bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of Materials for the Clinical Assessment of Speech Recognition
Authors: Bochner Joseph H. , Garrison Wayne M. , Sussman Joan E. , Burkard Robert F.
Published: April 2006

The purpose of this investigation was to evaluate the validity and reliability of materials designed for an assessment procedure capable of making meaningful distinctions in speech recognition ability among individuals having mild-to-moderate hearing losses. Sets of phonetic contrasts were presented within sentence contexts to 53 listeners (22 normal hearing, 31 hearing impaired) in 4 listening conditions (quiet and with background competition at signal-to-noise ratios of +5, 0, and –5 dB). The listeners were asked to discriminate pairs of sentences (e.g., "The man hid the dog" and "The man hit the dog") using
same-different
judgments. Their performances were analyzed in a manner enabling comparisons among items in terms of the classification of phonetic contrasts. Listener performance was also compared to performance on a set of independent variables, including the W-22 and QuickSIN speech tests, high-frequency hearing loss, speech reception threshold, listener age, and others. Results indicated that the new materials distinguished the normal-hearing from the hearing-impaired group and that listener performance (a) declined about 17% for each 5 dB decrement in SNR and (b) was influenced by the phonetic content of items in a manner similar to that reported by G. A. Miller and P. E. Nicely (1955). The performances of the hearing-impaired listeners were much more strongly related to high-frequency hearing loss, listener age, and other variables than were their performances on either the W-22 or QuickSIN tests. These findings are discussed with specific reference to the use of a mathematical model (i.e., the Rasch model for person measurement) for scaling items along a continuum of difficulty. The mathematical model and associated item difficulty values will serve as the basis for construction of a clinically useful computerized, adaptive test of speech recognition ability known as the Speech Sound Pattern Discrimination Test (Bochner, J., Garrison, W., Palmer, L., MacKenzie, D., & Braveman, A., 1997).
The Camperdown Program
Authors: O'Brian Sue , Onslow Mark , Cream Angela , Packman Ann
Published: April 2006

Considerable research has been directed at the outcomes of prolonged-speech (PS) treatment for the control of chronic stuttering, but little research to date has focused on the PS treatment process. This report examines a Stage 2 clinical trial of a reconceptualized PS treatment model known as the Camperdown Program. This program requires fewer clinician hours than traditional programs and has no formal transfer phase. Additionally, it incorporates the following treatment process innovations, which replace treatment process components that are intuitively and empirically problematic: (a) PS is taught without incorporating target behaviors in clinician instruction, (b) participants learn to control stuttering without programmed instruction, and (c) the treatment process does not involve clinician identification of stuttering moments. Thirty participants were initially enrolled in the trial. Final outcome data are presented for the 16 participants who completed all trial requirements, including 12 months posttreatment data collection. These 16 participants showed minimal or no stuttering in everyday speaking situations for up to 12 months after entering the maintenance program, with speech rates in the normal range. Speech naturalness and social validation data were also favorable. Although self-report data generally confirmed the speech data, the results were not as positive. The present outcomes were achieved in a mean of 20 hours of clinic attendance per participant, which is much fewer than the hours required by treatment programs reported recently that run intensively over 2–3 weeks. The promise of this Stage 2 clinical trial has led the authors to initiate a Stage 3 randomized controlled trial of the Camperdown Program.
Explaining and Controlling Regression to the Mean in Longitudinal Research Designs
Authors: Zhang Xuyang , Tomblin J. Bruce
Published: April 2006

This tutorial is concerned with examining how regression to the mean influences research findings in longitudinal studies of clinical populations. In such studies participants are often obtained because of performance that deviates systematically from the population mean and are then subsequently studied with respect to change in the trait used for this selection. It is shown that in such research there is a potential for the estimates of change to be erroneous due to the effect of regression to the mean. The source of the regression effect is shown to arise from measurement error and a sampling bias of this measurement error in the process of selecting on extreme scores. It is also shown that regression effects are greater with measures that are less reliable and with samples that are selected with more extreme scores. Furthermore, it is shown that regression effects are particularly prominent when measures of change are based on changes in dichotomous states formed from quantitative, normally distributed traits. In addition to a formal analysis of the regression to the mean, the features of regression to the mean are demonstrated via a simulation.
Respiratory Kinematics During Vocalization and Nonspeech Respiration in Children From 9 to 48 Months
Authors: Connaghan Kathryn P. , Moore Christopher A. , Higashakawa Masahiko
Published: April 2006

The development of respiratory drive for vocalization was studied by observing chest wall kinematics longitudinally in 4 typically developing children from the age of 9 to 48 months. Measurements of the relative contribution of rib cage and abdominal movement during vocalization (i.e., babbling and true words) and rest breathing were obtained every 3 months using respiratory plethysmography (RespitraceTM). Extending earlier findings in 15-month-olds, 2 methods of analysis of rib cage and abdominal movement were used: (a) a dynamic index of the strength of coupling between the rib cage and abdomen, and (b) a classification scheme describing the moment-by-moment changes in each of the 2 components (C. A. Moore, T. J. Caulfield, & J. R. Green, 2001). The developmental course of relative chest wall kinematics differed between vocalization and rest breathing. The coupling of rib cage and abdomen during vocalization weakened significantly with development, whereas it remained consistently strong for rest breathing throughout the observed period. The developmental changes in frequency of occurrence of relative moment-by-moment changes varied across movement type. The results support previous findings that speech breathing is distinct from rest breathing based on the relative contributions of the rib cage and abdomen. Longitudinal changes are likely responsive to anatomic development, including changes to rib cage shape and compliance.
Negative Concord in Child African American English
Authors: Coles-White D'Jaris
Published: April 2006

