Risk factors for ischaemic heart-disease in normal men aged 40. Edinburgh-Stockholm Study

Lipid lowering and ischaemic heart disease

There is a non-linear discontinuous relationship between serum cholesterol, and LDL cholesterol, with IHD. There is no sound evidence that reduction of serum cholesterol below 200-210 mg/dl will reduce IHD incidence. It has not yet been shown that regression of advanced lesions in middle-aged men can occur, but regression of cholesterol-induced atheromatous lesions has been achieved in juvenile monkeys by discontinuing atherogenic diets. While the three major primary prevention trials of lowering raised serum cholesterol were all associated with reduction in the non-fatal mortality from IHD--thereby supporting the lipid hypothesis--all also showed an increase in non-cardiovascular mortality. It is legitimate to raise doubts about the consequences on normal biological function of ageing cells of reducing cholesterol concentrations over many years. It is probably of little value to reduce raised serum cholesterol concentrations in patients with overt IHD, since their prognosis is largely determined by the extent of myocardial damage sustained and of coexisting thrombogenic tendency. Patients with familial hypercholesterolaemia should be vigorously treated with a diet with a P/S ratio 1-5, cholestyramine and perhaps nicotinic acid also. The general population should be advised to reduce fat calories to below 30 per cent of total energy with no more than one-third from saturated fat.

Fatty acid composition of serum and adipose tissue lipids in males with chronic renal failure. Relations to serum lipoproteins and clinical factors

We have analysed the fatty acid composition of serum cholesterol esters (CE), phospholipids (PL) and triglycerides (TG) and of adipose tissue (AT) lipids in 72 males and chronic renal failure (CRF). Sixteen patients were treated with protein-poor diet. 16 with hemodialysis. The results have been related to clinical aspects of the disease and to abnormalities in serum lipid and lipoprotein concentrations. The major findings were high relative content of oleic acid and a low relative content of linoleic acid in all lipids in the diet-treated group compared to both controls and to the untreated and dialysed patients. Tendencies in the same directions were seen also in the untreated subjects, significant for oleic and linoleic acid in CE and for oleic acid in PL. These changes did not correlate to serum of lipoprotein lipids, or to serum creatinine concentrations in patients not on diet or dialysis, indicating that other factors are more important in modifying the fatty acid metabolism in CRF. The composition of the protein-poor diet, which was rich in fat but low in linoleic acid in relation to oleic acid, is probably a major factor explaining our findings in the diet-treated group. Since low levels of linoleic acid in plasma and AT lipids have been suggested to be a risk factor for atherosclerosis, more attention should be paid to the content and composition of dietary fat in order to prevent the occurrence of such low levels.

Serum apolipoproteins, lipoproteins and fatty acids in relation to ischaemic heart disease in northern and southern European males

Serum apolipoprotein and lipoprotein concentrations, fatty acid spectra of various lipids, dietary habits and common risk factors for ischaemic heart disease were studied in 73 and 77 randomly selected, 50-year-old healthy men in Naples and Stockholm, respectively. Mean serum cholesterol concentration was higher in Stockholm than in Naples men (6.23 vs. 5.47 mmol/l, p less than 0.001) as were low (LDL) (4.08 vs. 3.57 mmol/l, p less than 0.001) and high (HDL) (1.40 vs. 1.25 mmol/l, p less than 0.001) density lipoprotein fractions. Mean serum triglyceride concentrations did not differ. Mean apolipoprotein B and C-I concentrations were higher in Stockholm men (1,116 vs. 1,020 mg/l, p less than 0.05 and 96 vs. 79 mg/l, p less than 0.01, respectively). Stockholm men derived significantly more of their calories from fat (38 vs. 28%, p less than 0.001) and the dietary fat had significantly lower polyunsaturated-to-saturated fatty acid ratio (P/S-ratio 0.29 vs. 0.51, p less than 0.001), and less from carbohydrate (44 vs. 49%, p less than 0.001) than Naples men, respectively. Mean caloric intake and mean weight/height index did not differ. Stockholm men had higher blood pressures, but there were more smokers among Naples men. The higher fat intake in Stockholm men may offer an explanation of the differences seen in lipoprotein and apoprotein concentrations and compositions but other factors, such as genetic influences cannot be excluded. A greater cholesterol flux through the plasma compartment in Stockholm men may be one important factor contributing to the higher incidence of ischaemic heart disease in this population.

Role of controlled trials in evaluating preventive medicine procedures

A number of large controlled trials evaluating methods of preventing cardiovascular disease are reviewed, mainly for their methodological lessons. They include trials of treatment for hypertension (Veterans Administration, Australian, and the Hypertension Detection and Follow-up Program); of coronary heart disease prevention by drugs (post-infarction beta-blockers, the WHO trial of clofibrate, and the Lipid Research Clinics Program); and of health education (the Multiple Risk Factor Intervention Trial and the WHO European Multifactorial Trial). Although important evidence has emerged, expectations from large trials of this kind are now more sober. Their findings have to be considered alongside the rest of the evidence, and preventive policy can only be based on a best judgment. Any hope of 'proof' is naive.

Replacement of butter on bread by rapeseed oil and rapeseed oil-containing margarine: effects on plasma fatty acid composition and serum cholesterol

The effects of zero-erucic acid rapeseed oil and rapeseed oil-containing margarine on plasma fatty acid composition and serum cholesterol were studied in butter users (n43). Compliance to the substitution was followed by fatty acid analysis of total plasma and plasma phospholipids. The amount of substitute fats represented, on average, 21% of total fat and 8% of total energy intake. Changes in the relative fatty acid composition of plasma phospholipids indicated further fatty acid metabolism, and were closely related to the serum cholesterol level. The reduction in saturated fatty acids led to a significant increase in the proportion ofn-3 andn-6 polyunsaturated fatty acids (PUFA) with the rapeseed oil diet, whereas the margarine caused a significant rise inn-6 PUFA only. The increase in the proportions of the two PUFA families occurred in accordance with their competitive order, most completely with the rapeseed oil diet. When butter was replaced by rapeseed oil, low-density-lipoprotein-cholesterol decreased by an average of 9.1% without a reduction in high-density-lipoprotein-cholesterol. During margarine substitution the reduction was 5.2%, on average. Of the plasma phospholipids, α-linolenic acid and the linoleic:stearic acid ratio, but not oleic acid, were the components most significantly correlated with serum cholesterol levels or the decrease in these levels. The results show that rapeseed oil can act primarily as a source of essential fatty acids, rather than that of monoenes, in the diet of butter users.

Prevalence of the metabolic syndrome across cardiorespiratory fitness levels in women

OBJECTIVE

To determine the prevalence of the metabolic syndrome across age strata and cardiorespiratory fitness (CRF) levels in women.

RESEARCH METHODS AND PROCEDURES

7104 women underwent a physical examination, including a maximal treadmill exercise test. Participants were divided into CRF quintiles according to age. The metabolic syndrome was identified using Adult Treatment Panel-III Guidelines. Tests for trend were performed on demographic variables across CRF quintiles, as well as prevalence of the metabolic syndrome across CRF quintiles, age strata, and maximal workload achieved [maximal metabolic equivalent (MET) level].

