bluuebunny/crossref_metadata_2025 huggingface dataset:
Perceptual coherence in listeners having longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing
Authors: Pittman Andrea
Published: January 2008

Perceptual coherence, the process by which the individual elements of complex sounds are bound together, was examined in adult listeners with longstanding childhood hearing losses, listeners with adult-onset hearing losses, and listeners with normal hearing. It was hypothesized that perceptual coherence would vary in strength between the groups due to their substantial differences in hearing history. Bisyllabic words produced by three talkers as well as comodulated three-tone complexes served as stimuli. In the first task, the second formant of each word was isolated and presented for recognition. In the second task, an isolated formant was paired with an intact word and listeners indicated whether or not the isolated second formant was a component of the intact word. In the third task, the middle component of the three-tone complex was presented in the same manner. For the speech stimuli, results indicate normal perceptual coherence in the listeners with adult-onset hearing loss but significantly weaker coherence in the listeners with childhood hearing losses. No differences were observed across groups for the nonspeech stimuli. These results suggest that perceptual coherence is relatively unaffected by hearing loss acquired during adulthood but appears to be impaired when hearing loss is present in early childhood.
On the reflection of coupled Rayleigh-like waves at surface defects in plates
Authors: Masserey Bernard , Fromme Paul
Published: January 2008

The reflection of coupled Rayleigh-like waves from surface defects in elastic plates is investigated experimentally and analyzed on the basis of an analytical model and finite difference simulations. The propagation of Rayleigh-like waves in plates is characterized by an energy transfer to the opposite plate side and back over a distance called the beat length. Experimental results clearly show this beating effect and its dependency on the frequency-thickness product, and excellent agreement is obtained with existing analytical predictions. The propagation and scattering are modeled separately for the fundamental A0 and S0 Lamb modes that constitute the incident Rayleigh-like wave. The reflection coefficients from surface slots are investigated using finite difference simulations and the reflected Rayleigh-like wave is obtained by superposition. The theoretical model reveals strong dependencies of the reflected field on the ratio between excitation distance and beat length and on the cutoff frequencies of specific higher Lamb modes. Standard pulse-echo measurements allow for the detection of small defects from a remote transducer location. Good agreement is obtained between the predicted and measured amplitude spectra of the reflected Rayleigh-like wave. The developed model allows for the evaluation of defect location and damaged plate side using a combination of time-of-flight and frequency measurements.
Comparison of magnetic resonance imaging-based vocal tract area functions obtained from the same speaker in 1994 and 2002
Authors: Story Brad H.
Published: January 2008

A new set of area functions for vowels has been obtained with magnetic resonance imaging from the same speaker as that previously reported in 1996 [Story et al., J. Acoust. Soc. Am. 100, 537–554 (1996)]. The new area functions were derived from image data collected in 2002, whereas the previously reported area functions were based on magnetic resonance images obtained in 1994. When compared, the new area function sets indicated a tendency toward a constricted pharyngeal region and expanded oral cavity relative to the previous set. Based on calculated formant frequencies and sensitivity functions, these morphological differences were shown to have the primary acoustic effect of systematically shifting the second formant (F2) downward in frequency. Multiple instances of target vocal tract shapes from a specific speaker provide additional sampling of the possible area functions that may be produced during speech production. This may be of benefit for understanding intraspeaker variability in vowel production and for further development of speech synthesizers and speech models that utilize area function information.
The effect of masker level uncertainty on intensity discrimination
Authors: Buss Emily
Published: January 2008

Thresholds were measured for detection of an increment in level of a 60-dB SPL target tone at 1kHz, either in quiet or in the presence of maskers at 0.5 and 2kHz. Interval-by-interval level rove applied independently to remote masker tones substantially elevated thresholds compared to intensity discrimination in quiet, an effect on the order of 10+dB [10log(ΔI∕I)]. Asynchronous onset and stimulus envelope mismatches across frequency reduced but did not eliminate masking. A preinterval cue to signal frequency had no effect, but cuing masker frequency reduced thresholds, whether or not masker level was also cued. About 1 to 2dB of threshold elevation in these conditions can be attributed to energetic masking. Decreasing the overall presentation level and increasing masker separation essentially eliminates energetic masking; under these conditions masker level rove elevates thresholds by approximately 7dB when the target and masker tones are gated synchronously. This masking persists even when the flanking masker tones are presented contralateral to the target. Results suggest that observers tend to listen synthetically, even in conditions when this strategy reduces sensitivity to the intensity increment.
Evaluation of the angular spectrum approach for simulations of near-field pressures
Authors: Zeng Xiaozheng , McGough Robert J.
Published: January 2008

The implementation of the angular spectrum approach based on the two-dimensional fast Fourier transform is evaluated for near-field pressure simulations of square ultrasound transducers, where the three-dimensional pressure field is calculated from the normal velocity distribution on the transducer surface. The pressure field is propagated in the spatial frequency domain with the spatial propagator or the spectral propagator. The spatial propagator yields accurate results in the central portion of the computational grid while significant errors are produced near the edge due to the finite extent of the window applied to the spatial propagator. Likewise, the spectral propagator is inherently undersampled in the spatial frequency domain, and this causes high frequency errors in the computed pressure field. This aliasing problem is alleviated with angular restriction. The results show that, in nonattenuating media, the spatial propagator achieves smaller errors than the spectral propagator after the region of interest is truncated to exclude the windowing error. For pressure calculations in attenuating media or with apodized pistons as sources, the spatial and spectral propagator achieve similar accuracies. In all simulations, the angular spectrum calculations with the spatial propagator take more time than calculations with the spectral propagator.
The effects of environmental and classroom noise on the academic attainments of primary school children
Authors: Shield Bridget M. , Dockrell Julie E.
Published: January 2008

