bluuebunny/crossref_metadata_2025 huggingface dataset:
Proximity-Dependent Inhibition in
Escherichia coli
Isolates from Cattle
Authors: Sawant Ashish A. , Casavant N. Carol , Call Douglas R. , Besser Thomas E.
Published: February 2011

We describe a novel proximity-dependent inhibition phenotype of
Escherichia coli
that is expressed when strains are cocultured in defined minimal media. When cocultures of “inhibitor” and “target” strains approached a transition between logarithmic and stationary growth, target strain populations rapidly declined >4 log CFU per ml over a 2-h period. Inhibited strains were not affected by exposure to conditioned media from inhibitor and target strain cocultures or when the inhibitor and target strains were incubated in shared media but physically separated by a 0.4-μm-pore-size membrane. There was no evidence of lytic phage or extracellular bacteriocin involvement, unless the latter was only present at effective concentrations within immediate proximity of the inhibited cells. The inhibitory activity observed in this study was effective against a diversity of
E. coli
strains, including enterohemorrhagic
E. coli
serotype O157:H7, enterotoxigenic
E. coli
expressing F5 (K99) and F4 (K88) fimbriae, multidrug-resistant
E. coli
, and commensal
E. coli.
The decline in counts of target strains in coculture averaged 4.8 log CFU/ml (95% confidence interval, 4.0 to 5.5) compared to their monoculture counts. Coculture of two inhibitor strains showed mutual immunity to inhibition. These results suggest that proximity-dependent inhibition can be used by bacteria to gain a numerical advantage when populations are entering stationary phase, thus setting the stage for a competitive advantage when growth conditions improve.
Traffic of Chitin Synthase 1 (CHS-1) to the Spitzenkörper and Developing Septa in Hyphae of Neurospora crassa: Actin Dependence and Evidence of Distinct Microvesicle Populations
Authors: Sánchez-León Eddy , Verdín Jorge , Freitag Michael , Roberson Robert W. , Bartnicki-Garcia Salomon , Riquelme Meritxell
Published: February 2011

We describe the subcellular location of chitin synthase 1 (CHS-1), one of seven chitin synthases in
Neurospora crassa
. Laser scanning confocal microscopy of growing hyphae showed CHS-1–green fluorescent protein (GFP) localized conspicuously in regions of active wall synthesis, namely, the core of the Spitzenkörper (Spk), the apical cell surface, and developing septa. It was also present in numerous fine particles throughout the cytoplasm plus some large vacuoles in distal hyphal regions. Although the same general subcellular distribution was observed previously for CHS-3 and CHS-6, they did not fully colocalize. Dual labeling showed that the three different chitin synthases were contained in different vesicular compartments, suggesting the existence of a different subpopulation of chitosomes for each CHS. CHS-1–GFP persisted in the Spk during hyphal elongation but disappeared from the septum after its development was completed. Wide-field fluorescence microscopy and total internal reflection fluorescence microscopy revealed subapical clouds of particles, suggestive of chitosomes moving continuously toward the Spk. Benomyl had no effect on CHS-1–GFP localization, indicating that microtubules are not strictly required for CHS trafficking to the hyphal apex. Conversely, actin inhibitors caused severe mislocalization of CHS-1–GFP, indicating that actin plays a major role in the orderly traffic and localization of CHS-1 at the apex.
Immunolocalization of an Alternative Respiratory Chain in Antonospora (Paranosema) locustae Spores: Mitosomes Retain Their Role in Microsporidial Energy Metabolism
Authors: Dolgikh Viacheslav V. , Senderskiy Igor V. , Pavlova Olga A. , Naumov Anton M. , Beznoussenko Galina V.
Published: February 2011

Microsporidia are a group of fungus-related intracellular parasites with severely reduced metabolic machinery. They lack canonical mitochondria, a Krebs cycle, and a respiratory chain but possess genes encoding glycolysis enzymes, a glycerol phosphate shuttle, and ATP/ADP carriers to import host ATP. The recent finding of alternative oxidase genes in two clades suggests that microsporidial mitosomes may retain an alternative respiratory pathway. We expressed the fragments of mitochondrial chaperone Hsp70 (mitHsp70), mitochondrial glycerol-3-phosphate dehydrogenase (mitG3PDH), and alternative oxidase (AOX) from the microsporidium
Antonospora (Paranosema) locustae
in
Escherichia coli.
Immunoblotting with antibodies against recombinant polypeptides demonstrated specific accumulation of both metabolic enzymes in
A. locustae
spores. At the same time comparable amounts of mitochondrial Hsp70 were found in spores and in stages of intracellular development as well. Immunoelectron microscopy of ultrathin cryosections of spores confirmed mitosomal localization of the studied proteins. Small amounts of enzymes of an alternative respiratory chain in merogonial and early sporogonial stages, alongside their accumulation in mature spores, suggest conspicuous changes in components and functions of mitosomes during the life cycle of microsporidia and the important role of these organelles in parasite energy metabolism, at least at the final stages of sporogenesis.
Lactate Dehydrogenase A Promotes Communication between Carbohydrate Catabolism and Virulence inBacillus cereus
Authors: Laouami Sabrina , Messaoudi Kahina , Alberto François , Clavel Thierry , Duport Catherine
Published: February 2011

