bluuebunny/crossref_metadata_2025 huggingface dataset:
Within-individual variation in bullfrog vocalizations: Implications for a vocally mediated social recognition system
Authors: Bee Mark A.
Published: December 2004

Acoustic signals provide a basis for social recognition in a wide range of animals. Few studies, however, have attempted to relate the patterns of individual variation in signals to behavioral discrimination thresholds used by receivers to discriminate among individuals. North American bullfrogs (Rana catesbeiana) discriminate among familiar and unfamiliar individuals based on individual variation in advertisement calls. The sources, patterns, and magnitudes of variation in eight acoustic properties of multiple-note advertisement calls were examined to understand how patterns of within-individual variation might either constrain, or provide additional cues for, vocal recognition. Six of eight acoustic properties exhibited significant note-to-note variation within multiple-note calls. Despite this source of within-individual variation, all call properties varied significantly among individuals, and multivariate analyses indicated that call notes were individually distinct. Fine-temporal and spectral call properties exhibited less within-individual variation compared to gross-temporal properties and contributed most toward statistically distinguishing among individuals. Among-individual differences in the patterns of within-individual variation in some properties suggest that within-individual variation could also function as a recognition cue. The distributions of among-individual and within-individual differences were used to generate hypotheses about the expected behavioral discrimination thresholds of receivers.
High-sensitivity piezoelectric microphones based on stacked cellular polymer films (L)
Authors: Hillenbrand Joachim , Sessler Gerhard M.
Published: December 2004

Improvements of the sensitivity of piezoelectric microphones based on charged cellular polymer films are reported. The improvements are achieved by (1) an increase of the piezoelectric d33-coefficient of the cellular polypropylene films by pressure expansion and (2) stacking of the films. Microphones consisting of a single film of such material have sensitivities of about 2 mV/Pa at 1 kHz, independent of size, while for a microphone with five stacked films a sensitivity of 10.5 mV/Pa was measured. The equivalent noise level is about 37 dB(A) for the single-film transducer and 26 dB(A) for the stacked version. Advantages of these new piezoelectric transducers include their simple design, low cost, and small weight, as well as a large range of shapes and sizes possible.
The role of noise sensitivity in the noise–response relation: A comparison of three international airport studies
Authors: van Kamp Irene , Job R. F. Soames , Hatfield Julie , Haines Mary , Stellato Rebecca K. , Stansfeld Stephen A.
Published: December 2004

In order to examine the role of noise sensitivity in response to environmental noise, this paper presents detailed comparisons of socio-acoustic studies conducted around international airports in Amsterdam, Sydney, and London. Earlier findings that noise sensitivity moderates the effect of noise on annoyance were examined to see if they could be replicated in each of the datasets, independent of the technique of measuring noise sensitivity. The relation between exposure to aircraft noise and noise annoyance was studied separately for groups of individuals with low, medium, and high noise sensitivity, with statistical adjustment for relevant confounders. Results support the previous findings that noise sensitivity is an independent predictor of annoyance and adds to the prediction of noise annoyance afforded by noise exposure level by up to 26% of explained variance. There is no evidence of a moderating effect, whereby the covariation between noise exposure level and annoyance is weak for people who score at the extreme high or low end of the sensitivity scale, and strong for people who score in the middle of the sensitivity scale. Generally, noise sensitivity appears to increase annoyance independently of the level of noise exposure after adjustment for relevant confounders. These findings were consistent across the three datasets.
Patterns of English phoneme confusions by native and non-native listeners
Authors: Cutler Anne , Weber Andrea , Smits Roel , Cooper Nicole
Published: December 2004

Native American English and non-native (Dutch) listeners identified either the consonant or the vowel in all possible American English CV and VC syllables. The syllables were embedded in multispeaker babble at three signal-to-noise ratios (0, 8, and 16 dB). The phoneme identification performance of the non-native listeners was less accurate than that of the native listeners. All listeners were adversely affected by noise. With these isolated syllables, initial segments were harder to identify than final segments. Crucially, the effects of language background and noise did not interact; the performance asymmetry between the native and non-native groups was not significantly different across signal-to-noise ratios. It is concluded that the frequently reported disproportionate difficulty of non-native listening under disadvantageous conditions is not due to a disproportionate increase in phoneme misidentifications.
Habitat-dependent ambient noise: Consistent spectral profiles in two African forest types
Authors: Slabbekoorn Hans
Published: December 2004

Many animal species use acoustic signals to attract mates, to defend territories, or to convey information that may contribute to their fitness in other ways. However, the natural environment is usually filled with competing sounds. Therefore, if ambient noise conditions are relatively constant, acoustic interference can drive evolutionary changes in animal signals. Furthermore, masking noise may cause acoustic divergence between populations of the same species if noise conditions differ consistently among habitats. In this study, ambient noise was sampled in a replicate set of sites in two habitat types in Cameroon: contiguous rainforest and ecotone forest patches north of the rainforest. The noise characteristics of the two forest types show significant and consistent differences. Multiple samples taken at two rainforest sites in different seasons vary little and remain distinct from those in ecotone forest. The rainforest recordings show many distinctive frequency bands, with a general increase in amplitude from low to high frequencies. Ecotone forest only shows a distinctive high-frequency band at some parts of the day. Habitat-dependent abiotic and biotic sound sources and to some extent habitat-dependent sound transmission are the likely causes of these habitat-dependent noise spectra.
Measurement of in-duct acoustic properties by using a single microphone with fixed position
Authors: Choy Y. S. , Huang Lixi
Published: December 2004

