Temporal optimization of exercise to lower fasting glucose levels.

Exercise stimulates glucose uptake and increases insulin sensitivity acutely. Temporally optimizing exercise timing may minimize the nocturnal rise in glucose levels. This study examined the effect of exercise timing on evening and overnight glucose concentrations in individuals who were non-obese with normal fasting glucose levels (Non-Ob; n = 18) and individuals with obesity (OB) with impaired fasting glucose levels (OB+IFG) and without (n = 16 and n = 18, respectively). Subjects were studied on three occasions (no exercise (NOEX)), morning exercise (AMEX; 0700 h) and evening exercise (PMEX; 2000 h). The evening meal was provided (1800 h) and blood samples were taken from 1740 to 0700 h and morning endogenous glucose production (EGP) was measured. Glucose and insulin concentrations increased with the dinner meal with peak concentrations being higher in OB+IFG than in OB and Non-Ob (P = 0.04). In OB+IFG, evening glucose concentrations rose above baseline levels at about 2300 h, with the glucose concentrations staying somewhat lower with AMEX and PMEX until ∼0500 h than with NOEX. In OB+IFG, insulin concentrations decreased following the dinner meal and waned throughout the night, despite the rising glucose concentrations. In the OB and Non-Ob individuals following the dinner meal, no increase in glucose concentrations occurred in the evening period and insulin levels mirrored this. No difference was observed in the morning fasting glucose levels between study days or between groups. Regardless of time of day, exercise delays the evening rise in glucose concentrations in adults with OB+IFG but does not lower morning fasting glucose levels or improve the synchrony between glucose and insulin concentrations. KEY POINTS: Insulin resistance and type 2 diabetes have been linked to disturbances of the core clock, and glucose tolerance demonstrates a diurnal rhythm in healthy humans with better glucose tolerance in the morning than in the afternoon and evening. Skeletal muscle is a primary site for insulin resistance in people with impaired glucose tolerance. In individuals with obesity and impaired fasting glucose levels (OB+IFG), following a dinner meal, glucose concentrations started to rise and continues throughout the night, resulting in elevated glucose levels, while concomitantly, insulin levels are waning. Exercise, regardless of the time of day, suppressed the rise in glucose levels in OB+IFG for many hours during the night but did not lower morning fasting glucose levels. Morning exercise was not quite as effective as evening exercise.

Population genetic analysis of Tomato spotted wilt virus on peanut in North Carolina and Virginia.

Exploring the genetic diversity and evolutionary history of plant viruses is critical to understanding their ecology and epidemiology. In this study, maximum-likelihood and population genetics-based methods were used to investigate the population structure, genetic diversity, and sources of genetic variation in field isolates of Tomato spotted wilt virus (TSWV) from peanut in North Carolina and Virginia. Selected regions of the nucleocapsid, movement, and RNA-dependent RNA polymerase genes were amplified and sequenced to identify haplotypes and infer genetic relationships between isolates of TSWV with heuristic methods. The haplotype structure of each locus consisted of 1 or 2 predominant haplotypes and >100 haplotypes represented by a single isolate. No specific haplotypes were associated with geographic area, peanut cultivar, or year of isolation. The population was panmictic at the regional level and high levels of genetic diversity were observed among isolates. There was evidence for positive selection on single amino acids in each gene on a background of predominant purifying selection acting upon each locus. The results of compatibility analyses and the persistence of specific gene sequences in isolates collected over three field seasons suggest that recombination was occurring in the population. Estimates of the population mutation rate suggest that mutation has had a significant effect on the shaping of this population and, together with purifying selection, these forces have been the predominant evolutionary forces influencing the TSWV population in peanut in North Carolina and Virginia.

An Assessment of the Genetic Diversity in a Field Population of Phytophthora nicotianae with a Changing Race Structure.

