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The concept of the sea as a source of noxious agents is perhaps not a familiar one to clinical neurologists, judging by the lack of reference to these agents in standard textbooks. Chemical, physiologic, and pharmacologic laboratories are increasingly investigating the properties of marine toxins, finding in them compounds with interesting and novel structures or unusual physiologic effects. Such substances are seen as possible agents for biologic and, more particularly, physiologic research, and as possible sources of new pharmaceuticals. These include hormone-like substances and antiviral or antitumor agents. Despite these specialized developments, which are in large measure a consequence of the technological advances of the present century, the clinician is at times directly concerned with the effects of marine toxic substances. For example, in Japan, puffer fish or tetrodotoxic poisoning is one of the major causes of deaths from food poisoning. Another marine toxin that has caused many explosive outbreaks of food poisoning. with many deaths in various parts of the world, comes from clams or mussels. This toxin, saxitoxin, is produced by species of marine protozoa including Gonyaulax, and is concentrated in filter-feeding molluscs. These two examples were of significant interest in medicine long before the technologic developments of the twentieth century. In the last few decades, entirely new problems of marine intoxication have arisen as a result of marine pollution from the disposal of industrial wastes in the sea. The most striking example of a man-made marine intoxication has been the outbreak of Minamata disease. In Minamata, Japan, the disposal of mercury-contaminated industrial wastes from a plastics factory into an enclosed bay, followed by human consumption of the contaminated fishes, crabs, or shellfish, led to many instances of acute cerebral degeneration. With the increasing exploration of the sea for both pleasure and economic exploitation, which is a feature of the second half of the twentieth century, it may be expected that the frequency and variety of human intoxications by marine creatures will be increased. This chapter reviews the neurologic effects of noxious substances of marine biologic origin. The subject is now developing so rapidly that overall surveys, such as this, of the general animal life of theocens will soon be beyond the scope of a single review. Nevertheless, it is hoped that the references given will enable the interested reader to pursue particular aspects further.

Polyclonal antibodies raised against a synthetic peptide (sequence 50-59) of Androctonus australis Hector toxin II can neutralize the effects of toxin II in vivo. The antigenic specificities of anti-peptide and anti-toxin antibodies were compared by competitive aqueous phase radioimmunoassay by using 125I-toxin II, chemically modified or homologous toxins, and the synthetic peptide 50-59, either free or bound to bovine serum albumin (BSA). The antipeptide and anti-toxin antibodies had a comparable high affinity for the native toxin, but anti-peptide antibodies exhibited a lower binding capacity. Anti-peptide antibodies had a higher affinity for native toxin than for the peptide 50-59 bound to BSA, used as immunogen, and were unable to recognize the free peptide. These results suggest that it is necessary to restrict the conformational freedom of the immunizing peptide in order to obtain anti-peptide antibodies with a high affinity for the toxin. The lysine residue at position 58 of toxin II, essential for toxicity, appears to be immunogenic when immunization is with peptide 50-59 bound to BSA and not with the native toxin. This residue is antigenic in the native toxin, however, as shown by the anti-peptide antibodies.

Toxins produced by Clostridium difficile have been implicated in the etiology of antibiotic-induced colitis. Clostridium difficile antitoxin is not available, but recent studies have shown that toxins present in the feces of patients with this disease are neutralized by Clostridium sordellii antitoxin. We found that C. sordellii antitoxin neutralized toxins produced in broth cultures of either C. sordellii or C. difficile and that passive immunization with C. sordellii antitoxin before challenge with clindamycin prevented colitis in hamsters. Significantly fewer antitoxin-treated animals than unimmunized controls developed diarrhea and died with hemorrhagic colitis. Administration of 300 U of antitoxin parenterally either on the day of challenge with clindamycin or 24 hr later provided significant protection (25% mortality vs. 100% mortality in controls, P less than 0.01). None of eight animals given antitoxin (300 U) both on the day of challenge and 24 hr later died. Filtrates prepared from cecal contents of dead or killed hamsters were tested for toxicity by intraperitoneal injection into hamsters and by addition to monolayers of monkey kidney cells. Fecal filtrates from antitoxin-protected animals were not toxic in these assays, but filtrates from control animals were uniformly toxic. Passive immunization against clostridial toxins was protective against clindamycin-associated colitis in this model. This finding further substantiates the importance of these toxins in the pathogenesis of antibiotic-induced colitis.

