Occupational risks of (meth)acrylate compounds in embedding media for electron microscopy

Cognitive Functioning and Nail Salon Occupational Exposure among Vietnamese Immigrant Women in Northern California

Introduction: Vietnamese nail salon technicians are continuously exposed to neurotoxins linked to cognitive impairments and Alzheimer’s disease. This study examined the association of occupational exposure with cognitive function and depressive symptoms among Vietnamese nail salon technicians. Methods: The sample included 155 current or former Vietnamese female nail technicians and 145 control group participants. Measures included the Montreal Cognitive Assessment (MoCA) and the Center for Epidemiologic Studies Depression Scale (CES-D). Results: Average cognitive functioning was significantly higher for the control compared to the nail technician group (mean difference = 1.2, p < 0.05). No differences were observed for depression. Multivariate findings revealed that exposure was negatively associated with cognitive functioning (β = −0.29, 95% CI: −0.53, −0.05, p < 0.05). Discussion: Nail salon work and the extent of occupational exposure were associated with lower cognitive functioning among Vietnamese nail technicians. Longitudinal research can further examine the risk for cognitive decline and dementia for this vulnerable population.

Combining high-pressure freezing with pre-embedding immunogold electron microscopy and tomography

Immunogold labeling of permeabilized whole-mount cells or thin-sectioned material is widely used for the subcellular localization of biomolecules at the high spatial resolution of electron microscopy (EM). Those approaches are well compatible with either 3-dimensional (3D) reconstruction of organelle morphology and antigen distribution or with rapid cryofixation-but not easily with both at once. We describe here a specimen preparation and labeling protocol for animal cell cultures, which represents a novel blend of specifically adapted versions of established techniques. It combines the virtues of reliably preserved organelle ultrastructure, as trapped by rapid freezing within milliseconds followed by freeze-substitution and specimen rehydration, with the advantages of robust labeling of intracellular constituents in 3D through means of pre-embedding NANOGOLD-silver immunocytochemistry. So obtained thin and semi-thick epoxy resin sections are suitable for transmission EM imaging, as well as tomographic reconstruction and modeling of labeling patterns in the 3D cellular context.

Correlative light and electron microscopy using immunolabeled sections

In correlative microscopy, light microscopy provides the overview and orientation of the complex cells and tissue, while electron microscopy offers the detailed localization and correlation of subcellular structures. In this chapter we offer detailed high-quality electron microscopical preparation methods for optimum preservation of the cellular ultrastructure. From such preparations serial thin sections are collected and used for comparative histochemical, immunofluorescence, and immunogold staining.In light microscopy histological stains identify the orientation of the sample and immunofluorescence labeling facilitates to find the region of interest, namely, the labeled cells expressing the macromolecule under investigation. Sections, labeled with immunogold are analyzed by electron microscopy in order to identify the label within the cellular architecture at high resolution.

Correlative light and electron microscopy using immunolabeled resin sections

In correlative microscopy, light microscopy provides the overview and orientation in the complex cells and tissue, whereas electron microscopy offers the detailed localization and correlation to subcellular structures. In this chapter, we offer the detailed high-quality electron microscopical preparation methods for the optimum preservation of the cellular ultrastructure. From such preparations, serial thin sections are collected and used for comparative histochemical, immunofluorescence, and immunogold staining. In light microscopy, histological stains are used to identify the orientation of the sample, and immunofluorescence labeling is used to identify the region of interest, namely, the labeled cells expressing the macromolecule under investigation. Subsequent sections, labeled with immunogold, are analyzed by electron microscopy to identify the label within the cellular architecture at high resolution.