In this study, African American English (AAE)-speaking children's comprehension of 2 different types of double negative sentences was examined and contrasted with that of a comparison group of Standard American English (SAE)-speaking children. The first type of double negative, negative concord, involves 2 negative elements in a sentence that are interpreted together as single negation. The second type of double negative, called true double negation, involves 2 negatives that are interpreted as independent negatives. A cross-sectional cohort of 61 (35 AAE, 26 SAE) typically developing children ranging in age from 5;2 (years;months) to 7;11 participated. The children responded to story-based grammatical judgment tasks that required them to differentiate between negative concord and true double negation. Results revealed no statistically significant differences between AAE- and SAE-speaking children in the way they interpreted negative concord and true double negation. However, there were significantly more correct responses to negative concord sentences across combined groups. In particular, the older children (i.e., 7-year-olds) produced more correct responses to negative concord than did the younger group (i.e., 5-year-olds). Explanations for these findings are framed in terms of children's knowledge about sentences with 2 negatives, the constraints affecting the interpretation of 2 negatives that include negative concord, and the clinical importance of negative concord for assessing specific language impairment in child AAE speakers.
The Effect of Asymmetrical Signal Degradation on Binaural Speech Recognition in Children and Adults
Authors: Rothpletz Ann M. , Tharpe Anne Marie , Grantham D. Wesley
Published: April 2006

To determine the effect of asymmetrical signal degradation on binaural speech recognition, 28 children and 14 adults were administered a sentence recognition task amidst multitalker babble. There were 3 listening conditions: (a) monaural, with mild degradation in 1 ear; (b) binaural, with mild degradation in both ears (symmetric degradation); and (c) binaural, with mild degradation in one ear and severe degradation in the other ear (asymmetric degradation). Sentences and babble were degraded digitally to simulate mild and severe cochlear hearing loss. All participants demonstrated significant binaural advantage (average of 7 dB) when listening to symmetrically degraded signals as compared to when listening monaurally. In contrast, adults and children achieved little or no binaural benefit, on average, when listening to asymmetrically degraded signals. Moreover, overall performance of the adults was significantly worse when listening to binaural asymmetrically degraded signals than when listening to monaural signals, thus demonstrating evidence of binaural interference. In contrast to our original speculations, however, children did not show an overall demonstration of binaural interference. Relative performance in the binaural-asymmetric and the monaural conditions was not influenced by which ear (right or left) received the more degraded signal.
Grammatical Tense Deficits in Children With SLI and Nonspecific Language Impairment
Authors: Rice Mabel L. , Tomblin J. Bruce , Hoffman Lesa , Richman W. Allen , Marquis Janet
Published: April 2006

The relationship between children’s language acquisition and their nonverbal intelligence has a long tradition of scientific inquiry. Current attention focuses on the use of nonverbal IQ level as an exclusionary criterion in the definition of specific language impairment (SLI). Grammatical tense deficits are known as a clinical marker of SLI, but the relationship with nonverbal intelligence below the normal range has not previously been systematically studied. This study documents the levels of grammatical tense acquisition (for third-person singular -s, regular and irregular past tense morphology) in a large, epidemiologically ascertained sample of kindergarten children that comprises 4 groups: 130 children with SLI, 100 children with nonspecific language impairments (NLI), 73 children with low cognitive levels but language within normal limits (LC), and 117 unaffected control children. The study also documents the longitudinal course of acquisition for the SLI and NLI children between the ages of 6 and 10 years. The LC group did not differ from the unaffected controls at kindergarten, showing a dissociation of nonverbal intelligence and grammatical tense marking, so that low levels of nonverbal intelligence did not necessarily yield low levels of grammatical tense. The NLI group’s level of performance was lower than that of the SLI group and showed a greater delay in resolution of the overgeneralization phase of irregular past tense mastery, indicating qualitative differences in growth. Implications for clinical groupings for research and clinical purposes are discussed.
Comparison of Speech Perception in Background Noise With Acceptance of Background Noise in Aided and Unaided Conditions
Authors: Nabelek Anna K. , Tampas Joanna W. , Burchfield Samuel B.
Published: April 2006

Background noise is a significant factor influencing hearing-aid satisfaction and is a major reason for rejection of hearing aids. Attempts have been made by previous researchers to relate the use of hearing aids to speech perception in noise (SPIN), with an expectation of improved speech perception followed by an increased acceptance of hearing aids. Unfortunately, SPIN was not related to hearing-aid use or satisfaction. A new measure of listener reaction to background noise has been proposed. The acceptable noise level (ANL), expressed in decibels, is defined as a difference between the most comfortable listening level for speech and the highest background noise level that is acceptable when listening to and following a story. The ANL measure assumes that speech understanding in noise may not be as important as is the willingness to listen in the presence of noise. It has been established that people who accept background noise have smaller ANLs and tend to be "good" users of hearing aids. Conversely, people who cannot accept background noise have larger ANLs and may only use hearing aids occasionally or reject them altogether. Because this is a new measure, it was important to determine the reliability of the ANL over time with and without hearing aids, to determine the effect of acclimatization to hearing aids, and to compare the ANL to well-established measures such as speech perception scores collected with the SPIN test. Results from 50 listeners indicate that for both good and occasional hearing aid users, the ANL is comparable in reliability to the SPIN test and that both measures do not change with acclimatization. The ANLs and SPIN scores are unrelated. Although the SPIN scores improve with amplification, the ANLs are unaffected by amplification, suggesting that the ANL is inherent to an individual and can be established prior to hearing aid fitting as a possible predictor of hearing-aid use.