The diarrheal potential of aBacillus cereusstrain is essentially dictated by the amount of secreted nonhemolytic enterotoxin (Nhe). Expression of genes encoding Nhe is regulated by several factors, including the metabolic state of the cells. To identify metabolic sensors that could promote communication between central metabolism andnheexpression, we compared four strains of theB. cereusgroup in terms of metabolic andnheexpression capacities. We performed growth performance measurements, metabolite analysis, and mRNA measurements of strains F4430/73, F4810/72, F837/76, and PA cultured under anoxic and fully oxic conditions. The results showed that expression levels ofnheandldhA, which encodes lactate dehydrogenase A (LdhA), were correlated in both aerobically and anaerobically grown cells. We examined the role of LdhA in the F4430/73 strain by constructing anldhAmutant. TheldhAmutation was more deleterious to anaerobically grown cells than to aerobically grown cells, causing growth limitation and strong deregulation of key fermentative genes. More importantly, theldhAmutation downregulated enterotoxin gene expression under both anaerobiosis and aerobiosis, with a more pronounced effect under anaerobiosis. Therefore, LdhA was found to exert a major control on both fermentative growth and enterotoxin expression, and it is concluded that there is a direct link between fermentative metabolism and virulence inB. cereus. The data presented also provide evidence that LdhA-dependent regulation of enterotoxin gene expression is oxygen independent. This study is the first report to describe a role of a fermentative enzyme in virulence inB. cereus.
An Experimentally Validated Genome-Scale Metabolic Reconstruction of
Klebsiella pneumoniae
MGH 78578,
i
YL1228
Authors: Liao Yu-Chieh , Huang Tzu-Wen , Chen Feng-Chi , Charusanti Pep , Hong Jay S. J. , Chang Hwan-You , Tsai Shih-Feng , Palsson Bernhard O. , Hsiung Chao A.
Published: February 2011

Klebsiella pneumoniae
is a Gram-negative bacterium of the family
Enterobacteriaceae
that possesses diverse metabolic capabilities: many strains are leading causes of hospital-acquired infections that are often refractory to multiple antibiotics, yet other strains are metabolically engineered and used for production of commercially valuable chemicals. To study its metabolism, we constructed a genome-scale metabolic model (
i
YL1228) for strain MGH 78578, experimentally determined its biomass composition, experimentally determined its ability to grow on a broad range of carbon, nitrogen, phosphorus and sulfur sources, and assessed the ability of the model to accurately simulate growth versus no growth on these substrates. The model contains 1,228 genes encoding 1,188 enzymes that catalyze 1,970 reactions and accurately simulates growth on 84% of the substrates tested. Furthermore, quantitative comparison of growth rates between the model and experimental data for nine of the substrates also showed good agreement. The genome-scale metabolic reconstruction for
K. pneumoniae
presented here thus provides an experimentally validated
in silico
platform for further studies of this important industrial and biomedical organism.
Mycobacterium tuberculosis
Can Utilize Heme as an Iron Source
Authors: Jones Christopher M. , Niederweis Michael
Published: February 2011

Most iron in mammals is found within the heme prosthetic group. Consequently, many bacterial pathogens possess heme acquisition systems to utilize iron from the host. Here, we demonstrate that
Mycobacterium tuberculosis
can utilize heme as an iron source, suggesting that
M. tuberculosis
possesses a yet-unknown heme acquisition system.
Protection ofBacillus subtilisagainst Cold Stress via Compatible-Solute Acquisition
Authors: Hoffmann Tamara , Bremer Erhard
Published: February 2011

Accumulation of compatible solutes is a strategy widely employed by bacteria to achieve cellular protection against high osmolarity. These compounds are also used in some microorganisms as thermostress protectants. We found thatBacillus subtilisuses the compatible solute glycine betaine as an effective cold stress protectant. Glycine betaine strongly stimulated growth at 15°C and permitted cell proliferation at the growth-inhibiting temperature of 13°C. Initial uptake of glycine betaine at 15°C was low but led eventually to the buildup of an intracellular pool whose size was double that found in cells grown at 35°C. Each of the three glycine betaine transporters (OpuA, OpuC, and OpuD) contributed to glycine betaine accumulation in the cold. Protection against cold stress was also accomplished when glycine betaine was synthesized from its precursor choline. Growth of a mutant defective in the osmoadaptive biosynthesis for the compatible solute proline was not impaired at low temperature (15°C). In addition to glycine betaine, the compatible solutes and osmoprotectantsl-carnitine, crotonobetaine, butyrobetaine, homobetaine, dimethylsulfonioactetate, and proline betaine all served as cold stress protectants as well and were accumulated via known Opu transport systems. In contrast, the compatible solutes and osmoprotectants choline-O-sulfate, ectoine, proline, and glutamate were not cold protective. Our data highlight an underappreciated facet of the acclimatization ofB. subtilisto cold environments and allow a comparison of the characteristics of compatible solutes with respect to their osmotic, heat, and cold stress-protective properties forB. subtiliscells.
Effects of Modified Phycobilin Biosynthesis in the CyanobacteriumSynechococcussp. Strain PCC 7002
Authors: Alvey Richard M. , Biswas Avijit , Schluchter Wendy M. , Bryant Donald A.
Published: February 2011

