bluuebunny/crossref_metadata_2025 huggingface dataset:
Muscarinic ACh Receptor Activation Causes Transmitter Release From Isolated Frog Vestibular Hair Cells
Authors: Derbenev Andrei V. , Linn Cindy L. , Guth Paul S.
Published: October 2005

In the frog, vestibular efferent fibers innervate only type-II vestibular hair cells. Through this direct contact with hair cells, efferent neurons are capable of modifying transmitter release from hair cells onto primary vestibular afferents. The major efferent transmitter, acetylcholine (ACh), is known to produce distinct pharmacological actions involving several ACh receptors. Previous studies have implicated the presence of muscarinic ACh receptors on vestibular hair cells, although, surprisingly, a muscarinic-mediated electrical response has not been demonstrated in solitary vestibular hair cells. This study demonstrates that muscarinic receptors can evoke transmitter release from vestibular hair cells. Detection of this release was obtained through patch-clamp recordings from catfish cone horizontal cells, serving as glutamate detectors after pairing them with isolated frog semicircular canal hair cells in a two-cell preparation. Although horizontal cells alone failed to respond to carbachol, application of 20 μM carbachol to the two-cell preparation resulted in a horizontal cell response that could be mimicked by exogenous application of glutamate. All of the horizontal cells in the two-cell preparation responded to 20 μM CCh. Furthermore, this presumed transmitter release persisted in the presence of d-tubocurarine at concentrations that block all known hair cell nicotinic ACh receptors. The effect on the detector cell, imparted by the carbachol application to the hair cell-horizontal cell preparation, was blocked both by 2-amino-5-phosphonopentanoic acid, a selective N-methyl-d-aspartate antagonist, and the muscarinic antagonist, atropine. Thus vestibular hair cells from the frog semicircular canal can be stimulated to release transmitter by activating their muscarinic receptors.
Attention and Memory-Related Responses of Neurons in the Lateral Intraparietal Area During Spatial and Shape-Delayed Match-to-Sample Tasks
Authors: Sereno Anne B. , Amador Silvia C.
Published: October 2005

When a monkey attends to, remembers, and looks toward targets, the activity of some neurons in the lateral intraparietal area (LIP) changes. We recorded from isolated neurons during both a spatial and a shape match-to-sample task to examine and characterize voluntary active processes in LIP. Many LIP neurons show spatially selective activity during the delay period that depends on the location of the sample, but for most cells, this activity does not differ between the two tasks. Although much past work in posterior parietal cortex has explained responses in this region in terms of active processes such as decision-making and motor planning, our findings suggest that much of that activity represents more passive processing. Nevertheless, we do see a significant minority of units that demonstrate instruction-dependent activity during the delay period, suggesting that these units could represent the neural correlates of voluntary or active processes. Separately, we found that during the presentation of the sample stimulus and test array, some units show stronger responses to the stimulus in the shape-matching task when the animal must attend to the shape of a stimulus. This elevated response to the sample during the shape task provides evidence for feature-based attention in LIP. Attention to shape is a property that has not previously been described in primate cortex.
Cholinergic and Serotonergic Excitation of Ascending Commissural Neurons in the Thoraco-Lumbar Spinal Cord of the Neonatal Mouse
Authors: Carlin K. P. , Dai Y. , Jordan L. M.
Published: October 2005

Locomotion requires the coordination of the two sides of the spinal cord—a function fulfilled by commissural neurons. Ascending commissural neurons (aCNs) are known to be rhythmically active during locomotion, and mice lacking a population of aCNs display uncoupling between the left and right hemicords during locomotion. Acetylcholine (ACh) applied to the isolated spinal cord commonly produces left–right alternation, with co-contraction of ipsilateral flexor and extensor motoneuron groups. In this study, aCNs were examined in the neonatal mouse spinal cord after retrograde labeling with a fluorescent dextran. The axons of these cells crossed in the ventral commissure with many crossing in the same transverse plane as the cell body. For cells located in lamina VII and VIII, ACh (10–50 μM) depolarized 92% (13/14) of the cells tested. ACh depolarized and increased the excitability of aCNs in the presence of a decrease in input resistance. ACh was without significant effect on afterhyperpolarization amplitude or voltage threshold of action potential initiation. In those cells sensitive to application of ACh, 90% (9/10 cells) were also depolarized by 5HT (10–50 μM). Application of 5HT significantly increased the input resistance of these cells, and this effect was likely responsible for the observed increase in excitability, because significant effects on the afterhyperpolarization and voltage threshold were again not detected. The high proportion of aCNs excited by both ACh and 5HT suggests that direct activation of aCNs by these two neurotransmitters contributes to the production of a bilaterally coordinated locomotor-like rhythm in the isolated spinal cord.
Position of a Chest Tube at Video-Assisted Thoracoscopic Surgery for Spontaneous Pneumothorax
Authors: Chen Fengshi , Yamada Tetsu , Aoyama Akihiro , Isowa Noritaka , Chihara Koji
Published: October 2005

