Actions of gamma-radiation on resealed erythrocyte ghosts. A comparison with intact erythrocytes and a study of the effects of oxygen

With respect to both permeability and inactivation of membranous GAPDH, ghosts were more susceptible than erythrocytes to free radicals produced in the gamma-irradiation of aqueous solutions. The rate of increase in the permeability of irradiated ghosts was immeasurably greater than that of irradiated erythrocytes, while the rate of inactivation of GAPDH was 21-fold greater. The sensitivity of ghosts to radiation damage was affected strongly by the presence of oxygen during irradiation. In the presence of air, the rates of increase of permeability and inactivation of GAPDH were 2.8- and 1.5-fold of those in the presence of N2. The use of buffer saturated with oxygen accelerated the aerobic rates of increase of permeability and inactivation of GAPDH by 60- and 2.7-fold. These results indicate that inactivation of GAPDH is somewhat sensitive to oxygen, particularly at high concentration of oxygen. Nevertheless, in air or under nitrogen, the rate of enzymic inactivation was almost an order of magnitude greater than that of increase of permeability, indicating that the former is much more sensitive to irradiation. The major mechanism of the oxygen effect observed is the ability of oxygen to increase the branching of the free radical chain reactions which propagate damage after initiation within the membrane.

Acinic cell tumors of salivary gland origin

The acinic cell tumor of salivary gland origin, once thought to be benign, is now known to be an incidiously slow growing malignant neoplasm with lethal potential. While the degree of malignant behavior of individual acinic cell tumors is notably variable, all must be treated with aggression. Traditional and current methods of treatment are reviewed; and, in conjunction with the tumors herein reported, guidelines for managment of this uncommon malignancy are suggested. Four cases have been reviewed in detail and critically analyzed. The pathology, including features of both light and electron microscopy, in included--particularly in relation to the oncocytoid areas identified in from 10% to 40% of the parenchymal cells of our tumors. Since an accurate histopathologic diagnosis is the first step in the establishment of a proper treatment plan, pitfalls in histologic diagnosis have been stressed.

Isolation and characterization of bacteria that grow on methane and organic compounds as sole sources of carbon and energy

Bacteria capable of growth on methane and a variety of complex organic substrates as sole sources of carbon and energy have been isolated. Conditions used to rigorously establish the purity of the cultures are described. One facultative methylotroph has been studied in detail. This organism has peripherally arranged pairs of intracytoplasmic membranes characteristic of obligate methylotrophs. This isolate apparently utilizes the serine pathway of formaldehyde fixation. The location of methane oxidizers in a dimictic lake indicates that these organisms prefer less than saturating levels of dissolved oxygen. Laboratory experiments confirmed the preference of these organisms for atmospheres containing less oxygen than air.

Increase in glyoxylate shunt enzymes during cellular morphogenesis in Myxococcus xanthus

Isocitrate lyase (EC. 4.1.3.1) and malate synthase (EC. 4.1.3.2) increase during microcyst formation in Myxococcus xanthus. The increase in activity is inhibited by chloramphenicol and actinomycin-D.