Therapeutic effect of dexamethasone in T-2 toxicosis

Other biologic toxin bioweapons: ricin, staphylococcal enterotoxin B, and trichothecene mycotoxins

The ideal biologic warfare agent is lethal, easy, and inexpensive to produce in large quantities, stable in aerosol for/with the ability to be dispersed over wide areas, has no effective treatment or vaccine, and is communicable from person to person. With the exception of the last characteristic, the biologic toxins (ricin, staphylococcal enterotoxin B, T-2 mycotoxin, and botulinum) possess all the properties mentioned. This article will discuss the first three biologic toxins, with an emphasis on particular points of interest to the dermatologist. Botulinum toxin will be covered in another article.

When biotoxins are tools of terror. Early recognition of intentional poisoning can attenuate effects

Toxin-mediated diseases have made humans ill for millennia. They also have been used in beneficial ways. Unfortunately, the use of biological agents as weapons of terror has now been realized, and separating naturally occurring disease from bioterroristic events has become an important public health goal. The key to timely identification of such attacks relies on education of primary care physicians, first responders, and public health officials. We must remain vigilant to unusual case presentations or clusters of similar cases and report them immediately to public health authorities.

Influence of glucocorticoids and activated charcoal on the lethality of rats after acute poisoning with T-2 toxin, diacetoxyscirpenol, or roridin A

Lethal doses of the trichothecene mycotoxins T-2 toxin (1.5 mg/kg), diacetoxyscirpenol (DAS; 2.3 mg/kg) or roridin A (1.3 mg/kg) were intravenously administered to rats. When rats were treated with either activated charcoal (Superchar liquid, Norit A; 1 g/kg, po) or dexamethasone (8 mg/kg, iv) 30 min after poisoning with one of the trichothecenes, lethality was only marginally reduced. However, when the combination of activated charcoal (Superchar liquid or Norit A) and dexamethasone was administered, the survival rate of animals after 30 days was significantly enhanced by up to 50%. Comparison between 2 preparations of activated charcoal, Norit AR with a surface area of 1,000 m2/g and Superchar liquidR with a surface area of 3,000 m2/g, each in combination with dexamethasone, revealed no difference in their therapeutic efficacy. Prednisolone (60 mg/kg) was as effective as dexamethasone (8 mg/kg), each administered with activated charcoal, in preventing death in acute T-2 toxicosis.

Comparative tissue distribution and excretion of orally administered [3H]diacetoxyscirpenol (anguidine) in rats and mice

A quantitative comparison of tissue distribution and excretion of an orally administered sublethal dose of [3H]diacetoxyscirpenol (anguidine) was made in rats and mice 90 min, 24 hr, and 7 days after treatment. Total recoveries of 95-100% were obtained. Approximately 90% of the dose was excreted in urine and feces during the first 24 hr with a feces:urine ratio of about 1:4.5 in both species. Carcass and tissue radioactivity dropped rapidly during the first 24 hr but remained relatively constant at low, but detectable, levels (1.5-3.5% of dose) over the course of the experiment. Few substantive interspecies differences were noted in tissue distribution. At 90 min the highest percentage of dose was in tissues involved in sequestering diacetoxyscirpenol because of high body water/lipid content (carcass, skin) or the absorption (stomach, small intestine), metabolism (liver), or excretion (kidney) of the toxin. The rank order of these tissues was generally stable over the course of the experiment. When data were expressed as specific radioactivity (dpm/g tissue) instead, the carcass and skin dropped from the top rank tissues at 90 min and were replaced by the spleen and cecum. At 24 hr and 7 days the top-ranked order of tissues shifted to include organs associated with trichothecene-induced toxicity such as the lymphohematopoietic system (spleen, thymus, and femur bone marrow), heart, and testis (in mouse) as well as the cecum and large intestine. In addition, the rate of loss of radioactivity with time generally did not decrease as rapidly in these target organs as observed in liver, kidney, skin, and carcass. Brain radioactivity, though very low, also diminished relatively slowly. Significant differences in specific radioactivity which did occur between the rat and mouse tended to occur in target organs and with the higher levels present in the mouse. These data were discussed in terms of interspecies differences in lethality and target organ toxicity.

Opposite effect of adrenalectomy on rat brain prostaglandin synthesis in basal conditions and in response to insulin or 2-deoxy-glucose

In the present study we evaluated the role of endogenous glucocorticoids in the biosynthesis of prostaglandins (PG) in cortical brain tissue of the rat. Experiments were carried out under basal conditions and in response to insulin-induced hypoglycemia and 2-deoxyglucose (2-DG) induced-cytoglucopenia. In intact rats, following hypoglycemia and cytoglucopenia, the production of brain PG was decreased. These two stress stimuli also activated adrenocortical secretory responses, as manifested by an increase in circulating ACTH and corticosterone. Bilateral adrenalectomy did not modify the brain production of PG under basal conditions. In contrast, in adrenal-ectomized rats, the biosynthesis of brain cortical PG was markedly increased in response to insulin and 2-DG. These results suggest that adrenal hormones may be involved in the modulation of cortical PG production under stressful conditions.