One hundred fifty-three isolates of Phytophthora nicotianae that were collected over a 4-year period from a single field were subjected to amplified fragment length polymorphism (AFLP) analysis to investigate the effect of different types of resistance in tobacco (Nicotiana tabacum) on genetic diversity in the pathogen population. No race 1 isolates were detected in the field prior to initiating the study, but the race was present in multiple plots by the end of the 4-year period. There were 102 race 0 isolates and 51 race 1 isolates characterized. Seventy-six of the 153 isolates had a unique AFLP profile, whereas the remaining 77 isolates were represented by 27 AFLP profiles shared by at least two isolates. Isolates of both races were found in both the unique and shared AFLP profile groups. Twenty-three of the AFLP profiles were detected in multiple years, indicating a clonal component to the pathogen population. Race 1 isolates that were detected over multiple years were always obtained from the same plot. No race 1 profile was found in more than one plot, confirming the hypothesis that the multiple occurrences of the race throughout the field were the result of independent events and not pathogen spread. Three identical race 0 AFLP profiles occurred in noncontiguous plots, and in each case, the plots contained the same partially resistant variety. Cluster analysis provided a high level of bootstrap support for 41 isolates in 19 clusters that grouped primarily by race and rotation treatment. Estimates of genetic diversity ranged from 0.365 to 0.831 and varied depending on tobacco cultivar planted and race. When averaged over all treatments, diversity in race 1 isolates was lower than in race 0 isolates at the end of each season. Deployment of single-gene resistance initially decreased genetic diversity of the population, but the diversity increased each year, indicating the pathogen was adapting to the host genotypes deployed in the field.

Effects of a low-fat, high-carbohydrate diet on VLDL-triglyceride assembly, production, and clearance.

Low-fat, high-carbohydrate (LF/HC) diets commonly elevate plasma triglyceride (TG) concentrations, but the kinetic mechanisms responsible for this effect remain uncertain. Subjects with low TG (normolipidemic [NL]) and those with moderately elevated TG (hypertriglyceridemic [HTG]) were studied on both a control and an LF/HC diet. We measured VLDL particle and TG transport rates, plasma nonesterified fatty acid (NEFA) flux, and sources of fatty acids used for the assembly of VLDL-TG. The LF/HC diet resulted in a 60% elevation in TG, a 37% reduction in VLDL-TG clearance, and an 18% reduction in whole-body fat oxidation, but no significant change in VLDL-apo B or VLDL-TG secretion rates. Significant elevations in fasting apo B-48 concentrations were observed on the LF/HC in HTG subjects. In both groups, fasting de novo lipogenesis was low regardless of diet. The NEFA pool contributed the great majority of fatty acids to VLDL-TG in NL subjects on both diets, whereas in HTG subjects, the contribution of NEFA was somewhat lower overall and was reduced further in individuals on the LF/HC diet. Between 13% and 29% of VLDL-TG fatty acids remained unaccounted for by the sum of de novo lipogenesis and plasma NEFA input in HTG subjects. We conclude that (a) whole-food LF/HC diets reduce VLDL-TG clearance and do not increase VLDL-TG secretion or de novo lipogenesis; (b) sources of fatty acids for assembly of VLDL-TG differ between HTG and NL subjects and are further affected by diet composition; (c) the presence of chylomicron remnants in the fasting state on LF/HC diets may contribute to elevated TG levels by competing for VLDL-TG lipolysis and by providing a source of fatty acids for hepatic VLDL-TG synthesis; and (d) the assembly, production, and clearance of elevated plasma VLDL-TG in response to LF/HC diets therefore differ from those for elevated TG on higher-fat diets.

First Report of Sweet potato chlorotic stunt virus, a Component of Sweetpotato Virus Disease, in North Carolina.