Background:Video-assisted thoracoscopic surgery (VATS) is a good therapeutic option for young patients with primary spontaneous pneumothorax (PSP), but there sometimes exists unexpected prolonged hospital stay due to air leak after the operation. Objectives: The goal of this retrospective study was to clarify if the position of the chest tube placed at VATS for PSP affected the periods of postoperative hospital stay. Methods: Seventy-one cases with PSP under age 40 who undertook VATS from January 1994 to February 2001 were examined for several factors. They were classified into two groups by the location of the tip of the chest tube placed at VATS as follows: upper medial pleural space (group I) and outside of there (group II). Results:Fifty-three of the 71 cases (75%) were classified in group I and 18 (25%) were in group II. Between the two groups, there were no differences as to preoperative characteristics of the patients and intraoperative findings of blebs or bullae. On the other hand, postoperative air leak-related complications were more frequent in group II than in group I (p = 0.004). Mean postoperative hospital stay was 5.1 ± 1.9 days in group I and 8.4 ± 4.3 days in group II (p < 0.0001). Conclusions:Patients with the tip of the chest tube in the upper medial pleural space at VATS could be discharged earlier than the other patients. The chest tube placement is one of the important factors for the outcome of VATS for PSP.
Alcohol-Induced Lung Damage and Increased Oxidative Stress
Authors: Aytacoglu B.N. , Calıkoglu M. , Tamer L. , Coskun B. , Sucu N. , Köse N. , Aktas S. , Dikmengil M.
Published: October 2005

Background: Alcohol-induced lung damage may be associated with increased oxidative stress. Objective: Our aim was to investigate alcohol-induced changes in the biochemistry and histopathology of the lung. Methods: Rats were divided into two groups, a control group and an ethanol group. The ethanol group received 2 g/kg ethanol (total: 3 ml) intraperitoneally. The controls were given the same amount of saline via the same route. Three hours later, the rats were sacrificed, and blood and lung tissue samples were obtained. Oxidative stress was assessed by measuring the levels of erythrocyte reduced glutathione (GSH), tissue malondialdehyde (MDA), myeloperoxidase (MPO) and Na+-K+ ATPase. Histopathologic evaluation of the lung tissues was also performed. Results: In the ethanol group, serum and tissue MDA levels and MPO activities were increased (p = 0.007, p = 0.001 and p = 0.000), and lung tissue Na+-K+ ATPase activities and erythrocyte GSH were decreased (p = 0.001 and p = 0.000) compared to the controls. Histopathologic examination demonstrated alveolocapillary thickening, alveolar degeneration, leukocyte infiltration and erythrocyte extravasation in the lungs of the ethanol group (p < 0.05). Conclusion: These results suggest that high-doseacute alcohol administration aggravates systemic and local oxidative stress leading to acute lung injury, ranging from mild pulmonary dysfunction to severe lung injury. It should be borne in mind that rapid onset of the acute respiratory distress syndrome (ARDS) may also be due to increased oxidative stress following alcohol abuse, especially when ischemic disturbances, e.g. coronary heart disease, acute ischemia of the extremities and traumatic accidents, are concomitantly present. Therefore, precautions against ARDS may prevent morbidity and mortality in alcohol-induced lung damage in at-risk patients.
In the Shadow of Race: Immigrant Status and Mental Health
Authors: Kurz Brenda , Malcolm Barris , Cournoyer David
Published: October 2005

This study explored the relative usefulness of measures of race, ethnicity, and acculturation in understanding the mental health of an ethnically diverse group of low-income women. The 194 women who were enrolled in the Women, Infant and Child program showed no racial/ethnic variation in the prevalence of mental health symptoms and a general mental health syndrome, as measured by the PrimeMD-PHQ screening tool. However, immigrants or migrants were less likely than were natives to report symptoms of depression and distress. Speaking primarily a language other than English was associated with symptoms of distress. The findings suggest that for treatment and program planning for low-income women, racial/ethnic designations may be less useful than may the more direct measures of the cultural differences they presume to reflect.
Belief in Personal Control Among Low-Income African American, Puerto Rican, and European American Single Mothers
Authors: Sparks Anne , Peterson N. Andrew , Tangenberg Kathleen
Published: October 2005

This study examined belief in personal control among low-income single mothers (African American, Puerto Rican, and European American) in an economically distressed region in the Northeast, who were recruited from child care centers and community programs. A factor analysis of the Belief in Personal Control Scale supported the three hypothesized subscales of the measure—God-mediated control, external control, and exaggerated personal control. The results indicate that African American women had stronger God-mediated control and weaker external control than did European American women and that Puerto Rican women had greater external control and weaker exaggerated personal control than did European American women. They suggest that an instrument that measures belief in personal control can contribute to efforts to understand low-income single mothers’ perceptions of their situations and that religious faith should be further explored as a key component of belief in personal control.
Better prediction of protein contact number using a support vector regression analysis of amino acid sequence
Authors: Yuan Zheng
Published: October 2005

Background

Protein tertiary structure can be partly characterized via each amino acid's contact number measuring how residues are spatially arranged. The contact number of a residue in a folded protein is a measure of its exposure to the local environment, and is defined as the number of C
β
atoms in other residues within a sphere around the C
β
atom of the residue of interest. Contact number is partly conserved between protein folds and thus is useful for protein fold and structure prediction. In turn, each residue's contact number can be partially predicted from primary amino acid sequence, assisting tertiary fold analysis from sequence data. In this study, we provide a more accurate contact number prediction method from protein primary sequence.

Results

We predict contact number from protein sequence using a novel support vector regression algorithm. Using protein local sequences with multiple sequence alignments (PSI-BLAST profiles), we demonstrate a correlation coefficient between predicted and observed contact numbers of 0.70, which outperforms previously achieved accuracies. Including additional information about sequence weight and amino acid composition further improves prediction accuracies significantly with the correlation coefficient reaching 0.73. If residues are classified as being either "contacted" or "non-contacted", the prediction accuracies are all greater than 77%, regardless of the choice of classification thresholds.

