bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors contributing to bone conduction: The outer ear
Authors: Stenfelt Stefan , Wild Timothy , Hato Naohito , Goode Richard L.
Published: January 2003

The ear canal sound pressure and the malleus umbo velocity with bone conduction (BC) stimulation were measured in nine ears from five cadaver heads in the frequency range 0.1 to 10 kHz. The measurements were conducted with both open and occluded ear canals, before and after resection of the lower jaw, in a canal with the cartilage and soft tissues removed, and with the tympanic membrane (TM) removed. The sound pressure was about 10 dB greater in an intact ear canal than when the cartilage part of the canal had been removed. The occlusion effect was close to 20 dB for the low frequencies in an intact ear canal; this effect diminished with sectioning of the canal. At higher frequencies, the resonance properties of the ear canal determined the effect of occluding the ear canal. Sectioning of the lower jaw did not significantly alter the sound pressure in the ear canal. The sound radiated from the TM into the ear canal was investigated in four temporal bone specimens; this sound is significantly lower than the sound pressure in an intact ear canal with BC stimulation. The malleus umbo velocity with air conduction stimulation was investigated in nine temporal bone specimens and compared with the umbo velocity obtained with BC stimulation in the cadaver heads. The results show that for a normal open ear canal, the sound pressure in the ear canal with BC stimulation is not significant for BC hearing. At threshold levels and for frequencies below 2 kHz, the sound in the ear canal caused by BC stimulation is about 10 dB lower than air conduction hearing thresholds; this difference increases at higher frequencies. However, with the ear canal occluded, BC hearing is dominated by the sound pressure in the outer ear canal for frequencies between 0.4 and 1.2 kHz.
Prediction of backscatter coefficient in trabecular bones using a numerical model of three-dimensional microstructure
Authors: Padilla Frédéric , Peyrin Françoise , Laugier Pascal
Published: January 2003

A model of ultrasonic backscattering for cancellous bone saturated by water is proposed. This model assumes that scattering is caused by the solid trabeculae and describes the cancellous bone as a weak scattering medium. The backscatter coefficient is related to the spatial Fourier transform of bone microarchitecture and to the density and compressibility fluctuations between the solid trabeculae and the saturating fluid. The computations of the model make use of three-dimensional numerical images of bone microarchitecture, obtained by tomographic reconstructions with a 10 μm spatial resolution. With this model, the predictions of the frequency dependence and of the magnitude of the backscatter coefficient are reasonably accurate. The theoretical predictions are compared to experimental data obtained on 19 specimens. An accuracy error of approximately 1 dB was found (difference between the averaged experimental values and theoretical predictions). One limit of the model may come from inaccurate values of trabecular bone characteristics needed for the computations (density and longitudinal velocity), which are yet to be precisely determined for human trabecular bone. However, the model is only slightly sensitive to variations of bone material properties. It was found that an accuracy error of 2.2 dB at maximum resulted from inaccurate a priori values of bone material properties. A computation of the elastic mean free path in the medium suggests that multiple scattering plays a minor role in the working frequency bandwidth (0.4–1.2 MHz). It follows from these results that a weak scattering medium model may be appropriate to describe scattering from trabecular bone.
Effects of disfluencies, predictability, and utterance position on word form variation in English conversation
Authors: Bell Alan , Jurafsky Daniel , Fosler-Lussier Eric , Girand Cynthia , Gregory Michelle , Gildea Daniel
Published: January 2003

Function words, especially frequently occurring ones such as (the, that, and, and of ), vary widely in pronunciation. Understanding this variation is essential both for cognitive modeling of lexical production and for computer speech recognition and synthesis. This study investigates which factors affect the forms of function words, especially whether they have a fuller pronunciation (e.g., ði, ðæt, ænd, ʌv) or a more reduced or lenited pronunciation (e.g., ðə, ðīt, n, ə). It is based on over 8000 occurrences of the ten most frequent English function words in a 4-h sample from conversations from the Switchboard corpus. Ordinary linear and logistic regression models were used to examine variation in the length of the words, in the form of their vowel (basic, full, or reduced), and whether final obstruents were present or not. For all these measures, after controlling for segmental context, rate of speech, and other important factors, there are strong independent effects that made high-frequency monosyllabic function words more likely to be longer or have a fuller form (1) when neighboring disfluencies (such as filled pauses uh and um) indicate that the speaker was encountering problems in planning the utterance; (2) when the word is unexpected, i.e., less predictable in context; (3) when the word is either utterance initial or utterance final. Looking at the phenomenon in a different way, frequent function words are more likely to be shorter and to have less-full forms in fluent speech, in predictable positions or multiword collocations, and utterance internally. Also considered are other factors such as sex (women are more likely to use fuller forms, even after controlling for rate of speech, for example), and some of the differences among the ten function words in their response to the factors.
Low frequency coupled mode sound propagation over a continental shelf
Authors: Knobles D. P. , Stotts S. A. , Koch R. A.
Published: January 2003

A two-way integral equation coupled mode method is applied to a continental shelf ocean waveguide proposed for a special session devoted to range-dependent acoustic modeling at the 141st meeting of the Acoustical Society of America. The coupled mode solution includes both sediment trapped and continuum modes. The continuum is approximated by a finite number of leaky modes but neglects the branch cut contribution. Mode coupling matrix elements and the range evolution of the modal amplitudes show the nature of the mode coupling. Transmission loss versus range at 100 Hz predicted by the integral equation approach is compared to the transmission loss predicted by a wide angle parabolic equation method. While there is very good agreement, one observes small differences that can be interpreted as backscattering predicted by the integral equation solution.
Radial vibrations of orthotropic laminated hollow spheres
Authors: Stavsky Yehuda , Greenberg J. Barry
Published: January 2003

