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Median Diameter (median + diameter)
Selected AbstractsEndoscopic ultrasound of pancreatic cystic lesionsANZ JOURNAL OF SURGERY, Issue 9 2010Shyam Prasad Abstract Background:, The impact of endoscopic ultrasonography (EUS) on the management of pancreatic cystic lesions remains unclear, and there are no published studies of the Australian experience in this area. The aim of this study was to review the experience of EUS for such lesions within our institution. Methods:, A retrospective review was undertaken of data collected prospectively over a two-year period within the EUS database of St. Vincent's Hospital. Patients who underwent EUS for suspected pancreatic cystic lesions were identified. Data were collected on demographic variables, EUS findings, the results of EUS-guided fine-needle aspiration (FNA) and the findings on clinical and radiological follow-up. Results:, Fifty-nine patients were identified. Two thirds were female. Most lesions were located at the pancreatic head. Median diameter was 25 mm. FNA was performed in 36 cases (61%). On cytology, six (17%) showed features of mucinous tumours and five (14%) showed adenocarcinoma. The remainder contained either non-specific benign cells or insufficient epithelial tissue. Follow-up data on 48 cases (83%), after a median duration of 15 months, revealed that 15 lesions (31%) had been resected, including six serous and six mucinous tumours. The level of carcinoembryonic antigen in FNA specimens appeared to be higher in mucinous than in serous neoplasms. Twenty-four lesions had undergone repeat radiological imaging: only three had grown in size. Conclusions:, EUS and FNA are useful procedures for assessing pancreatic cystic lesions. Malignant features are demonstrated in only a small minority. The majority of the remainder show no signs of progression during follow-up. [source] The effect of drawdown on suspended solids and phosphorus export from Columbia Lake, Waterloo, CanadaHYDROLOGICAL PROCESSES, Issue 5 2004Mike Shantz Abstract This study examines the effect of drawdown on the timing and magnitude of suspended solids and associated phosphorus export from a 12 ha reservoir located in an urbanized watershed in southern Ontario, Canada. Water level in Columbia Lake was lowered by 1·15 m over a 2-week period in November 2001. The total phosphorus (TP) concentrations ranged from 63 to 486 µg L,1 in Columbia Lake and 71 to 373 µg L,1 at its outflow. All samples exceeded the Provincial Water Quality Objective of 30 µg TP L,1. Outflow concentrations of suspended solids and TP increased significantly with decreasing lake level and were attributed to the resuspension of cohesive bottom sediments that occurred at a critical threshold lake level (0·65 m below summer level). Suspended solids at the outflow consisted of flocculated cohesive materials with a median diameter (D50) of c. 5 µm. Particulate organic carbon accounted for 8·5% of the suspended solids export by mass. A total mass of 18·5 t of suspended solids and 62·6 kg TP was exported from Columbia Lake, which represents a significant pulse of sediment-associated P to downstream environments each autumn during drawdown. The downstream impacts of this release can be minimized if the water level in Columbia Lake is lowered no more than 0·5 m below summer levels. Copyright © 2004 John Wiley & Sons, Ltd. [source] Effect of particle size of an amorphous calcium phosphate filler on the mechanical strength and ion release of polymeric composites,JOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Soo-Young Lee Abstract The random clustering of amorphous calcium phosphate (ACP) particles within resin matrices is thought to diminish the strength of their polymerized composites. The objective of this study was to elucidate the effect of ball-milling on the particle size distribution (PSD) of ACP fillers and assess if improved dispersion of milled ACP in methacrylate resin sufficiently enhanced filler/matrix interactions to result in improved biaxial flexure strength (BFS), without compromising the remineralizing potential of the composites. Unmilled and wet-milled zirconia-hybridized ACP (Zr-ACP) fillers were characterized by PSD analysis, X-ray diffraction, thermogravimetric and chemical analysis, infrared spectroscopy, and scanning electron microscopy. Composite specimens made from a photoactivated, ternary methacrylate resin admixed with a mass fraction of 40% of un-milled or milled Zr-ACP were evaluated for the BFS (dry and wet) and for the release of calcium and phosphate ions into saline solutions. While having no apparent effect on the structure, composition, and morphology/topology of the fillers, milling significantly reduced the average size of Zr-ACP particulates (median diameter, dm = 0.9 ± 0.2 ,m) and the spread of their PSD. Better dispersion of milled Zr-ACP in the resins resulted in the improved BFS of the composites, even after aqueous soaking, and also gave a satisfactory ion release profile. The demonstrated improvement in the mechanical stability of anti-demineralizing/remineralizing ACP composites based on milled Zr-ACP filler may be beneficial in potentially extending their dental utility. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] An investigation into the mechanism of dissolution rate enhancement of poorly water-soluble drugs from spray chilled gelucire 50/13 microspheresJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2010Sheng Qi Abstract The production and physicochemical characterisation of spray chilled Gelucire 50/13 microspheres is described with a view to improving the dissolution of a poorly water-soluble drug, piroxicam, and understanding the fundamental mechanisms associated with the improved drug release. Thermorheological testing was developed as a fast screening method for predicting the processability of dispersions for spray chilling preparation. Spray chilled piroxicam loaded microspheres were spherical in shape with a median diameter of circa 150,µm. DSC indicated no interaction between piroxicam and lipid matrix, while HSM studies performed in polarized light mode indicated that the spheres contained distinct drug crystals. Polarising light microscopy and small-angle XRD investigations on the hydration behaviour of the lipid and the spray chilled microspheres revealed the formation of liquid crystalline phases depending on the degree of hydration. The dissolution behaviour of the piroxicam loaded microspheres showed significant improvements compared to drug alone. The particle size, drug loading and aging of the microspheres were all found to have an influence on the release behaviour. It was proposed that Gelucire 50/13 microspheres release the entrapped piroxicam via formation of a lyotropic liquid crystalline phase, which allows dissolution of the drug particles in a finely divided, high surface area and well-wetted state. © 2009 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 99:262,274, 2010 [source] Comparison of particle sizing techniques in the case of inhalation dry powdersJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2001Cynthia Bosquillon Abstract The objectives of this work were (i) to validate electrical zone sensing and laser diffraction for the analysis of primary particle size in the case of inhalation dry powders and (ii) to study the influence of the aggregation state of the powder on the sizing techniques. Free-flowing dry powders were prepared by spray-drying with a combination of albumin, lactose, and dipalmitoylphosphatidylcholine. The replacement of lactose by mannitol, the removal of albumin, and the atomization at high relative humidity all increased powder cohesion. Automated measurements were compared with primary particle sizes collected by light and electron microscopy. The mass mode obtained by electrical zone sensing and the mass median diameter measured by laser diffraction following dispersion with compressed air at a pressure of 3 bar or following suspension in water and ultrasonic dispersion at a power of 60 W for 30 s each provided primary particle sizes close to microscopy measurements. However, these conditions only applied in the case of slightly to moderately aggregated powders. For strongly agglomerated powders, an exact measurement of the size was only collected by laser diffraction in the wet state combined with ultrasonic dispersion. Our study underlies how measurement of primary particle size highly depends on both powder material and proper particle dispersion. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:2032,2041, 2001 [source] Formulations generated from ethanol-based proliposomes for delivery via medical nebulizersJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 7 2006Abdelbary M. A. Elhissi Multilamellar and oligolamellar liposomes were produced from ethanol-based soya phosphatidylcholine proliposome formulations by addition of isotonic sodium chloride or sucrose solutions. The resultant liposomes entrapped up to 62% of available salbutamol sulfate compared with only 1.23% entrapped by conventionally prepared liposomes. Formulations were aerosolized using an air-jet nebulizer (Pari LC Plus) or a vibrating-mesh nebulizer (Aeroneb Pro small mesh, Aeroneb Pro large mesh, or Omron NE U22). All vibrating-mesh nebulizers produced aerosol droplets having larger volume median diameter (VMD) and narrower size distribution than the air-jet nebulizer. The choice of liposome dispersion medium had little effect on the performance of the Pari nebulizer. However, for the Aeroneb Pro small mesh and Omron NE U22, the use of sucrose solution tended to increase droplet VMD, and reduce aerosol mass and phospholipid outputs from the nebulizers. For the Aeroneb Pro large mesh, sucrose solution increased the VMD of nebulized droplets, increased phospholipid output and produced no effect on aerosol mass output. The Omron NE U22 nebulizer produced the highest mass output (approx. 