Evaluation of percutaneous penetration of natural rubber latex proteins

Decontamination of Actinide-contaminated Injured Skin with Ca-DTPA Products Using an Ex Vivo Rat Skin Model

ABSTRACT

Skin contamination by α-emitting actinides such as plutonium and americium is a risk for workers during nuclear fuel production and reactor decommissioning. Decontamination of skin is an important medical countermeasure to limit potential internal contamination, particularly in the case of injured skin. Current recommendations include undressing of the victim followed by skin washing using soap or chelating agents, such as diethylene triamine pentaacetic acid (DTPA). The goal of the present work is to assess the efficacy of a novel Ca-DTPA loaded gel to decontaminate injured skin exposed to plutonium or americium as compared to recommended treatments. For decontaminant testing on injured skin, whole body skin was obtained from euthanized rats and lesions created using a metallic brush. Delimited test areas were contaminated with plutonium or americium solutions of known properties. Various protocols were tested including time before contamination, duration of gel application, washing steps, as well as the concomitant addition or not of dressings. Activity was measured in each decontamination product and in skin. Data indicate that healthy skin was easier to decontaminate than damaged skin. On injured skin, we demonstrated an increased decontamination efficacy of the Ca-DTPA gel formulation as compared to the solution. Importantly, gel application alone was effective, and further gel applications could be used for residual activity.

Lipopolysaccharide interferes with the use of the human Cell Line Activation Test to determine the allergic potential of proteins

It was believed that high molecular weight molecules including proteins cannot penetrate the skin. However, protein penetration through disrupted/ruptured skin has been reported recently, thus carrying the potential for inducing an allergic response. We used the human Cell Line Activation Test (h-CLAT), an in vitro skin sensitization test, to assess the allergic potential of proteins by measuring levels of CD86 and CD54 in the human monocytic leukemia cell line THP-1. Six allergens including ovalbumin (OVA) and human serum albumin (HSA; negative control) upregulated CD86 and/or CD54; a false-positive result was obtained using HSA. This was caused by lipopolysaccharide (LPS) contamination. Naturally derived materials often include LPS at various concentrations and may influence protein induction of CD86 and CD54. Additionally, polymyxin B, an LPS inhibitor, could not completely overcome the effect of LPS. Therefore, if test proteins contain ≥0.1 EU/mL LPS, their allergenic potency will not be assessed accurately using h-CLAT. These data show that naturally occurring materials or those derived from living organisms should be evaluated for their LPS content. It is important to confirm the applicability of in vitro methods such as h-CLAT for assessing the allergenic potency of naturally occurring proteins; our findings can be a foundation for future studies.

Potential health effects associated with dermal exposure to occupational chemicals

There are a large number of workers in the United States, spanning a variety of occupational industries and sectors, who are potentially exposed to chemicals that can be absorbed through the skin. Occupational skin exposures can result in numerous diseases that can adversely affect an individual's health and capacity to perform at work. In general, there are three types of chemical-skin interactions of concern: direct skin effects, immune-mediated skin effects, and systemic effects. While hundreds of chemicals (metals, epoxy and acrylic resins, rubber additives, and chemical intermediates) present in virtually every industry have been identified to cause direct and immune-mediated effects such as contact dermatitis or urticaria, less is known about the number and types of chemicals contributing to systemic effects. In an attempt to raise awareness, skin notation assignments communicate the potential for dermal absorption; however, there is a need for standardization among agencies to communicate an accurate description of occupational hazards. Studies have suggested that exposure to complex mixtures, excessive hand washing, use of hand sanitizers, high frequency of wet work, and environmental or other factors may enhance penetration and stimulate other biological responses altering the outcomes of dermal chemical exposure. Understanding the hazards of dermal exposure is essential for the proper implementation of protective measures to ensure worker safety and health.

The prevalence of latex sensitisation and allergy and associated risk factors among healthcare workers using hypoallergenic latex gloves at King Edward VIII Hospital, KwaZulu-Natal South Africa: a cross-sectional study

OBJECTIVES

The present study describes latex sensitisation and allergy prevalence and associated factors among healthcare workers using hypoallergenic latex gloves at King Edward VIII Hospital in KwaZulu-Natal, South Africa.

DESIGN

Cross-sectional study.

SETTING

A tertiary hospital in eThekwini municipality, KwaZulu-Natal, South Africa.

PARTICIPANTS

600 healthcare workers were randomly selected and 501 (337 exposed and 164 unexposed) participated. Participants who were pregnant, with less than 1 year of work as a healthcare worker and a history of anaphylactic reaction were excluded from the study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Latex sensitisation and latex allergy were the outcome of interest and they were successfully measured.

