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PubMed1984

Purification of a DNA polymerase-DNA primase complex from calf thymus glands.

An immunoabsorbent column, prepared by covalently linking mouse monoclonal anti-calf thymus DNA polymerase-alpha to Protein A-Sepharose, was used as the primary purification step for rapid isolation of DNA polymerase-alpha from calf thymus-gland extracts. In a 4-step procedure consisting of the removal of nucleic acids by protamine sulfate precipitation, chromatography on the immunoabsorbent column, desalting on Sephadex G-50, and removal of bovine immunoglobulins on Protein A-Sepharose, DNA polymerase-alpha activity was purified about 5000-fold from the crude extract with greater than 40% recovery of total enzyme activity. The antibody column-purified DNA polymerase-alpha fraction contains a DNA primase activity that is efficient in replication of single-stranded DNA and poly(dT) when rNTPs are included in the replication reactions. Synthesis by calf thymus DNA polymerase-primase is totally dependent on added template. Complete replication of circular single-stranded phage DNA is achieved with polymerase-primase producing a nicked circular DNA containing oligoribonucleotide primer in the final product. Primers synthesized with single-stranded phage DNA as template were up to 10 nucleotides long when dNTPs were omitted from the reaction and 8 or less nucleotides long when dNTPs were present. Primers synthesized using poly(dT) consisted of three populations when dATP was absent from the reaction, averaging 20 nucleotides, 10 nucleotides, and 3-4 nucleotides. The 20-nucleotide population was not found when dATP was included in the reaction.

Animals↗
PubMedDate not supplied

A comparative study on the immunological effects of bovine and porcine thymic extracts: induction of lymphoproliferative response and enhancement of interleukin-2, gamma-interferon and tumor necrotic factor production in vitro on cord blood lymphocytes.

Forty samples of cord blood lymphocytes were isolated from 40 normal healthy full-term newborns. The initial 20 samples were used to determine the dose-response curve of three different thymic extracts (TP-1, bovine thymic extract; TG-15-I and TG-15-II, both porcine thymic extracts) and one of renal origin (KG-1) as a control of non-lymphoid organ extract, by measuring the E-rosette T cells. Results showed that E-rosette T cells increased significantly when the thymic extract concentration was increased to 12.5 micrograms/ml. However, there was no statistical difference between TP-1, TG-15-I and TG-15-II in the increase of E-rosette-forming cells. The remaining 20 samples were preincubated with 0, 12.5, 25 or 50 micrograms/ml of thymic extracts. It was observed that the lymphoproliferation, interleukin-2 (IL-2), gamma-interferon (IFN-gamma) and tumor necrotic factor (TNF) production were all significantly increased after thymic extract treatment. No statistical difference between these three thymic preparations in the stimulation of lymphoproliferative response was found. However, among the three thymic extracts, TP-1 appears to induce the highest amounts of IL-2, IFN-gamma and TNF. Of the TG-15-I and TG-15-II, the former stimulates higher IL-2 production whereas the latter enhances IFN-gamma and TNF production. The different immunostimulating effects and potencies that these three thymic extracts showed may reflect not only the species difference but also the difference in preparation procedures. Different components in these thymic extracts may be responsible for different biological activities. Results from these comparative studies may provide useful information in future clinical trials for the treatment of the primary immunodeficiency diseases according to their pathogenesis and may also indicate a possible beneficial effect of the combination of chemotherapy and thymic extracts.

Animals↗
PubMedDate not supplied

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).

Adjuvants, Immunologic↗
PubMed2003

"Action-at-a distance" of a new DNA oxidative damage product 6-furfuryl-adenine (kinetin) on template properties of modified DNA.

