Evaluation of methods to reduce formaldehyde levels of cadavers in the dissection laboratory

Dissection of conventionally embalmed cadavers exposes students, staff, and faculty to formaldehyde, a probable carcinogen. Therefore, prudent practices should seek to minimize formaldehyde exposure. In this study, we evaluated two commercially available chemicals, InfuTrace and Perfect Solution, for their effectiveness in reducing ambient formaldehyde levels. Four cadavers embalmed conventionally with formaldehyde and/or with the above agents were compared for their formaldehyde levels under conditions that strictly controlled for air circulation and for locations and methods of testing, and during activities that simulated student dissecting. For InfuTrace, one cadaver was reinfused with InfuTrace after initial standard perfusion with formaldehyde; a second cadaver had InfuTrace injected into the thoracic and abdominal body cavities after formaldehyde perfusion. For Perfect Solution, the product was used for embalming a third cadaver in lieu of formaldehyde. For a control, a fourth cadaver was embalmed with the standard formaldehyde solution. Testing of personal and ambient room air samples and of fluid obtained from the cadavers was performed and analyzed in a blinded fashion. Results indicated that both Perfect Solution, substituted for standard formaldehyde embalming, and InfuTrace infused through the vasculature after formaldehyde embalming, resulted in lower concentrations of formaldehyde than embalming with formaldehyde solution alone or in combination with body cavity injection of InfuTrace. These differences in formaldehyde concentrations are consistent across measuring methods, for example, of room air, of breathing zone air during cadaver handling and dissection, and of liquid samples obtained from the cadavers. Perfect Solution yielded suboptimum fixation and a different texture, color, and smell than the formaldehyde treatments.     

Human preservation techniques in anatomy: A 21st century medical education perspective

Anatomy is the cornerstone of education for healthcare professionals with the use of human material providing an excellent teaching tool in the modern curricula. The ability and quality of preservation of human remains has enabled such use. The introduction of formaldehyde as a preservative in 1893 was an important step in the history of preservation. With the European Union directive on the use of formaldehyde and its expected banning, anatomists are trying to find a more convenient and safe substitute. In this review, we compare the different techniques used based on the need for embalming, fixative used, period of preservation and the features of the embalmed specimen. The fact that embalming is used in different disciplines, multiple purposes and described in different languages has led to the development of ambiguous interchangeable terminology. Overall, there is a lack of information specifically classifying, listing and comparing different embalming techniques, and this may be due to the fact that no internationally recognized experimental standards are adhered to in this field. Anatomists strive to find an embalming technique that allows the preserved specimen to accurately resemble the living tissue, preserve the body for a long period of time and reduces health risk concerns related to working with cadavers. There is a need for embalming to shift to an independent modern day science with well‐founded research at the heart of it. While this may take time and agreement across nations, we feel that this review adds to the literature to provide a variety of different methods that can be employed for human tissue preservation depending on the desired outcome. Clin. Anat. 28:725–734, 2015. © 2015 Wiley Periodicals, Inc.     

Preservation of neural tissue with a formaldehyde‐free phenol‐based embalming protocol

The adverse effects formaldehyde fixation has on tissues both gross anatomically and histologically are well documented. Consequently, researchers are seeking alternative embalming techniques that better preserve in vivo characteristics of tissues. Phenol‐based embalming is one method that has shown promise in its ability to adequately preserve the in vivo qualities of tissues through preliminary explorations at the gross anatomical level. The literature on phenol‐based embalming is currently scarce, especially with regard to its effects on tissues at the microscopic level. For the current study we aimed to document the histologic effects of a formaldehyde‐free phenol‐based embalming solution on neural tissue, with the hope of providing novel insight into the effects of soft‐embalming on tissues at the microscopic level. Cerebral and cerebellar tissue obtained from porcine brains was fixed in phenol‐ and formaldehyde‐based fixatives; the latter served as a control. Fixed samples were processed for histological analysis. The phenol‐based embalming solution provided excellent preservation of the cerebral and cerebellar tissue morphology. Of note was the decrease in separation artifact seen in both tissue types relative to the control tissue, as well as anomalous circular artifacts in the white matter. The results of this study indicate that the phenol‐based embalming solution preserves neural tissue at the histological level, perhaps superiorly in many aspects when compared to the formaldehyde‐fixed samples. Further investigations of both gross anatomy and histology are recommended on the basis of these promising new findings to determine its potential utilities within research and education. Clin. Anat. 32:224–230, 2019. © 2018 Wiley Periodicals, Inc.     