Acoustic properties of sound absorption materials and other acoustic structures can be measured in an impedance tube using the well-established two-microphone method to resolve the two traveling wave components of a standing wave pattern. The accuracy of such measurements depends crucially on the calibration of the two microphones placed in close proximity. To eliminate such calibration, the one-microphone method [Chu, J. Acoust. Soc. Am. 80, 555–560 (1986)] uses the same microphone to probe at two positions sequentially using the voltage driving the loudspeaker as a reference signal. A variant of this method is introduced in this study in which the microphone is fixed at one position while a rigid end plate moves between two positions to resolve the standing wave. The sound source is installed as a side branch, and its driving signal is also used as a reference in the two-step measurement. Close agreement is found with the established two-microphone method, and factors which might affect the accuracy of the new technique are discussed. As a demonstration of the robustness of the method, a low-budget electret microphone is used and the result also matches well with those obtained by the two-microphone method with high-quality condenser type microphones.
Measurement of viscoelastic properties of homogeneous soft solid using transient elastography: An inverse problem approach
Authors: Catheline S. , Gennisson J.-L. , Delon G. , Fink M. , Sinkus R. , Abouelkaram S. , Culioli J.
Published: December 2004

Two main questions are at the center of this paper. The first one concerns the choice of a rheological model in the frequency range of transient elastography, sonoelasticity or NMR elastography for soft solids (20–1000 Hz). Transient elastography experiments based on plane shear waves that propagate in an Agar-gelatin phantom or in bovine muscles enable one to quantify their viscoelastic properties. The comparison of these experimental results to the prediction of the two simplest rheological models indicate clearly that Voigt’s model is the better. The second question studied in the paper deals with the feasibility of quantitative viscosity mapping using inverse problem algorithm. In the ideal situation where plane shear waves propagate in a sample, a simple inverse problem based on the Helmholtz equation correctly retrieves both elasticity and viscosity. In a more realistic situation with nonplane shear waves, this simple approach fails. Nevertheless, it is shown that quantitative viscosity mapping is still possible if one uses an appropriate inverse problem that fully takes into account diffraction in solids.
A numerical study of the role of the tragus in the big brown bat
Authors: Müller Rolf
Published: December 2004

A comprehensive characterization of the spatial sensitivity of an outer ear from a big brown bat (Eptesicus fuscus) has been obtained using numerical methods and visualization techniques. Pinna shape information was acquired through x-ray microtomography. It was used to set up a finite-element model of diffraction from which directivities were predicted by virtue of forward wave-field projections based on a Kirchhoff integral formulation. Digital shape manipulation was used to study the role of the tragus in detailed numerical experiments. The relative position between tragus and pinna aperture was found to control the strength of an extensive asymmetric sidelobe which points in a frequency-dependent direction. An upright tragus position resulted in the strongest sidelobe sensitivity. Using a bootstrap validation paradigm, the results were found to be robust against small perturbations of the finite-element mesh boundaries. Furthermore, it was established that a major aspect of the tragus effect (position dependence) can be studied in a simple shape model, an obliquely truncated horn augmented by a flap representing the tragus. In the simulated wave field around the outer-ear structure, strong correlates of the tragus rotation were identified, which provide a direct link to the underlying physical mechanism.
Eigenmodes of triaxial ellipsoidal acoustical cavities with mixed boundary conditions
Authors: Willatzen M. , Lew Yan Voon L. C.
Published: December 2004

The linear acoustics problem of resonant vibrational modes in a triaxial ellipsoidal acoustic cavity with walls of arbitrary acoustic impedance has been quasi-analytically solved using the Frobenius power-series expansion method. Eigenmode results are presented for the lowest two eigenmodes in cases with pressure-release, rigid-wall, and lossy-wall boundary conditions. A mode crossing is obtained as a function of the specific acoustic impedance of the wall; the degeneracy is not symmetry related. Furthermore, the damping of the wave is found to be maximal near the crossing.
Transient propagation in media with classical or power-law loss
Authors: Cobbold Richard S. C. , Sushilov Nikolai V. , Weathermon Adam C.
Published: December 2004

This paper addresses the problem of small-signal transient wave propagation in media whose absorption coefficient obeys power-law frequency dependence, i.e., α∝ωn. Our approach makes use of previously derived relations between the absorption and dispersion based on the Kramers–Kronig relations. This, combined with a recently obtained solution to a causal convolution wave equation enable expressions to be obtained for one-dimensional transient propagation when n is in the range 0<n<3. For n=2, corresponding to no dispersion, straightforward analytical expressions are obtained for a δ-function and a sinusoidal step function sources and these are shown to correspond to relations previously derived. For other values of n, the effects of dispersion are accounted for by using Fourier transforms. Examples are used to illustrate the results for normal and anomalous dispersive media and to examine the question as to the conditions under which the effects of dispersion should be accounted for, especially for wideband ultrasound pulses of the type used in B-mode tissue imaging. It is shown that the product of the attenuation and total propagation path can be used as a criterion for judging whether dispersion needs to be accounted for.
Relative contributions of temporal and place pitch cues to fundamental frequency discrimination in cochlear implantees
Authors: Laneau Johan , Wouters Jan , Moonen Marc
Published: December 2004

