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Tablets manufactured from micronized anhydrous nitrofurantoin exhibited unsatisfactory dissolution properties, whereas excellent results were obtained with unmilled drug material having fine particle size.
OBJECTIVES: To disclose if oral estradiol (E(2)), alone or in combination with natural progesterone (P) or medroxyprogesterone acetate (MPA), may modify the oxidizability of low density lipoprotein (LDL), and if the effect is achieved at physiological dosages. LDL oxidizability was assessed by the resistance to oxidation by copper and by the particle size profile, since small particles have increased oxidation susceptibility. METHODS: Thirty-three women received two consecutive, two-month length doses of 1 and 2 mg/day of oral E(2). They were then randomly assigned to a fourteen-day treatment of 2 mg/day E(2) plus either 300 mg/day P or 5 mg/day MPA. A parallel group of experiments was performed on a pool of baseline plasma, where hormones were added at the desired concentration. Lipoprotein levels, resistance of LDL to oxidation, and LDL particle diameter, were measured at baseline and after each treatment. RESULTS: Estradiol reduced LDL levels and increased high density lipoprotein (HDL) and triglycerides. P abolished these changes, whereas MPA only reversed the increase of HDL. Estradiol protected LDL from oxidation in a dose-dependent manner, although only at pharmacological concentrations (1 microM or higher). Both P and MPA were inert at either physiological or pharmacological concentrations. The size of the LDL particles remained unaffected except under MPA, in which it was reduced. CONCLUSIONS: Estradiol has a protective effect against LDL oxidation, although only at pharmacological dosages. P and MPA did not limit the E(2) action. The size of the LDL particles remained unaltered after each E(2) dose, but MPA, and not P, was associated with a diminution.
The rapid assessment of aerosols produced by medicinal inhalers is highly desirable from several standpoints, including the assurance of product quality, the development of new delivery systems, and the need to meet an increasing requirement by regulatory bodies for reliable in vitro performance data. Particle size analysis has traditionally been undertaken by cascade impactor on account of the direct assessment of active pharmaceutical ingredient(s) (APIs) that is possible by this method. However, laser diffractometry is less labor-intensive, more rapid, and can be a less invasive procedure. The technique provides meaningful results; as long as precautions are taken to validate that the measurements are an accurate reflection of the distribution of API mass as a function of particle or droplet size. We begin the review by examining the underlying theory of the laser diffraction method. After a brief description of current laser diffractometers used in inhaler measurements, we continue by examining the range of applications by inhaler class. We then examine the basis upon which inhaler measurements made by laser-diffractometry can be compared with equivalent particle size distribution data from compendial techniques. We conclude the assessment of the technique by developing guidelines for its valid application as a component of the range of in vitro methods that are available for inhaler performance assessment.
An exponential distribution model was fitted to the particle size data of samples of digesta from sheep fed lucerne hay. It was best fitted to the oesophagus and rumen samples, which contain large particles, than to the duodenum and faeces samples.
In 1939 the author reported the results of measured refractive indices of about a hundred crystalline drugs listed in [JP V] at the Takeda Research Laboratory using a Leitz PM polarizing microscope and newly developed immersion oils. When the author had reopened the study of crystalline drugs using a polarizing microscope at the Kobe-Gakuin University starting from 1975 one of the main purposes was to clarify the relation between crystal habits and refractive indices. It had been found that in most cases of crystal habits refractive indices were uniquely measured from a predominant pair of faces forming superior the habit, and they were called as "key refractive indices". The author and his co-workers tried to investigate the possibility of measuring the key refractive indices widely from all the obtainable crystalline drugs listed in the [JP X] or [JP XI], co-operating with the Pharmacy of Kobe University Hospital. Thus, more than 170 kinds of crystalline drugs were tested for their key refractive indices and found that they were measured from about 60-70% of tested drugs. It was also clarified that the difference of 2 key refractive indices, (n2 - n1), the birefringence of the section, was also an unique invariable number for the habit, and it played an important role not only for the graphic representation of log(n2 - n1), abscissa, against (n1, n2), ordinate, for the sake of an analytical purpose but also to measure a thickness of a section (habit) using a retardation color. Then, it had been cleared that the similarity of crystal habits in the microscopic field was based on the facts of measuring the same key refractive indices, and the author had developed a chart for measuring key refractive indices as well as producing a 3 dimensional orthographic projection of a crystal habit simultaneously applying a thickness measuring method using a birefringence. Finally 3 dimensional parameter a, b, c of a crystal habit and "habit coefficients" T: square root of ab/c and L: b/c were determined from the orthographic projection. In conclusion using the similarity in crystal habits the distributions of particle sizes and specific surface areas of all the crystals in the microscopic field had been calculated by a personal computer putting in necessary habit coefficients and obtained data of parameter b. The relation between 2 dispersions of particle sizes in log (V) and specific surface areas in log (SSA) were shown under the rectangular coordinates log (V) on the abscissa and log (SSA) on the ordinate, where the loci of log (SSA) formed simple striped pattern composed of parallel straight lines depending on habit coefficients. It would be possible to estimate the value of a specific surface area of any crystalline substance by plotting the value of log (V) on the straight line of a locus of log (SSA) having the same habit coefficients.