While at school children are exposed to various types of noise including external, environmental noise and noise generated within the classroom. Previous research has shown that noise has detrimental effects upon children’s performance at school, including reduced memory, motivation, and reading ability. In England and Wales, children’s academic performance is assessed using standardized tests of literacy, mathematics, and science. A study has been conducted to examine the impact, if any, of chronic exposure to external and internal noise on the test results of children aged 7 and 11 in London (UK) primary schools. External noise was found to have a significant negative impact upon performance, the effect being greater for the older children. The analysis suggested that children are particularly affected by the noise of individual external events. Test scores were also affected by internal classroom noise, background levels being significantly related to test results. Negative relationships between performance and noise levels were maintained when the data were corrected for socio-economic factors relating to social deprivation, language, and special educational needs. Linear regression analysis has been used to estimate the maximum levels of external and internal noise which allow the schools surveyed to achieve required standards of literacy and numeracy.
Evidence for double acoustic windows in the dolphin, Tursiops truncatus
Authors: Popov Vladimir V. , Supin Alexander Ya. , Klishin Vladimir O. , Tarakanov Mikhail B. , Pletenko Mikhail G.
Published: January 2008

In a bottlenose dolphin positions of sound receiving areas on the head surface were determined by comparing the acoustic delays from different sound-source positions. For this investigation, auditory brainstem responses (ABRs) to short tone pips were recorded and their latencies were measured at different sound source positions. After correction for the latency dependence on response amplitude, the difference in ABR latencies was adopted as being the difference of the acoustic delays. These delay differences were used to calculate the position of the sound-receiving point. Measurements were conducted at sound frequencies from 16to128kHz, in half-octave steps. At probe frequencies of 16 and 22.5kHz, the receiving area was located 21.7–26cm caudal of the melon tip, which is near the bulla and auditory meatus. At higher probe frequencies, from 32to128kHz, the receiving area was located from 9.3to13.1cm caudal of the melon tip, which corresponds to a proximal part of the lower jaw. Thus, at least two sound-receiving areas (acoustic windows) with different frequency sensitivity were identified.
Approximations of inverse boundary element methods with partial measurements of the pressure field
Authors: Valdivia Nicolas P. , Williams Earl G. , Herdic Peter C.
Published: January 2008

Boundary element methods (BEMs) based near-field acoustic holography (NAH) requires the measurement of the pressure field over a closed surface in order to recover the normal velocity on a nearby conformal surface. There are practical cases when measurements are available over a patch from the measurement surface in which conventional inverse BEM based NAH (IBEM) cannot be applied directly, but instead as an approximation. In this work two main approximations based on the indirect-implicit methods are considered: Patch IBEM and IBEM with Cauchy data. Patch IBEM can be applied with a continuation procedure, which as its predecessor patch NAH (a well known technique that can be used on separable geometries of the wave equation) continues the pressure field using an iterative procedure, or it can be applied by a direct procedure. On the other hand, IBEM with Cauchy data requires measurements over two conformal patches and it will be shown that this technique will be reliable regardless of the position of the source. The theory behind each method will be justified and validated using a cylindrical surface with numerical data generated by point sources, and using experimental data from a cylindrical fuselage excited by a point force.
Comparative measurements of loudspeakers in a listening situation
Authors: Lavandier Mathieu , Herzog Philippe , Meunier Sabine
Published: January 2008

Comparison of loudspeakers is a major concern during design or product selection. There are several standards for the measurement of loudspeaker characteristics, but none of them provides hints for a rigorous comparison between devices. In this study, different ways of evaluating acoustical dissimilarity between loudspeakers were compared. Several methods of signal analysis were used, and for each method a metric evaluating the dissimilarity between two signals was defined. The correlation between the different dissimilarity evaluations over a significant panel of loudspeakers led to identified classes of measurements. A specific aspect of this work is that measurements were performed in a standard listening environment, rather than in an anechoic or reverberant one. It allowed the use of the recorded signals for a simple listening test, providing a perceptual metric which was compared to the acoustical ones. It also allowed the introduction of auditory models in the computation of some acoustical metrics, so defining a new class of measurements which gave results close to the perceptual ones.
On fiber optic probe hydrophone measurements in a cavitating liquid
Authors: Zijlstra Aaldert , Ohl Claus Dieter
Published: January 2008

The measurement of high-pressure signals is often hampered by cavitation activity. The usage of a fiber optic probe hydrophone possesses advantages over other hydrophones, yet when measuring in a cavitating liquid large variations in the signal amplitude are found; in particular when the pressure signal recovers back to positive values. With shadowgraphy the wave propagation and cavity dynamics are imaged and the important contributions of secondary shock waves emitted from collapsing cavitation bubbles are revealed. Interestingly, just adding a small amount of acidic acid reduces the cavitation activity to a large extent. With this treatment an altered primary pressure profile which does not force the cavitation bubbles close to fiber tip into collapse has been found. Thereby, the shot-to-shot variations are greatly reduced.
Predicting midsagittal pharyngeal dimensions from measures of anterior tongue position in Swedish vowels: Statistical considerations
Authors: Jackson Michel T.-T. , McGowan Richard S.
Published: January 2008

