Laboratory animal allergy: a British perspective on a global problem

In the United Kingdom, laboratory animal allergy (LAA) has been recognized as an important occupational disease for nearly 25 years. However, introduction of health and safety legislation (e.g., the Control of Substances Hazardous to Health Regulations of 1988) and an increasing knowledge of the factors that contribute to the etiology of this disease have had surprisingly little impact on the prevalence and incidence of LAA over the last 10 to 20 yr. Studies of the relation between exposure to animal allergens and the development of LAA reveal that the risk of disease increases with increasing intensity of exposure. Current evidence suggests that animal allergens are very potent, and substantial decreases in allergen exposure are therefore necessary before a reduction in symptoms will be observed. In the United Kingdom, it is unlikely that an Occupational Exposure Limit will be set for animal allergens in the near future, partly because an adequately standardized assay for quantifying exposure is not yet available. Prevention of LAA in the future will probably be driven by the needs of the industry and will most likely rely on the adoption of guidelines describing " best practise" which incorporate sophisticated engineering methods of controlling exposure to animal allergens.     

Laboratory animal allergy: an update

Allergic reactions are among the most common conditions affecting the health of workers involved in the care and use of research animals. Between 11 and 44% of the individuals working with laboratory animals report work-related allergic symptoms. Of those who become symptomatic, 4 to 22% may eventually develop occupational asthma that can persist even after exposure ceases. Allergic symptoms consist of rashes where animals are in contact with the skin, nasal congestion and sneezing, itchy eyes, and asthma (cough, wheezing, and chest tightness). The generation of immunoglobulin E (IgE) antibodies is a prerequisite for the production of allergic symptoms. The mechanism by which IgE antibodies develop is becoming clearer. The propensity to produce IgE is genetically determined, and pre-existing allergy may be a risk factor for the development of laboratory animal allergy (LAA). However, exposure to animal allergens is the major risk factor for the development of LAA. Techniques to measure the airborne concentration of laboratory animal allergens have been developed. Research on animal allergens themselves indicates that many of the mouse and rat urinary proteins belong to a family of proteins called lipocalins, which share sequence homology with antigens of the parasitic agent that causes schistosomiasis. The fact that parasite infections also trigger IgE antibody responses may account for the development of LAA in persons who have never had any previous allergy. The prevention of LAA should be a major goal of an effective health and safety program in the animal research facility, and it can be accomplished by education and training of employees, reduction of exposure (including the use of personal protective gear), and changes in facility design. Medical surveillance programs can also play a role in improving health of individuals working with laboratory research animals. Early recognition of symptoms and evidence of sensitization can lead to interventions to reduce exposure and thereby avoid the long-term health consequences of LAA.     

Laboratory animal allergies: overview of causation and prevention

In sensitized individuals, exposure to laboratory animal allergens can cause symptoms ranging in severity from annoying to life-threatening. The author presents an overview of the pathology of LAA and discusses a number of methods that can be used to limit exposure to these allergens.     

Assessment and treatment of laboratory animal allergy

Laboratory animal allergy (LAA) is a form of occupational sensitivity affecting up to one third or more of exposed workers. Symptoms involve the eyes, nose, skin, and lower respiratory tract. Asthma may develop in 20 to 30% of sensitized individuals. An occupational medical history is the primary tool if a diagnosis of LAA is suspected. The diagnosis is confirmed by demonstrating the presence of immunoglobulin E antibodies to laboratory animal allergens by skin testing or in vitro assays. If laboratory animal allergen-induced asthma is suspected, measurements of lung function are necessary for confirmation and assessing the degree of impairment. One approach to the problem is presented in this article. For individuals with LAA, avoidance of exposure is the primary treatment. For individuals who continue to work in the environment, pharmacological treatment of their symptoms may be necessary. Methods to prevent the development of LAA are also discussed.     

