Correlation of an estrogen receptor-related phosphoprotein with histopathological features in breast cancer

A series of 65 cases of different histological types of breast carcinoma was investigated for the immunohistochemical location of the estrogen receptor-related, 29 kD phosphoprotein using the ER-D5 monoclonal antibody. The ER-D5 response is heterogeneous in relation to some therapeutic limitations and is correlated with histopathological features of the tumors and survival. The main parameters for evaluation of breast cancers are reviewed, both those that are statistically correlated and those that are not apparently always correlated but are known to have considerable biological meaning, such as the ER-status of tumors.     

Hydrodynamic and optical behavior of DNA molecule in the range of high ionic strength

The hydrodynamic and optical properties (intrinsic viscosity and optical anisotropy of DNA) have been studied at the high ionic strength mu greater than or equal to 1 M. It has been shown that the effective volume of DNA molecule doesn't depend of mu when mu greater than or equal to 1 M. In these conditions the electrostatical interactions in DNA disappear. But thermodynamic excluded volume effects do not depend on mu and play also an important role in this range of mu (mu greater than or equal to 1 M). It has been concluded that the condensation of DNA in solutions of high salt concentration is the result of local denaturation of DNA. It has been shown that the optical anisotropy of DNA increases drastically at mu congruent to 2 M but the persistence length of DNA does not change under these conditions.     

Genetic studies on the acidification capacity of sunflower roots induced under iron stress

Under stress of iron deficiency roots of sunflower (Helianthus annuus L.) increase proton efflux which acidifies the root medium, increase the ferric reducing capacity and the exudation of phenolic compounds. Differences have been found previously among sunflower inbred lines in the capacity of their roots to lower pH and it was also found that this character is under genetic control.This work presents the results of an inheritance study made by crossing two genotypes, one (CMS HA 89) without acidification capacity and another (RHA 271) with it. Plants were grown individually in 75 mL vessels with an aerated solution low in iron. After 4 days, solutions were changed to one without iron and the pH of the medium was measured during the following days. Results from F₁, F₂, and backcross generations can be explained with two pairs of alleles controlling the character, being the relation between alleles of complete dominance at both gene pairs, but either gene, when dominant is epistatic to the other.     

Developmental Transition from Enzymatic to Acid Hydrolysis of Sucrose in Acid Limes (Citrus aurantifolia)

The sucrose breakdown mechanisms in juice sacs of acid lime (Citrus aurantifolia [Christm.] Swing.) were investigated throughout fruit development. All three enzymes of sucrose catabolism (sucrose synthase, acid, and alkaline invertase) are present during the initial stages. The activities of these enzymes declined rapidly and disappeared by stage 5 (80% development) but not before vacuolar pH had decreased to approximately 2.5. At this stage, sucrose breakdown occurs by acid hydrolysis. By attaining a vacuolar pH of 2.5 prior to enzyme disappearance, the cell maintains a continuous ability to break down sucrose throughout ontogeny. Thus, acid limes possess a unique and coordinated system for sucrose breakdown that involves both enzymatic and nonenzymatic pathways.     

A model of cell killing by low-dose-rate radiation including repair of sublethal damage, G2 block, and cell division

A computer model that simulates the killing of exponentially growing cells by low-dose-rate radiation is described. The model incorporates cell killing by single-hit damage and double-hit (sublethal) damage, as well as repair of sublethal damage, delay of cell cycle progression, blockage and increased sensitivity of cells in the G2 phase of the cell cycle, and cell division. Seven cellular parameters determine the rate of cell killing. Initial estimates of most of these parameters can be made from independent experiments. Parameters were obtained that gave the best fit to the data for four cell lines, using constant or variable dose rates, and using as end points either the fraction of single cells forming colonies or the total number of clonogenic cells in a mass culture. Some of the parameters were determined to be insignificant or similar for the four cell lines. The main differences between the cell lines in patterns of cell killing over a range of dose rates appeared to be determined by differences in the values of four of the parameters.     

Expression of different isoenzymes of adenylate deaminase in cultured human muscle cells. Relation to myoadenylate deaminase deficiency.

Adenylate deaminase activity was determined in cultured muscle cells of different maturation grades and muscle biopsies from normal subjects and four patients with a primary myoadenylate deaminase (MAD) deficiency. Adenylate deaminase activity was much lower in cultured human muscle cells than in normal muscle. The activity increased with maturation. The ratio of activities measured at 5 and 2 mM AMP decreased in the order: immature muscle cells greater than more mature muscle cells greater than muscle. Adenylate deaminase activity was detectable in muscle cell cultures of MAD-deficient patients. However, both at 2 and 5 mM AMP this activity was significantly lower than in cultured cells with the same high maturation grade obtained from control subjects, whereas the ratio between the activities at 5 and 2 mM AMP was higher. The observations indicate that transition from a fetal to an adult muscle isoenzyme of adenylate deaminase takes place in human cultured muscle cells during maturation. In cultures obtained from MAD-deficient patients this transition does not occur and only the fetal isoenzyme is present.     

Antibody organization on lipid films. Influence of pH and interchain disulphide reduction.

Two distinct lattice structures are observed for two-dimensional (2-D) antibody organization on phospholipid films. A low-order, small-unit-cell, square lattice is obtained at pH 7 and below for mouse IgE, mouse IgG2a and IgG2b and rabbit IgG. At pH 7.5 and above, the observed lattice structure switches to a large-unit-cell, hexagonal type for rabbit IgG and mouse IgE. Interchain disulphide reduction by exposure to 2 mM-dithiothreitol results in the formation of the compact 2-D lattice for all cases and for all pH conditions.     

Downregulation of the translation elongation factor 2 kinase in Xenopus laevis oocytes at the final stages of oogenesis

Phosphorylation of translation elongation factor 2(eEF-2) by a specific Ca2+/calmodulin-dependent eEF-2 kinase plays an important role in the regulation of protein synthesis in mammalian cells. We show here that an eEF-2 kinase similar to the mammalian enzyme is present in tissues of the amphibian Xenopus laevis. We investigated changes in the activity of eEF-2 kinase in extracts of Xenopus oocytes at different stages of oogenesis. The eEF-2 kinase activity was constant from stage I to stage IV of oogenesis, but dramatically decreased after stage IV. Extracts of fully grown stage-VI oocytes showed no eEF-2 kinase activity. However, when extracts were analyzed by two-dimensional gel electrophoresis, eEF-2 was found to be present mostly, if not exclusively, in the dephosphorylated form throughout oogenesis. It is suggested that eEF-2 kinase disappears late in oogenesis to make protein synthesis insensitive to changes in intracellular Ca2+ concentration. This may be important for the induction of meiotic maturation.     

YAC cloning of DNA embedded in an agarose matrix

Yeast artificial chromosome (YAC) cloning of DNA in agarose is an alternative method to cloning from aqueous solutions. It minimizes any shearing that may result from handling of high molecular weight DNA and can be done with nanogram to microgram amounts of material, which facilitates construction of YACs from sources of DNA other than genomic DNA isolated from cells. The average size of the YACs recovered (200-1000 kb) and efficiency of transformation of ligation products (200-1000 cfu/micrograms) are similar to those reported using aqueous protocols. This method has been used to construct chromosome specific YACs, and it should be possible to apply the technique to the construction of chromosome specific libraries using flow sorted chromosomes as source material, and the cloning of restriction fragments isolated by preparative pulsed field gel electrophoresis.