In a re-analysis of x rays of speakers producing Swedish vowels, midsagittal pharyngeal dimensions were predicted from anterior tongue positions using procedures based on estimated tongue pellet positions. Principal component analysis was used to reduce the number of pellet degrees of freedom from eight to three prior to applying linear regression from these three independent variables to dependent vocal tract midsagittal cross distances. Except for the regions around the laryngopharynx and uvula, the pharynx dimensions were predictable from linear regressions and were significant at the p<0.05 level. Numerical experiments show that it is crucial to reduce the number of independent variables in tests of statistical significance.
Longitudinal changes in speech recognition in older persons
Authors: Dubno Judy R. , Lee Fu-Shing , Matthews Lois J. , Ahlstrom Jayne B. , Horwitz Amy R. , Mills John H.
Published: January 2008

Recognition of isolated monosyllabic words in quiet and recognition of key words in low- and high-context sentences in babble were measured in a large sample of older persons enrolled in a longitudinal study of age-related hearing loss. Repeated measures were obtained yearly or every 2 to 3 years. To control for concurrent changes in pure-tone thresholds and speech levels, speech-recognition scores were adjusted using an importance-weighted speech-audibility metric (AI). Linear-regression slope estimated the rate of change in adjusted speech-recognition scores. Recognition of words in quiet declined significantly faster with age than predicted by declines in speech audibility. As subjects aged, observed scores deviated increasingly from AI-predicted scores, but this effect did not accelerate with age. Rate of decline in word recognition was significantly faster for females than males and for females with high serum progesterone levels, whereas noise history had no effect. Rate of decline did not accelerate with age but increased with degree of hearing loss, suggesting that with more severe injury to the auditory system, impairments to auditory function other than reduced audibility resulted in faster declines in word recognition as subjects aged. Recognition of key words in low- and high-context sentences in babble did not decline significantly with age.
Effects of level and background noise on interaural time difference discrimination for transposed stimuli
Authors: Dreyer Anna A. , Oxenham Andrew J.
Published: January 2008

Just-noticeable interaural time differences were measured for low-frequency pure tones, high-frequency sinusoidally amplitude-modulated (SAM) tones, and high-frequency transposed stimuli, at multiple levels with or without a spectrally notched diotic noise to prevent spread of excitation. Performance with transposed stimuli and pure tones was similar in quiet; however, in noise, performance was poorer for transposed stimuli than for pure tones. Performance with SAM tones was always poorest. In all conditions, performance improved slightly with increasing level. The results suggest that the equivalence postulated between transposed stimuli and pure tones is not valid in the presence of a spectrally notched background noise.
The Spatial Pattern and Mechanisms of Heat-Content Change in the North Atlantic
Authors: Lozier M. Susan , Leadbetter Susan , Williams Richard G. , Roussenov Vassil , Reed Mark S. C. , Moore Nathan J.
Published: January 2008

The total heat gained by the North Atlantic Ocean over the past 50 years is equivalent to a basinwide increase in the flux of heat across the ocean surface of 0.4 ± 0.05 watts per square meter. We show, however, that this basin has not warmed uniformly: Although the tropics and subtropics have warmed, the subpolar ocean has cooled. These regional differences require local surface heat flux changes (±4 watts per square meter) much larger than the basinwide average. Model investigations show that these regional differences can be explained by large-scale, decadal variability in wind and buoyancy forcing as measured by the North Atlantic Oscillation index. Whether the overall heat gain is due to anthropogenic warming is difficult to confirm because strong natural variability in this ocean basin is potentially masking such input at the present time.
Mutations in the Pericentrin (
PCNT
) Gene Cause Primordial Dwarfism
Authors: Rauch Anita , Thiel Christian T. , Schindler Detlev , Wick Ursula , Crow Yanick J. , Ekici Arif B. , van Essen Anthonie J. , Goecke Timm O. , Al-Gazali Lihadh , Chrzanowska Krystyna H. , Zweier Christiane , Brunner Han G. , Becker Kristin , Curry Cynthia J. , Dallapiccola Bruno , Devriendt Koenraad , Dörfler Arnd , Kinning Esther , Megarbane André , Meinecke Peter , Semple Robert K. , Spranger Stephanie , Toutain Annick , Trembath Richard C. , Voss Egbert , Wilson Louise , Hennekam Raoul , de Zegher Francis , Dörr Helmuth-Günther , Reis André
Published: January 2008

Fundamental processes influencing human growth can be revealed by studying extreme short stature. Using genetic linkage analysis, we find that biallelic loss-of-function mutations in the centrosomal pericentrin (
PCNT
) gene on chromosome 21q22.3 cause microcephalic osteodysplastic primordial dwarfism type II (MOPD II) in 25 patients. Adults with this rare inherited condition have an average height of 100 centimeters and a brain size comparable to that of a 3-month-old baby, but are of near-normal intelligence. Absence of PCNT results in disorganized mitotic spindles and missegregation of chromosomes. Mutations in related genes are known to cause primary microcephaly (
MCPH1, CDK5RAP2, ASPM
, and
CENPJ
).
Three-Dimensional Super-Resolution Imaging by Stochastic Optical Reconstruction Microscopy
Authors: Huang Bo , Wang Wenqin , Bates Mark , Zhuang Xiaowei
Published: January 2008

