Sib-pair analysis detects elevated Lp(a) levels and large variation of Lp(a) concentration in subjects with familial defective ApoB

Whether or not Lp(a) plasma levels are affected by the apoB R3500Q mutation, which causes Familial Defective apoB (FDB), is still a matter of debate. We have analyzed 300 family members of 13 unrelated Dutch index patients for the apoB mutation and the apolipoprotein(a) [apo(a)] genotype. Total cholesterol, LDL-cholesterol, and lipoprotein(a) [Lp(a)] concentrations were determined in 85 FDB heterozygotes and 106 non-FDB relatives. Mean LDL levels were significantly elevated in FDB subjects compared to non-FDB relatives (P < 0.001). Median Lp(a) levels were not different between FDB subjects and their non-FDB relatives. In contrast, sib-pair analysis demonstrated a significant effect of the FDB status on Lp(a) levels. In sib pairs identical by descent for apo(a) alleles but discordant for the FDB mutation (n = 11) each sib with FDB had a higher Lp(a) level than the corresponding non-FDB sib. Further, all possible sib pairs (n = 105) were grouped into three categories according to the absence/presence of the apoB R3500Q mutation in one or both subjects of a sib pair. The variability of differences in Lp(a) levels within the sib pairs increased with the number (0, 1, and 2) of FDB subjects present in the sib pair. This suggests that the FDB status increases Lp(a) level and variability, and that apoB may be a variability gene for Lp(a) levels in plasma.

Parenthood and lipid and lipoprotein levels in older men

PURPOSE

Parenthood for men and women has been associated with longevity, good physical health, and a deterrent effect on negative health behaviors which may affect subsequent mortality. However, decreased high density lipoprotein cholesterol (HDL-C) levels have been reported in women with greater numbers of pregnancies. Similar studies have not been reported in men. The present study examines the association of number of biological and nonbiological children with lipid and lipoprotein levels in men.

METHODS

Subjects included 1039 community-dwelling men aged 50-89 years. A standardized interview was used to obtain information on numbers of biological, adopted and stepchildren. Fasting total HDL, LDL cholesterol, and triglycerides were measured.

RESULTS

Men with five or more biological children were more obese than men without biological children. Alcohol consumption, cigarette smoking, and exercise did not vary in relation to the number of biological children. Only triglyceride levels were higher in men with four, five, or more children, and lower in men with one child as compared to men with no children, but this difference was no longer statistically significant after adjustment for obesity.

CONCLUSIONS

These results show no favorable effect of parenthood for men with regard to lifestyle, lipid, or lipoprotein levels. Increased triglyceride levels in men with more children appeared to be mediated by greater obesity in men with five or more biological children. These data also suggest that relations between parity and HDL-C levels found for women, could be associated with either the long term biologic consequences of pregnancy or the stress of childrearing.

Serum lipid profiles and the presence of yellow plaque in coronary lesions in vivo

Coronary angioscopy was used to examine the relation between plaque color and serum lipid levels in 44 patients with yellow plaque and 94 with white plaque. The findings indicate a strong relation between lipid profile and plaque color and therefore between lipid profile and plaque composition in vivo.

Low serum HDL-cholesterol is associated with raised tumor necrosis factor-alpha during ENL reactions

The concentrations of serum lipids and tumor necrosis factor (TNF) were measured in leprosy patients across the spectrum of the disease and in erythema nodosum leprosum (ENL) patients at the onset of the reaction and after the reaction had clinically subsided. Lepromatous/borderline lepromatous (LL/BL) patients had significantly higher serum triglyceride and lower HDL-cholesterol levels; there was no such change in the tuberculoid/borderline tuberculoid (TT/BT) patients. The household contacts (HC) of the LL/BL patients also had significantly lower serum HDL levels. ENL patients during the acute phase of the reaction had significantly lower total, LDL-, HDL-cholesterol levels compared to the stable LL/BL patients, and these changes were reversible to pre-ENL levels after the reaction had subsided. Serum TNF levels were significantly higher in household contacts and in LL/BL patients but were not statistically different in TT/BT patients. Serum TNF levels were also significantly higher during the acute phase of ENL, and declined after the clinical remission of the reaction to levels comparable with those of LL/BL patients. There was a significant negative correlation between serum TNF and HDL-cholesterol levels during and after ENL reaction. However, there was no such correlation between TNF and total or LDL-cholesterol levels in ENL patients. Our results suggest that the changes in HDL-cholesterol metabolism are a specific part of the host response to lepromatous leprosy and to the ENL reaction and may be mediated by increased TNF production.

Human low-density lipoproteins: oxidative modification and its relation to age, gender, menopausal status and cholesterol concentrations

