Centrifugal separations can be classified into three categories, namely differential pelleting, rate-zonal centrifugation and isopycnic centrifugation. Although differential pelleting is the most widely used technique, it has only a limited potential for providing the investigator with purified material. Thus only the last two techniques, both of which involve separations on density gradients, ...

Lactoferrin has been identified in rabbit heterophil leukocytes on the basis of its immunological reactivity, electrophoretic mobility, acid-resistant iron-binding properties, and spectral characteristics. Leukocyte lactoferrin was found to be exclusively localized in the specific (secondary) granules, which have been resolved from other subcellular components by zonal differential centrifugati...

Virus-specific complementary ribonucleic acid (RNA) from cells infected with Sendai virus was isolated by a procedure involving hybridization with virion RNA and isopycnic centrifugation of the RNA hybrids. The complementary RNA contained adenylate-rich sequences which sedimented at about 4S.

DNA has been quantitatively extracted from Drosophila melanogaster at various stages of embryonic development and analyzed by isopycnic centrifugation in CsCl and by fractionation on methylated albumin columns. The DNA is composed of three main classes of DNA, as defined by their buoyant density, rho, in CsCl: a bulk DNA, rho = 1.699 g cm(-3), and two satellite DNAs, rho = 1.685 g cm(-3) and rh...

Cell-cycle phase transitions are controlled by cyclin-dependent kinases (Cdks). Key to the regulation of these kinase activities are Cdk inhibitors, proteins that are induced in response to various antiproliferative signals but that can also oscillate during cell-cycle progression, leading to Cdk inactivation. A current dogma is that kinase complexes containing the prototype Cdk inhibitor p21 t...

Procedures are described for the isolation of lipoproteins from human serum by precipitation with polyanions and divalent cations. A mixture of low and very low density lipoproteins can be prepared without ultracentrifugation by precipitation with heparin and either MnCl(2) alone or MgCl(2) plus sucrose. In both cases the precipitation is reversible, selective, and complete. The highly concentr...

Understanding materials with dimensions down to a few nanometers is of major importance for fundamental science as well prospective applications. Structural transformation and phonon-confinement effects in the nanodiamonds (NDs) have been theoretically predicted below 3 nm size. Here, we investigate effect size on surface chemistry, microscopic structure, Raman scattering high-pressure high-tem...

Rat alveolar macrophages separated into four isopycnic fractions on Percoll gradients were functionally heterogeneous in bacterial phagocytosis, intracellular killing, superoxide anion release, and lysosomal enzyme activity but not in hydrogen peroxide release. With increasing alveolar macrophage density, phagocytosis, intracellular killing, superoxide anion release, and lysozyme activity incre...

Separation of smooth membrane vesicles from whole mouse brain by isopycnic centrifugation in discontinuous sucrose density gradients show an increased membrane proliferation in gold sodium thiomalate (GSTM) treated mice. Induction of membrane proliferation by GSTM seems to be an important factor in converting the avirulent Semliki Forest virus infection into a lethal one.