Sweet potato chlorotic stunt virus (SPCSV) is the whitefly-transmitted component of the sweet potato virus disease (SPVD), a devastating disease originally described in Africa (4). Two isolates designated as G-01 and T-03 were obtained in North Carolina in July 2001 and October 2003, respectively, from plants of cv. Beauregard exhibiting symptoms typical of SPVD, including stunting, leaf narrowing and distortion, vein clearing, and chlorotic mosaic. Sap extract from symptomatic plants tested positive for SPCSV by nitrocellulose immuno-dot blot, using monoclonal antibodies specific for SPCSV obtained from the International Potato Center. Total RNA was extracted from 100 mg of symptomatic leaf tissue by using the PureLink Total RNA Purification System Kit from Invitrogen (Carlsbad, CA) with a minor modification (adding 2% PVP-40 and 1% 2-mercaptoethanol to the extraction buffer) (1). Results were confirmed by reverse transcription (RT)-PCR using primers CP1 and CP3 and HSP70-A/HSP70-B (2), corresponding to the capsid protein and 'heat shock' protein genes, respectively. HSP70 amplicons were cloned using the TOPO TA Cloning Kit (Invitrogen) and sequenced. At the nucleotide level, viral sequences from clones from both isolates were an average 99.4% similar to West Africa and 77.9% to East Africa sequences of SPCSV from Genbank (1). Although the isolates were collected from different fields, viral sequences generated from clones for T-03 and G-01 differed by only six nucleotides and were identical at the amino acid level. The neighbor-joining phylogenetic tree constructed using the HSP70 gene fragment (39 nt) delineated two major clusters with two subpopulations each: Cluster 1, "East Africa", consisted of East Africa and Peru subpopulations; Cluster 2, "West Africa", consisted of Argentina-Brazil and USA-West Africa subpopulations (1). In addition, SPCSV isolates from East Africa and West Africa clusters were sufficiently distant phylogenetically to suggest that they may correspond to two different criniviruses, with an average similarity between the populations of 78.14% and an average within the populations above 89%. Hudson's tests confirmed the presence of genetically distinct SPCSV groups with high statistical significance (1). Two groups (Peru and East Africa) were differentiated in the East Africa cluster, and three groups (Argentina-Brazil, USA, and West Africa) were differentiated in the West Africa cluster, suggesting that the USA population is not a recent introduction. Although SPCSV was previously reported in the United States, the source was a single accession of cv. White Bunch from the USDA Sweetpotato Germplasm Repository (3). Sweet potato feathery mottle virus (SPFMV) (family Potyviridae, genus Potyvirus), the other component of SPVD, was also detected in both cultivars. To our knowledge, this is the first report of SPCSV in sweetpotato fields in the United States. References: (1) J. A. Abad et al. Phytopathology (Abstr.) 96(suppl.):S1, 2006. (2) T. Alicai et al. Plant Pathol. 48:718, 1999. (3) G. Pio-Ribeiro et al. Plant Dis. 80:551, 1996. (4) G. A. Schaefer and E. R. Terry. Phytopathology 66:642, 1977.

Dependence of plasma alpha-tocopherol flux on very low-density triglyceride clearance in humans.

To evaluate the effect of dietary fat-induced alterations in triglyceride (TG) metabolism on plasma and very low-density lipoprotein (VLDL)-alpha-tocopherol, nine healthy males (mean +/- SEM, age: 36 +/- 3 years, BMI: 24.7 +/- 1.1) consumed a 35%-fat diet (control) for one week followed by a 15% low-fat, high-carbohydrate diet for 5 weeks. After each dietary phase, the subjects ingested an evening meal along with a 50 mg capsule of (2)H(6)-RRR-alpha-tocopheryl acetate; blood samples were drawn over a 24 h period while the subjects remained fasted. Low-fat feeding increased fasting plasma TG concentrations by 53% (116 +/- 27 to 178 +/- 32, mg/dl, p < 0.0001) primarily by reducing VLDL-TG clearance. Total plasma alpha-tocopherol concentrations (labeled + unlabeled) were unchanged (25.8 +/- 2.3 vs. 26.4 +/- 3.0 nmol/ml plasma) and no differences between the diets were observed for plasma (2)H(6)-alpha-tocopherol concentration (4.8 +/- 0.6 nmol/ml, for both diets) or enrichments (18.1 +/- 1.8% average for both diets). However, low-fat feeding significantly increased the amount of alpha-tocopherol in the VLDL fraction (43%, p = 0.04) in concert with elevations in VLDL-apoB and TG. The alpha-tocopherol and TG content of VLDL varied in parallel in individual subjects and fractional replacement rates and clearance of alpha-tocopherol and TG in VLDL were closely correlated. Kinetic parameters were decreased by 32-39% from high-fat to low-fat. These data suggest that vitamin E bioavailability is similar between a 15 and 35% fat diet, with a redistribution of alpha-tocopherol in lipoproteins occurring during low-fat feeding (increased in the VLDL fraction, reduced in the other lipoproteins), and transfer of alpha-tocopherol from VLDL depends upon TG removal from the particle, consistent with previous observations in vitro and in animal studies.

