Phosphate Buffer Suspensions Research Articles

Characterization of porous starch from edible canna (Canna edulis Kerr.) produced by enzymatic hydrolysis using thermostable α-amylase

Porous starches are essential modified starches that have potential application as natural absorbents and contain abundant micro sized pores. Increasing interest is directed to utilizing the properties of porous starches in various starchy foods, such as Canna edulis Kerr. To date, no report about edible canna porous starch is available. Therefore, this study aimed to characterize the porous starch from edible canna produced by enzymatic hydrolysis using thermostable α-amylase. A starch suspension (25%, w/v) in phosphate buffer (0.1 M, pH 6.5) was added the thermostable α-amylase (100 U/g, 200 U/g and 300 U/g) and then incubated at 60 °C and 80 rpm for 8 h. The pellets were dried at 40 °C for 48 h. The SEM results displayed that the increase in enzyme concentration caused the formation of larger pores on the starch granule surface due to amylose degradation. FTIR and XRD analysis showed that enzymatic hydrolysis did not affect the crystalline structure of the edible canna porous starch. Furthermore, the edible canna porous starch exhibited high solubility and oil and water absorption capacity. Thus, the porous starch from C. edulis Kerr. could be used as a probiotic, flavoring, or drug delivery agent by microencapsulation.

Repeat-Dose Toxicity Study of a Lyophilized Recombinant Protective Antigen-Based Anthrax Vaccine Adjuvanted With CpG 7909.

A recombinant protective antigen (rPA) anthrax vaccine candidate (rPA7909) was developed as a next-generation vaccine indicated for postexposure prophylaxis of disease resulting from suspected or confirmed Bacillus anthracis exposure. The lyophilized form of rPA7909-vaccinated candidate contains 75 µg purified rPA, 750 µg aluminum (as Alhydrogel adjuvant), and 250 µg of an immunostimulatory Toll-like receptor 9 agonist oligodeoxynucleotide CpG 7909 in a 0.5 mL phosphate-buffered suspension. General toxicity and local reactogenicity were evaluated in Sprague Dawley rats vaccinated with the full human dose of rPA7909 by intramuscular injection. Animals were immunized on study days 1, 15, and 29. Control groups were administered diluent only or adjuvant control (excipients, CpG 7909, and Alhydrogel adjuvant in diluent) intramuscularly at the same dose volume and according to the same schedule used for rPA7909. Toxicity was assessed based on the results of clinical observations, physical examinations, body weights, injection site reactogenicity, ophthalmology, clinical pathology (hematology, coagulation, and serum chemistry), organ weights, and macroscopic and microscopic pathology evaluation. The immune response to rPA7909 vaccination was confirmed by measuring serum anti-PA immunoglobulin G levels. The rPA7909 vaccine produced no apparent systemic toxicity and only transient reactogenicity at the injection site. The injection site reaction from animals receiving the adjuvant control was very similar to those receiving rPA7909 with respect to the inflammation. The inflammatory response observed in the injection site and the draining lymph nodes was consistent with expected immune stimulation. The overall results indicated a favorable safety profile for rPA7909.

Phenoloxidase activity and haemolymph cytology in honeybees challenged with a virus suspension (deformed wings virus DWV) or phosphate buffered suspension (PBS)

ABSTRACT: The innate immune system of honeybees mainly consists in antimicrobial peptides, cellular immunity and melanisation. In order to investigate the immune response of honeybees to immune stressors, three stress degrees were tested. Newly emerged bees naturally DWV-infected were collected from a Varroa mite-free apiary and divided into three experimental groups: naturally DWV infected bees, PBS injected bees, and artificially DWV super infected bees. Phenoloxidase activity and haemolymph cellular subtype count were investigated. Phenoloxidase activity was highest (P<0.05) in DWV-superinfected bees, and the haemocyte population differed within the three observed groups. Although, immune responses following DWV infection have still not been completely clarified, this investigation sheds light on the relation between cell immunity and the phenoloxidase activity of DWV-naturally infected honeybees exposed to additional stress such as injury and viral superinfection.

Quantifying the Responses of Three Bacillus cereus Strains in Isothermal Conditions and During Spray Drying of Different Carrier Agents.