RESULTS

The overall prevalence of the metabolic syndrome was 6.5%. Age- and smoking-adjusted prevalence was lower across quintiles of CRF (19.0%, 6.7%, 6.0%, 3.6%, and 2.3% for quintiles I to V, respectively, p for trend = 0.001). Smoking-adjusted prevalence of the metabolic syndrome was higher across age strata (2.4%, 2.7%, 6.4%, 8.7%, 15.3%, and 16.1% for ages 20 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69, and 70 to 80, respectively, p for trend = 0.001). Prevalence of the metabolic syndrome in the different age groups for women who achieved a maximal MET level of 11 or higher was one-third to one-fourth that of women who achieved lower maximal MET levels.

DISCUSSION

Prevalence of the metabolic syndrome was markedly lower across progressively higher levels of CRF in women of different age strata. Because regular physical activity improves components of the metabolic syndrome, modest increases in CRF among low fit women may ameliorate the metabolic syndrome in some instances.

ACAT2 is localized to hepatocytes and is the major cholesterol-esterifying enzyme in human liver

BACKGROUND

Two acyl-coenzyme A:cholesterol acyltransferase (ACAT) genes, ACAT1 and ACAT2, have been identified that encode 2 proteins responsible for intracellular cholesterol esterification.

METHODS AND RESULTS

In this study, immunohistology was used to establish their cellular localization in human liver biopsies. ACAT2 protein expression was confined to hepatocytes, whereas ACAT1 protein was found in Kupffer cells only. Studies with a highly specific ACAT2 inhibitor, pyripyropene A, in microsomal activity assays demonstrated that ACAT2 activity was highly variable among individual human liver samples, whereas ACAT1 activity was more similar in all specimens. ACAT2 provided the major cholesterol-esterifying activity in 3 of 4 human liver samples examined.

CONCLUSIONS

The data suggest that in diseases in which dysregulation of cholesterol metabolism occurs, such as hypercholesterolemia and atherosclerosis, ACAT2 should be considered a target for prevention and treatment.

Associations of low density lipoprotein particle composition with atherogenicity

PURPOSE OF REVIEW

A growing body of data suggests that in addition to LDL-cholesterol concentrations, compositional properties of LDL, including size and fatty acid composition, are important in determining the relative degree of atherogenicity. This review examines current research in this field to evaluate which properties of LDL may most directly influence the risk of coronary heart disease.

RECENT FINDINGS

The presence of small dense LDL has been correlated with an increased risk of coronary heart disease, but this has not been shown to be fully independent of related factors such as elevated plasma triacylglycerol concentrations. An increased susceptibility of small dense LDL to in-vitro oxidation has also been demonstrated, but its importance to coronary heart disease risk has not been established. Other studies have found that the presence of enlarged LDL, modified (oleate enriched) fatty acyl composition of LDL, and higher numbers of LDL particles in plasma also are endpoints associated with an increased risk of coronary heart disease.

SUMMARY

LDL size may indicate a metabolic condition associated with increased CHD risk as opposed to the direct promotion of atherosclerosis by specific particle types of LDL. In most claims of detrimental effects of small dense LDL, neither LDL particle concentrations nor the fatty acid composition of the particles were established, both factors being important in contributing to the atherogenic potential of LDL. The predisposition to premature coronary heart disease cannot currently be objectively assigned to any one type of LDL particle.

Simultaneous determination by GC-MS of epoxy and hydroxy FA as their methoxy derivatives

We report on a capillary GC-MS method for the quantitative analysis of hydroxy and epoxy FA. Catalytic hydrogenation of lipid extracts produces stable saturated lipids. Saponification followed by methylation with boron trifluoride in the presence of methanol converts FA to methyl esters and epoxy groups to methoxy-hydroxy groups. These compounds are purified from nonoxidized methyl esters using solid phase extraction. Derivatization of the hydroxy group using tetramethylammonium hydroxide forms methoxy and vicinal dimethoxy FAME. When subjected to EI-MS, fragmentation gives two characteristic ion fragments for each epoxy and hydroxy positional isomer. Quantitative measurements were achieved using uniformly labeled hydroxy and epoxy 13C FA as internal standards. Epoxy and hydroxy FA were identified in both plasma and adipose tissue of men, and the levels of hydroxy and epoxy in these tissues were related. The levels of hydroxy isomers were typical of oxidation of linoleic acid, whereas epoxy isomers were characteristic of oxidation of oleic acid.

Optimisation of the management of patients with coronary heart disease and type 2 diabetes mellitus

Type 2 diabetes mellitus is a prevalent disease in Westernised society, and more than 50% of individuals with diabetes mellitus die from cardiovascular causes. The underlying metabolic defect of type 2 diabetes mellitus is a combination of insulin resistance and decreased secretion of insulin by pancreatic beta-cells. Insulin resistance commonly precedes the onset of type 2 diabetes mellitus and is usually associated with a metabolic syndrome including hypertension, dyslipidaemia and obesity. Treatment of known cardiovascular risk factors, including hyperglycaemia, dyslipidaemia, hypertension and smoking, plays a key role in delaying the onset and progression of coronary heart disease (CHD) and other forms of atherosclerosis in patients with diabetes mellitus. Sulphonylureas should be used with caution in patients with CHD but aspirin (acetylsalicylic acid), beta-blockers and ACE inhibitors play an important role in the medical management of patients with established coronary artery disease and diabetes mellitus. Patients with diabetes mellitus represent a higher risk group of patients after both percutaneous and surgical coronary revascularisation and the decision regarding the choice of revascularisation procedure should take into account angiographic characteristics, clinical status and patient preference. Patients presenting with diabetes mellitus and acute myocardial infarction should be considered for reperfusion therapy with either urgent thrombolytic therapy or primary percutaneous coronary intervention.

The mortality and cancer morbidity experience of employees at the Chapelcross plant of British Nuclear Fuels plc, 1955-95

The results presented here are from the follow-up of the cohort of workers ever employed at the Chapelcross site of British Nuclear Fuels plc (BNFL) between 1955 and 1995. The study cohort consists of 2628 workers, 2249 of whom were male, who were first employed at the plant before 1 January 1996, and who have 63967 person-years of follow-up. The mean follow-up period is 24.3 years. The 2209 members of the cohort (84%) classified as radiation workers accumulated 185.1 person-sieverts of external radiation; their median cumulative dose was 39.1 mSv, and 95% of their cumulative doses were less than 339.3 mSv. The Chapelcross workers show the usual 'healthy worker' effect. To the end of 1995, there were 528 deaths among the total cohort (20%), including 449 (20%) amongst the radiation workers. When the dose was unlagged, a statistically significant association was noted between cancer registrations of the buccal cavity and pharynx and dose, based on five cases. When the dose was lagged by 10 years, a statistically significant excess relative risk was noted between all cancer morbidity and dose, 1.80 Sv(-1) (0.03 to 4.45), based on 162 cases. This result is driven by the non-significant, but high excess relative risk estimates from the 12 prostatic cancer registrations. A statistically significant association is noted between the eight deaths amongst radiation workers who had prostatic cancer as the underlying cause of mortality and cumulative external radiation dose when the dose was lagged by 0, 2 and 10 years. The association is unlikely to be causal. The finding has little biological plausibility as the strength of the association weakened as the dose lagging increased; it was strongest when the dose was unlagged and disappeared when the dose was lagged by 20 years. None of the workers who was registered for or died from prostatic cancer had ever been monitored for exposure to tritium or to 51Cr, 59Fe, 60Co or 65Zn. There is no evidence to date amongst the Chapelcross cohort of increased risk for cancers considered to be radiogenic based on studies of populations exposed to high levels of radiation.