KEY WORDS: background noise, hearing aids, acceptable noise level, speech perception in noise
Effect of F2 Intensity on Identity of /u/ in Degraded Listening Conditions
Authors: Hedrick Mark S. , Nabelek Anna K.
Published: April 2006

The current study investigated the influence of the second formant (F2) intensity on vowel labeling along a /u/-/i/ continuum. Twenty-two listeners with normal-hearing (NH) sensitivity and 14 listeners with sensorineural hearing impairment (HI) were initially presented 2 stimuli for which the F2 intensity differed by 20 dB. The listeners were asked to label the 2 stimuli categorically as /u/ or /i/. After passing this criterion test, listeners were presented 9 stimuli whose F2 intensity varied within the 20-dB range. The 9 stimuli were evaluated in 3 listening conditions: in quiet, in the presence of a continuous speech spectrum noise (0-dB signal-to-noise ratio), and in the presence of reverberation (
T
= 1.0 s). The intensity manipulation altered the vowel labeling of NH listeners and yielded a differential effect in noise versus reverberation. Only 5 of the HI listeners were able to pass the criterion test, and of these 5, only 2 were able to label the 9 stimuli categorically. Results from HI listeners suggest problems in categorizing spectral shape.
Differences at 17 Months
Authors: Koster Charlotte , Been Pieter H. , Krikhaar Evelien M. , Zwarts Frans , Diepstra Heidi D. , Leeuwen Theo H. Van
Published: April 2006

Productive vocabulary composition is investigated in 17-month-old children who are participating in an ongoing longitudinal dyslexia research project in the Netherlands. The project is searching for early precursors for dyslexia and follows a group of children who are genetically at risk for dyslexia and a control group during the first 10 years of their lives. Among other measures, the Dutch version of the MacArthur Communicative Development Inventory: Words and Sentences (N-CDI) is used to investigate early vocabulary development. In this article, the first N-CDI results from the 2 groups of 17-month-old children are compared with each other, with other cross-sectional, cross-linguistic studies, and with a similar Finnish longitudinal dyslexia project. The Dutch children show the same general acquisition pattern as documented for other languages, but there are significant differences between the two groups of 17-month-old children in total number of words produced and in the linguistic composition of their productive vocabulary.
An Investigation of Speech Perception in Children With Specific Language Impairment on a Continuum of Formant Transition Duration
Authors: Burlingame Elizabeth , Sussman Harvey M. , Gillam Ronald B. , Hay Jessica F.
Published: April 2006

Fifteen children diagnosed with specific language impairment (SLI) and 15 typically developing (TD) children were tested for identification performance on 2 synthetic speech continua varying in formant transition durations (FTDs). One continuum varied from /ba/ to /wa/, and the other varied from /da/ to /ja/. Variousd'-related measures from signal detection theory were used to compare category boundaries and indirectly derive sensitivity to phonetic changes in category tokens along each continuum. The SLI group showed less consistent identification performance along the /ba/-/wa/ series relative to the TD group, as well as reduced sensitivity to phonetic changes along the continuum. On the /da/-/ja/ series, the SLI group revealed less consistent identification performance on the short FTD end but similar identification levels to the TD group at the long FTD end. The overall results support the contention that children with SLI reveal a deficiency in the processing of speech sounds at the level of segmental identity.
Multiple Looks in Speech Sound Discrimination in Adults
Authors: Holt Rachael Frush , Carney Arlene Earley
Published: April 2006

N. F. Viemeister and G. H. Wakefield's (1991) multiple looks hypothesis is a theoretical approach from the psychoacoustic literature that has promise for bridging the gap between results from speech perception research and results from psychoacoustic research. This hypothesis accounts for sensory detection data and predicts that if the "looks" at a stimulus are independent and information is combined optimally, sensitivity should increase for 2 pulses relative to 1 pulse. Specifically,
d
' (a bias-free measure of sensitivity) for 2 pulses should be larger than
d
' for 1 pulse. One speech discrimination paradigm that presents stimuli with multiple presentations is the change/no-change procedure. On a change trial, the standard and comparison stimuli differ; on a no-change trial, they are the same. Normal-hearing adults were tested using the change/no-change procedure with 3 consonant-vowel minimal pairs in combinations of 1, 2, and 4 repetitions of standard and comparison stimuli at various signal-to-noise ratios. If multiple looks extend to this procedure, performance should increase with higher repetition numbers. Performance increased with more presentations of the speech contrasts tested. The multiple looks hypothesis predicted performance better at low repetition numbers when performance was near
d
' values of 1.0 than at higher repetition numbers and higher performance levels.
General Review of Tinnitus
Authors: Henry James A. , Dennis Kyle C. , Schechter Martin A.
Published: April 2006

