Simple, sensitive, selective and validated spectrophotometric methods for the estimation of a biomarker trigonelline from polyherbal gels

NASA Astrophysics Data System (ADS)

Chopra, Shruti; Motwani, Sanjay K.; Ahmad, Farhan J.; Khar, Roop K.

2007-11-01

Simple, accurate, reproducible, selective, sensitive and cost effective UV-spectrophotometric methods were developed and validated for the estimation of trigonelline in bulk and pharmaceutical formulations. Trigonelline was estimated at 265 nm in deionised water and at 264 nm in phosphate buffer (pH 4.5). Beer's law was obeyed in the concentration ranges of 1-20 μg mL -1 ( r2 = 0.9999) in deionised water and 1-24 μg mL -1 ( r2 = 0.9999) in the phosphate buffer medium. The apparent molar absorptivity and Sandell's sensitivity coefficient were found to be 4.04 × 10 3 L mol -1 cm -1 and 0.0422 μg cm -2/0.001A in deionised water; and 3.05 × 10 3 L mol -1 cm -1 and 0.0567 μg cm -2/0.001A in phosphate buffer media, respectively. These methods were tested and validated for various parameters according to ICH guidelines. The detection and quantitation limits were found to be 0.12 and 0.37 μg mL -1 in deionised water and 0.13 and 0.40 μg mL -1 in phosphate buffer medium, respectively. The proposed methods were successfully applied for the determination of trigonelline in pharmaceutical formulations (vaginal tablets and bioadhesive vaginal gels). The results demonstrated that the procedure is accurate, precise, specific and reproducible (percent relative standard deviation <2%), while being simple and less time consuming and hence can be suitably applied for the estimation of trigonelline in different dosage forms and dissolution studies.

Dissolution properties of co-amorphous drug-amino acid formulations in buffer and biorelevant media.

PubMed

Heikkinen, A T; DeClerck, L; Löbmann, K; Grohganz, H; Rades, T; Laitinen, R

2015-07-01

Co-amorphous formulations, particularly binary drug-amino acid mixtures, have been shown to provide enhanced dissolution for poorly-soluble drugs and improved physical stability of the amorphous state. However, to date the dissolution properties (mainly intrinsic dissolution rate) of the co-amorphous formulations have been tested only in buffers and their supersaturation ability remain unexplored. Consequently, dissolution studies in simulated intestinal fluids need to be conducted in order to better evaluate the potential of these systems in increasing the oral bioavailability of biopharmaceutics classification system class II drugs. In this study, solubility and dissolution properties of the co-amorphous simvastatin-lysine, gibenclamide-serine, glibenclamide-threonine and glibenclamide-serine-threonine were studied in phosphate buffer pH 7.2 and biorelevant media (fasted and fed state simulated intestinal fluids (FaSSIF and FeSSIF, respectively)). The co-amorphous formulations were found to provide a long-lasting supersaturation and improve the dissolution of the drugs compared to the crystalline and amorphous drugs alone in buffer. Similar improvement, but in lesser extent, was observed in biorelevant media suggesting that a dissolution advantage observed in aqueous buffers may overestimate the advantage in vivo. However, the results show that, in addition to stability advantage shown earlier, co-amorphous drug-amino acid formulations provide dissolution advantage over crystalline drugs in both aqueous and biorelevant conditions.

Coaxial atomic force microscope probes for dielectrophoresis of DNA under different buffer conditions

NASA Astrophysics Data System (ADS)

Tao, Yinglei; Kumar Wickramasinghe, H.

2017-02-01

We demonstrate a coaxial AFM nanoprobe device for dielectrophoretic (DEP) trapping of DNA molecules in Tris-EDTA (TE) and phosphate-buffered saline (PBS) buffers. The DEP properties of 20 nm polystyrene beads were studied with coaxial probes in media with different conductivities. Due to the special geometry of our DEP probe device, sufficiently high electric fields were generated at the probe end to focus DNA molecules with positive DEP. DEP trapping for both polystyrene beads and DNA molecules was quantitatively analyzed over the frequency range from 100 kHz to 50 MHz and compared with the Clausius-Mossotti theory. Finally, we discussed the negative effect of medium salinity during DEP trapping.

Dominant oceanic bacteria secure phosphate using a large extracellular buffer

PubMed Central

Zubkov, Mikhail V.; Martin, Adrian P.; Hartmann, Manuela; Grob, Carolina; Scanlan, David J.

2015-01-01

The ubiquitous SAR11 and Prochlorococcus bacteria manage to maintain a sufficient supply of phosphate in phosphate-poor surface waters of the North Atlantic subtropical gyre. Furthermore, it seems that their phosphate uptake may counter-intuitively be lower in more productive tropical waters, as if their cellular demand for phosphate decreases there. By flow sorting 33P-phosphate-pulsed 32P-phosphate-chased cells, we demonstrate that both Prochlorococcus and SAR11 cells exploit an extracellular buffer of labile phosphate up to 5–40 times larger than the amount of phosphate required to replicate their chromosomes. Mathematical modelling is shown to support this conclusion. The fuller the buffer the slower the cellular uptake of phosphate, to the point that in phosphate-replete tropical waters, cells can saturate their buffer and their phosphate uptake becomes marginal. Hence, buffer stocking is a generic, growth-securing adaptation for SAR11 and Prochlorococcus bacteria, which lack internal reserves to reduce their dependency on bioavailable ambient phosphate. PMID:26198420

Preparation and Characterization of Amylose Inclusion Complexes for Drug Delivery Applications.

PubMed

Carbinatto, Fernanda M; Ribeiro, Tatiana S; Colnago, Luiz Alberto; Evangelista, Raul Cesar; Cury, Beatriz S F

2016-01-01

Amylose complexes with nimesulide (NMS) and praziquantel (PZQ) were prepared by a simple and low cost method, so that high yield (>57%) and drug content (up to 68.16%) were achieved. The influence of drug:polymer ratio, temperature, and presence of palmitic acid on the complexes properties was evaluated. Differential scanning calorimetry, X-ray diffraction, and nuclear magnetic resonance data evidenced the drug-polymer interaction and the formation of inclusion complexes with semi-crystalline structures related to type II complexes. The drug release rates from complexes were lowered in acid media (pH 1.2) and phosphate buffer (pH 6.9). The presence of pancreatin promoted a significant acceleration of the release rates of both drugs, evidencing the enzymatic degradability of these complexes. The highest enzymatic resistance of PZQ1:30PA60°C complex makes the release time longer and the full release of PZQ in phosphate buffer with pancreatin occurred at 240 min, whereas the complexes with NMS and PZQ1:5PA90°C did it in 60 min. According to the Weibull model, the drug release process in media without enzyme occurred by complex mechanisms involving diffusion, swelling, and erosion. In media containing pancreatin, generally, the better correlation was with the first order, evidencing the acceleration of the release rates of drugs in the early stages of the test, due to enzymatic degradation.

Microwave fixation versus formalin fixation of surgical and autopsy tissue.

PubMed

Login, G R

1978-05-01

Microwave irradiation of surgical and autopsy tissue penetrates, fixes, and hardens the tissue almost immediately (the fluid media used in the microwave consisted of saline, ten percent phosphate buffered formalin, and distilled water). Tissue sections from a representative sample of organs were tested. Comparable sections were simultaneously fixed in a phosphate buffered ten percent formalin bath in a vaccum oven as a control. Hematoxylin and eosin were used to stain the sections. Results equal to and superior to the control method were obtained. Saline microwave fixation was superior to formalin microwave fixation. Tissues placed in Zenker's solution and fixed in standard microwave oven (for approximately one minute) yielded results at least equal to conventional Zenker fixation (approximately two hours). No tissue hardening resulted from Zenker microwave fixation. A unique time versus temperature graph (microwave heating curve) reduces individual variation with this technique.

Influence of Dissolution Media and Presence of Alcohol on the In Vitro Performance of Pharmaceutical Products Containing an Insoluble Drug.

PubMed

Friuli, Valeria; Bruni, Giovanna; Musitelli, Giorgio; Conte, Ubaldo; Maggi, Lauretta

2018-01-01

The purpose of this investigation is to determine how the dissolution media may influence the release rate of an insoluble drug in in vitro conditions. Some oral dosage forms containing ibuprofen, a molecule that shows pH-dependent solubility, are tested. They are evaluated in different media to simulate the gastrointestinal transit at paddle rotation speeds of 50 and 100 rpm. Moreover, the potential effect of different ethanol concentrations on drug release is tested. The dissolution profiles of the tablets show a similar behavior in water (pH 1.0) and phosphate buffer (pH 4.5) where the 2 doses are not completely dissolved. The soft capsules show a different behavior: a certain amount of ibuprofen, which is in solution inside the capsule, reprecipitates in water and in the pH 4.5 buffer. Instead, ibuprofen dissolves rapidly in the pH 6.8 buffer from all the formulations. In the water-ethanol solutions, the dissolution curves show a valuable increase in the drug dissolved at higher ethanol concentrations. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Toward an In Vivo Dissolution Methodology: A Comparison of Phosphate and Bicarbonate Buffers

PubMed Central

Sheng, Jennifer J.; McNamara, Daniel P.; Amidon, Gordon L.

2011-01-01

Purpose To evaluate the difference between the pharmaceutical phosphate buffers and the gastrointestinal bicarbonates in dissolution of ketoprofen and indomethacin, to illustrate the dependence of buffer differential on biopharmaceutical properties of BCS II weak acids, and to recommend phosphate buffers equivalent to bicarbonates. Methods The intrinsic dissolution rates of, ketoprofen and indomethacin, were experimentally measured using rotating disk method at 37°C in USP SIF/FaSSIF and various concentrations of bicarbonates. Theoretical models including an improved reaction plane model and a film model were applied to estimate the surrogate phosphate buffers equivalent to the bicarbonates. Results Experimental results show that the intrinsic dissolution rates of ketoprofen and indomethacin, in USP and FaSSIF phosphate buffers are 1.5–3.0 times of that in the 15 mM bicarbonates. Theoretical analysis demonstrates that the buffer differential is largely dependent on the drug pKa and secondly on solubility, and weakly dependent on the drug diffusivity. Further, in accordance with the drug pKa, solubility and diffusivity, simple phosphate surrogate was proposed to match an average bicarbonate value (15 mM) of the upper gastrointestinal region. Specifically, phosphate buffers of 13–15 mM and 3–4 mM were recommended for ketoprofen and indomethacin, respectively. For both ketoprofen and indomethacin, the intrinsic dissolution using the phosphate surrogate buffers closely approximated the 15 mM bicarbonate buffer. Conclusions This work demonstrates the substantial difference between pharmaceutical phosphates and physiological bicarbonates in determining the drug intrinsic dissolution rates of BCS II weak acids, such as ketoprofen and indomethacin. Surrogate phosphates were recommended in order to closely reflect the in vivo dissolution of ketoprofen and indomethacin in gastrointestinal bicarbonates, which has significant implications for defining buffer systems for BCS II weak acids in developing in vitro bioequivalence dissolution methodology. PMID:19183104

Kinetics and mechanism of bacterial inactivation by ultrasound waves and sonoprotective effect of milk components.

PubMed

Gera, N; Doores, S

2011-03-01

Inactivation of Escherichia coli and Listeria monocytogenes were investigated in buffer and milk upon treatment with ultrasound waves (USW). In addition, sonoprotective effect of milk components and ultrasound-induced changes in bacterial cells were investigated using scanning electron microscopy (SEM). Bacterial cells were added to phosphate buffer, whole milk, skim milk, or simulated milk ultrafiltrate (SMUF). To determine the sonoprotective effect of milk components, lactose (5%), casein (3%), or β lactoglobulin (0.3%) was added to SMUF. Samples were sonicated with 24 kHz pulse USW while maintaining the system temperature between 30 to 35 °C. Aliquots were drawn at set times during sonication and bacteria were enumerated by surface plating appropriate dilutions on selective and nonselective media plates. Escherichia coli exhibited significantly higher D values in whole (2.43 min) and skim milk (2.41 min) than phosphate buffer (2.19 min). Listeria monocytogenes also showed higher D values in whole (9.31 min) and skim milk (8.61 min) compared to phosphate buffer (7.63 min). Data suggest that milk exerts a sonoprotective effect on these bacteria. Escherichia coli exhibited a log-linear inactivation kinetics followed by tailing whereas L. monocytogenes showed 1st-order kinetics throughout. Among the milk components tested, presence of lactose in SMUF resulted in significantly higher D values than SMUF for both organisms suggesting that lactose was exerting a protective effect on bacteria. SEM images showed that USW caused mechanical damage to the cell wall and cell membrane of bacteria leading to their inactivation.

Effects of coating layer and release medium on release profile from coated capsules with Eudragit FS 30D: an in vitro and in vivo study.

PubMed

Moghimipour, Eskandar; Rezaei, Mohsen; Kouchak, Maryam; Fatahiasl, Jafar; Angali, Kambiz Ahmadi; Ramezani, Zahra; Amini, Mohsen; Dorkoosh, Farid Abedin; Handali, Somayeh

2018-05-01

The aim of the present research was to evaluate the impact of coating layers on release profile from enteric coated dosage forms. Capsules were coated with Eudragit FS 30D using dipping method. The drug profile was evaluated in both phosphate buffer and Hank's solutions. Utilization X-ray imaging, gastrointestinal transmission of enteric coated capsules was traced in rats. According to the results, no release of the drug was found at pH 1.2, and the extent of release drug in pH 6.8 medium was decreased by adding the coating layers. The results indicated single-layer coated capsules in phosphate buffer were significantly higher than that in Hank's solution. However, no significant difference was observed from capsules with three coating layers in two different dissolution media. X-ray imaging showed that enteric coated capsules were intact in the stomach and in the small intestine, while disintegrated in the colon.

Comparative Analysis of Two Biological Warfare Air Samplers Using Live Surrogate Agents

DTIC Science & Technology

2012-03-01

extensively for Phosphate Buffer Saline (PBS) solution and water , and, to a very limited degree in AF evaluations, for virus preserving media, specifically...or water . Furthermore, viral studies have been conducted comparing the effectiveness of utilizing the reduced secondary flow rate on the XMX/2L...with using bioagent aerosols rated BSL-2 or higher. Male Specific Coliphage 2 (MS2), American Type Culture Collection (ATCC) 15597-B1, was selected

Chemometrics-assisted spectrophotometric green method for correcting interferences in biowaiver studies: Application to assay and dissolution profiling study of donepezil hydrochloride tablets

NASA Astrophysics Data System (ADS)

Korany, Mohamed A.; Mahgoub, Hoda; Haggag, Rim S.; Ragab, Marwa A. A.; Elmallah, Osama A.

2018-06-01

A green, simple and cost effective chemometric UV-Vis spectrophotometric method has been developed and validated for correcting interferences that arise during conducting biowaiver studies. Chemometric manipulation has been done for enhancing the results of direct absorbance, resulting from very low concentrations (high incidence of background noise interference) of earlier points in the dissolution timing in case of dissolution profile using first and second derivative (D1 & D2) methods and their corresponding Fourier function convoluted methods (D1/FF& D2/FF). The method applied for biowaiver study of Donepezil Hydrochloride (DH) as a representative model was done by comparing two different dosage forms containing 5 mg DH per tablet as an application of a developed chemometric method for correcting interferences as well as for the assay and dissolution testing in its tablet dosage form. The results showed that first derivative technique can be used for enhancement of the data in case of low concentration range of DH (1-8 μg mL-1) in the three different pH dissolution media which were used to estimate the low drug concentrations dissolved at the early points in the biowaiver study. Furthermore, the results showed similarity in phosphate buffer pH 6.8 and dissimilarity in the other 2 pH media. The method was validated according to ICH guidelines and USP monograph for both assays (HCl of pH 1.2) and dissolution study in 3 pH media (HCl of pH 1.2, acetate buffer of pH 4.5 and phosphate buffer of pH 6.8). Finally, the assessment of the method greenness was done using two different assessment techniques: National Environmental Method Index label and Eco scale methods. Both techniques ascertained the greenness of the proposed method.

Chemometrics-assisted spectrophotometric green method for correcting interferences in biowaiver studies: Application to assay and dissolution profiling study of donepezil hydrochloride tablets.

PubMed

Korany, Mohamed A; Mahgoub, Hoda; Haggag, Rim S; Ragab, Marwa A A; Elmallah, Osama A

2018-06-15

A green, simple and cost effective chemometric UV-Vis spectrophotometric method has been developed and validated for correcting interferences that arise during conducting biowaiver studies. Chemometric manipulation has been done for enhancing the results of direct absorbance, resulting from very low concentrations (high incidence of background noise interference) of earlier points in the dissolution timing in case of dissolution profile using first and second derivative (D1 & D2) methods and their corresponding Fourier function convoluted methods (D1/FF& D2/FF). The method applied for biowaiver study of Donepezil Hydrochloride (DH) as a representative model was done by comparing two different dosage forms containing 5mg DH per tablet as an application of a developed chemometric method for correcting interferences as well as for the assay and dissolution testing in its tablet dosage form. The results showed that first derivative technique can be used for enhancement of the data in case of low concentration range of DH (1-8μgmL -1 ) in the three different pH dissolution media which were used to estimate the low drug concentrations dissolved at the early points in the biowaiver study. Furthermore, the results showed similarity in phosphate buffer pH6.8 and dissimilarity in the other 2pH media. The method was validated according to ICH guidelines and USP monograph for both assays (HCl of pH1.2) and dissolution study in 3pH media (HCl of pH1.2, acetate buffer of pH4.5 and phosphate buffer of pH6.8). Finally, the assessment of the method greenness was done using two different assessment techniques: National Environmental Method Index label and Eco scale methods. Both techniques ascertained the greenness of the proposed method. Copyright © 2018 Elsevier B.V. All rights reserved.

Phosphate and HEPES buffers potently affect the fibrillation and oligomerization mechanism of Alzheimer's A{beta} peptide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Garvey, Megan; Tepper, Katharina; Haupt, Caroline

Highlights: {yields} Sodium phosphate buffer accelerated A{beta}(1-40) nucleation relative to HEPES. {yields} A{beta}(1-40) fibrils formed in the two buffers show only minor structural differences. {yields} NMR revealed that A{beta}(1-40) histidine residues mediate buffer dependent changes. -- Abstract: The oligomerization of A{beta} peptide into amyloid fibrils is a hallmark of Alzheimer's disease. Due to its biological relevance, phosphate is the most commonly used buffer system for studying the formation of A{beta} and other amyloid fibrils. Investigation into the characteristics and formation of amyloid fibrils frequently relies upon material formed in vitro, predominantly in phosphate buffers. Herein, we examine the effects onmore » the fibrillation and oligomerization mechanism of A{beta} peptide that occur due solely to the influence of phosphate buffer. We reveal that significant differences in amyloid fibrillation are observed due to fibrillation being initiated in phosphate or HEPES buffer (at physiological pH and temperature). Except for the differing buffer ions, all experimental parameters were kept constant. Fibril formation was assessed using fluorescently monitored kinetic studies, microscopy, X-ray fiber diffraction and infrared and nuclear magnetic resonance spectroscopies. Based on this set up, we herein reveal profound effects on the mechanism and speed of A{beta} fibrillation. The three histidine residues at positions 6, 13 and 14 of A{beta}(1-40) are instrumental in these mechanistic changes. We conclude that buffer plays a more significant role in fibril formation than has been generally acknowledged.« less

Antitumour, antimicrobial and catalytic activity of gold nanoparticles synthesized by different pH propolis extracts

NASA Astrophysics Data System (ADS)

Gatea, Florentina; Teodor, Eugenia Dumitra; Seciu, Ana-Maria; Covaci, Ovidiu Ilie; Mănoiu, Sorin; Lazăr, Veronica; Radu, Gabriel Lucian

2015-07-01

The Romanian propolis was extracted in five different media, respectively, in water (pH 6.8), glycine buffer (pH 2.5), acetate buffer (pH 5), phosphate buffer (pH 7.4) and carbonate buffer (pH 9.2). The extracts presented different amounts of flavonoids and phenolic acids, increasing pH leading to higher concentrations of active compounds. Five variants of gold nanoparticles suspensions based on different pH Romanian propolis aqueous extracts were successfully synthesized. The obtained nanoparticles presented dimensions between 20 and 60 nm in dispersion form and around 18 nm in dried form, and different morphologies (spherical, hexagonal, triangular). Fourier transform infrared spectroscopy proved the attachment of organic compounds from propolis extracts to the colloidal gold suspensions and X-ray diffraction certified that the suspensions contain metallic gold. The obtained propolis gold nanoparticles do not exhibit any antibacterial or antifungal activity, but presented different catalytic activities and toxicity on tumour cells.

Determination of residual cell culture media components by MEKC.

PubMed

Zhang, Junge; Chakraborty, Utpal; Foley, Joe P

2009-11-01

Folic acid, hypoxanthine, mycophenolic acid, nicotinic acid, riboflavin, and xanthine are widely used as cell culture media components in monoclonal antibody manufacturing. These components are subsequently removed during the downstream purification processes. This article describes a single MEKC method that can simultaneously determine all the listed compounds with acceptable LOD and LOQ. All the analytes were successfully separated by MEKC using running buffer containing 40 mM SDS, 20 mM sodium phosphate, and 20 mM sodium borate at pH 9.0. The MEKC method was compared to the corresponding CZE method using the same running buffer containing no SDS. The effect of SDS concentration on separation, the pH of the running buffer, and the detection wavelength were studied and optimal MEKC conditions were established. Good linearity was obtained with correlation coefficients of more than 0.99 for all analytes. Specificity, accuracy, and precision were also evaluated. The recovery was in the range of 89-112%. The precision results were in the range of 1.7-4.8%. The experimentally determined data demonstrated that the MEKC method is applicable to the determination of the six analytes in in-process samples from monoclonal antibody manufacturing processes.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G.; White, S. M.

2012-12-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg l-1 to 0.061 mg l-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Phosphorus sorption and buffering mechanisms in suspended sediments from the Yangtze Estuary and Hangzhou Bay, China

NASA Astrophysics Data System (ADS)

Li, M.; Whelan, M. J.; Wang, G. Q.; White, S. M.

2013-05-01

The adsorption isotherm and the mechanism of the buffering effect are important controls on phosphorus (P) behaviors in estuaries and are important for estimating phosphate concentrations in aquatic environments. In this paper, we derive phosphate adsorption isotherms in order to investigate sediment adsorption and buffering capacity for phosphorus discharged from sewage outfalls in the Yangtze Estuary and Hangzhou Bay near Shanghai, China. Experiments were also carried out at different temperatures in order to explore the buffering effects for phosphate. The results show that P sorption in sediments with low fine particle fractions was best described using exponential equations. Some P interactions between water and sediment may be caused by the precipitation of CaHPO4 from Ca2+ and HPO42- when the phosphate concentration in the liquid phase is high. Results from the buffering experiments suggest that the Zero Equilibrium Phosphate Concentrations (EPC0) vary from 0.014 mg L-1 to 0.061 mg L-1, which are consistent with measured phosphate concentrations in water samples collected at the same time as sediment sampling. Values of EPC0 and linear sorption coefficients (K) in sediments with high fine particle and organic matter contents are relatively high, which implies that they have high buffering capacity. Both EPC0 and K increase with increasing temperature, indicating a higher P buffering capacity at high temperatures.

Effect of glycine on pH changes and protein stability during freeze-thawing in phosphate buffer systems.

PubMed

Pikal-Cleland, Katherine A; Cleland, Jeffrey L; Anchordoquy, Thomas J; Carpenter, John F

2002-09-01

Previous studies have established that the selective precipitation of a less soluble buffer component during freezing can induce a significant pH shift in the freeze concentrate. During freezing of sodium phosphate solutions, crystallization of the disodium salt can produce a pH decrease as great as 3 pH units which can dramatically affect protein stability. The objective of our study was to determine how the presence of glycine (0-500 mM), a commonly used bulking agent in pharmaceutical protein formulations, affects the pH changes normally observed during freezing in sodium phosphate buffer solutions and to determine whether these pH changes contribute to instability of model proteins in glycine/phosphate formulations. During freezing in sodium phosphate buffers, the presence of glycine significantly influenced the pH. Glycine at the lower concentrations (< or = 50 mM) suppressed the pH decrease normally observed during freezing in 10 and 100 mM sodium phosphate buffer, possibly by reducing the nucleation rate of salt and thereby decreasing the extent of buffer salt crystallization. The presence of glycine at higher concentration (> 100 mM) in the sodium phosphate buffer resulted in a more complete crystallization of the disodium salt as indicated by the frozen pH values closer to the equilibrium value (pH 3.6). Although high concentrations of glycine can facilitate more buffer salt crystallization and these pH shifts may prove to be potentially damaging to the protein, glycine, in its amorphous state, can also act to stabilize a protein via the preferential exclusion mechanism. Copyright 2002 Wiley-Liss Inc.

Magnesium coated phosphate glass fibers for unidirectional reinforcement of polycaprolactone composites.

PubMed

Liu, Xiaoling; Grant, David M; Palmer, Graham; Parsons, Andrew J; Rudd, Chris D; Ahmed, Ifty

2015-10-01

Bioresorbable composites have shown much potential for bone repair applications, as they have the ability to degrade completely over time and their degradation and mechanical properties can be tailored to suit the end application. In this study, phosphate glass fiber (from the system 45% P2 O5-16% CaO-24% MgO-11% Na2 O-4% Fe2 O3 (given in mol%)) were used to reinforce polycaprolactone (PCL) with approximately 20% fiber volume fraction. The glass fiber surfaces were coated with magnesium (Mg) through magnetron sputtering to improve the fiber-matrix interfacial properties. The Mg coating provided a rough fiber surface (roughness (Ra) of about 44nm). Both noncoated and Mg-coated fiber-reinforced composites were assessed. The water uptake and mass loss properties for the composites were assessed in phosphate-buffered saline (PBS) at 37°C for up to 28 days, and ion release profiles were also investigated in both water and PBS media. Inhibition of media influx was observed for the Mg-coated composites. The composite mechanical properties were characterized on the basis of both tensile and flexural tests and their retention in PBS media at 37°C was also investigated. A higher retention of the mechanical properties was observed for the Mg-coated composites over the 28 days degradation period. © 2014 Wiley Periodicals, Inc.

Growth of calcium phosphates on magnesium substrates for corrosion control in biomedical applications via immersion techniques.

PubMed

Shadanbaz, Shaylin; Walker, Jemimah; Staiger, Mark P; Dias, George J; Pietak, Alexis

2013-01-01

Magnesium (Mg) has been suggested as a revolutionary biodegradable replacement for current permanent metals used in orthopedic applications. Current investigations concentrate on the control of the corrosion rate to match bone healing. Calcium phosphate coatings have been a recent focus of these investigations through various coating protocols. Within this investigation, an in situ crystallization technique was utilized as an inexpensive and relatively simple method to produce a brushite and monetite coating on pure Mg. Coatings were characterized using energy dispersive spectroscopy, glancing angle X-ray diffraction and field emission scanning electron microscopy. Corrosion protection properties of the coatings were assessed in physiological buffers, Earles balanced salt solution, minimum essential media, and minimum essential media containing serum albumin, over a 4-week period. Using this novel coating protocol, our findings indicate brushite and monetite coated Mg to have significant corrosive protective effects when compared with its uncoated counterpart whilst maintaining high coating substrate adhesion, homogeneity, and reproducibility. Copyright © 2012 Wiley Periodicals, Inc.

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate.

PubMed

Kawasaki, Kosei; Kamagata, Yoichi

2017-11-01

Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H 2 O 2 ) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659-7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H 2 O 2 formation in agar. The H 2 O 2 formation was pH dependent: H 2 O 2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H 2 O 2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H 2 O 2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H 2 O 2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H 2 O 2 from PT medium, these observations indicate that although H 2 O 2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H 2 O 2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H 2 O 2 formation from agar. H 2 O 2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H 2 O 2 formation. Amendment of catalase or pyruvate, a well-known H 2 O 2 -scavenging agent, effectively eliminated H 2 O 2 Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. Copyright © 2017 American Society for Microbiology.

Phosphate-Catalyzed Hydrogen Peroxide Formation from Agar, Gellan, and κ-Carrageenan and Recovery of Microbial Cultivability via Catalase and Pyruvate

PubMed Central

Kamagata, Yoichi

2017-01-01

ABSTRACT Previously, we reported that when agar is autoclaved with phosphate buffer, hydrogen peroxide (H2O2) is formed in the resulting medium (PT medium), and the colony count on the medium inoculated with environmental samples becomes much lower than that on a medium in which agar and phosphate are autoclaved separately (PS medium) (T. Tanaka et al., Appl Environ Microbiol 80:7659–7666, 2014, https://doi.org/10.1128/AEM.02741-14). However, the physicochemical mechanisms underlying this observation remain largely unknown. Here, we determined the factors affecting H2O2 formation in agar. The H2O2 formation was pH dependent: H2O2 was formed at high concentrations in an alkaline or neutral phosphate buffer but not in an acidic buffer. Ammonium ions enhanced H2O2 formation, implying the involvement of the Maillard reaction catalyzed by phosphate. We found that other gelling agents (e.g., gellan and κ-carrageenan) also produced H2O2 after being autoclaved with phosphate. We then examined the cultivability of microorganisms from a fresh-water sample to test whether catalase and pyruvate, known as H2O2 scavengers, are effective in yielding high colony counts. The colony count on PT medium was only 5.7% of that on PS medium. Catalase treatment effectively restored the colony count of PT medium (to 106% of that on PS medium). In contrast, pyruvate was not as effective as catalase: the colony count on sodium pyruvate-supplemented PT medium was 58% of that on PS medium. Given that both catalase and pyruvate can remove H2O2 from PT medium, these observations indicate that although H2O2 is the main cause of reduced colony count on PT medium, other unknown growth-inhibiting substances that cannot be removed by pyruvate (but can be by catalase) may also be involved. IMPORTANCE The majority of bacteria in natural environments are recalcitrant to laboratory culture techniques. Previously, we demonstrated that one reason for this is the formation of high H2O2 levels in media prepared by autoclaving agar and phosphate buffer together (PT medium). In this study, we investigated the factors affecting H2O2 formation from agar. H2O2 formation is pH dependent, and ammonium ions promote this phosphate-catalyzed H2O2 formation. Amendment of catalase or pyruvate, a well-known H2O2-scavenging agent, effectively eliminated H2O2. Yet results suggest that growth-inhibiting factor(s) that cannot be eliminated by pyruvate (but can be by catalase) are present in PT medium. PMID:28821549

Buffer Effects in the Solubility, Nucleation and Growth of Chicken Egg White Lysozyme

NASA Technical Reports Server (NTRS)

Gibson, Ursula J.

1999-01-01

The growth of protein crystals is important for determination of their three-dimensional structure, which relates to their biochemical functions and to the practical goal of designing pharmaceuticals to modify that function. While many proteins have been successfully crystallized by a variety of methods, there is still limited understanding of the process of nucleation and growth of even the simplest proteins. Chicken egg-white lysozyme (CEWL) is readily crystallized under a variety of conditions, and studies underway at MSFC are designed to elucidate the mechanisms by which the crystals nucleate and grow. We have investigated the effect of buffer choice on the solubility, nucleation and growth of CEWL. CEWL was purified by dialysis against a .05M phosphate buffer and chromatographic separation from contaminants in a sepharose column. Solubility studies were made as a function of buffer concentration for phosphate and formate buffers, and the nucleation and growth of crystals at 10 C was studied as a function of pH for oxalate, succinate, formate, butyrate, carbonate, phosphate and acetate buffer solutions. The solubility data support the conclusion that there is a solubility minimum as a function of buffer concentration for amphiphilic molecules, while no minimum is observed for a phosphate buffer. Nucleation is suppressed at pH greater than pKa for all buffers except phosphate. The aspect ratio of the (110) faces is shown to be a function of crystal size, rather than pH.

Time-related Changes in pH, Buffering Capacity and Phosphate and Urea Concentration of Stimulated Saliva.

PubMed

Vuletic, Lea; Peros, Kristina; Spalj, Stjepan; Rogic, Dunja; Alajbeg, Ivan

2014-01-01

To quantify changes in pH, buffering capacity and hydrogen carbonate, phosphate, protein and urea concentrations of stimulated saliva which occur during a 30-min measurement delay after saliva collection. The correlation between time-related chemical changes and changes of salivary pH and buffering capacity was assessed in order to explain the observed changes in salivary pH and buffering capacity. Stimulated saliva samples were collected from 30 volunteers after inducing salivation by chewing a piece of parafilm. Measurements of salivary variables were made immediately after saliva collection and again 30 min later, during which time the specimens were exposed to the atmosphere in collection cups at room temperature. Postponement of measurements resulted in a significant increase in pH and a significant decrease of buffering capacity, phosphate and urea concentration. The results suggest that the time-related pH increase could primarily be attributed to loss of dissolved carbon dioxide from saliva, and confirm the importance of hydrogen carbonate in the neutralisation of hydrogen ions, but they do not support the principle of catalysed phase-buffering for the hydrogen carbonate buffer system in saliva. A decrease in phosphate and urea concentration affects salivary buffering capacity. This study emphasises the importance of the standardisation of measurement time when measuring salivary pH, buffering capacity, phosphate and urea concentrations following the collection of saliva in order to obtain comparable results. It also provides a partial explanation of the mechanisms underlying the observed changes of pH and buffering capacity over time.

Development of gastro intestinal sustained release tablet formulation containing acryl-EZE and pH-dependent swelling HPMC K 15 M.

PubMed

Lamoudi, Lynda; Chaumeil, Jean Claude; Daoud, Kamel

2012-05-01

The aim of this study was to evaluate physical properties and release from matrix tablets containing different ratios of HPMC 15 M and Acryl-EZE. A further aim is to assess their suitability for pH dependent controlled release. Matrix tablets containing HPMC 15 M and Acryl-EZE were manufactured using a fluidized bed. The release from this matrix using Sodium Diclofenac (SD) as model drug is studied in two dissolution media (0.1 N HCl or pH = 6.8 phosphate buffer solution); the release rate, mechanism, and pH dependence were characterized by fitting four kinetic models and by using a similarity factor analysis. The obtained results revealed that the presence of Acryl-EZE in the matrix tablets is effective in protecting the dosage forms from release in acid environments such as gastric fluid. In pH = 6.8 phosphate buffer, the drug release rate and mechanism of release from all matrices is mainly controlled by HPMC 15 M. The model of Korsmeyer-Peppas was found to fit experimental dissolution results.

Solubility of ammonium acid urate nephroliths from bottlenose dolphins (Tursiops truncatus).

PubMed

Argade, Sulabha; Smith, Cynthia R; Shaw, Timothy; Zupkas, Paul; Schmitt, Todd L; Venn-Watson, Stephanie; Sur, Roger L

2013-12-01

Nephrolithiasis has been identified in managed populations of bottlenose dolphins (Tursiops truncatus); most of these nephroliths are composed of 100% ammonium acid urate (AAU). Several therapies are being investigated to treat and prevent nephrolithiasis in dolphins including the alkalization of urine for dissolution of nephroliths. This study evaluates the solubility of AAU nephroliths in a phosphate buffer, pH range 6.0-8.0, and in a carbonate-bicarbonate buffer, pH range 9.0-10.8. AAU nephroliths were obtained from six dolphins and solubility studies were conducted using reverse-phase high performance liquid chromatography with ultraviolet detection at 290 nm. AAU nephroliths were much more soluble in a carbonate-bicarbonate buffer, pH range 9.0-10.8 compared to phosphate buffer pH range 6.0-8.0. In the pH range 6.0-8.0, the solubility was 45% lower in potassium phosphate buffer compared to sodium phosphate buffer. When citrate was used along with phosphate in the same pH range, the solubility was improved by 13%. At pH 7 and pH 8, 150 mM ionic strength buffer was optimum for dissolution. In summary, adjustment of urinary pH alone does not appear to be a useful way to treat AAU stones in bottlenose dolphins. Better understanding of the pathophysiology of AAU nephrolithiasis in dolphins is needed to optimize kidney stone prevention and treatment.

Aluminum elution and precipitation in glass vials: effect of pH and buffer species.

PubMed

Ogawa, Toru; Miyajima, Makoto; Wakiyama, Naoki; Terada, Katsuhide

2015-02-01

Inorganic extractables from glass vials may cause particle formation in the drug solution. In this study, the ability of eluting Al ion from borosilicate glass vials, and tendencies of precipitation containing Al were investigated using various pHs of phosphate, citrate, acetate and histidine buffer. Through heating, all of the buffers showed that Si and Al were eluted from glass vials in ratios almost the same as the composition of borosilicate glass, and the amounts of Al and Si from various buffer solutions at pH 7 were in the following order: citrate > phosphate > acetate > histidine. In addition, during storage after heating, the Al concentration at certain pHs of phosphate and acetate buffer solution decreased, suggesting the formation of particles containing Al. In citrate buffer, Al did not decrease in spite of the high elution amount. Considering that the solubility profile of aluminum oxide and the Al eluting profile of borosilicate glass were different, it is speculated that Al ion may be forced to leach into the buffer solution according to Si elution on the surface of glass vials. When Al ions were added to the buffer solutions, phosphate, acetate and histidine buffer showed a decrease of Al concentration during storage at a neutral range of pHs, indicating the formation of particles containing Al. In conclusion, it is suggested that phosphate buffer solution has higher possibility of forming particles containing Al than other buffer solutions.

Photo-degradation behaviour of roseoflavin in some aqueous solutions

NASA Astrophysics Data System (ADS)

Tyagi, A.; Penzkofer, A.; Mathes, T.; Hegemann, P.

2010-03-01

An absorption and emission spectroscopic characterization of roseoflavin (8-dimethylamino-8-demethyl-riboflavin, RoF) in aqueous solutions was carried out. The studies were concentrated on roseoflavin in pH 8 phosphate buffer. Absorption cross-section spectra, fluorescence excitation spectra, fluorescence quantum distributions, fluorescence quantum yields and fluorescence lifetimes were determined. The fluorescence of RoF is quenched by photo-induced intra-molecular charge-transfer at room temperature. The photo-degradation of RoF in un-buffered water, in Tris-HCl buffer, and in phosphate buffer was studied. Phosphate buffer and to a smaller extent Tris buffer catalyse the RoF photo-degradation. Photo-excitation of the primary photoproduct, 8-methylamino-riboflavin (8-MNH-RF), enhanced the RoF degradation by triplet 8-MNH-RF - singlet RoF excitation transfer with subsequent triplet-state RoF degradation.

Buffer Modulation of Menadione-Induced Oxidative Stress in Saccharomyces cerevisiae

PubMed Central

Lushchak, Oleh V.; Bayliak, Maria M.; Korobova, Olha V.; Levine, Rodney L.; Lushchak, Volodymyr I.

2012-01-01

The objective of this study was to compare in vivo the effects of bicarbonate and phosphate buffers on surviving and menadione-induced oxidative stress in yeast cells. The latter were treated with different concentrations of menadione in the presence of these two buffers. If at 25 mM concentration of buffers menadione only slightly reduced yeast surviving, at 50 mM concentration cell killing by menadione was much more pronounced in bicarbonate than in phosphate buffer. Although the content of protein carbonyl groups did not show development of oxidative stress under menadione-induced stress, inactivation of aconitase and decrease in glutathione level mirrored its induction. However, cellular glutathione and aconitase activity decrease did not correlate with yeast survival. In vitro, aconitase was more quickly inactivated in 50 mM carbonate, than in 50 mM phosphate buffer. The possible involvement of the carbonate radical in these processes is discussed. PMID:19843376

Buffer modulation of menadione-induced oxidative stress in Saccharomyces cerevisiae.

PubMed

Lushchak, Oleh V; Bayliak, Maria M; Korobova, Olha V; Levine, Rodney L; Lushchak, Volodymyr I

2009-01-01

The objective of this study was to compare, in vivo, the effects of bicarbonate and phosphate buffers on survival and menadione-induced oxidative stress in yeast cells. The latter were treated with different concentrations of menadione in the presence of these two buffers. At 25 mM concentration of buffers, menadione only slightly reduced yeast surviving; at 50 mM concentration, cell killing by menadione was much more pronounced in bicarbonate than in phosphate buffer. Although the content of protein carbonyl groups did not show development of oxidative stress under menadione-induced stress, inactivation of aconitase and decrease in glutathione level mirrored its induction. However, cellular glutathione and aconitase activity decrease did not correlate with yeast survival. In vitro, aconitase was more quickly inactivated in 50 mM carbonate, than in 50 mM phosphate buffer. The possible involvement of the carbonate radical in these processes is discussed.

Three dimensional graphene transistor for ultra-sensitive pH sensing directly in biological media.

PubMed

Ameri, Shideh Kabiri; Singh, Pramod K; Sonkusale, Sameer R

2016-08-31

In this work, pH sensing directly in biological media using three dimensional liquid gated graphene transistors is presented. The sensor is made of suspended network of graphene coated all around with thin layer of hafnium oxide (HfO2), showing high sensitivity and sensing beyond the Debye-screening limit. The performance of the pH sensor is validated by measuring the pH of isotonic buffered, Dulbecco's phosphate buffered saline (DPBS) solution, and of blood serum derived from Sprague-Dawley rat. The pH sensor shows high sensitivity of 71 ± 7 mV/pH even in high ionic strength media with molarities as high as 289 ± 1 mM. High sensitivity of this device is owing to suspension of three dimensional graphene in electrolyte which provides all around liquid gating of graphene, leading to higher electrostatic coupling efficiency of electrolyte to the channel and higher gating control of transistor channel by ions in the electrolyte. Coating graphene with hafnium oxide film (HfO2) provides binding sites for hydrogen ions, which results in higher sensitivity and sensing beyond the Debye-screening limit. The 3D graphene transistor offers the possibility of real-time pH measurement in biological media without the need for desaltation or sample preparation. Copyright © 2016 Elsevier B.V. All rights reserved.

The protective effect of supplemental calcium on colonic permeability depends on a calcium phosphate-induced increase in luminal buffering capacity.

PubMed

Schepens, Marloes A A; ten Bruggencate, Sandra J M; Schonewille, Arjan J; Brummer, Robert-Jan M; van der Meer, Roelof; Bovee-Oudenhoven, Ingeborg M J

2012-04-01

An increased intestinal permeability is associated with several diseases. Previously, we have shown that dietary Ca decreases colonic permeability in rats. This might be explained by a calcium-phosphate-induced increase in luminal buffering capacity, which protects against an acidic pH due to microbial fermentation. Therefore, we investigated whether dietary phosphate is a co-player in the effect of Ca on permeability. Rats were fed a humanised low-Ca diet, or a similar diet supplemented with Ca and containing either high, medium or low phosphate concentrations. Chromium-EDTA was added as an inert dietary intestinal permeability marker. After dietary adaptation, short-chain fructo-oligosaccharides (scFOS) were added to all diets to stimulate fermentation, acidify the colonic contents and induce an increase in permeability. Dietary Ca prevented the scFOS-induced increase in intestinal permeability in rats fed medium- and high-phosphate diets but not in those fed the low-phosphate diet. This was associated with higher faecal water cytotoxicity and higher caecal lactate levels in the latter group. Moreover, food intake and body weight during scFOS supplementation were adversely affected by the low-phosphate diet. Importantly, luminal buffering capacity was higher in rats fed the medium- and high-phosphate diets compared with those fed the low-phosphate diet. The protective effect of dietary Ca on intestinal permeability is impaired if dietary phosphate is low. This is associated with a calcium phosphate-induced increase in luminal buffering capacity. Dragging phosphate into the colon and thereby increasing the colonic phosphate concentration is at least part of the mechanism behind the protective effect of Ca on intestinal permeability.

Studies on the electrochemical behavior of thiazolidine and its applications using a flow-through chronoamperometric sensor based on a gold electrode.

PubMed

Wang, Lai-Hao; Li, Wen-Jie

2011-09-06

The electrochemical behaviors of thiazolidine (tetrahydrothiazole) on gold and platinum electrodes were investigated in a Britton-Robinson buffer (pH 2.77-11.61), acetate buffer (pH 4.31), phosphate buffer solutions (pH 2.11 and 6.38) and methanol or acetonitrile containing various supporting electrolytes. Detection was based on a gold wire electrochemical signal obtained with a supporting electrolyte containing 20% methanol-1.0 mM of phosphate buffer (pH 6.87, potassium dihydrogen phosphate and dipotassium hydrogen phosphate) as the mobile phase. Comparison with results obtained with a commercial amperometric detector shows good agreement. Using the chronoamperometric sensor with the current at a constant potential, and measurements with suitable experimental parameters, a linear concentration from 0.05 to 16 mg L-1 was found. The limit of quantification (LOQ) of the method for thiazolidine was found to be 1 ng.

Tris-sucrose buffer system: a new specially designed medium for extracellular invertase production by immobilized cells of isolated yeast Cryptococcus laurentii MT-61.

PubMed

Aydogan, Mehmet Nuri; Taskin, Mesut; Canli, Ozden; Arslan, Nazli Pinar; Ortucu, Serkan

2014-01-01

The aims of the present study were to isolate new yeasts with high extracellular (exo) invertase activity and to investigate the usability of buffer systems as invertase production media by immobilized yeast cells. Among 70 yeast isolates, Cryptococcus laurentii MT-61 had the highest exo-invertase activity. Immobilization of yeast cells was performed using sodium alginate. Higher exo-invertase activity for immobilized cells was achieved in tris-sucrose buffer system (TSBS) compared to sodium acetate buffer system and potassium phosphate buffer system. TSBS was prepared by dissolving 30 g of sucrose in 1 L of tris buffer solution. The optimum pH, temperature, and incubation time for invertase production with immobilized cells were determined as 8.0, 35 °C and 36 h in TSBS, respectively. Under optimized conditions, maximum exo-invertase activity was found to be 28.4 U/mL in sterile and nonsterile TSBS. Immobilized cells could be reused in 14 and 12 successive cycles in sterile and nonsterile TSBS without any loss in the maximum invertase activity, respectively. This is the first report which showed that immobilized microbial cells could be used as a biocatalyst for exo-invertase production in buffer system. As an additional contribution, a new yeast strain with high invertase activity was isolated.

Development and Validation of Different Ultraviolet-Spectrophotometric Methods for the Estimation of Besifloxacin in Different Simulated Body Fluids.

PubMed

Singh, C L; Singh, A; Kumar, S; Kumar, M; Sharma, P K; Majumdar, D K

2015-01-01

In the present study a simple, accurate, precise, economical and specific UV-spectrophotometric method for estimation of besifloxacin in bulk and in different pharmaceutical formulation has been developed. The drug shows maximum λmax289 nm in distilled water, simulated tears and phosphate buffer saline. The linearity range of developed methods were in the range of 3-30 μg/ml of drug with a correlation coefficient (r(2)) 0.9992, 0.9989 and 0.9984 with respect to distilled water, simulated tears and phosphate buffer saline, respectively. Reproducibility by repeating methods as %RSD were found to be less than 2%. The limit of detection in different media was found to be 0.62, 0.72 and 0.88 μg/ml, respectively. The limit of quantification was found to be 1.88, 2.10, 2.60 μg/ml, respectively. The proposed method was validated statically according to International Conference on Harmonization guidelines with respect to specificity, linearity, range, accuracy, precision and robustness. The proposed methods of validation were found to be accurate and highly specific for the estimation of besifloxacin in different pharmaceutical formulations.

In Vivo Predictive Dissolution: Comparing the Effect of Bicarbonate and Phosphate Buffer on the Dissolution of Weak Acids and Weak Bases.

PubMed

Krieg, Brian J; Taghavi, Seyed Mohammad; Amidon, Gordon L; Amidon, Gregory E

2015-09-01

Bicarbonate is the main buffer in the small intestine and it is well known that buffer properties such as pKa can affect the dissolution rate of ionizable drugs. However, bicarbonate buffer is complicated to work with experimentally. Finding a suitable substitute for bicarbonate buffer may provide a way to perform more physiologically relevant dissolution tests. The dissolution of weak acid and weak base drugs was conducted in bicarbonate and phosphate buffer using rotating disk dissolution methodology. Experimental results were compared with the predicted results using the film model approach of (Mooney K, Mintun M, Himmelstein K, Stella V. 1981. J Pharm Sci 70(1):22-32) based on equilibrium assumptions as well as a model accounting for the slow hydration reaction, CO2 + H2 O → H2 CO3 . Assuming carbonic acid is irreversible in the dehydration direction: CO2 + H2 O ← H2 CO3 , the transport analysis can accurately predict rotating disk dissolution of weak acid and weak base drugs in bicarbonate buffer. The predictions show that matching the dissolution of weak acid and weak base drugs in phosphate and bicarbonate buffer is possible. The phosphate buffer concentration necessary to match physiologically relevant bicarbonate buffer [e.g., 10.5 mM (HCO3 (-) ), pH = 6.5] is typically in the range of 1-25 mM and is very dependent upon drug solubility and pKa . © 2015 Wiley Periodicals, Inc. and the American Pharmacists Association.

Effect of bicarbonate on iron-mediated oxidation of low-density lipoprotein

NASA Astrophysics Data System (ADS)

Arai, Hirofumi; Berlett, Barbara S.; Chock, P. Boon; Stadtman, Earl R.

2005-07-01

Oxidation of low-density lipoprotein (LDL) may play an important role in atherosclerosis. We studied the effects of bicarbonate/CO2 and phosphate buffer systems on metal ion-catalyzed oxidation of LDL to malondialdehyde (MDA) and to protein carbonyl and MetO derivatives. Our results revealed that LDL oxidation in mixtures containing free iron or heme derivatives was much greater in bicarbonate/CO2 compared with phosphate buffer. However, when copper was substituted for iron in these mixtures, the rate of LDL oxidation in both buffers was similar. Iron-catalyzed oxidation of LDL was highly sensitive to inhibition by phosphate. Presence of 0.3-0.5 mM phosphate, characteristic of human serum, led to 30-40% inhibition of LDL oxidation in bicarbonate/CO2 buffer. Iron-catalyzed oxidation of LDL to MDA in phosphate buffer was inhibited by increasing concentrations of albumin (10-200 μM), whereas MDA formation in bicarbonate/CO2 buffer was stimulated by 10-50 μM albumin but inhibited by higher concentrations. However, albumin stimulated the oxidation of LDL proteins to carbonyl derivatives at all concentrations examined in both buffers. Conversion of LDL to MDA in bicarbonate/CO2 buffer was greatly stimulated by ADP, ATP, and EDTA but only when EDTA was added at a concentration equal to that of iron. At higher than stoichiometric concentrations, EDTA prevented oxidation of LDL. Results of these studies suggest that interactions between bicarbonate and iron or heme derivatives leads to complexes with redox potentials that favor the generation of reactive oxygen species and/or to the generation of highly reactive CO2 anion or bicarbonate radical that facilitates LDL oxidation. Freely available online through the PNAS open access option.Abbreviations: LDL, low-density lipoprotein; MDA, malondialdehyde; MetO, methionine sulfoxide.

Transport of viruses through saturated and unsaturated columns packed with sand

USGS Publications Warehouse

Anders, R.; Chrysikopoulos, C.V.

2009-01-01

Laboratory-scale virus transport experiments were conducted in columns packed with sand under saturated and unsaturated conditions. The viruses employed were the male-specific RNA coliphage, MS2, and the Salmonella typhimurium phage, PRD1. The mathematical model developed by Sim and Chrysikopoulos (Water Resour Res 36:173-179, 2000) that accounts for processes responsible for removal of viruses during vertical transport in one-dimensional, unsaturated porous media was used to fit the data collected from the laboratory experiments. The liquid to liquid-solid and liquid to air-liquid interface mass transfer rate coefficients were shown to increase for both bacteriophage as saturation levels were reduced. The experimental results indicate that even for unfavorable attachment conditions within a sand column (e.g., phosphate-buffered saline solution; pH = 7.5; ionic strength = 2 mM), saturation levels can affect virus transport through porous media. ?? Springer Science+Business Media B.V. 2008.

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal-Limbal and Human Conjunctival Epithelial Cells.

PubMed

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline; Barisani-Asenbauer, Talin

2017-06-01

To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal-limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT-based assay. The morphology of cells was also investigated. HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface.

Implications for Ophthalmic Formulations: Ocular Buffers Show Varied Cytotoxic Impact on Human Corneal–Limbal and Human Conjunctival Epithelial Cells

PubMed Central

Schuerer, Nadine; Stein, Elisabeth; Inic-Kanada, Aleksandra; Pucher, Marion; Hohenadl, Christine; Bintner, Nora; Ghasemian, Ehsan; Montanaro, Jacqueline

2017-01-01

Purpose: To investigate toxicity associated with buffers commonly used in topical ocular drug formulations using a human corneal–limbal epithelial (HCLE) and a human conjunctival epithelial (HCjE) cell model. Methods: HCLE and HCjE cells were incubated for 10, 30, or 60 minutes with 4 different buffers based on borate, citrate, phosphate, and Tris-HCl at 10, 50, and 100 mM concentrations. To detect possible delayed effects on cell viability, after 60 minutes of buffer incubation, cells were further incubated for 24 hours with a cell medium. Cell viability was determined using a colorimetric XTT–based assay. The morphology of cells was also investigated. Results: HCjE cells showed more sensitivity to buffer incubation than HCLE cells. The 100 mM phosphate buffer displayed significant delayed effects on cell viability of HCLE 16.8 ± 4.8% and HCjE 39.2 ± 6.1% cells after 60 minutes of exposure (P < 0.05). HCjE cell viability was reduced after 60 minutes incubations with 50 and 100 mM citrate buffer to 42.8 ± 6.5% and 39.3 ± 7.9%, respectively, and even lower percentages at the delayed time point (both P < 0.05). HCLE cell morphology was distinctly altered by 100 mM phosphate and Tris buffers after 30 minutes, whereas HCjE cells already showed marked changes after 10 minutes of exposure to 100 mM citrate and phosphate buffers. Conclusions: We observed a time-dependent decrease of viability in both HCLE and HCjE cells exposed to higher buffer concentrations. Therefore, we propose further in vivo studies to translate these finding to humans to discern the real effects of the buffer concentration in eye drops on the ocular surface. PMID:28399036

Stability of Colistin and Colistin Methanesulfonate in Aqueous Media and Plasma as Determined by High-Performance Liquid Chromatography

PubMed Central

Li, Jian; Milne, Robert W.; Nation, Roger L.; Turnidge, John D.; Coulthard, Kingsley

2003-01-01

The stabilities of colistin and colistin methanesulfonate (CMS) in different aqueous media were studied by specific high-performance liquid chromatography (HPLC) methods. Colistin was stable in water at 4 and 37°C for up to 60 days and 120 h, respectively. However, degradation was observed when colistin was stored in isotonic phosphate buffer (0.067 M, pH 7.4) and human plasma at 37°C. The stability of CMS from three different sources in water was explored by strong-anion-exchange (SAX) HPLC for CMS and by measuring the concentrations of colistin formed from the hydrolysis of CMS. The peaks of CMS in SAX HPLC disappeared almost completely after 12 h at 37°C, but appeared to remain intact for up to 2 days at 4°C. Over the same period, there was no formation of colistin at 4°C. In water, phosphate buffer, and plasma, there was rapid formation of colistin within 24 to 48 h at 37°C from the three sources of CMS. The hydrolysis products were assumed to be a complex mixture of many different sulfomethyl derivatives, including colistin. The stability of a fourth source of CMS in Mueller-Hinton broth examined during 30 min at 37°C revealed no formation of colistin. Along with previous microbiological studies, this suggested that different sulfomethyl CMSs possess intrinsic antibacterial activity. These results will be helpful for understanding the pharmacokinetics and pharmacodynamics of colistin and CMS in humans and animals. PMID:12654671

Optimization of a model of red blood cells for the study of anti-oxidant drugs, in terms of concentration of oxidant and phosphate buffer.

PubMed

Bureau, A; Lahet, J-J; Lenfant, F; Bouyer, F; Petitjean, M; Chaillot, B; Freysz, M

2005-08-01

The aggression of erythrocytes by an oxidative stress induces hemolysis. This paper aims to valid a model of erythrocytes in terms of composition of the phosphate buffer solution and of concentration of a well-known oxidant, AAPH. Three compositions of phosphate buffer solution are mixed with three concentrations of oxidant. The influence of these two parameters on hemolysis is independently studied by a variance analysis and a Kruskal-Wallis test when ANOVA is not available. The hemolysis rate increases with time at fixed oxidant concentration, but is not influenced by the composition of the buffer solution. The highest hemolysis rate, 90%, was only measured within 2 h with the highest oxidant concentration. If we retain this concentration of oxidant, the lower concentration of the buffer can by eliminated by a significant less hemolysis and the highest concentration of the buffer can by chosen in regard of the better precision for a similar hemolysis compared to the mean buffer. We hope to study the effect of anti-oxidant agent with such a model of erythrocytes.

Stability of the Stevia-Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure.

PubMed

Zhang, Jiewen; Bell, Leonard N

2017-04-01

Rebaudioside A is a natural noncaloric high-potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm 2 for dark conditions, 27 μW/cm 2 for low intensity, and 190 μW/cm 2 for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo-1st-order degradation rate constants increased significantly (P < 0.05) with increasing light intensity in all solutions. Under dark conditions, rebaudioside A in phosphate buffers was more susceptible to breakdown than in water and citrate buffers at both pH levels. However, exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light-protective packaging for beverages containing rebaudioside A will improve its stability. © 2017 Institute of Food Technologists®.

The use of physiological solutions or media in calcium phosphate synthesis and processing.

PubMed

Tas, A Cuneyt

2014-05-01

This review examined the literature to spot uses, if any, of physiological solutions/media for the in situ synthesis of calcium phosphates (CaP) under processing conditions (i.e. temperature, pH, concentration of inorganic ions present in media) mimicking those prevalent in the human hard tissue environments. There happens to be a variety of aqueous solutions or media developed for different purposes; sometimes they have been named as physiological saline, isotonic solution, cell culture solution, metastable CaP solution, supersaturated calcification solution, simulated body fluid or even dialysate solution (for dialysis patients). Most of the time such solutions were not used as the aqueous medium to perform the biomimetic synthesis of calcium phosphates, and their use was usually limited to the in vitro testing of synthetic biomaterials. This review illustrates that only a limited number of research studies used physiological solutions or media such as Earle's balanced salt solution, Bachra et al. solutions or Tris-buffered simulated body fluid solution containing 27mM HCO3(-) for synthesizing CaP, and these studies have consistently reported the formation of X-ray-amorphous CaP nanopowders instead of Ap-CaP or stoichiometric hydroxyapatite (HA, Ca10(PO4)6(OH)2) at 37°C and pH 7.4. By relying on the published articles, this review highlights the significance of the use of aqueous solutions containing 0.8-1.5 mMMg(2+), 22-27mM HCO3(-), 142-145mM Na(+), 5-5.8mM K(+), 103-133mM Cl(-), 1.8-3.75mM Ca(2+), and 0.8-1.67mM HPO4(2-), which essentially mimic the composition and the overall ionic strength of the human extracellular fluid (ECF), in forming the nanospheres of X-ray-amorphous CaP. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Mechanical, degradation and cytocompatibility properties of magnesium coated phosphate glass fibre reinforced polycaprolactone composites.

PubMed

Liu, Xiaoling; Hasan, Muhammad S; Grant, David M; Harper, Lee T; Parsons, Andrew J; Palmer, Graham; Rudd, Chris D; Ahmed, Ifty

2014-11-01

Retention of mechanical properties of phosphate glass fibre reinforced degradable polyesters such as polycaprolactone and polylactic acid in aqueous media has been shown to be strongly influenced by the integrity of the fibre/polymer interface. A previous study utilising 'single fibre' fragmentation tests found that coating with magnesium improved the fibre and matrix interfacial shear strength. Therefore, the aim of this study was to investigate the effects of a magnesium coating on the manufacture and characterisation of a random chopped fibre reinforced polycaprolactone composite. Short chopped strand non-woven phosphate glass fibre mats were sputter coated with degradable magnesium to manufacture phosphate glass fibre/polycaprolactone composites. The degradation behaviour (water uptake, mass loss and pH change of the media) of these polycaprolactone composites as well as of pure polycaprolactone was investigated in phosphate buffered saline. The Mg coated fibre reinforced composites revealed less water uptake and mass loss during degradation compared to the non-coated composites. The cations released were also explored and a lower ion release profile for all three cations investigated (namely Na(+), Mg(2+) and Ca(2+)) was seen for the Mg coated composite samples. An increase of 17% in tensile strength and 47% in tensile modulus was obtained for the Mg coated composite samples. Both flexural and tensile properties were investigated and a higher retention of mechanical properties was obtained for the Mg coated fibre reinforced composite samples up to 10 days immersion in PBS. Cytocompatibility study showed both composite samples (coated and non-coated) had good cytocompatibility with human osteosarcoma cell line. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Radiation survival of two nalidixic acid resistant strains of Salmonella typhimurium in various media

NASA Astrophysics Data System (ADS)

Shamsuzzaman, Kazi; Goodwin, Marlene; George, Ian; Singh, Harwant

Radiation doses required for 90% inactivation, the D10 values, have been determined for two nalidixic acid-resistant strains of Salmonella typhimurium, Nal R ATCC 13311 and K1-2B, in different media. The D10 values were 0.20, 0.57 and 0.53 kGy for the ATCC 13311 strain, and were 0.21, 0.4 and 0.32 kGy for the K1-2B strain, in phosphate buffer, in nutrient broth and on chicken drumsticks, respectively. Since these two strains have radiation sensitivity similar to several Salmonella serotypes reported in the literature, they are good indicator organisms for use in studies on the effect of irradiation on Salmonella in foods that might frequently be contaminated with such organisms.

Influence of calcium and phosphorus, lactose, and salt-to-moisture ratio on Cheddar cheese quality: pH buffering properties of cheese.

PubMed

Upreti, P; Bühlmann, P; Metzger, L E

2006-03-01

The pH buffering capacity of cheese is an important determinant of cheese pH. However, the effects of different constituents of cheese on its pH buffering capacity have not been fully clarified. The objective of this study was to characterize the chemical species and chemical equilibria that are responsible for the pH buffering properties of cheese. Eight cheeses with 2 levels of Ca and P (0.67 and 0.47% vs. 0.53 and 0.39%, respectively), residual lactose (2.4 vs. 0.78%), and salt-to-moisture ratio (6.4 vs. 4.8%) were manufactured. The pH-titration curves for these cheeses were obtained by titrating cheese:water (1:39 wt/wt) dispersions with 1 N HCl, and backtitrating with 1 N NaOH. To understand the role of different chemical equilibria and the respective chemical species in controlling the pH of cheese, pH buffering was modeled mathematically. The 36 chemical species that were found to be relevant for modeling can be classified as cations (Na+, Ca2+, Mg2+), anions (phosphate, citrate, lactate), protein-bound amino acids with a side-chain pKa in the range of 3 to 9 (glutamate, histidine, serine phosphate, aspartate), metal ion complexes (phosphate, citrate, and lactate complexes of Na+, Ca2+, and Mg2+), and calcium phosphate precipitates. A set of 36 corresponding equations was solved to give the concentrations of all chemical species as a function of pH, allowing the prediction of buffering curves. Changes in the calculated species concentrations allowed the identification of the chemical species and chemical equilibria that dominate the pH buffering properties of cheese in different pH ranges. The model indicates that pH buffering in the pH range from 4.5 to 5.5 is predominantly due to a precipitate of Ca and phosphate, and the protonation equilibrium involving the side chains of protein-bound glutamate. In the literature, the precipitate is often referred to as amorphous colloidal calcium phosphate. A comparison of experimental data and model predictions shows that the buffering properties of the precipitate can be explained, assuming that it consists of hydroxyapatite [Ca5(OH)(PO4)3] or Ca3(PO4)2. The pH buffering in the region from pH 3.5 to 4.5 is due to protonation of side-chain carboxylates of protein-bound glutamate, aspartate, and lactate, in order of decreasing significance. In addition, pH buffering between pH 5 to 8 in the backtitration results from the reprecipitation of calcium and phosphate either as CaHPO4 or Ca4H(PO4)3.

Delayed release film coating applications on oral solid dosage forms of proton pump inhibitors: case studies.

PubMed

Missaghi, Shahrzad; Young, Cara; Fegely, Kurt; Rajabi-Siahboomi, Ali R

2010-02-01

Formulation of proton pump inhibitors (PPIs) into oral solid dosage forms is challenging because the drug molecules are acid-labile. The aim of this study is to evaluate different formulation strategies (monolithic and multiparticulates) for three PPI drugs, that is, rabeprazole sodium, lansoprazole, and esomeprazole magnesium, using delayed release film coating applications. The core tablets of rabeprazole sodium were prepared using organic wet granulation method. Multiparticulates of lansoprazole and esomeprazole magnesium were prepared through drug layering of sugar spheres, using powder layering and suspension layering methods, respectively. Tablets and drug-layered multiparticulates were seal-coated, followed by delayed release film coating application, using Acryl-EZE(R), aqueous acrylic enteric system. Multiparticulates were then filled into capsules. The final dosage forms were evaluated for physical properties, as well as in vitro dissolution testing in both compendial acid phase, 0.1N HCl (pH 1.2), and intermediate pH, acetate buffer (pH 4.5), followed by phosphate buffer, pH 6.8. The stability of the delayed release dosage forms was evaluated upon storage in accelerated conditions [40 degrees C/75% relative humidity] for 3 months. All dosage forms demonstrated excellent enteric protection in the acid phase, followed by rapid release in their respective buffer media. Moreover, the delayed release dosage forms remained stable under accelerated stability conditions for 3 months. Results showed that Acryl-EZE enteric coating systems provide excellent performance in both media (0.1N HCl and acetate buffer pH 4.5) for monolithic and multiparticulate dosage forms.

A Chemist’s Perspective on the Role of Phosphorus at the Origins of Life

PubMed Central

Fernández-García, Christian; Coggins, Adam J.

2017-01-01

The central role that phosphates play in biological systems, suggests they also played an important role in the emergence of life on Earth. In recent years, numerous important advances have been made towards understanding the influence that phosphates may have had on prebiotic chemistry, and here, we highlight two important aspects of prebiotic phosphate chemistry. Firstly, we discuss prebiotic phosphorylation reactions; we specifically contrast aqueous electrophilic phosphorylation, and aqueous nucleophilic phosphorylation strategies, with dry-state phosphorylations that are mediated by dissociative phosphoryl-transfer. Secondly, we discuss the non-structural roles that phosphates can play in prebiotic chemistry. Here, we focus on the mechanisms by which phosphate has guided prebiotic reactivity through catalysis or buffering effects, to facilitating selective transformations in neutral water. Several prebiotic routes towards the synthesis of nucleotides, amino acids, and core metabolites, that have been facilitated or controlled by phosphate acting as a general acid–base catalyst, pH buffer, or a chemical buffer, are outlined. These facile and subtle mechanisms for incorporation and exploitation of phosphates to orchestrate selective, robust prebiotic chemistry, coupled with the central and universally conserved roles of phosphates in biochemistry, provide an increasingly clear message that understanding phosphate chemistry will be a key element in elucidating the origins of life on Earth. PMID:28703763

In vitro dissolution of proton-pump inhibitor products intended for paediatric and geriatric use in physiological bicarbonate buffer.

PubMed

Liu, Fang; Shokrollahi, Honaz

2015-05-15

Proton-pump inhibitor (PPI) products based on enteric coated multiparticulates are design to meet the needs of patients who cannot swallow tablets such as children and older adults. Enteric coated PPI preparations exhibit delays in in vivo absorption and onset of antisecretory effects, which is not reflected by the rapid in vitro dissolution in compendial pH 6.8 phosphate buffer commonly used for assessment of these products. A more representative and physiological medium, pH 6.8 mHanks bicarbonate buffer, was used in this study to evaluate the in vitro dissolution of enteric coated multiparticulate-based PPI products. Commercially available omeprazole, lansoprazole and esomeprazole products were subject to dissolution tests using USP-II apparatus in pH 4.5 phosphate buffer saline for 45 min (acid stage) followed by pH 6.8 phosphate buffer or pH 6.8 mHanks bicarbonate buffer. In pH 6.8 phosphate buffer, all nine tested products displayed rapid and comparable dissolution profiles meeting the pharmacopeia requirements for delayed release preparations. In pH 6.8 mHanks buffer, drug release was delayed and failed the pharmacopeia requirements from most enteric coated preparations. Despite that the same enteric polymer, methacrylic acid-ethyl acrylate copolymer (1:1), was applied to all commercial multiparticulate-based products, marked differences were observed between dissolution profiles of these preparations. The use of pH 6.8 physiological bicarbonate (mHanks) buffer can serve as a useful tool to provide realistic and discriminative in vitro release assessment of enteric coated PPI preparations and to assist rational formulation development of these products. Copyright © 2015 Elsevier B.V. All rights reserved.

The bioactivity of dietary anthocyanins is likely to be mediated by their degradation products.