Conclusion

The successful application of support vector regression to the prediction of protein contact number reported here, together with previous applications of this approach to the prediction of protein accessible surface area and B-factor profile, suggests that a support vector regression approach may be very useful for determining the structure-function relation between primary protein sequence and higher order consecutive protein structural and functional properties.
Efficient expression of transgenes in adult zebrafish by electroporation
Authors: Rambabu K Murali , Rao S Hari Narayana , Rao N Madhusudhana
Published: October 2005

Background

Expression of transgenes in muscle by injection of naked DNA is widely practiced. Application of electrical pulses at the site of injection was demonstrated to improve transgene expression in muscle tissue. Zebrafish is a precious model to investigate developmental biology in vertebrates. In this study we investigated the effect of electroporation on expression of transgenes in 3–6 month old adult zebrafish.

Results

Electroporation parameters such as number of pulses, voltage and amount of plasmid DNA were optimized and it was found that 6 pulses of 40 V·cm-1 at 15 μg of plasmid DNA per fish increased the luciferase expression 10-fold compared to controls. Similar enhancement in transgene expression was also observed in Indian carp (Labeo rohita). To establish the utility of adult zebrafish as a system for transient transfections, the strength of the promoters was compared in A2 cells and adult zebrafish after electroporation. The relative strengths of the promoters were found to be similar in cell lines and in adult zebrafish. GFP fluorescence in tissues after electroporation was also studied by fluorescence microscopy.

Conclusion

Electroporation after DNA injection enhances gene expression 10-fold in adult zebrafish. Electroporation parameters for optimum transfection of adult zebrafish with tweezer type electrode were presented. Enhanced reporter gene expression upon electroporation allowed comparison of strengths of the promoters in vivo in zebrafish.
Impulse and Constraint: Perspectives From Personality Psychology, Convergence With Theory in Other Areas, and Potential for Integration
Authors: Carver Charles S.
Published: October 2005

A behavioral dimension of impulse versus constraint has long been observed by personality psychologists. This article begins by reviewing processes underlying this dimension from the perspectives of several personality theories. Some cases of constraint reflect inhibition due to anxiety, but some theories suggest other roots for constraint. Theories from developmental psychology accommodate both possibilities by positing 2 sorts of control over action. These modes of influence strongly resemble those predicated in some personality theories and also 2 modes of function that are asserted by some cognitive and social psychological theories. Several further literatures are considered, to which 2-mode models seem to contribute meaningfully. The article closes by addressing questions raised by these ideas, including whether the issue of impulse versus constraint applies to avoidance as well as to approach.
Combined deficiencies ofMsx1andMsx2cause impaired patterning and survival of the cranial neural crest
Authors: Ishii Mamoru , Han Jun , Yen Hai-Yun , Sucov Henry M. , Chai Yang , Maxson Robert E.
Published: October 2005

The neural crest is a multipotent, migratory cell population that contributes to a variety of tissues and organs during vertebrate embryogenesis. Here, we focus on the function of Msx1 and Msx2, homeobox genes implicated in several disorders affecting craniofacial development in humans. We show that Msx1/2mutants exhibit profound deficiencies in the development of structures derived from the cranial and cardiac neural crest. These include hypoplastic and mispatterned cranial ganglia, dysmorphogenesis of pharyngeal arch derivatives and abnormal organization of conotruncal structures in the developing heart. The expression of the neural crest markers Ap-2α, Sox10 and cadherin 6 (cdh6) in Msx1/2mutants revealed an apparent retardation in the migration of subpopulations of preotic and postotic neural crest cells, and a disorganization of neural crest cells paralleling patterning defects in cranial nerves. In addition, normally distinct subpopulations of migrating crest underwent mixing. The expression of the hindbrain markers Krox20 and Epha4 was altered in Msx1/2 mutants, suggesting that defects in neural crest populations may result, in part, from defects in rhombomere identity. Msx1/2 mutants also exhibited increased Bmp4expression in migratory cranial neural crest and pharyngeal arches. Finally,proliferation of neural crest-derived mesenchyme was unchanged, but the number of apoptotic cells was increased substantially in neural crest-derived cells that contribute to the cranial ganglia and the first pharyngeal arch. This increase in apoptosis may contribute to the mispatterning of the cranial ganglia and the hypoplasia of the first arch.
Safety and Reliability Aspects for Active Magnetic Bearing Applications - A Survey
Authors: Schweitzer G
Published: October 2005

The application of magnetic bearings for rotating machinery has become state of the art and spans from research prototypes to industrial series. Users are aware that beyond functionality the aspects of safety and related areas become increasingly important. This survey addresses the issues of safety and reliability, being a part of dependability. It gives a review on existing approaches, and it shows numerous examples of problems and solutions. Review topics are safety-oriented design methods, software tools, redundancy, robust control, and retainer bearings. Finally, the concept of smart machines is introduced as a way for further improving safety and dependability of machinery with active magnetic bearings.
Recursive Backstepping Stabilization of a Wheeled Mobile Robot
Authors: Mnif F , Yahmadi A S
Published: October 2005

This research is aimed at the development of a dynamic control to enhance the performance of the existing dynamic controllers for mobile robots. System dynamics of the car-like robot with non-holonomic constraints were employed. A backstepping approach for the design of a discontinuous state feedback controller is used for the design of the controller. It is shown that the origin of the closed-loop system can be made stable in the sense of Lyapunov. The control design is made on the basis of a suitable Lyapunov function candidate. The effectiveness of the proposed approach is tested through simulation on a car-like vehicle mobile robot.
U-Model-Based Internal Model Control for Non-Linear Dynamic Plants
Authors: Shafiq M , Haseebuddin M
Published: October 2005