The salient steps of a 20-year programme of research into the nature of burn disease are described. By burn disease we mean the late mortality and morbidity following burns. We have isolated a burn toxin which is derived from a thermal polymerization of cell membrane lipoproteins within the dermis and have studied its influence on the effects of sepsis. We have also used it in the development of active and passive immunization therapy of severe burns.

The pathophysiology of antibiotic-associated colitis was studied in rabbits with severe ileocolitis induced by oral administration of clindamycin. Cell-free, sterile filtrates of cecal contents of rabbits with clindamycin colitis contained a toxin that was lethal for mice and cytotoxic for HeLa-cell monolayers. The toxin was heat labile, was inactivated by pronase but not trypsin, and had a mol wt by gel filtration on Sephadex G-100 of 45,000. The toxin was neutralized by antiserum to Clostridium perfringens type E, but not by other clostridial antisera. The toxin also caused severe necrosis of rabbit rectal epithelium during 18-hr organ culture, which could be completely reversed by neutralization with C. perfringens type E antiserum. These studies indicate that clindamycin colitis in rabbits is caused by overgrowth of a clostridial species, which releases a heat-labile toxic protein of mol wt of 45,000 capable of necrosing colonic epithelial cells.

The hamster model of clindamycin-induced enterocolitis was studied to determine the natural course of the disease and the response to five therapeutic regimens. Tissue culture assays of stools from untreated animals showed that colitis toxin is present at low titers within 24--36 hr after challenge with clindamycin; titers of toxin in subsequent specimens of stool increased progressively until the animals died on days 2--4 after challenge. Therapeutic regimens tested in this model were initiated 24 hr after clindamycin challenge when the majority of the animals had evidence of colitis toxin. Methylprednisilone, an anion exchange resin, and gas gangrene polyvalent antitoxin had a minimal effect on toxin titers in stool and failed to delay substantially death due to enterocolitis. Vancomycin and tetracycline eliminated toxin in stools and delayed death. However, the salutary effects of these antibiotics were noted only during the course of their administration since all animals died of enterocolitis and had high titers of toxin when treatment was discontinued.

A conjugate of the monoclonal antibody WT1 and ricin A-chain was studied for its suitability for purging marrow of leukemic T cells for autologous transplantation in T cell acute lymphocytic leukemia (T-ALL). The conjugate was powerfully cytotoxic to the human T-ALL cell line, GH1, which expresses the WT1 antigen at a high density. Treatment of the cells with the conjugate at 10(-11) M reduced their rate of protein synthesis by 50%, and the inclusion of 6 mM ammonium chloride in the cultures enhanced the potency of cytotoxic effect by 10-100-fold. Clonogenic assays indicated that less than 0.1% of GH1 cells survived 3-hr exposure to the conjugate in ammonium chloride. WT1 alone did not react with multipotent (CFU-GEMM) hematopoietic progenitors in normal human bone marrow, as measured by fluorescence-activated cell sorting. Under conditions giving maximal killing of GH1 cells, there was no toxicity to multipotential progenitors in normal human marrow.

A collected series from the English literature up to 1984 of spontaneous clostridial myonecrosis (SCM) is presented in order to reveal possible common denominators. SCM was associated with malignancy (colonic cancer and leukaemia), diabetes, and injections in descending order. C. perfringens was isolated in more than 70% of the cases followed by C. septicum in 27 and C. novyi in 7%. The pathogenesis is still speculative but is thought to be due to bacteraemia especially from the gastrointestinal tract, due to growth of dormant spores in tissue following antecedent trauma or as an infection descending along the ilio-psoas sheath from a gastrointestinal focus. The symptoms are pain in an oedematous, discoloured, crepitant area with haemorhagic bullae and often shock. The diagnosis is based on the clinical findings and Gram-positive rods in the exudate. Treatment instituted promptly constitutes of surgical debridement, antibiotics and hyperbaric oxygen. The prognosis of SCM is worse than for other cases of clostridial myonecrosis and survival was in this collected series only 19%.

