryngeal chemoreflex (LCR) and are suspected to be responsible for some cases of the sudden infant death syndrome (SIDS). The LCR is strongly enhanced by mild increases in body temperature in decerebrate piglets, a finding that is of interest because SIDS victims are often found in overheated environments. Because of the experimental advantages of studying reflex development and mechanisms in neonatal rodents, we have developed methods for eliciting laryngeal apnea in anesthetized rat pups and have examined the influence of mild hyperthermia in animals ranging in age from 3 to 21 days. We found that apnea and respiratory disruption, elicited either by intralaryngeal water or by electrical stimulation of the SLN, occurred at all ages studied. Raising body temperature by 2–3°C prolonged the respiratory disturbance in response to either stimulus. This effect of hyperthermia was prominent in the youngest animals and diminished with age. We conclude that many studies of the LCR restricted to larger neonatal animals in the past can be performed in infant rodents using appropriate methods. Moreover, the developmental changes in the LCR and in the thermal modulation of the LCR seem to follow different temporal profiles, implying that distinct neurophysiological processes may mediate the LCR and thermal prolongation of the LCR.
Unrestrained video-assisted plethysmography: a noninvasive method for assessment of lung mechanical function in small animals
Authors: Bates Jason H. T. , Thompson-Figueroa John , Lundblad Lennart K. A. , Irvin Charles G.
Published: October 2007

The assessment of lung mechanical function in small animals, particularly mice, is essential for investigations into the pathophysiology of pulmonary disease. The most accurate and specific methods for making this assessment are highly invasive and so provide data of questionable relevance to normality. By contrast, present noninvasive methods based on unrestrained plethysmography have no direct link to the mechanical properties of the lung. There is thus a need for a completely noninvasive method for determining lung mechanical function in small animals. In the present study, we demonstrate an extension of unrestrained plethysmography in which changes in lung volume are estimated via orthogonal video imaging of the thorax. These estimates are combined with the pressure swings recorded as mice breathe inside a heated and humidified chamber to yield an estimate of specific airway resistance (sRaw). We used this new technique, which we term “unrestrained video-assisted plethysmography” (UVAP), to measure sRaw in 11 BALB/c mice exposed to aerosols of saline, methacholine, and albuterol and obtained mean values of 0.71, 1.23 and 1.10 cmH2O·s, respectively. Mean breathing frequency was 4.3, 3.4, and 3.6 breaths/s, respectively, while the corresponding mean tidal volumes were 0.36, 0.44 and 0.37 ml, respectively. We conclude that UVAP, a noninvasive method, is able to provide usefully accurate estimates of sRaw and breathing pattern parameters in mice.
Acoustic plethysmography measures breathing in unrestrained neonatal mice
Authors: Daubenspeck J. Andrew , Li Aihua , Nattie Eugene E.
Published: October 2007

Measurement of breathing volumes in neonatal mice is of growing importance in order to characterize the influence of development and genetic modifications on respiratory control to evaluate hypotheses concerned with human infant deficits that may affect sudden infant death syndrome, for example. Current techniques require undesirable physical constraints or incur possible artifacts specific to very small animals. We have examined the utility of a recently proposed approach using an acoustic resonance procedure that does not require undue physical constraint beyond placement in the acoustic plethysmograph. We show here that this approach can be applied to baby mice 5 days after birth and that it can be accurately calibrated. In addition, this approach should be useful to study unrestrained neonatal mice under conditions where body temperature approaches environmental temperature and barometric plethysmography cannot be used.
Hyperthermia and fatigue
Authors: Nybo Lars
Published: October 2007

The present review addresses mechanisms of importance for hyperthermia-induced fatigue during short intense activities and prolonged exercise in the heat. Inferior performance during physical activities with intensities that elicit maximal oxygen uptake is to a large extent related to perturbation of the cardiovascular function, which eventually reduces arterial oxygen delivery to the exercising muscles. Accordingly, aerobic energy turnover is impaired and anaerobic metabolism provokes peripheral fatigue. In contrast, metabolic disturbances of muscle homeostasis are less important during prolonged exercise in the heat, because increased oxygen extraction compensates for the reduction in systemic blood flow. The decrease in endurance seems to involve changes in the function of the central nervous system (CNS) that lead to fatigue. The CNS fatigue appears to be influenced by neurotransmitter activity of the dopaminergic system, but may primarily relate to inhibitory signals from the hypothalamus arising secondary to an increase in brain temperature. Fatigue is an integrated phenomenon, and psychological factors, including the anticipation of fatigue, should not be neglected and the interaction between central and peripheral physiological factors also needs to be considered.
On Boundaries of Parallelizable Regions of Flows of Free Mappings
Authors: Leśniak Zbigniew
Published: October 2007

