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PubMed1989

Autocorrelation spectroscopy for particle sizing and stability tests of radiolabelled colloids.

In many nuclear medicine applications a well defined particle size and stability of administered colloids is of great importance. A fast and reliable sizing technique for routine quality control is therefore essential. This paper evaluates autocorrelation spectroscopy with an instrument capable of analysing several peaks simultaneously. A total of nine 99mTc-labelled colloids and one 99Y-labelled colloid were studied. The autocorrelation spectroscopy measurements were compared with the standard sizing technique of microfiltration. A good agreement between the sizing techniques was found for most of the colloids. The reproducibility of successive measurements was within +/- 12% and +/- 40% when using unimodal analysis and SDP analysis, respectively. Autocorrelation spectroscopy was found to be well suited for particle sizing and stability tests of radiolabelled colloids.

Colloids↗

PubMed2003

Contaminants and levels of occurrence in washed and shredded poly(ethylene terephthalate) from curbside collection. II: Validation of extraction procedures, particle size sampling and crystallinity.

Part I of this study showed that washed and dried, shredded poly(ethylene terephthalate) (PET) (flake) obtained from curbside collection when Soxhlet extracted contained 26 semivolatile contaminants below the US FDA threshold of 215 ppb and six above this level. This paper reports the validation of the Soxhlet extraction technique by comparison with total dissolution with trifluoroacetic acid (TFA). The work was carried out for two of the three particle size ranges obtained by grinding the PET flake (300-425 and 425-700 microm) and for the unground flake. Further validation was undertaken by comparison of contaminant levels determined by total dissolution with TFA and sonication with dichloromethane (DCM) using flake ground to the 0-300 microm size range. The levels of contaminants increased with decreasing particle size range, but X-ray diffraction measurements of degrees of crystallinity were similar for each PET particle size range, thus showing that the differences in contaminant levels were not due to variable percentages of the amorphous material from the tops and bottoms of shredded bottles, relative to the amounts of crystalline PET from the mid-sections of the bottles. Hence, it was postulated that the variations in contaminant levels were due to selective grinding of the more highly contaminated surfaces, whilst the larger particles incorporated the less contaminated interior material. The grinding was also strongly selective with respect to the amorphous flake. Analysis of the segregated amorphous and crystalline flake phases indicated that many contaminants were similarly absorbed into both phases, whilst some were preferred by the amorphous PET and others were preferred by the crystalline PET.

Conservation of Natural Resources↗

PubMed1996

Effects of gender and menopausal status on plasma lipoprotein subspecies and particle sizes.

The risk of coronary heart disease (CHD) is lower in women than in men, but increases in women after menopause. Some of the gender, age, and menopausal-related differences in CHD risk may relate to differences in lipoprotein subspecies. We therefore examined these subspecies in three groups of healthy subjects: premenopausal women (W, n = 72, mean age 41.2 +/- 6.5), postmenopausal women (PMW, n = 74, 55.8 +/- 7.4), and men (M, n = 139, 48.8 +/- 10.7). We measured plasma levels of lipids, lipoprotein cholesterol, apolipoproteins A-I, A-IV, B, C-III, and E, and lipoprotein subspecies Lp A-I, Lp A-I:A-II, Lp B, Lp B:C-III, and Lp B:E, as well as LDL and HDL particle sizes. Our data indicate that women have significantly higher values of HDL-C, apoA-I, apoE, and Lp A-I; larger LDL and HDL particle sizes; and lower values of triglyceride, apoB, and Lp B:C-III particles than men, with no difference in Lp A-I:A-II. Postmenopausal status was associated with significantly higher values of total cholesterol, triglyceride, VLDL-C, and LDL-C; increased levels of apoB, C-III, and E; elevated values of Lp B, Lp B:C-III, and Lp B:E; and lower levels of HDL-C along with smaller HDL particle size. Moreover, we noted a strong correlation between LDL and HDL particle size. Our data are consistent with the concepts that male gender confers decreases in HDL subspecies due to lower Lp A-I levels; while postmenopausal status results in higher levels of all apoB-containing lipoproteins (Lp B, Lp B:C-III, and Lp B:E). The lipoprotein alterations associated with male gender and postmenopausal status would be expected to increase CHD risk.