In this paper, a U-model in the internal model control (IMC) structure is used. The U-model is a control-oriented model applicable to a wide class of non-linear plants. It is a non-linear polynomial representation of the plant, which allows the use of well-established polynomial controller design methodologies. A learning rate parameter is introduced in the inverse finding computational algorithm in order to improve the convergence and stability properties. Computer simulation results and real-time experimental results are presented to show the effectiveness of the proposed method.
Investigation into the Effects of Shot Peening on the Fretting Fatigue Behaviour of 65Si7 Spring Steel Leaf Springs
Authors: Aggarwal M L , Khan R A , Agrawal V P
Published: October 2005

Leaf springs are subjected to varying stresses and vibrations due to road conditions. The influence of high contact pressures and temperatures follow fretting fatigue between two mating leaf surfaces. The work presented in this paper relates to improvement in fatigue and fretting fatigue performance of leaf springs using shot peening and coatings. The fatigue life of 65Si7 spring steel leaf springs has been determined experimentally at various shot peening conditions and optimum shot peening intensity is found. Full-scale leaf spring laboratory testing and specimen testing were carried out to show the extent of improvement in fatigue life as a result of shot peening. Structural damping is found to be an important surface characteristic of shot peened surfaces for reducing fretting fatigue. The effects of shot peening conditions and damping factor for minimizing fretting fatigue failures are discussed.
Monitoring of minimal residual disease in acute myeloid leukemia Monitorisierung minimaler Resterkrankung bei akuter myeloischer Leukämie
Authors: Kern Wolfgang , Schnittger Susanne
Published: October 2005

Monitoring minimal residual disease (MRD) becomes increasingly important in the risk-adapted management of patients with acute myeloid leukemia (AML). The two most sensitive and also quantitative methods for MRD detection are multiparameter flow cytometry (MFC) and real-time PCR (QRT-PCR). Fusion gene-specific PCR in AML is based on the RNA level while MFC evaluates MRD levels based on cell counts. Both methods have been demonstrated to independently impact the patients' prognosis. The strong power of MFC has been shown mainly in the assessment of early clearance of the malignant clone. MRD levels in AML with fusion genes have the strongest prognostic power after the end of consolidation therapy. In addition, with QRT-PCR, highly predictive initial expression levels can be assessed. With both methods, early detection of relapse is possible. Today, validated PCR-based MRD is being done not only with fusion genes that are detectable in only 20–25% of all AML, but also with new molecular markers like FLT3-mutations, NPM-mutations, MLL-PTD, WT1, and EVI1 expression. Thus, in 80–90% of all AML, a marker for PCR is available that can be detected with a sensitivity of 1:10,000 to 1:1,000,000. In contrast, MFC based MRD quantification is possible in nearly 100% of all AML. However, in some cases the sensitivity is somewhat lower than with PCR. Large clinical trials will determine the role and place of immunologic and PCR-based monitoring in the prognostic stratification of patients with AML.
Heterogeneity in physicochemical properties explains differences in silver toxicity amelioration by natural organic matter to Daphnia magna
Authors: Glover Chris N. , Sharma Sonia K. , Wood Chris M.
Published: October 2005

Recently collected data have shown that natural organic matter (NOM) source is an important parameter influencing the toxicity of silver to the freshwater crustacean Daphnia magna. The present study attempted to correlate the physicochemical properties of 11 naturally isolated and commercially available NOM sources with their ameliorative effects. The protection offered by these samples was standardized to the protective effect of Aldrich humic acid using geochemical modeling approaches that accounted for associated changes in water chemistry and, consequently, silver speciation. The protective ability of NOM was not correlated with reactive sulfide or nitrogen content, which are considered to be strong silver-binding ligands. Color (specific absorbance coefficient) was positively correlated with protection but narrowly eluded statistical significance. The peak wavelength of emission fluorescence following excitation at 370 nm and the fluorescence index values of NOM samples were significantly correlated with protective effects, suggesting that aromatic carbon content may govern the ameliorative actions of NOM. Simple optical properties may therefore act as a suitable indicator for the ability of a given NOM to protect against waterborne silver toxicity to D. magna as long as changes in water chemistry and, thus, silver speciation, are considered.
Enantiomeric fractions of chiral polychlorinated biphenyls provide insights on biotransformation capacity of arctic biota
Authors: Warner Nicholas A. , Norstrom Ross J. , Wong Charles S. , Fisk Aaron T.
Published: October 2005

Chiral polychlorinated biphenyls (PCBs) were measured in an arctic marine food web from the Northwater Polynya (NOW) in the Canadian Arctic to examine potential biotransformation of chiral PCB atropisomers. Organisms under investigation included pelagic zooplankton, Arctic cod (Boreogadus saida), seabirds, and ringed seals (Phoca hispida). Previous studies using achiral methods (e.g., biomagnification factors) have shown that chiral PCB congeners biomagnified in the NOW food web, but provided little information about biotransformation of PCBs except in extreme cases (i.e., high biotransformation). In this study, highly nonracemic enantiomeric fractions (EFs) were observed in several seabird species and ringed seals, but racemic EFs were found in prey (zooplankton and fish). This suggests stereoselective and species-specific biotransformation of individual PCB stereoisomers by birds and mammals. These results are consistent with previously reported biotransformation activity of chiral organochlorine pesticides, α-hexachlorocyclohexane, and chlordane within these organisms. This study demonstrates the utility of using chiral analysis of PCBs to investigate biotransformation within biota of arctic food webs.
Trihalomethane Formation Potential of Filter Isolates of Electrolyte‐Extractable Soil Organic Carbon
Authors: Chow Alex T. , Guo Fengmao , Gao Suduan , Breuer Richard S.
Published: October 2005