Mechanism and epidemiology of laboratory animal allergy

Laboratory animal allergy (LAA) is a form of occupational allergic disease. The development of laboratory animal allergy is due to the presence of IgE antibodies directed against animal proteins. The process of sensitization (development of IgE antibodies) is a complex process which involves interaction of antigen presenting cells and lymphocytes of the Th-2 cell type. These cells generate a host of cytokines and other factors which lead to immediate hypersensitivity reactions and other factors which lead to immediate hypersensitivity reactions and the generation of allergic inflammation. Typical symptoms of laboratory animal allergy include nasal symptoms, such as sneezing, watery discharge, and congestion. Skin rashes are also common. Asthma, which produces symptoms of cough, wheezing, and shortness of breath, may affect 20-38% of workers who are sensitized to laboratory animal allergens. Rarely a generalized, life-threatening allergic reaction (anaphylaxis) may occur. The estimated prevalence of laboratory animal allergy is variable depending on the method used for diagnosis, but nonetheless may affect up to 46% of exposed workers. The presence of pre-existing allergies to non-work place allergens (e.g., dust mite, pollens, molds), exposure to laboratory animal allergens, and possibly tobacco smoking are risk factors for the development of laboratory animal allergy. Progress in the understanding of the mechanism and epidemiology of laboratory animal allergy will lead to improved methods for its prevention.     

Comparison of Risk Factor between Lacunar Stroke and Large Artery Atherosclerosis Stroke: A Cross-Sectional Study in China

Background

Stroke is the second most common cause of mortality in China. Although most subtypes of ischemic stroke share similar risk factors, they have different etiologies. Our study aimed to evaluate the different risk factor profiles between the stroke subtypes, lacunar infarcts (LI) and large-artery atherosclerosis (LAA), and clarify the characteristics of current acute ischemic stroke in China.

Methods

In this cross-sectional study, we analyzed the clinical characteristics of 1982 patients with acute ischemic stroke who were admitted to the neurology department at the Peking University First Hospital between 2007 and 2014. Ischemic stroke was further classified into LAA, LI, cardioembolism (CE) and undetermined causes of infarction (UDI) according to TOAST classification. Demographic characteristics, risk factors, as well as the findings of laboratory and imaging tests of 1773 patients with LAA and LI, were analyzed by univariate and multivariate logistic analysis.

Results

Of the 1982 ischemic stroke patients included in this study, 1207 were diagnosed with LAA, 566 with LI, 173 with cardioembolism (CE) and 36 with undetermined causes of infarction (UDI). By comparing the risk factors in multivariate logistic regression analysis, hypertension [odds ratio (OR) = 1.832] and white matter leukoaraiosis (WML) (OR = 1.865) were found to be more strongly correlated with LI than LAA. Low density lipoprotein- cholesterol (LDL-c) (OR = 0.774) were more strongly related to LAA than LI.

Conclusions

This study found that hypertension and WML were more strongly correlated with LI than LAA. LDL-c was more strongly related to LAA than LI.     

Left Atrial Appendage Volume Increased in More Than Half of Patients with Cryptogenic Stroke

Background

Ischemic strokes without a well-defined etiology are labeled as cryptogenic, and account for 30–40% of strokes in stroke registries. The left atrial appendage (LAA) is the most typical origin for intracardiac thrombus formation when associated with atrial fibrillation. Here, we examined whether increased LAA volume detected with cardiac computed tomography (cCT) constitutes a risk factor in cryptogenic stroke patients.

Methods

This study included 82 stroke/TIA patients (57 males; mean age, 58 years) with a diagnosis of cryptogenic stroke after extensive radiological and cardiological investigations. Cases were classified using the TOAST criteria modified by European Association of Echocardiography recommendations for defining cardiac sources of embolism. Forty age- and gender-matched control subjects without cardiovascular diseases were selected for pair-wise comparisons (21 males; mean age, 54 years). LAA volume adjusted for body surface area was measured three dimensionally by tracing the LAA borders on electrocardiogram-gated CT slices.

