Free Cholesterol Bioavailability and Atherosclerosis

PURPOSE OF REVIEW

As both a cholesterol acceptor and carrier in the reverse cholesterol transport (RCT) pathway, high-density lipoprotein (HDL) is putatively atheroprotective. However, current pharmacological therapies to increase plasma HDL cholesterol (HDL-c) concentration have paradoxically failed to prevent or reduce atherosclerosis and cardiovascular disease (CVD). Given that free cholesterol (FC) transfer between surfaces of lipoproteins and cells is reversible, excess plasma FC can be transferred to the cells of peripheral tissue sites resulting in atherosclerosis. Here, we summarize potential mechanisms contributing to this paradox and highlight the role of excess free cholesterol (FC) bioavailability in atherosclerosis vs. atheroprotection.

RECENT FINDINGS

Recent findings have established a complex relationship between HDL-c concentration and atherosclerosis. Systemic scavenger receptor class B type 1 (SR-B1) knock out (KO) mice exhibit with increased diet-induced atherosclerosis despite having an elevated plasma HDL-c concentration compared to wild type (WT) mice. The greater bioavailability of HDL-FC in SR-B1 vs. WT mice is associated with a higher FC content in multiple cell types and tissue sites. These results suggest that dysfunctional HDL with high FC bioavailability is atheroprone despite high HDL-c concentration. Past oversimplification of HDL-c involvement in cholesterol transport has led to the failures in HDL targeted therapy. Evidence suggests that FC-mediated functionality of HDL is of higher importance than its quantity; as a result, deciphering the regulatory mechanisms by which HDL-FC bioavailability can induce atherosclerosis can have far-reaching clinical implications.

Within-Trial Cost-Effectiveness of a Structured Lifestyle Intervention in Adults With Overweight/Obesity and Type 2 Diabetes: Results From the Action for Health in Diabetes (Look AHEAD) Study

OBJECTIVE

To assess the cost-effectiveness (CE) of an intensive lifestyle intervention (ILI) compared with standard diabetes support and education (DSE) in adults with overweight/obesity and type 2 diabetes, as implemented in the Action for Health in Diabetes study.

RESEARCH DESIGN AND METHODS

Data were from 4,827 participants during their first 9 years of study participation from 2001 to 2012. Information on Health Utilities Index Mark 2 (HUI-2) and HUI-3, Short-Form 6D (SF-6D), and Feeling Thermometer (FT), cost of delivering the interventions, and health expenditures was collected during the study. CE was measured by incremental CE ratios (ICERs) in costs per quality-adjusted life year (QALY). Future costs and QALYs were discounted at 3% annually. Costs were in 2012 U.S. dollars.

RESULTS

Over the 9 years studied, the mean cumulative intervention costs and mean cumulative health care expenditures were $11,275 and $64,453 per person for ILI and $887 and $68,174 for DSE. Thus, ILI cost $6,666 more per person than DSE. Additional QALYs gained by ILI were not statistically significant measured by the HUIs and were 0.07 and 0.15, respectively, measured by SF-6D and FT. The ICERs ranged from no health benefit with a higher cost based on HUIs to $96,458/QALY and $43,169/QALY, respectively, based on SF-6D and FT.

CONCLUSIONS

Whether ILI was cost-effective over the 9-year period is unclear because different health utility measures led to different conclusions.

Intensive Weight Loss Intervention and Cancer Risk in Adults with Type 2 Diabetes: Analysis of the Look AHEAD Randomized Clinical Trial

OBJECTIVE

This study was designed to determine whether intensive lifestyle intervention (ILI) aimed at weight loss lowers cancer incidence and mortality.

METHODS

Data from the Look AHEAD trial were examined to investigate whether participants randomized to ILI designed for weight loss would have reduced overall cancer incidence, obesity-related cancer incidence, and cancer mortality, as compared with the diabetes support and education (DSE) comparison group. This analysis included 4,859 participants without a cancer diagnosis at baseline except for nonmelanoma skin cancer.

RESULTS

After a median follow-up of 11 years, 684 participants (332 in ILI and 352 in DSE) were diagnosed with cancer. The incidence rates of obesity-related cancers were 6.1 and 7.3 per 1,000 person-years in ILI and DSE, respectively, with a hazard ratio (HR) of 0.84 (95% CI: 0.68-1.04). There was no significant difference between the two groups in total cancer incidence (HR, 0.93; 95% CI: 0.80-1.08), incidence of nonobesity-related cancers (HR, 1.02; 95% CI: 0.83-1.27), or total cancer mortality (HR, 0.92; 95% CI: 0.68-1.25).

