bluuebunny/crossref_metadata_2025 huggingface dataset:
Isolation and characterization of 43 microsatellite DNA markers for guppy (Poecilia reticulata)
Authors: Watanabe T. , Yoshida M. , Nakajima M. , Taniguchi N.
Published: November 2003

Thirty‐nine polymorphic microsatellite DNA markers were isolated from the guppy (Poecilia reticulata) genomic library. All of the loci showed moderate allelic variation ranging from two to seven alleles, with observed heterozygosities from 0.000 to 0.938. The microsatellite DNA markers isolated will be available for use in analysis of quantitative trait loci in breeding programmes and for population genetic studies on experimental fish.
Isolation and characterization of highly polymorphic microsatellite markers from the marine invasive species Crepidula fornicata (Gastropoda: Calyptraeidae)
Authors: Dupont L. , Viard F.
Published: November 2003

Many marine organisms have pelagic larvae and these are often important agents of dispersal and establishment of exotic species. The larval phase and the hermaphroditic reproductive system of the invasive marine gastropod Crepidula fornicata are crucial in determining the success of this species along the European coasts. To analyse these factors, we developed seven microsatellite loci specific to C. fornicata. On the same set of individuals, the microsatellite loci exhibited a greater level of polymorphism than previously studied allozyme markers and, thus, will permit fine‐scale analysis and larval pool studies.
Thirty‐four polymorphic microsatellites for European roe deer
Authors: Vial L. , Maudet C. , Luikart G.
Published: November 2003

The European roe deer (Capreolus capreolus) is an interesting model for molecular ecology studies because of its abundance and adaptability across a range of environments (including human‐modified habitats), and because of its increasing impacts on agricultural crops and on regenerating forests. We identify polymorphic microsatellites in two managed populations of roe deer in France by using cross‐species amplification of primers from other Cervids and from Bovids. Of the 62 primer pairs tested, 45 amplified microsatellites in roe deer, and 34 were polymorphic. Eleven primer pairs were selected for multiplex gel‐loading for routine genotyping of the studied populations.
Microsatellite loci isolated from narrow‐leaved cattail Typha angustifolia
Authors: Tsyusko‐Omeltchenko Olga V. , Schable Nancy A. , Smith Michael H. , Glenn Travis C.
Published: November 2003

We present 11 dinucleotide microsatellite DNA loci isolated from the narrow‐leaved cattail (Typha angustifolia) and describe conditions for their amplification. The PCR primers were tested on at least 20 individuals of Typha angustifolia and T. latifolia from two Ukrainian populations per species. The primers amplify loci with relatively high numbers of alleles (averaging 7.22 and 4.95 alleles per locus in T. angustifolia and T. latifolia, respectively), and polymorphic information content (averaging 0.61 and 0.46 in T. angustifolia and T. latifolia, respectively).
Development and characterization of polymorphic microsatellite markers from Fragaria viridis, a wild diploid strawberry
Authors: Sargent D. J. , Hadonou A. M. , Simpson D. W.
Published: November 2003

To date, the development of microsatellite (SSR) markers in the genus Fragaria has focused on F. vesca. However, further species are thought to have contributed to the complex allo‐octoploid genome of the cultivated strawberry, F.×ananassa. Here, we present 22 new SSR markers developed from the diploid species F. viridis. Twenty‐one of the primer pairs amplified polymorphisms in six F. viridis accessions, with an average of 4.95 alleles per primer pair and an average expected heterozygosity of 0.68. Fourteen of these primer pairs, and a locus monomorphic in F. viridis, amplified polymorphic alleles in the parents of a F. vesca mapping population.
Novel polymorphic microsatellite markers for the common pandora (Pagellus erythrinus)
Authors: RamŠak Andreja , Garoia Flavio , Guarniero Ilaria , Mannini Piero , Tinti Fausto
Published: November 2003

Details of six highly polymorphic dinucleotide and one highly polymorphic tetranucleotide microsatellite markers are provided for Pagellus erythrinus. These markers are highly polymorphic, with an expected heterozygosity ranging from 0.713 to 0.959 and allele numbers ranging from seven to 36. These microsatellite markers should help determine population genetic structure and fisheries stocks for management purposes.
Development of microsatellite DNA loci from the wood stork (Aves, Ciconiidae, Mycteria americana)
Authors: Tomasulo‐Seccomandi Alessandra M. , Schable Nancy A. , Lawrence Bryan A. , Lehr Brisbin I. , Del Lama Silvia N. , Glenn Travis C.
Published: November 2003

We isolated 11 polymorphic microsatellite loci for wood stork (Mycteria americana). Polymerase chain reaction (PCR) primers and conditions are described for the amplification of five dinucleotide, one trinucleotide and five tetranucleotide microsatellite loci. The PCR primers were tested on two wood stork populations, Fazenda Ipiranga, Mato Grosso, Brazil (n = 11) and Tamiami West, Everglades, Florida, USA (n = 20). The primers yielded two to four alleles per locus, an observed heterozygosity of 0.0–0.727 and a polymorphic information content of 0.048–0.604. The low level of polymorphism for these markers is consistent with previous studies of this species.
PCR primers for microsatellite loci in the desert tortoise (Gopherus agassizii, Testudinidae)
Authors: Edwards Taylor , Goldberg Caren S. , Kaplan Matthew E. , Schwalbe Cecil R. , Swann Don E.
Published: November 2003

