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PubMed2000

Comparison of nebulized particle size distribution with Malvern laser diffraction analyzer versus Andersen cascade impactor and low-flow Marple personal cascade impactor.

Particle size of nebulized aerosols can be measured directly using laser diffraction or by evaluating aerodynamic properties by cascade impaction. As of today, there are no generally accepted standards for measuring particle size distribution from nebulizers. Laser diffraction has been questioned because of potential evaporative losses of the small particles at the edge of the plume, causing an apparent shift in the particle size distribution and thus a larger mass median diameter (MMD). When particle-sizing wet aerosols, cascade impaction may give rise to an apparent shift in the distribution, resulting in a smaller mass median aerodynamic diameter (MMAD) due to evaporative losses of aerosol droplets as they enter the impactor at ambient temperature. The modified low-flow Marple 296 Personal Cascade Impactor (MPCI) is currently being proposed as the European standard for wet aerosol analysis to minimize evaporative losses during sampling. The present study compared the particle size distribution of salbutamol and sodium cromoglycate aerosols nebulized by the Pari LC Star, using laser diffraction (Malvern Mastersizer X; MMX) and cascade impaction (Andersen Cascade Impactor [ACI] and the commercially available MPCI), which was either at ambient temperature or cooled to the nebulized aerosol temperature (10 degrees C). MMDs obtained with the MMX were virtually identical to the MMADs measured with both impactors when cooled with no significant differences in geometric standard deviation (sigma(g)). When the impactors were operated at ambient temperature, MMADs were smaller (18 to 30%) with a significantly larger sigma(g) (p < 0.05) compared to the MMX. These findings suggest that droplet distribution data for wet aerosol where evaporation process has not been minimized must be viewed with caution. There was no evidence suggesting a significant evaporative loss of small droplets from the edge of the plume during laser particle sizing. The MPCI does not minimize evaporative losses of aerosol particles during sampling.

Aerosols↗

PubMed1994

Optimum particle size of corn and hard and soft sorghum for nursery pigs.

A total of 240 weanling pigs (22 d of age and 5.3 kg average BW) were used to determine the effects of particle size of corn and two sorghum hybrids on diet processing, growth performance, apparent digestibility of nutrients, and morphology of the stomach and intestines in weanling pigs. Treatments were corn, hard endosperm sorghum, and soft endosperm sorghum milled to particle sizes (geometric mean) of 900, 700, 500, and 300 microns, in a 3 x 4 factorial arrangement. All diets were pelleted and the pigs were allowed to consume feed and water on an ad libitum basis. As particle size was reduced, production rate (tons/hour) decreased and energy required to mill (kilowatt hours/ton) increased. Corn required more energy to mill and had a lower production rate than the sorghums. For d 0 to 14, ADG and gain/feed increased linearly (P < .009 and P < .002, respectively) as particle size was decreased to 300 microns. However, there was a grain source x particle size interaction; pigs fed corn responded to particle size reduction more than pigs fed the sorghums (P < .04). For d 0 to 35, pigs fed diets with corn grew 23% faster and were 6% more efficient (P < .001) than pigs fed diets with sorghum. Gain/feed responded quadratically to reduction of particle size (P < .01), with maximum gain/feed at 500 microns for all grains. Lowest cost of gain (including milling and ingredient costs) was achieved at 500 to 700 microns for corn and 500 microns for the hard and soft sorghums. These data suggest that response to reducing particle size is greatest during the first 2 wk postweaning and that optimal particle size for corn and sorghums increases with age of nursery pigs.

Amino Acids↗

PubMed2003

Studies on the interaction of water with ethylcellulose: effect of polymer particle size.