Adult↗

PubMed2004

Influence of the valve lubricant on the aerodynamic particle size of a metered dose inhaler.

Presented in this work are the results of a study designed to investigate the impact of valve lubricant (i.e., silicone oil) on the aerodynamic particle size distribution (PSD) of a steroid suspension metered dose inhaler (MDI) containing propellant HFA-227. The objective of this study was to explore whether the valve lubricant, which is often used in MDI products to prevent valve sticking, can enter an MDI product and potentially impact the aerosol spray dynamics. The results of this work have shown that samples containing valves with high silicone levels produced a larger aerodynamic particle size (by cascade impaction) than samples with low-silicone or silicone-free valves. It is postulated that the presence of silicone in the product may increase the propensity for drug aggregation, thereby leading to an increase in the aerodynamic particle size of the emitted aerosol. These findings stress the importance of evaluating the effects of valve lubricant on the aerodynamic PSD in the early formulation development stage of an MDI.

Adrenal Cortex Hormones↗

PubMed2003

Fluvastatin increases LDL particle size and reduces oxidative stress in patients with hyperlipidemia.

The effects of fluvastatin on levels of urinary 8-iso-prostaglandin F2alpha (iPF2alphaIII), a marker of oxidative stress, and low-density lipoprotein (LDL) particle size in serum were investigated in patients with hypercholesterolemia. After 6 months of fluvastatin therapy, levels of urinary iPF2alphaIII decreased from 1720.1 +/- 392.0 to 539.6 +/- 75.5 pg/mg (p < 0.01), and LDL particle size increased from 24.3 +/- 0.3 to 26.5 +/- 0.2 nm (p < 0.001). These changes from the treatment of fluvastatin were not correlated with those of the serum LDL cholesterol (LDL-C) levels. The results imply that fluvastatin, with its unique antioxidant property among statins, reduces oxidative stress and increases LDL particle size simultaneously in hyperlipidemic patients.

Aged↗

PubMed1997

Toxicity of waterproofing spray is influenced by the mist particle size.

In a previous study, we showed that waterproofing sprays that are toxic generate mists with smaller particles than do nontoxic products. In this study, we made 4 waterproofing sprays (A, B, C and D) with identical ingredients but with different mist particle sizes and compared the pathological changes produced in the lungs of mice. The mist particle diameters were 32.8 +/- 3.2, 62.0 +/- 3.8, 89.1 +/- 4.1 and 143.2 +/- 5.0 microns for sprays A, B, C and D, respectively. Pathological lung changes were evaluated by a 6-criteria grading system (thickening of the alveolar septum, cellular infiltrations in the alveolar septum, alteration of the bronchial mucous membrane, hyperemia of the alveolar wall, transudative hemorrhage, and alveolar collapse). Sprays A and B caused significantly greater scores as compared to the control group for all the criteria except mucosal changes, whereas the changes from sprays C and D were slight and the differences in scores were not significant. These results suggest that toxicity of waterproofing spray is influenced by the mist particle size generated and may help manufacture safer waterproofing spray products.

Aerosols↗

PubMed2004

Effect of the particle size on the micro and nanostructural features of a calcium phosphate cement: a kinetic analysis.

The aim of this work is to investigate the possibility of controlling the final micro and nanostructural features of a calcium phosphate cement by modifying the particle size of the starting powder, and to study the effect of this parameter on the kinetics of the setting reaction. The development of calcium phosphate materials with tailored structures at the micro and nanoscale levels could allow the modulation of some specific responses in biologic phenomena such as protein adsorption and cell adhesion, which strongly depend on the nano-sized roughness of the interface. It is shown that the higher specific surface, produced by the reduction of the particle size of the powder, strongly accelerates the hydrolysis of the alpha-TCP into calcium-deficient hydroxyapatite. The higher degree of supersaturation attained in the solution favours the nucleation of smaller crystals. Thus, by increasing the specific surface of the starting powder in a factor of 5, the size of the precipitated crystals is strongly reduced, and the specific surface of the set cement increases by a factor of 2. The reduction of the particle size produces a substantial decrease of the setting time and accelerates the hardening of the cement without significantly affecting the final strength attained. The mechanical strength achieved by the cement cannot be univocally related to the degree of reaction, without considering the microstructural features.