CONCLUSIONS

An ILI aimed at weight loss lowered incidence of obesity-related cancers by 16% in adults with overweight or obesity and type 2 diabetes. The study sample size likely lacked power to determine effect sizes of this magnitude and smaller.

Weight Change 2 Years After Termination of the Intensive Lifestyle Intervention in the Look AHEAD Study

OBJECTIVE

This study evaluated weight changes after cessation of the 10-year intensive lifestyle intervention (ILI) in the Look AHEAD (Action for Health in Diabetes) study. It was hypothesized that ILI participants would be more likely to gain weight during the 2-year observational period following termination of weight-loss-maintenance counseling than would participants in the diabetes support and education (DSE) control group.

METHODS

Look AHEAD was a randomized controlled trial that compared the effects of ILI and DSE on cardiovascular morbidity and mortality in participants with overweight/obesity and type 2 diabetes. Look AHEAD was converted to an observational study in September 2012.

RESULTS

Two years after the end of the intervention (EOI), ILI and DSE participants lost a mean  (SE) of 1.2  (0.2) kg and 1.8  (0.2) kg, respectively (P = 0.003). In addition, 31% of ILI and 23.9% of DSE participants gained ≥ 2% (P < 0.001) of EOI weight, whereas 36.3% and 45.9% of the respective groups lost ≥ 2% of EOI weight (P = 0.001). Two years after the EOI, ILI participants reported greater use of weight-control behaviors than DSE participants.

CONCLUSIONS

Both groups lost weight during the 2-year follow-up period, but more ILI than DSE participants gained ≥ 2% of EOI weight. Further understanding is needed of factors that affected long-term weight change in both groups.

History of Cardiovascular Disease, Intensive Lifestyle Intervention, and Cardiovascular Outcomes in the Look AHEAD Trial

OBJECTIVE

To examine the effects of an intensive lifestyle intervention (ILI) on cardiovascular disease (CVD), the Action for Health in Diabetes (Look AHEAD) trial randomized 5,145 participants with type 2 diabetes and overweight/obesity to a ILI or diabetes support and education. Although the primary outcome did not differ between the groups, there was suggestive evidence of heterogeneity for prespecified baseline CVD history subgroups (interaction P = 0.063). Event rates were higher in the ILI group among those with a CVD history (hazard ratio 1.13 [95% CI: 0.90-1.41]) and lower among those without CVD (hazard ratio 0.86 [95% CI: 0.72-1.02]).

METHODS

This study conducted post hoc analyses of the rates of the primary composite outcome and components, adjudicated cardiovascular death, nonfatal myocardial infarction (MI), stroke, and hospitalization for angina, as well as three secondary composite cardiovascular outcomes.

RESULTS

Interaction P values for the primary and two secondary composites were similar (0.060-0.064). Of components, the interaction was significant for nonfatal MI (P = 0.035). This interaction was not due to confounding by baseline variables, different intervention responses for weight loss and physical fitness, or hypoglycemic events. In those with a CVD history, statin use was high and similar by group. In those without a CVD history, low-density lipoprotein cholesterol levels were higher (P = 0.003) and statin use was lower (P ≤ 0.001) in the ILI group.

CONCLUSIONS

Intervention response heterogeneity was significant for nonfatal MI. Response heterogeneity may need consideration in a CVD-outcome trial design.

Physical Function Following a Long-Term Lifestyle Intervention Among Middle Aged and Older Adults With Type 2 Diabetes: The Look AHEAD Study

Background

Lifestyle interventions have been shown to improve physical function over the short term; however, whether these benefits are sustainable is unknown. The long-term effects of an intensive lifestyle intervention (ILI) on physical function were assessed using a randomized post-test design in the Look AHEAD trial.

Methods

Overweight and obese (body mass index ≥ 25 kg/m2) middle-aged and older adults (aged 45-76 years at enrollment) with type 2 diabetes enrolled in Look AHEAD, a trial evaluating an ILI designed to achieve weight loss through caloric restriction and increased physical activity compared to diabetes support and education (DSE), underwent standardized assessments of performance-based physical function including a 4- and 400-m walk, lower extremity physical performance (expanded Short Physical Performance Battery, SPPBexp), and grip strength approximately 11 years postrandomization and 1.5 years after the intervention was stopped (n = 3,783).

