bluuebunny/crossref_metadata_2025 huggingface dataset:
Glucose kinetics and exercise tolerance in mice lacking the GLUT4 glucose transporter
Authors: Fueger Patrick T. , Li Candice Y. , Ayala Julio E. , Shearer Jane , Bracy Deanna P. , Charron Maureen J. , Rottman Jeffrey N. , Wasserman David H.
Published: May 2007

The absence of GLUT4 severely impairs basal glucose uptake in vivo, but does not alter glucose homeostasis or circulating insulin. Glucose uptake in isolated contracting skeletal muscle (MGU) is also impaired by the absence of GLUT4, and onset of muscle fatigue is hastened. Whether the body can compensate and preserve glucose homeostasis during exercise, as it does in the basal state, is unknown. One aim was to test the effectiveness of glucoregulatory compensation for the absence of GLUT4 in vivo. The absence of GLUT4 was also used to further define the role of hexokinase (HK) II, which catalyses glucose phosphorylation after it is transported in the cell. HK II increases MGU during exercise, as well as exercise endurance. In the absence of GLUT4, HK II expression will not affect MGU. A second aim was to test whether, in the absence of GLUT4, HK II retains its ability to increase exercise endurance. Wild‐type (WT), GLUT4 null (GLUT4−/−), and GLUT4 null overexpressing HK II (GLUT4−/−HKTg) mice were studied using a catheterized mouse model that allows blood sampling and isotope infusions during treadmill exercise. The impaired capacity of working muscle to take up glucose in GLUT4−/− is partially offset by an exaggerated increase in the glucagon: insulin ratio, increased liver glucose production, hyperglycaemia, and a greater capillary density in order to increase the delivery of glucose to the exercising muscle of GLUT4−/−. Hearts of GLUT4−/− also exhibited a compensatory increase in HK II expression and a paradoxical increase in glucose uptake. Exercise tolerance was reduced in GLUT4−/− compared to WT. As expected, MGU in GLUT4−/−HKTg was the same as in GLUT4−/−. However, HK II overexpression retained its ability to increase exercise endurance. In conclusion, unlike the basal state where glucose homeostasis is preserved, hyperglycaemia results during exercise in GLUT4−/− due to a robust stimulation of liver glucose release in the face of severe impairments in MGU. Finally, studies in GLUT4−/−HKTg show that HK II improves exercise tolerance, independent of its effects on MGU.
Deciphering the nitric oxide to carbon monoxide lung transfer ratio: physiological implications
Authors: Glénet Stéphane N. , De Bisschop Claire , Vargas Frederic , Guénard Hervé J. P.
Published: May 2007

Using simultaneous nitric oxide and carbon monoxide lung transfer measurements (TLNO and TLCO), the membrane transfer capacity (Dm) and capillary lung volume (Vc) as well as the dimensionless ratio TLNO/TLCO can be calculated. The significance of this ratio is yet unclear. Theoretically, the TLNO/TLCO ratio should be inversely related to the product of  both lung alveolar capillary membrane (μ) and blood sheet thicknesses (K). NO and CO transfers were measured in healthy subjects in various conditions likely to be associated with changes in K and/or μ. Experimentally, deflation of the lung from 7.4 to 4.8 l decreased the TLNO/TLCO ratio from 4.9 to 4.2 (n= 25) which was consistent mainly with a thickening of the blood sheet. Compared with continuous negative pressure breathing, continuous positive pressure breathing increased this ratio suggesting a thinning of the capillary sheet. It was also observed with 12 healthy subjects that slight haemodilution that may thicken the blood sheet decreased the TLNO/TLCO ratio from 4.85 to 4.52. In conclusion, the TLNO/TLCO ratio is related to the thickness of the alveolar blood barrier. This ratio provides novel information for the analysis of the diffusion properties.
On an identity for the volume integral of the square of a vector field
Authors: Stewart A. M.
Published: May 2007

A proof is given of the vector identity proposed by Gubarev, Stodolsky, and Zakarov that relates the volume integral of the square of a three-vector field to nonlocal integrals of the curl and divergence of the field. The identity is applied to the vector potential and magnetic field of a rotating charged shell. The latter provides a straightforward application of the use of the addition theorem of spherical harmonics.
A lesson in the physics laboratory on the superheating of water
Authors: Gianino Concetto
Published: May 2007

The theory of water vaporization is used to understand the phenomenon of boiling and the mechanisms of bubble formation. A simple experiment was done to verify the theory and measure the bubble radius under superheating conditions. Experimental results are in good agreement with calculated values.
Missing Mass in Collisional Debris from Galaxies
Authors: Bournaud Frédéric , Duc Pierre-Alain , Brinks Elias , Boquien Médéric , Amram Philippe , Lisenfeld Ute , Koribalski Bärbel S. , Walter Fabian , Charmandaris Vassilis
Published: May 2007

Recycled dwarf galaxies can form in the collisional debris of massive galaxies. Theoretical models predict that, contrary to classical galaxies, these recycled galaxies should be free of nonbaryonic dark matter. By analyzing the observed gas kinematics of such recycled galaxies with the help of a numerical model, we demonstrate that they do contain a massive dark component amounting to about twice the visible matter. Staying within the standard cosmological framework, this result most likely indicates the presence of large amounts of unseen, presumably cold, molecular gas. This additional mass should be present in the disks of their progenitor spiral galaxies, accounting for a substantial part of the so-called missing baryons.
Transgenic sequences are frequently lost inPhytophthora parasiticatransformants without reversion of the transgene-induced silenced state
Authors: Gaulin Elodie , Haget Nathalie , Khatib Moustafa , Herbert Corentin , Rickauer Martina , Bottin Arnaud
Published: May 2007

