Preparation Of Stock Solutions Research Articles

ENCAPSULATION OF FISH OIL IN SOLID ZEIN PARTICLES BY LIQUID-LIQUID DISPERSION

ABSTRACT In this work, a liquid–liquid dispersion process was studied for encapsulation of fish oil in solid zein particles as an alternative to emulsions. The process involved the preparation of stock solutions by dissolving different amounts (4.0, 5.3, and 6.7%) of zein and fish oil (zein: oil ratios of 2:1, 4:1, 6:1, and 8:1) in 90% isopropanol. The stock solution was then subsequently sheared into deionized water. The decrease of overall isopropanol concentration resulted in the precipitation of oil-loaded zein particles with diameters of 350–450 nm. After freeze-drying, samples with a zein – oil ratio of 4:1 or lower – generally showed good oxidative stability evaluated based on the development of lipid hydroperoxide values during storage. The approach used in this work may provide a simple method to prepare submicrometer-sized solid particles, and can be extended to encapsulate other types of lipophilic bioactive compounds. PRACTICAL APPLICATIONS Fish oil is conventionally included as the oil phase of emulsions that can be further prepared into powdered products. Emulsions of fish oil require both physical stability to eliminate destabilization mechanisms of emulsions and oxidative stability to prevent degradation of fish oil. The liquid–liquid dispersion process may be a simple, scalable approach to produce solid submicrometer particles for incorporation of lipophilic bioactive compounds as alternative delivery systems to emulsions. Solid particles may be incorporated in food products such as beverages, snacks and cereals to supplement bioactive compounds beneficial to human health.

Sequestration of Copper from β-Amyloid Promotes Selective Lysis by Cyclen-Hybrid Cleavage Agents

Decelerated degradation of beta-amyloid (Abeta) and its interaction with synaptic copper may be pathogenic in Alzheimer disease. Recently, Co(III)-cyclen tagged to an aromatic recognition motif was shown to degrade Abeta in vitro. Here, we report that apocyclen attached to selective Abeta recognition motifs (KLVFF or curcumin) can capture copper bound to Abeta and use the Cu(II) in place of Co(III) to become proteolytically active. The resultant complexes interfere with Abeta aggregation, degrade Abeta into fragments, preventing H2O2 formation and toxicity in neuronal cell culture. Because Abeta binds Cu in amyloid plaques, apocyclen-tagged targeting molecules may be a promising approach to the selective degradation of Abeta in Alzheimer disease. The principle of copper capture could generalize to other amyloidoses where copper is implicated.

Protocol for Automated Kinetic Investigation/Optimization of the RAFT Polymerization of Various Monomers

AbstractA standard protocol for the parallel optimization of Reversible Addition–Fragmentation Chain Transfer (RAFT) polymerization conditions using an automated synthesizer is described in this report. Experimental design based on the knowledge obtained from previous screening experiments and the literature is the most effective initial step of the High‐Throughput Experimentation (HTE) cycle. In this paper, the polymerization procedure is explained step‐by‐step including preparation of stock solutions, inertization of the reactors and synthesizer environment, liquid transfers to or from the reactor vessels including sampling, as well as termination of the polymerization. Automated characterization techniques for the determination of monomer conversion and the molecular weight distribution of the polymers are discussed to complete the HTE cycle. Consequently, analysis of the data obtained from parallel screening of reactions and their products will result in the design of the next experimental cycle.

EUCAST Definitive Document EDef 7.1: method for the determination of broth dilution MICs of antifungal agents for fermentative yeasts: Subcommittee on Antifungal Susceptibility Testing (AFST) of the ESCMID European Committee for Antimicrobial Susceptibility Testing (EUCAST)∗