Results

Individuals randomized to ILI had lower odds of slow gait speed (<0.8 m/s) compared to those randomized to DSE (adjusted OR [95% CI]: 0.84 [0.71 to 0.99]). Individuals randomized to ILI also had faster gait speed over 4- and 400-m (adjusted mean difference [95% CI]: 0.019 [0.007 to 0.031] m/s, p = .002, and 0.023 [0.012 to 0.034] m/sec, p < .0001, respectively) and higher SPPBexp scores (0.037 [0.011 to 0.063], p = .005) compared to those randomized to DSE. The intervention effect was slightly larger for SPPBexp scores among older versus younger participants (0.081 [0.038 to 0.124] vs 0.013 [-0.021 to 0.047], p = .01).

Conclusions

An intensive lifestyle intervention has modest but significant long-term benefits on physical function in overweight and obese middle-aged and older adults with type 2 diabetes.

ClinicalTrials.gov Identifier

NCT00017953.

Effect of a long-term intensive lifestyle intervention on prevalence of cognitive impairment

OBJECTIVE

To assess whether an average of 10 years of lifestyle intervention designed to reduce weight and increase physical activity lowers the prevalence of cognitive impairment among adults at increased risk due to type 2 diabetes and obesity or overweight.

METHODS

Central adjudication of mild cognitive impairment and probable dementia was based on standardized cognitive test battery scores administered to 3,802 individuals who had been randomly assigned, with equal probability, to either the lifestyle intervention or the diabetes support and education control. When scores fell below a prespecified threshold, functional information was obtained through proxy interview.

RESULTS

Compared with control, the intensive lifestyle intervention induced and maintained marked differences in weight loss and self-reported physical activity throughout follow-up. At an average (range) of 11.4 (9.5-13.5) years after enrollment, when participants' mean age was 69.6 (54.9-87.2) years, the prevalence of mild cognitive impairment and probable dementia was 6.4% and 1.8%, respectively, in the intervention group, compared with 6.6% and 1.8%, respectively, in the control group (p = 0.93). The lack of an intervention effect on the prevalence of cognitive impairment was consistent among individuals grouped by cardiovascular disease history, diabetes duration, sex, and APOE ε4 allele status (all p ≥ 0.50). However, there was evidence (p = 0.03) that the intervention effect ranged from benefit to harm across participants ordered from lowest to highest baseline BMI.

CONCLUSIONS

Ten years of behavioral weight loss intervention did not result in an overall difference in the prevalence of cognitive impairment among overweight or obese adults with type 2 diabetes.

CLINICALTRIALSGOV IDENTIFIER

NCT00017953 (Action for Health in Diabetes).

LEVEL OF EVIDENCE

This study provides Class II evidence that for overweight adults with type 2 diabetes, a lifestyle intervention designed to reduce weight and increase physical activity does not lower the risk of cognitive impairment.

Association of the magnitude of weight loss and changes in physical fitness with long-term cardiovascular disease outcomes in overweight or obese people with type 2 diabetes: a post-hoc analysis of the Look AHEAD randomised clinical trial

BACKGROUND

Findings from the Look AHEAD trial showed no significant reductions in the primary outcome of cardiovascular disease incidence in adults with type 2 diabetes randomly assigned to an intensive lifestyle intervention for weight loss compared with those randomly assigned to diabetes support and education (control). We examined whether the incidence of cardiovascular disease in Look AHEAD varied by changes in weight or fitness.

METHODS

Look AHEAD was a randomised clinical trial done at 16 clinical sites in the USA, recruiting patients from Aug 22, 2001, to April 30, 2004. In the trial, 5145 overweight or obese adults aged 45-76 years with type 2 diabetes were assigned (1:1) to an intensive lifestyle intervention or diabetes support and education. In this observational, post-hoc analysis, we examined the association of magnitude of weight loss and fitness change over the first year with incidence of cardiovascular disease. The primary outcome of the trial and of this analysis was a composite of death from cardiovascular causes, non-fatal acute myocardial infarction, non-fatal stroke, or admission to hospital for angina. The secondary outcome included the same indices plus coronary artery bypass grafting, carotid endartectomy, percutaneous coronary intervention, hospitalisation for congestive heart failure, peripheral vascular disease, or total mortality. We adjusted analyses for baseline differences in weight or fitness, demographic characteristics, and risk factors for cardiovascular disease. The Look AHEAD trial is registered with ClinicalTrials.gov, number NCT00017953.