PubMed

Kay, Colin D; Kroon, Paul A; Cassidy, Aedin

2009-05-01

To date the in vitro mechanistic bioactivity of anthocyanins has been exclusively explored using aglycones and glycoside conjugates, despite a lack of evidence establishing these as the biologically available forms. We conducted intestinal epithelial cell (Caco-2 cells) culture experiments, which indicated that after a 4 h incubation of anthocyanins in cell-free culture media (DMEM), 57% of the initial cyanidin-3-glucoside (C3G) and 96% of cyanidin had degraded. The level of degradation was not statistically different from that of cultured cell incubations, suggesting that degradation was spontaneous. Degradation products were identified as protocatechuic acid (PCA) and phloroglucinaldehyde (PGA), and were confirmed in two other buffer matrices (phosphate and Hank's buffers). In cultured cell media the degradation products PCA and PGA were metabolised to glucuronide and sulphate conjugates, as indicated by both enzyme hydrolysis (sulphatase and glucuronidase treatments) and MS (PCA and PGA m/z = 155; sulphate = 235; glucuronide = 331). These data suggest a significant proportion of intestinal metabolites of anthocyanins are likely to be conjugates of their degradation products. Future efforts to establish the biological activities of anthocyanins should therefore include the investigation of phenolic acid and aldehyde products of degradation, along with their respective metabolites.

Stability of polymer encapsulated quantum dots in cell culture media

NASA Astrophysics Data System (ADS)

Ojea-Jiménez, I.; Piella, J.; Nguyen, T.-L.; Bestetti, A.; Ryan, A. D.; Puntes, V.

2013-04-01

The unique optical properties of Quantum Dots have attracted a great interest to use these nanomaterials in diverse biological applications. The synthesis of QDs by methods from the literature permits one to obtain nanocrystals coated by hydrophobic alkyl coordinating ligands and soluble in most of the cases in organic solvents. The ideal biocompatible QD must be homogeneously dispersed and colloidally stable in aqueous solvents, exhibit pH and salt stability, show low levels of nonspecific binding to biological components, maintain a high quantum yield, and have a small hydrodynamic diameter. Polymer encapsulation represents an excellent scaffold on which to build additional biological function, allowing for a wide range of grafting approaches for biological ligands. As these QD are functionalized with poly(ethylene)glycol (PEG) derivatives on their surface, they show long term stability without any significant change in the optical properties, and they are also highly stable in the most common buffer solutions such as Phosphate Buffer Saline (PBS) or borate. However, as biological studies are normally done in more complex biological media which contain a mixture of amino acids, salts, glucose and vitamins, it is essential to determine the stability of our synthesized QDs under these conditions before tackling biological studies.

TRIS buffer in simulated body fluid distorts the assessment of glass-ceramic scaffold bioactivity.

PubMed

Rohanová, Dana; Boccaccini, Aldo Roberto; Yunos, Darmawati Mohamad; Horkavcová, Diana; Březovská, Iva; Helebrant, Aleš

2011-06-01

The paper deals with the characterisation of the bioactive phenomena of glass-ceramic scaffold derived from Bioglass® (containing 77 wt.% of crystalline phases Na(2)O·2CaO·3SiO(2) and CaO·SiO(2) and 23 wt.% of residual glass phase) using simulated body fluid (SBF) buffered with tris-(hydroxymethyl) aminomethane (TRIS). A significant effect of the TRIS buffer on glass-ceramic scaffold dissolution in SBF was detected. To better understand the influence of the buffer, the glass-ceramic scaffold was exposed to a series of in vitro tests using different media as follows: (i) a fresh liquid flow of SBF containing tris (hydroxymethyl) aminomethane; (ii) SBF solution without TRIS buffer; (iii) TRIS buffer alone; and (iv) demineralised water. The in vitro tests were provided under static and dynamic arrangements. SBF buffered with TRIS dissolved both the crystalline and residual glass phases of the scaffold and a crystalline form of hydroxyapatite (HAp) developed on the scaffold surface. In contrast, when TRIS buffer was not present in the solutions only the residual glassy phase dissolved and an amorphous calcium phosphate (Ca-P) phase formed on the scaffold surface. It was confirmed that the TRIS buffer primarily dissolved the crystalline phase of the glass-ceramic, doubled the dissolving rate of the scaffold and moreover supported the formation of crystalline HAp. This significant effect of the buffer TRIS on bioactive glass-ceramic scaffold degradation in SBF has not been demonstrated previously and should be considered when analysing the results of SBF immersion bioactivity tests of such systems. Copyright © 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Immobilization of microorganisms for detection by solid-phase immunoassays.

PubMed Central

Ibrahim, G F; Lyons, M J; Walker, R A; Fleet, G H

1985-01-01

Several cultures of gram-negative and gram-positive bacteria were successfully immobilized with titanous hydroxide. The immobilization efficiency for the microorganisms investigated in saline and broth media ranged from 80.2 to 99.9%. The immobilization of salmonellae was effective over a wide pH range. The presence of buffers, particularly phosphate buffer, drastically reduced the immobilization rate. However, buffers may be added to immunoassay systems after immobilization of microorganisms. The immobilization process involved only one step, i.e., shaking 100 microliter of culture with 50 microliter of titanous hydroxide suspension in polystyrene tubes for only 10 min. The immobilized cells were so tenaciously bound that vigorous agitation for 24 h did not result in cell dissociation. The nonspecific binding of 125I-labeled antibody from rabbits and 125I-labeled protein A by titanous hydroxide was inhibited in the presence of 2% gelatin and amounted to only 5.6 and 3.9%, respectively. We conclude that this immobilization procedure is a potentially powerful tool which could be utilized in solid-phase immunoassays concerned with the diagnosis of microorganisms. PMID:3900128

Quantification of the aggregation of magnetic nanoparticles with different polymeric coatings in cell culture medium

NASA Astrophysics Data System (ADS)

Eberbeck, D.; Kettering, M.; Bergemann, C.; Zirpel, P.; Hilger, I.; Trahms, L.

2010-10-01

The knowledge of the physico-chemical characteristics of magnetic nanoparticles (MNPs) is essential to enhance the efficacy of MNP-based therapeutic treatments (e.g. magnetic heating, magnetic drug targeting). According to the literature, the MNP uptake by cells may depend on the coating of MNPs, the surrounding medium as well as on the aggregation behaviour of the MNPs. Therefore, in this study, the aggregation behaviour of MNPs in various media was investigated. MNPs with different coatings were suspended in cell culture medium (CCM) containing fetal calf serum (FCS) and the distribution of the hydrodynamic sizes was measured by magnetorelaxometry (MRX). FCS as well as bovine serum albumin (BSA) buffer (phosphate buffered saline with 0.1% bovine serum albumin) may induce MNP aggregation. Its strength depends crucially on the type of coating. The degree of aggregation in CCM depends on its FCS content showing a clear, local maximum at FCS concentrations, where the IgG concentration (part of FCS) is of the order of the MNP number concentration. Thus, we attribute the observed aggregation behaviour to the mechanism of agglutination of MNPs by serum compartments as for example IgG. No aggregation was induced for MNPs coated with dextran, polyarabic acid or sodium phosphate, respectively, which were colloidally stable in CCM.

Biomimetic Silica Nanoparticles Prepared by a Combination of Solid-Phase Imprinting and Ostwald Ripening.

PubMed

Piletska, Elena; Yawer, Heersh; Canfarotta, Francesco; Moczko, Ewa; Smolinska-Kempisty, Katarzyna; Piletsky, Stanislav S; Guerreiro, Antonio; Whitcombe, Michael J; Piletsky, Sergey A

2017-09-14

Herein we describe the preparation of molecularly imprinted silica nanoparticles by Ostwald ripening in the presence of molecular templates immobilised on glass beads (the solid-phase). To achieve this, a seed material (12 nm diameter silica nanoparticles) was incubated in phosphate buffer in the presence of the solid-phase. Phosphate ions act as a catalyst in the ripening process which is driven by differences in surface energy between particles of different size, leading to the preferential growth of larger particles. Material deposited in the vicinity of template molecules results in the formation of sol-gel molecular imprints after around 2 hours. Selective washing and elution allows the higher affinity nanoparticles to be isolated. Unlike other strategies commonly used to prepare imprinted silica nanoparticles this approach is extremely simple in nature and can be performed under physiological conditions, making it suitable for imprinting whole proteins and other biomacromolecules in their native conformations. We have demonstrated the generic nature of this method by preparing imprinted silica nanoparticles against targets of varying molecular mass (melamine, vancomycin and trypsin). Binding to the imprinted particles was demonstrated in an immunoassay (ELISA) format in buffer and complex media (milk or blood plasma) with sub-nM detection ability.

Thermoresponsive, in situ crosslinkable hydrogels based on N-isopropylacrylamide: Fabrication, characterization and mesenchymal stem cell encapsulation

PubMed Central

Klouda, Leda; Perkins, Kevin R.; Watson, Brendan M.; Hacker, Michael C.; Bryant, Stephanie J.; Raphael, Robert M.; Kasper, F. Kurtis; Mikos, Antonios G.

2011-01-01

Hydrogels that solidify in response to a dual, physical and chemical, mechanism upon temperature increase were fabricated and characterized. The hydrogels were based on N-isopropylacrylamide, which renders them thermoresponsive, and contained covalently crosslinkable moieties in the macromers. The effects of the macromer end group, namely acrylate or methacrylate, and the fabrication conditions were investigated on the degradative and swelling properties of the hydrogels. The hydrogels exhibited higher swelling below their lower critical solution temperature (LCST). When immersed in cell culture media at physiological temperature, which was above their LCST, hydrogels showed constant swelling and no degradation over eight weeks, with methacrylated hydrogels having higher swelling than their acrylated analogs. In addition, hydrogels immersed in cell culture media under the same conditions showed lower swelling as compared to phosphate buffered saline. The interplay between chemical crosslinking and thermally induced phase separation affected the swelling characteristics of hydrogels in different media. Mesenchymal stem cells encapsulated in the hydrogels in vitro were viable over three weeks and markers of osteogenic differentiation were detected when the cells were cultured with osteogenic supplements. Hydrogel mineralization in the absence of cells was observed in cell culture medium with the addition of fetal bovine serum and β-glycerol phosphate. The results suggest that these hydrogels may be suitable as carriers for cell delivery in tissue engineering. PMID:21187170

Diluents for stabilization of tuberculin

PubMed Central

Magnusson, Mogens; Guld, Johannes; Magnus, Knut; Waaler, Hans

1958-01-01

Tuberculin is known to be adsorbed to containers and syringes. In the present paper, the adsorption which takes place in the ampoules has been studied in relation to the diluent for the tuberculin. Adsorption was most evident in dilutions prepared with saline or with phosphate buffer containing dextran. The inclusion in phosphate buffer diluent of small amounts of proteins or synthetic surface-active agents decreased or prevented adsorption. A boric-acid sodium-borate diluent containing gum arabic, previously recommended for the preparation of stabilized tuberculin dilutions, was found to be ineffective. The most suitable diluent for the preparation of stable tuberculin dilutions was a 0.05‰ solution of Tween 80 in phosphate-buffered saline; this diluent appeared to prevent adsorption under a variety of experimental conditions. The inclusion of Tween 80 in the diluent had little or no effect on the general storage stability of purified tuberculin. Sensitization experiments in guinea-pigs, rabbits and humans showed that no sensitization against Tween 80 need be feared when a 0.05‰ solution of Tween 80 in phosphate buffered saline is used in the preparation of tuberculin dilutions. PMID:13618720

Histological preparation of developing vestibular otoconia for scanning electron microscopy

NASA Technical Reports Server (NTRS)

Huss, D.; Dickman, J. D.

2003-01-01

The unique nature of vestibular otoconia as calcium carbonate biominerals makes them particularly susceptible to chemical deformation during histological processing. We fixed and stored otoconia from all three otolith endorgans of embryonic, hatchling and adult Japanese quail in glutaraldehyde containing either phosphate or non-phosphate buffers for varying lengths of time and processed them for scanning electron microscopy. Otoconia from all age groups and otolith endorgans processed in 0.1 M phosphate buffer (pH 7.4) showed abnormal surface morphology when compared to acetone fixed controls. Otoconia processed in 0.1 M sodium cacodylate or HEPES buffered artificial endolymph (pH 7.4) showed normal morphology that was similar to controls. The degree of otoconial deformation was directly related to the time exposed to phosphate buffer. Short duration exposure produced particulate deformations while longer exposures resulted in fused otoconia that formed solid sheets. Otoconial surface deformation and fusing was independent of the glutaraldehyde component of the histological processing. These findings should help vestibular researchers to develop appropriate histological processing protocols in future studies of otoconia.

Determination of total arsenic and arsenic(III) in phosphate fertilizers by hydride generation atomic absorption spectrometry after ultrasound-assisted extraction based on a control acid media.

PubMed

Rezende, Helen Cristine; Coelho, Nivia Maria Melo

2014-01-01

An ultrasound-assisted extraction procedure was developed for determination of inorganic arsenic (As) in phosphate fertilizer by hydride generation atomic absorption spectrometry. The variables that affect the hydride generation step were optimized, including the reducer, acid, sample flow rate, and concentrations of the acid and reducer. The determination of As(lll) was performed through the simple control of solution pH with a 0.5 M citric acid-sodium citrate buffer solution at pH 4.5, and total As was determined after a pre-reduction reaction with 1.0% (w/v) thiourea. Ultrasound-assisted acid extraction was performed, and the parameters sonication time and acid and Triton X-114 concentrations were optimized using a 23 factorial design and central composite design. LODs for As(lll) and total As were 0.029 and 0.022 microg/L, respectively. The accuracy of the method was confirmed with certified reference materials. The method was successfully applied in the determination of inorganic As in phosphate fertilizer samples.

Electromechanical and Elastic Probing of Bacteria in Cell Culture Medium

PubMed Central

Thompson, G.L.; Reukov, V.V.; Nikiforov, M.P.; Jesse, S.; Kalinin, S.V.; Vertegel, A.A.

2012-01-01

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of different types of bacteria in pure water. Here, the BEPFM method is performed for the first time in physiologically-relevant electrolyte media, such as Dulbecco’s phosphate-buffered saline (DPBS) and Dulbecco’s modified Eagle’s medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria are demonstrated in DPBS. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media. PMID:22641388

Electromechanical and elastic probing of bacteria in a cell culture medium

NASA Astrophysics Data System (ADS)

Thompson, G. L.; Reukov, V. V.; Nikiforov, M. P.; Jesse, S.; Kalinin, S. V.; Vertegel, A. A.

2012-06-01

Rapid phenotype characterization and identification of cultured cells, which is needed for progress in tissue engineering and drug testing, requires an experimental technique that measures physical properties of cells with sub-micron resolution. Recently, band excitation piezoresponse force microscopy (BEPFM) has been proven useful for recognition and imaging of bacteria of different types in pure water. Here, the BEPFM method is performed for the first time on physiologically relevant electrolyte media, such as Dulbecco’s phosphate-buffered saline (DPBS) and Dulbecco’s modified Eagle’s medium (DMEM). Distinct electromechanical responses for Micrococcus lysodeikticus (Gram-positive) and Pseudomonas fluorescens (Gram-negative) bacteria in DPBS are demonstrated. The results suggest that mechanical properties of the outer surface coating each bacterium, as well as the electrical double layer around them, are responsible for the BEPFM image formation mechanism in electrolyte media.

Viability of BCG suspensions, freshly prepared, stored, and light-exposed, estimated in different ways.

PubMed

CHRISTENSEN, P A; ROBINSON, M; WIDDICOMBE, M

1955-01-01

Tested by the roll-tube method, the inclusion in Dubos medium of oleic acid, Tween 80, or glucose hastens colony growth of tubercle bacilli (BCG), but the variability in counts between replicate bottles is large, and the mean count is low compared with that obtained in media free of these substances.The addition of glycerol hastens the development of colonies, and counts on glycerol medium may differ from those on glycerol-free medium. BCG suspensions stored at about 23 degrees C or exposed to skyshine or sunlight become glycerol-sensitive. Results obtained with glycerol medium may not, therefore, always be acceptable.The preparation and use in the roll-tube method of a simple medium is described. This consists of horse serum, M/15 phosphate buffer, and agar, and is preferable to more complex media as it tends to give higher viable counts and is easier to store and prepare.Stored at about 23 degrees C, the viability of BCG is better preserved in neutral phosphate buffer than in suspending fluids containing Sauton medium; no such difference is noticed with cold storage.Glutamic acid added in a concentration of 0.35% is without effect on the viability of suspensions stored in the cold, but under certain conditions it may have some preserving value at higher storage temperatures.Exposure to daylight in the laboratory, even for several hours, does not kill BCG or render it glycerol-sensitive. Exposure to intense skyshine does kill, but the mortality observed at the South African Institute for Medical Research is low compared with that recorded elsewhere. Possible explanations of this discrepancy are discussed.

Viability of BCG suspensions, freshly prepared, stored, and light-exposed, estimated in different ways

PubMed Central

Christensen, P. Agerholm; Robinson, Mary; Widdicombe, Margaret

1955-01-01

Tested by the roll-tube method, the inclusion in Dubos medium of oleic acid, Tween 80, or glucose hastens colony growth of tubercle bacilli (BCG), but the variability in counts between replicate bottles is large, and the mean count is low compared with that obtained in media free of these substances. The addition of glycerol hastens the development of colonies, and counts on glycerol medium may differ from those on glycerol-free medium. BCG suspensions stored at about 23°C or exposed to skyshine or sunlight become glycerol-sensitive. Results obtained with glycerol medium may not, therefore, always be acceptable. The preparation and use in the roll-tube method of a simple medium is described. This consists of horse serum, M/15 phosphate buffer, and agar, and is preferable to more complex media as it tends to give higher viable counts and is easier to store and prepare. Stored at about 23°C, the viability of BCG is better preserved in neutral phosphate buffer than in suspending fluids containing Sauton medium; no such difference is noticed with cold storage. Glutamic acid added in a concentration of 0.35% is without effect on the viability of suspensions stored in the cold, but under certain conditions it may have some preserving value at higher storage temperatures. Exposure to daylight in the laboratory, even for several hours, does not kill BCG or render it glycerol-sensitive. Exposure to intense skyshine does kill, but the mortality observed at the South African Institute for Medical Research is low compared with that recorded elsewhere. Possible explanations of this discrepancy are discussed. PMID:14379008

Final report of the key comparison APMP.QM-K9: APMP comparison on pH measurement of phosphate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Ohata, Masaki; Cherdchu, Chainarong; Tangpaisarnkul, Nongluck

2011-01-01

The APMP.QM-K9 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phosphate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan, NMIJ, and the National Institute of Metrology of Thailand, NIMT, in August 2009. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K9, CCQM-K9.1 and CCQM-K9.2. The comparison material was a phosphate buffer of pH around 6.86 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the first APMP key comparison on pH measurement and the third APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004 and APMP.QM-P09 (a phthalate buffer) in 2006. The results can be used further by any participant to support its CMC claim for a phosphate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the temperature(s) used or the full temperature range between 15 °C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Ex vivo evaluation of various instrumentation techniques and irrigants in reducing E. faecalis within root canals.

PubMed

Basmaci, F; Oztan, M D; Kiyan, M

2013-09-01

To evaluate ex vivo the effectiveness of single-file instrumentation techniques compared with serial Ni-Ti rotary instrumentation with several irrigation regimens in reducing E. faecalis within root canals. A total of 81 extracted human mandibular premolar teeth with a single root canal were infected with E. faecalis before and after canal preparation. Samples were divided randomly into 9 groups, as follows: group 1-A: sterile phosphate-buffered saline + Self-adjusting file, group 1-B: 5% sodium hypochlorite + 15% EDTA + Self-adjusting file, group 1-C: 5% sodium hypochlorite + 7% maleic acid + Self-adjusting file, group 2-A: sterile phosphate-buffered saline + Reciproc (R25), group 2-B: 5% sodium hypochlorite + 15% EDTA + Reciproc (R25), group 2-C: 5% sodium hypochlorite + 7% maleic acid + Reciproc (R25), group 3-A: sterile phosphate-buffered saline + ProTaper, group 3-B: 5% sodium hypochlorite + 15% EDTA + ProTaper, group 3-C: 5% sodium hypochlorite + 7% maleic acid + ProTaper. anova was used to analyse statistically the differences in terms of reduction in colony counts between the groups, and Dunn's post hoc test was used for multiple comparisons. All techniques and irrigation regimens significantly reduced the number of bacterial cells in the root canal (P < 0.001). Comparisons amongst the groups revealed significant differences between group 1A (sterile phosphate-buffered saline + Self-adjusting file)/group 1B (5% sodium hypochlorite + 15% EDTA + Self-adjusting file) (P = 0.031), group 1A (sterile phosphate-buffered saline + Self-adjusting file)/group 2C (5% sodium hypochlorite + 7% maleic acid + Reciproc) (P = 0.003), group 2A (sterile phosphate-buffered saline + Reciproc)/group 3B (5% sodium hypochlorite + 15% EDTA + ProTaper) (P = 0.036), group 3B (5% sodium hypochlorite + 15% EDTA + ProTaper)/group 1A (sterile phosphate-buffered saline + Self-adjusting file) (P < 0.001), and group 3C (5% sodium hypochlorite + 7% maleic acid + ProTaper)/group 1A (sterile phosphate-buffered saline + Self-adjusting file) (P = 0.033). No significant differences in terms of reduction in microbial counts were observed between single-file techniques (SAF and Reciproc) and serial Ni-Ti instrumentation technique (ProTaper) in combination with irrigants. © 2013 International Endodontic Journal. Published by John Wiley & Sons Ltd.

In silico prediction of drug dissolution and absorption with variation in intestinal pH for BCS class II weak acid drugs: ibuprofen and ketoprofen.

PubMed

Tsume, Yasuhiro; Langguth, Peter; Garcia-Arieta, Alfredo; Amidon, Gordon L

2012-10-01

The FDA Biopharmaceutical Classification System guidance allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms only for BCS class I. Extensions of the in vivo biowaiver for a number of drugs in BCS class III and BCS class II have been proposed, in particular, BCS class II weak acids. However, a discrepancy between the in vivo BE results and in vitro dissolution results for BCS class II acids was recently observed. The objectives of this study were to determine the oral absorption of BCS class II weak acids via simulation software and to determine if the in vitro dissolution test with various dissolution media could be sufficient for in vitro bioequivalence studies of ibuprofen and ketoprofen as models of carboxylic acid drugs. The oral absorption of these BCS class II acids from the gastrointestinal tract was predicted by GastroPlus™. Ibuprofen did not satisfy the bioequivalence criteria at lower settings of intestinal pH of 6.0. Further the experimental dissolution of ibuprofen tablets in a low concentration phosphate buffer at pH 6.0 (the average buffer capacity 2.2 mmol l (-1) /pH) was dramatically reduced compared with the dissolution in SIF (the average buffer capacity 12.6 mmol l (-1) /pH). Thus these predictions for the oral absorption of BCS class II acids indicate that the absorption patterns depend largely on the intestinal pH and buffer strength and must be considered carefully for a bioequivalence test. Simulation software may be a very useful tool to aid the selection of dissolution media that may be useful in setting an in vitro bioequivalence dissolution standard. Copyright © 2012 John Wiley & Sons, Ltd.

In Silico Prediction of Drug Dissolution and Absorption with variation in Intestinal pH for BCS Class II Weak Acid Drugs: Ibuprofen and Ketoprofen§

PubMed Central

Tsume, Yasuhiro; Langguth, Peter; Garcia-Arieta, Alfredo; Amidon, Gordon L.

2012-01-01

The FDA Biopharmaceutical Classification System guidance allows waivers for in vivo bioavailability and bioequivalence studies for immediate-release solid oral dosage forms only for BCS class I. Extensions of the in vivo biowaiver for a number of drugs in BCS Class III and BCS class II have been proposed, particularly, BCS class II weak acids. However, a discrepancy between the in vivo- BE results and in vitro- dissolution results for a BCS class II acids was recently observed. The objectives of this study were to determine the oral absorption of BCS class II weak acids via simulation software and to determine if the in vitro dissolution test with various dissolution media could be sufficient for in vitro bioequivalence studies of ibuprofen and ketoprofen as models of carboxylic acid drugs. The oral absorption of these BCS class II acids from the gastrointestinal tract was predicted by GastroPlus™. Ibuprofen did not satisfy the bioequivalence criteria at lower settings of intestinal pH=6.0. Further the experimental dissolution of ibuprofen tablets in the low concentration phosphate buffer at pH 6.0 (the average buffer capacity 2.2 mmol L-1/pH) was dramatically reduced compared to the dissolution in SIF (the average buffer capacity 12.6 mmol L -1/pH). Thus these predictions for oral absorption of BCS class II acids indicate that the absorption patterns largely depend on the intestinal pH and buffer strength and must be carefully considered for a bioequivalence test. Simulation software may be very useful tool to aid the selection of dissolution media that may be useful in setting an in vitro bioequivalence dissolution standard. PMID:22815122

Laser Raman spectra of mono-, oligo- and polysaccharides in solution

NASA Astrophysics Data System (ADS)

Barrett, T. W.

We examined the Raman spectra of thirteen sugars—seven monosaccharides, two disaccharides, one trisaccharide and three polysaccharides—in the wavelength range 200—1700 cm -1 and (i) varied the phosphate buffered solution from pH 6.0 to 8.5 at constant ionic strength of 0.1 and (ii) varied HCl solutions from pH 0.8 to 5.0. As is to be expected with molecules containing COH groupings, all the molecular spectra are distinct. Of the thirteen sugars examined, only D-fructose 1,6-diphosphate (FDP) demonstrated spectral changes for the pH range 6.0—8.5 in phosphate buffer; but all exhibited band intensity enhancement in HCl at the lower pHs, but not band wavenumber changes. The results indicate that: (i) changes in the pH of the major intracellular buffer, phosphate, toward acidity, are able to hydrolyze the 1-phosphate group of FDP and the relative concentration of fructose 1-phosphate to fructose 6-phosphate is indicated by the intensity ratio of the 982 and 1080 cm -1 bands; (ii) it appears that all phosphate groups of FDP are hydrolyzed at pH 0.8 in HCl; and (iii) although conditions of extreme acidity are able to hydrolyze other sugars examined, there is no major degradation.

Controlled release of acidic drugs in compendial and physiological hydrogen carbonate buffer from polymer blend-coated oral solid dosage forms.

PubMed

Wulff, R; Rappen, G-M; Koziolek, M; Garbacz, G; Leopold, C S

2015-09-18

The objective of this study was to investigate the suitability of "Eudragit® RL/Eudragit® L55" (RL/L55) blend coatings for a pH-independent release of acidic drugs. A coating for ketoprofen and naproxen mini tablets was developed showing constant drug release rate under pharmacopeial two-stage test conditions for at least 300 min. To simulate drug release from the mini tablets coated with RL/L55 blends in the gastrointestinal (GI) tract, drug release profiles in Hanks buffer pH 6.8 were recorded and compared with drug release profiles in compendial media. RL/L55 blend coatings showed increased drug permeability in Hanks buffer pH 6.8 compared to phosphate buffer pH 6.8 due to its higher ion concentration. However, drug release rates of acidic drugs were lower in Hanks buffer pH 6.8 because of the lower buffer capacity resulting in reduced drug solubility. Further dissolution tests were performed in Hanks buffer using pH sequences simulating the physiological pH conditions in the GI tract. Drug release from mini tablets coated with an RL/L55 blend (8:1) was insensitive to pH changes of the medium within the pH range of 5.8-7.5. It was concluded that coatings of RL/L55 blends show a high potential for application in coated oral drug delivery systems with a special focus on pH-independent release of acidic drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

Structure-Function Relationship of Hydrophiidae Postsynaptic Neurotoxins

DTIC Science & Technology

1990-09-18

24 hr. Buffer F consisted of 10 mM sodium phosphate, pH 7.5. containing 0.02% (w/v) lauryl sulfate (SDS), and 0.04% (w/v) sodium cholate. The...subjected to gel filtration on Sephadex G-50-50 using 10 mM sodium phosphate buffer (pH 6.5) containing 0.1 M NaCl. Samples were dissolved in 3.5 ml buffer...sequencing. Isolation of Cobrotoxin. The venom from NaJa naia atra was subjected to Sephadex G50-50 gel filtration pre-equilibrated with 10 mM sodium

A segmental chronic pain syndrome in rats associated with intrathecal infusion of NMDA: evidence for selective action in the dorsal horn.

PubMed

Zochodne, D W; Murray, M; Nag, S; Riopelle, R J

1994-02-01

We explored the effects of chronic lumbar intrathecal NMDA infusion (mini-osmotic pumps) in Sprague-Dawley rats on motor and sensory axon integrity. Several different infusion protocols, each given over a 4 week period were examined: 0.15 M NMDA in phosphate buffered saline; phosphate buffered saline without NMDA; and 0.20 M magnesium sulfate plus 0.15 M NMDA; 0.35 M NMDA. In two additional protocols, 0.15 M NMDA or phosphate buffered saline were infused for a total of 8 weeks. Within 1-2 weeks of the onset of NMDA, but not phosphate buffered saline infusions, the rats exhibited irritability, circling, biting and excessive grooming resulting in loss of hair, and skin ulcerations from autotomy localized to lumbar and sacral innervated dermatomes. Co-infusion of NMDA with magnesium sulfate almost completely prevented these findings. The behavioural changes were not associated with abnormalities of sensory or motor conduction. Intrathecal infusion of NMDA induces a chronic "central" experimental pain disorder in rats, localized to the cord segment with the greatest exposure to the infusion, without involvement of peripheral sensory axons and sparing the axonal integrity of anterior horn cells.

Silica nanoparticle stability in biological media revisited.

PubMed

Yang, Seon-Ah; Choi, Sungmoon; Jeon, Seon Mi; Yu, Junhua

2018-01-09

The stability of silica nanostructure in the core-silica shell nanomaterials is critical to understanding the activity of these nanomaterials since the exposure of core materials due to the poor stability of silica may cause misinterpretation of experiments, but unfortunately reports on the stability of silica have been inconsistent. Here, we show that luminescent silver nanodots (AgNDs) can be used to monitor the stability of silica nanostructures. Though relatively stable in water and phosphate buffered saline, silica nanoparticles are eroded by biological media, leading to the exposure of AgNDs from AgND@SiO 2 nanoparticles and the quenching of nanodot luminescence. Our results reveal that a synergistic effect of organic compounds, particularly the amino groups, accelerates the erosion. Our work indicates that silica nanostructures are vulnerable to cellular medium and it may be possible to tune the release of drug molecules from silica-based drug delivery vehicles through controlled erosion.

Confocal raman microscopy as a non-invasive tool to investigate the phase composition of frozen complex cryopreservation media.

PubMed

Kreiner-Møller, A; Stracke, F; Zimmermann, H

2013-01-01

Various cryoprotective agents (CPA) are added to cell media in order to avoid cell injury during cryo preservation. The resulting complex environment of the preserved cell, consisting of crystalline and liquid phases can however not be investigated non-invasively by established methods in cryobiology. This study shows how scanning confocal Raman microscopy can non-invasively extract information on chemical composition, phase domain and distribution at cryogenic temperatures. The formation of the salt hydrate, hydrohalite NaCl∙H2O, in solutions comprised of phosphate buffered saline (PBS) and dimethyl sulphoxide (DMSO) is studied in particular. Scanning confocal Raman microscopy can be used to unambiguously identify hydrohalite in a medium containing DMSO and saline. The confocal Raman microscopy imaging along with differential scanning calorimetric measurements further show that the hydrohalite is formed without eutectic formation. This method also allows for discrimination between closely packed hydrohalite crystals that are oriented differently.

Effect of curcumin on the binding of cationic, anionic and nonionic surfactants with myoglobin

NASA Astrophysics Data System (ADS)

Mondal, Satyajit; Ghosh, Soumen

2017-04-01

Interaction of a globular protein, myoglobin and different surfactants has been studied in the absence and presence of curcumin in phosphate buffer at pH = 7.4 by UV-VIS spectrophotometry, fluorimetry and fluorescence polarization anisotropy methods. Results show that heme environment of myoglobin is changed by cationic cetyltrimethylammonium bromide (CTAB) and sodium N-dodecanoyl sarcosinate (SDDS). In the presence of curcumin, CTAB cannot change the heme; but SDDS can make change. Nonionic surfactant N-decanoyl-N-methylglucamine (Mega 10) cannot change the heme environment. Protein is unfolded by the surfactant. Curcumin can prevent the unfolding of protein in the low concentration region of ionic surfactants such as CTAB and SDDS. In nonionic surfactant media, curcumin accelerates the denaturation process. Due to myoglobin-curcumin complex formation, rotational motion of curcumin decreases in surfactant media and so anisotropy increases.

Effect of pH and the role of organic matter in the adsorption of isoproturon on soils.

PubMed

Ertli, Tímea; Marton, Aurél; Földényi, Rita

2004-11-01

Equilibrium measurements were carried out with the herbicide isoproturon on natural adsorbents (brown forest-, chernozem-, sandy soils and quartz) in different buffered media (pH 5, 7, 8 phosphate buffer). Adsorption isotherms were fitted by a multi-step adsorption equation providing numerical information used in the environmental propagation models and risk assessment works. In the adsorption of the slightly polar isoproturon the dissolved organic matter of the soil and the pH play an important role. At molecular level, results are interpreted by taking into consideration the hydrophobic interaction and the formation of hydrogen bonds between the surface and the solute. The observed adsorption behavior indicates that the organic matter content of the soils and its soluble fulvic acid, alkaline soluble humic acid and insoluble humin fractions were considerable different. The chernozem soil containing the highest amount of insoluble organic fraction proved to be a very efficient adsorbent. The brown forest and the sandy soils exhibit rather similar adsorbent properties but at pH 7 the latter containing more fulvic acid adsorbs less isoproturon due to the enhanced solubility of the soil organic matter. In alkaline conditions the negatively charged solute and the surface repel each other and the hydrophobic interactions are also weaker than in neutral media.

Thermal stability of tagatose in solution.

PubMed

Luecke, Katherine J; Bell, Leonard N

2010-05-01

Tagatose, a monosaccharide similar to fructose, has been shown to behave as a prebiotic. To deliver this prebiotic benefit, tagatose must not degrade during the processing of foods and beverages. The objective of this study was to evaluate the thermal stability of tagatose in solutions. Tagatose solutions were prepared in 0.02 and 0.1 M phosphate and citrate buffers at pHs 3 and 7, which were then held at 60, 70, and 80 degrees C. Pseudo-1st-order rate constants for tagatose degradation were determined. In citrate and phosphate buffers at pH 3, minimal tagatose was lost and slight browning was observed. At pH 7, tagatose degradation rates were enhanced. Degradation was faster in phosphate buffer than citrate buffer. Higher buffer concentrations also increased the degradation rate constants. Enhanced browning accompanied tagatose degradation in all buffer solutions at pH 7. Using the activation energies for tagatose degradation, less than 0.5% and 0.02% tagatose would be lost under basic vat and HTST pasteurization conditions, respectively. Although tagatose does breakdown at elevated temperatures, the amount of tagatose lost during typical thermal processing conditions would be virtually negligible. Practical Application: Tagatose degradation occurs minimally during pasteurization, which may allow for its incorporation into beverages as a prebiotic.

In silico and in vitro prediction of gastrointestinal absorption from potential drug eremantholide C.

PubMed

Caldeira, Tamires G; Saúde-Guimarães, Dênia A; Dezani, André B; Serra, Cristina Helena Dos Reis; de Souza, Jacqueline

2017-11-01

Analysis of the biopharmaceutical properties of eremantholide C, sesquiterpene lactone with proven pharmacological activity and low toxicity, is required to evaluate its potential to become a drug. Preliminary analysis of the physicochemical characteristics of eremantholide C was performed in silico. Equilibrium solubility was evaluated using the shake-flask method, at 37.0 °C, 100 rpm during 72 h in biorelevant media. The permeability was analysed using parallel artificial membrane permeability assay, at 37.0 °C, 50 rpm for 5 h. The donor compartment was composed of an eremantholide C solution in intestinal fluid simulated without enzymes, while the acceptor compartment consisted of phosphate buffer. Physicochemical characteristics predicted in silico indicated that eremantholide C has a low solubility and high permeability. In-vitro data of eremantholide C showed low solubility, with values for the dose/solubility ratio (ml): 9448.82, 10 389.61 e 15 000.00 for buffers acetate (pH 4.5), intestinal fluid simulated without enzymes (pH 6.8) and phosphate (pH 7.4), respectively. Also, it showed high permeability, with effective permeability of 30.4 × 10 -6 cm/s, a higher result compared with propranolol hydrochloride (9.23 × 10 -6 cm/s). The high permeability combined with its solubility, pharmacological activity and low toxicity demonstrate the importance of eremantholide C as a potential drug candidate. © 2017 Royal Pharmaceutical Society.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-09-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators.

Thermal inactivation of ileal loop-reactive Clostridium perfringens type A strains in phosphate buffer and beef gravy.

PubMed Central

Bradshaw, J G; Peeler, J T; Twedt, R M

1977-01-01

The thermal resistance of spore crops produced from each of two ileal loop-reactive strains of Clostridium perfringens type A was determined in two suspending vehicles consisting of 0.067 M (pH 7.0) phosphate buffer and a commercial beef gravy. D115.6 values obtained in buffer and enumerated after pretreatment with sodium ethylenediaminetetraacetate and recovery in plating medium containing lysozyme were two- to threefold greater than those obtained without this treatment. D115.6 values obtained with beef gravy were less than those obtained in buffer with or without lysozyme; however, the D98.9 and D104.4 values were 1.3 to 2 times greater than those obtained in buffer with lysozyme. The z values were within the ranges reported by previous investigators. PMID:199113

Comparison of adhesive properties of water- and phosphate-buffer-washed cottonseed meals with cottonseed protein isolate on maple and poplar veneers

USDA-ARS?s Scientific Manuscript database

Water- and phosphate buffer (35 mM Na2HPO4/NaH2PO4, pH 7.5)-washed cottonseed meals (abbreviated as WCM and BCM, respectively) could be low-cost and environmentally friendly protein-based adhesives as their preparation does not involve corrosive alkali and acid solutions that are needed for cottonse...

Toxicity of ZnO nanoparticles to Escherichia coli: mechanism and the influence of medium components.

PubMed

Li, Mei; Zhu, Lizhong; Lin, Daohui

2011-03-01

Water chemistry can be a major factor regulating the toxicity mechanism of ZnO nanoparticles (nano-ZnO) in water. The effect of five commonly used aqueous media with various chemical properties on the toxicity of nano-ZnO to Escherichia coli O111 (E. coli) was investigated, including ultrapure water, 0.85% NaCl, phosphate-buffered saline (PBS), minimal Davis (MD), and Luria-Bertani (LB). Combined results of physicochemical characterization and antibacterial tests of nano-ZnO in the five media suggest that the toxicity of nano-ZnO is mainly due to the free zinc ions and labile zinc complexes. The toxicity of nano-ZnO in the five media deceased as follows: ultrapure water > NaCl > MD > LB > PBS. The generation of precipitates (Zn(3)(PO(4))(2) in PBS) and zinc complexes (of zinc with citrate and amino acids in MD and LB, respectively) dramatically decreased the concentration of Zn(2+) ions, resulting in the lower toxicity in these media. Additionally, the isotonic and rich nutrient conditions improved the tolerance of E. coli to toxicants. Considering the dramatic difference of the toxicity of nano-ZnO in various aqueous media, the effect of water chemistry on the physicochemical properties of nanoparticles should be paid more attention in future nanotoxicity evaluations.

Expression of macrophage migration inhibitory factor and CD74 in the inner ear and middle ear in lipopolysaccharide-induced otitis media.

PubMed

Ishihara, Hisashi; Kariya, Shin; Okano, Mitsuhiro; Zhao, Pengfei; Maeda, Yukihide; Nishizaki, Kazunori

2016-10-01

Significant expression of macrophage migration inhibitory factor and its receptor (CD74) was observed in both the middle ear and inner ear in experimental otitis media in mice. Modulation of macrophage migration inhibitory factor and its signaling pathway might be useful in the management of inner ear inflammation due to otitis media. Inner ear dysfunction secondary to otitis media has been reported. However, the specific mechanisms involved are not clearly understood. The aim of this study is to investigate the expression of macrophage migration inhibitory factor and CD74 in the middle ear and inner ear in lipopolysaccharide-induced otitis media. BALB/c mice received a transtympanic injection of either lipopolysaccharide or phosphate-buffered saline (PBS). The mice were sacrificed 24 h after injection, and temporal bones were processed for polymerase chain reaction (PCR) analysis, histologic examination, and immunohistochemistry. PCR examination revealed that the lipopolysaccharide-injected mice showed a significant up-regulation of macrophage migration inhibitory factor in both the middle ear and inner ear as compared with the PBS-injected control mice. The immunohistochemical study showed positive reactions for macrophage migration inhibitory factor and CD74 in infiltrating inflammatory cells, middle ear mucosa, and inner ear in the lipopolysaccharide-injected mice.

Effects of protein and phosphate buffer concentrations on thermal denaturation of lysozyme analyzed by isoconversional method.

PubMed

Cao, X M; Tian, Y; Wang, Z Y; Liu, Y W; Wang, C X

2016-07-03

Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method.

Formation kinetics of a novel product from photolysis of cytosine in phosphate-buffered solutions

NASA Astrophysics Data System (ADS)

Wenqing, Wang; Feng, Lin; Jilan, Wu

1999-01-01

For studying the role of phosphate in the origin of life and the effect of far-ultraviolet light induced photochemical damage to RNA, DNA and its components, it was found that the photolysis of nucleobases, nucleosides and nucleotides was strongly enhanced by phosphate under the irradiation of medium pressure mercury lamp (MPML). Ultraviolet irradiation (190-220 nm) of cytosine in 0.05 mol dm -3 phosphate buffered solution at pH 8-9 leads to the production of a novel compound C 4H 6N 3O 5P in the presence of oxygen. The main photoproduct has been isolated, purified and characterized by use of 1H- and 31P-NMR spectroscopy, elemental analysis, ultraviolet and infrared spectroscopy and electron impact mass spectrometry. Phosphate effect can be inhibited by amino acids. The formation mechanism of the photoproduct and the kinetics was studied.

Analysis of the Postoperative Periarticular Environment and Influence on Sustained Drug Delivery from a Gel Formulation.

PubMed

Svirskis, Darren; Martis, Waldron; Bhusal, Prabhat; Sharma, Manisha; Stowers, Renus; Young, Simon W

2018-05-16

Regional intraarticular delivery of local anaesthetics is effective in treating postoperative pain following total knee or hip replacement. Recent research efforts have been only partially successful in achieving sustained release of the analgesic agent, in part due to limited understanding of the biological environment into which these formulations are administered. This study aimed to detail the composition and properties of postoperative periarticular fluid (PO-PAF). PO-PAF was collected from 8 patients and the composition and physicochemical properties determined. A number of components were identified which are lacking from phosphate buffered saline (PBS) or other synthetic media. The differences in composition led to variation in the physicochemical properties of PO-PAF compared with PBS. Notably, significantly lower surface tension (p<0.05) and higher buffer capacity (p<0.05) were observed in the biological fluid. We demonstrated the solubility of lidocaine is almost double in PO-PAF compared to PBS (p<0.05) and that lidocaine release from a poloxamer gelling system occurred faster into PO-PAF under both sink and non-sink conditions. Collectively, these data indicate PBS is inappropriate for the in-vitro evaluation of intraarticular drug delivery systems. The presented data describes PO-PAF and will support the future development of biorelevant media to ultimately improve in-vivo in-vitro correlation. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles.... 14433-76-2) Emulsifier, solvent, cosolvent Diammonium phosphate (CAS Reg. No. 7783-28-0) Buffer...

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles... phosphate (CAS Reg. No. 7783-28-0) Buffer, surfactant dibenzylidene sorbitol (32647-67-9) Thinning agent...

40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... di- and monohydrogen phosphate esters and the corresponding ammonium, calcium, magnesium, monoethanolamine, potassium, sodium, and zinc salts of the phosphate esters; minimum oxyethylene content is 2 moles... phosphate (CAS Reg. No. 7783-28-0) Buffer, surfactant dibenzylidene sorbitol (32647-67-9) Thinning agent...

/sup 3/H)pirenzepine and (-)-(/sup 3/H)quinuclidinyl benzilate binding to rat cerebral cortical and cardiac muscarinic cholinergic sites. I. Characterization and regulation of agonist binding to putative muscarinic subtypes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watson, M.; Yamamura, H.I.; Roeske, W.R.

The binding and regulation of selected muscarinic agonists to putative subtypes in rat cerebral cortex and heart were studied. Parallel inhibition studies of (/sup 3/H)pirenzepine ((/sup 3/H)PZ) and (-)-(/sup 3/H)quinuclidinylbenzilate ((-)-(/sup 3/H)QNB)-labeled membranes were done with and without 30 microM guanyl-5'-yl imidodiphosphate (Gpp(NH)p) at 25 degrees C in 10 mM Na-K-phosphate buffer which enhances PZ binding affinity and in modified Krebs-phosphate buffer, which mimics physiological conditions. Classical agonists such as carbachol, oxotremorine and acetylcholine inhibited (-)-(/sup 3/H)QNB binding to membranes with shallow Hill values (nH less than 1), were better fit to a 2-state model, were Gpp(NH)p-regulated and showed lowermore » affinity in modified Krebs-phosphate buffer than in 10 mM Na-K-phosphate buffer. Some agonists were not significantly better fit to a 2-state model in (/sup 3/H)PZ-labeled cortical membranes, especially in 10 mM Na-K-phosphate buffer. Whereas putative M1 and M2 binding sites distinguished by PZ possessed multiple agonist affinity states, as judged by carbachol, and agonist binding to (/sup 3/H)PZ-labeled sites were Gpp(NH)p modulated, the partial agonist pilocarpine and nonclassical agonist McN-A-343 (3-(m-chlorophenylcarbamoyloxy)-2-butynyl trimethylammonium chloride) showed little Gpp(NH)p-induced shift in (/sup 3/H)PZ-labeled cortical membranes in physiological conditions. Agonist binding to (-)-(/sup 3/H)QNB-labeled putative M2 cardiac sites was more sensitive to Gpp(NH)p than (-)-(/sup 3/H)QNB-labeled cortical sites. Carbachol and acetylcholine showed significant selectivity for putative M2 sites.« less

ELISA (Enzyme-linked Immunosorbent Assay) to Detect Humoral Antibodies Specific for Clostridium botulinum Type A Neurotoxin

DTIC Science & Technology

1985-11-19

10.6). Unbound toxoid was removed by washing three times with phosphate-buffered saline (pH 7.4) containing 0.05% Triton X-100 (Eastman Organic...MD) in phosphate-buffered saline was added. After a 90 min incubation period at 37*C, the excess conjugate was removed by washing each well three times...3. Cardella, M. A. 1964. Botulinum toxoids, p. 113-129. In K . H. Lewis and K . Cassel, Jr., (ed.), Botulism. U. S. Department of Health, Education

Analysis of Fatty Acid and Growth Profiles in Ten Shewanella spp. to Associate Phylogenetic Relationships

DTIC Science & Technology

2015-10-25

in a defined medium composed of half-strength Marine Broth adjusted to pH 6, 7, or 8 in a 50 mM phosphate buffer, both growth characteristics and...work had broad phylogenetic diversity (Fig. 1) and were isolated from mostly marine environments. S. putrefaciens was the only strain that was not...the defined medium that supported growth of most of the strains tested was marine broth diluted to half strength with 50 mM phosphate buffer (½-MB

Innovative Microsystems: Novel Nanostructures to Capture Circulating Breast Cancer Cells

DTIC Science & Technology

2009-05-01

temperature to promote a Schiff-base reaction. Recombinant protein G from E . coli (Zymed Lab Inc.) 50 μg/ml in Ca- and Mg-free phosphate-buffered...recombinant protein G from E . coli (Zymed Lab Inc.), at a concentration of 50 mg ml1 in 1 PBS, is incubated on the activated surface overnight at 4 C...reaction. Recombinant protein G from E . coli (Zymed Lab Inc.) 50 μg/ml in Ca- and Mg-free phosphate-buffered saline (CMF-PBS), is incubated on the

Reductive dechlorination of carbon tetrachloride using buffered alkaline ascorbic acid.

PubMed

Lin, Ya-Ting; Liang, Chenju

2015-10-01

Alkaline ascorbic acid (AA) was recently discovered as a novel in-situ chemical reduction (ISCR) reagent for remediating chlorinated solvents in the subsurface. For this ISCR process, the maintenance of an alkaline pH is essential. This study investigated the possibility of the reduction of carbon tetrachloride (CT) using alkaline AA solution buffered by phosphate and by NaOH. The results indicated that CT was reduced by AA, and chloroform (CF) was a major byproduct at a phosphate buffered pH of 12. However, CT was completely reduced by AA in 2M NaOH without CF formation. In the presence of iron/soil minerals, iron could be reduced by AA and Fe(2+) tends to precipitate on the mineral surface to accelerate CT degradation. A simultaneous transfer of hydrogenolysis and dichloroelimination would occur under phosphate buffered pH 12. This implies that a high alkaline environment is a crucial factor for maintaining the dominant pathway of two electron transfer from dianionic AA to dehydroascorbic acid, and to undergo dichloroelimination of CT. Moreover, threonic acid and oxalic acid were identified to be the major AA decomposition products in alkaline solutions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Basidiospore and Protoplast Regeneration from Raised Fruiting Bodies of Pathogenic Ganoderma boninense.

PubMed

Govender, Nisha T; Mahmood, Maziah; Seman, Idris A; Mui-Yun, Wong

2016-08-26

Ganoderma boninense, a phytopathogenic white rot fungus had sought minimal genetic characterizations despite huge biotechnological potentials. Thus, efficient collection of fruiting body, basidiospore and protoplast of G. boninense is described. Matured basidiocarp raised under the glasshouse conditions yielded a total of 8.3 × 104 basidiospores/ml using the low speed centrifugation technique. Mycelium aged 3-day-old treated under an incubation period of 3 h in lysing enzyme from Trichoderma harzianum (10 mg/ml) suspended in osmotic stabilizer (0.6 M potassium chloride and 20 mM dipotassium phosphate buffer) yielded the highest number of viable protoplasts (8.9 × 106 single colonies) among all possible combinations tested (regeneration media, age of mycelium, osmotic stabilizer, digestive enzyme and incubation period).

Double-pass Mach-Zehnder fiber interferometer pH sensor.

PubMed

Tou, Zhi Qiang; Chan, Chi Chiu; Hong, Jesmond; Png, Shermaine; Eddie, Khay Ming Tan; Tan, Terence Aik Huang

2014-04-01

A biocompatible fiber-optic pH sensor based on a unique double-pass Mach-Zehnder interferometer is proposed. pH responsive poly(2-hydroxyethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate) hydrogel coating on the fiber swells/deswells in response to local pH, leading to refractive index changes that manifest as shifting of interference dips in the optical spectrum. The pH sensor is tested in spiked phosphate buffer saline and demonstrates high sensitivity of 1.71  nm/pH, pH 0.004 limit of detection with good responsiveness, repeatability, and stability. The proposed sensor has been successfully applied in monitoring the media pH in cell culture experiments to investigate the relationship between pH and cancer cell growth.

Effects of protein and phosphate buffer concentrations on thermal denaturation of lysozyme analyzed by isoconversional method

PubMed Central

Cao, X.M.; Tian, Y.; Wang, Z.Y.; Liu, Y.W.; Wang, C.X.

2016-01-01

ABSTRACT Thermal denaturation of lysozymes was studied as a function of protein concentration, phosphate buffer concentration, and scan rate using differential scanning calorimetry (DSC), which was then analyzed by the isoconversional method. The results showed that lysozyme thermal denaturation was only slightly affected by the protein concentration and scan rate. When the protein concentration and scan rate increased, the denaturation temperature (Tm) also increased accordingly. On the contrary, the Tm decreased with the increase of phosphate buffer concentration. The denaturation process of lysozymes was accelatated and the thermal stability was reduced with the increase of phosphate concentration. One part of degeneration process was not reversible where the aggregation occurred. The other part was reversible. The apparent activation energy (Ea) was computed by the isoconversional method. It decreased with the increase of the conversion ratio (α). The observed denaturation process could not be described by a simple reaction mechanism. It was not a process involving 2 standard reversible states, but a multi-step process. The new opportunities for investigating the kinetics process of protein denaturation can be supplied by this novel isoconversional method. PMID:27459596

Generation of Reduced Nicotinamide Adenine Dinucleotide for Nitrate Reduction in Green Leaves 1

PubMed Central

Klepper, Lowell; Flesher, Donna; Hageman, R. H.

1971-01-01

An in vivo assay of nitrate reductase activity was developed by vacuum infiltration of leaf discs or sections with a solution of 0.2 m KNO3 (with or without phosphate buffer, pH 7.5) and incubation of the infiltrated tissue and medium under essentially anaerobic conditions in the dark. Nitrite production, for computing enzyme activity, was determined on aliquots of the incubation media, removed at intervals. By adding, separately, various metabolites of the glycolytic, pentose phosphate, and citric acid pathways to the infiltrating media, it was possible to use the in vivo assay to determine the prime source of reduced nicotinamide adenine dinucleotide (NADH) required by the cytoplasmically located NADH-specific nitrate reductase. It was concluded that sugars that migrate from the chloroplast to the cytoplasm were the prime source of energy and that the oxidation of glyceraldehyde 3-phosphate was ultimately the in vivo source of NADH for nitrate reduction. This conclusion was supported by experiments that included: inhibition studies with iodoacetate; in vitro studies that established the presence and functionality of the requisite enzymes; and studies showing the effect of light (photosynthate) and exogenous carbohydrate on loss of endogenous nitrate from plant tissue. The level of nitrate reductase activity obtained with the in vitro assay is higher (2.5- to 20-fold) than with the in vivo assay for most plant species. The work done to date would indicate that the in vivo assays are proportional to the in vitro assays with respect to ranking genotypes for nitrate-reducing potential of a given species. The in vivo assay is especially useful in studying nitrate assimilation in species like giant ragweed from which only traces of active nitrate reductase can be extracted. PMID:16657841

Visualising phase change in a brushite-based calcium phosphate ceramic

PubMed Central

Bannerman, A.; Williams, R. L.; Cox, S. C.; Grover, L. M.

2016-01-01

The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s – Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media. PMID:27604149

Visualising phase change in a brushite-based calcium phosphate ceramic

NASA Astrophysics Data System (ADS)

Bannerman, A.; Williams, R. L.; Cox, S. C.; Grover, L. M.

2016-09-01

The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s - Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media.

Functional PEG–PAMAM-Tetraphosphonate Capped NaLnF4 Nanoparticles and their Colloidal Stability in Phosphate Buffer

PubMed Central

2015-01-01

Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (Mn = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (Mn = 2000) and biotin-terminated PEG (Mn = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000–PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir2012, 28, 12861−1287022906305) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline. PMID:24898128

Functional PEG-PAMAM-tetraphosphonate capped NaLnF₄ nanoparticles and their colloidal stability in phosphate buffer.

PubMed

Zhao, Guangyao; Tong, Lemuel; Cao, Pengpeng; Nitz, Mark; Winnik, Mitchell A

2014-06-17

Developing surface coatings for NaLnF4 nanoparticles (NPs) that provide long-term stability in solutions containing competitive ions such as phosphate remains challenging. An amine-functional polyamidoamine tetraphosphonate (NH2-PAMAM-4P) as a multidentate ligand for these NPs has been synthesized and characterized as a ligand for the surface of NaGdF4 and NaTbF4 nanoparticles. A two-step ligand exchange protocol was developed for introduction of the NH2-PAMAM-4P ligand on oleate-capped NaLnF4 NPs. The NPs were first treated with methoxy-poly(ethylene glycol)-monophosphoric acid (M(n) = 750) in tetrahydrofuran. The mPEG750-OPO3-capped NPs were stable colloidal solutions in water, where they could be ligand-exchanged with NH2-PAMAM-4P. The surface amine groups on the NPs were available for derivatization to attach methoxy-PEG (M(n) = 2000) and biotin-terminated PEG (M(n) = 2000) chains. The surface coverage of ligands on the NPs was examined by thermal gravimetric analysis, and by a HABA analysis for biotin-containing NPs. Colloidal stability of the NPs was examined by dynamic light scattering. NaGdF4 and NaTbF4 NPs capped with mPEG2000-PAMAM-4P showed colloidal stability in DI water and in phosphate buffer (10 mM, pH 7.4). A direct comparison with NaTbF4 NPs capped with a mPEG2000-lysine-based tetradentate ligand that we reported previously (Langmuir 2012, 28, 12861-12870) showed that both ligands provided long-term stability in phosphate buffer, but that the lysine-based ligand provided better stability in phosphate-buffered saline.

Quantitative and qualitative optimization of allergen extraction from peanut and selected tree nuts. Part 2. Optimization of buffer and ionic strength using a full factorial experimental design.

PubMed

L'Hocine, Lamia; Pitre, Mélanie

2016-03-01

A full factorial design was used to assess the single and interactive effects of three non-denaturing aqueous (phosphate, borate, and carbonate) buffers at various ionic strengths (I) on allergen extractability from and immunoglobulin E (IgE) immunoreactivity of peanut, almond, hazelnut, and pistachio. The results indicated that the type and ionic strength of the buffer had different effects on protein recovery from the nuts under study. Substantial differences in protein profiles, abundance, and IgE-binding intensity with different combinations of pH and ionic strength were found. A significant interaction between pH and ionic strength was observed for pistachio and almond. The optimal buffer system conditions, which maximized the IgE-binding efficiency of allergens and provided satisfactory to superior protein recovery yield and profiles, were carbonate buffer at an ionic strength of I=0.075 for peanut, carbonate buffer at I=0.15 for almond, phosphate buffer at I=0.5 for hazelnut, and borate at I=0.15 for pistachio. The buffer type and its ionic strength could be manipulated to achieve the selective solubility of desired allergens. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Proton transport by phosphate diffusion--a mechanism of facilitated CO2 transfer

PubMed Central

1976-01-01

We have measured CO2 fluxes across phosphate solutions at different carbonic anhydrase concentrations, bicarbonate concentration gradients, phosphate concentrations, and mobilities. Temperature was 22-25 degrees C, the pH of the phosphate solutions was 7.0-7.3. We found that under physiological conditions of pH and pCO2 a facilitated diffusion of CO2 occurs in addition to free diffusion when (a) sufficient carbonic anhydrase is present, and (b) a concentration gradient of HCO3- is established along with a pCO2 gradient, and (c) the phosphate buffer has a mobility comparable to that of bicarbonate. When the phosphate was immobilized by attaching 0.25-mm-long cellulose particles, no facilitation of CO2 diffusion was detectable. A mechanism of facilitated CO2 diffusion in phosphate solutions analogous to that in albumin solutions was proposed on the basis of these findings: bicarbonate diffusion together with a facilitated proton transport by phosphate diffusion. A mathematical model of this mechanism was formulated. The CO2 fluxed predicted by the model agree quantitatively with the experimentally determined fluxes. It is concluded that a highly effective proton transport mechanism acts in solutions of mobile phosphate buffers. By this mechanism; CO2 transfer may be increased up to fivefold and proton transfer may be increased to 10,000-fold. PMID:6619

Variation in Supersaturation and Phase Behavior of Ezetimibe Amorphous Solid Dispersions upon Dissolution in Different Biorelevant Media.

PubMed

Elkhabaz, Ahmed; Sarkar, Sreya; Dinh, Janny K; Simpson, Garth J; Taylor, Lynne S

2018-01-02

The delivery of poorly water-soluble drugs using amorphous solid dispersions (ASDs) has been widely acknowledged as a promising strategy for enhancing oral bioavailability. Upon dissolution, ASDs have accelerated dissolution rates and yield supersaturated solutions leading to higher apparent solubilities. Understanding the complex phase behavior of ASDs during dissolution is crucial for developing an effective formulation. Since the absorption of a lipophilic, high permeability drug is determined primarily by the intraluminal dissolution process and the final concentration achieved, there is a need for evaluation in biorelevant dissolution media that simulate both fasting and fed gastrointestinal states. In this study, using ezetimibe as a model drug, three different ASDs were prepared using poly(acrylic acid) (PAA), polyvinylpyrrolidone (PVP), and hydroxypropyl methylcellulose acetyl succinate (HPMC-AS). Dissolution of ASDs was carried out in sodium phosphate buffer, fed-state simulated intestinal fluid (FeSSIF), and Ensure Plus to evaluate the impact of different dissolution media on release profile, supersaturation, and phase behavior. The supersaturation level and crystallization kinetics varied among the dispersions and were found to be highly dependent on the medium employed. The presence of solubilizing additives in biorelevant media greatly affected the generation and stabilization of supersaturated solutions. Second harmonic generation microscopy was found to enable the detection of crystals in all media including the highly turbid Ensure Plus system. In conclusion, it is important to evaluate the impact of complex biorelevant media on the dissolution performance of ASDs to better design supersaturating formulations for oral delivery.

Influence of dissolution media pH and USP1 basket speed on erosion and disintegration characteristics of immediate release metformin hydrochloride tablets.

PubMed

Desai, Divyakant; Wong, Benjamin; Huang, Yande; Tang, Dan; Hemenway, Jeffrey; Paruchuri, Srinivasa; Guo, Hang; Hsieh, Daniel; Timmins, Peter

2015-01-01

To investigate the influence of the pH of the dissolution medium on immediate release 850 mg metformin hydrochloride tablets. A traditional wet granulation method was used to manufacture metformin hydrochloride tablets with or without a disintegrant. Tablet dissolution was conducted using the USP apparatus I at 100 rpm. In spite of its pH-independent high solubility, metformin hydrochloride tablets dissolved significantly slower in 0.1 N HCl (pH 1.2) and 50 mM pH 4.5 acetate buffer compared with 50 mM pH 6.8 phosphate buffer, the dissolution medium in the USP. Metformin hydrochloride API compressed into a round 1200 mg disk showed a similar trend. When basket rotation speed was increased from 100 to 250 rpm, the dissolution of metformin hydrochloride tablets was similar in all three media. Incorporation of 2% w/w crospovidone in the tablet formulation improved the dissolution although the pH-dependent trend was still evident, but incorporation of 2% w/w croscarmellose sodium resulted in rapid pH-independent tablet dissolution. In absence of a disintegrant in the tablet formulation, the dissolution was governed by the erosion-diffusion process. Even for a highly soluble drug, a super-disintegrant was needed in the formulation to overcome the diffusion layer limitation and change the dissolution mechanism from erosion-diffusion to disintegration.

Coatings from blends of Eudragit® RL and L55: a novel approach in pH-controlled drug release.

PubMed

Wulff, R; Leopold, C S

2014-12-10

The aim of the present study was to investigate the drug release from theophylline pellets coated with blends of quaternary polymethacrylate and methacrylic acid-ethyl acrylate copolymers. Pellets were coated with blends of Eudragit(®) RL PO (RL) and Eudragit(®) L 100-55 (L55) in either organic solution or aqueous dispersion at various copolymer ratios. Generally, the coatings were less permeable for theophylline in phosphate buffer pH 6.8 than they were in hydrochloric acid pH 1.2. Further dissolution experiments revealed that the differences in drug release are caused by the different pH values. A design of experiments for historical data was performed on drug release data of pellets with different coating levels and blend ratios of RL and L55. Drug release in hydrochloric acid was predominantly affected by the coating level, whereas for drug release in phosphate buffer pH 6.8 the blend ratio was the determining factor. As expected, dissolution experiments at different pH values showed that drug release depends on the ratio of dissociated L55 to RL because ionization is a requirement for the functional groups to interact. With the dissolution test for delayed-release solid dosage forms (Ph. Eur.) it was demonstrated that the unique release behavior in neutral media is preserved after the exposition to hydrochloric acid. These findings indicate that the combination of RL and L55 in coatings prepared from solutions is a promising approach for controlled drug release. Copyright © 2014 Elsevier B.V. All rights reserved.

The effect of ethylenediaminetetraacetic acid on heat resistance and recovery of Clostridium sporogenes PA 3679 spores treated in HTST conditions.

PubMed

Silla Santos, M H; Torres Zarzo, J

1997-03-03

The effect of ethylenediaminetetraacetic acid (EDTA) on the heat resistance of Clostridium sporogenes PA 3679 spores was studied. EDTA was added to heating substrates and recovery media in order to establish which stage of the heat treatment registered the greatest EDTA activity. The heating substrates assayed were phosphate buffer (pH 7.0) and white asparagus purée, at natural pH (5.8) and acidified with citric acid and glucono-delta-lactone (GDL) to pH 5.5, 5.0 and 4.5. Recovery of survivors was carried out in MPA3679A medium in various conditions of acidification with citric and GDL (250 and 500 ppm), at pH 7.5 6.5 and 6.0. The results show greater activity of EDTA on spores when it was applied in recovery of heat injured spores, than during heating. The strongest influence of EDTA during heating was found in phosphate buffer (pH 7.0), with the effect being most evident at 121 and 126 degrees C, and in asparagus purée, at 121 degrees C and pH 5.8 rather than acidified. In recovery, the inhibiting activity of EDTA was more evident in spores subjected to more severe heat treatment, either by increasing the exposure time or by raising the temperature to 130 or 135 degrees C. The pH level of the recovery medium also affected the antimicrobial activity of EDTA, which had a greater inhibiting effect at pH 7.5 than at lower pH levels (6.5, 6.0).

Recovery of a marker strain of Escherichia coli from ozonated water by membrane filtration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finch, G.R.; Stiles, M.E.; Smith, D.W.

1987-12-01

Selective and nonselective growth media were evaluated at two incubation temperatures, 35 and 44.5 degrees C, for the recovery of a nalidixic acid-resistant marker strain of Escherichia coli ATCC 11775 by membrane filtration from ozonated 0.05 M phosphate buffer (pH 6.9). There were significantly fewer bacteria recovered with the standard m-FC agar when compared with the same growth medium prepared without bile salts and rosolic acid. This effect was particularly noticeable at the elevated incubation temperature of 44.5 degrees C. These findings are contrary to previous work which concluded that the standard American Public Health Association membrane filtration procedure ismore » suitable for recovery of fecal coliform indicator bacteria from ozonated wastewater.« less

Control of brown stain: in Eastern white pine

Treesearch

Robert E. Stutz; Peter Koch; Millard L. Oldham

1961-01-01

Degrade caused by brown stain and blue stain in eastern white pine was virtually eliminated by the use of sap stain chemicals and sodium azide. Combinations of buffered sodium azide with both sodium pentachlorophenate plus borax and buffered ethyl mercury phosphate were effective.

Enhanced stability of superparamagnetic iron oxide nanoparticles in biological media using a pH adjusted-BSA adsorption protocol

NASA Astrophysics Data System (ADS)

Yu, Si-Ming; Laromaine, Anna; Roig, Anna

2014-07-01

Superparamagnetic iron oxide nanoparticles (SPIONs) are widely used for biological applications due to their unique properties compared to their bulk counterparts, simplified SPIONs stabilization protocols applicable for a wide spectra of biological media remains a challenging issue. In this work, SPIONs with different surface coatings, tetramethylammonium hydroxide-coated SPIONs (T-SPIONs), and citrate-coated SPIONs (C-SPIONs) were synthesized by a facile, rapid and cost effective microwave-assisted method. C-SPIONs show robust stability in biological media of phosphate buffered saline and Roswell Park Memorial Institute Medium, while destabilize in DMEM. T-SPIONs were found to aggregate rapidly and significantly in all tested media. Then, a modified pH adjusted-BSA adsorption protocol and an addition of excess trisodium citrate dihydrate (Na3Cit) were used to enhance their stability in the media. The BSA adsorption protocol showed great efficiency in stabilizing the dispersed state of both SPIONs in the tested media, while the addition of excess Na3Cit showed limited effect, and it was only applicable for C-SPIONs. The formed BSA layer on SPIONs could be imaged by negative staining TEM, and revealed by Cryo-TEM, FTIR, DLS, and the zeta potential measurements. Results indicated that BSA forms a monolayer of a thickness of about 3 ± 1 nm and BSA interacts with C-SPIONs and T-SPIONs through their coating, rather than by replacing them. This synthetic method and stabilization protocol offer a general methodology to obtain SPIONs with a variety of surfactants, stable in different biological media in few minutes.

Developing procedures for the large-scale purification of human serum butyrylcholinesterase.

PubMed

Saxena, Ashima; Luo, Chunyuan; Doctor, Bhupendra P

2008-10-01

Human serum butyrylcholinesterase (Hu BChE) is the most viable candidate for the prophylactic treatment of organophosphate poisoning. A dose of 200 mg/70 kg is predicted to protect humans against 2x LD(50) of soman. Therefore, the aim of this study was to develop procedures for the purification of gram quantities of this enzyme from outdated human plasma or Cohn Fraction IV-4. The purification of Hu BChE was accomplished by batch adsorption on procainamide-Sepharose-CL-4B affinity gel followed by ion-exchange chromatography on a DEAE-Sepharose column. For the purification of enzyme from Cohn Fraction IV-4, it was resuspended in 25 mM sodium phosphate buffer, pH 8.0, and fat was removed by decantation, prior to batch adsorption on procainamide-Sepharose gel. In both cases, the procainamide gel was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0, containing 0.05 M NaCl, and the enzyme was eluted with the same buffer containing 0.1 M procainamide. The enzyme was dialyzed and the pH was adjusted to 4.0 before loading on the DEAE column equilibrated in sodium acetate buffer, pH 4.0. The column was thoroughly washed with 25 mM sodium phosphate buffer, pH 8.0 containing 0.05 M NaCl before elution with a gradient of 0.05-0.2M NaCl in the same buffer. The purity of the enzyme following these steps ranged from 20% to 40%. The purity of the enzyme increased to >90% by chromatography on an analytical procainamide affinity column. Results show that Cohn Fraction IV-4 is a much better source than plasma for the large-scale isolation of purified Hu BChE.