Flammability and combustion hazard of preserved human tissues

Preservation techniques have evolved over the years to respond to the need of longer dissection periods, with formaldehyde being widely used for this purpose. In recent years, efforts have been focusing on reducing the health hazards of this fixative and the rigidity of the tissues embalmed with it. With every embalming technique that they are either developing or resurrecting from various protocols, institutions need to assess the fire and health hazards of all the chemicals being used. Compliance with the storage and handling safeguards listed in the Material Safety Data Sheet of each chemical, needs to be accompanied by infrastructure changes. To reduce the health hazards of formaldehyde, institutions are taking appropriate countermeasures directed at the source itself, by using substitutes or injecting formaldehyde chelating agents, and are adopting high performance air extraction systems to protect the users. However, little is known about the flammability risk of embalmed human bodies. During a recent visit to McGill University morgue by architects and safety inspectors to expand it, we were asked about the flammability risk of the embalmed specimens, so we carried out a flashpoint test to evaluate the flammability potential of specimens embalmed with each of our three embalming techniques: formaldehyde-based, Thiel, and phenol-based. With the phenol-based embalming showing the most risks, attention should be drawn to all institutions who are experimenting with various embalming techniques to evaluate the flammability potential of their embalmed specimens.     

甲醛遗体防腐剂改良研究

目的　为减少甲醛防腐剂对人体造成的危害,研制新型改良甲醛遗体防腐剂EM1。 方法　通过甲醛释放量检测、细菌定量杀灭试验与真菌杀灭试验、实验室大鼠注射防腐实验、殡仪馆遗体防腐现场实验,考察遗体防腐剂的消毒、防腐效果。 结果　EM1防腐剂甲醛释放量为常规防腐剂的35.7%;能有效杀灭金黄色葡萄球菌和大肠杆菌等微生物;使用EM1进行注射防腐的大鼠可保存30d,且比Dodge处理的大鼠更接近活体状态;室温下对遗体的有效防腐率达95%以上。 结论　EM1防腐剂具有毒性低、防腐固定效果好、所保存的标本收缩率小、色泽接近活体状态等特点,可防止病原微生物的滋生传播,控制组织自溶、腐败的发展,利于医学解剖科研或殡仪馆遗体防腐保存。     

Reduction of formaldehyde concentrations in the air and cadaveric tissues by ammonium carbonate

The reduction of formaldehyde by ammonium carbonate was examined in cadavers and in vitro. Formaldehyde concentrations in the air (10 cm above human cadavers) and in various cadaveric tissues were measured with or without perfusion of ammonium carbonate solution into formaldehyde-fixed cadavers. Air samples were monitored using Kitagawa gas detector tubes. For measurement of formaldehyde in tissues, muscles and organs were cut into small pieces and tissue fluids were separated out by centrifugation. These specimen fluids were diluted, supplemented with 3-methyl-2-benzothiazolinone hydrazone hydrochloride and quantified by spectrophotometry. In five cadavers without ammonium carbonate treatment, the formaldehyde concentrations in the air above the thorax and in various tissue fluids were 1.2-3.0 p.p.m. and 0.15-0.53%, respectively. Arterial reperfusion of saturated ammonium carbonate solution (1.0, 1.5 or 2.0 L) into five formaldehyde-fixed cadavers successfully reduced the formaldehyde levels, both in the air (0.5-1.0 p.p.m.) and in various tissue fluids (0.012-0.36%). In vitro experiments demonstrated that formaldehyde concentrations decreased, first rapidly and then gradually, with the addition of ammonium carbonate solution into fluids containing formaldehyde. It was confirmed that formaldehyde reacted with the ammonium carbonate and was thereby changed into harmless hexamethylenetetramine. The application of ammonium carbonate solution via intravascular perfusion and, if necessary, by infusion into the thoracic and peritoneal cavities, injection into muscles and spraying on denuded tissues can be anticipated to reduce formaldehyde to satisfactorily low levels in cadaveric tissues and, consequently, in the air, which may provide safe and odorless dissecting rooms.     