Certain organic C moieties of soil origin in drinking source waters of Sacramento–San Joaquin Delta (Delta) can react with chlorine to form trihalomethanes (THMs) during the disinfection process. Isolation and characterization of them and quantitation of their THM formation potential (THMFP) is necessary for developing effective strategies to reduce their influxes in Delta waters and for removing them during drinking water treatment. In this study, organic C from two Delta soils was extracted using deionized H2O and four Na‐ or Ca‐based electrolytes of varying electrical conductivity values. Extracts were filtered into particulate, colloidal, fine colloidal, and soluble organic C for quantitation and THMFP determination. Results suggested that <1.5% of soil organic C was electrolyte‐extractable. The soluble organic C fraction from both soils dominated in quantity and THMFP. Electrolyte effects were cation dependent. Sodium‐based electrolytes at either conductivity level did not significantly decrease extractable organic C (EOC) or THMFP compared with deionized H2O. In contrast, Ca‐based electrolytes reduced EOC and THMFP by >50% even at 1 dS m−1 Further increase in Ca concentration did not significantly decrease EOC or THMFP. Most reduction in EOC and THMFP by Ca‐based electrolytes occurred with the fractions other than the soluble organic C. Results suggested that under natural soil leaching and runoff conditions, the majority of THMFP is associated with organic C of <0.025 μm in diameter. Further molecular characterization of the fractions with high THMFP may help understand the nature of chlorine‐reactive organic C from Delta soils.
Manure Collection and Distribution on Wisconsin Dairy Farms
Authors: Powell J. Mark , McCrory Daniel F. , Jackson‐Smith D. B. , Saam H.
Published: October 2005

Manure management plans require knowing the amount of manure produced, collected, and available for land‐spreading. Whereas much information is available to calculate manure production, little is known about the types and amounts of manure actually collected on typical dairy farms. This study of 54 representative Wisconsin dairy farms showed significant regional, housing, and herd size differences in collection of manure from lactating cows (Bos taurus), dry cows, and heifers. Significantly (P < 0.05) less manure is collected in the hilly southwest (56% of total annual herd production) than in the undulating south central (72%) or the flat northeast (68%) regions. Collection of lactating cow manure is significantly (P < 0.05) lower from stanchion (66% of total annual production) than free‐stall (89%) housing, and significant (P < 0.05) positive relationships were found between the number of lactating cows a farm keeps and the percentage manure collected. Average annual manure N (range of 116–846 kg N ha−1) and P (range of 24–158 kg P ha−1) loading rates in areas where manure goes uncollected was highest in unvegetated barnyards followed by vegetated and partially vegetated outside areas. Once uncollected manure was accounted for, average annual loading rates on cereal cropland ranged from 128 to 337 kg ha−1 of manure N, and from 45 to 139 kg ha−1 of manure P. Compared with adjacent cropland, the accumulation of uncollected manure has vastly increased soil test P, K, and organic matter levels in outside areas. Manure management on Wisconsin dairy farms with small to medium herds might require assistance in managing manure in outside confinement areas to reduce the risk of impairing surface and ground water quality.
Antibacterial Activity of Soil‐Bound Antibiotics
Authors: Chander Yogesh , Kumar Kuldip , Goyal Sagar M. , Gupta Satish C.
Published: October 2005

There is some concern that antibiotic residues in land‐applied manure may promote the emergence of antibiotic resistant bacteria in the environment. The goal of this study was to determine whether or not soil bound antibiotics are still active against bacteria. The procedure involved sorbing various amounts of tetracycline or tylosin on two different textured soils (Webster clay loam [fine‐loamy, mixed, superactive, mesic Typic Endoaquolls] and Hubbard loamy sand [sandy, mixed, frigid Entic Hapludolls]), incubating these soils with three different bacterial cultures (an antibiotic resistant strain of Salmonella sp. [SalmonellaR], an antibiotic sensitive strain of Salmonella sp. [SalmonellaS], and Escherichia coli ATCC 25922), and then enumerating the number of colony forming units relative to the control. Incubation was done under both static and dynamic conditions. Soil‐adsorbed antibiotics were found to retain their antimicrobial properties since both antibiotics inhibited the growth of all three bacterial species. Averaged over all other factors, soil adsorbed antimicrobial activity was higher for Hubbard loamy sand than Webster clay loam, most likely due to higher affinity (higher clay content) of the Webster soil for antibiotics. Similarly, there was a greater decline in bacterial growth with tetracycline than tylsoin, likely due to greater amounts of soil‐adsorbed tetracycline and also due to lower minimum inhibitory concentration of most bacteria for tetracycline than tylosin. The antimicrobial effect of tetracycline was also greater under dynamic than static growth conditions, possibly because agitation under dynamic growth conditions helped increase tetracycline desorption and/or increase contact between soil adsorbed tetracycline and bacteria. We conclude that even though antibiotics are tightly adsorbed by clay particles, they are still biologically active and may influence the selection of antibiotic resistant bacteria in the terrestrial environment.
Effect of the applied organic load rate on biodegradable polymer production by mixed microbial cultures in a sequencing batch reactor
Authors: Dionisi Davide , Majone Mauro , Vallini Giovanni , Di Gregorio Simona , Beccari Mario
Published: October 2005

