Are nutrition and physical activity associated with gut microbiota? A pilot study on a sample of healthy young adults

BACKGROUND

The literature shows that gut microbiota composition is related with health, and a lot of individual and outer factors may determine its variability. In particular, nutrition and exercise seem to influence the presence in the gut of the two major bacterial phyla of Firmicutes and Bacteroidetes.

STUDY DESIGN

An ongoing cross-sectional investigation is aimed to explore these associations in humans.

METHODS

Healthy Caucasian young adults were asked to provide a fecal sample in order to analyze their gut microbiome considering their Body Mass Index (BMI), adherence to Mediterranean diet and Physical Activity (PA) level.

RESULTS

A total of 59 participants (49.1% males, mean age 23.1 ± 3.14 years) were enrolled so far. Firmicutes (61.6±14.6) and Bacteroidetes (30.7 ± 13.3) showed the highest relative abundance in fecal samples. The Pearson's analysis showed a significant negative correlation between PA and Firmicutes (r =-0.270, p = 0.03). Linear regression confirmed a significant decrease of this phylum with the increase of PA (R2 = 0.07, p = 0.03).

CONCLUSIONS

These preliminary results suggest the association between physical activity and gut microbiota composition in healthy humans.

Physical activity and gut microbiota: a cross-sectional study

Background

The composition of gut microbiota, and in particular the intestinal abundance of the two main bacterial phyla of Firmicutes and Bacteroidetes, are associated with human health and diseases and may be conditioned by host and environmental factors such as age, gender and diet. The role of Physical Activity (PA) in determining gut microbiota composition has not been yet completely clarified. A cross-sectional study involving undergraduates from two Italian cities is ongoing to explore this relationship.

Methods

Students were invited to provide a fecal sample and to complete the International Physical Activity Questionnaire (IPAQ) in order to define their habitual PA level (inactive, minimally active, health enhancing physical activity -HEPA- active). Demographic and anthropometric information were also collected. DNA from fecal samples was analyzed through the 16S amplicon sequencing. Microbial composition and variability of the samples were evaluated on the light of participants' PA levels.

Results

A total of 153 students (47.7% males, mean age 22.4±2.9, mean BMI 22.3±2.7) participated to the study so far. Firmicutes and Bacteroidetes were the main represented phyla. An increase in Firmicutes (58.3±16 to 61.4±13.3, p = 0.68) and a reduction in Bacteroidetes (32.6±14.8 to 30.3±11.4, p = 0.51) have been registered with the increase of PA level. A higher variability (expressed as Shannon α-index) has been detected in minimally active (3.39±0.03) and HEPA-active (3.41±0) individuals respect to inactive subjects (3.35±0.07) (p = 0.05).

Conclusions

Even if they are not significant, these preliminary results suggest a relationship between PA levels and gut microbiota composition. An active lifestyle seems to be associated with a greater microbial diversity in the gut. Further researches are needed to explain these findings.

Key messages

Physical activity seems to be associated with gut microbiota composition. A greater variability in gut microbiota was found in active people.

Potential antimicrobial effects of photocatalytic nanothecnologies in hospital settings

BACKGROUND

Recently, several advanced technologies have been considered to reduce the microbial load in hospital environments and control Healthcare Associated Infections (HAIs) incidence. New strategies for preventing HAIs have continuously evolved, including enforcement of hygiene procedures by novel liquid biocides or no-touch technologies, self-disinfecting surfaces coated by heavy metals or light-activated photosensitizers such as Titanium Dioxide (TiO2) nanoparticles.

STUDY DESIGN

Review publications concerning the use of photocatalytic systems in hospital setting, focusing on products based on TiO².

METHODS

Specific keywords combinations were analitically searched in PubMed and Scopus databases.

RESULTS

Starting 80s-90s, over 2000 papers report "in vitro" studies on antimicrobial activity of TiO2 photocatalysis on several microorganisms including bacteria, viruses, fungi, yeasts, and antibiotic resistant strains. Besides, at least 4 selected papers addressed the potentials of this approach by "in field" studies, showing a widespread pool of applications in hospital and healthcare settings. However, the low number of available experiences and their heterogeneity represent major limitations to achieve a comprehensive final overview on effectiveness and feasibility of these technologies.

CONCLUSIONS

Photocatalytic systems based on TiO2 represent a promising strategy for hospital hygiene and HAI prevention. Additional "in field" studies are desirable in a next future to further evaluate and exploit this novel and interesting health technology.

Procedures in endoscope reprocessing and monitoring: an Italian survey

BACKGROUND

The high diffusion of endoscopes worldwide and the need for effective reprocessing methods requested the development of guidelines and implementation of surveillance procedures at local level.

STUDY DESIGN

In order to collect data on everyday's practice and adherence to available guidelines, endoscopy units from different public institutions were surveyed using a dedicated questionnaire.

METHODS

Between July and November 2015 a survey was carried in 12 main hospitals from 10 different Italian regions, involving 22 endoscopy units. The state of the art of national and international guidelines was investigated to compare the protocols adopted at local level.

RESULTS

In all the surveyed hospitals, the reprocessing activity is based on pre-established protocols in adherence with principal guidelines. Enzymatic detergents, which are recommended by the international guidelines, are used in 55.6% of units and peracetic acid is currently the most widely used chemical disinfectant. Discrepancies were observed in the application of periodic quality controls.

CONCLUSION

Updated guidelines are generally applied in reprocessing practice. Quality controls may represent a critical issue to improve effectiveness and surveillance. The whole of acquired data can promote a positive trend towards the application of best practices.

Development of the laboratory prototype "CavyPool" for assessing treatments and materials for swimming pools

BACKGROUND

Hygiene and surveillance in swimming pools are established by WHO Guidelines and national laws. Progress in water management and pool construction is revolutionizing the field, introducing new materials, systems, disinfection procedures or monitoring markers. Innovation advances challenge the upgrading of safety and quality in pools and the appropriate implementation of guidelines.

STUDY DESIGN

In order to provide a device for laboratory test, a prototype was realized and applied to study and compare swimming pool materials and treatments.

METHODS

A pool scale-model was engineered and evaluated by computational fluid dynamics algorithms. An automated real time monitoring assured steady state. Critical control points along the water circuit were made accessible to allow the placing of different biocides or water sampling. Simulations were safely performed in a standard hood. Materials for pool surfaces and pipelines were evaluated for biofilm formation under different disinfection conditions. Adherent microorganisms were assayed by mfDNA analysis using real time PCR.

RESULTS

The prototype reached the steady state within 5-25 hours under different conditions, showing chemical, physical and fluid-dynamic stability. A method was optimized for testing materials showing their different response to biofilm induction. Several innovative PVC samples displayed highest resistance to bacterial adhesion.