We are interested in the first prolongational limit set of the boundary of parallelizable regions of a given flow of the plane which has no fixed points. We prove that for every point from the boundary of a maximal parallelizable region, there exists exactly one orbit contained in this region which is a subset of the first prolongational limit set of the point. Using these uniquely determined orbits, we study the structure of maximal parallelizable regions.
Detection of Surface Defects on Compact Discs
Authors: Odgaard P. F. , Stoustrup J. , Andersen P.
Published: October 2007

Online detection of surface defects on optical discs is of high importance for the accommodation schemes handling these defects. These surface defects introduce defect components to the position measurements of focus and radial tracking positions. The respective controllers will accordingly try to suppress these defect components resulting in a wrong positioning of the optical disc drive. In this paper, two novel schemes for detecting these surface defects are introduced and compared. Both methods, which are an extended threshold scheme and a wavelet packet-based scheme, improve the detection compared with a standard threshold scheme. The extended threshold scheme detects the four tested defects with a maximal detection delay of 3 samples while the wavelet packet-based scheme has a maximal detection delay of 6 samples. Simulations of focus and radial positions in the presence of a surface defect are performed in order to inspect the importance and consequences of the size of the detection delay, from which it can be seen that focus and radial position errors increase significantly due to the defect as the detection delay increases.
On Minimal Norms onMn
Authors: Mirzavaziri Madjid , Moslehian Mohammad Sal
Published: October 2007

We show that for each minimal normN(⋅)on the algebraℳnof alln×ncomplex matrices, there exist norms‖⋅‖1and‖⋅‖2onℂnsuch thatN(A)=max{‖Ax‖2:‖x‖1=1, x∈ℂn}for allA∈ℳn. This may be regarded as an extension of a known result on characterization of minimal algebra norms.
Clustering‐Based Linear Least Square Fitting Method for Generation of Parametric Images in Dynamic FDG PET Studies
Authors: Huang Xinrui , Zhou Yun , Bao Shangliang , Huang Sung-Cheng
Published: October 2007

Parametric images generated from dynamic positron emission tomography (PET) studies are useful for presenting functional/biological information in the 3‐dimensional space, but usually suffer from their high sensitivity to image noise. To improve the quality of these images, we proposed in this study a modified linear least square (LLS) fitting method named cLLS that incorporates a clustering‐based spatial constraint for generation of parametric images from dynamic PET data of high noise levels. In this method, the combination of K‐means and hierarchical cluster analysis was used to classify dynamic PET data. Compared with conventional LLS, cLLS can achieve high statistical reliability in the generated parametric images without incurring a high computational burden. The effectiveness of the method was demonstrated both with computer simulation and with a human brain dynamic FDG PET study. The cLLS method is expected to be useful for generation of parametric images from dynamic FDG PET study.
Magnetic Resonance Imaging of Endothelial Adhesion Molecules in Mouse Atherosclerosis Using Dual-Targeted Microparticles of Iron Oxide
Authors: McAteer Martina A. , Schneider Jurgen E. , Ali Ziad A. , Warrick Nicholas , Bursill Christina A. , von zur Muhlen Constantin , Greaves David R. , Neubauer Stefan , Channon Keith M. , Choudhury Robin P.
Published: October 2007

Objective—

Microparticles of iron oxide (MPIO) distort magnetic field creating marked contrast effects far exceeding their physical size. We hypothesized that antibody-conjugated MPIO would enable magnetic resonance imaging (MRI) of endothelial cell adhesion molecules in mouse atherosclerosis.

Methods and Results—

MPIO (4.5 μm) were conjugated to monoclonal antibodies against vascular cell adhesion molecule-1 (VCAM–MPIO) or P-selectin (P-selectin–MPIO). In vitro, VCAM–MPIO bound, in dose-dependent manner, to tumor necrosis factor (TNF)-α stimulated sEND-1 endothelial cells, as quantified by light microscopy (
R
2
=0.94,
P
=0.03) and by MRI (
R
2
=0.98,
P
=0.01). VCAM–MPIO binding was blocked by preincubation with soluble VCAM-1. To mimic leukocyte binding, MPIO targeting both VCAM-1 and P-selectin were administered in apolipoprotein E
−/−
mice. By light microscopy, dual-targeted MPIO binding to endothelium overlying aortic root atherosclerosis was 5- to 7-fold more than P-selectin–MPIO (
P
<0.05) or VCAM–MPIO (
P
<0.01) alone. Dual-targeted MPIO, injected intravenously in vivo bound aortic root endothelium and were quantifiable by MRI ex vivo (3.5-fold increase versus control;
P
<0.01). MPIO were well-tolerated in vivo, with sequestration in the spleen after 24 hours.

