A serious skin sulfur mustard burn from an artillery shell.

Despite the Geneva Protocol of 1925 and the Paris Conference on Prohibition of Chemical Weapons in 1989, sulfur mustard and other chemical weapons continue to pose a hazard to both civilians and soldiers. The presence of artillery shells containing sulfur mustard, both in waters where these shells were dumped and in old battlefields, presents a problem in times of peace, especially for those who collect wartime memorabilia. Past literature has reported several hundred incidents involving fishermen who inadvertently pulled leaking shells aboard their fishing vessels, thereby exposing themselves to the vesicant chemical. Other literature reports exposure to children who found the chemical shells in old battlefields. The purpose of this article is to report the first case of a serious sulfur mustard burn that occurred after removing the detonator from an old artillery shell in a historic battle field near Verdun, France. The circumstances surrounding the injury, the diagnosis and management of injuries secondary to sulfur mustard, and the long-term consequences to the patient are presented and discussed. Although skin grafting has been used in the management of other chemical burn injuries, this report is the first to describe the need for split-thickness skin grafts in the management of a patient with sulfur mustard burns.

2,2'-Dichlorodiethyl sulfide (sulfur mustard) decreases NAD+ levels in human leukocytes.

2,2'-Dichlorodiethyl sulfide (sulfur mustard, HD) extensively alkylates DNA in a concentration-dependent manner in many cell types. We have proposed a biochemical hypothesis that explains HD-induced injury by linking DNA alkylation and DNA breaks with activation of poly(ADP-ribose) polymerase, resulting in depletion of cellular NAD+. This hypothesis was tested by treating human leukocytes with HD to determine whether NAD+ depletion occurred as predicted. These cells demonstrated a decrease in NAD+ levels which was dependent on both concentration of HD and time after exposure. Inhibitors of poly(ADP-ribose) polymerase or substrates for NAD+ synthesis were able to prevent the HD-induced NAD+ decrease.

Regulation by serine esterase of histamine release from human leukocytes--I. Direct release of histamine by the serine esterase inhibitors diisopropyl fluorophosphate (DFP) and soman (GD).

The serine esterase inhibitor diisopropyl fluorophosphate (DFP) had been reported previously to inhibit IgE-dependent histamine release. Recently, it has been demonstrated that lower concentrations of DFP enhance IgE-dependent histamine release and inhibit desensitization. This manuscript describes the abilities of several esterase inhibitors to cause release of histamine from human leukocytes (basophils), by a process that is IgE-independent. This esterase inhibitor-induced histamine release appears to be by a non-cytotoxic mechanism that requires calcium and is temperature dependent. These histamine release processes occurred over a longer period of time than IgE-dependent release. Direct release of histamine by these small molecular weight inhibitors and inhibition of desensitization both suggest that one or more serine esterases are involved in the regulation of histamine release from human basophils.

Molecular basis for mustard-induced vesication.

A biochemical hypothesis explaining the generation of pathology in human skin by mustard gas (HD) is presented which links the initiation of DNA damages to local alterations of metabolism and subsequent development of blisters. The proposed sequence involves HD alkylation of purines in DNA which are processed to form apurinic sites. Apurinic endonucleases act at these sites to produce backbone breaks in DNA which cause activation of the chromosomal enzyme poly(ADP-ribose)polymerase. This enzyme utilizes NAD+ as a substrate and, at vesicating doses of HD, would deplete the cells of their NAD+ content. The depletion in NAD+ would cause inhibition of glycolysis, and the resulting accumulation of common intermediates would stimulate the NADP+-dependent hexosemonophosphate shunt (HMS). Such stimulation of the HMS has been associated with DNA damage and enhancement of protease synthesis and release. These proteases could be responsible for development of subepidermal blisters which result from fluid accumulation in the cavity created by separation of the moribund basal cell layer from the basement membrane--a characteristic feature of HD-exposed human skin. Partial validation of this biochemical hypothesis has been achieved. DNA alkylated with either monofunctional or bifunctional sulfur mustards, followed by spontaneous or enzymatic depurination, was shown to be sensitized to degradation by apurinic endonuclease. Studies on the effect of HD on human skin grafted to athymic nude mice demonstrated dose- and time-related decreases in NAD+ levels. These decreases in NAD+ levels preceded and correlated to the predicted severity of pathology. The participation of poly(ADP-ribose)polymerase activity in the HD-induced NAD+ loss was substantiated by prevention of this loss in the presence of inhibitors of the enzyme. Additional supporting evidence for the proposed mechanism was obtained at the cellular level by studies which utilized human leukocytes. The subsequent involvement of the HMS and proteases in HD-induced vesication is discussed.

