This document only includes an excerpt of the corresponding thesis or dissertation. To request a digital scan of the full text, please contact the Ruth Lilly Medical Library's Interlibrary Loan Department (rlmlill@iu.edu).

No description available.

No description available.

No description available.

No description available.

No description available.

The objective of this study was to assess the potential role of extracellular, cytosolic, and membrane cholesterol in the proliferation and differentiation of bovine myoblasts. In the first experiment, myoblasts isolated from Angus or Angus crossbred steers were cultured with 2% lipoprotein deficient fetal calf serum (LPDS) or normal fetal calf serum. Culturing with LPDS did not alter the cytosolic or membrane cholesterol content, or myoblast differentiation, but inhibited myoblast proliferation, compared to culturing with normal fetal calf serum. In the second experiment, myoblasts were cultured with or without lovastatin, a selective inhibitor of cholesterol synthesis. Culturing with 5 μM lovastatin did not affect medium concentration of cholesterol, but reduced cytosolic and membrane cholesterol contents, compared to culturing with vehicle control. Culturing with 5 μM lovastatin inhibited both myoblast proliferation and differentiation. In the third experiment, myoblasts were cultured with or without methyl-βcyclodextrin (MβCD), a chemical that depletes cholesterol from cell membranes. Treating myoblasts with 10 mM MβCD for 30 minutes reduced membrane and cytosolic cholesterol contents while increasing medium cholesterol concentration. Treating with MβCD inhibited both myoblast proliferation and differentiation compared to treating with vehicle control. Overall, this study showed that lovastatin- or MβCD-induced reductions in cytosolic and membrane cholesterol contents were associated with reduced proliferation and differentiation in bovine myoblasts. These associations suggest that cytosolic cholesterol, membrane cholesterol, or both may play a role in bovine myoblast proliferation and differentiation. / Master of Science / The objective of this study was to assess the potential role of extracellular, cytosolic, and membrane cholesterol in the proliferation and differentiation of bovine myoblasts. In the first experiment, myoblasts isolated from Angus or Angus crossbred steers were cultured with 2% lipoprotein deficient fetal calf serum (LPDS) or normal fetal calf serum. Culturing with LPDS did not alter the cytosolic or membrane cholesterol content, or myoblast differentiation, but inhibited myoblast proliferation, compared to culturing with normal fetal calf serum. In the second experiment, myoblasts were cultured with or without lovastatin, a selective inhibitor of cholesterol synthesis. Culturing with 5 μM lovastatin did not affect medium concentration of cholesterol, but reduced cytosolic and membrane cholesterol contents, compared to culturing with vehicle control. Culturing with 5 μM lovastatin inhibited both myoblast proliferation and differentiation. In the third experiment, myoblasts were cultured with or without methyl-β-cyclodextrin (MβCD), a chemical that depletes cholesterol from cell membranes. Treating myoblasts with 10 mM MβCD for 30 minutes reduced membrane and cytosolic cholesterol contents while increasing medium cholesterol concentration. Treating with MβCD inhibited both myoblast proliferation and differentiation compared to treating with vehicle control. Overall, this study showed that lovastatin- or MβCD-induced reductions in cytosolic and membrane cholesterol contents were associated with reduced proliferation and differentiation in bovine myoblasts. These associations suggest that cytosolic cholesterol, membrane cholesterol, or both may play a role in bovine myoblast proliferation and differentiation.

The aim of this thesis is to assess the influence of the polyunsaturated fatty acids, especially DHA and EPA in the diet on the animal organism in accordance to the levels of total HDL and LDL cholesterol and triglycerides in plasma. As experimental animals were used rats and they were divided into 3 groups of 10 pieces: control group with the addition of 6 % Carthamus tinctorius (n-6 flares), the group with the addition of 6 % fish oil (n-3: EPA, DHA fish) and the group with 6 % addition of oil from Schizochytrium (n-3: DHA, DHA). After 40 days the animals were putted to death according to relevant regulations. Blood lipids were obtained from blood samples by spectrophotometry. Value of polyunsaturated fatty acids of n-3 and n-6 was set by gas chromatography in the liver, muscle and adipose tissue. In accordance to the increase of content n-3 PUFA in group with fish oil and with oil from Schizochytrium, total and LDL cholesterol was reduced in comparison of samples in control group. In comparison to the control group were TAG reduced only in the group with addition of oil.

Most types of hypercholesterolemia are of polygenic origin. Some genes related to hypercholesterolemia are known, although all genes responsible for cholesterolemia regulation have not been characterised yet. To identify these new genes, animal models with spontaneous defects in cholesterol metabolism could be very useful. Moreover, a number of variations and polymorphisms have been found to influence blood cholesterol levels in humans. Some may also affect cholesterolemia responsiveness to dietary fat. The Prague hereditary hypercholesterolemic (PHHC) rat is a unique model of hypercholesterolemia induced by dietary cholesterol alone (without administration of cholic acid or thyrotoxic drugs). It exhibits modestly increased cholesterolemia when fed chow and responds to a diet containing cholesterol with a several-fold increase of cholesterolemia to concentrations comparable to those observed in hypercholesterolemic patients. Hypercholesterolemia in this model is characterised by accumulation of very low density lipoproteins (VLDL) and intermediate density lipoproteins (IDL) enriched by cholesterol. In an experiment with tyloxapol (an inhibitor of lipoprotein lipase) we found that PHHC rats on a cholesterol diet incorporated twice as much cholesterol into VLDL as Wistar rats, although liver...

Cholesterol 7-hydroxylase (CYP7A1) is the rate limiting enzyme of the classical pathway of bile acid (BA) synthesis, which catabolizes approximately half of cholesterol in man. Determination of CYP7A enzymatic activity is a key subject of lipid metabolism research. Direct determination of CYP7A1 activity in hepatic biopsy is mostly not allowed for ethical reasons, so indirect methods are used with serum markers such as 7α-hydroxy-4-cholestene-3- one (C4). The first, methodical aim of the work was to convert the introduced HPLC method for the determination of C4 to LC-MS in order to increase the sensitivity. We focused on the solid phase extraction step, adjusting the composition and volumes of the washing and elution solution. By converting the method from HPLC to LC-MS, the sensitivity was increased approximately 7 times (LD = 1.39 ng/ml). In the second, clinical part of our work, we attempted to confirm the preliminary results of our laboratory on the distribution of C4 in lipoprotein fractions (LPP) in order to find parameter that would correlate with CYP7A1 activity better than C4 level itself. Preliminary results (performed in healthy individuals) showed that most of C4 is carried on HDL, and that the C4 distribution within LPP fractions is similar among examined subjects. We repeated the...