bluuebunny/crossref_metadata_2025 huggingface dataset:
Nearly Neutrality and the Evolution of Codon Usage Bias in Eukaryotic Genomes
Authors: Subramanian Sankar
Published: April 2008

Here I show that the mean codon usage bias of a genome, and of the lowly expressed genes in a genome, is largely similar across eukaryotes ranging from unicellular protists to vertebrates. Conversely, this bias in housekeeping genes and in highly expressed genes has a remarkable inverse relationship with species generation time that varies by more than four orders of magnitude. The relevance of these results to the nearly neutral theory of molecular evolution is discussed.
Basolateral Junctions Utilize Warts Signaling to Control Epithelial-Mesenchymal Transition and Proliferation Crucial For Migration and Invasion of Drosophila Ovarian Epithelial Cells
Authors: Zhao Min , Szafranski Przemyslaw , Hall Chad Albert , Goode Scott
Published: April 2008

Fasciclin2 (Fas2) and Discslarge (Dlg) localize to the basolateral junction (BLJ) of Drosophila follicle epithelial cells and inhibit their proliferation and invasion. To identify a BLJ signaling pathway we completed a genomewide screen for mutants that enhance dlg tumorigenesis. We identified two genes that encode known BLJ scaffolding proteins, lethal giant larvae (lgl) and scribble (scrib), and several not previously associated with BLJ function, including warts (wts) and roughened eye (roe), which encode a serine–threonine kinase and a transcription factor, respectively. Like scrib, wts and roe also enhance Fas2 and lgl tumorigenesis. Further, scrib, wts, and roe block border cell migration, and cause noninvasive tumors that resemble dlg partial loss of function, suggesting that the BLJ utilizes Wts signaling to repress EMT and proliferation, but not motility. Apicolateral junction proteins Fat (Ft), Expanded (Ex), and Merlin (Mer) either are not involved in these processes, or have highly spatio-temporally restricted roles, diminishing their significance as upstream inputs to Wts in follicle cells. This is further indicated in that Wts targets, CyclinE and DIAP1, are elevated in Fas2, dlg, lgl, wts, and roe cells, but not Fat, ex, or mer cells. Thus, the BLJ appears to regulate epithelial polarity and dynamics not only as a localized scaffold, but also by communicating signals to the nucleus. Wts may be regulated by distinct junction inputs depending on developmental context.
Early Intratracheal Instillation of Budesonide Using Surfactant as a Vehicle to Prevent Chronic Lung Disease in Preterm Infants: A Pilot Study
Authors: Yeh Tsu F. , Lin Hong C. , Chang Chien H. , Wu Tien S. , Su Bai H. , Li Tsai C. , Pyati Suma , Tsai Chang H.
Published: April 2008

OBJECTIVE. Budesonide is an inhaled steroid with a strong topical effect but with minimal systemic effects; it has been effectively delivered to animal lungs using surfactant as a vehicle. The purposes of this study were to determine whether early intratracheal instillation of budesonide using surfactant as a vehicle would improve pulmonary status, reduce mortality, and reduce chronic lung disease morbidity.

PATIENTS AND METHODS. We conducted a prospective, randomized blind trial in 116 very low birth weight infants (<1500 g) who had severe radiographic respiratory distress syndrome and required mechanical ventilation with fraction of inspired oxygen ≥0.6 shortly after birth: 60 were in the treated group (intratracheal instillation of a mixture of 0.25 mg/kg of budesonide and 100.00 mg/kg of survanta, every 8 hours) and 56 were in the control group (100 mg/kg of survanta only, every 8 hours). The end point assessment was the number of infants who would die or develop chronic lung disease at 36 weeks’ postconceptional age.

RESULTS. Infants in the treatment group required significantly lower mean airway pressure on day 1 and day 3 and had significantly lower oxygen index and Pco2 during the first 3 days than infants in the control group. More infants were extubated in the treatment group than controls at 1 and 2 weeks. The combined outcome of deaths or chronic lung disease was significantly lower in the treatment group than in the control group (19 of 60 vs 34 of 56). No clinically significant adverse effects were observed during the study.

CONCLUSIONS. This pilot study indicated that early postnatal intratracheal instillation of budesonide using surfactant as vehicle significantly improved the combined outcome of death or chronic lung disease in small premature infants without causing immediate adverse effects. The results are encouraging, and a large sample multicenter trial is warranted.
Predictors of Retinochoroiditis in Children With Congenital Toxoplasmosis: European, Prospective Cohort Study
Authors: Freeman Katherine , Tan Hooi Kuan , Prusa Andrea , Petersen Eskild , Buffolano Wilma , Malm Gunilla , Cortina-Borja Mario , Gilbert Ruth ,   for the European Multicentre Study on Congenital Toxoplasmosis
Published: April 2008

OBJECTIVE. By school age, 20% of children infected with congenital toxoplasmosis will have ≥1 retinochoroidal lesion. We determined which children are most at risk and whether prenatal treatment reduces the risk of retinochoroiditis to help clinicians decide about treatment and follow-up.

PATIENTS AND METHODS. We prospectively studied a cohort of children with congenital toxoplasmosis identified by prenatal or neonatal screening in 6 European countries. We determined the effects of prenatal treatment and prognostic markers soon after birth on the age at first detection of retinochoroiditis.

