bluuebunny/crossref_metadata_2025 huggingface dataset:
Physical Partitioning is the Main Mechanism of α‐Tocopherol and Cholesterol Transfer between Lipoproteins and P388D1Macrophage‐Like Cells
Authors: Asmis Reto
Published: September 2004

The regulation of cellular vitamin E concentration was studied in P388D1macrophage‐like cells. Cellular α‐tocopherol levels increased more than 5000‐fold over constitutive levels without reaching saturation when P388D1cells were cultured in vitamin‐E‐supplemented fetal calf serum. The uptake of α‐tocopherol was accompanied by accumulation of α‐[3H]tocopherol and [14C]cholesterol in these cells. Human unmodified low‐density lipoprotein (LDL) inhibited the uptake of α‐[3H]tocopherol and [14C]cholesterol in a dose‐dependent manner and with very similar IC50. Acetylated, Cu2+‐oxidized and aggregated human LDL and human very‐low‐density‐lipoprotein (VLDL) were similarly potent, whereas human HDL was at least tenfold less effective than human LDL when inhibitory activity was correlated to lipoprotein protein levels. The rate of vitamin E uptake by P388D1cells, however, always correlated with the extracellular α‐tocopherol/cholesterol ratio. Efflux of α‐[3H]tocopherol from labeled P388D1cells required extracellular acceptors and was accompanied by the concomitant release of [14C]cholesterol. Both human LDL and HDL could serve as acceptors. Changes in the cellular α‐tocopherol level appear to be the direct consequence of changes in the extracellular α‐tocopherol/cholesterol ratio due to a rapid exchange of lipids between P388D1cells and their extracellular environment. While the transfer of α‐tocopherol from LDL, VLDL, and fetal calf serum into P388D1cells appears to occur mainly by diffusion, HDL‐stimulated efflux of α‐tocopherol may underlie a different mechanism. The α‐tocopherol/cholesterol ratio of the extracellular environment may be a critical factor in determining cellular vitamin E levelsin vivo.
Microbial diversity of extant stromatolites in the hypersaline marine environment of Shark Bay, Australia
Authors: Burns Brendan P. , Goh Falicia , Allen Michelle , Neilan Brett A.
Published: September 2004

Stromatolites have been present on Earth, at various levels of distribution and diversity, for more than 3 billion years. Today, the best examples of stromatolites forming in hypersaline marine environments are in Hamelin Pool at Shark Bay, Western Australia. Despite their evolutionary significance, little is known about their associated microbial communities. Using a polyphasic approach of culture‐dependent and culture‐independent methods, we report the discovery of a wide range of microorganisms associated with these biosedimentary structures. There are no comparable reports combining these methodologies in the survey of cyanobacteria, bacteria, and archaea in marine stromatolites. The community was characterized by organisms of the cyanobacterial genera Synechococcus, Xenococcus, Microcoleus, Leptolyngbya, Plectonema, Symploca, Cyanothece, Pleurocapsa and Nostoc. We also report the discovery of potentially free‐living Prochloron. The other eubacterial isolates and clones clustered into seven phylogenetic groups: OP9, OP10, Marine A group, Proteobacteria, Low G+C Gram‐positive, Planctomycetes and Acidobacteria. We also demonstrate the presence of sequences corresponding to members of halophilic archaea of the divisions Euryarchaeota and Crenarchaeota and methanogenic archaea of the order Methanosarcinales. This is the first report of such archaeal diversity from this environment. This study provides a better understanding of the microbial community associated with these living rocks.
A New ‘Biased Coin Design’ for the Sequential Allocation of Two Treatments
Authors: Antognini Alessandro Baldi , Giovagnoli Alessandra
Published: September 2004

Efron’s biased coin design is a well-known randomization technique that helps to neutralize selection bias in sequential clinical trials for comparing treatments, while keeping the experiment fairly balanced. Extensions of the biased coin design have been proposed by several researchers who have focused mainly on the large sample properties of their designs. We modify Efron’s procedure by introducing an adjustable biased coin design, which is more flexible than his. We compare it with other existing coin designs; in terms of balance and lack of predictability, its performance for small samples appears in many cases to be an improvement with respect to the other sequential randomized allocation procedures.
Regression-Based Estimation of the False Negative Fraction When Multiple Negatives are Unverified
Authors: Lloyd Chris J. , Frommer Donald J.
Published: September 2004

The paper describes a method of estimating the false negative fraction of a multiple-screening test when individuals who test negatively on all K tests do not have their true disease status verified. The method proposed makes no explicit assumptions about the underlying heterogeneity of the population or about serial correlation of test results within an individual. Rather, it is based on estimating false negative fractions conditionally on observed diagnostic histories and extrapolating the observed patterns in these empirical frequencies by using logistic regression. The method is illustrated on, and motivated by, data on a multiple-screening test for bowel cancer.
Risk‐Neutral Parameter Shifts and Derivatives Pricing in Discrete Time
Authors: SCHRODER MARK
Published: September 2004

We obtain a large class of discrete‐time risk‐neutral valuation relationships, or “preference‐free” derivatives pricing models, by imposing a simple restriction on the state‐price density process. The risk‐neutral stock‐return and forward‐rate dynamics are obtained by changing only a location parameter, which can be determined independent of the preference and true location parameters. The Gaussian models of Rubinstein (1976), Brennan (1979), and Câmera (2003), and the gamma model of Heston (1993) are all special cases. The model provides simple relationships between expected returns and state‐price density parameters analogous to the diffusion case.
Competition and Coalition among Underwriters: The Decision to Join a Syndicate
Authors: SONG WEI‐LING
Published: September 2004