N(6)-furfuryladenine (kinetin, K) was shown to have cytokinin activity and antiageing effects. It also appears to protect DNA against oxidative damage mediated by the Fenton reaction. Kinetin was identified as a natural component of DNA in plant extract, calf thymus DNA, fresh DNA preparations from human cell culture, as well as in human urine. A proposed mechanism of kinetin synthesis includes furfural, the oxidative damage product of a 2-deoxyribose moiety of DNA, which reacts with an adenine residue to form N(6)-furfuryladenine at DNA level. The identification of kinetin in plant cell extracts, as well as human urine, suggests its excision from DNA by repair mechanisms. Since such a bulky modification as kinetin induces conformational changes of DNA, this could lead to mutations. Therefore, it was interesting to analyze an effect of kinetin on coding properties of DNA. Chemically synthesized oligodeoxynucleotide (20-mer) containing kinetin AAAACTGCCGTCCTGAKGAT was used as a primer. It was elongated in a polymerase chain reaction (PCR) on a template plasmid pEW1 harboring a 210-bp fragment of DNA derived from the 5' end of HIV mRNA. The PCR product of that length containing kinetin in position 17 from the 5' end was isolated and sequenced. Interestingly, DNA polymerase correctly incorporates thymine opposite of kinetin (an adenine derivative) on the complementary strand, but the misincorporations occur in a vicinity of the modified base.

Adenine↗
PubMed1976

Radioimmunoassay for intact Gross mouse leukemia virus.

A radioimmunoassay for intact Gross leukemia virus has been developed using 125I-labeled Gross virus grown in tissue culture and guinea pig antisera to Gross virus grown either in tissue culture or harvested from leukemic C3H(f) mice. Separation of bound from free labeled virus was effected using the double antibody method. The assay can detect fewer than 10(8) virus particles and has been used to measure the viral content of individual organs from inoculated leukemic C3H(f) mice and from Ak mice with spontaneous leukemia. Organs from noninoculated healthy C3H(f) mice crossreacted poorly in the system, virus generally being detectable only in the thymus and spleen and at low concentration. In some of the inoculated C3H(f) leukemic mice the viral content of as little as 0.5 mul of plasma is measurable. That this assay is for intact virus and not for soluble antigens of the viral envelope was proven by the observation that the immunoreactive material of plasma and extracts from thymus and liver of leukemic mice has a buoyant denisty in sucrose of 1.17-1.18 g/ml, corresponding to that of intact virus grown in tissue culture. With this sensitivity it may now be possible to quantitate viral concentrations in tissue and body fluids from the time of inoculation through the development of obvious pathology.

AKR murine leukemia virus↗
PubMed1984

Controlled trial of a thymic hormone extract (Thymostimulin) in 'autoimmune' chronic active hepatitis.

A randomised controlled trial of thymic hormone extracts (Thymostimulin) (1 mg/kg/day for seven days; 1 mg/kg/weekly thereafter) was undertaken in 30 patients (21 women, nine men) with treated, apparently inactive 'autoimmune' chronic active hepatitis during withdrawal of maintenance corticosteroid and azathioprine therapy. Reactivation of disease occurred in 26 patients (86%) during or after treatment withdrawal and was as frequent in the Thymostimulin treated (11 of 13; 84%) and untreated (15 of 17; 88%; p greater than 0.05) groups. Reactivation of disease was accompanied by a severe defect in concanavalin A induced suppressor cell activity, the magnitude of which was similar in the Thymostimulin treated and untreated groups (mean % suppression = 16.4 and 3.2 respectively; p greater than 0.05 vs 84.4 in control subjects). Further studies assessing the optimal dose, duration of treatment, and mode of administration are required to establish a therapeutic role for thymic hormone extracts in 'autoimmune' chronic active hepatitis.

Adult↗
PubMed1978

Specific antigens of chicken thymus.

