Allergenicity evaluation of p-chloro-m-cresol and p-chloro-m-xylenol by non-radioactive murine local lymph-node assay and multiple-dose guinea pig maximization test

Contact sensitivity in patients with venous leg ulcer: A multi-centric Indian study

Venous leg ulcers are the most common form of non-healing leg ulcers. They are subjected to treatments such as topical medications, dressings, and compression therapies. This can lead to exposure to a number of allergens with subsequent sensitisation and contact dermatitis of the regional skin. This may contribute to the poor ulcer healing. To detect the various contact sensitisers in patients with venous leg ulcers through patch testing, patients from 6 centres across India with venous leg ulcers of longer than 6 weeks duration were enrolled for the study. They were patch tested using a special parch test kit with 27 antigens. A total of 172 patients were included in the study; 82 (48.2%) tested positive for at least 1 antigen. Among them, polyvalent sensitisation was noted in 71% of patients. Wood tar mix (10.4%) and the framycetin (8.7%) were the most common allergens. There is a high frequency of allergic sensitisation to various ingredients of topical therapies used in the venous ulcer management, which may interfere with wound healing. Avoiding them can help obtain a better therapeutic outcome.

Degradation of 4-Chloro-3,5-Dimethylphenol by a Heterogeneous Fenton-Like Reaction Using Nanoscale Zero-Valent Iron Catalysts

Degradation of 4-chloro-3,5-dimethylphenol (PCMX) by a heterogeneous Fenton-like process using nanoparticulate zero-valent iron (nZVI) and hydrogen peroxide (H2O2) at pH 6.3 was investigated. Interactive effects of three factors-initial PCMX concentration, nZVI dosage, and H2O2 concentration-were investigated using the response surface method based on the Box-Behnken design. Experimental results showed that complete decomposition of PCMX and 65% of total organic carbon removal were observed after 30 min of reaction at neutral pH under recommended reaction conditions: nZVI, 1.0 g/L; H2O2, 18 mM; and initial PCMX concentration, 0.15 g/L. Based on the effects of scavengers n-butanol and KI, removal of PCMX was mainly attributed to the attack of •OH, especially the surface-bonded •OH. A possible degradation pathway of PCMX was proposed.

A heterogeneous Fenton-like system with nanoparticulate zero-valent iron for removal of 4-chloro-3-methyl phenol

The removal of biocide 4-chloro-3-methyl phenol (CMP) was investigated by heterogeneous Fenton-like system using nanoparticulate zero-valent iron (nZVI) as catalyst. The properties of nZVI before and after reaction were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of pH value, initial concentration of CMP, nZVI dose and hydrogen peroxide (H(2)O(2)) concentration were determined. The experimental results showed that lower pH value and CMP concentration brought faster degradation rate. With the initial pH value of 6.1 and initial CMP concentration of 0.7 mM, the optimal dosage of reagents were 0.5 g nZVI/L and 3.0 mM H(2)O(2). At pH 6.1, the degradation of CMP followed two-stage first-order kinetic that composed of an induction period (first-stage) and a followed rapid degradation stage (second-stage). According to the effects of scavengers n-butanol and KI, hydroxyl radicals (OH), especially the surface-bounded •OH, had a dominant role in the oxidation of CMP. The degradation intermediates, carboxylic acids and chloride ion produced during the reaction process were monitored by high performance liquid chromatography (HPLC), liquid chromatography/mass spectrometry (LC/MS) and ion chromatography (IC). On the basis of these findings, the possible mechanistic steps of CMP degradation were proposed.

Evaluation of Allergenicity of Constituents of Myoga Using the Murine Local Lymph Node Assay

Myoga ( Zingiber Myoga Roscoe) is a perennial plant with a pungent smell from its flower buds. It is native to East Asia and has been reported to cause allergic contact dermatitis. The purpose of this study is to assess the allergenicity of myoga related to its major chemical components, α-pinene, β-pinene, limonene, limonene oxide and β-phellandrene, which are supposed to be the causative agents of contact dermatitis among myoga cultivators. We performed a toxicity study of the volatile constituents of myoga using the local lymph node assay (LLNA), in which limonene, limonene oxide and β-phellandrene had positive responses and the EC3 was 35.8%, 8.22%, and 0.54%, respectively. EC3 for both α-pinene and β-pinene was over 100%. Both chemicals failed to induce positive responses in the LLNA. While the maximization rating of limonene, limonene oxide and phellandrene were evaluated as moderate, extreme, and extreme respectively, α-pinene and β-pinene were evaluated as weak in the previously reported GPMT. The usage of LLNA was also confirmed by comparing with previously reported GPMT results to detect the allergenicity of myoga constituents. The actual risk of humans developing an allergy to myoga constituents depends on many factors. The concentration of the compounds, the frequency and duration of exposure and the condition of the skin are supposed to be important factors.

