Heterogeneity of cholesterol homeostasis in man. Response to changes in dietary fat quality and cholesterol quantity

Studies were carried out to examine the effects of dietary fat and cholesterol on cholesterol homeostasis in man. 75 12-wk studies were carried out during intake of 35% of calories as either saturated or polyunsaturated fat, first low and then high in dietary cholesterol. Dietary fat and cholesterol intakes, plasma lipid and lipoprotein levels, cholesterol absorption and sterol synthesis in isolated blood mononuclear leukocytes were measured during each diet period. In 69% of the studies the subjects compensated for the increased cholesterol intake by decreasing cholesterol fractional absorption and/or endogenous cholesterol synthesis. When an increase in plasma cholesterol levels was observed there was a failure to suppress endogenous cholesterol synthesis. Plasma cholesterol levels were more sensitive to dietary fat quality than to cholesterol quantity. The results demonstrate that the responses to dietary cholesterol and fat are highly individualized and that most individuals have effective feedback control mechanisms.

Multiple-dose efficacy and safety of an extended-release form of niacin in the management of hyperlipidemia

This multicenter trial evaluated the safety and efficacy of escalating doses of Niaspan (niacin extended-release tablets) and placebo (administered once-a-day at bedtime) in patients with primary hyperlipidemia on the percent change from baseline in levels of low-density lipoprotein (LDL) cholesterol and apolipoprotein B. Extended-release niacin was initiated at a dose of 375 mg/day, raised to 500 mg/day, and further increased in 500-mg increments at 4-week intervals to a maximum of 3,000 mg/day. A total of 131 patients (n = 87, extended-release niacin; n = 44, placebo) were treated for 25 weeks with study medication after a 6-week diet lead-in/drug washout phase and 2-week baseline LDL cholesterol stability phase. Significant decreases from baseline in levels of LDL cholesterol and apolipoprotein B became apparent with the 500-mg/day dose and were consistent at all subsequent doses (p < or =0. 05), reaching 21% and 20%, respectively, at the 3,000-mg/day dose. Significant increases from baseline in levels of high-density lipoprotein cholesterol became apparent with the 500-mg/day dose and were consistent at all subsequent doses (p < or = 0.05), reaching 30% at the 3,000-mg dose. Significant decreases from baseline in triglycerides and lipoprotein(a) occurred at the 1,000-mg dose and were apparent at all subsequent doses (p < or =0.05), reaching 44% and 26%, respectively, at the 3,000-mg dose. The most common adverse events were flushing and gastrointestinal disturbance. Transaminase increases were relatively small, and the proportion of patients who developed liver function abnormalities on extended-release niacin was not significantly different from placebo. Thus, extended-release niacin was generally well tolerated and demonstrated a dose-related ability to alter favorably most elements of the lipid profile.

Dyslipoproteinemia in pediatric systemic lupus erythematosus

Patients with systemic lupus erythematosus are at increased risk for premature atherosclerosis. We examined one possible etiologic factor, dyslipoproteinemia, both before and after corticosteroid therapy. We identified 2 distinct patterns of dyslipoproteinemia. One is attributable to active disease; the other is attributable, in part, to corticosteroid therapy. The dyslipoproteinemia of active disease consists of depressed high density lipoprotein cholesterol and apoprotein A-I with elevated very low density lipoprotein cholesterol and triglyceride, while the dyslipoproteinemia after corticosteroid therapy consists of increased total cholesterol, very low density lipoprotein cholesterol, and triglyceride. The possible pathophysiologic mechanisms responsible for these patterns, as well as the possible roles in premature atherosclerosis seen in systemic lupus erythematosus patients, are discussed.

Effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate metabolism and biomarkers of oxidative stress in men and women with elevated blood pressure

OBJECTIVE

To assess the effects of consuming foods containing oat beta-glucan on blood pressure, carbohydrate homeostasis and biomarkers of oxidative stress.

DESIGN

A randomized, double-blind, controlled clinical trial.

SETTING

The trial was conducted at two clinics.

SUBJECTS AND INTERVENTIONS

Ninety-seven men and women with resting systolic blood pressure 130-179 mm Hg and/or diastolic blood pressure 85-109 mm Hg were randomly assigned to consume foods containing oat beta-glucan or control foods for 12 weeks. Resting blood pressures, insulin and glucose values before and after standard breakfast meals, and four biomarkers of oxidative stress were measured before and at the end of the treatment period.