CONCLUSIONS

A device and method was developed for testing swimming pool hygienic parameters in laboratory. It allowed to test materials for pools hygiene and maintenance, including biofilm formation. It can be applied to simulate contaminations under different water treatments or disinfection strategies. It may support technical decisions and help policymakers in acquiring evidences for comparing or validating innovative solutions.

Monitoring biodiversity in libraries: a pilot study and perspectives for indoor air quality

Indoor Air Quality (IAQ) in libraries is influenced by the presence of specific factors which can impact on both paper storage as well as people health. Microclimatic conditions induce and support a biodiversity pattern involving environmental and anthropic microorganisms. We used a multidisciplinary monitoring model to characterize microflora biodiversity by Next Generation Sequencing (NGS). Biodiversity indexes were adapted to evaluate anthropic vs environmental pollution by combining Shannon mean index (H), species representativeness (E_H), human/environmental pollution ratio (SA) to better characterize the NGS output and acquire synthetic information on Indoor Air Microbial Biodiversity (IAMB). Results indicate a frequently low microbial load (IGCM/m³ < 1000) characterized by different species (n = 102), including several cellulose metabolizing bacteria. Workers and visitors appeared a relevant source of microbial contamination. Air biodiversity assayed by NGS seems a promising marker for studying IAQ.

[Comparison of cultural methods for the recovery of Pseudomonas aeruginosa: the UNI EN ISO 16266 reference method and the alternative method Pseudalert®]

BACKGROUND

For the water analysis, for Pseudomonas aeruginosa a presumptive positive result can be achieved in 40- 48 hours using the traditional membrane filtration technique followed by an additional 24-48 hour confirmation stage. Conversely, the Pseudalert Quanti-Tray™ method can give confirmed results after 24-28 hours. In this case, actively growing strains of Pseudomonas aeruginosa show a confirmed positive result when a specific enzyme cleaving the substrate in the reagent produces a blue fluorescence under 365 nm ultraviolet light. A comparison of the performance of the Pseudalert respect to the standard method was conducted using statistical methods.

METHODS

Drinking water was analyzed in parallel with the membrane filtration technique using Pseudomonas CN agar (UNI EN ISO 16266) and the Pseudalert. Confirmation test are requested by the standard method and although Pseudalert Quanti-Tray™ gives confirmed results, all the positive isolates were also confirmed. Data were analyzed by statistical methods.

RESULTS

For drinking water, Pseudalert showed a very high sensitivity (98,8%) and a high percentage of specificity (96,8%). From a total of 889 positive isolates, a very high confirmation rates (99,3%) was calculated. Statistical analyses confirmed that the two methods were not statistically different.

CONCLUSIONS

These results indicate that the Pseudalert produces confirmed results in a shorter time than the standard reference method allowing the detection of Pseudomonas aeruginosa with no further confirmation steps. It could be a valid alternative method for the water analysis.

Molecular enrichment for detection of S. aureus in recreational waters

The identification of rapid methods for the control of recreational water and of aquatic environments with similar characteristics is necessary to provide adequate levels of health safety for users. Molecular techniques have been proposed in recent years as a viable alternative to traditional microbiological methods, as they offer various advantages and are less time consuming than traditional tests. An innovative protocol based on molecular enrichment that allows the identification of low concentrations of Staphylococcus aureus in recreational water has been developed. The method is based on the specific amplification of prokaryotic genomic DNA by the usage of universal primers for 23S rDNA; subsequently, a second amplification step is performed with specific real-time polymerase chain reaction (PCR) primers and probe. This approach shows sensitivity levels similar to those observed with microbiological tests, with the additional benefits of the specificity typical of nucleic acids techniques. This methodology is easily applicable also to other microbiological parameters, representing an important milestone in hygiene monitoring by the detection of specific pollution indicators.

[Identification of candidate genes and expression profiles, as doping biomarkers]

Administration of prohibited substances to enhance athletic performance represents an emerging medical, social, ethical and legal issue. Traditional controls are based on direct detection of substances or their catabolites. However out-of-competition doping may not be easily revealed by standard analytical methods. Alternative indirect control strategies are based on the evaluation of mid- and long-term effects of doping in tissues. Drug-induced long-lasting changes of gene expression may be taken as effective indicators of doping exposure. To validate this approach, we used real-time PCR to monitor the expression pattern of selected genes in human haematopoietic cells exposed to nandrolone, insulin-like growth factor I (IGF-I) or growth hormone (GH). Some candidate genes were found significantly and consistently modulated by treatments. Nandrolone up-regulated AR, ESR2 and PGR in K562 cells, and SRD5A1, PPARA and JAK2 in Jurkat cells; IGF-I up-regulated EPOR and PGR in HL60 cells, and SRD5A1 in Jurkat; GH up-regulated SRD5A1 and GHR in K562. GATA1 expression was down-regulated in IGF-1-treated HL60, ESR2 was down-regulated in nandrolone-treated Jurkat, and AR and PGR were down-regulated in GH-treated Jurkat. This pilot study shows the potential of molecular biology-based strategies in anti-doping controls.

Detection of metazoan species as a public health issue: simple methods for the validation of food safety and quality

Species identification represents a critical issue in food chain safety and quality control. Several procedures are available to detect animal proteins in cattle feed or to trace transgenic foods. The most effective approach is based on the use of DNA as a marker. Amplification of DNA provides rapid, sensitive and specific protocols. Several target genes can be used, but new insights come from the mitochondrial genome, which is naturally amplified in each cell and shows a remarkable resistance to degradation. These are key points when analysing complex matrices such as foods, animal feedstuff or environmental samples. Traceability is important to prevent BSE or to monitor novel foods, such as genetically modified organisms. Amplification is commonly performed, but it requires expertise and a molecular biology laboratory to perform restriction analysis, electrophoresis or gel staining for the visualisation of results. Hereby, we consider a strategy based on multiple nested amplification and reverse hybridisation assay that virtually requires only a thermocycler and a water bath. The protocol is rapid and simple and can simultaneously detect different species in a DNA sample. This promising approach allows microarray developments, opening up to further perspectives. An international application has been published under the patent cooperation treaty. Presently, a ban on feeding ruminants on cattle-derived proteins is in force in Europe and USA. The identification of metazoan traces in a sample is not only a mere preventive measure for BSE, but represents a possible screening system for monitoring biotechnology products and procedures, as well as a quality control strategy to assure consumer's rights.

Cholesterol synthesis inhibitors do not reduce Lp(a) levels in normocholesterolemic patients

Experimental and clinical data suggest that activation of the LDL receptors by the use of HMG CoA reductase inhibitors, in the presence of normal plasma cholesterol levels, may result in a reduction of Lp(a) concentrations. This hypothesis has been tested in an open study on seven subjects with normal cholesterolemia but marked elevations of Lp(a) levels, three of whom received pravastatin and four simvastatin at standard therapeutic doses. While the two drugs caused the expected reduction of plasma total and LDL cholesterol levels, no significant changes in Lp(a) were noted. This study contradicts a prior clinical finding and suggests that HMG CoA reductase inhibitors are unlikely to reduce plasma Lp(a) levels even in the absence of hypercholesterolemia.