Adhesiveness↗

PubMed2001

Site-specific Transmission Electron Microscope Characterization of Micrometer-sized Particles Using the Focused Ion Beam Lift-out Technique.

Micrometer sized particles have been studied to show that a high-quality transmission electron microscope (TEM) specimen can be produced, without the use of embedding media, from a site-specific region of chosen particles using the focused ion beam (FIB) lift-out (LO) technique. The uniqueness of this technique is that site-specific TEM LO specimens may be obtained from particles and from regions which are smaller than the conventional approximately 10-20 &mgr;m x 5 &mgr;m x approximately 0.1 &mgr;m dimensions of the LO specimen. The innovative FIB LO procedures are described in detail and TEM images of electron transparent specimens obtained from specific micrometer-sized particles are presented.

Journal Article↗

PubMed1977

Drug migration during drying of tablet granulations I: effect of particle size of major diluent.

Migration of a water-soluble drug, propoxyphene hydrochloride, during drying of tablet granulations was studied. Wet granulations of the drug were prepared using lactose as the major diluent and corn starch as a disintegrant. Particle-size fractions of lactose ranging from 53 to 177 micron in diameter were employed in different granulations to examine the effect of particle size of the major diluent on drug migration. Determination of drug concentration at various depths in a dried granulation bed was accomplished by using a drying cell consisting of four layers. A numerical coefficient of migration was developed to compare the extent of drug migration in the various lactose granulations. Migration increased with decreasing particle size of the major diluent, lactose. Two factors that may contribute to increased migration with smaller particles are increased entry suction due to decreased intragranular capillary size and increased intergranular contact area.

Chemistry, Pharmaceutical↗

PubMedDate not supplied

Effects of intake level of a mixed diet on chewing activity and on particle size of ruminated boli, ruminal digesta fractions and faeces of steers.

This study evaluated the effects of intake of a mixed diet on chewing activity during eating and rumination and the relationship between the chewing activity and the particle size of the ruminated boli, ruminal digesta fractions and faeces in steers. Six ruminally cannulated steers received a mixed forage/concentrate diet (68:32, dry matter basis). The diet was offered twice daily at approximately 1, 1.5 and 2 times the estimated maintenance energy requirements (low, medium and high intake, respectively) in a repeated 3 x 3 Latin square design. The rumens were emptied manually and samples of the ruminated boli and of the ruminal upper strata were collected at four different times throughout the day. The dry matter weight distribution of the total amount of recovered particles was determined by a wet-sieving procedure. Numerically, the effect of intake on the mean particle sizes of the different materials was small. However, the mean particle size was reduced by almost nine tenths from their size at intake of the mixed diet (4.78 mm) to defecation (0.51 mm). The total number of minutes chewing and eating and ruminating increased as the intake level increased. When related to 1 kg of dry matter intake, only the eating and chewing times were significantly longer for the high as compared to the medium intake. Rumination patterns were examined using a cosinor model. Data indicated that the average amount of time spent ruminating also increased as the intake level increased. The overall pattern of rumination was not impaired by higher intake levels. The amount of large (> or = 4 mm) particles that escaped per minute of rumination time between 3 and 7.5 h postfeeding was similar for all the intake levels. It was concluded that an active breakdown process occurred in the rumen which could cope with the higher intake levels of the mixed diet over the range of 1 to 2 times the maintenance energy requirement level.

Animal Feed↗

PubMed1990

[Measurement of particle size using a cascade impactor].