Cross-reactivity patterns of contact-sensitizing methacrylates

Methacrylates are well-known contact sensitizers with increasing frequency of contact leading to occupational skin disease. Here, we developed an animal model to facilitate studies on the sensitizing capacities and cross-reactivity patterns between four clinically most important allergens: methacrylate (MMA), 2-hydroxyethyl methacrylate (2-HEMA), 2-hydroxypropyl methacrylate (2-HPMA) and ethyleneglycol dimethacrylate (EGDMA). Inbred guinea pigs were immunized by ic injections of 300 microliters of 1.0 M methacrylate solutions in Freund's complete adjuvant into both flanks, both ears, and the neck. After 14 days open skin tests were performed with 50% MMA, 2-HEMA, or 2-HPMA or 10% EGDMA solutions in 40% DMSO in ethanol. Cross-reactivities were investigated 14 days later by skin testing with all four methacrylates. Using this newly developed protocol, strongly positive skin tests for methacrylates could be induced in almost all guinea pigs (MMA 26/26, 2-HEMA 16/18, 2-HPMA 15/16 and EGDMA 11/11). Whereas EGDMA induced only weak or infrequent cross-reactivities, 2-HEMA sensitization led to strong cross-reactions to all other methacrylates. Both MMA and 2-HPMA induced strong cross-reactivity to EGDMA but only weak to moderate reactivities to the other methacrylates. The absence of strong cross-reactions with monomethacrylates in EGDMA (dimethacrylate)-sensitized animals may be explained by the predominance of highly EGDMA-specific T-cells in these animals. In contrast, sensitization with MMA, 2-HEMA, and 2-HPMA would lead to recruitment of T-cells cross-reactive to the other monomethacrylates, according to their molecular similarities. The strong skin hypersensitivities observed for EGDMA in these latter groups are ascribed to enzymatic degradation into monomethacrylate compounds, notably 2-HEMA, at a rate sufficient to elicit cognate effector T-cells. The results of this study offer new insights in the development of methacrylate hypersensitivities and common cross-sensitization patterns in clinical practice.

What's new in managing health hazards in pathology departments

Health hazards related to activities performed in pathology departments have represented, in recent years, an increasing concern among pathologists and pathology technicians. The major occupational health problems encountered in pathology departments are reviewed. They include biological hazards (tuberculosis, hepatitis, HIV, other infectious diseases), chemical hazards (formaldehyde, xylene(s), aromatic amines, methacrylates, glutaraldehyde, latex) and physical hazards (cut injuries, accidental fires, radiation). Current data suggest that infections (particularly, tuberculosis and hepatitis) still represent the more relevant risk. Exposure to HIV and Creutzfeldt-Jakob agent may be highly harmful but containment measures have been proven to be effective. The actual adverse effects due to chemicals seem to be less alarming than was previously believed. Attaining a safe work environment is an inherent element of good quality assurance management. This task is largely a matter of information, education, organization and common sense. Well-designed premises, efficient equipment and well-trained personnel are the keys to preventing and minimizing hazardous exposures. In order to provide current information that may be used by pathology staff to implement the functional quality of the workplace, organizational and preventive measures are described.

Cryofixation, cryosubstitution, cryoembedding for ultrastructural, immunocytochemical and microanalytical studies

Cryofixation, cryosubstitution and cryoembedding are a set of low-temperature methods for immunocytochemical and microanalytical ultrastructural studies. This review covers the theoretical and practical aspects of these cryomethods, simple, low-cost, safe devices that provide reproducible results and a summary of recent results. Sections prepared by these three cryomethods can be used to determine elemental composition, molecular composition, functions and 3-D ultrastructure. The information obtained can be treated by multivariate statistical methods. Thus, each cellular compartment can be identified by its morphology, molecular and elemental composition and function and changes in these data during physiological and pathological processes can be monitored.

A glove with exceptional protective features minimizes the risks of working with hazardous chemicals

In continuation of our preceding studies, we disclose long-term experiments to test more extensively the protective power of the novel 4H Glove. 2 compounds encountered in modern electron microscopy technique, 1-hexadecene (1-HD) and 2-hydroxyethyl acrylate (2-HEA), which elicit allergic and/or toxic reactions in laboratory workers, were tested for their penetration through the 4H Glove material 1-HD has not to our knowledge been tested on any glove material. 2-HEA was known to have a breakthrough time exceeding 240 min; in contrast, it penetrates the common latex or vinyl gloves within minutes. When exposing the outside of a 4H Glove to 2-HEA for 200 h at 21 degrees C and then attaching the reverse unexposed side to a sensitized volunteer's forearm, 30 min of contact elicited a barely visible reddening of the skin at the contact site which disappeared within 24 h; 90 min of contact caused a somewhat stronger reddening limited to the contact area, which disappeared within 2 days. By the same criteria, 1-HD did not penetrate through the 4H Glove in 200 h. In an additional experiment, breakthrough time of 1-HD on latex gloves was less than 30 min.