Guinea Pig Skin Research Articles

Sulfur mustard-induced apoptosis in hairless guinea pig skin.

The present study was aimed to examine whether apoptosis is involved in the pathogenesis of sulfur mustard (SM)-induced basal cell death. Skin sites of the hairless guinea pig exposed to SM vapor for 8 minutes were harvested at 3, 6, 12, 24, and 48 hours postexposure. Immunohistochemical detection of basal cell apoptosis was performed using the ApopTag in situ apoptosis labeling kit. Only occasional apoptotic basal cells (BC)were observed in nonexposed and perilesional control sites. At lesional sites, apoptosis of BC was not detected at 3 hours postexposure. However, at 6 hours and 12 hours postexposure, 18% and 59% of BC were apoptotic, respectively. At 24 and 48 hours postexposure, individual apoptotic basal cells were not clearly recognizable due to necrosis. At the ultrastructural level, degenerating BC exhibited typical apoptotic morphology including nuclear condensation and chromatin margination. The results suggest that apoptotic cell death is a cytotoxic mechanism with the number of BC undergoing apoptosis significantly increasing from 6 to 12 hours postexposure. In addition, because necrosis is preferential at 24 hours postexposure, we believe that SM-induced cell death involves early apoptosis and late necrosis, which temporally overlap to produce a single cell death pathway along an apoptotic-necrotic continuum.

Acrylate-Based Transdermal Therapeutic System of Nitrendipine

The objective of the present research investigation was to fabricate an acrylate-based transdermal therapeutic system (TTS) of nitrendipine, which could deliver drug at maximum input rate so as to deliver drug in minimum patch size. Transdermal patches were fabricated using synthesized acrylate pressure-sensitive adhesives (PSAs): PSA1, PSA2, and commercially available PSA3 and PSA4 using d-limonene as permeation enhancer. Effect of concentration of d-limonene on permeation kinetics of nitrendipine in PSAs was studied. Fabricated TTS in mentioned PSAs were evaluated for in-vitro release and permeation kinetics through guinea-pig skin. Cumulative release of drug in PSA1, PSA2, PSA3, and PSA4 was observed to be 45%, 40%, 25%, and 25%, respectively, upto 24 hr. Flux of drug through guinea-pig skin calculated at 48 hr in PSA1, PSA2, PSA3, and PSA4, with and without d-limonene, was observed to be 0.346 ± 0.10, 0.435 ± 0.17, 0.410 ± 0.17, and 0.162 ± 0.06, and 0.625 ± 0.19, 1.161 ± 0.46, 0.506 ± 0.17, and 0.520 ± 0.18 (µg/cm2/hr), respectively. The TTS in PSA2 showed comparatively high flux and could deliver drug at high input rate through transdermal route. PSA2 was found to have good rate-controlling property and could be successfully employed in transdermal delivery of nitrendipine.

LECITHIN-STABILIZED MICROEMULSION-BASED ORGANOGELS FOR TOPICAL APPLICATION OF KETOROLAC TROMETHAMINE. II. IN VITRO RELEASE STUDY

Ketorolac tromethamine (KT) containing microemulsion-based gels (MBGs) have been formulated, based on the previous phase diagram studies, using a pharmaceutically acceptable surfactant (soybean lecithin; Epikuron 200) and oil (isopropyl myristate; IPM) and the effect of formulation variables on the release profile of the drug from MBGs through intact guinea pig skin and various artificial membranes was then determined experimentally. It was observed that as the lecithin concentration increased from 40 to 50 and then 60% w/w in formulations, a significant decrease in KT release was obtained. A remarkable increase in the drug release was also observed in formulations containing 6.5% w/w of KT compared to those containing 1% w/w of the drug. Increasing the water content of the organogels also resulted in an increase in KT release. The optimized formulation of the organogel composed of 40% lecithin and 60% IPM (containing 0.6% w/w of water and 6.5% w/w of KT) showed the highest drug release rate. Moreover, the viscosity of different formulations and their rheological behavior were also determined. All formulations showed a slightly rheopexic behavior. It was found that an increase in lecithin concentration resulted in an increase in the viscosity of the organogel. Results have shown that KT could be incorporated at high concentrations into lecithin organogels and these systems could be considered as desirable drug delivery vehicles for water soluble drugs and are capable of providing an appropriate drug release rate and pattern.

