Modulation of respiratory responses to chemoreflex activation by L-glutamate and ATP in the rostral ventrolateral medulla of awake rats

Moraes DJA, Bonagamba LGH, Zoccal DB, Machado BH. Modulation of respiratory responses to chemoreflex activation by L-glutamate and ATP in the rostral ventrolateral medulla of awake rats. Am J Physiol Regul Integr Comp Physiol 300: R1476-R1486, 2011. First published March 16, 2011; doi:10.1152/ajpregu.00825.2010.-Presympathetic neurons in the different anteroposterior aspects of rostral ventrolateral medulla (RVLM) are colocalized with expiratory [Botzinger complex (BotC)] and inspiratory [pre-Botzinger complex (pre-BotC)] neurons of ventral respiratory column (VRC), suggesting that this region integrates the cardiovascular and respiratory chemoreflex responses. In the present study, we evaluated in different anteroposterior aspects of RVLM of awake rats the role of ionotropic glutamate and purinergic receptors on cardiorespiratory responses to chemoreflex activation. The bilateral ionotropic glutamate receptors antagonism with kynurenic acid (KYN) (8 nmol/50 nl) in the rostral aspect of RVLM (RVLM/BotC) enhanced the tachypneic (120 +/- 9 vs. 180 +/- 9 cpm; P < 0.01) and attenuated the pressor response (55 +/- 2 vs. 15 +/- 1 mmHg; P < 0.001) to chemoreflex activation (n = 7). On the other hand, bilateral microinjection of KYN into the caudal aspect of RVLM (RVLM/pre-BotC) caused a respiratory arrest in four awake rats used in the present study. Bilateral P2X receptors antagonism with PPADS (0.25 nmol/50 nl) in the RVLM/BotC reduced chemoreflex tachypneic response (127 +/- 6 vs. 70 +/- 5 cpm; P < 0.001; n = 6), but did not change the chemoreflex pressor response. In addition, PPADS into the RVLM/BtC attenuated the enhancement of the tachypneic response to chemoreflex activation elicited by previous microinjections of KYN into the same subregion (188 +/- 2 vs. 157 +/- 3 cpm; P < 0.05; n = 5). Our findings indicate that: 1) L-glutamate, but not ATP, in the RVLM/BtC is required for pressor response to peripheral chemoreflex and 2) both transmitters in the RVLM/BtC are required for the processing of the ventilatory response to peripheral chemoreflex activation in awake rats.

Quantitative three-dimensional power Doppler angiography: a flow-free phantom experiment to evaluate the relationship between color gain, depth and signal artifact

Objectives To evaluate the presence of false flow three-dimensional (3D) power Doppler signals in `flow-free` models. Methods 3D power Doppler datasets were acquired from three different flow-free phantoms (muscle, air and water) with two different transducers and Virtual Organ Computer-aided AnaLysis was used to generate a sphere that was serially applied through the 3D dataset. The vascularization flow index was used to compare artifactual signals at different depths (from 0 to 6 cm) within the different phantoms and at different gain and pulse repetition frequency (PR F) settings. Results Artifactual Doppler signals were seen in all phantoms despite these being flow-free. The pattern was very similar and the degree of artifact appeared to be dependent on the gain and distance from the transducer. False signals were more evident in the far field and increased as the gain was increased, with false signals first appearing with a gain of 1 dB in the air and muscle phantoms. False signals were seen at a lower gain with the water phantom (-15 dB) and these were associated with vertical lines of Doppler artifact that were related to PRF, and disappeared when reflections were attenuated. Conclusions Artifactual Doppler signals are seen in flow-free phantoms and are related to the gain settings and the distance from the transducer. In the in-vivo situation, the lowest gain settings that allow the detection of blood flow and adequate definition of vessel architecture should be used, which invariably means using a setting near or below the middle of the range available. Additionally, observers should be aware of vertical lines when evaluating cystic or liquid-containing structures. Copyright (C) 2010 ISUOC. Published by John Wiley & Sons, Ltd.

Assessment of two central auditory tests in elderly patients without hearing complaints

Speech understanding disorders in the elderly may be due to peripheral or central auditory dysfunctions. Asymmetry of results in dichotic testing increases with age, and may reflect on a lack of inter-hemisphere transmission and cognitive decline. Aim: To investigate auditory processing of aged people with no hearing complaints. Study design: clinical prospective. Materials and Methods: Twenty-two voluntary individuals, aged between 55 and 75 years, were evaluated. They reported no hearing complaints and had maximal auditory thresholds of 40 dB HL until 4 KHz, 80% of minimal speech recognition scores and peripheral symmetry between the ears. We used two kinds of tests: speech in noise and dichotic alternated dissyllables (SSW). Results were compared between males and females, right and left ears and between age groups. Results: There were no significant differences between genders, in both tests. Their Left ears showed worse results, in the competitive condition of SSW. Individuals aged 65 or older had poorer performances than those aged 55 to 64. Conclusion: Central auditory tests showed worse performance with aging. The employment of a dichotic test in the auditory evaluation setting in the elderly may help in the early identification of degenerative processes, which are common among these patients.

