Sterol absorption and sterol balance in phytosterolemia evaluated by deuterium-labeled sterols: effect of sitostanol treatment.

Absorption of dietary cholesterol, campesterol, and sitosterol, cholesterol balance, and fecal excretion of plant sterols were determined in three unrelated patients with phytosterolemia and three healthy volunteers during constant intake of cholesterol and plant sterols using accurate gas-liquid chromatography-mass spectrometry techniques. Each subject received a mixture of [26,26,26,27,27,27-2H6]cholesterol, [6,7,7-2H3]sitostanol, and [6,7,7-2H3]campesterol together with two non-absorbable markers, [5,6,22,23-2H4]sitostanol and chromic oxide. Feces were collected from days 5 to 7 and absorption of different sterols was calculated from the intestinal disappearance of the different sterols relative to [5,6,22,23-2H4]sitostanol and chromic oxide. The results obtained by the two markers were not different and the absorption of cholesterol averaged 53 +/- 4% for the patients (mean +/- SD) and 43 +/- 3% for the volunteers. Campesterol absorption averaged 24 +/- 4% in patients and 16 +/- 3% in healthy volunteers, whereas sitosterol absorption averaged 16 +/- 1% and 5 +/- 1%, respectively. Cholesterol synthesis expressed by body weight varied considerably in the two groups but appeared to be about 5 times lower in patients than in controls. Administration of a high dose of sitostanol (0.5 g t.i.d.) to two patients was followed by a reduction in cholesterol absorption by 24% and 44%, an increase in fecal output of cholesterol and steroids derived from cholesterol and plant steroids, and a marked reduction of serum cholesterol, campesterol, and sitosterol. Under the conditions used, inhibition of cholesterol absorption by sitostanol was not followed by a significant rise in cholesterol synthesis. The time of observation was, however, too short to allow final conclusion on this. The results show that the absolute difference in absorption rate of different sterols between the patients and healthy volunteers was about the same. As a consequence, increasing hydrophobicity causes a relative decrease of absorption rates. Thus, patients with phytosterolemia seem to have a generally increased absorption of sterols rather than a loss of a specific discriminatory mechanism, and oral administration of sitostanol seems to be an interesting new approach for treatment of phytosterolemia.

[Low-dose fish oil in primary hypertriglyceridemia. A randomized placebo-controlled study]. / Niedrig dosiertes Fischöl bei primärer Hypertriglyzeridämie. Eine randomisierte Placebo-kontrollierte Studie.

In a double-blind, randomized, placebo-controlled trial, we prospectively investigated the effects of two low doses of fish oil (10.5 and 5.25 g daily) in capsule form in patients with primary hypertriglyceridemia. During a 6 weeks' therapy with 10.5 g fish oil, serum triglycerides decreased by a mean of 38% from 578 +/- 167 to 358 +/- 66 mg/dl (p less than 0.05). With 5.25 g daily, triglyceride levels fell by 20% from 538 +/- 100 to 431 +/- 64 mg/dl (n.s.). With placebo, triglycerides increased by 8% from 835 +/- 176 to 900 +/- 228 mg/dl (n.s.). Total and HLD-cholesterol levels remained uninfluenced in all groups. Serum alkaline phosphatase decreased by a mean of 12% from 86 +/- 7 to 76 +/- 6 units/l in the patients treated with 10.5 g fish oil (p less than 0.01). Platelet aggregation after induction with collagen was slightly, but significantly inhibited in the patients treated with the higher dose of fish oil. Thus, in patients with primary hypertriglyceridemia, fish oil at a daily dose of 10.5, but not at 5.25 g, led to a significant reduction of serum triglyceride levels and to an inhibition of platelet aggregation.

Donor splice site mutation in the apolipoprotein (Apo) C-II gene (Apo C-IIHamburg) of a patient with Apo C-II deficiency.

