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Biomedical subjects

E Sierra

Publications and source records attributed to E Sierra.

14 recordsLinked to original sources
PubMed1988

Mesodermal cell lineage determination and proto-oncogene expression.

Previously, we have established a rat embryo fibroblastic cell line that is characterized as immortal, nontumorigenic and retains a diploid karyotype. We report here that this cell line will spontaneously differentiate along mesodermal cell lineages to form myotubes and adipocytes. We have isolated and characterized lineage-determined (nondifferentiated) preadipocytes and myoblasts. Using these cell lines we have investigated the expression of proto-oncogenes concomitant with lineage-specific determination. No major changes in proto-oncogene RNA levels were observed that correlated with lineage determination. These results would suggest that none of the 15 proto-oncogenes used in these experiments are involved in mesodermal lineage determination; but this does not rule out the possibility that other proto-oncogenes not tested or currently unknown may be involved. However, these differentiating subclones and nondifferentiating fibroblasts that exhibit a normal karyotype will be an excellent model-system to investigate the molecular basis of cell lineage determination.

Adipose Tissue↗
PubMed1985

Response of cultured IEC-17 normal rat intestinal epithelial cells to X radiation.

The growth parameters and radiosensitivity of normal rat intestinal epithelial cells, IEC-17, were studied. The cells were cultured by standard methods and exposed to an array of doses (1-12 Gy) of 250 kVp X rays. The survival curves generated exhibited no initial shoulder and were bimodal. The Do of the first component was about 0.2 Gy and the second component. 5.0 Gy. The ability of this cell line to repair sublethal lesions was examined by fractionation studies; repair was completed within 60 min after the first dose. When Chinese hamster ovary (CHO) cells were grown under the same conditions used for the IEC-17 cells and then irradiated with single doses, a typical survival curve with a Do of 1.4 Gy was obtained. The survival curves obtained for the IEC-17 cell line are consistent with the response of a morphologically distinct single population containing two functionally separate types of cells.

Animals↗
PubMed1984

An acidic extracellular environment reduces the fixation of radiation damage.

Chinese hamster ovary cells in exponential growth were irradiated with gamma or X rays in an acidic or alkaline extracellular environment. Incubation in acid medium during or after irradiation reduced the degree of fixation of potentially lethal lesions. Fixation and repair of acid-modified damage occurred with a halftime of 9 to 10 min. The rate of repair of sublethal damage was unaffected by hydrogen ion concentration and progressed with a half-time of 30 min. An acid environment modified only survival of exponentially growing cells; unfed plateau-phase cultures were unaffected.

Animals↗
PubMed1983

The repair of sublethal damage in diploid human fibroblasts: a comparison between human and rodent cell lines.

Two diploid cell lines of human origin were irradiated in vitro. Repair of sublethal damage was observed in both lines when they were exposed to a single gamma-ray dose and incubated at 37 degrees C prior to receiving a graded second dose. In addition cells were irradiated at a low dose rate (56 or 76 rad/hr) and survival was compared to that after an acute exposure. A dose-rate effect was demonstrated. Sublethal damage repair was also studied using CHO or V-79 Chinese hamster cells, and the data suggest that the degree of repair is similar in human and rodent cell lines at photon doses up to 500 rad. The repair of sublethal damage can be a significant factor in the survival of human cells in vitro for fractionated doses.

Animals↗
PubMed1982

Studies with encapsulated 125I sources. II. Determination of the relative biological effectiveness using cultured mammalian cells.

Chinese hamster ovary (CHO) cells, in either exponential growth or unfed plateau phase were exposed to graded doses of radiation from Iodine-125 or from Cesium-137 at various dose-rates and the cells were assayed for reproductive integrity. From the patterns of cell survival obtained, the relative biological effectiveness (RBE) of the emission from 125I was determined relative to 137Cs. The RBE determined using cells in exponential growth was found to have a value of about 1.2, which was independent of the level of cell survival and did not vary over the dose-rate range from 7.5 to 53 cGy/hr. Using plateau phase cells the RBE has a constant value of about 1.3 between 13 to 46 cGy/hr, but is closer to 2.0 at lower dose-rates of 5 to 7 cGy/hr.

Animals↗
PubMedDate not supplied

[Selection criteria used in 1,310 patients in ambulatory major surgery].

From October 1990 through March 1992, 1,310 patients underwent surgery on an out-patient basis. Fifty (3.82%) could not be released on the day of surgery, most often because of surgical complications (17), postoperative pain (11), poor screening (9), and nausea and vomiting (8). Screening for out-patient surgery must not be based solely surgical procedure. Factors of social context, personality and associated pathology must also be weighed.

Adolescent↗
PubMedDate not supplied

[Social development and family composition (author's transl)].

Starting from the theory regarding the social behaviour of the child and, on the other hand, from the concept of the family as a cultural and psychological and, in addition, sociological unit, an index of social development for children of 6 to 14 years of age is presented, and which is obtained by adding the process of school adaptation plus the process of learning plus personal attitudes. Having this hypothesis as a working basis, a study has been carried out on a total of 240 pupils (120 males and 120 girls) included in the chronological age of from 6 to 14 and belonging to National Schools in Zaragoza (Spain) and within the on going program of growth and development. Social development has been studied through inquiries of personal application at family level and through the application of psychograms of our own tabulation. The number of children in the family has been related to the aforementioned parameters, five family units having been established: one child, two children, three children, four children, five or more children. The overall result indicates that the index of social development proposed by us is higher in the case of unique children; that it is practically the same for those children whose family unit is of two, three or four children, and is sensibly lesser in children included in the family unit of five or more children.

Adaptation, Psychological↗