Menopause-induced changes in lipid fractions and total fatty acids in plasma

The purpose of the present work was to evaluate the changes induced by the menopause in plasma lipids and total fatty acids.

METHODS

35 post-menopausal and 25 non-postmenopausal women were included in the study. Plasma triglycerides (TG), total cholesterol (TC) and HDL-C concentrations were detemined enzymatically. Plasma fatty acids were determined by capillary gas chromatography.

RESULTS

Total cholesterol was higher (p < 0.05) in the postmenopausal women (6.18 +/- 0.77 mmol/l vs. 5.21 +/- 0.85 mmol/l). No significant changes were observed, however, in TG, HDL-C or LDL-C. The study of plasma fatty acids showed the post-menopausal women to have raised levels (p < 0.05) of stearic acid (C18:0), oleic acid (C18:1), and decrease of arachidonic acid (C20:4). Also noteworthy was the significant decrease (p < 0.001) of the desaturation index D5 (3.82 +/- 1.75) in the post-menopausal women. The SHBG level was lower (p <0.001) in the post-menopausal women (55.98 +/- 20nmol/l) than in the non-menopausal women (68.36 +/- 30 nmol/l). Multivariate analysis revealed correlation between menopause and SHBG (r = -0.3904, p < 0.05), D5 (r = -0.500, p < 0.001), TC (r = 0.3137, p <0.05), stearic acid (r = 03564, p < 0.05) and oleic acid (r = 0.2954, p < 0.05).

CONCLUSION

In post-menopausal women, as well as higher total cholesterol, the alterations in plasma fatty acids may constitute an important risk factor for cardiovascular diseases.

Weight cycling-induced alteration in fatty acid metabolism

Epidemiological studies have suggested that repeated weight cycling over time may increase the risk of coronary heart disease. The mechanism involved remains poorly understood, but the change in lipid metabolism during weight cycling has been offered as a possible explanation. The present study investigated the effect of weight cycling on the size and fatty acid composition of rat fat pads as well as serum cholesterol, triglyceride, glucose, insulin, and glucagon in rats. Two consecutive weight cycles were induced by 40% energy restriction followed by ad libitum refeeding of either a moderate-fat (MF; 22% energy) or a high-fat (HF; 45% energy) diet. The lipogenic enzymes, including fatty acid synthase, acetyl-CoA carboxylase, malic enzyme, pyruvate kinase, and lipoprotein lipase in the weight-cycled (WC) rats fed only the HF diet, yielded an overshoot of activities at the end of two weight cycles. These changes were accompanied by an 80% increase in the size of the adipocyte and a 40-50% increase in the size of perirenal and epididymal fat tissues in HF-WC rats. Regardless of whether the rats were fed the HF or MF diet, all WC rats showed a gradual reduction in linoleic and alpha-linolenic acid and an increase in palmitic, palmitoleic, and stearic acid in total body lipid. It is concluded that weight cycling in rats may promote body fatness if an HF diet is consumed and can significantly alter whole body fatty acid balance irrespective of whether they consumed an MF or HF diet. Most importantly, the weight cycling led to an overshoot or fluctuation of serum cholesterol, triglyceride, glucose, insulin, and glucagon. If weight cycling is associated with an increased risk of cardiovascular disease, then, part of the mechanism may involve the changes in these risk factors.

Essential fatty acids and cardiovascular disease: the Edinburgh Artery Study

The aim of this study was to determine whether plasma and red cell fatty acid levels were associated with cardiovascular disease, and whether any association was independent of other major risk factors. Over 1100 subjects were examined in a random sample survey of the general population (the Edinburgh Artery Study). Fatty acids were measured in three plasma fractions (triglyceride, cholesteryl ester and phospholipid) and in red cell phospholipids. Fatty acid levels in groups with cardiovascular disease (myocardial infarction (MI), angina and lower limb disease) were compared with a no disease group. In the cholesteryl ester and phospholipid fractions there were significantly lower levels of eicosapentaenoic acid in the MI group on univariate analysis (p<0.05), but not when adjusted for age, sex, smoking and systolic blood pressure using logistic regression. In the red cell fraction, alpha-linolenic acid was significantly lower in those with stroke (p<0.01) and lower limb disease (p<0.05). Linoleic acid was significantly raised in the triglyceride fraction in those with MI, probably reflecting recent dietary changes. There were significant increases in dihomo-gamma-linolenic acid in the phospholipid and red cell fractions in those with MI, and in the phospholipid fraction in the stroke group. These results do not support the hypothesis that n-6 fatty acids are protective against cardiovascular disease, although there may be some beneficial effects of the n-3 fatty acid, alpha-linolenic acid. Results from cross-sectional surveys must, however, be interpreted with caution because the presence of disease may affect dietary intake.

Effects of a prudent diet containing either lean beef and mutton or fish and skinless chicken on the plasma lipoproteins and fatty acid composition of triacylglycerol and cholesteryl ester of hypercholesterolemic subjects11This study was sponsored by the Meat Board of South Africa

In this two-phase crossover study, 39 hypercholesterolemic subjects followed a prudent diet with either lean red meat or fish and skinless chicken (treatment groups), and 13 subjects (reference group) followed their habitual diet. Fasting blood samples were analyzed for plasma total cholesterol, triacylglycerol (TAG), high density lipoprotein cholesterol (HDL-C), low density lipoprotein one- and two-cholesterol, apolipoprotein-B, very low density lipoprotein cholesterol, and very low density lipoprotein TAG, and fatty acid composition of plasma TAG and cholesteryl ester (CE). Body mass and blood pressure were determined. Seven-day dietary records were kept once at baseline and twice during the treatment periods. Significant differences were observed in dietary intake between the baseline and treatment diets and between the two treatment diets. HDL-C (P < 0.05) and diastolic blood pressure (P < 0.01) were higher in patients on the red meat diet than in those on the chicken-fish diet. No other significant differences in lipoproteins were observed between the effects of the two treatment diets. The linoleic acid (%), eicosapentaenoic acid (%), and the eicosapentaenoic acid/arachidonic acid ratios in TAG and CE were higher (P < 0.01) in subjects on the chicken-fish diet than in those on the red meat diet. In conclusion, this study showed that the effect of two lipid-lowering diets containing either lean red meat or skinless chicken and fish on the atherogenic lipoproteins did not differ significantly. A prudent diet with skinless chicken and fish, however, had a more favorable effect on the fatty acid composition of the plasma TAG and the CE than did the lean red meat diet.

