Search PubMed⌕ Search

Biomedical subjects

C Chandler

Publications and source records attributed to C Chandler.

65 records · Page 4Linked to original sources
PubMed1982

ATP sulfurylase from higher plants : purification and preliminary kinetics studies on the cabbage leaf enzyme.

ATP sulfurylase was purified extensively from green cabbage (Brassica capitata L.) leaf. The enzyme appears to be an asymmetric dimer composed of 57,000 dalton subunits. Initial velocity and product inhibition studies of the forward and reverse reactions point to an obligately ordered kinetic mechanism with MgATP adding before MoO(4) (2-) (or SO(4) (2-)). and MgPPi leaving before AMP + MoO(4) (2-) (or adenosine-5'-phosphosulfate [APS]). The addition of excess purified fungal APS kinase to assay mixtures increased the rate of (35)SO(4) (2-) incorporation and MgPPi formation and extended the linearity of the forward reaction. This effect can be ascribed to the continual removal of APS, a potent product inhibitor of ATP sulfurylase. The specific activities of the enzyme in the APS synthesis, molybdolysis, MgATP synthesis, and sulfate-dependent [(32)P]-MgPPi-MgATP exchange assays were 3.3, 38, 38, and 4.3 micromole product formed per minute per milligram protein, respectively.

Journal Article↗
PubMed1979

DNA binding, induction of unscheduled DNA synthesis, and excision of anthramycin from DNA in normal and repair-deficient human fibroblasts.

The reaction of the antitumor antibiotic anthramycin with cellular DNA and the ability of normal human fibroblasts cells and xeroderma pigmentosum (XP) cells to respond to this injury has been evaluated. The binding of [15-3H]anthramycin to cellular DNA in human skin fibroblasts occurred in a linear manner up to 6 h. Treatment with unlabeled antibiotic resulted in unscheduled (repair) DNA synthesis in human skin fibroblasts maintained in hydroxyurea, whereas negligible unscheduled DNA synthesis was observed in cells of an excision-defective strain of XP. Confluent nondividing normal skin fibroblast cells were able to remove 86% of the bound anthramycin within 72 h, however XP cells were only able to remove 49% during the same incubation period. These results are discussed in terms of the types of DNA damage produced by anthramycin in vitro and the likely repair pathways involved in removing lesions produced on DNA by anthramycin.

Anthramycin↗
PubMed1975

Cell surface lipids and adhesion. III. The effects on cell adhesion of changes in plasmalemmal lipids.

The two preceding papers of this series suggest that the state of the plasmalemmal lipids affects cell adhesion. Plasmalemmal composition was altered by the experimental incorporation of fatty acids into R1 and R2 positions in the phosphatidyl components of the cell surface. In this paper we report that: (1) If the incorporation is of long chain length fatty acids (saturated) cell adhesion rises. (2) If the incorporation is of unsaturated fatty acids cell adhesion falls as the unsaturation increases. (3) Incorporation has to be extensive to produce a large change in adhesion. (4) Changes in adhesion parallel the plasmalemmal incorporation but do not follow the total cell incorporation. Item (4) argues that it is plasmalemmal and not other membrane lipids that are involved in cell adhesion. Item (3) suggests that bulk membrane properties and not some very specific grouping are involved in the effects of lipids on adhesion. The similar extents of incorporation of the various different fatty acids and the negligible amounts of lysophospholipids in the membranes of cells that have incorporated fatty acids argue that the effects are not due to differential accumulations of these lysolipids when incubations are done with different fatty acids. The changes in adhesion cannot be accounted for by changes in surface charge density since the electrophoretic mobility of the cells is unchanged by these incubations. It is suggested that these effects on adhesion due to changes in plasmalemmal lipids can be explained either in terms of the action of intermembrane van der Waals--London (electrodynamic) forces in cell adhesion or of changes in surface fluidity. These alternatives are discussed.

Adenosine Triphosphate↗
PubMedDate not supplied

Hysterectomy following sterilization.

In a review of 108 cases of consecutively selected women undergoing hysterectomy for nonmalignant disease, it was found that one third of the patients or their husbands had previously been sterilized. In many instances, the gynecologic problem necessitating hysterectomy antedated the sterilizing procedure. It is postulated that, when couples request sterilization, two operations might be avoided if routine consideration were given to any condition that might lead to hysterectomy.

Adult↗