The desert tortoise, Gopherus agassizii, is a threatened species native to the North American desert southwest and is recognized as having distinct Mojave and Sonoran populations. We identified six polymorphic microsatellite loci in the desert tortoise. All six loci were polymorphic in Sonoran samples. Five of the loci were variable in Mojave samples with varying degrees of amplification success. Two of the loci exhibited low allelic variation (2–3 alleles) while four were highly variable (8–27 alleles).
Microsatellite isolation and characterization in the beneficial parasitoid wasp Diaeretiella rapae (M’Intosh) (Hymenoptera: Braconidae: Aphidiinae)
Authors: Macdonald C. , Brookes C. P. , Edwards K. J. , Baker D. A. , Lockton S. , Loxdale H. D.
Published: November 2003

The primary parasitoid wasp, Diaeretiella rapae (M’Intosh), is used as a biological control agent in insect pest management strategies to combat aphid pests, mainly on cruciferous plants. To investigate the spatial scales over which this beneficial parasitoid wasp moves within an agricultural landscape, we developed five polymorphic microsatellite markers. The number of alleles per locus ranged from 11 to 21. Cross‐species amplification indicated that these loci may be useful in some other members of the Aphidiinae.
Isolation and characterization of microsatellite loci in the flour mite Acarus siro
Authors: Learmount J. , Conyers C. M. , Chaudhry M. Q. , Macnicoll A. D.
Published: November 2003

Thirteen microsatellites with dinucleotide repeats were isolated from genomic DNA in solution by hybridization capture. Eleven were evaluated against Acarus siro using a multiple‐tube approach to assess polymorphism and reliability of the results. The multiple‐tube method demonstrated the presence of null alleles due to low levels of DNA. Seven of the 11 microsatellite loci were polymorphic and six produced reliable amplification products, if results only from individuals that scored at all six loci were used in the analysis. These were evaluated in eight strains of A. siro. Two of the samples showed some genetic divergence using FST values.
Characterization of twenty‐four microsatellite markers for rainbow trout (Oncorhynchus mykiss)
Authors: Rodriguez F. , Rexroad C. E. , Palti Y.
Published: November 2003

Twenty‐four new microsatellite markers were developed for genome mapping and population genetics studies in rainbow trout (Oncorhynchus mykiss). The amount of polymorphism, percentage heterozygosity and ability of each marker to amplify genomic DNA from other salmonids were recorded. Seven markers were observed to be duplicated in the rainbow trout genome by containing more than one allele in homozygous (clonal) fish.
bottlesim: a bottleneck simulation program for long‐lived species with overlapping generations
Authors: Kuo C.‐H. , Janzen F. J.
Published: November 2003

Population bottlenecks reduce genetic diversity and thus cause great concern in conservation biology. Previous theoretical studies often assume discrete generations in projecting declines in genetic diversity caused by bottlenecks. This assumption creates complexities when applying the models to long‐lived species with overlapping generations. bottlesim is a program for simulating bottlenecks to estimate the impact on genetic diversity; the novelties include an overlapping‐generation model, a wide range of reproductive systems, and flexible population size settings. With these features, bottlesim will be a useful tool for estimating the genetic consequences of bottlenecks, evaluating conservation plans, and performing power analysis.
Black as Me: Narrative Identity
Authors: Baylis Françoise
Published: November 2003

This commentary responds to genetic testing of African ancestry through a series of personal narratives that reveal a complex, intimate, and individualised process of identity formation. The author discusses both how her family and others outside her family have fostered and challenged her sense of black identity. She concludes by maintaining that racial identity is not in the genes but in the world in which we live and the stories we construct and are able to maintain.
Genomics of Helicobacter 2003
Authors: Björkholm Britta , Salama Nina R.
Published: November 2003

Research on Helicobacter pylori has been driven by the field of genomics since the release of the first of two complete genome sequences in 1997. In this review we highlight progress made in the last year. New bioinformatics tools and methods promise better functional and strain comparative analyses of individual genes. Sequence‐based methods of strain comparison documented the coevolution of H. pylori with human populations. Several comprehensive analyses of the bacterial transcriptome were undertaken as well as two sophisticated studies of the transcriptional response of specific host tissues in response to H. pylori infection using different mouse models of H. pylori diseases. Some progress was made in developing genetic tools for mutational analysis of the genes required for infection. Finally, proteomic approaches were refined to delineate surface exposed and secreted proteins that represent potential antigens. In summary, while we do not have the full story of H. pylori, significant progress in deciphering the genome into functional biology has been made.
Helicobacter pylori– inflammation, immunity and vaccines
Authors: Michetti Pierre , Svennerholm Ann‐Mari
Published: November 2003

The mechanisms by which Helicobacter pylori escape the host immune response remains an important topic. Regulatory T cells appear to play a role in the persistence of the infection and the control of tissue damage. In the thought that the host genetic background influences the cross‐talk between pathogens and hosts, the impact of cytokine polymorphisms on the outcome of H. pylori has been further delineated in the review period. On the other hand, several additional genes of H. pylori have been shown to participate in the pro‐inflammatory cytokine and chemokine response to the infection. Finally, progress has been achieved in vaccine development, with new vaccine delivery systems and routes of immunization tested in animal models and human volunteers.
Helicobacter pylori infection in pediatrics
Authors: Wewer Vibeke , Kalach Nicolas
Published: November 2003