Geographic, demographic, and socioeconomic variations in the investigation and management of coronary heart disease in Scotland

OBJECTIVE

To determine whether age, sex, level of deprivation, and area of residence affect the likelihood of investigation and treatment of patients with coronary heart disease.

DESIGN, PATIENTS, AND INTERVENTIONS

Routine discharge data were used to identify patients admitted with acute myocardial infarction (AMI) between 1991 and 1993 inclusive. Record linkage provided the proportion undergoing angiography, percutaneous transluminal coronary angioplasty (PTCA), and coronary artery bypass grafting (CABG) over the following two years. Multiple logistic regression analysis was used to determine whether age, sex, deprivation, and area of residence were independently associated with progression to investigation and revascularisation.

SETTING

Mainland Scotland 1991 to 1995 inclusive.

MAIN OUTCOME MEASURES

Two year incidence of angiography, PTCA, and CABG. Results-36 838 patients were admitted with AMI. 4831 (13%) underwent angiography, 587 (2%) PTCA, and 1825 (5%) CABG. Women were significantly less likely to undergo angiography (p < 0.001) and CABG (p < 0.001) but more likely to undergo PTCA (p < 0.05). Older patients were less likely to undergo all three procedures (p < 0.001). Socioeconomic deprivation was associated with a reduced likelihood of both angiography and CABG (p < 0.001). There were significant geographic variations in all three modalities (p < 0.001).

CONCLUSION

Variations in investigation and management were demonstrated by age, sex, geography, and socioeconomic deprivation. These are unlikely to be accounted for by differences in need; differences in clinical practice are, therefore, likely.

Randomized controlled trial of gamma-linolenic acid and eicosapentaenoic acid in peripheral arterial disease

BACKGROUND AND AIMS

epidemiological studies suggest polyunsaturated fatty acids protect against the development of atherosclerosis. The aim of this study was to perform a randomized controlled trial of gamma-linolenic and eicosapentaenoic acids in patients with lower limb atherosclerosis. Main outcome measures were: cholesterol and lipoprotein concentrations; haemostatic and rheological variables; the ankle brachial pressure index; walking distance; and cardiovascular events and death.

METHODS

120 men and women with stable intermittent claudication were randomized to 2 years treatment with either a combination of gamma-linolenic and eicosapentaenoic acids, or placebo.

RESULTS

39 (65.0 cent) of those taking fatty acids and 36 (60.0 cent) of those taking placebo completed the trial. Lipid concentrations did not differ significantly during the trial. In those taking fatty acids, haematocrit was significantly higher than in the placebo group after 6 months (46.1 cent compared with 44.6 cent, P </= 0.01), and systolic blood pressure was significantly lower after 2 years (150|mmHg compared with 161.8|mmHg, </= 0.05). There was no difference in walking distance, but there was a small reduction in non-fatal coronary events in the fatty acid group (10 cent compared with 15 cent, P > 0.05).

CONCLUSIONS

a combination of polyunsaturated fatty acids produced a statistically significant reduction in systolic blood pressure, but no other significant benefits on risk factors. The trend towards fewer coronary events in those taking fatty acids warrants further investigation.

Dietary monounsaturated fatty acids promote aortic atherosclerosis in LDL receptor-null, human ApoB100-overexpressing transgenic mice

In mice with genetically engineered high levels of plasma low density lipoprotein (LDL), we tested the hypothesis that an increase in the dietary content of monounsaturated fatty acids but not of polyunsaturated fatty acids would promote atherosclerosis. The mouse model used was an LDL receptor-null, human apoB100-overexpressing strain. Six experimental groups of 19 to 38 mice of both sexes were established when the animals had reached 8 weeks of age. For the next 16 weeks, individual groups were fed either a commercial diet or prepared diets including fat as 10% of energy, with 5 different fatty acid enrichment patterns including the following: saturated (sat), cis and trans monounsaturated (mono), and n-3 and n-6 polyunsaturated (poly). Highly significant differences (ANOVA, P<0. 0001) in LDL cholesterol (in mg/dL) were found, with the rank order at 16 weeks being trans mono (mean, 1390)>sat (922)=cis mono (869)=n-6 poly (868)>n-3 poly (652)>commercial diet (526). Significant elevations in very low density lipoprotein cholesterol were also found in the trans and cis mono and sat groups, and triacylglycerol concentrations were also elevated in all groups. High density lipoprotein cholesterol concentrations were consistently low (20 to 50 mg/dL) in all groups. Highly significant differences (ANOVA, P<0.0001) in atherosclerosis, quantified by measurement of aortic cholesteryl ester concentration (mg/g protein) among dietary fatty acid groups were found, with the order being trans mono (mean, 50.4)>sat (35.6)=cis mono (34.6)>n-6 poly (18. 3)=n-3 poly (9.7)=commercial diet (7.8). Therefore, in this mouse model of hypercholesterolemia, dietary cis or trans monounsaturated fat did not protect against atherosclerosis development, whereas aortic atherosclerosis in either of the polyunsaturated fat groups was significantly less than in the saturated fat group.

Insulin and coronary artery disease: is syndrome X the unifying hypothesis?

OBJECTIVE

To review data supporting the hypothesis that syndrome X plays a major role in the pathogenesis of coronary artery disease (CAD), and the effects of lifestyle factors and pharmacologic interventions on insulin, other metabolic parameters, and outcomes.

DATA SOURCES

MEDLINE (January 1966-August 1997) and Current Contents database searches identified applicable English-language experimental trials, epidemiologic studies, reviews, and editorials.

STUDY SELECTION AND DATA EXTRACTION

Studies that were included addressed the role of insulin resistance and hyperinsulinemia in the pathogenesis of CAD or the effects of lifestyle factors and pharmacologic interventions on metabolic parameters and outcomes.

DATA SYNTHESIS

The main characteristics of syndrome X are hyperinsulinemia and insulin resistance. These result in secondary syndrome X features, including hyperglycemia, increased very-low-density lipoprotein concentrations, decreased high-density lipoprotein cholesterol, and hypertension. Insulin resistance is worsened by obesity, and insulin has been shown to contribute to the development of hypertension. Other studies demonstrate that smoking adversely affects glucose and insulin concentrations. Animal studies have linked hyperinsulinemia and atherogenesis. These animal data have been confirmed by several large prospective and population studies that have identified associations between hyperinsulinemia and CAD.

CONCLUSIONS

Strong evidence links insulin resistance and hyperinsulinemia to CAD. Lifestyle modifications play an important role in decreasing cardiovascular risk, and clinicians should strongly encourage such changes. Clinicians must also carefully consider the effects of antihypertensive, antihyperglycemic, and antidyslipidemic agents on patients' metabolic profiles when choosing appropriate therapeutic regimens. However, outcome data on many potentially beneficial agents, including calcium antagonists, alpha 1-adrenergic antagonists, angiotensin-converting enzyme inhibitors, metformin, acarbose, and troglitazone, are not yet available.

