ABSTRACT
Usage of forward osmosis membrane in FO mode, in which active and support layers of the membrane were in contact with the feed and the draw solutions respectively, provided higher initial water flux (12L/m2h) than the usage of membrane in PRO mode (6L/m2h) having opposite orientation but fluxes approached to each other after 4h during concentration of whey with NH3/CO2 as draw salt. High organic and inorganic foulants of whey was considered as reason for observed result in addition to lower solute resistivity. Initial water flux (8,5L/m2h) was lower when pre-treatment was applied before forward osmosis process but final flux (4L/m2h) was equal flux of non pre-treatment. Reduction of solute resistivity or absence of hydraulic pressure can be reasons for lower initial flux. Detection of organic carbon but absence of lactose in draw solution showed passage of molecules being different than lactose into draw solution.
Subject(s)
Water Purification , Whey , Membranes, Artificial , Osmosis , SolutionsABSTRACT
Nanoparticles prepared from human serum albumin (HSA) are versatile carrier systems for drug delivery and can be prepared by an established desolvation process. A reproducible process with a low batch-to-batch variability is required for transfer from the lab to an industrial production. In the present study the batch-to-batch variability of the starting material HSA on the preparation of nanoparticles was investigated. HSA can build dimers and higher aggregates because of a free thiol group present in the molecule. Therefore, the quality of different HSA batches was analysed by size exclusion chromatography (SEC) and analytical ultracentrifugation (AUC). The amount of dimerised HSA detected by SEC did not affect particle preparation. Higher aggregates of the protein detected in two batches by AUC disturbed nanoparticle formation at pH values below 8.0. At pH 8.0 and above monodisperse particles between 200 and 300 nm could be prepared with all batches, with higher pH values leading to smaller particles. Besides human derived albumin a particle preparation was also feasible based on recombinant human serum albumin (rHSA). Under comparable preparation conditions monodisperse nanoparticles could be achieved and the same effects of protein aggregates on particle formation were observed. For nanoparticulate drug delivery systems the enzymatic degradation is a crucial parameter for the release of an embedded drug. For this reason, besides the particle preparation process, particle degradation in the presence of different enzymes was studied. Under acidic conditions HSA as well as rHSA nanoparticles could be digested by pepsin and cathepsin B. At neutral pH trypsin, proteinase K, and protease were suitable for particle degradation. It could be shown that the kinetics of particle degradation was dependent on the degree of particle stabilisation. Therefore, the degree of particle stabilisation will influence drug release after cellular accumulation of HSA nanoparticles.
Subject(s)
Nanoparticles/chemistry , Peptide Hydrolases/chemistry , Serum Albumin/chemistry , Cathepsin B/chemistry , Drug Compounding/methods , Glutaral/chemistry , Humans , Hydrogen-Ion Concentration , Kinetics , Molecular Weight , Particle Size , Pepsin A/chemistry , Peptide Hydrolases/metabolism , Recombinant Proteins/chemistry , Recombinant Proteins/metabolism , Reproducibility of Results , Serum Albumin/genetics , Serum Albumin/metabolism , Static Electricity , Surface Properties , Trypsin/chemistryABSTRACT
The aim of this study was to investigate the presence of A-waves in cases referred to our electromyography laboratory with various diagnoses and documentation of electrophysiologic diagnoses with A-waves. In cases where at least 3 motor nerves were analysed, during F response studies, A-waves having stabile latencies and amplitudes from minimum one third of submaximal and supramaximal stimuli were evaluated. Electrophysiologic diagnoses and the related nerves of cases with A-waves were recorded. A-waves were obtained from 38 out of 1604 cases (2.36%). Most of the cases (57.8%) with established A-waves consisted of patients with radiculopathies. A-waves were detected mostly in tibial nerve. Electrophysiologic analysis of 5 cases with A-waves has given normal results. Although mechanism of A-waves is not known completely, we suggest when obtained it must be remarked during routine electrophysiologic examination.