In conclusion, limonene, limonene oxide and β-phellandrene are constituents of myoga which revealed their allergenicity by the LLNA. The usefulness of the LLNA to detect the allergenicity of myoga constituents was also confirmed when considering the differences between the LLNA in the present study and the previously reported GPMT. The actual risk of humans developing an allergy to myoga constituents depends on many factors. The concentration of the compounds, the frequency and duration of exposure and condition of the skin are all important factors.

Degradation of the biocide 4-chloro-3,5-dimethylphenol in aqueous medium with ozone in combination with ultraviolet irradiation: operating conditions influence and mechanism

Biocides usually persist during municipal sewage treatment and are subsequently distributed into aquatic environments. To explore the capability of advanced oxidation processes for the rapid removal of biocides, we examined the total organic carbon (TOC) reduction of 4-chloro-3,5-dimethylphenol (PCMX) with a combination of UV/O(3). Moreover, the related important parameters, including the mass transfer coefficient and light utilization efficiency, in PCMX degradation were determined. The UV/O(3) experimental results showed a pronounced synergistic effect, leading to the nearly complete elimination of TOC within 75 min. Thus, the effect of operating variables was investigated as a function of pH, ozone dosage, bulk temperature and the initial concentration of PCMX. The efficiency of PCMX mineralization increased with an increase in ozone dose up to 3.1 gh(-1), and a decrease in the initial concentration from 250 to 100mg L(-1). The optimal pH value was 4.0, and the preferred bulk temperature was 20 degrees C on the basis of the influence of temperature on reaction rate and ozone solubility. The major aromatic intermediates identified by gas chromatography/mass spectrometry were 2,6-dimethylbenzene-1,4-diol, 2,6-dimethylbenzo-1,4-quinone, 2,6-bis(hydroxymethyl)benzo-1,4-quinone, and 2,6-dimethylbenzo-1,4-aldehyde. Quantitative determination of related carboxylic acid and inorganic anions was done by ion chromatography. On the basis of the identified reaction products, a possible degradation pathway for the UV/O(3) oxidation of PCMX in aqueous media is proposed.

Immunomodulatory effects of mono-, di-, and trimethylphenols in mice

The relationship of air pollutants with the increasing prevalence of allergic diseases is a matter of concern in developed countries. In this study, the immunomodulatory effects of mono-, di-, and trimethylphenols in mice were examined as regards two aspects. First, whether or not these chemicals act as sensitizers was evaluated by local lymph node assay. Of the 13 methylphenols tested, three dimethylphenol isomers (2,4-DMP, 2,5-DMP, and 3,4-DMP) were found to induce auricular lymphocyte proliferation after dermal application on both ears of mice. Cytokine production patterns in the supernatants of cultured auricular lymphocytes from mice showed these methylphenols to be contact sensitizers. Second, the effects of methylphenols on cytokine production profiles were examined using cultured splenocytes from immunologically naive mice. Under subtoxic conditions, eight methylphenols inhibited interferon-gamma (IFN-gamma) production significantly, while the effect on intreluekin-4 (IL-4) production was moderate, resulting in higher IL-4/IFN-gamma ratios in all of the tested chemicals, with the most prominent effect shown by 2,6-DMP. These results suggest that several methylphenols, especially dimethylphenol isomers, have potencies that affect the immune system, being immunogens themselves or modulators of the Th1/Th2 cytokine balance.

Allergenicity and cross-reactivity of naphthenic acid and its metallic salts in experimental animals

The allergenicity and the cross-reactivity of naphthenic acid (NA) and its metallic salts were evaluated in experimental animals. In the guinea pig maximization test, sensitizing skin reactions were observed with cobalt naphthenate (CoN), zinc naphthenate (ZnN) and NA, but not with copper naphthenate, with CoN being the most potent sensitizer. Animals sensitized with 1 naphthenic compound cross-reacted to the other 3 as well. Furthermore, animals in the CoN-sensitized group reacted to the relevant metallic salt cobalt chloride (CoCl2). A dose-response study using the CoN-sensitized group showed that the concentration of CoCl2 required to elicit a skin reaction of similar extent in comparison with CoN was more than 10 times higher, when skin-reaction scores were compared on the basis of cobalt content. In the local lymph node assay, significant increases in stimulation index values without skin irritation were observed with CoN and ZnN, where the former was more potent than the latter. Although CoN is a reported skin sensitizer, this study showed that skin allergenicity of naphthenic compounds is not restricted solely to CoN. In addition, the results suggest the main antigenic determinant of naphthenic compounds to be the structure of NA, even though metal moieties modulate their allergenicity.