INTRODUCTIONAntifungal susceptibility tests are performed onfungi that cause disease, especially if they belongto a species exhibiting resistance to commonlyused antifungal agents. Antifungal susceptibilitytesting is also important for resistance surveil-lance, for epidemiological studies and forcomparing the in-vitro activity of new and exist-ing agents.Dilution methods are used to establish theMICs of antimicrobial agents. These are thereference methods for antimicrobial susceptibilitytesting, and are used mainly to establish theactivity of a new antifungal agent, to confirm thesusceptibility of organisms that give equivocalresults in routine tests, and to determine thesusceptibility of fungi where routine dilution testsmay be unreliable. Fungi are tested for theirability to produce visible growth in microdilutionplate wells containing broth culture media andserial dilutions of the antifungal agents (brothmicrodilution). The MIC is defined as the lowestconcentration (in mg⁄L) of an antifungal agentthat inhibits the growth of a fungus. The MICprovides information concerning the susceptibil-ity or resistance of an organism to the antifungalagent and can help in making correct treatmentdecisions.The method described in this document isintended for testing the susceptibility ofyeasts that cause clinically significant infections(primarily Candida spp.). The method encom-passes only those yeasts that are able to fermentglucose. Thus, the susceptibility of non-fermenta-tive yeasts, e.g., Cryptococcus neoformans, cannotbe determined by the current procedure, and themethod is not suitable for testing the yeast formsof dimorphic fungi.SCOPEThe standard method described in this documentprovides a valid method for testing the suscepti-bility of glucose-fermenting yeasts to antifungalagents by determination of the MIC. MICs indi-cate the activity of a given antifungal drug underthe described test conditions, and can be used inmaking decisions concerning patient manage-ment after taking into account other factors, e.g.,pharmacokinetics, pharmacodynamics and resis-tance mechanisms. The MIC also allows fungi tobe categorised as ‘susceptible’ (S), ‘intermediate’(I) or ‘resistant’ (R) to a drug. In addition, MICdistributions can be used to define wild-type ornon-wild-type fungal populations.This method is intended primarily to facilitatean acceptable degree of conformity, i.e., agree-ment within specified ranges among laboratories,in measuring the susceptibility of yeasts to anti-fungal agents. The method is designed to be easyto perform, rapid, economical, and suitable forreading by microdilution plate readers in order toallow direct transfer, storage and manipulation ofthe data by computer. The method is alsointended to yield results that are concordantwith those obtained using the procedure

Stock solution preparation processes in ferrite manufacture by cryochemical technology

It is shown that for synthesis of nickel-zinc ferrite materials aqueous solutions of nickel, zinc, and iron (II) sulfates are required. These sulfates form true solution in any ratio of the components at 1.5–2.5 pH. This fact is substantiated making use of solubility curves. The kinetics of dissolution of single-component substances has been studied. The peculiarities of the methods of mixing of ferrite-forming salts are noted and the accuracy of each method has been assessed.

Determination of the Substrate Specificity of Tripeptidyl-peptidase I Using Combinatorial Peptide Libraries and Development of Improved Fluorogenic Substrates

Classical late-infantile neuronal ceroid lipofuscinosis is a fatal neurodegenerative disease caused by mutations in CLN2, the gene encoding the lysosomal protease tripeptidyl-peptidase I (TPP I). The natural substrates for TPP I and the pathophysiological processes associated with lysosomal storage and disease progression are not well understood. Detailed characterization of TPP I substrate specificity should provide insights into these issues and also aid in the development of improved clinical and biochemical assays. To this end, we constructed fluorogenic and standard combinatorial peptide libraries and analyzed them using fluorescence and mass spectrometry-based activity assays. The fluorogenic group 7-amino-4-carbamoylmethylcoumarin was incorporated into a series of 7-amino-4-carbamoylmethylcoumarin tripeptide libraries using a design strategy that allowed systematic evaluation of the P1, P2, and P3 positions. TPP I digestion of these substrates liberates the fluorescence group and results in a large increase in fluorescence that can be used to calculate kinetic parameters and to derive the substrate specificity constant kcat/KM. In addition, we implemented a mass spectrometry-based assay to measure the hydrolysis of individual peptides in peptide pools and thus expand the scope of the analysis. Nonfluorogenic tetrapeptide and pentapeptide libraries were synthesized and analyzed to evaluate P1' and P2' residues. Together, this analysis allowed us to predict the relative specificity of TPP I toward a wide range of potential biological substrates. In addition, we evaluated a variety of new fluorogenic peptides with a P3 Arg residue, and we demonstrated their superiority compared with the widely used substrate Ala-Ala-Phe-AMC for selectively measuring TPP I activity in biological specimens.