This paper studies the decision of lead investment banks to organize hybrid syndicates (commercial banks participating as co‐managers) versus pure investment bank syndicates. The findings show that hybrid underwriting issues are more challenging to float. Compared to pure investment bank syndicates, hybrid syndicates serve clients that are smaller, have lower common stock rankings and less prior access to the capital markets, rely more on bank loans, and invest less capital but issue larger amounts, which indicates that commercial banks' participation enhances hybrid services. Moreover, lead investment banks tend to invite banks' participation when clients exhibit higher loyalty in reusing their services.
A Survey of IRB Process in 68 U.S. Hospitals
Authors: Larson Elaine , Bratts Tiffany , Zwanziger Jack , Stone Patricia
Published: September 2004

Purpose

: To compare IRB processes in 68 U.S. hospitals for the same multicenter study.

Design

: Survey of IRB processes in 68 U.S. hospitals during 2001‐2002.

Methods

: Requirements of IRB submission including type and duration of review and qualifications of principal investigator were compared by hospital bed size, region, and academic affiliation.

Findings

: The majority of hospitals (63.2%) were on the East coast, and mean bed size was 465 (range: 77‐2,112). About one‐third (33.8%) required that the principal investigator listed on the application be from within the institution, 26.5% required evidence of human subjects research training, 10.3% required a conflict of interest statement. Mean number of pages for the application was 5.24 (1‐31) and up to eight copies were requested. Time from submission of the IRB application to approval averaged 45.4 days (range, 1‐303 days), and the majority of reviews were “expedited” (61.8%). Expedited reviews required more time (mean, 54.8 days) than did either exempt (mean, 10.8 days) or full (mean, 47.1 days) reviews.

Conclusions

: Current IRB review processes are cumbersome and nonstandardized, and review time varies widely. The absence of efficient and streamlined review might unnecessarily impede national clinical research projects without improving participant safety.
Testing Predator-Driven Evolution with Paleozoic Crinoid Arm Regeneration
Authors: Baumiller Tomasz K. , Gahn Forest J.
Published: September 2004

Regenerating arms of crinoids represent direct evidence of nonlethal attacks by predators and provide an opportunity for exploring the importance of predation through geologic time. Analysis of 11 Paleozoic crinoid Lagerstätten revealed a significant increase in arm regeneration during the Siluro-Devonian. During this interval, referred to as the Middle Paleozoic Marine Revolution, the diversity of shell-crushing predators increased, and antipredatory morphologies among invertebrate prey, such as crinoids, became more common. Crinoid armregeneration data suggest an increase in nonlethal attacks at this time and represent a causal link between those patterns, which implies an important role for predator-driven evolution.
Requirement of a Relatively High Threshold Level of Mg
2+
for Cell Growth of a Rhizoplane Bacterium,
Sphingomonas yanoikuyae
EC-S001
Authors: Hoo Henny , Hashidoko Yasuyuki , Islam Md. Tofazzal , Tahara Satoshi
Published: September 2004

Mg
2+
is one of the essential elements for bacterial cell growth. The presence of the magnesium cation (Mg
2+
) in various concentrations often affects cell growth restoration in plant-associating bacteria. This study attempted to determine whether Mg
2+
levels in
Sphingomonas yanoikuyae
EC-S001 affected cell growth restoration in the host plant and what the threshold level is.
S. yanoikuyae
EC-S001, isolated from the rhizoplane of spinach seedlings grown from surface-sterilized seeds under aseptic conditions, displayed uniform dispersion and attachment throughout the rhizoplane and phylloplane of the host seedlings.
S. yanoikuyae
EC-S001 did not grow in potato-dextrose broth medium but grew well in an aqueous extract of spinach leaves. Chemical investigation of the growth factor in the spinach leaf extract led to identification of the active principle as the magnesium cation. A concentration of ca. 0.10 mM Mg
2+
or more allowed
S. yanoikuyae
EC-S001 to grow in potato-dextrose broth medium. Some saprophytic and/or diazotrophic bacteria used in our experiment were found to have diverse threshold levels for their Mg
2+
requirements. For example,
Burkholderia cepacia
EC-K014, originally isolated from the rhizoplane of a
Melastoma
sp., could grow even in Mg
2+
-free Hoagland's no. 2 medium with saccharose and glutamine (HSG medium) and requires a trace level of Mg
2+
for its growth. In contrast,
S. yanoikuyae
EC-S001, together with
Bacillus subtilis
IFO12113, showed the most drastic restoring responses to subsequent addition of 0.98 mM Mg
2+
to Mg
2+
-free HSG medium. Our studies concluded that Mg
2+
is more than just the essential trace element needed for cell growth restoration in
S. yanoikuyae
EC-S001 and that certain nonculturable bacteria may require a higher concentration of Mg
2+
or another specific essential element for their growth.
Comparative Proteomic Analysis of Extracellular Proteins of Enterohemorrhagic and Enteropathogenic
Escherichia coli
Strains and Their
ihf
and
ler
Mutants
Authors: Li M. , Rosenshine I. , Tung S. L. , Wang X. H. , Friedberg D. , Hew C. L. , Leung K. Y.
Published: September 2004