Sulfur mustard lowers nicotinamide adenine dinucleotide concentrations in human skin grafted to athymic nude mice.

Human skin grafted to athymic nude mice shows a decrease in nicotinamide adenine dinucleotide (NAD+) concentrations when exposed to sulfur mustard (HD). The lowering of NAD+ is dependent on both dose of HD and time after exposure. When HD is applied to grafted skin at 127 micrograms/cm2, the decrease in NAD+ begins immediately after exposure, approaches minimal values by 4 hr. NAD+ returned to normal within 18 hr. With higher concentrations of HD, NAD+ concentrations fall precipitously within 4 hr, reach a minimum value at 18 hr, and seem to remain at this depressed value for at least 72 hr. NAD+ loss appears to precede and be proportional to tissue injury. Pretreatment of mice with 3-aminobenzamide, a specific inhibitor of poly(ADP-ribose) polymerase, seems to lessen the effect of HD. At higher concentrations of HD, human grafts from mice pretreated with 3-aminobenzamide show significant protection from loss of NAD+ levels after 4 hr.

Histamine release by esterase inhibitors. The regulation of histamine release from human leukocytes of allergic and non-allergic individuals by the serine esterase inhibitors diisopropyl fluorophosphate and pinacolyl methylphosphorofluoridate.

The serine esterase inhibitor diisopropyl fluorophosphate (DFP) has been shown to inhibit IgE-dependent histamine release. Recently, it has been demonstrated that lower concentrations of DFP enhanced IgE-dependent histamine release and inhibited desensitization. This manuscript describes the ability of another esterase inhibitor, pinacolyl methylphosphorofluoridate (soman), to directly cause release of histamine from human leukocytes (basophils) by a process that is IgE-independent. This release process requires calcium and is also temperature-dependent but occurs over a longer period of time than IgE-dependent release. These data suggest that there is a serine esterase which controls histamine release, and inhibition of this esterase causes histamine release.

Formation of O6-ethylthioethyldeoxyguanosine from the reaction of chloroethyl ethyl sulfide with deoxyguanosine.

O6-Ethylthioethyldeoxyguanosine has been synthesized from 6-chloro-3',5'-di-O-acetyldeoxyguanosine and characterized by UV, fluorescence, and mass spectrometry. High-pressure liquid chromatography studies have shown that this modified nucleoside is formed when the one-armed sulfur mustard, chloroethyl ethyl sulfide, reacts with deoxyguanosine. This result supports the hypothesis that the mutagenic effects of the sulfur mustards are caused in part by substitution of the O6-position of deoxyguanosine.

Pathogenesis of skin lesions caused by sulfur mustard.

Sulfur mustard (SM) (di-2-chlorethyl sulfide), used for chemical warfare in World War I, is a highly reactive radiomimetic alkylating agent. When applied to the skin of rabbits and guinea pigs, it produced vascular leakage, leukocyte infiltration, and slow death of basal epidermal cells. Thirty to sixty minutes after exposure to SM, injury to the superficial microvasculature (beneath the SM application site) was detected by measuring vascular leakage with Evans blue dye and also with horseradish peroxidase. At this same time, injury to the superficial fibroblasts was observed ultrastructurally; and an unexpectedly high percentage of basophils was found among the early infiltrating granulocytes. At 2 to 4 hr, the vascular leakage ceased, and had resumed by 8 hr in a more diffuse form. At this time, the basal epidermal cells showed pyknotic nuclei, an increase in their lysosomal enzymes (observed histochemically), and autophagic vacuoles (observed ultrastructurally). Leukocyte infiltration was marked, consisting mostly of heterophils (PMN) with a reduced percentage of basophils. During the next 24 to 72 hr, the entire inflammatory reaction reached its peak; and a superficial, crust-covered ulcer developed. Then, over the next 10 days, the lesion gradually subsided with concomitant repair and healing. Glucocorticosteroids decreased the early edematous phase, but did not affect the rate of healing. These findings suggest that the skin response to sulfur mustard has an immediate and a delayed phase. The immediate phase, i.e., within the first hour, was characterized by injury to the superficial fibroblasts and to the endothelium of superficial capillaries and venules, possibly because of direct damage to their cell membranes. At this time, a restricted vascular leakage and a selective granulocyte infiltration containing many basophils occurred. The delayed phase, which became evident after 8 hr, was characterized by the death of basal epidermal cells, probably because of DNA damage. This phase was accompanied by generalized vascular leakage, by massive heterophil immigration, and eventually by ulceration.