RESULTS

The prevalence of latex sensitisation and allergy was observed among exposed workers (7.1% and 5.9%) and unexposed workers (3.1% and 1.8%). Work-related allergy symptoms were significantly higher in exposed workers (40.9%, p<0.05). Duration of employment was inversely associated with latex allergy (OR 0.9; 95% CI 0.8 to 0.9). The risk of latex sensitisation (OR 4.2; 95% CI 1.2 to 14.1) and allergy (OR 5.1; 95% CI 1.2 to 21.2) increased with the exclusive use of powder-free latex gloves. A dose-response relationship was observed for powdered latex gloves (OR 1.1; 95% CI 1.0 to 1.2). Atopy (OR 1.5; 95% CI 0.7 to 3.3 and OR 1.4; 95% CI 0.6 to 3.2) and fruit allergy (OR 2.3; 95% CI 0.8 to 6.7 and OR 3.1; 95% CI 1.1 to 9.2) also increased the risk of latex sensitisation and allergy.

CONCLUSIONS

This study adds to previous findings that healthcare workers exposed to hypoallergenic latex gloves are at risk for developing latex sensitisation highlighting its importance as an occupational hazard in healthcare. More research is needed to identify the most cost effective way of implementing a latex-free environment in resource-limited countries, such as South Africa. In addition more cohort analysis is required to better understand the chronicity of illness and disability associated with latex allergy.

Absorption of chemicals through compromised skin

Skin is an important route of entry for many chemicals in the work place. To assess systemic uptake of a chemical in contact with the skin, quantitative information on dermal absorption rates of chemicals is needed. Absorption rates are mainly obtained from studies performed with intact, healthy skin. At the work place, however, a compromised skin barrier, although not necessarily visible is common, e.g. due to physical and chemical damage. As reviewed in this article, there are several lines of evidence that reduced integrity of the skin barrier may increase dermal absorption of chemicals in the occupational setting. An impaired skin barrier might lead not only to enhanced absorption of a specific chemical, but also to entrance of larger molecules such as proteins and nanoparticles which normally are not able to penetrate intact skin. In addition to environmental influences, there is increasing evidence that some individuals have an intrinsically affected skin barrier which will facilitate entrance of chemicals into and through the skin making these persons more susceptible for local as well for systemic toxicity. This review addresses mechanisms of barrier alteration caused by the most common skin-damaging factors in the occupational settings and the consequences for dermal absorption of chemicals. Furthermore, this review emphasizes the importance of maintained barrier properties of the skin.

Enhancement of transdermal fentanyl and buprenorphine antinociception by transdermal Δ9-tetrahydrocannabinol

Previous studies have demonstrated that delta9-tetrahydrocannabinol (THC) enhances the antinociceptive potency of many opioids administered by a variety of different routes of administration. We hypothesized that THC would enhance fentanyl or buprenorphine analgesia via the transdermal route of administration. THC was first demonstrated to enhance opioid antinociception when both drugs were administered parenterally in a hairless guinea pig model using the pin prick test. A low dose of THC (50 mg/kg, i.p.) produced no antinociception. However, THC enhanced the potency of s.c. fentanyl by 6.7-fold, and s.c. buprenorphine in a non-parallel fashion. For the transdermal studies, THC, fentanyl or buprenorphine was applied by pipette to the skin of the dorsum between the fore- and hind-flanks and covered with individual Tegederm patches. THC (400 mg/kg) produced no antinociception. However, THC enhanced fentanyl's potency by 3.7-fold at 2-h, and 5.8-fold at 4-h. Buprenophine's potency was increased 8.2-fold at 2-h and 7.2-fold at 4-h when co-administered with THC. These results indicate that the enhancement of transdermal opioids by THC could lead to the design of an effective combination analgesic patch.

Isocyanates, polyurethane and childhood asthma

Isocyanates are the most prominent and well-studied cause of occupational asthma. Over the decades, airborne isocyanates have been regulated to extremely low levels in the workplace, some of the lowest for any organic compound. Yet the incidence of isocyanate-induced occupational asthma remains high and the role of dermal exposure in disease etiology is only slowly being recognized. Almost completely overlooked is the potential relationship between isocyanates in consumer products and increasing prevalence of asthma in the general population, especially children. The steady rise in asthma over the past decades points strongly to a potential role of environmental exposures in its development. Imbalances in the immune system favoring respiratory diseases have been linked to biological and chemical stressor exposures early in life. Evidence for the presence of isocyanates in many polyurethane-containing materials, especially polyurethane foams, is presented as a possible contributor to the increase in asthma. Polyurethane foam is ubiquitous in western societies and used in bedding, furniture, automobile seats, footwear, etc., and numerous medical materials. Theoretical, epidemiologic, experimental and clinical evidence of a role for isocyanates and polyurethanes in the genesis of non-occupational allergy and respiratory disease are reviewed. These data all point to the urgent need for additional research on the links between isocyanates, polyurethanes and the role of the skin in non-occupational asthma.

Occupation-related allergies in dentistry

BACKGROUND

Allergies to natural rubber latex (NRL) were unknown in dentistry until 1987. That changed with the publication of a report documenting NRL-based anaphylaxis in a dental worker. This case and others prompted regulatory and manufacturing changes in rubber products and increased awareness throughout the profession. However, other common dental chemicals cause allergic reactions and irritation and often are handled with insufficient precautions. Although recognition of NRL allergy has improved, awareness of other potential allergens and irritants in dentistry still is limited.