Recent advances in far-field fluorescence microscopy have led to substantial improvements in image resolution, achieving a near-molecular resolution of 20 to 30 nanometers in the two lateral dimensions. Three-dimensional (3D) nanoscale-resolution imaging, however, remains a challenge. We demonstrated 3D stochastic optical reconstruction microscopy (STORM) by using optical astigmatism to determine both axial and lateral positions of individual fluorophores with nanometer accuracy. Iterative, stochastic activation of photoswitchable probes enables high-precision 3D localization of each probe, and thus the construction of a 3D image, without scanning the sample. Using this approach, we achieved an image resolution of 20 to 30 nanometers in the lateral dimensions and 50 to 60 nanometers in the axial dimension. This development allowed us to resolve the 3D morphology of nanoscopic cellular structures.
Decreased Potency of the
Vibrio cholerae
Sheathed Flagellum To Trigger Host Innate Immunity
Authors: Yoon Sang Sun , Mekalanos John J.
Published: January 2008

Vibrio cholerae
is a monoflagellated gram-negative bacterium that causes the severe diarrheal disease cholera. In contrast to
Salmonella enterica
serovar Typhimurium infection, which is accompanied by both acute diarrhea and high-level inflammation,
V. cholerae
infection is largely noninflammatory in human hosts. Bacterial flagella are composed of flagellin, a highly conserved protein that is also a target of the innate immune response. Because the
V. cholerae
flagellum is covered by a sheath, we hypothesized that it might be less prone to activation of the innate immune response than nonsheathed flagella, such as those produced by
Salmonella
serovar Typhimurium. Indeed, compared with
Salmonella
serovar Typhimurium flagella,
V. cholerae
flagella demonstrated significantly reduced NF-κB activation in A549 human pulmonary epithelial cells. However,
V. cholerae
flagellin monomers, FlaD and FlaC, were almost equally potent with purified FliC, a monomer derived from
Salmonella
serovar Typhimurium flagella, in NF-κB activation. Heat- and acid-induced dissociation assays showed that
Salmonella
serovar Typhimurium flagella disassembled far more readily into monomeric flagellins than
V. cholerae
flagella, suggesting that the differential levels of NF-κB activation by
V. cholerae
and
Salmonella
serovar Typhimurium flagella are likely attributable to the difference in their flagellin shedding. Our results suggest that monomer dissociation of
V. cholerae
flagella is suppressed likely due to the presence of the sheath and that this unique structural feature of
V. cholerae
flagella may have evolved as a strategy to evade flagellin-triggered host innate immune responses in various host species.
Degradation of Complement 3 by Streptococcal Pyrogenic Exotoxin B Inhibits Complement Activation and Neutrophil Opsonophagocytosis
Authors: Kuo Chih-Feng , Lin Yee-Shin , Chuang Woei-Jer , Wu Jiunn-Jong , Tsao Nina
Published: January 2008

Streptococcal pyrogenic exotoxin B (SPE B), a cysteine protease, is an important virulence factor in group A streptococcus (GAS) infection. The inhibition of phagocytic activity by SPE B may help prevent bacteria from being ingested. In this study, we examined the mechanism SPE B uses to enable bacteria to resist opsonophagocytosis. Using an enzyme-linked immunosorbent assay, we found that SPE B-treated serum impaired the activation of the classical, the lectin, and the alternative complement pathways. In contrast, C192S, a SPE B mutant lacking protease activity, had no effect on complement activation. Further study showed that cleavage of serum C3 by SPE B, but not C192S, blocked zymosan-induced production of reactive oxygen species in neutrophils as a result of decreased deposition of C3 fragments on the zymosan surface. Reconstitution of C3 into SPE B-treated serum unblocked zymosan-mediated neutrophil activation dose dependently. SPE B-treated, but not C192S-treated, serum also impaired opsonization of C3 fragments on the surface of GAS strain A20. Moreover, the amount of C3 fragments on the A20 cell surface, a SPE B-producing strain, was less than that on its isogenic mutant strain, SW507, after opsonization with normal serum. A20 opsonized with SPE B-treated serum was more resistant to neutrophil killing than A20 opsonized with normal serum, and SPE B-mediated resistance was C3 dependent. These results suggest a novel SPE B mechanism, one which degrades serum C3 and enables GAS to resist complement damage and opsonophagocytosis.
A Chemokine-Degrading Extracellular Protease Made by Group AStreptococcusAlters Pathogenesis by Enhancing Evasion of the Innate Immune Response
Authors: Sumby Paul , Zhang Shizhen , Whitney Adeline R. , Falugi Fabiana , Grandi Guido , Graviss Edward A. , DeLeo Frank R. , Musser James M.
Published: January 2008

Circumvention of the host innate immune response is critical for bacterial pathogens to infect and cause disease. Here we demonstrate that the group AStreptococcus(GAS;Streptococcus pyogenes) protease SpyCEP (S. pyogenescell envelope protease) cleaves granulocyte chemotactic protein 2 (GCP-2) and growth-related oncogene alpha (GROα), two potent chemokines made abundantly in human tonsils. Cleavage of GCP-2 and GROα by SpyCEP abrogated their abilities to prime neutrophils for activation, detrimentally altering the innate immune response. SpyCEP expression is negatively regulated by the signal transduction system CovR/S. Purified recombinant CovR bound thespyCEPgene promoter region in vitro, indicating direct regulation. Immunoreactive SpyCEP protein was present in the culture supernatants ofcovR/Smutant GAS strains but not in supernatants from wild-type strains. However, wild-type GAS strains do express SpyCEP, where it is localized to the cell wall. Strain MGAS2221, an organism representative of the highly virulent and globally disseminated M1T1 GAS clone, differed significantly from its isogenicspyCEPmutant derivative strain in a mouse soft tissue infection model. Interestingly, and in contrast to previous studies, the isogenic mutant strain generated lesions of larger size than those formed following infection with the parent strain. The data indicate that SpyCEP contributes to GAS virulence in a strain- and disease-dependent manner.
Chemical Attenuation of
Plasmodium berghei
Sporozoites Induces Sterile Immunity in Mice
Authors: Purcell Lisa A. , Yanow Stephanie K. , Lee Moses , Spithill Terry W. , Rodriguez Ana
Published: January 2008