Dissolution enhancement of atorvastatin calcium by co-grinding technique.

PubMed

Prabhu, Priyanka; Patravale, Vandana

2016-08-01

Atorvastatin calcium (AC) is a BCS class II drug which shows poor bioavailability due to inadequate dissolution. Solid dispersions present a promising option to enhance the solubility of poorly soluble drugs. Co-grinding with hydrophilic excipients is an easy and economical technique to improve the solubility of poorly soluble drugs and is free from usage of organic solvents. The aim of the present study was to explore novel carrier VBP-1 (organosulphur compound) for formulating a solid dispersion by using a simple, commercially viable co-grinding technique to enhance the dissolution of AC and to develop an oral formulation of the same. Composition of the solid dispersion was optimized based on the release profile in pH 1.2 buffer. The optimized solid dispersion was further characterized for flow properties, DSC, FTIR spectroscopy, XRD, contact angle, SEM studies and release profile in phosphate buffer pH 6.8. The developed solid dispersion gave similar release profile as the innovator formulation (Lipitor® tablets) in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed solid dispersion was formulated into hard gelatin capsules (size 3). The developed capsules were found to give similar release as the innovator formulation in both pH 1.2 buffer and phosphate buffer pH 6.8. The developed capsules were found to be stable for a period of 6 months. Anti-hyperlipidemic efficacy studies in rats showed higher reduction in cholesterol and triglyceride levels by the developed capsules in comparison to pure AC. In conclusion, novel carrier VBP-1 was successfully employed to enhance the dissolution of AC using co-grinding technique.

Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

DOEpatents

Aines, Roger D

2015-03-31

A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

Catalyst functionalized buffer sorbent pebbles for rapid separation of carbon dioxide from gas mixtures

DOEpatents

Aines, Roger D.

2013-03-12

A method for separating CO.sub.2 from gas mixtures uses a slurried media impregnated with buffer compounds and coating the solid media with a catalyst or enzyme that promotes the transformation of CO.sub.2 to carbonic acid. Buffer sorbent pebbles with a catalyst or enzyme coating are provided for rapid separation of CO.sub.2 from gas mixtures.

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase.

PubMed

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes' ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion.

Study of a hydraulic dicalcium phosphate dihydrate/calcium oxide-based cement for dental applications.

PubMed

el-Briak, Hasna; Durand, Denis; Nurit, Josiane; Munier, Sylvie; Pauvert, Bernard; Boudeville, Phillipe

2002-01-01

By mixing CaHPO(4) x 2H(2)O (DCPD) and CaO with water or sodium phosphate buffers as liquid phase, a calcium phosphate cement was obtained. Its physical and mechanical properties, such as compressive strength, initial and final setting times, cohesion time, dough time, swelling time, dimensional and thermal behavior, and injectability were investigated by varying different parameters such as liquid to powder (L/P) ratio (0.35-0.7 ml g(-1)), molar calcium to phosphate (Ca/P) ratio (1.67-2.5) and the pH (4, 7, and 9) and the concentration (0-1 M) of the sodium phosphate buffer. The best results were obtained with the pH 7 sodium phosphate buffer at the concentration of 0.75 M. With this liquid phase, physical and mechanical properties depended on the Ca/P and L/P ratios, varying from 3 to 11 MPa (compressive strength), 6 to 10 min (initial setting time), 11 to 15 min (final setting time), 15 to 30 min (swelling time), 7 to 20 min (time of 100% injectability). The dough or working time was over 16 min. This cement expanded during its setting (1.2-5 % according to Ca/P and L/P ratios); this would allow a tight filling. Given the mechanical and rheological properties of this new DCPD/CaO-based cement, its use as root canal sealing material can be considered as classical calcium hydroxide or ZnO/eugenol-based pastes, without or with a gutta-percha point. Copyright 2002 Wiley Periodicals, Inc. J Biomed Mater Res (Appl Biomater) 63: 447-453, 2002

Photophysical investigations of squaraine and cyanine dyes and their interaction with bovine serum albumin

NASA Astrophysics Data System (ADS)

Saikiran, M.; Sato, D.; Pandey, S. S.; Kato, T.

2016-04-01

A model far-red sensitive symmetrical squaraine dye (SQ-3) and unsymmetrical near infra-red sensitive cyanine dye (UCD-1) bearing direct-COOH functionalized indole ring were synthesized, characterized and subjected to photophysical investigations including their interaction with bovine serum albumin (BSA) as a model protein in phosphate buffer solution (PBS). Both of the dyes exhibit strong interaction with BSA in phosphate buffer with high apparent binding constant. A judicious tuning of hydrophobic main backbone with reactive functionality for associative interaction with active site of BSA has been found to be necessary for BSA detection in PBS.

Optimizing buffering chemistry to maintain near neutral pH of broiler feed during pre-enrichment for Salmonella.

PubMed

Berrang, M E; Cosby, D E; Cox, N A; Cason, J A; Richardson, K E

2015-12-01

Salmonella is a human pathogen that can accompany live broilers to the slaughter plant, contaminating fully processed carcasses. Feed is one potential source of Salmonella to growing broilers. Monitoring feed for the presence of Salmonella is part of good agricultural practice. The first step in culturing feed for Salmonella (which may be at low numbers and sub-lethally stressed) is to add it to a pre-enrichment broth which is incubated for 24 h. During the course of pre-enrichment, extraneous bacteria metabolize carbohydrates in some feed and excrete acidic byproducts, causing the pH to drop dramatically. An acidic pre-enrichment pH can injure or kill Salmonella resulting in a failure to detect, even if it is present and available to infect chickens. The objective of this study was to test an array of buffering chemistries to prevent formation of an injurious acidic environment during pre-enrichment of feed in peptone water. Five grams of feed were added to 45 mL of peptone water buffered with carbonate, Tris pH 8, and phosphate buffering ingredients individually and in combination. Feed was subjected to a pre-enrichment at 35°C for 24 h; pH was measured at 0, 18, and 24 h. Standard phosphate buffering ingredients at concentrations up to 4 times the normal formulation were unable to fully prevent acidic conditions. Likewise, carbonate and Tris pH 8 were not fully effective. The combination of phosphate, carbonate, and Tris pH 8 was the most effective buffer tested. It is recommended that a highly buffered pre-enrichment broth be used to examine feed for the presence of Salmonella. Published by Oxford University Press on behalf of Poultry Science Association 2015. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Electrochemical studies on zirconium and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in simulated physiologic media.

PubMed

Oliveira, Nilson T C; Biaggio, Sonia R; Rocha-Filho, Romeu C; Bocchi, Nerilso

2005-09-01

Different electrochemical studies were carried out for Zr and its biocompatible alloys Ti-50Zr at.% and Zr-2.5Nb wt.% in solutions simulating physiologic media, Ringer and PBS (phosphate buffered saline) solutions. The results from rest-potential measurements showed that the three materials are spontaneously passivated in both solutions and that the Ti-50Zr alloy has the greatest tendency for spontaneous oxide formation. Some corrosion parameters (such as the pitting and repassivation potentials) were obtained via cyclic voltammetry in both solutions, revealing that the Ti-50Zr has the best corrosion protection while Zr has the worst. On the other hand, the pre-anodization (up to 8 V vs. SCE) of the alloys in a 0.15 mol/L Na2SO4 solution led to a significant improvement in their protection against pitting corrosion when exposed to the Ringer solution. Elemental analyses by EDX showed that during pitting corrosion, there is no preferential corrosion of any of the alloying elements (Zr, Ti, Nb). Copyright (c) 2005 Wiley Periodicals, Inc.

Human oocyte cryopreservation: 5-year experience with a sodium-depleted slow freezing method.

PubMed

Boldt, Jeffrey; Tidswell, Non; Sayers, Amy; Kilani, Rami; Cline, Donald

2006-07-01

A slow freezing/rapid thawing method for the cryopreservation of human oocytes has been employed using a sodium-depleted culture media. In 53 frozen egg-embryo transfer (FEET) cycles, a 60.4% survival rate post-thaw was obtained and a 62.0% fertilization rate following intracytoplasmic sperm injection. Overall pregnancy rates were 26.4% per thaw attempt, 30.4% per patient, and 32.6% per embryo transfer. Pregnancy rates using sodium-depleted phosphate-buffered saline (PBS) as the base medium were 20.0% per thaw, 21.7% per patient, and 26.3% per transfer. With sodium-depleted modified human tubal fluid (mHTF) as the base for the cryopreservation medium, rates were 32.1% per thaw attempt, 39.1% per patient, 37.5% per transfer. The overall implantation rates were 4.2% per thawed oocyte and 13.6% per embryo, (PBS: 3.0% per egg, 10.6% per embryo; mHTF:5.3% per oocyte; 15.9% per embryo). These data indicate that the use of a sodium-depleted media with slow freezing and rapid thawing can yield acceptable pregnancy rates after FEET.

Ion sensitivity of large-area epitaxial graphene film on SiC substrate

NASA Astrophysics Data System (ADS)

Mitsuno, Takanori; Taniguchi, Yoshiaki; Ohno, Yasuhide; Nagase, Masao

2017-11-01

We investigated the intrinsic ion sensitivity of graphene field-effect transistors (FETs) fabricated by a resist-free stencil mask lithography process from a large-scale graphene film epitaxially grown on a SiC substrate. A pH-adjusted phosphate-buffered solution was used for the measurement to eliminate the interference of other ions on the graphene FET's ion sensitivity. The charge neutrality point shifted negligibly with changing pH for the pH-adjusted phosphate-buffered solution, whereas for the mixed buffer solution, it shifted toward the negative gate voltage owing to the decrease in the concentration of phthalate ions. This phenomenon is contrary to that observed in previous reports. Overall, our results indicate that the graphene film is intrinsically insensitive to ions except for those with functional groups that interact with the graphene surface.

In vitro digestion of curcuminoid-loaded lipid nanoparticles

NASA Astrophysics Data System (ADS)

Noack, Andreas; Oidtmann, Johannes; Kutza, Johannes; Mäder, Karsten

2012-09-01

Curcuminoid-loaded lipid nanoparticles were produced by melt homogenization. The used lipid matrices were medium chain triglycerides, trimyristin (TM), and tristearin. The mean particle size of the preparations was between 130 and 180 nm. The incorporated curcuminoids revealed a good stability over a period of 12 months. The curcuminoid-loaded lipid nanoparticles were intended for the oral delivery of curcuminoids. Therefore, the fate of the triglyceride matrix in simulated gastric and simulated intestinal media under the influence of pepsin and pancreatin, respectively, was assessed. The degradation of the triglycerides was monitored by the pH-stat method and with high performance thin layer chromatography in connection with spectrodensitometry to quantify the different lipid fractions. The TM nanoparticles were not degraded in simulated gastric fluid (SGF), but the decomposition of the triglyceride matrix was rapid in the intestinal media. The digestion process was faster in the simulated fed state medium compared to the simulated fasted state medium. Additionally, the stability of the incorporated drug was tested in the respective physiological media. The curcuminoids showed an overall good stability in the different test media. The release of the curcuminoids from the lipid nanoparticles was determined by fluorescence imaging techniques. A slow release of the drug was found in phosphate buffer. In contrast, a more distinct release of the curcuminoids was verifiable in SGF and in simulated intestinal fluids. Overall, it was considered that the transfer of the drug into the outer media was mainly triggered by the lipid degradation and not by drug release.

Comparison of culture media for the laboratory diagnosis of chancroid.

PubMed

Pillay, A; Hoosen, A A; Loykissoonlal, D; Glock, C; Odhav, B; Sturm, A W

1998-11-01

Seven different agar-based media were compared to determine the optimal set of culture media for primary isolation of Haemophilus ducreyi. Also, a new method for sampling genital ulcers -- with a disposable sterile plastic loop -- and processing specimens that provides a standardised inoculum for culture of H. ducreyi on various media is described. A total of 202 patients with genital ulcer disease was enrolled in this study. A sterile swab or plastic loop was used to sample the base of the ulcers and ulcer material was suspended in sterile phosphate-buffered saline. A 100-microl sample of this suspension was mixed with an equal volume of tryptic soy broth containing IsoVitaleX and centrifuged for 1 min. This suspension was used to inoculate the different media. Plates were incubated at 33 degrees C in micro-aerophilic conditions and examined for growth of H. ducreyi after 48 h. Of the 202 specimens, 77 (38.1%) were culture positive for H. ducreyi. None of the agar bases supported the growth of all H. ducreyi strains. Based on this observation, we recommend the universal use of Mueller-Hinton agar base supplemented with chocolate horse blood and IsovitaleX (MH-HBC) and Columbia agar base supplemented with bovine haemoglobin, activated charcoal, fetal calf serum and IsovitaleX (C-HgCh) to enable comparison of prevalence figures for chancroid. In addition, the novel sampling technique described in this study eliminates sampling bias normally associated with genital ulcer specimens.

Influence of vehicle properties and excipients on hydrolytic and photochemical stability of curcumin in preparations containing Pluronics: studies of curcumin and curcuminoids XLVIII.

PubMed

Singh, R; Kristensen, S; Tønnesen, H H

2013-03-01

The influence of vehicle properties and excipients on the hydrolytic and photochemical stability of curcumin in Pluronic preparations, and the interactions between curcumin and Pluronics was investigated. Curcumin was found to be degraded by general acid-base catalyzed hydrolytic degradation in alkaline preparations. The degradation rate of curcumin was higher in carbonate buffer than in phosphate buffer (pH 8.8), while it was higher in phosphate buffer than in citrate buffer (pH 7.8). At pH 8.0-8.8 the degradation rate of curcumin increased compared to preparations with pH <8.0. The stabilizing effect of the Pluronics against hydrolytic degradation of curcumin was only detectable at pH 8.0-8.8, and it was highest for F127 and lowest for P85, in phosphate buffer pH 8.8. An increase in the ionic strength increased the stabilization against hydrolytic degradation of curcumin by all Pluronics. Addition of ethanol decreased the hydrolytic stability of curcumin in all Pluronics. Addition of PEG 400 decreased the hydrolytic stability in preparation with either P123 or F127 while the degradation in preparations with P85 remained the same as in P85 preparations without PEG 400. Vehicle properties and excipients did not to any large degree influence the spectroscopic properties or the photostability of curcumin in Pluronic preparations. Photochemical half life of curcumin was in the minutes range. Spectrophotometric data indicate that Pluronic aggregates most likely solubilize curcumin through hydrophobic interactions, although hydrogen-bonding may also be involved.

Effect of Pressure-Induced Changes in the Ionization Equilibria of Buffers on Inactivation of Escherichia coli and Staphylococcus aureus by High Hydrostatic Pressure

PubMed Central

Gayán, Elisa; Condón, Santiago; Álvarez, Ignacio; Nabakabaya, Maria

2013-01-01

Survival rates of Escherichia coli and Staphylococcus aureus after high-pressure treatment in buffers that had large or small reaction volumes (ΔV°), and which therefore underwent large or small changes in pH under pressure, were compared. At a low buffer concentration of 0.005 M, survival was, as expected, better in MOPS (morpholinepropanesulfonic acid), HEPES, and Tris, whose ΔV° values are approximately 5.0 to 7.0 cm3 mol−1, than in phosphate or dimethyl glutarate (DMG), whose ΔV° values are about −25 cm3 mol−1. However, at a concentration of 0.1 M, survival was unexpectedly better in phosphate and DMG than in MOPS, HEPES, or Tris. This was because the baroprotective effect of phosphate and DMG increased much more rapidly with increasing concentration than it did with MOPS, HEPES, or Tris. Further comparisons of survival in solutions of salts expected to cause large electrostriction effects (Na2SO4 and CaCl2) and those causing lower electrostriction (NaCl and KCl) were made. The salts with divalent ions were protective at much lower concentrations than salts with monovalent ions. Buffers and salts both protected against transient membrane disruption in E. coli, but the molar concentrations necessary for membrane protection were much lower for phosphate and Na2SO4 than for HEPES and NaCl. Possible protective mechanisms discussed include effects of electrolytes on water compressibility and kosmotropic and specific ion effects. The results of this systematic study will be of considerable practical significance in studies of pressure inactivation of microbes under defined conditions but also raise important fundamental questions regarding the mechanisms of baroprotection by ionic solutes. PMID:23624471

Electrochemical Behavior Assessment of As-Cast Mg-Y-RE-Zr Alloy in Phosphate Buffer Solutions (X Na3PO4 + Y Na2HPO4) Using Electrochemical Impedance Spectroscopy and Mott-Schottky Techniques

NASA Astrophysics Data System (ADS)

Fattah-alhosseini, Arash; Asgari, Hamed

2018-05-01

In the present study, electrochemical behavior of as-cast Mg-Y-RE-Zr alloy (RE: rare-earth alloying elements) was investigated using electrochemical tests in phosphate buffer solutions (X Na3PO4 + Y Na2HPO4). X-ray diffraction techniques and Scanning electron microscopy equipped with energy dispersive x-ray spectroscopy were used to investigate the microstructure and phases of the experimental alloy. Different electrochemical tests such as potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS) and Mott-Schottky (M-S) analysis were carried out in order to study the electrochemical behavior of the experimental alloy in phosphate buffer solutions. The PDP curves and EIS measurements indicated that the passive behavior of the as-cast Mg-Y-RE-Zr alloy in phosphate buffer solutions was weakened by an increase in the pH, which is related to formation of an imperfect and less protective passive layer on the alloy surface. The presence of the insoluble zirconium particles along with high number of intermetallic phases of RE elements mainly Mg24Y5 in the magnesium matrix can deteriorate the corrosion performance of the alloy by disrupting the protective passive layer that is formed at pH values over 11. These insoluble zirconium particles embedded in the matrix can detrimentally influence the passivation. The M-S analysis revealed that the formed passive layers on Mg-Y-RE-Zr alloy behaved as an n-type semiconductor. An increase in donor concentration accompanying solutions of higher alkalinity is thought to result in the formation of a less resistive passive layer.

Comparing the acidities of aqueous, frozen, and freeze-dried phosphate buffers: Is there a "pH memory" effect?

PubMed

Vetráková, Ľubica; Vykoukal, Vít; Heger, Dominik

2017-09-15

The concept of "pH memory" has been established in the literature for the correlation between the pH of a pre-lyophilization solution and the ionization state of freeze-dried powder (lyophile). In this paper, the concept of "pH memory" is explored for the system of an aqueous solution, a frozen solution, and a lyophile. Sodium and potassium phosphate buffers in the pH range of 5-9 were frozen and lyophilized with sulfonephthalein indicators as acidity probes, and their Hammett acidity functions were compared to the initial pH of the aqueous solution. The results show that the acidities of the lyophiles are somewhat changed compared to the initial pHs, but the acidities in the frozen state differ more substantially. The Hammett acidity functions of the frozen buffers were found to be markedly dissimilar from the initial pH, especially in the sodium phosphate frozen at 233K, where an increase in the initial pH led to a decrease in the Hammett acidity function of the frozen state at a certain pH range. The large acidification observed after freezing the sodium phosphate buffer was not detected in the lyophiles after the sample had been dried; the phenomenon is explained considering the formed crystals analyzed by X-ray powder diffraction. The results suggest that monitoring the final acidity of a lyophile is not sufficient to predict all the acidity changes throughout the whole lyophilization process. The importance of well-controlled freezing and lyophilization conditions follows from the results of the research. Copyright © 2017 Elsevier B.V. All rights reserved.

Quantification of the internal resistance distribution of microbial fuel cells.

PubMed

Fan, Yanzhen; Sharbrough, Evan; Liu, Hong

2008-11-01

Identifying the limiting factors in a microbial fuel cell (MFC) system requires qualifying the contribution of each component of an MFC to internal resistance. In this study, a new method was developed to calculate the internal resistance distribution of an MFC. Experiments were conducted to identify the limiting factors in single-chamber MFCs by varying the anode surface areas, cathode surface areas, and phosphate buffer concentrations. For the MFCs with equally sized electrodes (7 cm2) and 200 mM phosphate buffer, the anode contributed just 5.4% of the internal resistance, while the cathode and the electrolyte each contributed 47.3%, indicating that the anode was not the limiting factor in power generation. The limitation of the cathode was further revealed by the 780% higher area-specific resistance (284.4 omega cm2) than the 32.3 omega cm2 of the anode. The electrolyte limitation was also evidenced by the greatly increased contribution of electrolyte in internal resistance from 47.3 to 78.2% when the concentration of phosphate buffer was decreased from 200 to 50 mM. An anodic power density of 6860 mW/m2 was achieved at a current density of 2.62 mA/cm2 using the MFCs with an anode/cathode area ratio of 1/14 and 200 mM phosphate buffer. The method was also successfully applied to analyze the internal resistance distribution of the two chamber MFCs from a previously reported study. The comparison of the internal resistances of the two air cathode systems indicates that the much lower resistances, including anode, cathode, and membrane resistances, contributed to the much better performance of the single-chamber MFCs than the two-chamber system.

In-vitro and in-vivo study of amorphous spironolactone prepared by adsorption method using supercritical CO2.

PubMed

Jiang, Qikun; Li, Yuanyuan; Fu, Qiang; Geng, Yajie; Zhao, Juanhang; Ma, Panqin; Zhang, Tianhong

2015-02-01

The aim of this study was to improve the oral bioavailability of spironolactone (SP). SP was adsorbed on the fumed silica using supercritical CO2 (scCO2) technology and further compressed into tablets. The morphology was observed by scanning electron microscopy (SEM), and the crystalline form was investigated by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). The dissolution test was performed in water, 0.1 M HCl solution, pH 4.5 acetate buffers and pH 6.8 phosphate buffers using the paddle method. The pharmacokinetics was undertaken in six dogs in a crossover fashion. SP was successfully prepared into tablets and presented in amorphous state. SP-silica scCO2 tablets displayed higher dissolution profiles than SP-silica physical mixtures tablets in different media. The AUC0-t and Cmax of SP-silica supercritical CO2 was 1.61- and 1.52-fold greater than those of SP-silica physical mixtures (p < 0.05), respectively. It is a promising method in improving dissolution and bioavailability by adsorbing SP, a poorly soluble drug, on the fumed silica using rapid expansion of supercritical solutions.

Optimizing Fungal DNA Extraction Methods from Aerosol Filters

NASA Astrophysics Data System (ADS)

Jimenez, G.; Mescioglu, E.; Paytan, A.

2016-12-01

Fungi and fungal spores can be picked up from terrestrial ecosystems, transported long distances, and deposited into marine ecosystems. It is important to study dust-borne fungal communities, because they can stay viable and effect the ambient microbial populations, which are key players in biogeochemical cycles. One of the challenges of studying dust-borne fungal populations is that aerosol samples contain low biomass, making extracting good quality DNA very difficult. The aim of this project was to increase DNA yield by optimizing DNA extraction methods. We tested aerosol samples collected from Haifa, Israel (polycarbonate filter), Monterey Bay, CA (quartz filter) and Bermuda (quartz filter). Using the Qiagen DNeasy Plant Kit, we tested the effect of altering bead beating times and incubation times, adding three freeze and thaw steps, initially washing the filters with buffers for various lengths of time before using the kit, and adding a step with 30 minutes of sonication in 65C water. Adding three freeze/thaw steps, adding a sonication step, washing with a phosphate buffered saline overnight, and increasing incubation time to two hours, in that order, resulted in the highest increase in DNA for samples from Israel (polycarbonate). DNA yield of samples from Monterey (quart filter) increased about 5 times when washing with buffers overnight (phosphate buffered saline and potassium phophate buffer), adding a sonication step, and adding three freeze and thaw steps. Samples collected in Bermuda (quartz filter) had the highest increase in DNA yield from increasing incubation to 2 hours, increasing bead beating time to 6 minutes, and washing with buffers overnight (phosphate buffered saline and potassium phophate buffer). Our results show that DNA yield can be increased by altering various steps of the Qiagen DNeasy Plant Kit protocol, but different types of filters collected at different sites respond differently to alterations. These results can be used as preliminary results to continue developing fungi DNA extraction methods. Developing these methods will be important as dust storms are predicted to increase due to increased draughts and anthropogenic activity, and the fungal communities of these dust-storms are currently relatively understudied.

Sensitive and fast detection of fructose in complex media via symmetry breaking and signal amplification using surface-enhanced Raman spectroscopy.

PubMed

Sun, Fang; Bai, Tao; Zhang, Lei; Ella-Menye, Jean-Rene; Liu, Sijun; Nowinski, Ann K; Jiang, Shaoyi; Yu, Qiuming

2014-03-04

A new strategy is proposed to sensitively and rapidly detect analytes with weak Raman signals in complex media using surface-enhanced Raman spectroscopy (SERS) via detecting the SERS signal changes of the immobilized probe molecules on SERS-active substrates upon binding of the analytes. In this work, 4-mercaptophenylboronic acid (4-MPBA) was selected as the probe molecule which was immobilized on the gold surface of a quasi-three-dimensional plasmonic nanostructure array (Q3D-PNA) SERS substrate to detect fructose. The molecule of 4-MPBA possesses three key functions: molecule recognition and reversible binding of the analyte via the boronic acid group, amplification of SERS signals by the phenyl group and thus shielding of the background noise of complex media, and immobilization on the surface of SERS-active substrates via the thiol group. Most importantly, the symmetry breaking of the 4-MPBA molecule upon fructose binding leads to the change of area ratio between totally symmetric 8a ring mode and nontotally symmetric 8b ring mode, which enables the detection. The detection curves were obtained in phosphate-buffered saline (PBS) and in undiluted artificial urine at clinically relevant concentrations, and the limit of detection of 0.05 mM was achieved.

Determination of tramadol hydrochloride in ampoule dosage forms by using UV spectrophotometric and HPLC-DAD methods in methanol and water media.

PubMed

Küçük, Aysel; Kadioğlu, Yücel

2005-02-01

Two newly developed simple and sensitive methods for determination of tramadol hydrochloride in ampoule dosage forms were described and validated. Measurements for spectrophotometric method were performed using UV-Vis Spectrophotometer in ranges of 200-400 nm. The solutions of standard and the samples were prepared in methanol and water media and the UV absorption spectrums of tramadol were monitored with maximum absorptions at 275 and 271 nm for both mediums, respectively. The standard calibration curves of tramadol were constructed by plotting absorbance vs. concentration in the concentration range with the final dilution of 10-100 microg ml-1. Reversed phase chromatography for HPLC method was conducted using a Phenomenex Bondclone C18 column with an isocratic mobile phase consisting of 25% acetonitrile in 75% 0.01 M phosphate buffer (pH 3). The effluent was monitored on a DAD detector at 218 nm. Linear response (r>0.99) was observed over the range of 0.5-40 microg ml-1 for methanol and water and run on six different occasions. The methods were applied successfully to pharmaceutical ampoule forms, but also for comparison in two different solvent media. Besides, it was completely validated and proven to be rugged.

Vehicle influence on permeation through intact and compromised skin.

PubMed

Gujjar, Meera; Banga, Ajay K

2014-09-10

The purpose of this study was to compare the transdermal permeation of a model compound, diclofenac diethylamine, from a hydrophilic and lipophilic vehicle across in vitro models simulating compromised skin. Mineral oil served as a lipophilic vehicle while 10mM phosphate buffered saline served as a hydrophilic vehicle. Compromised skin was simulated by tape stripping, delipidization, or microneedle application and compared with intact skin as a control. Transepidermal water loss was measured to assess barrier function. Skin compromised with tape stripping and delipidization significantly (p<0.05) increased permeation of diclofenac diethylamine compared to intact and microneedle treated skin with phosphate buffered saline vehicle. A similar trend in permeation was observed with mineral oil as the vehicle. For both vehicles, permeation across skin increased in the same order and correlated with degree of barrier impairment as indicated by transepidermal water loss values: intact

Physical and chemical properties of pyropheophorbide-a methyl ester in ethanol, phosphate buffer and aqueous dispersion of small unilamellar dimyristoyl-L-alpha-phosphatidylcholine vesicles.

PubMed

Delanaye, Lisiane; Bahri, Mohamed Ali; Tfibel, Francis; Fontaine-Aupart, Marie-Pierre; Mouithys-Mickalad, Ange; Heine, Bélinda; Piette, Jacques; Hoebeke, Maryse

2006-03-01

The aggregation process of pyropheophorbide-a methyl ester (PPME), a second-generation photosensitizer, was investigated in various solvents. Absorption and fluorescence spectra showed that the photosensitizer was under a monomeric form in ethanol as well as in dimyristoyl-L-alpha-phosphatidylcholine liposomes while it was strongly aggregated in phosphate buffer. A quantitative determination of reactive oxygen species production by PPME in these solvents has been undertaken by electron spin resonance associated with spin trapping technique and absorption spectroscopy. In phosphate buffer, both electron spin resonance and absorption measurements led to the conclusion that singlet oxygen production was not detectable while hydroxyl radical production was very weak. In liposomes and ethanol, singlet oxygen and hydroxyl radical production increased highly; the singlet oxygen quantum yield was determined to be 0.2 in ethanol and 0.13 in liposomes. The hydroxyl radical production origin was also investigated. Singlet oxygen was formed from PPME triplet state deactivation in the presence of oxygen. Indeed, the triplet state formation quantum yield of PPME was found to be about 0.23 in ethanol, 0.15 in liposomes (too small to be measured in PBS).

Electrospun PVA/Bentonite Nanocomposites Mats for Drug Delivery

PubMed Central

Ferrández-Rives, Mariola; Gómez Ribelles, José Luis

2017-01-01

Electrospun mats and films of polyvinyl alcohol (PVA) hydrogel are produced for drug delivery. To provide mechanical consistency to the gel a reinforcement by nanoclays is introduced in the polymer matrix. Four different suspensions of nanoparticles in the polymer solution are prepared in an adequate solvent. These suspensions are subjected to an electrospinning process to produce the nanofiber mat, while films are produced by casting. The influence of the process parameters over the nanofibers microstructure is analyzed by scanning electron microscopy (SEM). The effectiveness of nanoclay encapsulation in the nanocomposites is tested by a thermogravimetric analysis. A crosslinking reaction in solution is carried out to prevent the dissolution of the nanocomposites in aqueous media. A model protein (bovine serum albumin, BSA) is absorbed in the nanocomposites to characterize the release kinetics in phosphate-buffered saline (PBS). PMID:29261123

A Prototype Antifungal Contact Lens

PubMed Central

Ciolino, Joseph B.; Hudson, Sarah P.; Mobbs, Ashley N.; Hoare, Todd R.; Iwata, Naomi G.; Fink, Gerald R.

2011-01-01

Purpose. To design a contact lens to treat and prevent fungal ocular infections. Methods. Curved contact lenses were created by encapsulating econazole-impregnated poly(lactic-co-glycolic) acid (PLGA) films in poly(hydroxyethyl methacrylate) (pHEMA) by ultraviolet photopolymerization. Release studies were conducted in phosphate-buffered saline at 37°C with continuous shaking. The contact lenses and their release media were tested in an antifungal assay against Candida albicans. Cross sections of the pre- and postrelease contact lenses were characterized by scanning electron microscopy and by Raman spectroscopy. Results. Econazole-eluting contact lenses provided extended antifungal activity against Candida albicans fungi. Fungicidal activity varied in duration and effectiveness depending on the mass of the econazole-PLGA film encapsulated in the contact lens. Conclusions. An econazole-eluting contact lens could be used as a treatment for fungal ocular infections. PMID:21527380

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (GdSingapore) and three deficient variants.

PubMed

Saha, N; Hong, S H; Wong, H A; Jeyaseelan, K; Tay, J S

1991-12-01

Biochemical characteristics of one non-deficient fast G6PD variant (GdSingapore) and six different deficient variants (three new, two Mahidol, one each of Indonesian and Mediterranean) were studied among the Malays of Singapore. The GdSingapore variant had normal enzyme activity (82%) and fast electrophoretic mobilities (140% in TEB buffer, 160% in phosphate and 140% in Tris-HCl buffer systems respectively). This variant is further characterized by normal Km for G6P; utilization of analogues (Gal6P, 2dG6P; dAmNADP), heat stability and pH optimum. The other six deficient G6PD variants had normal electrophoretic mobility in TEB buffer with enzyme activities ranging from 1 to 12% of GdB+. The biochemical characteristics identity them to be 2 Mahidol, 1 Indonesian and 1 Mediterranean variants and three new deficient variants.

Analysis of three variables in sampling solutions used to assay bacteria of hands: type of solution, use of antiseptic neutralizers, and solution temperature.

PubMed Central

Larson, E L; Strom, M S; Evans, C A

1980-01-01

Tests were performed using the sterile bag technique to determine the effects of type of sampling solution, use of antiseptic neutralizers, and solution temperature on the detection and quantitation of bacteria on hands. Using paired hand cultures, three sampling solutions were compared: quarter-strength Ringer solution, a phosphate buffer containing Triton X-100, and the same buffer containing antiseptic neutralizers. The phosphate buffer containing Triton X-100 was significantly better than quarter-strength Ringer solution in mean bacterial yield; the neutralizer-containing sampling solution was slightly better than Triton X-100-containing solution, although differences were not significant at the P = 0.05 level. Temperature (6 or 23 degrees C) of the sampling solution showed no consistent effect on bacterial yield from hands tested with the fluid containing neutralizers. PMID:7012171

The effect of the type of HA on the degradation of PLGA/HA composites.

PubMed

Naik, Ashutosh; Shepherd, David V; Shepherd, Jennifer H; Best, Serena M; Cameron, Ruth E

2017-01-01

The aim of this study is to explore the importance of the potentially competing effects of buffering effects of the calcium phosphate filler and particle-mediated water sorption on the degradation products of poly(d,l lactide-co-glycolide (50:50))(PLGA)/hydroxyapatite(HA) composites. Further the influence of type of HA on the mechanical properties of the composites was investigated. Phase pure HA was synthesised via a reaction between aqueous solutions of calcium hydroxide and orthophosphoric acid. The powder produced was either used as produced (uncalcined) or calcined in air or calcined in a humidified argon atmosphere. An in-vitro degradation study was carried out in phosphate buffered saline (PBS). The results obtained indicated that the degradation rate of the composite might be better understood if both the buffering effects and the rate of water sorption by the composites are considered. Copyright © 2016 Elsevier B.V. All rights reserved.

Polymer coated liposomes for dental drug delivery--interactions with parotid saliva and dental enamel.

PubMed

Nguyen, S; Hiorth, M; Rykke, M; Smistad, G

2013-09-27

The interactions between pectin coated liposomes and parotid saliva and dental enamel were studied to investigate their potential to mimic the protective biofilm formed naturally on tooth surfaces. Different pectin coated liposomes with respect to pectin type (LM-, HM- and AM-pectin) and concentration (0.05% and 0.2%) were prepared. Interactions between the pectin coated liposomes and parotid saliva were studied by turbidimetry and imaging by atomic force microscopy. The liposomes were adsorbed to hydroxyapatite (HA) and human dental enamel using phosphate buffer and parotid saliva as adsorption media. A continuous flow was imposed on the enamel surfaces for various time intervals to examine their retention on the dental enamel. The results were compared to uncoated, charged liposomes. No aggregation tendencies for the pectin coated liposomes and parotid saliva were revealed. This makes them promising as drug delivery systems to be used in the oral cavity. In phosphate buffer the adsorption to HA of pectin coated liposomes was significantly lower than the negative liposomes. The difference diminished in parotid saliva. Positive liposomes adsorbed better to the dental enamel than the pectin coated liposomes. However, when subjected to flow for 1h, no significant differences in the retention levels on the enamel were found between the formulations. For all formulations, more than 40% of the liposomes still remained on the enamel surfaces. At time point 20 min the retention of HM-pectin coated and positive liposomes were significantly higher. It was concluded that pectin coated liposomes can adsorb to HA as well as to the dental enamel. Their ability to retain on the enamel surfaces promotes the concept of using them as protective structures for the teeth. Copyright © 2013 Elsevier B.V. All rights reserved.

Phytosome-hyaluronic acid systems for ocular delivery of L-carnosine

PubMed Central

Abdelkader, Hamdy; Longman, Michael R; Alany, Raid G; Pierscionek, Barbara

2016-01-01

This study reports on L-carnosine phytosomes as an alternative for the prodrug N-acetyl-L-carnosine as a novel delivery system to the lens. L-carnosine was loaded into lipid-based phytosomes and hyaluronic acid (HA)-dispersed phytosomes. L-carnosine-phospholipid complexes (PC) of different molar ratios, 1:1 and 1:2, were prepared by the solvent evaporation method. These complexes were characterized with thermal and spectral analyses. PC were dispersed in either phosphate buffered saline pH 7.4 or HA (0.1% w/v) in phosphate buffered saline to form phytosomes PC1:1, PC1:2, and PC1:2 HA, respectively. These phytosomal formulations were studied for size, zeta potential, morphology, contact angle, spreading coefficient, viscosity, ex vivo transcorneal permeation, and cytotoxicity using primary human corneal cells. L-carnosine-phospholipid formed a complex at a 1:2 molar ratio and phytosomes were in the size range of 380–450 nm, polydispersity index of 0.12–0.2. The viscosity of PC1:2 HA increased by 2.4 to 5-fold compared with HA solution and PC 1:2, respectively; significantly lower surface tension, contact angle, and greater spreading ability for phytosomes were also recorded. Ex vivo transcorneal permeation parameters showed significantly controlled corneal permeation of L-carnosine with the novel carrier systems without any significant impact on primary human corneal cell viability. Ex vivo porcine lenses incubated in high sugar media without and with L-carnosine showed concentration-dependent marked inhibition of lens brunescence indicative of the potential for delaying changes that underlie cataractogenesis that may be linked to diabetic processes. PMID:27366062

Effect of platelet activating factor with and without receptor antagonist (WEB2170) on morphology of isolated cochlear outer hair cells.

PubMed

Jung, Timothy T K; John, Earnest O; Park, Seong Kook; Park, Yong Soo; Rhee, Chong-Ku

2004-02-01

Platelet activating factor (PAF), generated from biologically active phospholipids, has been implicated as a potent inflammatory mediator and has been shown to be involved in many pathological processes, especially in inflammation and allergy. It has been suspected that PAF may be one of the inflammatory mediators in middle ear effusion that can induce sensorineural hearing loss, as observed in chronic otitis media. The PAF receptor antagonist WEB2170 has been studied extensively, and its inhibitory effects against various PAF actions are well proven in otologic systems. The purpose of our study was to determine the effect of superfusion of PAF and WEB2170 on morphological changes in isolated cochlear outer hair cells (OHCs). Isolated OHCs from adult chinchilla cochleas were exposed to albumin-phosphate-buffered saline solution (1 mg/mL), WEB2170 (5 mg/30 mL), PAF (1 micromol/L), or both PAF (I micromol/L) and WEB2170 (5 mg/30 mL). All experiments were performed at an osmolality of 305 +/- 5 mOsm at room temperature for 30 minutes. The cells were observed with an inverted microscope; the images were stored and analyzed on the Image Pro-Plus program. The OHCs exposed to control albumin-phosphate-buffered saline solution or to WEB2170 did not show any significant change in cell shape or length. The cells exposed to 1 micromol/L of PAF showed ballooning and significant shortening of the mean cell length in 15 to 20 minutes. These morphological changes in OHCs can be prevented by pretreating OHCs with WEB2170. This study demonstrated that exposure to PAF causes morphological changes in isolated OHCs that can be prevented by the PAF receptor antagonist WEB2170.

Kinetic and thermodynamic parameters for thermal denaturation of ovine milk lactoferrin determined by its loss of immunoreactivity.

PubMed

Navarro, F; Harouna, S; Calvo, M; Pérez, M D; Sánchez, L

2015-07-01

Lactoferrin is a protein with important biological functions that can be obtained from milk and by-products derived from the dairy industry, such as whey. Although bovine lactoferrin has been extensively studied, ovine lactoferrin is not quite as well known. In the present study, the effect of several heat treatments in 3 different media, over a temperature range from 66 to 75°C, has been studied on lactoferrin isolated from sheep milk. Denaturation of lactoferrin was determined by measuring its immunoreactivity with specific polyclonal antibodies. Kinetic and thermodynamic parameters obtained indicate that lactoferrin denatures by heat more rapidly in whey than in phosphate buffer or milk. The value of activation energy found for the denaturation process of lactoferrin when treated in whey is higher (390kJ/mol) than that obtained in milk (194kJ/mol) or phosphate buffer (179kJ/mol). This indicates that a great amount of energy is necessary to start denaturation of ovine lactoferrin, probably due to the interaction of this protein with other whey proteins. The changes in the hydrophobicity of lactoferrin after heat treatments were determined by fluorescence measurement using acrylamide. The decrease in the hydrophobicity constant was very small for the treatments from 66 to 75°C, up to 20min, which indicates that lactoferrin conformation did not experienced a great change. The results obtained in this study permit the prediction of behavior of ovine lactoferrin under several heat treatments and show that high-temperature, short-time pasteurization (72°C, 15 s) does not cause loss of its immunoreactivity and, consequently, would not affect its conformation and biological activity. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

New insights into the antioxidant activity of hydroxycinnamic and hydroxybenzoic systems: spectroscopic, electrochemistry, and cellular studies.

PubMed

Mura, F; Silva, T; Castro, C; Borges, F; Zuñiga, M C; Morales, J; Olea-Azar, C

2014-12-01

A series hydroxycinnamic and gallic acids and their derivatives were studied with the aim of evaluating their in vitro antioxidant properties both in homogeneous and in cellular systems. It was concluded from the oxygen radical absorbance capacity-fluorescein (ORAC-FL), 1,1-diphenyl-2-picrylhydrazyl (DPPH), and cyclic voltammetry data that some compounds exhibit remarkable antioxidant properties. In general, in homogeneous media (DPPH assay), galloyl-based cinnamic and benzoic systems (compounds 7-11) were the most active, exhibiting the lowest oxidation potentials in both dimethyl sulfoxide (DMSO) and phosphate buffer. Yet, p-coumaric acid and its derivatives (compounds 1-3) disclosed the highest scavenging activity toward peroxyl radicals (ORAC-FL assay). Interesting structure-property- activity relationships between ORAC-FL, or DPPH radical, and redox potentials have been attained, showing that the latter parameter can be a valuable antioxidant measure. It was evidenced that redox potentials are related to the structural features of cinnamic and benzoic systems and that their activities are also dependent on the radical generated in the assay. Electron spin resonance data of the phenoxyl radicals generated both in DMSO and phosphate buffer support the assumption that radical stability is related to the type of phenolic system. Galloyl-based cinnamic and benzoic ester-type systems (compounds 9 and 11) were the most active and effective compounds in cell-based assays (51.13 ± 1.27% and 54.90 ± 3.65%, respectively). In cellular systems, hydroxycinnamic and hydroxybenzoic systems operate based on their intrinsic antioxidant outline and lipophilic properties, so the balance between these two properties is considered of the utmost importance to ensure their performance in the prevention or minimization of the effects due to free radical overproduction.

The Role of Newly Discovered Exotoxin (S Toxin) in Pseudomonas aeruginosa Infections

DTIC Science & Technology

1979-08-01

sodium or potassium phosphate 6.0-8.0 N-2-hydroxyethylpiperazine-N’-2-ethanesulfonic acid (HEPES) 6.5-8.5 tris 7.0-9.5 sodium borate 7.5-9.5 sodium...was found to be variable with respect to whether sodium or potassium phosphate buffer was used. With sodium phosphate, virtually all the enzyme...activity bound was eluted between 20-100.2M phosphate at pH 6.8. With the potassium salt, elution occurs at 400-?00mM KP04. Since very little protein was

Glucose buffer is suitable for blood group conversion with α-N acetylgalactosaminidase and α-galactosidase

PubMed Central

Gao, Hong-Wei; Li, Su-Bo; Bao, Guo-Qiang; Zhang, Xue; Li, Hui; Wang, Ying-Li; Tan, Ying-Xia; Ji, Shou-Ping; Gong, Feng

2014-01-01

Background It is well known that the buffer plays a key role in the enzymatic reaction involved in blood group conversion. In previous study, we showed that a glycine buffer is suitable for A to O or B to O blood group conversion. In this study, we investigated the use of 5% glucose and other buffers for A to O or B to O blood group conversion by α-N-acetylgalactosaminidase or α-galactosidase. Materials and methods We compared the binding ability of α-N-acetylgalactosaminidase/α-galactosidase with red blood cells (RBC) in different reaction buffers, such as normal saline, phosphate-buffered saline (PBS), a disodium hydrogen phosphate-based buffer (PCS), and 5% commercial glucose solution. The doses of enzymes necessary for the A/B to O conversion in different reaction buffers were determined and compared. The enzymes’ ability to bind to RBC was evaluated by western blotting, and routine blood typing and fluorescence activated cell sorting was used to evaluate B/A to O conversion efficiency. Results The A to O conversion efficiency in glucose buffer was similar to that in glycine buffer with the same dose (>0.06 mg/mL pRBC). B to O conversion efficiency in glucose buffer was also similar to that in glycine buffer with the same dose (>0.005 mg/mL pRBC). Most enzymes could bind with RBC in glycine or glucose buffer, but few enzymes could bind with RBC in PBS, PCS, or normal saline. Conclusion These results indicate that 5% glucose solution provides a suitable condition for enzymolysis, especially for enzymes combining with RBC. Meanwhile, the conversion efficiency of A/B to O was similar in glucose buffer and glycine buffer. Moreover, 5% glucose solution has been used for years in venous transfusion, it is safe for humans and its cost is lower. Our results do, therefore, suggest that 5% glucose solution could become a novel suitable buffer for A/B to O blood group conversion. PMID:24333060

Lethality of a Heat- and Phosphate-Catalyzed Glucose By-Product to Escherichia coli O157:H7 and Partial Protection Conferred by the rpoS Regulon

PubMed Central

Byrd, Jeffrey J.; Cheville, Ann M.; Bose, Jeffrey L.; Kaspar, Charles W.

1999-01-01

A by-product of glucose produced during sterilization (121°C, 15 lb/in2, 15 min) at neutral pH and in the presence of phosphate (i.e., phosphate-buffered saline) was bactericidal to Escherichia coli O157:H7 (ATCC 43895). Other six-carbon (fructose and galactose) and five-carbon (arabinose, ribose, and xylose) reducing sugars also produced a toxic by-product under the same conditions. Fructose and the five-carbon sugars yielded the most bactericidal activity. Glucose concentrations of 1% (wt/vol) resulted in a 99.9% decline in the CFU of stationary-phase cells per milliliter in 2 days at 25°C. An rpoS mutant (pRR10::rpoS) of strain 43895 (FRIK 816-3) was significantly (P < 0.001) more sensitive to the glucose-phosphate by-product than the parent strain, as glucose concentrations from 0.05 to 0.25% resulted in a 2- to 3-log10 reduction in CFU per milliliter in 2 days at 25°C. Likewise, log-phase cells of the wild-type strain, 43895, were significantly more sensitive (P < 0.001) to the glucose-phosphate by-product than were stationary-phase cells, which is consistent with the stability of rpoS and the regulation of rpoS-regulated genes. The bactericidal effect of the glucose-phosphate by-product was reduced when strains ATCC 43895 and FRIK 816-3 were incubated at a low temperature (4°C). Also, growth in glucose-free medium (i.e., nutrient broth) did not alleviate the sensitivity to the glucose-phosphate by-product and excludes the possibility of substrate-accelerated death as the cause of the bactericidal effect observed. The glucose-phosphate by-product was also bactericidal to Salmonella typhimurium, Shigella dysenteriae, and a Klebsiella sp. Attempts to identify the glucose-phosphate by-product were unsuccessful. These studies demonstrate the production of a glucose-phosphate by-product bactericidal to E. coli O157:H7 and the protective effects afforded by rpoS-regulated gene products. Additionally, the detection of sublethally injured bacteria may be compromised by the presence of this by-product in recovery media. PMID:10347019

Identification and root cause analysis of cell culture media precipitates in the viral deactivation treatment with high-temperature/short-time method.

PubMed

Cao, Xiaolin; Stimpfl, Gregory; Wen, Zai-Qing; Frank, Gregory; Hunter, Glenn

2013-01-01

High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the biopharmaceutical manufacturing industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating and pumping the media continuously through the preset high-temperature holding tubes to achieve a specified period of time at a specific temperature. Recently, during the evaluation and implementation of HTST method in multiple Amgen, Inc. manufacturing facilities, media precipitates were observed in the tests of HTST treatments. The media precipitates may have adverse consequences such as clogging the HTST system, altering operating conditions and compromising the efficacy of viral deactivation, and ultimately affecting the media composition and cell growth. In this study, we report the identification of the composition of media precipitates from multiple media HTST runs using combined microspectroscopic methods including Raman, Fourier transform infrared spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy. The major composition in the precipitates was determined to be metal phosphates, including calcium phosphate, magnesium phosphate, and iron (III) phosphate. Based on the composition, stoichiometry, and root-cause study of media precipitations, methods were implemented for the mitigation and prevention of the occurrence of the media precipitation. Viral contamination in cell culture media is an important issue in the biopharmaceutical manufacturing industry and may have serious consequences on product quality, efficacy, and safety. High-temperature/short-time (HTST) treatment of cell culture media is one of the proven techniques used in the industry for the prevention and mitigation of media viral contamination. With the HTST method, the formulated media is pasteurized (virus-deactivated) by heating at preset conditions. This paper provides the identification and root-cause study of the media precipitates that adversely affected the HTST process and discusses the possible solutions to mitigate the precipitation problem.

A Phos-tag-based magnetic-bead method for rapid and selective separation of phosphorylated biomolecules.

PubMed

Tsunehiro, Masaya; Meki, Yuma; Matsuoka, Kanako; Kinoshita-Kikuta, Emiko; Kinoshita, Eiji; Koike, Tohru

2013-04-15

A simple and efficient method based on magnetic-bead technology has been developed for the separation of phosphorylated and nonphosphorylated low-molecular-weight biomolecules, such as nucleotides, phosphorylated amino acids, or phosphopeptides. The phosphate-binding site on the bead is an alkoxide-bridged dinuclear zinc(II) complex with 1,3-bis(pyridin-2-ylmethylamino)propan-2-olate (Phos-tag), which is linked to a hydrophilic cross-linked agarose coating on a magnetic core particle. All steps for the phosphate-affinity separation are conducted in buffers of neutral pH with 50 μL of the magnetic beads in a 1.5-mL microtube. The entire separation protocol for phosphomonoester-type compounds, from addition to elution, requires less than 12 min per sample if the buffers and the zinc(II)-bound Phos-tag magnetic beads have been prepared in advance. The phosphate-affinity magnetic beads are reusable at least 15 times without a decrease in their phosphate-binding ability and they are stable for three months in propan-2-ol. Copyright © 2013 Elsevier B.V. All rights reserved.

Cullin 5 Expression in the Rat: Cellular and Tissue Distribution, and Changes in Response to Water Deprivation and Hemorrhagic Shock

DTIC Science & Technology

2003-02-28

of Health p53 tumor suppressor PBS phosphate buffered saline PCO2 partial pressure of carbon dioxide PO2 partial pressure of oxygen PCR...buffered saline TTBS tween-20 tris buffered saline TonEBP tonicity-response enhancer binding protein TSNRP TriService Nursing Research Program...growth and metabolism (Hochstrasser, 1995; Deshaies, 1999). Although traditionally seen as no more than a means of eliminating no longer needed

Approaching Mars-like geochemical conditions in the laboratory: omission of artificial buffers and reductants in a study of biogenic methane production on a smectite clay.

PubMed

Chastain, Brendon K; Kral, Timothy A

2010-11-01

Methanogens have not been shown to metabolize in conditions exactly analogous to those present in Mars' subsurface. In typical studies of methanogenic metabolism, nutrient-rich buffered media and reducing agents are added to the cultures in an attempt to optimize the environment for methanogen survival and growth. To study methanogens in more Mars-relevant laboratory conditions, efforts should be made to eliminate artificial media, buffers, and reducing agents from investigations of methanogenic metabolism. After preliminary work to compare methanogen viability on montmorillonite clay and JSC Mars-1 regolith simulant, a study was conducted to determine whether biological methanogenesis could occur in non-reduced, non-buffered environments containing only H(2), CO(2), montmorillonite, and the liquid fraction extracted from a montmorillonite/deionized water suspension. Biogenic methane was observed in the microenvironments despite the omission of traditional media, buffers, and reducing agents. Mean headspace methane concentration after 96 days of observation was 10.23% ± 0.64% (% vol ± SEM, n = 4). However, methane production was severely decreased with respect to reduced, buffered microenvironments (Day 28: 31.98% ± 0.19%, n = 3). Analysis of results and comparison to previous work indicate that montmorillonite clay has a strong ability to supply micronutrients necessary for methanogenic metabolism, and the liquid fraction from a montmorillonite/deionized water slurry can successfully be used as an alternative to reduced and buffered nutritive media in Mars-relevant studies of methanogenic metabolism.

The Effects of pH on the Growth and Aspect Ratio of Chicken Egg White Lysozyme Crystals Prepared in Different Buffers

NASA Technical Reports Server (NTRS)

Gibson, U. J.; Horrell, E. E.; Kou, Y.; Pusey, Marc

2000-01-01

We have measured the nucleation and aspect ratio of CEWL crystals grown by vapor diffusion in acetate, butyrate, carbonate, succinate, and phosphate buffers in a range of pH spanning the pK(sub a) of these buffers. The nucleation numbers drop off significantly in the vicinity of pK(sub a) for each of the buffers except the phosphate system, in which we used only the pH range around the second titration point(pK2). There is a concomitant increase in the sizes of the crystals. Some typical nucleation number results are shown. These data support and extend other observations. In addition, we have examined changes in aspect ratio which accompany the suppression of nucleation within each buffer system. The length of the face in the [001] direction was measured, and compared to the width of the (110) face in the [110] type directions. We find that while the aspect ratio of the crystals is affected by pH, it is dominated by a correlation with the size of the crystals. Small crystals are longer in the [0011 direction than crystals that are larger (higher pH within a buffer system). This relationship is found to hold independent of the choice of buffer. These results are consistent with those of Judge et al, who used a batch process which resulted in uniform sizing of crystals at each pH. In these experiments, we specifically avoid agitating the protein/salt buffer mixture when combining the two. This permits the formation of a range of sizes at a given pH. The results for a .05 M acetate 5% NaCl buffer are also shown. We will discuss these results in light of a growth model.

ROBUST: The ROle of BUffering capacities in STabilising coastal lagoon ecosystems

NASA Astrophysics Data System (ADS)

de Wit, Rutger; Stal, Lucas J.; Lomstein, Bente Aa.; Herbert, Rodney A.; van Gemerden, Hans; Viaroli, Pierluigi; Cecherelli, Victor-Ugo; Rodríguez-Valera, Francisco; Bartoli, Marco; Giordani, Gianmarco; Azzoni, Roberta; Schaub, Bart; Welsh, David T.; Donnelly, Andrew; Cifuentes, Ana; Antón, Josefa; Finster, Kai; Nielsen, Lise B.; Pedersen, Anne-Grethe Underlien; Neubauer, Anne Turi; Colangelo, Marina A.; Heijs, Sander K.

2001-12-01

"Buffer capacities" has been defined in ecology as a holistic concept (e.g., Integration of Ecosystem Theories: A Pattern, second ed. Kluwer, Dordrecht, 1997, 388pp), but we show that it can also be worked out in mechanistic studies. Our mechanistic approach highlights that "buffering capacities" can be depleted progressively, and, therefore, we make a distinction between current and potential "buffering capacities". We have applied this concept to understand the limited "local stability" in seagrass ecosystems and their vulnerability towards structural changes into macro-algal dominated communities. We explored the following processes and studied how they confer buffering capacities to the seagrass ecosystem: (i) net autotrophy is persistent in Zostera noltii meadows where plant assimilation acts as a sink for nutrients, this contrasted with the Ulva system that shifted back and forth between net autotrophy and net heterotrophy; (ii) the Z. noltii ecosystem possesses a certain albeit rather limited capacity to modify the balance between nitrogen fixation and denitrification, i.e., it was found that in situ nitrogen fixation always exceeded denitrification; (iii) the nitrogen demand of organoheterotrophic bacteria in the sediment results in nitrogen retention of N in the sediment and hence a buffer against release of nitrogen compounds from sediments, (iv) habitat diversification in seagrass meadows provides shelter for meiofauna and hence buffering against adverse conditions, (v) sedimentary iron provides a buffer against noxious sulfide (note: bacterial sulfide production is enhanced in anoxic sediment niches by increased organic matter loading). On the other hand, in the coastal system we studied, sedimentary iron appears less important as a redox-coupled buffer system against phosphate loading. This is because most inorganic phosphate is bound to calcium rather than to iron. In addition, our studies have highlighted the importance of plant-microbe interactions in the seagrass meadows.

Plaquing procedure for infectious hematopoietic necrosis virus

USGS Publications Warehouse

Burke, J.A.; Mulcahy, D.

1980-01-01

A single overlay plaque assay was designed and evaluated for infectious hematopoietic necrosis virus. Epithelioma papillosum carpio cells were grown in normal atmosphere with tris(hydroxymethyl)aminomethane- or HEPES (N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid)-buffered media. Plaques were larger and formed more quickly on 1- to 3-day-old cell monolayers than on older monolayers. Cell culture medium with a 10% addition of fetal calf serum (MEM 10) or without serum (MEM 0) were the most efficient virus diluents. Dilution with phosphate-buffered saline, saline, normal broth, or deionized water reduced plaque numbers. Variations in the pH (7.0 to 8.0) of a MEM 0 diluent did not affect plaque numbers. Increasing the volume of viral inoculum above 0.15 ml (15- by 60-mm plate) decreased plaquing efficiency. Significantly more plaques occurred under gum tragacanth and methylcellulose than under agar or agarose overlays. Varying the pH (6.8 to 7.4) of methylcellulose overlays did not significantly change plaque numbers. More plaques formed under the thicker overlays of both methylcellulose and gum tragacanth. Tris(hydroxymethyl)aminomethane and HEPES performed equally well, buffering either medium or overlay. Plaque numbers were reduced when cells were rinsed after virus adsorption or less than 1 h was allowed for adsorption. Variation in adsorption time between 60 and 180 min did not change plaque numbers. The mean plaque formation time was 7 days at 16 degrees C. The viral dose response was linear when the standardized assay was used.

Influence of calcium, iron and pH on phosphate availability for microbial mineralization of organic chemicals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Robertson, B.K.; Alexander, M.

1992-01-01

A study was conducted to determine some of the factors affecting the P requirement for the biodegradation of p-nitrophenol, phenol, and glucose by Pseudomonas and Corynebacterium strains. Mineralization of glucose was rapid and the Pseudomonas sp. grew extensively in solutions with 5 and 10 mM phosphate, but the rate and extent of degradation were low and the bacterial population never became abundant in media with 0.2 mM phosphate. Similar results were obtained with the Corynebacterium sp. growing in media containing p-nitrophenol or phenol and in solutions with a purified phosphate salt. The extent of growth of the Corynebacterium sp. wasmore » reduced with 2 or 10 mM phosphate in media containing high Fe concentrations. Ca at 5 mM but not 0.5 mM inhibited p-nitrophenol mineralization by the Corynebacterium sp. with phosphate concentrations from 0.2 to 5.0 mM. Phenol mineralization by the Pseudomonas sp. in medium with 0.2 mM phosphate was rapid at pH 5.2, but the bacteria had little or no activity at pH 8.0. In contrast, the activity was greater at pH 8.0 than at pH 5.2 when the culture contained 10 mM phosphate. These effects of pH were similar in media with 5 mM Ca or no added Ca. The authors conclude that the effect of P on bacterial degradation can be influenced by the pH and the concentrations of Fe and Ca.« less

Effect of degree of esterification of pectin and calcium amount on drug release from pectin-based matrix tablets.

PubMed

Sungthongjeen, Srisagul; Sriamornsak, Pornsak; Pitaksuteepong, Tasana; Somsiri, Atawit; Puttipipatkhachorn, Satit

2004-02-12

The aim of this work was to assess the effect of 2 formulation variables, the pectin type (with different degrees of esterification [DEs]) and the amount of calcium, on drug release from pectin-based matrix tablets. Pectin matrix tablets were prepared by blending indomethacin (a model drug), pectin powder, and various amounts of calcium acetate and then tableting by automatic hydraulic press machine. Differential scanning calorimetry, powder x-ray diffraction, and Fourier transformed-infrared spectroscopy studies of the compressed tablets revealed no drug-polymer interaction and the existence of drug with low crystallinity. The in-vitro release studies in phosphate buffer (United States Pharmacopeia) and tris buffer indicated that the lower the DE, the greater the time for 50% of drug release (T50). This finding is probably because of the increased binding capacity of pectin to calcium. However, when the calcium was excluded, the pectins with different DEs showed similar release pattern with insignificant difference of T50. When the amount of calcium acetate was increased from 0 to 12 mg/tablet, the drug release was significantly slower. However, a large amount of added calcium (ie, 24 mg/tablet) produced greater drug release because of the partial disintegration of tablets. The results were more pronounced in phosphate buffer, where the phosphate ions induced the precipitation of calcium phosphate. In conclusion, both pectin type and added calcium affect the drug release from the pectin-based matrix tablets.

Biaxially textured composite substrates

DOEpatents

Groves, James R.; Foltyn, Stephen R.; Arendt, Paul N.

2005-04-26

An article including a substrate, a layer of a metal phosphate material such as an aluminum phosphate material upon the surface of the substrate, and a layer of an oriented cubic oxide material having a rock-salt-like structure upon the metal phosphate material layer is provided together with additional layers such as a HTS top-layer of YBCO directly upon a layer of a buffer material such as a SrTi.sub.x Ru.sub.1-x O.sub.3 layer.

Comparative evaluation of the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol-containing chewing gum on salivary flow rate, pH and buffering capacity in children: An in vivo study.

PubMed

Hegde, Rahul J; Thakkar, Janhavi B

2017-01-01

This study aimed to compare and evaluate the changes in the salivary flow rate, pH, and buffering capacity before and after chewing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and xylitol-containing chewing gums in children. Sixty children aged between 8 and 12 years were selected for the study. They were randomly divided into Group 1 (CPP-ACP chewing gum) and Group 2 (xylitol-containing chewing gum) comprising thirty children each. Unstimulated and stimulated saliva samples at 15 and 30 min interval were collected from all children. All the saliva samples were estimated for salivary flow rate, pH, and buffering capacity. Significant increase in salivary flow rate, pH, and buffering capacity from baseline to immediately after spitting the chewing gum was found in both the study groups. No significant difference was found between the two study groups with respect to salivary flow rate and pH. Intergroup comparison indicated a significant increase in salivary buffer capacity in Group 1 when compared to Group 2. Chewing gums containing CPP-ACP and xylitol can significantly increase the physiochemical properties of saliva. These physiochemical properties of saliva have a definite relation with caries activity in children.

Effect of Phosphate-Buffered Solution Corrosion on the Ratcheting Fatigue Behavior of a Duplex Mg-Li-Al Alloy

NASA Astrophysics Data System (ADS)

Yuan, Xin; Yu, Dunji; Gao, Li-Lan; Gao, Hong

2016-05-01

This work reports the uniaxial ratcheting and fatigue behavior of a duplex Mg-Li-Al alloy under the influence of phosphate-buffered solution corrosion. Microstructural observations reveal pitting and filament corrosion defects, which impair the load-bearing capacity of the alloy and cause stress concentration, thus leading to an accelerated accumulation of ratcheting strain and shortened fatigue life under the same nominal loading conditions. Comparing Smith model, Smith-Watson-Topper model, and Paul-Sivaprasad-Dhar model, a ratcheting fatigue life prediction model based on the Broberg damage rule and the Paul-Sivaprasad-Dhar model was proposed, and the model yielded a superior prediction for the studied magnesium alloy.

Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli.

PubMed

Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea

2014-03-19

Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity inorganic phosphate transport (Pit) system in E. coli copper tolerance. PolyP levels were modulated by the media phosphate concentration and/or using mutants in polyP metabolism. Stationary phase wild-type cells grown in high phosphate medium were significantly more tolerant to copper than those grown in sufficient phosphate medium. Copper addition to tolerant cells induced polyP degradation by PPX (an exopolyphosphatase), phosphate efflux and membrane polarization. ppk-ppx- (unable to synthesize/degrade polyP), ppx- (unable to degrade polyP) and Pit system mutants were highly sensitive to metal even in high phosphate media. In exponential phase, CopA and polyP-Pit system would act simultaneously to detoxify the metal or one could be sufficient to safeguard the absence of the other. Our results support a mechanism for copper detoxification in exponential and stationary phases of E. coli, involving Pit system and degradation of polyP. Data reflect the importance of the environmental phosphate concentration in the regulation of the microbial physiological state.

Osmotic characteristics and fertility of murine spermatozoa collected in different solutions.

PubMed

Si, Wei; Men, Hongsheng; Benson, James D; Critser, John K

2009-02-01

Osmotic stress is an important factor that can result in cell damage during cryopreservation. Before ejaculation or collection for cryopreservation, murine spermatozoa are stored in epididymal fluid, a physiologically hyperosmotic environment (approximately 415 mmol/kg). The objectives of this study were to determine the osmotic tolerance limits of sperm motion parameters of ICR and C57BL/6 mouse spermatozoa collected in isosmotic (290 mmol/kg) and hyperosmotic (415 mmol/kg) media, and the effect of the osmolality of sperm collection media on sperm fertility after cryopreservation. Our results indicate that murine spermatozoa collected in media with different osmolalities (290 and 415 mmol/kg Dulbecco's phosphate buffered saline (DPBS)) appeared to have different osmotic tolerances for the maintenance of sperm motility and other motion parameters in both mouse strains. The hypo- and hyperosmotic treatments decreased motility and affected other motion parameters of spermatozoa collected in 290 mmol/kg DPBS. The extent of the change of motion parameters after treatments corresponded with the levels of osmotic stress. However, for spermatozoa collected in 415 mmol/kg DPBS, exposure to 290 mmol/kg DPBS tended to increase sperm motility and the quality of their motion parameters. The osmolality of sperm collection medium can affect murine sperm fertility. Spermatozoa collected in 415 mmol/kg medium showed higher fertility compared with spermatozoa collected in 290 mmol/kg as assessed by IVF. Results characterizing murine sperm osmotic tolerance collected in media with different osmolalities from different strains and the effect of collection media osmolality on sperm fertility after cryopreservation will be useful in designing cryopreservation protocols.

Interactions of GRF(1-29)NH2 with plasma proteins and their effects on the release of the peptide from a PLAGA matrix.

PubMed

Mariette, B; Coudane, J; Vert, M

2005-09-02

The administration of the GRF(1-29)NH2 Growth Hormone Releasing Hormone analog is known as relevant of the concept of drug delivery system using a bioresorbable matrix. However, the release of this peptide from poly(dl-lactic acid-co-glycolic acid) matrices is affected by its insolubility at neutral in salted media and in plasma as well. In order to investigate the origin and the nature of the insolubility in these media in more details, the precipitates collected when the peptide was set in contact with saline, isotonic pH=7.4 phosphate buffer and plasma were analyzed by various techniques, namely weighting, gel chromatography, 1D- and 2D-immunoelectrophoresis, and dialysis to discern the soluble from the insoluble or aggregated fractions. It is shown that precipitation in protein-free salted media is due to a salting out phenomenon complemented by the neutralization of the solubilizing electrostatic charges in the isotonic buffer. In contrast, the precipitation in plasma is due to inter polyelectrolyte-type complexation that involved polyanionic proteins having a rather low isoelectric point like albumin, transferin, haptoglobulin and IgG immunoglobulins. When a rather large quantity of GRF(1-29)NH2 was entrapped in bioresorbable pellets working at a percolating regime after subcutaneous implantation in rats, the peptide was slowly released despite the complexation with plasma proteins. However only a very small part of the peptide was found in blood, this small part being still large enough to cause a detectable increase of the circulating growth hormone concentration. Attempts made to increase the solubility of the peptide in plasma were successful when the peptide was combined with arginine, an amino acid known to promote the poor hormonal activity of injected GRF(1-29)NH2 solutions under clinical conditions.

Evaluation of a newly developed triple buffered peptone broth for detection of Salmonella in broiler feed

USDA-ARS?s Scientific Manuscript database

Lactose broth (LB) and buffered peptone (BP) are used as pre-enrichment media to recover Salmonella from feed. Bacterial utilization of feed carbohydrates results in the production of acidic byproducts causing a drop in the media pH which can injure or kill Salmonella and yield false negative resul...