Little data exist on the mechanism and stability of transformation in Phytophthora parasitica, a major oomycete parasite of plants. Here, we studied the stability of drug-resistant protoplast transformants by analyzing single-zoospore derivatives. We show that the transgenic sequences are not stably integrated into the chromosomes, resulting in the loss of drug resistance in single-zoospore derivatives. However, in strains where the P. parasitica gene encoding the CBEL elicitor was silenced by transformation with sense or antisense constructs, silencing is not reversed when the transgenic sequences are lost. This suggests that instability of P. parasitica transformants is not an obstacle for loss-of-function studies in this organism.Key words: Phytophthora, transformation, sporulation, silencing, stability.
Haloarchaeal communities in the crystallizers of two adriatic solar salterns
Authors: Paić Lejla , Ulrih Nataa Poklar , Črnigoj Miha , Grabnar Miklav , Velikonja Blagajana Herzog
Published: May 2007

Solar salterns operate only for short dry periods of the year in the north shore of the Adriatic Sea because of its relatively humid and cold Mediterranean climate. In a previous paper, we showed that the NaCl precipitation ponds (crystallizers) of Northern Adriatic Sečovlje salterns have different haloarchaeal populations from those typically found in dry and hot climates such as Southern Spain. To check whether there is a common pattern of haloarchaeal diversity in these less extreme conditions, diversity in crystallizers of other Adriatic solar salterns in Ston, Croatia was ascertained by molecular and culture methods. In addition, the cultivation approach was used to further describe haloarchaeal diversity in both salterns. Over the period of two solar salt collection seasons, isolates related to species of the genera Haloferax, Haloarcula, and Haloterrigena were recovered from both salterns. Within the same sampling effort, relatives of the genus Halorubrum and a Natrinema-like isolate were cultivated from Slovenian Sečovlje salterns while Halobacterium related isolates were obtained from the Croatian Ston salterns. Concurrent with our previous findings, a library of Croatian saltern crystallizer PCR-amplified 16S rRNA genes was dominated by sequences related to the genus Halorubrum. The microbial community structure was similar in both salterns but diversity indices showed greater values in Slovenian salterns when compared with Croatian salterns.Key words: 16S rRNA, Haloarchaea, saltern, hypersaline, halophiles.
Microfungi associated with Abies needles and Betula leaf litter in a subalpine coniferous forest
Authors: Osono Takashi , Takeda Hiroshi
Published: May 2007

We investigated microfungal assemblages on leaf litter within a subalpine forest in central Japan and their variation with season, litter depth, and litter species. Microfungal assemblages were compared for Abies needles and Betula leaf litter collected from litter and fermentation layers of the forest floor during the growing season in spring, summer, and autumn. A total of 35 and 42 species were isolated from Abies needles and Betula leaf litter, respectively. The observed variation in microfungal assemblages was primarily attributable to seasonal differences. The frequencies of Trichoderma viride, Volutella ciliata, Mucor sp., and Umbelopsis ramanniana increased in summer, leading to a high degree of similarity of microfungal assemblages in different litter depths and litter species. Microfungal assemblages on Abies needles in spring and autumn and those on Betula leaves in spring were characterized by Trichoderma viride, V. ciliata, Thysanophora penicillioides, Trichoderma polysporum, and (or) Mortierella alpina. Microfungal assemblages on Betula leaves in autumn were characterized by the absence of these species and the occurrence of Cladosporium cladosporioides. The results were discussed with an emphasis on the role of microfungi in decomposition processes and the impact on fungi of predicted future increases in global temperature.Key words: birch, decomposition, diversity, fir, global warming.
Agrichemical impact on growth and survival of non-target apple phyllosphere microorganisms
Authors: Walter Monika , Frampton Christopher Miles , Boyd-Wilson Kirsty Sarah Helen , Harris-Virgin Patricia , Waipara Nicholas William
Published: May 2007

The impact of conventional agrichemicals commonly used in New Zealand apple production on non-target, culturable phyllosphere microbial populations was studied in the laboratory (agar, leaf, and seedling assays) and field (apple orchard). Morphologically distinct bacteria (three), yeasts (five), and filamentous microfungi (two) were used as indicator species. The agar assay showed that agrichemical toxicity to microorganisms was dependent on product type, product rate, and organism studied. While the fungicides metiram and captan stopped or severely reduced growth of nearly all microorganisms studied, the insecticides tebufenozide and lufenuron and the fungicide nitrothal-isopropyl showed the least amount of microbial toxicity, each affecting 2 of the 10 indicator organisms studied. In the leaf assay a single agrichemical application at field rate either reduced or increased microbial population counts, again depending on product and microorganism. Repeated agrichemical applications, however, reduced microbial population numbers from 10- to 10 000-fold in planta. Further field research validated these findings, although differences in microbial numbers before and after agrichemical applications were less dramatic. In the orchard, total organism numbers recovered within 2–6 days, but species richness (sum of recognizable taxonomic units) declined. Agrichemicals clearly affected non-target, culturable surface microorganisms. The importance of diversity and stability of microbial populations for disease control still needs to be established.Key words: apple, microbial abundance, microbial richness, 6-benzyladenine, buprofezin, captan, cyprodinil, difenoconazole, dithianon, dodine, kresoxim-methyl, lufenuron, metiram, myclobutanil, nitrothal-isopropyl, tebufenozide, triadimefon.
Effect of water activity and temperature on growth of Penicillium citreoviride and Penicillium citrinum on MiGao (rice cake)
Authors: Ji Ying , Zhu Kexue , Qian Haifeng , Zhou Huiming
Published: May 2007