Tinnitus is an increasing health concern across all strata of the general population. Although an abundant amount of literature has addressed the many facets of tinnitus, wide-ranging differences in professional beliefs and attitudes persist concerning its clinical management. These differences are detrimental to tinnitus patients because the management they receive is based primarily on individual opinion (which can be biased) rather than on medical consensus. It is thus vitally important for the tinnitus professional community to work together to achieve consensus. To that end, this article provides a broad-based review of what is presently known about tinnitus, including prevalence, associated factors, theories of pathophysiology, psychological effects, effects on disability and handicap, workers' compensation issues, clinical assessment, and various forms of treatment. This summary of fundamental information has relevance to both clinical and research arenas.
Examination of Strength Training and Detraining Effects in Expiratory Muscles
Authors: Baker Susan , Davenport Paul , Sapienza Christine
Published: April 2006

Purpose:
The purpose of this study was to determine strength gains following expiratory muscle strength training (EMST) and to determine detraining effects when the training stimulus is removed.

Method:
Thirty-two healthy participants were enrolled in an EMST program. Sixteen participants trained for 4 weeks (Group 1) and 16 participants trained for 8 weeks (Group 2). All 32 participants were detrained for 8 weeks. Maximum expiratory pressure (MEP) was used to document change in expiratory muscle strength throughout the study.

Results:
Group 1 had a 41% increase and Group 2 had a 51% increase in MEP following the training. Mean MEP, for both groups, was significantly greater than baseline at the end of the training period (
p
= .0001), at the 4th week of detraining (
p
= .0001), and at the 8th week of detraining (
p
= .0001). The results also indicated that there was no significant difference in mean MEP between the groups at baseline, end of training, or throughout the detraining period (
p
= .960).

Discussion:
The results suggest that expiratory muscle strength gains following a 4- and 8-week EMST program do not differ significantly. Additionally, detraining rates do not appear to be dependent on length of training time.
Verb Learning in Children With SLI
Authors: Riches N. G. , Tomasello M. , Conti-Ramsden Gina
Published: April 2006

Purpose:
This study explored the effect of frequency (number of presentations), and spacing (period between presentations) on verb learning in children with specific language impairment (SLI). Children learn words more efficiently when presentations are frequent and appropriately spaced, and this study investigated whether children with SLI likewise benefit. Given that these children demonstrate greater frequency dependence and rapid forgetting of recently acquired words, an investigation of frequency and spacing in this population is especially warranted.

Method:
Twenty-four children with SLI (mean age 5;6 [years;months]) and 24 language-matched control children (mean age 3;4) were taught novel verbs during play sessions. In a repeated measures design, 4 experimental conditions combined frequency (12 or 18 presentations) and spacing (all presentations in 1 session, or spread over 4 days). Comprehension and production probes were administered after the final session and 1 week later.

Results:
Although the children with SLI benefited significantly from frequent and widely spaced presentations, there were no significant effect in the control group. The language-impaired children showed rapid forgetting.

Conclusions:
The frequency and spacing of presentations crucially affect the verb learning of children with SLI. A training regimen characterized by appropriately spaced intervals and moderate repetition will optimally benefit lexical learning.
Imaging of ferroelectric polarization in Pb(Mg1∕3Nb2∕3)O3–PbTiO3 crystals by scanning electro-optic microscopy
Authors: Tikhomirov O. , Labardi M. , Ascoli C. , Allegrini M. , Lebrun L.
Published: April 2006

Spatial distribution of the ferroelectric polarization in (1−x)Pb(Mg1∕3Nb2∕3)O3–xPbTiO3 single crystals with x=0.25 has been visualized using scanning confocal electro-optic microscopy. Domains showing different values and signs of the linear electro-optic effect are observed in both ⟨001⟩ and ⟨111⟩ oriented crystal plates in case of application of a symmetry-breaking dc electric field. Features of the observed images are explained on the basis of the electro-optic tensor analysis.
Determination of domain orientation in lead zirconate titanate ceramics by Raman spectroscopy
Authors: Pojprapai(Imlao) Soodkhet , Jones Jacob L. , Hoffman Mark
Published: April 2006

Raman spectroscopy was employed to investigate the domain orientations of poled and unpoled tetragonal lead zirconate titanate ceramics. Using backscattering geometry, the ceramics were rotated 360° relative to the polarization direction of the incident beam. The ratio of the crossed to parallel polarization intensities in the poled sample demonstrates periodicity with respect to the rotation angle, while that of the unpoled sample does not. The angular periodicity of the intensity ratio is related to the domain orientations through the Raman tensor. Raman spectroscopy is thereby demonstrated as a quantitative technique that can measure domain switching distributions in ferroelastic ceramics.
RETRACTED: Cell–cell signaling in
Xanthomonas campestris
involves an HD-GYP domain protein that functions in cyclic di-GMP turnover
Authors: Ryan Robert P. , Fouhy Yvonne , Lucey Jean F. , Crossman Lisa C. , Spiro Stephen , He Ya-Wen , Zhang Lian-Hui , Heeb Stephan , Cámara Miguel , Williams Paul , Dow J. Maxwell
Published: April 2006