The Preparation of Capsaicin-Chitosan Microspheres (CCMS) Enteric Coated Tablets

PubMed Central

Chen, Jian; Huang, Gui-Dong; Tan, Si-Rong; Guo, Jiao; Su, Zheng-Quan

2013-01-01

This study aimed to research the preparation and content determination of capsaicin-chitosan microspheres (CCMS) enteric coated tablets. The core tablets were prepared with the method of wet granulation. Nine formulae were designed to determine the optimal formula of the core tablet. Eudragit L100 was used to prepare the CCMS enteric-coated tablets. The effect of enteric coated formulation variables such as content of talc (10%, 25% and 40%), plasticisers (TEC and DBS), dosage of plasticiser (10%, 20% and 30%) and coating weight (2%, 3% and 5%) were evaluated for drug release characteristics. The in vitro release was studied using 0.1 N HCl and pH 6.8 phosphate buffer. Enteric coated tablets without ruptures or swelling behaviour over 2 h in 0.1 N HCl indicated that these tablets showed acid resistance. The accumulated release rate in phosphate buffer (pH 6.8) revealed that the prepared tablets were able to sustain drug release into the intestine and a first-order release was obtained for capsaicin. This research is the first report of the preparation and content determination of CCMS enteric coated tablets. The sustained release behavior of enteric coated formulations in pH 6.8 phosphate buffer demonstrated that it would be a potential drug delivery platform for sustained delivery of gastric irritant drugs. PMID:24351818

Albumin adsorption onto surfaces of urine collection and analysis containers☆

PubMed Central

Robinson, Mary K.; Caudill, Samuel P.; Koch, David D.; Ritchie, James; Hortin, Glen; Eckfeldt, John H.; Sandberg, Sverre; Williams, Desmond; Myers, Gary; Miller, W. Greg

2017-01-01

Background Adsorption of albumin onto urine collection and analysis containers may cause falsely low concentrations. Methods We added 125I-labeled human serum albumin to urine and to phosphate buffered solutions, incubated them with 22 plastic container materials and measured adsorption by liquid scintillation counting. Results Adsorption of urine albumin (UA) at 5–6 mg/l was <0.9%; and at 90 mg/l was <0.4%. Adsorption was generally less at pH 8 than pH 5 but only 3 cases had p <0.05. Adsorption from 11 unaltered urine samples with albumin 5–333 mg/l was <0.8%. Albumin adsorption for the material with greatest binding was extrapolated to the surface areas of 100 ml and 2 l collection containers, and to instrument sample cups and showed <1% change in concentration at 5 mg/l and <0.5% change at 20 mg/l or higher concentrations. Adsorption of albumin from phosphate buffered solutions (2–28%) was larger than that from urine. Conclusions Albumin adsorption differed among urine samples and plastic materials, but the total influence of adsorption was <1% for all materials and urine samples tested. Adsorption of albumin from phosphate buffered solutions was larger than that from urine and could be a limitation for preparations used as calibrators. PMID:24513540

Albumin adsorption onto surfaces of urine collection and analysis containers.

PubMed

Robinson, Mary K; Caudill, Samuel P; Koch, David D; Ritchie, James; Hortin, Glen; Eckfeldt, John H; Sandberg, Sverre; Williams, Desmond; Myers, Gary; Miller, W Greg

2014-04-20

Adsorption of albumin onto urine collection and analysis containers may cause falsely low concentrations. We added (125)I-labeled human serum albumin to urine and to phosphate buffered solutions, incubated them with 22 plastic container materials and measured adsorption by liquid scintillation counting. Adsorption of urine albumin (UA) at 5-6 mg/l was <0.9%; and at 90 mg/l was <0.4%. Adsorption was generally less at pH8 than pH5 but only 3 cases had p<0.05. Adsorption from 11 unaltered urine samples with albumin 5-333 mg/l was <0.8%. Albumin adsorption for the material with greatest binding was extrapolated to the surface areas of 100 ml and 2l collection containers, and to instrument sample cups and showed <1% change in concentration at 5 mg/l and <0.5% change at 20 mg/l or higher concentrations. Adsorption of albumin from phosphate buffered solutions (2-28%) was larger than that from urine. Albumin adsorption differed among urine samples and plastic materials, but the total influence of adsorption was <1% for all materials and urine samples tested. Adsorption of albumin from phosphate buffered solutions was larger than that from urine and could be a limitation for preparations used as calibrators. Copyright © 2014 Elsevier B.V. All rights reserved.

Simple and sensitive determination of five quinolones in food by liquid chromatography with fluorescence detection.

PubMed

Ramos, Macarena; Aranda, Angela; Garcia, Elena; Reuvers, Thea; Hooghuis, Henny

2003-06-15

A simple and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the determination of five different quinolones: enrofloxacin, ciprofloxacin, sarafloxacin, oxolinic acid and flumequine in pork and salmon muscle. The method includes one extraction and clean-up step for the five quinolones together which are detected in two separated HPLC runs by means of their fluorescence. The proposed analytical method involves homogenizing of the tissue sample with 0.05 M phosphate buffer, pH 7.4 and clean-up by Discovery DS-18 cartridges. For chromatographic separation a Symmetry C(18) column is used in two different runs: (1) ciprofloxacin, enrofloxacin and sarafloxacin with acetonitrile-0.02 M phosphate buffer pH 3.0 (18:82) as mobile phase and the detector at excitation wavelength: 280 nm and emission wavelength 450 nm; and (2) oxolinic acid and flumequine with acetonitrile-0.02 M phosphate buffer pH 3.0 (34:66) as mobile phase and excitation wavelength: 312 nm and emission wavelength: 366 nm. Detection limit was as low as 5 ng g(-1), except for sarafloxacin which had a limit of 10 ng g(-1). Standard curves using blank muscle tissues spiked at different levels showed a good linear correlation coefficient, r(2) higher than 0.999 for all quinolones.

Precipitation of Phosphate Minerals by Microorganisms Isolated from a Fixed-Biofilm Reactor Used for the Treatment of Domestic Wastewater

PubMed Central

Rivadeneyra, Almudena; Gonzalez-Martinez, Alejandro; Gonzalez-Lopez, Jesus; Martin-Ramos, Daniel; Martinez-Toledo, Maria Victoria; Rivadeneyra, Maria Angustias

2014-01-01

The ability of bacteria isolated from a fixed-film bioreactor to precipitate phosphate crystals for the treatment of domestic wastewater in both artificial and natural media was studied. When this was demonstrated in artificial solid media for crystal formation, precipitation took place rapidly, and crystal formation began 3 days after inoculation. The percentage of phosphate-forming bacteria was slightly higher than 75%. Twelve major colonies with phosphate precipitation capacity were the dominant heterotrophic platable bacteria growing aerobically in artificial media. According to their taxonomic affiliations (based on partial sequencing of the 16S rRNA), the 12 strains belonged to the following genera of Gram-negative bacteria: Rhodobacter, Pseudoxanthobacter, Escherichia, Alcaligenes, Roseobacter, Ochrobactrum, Agromyce, Sphingomonas and Paracoccus. The phylogenetic tree shows that most of the identified populations were evolutionarily related to the Alphaproteobacteria (91.66% of sequences). The minerals formed were studied by X-ray diffraction, scanning electron microscopy (SEM), and energy dispersive X-ray microanalysis (EDX). All of these strains formed phosphate crystals and precipitated struvite (MgNH4PO4·6H2O), bobierrite [Mg3(PO4)2·8H2O] and baricite [(MgFe)3(PO4)2·8H2O]. The results obtained in this study show that struvite and spherulite crystals did not show any cell marks. Moreover, phosphate precipitation was observed in the bacterial mass but also near the colonies. Our results suggest that the microbial population contributed to phosphate precipitation by changing the media as a consequence of their metabolic activity. Moreover, the results of this research suggest that bacteria play an active role in the mineral precipitation of soluble phosphate from urban wastewater in submerged fixed-film bioreactors. PMID:24699031

The preparation and the sustained release of titanium dioxide hollow particles encapsulating L-ascorbic acid

NASA Astrophysics Data System (ADS)

Tominaga, Yoko; Kadota, Kazunori; Shimosaka, Atsuko; Yoshida, Mikio; Oshima, Kotaro; Shirakawa, Yoshiyuki

2018-05-01

The preparation of the titanium dioxide hollow particles encapsulating L-ascorbic acid via sol-gel process using inkjet nozzle has been performed, and the sustained release and the effect protecting against degradation of L-ascorbic acid in the particles were investigated. The morphology of titanium dioxide particles was evaluated by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The sustained release and the effect protecting against degradation of L-ascorbic acid were estimated by dialysis bag method in phosphate buffer saline (PBS) (pH = 7.4) as release media. The prepared titanium dioxide particles exhibited spherical porous structures. The particle size distribution of the titanium dioxide particles was uniform. The hollow titanium dioxide particles encapsulating L-ascorbic acid showed the sustained release. It was also found that the degradation of L-ascorbic acid could be inhibited by encapsulating L-ascorbic acid in the titanium dioxide hollow particles.

Improved quantitative recovery of Listeria monocytogenes from stainless steel surfaces using a one-ply composite tissue.

PubMed

Vorst, Keith L; Todd, Ewen C D; Rysert, Elliot T

2004-10-01

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

Gold and Iron Oxide Nanoparticle-Based Ethylcellulose Nanocapsules for Cisplatin Drug Delivery

PubMed Central

Sathish Kumar, Kannaiyan; Jaikumar, Vasudevan

2011-01-01

The present study is aimed at the overall improvement in the efficacy, reduced toxicity and enhancement of therapeutic index of cisplatin. Nanocapsules of cisplatin containing ethylcellulose have been prepared using solvent evaporation technique under ambient conditions. The prepared nanocapsules were used for controlled drug release of anticancer agents with gold and iron oxide nanoparticles. The drug-entrapped nanocapsules were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Fourier transform infrared (FTIR) studies indicated the absence of chemical interactions between the drug, polymer and metal nanoparticles. The drug loaded nanoparticles are spherical in shape and had average diameter in the range of 100-300 nm. Drug release study showed that the acidic media provided a faster release than the phosphate buffer media. These findings were also compared statistically through calculating mean, standard deviation and coefficient of variation for various polymer nanocapsules. However, the drug release for gold nanoparticles/anticancer drug (Au-cis) incorporated ethylcellulose nanocapsules was controlled and slow compared to iron oxide nanoparticles-cisplatin incorporated ethylcellulose nanocapsules. Hence, gold nanoparticles act as good trapping agents which slow down the rate of drug release from nanocapsules. PMID:24250373

Erosion of water-based cements evaluated by volumetric and gravimetric methods.

PubMed

Nomoto, Rie; Uchida, Keiko; Momoi, Yasuko; McCabe, John F

2003-05-01

To compare the erosion of glass ionomer, zinc phosphate and polycarboxylate cements using volumetric and gravimetric methods. For the volumetric method, the eroded depth of cement placed in a cylindrical cavity in PMMA was measured using a dial gauge after immersion in an eroding solution. For the gravimetric method, the weight of the residue of a solution in which a cylindrical specimen had been immersed was measured. 0.02 M lactic acid solution (0.02 M acid) and 0.1 M lactic acid/sodium lactate buffer solution (0.1 M buffer) were used as eroding solutions. The pH of both solutions was 2.74 and the test period was 24 h. Ranking of eroded depth and weight of residue was polycarboxylate>zinc phosphate>glass ionomers. Differences in erosion were more clearly defined by differences in eroded depth than differences in weight of residue. In 0.02 M acid, the erosion of glass ionomer using the volumetric method was effected by the hygroscopic expansion. In 0.1 M buffer, the erosion for polycarboxylate and zinc phosphate using the volumetric method was much greater than that using the gravimetric method. This is explained by cryo-SEM images which show many holes in the surface of specimens after erosion. It appears that zinc oxide is dissolved leaving a spongy matrix which easily collapses under the force applied to the dial gauge during measurement. The volumetric method that employs eroded depth of cement using a 0.1 M buffer solution is able to quantify erosion and to make material comparisons.

Influence of diluent and sample processing methods on the recovery of the biocontrol agent Pantoea agglomerans CPA-2 from different fruit surfaces.

PubMed

Torres, R; Viñas, I; Usall, J; Remón, D; Teixidó, N

2012-08-01

Determining the populations of biocontrol agents applied as a postharvest treatment on fruit surfaces is fundamental to the assessment of the microorganisms' ability to colonise and persist on fruit. To obtain maximum recovery, we must develop a methodology that involves both diluent and processing methods and that does not affect the viability of the microorganisms. The effect of diluent composition was evaluated using three diluents: phosphate buffer, peptone saline and buffered peptone saline. An additional study was performed to compare three processing methods (shaking plus sonication, stomaching and shaking plus centrifugation) on the recovery efficiency of Pantoea agglomerans strain CPA-2 from apples, oranges, nectarines and peaches treated with this biocontrol agent. Overall, slight differences occurred among diluents, although the phosphate buffer maintained the most ideal pH for CPA-2 growth (between 5.2 and 6.2). Stomaching, using the phosphate buffer as diluent, was the best procedure for recovering and enumerating the biocontrol agent; this fact suggested that no lethal effects from naturally occurring antimicrobial compounds present on the fruit skins and/or produced when the tissues were disrupted affected the recovery of the CPA-2 cells, regardless of fruit type. The growth pattern of CPA-2 on fruits maintained at 20°C and under cold conditions was similar to that obtained in previous studies, which confirms the excellent adaptation of this strain to conditions commonly used for fruit storage. Copyright © 2012 Elsevier B.V. All rights reserved.

Attenuation of Phosphate Starvation Responses by Phosphite in Arabidopsis1

PubMed Central

Ticconi, Carla A.; Delatorre, Carla A.; Abel, Steffen

2001-01-01

When inorganic phosphate is limiting, Arabidopsis has the facultative ability to metabolize exogenous nucleic acid substrates, which we utilized previously to identify insensitive phosphate starvation response mutants in a conditional genetic screen. In this study, we examined the effect of the phosphate analog, phosphite (Phi), on molecular and morphological responses to phosphate starvation. Phi significantly inhibited plant growth on phosphate-sufficient (2 mm) and nucleic acid-containing (2 mm phosphorus) media at concentrations higher than 2.5 mm. However, with respect to suppressing typical responses to phosphate limitation, Phi effects were very similar to those of phosphate. Phosphate starvation responses, which we examined and found to be almost identically affected by both anions, included changes in: (a) the root-to-shoot ratio; (b) root hair formation; (c) anthocyanin accumulation; (d) the activities of phosphate starvation-inducible nucleolytic enzymes, including ribonuclease, phosphodiesterase, and acid phosphatase; and (e) steady-state mRNA levels of phosphate starvation-inducible genes. It is important that induction of primary auxin response genes by indole-3-acetic acid in the presence of growth-inhibitory Phi concentrations suggests that Phi selectively inhibits phosphate starvation responses. Thus, the use of Phi may allow further dissection of phosphate signaling by genetic selection for constitutive phosphate starvation response mutants on media containing organophosphates as the only source of phosphorus. PMID:11706178

An efficient buffer-mediated control between free radical substitution and proton-coupled electron transfer: dehalogenation of iodoethane by the α-hydroxyethyl radical in aqueous solution.

PubMed

Ljubić, Ivan; Matasović, Brunislav; Bonifačić, Marija

2013-11-07

A remarkable buffer-mediated control between free-radical substitution (FRS) and proton-coupled electron transfer (PCET) is demonstrated for the reaction between iodoethane and the α-hydroxyethyl radical in neutral aqueous solution in the presence of bicarbonate or phosphate buffer. The reaction is initiated by the γ-radiolysis of the water solvent, and the products, either the iodine atom (FRS) or anion (PCET), are analysed using ion chromatographic and spectrophotometric techniques. A detailed insight into the mechanism is gained by employing density functional theory (M06-2X), Møller-Plesset perturbation treatment to the second order (MP2), and multireference methods (CASSCF/CASPT2). Addition of a basic buffer anion is indispensable for the reaction to occur and the competition between the two channels depends subtly on its proton accepting affinity, with FRS being the dominant channel in the phosphate and PCET in the bicarbonate containing solutions. Unlike the former, the latter channel sustains a chain-like process which significantly enhances the dehalogenation. The present systems furnish an example of the novel PCET/FRS dichotomy, as well as insights into possibilities of its efficient control.

In vitro behaviour of three biocompatible glasses in composite implants.

PubMed

Varila, Leena; Lehtonen, Timo; Tuominen, Jukka; Hupa, Mikko; Hupa, Leena

2012-10-01

Poly(L,DL-lactide) composites containing filler particles of bioactive glasses 45S5 and S53P4 were compared with a composite containing a slowly dissolving glass S68. The in vitro reactivity of the composites was studied in simulated body fluid, Tris-buffered solution, and phosphate buffered saline. The high processing temperature induced thermal degradation giving cavities in the composites containing 45S5 and S53P4, while good adhesion of S68 to the polymer was observed. The cavities partly affected the in vitro reactivity of the composites. The degradation of the composites containing the bioactive glasses was faster in phosphate buffered saline than in the two other solutions. Hydroxyapatite precipitation suggesting bone tissue bonding capability was observed on these two composites in all three solutions. The slower dissolution of S68 glass particles and the limited hydroxyapatite precipitation suggested that this glass has potential as a reinforcing composition with the capability to guide bone tissue growth in biodegradable polymer composites.

Preparation, characterization and in vitro release study of carvacrol-loaded chitosan nanoparticles.

PubMed

Keawchaoon, Lalita; Yoksan, Rangrong

2011-05-01

The fabrication of carvacrol-loaded chitosan nanoparticles was achieved by a two-step method, i.e., oil-in-water emulsion and ionic gelation of chitosan with pentasodium tripolyphosphate. The obtained particles possessed encapsulation efficiency (EE) and loading capacity (LC) in the ranges of 14-31% and 3-21%, respectively, when the initial carvacrol content was 0.25-1.25 g/g of chitosan. The individual particles exhibited a spherical shape with an average diameter of 40-80 nm, and a positively charged surface with a zeta potential value of 25-29 mV. The increment of initial carvacrol content caused a reduction of surface charge. Carvacrol-loaded chitosan nanoparticles showed antimicrobial activity against Staphylococcus aureus, Bacillus cereus and Escherichia coli with an MIC of 0.257 mg/mL. The release of carvacrol from chitosan nanoparticles reached plateau level on day 30, with release amounts of 53% in acetate buffer solution with pH of 3, and 23% and 33% in phosphate buffer solutions with pH of 7 and 11, respectively. The release mechanism followed a Fickian behavior. The release rate was superior in an acidic medium to either alkaline or neutral media, respectively. Copyright © 2011 Elsevier B.V. All rights reserved.

Hybrid polyurea elastomers with enzymatic degradation and tunable mechanical properties

PubMed Central

Sears, Nicholas A; Pena-Galea, Geraldine; Cereceres, Stacy N; Cosgriff-Hernandez, Elizabeth

2016-01-01

Herein, we report on the synthesis and characterization of enzymatically labile polyureas for use as a tissue-engineered ligament scaffold. Polyureas were selected due to their excellent tensile properties, fatigue resistance, and highly tunable nature. Incorporation of a collagenase-sensitive peptide into the backbone of the polyurea provided a means to confer cell-responsive degradation to the synthetic polymer. Chemical, morphological, and mechanical testing were used to confirm incorporation of the peptide and characterize polyurea films. Notably, the incorporation of the peptide resulted in an increase in modulus, elongation, and tensile strength. This was attributed to an increase in phase mixing and an increase in hydrogen bonding between the hard and soft segments. Candidate polyureas with varying levels of collagen-mimetic peptide (0%, 10%, 20%) were then subjected to degradation in collagenase media or buffer at 37°C over 4 weeks. Statistically significant decreases in strength and elongation were observed in polyureas with 20% peptide content after collagenase treatment, whereas specimens in phosphate-buffered saline showed no statistically significant difference. These observations confirmed that enzyme-specific degradation was conferred to the polyurea. Overall, these polyureas hold great promise as a material for ligament reconstruction due to the promising mechanical properties and potential for cell-mediated degradation. PMID:27994846

Spermatozoa isolated from cat testes retain their structural integrity as well as a developmental potential after refrigeration for up to 7 days.

PubMed

Buarpung, Sirirak; Tharasanit, Theerawat; Thongkittidilok, Chommanart; Comizzoli, Pierre; Techakumphu, Mongkol

2015-10-01

The objective of this study was to compare the efficiency of preservation media for isolated feline testicular spermatozoa as well as the concentrations of bovine serum albumin (BSA) on: (1) the membrane (sperm membrane integrity (SMI)) and DNA integrity of spermatozoa; and (2) the developmental potential of spermatozoa after intracytoplasmic sperm injection (ICSI). Isolated cat spermatozoa were stored in HEPES-M199 medium (HM) or Dulbecco's phosphate-buffered saline (DPBS) at 4°C for up to 7 days. Results indicated that HM maintained a better SMI than DPBS throughout the storage periods (P > 0.05). When spermatozoa were stored in HM supplemented with BSA at different concentrations (4, 8 or 16 mg/ml), SMI obtained from HM containing 8 and 16 mg/ml BSA was higher than with 4 mg/ml BSA (P 0.05). In summary, cat spermatozoa immediately isolated from testicular tissue can be stored as a suspension in basic buffered medium at 4°C for up to 7 days. BSA supplementation into the medium improves membrane integrity of the spermatozoa during cold storage. Testicular spermatozoa stored in HM containing 16 mg/ml BSA retained full in vitro developmental potential after ICSI, similar to that of fresh controls even though DNA integrity had slightly declined.

Performance of transport and selective media for swine Bordetella bronchiseptica recovery and it comparison to polymerase chain reaction detection

PubMed Central

Coutinho, Tania Alen; Bernardi, Mari Lourdes; de Itapema Cardoso, Marisa Ribeiro; Borowski, Sandra Maria; Moreno, Andrea Micke; de Barcellos, David Emilio Santos Neves

2009-01-01

Three comparative assays were performed seeking to improve the sensitivity of the diagnosis of Bordetella bronchiseptica infection analyzing swine nasal swabs. An initial assay compared the recovery of B. bronchiseptica from swabs simultaneously inoculated with B. bronchiseptica and some interfering bacteria, immersed into three transport formulations (Amies with charcoal, trypticase soy broth and phosphate buffer according to Soerensen supplemented with 5% of bovine fetal serum) and submitted to different temperatures (10°C and 27°C) and periods of incubation (24, 72 and 120 hours). A subsequent assay compared three selective media (MacConkey agar, modified selective medium G20G and a ceftiofur medium) for their recovery capabilities from clinical specimens. One last assay compared the polymerase chain reaction to the three selective media. In the first assay, the recovery of B. bronchiseptica from transport systems was better at 27°C and the three formulations had good performances at this temperature, but the collection of qualitative and quantitative analysis indicated the advantage of Amies medium for nasal swabs transportation. The second assay indicated that MacConkey agar and modified G20G had similar results and were superior to the ceftiofur medium. In the final assay, polymerase chain reaction presented superior capability of B. bronchiseptica detection to culture procedures. PMID:24031390

Physicochemical and biological characterization of single-walled and double-walled carbon nanotubes in biological media.

PubMed

Liu, Wen-Te; Bien, Mauo-Ying; Chuang, Kai-Jen; Chang, Ta-Yuan; Jones, Tim; BéruBé, Kelly; Lalev, Georgi; Tsai, Dai-Hua; Chuang, Hsiao-Chi; Cheng, Tsun-Jen

2014-09-15

To study the toxicity of nanoparticles under relevant conditions, it is important to reproducibly disperse nanoparticles in biological media in in vitro and in vivo studies. Here, single-walled nanotubes (SWNTs) and double-walled nanotubes (DWNTs) were physicochemically and biologically characterized when dispersed in phosphate-buffered saline (PBS) and bovine serum albumin (BSA). BSA-SWNT/DWNT interaction resulted in a reduction of aggregation and an increase in particle stabilization. Based on the protein sequence coverage and protein binding results, DWNTs exhibited higher protein binding than SWNTs. SWNT and DWNT suspensions in the presence of BSA increased interleukin-6 (IL-6) levels and reduced tumor necrosis factor-alpha (TNF-α) levels in A549 cells as compared to corresponding samples in the absence of BSA. We next determined the effects of SWNTs and DWNTs on pulmonary protein modification using bronchoalveolar lavage fluid (BALF) as a surrogate collected form BALB/c mice. The BALF proteins bound to SWNTs (13 proteins) and DWNTs (11 proteins), suggesting that these proteins were associated with blood coagulation pathways. Lastly, we demonstrated the importance of physicochemical and biological alterations of SWNTs and DWNTs when dispersed in biological media, since protein binding may result in the misinterpretation of in vitro results and the activation of protein-regulated biological responses. Crown Copyright © 2014. Published by Elsevier B.V. All rights reserved.

Toposelective electrochemical desorption of thiol SAMs from neighboring polycrystalline gold surfaces.

PubMed

Tencer, Michal; Berini, Pierre

2008-11-04

We describe a method for the selective desorption of thiol self-assembled monolayers from gold surfaces having micrometer-scale separations on a substrate. In an electrolyte solution, the electrical resistance between the adjacent areas can be much lower than the resistance between a surface and the counter electrode. Also, both reductive and oxidative thiol desorption may occur. Therefore, the potentials of the surfaces must be independently controlled with a multichannel potentiostat and operating windows for a given thiol/electrolyte system must be established. In this study operating windows were established for 1-dodecanethiol-based SAMs in phosphate buffer, phosphate-buffered saline, and sodium hydroxide solution, and selective SAM removal was successfully performed in a four-electrode configuration.

Investigation of drug loading and in vitro release mechanisms of insulin-lauryl sulfate complex loaded PLGA nanoparticles.

PubMed

Shi, K; Cui, F; Yamamoto, H; Kawashima, Y

2008-12-01

Insulin, a water soluble peptide hormone, was hydrophobically ion-paired with sodium lauryl sulfate (SDS) at the stoichiometric molar ratio of 6:1. The obtained insulin-SDS complex precipitation was subsequently formulated in biodegradable poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles by a modified spontaneous emulsion solvent diffusion method. Compared with a conventional method for free insulin encapsulation, direct dissolution of SDS-paired insulin in the non-aqueous organic phase led to an increase in drug recovery from 42.5% to 89.6%. The more hydrophobic complex contributes to the improved affinity of insulin to the polymer matrix, resulting in a higher drug content in the nanoparticles. The drug loading was investigated by determining initial burst release at the first 30 min. The results showed that 64.8% of recovered drug were preferentially surface bound on complex loaded nanoparticles. The in vitro drug release was characterized by an initial burst and subsequent delayed release in dissolution media of deionized water and phosphate buffer saline (PBS). Compared with that in PBS, nanoparticles in deionized water medium presented very low initial burst release (15% vs. 65%) and incomplete cumulative release (25% vs. 90%) of the drug. In addition, dialysis experiments were performed to clarify the form of the released insulin in the dissolution media. The results suggested that the ion-pair complex was sensitive to ionic strength, insulin was released from the particular matrix as complex form and subsequently suffered dissociation from SDS in buffer saline. Moreover, the in vivo bioactivity of the SDS-paired insulin and nanoparticulate formulations were evaluated in mice by estimation of their blood sugar levels. The results showed that the bioactivity of insulin was unaltered after the ion-pairing process.

Anolyte recycling enhanced bioelectricity generation of the buffer-free single-chamber air-cathode microbial fuel cell.

PubMed

Ren, Yueping; Chen, Jinli; Shi, Yugang; Li, Xiufen; Yang, Na; Wang, Xinhua

2017-11-01

Anolyte acidification is an inevitable restriction for the bioelectricity generation of buffer-free microbial fuel cells (MFCs). In this work, acidification of the buffer-free KCl anolyte has been thoroughly eliminated through anolyte recycling. The accumulated HCO 3 - concentration in the recycled KCl anolyte was above 50mM, which played as natural buffer and elevated the anolyte pH to above 8. The maximum power density (P max ) increased from 322.9mWm -2 to 527.2mWm -2 , which is comparable with the phosphate buffered MFC. Besides Geobacter genus, the gradually increased anolyte pH and conductivity induced the growing of electrochemically active Geoalkalibacter genus, in the anode biofilm. Anolyte recycling is a feasible strategy to strengthen the self-buffering capacity of buffer-free MFCs, thoroughly eliminate the anolyte acidification and prominently enhance the electric power. Copyright © 2017 Elsevier Ltd. All rights reserved.

Site Targeted Press Coated Delivery of Methylprednisolone Using Eudragit RS 100 and Chitosan for Treatment of Colitis.

PubMed

Jagdale, Swati; Chandekar, Apoorva

2016-01-01

Inflammatory bowel disease (IBD) is one of the five most prevalent gastrointestinal disease burdens which commonly require lifetime care. Worldwide incidence rate of ulcerative colitis and Crohn's disease is about 16.8% and 13.4% respectively. Colitis is an inflammation of the colon. Colon targeted drug delivery will direct the drug to the colon. The drug will reach at the site of action and hence its side effects as well as dose can be reduced. Recent patent describes treatment of ulcerative colitis using anti CD3 antibodies, with nicotine and anti-depressant drugs, budesonide foam etc. Present study deals with optimization of site targeted methylprednisolone delivery for treatment of colitis. Chitosan and Eudragit RS 100 were used as coating polymers. Tablets were prepared by press coated technology. The core tablets contain drug, avicel as binder, croscarmellose sodium as super disintegrant and dicalcium phosphate as diluent. Drug excipient compatibility was carried out using FTIR, UV and DSC. Design of experiment was used to optimize the formulation. Tablets were evaluated for thickness, weight variation, hardness, swelling index, in-vitro drug release and release of drug in simulated media. Optimized batch (B2) contained chitosan 40% and eudragit RS 100 17.5%. B2 showed in-vitro drug release 85.65 ± 7.6% in 6.8 pH phosphate buffer and 96.7 ±9.1% in simulated media after 7.5 hours. In-vivo x-ray placebo study for formulation B2 had shown that the tablet reached to the ascending colon after 5 hours. This indicated a potential site targeted delivery of optimized batch B2.

14 million hours of operational experience on phosphate ester fluids as gas turbine main bearing lubricants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dufresne, P.E.

1998-09-01

Phosphate ester fluids have been used as a gas turbine main bearing lubricant for more than 35 years. Acid treatment systems utilizing fullers` earth and activated alumina have been used to remove acids produced during the PE fluid degradation process on an intermittent or continuous basis. Both acid adsorbing medias contribute metal soaps during the acid adsorbing process. Over time, the build-up of metal soaps significantly reduces the capability of the media to adsorb acids. The end result is escalating acid levels and fluid operating problems. The introduction of ion exchange as an acid adsorbing media has eliminated the catalyticmore » fluid degradation process, and offers phosphate ester users` extremely long fluid service life.« less

Comparative assay of glutathione S-transferase (GSTs) activity of excretory-secretory materials and somatic extract of Fasciola spp parasites.

PubMed

Alirahmi, Heshmatollah; Farahnak, Ali; Golmohamadi, Taghi; Esharghian, Mohammad Reza

2010-01-01

Fascioliasis is a worldwide parasitic disease in human and domestic animals. The causative agents of fascioliasis are Fasciola hepatica and Fasciola gigantica. In the recent years, fasciola resistance to drugs has been reported in the many of publications. Fasciola spp has detoxification system including GST enzyme which may be responsible for its resistance. Therefore , the aim of the study was to assay of GST enzyme activity in fasciola parasites. Fasciola gigantica and Fasciola hepatica helminths were collected from abattoir as a live and cultured in buffer media for 4 h at 37 °C. Excretory-Secretory products were collected and stored in -80◦C. F. gigantica and Fasciola hepatica were homogenized with homogenizing buffer in a glass homogenizer to prepare of somatic extract. Suspension was then centrifuged and supernatant was stored at -80°C. In order to assay the enzyme activity, excretory-secretory and somatic extracts in the form of cocktails (potassium phosphate buffer, reduced glutathione and 1-chloro-2,4-dinitrobenzene substrates) were prepared and their absorbance recorded for 5 minutes at 340 nm. The total and specific GST activity of F. gigantica somatic and ES products were obtained as 2916.00, 272.01 micromole/minute and 1.33, 1.70 micromole/minute/mg protein, respectively. Fasciola hepatica also showed 2705.00, 276.86 micromole/minute and 1.33, 1.52 micromole/minute/mg protein, respectively. These results are important for analysis of parasite survival / resistance to drugs which use for treatment of fascioliasis.

Buffer or Brake? The Role of Sexuality-Specific Parenting in Adolescents' Sexualized Media Consumption and Sexual Development.

PubMed

Overbeek, Geertjan; van de Bongardt, Daphne; Baams, Laura

2018-03-13

One main source of sexual socialization lies within family interactions. Especially sexuality-specific parenting may determine adolescents' sexual development-adolescents' sexual behavior and sexual risk behavior, sexualized media consumption and permissive sexual attitudes-to a significant extent, but different ideas exist about how this works. In this longitudinal study, we examined two hypotheses on how sexuality-specific parenting-parenting aimed specifically at children's sexual attitudes and behaviors-relates to adolescents' sexual development. A first buffer hypothesis states that parents' instructive media discussions with their children-called instructive mediation-buffers the effect of sexualized media consumption on adolescents' sexual attitudes and behavior and, vice versa, the effect of adolescents' sexual attitudes and behavior on sexualized media consumption. A second brake hypothesis states that parents, by communicating love-and-respect oriented sexual norms, slow down adolescents' development toward increased sexualized media use, permissive sexual attitudes, and sexual behavior and sexual risk behavior. Using four-wave longitudinal data from 514 Dutch adolescents aged 13-16 years (49.8% female), we found evidence to support a brake effect. More frequent parental communication of love-and-respect oriented sexual norms was associated with less permissive sexual attitudes and, for boys, with less advanced sexual behavior and a less rapid increase in sexual risk behavior. Parents' instructive mediation regarding adolescents' sexualized media consumption was associated with less permissive sexual attitudes at baseline, but only for girls. No systematic evidence emerged for a buffer effect of parents' instructive mediation. In conclusion, although our data seem to suggest that parent-child communication about sex is oftentimes "after the fact", we also find that more directive parental communication that conveys love-and-respect oriented sexual norms brake adolescents' move toward sexual maturity.

Interaction of two diclofenac acid salts with copolymers of ammoniomethacrylate: effect of additives and release profiles.

PubMed

Khalil, E; Sallam, A

1999-04-01

The copolymer of ammoniomethacrylate Eudragit RL (ERL) interacted with diclofenac acid salts (sodium and diethylamine salts) in aqueous solutions, forming a complex. Sorption experiments were done in aqueous solutions of either sodium lauryl sulfate (SLS), Tween 20, or Tween 80. The SLS competed strongly with the drug, even at low concentrations, and reduced significantly the amount of drug sorbed by ERL. Tweens at high concentrations exhibited two phase profiles: the sorption phase, which was short and during which drug concentration dropped sharply, and the release phase, during which the drug was released slowly over 24 hr and which was accompanied by dispersion of ERL particles into the colloidal dispersion. The interaction was dependent on temperature, ionic strength, and nature of the additives. The extent of interaction in water and phosphate buffer solutions was in the following order: water > pH 6 > pH 7-8. In-vitro dissolution studies of the dried complex were done over 24 hr. In water, the drug remained bound to the polymer. In aqueous surfactant solutions (SLS, Tween 20, and Tween 80) and phosphate buffer at pH 6.8, a linear relationship between drug concentration and the square root of time was obtained, indicating a matrix diffusion-controlled mechanism. However, 100% release was not reached, and resorption was observed in the phosphate buffer solution.

Layer by layer assembled films between hemoglobin and multiwall carbon nanotubes for pH-switchable biosensing.

PubMed

Pan, Zhongqin; Liu, Xiaojun; Xie, Jing; Bao, Ning; He, Hong; Li, Xiaodong; Zeng, Jiang; Gu, Haiying

2015-05-01

Although pH-switchable behaviors have been reported based on multilayer films modified electrodes, their pH-switchable biosensing is still difficult due to the existence of the electroactive mediator. In this study, we report the pH-dependable determination of hydrogen peroxide (H2O2) based on a four-bilayer film fabricated through layer by layer assembly between hemoglobin (Hb) and multiwall carbon nanotubes (MWCNTs). We observed that response of electroactive probe Fe(CN)6(3-) at the multilayer films was very sensitive and reversible to pH values of phosphate buffer solutions phosphate buffer solution with cyclic voltammetry. The reduction peak height of Fe(CN)6(3-) at the multilayer film could reach ∼221μA at pH 3.0 while 0μA at pH 9.0. The linear range for the detection of H2O2 at pH 3.0 was from 12.5μM to 10.4mM, which was much wider than that at pH 9.0. Our results demonstrated that the detection of H2O2 with the proposed modified electrode is dependent on pH values of phosphate buffer solution. Moreover, the component of multilayer films has impacts on the performance of biosensors with pH-switchable behaviors. Copyright © 2015 Elsevier B.V. All rights reserved.

A calorimetric investigation of the interaction of the lac repressor with inducer.

PubMed

Donnér, J; Caruthers, M H; Gill, S J

1982-12-25

A calorimetric study has been made of the interaction between the lac repressor and isopropyl-1-thio-beta-D-galactopyranoside (IPTG). The buffer-corrected enthalpy of reaction at 25 degrees C was found to be -15.6, -24.7, -4.6 kJ/mol of bound IPTG at pH 7.0, pH 8.1, and pH 9.0, respectively. This large range of enthalpy values is in contrast to a maximum difference in the free energy of the reaction of only 1.5 kJ/mol of bound IPTG between these pH values. The reaction was found by calorimetric measurements in different buffers to be accompanied by an uptake of 0.29 mol of protons/mol of bound IPTG at pH 8.1. The pH dependency of the reaction enthalpy suggests differences in the extent of protonation of the binding site and the involvement of H bonding with IPTG. The lack of strong hydrophobic contributions in the IPTG binding process is revealed by the absence of any determinable heat capacity change for the reaction at pH 7.0. The presence of phosphate buffer significantly alters the enthalpy of IPTG binding at higher pH values, but has little effect upon the binding constant. This implies that highly negative phosphate species change the nature of the IPTG binding site without any displacement of phosphate upon IPTG binding.

Mode changes associated with oil droplet movement in solutions of gemini cationic surfactants.

PubMed

Banno, Taisuke; Miura, Shingo; Kuroha, Rie; Toyota, Taro

2013-06-25

Micrometer-sized self-propelled oil droplets in nonequilibrium systems have attracted much attention, since they form stable emulsions composed of oil, water, and surfactant which represent a primitive type of inanimate chemical machinery. In this work, we examined means of controlling the movement of oil droplets by studying the dynamics of n-heptyloxybenzaldehyde droplets in phosphate buffers containing alkanediyl-α,ω-bis(N-dodecyl-N,N-dimethylammonium bromide) (nG12) with either tetramethylene (4G12), octaethylene (8G12), or dodecamethylene (12G12) chains in the linker moiety. Significant differences in droplet dynamics were observed to be induced by changes in the linker structure of these gemini cationic surfactants. In a phosphate buffer containing 30 mM 4G12, self-propelled motion of droplets concurrent with the formation of molecular aggregates on their surfaces was observed, whereas the fusion of oil droplets was evident in both 8G12 and 12G12 solutions. We also determined that the surface activities and the extent of molecular self-assembly of the surfactants in phosphate buffer were strongly influenced by the alkyl chain length in the linker moiety. We therefore conclude that the surface activities of the gemini cationic surfactant have important effects on the oil-water interfacial tension of oil droplets and the formation of molecular aggregates and that both of these factors induce the unique movement of the droplets.

(Poly)cation-induced protection of conventional and wireframe DNA origami nanostructures.

PubMed

Ahmadi, Yasaman; De Llano, Elisa; Barišić, Ivan

2018-04-26

DNA nanostructures hold immense potential to be used for biological and medical applications. However, they are extremely vulnerable towards salt depletion and nucleases, which are common under physiological conditions. In this contribution, we used chitosan and linear polyethyleneimine for coating and long-term stabilization of several three-dimensional DNA origami nanostructures. The impact of the degree of polymerization and the charge density of the polymer together with the N/P charge ratio (ratio of the amines in polycations to the phosphates in DNA) on the stability of encapsulated DNA origami nanostructures in the presence of nucleases and in low-salt media was examined. The polycation shells were compatible with enzyme- and aptamer-based functionalization of the DNA nanostructures. Additionally, we showed that despite being highly vulnerable to salt depletion and nucleolytic digestion, self-assembled DNA nanostructures are stable in cell culture media up to a week. This was contrary to unassembled DNA scaffolds that degraded in one hour, showing that placing DNA strands into a spatially designed configuration crucially affect the structural integrity. The stability of naked DNA nanostructures in cell culture was shown to be mediated by growth media. DNA origami nanostructures kept in growth media were significantly more resistant towards low-salt denaturation, DNase I and serum-mediated digestion than when in a conventional buffer. Moreover, we confirmed that DNA origami nanostructures remain not only structurally intact but also fully functional after exposure to cell media. Agarose gel electrophoresis and negative stain transmission electron microscopy analysis revealed the hybridization of DNA origami nanostructures to their targets in the presence of serum proteins and nucleases. The structural integrity and functionality of DNA nanostructures in physiological fluids validate their use particularly for short-time biological applications in which the shape and structural details of DNA nanodevices are functionally critical.

Evaluation of drug-metabolizing and functional competence of human hepatocytes incubated under hypothermia in different media for clinical infusion.

PubMed

Gómez-Lechón, María José; Lahoz, Agustín; Jiménez, Nuria; Bonora, Ana; Castell, José V; Donato, María Teresa

2008-01-01

Hepatocyte transplantation has been proposed as a method to support patients with liver insufficiency. Key factors for clinical cell transplantation to progress is to prevent hepatocyte damage, loss of viability and cell functionality, factors that depend on the nature of the tissue used for isolation to a large extent. The main sources of tissue for hepatocyte isolation are marginal livers that are unsuitable for transplantation, and segments from reduced cadaveric grafts. Hepatocellular transplantation requires infusing human hepatocytes in suspension over a period of minutes to hours. The beneficial effect of hypothermic preservation of hepatocytes in infusion medium has been reported, but how critical issues towards the success of cell transplantation, such as the composition of infusion medium and duration of hepatocyte storage will affect hepatocyte quality for clinical cell infusion has not been systematically investigated. Infusion media composition is phosphate-buffered saline containing anticoagulants and human serum albumin. The supplementation of infusion media with glucose or N-acetyl-cystein, or with both components at the same time, has been investigated. After isolation, hepatocytes were suspended in each infusion medium and a sample at the 0 time point was harvested for cell viability and functional assessment. Thereafter, cells were incubated in different infusion media agitated on a rocker platform to simulate the clinical infusion technique. The time course of hepatocyte viability, funtionality (drug-metabolizing enzymes, ureogenic capability, ATP, glycogen, and GSH levels), apoptosis (caspase-3 activation), and attachment and monolayer formation were analyzed. The optimal preservation of cell viability, attaching capacity, and functionality, particularly GSH and glycogen levels, as well as drug-metabolizing cytochrome P450 enzymes, was found in infusion media supplemented with 2 mM N-acetyl-cystein and 15 mM glucose.

Oligoglyceric acid synthesis by autocondensation of glyceroyl thioester

NASA Technical Reports Server (NTRS)

Weber, A. L.

1986-01-01

The autocondensation of the glyceroyl thioester, S-glyceroyl-ethane-thiol, yielded olioglyceric acid. The rates of autocondensation and hydrolysis of the thioester increased from pH 6.5 to pH 7.5 in 2,6-lutidine and imidazole buffers. Autocondensation and hydrolysis were much more rapid in imidazole buffers as compared to 2,6-lutidine and phosphate buffers. The efficiency of ester bond synthesis was about 20% for 40 mM S-glyceroyl-ethane-thiol in 2,6-lutidine and imidazole buffers near neutral pH. The size and yield of the olioglyceric acid products increased when the concentration of the thioester was increased. The relationship of these results to prebiotic polymer synthesis is discussed.

The importance of extracellular speciation and corrosion of copper nanoparticles on lung cell membrane integrity.

PubMed

Hedberg, Jonas; Karlsson, Hanna L; Hedberg, Yolanda; Blomberg, Eva; Odnevall Wallinder, Inger

2016-05-01

Copper nanoparticles (Cu NPs) are increasingly used in various biologically relevant applications and products, e.g., due to their antimicrobial and catalytic properties. This inevitably demands for an improved understanding on their interactions and potential toxic effects on humans. The aim of this study was to investigate the corrosion of copper nanoparticles in various biological media and to elucidate the speciation of released copper in solution. Furthermore, reactive oxygen species (ROS) generation and lung cell (A549 type II) membrane damage induced by Cu NPs in the various media were studied. The used biological media of different complexity are of relevance for nanotoxicological studies: Dulbecco's modified eagle medium (DMEM), DMEM(+) (includes fetal bovine serum), phosphate buffered saline (PBS), and PBS+histidine. The results show that both copper release and corrosion are enhanced in DMEM(+), DMEM, and PBS+histidine compared with PBS alone. Speciation results show that essentially no free copper ions are present in the released fraction of Cu NPs in neither DMEM(+), DMEM nor histidine, while labile Cu complexes form in PBS. The Cu NPs were substantially more membrane reactive in PBS compared to the other media and the NPs caused larger effects compared to the same mass of Cu ions. Similarly, the Cu NPs caused much more ROS generation compared to the released fraction only. Taken together, the results suggest that membrane damage and ROS formation are stronger induced by Cu NPs and by free or labile Cu ions/complexes compared with Cu bound to biomolecules. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

Characterizing fretting damage in different test media for cardiovascular device durability testing.

PubMed

Weaver, J D; Ramirez, L; Sivan, S; Di Prima, M

2018-06-01

In vitro durability tests of cardiovascular devices are often used to evaluate the potential for fretting damage during clinical use. Evaluation of fretting damage is important because severe fretting can concentrate stress and lead to the loss of structural integrity. Most international standards call for the use of phosphate buffered saline (PBS) for such tests although there has been little evidence to date that the use of PBS is appropriate in terms of predicting the amount of fretting damage that would occur in vivo. In order to determine an appropriate test media for in vitro durability tests where fretting damage is being evaluated, we utilized an in vitro test that is relevant to cardiovascular devices both in terms of dimensions and materials (nitinol, cobalt-chromium, and stainless steel) to characterize fretting damage in PBS, deionized water (DIW), and heparinized porcine blood. Overall, tests conducted in blood were found to have increased levels of fretting damage over tests in DIW or PBS, although the magnitude of this difference was smaller than the variability for each test media. Tests conducted in DIW and PBS led to mostly similar amounts of fretting damage with the exception of one material combination where DIW had greatly reduced damage compared to PBS and blood. Differences in fretting damage among materials were also observed with nitinol having less fretting damage than stainless steel or cobalt-chromium. In general, evaluating fretting damage in PBS or DIW may be appropriate although caution should be used when selecting test media and interpreting results given some of the differences observed across different materials. Published by Elsevier Ltd.

Evaluation of ocular and general safety following repeated dosing of dexamethasone phosphate delivered by transscleral iontophoresis in rabbits.

PubMed

Patane, Michael A; Schubert, William; Sanford, Thomas; Gee, Raymond; Burgos, Melissa; Isom, William P; Ruiz-Perez, Begona

2013-10-01

To evaluate the toxicokinetics and tolerability (local ocular and general toxicity) of the anti-inflammatory agent, dexamethasone phosphate (a prodrug of dexamethasone) delivered to the eye in rabbits by transscleral iontophoresis. Female rabbits (n=6/group) received dexamethasone phosphate (40 mg/mL ophthalmic solution, EGP-437) transsclerally to the right eye (OD) using the Eyegate(®) II ocular iontophoresis delivery system once biweekly for 24 consecutive weeks at current doses of 10, 14, and 20 mA-min and current levels up to, and including -4 mA for 3.5-5 min. The study included 2 control groups (n=6/group): (1) a noniontophoresis control [an ocular applicator-loaded citrate buffer (placebo) without current] and (2) an iontophoresis control (a citrate buffer plus cathode iontophoresis at 20 mA-min, -4 mA for 5 min). Recoverability was evaluated 4 weeks following the last dose in 2 animals per group. The left eye (OS) was untreated and served as an internal control for each animal. Ocular and general safety of dexamethasone phosphate and dexamethasone were assessed. Other evaluations included toxicokinetics, ophthalmic examinations, intraocular pressure (IOP) measurements, electroretinographs, clinical observations, body weight, hematology and serum chemistry, gross necropsy, organ weight, and microscopic histopathology. The biweekly transscleral iontophoresis with either the citrate buffer or dexamethasone phosphate at cathodic doses up to, and including 20 mA-min and currents up to, and including -4 mA for 24 weeks was well-tolerated. Transient signs of conjunctival hyperemia and chemosis, mild corneal opacity, and fluorescein staining of the cornea were noted and attributed to expected ocular reactions to the temporary placement of the ocular applicator and application of iontophoresis. There were no dexamethasone phosphate-, dexamethasone-, or iontophoresis-related effects on IOP, electroretinography, or histopathology. Reductions in body weight gain, anemia, decreased leukocyte and lymphocyte counts, compromised liver function, enlarged liver, and reduced spleen weight were consistent with systemic corticosteroid-mediated pharmacology, repeated use of anesthesia, stress, and sedentariness, and unlikely to be related to iontophoresis application. The results of this investigation suggest that repeated transscleral iontophoresis with dexamethasone phosphate may be safe for use as a treatment for inflammatory ocular disorders that require prolonged and/or repeated corticosteroid therapy.

Bioactive calcium phosphate-based glasses and ceramics and their biomedical applications: A review.

PubMed

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented.

Comparative studies in electrochemical degradation of sulfamethoxazole and diclofenac in water by using various electrodes and phosphate and sulfate supporting electrolytes.

PubMed

Sifuna, Fred W; Orata, Francis; Okello, Veronica; Jemutai-Kimosop, Selly

2016-09-18

In this study, the electro-oxidation capacities of Na2SO4 and potassium phosphate buffer supporting electrolytes were tested and compared for destruction of the sulfamethoxazole (SMX) and diclofenac (DCF) on platinum (Pt) electrode and graphite carbon electrode in aqueous medium. The suitability of pharmaceutical active compounds (PhACs) for electrochemical oxidation was tested by cyclic voltammetry (CV) technique performed in the potential range -1.5 to +1.5 V versus Ag/AgCl, which confirmed the electro-activity of the selected PhACs. The degradation and mineralization were monitored by ultraviolet (UV)-Vis spectrophotometry and HPLC. 0.1 M Na2SO4 supporting electrolyte was found to be more effective for mineralization of SMX and DCF, with efficiency of 15-30% more than the 0.1 M phosphate buffer supporting electrolyte on the platinum (Pt) and carbon electrodes. The Pt electrode showed better performance in the degradation of the two PhACs while under the same conditions than the carbon electrode for both 0.1 M Na2SO4 and 0.1 M potassium phosphate buffer supporting electrolytes. The SMX and DCF degradation kinetics best fitted the second-order reaction, with rate constants ranging between 0.000389 and 0.006 mol(2) L(-2) min(-1) and correlation coefficient (R(2)) above 0.987. The second-order degradation kinetics indicated that the rate-determining step in the degradation could be a chemical process, thus suggesting the active involvement of electrolyte radical species in the degradation of SMX and DCF. Results obtained from a real field sample showed a more than 98% removal of the PhACs from the wastewater by electrochemical degradation.

The effect of reaction conditions on formation of wet precipitated calcium phosphates

NASA Astrophysics Data System (ADS)

Huang, Chen; Cao, Peng

2015-03-01

The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for sample characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.

Structural characterization and dissolution profile of mycophenolic acid cocrystals.

PubMed

Zeng, Qing-Zhu; Ouyang, Jian; Zhang, Shuo; Zhang, Lei

2017-05-01

Three novel cocrystals of mycophenolic acid (MPA) with isonicotinamide (MPA-ISO), minoxidil (MPA-MIN) and 2,2'-dipyridylamine (MPA-DPA) as coformers have been prepared successfully by both slow evaporation and liquid-assisted grinding. The structures of these cocrystals show that all the three coformers form hydrogen bonds with the carboxylic acid group of MPA. The cocrystal MPA-ISO possesses remarkably improved solubility and dissolution rate, while two other cocrystals exhibit the opposite characteristics. The solids in the slurry with pH6.8 phosphate buffer and cocrystals remain as the incipient cocrystal after 24h. However, evidence of slight polymerization was shown in the slurry of pH6.8 phosphate buffer with MPA and MPA-ISO cocrystal. Copyright © 2017 Elsevier B.V. All rights reserved.

Stability of pseudorabies virus during freeze-drying and storage: effect of suspending media.

PubMed Central

Scott, E M; Woodside, W

1976-01-01

The effect of suspending media on the stability of pseudorabies virus upon freeze-drying and subsequent storage was studied. A variety of media was tested, including: sodium glutamate; sucrose; lactose; lactalbumin hydrolysate; peptone; a combination of sucrose, dextran, and glutamate; and various combinations of sucrose, glutamate, and potassium phosphates. Suspending media containing glutamate, either alone or in combination with sucrose and either dextran or phosphates, afforded the greatest degree of protection during the freeze-drying process and upon storage. Some possible functions of these additives in preventing injury to the virus during freezing and drying have been suggested. PMID:182713

Program on Resorbable Radio Devices

DTIC Science & Technology

2014-05-05

radio circuit - + PDMS Copper Mg PBS Buffer 1© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim wileyonlinelibrary.com Transient, Biocompatible...way, ZnO provides an alternative to silicon [ 16 ] or organic semi- conductors [ 17–20 ] for physically transient forms of electronics and sensors...immersion in several different types of solutions, such as phosphate buffer saline (PBS, pH 4.0, Sigma- Figure 1 . Materials and designs for

Effects of buffer composition and processing conditions on aggregation of bovine IgG during freeze-drying.

PubMed

Sarciaux, J M; Mansour, S; Hageman, M J; Nail, S L

1999-12-01

The objective of this study was to identify critical formulation and processing variables affecting aggregation of bovine IgG during freeze-drying when no lyoprotective solute is used. Parameters examined were phosphate buffer concentration and counterion (Na versus K phosphate), added salts, cooling rate, IgG concentration, residual moisture level, and presence of a surfactant. No soluble aggregates were detected in any formulation after either freezing/thawing or freeze-drying. No insoluble aggregates were detected in any formulation after freezing, but insoluble aggregate levels were always detectable after freeze-drying. The data are consistent with a mechanism of aggregate formation involving denaturation of IgG at the ice/freeze-concentrate interface which is reversible upon freeze-thawing, but becomes irreversible after freeze-drying and reconstitution. Rapid cooling (by quenching in liquid nitrogen) results in more and larger aggregates than slow cooling on the shelf of the freeze-dryer. This observation is consistent with surface area measurements and environmental electron microscopic data showing a higher surface area of freeze-dried solids after fast cooling. Annealing of rapidly cooled solutions results in significantly less aggregation in reconstituted freeze-dried solids than in nonannealed controls, with a corresponding decrease in specific surface area of the freeze-dried, annealed system. Increasing the concentration of IgG significantly improves the stability of IgG against freeze-drying-induced aggregation, which may be explained by a smaller percentage of the protein residing at the ice/freeze-concentrate interface as IgG concentration is increased. A sodium phosphate buffer system consistently results in more turbid reconstituted solids than a potassium phosphate buffer system at the same concentration, but this effect is not attributable to a pH shift during freezing. Added salts such as NaCl or KCl contribute markedly to insoluble aggregate formation. Both sodium and potassium chloride contribute more to turbidity of the reconstituted solid than either sodium or potassium phosphate buffers at similar ionic strength, with sodium chloride resulting in a substantially higher level of aggregates than potassium chloride. At a given cooling rate, the specific surface area of dried solids is approximately a factor of 2 higher for the formulation containing sodium chloride than the formulation containing potassium chloride. Turbidity is also influenced by the extent of secondary drying, which underscores the importance of minimizing secondary drying of this system. Including a surfactant such as polysorbate 80, either in the formulation or in the water used for reconstitution, decreased, but did not eliminate, insoluble aggregates. There was no correlation between pharmaceutically acceptability of the freeze-dried cake and insoluble aggregate levels in the reconstituted product.

Fundamental and Applied Studies of Polymer Membranes

NASA Astrophysics Data System (ADS)

Imbrogno, Joseph

Four major areas have been studied in this research: 1) synthesizing novel monomers, e.g. chiral monomers, to produce new types of functionalized membranes for the biotechnology and pharmaceutical industries, 2) hydrophobic brush membranes for desalinating brackish water, sea water, and separating organics, 3) fundamental studies of water interactions at surfaces using sum frequency generation (SFG), and 4) discovering new surface chemistries that will control the growth and differentiation of stem cells. We have developed a novel synthesis method in order to increase the breadth of our high throughput screening library. This library was generated using maleimide chemistry to react a common methacrylate linker with a variety of different functions groups (R groups) in order to form new monomers that were grafted from the surface of PES ultrafiltration membranes. From this work, we discovered that the chirality of a membrane can affect performance when separating chiral feed streams. This effect was observed when filtering bovine serum albumin (BSA) and ovalbumin in a high salt phosphate buffered saline (PBS, 150 mM salt). The Phe grafted membranes showed a large difference in performance when filtering BSA with selectivity of 1.13 and 1.00 for (S) and (R) Phe, respectively. However, when filtering ovalbumin, the (S) and (R) modified surfaces showed selectivity of 2.06 and 2.31, respectively. The higher selectivity enantiomer switched for the two different proteins. Permeability when filtering BSA was 3.06 LMH kPa-1 and 4.31 LMH kPa -1 for (S)- and (R)- Phe, respectively, and 2.65 LMH kPa -1 and 2.10 LMH kPa-1 when filtering ovalbumin for (S)- and (R)- Phe, respectively. Additionally, these effects were no longer present when using a low salt phosphate buffer (PB, 10 mM salt). Since, to our knowledge, membrane chirality is not considered in current industrial systems, this discovery could have a large impact on the pharmaceutical and biotechnology industries. We have developed hydrophobic brush membranes that were able to selectively separate valuable organics (isobutanol) from water, while rejecting other undesirable species, such as enzymes, using pervaporation (PV). These membranes (grafted from nanofiltration (NF) support membranes) had a selectivity ˜1.5x higher than the current industrial standard, polydimethylsiloxane (PDMS), with alpha = 10.1 +/- 0.9 for our brush membranes and alpha = 6.7 +/- 0.1 for PDMS membranes. Since the mechanism of pervaporation is based on the solution diffusion (SD) model, these membranes may be used to desalinate water or fractionate gases since they are also based on the SD mechanism. We have discovered that hydrophobic brush membranes are able to reject monovalent salt ions. This type of membrane is analogous to carbon nanotubes (CNTs), which are believed to have extremely high water fluxes through them due to near frictionless flow caused by a lack of hydrogen bonding. Using these brush membranes we were able to achieve 42% monovalent (NaCl) salt rejection of simulated seawater (32,000 ppm salt). These membranes are easier to scale-up than current composite membranes produced using interfacial polymerization. We have been using SFG to study interfacial water on membrane surfaces. We believe that water interactions with the membrane surface and with the feed species, e.g. proteins, play a critical role during the fouling process. Relevant buffers, such as phosphate buffered saline (PBS) and phosphate buffer, contain ions that are known to restructure water at interfaces. Sum frequency generation spectroscopy (SFG) was used to characterize interfacial water structure at poly(ether sulfone) (PES) thin films in the presence of 0.01 M phosphate buffer (low salt) and 0.01 M phosphate buffered saline (high salt). Three model surfaces were studied: unmodified PES, hydrophobic alkane (C18) modified PES, and poly(ethylene glycol) (PEG) modified PES. In the presence of the low salt phosphate buffer (10 mM salt), phosphate anions were excluded from the PEG-modified PES film. This led to a charge separation between the phosphate anions and sodium cations, creating a surface potential which strongly ordered water molecules into the bulk. When using high salt PBS (138 mM salt) the sodium chloride ions screened this charge and reduced water ordering. Interestingly, this effect was the greatest for the PEG modified surface, with minor or no effects observed for the C18 modified PES and unmodified PES, respectively. Using our high throughput screening platform, we were able to determine that (N-[3-(dimethylamino)propyl] methacrylamide), DMAPMA, supported strong attachment and long-term self-renewal of mouse embryonic stem (ES) cells while preventing differentiation (maintaining pluripotency). After developing this platform, it was used to screen for a surface that could instead induce differentiation of bovine and human retinal pigment epithelium (RPE) cells while promoting cell growth. Several PEG based surfaces were able to induce cobblestone morphology of the RPE cells, which is indicative of differentiation. (Abstract shortened by UMI.).

[High performance liquid chromatogram (HPLC) determination of adenosine phosphates in rat myocardium].

PubMed

Miao, Yu; Wang, Cheng-long; Yin, Hui-jun; Shi, Da-zhuo; Chen, Ke-ji

2005-04-18

To establish method for the quantitative determination of adenosine phosphates in rat myocardium by optimized high performance liquid chromatogram (HPLC). ODS HYPERSIL C(18) column and a mobile phase of 50 mmol/L tribasic potassium phosphate buffer solution (pH 6.5), with UV detector at 254 nm were used. The average recovery rates of myocardial adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were 99%-107%, 96%-104% and 95%-119%, respectively; relative standard deviations (RSDs) of within-day and between-days were less than 1.5% and 5.1%, respectively. The method is simple, rapid and accurate, and can be used to analyse the adenosine phosphates in myocardium.

Influence of some mononucleotides and their corresponding nucleosides on the metabolism of carbohydrates in the isolated rat diaphragm muscle

PubMed Central

Beloff-Chain, Anne; Betto, P.; Bleszynski, W.; Catanzaro, Raffaella; Chain, E. B.; Dmitrovskii, A. A.; Longinotti, L.; Pocchiari, F.

1965-01-01

1. The influence of ATP on glucose metabolism was studied in the isolated rat diaphragm; it was shown that ATP increases the oxidation of glucose and the aerobic conversion of glucose into lactate, whereas it decreases glycogen synthesis. There was no influence of ATP on the anaerobic formation of lactate from glucose. 2. A maximum effect of ATP on the oxidation of glucose (about 160% increase) was obtained in the presence of 10mm-ATP; in the presence of 2mm-ATP the effect was about 65%, and was approximately constant from 10 to 90min. incubation period. 3. In a phosphate-free tris-buffered medium the oxidation of glucose was considerably decreased, but the percentage stimulation by ATP was about the same as in a phosphate-buffered medium. 4. ATP was shown to increase the oxidation of fructose, glucose 6-phosphate, glucose 1-phosphate, fructose 1,6-diphosphate and, to a much smaller extent, pyruvate. 5. ADP stimulated the oxidation of glucose to the same extent as ATP at a concentration of 2mm and the effect with AMP was only slightly less; IMP and adenosine had only a small stimulatory effect at this concentration, whereas inosine had no effect. PMID:16749165

Final report of the key comparison APMP.QM-K91: APMP comparison on pH measurement of phthalate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Ketrin, Rosi; Nuryatini; Thanh, Ngo Huy; Truong Chinh, Nguyen; Vospelova, Alena; Bastkowski, Frank; Sander, Beatrice; Matzke, Jessica; Prokunin, Sergey; Frolov, Dmitry; Aprelev, Alexey; Dobrovolskiy, Vladimir; Uysal, Emrah; Liv, Lokman; Velina Lara-Manzano, Judith; Montero-Ruiz, Jazmin; Ortiz-Aparicio, JosÉ Luis; Ticona Canaza, Galia; Anuar Mohd Amin, Khirul; Abd Kadir, Haslina; Bakovets, Nickolay; Wong, Siu-Kay; Lam, Wai-Hing

2017-01-01

The APMP.QM-K91 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a phthalate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan at the APMP-TCQM meeting held September 22-23, 2014. After approval by TCQM, the comparison has been conducted by NMIJ. The comparison is a key comparison following CCQM-K91. The comparison material was a phthalate buffer of pH around 4.0 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the third APMP key comparison on pH measurement and the fifth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006, APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011 and APMP.QM-K19/APMP.QM-P25 (a borate buffer) in 2013-2014. The results can be used further by any participant to support its CMC claim at least for a phthalate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Host plasma proteins on the surface of pathogenic Trichomonas vaginalis.

PubMed

Peterson, K M; Alderete, J F

1982-08-01

Sodium dodecyl sulfate-gel electrophoresis and fluorography and fluorography technology revealed that pathogenic Trichomonas vaginalis was able to acquire numerous loosely associated plasma proteins during incubation in normal human plasma. These proteins were readily removed by repeated washing of the parasite in phosphate-buffered saline. Plasma proteins avidly bound to the surface of T. vaginalis were also detected using a highly sensitive and specific agglutination assay with protein A-bearing Staphylococcus aureus pretreated with monospecific antiserum directed against individual human serum proteins. These avidly associated plasma proteins could not be removed by repeated washing in phosphate-buffered saline or by treatment of washed, live organisms with surface-modifying reagents such as trypsin and periodate. A combined radioimmunoprecipitation-gel electrophoresis-fluorography methodology indicated that parasite biosynthesis of hostlike macromolecules was not responsible for the observed agglutination and reinforced the idea of trichosomal acquisition of plasma components. Finally, incubation of trichomonads with plasma in various buffers at different pH values did not alter the agglutination patterns. These and other data suggest that specific membrane sites trichomonal binding of host proteins. The biological significance of our results is discussed.

Iodine susceptibility of pseudomonads grown attached to stainless steel surfaces

NASA Technical Reports Server (NTRS)

Pyle, B. H.; McFeters, G. A.

1990-01-01

Pseudomonads were adapted to grow in phosphate-buffered water and on stainless steel surfaces to study the iodine sensitivity of attached and planktonic cells. Cultures adapted to low nutrient growth were incubated at room temperature in a circulating reactor system with stainless steel coupons to allow biofilm formation on the metal surfaces. In some experiments, the reactor was partially emptied and refilled with buffer at each sampling time to simulate a "fill-and-draw" water system. Biofilms of attached bacteria, resuspended biofilm bacteria, and reactor suspension, were exposed to 1 mg l-1 iodine for 2 min. Attached bacterial populations which established on coupons within 3 to 5 days displayed a significant increase in resistance to iodine. Increased resistance was also observed for resuspended cells from the biofilm and planktonic bacteria in the system suspension. Generally, intact biofilms and resuspended biofilm cells were most resistant, followed by planktonic bacteria and phosphate buffer cultures. Thus, biofilm formation on stainless steel surfaces within water systems can result in significantly increased disinfection resistance of commonly-occurring water-borne bacteria that may enhance their ability to colonise water treatment and distribution systems.

Influence of phosphate on toxicity and bioaccumulation of arsenic in a soil isolate of microalga Chlorella sp.

PubMed

Bahar, Md Mezbaul; Megharaj, Mallavarapu; Naidu, Ravi

2016-02-01

In this study, the toxicity, biotransformation and bioaccumulation of arsenite and arsenate in a soil microalga, Chlorella sp., were investigated using different phosphate levels. The results indicated that arsenate was highly toxic than arsenite to the alga, and the phosphate limitation in growth media greatly enhanced arsenate toxicity. The uptake of arsenate in algal cells was more than that of arsenite, and the predominant species in the growth media was arsenate after 8 days of exposure to arsenite or arsenate, indicating arsenite oxidation by this microalga. Arsenate reduction was also observed when the alga was incubated in a phosphate-limiting growth medium. Similar to the process of biotransformation, the alga accumulated more arsenic when it was exposed to arsenate and preferably more in a phosphate-limiting condition. Although phosphate significantly influences the biotransformation and bioaccumulation of arsenic, the oxidizing ability and higher accumulation capacity of this alga have great potential for its application in arsenic bioremediation.

Apoenzyme of aspartate aminotransferase isozymes in serum and its diagnostic usefullness for hepatic diseases.

PubMed

Kamei, S; Ohkubo, A; Yamanaka, M

1979-08-15

Aspartate aminotransferase in the sera of normal subjects and of patients with hepatic diseases has been immunologically separated into two isoenzymes, cytosolic aspartate aminotransferase and mitochondrial aspartate aminotransferase. The activity of the isoenzymes was measured in three different buffer solutions with or without pyridoxal 5'-phosphate. To attain maximal activation, the apoenzyme of mitochondrial fraction must be preincubated with pyridoxal 5'-phosphate longer than that of the cytosolic fraction in either of the three reaction mixtures. In most sera the activity of both isoenzymes increased substantially in the presence of pyridoxal 5'-phosphate regardless of the type of buffer solutions. Both the apoenzymatic activity and the ratio of apo- to holo-enzymatic activity of each of the isoenzymes varied among samples from the patients with hepatic diseases. However, significantly high ratios of apo- to holo-enzymatic activity of both isoenzymes were observed in the patients with hepatoma in contrast with those with other hepatic diseases. These findings suggest that the simultaneous measurement of both apo- and holo-enzyme activities of aspartate aminotransferase isoenzymes may be useful in the clinical assessment of hepatic diseases.