Spray drying is a widely used method for producing milk powder. This process is not aimed to cause microbial inactivation, thus sporeforming bacteria may be abundant in the microbiota of milk powder. The first aim of this study was to determine the inactivation kinetics parameters in capillary tubes of three Bacillus cereus strains (436, B63, 540) in three menstrua (whole milk, phosphate buffer, and talc suspension) at 90, 100, and 110°C. D-values for B. cereus in the three menstrua were not significantly different at the highest tested temperature (p > 0.05). Thus, talc was chosen as a carrier agent to allow the recovery of B. cereus from spray dried materials given its low interference on inactivation kinetics. B. cereus spores were also inoculated in whole milk and skim milk following spray drying at 95, 105, and 110°C (outlet temperature). After the spray drying runs, B. cereus spores were counted and the number of decimal reductions (γ) calculated. A correlation between the small diameter of the particles with the survival of spores of three B. cereus strains was found, and B. cereus 436 presented consistently the lowest γ no matter temperature and a carrier agent. The highest γ was found when talc powder was used, which suggest that this carrier agent does not protect B. cereus spores during spray drying. Spray drying of milk can lead to up to 4 γ (strain 540) of B. cereus spores but depending on the strain less than one γ (strain 436) could be observed. This study contributes to the knowledge on the microbiology of low water activity foods by providing novel findings regarding the fate of three B. cereus strains to different spray drying conditions. Acknowledging the variability of inactivation of B. cereus during spray drying is key in the current context of food safety in which the quantification of effects of unit operations must be known for the validation of processes and development of more robust formulations.

Preparation and evaluation of wet-milled usnic acid nanocrystal suspension for better bioaffinity

Objective: To prepare a new nanosystem of usnic acid (UA) with higher solid content and higher bioavailability.Methods: Usnic acid nanocrystal suspensions were prepared by the wet milling method, and then the particle size distributions and zeta potential were determined with the Nano ZS90 laser diffraction particle size analyzer. The particles morphology of UA-NCS were observed by scanning electron microscopy method. In addition, solubility and dissolution of UA-NCS in water and phosphate buffer solution were determined in vitro, analyzed by the HPLC method, and then the cellular uptake and pharmacokinetic were carried out on the Caco-2 cells and rats, analyzed by the UPLC-MS/MS method.Results: Particle size distributions and zeta potential of the UA nanocrystal suspension were 268.7 ± 4.0 nm and –23.1 ± 0.7 mV, respectively. About the dissolution rate of UA, nanosuspension were significantly faster and higher than common suspension in water and phosphate buffer. And in cellular uptake experiments, the ratio of the maximum amount of drug in unit protein of UA nanosuspension to common suspension was 2.8 times. In rats, oral absorption of nanocrystal UA were superior to the ordinary groups, with the 348% of the maximum concentration and 181% of the AUC after the same dosage administration.Conclusion: The wet-milling technique was suitable for the preparation of UA nanocrystal suspension, and a new nanosystem of UA with higher solid content and higher bioavailability was achieved.

Highly Sensitive Glucose Biosensor Based on One-Pot Biochemical Preoxidation and Electropolymerization of 2,5-Dimercapto-1,3,4-thiadiazole in Glucose Oxidase-Containing Aqueous Suspension

A novel and high-performance biosensing platform was prepared on the basis of one-pot biochemical preoxidation and electropolymerization of monomer (BPEM) for high-load and high-activity immobilization of enzymes. As representative materials here, 2,5-dimercapto-1,3,4-thiadiazole (DMcT) was used as the monomer, glucose oxidase (GOx) was used as the model enzyme, and enzymatically generated H2O2 (EG-H2O2) in the presence of glucose was used as the preoxidant. In the BPEM protocol, glucose was added to a pH 7.0 phosphate buffer suspension containing ultrasonically dispersed DMcT and GOx, in order to enzymatically generate H2O2, which preoxidized DMcT to DMcT oligomers/polymer (DMcTO) and thus led to the formation of DMcTO-GOx composites with a great deal of GOx entrapped; the composites were then co-electrodeposited with poly(DMcT) on a Au electrode. For comparison, the enzyme immobilization was also conducted by a preoxidation-free conventional electropolymerization protocol (CEP), as well as a chemical preoxidation and electropolymerization of monomer (CPEM) protocol with externally added H2O2 (EA-H2O2) as the preoxidant. The glucose biosensors constructed by the BPEM and CPEM protocols exhibited detection sensitivities enhanced by 119 and 88 times, respectively, compared to that constructed by the CEP protocol, as well as limits of detection lowered by ca. 2 orders of magnitude. The higher sensitivity of the enzyme electrode prepared by the BPEM protocol compared to that prepared by the CPEM protocol is probably due to the improved proximity of biochemical preoxidation around the enzyme molecules and thus a larger enzyme load. The electrochemical quartz crystal microbalance technique was used to investigate various electrode modification processes, which also revealed that poly(DMcT) could be cathodically detached from the electrode surface, favorably enabling the electrochemical regeneration of the electrode substrate. The proposed BPEM strategy is recommended for wide biosensing and biocatalysis applications based on many other polymers/enzymes.