The effect of the filter bank on fundamental frequency (F0) discrimination was examined in four Nucleus CI24 cochlear implant subjects for synthetic stylized vowel-like stimuli. The four tested filter banks differed in cutoff frequencies, amount of overlap between filters, and shape of the filters. To assess the effects of temporal pitch cues on F0 discrimination, temporal fluctuations were removed above 10 Hz in one condition and above 200 Hz in another. Results indicate that F0 discrimination based upon place pitch cues is possible, but just-noticeable differences exceed 1 octave or more depending on the filter bank used. Increasing the frequency resolution in the F0 range improves the F0 discrimination based upon place pitch cues. The results of F0 discrimination based upon place pitch agree with a model that compares the centroids of the electrical excitation pattern. The addition of temporal fluctuations up to 200 Hz significantly improves F0 discrimination. Just-noticeable differences using both place and temporal pitch cues range from 6% to 60%. Filter banks that do not resolve the higher harmonics provided the best temporal pitch cues, because temporal pitch cues are clearest when the fluctuation on all channels is at F0 and preferably in phase.
Endogenous Lipogenic Regulators of Spore Balance in
Aspergillus nidulans
Authors: Tsitsigiannis Dimitrios I. , Kowieski Terri M. , Zarnowski Robert , Keller Nancy P.
Published: December 2004

The ability of fungi to produce both meiospores and mitospores has provided adaptive advantages in survival and dispersal of these organisms. Here we provide evidence of an endogenous mechanism that balances meiospore and mitospore production in the model filamentous fungus
Aspergillus nidulans
. We have discovered a putative dioxygenase, PpoC, that functions in association with a previously characterized dioxygenase, PpoA, to integrate fatty acid derived oxylipin and spore production. In contrast to PpoA, deletion of
ppoC
significantly increased meiospore production and decreased mitospore development. Examination of the PpoA and PpoC mutants indicate that this ratio control is associated with two apparent feedback loops. The first loop shows
ppoC
and
ppoA
expression is dependent upon, and regulates the expression of,
nsdD
and
brlA
, genes encoding transcription factors required for meiospore or mitospore production, respectively. The second loop suggests Ppo oxylipin products antagonistically signal the generation of Ppo substrates. These data support a case for a fungal “oxylipin signature-profile” indicative of relative sexual and asexual spore differentiation.
KRE5Gene Null Mutant Strains ofCandida albicansAre Avirulent and Have Altered Cell Wall Composition and Hypha Formation Properties
Authors: Herrero Ana B. , Magnelli Paula , Mansour Michael K. , Levitz Stuart M. , Bussey Howard , Abeijon Claudia
Published: December 2004

The UDP-glucose:glycoprotein glucosyltransferase (UGGT) is an endoplasmic reticulum sensor for quality control of glycoprotein folding.Saccharomyces cerevisiaeis the only eukaryotic organism so far described lacking UGGT-mediated transient reglucosylation of N-linked oligosaccharides. The only gene inS. cerevisiaewith similarity to those encoding UGGTs isKRE5. S. cerevisiae KRE5deletion strains show severely reduced levels of cell wall β-1,6-glucan polymer, aberrant morphology, and extremely compromised growth or lethality, depending on the strain background. Deletion of both alleles of theCandida albicans KRE5gene gives rise to viable cells that are larger than those of the wild type (WT), tend to aggregate, have enlarged vacuoles, and show major cell wall defects.C. albicans kre5/kre5mutants have significantly reduced levels of β-1,6-glucan and more chitin and β-1,3-glucan and less mannoprotein than the WT. The remaining β-1,6-glucan, about 20% of WT levels, exhibits a β-1,6-endoglucanase digestion pattern, including a branch point-to-linear stretch ratio identical to that of WT strains, suggesting that Kre5p is not a β-1,6-glucan synthase.C. albicans KRE5is a functional homologue ofS. cerevisiae KRE5; it partially complements both the growth defect and reduced cell wall β-1,6-glucan content ofS. cerevisiae kre5viable mutants.C. albicans kre5/kre5homozygous mutant strains are unable to form hyphae in several solid and liquid media, even in the presence of serum, a potent inducer of the dimorphic transition. Surprisingly the mutants do form hyphae in the presence ofN-acetylglucosamine. Finally,C. albicans KRE5homozygous mutant strains exhibit a 50% reduction in adhesion to human epithelial cells and are completely avirulent in a mouse model of systemic infection.
Adenylyl Cyclase-Associated Protein Aca1 Regulates Virulence and Differentiation of
Cryptococcus neoformans
via the Cyclic AMP-Protein Kinase A Cascade
Authors: Bahn Yong-Sun , Hicks Julie K. , Giles Steven S. , Cox Gary M. , Heitman Joseph
Published: December 2004

The evolutionarily conserved cyclic AMP (cAMP) signaling pathway controls cell functions in response to environmental cues in organisms as diverse as yeast and mammals. In the basidiomycetous human pathogenic fungus
Cryptococcus neoformans
, the cAMP pathway governs virulence and morphological differentiation. Here we identified and characterized adenylyl cyclase-associated protein, Aca1, which functions in parallel with the Gα subunit Gpa1 to control the adenylyl cyclase (Cac1). Aca1 interacted with the C terminus of Cac1 in the yeast two-hybrid system. By molecular and genetic approaches, Aca1 was shown to play a critical role in mating by regulating cell fusion and filamentous growth in a cAMP-dependent manner. Aca1 also regulates melanin and capsule production via the Cac1-cAMP-protein kinase A pathway. Genetic epistasis studies support models in which Aca1 and Gpa1 are necessary and sufficient components that cooperate to activate adenylyl cyclase. Taken together, these studies further define the cAMP signaling cascade controlling virulence of this ubiquitous human fungal pathogen.
Increased Genome Instability and Telomere Length in the
elg1
-Deficient
Saccharomyces cerevisiae
Mutant Are Regulated by S-Phase Checkpoints
Authors: Banerjee Soma , Myung Kyungjae
Published: December 2004