HD-GYP is a protein domain of unknown biochemical function implicated in bacterial signaling and regulation. In the plant pathogen
Xanthomonas campestris
pv.
campestris
, the synthesis of virulence factors and dispersal of biofilms are positively controlled by a two-component signal transduction system comprising the HD-GYP domain regulatory protein RpfG and cognate sensor RpfC and by cell–cell signaling mediated by the diffusible signal molecule DSF (diffusible signal factor). The RpfG/RpfC two-component system has been implicated in DSF perception and signal transduction. Here we show that the role of RpfG is to degrade the unusual nucleotide cyclic di-GMP, an activity associated with the HD-GYP domain. Mutation of the conserved H and D residues of the isolated HD-GYP domain resulted in loss of both the enzymatic activity against cyclic di-GMP and the regulatory activity in virulence factor synthesis. Two other protein domains, GGDEF and EAL, are already implicated in the synthesis and degradation respectively of cyclic di-GMP. As with GGDEF and EAL domains, the HD-GYP domain is widely distributed in free-living bacteria and occurs in plant and animal pathogens, as well as beneficial symbionts and organisms associated with a range of environmental niches. Identification of the role of the HD-GYP domain thus increases our understanding of a signaling network whose importance to the lifestyle of diverse bacteria is now emerging.
Stepwise RNP assembly at the site of H/ACA RNA transcription in human cells
Authors: Darzacq Xavier , Kittur Nupur , Roy Sujayita , Shav-Tal Yaron , Singer Robert H. , Meier U. Thomas
Published: April 2006

Mammalian H/ACA RNPs are essential for ribosome biogenesis, premessenger RNA splicing, and telomere maintenance. These RNPs consist of four core proteins and one RNA, but it is not known how they assemble. By interrogating the site of H/ACA RNA transcription, we dissected their biogenesis in single cells and delineated the role of the non-core protein NAF1 in the process. NAF1 and all of the core proteins except GAR1 are recruited to the site of transcription. NAF1 binds one of the core proteins, NAP57, and shuttles between nucleus and cytoplasm. Both proteins are essential for stable H/ACA RNA accumulation. NAF1 and GAR1 bind NAP57 competitively, suggesting a sequential interaction. Our analyses indicate that NAF1 binds NAP57 and escorts it to the nascent H/ACA RNA and that GAR1 then replaces NAF1 to yield mature H/ACA RNPs in Cajal bodies and nucleoli.
Members of the NIMA-related Kinase Family Promote Disassembly of Cilia by Multiple Mechanisms
Authors: Wloga Dorota , Camba Amy , Rogowski Krzysztof , Manning Gerard , Jerka-Dziadosz Maria , Gaertig Jacek
Published: April 2006

The genome of Tetrahymena thermophila contains 39 loci encoding NIMA-related kinases (NRKs), an extraordinarily large number for a unicellular organism. Evolutionary analyses grouped these sequences into several subfamilies, some of which have orthologues in animals, whereas others are protist specific. When overproduced, NRKs of three subfamilies caused rapid shortening of cilia. Ultrastructural studies revealed that each NRK triggered ciliary resorption by a distinct mechanism that involved preferential depolymerization of a subset of axonemal microtubules, at either the distal or proximal end. Overexpression of a kinase-inactive variant caused lengthening of cilia, indicating that constitutive NRK-mediated resorption regulates the length of cilia. Each NRK preferentially resorbed a distinct subset of cilia, depending on the location along the anteroposterior axis. We also show that normal Tetrahymena cells maintain unequal length cilia. We propose that ciliates used a large number of NRK paralogues to differentially regulate the length of specific subsets of cilia in the same cell.
Evolutionary regime shifts in age and size at maturation of exploited fish stocks
Authors: de Roos André M , Boukal David S , Persson Lennart
Published: April 2006

Worldwide declines of fish stocks raise concerns about deleterious consequences of harvesting for stock abundances and individual life histories, and call for appropriate recovery strategies. Fishes in exploited stocks mature earlier at either larger or smaller sizes due to both genetic and plastic responses. The latter occur commonly when reduced competition for food leads to faster growth. Using a size-structured consumer–resource model, which accounts for both genetic and plastic responses, we show that fisheries-induced evolutionary changes in individual life history and stock properties can easily become irreversible. As a result of annual spawning, early maturation at small sizes and late maturation at large sizes can become alternative, evolutionarily and ecologically stable states under otherwise identical environmental conditions. Exploitation of late-maturing populations can then induce an evolutionary regime shift to smaller maturation sizes associated with stepwise, 1-year decreases in age at first reproduction. Complete and early fishing moratoria slowly reverse this process, but belated or partial closure of fisheries may accelerate or even instigate further evolution to smaller sizes at maturation. We suggest that stepwise decreases in maturation age can be used as early warnings of upcoming evolutionary changes, and should inspire timely restrictions of fisheries.
Water channels are important for osmotic adjustments of yeast cells at low temperature
Authors: Soveral Graça , Veiga Alexandra , Loureiro-Dias Maria C. , Tanghe An , Van Dijck Patrick , Moura Teresa F.
Published: April 2006