An aspirin-triggered lipoxin A4 stable analog displays a unique topical anti-inflammatory profile.

Lipoxins and 15-epi-lipoxins are counter-regulatory lipid mediators that modulate leukocyte trafficking and promote the resolution of inflammation. To assess the potential of lipoxins as novel anti-inflammatory agents, a stable 15-epi-lipoxin A(4) analog, 15-epi-16-p-fluorophenoxy-lipoxin A(4) methyl ester (ATLa), was synthesized by total organic synthesis and examined for efficacy relative to a potent leukotriene B(4) (LTB(4)) receptor antagonist (LTB(4)R-Ant) and the clinically used topical glucocorticoid methylprednisolone aceponate. In vitro, ATLa was 100-fold more potent than LTB(4)R-Ant for inhibiting neutrophil chemotaxis and trans-epithelial cell migration induced by fMLP, but was approximately 10-fold less potent than the LTB(4)R-Ant in blocking responses to LTB(4). A broad panel of cutaneous inflammation models that display pathological aspects of psoriasis, atopic dermatitis, and allergic contact dermatitis was used to directly compare the topical efficacy of ATLa with that of LTB(4)R-Ant and methylprednisolone aceponate. ATLa was efficacious in all models tested: LTB(4)/Iloprost-, calcium ionophore-, croton oil-, and mezerein-induced inflammation and trimellitic anhydride-induced allergic delayed-type hypersensitivity. ATLa was efficacious in mouse and guinea pig skin inflammation models, exhibiting dose-dependent effects on edema, neutrophil or eosinophil infiltration, and epidermal hyperproliferation. We conclude that the LXA(4) and aspirin-triggered LXA(4) pathways play key anti-inflammatory roles in vivo. Moreover, these results suggest that ATLa and related LXA(4) analogs may have broad therapeutic potential in inflammatory disorders and could provide an alternative to corticosteroids in certain clinical settings.

Species variations in cutaneous alcohol dehydrogenases and aldehyde dehydrogenases may impact on toxicological assessments of alcohols and aldehydes

Alcohol dehydrogenase (ADH; EC. 1.1.1.1) and aldehyde dehydrogenase (ALDH; EC 1.2.1.3) play important roles in the metabolism of both endogenous and exogenous alcohols and aldehydes. The expression and localisation patterns of ADH (1–3) and ALDH (1–3) were investigated in the skin and liver of the mouse (BALB/c and CBA/ca), rat (F344) and guinea-pig (Dunkin-Hartley), using Western blot analysis and immunohistochemistry with class-specific antisera. ALDH2 expression and localisation was also determined in human skin, while ethanol oxidation, catalysed by ADH, was investigated in the mouse, guinea-pig and human skin cytosol. Western blot analysis revealed that ADH1, ADH3, ALDH1 and ALDH2 were expressed, constitutively, in the skin and liver of the mouse, rat and guinea-pig. ADH2 was not detected in the skin of any rodent species/strain, but was present in all rodent livers. ALDH3 was expressed, constitutively, in the skin of both strains of mouse and rat, but was not detected in guinea-pig skin and was absent in all livers. Immunohistochemistry showed similar patterns of expression for ADH and ALDH in both strains of mouse, rat, guinea-pig and human skin sections, with localisation predominantly in the epidermis, sebaceous glands and hair follicles. ADH activity (apparent V max, nmoles/mg protein/min) was higher in liver (6.02–16.67) compared to skin (0.32–1.21) and lower in human skin (0.32–0.41) compared to mouse skin (1.07–1.21). The ADH inhibitor 4-methyl pyrazole (4-MP) reduced ethanol oxidation in the skin and liver in a concentration dependent manner: activity was reduced to ≈30–40% and ≈2–10% of the control activity, in the skin and liver, respectively, using 1 mM 4-MP. The class-specific expression of ADH and ALDH enzymes, in the skin and liver and their variation between species, may have toxicological significance, with respect to the metabolism of endogenous and xenobiotic alcohols and aldehydes.

Depigmenting action of phenylhydroquinone, an O-phenylphenol metabolite, on the skin of JY-4 black guinea-pigs.