Gross chromosomal rearrangements (GCRs) are frequently observed in cancer cells. Abnormalities in different DNA metabolism including DNA replication, cell cycle checkpoints, chromatin remodeling, telomere maintenance, and DNA recombination and repair cause GCRs in
Saccharomyces cerevisiae
. Recently, we used genome-wide screening to identify several genes the deletion of which increases GCRs in
S. cerevisiae
. Elg1, which was discovered during this screening, functions in DNA replication by participating in an alternative replication factor complex. Here we further characterize the GCR suppression mechanisms observed in the
elg1
Δ mutant strain in conjunction with the telomere maintenance role of Elg1. The
elg1
Δ mutation enhanced spontaneous DNA damage and resulted in GCR formation. However, DNA damage due to inactivation of Elg1 activates the intra-S checkpoints, which suppress further GCR formation. The intra-S checkpoints activated by the
elg1
Δ mutation also suppress GCR formation in strains defective in the DNA replication checkpoint. Lastly, the
elg1
Δ mutation increases telomere size independently of other previously known telomere maintenance proteins such as the telomerase inhibitor Pif1 or the telomere size regulator Rif1. The increase in telomere length caused by the
elg1
Δ mutation was suppressed by a defect in the DNA replication checkpoint, which suggests that DNA replication surveillance by Dpb11-Mec1/Tel1-Dun1 also has an important role in telomere length regulation.
Rad51 Protein from the Thermotolerant Yeast
Pichia angusta
as a Typical but Thermodependent Member of the Rad51 Family
Authors: Shalguev Valery I. , Kil Yury V. , Yurchenko Ludmila V. , Namsaraev Eugene A. , Lanzov Vladislav A.
Published: December 2004

The Rad51 protein from the methylotrophic yeast
Pichia angusta
(Rad51
Pa
) of the taxonomic complex
Hansenula polymorpha
is a homolog of the RecA-RadA-Rad51 protein superfamily, which promotes homologous recombination and recombination repair in prokaryotes and eukaryotes. We cloned the
RAD51
gene from the cDNA library of the thermotolerant
P. angusta
strain BKM Y1397. Induction of this gene in a
rad51
-deficient
Saccharomyces cerevisiae
strain partially complemented the survival rate after ionizing radiation. Purified Rad51
Pa
protein exhibited properties typical of the superfamily, including the stoichiometry of binding to single-stranded DNA (ssDNA) (one protomer of Rad51
Pa
per 3 nucleotides) and DNA specificity for ssDNA-dependent ATP hydrolysis [poly(dC) > poly(dT) > φX174 ssDNA > poly(dA) > double-stranded M13 DNA]. An inefficient ATPase and very low cooperativity for ATP interaction position Rad51
Pa
closer to Rad51 than to RecA. Judging by thermoinactivation, Rad51
Pa
alone was 20-fold more thermostable at 37°C than its
S. cerevisiae
homolog (Rad51
Sc
). Moreover, it maintained ssDNA-dependent ATPase and DNA transferase activities up to 52 to 54°C, whereas Rad51
Sc
was completely inactive at 47°C. A quick nucleation and an efficient final-product formation in the strand exchange reaction promoted by Rad51
Pa
occurred only at temperatures above 42°C. These reaction characteristics suggest that Rad51
Pa
is dependent on high temperatures for activity.
UGD1
, Encoding the
Cryptococcus neoformans
UDP-Glucose Dehydrogenase, Is Essential for Growth at 37°C and for Capsule Biosynthesis
Authors: Moyrand Frédérique , Janbon Guilhem
Published: December 2004

We report the identification and disruption of the
Cryptococcus neoformans
var.
grubii UGD1
gene encoding the UDP-glucose dehydrogenase, which catalyzes the conversion of UDP-glucose into UDP-glucuronic acid. Deletion of
UGD1
led to modifications in the cell wall, as revealed by changes in the sensitivity of
ugd1
Δ cells to sodium dodecyl sulfate, NaCl, and sorbitol. Moreover, two of the yeast's major virulence factors—capsule biosynthesis and the ability to grow at 37°C—were impaired in
ugd1
Δ strains. These results suggest that the UDP-dehydrogenase represents the major, and maybe only, biosynthetic pathway for UDP-glucuronic acid in
C. neoformans
. Consequently, deletion of
UGD1
blocked not only the synthesis of UDP-glucuronic acid but also that of UDP-xylose. To differentiate the phenotype(s) associated with the UDP-glucuronic acid defect alone from those linked to the UDP-xylose defect,
ugd1
Δ mutants were phenotypically compared to strains from which the gene encoding UDP-xylose synthase (i.e., that required for synthesis of UDP-xylose) had been deleted. Finally, studies of strains from which one of the four
CAP
genes (
CAP10
,
CAP59
,
CAP60
, or
CAP64
) had been deleted revealed common cell wall phenotypes associated with the acapsular state.
The Small-Subunit Processome Is a Ribosome Assembly Intermediate
Authors: Bernstein Kara A. , Gallagher Jennifer E. G. , Mitchell Brianna M. , Granneman Sander , Baserga Susan J.
Published: December 2004

