Cell proliferation in the thymus of Ehrlich ascites tumor bearing mice.

Thymic involution of Ehrlich ascites tumor bearing Swiss and NMRI mice was associated with an increased incorporation of 3H-thymidine into thymus DNA and an enhanced activity of adenosine deaminase. The apparent depletion time constants, which were determined by the following time course of the retention of 3H-DNA, indicated that the rate cell depletion was increased in the thymus of tumor bearing mice. The results suggest that the thymic involution was correlated with an increased proliferative activity and an accelerated depletion of thymic cells.

The effects of thymomodulin and thymolymphotropin on the stress response of neuroendocrine system by gamma-irradiated Wistar rat.

Thymomodulin and Thymolymphotropin, biologically active thymus derivative peptides exert recovery effects on the functionality of some membrane bound, mitochondrial and lysosomal enzymes (monoamine oxidase, ATPase, phosphatases, cytochrome oxidase, succinate oxidase) affected by gamma-irradiation. These drugs exert antistress effect by re-establishing the function of hypothalamus-pituitary-adrenal axis and that of lymphoid organs.

High order packing of DNA as revealed by autodigestion of chromatin in small intestine cell nuclei.

Small intestine cell nuclei incubated in sucrose media released large fractions of DNA into the culture medium. This effect was partially or completely suppressed when incubation was carried out in the presence of a protease inhibitor, 10 to 30 mM NaHSO3. The DNA released in sucrose media containing NaHSO3 was precipitated as a DNA-protein complex by increasing the bivalent ion concentration to 10 mM Ca2+ or 20 mM Mg2+. Most of the released DNA was not precipitated by Ca2+ or Mg2+ when incubation was performed without NaHSO3. As determined by viscosity measurements the mean molecular weight of the DNA released in the absence of NaHSO3 was from 3.5-8.0 x 10(5) and increased to about 11 x 10(5) (corresponding to 8 nucleosomes) when the incubation mixture contained NaHSO3. End group analysis indicated that the DNA segments were terminated by 3'-OH groups. It is suggested that fragmentation of DNA in chromatin was produced by a endogenous alkaline endonuclease activity which was present in the fraction of released DNA. The data support the view that the third-order repeat structure of chromatin consists of subunits containing 8 nucleosomes.

Cell kinetics in the spleen of Ehrlich ascites tumor-bearing mice.

During the period of 18 days after transplantation the uptake of 3H-thymidine into DNA was significantly increased in the spleen of Ehrlich ascites tumor-bearing Swiss and NMRI mice. Adenosine deaminase activity was within the control limits in tumor-bearing Swiss mice and significantly increased for the tumor-bearers of the NMRI strain. However, the increase in the DNA content, which is associated to splenic hyperplasia, was evident only for the Swiss strain. The time course of the retention of 3H-DNA revealed that the half life of spleen cells ranged from 41 to 46 h in normal and tumor-bearing Swiss mice and normal NMRI mice. For tumor-bearing NMRI mice the rate of cell depletion was significantly increased (t1/2 = 32h) compared with that found in normal NMRI mice (t1/2 =44 h). The mean survival time was 23.0 days for the tumor-bearing Swiss mice and 24.6 days for the NMRI mice. These data suggest that the immune responses were similar in both strains of mice, although cell kinetics was different in the spleen of tumor-bearing Swiss and NMRI mice.

Autoradiographic changes in the kidney of the whole-body sublethally x-ray irradiated rat.

203Hg-hydroxymersalyl uptake / gram of kidney (HU), renal autoradiographic and histologic aspect after 800 R X-ray whole-body rat irradiation was studied. Twenty-four to seventy-two hours after irradiation, HU increased, while tubular autoradiographic granularity decreased. Their return to the control levels occurred gradually within two weeks. The relations of these findings to the early circulatory and dystrophic changes, as well as to the subsequent postirradiation restoring renal process are discussed.

Alkaline endonuclease(s) activity in the thymus and spleen of normal and irradiated mice.