RESULTS

Changes from baseline to week 12 in mean peak insulin and incremental area under the insulin curve differed significantly between groups (P=0.037 and 0.034, respectively), with the beta-glucan group showing declines and the control group remaining essentially unchanged. Blood pressure responses were not significantly different between groups overall. However, in subjects with body mass index above the median (31.5 kg/m(2)), both systolic (8.3 mm Hg, P=0.008) and diastolic (3.9 mm Hg, P=0.018) blood pressures were lowered in the beta-glucan group compared to controls. No significant differences in biomarkers of oxidative stress were observed between treatments.

CONCLUSIONS

The results of the present trial suggest beneficial effects of foods containing beta-glucan from oats on carbohydrate metabolism, and on blood pressure in obese subjects.

Epidemiology in anaesthesia. III: Mortality risk in patients with coexisting physical disease

The Cardiff Anaesthetic Record System has been used to examine the hospital mortality rates and relative risks for patients having anaesthesia who have certain preoperative conditions coexisting with their disease requiring surgery. Each preoperative condition was associated with a higher mortality rate than occurred in patients with no preoperative condition (for example ischaemic heart disease 7%, diabetes 5.7%, no preoperative condition 0.5%). Mortality was greater for emergency than for elective operations. In contrast to an increasing mortality by age, the relative mortality risk decreased, suggesting that in older age groups coexisting disease may be less important than other risk factors in determining mortality.

Absorption of bile acids from the large bowel in man

The absorption of bile acids from the human large bowel was studied in eight patients. All patients had cholecystitis and cholelithiasis and had to undergo cholecystectomy. Cholic acid-(14)C was injected during surgery into the lumen of the cecum, hepatic flexure of the colon, or transverse colon in six patients, under the visual control of the surgeon. Common duct bile was collected by T tube daily for 5 days, and bile acids were extracted. Significant amounts of radioactivity appeared in T tube bile in each patient. T tube bile acids contained a total of 43.6-84.6% of the administered radioactivity; the average for the six patients was 58.9%. The majority of the tracer was excreted during the first 24 hr. In an additional patient cholic acid-(14)C was given in the form of an enema 5 days postoperatively. In this subject 30.8% of the retained radioactivity was excreted through the T-tube in 48 hr. The labeled cholic acid was recovered as both cholic and deoxycholic acid from T tube bile. Thin-layer chromatographic analysis of the bile acid samples indicated that the fraction of radioactivity recovered as deoxycholate increased with time during the postoperative period. Gas-liquid chromatographic analysis showed that the daily total quantity of excreted bile acids increased significantly from the 1st-5th days of the experiment. The amount of cholate excreted in T tube bile increased markedly with time, that of chenodeoxycholate increased moderately, and that of deoxycholate decreased sharply during the 5 days of the experiment. In three patients, injection of radiopaque material mixed with the tracer showed no evidence of regurgitation into the small bowel by serial X-rays. In an additional patient, tube aspirate from the terminal ileum contained no radioactivity. The results indicate that cholic acid is converted to deoxycholic acid in the human colon, and both of these bile acids are absorbed from the human large bowel in significant amounts. These data establish the previously unproved concept that significant absorption of bile acids takes place from the large bowel of man.

Effects of neomycin on absorption, synthesis, and/or flux of cholesterol in man

The mode of action of the hypocholesteremic drug neomycin (2 g/day) was studied in four patients. All showed a significant reduction in plasma cholesterol concentrations (mean 25 percent, range 18-31 percent), and in one of three patients with hyperglyceridemia there was a decrease of plasma triglycerides of 26 percent. Cholesterol absorption was measured in three of four patients: there was a marked decrease. Sterol balance studies in four patients showed an unabating increase in fecal neutral steroid excretion (mean increase 345 mg/day, range 323-361) for 3-5 wk after plasma cholesterol levels had reached a new and lower plateau. Fecal acidic steroid excretion increased temporarily in two patients, with a sustained increase of 93 mg/day in only one. Daily stool weights increased significantly in three of four patients, though none had steatorrhea; there was a significant reduction in excretion of secondary bile acids; neutral sterol degradation rates were not affected by the drug. Slopes of plasma cholesterol-specific activity time curves did not change. These results fail to support the suggestion that neomycin acts as a bile acid precipitant. The finding of increased fecal neutral steroid excretion is consistent with decreased cholesterol absorption, but also with increased cholesterol absorption, but also with increased cholesterol synthesis (secondary to release of negative feedback control), with increased flux of cholesterol from tissues, or with a combination of all three actions.