The small-subunit (SSU) processome is a large ribonucleoprotein required for the biogenesis of the 18S rRNA and likely corresponds to the terminal knobs visualized by electron microscopy on the 5′ end of nascent rRNAs. The original purification of the SSU processome of
Saccharomyces cerevisiae
resulted in the identification of 28 proteins. Here, we characterize 12 additional protein components, including five small-ribosomal-subunit proteins (Rps4, Rps6, Rps7, Rps9, and Rps14) that had previously been copurified. Our multiple criteria for including a component as a bona fide SSU processome component included coimmunoprecipitation with Mpp10 (an SSU processome component), the U3 snoRNA, and the anticipated pre-rRNAs. Importantly, the association of specific ribosomal proteins with the SSU processome suggests that the SSU processome has roles in both pre-rRNA processing and ribosome assembly. These ribosomal proteins may be analogous to the primary or secondary RNA binding proteins first described in bacterial in vitro ribosome assembly maps. In addition to the ribosomal proteins and based on the same experimental approach, we found seven other proteins (Utp18, Noc4, Utp20, Utp21, Utp22, Emg1, and Krr1) to be bona fide SSU processome proteins.
TAC1
, Transcriptional Activator of
CDR
Genes, Is a New Transcription Factor Involved in the Regulation of
Candida albicans
ABC Transporters
CDR1
and
CDR2
Authors: Coste Alix T. , Karababa Mahir , Ischer Françoise , Bille Jacques , Sanglard Dominique
Published: December 2004

The ABC transporter genes
CDR1
and
CDR2
can be upregulated in
Candida albicans
developing resistance to azoles or can be upregulated by exposing cells transiently to drugs such as fluphenazine. The
cis
-acting drug-responsive element (DRE) present in the promoters of both genes and necessary for their upregulation contains 5′-CGG-3′ triplets that are often recognized by transcriptional activators with Zn(2)-Cys(6) fingers. In order to isolate regulators of
CDR1
and
CDR2
, the
C. albicans
genome was searched for genes encoding proteins with Zn(2)-Cys(6) fingers. Interestingly, three of these genes were tandemly arranged near the mating locus. Their involvement in
CDR1
and
CDR2
upregulation was addressed because a previous study demonstrated a link between mating locus homozygosity and azole resistance. The deletion of only one of these genes (orf19.3188) was sufficient to result in a loss of transient
CDR1
and
CDR2
upregulation by fluphenazine and was therefore named
TAC1
(transcriptional activator of
CDR
genes). Tac1p has a nuclear localization, and a fusion of Tac1p with glutathione
S
-transferase could bind the
cis
-acting regulatory DRE in both the
CDR1
and the
CDR2
promoters.
TAC1
is also relevant for azole resistance, since a
TAC1
allele (
TAC1-2
) recovered from an azole-resistant strain could trigger constitutive upregulation of
CDR1
and
CDR2
in an azole-susceptible laboratory strain. Transcript profiling experiments performed with a
TAC1
mutant and a revertant containing
TAC1-2
revealed not only
CDR1
and
CDR2
as targets of
TAC1
regulation but also other genes (
RTA3
,
IFU5
, and
HSP12
) that interestingly contained a DRE-like element in their promoters. In conclusion,
TAC1
appears to be the first
C. albicans
transcription factor involved in the control of genes mediating antifungal resistance.
Rabbit and Nonhuman Primate Models of Toxin-Targeting Human Anthrax Vaccines
Authors: Phipps Andrew J. , Premanandan Christopher , Barnewall Roy E. , Lairmore Michael D.
Published: December 2004

The intentional use ofBacillus anthracis, the etiological agent of anthrax, as a bioterrorist weapon in late 2001 made our society acutely aware of the importance of developing, testing, and stockpiling adequate countermeasures against biological attacks. Biodefense vaccines are an important component of our arsenal to be used during a biological attack. However, most of the agents considered significant threats either have been eradicated or rarely infect humans alive today. As such, vaccine efficacy cannot be determined in human clinical trials but must be extrapolated from experimental animal models. This article reviews the efficacy and immunogenicity of human anthrax vaccines in well-defined animal models and the progress toward developing a rugged immunologic correlate of protection. The ongoing evaluation of human anthrax vaccines will be dependent on animal efficacy data in the absence of human efficacy data for licensure by the U.S. Food and Drug Administration.
Little Lambda, Who Made Thee?
Authors: Gottesman Max E. , Weisberg Robert A.
Published: December 2004

The study of the bacteriophage λ has been critical to the discipline of molecular biology. It was the source of key discoveries in the mechanisms of, among other processes, gene regulation, recombination, and transcription initiation and termination. We trace here the events surrounding these findings and draw on the recollections of the participants. We show how a particular atmosphere of interactions among creative scientists yielded spectacular insights into how living things work.
BOUND AND SCATTERING STATES OF ITINERANT CHARGE CARRIERS IN COMPLEX MAGNETIC MATERIALS
Authors: KUZEMSKY A. L.
Published: December 2004

The concept of magnetic polaron is analyzed and developed to elucidate the nature of itinerant charge carrier states in magnetic semiconductors and similar complex magnetic materials. By contrasting the scattering and bound states of carriers within the s–d exchange model, the nature of bound states at finite temperatures is clarified. The free magnetic polaron at certain conditions is realized as a bound state of the carrier (electron or hole) with the spin wave. Quite generally, a self-consistent theory of a magnetic polaron is formulated within a nonperturbative many-body approach, the Irreducible Green Functions (IGF) method which is used to describe the quasiparticle many-body dynamics at finite temperatures. Within the above many-body approach we elaborate a self-consistent picture of dynamic behavior of two interacting subsystems, the localized spins and the itinerant charge carriers. In particular, we show that the relevant generalized mean fields emerges naturally within our formalism. At the same time, the correct separation of elastic scattering corrections permits one to consider the damping effects (inelastic scattering corrections) in the unified and coherent fashion. The damping of magnetic polaron state, which is quite different from the damping of the scattering states, finds a natural interpretation within the present self-consistent scheme.
EXACT NUMERICAL VALUES OF DIAGONAL MATRIX ELEMENTS nl, AS n≤8and-7≤k≤4, AND THE SYMMETRY OF APPELL'S FUNCTION F2(1, 1)
Authors: TARASOV V. F.
Published: December 2004

