诊断超声的生物效应与安全性研究进展

超声作为一种便捷的无电离辐射的影像学方法广泛用于临床,但其生物学效应与安全性需要得到足够的重视.超声的生物学效应包括热效应与机械效应,实验证明其对生物不同组织均有不同程度的影响.随着超声造影与超声弹性成像的发展,超声新技术的生物效应研究不断深入开展.通过阐述近年对诊断超声的生物学效应与安全性研究,能够更深入了解超声生物...     

Ultrasound: biological effects and industrial hygiene concerns

Due to the increased use of high intensity ultrasonic devices, there is now a greater risk of worker exposure to ultrasonic radiation than there was in the past. Exposure to high power ultrasound may produce adverse biological effects. High power ultrasound, characterized by high intensity outputs at frequencies of 20-100 kHz, has a wide range of applications throughout industry. Future applications may involve equipment with higher energy outputs. Contact ultrasound, i.e., no airspace between the energy source and the biological tissue, is significantly more hazardous than exposure to airborne ultrasound because air transmits less than one percent of the energy. This paper discusses biological effects associated with overexposure to ultrasound, exposure standards proposed for airborne and contact ultrasound, industrial hygiene controls that can be employed to minimize exposure, and the instrumentation that is required for evaluating exposures.     

The safety of prenatal ultrasound exposure in human studies

Diagnostic ultrasound use in obstetrics has been growing rapidly to become an integral part of prenatal care today. The high proportion of exposure to prenatal ultrasound highlights the public health significance of routine ultrasound use. A majority of epidemiologic studies tends to support the safety of diagnostic ultrasound use during pregnancy. However, there have been some reports that there may be a relation between prenatal ultrasound exposure and adverse outcome. Some of the reported effects include growth restriction, delayed speech, dyslexia, and non-right-handedness associated with ultrasound exposure. Continued research is needed to evaluate the potential adverse effects of ultrasound exposure during pregnancy. These studies should measure the acoustic output, exposure time, number of exposures per subject, and the timing during the pregnancy when exposure(s) occurred, while controlling for potential confounding variables such as sociodemographic, medical, and obstetric risk factors. We recommend that a new consensus development conference be held to gather the needed data and provide guidelines for the future research needs, as well as respond to the rapid advances in this technology.     

超声能源在去肾交感治疗中的应用

以Symplicity^TM为代表的利用射频能量行去肾交感神经术开创了经皮血管介入治疗顽固性高血压的全新途径。但射频能量消融尚存在消融效率较低、消融时患者疼痛明显、部分患者对治疗无反应（约20%）及完成治疗过程依耐于标准的患者血管类型等缺点。而超声作为一种频率高于听阈的机械波,在生物组织中以纵波传播时,其携带的机械能可使介质中的分子剧烈震荡产生机械摩擦、空化和热效应等,因此可用于去肾交感神经术。且与射频能量消融相比,超声能量在安全性和有效性方面有诸多优势。本综述即将对经导管超声消融肾交感神经相关研究进展作一系统阐述。     

Perspectives on reproductive and developmental toxicity

Human reproduction and development is a cycle of interdependent events. Virtually all of its phases have been shown to be the primary target of one or more non-mutagenic exogenous agents. Such agents interfere with certain of the countless epigenetic or ontogenic events essential for normal completion of the cycle. Mutagens disrupt this cycle at some points, but the overwhelming majority of reproductive and developmental toxins are not mutagenic. As in all aspects of toxicology, the reproductive and developmental effects of chemicals are determined by the intrinsic nature of the chemical, the quantity of the chemical exposure, the duration of exposure and the stage of the cycle at which it occurs. Signs of reproductive toxicity range from reduced fertility to spontaneous abortion. Adverse effects on the conceptus are categorized as functional deficits, developmental retardation, structural abnormality and death. One or more of these is anticipated to occur as a result of excess exposure to most chemicals. Although the degree of hazard and risk potential can be calculated in each instance, chemicals differ markedly in their ability to interfere with reproduction (Amann, 1982) and/or development (Johnson, 1984). Standardized methods for reproductive and developmental toxicity safety evaluation are available for detecting adverse effects upon any aspect of reproduction and development. Data currently available establish that these state-of-the-art tests conducted in laboratory animals are often highly predictive of the type of adverse effect a particular chemical will have in humans, as well as the exposure level at which it will occur. By adding a modest safety factor to the no-observed-effect-level of well-executed animal studies, safe human exposure levels can be established. Responsibility for determining the intrinsic hazard potential and the risk estimate of exposure rests with manufacturers and major users of occupational and other environmental chemicals. As public awareness of reproductive and developmental hazards has increased in recent years, it has come to be understood that some chemicals have a predilection for causing reproductive impairment and/or disrupting development in the absence of other toxicity. Such substances must be identified to establish safe exposure levels and to determine the types of effects to be expected, should excessive human exposure occur. The setting of safe exposure levels is necessary both from the standpoints of ensuring public safety and avoiding product liability.     