From the stand point occupational hygiene investigations of alveolar retention and particle deposition are of special importance. Determinations of particle size distribution of inhaled dusts have been performed by means of a cascade impactor. The evaluation and graphical presentation were performed by a personal computer. Proposals for further increasing the statement capability were derived (measurement at the workplace of the employee, analysis of the composition of the different particle size fractions).

Dust↗

PubMed2005

Effects of food deprivation and particle size of ground wheat on digestibility of food components in broilers fed on a pelleted diet.

The first aim of the experiment was to study the effect of wheat (Triticum aestivum) particle size on the digestibility of starch in a pelleted diet given to broilers. The second aim was to study the consequences of food deprivation before the excreta collection period (from 21 to 24 d). Wheat from a strong hardness cultivar was incorporated at 546.1 g/kg in diets. The other main ingredients were soybean meal (353.5 g/kg) and rapeseed oil (55.0 g/kg). Diets were given as pellets. The experimental design was a 2 x 2 factorial design testing two particle sizes of wheat flour and two procedures of a balance experiment (with or without food deprivation). Birds given diet C (wheat coarse grinding before pelleting) had significantly greater gizzard weight than birds fed on diet F (wheat fine grinding before pelleting). Starch digestibility value was significantly increased when birds were fed on diet F. This effect was halved by food deprivation. No significant effect of grain particle size was observed for protein and lipid digestibility values. However, food deprivation decreased apparent protein digestibility, with an effect which was more pronounced for fine than for coarse grinding. AMEN of the diet was significantly improved by fine grinding of wheat and decreased by food deprivation. However, no significant differences in growth performance were induced by differences in wheat grinding. No significant effect of grinding was observed on the water excretion:feed intake ratio. No significant difference was observed for vent score between treatments. There was over-excretion of starch in the first hours of refeeding following food deprivation.

Animal Feed↗

PubMed1999

LDL particle size distribution is associated with carotid intima-media thickness in healthy 50-year-old men.

Results of cross-sectional and prospective studies have suggested that small, dense low-density lipoprotein (LDL) particles predispose to coronary heart disease. We investigated the relationships between plasma concentrations of LDL subfractions and intima-media thickness (IMT) of the common carotid artery (CCA), quantified by B-mode ultrasound, in 94 healthy, 50-year-old men, all of whom were homozygous for the apolipoprotein E3 allele. A novel 3% to 7.5% polyacrylamide gradient gel was developed to provide separation of LDL subfractions with high resolution, as was a procedure to quantify plasma concentrations of these LDL subspecies. The LDL particle size distribution pattern obtained by the gradient gel electrophoresis procedure was in good agreement with the one obtained by a well-established, single-spin density gradient ultracentrifugation technique. LDL-II (particle size, 23.5 to 25.0 nm) was the most abundant subfraction, and its plasma concentration correlated closely with the total LDL cholesterol concentration (r=0. 61, P<0.001) but not with CCA IMT (r=-0.13, NS). In contrast, the plasma concentration of the predominant small, dense LDL particle subfraction (LDL-III; particle size, 22.5 to 23.5 nm) correlated strongly with CCA IMT (r=0.42, P<0.001). In multivariate analysis, the plasma concentration of the LDL-III subfraction contributed significantly to the variation in CCA IMT (R(2)=0.19). When plasma triglycerides and LDL cholesterol were forced into the multivariate model, 10% of the variation in CCA IMT was still accounted for by the LDL-III subfraction. In summary, use of a novel and sensitive gradient gel electrophoresis method for evaluation of LDL heterogeneity provided the basis for demonstrating an independent relation between the plasma concentration of small LDL and IMT of the CCA in healthy, middle-aged men.

Apolipoproteins B↗

PubMed2003

Techniques to improve the shear strength of impacted bone graft: the effect of particle size and washing of the graft.

