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PubMed1994

Buoyant density of hepatitis C virus recovered from infected hosts: two different features in sucrose equilibrium density-gradient centrifugation related to degree of liver inflammation.

Hepatitis C virus is reported to have a low buoyant density in sucrose. To determine the density of hepatitis C virus in the circulation of infected hosts and its association with the degree of liver inflammation, we examined serum samples from 10 patients who were positive for both hepatitis C virus antibody (C100 antigen) antibody and serum hepatitis C virus RNA. After the serum was ultracentrifuged in sucrose density gradient (10% to 60%), the hepatitis C virus RNA titer in each collected fraction was quantified by means of competitive reverse transcription-polymerase chain reaction. In samples from five blood donors, the hepatitis C virus RNA titer had a single peak at fractions with densities of 1.08 to 1.11 gm/ml. In samples from five patients with ALT abnormalities, the titer had two peaks at fractions with 1.09 to 1.10 gm/ml and 1.22 to 1.25 gm/ml. After the selected samples were treated with detergents and ultracentrifuged, the titer in the 1.08 to 1.11 gm/ml fractions decreased and that in the 1.22 to 1.25 gm fractions increased. This result implied that the hepatitis C virus density changed with removal of the viral envelope by lipid solvents. Thus the buoyant density of hepatitis C virus in sucrose was 1.08 to 1.11 gm/ml for an intact virion and 1.22 to 1.25 gm/ml for what was presumed to be a nucleocapsid. These results demonstrated that HCV virion is a dominant form in the circulation of blood donors without ALT abnormalities. In patients with liver inflammation HCV particles with higher densities of 1.22 to 1.25 gm/ml coexist with virion in the circulation, which might be presumed nucleocapsids.

Adolescent↗
PubMed1979

The calculation of some physical parameters of proteins from sucrose density gradient centrifugation data.

A simplified procedure is described for the calculation of protein physical parameters from data obtained by sucrose density gradient centrifugation. The position of an uncharacterized protein relative to standard proteins is determined after centrifugation through linear 5-20% sucrose gradients prepared in both H2O and D2O. From these data, together with the density of each 5% sucrose buffer, the partial specific volume and standard sedimentation coefficient can be calculated without knowledge of rotor dimensions, angular velocity, time of centrifugation, or solvent viscosity. In the absence of specific solvent-induced changes in protein composition or conformation, the magnitude of error due to the approximations inherent in the method is estimated to be less than 2.3% in partial specific volume or less than 10-15% in sedimentation coefficient.

Centrifugation, Density Gradient↗
PubMed1980

Utility of density gradient centrifugation for fractionation of leukemic bone marrow.

Comparison of the distribution pattern of leukemic and normal bone marrow cells, obtained by density gradient centrifugation, may give information about the location of the blockade in the differentiation pathway from stem cell to mature leukocyte, as is supposed to exist in acute leukemia. As a control group 12 children with acute lymphoblastic leukemia (ALL), in complete remission and after cessation of all antileukemic therapy, were studied. By centrifugation over a discontinuous bovine serum albumin (BSA) density gradient, good reproducibility of the partition of the bone marrow cell population was obtained, with a peak in the more dense region. The cells capable of incorporation of [3H] thymidine in vitro were present predominantly in the lower density range. In 9 patients with lympho- or myeloproliferative malignancies (3 with o-cell ALL, 2 with T-cell malignant lymphoma, 1 with B-cell malignant lymphoma, 3 with various malignancies of the myeloid-monocytoid series) similar fractionation on the BSA gradient revealed a different cell partition pattern as compared with the control group. The peak of the distribution curve was located in the less dense region. Highest [3H] thymidine incorporation values were measured in vitro with cells from the lower density region. At last the importance of purely practical considerations in the choice of material for density gradient fractionation is stressed. Application of density gradient centrifugation methods could probably be helpful in attributing to cells from acute leukemia a place in the normal differentiation pathway.

Bone Marrow↗