Effects of fenofibrate on plasma lipids. Double-blind, multicenter study in patients with type IIA or IIB hyperlipidemia

Of 240 patients with Type IIa and IIb hypercholesterolemia recruited in 11 centers, 227 were randomized to double-blind treatment with either fenofibrate (100 mg three times daily) or matching placebo for 24 weeks. A group of 192 of these patients were studied for a further 24 weeks during which all received fenofibrate in open label fashion. For the 92 Type IIa patients receiving fenofibrate in the double-blind phase, there were significant reductions (p less than 0.01 compared to baseline) in total plasma cholesterol (-18%), LDL-cholesterol (-20%), VLDL-cholesterol (-38%) and total triglycerides (-38%). Mean plasma HDL-cholesterol in these patients increased by 11% (p less than 0.01). With the exception of LDL, which was not high before treatment, similar changes were seen in the 24 fenofibrate-treated Type IIb subjects. Lipid parameters of placebo-treated patients did not change significantly. This pattern of change was repeated in the open period for the 94 patients previously on placebo, while the 98 who had been on fenofibrate remained stable with small further reductions in total and LDL cholesterol (-38% and -5.5% respectively). Adverse effects were some allergic-type skin reactions early in treatment and an occasional increase in transaminases, BUN, or creatinine. The results were similar to those obtained in European open trials of fenofibrate and were better than the lipid changes seen at comparable times in the Lipid Research Clinics Coronary Primary Prevention Trial (LRC-CPPT) cholestyramine study.

Input-output analysis for total input rate and total traced mass of body cholesterol in man

The Stewart-Hamilton theorems for flow and volume are generalized to yield total input rate and total traced mass in multiple input, steady-state systems with partially labeled input. Application is made to existing decay curves of tracer cholesterol in human serum measured under a control steady state and again under a steady state of neomycin administration which lowered the serum cholesterol level. The effect of neomycin on the total traced mass of body cholesterol was to reduce it by 38, 40, 32, and 24 g, corresponding to 34, 40, 25, and 33%, in four patients studied. The present analysis utilizes only the area and the first time moment of the plasma decay curve. It is applicable to decay curves of more general shape than those that can be fitted by a small number of exponentials. The analysis does not require the assumption of compartments.

Receptor for AGEs (RAGE) blockade may exert its renoprotective effects in patients with diabetic nephropathy via induction of the angiotensin II type 2 (AT2) receptor

AIMS/HYPOTHESIS

The receptor for AGEs (RAGE) contributes to the development and progression of diabetic nephropathy. In this study, we examined whether the protective effects of RAGE blockade are exerted via modulation of the renal angiotensin II type 2 (AT2) receptor.

METHODS

Control and streptozotocin diabetic mice, wild-type or deficient in the AT2 receptor (At2 knockout [KO]) or RAGE (Rage KO), were studied for 24 weeks. Adenoviral overexpression of full-length Rage in primary rat mesangial cells was also used to determine the effects on AT2 production.

RESULTS

With diabetes, Rage-deficient mice had less albuminuria, and an attenuation of hyperfiltration and glomerulosclerosis as compared with diabetic wild-type and At2 KO mice. Renal gene and protein expression of RAGE was elevated with diabetes. Diabetic Rage KO mice had a greater increase in renal AT2 receptor protein than was seen in diabetic wild-type mice. Diabetes-induced increases in renal cytosolic and mitochondrial superoxide generation were prevented in diabetic Rage KO mice, but enhanced in all At2 KO mice. Adenoviral overexpression of RAGE or AGE treatment decreased cell surface AT2 expression, in association with increasing superoxide generation; both were reversed using antioxidants N-acetylcysteine and apocynin, and soluble RAGE in primary mesangial cells.

CONCLUSIONS/INTERPRETATION

RAGE appears to be a common and key modulator of AT2 receptor expression, a finding that would implicate a newly defined RAGE-AT2 axis in the development and progression of diabetic nephropathy.

Long-term decay of serum cholesterol radioactivity: body cholesterol metabolism in normals and in patients with hyperlipoproteinemia and atherosclerosis

After the intravenous injection of labeled cholesterol, the decay of specific radioactivity of total serum cholesterol was studied in 12 patients for 15-63 wk (average, 45 wk). In some, but not all of the patients studied, the slow slope of the decay curves suggested a deviation from monoexponential behavior, and the data of the slow period of the decay of specific activity were curve fitted by two exponentials. Six patients had serum lipid values regarded as normal and six had hyperlipoproteinemia. The data were analyzed by input-output analysis and yielded the following results. Values for the input rate of cholesterol (I(T)) (the sum of dietary and biosynthesized cholesterol) showed no difference between the normals and patients with hypercholesterolemia. The size of the rapidly miscible pool of cholesterol (M(a)) was significantly higher in the group of hypercholesterolemic patients partly due to increased serum cholesterol levels. The size of the total exchangeable body mass of cholesterol (M) was higher by an average of 49 g in the patients with hypercholesterolemia as compared to normals. The remaining exchangeable mass of cholesterol (M - M(a)) of the hypercholesterolemic subjects was higher by an average of 29 g as compared to normals. These differences were statistically significant.