This article studies the operation of a new process for the production of biopolymers (polyhydroxyalkanoates, PHAs) at different applied organic load rates (OLRs). The process is based on the aerobic enrichment of activated sludge to obtain mixed cultures able to store PHAs at high rates and yields. A mixture of acetic, lactic, and propionic acids at different concentrations (in the range 8.5–31.25 gCOD/L) was fed every 2 h in a sequencing batch reactor (SBR). The resulting applied OLR was in the range 8.5–31.25 gCOD/L/day. Even though, as expected, the increase in the OLR caused an increase in biomass concentration (up to about 8.7 g COD/L), it also caused a relevant decrease of maximal polymer production rate. This decrease in polymer production rate was related to the different extent of “feast and famine” conditions, as function of the applied OLR and of the start‐up conditions. As a consequence the best performance of the process was obtained at an intermediate OLR (20 gCOD/L/day) where both biomass productivity and PHA storage were high enough. However, at this high OLR the process was unstable and sudden decrease of performance was also observed. The sludge characterized by the highest PHA storage response was investigated by 16S rDNA clone library. The clone library contained sequences mostly from PHA producers (e.g., Alcaligenes and Comamonas genera); however many genera and among them, one of the dominant (Thauera), were never described before in relation to PHA storage response. © 2005 Wiley Periodicals, Inc.
Enhancement of biomolecule transport by electroporation: A review of theory and practical application to transformation of Corynebacterium glutamicum
Authors: Tryfona Theodora , Bustard Mark T.
Published: October 2005

Selective and reversible permeabilization of the cell wall permeability barrier is the focus for many biotechnological applications. In this article, the basic principles for reversible membrane permeabilization, based on biological, chemical, and physical methods are reviewed. Emphasis is given to electroporation (electropermeabilization) which tends to be the most popular method for membrane permeabilization and for introduction of foreign molecules into the cells. The applications of this method in industrial processes as well as the critical factors and parameters which affect the success of this approach are discussed. The different strategies developed throughout the years for increased transformation efficiencies of the industrially important amino acid‐overproducing bacterium Corynebacterium glutamicum, are also summarized. © 2005 Wiley Periodicals, Inc.
Modeling evaluation of the fluid‐dynamic microenvironment in tissue‐engineered constructs: A micro‐CT based model
Authors: Cioffi Margherita , Boschetti Federica , Raimondi Manuela Teresa , Dubini Gabriele
Published: October 2005

Natural cartilage remodels both in vivo and in vitro in response to mechanical stresses, hence mechanical stimulation is believed to be a potential tool to modulate extra‐cellular matrix synthesis in tissue‐engineered cartilage. Fluid‐induced shear is known to enhance chondrogenesis in engineered cartilage constructs. The quantification of the hydrodynamic environment is a condition required to study the biochemical response to shear of 3D engineered cell systems. We developed a computational model of culture medium flow through the microstructure of a porous scaffold, during direct‐ perfused culture. The 3D solid model of the scaffold micro‐geometry was reconstructed from 250 micro‐computed tomography (micro‐CT) images. The results of the fluid dynamic simulations were analyzed at the central portions of the fluid domain, to avoid boundary effects. The average, median and mode shear stress values calculated at the scaffold walls were 3.48, 2.90, and 2.45 mPa respectively, at a flow rate of 0.5 cm3/min, perfused through a 15 mm diameter scaffold, at an inlet fluid velocity of 53 µm/s. These results were compared to results estimated using a simplified micro‐scale model and to results estimated using an analytical macro‐scale porous model. The predictions given by the CT‐based model are being used in conjunction with an experimental bioreactor model, in order to quantify the effects of fluid‐dynamic shear on the growth modulation of tissue‐engineered cartilage constructs, to potentially enhance tissue growth in vitro. © 2005 Wiley Periodicals, Inc.
Potent Inhibitors of LXXLL‐Based Protein–Protein Interactions
Authors: Galande Amit K. , Bramlett Kelli S. , Trent John O. , Burris Thomas P. , Wittliff James L. , Spatola Arno F.
Published: October 2005

Protein–protein interactions between estrogen receptors, ERα and ERβ, and their coactivators (CoAs) are an attractive target for drug intervention. This interaction is mediated by a small pentapeptide motif (LXXLL), termed the NR box. Based on this motif, a variety of cyclic and linear peptides were synthesized in order to gain a better understanding of the association of CoA proteins with the ER isoforms. Utilizing a time‐resolved florescence‐based coactivator interaction assay, we determined the abilities of these peptides to inhibit this interaction. Using molecular modeling and CD spectroscopy, we have examined the structural basis of their bioactivities with both hormone receptor isoforms. Either homocysteine or penicillamine was utilized as a substitute for cysteine in the disulfide‐bridged peptides, while tertiary leucine and neopentyl glycine were used as the surrogates for the NR box leucines. The most potent disufide‐bridged peptide (Ki= 70 pM, with ERα) incorporates neopentyl glycine in the NR box, while the most active peptide in this series with ERβ (Ki=350 pM) incorporates tertiary leucine. Surprisingly, several linear peptides containing a single cysteine residue showed activities with low nanomolar Ki values. Collectively, our results suggest a synthetic approach for designing potent and selective peptidomimetics for ERα and ERβ interactions with CoA proteins effecting estrogen action.
Recombinant Production of Human Microsomal Cytochrome P450 2D6 in the Methylotrophic Yeast Pichia pastoris
Authors: Dietrich Matthias , Grundmann Lisa , Kurr Katja , Valinotto Laura , Saussele Tanja , Schmid Rolf D. , Lange Stefan
Published: October 2005