Recently much evidence has accumulated indicating that oxidative modification of atherogenic lipoproteins plays an important role in atherogenesis. The goal of this study was to ascertain whether any association exists between this and the previously incriminated risk factors of atherosclerotic cardiovascular disease like age, gender and cholesterol concentration. Serum lipid profile, low-density lipoprotein (LDL) composition and indicators of LDL oxidation were examined in a cohort of healthy, predominantly middle aged men and women. LDL oxidation was assessed using the copper catalysis method, and monitored routinely by the increase in conjugated dienes over 4 to 24 hours. A more objective computer-aided technique was used to estimate the oxidative indices based on the sigmoidal fit to data. No marked differences between men and women were found with respect to mean age, total and LDL cholesterol, LDL protein and oxidation of LDL. The post-menopausal as compared to pre-menopausal status was associated with a greater extent of LDL oxidation, as well as with higher total serum cholesterol and its fractions, LDL cholesterol and LDL protein. No such differences were found in the data for men appropriately separated according to age. In a group with high risk LDL cholesterol, the total LDL oxidation was higher, as well as age and total cholesterol. Lag time and half-time of LDL oxidation were significantly shorter, while the oxidation rate of LDL was significantly faster when compared with data in the lower quartile. About six percent of participants had a considerably prolonged initial oxidation phase. These persons also showed low total and LDL cholesterol. High oxidation resistance was reversible and most probably caused by very low pre-existent oxidation products. Multiple regression analysis showed that the closest association among age, gender, lipid profiles and LDL oxidation indices existed between LDL cholesterol and conjugated diene production in both sexes (men: r = 0.93; women: r = 0.81). This association remained high even if adjusted for age. As in earlier epidemiological studies using logistic regression and showing age- and gender-related rising frequency of coronary heart disease, the present paper demonstrated age- and gender-related rising frequency of highly oxidized LDL. In both cases it was closely associated with an increasing LDL cholesterol concentration.

Triglyceride expression

Current epidemiologic reports claim an important role for triglycerides in coronary artery disease (CAD). By cross-sectional data analysis, the role of triglycerides was assessed in 1726 consecutive patients investigated for chest pain, 1119 with CAD and 607 with normal coronaries. Besides study of male and female patients as separate groups, the males were divided into age groups of below 40 years, 41 to 50 years, 51 to 60 years and over 61 years. The female patients were divided into those below 50 years and over 51 years because of smaller numbers. Using the mean value for cholesterol, triglyceride, HDL cholesterol, LDL cholesterol and body mass index for normals as the demarcation line, logistic regression analysis was carried out to study their association in the patients with CAD and normals. Results showed that while the odds ratio for total cholesterol were higher for the younger age groups, the odds ratio for triglycerides were consistently higher for the groups over 51 years both male and female. It is speculated that there may be a difference in the relative importance of lipid fractions with reference to age in the development of atherosclerotic plaque with cholesterol playing a more important role in younger people and triglycerides being equally or more important in older people, on the basis of metabolic handling of lipid fractions.

[Vitamin E distribution of lipoproteins in patients with coronary heart disease]

The oxidative modification of LDL could play an important role for the development of atherosclerosis. The present study was undertaken to compare the concentration of vitamin E in serum and lipoproteins between patients with coronary heart disease and a healthy control group. The study included 36 male patients with angiographically established coronary three-vessel disease and 32 healthy volunteers. Cholesterin, triglyceride, LDL-cholesterin, HDL-cholesterin, and vitamin E in serum and in lipoproteins were determined. The serum vitamin E concentration in the patients group was significantly higher than in controls. However, vitamin E was correlated with cholesterin in both groups. The distribution of vitamin E in healthy volunteers was LDL 53%, HDL 34% and VLDL 13%, whereas that in patients was LDL 57%, HDL 26% and VLDL 16%. The level of vitamin E in LDL was in the patient group significantly higher and correlated with the vitamin E- and the cholesterin-concentration in serum. The ratio vitamin E/cholesterin in LDL was in patients discretely lower, whereas the same ratio in HDL was higher. The results suggest that also in patients with coronary artery disease vitamin E is related to the lipid concentration. The decreased ratio vitamin E/cholesterin in LDL could be attributed to the oxidative modification of LDL.

Factors influencing Lp[a]- particle size as determined by gradient gel electrophoresis

This study examined factors influencing the particle diameter of Lp[a]-, the low density lipoprotein (LDL)-like moiety of Lp[a], in 26 subjects chosen to provide a range of Lp[a] and triglyceride levels. Lp[a] and LDL fractions were isolated by vertical density ultracentrifugation. Lp[a] was further purified using a lysine-Sepharose affinity column and Lp[a]- obtained by incubating Lp[a] with dithiothreitol. Lp[a], LDL, and Lp[a]- fractions were run on 3-13% gradient gels to determine particle diameter. Lp[a] size correlated positively with LDL size (r = 0.62; P < 0.001), but the association between Lp[a]- size and LDL size was stronger (r = 0.82; P < 0.0001). Log triglyceride level correlated inversely with Lp[a]- size (r = -0.72; P < 0.0001) and LDL size (r = 0.69; P < 0.0001). HDL cholesterol level correlated positively with Lp[a]- size (r = 0.67; P < 0.0005) and LDL size (r = 0.64; P < 0.0005). The strong correlation between LDL size and Lp[a]- size may be due to extracellular utilization of circulating LDL in the production of Lp[a] or may reflect the same metabolic processes influencing both these particles once Lp[a] has been formed.

The effect of simvastatin treatment on natural antioxidants in low-density lipoproteins and high-energy phosphates and ubiquinone in skeletal muscle

It has been hypothesized that treating hypercholesterolemic patients with statins will lead not only to a reduction in cholesterol, but also to inhibited synthesis of other compounds which derive from the synthetic pathway of cholesterol. In theory, this could further lead to ubiquinone deficiency in muscle cell mitochondria, disturbing normal cellular respiration and causing adverse effects such as rhabdomyolysis. Furthermore, ubiquinone is one of the lipophilic antioxidants in low-density lipoprotein (LDL), and therefore it has also been hypothesized that statin treatment will reduce the antioxidant capacity of LDL. We investigated the effect of 6 months of simvastatin treatment (20 mg/day) on skeletal muscle concentrations of high-energy phosphates and ubiquinone by performing biopsies in 19 hypercholesterolemic patients. Parallel assays were performed in untreated control subjects. The muscle high-energy phosphate and ubiquinone concentrations assayed after simvastatin treatment were similar to those observed at baseline and did not differ from the values obtained in control subjects at the beginning and end of follow-up. These results do not support the hypothesis of diminished isoprenoid synthesis or energy generation in muscle cells during simvastatin treatment. Furthermore, the results of analysis of antioxidant concentrations in LDL before and after simvastatin treatment indicate that the antioxidant capacity of LDL is maintained in simvastatin-treated patients.