Concanavalin A Binding on PHEMA Beads and Their Interactions with Myeloma Cells

The aim of this study is to prepare concanavalin A (Con A) bound poly(2-hydroxy ethyl methacrylate) (PHEMA) beads for cell affinity chromatography. In the first step, PHEMA beads were produced by suspension polymerization, and activated by cyanogen bromide (CNBr) in an alkaline medium (pH 11.5), and then, the bio-ligand “Con A” was attached by covalent binding onto the CNBr activated beads. PHEMA beads were characterized by scanning electron microscopy (SEM), surface area and pore size measurements. The PHEMA beads have a spherical shape and porous structure. The specific surface area of the PHEMA beads was found to be 39.7 m2/g with a size range of 150–200 μm in diameter and the swelling ratio was 55%. The amount of bound Con A was controlled by changing pH and the initial concentrations of CNBr and Con A. The non-specific adsorption of Con A on the plain PHEMA beads was 0.1 mg/g. The maximum Con A binding was 4.8 mg/g at pH 7.25. Both plain and Con A bound PHEMA beads were interacted first with the myeloma cell suspension in phosphate buffer. Myeloma cell attachment was very low for the plain PHEMA beads, while the number of myeloma cells attached increased almost 20 fold when the Con A bound beads were used. In order to look at whether or not the interaction of the Con A bound PHEMA beads and myeloma cells are affected from the biological molecules and other cells in the medium. We selected sheep blood itself as the medium, and mixed with the myeloma cell suspension and changed the environment. Cell adhesion decreased but not very significantly by changing the medium from simple buffer to sheep blood.

Kinetic of production and mode of action of the Lactobacillus paracasei subsp. paracasei anti-listerial bacteriocin, an Algerian isolate

Lactobacillus paracasei subsp. paracasei was isolated in our laboratory from breast-fed newborn faeces and identified phenotypically and genotypically. The strain was able to produce a bacteriocin-like substance active towards listerial strains ( Listeria innocua CLIP 74915 and Listeria monocytogenes EGDe). The maximum production of the substance by producing strain was detected in the late logarithmic growth phase (14 h in MRS and 18 h in BHI broths). It displayed bactericidal mode of action with leakage of cellular content (K + and ATP) leading to cell lysis as secondary effect. A reduction of about 5 log with 35.7 ± 0.2% of cell lysis and of about 4 log with 82.0 ± 0.3% of cell lysis were observed, respectively, in a phosphate buffer and BHI suspensions. This was further demonstrated by electron microscopy that showed severe modifications in the cell morphology with a concomitant lysis.

A study of steroid hydroxylation activity of Curvularia lunata mycelium

It has been demonstrated that the mycelium of Curvularia lunata at the end of the logarithmic growth phase displays a maximal 11-hydroxylase activity towards cortexolone (4-6 g/l) used for transformation as a microcrystalline suspension in phosphate buffer. The mycelium at a later stage of fungal growth displays an elevated 14-hydroxylase activity, necessary for generation of 14-hydroxyandrostenedione. The effects of different forms of substrate added to the reaction mixture, age and concentration of mycelium, and fungal clones tolerant to salts of heavy metals (0.35-0.5%) were studied to remove the side 14-hydroxylation, accompanying the main cortexolone transformation. Mycelia of the fungal clones tolerant to Co2+ and Cu2+ displayed a weak hydroxylase activity or its complete absence and an elevated content of melanin, the biosynthesis of which is intensified under adverse conditions. The results obtained suggest that the transformation of steroids by the studied C. lunata strain is a detoxication of foreign compounds.