Microsomal cytochrome P450 monooxygenases of groups 1–3 are mainly expressed in the liver and play a crucial role in phase 1 reactions of xenobiotic metabolism. The cDNAs encoding human CYP2D6 and human NADPH‐P450 oxidoreductase (CPR) were transformed into the methylotrophic yeast Pichia pastoris and expressed with control of the methanol‐inducible AOX1 promoter. The determined molecular weights of the recombinant CYP2D6 and CPR closely matched the calculated values of 55.8 and 76.6 kDa. CPR activity was detected by conversion of cytochrome c by using isolated microsomes. Nearly all of the recombinant CYP was composed of the active holoenzyme, as confirmed by reduced CO difference spectra, which showed a single peak at 450 nm. Only by coexpression of human CPR and CYP was CYP2D6 activity obtained. Microsomes containing human CPR and CYP2D6 converted different substrates, such as 3‐cyano‐7‐ethoxycoumarin, parathion and dextrometorphan. The kinetic parameters of dextrometorphan conversion closely matched those of CYP2D6 from other recombinant expression systems and human microsomes. The endogenous NADPH‐P450 oxidoreductase of Pichia pastoris seems to be incompatible with human CYP2D6, as expression of CYP2D6 without human CPR did not result in any CYP activity. These recombinant strains provide a novel, easy‐to‐handle and cheap source for the biochemical characterisation of single microsomal cytochromes, as well as their allelic variants.
Deamination of the Amino Acid Fragment in Imine Metallacycles: Unexpected Synthesis of an NH‐Aldimine Organometallic Compound
Authors: Albert Joan , Cadena J. Magali , González Asensio , Granell Jaume , Solans Xavier , Font‐Bardia Mercè
Published: October 2005

We report that the action of Lewis bases, such as triphenylphosphine, pyridine, or trimethylamine, on imine metallacycles derived from amino acids leads to the formation of the first organometallic compound of an NH aldimine, a highly reactive organic species, and the corresponding α‐ketoester, in a deamination reaction that mimics the metabolism of α‐amino acids. The synthesis of different cyclopalladated compounds by a reaction between palladium acetate and the Schiff bases 2,4,6‐Me3C6H2CHNCH(R1)COOR2 (R1=CH2Ph, R2=Et and R1=Ph, R2=Me) is also reported.
Nitrosation of Sugar Oximes: Preparation of 2‐Glycosyl‐1‐hydroxydiazene‐2‐oxides
Authors: Brand Jörg , Huhn Thomas , Groth Ulrich , Jochims Johannes C.
Published: October 2005

Oximes of glucose, xylose, lactose, fructose, and mannose have been prepared. Nitrosation of the oximes of glucose, xylose, and lactose with NaNO2/HCl afforded 2‐(β‐glycopyranosyl)‐1‐hydroxydiazene‐2‐oxides, which were isolated as salts 13, 22, and 28. Nitrosation of fructose oxime 29 furnished fructose, whereas nitrosation of mannose oxime 30 with NaNO2/HCl afforded the 1‐hydroxy‐2‐(β‐d‐mannopyranosyl)diazene‐2‐oxide 32, from which the p‐anisidinium salt 31 and the sodium salt 33 were prepared. However, nitrosation of 30 with isopentyl nitrite in aqueous solutions of CsOH or KOH resulted in the formation of the 2‐(α‐D‐mannofuranosyl)‐1‐hydroxydiazene‐2‐oxide salts 34 and 35, respectively. Methylation of the ammonium 2‐(β‐D‐glucopyranosyl)‐1‐hydroxydiazene‐2‐oxide 13 yielded the 1‐methoxy compound, which was benzoylated to afford the tetra‐O‐benzoate 14 a, the structure of which was confirmed by X‐ray diffraction analysis. From the glucose O‐methyloximes 15 and 16 the N‐methoxy‐N‐nitroso‐2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosylamine 18 was prepared. The structure of this compound was confirmed by X‐ray diffraction analysis. Treatment of acetobromoglucose with cupferron furnished the 1‐(2,3,4,6‐tetra‐O‐acetyl‐β‐D‐glucopyranosyloxy)‐2‐phenyldiazene‐2‐oxide 20.
On coordination and its significance to distributed and multi‐agent systems
Authors: Ossowski Sascha , Menezes Ronaldo
Published: October 2005

Coordination is one ofthosewords: it appears in most science and social fields, in politics, warfare, and it is even the subject of sports talks. While the usage of the word may convey different ideas to different people, the definition of coordination in all fields is quite similar—it relates to the control, planning, and execution of activities that are performed by distributed (perhaps independent) actors. Computer scientists involved in the field of distributed systems and agents focus on thedistributionaspect of this concept. They see coordination as a separate field from all the others—a field that rather complementsstandardfields such as the ones mentioned above. This paper focuses on explaining the term coordination in relation to distributed and multi‐agent systems. Several approaches to coordination are described and put in perspective. The paper finishes with a look at what we are callingemergent coordinationand its potential for efficiently handling coordination in open environments. Copyright © 2005 John Wiley & Sons, Ltd.
Variable Temperature Single‐Molecule Dynamics of MEH‐PPV
Authors: Lee Young Jong , Kim Doo Young , Grey John K. , Barbara Paul F.
Published: October 2005