Hepatic origin of cholesteryl oleate in coronary artery atherosclerosis in African green monkeys. Enrichment by dietary monounsaturated fat

Relationships among plasma lipoprotein cholesterol, cholesterol secretion by the isolated, perfused liver, and coronary artery atherosclerosis were examined in African green monkeys fed diets containing cholesterol and 35% of calories as fat enriched in polyunsaturated, monounsaturated, or saturated fatty acids. The livers of animals fed monounsaturated fat had significantly higher cholesteryl ester concentrations (8.5 mg/g wet wt) than the livers of the other diet groups (3.65 and 3.37 mg/g wet wt for saturated and polyunsaturated fat groups, respectively) and this concentration was highly correlated with plasma cholesterol and apoB concentrations in each diet group. Cholesteryl oleate was 58 and 74. 5% of the liver cholesteryl ester in the saturated and monounsaturated fat groups. In each diet group, perfusate cholesteryl ester accumulation rate was highly correlated to liver and plasma cholesterol concentrations, and to plasma LDL cholesteryl ester content. Cholesteryl oleate was 48 and 67% of the cholesteryl esters that accumulated in perfusate in the saturated and monounsaturated fat animals, and this percentage was very highly correlated (r = -0.9) with plasma apoB concentration. Finally, in these two diet groups, liver perfusate cholesteryl ester accumulation rate was well correlated (r >/= 0.8) to coronary artery cholesteryl ester concentration, a measure of the extent of coronary artery atherosclerosis that occurred over the five years of diet induction in these animals. These data define an important role for the liver in the cholesteryl oleate enrichment of the plasma lipoproteins in the saturated and monounsaturated fat groups, and demonstrate strong relationships among hepatic cholesteryl ester concentration, cholesteryl ester secretion, and LDL particle cholesteryl ester content. The high correlation between liver cholesteryl ester secretion and coronary artery atherosclerosis provides the first direct demonstration of the high degree of importance of hepatic cholesteryl ester secretion in the development of this disease process. The remarkable degree of enrichment of cholesteryl oleate in plasma cholesteryl esters of the monounsaturated fat group may account for the relatively high amount of coronary artery atherosclerosis in this group.

Comparison of plasma lipid and lipoprotein profiles in hypertensive black versus white men. Department of Veterans Affairs Cooperative Study Group on Antihypertensive Agents

An abnormal plasma lipid and lipoprotein profile is an independent and strong predictor of mortality and morbidity from coronary artery disease (CAD). We report on plasma lipid and lipoprotein profiles with respect to race, age, obesity, blood pressure (BP), smoking, and drinking history in 1,292 male veterans with a diastolic BP of 95 to 109 mm Hg while off antihypertensive medications. Blacks had 24% (p <0.001) lower triglycerides than whites. In contrast, the following parameters were higher in blacks than in whites by the indicated percentages: high-density lipoprotein (HDL) cholesterol, 16% (p <0.001); HDL2 cholesterol, 36% (p <0.001); apolipoprotein (Apo) A1, 8% (p <0.001); HDL/low-density lipoprotein (LDL), 18% (p = 0.018); HDL2/LDL, 36% (p = 0.031); HDL2/HDL3, 21% (p <0.001); and Apo A1/Apo B, 15% (p <0.001). Triglycerides were unchanged up to age 60, but were lower by 24% (p <0.001) in those aged > or = 70. Apo A1 levels were higher (p <0.001), whereas LDL cholesterol was lower (p <0.008) in moderate alcohol consumers versus abstainers. Triglycerides were higher (p <0.001), whereas HDL, HDL2 cholesterol, and Apo A1 were lower (p <0.001) with increasing obesity. Moderate alcohol consumption had a strong favorable effect on HDL, HDL2, and HDL3 cholesterol among subjects of normal weight, but this effect was diminished in obese subjects. Total and LDL cholesterol were higher by 6.4% (p = 0.001) and 9.4% (p <0.003), respectively, whereas HDL cholesterol remained unchanged in those with diastolic BP of 105 to 109 mm Hg versus those with diastolic BP of 95 to 99 mm Hg. We conclude that hypertensive black men have lipid and lipoprotein profiles indicative of less CAD risk than white men. Chronic moderate alcohol consumption correlates with a favorable plasma lipid and lipoprotein profile in normal, but not obese, men. Obesity is associated with an adverse plasma lipid and lipoprotein profile. Thus, race, alcohol intake, and obesity may be important modifiers of CAD in untreated hypertensive men.

The serum cholesterol ester fatty acid composition but not the serum concentration of alpha tocopherol predicts the development of myocardial infarction in 50-year-old men: 19 years follow-up

A low serum tocopherol concentration and a low proportion of linoleic acid in plasma cholesterol esters have been reported to be associated with coronary heart disease. This study was undertaken to evaluate the predictive importance of the serum cholesterol ester fatty acid composition and serum tocopherol concentration in addition to established risk factors for myocardial infarction. The study comprised 2322 fifty-year-old men who participated in a health survey in 1970-1973 regarding risk factors for coronary heart disease. The proportions of myristic, palmitic, palmitoleic, and dihomogammalinolenic acid were significantly higher in 1970-1973 in subjects who suffered myocardial infarction during the following 19 years, while the proportion of linoleic acid was lower, than in those who remained healthy. Serum tocopherol did not differ significantly between the groups. LDL/HDL ratio, systolic blood pressure, and arachidonic acid/dihomogammalinolenic acid ratio were significant independent discriminators between cases and controls in a stepwise logistic regression analysis. This study suggests that middle-aged men who later develop a myocardial infarction are characterized not only by conventional risk factors but also by an altered fatty acid composition of serum cholesterol esters, with a low arachidonic to dihomogammalinolenic acid ratio, indicating reduced delta 5 desaturase activity. This may imply that changes in the quality of dietary fat intake, or an altered capacity to metabolize fatty acids in the body, could precede the development of coronary heart disease.

Improvement of insulin sensitivity and dyslipidemia with a new alpha-glucosidase inhibitor, voglibose, in nondiabetic hyperinsulinemic subjects

This study was undertaken to investigate the effect of voglibose, a new alpha-glucosidase inhibitor, on glucose and lipid metabolism in nondiabetic hyperinsulinemic subjects. Sixteen nondiabetic subjects with hyperinsulinemia participated in the study. They were divided into two groups of eight subjects with normal (NGT) and impaired (IGT) glucose tolerance. A meal tolerance test and a 75-g oral glucose tolerance test (OGTT) were performed at the beginning (baseline phase) and end (treatment phase) of the 12-week treatment. Serum lipid levels were measured every 4 weeks throughout the treatment phase and follow-up phase (8 weeks). All patients received 1 0.2-mg tablet of voglibose before each test meal (3 tablets per day). We also measured insulin sensitivity using a steady-state plasma glucose (SSPG) method in eight normotensive hyperinsulinemic subjects and in eight age- and body mass index (BMI)-matched control subjects before and after the drug treatment. Voglibose significantly decreased the responses of plasma glucose and insulin on the meal tolerance test. The area under the curve for 2-hour insulin during the 75-g OGTT decreased after treatment, whereas that for 2-hour glucose did not change before and after treatment. SSPG was reduced after treatment, indicating improvement of insulin sensitivity. Moreover, treatment with voglibose resulted in a significant decline of triglyceride level and an elevation of high-density lipoprotein (HDL) cholesterol and apolipoprotein A-1. These values returned to near-baseline levels after the drug was discontinued. Consequently, we conclude that this agent not only has a direct hypoglycemic effect through decreased absorption of carbohydrate, but also a hypoinsulinemic and hypolipidemic effect via improved insulin sensitivity.