Transgenic mice carrying the human apolipoprotein (apo) A-I gene (HuAITg mice) were used to examine the effects of overexpression of the human gene on high density lipoprotein (HDL) particle size distribution and metabolism. On a chow diet, control mice had HDL cholesterol and apo A-I levels of 49 +/- 2 and 137 +/- 12 mg/dl of plasma, respectively. HuAITg mice had HDL cholesterol, human apo A-I, and mouse apo A-I levels of 88 +/- 2, 255 +/- 19, and 16 +/- 2 mg/dl, respectively. Nondenaturing gradient gel electrophoresis revealed control mouse plasma HDL to be primarily monodisperse with a particle diameter of 10.2 nm, whereas HuAITg mouse plasma HDL was polydisperse with particles of diameter 11.4, 10.2, and 8.7 nm, which correspond in size to human HDL1, HDL2, and HDL3, respectively. In vivo turnover studies of HDL labeled with [3H]cholesteryl linoleyl ether (representing the cholesteryl ester pool) and 125I-apo A-I were performed. In control animals, the fractional catabolic rate (FCR) for HDL cholesteryl ester (0.197 +/- 0.010 pool/hr) was significantly (P less than 0.0005) more than the apo A-I FCR (0.118 +/- 0.006 pool/hr). In the HuAITg mice, the HDL cholesteryl ester FCR (0.124 +/- 0.008 pool/hr) was the same as the apo A-I FCR (0.126 +/- 0.010 pool/hr). There were no significant differences between control and HuAITg animals in the sites of tissue removal of HDL cholesteryl ester, with the liver extracting most of the injected radioactivity. Control and HuAITg animals had comparable liver and intestinal cholesterol synthesis and LDL FCR. In conclusion, HuAITg mice have principally human and not mouse apo A-I in their plasma. This apparently causes a change in HDL particle size distribution in the transgenic mice to one resembling the human pattern. The replacement of mouse by human apo A-I also apparently causes the loss of the selective uptake pathway of HDL cholesteryl esters present in control mice. These data imply that apo A-I primary structure has a profound influence on HDL particle size distribution and metabolism.
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The relationship between low-density lipoprotein (LDL) peak particle diameter and insulin sensitivity, very-low-density lipoprotein (VLDL) + intermediate-density lipoprotein (LDL) triglyceride, cholesterol, and apoprotein B, postprandial lipemia, and LDL + high-density lipoprotein (HDL) triglyceride was assessed. The subjects were 101 healthy males aged 15 to 45 years. Sixty-one subjects (60.4%) were offspring of a parent with coronary artery disease before age 60, and 40 subjects (39.6%) had no parental history of coronary artery disease. LDL peak particle diameter was measured following polyacrylamide gradient gel electrophoresis. An insulin sensitivity index (Si) was determined from a frequently sampled intravenous glucose tolerance test using a minimal modeling method. A fat tolerance test was performed with a test meal containing 70 g/m2 fat, with triglyceride concentrations measured hourly for 12 hours. LDL peak particle diameter was significantly correlated with body mass index (BMI) (r = -.282, P < .01), waist to hip ratio (r = -.291, P < .01), fasting triglyceride (logarithmically [log] transformed) (r = -.566, P < .001), area under the postprandial triglyceride curve (log transformed) (r = -.562, P < .001), VLDL + IDL triglyceride (log transformed) (r = -.462, P < .001), VLDL + IDL cholesterol (log transformed) (r = -.477, P < .001), VLDL + IDL apoprotein B (log transformed) (r = -.321, P < .001), LDL + HDL triglyceride (log transformed) (r = .583, P < .001), and HDL cholesterol (r = .347, P < .001), but there was no significant correlation with Si. Using stepwise regression analysis, LDL + HDL triglyceride showed the strongest relationship to LDL peak particle diameter, accounting for 34% of the variation in size. Si was not an independent predictor of LDL particle size. In conclusion, insulin sensitivity appears to have little influence on LDL particle size. The importance of LDL + HDL triglyceride should be considered a preliminary finding warranting verification in this and other populations.
