bluuebunny/crossref_metadata_2025 huggingface dataset:
Anaerobic Degradation of
p
-Ethylphenol by “
Aromatoleum aromaticum
” Strain EbN1: Pathway, Regulation, and Involved Proteins
Authors: Wöhlbrand Lars , Wilkes Heinz , Halder Thomas , Rabus Ralf
Published: June 2008

The denitrifying “
Aromatoleum aromaticum
” strain EbN1 was demonstrated to utilize
p
-ethylphenol under anoxic conditions and was suggested to employ a degradation pathway which is reminiscent of known anaerobic ethylbenzene degradation in the same bacterium: initial hydroxylation of
p
-ethylphenol to 1-(4-hydroxyphenyl)-ethanol followed by dehydrogenation to
p
-hydroxyacetophenone. Possibly, subsequent carboxylation and thiolytic cleavage yield
p
-hydroxybenzoyl-coenzyme A (CoA), which is channeled into the central benzoyl-CoA pathway. Substrate-specific formation of three of the four proposed intermediates was confirmed by gas chromatographic-mass spectrometric analysis and also by applying deuterated
p
-ethylphenol. Proteins suggested to be involved in this degradation pathway are encoded in a single large operon-like structure (∼15 kb). Among them are a
p
-cresol methylhydroxylase-like protein (PchCF), two predicted alcohol dehydrogenases (ChnA and EbA309), a biotin-dependent carboxylase (XccABC), and a thiolase (TioL). Proteomic analysis (two-dimensional difference gel electrophoresis) revealed their specific and coordinated upregulation in cells adapted to anaerobic growth with
p
-ethylphenol and
p
-hydroxyacetophenone (e.g., PchF up to 29-fold). Coregulated proteins of currently unknown function (e.g., EbA329) are possibly involved in
p
-ethylphenol- and
p
-hydroxyacetophenone-specific solvent stress responses and related to other aromatic solvent-induced proteins of strain EbN1.
Effects of pH and Temperature on the Composition of Polar Lipids in
Thermoplasma acidophilum
HO-62
Authors: Shimada Haruo , Nemoto Naoki , Shida Yasuo , Oshima Tairo , Yamagishi Akihiko
Published: June 2008

Thermoplasma acidophilum
HO-62 was grown at different pHs and temperatures, and its polar lipid compositions were determined. Although the number of cyclopentane rings in the caldarchaeol moiety increased when
T. acidophilum
was cultured at high temperature, the number decreased at low pHs. Glycolipids, phosphoglycolipids, and phospholipids were analyzed by high-performance liquid chromatography with an evaporative light-scattering detector. The amount of caldarchaeol with more than two sugar units on one side increased under low-pH and high-temperature conditions. The amounts of glycolipids increased and those of phosphoglycolipids decreased under these conditions. The proton permeability of the liposomes obtained from the phosphoglycolipids that contained two or more sugar units was lower than that of the liposomes obtained from the phosphoglycolipids that contained one sugar unit. From these results, we propose the hypothesis that
T. acidophilum
adapts to low pHs and high temperatures by extending sugar chains on their cell surfaces, as well as by varying the number of cyclopentane rings.
Identification of a Putative Acetyltransferase Gene, MMP0350, Which Affects Proper Assembly of both Flagella and Pili in the ArchaeonMethanococcus maripaludis
Authors: VanDyke David J. , Wu John , Ng Sandy Y. M. , Kanbe Masaomi , Chaban Bonnie , Aizawa Shin-Ichi , Jarrell Ken F.
Published: June 2008

Glycosylation is a posttranslational modification utilized in all three domains of life. Compared to eukaryotic and bacterial systems, knowledge of the archaeal processes involved in glycosylation is limited. Recently,Methanococcus voltaeflagellin proteins were found to have an N-linked trisaccharide necessary for proper flagellum assembly. Current analysis by mass spectrometry ofMethanococcus maripaludisflagellin proteins also indicated the attachment of an N-glycan containing acetylated sugars. To identify genes involved in sugar biosynthesis inM. maripaludis, a putative acetyltransferase was targeted for in-frame deletion. Deletion of this gene (MMP0350) resulted in a flagellin molecular mass shift to a size comparable to that expected for underglycosylated or completely nonglycoslyated flagellins, as determined by immunoblotting. Assembled flagellar filaments were not observed by electron microscopy. Interestingly, the deletion also resulted in defective pilus anchoring. Mutant cells with a deletion of MMP0350 had very few, if any, pili attached to the cell surface compared to a nonflagellated but piliated strain. However, pili were obtained from culture supernatants of this strain, indicating that the defect was not in pilus assembly but in stable attachment to the cell surface. Complementation of MMP0350 on a plasmid restored pilus attachment, but it was unable to restore flagellation, likely because the mutant ceased to make detectable flagellin. These findings represent the first report of a biosynthetic gene involved in flagellin glycosylation in archaea. Also, it is the first gene to be associated with pili, linking flagellum and pilus structure and assembly through posttranslational modifications.
TheBradyrhizobium japonicumIrr Protein Is a Transcriptional Repressor with High-Affinity DNA-Binding Activity
Authors: Sangwan Indu , Small Sandra K. , O'Brian Mark R.
Published: June 2008

