bluuebunny/crossref_metadata_2025 huggingface dataset:
Biofuel Cells Select for Microbial Consortia That Self-Mediate Electron Transfer
Authors: Rabaey Korneel , Boon Nico , Siciliano Steven D. , Verhaege Marc , Verstraete Willy
Published: September 2004

Microbial fuel cells hold great promise as a sustainable biotechnological solution to future energy needs. Current efforts to improve the efficiency of such fuel cells are limited by the lack of knowledge about the microbial ecology of these systems. The purposes of this study were (i) to elucidate whether a bacterial community, either suspended or attached to an electrode, can evolve in a microbial fuel cell to bring about higher power output, and (ii) to identify species responsible for the electricity generation. Enrichment by repeated transfer of a bacterial consortium harvested from the anode compartment of a biofuel cell in which glucose was used increased the output from an initial level of 0.6 W m−2of electrode surface to a maximal level of 4.31 W m−2(664 mV, 30.9 mA) when plain graphite electrodes were used. This result was obtained with an average loading rate of 1 g of glucose liter−1day−1and corresponded to 81% efficiency for electron transfer from glucose to electricity. Cyclic voltammetry indicated that the enhanced microbial consortium had either membrane-bound or excreted redox components that were not initially detected in the community. Dominant species of the enhanced culture were identified by denaturing gradient gel electrophoresis and culturing. The community consisted mainly of facultative anaerobic bacteria, such asAlcaligenes faecalisandEnterococcus gallinarum, which are capable of hydrogen production.Pseudomonas aeruginosaand otherPseudomonasspecies were also isolated. For several isolates, electrochemical activity was mainly due to excreted redox mediators, and one of these mediators, pyocyanin produced byP. aeruginosa, could be characterized. Overall, the enrichment procedure, irrespective of whether only attached or suspended bacteria were examined, selected for organisms capable of mediating the electron transfer either by direct bacterial transfer or by excretion of redox components.
Simultaneous Fluorescence In Situ Hybridization of mRNA and rRNA in Environmental Bacteria
Authors: Pernthaler Annelie , Amann Rudolf
Published: September 2004

We developed for
Bacteria
in environmental samples a sensitive and reliable mRNA fluorescence in situ hybridization (FISH) protocol that allows for simultaneous cell identification by rRNA FISH. Samples were carbethoxylated with diethylpyrocarbonate to inactivate intracellular RNases and pretreated with lysozyme and/or proteinase K at different concentrations. Optimizing the permeabilization of each type of sample proved to be a critical step in avoiding false-negative or false-positive results. The quality of probes as well as a stringent hybridization temperature were determined with expression clones. To increase the sensitivity of mRNA FISH, long ribonucleotide probes were labeled at a high density with
cis
-platinum-linked digoxigenin (DIG). The hybrid was immunocytochemically detected with an anti-DIG antibody labeled with horseradish peroxidase (HRP). Subsequently, the hybridization signal was amplified by catalyzed reporter deposition with fluorochrome-labeled tyramides.
p
-Iodophenylboronic acid and high concentrations of NaCl substantially enhanced the deposition of tyramides and thus increased the sensitivity of our approach. After inactivation of the antibody-delivered HRP, rRNA FISH was performed by following routine protocols. To show the broad applicability of our approach, mRNA of a key enzyme of aerobic methane oxidation, particulate methane monooxygenase (subunit A), was hybridized with different types of samples: pure cultures, symbionts of a hydrothermal vent bivalve, and even sediment, one of the most difficult sample types with which to perform successful FISH. By simultaneous mRNA FISH and rRNA FISH, single cells are identified and shown to express a particular gene. Our protocol is transferable to many different types of samples with the need for only minor modifications of fixation and permeabilization procedures.
Identification of Members of the Metabolically Active Microbial Populations Associated with
Beggiatoa
Species Mat Communities from Gulf of Mexico Cold-Seep Sediments
Authors: Mills Heath J. , Martinez Robert J. , Story Sandra , Sobecky Patricia A.
Published: September 2004

In this study, the composition of the metabolically active fraction of the microbial community occurring in Gulf of Mexico marine sediments (water depth, 550 to 575 m) with overlying filamentous bacterial mats was determined. The mats were mainly composed of either orange- or white-pigmented
Beggiatoa
spp. Complementary 16S ribosomal DNA (crDNA) was obtained from rRNA extracted from three different sediment depths (0 to 2, 6 to 8, and 10 to 12 cm) that had been subjected to reverse transcription-PCR amplification. Domain-specific 16S PCR primers were used to construct 12 different 16S crDNA libraries containing 333
Archaea
and 329
Bacteria
clones. Analysis of the
Archaea
clones indicated that all sediment depths associated with overlying orange- and white-pigmented microbial mats were almost exclusively dominated by ANME-2 (95% of total
Archaea
clones), a lineage related to the methanogenic order
Methanosarcinales
. In contrast, bacterial diversity was considerably higher, with the dominant phylotype varying by sediment depth. An equivalent number of clones detected at 0 to 2 cm, representing a total of 93%, were related to the γ and δ classes of
Proteobacteria
, whereas clones related to δ-
Proteobacteria
dominated the metabolically active fraction of the bacterial community occurring at 6 to 8 cm (79%) and 10 to 12 cm (85%). This is the first phylogenetics-based evaluation of the presumptive metabolically active fraction of the
Bacteria
and
Archaea
community structure investigated along a sediment depth profile in the northern Gulf of Mexico, a hydrocarbon-rich cold-seep region.
Experimental and Theoretical Bases of Specific Affinity, a Cytoarchitecture-Based Formulation of Nutrient Collection Proposed To Supercede the Michaelis-Menten Paradigm of Microbial Kinetics
Authors: Button D. K. , Robertson Betsy , Gustafson Elizabeth , Zhao Xiaoming
Published: September 2004