Effect of systemic administration of isotretinoin on blood lipids and fatty acids in acne patients

BACKGROUND

In many studies, an increase in total cholesterol and triglycerides with isotretinoin therapy have been shown and investigators have commented on potential cardiovascular risk. A low intake of linoleic acid, the main essential fatty acid in man, may act as an independent risk factor for coronary heart disease. In vitro etretin alters both the incorporation of extracellular fatty acids into cell membranes and the fatty acid composition of the cell membrane itself. It is, therefore, important to establish whether isotetinoin has any effect on the metabolism of polyunsaturated fatty acids.

METHODS

The effect of treatment with isotretinoin for 4 months on the metabolism of polyunsaturated fatty acids in patients with acne was assessed. Quantitative total cholesterol and triglycerides as well as plasma phospholipid, triglycerides, and cholesteryl ester fatty acids were measured in 12 patients and red cell phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol fatty acids were measured in 13 patients before and after isotretinoin therapy.

RESULTS

There was a significant increase in the concentrations of cholesterol (P < 0.02) and triglycerides (P < 0.04) during treatment. There was no significant difference is plasma phospholipids, triglycerides, and cholesterol esters, or in the red cell phosphatidylethanolamine, phosphatidylcholine, and phosphatidylinositol during isotretinoin therapy.

CONCLUSIONS

This study failed to demonstrate any effect of isotretinon on the metabolism of polyunsaturated fatty acids. There was a significant increase in total cholesterol and triglyceride levels following isotretinoin therapy supporting the findings of many previous studies.

Abnormal membrane concentrations of 20 and 22-carbon essential fatty acids: a common link between risk factors and coronary and peripheral vascular disease?

Although elevated levels of cholesterol are associated with increased risks of coronary and peripheral vascular disease, the association frequently fails to provide a causative explanation at the individual level. New hypotheses are required which, whether or not they are correct, will provide new lines of research. It is proposed here that the causes of vascular disease are abnormal membrane phospholipid concentrations of the 20-carbon and 22-carbon essential fatty acids (EFAs) of the n-6 and n-3 series. These levels become abnormal with ageing, with stress and in response to smoking, high cholesterol levels and high saturated fat intakes. They are also abnormal in patients with diabetes and hypertension. The effects of these EFAs and their metabolites include lowering of triglycerides, elevation of high-density lipoprotein (HDL)-cholesterol, reduction of blood pressure, vasodilatation, reduction of fibrinogen levels and inhibition of platelet aggregation and of cardiac arrhythmias. Prospective studies have shown that abnormal levels of these fatty acids are predictive of future coronary death. Controlled trials of treatment have demonstrated that provision of the fatty acids reduces both coronary and total mortality. Further experimental and clinical investigations of the roles of appropriate membrane concentrations of these fatty acids are justified.

Heart and arterial disease risk factor levels in the Scottish workforce: cross-sectional study of risk factor levels. The SHARP Committee. Scottish Heart and Arterial Disease Risk Prevention

Between 1991-93 a specially trained team of nurses screened 19,435 subjects from various workforces in different regions of Scotland to identify cardiovascular disease risk factor levels in the Scottish working population. The regions visited provided a wide geographical spread. Name, age, occupation, social class, personal and family history of cardiovascular disease were recorded along with consumption of tobacco, alcohol and salt. Height and weight were measured and Body Mass Index (BMI) calculated; systolic (SBP) and diastolic (DBP) blood pressure, blood glucose and blood cholesterol were also measured. The proportion of social class I-IV in men studied was 49, 22, 22, and 7% respectively and in women 28, 29, 39 and 5%. Fifty two per cent of men and 61% of women had never smoked and 24% of men and 17% of women had previously stopped smoking. Twenty one per cent of both sexes were still smoking. Eighteen per cent of men drank more than 21 units of alcohol per week and 3.4% of women drank more than 14 units per week. Mean values of SBP and DBP increased with age and the percentage with hypertension (> or = 148/90 mm Hg) in men and women was 5% and 24% respectively. Mean BMI was slightly higher in men than women (25.3 & 24.5 respectively) and there was a significant (p < 0.01) rise in BMI with age in both sexes. Forty six per cent of men and 32% of women were classified as overweight (BMI > 25) while 9% of men and 9% of women were classified as obese (BMI > 30).(ABSTRACT TRUNCATED AT 250 WORDS)

Fatty acid composition of adipose tissue in humans. Implications for the dietary fat-serum cholesterol-CHD issue

Interest in studies of the fatty acid composition of adipose tissue has arised from the dietary fat-serum cholesterol-CHD issue. The fatty acid composition of depot fat reflects that of the diet. Gas chromatography analysis of subcutaneous adipose tissue yield objective and reliable information of the fatty acid composition of the habitual diet of individuals. A relative linoleic acid deficiency, as depicted by low adipose tissue linoleate levels, has not convincingly been demonstrated to be of importance in the aetiology of atherosclerosis or related disorders. Inverse correlation between n-3 fatty acids and coronary artery disease has been reported. Dietary supplementation of n-3 fatty acids may be of relevance, however the risk of hazardous side-effects do exist. In conclusion, a simple reduction of the total fat content of the diet still seems to be the most important strategy for prevention of atherosclerosis.

Plasma levels of apolipoproteins A-1 and B in Indian patients with angiographically defined coronary artery disease

Apolipoproteins A-1 and B concentration were measured in 201 Indian patients (32 females; 169 males) undergoing elective diagnostic coronary arteriography in order to assess the predictive power of apolipoproteins as a 'marker' of coronary artery disease (CAD). This association was also compared to that of other traditional risk factors: age, hypertension, diabetes, family history, smoking and plasma levels of total cholesterol, triglycerides, low and high density lipoproteins. The apolipoprotein (Apo) A-1 levels averaged 82.9 +/- 18.9 mg/dl in the normal coronary group (n = 43) and 76.0 +/- 18.1 mg/dl in the group with coronary artery disease (n = 158). The average Apo B levels in the normal coronary group and coronary artery disease group were 67.8 +/- 17.7 mg/dl and 78.9 +/- 19.5 mg/dl, respectively. Overall Apo B and triglyceride levels (of all lipid measures) showed larger univariate difference between the normal group (no coronary artery disease) and the group with coronary artery disease. The variable with strongest predictive power for coronary artery disease was the ratio of Apo A-1 to Apo B. These findings were confirmed using multiple logistic regression analysis adjusting for age and other traditional risk factors. Our results indicate that the measurement of apolipoproteins A-1 and B provide a better marker for predicting the presence of coronary artery disease as compared to traditional lipid measures. Overall the levels of these apolipoproteins seem to be lower in Indian population as compared to those reported from the West.