RESULTS. Of 281 children with congenital toxoplasmosis, 50 developed ocular disease, and 17 had recurrent retinochoroiditis during a median follow-up of 4.1 years. Prenatal treatment had no significant effect on the age at first or subsequent lesions. Delayed start of postnatal treatment did not increase retinochoroiditis, but the analysis lacked power. Older gestational age at maternal seroconversion was weakly associated with a reduced risk of retinochoroiditis. The presence of nonocular clinical manifestations of congenital toxoplasmosis at birth strongly predicted retinochoroiditis. For 92% (230 of 249) of children with no retinochoroiditis detected before 4 months of age, the probability of retinochoroiditis by 4 years was low, whether clinical manifestations were present or not 8.0%.

CONCLUSIONS. Prenatal treatment did not significantly reduce the risk of retinochoroiditis in this European cohort. If children have no retinochoroiditis in early infancy, the low risk of subsequent ocular disease may not justify postnatal treatment and repeated ophthalmic assessments during childhood. Controlled trials are needed to address the lack of evidence for the effectiveness of postnatal treatment.
Successful Drilling in Highly Depleted Formations
Authors: Ríos J. J. Alfredo , Luis Ángel Ayala G. , Casiano R. Rayón
Published: April 2008

The development of some reservoirs in the South Region of México was limited by highly depleted and/or naturally fractured formations that would not allow to reach the original geological goals. Those are Cretaceous and Jurassic period formations in carbonated rocks mainly limestone and dolomite. Oil well drilling under unbalanced pressure conditions demands special techniques for hydrodynamic control and hole stabilization in order to recover formation cuttings in the surface as well as to keep navigation control during drilling and gather indirect information of geophysical logs, as well as cutting and recovering cores and minimizing productive formations damage.

Analysis formations and non conventional drilling correspond to the reservoirs named Agave, Samaria, Iride and Jujo, in which successful drilling was performed using underbalanced drilling techniques, negative pulse navigation equipment, cutting and recovering of preserved core and particularly the development and application of low density foam fluid, designed and patented by PEMEX staff workers.

The main purpose of this paper is to illustrate the non conventional oil drilling techniques used to obtain successful results in highly depleted formations; with the attempt to make the application extensive to formations and reservoirs with similar subnormal pressures and/or naturally fractured.
Activation of Estrogen Receptor Is Crucial for Resveratrol-Stimulating Muscular Glucose Uptake via Both Insulin-Dependent and -Independent Pathways
Authors: Deng Jen-Ying , Hsieh Po-Shiuan , Huang Jiung-Pang , Lu Long-Sheng , Hung Li-Man
Published: April 2008

OBJECTIVE—Estradiol (E2) is known to modulate insulin sensitivity and, consequently, glucose homeostasis. Resveratrol (RSV), an agonist of estrogen receptor (ER), has exerted antihyperglycemic effects in streptozotocin-induced type 1 diabetic rats in our previous study and was also shown to improve insulin resistance in other reports. However, it remains unknown whether activation of ER is involved in the metabolic effects of RSV via insulin-dependent and -independent mechanisms.

RESEARCH DESIGN AND METHODS—Male Sprague-Dawley rats were given a high cholesterol–fructose (HCF) diet for 15 weeks and were treated with RSV for either 15 days or 15 weeks.

RESULTS—Here, we show that RSV shifts the metabolic characteristics of rats on an HCF diet toward those of rats on a standard diet. RSV treatment increased insulin-stimulated whole-body glucose uptake and steady-state glucose uptake of soleus muscle and liver in HCF-fed rats as well as enhanced membrane trafficking activity of GLUT4 and increased phosphorylation of insulin receptor in insulin-resistant soleus muscles. Interestingly, the phosphorylated ER level in insulin-resistant soleus muscle was significantly elevated in rats with RSV treatment in both basal and euglycemic-hyperinsulinemic conditions. RSV exerted an insulin-like stimulatory effect on isolated soleus muscle, epididymal fat and hepatic tissue, and C2C12 myotubes. The RSV-stimulated glucose uptake in C2C12 myotubes was dependent on extracellular signal–related kinase/p38 (early phase, 1 h) and p38/phosphoinositide 3-kinase (late phase, 14 h) activation. Inhibition of ER abrogated RSV-induced glucose uptake in both early and late phases.

CONCLUSIONS—Collectively, these results indicate that ER is a key regulator in RSV-stimulating insulin-dependent and -independent glucose uptake, which might account for the protective effects of RSV on diet-induced insulin resistance syndrome.
Haplotype Structure of the ENPP1 Gene and Nominal Association of the K121Q Missense Single Nucleotide Polymorphism With Glycemic Traits in the Framingham Heart Study
Authors: Stolerman Elliot S. , Manning Alisa K. , McAteer Jarred B. , Dupuis Josée , Fox Caroline S. , Cupples L. Adrienne , Meigs James B. , Florez Jose C.
Published: April 2008

OBJECTIVE—A recent meta-analysis demonstrated a nominal association of the ectonucleotide pyrophosphatase phosphodiesterase 1 (ENPP1) K→Q missense single nucleotide polymorphism (SNP) at position 121 with type 2 diabetes. We set out to confirm the association of ENPP1 K121Q with hyperglycemia, expand this association to insulin resistance traits, and determine whether the association stems from K121Q or another variant in linkage disequilibrium with it.

RESEARCH DESIGN AND METHODS—We characterized the haplotype structure of ENPP1 and selected 39 tag SNPs that captured 96% of common variation in the region (minor allele frequency ≥5%) with an r2 value ≥0.80. We genotyped the SNPs in 2,511 Framingham Heart Study participants and used age- and sex-adjusted linear mixed effects (LME) models to test for association with quantitative metabolic traits. We also examined whether interaction between K121Q and BMI affected glycemic trait levels.