Quantitative comparison of the results obtained by the multiple-dose guinea pig maximization test and the non-radioactive murine local lymph-node assay for various biocides

We compared the results of the multiple-dose guinea pig maximization test (GPMT) and the non-radioactive murine local lymph-node assay (LLNA) for various biocides. Thirteen out of 17 positive biocides in the GPMT gave positive results in the LLNA. In the GPMT, the minimum first induction doses ranged over four orders (0.00005-0.5%), while elicitation-threshold doses, which were evaluated using an optimally sensitized group of animals in the multiple-dose studies, ranged over five orders (0.00006-2.8%). In the LLNA, minimum induction doses ranged over more than three orders (0.01-30%). With respect to 13 biocides that were positive in both the GPMT and the LLNA, results were quantitatively compared. When compared after conversion to corresponding area doses (microg/cm), the minimum doses required to elicit skin reaction in guinea pigs were always lower than that for induction in mice with all biocides. Correlation between minimum induction doses from the GPMT and the LLNA seemed poor (r=0.57), while that between minimum induction doses in the LLNA and elicitation-threshold doses in the GPMT was relatively good (r=0.73). The results suggest the possibility to estimate human elicitation-threshold doses, which are definitely lacking in the process of risk assessment for skin-sensitizers, from the data of the LLNA.

Advantage of using CBA/N strain mice in a non-radioisotopic modification of the local lymph node assay

The murine local lymph node assay (LLNA) is currently recognized as a stand-alone test method for determining the skin sensitizing potential of chemicals. It has been incorporated into the official test guidelines published by some authorities, including the OECD. To avoid the use of radioisotopes, efforts have been made recently to develop non-radioisotopic modifications of the LLNA. A non-radioisotopic modification of the LLNA was developed previously using 5-bromo-2'-deoxyuridine (BrdU) incorporation (non-RI LLNA). However, the non-RI LLNA was found to be somewhat less sensitive than the standard assay. This study reports the advantage of using mice of the CBA/N strain in the non-RI LLNA to improve the sensitivity of this method. The non-RI LLNA was performed using CBA/JN and CBA/N mice exposed to one of four confirmed skin sensitizers, 2,4-dinitrochlorobenzene (DNCB), eugenol (EG), isoeugenol (IEG) or alpha-hexylcinnamic aldehyde (HCA), and to one non-sensitizer, propylene glycol (PG). The EC3 values for DNCB, IEG, EG, HCA and PG were calculated to be 0.1%, 9.6%, 40.6%, 45.5% and >50% in CBA/JN mice and 0.08%, 1.9%, 10.7%, 20.3% and >50% in CBA/N mice, respectively. The EC3 values for DNCB, IEG, EG, HCA and PG in the standard LLNA using CBA/Ca mice and radioisotopes were reported elsewhere as being 0.08%, 1.3%, 13.0%, 8.0% and >50%, respectively. The EC3 values derived from the CBA/N mice in the non-RI LLNA were nearly equivalent to the EC3 values obtained using the standard radioisotopic LLNA with CBA/Ca mice. These data suggest that the use of CBA/N mice may provide a realistic opportunity to develop a version of the LLNA that does not have a requirement for the use of radioisotopes, but which nevertheless has sensitivity approaching, or comparable to, the standard method.

Allergenicity evaluation of Bioban CS-1135 in experimental animals

An industrial preservative, Bioban CS-1135, was evaluated for its contact allergenicity by means of multiple-dose guinea-pig maximization test and non-radioactive murine local lymph node assay. In the guinea-pig test, an induction dose of 0.5% Bioban CS-1135 sensitized all animals of the group. The dose-response study of the elicitation phase determined a minimum elicitation dose of 5% for positive skin reactions. In the murine assay, Bioban CS-1135 at doses of 10% and more exerted significant effects on lymphoid cell proliferation. Although the data clearly designated Bioban CS-1135 as a skin sensitizer, its relative potency was ranked lowest among skin-sensitizing biocides previously evaluated in this laboratory.