Enterohemorrhagic and enteropathogenic
Escherichia coli
(EHEC and EPEC, respectively) strains are closely related human pathogens that are responsible for food-borne epidemics in many countries. Integration host factor (IHF) and the locus of enterocyte effacement-encoded regulator (Ler) are needed for the expression of virulence genes in EHEC and EPEC, including the elicitation of actin rearrangements for attaching and effacing lesions. We applied a proteomic approach, using two-dimensional polyacrylamide gel electrophoresis in combination with matrix-assisted laser desorption ionization-time of flight mass spectrometry and a protein database search, to analyze the extracellular protein profiles of EHEC EDL933, EPEC E2348/69, and their
ihf
and
ler
mutants. Fifty-nine major protein spots from the extracellular proteomes were identified, including six proteins of unknown function. Twenty-six of them were conserved between EHEC EDL933 and EPEC E2348/69, while some of them were strain-specific proteins. Four common extracellular proteins (EspA, EspB, EspD, and Tir) were regulated by both IHF and Ler in EHEC EDL933 and EPEC E2348/69. TagA in EHEC EDL933 and EspC and EspF in EPEC E2348/69 were present in the wild-type strains but absent from their respective
ler
and
ihf
mutants, while FliC was overexpressed in the
ihf
mutant of EPEC E2348/69. Two dominant forms of EspB were found in EHEC EDL933 and EPEC E2348/69, but the significance of this is unknown. These results show that proteomics is a powerful platform technology for accelerating the understanding of EPEC and EHEC pathogenesis and identifying markers for laboratory diagnoses of these pathogens.
Multiple Nonidentical Reductive-Dehalogenase-Homologous Genes Are Common in
Dehalococcoides
Authors: Hölscher Tina , Krajmalnik-Brown Rosa , Ritalahti Kirsti M. , von Wintzingerode Friedrich , Görisch Helmut , Löffler Frank E. , Adrian Lorenz
Published: September 2004

Degenerate primers were used to amplify large fragments of reductive-dehalogenase-homologous (RDH) genes from genomic DNA of two
Dehalococcoides
populations, the chlorobenzene- and dioxin-dechlorinating strain CBDB1 and the trichloroethene-dechlorinating strain FL2. The amplicons (1,350 to 1,495 bp) corresponded to nearly complete open reading frames of known reductive dehalogenase genes and short fragments (approximately 90 bp) of genes encoding putative membrane-anchoring proteins. Cloning and restriction analysis revealed the presence of at least 14 different RDH genes in each strain. All amplified RDH genes showed sequence similarity with known reductive dehalogenase genes over the whole length of the sequence and shared all characteristics described for reductive dehalogenases. Deduced amino acid sequences of seven RDH genes from strain CBDB1 were 98.5 to 100% identical to seven different RDH genes from strain FL2, suggesting that both strains have an overlapping substrate range. All RDH genes identified in strains CBDB1 and FL2 were related to the RDH genes present in the genomes of
Dehalococcoides ethenogenes
strain 195 and
Dehalococcoides
sp. strain BAV1; however, sequence identity did not exceed 94.4 and 93.1%, respectively. The presence of RDH genes in strains CBDB1, FL2, and BAV1 that have no orthologs in strain 195 suggests that these strains possess dechlorination activities not present in strain 195. Comparative sequence analysis identified consensus sequences for cobalamin binding in deduced amino acid sequences of seven RDH genes. In conclusion, this study demonstrates that the presence of multiple nonidentical RDH genes is characteristic of
Dehalococcoides
strains.
Modified Serial Analysis of Gene Expression Method for Construction of Gene Expression Profiles of Microbial Eukaryotic Species
Authors: Coyne Kathryn J. , Burkholder JoAnn M. , Feldman Robert A. , Hutchins David A. , Cary S. Craig
Published: September 2004

Serial analysis of gene expression (SAGE) is a powerful approach for the identification of differentially expressed genes, providing comprehensive and quantitative gene expression profiles in the form of short tag sequences. Each tag represents a unique transcript, and the relative frequencies of tags in the SAGE library are equal to the relative proportions of the transcripts they represent. One of the major obstacles in the preparation of SAGE libraries from microorganisms is the requirement for large amounts of starting material (i.e., mRNA). Here, we present a novel approach for the construction of SAGE libraries from small quantities of total RNA by using Y linkers to selectively amplify 3′ cDNA fragments. To validate this method, we constructed comprehensive gene expression profiles of the toxic dinoflagellate
Pfiesteria shumwayae
. SAGE libraries were constructed from an actively toxic fish-fed culture of
P. shumwayae
and from a recently toxic alga-fed culture.
P. shumwayae-
specific gene transcripts were identified by comparison of tag sequences in the two libraries. Representative tags with frequencies ranging from 0.026 to 3.3% of the total number of tags in the libraries were chosen for further analysis. Expression of each transcript was confirmed in separate control cultures of toxic
P. shumwayae
. The modified SAGE method described here produces gene expression profiles that appear to be both comprehensive and quantitative, and it is directly applicable to the study of gene expression in other environmentally relevant microbial species.
Localization and Characterization of Two Novel Genes Encoding Stereospecific Dioxygenases Catalyzing 2(2,4-Dichlorophenoxy)propionate Cleavage in
Delftia acidovorans
MC1
Authors: Schleinitz Kathleen M. , Kleinsteuber Sabine , Vallaeys Tatiana , Babel Wolfgang
Published: September 2004