Simultaneous pollutant removal and electricity generation in denitrifying microbial fuel cell with boric acid-borate buffer solution.

PubMed

Chen, Gang; Zhang, Shaohui; Li, Meng; Wei, Yan

2015-01-01

A double-chamber denitrifying microbial fuel cell (MFC), using boric acid-borate buffer solution as an alternative to phosphate buffer solution, was set up to investigate the influence of buffer solution concentration, temperature and external resistance on electricity generation and pollutant removal efficiency. The result revealed that the denitrifying MFC with boric acid-borate buffer solution was successfully started up in 51 days, with a stable cell voltage of 205.1 ± 1.96 mV at an external resistance of 50 Ω. Higher concentration of buffer solution favored nitrogen removal and electricity generation. The maximum power density of 8.27 W/m(3) net cathodic chamber was obtained at a buffer solution concentration of 100 mmol/L. An increase in temperature benefitted electricity generation and nitrogen removal. A suitable temperature for this denitrifying MFC was suggested to be 25 °C. Decreasing the external resistance favored nitrogen removal and organic matter consumption by exoelectrogens.

Phosphorus Amendment Efficacy for In Situ Remediation of ...

EPA Pesticide Factsheets

A validated method is needed to measure reductions of in vitro bioaccessible (IVBA) Pb in urban soil remediated with amendments. This study evaluated the effect of in vitro extraction solution pH and glycine buffer on bioaccesible Pb in P-treated soils. Two Pb-contaminated soils (790-1300 mg Pb kg-1), one from a garden and one from a city lot in Cleveland, OH, were incubated in a bench scale experiment for 1 yr. Six phosphate amendments, including bone meal, fish bone, poultry litter, monoammonium phosphate, diammonium phosphate, and triple superphosphate, were added to containers at two application rates. Lead IVBA was assessed using USEPA Method 1340 and three modified versions of this method. Modifications included using solutions with pH 1.5 and 2.5 as well as using solutions with and without 0.4 mol L-1 glycine. Soil amendments were effective in reducing IVBA Pb in these soils as measured by pH 1.5 with glycine buffer. The greatest reductions in IVBA Pb, from 5 to 26%, were found using pH 2.5 extractions. Lead mineral results showed several soil amendments promoted Pb phosphate formation, an indicator of remediation success. A significant negative linear relationship between reduction in IVBA Pb and Pb-phosphate formation was found only for pH 2.5 without glycine extraction solution. A modified USEPA Method 1340 without glycine and using pH 2.5 has the potential to predict P soil treatment efficacy and reductions in bioavailable Pb. Developing mana

Characterization of the phosphate-specific transport system in Cronobacter sakazakii BAA-894.

PubMed

Liang, X; Hu, X; Wang, X; Wang, J; Fang, Y; Li, Y

2017-09-01

Characterize the phosphate-specific transport system in Cronobacter sakazakii BAA-894. The genes relevant to phosphate transfer in C. sakazakii BAA-894 were determined by using sequence alignment to the corresponding genes in Escherichia coli. Then, the determined pst operon in C. sakazakii BAA-894 was deleted using the lambda Red recombination system. Using the wild type C. sakazakii BAA-894 as a control, the membrane permeability, auto-aggregation, exopolysaccharide biosynthesis, biofilm formation, and adhesion ability of the mutant ▵pst grown in media containing high or low concentrations of phosphate were investigated; stronger auto-aggregation, less biofilm formation and higher adhesion ability were observed in ▵pst cells grown in low phosphate media. Transcriptome analysis showed that phosphate availability has a global influence to C. sakazakii BAA-894 and ▵pst cells. Phosphorus availability is important for C. sakazakii in many ways including biofilm formation and adhesion ability. This study demonstrates that phosphate availability has a global influence to C. sakazakii, expends our understanding to the phosphate transfer in C. sakazakii, and is helpful for revealing the survival mechanism of C. sakazakii under stress conditions. © 2017 The Society for Applied Microbiology.

Survival of spumavirus, a primate retrovirus, in laboratory media and water.

PubMed

Lotlikar, Madhavi S; Lipson, Steven M

2002-06-04

The persistence of a previously characterized spumavirus strain (strain SV-522) was investigated utilizing various laboratory media and waters, including Eagle's minimal essential medium (EMEM) plus 0% fetal bovine serum (EMEM-0%), EMEM-2%, EMEM-10%, Chlamydia transport medium (CTM), phosphate-buffered saline, distilled, estuarine, and marine water, human serum, and the germicides, ethyl alcohol (70%) and sodium hypochlorite (10%). Experiments were performed at 4 degrees C and/or 23 degrees C. Infectivity endpoints were determined in stock aliquots upon initiation of testing and then after 3, 5, 7, and 10 days. The virus was reisolated from all diluents after 5 days at 23 degrees C and in EMEM-10% after 7 days. The virus was detected in CTM, EMEM-2%, EMEM-10%, and estuarine and marine waters after 7 days at 4 degrees C. Differences in the persistence of the virus may be ascribed to temperature and organic load. Water ionic strengths (e.g., estuarine vs. marine water) had no effect on modifying persistence of viral particles. Infectivity of spumavirus was undetectable after 30 s in 70% ethanol or 10% sodium hypochlorite. After 30 min at 23 degrees C, spumavirus infectivity in normal but not heat-inactivated human serum increased by almost 100-fold. Persistence of infectivity of primate spumavirus after 7 days in media and waters, and the agent's infectious potential in the human host, emphasize a need for cautious recognition during the manipulation of primate cells/organs and in the handling of primates themselves.

A comparison of dispersing media for various engineered carbon nanoparticles.

PubMed

Buford, Mary C; Hamilton, Raymond F; Holian, Andrij

2007-07-27

With the increased manufacture and use of carbon nanoparticles (CNP) there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others), and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. In this work, the distributions of different CNP (sources and types) have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle.

Lactose/whey utilization and ethanol production by transformed Saccharomyces cerevisiae cells.

PubMed

Porro, D; Martegani, E; Ranzi, B M; Alberghina, L

1992-04-05

Strains of Saccharomyces cerevisiae transformed with a multicopy expression vector bearing both the Escherichia coli beta-galactosidase gene under the control of the upstream activating sequence of the GAL1-10 genes and the GAL4 activator gene release part of beta-galactosidase in the growth medium. This release is due to cell lysis of the older mother cells; the enzyme maintains its activity in buffered growth media. Fermentation studies with transformed yeast strains showed that the release of beta-galactosidase allowed an efficient growth on buffered media containing lactose as carbon source as well as on whey-based media. The transformed strains utilized up to 95% of the lactose and a high growth yield was obtained in rich media. High productions of ethanol were also observed in stationary phase after growth in lactose minimal media.

Functional Analysis of Human NF1 in Drosophila

DTIC Science & Technology

2007-01-01

adjusted to 1 mg/ml. Fifty microlitres of 2 assay buffer (50 mM Tris– acetate buffer at pH 7.5, 20 mM MgCl2, 2 mM dithiothreitol, 10 mM creatine phosphate...200 units/ml creatinine kinase, 0.1 mM cAMP at pH 7.5, 0.2 mg/ml bovine serum albumin, 0.02 mg/ml aprotinin, 0.02 mg/ml pepstatin and fresh 0.2 mg

Live Attenuated Influenza Virus Increases Pneumococcal Translocation and Persistence Within the Middle Ear

PubMed Central

Mina, Michael J.; Klugman, Keith P.; Rosch, Jason W.; McCullers, Jonathan A.

2015-01-01

Background. Infection with influenza A virus (IAV) increases susceptibility to respiratory bacterial infections, resulting in increased bacterial carriage and complications such acute otitis media, pneumonia, bacteremia, and meningitis. Recently, vaccination with live attenuated influenza virus (LAIV) was reported to enhance subclinical bacterial colonization within the nasopharynx, similar to IAV. Although LAIV does not predispose to bacterial pneumonia, whether it may alter bacterial transmigration toward the middle ear, where it could have clinically relevant implications, has not been investigated. Methods. BALB/c mice received LAIV or phosphate-buffered saline 1 or 7 days before or during pneumococcal colonization with either of 2 clinical isolates, 19F or 7F. Middle ear bacterial titers were monitored daily via in vivo imaging. Results. LAIV increased bacterial transmigration to and persistence within the middle ear. When colonization followed LAIV inoculation, a minimum LAIV incubation period of 4 days was required before bacterial transmigration commenced. Conclusions. While LAIV vaccination is safe and effective at reducing IAV and coinfection with influenza virus and bacteria, LAIV may increase bacterial transmigration to the middle ear and could thus increase the risk of clinically relevant acute otitis media. These data warrant further investigations into interactions between live attenuated viruses and naturally colonizing bacterial pathogens. PMID:25505300

W/O/W multiple emulsions containing nitroimidazole derivates for vaginal delivery.

PubMed

Ozer, Ozgen; Ozyazici, Mine; Tedajo, Muriel; Taner, Memduh S; Köseoglu, Kamil

2007-03-01

The aim of our study was to formulate a stable multiple emulsions containing two nitroimidazole derivates, metronidazole (MT) and ornidazole (OR), for vaginal therapy. MT and OR were located internal and external phases of multiple emulsion, respectively, and the in vitro release studies were realized in phosphate (pH 7) and lactate buffer (pH 4.5) solutions to investigate better the effect of pH and location of active substance on the release. The imaging studies were realized in rabbits following labeling MT and OR with Technethium-99m ((99m)Tc) to evaluate the in vivo absorption characteristics. The percentage of MT and OR released from the multiple emulsions in alkaline media were 3.2- and 2.8-fold greater than that observed in acidic media, respectively, when they were introduced in the internal phase of the multiple emulsions. The absorption rate of MT from vaginal epithelium was faster than OR. We observed that especially in alkaline medium a high release was found that was convenient for the vaginal infections seen in the alkaline pH. We concluded that W/O/W multiple emulsions were locally effective in vagina and they could be introduced as a new drug carrier system for vaginal delivery.

A self-powered kinesin-microtubule system for smart cargo delivery

NASA Astrophysics Data System (ADS)

Jia, Yi; Dong, Weiguang; Feng, Xiyun; Li, Jieling; Li, Junbai

2014-11-01

A smart self-powered cargo delivery system that is composed of creatine phosphate kinase (CPK) microspheres, kinesins and microtubules is demonstrated. The CPK microsphere not only acts as an ATP generation and buffering system, but also as a carrier for cargo transport, thus realizing the easy loading and self-powered delivery of cargos at the same time.A smart self-powered cargo delivery system that is composed of creatine phosphate kinase (CPK) microspheres, kinesins and microtubules is demonstrated. The CPK microsphere not only acts as an ATP generation and buffering system, but also as a carrier for cargo transport, thus realizing the easy loading and self-powered delivery of cargos at the same time. Electronic supplementary information (ESI) available: Experimental details, Fig. S1-S4, and Mov. S1-S6. See DOI: 10.1039/c4nr04454a

Electrochemical Behavior of Pure Copper in Phosphate Buffer Solutions: A Comparison Between Micro- and Nano-Grained Copper

NASA Astrophysics Data System (ADS)

Imantalab, O.; Fattah-alhosseini, A.; Keshavarz, M. K.; Mazaheri, Y.

2016-02-01

In this work, electrochemical behavior of annealed (micro-) and nano-grained pure copper (fabricated by accumulative roll bonding process) in phosphate buffer solutions of various pH values ranging from 10.69 to 12.59 has been studied. Before any electrochemical measurements, evaluation of microstructure was obtained by optical microscope and transmission electron microscopy. To investigate the electrochemical behavior of the samples, the potentiodynamic polarization, Mott-Schottky analysis, and electrochemical impedance spectroscopy (EIS) were carried out. Potentiodynamic polarization plots and EIS measurements revealed that as a result of grain refinement, the passive behavior of the nano-grained sample was improved compared to that of annealed pure copper. Also, Mott-Schottky analysis indicated that the passive films behaved as p-type semiconductors and grain refinement did not change the semiconductor type of passive films.

Inactivation of avirulent Yersinia pestis in Butterfield's phosphate buffer and frankfurters by UVC (254 nm) and gamma radiation.

PubMed

Sommers, Christopher H; Cooke, Peter H

2009-04-01

Yersinia pestis is the causative agent of plague. Although rare, pharyngeal plague in humans has been associated with consumption or handling of meat prepared from infected animals. The risks of contracting plague from consumption of deliberately contaminated food are currently unknown. Gamma radiation is a penetrating form of electromagnetic radiation, and UVC radiation is used for decontamination of liquids or food surfaces. Gamma radiation D10-values (the radiation dose needed to inactivate 1 log unit pathogen) were 0.23 (+/-0.01) and 0.31 (+/-0.03) kGy for avirulent Y. pestis inoculated into Butterfield's phosphate buffer and onto frankfurter surfaces, respectively, at 0 degree C. A UVC radiation dose of 0.25 J/cm2 inactivated avirulent Y. pestis suspended in Butterfield's phosphate buffer. UVC radiation doses of 0.5 to 4.0 J/cm2 inactivated 0.97 to 1.20 log units of the Y. pestis surface inoculated onto frankfurters. A low gamma radiation dose of 1.6 kGy could provide a 5-log reduction and a UVC radiation dose of 1 to 4 J/cm2 would provide a 1-log reduction of Y. pestis surface inoculated onto frankfurters. Y. pestis was capable of growth on frankfurters during refrigerated storage (10 degrees C). Gamma radiation of frankfurters inhibited the growth of Y. pestis during refrigerated storage, and UVC radiation delayed the growth of Y. pestis.

Fracture toughness and fractography of dental cements, lining, build-up, and filling materials.

PubMed

Mueller, H J

1990-06-01

The plane strain fracture toughness (K1c) at 23 degrees C and the fractography of zinc phosphate and zinc polycarboxylate cements, buffered glass ionomer liner, amalgam alloy admixed glass ionomer build-up material, and glass ionomer, microfilled and conventionally filled bis-GMA resin composite filling materials were analyzed by elastic-plastic short-rod and scanning electron microscopy methodologies. Results indicated that significant differences occurred in their K1c's from the lowest to the highest in the following groups of materials, (i) buffered glass ionomer, (ii) zinc phosphate, glass ionomer, zinc polycarboxylate, and alloy mixed glass ionomer, (iii) microfilled resin, and (iv) conventionally filled resin. All materials except the microfilled resin, which fractured via crack jumping, fractured via smooth crack advance. Filler debonding without any crack inhibiting process was related to materials with low K1c values. The incorporation of either buffering compounds or alloy particles into glass ionomer had no beneficial effect upon fracture toughness. This was in contrast to microfilled and conventionally filled resins where either crack blunting or crack pinning processes, respectively, were likely involved with their increased K1c's. For microfilled resin, distinct radial zones positioned around the chevron apex and characterized by plastically deformed deposited material were related to distinct crack jumps that occurred in the load versus displacement behavior. Finally, for the two remaining materials of zinc phosphate and polycarboxylate, particle cleavage and matrix debonding for the former and shear yielding for the latter occurred.

High-performance liquid chromatography method for the simultaneous determination of sulfamethoxazole and trimethoprim in bovine milk using an on-line clean-up column.

PubMed

Pereira, A V; Cass, Q B

2005-11-05

A bidimensional HPLC method for the simultaneous determination of sulfamethoxazole (SMX) and trimethoprim (TMP) in bovine milk has been developed and validated. After centrifugation, aliquots (150 microl) of milk samples were directly injected to a column-switching HPLC system. At the first step a RAM octyl-BSA column was employed to automatically remove proteins that otherwise would interfere with milk analysis. The mobile phase 0.01 M phosphate buffer pH 6.0:acetonitrile (95:5, v/v) was used in the first 5 min for the elution of milk proteins and then 0.01 M phosphate buffer pH 6.0:acetonitrile (83:17, v/v) for transfer SMX and TMP to the analytical column. The separation of SMX and TMP from one another and from other remaining milk components was performed on an octyl column using the mobile phase 0.01 M phosphate buffer pH 5.0:acetonitrile (82:18, v/v), which were detected by UV at 265 nm. The calibration graphs were linear in the concentration ranges of 25-800 ng/ml and 50-400 ng/ml for SMX and TMP, respectively. The intra- and inter-assay coefficients of variation were less than 15% for both drugs. The validated method was applied to the analysis of milk samples of twelve (two groups of six) cows after administration (intramuscular or subcutaneous) of a single recommended therapeutic dose of the SMX-TMP combination.

Steel Slag and Shredded Tires as Media for Blind Inlets to Improve Water Quality

NASA Astrophysics Data System (ADS)

Gonzalez, J. M.; Smith, D. R.; Livingston, S.

2015-12-01

Off-site transport of contaminants through surface runoff affects water quality. Blind inlets are proven conservation practices for reducing surface runoff, and consequently reducing nutrient loadings from small agricultural closed depressions to water bodies. Gravel is the most widely used blind inlet media to reduce flow, but not to sorb contaminants from the water. Readily available byproducts, such as steel slag and shredded tires, could be used as alternative media in blind inlets to sorb nutrients and pesticides from surface runoff. Sorption isotherms were performed to investigate the sorption capabilities of steel slag and shredded tires for phosphate and atrazine in electrolyte background solutions containing either 10 mM CaCl2 or KCl. Results of this research demonstrated that phosphate and atrazine were irreversibly sorbed by the steel slag and shredded tires. The steel slag increased the pH solution increased about 4 pH units after the sorption step; while the pH of the solution with shredded tires remained the same. Desorption of the phosphate and atrazine was low from the steel slag and shredded tires, respectively. Thus, the above results suggest that the steel slag and shredded tires can potentially be used as media to sorb phosphate and atrazine, respectively.

Common stock solutions, buffers, and media.

PubMed

2001-05-01

This section describes the preparation of buffers and reagents used in this manual for cell culture, manipulation of tissue, and cell biological methods. Also discussed are special considerations for PCR experiments and for working with RNA.

Phosphate adsorption using modified iron oxide-based sorbents

EPA Pesticide Factsheets

Phosphate RemovalThis dataset is associated with the following publication:Lalley , J., C. Han , G. RamMohan , T. Speth , J. Garland , M. Nadagouda , and D. Dionysiou. Phosphate Removal using Modified Bayoxide®E33 Adsorption Media. WATER RESEARCH. Elsevier Science Ltd, New York, NY, USA, issue}: 96-107, (2015).

Purification of peroxidase from Horseradish (Armoracia rusticana) roots.

PubMed

Lavery, Christopher B; Macinnis, Morgan C; Macdonald, M Jason; Williams, Joanna Bassey; Spencer, Colin A; Burke, Alicia A; Irwin, David J G; D'Cunha, Godwin B

2010-08-11

Peroxidase (EC 1.11.1.7) from horseradish ( Armoracia rusticana ) roots was purified using a simple, rapid, three-step procedure: ultrasonication, ammonium sulfate salt precipitation, and hydrophobic interaction chromatography on phenyl Sepharose CL-4B. The preparation gave an overall yield of 71%, 291-fold purification, and a high specific activity of 772 U mg(-1) protein. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that the purified enzyme was homogeneous and had a molecular weight of approximately 40 kDa. The isolated enzyme had an isoelectric point of 8.8 and a Reinheitszahl value of 3.39 and was stable when stored in the presence of glycerol at -20 degrees C, with >95% retention of original enzyme activity for at least 6 months. Maximal activity of purified horseradish peroxidase (HRP) was obtained under different optimized conditions: substrate (guaiacol and H(2)O(2)) concentrations (0.5 and 0.3 mM, respectively), type of buffer (50 mM phosphate buffer), pH (7.0), time (1.0 min), and temperature of incubation (30 degrees C). In addition, the effect of HRP and H(2)O(2) in a neutral-buffered aqueous solution for the oxidation of phenol and 2-chlorophenol substrates was also studied. Different conditions including concentrations of phenol/2-chlorophenol, H(2)O(2), and enzyme, time, pH, and temperature were standardized for the maximal activity of HRP with these substrates; under these optimal conditions 89.6 and 91.4% oxidations of phenol and 2-chlorophenol were obtained, respectively. The data generated from this work could have direct implications in studies on the commercial production of this biotechnologically important enzyme and its stability in different media.

Comparative Toxicity of Preservatives on Immortalized Corneal and Conjunctival Epithelial Cells

PubMed Central

Ahdoot, Michael; Marcus, Edward; Asbell, Penny A.

2009-01-01

Abstract Purpose Nearly all eye drops contain preservatives to decrease contamination. Nonpreservatives such as disodium-ethylene diamine tetra-acetate (EDTA) and phosphate-buffered saline are also regularly added as buffering agents. These components can add to the toxicity of eye drops and cause ocular surface disease. To evaluate the potential toxicity of these common components and their comparative effects on the ocular surface, a tissue culture model utilizing immortalized corneal and conjunctival epithelial cells was utilized. Methods Immortalized human conjunctival and corneal epithelial cells were grown. At confluency, medium was replaced with 100 μL of varying concentrations of preservatives: benzalkonium chloride (BAK), methyl paraben (MP), sodium perborate (SP), chlorobutanol (Cbl), and stabilized thimerosal (Thi); varying concentrations of buffer: EDTA; media (viable control); and formalin (dead control). After 1 h, solutions were replaced with 150 μL of MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazonium bromide). After 4 h, solutions decanted, 100 μL of acid isopropanol added, and the optical density determined at 572 nm to evaluate cell viability. Results Conjunctival and corneal cell toxicity was seen with all preservatives. Depending upon concentration, BAK exhibited from 56% to 89% toxicity. In comparison, Cbl exhibited from 50% to 86%, MP from 30% to 76%, SP from 23% to 59%, and Thi from 70% to 95%. EDTA with minimal toxicity (from 6% to 59%) was indistinguishable from SP. Conclusions Generally, the order of decreasing toxicity at the most commonly used concentrations: Thi (0.0025%) > BAK (0.025%) > Cbl (0.25%) > MP (0.01%) > SP (0.0025%) ≈ EDTA (0.01%). Even at low concentration, these agents will cause some degree of ocular tissue damage. PMID:19284328

Myricetin solid lipid nanoparticles: Stability assurance from system preparation to site of action.

PubMed

Gaber, Dina M; Nafee, Noha; Abdallah, Osama Y

2017-11-15

Myricetin - a natural flavonoid - has attracted a great interest due to its antioxidant and free-radical scavenging potential. However, its physicochemical instability critically impairs its dosage form design, evaluation and administration. In an attempt to protect from degradation, MYR was encapsulated into Gelucire-based solid lipid nanoparticles (SLNs). The impact of medium pH, processing temperature and different additives on the drug degradation either in free or nanoencapsulated form was assessed. MYR stability was further monitored in essential biorelevant fluids. Investigations have led to the recommendation that the presence of fat-soluble antioxidant is necessary during SLN preparation to protect the drug at high temperature. Meanwhile, physiological buffers as well as simulated fluids should be supplemented with stabilizers as tween 80 and Poloxamer 407, in addition to water-soluble antioxidant such as sodium sulfite. Interestingly, mucin-containing fluids are suggested to provide better protection to MYR, in contrast, cell culture media do not guarantee MYR stability. The degradation kinetics changed from 1st to 2nd order mechanism after MYR nanoencapsulation. In presence of the aforementioned additives, MYR-SLNs significantly reduced the drug degradation rate constant up to 300-folds and prolonged the half-life time up to 4500-folds compared to free MYR in physiological buffers (One-way ANOVA, p<0.05). As a proof of concept, in vitro release experiment in presence of phosphate buffer (pH7.4) supplemented with these additives ensured sustained release of MYR over >8h with no signs of degradation. The study emphasizes virtuous guidance regarding appropriate nanoencapsulation conditions and evaluation attributes ensuing MYR physicochemical stability. Copyright © 2017. Published by Elsevier B.V.

Dependency of plasmon resonance sensitivity of colloidal gold nanoparticles on the identity of surrounding ionic media

NASA Astrophysics Data System (ADS)

Mehrdel, B.; Aziz, A. Abdul

2018-03-01

The plasmon resonance sensitivity of gold nanoparticles (AuNPs) in sodium chloride (NaCl) liquid in near-infrared to the visible spectral region was investigated. The correlation between NaCl concentration and refractive index was analyzed using concentration dependency and Lorenz-Lorenz methods. The first derivative method was applied to the measured absorption spectra to quantitatively evaluate the plasmon resonance sensitivity. To understand the influence of the identity of the surrounding medium on the plasmon resonance sensitivity, experiments were repeated by replacing NaCl with sodium hydroxide (NaOH), followed by phosphate buffered saline (PBS). Experimental results showed that NaCl is the most effective ionic surrounding medium, which gives prominent plasmon resonance response. AuNPs size can have a significant influence on the plasmon resonance sensitivity. For tiny AuNPs (∼10 nm AuNPs), the plasmon resonance is insensitive to the identity of the surrounding medium due to their low cross-section value.

INACTIVATION OF HEPATITIS A VIRUS AND MS2 BY OZONE AND OZONE-HYDROGEN PEROXIDE IN BUFFERED WATER

EPA Science Inventory

The comparative inactivation of highly purified hepatitis A virus (HAV) and MS2 by 1 mg H202/L, 2.0 and 0.4 mg 03/L, and 2.0 mg 03/L plus 0.6, 1.0, or 1.6 mg H202/L, at 3-10 degrees C, in 0.01 M phosphate buffer (pH 6-10) was determined. Both HAV and MS2 were completely inactivat...

Solid-phase extraction of small biologically active peptides on cartridges and microelution 96-well plates from human urine.

PubMed

Semenistaya, Ekaterina; Zvereva, Irina; Krotov, Grigory; Rodchenkov, Grigory

2016-09-01

Currently liquid chromatography - mass spectrometry (LC-MS) analysis after solid-phase extraction (SPE) on weak cation-exchange cartridges is a method of choice for anti-doping analysis of small bioactive peptides such as growth hormone releasing peptides (GHRPs), desmoporessin, LHRH, and TB-500 short fragment. Dilution of urine samples with phosphate buffer for pH adjustment and SPE on weak cation exchange microelution plates was tested as a means to increase throughput of this analysis. Dilution using 200 mM phosphate buffer provides good buffering capacity without affecting the peptides recoveries. SPE on microelution plates was performed on Waters Positive Pressure-96 Processor with subsequent evaporation of eluates in nitrogen flow. Though the use of smaller sample volume decreases the pre-concentration factor and increases the limits of detection of 5 out of 17 detected peptides, the recovery, linearity, and reproducibility of the microelution extraction were comparable with cartridge SPE. The effectiveness of protocols was confirmed by analysis of urine samples containing ipamorelin, and GHRP-6 and its metabolites. SPE after urine sample dilution with buffer can be used for faster sample preparation. The use of microelution plates decreases consumption of solvents and allows processing of up to 96 samples simultaneously. Cartridge SPE with manual рН adjustment remains the best option for confirmation. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Preparation and properties of BSA-loaded microspheres based on multi-(amino acid) copolymer for protein delivery

PubMed Central

Chen, Xingtao; Lv, Guoyu; Zhang, Jue; Tang, Songchao; Yan, Yonggang; Wu, Zhaoying; Su, Jiacan; Wei, Jie

2014-01-01

A multi-(amino acid) copolymer (MAC) based on ω-aminocaproic acid, γ-aminobutyric acid, L-alanine, L-lysine, L-glutamate, and hydroxyproline was synthetized, and MAC microspheres encapsulating bovine serum albumin (BSA) were prepared by a double-emulsion solvent extraction method. The experimental results show that various preparation parameters including surfactant ratio of Tween 80 to Span 80, surfactant concentration, benzyl alcohol in the external water phase, and polymer concentration had obvious effects on the particle size, morphology, and encapsulation efficiency of the BSA-loaded microspheres. The sizes of BSA-loaded microspheres ranged from 60.2 μm to 79.7 μm, showing different degrees of porous structure. The encapsulation efficiency of BSA-loaded microspheres also ranged from 38.8% to 50.8%. BSA release from microspheres showed the classic biphasic profile, which was governed by diffusion and polymer erosion. The initial burst release of BSA from microspheres at the first week followed by constant slow release for the next 7 weeks were observed. BSA-loaded microspheres could degrade gradually in phosphate buffered saline buffer with pH value maintained at around 7.1 during 8 weeks incubation, suggesting that microsphere degradation did not cause a dramatic pH drop in phosphate buffered saline buffer because no acidic degradation products were released from the microspheres. Therefore, the MAC microspheres might have great potential as carriers for protein delivery. PMID:24855351

In-situ polymerisation of fully bioresorbable polycaprolactone/phosphate glass fibre composites: In vitro degradation and mechanical properties.

PubMed

Chen, Menghao; Parsons, Andrew J; Felfel, Reda M; Rudd, Christopher D; Irvine, Derek J; Ahmed, Ifty

2016-06-01

Fully bioresorbable composites have been investigated in order to replace metal implant plates used for hard tissue repair. Retention of the composite mechanical properties within a physiological environment has been shown to be significantly affected due to loss of the integrity of the fibre/matrix interface. This study investigated phosphate based glass fibre (PGF) reinforced polycaprolactone (PCL) composites with 20%, 35% and 50% fibre volume fractions (Vf) manufactured via an in-situ polymerisation (ISP) process and a conventional laminate stacking (LS) followed by compression moulding. Reinforcing efficiency between the LS and ISP manufacturing process was compared, and the ISP composites revealed significant improvements in mechanical properties when compared to LS composites. The degradation profiles and mechanical properties were monitored in phosphate buffered saline (PBS) at 37°C for 28 days. ISP composites revealed significantly less media uptake and mass loss (p<0.001) throughout the degradation period. The initial flexural properties of ISP composites were substantially higher (p<0.0001) than those of the LS composites, which showed that the ISP manufacturing process provided a significantly enhanced reinforcement effect than the LS process. During the degradation study, statistically higher flexural property retention profiles were also seen for the ISP composites compared to LS composites. SEM micrographs of fracture surfaces for the LS composites revealed dry fibre bundles and poor fibre dispersion with polymer rich zones, which indicated poor interfacial bonding, distribution and adhesion. In contrast, evenly distributed fibres without dry fibre bundles or polymer rich zones, were clearly observed for the ISP composite samples, which showed that a superior fibre/matrix interface was achieved with highly improved adhesion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Report of the key comparison APMP.QM-K19. APMP comparison on pH measurement of borate buffer

NASA Astrophysics Data System (ADS)

Hioki, Akiharu; Asakai, Toshiaki; Maksimov, Igor; Suzuki, Toshihiro; Miura, Tsutomu; Obromsook, Krairerk; Tangpaisarnkul, Nongluck; Rodruangthum, Patumporn; Wong, Siu-Kay; Lam, Wai-Hing; Zakaria, Osman; Anuar Mohd. Amin, Khirul; Thanh, Ngo Huy; Máriássy, Michal; Vyskocil, Leos; Hankova, Zuzana; Fisicaro, Paola; Stoica, Daniela; Singh, Nahar; Soni, Daya; Ticona Canaza, Galia; Kutovoy, Viatcheslav; Barbieri Gonzaga, Fabiano; Dias, Júlio Cesar; Vospelova, Alena; Bakovets, Nickolay; Zhanasbayeva, Bibinur

2015-01-01

The APMP.QM-K19 was organised by TCQM of APMP to test the abilities of the national metrology institutes in the APMP region to measure a pH value of a borate buffer. This APMP comparison on pH measurement was proposed by the National Metrology Institute of Japan (NMIJ) and the National Institute of Metrology (Thailand) (NIMT) at the APMP-TCQM meeting held 26-27 November 2012. After approval by TCQM, the comparison has been conducted by NMIJ and NIMT. The comparison is a key comparison following CCQM-K19 and CCQM-K19.1. The comparison material was a borate buffer of pH around 9.2 and the measurement temperatures were 15 °C, 25 °C and 37 °C. This is the second APMP key comparison on pH measurement and the fourth APMP comparison on pH measurement following APMP.QM-P06 (two phosphate buffers) in 2004, APMP.QM-P09 (a phthalate buffer) in 2006 and APMP.QM-K9/APMP.QM-P16 (a phosphate buffer) in 2010-2011. The results can be used further by any participant to support its CMC claim at least for a borate buffer. That claim will concern the pH method employed by the participant during this comparison and will cover the used temperature(s) or the full temperature range between 15°C and 37 °C for the participant which measured pH values at the three temperatures. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Low-density plasma formation in aqueous biological media using sub-nanosecond laser pulses

NASA Astrophysics Data System (ADS)

Genc, Suzanne L.; Ma, Huan; Venugopalan, Vasan

2014-08-01

We demonstrate the formation of low- and high-density plasmas in aqueous media using sub-nanosecond laser pulses delivered at low numerical aperture (NA = 0.25). We observe two distinct regimes of plasma formation in deionized water, phosphate buffered saline, Minimum Essential Medium (MEM), and MEM supplemented with phenol red. Optical breakdown is first initiated in a low-energy regime and characterized by bubble formation without plasma luminescence with threshold pulse energies in the range of Ep ≈ 4-5 μJ, depending on media formulation. The onset of this regime occurs over a very narrow interval of pulse energies and produces small bubbles (Rmax = 2-20 μm) due to a tiny conversion (η < 0.01%) of laser energy to bubble energy EB. The lack of visible plasma luminescence, sharp energy onset, and low bubble energy conversion are all hallmarks of low-density plasma (LDP) formation. At higher pulse energies (Ep = 11-20 μJ), the process transitions to a second regime characterized by plasma luminescence and large bubble formation. Bubbles formed in this regime are 1-2 orders of magnitude larger in size ( R max ≳ 100 μ m ) due to a roughly two-order-of-magnitude increase in bubble energy conversion (η ≳ 3%). These characteristics are consistent with high-density plasma formation produced by avalanche ionization and thermal runaway. Additionally, we show that supplementation of MEM with fetal bovine serum (FBS) limits optical breakdown to this high-energy regime. The ability to produce LDPs using sub-nanosecond pulses focused at low NA in a variety of cell culture media formulations without FBS can provide for cellular manipulation at high throughput with precision approaching that of femtosecond pulses delivered at high NA.

Role of histidine-related compounds to intracellular buffering in fish skeletal muscle.

PubMed

Abe, H; Dobson, G P; Hoeger, U; Parkhouse, W S

1985-10-01

Histidine-related compounds (HRC) were analyzed in fish skeletal muscle as a means of identifying their precise role in intracellular buffering. Fish muscle was used because it contains two functionally and spatially distinct fiber types, red and white. Two fish species, rainbow trout (Salmo gairdneri) and the Pacific blue marlin (Makaira nigricans), were studied because these species demonstrate widely different activity patterns. Marlin red and white muscle buffer capacity was two times higher than trout with white muscle, buffering being two times greater than red in both species. Buffer capacity was highest in the 6.5-7.5 pH range for all tissues, which corresponded to their high anserine levels. The titrated HRC buffering was greater than the observed HRC buffering, which suggested that not all HRC were available to absorb protons. The HRC contribution to total cellular buffering varied from a high of 62% for marlin white to a low of 7% for trout red. The other principal buffers were found to be phosphate and protein with taurine contributing within red muscle in the 7.0-8.0 pH range. HRC were found to be dominant in skeletal muscle buffering by principally accounting for the buffering capacity differences found between the species and fiber types.

Determination of monosaccharides derivatized with 2-aminobenzoic Acid by capillary electrophoresis.

PubMed

Abo, Mitsuru; He, Li-Ping; Sato, Kae; Okubo, Akira

2013-01-01

Reducing monosaccharides were derivatized with 2-aminobenzoic acid (2-AA) through reductive amination using sodium cyanoborohydride as a reductant, and the derivatives were separated by capillary zone electrophoresis with UV detection using 50 mM sodium phosphate (pH 5.5) or 150 mM sodium borate-50 mM sodium phosphate (pH 7.0) running buffer. The derivatives of monosaccharides, which are major components of various carbohydrate materials, were completely separated within 25 min.

Development of a new class of chemical and biological ultrasensors: Ribonuclease contamination and control

NASA Technical Reports Server (NTRS)

1984-01-01

In order to define ribonuclease contamination, an assay for ribonuclease having picogram level sensitivity was established. In this assay, polycytidylic acid is digested by ribonuclease leading to smaller fragments of poly C that remain soluble after treatment of the sample with perchloric acid and lanthanum acetate. An absorbance measurement at 260 nm of the supernatant from the centrifuged sample measures the ribonuclease. A standard curve is shown. Using this assay procedure, ribonuclease contamination was found to be significant in routine laboratory proteins, in particular, bovine serum albumin, lysozyme, catalase, and cytochrome C. This was confirmed by demonstrating a considerable reduction in this activity in the presence of phosphate buffer since phosphate inhibits ribonuclease. Ribonuclease contamination was not significantly encountered in routine laboratory glassware, plasticware, column surfaces, chromatographic particles, and buffer reagents, including airborne contamination. Some contamination could be introduced by fingerprints, however.

Influence of albumin on the electrochemical behaviour of Zr in phosphate buffered saline solutions.

PubMed

Wang, Lu-Ning; Huang, Xian-Qiu; Shinbine, Alyssa; Luo, Jing-Li

2013-02-01

The corrosion behaviour of Zr in phosphate buffered saline (PBS) solutions with various concentrations (0-4 g L(-1)) of albumin was studied by electrochemical techniques and surface analysis. Addition of albumin to PBS solutions moved the open circuit potential (OCP) to less nobler direction. OCP, polarization resistance and impedance increased and the corrosion current decreased over immersion duration. At early stages of immersion, the resistance was increased with the concentration of albumin because of the high adsorption kinetics of albumin on metal. After the long term immersion, the resistance in PBS without albumin was higher than PBS with albumin owing to the anodic dissolution effect of albumin on metal. According to the analysis of effective capacitances, a normal distribution of time-constants was proposed to estimate the surface film on Zr. A corrosion mechanism of Zr in PBS with different albumin was proposed based on electrochemical analysis.

Flexible, Low-Cost Sensor Based on Electrolyte Gated Carbon Nanotube Field Effect Transistor for Organo-Phosphate Detection

PubMed Central

Bhatt, Vijay Deep; Joshi, Saumya; Becherer, Markus; Lugli, Paolo

2017-01-01

A flexible enzymatic acetylcholinesterase biosensor based on an electrolyte-gated carbon nanotube field effect transistor is demonstrated. The enzyme immobilization is done on a planar gold gate electrode using 3-mercapto propionic acid as the linker molecule. The sensor showed good sensing capability as a sensor for the neurotransmitter acetylcholine, with a sensitivity of 5.7 μA/decade, and demonstrated excellent specificity when tested against interfering analytes present in the body. As the flexible sensor is supposed to suffer mechanical deformations, the endurance of the sensor was measured by putting it under extensive mechanical stress. The enzymatic activity was inhibited by more than 70% when the phosphate-buffered saline (PBS) buffer was spiked with 5 mg/mL malathion (an organophosphate) solution. The biosensor was successfully challenged with tap water and strawberry juice, demonstrating its usefulness as an analytical tool for organophosphate detection. PMID:28524071

Synthesis of aldehyde-linked nucleotides and DNA and their bioconjugations with lysine and peptides through reductive amination.

PubMed

Raindlová, Veronika; Pohl, Radek; Hocek, Michal

2012-03-26

5-(5-Formylthienyl)-, 5-(4-formylphenyl)- and 5-(2-fluoro-5-formylphenyl)cytosine 2'-deoxyribonucleoside mono- (dC(R)MP) and triphosphates (dC(R)TP) were prepared by aqueous Suzuki-Miyaura cross-coupling of 5-iodocytosine nucleotides with the corresponding formylarylboronic acids. The dC(R)TPs were excellent substrates for DNA polymerases and were incorporated into DNA by primer extension or PCR. Reductive aminations of the model dC(R)MPs with lysine or lysine-containing tripeptide were studied and optimized. In aqueous phosphate buffer (pH 6.7) the yields of the reductive aminations with tripeptide III were up to 25 %. Bioconjugation of an aldehyde-containing DNA with a lysine-containing tripeptide was achieved through reductive amination in yields of up to 90 % in aqueous phosphate buffer. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Formation of Fluorohydroxyapatite with Silver Diamine Fluoride

PubMed Central

Mei, M.L.; Nudelman, F.; Marzec, B.; Walker, J.M.; Lo, E.C.M.; Walls, A.W.; Chu, C.H.

2017-01-01

Silver diamine fluoride (SDF) is found to promote remineralization and harden the carious lesion. Hydroxyapatite crystallization is a crucial process in remineralization; however, the role of SDF in crystal formation is unknown. We designed an in vitro experiment with calcium phosphate with different SDF concentrations (0.38, 1.52, 2.66, 3.80 mg/mL) to investigate the effect of this additive on the nucleation and growth of apatite crystals. Two control groups were also prepared—calcium phosphate (CaCl2·2H2O + K2HPO4 in buffer solution) and SDF (Ag[NH3]2F in buffer solution). After incubation at 37 oC for 24 h, the shape and organization of the crystals were examined by bright-field transmission electron microscopy and electron diffraction. Unit cell parameters of the obtained crystals were determined with powder X-ray diffraction. The vibrational and rotational modes of phosphate groups were analyzed with Raman microscopy. The transmission electron microscopy and selected-area electron diffraction confirmed that all solids precipitated within the SDF groups were crystalline and that there was a positive correlation between the increased percentage of crystal size and the concentration of SDF. The powder X-ray diffraction patterns indicated that fluorohydroxyapatite and silver chloride were formed in all the SDF groups. Compared with calcium phosphate control, a contraction of the unit cell in the a-direction but not the c-direction in SDF groups was revealed, which suggested that small localized fluoride anions substituted the hydroxyl anions in hydroxyapatite crystals. This was further evidenced by the Raman spectra, which displayed up-field shift of the phosphate band in all the SDF groups and confirmed that the chemical environment of the phosphate functionalities indeed changed. The results suggested that SDF reacted with calcium and phosphate ions and produced fluorohydroxyapatite. This preferential precipitation of fluorohydroxyapatite with reduced solubility could be one of the main factors for arrest of caries lesions treated with SDF. PMID:28521107

Determination of bromhexine in plasma by reversed-phase liquid chromatography. Interference of lipoproteins on extraction.

PubMed

Johansson, M; Lenngren, S

1988-11-18

Extraction of the hydrophobic tertiary amine bromhexine from plasma using cyclohexane-heptafluorobutanol (99.5:0.5, v/v) was studied at different pH values. The extraction yield from buffer solutions was quantitative at pH greater than 4.1, but from plasma the extraction yield decreased with increasing pH. Furthermore, at pH 8.4 the extraction yield varied greatly (56-99%) in different human plasma. The addition of lipoproteins to phosphate buffer, at pH 8.1, decreased the extraction yields considerably. Quantitative extraction from plasma was obtained by using a very long extraction time at pH 8.4 or by decreasing the pH to 5.4. The chromatographic system consisted of a reversed-phase column (Nucleosil C18, 5 microns) with an acidic mobile phase (methanol-phosphate buffer, pH 2) containing an aliphatic tertiary amine. UV detection at 308 or 254 nm was used. The limit of quantitation was 5 ng/ml using 3.00 ml of plasma and detection at 254 nm. The intra-assay precision for bromhexine was better than 3.6% at 5 ng/ml.

ssDNA degradation along capillary electrophoresis process using a Tris buffer.

PubMed

Ric, Audrey; Ong-Meang, Varravaddheay; Poinsot, Verena; Martins-Froment, Nathalie; Chauvet, Fabien; Boutonnet, Audrey; Ginot, Frédéric; Ecochard, Vincent; Paquereau, Laurent; Couderc, François

2017-06-01

Tris-Acetate buffer is currently used in the selection and the characterization of ssDNA by capillary electrophoresis (CE). By applying high voltage, the migration of ionic species into the capillary generates a current that induces water electrolysis. This phenomenon is followed by the modification of the pH and the production of Tris derivatives. By injecting ten times by capillary electrophoresis ssDNA (50 nM), the whole oligonucleotide was degraded. In this paper, we will show that the Tris buffer in the running vials is modified along the electrophoretic process by electrochemical reactions. We also observed that the composition of the metal ions changes in the running buffer vials. This phenomenon, never described in CE, is important for fluorescent ssDNA analysis using Tris buffer. The oligonucleotides are degraded by electrochemically synthesized species (present in the running Tris vials) until it disappears, even if the separation buffer in the capillary is clean. To address these issues, we propose to use a sodium phosphate buffer that we demonstrate to be electrochemically inactive. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Multiprobe Spectroscopic Inverstigation of Molecular-level Behavior within Aqueous 1-Butyl-3-methylimidazolium Tetrafluoroborate

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sarkar, Abhra; Ali, Maroof; Baker, Gary A

2009-01-01

In this work, an array of molecular-level solvent featuressincluding solute-solvent/solvent-solvent interactions, dipolarity, heterogeneity, dynamics, probe accessibility, and diffusionswere investigated across the entire composition of ambient mixtures containing the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate, [bmim][BF4], and pH 7.0 phosphate buffer, based on results assembled for nine different molecular probes utilized in a range of spectroscopic modes. These studies uncovered interesting and unusual solvatochromic probe behavior within this benchmark mixture. Solvatochromic absorbance probessa watersoluble betaine dye (betaine dye 33), N,N-diethyl-4-nitroaniline, and 4-nitroanilineswere employed to determine ET (a blend of dipolarity/polarizability and hydrogen bond donor contributions) and the Kamlet-Taft indices * (dipolarity/polarizability), R (hydrogenmore » bond donor acidity), and (hydrogen bond acceptor basicity) characterizing the [bmim][BF4] + phosphate buffer system. These parameters each showed a marked deviation from ideality, suggesting selective solvation of the individual probe solutes by [bmim][BF4]. Similar conclusions were derived from the responses of the fluorescent polarity-sensitive probes pyrene and pyrene-1-carboxaldehyde. Importantly, the fluorescent microfluidity probe 1,3-bis(1-pyrenyl)propane senses a microviscosity within the mixture that significantly exceeds expectations derived from simple interpolation of the behavior in the neat solvents. On the basis of results from this probe, a correlation between microviscosity and bulk viscosity was established; pronounced solvent-solvent hydrogen-bonding interactions were implicit in this behavior. The greatest deviation from ideal additive behavior for the probes studied herein was consistently observed to occur in the buffer-rich regime. Nitromethane-based fluorescence quenching of pyrene within the [bmim][BF4] + phosphate buffer system showed unusual compliance with a sphere-of-action quenching model, a further manifestation of the microheterogeneity of the system. Fluorescence correlation spectroscopic results for both small (BODIPY FL) and macromolecular (Texas Red-10 kDa dextran conjugate) diffusional probes provide additional evidence in support of microphase segregation inherent to aqueous [bmim][BF4].« less

Evaluation of the pH- and Thermal Stability of the Recombinant Green Fluorescent Protein (GFP) in the Presence of Sodium Chloride

NASA Astrophysics Data System (ADS)

Ishii, Marina; Kunimura, Juliana Sayuri; Jeng, Hélio Tallon; Vessoni Penna, Thereza Christina; Cholewa, Olivia

The thermal stability of recombinant green fluorescent protein (GFP) in sodium chloride (NaCl) solutions at different concentrations, pH, and temperatures was evaluated by assaying the loss of fluorescence intensity as a measure of denaturation. GFP, extracted from Escherichia coli cells by the three-phase partitioning method and purified through a butyl hydrophobic interaction chromatography (HIC) column, was diluted in water for injection (WFI) (pH 6.0-7.0) and in 10 mM buffer solutions (acetate, pH 5.0; phosphate, pH 7.0; and Tris-EDTA, pH 8.0) with 0.9-30% NaCl or without and incubated at 80-95°C. The extent of protein denaturation was expressed as a percentage of the calculated decimal reduction time (D-value). In acetate buffer (pH 4.84 ±0.12), the mean D-values for 90% reduction in GFP fluorescence ranged from 2.3 to 3.6 min, independent of NaCl concentration and temperature. GFP thermal stability diluted in WFI (pH 5.94±0.60) was half that observed in phosphate buffer (pH 6.08±0.60); but in both systems, D-values decreased linearly with increasing NaCl concentration, with D-values (at 80°C) ranging from 3.44, min (WFI) to 6.1 min (phosphate buffer), both with 30% NaCl. However, D-values in Tris-EDTA (pH 7.65±0.17) were directly dependent on the NaCl concentration and 5-10 times higher than D-values for GFP in WFI at 80°C. GFP pH-and thermal stability can be easily monitored by the convenient measure of fluorescence intensity and potentially be used as an indicator to monitor that processing times and temperatures were attained.

Osteogenic differentiation of immature osteoblasts: Interplay of cell culture media and supplements.

PubMed

Brauer, A; Pohlemann, T; Metzger, W

2016-01-01

Differentiation of immature osteoblasts to mature osteoblasts in vitro initially was induced by supplementing the medium with β-gylcerophosphate and dexamethasone. Later, ascorbic acid, vitamin D3, vitamin K3 and TGFβ1 were used in varying concentrations as supplements to generate a mature osteoblast phenotype. We tested the effects of several combinations of cell culture media, seeding protocols and osteogenic supplements on osteogenic differentiation of human primary osteoblasts. Osteogenic differentiation was analyzed by staining alkaline phosphatase (ALP) with 5-bromo-4-chloro-3-indolyl-phosphate/nitro blue tetrazolium (BCIP/NBT) and by von Kossa staining of deposited calcium phosphate. The combinations of culture media and supplements significantly influenced osteogenic differentiation, but the seeding protocol did not. Staining of ALP and calcium phosphate could be achieved only if our own mix of osteogenic supplements was used in combination with Dulbecco's modified Eagle medium or if a commercial mix of osteogenic supplements was used in combination with osteoblast growth medium. Especially for von Kossa, we observed great variations in the staining intensity. Because osteogenic differentiation is a complex process, the origin of the osteoblasts, cell culture media and osteogenic supplements should be established by preliminary experiments to achieve optimal differentiation. Staining of ALP or deposited calcium phosphate should be supplemented with qRT-PCR studies to learn more about the influence of specific supplements on osteogenic markers.

Bioactive calcium phosphate–based glasses and ceramics and their biomedical applications: A review

PubMed Central

Islam, Md Towhidul; Felfel, Reda M; Abou Neel, Ensanya A; Grant, David M; Ahmed, Ifty; Hossain, Kazi M Zakir

2017-01-01

An overview of the formation of calcium phosphate under in vitro environment on the surface of a range of bioactive materials (e.g. from silicate, borate, and phosphate glasses, glass-ceramics, bioceramics to metals) based on recent literature is presented in this review. The mechanism of bone-like calcium phosphate (i.e. hydroxyapatite) formation and the test protocols that are either already in use or currently being investigated for the evaluation of the bioactivity of biomaterials are discussed. This review also highlights the effect of chemical composition and surface charge of materials, types of medium (e.g. simulated body fluid, phosphate-buffered saline and cell culture medium) and test parameters on their bioactivity performance. Finally, a brief summary of the biomedical applications of these newly formed calcium phosphate (either in the form of amorphous or apatite) is presented. PMID:28794848

pH-Dependent Solubility and Dissolution Behavior of Carvedilol--Case Example of a Weakly Basic BCS Class II Drug.

PubMed

Hamed, Rania; Awadallah, Areeg; Sunoqrot, Suhair; Tarawneh, Ola; Nazzal, Sami; AlBaraghthi, Tamadur; Al Sayyad, Jihan; Abbas, Aiman

2016-04-01

The objective of this study was to investigate the pH-dependent solubility and dissolution of weakly basic Biopharmaceutical Classification Systems (BCS) class II drugs, characterized by low solubility and high permeability, using carvedilol, a weak base with a pK a value of 7.8, as a model drug. A series of solubility and in vitro dissolution studies was carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH range of the GI from 1.2 to 7.8. The effect of ionic strength, buffer capacity, and buffer species of the dissolution media on the solubility and dissolution behavior of carvedilol was also investigated. The study revealed that carvedilol exhibited a typical weak base pH-dependent solubility profile with a high solubility at low pH (545.1-2591.4 μg/mL within the pH range 1.2-5.0) and low solubility at high pH (5.8-51.9 μg/mL within the pH range 6.5-7.8). The dissolution behavior of carvedilol was consistent with the solubility results, where carvedilol release was complete (95.8-98.2% released within 60 min) in media simulating the gastric fluid (pH 1.2-5.0) and relatively low (15.9-86.2% released within 240 min) in media simulating the intestinal fluid (pH 6.5-7.8). It was found that the buffer species of the dissolution media may influence the solubility and consequently the percentage of carvedilol released by forming carvedilol salts of varying solubilities. Carvedilol solubility and dissolution decreased with increasing ionic strength, while lowering the buffer capacity resulted in a decrease in carvedilol solubility and dissolution rate.

Hormone-Dependence of Sarin Lethality in Rats: Sex Differences and Stage of the Estrous Cycle

DTIC Science & Technology

2015-06-12

that causes numerous physiological events including miosis, salivation , respiratory failure, tremors, seizures, and death. Treatment regimens that...into 96-well plates. The reactions were initiated by the addition of 290 μL of 50 mM sodium phosphate buffer ( pH 8.0) containing one of the following...buffer containing 50mMHEPES pH 7.4 in a total volume of 280 μL. Treat- ed samples were loaded into a 96-microtiter plate well, and the reaction was

A Core Facility for the Study of Neurotoxins of Biological Origin

DTIC Science & Technology

1990-06-15

toxicity of 5 x 10-8 MLD/mg protein. Sodium 125 Iodine and the Bolton-Hunter Reagent - 1251odine were purchased from Amersham. Chloramine- T , glycine...tyrosine and all salts and buffers were from Sigma Chemical Co. and Fisher. Iodination procedures. The chloramine- T method was used essentially as...previously described. Tetanus toxin (100 ig) in sodium phosphate buffer (100 mM, pH 7.4) was mixed with chloramine- T (0.5 mM) and Na 1251 (1 mCi) for 30

[Isolation and determination of the seeds of Pachyrrhizus errosus protein by high performance gel filtration chromatography (GFC)].

PubMed

Wu, H; Hao, B; Tang, G; Lin, Y

1997-03-01

From the seeds of Pachyrrhizus errosus, three protein constituents, namel PE1, PE2 and PE3, have been isolated and purified by extraction with 5mmol/L phosphate saline (0.9% NaCl) buffer (PB) at pH 7.2, and S-Sepharose Fast Flow Column (2.6cm x 15cm) chromatography which eluted with 5mmol/L phosphate buffer (pH 7.0) containing 1mmol/L NaCl. Three proteins were burther separated on two connected Protein-Pak 60+Protein-Pak 125 [7.5mm x 39cm, 10microm] columns with mobile phase of 0.2mol/L phosphate buffer (pH 6.5). The flow rate was kept constant at 0.8mL/min by YSB-2 type high press pump. The effluent was monitored at a wavelength of 280nm on photodiode array detector. These three proteins are proved to be homogeneous by SDS-PAGE, IEF and HPGFC experiments, and all present the typical absorption spectra in ultraviolet region. The moleculer weights of the three proteins are approxiamtely 33000D, 14500D and 14000D respectively by SDS-PAGE. But as using HPGFC analysis, the MW value of PE2 is 28000D. This indicates PE2 may be composed of two chains joined by disulfide bond, which is further proved from the latter amino acid composition analysis. The isoelectric points of three proteins are 4.5, 6.5 and 7.5 respectively by using IEF. The amion acids compositions of the three proteins were determined with OPA post-column derivatization/fluorescence detection.

Two new glucose 6-phosphate dehydrogenase variants associated with congenital nonspherocytic hemolytic anemia found in Japan: GD(-) Tokushima and GD(-) Tokyo.

PubMed

Miwa, S; Ono, J; Nakashima, K; Abe, S; Kageoka, T

1976-01-01

Two new variants of glucose 6-phosphate dehydrogenase (G6PD) deficiency associated with chronic nonspherocytic hemolytic anemia were discovered in Japan. Gd(-) Tokushima was found in a 17-years-old male whose erythrocytes contained 4.4% of normal enzyme activity. Partially purified enzyme revealed a main band of normal electrophoretic mobility with additional two minor bands of different mobility; normal Km G6P, and Km NADP five-to sixfold higher than normal; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; marked thermal instability; a normal pH curve; and normal Ki NADPH. The hemolytic anemia was moderate to severe. Gd(-) Tokyo was characterized from a 15-year-old male who had chronic nonspherocytic hemolytic anemia of mild degree. The erythrocytes contained 3% of normal enzyme activity, and partially purified enzyme revealed slow electrophoretic mobility (90% of normal for both a tris-hydrochloride buffer system and a tris-EDTA-borate buffer system, and 70% of normal for a phosphate buffer system); normal Km G6P and Km NADP; normal utilization of 2-deoxy-G6P, galactose-6P, and deamino-NADP; greatly increased thermal instability; a normal pH curve; and normal Ki NADPH. These two variants are clearly different from hitherto described G6PD variants, including the Japanese variants Gd(-) Heian and Gd(-) Kyoto. The mothers of both Gd(-) Tokushima and Gd(-) Tokoyo were found to be heterozygote by an ascorbate-cyanide test.

Kinetic behaviour of calf intestinal alkaline phosphatase with pNPP.

PubMed

Chaudhuri, Gouri; Chatterjee, Saswata; Venu-Babu, P; Ramasamy, K; Thilagaraj, W Richard

2013-02-01

The hydrolysis of p-nitrophenyl phosphate (pNPP) by calf intestinal alkaline phosphatase (CIAP) was investigated with respect to kinetic parameters such as V(max), K(m) and K(cat) under varying pH, buffers, substrate concentration, temperature and period of incubation. Highest activity was obtained with Tris-HCl at pH 11, while in the case of glycine-NaOH buffer the peak activity was recorded at pH 9.5. The enzyme showed the following kinetic characteristics with pNPP in 50 mM Tris-HCl at pH 11 and 100 mM glycine-NaOH at pH 9.5 at an incubation temperature of 37 degrees C: V(max), 3.12 and 1.6 micromoles min(-1) unit(-1); K(m), 7.6 x 10(-4) M and 4 x 10(-4) M; and K(cat), 82.98 s(-1) and 42.55 s(-1), respectively. CIAP displayed a high temperature optimum of 45 degrees C at pH 11. The kinetic behaviour of the enzyme under different parameters suggested that the enzyme might undergo subtle conformational changes in response to the buffers displaying unique characteristics. Bioprecipitation of Cu2+ from 50 ppm of CuCl2 solution was studied where 64.3% of precipitation was obtained. P(i) generated from CIAP-mediated hydrolysis of pNPP was found to bind with copper and precipitated as copper-phosphate. Thus, CIAP could be used as a test candidate in bioremediation of heavy metals from industrial wastes through generation of metal-phosphate complexes.

Development and Optimization of HPLC Analysis of Metronidazole, Diloxanide, Spiramycin and Cliquinol in Pharmaceutical Dosage Forms Using Experimental Design.

PubMed

Elkhoudary, Mahmoud M; Abdel Salam, Randa A; Hadad, Ghada M

2016-11-01

A new simple, sensitive, rapid and accurate gradient reversed-phase high-performance liquid chromatography with photodiode array detector (RP-HPLC-DAD) was developed and validated for simultaneous analysis of Metronidazole (MNZ), Spiramycin (SPY), Diloxanidefuroate (DIX) and Cliquinol (CLQ) using statistical experimental design. Initially, a resolution V fractional factorial design was used in order to screen five independent factors: the column temperature (°C), pH, phosphate buffer concentration (mM), flow rate (ml/min) and the initial fraction of mobile phase B (%). pH, flow rate and initial fraction of mobile phase B were identified as significant, using analysis of variance. The optimum conditions of separation determined with the aid of central composite design were: (1) initial mobile phase concentration: phosphate buffer/methanol (50/50, v/v), (2) phosphate buffer concentration (50 mM), (3) pH (4.72), (4) column temperature 30°C and (5) mobile phase flow rate (0.8 ml min -1 ). Excellent linearity was observed for all of the standard calibration curves, and the correlation coefficients were above 0.9999. Limits of detection for all of the analyzed compounds ranged between 0.02 and 0.11 μg ml -1 ; limits of quantitation ranged between 0.06 and 0.33 μg ml -1 The proposed method showed good prediction ability. The optimized method was validated according to ICH guidelines. Three commercially available tablets were analyzed showing good % recovery and %RSD. © The Author 2016. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Effect of Sample Preparation on the Discrimination of Bacterial Isolates Cultured in Liquid Nutrient Media Using Laser-Induced Breakdown Spectroscopy (LIBS).

PubMed

Gamble, Gary R; Park, Bosoon; Yoon, Seung-Chul; Lawrence, Kurt C

2016-03-01

Laser-induced breakdown spectroscopy (LIBS) is used as the basis for discrimination between two genera of gram-negative bacteria and two genera of gram-positive bacteria representing pathogenic threats commonly found in poultry processing rinse waters. Because LIBS-based discrimination relies primarily upon the relative proportions of inorganic cell components including Na, K, Mg, and Ca, this study aims to determine the effects of trace mineral content and pH found in the water source used to isolate the bacteria upon the reliability of the resulting discriminant analysis. All four genera were cultured using tryptic soy agar (TSA) as the nutrient medium, and were grown under identical environmental conditions. The only variable introduced is the source water used to isolate the cultured bacteria. Cultures of each bacterium were produced using deionized (DI) water under two atmosphere conditions, reverse osmosis (RO) water, tap water, phosphate buffered saline (PBS) water, and TRIS buffered water. After 3 days of culture growth, the bacteria were centrifuged and washed three times in the same water source. Bacteria were then freeze dried, mixed with microcrystalline cellulose, and a pellet was made for LIBS analysis. Principal component analysis (PCA) was used to extract related variations in LIBS spectral data among the four bacteria genera and six water types used to isolate the bacteria, and Mahalanobis discriminant analysis (MDA) was used for classification. Results indicate not only that the four genera can be discriminated from each other in each water type, but that each genus can be discriminated by water type used for isolation. It is concluded that in order for LIBS to be a reliable and repeatable method for discrimination of bacteria grown in liquid nutrient media, care must be taken to insure that the water source used in purification of the culture be precisely controlled regarding pH, ionic strength, and proportionate amounts of mineral cations present. © The Author(s) 2016.

31P-Nuclear Magnetic Resonance Determination of Phosphate Compartmentation in Leaves of Reproductive Soybeans (Glycine max L.) as Affected by Phosphate Nutrition 1

PubMed Central

Lauer, Michael J.; Blevins, Dale G.; Sierzputowska-Gracz, Hanna

1989-01-01

Most leaf phosphorus is remobilized to the seed during reproductive development in soybean. We determined, using 31P-NMR, the effect phosphorus remobilization has on vacuolar inorganic phosphate pool size in soybean (Glycine max [L.] Merr.) leaves with respect to phosphorus nutrition and plant development. Phosphate compartmentation between cytoplasmic and vacuolar pools was observed and followed in intact tissue grown hydroponically, at the R2, R4, and R6 growth stages. As phosphorus in the nutrient solution decreased from 0.45 to 0.05 millimolar, the vacuolar phosphate peak became less prominent relative to cytoplasmic phosphate and hexose monophosphate peaks. At a nutrient phosphate concentration of 0.05 millimolar, the vacuolar phosphate peak was not detectable. At higher levels of nutrient phosphate, as plants progressed from the R2 to the R6 growth stage, the vacuolar phosphate peak was the first to disappear, suggesting that storage phosphate was remobilized to a greater extent than metabolic phosphate. Under suboptimal phosphate nutrition (≤ 0.20 millimolar), the hexose monophosphate and cytoplasmic phosphate peaks declined earlier in reproductive development than when phosphate was present in optimal amounts. Under low phosphate concentrations (0.05 millimolar) cytoplasmic phosphate was greatly reduced. Carbon metabolism was coincidently disrupted under low phosphate nutrition as shown by the appearance of large, prominent starch grains in the leaves. Cytoplasmic phosphate, and leaf carbon metabolism dependent on it, are buffered by vacuolar phosphate until late stages of reproductive growth. Images Figure 4 PMID:16666705

Increasing the potency of an alhydrogel-formulated anthrax vaccine by minimizing antigen-adjuvant interactions.

PubMed

Watkinson, Allan; Soliakov, Andrei; Ganesan, Ashok; Hirst, Karie; Lebutt, Chris; Fleetwood, Kelly; Fusco, Peter C; Fuerst, Thomas R; Lakey, Jeremy H

2013-11-01

Aluminum salts are the most widely used vaccine adjuvants, and phosphate is known to modulate antigen-adjuvant interactions. Here we report an unexpected role for phosphate buffer in an anthrax vaccine (SparVax) containing recombinant protective antigen (rPA) and aluminum oxyhydroxide (AlOH) adjuvant (Alhydrogel). Phosphate ions bind to AlOH to produce an aluminum phosphate surface with a reduced rPA adsorption coefficient and binding capacity. However, these effects continued to increase as the free phosphate concentration increased, and the binding of rPA changed from endothermic to exothermic. Crucially, phosphate restored the thermostability of bound rPA so that it resembled the soluble form, even though it remained tightly bound to the surface. Batches of vaccine with either 0.25 mM (subsaturated) or 4 mM (saturated) phosphate were tested in a disease model at batch release, which showed that the latter was significantly more potent. Both formulations retained their potency for 3 years. The strongest aluminum adjuvant effects are thus likely to be via weakly attached or easily released native-state antigen proteins.

A comparison of dispersing media for various engineered carbon nanoparticles

PubMed Central

Buford, Mary C; Hamilton, Raymond F; Holian, Andrij

2007-01-01

Background With the increased manufacture and use of carbon nanoparticles (CNP) there has been increasing concern about the potential toxicity of fugitive CNP in the workplace and ambient environment. To address this matter a number of investigators have conducted in vitro and in vivo toxicity assessments. However, a variety of different approaches for suspension of these particles (culture media, Tween 80, dimethyl sulfoxide, phosphate-buffered saline, fetal calf serum, and others), and different sources of materials have generated potentially conflicting outcomes. The quality of the dispersion of nanoparticles is very dependent on the medium used to suspend them, and this then will most likely affect the biological outcomes. Results In this work, the distributions of different CNP (sources and types) have been characterized in various media. Furthermore, the outcome of instilling the different agglomerates, or size distributions, was examined in mouse lungs after one and seven days. Our results demonstrated that CNP suspended in serum produced particle suspensions with the fewest large agglomerates, and the most uniform distribution in mouse lungs. In addition, no apparent clearance of instilled CNP took place from lungs even after seven days. Conclusion This work demonstrates that CNP agglomerates are present in all dispersing vehicles to some degree. The vehicle that contains some protein, lipid or protein/lipid component disperses the CNP best, producing fewer large CNP agglomerates. In contrast, vehicles absent of lipid and protein produce the largest CNP agglomerates. The source of the CNP is also a factor in the degree of particle agglomeration within the same vehicle. PMID:17655771

Dried venous blood samples for the detection and quantification of measles IgG using a commercial enzyme immunoassay.

PubMed Central

Riddell, Michaela A.; Byrnes, Graham B.; Leydon, Jennie A.; Kelly, Heath A.

2003-01-01

OBJECTIVES: To determine whether samples of dried venous blood (DVB) were an acceptable alternative to serum for detecting measles-specific IgG in a commercial enzyme immunoassay. METHODS: Paired samples of serum and DVB were collected from 98 suspected cases of measles and 1153 schoolchildren in Victoria, Australia. All samples were tested using the Dade Behring Enzygnost Anti-Measles-Virus/IgG immunoassay. DVB samples were eluted using either the sample buffer provided with the kit or 5% dry milk powder in phosphate-buffered saline-Tween 20. FINDINGS: DVB samples eluted by sample buffer showed significantly better linear correlation to the serum samples than did DVB samples eluted in 5% dry milk in phosphate-buffered saline-Tween 20. To improve the comparability of serum and DVB samples an adjustment factor of 1.28 was applied to the optical density (OD) values of DVB. This adjustment also enabled quantification of the titre of measles IgG in mIU/ml directly from the OD value using the alpha calculation as specified by the kit protocol. For DVB samples stored for less than six months at 4 degrees C, the assay showed an overall sensitivity of 98.4% and a specificity of 97.2% compared with the results of serum testing. CONCLUSION: These results illustrate the potential for DVB samples to be widely used with the Dade Behring enzyme immunoassay system for determining the immunity of the individual and the population to the measles virus. PMID:14758429

Fish Viruses: Buffers and Methods for Plaquing Eight Agents Under Normal Atmosphere

PubMed Central

Wolf, Ken; Quimby, M. C.

1973-01-01

A universal procedure was sought for plaque assay of eight fish viruses (bluegill myxovirus, channel catfish virus, eel virus, Egtved virus, infectious hematopoietic necrosis virus, infectious pancreatic necrosis virus, lymphocystis virus, and the agent of spring viremia of carp (Rhabdovirus carpio), in dish cultures of various fish cells. Eagle minimal essential medium with sodium bicarbonate-CO2 buffer (Earle’s salt solution) was compared with minimal essential medium buffered principally with tris (hydroxymethyl)aminomethane or N-2-hydroxyethylpiperazine-N′-2′-ethanesulfonic acid at a pH or in the range of 7.6 to 8.0 depending upon temperature. Five fish cell lines collectively capable of replicating all fish viruses thus far isolated were tested and quantitatively found to grow comparably well in the three media. Two-phase (gel-liquid) media incorporating the various buffer systems allowed plaquing at 15 to 33 C either in partial pressures of CO2 or in normal atmosphere, but greater efficiency and sensitivity were obtained with the organic buffers, and, overall, the best results were obtained with tris(hydroxymethyl)aminomethane. Epizootiological data, specific fish cell line response, and plaque morphology permit presumptive identification of most of the agents. At proper pH, use of organic buffers obviates the need for CO2 incubators. Images PMID:4349252

Phosphate-enhanced cytotoxicity of zinc oxide nanoparticles and agglomerates.