A theory for solute uptake by whole cells was derived with a focus on the ability of oligobacteria to sequester nutrients. It provided a general relationship that was used to obtain the kinetic constants for in situ marine populations in the presence of naturally occurring substrates. In situ affinities of 0.9 to 400 liters g of cells
−1
h
−1
found were up to 10
3
times smaller than those from a “
Marinobacter arcticus
” isolate, but springtime values were greatly increased by warming. Affinities of the isolate for usual polar substrates but not for hydrocarbons were diminished by ionophores. A kinetic curve or Monod plot was constructed from the best available data for cytoarchitectural components of the isolate by using the theory together with concepts and calculations from first principles. The order of effect of these components on specific affinity was membrane potential > cytoplasmic enzyme concentration > cytoplasmic enzyme affinity > permease concentration > area of the permease site > translation coefficient > porin concentration. Component balance was influential as well; a small increase in cytoplasmic enzyme concentration gave a large increase in the effect of permease concentration. The effect of permease concentration on specific affinity was large, while the effect on

K
m

was small. These results are in contrast to the Michaelis-Menten theory as applied by Monod that has uptake kinetics dependent on the quality of the permease molecules, with

K
m

as an independent measure of affinity. Calculations demonstrated that most oligobacteria in the environment must use multiple substrates simultaneously to attain sufficient energy and material for growth, a requirement consistent with communities largely comprising few species.
Blakeslea trispora
Genes for Carotene Biosynthesis
Authors: Rodríguez-Sáiz M. , Paz B. , de la Fuente J. L. , López-Nieto M. J. , Cabri W. , Barredo J. L.
Published: September 2004

We cloned the
carB
and
carRA
genes involved in β-carotene biosynthesis from overproducing and wild-type strains of
Blakeslea trispora
. The
carB
gene has a length of 1,955 bp, including two introns of 141 and 68 bp, and encodes a protein of 66.4 kDa with phytoene dehydrogenase activity. The
carRA
gene contains 1,894 bp, with a single intron of 70 bp, and encodes a protein of 69.6 kDa with separate domains for lycopene cyclase and phytoene synthase. The estimated transcript sizes for
carB
and
carRA
were 1.8 and 1.9 kb, respectively. CarB from the β-carotene-overproducing strain
B. trispora
F-744 had an S528R mutation and a TAG instead of a TAA stop codon. The overproducing strain also had a P143S mutation in CarRA. Both
B. trispora
genes could complement mutations in orthologous genes in
Mucor circinelloides
and could be used to construct transformed strains of
M. circinelloides
that produced higher levels of β-carotene than did the nontransformed parent. The results show that these genes are conserved across the zygomycetes and that the
B. trispora carB
and
carRA
genes are functional and potentially useable to increase carotenoid production.
Cloning and Characterization of the Bile Salt Hydrolase Genes (
bsh
) from
Bifidobacterium bifidum
Strains
Authors: Kim Geun-Bae , Miyamoto Carol M. , Meighen Edward A. , Lee Byong H.
Published: September 2004

Biochemical characterization of the purified bile salt hydrolase (BSH) from
Bifidobacterium bifidum
ATCC 11863 revealed some distinct characteristics not observed in other species of
Bifidobacterium
. The
bsh
gene was cloned from
B. bifidum
, and the DNA flanking the
bsh
gene was sequenced. Comparison of the deduced amino acid sequence of the cloned gene with previously known sequences revealed high homology with BSH enzymes from several microorganisms and penicillin V amidase (PVA) of
Bacillus sphaericus
. The proposed active sites of PVA were highly conserved, including that of the Cys-1 residue. The importance of the SH group in the N-terminal cysteine was confirmed by substitution of Cys with chemically and structurally similar residues, Ser or Thr, both of which resulted in an inactive enzyme. The transcriptional start point of the
bsh
gene has been determined by primer extension analysis. Unlike
Bifidobacterium longum bsh
,
B. bifidum bsh
was transcribed as a monocistronic unit, which was confirmed by Northern blot analysis. PCR amplification with the type-specific primer set revealed the high level of sequence homology in their
bsh
genes within the species of
B. bifidum
.
Implications of Amino Acid Substitutions in GyrA at Position 83 in Terms of Oxolinic Acid Resistance in Field Isolates ofBurkholderia glumae, a Causal Agent of Bacterial Seedling Rot and Grain Rot of Rice
Authors: Maeda Yukiko , Kiba Akinori , Ohnishi Kouhei , Hikichi Yasufumi
Published: September 2004

Oxolinic acid (OA), a quinolone, inhibits the activity of DNA gyrase composed of GyrA and GyrB and shows antibacterial activity againstBurkholderia glumae. SinceB. glumaecauses bacterial seedling rot and grain rot of rice, both of which are devastating diseases, the emergence of OA-resistant bacteria has important implications on rice cultivation in Japan. Based on the MIC of OA, 35B. glumaefield isolates isolated from rice seedlings grown from OA-treated seeds in Japan were divided into sensitive isolates (OSs; 0.5 μg/ml), moderately resistant isolates (MRs; 50 μg/ml), and highly resistant isolates (HRs; ≥100 μg/ml). Recombination withgyrAof an OS, Pg-10, led MRs and HRs to become OA susceptible, suggesting thatgyrAmutations are involved in the OA resistance of field isolates. The amino acid at position 83 in the GyrA of all OSs was Ser, but in all MRs and HRs it was Arg and Ile, respectively. Ser83Arg and Ser83Ile substitutions in the GyrA of an OS, Pg-10, resulted in moderate and high OA resistance, respectively. Moreover, Arg83Ser and Ile83Ser substitutions in the GyrA of MRs and HRs, respectively, resulted in susceptibility to OA. These results suggest that Ser83Arg and Ser83Ile substitutions in GyrA are commonly responsible for resistance to OA inB. glumaefield isolates.
Identification and Functional Characterization of a
Xenorhabdus nematophila
Oligopeptide Permease
Authors: Orchard Samantha S. , Goodrich-Blair Heidi
Published: September 2004