Two novel genes,
rdpA
and
sdpA
, encoding the enantiospecific α-ketoglutarate dependent dioxygenases catalyzing
R
,
S
-dichlorprop cleavage in
Delftia acidovorans
MC1 were identified. Significant similarities to other known genes were not detected, but their deduced amino acid sequences were similar to those of other α-ketoglutarate dioxygenases. RdpA showed 35% identity with TauD of
Pseudomonas aeruginosa
, and SdpA showed 37% identity with TfdA of
Ralstonia eutropha
JMP134. The functionally important amino acid sequence motif HX(D/E)X
23-26
(T/S)X
114-183
HX
10-13
R/K, which is highly conserved in group II α-ketoglutarate-dependent dioxygenases, was present in both dichlorprop-cleaving enzymes. Transposon mutagenesis of
rdpA
inactivated
R
-dichlorprop cleavage, indicating that it was a single-copy gene. Both
rdpA
and
sdpA
were located on the plasmid pMC1 that also carries the lower pathway genes. Sequencing of a 25.8-kb fragment showed that the dioxygenase genes were separated by a 13.6-kb region mainly comprising a Tn
501
-like transposon. Furthermore, two copies of a sequence similar to IS
91
-like elements were identified. Hybridization studies comparing the wild-type plasmid and that of the mutant unable to cleave dichlorprop showed that
rdpA
and
sdpA
were deleted, whereas the lower pathway genes were unaffected, and that deletion may be caused by genetic rearrangements of the IS
91
-like elements. Two other dichlorprop-degrading bacterial strains,
Rhodoferax
sp. strain P230 and
Sphingobium herbicidovorans
MH, were shown to carry
rdpA
genes of high similarity to
rdpA
from strain MC1, but
sdpA
was not detected. This suggested that
rdpA
gene products are involved in the degradation of
R
-dichlorprop in these strains.
Clearance of Human-Pathogenic Viruses from Sludge: Study of Four Stabilization Processes by Real-Time Reverse Transcription-PCR and Cell Culture
Authors: Monpoeho S. , Maul A. , Bonnin C. , Patria L. , Ranarijaona S. , Billaudel S. , Ferré V.
Published: September 2004

Sludges derived from wastewater treatment are foul-smelling, biologically unstable substances. As well as containing numerous pathogenic microorganisms, they also consist of organic matter that can be used as agricultural fertilizer. Legislation nevertheless requires sludges to be virologically tested prior to spreading by the counting of infectious enterovirus particles. This method, based on culture of enterovirus on BGM cells, is lengthy and not very sensitive. The aim of this study was to propose an alternative method of genome quantification for all enteroviruses that is applicable to verifying the elimination of viruses in complex samples such as sludges. Our complete protocol was compared to the official method, consisting of enterovirus enumeration with the most probable number of cythopathic unit (MPNCU) assay through the study of four stabilization procedures: liming, composting, heat treatment, and mesophile anaerobic digestion. Enterovirus quantities at the start of the stabilization procedures were between 37 and 288 MPNCU/g on the one scale and between 4 and 5 log genome copies/g on the other. It was shown that all procedures except mesophile anaerobic digestion were highly effective in the elimination of enterovirus particles and genomes in wastewater sludges. Reduction of viruses by mesophile anaerobic digestion was by only 1 log (infectious particles and genomes). In conclusion, stabilization processes can indeed be checked by virological quality control of sludges with gene amplification. However, the infectivity of genomes needs to be confirmed with cell culture or a correlation model if the virological risk inherent in the agricultural use of such sludges is to be fully addressed.
Competition between Ammonia-Oxidizing Bacteria and Benthic Microalgae
Authors: Risgaard-Petersen Nils , Nicolaisen Mette H. , Revsbech Niels Peter , Lomstein Bente Aa
Published: September 2004

The abundance, activity, and diversity of ammonia-oxidizing bacteria (AOB) were studied in prepared microcosms with and without microphytobenthic activity. In the microcosm without alga activity, both AOB abundance, estimated by real-time PCR, and potential nitrification increased during the course of the experiment. AOB present in the oxic zone of these sediments were able to fully exploit their nitrification potential because NH4+did not limit growth. In contrast, AOB in the alga-colonized sediments reached less than 20% of their potential activity, suggesting starvation of cells. Starvation resulted in a decrease with time in the abundance of AOB as well as in nitrification potential. This decrease was correlated with an increase in alga biomass, suggesting competitive exclusion of AOB by microalgae. Induction of N limitation in the oxic zone of the alga-colonized sediments and O2limitation of the majority of AOB in darkness were major mechanisms by which microalgae suppressed the growth and survival of AOB. The competition pressure from the algae seemed to act on the entire population of AOB, as no differences were observed by denaturing gradient gel electrophoresis ofamoAfragments during the course of the experiment. Enumeration of bacteria based on 16S rRNA gene copies andd-amino acids suggested that the algae also affected other bacterial groups negatively. Our data indicate that direct competitive interaction takes place between algae and AOB and that benthic algae are superior competitors because they have higher N uptake rates and grow faster than AOB.
Lactococcal Plasmid pNP40 Encodes a Novel, Temperature-Sensitive Restriction-Modification System
Authors: O'Driscoll Jonathan , Glynn Frances , Cahalane Oonagh , O'Connell-Motherway Mary , Fitzgerald Gerald F. , van Sinderen Douwe
Published: September 2004

A novel restriction-modification system, designated LlaJI, was identified on pNP40, a naturally occurring 65-kb plasmid from
Lactococcus lactis
. The system comprises four adjacent similarly oriented genes that are predicted to encode two m
5
C methylases and two restriction endonucleases. The LlaJI system, when cloned into a low-copy-number vector, was shown to confer resistance against representatives of the three most common lactococcal phage species. This phage resistance phenotype was found to be strongly temperature dependent, being most effective at 19°C. A functional analysis confirmed that the predicted methylase-encoding genes,
llaJIM1
and
llaJIM2
, were both required to mediate complete methylation, while the assumed restriction enzymes, specified by
llaJIR1
and
llaJIR2
, were both necessary for the complete restriction phenotype. A Northern blot analysis revealed that the four LlaJI genes are part of a 6-kb operon and that the relative abundance of the LlaJI-specific mRNA in the cells does not appear to contribute to the observed temperature-sensitive profile. This was substantiated by use of a LlaJI promoter-
lacZ
fusion, which further revealed that the LlaJI operon appears to be subject to transcriptional regulation by an as yet unidentified element(s) encoded by pNP40.
Isolation and Characterization of a Rolling-Circle-Type Plasmid from
Rhodococcus erythropolis
and Application of the Plasmid to Multiple-Recombinant-Protein Expression
Authors: Nakashima Nobutaka , Tamura Tomohiro
Published: September 2004