A 2(3) factorial arrangement of treatments was used to study main effects and interactions between particle size of prairie hay (chopped vs ground), two levels of feed intake (60 and 90% of ad libitum) and ruminal degradability of protein sources [dry corn gluten feed (DCGF) vs dry distillers grains (DDG)] on ruminal and total tract digestion in eight ruminal- and duodenal-cannulated steers. Steers were fed every 2 h to approach steady-state feeding conditions. Steers fed ground hay diets digested higher (P less than .05) percentages of total digestible organic matter (OM) and neutral detergent fiber (NDF) in the rumen and had lower (P less than .05) nonammonia-nonbacterial N (NANBN) flows to the duodenum than did those fed chopped hay, probably because greater surface area of ground hay allowed more extensive ruminal fermentation. Protein source X intake interactions were noted for ruminal OM and NDF digestion when expressed as percentages of total digestion. At low intakes, steers fed DCGF had higher (P less than .05) percentages of total digestible OM and NDF disappearing in the rumen than did those fed DDG. Steers fed DCGF had lower total N, NANBN and total amino acid (AA) flows at the duodenum than did those fed DDG, indicating that less DCGF protein escaped ruminal degradation. Steers fed DDG had greater (P less than .05) total tract NDF digestion, suggesting that escape protein from DDG may stimulate hindgut fermentation and thereby affect site and extent of nutrient digestion. Regression analysis indicated that extent of ruminal fermentation and efficiency of microbial growth in vivo are associated with ruminal rates of passage within individual animals. When steers were fed at high-intake levels (1.6% of body weight), ruminal dilution rates were not increased (P less than .05) due to forage particle size or level of intake treatments, accounting, in part, for the lack of expected treatment differences in efficiency of bacterial growth and duodenal N flow, and for the low number of interactions between main effects.
The effect of particle size on the reactivity of hexyltrimethoxysilane (C6S) with the particle surface was studied by using silica nanoparticles (SNPs) with different diameters (30 or 200 nm). In case of 30-nm SNPs, a large amount of isolated silanol was observed. On the other hand, in the case of 200-nm SNPs, the amount of hydrogen bonded silanol and hydrogen bonded water molecules at the surface of the SNPs increased. Since the hydrogen bonded silanol and the hydrogen bonded water enhanced the reaction of C6S with SNPs, the chemisorbed C6S on 200-nm SNPs was larger than that on 30-nm SNPs. Furthermore, the effects of surface modification on the dispersion stability in MEK were studied using viscosity measurements and surface force measurements by the AFM colloid probe method. The viscosity of the dilute SNPs/MEK suspension did not change by the chemisorptions of C6S; however, the viscosity of dense suspension reduced effectively by surface modification. It was estimated that the suspension viscosity reduced effectively when the mean particle surface distance in the suspension was near to the distance where the repulsive force appeared by the surface force measurements using the colloid probe AFM.