The Irr protein is a global regulator of iron homeostasis inBradyrhizobium japonicum, and a subset of genes within the Irr regulon are negatively controlled under iron limitation. However, repressor function, high-affinity DNA binding in vitro, or promoter occupancy in vivo of Irr for a negatively regulated gene has not been demonstrated. Here, we show that the blr7895 and bll6680 genes are negatively regulated by Irr as determined by derepression of transcript levels in iron-limited cells of anirrmutant strain. Electrophoretic gel mobility shift analysis showed that a component in extracts of wild-type cells grown under iron limitation bound the iron control elements (ICE) within the promoters of blr7895 and bll6680 identified previously (G. Rudolph, G. Semini, F. Hauser, A. Lindemann, M. Friberg, H. Hennecke, and H. M. Fischer, J. Bacteriol. 188:733-744, 2006). Binding was not observed with extracts of cells from the parent strain grown under high iron conditions or with those from anirrmutant. Furthermore, gel mobility supershift experiments identified Irr as a component of the binding complex. Purified recombinant Irr bound to ICE DNA with high affinity in the presence of divalent metal, withKdvalues of 7 to 19 nM, consistent with a physiological role for Irr as a transcriptional regulator. In addition, in vitro transcription initiated from the blr7895 promoter was inhibited by Irr. Whole-cell cross-linking and immunoprecipitation experiments showed that Irr occupies the promoters of blr7895 and bll6680 in vivo in an iron-dependent manner. The findings demonstrate that Irr is a transcriptional repressor that binds DNA with high affinity.
Autoregulation of AbsB (RNase III) Expression in
Streptomyces coelicolor
by Endoribonucleolytic Cleavage of
absB
Operon Transcripts
Authors: Xu Weijing , Huang Jianqiang , Cohen Stanley N.
Published: June 2008

The
Streptomyces coelicolor absB
gene encodes an RNase III family endoribonuclease and is normally essential for antibiotic biosynthesis. Here we report that AbsB controls its own expression by sequentially and site specifically cleaving stem-loop segments of its polycistronic transcript. Our results demonstrate a ribonucleolytic regulatory role for AbsB in vivo.
Genome Sequence of the Chemolithoautotrophic Bacterium
Oligotropha carboxidovorans
OM5
T
Authors: Paul Debarati , Bridges Susan , Burgess Shane C. , Dandass Yoginder , Lawrence Mark L.
Published: June 2008

Oligotropha carboxidovorans
OM5
T
(DSM 1227, ATCC 49405) is a chemolithoautotrophic bacterium with the capability to utilize carbon monoxide, carbon dioxide, and hydrogen. It is also capable of heterotrophic growth under appropriate environmental conditions. Here we report the annotated genome sequence of the circular chromosome of this organism.
Identification of Genes Involved in Inversion of Stereochemistry of a C-12 Hydroxyl Group in the Catabolism of Cholic Acid by
Comamonas testosteroni
TA441
Authors: Horinouchi Masae , Hayashi Toshiaki , Koshino Hiroyuki , Malon Michal , Yamamoto Takako , Kudo Toshiaki
Published: June 2008

Comamonas testosteroni
TA441 degrades steroids such as testosterone via aromatization of the A ring, followed by
meta
-cleavage of the ring. In the DNA region upstream of the
meta
-cleavage enzyme gene
tesB
, two genes required during cholic acid degradation for the inversion of an α-oriented hydroxyl group on C-12 were identified. A dehydrogenase, SteA, converts 7α,12α-dihydroxyandrosta-1,4-diene-3,17-dione to 7α-hydroxyandrosta-1,4-diene-3,12,17-trione, and a hydrogenase, SteB, converts the latter to 7α,12β-dihydroxyandrosta-1,4-diene-3,17-dione. Both enzymes are members of the short-chain dehydrogenase/reductase superfamily. The transformation of 7α,12α-dihydroxyandrosta-1,4-diene-3,17-dione to 7α,12β-dihydroxyandrosta-1,4-diene-3,17-dione is carried out far more effectively when both SteA and SteB are involved together. These two enzymes are encoded by two adjacent genes and are presumed to be expressed together. Inversion of the hydroxyl group at C-12 is indispensable for the subsequent effective B-ring cleavage of the androstane compound. In addition to the compounds already mentioned, 12α-hydroxyandrosta-1,4,6-triene-3,17-dione and 12β-hydroxyandrosta-1,4,6-triene-3,17-dione were identified as minor intermediate compounds in cholic acid degradation by
C. testosteroni
TA441.
Vo2requirement at different displayed power outputs on five cycle ergometer models: a preliminary study
Authors: Guiraud T , Léger L , Long A , Thébault N , Tremblay J , Passelergue P
Published: June 2008

Background and aims

The validity of five brands of cycle ergometers was evaluated by the comparison of the Vo2requirements at different displayed power.

Methods and results

Five physically active men performed a continuous incremental exercise test on five ergometers (Ergomeca, Lifecycle, Monark, Polar S710 and CompuTrainer). The latter was also compared with a standard dynamometer in order to associate Vo2values with the real power. Every test started with a 5-min warm-up on the same cycle ergometer (Ergomeca) at 100 W to make sure that the Vo2differences do not come from Vo2measurement error. Only last minute steady-state Vo2values of each 2-min stage were used for the Vo2–watt curve. Large differences (5– 10 ml kg−1min−1) at the same displayed power indicate inaccuracy of displayed power output (PO). Using corrected power values from the dynamometer revealed that for the same Vo2the CompuTrainer underestimates PO by ∼30 W between 100 and 300 W, whereas the Lifecycle overestimate it by 3–53 W from 100 to 300 W. The Monark and Polar S710 underestimate PO by 15 W and the Ergomeca by ∼5 W.