Luminescent Silole Nanoparticles as Chemoselective Sensors for Cr(VI)

Colloidal suspensions of 3-aminopropylmethyl(tetraphenyl)silole nanoparticles can be used as selective chemosensors for carcinogenic chromium(VI) analyte. Methylhydrosilole is functionalized by hydrosilation of allylamine, and the colloid is prepared by the rapid addition of water to a THF solution of the silole. The method of detection is through electron-transfer quenching of the fluorescence of the silole colloid (lambda(em) = 485 nm at 360 nm excitation) by the analytes, with hundred parts per billion detection limits. Stern-Volmer plots are linear up to 10 ppm in the case of chromium, but exhibit saturation behavior near 5-10 ppm for arsenic. Dynamic light scattering experiments and AFM measurements show the particle sizes to be around 100 nm in diameter and dependent on solvent composition, with a particle size dispersity of +/-25%. The fluorescence lifetimes of the silole in solution and colloid are approximately 31 ps and approximately 4.3 ns, respectively, while the silole has a lifetime of 6 ns in the bulk solid. A minimum volume fraction of 80% water is necessary to precipitate the colloid from THF, and the luminescence continues to rise with higher water fractions. Colloids in a pH 7 phosphate-buffered suspension show both higher sensitivity and greater selectivity (100-fold) for CrO4(2-) detection than for other oxoanion interferents, NO3-, NO2-, SO4(2-), and ClO4-.

A piezoelectric immunosensor based on antibody entrapment within a non-totally rigid polymeric film

A piezoelectric immunosensor is described which consists of a gold filmed quartz crystal, whose surface is modified with a thin Nafion layer entrapping known amounts of the specific antibody. This layer was applied by droplet evaporation on the gold surface of a mixture prepared by mixing a stock ethanol solution of Nafion with a stock antibody suspension in aqueous phosphate buffer. The coatings thus obtained could be easily and quickly removed by simple soaking in ethanol in an ultrasonic bath and renewed by repeating the procedure above, which resulted in quite reproducible coatings. The sensor was optimised with regard to parameters involved in its preparation and the assay process, in order to minimize viscosity-induced effects and energy-dissipation processes caused by the viscoelastic properties displayed by the proteic–polymeric layer adopted, so that frequency decreases found can reflect primarily mass changes at the surface. It permitted a reliable determination of enterotoxin in a wide range (up to about 800 ng ml −1), but a linear dependence was shown only at low concentrations (up to about 100 ng ml −1). The responses were characterized by good reproducibility and a DL of about 0.6 ng ml −1 could be estimated for a signal-to-noise ratio of 3. The profitable permeation properties of Nafion made these responses scarcely affected by the presence in the analyzed samples of high amounts of proteins, thus suggesting the possibility of using well simplified procedures for the preparation of biological samples.

The Effect of Phosphate Buffer on Aerosol Size Distribution of Nebulized Bacillus subtilis and Pseudomonas fluorescens Bacteria

During bioaerosol research microorganisms are frequently aerosolized from phosphate-buffered suspension via air-jet nebulization. Buffer will therefore be present in organism-free droplets (''empties) as solutes in hydrous surface coatings of airborne organisms or as dry surface coatings on organisms. It might be expected that the buffer would influence the resulting aerosol size distribution and that the influence might vary with relative humidity. In this work we examined the effect of various buffer concentrations on the aerosol size distribution of Bacillus subtilis (B. subtilis) and Pseudomonas fluorescens ( P. fluorescens ) at various relative humidities. Microorganism suspensions in distilled deionized water and phosphate-buffered water were prepared and nebulized from a 3-jet Collison nebulizer into a sampling chamber maintained at 10% relative humidity. The aerosol was then conducted to a second chamber to which moist air was added to achieve the target relative humidity. Particle aerodynamic si...

食肉中での大腸菌Ｏ１５７：Ｈ７の放射線殺菌効果

Escherichia coli O157: H7 is a rapidly emerging food-born pathogen which has been linked to outbreaks of hemorrhagic diarrhea in Japan, USA or many European countries. From this study, two strains of E. coli O157: H7 were isolated from beef and chicken meats in each one sample of 4 replicates. Some of the biochemical characteristics of these isolates were different from type strain IID959. These isolates could grow quickly at 10°C on cultivation of nutrient agar. D10 value of these isolates were obtained to be 0.06kGy in 0.067M phosphate buffer suspension which were highly sensitive than D10 value of 0.12kGy on type strain IID959. On the irradiation effect of type strain IID959 in ground beef, D10 value was obtained as 0.26kGy at fresh condition and 0.46kGy at frozen condition, respectively. From these results, necessary dose for elimination of E.coli O157: H7 was decided as 1.5kGy for fresh meats and 3kGy for frozen meats.

