畸变产物耳声发射对侧抑制效应的临床应用价值

目的：为观察畸变产物耳声发射（ＤＰＯＡＥ）对侧抑制效应的临床应用价值。方法：研究以白噪声为对侧声刺激,对１７例正常人（３４耳）,１３例蜗性聋（１３耳）,９例蜗后聋（９耳）进行了ＤＰＯＡＥ及其对偶抑制效应测试。结果：蜗性聋耳的ＤＰＯＡＥ幅值较正常耳显著下降（Ｐ〈０．０１）,对偶抑制效应减弱,但与正常人差异无统计学意义（Ｐ〉０．０５）,蜗后聋耳ＤＰＯＡＥ幅值高于正常耳（Ｐ〉０．０５）,对侧抑制效应显著     

The global potential for increased storage of carbon on land

Constraining the climate crisis requires urgent action to reduce anthropogenic emissions while simultaneously removing carbon dioxide from the atmosphere. Improved information about the maximum magnitude and spatial distribution of opportunities for additional land-based removals of CO₂ is needed to guide on-the-ground decision-making about where to implement climate change mitigation strategies. Here, we present a globally consistent spatial dataset (approximately 500-m resolution) of current, potential, and unrealized potential carbon storage in woody plant biomass and soil organic matter. We also provide a framework for prioritizing actions related to the restoration, management, and maintenance of woody carbon stocks and associated soils. By comparing current to potential carbon storage, while excluding areas critical to food production and human habitation, we find 287 petagrams (PgC) of unrealized potential storage opportunity, of which 78% (224 PgC) is in biomass and 22% (63 PgC) is in soil. Improved management of existing forests may offer nearly three-fourths (206 PgC) of the total unrealized potential, with the majority (71%) concentrated in tropical ecosystems. However, climate change is a source of considerable uncertainty. While additional research is needed to understand the impact of natural disturbances and biophysical feedbacks, we project that the potential for additional carbon storage in woody biomass will increase (+17%) by 2050 despite projected decreases (−12%) in the tropics. Our results establish an absolute reference point and conceptual framework for national and jurisdictional prioritization of locations and actions to increase land-based carbon storage.