The purpose of this research was to investigate the interaction of water with ethylcellulose samples and assess the effect of particle size on the interaction. The distribution of water within coarse particle ethylcellulose (CPEC; average particle size 310 micro m) and fine particle ethylcellulose (FPEC; average particle size 9.7 micro m) of 7 cps viscosity grade was assessed by differential scanning calorimetry (DSC) and dynamic vapor sorption analysis. The amounts of nonfreezing and freezing water in hydrated samples were determined from melting endotherms obtained by DSC. An increase in water content resulted in an increase in the enthalpy of fusion of water for the two particle size fractions of EC. The amount of nonfreezable water was not affected by the change in particle size at low water contents. Exposure of ethylcellulose to water for 30 minutes is sufficient to achieve equilibration within the hydrated polymer at 47% wt/wt water content. The moisture sorption profiles were analyzed according to the Guggenheim-Anderson-de Boer (GAB) and Young and Nelson equations, which can help to distinguish moisture distribution in different physical forms. The amount of externally adsorbed moisture was greater in the case of FPEC. Internally absorbed moisture was evident only with the CPEC. In light of these results, an explanation is offered for the success of FPEC in wet-granulation methods where CPEC was not successful.

Calorimetry, Differential Scanning↗

PubMed1992

Changes in particle size of high density lipoproteins during incubation with very low density lipoproteins, cholesteryl ester transfer protein and lipoprotein lipase.

Previous reports have produced conflicting views of the effects of lipoprotein lipase (LPL) on the particle size distribution of high density lipoproteins (HDL). In this study we have investigated the changes in particle size of HDL promoted by the interaction of LPL, the cholesteryl ester transfer protein (CETP) and very low density lipoproteins (VLDL). When the plasma fraction of d less than 1.21 g/ml (containing all lipoprotein fractions) was incubated for 24 h with bovine milk LPL alone or with CETP alone, there was relatively little change in the particle size distribution of HDL. When both LPL and CETP were added to the lipoprotein mixture, there was a substantial reduction in the particle size of HDL. This reduction in HDL particle size was found to be a direct function of the concentration of CETP. It was also influenced by the concentrations of VLDL and LPL, although in these cases the relationships were complex. When mixtures of the plasma fraction of d = 1.006-1.21 g/ml (this fraction includes low density lipoproteins and HDL but not VLDL) were supplemented with both LPL and CETP and incubated in the presence of varying concentrations of added VLDL, there was a progressive increase in the conversion of HDL into very small HDL particles of radius 3.7 nm as the concentration of VLDL triacylglycerol increased up to about 400 nmol/nml. However, further increases in the concentration of VLDL were accompanied by a progressive reduction in the formation of small HDL particles until, at higher VLDL concentrations, the effect was all but abolished. There was a similar enhancement in the formation of small HDL when LPL was added at low but not at high concentrations. These findings are consistent with the existence of two opposing processes. On the one hand there is likely to be a synergism between CETP and the non-esterified fatty acids (NEFA) released by LPL; this will favour a reduction in HDL particle size. On the other hand, the transfer of lipolysis products from VLDL to HDL may mask any such particle size reduction. The fact that the reduction in HDL particle size promoted by LPL, CETP and VLDL was found to be all but abolished by adding fatty acid-poor albumin to the incubation mixture is consistent with the proposition that NEFA are involved in the process. It also suggests, however, that the phenomenon may have little if any physiological significance.

Adult↗

PubMed1998

Modulation of LDL particle size after an oral glucose load is associated with insulin levels.

Individuals with a predominance of small low-density lipoprotein (LDL) particles appear to be at increased risk for coronary artery disease. The purpose of this study was to determine whether the LDL particle size was modulated in response to a 75-g oral glucose load. Overall, there were no significant changes in the LDL particle size after glucose load. However, the difference in LDL particle size (deltaLDL size) between the fasting and 2-h post-load states was inversely correlated with the fasting LDL particle size. Also, deltaLDL size was positively correlated with BMI and the post-load glucose levels. Forward stepwise regression analysis revealed three parameters as independent factors capable of modulating LDL particle size: BMI, fasting insulin, and post-load glucose levels. After adjustment for BMI and glucose levels, the levels of fasting and 2-h post-load insulin remain independent determinants of deltaLDL size. These results suggest that plasma insulin levels during glucose load modulate LDL particle size.

Adult↗

PubMed1999

Processing, mixing, and particle size reduction of forages for dairy cattle.