Radiation and genetic attenuation of
Plasmodium
sporozoites are two approaches for whole-organism vaccines that protect against malaria. We evaluated chemical attenuation of sporozoites as an alternative vaccine strategy. Sporozoites were treated with the DNA sequence-specific alkylating agent centanamycin, a compound that significantly affects blood stage parasitemia and transmission of murine malaria and also inhibits
Plasmodium falciparum
growth in vitro. Here we show that treatment of
Plasmodium berghei
sporozoites with centanamycin impaired parasite function both in vitro and in vivo. The infection of hepatocytes by sporozoites in vitro was significantly reduced, and treated parasites showed arrested liver stage development. Inoculation of mice with sporozoites that were treated in vitro with centanamycin failed to produce blood stage infections. Furthermore, BALB/c and C57BL/6 mice vaccinated with treated sporozoites were protected against subsequent challenge with wild-type sporozoites. Our findings demonstrate that chemically attenuated sporozoites could be a viable alternative for the production of an effective liver stage vaccine for malaria.
Epidemiological Characteristics of Methicillin-Resistant
Staphylococcus aureus
Isolates from Children with Eczematous Atopic Dermatitis Lesions
Authors: Chung Hee-Jung , Jeon Hong-Seon , Sung Heungsup , Kim Mi-Na , Hong Soo-Jong
Published: January 2008

In this study, we investigated the rate of colonization of skin of children with atopic dermatitis (AD) by methicillin-resistant
Staphylococcus aureus
(MRSA) and characterized the isolates. Active skin lesions in pediatric AD patients were cultured with Rodac Staph (Komed, Korea).
S. aureus
isolates were examined for drug susceptibilities, analyzed for the
eta
,
etb
,
tst
, and
pvl
genes, and typed using
agr
polymorphism, pulsed-field gel electrophoresis of SmaI-restricted chromosomal DNA, and staphylococcal cassette chromosome
mec
(SCC
mec
) typing. Eighty-seven (75.4%) of 115 patients had cultivable
S. aureus
isolates, 16 of which (18.3%) were MRSA. All MRSA isolates were susceptible to chloramphenicol, rifampin, cotrimoxazole, and ciprofloxacin. While methicillin-susceptible
S. aureus
(MSSA) isolates were composed of 23 isolates of singular types and nine clusters comprising 48 isolates, MRSA isolates were typed into three clones: eight isolates of pulsotype A-
agr
-
1
-SCC
mec
IV, five isolates of pulsotype B-
agr
-
3
-SCC
mec
IIb-
etb
positive, and three isolates of pulsotype C-
agr
-
3
-SCC
mec
IV. Three SCC
mec
IVA MRSA isolates were
tst
positive, but none were positive for the
pvl
or
eta
gene. Among 71 MSSA isolates, 7 isolates were
tst
positive, 6 of which were pulsotype F-
agr
-
3
, and 9 of 10
agr
-
4
isolates were
eta
positive. The average ages of patients carrying MSSA, SCC
mec
IVA MRSA, and SCC
mec
IIb MRSA were 7.7 ± 4.6, 3.1 ± 1.5, and 8.2 ± 3.1 years, respectively. Among the patients carrying MRSA, two patients had been treated with oral antimicrobials, and one had been admitted to the hospital 18 months previously. In conclusion, community-acquired MRSA isolates of a few clones colonized the skin of patients with AD without risk factors for the acquisition of hospital-acquired MRSA, which suggested that the skin of children with AD may represent a significant reservoir of MRSA colonization in the community.
Use of PCR-BasedMycobacterium tuberculosisGenotyping To Prioritize Tuberculosis Outbreak Control Activities
Authors: Ashworth Maegan , Horan Kathleen L. , Freeman Robert , Oren Eyal , Narita Masahiro , Cangelosi Gerard A.
Published: January 2008

Genotypic analysis ofMycobacterium tuberculosisisolates is increasingly applied in direct support of tuberculosis outbreak control activities. This is facilitated by PCR-based strain typing methods that enable the genotypic characterization of samples containing small numbers ofM. tuberculosiscells. By using DNA extracted directly from primary diagnostic cultures, PCR-based methods were applied to a tuberculosis outbreak investigation and to surveillance in King County, Washington. In the outbreak investigation, five epidemiologically linkedM. tuberculosisisolates had a unique pattern at mycobacterial interspersed repeating unit (MIRU) loci 10 and 23 when the pattern was compared to the patterns in a local MIRU locus database. In order to quickly identify new cases involving this strain (termed SBRI10), targeted genotyping at these two loci was performed with cultures from epidemiologically associated tuberculosis cases. Isolates with the characteristic genotypes at loci 10 and 23 were further analyzed by use of a 12-locus MIRU panel and by repetitive-unit-sequence-based PCR (rep-PCR). Between May 2004 and January 2005, 82 cases were screened, of which 14 were identified for further analysis and 13 were confirmed to be infected with SBRI10. Between September 2005 and August 2006, surveillance universal genotyping was performed by using the 12-locus MIRU panel with DNA from primary diagnostic enrichment cultures. A total of 161 samples were submitted for analysis, and 156 were successfully typed. Fifty-one cases formed 18 presumptive clusters by MIRU locus typing. Of these, 30 cases were confirmed to be members of 11 clusters by rep-PCR. Presumptive genotypic data were available rapidly, sometimes within 2 weeks of diagnosis. In this fashion, PCR-based genotyping provided data that can be used to prioritize disease control activities.
DiarrheagenicEscherichia coliandShigellaStrains Isolated from Children in a Hospital Case-Control Study in Hanoi, Vietnam
Authors: Hien Bui Thi Thu , Scheutz Flemming , Cam Phung Dac , Serichantalergs Oralak , Huong Tran Thu , Thu Tran Minh , Dalsgaard Anders
Published: January 2008