Carbohydrate-induced hypertriacylglycerolemia: historical perspective and review of biological mechanisms.

Current trends in health promotion emphasize the importance of reducing dietary fat intake. However, as dietary fat is reduced, the dietary carbohydrate content typically rises and the desired reduction in plasma cholesterol concentrations is frequently accompanied by an elevation of plasma triacylglycerol. We review the phenomenon of carbohydrate-induced hypertriacylglycerolemia, the health effects of which are among the most controversial and important issues in public health nutrition today. We first focus on how seminal observations made in the late 1950s and early 1960s became the basis for subsequent important research questions and areas of scientific study. The second focus of this paper is on the current knowledge of biological mechanisms that contribute to carbohydrate-induced hypertriacylglycerolemia. The clinical rationale behind mechanistic studies is this: if carbohydrate-induced hypertriacylglycerolemia shares a metabolic basis with endogenous hypertriacylglycerolemia (that observed in subjects consuming high-fat diets), then a similar atherogenic risk may be more likely than if the underlying metabolic mechanisms differ. The third focus of the paper is on both the positive metabolic changes that occur when high-carbohydrate diets are consumed and the potentially negative health effects of such diets. The review concludes with a summary of some important research questions that remain to be addressed. These issues include the level of dietary carbohydrate that induces carbohydrate-induced hypertriacylglycerolemia, whether the phenomenon is transient or can be avoided, whether de novo lipogenesis contributes to the phenomenon, and what magnitude of triacylglycerol elevation represents an increase in disease risk.

Reduced oxidative susceptibility of LDL from patients participating in an intensive atherosclerosis treatment program.

The goal of this investigation was to determine whether participation in an atherosclerosis treatment program would reduce the oxidative susceptibility of LDL from patients with coronary artery disease. The treatment program included intensive exercise therapy, stress management, and consumption of a diet containing 10% fat. The size and antioxidant and lipid contents of LDL particles from 25 patients were analyzed at baseline and after 3 mo of therapy. The susceptibility of LDL to copper-mediated oxidation was measured by a conjugated diene assay and headspace gas chromatography (HSGC). Atherosclerosis treatment significantly reduced plasma total cholesterol and apolipoprotein B concentrations and the molar ratio of LDL cholesterol ester to apolipoprotein B (P < 0.01). The LDL content of alpha-tocopherol and beta-carotene was increased (27% and 17%, respectively, P < 0.04) and the molar ratio of LDL cholesterol ester the sum of LDL alpha-tocopherol and LDL beta-carotene decreased from 159 at baseline to 122 at 3 mo (P < 0.01). The lag phase of LDL conjugated diene formation increased 24%, whereas the maximum rate of oxidation slowed 29% (P < 0.01). As assessed by HSGC, copper-catalyzed formation of volatile lipid oxidation products was reduced 15% (P < 0.007); the reduction in volatiles was correlated with an increase in the alpha-tocopherol content of LDL (r=-0.48, P < 0.01). The principal determinants of reduced LDL oxidative susceptibility were the particle contents of alpha-tocopherol and beta-carotene. To our knowledge, this is the first report to document a reduction in LDL oxidation in coronary artery disease patients undergoing atherosclerosis-reversal therapy.

GFAAS determination of ultratrace quantities of organotins in sea-water by using enhancement methods.

Tributyltin in sea-water is preconcentrated by extraction into toluene and determined by enhanced graphite-furnace atomic-absorption (GFAAS) at ultratrace concentrations (as low as 1.0 mug l .) equal to or lower than the toxic limits for aquatic organotins. Toluene is preferred to MIBK, chloroform or hexane as the solvent. Sea salts, in concentrations as low as 0.1%, critically interfere with GFAAS tin determinations, and must be removed by washing the extract with demineralized water. Signal enhancement effected by inserting L'vov platforms in the graphite furnace tubes or by adding ammonium dichromate to the analyte solution is nearly additive when both methods of enhancement are combined.

Effect of n-3 fatty acid-rich fish oil supplementation on the oxidation of low density lipoproteins.