Contamination by mold is a serious problem in steam-cooked rice cake, a traditional Chinese food. Growth responses to different temperatures and water activity values for Penicillium citreoviride and Penicillium citrinum , two of the most common molds, were investigated. Partial least square regression analysis showed that the growth of the two fungi did not differ in response to changes in water activity and temperature. Optimum water activity for growth was 0.90 and optimum temperatures for growth were 30 °C in most cases.
Phylogenetic relationships ofCampylobacter jejunibased onporAsequences
Authors: Clark Clifford G , Beeston Anne , Bryden Louis , Wang Gehua , Barton Connie , Cuff Wilfred , Gilmour Matthew W , Ng Lai-King
Published: May 2007

Campylobacter porins are the dominant major outer membrane protein (MOMP) of these bacteria. They are composed of hypervariable, surface-exposed, peptide loops and membrane-embedded, conserved peptide regions. Porins are functionally important and may also be useful for molecular subtyping methods but have not yet been well characterized. We therefore sequenced the porA gene from 39 Campylobacter isolates, including multilocus sequence type (MLST) reference strains, isolates from patients with the Guillain-Barré syndrome, other clinical isolates, and serotyping reference strains. These were compared with additional sequences available from GenBank. Three distinct porA lineages were observed after phylogenetic analysis. Both Campylobacter coli and Campylobacter jejuni were found with group 3 porA sequences, and this was the only group showing any evidence of recombination among porA genes. There was no recombination between porA genes from C. jejuni groups 1 and 2, suggesting there may be functional constraints on changes at this locus. Most of the amino acid differences among the three groups were present in surface-exposed loops, and dissimilar substitutions were found when groups 1 and 2 MOMP were compared. Different MOMP sequence groups may have different biological or antigenic properties, which in turn may be associated with survival in different environments, host adaptation, or virulence.Key words: Campylobacter, porin, major outer membrane protein, phylogenetic analysis.
Sampling bias created by ampicillin in isolation media forAeromonas
Authors: Huddleston Jennifer R , Zak John C , Jeter Randall M
Published: May 2007

Members of the bacterial genus Aeromonas are widely isolated from aquatic environments and studied in part for their ability to act as opportunistic pathogens in a variety of animals. All aeromonads, with the exception of Aeromonas trota, are generally thought to be resistant to ampicillin, so the antibiotic is frequently added to isolation medium as a selective agent. In this study, 282 aeromonads from environmental sources were isolated on a medium without ampicillin and their resistance to ampicillin determined. Of the 104 of these isolates that were judged to be independent (nonredundant), 18 (17.3%) were susceptible to ampicillin. A chi-square analysis was performed to determine the impact of ampicillin use on enumerating Aeromonas species from environmental samples. Our results indicate that, when ampicillin is used as a selective agent, a significant portion of the aeromonad population in at least some environ ments can be omitted from isolation.Key words: Aeromonas, ampicillin, selective media.
Novel soil lineages ofArchaeaare present in semi-arid soils of eastern Australia
Authors: Midgley David J , Saleeba Jennifer A , Stewart Michael I , McGee Peter A
Published: May 2007

The diversity of Archaea was studied in vertisolic and loam soils of a semi-arid region in Australia. Sampling was undertaken at an agricultural site, two grassland environments, and a brigalow (Acacia harpophylla) woodland. Archaeal community structure was profiled using amplified ribosomal DNA restriction analysis (ARDRA) combined with rDNA sequencing of an example of each restriction fragment length polymorphism type. Sequence comparison and phylogenetic analysis demonstrated that both crenarchaeotal and euryarchaeotal Archaea were present at oxic depths in the soil at all field sites. Along with previously described soil archaeal lineages, novel soil lineages and the deeply divergent Pendant-33 group of Euryarchaeota were also detected. A novel statistical method for comparing ARDRA derived data was demonstrated and implemented using the archaeal communities from the four field sites. Archaeal diversity, as measured by this method, was significantly higher in the agricultural site than at either of the grassland sites or the brigalow woodland.Key words: archaeal communities, cotton, Euryarchaeota, Crenarchaeota, soil.
Identification of mycobacteria in peat moss processing plants: application of molecular biology approaches
Authors: Cayer Marie-Pierre , Veillette Marc , Pageau Pascal , Hamelin Richard , Bergeron Marie-Josée , Mériaux Anne , Cormier Yvon , Duchaine Caroline
Published: May 2007