New EMF safety limits for occupational and public exposure in Poland

On July 23, 2001, new safety limits for occupational exposure to electromagnetic fields (EMF) were introduced in Poland. The limits have been based on the analysis of international recommendations, e.g., ICNIRP (1998), WHO (1998), IEEE standard (1999), drafts of European standards (ENV 1995), and a critical review of the world literature on the biological effects of EMF and health effects of exposure to EMF. Derived from safety limits for occupational exposure, new safety exposure limits for general population were introduced on November 28, 2003. In this paper mandatory procedures for setting limits of exposure to agents harmful to health in the workplace and natural environment are presented. The most essential provisions of two regulations, one issued by the Minister of Labour and Social Policy and the other by the Minister of the Environment, forming the basis of the modern system of EMF exposure control in Poland, are also discussed.     

On estimating average effects for multiple treatment groups

We propose to estimate average exposure (or treatment) effects from observational data for multiple exposure groups by fitting an approximation of the marginal sample distribution of the response variable in each exposure group to the data. The marginal sample distribution is a function of the true distribution of the response variable in the population and the assignment rule governing the allocation of the subjects to different exposure groups. The assignment rule can depend on the response variable in addition to measured covariates, and hence the method is appropriate even when the assumption of ignorable treatment assignment is not justified. We estimate the exposure effects are estimated based on the population expectation (PE) of the outcome variable. We compare the PE approach with an instrumental variable method and with several other methods including propensity score based approaches that assume ignorable assignment mechanisms. We evaluate the robustness of the PE method under model misspecifications and illustrate it using data from a study of the impact of soy consumption on urinary concentrations of estrogen and estrogen metabolites in Asian American women. Published 2012. This article is a US Government work and is in the public domain in the USA.     

Significance of ultrasonic studies in urologic diagnosis

This report on urological diagnostic is based on more than thousand ultrasonography scans. A set shows the most evident pathological situations in relation to the most evident complaints. The immense possibilities of ultrasound scan in urology are demonstrated through examples and the sense of the scan is discussed. Because there is no harm it is recommended that the ultrasound diagnostic should be used at the beginning of the diagnostic procedures.     

A flexible parametric approach for estimating continuous‐time inverse probability of treatment and censoring weights

Marginal structural Cox models are used for quantifying marginal treatment effects on outcome event hazard function. Such models are estimated using inverse probability of treatment and censoring (IPTC) weighting, which properly accounts for the impact of time‐dependent confounders, avoiding conditioning on factors on the causal pathway. To estimate the IPTC weights, the treatment assignment mechanism is conventionally modeled in discrete time. While this is natural in situations where treatment information is recorded at scheduled follow‐up visits, in other contexts, the events specifying the treatment history can be modeled in continuous time using the tools of event history analysis. This is particularly the case for treatment procedures, such as surgeries. In this paper, we propose a novel approach for flexible parametric estimation of continuous‐time IPTC weights and illustrate it in assessing the relationship between metastasectomy and mortality in metastatic renal cell carcinoma patients. Copyright © 2016 John Wiley & Sons, Ltd.     