Triglycerides are major determinants of cholesterol esterification/transfer and HDL remodeling in human plasma

Lecithin:cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP) are responsible for the esterification of cell-derived cholesterol and for the transfer of newly synthesized cholesteryl esters (CE) from HDL to apoB-containing lipoproteins in human plasma. LCAT and CETP are also crucial factors in HDL remodeling, a process by which HDL particles with a high capacity for cell cholesterol uptake are generated in plasma. In the present study, cholesterol esterification and transfer were evaluated in 60 patients with isolated hypercholesterolemia (HC, n = 20) and isolated (HTG, n = 20) or mixed hypertriglyceridemia (MHTG, n = 20) and in 20 normolipidemic healthy individuals (NL). Cholesterol esterification rate (CER) and net CE transfer rate (CETR) were measured in whole plasma. LCAT and CETP concentrations were determined by specific immunoassays. HDL remodeling was analyzed by monitoring changes in HDL particle size distribution during incubation of whole plasma at 37 degrees C. Mean CER and CETR were 48% and 73% higher, respectively, in hypertriglyceridemic (HTG + MHTG) versus normotriglyceridemic individuals. HDL remodeling was also significantly accelerated in plasma from hypertriglyceridemic patients. Strong positive correlations were found in the total sample between plasma and VLDL triglyceride levels and CER (r = .722 and r = .642, respectively), CETR (r = .510 and r = .491, respectively), and HDL remodeling (r = .625 and r = .620, respectively). No differences in plasma LCAT and CETP concentrations were found among the various groups except for a tendency toward higher CETP levels in hypercholesterolemic patients (+51% in MHTG and +20% in HC) versus control subjects (NL). By stepwise regression analysis, VLDL triglyceride level was the sole significant predictor of CER and CETR and contributed significantly together with baseline HDL particle distribution to HDL remodeling. These results indicate that plasma triglyceride level is a major factor in the regulation of cholesterol esterification/transfer and HDL remodeling in human plasma, whereas LCAT/CETP concentrations play a minor role in the modulation of reverse cholesterol transport.

Non-invasive assessment of unstimulated forearm arterial compliance in human subjects. Impaired vasoreactivity in hypercholesterolaemia

A study was carried out in order to determine the feasibility and reproducibility of a direct plethysmographic assessment of unstimulated forearm arterial compliance (FAC) in hypercholesterolaemic and normocholesterolaemic subjects. Simultaneous recordings of forearm pulse volume and blood pressure over the whole cardiac cycle are used to establish the pulse volume-blood pressure relationship. FAC was measured on-line by computing the ratio of dV/dP. The area under the curve (FAC(AUC)) of FAC/blood-pressure curve was determined in a standard range of blood pressure (70-130 mmHg). The method was validated by demonstrating its capacity to detect changes in FAC(AUC) induced by nitrate and by muscarinic stimuli. The results show a reduced FAC(AUC) in hypercholesterolaemic patients vs. controls (2.28 +/- 0.8 x 10(-3) vs. 4.12 +/- 1.06 x 10(-3) (mL 100 mL-1 forearm mmHg-1) mmHg; P = 0.0001). The method appears to be highly sensitive to nitrate and muscarinic stimuli. The new technique provides a potentially useful tool to detect and monitor in vivo, without stimulating arterial dilatation, e.g. by acetylcholine infusion, the functional arterial changes in subjects with a major risk factor for arterial disease as well as the effects of dietary/drug treatments.

Therapy with HMG CoA reductase inhibitors: characteristics of the long-term permanence of hypocholesterolemic activity

Treatment with hydroxymethylglutaryl coenzyme A (HMG CoA) reductase inhibitors has gained considerable success in the management of hypercholesterolemia. A large number of studies have shown the efficacy of these drugs in lowering plasma total and low density lipoprotein (LDL) cholesterol levels, but there have been less studies evaluating their effectiveness in standard clinical practice, particularly relating to the maintenance of hypocholesterolemic activity. In the present study, the long-term effectiveness of HMG CoA reductase inhibitors has been tested in 177 patients with familial hypercholesterolemia (FH) who had been on statin therapy (simvastatin or pravastatin) for at least 12 months and up to 5 years or longer. The mean 'dose normalized' LDL cholesterol reduction in the whole group was around 20%. However, in spite of a generally good efficacy of both statins in lowering total and LDL cholesterol, a wide variety of responses, either after short- or long-term treatment, was noted. Individual responses were calculated and patients classified into three different groups: (a) responders, (b) non-responders, and (c) response losers. Of the 177 patients, 4% did not respond to treatment and a further 10% showed an initial unsatisfactory response (LDL cholesterol reduction < or = 10%). Another 10% experienced a progressive loss of response over time. There appeared to be little difference between the two treatments in the long-term efficacy and no predictive index could be established. Treatment with HMG CoA reductase inhibitors is generally effective and well tolerated, but a non-negligible number of patients may show a primary non-response or a progressive loss of response.

Effect of gemfibrozil treatment in hypercholesterolemia on low density lipoprotein (LDL) subclass distribution and LDL-cell interaction

Gemfibrozil, a widely used fibric acid derivative, corrects hypercholesterolemia in a non-negligible fraction of patients. To investigate the mechanism of the cholesterol-lowering activity of fibric acids, a study was performed in 12 type IIa hyperlipidemic patients treated with gemfibrozil for 12 weeks. Changes in low density lipoprotein (LDL) structure and composition, agonist capacity of LDL against the LDL-receptor in human skin fibroblasts, LDL-receptor activity in mononuclear cells, lecithin:cholesterol acyltransferase (LCAT) and cholesterol ester transfer protein (CETP) activity, were evaluated. Plasma total and LDL cholesterol levels decreased by 17% and 20% after 12 weeks of treatment, the reduction being directly correlated with the baseline levels (r = 0.75 and 0.78, respectively). The mean LDL diameter increased significantly, from 25.5 to 26.1 nm, while the relative content of small LDL particles (< 25.1 nm) increased from 23.4% to 32.8% of total LDL. Neither the apolipoprotein (apo) B secondary structure nor the affinity of LDL for the LDL-receptor of fibroblasts were affected. The LDL-receptor activity in patients' mononuclear cells increased 3-fold, the rise being unrelated to the plasma cholesterol reduction. LCAT activity did not change, while CETP activity was reduced by 25% (P = 0.13) after treatment. These findings indicate that gemfibrozil causes significant changes in LDL structure that do not, however, affect the LDL interaction with peripheral cells.