The pathway for phycocyanobilin biosynthesis inSynechococcussp. strain PCC 7002 comprises two enzymes: heme oxygenase and phycocyanobilin synthase (PcyA). The phycobilin content of cells can be modified by overexpressing genes encoding alternative enzymes for biliverdin reduction. Overexpression of thepebABand HY2 genes, encoding alternative ferredoxin-dependent biliverdin reductases, caused unique effects due to the overproduction of phycoerythrobilin and phytochromobilin, respectively. Colonies overexpressingpebABbecame reddish brown and visually resembled strains that naturally produce phycoerythrin. This was almost exclusively due to the replacement of phycocyanobilin by phycoerythrobilin on the phycocyanin α-subunit. This phenotype was unstable, and such strains rapidly reverted to the wild-type appearance, presumably due to strong selective pressure to inactivatepebABexpression. Overproduction of phytochromobilin, synthesized by theArabidopsis thalianaHY2 product, was tolerated much better. Cells overexpressing HY2 were only slightly less pigmented and blue-green than the wild type. Although thepcyAgene could not be inactivated in the wild type,pcyAwas easily inactivated when cells expressed HY2. These results indicate that phytochromobilin can functionally substitute for phycocyanobilin inSynechococcussp. strain PCC 7002. Although functional phycobilisomes were assembled in this strain, the overall phycobiliprotein content of cells was lower, the efficiency of energy transfer by these phycobilisomes was lower than for wild-type phycobilisomes, and the absorption cross-section of the cells was reduced relative to that of the wild type because of an increased spectral overlap of the modified phycobiliproteins with chlorophylla. As a result, the strain producing phycobiliproteins carrying phytochromobilin grew much more slowly at low light intensity.
Meniscal tears, repairs and replacement: their relevance to osteoarthritis of the knee
Authors: McDermott Ian
Published: February 2011

The menisci of the knee are important load sharers and shock absorbers in the joint. Meniscal tears are common, and whenever possible meniscal tears should be surgically repaired. Meniscectomy leads to a significant increased risk of osteoarthritis, and various options now exist for replacing missing menisci, including the use of meniscal scaffolds or the replacement of the entire meniscus by meniscal allograft transplantation. The field of meniscal surgery continues to develop apace, and the future may lie in growing new menisci by tissue engineering techniques.
Poisoning hospitalisations among reproductive-aged women in the USA, 1998–2006
Authors: Cox Shanna , Kuo Cassie , Jamieson Denise J , Kourtis Athena P , McPheeters Melissa L , Meikle Susan F , Posner Samuel F
Published: February 2011

Objective

To describe poisoning hospitalisations among reproductive-aged women from 1998 to 2006.

Methods

1998–2006 data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilisation Project were used to identify hospitalisations for poisonings among US women aged 15–44 years. Differences in hospitalisation characteristics were compared by intent using χ2statistics. Trends in poisoning hospitalisation rates were calculated overall and by subgroup.

Results

There were approximately 636 000 poisoning hospitalisations in women aged 15–44 years during 1998–2006. Hospitalisations for intentionally self-inflicted poisonings had a higher proportion of women aged 15–24 years and privately insured women than did unintentional poisonings (p<0.001). Poisoning hospitalisations in rural areas and those that resulted in death were more likely to be of undetermined intent than those for which intent was specified (p<0.001). Co-diagnoses of substance abuse (34.5%) or mental disorders (66.5%) were high. The rate of poisoning hospitalisations overall and unintentional poisoning hospitalisations increased 6% and 22%, respectively, during this period (p<0.001). The most frequently diagnosed poisoning agent was acetaminophen. Poisonings attributable to acetaminophen, opioids, central nervous system stimulants and benzodiazepines increased, while poisonings attributable to antidepressants decreased (p<0.05).

Conclusions

The increase in unintentional poisoning hospitalisations among women aged 15–44 years and the changing profile of poisoning agents should inform the healthcare community's poisoning prevention strategies. Poisoning prevention strategies should include a component to address substance abuse and mental health disorders among reproductive-age women.
Injuries and deaths due to victim-activated improvised explosive devices, landmines and other explosive remnants of war in Nepal
Authors: Bilukha Oleg O , Laurenge Hugues , Danee Luhar , Subedi Krishna P , Becknell Kristin
Published: February 2011

Background

Following more than a decade of civil conflict, Nepal is among the countries affected by landmines, victim-activated improvised explosive devices (IED) and other explosive remnants of war (ERW).

Objectives

To assess the magnitude of injuries due to landmines, victim-activated IED and other ERW in Nepal and to describe epidemiological patterns and risk factors for these events.

Methods

Analysis of surveillance data on civilian injuries due to landmines, victim-activated IED and other ERW between July 2006 and June 2010. Data were collected through active community-based prospective surveillance.

Results

Of 307 total casualties, 94 (31%) were female and 169 (55%) were children under 18 years of age. The case–fatality ratio was 14%. The highest number of casualties was in the age group 10–14 years. 233 (76%) injuries were caused by victim-activated IED, 13 (4%) by landmines and 44 (14%) by other ERW. Two types of IED, sutali and socket bombs, caused the majority of injuries (28% and 31%, respectively). 117 (38%) of all injuries occurred in victims' homes and 152 (50%) occurred while victims were tampering with explosive devices.

Conclusions

Substantial numbers of civilians, including women and children, were injured and killed following implementation of the Comprehensive Peace Agreement in 2006. The government of Nepal and humanitarian organisations should continue their efforts to reach communities at highest risk through targeted interventions and nationwide media campaigns to convey the risks of tampering with explosive devices or suspicious objects.
Hypoglycaemia: current management and controversies
Authors: Choudhary Pratik , Amiel Stephanie A
Published: February 2011