An Iranian-Armenian LDLR frameshift mutation causing familial hypercholesterolemia

We used polymerase chain reaction single-strand conformation polymorphism (PCR-SSCP) analysis to detect a mutation in the low density lipoprotein receptor (LDLR) gene in a family of Iranian-Armenian origin. The mutation, designated FH Yrmeih, deletes two nucleotides from exon 10 of the LDLR gene, which causes a translational frameshift, whereby a truncated LDLR protein of the first 471 residues of the LDLR with an additional 41 abnormal residues and a premature stop codon would be created. The deletion was detected in a father and son with clinical features of heterozygous FH. To our knowledge this is the first pathogenetic LDLR mutation identified in FH patients of Iranian-Armenian ancestry.

Accurate direct determination of low-density lipoprotein cholesterol using an immunoseparation reagent and enzymatic cholesterol assay

Clinical laboratories currently estimate low-density lipoprotein cholesterol using the Friedewald formula, which requires fasting specimens and is subject to error with increasing triglyceride levels. We describe a rapid method for isolating low-density lipoproteins using the Direct LDL Immunoseparation Reagent for subsequent measurement of cholesterol by conventional assay. This method meets current guidelines for precision with within-run and run-to-run coefficients of variation of less than 3%. Results are in good agreement with the beta quantification reference method (Direct LDL-C = 1.03 [beta quantification] -0.06 mmol/L, [2.4 mg/dL] r = 0.980), there is minimal bias associated with increasing triglycerides or high-density lipoprotein cholesterol, and patient fasting is not required for accurate analysis. The Direct LDL Immunoseparation Reagent overcomes drawbacks of the Friedewald formula and appears to be suitable for accurate quantitation of low-density lipoprotein cholesterol in the routine laboratory.

Risk factors and atherosclerosis in youth autopsy findings of the Bogalusa Heart Study

The Collaborative Pathology Study is one of the most impressive programs of the Bogalusa Heart Study. Attempts are made to obtain complete and uniform necropsy coverage of all decreased young people who may have been examined in the Bogalusa Heart Study. Since 1978, autopsy specimens have been collected from 190 deaths, representing 65% of all known deaths in the study age category. The relation of antemortem risk factors for cardiovascular disease to early atherosclerotic lesions in the aorta and coronary arteries was assessed in those individuals previously examined in the Bogalusa Heart Study (N = 59). Aortic fatty streaks were strongly related to both total and low-density lipoprotein (LDL) cholesterol (r = 0.62, P < 0.0001 for each association), and were inversely correlated with the ratio of high-density lipoprotein (HDL) cholesterol to LDL plus very-low-density lipoprotein (VLDL) cholesterol (r = -0.29, P < 0.01). Coronary artery fatty streaks were associated with elevated total cholesterol, LDL cholesterol, VLDL cholesterol, and systolic blood pressure. Higher levels of LDL and VLDL cholesterol, triglycerides, systolic and diastolic blood pressure, and a lower ratio of HDL to LDL plus VLDL were found in those people with coronary artery fibrous plaques. Microscopy offered additional information about the characteristics of the aortic and coronary arterial intimal disease. Histologic observations have confirmed some of the relationships indicated with gross observations and show the complexity of this disease process. These findings emphasize the importance of an approach to preventive cardiology early in life.

[Detection of the Arg 3500-->Gln mutation of B apolipoprotein. Value in clinical practice]

OBJECTIVE

Familial defective apolipoprotein B-100, caused by a mutation in position 3500 of apolipoprotein B, induces hypercholesterolaemia, a major risk factor of coronary artery disease. The objective is to evaluate the interest of the detecting subjects bearing the Arg3500-->Gln mutation and to observe the response of these subjects to different physiological and therapeutic situations, in clinical practice.

METHODS

We performed a systematic screening among hypercholesterolaemic outpatients attending a lipid clinic. The heterozygote subjects were followed up during more than one year and, in some of them, we compared the efficiency of cholesterol-lowering drugs belonging to the different classes: fibrate and statine.

RESULTS

Two probands and 3 related subjects were detected. Three patients were treated. For two patients, reduction of LDL-cholesterol plasma levels was observed with both drugs but was significantly higher with statine than with fibrate. For the third one, carrying the E2E4 phenotype, the statine did not seemed to have a major effect.

CONCLUSION

The number of probands is in agreement with the frequency reported in literature. A possible interaction of the effect of statine with the apo E2 isoform is discussed.

Intracystic lipidic profile in fibrocystic breast disease

This study was designed to investigate the lipidic profile of fibrocystic breast disease. The study entailed measuring total cholesterol, high-density lipoprotein-cholesterol (HDL-C), low-density lipoprotein-cholesterol (LDL-C), very low-density lipoprotein-cholesterol (VLDL-C) and triglyceride levels in the serum of 50 women with fibrocystic breast disease without macrocysts, and in the serum and breast cyst fluid of 60 women with fibrocystic breast disease and macrocysts. The relationships between the lipids analyzed in the cyst fluid and intracystic estradiol, progesterone, dehydroepiandrosterone sulfate, testosterone and 17 alpha-hydroxyprogesterone were studied. No differences were found for serum lipid levels between the two groups of patients. The levels of total cholesterol and HDL-C were found to be significantly higher, and the levels of triglycerides and VLDL-C significantly lower in breast cyst fluid compared to serum. In cysts with high potassium concentrations, we found a higher concentration of cholesterol and HDL-C and a lower concentration of LDL-C than in cysts with a potassium/sodium ratio < 3. No significant differences were found in cystic levels of triglycerides and VLDL-C. Multiple regression analysis showed that the only intracystic variable, which was, in part, positively responsible for the hormone levels measured, was HDL-C. These data suggest that local steroidogenesis in fibrocystic breast disease uses HDL-C as the substrate.