The three-dimensional elasticity problem of the radial vibrations of a composite hollow spherical shell laminated of spherically orthotropic layers is considered. After formulating the equations, the exact determinantal equation from which the frequencies of vibration can be extracted is developed. Some calculated results for combinations of isotropic and orthotropic materials indicate the sensitivity of the frequencies to the geometry and material make up of the shells.
Acoustic ray chaos and billiard system in Hamiltonian formalism (L)
Authors: Kawabe Tetsuji , Aono Keisuke , Shin-ya Masakazu
Published: January 2003

The acoustic ray model with a strong connection to the billiard problem is presented within the framework of the Hamiltonian form. Introducing the background function into the sound-speed profile to confine all rays in a closed space, we obtain the ray trajectories consistent with a billiard picture. The ray chaos is observed when the perturbation due to inhomogeneity of the medium is taken into account. Based on the Poincaré surface of section and the Lyapunov exponents, we confirm that the chaos is characterized by almost the same structure as one observed in many Hamiltonian systems with two degrees of freedom.
Perception of the low pitch of frequency-shifted complexes
Authors: Moore Geoffrey A. , Moore Brian C. J.
Published: January 2003

When all of the components in a harmonic complex tone are shifted in frequency by Δf, the pitch of the complex shifts roughly in proportion to Δf. For tones with a small number of components, the shift is usually somewhat larger than predicted from pitch theories, which has been attributed to the influence of combination tones [Smoorenburg, J. Acoust. Soc. Am. 48, 924–941 (1970)]. Experiment 1 assessed whether combination tones influence the pitch of complex tones with more than five harmonics, by using noise to mask the combination tones. The matching stimulus was a harmonic complex. Test complexes were bandpass filtered with passbands centered on harmonic numbers 5 (resolved), 11 (intermediate), or 16 (unresolved) and fundamental frequencies (F0s) were 100, 200, or 400 Hz. For the intermediate and unresolved conditions, the matching stimuli were filtered with the same passband to minimize differences in the excitation patterns of the test and matching stimuli. For the resolved condition, the matching stimulus had a passband centered above that of the test stimulus, to avoid common partials. For resolved and intermediate conditions, pitch shifts were observed that could generally be predicted from the frequencies of the partials. The shifts were unaffected by addition of noise to mask combination tones. For the unresolved condition, no pitch shift was observed, which suggests that pitch is not based on temporal fine structure for stimuli containing only high unresolved harmonics. Experiment 2 used three-component complexes resembling those of Schouten [J. Acoust. Soc. Am. 34, 1418–1424 (1962)]. Nominal harmonic numbers were 3, 4, 5 (resolved), 8, 9, 10 (intermediate), or 13, 14, 15 (unresolved) and F0s were 50, 100, 200, or 400 Hz. Clear shifts in the matches were found for all conditions, including unresolved. For the latter, subjects may have matched the “center of gravity” of the excitation patterns of the test and matching stimuli.
The effect of superior auditory skills on vocal accuracy
Authors: Amir Ofer , Amir Noam , Kishon-Rabin Liat
Published: January 2003

The relationship between auditory perception and vocal production has been typically investigated by evaluating the effect of either altered or degraded auditory feedback on speech production in either normal hearing or hearing-impaired individuals. Our goal in the present study was to examine this relationship in individuals with superior auditory abilities. Thirteen professional musicians and thirteen nonmusicians, with no vocal or singing training, participated in this study. For vocal production accuracy, subjects were presented with three tones. They were asked to reproduce the pitch using the vowel /a/. This procedure was repeated three times. The fundamental frequency of each production was measured using an autocorrelation pitch detection algorithm designed for this study. The musicians’ superior auditory abilities (compared to the nonmusicians) were established in a frequency discrimination task reported elsewhere. Results indicate that (a) musicians had better vocal production accuracy than nonmusicians (production errors of 1/2 a semitone compared to 1.3 semitones, respectively); (b) frequency discrimination thresholds explain 43% of the variance of the production data, and (c) all subjects with superior frequency discrimination thresholds showed accurate vocal production; the reverse relationship, however, does not hold true. In this study we provide empirical evidence to the importance of auditory feedback on vocal production in listeners with superior auditory skills.
Evaluation of the risk of noise-induced hearing loss among unscreened male industrial workers
Authors: Prince Mary M. , Gilbert Stephen J. , Smith Randall J. , Stayner Leslie T.
Published: January 2003