The bacterium
Xenorhabdus nematophila
is a mutualist of
Steinernema carpocapsae
nematodes and a pathogen of insects. Presently, it is not known what nutrients the bacterium uses to thrive in these host environments. In other symbiotic bacteria, oligopeptide permeases have been shown to be important in host interactions, and we therefore sought to determine if oligopeptide uptake is essential for growth or symbiotic functions of
X. nematophila
in laboratory or host environments. We identified an
X. nematophila
oligopeptide permease (
opp
) operon of two sequential
oppA
genes, predicted to encode oligopeptide-binding proteins, and putative permease-encoding genes
oppB
,
oppC
,
oppD
, and
oppF
. Peptide-feeding studies indicated that this
opp
operon encodes a functional oligopeptide permease. We constructed strains with mutations in
oppA
1
,
oppA
2
, or
oppB
and examined the ability of each mutant strain to grow in a peptide-rich laboratory medium and to interact with the two hosts. We found that the
opp
mutant strains had altered growth phenotypes in the laboratory medium and in hemolymph isolated from larval insects. However, the
opp
mutant strains were capable of initiating and maintaining both mutualistic and pathogenic host interactions. These data demonstrate that the
opp
genes allow
X. nematophila
to utilize peptides as a nutrient source but that this function is not essential for the existence of
X. nematophila
in either of its host niches. To our knowledge, this study represents the first experimental analysis of the role of oligopeptide transport in mediating a mutualistic invertebrate-bacterium interaction.
Molecular Fingerprinting of Dairy Microbial Ecosystems by Use of Temporal Temperature and Denaturing Gradient Gel Electrophoresis
Authors: Ogier J.-C. , Lafarge V. , Girard V. , Rault A. , Maladen V. , Gruss A. , Leveau J.-Y. , Delacroix-Buchet A.
Published: September 2004

Numerous microorganisms, including bacteria, yeasts, and molds, constitute the complex ecosystem present in milk and fermented dairy products. Our aim was to describe the bacterial ecosystem of various cheeses that differ by production technology and therefore by their bacterial content. For this purpose, we developed a rapid, semisystematic approach based on genetic profiling by temporal temperature gradient electrophoresis (TTGE) for bacteria with low-G+C-content genomes and denaturing gradient gel electrophoresis (DGGE) for those with medium- and high-G+C-content genomes. Bacteria in the unknown ecosystems were assigned an identity by comparison with a comprehensive bacterial reference database of ∼150 species that included useful dairy microorganisms (lactic acid bacteria), spoilage bacteria (e.g.,
Pseudomonas
and
Enterobacteriaceae
), and pathogenic bacteria (e.g.,
Listeria monocytogenes
and
Staphylococcus aureus
). Our analyses provide a high resolution of bacteria comprising the ecosystems of different commercial cheeses and identify species that could not be discerned by conventional methods; at least two species, belonging to the
Halomonas
and
Pseudoalteromonas
genera, are identified for the first time in a dairy ecosystem. Our analyses also reveal a surprising difference in ecosystems of the cheese surface versus those of the interior; the aerobic surface bacteria are generally G+C rich and represent diverse species, while the cheese interior comprises fewer species that are generally low in G+C content. TTGE and DGGE have proven here to be powerful methods to rapidly identify a broad range of bacterial species within dairy products.
Effect of
Escherichia coli
Morphogene
bolA
on Biofilms
Authors: Vieira Helena L. A. , Freire Patrick , Arraiano Cecília M.
Published: September 2004

Biofilm physiology is established under a low growth rate. The morphogene
bolA
is mostly expressed under stress conditions or in stationary phase, suggesting that
bolA
could be implicated in biofilm development. In order to verify this hypothesis, we tested the effect of
bolA
on biofilm formation. Overexpression of
bolA
induces biofilm development, while
bolA
deletion decreases biofilms.
Methanogenic Inhibition by Arsenic Compounds
Authors: Sierra-Alvarez Reyes , Cortinas Irail , Yenal Umur , Field Jim A.
Published: September 2004

The acute acetoclastic methanogenic inhibition of several inorganic and organic arsenicals was assayed. Trivalent species, i.e., methylarsonous acid and arsenite, were highly inhibitory, with 50% inhibitory concentrations of 9.1 and 15.0 μM, respectively, whereas pentavalent species were generally nontoxic. The nitrophenylarsonate derivate, roxarsone, displayed moderate toxicity.
Widespread Occurrence of a Novel Division of Bacteria Identified by 16S rRNA Gene Sequences Originally Found in Deep Marine Sediments
Authors: Webster Gordon , Parkes R. John , Fry John C. , Weightman Andrew J.
Published: September 2004

