No abstract

In a 9-wk feeding trial, juvenile shrimp (Penaeus monodon) were fed semipurified diets containing seven levels (0, 20, 40, 60, 80, 160 and 320 mg/kg diet) of supplemental thiamin hydrochloride. The dietary thiamin level required for optimal growth in P. monodon was found to be approximately 14 mg/kg diet based on hemolymph (blood) thiamin analysis. The minimum dietary thiamin level that produced substantial shrimp growth was approximately 13 mg/kg diet. Shrimp fed unsupplemented diets (thiamin content of 0.12 mg/kg diet) did not demonstrate specific deficiency signs, except those universal signs such as retarded growth, poor food conversion and low survival rates.

In the blood of 15 patients with yusho or "polychlorinated biphenyl poisoning" that occurred in 1979 in Taiwan, was found polychlorinated dibenzofurans (14 of 15) and polychlorinated quaterphenyls (15 of 15), as well as polychlorinated biphenyls (15 of 15). The mean concentration ratio of these substances was approximately 1 : 160 : 500. Based on the following evidence, we propose that polychlorinated quaterphenyls were major pathogenic substances in the development of yusho: (1) Clinical manifestations and course of yusho patients are disproportionately severe and persistent for the observed blood levels of polychlorinated biphenyls, while patients who were occupationally exposed to pure polychlorinated biphenyls take characteristically mild and benign clinical course despite polychlorinated biphenyl levels often much higher than those noted in yusho patients; (2) Polychlorinated debenzofurans show a marked tendency to accumulate in the liver, which might explain frequent presence of jaundice and other abdominal symptoms in yusho, which are, again, not observed in those with occupational polychlorinated biphenyl poisoning; (3) Toxicity of polychlorinated dibenzofurans is a hundred to ten thousand times greater than that of polychlorinated biphenyls and polychlorinated quaterphenyls in animal experiments.

Polychlorinated biphenyl (PCB) poisoning causes many physiological abnormalities including immune suppression. Cellular immunity was studied in 30 PCB-poisoned patients and 50 normal human subjects. PCB poisoning caused suppression of cellular immunity such as the delayed-type skin response to streptokinase and streptodornase. The suppression of cellular immunity was correlated with the severity of the disease. Thus evaluation of the immune function may be helpful for the diagnosis of PCB poisoning.