Emissions of carbon to the atmosphere must remain below ∼250 petagrams (PgC) (918 PgCO₂) from 2021 onward to achieve the Paris Agreement’s goal of limiting global temperature rise to well below 2 °C (1–3). At present rates, that amount of carbon will be emitted by 2045. It follows that even necessary and drastic cuts in emissions (i.e., a rapid transition from fossil fuels to renewable energy sources) must be accompanied by carbon dioxide removal (CDR) or negative emissions strategies (4). Promising options for large-scale CDR include improved land stewardship (5), commonly referred to as natural climate solutions (NCS) (6–8). In particular, increasing carbon storage in woody biomass (e.g., forest ecosystems) is widely recognized as having high climate mitigation potential while also affording an array of environmental and socio-economic cobenefits (6–9). While a growing body of research has estimated the near-term potential for land-based climate mitigation (6, 8, 10), these studies emphasize the climate benefit over short, 10- to 30-y planning horizons. They do not include estimates of the upper limit for additional land-based carbon storage or its spatial distribution. This information is essential for landscape-level planning and targeted implementation of NCS, given that the potential for additional carbon storage is necessarily defined by both the rate at which carbon can be sequestered and the magnitude of the available reservoir. Therefore, we provide 500-m-resolution global maps to quantify the maximum potential for additional carbon storage in ecosystems dominated by woody vegetation (i.e., trees and shrubs), under baseline (1960 to 1990) and future (representative concentration pathway scenario 8.5 [RCP8.5]) climate conditions. This information can be used to help direct NCS toward areas with the greatest maximum opportunity, inform when NCS will saturate, and identify the types of NCS actions that are best suited to a given location.One approach to estimating maximum additional carbon storage—or the difference between current and potential carbon, which we term “unrealized potential” carbon—is a bookkeeping approach that tracks carbon fluxes through time. Under this approach, net land-based emissions since 1850 are estimated to have been 108 to 188 PgC, including both biomass (above and below ground) and soil organic matter (13–17). Estimates that account for preindustrial (i.e., pre-1850) land use are more varied and increase post-1850 estimates by as much as 325 to 357 PgC (18) or as little as 48 to 153 PgC (11–13, 15). This high uncertainty limits the practical utility of this approach.Other investigators have sought instead to quantify unrealized potential by comparing estimates of current and potential land carbon storage. Sanderman et al. (6), considering only soil organic carbon (SOC), estimated net losses in the upper 2 m of soil from agricultural land use to be 116 PgC since 10,000 BC. Erb et al. (19), focusing on changes in vegetation biomass, found losses in carbon due to human land use to be significantly larger (447 PgC) than the studies cited above that consider only the postindustrial period, but generally consistent with some of those that account for preindustrial human disturbance (18). Bastin et al. (20), in a study focused on the restoration of global tree cover, identified an additional reservoir of 206 PgC when considering all carbon pools (aboveground and belowground biomass, soil, litter, and dead wood) after excluding cropland and urban areas.However, all of these global analyses fall short in delivering the robust spatially explicit information needed for targeted planning and implementation of landscape-level NCS. While the global dataset produced by Bastin et al. (20) has a reasonably high spatial resolution (30 arc seconds; approximately 900 m) and considers all land carbon pools, the product is limited to the storage potential afforded by the expansion of tree cover. Moreover, the result is subject to the uncertainty inherent in indirect estimates of carbon stock from area-based metrics of tree/forest cover (21). In comparison, the data product created by Erb et al. (19), which is based on several disparate yet direct estimates of terrestrial carbon storage, is limited by its treatment of only the biomass carbon pool and coarse spatial resolution (5 arc min; approximately 9.3 km). The authors themselves remark that “the uncertainty range could be narrowed if a single robust, validated method would be applied continuously in the stocktaking efforts” (19).Here, we apply a consistent suite of methods to generate spatially explicit global estimates of current (ca. 2016) and climate-constrained potential land carbon storage in aboveground woody biomass (AGB), belowground woody biomass (BGB), and SOC pools at a spatial resolution of approximately 500 m. The difference between current and potential land carbon storage represents the unrealized potential for additional carbon accumulation in global woody biomass and soils. We then disaggregate this global estimate of unrealized potential carbon storage using a conceptual framework we term the NCS opportunity space: seven discrete, internally consistent, and spatially explicit categories of broad NCS action (Fig. 1). Categories are defined quantitatively in terms of woody carbon density, thereby avoiding the uncertainty associated with derivative approximations of potential carbon storage based on forest area or canopy cover. After applying safeguards to lands currently utilized for food production, human habitation (e.g., urban areas), and sensitive biodiversity (nonwoody grasslands), we demonstrate the utility of the opportunity space framework for landscape-level NCS planning by analyzing the global, regional, and national potential for additional land carbon storage attributable to restoration (e.g., reforestation), management (e.g., improved natural forest stewardship), and maintenance (i.e., the sequestration benefit accrued through avoided forest conversion) of woody carbon stocks and associated soils. Finally, we evaluate the uncertainty that climate change poses to the magnitude and spatial distribution of the unrealized potential for additional carbon storage through 2050.Open in a separate windowFig. 1.The NCS opportunity space, consisting of seven categories defined by the ratio of current (x axis) to potential (y axis) carbon storage as well as carbon-based thresholds delineating NCS-relevant systems. Categories include: Restore/High suitability for forestry-based NCS (R/H; red), Maintain and manage/High suitability for forestry-based NCS (MM/H; dark green), Maintain/High suitability for forestry-based NCS (M/H; dark blue), Restore/Low suitability for forestry-based NCS (R/L; orange), Maintain and manage/Low suitability for forestry-based NCS (MM/L; light green), Maintain/Low suitability for forestry-based NCS (M/L; light blue), and Nonwoody (yellow). † denotes associated grassland/savanna biodiversity considerations.     