Results

In control subjects, mean LAA volume was 3.4±1.1 mL/m². Mean+2SD, which was considered the upper limit for normal LAA volume was 5.6 mL/m². In paired Student t-test between the patient group and matched controls, LAA volume was 67% larger in cryptogenic stroke/TIA patients (5.7±2.0 mL/m² vs. 3.4±1.1 mL/m²; P<0.001). Forty-five (55%) patients with cryptogenic stroke/TIA had enlarged LAA.

Conclusion

LAA is significantly enlarged in more than half of patients with cryptogenic stroke/TIA. LAA thrombosis may contribute to the pathogenesis of stroke in patients considered to have cryptogenic stroke after conventional evaluation.     

Design,construction, and validation of a large capacity rodent magnetic field exposure laboratory

A magnetic field exposure laboratory has been constructed to support National Toxicology Program studies for the evaluation of the toxicity and carcinogenicity of pure, linearly polarized, 60 Hz magnetic fields in rodents. This dual corridor, controlled access facility can support the simultaneous exposure of 1200 rats and 1200 mice. The facility contains fully redundant electrical and environmental control systems and was constructed using non‐metallic materials to maintain low levels of background (ambient), stray, and cross‐talk magnetic fields. The exposure module design provides for large uniform exposure volumes with good control of stray and cross‐talk fields, while allowing the use of roll‐around cage racks for simplified animal husbandry. Stray fields and cross‐talk have been further reduced by the inclusion of “steering coils” in each exposure module. Ambient 60 Hz fields (less cross‐talk) in all exposure rooms are <0.1 μT (1 mG), and static magnetic fields have been mapped extensively. Magnetic field strength, waveform, temperature, relative humidity, light intensity, noise level, vibration, and air flow in all animal holding areas are tightly regulated, and are monitored continuously during all studies. Field uniformity in the animal exposure volumes is better than ±10%; a systematic program of cage, rack, and room rotation controls for possible positional effects within the exposure system. Magnetic fields are turned on and off over multiple cycles to prevent the induction of transients associated with abrupt field level changes. Total harmonic distortion is <3% at all field strengths. The facility has been used to study magnetic field bioeffects in rodent model systems in experiments ranging in duration from 8 weeks to 2 years. Bioelectromagnetics 20:13–23, 1999. © 1999 Wiley‐Liss, Inc.     

New Ventilated Isolation Cage

A multifunction lid has been developed for a commercially available transparent animal cage which permits feeding, watering, viewing, long-term holding, and local transport of laboratory rodents on experiment while isolating the surrounding environment. The cage is airtight except for its inlet and exhaust high-efficiency particulate air filters, and it is completely steam-sterilizable. Opening of the cage's feed and water ports causes an inrush of high velocity air which prevents back-migration of aerosols and permits feeding and watering while eliminating need for chemical vapor decontamination. Ventilation system design permits the holding in adjacent cages of animals infected with different organisms without danger of cross-contamination; leaves the animal room odor-free; reduces required bedding changes to twice a month or less, and provides investigators with capability to control precisely individual cage ventilation rates. Forty-eight cages can be conveniently placed on a standard NIH "shoebox" cage rack (60 inches wide x 28 inches deep x 74 inches high) fitted with a simple manifold exhaust system. The entire system is mobile, requiring only an electrical power outlet. Principal application of the caging system is in the area of preventing exposure of animal caretakers to pathogenic substances associated with the animal host, and in reducing handling of animals and their exposure to extraneous contamination.     