The role of cholesterol accumulation in prosthetic vascular graft anastomotic intimal hyperplasia

PURPOSE

To demonstrate that modulation of plasma cholesterol concentrations affects prosthetic vascular graft anastomotic intimal hyperplasia (AIH), aortic grafts were examined histologically and biochemically in 41 rabbits.

METHODS

Twenty-seven rabbits were fed standard rabbit diet, whereas 14 were fed cholesterol-supplemented diet to induce hypercholesterolemia.

RESULTS

A smooth muscle cell proliferative response, similar to AIH in humans, was seen equally at the proximal and distal anastomoses. However, surface area and thickness of AIH were significantly greater in rabbits with hypercholesterolemia. Anastomotic tissue cholesterol concentrations were fifteenfold higher in rabbits with hypercholesterolemia than in rabbits with normal cholesterol concentrations and anastomotic cholesterol concentrations were fivefold higher than in the aorta away from the graft in rabbits with hypercholesterolemia. Preferential deposition of radioiodinated dilactitol tyramine coupled to low-density lipoproteins, but not albumin, was demonstrated in anastomotic areas and grafts of rabbits with normal cholesterol concentrations as well. Surface area and thickness of AIH correlated closely with plasma and tissue cholesterol concentrations.

CONCLUSIONS

Oxidized products of lipoproteins have been shown to stimulate production of growth factors that cause smooth muscle cell proliferation, migration, and synthetic function. It is likely they play an important part in prosthetic vascular graft AIH, similar to their role in atherogenesis.

Effect of Plantago ovata (psyllium) husk and seeds on sterol metabolism: studies in normal and ileostomy subjects

The diet of six normal and five ileostomy subjects was supplemented with 10 g/d Plantago ovata psyllium husk for 3 wk while six normal and four ileostomy subjects received 10 g/d psyllium seed. Fecal and ileostomy output, sterol excretion, serum cholesterol, and triglycerides were measured before and after supplementation. The husk had no effect on cholesterol or triglyceride concentrations in either normal or ileostomy subjects. Total and high-density-lipoprotein-cholesterol concentrations were reduced on average by 6.4% and 9.3%, respectively, in the normal group after seed supplementation. No effect on fecal bile acid excretion in the normal subjects was found after both regimes. Ileostomy bile acids were increased (on average 25%) after seed supplementation, whereas no effect on cholesterol concentrations was found. These results suggest that psyllium seed might be more effective than the husk in reducing serum cholesterol, that this cholesterol-lowering effect is not mediated by increased fecal bile acid losses, and increased ileal losses of bile acids might be compensated for by enhanced reabsorption in the colon.

Quantification of cholesterol in all lipoprotein classes by the VAP-II method

We have developed a high resolution microvolume Vertical Auto Profile (VAP) method for the simultaneous measurement of cholesterol in all lipoprotein classes, including lipoprotein[a] (Lp[a]) and intermediate density lipoprotein (IDL). This method, designated as VAP-II, uses a non-segmented continuous flow (controlled-dispersion flow) analyzer for the enzymatic analysis of cholesterol in lipoprotein classes separated by a short spin (47 min) single vertical ultracentrifugation. Cholesterol concentrations of high (HDL), low (LDL), very low (VLDL), and intermediate (IDL) density lipoproteins, as well as Lp[a], are determined by decomposing the spectrophotometric absorbance curve, obtained from the continuous analysis of the centrifuged sample, into its components using software developed in this laboratory. Analysis by VAP-II is rapid and sensitive (as little as 40 microliters plasma is required per assay). The resolution of lipoprotein peaks is considerably enhanced in the present analyzer compared to the previous analyzer (VAP-I, which used the Technicon AutoAnalyzer); improvement is especially noticeable for Lp[a] and IDL. Total and lipoprotein cholesterol values obtained by VAP-II correlated well with the values obtained by Northwest Lipid Research Laboratories (NWLRL). VAP-II Lp[a] cholesterol values also correlated well with the Lp[a] mass values obtained by an immunoassay technique performed at NWLRL (r = 0.907). The reproducibility and accuracy of the method are within the requirements of the CDC-NHLBI (Centers for Disease Control-National Heart, Lung, and Blood Institute) Lipid Standardization Program.

Risk factors predicting chronic rejection of renal allografts

Chronic rejection is clinically defined as a gradual but progressive impairment of renal allograft function in the absence of other specific causes. The risk factors predisposing to chronic rejection are incompletely known. In this prospective single-center project, logistic regression analysis was used to study the long-term outcome of 94 consecutive first renal allografts in relation to 10 potential risk factors. Whether serum lipid levels, histopathological changes or the mode of immunosuppressive therapy had a predictive value for chronic rejection was of special interest. The risk factors for renal allograft outcome were determined 2 years after the transplantation, when graft function was still normal, and the results were evaluated 2 years later. Occurrence of acute rejections, cold ischemia time, the high-density lipoprotein cholesterol level, and the high-density lipoprotein and total cholesterol ratio were not significant predictors of graft outcome. In a univariate analysis, triglyceride, total cholesterol, and low-density lipoprotein cholesterol level, and donor age were significantly related to graft outcome. In a logistic regression analysis, triple immunosuppressive therapy was better than any double-drug regimen in preventing the deterioration of renal allografts. Incipient histological changes in graft biopsy, quantitated as the "chronic allograft damage index," was the most important single predictor of chronic rejection. The effect of both the histological changes and low-density lipoprotein cholesterol on adverse graft outcome was level dependent.