We isolated, sequenced, and characterized the cryptic plasmid pRE8424 from
Rhodococcus erythropolis
DSM8424. Plasmid pRE8424 is a 5,987-bp circular plasmid; it carries six open reading frames and also contains
cis
-acting elements, specifically a single-stranded origin and a double-stranded origin, which are characteristic of rolling-circle-replication plasmids. Experiments with pRE8424 derivatives carrying a mutated single-stranded origin sequence showed that single-stranded DNA intermediates accumulated in the cells because of inefficient conversion from single-stranded DNA to double-stranded DNA. This result indicates that pRE8424 belongs to the pIJ101/pJV1 family of rolling-circle-replication plasmids. Expression vectors that are functional in several
Rhodococcus
species were constructed by use of the replication origin from pRE8424. We previously reported a cryptic plasmid, pRE2895, from
R. erythropolis
, which may replicate by a θ-type mechanism, like ColE2 plasmids. The new expression vectors originating from pRE8424 were compatible with those derived from pRE2895. Coexpression experiments with these compatible expression vectors indicated that the plasmids are suitable for the simultaneous expression of multiple recombinant proteins.
Implicating the Glutathione-Gated Potassium Efflux System as a Cause of Electrophile-Induced Activated Sludge Deflocculation
Authors: Bott Charles B. , Love Nancy G.
Published: September 2004

The glutathione-gated K+efflux (GGKE) system represents a protective microbial stress response that is activated by electrophilic or thiol-reactive stressors. It was hypothesized that efflux of cytoplasmic K+occurs in activated sludge communities in response to shock loads of industrially relevant electrophilic chemicals and results in significant deflocculation.Novosphingobium capsulatum, a bacterium consistent with others found in activated sludge treatment systems, responded to electrophilic thiol reactants with rapid efflux of up to 80% of its cytoplasmic K+pool. Furthermore,N. capsulatumand activated sludge cultures exhibited dynamic efflux-uptake-efflux responses very similar to those observed by others inEscherichia coliK-12 exposed to the electrophilic stressorsN-ethylmaleimide and 1-chloro-2,4-dinitrobenzene and the reducing agent dithiothreitol. Fluorescent LIVE/DEAD stains were used to show that cell lysis was not the cause of electrophile-induced K+efflux. Nigericin was used to artificially stimulate K+efflux fromN. capsulatumand activated sludge cultures as a comparison to electrophile-induced K+efflux and showed that cytoplasmic K+efflux by both means corresponded with activated sludge deflocculation. These results parallel those of previous studies with pure cultures in which GGKE was shown to cause cytoplasmic K+efflux and implicate the GGKE system as a probable causal mechanism for electrophile-induced, activated sludge deflocculation. Calculations support the notion that shock loads of electrophilic chemicals result in very high K+concentrations within the activated sludge floc structure, and these K+levels are comparable to that which caused deflocculation by external (nonphysiological) KCl addition.
Potential Role for Fish in Transmission of
Mycobacterium ulcerans
Disease (Buruli Ulcer): an Environmental Study
Authors: Eddyani Miriam , Ofori-Adjei David , Teugels Guy , De Weirdt David , Boakye Daniel , Meyers Wayne M. , Portaels Françoise
Published: September 2004

This study reports a potential role that fish may play in the transmission of
Mycobacterium ulcerans
disease (Buruli ulcer). Fish found positive for
M. ulcerans
DNA all appear to feed on insects or plankton and are believed to concentrate
M. ulcerans
from this usual food source. These observations provide additional data supporting our previous hypothesis on sources of
M. ulcerans
and modes of transmission.
Stimulus Dependence of Disparity Coding in Primate Visual Area V4
Authors: Hegdé Jay , Van Essen David C.
Published: September 2004

Disparity tuning in visual cortex has been shown using a variety of stimulus types that contain stereoscopic depth cues. It is not known whether different stimuli yield similar disparity tuning curves. We studied whether cells in visual area V4 of the macaque show similar disparity tuning profiles when the same set of disparity values were tested using bars or dynamic random dot stereograms, which are among the most commonly used stimuli for this purpose. In a majority of V4 cells (61%), the shape of the disparity tuning profile differed significantly for the two stimulus types. The two sets of stimuli yielded statistically indistinguishable disparity tuning profiles for only a small minority (6%) of V4 cells. These results indicate that disparity tuning in V4 is stimulus-dependent. Given the fact that bar stimuli contain two-dimensional (2-D) shape cues, and the random dot stereograms do not, our results also indicate that V4 cells represent 2-D shape and binocular disparity in an interdependent fashion, revealing an unexpected complexity in the analysis of depth and three-dimensional shape.
Cortical Injury Affects Short-Term Plasticity of Evoked Excitatory Synaptic Currents
Authors: Li Huifang , Bandrowski Anita E. , Prince David A.
Published: September 2004