RESULTS—The Q allele of K121Q (rs1044498) was associated with increased fasting plasma glucose (FPG), A1C, fasting insulin, and insulin resistance by homeostasis model assessment (HOMA-IR; all P = 0.01–0.006). Two noncoding SNPs (rs7775386 and rs7773477) demonstrated similar associations, but LME models indicated that their effects were not independent from K121Q. We found no association of K121Q with obesity, but interaction models suggested that the effect of the Q allele on FPG and HOMA-IR was stronger in those with a higher BMI (P = 0.008 and 0.01 for interaction, respectively).

CONCLUSIONS—The Q allele of ENPP1 K121Q is associated with hyperglycemia and insulin resistance in whites. We found an adiposity-SNP interaction, with a stronger association of K121Q with diabetes-related quantitative traits in people with a higher BMI.
Laser endotaxy in silicon carbide and PIN diode fabrication
Authors: Tian Z. , Quick N. R. , Kar A.
Published: April 2008

A laser solid phase diffusion technique has been utilized to fabricate endolayers in n-type 6H-SiC substrates by carbon incorporation. X-ray energy dispersive spectroscopic analysis shows that the thickness of the endolayer is about 100 nm. High resolution transmission electron microscopic images indicate that the laser endotaxy process maintains the crystalline integrity of the substrate without any amorphization. The resistivity of the endolayer formed in a 1.55 Ω cm silicon carbide wafer segment was found to be 1.1×105 Ω cm, which is sufficient for device fabrication and isolation. Annealing at 1000 °C for 10 min to remove hydrogen resulted in a resistivity of 9.4×104 Ω cm. The endolayer and parent silicon carbide epilayer were doped with aluminum using a laser doping technique to create p-regions on the top surfaces of the substrates in order to fabricate p-type-intrinsic type-n-type (PIN) diodes. The current-voltage characteristics of these diodes were compared with other PIN diodes fabricated using epilayers and other doping techniques.
In vivo and in vitro evaluation of the corneal damage induced by 1573 nm laser radiation
Authors: Courant Daniel , Chapel Catherine , Billy Céline , Salès Nicole , Pérot Jean-Claude , Pothier Christophe
Published: April 2008

This study involved the corneal effects of the laser beam in infrared at 1573 nm. Investigations were directed toward verifying the limit values by defining the thresholds of corneal damage in experiments carried out on the rabbit, and using biochemical techniques, to specify a damage threshold at the cellular level and a better understanding of the cellular steps of the damaging process. Corneal damage thresholds were determined for exposures to 3 ns single pulses using clinical observations and histology. The ED50 obtained with a corneal beam diameter of 400 μm was 26.6 J cm−2. The corresponding radiant exposure, calculated with the 1 mm aperture diameter recommended by standards, was 4.3 J cm−2. This value was still higher than the present 1 J cm−2 exposure limit. In vitro experiments were also carried out on primary keratocytes and HT1080 epithelial cell line. An expanded beam diameter of 3.5 mm was delivered on plates for study of cell proliferation, senescence, and cytotoxicity. The laser beam was expanded to 6 mm on chamber slide systems used for morphological analysis and apoptosis detection. Cells were irradiated with a pulse duration of 3 ns, a repetition rate of 10 Hz, a radiant exposure of 0.395 J cm−2 per pulse on plate, and 0.131 J cm−2 per pulse on chamber slide systems. A number of pulses varying from 13 to 40 on plates, and varying from 10 to 90 on chamber slide systems, led to total doses of 5.1 to 15.9 J cm−2 and 3.9 to 11.8 J cm−2, respectively. The frequency of apoptotic bodies seemed the most suitable criterion capable of revealing the cellular stress induced by laser radiation. The threshold for the appearance of apoptotic bodies in chamber slide systems was the total dose of 3.9 J cm−2.
Laser bioeffects associated with ultrafast lasers: Role of multiphoton absorption
Authors: Glickman Randolph D. , Johnson Thomas E. , Noojin Gary D. , Stolarski David J. , Denton Michael L. , Kumar Neeru , Rockwell Benjamin A.
Published: April 2008

Although laser-induced breakdown has the lowest energy threshold in the femtosecond domain, and appears to be responsible for production of threshold retinal lesions by ultrashort pulse lasers, previous findings suggested a role for multiphoton absorption in retinal damage. In this study, we investigated if near infrared ultrashort laser pulses produced DNA damage by exciting short wavelength-absorbing chromophores via multiphoton absorption. The experiments were carried out in nonpigmented and artificially pigmented hTERT-RPE cells, a line of human-derived retinal pigment epithelial (RPE) cells. Cells were exposed to 0.25 s pulses of CW and mode-locked 810 nm laser emissions, at irradiances equivalent to 0.5 and 1.0 times the ED50 for threshold damage in the primate eye, and DNA strand breaks were measured using the comet assay (single cell gel electrophoresis). At 0.5 X ED50, increased DNA strand breakage occurred after the ultrashort (mode-locked) exposures, but not the CW exposures, compared to control cells. At 1.0 X ED50, both the mode-locked- and CW-exposed cells exhibited increased DNA damage, compared to controls. These differences, although significant, were inconsistent, because they were found only in the comet assay tail length parameter, but not the tail moment parameter. Moreover, the amount of DNA strand breakage was clearly dependent on the amount of melanin pigmentation in the cells, regardless of laser pulsewidth. A theoretical analysis found that the number of photons delivered to the RPE melanosome during a single 33–250 fs pulse, at an irradiance equivalent to the ED50, was insufficient to produce multiphoton excitation. In addition, the equivalent DNA strand breakage in pigmented RPE cells after ultrashort and CW exposures indicated that multiphoton absorption is not a major contributor to the ultrashort pulse laser damage threshold in the near infrared optical spectrum.
Connection of macro-sized double-walled carbon nanotube strands by current-assisted laser irradiation
Authors: Gong Tao , Zhang Yong , Liu Wenjin , Wei Jinquan , Wang Kunlin , Wu Dehai , Zhong Minlin
Published: April 2008