FINDINGS

For the analyses related to weight change, we excluded 311 ineligible participants, leaving a population of 4834; for the analyses related to fitness change, we excluded 739 participants, leaving a population of 4406. In analyses of the full cohort (ie, combining both study groups), over a median 10·2 years of follow-up (IQR 9·5-10·7), individuals who lost at least 10% of their bodyweight in the first year of the study had a 21% lower risk of the primary outcome (adjusted hazard ratio [HR] 0·79, 95% CI 0·64-0·98; p=0·034) and a 24% reduced risk of the secondary outcome (adjusted HR 0·76, 95% CI 0·63-0·91; p=0·003) compared with individuals with stable weight or weight gain. Achieving an increase of at least 2 metabolic equivalents in fitness change was associated with a significant reduction in the secondary outcome (adjusted HR 0·77, 95% CI 0·61-0·96; p=0·023) but not the primary outcome (adjusted HR 0·78, 0·60-1·03; p=0·079). In analyses treating the control group as the reference group, participants in the intensive lifestyle intervention group who lost at least 10% of their bodyweight had a 20% lower risk of the primary outcome (adjusted HR 0·80, 95% CI 0·65-0·99; p=0·039), and a 21% lower risk of the secondary outcome (adjusted HR 0·79, 95% CI 0·66-0·95; p=0·011); however, change in fitness was not significantly associated with a change in the primary outcome.

INTERPRETATION

The results of this post-hoc analysis of Look AHEAD suggest an association between the magnitude of weight loss and incidence of cardiovascular disease in people with type 2 diabetes. These findings suggest a need to continue to refine approaches to identify individuals who are most likely to benefit from lifestyle interventions and to develop strategies to improve the magnitude of sustained weight loss with lifestyle interventions.

FUNDING

US National Institute of Diabetes and Digestive and Kidney Diseases.

Impact of an intensive lifestyle intervention on use and cost of medical services among overweight and obese adults with type 2 diabetes: the action for health in diabetes

OBJECTIVE

To assess the relative impact of an intensive lifestyle intervention (ILI) on use and costs of health care within the Look AHEAD trial.

RESEARCH DESIGN AND METHODS

A total of 5,121 overweight or obese adults with type 2 diabetes were randomly assigned to an ILI that promoted weight loss or to a comparison condition of diabetes support and education (DSE). Use and costs of health-care services were recorded across an average of 10 years.

RESULTS

ILI led to reductions in annual hospitalizations (11%, P = 0.004), hospital days (15%, P = 0.01), and number of medications (6%, P < 0.001), resulting in cost savings for hospitalization (10%, P = 0.04) and medication (7%, P < 0.001). ILI produced a mean relative per-person 10-year cost savings of $5,280 (95% CI 3,385-7,175); however, these were not evident among individuals with a history of cardiovascular disease.

CONCLUSIONS

Compared with DSE over 10 years, ILI participants had fewer hospitalizations, fewer medications, and lower health-care costs.

Impact of intensive lifestyle intervention on depression and health-related quality of life in type 2 diabetes: the Look AHEAD Trial

OBJECTIVE

We examined the effects of an intensive lifestyle intervention (ILI), compared with a diabetes support and education (DSE) control intervention, on long-term changes in depression symptoms, antidepressant medication (ADM) use, and health-related quality of life (HRQoL) in overweight/obese individuals with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Look AHEAD was a multisite randomized controlled trial of 5,145 overweight/obese participants assigned to ILI (designed to produce weight loss) or DSE and followed for a median of 9.6 years. The Beck Depression Inventory (BDI) was administered at baseline, annually at years 1-4, and again at year 8. Mean BDI scores and incidence of BDI scores ≥10, indicative of likely mild or greater depression, were examined. Annually through year 10, participants reported their ADM use and completed the Medical Outcomes Study Short Form 36 (SF-36) questionnaire, which yields physical component summary (PCS) and mental component summary (MCS) scores.

RESULTS

ILI significantly reduced the incidence of mild or greater depression symptoms (BDI scores ≥10) compared with DSE (hazard ratio [HR] = 0.85; 95% CI 0.75-0.97; P = 0.0145). Although SF-36 PCS scores worsened over time in both groups, ILI participants reported better physical function than DSE throughout the first 8 years (all P values <0.01). There were no significant differences between treatment arms in the proportion of participants who used ADMs or in SF-36 MCS scores.

CONCLUSIONS

ILI for overweight/obese patients with type 2 diabetes may reduce the risk of developing clinically significant symptoms of depression and preserve physical HRQoL. These findings should be considered when evaluating the potential benefits of ILIs.

Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes

BACKGROUND

Weight loss is recommended for overweight or obese patients with type 2 diabetes on the basis of short-term studies, but long-term effects on cardiovascular disease remain unknown. We examined whether an intensive lifestyle intervention for weight loss would decrease cardiovascular morbidity and mortality among such patients.

METHODS

In 16 study centers in the United States, we randomly assigned 5145 overweight or obese patients with type 2 diabetes to participate in an intensive lifestyle intervention that promoted weight loss through decreased caloric intake and increased physical activity (intervention group) or to receive diabetes support and education (control group). The primary outcome was a composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for angina during a maximum follow-up of 13.5 years.

RESULTS

The trial was stopped early on the basis of a futility analysis when the median follow-up was 9.6 years. Weight loss was greater in the intervention group than in the control group throughout the study (8.6% vs. 0.7% at 1 year; 6.0% vs. 3.5% at study end). The intensive lifestyle intervention also produced greater reductions in glycated hemoglobin and greater initial improvements in fitness and all cardiovascular risk factors, except for low-density-lipoprotein cholesterol levels. The primary outcome occurred in 403 patients in the intervention group and in 418 in the control group (1.83 and 1.92 events per 100 person-years, respectively; hazard ratio in the intervention group, 0.95; 95% confidence interval, 0.83 to 1.09; P=0.51).

CONCLUSIONS

An intensive lifestyle intervention focusing on weight loss did not reduce the rate of cardiovascular events in overweight or obese adults with type 2 diabetes. (Funded by the National Institutes of Health and others; Look AHEAD ClinicalTrials.gov number, NCT00017953.).

Cardiovascular effects of intensive lifestyle intervention in type 2 diabetes

BACKGROUND

Weight loss is recommended for overweight or obese patients with type 2 diabetes on the basis of short-term studies, but long-term effects on cardiovascular disease remain unknown. We examined whether an intensive lifestyle intervention for weight loss would decrease cardiovascular morbidity and mortality among such patients.

METHODS

In 16 study centers in the United States, we randomly assigned 5145 overweight or obese patients with type 2 diabetes to participate in an intensive lifestyle intervention that promoted weight loss through decreased caloric intake and increased physical activity (intervention group) or to receive diabetes support and education (control group). The primary outcome was a composite of death from cardiovascular causes, nonfatal myocardial infarction, nonfatal stroke, or hospitalization for angina during a maximum follow-up of 13.5 years.

RESULTS

The trial was stopped early on the basis of a futility analysis when the median follow-up was 9.6 years. Weight loss was greater in the intervention group than in the control group throughout the study (8.6% vs. 0.7% at 1 year; 6.0% vs. 3.5% at study end). The intensive lifestyle intervention also produced greater reductions in glycated hemoglobin and greater initial improvements in fitness and all cardiovascular risk factors, except for low-density-lipoprotein cholesterol levels. The primary outcome occurred in 403 patients in the intervention group and in 418 in the control group (1.83 and 1.92 events per 100 person-years, respectively; hazard ratio in the intervention group, 0.95; 95% confidence interval, 0.83 to 1.09; P=0.51).

CONCLUSIONS

An intensive lifestyle intervention focusing on weight loss did not reduce the rate of cardiovascular events in overweight or obese adults with type 2 diabetes. (Funded by the National Institutes of Health and others; Look AHEAD ClinicalTrials.gov number, NCT00017953.).

Autophagy regulates mycobacterial uptake by modulation of scavenger receptors (P4215)

Autophagy and phagocytosis are highly conserved cellular functions involved in innate immunity. However, the nature of the interactions between these two critical processes remains essentially unknown. We evaluated the role of autophagy in regulating phagocytosis by measuring phagocytic activity in autophagy-deficient macrophages obtained from a myeloid-specific autophagy-related gene 7 knockout mice Atg7-/-. Importantly, in addition to increased mycobacterial growth, Atg7-/- macrophages exhibited higher bacterial uptake, when infected with Mycobacterium tuberculosis or M. tuberculosis var. bovis BCG. In addition, Atg7-/- mice, infected intranasally with BCG, showed increased bacterial loads and exacerbated inflammatory responses in lungs, compared to Atg7+/+ cells. Atg7-/- macrophages had increased surface expression of two class A scavenger receptors: macrophage receptor with collagenous structure MARCO and scavenger receptor-A. These findings were confirmed in Atg3-/-, Atg5-/- and Atg7-/- mouse embryonic fibroblasts. The increased surface expression of scavenger receptors was caused by increased activity of the transcription factor NF-E2-related factor 2 due to accumulation of p62 in autophagy-deficient macrophages. These new insights increase our understanding of host-pathogen relationship and suggest that therapeutic strategies against pathogens should be designed to include modulation of both phagocytosis and autophagy.