Autoantibodies to Redox-modified Oligomeric Aβ Are Attenuated in the Plasma of Alzheimer's Disease Patients

Accumulation of Abeta protein in beta-amyloid deposits is a hallmark event in Alzheimer's disease (AD). Recent findings suggest anti-Abeta autoantibodies may have a role in AD pathology. However, a consensus has yet to emerge as to whether endogenous anti-Abeta autoantibodies are elevated, depressed, or unchanged in AD patients. Whereas experiments to date have used synthetic unmodified monomeric Abeta (Abetamon) to test autoimmunity, up to 40% of the Abeta pool inB AD brain consists of low molecular weight oligomeric cross-linked beta-amyloid protein species (CAPS). Recent studies also suggest that CAPS may be the primary neurotoxic agent in AD. In the present study, AD and nondemented control plasma were analyzed for immunoreactivity to CAPS and Abetamon. Plasma of both nondemented and AD patients were found to contain autoantibodies specific for soluble CAPS. Nondemented control and AD plasmas demonstrated similar immunoreactivity to Abetamon. In contrast, anti-CAPS antibodies in AD plasma were found to be significantly reduced compared with nondemented controls (p=0.018). Furthermore, age at onset for AD correlated significantly (p=0.041) with plasma immunoreactivity to CAPS. These data suggest that autoantibodies to CAPS are depleted in AD patients and raise the prospect that immunization with anti-CAPS antibodies might provide therapeutic benefit for AD.

Preparation of stock solutions of macrolide and ketolide compounds for antimicrobial susceptibility tests.

Stock solutions of telithromycin, ABT-773, azithromycin, clarithromycin, erythromycin, roxithromycin and dirithromycin were each prepared with eight different combinations of solvents and diluents. Broth microdilution trays were then prepared and frozen at -60 degrees C. Standard quality control strains were evaluated periodically during a 12-week storage time. There were no significant changes in MICs with different solvents and diluents. It was concluded that the easiest approach was to dissolve each compound in water with a small volume (< 2.5 microL/mL) of glacial acetic acid added in a dropwise fashion, followed by further dilutions in deionised water.

Gas Chromatography–Mass Spectrometry Analysis of Organic Acids: Altered Quantitative Response for Aqueous Calibrators and Dilute Urine Specimens

Urinary organic acid analysis is a key analytical procedure for laboratories involved in the diagnosis of inherited metabolic disorders (1). Gas chromatography–mass spectrometry (GC-MS) is by far the most widely used method, and it is generally performed after oxime-trimethylsilyl derivatization of an ethyl acetate extract. A previous report briefly pointed out an erratic analytical phenomenon we observed with this method for some acids extracted from physiologically diluted urine specimens (with a low creatinine content) or from aqueous solutions (2). This so-called “dilution effect” has also been observed in other laboratories (e.g., by N. Chamoles, Fundation para el Estudio de las Enfermedades Neurometabolicas, Buenos Aires, Argentina). The analytical method we used for profiling urinary organic acids has been described in detail (2), including the sources of chemicals, the preparation of stock solutions, the ethyl acetate extraction, the oxime-trimethylsilyl derivatization, and the GC-MS operating conditions. Briefly, the extraction and derivatization procedures are as follows: Urine or aqueous solutions (1.5 mL) with internal standards tropate and 2-ketocaproate added are treated with hydroxylamine hydrochloride (30 min at 60 °C), acidified to pH 1 with HCl, saturated with NaCl, and extracted three times with 6 mL of ethyl acetate. The three successive organic phases, each supplemented with 100 μL of a 1 mol/L ammonia solution in ethanol, are evaporated to dryness in the same tube, under nitrogen at 50 °C. The residue is taken up in ethanol, re-evaporated to dryness, and silanized with a mixture N , O -bis(trimethylsilyl)trifluoroacetamide–trimethylchlorosilane–pyridine (99:1:20, by volume) in a stoppered tube for 30 min, 60 °C. GC-MS is operated as described under electron-impact fragmentation and with the scan mode in data acquisition. Quantitative results obtained for control urines and aqueous solutions allowed us to compare the recoveries of acids extracted from water instead of urine. Control urines were prepared by …

Low temperature formation of sol-gel derived ferroelectric lead zirconate titanate (Pb(ZrxTi1-x)O3, x = 0.3) thin films

Crack-free transparent thin films of ferroelectric Pb(Zr 0.3 ,Ti 0.7 )O 3 (PZT) with the perovskite structure were prepared by spin-coating a solution of complex alkoxides, followed by drying and then firing at the temperatures less than 500°C. The preparation of stock solution, erring, and firing of films are described. The coatings with selective orientations have been prepared by using selective processing parameters. The influence of low-temperature processing steps on texture development will be reported. The formation and growth of polymeric particles in the hydrolysis and condensation of PZT sol-gel precursor solutions have been investigated by using photon correlation spectroscopy (PCS). small angle x-ray scattering (SAXS) and by measuring their rheological properties. It has been possible to follow the growth of the particles in the sol by the different techniques used from initial values of <4nm up to ca 100nm. It has been shown that the particles are rods rather than spheres. The effects of particle shape and solution chemistry on the crystal phase formation and texture development will be discussed.