Macro-sized (centimeters long) double-walled carbon nanotube (DWNT) strands were connected by current-assisted laser irradiation after bandaging their overlapped ends with DWNT films. During the laser processing, structural transformation of DWNT bundles happened at the joints, which provided molecular bonding between the strands. Tensile tests indicate that the joints made in this way have relatively high tensile strength with a maximum value of 335.6 MPa corresponding to that of the original strands. And the electronic properties of the connected strands were not greatly weakened in our investigation on their temperature dependence of resistivity. This work may offer a promising potential for future extensive use of macro-sized carbon nanotube structures in many fields.
Design and validation of a hybrid laser/water-jet machining system for brittle materials
Authors: Kalyanasundaram Dinesh , Shehata Gamal , Neumann Clayton , Shrotriya Pranav , Molian Pal
Published: April 2008

A unique laser/water-jet (LWJ) cutting head has been designed, built, and interfaced with a CO2 laser for cutting and scribing of hard and brittle ceramic materials. Alumina samples were used to validate the effectiveness of the LWJ cutting head in thermal fracture mode. The results were compared with vaporization mode (focused beam) as well as thermal fracture mode (defocused beam) of air-assisted laser cutting. The thermal fracture mode in both LWJ and air-assisted laser cutting required three to five times less energy input for material separation than the vaporization mode. However, the quality of the cut surfaces of the LWJ was superior to both vaporization and thermal fracture modes of air-assisted laser cutting in terms of kerf, recast zone, density of microcracks, undercutting, and spatter. The synergistic effects of laser and water-jet facilitated precise material separation and better cut quality through: thermal shock-induced fracture mode of material separation rather than energy-intensive erosive wear (water-jet alone) or melting and subsequent evaporation (laser alone); and expulsion of cracked material with kinetic energy associated with the water-jet, leaving a clean cut surface.
Influence of Temperature and Daylight Length on Barley Infection by Pyrenophora Teres
Authors: Kosiada Tomasz
Published: April 2008

Influence of Temperature and Daylight Length on Barley Infection byPyrenophora Teres

Net blotch caused byPyrenophora teresis the most important disease of barley in many regions in which this cereal is cultivated. In the performed work the influence of solarization period and temperature on infection of barley byP. tereswas estimated. Three isolates of eachP. teresf.teresandP. teresf.maculatawere used. The response of six barley genotypes to the pathogen was estimated. Barley infection was differentiated and depended on solarization period, and the isolate ofP. teres.Number of infected plants increased with the increase of temperature. Interaction occurred among length of solarization period and temperature. The highest barley infection byP. teresf.tereswas observed at 10 hours of solarization and temperature 25°C.
Occurrence of Bemisia Argentifolii on Chrysanthemums in Northern Tanzania
Authors: Ndomba Osmund
Published: April 2008

Occurrence ofBemisia Argentifoliion Chrysanthemums in Northern Tanzania

Samples of whiteflies were collected fromDendranthemaspp. in major growing areas of Tanzania. The insects were transferred onto test plants to confirm host specificity. Infested with insects, test plants were then protected with polyethylene bags. Samples of whiteflies from infested plants were taken at 10 day intervals post-infestation (dpi), 28 dpi and 35 dpi, for behavioural studies. At 10 dpi eggs were seen as oval bodies while at 28 dpi crawling bodies and newly emerged adults were observed, leaving behind characteristic shiny hollow cases. At 35 dpi, all the stages of development were seen. The features observed are typical ofBemisia argentifoliiand the area is endangered by the occurrence and spread of viruses transmitted by this species. This identification, which is an integral part of pest surveillance, initiates a study of the viruses and will lead to pest records for regulatory purposes. The international scientific and trading community is assured that the report reflects the real situation. The pest is thought to be present in the reported areas only and the pest status is actionable and under surveillance.
Pathogenicity of Meloidogyne Incognita on Sesamum Indicum and the Efficacy of Yield-Based Scheme in Resistance Designation
Authors: Atungwu Jonathan , Afolami Steve , Egunjobi Olufunke , Kadri Opeyemi
Published: April 2008

Pathogenicity ofMeloidogyne IncognitaonSesamum Indicumand the Efficacy of Yield-Based Scheme in Resistance Designation

Two screenhouse experiments were conducted in 2004 and 2005 rainy season to investigate the reaction of three selectedSesamum indicumcultivars against three population densities of a root knot nematode,Meloidogyne incognita.Seedlings ofS. indicumwere raised in pots arranged in completely randomised design and inoculated with 0, 5 000, and 10 000 eggs ofM. incognita, replicated six times. Root knot disease was evaluated at mid-season and harvest. A new method for evaluating and reporting resistance toMeloidogynespp. that divides the screening procedure into two phases in the same experiment was adapted. The first phase investigated the host response through the traditional standard method that utilises only gall and nematode reproduction indices, while the second considered the effect of root knot disease on grain production of the crop. There was consistency in host designation of E8 and NICRIBEN-01M (syn: 530-1-6) which were classified under the traditional and improved rating schemes as tolerant and resistant, respectively. However,S. indicumbreeding line Pbtil (No. 1) which was considered susceptible under the old system was found to be tolerant using the integrated and improved system. Root galls incited by the nematode degenerated significantly from mid-season to harvest time. Utilising yield as additional parameter for assessing resistance to root knot nematode provides a complete picture ofSesamum-Meloidogyneinteraction, and therefore a more meaningful system for determining host response.
Effect of Bt Maize Mon 810 Expressing Cry 1 Ab Toxin on Aphidius Colemani in Tritrophic Plant - Herbivore - Parasitoid System
Authors: Górecka Julia , Godzina Monika , Dąbrowski Zbigniew
Published: April 2008