OBJECTIVES: We sought to determine whether endothelial vasodilator function (EVF) in patients with type 1 diabetes was related to low-density lipoprotein (LDL) particle size (LDLPS), LDL vitamin E content (LDLVE) or the susceptibility of LDL to oxidation (OxLDL). BACKGROUND: Impaired EVF is an early feature of diabetic vascular disease and may be related to oxidant stress. Although small, dense LDL and oxidized LDL are features of type 2 diabetes and predict the development of coronary artery disease, their role in type 1 diabetes is less clear. METHODS: Endothelium-dependent vasodilation was assessed in the brachial artery (flow-mediated vasodilation [FMD]) and in the forearm resistance circulation using venous occlusion plethysmography in response to graded doses of intrabrachial acetylcholine (ACh). Thirty-seven patients with type 1 diabetes mellitus (DM) and 45 matched controls underwent flow-mediated dilation, while a subset of 19 DM and 20 controls underwent plethysmography. RESULTS: Total, LDL and high-density lipoprotein cholesterol or triglycerides were not different in DM compared with controls, but LDLPS was smaller (25.6 +/- 0.06 vs. 26.1 +/- 0.1 nm, p < 0.05) and LDLVE was reduced (2.0 +/- 0.25 vs. 2.6 +/- 0.18 micromol/mmol LDL, p < 0.05). Oxidative susceptibility of LDL was not different. Flow-mediated vasodilation was impaired in DM compared with controls (3.6 +/- 0.6% vs. 7.1 +/- 0.5%, p < 0.005), as was the vasodilator response to ACh (p < 0.05). Flow-mediated vasodilation was directly related to LDLPS and LDLVE in both the entire study cohort and DM alone (p < 0.05), but not to other parameters of the standard lipid profile. Similarly, endothelium-dependent vasodilation in the resistance circulation was directly related to LDLPS and LDLVE, but not to OxLDL. CONCLUSION: These results suggest, but do not prove, that LDL particle size and LDL vitamin E may be determinants of conduit and resistance vessel endothelial vasodilator function in type 1 diabetes. Further work will be required to prove cause and effect.
Eighteen Holstein heifers were fed long and chopped coarse and fine alfalfa hay ad libitum to evaluate effects of physical form on digestion and chemical composition of feed and fecal particles and to examine the applicability of a sinusoidal model to chewing behavior. Recordings of jaw movement were divided into 1-h segments for analysis. Least square mean size of fecal particles from coarse and finely chopped diets were 290 and 297 micrometers as compared to 227 micrometers on long hay. Intakes of dry matter were greater an digestibilities lower for chopped as compared to long hay. Crude protein content of separated feed and fecal particles increased as particle size decreased. Neural and acid detergent fiber concentrations decreased in feed and feces with decreasing particle size. Lignin content of feed particles decreased as particle size decreased, whereas for fecal particles lignin as a percent of cell wall followed a "U" shaped pattern of declining then increasing as size decreased. Patterns were sinusoidal for eating and ruminating long and chopped hays and total chewing (eating and ruminating) of long hay. Our results suggest a gradual effect on chemical degradation and physical detrition of digesta particles and chewing behavior as forage particle size decreased.
To estimate the particle size of hepatitis C virus (HCV), a major causative agent of post-transfusion non-A, non-B hepatitis, we filtered plasma or serum samples through microporous cellulose fibres with different pore sizes. The amount of HCV particles in samples before and after filtration was determined by a quantitative reverse transcriptase polymerase chain reaction (PCR) method. Since there is no quantitative biological assay for HCV, except for that in chimpanzees, the HCV titre obtained from the PCR method was used in an equation constructed previously for application to filtration experiments with a flavivirus which is distantly related to HCV. The particle was estimated to be between 30 and 38 nm in diameter, although the possibility remained that larger HCV particles or HCV aggregates with a diameter of more than 39 nm might exist. Double-step filtration through microporous cellulose fibres with a pore size of 35 nm reduced the HCV content to below levels detectable by our PCR method, indicating that it is possible to eliminate HCV particles by simple filtration techniques.
OBJECTIVE: To investigate effect of particle size on oral absorption of silymarin-loaded solid lipid nanoparuicles. METHOD: Solid lipid nanoparticles (SLN) of various sizes (150 nm, 500 nm and 1000 nm) using Compritol 888 ATO as the material and silymarin (SM) as a model drug were prepared. Silybinin concentration in plasma of rats were determined by RP-HPLC with UV detector. The main pharmacokinetic parameters were calculated by 3p97. RESULT: Results showed that the AUC of 150 nm SLN was 2.08 fold that of 500 nm SLN and 2.54 fold of 1000 nm SLN treated orally to rats (P < 0.05). The oral bioavailability of 150 nm SLN was remarkably higher than the other two size SLN. CONCLUSION: This has important implications in designing of SM-SLN as a new oral drug delivery system.