Otoacoustic emissions: assessment of hearing after tympanostomy tube insertion

This study evaluates the use of transient evoked otoacoustic emissions as an alternative to pure tone audiometry for the assesment of hearing after tympanostomy tube insertion. Otoacoustic emissions and pure tone audiometry were carried out in 32 patients in whom tympanostomy tubes had been inserted. Otoacoustic emissions were detected in 78% of patients, whereas pure tone audiometry testing was only possible in 59%. Of 13 children who were 3 years of age or under, otoacoustic emissions could be measured in 62%, compared to pure tone audiometry which was only possible in 8%. Otoacoustic emission testing took on average 3 min, which was less than half the time for pure tone audiometry testing which took 7 min.     

The feasibility of recording transiently evoked otoacoustic emissions immediately following grommet insertion

The demonstration of normal hearing following grommet insertion in young or difficult to test children can be problematic. This study aims to determine whether transiently evoked otoacoustic emissions (TEOAEs), can be recorded in the operating theatre, immediately after grommet insertion, and whether this technique has any advantages over conventional testing to exclude sensorineural loss. One ear of each of 80 children was studied, using the Otodynamics ILO88 OAE analyser. Responses were normal in eight, reduced in 31 and absent in 39. Bleeding prevented the performance of the test in two children. We conclude that TEOAEs can be recorded in 50% of ears immediately after grommet insertion, but the responses are reduced compared with normal ears. This application of TEOAEs may be a useful supplement to behavioural tests, but we do not advocate it as a screening technique.     

耳声发射在低频感音神经性聋诊断中的应用

报告利用耳动态分析仪ＩＬＯ－９２，对５４例低频感音神经性聋患者进行了畸变产物耳声发射，瞬态诱发性耳声发射和自发性耳声发射测试。发现突聋和梅尼埃病人的ＴＥＯＡＥ检出率为４８％，ＤＰＯＡＥ的检出率为９１％，且有２例记录到ＳＯＡＥ波。而在不是原因听力下降组中，ＯＡＥ的检出率为１００％，且可记录到ＳＯＡＥ。     

ABR和DPOAE在高胆红素血症新生儿听力筛查中的应用

目的探讨听性脑干反应(ABR)及畸变产物耳声发射(DPOAE)对高胆红素血症新生儿听力筛查的临床意义,为早期干预治疗提供依据.方法对170例高胆红素血症新生儿进行ABR和DPOAE检查,对其中部分异常者6个月后复查.结果 170例患儿中,ABR和DPOAE的总异常率分别为54.12%和32.65%;血清胆红素水平越高,ABR和DPOAE异常率越高(P<0.01),ABR异常越严重(P<0.01);胆红素浓度恢复正常后6个月复查ABR和DPOAE,恢复率分别为77.12%和77.01%,其中ABR异常DPOAE正常耳较两者均异常耳容易恢复(P<0.01).结论 ABR和DPOAE联合应用对高胆红素血症新生儿听力的早期定量定位评估比单独应用更准确和全面.     

Increased risk of chronic obstructive pulmonary diseases in coke oven workers: interaction between occupational exposure and smoking

BACKGROUND: Coke oven workers are regularly exposed to coke oven emissions (COE) and may be at risk of developing lung diseases. There is limited evidence for the link between exposure to COE and chronic obstructive pulmonary diseases (COPD). The aim of this study was to explore the dose-response relationship between COE exposure and COPD and to assess the interaction with cigarette smoking. METHODS: Seven hundred and twelve coke oven workers and 211 controls were investigated in southern China. Benzene soluble fraction (BSF) concentrations as a surrogate of COE were measured in representative personal samples and the individual cumulative COE exposure level was quantitatively estimated. Detailed information on smoking habits and respiratory symptoms was collected and spirometric tests were performed. RESULTS: The mean BSF levels at the top of two coking plants were 743.8 and 190.5 microg/m3, respectively, which exceed the OSHA standard (150 microg/m3). After adjusting for cigarette smoking and other risk factors, there was a significant dose-dependent reduction in lung function and increased risks of chronic cough/phlegm and COPD in coke oven workers. The odds ratio for COPD was 5.80 (95% confidence interval 3.13 to 10.76) for high level cumulative COE exposure (> or =1714.0 microg/m3-years) compared with controls. The interaction between COE exposure and smoking in COPD was significant. The risk of COPD in those with the highest cumulative exposure to COE and cigarette smoking was 58-fold compared with non-smokers not exposed to COE. CONCLUSION: Long term exposure to COE increases the risk of an interaction between COPD and cigarette smoking.     