PubMed

Everett, W Neil; Chern, Christina; Sun, Dazhi; McMahon, Rebecca E; Zhang, Xi; Chen, Wei-Jung A; Hahn, Mariah S; Sue, H-J

2014-02-10

Zinc oxide (ZnO) nanoparticles (NPs) have been found to readily react with phosphate ions to form zinc phosphate (Zn3(PO4)2) crystallites. Because phosphates are ubiquitous in physiological fluids as well as waste water streams, it is important to examine the potential effects that the formation of Zn3(PO4)2 crystallites may have on cell viability. Thus, the cytotoxic response of NIH/3T3 fibroblast cells was assessed following 24h of exposure to ZnO NPs suspended in media with and without the standard phosphate salt supplement. Both particle dosage and size have been shown to impact the cytotoxic effects of ZnO NPs, so doses ranging from 5 to 50 μg/mL were examined and agglomerate size effects were investigated by using the bioinert amphiphilic polymer polyvinylpyrrolidone (PVP) to generate water-soluble ZnO ranging from individually dispersed 4 nm NPs up to micron-sized agglomerates. Cell metabolic activity measures indicated that the presence of phosphate in the suspension media can led to significantly reduced cell viability at all agglomerate sizes and at lower ZnO dosages. In addition, a reduction in cell viability was observed when agglomerate size was decreased, but only in the phosphate-containing media. These metabolic activity results were reflected in separate measures of cell death via the lactate dehydrogenase assay. Our results suggest that, while higher doses of water-soluble ZnO NPs are cytotoxic, the presence of phosphates in the surrounding fluid can lead to significantly elevated levels of cell death at lower ZnO NP doses. Moreover, the extent of this death can potentially be modulated or offset by tuning the agglomerate size. These findings underscore the importance of understanding how nanoscale materials can interact with the components of surrounding fluids so that potential adverse effects of such interactions can be controlled. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Tailoring of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) copolymers for bone tissue applications

NASA Astrophysics Data System (ADS)

Liu, Hui

Considerable scientific and technological progress has been made in formulating biomaterials based on natural and synthetic polymers for ultimate use in bone tissue scaffolding. One class of polymers that has drawn attention in recent years for bone tissue engineering application is the biodegradable polymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). PHBV, a microbial polymer, has gained special importance because of favorable mechanical characteristics, biological properties, highly adaptable structure, non-toxic degradation products, and minimal inflammatory response when used as scaffold. However, the lack of natural cell recognition sites on PHBV has resulted in delayed cell attachment, proliferation, differentiation, and tissue regeneration on the polymer. The primary objective of this research is to modify PHBV so as to improve the biocompatibility of the matrix. An approach was developed to prepare porous and bioactive molecule coated scaffold so as to improve the biocompatibility of PHBV matrix. We investigated the role of porosity, collagen coating, and ozone treatment of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) scaffold on cell proliferation. Based on biochemical assay, we established that maximum cell proliferation occurs on collagen coated and ozone treated porous PHBV film followed by collagen coated porous PHBV film than on porous PHBV film and the least on nonporous PHBV film. Confocal microscopy in combination with biochemical assay was used to generate 3D map of viable cell proliferation on the bulk PHBV matrix. The cells were cultivated on modified PHBV film in mineralization media containing beta-glycerol phosphate for predetermined time interval and later calcium deposits were stained with alizarin red-S assay. Atomic absorption (AA) technique was used to measure the Ca2+ content of the medium and it was found that the longer the cells were incubated in organic phosphate medium, the greater amount of Ca2+ from the medium is mineralized. The phenotypic character of the cells grown on modified PHBV matrix was compared against TCPS (a positive control). RNA was extracted from the UMR-106 cells, and reverse transcriptase-polymerase chain reaction (RT-PCR) was applied to detect expression of glyceraldehyde 3-phosphate dehydrogenase (GAPDH) (a house keeping gene) and bone sialoprotein (BSP) (marker of the osteoblastic phenotype) on both matrices. Cells grown on both modified porous and nonporous PHBV were found to retain their original phenotypic character. In addition to evaluating the biocompatibility of modified PHBV, an attempt was made to investigate the degradability of PHBV in physiological medium (phosphate buffer medium at 37°C). The degradation was followed by monitoring the time dependent changes in chemical composition and mass loss of the macroporous films. FT-1R data of the bulk film showed ester hydrolysis upon long immersion of PHBV film in buffer medium. The mass loss of PHBV film after 19 weeks of exposure to buffer medium was found to range from 2.8 % to 9.2 % with a strong dependence on the HV content of the original copolyester. Like mass loss data, the NMR results showed a big drop in the mol% of HV content for degraded copolymer with high HV content of the copolymer. Information generated from this study can be useful in the selection of appropriate PHBV copolymer for clinical applications where the biopolymer needs to remain intact during the period of short term use.

Electrochemical lactate biosensor based upon chitosan/carbon nanotubes modified screen-printed graphite electrodes for the determination of lactate in embryonic cell cultures.

PubMed

Hernández-Ibáñez, Naiara; García-Cruz, Leticia; Montiel, Vicente; Foster, Christopher W; Banks, Craig E; Iniesta, Jesús

2016-03-15

l-lactate is an essential metabolite present in embryonic cell culture. Changes of this important metabolite during the growth of human embryo reflect the quality and viability of the embryo. In this study, we report a sensitive, stable, and easily manufactured electrochemical biosensor for the detection of lactate within embryonic cell cultures media. Screen-printed disposable electrodes are used as electrochemical sensing platforms for the miniaturization of the lactate biosensor. Chitosan/multi walled carbon nanotubes composite have been employed for the enzymatic immobilization of the lactate oxidase enzyme. This novel electrochemical lactate biosensor analytical efficacy is explored towards the sensing of lactate in model (buffer) solutions and is found to exhibit a linear response towards lactate over the concentration range of 30.4 and 243.9 µM in phosphate buffer solution, with a corresponding limit of detection (based on 3-sigma) of 22.6 µM and exhibits a sensitivity of 3417 ± 131 µAM(-1) according to the reproducibility study. These novel electrochemical lactate biosensors exhibit a high reproducibility, with a relative standard deviation of less than 3.8% and an enzymatic response over 82% after 5 months stored at 4 °C. Furthermore, high performance liquid chromatography technique has been utilized to independently validate the electrochemical lactate biosensor for the determination of lactate in a commercial embryonic cell culture medium providing excellent agreement between the two analytical protocols. Copyright © 2015 Elsevier B.V. All rights reserved.

Vtc5, a Novel Subunit of the Vacuolar Transporter Chaperone Complex, Regulates Polyphosphate Synthesis and Phosphate Homeostasis in Yeast*

PubMed Central

Desfougères, Yann; Gerasimaitė, R̄uta; Jessen, Henning Jacob

2016-01-01

SPX domains control phosphate homeostasis in eukaryotes. Ten genes in yeast encode SPX-containing proteins, among which YDR089W is the only one of unknown function. Here, we show that YDR089W encodes a novel subunit of the vacuole transporter chaperone (VTC) complex that produces inorganic polyphosphate (polyP). The polyP synthesis transfers inorganic phosphate (Pi) from the cytosol into the acidocalcisome- and lysosome-related vacuoles of yeast, where it can be released again. It was therefore proposed for buffer changes in cytosolic Pi concentration (Thomas, M. R., and O'Shea, E. K. (2005) Proc. Natl. Acad. Sci. U.S.A. 102, 9565–9570). Vtc5 physically interacts with the VTC complex and accelerates the accumulation of polyP synthesized by it. Deletion of VTC5 reduces polyP accumulation in vivo and in vitro. Its overexpression hyperactivates polyP production and triggers the phosphate starvation response via the PHO pathway. Because this Vtc5-induced starvation response can be reverted by shutting down polyP synthesis genetically or pharmacologically, we propose that polyP synthesis rather than Vtc5 itself is a regulator of the PHO pathway. Our observations suggest that polyP synthesis not only serves to establish a buffer for transient drops in cytosolic Pi levels but that it can actively decrease or increase the steady state of cytosolic Pi. PMID:27587415

Live attenuated influenza virus increases pneumococcal translocation and persistence within the middle ear.

PubMed

Mina, Michael J; Klugman, Keith P; Rosch, Jason W; McCullers, Jonathan A

2015-07-15

Infection with influenza A virus (IAV) increases susceptibility to respiratory bacterial infections, resulting in increased bacterial carriage and complications such acute otitis media, pneumonia, bacteremia, and meningitis. Recently, vaccination with live attenuated influenza virus (LAIV) was reported to enhance subclinical bacterial colonization within the nasopharynx, similar to IAV. Although LAIV does not predispose to bacterial pneumonia, whether it may alter bacterial transmigration toward the middle ear, where it could have clinically relevant implications, has not been investigated. BALB/c mice received LAIV or phosphate-buffered saline 1 or 7 days before or during pneumococcal colonization with either of 2 clinical isolates, 19F or 7F. Middle ear bacterial titers were monitored daily via in vivo imaging. LAIV increased bacterial transmigration to and persistence within the middle ear. When colonization followed LAIV inoculation, a minimum LAIV incubation period of 4 days was required before bacterial transmigration commenced. While LAIV vaccination is safe and effective at reducing IAV and coinfection with influenza virus and bacteria, LAIV may increase bacterial transmigration to the middle ear and could thus increase the risk of clinically relevant acute otitis media. These data warrant further investigations into interactions between live attenuated viruses and naturally colonizing bacterial pathogens. © The Author 2014. Published by Oxford University Press on behalf of the Infectious Diseases Society of America. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

Phosphorus Amendment Efficacy for In Situ Remediation of Soil Lead Depends on the Bioaccessible Method.

PubMed

Obrycki, John F; Basta, Nicholas T; Scheckel, Kirk; Stevens, Brooke N; Minca, Kristen K

2016-01-01

A validated method is needed to measure reductions of in vitro bioaccessible (IVBA) Pb in urban soil remediated with amendments. This study evaluated the effect of in vitro extraction solution pH and glycine buffer on bioaccessible Pb in P-treated soils. Two Pb-contaminated soils (790-1300 mg Pb kg), one from a garden and one from a city lot in Cleveland, OH, were incubated in a bench scale experiment for 1 yr. Six phosphate amendments, including bone meal, fish bone, poultry litter, monoammonium phosphate, diammonium phosphate, and triple superphosphate, were added to containers at two application rates. Lead IVBA was assessed using USEPA Method 1340 and three modified versions of this method. Modifications included using solutions with pH 1.5 and 2.5 as well as using solutions with and without 0.4 mol L glycine. Soil amendments were ineffective in reducing IVBA Pb in these soils as measured by pH 1.5 with glycine buffer. The greatest reductions in IVBA Pb, from 5 to 26%, were found using pH 2.5 extractions. Lead mineral results showed several soil amendments promoted Pb phosphate formation, an indicator of remediation success. A significant negative linear relationship between reduction in IVBA Pb and Pb-phosphate formation was found only for pH 2.5 without glycine extraction solution. A modified USEPA Method 1340 without glycine and using pH 2.5 has the potential to predict P soil treatment efficacy and reductions in bioavailable Pb. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

On the Stability of DNA Origami Nanostructures in Low-Magnesium Buffers.

PubMed

Kielar, Charlotte; Xin, Yang; Shen, Boxuan; Kostiainen, Mauri A; Grundmeier, Guido; Linko, Veikko; Keller, Adrian

2018-05-25

DNA origami have great potential as functional platforms in various biomedical applications. Many applications, however, are incompatible with the high Mg2+ concentrations commonly believed to be a prerequisite for maintaining DNA origami integrity. Here, we investigate DNA origami stability in low-Mg2+ buffers. DNA origami stability is found to crucially depend on the availability of residual Mg2+ ions for screening electrostatic repulsion. The presence of EDTA and phosphate ions may thus facilitate DNA origami denaturation by displacing Mg2+ ions from the DNA backbone and reducing the strength of the Mg2+-DNA interaction, respectively. Most remarkably, these buffer dependencies are affected by DNA origami superstructure. However, by rationally selecting buffer components and considering superstructure-dependent effects, the structural integrity of a given DNA origami nanostructure can be maintained in conventional buffers even at Mg2+ concentrations in the low-μM range. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemical Modification of the Olfactory Receptor Epithelium of Vertebrate Species

DTIC Science & Technology

1990-06-28

Pre-column Derivatization Procedure: 1.0 mL of the Jeffamine solution was mixed with 1.0 mL of NaCN, 5.0 mL of phosphate buffer pH 9.5 followed by 1.0...running buffer. All the unprotonated components elute at the same time because their rate of elution is controlled only by the rate of electroosmotic ...elecarosomotic mobility under our experimental conditions. Using an average elution time of 22.2 min the measured electroosmotic mobility is 1.3 x 10-4 cm2

Initial-phase optimization for bioremediation of munition compound-contaminated soils.

PubMed Central

Funk, S B; Roberts, D J; Crawford, D L; Crawford, R L

1993-01-01

We examined the bioremediation of soils contaminated with the munition compounds 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine, and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetraazocine by a procedure that produced anaerobic conditions in the soils and promoted the biodegradation of nitroaromatic contaminants. This procedure consisted of flooding the soils with 50 mM phosphate buffer, adding starch as a supplemental carbon substrate, and incubating under static conditions. Aerobic heterotrophs, present naturally in the soil or added as an inoculum, quickly removed the oxygen from the static cultures, creating anaerobic conditions. Removal of parent TNT molecules from the soil cultures by the strictly anaerobic microflora occurred within 4 days. The reduced intermediates formed from TNT and hexahydro-1,3,5-trinitro-1,3,5-triazine were removed from the cultures within 24 days, completing the first stage of remediation. The procedure was effective over a range of incubation temperatures, 20 to 37 degrees C, and was improved when 25 mM ammonium was added to cultures buffered with 50 mM potassium phosphate. Ammonium phosphate buffer (50 mM), however, completely inhibited TNT reduction. The optimal pH for the first stage of remediation was between 6.5 and 7.0. When soils were incubated under aerobic conditions or under anaerobic conditions at alkaline pHs, the TNT biodegradation intermediates polymerized. Polymerization was not observed at neutral to slightly acidic pHs under anaerobic conditions. Completion of the first stage of remediation of munition compound-contaminated soils resulted in aqueous supernatants that contained no munition residues or aminoaromatic compounds. PMID:8357251

Knot Security of 5 Metric (USP 2) Sutures: Influence of Knotting Technique, Suture Material, and Incubation Time for 14 and 28 Days in Phosphate Buffered Saline and Inflamed Equine Peritoneal Fluid.

PubMed

Sanders, Ruth E; Kearney, Clodagh M; Buckley, Conor T; Jenner, Florien; Brama, Pieter A

2015-08-01

To evaluate knot security for 3 knot types created in 3 commonly used 5 metric suture materials incubated in physiological and pathological fluids. In vitro mechanical study. Knotted suture loops (n = 5/group). Loops of 3 different suture materials (glycolide/lactide copolymer; polyglactin 910; polydioxanone) were created around a 20 mm rod using 3 knot types (square [SQ], surgeon's [SK], and triple knot [TK]) and were tested to failure in distraction (6 mm/min) after tying (day 0) and after being incubated for 14 and 28 days in phosphate buffered saline (PBS) or inflamed peritoneal fluid. Failure load (N) and mode were recorded and compared. For polydioxanone, significant differences in force to knot failure were found between SQ and SK/TK but not between SK and TK. The force required to break all constructs increased after incubation in phosphate buffered saline (PBS). With glycolide/lactide copolymer no differences in force to knot failure were observed. With polyglactin 910, a significant difference between SQ and TK was observed, which was not seen between the other knot types. Incubation in inflamed peritoneal fluid caused a larger and more rapid decrease in force required to cause knot failure than incubation in PBS. Mechanical properties of suture materials have significant effects on knot security. For polydioxanone, SQ is insufficient to create a secure knot. Additional wraps above a SK confer extra stability in some materials, but this increase may not be clinically relevant or justifiable. Glycolide/lactide copolymer had excellent knot security. © Copyright 2015 by The American College of Veterinary Surgeons.

Mixed microalgae consortia growth under higher concentration of CO2 from unfiltered coal fired flue gas: Fatty acid profiling and biodiesel production.

PubMed

Aslam, Ambreen; Thomas-Hall, Skye R; Manzoor, Maleeha; Jabeen, Faiza; Iqbal, Munawar; Uz Zaman, Qamar; Schenk, Peer M; Asif Tahir, M

2018-02-01

Biodiesel is produced by transesterification of fatty acid methyl esters (FAME) from oleaginous microalgae feedstock. Biodiesel fuel properties were studied and compared with biodiesel standards. Qualitative analysis of FAME was done while cultivating mixed microalgae consortia under three concentrations of coal fired flue gas (1%, 3.0% and 5.5% CO 2 ). Under 1% CO 2 concentration (flue gas), the FAME content was 280.3 μg/mL, whereas the lipid content was 14.03 μg/mL/D (day). Both FAMEs and lipid contents were low at other CO 2 concentrations (3.0 and 5.5%). However, mixed consortia in the presence of phosphate buffer and flue gas (PB + FG) showed higher saturated fatty acids (SFA) (36.28%) and unsaturated fatty acids (UFA) (63.72%) versus 5.5% CO 2 concentration, which might be responsible for oxidative stability of biodiesel. Subsequently, higher cetane number (52) and low iodine value (136.3 gI 2 /100 g) biodiesel produced from mixed consortia (PB + FG) under 5.5% CO 2 along with 50 mM phosphate buffer were found in accordance with European (EN 14214) standard. Results revealed that phosphate buffer significantly enhanced the biodiesel quality, but reduced the FAME yield. This study intended to develop an integrated approach for significant improvement in biodiesel quality under surplus phosphorus by utilizing waste flue gas (as CO 2 source) using microalgae. The CO 2 sequestration from industrial flue gas not only reduced greenhouse gases, but may also ensure the sustainable and eco-benign production of biodiesel. Copyright © 2018. Published by Elsevier B.V.

Improvement of Starch Digestion Using α-Amylase Entrapped in Pectin-Polyvinyl Alcohol Blend

PubMed Central

Cruz, Maurício; Fernandes, Kátia; Cysneiros, Cristine; Nassar, Reginaldo; Caramori, Samantha

2015-01-01

Polyvinyl alcohol (PVA) and pectin blends were used to entrap α-amylase (Termamyl) using glutaraldehyde as a cross-linker. The effect of glutaraldehyde concentration (0.25, 0.5, 0.75, 1.0, and 1.25%) on the activity of the immobilized enzyme and rate of enzyme released was tested during a 24 h period. Characteristics of the material, such as scanning electron microscopy (SEM), tensile strength (TS), elongation, and rate of dissolution in water (pH 5.7), ruminal buffering solution (pH 7.0), and reactor containing 0.1 mol L−1 sodium phosphate buffer (pH 6.5), were also analyzed. SEM results showed that the surfaces of the pectin/PVA/amylase films were highly irregular and rough. TS values increased as a function of glutaraldehyde concentration, whereas percentage of elongation (%E) decreased. Pectin/PVA/amylase films presented similar values of solubility in the tested solvents. The material obtained with 0.25% glutaraldehyde performed best with repeated use (active for 24 h), in a phosphate buffer reactor. By contrast, the material obtained with 1.25% glutaraldehyde presented higher performance during in vitro testing using an artificial rumen. The results suggest that pectin/PVA/amylase is a highly promising material for biotechnological applications. PMID:25949991

Entrapment of ovalbumin into liposomes--factors affecting entrapment efficiency, liposome size, and zeta potential.

PubMed

Brgles, Marija; Jurasin, Darija; Sikirić, Maja Dutour; Frkanec, Ruza; Tomasić, Jelka

2008-01-01

Various amounts of Ovalbumin (OVA) were encapsulated into positively and negatively charged multilamellar liposomes, with the aim to investigate the entrapment efficiency in different buffers and to study their effects on the liposome size and zeta potential. Results showed that the entrapment efficiency of OVA in anionic liposomes was the same in 10 mM Phosphate Buffer (PB) as in Phosphate-Buffered Saline (PBS; PB + 0.15 M NaCl). Also, liposome size was approximately 1200 nm for all anionic liposomes incorporating OVA. The entrapment efficiency of OVA in cationic liposomes was highly dependent on ionic strength. The size of cationic liposomes was approximately 1200 nm in PBS, regardless of protein content, but increased with the amount of the incorporated protein in PB. Aggregation of cationic liposomes in PB was observed when the mass of the protein was 2.5 mg or greater. The zeta potential of anionic liposomes was negative and of cationic liposomes positive in the whole range of protein mass tested. These results show how different compositions of lipid and aqueous phases can be used to vary the entrapment efficiency, liposome size, and zeta potential--the factors that are of great importance for the use of liposomes as drug carriers.

The determination of calcium in phosphate, carbonate, and silicate rocks by flame photometer

USGS Publications Warehouse

Kramer, Henry

1956-01-01

A method has been developed for the determination of calcium in phosphate, carbonate, and silicate rocks using the Beckman flame photometer, with photomultiplier attachement. The sample is dissolved in hydrofluoric, nitric, and perchloric acids, the hydrofluoric and nitric acids are expelled, a radiation buffer consisting of aluminum, magnesium, iron, sodium, potassium, phosphoric acid, and nitric acid is added, and the solution is atomized in an oxy-hydrogen flame with an instrument setting of 554 mµ. Measurements are made by comparison against calcium standards, prepared in the same manner, in the 0 to 50 ppm range. The suppression of calcium emission by aluminum and phosphate was overcome by the addition of a large excess of magnesium. This addition almost completely restores the standard curve obtained from a solution of calcium nitrate. Interference was noted when the iron concentration in the aspirated solution (including the iron from the buffer) exceeded 100 ppm iron. Other common rock-forming elements did not interfere. The results obtained by this procedure are within ± 2 percent of the calcium oxide values obtained by other methods in the range 1 to 95 percent calcium oxide. In the 0 to 1 percent calcium oxide range the method compares favorably with standard methods.

Buffer capacity of biologics--from buffer salts to buffering by antibodies.

PubMed

Karow, Anne R; Bahrenburg, Sven; Garidel, Patrick

2013-01-01

Controlling pH is essential for a variety of biopharmaceutical process steps. The chemical stability of biologics such as monoclonal antibodies is pH-dependent and slightly acidic conditions are favorable for stability in a number of cases. Since control of pH is widely provided by added buffer salts, the current study summarizes the buffer characteristics of acetate, citrate, histidine, succinate, and phosphate buffers. Experimentally derived values largely coincide with values calculated from a model that had been proposed in 1922 by van Slyke. As high concentrated protein formulations become more and more prevalent for biologics, the self-buffering potential of proteins becomes of relevance. The current study provides information on buffer characteristics for pH ranges down to 4.0 and up to 8.0 and shows that a monoclonal antibody at 50 mg/mL exhibits similar buffer capacity as 6 mM citrate or 14 mM histidine (pH 5.0-6.0). Buffer capacity of antibody solutions scales linearly with protein concentration up to more than 200 mg/mL. At a protein concentration of 220 mg/mL, the buffer capacity resembles the buffer capacity of 30 mM citrate or 50 mM histidine (pH 5.0-6.0). The buffer capacity of monoclonal antibodies is practically identical at the process relevant temperatures 5, 25, and 40°C. Changes in ionic strength of ΔI=0.15, in contrast, can alter the buffer capacity up to 35%. In conclusion, due to efficient self-buffering by antibodies in the pH range of favored chemical stability, conventional buffer excipients could be dispensable for pH stabilization of high concentrated protein solutions. Copyright © 2013 American Institute of Chemical Engineers.

Impact of Red Water System (RWS) application on water quality of catfish culture using aquaponics

NASA Astrophysics Data System (ADS)

Zahidah; Dhahiyat, Y.; Andriani, Y.; Sahidin, A.; Farizi, I.

2018-03-01

This study aim was to analyze the effect of Red Water System (RWS) probiotics application on water quality in aquaponic system. The research used experimental method using Completely Randomized Design (CRD) with five treatments and three replications. Treatment A: RWS 7.5 μL·L-1/week without aquaponic probiotic, Treatment B: aquaponic without RWS probiotics, treatment C: RWS probiotic addition in aquaponic media at 7.5 μL·L-1/week, treatment D: addition of RWS probiotics in aquaponic media at 10 μL·L-1/week and treatment E: addition of RWS probiotics in in aquaponic media at 12.8 μL·L-1/week. Parameters measured were pH, temperature, ammonia, nitrate and phosphate. The results showed that water temperature and pH relatively unchanged in all treatments. The addition of RWS probiotics did not improve the concentration of ammonia, nitrate and phosphate. In fact, the catfish culture with only aquaponic resulted lower concentration of ammonia, nitrate and phosphate than other treatment. The lowest value of ammonia, nitrate and phosphates was obtained in the experimental groups of aquaponic with RWS of 10 μL·L-1/week (Treatment D). Treatment D has the lowest average ammonia of 0.50 ppm, reduced nitrate up to 60.78 % and temperature and pH relatively unchanged.

Amperometric Determination of Glucose at Parts per Million Levels with Immobilized Glucose Oxidase.

ERIC Educational Resources Information Center

Sittampalam, G.; Wilson, G. S.

1982-01-01

An experiment on the operation and utility of an amperometric immobilized enzyme electrode (or probe) is described, including advantages of the experiment, equipment, reagents, preparation of phosphate buffer, enzyme immobilization techniques, laboratory procedures, precautions, and discussion of experimental results. (SK)

Distribution of spotted fever group rickettsiae in select tissues of experimentally infected and field-collected Gulf Coast ticks.

PubMed

Edwards, Kristine T; Goddard, Jerome; Varela-Stokes, Andrea

2011-05-01

Salivary glands, midgut, Malpighian tubules, and ovaries were dissected from infected, colony-derived Amblyomma maculatum (Gulf Coast ticks) injected as nymphs with either Rickettsia parkeri (a spotted fever group rickettsia [SFGR]; treatment) or phosphate-buffered saline (negative control). For comparison, similar tissues were dissected from hemolymph-positive, field-collected ticks. Tissues were analyzed by indirect fluorescent antibody (IFA) tests. All phosphate-buffered saline-injected ticks were IFA negative, whereas SFGR were detected by IFA in 100% of the salivary glands and ovaries and 78 and 75% of midgut and Malpighian tubule samples, respectively, of R. parkeri-injected ticks. Nearly 22% (10/46) of the field-collected ticks were hemolymph positive. Of those, SFGR were detected by IFA in 80% of the salivary glands, 67% of the ovaries, and 60% in the midgut and Malpighian tubules. This is the first study to assess the distribution of SFGR in select tissues of A. maculatum ticks.

Chitosan adsorption on nanofibrillated cellulose with different aldehyde content and interaction with phosphate buffered saline.

PubMed

Ondaral, Sedat; Çelik, Elif; Kurtuluş, Orçun Çağlar; Aşıkuzun, Elif; Yakın, İsmail

2018-04-15

The chitosan adsorption on films prepared using nanofibrillated cellulose (NFC) with different content of aldehyde group was studied by means of Quartz Crystal Microbalance with Dissipation (QCM-D). Results showed that frequency change (Δf) was higher when the chitosan adsorbed on NFC film consisting more aldehyde group indicating the higher adsorption. The (Δf) and dissipation (ΔD) factors completely changed during adsorption of chitosan pre-treated with acetic acid: Δf increased and ΔD decreased, oppositely to un-treated chitosan adsorption. After acid treatment, molecular weight and crystallinity index of chitosan decreased addition to change in chemical structure. It was found that more phosphate buffered saline (PBS), as a model liquid for wound exudate, adsorbed to acid treated chitosan-NFC film, especially to film having more aldehyde groups. Comparing with bare NFC film, chitosan-NFC films adsorbed less PBS because chitosan crosslinked the NFC network and blocked the functional groups of NFC and thus, preventing swelling film. Copyright © 2017 Elsevier Ltd. All rights reserved.

Development of a nucleotide sugar purification method using a mixed mode column & mass spectrometry detection.

PubMed

Eastwood, Heather; Xia, Fang; Lo, Mei-Chu; Zhou, Jing; Jordan, John B; McCarter, John; Barnhart, Wesley W; Gahm, Kyung-Hyun

2015-11-10

Analysis of nucleotide sugars, nucleoside di- and triphosphates and sugar-phosphates is an essential step in the process of understanding enzymatic pathways. A facile and rapid separation method was developed to analyze these compounds present in an enzymatic reaction mixture utilized to produce nucleotide sugars. The Primesep SB column explored in this study utilizes hydrophobic interactions as well as electrostatic interactions with the phosphoric portion of the nucleotide sugars. Ammonium formate buffer was selected due to its compatibility with mass spectrometry. Negative ion mode mass spectrometry was adopted for detection of the sugar phosphate (fucose-1-phophate), as the compound is not amenable to UV detection. Various mobile phase conditions such as pH, buffer concentration and organic modifier were explored. The semi-preparative separation method was developed to prepare 30mg of the nucleotide sugar. (19)F NMR was utilized to determine purity of the purified fluorinated nucleotide sugar. The collected nucleotide sugar was found to be 99% pure. Published by Elsevier B.V.

A Janus cobalt-based catalytic material for electro-splitting of water

NASA Astrophysics Data System (ADS)

Cobo, Saioa; Heidkamp, Jonathan; Jacques, Pierre-André; Fize, Jennifer; Fourmond, Vincent; Guetaz, Laure; Jousselme, Bruno; Ivanova, Valentina; Dau, Holger; Palacin, Serge; Fontecave, Marc; Artero, Vincent

2012-09-01

The future of energy supply depends on innovative breakthroughs regarding the design of cheap, sustainable and efficient systems for the conversion and storage of renewable energy sources. The production of hydrogen through water splitting seems a promising and appealing solution. We found that a robust nanoparticulate electrocatalytic material, H2-CoCat, can be electrochemically prepared from cobalt salts in a phosphate buffer. This material consists of metallic cobalt coated with a cobalt-oxo/hydroxo-phosphate layer in contact with the electrolyte and mediates H2 evolution from neutral aqueous buffer at modest overpotentials. Remarkably, it can be converted on anodic equilibration into the previously described amorphous cobalt oxide film (O2-CoCat or CoPi) catalysing O2 evolution. The switch between the two catalytic forms is fully reversible and corresponds to a local interconversion between two morphologies and compositions at the surface of the electrode. After deposition, the noble-metal-free coating thus functions as a robust, bifunctional and switchable catalyst.

Direct enantioseparation of catechin and epicatechin in tea drinks by 6-O-alpha-D-glucosyl-beta-cyclodextrin-modified micellar electrokinetic chromatography.

PubMed

Kodama, Shuji; Yamamoto, Atsushi; Matsunaga, Akinobu; Yanai, Hiroko

2004-08-01

Cyclodextrin-modified micellar electrokinetic chromatography was applied to the enantioseparation of catechin and epicatechin using 6-O-alpha-D-glucosyl-beta-cyclodextrin together with sodium dodecyl sulfate and borate-phosphate buffer. Factors affecting chiral resolution and migration time of catechin and epicatechin were studied. The optimum running conditions were found to be 200 mM borate-20 mM phosphate buffer (pH 6.4) containing 25 mM 6-O-alpha-D-glucosyl-beta-cyclodextrin and 240 mM sodium dodecyl sulfate with an effective voltage of +25 kV at 20 degrees C using direct detection at 210 nm. Under these conditions, the resolution (Rs) of racemic catechin and epicatechin were 4.15 and 1.92, respectively. With this system, catechin and epicatechin enantiomers along with other four catechins ((-)-catechin gallate, (-)-epicatechin gallate, (-)-epigallocatechin, (-)-epigallocatechin gallate) and caffeine in tea samples were analyzed successfully. The difference of migration time between catechin and epicatechin is discussed.

The use of antimicrobial peptides in ophthalmology: an experimental study in corneal preservation and the management of bacterial keratitis.

PubMed Central

Mannis, Mark J

2002-01-01

PURPOSE: Bacterial keratitis is an ocular infection with the potential to cause significant visual impairment. Increasing patterns of antibiotic resistance have necessitated the development of new antimicrobial agents for use in bacterial keratitis and other serious ocular infections. With a view to exploring the use of novel antimicrobial peptides in the management of ocular infection, we performed a series of experiments using synthetic antimicrobial peptides designed for the eradication of common and serious ophthalmic pathogens. METHODS: Experiments were performed with three clinical ocular isolates--Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis--in three experimental settings: (1) in vitro in a controlled system of 10 mM sodium phosphate buffer, (2) in vitro in modified chondroitin sulfate-based corneal preservation media (Optisol), and (3) in an in vivo animal model (rabbit) simulating bacterial keratitis. In all cases, outcomes were measured by quantitative microbiological techniques. RESULTS: The candidate peptides (CCI A, B, and C and COL-1) produced a total reduction of the test pathogens in phosphate buffered saline. In modified Optisol, the peptides were effective against S epidermidis at all temperatures, demonstrated augmented activity at 23 degrees C against the gram-positive organisms, but were ineffective against P aeruginosa. The addition of EDTA to the medium augmented the killing of P aeruginosa but made no difference in the reduction of gram-positive organisms. In an in vivo rabbit model of Pseudomonas keratitis, COL-1 demonstrated neither clinical nor microbicidal efficacy and appeared to have a very narrow dosage range, outside of which it appeared to be toxic to the ocular surface. CONCLUSION: Our data indicate that the antimicrobial peptides we tested were effective in vitro but not in vivo. In an age of increasing antibiotic resistance, antimicrobial peptides, developed over millions of years as innate defense mechanisms by plants and animals, may have significant potential for development as topical agents for the management of severe bacterial keratitis. However, modifications of the peptides, the drug delivery systems, or both, will be necessary for effective clinical application. PMID:12545697

A heparin-functionalized carbon nanotube-based affinity biosensor for dengue virus.

PubMed

Wasik, Daniel; Mulchandani, Ashok; Yates, Marylynn V

2017-05-15

Dengue virus is an arthropod-borne virus transmitted primarily by Aedes mosquitos and is major cause of disease in tropical and subtropical regions. Colloquially known as Dengue Fever, infection can cause hemorrhagic disorders and death in humans and non-human primates. We report a novel electronic biosensor based on a single-walled carbon nanotube network chemiresistive transducer that is functionalized with heparin for low-cost, label-free, ultra-sensitive, and rapid detection of whole dengue virus (DENV). Heparin, an analog of the heparan sulfate proteoglycans that are receptors for dengue virus during infection of Vero cells and hepatocytes, was used for the first time in a biosensor as a biorecognition element instead of traditional antibody. Detection of DENV in viral culture supernatant has similar sensitivity as the corresponding viral titer in phosphate buffer despite the presence of growth media and Vero cell lysate. The biosensor demonstrated sensitivity within the clinically relevant range for humans and infected Aedes aegypti. It has potential application in clinical diagnosis and can improve point-of-care diagnostics of dengue infection. Copyright © 2017 Elsevier B.V. All rights reserved.

Photodegradation of Dicloran in Freshwater and Seawater.

PubMed

Vebrosky, Emily N; Saranjampour, Parichehr; Crosby, Donald G; Armbrust, Kevin L

2018-03-21

Dicloran appears to be a model pesticide for investigating photodegradation processes in surface waters. Photodegradation processes are particularly relevant to this compound as it is applied to crops grown in proximity to freshwater and marine ecosystems. The photodegradation of dicloran under simulated sunlight was measured in distilled water, artificial seawater, phosphate buffer, and filter-sterilized estuarine water to determine its half-life, degradation rate, and photodegradation products. The half-life was approximately 7.5 h in all media. There was no significant difference in the rate of degradation between distilled water and artificial seawater for dicloran. For the intermediate products, a higher concentration of 2-chloro-1,4-benzoquinone was measured in artificial seawater versus distilled water, while a slightly higher concentration of 1,4-benzoquinone was measured in distilled water versus artificial seawater. The detection of chloride and nitrate ions after 2 h of light exposure suggests photonucleophilic substitution contributes to the degradation process. Differences in product distributions between water types suggest that salinity impacts on chemical degradation may need to be addressed in chemical exposure assessments.

Infectivity of Theileria parva sporozoites following cryopreservation in four suspension media and multiple refreezing: evaluation by in vitro titration.

PubMed

Mbao, V; Berkvens, D; Dolan, T; Speybroeck, N; Brandt, J; Dorny, P; Van den Bossche, P; Marcotty, T

2006-09-01

Theileria parva sporozoite stabilates are used for immunizing cattle against East Coast fever and in in vitro sporozoite neutralization assays. In this study, we attempted to identify a cheaper freezing medium and quantified the infectivity loss of sporozoites due to refreezing of stabilates, using an in vitro technique. Pools of stabilates prepared using Minimum Essential Medium (MEM), Roswell Park Memorial Institute (RPMI 1640), foetal calf serum (FCS) and phosphate-buffered saline (PBS) were compared. All were supplemented with bovine serum albumin except the FCS. RPMI 1640 was as effective as MEM in maintaining sporozoite infectivity while the infectivity in PBS and FCS reached only 59% and 67%, respectively. In a second experiment, a stabiiate based on MEM was subjected to several freeze-thaw cycles including various holding times on ice between thawing and refreezing. Refrozen stabilate gave an average sporozoite infectivity loss of 35% per cycle. The results indicate that RPMI can be used as a cheaper freezing medium for T. parva stabilates and that refrozen stabilate doses need to be adjusted for the 35% loss of infectivity.

MAPLE deposition of PLGA:PEG films for controlled drug delivery: Influence of PEG molecular weight

NASA Astrophysics Data System (ADS)

Paun, Irina Alexandra; Moldovan, Antoniu; Luculescu, Catalin Romeo; Staicu, Angela; Dinescu, Maria

2012-09-01

Implantable devices consisting of indomethacin (INC) cores coated with poly(lactide-co-glycolide):polyethylene glycol films (i.e. PLGA:PEG films) deposited by Matrix Assisted Pulsed Laser Evaporation (MAPLE) were produced. To predict their behavior after implantation inside the body, the implants were studied in vitro, in media similar with those encountered inside the body (phosphate buffered saline (PBS) pH 7.4 and blood). The influence of the molecular weight of PEG (i.e. low (1450 Da) versus high (10 kDa) molecular weights) on the characteristics of the implants was investigated, in terms of morphology, blood compatibility and kinetics of the drug release. The use of PEG of high molecular weight resulted in larger pores on the implants surfaces, enhanced blood compatibility of the implants and higher drug delivery rates. For both molecular weights PEGs, sustained release of INC was maintained over a three weeks interval. Theoretical fitting of the drug release data with Higuchi's model indicated that the INC was released mainly by diffusion, most probably through the pores formed in PLGA:PEG films during PBS immersion.

Synthesis and Characterization of Ca, Mg, La- PMMA Polymer Composites for Phosphate Removal

EPA Science Inventory

In this study calcium, magnesium and lanthanum- PMMA polymer composites were synthesized, characterized and investigated for phosphate removal from wastewater using rapid small scale column tests. Theoretical and experimental capacity of the media was determined and unused and sp...

Phosphate Removal using Modified Bayoxide®E33 Adsorption Media

EPA Science Inventory

The adsorption of phosphate onto modified Bayoxide® E33 (E33) and underlying mechanisms were comparatively investigated by batch kinetics, sorption isotherms, rapid small scale column tests, and material characterization. Synthesis of modified E33 was conducted by the addition of...

Metal sites in 3,4-dihydroxy-2-butanone 4-phosphate synthase from Methanococcus jannaschii in complex with the substrate ribulose 5-phosphate.

PubMed

Steinbacher, Stefan; Schiffmann, Susanne; Bacher, Adelbert; Fischer, Markus

2004-07-01

The crystal structure of Methanococcus jannaschii 3,4-dihydroxy-2-butanone 4-phosphate synthase in complex with the substrate ribulose 5-phosphate at a dimetal centre has recently been determined at 1.7 A resolution. The enzyme converts ribulose 5-phosphate into 3,4-dihydroxy-2-butanone 4-phosphate, while its C4 atom is released as formate. The resulting four-carbon body supplies all eight C atoms for the xylene moiety of riboflavin. Three of the four hydroxyl groups of ribulose 5-phosphate were coordinated by the metal ions. Based on crystallographic refinement, the metals were assigned as zinc and calcium, which were present in the crystallization buffer. Neither metal supports the enzymatic reaction. In the present study, the correctness of this assignment is assessed using anomalous diffraction data collected at the high-energy side of the zinc absorption edge (lambda = 1.2823 A). Only the three tentative zinc ions give strong peaks in an anomalous difference Fourier map (>20sigma), whereas the four tentative calcium ions do not show anomalous signals above the noise level. These results confirm the initial assignment. In addition, the resolution was improved to 1.55 A.

Countercurrent distribution of biological cells

NASA Technical Reports Server (NTRS)

1982-01-01

It is known that the addition of phosphate buffer to two polymer aqueous phase systems has a strong effect on the partition behavior of cells and other particles in such mixtures. The addition of sodium phosphate to aqueous poly(ethylene glycol) dextran phase systems causes a concentration-dependent shift in binodial on the phase diagram, progressively lowering the critical conditions for phase separation as the phosphate concentration is increased. Sodium chloride produces no significant shift in the critical point relative to the salt-free case. Accurate determinations of the phase diagram require measurements of the density of the phases; data is presented which allows this parameter to be calculated from polarimetric measurements of the dextran concentrations of both phases. Increasing polymer concentrations in the phase systems produce increasing preference of the phosphate for the dextran-rich bottom phase. Equilibrium dialysis experiments showed that poly(ethylene glycol) effectively rejected phosphate, and to a lesser extent chloride, but that dextran had little effect on the distribution of either salt. Increasing ionic strength via addition of 0.15 M NaCl to phase systems containing 0.01 M phosphate produces an increased concentration of phosphate ions in the bottom dextran-rich phase, the expected effect in this type of Donnan distribution.

Comparative study on in vitro biocompatibility of synthetic octacalcium phosphate and calcium phosphate ceramics used clinically.

PubMed

Morimoto, Shinji; Anada, Takahisa; Honda, Yoshitomo; Suzuki, Osamu

2012-08-01

The present study was designed to investigate the extent to which calcium phosphate bone substitute materials, including osteoconductive octacalcium phosphate (OCP), display cytotoxic and inflammatory responses based on their dissolution in vitro. Hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) ceramics, which are clinically used, as well as dicalcium phosphate dihydrate (DCPD) and synthesized OCP were compared. The materials were well characterized by chemical analysis, x-ray diffraction and Fourier transform infrared spectroscopy. Calcium and phosphate ion concentrations and the pH of culture media after immersion of the materials were determined. The colony forming rate of Chinese hamster lung fibroblasts was estimated with extraction of the materials. Proliferation of bone marrow stromal ST-2 cells and inflammatory cytokine TNF-α production by THP-1 cells grown on the material-coated plates were examined. The materials had characteristics that corresponded to those reported. DCPD was shown to dissolve the most in the culture media, with a marked increase in phosphate ion concentration and a reduction in pH. ST-2 cells proliferated well on the materials, with the exception of DCPD, which markedly inhibited cellular growth. The colony forming capacity was the lowest on DCPD, while that of the other calcium phosphates was not altered. In contrast, TNF-α was not detected even in cells grown on DCPD, suggesting that calcium phosphate materials are essentially non-inflammatory, while the solubility of the materials can affect osteoblastic and fibroblastic cellular attachment. These results indicate that OCP is biocompatible, which is similar to the materials used clinically, such as HA. Therefore, OCP could be clinically used as a biocompatible bone substitute material.

Spontaneous interfacial reaction between metallic copper and PBS to form cupric phosphate nanoflower and its enzyme hybrid with enhanced activity.

PubMed

He, Guangli; Hu, Weihua; Li, Chang Ming

2015-11-01

We herein report the spontaneous interfacial reaction between copper foil with 0.01 M phosphate buffered saline (PBS) to form free-standing cupric phosphate (Cu3(PO4)2) nanoflowers at ambient temperature. The underlying chemistry was thoroughly investigated and it is found that the formation of nanoflower is synergistically caused by dissolved oxygen, chlorine ions and phosphate ions. Enzyme-Cu3(PO4)2 hybrid nanoflower was further prepared successfully by using an enzyme-dissolving PBS solution and the enzymes in the hybrid exhibit enhanced biological activity. This work provides a facile route for large-scale synthesis of hierarchical inorganic and functional protein-inorganic hybrid architectures via a simple one-step solution-immersion reaction without using either template or surfactant, thus offering great potential for biosensing application among others. Copyright © 2015 Elsevier B.V. All rights reserved.

Statistical investigation of simulated fed intestinal media composition on the equilibrium solubility of oral drugs.

PubMed

Zhou, Zhou; Dunn, Claire; Khadra, Ibrahim; Wilson, Clive G; Halbert, Gavin W

2017-03-01

Gastrointestinal fluid is a complex milieu and it is recognised that gut drug solubility is different to that observed in simple aqueous buffers. Simulated gastrointestinal media have been developed covering fasted and fed states to facilitate in vitro prediction of gut solubility and product dissolution. However, the combination of bile salts, phospholipids, fatty acids and proteins in an aqueous buffered system creates multiple phases and drug solubility is therefore a complex interaction between these components, which may create unique environments for each API. The impact on solubility can be assessed through a statistical design of experiment (DoE) approach, to determine the influence and relationships between factors. In this paper DoE has been applied to fed simulated gastrointestinal media consisting of eight components (pH, bile salt, lecithin, sodium oleate, monoglyceride, buffer, salt and pancreatin) using a two level D-optimal design with forty-four duplicate measurements and four centre points. The equilibrium solubility of a range of poorly soluble acidic (indomethacin, ibuprofen, phenytoin, valsartan, zafirlukast), basic (aprepitant, carvedilol, tadalafil, bromocriptine) and neutral (fenofibrate, felodipine, probucol, itraconazole) drugs was investigated. Results indicate that the DoE provides equilibrium solubility values that are comparable to literature results for other simulated fed gastrointestinal media systems or human intestinal fluid samples. For acidic drugs the influence of pH predominates but other significant factors related to oleate and bile salt or interactions between them are present. For basic drugs pH, oleate and bile salt have equal significance along with interactions between pH and oleate and lecithin and oleate. Neutral drugs show diverse effects of the media components particularly with regard to oleate, bile salt, pH and lecithin but the presence of monoglyceride, pancreatin and buffer have significant but smaller effects on solubility. There are fourteen significant interactions between factors mainly related to the surfactant components and pH, indicating that the solubility of neutral drugs in fed simulated media is complex. The results also indicate that the equilibrium solubility of each drug can exhibit individualistic behaviour associated with the drug's chemical structure, physicochemical properties and interaction with media components. The utility of DoE for fed simulated media has been demonstrated providing equilibrium solubility values comparable with similar in vitro systems whilst also providing greater information on the influence of media factors and their interactions. The determination of a drug's gastrointestinal solubility envelope provides useful limits that can potentially be applied to in silico modelling and in vivo experiments. Copyright © 2017 The Authors. Published by Elsevier B.V. All rights reserved.

Biological Degradation of Tetrachloroethylene in Methanogenic Conditions

DTIC Science & Technology

1994-06-01

stock of neat PCE was not purged with N2-C0 2. Alcohol oxidase (from Pichia pasrori, phosphate-buffered 60 percent sucrose solution), peroxidase (Type...dechlorination of tetrachlorocthene in anaerobic aquifer microcosms by addition of short-chain organic acids or alcohols ," Appl. Environ. Microbiol. (58

The role of hydroxo-bridged dinuclear species and the influence of "innocent" buffers in the reactivity of cis-[Co(III)(cyclen)(H₂O)₂]³⁺ and [Co(III)(tren)(H₂O)₂]³⁺ complexes with biologically relevant ligands at physiological pH.

PubMed

Basallote, Manuel G; Martínez, Manuel; Vázquez, Marta

2014-07-28

In view of the relevance of the reactivity of inert tetraamine Co(III) complexes having two substitutionally active cis positions capable of interact with biologically relevant ligands, the study of the reaction of cis-[Co(cyclen)(H2O)2](3+) and [Co(tren)(H2O)2](3+) with chlorides, inorganic phosphate and 5'-CMP (5'-cytidinemonophosphate) has been pursued at physiological pH. The results indicate that, in addition to the actuation of the expected labilising conjugate-base mechanism, the formation of mono and inert bis hydroxo-bridged species is relevant for understanding their speciation and reactivity. The reactivity pattern observed also indicates the key role played by the "innocent" buffers frequently used in most in vitro studies, which can make the results unreliable in many cases. The differences between the reactivity of inorganic and biologically relevant phosphates has also been found to be remarkable, with outer-sphere hydrogen bonding interactions being a dominant factor for the process. While for the inorganic phosphate substitution process the formation of μ-η(2)-OPO2O represents the termination of the reactivity monitored, for 5'-CMP only the formation of η(1)-OPO3 species is observed, which evolve with time to the final dead-end bis hydroxo-bridged complexes. The promoted hydrolysis of the 5'-CMP phosphate has not been observed in any of the processes studied.

Kidney cell electrophoresis, continuing task

NASA Technical Reports Server (NTRS)

Todd, P. W.

1985-01-01

Materials and procedures for microgravity electrophoresis of living human embryonic kidney cells were evaluated to provide ground support in the form of analytical cell electrophoresis and flow cytometry. Preflight culture media, electrophoresis buffer, fraction collection media, temperature profiles, and urokinase assay procedures were tested prior to flight. Electrophoretic mobility distributions of aliquots of the cell population to be fractionated in flight were obtained. Cells were prepared in suspension prior to flight in electrophoresis buffer and 10% calf serum. Electrophoretic separation proceeded in electrophoresis buffer without serum in the Continuous Flow Electrophoretic Separator, and fractions were collected into sample bags containing culture medium and concentrated serum. Fractions that yielded enough progeny cells were analyzed for morphology and electrophoretic mobility distributions. It is noted that the lowest mobility fraction studied produced higher mobility progeny while the other fractions produced progeny cells with mobilities related to the fractions from which they were collected.

The effect of pH, buffer capacity and ionic strength on quetiapine fumarate release from matrix tablets prepared using two different polymeric blends.

PubMed

Hamed, Rania; AlJanabi, Reem; Sunoqrot, Suhair; Abbas, Aiman

2017-08-01

The objective of this study was to investigate the effect of the different physiological parameters of the gastrointestinal (GI) fluid (pH, buffer capacity, and ionic strength) on the in vitro release of the weakly basic BCS class II drug quetiapine fumarate (QF) from two once-a-day matrix tablet formulations (F1 and F2) developed as potential generic equivalents to Seroquel ® XR. F1 tablets were prepared using blends of high and low viscosity grades of hydroxypropyl methylcellulose (HPMC K4M and K100LV, respectively), while F2 tablets were prepared from HPMC K4M and PEGylated glyceryl behenate (Compritol ® HD5 ATO). The two formulations attained release profiles of QF over 24 h similar to that of Seroquel ® XR using the dissolution medium published by the Food and Drug Administration (FDA). A series of solubility and in vitro dissolution studies was then carried out using media that simulate the gastric and intestinal fluids and cover the physiological pH, buffer capacity and ionic strength range of the GIT. Solubility studies revealed that QF exhibits a typical weak base pH-dependent solubility profile and that the solubility of QF increases with increasing the buffer capacity and ionic strength of the media. The release profiles of QF from F1, F2 and Seroquel ® XR tablets were found to be influenced by the pH, buffer capacity and ionic strength of the dissolution media to varying degrees. Results highlight the importance of studying the physiological variables along the GIT in designing controlled release formulations for more predictive in vitro-in vivo correlations.

Elasticity and breaking strength of synthetic suture materials incubated in various equine physiological and pathological solutions.

PubMed

Kearney, C M; Buckley, C T; Jenner, F; Moissonnier, P; Brama, P A J

2014-07-01

Selection of suture material in equine surgery is often based on costs or subjective factors, such as the surgeon's personal experience, rather than objective facts. The amount of objective data available on durability of suture materials with regard to specific equine physiological conditions is limited. To evaluate the effect of various equine physiological and pathological fluids on the rate of degradation of a number of commonly used suture materials. In vitro material testing. Suture materials were exposed in vitro to physiological fluid, followed by biomechanical analysis. Three absorbable suture materials, glycolide/lactide copolymer, polyglactin 910 and polydioxanone were incubated at 37°C for 7, 14 or 28 days in phosphate-buffered saline, equine serum, equine urine and equine peritoneal fluid from an animal with peritonitis. Five strands of each suture material type were tested to failure in a materials testing machine for each time point and each incubation medium. Yield strength, strain and Young's modulus were calculated, analysed and reported. For all suture types, the incubation time had a significant effect on yield strength, percentage elongation and Young's modulus in all culture media (P<0.0001). Suture type was also shown significantly to influence changes in each of yield strength, percentage elongation and Young's modulus in all culture media (P<0.0001). While the glycolide/lactide copolymer demonstrated the highest Day 0 yield strength, it showed the most rapid degradation in all culture media. For each of the 3 material characteristics tested, polydioxanone showed the least variation across the incubation period in each culture medium. The duration of incubation and the type of fluid have significant effects on the biomechanical properties of various suture materials. These findings are important for evidence-based selection of suture material in clinical cases. © 2013 EVJ Ltd.

Contact lens care solutions downregulate membrane-associated mucins 1 and 16 in cultured human corneal epithelial cells and at the rat corneal surface in vivo.

PubMed

Tchedre, Kissaou; Imayasu, Masaki; Hori, Yuichi; Cavanagh, H Dwight

2013-11-01

The purpose of this study was first to evaluate the effect of multipurpose contact lens care solutions (MPSs) on the expression of membrane-associated mucins (MUC1 and MUC16) in SV40-transformed human corneal epithelial (HCE-T) cells and in vivo rat cornea. The second aim of this study was to determine the role of the common MPS additive boric acid in reducing mucin expression and release. The HCE-T cells were exposed to different concentrations of MPS-F, MPS-G, MPS-H, MPS-I, and MPS-J with 100% treatment for 30 minutes and 10% treatment for 24 hours. MUC1 and MUC16 expressions were subsequently analyzed by Western blotting. Wister rats were also subjected to MPS-A, MPS-B, MPS-C, MPS-D, and MPS-E and received phosphate-buffered saline exposure (1 drop in the right eye every 10 minutes for 1 hour). The left eye was used as control. Cornea sections and lysates were used for the immunohistochemical assay of MUC1 and MUC16 expressions. Conditioned media from treated HCE-T cells were also analyzed using Western blotting. The MPSs containing boric acid downregulated MUC1 and MUC16 in the rat cornea, whereas MPSs without boric acid had no effect as demonstrated by the Western blotting and immunohistochemical analysis. Conditioned media from MPS-containing boric acid revealed some trace of MUC16. The clinical use of MPSs containing boric acid that reduce MUC1 and MUC16 availability should be avoided. Additionally, the presence of MUC16 in the conditioned media suggests that boric acid may have enhanced cleavage of MUC16 at the cell membrane surface.

Remote-loading labeling of liposomes with (99m)Tc-BMEDA and its stability evaluation: effects of lipid formulation and pH/chemical gradient.

PubMed

Li, Shihong; Goins, Beth; Phillips, William T; Bao, Ande

2011-03-01

Efficient, convenient, and stable radiolabeling plays a critical role for the monitoring of liposome behavior via either blood sampling, organ distribution, or noninvasive nuclear imaging. The direct labeling of liposome-carrying drugs without any prior modification undoubtedly is convenient and optimal for liposomal drug testing. In this article, we investigated the effect of various lipid formulations and pH/chemical gradients on the radiolabeling efficiency and entrapment stability of technetium-99m ((99m)Tc) remotely loaded into liposomes, using (99m)Tc-N,N-bis(2-mercaptoethyl)-N',N'-diethyl-ethylenediamine ((99m)Tc-BMEDA) complex. The tested liposomes either contained unsaturated lipid or possessed various surface charges. (99m)Tc could be efficiently loaded into various premanufactured liposomes containing either an ammonium sulfate pH, citrate pH, or glutathione (GSH) chemical gradient. (99m)Tc-entrapment stabilities of these liposomes in phosphate-buffered saline (PBS; pH 7.4) buffer at 25°C were mainly dependent on the pH/chemical gradient, but not lipid formulation. Stability sequence was ammonium sulfate pH-gradient>citrate pH-gradient>GSH-gradient. Stabilities of (99m)Tc-liposomes in 50% fetal bovine serum (FBS)/PBS (pH 7.4) buffer at 37°C are dependent on both lipid formulation and pH/chemical gradient. Specifically, (99m)Tc labeling of the ammonium sulfate pH-gradient liposomes were less stable in 50% FBS/PBS than in PBS, whereas noncationic liposomes with citrate pH- or GSH-gradient displayed higher stability, except that anionic citrate pH-gradient liposomes showed no stability difference in these two media. Cationic liposomes aggregated in 50% FBS/PBS, forming a new discrete fraction with larger particle sizes. These in vitro characterization results have indicated the optimism of using (99m)Tc-BMEDA for labeling pH/GSH gradient liposomes without the requirement of modifying lipid formulation for liposomal therapeutic-agent development.

The effects of buffers and pH on the thermal stability, unfolding and substrate binding of RecA.

PubMed

Metrick, Michael A; Temple, Joshua E; MacDonald, Gina

2013-12-31

The Escherichia coli protein RecA is responsible for catalysis of the strand transfer reaction used in DNA repair and recombination. Previous studies in our lab have shown that high concentrations of salts stabilize RecA in a reverse-anionic Hofmeister series. Here we investigate how changes in pH and buffer alter the thermal unfolding and cofactor binding. RecA in 20mM HEPES, MES, Tris and phosphate buffers was studied in the pH range from 6.5 to 8.5 using circular dichroism (CD), infrared (IR) and fluorescence spectroscopies. The results show all of the buffers studied stabilize RecA up to 50°C above the Tris melting temperature and influence RecA's ability to nucleate on double-stranded DNA. Infrared and CD spectra of RecA in the different buffers do not show that secondary structural changes are associated with increased stability or decreased ability to nucleate on dsDNA. These results suggest the differences in stability arise from decreasing positive charge and/or buffer interactions. © 2013. Published by Elsevier B.V. All rights reserved.

DEVELOPMENT OF BIOMARKER OF EXPOSURE TO VIRAL PATHOGENS

EPA Science Inventory

Interferon gamma (IFN-γ) was selected as a biomarker for a viral exposure study. Twelve-week-old BALB/c mice were intraperitoneally injected with 0.2ml of 104 PFU/ml of coxsackievirus B3 or B4 diluted in phosphate-buffered saline (PBS). Control mice were injected with PBS on...

Interferon Gamma as a Biomarker of Exposure to Enteric Viruses

EPA Science Inventory

Interferon gamma (IFN-γ) was selected as a biomarker for viral exposure. Twelve-week-old BALB/c mice were intraperitoneally injected with Coxsackievirus B3 or B4 diluted in phosphate-buffered saline (PBS). Control mice were injected with PBS only. Four months after viral infectio...

RELATIVE RATE CONSTANTS OF CONTAMINANT CANDIDATE LIST PESTICIDES WITH HYDROXYL RADICALS

EPA Science Inventory

The objective of this study was to establish the rate constants for the reactions of selected pesticides listed on the US EPA Contaminant Candidate List, with UV and hydroxyl radicals (·OH). Batch experiments were conducted in phosphate buffered solution at pH 7. All pestici...

ELECTROPHORETIC MOBILITIES OF ESCHERICHIA COLI 0157:H7 AND WILD-TYPE ESCHERICHIA COLI STRAINS

EPA Science Inventory

The electrophoretic mobility (EPM) of a number of human-virulent and "wild-type" Escherichia coli strains in phosphate buffered water was measured. The impact of pH, ionic strength, cation type (valence) and concentration, and bacterial strain on the EPM was investigated. Resul...

Apoptosis and Tumor Progressionin Prostate Cancer

DTIC Science & Technology

2005-02-01

control. Proc Natl Acad Sci USA 94: 10057- 10062 . 5. Colombel M, Symmans F, et al. (1993): Detection of the apoptosis-suppressing oncoprotein bcl-2 in...hours prior to treatment. After treatment, cells were washed with phosphate buffered saline ( PBS ) and fixed in 500 [tL 0.2% glutaraldehyde in water for

Influence of the chloride ion concentration on the corrosion of high-purity Mg, ZE41 and AZ91 in buffered Hank's solution.

PubMed

Taltavull, C; Shi, Z; Torres, B; Rams, J; Atrens, A

2014-02-01

This research studied the influence of the chloride ion concentration on the corrosion behaviour of high-purity magnesium (Mg) and two Mg alloys in Hank's solution, using hydrogen evolution and weight loss. A buffer based on CO2 and NaHCO3 was used to maintain the pH constant. The corrosion behaviour was governed by a partially protective surface film, and film breakdown by the chloride ions. The carbonated calcium phosphate layer that formed in Hank's solution was important in determining the protective properties of the surface film.

Direct, rapid, and label-free detection of enzyme-substrate interactions in physiological buffers using CMOS-compatible nanoribbon sensors.

PubMed

Mu, Luye; Droujinine, Ilia A; Rajan, Nitin K; Sawtelle, Sonya D; Reed, Mark A

2014-09-10

We demonstrate the versatility of Al2O3-passivated Si nanowire devices ("nanoribbons") in the analysis of enzyme-substrate interactions via the monitoring of pH change. Our approach is shown to be effective through the detection of urea in phosphate buffered saline (PBS), and penicillinase in PBS and urine, at limits of detection of <200 μM and 0.02 units/mL, respectively. The ability to extract accurate enzyme kinetics and the Michaelis-Menten constant (Km) from the acetylcholine-acetylcholinesterase reaction is also demonstrated.

Assessment of pancreas cells

NASA Technical Reports Server (NTRS)

Vanoss, C. J.

1978-01-01

Pancreatic islets were obtained from guinea pig pancreas by the collagenase method and kept alive in tissue culture prior to further studies. Pancreas cell morphology was studied by standard histochemical techniques using light microscopy. Preparative vertical electrophoresis-levitation of dispersed fetal guinea pig pancreas cells was conducted in phosphate buffer containing a heavy water (D20) gradient which does not cause clumping of cells or alter the osmolarity of the buffers. The faster migrating fractions tended to be enriched in beta-cell content. Alpha and delta cells were found to some degree in most fractions. A histogram showing the cell count distribution is included.

Effective removal of phosphate from aqueous solution using humic acid coated magnetite nanoparticles.

PubMed

Rashid, Mamun; Price, Nathaniel T; Gracia Pinilla, Miguel Ángel; O'Shea, Kevin E

2017-10-15

Effective removal of excess phosphate from water is critical to counteract eutrophication and restore water quality. In this study, low cost, environmentally friendly humic acid coated magnetite nanoparticles (HA-MNP) were synthesized and applied for the remediation of phosphate from aqueous media. The HA-MNPs, characterized by FTIR, TEM and HAADF-STEM showed the extensive coating of humic acid on the magnetite surface. The magnetic nanoparticles with diameters of 7-12 nm could be easily separated from the reaction mixture by using a simple hand held magnet. Adsorption studies demonstrate the fast and effective separation of phosphate with maximum adsorption capacity of 28.9 mg/g at pH 6.6. The adsorption behavior follows the Freundlich isotherm suggesting the formation of non-uniform multilayers of phosphate on the heterogeneous surface of HA-MNP. The adsorption kinetic fits the pseudo-second order model well with rate constants of 0.206 ± 0.003, 0.073 ± 0.002 and 0.061 ± 0.003 g mg -1 min -1 for phosphate (P) concentrations of 2, 5 and 10 mg/L respectively. The removal of phosphate was found higher at acidic and neutral pH compared to basic conditions. The nanoparticles exhibit good selectivity and adsorption efficiency for phosphate in presence of co-existing ions such as Cl - , SO 4 2- and NO 3 - with some inhibition effect by CO 3 2- . The effect of temperature on the adsorption reveals that the process is endothermic and spontaneous. HA-MNPs are promising, simple, environmentally friendly materials for the removal of phosphate from aqueous media. Copyright © 2017. Published by Elsevier Ltd.

Synthesis of Mg-Fe-Cl hydrotalcite-like nanoplatelets as an oral phosphate binder: evaluations of phosphorus intercalation activity and cellular cytotoxicity

NASA Astrophysics Data System (ADS)

Lung, Yung-Feng; Sun, Ying-Sui; Lin, Chun-Kai; Uan, Jun-Yen; Huang, Her-Hsiung

2016-09-01

The patients with end-stage of renal disease (ESRD) need to take oral phosphate binder. Traditional phosphate binders may leave the disadvantage of aluminum intoxication or cardiac calcification. Herein, Mg-Fe-Cl hydrotalcite-like nanoplatelet (HTln) is for the first time characterized as potential oral phosphate binder, with respect to its phosphorus uptake capacity in cow milk and cellular cytotoxicity. A novel method was developed for synthesizing the Mg-Fe-Cl HTln powder in different Mg2+: Fe3+ ratios where the optimization was 2.8:1. Addition of 0.5 g Mg-Fe-Cl HTln in cow milk could reduce its phosphorus content by 40% in 30 min and by 65% in 90 min. In low pH environment, the Mg-Fe-Cl HTln could exhibit relatively high performance for uptaking phosphorus. During a 90 min reaction of the HTln in milk, no phosphorus restoration occurred. In-vitro cytotoxicity assay of Mg-Fe-Cl HTln revealed no potential cellular cytotoxicity. The cells that were cultured in the HTln extract-containing media were even more viable than cells that were cultured in extract-free media (blank control). The Mg-Fe-Cl HTln extract led to hundred ppm of Mg ion and some ppm of Fe ion in the media, should be a positive effect on the good cell viability.

Optimization of microwave-assisted extraction of analgesic and anti-inflammatory drugs from human plasma and urine using response surface experimental designs.

PubMed

Fernández, Purificación; Fernández, Ana M; Bermejo, Ana M; Lorenzo, Rosa A; Carro, Antonia M

2013-04-01

The performance of microwave-assisted extraction and HPLC with photodiode array detection method for determination of six analgesic and anti-inflammatory drugs from plasma and urine, is described, optimized, and validated. Several parameters affecting the extraction technique were optimized using experimental designs. A four-factor (temperature, phosphate buffer pH 4.0 volume, extraction solvent volume, and time) hybrid experimental design was used for extraction optimization in plasma, and three-factor (temperature, extraction solvent volume, and time) Doehlert design was chosen to extraction optimization in urine. The use of desirability functions revealed the optimal extraction conditions as follows: 67°C, 4 mL phosphate buffer pH 4.0, 12 mL of ethyl acetate and 9 min, for plasma and the same volume of buffer and ethyl acetate, 115°C and 4 min for urine. Limits of detection ranged from 4 to 45 ng/mL in plasma and from 8 to 85 ng/mL in urine. The reproducibility evaluated at two concentration levels was less than 6.5% for both specimens. The recoveries were from 89 to 99% for plasma and from 83 to 99% for urine. The proposed method was successfully applied in plasma and urine samples obtained from analgesic users. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Molecular Structure and Equilibrium Forces of Bovine Submaxillary Mucin Adsorbed at a Solid-Liquid Interface.

PubMed

Zappone, Bruno; Patil, Navinkumar J; Madsen, Jan B; Pakkanen, Kirsi I; Lee, Seunghwan

2015-04-21

By combining dynamic light scattering, circular dichroism spectroscopy, atomic force microscopy, and surface force apparatus, the conformation of bovine submaxillary mucin in dilute solution and nanomechanical properties of mucin layers adsorbed on mica have been investigated. The samples were prepared by additional chromatographic purification of commercially available products. The mucin molecule was found to have a z-average hydrodynamic diameter of ca. 35 nm in phosphate buffered solution, without any particular secondary or tertiary structure. The contour length of the mucin is larger than, yet of the same order of magnitude as the diameter, indicating that the molecule can be modeled as a relatively rigid polymeric chain due to the large persistence length of the central glycosylated domain. Mucin molecules adsorbed abundantly onto mica from saline buffer, generating polymer-like, long-ranged, repulsive, and nonhysteretic forces upon compression of the adsorbed layers. Detailed analysis of such forces suggests that adsorbed mucins had an elongated conformation favored by the stiffness of the central domain. Acidification of aqueous media was chosen as means to reduce mucin-mucin and mucin-substrate electrostatic interactions. The hydrodynamic diameter in solution did not significantly change when the pH was lowered, showing that the large persistence length of the mucin molecule is due to steric hindrance between sugar chains, rather than electrostatic interactions. Remarkably, the force generated by an adsorbed layer with a fixed surface coverage also remained unaltered upon acidification. This observation can be linked to the surface-protective, pH-resistant role of bovine submaxillary mucin in the variable environmental conditions of the oral cavity.