Peat moss processing plant workers are exposed to high concentrations of bioaerosols. Although mycobacteria have been cultured from peat moss, no study has examined the workers' exposure to mycobacterial bioaerosols. We evaluated the presence of mycobacteria in air samples from peat moss processing plants using molecular biology approaches (cloning-sequencing and polymerase chain reaction (PCR)) and the workers exposure using immunoglobulin G (IgG) complexes to mycobacteria. In addition, species detected in air samples and in peat moss were compared. Two peat moss processing plants were chosen among 14 previously studied. A total of 49 clones were sequenced. Real-time PCR was also performed on the same air samples to evaluate the airborne concentration of mycobacteria and estimate exposure levels. Several Mycobacterium species were present in the air samples (M. malmoense, M. smegmatis, M. graceum, M. bohemicum, and M. interjectum). Mycobacterium avium was recovered by culture in peat moss but not in the air using the molecular approach. Total airborne Mycobacterium concentration was estimated at 8.2 × 108/m3. Workers had IgG against the mycobacterial mix and M. avium, suggesting significant exposure. The findings from air samples, supported by IgG measurements, demonstrate that peat moss processing plant workers are exposed to mycobacteria in addition to other biological agents.Key words: exposure, peat moss, airborne mycobacteria.
σBand SarA independently regulate polysaccharide intercellular adhesin production inStaphylococcus epidermidis
Authors: Handke L D , Slater S R , Conlon K M , O'Donnell Sinead T , Olson M E , Bryant K A , Rupp M E , O'Gara J P , Fey P D
Published: May 2007

The production of polysaccharide intercellular adhesin (PIA) is an essential process in foreign body infections mediated by Staphylococcus epidermidis. Transcriptional regulation of the icaADBC operon, the genes responsible for production of enzymes that synthesize PIA, is multi-factorial and involves at least SarA and σB. Transcriptional and promoter fusion studies revealed that the decreased transcription of the icaADBC operon observed in a S. epidermidis 1457 sigB mutant is not mediated through a direct interaction of σB–RNA polymerase at the icaADBC promoter region but instead through the upregulation of IcaR, a known repressor of icaADBC transcription. Transcriptional analysis of a 1457 sigB–icaR double mutant confirmed that the decreased icaADBC transcript in 1457 sigB is IcaR dependent. Furthermore, primer extension studies suggest that the icaR promoter appears to be σAdependent, suggesting that σBindirectly controls icaR transcription through an unknown pathway. In addition, it was confirmed that the loss of SarA results in the loss of icaADBC transcription and PIA production in S. epidermidis. It was further demonstrated, through the over-production of SarA in 1457 sigB, that the loss of sarP1 promoter activity in 1457 sigB has little or no effect on the loss of PIA production in this mutant. Finally, it was demonstrated that PIA production could be restored in both 1457 sigB and 1457 sarA by complementing these mutants with a full-length icaADBC operon controlled by a cadmium-inducible noncognate promoter. It is concluded that σBand SarA operate independently of each other to regulate PIA production and biofilm development in S. epidermidis.Key words: Staphylococcus epidermidis, biofilm, σB, SarA, icaADBC.
Insight into heterogeneity in cell-surface hydrophobicity and ability to degrade hydrocarbons among cells of two hydrocarbon-degrading bacterial populations
Authors: Obuekwe Christian O. , Al-Jadi Zamya K. , Al-Saleh Esmaeil
Published: May 2007

The sequential bacterial adherence to hydrocarbons (BATH) of successive generations of hydrophobic fractions of Paenibacillus sp. R0032A and Burkholderia cepacia gave rise to bacterial populations of increasing cell-surface hydrophobicity. Thus, hydrophobicity of the first generation (H1) was less than that of the second generation (H2), which was less than that of the third generation (H3). Beyond H3, the hydrophobic populations became less stable and tended to lyse in hexadecane after violent (vortex) agitation, resulting in an apparent decline in BATH value. The exhaustively fractionated aqueous-phase population (L) was very hydrophilic. The overall cell-surface distribution of the population was L < parental strain < H1 < H2 < H3. The ability to degrade crude oil, hexadecane, or phenanthrene matched the degree of cell-surface hydrophobicity: L < P < H1 < H2 < H3. Thus, in natural populations of hydrocarbon-degrading Paenibacillus sp. R0032A and B. cepacia, there is a heterogeneity in the hydrophobic surface characteriistics that affects the ability of cells to use various hydrocarbon substrates.
Potential of plant extracts in combination with bacterial antagonist treatment as biocontrol agent of red rot of sugarcane
Authors: Jayakumar V. , Bhaskaran R. , Tsushima S.
Published: May 2007

Plant extracts and antifungal microorganisms were tested singly and in combination for biocontrol of sugarcane red rot disease ( Colletotrichum falcatum ) using two sugarcane ( Saccharum officinarum L.) cultivars, CoC671 and CoC92061, in pot and field experiments. Leaf extracts of Abrus precatorius and Bassia latifolia and the rhizome extract of Curcuma longa reduced Colletotrichum falcatum mycelial growth by 80%, 58%, and 57%, respectively. Although sugarcane- planting materials (setts) treated individually with either Pseudomonas fluorescens Md1 or A. precatorius in pot experiments had the lowest incidences of red rot, 20.1% and 24.2%, respectively, none of the plant extracts were effective in the field. In contrast, when the two varieties were tested separately in two field locations, the setts treated with A. precatorius in combination with a spray or soil application of P. fluorescens Md1 had the lowest incidence of red rot in both locations, e.g., 3.1% and 3.4% incidence for CoC92061 in one location, and had a similar response to the chemical control. The results suggest the applicability of plant-based extracts for the suppression of sugarcane red rot disease in the field as an environment-friendly tool in combination with antagonists.
Differential expression of Rho1GTPase and Rho3GTPase during isotropic and polarized growth of Mucor circinelloides
Authors: de la Cruz Javier O. , García-Soto Jesús , Uriostegui Citlali , Carranza Lorena , Novoa Guadalupe , Reyna Georgina , Martínez-Cadena Guadalupe
Published: May 2007