新生儿短纯音诱发耳声发射的刺激水平探析

目的:探析短纯音诱发耳声发射(tone-burst-evoked otoacoustic emissions,TBOAEs)测试新生儿内耳功能时所应选用的适当刺激水平。方法:选取2012年1月至2013年1月河南省人民医院耳鼻喉科检查的80例正常新生儿为研究对象,分别以60、65、70、75、80 dB peSPL五种刺激强度进行测试,分析最佳刺激水平。结果:各项参数在低刺激水平(60、65 dB peSPL)和高刺激水平(70、75、80 dB peSPL)上有明显区别,差异有统计学意义(P<0.05)。结论:75、80 dB peSPL刺激水平是测试评估新生儿内耳功能的合适选择。     

基层医院新生儿听力筛查及相关影响因素

目的：通过对新生儿听力筛查,探讨基层医院新生儿听力筛查的适宜时间、初筛通过率、新生儿听力异常发病率,并分析听力筛查相关影响因素。方法采用瞬态诱发耳声发射技术（TEOAE）对2010年1月至2012年12月在本院住院的5746例新生儿进行听力筛查,初筛未通过者于生后42d进行复筛,复筛仍未通过者,于生后3个月进行第3次筛查,未通过者采用脑干听觉诱发电位技术诊断,并对听力筛查者的相关影响因素统计分析。结果正常新生儿生后4-7d初筛通过率最高,初筛通过率为93.5%（5025/5374）,高危儿初筛通过率为76.6％（285/372）,两组差异显著。经听性脑干反应测试诊断为听力障碍6例,新生儿听力异常发病率为3.4‰。结论新生儿听力筛查可及早发现听力障碍,正常新生儿初筛时间以生后4-7d最佳,高危新生儿听力障碍的发生率高于正常新生儿,应重点监测。     

Salient features of otoacoustic emissions are common across tetrapod groups and suggest shared properties of generation mechanisms