Choline deficiency causes reversible hepatic abnormalities in patients receiving parenteral nutrition: proof of a human choline requirement: a placebo-controlled trial

BACKGROUND

Previous studies have shown that plasma free choline concentrations are significantly decreased in many long-term home total parenteral nutrition (TPN) patients. Furthermore, low choline status has been associated with both hepatic morphologic and hepatic aminotransferase abnormalities. A preliminary pilot study suggested choline-supplemented TPN may be useful in reversal of these hepatic abnormalities.

METHODS

Fifteen patients (10 M, 5 F) who had required TPN for > or =80% of their nutritional needs were randomized to receive their usual TPN (n = 8), or TPN to which 2 g choline chloride had been added (n = 7) for 24 weeks. Baseline demographic data were similar between groups. Patients had CT scans of the liver and spleen, and blood for plasma free and phospholipid-bound choline, alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase, gamma glutamyl transferase (GGT), bilirubin, serum lipids, complete blood count (CBC), and chemistry profile obtained at baseline, and weeks 2, 4, 6, 12, 16, 20, 24, and 34. CT scans were analyzed for Hounsfield unit (HU) densities.

RESULTS

There were no significant differences in any measured parameters after 2 weeks. However, at 4 weeks, a significant difference in liver HU between groups was observed (13.3+/-5.0 HU [choline] vs 5.8+/-5.2 HU [placebo], p = .04). This significant trend continued through week 24. Recurrent hepatic steatosis and decreased HU were observed at week 34, 10 weeks after choline supplementation had been discontinued. A significant increase in the liver-spleen differential HU was also observed in the choline group (10.6+/-6.2 HU [choline] vs 1.3+/-3.3 HU [placebo], p = .01). Serum ALT decreased significantly (p = .01 to .05) in the choline group vs placebo at weeks 6,12, 20, and 24. Serum AST was significantly decreased in the choline group by week 24 (p = .02). The serum alkaline phosphatase was significantly reduced in the choline group at weeks 2, 12, 20, 24, and 34 (p = .02 to 0.07). Total bilirubin was normal in these patients and remained unchanged during the study. Serum GGT tended to decrease more in the choline group, but the greater decrease was not statistically significant.

CONCLUSIONS

Choline deficiency is a significant contributor to the development of TPN-associated liver disease. The data suggest choline is a required nutrient for long-term home TPN patients.

Hydrolysis of phospholipids by purified milk lipoprotein lipase. Effect of apoprotein CII, CIII, A and E, and synthetic fragments

Different pyrene-labeled phospholipid monolayer vesicles were used as substrates for the bovine milk lipoprotein lipase activity. The effects of synthetic fragments of apoprotein C II were measured on the hydrolysis of 1-myristoyl-2[9(1pyrenyl)-nonanoyl] phosphatidylcholine in vesicles: The activating capacity of fragments 30-78 and 43-78, 50-78 and 55-78, compared to entire apo CII, were similar to that obtained with hydrolysable triglycerides. Our study shows that the longer the carboxy terminal fragment is, the higher is the activation. The phospholipid hydrolysis activity represents in the presence of apo C II, 36% of the triglycerides hydrolysis activity. Phospholipid hydrolysis is less dependent on activator than triglycerides hydrolysis (100% and 300% of increase with apo CII for phosphatidyl-choline and triglycerides respectively). The ratio hydrolysis without apo C II/hydrolysis with apo CII was different when other phospholipids than myrystoyl-phospatidylcholine were assayed: phosphatidyl-serine, ethanolamine, -choline, -glycerol, or diglycerides and butanoylglycerols. Fragment CIII(1) (1-40) which did not bind to lipids, had no inhibitory effect. The entire sugar moiety and the first 40 amino acids are not required for the total inhibition of LPL. Inhibition was also obtained with Apo A I, A II,C I and fragments of apo E.