Hypoglycaemia is a major burden on patients and society and is often a barrier to the achievement of tight glycaemic control. Intact awareness of hypoglycaemia is crucial to recognising and treating hypoglycaemia before it becomes severe enough to impair consciousness. Repeated hypoglycaemia can lead to impaired awareness increasing the risk of severe hypoglycaemia up to sixfold. Hypoglycaemia is much less common in those with type 2 diabetes, the incidence increasing with longer duration of treatment with insulin, associated comorbidities, and in the elderly. Alcohol, advancing age and exercise may predispose to hypoglycaemia. Newer agents acting via the incretin axis are associated with low rates of hypoglycaemia. Intensification of therapy to achieve tight glucose control can increase the risk of hypoglycaemia in the outpatient as well as critical care setting. In some studies this has also been associated with increased mortality, although causality has not been proven. Insulin treated patients are currently restricted from driving heavy goods vehicles or public service vehicles, although it is unclear if those with diabetes have any higher rates of accidents than those without diabetes. Surveys show that professionals are poor at emphasising the Driver and Vehicle Licensing Agency recommendations for drivers with diabetes in the UK. At every visit, patients with diabetes on hypoglycaemic agents should be assessed for frequency, severity, and awareness of hypoglycaemia. The main therapeutic strategies for reducing hypoglycaemia are structured patient education, use of modern insulin analogues, insulin pumps, and continuous glucose monitoring. Transplantation of islets or whole pancreas is indicated in those with recurrent disabling hypoglycaemia.
Determinants of tetanus and sepsis among the last neonatal deaths at household level in a peri-urban area of India
Authors: Ghosh Rohini , Sharma Arun Kumar
Published: February 2011

Background

India contributes to one quarter of the total number of newborn deaths in the world. Less explored are the causes of these deaths, and household factors and decision makers for antenatal and postnatal care and their association with neonatal mortality.

Objective

This study estimated neonatal mortality rate due to tetanus and sepsis (TS) and tried to identify the risk factors for TS in a peri-urban area of India characterised by a high level of infant and neonatal mortality rate.

Methods

An intensive cross-sectional study was conducted during January to March 2008. A structured interview schedule was developed, after reviewing major demographic and health studies done in India, to collect data from all women selected in the sample villages, situated at a distance of 3–5 km from a primary health centre.

Results

Of the 894 married women (<50 years of age), 109 reported their last pregnancy outcome as neonatal death, and 84 cases of TS were noted. Using forward conditional stepwise logistic regression the risk factors of TS identified were women's age, socioeconomic score, antenatal care, pregnancy complications, and treatment after delivery during the neonatal period.

Conclusions

Independent of social class there is high prevalence of neonatal mortality. There is a close association between utilisation of health care services during pregnancy, postnatal period and neonatal deaths due to TS. It is argued that there is a need for a two pronged approach to reduce neonatal mortality due to TS: (1) to train traditional birth attendants, and expand the reach of existing antenatal care and childbirth facilities; and (2) to empower women to increase their awareness to take decisions about seeking proper medical assistance during pregnancy and childbirth.
Political and practical problems with dangerous dogs
Authors: Grant David
Published: February 2011

The problem of dangerous dogs – particularly ‘status’ or ‘intimidation’ dogs – reflects a wider problem in society, says David Grant : tackling it will require a unified approach
Beta decay of 187W
Authors: Herman A. W. , Heighway E. A. , MacArthur J. D.
Published: February 2011

Coincidence studies have established in the decay scheme of,187W the existence of transitions of energy 7, 36, 77, 455, 589, and 639 keV with intensities of 3.0 ± 0.5%, 0.50 ± 0.06%, 0.31 ± 0.07%, 0.05 ± 0.02%, 0.14 ± 0.04%, and 0.05 ± 0.02% respectively as well as yielding the absolute intensities of the well-known transitions in 187Re. In addition the beta–gamma coincidence measurements have shown that (1) a first-forbidden unique transition feeds the first-excited state of 187Re, (2) there is at most a very weak beta transition to the level at 512 keV, (3) there is no inner beta group of about 300 keV end-point energy and intensity 8% as indicated by several earlier investigations, and (4) the decay energy of 187W to 187Re is 1311 ± 2 keV. The relevance of these observations to the structure of 187Re is discussed.
CRACKING BEHAVIOR OF CARBON BLACK FILLED ELASTOMERS
Authors: GHERIB SAMIA , SATHA HAMID , PELLETIER JEAN MARC , CHAZEAU LAURENT , FRIHI DJAMEL
Published: February 2011

The study of crack propagation in rubber has a very high economic significance but is still not well understood. For this purpose the main objective of this work is to study the fracture behavior of two types of rubber: the NR, which crystallizes under stress and the noncrystallizing SBR. To study the cracking behavior of materials we have made tests of cracking follow-up. The mode of crack propagation has been studied in terms of fillers ratio and traction speed. The unfilled SBR and NR showed simple lateral propagation independently of the test speed, whereas the mode of cracking of filled materials was very influenced by the parameters mentioned previously. The filled SBR can present important deviations of the crack when the fillers ratio is sufficiently high; this deviation is even more pronounced when the speed increases. On the other hand, the natural rubber which crystallizes under stress showed particular mode of propagation characterized by the appearance of longitudinal cracks. This mode of cracking is much more important at low speeds than at the high speeds. It is proposed that the fillers increase the breaking strength of a noncrystallizing material and allows that the crack takes a deviated way if the fillers ratio is sufficiently high. But if it is a material which crystallize like the NR, crystallization and fillers will act simultaneously and the material will be much more resistant which gives rise to a particular mechanism which is the appearance of the longitudinal cracks before the catastrophic rupture.
STRUCTURE AND MAGNETIC PROPERTIES OF NANOSIZED BaFe2O4 MATERIAL
Authors: JAAFAR ADNAN , AREKAT SAFWAN , AL-SAIE AHMED , BOUOUDINA MOHAMED
Published: February 2011