A high prevalence and early colonization of Helicobacter pylori infection in childhood was described again this year in developing countries in contrast to developed ones. Upper gastrointestinal endoscopy including gastric biopsies remains the diagnostic gold standard method for this infection. Also noninvasive tests have been studied in children, including serology, 13C‐urea breath test and stool antigen test, showing good results in the different age groups as compared to the gold standard. However, the infection often remains asymptomatic in children and the role of this bacterium in gastric manifestations is the subject of conflicting reports. Extra‐digestive manifestations are also reported in the course of this infection. The treatment of H. pylori infection is influenced by resistance of the bacteria to the antibiotics used. We suggest that eradication of H. pylori should take place only after susceptibility testing. The association of a proton pump inhibitor and two antibiotics for 1 or 2 weeks gives the best eradication rates. The crucial question to elucidate is whether asymptomatic children should be treated to prevent cancer in the future.
Helicobacter pylori and extragastric diseases – Other Helicobacters
Authors: Gasbarrini Antonio , Carloni Emilia , Gasbarrini Giovanni , Ménard Armelle
Published: November 2003

The role of Helicobacter pylori infection is explored in more and more extragastric diseases without definite proof in most of the studies, except possibly some hematologic diseases. In cardiovascular diseases, including stroke, the presence of CagA positive strains may be involved. The possible role of helicobacters in hepatobiliary diseases goes beyond that of H. pylori to involve enterohepatic helicobacters. New Helicobacter species are regularly described and molecular methods are developed to improve their detection. Helicobacter felis remains the major species to be used in animal models of Helicobacter infection.
Development of an Optrode for Intramural Multisite Optical Recordings of Vm in the Heart
Authors: BYARS JONATHAN L. , SMITH WILLIAM M. , IDEKER RAYMOND E. , FAST VLADIMIR G.
Published: November 2003

Introduction: Optical mapping of transmembrane potential (Vm) is an important tool in the investigation of impulse propagation in the heart. It provides valuable information about spatiotemporal changes of Vm that cannot be obtained by other techniques, but it presently is limited to measurements from the heart surfaces. Therefore, the goal of this work was to develop a technique for intramural multisite optical measurements of Vm using fiberoptic technology.

Methods and Results: An optrode, a bundle of thin optical fibers, was developed for measuring intramural optical signals at multiple sites in the heart. The optrode consisted of seven fibers with diameter of 225 μm arranged in a hexagonal pattern that were used to deliver excitation light to the myocardium, to collect the emitted fluorescence, and to project the light onto a 16 × 16 array of photodiode detectors. Rabbit hearts were stained with the Vm‐sensitive dye RH‐237. Fluorescence was excited using a 100‐W Hg lamp. Intramural action potentials were recorded at multiple sites separated by 2 mm inside the left ventricle. Signal‐to‐noise (RMS) ratio was 21.2 ± 12 (n = 7) without averaging or ratiometry and with negligible cross‐talk (<1.9%) between the neighboring photodiodes. The size of the recording area for an individual fiber was estimated at approximately 0.8 mm.

Conclusion: These data demonstrate feasibility of multisite transmural measurements of Vm without signal averaging and ratiometry. This technique might become useful in studies of transmural impulse conduction during arrhythmias and defibrillation. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1196‐1202, November 2003)
Arterial desaturation during exercise in man: implication for O2 uptake and work capacity
Authors: Nielsen Henning Bay
Published: November 2003

Exercise‐induced arterial hypoxaemia is defined as a reduction in the arterial O2 pressure (PaO2) by more than 1 kPa and/or a haemoglobin O2 saturation (SaO2) below 95%. With blood gas analyses ideally reported at the actual body temperature, desaturation is a consistent finding during maximal ergometer rowing. Arterial desaturation is most pronounced at the end of a maximal exercise bout, whereas the reduction in PaO2 is established from the onset of exercise. Exercise‐induced arterial hypoxaemia is multifactorial. The ability to maintain a high alveolar O2 pressure (PAO2) is critical for blood oxygenation and this appears to be difficult in large individuals. A large lung capacity and, in turn, diffusion capacity seem to protect PaO2. A widening of the PAO2–PaO2 difference does indicate that a diffusion limitation, a ventilation–perfusion mismatch and/or a shunt influence the transport of O2 from alveoli to the pulmonary capillaries. An inspired O2 fraction of 0.30 reduces the widened PAO2–PaO2 difference by 75% and prevents a reduction of PaO2 and SaO2. With a marked increase in cardiac output, diffusion limitation combined with a fast transit time dominates the O2 transport problem. Furthermore, a postexercise reduction in pulmonary diffusion capacity suggests that the alveolo‐capillary membrane is affected. An antioxidant attenuates oxidative burst by neutrophilic granulocytes, but it does not affect PaO2, SaO2 or O2 uptake (VO2), and the ventilatory response to maximal exercise also remains the same. It is proposed, though, that increased concentration of certain cytokines correlates to exercise‐induced hypoxaemia as cytokines stimulate mast cells and basophilic granulocytes to degranulate histamine. The basophil count increases during maximal rowing. Equally, histamine release is associated with hypoxaemia and when the release of histamine is prevented, the reduction in PaO2 is attenuated.