Conclusion

Inaccuracies between −10% and 18% in displayed PO of various cycle ergometers question their interchangeability.
Analysing the protective potential of padded soccer goalkeeper shorts
Authors: Schmitt K U , Nusser M , Derler S , Boesiger P
Published: June 2008

Objective

In this study, the potential of currently available padded soccer goalkeeper shorts to prevent hip injuries sustained in side jumps was investigated.

Design

Within the scope of this study, a survey among professional and amateur goalkeepers, trainers and the medical staff was performed. In addition, commercially available shorts were impact-tested using an artificial hip model. The results were compared with requirements established for hip protectors for elderly.

Results

The results of the survey found that contusions and abrasions were observed most often for all players. Fractures and arthritis were only reported by amateur players, whereas bursitis was more frequently observed by professional players. Amateurs have a significantly higher risk of injury than professional players, and the higher injury risk during training is significantly higher compared with the injury risk during a match. No difference of the injury risk was found between goalkeepers wearing padded shorts and those who did not.

Impact tests indicated a wide range of performance of the currently available products. The padded shorts generally reduce impact forces, but mostly perform poorly. Only shorts that were made of visco-elastic foam fulfilled the basic requirements requested for hip protectors for elderly.

Conclusions

The quality of most of the currently available goalkeeper shorts needs to be improved to effectively prevent hip injury sustained in side jumps.
Ad libitum adjustments to fluid intake during cool environmental conditions maintain hydration status during a 3-day mountain bike race
Authors: Rose S , Peters-Futre E M
Published: June 2008

Objective

In this study, the hydration status of amateur cyclists who voluntarily adjusted their fluid intake to environmental conditions during a 3-day, 248-km mountain bike (MTB) race was assessed.

Design

Prospective observational field study.

Setting

Sani2C MTB Race, KwaZulu-Natal, South Africa, 2006.

Participants

18 randomly selected amateur, male MTB cyclists.

Main outcome measures

Reported usual fluid intake, environmental conditions, voluntary fluid intake, urine voided, changes in body mass, serum osmolality (SO), sodium concentration [Na+] and urinary specific gravity (Usg) during each stage (S).

Results

Dry bulb temperature (adjusted for windchill) ranged from 6° to 21.4°C during S1, S2 and S3. While 77.8% (n = 14) of subjects reported a usual intake of >750 ml h−1in previous MTB events, mean (SE) fluid intake in this race ranged from 341 (32) ml h−1during S1 to 551 (56) ml h−1during S3. Changes in mean body mass ranged between −0.99% and −2.02% during the three stages. Mean SO and serum [Na+] ranged between 292 (0.73) mOsm kg−1and 298 mOsm kg−1and 137 (0.35) mEq and 140 (0.42) mEq, respectively, during the 3-day period, while Usg remained ≤1.025.

Conclusion

Ad libitum fluid intake during the 2006 Sani2C MTB Race, which took place in unexpectedly cold environmental conditions, was substantially lower than the usual reported fluid intake of subjects. Changes in body mass, SO, serum [Na+] and Usg were not clinically significant, indicating that an adequate hydration status was maintained during the multiday MTB cycle race.
Differential proinflammatory and prooxidant effects of bone morphogenetic protein-4 in coronary and pulmonary arterial endothelial cells
Authors: Csiszar Anna , Labinskyy Nazar , Jo Hanjoong , Ballabh Praveen , Ungvari Zoltan
Published: June 2008

There is increasing evidence that TGF-β family member cytokine bone morphogenetic protein (BMP)-4 plays different pathophysiological roles in the pulmonary and systemic circulation. Upregulation of BMP-4 has been linked to atherosclerosis and hypertension in the systemic circulation, whereas disruption of BMP-4 signaling is associated with the development of pulmonary hypertension. To test the hypothesis that BMP-4 elicits differential effects in the pulmonary and systemic circulation, we compared the prooxidant and proinflammatory effects of BMP-4 in cultured human coronary arterial endothelial cells (CAECs) and pulmonary arterial endothelial cells (PAECs). We found that BMP-4 (from 0.3 to 10 ng/ml) in CAECs increased O2•− and H2O2 generation, induced NF-κB activation, upregulated ICAM-1, and induced monocyte adhesiveness to ECs. In contrast, BMP-4 failed to induce oxidative stress or endothelial activation in PAECs. Also, BMP-4 treatment impaired acetylcholine-induced relaxation and increased O2•− production in cultured rat carotid arteries, whereas cultured rat pulmonary arteries were protected from these adverse effects of BMP-4. Thus, we propose that BMP-4 exerts prooxidant, prohypertensive, and proinflammatory effects only in the systemic circulation, whereas pulmonary arteries are protected from these adverse effects of BMP-4. The vascular bed-specific endothelial effects of BMP-4 are likely to contribute to its differential pathophysiological role in the systemic and pulmonary circulation.
Nonlinear coupling is absent in acute myocardial patients but not healthy subjects
Authors: Bai Yan , Siu Kin L. , Ashraf Salman , Faes Luca , Nollo Giandomenico , Chon Ki H.
Published: June 2008