Human body preservation – old and new techniques

This review deals with the art of (anatomical) embalming. The first part contains a brief historical review of the history of embalming, starting with ancient cultures such as the Egyptians and the lesser known Chinchorro culture, then going down the centuries and describing the anatomical techniques developed over the last two centuries. The second part deals in detail with the chemicals used for embalming purposes. The third part deals with several approaches to evaluating embalming methods, their suitability for biomechanical testing, antimicrobial properties, histological appearance, and usability. The fourth and final part analyze the European Biocidal Products Directive (98/8/EC) in the light of embalming.     

三七复方合剂对甲醛熏染大鼠睾丸组织雄激素受体和c-kit表达的影响

目的 通过检测三七复方合剂对甲醛熏染大鼠睾丸生精小管的形态学变化和睾丸组织雄激素受体(AR)和酪氨酸蛋白激酶受体c-kit的表达,验证三七复方合剂对慢性甲醛熏染的疗效。 方法 将18 只SD 雄性大鼠随机均分为对照组、甲醛组和治疗组,其中甲醛组和治疗组在甲醛熏染箱内熏染8周（8h/d）,治疗组自第5周起每天给予三七复方合剂灌胃治疗,持续4周。实验结束时,所有大鼠称量体重和睾丸重量,组织切片行HE染色和免疫组织化学检测,观察睾丸生精小管的形态学变化及睾丸组织AR和c-kit的表达。 结果 甲醛组鼠重和睾丸重量明显下降;经三七复方合剂治疗后,鼠重和睾丸重量较甲醛组明显增加（P<0.05）。甲醛组大鼠的睾丸生精小管萎缩,小管上皮层细胞排列紊乱,精子明显减少;三七复方治疗4周后基本恢复正常,管腔内可见大量精子。甲醛组睾丸组织ＡＲ和酪氨酸蛋白激酶受体c-kit表达明显减弱,治疗组生精上皮细胞的雄激素受体和酪氨酸蛋白激酶受体c-kit表达明显增强（P<0.05）,达到正常水平。 结论 较长时间甲醛熏染可使大鼠的体重和睾丸重量下降,生精小管损伤,睾丸组织中多种细胞AR和酪氨酸蛋白激酶受体c-kit的表达下降,三七复方合剂的应用有较明显治疗效果。     

Neutralisation of SARS-CoV-2 by anatomical embalming solutions

Teaching and learning anatomy by using human cadaveric specimens has been a foundation of medical and biomedical teaching for hundreds of years. Therefore, the majority of institutions that teach topographical anatomy rely on body donation programmes to provide specimens for both undergraduate and postgraduate teaching of gross anatomy. The COVID-19 pandemic has posed an unprecedented challenge to anatomy teaching because of the suspension of donor acceptance at most institutions. This was largely due to concerns about the potential transmissibility of the SARS-CoV-2 virus and the absence of data about the ability of embalming solutions to neutralise the virus. Twenty embalming solutions commonly used in institutions in the United Kingdom and Ireland were tested for their ability to neutralise SARS-CoV-2, using an established cytotoxicity assay. All embalming solutions tested neutralised SARS-CoV-2, with the majority of solutions being effective at high-working dilutions. These results suggest that successful embalming with the tested solutions can neutralise the SARS-CoV-2 virus, thereby facilitating the safe resumption of body donation programmes and cadaveric anatomy teaching.     