Otoacoustic emissions (OAEs) are faint sounds generated by healthy inner ears that provide a window into the study of auditory mechanics. All vertebrate classes exhibit OAEs to varying degrees, yet the biophysical origins are still not well understood. Here, we analyzed both spontaneous (SOAE) and stimulus-frequency (SFOAE) otoacoustic emissions from a bird (barn owl, Tyto alba) and a lizard (green anole, Anolis carolinensis). These species possess highly disparate macromorphologies of the inner ear relative to each other and to mammals, thereby allowing for novel insights into the biomechanical mechanisms underlying OAE generation. All ears exhibited robust OAE activity, and our chief observation was that SFOAE phase accumulation between adjacent SOAE peak frequencies clustered about an integral number of cycles. Being highly similar to published results from human ears, we argue that these data indicate a common underlying generator mechanism of OAEs across all vertebrates, despite the absence of morphological features thought essential to mammalian cochlear mechanics. We suggest that otoacoustic emissions originate from phase coherence in a system of coupled oscillators, which is consistent with the notion of “coherent reflection” but does not explicitly require a mammalian-type traveling wave. Furthermore, comparison between SFOAE delays and auditory nerve fiber responses for the barn owl strengthens the notion that most OAE delay can be attributed to tuning.Numerous fundamental biophysical questions regarding cochlear mechanics remain unanswered, such as the relative dominance between viscous and inertial fluid forces affecting the stimulation of hair cells and the longitudinal coupling between them (1, 2). These aspects, combined with relative experimental inaccessibility, have led to much uncertainty with regard to the micromechanics at work in the organ of Corti, and thereby precisely how auditory information is initially peripherally encoded (i.e., forward transduction). One area in which there is broad agreement, however, is the notion of an “active” ear: A nonlinear amplification mechanism(s) (i.e., reverse transduction) boosts detection of low-level sounds and compresses a wide range of sound intensities into a narrower range of vibration magnitude (3). One manifestation of this process is the existence of otoacoustic emissions (OAEs), sounds measurable noninvasively in the external ear canal using a sensitive microphone (4). Because only healthy ears tend to emit, OAEs have had a significant clinical impact (e.g., pediatric audiology). Emissions can arise spontaneously (SOAEs) or be evoked by an external stimulus. In fact, SOAEs are commonly pointed to as salient evidence for active amplification, especially given their connections to perception such as “rippling” in audiograms (threshold microstructure), indicative of localized changes in detection thresholds (5, 6). SOAEs are, however, idiosyncratic in nature: Not all mammalian species have them, whereas several nonmammalian classes such as lizards exhibit robust activity. Humans have a high incidence of SOAEs, although some (healthy) ears have them but others do not. So, although SOAEs are not required per se for sensitive hearing, they provide a powerful and noninvasive means to study the function of the inner ear.A common thread through vertebrate OAEs studies is that of an active oscillator, typically a stereovillar hair cell, acting as the essential transducer (3, 7–10). A comprehensive theory for SOAE generation across vertebrates is lacking, however, because knowledge of hair cell physiology has not yet been well connected to the collective behavior of the system as a whole. Vertebrate ears contain anywhere from 50 to 20,000 hair cells, all coupled together to varying degrees. Two different, and seemingly diametric, theoretical approaches explaining SOAEs have emerged. One model class considers the ear as a system of coupled nonlinear oscillators exhibiting a limit cycle (3, 11–13). Typically, these models are “local” in that a given oscillator is only directly coupled to its nearest neighbors. The other class focuses predominantly on the mammalian cochlea (14–19), where “global” coupling between elements arises from the hydromechanics that give rise to wave mechanics. One salient example is the standing wave model (16), where the peak of the traveling wave and stapes act as the two reflecting boundaries with a nonuniform gain medium in between, somewhat akin to a laser. That study predicted and verified interrelationships between spontaneous and evoked OAEs. Furthermore, acknowledging that nonmammalian ears exhibit different mechanics, Shera (16) proposed that the appearance of “standing waves” need not necessarily depend upon traveling waves along the basilar membrane (BM) but could arise via other mechanisms that create appropriate phase differences (e.g., delays due to tuning). Motivated by the uncertain role of BM traveling waves in nonmammals, our present goal was to exploit the large morphological differences that exist across vertebrate ears (20) to gain quantitative insight into SOAE generation mechanisms.Here we focus on two different nonmammalian species: a bird, the barn owl, and a lizard, the green anole. Both species exhibit robust OAE activity (21–25). The barn owl (Tyto alba), is known for its remarkable ability to hunt by auditory cues alone (26). The peripheral auditory morphology, neurophysiology, and psychophysics of this species have been well characterized (27–30). Owl auditory nerve fiber (ANF) responses show average frequency tuning but have remarkably high phase-locking capabilities extending out to 10 kHz (31). Furthermore, the tonotopic map along the basilar papilla (in contrast to the mammalian organ of Corti) is nonexponential, with representation of higher frequencies (5–10 kHz) greatly expanded. The role of BM waves is unknown in owls, although data from pigeons are suggestive of their existence in birds (32). The inner ear of lizards is profoundly different from that of both humans and barn owls. In anoles, the short auditory papilla (∼0.5 mm) contains ∼150 hair cells and has no overlying tectorial membrane over the SOAE-producing cells (33). Bundle orientations for hair cells in a given radial cross-section are arranged in a self-opposing fashion. Furthermore, there is ample evidence indicating a lack of a traveling wave on the BM (34, 35). In this study, we systematically explored interrelationships within individual ears between SOAEs and stimulus frequency emissions (SFOAEs), the simplest type of evoked emission via a single low-level stimulus tone (15). In short, we found that important OAE characteristics are shared between the two species and with published data from humans. This we interpret as revealing generic features of the underlying active processes.