The hypothesis that plastic changes in the efficacy of excitatory neurotransmission occur in areas of chronic cortical injury was tested by assessing short-term plasticity of evoked excitatory synaptic currents (EPSCs) in neurons of partially isolated neocortical islands (undercut cortex). Whole cell recordings were obtained from layer V pyramidal neurons of sensorimotor cortical slices prepared from P36–P43 control and undercut rats. AMPA/kainate receptor-mediated EPSCs elicited by stimuli delivered at 40 to 66.7 Hz exhibited more paired-pulse depression (PPD) in undercut cortex than control, the time constant of depression evoked by trains of 20- to 66.7-Hz stimuli was faster, and the steady-state amplitude of EPSCs reached after five to seven EPSCs was lower. An antagonist of the glutamate autoreceptor, group II mGluR, increased the steady-state amplitude of EPSCs from undercut but not control cortex, suggesting that activation of presynaptic receptors by released glutamate is more prominent in undercut cortex. In contrast, the GABAB receptor antagonist (2S)-3-[[(1S)-1-(3,4-dichlorophenyl)ethyl]amino-2-hydroxypropyl](phenylmethyl)phosphinic acid had no effect. Increasing [Ca2+]o from 2 to 4 mM increased PPD, with a smaller effect in neurons of the undercut. The I-V relationship of AMPA/kainate receptor-mediated EPSCs was close to linear in both control and undercut neurons, and spermine had no significant effect on the EPSCs, suggesting that decreases in postsynaptic glutamate receptors containing the GluR2 subunit were not involved in the alterations in short-term plasticity. Results are compatible with an increase in the probability of transmitter release at excitatory synapses in undercut cortex due to functional changes in presynaptic terminals.
Modulation of Grasping Forces During Object Transport
Authors: Smith Michael A. , Soechting John F.
Published: September 2004

Subjects held an instrumented object in a tripod grasp and moved it in the horizontal plane in various directions. The contact forces at the digits were measured and the grip force was decomposed into 2 components: a manipulating force responsible for accelerating the object and a grasping force responsible for holding the object steady. The grasping forces increased during the movement, reaching a peak near the time of peak velocity. The grasping forces also exhibited directional tuning, but this tuning was idiosyncratic for each subject. Although the overall grip forces should be modulated with acceleration, the load force did not vary during the task. Therefore the increase in the grasping force is not required to prevent slip. Rather, it is suggested that grasping force increases during translational motion to stabilize the orientation of grasped objects.
Modulation of Gaze-Evoked Blinks Depends Primarily on Extraretinal Factors
Authors: Williamson Shawn S. , Zivotofsky Ari Z. , Basso Michele A.
Published: September 2004

Gaze-evoked blinks are contractions of the orbicularis oculi (OO)—the lid closing muscle—occurring during rapid movements of the head and eyes and result from a common drive to the gaze and blink motor systems. However, blinks occurring during shifts of gaze are often suppressed when the gaze shift is made to an important visual stimulus, suggesting that the visual system can modulate the occurrence of these blinks. In head-stabilized, human subjects, we tested the hypothesis that the presence of a visual stimulus was sufficient, but not necessary, to modulate OO EMG (OOemg) activity during saccadic eye movements. Rapid, reorienting movements of the eyes (saccades) were made to visual targets that remained illuminated (visually guided trials) or were briefly flashed (memory-guided trials) at different amplitudes along the horizontal meridian. We measured OOemg activity and found that the magnitude and probability of OOemg activity occurrence was reduced when a saccade was made to the memory of the spatial location as well as to the actual visual stimulus. The reduced OOemg activity occurred only when the location of the target was previously cued. OOemg activity occurred reliably with spontaneous saccades that were made to locations with no explicit visual stimulus, generally, back to the fixation location. Thus the modulation of gaze-evoked OOemg activity does not depend on the presence of visual information per se, but rather, results from an extraretinal signal.
Wisdom as Expert Knowledge System: A Critical Review of a Contemporary Operationalization of an Ancient Concept
Authors: Ardelt Monika
Published: September 2004

Paul B. Baltes and his colleagues, who are among the most prominent contemporary wisdom researchers, define wisdom as ‘expert knowledge in the domain fundamental pragmatics of life.’ By contrast, this article argues that the definition, operationalization, and measurement of wisdom should not be reduced to expertise and that the term wisdom should be reserved for wise persons rather than expert knowledge. In fact, evidence from their research confirms that Baltes et al. primarily assess expert or intellectual knowledge in the wisdom domain ‘fundamental pragmatics of life’ rather than how wise people are. As an alternative, a model of wisdom is presented that defines, operationalizes, and measures wisdom as an integration of cognitive, reflective, and affective personality characteristics.
A Genomic- and Proteomic-Based Hypothesis on the Eclectic Effects of Systemic Interleukin-2 Administration in the Context of Melanoma-Specific Immunization
Authors: Panelli Monica C. , Martin Brian , Nagorsen Dirk , Wang Ena , Smith Kina , Monsurro Vladia , Marincola Francesco M.
Published: September 2004

Among human cancers, melanoma is characterized by an almost unique predisposition to regress in response to immune therapy. Recent clinical studies suggest that the frequency of this favorable event is enhanced by combining T-cell-directed active specific immunization with the systemic administration of interleukin (IL)-2. While waiting for additional clinical experience to confirm this observation, we embraced the working hypothesis that this combination provides superior response rates than either treatment alone. In particular, we have focused our interest on the paradoxical observation that active specific immunization consistently induces circulating CD8+ T cells capable of recognizing in ex vivo assays tumor cells, but cannot induce tumor regression alone. In these settings, it appears that combining the systemic administration of IL-2 is almost an absolute requirement for the induction of clinical responses. Here, we will expand on previous speculations on the postulated mechanism(s) of action of systemic IL-2 administration and, based on original data recently derived through high-throughput transcriptional and post-translational analysis, we will suggest an explanation for the eclectic effects of IL-2 administration in the context of active specific immunization.
Progress in the Use of Adeno-Associated Viral Vectors for Gene Therapy
Authors: Büning Hildegard , Braun-Falco Markus , Hallek Michael
Published: September 2004