Variability in background risk and distribution of various risk factors for hearing loss may explain some of the diversity in excess risk of noise-induced hearing loss (NIHL). This paper examines the impact of various risk factors on excess risk estimates of NIHL using data from the 1968–1972 NIOSH Occupational Noise and Hearing Survey (ONHS). Previous analyses of a subset of these data focused on 1172 highly “screened” workers. In the current analysis, an additional 894 white males (609 noise-exposed and 285 controls), who were excluded for various reasons (i.e., nonoccupational noise exposure, otologic or medical conditions affecting hearing, prior occupational noise exposure) have been added (n=2066) to assess excess risk of noise-induced material impairment in an unscreened population. Data are analyzed by age, duration of exposure, and sound level (8-h TWA) for four different definitions of noise-induced hearing impairment, defined as the binaural pure-tone average (PTA) hearing threshold level greater than 25 dB for the following frequencies: (a) 1–4 kHz (PTA1234), (b) 1–3 kHz (PTA123), (c) 0.5, 1, and 2 kHz (PTA512), and (d) 3, 4, and 6 kHz (PTA346). Results indicate that populations with higher background risks of hearing loss may show lower excess risks attributable to noise relative to highly screened populations. Estimates of lifetime excess risk of hearing impairment were found to be significantly different between screened and unscreened population for noise levels greater than 90 dBA. Predicted age-related risk of material hearing impairment in the ONHS unscreened population was similar to that predicted from Annex B and C of ANSI S3.44 for ages less than 60 years. Results underscore the importance of understanding differential risk patterns for hearing loss and the use of appropriate reference (control) populations when evaluating risk of noise-induced hearing impairment among contemporary industrial populations.
The effects of short-term training for spectrally mismatched noise-band speech
Authors: Fu Qian-Jie , Galvin John J.
Published: January 2003

The present study examined the effects of short-term perceptual training on normal-hearing listeners’ ability to adapt to spectrally altered speech patterns. Using noise-band vocoder processing, acoustic information was spectrally distorted by shifting speech information from one frequency region to another. Six subjects were tested with spectrally shifted sentences after five days of practice with upwardly shifted training sentences. Training with upwardly shifted sentences significantly improved recognition of upwardly shifted speech; recognition of downwardly shifted speech was nearly unchanged. Three subjects were later trained with downwardly shifted speech. Results showed that the mean improvement was comparable to that observed with the upwardly shifted training. In this retrain and retest condition, performance was largely unchanged for upwardly shifted sentence recognition, suggesting that these listeners had retained some of the improved speech perception resulting from the previous training. The results suggest that listeners are able to partially adapt to a spectral shift in acoustic speech patterns over the short-term, given sufficient training. However, the improvement was localized to where the spectral shift was trained, as no change in performance was observed for spectrally altered speech outside of the trained regions.
Measurement of surface wave transmission coefficient across surface-breaking cracks and notches in concrete
Authors: Song Won-Joon , Popovics John S. , Aldrin John C. , Shah Surendra P.
Published: January 2003

In this paper, a technique for measuring a surface wave transmission coefficient across surface-breaking cracks and notches in a heterogeneous but globally isotropic material (concrete) is presented. Once the transmission coefficient across a surface discontinuity is known, its depth may be estimated. There are many difficulties in measuring the transmission coefficient experimentally owing to effects of wave path dependence, unknown characteristics of the receiver and the wave source, and the variation of impact event or receiver coupling. To eliminate the undesired effects, a self-calibrating measurement scheme is applied to obtain the surface wave transmission coefficient across notches and surface-breaking cracks in concrete. The obtained signal transmission coefficient is not affected by the experimental setup or the heterogeneous nature of the material. The testing scheme is described and experimental results obtained from concrete specimens with notches and surface-breaking cracks are presented. Repeatable and reliable measurements of surface wave transmission coefficient are obtained, which demonstrate a strong relation to normalized discontinuity depth. A numerical study using the boundary element method is presented, which verifies the experimental findings.
Reduced models for the medium-frequency dynamics of stochastic systems
Authors: Ghanem Roger , Sarkar Abhijit
Published: January 2003

In this paper, a frequency domain vibration analysis procedure of a randomly parametered structural system is described for the medium-frequency range. In this frequency range, both traditional modal analysis and statistical energy analysis (SEA) procedures well-suited for low- and high-frequency vibration analysis respectively, lead to computational and conceptual difficulties. The uncertainty in the structural system can be attributed to various reasons such as the coupling of the primary structure with a variety of secondary systems for which conventional modeling is not practical. The methodology presented in the paper consists of coupling probabilistic reduction methods with dynamical reduction methods. In particular, the Karhunen–Loeve and Polynomial Chaos decompositions of stochastic processes are coupled with an operator decomposition scheme based on the spectrum of an energy operator adapted to the frequency band of interest.
Passive acoustic monitoring of human physiology during activity indicates health and performance of soldiers and firefighters
Authors: Scanlon Michael V.
Published: January 2003

The Army Research Laboratory has developed a unique gel-coupled acoustic physiological monitoring sensor that has acoustic impedance properties similar to the skin. This facilitates the transmission of body sounds into the sensor pad, yet significantly repels ambient airborne noises due to an impedance mismatch. The sensor’s sensitivity and bandwidth produce excellent signatures for detection and spectral analysis of diverse physiological events. Acoustic signal processing detects heartbeats, breaths, wheezes, coughs, blood pressure, activity, motion, and voice for communication and automatic speech recognition. The health and performance of soldiers, firefighters, and other first responders in strenuous and hazardous environments can be continuously and remotely monitored with body-worn acoustic sensors. Comfortable acoustic sensors can be in a helmet or in a strap around the neck, chest, and wrist. Noise-canceling sensor arrays help remove out-of-phase motion noise and enhance covariant physiology by using two acoustic sensors on the front sides of the neck and two additional acoustic sensors on each wrist. Pulse wave transit time between neck and wrist acoustic sensors will indicate systolic blood pressure. Larger torso-sized arrays can be used to acoustically inspect the lungs and heart, or built into beds for sleep monitoring. Acoustics is an excellent input for sensor fusion.
High resolution beamforming for small aperture arrays
Authors: Clark Chris , Null Tom , Wagstaff Ronald A.
Published: January 2003