Effect of Bt Maize Mon 810 Expressing Cry 1 Ab Toxin onAphidius Colemaniin Tritrophic Plant - Herbivore - Parasitoid System

Effect of Bt maize MON 810 expressing Cry 1 Ab toxin on braconidAphidius colemaniin tritrophic plant - herbivore - parasitoid system was studied under greenhouse conditions by rearing the bird cherry-oat aphid (Rhopalosiphum padi) on genetically modified maize cultivar DKc 307 (MON 810) and its isogenic parent cultivar - Monumental of Monsanto Ltd.R. padiaphids reached higher population level when maintained on Bt-maize cultivar DKc 307 (MON 810) than on its isogenic parent cultivar - Monumental both in the winter and summer experiments. The braconidA. colemanideveloped higher population onR. padiaphid population feeding on Bt maize plants in the summer experiment and on non-Bt plants in the winter experiment. The observed effect of season on parasitation level byA. colemanionR. padihost feeding on Bt and non-Bt maize plants indicates that results obtained in a single greenhouse experiment may lead to questionable conclusions and should be confirmed by other experiments.
Book Review Horst R. K., Cloyd R. A. 2007. Compendium of Rose Diseases and Pests. Second Edition. APS Press - The American Phytopathological Society, St. Paul, Minnesota, USA. 83 pp. ISBN 978-0-89054-355-9.
Authors: Lipa Jerzy
Published: April 2008

Book Review Horst R. K., Cloyd R. A. 2007. Compendium of Rose Diseases and Pests. Second Edition. APS Press - The American Phytopathological Society, St. Paul, Minnesota, USA. 83 pp. ISBN 978-0-89054-355-9.
Development of a 500-Hz Masking-Level Difference Protocol for Clinic Use
Authors: Wilson Richard H. , Moncrieff Deborah W. , Townsend Elizabeth A. , Pillion Amanda L.
Published: April 2008

The purpose of this series of experiments was to develop a simple, 500-Hz masking-level difference (MLD) protocol that could be implemented easily in the clinic to assess auditory perceptual abilities using an audio compact disc. Five, 300-ms tones with 250-ms intertone intervals were
embedded in 3-s bursts of 200-800 Hz noise presented at 42.2-dB pressure-spectrum level with 4-5 s inter-stimulus intervals. The homophasic and antiphasic conditions were interleaved with the signal-to-noise ratios decreasing in 2-dB steps. A single-interval, "yes/no" response task
was used. Three experiments were performed on 24-28 listeners with normal hearing. The mean SoNo thresholds (58.1- to 59.5-dB SPL) and the mean SπNo thresholds (45.1- to 46.0-dB SPL) produced ∼13-dB MLDs. Experiment 3 included a SoNπ condition that had a mean threshold of 48.8-dB
SPL and a 10.0-dB MLD. The mean test, retest ot the SoNo and SπNo thresholds on 15 listeners was <0.5 dB. Over the three experiments, 95% of the listeners had SπNo MLDs that were ≥10 dB. El propósito de esta serie de experimentos fue el desarrollo de un protocolo simple
utilizando el nivel diferencial del enmascaramiento (MLD) a 500 Hz, que pudiera ser implementado con facilidad en la clínica para la evaluación de las habilidades perceptuales auditivas utilizando un disco compacto de audio. Se incorporaron cinco tonos de 300 ms con intervalos
intertono de 250 ms en medio de bursts tonales de 3 segundos con ruido de 200 a 800 Hz, presentados a 42.2 dB de nivel espectral de presión, con intervalos interestímulo de 4 a 5 segundos. Las condiciones homofásicas y antifásicas se intercalaron con las tasas señal/ruido,
disminuyendo en pasos de 2 dB. Se utilizó una tarea de respuesta "si/no" de intervalo único. Se realizaron tres experimentos en 24 a 28 sujetos con audición normal. Los umbrales SoNo medios (58.1 a 59.5 dB SPL) Y los umbrales SπNo medios (45.1 a 46 dB SPL)
produjeron un MLD de 13 dB. El experimento 3 incluyó una condición SoNπ que muestra un umbral medio de 48.8 dB SPL y un MLD de 10.0 dB. El resultado medio del test/retest para los umbrales SoNo y SπNo en 15 sujetos fue de < 0.5 dB. En los 3 experimentos, 95% de los sujetos
tuvieron un MLD para SπNo menor o igual a 10 dB.
Predictive Validity and Reliability of Adult Hearing Screening Techniques
Authors: Scudder Sharon G. , Culbertson Deborah S. , Waldron Claire M. , Stewart Jill
Published: April 2008