The relationship between plasma and dialysate lipoproteins and apoproteins in patients treated by continuous ambulatory peritoneal dialysis

End-stage renal disease is frequently associated with lipoprotein abnormalities, manifested primarily by elevated very low-density lipoprotein levels combined with a decrease in high-density lipoprotein levels. These lipoprotein disturbances are further exacerbated in continuous ambulatory peritoneal dialysis. We examined the lipoprotein and apolipoprotein profiles in the blood and dialysate effluents of eight normolipidemic and five hypertriglyceridemic patients with end-stage renal failure treated with continuous ambulatory peritoneal dialysis. The normolipidemic patients were found to have significantly greater losses, as expressed by the fractional catabolic rates through the dialysate, for protein, total cholesterol, and very low-density lipoprotein cholesterol. These results suggest that the hypertriglyceridemia associated with continuous ambulatory peritoneal dialysis may be mitigated in some patients by the excessive loss of very low-density lipoprotein, or some other plasma constituent, into the dialysate effluent.

Levels of insulin and cholesterol in human follicular fluid

OBJECTIVE

The intent of this study was to ascertain if there was a correlation between insulin and cholesterol levels in follicular fluid and oocyte fertilizability and developmental potential.

MATERIALS AND METHODS

The levels of immunoreactive cholesterol, total cholesterol, high-density lipoprotein-cholesterol, very-low-density lipoprotein-cholesterol were determined in follicular lipoprotein-cholesterol were determined in follicular fluid samples obtained during transabdominal-transvesicular aspiration of follicles under ultrasound guidance, from patients treated with clomiphene citrate and human menopausal gonadotropin for in vitro fertilization. Insulin was measured by radioimmunoassay and cholesterol by an enzymatic method.

RESULTS

Follicles containing oocytes with better fertilizability and greater developmental potential possessed lower concentrations of immunoreactive insulin and high-density lipoprotein-cholesterol, and higher concentrations of low-density lipoprotein- and very-low-density lipoprotein-cholesterol.

CONCLUSION

These lipoprotein- and very-low-density lipoprotein-cholesterol.

CONCLUSION

These changes in the level of cholesterol carried by the various lipoproteins in the follicular fluid strongly suggest that oocyte maturation is influenced by insulin-dependent steroidogenesis.

Evaluation of liver function and lipid metabolism following Norplant implant removal

A final evaluation of this longitudinal study involving 100 Singaporean women shows that, besides a significantly elevated bilirubin level, there is no other evidence of hepatocellular dysfunction with the use of Norplant implants. The elevated bilirubin levels remained significantly elevated six months after removal of the implant. Despite this, all values of bilirubin remained within the clinical range for the population studies. As regards lipid metabolism, total cholesterol, LDL-cholesterol and total triglycerides continued to remain below the pre-insertion mean at six months post-removal. The HDL-cholesterol showed a significant increase following removal of the implants. As a result, the HDL-cholesterol/(total cholesterol-HDL-cholesterol) ratio continued to remain above 0.200. This indicates that Norplant implants are not directly contributory to cardiovascular risk.

Role of triglycerides in coronary artery disease: lessons from the Prospective Cardiovascular Münster Study

The incidence of atherosclerotic coronary artery disease (CAD) was assessed in 4,576 male participants of the Prospective Cardiovascular Münster (PROCAM) study, aged 40-64 years, over a 4-year follow-up period. In this time, 122 study participants developed atherosclerotic CAD (89 definite nonfatal myocardial infarctions and 33 definite atherosclerotic CAD deaths). Univariate analysis revealed a significant association between the incidence of atherosclerotic CAD, and high-density lipoprotein (HDL) cholesterol (p < 0.001) and triglyceride (p < 0.01) levels. The relation to HDL cholesterol remained after adjustment for other risk factors. By contrast, the relation between the incidence of atherosclerotic CAD and triglycerides disappeared if, in a multivariate analysis by means of a multiple logistic function, cholesterol or HDL cholesterol was taken into account. However, the data suggested that hypertriglyceridemia is a powerful additional coronary risk factor, when excessive triglycerides coincide with a high ratio (> 5.0) of plasma low-density lipoprotein (LDL) cholesterol to HDL cholesterol. Even though the prevalence of this subgroup was only 3.7%, it included a quarter of all atherosclerotic CAD events observed.

