Increasing the levels of ether-linked lipids in L-M cells by glyceryl ether supplementation depresses growth and choline utilization.

To gain insight into the role of alkyl-linked lipids in biological systems, we added hexadecylglycerol (a precursor of complex ether-linked lipids) to medium required for the growth of L-M cells in culture. L-M fibroblasts cultured through several generations in the presence of hexadecylglycerol grow at a reduced rate. Experimental cells at their sixth passage, with 2 microgram supplement/ml, double at 50% the rate of control cell populations.

Modification of lipid acyl groups by serum deprivation does not affect phorbol ester-induced differentiation of human leukemia cells.

12-O-Tetradecanoylphorbol-13-acetate (TPA), a potent tumor promoter, can induce differentiation of human promyelocytic leukemia cells grown in a serum-free environment. Removal of serum produces altered acyl group composition of cellular phospholipids, most notably, marked decreases in the polyunsaturated fatty acid content. Although higher amounts of TPA are required to induce differentiation in serum-free cell populations, induction assessed by morphological and enzymatic markers in similar to the "macrophage-like' differentiated state reported for cells grown in a serum-rich medium.

Fatty acid metabolism in phorbol ester-differentiating human leukemia cells.

Human promyelocytic leukemia cells (HL-60) undergo differentiation when treated with the tumor promoter, 12-O-tetradecanoylphorbol-13-acetate (TPA). As the primary target for TPA action is membranes, studies were undertaken to determine whether phorbol ester exposure would influence fatty acid metabolism in these cells. In cells incubated with labeled fatty acids for 1 hr, the percentage of distribution of lipid radioactivity is highest in the phospholipid fraction of control cultures, whereas in TPA-supplemented cells, substantially more label is associated with triacylglycerols.

The effect of vibration on digital blood flow.

The effect on digital blood flow of an acute exposure to vibration has been assessed. Vibration in the frequency range 40-200 Hz reduces digital blood flow, the effect being maximal at 120 Hz. Increasing the amplitude of vibration reduces digital blood flow.

Alterations in lipid metabolism induced by 12-O-tetradecanoylphorbol-13-acetate in differentiating human myeloid leukemia cells.

Several aspects of lipid metabolism were evaluated in differentiating human myeloid leukemia (HL-60) cells after treatment with the tumor promoter 12-O-tetradecanoylphorbol-13-acetate. Modifications accompanying the phorbol ester-induced differentiation include an increase in the incorporation of acetate into free fatty acids and neutral lipids, an increase in the amount of neutral glycerolipids, and a selective incorporation of long-chain fatty alcohols into triacylglycerols and ether-linked alkyldiacylglycerols. Additionally, an enhanced stimulation of phospholipid metabolism, as measured by the incorporation of 32P and labeled precursors of the polar head groups, could be detected within 4 hr after treatment of cells with the tumor promoter.

Collagen heterogeneity in normal rabbit cornea. I. Isolation and biochemical characterization of the genetically-distinct collagens.

Limited proteolysis of preparations of mature rabbit cornea with pepsin allows the recovery of approximately 90% of the tissue collagen in soluble form. Using recently described selective precipitation techniques, the soluble cornea collagen can be resolved into two major fractions. The predominant fraction, which accounts for about 95% of the solubilized collagen, was identified by means of solubility properties, electrophoretic and chromatographic properties, as well as amino acid analyses of its constituent chains, as Type I collagen.

Prophylactic use of metronidazole in preventing wound sepsis after elective cholecystectomy.

The effect of intravenous metronidazole as prophylaxis against postoperative wound infection was studied in a prospective, randomized, double-blind controlled trial of 116 patients undergoing elective cholecystectomy. No significant difference was found in the infection rate between the treated and the control groups.

Equilibrium reactions in the feet of children with spastic cerebral palsy and of normal children.

The foot-balancing reactions to posterior and lateral displacement of the body were compared in 20 normal children and 30 children with spastic cerebral palsy. The children were divided into five functional groups in order to describe the normal developmental sequence and to contrast the responses of the feet of the spastic children with those of normal children. Normal children who had been walking for more than six months (advanced walkers) showed adult-like reactions, including ankle and tow dorsiflexion, medial-arch reactions and stepping responses.