Evidence has been obtained that indicates the presence of small 22 kDa GTP-binding Rho proteins through ADP-ribosylation by Clostridium botulinum C3 exotoxin in Mucor circinelloides . Rho protein was detected at all stages of growth studied. During polarized growth, both under aerobic conditions and during the yeast–mycelia transition, the radiolabeling of the [32P]ADP-ribosylated protein increased when tube formation occurred and decreased as the hyphae branched. However, when Mucor grew isotropically, the Rho protein band was thick and its intensity did not vary significantly even after bud formation and separation of daughter cells. Crude extracts of yeast and mycelial cells exhibited a broad 22 kDa band of the [32P]ADP-ribosylated Rho protein that was resolved into a protein with a pI of 6.0, after two-dimensional electrophoresis, corresponding to the Rho1p homolog. Furthermore, [32P]ADP-ribosylated Rho protein from soluble and particulate extracts of multipolarized mycelial cells obtained from the yeast–mycelia transition was separated into two proteins with pI of 6.0 and 6.4, respectively, after two-dimensional electrophoresis. These correspond to the Rho1p and Rho3p homologs, respectively. Therefore, our results show that an increase in Rho accumulation is associated with polarized growth.
PRELIMINARY ANALYSIS OF THE PSEUDO-SOLID ECHOES OBSERVED BY NMR METHOD IN SOME POLYMERIC SAMPLES
Authors: TODICA M. , SUCIU I.
Published: May 2007

The relaxation of the transverse magnetization of the protons attached to polymeric chains and pseudo-solid echoes were observed for molten polyizobutyl and for polyizobutyl- C 7 D 8 solutions by NMR method, in a large temperature domain. The analysis of the shape of the pseudo-solid echoes leads to the possibility of evaluating the function that characterizes the contribution of the fluctuation of the entanglements to the relaxation of the transverse magnetization. The modification of this function is associated to the perturbation of the superposition property of the relaxation curves and induces changes of the properties of the pseudo-solid echoes.
NEW FINITE ELEMENT METHOD OF ELECTROMAGNETIC CALCULATION FOR COMPLEX ELECTROMAGNETIC FIELDS
Authors: LIU NIAN , XIE CHI , LIU YING , LIU LU , JIANG KE-XUN
Published: May 2007

In order to increase greatly the calculation accuracy and the computation speed for complex electromagnetic fields in modern physics, a new finite element method, which has the high computation accuracy, fast computation speed and less computer storage requirements, is presented in this paper. The new method with a high-order finite element without internal nodes is introduced to compute and analyze some complex electromagnetic fields in the electron accelerators. In this paper, the complex electromagnetic field in an electromagnetic device has been calculated successfully by the finite elements, and the electromagnetic properties of the electromagnetic device under the specific work condition is analyzed and evaluated. Good agreement is found between the computed values and the experimental values.
Early changes in rat hearts with developing pulmonary arterial hypertension can be detected with three-dimensional electrocardiography
Authors: Henkens Ivo R. , Mouchaers Koen T. B. , Vliegen Hubert W. , van der Laarse Willem J. , Swenne Cees A. , Maan Arie C. , Draisma Harmen H. M. , Schalij Ingrid , van der Wall Ernst E. , Schalij Martin J. , Vonk-Noordegraaf Anton
Published: May 2007

The study aim was to assess three-dimensional electrocardiogram (ECG) changes during development of pulmonary arterial hypertension (PAH). PAH was induced in male Wistar rats ( n = 23) using monocrotaline (MCT; 40 mg/kg sc). Untreated healthy rats served as controls ( n = 5). ECGs were recorded with an orthogonal three-lead system on days 0, 14, and 25 and analyzed with dedicated computer software. In addition, left ventricular (LV)-to-right ventricular (RV) fractional shortening ratio was determined using echocardiography. Invasively measured RV systolic pressure was 49 (SD 10) mmHg on day 14 and 64 (SD 10) mmHg on day 25 vs. 25 (SD 2) mmHg in controls (both P < 0.001). Baseline ECGs of controls and MCT rats were similar, and ECGs of controls did not change over time. In MCT rats, ECG changes were already present on day 14 but more explicit on day 25: increased RV electromotive forces decreased mean QRS-vector magnitude and changed QRS-axis orientation. Important changes in action potential duration distribution and repolarization sequence were reflected by a decreased spatial ventricular gradient magnitude and increased QRS-T spatial angle. On day 25, LV-to-RV fractional shortening ratio was increased, and RV hypertrophy was found, but not on day 14. In conclusion, developing PAH is characterized by early ECG changes preceding RV hypertrophy, whereas severe PAH is marked by profound ECG changes associated with anatomical and functional changes in the RV. Three-dimensional ECG analysis appears to be very sensitive to early changes in RV afterload.
CO2relaxes parenchyma in the liquid-filled rat lung
Authors: Emery Michael J. , Eveland Randy L. , Kim Seong S. , Hildebrandt Jacob , Swenson Erik R.
Published: May 2007

