Preliminary observation on the lepidopteran colonization on rat and rabbit carcasses in Malaysia.

The immature stages of necrophagous insects such as Diptera and Coleoptera play a vital ecological role in carrion decomposition. These invertebrates reduce the necromass significantly through consumption and recycle nutrients into organic forms which are readily being used by autotrophs or served as an abiotic storage in the soil ecosystem. Fly and beetle larvae are frequently encountered decomposers on ephemeral resource patches; however, lepidopterans associated with carrion decomposition is seldom reported. Here, we report colonization of Monopis sp. (Tineidae) and an unknown species of Psychidae on a rat carcass, and a Lithosiini caterpillar (Arctiidae) on a rabbit carcass in Peninsular Malaysia for the first time. The feeding behaviour and their potential forensic implications are discussed.

Preliminary observation on the lepidopteran colonization on rat and rabbit carcasses in Malaysia

@#The immature stages of necrophagous insects such as Diptera and Coleoptera play a vital ecological role in carrion decomposition. These invertebrates reduce the necromass significantly through consumption and recycle nutrients into organic forms which are readily being used by autotrophs or served as an abiotic storage in the soil ecosystem. Fly and beetle larvae are frequently encountered decomposers on ephemeral resource patches; however, lepidopterans associated with carrion decomposition is seldom reported. Here, we report colonization of Monopis sp. (Tineidae) and an unknown species of Psychidae on a rat carcass, and a Lithosiini caterpillar (Arctiidae) on a rabbit carcass in Peninsular Malaysia for the first time. The feeding behaviour and their potential forensic implications are discussed.

The effects of sulfur mustard exposure and freezing on transdermal penetration of tritiated water through ex vivo pig skin.

The percutaneous absorption of tritiated water ((3)H(2)O) through sulfur mustard (SM) exposed abdominal pig skin was measured using in vitro Franz-type static diffusion cells. The barrier function to water permeation following exposure to liquid SM for 8 min and excision 3h later did not change significantly. A small, but statistically significant difference (P<0.05) in steady state penetration (Jss), permeability coefficient (Kp) and lag time (t(L)) of (3)H(2)O was observed between fresh skin and skin stored frozen (-20 °C) for up to two weeks. Steady-state penetration and Kp values were significantly higher (P < 0.05) in skin stored frozen compared with fresh skin. Fresh naïve skin had an average Kp of 1.65 × 10(-3) cm h(-1), whereas frozen naïve skin was 2.04 × 10(-3) cm h(-1). Fresh SM exposed skin had a mean Kp of 1.72 × 10(-3) cm h(-1), whereas frozen SM exposed skin was 2.31 × 10(-3) cm h(-1). Lag times were also shorter (P<0.05) in skin that had been stored frozen. Frozen, SM-exposed porcine abdominal skin may be used for in vitro penetration studies, but effects of treatment and storage on the barrier layer should be taken into account.

Reactive skin decontamination lotion (RSDL) for the decontamination of chemical warfare agent (CWA) dermal exposure.

Rapid decontamination of the skin is the single most important action to prevent dermal absorption of chemical contaminants in persons exposed to chemical warfare agents (CWA) and toxic industrial chemicals (TICs) as a result of accidental or intentional release. Chemicals on the skin may be removed by mechanical means through the use of dry sorbents or water. Recent interest in decontamination systems which both partition contaminants away from the skin and actively neutralize the chemical has led to the development of several reactive decontamination solutions. This article will review the recently FDA-approved Reactive Skin Decontamination Lotion (RSDL) and will summarize the toxicity and efficacy studies conducted to date. Evidence of RSDL's superior performance against vesicant and organophosphorus chemical warfare agents compared to water, bleach, and dry sorbents, suggests that RSDL may have a role in mass human exposure chemical decontamination in both the military and civilian arenas.

Detection and measurement of sulfur mustard offgassing from the weanling pig following exposure to saturated sulfur mustard vapor.