Effect of source and particle size of supplemental phosphate on rumen function of steers fed high concentrate diets.

PubMed

Murphy, M R; Whetstone, H D; Davis, C L

1983-12-01

We examined effects of source and particle size of supplemental defluorinated rock phosphate, to meet phosphorus requirements, on rumen function of 195-kg Holstein steers fed high concentrate. Two sources and two particle sizes of each source were evaluated in a 5 X 5 Latin square with 14-day periods. There was no effect of source on ruminal mH [- log (mean (H+)]; however, ruminal mH was higher in animals fed supplements of larger particle size. This effect was also evident when rumen pH versus time curves were integrated below pH 6. Animals fed supplements of larger particle size had less area below pH 6 than those fed supplements of smaller size. Ruminal buffering capacity at pH 7 was affected by diet; however, orthogonal comparisons between treatment means were not significant. Neither source nor particle size of the supplement affected ruminal fluid osmolality, total volatile fatty acid concentration, or fecal starch. Water intake and ruminal dry matter on HyCal supplemented diets; however, there was also a trend toward increasing rumen fluid volume. The net effect was little change of dilution rate of ruminal fluid. This may explain why rumen fermentation was not affected greatly. Conventional phosphate supplements may have potential as rumen buffering agents, but higher levels of feeding should be studied.

Effects of repeated 9 and 30-day exposure to extremely low-frequency electromagnetic fields on social recognition behavior and estrogen receptors expression in olfactory bulb of Wistar female rats.

PubMed

Bernal-Mondragón, C; Arriaga-Avila, V; Martínez-Abundis, E; Barrera-Mera, B; Mercado-Gómez, O; Guevara-Guzmán, R

2017-02-01

We investigated the short- and long-term effects of extremely low-frequency electromagnetic fields (EMF) on social recognition behavior and expression of α- and β-estrogen receptors (ER). Rats were exposed to 60-Hz electromagnetic fields for 9 or 30 days and tested for social recognition behavior. Immunohistochemistry and western blot assays were performed to evaluate α- and β-ER expression in the olfactory bulb of intact, ovariectomized (OVX), and ovariectomized+estradiol (E2) replacement (OVX+E2). Ovariectomization showed impairment of social recognition after 9 days of EMF exposure and a complete recovery after E2 replacement and so did those after 30 days. Short EMF exposure increased expression of β-ER in intact, but not in the others. Longer exposure produced a decrease in intact but an increase in OVX and OVX+E2. Our findings suggest a significant role for β-estrogen receptors and a lack of effect for α-estrogen receptors on a social recognition task. EMF: extremely low frequency electromagnetic fields; ERs: estrogen receptors; OB: olfactory bulb; OVX: ovariectomized; OVX + E 2 : ovariectomized + estradiol replacement; IEI: interexposure interval; β-ER: beta estrogen receptor; E 2 : replacement of estradiol; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; WB: Western blot; PBS: phosphate-buffer saline; PB: phosphate-buffer.

Buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions: from protein buffer capacity prediction to bioprocess applications.

PubMed

Bahrenburg, Sven; Karow, Anne R; Garidel, Patrick

2015-04-01

Protein therapeutics, including monoclonal antibodies (mAbs), have significant buffering capacity, particularly at concentrations>50 mg/mL. This report addresses pH-related issues critical to adoption of self-buffered monoclonal antibody formulations. We evaluated solution conditions with protein concentrations ranging from 50 to 250 mg/mL. Samples were both buffer-free and conventionally buffered with citrate. Samples were non-isotonic or adjusted for isotonicity with NaCl or trehalose. Studies included accelerated temperature stability tests, shaking stability studies, and pH changes in infusion media as protein concentrate is added. We present averaged buffering slopes of capacity that can be applied to any mAb and present a general method for calculating buffering capacity of buffer-free, highly concentrated antibody liquid formulations. In temperature stability tests, neither buffer-free nor conventionally buffered solution conditions showed significant pH changes. Conventionally buffered solutions showed significantly higher opalescence than buffer-free ones. In general, buffer-free solution conditions showed less aggregation than conventionally buffered solutions. Shaking stability tests showed no differences between buffer-free and conventionally buffered solutions. "In-use" preparation experiments showed that pH in infusion bag medium can rapidly approximate that of self-buffered protein concentrate as concentrate is added. In summary, the buffer capacity of proteins can be predicted and buffer-free therapeutic antibody preparations provide a viable alternative to conventionally buffered solutions. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Evaluation of pink-pigmented facultative methylotrophic bacteria for phosphate solubilization.

PubMed

Jayashree, Shanmugam; Vadivukkarasi, Ponnusamy; Anand, Kirupanithi; Kato, Yuko; Seshadri, Sundaram

2011-08-01

Thirteen pink-pigmented facultative methylotrophic (PPFM) strains isolated from Adyar and Cooum rivers in Chennai and forest soil samples in Tamil Nadu, India, along with Methylobacterium extorquens, M. organophilum, M. gregans, and M. komagatae were screened for phosphate solubilization in plates. P-solubilization index of the PPFMs grown on NBRIP-BPB plates for 7 days ranged from 1.1 to 2.7. The growth of PPFMs in tricalcium phosphate amended media was found directly proportional to the glucose concentration. Higher phosphate solubilization was observed in four strains MSF 32 (415 mg l(-l)), MDW 80 (301 mg l(-l)), M. komagatae (279 mg l(-l)), and MSF 34 (202 mg l(-l)), after 7 days of incubation. A drop in the media pH from 6.6 to 3.4 was associated with an increase in titratable acidity. Acid phosphatase activity was more pronounced in the culture filtrate than alkaline phosphatase activity. Adherence of phosphate to densely grown bacterial surface was observed under scanning electron microscope after 7-day-old cultures. Biochemical characterization and screening for methanol dehydrogenase gene (mxaF) confirmed the strains as methylotrophs. The mxaF gene sequence from MSF 32 clustered towards M. lusitanum sp. with 99% similarity. This study forms the first detailed report on phosphate solubilization by the PPFMs.

Proteins contribute insignificantly to the intrinsic buffering capacity of yeast cytoplasm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poznanski, Jaroslaw; Szczesny, Pawel; Institute of Experimental Plant Biology and Biotechnology, Faculty of Biology, University of Warsaw, Warsaw

Highlights: Black-Right-Pointing-Pointer We predicted buffering capacity of yeast proteome from protein abundance data. Black-Right-Pointing-Pointer We measured total buffering capacity of yeast cytoplasm. Black-Right-Pointing-Pointer We showed that proteins contribute insignificantly to buffering capacity. -- Abstract: Intracellular pH is maintained by a combination of the passive buffering of cytoplasmic dissociable compounds and several active systems. Over the years, a large portion of and possibly most of the cell's intrinsic (i.e., passive non-bicarbonate) buffering effect was attributed to proteins, both in higher organisms and in yeast. This attribution was not surprising, given that the concentration of proteins with multiple protonable/deprotonable groups in themore » cell exceeds the concentration of free protons by a few orders of magnitude. Using data from both high-throughput experiments and in vitro laboratory experiments, we tested this concept. We assessed the buffering capacity of the yeast proteome using protein abundance data and compared it to our own titration of yeast cytoplasm. We showed that the protein contribution is less than 1% of the total intracellular buffering capacity. As confirmed with NMR measurements, inorganic phosphates play a crucial role in the process. These findings also shed a new light on the role of proteomes in maintaining intracellular pH. The contribution of proteins to the intrinsic buffering capacity is negligible, and proteins might act only as a recipient of signals for changes in pH.« less

Impact of culture media and sampling methods on Staphylococcus aureus aerosols.

PubMed

Chang, C-W; Wang, L-J

2015-10-01

Staphylococcus aureus has been detected indoors and is associated with human infection. Reliable quantification of S. aureus using a sampling technique followed by culture assay helps in assessing the risks of human exposure. The efficiency of five culture media and eight sampling methods in recovering S. aureus aerosols were evaluated. Methods to extract cells from filters were also studied. Tryptic soy agar (TSA) presented greater bacterial recovery than mannitol salt agar (MSA), CHROMagar staph aureus, Chapman stone medium, and Baird-Park agarose (P < 0.05). Moreover, 93 ± 2%-95 ± 2% and 42 ± 1%-49 ± 2% of S. aureus were, respectively, recovered by a 15-min heating of gelatin filters and 2-min vortex of polycarbonate (PC) filters. Evaluation of two filtration (IOM with gelatin filter and cassette with PC filter), two impaction (Andersen 1-STG loaded with TSA and MSA) and four impingement methods [AGI-30 and BioSampler filled with Tween mixture (TM) and phosphate-buffered saline (PBS)] revealed the BioSampler/TM performed best over 30 and 60 min of sampling (P < 0.05), while low recovery efficiencies were associated with the IOM/gelatin, cassette/PC, and AGI-30/PBS combinations (P < 0.05). In addition to BioSampler/TM, collecting S. aureus onto TSA from the Andersen 1-STG is also recommended, as it is the second best method at the 60-min sampling (P < 0.05). © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Effect of salt addition on acid resistance response of Escherichia coli O157:H7 against acetic acid.

PubMed

Bae, Young-Min; Lee, Sun-Young

2017-08-01

A combination of salt and acid is commonly used in the production of many foods, such as pickles and fermented foods. However, in our previous studies, addition of salt significantly reduced the inhibitory effect of acetic acid against E. coli O157:H7 in laboratory media and pickled cucumbers. Therefore, this study was conducted to determine the effect of salt addition on the acid resistance (AR) response of E. coli O157:H7 after treatment with acetic acid. The combined effect of acetic acid and salt showed different results depending on media tested. Organic compounds such as yeast extract and tryptone were required to observe the antagonistic effect of salt and acetic acid in combination. However, use of an rpoS mutant or addition of chloramphenicol resulted in no changes in the antagonistic effect of acetic acid and salt. The addition of glutamate to phosphate buffer significantly increased the survival levels of E. coli O157:H7 after the acetic acid treatment; however, the survival levels were lower than those after the treatment with acetic acid alone. Thus, the addition of salt may increase the AR response of E. coli O157:H7; however, these survival mechanisms were not proven clearly. Therefore, further studies need to be performed to better understand the antagonism of acetic acid salt against E. coli O157:H7. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improved chemically defined basal medium (CMRL-1969) for primary monkey kidney and human diploid cells.

PubMed

Healy, G M; Teleki, S; von Seefried, A; Walton, M J; Macmorine, H G

1971-01-01

An improved tissue culture basal medium, CMRL-1969, supplemented with serum, has been evaluated by measuring the growth responses of primary cultures of trypsin-dispersed monkey kidney cells (PMKC) and of an established culture of a human diploid cell strain (HDCS). Medium H597, an early modification of medium 199 which has been used successfully in the preparation of poliomyelitis vaccine for 15 years, was used for comparison. In addition, parallel testing was done with Basal Medium Eagle (BME) widely used for the growth of HDCS. The improvements in basal medium CMRL-1969 are attributed to changes in amino acid concentrations, in vitamin composition, and, in particular, to enhanced buffering capacity. The latter has been achieved by the use of free-base amino acids and by increasing the dibasic sodium phosphate. The new medium has already been used to advantage for the production of polioviruses in PMKC where equivalent titers were obtained from cultures initiated with 70% of the number of cells required with earlier media. The population-doubling time was reduced in this system. Also, with small inocula of HDCS, the time required to obtain maximum cell yield was shorter with CMRL-1969 than with BME. Both media were supplemented with 10% calf serum. Maximum cell yields after repeated subcultivation in the new basal medium were greatly increased and the stability of the strain, as shown by chromosomal analysis, was not affected. Basal medium CMRL-1969 can be prepared easily in liquid or powdered form.

Efficacy of disinfecting solutions in removing biofilms from polyvinyl chloride tracheostomy tubes.

PubMed

Silva, Rodrigo C; Carver, Ryan A; Ojano-Dirain, Carolyn P; Antonelli, Patrick J

2013-01-01

Bacterial biofilms are prevalent in pediatric tracheostomy tubes (TTs) and are not completely cleared by standard cleaning with gauze and household detergents. We aimed to examine the effectiveness of different disinfecting solutions to remove Staphylococcus aureus (SA) and Pseudomonas aerginosa (PA) biofilms from TTs. Prospective, controlled, in vitro microbiologic study. Uniform coupons obtained from polyvinyl chloride (PVC) pediatric TTs were briefly exposed to human plasma. The samples were incubated in growth media with either PA or SA for 7 days, and total bacterial growth was monitored by media turbidity. Five sets of 18 coupons each were exposed for 5 minutes to one of five different solutions: 2% aqueous chlorhexidine gluconate solution, 0.3% aqueous sodium hypochlorite, Polident denture cleanser, 3% hydrogen peroxide, or preservative-free phosphate-buffered saline (PBS) as a negative control. Biofilm presence was measured with bacterial counts, and surface integrity was assessed with scanning electron microscopy (SEM). All treatments significantly reduced mean SA counts (P = <.001). Sodium hypochlorite and chlorhexidine were more effective than peroxide and Polident. Chlorhexidine, sodium hypochlorite, and peroxide reduced PA counts (P = .001, .001, and .002, respectively), but Polident tabs had no significant effect. SEM revealed preserved TT surface integrity after exposure to all solutions. Disinfection with sodium hypochlorite or chlorhexidine solutions significantly reduces SA and PA biofilms on PVC TTs. Standard home care of reusable pediatric TTs may be improved by use of these readily available solutions. Copyright © 2012 The American Laryngological, Rhinological, and Otological Society, Inc.

Effects of substrates and phosphate on INT (2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyl tetrazolium chloride) and CTC (5-cyano-2,3-ditolyl tetrazolium chloride) reduction in Escherichia coli

NASA Technical Reports Server (NTRS)

Smith, J. J.; McFeters, G. A.

1996-01-01

The effects of substrates of primary aerobic dehydrogenases, and inorganic phosphate on aerobic INT and CTC reduction in Escherichia coli were examined. In general, INT produced less formazan than CTC, but INT (+) cell counts remained near values of CTC (+) cells. INT and CTC (+) cell numbers were higher than plate counts on R2A medium using succinate, formate, lactate, casamino acids, glucose, glycerol (INT only) and no substrate. Formate resulted in the greatest amount of INT and CTC formazan. Reduction of both INT and CTC was inhibited above 10 mmol l-1 phosphate, and this appeared to be related to decreased rates of O2 consumption. Formation of fluorescent CTC (+), but not INT (+) cells was also inhibited in a concentration dependent manner by phosphate above 10 mmol l-1. From light microscopic observations it appeared CTC formed increasing amounts of poorly or non-fluorescent formazan with increasing phosphate. Therefore, use of phosphate buffer in excess of 10 mmol l-1 may not be appropriate in CTC and INT reduction assays.

Effect of altered sink:source ratio on photosynthetic metabolism of source leaves

DOE Office of Scientific and Technical Information (OSTI.GOV)

Plaut, Z.; Mayoral, M.L.; Reinhold, L.

When seven crop species were grown under identical environmental conditions, decreased sink:source ratio led to a decreased photosynthetic rate within 1 to 3 days in Cucumis sativus L., Gossypium hirsutum L., and Raphanus sativus L., but not in Capsicum annuum L., Solanum melongena L., Phaseolus vulgaris L., or Ricinus communis L. The decrease was not associated with stomatal closure. In cotton and cucumbers, sink removal led to an increase in starch and sugar content, in glucose 6-phosphate and fructose 6-phosphate pools, and in the proportion of /sup 14/C detected in sugar phosphates and UDPglucose following /sup 14/CO/sub 2/ supply. Whenmore » mannose was supplied to leaf discs to sequester cytoplasmic inorganic phosphate, promotion of starch synthesis, and inhibition of CO/sub 2/ fixation, were observed in control discs, but not in discs from treated plants. Phosphate buffer reduced starch synthesis in the latter, but not the former discs. The findings suggest that sink removal led to a decreased ratio inorganic phosphate:phosphorylated compounds. In beans /sup 14/C in sugar phosphates increased following sink removal, but without sucrose accumulation, suggesting tighter feedback control of sugar level. Starch accumulated to higher levels than in the other plants, but CO/sub 2/ fixation rate was constant for several days.« less

Biodesulfurization of vanadium-bearing titanomagnetite concentrates and pH control of bioleaching solution

NASA Astrophysics Data System (ADS)

Liu, Xiao-rong; Jiang, Sheng-cai; Liu, Yan-jun; Li, Hui; Wang, Hua-jun

2013-10-01

Vanadium-bearing titanomagnetite concentrates were desulfurized with Acidithiobacillus ferrooxidans ( A. ferrooxidans). The sulfur content of the concentrates was reduced from 0.69wt% to 0.14wt% after bioleaching for 15 d with a 10% pulp density at 30°C. Maintaining a stable pH value during biodesulfurization was critical because of high acid consumption, resulting from a combination of nonoxidative and oxidative dissolution of pyrrhotite in acid solution. It is discovered that the citric acid-disodium hydrogen phosphate buffer of pH 2.0 can control the solution pH value smoothly in the optimal range of 2.0-3.0 for A. ferrooxidans growth. Using the buffer in the volume fraction range of 5.0%-15.0% stimulates A. ferrooxidans growth and improves the biodesulfurization efficiency. Compared with the buffer-free control case, the maximum increase of biodesulfurization rate is 29.7% using a 10.0vol% buffer. Bioleaching provides an alternative process for desulfurization of vanadium-bearing titanomagnetite ores.

Iron as a catalyst of human low-density lipoprotein oxidation: Critical factors involved in its oxidant properties.

PubMed

Lapenna, Domenico; Ciofani, Giuliano; Obletter, Gabriele

2017-05-01

Iron-induced human LDL oxidation, which is relevant to atherosclerosis, has not yet been properly investigated. We addressed such issue using iron(II) and (III) basically in the presence of phosphates, which are present in vivo and influence iron oxidative properties, at pH 4.5 and 7.4, representative, respectively, of the lysosomal and plasma environment. In 10mM phosphate buffered saline (PBS), iron(II) induces substantial LDL oxidation at pH 4.5 at low micromolar concentrations, while at pH 7.4 has low oxidative effects; iron(III) promotes small LDL oxidation only at pH 4.5. In 10mM sodium acetate/NaCl buffer, pH 4.5, iron-induced LDL oxidation is far higher than in PBS, highlighting the relevance of phosphates in the inhibitory modulation of iron-induced LDL oxidation. LDL oxidation is related to iron binding to the protein and lipid moiety of LDL, and requires the presence of iron(II) bound to LDL together with iron(III). Chemical modification of LDL carboxyl groups, which could bind iron especially at pH 4.5, decreases significantly iron binding to LDL and iron-induced LDL oxidation. Hydroxyl radical scavengers are ineffective on iron-induced LDL oxidation, which is inhibited by metal chelation, scavengers of alkoxyl/peroxyl radicals, or removal of LDL lipid hydroperoxides (LOOH). Overall, substantial human LDL oxidation is induced LOOH-dependently by iron(II) at pH 4.5 even in the presence of phosphates, suggesting the occurrence of iron(II)-induced LDL oxidation in vivo within lysosomes, where pH is about 4.5, iron(II) and phosphates coexist, plasma with its antioxidants is absent, and glutathione peroxidase is poorly expressed resulting in LOOH accumulation. Copyright © 2017 Elsevier GmbH. All rights reserved.

Complement, Kinins, and Hereditary Angioedema: Mechanisms of Plasma Instability when C1 Inhibitor is Absent.

PubMed

Kaplan, Allen P; Joseph, Kusumam

2016-10-01

Plasma of patients with types I and II hereditary angioedema is unstable if incubated in a plastic (i.e., inert) vessel at 37 °C manifested by progressively increasing formation of bradykinin. There is also a persistent low level of C4 in 95 % of patients even when they are symptomatic. These phenomena are due to the properties of the C1r subcomponent of C1, factor XII, and the bimolecular complex of prekallikrein with high molecular weight kininogen (HK). Purified C1r auto-activates in physiologic buffers, activates C1s, which in turn depletes C4. This occurs when C1 inhibitor is deficient. The complex of prekallikrein-HK acquires an inducible active site not present in prekallikrein which in Tris-type buffers cleaves HK stoichiometrically to release bradykinin, or in phosphate buffer auto-activates to generate kallikrein and bradykinin. Thus immunologic depletion of C1 inhibitor from factor XII-deficient plasma (phosphate is the natural buffer) auto-activates on incubation to release bradykinin. Normal C1 inhibitor prevents this from occurring. During attacks of angioedema, if factor XII auto-activates on surfaces, the initial factor XIIa formed converts prekallikrein to kallikrein, and kallikrein cleaves HK to release bradykinin. Kallikrein also rapidly activates most remaining factor XII to factor XIIa. Additional cleavages convert factor XIIa to factor XIIf and factor XIIf activates C1r enzymatically so that C4 levels approach zero, and C2 is depleted. There is also a possibility that kallikrein is generated first as a result of activation of the prekallikrein-HK complex by heat shock protein 90 released from endothelial cells, followed by kallikrein activation of factor XII.

In vitro metabolic stability of moisture-sensitive rabeprazole in human liver microsomes and its modulation by pharmaceutical excipients.

PubMed

Ren, Shan; Park, Mi-Jin; Kim, Aera; Lee, Beom-Jin

2008-03-01

A reliable method to assess in vitro metabolic stability of rabeprazole and its modulation by Generally Recognized As Safe (GRAS)-listed pharmaceutical excipients was established in human liver microsomes. The metabolic stability of rabeprazole decreased as a function of incubation time, resulting in the formation of thioether rabeprazole via nonenzymatic degradation and enzymatic metabolism. Buffer type was also a determining factor for the degree of both nonenzymatic degradation and enzymatic metabolism. The net extent of enzymatic drug metabolism, obtained by calculating the difference in drug degradation between a microsome-present reaction system and a microsome-free solution, was about 9.20 +/- 0.67% in phosphate buffer and 2.27 +/- 1.76% in Tris buffer, respectively. Rabeprazole exhibited first-order kinetics in microsome-free solution but showed non-linear kinetics in the microsome-present reaction system. The maximal velocity, Vmax, in phosphate buffer was 5.07 microg mL(-1) h(-1) and the Michaelis-Menten constant, Km, was 10.39 microg mL(-1) by computer-fitting to the classical Michaelis-Menten equation for pattern of time-dependent change in the substrate concentration. The intact drug and its thioether form were well resolved and successfully identified by HPLC chromatography and liquid chromatography mass spectroscopy (LC/MS). The metabolic stability of rabeprazole was also modulated by the presence of pharmaceutical excipients. Among the five pharmaceutical excipients tested, poloxamer 188 and Gelucire 44/14 had potentially inhibitory effects on rabeprazole metabolism in human liver microsomes (p < 0.05). A greater understanding of metabolic stability and its modulation by pharmaceutical excipients would be useful for optimizing the bioavailability of rabeprazole at the early formulation stages.

Mineral Ecology: Surface Specific Colonization and Geochemical Drivers of Biofilm Accumulation, Composition, and Phylogeny

PubMed Central

Jones, Aaron A.; Bennett, Philip C.

2017-01-01

This study tests the hypothesis that surface composition influences microbial community structure and growth of biofilms. We used laboratory biofilm reactors (inoculated with a diverse subsurface community) to explore the phylogenetic and taxonomic variability in microbial communities as a function of surface type (carbonate, silicate, aluminosilicate), media pH, and carbon and phosphate availability. Using high-throughput pyrosequencing, we found that surface type significantly controlled ~70–90% of the variance in phylogenetic diversity regardless of environmental pressures. Consistent patterns also emerged in the taxonomy of specific guilds (sulfur-oxidizers/reducers, Gram-positives, acidophiles) due to variations in media chemistry. Media phosphate availability was a key property associated with variation in phylogeny and taxonomy of whole reactors and was negatively correlated with biofilm accumulation and α-diversity (species richness and evenness). However, mineral-bound phosphate limitations were correlated with less biofilm. Carbon added to the media was correlated with a significant increase in biofilm accumulation and overall α-diversity. Additionally, planktonic communities were phylogenetically distant from those in biofilms. All treatments harbored structurally (taxonomically and phylogenetically) distinct microbial communities. Selective advantages within each treatment encouraged growth and revealed the presence of hundreds of additional operational taxonomix units (OTU), representing distinct consortiums of microorganisms. Ultimately, these results provide evidence that mineral/rock composition significantly influences microbial community structure, diversity, membership, phylogenetic variability, and biofilm growth in subsurface communities. PMID:28400754

Combining essential oils and olive extract for control of multi-drug resistant Salmonella enterica on organic leafy greens

USDA-ARS?s Scientific Manuscript database

We investigated the combined antimicrobial effects of plant essential oils and olive extract. Organic baby spinach, mature spinach, romaine lettuce, and iceberg lettuce were inoculated with the pathogen and then dip-treated in phosphate buffered saline (PBS) control, 3.0% hydrogen peroxide, a 0.1% ...

Inactivation of Hepatitis A Virus (HAV) by Chlorine and Iodine in Water

DTIC Science & Technology

1986-11-01

treatment practices utilizing chemical disinfection, primarily chlorination, are generally believed to * be effective in producing microbiologically safe...OCl) in 1 liter of HDFW. Stock solution was then diluted in tesi water (halogen demand-free, 0.01M phosphate buffer, pH 4.5, 7.0 or 9.5 in initial

Morphology of the female reproductive system and physiological age-grading of Megamelus scutellaris (Hemiptera: Delphacidae), a biological control agent of water hyacinth

USDA-ARS?s Scientific Manuscript database

The morphology of the female reproductive system in Megamelus scutellaris Berg (Hemiptera:Delphacidae), a biocontrol agent of Eichhornia crassipes (Mart.) Solms, was examined using standard light microscopy techniques. Ovaries extracted from individuals dissected in phosphate buffered saline were ex...

EFFECTS OF PH ON DECHLORINATION OF TRICHLOROETHYLENE BY ZERO-VALENT IRON

EPA Science Inventory

The reduction rates of trichloroethylene (TCE) using zero-valent iron (ZVI) and the rates of iron hydrolysis were characterized at pH values of 5 to 10. The reduction of TCE by ZVI was carried out in batch reactors filled with pH-buffered (phosphate based) solutions under anaerob...

9 CFR 113.43 - Detection of chlamydial agents.

Code of Federal Regulations, 2014 CFR

2014-01-01

... in a filed Outline of Production. (a) The yolk sac of 6-day-old chicken embryos shall be injected. Three groups of 10 embryos shall be used sequentially. (1) The inoculum for each embryo in the first... embryos shall be harvested, pooled, homogenized as a 20 percent suspension in phosphate buffered saline...

9 CFR 113.43 - Detection of chlamydial agents.

Code of Federal Regulations, 2011 CFR

2011-01-01

... in a filed Outline of Production. (a) The yolk sac of 6-day-old chicken embryos shall be injected. Three groups of 10 embryos shall be used sequentially. (1) The inoculum for each embryo in the first... embryos shall be harvested, pooled, homogenized as a 20 percent suspension in phosphate buffered saline...

9 CFR 113.43 - Detection of chlamydial agents.

Code of Federal Regulations, 2013 CFR

2013-01-01

... in a filed Outline of Production. (a) The yolk sac of 6-day-old chicken embryos shall be injected. Three groups of 10 embryos shall be used sequentially. (1) The inoculum for each embryo in the first... embryos shall be harvested, pooled, homogenized as a 20 percent suspension in phosphate buffered saline...

9 CFR 113.43 - Detection of chlamydial agents.

Code of Federal Regulations, 2012 CFR

2012-01-01

... in a filed Outline of Production. (a) The yolk sac of 6-day-old chicken embryos shall be injected. Three groups of 10 embryos shall be used sequentially. (1) The inoculum for each embryo in the first... embryos shall be harvested, pooled, homogenized as a 20 percent suspension in phosphate buffered saline...

Discernment of lint trash in raw cotton using multivariate analysis of excitation-emission luminescence spectra

USDA-ARS?s Scientific Manuscript database

Excitation-Emission luminescence spectra of basic (pH 12.5) phosphate buffer solution extracts were used to distinguish among botanical components of trash within seed cotton. All components were separated from whole plants removed from a field in southern New Mexico. Unfolded Principal Component An...

Fission Yeast Model Study for Dissection of TSC Pathway

DTIC Science & Technology

2010-04-01

prepared as follows. A total of 1010 cells were incubated at 37! for 1 hr in spheroplasts buffer [50 mm citrate–phosphate (pH 5.6) and 1.2 m sorbitol ...potassium acetate, and 0.1 m sorbitol ] containing 0.4 mm phenylmethyl- sulfonyl fluoride and 13 protease inhibitor cocktail (Nacalai Tesque) and downed

Volunteer Challenge With Enterotoxigenic Escherichia coli That Express Intestinal Colonization Factor Fimbriae CS17 and CS19

DTIC Science & Technology

2011-07-01

for 18-20 h, bacteria were harvested in sterile saline, and the sus- pension was diluted in phosphate-buffered saline to the ap- propriate...Levine MM, Merson MM. Serologic differentiation between antitoxin responses to infection with Vibrio cholerae and enterotoxin-producing Escherichia coli

Biodegradable neural cell culture sheet made of poly(lactic-co-glycolic acid) thin film with micropatterns of Dulbecco’s phosphate-buffered saline (-) containing laminin layers

NASA Astrophysics Data System (ADS)

Nakamura, Yuki; Horiuchi, Shunpu; Nishioka, Yasushiro

2018-02-01

In the regenerative medicine field of nervous systems, techniques used to fabricate microstructures of neurons on flexible and biodegradable substrates have attracted attention. In this research, biodegradable and flexible neuron culture thin films that enable the selective axonal outgrowth of neurons were fabricated using poly(lactic-co-glycolic acid) (PLGA) thin films with micropatterns of Dulbecco’s phosphate-buffered saline (D-PBS) (-) containing laminin layers. The 100-µm-thick PLGA thin films were fabricated by diluting PLGA in acetone (5% w/w) and the solution was distributed onto a poly(dimethylsiloxane) (PDMS) mold. D-PBS (-) micropatterns containing laminin layers with widths of 10-150 µm were fabricated by micromolding in capillaries (MIMIC) and the microstencil method. Rat neurons were selectively cultured for 3 d on the laminin micropatterns; using the MIMIC method, the cells properly adhered to a pattern wider than 30 µm, while with the microstencil method, the necessary pattern width for proper adhesion was more than 50 µm.

Is nothing sacred?

USGS Publications Warehouse

Hoffman, G.L.

1980-01-01

N-sodium-N-chloro-rho-toluenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes, BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species, This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, rho-toluenesulfonamide (rho-TSA), in water. The procedure involves reversed-phase (C-18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg, chloramine-T or rho-TSA/L. Mean recoveries were 96.4 +/- 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 +/- 4.6% for water samples fortified with 0.005 mg rho-TSA/L. Limits of detection without sample enrichment for chloramine-T and rho-TSA are 0.01 mg/L and 0.001 mg/L, respectively.

Liquid chromatographic determination of chloramine-T and its primary degradation product, p-toluenesulfonamide, in water

USGS Publications Warehouse

Dawson, Verdel K.; Davis, Ruth A.

1997-01-01

N-sodium-N-chloro-rho-toluenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes, BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species. This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, rho-toluenesulfonamide (rho-TSA), in water. The procedure involves reversed-phase (C-18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg, chloramine-T or rho-TSA/L. Mean recoveries were 96.4 +/- 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 +/- 4.6% for water samples fortified with 0.005 mg rho-TSA/L. Limits of detection without sample enrichment for chloramine-T and rho-TSA are 0.01 mg/L and 0.001 mg/L, respectively.

Liquid chromatographic determination of chloramine-T and its primary degradation product, p-toluenesulfonamide, in water

USGS Publications Warehouse

Dawson, V.K.; Davis, R.A.

1997-01-01

N-sodium-N-chloro-rho-toluenesulfonamide (chloramine-T) effectively controls bacterial gill disease (BGD) in cultured fishes, BGD, a common disease of hatchery-reared salmonids, causes more fish losses than any other disease among these species, This study describes a liquid chromatographic (LC) method that is capable of direct, simultaneous analysis of chloramine-T and its primary degradation product, rho-toluenesulfonamide (rho-TSA), in water. The procedure involves reversed-phase (C-18) LC analysis with ion suppression, using 0.01 M phosphate buffer at pH 3. The mobile phase is phosphate buffer-acetonitrile (60 + 40) at 1 mL/min. Both chemicals can be detected with a UV spectrophotometer at 229 nm; the method is linear up to 40 mg, chloramine-T or rho-TSA/L. Mean recoveries were 96.4 +/- 6.1% for water samples fortified with 0.03 mg chloramine-T/L and 95.3 +/- 4.6% for water samples fortified with 0.005 mg rho-TSA/L. Limits of detection without sample enrichment for chloramine-T and rho-TSA are 0.01 mg/L and 0.001 mg/L, respectively.

Development of Cell Analysis Software for Cultivated Corneal Endothelial Cells.

PubMed

Okumura, Naoki; Ishida, Naoya; Kakutani, Kazuya; Hongo, Akane; Hiwa, Satoru; Hiroyasu, Tomoyuki; Koizumi, Noriko

2017-11-01

To develop analysis software for cultured human corneal endothelial cells (HCECs). Software was designed to recognize cell borders and to provide parameters such as cell density, coefficient of variation, and polygonality of cultured HCECs based on phase contrast images. Cultured HCECs with high or low cell density were incubated with Ca-free and Mg-free phosphate-buffered saline for 10 minutes to reveal the cell borders and were then analyzed with software (n = 50). Phase contrast images showed that cell borders were not distinctly outlined, but these borders became more distinctly outlined after phosphate-buffered saline treatment and were recognized by cell analysis software. The cell density value provided by software was similar to that obtained using manual cell counting by an experienced researcher. Morphometric parameters, such as the coefficient of variation and polygonality, were also produced by software, and these values were significantly correlated with cell density (Pearson correlation coefficients -0.62 and 0.63, respectively). The software described here provides morphometric information from phase contrast images, and it enables subjective and noninvasive quality assessment for tissue engineering therapy of the corneal endothelium.

Immunological relatedness among Candida albicans and other pathogenic Candida species.

PubMed Central

Hector, R F; Lyon, F L; Domer, J E

1981-01-01

Membrane-mitochondrial (butanol-hot phosphate-buffered saline) and cytosol (soluble cytoplasmic substances) extracts from seven pathogenic species of Candida were used in in vivo and in vitro immunological assays to study antigenic similarities among the strains with respect to C. albicans. Mice were sensitized with C. albicans serotype A for footpad testing or to provide cells for lymphocyte stimulation assays, and guinea pigs were immunized with whole cells or butanol-hot phosphate-buffered saline extracts of C. albicans to obtain antisera for immunodiffusion assays. When extracts from each of the seven species were used in the assays, they consistently segregated, as determined by statistical or subjective analyses, into three groups. Extracts of C. albicans serotype A or B and C. stellatoidea were the most immunologically reactive in all assays, indicating close similarities between those two species, whereas extracts of C. tropicalis and C. parapsilosis elicited only moderate responses. Extracts from C. krusei, C. guilliermondii, and C. pseudotropicalis were hypo- or nonreactive in the assays, indicating a low level of antigenic relatedness to C. albicans. Images PMID:7037643

Clarification of the recovery mechanism of Escherichia coli after hydrostatic pressure treatment

NASA Astrophysics Data System (ADS)

Ohshima, Shuto; Nomura, Kazuki; Iwahashi, Hitoshi

2013-06-01

High hydrostatic pressure (HP) technology has gained more attention as a non-thermal food pasteurization technology. Recently, a limitation of the HP technology was reported by Koseki and Yamamoto [Recovery of Escherichia coli ATCC 25922 in phosphate buffered saline after treatment with high hydrostatic pressure. Int. J. Food Microbiol. 2006;110:108-111], who completely recovered Escherichia coli species after HP treatment. We investigated the recovery mechanism of E. coli after HP treatment. The cells were treated with 200-300 MPa at 0-25°C for 24 h. The HP-treated E. coli was recovered in phosphate-buffered saline (PBS) during 120 h of incubation at 25°C, confirming the results reported by them. However, E. coli did not grow in PBS but grew with inactivated cells in PBS. In addition, the results of our "population size experiments" demonstrated that the recovery of E. coli cells depended on both the degree of pressure and the population size. These results suggest that some portion of cells recovered from the damage and then grew by using inactivated cells.

Assessing the utility of bipolar membranes for use in photoelectrochemical water-splitting cells.

PubMed

Vargas-Barbosa, Nella M; Geise, Geoffrey M; Hickner, Michael A; Mallouk, Thomas E

2014-11-01

Membranes are important in water-splitting solar cells because they prevent crossover of hydrogen and oxygen. Here, bipolar membranes (BPMs) were tested as separators in water electrolysis cells. Steady-state membrane and solution resistances, electrode overpotentials, and pH gradients were measured at current densities relevant to solar photoelectrolysis. Under forward bias conditions, electrodialysis of phosphate buffer ions creates a pH gradient across a BPM. Under reverse bias, the BPM can maintain a constant buffer pH on both sides of the cell, but a large membrane potential develops. Thus, the BPM does not present a viable solution for electrolysis in buffered electrolytes. However, the membrane potential is minimized when the anode and cathode compartments of the cell contain strongly basic and acidic electrolytes, respectively. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Robust media processing on programmable power-constrained systems

NASA Astrophysics Data System (ADS)

McVeigh, Jeff

2005-03-01

To achieve consumer-level quality, media systems must process continuous streams of audio and video data while maintaining exacting tolerances on sampling rate, jitter, synchronization, and latency. While it is relatively straightforward to design fixed-function hardware implementations to satisfy worst-case conditions, there is a growing trend to utilize programmable multi-tasking solutions for media applications. The flexibility of these systems enables support for multiple current and future media formats, which can reduce design costs and time-to-market. This paper provides practical engineering solutions to achieve robust media processing on such systems, with specific attention given to power-constrained platforms. The techniques covered in this article utilize the fundamental concepts of algorithm and software optimization, software/hardware partitioning, stream buffering, hierarchical prioritization, and system resource and power management. A novel enhancement to dynamically adjust processor voltage and frequency based on buffer fullness to reduce system power consumption is examined in detail. The application of these techniques is provided in a case study of a portable video player implementation based on a general-purpose processor running a non real-time operating system that achieves robust playback of synchronized H.264 video and MP3 audio from local storage and streaming over 802.11.

Snow leopard (Panthera uncia) spermatozoa are sensitive to alkaline pH, but motility in vitro is not influenced by protein or energy supplements.

PubMed

Roth, T L; Swanson, W F; Collins, D; Burton, M; Garell, D M; Wildt, D E

1996-01-01

To better understand the biology of snow leopard spermatozoa and to facilitate developing assisted reproduction, a series of studies was conducted to: 1) identify the component(s) of complex culture media responsible for the detrimental effect on sperm survival in vitro, 2) optimize medium for supporting sperm viability, and 3) evaluate sperm capacitation in vitro. Constituents of complex media were added systematically to phosphate-buffered saline (PBS) to isolate the factor(s) influencing snow leopard sperm motility in vitro. Sperm capacitation was also assessed following incubation in PBS with bovine serum albumin (BSA), fetal calf serum (FCS), or heparin. For maintaining sperm motility, there was no benefit (P > or = 0.05) to supplementing PBS with low (5%) or high (20%) concentrations of snow leopard serum (SLS) versus FCS or BSA. Likewise, adding supplemental energy substrates (pyruvate, glucose, lactate, or glutamine) did not enhance or hinder (P > or = 0.05) sperm motility. However, motility rapidly decreased (P < 0.05) with the addition of NaHCO3 to PBS or Ham's F10 nutrient mixture. Surprisingly, Ham's F10 with no buffering component or with both NaHCO3 and N-Z-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) maintained sperm motility at levels similar (P > or = 0.05) to PBS. Although sperm motility in all treatments decreased with time, there was a strong inverse relationship (P < 0.01; r = 0.90) between motility and sample pH at 6 hours. Spermatozoa incubated in PBS containing FCS, BSA, or heparin did not undergo the acrosome reaction when exposed to calcium ionophore. In summary, alkaline pH has a profound detrimental effect on snow leopard sperm motility, and capacitation does not occur under conditions that normally promote this event in other felid species. These results clearly demonstrate a high degree of interspecific variation among felids in fundamental sperm function, and they provide evidence for the necessity of basic research when developing assisted reproduction in little-studied nondomestic species.

Bioequivalence study of two losartan tablet formulations with special emphasis on cardiac safety.

PubMed

Khandave, Suhas S; Sawant, Satish V; Sahane, Rakhi V; Murthi, Vivekanand; Dhanure, Shivanand S; Surve, Pradeep G

2012-05-01

To study the bioequivalence of Losartan Potassium Tablets 50 mg manufactured by Micro Labs Ltd. India to Cozaar® Tablets 50 mg, manufactured by Merck Sharp and Dohme Ltd., UK in normal healthy adult subjects under fasting condition along with the comparative safety evaluation of both treatments. The in vitro dissolution studies were carried out on 12 units each of test and reference products using the paddle method and dissolution media like water, 0.1 N hydrochloric acid with pH 1.2, pH 4.5 acetate buffer and pH 6.8 phosphate buffer. An open label, randomized, two-treatment, two-period, two-sequence, crossover bioequivalence study with a washout period of 7 days was conducted in 60 healthy Indian male subjects. Serial blood samples were collected after drug administration in each study period. Plasma concentrations of losartan and losartan acid were determined using a validated LC-MS-MS method. The pharmacokinetic parameters of losartan and losartan acid were determined using a non compartmental model. Occurrence of adverse events, change in systolic blood pressure, diastolic blood pressure, heart rate and QT interval from the baseline to 3.50 h post dose were studied and compared between the two treatments as safety parameters. The in vitro study proved the essential similarity of both the formulations as evident from the similarity factor of > 50% in all the dissolution media. The ratios for geometric least square means and 90% confidence intervals were within the acceptance criteria of 80% to 125% for log transformed C(max), AUC(0-t) and AUC(0-∞) for losartan. No statistically significant difference between the two treatments was observed for either of the safety parameters. The test product Losartan Potassium tablets 50 mg manufactured by Micro Labs Limited, India was bioequivalent to Cozaar® tablets 50 mg, manufactured by Merck Sharp and Dohme Ltd., UK in terms of rate and extent of absorption. Both treatments were well tolerated and had similar non significant effect on the safety parameters.

Formation of friable embryogenic callus in cassava is enhanced under conditions of reduced nitrate, potassium and phosphate

PubMed Central

Utsumi, Yoshinori; Utsumi, Chikako; Tanaka, Maho; Ha, Vu The; Matsui, Akihiro; Takahashi, Satoshi; Seki, Motoaki

2017-01-01

Agrobacterium-mediated transformation is an important research tool for the genetic improvement of cassava. The induction of friable embryogenic callus (FEC) is considered as a key step in cassava transformation. In the present study, the media composition was optimized for enhancing the FEC induction, and the effect of the optimized medium on gene expression was evaluated. In relative comparison to MS medium, results demonstrated that using a medium with reducing nutrition (a 10-fold less concentration of nitrogen, potassium, and phosphate), the increased amount of vitamin B1 (10 mg/L) and the use of picrolam led to reprogram non-FEC to FEC. Gene expression analyses revealed that FEC on modified media increased the expression of genes related to the regulation of polysaccharide biosynthesis and breakdown of cell wall components in comparison to FEC on normal CIM media, whereas the gene expression associated with energy flux was not dramatically altered. It is hypothesized that we reprogram non-FEC to FEC under low nitrogen, potassium and phosphate and high vitamin B1. These findings were more effective in inducing FEC formation than the previous protocol. It might contribute to development of an efficient transformation strategy in cassava. PMID:28806727

Synthesis of spherical calcium phosphate particles for dental and orthopedic applications

PubMed Central

Bohner, Marc; Tadier, Solène; van Garderen, Noémie; de Gasparo, Alex; Döbelin, Nicola; Baroud, Gamal

2013-01-01

Calcium phosphate materials have been used increasingly in the past 40 years as bone graft substitutes in the dental and orthopedic fields. Accordingly, numerous fabrication methods have been proposed and used. However, the controlled production of spherical calcium phosphate particles remains a challenge. Since such particles are essential for the synthesis of pastes and cements delivered into the host bone by minimally-invasive approaches, the aim of the present document is to review their synthesis and applications. For that purpose, production methods were classified according to the used reagents (solutions, slurries, pastes, powders), dispersion media (gas, liquid, solid), dispersion tools (nozzle, propeller, sieve, mold), particle diameters of the end product (from 10 nm to 10 mm), and calcium phosphate phases. Low-temperature calcium phosphates such as monetite, brushite or octacalcium phosphate, as well as high-temperature calcium phosphates, such as hydroxyapatite, β-tricalcium phosphate or tetracalcium phosphate, were considered. More than a dozen production methods and over hundred scientific publications were discussed. PMID:23719177

Osmotic agents and buffers in peritoneal dialysis solution: monocyte cytokine release and in vitro cytotoxicity.

PubMed

Plum, J; Schoenicke, G; Grabensee, B

1997-09-01

Peritonitis remains a major problem in peritoneal dialysis. The incidence of peritonitis may be reduced by the use of more "biocompatible" peritoneal dialysis solutions that do not impair local host defense mechanisms, such as occurs with conventional lactate-buffered glucose solutions. In the present study, we investigated the use of bicarbonate and lactate as buffer systems and glucose, amino acids, and glucose polymer as osmotic agents on specific cellular functions of isolated fresh blood monocytes in vitro. The bicarbonate-buffered solutions had a physiologic pH (7.0 to 7.6). Lactate-buffered solutions were tested with a pH between 5.5 and 7.3. RPMI 1640 (Roswell Park Memorial Institute, supplied by Biochrom, Berlin, Germany) and phosphate-buffered saline were used as control mediums. The test solutions were incubated with 200,000 monocytes/mL for 45 minutes followed by a 1:1 mix with RPMI 1640 (with supplements) during a 24- or 4-hour tetrazolium bromide test (MTT test) recovery period. Constitutive and lipopolysaccharide (LPS)-stimulated release of interleukin-1beta (IL-1beta) and IL-6 in the supernatants as parameters of cellular host defense and lactate dehydrogenase concentrations and MTT-formazan production as parameters for cell cytotoxicity were measured. Significantly higher IL-6 and IL-1beta release was found in the bicarbonate-buffered solutions, both under basal conditions and after LPS stimulation, compared with the lactate-buffered solutions (LPS stimulation: 1% amino acids/34 mmol/L bicarbonate, IL-1beta: 1,166 +/- 192 pg/mL; 1.5% glucose/34 mmol/L bicarbonate, IL-1beta: 752 +/- 107 pg/mL; 1.5% glucose/35 mmol/L lactate/pH 5.5, IL-1beta: 174 +/- 51 pg/mL). Some of these differences could even be detected in spent dialysate after a 6-hour dwell in continuous ambulatory peritoneal dialysis patients (n = 10). A lower degree of cellular cytotoxicity (lactate dehydrogenase activity) and better-preserved metabolic activity (MTT test) also were found for the bicarbonate-buffered solutions. Amino acids (1%) proved to be comparable to glucose (1.5%) as an osmotic agent at a neutral pH with regard to LPS-stimulated cytokine release and cytotoxicity. The incubation with a glucose polymer solution (7.5% glucose polymer in phosphate-buffered saline, pH 7.3) resulted in a significantly lowered cytokine release (LPS stimulation: IL-1beta, 69 +/- 19 pg/mL) compared with the other solutions with neutral pH (P < 0.01). These results suggest that bicarbonate as a buffer provided better biocompatibility with regard to mononuclear cytokine release and viability compared with lactate. Amino acids and glucose were equivalent to these parameters at a physiologic pH. The glucose polymer solution, however, was associated with a marked depression of cytokine release.

A construction of novel iron-foam-based calcium phosphate/chitosan coating biodegradable scaffold material.

PubMed

Wen, Zhaohui; Zhang, Liming; Chen, Chao; Liu, Yibo; Wu, Changjun; Dai, Changsong

2013-04-01

Slow corrosion rate and poor bioactivity restrict iron-based implants in biomedical application. In this study, we design a new iron-foam-based calcium phosphate/chitosan coating biodegradable composites offering a priority mechanical and bioactive property for bone tissue engineering through electrophoretic deposition (EPD) followed by a conversion process into a phosphate buffer solution (PBS). Tensile test results showed that the mechanical property of iron foam could be regulated through altering the construction of polyurethane foam. The priority coatings were deposited from 40% nano hydroxyapatite (nHA)/ethanol suspension mixed with 60% nHA/chitosan-acetic acid aqueous solution. In vitro immersion test showed that oxidation-iron foam as the matrix decreased the amount of iron implanted and had not influence on the bioactivity of this implant, obviously. So, this method could also be a promising method for the preparation of a new calcium phosphate/chitosan coating on foam construction. Copyright © 2012. Published by Elsevier B.V.

Formate binding near the redox-active tyrosineD in photosystem II: consequences on the properties of tyrD.

PubMed

Hienerwadel, Rainer; Gourion-Arsiquaud, Samuel; Ballottari, Matteo; Bassi, Roberto; Diner, Bruce A; Berthomieu, Catherine

2005-06-01

Formate and phosphate affect substantially the rate of tyrosine D (TyrD) oxidation and the stability of the radical TyrD* in Photosystem II [Hienerwadel R, Boussac A, Breton J and Berthomieu C (1996) Biochemistry 35: 15447-15460]. This observation prompted us to analyze the influence of formate and phosphate on the environment of TyrD using FTIR spectroscopy. The nu (CO) IR mode of TyrD* at 1503 cm-1 remains unchanged whatever the buffer used at pH 6 and whether formate is present or not in the sample. Similarly, the main IR mode of reduced TyrD remains at approximately 1250 cm-1 in all tested conditions. We thus conclude that formate does not modify the hydrogen-bonded interactions of TyrD and TyrD* with neighbouring D2His189 and D2Gln164. In the TyrD-state, an IR mode of formate significantly different from that observed in solution, is detected using 13C-formate, showing that formate forms a strong electrostatic interaction within PS II. The presence of formate affects also IR bands that may be assigned to an arginine side chain. Upon TyrD* formation, formate does not protonate but its binding interaction weakens. A proton uptake by Mes or phosphate buffer is detected, which is not observed when BisTris is used as a buffer. In these latter conditions, IR bands characteristic of the protonation of a carboxylate group of the protein are detected instead. The present IR data and the recent structural model of the TyrD environment proposed by Ferreira KN, Iverson TM, Maghlaoui K, Barber J and Iwata S [(2004) Science 303: 1831-1838], suggest that the proton released upon TyrD* formation is shared within a hydrogen bonding network including D2Arg294, and CP47Glu364 and that perturbation of this network by formate - possibly binding near D2Arg294 - substantially affects the properties of TyrD.

Non-linear hydroxyl radical formation rate in dispersions containing mixtures of pyrite and chalcopyrite particles

NASA Astrophysics Data System (ADS)

Kaur, Jasmeet; Schoonen, Martin A.

2017-06-01

The formation of hydroxyl radicals was studied in mixed pyrite-chalcopyrite dispersions in water using the conversion rate of adenine as a proxy for hydroxyl radical formation rate. Experiments were conducted as a function of pH, presence of phosphate buffer, surface loading, and pyrite-to-chalcopyrite ratio. The results indicate that hydroxyl radical formation rate in mixed systems is non-linear with respect to the rates in the pure endmember dispersions. The only exception is a set of experiments in which phosphate buffer is used. In the presence of phosphate buffer, the hydroxyl radical formation is suppressed in mixtures and the rate is close to that predicted based on the reaction kinetics of the pure endmembers. The non-linear hydroxyl radical formation in dispersions containing mixtures of pyrite and chalcopyrite is likely the result of two complementary processes. One is the fact that pyrite and chalcopyrite form a galvanic couple. In this arrangement, chalcopyrite oxidation is accelerated, while pyrite passes electrons withdrawn from chalcopyrite to molecular oxygen, the oxidant. The incomplete reduction of molecular oxygen leads to the formation of hydrogen peroxide and hydroxyl radical. The galvanic coupling appears to be augmented by the fact that chalcopyrite generates a significant amount of hydrogen peroxide upon dispersal in water. This hydrogen peroxide is then available for conversion to hydroxyl radical, which appears to be facilitated by pyrite as chalcopyrite itself produces only minor amounts of hydroxyl radical. In essence, pyrite is a ;co-factor; that facilitates the conversion of hydrogen peroxide to hydroxyl radical. This conversion reaction is a surface-mediated reaction. Given that hydroxyl radical is one of the most reactive species in nature, the formation of hydroxyl radicals in aqueous systems containing chalcopyrite and pyrite has implications for the stability of organic molecules, biomolecules, the viability of microbes, and exposure to dust containing the two metal sulfides may present a health burden.

Osteogenic Differentiation of Human and Ovine Bone Marrow Stromal Cells in response to β-Glycerophosphate and Monosodium Phosphate.

PubMed

Bottagisio, Marta; Lovati, Arianna B; Lopa, Silvia; Moretti, Matteo

2015-08-01

Bone defects are severe burdens in clinics, and thus cell therapy offers an alternative strategy exploiting the features of bone marrow stromal cells (BMSCs). Sheep are a suitable orthopedic preclinical model for similarities with humans. This study compares the influence of two phosphate sources combined with bone morphogenetic protein-2 (BMP-2) on the osteogenic potential of human and ovine BMSCs. β-Glycerophosphate (β-GlyP) and monosodium phosphate (NaH2PO4) were used as organic and inorganic phosphate sources. Osteogenic differentiation of the BMSCs was assessed by calcified matrix, alkaline phosphatase (ALP) activity, and gene expression analysis. A higher calcified matrix deposition was detected in BMSCs cultured with NaH2PO4. Although no significant differences were detected among media for human BMSCs, β-GlyP with or without BMP-2 determined a positive trend in ALP levels compared to NaH2PO4. In contrast, NaH2PO4 had a positive effect on ALP levels in ovine BMSCs. β-GlyP better supported the expression of COL1A1 in human BMSCs, whereas all media enhanced RUNX2 and SPARC expression. Ovine BMSCs responded poorly to any media for RUNX2, COL1A1, and SPARC expression. NaH2PO4 improved calcified matrix deposition without upregulating the transcriptional expression of osteogenic markers. A further optimization of differentiation protocols needs to be performed to translate the procedures from preclinical to clinical models.

Optimization of the elution buffer and concentration method for detecting hepatitis E virus in swine liver using a nested reverse transcription-polymerase chain reaction and real-time reverse transcription-polymerase chain reaction.

PubMed

Son, Na Ry; Seo, Dong Joo; Lee, Min Hwa; Seo, Sheungwoo; Wang, Xiaoyu; Lee, Bog-Hieu; Lee, Jeong-Su; Joo, In-Sun; Hwang, In-Gyun; Choi, Changsun

2014-09-01

The aim of this study was to develop an optimal technique for detecting hepatitis E virus (HEV) in swine livers. Here, three elution buffers and two concentration methods were compared with respect to enhancing recovery of HEV from swine liver samples. Real-time reverse transcription-polymerase chain reaction (RT-PCR) and nested RT-PCR were performed to detect HEV RNA. When phosphate-buffered saline (PBS, pH 7.4) was used to concentrate HEV in swine liver samples using ultrafiltration, real-time RT-PCR detected HEV in 6 of the 26 samples. When threonine buffer was used to concentrate HEV using polyethylene glycol (PEG) precipitation and ultrafiltration, real-time RT-PCR detected HEV in 1 and 3 of the 26 samples, respectively. When glycine buffer was used to concentrate HEV using ultrafiltration and PEG precipitation, real-time RT-PCR detected HEV in 1 and 3 samples of the 26 samples, respectively. When nested RT-PCR was used to detect HEV, all samples tested negative regardless of the type of elution buffer or concentration method used. Therefore, the combination of real-time RT-PCR and ultrafiltration with PBS buffer was the most sensitive and reliable method for detecting HEV in swine livers. Copyright © 2014 Elsevier B.V. All rights reserved.

Electrophoretic analysis of the major polypeptides of human erythrocyte membranes prepared by low and high osmolarity haemolysis.

PubMed

Zail, S S; Hoek, V D

1975-04-16

Human erythrocyte membranes were prepared in three ways: washing in hypotonic Tris buffer, pH 7.6, by lysis in isotonic Tris buffer pH 7.6 after incubation at 37 degrees C for 2 hours and by ultrasonication in an isotonic medium, pH 7.6. Analysis of the major polypeptides of the erythrocyte membranes by sodium dodecylsulphate polyacrylamide gel electrophoresis revealed a selective depletion of a major polypeptide representing glyceraldehyde-3-phosphate dehydrogenase in the membranes prepared by high osmolarity lysis. The pattern of seperation of the remaining polypeptides was identical in the 3 different membrane preparations.

Phosphate removal by refined aspen wood fiber treated with carboxymethyl cellulose and ferrous chloride

Treesearch

Thomas L. Eberhardt; Soo-Hong Min; James S. Han

2006-01-01

Biomass-based filtration media are of interest as an economical means to remove pollutants and nutrients found in stormwater runoff. Refined aspen wood fiber samples treated with iron salt solutions demonstrated limited capacities to remove (ortho)phosphate from test solutions. To provide additional sites for iron complex formation, and thereby impart a greater...

Striking Effects of Storage Buffers on Apparent Half-Lives of the Activity of Pseudomonas aeruginosa Arylsulfatase.

PubMed

Li, Yuwei; Yang, Xiaolan; Wang, Deqiang; Hu, Xiaolei; Yuan, Mei; Pu, Jun; Zhan, Chang-Guo; Yang, Zhaoyong; Liao, Fei

2016-08-01

To obtain the label enzyme for enzyme-linked-immunoabsorbent-assay of two components each time in one well with conventional microplate readers, molecular engineering of Pseudomonas aeruginosa arylsulfatase (PAAS) is needed. To compare thermostability of PAAS/mutants of limited purity, effects of buffers on the half-activity time (t 0.5) at 37 °C were tested. At pH 7.4, PAAS showed non-exponential decreases of activity, with the apparent t 0.5 of ~6.0 days in 50 mM HEPES, but ~42 days in 10 mM sodium borate with >85 % activity after 15 days; protein concentrations in both buffers decreased at slower rates after there were significant decreases of activities. Additionally, the apparent t 0.5 of PAAS was ~14 days in 50 mM Tris-HCl, and ~21 days in 10 mM sodium phosphate. By sodium dodecyl-polyacrylamide gel electrophoresis, the purified PAAS gave single polypeptide; after storage for 14 days at 37 °C, there were many soluble and insoluble fragmented polypeptides in the HEPES buffer, but just one principal insoluble while negligible soluble fragmented polypeptides in the borate buffer. Of tested mutants in the neutral borate buffer, rates for activity decreases and polypeptide degradation were slower than in the HEPES buffer. Hence, dilute neutral borate buffers were favorable for examining thermostability of PAAS/mutants.

Regulation of Soluble Phosphate on the Ability of Phytate Mineralization and β-Propeller Phytase Gene Expression of Pseudomonas fluorescens JZ-DZ1, a Phytate-Mineralizing Rhizobacterium.

PubMed

Shen, Lan; Wu, Xiao-Qin; Zeng, Qing-Wei; Liu, Hong-Bin

2016-12-01

Phytate-mineralizing rhizobacteria (PMR) play an important role in providing phosphorus for the sustainable plant growth. It is important to investigate the ability of PMR to produce phytase under different phosphate levels for its application. The effects of different concentrations of soluble phosphate on the ability of phytate mineralization of Pseudomonas fluorescens JZ-DZ1, a phytate-mineralizing rhizobacterium, were investigated in both solid and liquid media. The results on solid media showed that halo zone width gradually reduced with concentrations of soluble phosphate increasing from 0.05 to 20 mM, indicating the reduction of the ability of phytate mineralization. The results were consistent with the quantitative detection of phytase activity from the overall trend. An 1866-bp β-propeller phytase (BPP) gene (phyPf) was cloned from the strain, and the deduced amino acid sequence of phyPf shared 98 % of identity with a known BPP from Pseudomonas sp. BS10-3 (AJF36073.1). The results of relative real-time quantitative PCR assay showed that the expression of phyPf was induced by a low concentration (0.1 mM) of soluble phosphate, suggesting that BPP secretion was regulated by gene phyPf. The BPP-harboring bacterium P. fluorescens JZ-DZ1 with low phosphate-inducible ability of phytate mineralization could be potentially applied to promote phosphorus uptake for plants in the future.

Estimation of the Contribution of CYP2C8 and CYP3A4 in Repaglinide Metabolism by Human Liver Microsomes Under Various Buffer Conditions.

PubMed

Kudo, Toshiyuki; Goda, Hitomi; Yokosuka, Yuki; Tanaka, Ryo; Komatsu, Seina; Ito, Kiyomi

2017-09-01

We have previously reported that the microsomal activities of CYP2C8 and CYP3A4 largely depend on the buffer condition used in in vitro metabolic studies, with different patterns observed between the 2 isozymes. In the present study, therefore, the possibility of buffer condition dependence of the fraction metabolized by CYP2C8 (fm2C8) for repaglinide, a dual substrate of CYP2C8 and CYP3A4, was estimated using human liver microsomes under various buffer conditions. Montelukast and ketoconazole showed a potent and concentration-dependent inhibition of CYP2C8-mediated paclitaxel 6α-hydroxylation and CYP3A4-mediated triazolam α-hydroxylation, respectively, without dependence on the buffer condition. Repaglinide depletion was inhibited by both inhibitors, but the degree of inhibition depended on buffer conditions. Based on these results, the contribution of CYP2C8 in repaglinide metabolism was estimated to be larger than that of CYP3A4 under each buffer condition, and the fm2C8 value of 0.760, estimated in 50 mM phosphate buffer, was the closest to the value (0.801) estimated in our previous modeling analysis based on its concentration increase in a clinical drug interaction study. Researchers should be aware of the possibility of buffer condition affecting the estimated contribution of enzyme(s) in drug metabolism processes involving multiple enzymes. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Implications of the stability behavior of zinc oxide nanoparticles for toxicological studies

NASA Astrophysics Data System (ADS)

Meißner, Tobias; Oelschlägel, Kathrin; Potthoff, Annegret

2014-08-01

The increasing use of zinc oxide (ZnO) nanoparticles in sunscreens and other cosmetic products demands a risk assessment that has to be done in toxicological studies. Such investigations require profound knowledge of the behavior of ZnO in cell culture media. The current study was performed to get well-dispersed suspensions of a hydrophilic (ZnO-hydro) and a lipophilic coated (ZnO-lipo) ZnO nanomaterial for use in in vitro tests. Therefore, systematic tests were carried out with common dispersants (phosphate, lecithin, proteins) to elucidate chemical and physical changes of ZnO nanoparticles in water and physiological solutions (PBS, DMEM). Non-physiological stock suspensions were prepared using ultrasonication. Time-dependent changes of pH, conductivity, zeta potential, particle size and dissolution were recorded. Secondly, the stock suspensions were added to physiological media with or without albumin (BSA) or serum (FBS), to examine characteristics such as agglomeration and dissolution. Stable stock suspensions were obtained using phosphate as natural and physiological electrostatic stabilizing agent. Lecithin proved to be an effective wetting agent for ZnO-lipo. Although the particle size remained constant, the suspension changed over time. The pH increased as a result of ZnO dissolution and formation of zinc phosphate complexes. The behavior of ZnO in physiological media was found to depend strongly on the additives used. Applying only phosphate as additive, ZnO-hydro agglomerated within minutes. In the presence of lecithin or BSA/serum, agglomeration was inhibited. ZnO dissolution was higher under physiological conditions than in the stock suspension. Serum especially promoted this process. Using body-related dispersants (phosphate, lecithin) non-agglomerating stock suspensions of hydrophilic and lipophilic ZnO were prepared as a prerequisite to perform meaningful toxicological investigation. Both nanomaterials showed a non-negligible dissolution behavior that strongly depended on the surrounding conditions. Agglomeration of ZnO particles in physiological media is a complex function of particle coating, used dispersants and serum proteins if supplemented. The present study gives a clear guideline how to prepare and handle suspensions with ZnO for in vitro testing and allows the correlation between the chemical-physical particles behavior with findings from toxicological tests.

Quantitative and qualitative optimization of allergen extraction from peanut and selected tree nuts. Part 1. Screening of optimal extraction conditions using a D-optimal experimental design.

PubMed

L'Hocine, Lamia; Pitre, Mélanie

2016-03-01

A D-optimal design was constructed to optimize allergen extraction efficiency simultaneously from roasted, non-roasted, defatted, and non-defatted almond, hazelnut, peanut, and pistachio flours using three non-denaturing aqueous (phosphate, borate, and carbonate) buffers at various conditions of ionic strength, buffer-to-protein ratio, extraction temperature, and extraction duration. Statistical analysis showed that roasting and non-defatting significantly lowered protein recovery for all nuts. Increasing the temperature and the buffer-to-protein ratio during extraction significantly increased protein recovery, whereas increasing the extraction time had no significant impact. The impact of the three buffers on protein recovery varied significantly among the nuts. Depending on the extraction conditions, protein recovery varied from 19% to 95% for peanut, 31% to 73% for almond, 17% to 64% for pistachio, and 27% to 88% for hazelnut. A modulation by the buffer type and ionic strength of protein and immunoglobuline E binding profiles of extracts was evidenced, where high protein recovery levels did not always correlate with high immunoreactivity. Crown Copyright © 2015. Published by Elsevier Ltd. All rights reserved.

Influence of pH, buffers and role of quinolinic acid, a novel iron chelating agent, in the determination of hydroxyl radical scavenging activity of plant extracts by Electron Paramagnetic Resonance (EPR).

PubMed

Fadda, Angela; Barberis, Antonio; Sanna, Daniele

2018-02-01

The Fenton reaction is used to produce hydroxyl radicals for the evaluation of the antioxidant activity of plant extracts. In this paper the parameters affecting the production of hydroxyl radicals and their spin trapping with DMPO were studied. The use of quinolinic acid (Quin) as an Fe(II) ligand was proposed for antioxidant activity determination of Green tea, orange juice and asparagus extracts. Quin, buffers and pH affect the DMPO-OH signal intensity of the EPR spectra. Quin/Fe(II) and low pH enhance the OH generation. Phosphate and Tris-HCl buffers decrease the signal intensity measured in Fe(II)-sulfate and Fe(II)-Quin systems. The extracts were analyzed with Fenton systems containing Fe(II)-sulfate and Fe(II)-Quin with and without buffer. The highest activity was shown with Fe(II)-Quin without buffer, this system being less influenced by pH and chelating agents present in the extracts. This paper will help researchers to better design spin trapping experiments for food matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stability of glucose oxidase and catalase adsorbed on variously activated 13X zeolite.

PubMed

Pifferi, P G; Vaccari, A; Ricci, G; Poli, G; Ruggeri, O

1982-10-01

The use of 13X zeolite (0.1-0.4-mm granules), treated with 2N and 0.01N HCI, 0.01M citric acid, 0.1M citric-phosphate buffer (pH 3.6), and in untreated form to adsorb glucose oxidase of fungal origin and microbial catalase was examined. Physicochemical analysis of the support demonstrated that its crystalline structure, greatly altered by the HCl and buffer, could be partially maintained with citric acid. The specific adsorption of the enzymes increased with decreasing pH and proved to be considerable for all the supports. The stability with storage at 25 degrees C is strictly correlated with the titrable acidity of the activated zeolite expressed as meq NaOH/g and with pH value of the activation solution. It proved to be lower than 55 h for both enzymes if adsorbed on zeolite treated with 2N HCl, and 15-fold and 30-fold higher for glucose oxidase and catalase adsorbed, respectively, on zeolite treated with the 0.1M citric-phosphate buffer and 0.01M citric acid. The specific adsorption of glucose oxidase and catalase was, respectively, 1840 U/g at pH 3.0 and 6910 U/g at pH 5.0. Their half-life at 25 degrees C with storage at pH 3.5 for the former and at pH 5.0 for the latter was 800 and 1560 h vs. 40 and 110 h for the corresponding free enzymes.

Poly (Methyl Methacrylate) (PMMA) and Polyactic Acid Nanoparticles as Adjuvents for Peroral Vaccines

DTIC Science & Technology

1999-06-01

pH 7.4) 10 2 PMMA DC GA adsorbed Miglyol 10 3 PMMA DC GA adsorbed Paraffine 10 4 PMMA DC GA adsorbed Olive oil 10 5 PMMA DC GA adsorbed...polyethylenglycole, paraffin, miglyol and phosphate buffered saline. - 17 - 6.2. Testing of the Optimized Vaccine Preparations The vaccine preparations

Separation and structural analysis of saponins in a bark extract from Quillaja saponaria Molina.

PubMed

Nord, L I; Kenne, L

1999-07-20

Six major saponins were isolated from a bark extract from Quillaja saponaria Molina. Solid-phase extraction, followed by a two-step reversed-phase HPLC separation procedure with phosphate and ammonium acetate buffers of different pH values, was used. The compounds were characterised using NMR spectroscopy, mass spectrometry and chemical methods.