CO2regulation of lung compliance is currently explained by pH- and CO2-dependent changes in alveolar surface forces and bronchomotor tone. We hypothesized that in addition to, but independently of, those mechanisms, the parenchyma tissue responds to hypercapnia and hypocapnia by relaxing and contracting, respectively, thereby improving local matching of ventilation (V̇a) to perfusion (Q̇). Twenty adult rats were slowly ventilated with modified Krebs solution (rate = 3 min−1, 37°C, open chest) to produce unperfused living lung preparations free of intra-airway surface forces. The solution was gassed with 21% O2, balance N2, and CO2varied to produce alveolar hypocapnia (Pco2= 26.1 ± 2.4 mmHg, pH = 7.56 ± 0.04) or hypercapnia (Pco2= 55.0 ± 2.3 mmHg, pH = 7.23 ± 0.02). The results show that lung recoil, as indicated from airway pressure measured during a breathhold following a large volume inspiration, is reduced ∼30% when exposed to hypercapnia vs. hypocapnia ( P < 0.0001, paired t-test), but stress relaxation and flow-dependent airway resistance were unaltered. Increasing CO2from hypo- to hypercapnic levels caused a substantial, significant decrease in the quasi-static pressure-volume relationship, as measured after inspiration and expiration of several tidal volumes, but hysteresis was unaltered. Furthermore, addition of the glycolytic inhibitor NaF abolished CO2effects on lung recoil. The results suggest that lung parenchyma tissue relaxation, arising from active elements in response to increasing alveolar CO2, is independent of (and apparently in parallel with) passive tissue elements and may actively contribute to V̇a/Q̇ matching.
Exercise modulates platelet-nasopharyngeal carcinoma cell aggregation and subsequent tissue factor and matrix metalloproteinase activities
Authors: Wang Jong-Shyan , Chang Chuen-Ying , Chow Shu-Er , Chen Yu-Wen , Yang Chuen-Mao
Published: May 2007

Interaction between platelet and carcinoma cell contributes to pathogenesis of cancer-related thrombosis and metastasis. This study investigated whether physical exercise affects platelet-nasopharyngeal carcinoma cell (NPC) interaction and platelet-promoted tissue factor (TF) and matrix metalloproteinase (MMP) activities of NPC. Thirty sedentary men performed on three occasions moderate-intensity exercise [MIE, 60% maximal oxygen consumption (V̇o2max) for 40 min] and high-intensity exercise (HIE, up to V̇o2max), with and without warm-up exercise (WUE, 60% V̇o2maxfor 20 min) on a bicycle ergometer. Before and immediately after exercise, platelet-NPC aggregation, the TF, MMP-2 and MMP-9 expressions and activities, and TF pathway inhibitor (TFPI) and tissue inhibitor of MMP-1 levels of NPC and platelet were measured. The results of this study demonstrated that HIE enhanced platelet-NPC aggregation in the presence of fibrinogen and was accompanied by increased platelet-promoted TF activity, expression of NPC, decreased platelet-promoted MMP-2 and MMP-9 activities, and TFPI release of NPC, whereas these alterations to HIE on platelet-NPC interactions were ameliorated by WUE pretreatment. Conversely, MIE reduced the formation of platelet-NPC aggregates, but did not change the TF, TFPI, MMP-2, MMP-9, tissue inhibitor of MMP activities, and/or levels of NPC mediated by platelet. It is concluded that HIE may enhance aggregation and coagulation and reduce MMP bioactivity related to platelet-NPC interactions, by raising the binding affinity to fibrinogen and TF activity and expression and lowering TFPI release and MMP-2 and -9 activities. These effects on HIE diminish after WUE. However, MIE minimizes the risk of thrombosis induced by platelet-NPC interactions.
Mechanism of partial adaptation in airway smooth muscle after a step change in length
Authors: Ali Farah , Chin Leslie , Paré Peter D. , Seow Chun Y.
Published: May 2007

The phenomenon of length adaptation in airway smooth muscle (ASM) is well documented; however, the underlying mechanism is less clear. Evidence to date suggests that the adaptation involves reassembly of contractile filaments, leading to reconfiguration of the actin filament lattice and polymerization or depolymerization of the myosin filaments within the lattice. The time courses for these events are unknown. To gain insights into the adaptation process, we examined ASM mechanical properties and ultrastructural changes during adaptation. Step changes in length were applied to isolated bundles of ASM cells; changes in force, shortening velocity, and myosin filament mass were then quantified. A greater decrease in force was found following an acute decrease in length, compared with that of an acute increase in length. A decrease in myosin filament mass was also found with an acute decrease in length. The shortening velocity measured immediately after the length change was the same as that measured after the muscle had fully adapted to the new length. These observations can be explained by a model in which partial adaptation of the muscle leads to an intermediate state in which reconfiguration of the myofilament lattice occurred rapidly, followed by a relatively slow process of polymerization of myosin filaments within the lattice. The partially adapted intermediate state is perhaps more physiologically relevant than the fully adapted state seen under static conditions, and it simulates a more realistic behavior for ASM in vivo.
Dangerous exercise: lessons learned from dysregulated inflammatory responses to physical activity
Authors: Cooper Dan Michael , Radom-Aizik Shlomit , Schwindt Christina , Zaldivar Frank
Published: May 2007