Achieving fine resolution bearing estimates for multiple sources using acoustic arrays with small apertures, in number of wavelengths, is a difficult challenge. It requires both large signal-to-noise ratio (SNR) gains and very narrow beam responses. High resolution beamforming for small aperture arrays is accomplished by exploiting acoustical fluctuations. Acoustical fluctuations in the atmosphere are caused by wind turbulence along the propagation path, air turbulence at the sensor, source/receiver motion, unsteady source level, and fine scale temperature variations. Similar environmental and source dependent phenomena cause fluctuations in other propagation media, e.g., undersea, optics, infrared. Amplitude fluctuations are exploited to deconvolve the beam response functions from the beamformed data of small arrays to achieve high spatial resolution, i.e., fine bearing resolution, and substantial SNR gain. Results are presented for a six microphone low-frequency array with an aperture of less than three wavelengths. [Work supported by U.S. Army Armament Research Development and Engineering Center.]
Computerized analysis of bowel sounds in normal and small bowel obstructed rats
Authors: Sandler Richard , Mansy Hansen , Uhing Michael , Meyer Peter , Kimura Robert
Published: January 2003

Small bowel obstruction (SBO) is a common surgical emergency which may be mimicked by ileus or other nonsurgical conditions. The aims of this work is to delineate gastrointestinal sound (GIS) correlates in a rat model. Seven rats were studied in paired SBO and control states. Computerized analysis of GIS was performed under continuous IV sedation. After adaptive filtering, every GIS event was isolated and analyzed for duration and dominant frequency. It was found that long duration sounds (greater than 100 ms) occurred in each of the obstructed, but in none of the nonobstructed cases (p=0.02). The overall mean event duration and dominant frequency in SBO compared to control states was both significantly longer and lower (22.42.6 vs 7.0±2.6 ms, p=0.001 for duration; and 296±34 vs 427±33, p=0.001 for frequency). Besides these mean differences, there was also a clear evolution with time in GIS characteristics, with lengthening of the duration (+0.56 ms/min, p=0.001) and lowering of the dominant frequency (−3.3 Hz/min, p=0.01). It is concluded that GIS analysis may prove useful in the noninvasive, rapid, and accurate diagnosis of SBO.
Dissecting Apicoplast Targeting in the Malaria Parasite
Plasmodium falciparum
Authors: Foth Bernardo J. , Ralph Stuart A. , Tonkin Christopher J. , Struck Nicole S. , Fraunholz Martin , Roos David S. , Cowman Alan F. , McFadden Geoffrey I.
Published: January 2003

Transit peptides mediate protein targeting into plastids and are only poorly understood. We extracted amino acid features from transit peptides that target proteins to the relict plastid (apicoplast) of malaria parasites. Based on these amino acid characteristics, we identified 466 putative apicoplast proteins in the
Plasmodium falciparum
genome. Altering the specific charge characteristics in a model transit peptide by site-directed mutagenesis severely disrupted organellar targeting in vivo. Similarly, putative Hsp70 (DnaK) binding sites present in the transit peptide proved to be important for correct targeting.
Prevention of Transthyretin Amyloid Disease by Changing Protein Misfolding Energetics
Authors: Hammarström Per , Wiseman R. Luke , Powers Evan T. , Kelly Jeffery W.
Published: January 2003

Genetic evidence suggests that inhibition of amyloid fibril formation by small molecules should be effective against amyloid diseases. Known amyloid inhibitors appear to function by shifting the aggregation equilibrium away from the amyloid state. Here, we describe a series of transthyretin amyloidosis inhibitors that functioned by increasing the kinetic barrier associated with misfolding, preventing amyloidogenesis by stabilizing the native state. The trans-suppressor mutation, threonine 119 → methionine 119, which is known to ameliorate familial amyloid disease, also functioned through kinetic stabilization, implying that this small-molecule strategy should be effective in treating amyloid diseases.
PDGFRA
Activating Mutations in Gastrointestinal Stromal Tumors
Authors: Heinrich Michael C. , Corless Christopher L. , Duensing Anette , McGreevey Laura , Chen Chang-Jie , Joseph Nora , Singer Samuel , Griffith Diana J. , Haley Andrea , Town Ajia , Demetri George D. , Fletcher Christopher D. M. , Fletcher Jonathan A.
Published: January 2003

Most gastrointestinal stromal tumors (GISTs) have activating mutations in the KIT receptor tyrosine kinase, and most patients with GISTs respond well to Gleevec, which inhibits KIT kinase activity. Here we show that ∼35% (14 of 40) of GISTs lacking
KIT
mutations have intragenic activation mutations in the related receptor tyrosine kinase, platelet-derived growth factor receptor α (
PDGFRA
). Tumors expressing KIT or PDGFRA oncoproteins were indistinguishable with respect to activation of downstream signaling intermediates and cytogenetic changes associated with tumor progression. Thus,
KIT
and
PDGFRA
mutations appear to be alternative and mutually exclusive oncogenic mechanisms in GISTs.
Nitriding Iron at Lower Temperatures
Authors: Tong W. P. , Tao N. R. , Wang Z. B. , Lu J. , Lu K.
Published: January 2003

The microstructure in the surface layer of a pure iron plate was refined at the nanometer scale by means of a surface mechanical attrition treatment that generates repetitive severe plastic deformation of the surface layer. The subsequent nitriding kinetics of the treated iron with the nanostructured surface layer were greatly enhanced, so that the nitriding temperature could be as low as 300°C, which is much lower than conventional nitriding temperatures (above 500°C). This enhanced processing method demonstrates the technological significance of nanomaterials in improving traditional processing techniques and provides a new approach for selective surface reactions in solids.
Yes, Things Really Are Going Faster
Authors: Turner Michael S.
Published: January 2003

The Extravagant Universe
. Exploding Stars, Dark Energy, and the Accelerating Cosmos. Robert P. Kirshner. Princeton University Press, Princeton, NJ, 2002. 296 pp. $29.95, £19.95. ISBN 0-691-05862-8.