Elastic properties of Thiel‐embalmed human ankle tendon and ligament

Thiel embalming is recommended as an alternative to formalin‐based embalming because it preserves tissue elasticity, color, and flexibility in the long term, with low infection and toxicity risk. The degree to which Thiel embalming preserves elasticity has so far been assessed mainly by subjective scoring, with little quantitative verification. The aim of this study is to quantify the effect of Thiel embalming on the elastic properties of human ankle tendons and ligament. Biomechanical tensile tests were carried out on six Thiel‐embalmed samples each of the peroneus longus, peroneus brevis, and calcaneal tendons, and the calcaneofibular ligament, with strain rates of 0.25%s^?1, 2%s^?1, and 8%s^?1. The stress?strain relationship was calculated from the force‐extension response with cross‐sectional area and gauge length. Young's modulus was determined from the stress?strain curve. The results showed that the tendon and ligament elasticity were lower after Thiel embalming than the literature values for fresh nonembalmed tendons and ligament. The biomechanical tensile test showed that the measured elasticity of Thiel‐embalmed tendons and ligaments increased with the strain rate. The Thiel embalming method is useful for preserving human ankle tendons and ligaments for anatomy and surgery teaching and research, but users need to be aware of its softening effects. The method retains the mechanical strain rate effect on tendons and ligament. Clin. Anat. 28:917–924, 2015. © 2015 Wiley Periodicals, Inc.     

Cytotoxicity of formaldehyde on human osteoblastic cells is related to intracellular glutathione levels

Formaldehyde that leaches out of formaldehyde-releasing root canal sealers, specifically from setting material extruded into the periapical region may participate in the development of periapical inflammation or the continuation of a pre-existing periapical lesion. However, the effects of formaldehyde on human osteoblasts have not been investigated. The aim of this study was to evaluate the mechanisms of cytotoxicity of formaldehyde on human osteoblastic cell line U2OS in vitro. Cytotoxicity and cell proliferation assays were performed to elucidate the adverse effects of formaldehyde on U2OS cells. Formaldehyde demonstrated a cytotoxic effect to U2OS cells in a dose-dependent manner (p<0.05). The 50% inhibition concentration of formaldehyde was about 3 mM. Formaldehyde also inhibited cell proliferation during a 3-day culture period (p<0.05). To determine whether glutathione (GSH) levels were important in the cytotoxicity of formaldehyde, we pretreated cells with the GSH precursor, 2-oxothiazolidine-4-carboxylic acid (OTZ) to boost thiol levels, or buthionine sulfoximine (BSO) to deplete GSH. The addition of OTZ acted as a protective effect on the formaldehyde-induced cytotoxicity (p<0.05). In contrast, the addition of BSO enhanced the formaldehyde-induced cytotoxicity (p<0.05). Taken together, the levels of formaldehyde tested inhibited cell growth and proliferation on U2OS cells. Formaldehyde has significant potential for periapical toxicity. These inhibitory effects were associated with intracellular GSH levels.     

Involvement of cerebrovascular semicarbazide-sensitive amine oxidase in the pathogenesis of Alzheimer's disease and vascular dementia.

Fibrillary tangles and senile plaques resulting from advanced aggregation of beta-amyloid and other proteins are pathological characteristics of Alzheimer's disease (AD). Cerebral amyloid angiopathy is quite common in AD. In fact, amyloid fibrils fuse to and emanate from the vascular basement membrane. Semicarbazide-sensitive amine oxidase (SSAO), located in outer membranes of vascular smooth muscles and endothelia, catalyzes deamination of methylamine-producing formaldehyde and hydrogen peroxide. SSAO is also involved in lymphocyte adhesion and is up-regulated in response to inflammation. SSAO-mediated generation of formaldehyde can induce protein (i.e. beta-amyloid) cross-linkage, deposition and subsequently plaque formation in the compartment adjacent to the cerebrovessels. Formaldehyde may cause cytotoxicity, which induces inflammation and release of more SSAO, producing a cascade of toxic cycle. Increased SSAO-mediated reaction may be chronically involved in the pathogenesis of vascular dementia and AD.     