EVALUATION OF A RIBOFLAVIN‐METHIONINE MIXTURE TO IMPROVE THE QUALITY OF AQUACULTURED CATFISH FILETS DURING THE CHILLING PROCESS

ABSTRACTAn optimized riboflavin‐methionine (RM) mixture with Escherichia coli (target organism) was evaluated for improving the quality of catfish filets during the chilling process. The RM mixture (pH 7.2) containing riboflavin (10μM), methionine (20 mM) and EDTA (1 mM) was photoactivated. E. coli cells grew in a medium containing l‐methionine when exposed to fluorescent light and grew in a RM mixture in the dark. However, the activated RM mixture injured and killed E. coli cells. As the concentration of riboflavin increased, the number of survivors decreased. The concentration of methionine did not significantly decrease the survival rate of E. coli. As pH increased, the number of killed and injured E. coli cells increased. The RM mixture injured and/or killed a low load of E. coli cells faster than a high load. Methionine solution or RM mixture added to the suspension in phosphate buffer (15 mM, pH 7.2) and photoactivated at 0 and 24C for 8h to simulate the chilling water significantly reduced the total coliform counts but not the standard plate counts. However, when the catfish filets were suspended in a RM mixture at 0 and 24C for 2h to simulate the chilling process, there was no reduction in standard plate or total coliform counts.

Ultrasound-enhanced hydroxyl radical production from two clinically employed anti-cancer drugs, adriamycin and mitomycin C

Continuous-wave 1 MHz ultrasound at the therapeutic intensity of 1 W cm −2 was found to enhance significantly the hydroxyl radical production from two clinically employed redox cycling drugs, viz. adriamycin (doxorubicin) and mitomycin C, with respect to the control drug-free insonicated phosphate buffer suspension. Benzoic acid (Bz) was employed as a sensitive chemical probe to detect hydroxyl radicals (HO ■). Bz is initially non-fluorescent and upon aromatic hydroxylation becomes permanently fluorescent. A series of time course studies up to 30 min were performed on drug suspensions to characterize the HO ■ generation in the presence and absence of ultrasound at 37°C. Identical ultrasound treatments on non-redox cycling clinical drugs, 5-fluorouracil and methotrexate, did not yield any significant enhancement in the production of HO ■ in comparison to the drug-free insonicated phosphate buffer suspension. Ultrasound exposures of 30 min did not yield measurable changes in the chemical constitution of the four drugs as assessed through high-performance liquid chromatography. Identical ultrasound treatments at 3 MHz did not produce any HO ■ in the presence or absence of these four anti-cancer drugs. Free radical scavengers such as mannitol, superoxide dismutase, catalase and a transition metal chelating agent were employed independently to elucidate the chemical species and pathways involved in the production of the HO ■. The findings strongly implicate an active role of acoustically induced cavitation in potentiating redox cycling drugs via chemical reduction and, thereafter, production of the OH ■ via Fenton's pathway.

Molecular mechanism of drug photosensitization Part 6. Photohaemolysis sensitized by tolmetin

The photosensitizing properties of tolmetin, 5-( p-toluoyl)-1-methyl-2-pyrrolyacetic acid (TLM), have been studied in vitro following the lysis of erythrocytes in phosphate buffer suspensions irradiated with UVA light in the presence of the drug. It was found that the phototoxic properties of the drug are negligible in nitrogen and significant in aerated medium, but that they decrease in oxygen-saturated solution. The investigation of the drug photolysis showed that TLM undergoes photodecarboxylation to p-tolyl 1,2-dimethyl-5-pyrrolyl ketone in nitrogen and to p-tolyl 1-methyl-2-hydroxymethyl-5-pyrrolyl ketone and 5-( p-toluoyl)-1-methyl-2-pyrrole carbaldehyde in air. These photoproducts also undergo photodegradation. The comparison between the photohaemolysis and photolysis results and the effect of suitable additives such as sodium azide, mannitol, butylated hydroxy-anisole, reduced glutathione, superoxide dismutase and copper(II) suggest that the phototoxicity of TLM can be attributed essentially to singlet oxygen in the first step and to its photoproducts when they accumulate and compete with the starting drug in light absorption. Their phototoxic effect is much higher with respect to that of TLM, as shown by comparison of the doses needed to attain 50% photohaemolysis.