We investigated whether autonomic nervous system imbalance imposed by pharmacological blockades and associated with acute myocardial infarction (AMI) is manifested as modifications of the nonlinear interactions in heart rate variability signal using a statistically based bispectrum method. The statistically based bispectrum method is an ideal approach for identifying nonlinear couplings in a system and overcomes the previous limitation of determining in an ad hoc way the presence of such interactions. Using the improved bispectrum method, we found significant nonlinear interactions in healthy young subjects, which were abolished by the administration of atropine but were still present after propranolol administration. The complete decoupling of nonlinear interactions was obtained with double pharmacological blockades. Nonlinear couplings were found to be the strongest for healthy young subjects followed by degradation with old age and a complete absence of such couplings for the old age-matched AMI subjects. Our results suggest that the presence of nonlinear couplings is largely driven by the parasympathetic nervous system regulation and that the often-reported autonomic nervous system imbalance seen in AMI subjects is manifested as the absence of nonlinear interactions between the sympathetic and parasympathetic nervous regulations.
Myocardial expression, signaling, and function of GPR22: a protective role for an orphan G protein-coupled receptor
Authors: Adams John W. , Wang Jianming , Davis James R. , Liaw Chen , Gaidarov Ibragim , Gatlin Joel , Dalton Nancy D. , Gu Yusu , Ross John , Behan Dominic , Chien Ken , Connolly Daniel
Published: June 2008

G protein-coupled receptors (GPCRs) play an essential role in the regulation of cardiovascular function. Therapeutic modulation of GPCRs has proven to be beneficial in the treatment of human heart disease. Myocardial “orphan” GPCRs, for which the natural ligand is unknown, represent potential novel therapeutic targets for the treatment of heart disease. Here, we describe the expression pattern, signaling pathways, and possible physiological role of the orphan GPR22. GPR22 mRNA analysis revealed a highly restricted expression pattern, with remarkably abundant and selective expression in the brain and heart of humans and rodents. In the heart, GPR22 mRNA was determined to be expressed in all chambers and was comparable with transcript levels of the β1-adrenergic receptor as assessed by Taqman PCR. GPR22 protein expression in cardiac myocytes and coronary arteries was demonstrated in the rat heart by immunohistochemistry. When transfected into HEK-293 cells, GPR22 coupled constitutively to Gi/Go, resulting in the inhibition of adenyl cyclase. No constitutive coupling to Gsor Gqwas observed. Myocardial mRNA expression of GPR22 was dramatically reduced following aortic banding in mice, suggesting a possible role in response to the stress associated with increased afterload. The absence of detectable GPR22 mRNA expression in the hearts of GPR22−/−mice had no apparent effect on normal heart structure or function; however, these mice displayed increased susceptibility to functional decompensation following aortic banding. Thus, we described, for the first time, the expression pattern and signaling for GPR22 and identified a protective role for GPR22 in response to hemodynamic stress resulting from increased afterload.
Heme proteins mediate the conversion of nitrite to nitric oxide in the vascular wall
Authors: Alzawahra Wael F. , Talukder M. A. Hassan , Liu Xiaoping , Samouilov Alexandre , Zweier Jay L.
Published: June 2008

Nitric oxide (NO) has been shown to be the endothelium-derived relaxing factor (EDRF), and its impairment contributes to a variety of cardiovascular disorders. Recently, it has been recognized that nitrite can be an important source of NO; however, questions remain regarding the activity and mechanisms of nitrite bioactivation in vessels and its physiological importance. Therefore, we investigated the effects of nitrite on in vivo hemodynamics in rats and in vitro vasorelaxation in isolated rat aorta under aerobic conditions. Studies were performed to determine the mechanisms by which nitrite is converted to NO. In anesthetized rats, nitrite dose dependently decreased both systolic and diastolic blood pressure with a threshold dose of 10 μM. Similarly, nitrite (10 μM-2 mM) caused vasorelaxation of aortic rings, and NO was shown to be the intermediate factor responsible for this activity. With the use of electrochemical as well as electron paramagnetic resonance (EPR) spectroscopy techniques NO generation was measured from isolated aortic vessels following nitrite treatment. Reduction of nitrite to NO was blocked by heating the vessel, suggesting that an enzymatic process is involved. Organ chamber experiments demonstrated that aortic relaxation induced by nitrite could be blocked by both hemoglobin and soluble guanylyl cyclase (sGC) inhibitor 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one (ODQ). In addition, both electrochemical and EPR spin-trapping measurements showed that ODQ inhibits nitrite-mediated NO production. These findings thus suggest that nitrite can be a precursor of EDRF and that sGC or other heme proteins inhibited by ODQ catalyze the reduction of nitrite to NO.
Heat stress activates AKT via focal adhesion kinase-mediated pathway in neonatal rat ventricular myocytes
Authors: Wei Hongguang , Vander Heide Richard S.
Published: June 2008