Writing for a popular audience, Kirshner presents a lively, personal, and often humorous account of the work that led him and his colleagues to conclude that under the influence of dark energy the universe is expanding at an accelerating rate.
In utero gene transfer of human factor IX to fetal mice can induce postnatal tolerance of the exogenous clotting factor
Authors: Waddington Simon N. , Buckley Suzanne M. K. , Nivsarkar Megha , Jezzard Sarah , Schneider Holm , Dahse Thomas , Kemball-Cook Geoff , Miah Maznu , Tucker Nick , Dallman Margaret J. , Themis Mike , Coutelle Charles
Published: January 2003

The fundamental hypotheses behind fetal gene therapy are that it may be possible (1) to achieve immune tolerance of transgene product and, perhaps, vector; (2) to target cells and tissues that are inaccessible in adult life; (3) to transduce a high percentage of rapidly proliferating cells, and in particular stem cells, with relatively low absolute virus doses leading to clonal transgene amplification by integrating vectors; and (4) to prevent early disease manifestation of genetic diseases. This study provides evidence vindicating the first hypothesis; namely, that intravascular prenatal administration of an adenoviral vector carrying the human factor IX (hFIX) transgene can induce immune tolerance of the transgenic protein. Following repeated hFIX protein injection into adult mice, after prenatal vector injection, we found persistence of blood hFIX and absence of hFIX antibodies in 5 of 9 mice. Furthermore, there was substantial hFIX expression after each of 2 reinjections of vector without detection of hFIX antibodies. In contrast, all adult mice that had not been treated prenatally showed a rapid loss of the injected hFIX and the development of high hFIX antibody levels, both clear manifestations of a strong immune reaction.
Pulmonary hypertension in sickle cell disease: cardiac catheterization results and survival
Authors: Castro Oswaldo , Hoque Mohammed , Brown Bernice D.
Published: January 2003

Few results on cardiac catheterization have been published for patients with sickle cell disease (SCD) with pulmonary hypertension (PHTN). Their survival once this complication develops is unknown. We analyzed hemodynamic data in 34 adult patients with SCD at right-sided cardiac catheterization and determined the relationship of PHTN to patient survival. In 20 patients with PHTN the average systolic, diastolic, and mean pulmonary artery pressures were 54.3, 25.2, and 36.0 mm Hg, respectively. For 14 patients with SCD without PHTN these values were 30.3, 11.7, and 17.8 mm Hg, respectively. The mean pulmonary capillary wedge pressure in patients with PHTN was higher than that in patients without PHTN (16.0 versus 10.6 mm Hg;P = .0091) even though echocardiography showed normal left ventricular systolic function. Cardiac output was high (8.6 L/min) for both groups of patients. The median postcatheterization follow-up was 23 months for patients with PHTN and 45 months for those without PHTN. Eleven patients (55%) with PHTN died compared to 3 (21%) patients without PHTN (χ2 = 3.83;P = .0503). The mean pulmonary artery pressure had a significant inverse relationship with survival (Cox proportional hazards modeling). Each increase of 10 mm Hg in mean pulmonary artery pressure was associated with a 1.7-fold increase in the rate (hazards ratio) of death (95% CI = 1.1-2.7; P = .028). The median survival for patients with PHTN was 25.6 months, whereas for patients without PHTN the survival was still over 70% at the end of the 119-month observation period (P = .044, Breslow-Gehan log-rank test). Our findings suggest that PHTN in patients with SCD shortened their survival.
Dendritic cell precursor populations of mouse blood: identification of the murine homologues of human blood plasmacytoid pre-DC2 and CD11c+ DC1 precursors
Authors: O'Keeffe Meredith , Hochrein Hubertus , Vremec David , Scott Bernadette , Hertzog Paul , Tatarczuch Lilliana , Shortman Ken
Published: January 2003

Immature and predendritic cells (pre-DCs) of human blood are the most readily accessible human DC sources available for study ex vivo. Murine homologues of human blood DCs have not been described. We report the isolation and characterization of 2 populations of precursor DCs in mouse blood. Mouse blood cells with the surface phenotype CD11cloCD11b−CD45RAhi closely resemble human plasmacytoid cells (or pre-DC2) by morphology and function. On stimulation with oligonucleotides containing CpG motifs (CpG), these cells make large amounts of type 1 interferons and rapidly develop into DCs that bear CD8, though they may be distinct from the CD8+ DCs in the unstimulated mouse. A second population of cells with the surface phenotype CD11c+CD11b+CD45RA− closely resembles the immediate precursors of pre-DC1, rapidly transforming into CD8− DCs after tumor necrosis factor-α (TNF-α) stimulation. These findings indicate the close relationship between human and mouse DCs, provided cells are obtained directly from equivalent source materials.
Tetramer-assisted identification and characterization of epitopes recognized by HLA A*2402–restricted Epstein-Barr virus–specific CD8+ T cells
Authors: Kuzushima Kiyotaka , Hayashi Naomi , Kudoh Ayumi , Akatsuka Yoshiki , Tsujimura Kunio , Morishima Yasuo , Tsurumi Tatsuya
Published: January 2003