Adequate forage amounts in both physical and chemical forms are necessary for proper ruminal function in dairy cows. Under conditions in which total amounts of forage or particle size of the forage are reduced, cows spend less time ruminating and have a decreased amount of buoyant digesta in the rumen. These factors reduce saliva production and allow ruminal pH to fall, depressing activity of cellulolytic bacteria and causing a prolonged period of low ruminal pH. Insufficient particle size of the diet decreases the ruminal acetate-to-propionate ratio and reduces ruminal pH. The mean particle size of the diet, the variation in particle size, and the amount of chemical fiber (i.e., NDF or ADF) are all nutritionally important for dairy cows. Defining amounts and physical characteristics of fiber is important in balancing dairy cattle diets. Because particle size plays such an important role in digestion and animal performance, it must be an important consideration from harvest through feeding. Forages should not be reduced in particle size beyond what is necessary to achieve minimal storage losses and what can be accommodated by existing equipment. Forage and total mixed ration (TMR) particle sizes are potentially reduced in size by all phases of harvesting, storing, taking out of storage, mixing, and delivery of feed to the dairy cow. Mixing feed causes a reduction in size of all feed particles and is directly related to TMR mixing time; field studies show that the longest particles (>27 mm) may be reduced in size by 50%. Forage and TMR particle size as fed to the cows should be periodically monitored to maintain adequate nutrition for the dairy cow.

Animal Feed↗

PubMed2003

Impact of postprandial variation in triglyceridemia on low-density lipoprotein particle size.

The fasting atherogenic dyslipidemia of visceral obesity, which includes the presence of small, dense low-density lipoprotein (LDL) particles, is predictive of an increased risk of coronary heart disease (CHD). It has also been suggested that progression of atherosclerosis may be accelerated in the presence of postprandial hyperlipidemia independently from the fasting dyslipidemic state. Studies have shown that the best predictor of postprandial hyperlipidemia and of the small, dense LDL phenotype is fasting triglyceride (TG) concentration. In the present study, we evaluated the impact of postprandial hypertriglyceridemia on the variation in LDL particle size. Fasting (0 hour) and postprandial changes (2, 4, 6, and 8 hours) in LDL particle size were measured by nondenaturing 2% to 16% polyacrylamide gel electrophoresis in a sample of 49 men (mean age +/- SD: 46.6 +/- 9.2 years) who underwent a standardized breakfast with a high-fat (64% calories as fat) content. The postprandial increase in TG levels was associated with a transient reduction in LDL particle size, the most substantial reduction being observed 4 hours (-1.0 +/- 2.4 A) after the oral fat load. Although there were strong correlations between TG-rich lipoprotein (TRL)-TG levels and LDL particle size in the fasting state (r=-0.71, P<.0001) as well as 4 hours after the oral fat load (r=-0.70, P<.0001), changes in TRL-TG concentrations during the postprandial state (from time 0 to 4 hours) were not associated with changes in LDL particle size during this period (r=-0.04, not significant [NS]). However, among subgroups of men matched for similar fasting TRL-TG levels (n=12), subjects with the highest total area under the curve (AUC) of TRL-TG after the fat load were characterized by smaller LDL particle size at 6 and 8 hours compared with men with the lowest AUC TRL-TG (P<.02). Men displaying the highest postprandial AUC TRL-TG were also characterized by the greatest accumulation of visceral adipose tissue (AT) (P<.05). These results indicate that the hypertriglyceridemic (hyperTG) state induced by a high-fat meal is associated with a transient reduction in LDL peak particle diameter, which is not proportionate, however, to the level of TG achieved in the postprandial state. Furthermore, despite similar TG levels at baseline, viscerally obese men with an impaired postprandial lipemia had smaller LDL particles at the end of the oral fat load than obese men with a lower accumulation of visceral AT.

Adult↗

PubMed2000

Effect of particle size and sodium ion concentration on anaerobic thermophilic food waste digestion.

Serial basic tests were conducted for the determination of fundamental kinetics and for the actual application of kinetic parameters to food waste digestion with precise measurement of methane production. The effects of food particle size and sodium ion concentration on the anaerobic thermophilic food waste digestion process were investigated. Results of serial tests for the determination of fundamental kinetic coefficients showed the value of k (maximum substrate utilization rate coefficient) and KS (half-saturation coefficient) as 0.24 hr-1 and 700 mg/L, respectively, for non-inhibiting organic loading range. The substrate inhibition coefficient (Ki) was 1000 mg/L for inhibiting organic loading range. No inhibition effect was shown until 5 g/L of sodium ion concentration was applied to the serum bottle reactor. However, the volume of methane gas was decreased gradually to the concentrations of more than 5 g/L of sodium ion applied. All sizes of food waste particle had the same constants (A: 0.45) but the maximum substrate utilization rate constant (kHA) was inversely proportional to particle size. As average particle size increased from 1.02 mm to 2.14 mm, kHA decreased from 0.0033 hr-1 to 0.0015 hr-1. Result reveals that particle size is one of the most important factors in anaerobic food waste digestion.