Animal models are employed to investigate mechanisms of injury and to evaluate protective measures against sulfur mustard (HD) exposure. The ability to detect and quantify HD enables the researcher to follow safe procedures in handling skin samples. We designed an experimental procedure to measure HD offgassing from animal models. A Minicams--a portable gas chromatograph equipped with a flame photometric detector and on-line sorbent collection and desorption--was used to monitor the HD concentration. Confirming measurements were made using a two-step process that trapped HD on a Tenax sorbent off-line and then transferred the sample by means of an ACEM 900 to a gas chromatograph equipped with either a flame photometric detector or a mass spectrometer. Sulfur mustard offgassing data are presented from three experiments in which weanling pigs were exposed to saturated HD vapor via vapor caps containing 10 microl of HD. The HD concentration was measured in time-weighted-average (TWA) units at a specific HD application site. The current 8-h maximum exposure limit for HD is 3-ng l(-1), (1 TWA unit). The largest TWA value measured near a 3 h time point was a Minicams measurement of 0.48 TWA at 2 h and 53 min after removal of a vapor cap containing HD from a single exposure site on an animal that had 24 concurrent dorsal exposure sites. Gas chromatography/flame photometric detection and gas chromatography/mass spectrometry were used to confirm the Minicams data and to provide greater sensitivity and selectivity down to 0.1 TWA. The gas chromatography/mass spectrometry data confirmed that HD concentrations fell below 0.1 TWA in <5 h for a specific site. These measurements of HD concentrations provided information on the expeditious and safe handling of HD-exposed tissue.

Development of a reactive topical skin protectant.

The use of a topical skin protectant (TSP) as a means of protecting troops from percutaneous chemical warfare agent (CWA) exposure has been proposed since these weapons were first used during World War I. The TSP is applied to vulnerable skin surfaces prior to entry into a chemical combat area. In 1990, the US Army Medical Research Institute of Chemical Defense transferred two non-reactive TSPs into advanced development. Following US Food and Drug Administration approval, the final product is expected to be available to soldiers in 1999. A continuing research effort is designed to develop a second-generation TSP that will increase effectiveness and also decontaminate CWAs into non-toxic products. We identified a list of 29 reactive moieties as potential additives to the TSP formulation. All candidate formulations are evaluated in a decision tree network, consisting of a series of 11 efficacy testing models. A prototype formulation (ICD 2701) containing the reactive ingredient S-330 has dramatically improved the protection against saturated sulfur mustard vapor. In addition, we have discovered a compound (ICD 2837) that significantly increases the skin's natural resistance to CWA penetration. Our goal is to transfer a significantly improved TSP formulation into advanced development by 1999.

Model for assessing efficacy of topical skin protectants against sulfur mustard vapor using hairless guinea pigs.

Sulfur mustard (HD; 2,2'-dichlorodiethyl sulfide) can produce incapacitating blisters in humans following dermal exposure. Most non-human animal models, however, do not form the large fluid-filled blisters observed in humans. Many models, nevertheless, do produce similar damage at the dermal/epidermal junction when evaluated by histopathology. In this study, it was observed that the hairless guinea pig (HGP) exhibits similar histopathological responses following exposure to HD vapor. Two sets of HGPs were exposed percutaneously for various lengths of time to HD vapor. In one set, the HGPs were sacrificed 24 h after exposure, and skin specimens were collected and processed for histopathology. In the other set, light reflectance was measured at skin test sites 4, 5, 6 and 24 h after exposure, to assess erythema. The Nikolsky's sign test was also performed 24 h after exposure by rotating a metal disk glued to the skin test site and inspecting the skin for loss of epidermis. Probit analysis of data indicated that the exposure durations that produced a 50% incidence of microblisters and Nikolsky's sign were ca. 7.5 and 4.5 min, respectively. Maximum erythema was observed 6 h following a 6 min exposure. Operating parameters for assessing the efficacies of skin protectants have been characterized.