Spontaneous reactivation of acetylcholinesterase following organophosphate inhibition. II. Characterization of the reactivating components.

Repeated cycles of inhibition by a variety of organophosphates followed by spontaneous reactivation reveal a component of electric eel acetylcholinesterase (acetylcholine hydrolase, EC 3.1.1.7) which preferentially reactivates. That the observed enzymatic activity truly resides in acetylcholinesterase is indicated by its sensitivity to a specific inhibitor and by molecular weights for subunits and native enzyme which are approximately the same as those for the major fraction of enzymatic activity which behaves in the classical manner. The Km values for phenyl acetate of the two components are similar but the rate constant for covalent bond formation, k2, with isopropyl m-nitrophenyl methylphosphonate is greatly reduced in the spontaneously reactivating species. The molecular basis for these observations is discussed.

Involvement of separate pathways in the repair of mutational and lethal lesions induced by a monofunctional sulfur mustard.

The mutagenic and lethal effects of a monofunctional sulfur mustard, 2-chloro-ethylethylsulfide (CEES), have been studied in a number of repair deficient variants of Escherichia coli K12, B/r and B. The results indicate that CEES induces a (pre)mutational lesion which is subject to Uvr+-excision-repair. Extensive CEES-induced mutagenesis can occur in exrA- uvrA- and recA- uvrB- variants suggesting that the majority of the mutations in Uvr-bacteria do not arise from error-prone repair. These findings are similar to results previously reported with a volatile degradation product of captan and with ethyl methanesulfonate (EMS) but differ from those reported with methyl methanesulfonate (MMS). It is hypothesized that CEES alkylates guanine at the O-6 position (R-O-6-G) and that this R-O-6-G which is Uvr+-excisable is directly mutagenic by producing G-C to A-T transitions during replication. Reduced levels of induced mutation frequencies observed in an endonuclease II-deficient variant lead us to postulate that, in constrast to Uvr- bacteria, CEES-induced mutation in wild-type cells arise from error-prone repair of apurinic sites. Analysis of the lethal actions of CEES indicates that the lesion produced is largely unexcisable by the Uvr+ system. Host-cell reactivation of CEES-treated TI bacteriophage shows that the production of the (pre)ethal lesion is dependent on both the initial dose and post-treatment incubation. The efficient repair of the (pre)ethal lesion requires both endonuclease II and polymerase I. Moreover, deficiencies of these two enzymes rendered bacteria more sensitive to the cytotoxic action of CEES. It is postulated that the lethal mechanism of CEES involves: (I) alkylation at the N-3 position of adenine and the N-7 position of guanine; (2) spontaneous depurination of these alkylated bases; and (3) production of apurinic sites which are lethal unless repaired by the endonuclease II-polymerase I excision-repair system.

Increased rate of acetylcholinesterase synthesis in differentiating neuroblastoma cells.

When neuroblastoma cells (N18) in vitro are maintained in the absence of serum, the specific activity of AChE begins to rise rapidly after an initial lag period of about 2-3 days, reaching a maximum level (10-20-fold increase) by 7 days after induction. In order to clarify the mechanism of induction, it was necessary to measure the rate of AChE synthesis and its sensitivity to metabolic inhibitors. Return of enzymatic activity after irreversible inhibition of AChE in "differentiated" cells was blocked by cycloheximide, but not by cordycepin or actinomycin D, suggesting that protein but not mRNA synthesis was required for replacement. By using the initial rate of this replacement as a measure of the rate of synthesis of the enzyme, it was shown that cells which had differentiated in the absence of serum synthesized AChE 50-fold faster on a specific activity basis than their undifferentiated counterparts. In contrast, cordycepin effectively blocked the increase in the rate of AChE synthesis that occurs as a result of serum deprivation, indicating that the induction process itself requires the synthesis of new mRNA. Axonation, another index of differentiation, was not completely blocked by inhibition of RNA or protein synthesis and presumably utilizes only pools of pre-existing structural proteins.