The DNA, RNA, and protein of apo C-II have been analyzed in a patient with apo C-II deficiency (apo C-IIHamburg). Markedly reduced levels of plasma and intrahepatic C-II apolipoprotein were demonstrated by immunoblotting and immunohistochemical analysis. Northern, slot blot, and in situ hybridization studies revealed low levels of a normal-sized apo C-II mRNA. No major rearrangement of the apo C-II gene was detected by Southern blotting. Sequence analysis of apo C-II genomic clones revealed a G-to-C substitution within the donor splice site of intron II. This base substitution resulted in the formation of a new Dde I and loss of a Hph I restriction enzyme cleavage site. Amplification of the mutant sequence by the polymerase chain reaction and digestion with Dde I and Hph I restriction enzymes established that the patient was homozygous for the G-to-C mutation. This is the initial report of the DNA sequence of an abnormal apo C-II gene from a patient with deficiency of apo C-II. We propose that this donor splice site mutation is the primary genetic defect that leads to defective splicing and ultimately to an apo C-II deficiency in this kindred.

[Value of echocardiography in the preoperative diagnosis of acute bacterial endocarditis]. / Stellenwert der Echokardiographie in der präoperativen Diagnostik der akuten bakteriellen Endokarditis.

Open-heart surgery was performed in 26 of 56 patients with acute bacterial endocarditis seen in three years. Non-controllable infection, cardiac failure or embolism were the indications for operation. In all instances pre-operative invasive angiographic diagnosis was dispensed with, indications being based entirely upon clinical findings plus the results of M-mode or cross-sectional echocardiography. In 22 of the 26 patients the pre-operative echocardiographic diagnosis coincided with the intra-operative one. In the other four patients the pre-operative echocardiographic findings were incomplete, but no surgically important information had been missed.

Effects of interruption of the enterohepatic circulation of bile acids on the transport of very low density-lipoprotein triglycerides.

An increase in plasma very low density lipoprotein-triglycerides (VLDL-TG) is seen frequently during treatment with bile acid-binding resins. The purpose of this study was to determine whether this increment in VLDL-TG is due mainly to an increase in synthesis of VLDL, or to an enhanced catabolism. Three types of patients were studied: (1) 7 normotriglyceridemic subjects. (2) 4 obese patients, and (3) 9 hypertriglyceridemic patients. Before treatment they underwent a study of VLDL-TG kinetics that employed multicompartmental analysis of specific activity curves following injection of 3H-glycerol. The patients were then treated with a bile acid-binding resin, either cholestyramine or colestipol, for several weeks to several months. At the end of the treatment period, they were readmitted to the hospital for a second study of VLDL-TG kinetics. The patients showed a variable response to resin therapy. Many had an increase in concentrations of VLDL-TG, but others had no change or even a slight decrease. However, analysis of the data showed a high correlation between change in production rates of VLDL-TG and change in concentration. Also, when the data for the 20 patients were combined, there was a statistically significant increase in both synthetic rates and concentrations of VLDL-TG; in contrast, the fractional catabolic rate (FCR) was unchanged by therapy. Therefore, our data show that when treatment with bile acid sequestrants causes an increase in plasma VLDL-TG, the increase is due to an increment in production and not to a decrease in catabolism.

Triglyceride and cholesterol metabolism in primary hypertriglyceridemia.

To determine mechanisms of elevated plasma triglycerides (TG) in patients with primary hypertriglyceridemias, simultaneous studies were carried out on kinetics of very low density lipoprotein-triglycerides (VLDL-TG) and synthesis of cholesterol and bile acids. Sixteen hypertriglyceridemic patients with familial combined hyperlipidemia (FCHL) and 12 patients with poorly classified, primary hypertriglyceridemia were studied, and their results were compared to a series of normal and obese subjects previously studied in our laboratory. The mean value for transport (synthesis) of VLDL-TG in patients with FCHL was about twice normal. Although the upper normal synthesis rates overlapped with transport rates of some patients with FCHL, it appeared that the major cause of hypertriglyceridemia in FCHL was an elevated production of VLDL-TG. However, the height of the plasma TG in FCHL patients also was influenced by individual clearance capacities for VLDL-TG, and fractional clearance rates in several seemed particularly low. Synthesis rates for cholesterol and/or bile acids were high in several patients with FCHL, suggesting simultaneous overproduction of VLDL-TG and sterols; however, increased synthesis of both was not observed in all the patients. Most patients with poorly classified hypertriglyceridemia had over-production of VLDL-TG, but an apparent reduction in clearance was common. In these patients, increased synthesis of cholesterol and bile acids was infrequent. Our results indicate that abnormally high production of VLDL-TG seemed to be the major factor in causing primary hypertriglyceridemia, but that clearance capacity can play an important role in determining the the severity of the TG elevation.