Practical technique to quantify small,dense low-density lipoprotein cholesterol using dynamic light scattering

Quantification of small, dense low-density lipoprotein (sdLDL) cholesterol is clinically significant. We propose a practical technique to estimate the amount of sdLDL cholesterol using dynamic light scattering (DLS). An analytical solution in a closed form has newly been obtained to estimate the weight fraction of one species of scatterers in the DLS measurement of two species of scatterers. Using this solution, we can quantify the sdLDL cholesterol amount from the amounts of the low-density lipoprotein cholesterol and the high-density lipoprotein (HDL) cholesterol, which are commonly obtained through clinical tests. The accuracy of the proposed technique was confirmed experimentally using latex spheres with known size distributions. The applicability of the proposed technique was examined using samples of human blood serum. The possibility of estimating the sdLDL amount using the HDL data was demonstrated. These results suggest that the quantitative estimation of sdLDL amounts using DLS is feasible for point-of-care testing in clinical practice.     

Stability of ZakianI MN recursions for linear delay differential equations

Long sequences of linear delay differential equations (DDEs) frequently occur in the design of control systems with delays using iterative-numerical methods, such as the method of inequalities. ZakianI _MN recursions for DDEs are suitable for solving this class of problems, since they are reliable and provide results to the desired accuracy, economically even if the systems are stiff. This paper investigates the numerical stability property of theI _MN recursions with respect to Barwell's concept ofP-stability. The result shows that the recursions using full gradeI _MN approximants areP-stable if, and only if,N−2≤M≤N−1.     

A general method for the preparation of 2-substituted-4-oxo-3-quinolinecarboxylic acids

A general method for preparing 2-substituted-4-oxo-3-quinolinecarboxylic acids and 2-substituted-4-oxo-1,8-naphthyridine-3-carboxylic acids as new analogs in the quinolone class of antiinfectives has been developed. The reaction of a Grignard reagent in the presence of copper(I) iodide with the 4-oxo-3-quinolinecar-boxylic acid esters and 4-oxo-1,8-naphthyridine-3-carboxylic acid esters yields the desired 2-substituent. Re-introduction of the 2,3-double bond is effected by phenylselenation of the 3-position, oxidation to the selen-oxide, and in situ syn-elimisation. Depending on the degree of steric crowding between the 2-substituent and the 3-carboxylic acid group, hydrolysis of the ester to the carboxylic acid could be carried out under acidic or basic conditions.     

The synthesis of methyl 1-aryl-2-pyrrolecarboxylates

A series of alkyl 1-(aryl)-2-pyrrolecarboxylates were prepared by the condensation of the appropriate aniline with methyl tetrahydro-2,5-dimethoxy-2-furancarboxylate in refluxing acetic acid. It was found that condensation proceeds even in substituents possessing steric bulk are present in the ortho positions of the aniline. Strong electron withdrawing substituents if conjugated to the nitrogen diverts the reaction from product to unidentified tars.     

Determination of gross alpha and beta activities in seawater and plankton from the Upper Gulf of Thailand

Gross alpha and beta activities were determined in seawater and plankton samples collected during the wet and dry seasons from 10 different sampling stations in Chonburi, the Upper Gulf of Thailand. Seawater samples were sampling, 1 km from the coastal and 2 m below the water surface, during July 2008 to July 2009. Seawater samples were prepared by coprecipitation technique. Plankton samples were prepared by filtration and dryness on filter paper. Both types of samples were counted using a low background alpha/beta proportional counter with multiple detector type (Berthold LB770). The results showed that gross alpha activities in seawater and plankton sample are in the range of 0.0591 ± 0.0209–0.3914 ± 0.0606 Bq/l and 0.0029 ± 0.0020–0.0294 ± 0.0043 Bq/l, respectively and also showed the lowest and highest activity level in the same sampling time. The activities of gross beta in seawater and plankton sample are in the range of 0.2803 ± 0.0177–1.3064 ± 0.0319 Bq/l and 0.0208 ± 0.0123–0.9151 ± 0.0262 Bq/l, respectively. Minimum detectable activity (MDA) had been observed in the measurements. The MDA of seawater sample were estimated to be 0.0832 Bq/l for alpha and 0.0577 Bq/l for beta at counting time of 100 and 200 min, respectively. In plankton samples, the MDA were estimated to be 0.0053 Bq/l for alpha and 0.0409 Bq/l for beta at the same counting time of 250 min.