The importance of aquaporin expression in water permeability in Saccharomyces cerevisiae was assessed by measuring the osmotic water permeability coefficient (P
f) and the activation energies (E
a) from both hypo- and hypertonic experiments performed with whole protoplasts from four strains differing in aquaporin level of expression: parental, double-deleted and overexpressing AQY1 or AQY2. Double-deleted (lower P
f) and AQY1-overexpressing strains (higher P
f) presented linear Arrhenius plots with E
a consistent with fluxes mainly through the lipids [16·3 kcal mol−1 (68·2 kJ mol−1)] and with a strong contribution of channels [9·6 kcal mol−1 (40·2 kJ mol−1)], respectively. The Arrhenius plots for the parental (swelling experiments) and overexpressing AQY2 strains (swelling and shrinking experiments) were not linear, presenting a break point with a change in slope around 23 °C. The E
a values for these strains, calculated for temperatures ranging from 7 to 23 °C, were lower [9·5 kcal mol−1 (39·7 kJ mol−1)] than the values obtained from 23 to 38 °C [17 kcal mol−1 (71·1 kJ mol−1)]. This behaviour indicates that only in the lower temperature range did the water fluxes occur predominantly via the water channels. The permeabilities for each strain relative to the deletion strain show that an increase in permeability due to the presence of aquaporins was more relevant at low temperatures. Following our results, we propose that water channels play an important role for osmotic adjustment of yeast cells at low temperature.
Spatial and temporal organisation of the pre‐dispersal seed predator guild in a perennial legume, Vicia tenuifolia
Authors: Szentesi Árpád , Schmera Dénes , Jermy Tibor
Published: April 2006

Abstract.  1. The variability of species combinations and membership assembly patterns in an insect pre‐dispersal seed predator guild were studied at various spatial and temporal resolutions using presence/absence and abundance data in null models. The guild consists of seven beetle species (four bruchids and three curculionids) and one moth species that live on a perennial vetch, Vicia tenuifolia Roth (Leguminosae).

2. The seed predator guild varied considerably in the number of members and species combinations in space and time, and, contrary to expectations, there was no evidence of interspecific competition among guild members, supporting the view that other processes, including chance events, could contribute to guild formation.

3. It is concluded that, apart from the possibility of stochastic co‐occurrence, it is the narrow host specialisation that constrains seed predator members to participate in the guild, and small differences in habitat preference can also lead to spatial and temporal variation.
The influences of host plant and genetic resistance to Bacillus thuringiensis on trade‐offs between offspring number and growth rate in cabbage loopers, Trichoplusia ni
Authors: Janmaat Alida F. , Myers Judith H.
Published: April 2006

Abstract.  1. Variation in progeny size and quality is common among insects and this variation can strongly influence individual fitness. Larger progeny typically survive better and develop faster under adverse conditions and may have higher fecundity. Due to resource limitations, however, trade‐offs may arise between having fewer large offspring or more smaller ones.

2. For cabbage loopers, Trichoplusia ni, pepper leaves are a poorer larval host than cucumber or tomato leaves as indicated by survival, development rate, and body size. Moths reared on cucumber produced more slower growing offspring than those that had been reared on pepper, which produced fewer, faster growing progeny.

3. Traits conferring resistance to Bacillus thuringiensis (Bt) generally are associated with strong deleterious effects that may influence resource allocation and reproductive trade‐offs between progeny size and number.

4. Unlike the host‐plant related trade‐off between progeny size and fecundity observed among susceptible control moths, Bt‐resistant parents had both the lowest fecundity and smallest progeny size on all host plants. This finding suggests that the progeny size–number relationship is constrained in resistant individuals.
Severe Ecstasy poisoning in a toddler
Authors: Duffy M. R. , Swart M.
Published: April 2006

A 17‐month‐old toddler became critically ill after an accidental overdose with ‘Ecstasy’. A single tablet was quickly retrieved intact from under her tongue, but within 5 min the child developed generalised tonic‐clonic seizures requiring immediate transfer to hospital. She also had hyperthermia (38.5 °C), tachycardia (150 beats.min−1) and hypertension. Treatment to terminate the seizures necessitated intubation and ventilation, and cooling measures brought the temperature within normal limits. The child was admitted to the intensive care unit and made a rapid recovery. She was discharged to the ward 12 h later, and had no long‐term sequelae.
Myocardial perfusion in patients with typical chest pain and normal angiogram
Authors: Graf S. , Khorsand A. , Gwechenberger M. , Schütz M. , Kletter K. , Sochor H. , Dudczak R. , Maurer G. , Pirich C. , Porenta G. , Zehetgruber M.
Published: April 2006

Background  Approximately 10–30% of patients with typical chest pain present normal epicardial coronaries. In a proportion of these patients, angina is attributed to microvascular dysfunction. Previous studies investigating whether angina is the result of abnormal resting or stress perfusion are controversial but limited by varying inclusion criteria. Therefore, we investigated whether microvascular dysfunction in these patients is associated with perfusion abnormalities at rest or at stress.

Patients and methods  In 58 patients (39 female, 19 male, mean age 58 ± 10 years) with angina and normal angiogram as well as 10 control patients with atypical chest pain and normal coronaries (six female, four male, mean age 53 ± 11 years) myocardial blood flow (MBF) was measured at rest and under dipyridamole using 13N–ammonia PET. Resting MBF and coronary flow reserve (CFR) as the ratio of hyperaemic to resting MBF were corrected for rate – pressure – product (RPP): normalized resting MBF (MBFn) = MBF × 10 000/RPP and CFRn = CFR × RPP/10 000.