Bacteria, Anaerobic↗

PubMed2004

Particle interaction of lubricated or unlubricated binary mixtures according to their particle size and densification mechanism.

The aim of this study is to assess an experimental approach for technological development of a direct compression formulation. A simple formula was considered composed by an active ingredient, a diluent and a lubricant. The active ingredient and diluent were selected as an example according to their typical densification mechanism: the nitrofurantoine, a fragmenting material, and the cellulose microcrystalline (Vivapur), which is a typical visco-elastic material, equally displaying good bind and disintegrant properties. For each ingredient, samples of different particle size distribution were selected. Initially, tabletability of pure materials was studied by a rotary press without magnesium stearate. Vivapur tabletability decreases with increase in particle size. The addition of magnesium stearate as lubricant decreases tabletability of Vivapur of greater particle size, while it kept unmodified that of Vivapur of lower particle size. Differences in tabletability can be related to differences in particle-particle interactions; for Vivapur of higher particle size (Vivapur 200, 102 and 101), the lower surface area develops lower surface available for bonds, while for Vivapur of lower particle size (99 and 105) the greater surface area allows high particle proximity favouring particle cohesivity. Nitrofurantoine shows great differences in compression behaviour according to its particle size distribution. Large crystals show poorer tabletability than fine crystals, further decreased by lubricant addition. The large crystals poor tabletability is due to their poor compactibility, in spite of high compressibility and plastic intrinsic deformability; in fact, in spite of the high densification tendency, the nature of the involved bonds is very weak. Nitrofurantoine samples were then mixed with Vivapurs in different proportions. Compression behaviour of binary mixes (tabletability and compressibility) was then evaluated according to diluents proportion in the mixes. The mix of either nitrofurantoine large crystals or fine crystals with cellulose microcrystalline showed a negative interaction in all proportions, whatever particle sizes. The lubricant addition induced a positive interaction with Vivapur of greater particle size distribution (200, 102 and 101) favouring higher particle adhesivity, while it maintained unaltered that of Vivapurs of lower particle size (105 and 99). Definitely, when cohesive forces are predominant (Vivapur 105 and 99), the establishment of adhesive bonds between nitrofurantoine and Vivapur remain unnoticed; on the contrary, when cohesion bonds between microcrystalline cellulose particles are weakened by the presence of magnesium stearate, the existence of adhesion bonds between particles of different nature is in evidence, leading to a positive interaction.

Compressive Strength↗

PubMed2000

Propagation of viral-size particles in lymph and blood after subcutaneous inoculation.

OBJECTIVE: We investigated the propagation of viral-size particles by lymph and blood after subcutaneous injection. METHODS: In the canine model, transport of [99mTc] sulfur colloid particles of different sizes was studied in different settings in venous blood and lymph for 45 minutes after inoculation. RESULTS: The mean arrival time of particles in the blood was 2.10+/-0.46 minutes and 8.87+/-1.72 minutes in the lymph. Lymph flow in the canine leg was 28.79 +/-2.09) microl/min and was increased by leg massage. The particle concentration was 1000 times higher in the lymph fluid than in blood. Particle flux values were comparable in blood and lymph. The accumulation of particles in blood initially rose faster than in lymph. Accumulation in lymph rises slower but continues longer and reaches higher values. Ninety percent of the inoculum remains at the injection site for at least 45 minutes. Particle size matters more in blood distribution. Leg massage enhances particle transport by lymph. CONCLUSIONS: After subcutaneous injection, viral-size particles initially arrive in the blood and later in the lymph. Accumulation in lymph and blood increases for a prolonged time after inoculation. Results suggest possibilities for limiting the spread of infectious matter by early local antiviral treatment.