Effect of diabetes on orthodontic tooth movement in a mouse model

Orthodontic tooth movement is achieved by the remodeling of alveolar bone in response to mechanical loading. Type 1 diabetes results in bone remodeling, suggesting that this disease might affect orthodontic tooth movement. The present study investigated the effects of the diabetic state on orthodontic tooth movement. An orthodontic appliance was placed in normoglycemic (NG), streptozotocin-induced diabetes (DB), and insulin-treated DB (IT) C57BL6/J mice. Histomorphometric analysis and quantitative PCR of periodontium were performed. The DB mice exhibited greater orthodontic tooth movement and had a higher number of tartrate-resistant acid phosphate (TRAP) -positive osteoclasts than NG mice. This was associated with increased expression of factors involved in osteoclast activity and recruitment (Rankl, Csf1, Ccl2, Ccl5, and Tnfa) in DB mice. The expression of osteoblastic markers (Runx2, Ocn, Col1, and Alp) was decreased in DB mice. Reversal of the diabetic state by insulin treatment resulted in morphological findings similar to those of NG mice. These results suggest that the diabetic state up-regulates osteoclast migration and activity and down-regulates osteoblast differentiation, resulting in greater orthodontic tooth movement.

Speech intelligibility with and without noise in individuals exposed to electronic music

Audiometry is the main way with which hearing is evaluated, because it is a universal and standardized test. Speech tests are difficult to standardize due to the variables involved, their performance in the presence of competitive noise is of great importance. Aim: To characterize speech intelligibility in silence and in competitive noise from individuals exposed to electronically amplified music. Material and Method: It was performed with 20 university students who presented normal hearing thresholds. The speech recognition rate (SRR) was performed after fourteen hours of sound rest after the exposure to electronically amplified music and once again after sound rest, being studied in three stages: without competitive noise, in the presence of Babble-type competitive noise, in monotic listening, in signal/ noise ratio of + 5 dB and with the signal/ noise ratio of 5 dB. Results: There was greater damage in the SRR after exposure to the music and with competitive noise, and as the signal/ noise ratio decreases, the performance of individuals in the test also decreased. Conclusion: The inclusion of competitive noise in the speech tests in the audiological routine is important, because it represents the real disadvantage experienced by individuals in daily listening.

Outcomes of transient evoked otoacoustic emission testing in 6-year-old school children: A comparison with pure tone screening and tympanometry

Objectives: (1) To establish test performance measures for Transient Evoked Otoacoustic Emission testing of 6-year-old children in a school setting; (2) To investigate whether Transient Evoked Otoacoustic Emission testing provides a more accurate and effective alternative to a pure tone screening plus tympanometry protocol. Methods: Pure tone screening, tympanometry and transient evoked otoacoustic emission data were collected from 940 subjects (1880 ears), with a mean age of 6.2 years. Subjects were tested in non-sound-treated rooms within 22 schools. Receiver operating characteristics curves along with specificity, sensitivity, accuracy and efficiency values were determined for a variety of transient evoked otoacoustic emission/pure tone screening/tympanometry comparisons. Results: The Transient Evoked Otoacoustic Emission failure rate for the group was 20.3%. The failure rate for pure tone screening was found to be 8.9%, whilst 18.6% of subjects failed a protocol consisting of combined pure tone screening and tympanometry results. In essence, findings from the comparison of overall Transient Evoked Otoacoustic Emission pass/fail with overall pure tone screening pass/fail suggested that use of a modified Rhode Island Hearing Assessment Project criterion would result in a very high probability that a child with a pass result has normal hearing (true negative). However, the hit rate was only moderate. Selection of a signal-to-noise ratio (SNR) criterion set at greater than or equal to 1 dB appeared to provide the best test performance measures for the range of SNR values investigated. Test performance measures generally declined when tympanometry results were included, with the exception of lower false alarm rates and higher positive predictive values. The exclusion of low frequency data from the Transient Evoked Otoacoustic Emission SNR versus pure tone screening analysis resulted in improved performance measures. Conclusions: The present study poses several implications for the clinical implementation of Transient Evoked Otoacoustic Emission screening for entry level school children. Transient Evoked Otoacoustic Emission pass/fail criteria will require revision. The findings of the current investigation offer support to the possible replacement of pure tone screening with Transient Evoked Otoacoustic Emission testing for 6-year-old children. However, they do not suggest the replacement of the pure tone screening plus tympanometry battery. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Aetiology of Papillon LeFevre Syndrome