Preparation and electrical properties of Ba0.6Sr0.4TiO3 thin films deposited by the sol-gel method

Barium strontium titanate Ba0.6Sr0.4TiO3 thin film capacitors with metal oxide La0.5Sr0.5CoO3 electrodes fabricated by sol-gel processing have been studied. The preparation of stock solution, firing and annealing of the films are described. Structural, compositional and morphological analyses using x-ray diffraction and SEM/EDS are reported. The film properties are between those of crystalline cubic perovskite and amorphous films. At room temperature the dielectric constant and loss factor of films at 20kHz were 40 and 0.038 respectively. The films showed a Debye-type dielectric relaxation with increasing temperature. The leakage current density is about 1.1 μA/cm2 at 0.10 MV/cm.

Preparation of Pb(Zr,Ti)O3 thin films by sol gel processing: Electrical, optical, and electro-optic properties

Crack-free transparent ferroelectric polycrystalline Pb(Zr,Ti)O3 thin films were prepared by spin-coating solutions of complex alkoxides. The preparation of stock solution, firing, and annealing of films was described. The coating of the intermediate layer of Al2O3 increased the adhesion between Pb(Zr,Ti)O3 thin films and glass substrates. The crystalline phases of films with varying Zr/Ti ratios were investigated. The dielectric constants were about 260. The remanent polarization and coercive field were 6.6 μC/cm2 and 26.7 kV/cm, respectively. The refractive index of the perovskite Pb(Zr,Ti)O3 films was 2.6 at 6328 Å, and the absorption edge was at 3400 Å. The quadratic and linear electro-optic effects were measured with respect to the Zr/Ti ratio from 40/60 to 60/40 for films grown on glass substrates. The quadratic and linear electro-optic coefficients were about 1×10−18 m2 /V2 and 2.4×10−11 m/V at 6328 Å, respectively.

Certification Corner

This month's “Certification Corner” covers hypochlorite stock solution preparation, chlorine solution calculations, molecular weight of hydrated lime, causes of permanent water hardness, and volume calculations for cylindrical tanks, elevated storage tanks, and water mains.

Electron microscopic appearances and implications of neuropeptide fibrillary forms

The appearance of over 20 neuropeptides or peptide fragments, prepared at mM concentrations in saline solutions, has been investigated under the electron microscope. Numerous linear unbranched fibrils, generally ranging in diameter from 50Å to 90Å, were readily identified in preparations of cholecystokinin octapeptide, caerulein, gastrin related penta- and tetrapeptides, eledoisin, substance P, several substance P carboxyterminal fragments, somatostatin (open ring form) and bombesin. Several implications of these findings are discussed including the possible relevance of these polymeric peptide structures to peptide conformation in vivo and to practical procedures such as the preparation of stock solutions and tissue extraction.

Tissue Culture Propagation of African Violets1

Abstract Over 70,000 plants of African violet (Saintpaulia ionantha Wendl.) from over 20 cultivars have been produced by tissue culture in this laboratory. All cultures were started from a single mother stock plant of each cultivar. The ease of the method is enhanced by using premixed inorganic salts which eliminate preparation of stock solutions and the development of media for shoot production and root production that differ only in growth regulators. The plant and flowers appear true-to-type and variegations were not lost or distorted. The plants had the typical flat leafed morphology; none had the unusual upright morphology encountered in some cases by Start and Cumming (1). Only 2 plants had obvious differences in phenotype. These were albinos from ‘Mary D’ and could not survive outside artificial media.

Chapter 9 Growth of Functional Glial Cells in a Serumless Medium

Publisher Summary This chapter discusses the growth of functional glial cells in a serumless medium. The medium that is chosen for use in these studies is generally richer in synthetic nutrients than are other available media and because of the possibility that certain nutrients, reducing agents, trace metal salts, and folinic acid present in this medium, but not in others, would be significant factors in the ability of cells to grow without serum. The chapter discusses the ingredients of the medium, the amounts that are used in the preparation of stock solutions and the final concentrations of each ingredient; and describes the procedure that is employed in preparing the medium. It is generally advisable to add the calcium and magnesium salts last to avoid possible precipitation of some of the salts. Most of the stock solutions could be stored frozen for long periods of time (more than 1 year), and some are best stored at 4°C to avoid precipitation of the ingredients. The medium itself, once prepared, could be stored at 4°C for at least 2-3 months, and probably for periods of time up to 6 months. Without added serum, if the medium is frozen, some precipitation of salts and insoluble amino acids would occur.