Animals↗

PubMed2002

Effects of forage particle size and grain fermentability in midlactation cows. II. Ruminal pH and chewing activity.

Our study investigated the effects of, and interactions between, level of dietary ruminally fermentable carbohydrate (RFC) and forage particle size on rumen pH and chewing activity for dairy cows fed one level of dietary NDF. Also, correlations between intake, production, chewing, and ruminal pH parameters were investigated. Eight cows (61 days in milk) were assigned to four treatments in a double 4 x 4 Latin square. Treatments were arranged in a 2 x 2 factorial design; finely chopped alfalfa silage (FS) and coarse alfalfa silage (CS) were combined with concentrates based on either dry, cracked-shelled corn (DC; low RFC) or ground, high-moisture corn (HMC; high RFC). Diets were fed ad libitum as a total mixed rations with a concentrate:forage ratio of 60:40. Diets averaged 18.7% crude protein, 24.0% neutral detergent fiber, 18.3% , acid detergent fiber and 27.4% starch on a DM basis. Mean particle size of the four diets were 6.3, 2.8, 6.0, and 3.0 mm for DCCS, DCFS, HMCCS, and HMCFS, respectively. Decreasing forage particle size decreased ruminal pH from 6.02 to 5.81, and increasing level of RFC decreased pH from 5.99 to 5.85. Minimum daily ruminal pH decreased from 5.66 to 5.47 when level of RFC was increased, and decreased from 5.65 to 5.48 when forage particle size decreased. Time below pH 5.8 per day increased from 7.4 h to 10.8 h when level of RFC increased, and increased from 6.4 h to 11.8 h when forage particle size was decreased. Area below 5.8 showed the same relationship with RFC and forage particle size. Also, forage particle size affected the postprandial pH pattern. Cows spent more time eating when fed CS compared with FS (274 vs. 237 min/d), and time spent eating decreased when level of RFC was increased (271 vs. 241 min/d). Decreasing forage particle size decreased time spent ruminating (485 vs. 320 min/d), rumination periods (15.3 vs. 11.7), and duration of rumination periods (29 vs. 26 min). Increasing level of RFC increased time spent ruminating per kg NDF intake (68.5 vs. 79.5 min/kg). Milk fat percentage was correlated to mean ruminal pH (r = 0.41), time spent below pH 5.8 (r = -0.55), and area below 5.8 (r = -0.57), but not to intake or chewing variables. DMI of particles retained on a screen equivalent in size to the top screen of the Penn State particle separator was the intake parameter explaining most of the variation in mean ruminal pH (r = 0.27) and was correlated to time spent ruminating (r = 0.61) and chewing (r = 0.61).

Animal Feed↗

PubMed2005

A novel quantitative trait locus on chromosome 1 with pleiotropic effects on HDL-cholesterol and LDL particle size in hypertensive sibships.

BACKGROUND: High-density lipoprotein (HDL)-cholesterol, triglycerides, and LDL particle size are correlated lipid traits. Abnormal levels of these traits are frequent in hypertensive individuals and contribute to increased risk of coronary heart disease (CHD). We performed univariate and bivariate linkage analyses to identify genomic regions that influence levels of these traits and exert pleiotropic effects on the traits in hypertensive sibships. METHODS: Subjects included 691 non-Hispanic white individuals (mean age 63.1+/-8.5 years, 57% women, 78% hypertensive) ascertained through sibships with two or more individuals diagnosed with hypertension before age 60 years. The LDL particle size was measured by polyacrylamide gel electrophoresis and triglycerides were log-transformed to reduce skewness. Genotypes were measured at 366 microsatellite marker loci distributed across the 22 autosomes. Univariate and bivariate linkage analyses were performed using a variance components approach. RESULTS: Significant (P < .001) genetic correlations were confirmed for all pairwise combinations of the traits. Univariate linkage analyses demonstrated evidence of linkage (defined as multipoint LOD scores > or =1.3) for HDL-cholesterol on chromosomes 1p, 3p, 9q, and 18q; for log triglycerides on chromosome 10q; and for LDL particle size on chromosomes 2p and 8p. Pairwise bivariate linkage analyses of the three traits revealed a region with pleiotropic effects on HDL-cholesterol and LDL particle size on chromosome 1p (LOD score 4.48). CONCLUSIONS: These findings indicate the presence of a quantitative trait locus on chromosome 1 that has pleiotropic effects on HDL-cholesterol and LDL particle size and may therefore influence CHD susceptibility in hypertensive sibships.