Papillon LeFevre Syndrome, or PLS, was first described over 70 years ago. It is characterised by severe periodontal disease, typically leading to loss of teeth by adolescence, combined with palmoplantar hyperkeratosis. The fact that it is associated with consanguinity in particular ethnic groups suggests that genotype may contribute to the aetiology of this syndrome. Microbiological studies have been hampered by the rareness of the condition which makes prospective studies virtually impossible to perform. Numerous studies on small groups of patients, sometimes single cases, together suggest an association of recognised periodontal pathogens with PLS. Actinobacillus actinomycetemcomitans has been especially linked to PLS and raised levels of antibody to A.a. have been measured in some PLS patients, though not others. Porphyromonas gingivalis and Prevotella intermedia have also been detected in plaque samples from PLS, using monoclonal antibodies. Many other species have also been associated with PLS following culture and identification, as well as use of probes. Treatment has been attempted by eradication of periodontal pathogens so that teeth can erupt into a 'safe' environment. Successful treatment has needed intensive treatment and monitoring and good oral hygiene as well as thorough antibiotic therapy of patient, family members and even pets. Recently a Cathepsin C genotype has been strongly linked to PLS. However, this gene cannot account for all features of PLS and we can speculate that additional genes must be involved. It is concluded that PLS results from a combination of host and bacterial factors, including recessive human gene(s) associated with consanguinity, specific periodontal pathogens and lack of thorough oral hygiene. It is also believed that the human genetic component may merit examination as a 'host factor' in other bacterial infections. (C) 2001 Academic Press.

Investigations into a power-combining structure using a reflect array of dual-feed aperture-coupled microstrip patch antennas

This paper details an investigation of a power combiner that uses a reflect array of dual-feed aperture-coupled microstrip patch antennas and a corporate-fed dual-polarized array as a signal distributing/combining device. In this configuration, elements of the reflect array receive a linearly polarized wave and retransmit it with an orthogonal polarization using variable-length sections of microstrip lines connecting receive and transmit ports. By applying appropriate lengths of these delay lines, the array focuses the transmitted wave onto the feed array. The operation of the combiner is investigated for a small-size circular reflect array for the cases of -3 dB, -6 dB and -10 dB edge illumination by the 2 x 2-element dual-polarized array.

Use of cyclic variation of integrated backscatter to assess contractile reserve and myocardial viability in chronic ischemic left ventricular dysfunction

The detection of viable myocardium has important implications for management, but use of stress echocardiography to detect this is subjective and requires exposure to dobutamine. We investigated whether cyclic variation (CV) of integrated backscatter (IB) from the apical views could provide a resting study for detection of contractile reserve (CR) and prediction of myocardial viability in 27 patients with chronic ischemic left ventricular (LV) dysfunction. Repeat echocardiography was performed after 6.7 +/- 3.8 months of follow-up; 14 patients underwent revascularization and 13 were treated medically. Using a standardized dobutamine echocardiography (DbE) protocol, images from three apical views were acquired at 80-120 frames/sec at rest and during stress. CR was identified if improvement of wall motion was observed at low dose (5 or 10 mug/kg/min) DbE. Myocardial viability was characterized by improvement at follow-up echocardiography in patients with revascularization. CVIB at rest and low dose dobutamine were assessed in 194 segments with resting asynergy (severe hypokinesis or akinesis), of which 88 (45%) were in patients who underwent revascularization. Of these, CVIB could be measured in 190 (98%) segments at rest and 185 (95%) at low dose dobutamine. Sixty-two (33%) segments had CR during low dose DbE and 50 (57%) segments showed wall-motion recovery (myocardial viability) at follow-up echocardiography. Segments with CR had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P = 0.005) than segments without CR. Using optimal thresholds of CVIB (> 8.2 dB) at rest, the accuracy of CVIB for detecting CR was 70%. Compared with nonviable segments, viable segments had significantly higher CVIB at rest (P < 0.001) and low dose dobutamine (P < 0.001). Using optimal thresholds of CVIB (> 5.3 dB) at rest, the accuracy of CVIB for detecting myocardial viability was 85%, which was higher than that in conventional DbE (62%, P < 0.01). Thus, assessment of CV.TB from the apical views is a feasible and accurate tool for detecting CR and predicting myocardial viability in chronic LV dysfunction.