Coronary heart disease rates within a small urban area in Belgium

STUDY OBJECTIVE

To identify geographical differences in coronary heart disease (CHD) attack rates in a small urban area and to relate these to indicators of socioeconomic class.

DESIGN

CHD attack rates were calculated from data of the Ghent MONICA myocardial infarct register for the period 1983-87. The city of Ghent is subdivided into 201 sectors based on morphological, and socioeconomic characteristics. During the national census of 1981, the main determinants of residential differentiation were measured. These sector variables were linked with the CHD attack rates.

PATIENTS

All residents of the city aged 25-69 years are prospectively followed with regard to heart attacks. Between 1982 and 1987, 1728 suffered an acute heart attack according to MONICA criteria.

MAIN RESULTS

Significant (p < 0.05) differences in age and sex standarised attack rates were observed between city sectors. These differences were related to an index of socioeconomic status.

CONCLUSION

Within a small urban area, significant geographical differences occur in CHD attack rates and these are related to socioeconomic status.

Plasma essential fatty acids, cigarette smoking, and dietary antioxidants in peripheral arterial disease. A population-based case-control study

The aim of this study was to determine the levels of plasma fatty acids in patients with peripheral arterial disease and in control subjects and to identify whether any risks of disease related to these differences were influenced by smoking and antioxidant intake. A random sample of 1592 men and women aged 55 to 74 years was selected from the general population (the Edinburgh Artery Study), from which 153 cases of peripheral arterial disease were identified by the presence of intermittent claudication and low ankle systolic pressures at rest and during reactive hyperemia; these were matched by age and sex to 153 control subjects with no evidence of cardiovascular disease. In 113 case and 122 control subjects, fatty acid levels were measured in three plasma fractions (triglyceride, cholesteryl ester, and phospholipid), and smoking habits and dietary antioxidant intake were determined by questionnaire. Arachidonic acid, eicosapentaenoic acid, docosahexaenoic acid, and docosapentaenoic acid (DPA/n-3) were significantly lower in the cases than controls (P < .01). More case than control subjects were current or exsmokers (86% versus 50%; P < .001), and the case subjects had lower vitamin C intake (64.8 mg versus 71.1 mg; P < .05). By logistic regression adjustment for smoking and vitamin C intake, only DPA/n-3 (odds ratio, 0.19; P < .01) and arachidonic acid (odds ratio, 0.44; P < .05) remained significantly related to disease; only DPA/n-3 reduced the risk associated with smoking. We conclude that in subjects with peripheral arterial disease compared with healthy control subjects, the largest differences occurred in fatty acids of the n-3 series, particularly DPA/n-3.(ABSTRACT TRUNCATED AT 250 WORDS)

Linoleic acid and risk of sudden cardiac death

OBJECTIVE

To test the hypothesis that the essential fatty acid, linoleic acid, measured in adipose tissue as an indicator of long term dietary intake, is inversely related to the risk of sudden cardiac death.

DESIGN

A population case-control study.

SETTING

A regional health district.

SUBJECTS

84 men (age 25-64 years) who died instantaneously or within 24 hours of the onset of symptoms with no history of coronary heart disease or medically treated hyperlipidaemia, and in whom coronary artery disease was diagnosed at postmortem examination as the primary cause of death, were compared with 292 age (to within two years) and sex matched healthy controls and their partners drawn from the general practitioners' records with whom the cases were registered.

MAIN OUTCOME MEASURES

Fatty acid composition of adipose tissue and the risk of sudden cardiac death.

RESULTS

Linoleic acid in adipose tissue was inversely related to the risk of sudden cardiac death. The estimated relative risk (95% CI) of sudden cardiac death was 5.7 (1.8 to 17.9) for the lowest quintile and 4.0 (1.2 to 12.9) for the next quintile of adipose linoleic acid in the control population when compared with the highest quintile. This inverse relation was independent of age, reported smoking habits, history of hypertension, and diabetes, although there was a close association with cigarette smoking. The estimated adjusted proportionate increase in risk (95% CI) of sudden cardiac death was 1.14 (1.03 to 1.23) for every 1% reduction of linoleic acid in adipose tissue.

CONCLUSIONS

The percentage content of linoleic acid in adipose tissue was inversely related to the risk of sudden cardiac death. Populations with a high risk of sudden cardiac death may benefit from increasing their dietary intake of polyunsaturated fatty acid oils, principally from cereals and vegetables.

Relationship between insulin resistance and coronary heart disease in diabetes mellitus and the general population: a critical appraisal

The hypothesis that a causal relationship exists between insulin resistance and atherogenesis was first proposed over 23 years ago, and has given rise to a vast literature. Biological plausibility has been lent to the hypothesis by studies in which insulin has produced some effects in cell and tissue culture, and in vivo in arterial tissue, consistent with our understanding of the pathogenesis of atherosclerosis. Clinical studies demonstrating a complex interrelationship between insulin resistance-hyperinsulinaemia and established risk factors for CHD--hypertension, hypertriglyceridaemia, low HDL cholesterol levels and abdominal obesity--are reviewed. A review of the studies examining an independent association between hyperinsulinaemia and coronary heart disease is presented. Cross-sectional studies in both the general population and diabetes support the relationship; however, prospective studies in the general population provide limited and inconsistent support for this hypothesis and highlight the confounding effects of blood pressure, dyslipidaemia and obesity on the effects of hyperinsulinaemia. In subjects with NIDDM and impaired glucose tolerance, prospective studies have not shown a deleterious effect of insulin treatment per se, nor have they consistently shown a significantly increased risk for those with higher endogenous insulin levels. The therapeutic implications of the evidence to date are less complex and involve weight reduction by diet and exercise, the lowering of elevated blood pressure with metabolically neutral agents, the judicious use of lipid lowering drugs and, in diabetes, the use of insulin where clinically indicated.

Fatty acid composition in total phospholipids of human coronary arteries in sudden cardiac death

A study was made of the fatty acid composition of the total phospholipid fraction of human coronary arteries in 30 cases of sudden cardiac death due to ischaemic heart disease (aged 40 +/- 5 years, mean +/- S.D.) and in 29 controls (mostly traffic accident victims, aged 45 +/- 6 years). The coronary arteries from cases of sudden cardiac death showed more atherosclerotic lesions than those of controls (P < 0.001). The percentages of palmitic acid (16:0) and linoleic acid (18:2(n-6)) were significantly higher and the percentage of arachidonic acid (20:4(n-6)) and of all the other major polyunsaturated fatty acids, both n-6 and n-3, was significantly lower in cases of sudden cardiac death than in controls. In conclusion, this study showed increased percentages of saturated and reduced percentages of polyunsaturated fatty acids, except linoleic acid, in total phospholipids of human coronary arteries in cases of sudden cardiac death. The results suggest an impaired metabolism of linoleic acid, possibly due to a decreased delta-6-desaturase activity in the coronary artery wall in cases of sudden cardiac death.