The purpose of this study was to evaluate and compare the efficacy of hearing screening tools to identify hearing loss in the older adult population. The test-retest reliability of both the AuDX DPOAE hand-held screener and subjective otoscopic ratings of percent earwax accumulation
were evaluated. Additionally, the predictive validity was investigated for five hearing screening tools: the DPOAE hand-held screener, pure-tone screening, screening otoscopy, self-assessment of communication, and case history screening. The research was conducted through typical community
hearing screenings on normal-hearing and hearing-impaired volunteer subjects. The screening subjects included 67 adults aged 49 to 89 years. Of those, 44 returned for a full audiologic evaluation. Key findings include: (1) Pure-tone screening had predictive validity for actual hearing loss
in the older adult population when a 25 dB HL fence is used; (2) Screening otoscopy ratings were highly reliable across time and raters; (3) Self-assessment scores did not predict compliance with referral recommendations; (4) The AuDX DPOAE hand-held screener proved to be reliable in the overall
pass/refer outcome, but lacked predictive validity for actual hearing loss in older adults. El propósito de este estudio fue evaluar y comparar la eficacia de herramientas de identificación auditiva por tamizaje (screening) en la población de adultos mayores. Se
evaluó la confiabilidad en la evaluación/re-evaluación utilizando la unidad manual AuDX de emisiones otoacústicas por productos de distorsión (DPOAE) y las estimaciones otoscópicas subjetivas de la acumulación percentual de cerumen. Además,
se evaluó la validez predictiva de otras cinco herramientas de tamizaje: la unidad manual de DPOAE, el tamizaje por tonos puros, el tamizaje por otoscopía, la auto-evaluación de la comunicación y el tamizaje por historia clinica. La investigación fue conducida
por medio de procedimientos típicos de identificación auditiva en la comunidad, con sujetos voluntarios normo-oyentes y con hipoacusia. La población evaluada incluyó 67 adultos con edades entre 49 y 89 años. De ellos, 44 acudieron para recibir una evaluación
audiológica completa. Los hallazgos claves fueron: (1) el tamizaje con tonos puros tuvo validez predictiva para hipoacusia en la población adulta mayor cuando se utilizó un límite inferior de 25 dB HL; (2) las apreciaciones de tamizaje por otoscopía fueron
altamente confiables en el tiempo y con los diferentes evaluadores; (3) los puntajes de auto-evaluación no predijeron cumplimiento de la recomendaciones de referencia; y (4) la unidad manual AuDX DPOAE probó ser confiable en el resultado global de pasa/falla, pero no tuvo validez
predictiva para hipoacusia en los adultos mayores.
High-Frequency (1000 Hz) Tympanometry in Normal Neonates
Authors: Kei Joseph , Allison-Levick Julie , Dockray Jacqueline , Harrys Rachel , Kirkegard Christina , Wong Janet , Maurer Marion , Hegarty Jayne , Young June , Tudehope David
Published: April 2008

The characteristics of high frequency (1000 Hz) acoustic admittance results obtained from normal neonates were described in this study. Participants were 170 healthy neonates (96 boys and 74 girls) aged between 1 and 6 days (mean = 3.26 days, SD = 0.92). Transient evoked otoacoustic
emissions (TEOAEs), and 226 Hz and 1000 Hz probe tone tympanograms were obtained from the participants using a Madsen Capella OAE/middle ear analyser. The results showed that of the 170 neonates, 34 were not successfully tested in both ears, 14 failed the TEOAE screen in one or both ears,
and 122 (70 boys, 52 girls) passed the TEOAE screen in both ears and also maintained an acceptable probe seal during tympanometry. The 1000 Hz tympanometric data for the 122 neonates (244 ears) showed a single-peaked tympanogram in 225 ears (92.2 %), a flat-sloping tympanogram in 14 ears (5.7
%), a double-peaked tympanogram in 3 ears (1.2 %) and other unusual shapes in 2 ears (0.8 %). There was a significant ear effect, with right ears showing significantly higher mean peak compensated static admittance and tympanometric width, but lower mean acoustic admittance at +200 daPa and
gradient than left ears. No significant gender effects or its interaction with ear were found. The normative tympanometric data derived from this cohort may serve as a guide for detecting middle ear dysfunction in neonates. El estudio describe las caracterrsticas de la admitancia acústica
de alta frecuencia (1000 Hz) obtenida en neonatos normales. Los participantes fueron 170 neonatos saludables (26 niños y 74 niñas) con edades entre 1 y 6 días (media de 3.26, SD = 0.92). Se obtuvieron emisiones otoacústicas evocadas por transientes (TEOAE) y timpanogramas
realizados con una sonda de prueba de 226 Hz y 1000 Hz usando una unidad Madsen Capella con un analizador de oído medio y EOA. Los resultados mostraron que de los 170 neonatos, 34 no pudieron ser evaluados en ambos oídos, 14 fallaron la prueba de TEOAE en uno o en ambos oídos,
y 122 (70 niños y 52 niñas) pasaron el tamizaje de TEOAE en ambos oídos y también mantuvieron un nivel de sello aceptable en la sonda de timpanometría. La información timpanométrica a 1000 Hz para los 122 neonatos (244 oídos) mostró
un timpanograma de pico único en 225 oídos (32.2%), un timpanograma plano con pendiente en 14 oídos (5.7%), un timpanograma de doble pico en 3 ordos (1.2%), y otras forma inusuales en 2 ordos (0.8%). Existió un significativo efecto de oído, con los oídos
derechos mostrando picos medios compensados de admitancia estática y anchos timpanométricos significativamente mayores, aunque gradientes y admitancias acústica promedio menores a + 200 daPa, en oídos izquierdos. No se encontró un significativo efecto de
género o de género por oído. La información normativa timpanométrica de esta cohorte puede servir como una guí a para detectar disfunción de oído medio en neonatos.
Should Significant Others Be Encouraged to Join Adult Group Audiologic Rehabilitation Classes?
Authors: Preminger Jill E.
Published: April 2008