Heat stress (HS)-induced cardioprotection is associated with increased paxillin localization to the membrane fraction of neonatal rat ventricular myocytes (NRVM). The purpose of this study was 1) to examine the subcellular signaling pathways activated by HS; 2) to determine whether myocardial stress organizes and activates an integrated survival pathway; and 3) to investigate potential downstream cytoprotective proteins activated by HS. After HS, NRVM were subjected to chemical inhibitors (CI) designed to simulate ischemia by inhibiting both glycolysis and mitochondrial respiration. Protein kinase B (AKT) expression (wild type) was increased selectively with an adenoviral vector. Cell signaling was analyzed with Western blot analysis, while oncosis/apoptosis was assayed by measuring Trypan blue exclusion and/or terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, respectively. HS increased phosphorylation of focal adhesion kinase (FAK) at tyrosine 397 but did not adversely affect the viability of NRVM before CI. HS increased association between FAK and phosphatidylinositol 3-kinase as well as causing a significant increase in AKT activity. Increased expression of wild-type AKT protected myocytes from both oncotic and apoptotic cell death. Increased expression of a FAK inhibitor, FRNK, reduced AKT phosphorylation in response to HS both at time 0 and after 10 min of CI compared with myocytes expressing empty virus. We conclude that myocardial stress activates cytoskeleton-based signaling pathways that are associated with protection from lethal cell injury.
AGE/RAGE produces endothelial dysfunction in coronary arterioles in Type 2 diabetic mice
Authors: Gao Xue , Zhang Hanrui , Schmidt Ann Marie , Zhang Cuihua
Published: June 2008

We hypothesized that impaired nitric oxide (NO)-dependent dilation (endothelial dysfunction) in Type 2 diabetes results, in part, from elevated production of superoxide (O2•−) induced by the interaction of advanced glycation end products (AGE)/receptor for AGE (RAGE) and TNF-α signaling. We assessed the role of AGE/RAGE and TNF-α signaling in endothelial dysfunction in Type 2 diabetic (Leprdb) mice by evaluation of endothelial function in isolated coronary resistance vessels of normal control (nondiabetic, m Leprdb) and diabetic mice. Although dilation of vessels to the endothelium-independent vasodilator sodium nitroprusside (SNP) was not different between diabetic and control mice, dilation to the endothelium-dependent agonist acetylcholine (ACh) was reduced in diabetic vs. control mice. The activation of RAGE with RAGE agonist S100b eliminated SNP-potentiated dilation to ACh in Leprdbmice. Administration of a soluble form of RAGE (sRAGE) partially restored dilation in diabetic mice but did not affect dilation in control mice. The expression of RAGE in coronary arterioles was markedly increased in diabetic vs. control mice. We also observed in diabetic mice that augmented RAGE signaling augmented expression of TNF-α, because this increase was attenuated by sRAGE or NF-κB inhibitor MG132. Protein and mRNA expression of NAD(P)H oxidase subunits including NOX-2, p22phox, and p40phoxincreased in diabetic compared with control mice. sRAGE significantly inhibited the expression of NAD(P)H oxidase in diabetic mice. These results indicate that AGE/RAGE signaling plays a pivotal role in regulating the production/expression of TNF-α, oxidative stress, and endothelial dysfunction in Type 2 diabetes.
Ventilatory, hemodynamic, sympathetic nervous system, and vascular reactivity changes after recurrent nocturnal sustained hypoxia in humans
Authors: Gilmartin Geoffrey S. , Tamisier Renaud , Curley Matthew , Weiss J. Woodrow
Published: June 2008

Recurrent and intermittent nocturnal hypoxia is characteristic of several diseases including chronic obstructive pulmonary disease, congestive heart failure, obesity-hypoventilation syndrome, and obstructive sleep apnea. The contribution of hypoxia to cardiovascular morbidity and mortality in these disease states is unclear, however. To investigate the impact of recurrent nocturnal hypoxia on hemodynamics, sympathetic activity, and vascular tone we evaluated 10 normal volunteers before and after 14 nights of nocturnal sustained hypoxia (mean oxygen saturation 84.2%, 9 h/night). Over the exposure, subjects exhibited ventilatory acclimatization to hypoxia as evidenced by an increase in resting ventilation (arterial Pco2 41.8 ± 1.5 vs. 37.5 ± 1.3 mmHg, mean ± SD; P < 0.05) and in the isocapnic hypoxic ventilatory response (slope 0.49 ± 0.1 vs. 1.32 ± 0.2 l/min per 1% fall in saturation; P < 0.05). Subjects exhibited a significant increase in mean arterial pressure (86.7 ± 6.1 vs. 90.5 ± 7.6 mmHg; P < 0.001), muscle sympathetic nerve activity (20.8 ± 2.8 vs. 28.2 ± 3.3 bursts/min; P < 0.01), and forearm vascular resistance (39.6 ± 3.5 vs. 47.5 ± 4.8 mmHg·ml−1·100 g tissue·min; P < 0.05). Forearm blood flow during acute isocapnic hypoxia was increased after exposure but during selective brachial intra-arterial vascular infusion of the alpha-blocker phentolamine it was unchanged after exposure. Finally, there was a decrease in reactive hyperemia to 15 min of forearm ischemia after the hypoxic exposure. Recurrent nocturnal hypoxia thus increases sympathetic activity and alters peripheral vascular tone. These changes may contribute to the increased cardiovascular and cerebrovascular risk associated with clinical diseases that are associated with chronic recurrent hypoxia.
Modulation of lymphatic muscle contractility by the neuropeptide substance P
Authors: Davis Michael J. , Lane Megan M. , Davis Ann M. , Durtschi David , Zawieja David C. , Muthuchamy Mariappan , Gashev Anatoliy A.
Published: June 2008