We determined cytotoxic T lymphocyte (CTL) epitopes through screening with a computer-assisted algorithm and an enzyme-linked immunospot (ELISPOT) assay using in vitro–reactivated polyclonal Epstein-Barr virus (EBV)–specific CD8+ T cells as responders. In addition, to confirm that the epitopes were generated after endogenous processing and presentation of the EBV proteins, a novel T-cell receptor (TCR) down-regulation assay was introduced, in which a fluorescent tetrameric major histocompatibility complex (MHC)/peptide complex was employed for detecting TCR down-regulation after stimulation with the epitope presented on antigen-presenting cells. Through such screening, 3 HLA A*2402–restricted epitopes were identified: IYVLVMLVL, TYPVLEEMF, and DYNFVKQLF, derived from LMP2, BRLF1, and BMLF1 proteins, respectively. TCR down-regulation assays disclosed that, in contrast to the other 2 epitopes, IYVLVMLVL was not presented on HLA A24–positive fibroblast cells infected with recombinant vaccinia viruses expressing LMP2. Furthermore, ELISPOT assays with an epitope-specific CTL clone demonstrated that the presentation was partially restored by pretreatment of the fibroblast cells with interferon-γ. The epitope was presented on transporters associated with antigen processing (TAP)–negative T2 cells transfected with plasmids encoding HLA A*2402 and the minimal epitope, indicating that the presentation is TAP independent. In conclusion, the 3 epitopes thus defined could be useful for studying EBV-specific CD8+ T-cell responses among populations positive for HLA A*2402.
Serum amyloid A induces IL-8 secretion through a G protein–coupled receptor, FPRL1/LXA4R
Authors: He Rong , Sang Hairong , Ye Richard D.
Published: January 2003

Host response to injury and infection is accompanied by a rapid rise in the blood of acute-phase proteins such as serum amyloid A (SAA). Although SAA has been used as a marker for inflammatory diseases, its role in the modulation of inflammation and immunity has not been defined. Human neutrophils respond to SAA with secretion of the proinflammatory cytokines interleukin 8 (IL-8) and, to a lesser extent, tumor necrosis factor α (TNF-α). The induction of IL-8 secretion by SAA involves both transcription and translation and correlates with activation of nuclear factor κB (NF-κB). The proximal signaling events induced by SAA include mobilization of intracellular Ca2+ and activation of the mitogen-activated protein kinases ERK1/2 and p38, both required for the induced IL-8 secretion. Pertussis toxin effectively blocks SAA-induced IL-8 secretion indicating involvement of a Gi-coupled receptor. Overexpression of FPRL1/LXA4R in HeLa cells results in a significant increase of the expression of NF-κB and IL-8 luciferase reporters by SAA, and an antibody against the N-terminal domain of FPRL1/LXA4R inhibits IL-8 secretion. Lipoxin A4, which binds to FPRL1/LXA4R specifically, decreases SAA-induced IL-8 secretion significantly. Collectively, these results indicate that the cytokine-like property of SAA is manifested through activation of the Gi-coupled FPRL1/LXA4R, which has been known to mediate the anti-inflammatory effects of lipoxin A4. The ability of FPRL1/LXA4R to mediate 2 drastically different and opposite functions suggests that it plays a role in the modulation of inflammatory and immune responses.
LIR9, an immunoglobulin-superfamily–activating receptor, is expressed as a transmembrane and as a secreted molecule
Authors: Borges Luis , Kubin Marek , Kuhlman Tracy
Published: January 2003

LIRs are immunoglobulinlike receptors that have activating and inhibitory functions in leukocytes. Here we report the identification of the first LIR family member, LIR9, expressed as a membrane-bound receptor and as a secreted molecule. We identified 4 different forms of LIR9, 2 of which encode transmembrane molecules and 2 encode secreted molecules. The transmembrane forms of LIR9 contain a short cytoplasmic domain and a charged arginine residue within the transmembrane region that is likely to mediate its association with another coreceptor. LIR9 is mostly expressed in myeloid cells, including monocytes and neutrophils. Cross-linking of LIR9 on the surfaces of monocytes induces calcium flux and secretion of the proinflammatory cytokines interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and IL-6, indicating that LIR9 could play a role in triggering innate immune responses.
Specific inhibition of bcr-abl gene expression by small interfering RNA
Authors: Scherr Michaela , Battmer Karin , Winkler Thomas , Heidenreich Olaf , Ganser Arnold , Eder Matthias
Published: January 2003