Increased risk of allergy in children due to formaldehyde exposure in homes

BACKGROUND: Formaldehyde levels were measured in 80 houses in the Latrobe Valley, Victoria, Australia. An association between exposure to formaldehyde and sensitization to common aeroallergens has been suggested from animal trials, but no epidemiologic studies have tested this hypothesis. METHODS: A total of 148 children 7-14 years of age were included in the study, 53 of whom were asthmatic. Formaldehyde measurements were performed on four occasions between March 1994 and February 1995 with passive samplers. A respiratory questionnaire was completed, and skin prick tests were performed. RESULTS: The median indoor formaldehyde level was 15.8 microg/ m3(12.6ppb), with a maximum of 139 microg/m3 (111 ppb). There was an association between formaldehyde exposure and atopy, and the adjusted odds ratio was 1.40 (0.98-2.00, 95% CI) with an increase in bedroom formaldehyde levels of 10 microg/m3. Furthermore, more severe allergic sensitization was demonstrated with increasing formaldehyde exposure. On the other hand, there was no significant increase in the adjusted risk of asthma or respiratory symptoms with formaldehyde exposure. However, among children suffering from respiratory symptoms, more frequent symptoms were noted in those exposed to higher formaldehyde levels. CONCLUSIONS: Low-level exposure to indoor formaldehyde may increase the risk of allergic sensitization to common aeroallergens in children.     

甲醛炎性痛诱导脊髓后角HO-1蛋白表达改变及其对脊髓神经元凋亡的影响

目的:观察甲醛炎性痛大鼠脊髓后角HO-1蛋白表达改变以及HO-1对炎性痛大鼠脊髓神经元凋亡的影响。方法:采用Western blotting方法检测左、右两侧脊髓后角HO-1蛋白的表达,采用流式细胞技术检测脊髓神经元凋亡率。结果:与对照组相比,足底注射甲醛后HO-1蛋白表达明显上调,其中以注射甲醛后24 h升高最为明显,72 h仍高于对照组水平。左、右两侧脊髓后角HO-1蛋白表达无明显差异。与对照组比较,甲醛组大鼠脊髓神经元凋亡率明显升高;鞘内预先注射HO-1抑制剂ZnppIX可使甲醛诱导的自发痛反应程度明显降低,并可使甲醛炎性痛大鼠脊髓神经元凋亡率进一步升高。结论:甲醛炎性痛可诱导大鼠脊髓后角HO-1蛋白表达升高,并可诱导脊髓神经元发生凋亡,甲醛炎性痛诱导的HO-1表达增强在脊髓伤害性信息传递过程中起促进作用;在炎性痛诱导的脊髓神经元凋亡过程中起抑制作用。     

甲醛熏染模型大鼠肝脏组织增殖细胞核抗原表达与三七复方合剂的干预

背景：甲醛作为一种有毒物质可给人体带来严重的损害,同时又缺少有效的防治方法。 目的：观察中药三七复方合剂对甲醛熏染大鼠肝细胞增殖的影响。 方法：将SD大鼠随机分成对照组、甲醛组和三七治疗组。对照组不做任何处理;甲醛组每天置于静态熏染箱内行甲醛熏染,连续8周;三七治疗组处理同甲醛组,但自第5周起,每日给予三七复方合剂灌胃1次。 结果与结论：苏木精-伊红染色结果显示,甲醛熏染8周甲醛组大鼠肝组织肝小叶形态结构紊乱、肝细胞呈现明显的增殖现象,窦间隙缩窄,而三七治疗组肝组织的形态结构明显恢复。免疫组织化学结果显示,甲醛组大鼠肝组织增殖细胞核抗原阳性细胞数明显多于对照组(P < 0.01),而三七治疗组与甲醛组相比则明显降低(P < 0.01)。结果证实,三七复方合剂能够降低由甲醛诱发的肝组织增殖细胞核抗原的表达,可有效减缓由甲醛诱发的大鼠肝细胞增殖。     