Substance P (SP) is a neuropeptide associated with sensory innervation of lymphoid tissue and a suspected modulator of lymphatic function in inflammation. Only a few studies have examined the effects of SP on lymphatic contraction, and it is not clear to what extent SP acts directly on the lymphatic muscle and/or endothelium or indirectly through changes in intraluminal filling pressure secondary to increases in capillary permeability/filtration. We tested the effects of SP on the spontaneous contractions of rat isolated mesenteric lymphatic vessels under isometric and isobaric conditions, hypothesizing that low concentrations would stimulate lymphatic pumping by enhancing lymphatic muscle contraction in a manner complementary to the effect of increased preload. Under isometric conditions, SP (10 nM) dramatically enhanced lymphatic chronotropy and inotropy. Unlike guinea pig lymphatics, SP actions were not blocked by cyclooxygenase or PLA2inhibition. In the absence of SP, ramp increases in isometric preload resulted in ×∼1.6 increases in contraction amplitude (Amp) and ×∼1.7 increases in frequency (Freq). SP increased Freq by ×∼2.4, Amp by ×∼1.9, and the Amp-Freq product (AFP) by ×∼3.5. Under isobaric conditions, the pressure elevation from 0.5 to 10 cmH2O in the absence of SP decreased Amp by ×∼0.6 and increased Freq by ×∼1.8. SP caused a modest increase in Amp, a robust increase in Freq at all pressures, and shifted the AFP-pressure relationship upward and leftward. Therefore, SP has substantial positive inotropic and chronotropic effects on rat lymphatic muscle, improving pump efficiency independent of the effects of preload and broadening of the working range of the lymphatic pump.
Ectopic atrial arrhythmias arising from canine thoracic veins during in vivo stellate ganglia stimulation
Authors: Tan Alex Y. , Zhou Shengmei , Jung Byung Chun , Ogawa Masahiro , Chen Lan S. , Fishbein Michael C. , Chen Peng-Sheng
Published: June 2008

The purpose of the present study was to determine whether thoracic veins may act as ectopic pacemakers and whether nodelike cells and rich sympathetic innervation are present at the ectopic sites. We used a 1,792-electrode mapping system with 1-mm resolution to map ectopic atrial arrhythmias in eight normal dogs during in vivo right and left stellate ganglia (SG) stimulation before and after sinus node crushing. SG stimulation triggered significant elevations of transcardiac norepinephrine levels, sinus tachycardia in all dogs, and atrial tachycardia in two of eight dogs. Sinus node crushing resulted in a slow junctional rhythm (51 ± 6 beats/min). Subsequent SG stimulation induced 20 episodes of ectopic beats in seven dogs and seven episodes of pulmonary vein tachycardia in three dogs (cycle length 273 ± 35 ms, duration 16 ± 4 s). The ectopic beats arose from the pulmonary vein ( n = 11), right atrium ( n = 5), left atrium ( n = 2), and the vein of Marshall ( n = 2). There was no difference in arrhythmogenic effects of left vs. right SG stimulation (13/29 vs. 16/29 episodes, P = nonsignificant). There was a greater density of periodic acid Schiff-positive cells ( P < 0.05) and sympathetic nerves ( P < 0.05) at the ectopic sites compared with other nonectopic atrial sites. We conclude that, in the absence of a sinus node, thoracic veins may function as subsidiary pacemakers under heightened sympathetic tone, becoming the dominant sites of initiation of focal atrial arrhythmias that arise from sites with abundant sympathetic nerves and periodic acid Schiff-positive cells.
Arsenic upregulates MMP-9 and inhibits wound repair in human airway epithelial cells
Authors: Olsen Colin E. , Liguori Andrew E. , Zong Yue , Lantz R. Clark , Burgess Jefferey L. , Boitano Scott
Published: June 2008

As part of the innate immune defense, the polarized conducting lung epithelium acts as a barrier to keep particulates carried in respiration from underlying tissue. Arsenic is a metalloid toxicant that can affect the lung via inhalation or ingestion. We have recently shown that chronic exposure of mice or humans to arsenic (10–50 ppb) in drinking water alters bronchiolar lavage or sputum proteins consistent with reduced epithelial cell migration and wound repair in the airway. In this report, we used an in vitro model to examine effects of acute exposure of arsenic (15–290 ppb) on conducting airway lung epithelium. We found that arsenic at concentrations as low as 30 ppb inhibits reformation of the epithelial monolayer following scrape wounds of monolayer cultures. In an effort to understand functional contributions to epithelial wound repair altered by arsenic, we showed that acute arsenic exposure increases activity and expression of matrix metalloproteinase (MMP)-9, an important protease in lung function. Furthermore, inhibition of MMP-9 in arsenic-treated cells improved wound repair. We propose that arsenic in the airway can alter the airway epithelial barrier by restricting proper wound repair in part through the upregulation of MMP-9 by lung epithelial cells.
Atrial Septopulmonary Bundle of the Posterior Left Atrium Provides a Substrate for Atrial Fibrillation Initiation in a Model of Vagally Mediated Pulmonary Vein Tachycardia of the Structurally Normal Heart
Authors: Klos Matthew , Calvo David , Yamazaki Masatoshi , Zlochiver Sharon , Mironov Sergey , Cabrera José-Angel , Sanchez-Quintana Damian , Jalife José , Berenfeld Omer , Kalifa Jérôme
Published: June 2008

Background—

The posterior left atrium (PLA) and pulmonary veins (PVs) have been shown to be critical for atrial fibrillation (AF) initiation. However, the detailed mechanisms of reentry and AF initiation by PV impulses are poorly understood. We hypothesized that PV impulses trigger reentry and AF by undergoing wavebreaks as a result of sink-to-source mismatch at specific PV-PLA transitions along the septopulmonary bundle, where there are changes in thickness and fiber direction.