During maximal exercise, an extreme lactate spill‐over to blood allows pH decrease to below 7.1 and according to the O2 dissociation curve this is critical for SaO2. When infusion of sodium bicarbonate maintains a stable blood buffer capacity, acidosis is attenuated and SaO2 increases from 89% to 95%. This enables exercise capacity to increase, an effect also seen when O2 supplementation to inspired air restores arterial oxygenation. In that case, exercise capacity increases less than can be explained by VO2 and CaO2. Furthermore, the change in muscle oxygenation during maximal exercise is not affected when hyperoxia and sodium bicarbonate attenuate desaturation. It is proposed that other organs benefit from enhanced O2 availability, and especially the brain appears to increase its oxygenation during maximal exercise with hyperoxia.
Adaptive Product, Process and Tooling Design Strategy for Optimal Dimensional Quality of Automotive Body Assemblies
Authors: Zhang Bai , Ni Jun
Published: November 2003

Research investigations have shown that the dimensional quality is deeply rooted in the whole process of the product development, from product, process and tooling design, the tooling manufacturing process, to the production. Unlike rigid body assembly, automotive body assembly has its unique characteristics. The final dimensions of automotive bodies depend not only on the variations/deviations and rigidity of components, tooling/process variation, but also on the product structure, connection type and assembly sequence. An adaptive strategy for automotive body development is here by presented to exploit these unique features. By the adaptive product, process and tooling design strategy, the dimensional variation/deviation for the key dimensions can be significantly reduced and the die tryout time be shorten with significant cost saving.
Red‐cell lifetimes calculated from 51Cr red‐cell survival data
Authors: Widman J. C. , Powsner E. R.
Published: November 2003

The activity of red cells labeled with 51Cr decreases exponentially due to elution of chromium from the cell and any random cell losses which may be present, and decreases linearly due to red‐cell senescence. Red‐cell survival data are fitted to the function , where is the activity at time , is the initial activity, is the exponential loss rate, and is the cell lifetime. With many subjects, , and as well as the standard errors of the estimate of these parameters may be determined.
A neutron collimator for animal irradiations
Authors: Goldberg E. , Barschall H. H. , Booth R. , Griffith R. V. , Phillips T. L.
Published: November 2003

A collimator for exposures of portions of small animals to 15‐MeV neutrons is described. The radiation field behind the collimator was mapped with various detectors that determined dose, neutron spectra, and fluxes.
Identification and Characterization of the Nickel Uptake System for Urease Biogenesis in
Streptococcus salivarius
57.I
Authors: Chen Yi-Ywan M. , Burne Robert A.
Published: November 2003

Ureases are multisubunit enzymes requiring Ni
2+
for activity. The low pH-inducible urease gene cluster in
Streptococcus salivarius
57.I is organized as an operon, beginning with
ureI
, followed by
ureABC
(structural genes), and
ureEFGD
(accessory genes). Urease biogenesis also requires a high-affinity Ni
2+
uptake system. By searching the partial genome sequence of a closely related organism,
Streptococcus thermophilus
LMG18311, three open reading frame (ORFs) homologous to those encoding proteins involved in cobalamin biosynthesis and cobalt transport (
cbiMQO
) were identified immediately 3′ to the
ure
operon. To determine whether these genes were involved in urease biogenesis by catalyzing Ni
2+
uptake in
S. salivarius
, regions 3′ to
ureD
were amplified by PCRs from
S. salivarius
by using primers identical to the
S. thermophilus
sequences. Sequence analysis of the products revealed three ORFs. Reverse transcriptase PCR was used to demonstrate that the ORFs are transcribed as part of the
ure
operon. Insertional inactivation of ORF1 with a polar kanamycin marker completely abolished urease activity and the ability to accumulate
63
Ni
2+
during growth. Supplementation of the growth medium with NiCl
2
at concentrations as low as 2.5 μM partially restored urease activity in the mutant. Both wild-type and mutant strains showed enhanced urease activity when exogenous Ni
2+
was provided at neutral pH. Enhancement of urease activity by adding nickel was regulated at the posttranslational level. Thus, ORF1, ORF2, and ORF3 are part of the
ure
operon, and these genes, designated
ureM
,
ureQ
, and
ureO
, respectively, likely encode a Ni
2+
-specific ATP-binding cassette transporter.
Factors Contributing to Hydrogen Peroxide Resistance in
Streptococcus pneumoniae
Include Pyruvate Oxidase (SpxB) and Avoidance of the Toxic Effects of the Fenton Reaction
Authors: Pericone Christopher D. , Park Sunny , Imlay James A. , Weiser Jeffrey N.
Published: November 2003