This study was aimed at determining the effect of fish oil supplementation on copper-catalyzed oxidation of low density lipoproteins (LDL) from nine hypertriglyceridemic human subjects. A rapid headspace gas chromatographic method was used to measure the volatile oxidation products from LDL. Propanal and hexanal were the major volatile products formed in the oxidation of n-3 and n-6 polyunsaturated fatty acids (PUFA), respectively. Fish oil supplementation resulted in a significant increase in propanal formation from 3.7 to 13.4 nmol/mL LDL (P < 0.01); it also resulted in small decreases in pentanal formation from 14.7 to 11.4 nmol/mL LDL and in hexanal formation from 138 to 108 nmol/mL LDL (P < 0.05). The changes in peroxidation products paralleled the changes in LDL composition, which showed a significant increase in n-3 PUFA from 3.2 to 14.6% (P < 0.01) and a decrease in n-6 PUFA from 43.7 to 35.0% (P < 0.05). Propanal formation was highly and significantly correlated with n-3 PUFA content (r = 0.950, P < 0.001). Since total volatiles remained unchanged, this indicated that the two groups of LDL samples did not differ in overall oxidative susceptibility. Although fish oil intake did not alter the oxidative susceptibility of LDL, the chemically modified LDL particles generated a distinct pattern of volatile oxidation products that reflected changes in their fatty acid composition.

Getting the label in: practical research strategies for tracing dietary fat.

The observation that events occurring after consumption of a meal can directly affect metabolic risk has been gaining interest over the past 40 years. As a result, the desire for investigators to conduct postprandial studies has also increased. Study design decisions pertaining to the choice of meal quantity and composition are more difficult than may be readily apparent, and there is now ample evidence available in the literature to suggest that what is fed on the test day significantly affects postprandial metabolism and can therefore influence interpretation of results. In addition, events occurring before the testing day (food intake and activities) can also have an impact on the observed postprandial response. The goal of this review is to present aspects of study design critical to the investigation of postprandial metabolism. These details include subject preparation, meal quantity, form and composition, as well as sampling protocols for measuring metabolites. Key factors and practical examples are provided to minimize the impact of nonresearch variables on subject variability. Finally, aspects related to using stable isotope tracers to measure metabolism of meal fat are discussed, including choice of tracer form, dose and delivery in food. Given that fed-state events contribute significantly to chronic disease risk, improved methods to study the absorption and disposal of food energy will support the development of strategies designed to prevent and treat diseases associated with overconsumption of nutrients.

Recent findings in the study of postprandial lipemia.

The study of postprandial metabolism is in the early stages compared with other areas of atherosclerosis research. Recent advances in postprandial research have included improvements in methodology and the investigation of factors that modulate the lipemic response to a meal. Enough studies have now been performed that normal ranges have been identified for blood triacylglycerol (TAG) concentrations that occur after a healthy patient consumes a standardized-mixed meal or a high-fat shake designed to elicit lipemia. Typical postprandial concentrations of other metabolites, such as apolipoproteins B48 and B100 or gastrointestinal hormones (eg, cholecystokinin), have not been studied sufficiently to be able to qualify what represents a standard postprandial response. The method of data analysis is also a key point to consider. Data from children are now becoming available, and the specific effects of ethnicity have just begun to be explored. New areas of study include the effects of different fatty acids (monosaturates or polyunsaturates), the sources of chylomicron lipids (dietary TAG and cholesterol versus that newly synthesized in the body), and the effects of alcoholic beverages consumed with the meal. Variables that can also affect the results of a meal test are under investigation. These include the type of food that is consumed the day before the meal test, the time of day the test is performed, and the palatability of the food. Given solid evidence that delayed postprandial lipemia is an independent risk factor for coronary heart disease, future scientific investigation in the area of postprandial metabolism is likely to yield discoveries that will significantly contribute to advancements in disease treatment.

Dietary carbohydrate's effects on lipogenesis and the relationship of lipogenesis to blood insulin and glucose concentrations.