Evidence has been found on an alkaline endonuclease activity in the cytoplasmic and nuclear fraction isolated from the thymus and spleen mice. The chromatin-associated endonuclease activity was identified only in the spleen. The enzyme(s) was active on both single- and double-stranded DNA, but the reaction was faster if single-stranded DNA was used as a substrate. Maximum activity was found in the pH range of 7.9 to 8.1 in the presence of 10 mM Mg2+ and 1 mM Ca2+. The enzyme(s) splits DNA, yielding 3'-hydroxyl terminated polynucleotides. It is suggested that this alkaline endonuclease(s) is responsible for the formation of deoxyribopolynucleotides in the thymus and spleen of irradiated mice.

Recovery response of dividing cells in the thymus of whole-body gamma-irradiated mice.

Mice were irradiated with different doses of gamma-rays 30 min after the administration of 32P-orthophosphate. The dose-response curves determined at 72 hours after exposure showed an inflection point in the total activity present in the DNA in thymus and spleen. In the low dose-range, the dose-response curves have D0 = 55 rad (n = 2-5) for thymus and DO = 95 rad (n = 2-5) for the spleen. Thirty minutes after the administration of 32P-orthophosphate, the dividing cells from thymus were partially synchronized by the administration of 80 mg per kg body-weight hydroxyurea. At different time-intervals, the mice were irradiated with 80 rad, and the total activity of DNA was determined at 72 hours after synchronization. A significant maximum of recovery was found at 5 hours (S phase) after the administration of hydroxyurea. In similar conditions, the dose-response curves corresponding to the G1, S and M phase of the division cycle were also determined. The synchronization of dividing cells induced by hydroxyurea failed in the spleen.

The effects of leucotrofina or timolimfotropina on some parameters of carbohydrate metabolism in the Wistar rat.

A 10 days Leucotrofina or Timolimfotropina administration induced in Wistar rats a rise of glycemia and liver glycogen content, and a decrease of glycogen-phosphorylase a activity. These modifications lasted in time and may be due to an activation of the hepatic gluconcogenetic pathway, via a stimulated glucocorticoid production.

Effects of leucotrofina and timolimfotropina on the liver of Wistar rats.

Adult male rats were treated for 10 days with a thymic extract (Leucotrofina-L, or Timolimfotropina-T, Ellem Milano, Italy), in a daily dose of 0.1 ml/100g body weight. 5 days after the end of the treatment, rats were sacrificed and liver was removed. The modifications in the liver were of the same direction for noth thymic extracts (an increase of the total protein content and of DNA concentration and a decrease of RNA concentration).

Morphological behaviour of lympho-myeloid organs at experimental stimulation with leukotrophine.

The influence of leukotrophine on the behaviour of lymphomyeloid organs was studied in male Swiss mice aged 2 months. In the four comparatively studied groups it was shown that leukopoiesis and immune maturation was slightly stimulated by leukotrophine or protected by thiola, a radioprotective substance; the administration of both substances, leukotrophine + thiola, enhances the two actions, myelo-lymphoid leukopoiesis and cellular pyroninophilia, almost doubling them. Histochemical studies were supplemented with histoenzymatic and cytogenetic investigations.

Hematologic and histologic experimental investigations on the therapeutic effect of leukotrophin.

The paper aims at evidencing the stimulating effect on hematopoietic stem cells exerted by the thymus extract "Leukotrophin", prepared by Ellem Laboratory, Milan, Italy. Investigation of the hematologic and histologic parameters allowed the follow up of alterations occurring in bone marrow, blood and tissues of the irradiated animals, treated and untreated as compared with the unirradiated and untreated controls. Regeneration was more active in the groups of animals irradiated and treated with Leukotrophin than in the irradiated and untreated controls. A maximal regeneration of the myeloid series, prevalently of the erythrocytic line, was found 9 days after irradiation.

Release and retention of labelled DNA in the thymus and spleen of irradiated mice.

The process of release and retention of labelled DNA in thymus and spleen of normal and irradiated (60Co) mice has been studied after administration of 3H-thymidine. The results indicate that the dividing fraction of lymphoid cells is more resistant to radiation than the fraction of nondividing lymphocytes. The time courses of the specific activities of DNA in thymus and spleen were different especially after irradiation with lethal doses. It is suggested that the process of depletion in the lymphoid series is probably similar for both thymus and spleen but, the different cellular composition of these organs led to apparently unrelated results.