Exercise elicits an immunological “danger” type of stress and inflammatory response that, on occasion, becomes dysregulated and detrimental to health. Examples include anaphylaxis, exercise-induced asthma, overuse syndromes, and exacerbation of intercurrent illnesses. In dangerous exercise, the normal balance between pro- and anti-inflammatory responses is upset. A possible pathophysiological mechanism is characterized by the concept of exercise modulation of previously activated leukocytes. In this model, circulating leukocytes are rendered more responsive than normal to the immune stimulus of exercise. For example, in the case of exercise anaphylaxis, food-sensitized immune cells may be relatively innocuous until they are redistributed during exercise from gut-associated circulatory depots, like the spleen, into the central circulation. In the case of asthma, the prior activation of leukocytes may be the result of genetic or environmental factors. In the case of overuse syndromes, the normally short-lived neutrophil may, because of acidosis and hypoxia, inhibit apoptosis and play a role in prolongation of inflammation rather than healing. Dangerous exercise demonstrates that the stress/inflammatory response caused by physical activity is robust and sufficiently powerful, perhaps, to alter subsequent responses. These longer term effects may occur through as yet unexplored mechanisms of immune “tolerance” and/or by a training-associated reduction in the innate immune response to brief exercise. A better understanding of sometimes failed homeostatic physiological systems can lead to new insights with significant implication for clinical translation.
Heme Oxygenase-1 Expression in Macrophages Plays a Beneficial Role in Atherosclerosis
Authors: Orozco Luz D. , Kapturczak Matthias H. , Barajas Berenice , Wang Xuping , Weinstein Michael M. , Wong Jack , Deshane Jessy , Bolisetty Subhashini , Shaposhnik Zory , Shih Diana M. , Agarwal Anupam , Lusis Aldons J. , Araujo Jesus A.
Published: May 2007

Heme oxygenase (HO-1) is the rate-limiting enzyme in the catabolism of heme, which leads to the generation of biliverdin, iron, and carbon monoxide. It has been shown to have important antioxidant and antiinflammatory properties that result in a vascular antiatherogenic effect. To determine whether HO-1 expression in macrophages constitutes a significant component of the protective role in atherosclerosis, we evaluated the effect of decreased or absent HO-1 expression in peritoneal macrophages on oxidative stress and inflammation in vitro, and the effect of complete deficiency of HO-1 expression in macrophages in atherosclerotic lesion formation in vivo. We found that compared with HO-1+/+controls, peritoneal macrophages from HO-1−/−and HO-1+/−mice exhibited (1) increased reactive oxygen species (ROS) generation, (2) increased proinflammatory cytokines such as monocyte chemotactic protein 1 (MCP-1) and interleukin 6 (IL-6), and (3) increased foam cell formation when treated with oxLDL, attributable in part to increased expression of scavenger receptor A (SR-A). Bone marrow transplantation experiments performed in lethally irradiated LDL-R null female mice, reconstituted with bone marrow from HO-1−/−versus HO-1+/+mice, revealed that HO-1−/−reconstituted animals exhibited atherosclerotic lesions with a greater macrophage content as evaluated by immunohistochemistry and planimetric assessment. We conclude that HO-1 expression in macrophages constitutes an important component of the antiatherogenic effect by increasing antioxidant protection and decreasing the inflammatory component of atherosclerotic lesions.
Substance P Targets Sympathetic Control Neurons in the Paraventricular Nucleus
Authors: Womack Matthew D. , Morris Richard , Gent Thomas C. , Barrett-Jolley Richard
Published: May 2007

The paraventricular nucleus (PVN) contains spinally-projecting neurons implicated in fine-tuning the cardiovascular system. In vivo activity of “presympathetic” parvocellular neurons is suppressed by tonic inhibition from GABA-ergic inputs, inhibition of which increases sympathetic pressor activity and heart rate. Targeting of this specific neuronal population could potentially limit elevations of heart rate and blood pressure associated with disease. Here we show, for the first time, that “presympathetic” PVN neurons are disinhibited by the neuropeptide substance P (SP) acting via tachykinin NK1 receptor inhibition of GABAAcurrents. Application of SP to the paraventricular nucleus of rats increases heart rate and blood pressure. In in vitro brain slice experiments, in the presence of GABA, 1μmol/L SP increased action current frequency by a factor of 2.7±0.6 (n=5,P≤0.05, ANOVA). Furthermore, 1μmol/L SP inhibited GABAAcurrents by 70±8% (n=8,P≤0.005 pairedttest). These effects were abolished by NK1 antagonists, but not NK2 and NK3 antagonists. GABAAinhibition was not reproduced by NK2 or NK3 agonists. The inhibition of parvocellular GABAAcurrents by SP was also abolished by a protein kinase C (PKC) inhibitor peptide and mimicked by application of phorbol-12-myristate-13-acetate (PMA), implicating a PKC-dependent mechanism. Single-channel analysis indicates that SP acts through reduction of channel mean open-time (cmot): GABAAcmotbeing reduced by approximately 60% by SP (P≤0.05 ANOVA, Bonferroni). These data suggest that tachykinins mediate their pressor activity by increasing the excitability of spinally-projecting neurons and identifies NK1 receptors as potential targets for therapeutic modulation of the cardiovascular system.
Maternal and Infant Characteristics Associated With Perinatal Arterial Stroke in the Preterm Infant
Authors: Benders Manon J.N.L. , Groenendaal Floris , Uiterwaal Cuno S.P.M. , Nikkels Peter G.J. , Bruinse Hein W. , Nievelstein Rutger A.J. , de Vries Linda S.
Published: May 2007

Background and Purpose—

Most perinatal arterial stroke (PAS) studies that investigated infant characteristics have excluded preterm infants from the study population. We sought to analyze the imaging findings and antenatal and perinatal risk factors in preterm infants with PAS.

Methods—

This was a hospital-based, case-control study of preterm infants. Case infants were confirmed by reviewing brain imaging scans and medical records (n=31). Three controls per case were individually matched with case infants from the study population.