Characterization of sulfur mustard vapor-induced cutaneous lesions on haired guinea pigs.

BACKGROUND/AIMS: Sulfur mustard (2,2'-dichlorodiethyl sulfide, HD) is a potent vesicating (blistering) agent. In this report, we describe the time-course and the dose-dependent response following cutaneous exposure to sulfur mustard (HD) in the haired guinea pig model. The purpose of this study was to evaluate the usefulness of the haired guinea pig as a vesicant research model. METHODS: Seventy-two animals were divided into nine groups of eight animals each. Hair on the dorsal side of each animal was removed by clipping with an electric clipper followed by application of a chemical depilating agent (MAGIC Shaving Powder). Six dorsal skin sites on each animal of a given group were exposed to saturated HD vapor (1.4 mg/l) for one of nine exposure times between 0-8 min. Lesions were evaluated for erythema (reflectance colorimeter) and edema (ultrasound imaging) at 4, 6, 12, and 24 h postexposure. Damage at the dermal-epidermal junction (DEJ) was evaluated by histopathology at 24 h postexposure. RESULTS: We observed that the hair removal process was time-consuming, produced significant initial erythema, and resulted in increased dorsal skin sensitivity to low HD exposure levels. The time-course of exposure response to HD was observed to be dose-dependent and similar to the hairless guinea pig model. CONCLUSIONS: The haired guinea pig is inferior to the hairless guinea pig as a vesicant model due to the complications resulting from the hair removal process. However, the haired guinea pig is a useful model for evaluating the cutaneous effects of HD vapor and can be developed into a routine screening tool for the evaluation of topical barriers against HD vapor exposure.

Nikolsky's sign: a novel way to evaluate damage at the dermal-epidermal junction.

BACKGROUND/AIMS: Sulfur mustard (2,2'-dichlorodiethyl sulfide, HD) is a potent vesicating (blistering) agent. Cutaneous exposure causes the destruction of basal cells and leads to a separation at the dermal-epidermal junction. To evaluate the efficacy of candidate antivesicant compounds, suitable animal models are needed. A tape stripping method and the Dermal Torque Meter (DTM) have been used in novel applications to evaluate for the Nikolsky's sign in the hairless guinea pig. The Nikolsky's sign is the separation and loss of the epidermis from the dermis when the skin is pressed with a sliding or twisting motion. The purpose of this study was to find an objective, reproducible, and quantitative method that could be used as an end-point to evaluate the degree of damage at the dermal-epidermal junction following cutaneous HD vapor exposure. METHODS: Hairless guinea pigs were exposed to saturated HD vapor (1.4 mg/l) for time intervals between 2 and 9 min using 14-mm vapor cups. At 24 h post-exposure, both tape stripping (fabric carpet tape) and a DTM were used to produce the Nikolsky's sign in animals under anesthesia. Using the tape stripping method, 15-mm disks of tape were applied to each skin site. After 5 s the tape was peeled off. The D T M was used to apply a horizontal twisting motion to the skin. The parameters included a 15-mm center disk, a ring gap of 1 mm, a torque of 30 mNm, and a 5-s cycle time. A cyanoacrylate adhesive was used to secure the center disk and guard ring to the skin. The loss of the epidermis was determined by visual observation and confirmed by histopathological examination. The standard D T M unit was modified to use multiple center disk/guard ring assemblies so that several sites on each animal could be evaluated at the same time. RESULTS: The mean (±S E M) percent incidence of positive Nikolsky's sign observations using the tape stripping method for HD vapor exposures of 3,5,7, and 9 min was 0,50 (±16), 94 (±6.2), and 100, respectively. The mean (±S E M) percent incidence of positive Nikolsky's sign observations using the D T M method for HD vapor exposures of 2, 3, 4, and 5 min was 0, 25 (±7.1), 91 (±2.9), and 96 (±2.3), respectively. CONCLUSIONS: The Nikolsky's sign produced by the tape stripping method and the D T M were useful in evaluating damage at the dermal-epidermal junction following cutaneous HD vapor exposures. These methods have the potential to replace histopathology as an end-point for routine screening procedures designed to evaluate the efficacy of antivesicant compounds.