Microsomal enzyme inducers raise plasma high-density lipoprotein cholesterol levels in healthy control subjects but not in patients with primary hypoalphalipoproteinemia

In this study we compared the ability of phenytoin, a microsomal enzyme inducer, to raise plasma high-density lipoprotein (HDL) levels in normolipidemic subjects and patients with primary hypoalphalipoproteinemia. In healthy control subjects, phenytoin caused a dose-dependent increase of plasma HDL, HDL2, and HDL3 cholesterol levels, up to 40% to 50%. Minor changes were recorded in the plasma concentrations of apolipoprotein (apo) A-I and apo A-II; the plasma level of the cholesteryl ester transfer protein (CETP) decreased by 42%. In contrast, none of the patients with hypoalphalipoproteinemia had changes in plasma HDL, HDL2, or HDL3 cholesterol, apo A-I, apo A-II, or CETP levels. These findings indicate that microsomal enzyme inducers are unsuitable to increase plasma HDL levels in high-risk patients with primary hypoalphalipoproteinemia, and they disclose a new mechanism, that is, decreased CETP-mediated transfer of cholesterol out of HDL, for the HDL-raising effect of microsomal enzyme inducers in healthy individuals.

Prolonged inhibition of platelet aggregation after n-3 fatty acid ethyl ester ingestion by healthy volunteers

This study addressed two questions: 1) whether a relatively low dose of n-3 fatty acid ethyl esters (n-3 FAs) administered to healthy volunteers for a prolonged period of time would exert beneficial effects on plasma lipids, platelet function, and thromboxane biosynthesis; and 2) whether a short-term loading treatment (6 wk) with 6 g n-3 FAs/d followed by 12 wk with 3 g/d results in more pronounced effects. After 6 wk treatment a reduction of plasma triglyceride concentration and an accumulation of EPA and DHA in plasma were observed. A longer period of treatment with n-3 FAs was necessary to affect platelet aggregation and thromboxane A2 biosynthesis. At 12 and 18 wk, platelet aggregation, thromboxane A2 formation, and the excretion of thromboxane metabolites in urine were reduced, particularly in subjects who received 6 g n-3 FAs/d during the initial 6 wk. After treatment ended, triglyceride and thromboxane A2 biosynthesis returned to baseline values within 4 wk, whereas platelet aggregation remained impaired for > or = 14 wk. The longlasting impairment in platelet aggregation was accompanied by the retention of n-3 FAs in platelet phospholipids.

Pravastatin effectively lowers LDL cholesterol in familial combined hyperlipidemia without changing LDL subclass pattern

Familial combined hyperlipidemia (FCHL) is the most common genetic lipid disorder among young survivors of myocardial infarction. Elevations of plasma total and low-density lipoprotein (LDL) cholesterol and the prevalence of small, dense LDL particles are both involved in the high coronary risk of FCHL patients. We investigated the ability of pravastatin to favorably correct plasma lipid and lipoprotein levels and LDL structure in FCHL patients. Twelve patients with FCHL, documented by studies of first-degree relatives, received pravastatin (40 mg/d) for 12 weeks. Pravastatin significantly lowered plasma total and LDL cholesterol levels by 21% and 32%, respectively. Triglyceride levels did not change, and apolipoprotein B (apoB) concentrations decreased by 9% (P = NS). High-density lipoprotein (HDL) cholesterol increased by 6% because of a significant 73% rise of HDL2 cholesterol. LDL were smaller (diameter, 24.5 +/- 0.5 nm), less buoyant, and apoB-rich (cholesteryl ester-apoB ratio, 1.64 +/- 0.46) in the selected patients compared with patients with familial hypercholesterolemia or healthy control subjects. LDL became even smaller (23.8 +/- 0.6 nm) and richer in apoB (cholesteryl ester-apoB ratio, 1.27 +/- 0.52) after pravastatin treatment. Although pravastatin favorably altered plasma lipid and lipoprotein levels in FCHL patients, the abnormal LDL particle distribution and composition were not affected. Because of the apparent resistance of the small, dense LDL to drug-induced modifications, a maximal lipid-lowering effect is needed to reduce coronary risk in FCHL patients.

Lipoprotein structure in male subjects during in vivo lipolysis: effect of an anti-lipolytic treatment with acipimox

Plasma free fatty acid (FFA) levels were raised in healthy volunteers by the administration of a fatty meal and epinephrine infusion (0.15 mg/kg per min), to test the hypothesis that enhanced lipolysis might lead to changes in lipoprotein distribution and to the formation of lipoprotein complexes, also impairing the interconversion of high density lipoproteins (HDL). The study was carried out in double-blind conditions in volunteers pre-treated with either placebo or with acipimox, a nicotinic acid analogue with a long-lasting activity. Lipolysis was effectively induced; the treatment with acipimox prevented the rise of free fatty acids (FFA), and it also blunted the triglyceride (TG) increase occurring during the test. Whereas the mean low density lipoprotein (LDL) particle size did not change, the HDL particle distribution showed a progressive shift to smaller particles, both after placebo and after acipimox, the changes in size being maximal 3-7 h after the meal. Evaluation of HDL interconversion in plasma samples incubated at 37 degrees C for 6 h showed the expected accumulation of HDL2a particles, with a parallel decrease of HDL3a; however, this conversion was not affected by the presence of elevated FFA levels and no difference was noted in subjects taking either placebo or acipimox. These clinical data fail to confirm the hypothesis that enhanced lipolysis may lead to dramatic changes in plasma lipoprotein distribution and/or in aggregation or fusion of lipoprotein particles, as reported from in vitro experiments. This study, however, successfully achieved a useful model of exaggerated lipolysis and confirmed the important activity of a low dose nicotinic acid analogue in inhibiting lipolysis.

Plasma triglycerides and lipoprotein(a): inverse relationship in a hyperlipidemic Italian population

The relationship between plasma lipoprotein(a) (Lp(a)) levels and other clinical/biochemical variables was investigated in 1200 consecutive hyperlipidemic patients. Plasma Lp(a) concentrations were measured by a sandwich-ELISA method, while the patients were either on diet or diet plus lipid-lowering drugs; 38% of them had a plasma Lp(a) level > 30 mg/dl. The median plasma Lp(a) concentration and the frequency of Lp(a) > 30 mg/dl were significantly lower in individuals with severe hypertriglyceridemia vs. hypercholesterolemics (HC) or mixed hyperlipidemics (M-HLP), but similar to normolipidemic healthy controls. Patients with isolated moderate hypertriglyceridemia had Lp(a) levels intermediate between HC and M-HLP subjects. The in vitro addition of triglyceride-rich lipoproteins to normotriglyceridemic plasma did not affect the Lp(a) measurement. Plasma Lp(a) concentrations in the whole hyperlipidemic population correlated negatively with triglycerides and positively with total cholesterol, HDL-cholesterol and age, being unrelated to either body mass index or lipid-lowering treatment. In HC patients, the presence of tendon xanthomas was associated with twofold higher Lp(a) levels. These findings argue for a regulatory role of triglycerides on plasma Lp(a) levels in hyperlipidemic patients.