Phylogenetic analysis of 16S rRNA gene sequences from deep marine sediments identified a deeply branching clade, designated candidate division JS1. Primers for PCR amplification of partial 16S rRNA genes that target the JS1 division were developed and used to detect JS1 sequences in DNA extracted from various sedimentary environments, including, for the first time, coastal marine and brackish sediments.
Synergistic amplification of β-amyloid- and interferon-γ-induced microglial neurotoxic response by the senile plaque component chromogranin A
Authors: Twig Gilad , Graf Solomon A. , Messerli Mark A. , Smith Peter J. S. , Yoo Seung H. , Shirihai Orian S.
Published: September 2004

Activation of the microglial neurotoxic response by components of the senile plaque plays a critical role in the pathophysiology of Alzheimer's disease (AD). Microglia induce neurodegeneration primarily by secreting nitric oxide (NO), tumor necrosis factor-α (TNFα), and hydrogen peroxide. Central to the activation of microglia is the membrane receptor CD40, which is the target of costimulators such as interferon-γ (IFNγ). Chromogranin A (CGA) is a recently identified endogenous component of the neurodegenerative plaques of AD and Parkinson's disease. CGA stimulates microglial secretion of NO and TNFα, resulting in both neuronal and microglial apoptosis. Using electrochemical recording from primary rat microglial cells in culture, we have shown in the present study that CGA alone induces a fast-initiating oxidative burst in microglia. We compared the potency of CGA with that of β-amyloid (βΑ) under identical conditions and found that CGA induces 5–7 times greater NO and TNFα secretion. Coapplication of CGA with βΑ or with IFNγ resulted in a synergistic effect on NO and TNFα secretion. CD40 expression was induced by CGA and was further increased when βΑ or IFNγ was added in combination. Tyrphostin A1 (TyrA1), which inhibits the CD40 cascade, exerted a dose-dependent inhibition of the CGA effect alone and in combination with IFNγ and βΑ. Furthermore, CGA-induced mitochondrial depolarization, which precedes microglial apoptosis, was fully blocked in the presence of TyrA1. Our results demonstrate the involvement of CGA with other components of the senile plaque and raise the possibility that a narrowly acting agent such as TyrA1 attenuates plaque formation.
Angiotensin II-induced hypertrophy is potentiated in mice overexpressing p22phox in vascular smooth muscle
Authors: Weber David S. , Rocic Petra , Mellis Adamantios M. , Laude Karine , Lyle Alicia N. , Harrison David G. , Griendling Kathy K.
Published: September 2004

Increased reactive oxygen species (ROS) are implicated in several vascular pathologies associated with vascular smooth muscle hypertrophy. In the current studies, we utilized transgenic (Tg) mice (Tg p22smc) that overexpress the p22 phox subunit of NAD(P)H oxidase selectively in smooth muscle. These mice have a twofold increase in aortic p22 phox expression and H2O2 production and thus provide an excellent in vivo model in which to assess the effects of increased ROS generation on vascular smooth muscle cell (VSMC) function. We tested the hypothesis that overexpression of VSMC p22 phox potentiates angiotensin II (ANG II)-induced vascular hypertrophy. Male Tg p22smc mice and negative littermate controls were infused with either ANG II or saline for 13 days. Baseline blood pressure was not different between control and Tg p22smc mice. ANG II significantly increased blood pressure in both groups, with this increase being slightly exacerbated in the Tg p22smc mice. Baseline aortic wall thickness and cross-sectional wall area were not different between control and Tg p22smc mice. Importantly, the ANG II-induced increase in both parameters was significantly greater in the Tg p22smc mice compared with control mice. To confirm that this potentiation of vascular hypertrophy was due to increased ROS levels, additional groups of mice were coinfused with ebselen. This treatment prevented the exacerbation of hypertrophy in Tg p22smc mice receiving ANG II. These data suggest that although increased availability of NAD(P)H oxidase-derived ROS is not a sufficient stimulus for hypertrophy, it does potentiate ANG II-induced vascular hypertrophy, making ROS an excellent target for intervention aimed at reducing medial thickening in vivo.
Extracellular Ca2+regulates the stimulation of Na+transport in A6 renal epithelia
Authors: Jans Danny , Simaels Jeannine , Larivière Els , Steels Paul , Van Driessche Willy
Published: September 2004

We investigated the involvement of intracellular and extracellular Ca2+in the stimulation of Na+transport during hyposmotic treatment of A6 renal epithelia. A sudden osmotic decrease elicits a biphasic stimulation of Na+transport, recorded as increase in amiloride-sensitive short-circuit current ( Isc) from 3.4 ± 0.4 to 24.0 ± 1.3 μA/cm2( n = 6). Changes in intracellular Ca2+concentration ([Ca2+]i) were prevented by blocking basolateral Ca2+entry with Mg2+and emptying the intracellular Ca2+stores before the hyposmotic challenge. This treatment did not noticeably affect the hypotonicity-induced stimulation of Isc. However, the absence of extracellular Ca2+severely attenuated Na+transport stimulation by the hyposmotic shock, and Iscmerely increased from 2.2 ± 0.3 to 4.8 ± 0.7 μA/cm2. Interestingly, several agonists of the Ca2+-sensing receptor, Mg2+(2 mM), Gd3+(0.1 mM), neomycin (0.1 mM), and spermine (1 mM) were able to substitute for extracellular Ca2+. When added to the basolateral solution, these agents restored the stimulatory effect of the hyposmotic solutions on Iscin the absence of extracellular Ca2+to levels that were comparable to control conditions. None of the above-mentioned agonists induced a change in [Ca2+]i. Quinacrine, an inhibitor of PLA2, overruled the effect of the agonists on Na+transport. In conclusion, we suggest that a Ca2+-sensing receptor in A6 epithelia mediates the stimulation of Na+transport without the interference of changes in [Ca2+]i.
Effect of muscimol and l-NAME in the PVN on the RSNA response to volume expansion in conscious rabbits
Authors: Ng Chi Wai , De Matteo Robert , Badoer Emilio
Published: September 2004