Methods and Results—

In 7 Langendorff-perfused sheep hearts AF was initiated by a burst of 6 pulses (CL 80 to 150ms) delivered to the left inferior or right superior PV ostium 100 to 150 ms after the sinus impulse in the presence of 0.5 μmol/L acetylcholine. The exposed septal-PLA endocardial area was mapped with high spatio-temporal resolution (DI-4-ANEPPS, 1000-fr/s) during AF initiation. Isochronal maps for each paced beat preceding AF onset were constructed to localize areas of conduction delay and block. Phase movies allowed the determination of the wavebreak sites at the onset of AF. Thereafter, the PLA myocardial wall thickness was quantified by echocardiography, and the fiber direction in the optical field of view was determined after peeling off the endocardium. Finally, isochrone, phase and conduction velocity maps were superimposed on the corresponding anatomic pictures for each of the 28 episodes of AF initiation. The longest delays of the paced PV impulses, as well as the first wavebreak, occurred at those boundaries along the septopulmonary bundle that showed sharp changes in fiber direction and the largest and most abrupt increase in myocardial thickness.

Conclusion—

Waves propagating from the PVs into the PLA originating from a simulated PV tachycardia triggered reentry and vagally mediated AF by breaking at boundaries along the septopulmonary bundle where abrupt changes in thickness and fiber direction resulted in sink-to-source mismatch and low safety for propagation.
Ventricular Tachycardia Ablation
Authors: Sacher Frédéric , Tedrow Usha B. , Field Michael E. , Raymond Jean-Marc , Koplan Bruce A. , Epstein Laurence M. , Stevenson William G.
Published: June 2008

Background—

Evolving management of coronary artery disease, heart failure, and the use of implantable cardioverter-defibrillators impacts the characteristics of patients with recurrent ventricular tachycardia (VT). We investigated the substrate, procedure, and outcome evolution of all patients referred for VT ablation during the past 8 years.

Methods and Results—

From 1999 to 2006, 493 consecutive patients (358 male, 57�16 years) underwent 623 VT ablations: 131 had no structural heart disease (SHD), 213 had ischemic cardiomyopathies (ICMP), and 149 had nonischemic cardiomyopathies (NICMP). Although the main substrate is ICMP, the proportion of NICMP has increased from 27% to 35% (
P
=0.06) from 1999–2002 to the 2003–2006. The procedure abolished or modified inducible VTs in ≥75% of patients in all groups, but abolition of all monomorphic VTs was achieved in 125 (83%) patients without SHD, 180 (65%) with ICMP, and 99 (51%) with NICMP (
P
<0.0001). During a mean follow-up of 3.3�2.4 years, no deaths occurred in patients without SHD, but 75 patients (35%) with ICMP and 26 patients (17%) with NICMP died after a median of 13 months. Multivariate Cox regression analysis found that age, ejection fraction, and need for preprocedural mechanical hemodynamic support predicted mortality.

Conclusions—

The substrate causing VT in patients requiring ablation is evolving and determines the long-term outcome. In the setting of a normal heart, VT ablation is associated with a low risk of subsequent mortality, with no deaths occurring during a mean follow-up of >3 years. In contrast, in patients with SHD and recurrent VT, VT ablation can be helpful to suppress drug refractory VT, but long-term mortality remains significant.
Social Influences on Self-Reported Physical Activity in Overweight Latino Children
Authors: Gesell Sabina B. , Reynolds Erica B. , Ip Edward H. , Fenlason Lindy C. , Pont Stephen J. , Poe Eli K. , Barkin Shari L.
Published: June 2008

Psychosocial variables influence physical activity for different age groups, sex, and ethnic groups. However, little is known about their influence on physical activity in preadolescent Latino children. The authors examined how a) confidence in one's ability to be physically active (self-efficacy); b) ideas about the consequences of being physically active (beliefs), and c) the influences of family and friends on physical activity (social influences) effect physical activity levels in overweight (body mass index ≥85%) Latino preadolescent children. One hundred and fourteen preadolescents participated in a larger intervention designed to improve healthy lifestyles for Latino families. The authors report baseline data collected at a community-based primary care clinic. Multivariate regression analyses showed that only social influences significantly predicted ( P < .01) the metabolic equivalent adjusted self-reported baseline physical activity. Prevention and intervention strategies that augment social influences on physical activity are likely to result in more physical activity and improved health in these children.
Severe Failure to Thrive in Infant
Authors: Allapathi Deepti , Alvarez Dora , Dave-Sharma Swati , Prosper Gerard , Sharma Jayendra
Published: June 2008

Failure to thrive in an infant has multiple etiologies and at times, is only manifestation of underlying serious disease. Bartter syndrome is a rare disease that manifests as failure to thrive. It can be diagnosed by a careful history, physical examination, and abnormal electrolyte pattern. It can be alleviated by appropriate management, whereas failure to recognize early can be life threatening. A case of severe failure to thrive in an infant due to neonatal form of Bartter syndrome, its manifestations, management, and outcome is presented in this article.
Mediating the Mediation Debate
Authors: Read Benjamin L. , Michelson Ethan
Published: June 2008