This case-control study detected and characterizedShigellaand diarrheagenicEscherichia coli(DEC) types among Vietnamese children less than 5 years old. In 249 children with diarrhea and 124 controls,Shigellaspp. was an important cause of diarrhea (P< 0.05). We used multiplex PCR and DNA probes to detect enteroinvasiveE. coli(EIEC), enteroaggregativeE. coli(EAggEC), enteropathogenicE. coli(EPEC), attaching and effacingE. coli(A/EEC), verocytotoxin-producingE. coli(VTEC), and enterotoxigenicE. coli(ETEC). The prevalences of DEC in the diarrhea and control groups were 25.7 and 10.5%, respectively. In 62 children with diarrhea, 64 DEC strains included 22 EAggEC (8.8%), 2 EIEC (0.8%), 23 A/EEC (9.2%), 7 EPEC (2.8%), and 10 ETEC strains (4.0%). Among controls, 13 DEC strains included 5 EAggEC strains (4.0%), 7 A/EEC strains (5.6%), and 1 EPEC strain. The characterization of DEC by serotypes, antimicrobial susceptibility patterns, virulence genes, and pulsed-field gel electrophoresis showed the occurrence of many different and highly heterogenic DEC subtypes, but common serotypes were found among ETEC, EIEC and EPEC, respectively. Serotyping was used to distinguish between A/EEC and EPEC. However, A/EEC, EPEC, and EAggEC were isolated at high frequency from both cases and controls. Further in-depth studies are needed to better understand important virulence factors of DEC, especially A/EEC, EPEC, and EAggEC.
Sputum Smear Microscopy: Evaluation of Impact of Training, Microscope Distribution, and Use of External Quality Assessment Guidelines for Resource-Poor Settings
Authors: Van Rie A. , Fitzgerald D. , Kabuya G. , Van Deun A. , Tabala M. , Jarret N. , Behets F. , Bahati E.
Published: January 2008

Sputum smear microscopy is the main and often only laboratory technique used for the diagnosis of tuberculosis in resource-poor countries, making quality assurance (QA) of smear microscopy an important activity. We evaluated the effects of a 5-day refresher training course for laboratory technicians and the distribution of new microscopes on the quality of smear microscopy in 13 primary health care laboratories in Kinshasa, Democratic Republic of Congo. The 2002 external QA guidelines for acid-fast bacillus smear microscopy were implemented, and blinded rechecking of the slides was performed before and 9 months after the training course and microscope distribution. We observed that the on-site checklist was highly time-consuming but could be tailored to capture frequent problems. Random blinded rechecking by the lot QA system method decreased the number of slides to be reviewed. Most laboratories needed further investigation for possible unacceptable performance, even according to the least-stringent interpretation. We conclude that the 2002 external QA guidelines are feasible for implementation in resource-poor settings, that the efficiency of external QA can be increased by selecting sample size parameters and interpretation criteria that take into account the local working conditions, and that greater attention should be paid to the provision of timely feedback and correction of the causes of substandard performance at poorly performing laboratories.
Diagnostic Accuracy of Class 1 Integron PCR Method in Detection of Antibiotic Resistance inSalmonellaIsolates from Swine Production Systems
Authors: Rao Sangeeta , Maddox Carol W. , Hoien-Dalen Patricia , Lanka Sara , Weigel Ronald M.
Published: January 2008

The diagnostic accuracy of an integron PCR method (Int-PCR) for detecting class 1 integrons (1,000, 1,200, and 1,600 bp) in the identification of antibiotic-resistantSalmonellastrains was evaluated using 730Salmonellaisolates from pen floor samples collected from four swine production systems in Illinois. Three integron groupings were detected: 1,000 bp only, 1,600 bp only, and both 1,000 and 1,200 bp. The presence of any of the three class 1 integron groupings was associated with four-drug resistance (streptomycin, spectinomycin, sulfisoxazole, and tetracycline [St Spc Su Tet]). In addition, the presence of both the 1,000- and 1,200-bp integrons added resistance to ampicillin (Amp) and chloramphenicol (Cm), and the 1,600-bp integron added resistance to gentamicin (Gen) and kanamycin (Kan). DNA sequencing of integrons confirmed the presence of the aminoglycoside adenyl transferase (aadA) gene, conferring St Spc resistance in the 1,000-bp integron; the β-lactamase gene, conferring Amp resistance in the 1,200-bp integron; and theaadAandaadBgenes, conferring St Spc Gen Kan resistance in the 1,600-bp integron. The 1,600-bp integron appears to have the 1,000-bp intergron as its core, with additional genetic material conferring additional antibiotic resistance. The diagnostic accuracy of Int-PCR in detecting resistance to individual antibiotics was limited by the presence of phenotypic resistance in isolates without integrons. However, Int-PCR had high diagnostic accuracy (sensitivity and specificity) in detecting multidrug resistance: 0.98 and 0.92, respectively, for St Spc Su Tet; 0.95 and 1.0 for Amp Cm St Spc Su Tet; and 1.0 and 0.99 for Gen Kan St Spc Su Tet. Thus, Int-PCR can be valuable in epidemiological surveys as a screening tool for the detection of multidrug-resistantSalmonellastrains.
Ureaplasma urealyticum
Meningitis in an Adult Patient
Authors: Geiβdörfer Walter , Sandner Günter , John Stefan , Gessner André , Schoerner Christoph , Schröppel Klaus
Published: January 2008