Aged↗

PubMed2000

Low density lipoprotein particle size and risk factors of insulin resistance syndrome.

The present study aimed to examine the association between low density lipoprotein (LDL) particle size and glucose and insulin variables and with other risk factors that have been related to insulin resistance syndrome. LDL particle size was determined in two groups of subjects who participated in the first examination of the Jerusalem Diabetes Study and who were invited to be re-examined after 8-10 years. The first group were non-diabetic subjects who were found to have at the first examination high insulin levels (above the sex and age specific 90th percentile of the 2 h post-glucose load insulin distribution). The second group was a random sample of individuals who had normal insulin and glucose levels at baseline. Sex-, Age- and body mass index (BMI) mean adjusted LDL-cholesterol (C), triglyceride (TG) and high density lipoprotein cholesterol (HDL-C) levels were significantly different among the LDL subclass groups. Fasting glucose levels and hemoglobin A(1c) did not differ statistically by LDL subclasses. Fasting and 2-h post load insulin levels were significantly higher in persons with LDL subclasses III and IV (small LDL), intermediate in those with LDL subclass II, and lowest in those with LDL subclass I (large LDL). Insulin resistance had an effect on the association between lipids, lipoproteins and LDL particle size. Multivariate analyses indicated that LDL-C, HDL-C and TG were independently associated with LDL particle size variability. The addition of 'insulin resistance' or insulin and glucose levels had no independent effects on LDL particle size. In conclusion, an association of LDL particle size with the cluster of risk factors that characterize the insulin resistance syndrome has been demonstrated. The association of 'insulin resistance' and LDL particle diameter, however, is not mediated directly through the level of insulinemia but via alterations in lipid metabolism.

Adult↗

PubMed1983

The effect of particle size and different extractants on the contents of heavy metals in roadside dusts.

The roadside dusts collected from three selected sites with marked differences in annual average daily traffic (AADT) values were divided into size classes according to particle size. The total, extractable, and water-soluble metal contents were determined using mixed acid, 1 M NH4OAc (pH 7.0), and distilled water as extractants. It was found that dust particles with a size smaller than 125 microns belonged to a homogeneous group and did not have a significant difference in metal contents. In using dust as a parameter to indicate the level of Pb contamination, a particle size of 125 microns and the extractable metal contents, using NH4OAc, should be used.

Dust↗

PubMed2004

Particle size of tin and phytate colloid in sentinel node identification.

BACKGROUND: Sentinel node navigation surgery (SNNS) has recently been introduced for various types of carcinoma. Numerous radioisotopes are used as tracers for SNNS. However, few reports have examined particle sizes of isotope colloids used in SNNS. MATERIALS AND METHODS: Tin and phytate colloids were used in the present study. Isotonic sodium chloride and tin solutions were mixed ratios of 1:4, 1:2, 1:1, 2:1, and 4:1. Calcium solution and Tc-phytate were mixed at ratios of 1:4, 1:2, 1:1, 2:1 and 4:1. Particle size was measured using a Coulter Model N4SD Sub-micron Particle Analyzer. RESULTS: When isotonic sodium chloride and tin solutions were mixed at ratios of 1:4, 1:2, 1:1, 2:1, and 4:1, particle size was 47 +/- 9, 96 +/- 10, 712 +/- 83, 925 +/- 66 and 1079 +/- 132 nm, respectively. As the ratio of tin solution decreased, colloid particle size increased. Particle size of phytate colloid varied from 174 +/- 39 nm to 1222 +/- 283 nm, according to calcium concentration. Phytate colloid particle size became larger as the ratio of phytate solution decreased. CONCLUSIONS: We ascertained that the particle size of tin and phytate colloids is controllable by manipulating the conditions under which the colloids form. These results will offer useful information when SNNS is performed.

Calcium↗

PubMed2003

Effect of obesity on HDL and LDL particle sizes in carriers of the null P207L or defective D9N mutation in the lipoprotein lipase gene: the Québec LipD Study.