Animal models that elucidate basic principles of the developmental origins of adult diseases

Human epidemiological and animal laboratory studies show that suboptimal environments in the womb and during early neonatal life alter development and predispose the individual to lifelong health problems. The concept of the developmental origins of adult diseases has become well accepted because of the compelling animal studies that have precisely defined the outcomes of specific exposures such as nutrient restriction, overfeeding during pregnancy, maternal stress, and exogenously administered glucocorticoids. This review focuses on the use of animal models to evaluate exposures, mechanisms, and outcomes involved in developmental programming of hypertension, diabetes, obesity, and altered pituitary-adrenal function in offspring in later life. Ten principles of developmental programming are described as fundamental, regardless of the exposure during development and the physiological system involved in the altered outcome. The 10 principles are discussed in the context of the physiological systems involved and the animal model studies that have been conducted to evaluate exposures, mechanisms, and outcomes. For example, the fetus responds to challenges such as hypoxia and nutrient restriction in ways that help to ensure its survival, but this "developmental plasticity" may have long-term consequences that may not be beneficial in adult life. To understand developmental programming, which represents the interaction of nature and nurture, it is necessary to integrate whole animal systems physiology, in vitro cellular biology, and genomic and proteomic approaches, and to use animal models that are carefully characterized and appropriate for the questions under study. Animal models play an important role in this evaluation because they permit combined in vivo and in vitro study at different critical time windows during the exposure and the ensuing developmental responses.     

Low impedance walking robots

For both historical and technological reasons, most robots,including those meant to mimic animals or operate in naturalenvironments,³ use actuators and control systems that have high(stiff) mechanical impedance. By contrast, most animals exhibitlow (soft) impedance. While a robot's stiff joints may be programmedto closely imitate the recorded motion of an animal's soft joints,any unexpected position disturbances will generate reactiveforces and torques much higher for the robot than for the animal.The dual of this is also true: while an animal will react toa force disturbance by significantly yielding position, a typicalrobot will greatly resist. These differences cause three deleterious effects for high impedancerobots. First, the higher forces may cause damage to the robotor to its environment (which is particularly important if thatenvironment includes people). Second, the robot must acquirevery precise information about its position relative to theenvironment so as to minimize its velocity upon impact. Third,many of the self-stabilizing effects of natural dynamics are"shorted out"⁴ by the robot's high impedance, so that stabilizationrequires more effort from the control system. Over the past 5 yr, our laboratory has designed a series ofwalking robots based on "Series-Elastic Actuators" and "VirtualModel Control." Using these two techniques, we have been ableto build low-impedance walking robots that are both safe androbust, that operate blindly without any model of upcoming terrain,and that add minimal control effort in parallel to their self-stabilizingpassive dynamics. We have discovered that it is possible toachieve surprisingly effective ambulation from rather simplemechanisms and control systems. After describing the historicaland technological motivations for our approach, this paper givesan overview of our methods and shows some of the results wehave obtained.     

实验动物致敏研究进展

实验动物致敏（laboratory Animal Allergy,LAA）,是一种职业过敏性疾病,造成人的呼吸道及皮肤发生炎症。该病在国外研究较多,过敏源是动物皮毛、尿液、唾液中的一类酸性小分子蛋白质;可以通过皮肤试验、放射过敏吸附试验及ELISA等方法检测易感人员。对易感人员可以通过控制环境中的过敏原来保护。目前国内尚无专门机构研究此病症,笔者综述了该职业性疾病的症状、机理、控制方法及国内外对该病症认识上的差异。     

A proteomic approach to the identification of early molecular targets changed by L-ascorbic acid in NB4 human leukemia cells

The pro-oxidant effect of L-ascorbic acid (LAA) is toxic to leukemia cells. LAA induces the oxidation of glutathione to its oxidized form (GSSG) and this is followed by a concentration-dependent H(2)O(2) accumulation, which occurs in parallel to the induction of apoptosis. To identify early protein targets of LAA in leukemia cells, we used a differential proteomics approach in NB4 human leukemia cells treated with 0.5 mM of LAA for 30 min. This exposure was determined to efficiently block cellular proliferation and to activate oxidative stress-inducible apoptosis. We identified nine proteins that sensitively reacted to LAA treatment by using two-dimensional (2-D) gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight-MS. A subunit of protein-disulfide isomerase (a thiol/disulfide exchange catalyst) and immunoglobulin-heavy-chain binding protein (BiP, identical to Hsp70 chaperone) showed quantitative expression profile differences. A myeloid leukemia associated antigen protein (a tropomyosin isoform) showed changes in pI as a result of phosphorylation. Our studies demonstrate for the first time that the addition of LAA to cells results in an immediate change in the intracellular thiol/disulfide condition and that this includes an increase in the GSH oxidation with changes in the superfamily of thiol/disulfide exchange catalysts. These results suggest that LAA oxidizes intracellular reduced glutathione and modulates disulfide bond formation in proteins.     