The effects of o-phenylphenol (OPP) and its metabolite, phenylhydroquinone (PHQ) on the skin of JY-4 black guinea-pigs were studied. Topical application of 1 or 5% PHQ on the black skin of the back caused marked depigmentation and hypopigmentation of the skin after 5 weeks, whereas OPP applied at the same concentrations had little effect. Depigmented skin had an increased L* (lightness) value in the CIE-L*a*b* color system. This corresponded with a decreased number of melanocytes and melanosomes in the melanocytes and keratinocytes, the disruption of melanosomes in the melanocytes, and destruction of the membranous organelles of the melanocytes. These morphological and numerical changes in epidermal melanocytes indicate that selective melanocyte toxicity occurred. Furthermore, application of PHQ to the skin of white guinea-pigs caused skin irritation, as shown by a colorimetric increase in a* value (redness) and by histological observation of inflammation. This study confirmed that OPP, which is a reported depigmenter, has little depigmenting action, while its metabolite, PHQ, is a potent depigmenter preferentially affecting melanocytes.

Cutting balloon angioplasty for aorto-ostial lesions

Alcohol dehydrogenase (ADH; EC. 1.1.1.1) and aldehyde dehydrogenase (ALDH; EC 1.2.1.3) play important roles in the metabolism of both endogenous and exogenous alcohols and aldehydes. The expression and localisation patterns of ADH (1–3) and ALDH (1–3) were investigated in the skin and liver of the mouse (BALB/c and CBA/ca), rat (F344) and guinea-pig (Dunkin-Hartley), using Western blot analysis and immunohistochemistry with class-specific antisera. ALDH2 expression and localisation was also determined in human skin, while ethanol oxidation, catalysed by ADH, was investigated in the mouse, guinea-pig and human skin cytosol. Western blot analysis revealed that ADH1, ADH3, ALDH1 and ALDH2 were expressed, constitutively, in the skin and liver of the mouse, rat and guinea-pig. ADH2 was not detected in the skin of any rodent species/strain, but was present in all rodent livers. ALDH3 was expressed, constitutively, in the skin of both strains of mouse and rat, but was not detected in guinea-pig skin and was absent in all livers. Immunohistochemistry showed similar patterns of expression for ADH and ALDH in both strains of mouse, rat, guinea-pig and human skin sections, with localisation predominantly in the epidermis, sebaceous glands and hair follicles. ADH activity (apparent Vmax, nmoles/mg protein/min) was higher in liver (6.02–16.67) compared to skin (0.32–1.21) and lower in human skin (0.32–0.41) compared to mouse skin (1.07–1.21). The ADH inhibitor 4-methyl pyrazole (4-MP) reduced ethanol oxidation in the skin and liver in a concentration dependent manner: activity was reduced to ≈30–40% and ≈2–10% of the control activity, in the skin and liver, respectively, using 1 mM 4-MP. The class-specific expression of ADH and ALDH enzymes, in the skin and liver and their variation between species, may have toxicological significance, with respect to the metabolism of endogenous and xenobiotic alcohols and aldehydes.

Skin toxicokinetics of mustard gas in the guinea pig: effect of hypochlorite and safety aspects.

Sulfur mustard (SM, mustard gas) is a chemical warfare vesicant that rapidly penetrates the skin due to its hydrophobicity. This study measured the rate of SM disappearance from the skin after topical application of the vesicant. In both fur-covered and hairless animals, the remaining toxicant levels measured 60 min after exposure to undiluted SM were 0.6% and 0.3%, respectively, of the initially applied SM amount. However, SM concentration reached 0.4% of the initial dose 3 h following exposure in female fur-covered guinea pigs. SM quantities extracted from skin of male fur-covered and hairless guinea pigs immediately after 16 min of exposure to SM vapor were 12.2 and 21.8 microg, respectively; levels declined to 1.6 and 1.7 microg at 30 and 15 min following termination of exposure of male fur-covered and hairless guinea pigs, respectively. Three swabbing treatments of undiluted SM-exposed skin with gauze pads soaked in 0.5% hypochlorite caused 68% reduction in skin SM content. Similar findings were obtained when hypochlorite was replaced by water (64% reduction). SM content in the gauze pads was 59, 38 and 25 microg, respectively, for the first, second and third decontamination processes with water. No SM was detected in the gauze pads soaked with hypochlorite. In vitro studies showed that incubation of SM with 0.5% hypochlorite at a ratio of 10:1 (v/v) did not cause SM inactivation, whereas 4% hypochlorite reduced SM levels by 17%. However, at a decontaminant:SM ratio of 1000:1, 0.5% and 4% hypochlorite reduced SM levels by 92% and 99%, respectively. These findings are important for health authorities and regulatory agencies in planning precautionary steps to be taken in case of emergency and in routine laboratory work.