Outbred Swiss mice were inoculated intraperitoneally or intravenously with one 90 to 100% lethal dose of Escherichia coli O:18, Proteus mirabilis, or Klebsiella pneumoniae. After carefully timed intervals, aminoglycoside antibiotics were begun at dosages nnd intervals predetermined to constitute optimal therapy. With progressive increases in delay of antibiotic therapy, mortality rates increased progressively from 0% to 90 to 100%. Standardized models of infection were developed by selecting delay periods before initiating antibiotic therapy such that 50 to 70% mortalities resulted. Utilizing these models, agents with reputed anti-endotoxin activity were administered concomitantly with the delayed antibiotic therapy to determine if any could prevent gram-negative septic mortality no longer preventable by the antibiotics alone. The following were observed: (i) adrenal corticosteroids prevented mortality that was no longer preventable by optimal aminoglycoside antibiotics alone. The following were preventable by optimal aminoglycoside antibiotic therapy alone; (ii) specific antisera also did so, provided anaphylaxis was circumvented; (iii) in one model (P. mirabilis), such protection by adrenal corticosteroids and specific antiserum could be additive; (iv) adrenal corticosteroids and specific antiserum acted synergistically with the aminoglycoside antibiotics--no protection was achieved by delayed administration of the steroids or antiserum alone; (v) timing was crucial--the synergistic protective activity of adrenal corticosteroids and of specific antiserum with aminoglycosides declined rapidly as infection progressed; (vi) cyclophosphamide pretreatment markedly impaired the synergistic protective activity of specific antiserum and of adrenal corticosteroids with aminoglycosides; (vii) no reputed anti-endotoxin agents other than adrenal corticosteroids and specific antiserum proved capable of preventing mortality not preventable by aminoglycoside antibiotics alone. These included antisera to rough mutant Enterobacteriaceae of Rc, Rd, and Re chemotypes, anticoagulants (heparin), ascorbic acid, antiproteolytic agents (aprotinin), alpha adrenergic blockers (phenoxybenzamine), prostaglandin synthetase inhibitors (acetylsalicylic acid, sodium salicylate, indomethacin), nicotinamide, glucose, and insulin-glucose-potassium mixtures.

At Duke University Medical Center, 49 patients with proved clostridial myonecrosis were treated with hyperbaric oxygen (HBO) during the past 10 years. Survival in patients with involvement confined to the extremities was 92.3 percent. Survival in patients with combined involvement of extremity and trunk was 53-3 percent, and with primary trunk involvement half of the patients survived. Survival for the entire series was 73.5 percent. Among the 28 patients receiving at least five HBO treatments, 24 survived. Extensive experimental studies were conducted during this same period including in vitro testing and in vivo experimental infections with C. perfringens. Data from the experimental models of gas gangrene indicate a therapeutic benefit with HBO by significantly decreasing both mortality and morbidity rates. The mechanism of action for this appears to be complex but probably includes a direct bactericidal action, bacteriostasis, inhibition of toxin production, and improvement in tissue oxygenation. In the absence of a controlled study, the therapeutic efficacy of HBO in the treatment of clostridial myonecrosis is not fully proved. Nevertheless HBO treatment can be recommended on the bases of sound experimental evidence and the results of favorable clinical experience. Mitigation of this severe but infrequent illness can best be accomplished through prevention, with strict adherence to the principles of wound care.

The potential value of human serum globulin for treatment of patients with the staphylococcal scalded-skin syndrome was determined by measuring the exfoliatin antitoxin content of globulin pools. Of 16 lots tested, only four had detectable antitoxin activity, and in these the levels were minimal. These findings suggest that pooled serum globulin is not a practical source of exfoliatin antitoxin.

Antiserum to the core glycolipid of gram-negative bacteria was prepared by immunization of rabbits with vaccine composed of killed cells of the uridine diphosphate galactose-deficient mutant (J5) of Escherichia coli O:111. Antiserum to J5 not only prevented death of animals from endotoxin but also prevented the local and generalized Shwartzman reactions. Antiserum to endotoxin also prevented renal cortical necrosis and disseminated intravascular coagulation during the evolution of the generalized Shwartzman reaction. Antiserum to be J5 mutant was successful in the treatment of overwhelming bacteremia produced by other gram-negative bacteria; in addition to bacteremia cause by coliform organism, antiserum to J5 was dramatically effective in treatment of bacteremia due to Pseudomonas aeruginosa. One injection of rabbit antiserum to J5 improved the survival rate from 15% in controls to 59% in treated animals (P less than 0.002). Active immunization with J5 vaccine was even more effective against pseudomonas bacteremia: such immunization improved the survival rate from 13% in controls to 92% in vaccinated rabbits. Since an antiserum effective against the J5 mutant of E. coli can be prepared safely in human subjects, such immunotherapy should be considered for patients with gram-negative bacteremia.