Barriers to assessment and treatment of pain in laboratory animals

Pain is an undesirable potential consequence of many of the procedures conducted on animals in the course of scientific research, and in most cases it is unnecessary. The US Congress, the public, and laboratory animal medical professionals have indicated that pain should be prevented or minimized in laboratory animals, yet there is ample evidence to suggest that unalleviated pain is still a problem for some laboratory animals. This evidence is circumstantial to some extent but has its basis in problematic issues of pain control in both veterinary and human medicine. The author attempts to identify specific barriers to reduction of pain in laboratory animals. She then seeks to determine the relative importance of each obstacle and to develop approaches to overcoming each obstacle.     

Environmental enrichment for laboratory rodents

Modernization of housing and husbandry techniques for rodents has minimized confounding variables. The result has been vastly improved health maintenance and reproducibility of research findings, advances that have decreased the numbers of animals needed to attain statistically significant results. Even though not all aspects of rodent manipulation have been strictly defined, as housing and handling procedures have become increasingly standardized, many animal care personnel have recognized the lack of complexity of the rodents' environment. Concern for this aspect of animal well-being has led many research facilities to provide "environmental enrichment" for rodents. Additionally, regulatory agencies in the United States and Europe have also been increasingly concerned about this issue relative to laboratory animal husbandry. However, little is known about the influence such husbandry modifications may have on biological parameters. In this article, laws and guidelines relating to rodent enrichment are reviewed, the natural behaviors of select rodent species are discussed, and an overview of widely used types of enrichment in laboratory rodent management is provided. The literature evaluating effects of rodent enrichment is reviewed both in terms of neurological development and as an experimental variable, and results of a study evaluating the effect of enrichment on immune and physiological parameters are reported. Survey data on current enrichment practices in a large multi-institutional organization are presented, and practical aspects requiring consideration when devising a rodent enrichment program are discussed.     

The experiments with laboratory animals from a bioethical point of view--history, modern time, perspectives

The origin of laboratory animal science was called forth by violent development of experimental biology and medicine in the XIX century on the one hand, and on the other hand by the necessity to have standard healthy animals for experiments with strictly definite biological characteristics. With this aim in view management technology and animal use in experiments have been constantly improved. "Laboratory animal" notion has been formed by the end of the XIX century. At the beginning of laboratory animal science development ethical problems were not as urgent as they are now. It is established that the three Rs bioethical conception of W.M.S. Russel and R.L. Burch (1959) has influence on modern state and perspectives of the development of animal experimental methods. It is shown that the existence of laboratory animal protection laws and the reflection in them of compulsory ethical review of scientific project and statistics of used laboratory animals is absolutely necessary.     

The efficacy and safety of chlorpyrifos (Dursban) for control of Myobia musculi infestation in mice.

Mite infestation in laboratory mice is a common, but troublesome problem in animal facilities. Recommended treatment regimens are frequently ineffective because of the short period of exposure to the control agent. In an effort to develop a time-release approach, we have investigated the use of Dursban granules applied in animal bedding. Initial toxicity studies indicated that this pesticide can be added to shoebox cage litter at levels three times that used for outdoor application (6 g per 27 by 48 cm shoebox cage) without producing clinical signs of toxicity. Metabolism studies demonstrated that although individual mice showed decreased brain acetylcholinesterase activity following treatment, liver cytosolic glutathione-S-transferase, liver microsomal aminopyrine N-demethylase, or aryl hydrocarbon hydroxylase were not induced after 1 week of exposure. Parasitological studies indicated elimination of mites and itching in an experimental infestation, as well as reduction of itching in severely symptomatic, naturally infested mice, following treatment with the granules. These studies demonstrate the nontoxic efficacy of Dursban in the control of Myobia musculi.     