The development of safe and efficient gene transfer vectors is crucial for the success of gene therapy trials. A viral vector system promising to meet these requirements is based on the apathogenic adeno-associated virus (AAV-2), a member of the parvovirus family. The advantages of this vector system is the stability of the viral capsid, the low immunogenicity, the ability to transduce both dividing and non-dividing cells, the potential to integrate site specifically and to achieve long-term gene expression even in vivo, and its broad tropism allowing the efficient transduction of diverse organs including the skin. All this makes AAV-2 attractive and efficient for in vitro gene transfer and local injection in vivo. This review covers the progress made in AAV vector technology including the development of AAV vectors based on other serotypes, summarizes the results obtained by AAV targeting vectors and outlines potential applications in the field of cutaneous gene therapy.
Genetic Immunization with Multiple HIV-1 Genes Provides Protection against HIV-1/MuLV Pseudovirus Challenge in vivo
Authors: Hinkula Jorma , Rollman Erik , Lundholm Peter , Benthin Reinhold , Okuda Kenji , Wahren Britta
Published: September 2004

Superinfection by HIV-1 of a cell line containing the complete murine leukemia virus (MuLV) genome was shown to give rise to pseudotyped HIV-1/MuLV. Such superinfection was successful with certain strains of HIV-1 subtypes A–D. Primary spleen cells and cells of the peritoneal cavity of immunocompetent mice of the C57Bl/6 strain were infectable with the pseudotype HIV-1/MuLV and secreted HIV-1 in vitro and in vivo. In contrast, the murine cell lines, NIH 3T3, myeloma cell line Sp2/0, and two murine hybridoma cell lines were relatively resistant to infection and produced no or little HIV. After primary murine spleen cells had been infected with pseudotyped HIV-1 and transferred to C57Bl/6 mice, replication-competent HIV-1 was obtained from the peritoneal cavity for at least 10–14 days. High amounts (>105 vRNA copies/ml) of HIV-1 vRNA could be measured in the peritoneal fluid. Presence of HIV-1 proviral DNA was detectable in cells from the peritoneal cavity for up to 24 days after infected cell transfer. Active reverse transcriptase representing both HIV-1 and C-type murine retroviruses was detected in the peritoneal washes. The HIV-infected spleen cells injected into the peritoneal cavity elicited HIV-1-specific cellular immune responses to p24gag, gp160Env, Nef, Tat and Rev. Mice immunized with HIV-1 DNA, but not with HIV-1 protein, cleared their HIV-1-infected cells within 10–14 days after challenge with HIV-1/MuLV-infected syngeneic spleen cells. This novel model system of primarily cellular reactivity to HIV-1-infected cells in vivo may become useful for assaying experimental HIV-1 immunization schedules.
Effects of Long-Term Intervention with Lactobacillus helveticus-Fermented Milk on Bone Mineral Density and Bone Mineral Content in Growing Rats
Authors: Narva Mirkka , Collin Marika , Lamberg-Allardt Christel , Kärkkäinen Merja , Poussa Tuija , Vapaatalo Heikki , Korpela Riitta
Published: September 2004

Background:Lactobacillus helveticus-fermented milk has been shown to increase calcium absorption compared to ordinary sour milk. In the present study the possible effect of L. helveticus-fermented milk on bone was studied in growing rats. Methods: Spontaneously hypertensive male rats, which develop an osteoporotic bone disorder with age, were randomized into 5 groups (n = 10) receiving milk fermented with L. helveticus 16H and, as reference drinks, milk fermented with L. helveticus and Saccharomyces cerevisiae, sour milk, skim milk or water, for 14 weeks. After the intervention bone mineral density and bone mineral content were measured by dual-energy X-ray absorptiometry. The femur weight, length and volume were measured before ashing. From the ashes the weight and mineral content were assessed. Results: As the body weight gain differed significantly between the groups, the results were related to the body weight. The L. helveticus-fermented milk intervention significantly increased the bone mineral density and bone mineral content compared to the sour milk, skim milk and water interventions. The mean values of the bone mineral density and bone mineral content were higher in the L. helveticus-fermented milk group compared to the Saccharomyces-fermented milk group but the difference was not statistically significant. Conclusion:L. helveticus-fermented milk increases bone mineral density and bone mineral content in relation to body weight in the long-term feeding of growing rats. The mechanism of L. helveticus remains to be discovered.
What Have the New Definition of Acute Myocardial Infarction and the Introduction of Troponin Measurement Done to the Coronary Care Unit?
Authors: Amit Guy , Gilutz Harel , Cafri Carlos , Wolak Arik , Ilia Reuben , Zahger Doron
Published: September 2004