BACKGROUND: When fresh morselized graft is compacted, as in impaction bone-grafting for revision hip surgery, fat and marrow fluid is either exuded or trapped in the voids between particles. We hypothesized that the presence of incompressible fluid damps and resists compressive forces during impaction and prevents the graft particles from moving into a closer formation, thus reducing the graft strength. In addition, viscous fluid such as fat may act as an interparticle lubricant, thus reducing the interlocking of the particles. METHODS: We performed mechanical shear testing in the laboratory with use of fresh-frozen human femoral-head allografts that had been passed through different orthopaedic bone mills to produce graft of differing particle-size distributions (grading). RESULTS: After compaction of fresh graft, fat and marrow fluid continued to escape on application of normal loads. Washed graft, however, had little lubricating fluid and better contact between the particles, increasing the shear resistance. On mechanical testing, washed graft was significantly (p < 0.001) more resistant to shearing forces than fresh graft was. This feature was consistent for different bone mills that produced graft of different particle-size distributions and shear strengths. CONCLUSIONS: Removal of fat and marrow fluid from milled human allograft by washing the graft allows the production of stronger compacted graft that is more resistant to shear, which is the usual mode of failure. Further research into the optimum grading of particle sizes from bone mills is required.

Bone Transplantation↗

PubMed1992

Effect of fat from whole soybeans on performance of dairy cows fed rations differing in fiber level and particle size.

Two trials were conducted with lactating dairy cows to determine effects on intake, performance, and chewing activity of supplemental fat in early lactation diets that differed in fiber level and particle size. In trial 1, whole raw soybeans were added at 11.6% of ration DM to alfalfa silage-based TMR containing either finely chopped silage or the same silage with 8.1% coarsely chopped alfalfa hay. Each combination of soybeans (0 or 11.6%) and silage (fine or hay added) was fed as an isocaloric, isonitrogenous TMR to eight Holstein cows in early lactation in a replicated Latin square design with 4-wk periods. Addition of soybeans decreased DMI for fine silage. With silage plus hay, soybean addition decreased milk yield and protein content but increased fat test so that FCM was unchanged. Silage plus hay promoted chewing activity with no interaction of forage particle size with fat addition on chewing activity. In trial 2, TMR based on alfalfa and corn silage contained either 25 or 29% NDF and 0 or 11.6% soybeans. Otherwise, trials 1 and 2 were similar. Soybean addition decreased DMI with low NDF diets. Addition of fat from soybeans had no effect on milk yield or composition, but low fiber decreased fat test and chewing activity. When .4 to .5 kg/d of supplemental fat from whole raw soybeans was fed, higher dietary NDF and larger particle size promoted greater intake with no effect on FCM yield.

Animal Feed↗

PubMed1984

Effects of particle size and formaldehyde treatment of soybean meal on milk production and composition for dairy cows.

Twenty-four lactating dairy cattle were used to study the effects of formaldehyde treatment and reduction of particle size of soybean meal on milk production and composition. Cows were fed diets containing one of the following soybean meals: 1) untreated, coarse; 2) untreated, fine; 3) formaldehyde-treated, fine. Formaldehyde reduced the solubility of soybean meal protein from 22.7 to 2.9%. Grinding soybean meal reduced particle size from 842 to 249 micron. Formaldehyde treatment did not affect intake or milk production but resulted in higher efficiency of milk production (1.43 versus 1.46 kg fat-corrected milk/kg dry matter intake). Milk protein (3.08 versus 2.85%) and solids-not-fat (8.51 versus 8.35%) contents were reduced by formaldehyde. Cows fed fine soybean meal had higher dry matter intakes (22.0 versus 20.8 kg dry matter/day) and gained more body weight; however, milk production was not affected by particle size. Grinding soybean meal reduced production efficiency (1.47 versus 1.42 kg milk/kg dry matter intake) and milk fat (3.70 versus 3.33%). Lack of production response and reduced milk protein from formaldehyde treatment suggests possible overprotection of protein. Fine grinding of soybean meal appeared to favor body weight gain rather than milk production.

Animals↗

PubMed1998

Mobilization of iron from coal fly ash was dependent upon the particle size and the source of coal.