Results  Sixteen/58 patients had a normal CFRn (= 2·5; group I; CFRn: 3·1 ± 0·88); the same as the controls (CFRn: 3·3 ± 0·74). Forty‐two/58 patients presented a reduced CFRn (group II; CFRn: 1·78 ± 0·57). Group II had both a higher MBFn (group II: 1·30 ± 0·33 vs. Group I: 1·03 ± 0·26; P < 0·05 and vs. controls: 1·07 ± 0·19; P < 0·01) and a lower hyperaemic MBF (group II: 2·25 ± 0·76 mL g−1 min−1 vs. Group I: 3·07 ± 0·78 mL g−1 min−1; P < 0·001 and vs. controls: 3·41 ± 0·94 mL g−1 min−1; P < 0·0001).

Conclusion  Impaired CFRn in patients with typical angina and normal angiogram is owing to both an increased resting and reduced hyperaemic MBF. Therefore, PET represents a prerequisite for further studies to optimize treatment in individuals with anginal pain and normal coronary angiogram.
Effect of various implant coatings on biological responses in MG63 using cDNA microarray
Authors: KIM C. ‐S. , SOHN S. ‐H. , JEON S. ‐K. , KIM K. ‐N. , RYU J. ‐J. , KIM M. ‐K.
Published: April 2006

summary  During the process of bone formation, titanium (Ti) surface is an important factor in the modulation of osteoblastic function. This study was conducted in order to determine the effects of different Ti surfaces on the biological responses of a human osteoblast‐like cell line (MG63). MG63 cells were cultured on smooth (S), sandblasted large‐grit and acid etching (SLA), hydroxyapatite (HA), hydroxyfluoride (HF), titanium nitrate (TIN), and diamond‐like carbon (DLC) Ti. The morphology of these cells were assessed by SEM. The cDNAs prepared from the total RNAs of the MG63 were hybridized into a human cDNA microarray (1152 elements). The appearances of the surfaces observed by SEM were different on each of the six dental substrate types. The SLA and HA surfaces were determined to be rougher than the others. MG63 cells cultured on SLA and HA exhibited cell–matrix interactions. In the expression of genes involved in osseointegration, several genes, including bone morphogenetic protein, cadherin, integrin, and insulin‐like growth factors, were upregulated on the different surfaces. Several genes, including fibroblast growth factor receptor 4, Bcl 2‐related protein, and collagen, were downregulated on the different surfaces. The attachment and expression of key osteogenic regulatory genes were enhanced by the surface roughness of the dental materials used.
Postoperative elevated cortisol excretion is not associated with suppression of 6‐sulfatoxymelatonin excretion
Authors: Derenzo J. , Macknight B. , DiVittore N. A. , Bonafide C. P. , Cronin A. J.
Published: April 2006

This study tests the hypothesis that elevated postoperative excretion of cortisol is associated with suppression of the nocturnal excretion of 6‐sulfatoxymelatonin, the chief metabolite of the circadian hormone, melatonin. Postoperative patients demonstrate circadian rhythm disturbances and suppression of nocturnal melatonin plasma concentration. Since the nocturnal surge in melatonin concentration in normal volunteers is time‐locked to the circadian nadir of cortisol concentration, perhaps the attenuation of the nocturnal melatonin surge in postoperative patients results from prolonged elevation in the plasma cortisol concentration. In this observational study performed in 21 patients having unilateral hip or knee arthroplasty, urine was collected every 4 h for the first 48 h after surgery for measurement of urinary 6‐sulfatoxymelatonin (EIA) and free cortisol (RIA) excretion. The total (P <  0.05) and peak (P <  0.02) nocturnal 6‐sulfatoxymelatonin excretions were lower on the first than the second postoperative night. The nocturnal cortisol nadir preceded the 6‐sulfatoxymelatonin surge in 20% of the subjects on night 1 and in 75% of the subjects on night 2. The lack of a consistent relationship between the magnitude or timing of cortisol excretion and 6‐sulfatoxymelatonin excretion suggests that cortisol does not mediate postoperative 6‐sulfatoxymelatonin suppression.
The relationship between bispectral index and targeted propofol concentration is biphasic in patients with major burns
Authors: Han T‐H. , Lee J‐H. , Kwak In‐Suk , Kil H‐Y. , Han K‐W. , Kim K‐M.
Published: April 2006

Background:  Many pathophysiologic alterations in major burns can cause changes in the distribution of, and perhaps response to, drugs commonly used in anesthesia practice. This study was conducted to assess changes in bispectral index (BIS) caused by increasing the target propofol effect‐site concentration during a target‐controlled infusion (TCI) in major burns.

Methods:  Eighteen patients, ASA physical status 2 or 3, aged from 20 to 55 years old, weighing 50–70 kg, with major burns, scheduled for elective early escharectomy less than a week after injury were recruited. A further 18 ASA physical status class 1 or 2, non‐burns, age, sex‐ and weight‐matched adult patients scheduled for elective surgery under general anesthesia were recruited as controls. During anesthesia induction, target propofol effect‐site concentrations were increased by increments of 0.5 µg ml−1 up to 4.5 µg ml−1. The BIS responses to each target concentration using TCI were compared in both groups.

Results:  In the burns group, significantly greater BIS values relating to increasing propofol TCI were noted at deeper anesthesia when compared with controls; at ≥3.5 µg ml−1; mean BIS remained at a plateau of about 50. Patients with burns had higher cardiac indices, and lower hemoglobin and albumin concentrations than the controls. They consumed more vecuronium to maintain the same degree of neuromuscular blockade than the controls.