A 38-year-old patient developed meningitis after a complicated kidney transplantation and organ rejection.
Ureaplasma urealyticum
was identified as the etiological agent by molecular and microbiological analyses of the cerebrospinal fluid. The patient was successfully treated with doxycycline and chloramphenicol. This is the first report of
Ureaplasma urealyticum
meningitis in an adult.
Rapid Identification of Mycobacteria by Raman Spectroscopy
Authors: Buijtels P. C. A. M. , Willemse-Erix H. F. M. , Petit P. L. C. , Endtz H. P. , Puppels G. J. , Verbrugh H. A. , van Belkum A. , van Soolingen D. , Maquelin K.
Published: January 2008

A number of rapid identification methods have been developed to improve the accuracy for diagnosis of tuberculosis and to speed up the presumptive identification of
Mycobacterium
species. Most of these methods have been validated for a limited group of microorganisms only. Here, Raman spectroscopy was compared to 16S rRNA sequencing for the identification of
Mycobacterium tuberculosis
complex strains and the most frequently found strains of nontuberculous mycobacteria (NTM). A total of 63 strains, belonging to eight distinct species, were analyzed. The sensitivity of Raman spectroscopy for the identification of
Mycobacterium
species was 95.2%. All
M. tuberculosis
strains were correctly identified (7 of 7; 100%), as were 54 of 57 NTM strains (94%). The differentiation between
M. tuberculosis
and NTM was invariably correct for all strains. Moreover, the reproducibility of Raman spectroscopy was evaluated for killed mycobacteria (by heat and formalin) versus viable mycobacteria. The spectra of the heat-inactivated bacteria showed minimal differences compared to the spectra of viable mycobacteria. Therefore, the identification of mycobacteria appears possible without biosafety level 3 precautions. Raman spectroscopy provides a novel answer to the need for rapid species identification of cultured mycobacteria in a clinical diagnostic setting.
High Genetic Diversity among
Mycobacterium avium
subsp.
paratuberculosis
Strains from German Cattle Herds Shown by Combination of IS
900
Restriction Fragment Length Polymorphism Analysis and Mycobacterial Interspersed Repetitive Unit-Variable-Number Tandem-Repeat Typing
Authors: Möbius Petra , Luyven Gabriele , Hotzel Helmut , Köhler Heike
Published: January 2008

Mycobacterium avium
subsp.
paratuberculosis
is the etiologic agent of Johne's disease and is endemic to the national cattle herds of many countries. Because of the very low level of genetic heterogeneity of this organism, it is difficult to select a workable procedure for strain differentiation at a resolution sufficient to investigate epidemiological links between herds or different ruminant species and the suggested zoonotic potential of
M. avium
subsp.
paratuberculosis
for Crohn's disease. Analysis of restriction fragment length polymorphisms (RFLPs) based on the insertion element IS
900
(IS
900
RFLP) with four restriction enzymes and 10 markers of specific mycobacterial interspersed repetitive units (MIRUs) and variable-number tandem repeats (VNTRs) was applied to 71 bovine
M. avium
subsp.
paratuberculosis
isolates originating from 14 herds from different regions in Germany. Among these isolates, all of which belonged to the
M. avium
subsp.
paratuberculosis
type II group, 17 genotypes were detected by IS
900
RFLP and consisted of a combination of seven BstEII, eight PstI, nine PvuII, and four BamHI restriction patterns. Novel RFLP types were found. The diversity of the
M. avium
subsp.
paratuberculosis
isolates inside the herds was different depending on the frequency of animal purchase. The results of typing by IS
900
RFLP and MIRU-VNTR analyses were not associated. Fifteen MIRU-VNTR patterns were identified with a discriminatory index of 0.905. The most common BstEII-based IS
900
RFLP type, type C1 (72%), was subdivided into 14 types by MIRU-VNTR analysis. A combination of fingerprinting and PCR-based techniques resulted in 24
M. avium
subsp.
paratuberculosis
genotypes and achieved a discriminatory index of 0.997. By using only BstEII and PstI digestion together with typing by MIRU-VNTR analysis, a discriminatory index of 0.993 was achieved. This is high enough to support epidemiological studies on a national as well as a global scale.
Subcutaneous Phaeohyphomycosis Caused by
Wallemia sebi
in an Immunocompetent Host
Authors: Guarro Josep , Gugnani Harish C. , Sood Neelam , Batra Rashmi , Mayayo Emilio , Gené Josepa , Kakkar Shalini
Published: January 2008

