Blood levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin and gamma-globulins in a follow-up investigation of employees with chloracne.

In a follow-up investigation of 8 employees who partly contracted chloracne between 1973 and 1976, elevated concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD, 'Seveso dioxin') were found in blood lipids. The concentrations measured were between 163 and 1935 pg TCDD/g blood lipids, other 'dioxin' levels being normal or only slightly increased in comparison to the background level in the general population. The cause of this was exposure at work during the manufacture of trichlorophenol (TCP). Apart from high cholesterol levels, there was a conspicuous reduction in gamma-globulins.

Saturated amines and diamines as substrates which inhibit beef liver mitochondrial monoamine oxidase.

Monoamines and diamines of 8-12 carbon atoms initially serve as substrates for purified beef liver monoamine oxidase but then lead to inhibition. The inhibition is not solely the result of aldehyde formation as addition of decylaldehyde does not inhibit benzylamine oxidation. Furthermore, neither the addition of alcohol dehydrogenase and NADH nor of semicarbazide prevent the inhibition of diaminodecane oxidation. The formation of a Schiff base on the enzyme surface resulting in aggregation or occlusion of the enzyme may be a cause of the inhibition. When concentrated enzyme solutions (greater than or equal to 1 mg/ml) are reduced by long-chain amines, 100% O2 causes only partial return of the flavin peak at 450 nm while enzyme activity continues to decrease. Substantial recovery of activity occurs (over a 3-4 week period) when inhibited enzyme is sedimented and resuspended in fresh buffer. These observations are discussed and compared with inhibition observed by other investigators with the substrate phenylethylamine.

[Properties of mitochondrial monoamine oxidase isolated from rabbit brain and liver]. / Svoistva monoaminooksidazy mitokhondrii, izolirovannykh iz mozga i pecheni krolika

The effect of pO2 on the monoamine oxidase activity of mitochondria from rabbit brain and liver was investigated using the substrates tyramine, dopamine, tryptamine and serotonin. The effect of the second substrate (oxygen) was dependent upon the concentration of the first substrate (the amine). At amine concentrations below 50 micronM, the reaction rate as measured by a radiometric assay, was not affected by variations in the pO2. It was found that both phenazine methosulfate (PMS) and chlorpromazine (CPZ) are reversible inhibitors of monoamine oxidase, the former was a potent inhibitor (Ki=3X10(-6) M) and the latter relatively weak (Ki=5X10(-4) M). Inhibition by both compounds was non-competitive with respect to the amine substrate. Imipramine was a weak inhibitor of purified MAO from beef kidney and of the MAO activity of mitochrondria from brain and liver. Using tyramine or dopamine as the substrate (0.5-1.0 mM), inhibition ranging from 6-30% was observed at 5X10(-4) M imipramine. With tryptamine or serotonin (0.5-1.0 mM) as the substrate in the presence of 5X10(-4) M imipramine the drug seemed to have no net effect on MAO activity since the average value in the presence of imipramine for a number of experiences was the same as the average for control experiments. For p-iodo-phenyl-3-p-nitrophenyl tetrazolium chloride, a Ki of 43X10(-6) M was found using dopamine as the substrate and oxygen as the gas phase.