The process by which dietary carbohydrate is transformed into fat in the human body is termed de novo lipogenesis. New methods for the measurement of this process in humans are available and have been used to investigate the role of the carbohydrate form (fed as a liquid or solid), the level of processing of carbohydrate in foods, and the role of lipogenesis in the control of liver triacylglycerol secretion. The present paper will discuss how research results are affected by both the physical state of the carbohydrate in the diet and by the metabolic state of individual research subjects. Of interest is the relationship between the glycemic index of a food (or indicators of a food's glycemic index) and that food's ability to stimulate lipogenesis in humans. Given the increasing prevalence of obesity worldwide, future scientific emphasis will expand methods to quantitate the lipogenic potential of specific foods and dietary patterns and investigate how the metabolic state of insulin resistance affects lipogenesis and/or contributes to obesity.

Effect of dietary carbohydrate on triglyceride metabolism in humans.

When the content of dietary carbohydrate is elevated above the level typically consumed (>55% of energy), blood concentrations of triglycerides rise. This phenomenon, known as carbohydrate-induced hypertriglyceridemia, is paradoxical because the increase in dietary carbohydrate usually comes at the expense of dietary fat. Thus, when the content of the carbohydrate in the diet is increased, fat in the diet is reduced, but the content of fat (triglycerides) in the blood rises. The present article will review studies of carbohydrate-induced hypertriglyceridemia, highlighting data obtained in fasted subjects habituated to high carbohydrate diets, data obtained from subjects in the fed state, and metabolic studies investigating fatty acid and triglyceride synthesis in subjects consuming diets of different carbohydrate content. The available data have been recently expanded by new methodologies, such as the use of stable isotopes, to investigate the metabolism of sugars in humans in vivo. Given the significant increase in body weight observed in the American population over the past decade and the changing availability of carbohydrate in the food supply, future studies of carbohydrate-induced hypertriglyceridemia promise to provide important information of how the macronutrient composition of the diet can influence health.

The Effect of Calcium Carbonate on the Stability of Acid Treated Papers.

Exposure of kraft wood pulps to an acidic medium results in a destabilization of wood pulp. The degree of destabilization appears to depend on the concentration of acid the pulp is exposed to. The addition of calcium carbonate to acid destabilized pulp does not restore the pulp to its original stability. The absorption of alkali metals is pH dependent which could explain the destabilization of wood pulps when exposed to an acid medium. A number of questions arise about the merit of stabilizing degraded paper documents by deacidification with alkaline earth salts and the usefulness of an alkaline reserve in paper.

VLDL-triglyceride production after alcohol ingestion, studied using [2-13C1] glycerol.

We used [2-13C1]glycerol to characterize very low density lipoprotein (VLDL)-triglyceride kinetics and intrahepatic glycerol metabolism in normal men (n = 4) after alcohol (EtOH) ingestion. [2-13C1]glycerol was infused before and after the consumption of 48 g EtOH or a placebo. Three additional subjects also received [1-13C1]acetate in addition to the [2-13C1]glycerol with EtOH treatment. Incorporation of tracer into the glycerol or fatty acid moiety of VLDL-triglyceride was measured by gas chromatography-mass spectrometry and used to calculate VLDL-triglyceride production rates. Intrahepatic triose-phosphate enrichments were also calculated based on mass isotopomer distribution analysis of plasma glucose. There was no difference in VLDL-triglyceride production rates after 48 g EtOH (11.9 +/- 3.7 mg/kg/h) or placebo (14.7 +/- 3. 3 mg/kg/h). The VLDL-triglyceride rate constants calculated by kinetic modeling using the glycerol and acetate tracers in the combined isotope infusion subjects were very closely correlated (r 2 = 0.94). The peak VLDL-glycerol enrichments after EtOH were 22.5 +/- 3.3% versus 7.6 +/- 0.8% after placebo (P < 0.001), while intrahepatic triose-phosphate enrichments were 19.8 +/- 1.3% and 13. 1 +/- 1.2% (P < 0.001), respectively. Moreover, the calculated asymptotic VLDL-glycerol enrichments (representing the hepatic alpha-glycerol phosphate enrichment) were significantly higher after EtOH than placebo. The higher ratio of VLDL-glycerol to triose-phosphate labeling after EtOH suggests a metabolic block at glycerol 3-phosphate dehydrogenase. We conclude that consumption of 48 g EtOH does not increase VLDL-triglyceride production in normal men but does cause accumulation of tracer in hepatic alpha-glycerol phosphate.