Effect of cortisol on the release and retention of labelled DNA in the thymus and spleen of mice.

The lymphocytolytic effect of different doses of cortisol was studied in the thymus and spleen of mice previously injected with 3H-thymidine. The results indicate that in thymus the fraction of labelled cells was more resistant to cortisol than the unlabelled cell population. The release of DNA into the fraction of DNA soluble in 0.14 M NaC1 was delayed suggesting that cortisol controls indirectly the lymphocytolytic process. Up to 24 hours after administration of cortisol the loss of labelled spleen cells significantly exceeded the loss of unlabelled cells. The time course of the release of labelled DNA into the fraction of DNA soluble in 0.14 M NaC1 indicates that a fraction of labelled DNA was rapidly removed from the spleen after injection of cortisol.

Evidence for reproductive death of dividing cells in thymus and spleen following whole-body gamma-irradiation of mice.

Mice were given whole-body gamma-irradiation with 300 and 800 rad 1 hour or 1 day after the administration of 3H-thymidine. The time-course of the specific activity of DNA in thymus and spleen and the release of radioactivity into the fraction of DNA soluble in 0-14 N NaCl were determined for 28 hours after exposure. The results indicate that on average the loss of mitotically-active cells was delayed compared with the loss of a representative fraction of non-dividing cells. This suggested that different mechanisms might be implicated in the dying process of the dividing and non-dividing lymphoid cells. Using a dose-fractionation method, the total activity of DNA was determined in thymus and spleen at 24 hours after the first exposure and 25 hours after the in vivo labelling of DNA. A parallelism has been found between the results of this experiment and the recovery effect of the Elkind-Sutton type. It may be concluded that the dying process responsible for the loss of the dividing cells from thymus and spleen after irradiation probably involves reproductive death.

Effects of irradiation on the release and retention of labelled DNA in the small intestine of mice.

Mice were whole-body irradiated with 300, 500 and 800 rd (60Co) one hour or three days after administration of 3H-thymidine. The time courses of the total and specific activity of DNA indicate that three days after exposure with 500 and 800 rd the mitotically active cells were selectively lost from the small intestine. The release of labelled DNA was determined in the fraction of DNA soluble in 0.14 N NaCl. The results suggest that the relatively small fraction of soluble DNA belongs to the mitotically active cells probably having died in the interphase.

Thymic and suprarenalian response of Wistar rats following the administration of the humoral thymic factor (Leucotrofina) and of the cytostatic cyclophosphamide.

Leucotrofina administration in Wistar rats induced in thymus an increase of total protein content and of protein synthesis from 14C-leucine, simultaneously with a raise in the AlAT activity. Adrenal glands were not affected. Leucotrofina administration on the background of Cyclophosphamide induced modifications restored at normal values some of the thymic parameters (total protein content and RNA content) but the ascorbic acid content in the adrenals remained lowered.

Influence of thymic humoral factor(s) on haemopoiesis in mice.

Postirradiation administration of Leukotrophin to whole-body irradiated mice was associated with increased LD50/30 and DRF. As indicated by 59Fe uptake and ESC number, haemopoiesis was significantly stimulated in spleen and bone marrow after Leukotrophin application to irradiated mice. DNA content and the uptake of 3H-thymidine in DNA was significantly enhanced in the thymus and bone marrow of irradiated and Leukotrophin-treated mice. The micronucleus test confirmed that Leukotrophin is a therapeutic agents, while administered before irradiation it does not influence the initial radio-lesions.

Improvement of perfusion flow in the isolated rat liver under the influence of streptase. Autohistoradiographic aspects of 125I-labelled fibrinogen deposition.

The dynamics of the fibrinoplastic process were studied in rat isolated liver, perfused in normothermia with a synthetical medium. For the autohistoradiographical study, 125I-labelled fibrinogen was added to the perfusing medium. The historadiograms obtained suggest that the main link in the rise of trans-hepatic vascular resistance is thickening of the fibrin muff of the sinusoids. Consequent reduction of the capillary permeability determines favourable conditions for stasis and massive precipitation of fibrinogen under the form of fibrin thrombi into the intrahepatic vessels. Streptase addition to the perfusion medium prevents the intervention of these mechanisms during the studied period.