Antioxidant effect of inorganic ions on UVC and UVB induced lipid peroxidation

Phosphate buffer suspensions of unilamellar liposomes of phosphatidylcholine were irradiated with UVC (254 nm) and UVB (300 nm) light. The irradiation provoked lipid peroxidation and liposome lysis with release of entrapped glucose-6-phosphate. At the same intensity of absorbed light, the photochemical effect at 254 nm is higher than at 300 nm. The addition of copper(II) and manganese(II) reduced both the peroxidation and the lysis. The copper showed an inhibitory effect only on the process provoked by the 254 nm irradiation, whereas the manganese was efficient both at 254 and 300 nm. The results are interpreted with a mechanism of peroxidation and quenching, involving photoformation of peroxyl radicals that are scavenged by manganese(II) and copper(I), with consequent breaking of the radical chain and reduction of the peroxidation rate. The copper(I), which is the active species, can be formed only at 254 nm by electron capture. The experimental data fit the kinetic equations obtained by the proposed mechanism by means of computer software.

The utilization of thiocyanate as a nitrogen source by a heterotrophic bacterium: the degradative pathway involves formation of ammonia and tetrathionate

A Gram-negative soil bacterium (isolate 26B) has been shown to utilize up to 100 mM thiocyanate as a source of nitrogen when supplied with glucose as the source of carbon and energy. During growth of isolate 26B with thiocyanate as the source of nitrogen, no ammonia, nitrate, nitrite, cyanide, cyanate, sulfate, sulfite, sulfide or carbonyl sulfide was detected in the growth medium. Growth of the bacterium on 14C-labelled thiocyanate (1.6 microCi) and glucose, yielded 14C-labelled carbon dioxide (0.9 microCi). The addition of 2.9 mM thiocyanate to a bacterial suspension in phosphate buffer (50 mM, pH 7.4) resulted in the utilization of 2.1 mM thiocyanate and the production of 2.0 mM ammonia. This activity was inducible and only occurred after growth of the bacterium with thiocyanate as the source of nitrogen. Tetrathionate (0.7 mM) was detected in the medium after the utilization of thiocyanate (2.4 mM) by a suspension of the bacterium in phosphate buffer, and thiosulfate (1.0 mM) was detected as an intermediate. The addition of sulfide or thiosulfate to the bacterial suspension also resulted in the formation of tetrathionate. The utilization of both of these compounds appeared to be constitutive. A pathway for thiocyanate utilization by isolate 26B is proposed which involves the hydrolysis of thiocyanate to produce cyanate and sulfide. The cyanate then undergoes further hydrolysis to form ammonia and carbon dioxide. The sulfide is ultimately oxidized to tetrathionate via a pathway which includes thiosulfate.

Selective anti-cancer drug enhancements with therapeutic ultrasound

Continuous wave 1-MHz ultrasound at the therapeutic intensity of 1 W/cm2 was found to enhance significantly the hydroxyl radical production from two clinically employed redox cycling drugs, viz., Adriamycin (Doxorubicin) and Mitomycin C, with respect to the control drug-free insonicated phosphate buffer suspension. Benzoic acid (Bz) was employed as a sensitive chemical probe to detect hydroxyl radicals (OH⋅). Bz is initially nonfluorescent and upon aromatic hydroxylation becomes permanently fluorescent. A series of time course studies up to one-half hour were performed on drug suspensions to characterize the OH⋅ generation in the presence and absence of ultrasound at 37 °C. Identical ultrasound treatments on non-redox cycling clinical drugs 5-Fluorouracil and Methotrexate did not yield any significant enhancement in the production of OH⋅ in comparison to the drug-free insonicated phosphate buffer suspension. One-half hour ultrasound exposures did not yield measurable changes in the chemical constitution of the four drugs as assessed through high-pressure liquid chromatography. Identical ultrasound treatments at 3 MHz did not produce at OH⋅ in the presence or in the absence of these four anti-cancer drugs. Free radical scavengers such as mannitol, superoxide dismutase, catalase, and a transition metal chelating agent were employed independently to discern the chemical species and pathways involved in the production of the OH⋅. The findings strongly implicate an active role of acoustically induced cavitation in potentiating redox cycling drugs via chemical reduction and, thereafter, production of the OH⋅ via Fenton’s pathway.

Protein conformational changes and myelin solubilization by anion-detergent solutions

The addition of sodium sulfate to a myelin suspension in sodium phosphate buffer at neutral pH, containing octyl glucoside detergent (OG), increases the membrane solubility more than 5-fold by an unknown structural mechanism. FTIR spectroscopy has been applied to investigate anion effects on the conformational structure of myelin proteins. Sulfate and sulfate-phosphate media, but not phosphate alone, induce a great conformational protein disorder. The addition of the detergent to the anion mixture solution prevents the myelin from protein denaturation. The conformational transitions have also been quantified through the amide I region. Explanations of these changes and their connections with myelin solubility are also included.