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At least 631 records · Page 35Linked to original sources
PubMed1981

[Biochemical characteristics of a vaccine against hepatitis B].

Hepatitis B Vaccine antigen, purified from HBs positive and HBe negative plasma, is constituted of well defined morphological particles, containing two major polypeptides P22 and P27, and without any trace of viral DNA. These criteria guarantee innocuity and purity of this type of vaccine.

Electrophoresis, Polyacrylamide Gel↗
PubMed1997

[The isolation and analysis of lymphoblastoid cell lines from patients with xeroderma pigmentosum and progeria].

Lymphoblastoid cell lines from patients with xeroderma pigmentosum (2 forms) and progeria (unusual form) were established using transformation of peripheral blood lymphocytes by Epstein--Barr virus. The influence of different UV doses on cell vitality, proliferation and cell cycle progression was studied by means of flow cytometry. The cell vitality was determined after incubation of cells with etidium bromide and FDA. We used cytograms with two logarithmic signals (log green/log red) to discriminate the cell cycle status. Cell cultures were used with density of 500,000 cells per 1 ml, previously synchronized at G-phase by the incubation in a medium with low serum content. The effect of UV irradiation was followed during 72 h. Among four analysed cell lines only line XP2SP demonstrated enhanced UV sensitivity, expressed by decreasing of the amount of living cells after the UV dose of 2.5 J/m2 and higher. The cell cycle studies showed that cells were blocked in S-phase and simultaneously the amount of apoptotic cells with both reduced DNA content and ability to bind FDA was seen increased. Similar events were observed in the control line only after the dose of 20 J/m2 and higher.

Cell Line↗
PubMed2005

Surface modification of gold and quantum dot nanoparticles with chitosan for bioapplications.

Gold (Au) and quantum dot (QD) nanoparticles, which have been extensively used in many fields, were encapsulated with a natural polymer, chitosan, to improve their biocompatibility. Characterization was performed using ultraviolet-visible, dynamic light scattering, atomic force microscopy, and transmission electron microscope analyses. It was found that a Au/chitosan ratio of 1:1 and smaller produced chitosan-encapsulated Au nanoparticles of a sufficiently small size, and this result was then applied in the chitosan encapsulation of QDs. The biocompatibility of both types of nanoparticles was assessed in cell culture studies using HT29 human colon carcinoma and NIH 3T3 mouse fibroblast cells. MTT and trypan blue exclusion assays revealed that both chitosan-encapsulated Au nanoparticles and QDs exhibited improved biocompatibility over their bare, nonencapsulated counterparts. Therefore, this study showed that chitosan could be used to encapsulate both Au nanoparticles and QDs in order to enhance their biocompatibility. The approaches developed in this study can also be extended to other nanoparticles for bioapplications as well.

Animals↗
PubMed1976

Localization of 5-methylcytosine in human metaphase chromosomes by immunoelectron microscopy.

Human metaphase chromosomes, fixed in methanol-acetic acid, were ultraviolet irradiated to produce single-stranded regions of chromosomal DNA and treated with anti-5-methylcytidine. Using an immunoperoxidase procedure, regions of antibody binding were readily visualized by light microscopy in the centromeric heterochromatin regions of chromosomes 1, 9, 16, the short arm of chromosome 15, and in the distal portion of the Y. Electron microscopic visualization of the same whole mount chromosome preparations transferred to formvarcoated grids revealed additional details of the distribution and arrangement of 5-methylcytosine. A helical arrangement of 5-methylcytosine residues was seen below the centromere of chromosome 1. The Y chromosome showed a concentration of 5-methylcytosine residues on the distal long arm, and in areas just below and slightly above the centromere. In all the above chromosomes, especially chromosome 15, additional 5-methylcytosine residues were detected as isolated foci along the arms. Our findings support the concept that clusters of similar purine or pyrimidine residues exist along the arms of condensed metaphase chromosomes, with the possibility that concentrations of 5-methylcytosine residues might have been enhanced at the surface of the chromosomes during the condensation process.

Antibodies↗
PubMed1963

HOMOLOGOUS INHIBITION, TOXICITY, AND MULTIPLICITY REACTIVATION WITH ULTRAVIOLET-IRRADIATED VACCINIA VIRUS.

Galasso, G. J. (University of North Carolina, Chapel Hill) and D. G. Sharp. Homologous inhibition, toxicity, and multiplicity reactivation with ultraviolet-irradiated vaccinia virus. J. Bacteriol. 85:1309-1314. 1963.-Vaccinia virus whose plaque-forming capacity had been destroyed by ultraviolet rays (2,537 A) was shown to retard the growth of L cells in tube cultures. At input multiplicities (M) of 0 < M < 10, no interference was detected, but at M >== 100 the irradiated virus particles exerted a strong toxic effect on the L cells in monolayer cultures, affecting the plaque formation by active virus which was added. Multiplicity reactivation occurs in sublethally irradiated vaccinia, as shown by virus particle counts via electron microscopy and plaque counts. It is clearly demonstrated in this system because there is no complicating interference. It sets in at a total virus particle multiplicity of about one, even though the multiplicity of the original plaque-forming particles is much below one.

Animals↗