Aerobic growth of
Streptococcus pneumoniae
results in production of amounts of hydrogen peroxide (H
2
O
2
) that may exceed 1 mM in the surrounding media. H
2
O
2
production by
S. pneumoniae
has been shown to kill or inhibit the growth of other respiratory tract flora, as well as to have cytotoxic effects on host cells and tissue. The mechanisms allowing
S. pneumoniae
, a catalase-deficient species, to survive endogenously generated concentrations of H
2
O
2
that are sufficient to kill other bacterial species is unknown. In the present study, pyruvate oxidase (SpxB), the enzyme responsible for endogenous H
2
O
2
production, was required for survival during exposure to high levels (20 mM) of exogenously added H
2
O
2
. Pretreatment with H
2
O
2
did not increase H
2
O
2
resistance in the mutant, suggesting that SpxB activity itself is required, rather than an H
2
O
2
-inducible pathway.
SpxB
mutants synthesized 85% less acetyl-phosphate, a potential source of ATP. During H
2
O
2
exposure, ATP levels decreased more rapidly in
spxB
mutants than in wild-type cells, suggesting that the increased killing of
spxB
mutants was due to more rapid ATP depletion. Together, these data support the hypothesis that
S. pneumoniae
SpxB contributes to an H
2
O
2
-resistant energy source that maintains viability during oxidative stress. Thus, SpxB is required for resistance to the toxic by-product of its own activity. Although H
2
O
2
-dependent hydroxyl radical production and the intracellular concentration of free iron were similar to that of
Escherichia coli
, killing by H
2
O
2
was unaffected by iron chelators, suggesting that
S. pneumoniae
has a novel mechanism to avoid the toxic effects of the Fenton reaction.
Analysis of theCorynebacterium diphtheriaeDtxR Regulon: Identification of a Putative Siderophore Synthesis and Transport System That Is Similar to theYersiniaHigh-Pathogenicity Island-Encoded Yersiniabactin Synthesis and Uptake System
Authors: Kunkle Carey A. , Schmitt Michael P.
Published: November 2003

The diphtheria toxin repressor, DtxR, is a global iron-dependent regulatory protein inCorynebacterium diphtheriaethat controls gene expression by binding to 19-bp operator sequences. To further define the DtxR regulon inC. diphtheriae, a DtxR repressor titration assay (DRTA) was developed and used to identify 10 previously unknown DtxR binding sites. Open reading frames downstream from seven of the newly identified DtxR binding sites are predicted to encode proteins associated with iron or heme transport. Electrophoretic mobility shift assays indicated that DtxR was able to bind to DNA fragments carrying the 19-bp operator regions, and transcriptional analysis of putative promoter elements adjacent to the binding site sequences revealed that most of these regions displayed iron- and DtxR-regulated activity. A putative siderophore biosynthesis and transport operon located downstream from one of the DtxR binding sites, designatedsid, is similar to the yersiniabactin synthesis and uptake genes encoded on theYersinia pestishigh pathogenicity island. The siderophore biosynthetic genes in thesidoperon contained a large deletion in theC. diphtheriaeC7 strain, but thesidgenes were unaffected in four clinical isolates that are representative of the dominant strains from the recent diphtheria epidemic in the former Soviet Union. Mutations in the siderophore biosynthetic genes in a clinical strain had no effect on siderophore synthesis or growth in low-iron conditions; however, a mutation in one of the putative transport proteins,cdtP, resulted in reduced growth in iron-depleted media, which suggests that this system may have a role in iron uptake. The findings from this study indicate thatC. diphtheriaecontains at least 18 DtxR binding sites and that DtxR may affect the expression of as many as 40 genes.
Subtractive Hybridization Reveals a Type I Polyketide Synthase Locus Specific to
Mycobacterium ulcerans
Authors: Jenkin Grant A. , Stinear Timothy P. , Johnson Paul D. R. , Davies John K.
Published: November 2003

Mycobacterium ulcerans
causes Buruli ulcer, the third most prevalent mycobacterial infection of immunocompetent humans after tuberculosis and leprosy. Recent work has shown that the production by
M. ulcerans
of mycolactone, a novel polyketide, may partly explain the pathogenesis of Buruli ulcer. To search for the genetic basis of virulence in
M. ulcerans
, we took advantage of the close genetic relationship between
M. ulcerans
and
Mycobacterium marinum
by performing genomic suppressive subtractive hybridization of
M. ulcerans
with
M. marinum
. We identified several DNA fragments specific to
M. ulcerans
, in particular, a type I polyketide synthase locus with a highly repetitive modular arrangement. We postulate that this locus is responsible for the synthesis of mycolactone in
M. ulcerans
.
Quinolone Resistance Due to Reduced Target Enzyme Expression
Authors: Ince Dilek , Hooper David C.
Published: November 2003