This article deals with the connection between diagonal matrix elements  for 3H- and DH-atoms and the property of Appell's function F2(1, 1) mirror-like symmetry with respect to the center j0=-1/2 under the substitution j↦-j-1, j∈ℤ. Exact numerical values for nl of a 3H-atom, as n≤8 and -7≤k≤4, in the form of regular rational fractions are first given, i.e. practically for all the D. I. Mendeleev table.
SYMMETRY PROPERTIES OF IMPURITIES IN METALLIC SINGLE-WALL CARBON NANOTUBES
Authors: McCANN EDWARD , FAL'KO VLADIMIR I.
Published: December 2004

We use the effective mass model to describe spinless electrons near the Fermi level in metallic, single-wall carbon nanotubes. Taking into account two nonequivalent valleys (K-points) produces a four component Dirac equation for massless fermions, with the role of spin assumed by pseudospin due to the relative amplitude of the wavefunction on the two nonequivalent sublattice atoms. We show that the position of a short-ranged impurity within the hexagonal graphite unit cell produces a particular 4×4 matrix structure of the corresponding effective Hamiltonian. The symmetry of this Hamiltonian with respect to pseudospin flip is related to degeneracy breaking and, for an armchair tube, symmetry with respect to mirror reflection in the nanotube axis is related to pseudospin mixing. In a nanotube of finite length, we predict a sinusoidal oscillation of energy level shift as a function of energy with a period determined by the position of the impurity along the tube axis.
Characterization of recombinant CYP2C11: a vitamin D 25-hydroxylase and 24-hydroxylase
Authors: Rahmaniyan Mehrdad , Patrick Kennerly , Bell Norman H.
Published: December 2004

Studies were performed to further characterize the male-specific hepatic recombinant microsomal vitamin D 25-hydroxlase CYP2C11, expressed in baculovirus-infected insect cells, and determine whether it is also a vitamin D 24-hydroxylase. 25- and 24-hydroxylase activities were compared with those of 10 other recombinant hepatic microsomal cytochrome P-450 enzymes expressed in baculovirus-infected insect cells. Each of them 25-hydroxylated vitamin D2, vitamin D3, 1α-hydroxyvitamin D2(1αOHD2), and 1α-hydroxyvitamin D3(1αOHD3). CYP2C11 had the greatest activity with these substrates, except vitamin D3, which had the same activity as four of the other enzymes. The descending order of 25-hydroxylation by CYP2C11 was 1αOHD3> 1αOHD2> vitamin D2> vitamin D3. Each of the recombinant cytochrome P-450 enzymes 24-hydroxylated 1αOHD2. CYP2C11 had the greatest activity. 24-Hydroxylation of 1αOHD3was very low, and there was none with vitamin D3. Only CYP2C11 24-hydroxylated vitamin D2. Structures of vitamin D metabolites, including 24-hydroxyvitamin D2, 1,24( S)-dihydroxyvitamin D2, and 1,24-dihydroxyvitamin D3, were confirmed by HPLC and gas chromatography retention times and characteristic mass spectrometric fragmentation patterns. In male rats, hypophysectomy significantly reduced body weight, liver weight, hepatic CYP2C11 mRNA expression, and 24- and 25-hydroxylation of 1αOHD2. Expression of CYP2J3 and CYP2R1 mRNA did not change. In male rat hepatocytes, CYP2C11 mRNA expression and 24- and 25-hydroxylation were significantly reduced after culture for 24 h compared with uncultured cells. Expression of CYP2J3 and CYP2R1 either increased or did not change. It is concluded that CYP2C11 is a male-specific hepatic microsomal vitamin D 25-hydroxylase that hydroxylates vitamin D2, vitamin D3, 1αOHD2, and 1αOHD3. CYP2C11 is also a vitamin D 24-hydroxylase.
Acquired obesity is associated with increased liver fat, intra-abdominal fat, and insulin resistance in young adult monozygotic twins
Authors: Pietiläinen Kirsi Hannele , Rissanen Aila , Kaprio Jaakko , Mäkimattila Sari , Häkkinen Anna-Maija , Westerbacka Jukka , Sutinen Jussi , Vehkavaara Satu , Yki-Järvinen Hannele
Published: December 2004

We determined whether acquired obesity is associated with increases in liver or intra-abdominal fat or impaired insulin sensitivity by studying monozygotic (MZ) twin pairs discordant and concordant for obesity. We studied nineteen 24- to 27-yr-old MZ twin pairs, with intrapair differences in body weight ranging from 0.1 to 24.7 kg [body mass index (BMI) range 20.0–33.9 kg/m2], identified from a population-based FinnTwin16 sample. Fat distribution was determined by magnetic resonance imaging, percent body fat by dual-energy X-ray absorptiometry, liver fat by proton spectroscopy, insulin sensitivity by measuring the fasting insulin concentration, and whole body insulin sensitivity by the euglycemic insulin clamp technique. Intrapair differences in BMI were significantly correlated with those in intra-abdominal fat ( r = 0.82, P < 0.001) and liver fat ( r = 0.57, P = 0.010). Intrapair differences in fasting insulin correlated with those in subcutaneous abdominal ( r = 0.60, P = 0.008), intra-abdominal ( r = 0.75, P = 0.0001) and liver ( r = 0.49, P = 0.048) fat. Intrapair differences in whole body insulin sensitivity correlated with those in subcutaneous abdominal ( r = −0.72, P = 0.001) and intra-abdominal ( r = −0.55, P = 0.015) but not liver ( r = −0.20, P = 0.20) fat. We conclude that acquired obesity is associated with increases in intra-abdominal and liver fat and insulin resistance, independent of genetic factors.
Targeted overexpression of G protein-coupled receptor kinase-2 in osteoblasts promotes bone loss
Authors: Wang Liming , Liu Shiguang , Quarles L. Darryl , Spurney Robert F.
Published: December 2004