We report a case of subcutaneous phaeohyphomycosis due to
Wallemia sebi
in a 43-year-old-female, the first case reported since 1950. The lesion presented as a nonhealing ulcer on the dorsum of the left foot. Diagnosis was based on histological demonstration of the fungus and its recovery in culture.
Rapid Differentiation of Influenza A Virus Subtypes and Genetic Screening for Virus Variants by High-Resolution Melting Analysis
Authors: Lin Jih-Hui , Tseng Ching-Ping , Chen Yen-Ju , Lin Chy-Yung , Chang Shy-Shin , Wu Ho-Sheng , Cheng Ju-Chien
Published: January 2008

We assessed the use of high-resolution melting (HRM) analysis for the rapid identification of influenza A virus subtypes and the detection of newly emerging virus variants. The viral matrix gene was amplified by LightCycler real-time reverse transcription-PCR (RT-PCR) in the presence of the LCGreen I fluorescent dye. Upon optimization of the assay conditions, all the major influenza A virus subtypes, including H1N1, H3N2, H5N1, H7N3, and H9N2, were amplifiable by this method and had a PCR product length of 179 bp. Real-time RT-PCR of in vitro-transcribed H3N2 RNA revealed a standard curve for quantification with a linear range (correlation coefficient = 0.9935) across at least 8 log units of RNA concentrations and a detection limit of 10
3
copies of viral RNA. We performed HRM analysis of the PCR products with the HR-1 instrument and used the melting profiles as molecular fingerprints for virus subtyping. The virus subtypes were identified from the high-resolution derivative plot obtained by heteroduplex formation between the PCR products of the viral isolates tested and those of the reference viral isolates. The melting profiles were consistent with minimal interassay variability. Hence, an HRM database and a working protocol were established for the identification of these five influenza A virus subtypes. When this protocol was used to test 21 clinical influenza A virus isolates, the results were comparable to those obtained by RT-PCR with hemagglutinin-specific primer sets. Sequence variants of the clinical isolates (
n
= 4) were also revealed by our HRM analytical scheme. This assay requires no multiplexing or hybridization probes and provides a new approach for influenza A virus subtyping and genetic screening of virus variants in a clinical virology laboratory.
Hepatocellular carcinoma associated with recreational anabolic steroid use: Figure 1
Authors: Gorayski P , Thompson C H , Subhash H S , Thomas A C
Published: January 2008

A 35-year-old male bodybuilder was found to have a hepatocellular carcinoma (HCC) arising in a pre-existing hepatic adenoma following recreational anabolic steroid use. Given the widespread use of recreational anabolic steroids, another potentially life-threatening complication is highlighted in addition to the more commonly recognised hepatic adenoma. Malignant transformation to HCC from a pre-existing hepatic adenoma confirmed by immunohistochemical study has previously not been reported in athletes taking anabolic steroids. Further studies using screening programmes to identify high-risk individuals are recommended.
THE ENTANGLED PHOTONS GENERATION SYSTEM USING WEAK LIGHT IN FIBER OPTIC AND TIMING-WALK OFF COMPENSATION
Authors: YUPAPIN PREECHA P. , KHUNNAM WANCHAI , SUCHAT SUEBTARKUL
Published: January 2008

We propose a new system for multi-entangled photons generation using an all fiber optic arrangement. The generation of the entangled states of two, four and eight entangled photons using an all fiber optic scheme is analyzed. The timing-walk off on the entangled state of two and four entangled photons suffering from the polarization in fiber optic is characterized. The compensation of such effects and the optimal entangled states of the entangled photons in fiber optic are analyzed and discussed.
Functional characterization of PCFT/HCP1 as the molecular entity of the carrier-mediated intestinal folate transport system in the rat model
Authors: Inoue Katsuhisa , Nakai Yasuhiro , Ueda Sayaka , Kamigaso Shunsuke , Ohta Kin-ya , Hatakeyama Mai , Hayashi Yayoi , Otagiri Masaki , Yuasa Hiroaki
Published: January 2008

Proton-coupled folate transporter/heme carrier protein 1 (PCFT/HCP1) has recently been identified as a transporter that mediates the translocation of folates across the cellular membrane by a proton-coupled mechanism and suggested to be the possible molecular entity of the carrier-mediated intestinal folate transport system. To further clarify its role in intestinal folate transport, we examined the functional characteristics of rat PCFT/HCP1 (rPCFT/HCP1) expressed in Xenopus laevis oocytes and compared with those of the carrier-mediated folate transport system in the rat small intestine evaluated by using the everted tissue sacs. rPCFT/HCP1 was demonstrated to transport folate and methotrexate more efficiently at lower acidic pH and, as evaluated at pH 5.5, with smaller Michaelis constant ( Km) for the former (2.4 μM) than for the latter (5.7 μM), indicating its characteristic as a proton-coupled folate transporter that favors folate than methotrexate as substrate. rPCFT/HCP1-mediated folate transport was found to be inhibited by several but limited anionic compounds, such as sulfobromophthalein and sulfasalazine. All these characteristics of rPCFT/HCP1 were in agreement with those of carrier-mediated intestinal folate transport system, of which the Kmvalues were 1.2 and 5.8 μM for folate and methotrexate, respectively, in the rat small intestine. Furthermore, the distribution profile of the folate transport system activity along the intestinal tract was in agreement with that of rPCFT/HCP1 mRNA. This study is the first to clone rPCFT/HCP1, and we successfully provided several lines of evidence that indicate its role as the molecular entity of the intestinal folate transport system.