Diagnosis of heterozygous familial hypercholesterolemia. DNA analysis complements clinical examination and analysis of serum lipid levels

The concordance of clinical and molecular genetic diagnoses of heterozygous familial hypercholesterolemia (FH) was studied in 65 subjects (10 propositi and 55 first-degree relatives) from 10 families with FH. Nine propositi were carriers of the FH-Helsinki deletion of the low density lipoprotein (LDL) receptor gene, prevalent in the Finnish population, while a new deletion, extending from intron 14 to intron 15 of the LDL receptor gene, was identified in one family. Serum LDL cholesterol levels used in the clinical diagnosis (less than 5.0 mmol/l, not FH; 5.0-5.9 mmol/l, possible FH; greater than or equal to 6.0 mmol/l, FH; limits are 1 mmol/l lower for those less than 18 years) were derived from an authoritative recommendation. Tendon xanthomas constituted an additional criterion. With the DNA analysis as the reference, 55 (85%) subjects could be correctly classified clinically as FH patients or subjects without FH. The remaining 10 subjects were misclassified or were in the "possible FH" category. When the age- and sex-specific 95th percentile LDL cholesterol levels were used instead of the rigid values for both adults and children, the percentage of correct diagnoses rose to 95%. Common genetic polymorphisms of apolipoproteins E and B did not markedly affect LDL cholesterol levels in FH patients, whereas increasing age and obesity were associated with elevated LDL levels. In conclusion, DNA analysis is a valuable adjunct to the diagnosis of FH that is applicable to families with a known mutation of the LDL receptor gene. If DNA methods are not available, age- and sex-specific LDL levels should be used as an aid in the clinical diagnosis of FH.

Contribution of a risk factor clinic to lipid management in patients with coronary artery disease

The progress of a cohort of 145 patients seen between June 1986 and June 1989 was reviewed. These patients had treatment prescribed by the clinic and had data recorded over serial visits; they allowed us to determine the contribution of the risk factor clinic. Eighty-six percent had coronary artery disease. Patients were given nutritional advice, partly in groups. In addition 61% were treated with drug therapy. Seventy-four percent had modified their diet before the clinic visit but only 32% received less than 30% of energy from fat; the number rose to 67% by discharge. Sixty-four percent had a body mass index of 25 or greater, falling to 53% at discharge. Mean total cholesterol of the 145 patients was 7.9, HDL cholesterol 1.06, and total:HDL cholesterol ratio 7.7 mmol/L. Changes with clinic management were: total cholesterol -19%, HDL cholesterol +11%, total:HDL cholesterol ratio -25%, LDL cholesterol -21%. Despite these changes, levels were less than optimal for patients with coronary arterial disease in at least 50% of patients at the time of discharge. Improved results can be achieved only with a more aggressive approach to drug therapy. Recent studies in patients with coronary disease provide strong support for such a change in management.

Interaction between dietary proteins and lipids in the regulation of serum and liver lipids in the rabbit. Effect of fish protein

Purified diets varying in dietary protein, namely casein (CA), soy protein (SP), fish protein (FP), and lipid origin (corn oil (CN), coconut oil (CO)) were fed to rabbits to evaluate the effects of protein and fat source, as well as protein-lipid interactions, on serum total, lipoprotein and hepatic lipid levels. Dietary proteins and lipids exerted a separate effect on serum total cholesterol (C), very low-density lipoprotein cholesterol (VLDL-C), and low-density lipoprotein cholesterol to high density lipoprotein cholesterol (LDL-C/HDL-C) ratio. Hence, CA increased serum cholesterol compared to SP, while coconut oil enhanced serum and VLDL-C, and decreased LDL-C/HDL-C compared to corn oil. Dietary proteins interacted with dietary lipids to modulate HDL-C levels. Thus, FP maintained a high level of HDL-C regardless of lipid origin, compared to CA and SP whose HDL-C levels were decreased by corn oil, compared to coconut oil. A dietary protein-lipid interaction was also observed in the regulation of liver cholesterol levels. Coconut oil, compared to corn oil, decreased liver cholesterol in rabbits fed FP, whereas hepatic cholesterol concentration was unaltered by dietary lipid source in CA- and SP-fed rabbits. These results demonstrate that dietary proteins act synergistically with dietary lipids to regulate cholesterol metabolism in the rabbit.

Alterations in some lipid components and Ca2+ ATPase activity in brain of rats fed an atherogenic diet

Male Wistar rats were fed an atherogenic diet for four months to investigate possible diet-induced lipid alterations and brain Ca2+ ATPase activity. Total cholesterol and triglyceride levels were found to be increased significantly in both serum and brain while the phospholipid level was decreased in both. The distribution of serum cholesterol between high-density and low-density lipoproteins was altered when compared to control rats with a decrement in HDL-cholesterol and a pronounced increment in LDL-cholesterol. The atherogenic diet resulted in about 50% depression in brain Ca2+ ATPase activity. It is concluded that alterations in ion transport and neurotransmitter release may be expected due to pronounced inhibition of brain Ca2+ ATPase activity in rats fed an atherogenic diet.

Oral contraceptives and lipids and lipoproteins: Part I--Variations in mean levels by oral contraceptive type

A randomized clinical trial of oral contraceptives evaluated 67 women on 50 micrograms ethinyl estradiol (EE) and 1.0 mg norethindrone (NE), 61 women on 35 micrograms EE and 1.0 mg NE, and 64 women on 35 micrograms EE and 0.5 mg NE. Fasting lipids and lipoproteins were measured at baseline, three, six and nine months. All groups showed an increase in plasma total cholesterol, triglycerides, low-density lipoprotein/apolipoprotein B and apolipoprotein A-1. The group taking the preparation with 0.5 mg of NE was the only one to result in an elevation of high-density lipoprotein cholesterol; the other two groups showed declines in the mean levels of this lipoprotein over the study time period. Mean changes in lipid/lipoprotein levels associated with oral contraceptive use appear to be at least partially related to the doses of the contraceptive steroids.