Small interfering RNAs (siRNAs) were designed to target thebcr-abl oncogene, which causes chronic myeloid leukemia (CML) and bcr-abl–positive acute lymphoblastic leukemia (ALL). Chemically synthesized anti–bcr-abl siRNAs were selected using reporter gene constructs and were found to reduce bcr-abl mRNA up to 87% in bcr-abl–positive cell lines and in primary cells from CML patients. This mRNA reduction was specific for bcr-abl because c-abl and c-bcr mRNA levels remained unaffected. Furthermore, protein expression of BCR-ABL and of laminA/C was reduced by specific siRNAs up to 80% in bcr-abl–positive and normal CD34+ cells, respectively. Finally, anti–bcr-abl siRNA inhibited BCR-ABL–dependent, but not cytokine-dependent, proliferation in a bcr-abl–positive cell line. These data demonstrate that siRNA can specifically and efficiently interfere with the expression of an oncogenic fusion gene in hematopoietic cells.
Mutations in the VHL gene in sporadic apparently congenital polycythemia
Authors: Pastore Yves D. , Jelinek Jaroslav , Ang Sonny , Guan Yongli , Liu Enli , Jedlickova Katerina , Krishnamurti Lakshmanan , Prchal Josef T.
Published: January 2003

The congenital polycythemic disorders with elevated erythropoietin (Epo) have been until recently an enigma, and abnormality in the hypoxia-sensing pathway has been hypothesized as a possible mechanism. The tumor suppressor von Hippel-Lindau (VHL) participates in the hypoxia-sensing pathway, as it binds to the proline-hydroxylated form of the hypoxia-inducible factor 1α (HIF-1α) and mediates its ubiquitination and proteosomal degradation. The loss of VHL function may result in the accumulation of HIF-1α and overproduction of HIF-1 downstream target genes including Epo. VHL syndrome is an autosomal dominant disorder predisposing to the development of tumors, due to inherited mutations in the VHL gene. Some rare patients with VHL syndrome have polycythemia, which has been attributed to Epo production by a tumor. It was recently found that homozygosity for theVHL Arg200Trp mutation is the cause of Chuvash polycythemia, an autosomal recessive polycythemic disorder characterized by elevated serum Epo and hypersensitivity of erythroid cells to Epo. We evaluated the role of VHL in 8 children with a history of polycythemia and an elevated serum Epo level and found 3 different germline VHL mutations in 4 of them. One child was homozygous for the Arg200Trp VHL mutation, and another compound heterozygous for the Arg200Trp and the Val130Leu mutations. Two children (siblings) were heterozygous for an Asp126Tyr mutation, one of them fulfilling some criteria of VHL syndrome. We propose that mutations of the VHL gene represent an important cause of pediatric sporadic polycythemias with an inappropriately high serum Epo concentration.
Molecular assembly of the ternary granulocyte-macrophage colony-stimulating factor receptor complex
Authors: McClure Barbara J. , Hercus Timothy R. , Cambareri Bronwyn A. , Woodcock Joanna M. , Bagley Christopher J. , Howlett Geoff J. , Lopez Angel F.
Published: January 2003

Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a hematopoietic cytokine that stimulates the production and functional activity of granulocytes and macrophages, properties that have encouraged its clinical use in bone marrow transplantation and in certain infectious diseases. Despite the importance of GM-CSF in regulating myeloid cell numbers and function, little is known about the exact composition and mechanism of assembly of the GM-CSF receptor complex. We have now produced soluble forms of the GM-CSF receptor α chain (sGMRα) and β chain (sβc) and utilized GM-CSF, the GM-CSF antagonist E21R (Glu21Arg), and the βc-blocking monoclonal antibody BION-1 to define the molecular assembly of the GM-CSF receptor complex. We found that GM-CSF and E21R were able to form low-affinity, binary complexes with sGMRα, each having a stoichiometry of 1:1. Importantly, GM-CSF but not E21R formed a ternary complex with sGMRα and sβc, and this complex could be disrupted by E21R. Significantly, size-exclusion chromatography, analytical ultracentrifugation, and radioactive tracer experiments indicated that the ternary complex is composed of one sβc dimer with a single molecule each of sGMRα and of GM-CSF. In addition, a hitherto unrecognized direct interaction between βc and GM-CSF was detected that was absent with E21R and was abolished by BION-1. These results demonstrate a novel mechanism of cytokine receptor assembly likely to apply also to interleukin-3 (IL-3) and IL-5 and have implications for our molecular understanding and potential manipulation of GM-CSF activation of its receptor.
Cell cycle deregulation in B-cell lymphomas
Authors: Sánchez-Beato Margarita , Sánchez-Aguilera Abel , Piris Miguel A.
Published: January 2003

Disruption of the physiologic balance between cell proliferation and death is a universal feature of all cancers. In general terms, human B-cell lymphomas can be subdivided into 2 main groups, low- and high-growth fraction lymphomas, according to the mechanisms through which this imbalance is achieved. Most types of low-growth fraction lymphomas are initiated by molecular events resulting in the inhibition of apoptosis, such as translocations affecting BCL2, in follicular lymphoma, or BCL10 and API2/MLT1, in mucosa-associated lymphoid tissue (MALT) lymphomas. This results in cell accumulation as a consequence of prolonged cell survival. In contrast, high-growth fraction lymphomas are characterized by an enhanced proliferative activity, as a result of the deregulation of oncogenes with cell cycle regulatory functions, such asBCL6, in large B-cell lymphoma, or c-myc, in Burkitt lymphoma. Low- and high-growth fraction lymphomas are both able to accumulate other alterations in cell cycle regulation, most frequently involving tumor suppressor genes such asp16INK4a, p53, andp27KIP1. As a consequence, these tumors behave as highly aggressive lymphomas. The simultaneous inactivation of several of these regulators confers increased aggressivity and proliferative advantage to tumoral cells. In this review we discuss our current knowledge of the alterations in each of these pathways, with special emphasis on the deregulation of cell cycle progression, in an attempt to integrate the available information within a global model that describes the contribution of these molecular changes to the genesis and progression of B-cell lymphomas.
The peripheral cannabinoid receptor Cb2, a novel oncoprotein, induces a reversible block in neutrophilic differentiation
Authors: Jordà Meritxell Alberich , Löwenberg Bob , Delwel Ruud
Published: January 2003