Particulate air pollution, including coal fly ash, contains iron, and some of the pathological effects after inhalation may be due to reactive oxygen species produced by iron-catalyzed reactions. The objective of this study was to determine whether iron, present in coal fly ash, was mobilized, leading to ferritin induction in human airway epithelial cells, and whether the size of the particles affected the amount of iron mobilized. Three types of coal were used to generate the three size fractions of fly ash collected. The Utah coal fly ash was generated from a bituminous b coal, the Illinois coal fly ash from a bituminous c coal, and the North Dakota coal fly ash from a lignite a coal. Three size fractions were studied to compare the amount of iron mobilized in human airway epithelial (A549) cells and by citrate in cell-free suspensions. The size fractions selected were fine (<2.5 microm) and coarse (2.5-10 microm) components of PM10, airborne particulate matter <10 microm in diameter, and the fraction greater than 10 microm. Coal fly ash samples were incubated with 1 mM citrate to determine if iron associated with coal fly ash could be mobilized. Iron was mobilized by citrate from all three size fractions of all three coal types to levels as high as 56.7 nmol of Fe/mg of coal fly ash after 24 h. With all three coal types, more iron was mobilized by citrate from the <2.5 microm fraction than from the >2.5 microm fractions. Further, the mobilized iron was in the Fe(III) form. To determine if iron associated with the coal fly ash could be mobilized by A549 cells, cells were treated with coal fly ash, and the amount of the iron storage protein ferritin was determined after 24 h. Ferritin levels were increased by as much as 11.9-fold in cells treated with coal fly ash. With two of the three types of coal studied, more ferritin was induced in cells treated with the <2.5 microm fraction than with the >2.5 microm fractions. Further, inhibition of the endocytosis of the coal fly ash by the cells resulted in ferritin levels that were near that of the untreated cells, suggesting that iron was mobilized intracellularly, not in the culture medium. The results of this study suggest that differences in particle size and speciation of iron may affect the release of iron in human airway epithelial cells.

Air Pollutants, Occupational↗

PubMedDate not supplied

Effects of particle size on blood clearance and tissue uptake of lipid emulsions with different triglyceride compositions.

BACKGROUND: Particle size of IV lipid emulsions affects the catabolism of long-chain triglyceride (LCT) emulsions, but little is known about its effect on the catabolism of medium-chain triglyceride (MCT)- and fish oil (FO)-containing emulsions. METHODS: Large (VLDL size), intermediate, and small (IDL size) emulsions with different triglyceride (TG) compositions were labeled with [3H]cholesteryl oleoyl ether: LCT (triolein 100%), MCT:LCT (trioctanoin:triolein 50%:50%), MCT:LCT:FO (trioctanoin:triolein:triDHA 50%:40%:10%), and FO (triDHA 100%). Emulsions (0.4 mg TG/mouse) were injected into C57BL/6J mice, and blood clearance and tissue uptake of emulsion particles were determined. RESULTS: Large emulsion particles had 2- to 3-fold faster fractional catabolic rates (FCR) compared with small particles with the same TG content. There was 1.5- to 2.0-fold higher FCR of large FO-containing emulsions (FO and MCT:LCT:FO) compared with large LCT and MCT:LCT emulsions, whereas effects of FO on FCR in small emulsions were not observed. Large FO-containing emulsions were taken up more by adipose tissue compared with small particles with concomitant decreases in hepatic uptake. Preinjection of heparin reduced heart and adipose uptakes of FO and MCT:LCT:FO emulsions with increased uptake by liver, suggesting a role of lipoprotein lipase in catabolism of FO-containing emulsions. CONCLUSIONS: In a mouse model, FO addition to large emulsions increased blood clearance and changed organ delivery. In contrast, there was no or little effect when particle size became smaller. We hypothesize that in humans, FO addition to lipid emulsions can help target emulsion delivery to certain extrahepatic tissues, a factor that may be of use for delivering specific fatty acids, or even drugs, to specific organs.

Analysis of Variance↗