Herein, we continue our investigation of the single‐molecule spectroscopy of the conjugated polymer poly[2‐methoxy,5‐(2′‐ethylhexyloxy)‐p‐phenylene‐vinylene] (MEH‐PPV) at cryogenic temperatures. First, the low temperature microsecond dynamics of single MEH‐PPV conjugated polymer molecules are compared to the dynamics at room temperature revealing no detectible temperature dependence. The lack of temperature dependence is consistent with the previous assignment of the dynamics to a mechanism that involves intersystem crossing and triplet–triplet annihilation. Second, the fluorescence spectra of single MEH‐PPV molecules at low temperature are studied as a function of excitation wavelength (i.e. 488, 543, and 568 nm). These results exhibit nearly identical fluorescence spectra for different excitation wavelengths. This strongly suggests that electronic energy transfer occurs efficiently to a small number of low‐energy sites in the multichromophoric MEH‐PPV chains.
Self‐Assembly of Organotin(IV) Moieties with the Schiff‐Base Ligands Pyruvic Acid Isonicotinyl Hydrazone and Pyruvic Acid Salicylhydrazone: Synthesis, Characterization, and Crystal Structures of Monomeric or Polymeric Complexes
Authors: Yin Handong , Hong Min , Xu Haolong , Gao Zhongjun , Li Gang , Wang Daqi
Published: October 2005

A series of organotin(IV) complexes of the type [R2SnLY]2or [R2SnL(R3SnOH)]2[L = 4‐NC5H4CON2C(CH3)CO2or 2‐HOC6H4CON2C(CH3)CO2, and Y = H2O or CH3OH] have been synthesized by the condensation reaction of R2SnO (R = Ph1,nC8H172) or R3SnCl (R =o‐ClBz3,o‐FBz4,p‐FBz5,p‐CNBz6) with the Schiff‐base ligand pyruvic acid isonicotinyl hydrazone in a 1:1 molar ratio or (R3Sn)2O (R =nBu7, Bz8,p‐CNBz9) or R3SnCl (R =o‐ClBz10,p‐ClBz11,p‐CNBz12) with the Schiff‐base ligand pyruvic acid salicylhydrazone in a 1:1 molar ratio. All complexes were characterized by elemental analysis and IR,1H, and119Sn NMR spectroscopy. The crystal structures of complexes1,2,3,7, and10have been determined by X‐ray single crystal diffraction analyses, which show that the tin atoms of1,2,3, and10are all seven‐coordinate in distorted pentagonal bipyramid geometries, of which only complex1exhibits an asymmetric structure containing two different types of tin atoms. The crystal structure of7exhibits a dimeric structure containing distannoxane units with two types of tin atoms, in which one tin atom appears to be seven‐coordinate with a distorted pentagonal bipyramid geometry and the other is four‐coordinate with a distorted tetrahedral geometry. A comparison of the IR spectra of the ligands with those of the corresponding complexes reveals that the ligands coordinate to tin in the enol form due to the disappearance of the bands assigned to the carbonyl group. (© Wiley‐VCH Verlag GmbH and Co. KGaA, 69451 Weinheim, Germany, 2005)
Synthetic, Structural, and Electrochemical Studies of 2‐Ferrocenyl‐ and2‐Cymantrenyl‐Functionalized 2,3‐Dihydro‐1H‐1,3,2‐diazaboroles and1,3,2‐Diazaborolidenes
Authors: Weber Lothar , Domke Imme , Stammler Hans‐Georg , Neumann Beate
Published: October 2005

Reaction of (dibromoboryl)ferrocene (1) with 1 equiv. of the diazabutadiene tBuN=CH–CH=NtBu, and subsequent reduction of the obtained borolium salt 2 with sodium amalgam, affords the first ferrocenyl‐functionalized 1,3,2‐diazaborole (3). Similarly, 1,1′‐bis(dibromoboryl)ferrocene (4) can be transformed into compound 6, which contains two diazaborolyl substituents at the ferrocene core. Treatment of precursors 1 and 4 with 1,2‐bis(tert‐butylamino)ethane in the presence of Et3N gives rise to the formation of the diazaborolidine derivatives 13 and 14. 1‐Dibromoboryl‐3‐methylcymantrene (7) was also treated with tBuN=CH–CH=NtBu to give the borolium salt 8, which was subsequently reduced to the 2‐cymantrenyl‐diazaborole 9. Treatment of 7 with tBuN(H)CH2CH2N(H)tBu in the presence of Et3N furnished the corresponding 2‐cymantrenyl‐diazaborolidine 15. The novel compounds were characterized by elemental analyses and various spectroscopic techniques (IR; 1H, 13C, and 11B NMR; MS). The molecular structures of 3, 6, and 15 were elucidated by X‐ray diffraction analyses. Cyclovoltammetric studies of the ferrocene derivatives at high scan rates show features of a quasireversible oxidation at the iron center. The heterocyclic groups serve as electron donors, considerably lowering the oxidation potential of the central iron atoms when compared to the parent compound ferrocene. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Significance of Intermolecular S···C(π) Interaction Involving M–S and –C=O Centers in Crystal Structures of Metal Thiolate Complexes
Authors: Lewiński Janusz , Bury Wojciech , Justyniak Iwona
Published: October 2005

The database analysis of intermolecular S···C(π) distances involving a metal‐bonded thiolate sulfur atom and various C(π)‐centered Lewis acid domains provided evidences for M–S···C(π) contacts as resulting from specific noncovalent interactions. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)