Suppositories of chlorphenamine maleate were formulated. The influence of particle size and percentage concentration of chlorphenamine maleate on the physical standards of its suppositories as well as the release of the drug from oily base (cacao butter), water-soluble base (carbowax) and emulsifying base (Witepsol) has been investigated.
The X-ray diffraction method and the phosphoric acid method are widely used to determine the fraction of free silica (mainly quartz and other silica polymorphs) in respirable dust sampled in working environments in Japan. In this study, we clarified the size effect of quartz dust for the X-ray diffraction method and the phosphoric acid method using size controlled quartz samples. The quartz samples were classified into 6 fractions with different size ranges: 1 microm and smaller, 1 to 3 microm, 3 to 5 microm, 5 to 7 microm, 7 to 10 microm and 10 microm and larger. Both of the determination methods were affected by the particle size, and especially particles smaller than 3 microm fairly dissolved in hot phosphoric acid and reduced X-ray diffraction intensity remarkably. If the content of these fine particles in the standard quartz sample is lower than that of the test samples, the fraction of free silica may be underestimated by these methods. For this reason, the standard quartz sample should have a representative size distribution of the field samples. The dust samples containing quartz were collected at a foundry and dissolved by phosphoric acid to remove non-quartz materials. The size fractions of dissolved samples were 50% for 5-10 microm, 25% for 3-5 microm, 20% for 1-3 microm and 5% for 1 microm and smaller. As the size distribution is similar to the present standard sample widely used in Japan, we concluded that the standard sample is suitable for these determination methods.
Soil structure depends on the association between mineral soil particles (sand, silt, and clay) and organic matter, in which aggregates of different size and stability are formed. Although the chemistry of organic materials, total microbial biomass, and different enzyme activities in different soil particle size fractions have been well studied, little information is available on the structure of microbial populations in microhabitats. In this study, topsoil samples of different fertilizer treatments of a long-term field experiment were analyzed. Size fractions of 200 to 63 microm (fine sand fraction), 63 to 2 microm (silt fraction), and 2 to 0.1 microm (clay fraction) were obtained by a combination of low-energy sonication, wet sieving, and repeated centrifugation. Terminal restriction fragment length polymorphism analysis and cloning and sequencing of 16S rRNA genes were used to compare bacterial community structures in different particle size fractions. The microbial community structure was significantly affected by particle size, yielding higher diversity of microbes in small size fractions than in coarse size fractions. The higher biomass previously found in silt and clay fractions could be attributed to higher diversity rather than to better colonization of particular species. Low nutrient availability, protozoan grazing, and competition with fungal organisms may have been responsible for reduced diversities in larger size fractions. Furthermore, larger particle sizes were dominated by alpha-Proteobacteria, whereas high abundance and diversity of bacteria belonging to the Holophaga/Acidobacterium division were found in smaller size fractions. Although very contrasting organic amendments (green manure, animal manure, sewage sludge, and peat) were examined, our results demonstrated that the bacterial community structure was affected to a greater extent by the particle size fraction than by the kind of fertilizer applied. Therefore, our results demonstrate specific microbe-particle associations that are affected to only a small extent by external factors.
It has previously been observed that after the third decade of life the tensile strength of bone decreases faster than its density [1], indicating that some microstructural change occurs in bone with advancing age. In order to try to elucidate this observation, the orientation and particle size of the mineral phase of bone have been studied with respect to age. Samples were taken from femora varying in age from 13 to 97 years. The results show that the degree of preferred orientation does not vary with age after the first decade of life. However, the percentage of small particles increased up to the fourth decade of life and thereafter decreased, a pattern of change similar to that observed for bone strength. It would seem to indicate that an increase in mineral particle size is a factor that contributes to the loss of bone strength and that an increased percentage of bone strength and that an increased percentage of large particles in the later years of life could, along with osteoporosis, help to explain the increased fragility in the bones of the elderly.