Dyslipoproteinemia in murine systemic lupus erythematosus

Dyslipoproteinemia, a feature of systemic lupus erythematosus may contribute to premature atherosclerosis. In order to develop an experimental model for this dyslipoproteinemia we measured plasma concentrations of lipoproteins in juvenile NZB/W (lupus) and NZB/B (control) mice. Additionally to evaluate the effects of a diet rich in n - 3 fatty acids we measured lipoprotein concentrations in mice on normal or menhaden oil-enriched diets. The lupus mice had elevated triglycerides compared to the controls, similar to that seen in human SLE patients (161 +/- 31 vs 113 +/- 13 mg/dl, P less than 0.003). In contrast, the menhaden oil diet fed NZB/W mice had triglycerides similar to the NZB/B control fed group. In the NZB/W murine SLE model, dyslipoproteinemia is an early sign of disease as has been shown in man, therefore this model will be useful in elucidating the mechanism of dyslipoproteinemia in SLE.

Effect of yogurt intake on plasma lipid and lipoprotein levels in normolipidemic males

To determine the effect of yogurt intake on plasma lipid and lipoprotein levels, studies were carried out in 18 normolipidemic males during 3 dietary phases. Phase 1 was a low-fat, low-cholesterol baseline diet consumed for 3 weeks. The baseline diet was supplemented with low-fat yogurt (16 oz/day) for 4 weeks during phase 2, and during phase 3 the supplement consisted of a non-fermented dairy product (16 oz low-fat milk plus 10% milk solids). Average body weights and dietary intakes of fat, cholesterol and polyunsaturate/saturate fat ratios were not significantly different for the 3 dietary phases. Plasma total, LDL- and HDL-cholesterol were unaffected by either the yogurt of low-fat milk concentrate. The results indicate that yogurt, as an example of a fermented dairy product, has no effect on plasma cholesterol levels of normolipidemic males.

Insolubilization of low density lipoprotein induces cholesterol accumulation in cultured subendothelial cells of human aorta

Primary cultures of typical and modified smooth muscle cells isolated from the intima of human aorta were used to study the mechanism whereby low density lipoprotein (LDL) induces accumulation of intracellular cholesterol. Incubation of intimal cells with native LDL obtained from human plasma did not lead to deposition of total cholesterol. LDL added to the cultures simultaneously with hyaluronic acid, heparin, chondroitin sulfate, fibronectin, and mouse monoclonal antibody against LDL also failed to alter the cellular cholesterol. On the other hand, 24-h incubation of the cells with LDL in the presence of dextran sulfate, gelatin, particles of aortic elastin, particles of collagenase-resistant aortic matrix, goat polyclonal antibodies against LDL or latex beads caused a significant (1.5-7-fold) increase in total cholesterol. The compounds which stimulated cholesterol deposition are able to form precipitating complexes with LDL. On the contrary, the agents which failed to induce cholesterol accumulation were unable to insolubilize LDL. A direct correlation (r = 0.927) was found between the cholesterol content of the insoluble complex and the increment of cholesterol in the cultured cells. To find out whether LDL plays a specific role in the deposition of intracellular cholesterol, very low density lipoproteins and high density lipoproteins were used. These lipoproteins stimulated the accumulation of intracellular cholesterol in the presence of agents capable of forming insoluble associates with them. Our data suggest that insolubilization of lipoproteins is a key event in the LDL-mediated accumulation of intracellular cholesterol induced by various agents.

Treating hyperlipidemia, Part I: Whether and when in the elderly

There are elderly persons at increased risk of coronary heart disease due to elevated LDL cholesterol, lowered HDL cholesterol, or both. Risk difference data seem to indicate that the reduction in risk of coronary artery disease by lowering elevated cholesterol values is the same in the elderly as it is in younger persons. hence we recommend screening for total cholesterol in the elderly, followed by a fasting lipid profile in those with screening cholesterol values over 200 mg/dl (230 mg/dl by certain methods). Comparative LDL and HDL cholesterol values, as well as L/H ratios, are presented for assisting in assessment of results and for planning therapeutic strategy.

A 31-year-old woman with homozygous familial hypercholesterolemia without significant lesions in the coronary arteries

Cardiovascular complications were examined in a 31-year-old woman with homozygous familial hypercholesterolemia (FH) (LDL receptor defective type), who had had no clinical symptoms of coronary artery disease. She had delivered 2 children without any cardiac complications, and her exercise electrocardiogram showed no positive findings for ischemic heart disease. Coronary angiography showed no significant arterial lesions, and left ventriculography revealed good contraction of the left ventricle (ejection fraction: 67%). This is considered to be a very rare case of homozygous FH without significant lesions in the coronary arteries. This might be attributed at least in part to her dietary regimen consisting of a very low fat and low calorie diet, to the residual LDL receptor activity or to the low value of prothrombin time.

Predictive value of the exercise tolerance test for mortality in North American men: the Lipid Research Clinics Mortality Follow-up Study