Increased postprandial lipemia in Apo A-IMilano carriers

Plasma lipid/lipoprotein changes were monitored after a fat load (65 g fat per square meter body surface area) in six carriers of the apolipoprotein A-IMilano (A-IM) variant and six age- and sex-matched control subjects. The magnitude of postprandial lipemia, calculated as the area under the curve (AUC) described by plasma triglyceride (TG) level versus time, was threefold higher in the A-IM carriers; however, after correction for the different baseline TG levels, it was similar to control subjects. Moreover, the magnitude of postprandial lipemia was positively correlated with baseline TG in both A-IM carriers (r = 0.77) and control subjects (r = 0.80), indicating that fasting TGs are a major determinant of postprandial response in all subjects. Postprandial lipemia was also inversely correlated with high density lipoprotein (HDL) and HDL2 cholesterol in both groups (A-IM, r = -0.81 and -0.79; control subjects, r = -0.87 and -0.94). Different from those in control subjects, the plasma apo A-I levels in the A-IM carriers decreased progressively while apo B increased up to 4 hours but decreased thereafter. Postprandial rises of low density lipoprotein TG but not of HDL-TG AUC were significantly higher in the A-IM carriers, even after normalization for the different fasting concentrations. These data show that the low plasma HDL levels of A-IM carriers, which are secondary to a primary structural alteration of the major HDL apolipoprotein, are associated with elevated fasting and postprandial TG levels and an anomalous postprandial redistribution of TG among lipoprotein classes.

Mechanisms of high-density lipoprotein reduction after probucol treatment: changes in plasma cholesterol esterification/transfer and lipase activities

Probucol treatment results in a significant reduction of plasma high-density lipoprotein (HDL) levels. Since the remodeling of HDL within the plasma compartment is a crucial determinant of HDL levels, the activities of several factors participating in the process, ie, lecithin:cholesterol acyltransferase (LCAT), cholesteryl ester transfer protein (CETP), and lipoprotein and hepatic lipases (LPL, HL), were evaluated in 15 hypercholesterolemic patients treated with probucol (1 g/d) for 8 weeks. Drug treatment was associated with significant reductions of HDL cholesterol ([HDL-C] -32%), HDL2-C (-65%), HDL3-C (-22%), apolipoprotein (apo)A-I (-27%), and apo A-II (-11%) levels and with the accumulation of small HDL in plasma. CETP activity increased by 48%, with minor changes in LCAT (-7%), LPL (+4%), and HL (-7%) activities. By linear regression analysis, CETP activity correlated inversely with HDL-C, HDL2-C, and apo A-I levels (r = -.63, -.52, and -.73, respectively) and with HDL particle size. In multivariate analysis, CETP activity was the strongest predictor of HDL-C levels, apo A-I levels, and HDL particle size. The hypothetical mechanism of probucol is a stimulation of CETP activity, resulting in the formation of triglyceride (TG)-enriched HDL. These are acted on by HL, leading to the accumulation of small HDL in plasma.

Prolonged retention of doubly labeled phosphatidylcholine in human plasma and erythrocytes after oral administration

The plasma kinetics of a preparation of dilinoleoyl phosphatidylcholine (DLPC) specifically labeled with 3H in the choline moiety and with 14C in the 2-fatty acid (FA) were evaluated in six healthy volunteers after oral administration. Retention of both isotopes in plasma exceeded expectations, with a half-life in the elimination phase of 172.2 h for 3H and 69.7 h for 14C. Up to 60 d after administration, there were still significant levels of radioactivity present in plasma. The relative stability of the [14C]FA label was demonstrated by the retention for more than 12 h of an isotope ratio close to that of the compound administered. The 14C label of DLPC remained in position-2, as assessed by cleavage of plasma phospholipids with phospholipase A2. The [3H]choline label showed an early incorporation into high density lipoproteins and subsequently into low density lipoproteins (LDL); conversely, the 14C radioactivity was rapidly incorporated into triacylglycerols that were mainly associated with very low density lipoproteins. Radioactivity measurements revealed that both isotopes remained the longest time in LDL. In red blood cell (RBC) lipids, [3H]choline radioactivity accumulated over time, with a plateau after 48 h, whereas FA radioactivity accumulated more rapidly and was followed by a progressive decay. Analysis of the isotope ratio in these cells suggested an early incorporation of lyso products followed by rapid transfer of FA from plasma. The RBC maintained considerable radioactivity for a prolonged time, thus acting as a possible reservoir for the DLPC administered.(ABSTRACT TRUNCATED AT 250 WORDS)

Bezafibrate lowers plasma lipids, fibrinogen and platelet aggregability in hypertriglyceridaemia

The effects of bezafibrate 400 mg/day (slow release formulation) on plasma lipids/lipoproteins and on selected haemostatic parameters were evaluated in a double blind cross-over study in patients with Type IIb and IV hyperlipoproteinaemia. Placebo treatment did not influence any of those parameters, but the drug significantly reduced plasma triglycerides (-45%) and VLDL cholesterol, as well as causing a 12% fall in total cholesterol and a 20% increase in HDL cholesterol. Apo AI levels were significantly increased following bezafibrate and Apo B was reduced by about 20%. In addition to changes in the plasma lipid profile, bezafibrate reduced the sensitivity of platelets to the aggregatory effect of collagen, with no effect on TXB2 production. Fibrinogen levels after bezafibrate treatment were significantly lowered, the effect being more marked in patients with hyperfibrinogenaemia. Bezafibrate did not influence the plasma fibrinolytic profile. It is concluded that bezafibrate, besides its beneficial effects on the plasma lipoprotein profile, can exert beneficial changes on specific haemostatic parameters.

Olive oil, corn oil, and n-3 fatty acids differently affect lipids, lipoproteins, platelets, and superoxide formation in type II hypercholesterolemia

To evaluate which dietary fat may provide the best response in terms of plasma lipids and lipoproteins and also of platelet aggregability and superoxide formation by white blood cells, 12 type II patients were randomly allocated to three different diets, which provided polyunsaturated fatty acids (corn oil), monounsaturated fatty acids (olive oil), and a supplementation of ethyl esters of n-3 fatty acids to a prudent diet. Olive oil and, more significantly, n-3 ethyl esters lowered total cholesterol best (-2.2% and -5.8%, respectively); the latter diet, as expected, also significantly lowered triglyceridemia (-21.4%). The corn-oil diet exerted a small, statistically significant reduction of high-density-lipoprotein cholesterol (HDL) (-4.3%), and it also lowered plasma total apo B concentrations (-3.8%). n-3 ethyl esters significantly raised both total (+3.1%) and particularly HDL2 cholesterol (+24%). Platelet reactivity was insignificantly reduced by the three regimens, but all three significantly reduced thrombin-stimulated formation of thromboxane B2. Finally, only the n-3 fatty acid supplementation significantly reduced O2- generation by adherent monocytes. Dietary unsaturated fatty acids are generally effective on the plasma lipid and lipoproteins in type II patients, but significant differences may be found between the three tested regimens.