100%) regardless of formulation, and the delivery rates were much higher for the NaCl-dispersed liposomes compared with sucrose-dispersed formulation. Nebulization produced considerable loss of entrapped drug from liposomes and this was accompanied by vesicle size reduction. Drug loss tended to be less for the vibrating-mesh nebulizers than the jet nebulizer. The large aperture size mesh (8,m) Aeroneb Pro nebulizer increased the proportion of entrapped drug delivered to the lower stage of a twin impinger. This study has demonstrated that liposomes generated from proliposome formulations can be aerosolized in small droplets using air-jet or vibrating-mesh nebulizers. In contrast to the jet nebulizer, the performance of the vibrating-mesh nebulizers was greatly dependent on formulation. The high phospholipid output produced by the nebulizers employed suggests that both air-jet and vibrating-mesh nebulization may provide the potential of delivering liposome-entrapped or solubilized hydrophobic drugs to the airways. [source] Measuring the filtration performance of breathing system filters using sodium chloride particles*ANAESTHESIA, Issue 2 2002apparatus The filtration performance of 33 breathing system filters (nine pleated hydrophobic and 24 electrostatic filters) was measured using sodium chloride particles. The particles had a size distribution with a count median diameter of 0.07 µm and a geometric standard deviation not exceeding 1.83. The geometric mean penetration values ranged from 0.002 to 0.67% for the nine pleated hydrophobic filters and from 0.25 to 35% for the 24 electrostatic filters (p <,0.0001 for the difference between the two filter types). The filtration performance obtained when filters are challenged with either sodium chloride particles or microbes is compared and discussed. [source] Role of epidermal growth factor receptor (EGFR) in corneal remodelling in diabetesACTA OPHTHALMOLOGICA, Issue 8 2009Saeed Akhtar Abstract. Purpose:, This study examined the role of epidermal growth factor receptor (EGFR) signalling on the organization and remodelling of collagen fibrils (CFs) and proteoglycans (PGs) in the stroma of diabetic rat cornea. Methods:, Diabetes was induced in female Wistar rats (n = 5) by streptozotocin (STZ) injection (55 mg/kg). Treatment with a selective inhibitor of EGFR tyrosine kinase, AG1478, was started on the same day as the induction of diabetes and administered every other day for 4 weeks. Corneas were fixed in 4% paraformaldehyde at 4 ° to allow for analysis of CF diameters and in 2.5% glutaraldehyde in sodium acetate buffer containing cuprolinic blue to enable the study of PG distribution. AnalySIS soft imaging software was used to analyse CFs and PGs. Results:, Epithelial thickness, and median diameter and area fraction of CF in corneal stroma were decreased in diabetic rat cornea compared with normal cornea (p < 0.001), whereas the median PG area and area fractions were significantly increased (p < 0.001). Treatment with AG1478, although it had no action on normal cornea, prevented these diameter and area fraction changes in CFs and PGs. The cornea of AG1478-treated diabetic rats showed a slight increase in CF diameter and area fraction and a decreased number density. Conclusions:, These data show that the distribution of corneal stroma CFs and PGs was altered after 4 weeks of diabetes and that, furthermore, treatment with an EGFR signalling inhibitor normalized these abnormalities. The data suggest that EGFR plays an important role in the development of diabetes-induced corneal remodelling. [source] 18 years experience of the use of proton beam in ophthalmic tumoursACTA OPHTHALMOLOGICA, Issue 2009L DESJARDINS Purpose Since 1991, more than 3000 patients were treated at Curie Institute by proton beam for uveal melanoma. All datas concerning tumor characteristics, treatment planning and follow up are registered in the data base Methods We have performed a retrospective review of patients treated before 2005. Patients were sent to Curie by their local ophtalmologist. Clip positioning and proton beam therapy with a dose of 60 grays in 4 fractions was scheduled; All patients were seen once a year in our clinic after treatment with liver ultrasounds twice a year. Results 2214 patients were treated, median age 61 years, median diameter 13,6 mm, median Thickness 4,7 mm. 20% of patients develloped metastasis,25% of patients died, 4% had local recurrences, 6,7% had secondary enucleations; With multivariate analysis Significant risk factors for metastasis were age (>60 ), tumor location, tumor diameter and tumor thickness( p<0,0001); Significant risk factor for local recurrence was tumor diameter (p<0,001) significant risk factor for secondary enucleation were tumor diameter (p<0,0001) and