BACKGROUND: We have recently demonstrated that French Canadians bearing a mutation in the lipoprotein lipase (LPL) gene present an impaired lipoprotein-lipid profile characterized by small low-density lipoprotein (LDL) and high-density lipoprotein (HDL) particles compared with healthy subjects. It has also been documented that obesity has a significant impact on HDL and LDL particle sizes. OBJECTIVE: To examine the extent to which obesity modulates HDL and LDL particle sizes among carriers of mutations in the LPL gene. SUBJECTS: Analyses were carried out in 206 heterozygous carriers of the D9N mutation (N=118) or the P207L mutation (N=88). MEASUREMENTS: Lipoprotein particle sizes were measured on whole plasma by nondenaturing polyacrylamide gradient gel electrophoresis. RESULTS: In general, body mass index (BMI) and waist circumference were significant correlates of LDL and HDL particle sizes among heterozygous carriers of the P207L or D9N mutation in the LPL gene, with relatively similar associations among men and women. Multivariate analyses indicated that variations in waist circumference but not BMI were an independent predictor of variations in both HDL particle size (5.2%, P=0.0005) and LDL particle size (5.9%, P=0.01) in the entire group of heterozygotes for LPL mutation in a model that included the nature of the LPL mutation (D9N vs P207L), gender, age, cholesterol and plasma TG levels. Interestingly, there was a significant interaction between plasma TG levels and waist circumference or BMI in modulating HDL particle size. Indeed, an increased waist circumference or BMI was associated with a significant reduction in HDL particle size among subjects with plasma TG levels 3.5 mmol/l). CONCLUSION: These results suggest that abdominal obesity, more so that overall obesity, is an important determinant of variations in LDL and HDL particle size among heterozygous carriers of mutations in the LPL gene, perhaps further contributing to modulate the risk of CHD in these individuals.

Body Mass Index↗

PubMed1990

The interaction of cholesteryl ester transfer protein and unesterified fatty acids promotes a reduction in the particle size of high-density lipoproteins.

Purified human cholesteryl ester transfer protein (CETP) has been found, under certain conditions, to promote changes to the particle size distribution of high-density lipoproteins (HDL) which are comparable to those attributed to a putative HDL conversion factor. When preparations of either the conversion factor or CETP are incubated with HDL3 in the presence of very-low-density lipoproteins (VLDL) or low-density lipoproteins (LDL), the HDL3 are converted to very small particles. The possibility that the conversion factor may be identical to CETP was supported by two observations: (1) CETP was found to be the main protein constituent of preparations of the conversion factor and (2) an antibody to CETP not only abolished the cholesteryl ester transfer activity of the conversion factor preparations but also inhibited changes to HDL particle size. In additional studies, the changes to HDL particle size promoted by purified CETP were inhibited by the presence of fatty-acid-free bovine serum albumin; by contrast, albumin had no effect on the cholesteryl ester transfer activity of the CETP. The possibility that albumin may inhibit changes to HDL particle size by removing unesterified fatty acids from either the lipoproteins or CETP was tested by adding exogenous unesterified fatty acids to the incubations. In incubations of HDL with either VLDL or LDL, sodium oleate had no effect on HDL particle size. However, when CETP was also present in the incubation mixtures the capacity of CETP to reduce the particle size of HDL was greatly enhanced by the addition of sodium oleate. It is concluded that the changes in HDL particle size which were previously attributed to an HDL conversion factor can be explained in terms of the interacting effects of CETP and unesterified fatty acids.

Adult↗

PubMed2004

[Determination of particle size distribution of nano-particles by capillary zone electrophoresis].

A new method was established for the determination of the size distribution of nano-particles by capillary zone electrophoresis (CZE). The data processing method for acquiring size distribution from primary electropherogram was investigated. The relative standard deviation of migration time was deduced by using dimethyl sulfoxide (DMSO) as an internal standard. Scattering effect of nano-particles was studied and a correction equation was established to correct this influence. The experimental results showed that the correction method was effective. After correction, the measuring results for the mixed samples with different mass ratios of PS50 and PS125 were almost the same with their theoretical values and the relative deviation was reduced from 35% to 5%. This method for the determination of size distribution is satisfactory.

Dimethyl Sulfoxide↗