A mixture of BaO and Fe 2 O 3 was mechanically alloyed followed by subsequent annealing. XRD spectra and magnetization hysteresis curves were obtained for both as-milled and annealed samples. XRD pattern of the as-milled powder indicates the formation of an initial amorphous phase. Upon annealing up to 900°C, the material crystallizes into monoferrite BaFe 2 O 4 phase, accompanied by a dramatic change of the magnetic properties. Moreover, the Ms ≈ 5.8 emu/g , Hc ≈ 1.2 kOe , Mr ≈ 2.4 emu/g and an average crystallites size around 23 nm.
MICROWAVE HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF ZnO NANOSHEETS
Authors: BOUDJADAR S. , ACHOUR S. , BOUKHENOUFA N. , GUERBOUS L.
Published: February 2011

ZnO nanosheets with hexagonal wurtzite structure were successfully synthesized by a microwave assisted hydrothermal process using mild conditions and zinc acetate as a precursor. The obtained powder was characterized by X-ray diffraction, environmental scanning electron microscopy, Fourier transmission infrared and room temperature photoluminescence. The size of as-synthesized ZnO nanosheets depends on the precursor concentration and the average diameter ranged between 50 and 600 nm with a thickness in the range of 8–38 nm. The product shows a strong UV emission at 397 nm and a visible blue emission centered at 466 nm.
MAGNETIC PROPERTIES Cu DOPED ZnO:Fe SEMICONDUCTORS
Authors: ZIQ KH. A. , ISMAIL A.
Published: February 2011

Magnetization measurements were performed on a series of Zn 0.9-x Fe 0.1 Cu x O samples (0 ≤ x ≤ 0.10). Small hysteresis losses are seen at low temperatures. The ferromagnetic exchange interaction has been evaluated from the inverse DC magnetic susceptibility versus T and the molecular field theory. We found that Cu -doping greatly enhances the FM exchange interaction, increases the saturation magnetization, hysteresis losses and the magnetic susceptibility. Arrott-Kouvel plot has been used to study the spontaneous magnetic moment at low temperatures. We show that hysteresis losses cannot be taken as the only evidence for the appearance of the ferromagnetic order in these semiconducting semi-magnetic materials.
UV–VISIBLE, FTIR AND RAMAN SPECTRA FROM LARGE BAND-GAP HYDROFLUORINATED AMORPHOUS SILICON–CARBON THIN FILMS
Authors: AREKAT SAFWAN R.
Published: February 2011

Hydrofluorinated amorphous silicon–carbon alloy films (a-Si,C:H,F) were grown by a CVD glow-discharge method. The samples were prepared from SiH4 , H2 and CF4 source gas mixtures. The structural and bonding characterstics of the materials were studied using FTIR and Raman spectroscopy. In addition to hydrogen passivation, the inclusion of fluorine in the films is found to further suppress undesirable disorder states. The optical band gap E opt of the materials was determined from the Tauc relation for the optical absorption spectra. They were found to increase from about 2 eV to 3.5 eV with increasing carbon content in the samples.
CONTINGENT VALUATION STUDY ON WILLINGNESS-TO-PAY FOR SUSTAINABLE FOREST PRODUCTS
Authors: HARRISON JANE LINDSAY , HITZHUSEN FRED
Published: February 2011

This research study investigates the market and non-market benefits and costs of adopting a forest resources policy aimed at environmentally responsible purchasing at a large university. I use benefit-cost analysis and contingent valuation methods to determine the population's willingness-to-pay (WTP) for environmentally responsible forest products. Econometric analysis reveals that past WTP and belief that the forest resources policy will improve the environment positively affect WTP, while position as a staff member decreases WTP. This methodology can be used for other products that have non-market values like cafeteria compost and by other large purchasing entities such as corporations and government agencies.
Absorption Change Induced by Electric Field of an InGaAsP/InAlAs/InP Asymmetric Quantum Well Structure Gown on InP Substrates
Authors: Kawamura Yuichi , Shono Takuya
Published: February 2011

An InGaAsP/InAlAs/InP asymmetric quantum well structure was proposed and fabricated, where a large change in the wave function overlap of electrons and holes can be expected with the application of a low voltage. It was demonstrated by using photocurrent measurements that a large absorption change can be realized by applying a bias within ±1 V. The observed absorption change was caused by a large change in the wave function overlap of electrons and holes with the application of an opposite electric field.
Endotoxemia decreases matching of regional blood flow and O2 delivery to O2 uptake in the porcine left ventricle
Authors: Alders David J. C. , Groeneveld A. B. Johan , Binsl Thomas W. , de Kanter Frans J. , van Beek Johannes H. G. M.
Published: February 2011

Heterogeneity of regional coronary blood flow is caused in part by heterogeneity in O2 demand in the normal heart. We investigated whether myocardial O2 supply/demand mismatching is associated with the myocardial depression of sepsis. Regional blood flow (microspheres) and O2 uptake ([13C]acetate infusion and analysis of resultant NMR spectra) were measured in about nine contiguous tissue samples from the left ventricle (LV) in each heart. Endotoxemic pigs ( n = 9) showed hypotension at unchanged cardiac output with a fall in LV stroke work and first derivative of LV pressure relative to controls ( n = 4). Global coronary blood flow and O2 delivery were maintained. Lactate accumulated in arterial blood, but net lactate extraction across the coronary bed was unchanged during endotoxemia. When LV O2 uptake based on blood gas versus NMR data were compared, the correlation was 0.73 ( P = 0.007). While stable over time in controls, regional blood flows were strongly redistributed during endotoxin shock, with overall flow heterogeneity unchanged. A stronger redistribution of blood flow with endotoxin was associated with a larger fall in LV function parameters. Moreover, the correlation of regional O2 delivery to uptake fell from r = 0.73 ( P < 0.001) in control to r = 0.18 ( P = 0.25, P = 0.009 vs. control) in endotoxemic hearts. The results suggest a redistribution of LV regional coronary blood flow during endotoxin shock in pigs, with regional O2 delivery mismatched to O2 demand. Mismatching may underlie, at least in part, the myocardial depression of sepsis.
Secretoneurin facilitates endothelium-dependent relaxations in porcine coronary arteries
Authors: Chan Calvin KY , Vanhoutte Paul M.
Published: February 2011