Activity profile of gemfibrozil on the major plasma lipoprotein parameters

Gemfibrozil (G) is a widely used and highly effective fibric acid derivative. It acts both on lipoprotein disorders characterized by hypertriglyceridemia, as well as in hyperchlolesterolemia. The results of two separate studies are summarized, in order to elucidate the differential activity profile of the drug on the major plasma lipoprotein parameters. In a group of hypertriglyceridemic patients (Study I) the major activity of G was on the VLDL cholesterol (C) and triglyceride levels (respectively -40.4 and -35.7%), associated with a marked increase of the HDL-C levels, in particular in the HDL3 subfraction. In addition, apolipoprotein B levels were significantly reduced (-12%) in all treated patients. In Study II, treatment with G in severe hypercholesterolemia was compared to that with pravastatin, a major hydroxymethylglutaryl coenzyme A reductase inhibitor. G, in these patients, markedly reduced both total (-21.6%) and LDL-cholesterol (-24.4%) levels. The increase of HDL-C was less marked than in type IV patients but G, similarly to pravastatin, induced a significant reduction of apolipoprotein B, together with an increase (+19.2%) of apolipoprotein AII levels. These findings indicate that the activity profile of G is wider than expected and that it may include a reduction of LDL levels in severely hypercholesterolemic patients. The mechanism of this latter change is difficult to establish, although it may also be related to an improved delipidation of LDL, resulting in a more efficient interaction with peripheral high affinity receptors.

Differential effect of unsaturated oils and butter on blood glucose and insulin response to carbohydrate in normal volunteers

Plasma glucose and insulin responses were monitored in normal volunteers after a standard carbohydrate meal with unsaturated oils (olive and corn oil, in identical volumes) or butter. Both unsaturated oils almost totally blunted the glycaemic response; butter, instead, only delayed the plasma glucose rise, without significantly changing the area under the curve. The insulin rise was essentially unaffected by the three experimental meals, only a slight delay in the peak being observed with no differences between unsaturated oils and butter. These findings support previous data indicating reduced glucose levels after prolonged administration of olive oil, and reduced glycaemic response, in the absence of clear-cut insulin changes, differentiates unsaturated oils from indigestible fibres; it may be linked to an altered polysaccharide handling at the intestinal level.

Omega-3 fatty acids selectively raise high-density lipoprotein 2 levels in healthy volunteers

The effects of omega-3 fatty acid supplementation on high-density lipoprotein (HDL) subfraction distribution and composition were evaluated in five healthy volunteers taking 2.8 g/d of eicosapentaenoic acid (EPA) and 1.7 g/d of docosahexaenoic acid (DHA) for 6 weeks. This supplementation resulted in marked changes of the plasma fatty acid composition. Plasma total cholesterol (TC), HDL-cholesterol (HDL-C), and triglyceride (TG) levels did not change. HDL2-C increased by 74%, with a concomitant 19% decrease of HDL3-C; the HDL2 to HDL3 mass ratio increased from 0.30 +/- 0.19 to 0.47 +/- 0.28. The increase of HDL2 was confirmed by nondenaturing polyacrylamide gradient gel electrophoretic separation of HDL subclasses, otherwise showing no change in HDL particle size. After omega-3 supplementation, both HDL2 and HDL3 became cholesteryl ester (CE)- and TG-enriched and free cholesterol (FC)- and phospholipid (PL)-depleted. The reported findings provide a useful adjunct to the antithrombotic potential of omega-3 fatty acids.

Efficacy of cholestyramine does not vary when taken before or during meals

Compliance to cholestyramine treatment, often unsatisfactory, may become further problematic because of the common indication that the resin should not be taken with meals. Since there is no convincing data on the validity of this therapeutic schedule, 10 type IIA hyperlipoproteinemic patients received cholestyramine either before or during the 3 major meals, according to a cross-over protocol. Plasma lipid levels were monitored after 4 and 6 weeks of each treatment schedule. The efficacy of the resin, in terms of total cholesterol (-16.5% together with food vs. -17.2% before food) and of low density lipoprotein cholesterol reduction (-22.8% with food vs. -23.1% before food) did not differ. The side effect profile was also not different between the two treatment protocols. These findings suggest that there are no significant interactions between food and the anion exchange resin and that the hypocholesterolemic effect does not depend upon a specific timing, supposedly close to the gallbladder contraction. They are particularly significant in view of the future availability of new resins in liquid form, suitable for intake during meals.

Predictability of low-density lipoprotein levels during apheretic treatment of hypercholesterolaemia

The efficiency and efficacy of low-density lipoprotein (LDL) apheresis performed with a dextran sulphate cellulose (DSC) regenerating unit were tested in five familial hypercholesterolaemic patients. LDL apheresis was repeated four times at both bi-weekly and weekly intervals, processing one plasma volume each time. The efficiency of the procedure (i.e., the extent of lipoprotein removal) was nearly identical with both schedules. Efficacy parameters, i.e., decreases of plasma total and LDL cholesterol (TC and LDL-C) and apo B, were highly correlated (r greater than 0.96) with preapheresis levels, allowing an accurate prediction of the absolute lipid removal in the single individual. Plasma triglycerides, high-density lipoprotein cholesterol, apo A-I and apo A-II recovered rather rapidly, reaching 91-96% of the pre-apheresis values in 48 hours; the recovery of TC, LDL-C and apo B was much slower, with a relatively rapid early phase (80% recovery after about 7 days) followed by a successive slower rise. This pattern was highly reproducible in the single patient, allowing the definition of a simple mathematical model for an accurate (error less than 20%) prediction of the individual process. Based on this model one can design the treatment schedule necessary to maintain lipid levels within the desired range in the single individual. The hypolipidaemic efficacy of DSC apheresis appears, otherwise, not to be dependent upon the procedure per se, but on other individual factors, e.g. the amount of removable lipoproteins and the rate of lipid recovery; both can be predicted with sufficient accuracy.

Comparison of the lipoprotein and hemostatic changes after a triphasic and a monophasic low dose oral contraceptive in premenopausal middle-aged women

Metabolic and hemostatic effects of 2 low dose oral contraceptives (OCs), a triphasic (ethinylestradiol + (-)-norgestrel) and a monophasic (ethinylestradiol + desogestrel) preparation, were compared in a cross-over trial in fertile women over 35 years of age. Both combinations moderately affected plasma lipids, with 17-24% increases of total triglyceridemia. Triglycerides accumulate in low density lipoproteins, thus suggesting the possible formation of an atherogenic lipoprotein particle. Only the monophasic preparation increased high density lipoprotein (HDL)-cholesterol levels significantly, with a rise in HDL3 mass and cholesterol. OC treatment led to slight changes in HDL2 and HDL3 structure, with a rise of the cholesteryl ester and triglyceride contents, indicative of a stimulated cholesterol esterification and reverse transport. Changes in the hemostatic indexes (fibrinogen, antithrombin III and protein C) were negligible. The new low dose OCs, even when prescribed to relatively older women, affect to a relatively small extent lipid/lipoprotein metabolism, with the exception of changes in the low density lipoprotein composition.