We report for the first time low-level quinolone resistance mediated by decreased expression of topoisomerase IV in
Staphylococcus aureus
. A single-step mutant of wild-type
S. aureus
strain ISP794, P18 selected by using twice the MIC of premafloxacin, had four- and four- to eightfold greater MICs of premafloxacin and ciprofloxacin, respectively, than the wild type. Sequencing of
parEC
and
gyrBA
with their promoter regions revealed a point mutation (G→A) 13 bp upstream of the start codon of
parE
. Genetic linkage studies showed that there was a high level of correlation between the mutation and the resistance phenotype, and allelic exchange confirmed the contribution of the mutation to resistance. Decreased expression of ParE and decreased steady-state levels of
parEC
transcripts in P18 and in resistant allelic exchange mutants were observed. The steady-state levels of
gyrBA
and
topB
transcripts were increased in P18 but not in two resistant allelic exchange mutants, and sequencing upstream of either gene did not reveal a difference between ISP794 and P18. The steady-state levels of
topA
transcripts were similar in the various strains. Growth competition experiments performed at 30, 37, and 41°C with a susceptible allelic exchange strain and a resistant allelic exchange strain suggested that loss of fitness was associated with reduced levels of ParE at 41°C. However, P18 had a growth advantage over ISP794 at all temperatures, suggesting that a compensatory mechanism was associated with the increased levels of
gyrBA
and
topB
transcripts. Thus, reduced levels of ParE appear to be compatible with cell survival, although there may be a fitness cost during rapid cell multiplication, which might be overcome by compensatory mechanisms without reversion of the resistance phenotype.
Role of the Stationary Growth Phase Sigma Factor RpoS of
Burkholderia pseudomallei
in Response to Physiological Stress Conditions
Authors: Subsin Benchamas , Thomas Mark S. , Katzenmeier Gerd , Shaw Jonathan G. , Tungpradabkul Sumalee , Kunakorn Mongkol
Published: November 2003

The
Burkholderia pseudomallei rpoS
gene was identified, and an
rpoS
null mutant was constructed. The mutant was shown to have an increased sensitivity to carbon starvation and oxidative stress. By using
rpoS-lacZ
fusions, transcription of
rpoS
was shown to be growth phase regulated, reaching a peak upon entry into stationary phase.
Sedimentary Cladoceran remains and their relationship to nutrients and other limnological variables in 53 lakes from British Columbia, Canada
Authors: Bos Darren G , Cumming Brian F
Published: November 2003

To develop models to predict past lake-water nutrient levels, the sedimentary remains of Cladocera were sampled from 53 lakes in central British Columbia, Canada. At the same time, the lakes were sampled for a suite of chemical variables. In addition, a host of physical and spatial explanatory variables were collected from each site. Canonical correspondence analysis showed that total phosphorus (TP), which ranged from 5 to 146 µg·L1, was the measured environmental variable that best described the differences in species composition among the lakes. Additionally, lake depth and surface water temperature were also important in explaining the distribution of cladoceran taxa. Chydorus brevilabris, Daphnia ambigua, Daphnia cf. pulex, and Graptoleberis testudinaria had a preference for eutrophic lakes, whereas Acroperus harpae, Alonella nana, Alonella excisa, Chydorus piger, Daphnia cf. dentifera, and Eubosmina spp. were found in the less productive lakes. Predictive models to estimate TP from species abundance data were developed using weighted averaging techniques. This research has produced strong and significant inference models, which can now be used to reconstruct past changes in lake trophic status from remains of Cladocera in sediment cores.
The risk of running on empty: the influence of age on starvation and gut fullness in larval Atlantic cod (Gadus morhua)
Authors: Jordaan Adrian , Brown Joseph A
Published: November 2003

Two experiments were set up to evaluate whether the response of Atlantic cod (Gadus morhua) larvae to no-prey conditions changes with age. The first experiment was designed to test for age-specific starvation with starvation trials at 0, 5, 15, 30, and 45 days after hatching. Mortality, length, and swimming activity data were collected. A second experiment was conducted to determine the effect of non-feeding conditions on the residency of prey in the gut at 5, 15, 30, and 45 days after hatching. The results of experiment 1 indicated that mortality occurred most rapidly at 15 and 30 days and was delayed during the yolk-sac period (day 0). Larvae in non-fed treatments showed significantly lower activity levels, except in the 45-day treatment, and the reduction in activity occurred before the onset of mortality. In experiment 2, gut residencies displayed an age-dependent response, with 5- and 45-day-old larvae having significantly shorter residency times. We conclude that beyond the yolk-sac period, cod larvae exhibit an age-dependent trade-off between growth and starvation risk. Larval age also influences patterns of gut fullness over time, with the fastest rates of gut clearance found at first-feeding and metamorphosis.
Unexpected patterns of mitochondrial DNA variation among Native Americans from the Southeastern United States
Authors: (Weiss) Bolnick Deborah A. , Smith David Glenn
Published: November 2003

Mitochondrial DNA (mtDNA) haplogroups were determined by restriction fragment length polymorphism‐typing for 66 individuals from four southeastern North American populations, and the HVS I portion of the mtDNA control region was sequenced in 48 of these individuals. Although populations from the same geographic region usually exhibit similar haplogroup frequency distributions (Lorenz and Smith [1996] Am. J. Phys. Anthropol.101:307–323; Malhi et al. [2001] Hum. Biol.73:17–55), those from the Southeast instead exhibit haplogroup frequency distributions that differ significantly from one another. Such divergent haplogroup frequency distributions are unexpected for the Muskogean‐speaking southeastern populations, which share many sociocultural traits, speak closely related languages, and have experienced extensive admixture both with each other and with other eastern North American populations. Independent origins, genetic isolation from other Native American populations due to matrilocality, differential admixture, or a genetic bottleneck could be responsible for this heterogeneous distribution of haplogroup frequencies. Within a given haplogroup, however, the HVS I sequences from the four Muskogean‐speaking populations appear relatively similar to one another, providing evidence for close relationships among them and for reduced diversity within haplogroups in the Southeast. Given additional archaeological, linguistic, and ethnographic evidence, these results suggest that a genetic bottleneck associated with the historical population decline is the most plausible explanation for such patterns of mtDNA variation. Am J Phys Anthropol, 2003. © 2003 Wiley‐Liss, Inc.
Sedimentation rates in the lower Yellow River over the past 2300 years as influenced by human activities and climate change
Authors: Xu Jiongxin
Published: November 2003