Secretoneurin enhances the adhesion and transendothelial migration properties of monocytes and is a part of the peptide family encoded by the secretogranin II gene. The expression of the secretogranin II gene is upregulated in senescent endothelium. The present study was designed to examine the effects of secretoneurin on endothelium-dependent responsiveness. Isometric tension was measured in rings (with or without endothelium) of porcine coronary arteries. Secretoneurin did not induce contraction of quiescent or contracted rings. In preparations contracted by U-46619, relaxation was observed with high concentrations of the peptide. This relaxation was endothelium dependent and reduced by the nitric oxide synthase inhibitor Nω-nitro-l-arginine methyl ester (l-NAME). It was abolished when the preparations were incubated with l-NAME in combination with the cyclooxygenase inhibitor indomethacin. The relaxation was not affected by the combination of 1-[(2-chlorophenyl)diphenylmethyl]-1H-pyrazole (TRAM-34) and 6,12,19,20,25,26-hexahydro-5,27:13,18:21,24-trietheno-11,7-etheno-7H-dibenzo[b,m][1,5,12,16]tetraazacyclotricosine-5,13-diiumditrifluoroacetate hydrate (UCL 1684), which abrogates endothelium-dependent hyperpolarizations. These results indicate that secretoneurin acutely induces relaxation through the activation of endothelial nitric oxide synthase (eNOS) and cyclooxygenase, with nitric oxide playing the dominant role. Prolonged (24 h) incubation with physiological concentrations of secretoneurin enhanced the relaxations to bradykinin and to the calcium ionophore A-23187, but this difference was not observed in preparations incubated with l-NAME or the calmodulin antagonist calmidazolium. Under these conditions, the relaxation to sodium nitroprusside remained unchanged. Incubation with secretoneurin significantly augmented the expression of eNOS and calmodulin as well as the dimerization of eNOS in cultures of porcine coronary arterial endothelial cells. These observations suggest that secretoneurin not only acutely causes but also, upon prolonged exposure, enhances endothelium-dependent relaxations.
Silencing of cardiac mitochondrial NHE1 prevents mitochondrial permeability transition pore opening
Authors: Villa-Abrille María C. , Cingolani Eugenio , Cingolani Horacio E. , Alvarez Bernardo V.
Published: February 2011

Inhibition of Na+/H+exchanger 1 (NHE1) reduces cardiac ischemia-reperfusion (I/R) injury and also cardiac hypertrophy and failure. Although the mechanisms underlying these NHE1-mediated effects suggest delay of mitochondrial permeability transition pore (MPTP) opening, and reduction of mitochondrial-derived superoxide production, the possibility of NHE1 blockade targeting mitochondria has been incompletely explored. A short-hairpin RNA sequence mediating specific knock down of NHE1 expression was incorporated into a lentiviral vector (shRNA-NHE1) and transduced in the rat myocardium. NHE1 expression of mitochondrial lysates revealed that shRNA-NHE1 transductions reduced mitochondrial NHE1 (mNHE1) by ∼60%, supporting the expression of NHE1 in mitochondria membranes. Electron microscopy studies corroborate the presence of NHE1 in heart mitochondria. Immunostaining of rat cardiomyocytes also suggests colocalization of NHE1 with the mitochondrial marker cytochrome c oxidase. To examine the functional role of mNHE1, mitochondrial suspensions were exposed to increasing concentrations of CaCl2to induce MPTP opening and consequently mitochondrial swelling. shRNA-NHE1 transduction reduced CaCl2-induced mitochondrial swelling by 64 ± 4%. Whereas the NHE1 inhibitor HOE-642 (10 μM) decreased mitochondrial Ca2+-induced swelling in rats transduced with nonsilencing RNAi (37 ± 6%), no additional HOE-642 effects were detected in mitochondria from rats transduced with shRNA-NHE1. We have characterized the expression and function of NHE1 in rat heart mitochondria. Because mitochondria from rats injected with shRNA-NHE1 present a high threshold for MPTP formation, the beneficial effects of NHE1 inhibition in I/R resulting from mitochondrial targeting should be considered.
TGF-β2 treatment enhances cytoprotective factors released from embryonic stem cells and inhibits apoptosis in infarcted myocardium
Authors: Singla Dinender K. , Singla Reetu D. , Lamm Stephanie , Glass Carley
Published: February 2011