In the present study, we have investigated whether the hypothalamic paraventricular nucleus (PVN) contributed to the reflex reduction in renal sympathetic nerve activity (RSNA) normally elicited by volume expansion in the conscious rabbit. RSNA was monitored after volume expansion (Dextran 70, 2 ml/min for 30 min) in animals microinjected into, and outside, the PVN with muscimol (10 nmol), to acutely inhibit neuronal function. Because nitric oxide within the PVN inhibits RSNA, we also examined the effect of NG-nitro-l-arginine methyl ester (l-NAME; 20 nmol) to block nitric oxide synthase. Compared with vehicle, the reduction in RSNA elicited by volume expansion was abolished by injection of muscimol into the PVN. The effect was specific to the PVN because microinjections of muscimol outside the PVN had no effect on the response. l-NAME microinjected into or outside the PVN had no effect on the RSNA response. The findings suggest that the PVN is essential in the central pathways mediating the renal sympathetic nerve response elicited by elevations in plasma volume but that nitric oxide does not play a major role.
Kinematic and Kinetic Constraints on Arm, Trunk, and Leg Segments in Target-Reaching Movements
Authors: Thomas James S. , Corcos Daniel M. , Hasan Ziaul
Published: September 2004

We studied target reaching tasks involving not only the arms but also the trunk and legs, which necessitated some trunk flexion. Such tasks can be successfully completed using an infinite number of combinations of segment motions due to the inherent kinematic redundancy with the excessive degrees of freedom (DOFs). Sagittal plane motions of six segments (shank, thigh, pelvis, trunk, humerus, and forearm) and dynamic torques of six joints (ankle, knee, hip, lumbar, shoulder, and elbow) were analyzed separately by principal component (PC) analyses to determine if there was a commonality among the shapes of the respective waveforms. Additionally, PC analyses were used to probe for constraining relationships among the 1) relative magnitudes of segment excursions and 2) the peak-to-peak dynamic joint torques. In summary, at the kinematic level, the tasks are simplified by the use of a single common waveform for all segment excursions with 89.9% variance accounted for (VAF), but with less fixed relationships among the relative scaling of the magnitude of segment excursions (62.2% VAF). However, at the kinetic level, the time course of the dynamic joint torques are not well captured by a single waveform (72.7% VAF), but the tasks are simplified by relatively fixed relationships among the scaling of dynamic joint torque magnitudes across task conditions (94.7% VAF). Taken together, these results indicate that, while the effective DOFs in a multi-joint task are reduced differently at the kinematic and kinetic levels, they both contribute to simplifying the neural control of these tasks.
A Limited Set of Muscle Synergies for Force Control During a Postural Task
Authors: Ting Lena H. , Macpherson Jane M.
Published: September 2004

Recently developed computational techniques have been used to reduce muscle activation patterns of high complexity to a simple synergy organization and to bring new insights to the long-standing degrees of freedom problem in motor control. We used a nonnegative factorization approach to identify muscle synergies during postural responses in the cat and to examine the functional significance of such synergies for natural behaviors. We hypothesized that the simplification of neural control afforded by muscle synergies must be matched by a similar reduction in degrees of freedom at the biomechanical level. Electromyographic data were recorded from 8–15 hindlimb muscles of cats exposed to 16 directions of support surface translation. Results showed that as few as four synergies could account for >95% of the automatic postural response across all muscles and all directions. Each synergy was activated for a specific set of perturbation directions, and moreover, each was correlated with a unique vector of endpoint force under the limb. We suggest that, within the context of active balance control, postural synergies reflect a neural command signal that specifies endpoint force of a limb.
The Two Faces of Wisdom: Wisdom as a General Theory of Knowledge and Judgment about Excellence in Mind and Virtue vs. Wisdom as Everyday Realization in People and Products
Authors: Baltes Paul B. , Kunzmann Ute
Published: September 2004

There are several legitimate ways of conceptualizing and studying wisdom. One is largely informed by Western philosophy and treats wisdom as an analytic theory of expert knowledge, judgment, and advice about difficult and uncertain matters of life. Another is more consistent with Asian philosophical non-secularized traditions and treats wisdom as instantiated by wise persons or their products. The second approach is always but an approximation to the analytically constructed utopia of wisdom. Wise persons are approximations to wisdom, but they are not wisdom. Ardelt’s critique of our work proposes that our theoretical conception of wisdom as a body of expert knowledge in a specific subject matter is similar to ‘cold’ cognition. We disagree and assert that our conception of wisdom includes as antecedents, correlates, and consequences a rich spectrum of specific cognitive, emotional, motivational and social factors as well as life contexts. Our empirical research unequivocally supports this multidimensional and collaborative view.
Aortic Valve Stenosis: Fatal Natural History despite Normal Left Ventricular Function and Low Invasive Peak-to-Peak Pressure Gradients
Authors: Lodberg Christensen Kent , Ivarsen Hanne Ramløv , Thuesen Leif , Kristensen Bent Østergaard , Egeblad Henrik
Published: September 2004

