Steinernema jeffreyense n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from South Africa.

During a non-targeted survey for entomopathogenic nematodes in South Africa, a new species of Steinernema was isolated from a soil sample collected from underneath a guava tree, close to the shore at Jeffrey's Bay. The nematode was isolated by means of the insect-baiting technique using last-instar larvae of Galleria mellonella. It is described herein as Steinernema jeffreyense n. sp. The nematode can be separated from other described, closely related species in terms of the morphological and morphometric characteristics of the different life stages, and in terms of the characterization and phylogeny of DNA sequences of the internal transcribed spacer (ITS) rDNA of the 18S gene, and of the D2D3 region of the 28S rDNA gene. The new species is placed molecularly in the arenarium-glaseri-karii-longicaudatum group characterized by the following morphological characters: infective third-stage juvenile with a body length of 926 (784-1043) µm, distance from head to excretory pore of 87 (78-107) µm, tail length of 81 (50-96) µm, with an E% of 109 (86-169), and eight evenly spaced ridges (i.e. nine lines) in the middle of the body. First-generation males have a spicule length of 88 (79-95) µm and gubernaculum length of 57 (51-61) µm. Male mucron is absent in both generations. First-generation females have an asymmetrical protuberance and a short, double-flapped epiptygmata, with both flaps directed to the front. The tail of the first-generation female is shorter than the anal body width, with a mucron on the dorsal tail tip, with D% = 78 (59-99). Cross-hybridization with S. khoisanae, S. tophus and S. innovationi showed the new species to isolate reproductively from the others. The analyses of ITS rDNA and D2D3 sequence of the 18S and 28S rDNA genes support the studied nematode isolate to be a valid new species belonging to the 'glaseri' group (Clade V).

Increased dissolution and physical stability of micronized nifedipine particles encapsulated with a biocompatible polymer and surfactants in a wet ball milling process.

Suspensions of nifedipine, a practically water-insoluble drug, were prepared in the presence of a biocompatible polymer, polyvinylpyrrolidone (PVP, K value 17), and three surfactants, sodium lauryl sulfate (SLS, anionic), cetyltrimethylammonium bromide (CETAB, cationic), polysorbate 80 (Tween 80, nonionic), by wet milling in ceramic ball mills. Nifedipine powders encapsulated with PVP and the surfactants were recovered from the suspensions after milling and evaluated for changes in particle size, morphology, sedimentation rate in aqueous suspensions, crystal form, and dissolution. Particle size analysis indicated that milling of suspensions in solutions of PVP and surfactants is an efficient method for reducing the particle size of nifedipine to below 10 microm. Furthermore, DSC and XPS analysis indicated that during milling the nifedipine crystals were coated with the PVP or surfactants and that milling with PVP stabilized the nifedipine crystal form during milling while nifedipine was gradually amorphisized when milled in a quaternary nifedipine/PVP/SLS/CETAB system. The decrease in particle size caused a significant decrease in sedimentation rate and increased the dissolution rate of nifedipine in simulated gastric fluid when compared to milled nifedipine and powder mixtures of the drug and the excipients.

Characterization of the solubility and dissolution properties of several new rifampicin polymorphs, solvates, and hydrates.

Based on reports that tuberculosis is on the increase, this investigation into the physicochemical properties of rifampicin when recrystallized from various solvent systems was undertaken. Rifampicin is an essential component of the currently recommended regimen for treating tuberculosis, although relatively little is known about its solubility and dissolution behavior in relation to its solid-state properties. A rifampicin monohydrate, a rifampicin dihydrate, two amorphous forms, a 1:1 rifampicin:acetone solvate, and a 1:2 rifampicin:2-pyrrolidone solvate were isolated and characterized using spectral, thermal, and solubility measurements. The crystal forms were relatively unstable because except for the 2-pyrrolidone solvate, all the hydrated or solvated materials changed to amorphous forms after desolvation. Fourier transform infrared (FTIR) analysis confirmed the favorable three-dimensional organization of the pharmacophore to ensure antibacterial activity in all the crystal forms except the 2-pyrrolidone solvate. In the 2-pyrrolidone solvate, the strong IR signals of 2-pyrrolidone interfered with the vibrations of the ansa group. The 2-pyrrolidone solvate was the most soluble in phosphate buffer at pH 7.4. This solvate also had the highest solubility (1.58 mg/ml) and the fastest dissolution in water. In 0.1 M HCl, the dihydrate dissolved the quickest. A X-ray amorphous form (amorph II) was the least soluble and had the slowest dissolution rate because the powder was poorly wettable and very electrostatic.