Chylothorax: diagnosis by lipoprotein electrophoresis of serum and pleural fluid

This report describes a 31-year-old woman who underwent a technically difficult left pneumonectomy for tuberculosis and developed thereafter a large left pleural effusion which was milky in colour. A traumatic chylothorax was suspected, and the diagnosis was confirmed by simultaneous fasting pleural and serum lipid studies and lipoprotein electrophoresis. The latter study was especially helpful in confirming the chylous nature of the fluid in that it revealed a marked chylomicron band at the origin; this was not present in the patient's serum nor in the pleural fluid of five patients with other disease states studied as controls.

Review: the development of family quality of life concepts and measures

Historically, intervention programmes in intellectual and developmental disabilities have targeted the individual's special needs independent of the family and environmental context. This trend has been changing over the past two decades. This paper presents a literature review on changing trends in family support and the development of family quality of life (FQOL) and intellectual disability from a construct to a theory. The evolution of research in quality of life from the perspective of the individual with the disability to the family is described. A description of the development of FQOL measures is included, specifically an introduction and comparison of the two leading comprehensive initiatives on measuring FQOL - international FQOL project and the FQOL initiative of the Beach Center on Disability, in the USA. This paper provides the conceptual background and context to the other papers presented in this special issue, which focus on FQOL measurement in specific contexts.

Effect of neomycin on exchangeable pools of cholesterol in the steady state

Five patients received cholesterol-7alpha-(3)H intravenously during control periods. Specific activity of total serum cholesterol was determined serially during the 1st wk and weekly thereafter. 28-59 wk after the injection of the tracer, when no further radioactivity could be detected in serum cholesterol, 2 g of oral neomycin was given daily to four patients for the remainder of the experiment. Average total serum cholesterol concentrations were reduced by 20, 21, 26, and 29%, respectively, in these subjects. The fifth patient, given placebo, had no change in serum cholesterol. After a period of 12-26 wk of medication the intravenous injection of cholesterol-7alpha-(3)H was repeated, and while neomycin or placebo administration was continued, serum cholesterol specific activity was again determined serially during the 1st wk and weekly thereafter for 23-42 wk. The data were subjected to a two-compartment analysis. During the administration of neomycin, half-times of the cholesterol radio-activity decay curves were decreased in two patients and remained unchanged in two subjects. The size of the "intermediate" pool of cholesterol decreased in each patient during the administration of neomycin by 33, 36, 40, and 44%, respectively. The absolute decrease was much larger in each case than the concomitant reduction of serum cholesterol. There was no significant change in the data during the administration of placebo in one patient. The size of the "intermediate" pool can be calculated by compartmental analysis from the cholesterol decay curves. For the "slow" pool size and the other kinetic parameters only ranges of values can be deduced from the present experiment.

Long-term kinetics of serum and xanthoma cholesterol radioactivity in patients with hypercholesterolemia

In four patients with hypercholesterolemia (type II hyperlipoproteinemia) and xanthomatosis the decay of serum cholesterol specific activity was followed for 53-63 wk after pulse labeling. Specific activity of biopsied xanthoma cholesterol was measured four times in the course of the study. The xanthoma specific activity curve crossed and thereafter remained above the serum specific activity curve. The average ratio of xanthoma to serum specific activity was 4.7 at the end of the study. The final half-time of the xanthoma decay curves was significantly greater (average: 200 days) than the slowest half-time of serum specific activity decay (average: 93 days). The data were analyzed by input-output analysis and yielded the following results. The average value for the total input rate of body cholesterol (I(T)) (sum of dietary and biosynthesized cholesterol) was 1.29 g/day. The average size of the rapidly miscible pool of cholesterol (M(a)) was 55.7 g. and of the total exchangeable body mass of cholesterol (M) 116.5 g. The average value of M - M(a) (remaining exchangeable mass of cholesterol) was 60.8 g. The derived values for exchangeable masses of cholesterol, in the present patients with marked hypercholesterolemia, were significantly larger than in a group of patients with normal serum lipids in previous studies. One of the four patients died of a sudden acute myocardial infarction 53 wk after pulse labeling. Specific activity of aortic wall and atheroma cholesterol was 3.12 times that of serum. The ratio was close to 2 for adipose tissue and spleen, and was slightly above 1 or was close to unity in most other organs studied, with the exception of brain which showed a ratio of 0.19.