Conclusions—

Dual-ligand MPIO bound to endothelium over atherosclerosis in vivo, under flow conditions. MPIO may provide a functional MRI probe for detecting endothelial-specific markers in a range of vascular pathologies.
The Mechanistic Basis for the Disparate Effects of Angiotensin II on Coronary Collateral Growth
Authors: Reed Ryan , Kolz Christopher , Potter Barry , Rocic Petra
Published: October 2007

Objective—

We hypothesize that controversial effects of angiotensin II (Ang II) are attributable to its regulation of reactive oxygen species (ROS) and ROS-dependent signaling.

Methods and Results—

Coronary collateral growth (CCG) was stimulated in normal (WKY) and syndrome X (JCR) rats by transient/repetitive ischemia (RI). Blood flow was measured in the normal (NZ) and the collateral-dependent (CZ) zone. In WKY, RI increased CZ flow (0.84 mL/min/g), but RI+subpressor Ang II increased it more (1.24 mL/min/g). This was associated with transient p38 and sustained Akt activation. A hypertensive dose of Ang II decreased CZ flow (0.69 mL/min/g), which was associated with sustained p38 and transient Akt activation. AT1R blockade by candesartan abrogated CZ flow in WKY (0.58 mL/min/g), reduced myocardial superoxide, and blocked p38 and Akt activation. RI-induced CZ flow in JCR was significantly decreased compared with WKY (0.12 mL/min/g), associated with a large increase in superoxide and lack of p38 and Akt activation. CZ flow in JCR was partially restored by candesartan (0.45 mL/min/g), accompanied by reduction in superoxide and partial restoration of p38 and Akt activation.

Conclusion—

Ang II/AT1R blockade, at least in part, regulates CCG via generating optimal ROS amounts and activating redox-sensitive signaling.
Persistent Regional Downregulation in Mitochondrial Enzymes and Upregulation of Stress Proteins in Swine With Chronic Hibernating Myocardium
Authors: Page Brian , Young Rebeccah , Iyer Vijay , Suzuki Gen , Lis Maciej , Korotchkina Lioubov , Patel Mulchand S. , Blumenthal Kenneth M. , Fallavollita James A. , Canty John M.
Published: October 2007

Hibernating myocardium is accompanied by a downregulation in energy utilization that prevents the immediate development of ischemia during stress at the expense of an attenuated level of regional contractile function. We used a discovery based proteomic approach to identify novel regional molecular adaptations responsible for this phenomenon in subendocardial samples from swine instrumented with a chronic LAD stenosis. After 3 months (n=8), hibernating myocardium was present as reflected by reduced resting LAD flow (0.75±0.14 versus 1.19±0.14 mL · min
−1
· g
−1
in remote) and wall thickening (1.93±0.46 mm versus 5.46±0.41 mm in remote,
P
<0.05). Regionally altered proteins were quantified with 2D Differential-in-Gel Electrophoresis (2D-DIGE) using normal myocardium as a reference with identification of candidates using MALDI-TOF mass spectrometry. Hibernating myocardium developed a significant downregulation of many mitochondrial proteins and an upregulation of stress proteins. Of particular note, the major entry points to oxidative metabolism (eg, pyruvate dehydrogenase complex and Acyl-CoA dehydrogenase) and enzymes involved in electron transport (eg, complexes I, III, and V) were reduced (
P
<0.05). Multiple subunits within an enzyme complex frequently showed a concordant downregulation in abundance leading to an amplification of their cumulative effects on activity (eg, “total” LAD PDC activity was 21.9±3.1 versus 42.8±1.9 mU,
P
<0.05). After 5-months (n=10), changes in mitochondrial and stress proteins persisted whereas cytoskeletal proteins (eg, desmin and vimentin) normalized. These data indicate that the proteomic phenotype of hibernating myocardium is dynamic and has similarities to global changes in energy substrate metabolism and function in the advanced failing heart. These proteomic changes may limit oxidative injury and apoptosis and impact functional recovery after revascularization.
Electrostatic Contributions of Aromatic Residues in the Local Anesthetic Receptor of Voltage-Gated Sodium Channels
Authors: Ahern Christopher A. , Eastwood Amy L. , Dougherty Dennis A. , Horn Richard
Published: October 2007