To investigate the role of G protein-coupled receptor kinases (GRKs) in regulating bone formation in vivo, we overexpressed the potent G protein-coupled receptor (GPCR) regulator GRK2 in osteoblasts, using the osteocalcin gene-2 promoter to target expression to osteoblastic cells. Using the parathyroid hormone (PTH) receptor as a model system, we found that overexpression of GRK2 in osteoblasts attenuated PTH-induced cAMP generation by mouse calvaria ex vivo. This decrease in GPCR responsiveness was associated with a reduction in bone mineral density (BMD) in transgenic (TG) mice compared with non-TG littermate controls. The decrease in BMD was most prominent in trabecular-rich lumbar spine and was not observed in cortical bone of the femoral shaft. Quantitative computed tomography indicated that the loss of trabecular bone was due to a decrease in trabecular thickness, with little change in trabecular number. Histomorphometric analyses confirmed the decrease in trabecular bone volume and demonstrated reduced bone remodeling, as evidenced by a decrease in osteoblast numbers and osteoblast-mediated bone formation. Osteoclastic activity also appeared to be reduced because urinary excretion of the osteoclastic activity marker deoxypyridinoline was decreased in TG mice compared with control animals. Consistent with reduced coupling of osteoblast-mediated bone formation to osteoclastic bone resorption, mRNA levels of both osteoprotegrin and receptor activator of NF-κB ligand were altered in calvaria of TG mice in a pattern that would promote a low rate of bone remodeling. Taken together, these data suggest that enhancing GRK2 activity and consequently reducing GPCR activity in osteoblasts produces a low bone-turnover state that reduces bone mass.
Isoproterenol decreases leptin release from rat and human adipose tissue through posttranscriptional mechanisms
Authors: Ricci Matthew R. , Lee Mi-Jeong , Russell Colleen D. , Wang Yanxin , Sullivan Sean , Schneider Stephen H. , Brolin Robert E. , Fried Susan K.
Published: December 2004

In vivo and in vitro studies indicate that β-adrenergic receptor agonists decrease leptin release from fat cells in as little as 30 min. Our objective was to determine whether alterations in leptin biosynthesis or secretion were involved in the short-term adrenergic regulation of leptin in human and rat adipose tissue. Isoproterenol (Iso) decreased leptin release from incubated adipose tissue of both nonobese and obese subjects to similar extent (−28 vs. −21% after 3 h). Inhibition of protein synthesis with cycloheximide did not block the effect of Iso on leptin release from human adipose tissue, suggesting that the Iso effect is independent of leptin synthesis. Iso also tended to increase tissue leptin content at the end of the 3-h incubation, as expected from the observed inhibition of release. Consistent with a posttranslational mechanism, Iso treatment did not affect leptin mRNA levels or relative rate of leptin biosynthesis as directly assessed by [35S]methionine incorporation into immunoprecipitable leptin. In contrast to these results in human adipose tissues, Iso did not decrease basal leptin release from rat adipose tissue. However, Iso did decrease insulin-stimulated leptin release by inhibiting the ability of insulin to increase leptin biosynthesis without detectably affecting leptin mRNA levels. Thus, in both human and rat, adrenergic regulation of posttranscriptional events (secretion in humans, translation in rats) may contribute to the rapid decline in circulating leptin that occurs when the sympathetic nervous system is activated, such as during fasting and cold exposure. Furthermore, the rat does not provide an ideal model to study mechanisms of cellular leptin regulation in humans.
Fetal renal and blood pressure responses to steroid infusion after early prenatal treatment with dexamethasone
Authors: Moritz Karen M. , Jefferies Andrew , Wintour E. Marelyn , Dodic Miodrag
Published: December 2004

Maternal infusion of dexamethasone for 48 h early in gestation results in upregulation of mRNA for mineralocorticoid and glucocorticoid (MR and GR) receptors and angiotensin II receptors in ovine fetal kidneys late in gestation. This study sought to determine whether dexamethasone exposure results in changes in renal function and blood pressure responsiveness to infused cortisol or aldosterone in the late-gestation fetus. Merino ewes carrying single fetuses were infused with isotonic saline (Sal; n = 9) or dexamethasone (Dex, 0.48 mg/h; n = 10) for 48 h between days 26 and 28 of gestation (term = 150 days). At 115–122 days, renal function and blood pressure were measured in fetuses during a 4-h infusion of saline, cortisol (100 μg/h), or aldosterone (5 μg/h). Infusions were given in random order at least 2 days apart. Basal blood pressure and renal function were similar in Sal and Dex groups and did not change over the course of saline infusion. Cortisol infusion caused similar increases in blood pressure, urine flow, and glomerular filtration rate (GFR) in the groups. Aldosterone infusion caused a significantly different GFR response between the groups [ P(treatment × time) < 0.05], but increase in K excretion and decrease in Na-to-K ratio were similar in the groups. The similar results obtained with cortisol and aldosterone infusion suggest no increased renal functional maturity to those hormones after early prenatal dexamethasone exposure. This suggests that changes in mRNA for MR and GR in kidneys of dexamethasone-exposed fetuses do not result in functional differences and highlights the renin-angiotensin system, as reported previously, as more important in this model.
Lithium treatment inhibits renal GSK-3 activity and promotes cyclooxygenase 2-dependent polyuria
Authors: Rao Reena , Zhang Ming-Zhi , Zhao Min , Cai Hui , Harris Raymond C. , Breyer Matthew D. , Hao Chuan-Ming
Published: December 2004