上海市“九五”期间X射线诊断医疗照射剂量水平调查

[目的 ]　了解上海市“九五”期间X射线诊断医疗照射所致公众的剂量水平。　 [方法 ]　用TLD剂量计调查上海市 19种X射线诊断平均每次检查受检者体表剂量 ,估算平均每次检查所致受检者各器官吸收剂量及全身有效剂量当量 ,再结合上海市医疗照射调查频率数据 ,进一步估算X射线诊断检查所致公众集体剂量负担。　 [结果 ]　上海市19种X射线诊断检查所致公众年集体剂量当量 1996年为 5 2 0 .92人·Sv ,1998年为 5 46.93人·Sv ;19种X射线诊断检查所致全市年人均有效剂量当量 1996年为 0 .0 40mSv ,1998年为 0 .0 42mSv。　 [结论 ]　上海市X射线诊断医疗照射的剂量水平有增高的趋势 ,应重视医疗照射正确合理应用的问题     

高频彩色多普勒超声对浅表软组织肿物的诊断价值

目的：探讨高频彩色多普勒超声对浅表软组织肿物的诊断价值。方法：纳入2015年5月～2020年5月本院收治的经手术和病理证实的浅表软组织肿物患者86例为观察对象,行高频彩色多普勒超声检查,将其检查结果与手术病理结果进行对照分析。结果：86例浅表肿物中,高频彩色多普勒超声诊断为良性的78例,恶性8例,与病理结果对照分析,诊断符合率为93.02%。对肿物类型的判断,超声有13例误诊。彩色多普勒显示,恶性肿物均可见较丰富的血流信号,与良性肿物比较（除血管瘤、炎症外）,差异性显著（P<0.05）。结论：高频彩色多普勒超声对浅表软组织肿物良恶性的判断有较高的诊断价值,在对浅表软组织解剖结构熟悉的基础上,依据肿物发生的部位和声像图特征,并结合其临床表现,能对肿物的病理类型做出较准确的诊断。     

Tissue-specific toxicological effects of cadmium in green mussels (Perna viridis): nuclear magnetic resonance-based metabolomics study

Toxicity tests for metals have traditionally focused on selected biomarkers to characterize the biological stress induced by metals in marine organisms. Here nuclear magnetic resonance (NMR)-based metabolomics, a system biology tool, was applied to the marine green mussel, Perna viridis, to investigate the toxicological effects of Cd in both digestive gland and adductor muscle tissues. After Cd exposure for either two or four weeks, there was no significant metabolic change in the mussels exposed to Cd at 2?μg/L. At 20?μg/L, there were major metabolite changes related to amino acids, osmolytes, and energy metabolites. Digestive gland tissue was more sensitive to Cd than adductor muscle tissue. The adductor muscle tissue showed elevated levels of glutamine, glutamate, and lactate, and reduced levels of branched chain amino acids, aspartate, phenylalanine, and tyrosine. Overall, four weeks of Cd exposure produced neurotoxicity and metabolic disturbances and disturbed osmoregulation. These results suggest that the adductor muscle tissue of mussels may be a suitable supplemental biomarker for exposure to toxicants. In addition, the results demonstrate that (1) H-NMR-based metabolomic analysis can provide a systematic view of the toxicological effects of metals on mussels, suggesting that it might be employed to investigate the toxicological effects of other marine pollutants.     

Inorganic: the other mercury

There is a broad array of mercury species to which humans may be exposed. While exposure to methylmercury through fish consumption is widely recognized, the public is less aware of the sources and potential toxicity of inorganic forms of mercury. Some oral and laboratory thermometers, barometers, small batteries, thermostats, gas pressure regulators, light switches, dental amalgam fillings, cosmetic products, medications, cultural/religious practices, and gold mining all represent potential sources of exposure to inorganic forms of mercury. The route of exposure, the extent of absorption, the pharmacokinetics, and the effects all vary with the specific form of mercury and the magnitude and duration of exposure. If exposure is suspected, a number of tissue analyses can be conducted to confirm exposure or to determine whether an exposure might reasonably be expected to be biologically significant. By contrast with determination of exposure to methylmercury, for which hair and blood are credible indicators, urine is the preferred biological medium for the determination of exposure to inorganic mercury, including elemental mercury, with blood normally being of value only if exposure is ongoing. Although treatments are available to help rid the body of mercury in cases of extreme exposure, prevention of exposure will make such treatments unnecessary. Knowing the sources of mercury and avoiding unnecessary exposure are the prudent ways of preventing mercury intoxication. When exposure occurs, it should be kept in mind that not all unwanted exposures will result in adverse health consequences. In all cases, elimination of the source of exposure should be the first priority of public health officials.     