We investigated whether factors released from mouse embryonic stem (ES) cells primed with and without transforming growth factor (TGF)-β2 inhibit iodoacetic acid (IAA)- and H2O2-induced apoptosis in the cell culture system as well as after transplantation in the infarcted heart. We generated conditioned media (CMs) from ES cells primed with and without TGF-β2 and determined their effects on IAA- and H2O2-induced apoptosis in H9c2 cells. We also transplanted both ES-CMs in the infarcted heart to determine the effects on apoptosis and cardiac function after myocardial infarction (MI) at day (D)1 and D14. Terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling (TUNEL) staining, apoptotic ELISA, and cell viability data demonstrated significantly ( P < 0.05) reduced apoptosis with ES-CM compared with controls in both cell culture models. Moreover, TGF-β2-primed ES-CM (T-ES-CM) demonstrated enhanced beneficial effects, with further reduced ( P < 0.05) apoptosis compared with ES-CM, suggesting the a presence of additional cytoprotective released factors after TGF-β2 treatment. Next, our in vivo apoptosis data suggested significant decrease in apoptosis with both ES-CMs compared with MI alone at D1 and D14. Notably, T-ES-CM demonstrated significant ( P < 0.05) inhibition of apoptosis and fibrosis with improved cardiac function compared with ES-CM at D14, whereas no such effects were observed at D1. Next, we confirmed that apoptosis is mediated through a prosurvival Akt pathway. Moreover, we determined that after TGF-β2 treatment there was a two- to fivefold increase in cytoprotective released factors (interleukin-10, stem cell factor, tissue inhibitor of matrix metalloproteinase-1, and VEGF) with T-ES-CM compared with ES-CM. In conclusion, we suggest that factors released from ES cells with and without TGF-β2 treatment contain antiapoptotic factors that inhibit apoptosis in vitro and in vivo. We also suggest that T-ES-CM demonstrates additional beneficial effects that provide useful information for future therapeutic applications in regenerative medicine.
Ca2+sensitization and PKC contribute to exercise training-enhanced contractility in porcine collateral-dependent coronary arteries
Authors: Robles Juan Carlos , Sturek Michael , Parker Janet L. , Heaps Cristine L.
Published: February 2011

Exercise training enhances endothelium-dependent coronary vasodilatation, improving perfusion and contractile function of collateral-dependent myocardium. Paradoxically, studies from our laboratory have revealed increased Ca2+-dependent basal active tone in collateral-dependent arteries of exercise-trained pigs. In this study, we tested the hypothesis that exercise training enhances agonist-mediated contractile responses of collateral-dependent arteries by promoting Ca2+sensitization. Ameroid constrictors were surgically placed around the proximal left circumflex coronary (LCX) artery of female Yucatan miniature pigs. Eight weeks postoperatively, pigs were randomized into sedentary (pen confined) or exercise-training (treadmill run; 5 days/wk; 14 wk) groups. Arteries (∼150 μm luminal diameter) were isolated from the collateral-dependent and nonoccluded (left anterior descending artery supplied) myocardial regions, and measures of contractile tension or simultaneous tension and intracellular free Ca2+concentration levels (fura-2) were completed. Exercise training enhanced contractile responses to endothelin-1 in collateral-dependent compared with nonoccluded arteries, an effect that was more pronounced in the presence of nitric oxide synthase inhibition ( Nω-nitro-l-arginine methyl ester; 100 μM). Contractile responses to endothelin-1 were not altered by coronary occlusion alone. Exercise training produced increased tension at comparable levels of intracellular free Ca2+concentration in collateral-dependent compared with nonoccluded arteries, indicative of exercise training-enhanced Ca2+sensitization. Inhibition of PKC (calphostin C; 1 μM), but not Rho-kinase (Y-27632, 10 μM; or hydroxyfasudil, 30 μM), abolished the training-enhanced endothelin-1-mediated contractile response. Exercise training also increased sensitivity to the PKC activator phorbol 12,13-dibutyrate in collateral-dependent compared with nonoccluded arteries. Taken together, these data reveal that exercise training enhances endothelin-1-mediated contractile responses in collateral-dependent coronary arteries likely via increased PKC-mediated Ca2+sensitization.
CC chemokine receptor 5 deletion impairs macrophage activation and induces adverse remodeling following myocardial infarction
Authors: Zamilpa Rogelio , Kanakia Rushit , Cigarroa Joaquin , Dai Qiuxia , Escobar G. Patricia , Martinez Hernan , Jimenez Fabio , Ahuja Seema S. , Lindsey Merry L.
Published: February 2011

Post-myocardial infarction (MI), chemokine homing of inflammatory cells into the injured left ventricle (LV) regulates ventricular remodeling, in part by stimulating the extracellular matrix response. The CC chemokine receptor 5 (CCR5) is a key chemokine receptor expressed on macrophages, and CCR5 ligands are highly upregulated post-MI. We hypothesized that deletion of CCR5 would attenuate adverse remodeling by decreasing inflammatory cell recruitment. Accordingly, we examined LV function, macrophage recruitment and activation, and collagen content in wild-type (WT, n = 25) and CCR5 null ( n = 33) mice at 7 days post-MI. Both groups had similar infarct sizes (44 ± 2% in WT and 42 ± 2% in CCR5 null; P = 0.37). However, the LV remodeling index (end diastolic volume/LV mass) increased to a larger extent in CCR5 null (1.28 ± 0.08 μl/mg for CCR5 null and 1.02 ± 0.06 μl/mg for WT; P < 0.05). Although numbers of infiltrated macrophages were similar in WT and CCR5 null mice, CCR5-deficient macrophages isolated from the infarct zone displayed >50% decrease in gene expression levels of proinflammatory activation markers (interleukin-1β, interleukin-6, and tumor necrosis factor-α), as well as anti-inflammatory activation markers (arginase 1, CD163, mannose receptor, and transforming growth factor-β1) compared with WT (all P < 0.05). Concomitant with the reduced macrophage activation, heat shock protein-47 and collagen type I precursor levels in the infarct region decreased in the CCR5 null (1.2 ± 0.3 units in the CCR5 null and 2.3 ± 0.4 units in the WT; P < 0.05), while collagen fragments increased (88.3 ± 5.9 units in the CCR5 null and 32.7 ± 8.5 units in the WT; P < 0.05). We conclude that CCR5 deletion impairs LV remodeling by hindering macrophage activation, which stimulates an imbalance in collagen metabolism and increases the remodeling index.
Ventricular pacing-induced loss of contractile function and development of epicardial inflammation
Authors: Yamazaki Katrina Go , Villarreal Francisco J.
Published: February 2011