Predictors of plasma triglyceride elevation in patients participating in a coronary atherosclerosis treatment program.

PURPOSE: Low-fat, high-carbohydrate diets have been used successfully to prevent and treat coronary heart disease, although these diets have been shown to cause elevations in fasting plasma triglyceride concentrations. The present study investigated metabolic factors (glucose, insulin, body weight) associated with changes in plasma triglyceride concentrations in patients participating in a comprehensive, multidisciplinary program, which included the use of a very low-fat diet designed to regress atherosclerotic cardiovascular disease. METHODS: Thirty-six patients were entered into the study and placed on a 10% fat diet. Body mass index and fasting plasma insulin, glucose, lipids, and apolipoproteins were assessed at entrance into and after 3 months of participation in the program. Statistical analysis (discriminant function analysis) was used to identify factors that predicted elevations in plasma triglyceride that occurred during therapy. RESULTS: For the entire group, significant reductions in body weight (-2.4%), fasting glucose (-6%), total cholesterol (-8%), and low-density lipoprotein cholesterol (-11%) were observed, while insulin and triglycerides showed no significant changes. Twenty-one of the patients experienced an increase in fasting triglyceride concentration of 10% or greater. CONCLUSIONS: Three variables (baseline body mass index and fasting triglyceride and insulin concentrations) accurately classified 90% of those who would experience a > or = 10% elevation in triglycerides (P = 0.0002) and 67% of those who experienced no change. The present analysis provides a practical algorithm for clinicians to predict which patients will experience significant elevations in plasma triglyceride concentration when undergoing risk factor reduction that includes the consumption of a very low-fat, high-carbohydrate diet.

(n-3) fatty acid supplementation in moderately hypertriglyceridemic adults changes postprandial lipid and apolipoprotein B responses to a standardized test meal.

The effects of (n-3) fatty acids on the postprandial state were investigated by monitoring the alimentary responses to identical test meals fed to adults [n = 11; fasting triacylglycerol (TG) 2.55 +/- 0.24 mmol/L; mean +/- SEM] after a self-selected diet baseline period (BLP) and then after a 6-wk (n-3) fatty acid period (FOP) [ approximately 5.2 g (n-3) fatty acids] and a 6-wk control oil period (COP) administered in random order. Samples were drawn immediately prior to the test meal (time 0) and then hourly from 2 to 6 h postmeal. Postprandial plasma triacylglycerol (TG) and TG-rich lipoprotein (TRL) TG apo B48, and B100 absolute concentrations were significantly lower after FOP than after COP or BLP, while plasma cholesterol was unchanged. Normalizing the results as increments over time 0 eliminated the diet effect on all but plasma TG. Time remained a significant effect for plasma TG, TRL TG, and TRL TC. Finally, only absolute TRL B48 and absolute and incremental plasma TG concentrations displayed significant time-diet interactions. These results suggest that postprandial TRL apo B reductions are likely caused by (n-3) fatty acid suppression of both hepatic and intestinal apoB secretion/synthesis. Altered TRL metabolism, i.e. changes in postprandial TG, cholesterol, apo B48, and increase in LDL particle size, may represent an additional mechanism for the reduced heart disease risk associated with fish [(n-3) fatty acid] consumption.

Characterization of organotin species using microbore and capillary liquid chromatographic techniques with an epifluorescence microscope as a novel imaging detector.

The novel application of a UV epifluorescence microscope as an imaging detector for microbore and capillary high-performance liquid chromatography (HPLC) is reported. The microscope is focused on an in-line quartz flow cell incorporated down stream of a microbore HPLC column or directly on an optically clear portion of fused-silica capillary columns for analyte detection. The effect of different fluorescent ligand to analyte ratios on detection limits is also reported, as well as the effect of different image volume sizes produced by changes in microscope objective lens magnification power. Determination of relative sensitivities an detection limits for methyl- and butyltin compounds, complexed with fluorescent dyes, reveals that the organotins show decreasing sensitivity as the number of alkyl substituents on the tin atom increases, with minimum detectable amounts of 6-160 pg of analyte-ligand complex.