Objective: To assess the impact of the new American College of Cardiology/European Society of Cardiology definition of acute myocardial infarction (AMI) and the introduction of troponin measurement on the coronary care unit (CCU). Methods: This was a retrospective cohort study performed in a tertiary care university hospital. All admissions to the CCU during the year before (period 1, year 2000, n = 1,134) and the year after (period 2, year 2002, n = 1,360) the introduction of troponin measurement and the new AMI definition were studied. We studied baseline characteristics, case load, distribution of admission diagnoses, management and outcome of patients in the two periods. Results: There was a 20% increase in the number of CCU admissions, driven solely by a 141% increase in the burden of non-ST elevation AMI (NSTEMI) (p < 0.01). This increase was not a mere reflection of a change in diagnostic criteria, as the overall burden of non-ST elevation acute coronary syndromes (ACS) (NSTEMI + unstable angina) increased by 46%, suggesting referral of many more patients to the CCU. Despite a 42% increase in the number of angiograms performed, the proportion of ACS patients who had an angiogram declined. AMI patients in period 2 were older and had higher rates of coronary risk factors but had a higher chance of receiving a guideline-based therapy. Length of CCU stay decreased by a whole day for all ACS patients. 30-day mortality for AMI patients did not change significantly. Conclusions: The new AMI definition had a dramatic impact on the CCU case load, case mix and length of stay and on the ability to provide early coronary angiography.
Chromosomal Constitution of Embryos Derived from Tripronuclear Zygotes Studied by Fluorescence in situ Hybridization Using Probes for Chromosomes 4, 13, 18, 21, X, and Y
Authors: Pang Myung-Geol , Jee Byung-Chul , Kim Seok-Hyun , Ryu Buom-Yong , Oh Sun-Kyung , Suh Chang-Suk , Moon Shin-Yong
Published: September 2004

This study was designed to assess the chromosomal constitution and segregation patterns of cleaving embryos derived from tripronuclear zygotes. Thirty-two embryos obtained from 19 conventional IVF patients were analyzed by fluorescence in situ hybridization (FISH) using probes for chromosomes 4, 13, 18, 21, X, and Y. Sixteen embryos (50.0%) exhibited uniform, non-mosaic patterns. These embryos showed pure triploid (n = 7), pure diploid (n = 7), or pure haploid (n = 2). The remaining 16 embryos showed mosaic patterns; 1 was triploid-diploid mosaics, 9 were diploid-haploid, and 4 were haploid only. Autosomal aneuploidy occurred in 2 embryos showing a triploid complement. The sex chromosomal constituent XXX:XXY:XYY was 3:4:2 in embryos showing a pure triploid complement (including 2 embryos with aneuploidy). This ratio was not significantly different from the expected 1:2:1 (p = 0.96). Pure triploid was found in 41.7% of 2-cell embryos, but no triploid complement was found in 3-cell embryos. The present study also supports the diandric origin of tripronuclear zygotes in the conventional IVF, and, to our knowledge, is the first study to use simultaneous six-color FISH for chromosomes 4, 13, 18, 21, X, and Y in human embryos. However, no additive information was obtained about chromosome 4.
Doppler and Immunohistochemical Evaluation of Decidual Spiral Arteries in Early Pregnancy
Authors: Carbillon Lionel , Ziol Marianne , Challier Jean-Claude , Perrot Nicolas , Uzan Michèle , Prevot Sophie , Uzan Serge
Published: September 2004

Objective: The purpose of this study was to estimate spiral artery subchorionic flow at 8–11 gestational weeks (GW) by Doppler ultrasound and then to analyze these vessels in the decidua basalis using histologic, morphometric and immunohistochemical analyses. Methods: Subchorionic spiral arteries were evaluated in 5 women scheduled for aspiration at 8–11 GW. Flow velocity waveforms were sought using color and pulsed Doppler, and the diastolic/systolic (D/S) index was calculated. Transcervical biopsy specimens and aspiration products were thoroughly examined to investigate the structure of the spiral artery at the implantation site using cytotrophoblastic and arterial smooth muscle cell immunohistochemical markers (anti-cytokeratin 7 and anti-actin monoclonal antibodies). Spiral artery cross-sectional inner areas were measured and compared with the D/S index in each case. Results: Low-impedance pulsatile flow could be detected below the trophoblastic ring in all cases. Complete obstruction of a spiral artery lumen was never observed and cytotrophoblastic cells were incorporated into the vessel wall starting from the perivascular cuff. Conclusion: Both techniques evidenced that decidual spiral arteries in the placental bed are not completely obstructed at 8–11 GW.
Influence of Mechanical, Cellular, and Molecular Factors on Collateral Artery Growth (Arteriogenesis)
Authors: Heil Matthias , Schaper Wolfgang
Published: September 2004

Growth of collateral blood vessels (arteriogenesis) is potentially able to preserve structure and function of limbs and organs after occlusion of a major artery. The success of the remodeling process depends on the following conditions: (1) existence of an arteriolar network that connects the preocclusive with the postocclusive microcirculation; (2) activation of the arteriolar endothelium by elevated fluid shear stress; (3) invasion (but not incorporation) of bone marrow–derived cells; and (4) proliferation of endothelial and smooth muscle cells. Most organs of most mammals including man can rely on the existence of interconnecting arterioles in most organs and tissues with heart being the exception in rodents and pigs. Arterial occlusion lowers the pressure in the distal vasculature thereby creating a pressure gradient favoring increased flow through preexisting collaterals. This increases fluid shear stress leading to endothelial activation with cellular edema, upregulation of adhesion molecules, mitogenic-, thrombogenic-, and fibrinolytic factors, leading to monocyte invasion with matrix digestion. Smooth muscle cells migrate and proliferate and the vessel enlarges under the influence of increasing circumferential wall stress. Growth factors involved belong to the FGF family and signaling proceeds via the Ras/Raf- and the Rho cascades. Increases in vascular radius and wall thickness restore fluid shear stress and circumferential wall stress to normal levels and growth stops. Although increases in collateral vessel size are very substantial their maximal conductance amounts to only 40% of normal. Forced increases in FSS can reach almost 100%.