Mildred Pavelec

A SERIAL AUTORADIOGRAPHIC ANALYSIS OF H3-GLYCINE UTILIZATION AND DISTRIBUTION IN THE FEMORA OF GROWING MICE

The localization, distribution and cellular turnover of tritium labeled-glycine were followed and quantitatively assessed autoradiographically in the femora of young mice. Initially the labeled amnino acid was taken up by the cellular phase of the skeletal system, and was observed within cells 15 minutes after isotope administration. Thirty minutes after H3-glycine injection represented the peak of cellular uptake (assessed by autoradiographic grain density over cells). Shortly after cells incorporated H3-gycine, silver grains appeared over newly deposited bone and cartilage matrices. At the surfaces of bone, silver grains were arranged in bands which were followed up to 14 days after H3-glycine administration. These growth bands were found over deeper layers of bone with increasing time. The movement of these bands was illustrated and discussed. Labeling of cartilage matrix was diffuse.

AN AUTORADIOGRAPHIC STUDY OF THE LOCALIZATION AND DISTRIBUTION OF TRITIATED HISTIDINE IN BONE

The localization, distribution and cellular turnover of tritium labeled-histidine was followed autoradiographically in the femora of young mice. Initially the labeled amino acid was taken up by the cellular phase of the skeletal system within the first hour after isotope administration. From 1 to 4 hours, intracellular histidine appeared within newly deposited cartilage and bone matrix. By 14 days skeletal cells had lost their label, however, red blood cells were still labeled at 14 days.

Application and evaluation of the lead-adenosine triphosphatase method in skeletal tissue

Application and evaluation of the lead-ATPase histochemical method in skeletal tissue has demonstrated an intracellular localization of enzyme activity. The skeletal tissue was demineralized for 72 hr in cold 10% aqueous EDTA adjusted to pH 7.2. Frozen sections were cut and placed on cold albumenized slides, oriented, thawed, dried in a cool air stream, and fixed for 10 min in cold (−2 to −3 C) 10% formalin buffered with Na-acetate and adjusted to pH 7.2. The sections were washed, treated with 10% EDTA for 20 min at room temperature, rewashed, and incubated for an optimal period of 30 min at 37 C. in the lead-ATP medium of Wachstein and Meisel. Following incubation the sections were washed, treated for 1 min with 1% (NH4)2S, rewashed, immersed for 30 min in 10% buffered formalin, dehydrated, cleared, and mounted. Evaluation of the substrate specificity suggests that other phosphatases associated with skeletal tissue do not complicate the ATPase reaction.

The influence of temperature on chromosome aberrations in tissue culture: Relation to thermal aging

Chromosome aberrations were scored in V-79 strain Chinese hamster cells grown in vitro. The percent of aberrant mitoses observed in anaphase and early telophase increased significantly with temperature over the range of values between 35° and 40°C. No significant increase in aberration percentage was observed when the culture growth time was extended from 2 to 3 days. The progressive increase in chromosome damage with temperature supports the concept that genetic information is thermally degraded even at temperatures in the normal physiological range. Since an increase in chromosome aberration frequency is correlated with aging, it may be that thermally induced information loss is an important factor in the aging process. However, the dependence of the aberration percentage on temperature is not sufficiently strong to fully explain the thermal loss of proliferative capacity of cells in culture. Additional temperature-dependent processes must occur and may further contribute to the thermal destruction of cellular information.

Autoradiographic Assessment of Proteolytic Enzyme Action Using Skeletal Connective Tissue Matrices

The action of commercially available proteolytic enzymes on skeletal matrices was assessed by autoradiographic analysis of grain counts produced by H3-glycine and H3-histidine labeled tissues. In addition, the influence of formalin in fixing solutions on the digestibility of tissue proteins following collagenase and trypsin treatment was also assessed. The presence of formalin is not recommended for either collagenase or trypsin digestion of tissues, whereas Carnoys fixative is suitable. The sensitivity of the autoradiographic method and standardization of experimental design and procedures allow for the determination of the optimal time required for digestion, as well as, the rate at which a tissue digestive reaction proceeds. Moreover, the method allows for an evaluation and comparison of the potency of enzymes intended for histologic and histochemical studies, using skeletal tissues as the testing model.

A thermodynamic formulation of radiation dose rate.

The relationship between dose of ionizing radiation and any of its biological effects is entirely empirical. Since radiation effects are the results of the addition of free energy to a living syste...