Results—

Gestational age ranged between 27 and 36 weeks, and birth weight ranged between 580 and 3180 g. PAS was more common on the left side (61%), and 7% had bilateral PAS. The majority of strokes involved the middle cerebral artery distribution. Involvement of 1 or more lenticulostriate branches was most common among infants with a gestational age of 28 to 32 weeks, but main branch involvement was seen only in those with a gestational age of >32 weeks. Twin-to-twin-transfusion syndrome, fetal heart rate abnormality, and hypoglycemia were identified as independent risk factors for PAS.

Conclusions—

Preterm PAS is associated with prenatal, perinatal, and postpartum risk factors. We were unable to identify any maternal risk factors. Involvement of the different branches of the middle cerebral artery changed with an increase in gestational age.
Evaluation of the Clinical–Diffusion and Perfusion–Diffusion Mismatch Models in DEFUSE
Authors: Lansberg Maarten G. , Thijs Vincent N. , Hamilton Scott , Schlaug Gottfried , Bammer Roland , Kemp Stephanie , Albers Gregory W.
Published: May 2007

Background and Purpose—

The perfusion–diffusion mismatch (PDM) model has been proposed as a tool to select acute stroke patients who are most likely to benefit from reperfusion therapy. The clinical–diffusion mismatch (CDM) model is an alternative method that is technically less challenging because it does not require perfusion-weighted imaging. This study is an evaluation of these 2 models in the DEFUSE dataset.

Methods—

DEFUSE is an open-label multicenter study in which acute stroke patients were treated with intravenous tPA between 3 and 6 hours after symptoms onset and an MRI was obtained before and 3 to 6 hours after treatment. Presence of PDM and CDM was determined for each patient.

Results—

Based on conventional predefined mismatch criteria, PDM was present in 54% of the DEFUSE population and CDM in 62%. There was no agreement beyond chance between the 2 mismatch models (kappa 0.07). The presence of PDM was associated with an increased chance of favorable clinical response after reperfusion (OR, 5.4;
P
=0.039). Reperfusion was not associated with a significant increase in the rate of favorable clinical response in patients with CDM (OR, 2.2;
P
=0.34). Using optimized mismatch criteria, determined retrospectively based on DEFUSE data, the OR for favorable clinical response was 70 (
P
=0.001) for PDM and 5.1 (
P
=0.066) for CDM.

Conclusion—

The PDM model appears to be more accurate than the CDM model for selecting patients who are likely to benefit from reperfusion therapy in the 3- to 6-hour time window.
Resource Consumption of New Urban Construction in China
Authors: Fernández John E.
Published: May 2007

The volume of China's recent additions to its urban‐built environment is unprecedented. China now accounts for half of all new building area in the world. Increases in building stocks of all types have occurred during an extended period of accelerated growth of the national economy. This expansion promises to continue through 2030. As a result, the rapid conversion of land from low‐density agricultural and light manufacturing to new urban zones of high density and material‐intensive commercial and residential buildings has consumed enormous quantities of domestic and imported resources and has irreversibly altered the Chinese landscape. This article examines the consumption of material resources dedicated to Chinese building construction through a survey and analysis of the material intensity of three major building types. This provides a basis for outlining the emerging life‐cycle issues of recent additions to the built environment and of continued construction. With this as the starting point, the field of industrial ecology can work toward formulating strategies for a circular economy that include a resource‐efficient urban China.
Role of Antecedent Land Surface Conditions in Warm Season Precipitation over Northwestern Mexico
Authors: Zhu Chunmei , Cavazos Tereza , Lettenmaier Dennis P.
Published: May 2007

The role of antecedent land surface conditions including precipitation (P), surface skin temperature (Ts), soil moisture (Sm), and snow water equivalent (SWE) anomalies on the onset and intensity of the monsoon during the 1950–99 period in the core of the North American monsoon system (NAMS) region in northwestern Mexico (termed MSa here) is explored. A statistically significant positive relationship is found between monsoon onset date in MSa and previous winter precipitation in the southwestern United States (SW) and northwestern (NW) Mexico, and winter SWE in the southern Rocky Mountains. The linkages are strong during the 1960s–80s and weak otherwise, which is a much shorter period than had been found previously for an SW target area termed monsoon west (MW). In the MW study, the following land surface feedback hypothesis was proposed: more winter P and SWE lead to more spring Sm, hence lower spring and early summer Ts, which induce a weaker onset of the NAMS. This hypothesis broke down in MW due to the small contribution of land surface memory to surface thermal condition, and hence to monsoon strength. The same hypothesis is in this work for MSa by examining three links. First, it is found that in May not only the total column, but also the near-surface Sm, in both SW and NW Mexico have memory from the previous winter precipitation. The spring Sm anomalies correlate negatively with Ts anomalies over most of the continental United States and Mexico except for the desert region of SW and NW Mexico. The monsoon onset is negatively correlated with May Ts over an area roughly consisting of New Mexico and some adjacent areas, suggesting that antecedent land surface conditions may influence the premonsoon surface thermal condition, which then affects monsoon onset. The monsoon-driving force concept that states that the strength of the monsoon should be related to premonsoon land–sea surface temperature contrasts is also confirmed. The confirmation of this concept shows that late monsoon years are associated with colder land and warmer adjacent ocean than early monsoon years. In addition to the apparent land surface feedback, a strong positive relationship between May Ts anomalies and the large-scale midtropospheric circulation (Z500) anomalies is found, which suggests that large-scale circulation may play a strong (possibly more important than land feedback) role in modulating the monsoon onset.