Effect of neomycin and other antibiotics on serum cholesterol levels and on 7alpha-dehydroxylation of bile acids by the fecal bacterial flora in man

Fresh feces from 25 patients were homogenized and incubated with labeled cholic or chenodeoxycholic acid. After 24 hours of incubation, the percent change to the 7α-dehydroxylated form was measured. In 11 patients, the oral administration of 2g of neomycin daily significantly reduced the levels of serum cholesterol (from an average of 316 mg/100 ml plasma to 237 mg/100 ml plasma) and markedly inhibited the extent of 7α-dehydroxylation of cholic acid (from 89% to 9%); in 2 patients whose serum cholesterol levels were not lowered, the degradation of cholic acid remained unchanged (control 93%, neomycin 91%). In 5 patients the administration of kanamycin reduced serum cholesterol levels (from 280 mg/100 ml plasma to 252 mg/100 ml plasma) and also inhibited 7α-dehydroxylation of cholic acid (from 92% to 21%); in 3 additional patients this drug failed to lower serum cholesterol concentrations and had no effect on bile acid degradation (control 91%, kanamycin 92%). Similar results were obtained with chloramphenicol in 3 patients, and equivocal results were obtained with chlortetracycline in 3 patients. The correlation coefficient between undegraded cholic acid and percent decrease in serum cholesterol concentrations ( r = 0.732) was statistically significant ( P < 0.001). It is proposed that serum cholesterol levels might be controlled in part by the prevalence of bile acid-degrading bacteria within the gastrointestinal tract.

Antiviral resistance mutations and genotype-associated amino acid substitutions in treatment-naïve hepatitis B virus-infected individuals from the Indian subcontinent

BACKGROUND/AIMS

Antiviral resistance is a major challenge to the treatment currently available for hepatitis B virus (HBV). In this study, mutations that may affect the antiviral efficacy in treatment-naïve HBV-infected individuals were analyzed.

METHODS

Ninety-seven treatment-naïve HBV-infected individuals were included in this study. HBV reverse transcriptase (rt) domains were sequenced and nucleotide differences were compared to GenBank wild-type sequences. Furthermore, HBV genotypes, subgenotypes and subtypes were determined by analyzing surface gene sequences.

RESULTS

An adefovir-related rtI233V mutation was identified in 4 subjects. The rtS213T lamivudine and entecavir refractory mutant was presented in 3 individuals. Altogether, drug-related, atypical and novel HBVrt amino acid substitutions were seen in 73 positions. The HBV genotypes A, C, D and G were depicted in 15, 21, 60 and 1 individuals, respectively. There were 17 HBVrt amino acid substitutions that are associated with certain genotypes of HBV. Mutations in HBVrt corresponded to established surface gene mutations in 9 patients.

CONCLUSION

This data shows that antiviral-resistant HBV strains do exist in treatment-naïve individuals in this region. Further studies are essential to characterize the role of HBVrt amino acid substitutions in response to anti-HBV therapy.

Infection rate in total hip arthroplasty as a function of air cleanliness and antibiotic prophylaxis. 10-year experience with 2,384 cementless Lord madreporic prostheses

To separate the respective effects of sterile air and antibiotic prophylaxis in orthopedic surgery, the authors reviewed 2,384 cementless total hip replacements performed from 1975 to 1984 for incidence of deep sepsis. During this period, a conventionally ventilated room (100 particle-forming units (pfu)/m3) and a laminar vertical flow (1 pfu/m3) were alternately used, without significant difference in the sepsis rate. Beginning in 1979, a prophylactic antibiotic regimen was added, which from 1979 to 1984 reduced the incidence of deep sepsis from 2.78% to 0.52%. There was also a change in common infecting organisms, from sensitive to resistant strains, which is not an insignificant consequence.

Reduction of serum cholesterol and triglyceride levels by the combined administration of neomycin and clofibrate

The combined oral administration of neomycin (2 g daily) and clofibrate (2 g daily) reduced significantly serum cholesterol levels in 15 of 16 patients. Most of these patients had type II hypercholesterolemia and clinical evidence of arteriosclerosis. The combined regimen of the two drugs was more effective in reducing cholesterol levels in about one third of the patients than administration of either one of these drugs alone. The average decrease of serum cholesterol in these patients while on the combined regimen was 38% from the control values. Control serum triglyceride levels were normal in most patients, thus the effect of the drugs on triglycerides was moderate. No noteworthy side effects were encountered. It is felt that a trial of treatment by the combined administration of neomycin and clofibrate is justified in patients with type II hypercholesterolemia and arterioscleroisis who are resistant to other forms of treatment or to treatment by a single drug.