Antiarrhythmics, anticonvulsants, and local anesthetics target voltage-gated sodium channels, decreasing excitability of nerve and muscle cells. Channel inhibition by members of this family of cationic, hydrophobic drugs relies on the presence of highly conserved aromatic residues in the pore-lining S6 segment of the fourth homologous domain of the channel. We tested whether channel inhibition was facilitated by an electrostatic attraction between lidocaine and π electrons of the aromatic rings of these residues, namely a cation-π interaction. To this end, we used the in vivo nonsense suppression method to incorporate a series of unnatural phenylalanine derivatives designed to systematically reduce the negative electrostatic potential on the face of the aromatic ring. In contrast to standard point mutations at the same sites, these subtly altered amino acids preserve the wild-type voltage dependence of channel activation and inactivation. Although these phenylalanine derivatives have no effect on low-affinity tonic inhibition by lidocaine or its permanently charged derivative QX-314 at any of the substituted sites, high-affinity use-dependent inhibition displays substantial cation-π energetics for 1 residue only: Phe1579 in rNaV1.4. Replacement of the aromatic ring of Phe1579 by cyclohexane, for example, strongly reduces use-dependent inhibition and speeds recovery of lidocaine-engaged channels. Channel block by the neutral local anesthetic benzocaine is unaffected by the distribution of π electrons at Phe1579, indicating that our aromatic manipulations expose electrostatic contributions to channel inhibition. These results fine tune our understanding of local anesthetic inhibition of voltage-gated sodium channels and will help the design of safer and more salutary therapeutic agents.
Prevention of Dystrophin-Deficient Cardiomyopathy in Twenty-One-Month-Old Carrier Mice by Mosaic Dystrophin Expression or Complementary Dystrophin/Utrophin Expression
Authors: Bostick Brian , Yue Yongping , Long Chun , Duan Dongsheng
Published: October 2007

A cure for dystrophin-deficient muscular dystrophy requires treating both skeletal muscle and the heart. Whereas mosaic dystrophin expression has been shown to protect skeletal muscle, controversy exists over whether mosaic expression is protective in the heart. We have shown recently that mosaic dystrophin expression prevents stress-induced heart damage in young carrier mice. Although an interesting finding, the clinical relevance remains to be established because young dystrophin-null
mdx
mice do not have heart disease. On the other hand, heart failure has been reported in human carriers. To resolve this mouse/human discrepancy, we evaluated the cardiac phenotype in 21-month-old
mdx
, carrier, and normal mice. We found dilated cardiomyopathy in old
mdx
mice but not in age-matched carrier mice. All anatomical parameters and physiological assay results (ECG and closed-chest Millar catheter) were within the normal range in old carrier mice. Focal myocardial inflammation was found in a small fraction of old carrier mice, but it had no major impact on heart function. Dobutamine stress revealed a near normal hemodynamic profile except for a marginal reduction in systolic pressure in old carrier mice. Immunostaining and Western blot showed dystrophin expression in 50% cardiomyocytes in old carrier mice. Interestingly, utrophin was upregulated in dystrophin-negative heart cells in carrier mice. In summary, we have provided the first clear-cut evidence that dilated cardiomyopathy in old
mdx
mice was prevented by mosaic dystrophin expression or complementary dystrophin/utrophin expression. Our results raise the hope for ameliorating dystrophic cardiomyopathy through partial gene and/or cell therapy.
Cardioprotection by Ischemic Postconditioning Is Lost in Aged and STAT3-Deficient Mice
Authors: Boengler Kerstin , Buechert Astrid , Heinen Yvonne , Roeskes Christin , Hilfiker-Kleiner Denise , Heusch Gerd , Schulz Rainer
Published: October 2007

The cardioprotection by ischemic preconditioning is lost in aged wild-type and in STAT3 (signal transducer and activator of transcription 3)-deficient mice. The aim of the present study was to analyze whether or not ischemic postconditioning (iPoco) was effective in aged mice hearts and whether iPoco was dependent on STAT3. Young (3 months) and aged (>13 months) C57Bl6/J mice underwent 30 minutes of ischemia and 2 hours of reperfusion without or with iPoco (3 cycles of 10 seconds of ischemia/10 seconds of reperfusion [3×10] or 5 cycles of 5 seconds of ischemia/5 seconds of reperfusion [5×5] at the beginning of reperfusion). In young mice, both iPoco3×10 and iPoco5×5 reduced infarct size (IS), whereas in aged mice, only iPoco5×5 was effective in reducing IS. In young mice, iPoco3×10 increased the phosphorylated over total STAT3 (phosphorylated STAT3/STAT3) ratio at 10 minutes of reperfusion in the postconditioned anterior wall compared with the control posterior wall. In aged mice hearts, total STAT3 and phosphorylated STAT3/STAT3 in the anterior wall at reperfusion were reduced compared with young mice hearts. In young mice hearts subjected to iPoco3×10 but pretreated with the JAK-2 inhibitor AG-490, phosphorylated STAT3/STAT3 was reduced in the anterior wall compared with untreated young mice hearts, and IS reduction by iPoco3×10 was abolished. Furthermore, in young mice with a cardiomyocyte-restricted deletion of STAT3, iPoco3×10 failed to reduce IS, whereas iPoco5×5 reduced IS. Thus, cardioprotection by iPoco is dependent on the postconditioning protocol in aged and STAT3-deficient hearts. The reduced levels of STAT3 with increasing age may contribute to the age-related loss of iPoco.
Incidence of Hemorrhagic Stroke in Black Caribbean, Black African, and White Populations
Authors: Smeeton Nigel C. , Heuschmann Peter U. , Rudd Anthony G. , McEvoy Andrew W. , Kitchen Neil D. , Sarker Shah Jalal , Wolfe Charles D.A.
Published: October 2007