Conclusions:  In major burns, the final biphasic BIS responses appeared to be determined by numerous other variables such as BIS algorithm, TCI performance, and altered propofol pharmacokinetics and pharmacodynamics. According to our results the importance of an individually tailored approach, including careful anesthetic titration, based upon the patient's clinical condition and responses can not be overemphasized.
Sevoflurane induces less cerebral vasodilation than isoflurane at the same A‐line® autoregressive index level
Authors: Holmström A. , Åkeson J.
Published: April 2006

Background:  The use of sevoflurane in neuroanesthesia is still under debate. Comparison of dose‐dependent vasodilatory properties between sevoflurane and isoflurane, the more traditional neuroanesthetic agent, requires comparable dosing of the agents. A‐line® autoregressive index (AAI) provides reproducible individual measurement of anesthetic depth.

Methods:  Sevoflurane and isoflurane, in randomized order, were titrated to a stable AAI of 15–20 in each of 18 ASA I or II patients. The mean flow velocity (Vmca) and pulsatility index (PI) in the middle cerebral artery were measured with transcranial Doppler at an end‐tidal CO2 of 4.5%.

Results:  For sevoflurane Vmca was 18% lower [95% confidence interval (CI) 12–22%; P < 0.00001] and PI was 23% higher (95% CI 12–33%; P = 0.0013) than for isoflurane. Mean arterial blood pressure did not differ between the two agents. The minimum alveolar concentration (MAC) fraction necessary to reach the intended AAI level was 13% higher (95% CI 5–20%; P = 0.0079) with sevoflurane than with isoflurane.

Conclusion:  Sevoflurane induced less cerebral vasodilation than isoflurane at the same depth of anesthesia, measured by AAI, and hence seems more favorable for clinical neuroanesthesia. In our opinion the difference between sevoflurane and isoflurane in the MAC fraction required to attain the same AAI level demonstrates the limitations of MAC in defining the level of anesthesia.
Microdialysis for measurement of hepatic and systemic nitric oxide biosynthesis in septic rats
Authors: Huang C.‐J. , Tsai P.‐S. , Pan W. H. T. , Skimming J. W.
Published: April 2006

Background:  We sought to compare two techniques, microdialysis and repeated blood withdrawal, for serial assessment of hepatic and systemic nitric oxide (NO) biosynthesis in septic rats.

Methods:  Rats were randomly allocated to either microdialysis or blood withdrawal groups. Two microdialysis probes, one in liver and the other in right atrium, were placed in rats in the microdialysis group. Half of the rats from each group were then given lipopolysaccharide (LPS) to induce NO production. The other half of the rats from each group were injected with vehicle (normal saline) to serve as controls. In the microdialysis group, dialysate (30 µl) was collected every 30 min. In the blood withdrawal group, 0.3 ml of blood was drawn every 30 min. Sampling was performed up to 6 h after injection of LPS or vehicle. Hemodynamics, hepatic and systemic NO concentrations, and iNOS expression in harvested liver tissues were assayed.

Results:  Repeated blood withdrawal by itself caused a significant decrease in blood pressure and induced hepatic iNOS expression. Microdialysis, on the contrary, reliably detected LPS‐induced NO production without resulting either in hemodynamic changes or in iNOS induction in liver tissue.

Conclusions:  Microdialysis provides serial measure of hepatic and systemic NO concentrations in LPS‐treated rats without the need for removal of tissue.
Long‐term comparison of sevelamer hydrochloride to calcium‐containing phosphate binders
Authors: BREWSTER URSULA C , CIAMPI MARC A , ABU‐ALFA ALI K , REILLY ROBERT F
Published: April 2006

Aim:  In patients with end‐stage renal disease (ESRD), hyperphosphataemia and an elevated calcium‐phosphorus (Ca‐P) product contribute to morbidity and mortality. Suggested target goals for serum phosphorus concentration and calcium‐phosphorus product have recently been lowered. As a result, long‐term comparative studies of the efficacy of phosphate binders are critical. This study compares the long‐term efficacy of sevelamer hydrochloride to calcium‐containing binders (CCB).

Methods:  A retrospective chart review was conducted in 30 patients receiving sevelamer hydrochloride for >1 years and 25 patients receiving CCB.

Results:  Patients on sevelamer hydrochloride had lower serum bicarbonate concentration than those on CCB, 18.6 ± 2.7 versus 20.3 ± 1.8 mmol/L (P = 0.0017). Serum phosphorus concentration was higher in patients on sevelamer hydrochloride compared to CCB 2.10 ± 0.87 versus 1.74 ± 0.28 mmol/L (P = 0.0013), as was the Ca‐P product 4.97 ± 0.94 mmol2/L2 (62.1 ± 11.8 mg2/dL2) versus 3.97 ± 1.18 mmol2/L2 (49.7 ± 14.7 mg2/dL2), P = 0.0009). Only 36% of patients on sevelamer hydrochloride compared with 68% on CCB (P = 0.015) met the serum phosphorus goal of ≤1.78 mmol/L.

Conclusion:  Patients on sevelamer hydrochloride for >1 years compared to those on CCB had a lower serum bicarbonate concentration, a higher serum phosphorus concentration and a higher Ca‐P product. Clinicians should balance the increase in calcium load with CCB versus the cost and effectiveness of sevelamer hydrochloride in choosing a phosphate binder for ESRD patients.