OVERVIEW

Recent research indicates that the prevalence of NRL protein allergy may be decreasing. In contrast, occupation-related dermatoses associated with other dental products may be more common. Encounters with bonding agents, disinfectants, rubber, metals and detergents can cause occupation-based irritant contact dermatitis and allergic contact dermatitis. These conditions may be found in more than one-quarter of dental and medical personnel. Therefore, dental-specific information about the recognition and management of allergic and irritant reactions is needed.

CONCLUSIONS AND CLINICAL IMPLICATIONS

The prevalence of occupation-related dermatitis may be increasing in dentistry. Reducing exposure to potential irritants and allergens and educating personnel about proper skin care are essential to reversing this trend.

Latex allergy

The prevalence of IgE mediated natural latex rubber allergy is estimated to be < 1% in the general population, < 17% in medical personnel and approximately 0% in children with spina bifida. We review the definition, diagnosis, prevention, and treatment of NLR allergy.

Cataract surgery for natural rubber latex allergic patients

The prevalence of reactions against natural rubber latex (NRL) is thought to be increasing in both the general public and healthcare workers. These can vary from mild benign skin reactions to bronchospasm, anaphylactic shock, and death. Difficulties exist for ophthalmic departments wishing to establish protocols in providing 'latex-free environments' for patients undergoing cataract surgery. Currently no legislation exists regarding the labelling of NRL-containing products in the United Kingdom with information on a product's NRL content provided by the manufacturer on a voluntary basis only. It is hoped this review article will act as a basic guide in the management of NRL-sensitive patients undergoing cataract surgery in the United Kingdom.

Allergic and latex-specific sensitization: route, frequency, and amount of exposure that are required to initiate IgE production

Quantitative data that documents human exposure-response relationships for IgE sensitization to allergens are limited. Although seemingly straightforward, documentation of exposure-response relationships can be difficult. Issues that are related to study design, allergen standardization, exposure assessment, and evaluation for sensitization can impact greatly on study results. Despite these issues, exposure-response relationships for sensitization to protein allergens have been documented in several occupational groups, which include enzyme-detergent workers, bakers, and laboratory animal workers. In general, atopy acts as an effect modifier in these settings, steepening the exposure-response relationship. Several studies suggest that the greatest risk for sensitization is within the first several years of exposure. For 1 allergen, the protease subtilisin, a short-term exposure limit of 60 ng/m(3) has been recommended by the American Council of Governmental Industrial Hygienists. With regard to natural rubber latex, exposure-related factors such as number of operations have been shown to be risk factors for sensitization of children with spina bifida. By contrast, fewer studies show exposure-response relationships for IgE sensitization of health care workers to natural rubber latex, and the area remains controversial. However, a recent cohort study that evaluated incident sensitization in dental hygiene students suggests strongly that, with sufficient exposure, employment in health care can lead to an increased risk of IgE sensitization to natural rubber latex.

Murine models for natural rubber latex allergy assessment

Murine models provide a powerful tool in the investigation of latex allergy and the development of intervention strategies. The immune responses to protein allergens of mice and humans are similar but differences related to the roles of IgE and IgG must be recognized. Mice have been shown to mount a dose and time-dependent IgE response to latex proteins following topical, respiratory, and subcutaneous exposures. Methods are available to evaluate cutaneous and respiratory responses to latex challenge in sensitized animals. These models have been used to investigate the role of route of exposure on the development of latex allergy and to provide a means for investigating the contribution of individual proteins to adverse respiratory and dermal responses. These models provide a mechanism for the evaluation of new technologies aimed at reducing the allergenicity of latex products, and for testing for the potential for cross-reactivity to new allergens in previously sensitized individuals. Murine models may also provide a method for testing immunotherapy strategies prior to initiating human trials.

Latex allergy: past and present

Although latex products have been in use for over a century, allergic responses to latex proteins have only been recognized as a serious health problem for the past 15 years. Latex allergy particularly affects two groups, health care workers (HCW) and children with spina bifida (SB). This manuscript provides a brief history of latex allergy, and a review of the following: the manufacturing process for dipped latex products, the 11 latex allergens that have been characterized and received allergen designations by the International Union of Immunological Societies, the methods used in exposure assessment, the epidemiology and clinical management of latex allergy, and the use of animal models in investigating mechanisms underlying latex allergy.

Latex allergy: review of recent advances

Latex allergy is an IgE-dependent immediate hypersensitivity reaction to latex proteins. Risk factors for latex allergy are contact with latex products and atopy. Children who undergo multiple surgical procedures and healthcare workers are the major groups at risk. Powdered latex gloves are an important source of sensitization. Preventive measures are leading to reduction in latex sensitization and allergic reactions. The prevalence of latex allergy in the general population may be as low as 0.1%, whereas the frequency of latex sensitization is reported to be 7%; this may be due to cross-reacting antipollen IgE. The most important latex allergens have been purified, and some have been cloned and sequenced. Many latex-allergic patients are also allergic to common plant-derived aeroallergens and foods. The structural and biologic relationships among plant-derived food allergens, including latex, explain these clinically important cross-reactions.