Magnetic resonance imaging of the normal pituitary gland using ultrashort TE (UTE) pulse sequences (REV 1.0).

Introduction: The purpose of this study was to examine the normal pituitary gland in male subjects with ultrashort echo time (TE) pulse sequences, describe its appearance and measure its signal intensity before and after contrast enhancement.

Methods: Eleven male volunteers (mean age 57.1 years; range 36-81 years) were examined with a fat-suppressed ultrashort TE (=0.

Effects of maternal and long-term postnatal protein malnutrition on brain size and composition in rhesus monkeys.

Rhesus monkeys consumed purified diets that supplied either low or adequate levels of protein (3.8 vs. 13.

Metabolism of native and acetylated low density lipoproteins in squirrel monkeys with emphasis on aortas with varying severities of atherosclerosis.

We studied the clearance of 131I-labeled native low density lipoproteins (LDL) and 125I-acetyl LDL from the blood of hypercholesterolemic and atherosclerotic squirrel monkeys which had been fed a semipurified diet supplemented with cholesterol for 3 years and from control monkeys which had been fed the same diet without cholesterol. In agreement with previous observations in other species, acetyl LDL left the circulation much more rapidly than native LDL. The cholesterol supplemented monkeys removed native 131I-LDL to the liver, the major site of clearance of both LDL forms, more slowly than controls.

Different susceptibilities to the formation of cholesterol gallstones in mice.

In the search for an animal model of genetic determinants of cholesterol cholelithiasis, we found strain, gender and individual differences in mice. Male black (C57BL6J) mice had a 50% incidence of cholesterol gallstones after they consumed lithogenic food similar to that used by Tepperman et al. for 2 weeks, whereas similarly treated male agouti (CBA/J) mice and females of both strains were free of gallstones.

Metabolism of [125I]tyramine cellobiose-labeled low density lipoproteins in squirrel monkeys.

Low density lipoproteins labeled with [125I]tyramine cellobiose ([125I]TC-LDL) were removed from the circulation of squirrel monkeys at a similar but slightly slower rate than LDLs labeled with 125I, [125I]hydroxyphenyl propionic acid, or [3H]leucine. After the simultaneous injection of [125I]TC-LDL and [131I]LDL labeled with 131ICl, the 125I was also removed at a slightly slower rate than 131I. Most of the radioactivity was retained in tissues and not excreted during the 24 h after injection of [125I]TC-LDL.

Dietary protein effects on lipoproteins and on sex and thyroid hormones in blood of rhesus monkeys.

We studied plasma lipoprotein and hormone concentrations in rhesus monkeys that had consumed either a low protein (3.8% of kilocalories) or a control protein (13.9%) purified diet since birth (6-10 yr before the beginning of this experiment) in order to test the hypothesis that chronic protein deficiency could influence plasma lipoproteins through an effect on the hepatic metabolism of gonadal or thyroid hormones.

The effects of nutrition on unconjugated plasma bilirubin concentrations in squirrel monkeys.

Bolivian squirrel monkeys (Saimiri sciureus) have fasting unconjugated hyperbilirubinemia (males: 2.0 +/- 0.14; females: 3.

A nonhuman primate model of Gilbert's syndrome.

A Bolivian population of squirrel monkeys, Saimiri sciureus, exhibits several features of Gilbert's syndrome in man, and is proposed as a nonhuman primate model of the condition. The Bolivian population was found to have higher fasting (40.6 +/- 2.

Binding properties of high-density lipoprotein subfractions and low-density lipoproteins to rabbit hepatocytes.

Primary cultures of rabbit hepatocytes which were preincubated for 20 h in a medium containing lipoprotein-deficient serum subsequently bound, internalized and degraded 125I-labeled high-density lipoproteins2 (HDL2). The rate of degradation of HDL2 was constant in incubations from 3 to 25 h. As the concentration of HDL2 in the incubation medium was increased, binding reached saturation.

Interaction of free cholesterol and apoproteins of low and high density lipoproteins with isolated rabbit hepatocytes.

Primary cultures of rabbit hepatocytes were incubated with rabbit high density (HDL) and low density (LDL) lipoproteins in order to compare the surface transfer of free cholesterol with the uptake of apoproteins. Hepatocytes were maintained for various intervals with either LDL or HDL which contained both 125I-labeled protein and free [4-14C]cholesterol. After a 3-hr incubation with an LDL concentration equivalent to 25% of the normal rabbit serum level, the percentage of media 14C in hepatocytes was 2.

Effects of long-term protein deficiency on plasma lipoprotein concentrations and metabolism in rhesus monkeys.

Lipoprotein concentrations and metabolism were studied in 5- and 9-year-old rhesus monkeys (Macaca mulatta). Both age groups had been divided into control (13.8% of the calories as protein) and low-protein (3.

Metabolism of free and esterified cholesterol and apolipoproteins of plasma low and high density lipoproteins.

We studied the patterns of equilibration of free and esterified cholesterol between lipoprotein fractions of plasma separated by heparin-Mn2+ and of their disappearance from plasma and appearance in liver and bile. Free or esterified [4-14C]cholesterol in low density lipoproteins (LDL) and [7(n)-3H]cholesterol in high density lipoproteins (HDL2 or HDL3) were incubated together with plasma or injected simultaneously into squirrel monkeys. The isotope was alternated for successive experiments.

