Light-induced electron transport pathways in membrane preparations from Rhodopseudomonas capsulata.
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Biomedical subjects
Publications and source records attributed to A Hochman.
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The relatively little attention given in the literature to the problem of pericardial effusion in patients with cancer reflects the general attitude that if this complication is disclosed, the future of the patient is sealed, and therapy will not change his outcome. We challenge this pessimistic approach, and describe here our experience with seven patients with solid tumors, in whom pericardial effusion was diagnosed; one of them is described in detail. We advocate an active and sometimes even an aggressive therapy, which should always be related to the degree of the hemodynamic impairment. If instant relief is indicated, pericardiocentesis should be done; pericardiectomy is the treatment of choice if the fluid reaccumulates rapidly. After overcoming the urgent problem, the underlying disease and the local pericardial condition should be treated; and in our opinion, a combined approach, such as systemic or local chemotherapy, or both, with or without precordial irradiation, will lead to the optimal result.
Forty-four patients with metastatic breast cancer were treated with monthly courses of cyclophosphamide, methotrexate and 5-fluorouracil. Complete remission was achieved in five of the 44 patients (11.4%), partial remission in 17 (38.7%) and stabilization in 19 (43.2%). Progression of the disease was seen in three patients (6.7%). Forty patients are still alive and continue to receive chemotherapy. The main side effects were leukopenia, thrombocytopenia, weakness, nausea and vomiting; all were mild and transient, and were treated symptomatically.
Two fractions of membrane preparations, a heavy and a light one were isolated from mildly broken Rhodopseudomonas capsulata cells. The light fraction which contained vesicles similar to the regular chromatophores obtained by sonication and a heavy fraction which appeared in electron micrographs to consist of cell fragments which were designated as heavy chromatophores and were composed of broken cell envelopes containing closely packed vesicles enclosed within the cytoplasmic membrane. Both types of chromatophores catalyzed photophosphorylation. However, cytochrome c2 could be washed out only from the heavy chromatophores. Photophosphorylation activity which was lost by the removal of the cytochrome could be restored by addition of either cytochrome c2 or phenazine methosulphate. Light induced proton efflux in heavy chromatophores in contrast to proton influx in regular chromatophores. The washed heavy chromatophores did not lose the light induced proton movement. Light induced quenching of 9-aminoacridine and atebrin fluorescence in chromatophores, while the fluorescence was enhanced in the heavy chromatophores. The washing did not affect the fluorescence changes of the heavy chromatophores but caused a reduction of the steady state of the carotenoid absorbance shift. It is suggested that the membrane in the heavy chromatophores is oriented inside out with respect to the membrane in regular chromatophores. Cytochrome c2 which is attached to that side of the membrane facing the outside medium could be removed from the heavy chromatophors and reconstituted to them. The role of cytochrome c2 in photophosphorylation is discussed.
A young patient, suffering from thyroid carcinoma 24 years after radium treatment of the neck, is presented. The cancer appeared in the area which has been irradiated. In the present case, the thyroid was exposed to a relatively low dose of radiation. The importance of ionizing radiation and its carcinogenic effect in the juvenile thyroid are discussed.
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