Short-term vitamin E supplementation before marathon running: a placebo-controlled trial

Gastrointestinal complaints and occult bleeding have been commonly described in marathon runners. We hypothesized that these complaints may arise from intestinal ischemia caused by the shunting of blood away from the splanchnic circulation during endurance racing followed by reperfusion injury. Studies in animal models have suggested prophylactic vitamin E supplementation may prevent this type of injury. We sought to determine if prerace vitamin E supplementation would prevent intestinal ischemia/reperfusion injury in humans. Forty subjects who planned to complete the 1996 Houston-Tennaco Marathon were randomized to receive vitamin E (1000 IU daily) or placebo (soya lecithin) for 2 wk before the race in a double-blinded trial. Inclusion criteria included no use of non-steroidal anti-inflammatory drugs (NSAIDs) within 24 d of the race or vitamin or mineral supplements containing vitamins C or E or selenium within 30 d of the race. Subjects were studied 2 wk before the race and immediately following the race. Blood was obtained for serum vitamin E and total lipid and salicylate concentrations. A solution of lactulose (5 g) and mannitol (2 g) was consumed and urine was collected for 6 h. Aliquots were assayed for lactulose and mannitol concentration. Stool samples were tested for occult blood and following the race subjects rated their nausea, abdominal pain, and cramping on a 1-5 scale. Twenty-six subjects (24 male, 2 female) completed the marathon. Finish times ranged between 2 h 43 min and 5 h 28 min. All subjects had heme-negative stool prerace and four developed heme-positive stool postrace, with no difference between vitamin E and placebo groups (Fisher's exact = 0.63). All had non-detectable salicylate concentrations pre- and postrace. Serum vitamin E concentration increased in botPP = 0.02 in the vitamin E group and 1.45 +/- 0.40 to 1.66 +/- 0.48 mg/dL in the placebo group, P = 0.02). However, the serum vitamin E: total lipid ratio increased significantly in the vitamin E-supplemented group (0.0022 +/- 0.0002 to 0.0051 +/- 0.0015, P = 0.02), but not in the placebo group (P = 0.25). Overall, the urinary lactulose:mannitol ratio increased from 0.03 +/- 0.02 to 0.06 +/- 0.08 postrace (P = 0.06) without difference between vitamin E or placebo groups. Intestinal permeability increased significantly more in those who developed occult bleeding. More subjects in the placebo group developed abdominal cramping (Fisher's exact = 0.04) and abdominal pain (Fisher's exact = 0.06), although there was no difference in severity between groups. There was no difference in the incidence of nausea and no diarrhea was reported by any subject. Intestinal permeability tends to increase and occult gastrointestinal bleeding occurs during endurance running, suggesting the occurrence of intestinal ischemia/reperfusion injury. Prerace supplementation with the antioxidant vitamin E had no effect on performance, intestinal injury, occult bleeding, or the severity of postrace gastrointestinal complaints. Vitamin E supplementation was associated with a decreased incidence of these complaints but had no effect on their severity.

Soluble cell adhesion molecules in hypertriglyceridemia and potential significance on monocyte adhesion

Hypertriglyceridemia may contribute to the development of atherosclerosis by increasing expression of cell adhesion molecules (CAMs). Although the cellular expression of CAMs is difficult to assess clinically, soluble forms of CAMs (sCAMs) are present in the circulation and may serve as markers for CAMs. In this study, we examined the association between sCAMs and other risk factors occurring with hypertriglyceridemia, the effect of triglyceride reduction on sCAM levels, and the role of soluble vascular cell adhesion molecule-1 (sVCAM-1) in monocyte adhesion in vitro. Compared with normal control subjects (n=20), patients with hypertriglyceridemia and low HDL (n=39) had significantly increased levels of soluble intercellular adhesion molecule-1 (sICAM-1) (316+/-28.8 versus 225+/-16.6 ng/mL), sVCAM-1 (743+/-52.2 versus 522+/-43.6 ng/mL), and soluble E-selectin (83+/-5.9 versus 49+/-3.6 ng/mL). ANCOVA showed that the higher sCAM levels in patients occurred independently of diabetes mellitus and other risk factors. In 27 patients who received purified n-3 fatty acid (Omacor) 4 g/d for > or =7 months, triglyceride level was reduced by 47+/-4.6%, sICAM-1 level was reduced by 9+/-3.4% (P=.02), and soluble E-selectin level was reduced by 16+/-3.2% (P<.0001), with the greatest reduction in diabetic patients. These results support previous in vitro data showing that disorders in triglyceride and HDL metabolism influence CAM expression and treatment with fish oils may alter vascular cell activation. In a parallel-plate flow chamber, recombinant sVCAM-1 at the concentration seen in patients significantly inhibited adhesion of monocytes to interleukin-1-stimulated cultured endothelial cells under conditions of flow by 27.5+/-7.2%. Thus, elevated sCAMs may negatively regulate monocyte adhesion.