The use of LiCl in clinical psychiatry is routinely complicated by overt nephrogenic diabetes insipidus (NDI), the mechanism of which is incompletely understood. In vitro studies indicate that lithium can induce renal medullary interstitial cell cyclooxygenase 2 (COX2) protein expression via inhibition of glycogen synthase kinase-3β (GSK-3β). Both COX1 and COX2 are expressed in the kidney. Renal prostaglandins have been suggested to play an important role in lithium-induced polyuria. The present studies examined whether induction of the COX2 isoform contributes to LiCl-induced polyuria. Four days after initiation of lithium treatment in C57 BL/6J mice, urine volume increased in LiCl-treated mice by fourfold compared with controls ( P < 0.0001) and was accompanied by decreased urine osmolality. This was temporally associated with increased renal COX2 protein expression and increased urinary PGE2 excretion, whereas COX1 levels remained unchanged. COX2 inhibition significantly blunted lithium-induced polyuria ( P < 0.0001) and reduced urinary PGE2 levels. Lithium-associated polyuria was also seen in COX1−/− mice and was associated with increased urinary PGE2. COX2 inhibition completely prevented polyuria and PGE2 excretion in COX1−/− mice, suggesting that COX2, but not COX1, plays a critical role in lithium-induced polyuria. Lithium also induced renal medullary COX2 protein expression in congenitally polyuric antidiuretic hormone (AHD)-deficient rats, demonstrating that lithium-induced COX2 protein expression is not secondary to altered ADH levels or polyuria. Lithium also decreased renal medullary GSK-3β activity, and this was temporally related to increased COX2 expression in the kidney from lithium-treated mice, consistent with a tonic in vivo suppression of COX2 expression by GSK-3 activity. In conclusion, these findings temporally link decreased GSK-3 activity to enhanced renal COX2 expression and COX2-derived urine PGE2 excretion. Suppression of COX2-derived PGE2 blunts lithium-associated polyuria.
Qualitative phase analysis system for crystalline mixtures based on X-ray powder diffraction file
Authors: Qiao YuanYuan , Xi YunFei , Zhuo DongTao , Wang Ji Jun , Lin ShaoFan
Published: December 2004

A qualitative phase identification system for crystalline mixtures is presented. The system provides up to five-phase qualitative identification using up to nine-peak filtration, and additive full peak matching based on the powder diffraction file of ICDD. It was implemented using Microsoft Visual C++, and runs under most common Windows systems. Screenshots and examples are included.
X-ray powder diffraction analysis and initial Rietveld characterization of SmAlSi and SmAlGe
Authors: Pikus S. , Olszewska E. , Mel’nyk I. , Gladyshevskii R. E.
Published: December 2004

The structures of SmAlSi and SmAlGe were determined by the powder diffraction method. These compounds have a tetragonal structure of LaPtSi type, which is a ternary substitutional variant of α-ThSi2. Both prototype structures have the same extinction rules, and as a result, the choice of the structural type must be based on very careful examination of the peak intensities. This was done with the aid of a Rietveld refinement, which indicates a better fit of the LaPtSi structure.
Solution of heavy atom structures from powder diffraction data using direct methods. A review of structures solved at Aarhus University
Authors: Christensen Axel Nørlund
Published: December 2004

Heavy atoms dominate the X-ray scattering from many inorganic compounds like oxides and oxalates, and often only partial structures of these compounds can be obtained by X-ray powder diffraction data. Combining information from X-ray and neutron diffraction data is an advantage. Scattering contributions from the atoms are more evenly distributed in neutron diffraction data than in X-ray diffraction data. Neutron diffraction data can then be used to complete a structure partially solved with data from an X-ray diffraction pattern. Examples of heavy atom structures solved in the time period 1983–2004 using direct methods outlined above are presented.
UACIEM: A new method to extract reliable intensities of nonequivalent systematical overlapping reflections from powder diffraction data
Authors: Ma H. W. , Liang J. K. , Liu G. Y. , Rao G. H.
Published: December 2004

A new method, namely UACIEM, to extract reliable intensities of nonequivalent systematical overlapping reflections has been proposed and tested by simulated powder diffraction data from known crystal structures. Using both crystallographic and structural chemistry information, the method reconstructs diffraction intensities and solves a crystal structure through an iterative procedure. Our study shows that UACIEM is successful for cases where more than 30% of the total scattering power is located with precision from equivalent systematical overlapping reflections. The UACIEM process is not needed when equivalent systematical overlapping reflections are sufficient to reveal a crystal structure. UACIEM may fail in cases when: (i) only a small portion of the total scattering power (e.g., less than 7%) can be located, and (ii) most of the total scattering power (e.g., 95%) is located, but the atomic coordinates are not accurately known. The UACIEM method is superior to the simple equipartition methods for nonequivalent systematical overlapping reflections.