Bird's eye view observations of the subepidermal nerve network of normal guinea pig skin.

This study was undertaken to visualize the subepidermal nerve networks immunohistochemically. Specimens were obtained from the normal skin of the back, abdomen and nose of seven adult male Hartley guinea pigs, and immersed in 1 M NaCl solution. Dermal sheets were obtained by separating the dermis and epidermis, followed by fixation in Zamboni's fixative. The dermal sheets were sectioned parallel to the separated surface. Using the immunoperoxidase technique and immunofluorescence, the sections were immunostained with primary antibodies to S 100 protein (S100), protein gene product 9.5 (PGP 9.5), neuron-specific enolase (NSE), substance P (SP) and calcitonin gene-related peptide (CGRP). In double-labeled immunofluorescence of PGP 9.5 and SP or CGRP, the sections were viewed under a confocal laser scanning microscope. In skin of the back and abdomen, networks of S100-, PGP 9.5- and NSE-positive fibers were observed, some of which showed a multicentric arrangement. The outermost structures were formed by the thickest fibers which were 5-10 micro m thick, the outer networks consisted of fibers 3-6 micro m thick, and the inner networks consisted of fibers 1-3 micro m thick. From these networks, single fibers approximately 0.5 micro m thick branched out and terminated in free endings. The SP- and the CGRP-positive substances appeared as granules on the PGP 9.5-positive fibers. These results confirm that the dermis has a three-layered sensory nerve plexus, i.e. deep, superficial and subepidermal. In the skin of the nose, however, nerve networks were made up of only thick fibers which were probably situated in the subpapillary dermis.

Final report on the safety assessment of aluminum starch octenylsuccinate.

Aluminum Starch Octenylsuccinate is the aluminum salt of the reaction product of octenylsuccinic anhydride with starch. It is used in cosmetics at concentrations as high as 30% as an anticaking agent and a nonaqueous viscosity increasing agent. No information was available on the presence of impurities in the cosmetic-grade ingredient. When used in foods, Aluminum Starch Octenylsuccinate is identified as a modified food starch, and is subject to limitations on heavy metal residues. Oral studies using Aluminum Starch Octenylsuccinate or its related sodium salt produced no adverse systemic, reproductive, or developmental effects. Dermal injections produced no abnormal skin or systemic reactions in guinea pigs. Ocular toxicity was assessed in rabbits and using an in vitro test (chorioallantoic membrane vascular assay). In both cases no toxicity was seen. An acute inhalation toxicity study in rats was negative. Clinical tests indicated little irritation potential and no sensitization. Absent data on impurities in cosmetic-grade material, it was determined that such material should meet the same impurities requirements established for modified food starches. Based on these available data the Cosmetic Ingredient Review Expert Panel concluded that Aluminum Starch Octenylsuccinate is safe as used in cosmetic formulations provided that established limitations imposed on heavy metal concentrations are not exceeded.

Histamine is Involved in Ultraviolet B-Induced Pigmentation of Guinea Pig Skin

We previously reported that histamine induced melanogenesis in cultured human melanocytes and that the stimulatory effect was mediated by protein kinase A activation via H2 receptors. It is well-known that ultraviolet B irradiation causes acute inflammation, known as erythema, and subsequent pigmentation, and there are several reports demonstrating an elevation of the histamine levels in ultraviolet B-irradiated skin. Thus, to evaluate the involvement of histamine in ultraviolet B-induced skin pigmentation, we examined the effect of an H2 antagonist in brownish guinea pig skin. Daily exposure to 200 mJ per cm2 ultraviolet B for 3 d evoked erythema and subsequent pigmentation in the skin samples tested. Moreover, a remarkable increase in dopa-positive melanocytes was observed in the pigmented area, which showed an increase in melanin synthesis. Topical application of famotidine, an H2 antagonist, significantly reduced pigmentation and moderated the increase of dopa-positive melanocytes in the ultraviolet B-irradiated skin. Even when the initiation of famotidine application was delayed to day 2 after irradiation, an inhibitory activity on ultraviolet B-induced pigmentation was observed; however, the ultraviolet B-induced erythema was not suppressed by topically applied famotidine. Thus, we concluded that histamine is involved in ultraviolet B-induced pigmentation and that famotidine suppressed the pigmentation by the prevention of histamine binding to H2 receptors in melanocytes but not by prevention of ultraviolet B permeability and inflammation.