Surface roughness of finished composite resins.

This study evaluated the results of polishing composite resin by using the following finishing and polishing techniques: Arkansas stone burs; eight-blade tungsten-carbide burs; diamond burs; aluminum-oxide disks; no polishing; and 12- and 30-blade tungsten-carbide burs. The results were compared to ascertain which technique delivers the smoothest surface. The study was done with 120 class V restorations on extracted human teeth distributed in two groups (I and II) of 60 restorations each. Group I teeth samples were filled with microfilled composite resin and Group II with a hybrid composite resin. Readings were made with a profilometer to evaluate the final polishing. The conclusions from the results of the study were that microfilled composite resins provided a better finish when treated with aluminum-oxide disks. These results were statistically significant (p < 0.001). When hybrid composites were used the control group recorded the lowest values.

Antimicrobial activity of seven root canal sealers. Results of agar diffusion and agar dilution tests.

A comparative study of the antimicrobial action of seven root canal sealers: Traitement Spad, Endométhasone, N2 Universal, Diaket-A, AH26 with silver, Tubli Seal, and Sealapex was done with 120 strains of Staphylococcus aureus. Two antimicrobial susceptibility tests were used: the agar dilution test and the agar diffusion test. The Diaket-A and Traitement Spad sealer cements showed the highest efficiency in the dilution test, whereas Diaket-A was in fourth place in the diffusion test, only better than the antimicrobial activity of the Tubli Seal and Sealapex sealers.

[Behavior of different strains of Staphylococcus aureus against root canal filling cements]. / Estudio del comportamiento de diferentes cepas de Staphylococcus aureus frente a los cementos de obturación de conductos radiculares.

The mean goal of this study is the determination of the conduct of 120 strains of Staphylococcus aureus against seven root canal sealers: Traitement Spad, Endométhasone, N2 Universal, AH26 with silver, Diaket-A, Tubli Seal and Sealapex. The agar diffusion test was employed in the determination of its bacterial growth inhibition. The results obtained have demonstrated values very different between the tested strains. Therefore we recommended to employ strains with reference in the investigation of the bacterial growth inhibition in order to repeat equal experimentation conditions.

Hairless guinea pig bioassay model for vesicant vapor exposures.

Sulfur mustard (HD; 1,1'-thiobis[2-chloroethane]) induces fluid-filled blisters in man but not in conventional laboratory animals. An animal model is needed to emulate both cytotoxic (vesicant) and vascular (irritant) responses of human skin to HD exposures. An acceptable model must permit reproducible comparisons of uniformly graded and dose-related HD control responses with reduced responses that may follow antivesicant treatments. Hairless guinea pigs were evaluated by exposing six or eight dorsal skin sites 12 mm in diameter to similar HD vapor concentrations for graded intervals (1-16 min). HD vapor was delivered under occlusive caps holding 10 microliters of HD in filter paper located 5 mm above the skin. Four-minute exposures induced moderate erythema, slight edema, and microblisters in 1 of 39 sites. Eight-minute exposures induced severe erythema, moderate edema, and microblisters in 31 of 40 sites. Gross blistering was not seen after use of vapor cups, but damage to basal cells resembled lesions of vesicant injury in man. The hairless guinea pig model, with graded HD vapor exposures, provides acceptable comparisons of responses. Exposures of both 4- and 8-min durations were used to show the feasibility of using this model to bioassay antivesicant topical protectants. These methods may be useful for measurements of irritant and cytotoxic responses of skin to other toxic vapors.