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K Khristov

Publications and source records attributed to K Khristov.

10 recordsLinked to original sources
PubMed1980

[Ultrastructural localization of peroxidase activity in experimental thyroid gland tumors].

Thyroid adenomas and carcinomas were induced after continuous (12--15 months) treatment of Wistar rats with methylthiouracyl. Ultrastructural cytochemical technique was used in studying the localization of thyroid peroxydase in different follicular cell structures. In control animals, the enzyme was localized on the ER membranes, the internal lamellae of Golgi's apparatus, the perinuclear membrane, the microvilli and in isolated apically arranged lisosomes and microvesicles. No peroxidase activity was detected in animals, having received one-month methylthiouracyl treatment. This was confirmed also by the chromatographic study, showing the presence of inorganic iodine only. Peroxidase activity was demonstrable in only part of the thyroid adenomas and carcinomas; the enzymes was localized in the same subcellular structures as in control animals. In these tumors a variety of iodine-containing components were also identified, largely of the MIT and DIT group.

Animals↗
PubMed1977

[Condensed and dispersed chromatin in the nuclei of thyroid follicular cells under normal conditions and following thyrotropic stimulation].

The author examined the changes in the nuclear size, in its form and optical density as well as the changes in the condensed and dispersed chromatin of the follicular cells of the thyroid gland after thyroid stimulation by means of the method of scanning cytophotometry. He found that after a 20-day treatment of the animals with methythyouracyl-an agent, which blocks thyroid hormonal synthesis and in this way raised the level of the thyreothropic hormone in circulation, the size of the cell nuclei was increased and at the same time its concentration of DNA was reduced. The amount of the particles of the condensed chromatin after thyreotropic stimulation diminished, but the integral space remained unchanged and the area of the dispersed chromatine was mainly increased. The obtained data are discussed in view of the possibilities of the scanning cytophotometry for evaluation of the functional activity of the cell.

Animals↗
PubMed1976

[Kinetics of proliferation of a mouse tumor cell line originating in the fetal large intestine].

The authors examine the kinetics of cellular proliferation of the cellular line STS, originating from adenocarcinoma, obtained after "spontaneous" malignization of a fragment from fetal colon. The cells of STS grow as a single layer and reach exponential phase on the 48th hour, but stationary phase-on the 96th hour of the culture. Time for doubling the number of the cells TD at the exponential phase of growth is 12 hours. The mitotic index varies from 7% at the exponential phase to 1,3% at the stationary. Time of cellular cycle and its phases, estimated by the curves of the marked mitosis, shows the following values: TGi=5.3 hours, Ts=6 hours, TG2=0.5 hour, TM=1,2 hour, and TC=13 hours. The authors discuss the differences in the data of TC and TD.

Adenocarcinoma↗