Influence of serum triglycerides on the HDL pattern in normal subjects and patients with coronary artery disease

The distribution and structure of high density lipoprotein (HDL) subfractions were examined by rate zonal ultracentrifugation in 200 consecutive subjects, 86 of whom showed a stable hypertriglyceridemia, 22 with coronary artery disease. Among the remaining 114 normotriglyceridemic subjects, 75 were healthy and 39 had coronary disease. The serum levels of the HDL2 subfraction were reduced by 22% in the 39 normotriglyceridemic coronary patients, and by 21% in the whole group of hypertriglyceridemic subjects. No difference in the HDL3 levels was found in any of the studied group. There was a clear negative correlation between HDL2 levels and triglyceridemia in the case of healthy people, not in coronary patients. By contrast, triglyceridemia was negatively correlated with the HDL3 flotation rate, both in healthy subjects and coronary patients at all triglyceride levels. Compositional data indicate that in hypertriglyceridemic subjects, HDL2 levels are reduced because of an enhanced transfer-exchanged process between the enlarged VLDL pool and HDL; in contrast, in coronary patients, a defective maturation of the HDL3 particle is the most likely underlying mechanism. Both in hypertriglyceridemic individuals, as well as in coronary patients, the HDL subfraction distribution is rather similar and drastically different from that of normotriglyceridemic healthy subjects. The mechanisms of the two conditions are probably different and, whereas a low concentration of HDL2 is definitely a major risk factor for normotriglyceridemic individuals, in the case of hypertriglyceridemics other factors may come into play in the final determination of the coronary risk.

Apolipoprotein AIMilano. Disulfide-linked dimers increase high density lipoprotein stability and hinder particle interconversion in carrier plasma

The in vitro metabolism of high density lipoproteins (HDL) in carriers of the apolipoprotein AIMilano (apoAIM) mutant was investigated during incubation of whole plasma and isolated lipoprotein fractions. A reduced cholesterol esterification (16.5 versus 25.0% for controls) and a decreased exchange of lipids between HDL and lower density lipoproteins was observed during incubation (6 h at 37 degrees C) of AIM plasma. Control HDL3 were converted to larger, faster-floating HDL particles, whereas only a fraction of AIM HDL3 followed the same pathway. Incubations were also carried out by mixing HDL3 from controls and AIM carriers with a lipoprotein-depleted plasma fraction in the presence of triglyceride-rich particles isolated from Intralipid. AIM HDL3 again showed a reduced capacity for lipid exchange; some HDL3 particles followed a "normal" conversion to faster-floating, larger HDL, whereas the small AIM HDL3 were not modified, indicating that AIM HDL3 are a mixture of metabolically functional and nonfunctional particles. Following transformation of the apoAIM homo- and heterodimers into their normal counterparts, i.e. monomeric apoAI and -AII, by reduction and carboxamidomethylation of AIM HDL3, the modified HDL3 behave like control HDL3 during incubation with lipoprotein-depleted plasma and triglyceride-rich particles. The presence of AIM dimers is most likely responsible for the increased HDL3 stability in the AIM carriers, indicating that apolipoprotein composition plays a major role in HDL particle interconversion.

Plasma lipoprotein changes after treatment with pravastatin and gemfibrozil in patients with familial hypercholesterolemia

The ability of pravastatin, a new hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, to lower plasma lipid levels and modify lipoprotein patterns was compared with that of gemfibrozil in 18 patients with familial hypercholesterolemia who participated in a 16-week, double-blind, parallel trial. Pravastatin proved better than gemfibrozil in lowering total and low-density lipoprotein (LDL) cholesterolemia: -23.6% and -28.2% versus -18.1% and -21.4%, respectively. A significant positive correlation was found between the starting level of serum cholesterol (both total and LDL) and the gemfibrozil-induced reduction (r = 0.72 and 0.69), whereas the hypocholesterolemic effect of pravastatin was apparently independent from pretreatment levels (r = 0.32 and 0.10). Apolipoprotein B concentrations were lowered by 25.4% (pravastatin) and 22.0% (gemfibrozil). Pravastatin and gemfibrozil reduced triglyceride levels by 13.9% and 49.4%, respectively. Both drugs increased the level of high density lipoprotein (HDL) cholesterol, but this change was significant only with gemfibrozil (p less than 0.05). The HDL subfraction structure and distribution were not modified by pravastatin treatment. Gemfibrozil, in contrast, increased HDL3 cholesterol level by 9% because of an enrichment of HDL3 particles in both free cholesterol and cholesteryl esters and lowered the flotation rate of HDL3 (p less than 0.05). LDL particles became smaller after gemfibrozil treatment (diameter: 25.4 +/- 0.3 nm vs 26.1 +/- 0.4 nm, p less than 0.01) and were not modified by pravastatin. This comparison shows a more pronounced efficacy of the HMG CoA reductase inhibitor on total and LDL cholesterol levels, also indicating that pravastatin acts by a single major mechanism, reducing the number of circulating LDL particles. Gemfibrozil may exert additional activities, possibly consequent to the stimulation of very low density lipoprotein catabolism.

Mechanisms of HDL reduction after probucol. Changes in HDL subfractions and increased reverse cholesteryl ester transfer

Treatment with probucol, a widely used lipid-lowering agent, is associated with a significant reduction of high density lipoprotein (HDL) cholesterol levels, but with an apparently improved removal of cholesteryl esters from tissues (e.g., from tendon xanthomas). The effects of probucol (500 mg twice daily) on HDL subfraction distribution and cholesteryl ester transfer activity were tested in 12 patients with stable type II hyperlipidemia [low density lipoprotein (LDL) cholesterol greater than 180 mg/dl] after a placebo-controlled cross-over trial. Probucol significantly lowered total cholesterol (-13.8%), LDL cholesterol (-9.1%), and HDL cholesterol (-30%). By rate zonal ultracentrifugation, a marked reduction of HDL2 cholesterol (-68%) was shown, whereas changes in HDL3 were less significant (-21%). These findings were confirmed by polyacrylamide gradient gel electrophoresis, typically showing a reduction or disappearance of HDL2b particles and the prevalence of particles in the HDL3a range. Cholesteryl ester transfer from HDL to lower density lipoproteins was significantly increased (30%) in all patients. These findings suggest that, in addition to the well-documented in vitro changes (prevention of LDL peroxidation and macrophage uptake), probucol characteristically modifies HDL particle distribution in vivo, and is associated with a significant increase of cholesteryl ester transfer activity.