Determinants of wood dust exposure in the Danish furniture industry

This paper investigates the relation between wood dust exposure in the furniture industry and occupational hygiene variables. During the winter 1997-98 54 factories were visited and 2362 personal, passive inhalable dust samples were obtained; the geometric mean was 0.95 mg/m(3) and the geometric standard deviation was 2.08. In a first measuring round 1685 dust concentrations were obtained. For some of the workers repeated measurements were carried out 1 (351) and 2 weeks (326) after the first measurement. Hygiene variables like job, exhaust ventilation, cleaning procedures, etc., were documented. A multivariate analysis based on mixed effects models was used with hygiene variables being fixed effects and worker, machine, department and factory being random effects. A modified stepwise strategy of model making was adopted taking into account the hierarchically structured variables and making possible the exclusion of non-influential random as well as fixed effects. For woodworking, the following determinants of exposure increase the dust concentration: manual and automatic sanding and use of compressed air with fully automatic and semi-automatic machines and for cleaning of work pieces. Decreased dust exposure resulted from the use of compressed air with manual machines, working at fully automatic or semi-automatic machines, functioning exhaust ventilation, work on the night shift, daily cleaning of rooms, cleaning of work pieces with a brush, vacuum cleaning of machines, supplementary fresh air intake and safety representative elected within the last 2 yr. For handling and assembling, increased exposure results from work at automatic machines and presence of wood dust on the workpieces. Work on the evening shift, supplementary fresh air intake, work in a chair factory and special cleaning staff produced decreased exposure to wood dust. The implications of the results for the prevention of wood dust exposure are discussed.     

Occupational standards for the protection of employees in biotechnology

A growing number of employees are exposed to biological agents (BAs) at the workplace. Their handling can be associated with the risk of occupational illnesses like infections, allergic or toxic reactions. Several legal considerations are making requirements for the safe handling of BAs necessary. A specific risk assessment has to consider both the adverse health effects deriving from BAs and the exposure situation at the workplace. Industrial hygiene is of critical importance for safe handling, especially with regard to allergic reactions. Occupational surveillance programs can help to further minimize the risks, especially in preventing infections through vaccinations and in counseling persons with impaired immune systems. For accidental exposures medical emergency plans should be prepared. Occupational medical examination programs, vaccinations and counseling of employees must be adapted to the outcome of the risk assessment.     

Communicating the harmful effects of radiation exposure from medical imaging: malpractice considerations

Concerns about possible harmful effects of exposure to radiation arising from diagnostic radiologic procedures have existed in both the scientific and lay communities for many decades. There is, however, no question that the degree of concern over the past years has escalated to the "anxiety" if not the "fear" level. Potential exposure to radiation is not a new issue, but it is certainly a "hot" issue. Americans were exposed to more than six times as much ionizing radiation from diagnostic medical procedures in 2006 than they were in early 1980s. To what extent this increased exposure elevates the risk of genetic mutations and/or development of cancer is not known with any degree of certainty. The available data are subject to varying interpretations, often debatable and thus controversial. What should be communicated to the public? The medical and scientific communities must encourage public attention and discussion regarding radiologic imaging and associated radiation exposure. They must talk to the public sensibly about the uncertainty regarding the hazards of radiation exposure. Exposure to imaging involving radiation and the hazards related to such exposure has myriad medical/legal ramifications. There has never been a successful medical malpractice lawsuit that alleged development of cancer or genetic defects resulting from diagnostic x-ray examinations. However, there have been and continue to be lawsuits filed alleging soft tissue injury resulting from overexposure to diagnostic radiologic equipment and cancer caused by overexposure to radiation oncology equipment. It is quite likely that lawsuits alleging development of cancer arising from diagnostic imaging using standard levels of ionizing radiation will be forthcoming. How the courts will deal with these remains to be determined.     

