A novel series of highly potent benzimidazole-based microsomal triglyceride transfer protein inhibitors

A series of benzimidazole-based analogues of the potent MTP inhibitor BMS-201038 were discovered. Incorporation of an unsubstituted benzimidazole moiety in place of a piperidine group afforded potent inhibitors of MTP in vitro which were weakly active in vivo. Appropriate substitution on the benzimidazole ring, especially with small alkyl groups, led to dramatic increases in potency, both in a cellular assay of apoB secretion and especially in animal models of cholesterol lowering. The most potent in this series, 3g (BMS-212122), was significantly more potent than BMS-201038 in reducing plasma lipids (cholesterol, VLDL/LDL, TG) in both hamsters and cynomolgus monkeys.

Expression of human hepatic glucokinase in transgenic mice liver results in decreased glucose levels and reduced body weight

Glucokinase is the predominant hexokinase in pancreatic beta-cells and liver parenchymal cells and functions as a critical component of the glucose-sensing apparatus in these glucose-responsive cell types. In the beta-cells, the sensing leads to insulin secretion, while the role in hepatocytes is thought to be in hepatic glucose uptake. To determine the physiological response to an increase in hepatic glucokinase expression, transgenic mice expressing the human hepatic glucokinase gene under the control of a liver-specific human apolipoprotein A-I gene enhancer were generated. Transgenic mice had twofold higher total fasting hepatic glucokinase mRNA, which resulted in a modest 20% increase in fasting glucokinase activity. These animals showed lower fasting plasma glucose, insulin, and lactate levels and improved tolerance to glucose. In addition, glucokinase transgenic animals weighed less and had lower BMI than nontransgenic animals. Thus, glucokinase transgenic animals demonstrate that a modest change in hepatic glucokinase activity enhances the metabolism of glucose.

Relation of vascular oxidative stress, alpha-tocopherol, and hypercholesterolemia to early atherosclerosis in hamsters

A model of early atherosclerosis in hamsters with moderate hypercholesterolemia (217 to 271 mg/dL) was established that was highly responsive to exogenous antioxidants. A key feature of this model was elevation of vascular oxidative stress by use of a diet deficient in nutritional antioxidants and supplemented with corn oil (10%) and cholesterol (0.2%, 0.4%, or 0.8%). After 10 weeks on the 0.4% cholesterol diet, mean plasma alpha-tocopherol levels declined from 5.68 +/- 0.30 to 1.27 +/- 0.15 micrograms/mL, while monocyte-macrophage foam cell lesions in the aortic arch, as assayed by video microscopy/image analysis of oil red O-stained histological specimens, increased from undetectable at week 0 to 60,900 +/- 5400 microns 2 per specimen at week 10 (mean +/- SEM, n = 36). alpha-Tocopherol or probucol administered for 10 weeks markedly suppressed LDL oxidation ex vivo and profoundly inhibited aortic foam cell formation. However, the effects of antioxidants on aortic lesions were attenuated at higher plasma cholesterol levels, although LDL oxidation ex vivo was effectively inhibited. With a plasma cholesterol level at approximately 250 mg/dL, the maximum effect of alpha-tocopherol on lesion size reached approximately 36% of control value, and the dose for half-maximal effect was approximately 10 mg.kg-1.d-1, which resulted in a plasma alpha-tocopherol value of approximately 20 micrograms/mL. Under these conditions a linear, inverse correlation of aortic lesion size and plasma alpha-tocopherol concentration was observed (n = 68, r = -0.581, P < .001). The data demonstrate that LDL oxidation is a significant component of early atherogenesis in this model but suggest that hyperlipidemia can outweigh the therapeutic effectiveness of antioxidants. The high sensitivity of aortic lesion initiation to alpha-tocopherol in hamsters maintained on moderately hypercholesterolemic diets depleted of endogenous antioxidants demonstrates that vascular oxidative stress can be isolated from other causative factors in an in vivo model of atherosclerosis.

A comparison of serum retinol concentration between human and different species of normo and hypercholesterolemic nonhuman primates fed semi-purified diets with defined amounts of vitamin A

1. Serum retinol and total cholesterol concentrations were determined in several species of nonhuman primates fed semipurified diets. Two species of Old World and three species of New World nonhuman primates were examined. 2. Retinol levels were significantly lower (up to four-fold) in the serum of the smaller New World than the larger Old World animals and the difference could not be explained by differences in dietary make-up. 3. Cholesterol levels were not different between the groups but differed within a species when type of dietary fat was altered. 4. Differences in circulating levels of retinol may reflect differences in levels of retinol binding protein between the groups.