For many years, the severity of valvular aortic stenosis (AS) was evaluated mainly on the basis of cardiac catheterization. In many centers, the handy peak-to-peak transvalvular pressure difference or ‘peak-to-peak gradient’ in relation to left ventricular function was used as a crucial feature in taking a decision regarding valve substitution. In a prospective study during the period 1994–1997, 150 consecutive patients with AS were examined systematically using cardiac catherization as well as transthoracic (TTE) and transesophageal echocardiography. The study was performed in order to compare the diagnostic accuracy and reproducibility of the three modalities with the purpose of improving our evaluation strategy. We found that the three methods were able to determine the aortic valve area with similar accuracy and reproducibility. The data thus support earlier papers and the currently recommended strategy of managing most patients on the basis of TTE since this approach is more rapid and gentle to the patients. In accordance with the past policy of our department, however, considerable weight was put on the invasive data during the study period. Thus, 12 patients with invasive peak-to-peak gradient <50 mm Hg and no severe depression of left ventricular function were not offered valve replacement, despite symptoms and significant valve area reductions. At 2.5 years of follow-up, 6 had died, 3 of severe heart failure, 2 while awaiting scheduled valve replacement, and 1 during aortocoronary bypass surgery. Another 3 patients later experienced further symptom progression and underwent successful aortic valve replacement. In the remaining 3 patients, all free from coronary stenoses and other valvular heart disease than AS, heart failure symptoms had worsened considerably during continued medical therapy. In conclusion, we do not recommend consideration of the peak-to-peak gradient in the process of deciding whether or not AS patients should receive valve replacement. A low peak-to-peak gradient does not exclude severe AS, even in the presence of preserved left ventricular function.
Tolerability of β-Blocker Initiation and Titration with Bisoprolol and Carvedilol in Congestive Heart Failure – A Randomized Comparison
Authors: Galatius Søren , Gustafsson Finn , Atar Dan , Hildebrandt Per R.
Published: September 2004

In clinical trials β-blockers (BB) are well tolerated in patients with systolic congestive heart failure (CHF). In contrast, in daily practice treatment initiation and titration appear to be more difficult and may differ in various BB – but systematic data are lacking. We randomized 87 patients with systolic CHF (mean age 70.1 ± 10.6 years, 24% females, LVEF 0.28 ± 0.10, NYHA III-IV 29%) to treatment with either bisoprolol or carvedilol, in order to assess and compare the maximally achievable number of patients on treatment with these BB and the maximally achieved dosage during a minimum of 2 months attendance at our out patient heart failure clinic. In those randomized to bisoprolol, mean dose at 2 months was 33% of target dose (3.1 ± 2.6 mg ) and 41% at discharge. In those on carvedilol, the mean dose at 2 months was 27% of target dose (13.4 ± 14.0 mg) and 32% at discharge. Thirty-nine and 40% of the bisoprolol and carvedilol treated patients, respectively, had stopped treatment at discharge. None of the figures differed significantly between the two treatment groups and no baseline parameter predicted BB tolerability. Thus, almost twice the number of unselected patients with systolic CHF attending a heart failure clinic focusing on systematic medical titration were intolerant to BB treatment and only a minority reached target dose treatment. The present data reveal no clear difference with respect to tolerability of carvedilol and bisoprolol, and no parameter predicts tolerability.
Should We Continue Performing Intrauterine Inseminations in the Year 2004?
Authors: Cohlen B.J.
Published: September 2004

This review summarizes the existing evidence regarding intrauterine insemination (IUI) as a treatment for cervical hostility, male and unexplained subfertility. IUI in natural cycles has been proven effective in patients with cervical hostility and moderate male subfertility. IUI in cycles with mild ovarian hyperstimulation (MOH) should be the treatment of choice in couples with mild male subfertilty (average total motile sperm count above 10 million) and unexplained subfertilty. When MOH is applied, gonadotropins have been proven more effective compared with clomiphene citrate. Further large trials comparing clomiphene citrate with gonadotropins are mandatory. Prevention of multiple pregnancies in MOH/IUI programs is of paramount importance. A strategy with a low-dose step-up protocol and strict cancellation criteria is proposed. When multiple pregnancies are kept to a minimum, MOH/IUI is more cost-effective compared with in vitro fertilization and embryo transfer. Future research should focus on prediction models to predict the outcome of MOH/IUI treatment for individual couples before starting treatment.
Neurotransmitters Involved in the Opioid Regulation of Prolactin Secretion at the End of Pregnancy in Rats
Authors: Soaje Marta , Bregonzio Claudia , Carón Rubén W. , Deis Ricardo P.
Published: September 2004