Perturbations in the normal sequence of ventricular activation can create regions of early and late activation, leading to dysynchronous contraction and areas of dyskinesis. Dyskinesis occurs across the left ventricular (LV) wall, and its presence may have important consequences on cardiac structure and function in normal and failing hearts. Acutely, dyskinesis can trigger inflammation and, in the long term (6 wk and above), leads to LV remodeling. The mechanisms that trigger these changes are unknown. To gain further insight, we used a canine model to evaluate transumural changes in myocardial function and inflammation induced by epicardial LV pacing. The results indicate that 4 h of LV suprathreshold pacing resulted in a 30% local loss of endocardial thickening. Assessment of neutrophil infiltration showed a significant approximately fivefold increase in myeloperoxidase activity in the epicardium versus the midwall/endocardium. Matrix metalloproteinase-9 activity increased ∼2 fold in the epicardium and ROS generation increased ∼2.5-fold compared with the midwall/endocardium. To determine the effects that electrical current alone has on these end points, a group of animals was subjected to subthreshold pacing. Significant increases were observed only in epicardial myeloperoxidase levels. Thus, the results indicate that transmural dyskinesis induced by suprathreshold epicardial LV activation triggers a localized epicardial inflammatory response, whereas subthreshold stimulation appears to solely induce the trapping of leucocytes. Suprathreshold pacing also induces a loss of endocardial function. These results may have important implications as to the nature of the mechanisms that trigger the inflammatory response and possibly long-term remodeling in the setting of dysynchrony.
Caveolin-1 deficiency exacerbates cardiac dysfunction and reduces survival in mice with myocardial infarction
Authors: Jasmin Jean-François , Rengo Giuseppe , Lymperopoulos Anastasios , Gupta Ratika , Eaton Gregory J. , Quann Kevin , Gonzales Donna M. , Mercier Isabelle , Koch Walter J. , Lisanti Michael P.
Published: February 2011

Caveolin (Cav)-1 has been involved in the pathogenesis of ischemic injuries. For instance, modulations of Cav-1 expression have been reported in animal models of myocardial infarction and cerebral ischemia-reperfusion. Furthermore, ablation of the Cav-1 gene in mice has been shown to increase the extent of ischemic injury in models of cerebral and hindlimb ischemia. Cav-1 has also been suggested to play a role in myocardial ischemic preconditioning. However, the role of Cav-1 in myocardial ischemia (MI)-induced cardiac dysfunction still remains to be determined. We determined the outcome of a permanent left anterior descending coronary artery (LAD) ligation in Cav-1 knockout (KO) mice. Wild-type (WT) and Cav-1 KO mice were subjected to permanent LAD ligation for 24 h. The progression of ischemic injury was monitored by echocardiography, hemodynamic measurements, 2,3,5-triphenyltetrazolium chloride staining, β-binding analysis, cAMP level measurements, and Western blot analyses. Cav-1 KO mice subjected to LAD ligation display reduced survival compared with WT mice. Despite similar infarct sizes, Cav-1 KO mice subjected to MI showed reduced left ventricular (LV) ejection fraction and fractional shortening as well as increased LV end-diastolic pressures compared with their WT counterparts. Mechanistically, Cav-1 KO mice subjected to MI exhibit reduced β-adrenergic receptor density at the plasma membrane as well as decreased cAMP levels and PKA phosphorylation. In conclusion, ablation of the Cav-1 gene exacerbates cardiac dysfunction and reduces survival in mice subjected to MI. Mechanistically, Cav-1 KO mice subjected to LAD ligation display abnormalities in β-adrenergic signaling.
Central command does not decrease cardiac parasympathetic efferent nerve activity during spontaneous fictive motor activity in decerebrate cats
Authors: Kadowaki Akito , Matsukawa Kanji , Wakasugi Rie , Nakamoto Tomoko , Liang Nan
Published: February 2011

To examine whether withdrawal of cardiac vagal efferent nerve activity (CVNA) predominantly controls the tachycardia at the start of exercise, the responses of CVNA and cardiac sympathetic efferent nerve activity (CSNA) were directly assessed during fictive motor activity that occurred spontaneously in unanesthetized, decerebrate cats. CSNA abruptly increased by 71 ± 12% at the onset of the motor activity, preceding the tachycardia response. The increase in CSNA lasted for 4–5 s and returned to the baseline, even though the motor activity was not ended. The increase of 6 ± 1 beats/min in heart rate appeared with the same time course of the increase in CSNA. In contrast, CVNA never decreased but increased throughout the motor activity, in parallel with a rise in mean arterial blood pressure (MAP). The peak increase in CVNA was 37 ± 9% at 5 s after the motor onset. The rise in MAP gradually developed to 21 ± 2 mmHg and was sustained throughout the spontaneous motor activity. Partial sinoaortic denervation (SAD) blunted the baroreflex sensitivity of the MAP-CSNA and MAP-CVNA relationship to 22–33% of the control. Although partial SAD blunted the initial increase in CSNA to 53% of the control, the increase in CSNA was sustained throughout the motor activity. In contrast, partial SAD almost abolished the increase in CVNA during the motor activity, despite the augmented elevation of 31 ± 1 mmHg in MAP. Because afferent inputs from both muscle receptors and arterial baroreceptors were absent or greatly attenuated in the partial SAD condition, only central command was operating during spontaneous fictive motor activity in decerebrate cats. Therefore, it is likely that central command causes activation of cardiac sympathetic outflow but does not produce withdrawal of cardiac parasympathetic outflow during spontaneous motor activity.