Lipid effects of celiprolol, a new cardioselective beta-blocker, versus propranolol

The metabolic effects of celiprolol, a new beta-adrenoceptor blocking agent with intrinsic sympathomimetic activity and alpha 2-blocking properties, were evaluated in a series of patients with hypertension, both with and without hyperlipidemia. Propranolol was tested as the reference drug in a randomized double-blind trial. Of the 35 patients of both sexes who completed the study, 17 were hyperlipidemic (low-density lipoprotein cholesterol greater than or equal to 170 mg/dl) and 18 were normolipidemic. Both drugs exerted a similar hypotensive effect after gradual dose adjustment; however, propranolol reduced heart rate to a higher extent (-20.5%) than celiprolol (-7.7%). Propranolol determined a significant rise of total and very low-density lipoprotein (VLDL) associated triglyceridemia, whereas high-density lipoprotein cholesterol (HDL cholesterol) levels and the total cholesterol/HDL cholesterol ratios were significantly depressed, particularly in hyperlipidemic patients. Celiprolol, in contrast, slightly decreased triglyceridemia (significantly in the hyperlipidemic group at week 12) and caused a 5% increase of the HDL cholesterol levels. The total cholesterol/HDL cholesterol ratio was reduced by celiprolol at week 16 in both hyperlipidemic and normolipidemic patients. The effects of the two beta-adrenoceptor blockers on HDL cholesterol and triglyceride levels differed significantly after 12 and 16 weeks of treatment, which confirm the divergent metabolic effects of the two agents.

Apheretic treatment of severe familial hypercholesterolemia: comparison of dextran sulfate cellulose and double membrane filtration methods for low density lipoprotein removal

The two more widely available techniques for the extracorporeal removal of low density lipoproteins (LDL), dextran sulfate cellulose column and double membrane filtration, were comparatively tested in severe familial hypercholesterolemic patients, both acutely and during a continued 3-month treatment. The selective dextran sulfate procedure removed close to 60% of LDL and 16% of high density lipoproteins (HDL) upon each apheresis, vs. 42% and 32%, respectively, in the case of the semi-selective double membrane filtration. Upon long term biweekly treatments, LDL-cholesterol (LDL-C) decreased, with the selective procedure, from a pre-treatment level of 406.0 +/- 40.7 mg/dl to a value fluctuating between 295.4 +/- 33.8 mg/dl and 116.9 +/- 22.0 mg/dl (highest vs. lowest levels) whereas, in the case of double membrane filtration, LDL-C levels ranged between 334.8 +/- 39.8 mg/dl and 192.3 +/- 49.9 mg/dl. HDL-cholesterol levels were somewhat raised, to a higher extent with dextran sulfate apheresis. The LDL/HDL-cholesterol "atherogenic ratio", decreased from a pre-treatment value of 10.27 +/- 3.04 to values ranging between 3.61 and 6.82 with dextran sulfate and between 6.70 and 7.68 with double membrane plasmapheresis.

Effects of gemfibrozil on plasma lipoprotein-apolipoprotein distribution and platelet reactivity in patients with hypertriglyceridemia

The effects of gemfibrozil on plasma lipoprotein distribution and composition and on platelet function were investigated in 11 patients with stable hypertriglyceridemia, six belonging to Fredrickson type IIb and five to type IV. Gemfibrozil (600 mg twice a day) significantly reduced total and very low density lipoprotein (VLDL)--associated triglyceridemia (respectively-32.4% and -40.4%, after 6 weeks of treatment). No significant variations were noted in the lipid components of low-density lipoproteins; by contrast, a marked increase (18%) was detected in high-density lipoprotein (HDL)--associated cholesterol. Comparison of the two patient groups (type IIb and type IV) showed that those with type IIb had both a more significant reduction of triglyceridemia and a more marked increase of HDL-cholesterol. Apolipoprotein B levels were reduced in both groups (-12%) with no change in apolipoprotein AI. The cholesterol content in the HDL subfractions, separated by rate zonal ultracentrifugation, was raised in HDL3 (18%) and in HDL2 (14%). Both particles also showed significant increases of the cholesterol/protein and the cholesterol/phospholipid ratios. A non-statistically significant decrease in collagen-induced aggregation and in the release of thromboxane B2 was noted after treatment. These findings suggest that, similar to what was recently reported in normal individuals and in laboratory animals, the probable mode of action of gemfibrozil is in reducing the secretion of atherogenic lipoproteins, particularly VLDL, while stimulating the production of small HDL particles.

Controlled evaluation of fat intake in the Mediterranean diet: comparative activities of olive oil and corn oil on plasma lipids and platelets in high-risk patients

Activities of low-fat diets with olive oil or corn oil on lipids and platelets were studied in 23 middle-aged patients with high atherosclerosis risk for 8 wk. The olive oil diet had a polyunsaturated-saturated ratio of 0.33 vs 1.28 for the corn oil diet. Plasma total cholesterol was reduced with corn oil, but high-density lipoprotein cholesterol levels were lower with corn oil and unchanged or raised by olive. Plasma apolipoprotein B levels were equally reduced by both diets; apolipoprotein AI and the apo AI:B ratio rose only with olive oil. Plasma-glucose levels were lowered significantly with olive oil. Changes in platelet function were characterized by a reduced sensitivity to arachidonic acid (particularly with corn oil) and to collagen (particularly with olive). An olive oil diet with a moderate fat intake (about 30% of total calories) leads to favorable plasma lipoprotein and platelet changes.

Apolipoprotein AIMilano. Accelerated binding and dissociation from lipids of a human apolipoprotein variant

The lipid binding properties of apolipoprotein (apo) AIMilano, a molecular variant of human apolipoprotein AI, characterized by the Arg173----Cys substitution, was investigated by the use of dimyristoylphosphatidylcholine liposomes. Both the variant AIMilano and normal AI are incorporated to the same extent in stable complexes isolated by gel filtration, showing similar dimensions and stoichiometries. A higher affinity of apo-AIMilano for dimyristoylphosphatidylcholine is suggested by the faster association rate of the variant apoprotein compared to normal AI; similarly, apo-AIMilano is more readily displaced by guanidine hydrochloride from the isolated dimyristoylphosphatidylcholine-apoprotein complexes. When the secondary structure of apo-AIMilano was investigated by spectrofluoroscopy and circular dichroism, a higher fluorescence peak wavelength and a lower alpha-helical content were detected in the variant apoprotein compared to normal AI. The substitution Arg173----Cys in the AIMilano dramatically alters the amphipathic nature of the modified alpha-helical fragment of apoprotein AI. The association rate with lipids is accelerated by an increased exposure of hydrophobic residues. The reduced stability of the lipid-apoprotein particles is possibly mediated by a reduction in the number of helical segments involved in lipid association. The high flexibility of the AIMilano apolipoprotein in the interaction with lipids may explain its accelerated catabolism and the possibly improved uptake capacities for tissue lipids.