The protective effect of high-titer anti-lipid A hyperimmune globulin with respect to the course of the disease and the mortality rate was studied in patients with septicemia verified by positive blood cultures. Six patients were treated with anti-lipid A in an open study. Dramatic improvement in fever curves and clinical condition in some of the patients encouraged us to start a randomized double blind study. So far, 17 patients have entered the study, 16 of whom were evaluable. Immediately after a positive blood culture was found, patients received either high doses of anti-lipid A or placebo (saline solution) on two subsequent days. Before and after each infusion blood samples were taken in order to assess serum bactericidal activity and anti-lipid A titers. Because of the still small numbers of patients the results of both studies were summarized. In all patients treated with anti-lipid A clear-cut increases in anti-lipid A titers were shown. Patients with repeated gram-negative infections showed higher median anti-lipid A titers than patients without such a history. The patients treated with anti-lipid A immune globulin ran a significantly milder course than the placebo group. The severe signs of septic shock were reversed in seven of 15 patients on anti-lipid A compared to two of seven patients treated with placebo. In the anti-lipid A-treated group, three of 15 patients died, and in the placebo group two of seven. This difference is not statistically significant.

The number of toxic substances affecting the nervous system through acute or chronic exposure is overwhelming. This survey will elucidate the possibilities of antidote therapy in some acute cases of poisoning, caused by nervous system toxicants. Antidotes exert their therapeutic effects through a variety of mechanisms: Adsorption, formation of inert complexes, inhibited conversion to toxic metabolites, enhancement of endogenous detoxification, interference at receptor sites, and physiological antagonism. The application of these principles in treating some poisonings caused by important nervous system toxicants will be considered. This survey is by no means comprehensive, but rather gives some relevant examples and deals only with acute poisoning.

A murine monoclonal antibody (15H6) against the trichothecene mycotoxin T-2 was capable of neutralizing the in vitro protein synthesis inhibitory effect of T-2 toxin in human B lymphoblastoid cultures. It was further shown that 15H6 given to rats (250 mg/kg) 30 min before or 15 min after a lethal dose (1 mg/kg) of T-2 toxin conferred 100% survival. A lower dose of 15H6 (125 mg/kg), given 15 min after the lethal dose of T-2 toxin, protected 25% of the rats. An increased time to death and 45% survival was seen in rats given the full dose of 15H6 antibody 60 min after lethal toxin. These data are the first demonstration of effective prophylaxis and therapy for T-2 toxemia.

By means of the lead acetate endotoxin sensitising method it was possible to demonstrate the development of endotoxaemia in tourniquet ischaemia of rats. The lethality of shock was greatly reduced by retreatment with radio-detoxified endotoxin (Tolerin). Prelinary liquidation of the Gram-negative enceroflora caused a similar reduction of lethality. On the basis of the results endotoxaemia of intestinal origin triggered by the vasoactive substances liberated during ischaemia and reaching the circulation are considered of importance in the pathogenesis of tourniquet shock.

Electron-microscopic studies in mice revealed similar and comparable mitochondrial alterations of the liver cells 5-7 days after either a sublethal controlled burn injury or an i.p. injection of an equivalent dose of a burn toxin. Electron microscopy 5 days after i.p. application of different amounts of the burn toxin in rats showed that the extent of the liver alterations correlates directly to the applied dose (occurrence of: cristolysis--intramitochondrial vacuolization--total vacuolar changes of mitochondria(. Controls with the non-toxic/"native" compound isolated from normal skin or excision of a skin piece identical in size to the sublethal burn showed no ultrastructural changes in the liver of mice or rats. In a 2nd series of experiments the therapeutic effect of an antitoxic IgG raised in sheep was tested. The first 3 days after a standard burn or an i.p. injection of 15 mg burn toxin mice obtained 10 mg of the antitoxic IgG (2x/day). Controls injected with the "native" compound or excised as described were treated in the same way. The results showed a specific complete immunological protection from mitochondrial alterations by either the toxin or the burn injury. These results suggest the possibility of an antitoxic IgG-therapy in severe burns.

This article discusses various therapeutic agents that have been used in the treatment of calf diarrhea, such as antibiotics, modulators of intestinal motility, gastrointestinal protectants and absorbents, astringents, agents affecting secretion, steroids, antiadhesives, antitoxins, and monoclonal antibodies. The roles of nutrition and the administration of colostrum following onset of diarrhea are also discussed.