Joint Positive Control Testing in Guinea Pig Skin Sensitization Tests: A Harmonized Approach

A scheme for the performance of positive control studies within a coordinated group of laboratories was proposed (joint positive control testing). The procedure has been described, as well as the first results of the validation phase of this joint positive control testing project. Adoption of this proposal within the participating six laboratories would lead to a reduction in the number of guinea pigs required for reliability and sensitivity checks from current approximate 12 studies per year down to 2 studies, i.e., 150–300 fewer animals per year. Another benefit would be the use of a harmonized, and therefore more comparable, method to perform guinea pig tests and interpret the data. In the validation phase of joint reading of the positive control studies, the congruency of reading could clearly be demonstrated. From the experience gained up to now, it was possible to draw the conclusion that a coordinated interlaboratory approach for positive control testing was fully acceptable and an improvement with regard to animal welfare.

Formulation Optimization and Stability Study of Transdermal Therapeutic System of Nicorandil

The aim of this research investigation was to fabricate acrylate-based stable transdermal therapeutic system (TTS) of nicorandil, which could deliver drug through transdermal route. Monolithic TTS was fabricated in pressure sensitive adhesives (PSAs)—(a) terpolymer (PSA1) of 2-ethylhexyl acrylate, methyl methacrylate, and acrylic acid, (b) copolymer (PSA2) of 2-ethylhexyl acrylate, methyl methacrylate, acrylic acid, and vinyl acetate, and (c) Eudragit E100® pressure sensitive adhesive (PSA3). To enhance the flux of nicorandil, skin permeation enhancer N-methyl-2-pyrrolidone (NMP) was investigated at different concentrations (0.05–5%) in PSAs. Fabricated TTS was evaluated for in-vitro release and skin permeation through guinea pig skin. Maximum flux of nicorandil was observed from Eudragit E100 based TTS and kept for stability study at refrigeration, 25°C/30% RH and 30°C/60% RH. Patches were evaluated for various physicochemical parameters. Formulation was observed to be relatively more stable at refrigeration. Shelf life of the formulation was found to be 270, 270, and 30 days at refrigeration, 25°C/30% RH and 30°C/60% RH conditions, respectively. Nicorandil could be successfully derived from Eudragit E100 based TTS, but attention needs to be given to improve its chemical stability in formulation.

International Profiles in Toxicology: Biography of Vincenzo Cuomo, MD, Ph.D.

Aluminum Starch Octenylsuccinate is the aluminum salt of the reaction product of octenylsuccinic anhydride with starch. It is used in cosmetics at concentrations as high as 30% as an anticaking agent and a nonaqueous viscosity increasing agent. No information was available on the presence of impurities in the cosmetic-grade ingredient. When used in foods, Aluminum Starch Octenylsuccinate is identified as a modified food starch, and is subject to limitations on heavy metal residues. Oral studies using Aluminum Starch Octenylsuccinate or its related sodium salt produced no adverse systemic, reproductive, or developmental effects. Dermal injections produced no abnormal skin or systemic reactions in guinea pigs. Ocular toxicity was assessed in rabbits and using an in vitro test (chorioallantoic membrane vascular assay). In both cases no toxicity was seen. An acute inhalation toxicity study in rats was negative. Clinical tests indicated little irritation potential and no sensitization. Absent data on impurities in cosmetic-grade material, it was determined that such material should meet the same impurities requirements established for modified food starches. Based on these available data the Cosmetic Ingredient Review Expert Panel concluded that Aluminum Starch Octenylsuccinate is safe as used in cosmetic formulations provided that established limitations imposed on heavy metal concentrations are not exceeded.