Using a pharmacological approach, we explored potential mechanisms for the regulation of prolactin secretion by opioid peptides at the end of pregnancy in rats. On day 19 of pregnancy, intracereboventricular administration of the µ-opioid receptor agonist (D-Ala2, NMe-Phe4, Gly-ol5)-enkephalin (DAMGO) or β-endorphin (β-END) induced a dose-related increase in serum prolactin levels 30 min later. Pretreatment with the opioid antagonist naloxone abolished the increase induced by DAMGO injection. At lower doses, DAMGO and β-END did not modify the 3,4-dihydroxyphenylacetic acid/dopamine ratio, but at higher doses, the µ-agonists evoked a significant increase of the dopaminergic activity as compared with saline control. The time course of the effects of β-END (2.5 µg/rat) showed a higher increase in serum prolactin levels at 15 min than at 30 min after treatment. The 3,4-dihydroxyphenylacetic acid/dopamine ratio increased 15 min after β-END administration and was even higher 30 min later. Neither the selective ĸ-agonist U50,488H nor the selective δ-agonist (D-Pen2, D-Pen5)- enkephalin were able to modify the serum prolactin levels at the doses studied.To evaluate potential neurotransmitters involved in the regulation of prolactin secretion at the end of pregnancy, we combined the administration of serotoninergic or GABAergic antagonists with the opioid agonist DAMGO. The serotonin 5-HT2 receptor antagonist ketanserin increased the serum prolactin levels and potentiated the effect of DAMGO. The intracerebroventricular administration of SR-95531 did not modify the serum prolactin concentration under basal conditions, but partially prevented the increase induced by DAMGO injection. The intracerebroventricular administration of the GABAB receptor antagonist phaclofen had no effect on the serum prolactin levels either in naive or DAMGO-treated rats. The present results support the proposal that activation of µ-opioid receptors stimulates prolactin secretion at the end of pregnancy. Although the exact mechanisms by which the opioid system modulates prolactin secretion at the end of pregnancy are unclear, these results suggest an interaction of the opioidergic system with serotoninergic and GABAergic systems, without ruling out a direct or indirect action on dopaminergic neurons. In conclusion, the opioid system may regulate prolactin secretion at the end of pregnancy through either stimulatory (present results) or inhibitory actions previously described.
Functional Expression of Sodium-Dependent Vitamin C Transporter 2 in Human Endothelial Cells
Authors: Seno Tadashi , Inoue Nobutaka , Matsui Kiyoko , Ejiri Junya , Hirata Ken-ichi , Kawashima Seinosuke , Yokoyama Mitsuhiro
Published: September 2004

Since oxidative stress plays an important role in dysregulation of the microcirculation as well as the pathogenesis of atherosclersosis, therapeutic intervention with antioxidants has been speculated to prevent cardiovascular diseases. Ascorbic acid (AA) has been reported to improve endothelial function; however, its intracellular metabolic pathway has not been fully determined. Sodium-dependent vitamin C transporter (SVCT) types 1 and 2 were recently cloned. In the present study, we investigated whether SVCT-2 is functionally expressed in vascular endothelial cells and, if so, what factors modulate its activity. The uptake of AA into human umbilical vein endothelial cells (HUVECs) was examined by incubation with radiolabeled AA (14C-AA). AA was transported into HUVECs in a dose- and time-dependent manner. Replacement of sodium chloride with choline chloride in the medium suppressed the uptake of AA. RT-PCR revealed that HUVECs expressed SVCT-2 mRNA, but not SVCT-1. Transfection of HUVECs with the antisense oligonucleotide of SVCT-2 significantly suppressed the uptake of AA. Furthermore, tumor necrosis factor-α and interleukin-1β inhibited the transport activity of AA. Thus, SVCT-2 is functionally expressed in human endothelial cells, and its activity is negatively regulated by inflammatory cytokines. Our findings might provide a new insight into understanding the treatment of cardiovascular diseases with AA.
Influence of the Type of Membrane and Heparin on Serum Lipid Parameters during a Dialysis Session: A Pilot Study
Authors: Katopodis Konstantinos P. , Elisaf Moses , Balafa Olga , Nikolopoulos Petros , Bairaktari Eleni , Katsaraki Afroditi , Siamopoulos Kostas C.
Published: September 2004

Background/Aim: The type of heparin and membrane used might influence the lipids in patients on hemodialysis (HD). However, there are limited and debatable data concerning the lipid changes during an HD session. The aim of our study was to examine the changes in serum lipid parameters during the HD session in relation to the heparin and dialysis membrane used. Methods: Ten patients on HD 3 times/week participated in the study. The study was performed in three phases (A, B, C), each of 1 week’s duration. The types of membranes used were Hemophan (phase A), ethylene vinyl alcohol (phase B) and polyacrylonitrile (phase C), respectively, in a random order. During the midweek session of each phase we used classic heparin, while during the session at the end of the week low molecular weight heparin was administered. Serum total cholesterol, triglycerides, HDL cholesterol, Lp(a), albumin and total proteins were measured before and 5 min after the HD and hourly during the HD session. Results: In all phases, we found a progressive increase in all lipid parameters during the HD session, except Lp(a). This increase, however, was possibly due to hemoconcentration. Conclusions: This pilot study showed that (1) the type of heparin and membrane used does not seem to affect the serum lipid profile during a single HD procedure, and (2) the changes observed in serum lipid parameters are mainly due to hemoconcentration.
Nonparametric analysis of replicated microarray experiments
Authors: Gannoun Ali , Saracco Jérôme , Urfer Wolfgang , Bonney George E.
Published: September 2004

Microarrays are part of a new class of biotechnologies, which allow the monitoring of expression levels of thousands of genes simultaneously. In microarray data analysis, the comparison of gene expression profiles with respect to different conditions and the selection of biologically interesting genes are crucial tasks. Multivariate statistical methods have been applied to analyze these large data sets. To identify genes with altered expression under two experimental conditions, we propose a nonparametric statistical approach. Specifically, we propose estimating the distributions of a t-type statistic and its null statistic, using kernel methods. A comparison of these two distributions by means of a likelihood ratio test can identify genes with significantly changed expressions. A new method to provide more stable estimates of tail probabilities is proposed, as well as a method for the calculation of the cut-off point and the acceptance region. The methodology is applied to a leukaemia data set containing expression levels of 7129 genes, and is compared with normal mixture model and the traditional t-test.
Marginal models for zero inflated clustered data
Authors: Hall Daniel B , Zhang Zhengang
Published: September 2004