The benefit of participation in group audiologic rehabilitation classes was examined for adults with hearing loss (subjects) and their significant others (SOs). Thirteen subjects attended the classes with their SOs, and 12 subjects attended the classes on their own. All subjects attended
six 90-minute classes consisting of informational lectures, and training in communication strategies, auditory perception, and auditory and visual perception. Self-assessment scales measuring hearing aid benefit and use of communication strategies were completed prior to class participation
and following the completion of all classes. The results indicated that the majority of subjects reported increased use of communication strategies following class participation. In addition, a significant reduction in hearing handicap following class participation was measured across all
subjects and SOs, and the greatest reduction in handicap was measured for subjects who attended the classes with their SOs. SO participation in group AR (audiologic rehabilitation) classes should be encouraged. Se examinó el beneficio de la participación de adultos con hipoacusia
(sujeto) y de la "persona significativa" para ellos (Significant other: SO), en sesiones de rehabilitación audiológica grupal. Trece sujetos asistieron a dichas sesiones con sus "SO" y doce lo hicieron solos. Todos los sujetos asistieron a seis sesiones de
90 minutos que incluían conferencias de información, y un entrenamiento en estrategias de comunicación, en percepción auditiva y en percepción auditiva y visual. Se completaron escalas de auto-evaluación que medían el beneficio de los auxiliares
auditivos y el uso de estrategias de comunicación, antes de participar en estas sesiones y después de completar todo el proceso. Los resultados indican que la mayoría de los sujetos reportaron un incremento en el uso de las estrategias de comunicación a partir de
su participación en estas sesiones. Además, se detectó una reducción significativa en la desventaja auditiva luego de dicha participación, en todos los sujetos y sus "SO", y la mayor reducción en la desventaja se obtuvo en aquellos sujetos
que asistieron acompañados de su "persona significativa". La participación de las "personas significativas" para el paciente, en las sesiones de RA grupal (rehabilitación audiológica) debería ser estimulada.
The Effects of Frequency Response on Speech Perception for Cochlear Implant Users
Authors: Weatherby Alexandra , Henshall Katherine R. , McKay Colette M.
Published: April 2008

The aim of this study was to investigate the effects on speech perception of manipulating filter gains in a cochlear implant speech processor. Five implantees, who use the CI22 implant and Spectra processor manufactured by Cochlear Ltd, participated. Four experimental maps were created
that were identical to their clinical map except for the profile of gains across the filters. Experimental gain profiles had rising or falling gains across the frequency range, or emphasized or de-emphasized the middle frequencies, relative to the clinical map. Perception of CNC (consonant-vowel-consonant)
words at 70 dB SPL was significantly better with the clinical map than with all experimental maps, whereas at the lower level (60 dB SPL) there was minimal difference between the maps, with the low-frequency emphasis map giving significantly better scores than the high-frequency emphasis map.
Perception of sentences at 70 dB SPL with a signal-to-noise ratio of +10 dB was better with the high-frequency emphasis map than with the low-frequency emphasis map. None of these best-conditions, however, were statistically better than the clinical map. The results highlighted the importance
of signal audibility for speech perception with cochlear implants. El propósito de este estudio fue investigar los efectos sobre la percepción del lenguaje de la manipulación de los filtros de ganancia en el procesador de lenguaje de un implante coclear. Participaron cinco
implantados con un implante CI22 y el procesador Spectra fabricado por Cochlear Ltda. Se crearon cuatro mapas experimentales que eran idénticos al mapa clínico excepto por el perfil de ganancias en los diferentes filtros. Los perfiles de ganancia experimental tenían ganancias
ascendentes o descendentes en todo el rango de frecuencias, o enfatizaban o des-enfatizaban las frecuencias medias, con relación al mapa clínico. La percepción de las palabras CNC (consonante-vocal-consonante) a 70 dB SPL fue significativamente mejor con el mapa clínico
que con todos los mapas experimentales, mientras que al nivel inferior (60 dB SPL) existió una diferencia mínima entre los distintos mapas, donde el mapa con énfasis en las frecuencias graves obtuvo puntajes significativamente mejores que el mapa con énfasis en
las frecuencias agudas. La percepción de frases a 70 dB SPL, con una tasa de señal/ruido de + 10 dB, fue mejor con el mapa con énfasis en las frecuencias agudas que con el mapa de énfasis en las frecuencias graves. Ninguna de estas condiciones óptimas, sin
embargo, fue significativamente mejor que con el mapa clínico. Los resultados destacaron la importancia de la audibilidad de la señal para la percepción del lenguaje con implantes cocleares.
The Effects of Probe-Tone Frequency on the Acoustic-Reflex Growth Function
Authors: Lutolf John J. , O'Malley Honor , Silman Shlomo
Published: April 2008