Transdermal Delivery of Nicardipine: An Approach to In Vitro Permeation Enhancement

Nicardipine hydrochloride (NC-HCl), a calcium channel blocker for the treatment of chronic stable angina and hypertension, seems to be a potential therapeutic transdermal system candidate, mainly due to its low dose, short half-life, and high first-pass metabolism. The objective of the present study was to evaluate its flux and elucidate mechanistic effects of formulation components on transdermal permeation of the drug through the skin. Solubility of NC-HCl in different solvent systems was determined using a validated HPLC method. The solubility of drug in various solvent systems was found to be in decreasing order as propylene glycol (PG)/oleic acid (OA)/dimethyl isosorbide (DMI) (80:10:10 v/v) > PG > PG/OA (90:10 v/v) > polyethylene glycol 300 > ethanol/PG (70:30 w/w) > transcutol > dimethyl isosorbide (DMI) > ethanol > water and buffer 4.7 > 2-propanol. Propylene glycol was then selected as the main vehicle in the development of a transdermal product. As a preliminary step to develop a transdermal delivery system, vehicle effect on the percutaneous absorption of NC-HCl was determined using the excised skin of a hairless guinea pig. Vehicles investigated included pure solvents alone and their selected blends, chosen based on the solubility results. In vitro permeation data were collected at 37°C, using Franz diffusion cells. The skin permeation was then evaluated by measuring the steady state permeation rate (flux) of NC-HCl, lag time, and the permeability constant. The results showed that no individual solvent was capable of promoting NC-HCl penetration. Permeation profiles of the drug through hairless guinea pig skin using saturated solutions of drug were constructed. Among the systems studied, the ternary mixture of PG/OA/DMI and binary mixture of PG/OA showed excellent flux. The flux value of the ternary system was nearly three times higher than the corresponding values obtained for the binary solvent. A similar trend also was observed for the permeation conture stant, while the values of lag time were reversed. The ternary mixindicated was then selected as a potential absorption enhancement vehicle for the transdermal delivery of drug. In general, higher fluxes were observed through hairless guinea pig skin as compared with the human stratum corneum. Based on the results obtained from the release study of NC-HCl from saturated solutions of the drug, a novel lecithin organogel (microemulsion-based gel) composed of soybean lecithin, propylene glycol, oleic acid, dimethyl isosorbide, and isopropyl myristate was developed as a possible matrix for transdermal delivery of NC-HCl. In vitro percutaneous penetration studies from this newly developed gel system through giunea pig skin and human stratum corneum revealed that the organogel system has skin-enhancing potential and could be a promising matrix for the transdermal delivery of nicardipine. Furthermore, higher permeation rates were observed when nicardipine free base was incorporated into the gel matrix instead of hydrochloride salt.

Macroflux microprojection array patch technology: a new and efficient approach for intracutaneous immunization.

We evaluated the Macroflux microprojection array patch technology as a novel system for intracutaneous delivery of protein antigens. Macroflux microprojection array systems (330-microm micro-projection length, 190 microprojections/cm2, 1- and 2-cm2 area) were coated with a model protein antigen, ovalbumin (OVA), to produce a dry-film coating. After system application, microprojection penetration depth, OVA delivery, and comparative immune responses were evaluated in a hairless guinea pig model. Macroflux microprojections penetrated into hairless guinea pig skin at an average depth of 100 microm with no projections deeper than 300 microm. Doses of I to 80 microg of OVA were delivered via 1- or 2-cm2 systems by varying the coating solution concentration and wearing time. Delivery rates were as high as 20 microg in 5 s. In a prime and boost dose immune response study, OVA-coated Macroflux was most comparable to equivalent doses injected intradermally. Higher antibody titers were observed when OVA was administered with the microprojection array or intradermally at low doses (1 and 5 microg). Macroflux administration at 1- and 5-microg doses gave immune responses up to 50-fold greater than that observed after the same subcutaneous or intramuscular dose. Dry coating an adjuvant, glucosaminyl muramyl dipeptide, with OVA on the Macroflux resulted in augmented antibody responses. Macroflux skin patch technology provides rapid and reproducible intracutaneous administration of dry-coated antigen. The depth of skin penetration targets skin immune cells; the quantity of antigen delivered can be controlled by formulation, patch wearing time, and system size. This novel needle-free patch technology may ultimately have broad applications for a wide variety of therapeutic vaccines to improve efficacy and convenience of use.

