Cell locomotion on differently charged substrates : Effects of substrate charge on locomotive speed of fibroblastic cells

To assess how cell locomotive behavior is influenced by an electrostatic interaction at the cells' contact area, locomotion speeds of mouse fibroblast, L cells, were compared on differently charged non-living substrates. These substrates were prepared by polymerizing bovine serum albumin with glutaraldehyde, and their surface charge was changed by treating them with poly- -lysine or poly- -histidine. The locomotion speeds increased with increasing negativity of the substrate charge. On the less negatively charged substrates, the cells ceased locomotion and did not alter their-positions. In spite of the diversity in the cell behavior, there was little difference in cell growth among the different substrates. When the substrates were treated with trinitrobenzene sulphonic acid (TNBS), which reacts with amino and other cationic groups, the immobilization no longer occurred. This indicates that the substrate charge is a main factor in modulating cell behavior.     

Properties of myosin light chain kinase prepared from rabbit skeletal muscle by an improved method

Myosin light chain kinase was prepared from rabbit skeletal muscle. DEAE-Sephadex, calmodulin-Sepharose 4B affinity gel and Ultrogel AcA 34 were used for the purification. It took 3 days for the preparation, and 6.2 mg of myosin light chain kinase was isolated from 600 g of frozen muscle. The molecular weight of the myosin light chain kinase estimated by sedimentation equilibrium analysis was 103,000 +/- 4,100. The isoelectric point was 5.0. Chemical modification of cysteine residues did not affect the catalytic activity, but modification of tyrosine residues diminished the activity. In order to activate myosin light chain kinase, it was necessary to bind calmodulin in an equimolar ratio and the dissociation constant was estimated to be 3.6 nM. The optimum pH for the catalytic activity was 7.5, and the activity was inhibited by NaCl and KCl. In the presence of 2.74 mg/ml myosin light chain and 75 mM KCl, the catalytic activity was found to be 88 s-1. The Vm and Km at 0.14 M KCl were 100 s-1 and 53 microM, respectively, for the isolated light chain as substrate and 70-80 s-1 and 19 microM for myosin as substrate.     

Cytologic study of tissue repair in human bronchial epithelium

The cytologic findings of atypical cells considered to be tissue repair cells after mechanical injury to the bronchial epithelium are reported. These cells were studied in sequential bronchial brushing smears from patients who underwent repeated bronchoscopies for the diagnosis of lung cancer. The cellular findings varied according to the length of time since the previous bronchial brushing. Many cell clusters of highly atypical cells in two-dimensional sheets with large nuclei and prominent nucleoli were observed in specimens taken two or three days after a previous brushing; mitotic figures were observed on day two. In specimens taken on days four and five, the number of atypical cells was decreased and the degree of atypia was slight.     

Binding of a histidine-rich peptide to Porphyromonas gingivalis

Porphyromonas gingivalis 381 cells were incubated with 125I-histidine-rich polypeptide (histatin) 5 in the presence or absence of unlabeled histatin 5, to evaluate the histatin-binding capacity of the cells. The binding of histatin 5 was rapid, reversible, saturable and specific. The number of histatin 5-binding sites per cell was 3,600, and the dissociation constant (Kd) was in the order of 10(-6) M. These findings suggest that histatin interacts with certain bacterial cells through specific binding sites on their surface, and will allow the development of a histatin radioreceptor assay.