Optimal Design of Needle Array for Effective Drug Delivery

Recently, the multi-needle drug injection has been adopted to overcome the shortcomes of conventional single-needle injection, enhancing the efficiency of drug delivery. However, the effect of needle array on the efficacy of drug delivery has not been fully elucidated. In this study, the interactions of drug analogous solution injected from a pair of needles were analyzed to examine the design criteria of effective multi-needle devices for drug delivery. Temporal and spatial variations of relative contents of the solution in the tissues were compared according to the distance between two adjacent needles (DN). As the DN increases from 5 to 20 D, where D is the needle diameter, the solution from each needle encounters 3.5 times faster, and 4.22 times more solution was accumulated. At the same time, the effective spreading area was continuously increased from 54.2 to 177.8 mm² and RCS gradient decreases from 0.087 to 0.037, due to the overlapping effect of the spreading solution from neighboring needles. Finally, based on the experimental results, an optimal design criterion of needle array for effective drug delivery was proposed. The present results would be helpful in the design of multi-needle injection devices and eventually offer advantage to patients with effective drug delivery.     

Impact of drying and thiel embalming on mechanical properties of achilles tendons

Biomechanical research and orthopedic training is regularly carried out on human cadavers. Given the post‐mortem decay, these cadavers were usually frozen or embalmed. The embalming method according to Dr. Thiel was often praised for the preservation of natural texture. The main aim of this article was to quantitatively analyze the impact of this embalming technique on the biomechanical properties. To that extent, Achilles tendons (calcaneal tendons) of seven cadavers have been tested. For each cadaver, a first tendon was tested following a fresh‐frozen conservation, the other following the Thiel embalming process. The results indicated a significant difference in Young's modulus between both groups (P values = 0.046). The secondary aim of this article was to analyze the impact of exposure to room conditions and associated dehydration on the biomechanical properties of cadaver tissue. Therefore, each tendon was tested before and after 2 hr of exposure to room conditions. The resulting dehydration caused a significant increase of the Young's modulus for the thawed fresh‐frozen tendons. The properties of the Thiel embalmed tendons were not significantly altered. In conclusion, this research promoted the use of fresh‐frozen specimens for biomechanical testing. Effort should, however, be made to minimize dehydration of the tested specimens. Clin. Anat. 28:994–1001, 2015. © 2015 Wiley Periodicals, Inc.     

Enhanced magnitude and breadth of neutralizing humoral response to a DNA vaccine targeting the DHBV envelope protein delivered by in vivo electroporation

We explored in the duck hepatitis B virus (DHBV) model the impact of electroporation (EP)-mediated DNA vaccine delivery on the neutralizing humoral response to viral preS/S large envelope protein. EP enhanced the kinetics and magnitude of anti-preS response compared to the standard needle DNA injection (SI). Importantly, EP dramatically enhanced the neutralizing potency of the humoral response, since antibodies induced by low DNA dose (10 μg) were able to highly neutralize DHBV and to recognize ten antigenic regions, including four neutralization epitopes. Whereas, SI-induced antibodies by the same low DNA dose were not neutralizing and the epitope pattern was extremely narrow, since it was limited to only one epitope. Thus, EP-based delivery was able to improve the dose efficiency of DNA vaccine and to maintain a highly neutralizing, multi-specific B-cell response, suggesting that it may be an effective approach for chronic hepatitis B therapy at clinically feasible DNA dose.