Acoustic-reflex growth functions (ARGFs) were obtained from 20 normal-hearing listeners, Contralateral acoustic reflexes (ARs) were elicited with pure tones of 2000 Hz. The magnitude of changes in static compliant susceptance (BA) and conductance (GA) were monitored with probe-tone
frequencies of 226 Hz, 678 Hz and 1000 Hz. ARGFs were obtained with six combinations of probe-tone frequency/admittance component: 226 Hz BA, 226 Hz GA, 678 Hz BA, 678 Hz GA, 1000 Hz BA, and 1000 Hz GA. Peak conductance (GA) and susceptance (BA) ARs were largest within the 678 Hz GA and 1000
Hz BAARGFs, respectively. Among high-frequency probe tones, the patterns of AR growth were larger and less variable for the 678 Hz GA ARGF and the 1000 Hz BA ARGF as determined by the magnitude of their linear (b1) and quadratic (b2) polynomial coefficients and the value of their squared correlation
coefficients (R2). Se obtuvieron funciones de crecimiento del reflejo acústico (ARGFs) de 20 sujetos con audición normal. Se generaron reflejos acústicos contralaterales (ARs) con tonos puros a 2000 Hz. La magnitud de los cambios en la compliancia de susceptancia estática
(BA) y en la conductancia (GA) se monitorizaron con sondas de prueba a frecuencias de 226 Hz, 678 Hz y 1000 Hz. Los ARGF se obtuvieron con seis combinaciones del componente constituido por la frecuencia de la sonda de prueba y la admitancia: 226 Hz BA, 226 Hz GA, 678 Hz BA, 678 Hz GA, 1000
Hz BA y 1000 Hz GA. Los AR obtenidos a conductancia (GA) y susceptancia (BA) pico fueron los mayores dentro de las ARGF a 678 Hz GA y 1000 Hz BA, respectivamente. Entre los tonos de prueba de alta frecuencia, los patrones de crecimiento del AR fueron mayores y menos variables para los ARGF
a 678 Hz GA y los ARGF a 1000 Hz BA, determinados por la magnitud de sus coeficientes de polinomio lineal (b1) y de polinomio cuadrático, y por el valor de sus coeficientes de correlación al cuadrado (R2).
Acoustic Hemifields in the Spatial Release from Masking of Speech by Noise
Authors: Phillips D.P. , Vigneault-MacLean B.K. , Boehnke S.E. , Hall S.E.
Published: April 2008

The Hearing-in-Noise Test (HINT) is able to measure the benefit to speech intelligibility in noise conferred when the noise masker is displaced 90 degrees in eccentricity from a speech source located at zero degrees azimuth. Both psychoacoustic and neurophysiological data suggest that
the perceptual benefit of the 90-degree azimuth separation would be greatest if the speech and noise were presented in different acoustic hemifields, and would be smallest if the two sources were in the same acoustic hemifield. The present study tested this hypothesis directly in ten normal-hearing
adult listeners. Using the HINT stimuli, we confirmed the hypothesis. Release from masking scores averaged 8.61 dB for "between-hemifield" conditions, 6.05 dB for HINT conditions, and 1.27 dB for "within-hemifield" conditions, even though all stimulus configurations retained
a 90-degree angular separation of speech and noise. These data indicate that absolute separation of speech and noise alone is insufficient to guarantee a significant release from masking, and they suggest that what matters is the location of the stimulus elements relative to the left and right
spatial perceptual channels. La Prueba de Audición en Ruido (HINT) permite medir los beneficios para la inteligibilidad del lenguaje en ruido que ocurre cuando el enmascarador de ruido es desplazado 90 grados de la fuente de lenguaje localizada a 0 grados azimut. Tanto los datos psicoacústicos
como neurofisiológicos sugieren que el beneficio perceptual de la separación de 90 grados azimut sería mayor si el lenguaje y el ruido fueran presentados en diferentes hemicampos acústicos, y sería menor si las dos fuentes estuvieran en el mismo hemicampo.
El presente estudio evaluó esta hipótesis directamente en diez sujetos adultos normo-oyentes. Utilizando los estímulos del HINT, confirmamos la hipótesis. Los puntajes de liberación del enmascaramiento promediaron 8.61 dB para las condiciones de "entre-hemicampos".
6.05 dB para las condiciones del HINT, y 1.27 para las condiciones "dentro del hemicampo", a pesar de que la configuración de todos los estímulos retuvo una separación angular de 90 grados entre el lenguaje y el ruido. Estos datos indican que la separación
absoluta del ruido y lenguaje solos es insuficiente para garantizar una liberación significativa del enmascaramiento, y sugieren que lo que importa es la localización de los elementos del estímulo con relación a los canales perceptuales espaciales derecho e izquierdo.
Masking Redux II: A Recommended Masking Protocol
Authors: Turner Robert G.
Published: April 2008

This is the second in a series of two papers on masking. The objective of these papers is to develop a masking protocol that provides valid measures of threshold and is, in general, faster than the plateau method. In the first paper, a masking method was presented that can replace the
traditional plateau method in most masking situations. This new method is optimized to require fewer masking levels than the plateau method. As a result, this optimized method is faster, sometimes significantly, than the plateau method. This paper evaluates the optimized method and compares
the optimized method to the traditional plateau method. This paper identifies specific masking situations in which the optimized method is not appropriate. A variation on the plateau method is described. When combined with the optimized method, these two masking methods constitute a recommended
masking protocol that can be used in all masking situations. Este es el segundo de una serie de dos trabajos relacionados con el enmascaramiento. El objetivo de estos trabajos es desarrollar un protocolo de enmascaramiento que proporcione mediciones válidas del umbral y que sea, en
general, más rápido que el método del plateau. En el primer trabajo, se presentó un método de enmascaramiento que puede reemplazar al método tradicional del plateau en la mayor parte de las situaciones que lo requieren. Este nuevo método ha
sido optimizado para necesitar menos niveles de enmascaramiento que el método del plateau. Como resultado, este método es significativamente más rápido que el tradicional. Este trabajo evalúa el método optimizado y lo compara con el método del
plateau. El trabajo identifica situaciones específicas de enmascaramiento en las que el método optimizado no es apropiado. Se describe una variante del método del plateau. Cuando se combinan con el método optimizado, estos dos métodos constituyen el protocolo
recomendado de enmascaramiento, que puede ser utilizado en todas las situaciones que demandan enmascaramiento.