Background and Purpose—

Data are lacking on the differences in hemorrhagic stroke incidence between black Caribbean (BC), black African (BA), and white ethnic groups. We estimated the incidence for primary intracerebral hemorrhage (PICH) and subarachnoid hemorrhage (SAH) and the associated risk factors for BCs, BAs, and whites.

Methods—

First-ever stroke patients were drawn from a prospective community stroke register based in a multiethnic population in South London with 9% BCs, 15% BAs, and 63% whites. Incidence rates were standardized to European and world populations and adjusted for age and sex. Incidence rate ratios (IRRs) relative to whites were calculated by Poisson regression.

Results—

Between 1995 and 2004, 566 incident stroke patients were registered: 395 PICHs and 171 SAHs. For PICH, age- and sex-adjusted IRRs were higher in BAs (IRR, 2.80; 95% CI, 2.00 to 3.91) than in BCs (IRR, 1.46; 95% CI, 1.07 to 1.99) and were particularly pronounced for patients age 0 to 64 years: IRR=3.95 (95% CI, 2.65 to 5.87) in BAs and 2.38 (95% CI, 1.50 to 3.80) in BCs. For those <65 years, prestroke hypertension was more prevalent in BAs and BCs (
P
=0.049). For SAH, the IRR was higher in BCs (IRR; 1.62; 95% CI, 1.05 to 2.48) than in BAs (IRR, 0.80; 95% CI, 0.43 to 1.46).

Conclusions—

The higher incidence of PICH observed in BCs and BAs could be explained by prestroke hypertension being more common among young blacks. The different incidences of SAH in BCs and BAs suggest that the baseline risk of stroke for distinct black ethnic groups is not homogeneous.
Patterns and Predictors of Early Risk of Recurrence After Transient Ischemic Attack With Respect to Etiologic Subtypes
Authors: Purroy Francisco , Montaner Joan , Molina Carlos A. , Delgado Pilar , Ribo Marc , Álvarez-Sabín José
Published: October 2007

Background and Purpose—

The risk of recurrent stroke is highest within the first few weeks after a transient ischemic attack (TIA), and it is likely to be related to the underlying pathology. We sought to study the early risk of recurrent stroke by etiologic subtype.

Methods—

We prospectively studied 388 TIA patients. The cause of TIA was classified according to the Trial of ORG 10172 criteria: large-artery atherosclerosis (LAA, n=90), cardioembolism (n=87), small-vessel disease (n=68), undetermined (n=127), and other determined cause (n=16). Patients were followed up at 3 months. Risk factors and clinical symptoms for each subtype were recorded.

Results—

The duration of symptoms and clinical symptoms varied significantly among the different subtypes. LAA was associated with recurrent short episodes of weakness, whereas speech impairment and cortical symptoms were associated with cardioembolism (
P
<0.05). The association of vascular risk factors was highest in LAA (
P
<0.05). New strokes were recorded in 35 (9%) patients. Recurrent stroke risk varied among subtypes (
P
<0.001): LAA, 20.0%; cardioembolism, 11.5%; undetermined, 4.7%; small-vessel disease, 1.5%; and other cause, 0%. Cox proportional-hazards multivariate analyses did not identify any independent predictor of further cerebral ischemic events for LAA, cardioembolism, undetermined, or small-vessel disease.

Conclusions—

The risk of early recurrent stroke is highest in patients with LAA. This supports the need for urgent carotid and transcranial imaging for identifying those patients at highest risk. Some risk factors and clinical symptoms are related to some etiologic subtypes, but stronger predictors of stroke recurrence are needed to identify those patients with highest risk for each TIA subtype.