We previously identified a novel common virus integration site, Evi11, by means of retroviral insertional mutagenesis. We demonstrated that the gene encoding the peripheral cannabinoid receptor (Cb2) is the potential target, suggesting that Cb2 is a proto-oncogene. To elucidate a role for this G protein–coupled receptor (GPCR) in leukemic transformation we generated a Cb2-EGFP cDNA construct that was introduced into 32D/G-CSF-R cells. These cells require interleukin 3 (IL-3) to proliferate in vitro, whereas in the presence of granulocyte–colony-stimulating factor (G-CSF) they differentiate toward mature neutrophils. We demonstrate that 32D/G-CSF-R/Cb2-EGFP cells migrate in a transwell assay in reponse to the Cb2 ligand 2-arachidonoylglycerol (2-AG), indicating that the fusion protein was functional. When cultured in the presence of G-CSF neutrophilic differentiation of Cb2-EGFP–expressing 32D/G-CSF-R cells was completely blocked. Moreover, a Cb2-specific antagonist fully recovered the G-CSF–induced neutrophilic differentiation of 32D/G-CSF-R/Cb2-EGFP cells. To investigate which signal transduction pathway(s) may be involved in the block of neutrophilic maturation, differentiation experiments were carried out using specific inhibitors of signaling routes. Interestingly, full rescue of G-CSF–induced neutrophilic differentiation was observed when cells were cultured with the mitogen-induced extracellular kinase (MEK) inhibitors, PD98059 or U0126, and partial recovery was detected with the phosphoinositide 3-kinase (PI3-K) inhibitor LY-294002. These studies demonstrate that the Cb2 receptor is an oncoprotein that blocks neutrophilic differentiation when overexpressed in myeloid precursor cells. Cb2 appears to mediate its activity through MEK/extracellular signal-related kinase (ERK) and PI3-K pathways.
Dendritic cells overexpressing CD95 (Fas) ligand elicit vigorous allospecific T-cell responses in vivo
Authors: Buonocore Sofia , Paulart Frédéric , Le Moine Alain , Braun Michel , Salmon Isabelle , Van Meirvenne Sonja , Thielemans Kris , Goldman Michel , Flamand Véronique
Published: January 2003

Dendritic cells (DCs) genetically engineered to overexpress CD95 (Fas) ligand (CD95L-DC) were proposed as tools to induce peripheral tolerance to alloantigens. Herein, we observed that CD95L-DC obtained after retroviral gene transfer in bone marrow (BM) precursors derived from CD95-deficient (lpr/lpr) mice elicit much stronger allospecific type 1 helper T-cell and cytotoxic T-cell activities than control DCs upon injection in vivo, although they induce lower T-cell responses in vitro. Indeed, a single injection of CD95L-DC prepared from C57BL/6 mice was sufficient to prime bm13 recipients for acute rejection of C57BL/6 skin allografts that were otherwise tolerated in the context of this single weak major histocompatibility complex (MHC) class I incompatibility. Massive neutrophil infiltrates depending on interleukin (IL)–1 signaling were observed at sites of CD95L-DC injection. Experiments in IL-1 receptor–deficient mice or in animals injected with depleting anti-Gr1 monoclonal antibody (mAb) established that neutrophil recruitment is required for the development of vigorous T-cell responses after injection of CD95L-DC in vivo.
Immunologic potential of donor lymphocytes expressing a suicide gene for early immune reconstitution after hematopoietic T-cell–depleted stem cell transplantation
Authors: Marktel Sarah , Magnani Zulma , Ciceri Fabio , Cazzaniga Sabrina , Riddell Stanley R. , Traversari Catia , Bordignon Claudio , Bonini Chiara
Published: January 2003

We have previously shown that the infusion of donor lymphocytes expressing the herpes simplex virus thymidine kinase(HSV-tk) gene is an efficient tool for controlling graft-versus-host disease (GVHD) while preserving the graft-versus-leukemia (GVL) effect. In addition to the GVL effect, the administration of donor HSV-tk+ cells could have a clinical impact in promoting immune reconstitution after T-cell–depleted stem cell transplantation (SCT). To explore this hypothesis, we have investigated whether in vitro polyclonal activation, retroviral transduction, immunoselection, and expansion affect the immune competence of donor T cells. We have observed that, after appropriate in vitro manipulation, T cells specific for antigens relevant in the context of SCT are preserved in terms of frequency, expression of T-cell receptor, proliferation, cytokine secretion, and lytic activity. A reduction in the frequency of allospecific T-cell precursors is observed after prolonged T-cell culture, suggesting that cell manipulation protocols involving a short culture time and high transduction efficiency are needed. Finally, the long-term persistence of HSV-tk+ cells was observed in a patient treated in the GVL clinical trial, and a reversion of the phenotype of HSV-tk+ cells from CD45RO+ to CD45RA+ was documented more than 2 years after the infusion. Based on all this evidence, we propose a clinical study of preemptive infusions of donor HSV-tk+ T cells after SCT from haploidentical donors to provide early immune reconstitution against infection and potential immune protection against disease recurrence.