PubMed Health⌕ Search

Biomedical subjects

S Mazur

Publications and source records attributed to S Mazur.

10 recordsLinked to original sources
PubMed1995

Episomal amplification or chromosomal integration of the viral genome: alternative pathways in hamster polyomavirus-induced lymphomas.

The state and expression of the hamster polyomavirus genome in a large panel of virus-induced lymphomas have been investigated. The viral genome is present within tumor cells either as abundant nonrandomly deleted extrachromosomal copies or as a single copy integrated into cellular DNA. We show that these two physical states are likely to be functionally equivalent: first, deletion and integration of the viral genome both inactivate the late coding region; second, the amount of viral early RNAs yielded by a single integrated copy appears to be very similar to that associated with several thousands of extrachromosomal copies of the viral genome. These data underline two essential requisites for hamster polyomavirus to become lymphomagenous: suppression of the late coding functions of the viral genome and expression of the viral oncogenes above a threshold level.

Animals↗
PubMed1989

ATPase activity of the UvrA and UvrAB protein complexes of the Escherichia coli UvrABC endonuclease.

We have analyzed the ATPase activity exhibited by the UvrABC DNA repair complex. The UvrA protein is an ATPase whose lack of DNA dependence may be related to the ATP induced monomer-dimer transitions. ATP induced dimerization may be responsible for the enhanced DNA binding activity observed in the presence of ATP. Although the UvrA ATPase is not stimulated by dsDNA, such DNA can modulate the UvrA ATPase activity by decreases in Km and Vm and alterations in the Ki for ADP and ATP-gamma-S. The induction of such changes upon binding to DNA may be necessary for cooperative interactions of UvrA with UvrB that result in a DNA stimulated ATPase for the UvrAB protein complex. The UvrAB ATPase displays unique kinetic profiles that are dependent on the structure of the DNA effector. These kinetic changes correlate with changes in footprinting patterns, the stabilization of protein complexes on DNA damage and with the expression of helicase activity.

Adenosine Triphosphatases↗
PubMed1986

Mast cells in regional lymph nodes responding to syngeneic and xenogeneic tumour MSVC and HeLa cell lines in BALB/c mice.

In response to primary and secondary stimulation by xenogeneic HeLa carcinoma cells or by syngeneic sarcoma MSVC cells the regional lymph nodes of BALB/c mice are enlarged, however, their absolute mast cells content does not increase and in relative terms a decrease of mast cells concentration is observed. These results are in accordance with our earlier observations that during antigeneic and T-cell mitogen stimulation the lymphatic mast cells population does not increase but is rather reduced. This may indicate the engagement of these cells in delayed-type hypersensitivity.

Animals↗
PubMed1985

Lymphatic mast cells in response to in vitro stimulation by non-specific T-cell mitogens.

Activation of lymph nodes by the T-cell mitogens PHA and Con A is correlated with a depletion of lymphatic mast cells. This result, and our earlier reports on the depletion of mast cells in lymph nodes stimulated by allogeneic and tumour cells, as well as on the elevation of mast cell number in thymus-less 'nude' mice, lead us to the conclusion that antigen- or mitogen-stimulated T lymphocytes produce lymphokine(s) which degranulates mast cells and/or is responsible for their negative chemotaxis.

Animals↗
PubMed1985

Decrease of lymphatic mast cells in response to syngeneic WAMIB tumor cells.

In response to the syngeneic carcinoma cells the regional lymph nodes are enlarged, but their lymphatic Mast Cell content was reduced in both, relative and absolute terms. This result confirms our earlier data on the depletion of lymphatic Mast Cells in the lymph nodes stimulated by various antigens.

Animals↗
PubMed1983

Strain specific transplantable medullar carcinoma in DBA/2W mice.

A solid medullar carcinoma, which arose spontaneously in DBA/2W mouse was passed in vivo in syngeneic and semisyngeneic recipients for ten generations without alteration of its morphology. This cancer, which we named WAMIB, has a relatively slow growth ratio with MST 59 days and can be easily reproduced from cell cultures and/or from cryopreserved tumor fragments. WAMIB tumor is nearly diploid and does not metastasize, does not regress spontaneously and is rejected when grafted into allogeneic recipient animals.

Animals↗
PubMed1980

Crystallinity of human pineal calcospherulites.

Crystallinity of mineral in human pineal calcospherulites was determined by electron spin resonance spectrometry after irradiation of the samples with gamma rays in a 60Co-source. The radiation-induced stable paramagnetic centers in the crystalline lattice of hydroxyapatite crystals were used as a marker of the crystalline fraction and related to the total mineral content. The crystallinity of pineal sand is higher than that of compact bone. The numerical value of the crystallinity coefficient depends on both the average crystal size of hydroxyapatite and the percentage of the crystalline fraction in the total amount of mineral. Literature data show that the average size of hydroxyapatite crystals in pineal sand are smaller than in bone tissue. It is, therefore, concluded that the higher crystallinity of pineal acervuli is due to the lower percentage of the submicrocrystalline fraction in their mineral.

Aged↗