生物组织弹性的测量与成像:基于振动的超声检测方法综述

生物组织力学特性的超声无损检测在生物医学的科学研究和临床实践中具有广泛的应用前景,是医学超声学研究的前沿课题。近二十年来,一些研究深入探讨了生物组织中振动的传播机制,提出了各种别具特色的组织弹性的超声测量和成像方法。这些方法有的采用外部振动单元产生激励,有的则利用声辐射力(Acoustic Radiation Force)将振动施加到生物组织内部,结合超声检测和信号处理技术,考察生物组织对振动激励的响应,实现组织弹性的测量与成像。本文主要对各种基于振动激励源的超声测量和成像方法进行综述。首先介绍相关的物理基础,然后简述典型方法的实现原理,最后探讨现阶段超声弹性测量和成像研究的不足,并对其未来的研究方向进行展望。     

Retention of Asbestos Bodies in the Lungs of Welders

Examination of asbestos bodies (AB) retained in the lungs is a useful way of assessing past occupational exposure to this material. AB retention has been extensively studied in workers directly exposed to asbestos, but less so in those end users, such as welders, who use asbestos-containing products. We therefore retrospectively studied AB retention in 211 welders, for whom biological testing procedures had been requested by a chest physician, between 1988 and 1991. Optical microscopy of AB was performed on samples of sputum (40 subjects), bronchoalveolar lavage fluid (BAL) (147 subjects), and lung tissue obtained after thoracotomy (38 subjects). Information on previous jobs and exposure was obtained using a questionnaire (the mean duration of welding activities was 16.6 years). Eighty-two subjects (38.9%) had elevated lung retention of AB in all the samples studied. Significant AB retention occurred in only 30% of sputum samples, but in 40.1% of BAL samples and 39.5% of lung tissue samples. The duration of welding activities correlated with the density of AB in BAL or lung tissue (r = 0.31, p < 0.01 and r = 0.49, p < 0.05, respectively). On the basis of the questionnaire, only two of the welders with significant AB retention had other occupational exposure to asbestos. Our findings suggest that welding activities may increase lung retention of AB, and consequently might produce higher risks of fibrotic and/or malignant pulmonary diseases. These potential risks need to be brought to the attention of doctors; a longitudinal follow-up may also be warranted in such populations, even after individuals have ceased their welding jobs.     

Extrapolating from toxicity data to occupational exposure limits: some considerations.

This paper evaluates procedures relevant to extrapolating from toxicity data in man and animals to Occupational Exposure Limits. It examines effects at or around the "No Observed Adverse Effect Level' (NOAEL) and the magnitude of safety factors which can be applied in developing occupational exposure limits for non-stochastic effects. The relationship between incidence of stochastic effect and occupational exposure limit is also discussed.     

Toxic megacolon in ulcerative colitis. Early diagnosis and management

The diagnosis of toxic megacolon is based on a thorough history and physical examination, simple laboratory tests, and careful examination of plain abdominal films. As with other uncommon conditions, making the correct diagnosis requires a high index of suspicion. This is especially true when toxic megacolon is the initial manifestation of ulcerative colitis. In this setting, a previous history of chronic diarrhea may be lacking. Patients with toxic megacolon are usually first seen in the emergency room, so the diagnosis must be entertained in all patients presenting with abdominal distention and acute or chronic diarrhea. The diagnosis of toxic megacolon does not require CT scans, ultrasound examinations, radionuclide scans, colonoscopy, or barium enema. In fact, reliance on those nonessential diagnostic procedures may delay diagnosis while the patient continues to deteriorate. Once toxic megacolon is diagnosed, the patient should be admitted immediately to an intensive care unit for careful monitoring by both medical and surgical staff.