Resistively loaded helical antennas for ground-penetrating radar

Resistively loaded helical antennas, used in the normal mode and horizontally polarised, are modelled using the moment method above typical lossy ground. The distributed resistive loading was adjusted to maintain a two octave bandwidth. The centre frequency of 1 m dipoles was reduced from 250 MHz for the straight resistive wire to 50 MHz for a helix of pitch 2.5 cm and diameter 5 cm. The reduction in efficiency required to maintain the bandwidth for this helix was 12 dB. This agrees reasonably with the theory for small antennas in free space. The results were also verified by comparing measurements performed on a monopole resistively loaded helical antenna in a watertank with the numerical model used elsewhere.

Investigation of ultrasonic properties of PAG and MAGIC polymer gel dosimeters

Ultrasonic speed of propagation and attenuation were investigated as a function of absorbed radiation dose in PAG and MAGIC polymer gel dosimeters. Both PAG and MAGIC gel dosimeters displayed a dependence of ultrasonic parameters on absorbed dose with attenuation displaying significant changes in the dose range investigated. The ultrasonic attenuation dose sensitivity at 4 MHz in MAGIC gels was determined to be 4.7 +/- 0.3 dB m(-1) Gy(-1) and for PAG 3.9 +/- 0.3 dB m(-1) Gy(-1). Ultrasonic speed dose sensitivities were 0.178 +/- 0.006 m s(-1) Gy(-1) for MAGIC gel and -0.44 +/- 0.02 m s(-1) Gy(-1) for PAG. Density and compressional elastic modulus were investigated to explain the different sensitivities of ultrasonic speed to radiation for PAG and MAGIC gels. The different sensitivities were found to be due to differences in the compressional elastic modulus as a function of dose for the two formulations. To understand the physical phenomena underlying the increase in ultrasonic attenuation with dose, the viscoelastic properties of the gels were studied. Results suggest that at ultrasonic frequencies, attenuation in polymer gel dosimeters is primarily due to volume viscosity. It is concluded that ultrasonic attenuation significantly increases with absorbed dose. Also, the ultrasonic speed in polymer gel dosimeters is affected by changes in dosimeter elastic modulus that are likely to be a result of polymerization. It is suggested that ultrasound is a sufficiently sensitive technique for polymer gel dosimetry.

Otimização do layout de marcenarias no sul do espírito santo baseado em parâmetros ergonômicos e de produtividade

Este estudo foi realizado em três marcenarias no sul do Estado do Espírito Santo, com o objetivo de analisar o layout e propor mudanças que otimizem o funcionamento harmônico entre o local de trabalho e o trabalhador, considerando-se fatores ergonômicos, fluxo de produção e produtividade. A coleta de dados foi feita analisando-se as condições do ambiente de trabalho (clima, ruído, iluminação) e aplicando uma entrevista para avaliar as condições gerais e de segurança no trabalho. O layout foi avaliado por medições, observação da sequência de trabalho nas máquinas e aplicação do software AutoCAD 2000. Os resultados indicaram que o Índice de Bulbo Úmido e o Termômetro de Globo estavam de acordo com a Norma Regulamentadora nº 15 (atividade moderada), sendo de 26,38 ºC, em média. Os níveis médios de ruído foram de 87,48 dB (A), acima do permitido para uma jornada de 8 h diárias (NR 15). A luminosidade média, encontrada em duas marcenarias, ficou acima da faixa de iluminação mínima recomendada para esse trabalho de maquinarias (NBR 5413/92). Todas as marcenarias tinham disposição desordenada do maquinário em razão da sequência lógica de trabalho, presença de pilastras e resíduos na área útil e de passagem, piso desnivelado, falta de rampas para acesso aos galpões, manutenção de máquinas e equipamentos de forma incorreta, falhas no telhado e ausência de bancadas para facilitar a adoção de uma melhor postura durante o manuseio das peças.