Comparison of the effect of the amount and degree of unsaturation of dietary fat on plasma low density lipoproteins in vervet monkeys

The effects of the degree of unsaturation and of the amount of dietary fat on low density lipoprotein (LDL) concentration and composition were determined in vervet monkeys. Diets with fat contents of 41, 31 and 18% energy, each with a low and a high polyunsaturated to saturated fatty acid ratio (P/S; 0.27-0.38 and 1.13-1.47) were fed to six female vervet monkeys for two months. Another six females were given a low fat, high P/S diet for the same period of time, to serve as a reference. The cholesterol contents of the diets were low (21-33 mg per day) and relatively constant. LDL cholesterol concentrations decreased significantly (P < or = 0.01) when the dietary fat content decreased from 31 to 18% of energy. The dietary P/S ratio only affected LDL cholesterol concentrations during moderate (31% of energy) fat intake, where LDL cholesterol increased (P < or = 0.01) with a decrease in dietary P/S. Substantial individual variations were observed in LDL cholesterol concentration responses to dietary fat changes. The changes in LDL cholesterol concentrations were the result of changes in the concentration of LDL particles, as the molecular composition did not differ significantly between dietary periods. The high density lipoprotein cholesterol and the plasma triacylglycerol concentrations were not influenced by the dietary fat changes. During the high P/S diets, the percentage of 18:2 (linoleic acid) increased (P < or = 0.01) and that of 18:1 (oleic acid) decreased (P < or = 0.01) in LDL esterified cholesterol, as compared to the low P/S diets. In adipose tissue triacylglycerol the percentage of 18:2 was three times higher (P < or = 0.01) during the high P/S diets than during the low P/S diets.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of nicotinic acid treatment on fatty acid composition of plasma lipids and adipose tissue in hyperlipidaemia

Effects of 6-week treatment with 4 g daily of nicotinic acid on fatty acid composition in different serum lipids and in adipose tissue glycerides were studied in 31 hyperlipidemic patients. The percentages of eight fatty acids in triglycerides, phospholipids and cholesteryl esters of whole plasma as well as in subcutaneous adipose tissue glycerides were measured. Nicotinic acid treatment produced decreases in triglyceride and total cholesterol concentrations of VLDL and LDL, whereas HDL total cholesterol levels in serum increased after drug therapy, all p less than 0.01. There were reductions in the relative contents of myristic acid in plasma phospholipids (from 0.4% to 0.3%; p less than 0.05) and cholesteryl esters (from 0.9% to 0.7%; p less than 0.001). There were decreases in the percentages of stearic acid in plasma phospholipids (from 17.0% to 15.0%) and cholesteryl esters (from 1.2% to 1.0%; both p less than 0.001). The relative contents of polyunsaturated fatty acids, mainly linoleic acid, in plasma phospholipids were increased (from 32% to 33.5%; p less than 0.05). There were reductions in the linolenic acid contents of adipose tissue (from 1.5% to 1.1%) and plasma triglycerides (from 1.1% to 0.8%), both p less than 0.05, possibly indicating increased conversion of linolenic acid to prostaglandins. There was no relationship between changes in the percentages of individual fatty acids and changes in triglyceride or total cholesterol levels of whole serum and its VLDL, LDL and HDL fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Relationship between the degree of unsaturation of dietary fatty acids and adipose tissue fatty acids assessed by natural-abundance 13C magnetic resonance spectroscopy in man

Natural-abundance 13C magnetic resonance spectroscopy was used for determining noninvasively the relative concentration of mono- and polyunsaturated fatty acids of adipose tissue in two groups of volunteers. The first consisted of subjects who had followed a fat-reduced diet for at least half a year before the 13C measurements. The second were control subjects who were on a usual high-fat diet. The ratio of unsaturated to total fatty acids in adipose tissue determined by 13C MRS correlated significantly with the same ratio in fat of the diet composition estimated by a dietician according to food records. The results indicate that 13C MRS is capable of assessing the degree of unsaturation of dietary fatty acids consumed during the preceding months.

Hypertension, the endothelial cell, and the vascular complications of diabetes mellitus

Hypertension is a major factor that contributes to the development of the vascular complications of diabetes mellitus, which primarily include atherosclerosis, nephropathy, and retinopathy. The mechanism of the pathophysiological effects of hypertension lies at the cellular level in the blood vessel wall, which intimately involves the function and interaction of the endothelial and vascular smooth muscle cells. Both hypertension and diabetes mellitus alter endothelial cell structure and function. In large and medium size vessels and in the kidney, endothelial dysfunction leads to enhanced growth and vasoconstriction of vascular smooth muscle cells and mesangial cells, respectively. These changes in the cells of smooth muscle lineage play a key role in the development of both atherosclerosis and glomerulosclerosis. In diabetic retinopathy, damage and altered growth of retinal capillary endothelial cells is the major pathophysiological insult leading to proliferative lesions of the retina. Thus, the endothelium emerges as a key target organ of damage in diabetes mellitus; this damage is enhanced in the presence of hypertension. An overall approach to the understanding and treatment of diabetes mellitus and its complications will be to elucidate the mechanisms of vascular disease and endothelial cell dysfunction that occur in the setting of hypertension and diabetes.

Traditional risk-factor profile fails to explain striking geographical differences in IHD mortality among middle-aged men. The project "myocardial infarction in mid-Sweden"

An east-west gradient in cardiovascular mortality has been reported from the region of mid-Sweden. Postal questionnaire studies found that the risk factor distributions among middle-aged men were similar in areas with striking differences in cardiovascular mortality. In this study, 120 randomly selected 50-year-old men in two high mortality communities in the west and 120 men from two low mortality communities in the east were invited to a health survey in which serum lipids and other risk factors were analysed. Total serum cholesterol, LDL-cholesterol, HDL-cholesterol, and triglyceride levels were similar. Among fatty acids, stearic acid was high and arachidonic acid was low in the high mortality area. The levels of other traditional risk factors were the same. After taking these differences into account, the mortality differences remain large.

Smoking status and dietary fats

BACKGROUND

There have been several recent reports of differences in the diet of smokers versus that of nonsmokers. This has broad implications for assessment of disease risk associated with diet or smoking.

METHODS

We examined dietary fats for several categories of smoking status in a large cross-sectional data set. The annual risk factor survey of a cardiovascular disease prevention trial in three pairs of upper Midwest communities includes 3,495 subjects ranging in age from 24 to 75. Smoking was assessed by self-report and thiocyanate, and diet by the Willett questionnaire. Dietary comparisons of smokers, recent quitters, long-term (over 1 year) quitters, and never-smokers were conducted.

RESULTS

Previous findings of lower polyunsaturated fat intake in smokers were confirmed and extended by finding significantly elevated polyunsaturate intake among those who had quit smoking within the last year. The source of these differences is unclear, but the differences are large enough to constitute a significant contribution to disease risk for smokers or a protective effect for recent quitters.

CONCLUSIONS

Future research examining risks associated with smoking or diet should control for the interaction of the two factors. The dietary differences in recent quitters, whether caused by a conscious decision to improve diet, a change in taste perception as a result of quitting, or simply the habits of those smokers who are able to quit, need further exploration.