More than 3600 white men, from 30 to 79 years old and without a history of myocardial infarction, underwent submaximal treadmill exercise tolerance tests as part of their baseline evaluation for the Lipid Research Clinics Mortality Follow-up Study. The exercise test was conducted according to a common protocol and coded centrally; depression of the ST segment by at least 1 mm (visual coding) and/or 10 microV-sec (ST integral, computer coding) signified a positive test. Concurrent measurements of age, blood pressure, history of cigarette smoking, and plasma levels of lipids, lipoproteins, and glucose, as well as other coronary risk factors, were obtained. Cumulative mortality from cardiovascular disease was 11.9% (22/185) over 8.1 years mean follow-up among men with a positive exercise test vs 1.2% (36/2993) over 8.6 years mean follow-up among men with a negative test. Three-quarters (43) of these deaths were due to coronary heart disease. The relative risk for cardiovascular mortality associated with a positive exercise test was 9.3 before and 4.6 after age adjustment. Cardiovascular mortality rates were especially elevated (relative risk 15.6 before and 5.1 after age adjustment) among the 82 men whose exercise tests were adjusted "strongly" positive based on degree and timing of the ischemic electrocardiographic response. A positive exercise test was also moderately associated with noncardiovascular mortality; the relative risk for all-cause mortality was 7.2 before and 3.4 after age adjustment. The relative risk for cardiovascular mortality associated with a positive exercise test was not appreciably altered by covariance adjustment for known coronary risk factors other than age. A positive exercise test was a stronger predictor of cardiovascular death than were high plasma levels of low-density lipoprotein cholesterol, low plasma levels of high-density lipoprotein cholesterol, smoking, hyperglycemia, or hypertension. Its impact on risk of cardiovascular death was equivalent to that of a 17.4 year increment in age.

Quantification of LDL cholesteryl ester contribution to biliary steroids in the rat

The proportion of LDL cholesteryl ester converted to biliary steroids was quantified in the rat. The pre-existing pool of bile was allowed to drain for 10-12 h through a bile duct cannula. A single intravenous pulse injection of LDL labelled with [3H]cholesterol linoleyl ester was made, followed by a constant infusion of the same material in order to maintain constant specific radioactivity in plasma. A new steady state was achieved within 6 h and bile samples were then collected hourly until 12 h. Although substantial amounts (53-61 micrograms/h) of cholesteryl ester were released into the liver during LDL catabolism, only a very small fraction (0.8-1.90 micrograms/h) was found in biliary steroids. The proportion of LDL cholesteryl esters contributing to biliary steroids was only 1-2%. These results perhaps explain why perturbations to accelerate bile acid excretion have no effect on plasma LDL cholesterol concentration in the rat.

Nonprogression of coronary artery atherosclerosis in homozygous familial hypercholesterolemia after 31 months of repetitive plasma exchange

The effects of plasma exchange performed every two weeks for 31 months in combination with diet and drug therapy were studied in a patient with receptor-defective homozygous familial hypercholesterolemia. Coronary angiography performed three years prior to commencing plasma exchange was compared to angiography 31 months after starting the program. Comparison of the angiograms taken six years apart showed no progression of coronary atheroma in the main left coronary artery in which a 30% narrowing was originally seen. An internal mammary artery-coronary artery bypass remained widely patent and showed no development of atherosclerosis. Plasma cholesterol levels were reduced 46% by plasma exchange, diet and drug compared to diet and drug alone. Achilles tendon xanthoma diminished significantly. It appears that plasma exchange combined with diet and drug therapy, while not producing regression of existing atheromatous lesions, does retard or prevent further progression.

Modulation of apolipoprotein B antigenic determinants in human low density lipoprotein subclasses

To investigate the effect of low density lipoprotein (LDL) heterogeneity on the conformation of LDL apolipoprotein B (apo-B), the immunoreactivities of 6 monoclonal antibodies against LDL apo-B were measured in 3 LDL subfractions isolated by equilibrium density gradient ultracentrifugation. To ensure a broad range of LDL particles, the LDL subfractions were prepared from normal subjects and patients with hyperapobetalipoproteinemia. With 3 of the antibodies, 1D1, 5E11, and 3A10, LDL fractions 1 (the most buoyant), 2 (the intermediate), and 3 (the densest) were equally immunoreactive and competed similarly with reference whole LDL. In contrast, with 3 other antibodies, 2D8, 3F5, and 4G3, fraction 1 was significantly more reactive than fraction 3; that is for each in turn, 290, 250, and 150% more of the densest LDL protein was required to achieve the same displacement as with fraction 1. Further, the immunoreactivities of the 3 LDL fractions with antibodies 2D8, 3F5, and 4G3 were negatively correlated with their LDL cholesterol to LDL protein ratio with r values of 0.727, 0.898, and 0.870, respectively, suggesting that as LDL particle size decreases, the conformation of the LDL apo-B changes progressively. It is of interest that the antigenic determinants recognized by 3F5 and 4G3 are close to the LDL receptor recognition site on LDL apo-B. Therefore, it is possible that the reduced immunoreactivity of these determinants in dense LDL may be the in vitro correlate of the reduced fractional catabolics rate of dense LDL compared to buoyant LDL previously observed in vivo.

The distribution of cholesterol and apoprotein A-I between the lipoproteins in plasma and peripheral lymph from normal human subjects

The lipoproteins of peripheral lymph and plasma from normal human subjects were separated according to their density by sequential ultracentrifugation and according to their size by gradient gel electrophoresis and gel exclusion chromatography. High density lipoproteins (HDL) carried a higher proportion of the total cholesterol in lymph than in plasma. Within the HDL fraction, the less dense and more lipid-rich component (HDL2) carried a higher proportion of the total HDL cholesterol in lymph than in plasma. Gradient gel electrophoresis showed (1) a higher proportion of large to small HDL particles in lymph than in plasma and (2) the presence of at least three populations of apo A-I-containing lipoproteins with Stokes diameters larger than the Stokes diameter of HDL2. Separation by gel exclusion chromatography showed that the proportion of large HDL particles with a high cholester: apo A-I ratio was greater in lymph than in plasma. In view of the sieving effect of the blood capillaries, which favours the passage across the capillary walls of smaller vs larger particles, we suggest that the higher ratio of large to small HDL particles in lymph than in plasma is due to the conversion of small to large HDL in the interstitial fluid by incorporation of cholesterol and other lipids from extravascular cells into the smaller particles.