tumor thickness (p= 0,003) Neovascular glaucoma was 10% at 2years , 30% at 5 years and 34% at 10 years. Maculopathy was 40% at 2 years, 62% at 5 years and 66% at 10 years Optic neuropathy was 14% at 2 years, 29% at 5 years and 38% at 10 years At last follow up 36,2% of patients have more than 20/40 vision Conclusion Tumor control obtained by proton beam is excellent with a long follow up For big tumors news additional techniques like endoresections, additional TTT or antiVEGF could enhance globe preservation [source] Effect of citric acid and 1,2-dihydroxybenzene 3,5-disulfonic acid on crystallization of calcium sulfate dihydrate under simulated conditions of phosphoric acid productionCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2005M. M. Rashad Abstract The effect of citric acid and 1,2-dihydroxybenzene 3,5-disulfonic acid (DHBDSA), as additives, on the crystallization of gypsum was studied under simulated conditions of the of phosphoric acid production. Calcium hydrogen phosphate and sulfuric acid were mixed with dilute phosphoric acid at 80 °C, and the turbidity of the reaction mixture was measured at different time periods to calculate the induction time of gypsum crystals formation. Addition of citric acid increased the induction time and decreased the growth efficiency while addition of DHBDSA decreased the induction time and increased the growth efficiency compared with in absence of additives. The crystals mean and median diameters were found to decrease in the presence of citric acid and increased in the presence of DHBDSA. The surface energy decreased with citric acid and increased with DHBDSA compared to the baseline (without additives). Interestingly, the majority of the formed crystals are tabular with DHBDSA and needle-like type with citric acid and baseline [source] Effect of phosphonate additive on crystallization of gypsum in phosphoric and sulfuric acid mediumCRYSTAL RESEARCH AND TECHNOLOGY, Issue 12 2002H. El-Shall Abstract Understanding the mechanisms of growth and inhibition during crystallization of calcium sulfate is of primary importance for many industrial applications. For instance, inhibition of the crystallization process may be required to prevent scale formation in pipes, boilers, heat exchangers, reactors, reverse osmosis membrane surfaces, cooling water systems, secondary oil recovery utilizing water flooding techniques and desalination evaporators, etc. On the other hand, control growth and morphology of gypsum crystals is desired in achieving higher filtration rate and higher productivity of phosphoric acid from phosphate rocks. In this regard, this basic study is carried out to understand effect of Aminotris (methylenephosphonic acid (ATMP) on calcium sulfate dihydrate (gypsum) crystallization. The time elapsed between the achievement of supersaturation and the appearance of a solid phase (termed as induction time) is measured under different supersaturation ratios ranging from 1.018 to 1.979. The data are used to calculate the surface energy, critical nucleus size, and crystal growth rates of gypsum under different conditions. The results show that, the induction time decreases exponentially with increasing the supersaturation ratio. In addition, the surface energy decreases with ATMP compared to the baseline (without ATMP). Interestingly, with addition of the ATMP, the crystals mean and median diameters are found to decrease. The inhibition efficiency ranges from 16% to 59% depending on supersaturation ratio. [source] Aggregation Experiments on Fine Fly Ash Particles in a Gradient Magnetic FieldCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 8 2007W. Li Abstract Aggregation experiments were conducted on two kinds of fly ash particles in the size range of 0.023,9.314,,m in a gradient magnetic field produced by permanent magnetic rings. The two types of fly ash particles were obtained from Dongsheng and Datong coal combustion. The effect of particle size, total particle mass concentration, particle residence time in the magnetic field and gas velocity were examined. Experimental results showed that the removal efficiencies in a gradient magnetic field are much higher than those in a uniform magnetic field. The total and single-sized particle removal efficiencies can be improved by increasing the total particle mass concentrations and the particle residence time in the magnetic field or reducing the gas velocity. Mid-sized particle removal efficiencies are higher than those of the larger and smaller ones. With the increase in total particle removal efficiencies, the particle size corresponding to the maximum values of single-sized particle removal efficiencies and the particle number median diameters both decrease. Both the single-sized and total removal efficiencies for the particles from the Dongsheng coal combustion are higher than those from the Datong coal combustion. [source] | |||||||||||||