Biochemical and clinical studies have revealed a profound and selective toxic effect of elevated temperatures on tumor cells. Whereas the oxygen uptake of Novikoff hepatoma and Ehrlich ascites carcinoma cells was considerably less at 427deg;C than at 38°C, there was little difference in respiration at these two temperatures in normal and regenerating liver. The inhibition of the respiration of Novikoff hepatoma cells was irreversible after 90 min. There was no significant effect of temperature on anaerobic glycolysis. In 22 patients with cancers of the limbs the temperature in the tumors was raised to 41.5° to 43.5°C for several hours in 25 regional perfusions with prewarmed blood. Severe complications in some patients lead to six deaths and three immediate amputations. Intensive post‐treatment care was required. Three patients failed to respond; four could not be evaluated and all others had regressions. Grossly the tumors disappeared totally in ten patients, of which three recurred. Histological evaluation of multiple biopsies demonstrated complete massive necrosis in eight cases, of which none recurred, although one died and three required amputations; of these, seven are alive and free of disease. In the cases with partial regression, the tumors all recurred and required amputation or other treatment. The most responsive tumor appeared to be melanoma. No conclusions about survivals can be drawn at present although four of seven patients with malignant melanomas treated only by heat perfusion are alive and well with functional limbs 28, 27, 11 and 7 months after treatment. Only one patient has died of metastases although two have been lost to follow‐up.

Highly purified rat liver mitochondria (RLM) when exposed to tert-butylhydroperoxide undergo matrix swelling, membrane potential collapse, and oxidation of glutathione and pyridine nucleotides, all events attributable to the induction of mitochondrial permeability transition. Instead, RLM, if treated with the same or higher amounts of H 2 O 2 or tyramine, are insensitive or only partially sensitive, respectively, to mitochondrial permeability transition. In addition, the block of respiration by antimycin A added to RLM respiring in state 4 conditions, or the addition of H 2 O 2 , results in O 2 generation, which is blocked by the catalase inhibitors aminotriazole or KCN. In this regard, H 2 O 2 decomposition yields molecular oxygen in a 2:1 stoichiometry, consistent with a catalatic mechanism with a rate constant of 0.0346 s ؊1 . The rate of H 2 O 2 consumption is not influenced by respiratory substrates, succinate or glutamate-malate, nor by N-ethylmaleimide, suggesting that cytochrome c oxidase and the glutathione-glutathione peroxidase system are not significantly involved in this process. Instead, H 2 O 2 consumption is considerably inhibited by KCN or aminotriazole, indicating activity by a hemoprotein. All these observations are compatible with the presence of endogenous heme-containing catalase with an activity of 825 ؎ 15 units, which contributes to mitochondrial protection against endogenous or exogenous H 2 O 2 . Mitochondrial catalase in liver most probably represents regulatory control of bioenergetic metabolism, but it may also be proposed for new therapeutic strategies against liver diseases. The constitutive presence of catalase inside mitochondria is demonstrated by several methodological approaches as follows: biochemical fractionating, proteinase K sensitivity, and immunogold electron microscopy on isolated RLM and whole rat liver tissue.Many human diseases, including cancer and other pathologies associated with aging, such as arteriosclerosis and cataracts, are related to mitochondrial dysfunctions provoked by reactive oxygen species (ROS) 2 (1). In this regard, the so-called free radical theory of aging has been proposed (2). ROS are highly reactive and may be extremely toxic in biological systems, as they attack a variety of molecules, including proteins, polyunsaturated lipids, and nucleic acid (3), causing the cell to die by apoptosis or necrosis. In physiological conditions, 1-2% of molecular oxygen consumption during mitochondrial respiration undergoes incomplete reduction by single electrons to form superoxide anion (O 2 . ) at the level of NADH-ubiquinone reductase (complex I) and ubiquinol-cytochrome c reductase (complex III). These two segments of the respiratory chain generate the superoxide radical by autoxidation of reduced flavin and by transferring an electron from reduced ubisemiquinone to molecular oxygen, respectively (4). Superoxide is rapidly converted to hydrogen peroxide by mitochondrial superoxide dismutase, which then produces the highly reactive hydroxyl radical (OH ⅐ ...

The relationships between tertiary structure and copper binding in Pseudomonas fiuorescens azurin have been studied by fluorescence, absorption, and electron paramagnetic resonance spectra. The fluorescence spectrum at neutral

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A novel series of 1-acetyl-3-(4-hydroxy- and 2,4-dihydroxyphenyl)-5-phenyl-4,5-dihydro-(1H)-pyrazole derivatives 1-12 have been synthesized and investigated for the ability to selectively inhibit the activity of the A and B isoforms of monoamine oxidase (MAO). The new synthesized compounds 1-12 proved to be more reversible, potent, and selective inhibitors of MAO-A than of MAO-B. Knowing that stereochemistry may be an important modulator of biological activity, we performed the semipreparative chromatographic enantioseparation of the most potent, selective, and chiral compounds, 6 and 11. The separated enantiomers were then submitted to in vitro biological evaluation while increasing their inhibitory activity and A selectivity. The (-)-6 enantiomer shows K(i(MAO-A)) = 2 nM and SI = 165 000, (+)-6 shows K(i(MAO-A)) = 6 nM and SI = 166 666, (-)-11 shows K(i(MAO-A)) = 4 nM and SI = 80 000, and (+)-11 shows K(i(MAO-A)) = 7 nM and SI = 38 571.