Relationships between cholesterol gallstones, biliary function, and plasma lipoproteins in squirrel monkeys.

We used squirrel monkeys (Saimiri sciureus) as models to investigate human sex differences in susceptibility to cholesterol gallstones, biliary function, and plasma lipoproteins. Cholesterol gallstones developed in a large proportion of intact and gonadectomized male and female Brazilian monkeys maintained on a lithogenic diet, but male Bolivian monkeys were completely resistant. Although the gallbladder bile of nearly all monkeys was saturated with cholesterol, the bile of the Bolivian monkeys had a much greater concentration of total lipids (cholesteriol + phospholipid + bile acids) than did bile of the other groups.

Low density lipoprotein receptors and catabolism in primary cultures of rabbit hepatocytes.

Rabbit 125I-labelled low density lipoproteins (LDL) were incubated with primary monolayer cultures of rabbit hepatocytes in studies designed to assess the role of liver in LDL catabolism at the cellular level. After hepatocytes were preincubated for 20 h in lipoprotein-free medium, they exhibited time- and concentration-dependent interaction with 125I-labelled DLD at concentrations to 1 mg LDL protein/ml and times to 24 h. After a 3 h (37 degrees C) incubation with 50 microgram LDL protein/ml, hepatocytes bound 400 ng (LDL protein)/mg (cell protein), internalized 280 ng/mg, and degraded 660 ng/mg.

Effect of type of dietary fat and cholesterol on cholesterol absorption rate in squirrel monkeys.

To explore the effect of the type of dietary fat and the level of cholesterol on the rate of cholesterol absorption, 13 different male squirrel monkeys were used for 39 different tests. The plasma isotope ratio technique of Zilversmit, which involved the injection of 3H-cholesterol and gastric intubation of 14C-cholesterol, was shown to give reproducible results which compared well with those based on a method involving labeled beta-sitosterol. The percentages of ingested cholesterol that were absorbed showed considerable variation among individuals, but were relatively constant in the same animal.

Triacylglycerol and very low density lipoprotein secretion into plasma of squirrel monkeys.

We determined the effects of varying the types and level of dietary fat and cholesterol on the increase in plasma total triacylglycerol concentrations after injection of Triton WR-1339, an inhibitor of lipoprotein lipase, into monkeys that had been subjected to an overnight fast. The monkeys that had been treated with Triton WR-1339 were then given a test meal by intragastric intubation. Dietary cholesterol, high levels of fat and saturated fat in the habitual diet reduced the rate of release of triacylglycerol to plasma in the fasted monkey.

Influence of lysophosphatidylcholine on the metabolism of plasma lipoproteins.

Both low density lipoproteins and cellular membranes are known to have a high affinity for lysophosphatidylcholine. In this study lysophosphatidylcholine influenced the retention of lipoproteins by arterial tissue in vitro and the rate of disappearance of low density lipoproteins from the blood in vivo. Pieces of aorta from rabbits or rhesus monkeys were successively incubated for 90 min each in 2 or 3 solutions.

The effects of dietary fat and cholesterol on the metabolism of plasma low density lipoprotein apoproteins in squirrel monkeys.

Low density lipoprotein apoproteins from squirrel monkeys (Saimiri sciureus) had characteristic 2-phase die-away curves in plasma. The kinetic constants were similar with three methods of labeling: in vitro with 125I by the iodine monochloride or the Bolton-Hunter methods or in vivo by the injection of [3H]-leucine into a donor animal. Dietary cholesterol and the type of dietary fat influenced the concentration of plasma cholesterol and low density lipoproteins.

The effect of diet on hepatic bile formation and bile acid metabolism in squirrel monkeys with and without cholesterol gallstones.

In order to explain why squirrel monkeys on some experimental diets develop cholesterol gallstones, we made a number of measurements on bile acid kinetics and on bile secretion and composition. The pool size of cholic acid was much greater in monkeys on a commercial diet than in any group on a semipurified diet. It was also greater in squirrel monkeys on a lithogenic diet but without gallstones than in monkeys from the same diet group with gallstones.

Effect of type of dietary fat, cholesterol and chenodeoxycholic acid on gallstone formation, bile acid kinetics and plasma lipids in squirrel monkeys.

To explore the effect of type of dietary fat, cholesterol and chenodeoxycholic acid on gallstone formation, bile formation, bile composition, bile acid kinetics and plasma lipids in squirrel monkeys, 39 monkeys were studied using seven different diets. Safflower oil, a highly unsaturated fat, added to a diet with cholesterol resulted in at least as high an incidence of cholesterol gallstones as butter added to the same diet. On the other hand, diets with high levels of saturated or unsaturated fat without cholesterol did not result in gallstone formation.

Metabolism of lipoproteins in nonhuman primates. Reduced secretion of very low density lipoproteins in squirrel monkeys with diet-induced hypercholesterolemia.

We have studied the effects of diet-induced hypercholesterolemia on the rates of secretion of triglycerides into the plasma of fasted squirrel monkeys. Two groups of monkeys were studied: control animals which were fed a semipurified diet not associated with hyperlipemia (plasma cholesterol 127 +/- 8 mg/100 ml), and animals made hypercholesterolemic (plasma cholesterol 307 +/- 31 mg/100 ml) by being fed a diet containing 25% butter and 0.5% cholesterol.