Using a novel small-angle X-ray scattering (SAXS) method for determination of fractional and subfractional composition of lipoproteins (LPs), a significant elevation of total cholesterol-lipoproteins (C-LP) and, especially, total triglyceridelipoproteins (TG-LP), was shown in this work. Among the LP fractions, poloxamer 407 was shown to significantly increase proatherogenic total C-LDL, TG-LDL and, especially, their precursors C-VLDL and TG-VLDL, while only exhibiting a moderate increase in the antiatherogenic C-HDL and TG-HDL fractions. With regard to the VLDL subfractions, significant elevations were observed in both subfractions studied; namely, C-VLDL 1-2 and C-VLDL 3-5 . Similar changes were noted in the TG-VLDL 1-2 and TG-VLDL 3-5 subfractions. The C-IDL and TG-IDL subfractions were increased significantly (20-to 30-fold), while the C-LDL 1-3 subfraction was moderately (3-to 5-fold) increased at 48 hrs and at day 4. In the moderately elevated (2-to 4-fold) anti-atherogenic HDL fraction, the C-HDL 2 subfraction was increased more significantly (4-fold) compared to the C-HDL 3 subfraction; however, both C-HDL subfractions returned to baseline by day 4. The elevation in the TG-HDL 2 subfraction was observed only at 24 hrs. Mouse models of hyperlipidemia and atherosclerosis are useful to evaluate the role of "individual" LPs, as well as their fractions and subfractions, in hyperlipidemia and the genesis of atherosclerosis.

The concentration of tissue inhibitor of type 1 metalloproteinases in blood serum from intact CBA mice measured by enzyme immunoassay is similar to that in healthy humans. The concentration of tissue inhibitor of type 1 metalloproteinases in mouse bile was higher than in blood serum, while its concentration in liver homogenate more than 1000-fold exceeded that in the serum, which attests to its primarily intracellular localization in the liver. Loading of liver cell lysosomes with Triton WR-1339 and development of intrahepatic cholestasis did not affect the concentration of tissue inhibitor of type 1 metalloproteinases in liver homogenate and bile. Administration of CCl4 to mice for 4.5 weeks was accompanied by an increase in the concentration of tissue inhibitor of type 1 metalloproteinases in blood serum, but not in liver homogenate. These changes reflect dysregulation of metalloproteinases, development of inflammation, and progression of the initial stage of connective tissue formation in mouse liver.

Lysosomal enzyme activity in the bile and blood serum was compared in mice with experimental intrahepatic cholestasis induced by alpha-naphthyl isothiocyanate and Triton WR 1339. Triton WR 1339 increases the synthesis of cholesterol (fatty acid precursor) in liver cells. The development of intrahepatic cholestasis was confirmed by the increase in activities of alkaline phosphatase and gamma-glutamyltransferase in blood serum. Administration of Triton WR 1339 in a dose of 100 mg/100 g was followed by a 10-fold increase in beta-galactosidase activity (hepatocyte lysosomal enzyme) in the bile, but not in the serum of mice. beta-Galactosidase activity significantly increased in the bile, but decreased in the serum of mice after treatment with a-naphthyl isothiocyanate in a dose of 200 mg/kg. Our results indicate that intrahepatic cholestasis is manifested in increased secretion of lysosomal glycosidases into the bile. Bile components can aggravate damage to liver cells by affecting the processes of hepatocyte apoptosis and necrosis.

We studied the role of selective suppression of liver Kupffer cells (gadolinium chloride, 14 mg/kg intravenously) in the development of intrahepatic cholestasis in CBA/C57B1/6 mice after intraperitoneal injection of alpha-naphthylisothiocyanate in a single dose of 200 mg/kg. Pretreatment with gadolinium chloride increased the severity of cholestasis and signs of liver damage. Gadolinium accumulation in the liver peaked after 24 h and was accompanied by a decrease in activities of cathepsin D and cathepsin B and concentration of matrix metalloprotease-2. Our results confirm the hypothesis that normal function of Kupffer cells and extracellular matrix plays an important role in cholestasis. Administration of gadolinium chloride serves as a convenient model to study the side effects, toxicity, and safety of lanthanides as nanoparticles.