POPULATION DIFFERENCES IN PREVALENCE TO Hev B 1 OR Hev B 6.02 ARE NOT DEPENDENT ON DERMAL PENETRATION

Health care workers (HCW) and spina bifida (SB) patients comprise two populations, which are particularly affected by latex allergy and demonstrate different profiles of sero-reactivity to individual latex proteins, with SB patients more frequently having antibodies to Hev b 1 and 3 and HCW to Hev b 5, 6, and 7. Given that HCW have extensive dermal exposure to latex proteins through the use of latex gloves, these studies were conducted to evaluate the percutaneous penetration of Hev b 1 and Hev b 6.02 as a potential factor in the divergent antibody responses observed in HCW and SB patients. Hairless guinea pig skin was used in in vitro flow through cells for percutaneous penetration studies and for immunohistological evaluation of protein localization in the skin. Skin samples were separated into intact and abraded exposure groups based on barrier integrity as measured by a 3H2O barrier test, and radioactive counts were determined for both skin and receptor fluid. Little protein penetration (less than 3%) was observed into or through intact skin samples following exposure to either protein. As expected, the degree of penetration through abraded samples was found to correlate significantly with the degree of abrasion for both proteins. Minimal disruption of the stratum corneum (less than 4% 3H2O penetration) was required to permit up to 50% Hev b 1 penetration. This was in contrast to the relationship observed for Hev b 6.02 where abrasion resulting in greater than 8% 3H2O penetration was required to permit more than 40% penetration of Hev b 6.02. Immunohistochemistry revealed Hev b 1 and Hev b 6.02 localized primarily in the stratum corneum when skin samples were intact and extending into the viable epidermis when abraded. These studies demonstrate that greater than 40% of Hev b 1 and Hev b 6.02 penetrate abraded skin with less abrasion required to achieve a higher degree of penetration with Hev b 1. Other factors including the amounts of individual proteins in latex products and physiological factors other than bioavailability through the skin must be considered in understanding the divergent antibody responses in HCW and SB patients.

TOXICITY OF ADIPIC ACID

ABSTRACTAdipic acid has very low acute toxicity in rats with an LD50> 5000 mg/kg. Adipic acid produced mild to no skin irritation on intact guinea pig skin as a 50% concentration in propylene glycol; it was not a skin sensitizer. Adipic acid caused mild conjunctival irritation in washed rabbit eyes; in unwashed rabbit eyes, there was mild conjunctival irritation, minimal iritis, but no corneal effects. Adipic acid dust may irritate the mucous membranes of the lungs and nose. In a 2-year feeding study, rats fed adipic acid at concentrations up to 5% in the diet exhibited only weight loss. Adipic acid is not genetically active in a wide variety of assay systems. Adipic acid caused no developmental toxicity in mice, rats, rabbits, or hamsters when administered orally. Adipic acid is partially metabolized in humans; the balance is eliminated unchanged in the urine. Adipic acid is slightly to moderately toxic to fish, daphnia, and algae in acute tests.

Prevention by polyhydroxysteroids and saponins of Asterina pectinifera of the desquamation of stratum corneum cells.

Two polyhydroxysteroids and three steroidal saponins (pectiniosides A, B and C) were isolated as bioactive substances from Asterina pectinifera. These compounds inhibited the release of guinea-pig skin stratum corneum cells by 48-67% (control, 0%) at 2 mg/ml. It is suggested that the bioactivity of these compounds is connected with the remedial and preventive effects of an aqueous extract of A. pectinifera on rough human skin.

Novel vitamin E derivative with 4-substituted resorcinol moiety has both antioxidant and tyrosinase inhibitory properties.

A novel vitamin E derivative, (6"-hydroxy-2",5",7",8"-tetramethylchroman-2"-yl)methyl 3-(2',4'-dihydroxyphenyl)propionate (TM4R), which has a chromanoxyl ring and 4-substituted resorcinol moieties, was synthesized; and its inhibitory effects on tyrosinase, antioxidant ability, and lightening effect of ultraviolet B (UVB)-induced hyperpigmentation were estimated. TM4R showed potent inhibitory activity on tyrosinase, which is the rate-limiting enzyme in melanogenesis. The scavenging activities of TM4R on 1,1-diphenyl-2-picrylhydrazyl and hydroxyl radicals were found to be nearly the same as those of alpha-tocopherol. Furthermore, an efficient lightening effect was observed following topical application of TM4R to UVB-stimulated hyperpigmented dorsal skin of brownish guinea pigs. These results suggest that TM4R may be a candidate for an efficient whitening agent, possibly by inhibiting tyrosinase activity and biological reactions caused by reactive oxygen species.