China's elaborate system of local mediation committees has piqued researchers' curiosity for decades and sparked an argument in these pages. Crucial questions—concerning how much mediation actually takes place, what kinds of disputes are mediated, who seeks mediation, and how successful it is—have gone unanswered for lack of data. This article addresses these issues using original surveys from Beijing and villages in six provinces, supplemented by participant-observation research on actual instances of mediation. We find that mediation is fairly common in the country-side while occurring in a narrow set of contexts in the city. Those who are actively involved in institutions of grassroots governance are much more likely than others to seek such remedies, and in rural China, women pursue it more than men do. Modernization may diminish the salience of this form of dispute resolution, yet it is far from extinct, even in contemporary society.
Teaching Students With Severe Speech and Physical Impairments a Decoding Strategy Using Internal Speech and Motoric Indicators
Authors: Swinehart-Jones Dawn , Heller Kathryn Wolff
Published: June 2008

Children who have severe speech and physical impairments often have difficulty acquiring literacy skills. One critical area of literacy instruction involves promoting word identification though the development of decoding strategies that can be implemented by students independently. This study investigated teaching four students who have cerebral palsy and dysarthric speech to internalize the three-step decoding strategy found in the Nonverbal Reading Approach, as demonstrated by motoric indicators (individualized motor movements that parallel the decoding steps). The results of this study indicate that students are able to learn the three-step decoding strategy with the addition of a motoric indicator to identify words in isolation, as well as to apply the strategy independently upon encountering unknown words in connected text.
Reported Prevalence of Evidence-Based Instructional Practices in Special Education
Authors: Burns Matthew K. , Ysseldyke James E.
Published: June 2008

The federal mandate for use of evidence-based practice in schools focuses attention on the frequently discussed research-to-practice gap in education. The current study examined the frequency with which evidence-based practices are engaged in the education of pupils with disabilities. In sum, 174 special education teachers and 333 school psychologists completed a 12-item survey in which they rated the frequency of various practices used in special education. Respondents reported that direct instruction is the most frequently used instructional methodology and that perceptual-motor training is the least frequent. However, some practices with little empirical support (e.g., modality instruction) are reportedly used with some frequency, and special education teachers reported using ineffective approaches (social skills training) as frequently as they did those approaches with a strong research base (applied behavior analysis). Thus, these data present some reason for optimism, although special education does not appear to be immune to a research-to-practice gap.
The Cultural/Racial Dimension of Psychotic Disorders in African American Patients
Authors: Whaley Arthur L. , Hall Brittany N.
Published: June 2008

Studies of race differences in psychotic disorders frequently show greater severity among African Americans. An intraracial or cultural analysis of psychotic symptoms was conducted to better understand the racial disparities. Specifically, cultural/racial themes in the delusions and hallucinations of a sample of 156 African American psychiatric patients were examined via content analysis. Cultural/racial themes focusing on general racial issues and racism were identified in the delusions and hallucinations of these patients. The current findings also indicated that delusions were more prevalent and contain more cultural content than hallucinations. Implications for racial differences in psychotic symptom expression are discussed.
A Conceptual Framework for Understanding the Strengths of Black Youths
Authors: Nicolas Guerda , Helms Janet E. , Jernigan Maryam M. , Sass Theresa , Skrzypek Adrienne , DeSilva Angela M.
Published: June 2008

The strengths of Black youths lie in their abilities to resist the barriers that they encounter in the various environments in which they exist. Yet the media and social science literature have defined the youths in terms of the pathology of their environments rather than focusing on the assets that Black youths use in such environments. Thus, terms such as inner city , urban , and at-risk are used as proxies for the youths' personality attributes and themes, such as violence, substance abuse, school underachievement, and family instability are used to define their life experiences. In doing so, the literature suggests that the negative behaviors that it ascribes to Black youths are normative in actuality. In this article, a new framework for understanding the assets of Black youths is provided. The framework highlights the role of racial socialization in the youths' development of strengths that allow them to cope effectively with barriers.
Knowledge and Beliefs Related to Cervical Cancer and Screening Among Korean American Women
Authors: Lee Eunice E. , Fogg Louis , Menon Usha
Published: June 2008

The purpose of this article is to examine knowledge and health beliefs associated with cervical cancer screening among Korean American women. A telephone survey was conducted with 189 Korean American women in the Chicago area. Age, marital status, income, knowledge of early detection method for cervical cancer, and perceived beliefs about benefits of and barriers to receiving Pap tests were all related to outcomes of ever having a Pap test and having had one in the preceding 3 years. Variables uniquely related to ever having a Pap test were education, employment status, fluency in English, and proportion of life spent in the United States. Variables uniquely related to having had the test during the preceding 3 years were having a usual source of care and regular checkups. Different intervention components are suggested for the groups of Korean American women who have never had a Pap smear and for those who have not had one in the preceding 3 years, in addition to common intervention strategies that aim to increase knowledge and perceived benefit and to decrease perceived barriers to receiving Pap tests.
Wind Power in Ontario
Authors: Rowlands Ian H. , Jernigan Carey
Published: June 2008

The purpose of this article is to investigate wind turbine production, the variability of that production, and the relationship between output and system-wide demand. A review of the literature reveals that a variety of measures (and methods) to explore the variability of wind power production exist. Attention then turns to the province of Ontario (Canada), and the performances of four wind farms are examined for 2006 and 2007. Key conclusions include that the wind farms' capacity factors vary from 27.6% to 35.6%, with higher values in winter as compared to summer; wind power performs better than the seasonal average during peak periods; wind is a better “partner” for the Ontario electricity system in the winter as opposed to the summer; and the increased geographic distribution of wind farms decreases their collective variability.