Analysis of the sedimentary record has been used to determine the historical sedimentation rate in the lower Yellow River and the historical literature has been studied to obtain information on climate change and human activities. Based on the data obtained, the temporal variation in the sedimentation rate in the lower Yellow River over the past 2300 years has been studied in relation to climate change and the impact of human activities. The results indicate that the response of the sedimentation zone of Yellow River system to changes in the erosion zone are consistent with existing understanding. Changes in vegetation and land use, both related to climate change and human activities, are two major controls responsible for the increase in sedimentation rates. Additionally, the changing strategies for harnessing of the lower Yellow River are also responsible for such acceleration. With the trend of accelerated sedimentation in the past 2300 years, the period from the 7th to 10th centuries and the period since the mid‐19th century have been identified as two periods in which abrupt changes occurred. Copyright © 2003 John Wiley & Sons, Ltd.
Bisphosphonate treatment affects trabecular bone apparent modulus through micro‐architecture rather than matrix properties
Authors: Day J. S. , Ding M. , Bednarz P. , van der Linden J. C. , Mashiba T. , Hirano T. , Johnston C. C. , Burr D. B. , Hvid I. , Sumner D. R. , Weinans H.
Published: November 2003

Bisphosphonates are emerging as an important treatment for osteoporosis. But whether the reduced fracture risk associated with bisphosphonate treatment is due to increased bone mass, improved trabecular architecture and/or increased secondary mineralization of the calcified matrix remains unclear. We examined the effects of bisphosphonates on both the trabecular architecture and matrix properties of canine trabecular bone. Thirty‐six beagles were divided into a control group and two treatment groups, one receiving risedronate and the other alendronate at 5–6 times the clinical dose for osteoporosis treatment. After one year, the dogs were killed, and samples from the first lumbar vertebrae were examined using a combination of micro‐computed tomography, finite element modeling, and mechanical testing. By combining these methods, we examined the treatment effects on the calcified matrix and trabecular architecture independently. Conventional histomorphometry and microdamage data were obtained from the second and third lumbar vertebrae of the same dogs [Bone 28 (2001) 524]. Bisphosphonate treatment resulted in an increased apparent Young's modulus, decreased bone turnover, increased calcified matrix density, and increased microdamage. We could not detect any change in the effective Young's modulus of the calcified matrix in the bisphosphonate treated groups. The observed increase in apparent Young's modulus was due to increased bone mass and altered trabecular architecture rather than changes in the calcified matrix modulus. We hypothesize that the expected increase in the Young's modulus of the calcified matrix due to the increased calcified matrix density was counteracted by the accumulation of microdamage. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Predicting stress fractures using a probabilistic model of damage, repair and adaptation
Authors: Taylor David , Casolari Edoardo , Bignardi Cristina
Published: November 2003

This paper is concerned with the theoretical prediction of stress fractures in the bones of athletes, soldiers and others during periods of intensive exercise. Previously [J. Orthop. Res. 19 (2001) 919] we showed that test data on the fatigue strength of bone in vitro could be described using Weibull's probabilistic model, allowing predictions to be made of the probability of failure as a function of time under cyclic loading. This paper extends the earlier argument by including two living processes which act to reduce the incidence of failure: (i) repair of damage, and; (ii) adaptation by bone deposition. Having incorporated these aspects into the mathematical model, we applied the theory to a specific case: the human second metatarsal. We predicted a 17% incidence of stress fractures, all occurring within 6 weeks of commencement of the training programme. These predictions agreed well with clinical findings. Interestingly, we concluded that the major effect in preventing stress fractures comes from repair rather than from adaptation, which has a relatively minor role because it acts more slowly. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Tibio‐femoral loading during human gait and stair climbing
Authors: Taylor William R. , Heller Markus O. , Bergmann Georg , Duda Georg N.
Published: November 2003

Surgical intervention of the knee joint routinely endeavors to recreate a physiologically normal joint loading environment. The loading conditions resulting from osteotomies, fracture treatment, ligament replacements, and arthroplasties of the knee are considered to have an impact on the long term clinical outcome; however, knowledge regarding in vivo loading conditions is limited. Using a previously validated musculoskeletal lower limb model, we predicted the tibio‐femoral joint contact forces that occur in the human knee during the common daily activities of walking and stair climbing. The average resultant peak force during walking was 3.1 times body weight (BW) across four total hip arthroplasty patients. Inter‐individual variations proved larger than the variation of forces for each patient repeating the same task. Forces through the knee were considerably larger during stair climbing than during walking: the average resultant peak force during stair climbing was 5.4 BW although peaks of up to 6.2 BW were calculated for one particular patient. Average anteroposterior peak shear components of 0.6 BW were determined during walking and 1.3 BW during stair climbing. These results confirm both the joint contact forces reported in the literature and the importance of muscular activity in creating high forces across the joint. The magnitudes of these forces, specifically in shear, have implications for all forms of surgical intervention in the knee. The data demonstrate that high contact and shear forces are generated during weight bearing combined with knee flexion angles greater than approximately 15°. Clinically, the conditions that produce these larger contact forces should be avoided during post‐operative rehabilitation. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Bone sialoprotein‐coated femoral implants are osteoinductive but mechanically compromised
Authors: O'Toole Gary C. , Salih E. , Gallagher C. , FitzPatrick D. , O'Higgins N. , O'Rourke S. K.
Published: November 2003