Levels of soluble cell adhesion molecules in patients with dyslipidemia

BACKGROUND

Increased expression of cell adhesion molecules (CAMs) on the vascular endothelium has been postulated to play an important role in atherogenesis. Both in vitro and in vivo studies have suggested that dyslipidemia may increase expression of CAMs.

METHODS AND RESULTS

To determine whether dyslipidemia is associated with increased expression of CAMs, we examined the levels of soluble intercellular adhesion molecule 1 (sICAM-1), soluble vascular cell adhesion molecule 1 (sVCAM-1), and soluble E-selectin (sE-selectin) in individuals with either hypercholesterolemia or hypertriglyceridemia and in control subjects matched for age and sex. Patients with hypertriglyceridemia had significantly higher levels of sVCAM-1 (739 +/- 69 ng/mL) compared with patients with hypercholesterolemia (552 +/- 63 ng/mL) and control subjects (480 +/- 56 ng/mL). Levels of sICAM-1 were significantly increased in both the hypercholesterolemic and hypertriglyceridemic groups (298 +/- 29 and 342 +/- 31 ng/mL, respectively) compared with the control group (198 +/- 14 ng/mL). Levels of sE-selectin were significantly increased in hypercholesterolemic patients (74 +/- 9 ng/mL) compared with control subjects (48 +/- 5 ng/mL). Ten hypercholesterolemic patients were treated aggressively with atorvastatin alone or a combination of colestipol and either atorvastatin or simvastatin for a mean of 42 weeks and had an average LDL cholesterol reduction of 51%. Comparison of soluble CAMs before and after treatment showed a significant reduction only in sE-selectin (77 +/- 11 versus 56 +/- 6 ng/mL, P < or = .03) but not for sVCAM-1 or sICAM-1.

CONCLUSIONS

Although severe hyperlipidemia is associated with increased levels of soluble CAMs, aggressive lipid-lowering treatment had only limited effects on the levels. Increased levels of soluble CAMs in patients with hyperlipidemia may be a marker for atherosclerosis.

Human liver fatty acid binding protein cDNA and amino acid sequence. Functional and evolutionary implications

Human liver fatty acid binding protein (L-FABP) cDNA clones were identified in a liver cDNA library. The two longest clones were completely sequenced. The nucleotide sequence predicts a protein of 127 amino acid residues. Identity of the clones was confirmed by limited amino acid sequence analysis of purified human L-FABP peptides and Edman degradation of radiolabeled in vitro translated FABP. Statistical analysis of the amino acid and mRNA sequences of human L-FABP, rat L-FABP, rat intestinal (I-) FABP, and mouse 422 protein indicates that the human and rat L-FABPs are highly homologous and that L-FABP and I-FABP diverged a long time ago (approximately 650-690 million years ago), although they are more closely related to each other than either of them is to 422 protein. Secondary structure predictions from the primary sequence of human and rat L-FABP reveal a region (residues 12-30) that might be the putative fatty acid binding domain of the two L-FABPs. Knowledge of the primary amino acid sequence of L-FABP and possible functional domains will be pivotal in further defining and understanding the mechanism of ligand binding and transfer by this protein.

Kinetics and mechanism of association of human plasma apolipoproteins with dimyristoylphosphatidylcholine: effect of protein structure and lipid clusters on reaction rates

We have used a series of lipid-associating proteins with similar pI's and with molecular weights between 2280 and 28000 to study the mechanism of lipid-protein association. All of these polypeptides spontaneously associate with dimyristoylphosphatidylcholine (DMPC) to give quasi-discrete products. The reaction of the apoproteins with unsaturated lecithins is slow, if it occurs at all. Our data support the Kanehisa-Tsong cluster model [Kanehisa & Tsong (1978) J. Am. Chem. Soc. 100, 424] of lipid permeability in many of its qualitative aspects. These are (a) that the rate of lipid- protein association increases with decreasing polypeptide molecular weight, (b) that there is a small temperature dependence for the rate of association of small peptides with DMPC but with large polypeptides the temperature at which association with lipid is rapid is confined to the solid leads to fluid transition temperature (Tc) of DMPC, and (c) that the rate is asymmetric about Tc, with the change in the rate with respect to temperature below Tc being greater than at T greater than Tc. In addition, we have shown that unfolded monomeric proteins with a large number of exposed hydrophobic residues associate with DMPC faster than self-associated and/or folded proteins. Our data suggest that the association of some of the apoproteins with phospholipids is subject to kinetic control.