The muskrat in biomedical research

Muskrats are aquatic rodents of moderate size which are plentiful throughout North America, but are not used commonly in the laboratory. Recently, we tested the feasibility of muskrats as experimental models and have found them to be acquired and cared for easily in conventional laboratory animal facilities. Some of their natural characteristics and diseases are described. The husbandry techniques that we used are presented and form a base for the preparation of future guidelines for the maintenance and use of feral animals in research. The results of some initial experiments testing the muskrat's utility for investigations of cardiorespiratory control mechanisms also are presented. Our data show that even anesthetized muskrats possess brisk and dramatic cardiovascular and respiratory reflexes. Our findings that their brains possess the cytoarchitectural and myeloarchitectural features comparable to other mammals, combined with their relative uniformity in size, has allowed us to locate specific neuronal loci stereotaxically. We suggest that the muskrat be considered as an experimental animal model for studies of the neural control of cardiorespiratory systems.     

Amino acid abundance and composition in cell culture medium affects trace metal tolerance and cholesterol synthesis

Amino acid compositions of cell culture media are empirically designed to enhance cell growth and productivity and vary both across media formulations and over the course of culture due to imbalance in supply and consumption. The interconnected nature of the amino acid transporters and metabolism suggests that changes in amino acid composition can affect cell physiology. In this study, we explore the effect of a step change in amino acid composition from a DMEM: F12-based medium to a formulation varying in relative abundances of all amino acids, evaluated at two amino acid concentrations (lean LAA vs. rich HAA). Cell growth was inhibited in LAA but not HAA. In addition to the expected effects on expression of the cell cycle, amino acid response and mTOR pathway genes in LAA, we observed an unanticipated effect on zinc uptake and efflux genes. This was accompanied by a lower tolerance to zinc supplementation in LAA but not in the other formulations. Histidine was sufficient but not necessary to prevent such zinc toxicity. Additionally, an unanticipated downregulation of genes in the cholesterol synthesis pathway was observed in HAA, accompanied by an increase in cellular cholesterol content, which may depend on the relative abundances of glutamine and other amino acids. This study shows that changes in the amino acid composition without any evident effect on growth may have profound effects on metabolism. Such analyses can help rationalize the designing of medium and feed formulations for bioprocess applications beyond replenishment of consumed components.     

Hearing in laboratory animals: strain differences and nonauditory effects of noise

Hearing in laboratory animals is a topic that traditionally has been the domain of the auditory researcher. However, hearing loss and exposure to various environmental sounds can lead to changes in multiple organ systems, making what laboratory animals hear of consequence for researchers beyond those solely interested in hearing. For example, several inbred mouse strains commonly used in biomedical research (e.g., C57BL/6, DBA/2, and BALB/c) experience a genetically determined, progressive hearing loss that can lead to secondary changes in systems ranging from brain neurochemistry to social behavior. Both researchers and laboratory animal facility personnel should be aware of both strain and species differences in hearing in order to minimize potentially confounding variables in their research and to aid in the interpretation of data. Independent of genetic differences, acoustic noise levels in laboratory animal facilities can have considerable effects on the inhabitants. A large body of literature describes the nonauditory impact of noise on the biology and behavior of various strains and species of laboratory animals. The broad systemic effects of noise exposure include changes in endocrine and cardiovascular function, sleep-wake cycle disturbances, seizure susceptibility, and an array of behavioral changes. These changes are determined partly by species and strain; partly by noise intensity level, duration, predictability, and other characteristics of the sound; and partly by animal history and exposure context. This article reviews some of the basic strain and species differences in hearing and outlines how the acoustic environment affects different mammals.