Purified plasma membranes from chicken thymus and bursa cells were prepared and solubilized with sarkosyl (sodium salt of N-methyl-N-(1-oxodecyl)-glycine). Antisera to solubilized thymus plasma membrane (TPM) were produced in rabbits and the globulin fraction obtained by ammonium sulfate precipitation. Four precipitating antigens were detected in solubilized TPM by immunoelectrophoresis. Following absorption with chicken serum and bursa plasma membrane (BPM) immunosorbents, three antigens, designated T1, T2, T3, were specific for the TPM fraction, and one antigen, T1, was found in soluble extracts of thymus tissue. Absorption with isolated plasma membrane and whole cells indicated that the T1 and T2 antigens in solubilized TPM are associated with the plasma membrane but not expressed on the surface of the cell. A common antigen, designated BT, was detected in BPM and TPM fractions and in membrane preparations of spleen. The antigens were not detected in any other tissues or cells including brain, circulating lymphocytes and erythrocytes.

Animals↗
PubMed1980

Thymic hormonal activity on human peripheral blood lymphocytes, in vitro. I. Reciprocal effect on T and B rosette formation.

One hour incubation with the thymic extract TP-1 induced reciprocal effect on B and T rosette formation in lymphocytes of human peripheral blood. The percentage of mouse erythrocyte rosette-forming cells among lymphocytes of chronic lymphatic leukaemia was decreased by TP-1 from 54.5% to 27.1% (P < 0.001). No such effect was observed in healthy adult or cord blood lymphocytes. On the other hand, the percentage of sheep erythrocyte rosette forming cells increased significantly after TP-1 treatment, but only under conditions of active rosette formation and not in the total rosette assay. This increase was highly significant in three conditions with relative deficiency of cell-mediated immunity: newborns (17.1 to 28.3%), cancer patients (24.5 to 31.7%) and patients with lepromatous leprosy (19.8 to 31.8%). Only a small increase was noticed in healthy adults. A similarly prepared spleen extract was not active in either B or T rosette assays.

Adult↗
PubMed1981

[Preliminary results on the effects of pretreatment with thymic extract on experimental endotoxin hepatitis in the mouse].

The Authors wish to examine the protective effects which a period of pre-treatment with thymostimulin, would have on endotoxin hepatitis, induced in thymectomized and non-thymectomized animals. The test showed that the histological picture and the degree of endotoxinemia, measured with the Lymulus test, benefited from treatment with a thymic extract. This therapy was effect (and was statistically significant) in obtaining an immunorestoring effect (in the thymectomized mouse) and in inducing an immunostimulating effect (in the normal mouse).

Animals↗
PubMed1978

Sequential precipitation of mouse thymocyte extracts with anti-Lyt-2 and anti-Lyt-3 sera. I. Lyt-2.1 and Lyt-3.1 antigenic determinants reside on separable molecular species.

Anti-Lyt-2.1 and anti-Lyt-3.1 sera were employed for sequential precipitation of NP-40 extracts of 125I-labeled C57BL/6-Lyt-2a, Lyt-3a thymocytes (Lyt-2.1, Lyt-3.1) to determine whether these alloantigenic determinants are present on the same or different molecular species. Treatment of extracts with anti-Lyt-3.1 serum and SaCI completely precipitated both Lyt-3.1 and Lyt-2.1-specific components, whereas treatment with anti-Lyt-2.1 serum reduced by approximately 37% the quantity of labeled species subsequently precipitable by anti-Lyt-3.1 serum. When 125I-labeled thymocytes were subjected to mild trypsinization before NP-40 extraction, the quantity of radioactive components precipitated by anti-Lyt-2.1 serum was essentially unchanged, but that of anti-Lyt-3.1-precipitable components was greatly reduced. Moreover, sequential precipitation of extracts of trypsinized thymocytes with anti-Lyt-2.1 and anti-Lyt-3.1 sera demonstrated that these molecular species were precipitated independently. Thus 1) Lyt-2.1 and Lyt-3.1 antigenic determinants appear to reside on different molecular species; 2) some Lyt-2.1- and Lyt-3.1-positive molecules appear to be complexed with each other in the NP-40 extract; and 3) this association of Lyt-2.1- and Lyt-3.1-positive species was dependent upon components that were labile to trypsinization of intact thymocytes.

Absorption↗