Aseptic loosening of femoral implants in total hip replacement remains an unsolved orthopaedic problem. This paper investigates the potential role of bone sialoprotein (BSP) in enhancing bone‐implant adherence. As BSP is osteoinductive in rat calvarial models, we investigated whether BSP is similarly osteoinductive when coated onto intramedullary femoral implants.

BSP‐coated titanium implants were implanted into the femur of female “Wistar” rats (average weight 215 g) that were sacrificed at days 10, 20 and 30. Harvested femoral implants were subjected to pullout testing and then examined histologically.

BSP‐coated implants demonstrate osteoinduction when examined histologically. Plugging the femoral canal with BSP prior to inserting the implant neither increased implant pullout strengths nor further increased osteoblastic activity.

This study has demonstrated for the first time that BSP is osteoinductive when coated onto femoral implants and inserted into bones subjected to mechanical loading. However, we found that pullout strengths are a function of implant surface topographical characteristics and are not affected by BSP coating or histological osteoinduction. © 2003 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Relative biological effectiveness (RBE), quality factor (Q), and radiation weighting factor (wR)
Authors: Valentin J.
Published: November 2003

The effect of ionising radiation is influenced by the dose, the dose rate, and the quality of the radiation. Before 1990, dose-equivalent quantities were defined in terms of a quality factor, Q( L), that was applied to the absorbed dose at a point in order to take into account the differences in the effects of different types of radiation. In its 1990 recommendations, the ICRP introduced a modified concept. For radiological protection purposes, the absorbed dose is averaged over an organ or tissue, T, and this absorbed dose average is weighted for the radiation quality in terms of the radiation weighting factor, w R, for the type and energy of radiation incident on the body. The resulting weighted dose is designated as the organ- or tissue-equivalent dose, H T. The sum of the organ-equivalent doses weighted by the ICRP organ-weighting factors, w T, is termed the effective dose, E. Measurements can be performed in terms of the operational quantities, ambient dose equivalent, and personal dose equivalent. These quantities continue to be defined in terms of the absorbed dose at the reference point weighted by Q( L).

The values for w R and Q( L) in the 1990 recommendations were based on a review of the biological and other information available, but the underlying relative biological effectiveness (RBE) values and the choice of w R values were not elaborated in detail. Since 1990, there have been substantial developments in biological and dosimetric knowledge that justify a re-appraisal of w R values and how they may be derived.

This re-appraisal is the principal objective of the present report. The report discusses in some detail the values of RBE with regard to stochastic effects, which are central to the selection of w R and Q( L). Those factors and the dose-equivalent quantities are restricted to the dose range of interest to radiation protection, i.e. to the general magnitude of the dose limits. In special circumstances where one deals with higher doses that can cause deterministic effects, the relevant RBE values are applied to obtain a weighted dose. The question of RBE values for deterministic effects and how they should be used is also treated in the report, but it is an issue that will demand further investigations.

This report is one of a set of documents being developed by ICRP Committees in order to advise the ICRP on the formulation of its next Recommendations for Radiological Protection. Thus, while the report suggests some future modifications, the w R values given in the 1990 recommendations are still valid at this time. The report provides a scientific background and suggests how the ICRP might proceed with the derivation of w R values ahead of its forthcoming recommendations.
Role of interleukin‐2 and interferon‐γ in inducing production of IgG subclasses in lymphocytes of human newborns
Authors: KAWANO Y. , NOMA T.
Published: November 2003

Unlike lymphocytes from adults, lymphocytes from cord blood of neonates cannot synthesize immunoglobulin G (IgG) in response to pokeweed mitogen (PWM). By using this mitogen in concert with interferon‐γ (IFN‐γ), interleukin‐2 (IL‐2), or interleukin‐6 (IL‐6), we studied the induction of IgG subclass molecules in lymphocytes of human neonates. IFN‐γ induced a limited, but substantial, enhancement of IgG2 production by neonatal lymphocytes. IL‐2 dose dependently increased the production of each neonatal IgG subclass, whereas IL‐6 did not. However, in adult lymphocytes, and under specific conditions, IL‐6 or IL‐2 each increased the production of all four IgG subclasses. Early in the culture IFN‐γ synergized with IL‐2 during the latter or whole culture period to enhance cord blood IgG2 levels. This finding contrasted with the adult IgG2 synthesis synergistically up‐regulated by IFN‐γ and IL‐6. IL‐2 caused a graded increase in immunoglobulin production in neonatal lymphocytes with IgG3 being the highest and IgG2 the lowest, thus corresponding to the differential increase of serum levels of IgG3/IgG1 and IgG4/IgG2 early in childhood. Results suggest that IL‐2, but not IL‐6, is critical to the development of human IgG subclass production.