Efeito do estímulo facilitador no limiar de reflexo acústico

A sensibilização auditiva, ferramenta utilizada na pesquisa dos reflexos acústicos, permite a redução do limiar de reflexo acústico a partir de um estímulo facilitador. Ele pode ser apresentado antes ou simultaneamente ao tom eliciador do reflexo acústico. São comparados os limiares pré e pós-exposição ao estímulo, esperando-se obter a redução do limiar. A partir do estudo dos reflexos acústicos é possível obter maiores informações a respeito das vias auditivas, como estruturas do tronco encefálico, visto que o arco reflexo está relacionado a núcleos auditivos nessa região. Eles também estão envolvidos no processamento auditivo. Assim, alterações do reflexo acústico poderiam estar relacionadas a falhas em habilidades de processamento auditivo. OBJETIVO: Esta pesquisa teve o objetivo de estudar a sensibilização do reflexo acústico a partir de um estímulo facilitador de 6 KHz. FORMA DE ESTUDO: Estudo clínico com coorte transversal. MATERIAL E MÉTODO: jovens mulheres com idade entre 20 e 25 anos, sem queixas audiológicas e limiares auditivos dentro dos limites da normalidade. RESULTADOS:Foi encontrada redução significativa do limiar de reflexo acústico entre 6,71 e 17,23 dB nas orelhas em que houve a sensibilização. CONCLUSÃO: A apresentação simultânea de um estímulo facilitador de alta freqüência gera redução do limiar de reflexo acústico em pessoas com audição dentro dos limites da normalidade.

Reconhecimento de fala no ruído em jovens e idosos com perda auditiva

Muitas pesquisas têm buscado investigar a interferência do ruído na percepção de fala de ouvintes. OBJETIVO: Este estudo foi realizado com a finalidade de pesquisar os efeitos da perda auditiva e da idade no reconhecimento de fala na presença de ruído, utilizando-se dois tipos de ruído. FORMA DE ESTUDO: Clínico prospectivo. MATERIAL E MÉTODO: Três grupos experimentais foram organizados, sendo um composto por adultos sem alteração auditiva, outro por sujeitos adultos com perda auditiva em freqüências altas e, por último, um grupo de idosos, com configuração audiométrica semelhante ao grupo de adultos com perda. Todos os sujeitos realizaram tarefas de reconhecimento de fala em silêncio, na presença de ruído branco de espectro ampliado e ruído "cocktail party", na mesma relação sinal/ruído (0 dB), em ambas as orelhas. RESULTADO: Os resultados mostraram que o ruído interfere negativamente no reconhecimento de fala em todos os grupos. O desempenho dos sujeitos com audição normal foi superior aos grupos com perda auditiva. Contudo, o grupo de idosos teve pior desempenho, sendo mais evidente com o ruído "coktail party". Observou-se também que todos os sujeitos apresentaram melhores resultados na segunda orelha testada, mostrando o efeito de aprendizagem. CONCLUSÃO: Estes achados apontam que a idade, além da perda auditiva contribui para o baixo desempenho de idosos na percepção de fala na presença de ruído e que o ruído "cocktail party" se mostrou adequado para esta investigação.

Estudo do efeito aprendizagem em exames audiométricos sequenciais de trabalhadores de indústria metalúrgica e suas implicações nos programas de conservação auditiva

A avaliação audiométrica é crucial nos programas de prevenção das disacusias ocupacionais. Exames periódicos são comparados, um a um, com um exame admissional e a ocorrência de pioras desencadeia ações preventivas sobre o trabalhador e seu posto de trabalho. Muitos trabalhadores "melhoram" seus limiares, nos primeiros anos, devido ao efeito aprendizagem. Se tais melhoras forem contempladas pela legislação, a detecção das perdas auditivas poderá ser antecipada. OBJETIVO: Identificar o efeito aprendizagem nas audiometrias industriais e avaliar suas implicações, particularmente sobre a validade do exame audiométrico admissional. FORMA DE ESTUDO: Clínico retrospectivo. MATERIAL E MÉTODO: Foram analisados 835 audiogramas de 167 metalúrgicos e comparados cinco exames periódicos com o respectivo exame admissional. Foram consideradas como efeito aprendizagem as melhoras de 5 dB em freqüências isoladas ou em grupos de freqüências. RESULTADOS: De 92 a 96% dos trabalhadores apresentaram melhoras de 5 dB, entre 500 e 6.000 Hz, no período pesquisado. De 31 a 37% apresentaram melhoras de 5 dB, do segundo para o primeiro exame e de 23 a 35%, do quinto para o primeiro. Na média aritmética dos limiares em 500, 1.000 e 2.000 Hz e em 3.000, 4.000 e 6.000 Hz, de 16 a 23% apresentaram melhoras do segundo para o primeiro exame e de 11 a 15%, do quinto para o primeiro. CONCLUSÕES: O efeito aprendizagem produziu melhoras dos limiares tonais em mais de um terço da população estudada, nos seis primeiros exames audiométricos seqüenciais. Questiona-se, assim, a validade do primeiro exame audiométrico como referencial, para ser comparado com os seqüenciais.