Over the last decade or so, there has been increasing interest in ‘zero inflated’ (ZI) regression models to account for ‘excess’ zeros in data. Examples include ZI poisson (ZIP), ZI binomial (ZIB), ZI negative binomial and ZI tobit models. Recently, extensions of these models to the clustered data case have begun to appear. For example, Hall considered ZIP and ZIB models with cluster specific random effects. In this paper, we consider an alternative expectation maximization approach on the basis of marginal models and generalized estimating equation (GEE) methodology. In the usual EM algorithm for fitting ZI models, the M step is replaced by the solution of a GEE to take into account within cluster correlation. The details of this approach, including formulas for an asymptotic variance-covariance matrix of parameter estimates, are given for several of the most important ZI regression model classes. Alternatively, GEEs can be applied directly by computing the first two marginal moments of the observed response. We illustrate these two marginal modeling approaches with examples, and compare them via a small simulation study.
Why does surface ozone peak in summertime at Waliguan?
Authors: Zhu Bin , Akimoto Hajime , Wang Zifa , Sudo Kengo , Tang Jie , Uno Itsushi
Published: September 2004

The seasonal variation of boundary layer ozone over East Asia is investigated using a regional scale chemical transport model, with the initial and boundary conditions of chemical species obtained from a global chemistry model. Comparisons with observations indicate that the model reproduces the main daily and seasonal features of ozone over eastern Asia. The seasonal variation of ozone has a summer maximum and winter minimum at Waliguan station (on the northeastern edge of the Tibetan Plateau), rather than the spring maximum and summer minimum seen at many other observational sites in the East Asian Pacific rim region. Model results suggest that there is band of a high ozone between 35°N∼45°N from the western boundary (70°E) to 130°E in the summertime. It is concluded that the seasonal transitions associated with the Asian monsoon system and transport from eastern/central China, Central/South Asia and even Europe are significantly responsible for the distinct ozone seasonal cycle at Waliguan.
Experimental rock‐on‐rock frictional wear: Application to subglacial abrasion
Authors: Lee A. G. G. , Rutter E. H.
Published: September 2004

Rock‐on‐rock wear under known normal loads was measured experimentally using 62 mm diameter rotating discs machined from a range of silicic rock types: one granite, two metamorphic rocks, and three sandstones of porosities varying between 7% and 28%. Wear debris was removed continuously from the contacting surfaces by water. We obtained a wear law of the form dT/dx = Aσnϕm, where σ is contact normal stress (MPa), dT/dx is a dimensionless wear rate (meter wear (T) per meter shear displacement (x)), ϕ is porosity, and A, n, and m are empirical constants, 10−8.11, 8.33, and 4.50, respectively. Low‐porosity rocks displayed surface polishing, and abraded particle size was substantially smaller than the starting grain size. Whole grains were plucked from high‐porosity rocks, without any surface polishing, so that the wear product particle size remained the same as that of the starting material. The empirical wear law describes abrasion beneath a hard‐bedded temperate glacier, provided we can estimate both the in situ normal stress between entrained clasts and the bed and the horizontal velocity of the clasts in the flowing ice. Normal stress concentration is expected to develop at clast/bed contacts from drag against ice flowing toward the bed, where pressure melting occurs. These experimental data are consistent with wear rates inferred from silt outflow in subglacial streams, provided a tenfold stress concentration can occur relative to the ice overburden pressure. The rate of production of fine‐grained wear products under subglacial conditions is substantially less than by tectonic faulting.
Repertaxin, a novel inhibitor of rat CXCR2 function, inhibits inflammatory responses that follow intestinal ischaemia and reperfusion injury
Authors: Souza Danielle G , Bertini Riccardo , Vieira Angelica T , Cunha Fernando Q , Poole Steve , Allegretti Marcello , Colotta Francesco , Teixeira Mauro M
Published: September 2004

Neutrophils are thought to play a major role in the mediation of reperfusion injury. CXC chemokines are known inducers of neutrophil recruitment. Here, we assessed the effects of Repertaxin, a novel low molecular weight inhibitor of human CXCL8 receptor activation, on the local, remote and systemic injuries following intestinal ischaemia and reperfusion (I/R) in the rat.

Pre‐incubation of rat neutrophils with Repertaxin (10−11–10−6M) inhibited the chemotaxis of neutrophils induced by human CXCL8 or rat CINC‐1, but not that induced by fMLP, PAF or LTB4, in a concentration‐dependent manner. Repertaxin also prevented CXCL8‐induced calcium influx but not CXCL8 binding to purified rat neutrophils.

In a model of mild I/R injury (30 min of ischaemia and 30 min of reperfusion), Repertaxin dose‐dependently (3–30 mg kg−1) inhibited the increase in vascular permeability and neutrophil influx. Maximal inhibition occurred at 30 mg kg−1.

Following severe I/R injury (120 min of ischaemia and 120 min of reperfusion), Repertaxin (30 mg kg−1) markedly prevented neutrophil influx, the increase in vascular permeability both in the intestine and the lungs. Moreover, there was prevention of haemorrhage in the intestine of reperfused animals.

Repertaxin effectively suppressed the increase in tissue (intestine and lungs) and serum concentrations of TNF‐α and the reperfusion‐associated lethality.

For comparison, we also evaluated the effects of an anti‐CINC‐1 antibody in the model of severe I/R injury. Overall, the antibody effectively prevented tissue injury, systemic inflammation and lethality. However, the effects of the antibody were in general of lower magnitude than those of Repertaxin.

In conclusion, CINC‐1 and possibly other CXC chemokines, acting on CXCR2, have an important role during I/R injury. Thus, drugs, such as Repertaxin, developed to block the function of the CXCR2 receptor may be effective at preventing reperfusion injury in relevant clinical situations.

British Journal of Pharmacology (2004) 143, 132–142. doi:10.1038/sj.bjp.0705862