Chronic ethanol administration alters hepatic surface membranes as evidenced by decreased concanavalin A binding

The effects of chronic ethanol administration on the hepatic surface membrane were examined. The binding of the lectin, concanavalin A (Con A), to isolated hepatocytes was used to ascertain changes in the hepatic plasma membrane, especially in regard to glycoprotein composition, due to chronic ethanol feeding. Hepatocytes, isolated from rats fed ethanol for 5 to 7 weeks, had a decreased ability to bind Con A when compared to hepatocytes from either the pair-fed controls or ad libitum chow-fed rats. Since decreased Con A binding was more apparent at high Con A concentrations, reduced lectin binding likely reflected changes in the composition of surface membrane glycoproteins in the livers of the ethanol-fed rats. When ethanol (50 mM) was added to the incubation medium containing hepatocytes from ethanol-fed rats, pair-fed controls, or chow-fed rats, no effects on Con A binding were observed. These results indicate that chronic ethanol administration induces changes in the oligosaccharide chains of plasma membrane glycoproteins in the liver. Such alterations may play a role in the pathogenesis of alcoholic liver disease.     

The cork oak tree in California

There are 5,000 trees in various parts of the State, planted at various times, and recent experimental strippings of the largest have yielded 600 to 1,000 pounds of high quality cork per tree. Does this presage an American cork industry?     

A novel, convenient assay of lanosterol 14α-demethylase

A rapid and sensitive kinetic assay of lanosterol 14α-demethylation has been developed and analyzed. Three substrates, [32-³H]-24,25-dihydrolanosterol, [32-³H]lanost-8-en-3β,32-diol, and [32-³H]lanost-7-en-3β-32-diol, were studied. In all cases, the rate of tritium released into aqueous solution provided a simple and direct assay of 14α-demethylase activity. The kinetic parameters of K_m and V_max for each substrate have been determined in a reconstituted system from rat liver. The percentage of turnover monitored by the novel tritium release assay was comparable to that observed by conventional GC methods. Separation of unreacted sterol from tritiated formate and water via reverse-phase chromatography permitted several samples to be analyzed at once.     

Colony formation in agar by murine plasmacytoma cells: potentiation by hemopoietic cells and serum

Clonal growth in semisolid agar medium was obtained using cells from 19 of 25 transplanted murine plasmacytomas when the medium was supplemented by whole mouse blood or washed red cells. With different tumors cloning efficiency ranged from 0.01% to 21.6%. With two exceptions, mouse blood did not potentiate colony formation in agar by cells from transplantable myelomonocytic, myeloid, and lymphoid leukemias, reticulum cell sarcomas and fibrosarcomas. The clonal growth of some plasmacytomas was also potentiated by syngeneic thymic, spleen or bone marrow cells. Plasmacytoma colony growth was not stimulated by normal mouse serum but serum from mice injected with endotoxin or polymerised flagellin stimulated colony growth by some plasmacytomas. The active serum factor was not the colony stimulating factor (CSF) and its appearance after antigenic stimulation was not T cell-dependent. Preimmunised mice failed tq respond to antigenic stimulation. Whole body irradiation did not induce a rise in the capacity of serum to stimulate colony formation by plasmacytoma cells.     

Studies on the bone marrow colony stimulating factor (CSF): relation of tissue CSF to serum CSF

Fluctuations in the colony stimulating factor (CSF) content of submaxillary salivary gland, lung, kidney and spleen were studied in male C₅₇BL mice which had been subjected to a variety of stimuli (endotoxin, x-irradiation or polyadenylic-polyuridylic acid complex) that caused elevations of the serum CSF. The temporal relationships and magnitudes of the rises in CSF were complex and differed from tissue to tissue according to the stimulus used. In the tissues examined not only was the measurable CSF content in each case found to equal or exceed the prestimulatory levels, but in some cases distinctly different forms of CSF were observed as shown by differences in the zone sedimentation, electrophoretic, and calcium phosphate binding characteristics of the material. The patterns of response to the stimuli investigated suggested that tissue injury either directly, or indirectly via the release of various cellular constituents, might mediate the release of CSF by various widely disseminated and/or differing cell types.     

Endotoxin-induced size change in bone marrow progenitors of granulocytes and macrophages

Injection of 5 μg endotoxin to adult C₅₇BL mice caused a marked increase in the sedimentation velocity of granulocytic and macrophage progenitor (colony-forming) cells in the bone marrow. This change was maximal two days after injection and was not accompanied by corresponding changes in total marrow nucleated cell populations. The endotoxin-induced shift was not dependent on the presence of the thymus but did not occur in mice challenged after preinjection with endotoxin. No changes in buoyant density, cell cycle status, pattern of differentiation and responsiveness of granulocytic and macrophage progenitor cells were observed after the injection of endotoxin. The increased sedimentation velocity of progenitor cells appears to indicate an increase in cell volume but the mechanisms involved have not been identified.     

How reliable are in vitro clonal cultures? Some comments based on hemopoietic cultures

Clonal cultures in semisolid medium have proved invaluable in analyzing hemopoietic subpopulations and in detecting their specific growth regulators. However, they can be subject to certain deficiencies that an investigator must take care to exclude. These include inabilities of the particular culture system to detect the true stem cells under study or to allow self-generation of clonogenic cells or a full expression of their differentiation potential. Clonal cultures, like conventional cultures, can be subject to significant cell-cell interactions, complicating attempts to characterize the action of a test regulatory molecule. Culture data need to be supplemented by a variety of other data before they can be regarded as valid evidence that a regulatory molecule detected in vitro is likely to function in a similar manner in vivo.