A simple reliable procedure for obtaining metaphases from human leukemic bone-marrow aspirates suitable for Giemsa banding.

PubMed

Srivastava, A K; Smith, R D

1980-02-01

Short incubation of heparinized human leukemic bone-marrow cells in phosphate buffered saline containing colcemid and overnight chilling of fixed cells yields metaphases with elongated and well-spread chromosomes. This technique enables us to do trypsin-Giemsa banding of chromosomes obtained from leukemic marrow cells otherwise difficult to band.

Fire-retardant-treated strandboard : properties and fire performance

Treesearch

Jerrold Winandy; Qingwen Wang; Robert H. White

2008-01-01

This study evaluated a series of single-layer, randomly oriented strandboard panels made with one resin type, a single resin loading level, and four fire-retardant-treatment levels. The fire retardant (FR) evaluated was a pH-buffered combination of boric acid and organic phosphate. Siberian larch strands were separated into five batches. One batch of strands served as...

AN ENZYME LINKED IMMUNOSORBENT ASSAY (ELISA) METHOD FOR THE URINARY BIOMONITORING OF 2,4-DICHLOROPHRENOCYACETIC ACID (2,4-D)

EPA Science Inventory

An enzyme-linked immunosorbent assay (ELISA) method was developed to quantitatively measure 2,4-dichlorophenoyacetic acid (2,4-D) in human urine. Samples were diluted (1:5) with phosphate-buffered saline, 0.05% Tween 20, with 0.02% sodium azide, and analyzed by a 96-microwekk pl...

Dominant Negative Mutants of the Estrogen Receptor as Probes of Estrogen Action and Inhibitors of Breast Cancer Growth

DTIC Science & Technology

1996-07-01

tetrazolium, inner salt; MTS; Promega], 1.9 mg/ml, and an electron coupling reagent ( phenazine methosulfate; PMS; Sigma), 0.044 mg/ml, in Dulbecco’s...acids PBS, phosphate buffered saline PCR, polymerase chain reaction PMS, phenazine methosulfate poly A, polyadenylation s.e., standard error TAE, tris

Effect of Long-Term Starvation on the Survival, Recovery, and Carbon Utilization Profiles of a Bovine Escherichia coli O157:H7 Isolate from New Zealand

PubMed Central

Morgan, Hugh W.; McDonald, Ian R.; Withers, Helen

2014-01-01

The ability to maintain a dual lifestyle of colonizing the ruminant gut and surviving in nonhost environments once shed is key to the success of Escherichia coli O157:H7 as a zoonotic pathogen. Both physical and biological conditions encountered by the bacteria are likely to change during the transition between host and nonhost environments. In this study, carbon starvation at suboptimal temperatures in nonhost environments was simulated by starving a New Zealand bovine E. coli O157:H7 isolate in phosphate-buffered saline at 4 and 15°C for 84 days. Recovery of starved cells on media with different nutrient availabilities was monitored under aerobic and anaerobic conditions. We found that the New Zealand bovine E. coli O157:H7 isolate was able to maintain membrane integrity and viability over 84 days and that the level of recovery depended on the nutrient level of the recovery medium as well as the starvation temperature. In addition, a significant difference in carbon utilization was observed between starved and nonstarved cells. PMID:24814789

Salicylyl Fluorene Derivatives as Fluorescent Sensors for Cu(II) Ions.

PubMed

Khaokeaw, Chenwit; Sukwattanasinitt, Mongkol; Rashatasakhon, Paitoon

2016-03-01

Two derivatives of fluorene containing salicylic acid groups are successfully synthesized by palladium-catalyzed coupling reactions and subsequent hydrolysis of salicylate esters. The compounds are characterized by various spectroscopic methods. In phosphate buffer (pH 8.0) solutions, these compounds are well soluble. They show maximum absorption wavelengths in the range of 304-330 nm and exhibit maximum emission wavelength around 420 and 430 nm with the quantum yields of 2.7 and 4.4 %, respectively. The compound with alkynyl salicylate groups (2) exhibits a selective fluorescence quenching towards Cu(II) and Fe(II) with a relatively similar sensitivity. The selectivity favoring Cu(II) over Fe(II) and other metal ions can be achieved upon the addition of 30 μM Triton X-100. The Cu(II) detection limit in solution phase is 1.47 ppb. The fluorescence signal recovery upon the addition of EDTA indicate a reversible complexation between 2 and Cu(II) ion. Fabrication of 2 on filter paper using a 50 μM solution in THF affords a naked-eye detection for Cu(II) and Fe(II) in aqueous media at picomole level.

Development and validation of a discriminative dissolution test for nimesulide suspensions.

PubMed

da Fonseca, Laís Bastos; Labastie, Márcio; de Sousa, Valéria Pereira; Volpato, Nadia Maria

2009-01-01

The dissolution test for oral dosage forms has recently widened to a variety of special dosage forms such as suspensions. For class II drugs, such as nimesulide (NMS), this study is very important because formulation problems may compromise drug bioavailability. In the present work, tests with four brands of commercially available NMS (RA, TS, TB, and TC) have been performed in order to study their dissolution at different conditions. The suspensions have been characterized relatively to particle size, pH, and density besides NMS assay and the amount of drug in solution in the suspension vehicles. The dissolution study was conducted using the following media: simulated intestinal fluid, pH 6.8, containing polysorbate 80 (P80) or sodium lauryl sulfate (SLS); phosphate buffer, pH 7.4, with P80 and aqueous solution of SLS. Concerning the quantitative analysis, the UV-VIS spectrophotometry could have been used in substitution to high-performance liquid chromatography since the methodology had been adequately validated. The influence of the drug particle size distribution was significant on the dissolution profiles of NMS formulations, confirming to be a factor that should be strictly controlled in the development of oral suspensions.

Synthesis and enzymatic degradation of epichlorohydrin cross-linked pectins.

PubMed

Semdé, Rasmané; Moës, André J; Devleeschouwer, Michel J; Amighi, Karim

2003-02-01

The water solubility of pectin was successfully decreased by cross-linking with increasing amounts of epichlorohydrin in the reaction media. The initial molar ratios of epichlorohydrin/ galacturonic acid monomer in the reaction mixtures were 0, 0.37, 0.56, 0.74, 1.00, 1.47, and 2.44. The resulting epichlorohydrin cross-linked pectins were thus referred to as C-LP0, C-LP37, C-LP56, C-LP75, C-LP100, C-LP150, and C-LP250, respectively. Methoxylation degrees ranged from 60.5 +/- 0.9% to 68.0 +/- 0.6%, and the effective cross-linking degrees, determined by quantification of the hydroxyl anions consumed during the reaction, were 0, 17.8, 26.0, 38.3, 46.5, 53.5, and 58.7%. respectively. After incubating the different cross-linked pectins (0.5% w/v) in 25 mL of 0.05 M acetate-phosphate buffer (pH 4.5), containing 50 microL of Pectinex Ultra SP-L (pectinolytic enzymes), between 60 and 80% of the pectin osidic bounds were broken in less than 1 hr. Moreover, increasing the cross-linking degree only resulted in a weak slowing on the enzymatic degradation velocity.

Modeling drug release from PVAc/PVP matrix tablets.

PubMed

Siepmann, F; Eckart, K; Maschke, A; Kolter, K; Siepmann, J

2010-01-25

Kollidon SR-based matrix tablets containing various amounts of diprophylline were prepared and thoroughly characterized in vitro. This includes drug release measurements in 0.1M HCl and phosphate buffer pH 7.4, monitoring of changes in the tablet's height and diameter, morphology as well as dry mass upon exposure to the release media. Based on these experimental results, a mechanistic realistic mathematical theory is proposed, taking into account the given initial and boundary conditions as well as radial and axial mass transport in cylinders. Importantly, good agreement between theory and experiment was obtained in all cases, indicating that drug diffusion with constant diffusivity is the dominant mass transport mechanism in these systems. Furthermore, the proposed theory was used to quantitatively predict the effects of the initial tablet height and diameter on the resulting drug release patterns. These theoretical predictions were compared with independently measured drug release kinetics. Good agreement was observed in all cases, proving the validity of the mathematical theory and illustrating the latter's practical benefit: The model can help to significantly facilitate the recipe optimization of this type of advanced drug delivery systems in order to achieve a desired release profile. Copyright 2009 Elsevier B.V. All rights reserved.

Anisotropic properties of the enamel organic extracellular matrix.

PubMed

do Espírito Santo, Alexandre R; Novaes, Pedro D; Line, Sérgio R P

2006-05-01

Enamel biosynthesis is initiated by the secretion, processing, and self-assembly of a complex mixture of proteins. This supramolecular ensemble controls the nucleation of the crystalline mineral phase. The detection of anisotropic properties by polarizing microscopy has been extensively used to detect macromolecular organizations in ordinary histological sections. The aim of this work was to study the birefringence of enamel organic matrix during the development of rat molar and incisor teeth. Incisor and molar teeth of rats were fixed in 2% paraformaldehyde/0.5% glutaraldehyde in 0.2 M phosphate-buffered saline (PBS), pH 7.2, and decalcified in 5% nitric acid/4% formaldehyde. After paraffin embedding, 5-microm-thick sections were obtained, treated with xylene, and hydrated. Form birefringence curves were obtained after measuring optical retardations in imbibing media, with different refractive indices. Our observations showed that enamel organic matrix of rat incisor and molar teeth is strongly birefringent, presenting an ordered supramolecular structure. The birefringence starts during the early secretion phase and disappears at the maturation phase. The analysis of enamel organic matrix birefringence may be used to detect the effects of genetic and environmental factors on the supramolecular orientation of enamel matrix and their effects on the structure of mature enamel.

Fe(III) reduction-mediated phosphate removal as vivianite (Fe3(PO4)2⋅8H2O) in septic system wastewater.

PubMed

Azam, Hossain M; Finneran, Kevin T

2014-02-01

Phosphate is a water contaminant from fertilizers, soaps, and detergents that enters municipal and onsite wastewater from households, businesses, and other commercial operations. Phosphate is a limiting nutrient for algae, and is one of the molecules that promotes eutrophication of water bodies. Phosphate is especially problematic in onsite wastewater because there are few removal mechanisms under normal operating conditions; a system must be amended specifically with compounds to bond to or adsorb phosphate in the septic tank or within the leach field. Vivianite (Fe3(PO4)2⋅8H2O) is a stable mineral formed from ferrous iron and phosphate, often as the result of Fe(III) reducing microbial activity. What was unknown was the concentration of phosphate that could be removed by this process, and whether it was relevant to mixed microbial systems like septic tank wastewater. Data presented here demonstrate that significant concentrations of phosphate (12-14mM) were removed as vivianite in growing cultures of Geobacter metallireducens strain GS-15. Vivianite precipitates were identified on the cell surfaces and within multi cell clusters using TEM-EDX; the mineral phases were directly characterized using XRD. Phosphate was also removed in dilute and raw (undiluted) septic wastewater amended with different forms of Fe(III) including solid phase and soluble Fe(III). Vivianite precipitates were recovered and identified using XRD, along with siderite (ferrous carbonate), which was expected given that the systems were likely bicarbonate buffered. These data demonstrate that ferric iron amendments in septic wastewater increase phosphate removal as the mineral vivianite, and this may be a good strategy for phosphate attenuation in the septic tank portion of onsite wastewater systems. Copyright © 2013 Elsevier Ltd. All rights reserved.

An azine based sensor for selective detection of Cu2 + ions and its copper complex for sensing of phosphate ions in physiological conditions and in living cells

NASA Astrophysics Data System (ADS)

Tiwari, Karishma; Kumar, Sumit; Kumar, Vipan; Kaur, Jeevanjot; Arora, Saroj; Mahajan, Rakesh Kumar

2018-02-01

A simple and cost effective unsymmetrical azine based Schiff base, 5-diethylamino-2-[(2-hydroxy-benzylidene)hydrazonomethyl]-phenol (1) was synthesized which selectively detect Cu2 + ions in the presence of other competitive ions through ;naked eye; in physiological conditions (EtOH-buffer (1:1, v/v, HEPES 10 mM, pH = 7.4)). The presence of Cu2 + induce color change from light yellow green to yellow with the appearance of a new band at 450 nm in UV-Vis spectra of Schiff base 1. The fluorescence of Schiff base 1 (10 μM) was quenched completely in the presence of 2.7 equiv. of Cu2 + ions. Sub-micromolar limit of detection (LOD = 3.4 × 10- 7 M), efficient Stern-Volmer quenching constant (KSV = 1.8 × 105 L mol- 1) and strong binding constant (log Kb = 5.92) has been determined with the help of fluorescence titration profile. Further, 1 - Cu2 + complex was employed for the detection of phosphate ions (PO43 -, HPO42 - and H2PO4-) at micromolar concentrations in EtOH-buffer of pH 7.4 based on fluorescence recovery due to the binding of Cu2 + with phosphate ions. Solubility at low concentration in aqueous medium, longer excitation (406 nm) and emission wavelength (537 nm), and biocompatibility of Schiff base 1 formulates its use in live cell imaging.

Investigation of folic acid stability in fortified instant noodles by use of capillary electrophoresis and reversed-phase high performance liquid chromatography.

PubMed

Hau Fung Cheung, Rodney; Morrison, Paul D; Small, Darryl M; Marriott, Philip J

2008-12-05

A single enzyme treatment with alpha-amylase, prior to the quantification of added folic acid (FA) in fortified instant fried Asian noodles with analysis performed by capillary zone electrophoresis (CZE) and reversed-phase high performance liquid chromatography (RP-HPLC) with UV detection, is described. The method was validated and optimized for capillary electrophoresis (CE) with separation achieved using a 8 mM phosphate-12 mM borate run buffer with 5% MeOH at pH 9.5. FA was well separated from matrix components with nicotinic acid (NA) employed as an internal standard. In a comparative study, separation of FA was performed using HPLC with a mobile phase consisting of 27% MeOH (v/v) in aqueous potassium phosphate buffer (3.5 mM KH(2)PO(4) and 3.2 mM K(2)HPO(4)), pH 8.5, and containing 5 mM tetrabutylammonium dihydrogen phosphate as an ion-pairing agent. For both methods, excellent results were obtained for various analytical parameters including linearity, accuracy and precision. The limit of detection was calculated to be 2.2 mg/L for CE without sample stacking and 0.10 mg/L with high performance liquid chromatography (HPLC). Sample extraction involved homogenization and enzymatic extraction with alpha-amylase. Results indicated that FA was stable during four main stages of instant fried noodle manufacturing (dough crumbs, cut sheets, steaming and frying).

The entrapment of corrosion products from CoCr implant alloys in the deposits of calcium phosphate: a comparison of serum, synovial fluid, albumin, EDTA, and water.

PubMed

Lewis, A C; Kilburn, M R; Heard, P J; Scott, T B; Hallam, K R; Allen, G C; Learmonth, I D

2006-08-01

Physical wear of orthopedic implants is inevitable. CoCr alloy samples, typically used in joint reconstruction, corrode rapidly after removal of the protective oxide layer. The behavior of CoCr pellets immersed in human serum, foetal bovine serum (FBS), synovial fluid, albumin in phosphate-buffered saline (PBS), EDTA in PBS, and water were studied using X-ray Photoelectron Spectroscopy (XPS) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS). The difference in the corrosive nature of human serum, water, albumin in PBS and synovial fluid after 5 days of immersion was highlighted by the oxide layer, which was respectively 15, 3.5, 1.5, and 1.5 nm thick. The thickness of an additional calcium phosphate deposit from human serum and synovial fluid was 40 and 2 nm, respectively. Co and Cr ions migrated from the bulk metal surface and were trapped in this deposit by the phosphate anion. This may account for the composition of wear debris from CoCr orthopedic implants, which is known to consist predominantly of hydroxy-phosphate compounds. Known components of synovial fluid including proteoglycans, pyrophosphates, phospholipids, lubricin, and superficial zone protein (SZP), have been identified as possible causes for the lack of significant calcium phosphate deposition in this environment. Circulation of these compounds around the whole implant may inhibit calcium phosphate deposition.

[Indirect and repeated electromagnetic irradiation of extremely high freguency of bacteria Escherichia coli].

PubMed

Isakhanian, V; Trchunian, A

2005-01-01

It has been shown that separate irradiation of distilled water and tris-phosphate buffer containing some inorganic ions, with Escherichia coli K12 grown in anaerobic conditions upon fermentation of sugar (glucose) with "noise" electromagnetic radiation of extremely high frequencies (53.5-68 gHz) or millimeter waves (wavelength of 3 to 8 mm) with low flux capacity (0.01 mW) for 10, 30 and 60 min caused opposite effects, changing the growth of these bacteria. The irradiation of water has a bactericide effect, whereas the irradiation of the buffer stimulates bacterial growth although the buffer itself inhibits the growth. These results point out the role of water in the bactericide action of "noise" electromagnetic radiation of extremely high frequencies, and confirm the significance of membranotropic effects. The bactericide action disappeared after repeated irradiation for 10 and 30 min with 2-h intervals. This indicates the operation of some compensatory mechanisms in bacteria.

Method And Apparatus For Arbitrarily Large Capacity Removable Media

DOEpatents

Milligan, Charles A.; Hughes, James P.; Debiez; Jacques

2003-04-08

A method and apparatus to handle multiple sets of removable media within a storage system. A first set of removable media are mounted on a set of drives. Data is accepted until the first set of removable media is filled. A second set of removable media is mounted on the drives, while the first set of removable media is removed. When the change in removable media is complete, writing of data proceeds on the second set of removable media. Data may be buffered while the change in removable media occurs. Alternatively, two sets of removable media may be mounted at the same time. When the first set of removable media is filled to a selected amount, the second set of removable media may then be used to write the data. A third set of removable media is set up or mounted for use, while the first set of removable media is removed.

Degradation of bare and silanized silicon wafer surfaces by constituents of biological fluids.

PubMed

Dekeyser, C M; Buron, C C; Derclaye, S R; Jonas, A M; Marchand-Brynaert, J; Rouxhet, P G

2012-07-15

The 24 h stability of bare silicon wafers as such or silanized with CH(3)O-(CH(2)-CH(2)-O)(n)-C(3)H(6)-trichlorosilane (n=6-9) was investigated in water, NaCl, phosphate and carbonate solutions, and in phosphate buffered saline (PBS) at 37 °C (close to biological conditions regarding temperature, high ionic strength, and pH). The resulting surfaces were analyzed using ellipsometry, X-ray Reflectometry (XRR), X-ray Photoelectron Spectroscopy (XPS), and Atomic Force Microscopy (AFM). Incubation of the silanized wafers in phosphate solution and PBS provokes a detachment of the silane layer. This is due to a hydrolysis of Si-O bonds which is favored by the action of phosphate, also responsible for a corrosion of non-silanized wafers. The surface alteration (detachment of silane layer and corrosion of the non-silanized wafer) is also important with carbonate solution, due to a higher pH (8.3). The protection of the silicon oxide layer brought by silane against the action of the salts is noticeable for phosphate but not for carbonate. Copyright © 2012 Elsevier Inc. All rights reserved.

Effect of ionic strength and presence of serum on lipoplexes structure monitorized by FRET

PubMed Central

Madeira, Catarina; Loura, Luís MS; Prieto, Manuel; Fedorov, Aleksander; Aires-Barros, M Raquel

2008-01-01

Background Serum and high ionic strength solutions constitute important barriers to cationic lipid-mediated intravenous gene transfer. Preparation or incubation of lipoplexes in these media results in alteration of their biophysical properties, generally leading to a decrease in transfection efficiency. Accurate quantification of these changes is of paramount importance for the success of lipoplex-mediated gene transfer in vivo. Results In this work, a novel time-resolved fluorescence resonance energy transfer (FRET) methodology was used to monitor lipoplex structural changes in the presence of phosphate-buffered saline solution (PBS) and fetal bovine serum. 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP)/pDNA lipoplexes, prepared in high and low ionic strength solutions, are compared in terms of complexation efficiency. Lipoplexes prepared in PBS show lower complexation efficiencies when compared to lipoplexes prepared in low ionic strength buffer followed by addition of PBS. Moreover, when serum is added to the referred formulation no significant effect on the complexation efficiency was observed. In physiological saline solutions and serum, a multilamellar arrangement of the lipoplexes is maintained, with reduced spacing distances between the FRET probes, relative to those in low ionic strength medium. Conclusion The time-resolved FRET methodology described in this work allowed us to monitor stability and characterize quantitatively the structural changes (variations in interchromophore spacing distances and complexation efficiencies) undergone by DOTAP/DNA complexes in high ionic strength solutions and in presence of serum, as well as to determine the minimum amount of potentially cytotoxic cationic lipid necessary for complete coverage of DNA. This constitutes essential information regarding thoughtful design of future in vivo applications. PMID:18302788

Radiofrequency Electric Field Heating of Conductive Media: Understanding Aqueous and Nanoparticle Heating Mechanisms and a Method for Heating Optimization

NASA Astrophysics Data System (ADS)

Lara, Nadia Chantal

Use of radiofrequency (RF) electric fields coupled with nanoparticles to enhance non-invasive hyperthermia in cancer cells and tumors sparked debate over the RF heating mechanisms of nanoparticles and the role of salts in heating. Under RF field exposure at 13.56 MHz, aqueous systems including electrolyte solutions, buffers, and blood, were shown to heat according to bulk material properties, regardless of composition. This universal aqueous heating behavior extended to suspensions of nanoparticles such as gold nanoparticles, full-length and ultra-short single-walled carbon nanotubes, and water-soluble fullerene derivatives. These suspensions displayed the same RF heating properties as saline solutions of the same conductivity, indicating that these nanoparticles themselves do not contribute to RF heating by any unique mechanism; rather, they modulate bulk conductivity, which in turn affects bulk RF heating. At 13.56 MHz, peak heating for an aqueous system occurs at a conductivity of 0.06 S/m, beyond which increases in conductivity result in reduced heating rates. Biologically relevant materials, such as blood, intra- and extracellular fluids, and most human tissues, exceed this peak heating conductivity, precluding the use of conductive materials for RF heating rate enhancement. Instead, kosmotropic or water-structuring materials, including sugars, glycols, zwitterionic molecules, and a water-soluble fullerene derivative, when added to blood or phosphate buffered saline reduced the bulk conductivity of these materials and enhanced their heating rates accordingly. A dielectric heating rate model taking into account the geometry of the sample under RF exposure was used to explain the experimental RF heating behavior of aqueous solutions and semi-aqueous materials, which generated distinct RF heating curves due to differences in bulk dielectric and physical properties.

Formulation studies for mirtazapine orally disintegrating tablets.

PubMed

Yıldız, Simay; Aytekin, Eren; Yavuz, Burçin; Bozdağ Pehlivan, Sibel; Ünlü, Nurşen

2016-01-01

Orally disintegrating tablets (ODTs) recently have gained much attention to fulfill the needs for pediatric, geriatric, and psychiatric patients with dysphagia. Aim of this study was to develop new ODT formulations containing mirtazapine, an antidepressant drug molecule having bitter taste, by using simple and inexpensive preparation methods such as coacervation, direct compression and to compare their characteristics with those of reference product (Remereon SolTab). Coacervation method was chosen for taste masking of mirtazapine. In vitro characterization studies such as diameter and thickness, weight variation, tablet hardness, tablet friability and disintegration time were performed on tablet formulations. Wetting time and in vitro dissolution tests of developed ODTs also studied using 900 mL 0.1 N HCl medium, 900 mL pH 6.8 phosphate buffer or 900 mL pH 4.5 acetate buffer at 37 ± 0.2 °C as dissolution medium. Ratio of Eudragit® E-100 was chosen as 6% (w/w) since the dissolution profile of A1 (6% Eudragit® E-100) was found closer to the reference product than A2 (4% Eudragit® E-100) and A3 (8% Eudragit® E-100). Group D, E and F formulations were presented better results in terms of disintegration time. Dissolution results indicated that Group E and F formulations showed optimum properties in all three dissolution media. Formulations D1, D4, D5, E3, E4, F1 and F5 found suitable as ODT formulations due to their favorable disintegration times and dissolution profiles. Developed mirtazapine ODTs were found promising in terms of showing the similar characteristics to the original formulation.

A phosphorus-free anolyte to enhance coulombic efficiency of microbial fuel cells

NASA Astrophysics Data System (ADS)

Tang, Xinhua; Li, Haoran; Du, Zhuwei; Ng, How Yong

2014-12-01

In this study, a phosphorus-free anolyte is prepared by using bicarbonate to replace phosphate buffer for application in two chamber microbial fuel cells (MFCs). Optical density test and Bradford protein assay shows that this phosphorus-free anolyte effectively inhibits the growth and reproduction of microorganisms suspended in the solution and greatly reduces the suspended cell mass. As a result, it considerably enhances the coulombic efficiency (CE) of MFCs. When the acetate concentration is 11 mM, the CE of the MFC using the pH 7 phosphate-containing anolyte is 9.7% and the CE with the pH 8.3 phosphate-containing anolyte is 9.1%, while the CE of the MFC using the phosphorus-free anolyte (pH 8.3) achieves 26.6%. This study demonstrates that this phosphorus-free anolyte holds the potential to enhance the feasibility for practical applications of MFCs.

Phosphorus Sorption Capacity of Gray Forest Soil as Dependent on Fertilization System

NASA Astrophysics Data System (ADS)

Rogova, O. B.; Kolobova, N. A.; Ivanov, A. L.

2018-05-01

In this paper, the results of the study of changes in the phosphorus sorption capacity of gray forest soils of Vladimir opolie under the impact of different fertilization systems are discussed. The quantitative parameters of the potential buffer capacity of soils for phosphorus (PBCP) and Langmuir sorption isotherms have been calculated. It is shown that the application of organic fertilizers results in a stronger decrease in PBCP than the application of mineral fertilizers. The portion of phosphorus of mineral compounds considerably increases, and the high content of available phosphates is maintained. In the variants with application of mineral phosphorus in combination with manure, the portions of organic and mineral phosphorus are at the level typical of unfertilized soils. The energy of phosphate bonds with the soil is minimal upon the application of a double rate of mineral phosphorus at the maximum capacity in relation to phosphate ions.

Drop Migration and Demixing of Biphasic Aqueous Systems in an Applied Electric Field

NASA Astrophysics Data System (ADS)

Todd, Paul; Raghavarao, Karumanchi S. M. S.

1999-11-01

Applying an electric field to a demixing emulsion of poly(ethylene glycol)(PEG) and dextran (or maltodextrin) in phosphate-buffered aqueous solution shortens the demixing time up to 6 fold. Phosphate ions partition into the dextran-rich phase imparting a small electrical potential between the phases. PEG-rich drops migrate cathodally, and their electrophoretic mobility is directly proportional to their radius and increases with increased ionization of phosphate. An electric field, either parallel or antiparallel to the gravity vector, can enhance demixing. A theory consistent with these observations states that drops move due to external and internal electroosmotic flow (tractor treading). Enhanced demixing in an electric field whose polarity opposes buoyancy is thought to be caused by initial increased drop growth during retardation by the electric field so that the drop becomes more buoyant. However, at infinite internal drop viscosity the theory does not extrapolate to the result for solid colloid particles.

Simultaneous HPLC analysis of pseudophedrine hydrochloride, codeine phosphate, and triprolidine hydrochloride in liquid dosage forms.

PubMed

Manassra, Adnan; Khamis, Mustafa; El-Dakiky, Magdy; Abdel-Qader, Zuhair; Al-Rimawi, Fuad

2010-03-11

An HPLC method using UV detection is proposed for the simultaneous determination of pseudophedrine hydrochloride, codeine phosphate, and triprolidine hydrochloride in liquid formulation. C18 column (250mmx4.0mm) is used as the stationary phase with a mixture of methanol:acetate buffer:acetonitrile (85:5:10, v/v) as the mobile phase. The factors affecting column separation of the analytes were studied. The calibration graphs exhibited a linear concentration range of 0.06-1.0mg/ml for pseudophedrine hydrochloride, 0.02-1.0mg/ml for codeine phosphate, and 0.0025-1.0mg/ml for triprolidine hydrochloride for a sample size of 5microl with correlation coefficients of better than 0.999 for all active ingredients studied. The results demonstrate that this method is reliable, reproducible and suitable for routine use with analysis time of less than 4min. Copyright 2009 Elsevier B.V. All rights reserved.

Nanophase iron phosphate, iron arsenate, iron vanadate, and iron molybdate minerals synthesized within the protein cage of ferritin.

PubMed

Polanams, Jup; Ray, Alisha D; Watt, Richard K

2005-05-02

Nanoparticles of iron phosphate, iron arsenate, iron molybdate, and iron vanadate were synthesized within the 8 nm interior of ferritin. The synthesis involved reacting Fe(II) with ferritin in a buffered solution at pH 7.4 in the presence of phosphate, arsenate, vanadate, or molybdate. O2 was used as the oxidant to deposit the Fe(III) mineral inside ferritin. The rate of iron incorporation into ferritin was stimulated when oxo-anions were present. The simultaneous deposition of both iron and the oxo-anion was confirmed by elemental analysis and energy-dispersive X-ray analysis. The ferritin samples containing iron and one of the oxo-anions possessed different UV/vis spectra depending on the anion used during mineral formation. TEM analysis showed mineral cores with approximately 8 nm mineral particles consistent with the formation of mineral phases inside ferritin.

Coefficient of Friction of Human Corneal Tissue.

PubMed

Wilson, Tawnya; Aeschlimann, Rudolf; Tosatti, Samuele; Toubouti, Youssef; Kakkassery, Joseph; Osborn Lorenz, Katherine

2015-09-01

A novel property evaluation methodology was used to determine the elusive value for the human corneal coefficient of friction (CoF). Using a microtribometer on 28 fresh human donor corneas with intact epithelia, the CoF was determined in 4 test solutions (≥5 corneas/solution): tear-mimicking solution (TMS) in borate-buffered saline (TMS-PS), TMS in phosphate-buffered saline (TMS-PBS), TMS with HEPES-buffered saline (TMS-HEPES), and tear-like fluid in PBS (TLF-PBS). Mean (SD) CoF values ranged from 0.006 to 0.015 and were 0.013 (0.010) in TMS-PS, 0.006 (0.003) in TMS-PBS, 0.014 (0.005) in TMS-HEPES, and 0.015 (0.009) in TLF-PBS. Statistically significant differences were shown for TMS-PBS versus TLF (P = 0.0424) and TMS-PBS versus TMS-HEPES (P = 0.0179), but not for TMS-PBS versus TMS-PS (P = 0.2389). Successful measurement of the fresh human corneal tissue CoF was demonstrated, with values differing in the evaluated buffer solutions, within this limited sample size.

Pyrroloquinoline quinone (PQQ) is reduced to pyrroloquinoline quinol (PQQH2) by vitamin C, and PQQH2 produced is recycled to PQQ by air oxidation in buffer solution at pH 7.4.

PubMed

Mukai, Kazuo; Ouchi, Aya; Nagaoka, Shin-ichi; Nakano, Masahiko; Ikemoto, Kazuto

2016-01-01

Measurements of the reaction of sodium salt of pyrroloquinoline quinone (PQQNa2) with vitamin C (Vit C) were performed in phosphate-buffered solution (pH 7.4) at 25 °C under nitrogen atmosphere, using UV-vis spectrophotometry. The absorption spectrum of PQQNa2 decreased in intensity due to the reaction with Vit C and was changed to that of pyrroloquinoline quinol (PQQH2, a reduced form of PQQ). One molecule of PQQ was reduced by two molecules of Vit C producing a molecule of PQQH2 in the buffer solution. PQQH2, thus produced, was recycled to PQQ due to air oxidation. PQQ and Vit C coexist in many biological systems, such as vegetables, fruits, as well as in human tissues. The results obtained suggest that PQQ is reduced by Vit C and functions as an antioxidant in biological systems, because it has been reported that PQQH2 shows very high free-radical scavenging and singlet-oxygen quenching activities in buffer solutions.

Internal acid buffering in San Joaquin Valley fog drops and its influence on aerosol processing

NASA Astrophysics Data System (ADS)

Collett, Jeffrey L.; Hoag, Katherine J.; Rao, Xin; Pandis, Spyros N.

Although several chemical pathways exist for S(IV) oxidation in fogs and clouds, many are self-limiting: as sulfuric acid is produced and the drop pH declines, the rates of these pathways also decline. Some of the acid that is produced can be buffered by uptake of gaseous ammonia. Additional internal buffering can result from protonation of weak and strong bases present in solution. Acid titrations of high pH fog samples (median pH=6.49) collected in California's San Joaquin Valley reveal the presence of considerable internal acid buffering. In samples collected at a rural location, the observed internal buffering could be nearly accounted for based on concentrations of ammonia and bicarbonate present in solution. In samples collected in the cities of Fresno and Bakersfield, however, significant additional, unexplained buffering was present over a pH range extending from approximately four to seven. The additional buffering was found to be associated with dissolved compounds in the fogwater. It could not be accounted for by measured concentrations of low molecular weight ( C1- C3) carboxylic acids, S(IV), phosphate, or nitrophenols. The amount of unexplained buffering in individual fog samples was found to correlate strongly with the sum of sample acetate and formate concentrations, suggesting that unmeasured organic species may be important contributors. Simulation of a Bakersfield fog episode with and without the additional, unexplained buffering revealed a significant impact on the fog chemistry. When the additional buffering was included, the simulated fog pH remained 0.3-0.7 pH units higher and the amount of sulfate present after the fog evaporated was increased by 50%. Including the additional buffering in the model simulation did not affect fogwater nitrate concentrations and was found to slightly decrease ammonium concentrations. The magnitude of the buffering effect on aqueous sulfate production is sensitive to the amount of ozone present to oxidize S(IV) in these high pH fogs.

Partial Purification and Properties of an Alkaline α-Galactosidase from Mature Leaves of Cucurbita pepo1

PubMed Central

Gaudreault, Pierre-Richard; Webb, John A.

1983-01-01

A fourth molecular from of α-galactosidase, designated LIV, an alkaline α-galactosidase, was isolated from leaves of Cucurbita pepo and purified 165-fold. It was active over a narrow pH range with optimal hydrolysis of p-nitrophenyl-α-d-galactoside and stachyose at pH 7.5. The rate of stachyose hydrolysis was 10 times that of raffinose. Km determinations in McIlvaine buffer (200 millimolar Na2-phosphate, 100 millimolar citric acid, pH 7.5) for p-nitrophenyl-α-d-galactoside, stachyose, and raffinose were 1.40, 4.5, and 36.4 millimolar, respectively. LIV was partially inhibited by Ca2+, Mg2+, and Mn2+, more so by Ni2+, Zn2+, and Co2+, and highly so by Cu2+, Ag2+, Hg2+ and by p-chloromercuribenzoate. It was not inhibited by high concentrations of the substrate p-nitrophenyl-α-d-galactoside or by myo-inositol, but α-d-galactose was a strong inhibitor. As observed for most other forms of α-galactosidase, LIV only catalyzed the hydrolysis of glycosides possessing the α-d-galactose configuration at C1, C2, and C4, and did not hydrolyze p-nitrophenyl-α-d-fucoside (α-d-galactose substituted at C6). The enzyme was highly sensitive to buffers and chelating agents. Maximum hydrolytic activity for p-nitrophenyl-α-d-galactoside was obtained in McIlvaine buffer (pH 7.5). In 10 millimolar triethanolaminehydrochloride-NaOH (pH 7.5) or 10 millimolar Hepes-NaOH (pH 7.5), hydrolytic activity was virtually eliminated, but the addition of low concentrations of either ethylenediaminetetraacetate or citrate to these buffers restored activity almost completely. Partial restoration of activity was also observed, but at higher concentrations, with pyruvate and malate. Similar effects were found for stachyose hydrolysis, but in addition some inhibition of LIV in McIlvaine buffer, possibly due to the high phosphate concentration, was observed with this substrate. It is questionable whether the organic acid anions possess any regulatory control of LIVin vivo. It was possible that the results reflected the ability of these anions, and ethylene-diaminetetraacetate, to restore LIV activity through coordination with some toxic cation introduced as a buffer contaminant. Images Fig. 1 PMID:16662884

Interaction of HEPES buffer with glass-ceramic scaffold: Can HEPES replace TRIS in SBF?

PubMed

Rohanová, Dana; Horkavcová, Diana; Paidere, Laine; Boccaccini, Aldo Roberto; Bozděchová, Pavlína; Bezdička, Petr

2018-01-01

An international standard (ISO: 23317:2014) exists for the in vitro testing of inorganic biomaterials in simulated body fluid (SBF). This standard uses TRIS buffer to maintain neutral pH in SBF, but in our previous paper, we showed that the interaction of a tested glass-ceramic material with TRIS can produce false-positive results. In this study, we evaluated whether the HEPES buffer, which also belongs to the group of Good´s buffers, would be more suitable for SBF. We compared its suitability in two media: SBF with HEPES and demineralized water with HEPES. The tested scaffold (45S5 bioactive glass-based) was exposed to the media under a static-dynamic arrangement (solutions were replaced on a daily basis) for 15 days. Leachate samples were collected daily for the analysis of Ca 2+ ions and Si (AAS), (PO 4 ) 3- ions (UV-VIS), and to measure pH. The glass-ceramic scaffold was analyzed by SEM/EDS, XRD, and WD-XRF before and after 0.3, 1, 3, 7, 11, and 15 days of exposure. Our results confirmed the rapid selective dissolution of the glass-ceramic crystalline phase (Combeite) containing Ca 2+ ions due to the presence of HEPES, hydroxyapatite supersaturation being reached within 24 h in both solutions. These new results suggest that, like TRIS, HEPES buffer is not suitable for the in vitro testing of highly reactive inorganic biomaterials (glass, glass-ceramics). The ISO standard for such tests requires revision, but HEPES is not a viable alternative to TRIS buffer. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 143-152, 2018. © 2016 Wiley Periodicals, Inc.

Comparative analyses of universal extraction buffers for assay of stress related biochemical and physiological parameters.

PubMed

Han, Chunyu; Chan, Zhulong; Yang, Fan

2015-01-01

Comparative efficiency of three extraction solutions, including the universal sodium phosphate buffer (USPB), the Tris-HCl buffer (UTHB), and the specific buffers, were compared for assays of soluble protein, free proline, superoxide radical (O2∙-), hydrogen peroxide (H2O2), and the antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), guaiacol peroxidase (POD), ascorbate peroxidase (APX), glutathione peroxidase (GPX), and glutathione reductase (GR) in Populus deltoide. Significant differences for protein extraction were detected via sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis (2-DE). Between the two universal extraction buffers, the USPB showed higher efficiency for extraction of soluble protein, CAT, GR, O2∙-, GPX, SOD, and free proline, while the UTHB had higher efficiency for extraction of APX, POD, and H2O2. When compared with the specific buffers, the USPB showed higher extraction efficiency for measurement of soluble protein, CAT, GR, and O2∙-, parallel extraction efficiency for GPX, SOD, free proline, and H2O2, and lower extraction efficiency for APX and POD, whereas the UTHB had higher extraction efficiency for measurement of POD and H2O2. Further comparisons proved that 100 mM USPB buffer showed the highest extraction efficiencies. These results indicated that USPB would be suitable and efficient for extraction of soluble protein, CAT, GR, GPX, SOD, H2O2, O2∙-, and free proline.

Deduction of a calcium ion circuit affecting rooster sperm in vitro.

PubMed

Froman, D P

2016-08-01

Four premises for rooster sperm preservation were outlined previously. Understanding mitochondrial Ca cycling in terms of whole-cell Ca flux was one premise. The present work tested the hypothesis that sperm mitochondria can be damaged by intracellular as well as extracellular Ca. Sperm were washed by centrifugation through 12% (wt/vol) Sperm were washed by centrifugation through 12%(at/vol) Accudenz to procure sperm at a physiological concentration within a chemically-defined suspension. Five solutions were tested. Each solution contained 30 m glucose, and had an osmolality of 320 mmol/kg and a pH of 7.4. Washed sperm were diluted to 2.0 × 10 sperm/mL. Each replicate sperm suspension was cooled to 10°C. Sperm mobility was measured after 1, 2, 4, 8, 12, and 24 h. Data were plotted as a function of time in each experiment. Function type was confirmed by lack of fit analysis. A parabola with a maximum at 3.7 h was observed when sperm were suspended in 205 m taurine buffered with 50 m-tris[hydroxyl-methyl]methyl-2-amino-ethanesulfonic acid (TES). This effect was attributed to a Ca flux from the nuclear envelope into mitochondria. An exponential decay was observed when TES-buffered taurine contained 2 m Ca. This effect was attributed to mitochondrial Ca overload induced by uptake of extracellular Ca. Exponential decay also was observed when TES-buffered taurine contained a Ca chelator. This effect was attributed to a Ca flux from the nuclear envelope through mitochondria and then into an extracellular Ca sink. This possibility was supported by the response of sperm to thapsigargin. Specifically, inhibition of sarcoendoplasmic reticulum Ca-ATPase compromised sperm mobility relative to a buffer control. Finally, a 60 m phosphate buffer containing 2 m citrate yielded a linear relationship in contrast to the TES-buffered solutions tested. Sperm mobility after 24 h of storage in the phosphate buffer was 92% of that observed for prewashed sperm. The linear response was attributed to weak chelators providing resistance within a Ca circuit and thereby preventing mitochondrial Ca overload. Fertility, however, was compromised when hens were inseminated with mobile sperm recovered after either 8 or 24 h of storage at 10°C. In conclusion, sperm cell Ca homeostasis was proven to be critical for maintaining sperm mobility in vitro, but mitochondrial Ca uptake is not the sole phenomenon that compromises sperm function during in vitro storage.

Improved Chemically Defined Basal Medium (CMRL-1969) for Primary Monkey Kidney and Human Diploid Cells 1

PubMed Central

Healy, G. M.; Teleki, S.; Seefried, A. V.; Walton, M. J.; Macmorine, H. G.

1971-01-01

An improved tissue culture basal medium, CMRL-1969, supplemented with serum, has been evaluated by measuring the growth responses of primary cultures of trypsin-dispersed monkey kidney cells (PMKC) and of an established culture of a human diploid cell strain (HDCS). Medium H597, an early modification of medium 199 which has been used successfully in the preparation of poliomyelitis vaccine for 15 years, was used for comparison. In addition, parallel testing was done with Basal Medium Eagle (BME) widely used for the growth of HDCS. The improvements in basal medium CMRL-1969 are attributed to changes in amino acid concentrations, in vitamin composition, and, in particular, to enhanced buffering capacity. The latter has been achieved by the use of free-base amino acids and by increasing the dibasic sodium phosphate. The new medium has already been used to advantage for the production of polioviruses in PMKC where equivalent titers were obtained from cultures initiated with 70% of the number of cells required with earlier media. The population-doubling time was reduced in this system. Also, with small inocula of HDCS, the time required to obtain maximum cell yield was shorter with CMRL-1969 than with BME. Both media were supplemented with 10% calf serum. Maximum cell yields after repeated subcultivation in the new basal medium were greatly increased and the stability of the strain, as shown by chromosomal analysis, was not affected. Basal medium CMRL-1969 can be prepared easily in liquid or powdered form. PMID:4322279

Controlled release hydrophilic matrix tablet formulations of isoniazid: design and in vitro studies.

PubMed

Hiremath, Praveen S; Saha, Ranendra N

2008-01-01

The aim of the present investigation was to develop oral controlled release matrix tablet formulations of isoniazid using hydroxypropyl methylcellulose (HPMC) as a hydrophilic release retardant polymer and to study the influence of various formulation factors like proportion of the polymer, polymer viscosity grade, compression force, and release media on the in vitro release characteristics of the drug. The formulations were developed using wet granulation technology. The in vitro release studies were performed using US Pharmacopoeia type 1 apparatus (basket method) in 900 ml of pH 7.4 phosphate buffer at 100 rpm. The release kinetics was analyzed using Korsmeyer-Peppas model. The release profiles were also analyzed using statistical method (one-way analysis of variance) and f (2) metric values. The release profiles found to follow Higuchi's square root kinetics model irrespective of the polymer ratio and the viscosity grade used. The results in the present investigation confirm that the release rate of the drug from the HPMC matrices is highly influenced by the drug/HPMC ratio and viscosity grade of the HPMC. Also, the effect of compression force and release media was found to be significant on the release profiles of isoniazid from HPMC matrix tablets. The release mechanism was found to be anomalous non-Fickian diffusion in all the cases. In the present investigation, a series of controlled release formulations of isoniazid were developed with different release rates and duration so that these formulations could further be assessed from the in vivo bioavailability studies. The formulations were found to be stable and reproducible.

Distribution of amoxicillin-resistant oral streptococci in dental plaque specimens obtained from Japanese children and adolescents at risk for infective endocarditis.

PubMed

Nemoto, Hirotoshi; Nomura, Ryota; Ooshima, Takashi; Nakano, Kazuhiko

2013-11-01

Infective endocarditis (IE) is known to be a life-threatening disease and prevention of its onset is important. Oral amoxicillin (AMPC) is generally prescribed to patients at risk for IE prior to undergoing risky procedures, such as invasive dental treatments. We previously found that approximately 5% of systemically healthy Japanese subjects harbor strains highly resistant to AMPC. In the present study, the prevalence of strains in patients at risk for IE was investigated. Thirty-four Japanese children and adolescents designated at risk for IE by their cardiovascular surgeons participated. Dental plaque specimens were obtained at recall examinations for dental checkups and placed in sterile phosphate-buffered saline, then diluted and streaked onto selective media for oral streptococci and also media containing AMPC. Nine strains with a minimum inhibitory concentration of AMPC of 16μg/mL or more were isolated from 7 of the subjects (20.6%), each of which was also resistant to other antibiotics analyzed except for new quinolone drugs. The 16S rRNA sequence of each strain demonstrated that all were oral streptococcal species. In addition, dental plaque specimens collected from 5 subjects after an additional interval of 3-4 months showed that 2 harbored the same clones at different time points. These findings suggest a higher prevalence of AMPC-resistant strains in children and adolescents at risk for IE as compared to systemically healthy subjects. Thus, alternative antibiotics should be considered for such subjects when performing prophylaxis procedures. Copyright © 2013 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.

Overloaded elution band profiles of ionizable compounds in reversed-phase liquid chromatography: Influence of the competition between the neutral and the ionic species

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gritti, Fabrice; Guiochon, Georges A

2008-01-01

The parameters that affect the shape of the band profiles of acido-basic compounds under moderately overloaded conditions (sample size less than 500 nmol for a conventional column) in RPLC are discussed. Only analytes that have a single pK{sub a} are considered. In the buffer mobile phase used for their elution, their dissociation may, under certain conditions, cause a significant pH perturbation during the passage of the band. Two consecutive injections (3.3 and 10 {micro}L) of each one of three sample solutions (0.5, 5, and 50 mM) of ten compounds were injected on five C{sub 18}-bonded packing materials, including the 5more » {micro}m Xterra-C{sub 18} (121 {angstrom}), 5 {micro}m Gemini-C{sub 18} (110 {angstrom}), 5 {micro}m Luna-C{sub 18}(2) (93 {angstrom}), 3.5 {micro}m Extend-C{sub 18} (80 {angstrom}), and 2.7 {micro}m Halo-C{sub 18} (90 {angstrom}). The mobile phase was an aqueous solution of methanol buffered at a constant {sub W}{sup W}pH of 6, with a phosphate buffer. The total concentration of the phosphate groups was constant at 50 mM. The methanol concentration was adjusted to keep all the retention factors between 1 and 10. The compounds injected were phenol, caffeine, 3-phenyl 1-propanol, 2-phenyl butyric acid, amphetamine, aniline, benzylamine, p-toluidine, procainamidium chloride, and propranololium chloride. Depending on the relative values of the analyte pK{sub a} and the buffer solution pH, these analytes elute as the neutral, the cationic, or the anionic species. The influence of structural parameters such as the charge, the size, and the hydrophobicity of the analytes on the shape of its overloaded band profile is discussed. Simple but general rules predict these shapes. An original adsorption model is proposed that accounts for the unusual peak shapes observed when the analyte is partially dissociated in the buffer solution during its elution.« less

Reduction and conversion of 2,4,6-trinitrotoluene (TNT) by sulfide under simulated anaerobic conditions.

PubMed

Qiao, Hua; Wang, He-ling; Feng, Hua-jun; Yao, Jun; Shen, Dong-sheng; Tang, Zhi-jian

2010-07-15

To account for the fast disappearance of TNT in anaerobic fermentative liquid, we investigated TNT (TNT(0)=50 mg/L) reduction by Na(2)S at 30+/-1 degrees C in two types of buffer systems, a phosphate buffer (PB, system A) and a CH(3)COOH-NaHCO(3) buffer (system B). The effects of pH, sulfide concentration and buffer system on the conversion and reaction rate of TNT were investigated. The effect of different variables on the conversion of TNT decreased in the following order: Na(2)S concentration>pH>buffer system. A kinetics study showed that TNT reduction by Na(2)S occurred in two stages separated by a change point. The observed rate constants of the first stage K(obs-1) were 1 order of magnitude lower than those of the second stage. The TNT conversion rate increased and the time to reach the change point became shorter with increasing Na(2)S concentration and pH. A 5-fold increase in Na(2)S concentration above the theoretical stoichiometric concentration was optimum. Observed rate constants of the first stage K(obs-1) were proportional to the hydrosulfide ion concentration and the conversion rate of TNT was greater and faster in buffer system B than in system A. 2010 Elsevier B.V. All rights reserved.

Evaluation of the efficiency of three extraction conditions for the immunochemical detection of allergenic soy proteins in different food matrices.

PubMed

Amponsah, Amma; Nayak, Balunkeswar

2018-04-01

Recent studies have shown the need to improve soy allergen extraction using different extraction conditions to ensure more accurate results in allergen detection. This study investigated some of these extraction conditions to confirm that these methods, especially ultrasound-assisted extraction (UAE) and the use of Laemmli buffer instead of the conventional extraction with phosphate-buffered saline (PBS), could be helpful in improving the extraction step in allergen detection. Higher total soluble protein was obtained in all samples extracted with Laemmli buffer alone and in combination with ultrasound. For immunochemical detection of soy proteins by enzyme-linked immunosorbent assay (ELISA), comparable detection was observed in extracts from all extraction conditions in all commercial samples with the exception of table cracker and veggie burger, where significantly higher detection was seen in extracts from Laemmli buffer only. For the dry mix and cookie samples, the degree of soy protein detection with ELISA varied among the different extraction conditions, but overall, extraction with only Laemmli buffer showed higher detection. Laemmli buffer with conventional extraction and UAE may be better alternatives or additional extraction methods in soy allergen detection. Different food matrices performed differently (whether it was for the recovery of total proteins or detection by ELISA) under different extraction conditions. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Recovery of Monkeys After Myocardial Infarction with Ventricular Fibrillation. Effects of PGB

DTIC Science & Technology

1980-01-01

stress5 ,0 a new bioregulatory factor was dis- ing to hypoxia and acidosis is associated with covered with the unique property of conserv- biochemical...with 5% glutaralde- bovine serum albumin to give a final mixture hyde in 0.1 M phosphate buffer, pH 7.4. At of 2.2 ml. AMP and ADP were added as 30

High-Throughput Kinetic Characterization of Ricin Toxin B Chain and Ovalbumin Antibodies Using Surface Plasmon Resonance

DTIC Science & Technology

2013-10-01

antibodies were purified using protein A purification, desalted in 1× phosphate buffered saline using Sephadex G-25 columns, and then filtered with a 0.2 µm...Purification of clones 2  The following materials were used in this process: o Protein A XK 16/15 (30 mL) column o Desalting Sephadex G

Plasma creatinine and creatine quantification by capillary electrophoresis diode array detector.

PubMed

Zinellu, Angelo; Caria, Marcello A; Tavera, Claudio; Sotgia, Salvatore; Chessa, Roberto; Deiana, Luca; Carru, Ciriaco

2005-07-15

Traditional clinical assays for nonprotein nitrogen compounds, such as creatine and creatinine, have focused on the use of enzymes or chemical reactions that allow measurement of each analyte separately. Most of these assays are mainly directed to urine quantification, so that their applicability on plasma samples is frequently hard to perform. This work describes a simple free zone capillary electrophoresis method for the simultaneous measurement of creatinine and creatine in human plasma. The effect of analytical parameters such as concentration and pH of Tris-phosphate running buffer and cartridge temperature on resolution, migration times, peak areas, and efficiency was investigated. Good separation was achieved using a 60.2-cm x 75-microm uncoated silica capillary, 75 mmol/L Tris-phosphate buffer, pH 2.25, at 15 degrees C, in less than 8 min. We compared the present method to a validated capillary electrophoresis assay, by measuring plasma creatinine in 120 normal subjects. The obtained data were compared by the Passing-Bablok regression and the Bland-Altman test. Moreover the performance of the developed method was assessed by measuring creatine and creatinine in 16 volunteers prior to and after a moderate physical exercise.

Anions in Electrothermal Supercharging of Proteins with Electrospray Ionization Follow a Reverse Hofmeister Series

PubMed Central

2015-01-01

The effects of different anions on the extent of electrothermal supercharging of proteins from aqueous ammonium and sodium salt solutions were investigated. Sulfate and hydrogen phosphate are the most effective anions at producing high charge state protein ions from buffered aqueous solution, whereas iodide and perchlorate are ineffective with electrothermal supercharging. The propensity for these anions to produce high charge state protein ions follows the following trend: sulfate > hydrogen phosphate > thiocyanate > bicarbonate > chloride > formate ≈ bromide > acetate > iodide > perchlorate. This trend correlates with the reverse Hofmeister series over a wide range of salt concentrations (1 mM to 2 M) and with several physical properties, including solvent surface tension, anion viscosity B-coefficient, and anion surface/bulk partitioning coefficient, all of which are related to the Hofmeister series. The effectiveness of electrothermal supercharging does not depend on bubble formation, either from thermal degradation of the buffer or from coalescence of dissolved gas. These results provide evidence that the effect of different ions in the formation of high charge state ions by electrothermal supercharging is largely a result of Hofmeister effects on protein stability leading to protein unfolding in the heated ESI droplet. PMID:24410546

Crystallization of dienelactone hydrolase in two space groups: structural changes caused by crystal packing

PubMed Central

Porter, Joanne L.; Carr, Paul D.; Collyer, Charles A.; Ollis, David L.

2014-01-01

Dienelactone hydrolase (DLH) is a monomeric protein with a simple α/β-hydrolase fold structure. It readily crystallizes in space group P212121 from either a phosphate or ammonium sulfate precipitation buffer. Here, the structure of DLH at 1.85 Å resolution crystallized in space group C2 with two molecules in the asymmetric unit is reported. When crystallized in space group P212121 DLH has either phosphates or sulfates bound to the protein in crucial locations, one of which is located in the active site, preventing substrate/inhibitor binding. Another is located on the surface of the enzyme coordinated by side chains from two different molecules. Crystallization in space group C2 from a sodium citrate buffer results in new crystallographic protein–protein interfaces. The protein backbone is highly similar, but new crystal contacts cause changes in side-chain orientations and in loop positioning. In regions not involved in crystal contacts, there is little change in backbone or side-chain configuration. The flexibility of surface loops and the adaptability of side chains are important factors enabling DLH to adapt and form different crystal lattices. PMID:25005082

Relationship of the method of addition and temperature of cryoprotective agents to the fertilizing capacity of cooled chicken spermatozoa.

PubMed

Sexton, T J

1975-05-01

Three experiments were conducted to determine the relationship of the method of adding (fraction or bulk) and/or holding temperature (41 degrees, 25 degrees, 10 degrees) of glycerol, dimethylsulfoxide or ethylene glycol to the fertilizing capacity of chicken spermatozoa during cooling. No significant effect on fertility was observed when sperm were washed, suspended without dilution in phosphate buffer or milk and cooled to 15 degrees in 30 min. With phosphate buffer as the medium, fertility was comparable with that of the control only when glycol was maintained at 41 degrees or 25 degrees prior to addition in fractions (3 equal parts at 10 min. intervals). Similar effects were observed when 4% DMSO at 25 degrees was added in bulk after cooling. However, when DMSO was added to sperm suspended in milk, fertility was significantly reduced regardless of treatment. None of the methods were successful in eliminating the contraceptive action of glycerol. The results indicate that a number of in vitro techniques can be used to maintain the fertilizing capacity of chicken spermatozoa in the presence of 4% ethylene glycol or DMSO.

Prefibrillar Formation Conditions of β-Lactoglobulin by Titration and Chaotropes Urea and KSCN Under Thermal Load

NASA Astrophysics Data System (ADS)

Babcock, Jeremiah; Valdez, Rolando; Brancaleon, Lorenzo

2009-10-01

The harmful growth of toxic oligomers in the formation of protein amyloid fibrils have been connected to degenerative diseases like Alzheimer's and Huntington's diseases. Understanding the fundamental mechanisms behind protein unfolding and subsequent fibrillogenesis may provide a way to stop the process from occurring. The purpose of this study was to identify favorable fibril growth conditions for a globular model protein β-lactoglobulin using the chaotropes urea and KSCN, along with titration of a pH 7.04 phosphate buffer solution at 40 ^oC over five days. Time-resolved and steady-state fluorescence was used to examine the shift in emission of the tryptophan amino acids over the applied denaturation ranges. BLG, a dimer in native form, monomerized and partially unfolded at 5 M Urea, 2 M KSCN and at pH 2 in phosphate buffer in vitro. Exposure of the solutions to continuous heat over time caused a increase in the lifetimes and red shift in the emission spectra, indicating the possible beginning of nucleation. The study has provided a base for continuation of the study of oligomerization and subsequent fibrillation of BLG, which may provide a fundamental mechanism of formation transferable to other proteins in vivo.

Morphological examination of the effects of defibrotide on experimentally induced bladder injury and its relation to interstitial cystitis.

PubMed

Aydin, H; Ercan, F; Cetinel, S; San, T

2001-08-01

This morphological study aims to investigate the effects of defibrotide, a deoxyribonucleic acid derivative drug with cytoprotective, immunosuppressive and vasorelaxant effects, on protamine sulfate induced bladder injury. Wistar albino female rats were catheterized and intravesically infused with phosphate buffered solution (control group) or, either protamine sulfate (bladder injury group) or protamine sulfate+defibrotide (bladder injury+defibrotide group) dissolved in phosphate buffered solution. The morphology of the urinary bladder was investigated using light and electron microscopy. The number of mast cells in the mucosa, mucosal alterations, intercellular junctions, surface topography and the glycosaminoglycan (GAG) layer as well as microvillus formation on the luminal surface were evaluated. In the bladder injury group, ulcerated areas, irregularity of the GAG layer, increased number of mast cells, vacuole formation, dilated perinuclear cistern, formation of pleomorphic and uniform microvilli and dilatations in the intercellular spaces in the urothelium were observed. In the bladder injury+defibrotide group a relatively normal urothelial topography, GAG layer and a few mast cells in the mucosa, some dilatations between the intercellular areas, less uniform microvilli, regular perinuclear cistern and tight junctions were observed. These results show that defibrotide can inhibit PS induced bladder damage.

Mitochondrial rhodanese: membrane-bound and complexed activity.

PubMed

Ogata, K; Volini, M

1990-05-15

We have proposed that phosphorylated and dephosphorylated forms of the mitochondrial sulfurtransferase, rhodanese, function as converter enzymes that interact with membrane-bound iron-sulfur centers of the electron transport chain to modulate the rate of mitochondrial respiration (Ogata, K., Dai, X., and Volini, M. (1989) J. Biol. Chem. 204, 2718-2725). In the present studies, we have explored some structural aspects of the mitochondrial rhodanese system. By sequential extraction of lysed mitochondria with phosphate buffer and phosphate buffer containing 20 mM cholate, we have shown that 30% of the rhodanese activity of bovine liver is membrane-bound. Resolution of cholate extracts on Sephadex G-100 indicates that part of the bound rhodanese is complexed with other mitochondrial proteins. Tests with the complex show that it forms iron-sulfur centers when incubated with the rhodanese sulfur-donor substrate thiosulfate, iron ions, and a reducing agent. Experiments on the rhodanese activity of rat liver mitochondria give similar results. Taken together, the findings indicate that liver rhodanese is in part bound to the mitochondrial membrane as a component of a multiprotein complex that forms iron-sulfur centers. The findings are consistent with the role we propose for rhodanese in the modulation of mitochondrial respiratory activity.

Sustained ophthalmic delivery of highly soluble drug using pH-triggered inner layer-embedded contact lens.

PubMed

Zhu, Qiang; Cheng, Hongbo; Huo, Yingnan; Mao, Shirui

2018-06-10

In the present work the feasibility of using inner layer-embedded contact lenses (CLs) to achieve sustained release of highly water soluble drug, betaxolol hydrochloride (BH) on the ocular surface was investigated. Blend film of cellulose acetate and Eudragit S100 was selected as the inner layer, while silicone hydrogel was used as outer layer to construct inner layer-embedded contact lenses. Influence of polymer ratio in the blend film on in vitro drug release behavior in phosphate buffered solution or simulated tear fluid was studied and drug-polymer interaction, erosion and swelling of the blend film were characterized to better understand drug-release mechanism. Storage stability of the inner layer-embedded contact lenses in phosphate buffer solution was also conducted, with ignorable drug loss and negligible change in drug release pattern within 30 days. In vivo pharmacokinetic study in rabbits showed sustained drug release for over 240 h in tear fluid, indicating prolonged drug precorneal residence time. In conclusion, cellulose acetate/Eudragit S100 inner layer-embedded contact lenses are quite promising as controlled-release carrier of highly water soluble drug for ophthalmic delivery. Copyright © 2018 Elsevier B.V. All rights reserved.

Precise method for the measurement of catalase activity in honey.

PubMed

Huidobro, José F; Sánchez, M Pilar; Muniategui, Soledad; Sancho, M Teresa

2005-01-01

An improved method is reported for the determination of catalase activity in honey. We tested different dialysis membranes, dialysis fluid compositions and amounts, dialysis temperatures, sample amounts, and dialysis times. The best results were obtained by dialysis of 7.50 g sample in a cellulose dialysis sack, using two 3 L portions of 0.015 M sodium phosphate buffer (pH 7.0) as the dialysis fluid at 4 degrees C for 22 h. As in previous methods, catalase activity was determined on the basis of the rate of disappearance of the substrate, H202, with the H202 determined spectrophotometrically at 400 nm in an assay system containing o-dianisidine and peroxidase. Trials indicated that the best solvent for the o-dianisidine was 0.2 M sodium phosphate buffer, pH 6.1; the best starting H202 concentration was 3 mM; the best HCl concentration for stopping the reaction was 6 N; and the best sample volume for catalase measurement was 7.0 mL. Precision values (relative standard deviations for analyses of 10 subsamples of each of 3 samples) were high, ranging from 0.48% for samples with high catalase activity to 1.98% for samples with low catalase activity.

Increasing binding density of yeast cells by control of surface charge with allylamine grafting to ion modified polymer surfaces.

PubMed

Tran, Clara T H; Kondyurin, Alexey; Chrzanowski, Wojciech; Bilek, Marcela M M; McKenzie, David R

2014-10-01

Plasma immersion ion implantation (PIII) treatment of polymers creates a biointerface capable of direct covalent immobilization of biomolecules. The immobilization of protein molecules is achieved by covalent bonds formed between embedded radicals on the treated surface and amino acid side chains and cells can be immobilized through cell-wall proteins. The attachment density of negatively charged entities on a PIII treated surface is inhibited by its negative surface charge at neutral pH. To reduce the negative charge of PIII treated surfaces in phosphate buffer (pH 7.4, 11mM), we develop an effective approach of grafting allylamine monomers onto the treated surface. The results reveal reactions between allylamine and radicals on the PIII treated surface. One of these triggers polymerization, increasing the number of amine groups grafted. As a consequence, the PIII treated polystyrene surface after allylamine exposure becomes more hydrophobic and less negatively charged in phosphate buffer. Using yeast cells as an example, we have shown a significant improvement (6-15 times) of cell density immobilized on the PIII treated surface after exposure to allylamine. Copyright © 2014 Elsevier B.V. All rights reserved.

[Screening, identification and phosphate-solubilizing characteristics of phosphate-solubilizing bacteria strain D2 (Pantoea sp.)in rhizosphere of Pinus tabuliformis in iron tailings yard.

PubMed

Wang, Jun Juan; Yan, Ai Hua; Wang, Wei; Li, Ji Quan; Li, Yu Ling

2016-11-18

Two strains of phosphate-solubilizing bacteria were isolated from the rhizosphere of Pinus tabuliformis in iron tailings vegetation restoration areas in Malan Town, Qianan City, Hebei Pro-vince. The bacterial strain D2 with strong phosphate-solubilizing capacity was obtained via screening with plate and shake flask. Based on the morphology, physiology and biochemistry, and the sequence analysis of 16S rDNA, the D2 was identified as a member of Pantoea sp. A fermentation experiment was conducted to investigate the effect of carbon and nitrogen sources on the phosphate-solubilizing capacity of the strain D2; under different nitrogen sources, the organic acids in liquid culture, as well as their types and contents were determined by high performance liquid chromatography. The results showed that the strain D2 was capable of efficiently solubilizing tricalcium phosphate, and the highest value of available phosphorus was up to 392.13 mg·L -1 in liquid culture. The strain D2 displayed the strongest phosphate-solubilizing capability when glucose and ammonium sulfate were used as carbon and nitrogen sources in the culture media, respectively. Under varied nitrogen sources, the resulting organic acids and their types and contents were different. When the nitrogen source in culture media was ammonium sulfate, ammonium chloride, potassium nitrate, sodium nitrate or ammonium nitrate, all four organic acids, including oxalic acid, formic acid, acetic acid and citric acid, were produced. In addition, malic acid was uniquely produced when ammonium sulfate, ammonium chloride or ammonium nitrate was used as the nitrogen source. By Pearson's correlation analysis, a significant positive correlation between the acetic acid content and the available phosphorus content was found (r=0.886, P<0.05), suggesting that acetic acid produced by strain D2 played an important role in promoting inorganic phosphorus dissolution, which was most likely to be one of the important phosphate-solubilizing mechanisms of the strain.

Medium pH, carbon and nitrogen concentrations modulate the phosphate solubilization efficiency of Penicillium purpurogenum through organic acid production.

PubMed

Scervino, J M; Papinutti, V L; Godoy, M S; Rodriguez, M A; Della Monica, I; Recchi, M; Pettinari, M J; Godeas, A M

2011-05-01

To study phosphate solubilization in Penicillium purpurogenum as function of medium pH, and carbon and nitrogen concentrations. Tricalcium phosphate (CP) solubilization efficiency of P. purpurogenum was evaluated at acid or alkaline pH using different C and N sources. Glucose- and (NH(4) )(2) SO(4) -based media showed the highest P solubilization values followed by fructose. P. purpurogenum solubilizing ability was higher in cultures grown at pH 6·5 than cultures at pH 8·5. Organic acids were detected in both alkaline and neutral media, but the relative percentages of each organic acid differed. Highest P release coincided with the highest organic acids production peak, especially gluconic acid. When P. purpurogenum grew in alkaline media, the nature and concentration of organic acids changed at different N and C concentrations. A factorial categorical experimental design showed that the highest P-solubilizing activity, coinciding with the highest organic acid production, corresponded to the highest C concentration and lowest N concentration. The results described in the present study show that medium pH and carbon and nitrogen concentrations modulate the P solubilization efficiency of P. purpurogenum through the production of organic acids and particularly that of gluconic acid. In the P solubilization optimization studies, glucose and (NH(4) )(2) SO(4) as C and N sources allowed a higher solubilization efficiency at high pH. This organism is a potentially proficient soil inoculant, especially in P-poor alkaline soils where other P solubilizers fail to release soluble P. Further work is necessary to elucidate whether these results can be extrapolated to natural soil ecosystems, where different pH values are present. Penicillium purpurogenum could be used to develop a bioprocess for the manufacture of phosphatic fertilizer with phosphate calcium minerals. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Combining ligand design and photo-ligation to provide optimal quantum dot-bioconjugates for sensing and imaging

NASA Astrophysics Data System (ADS)

Zhan, Naiqian; Palui, Goutam; Safi, Malak; Mattoussi, Hedi

2014-03-01

We describe the design and synthesis of two metal-coordinating zwitterion ligands to promote the transfer of hydrophobic QDs to buffer media over broad range of conditions. The ligands are prepared by appending either one or two lipoic acid anchoring groups onto a zwitterion, LA-TEG200-ZW and bis(LA)- ZW. Combining these ligands with a photochemical reduction of the lipoic acid group in the presence of UV irradiation, provides an easy to implement method to transfer luminescent QDs to buffer media, while preserving their optical and spectroscopic properties intact. The resulting zwitterion-QDs have very thin capping shell, which allows their self-assembly with full size proteins via metal-to-histidine coordination. These conjugates have great potential for use in various bio-motivated applications.

Bicarbonate alters cellular responses in respiration assays.

PubMed

Krycer, James R; Fisher-Wellman, Kelsey H; Fazakerley, Daniel J; Muoio, Deborah M; James, David E

2017-08-05

Metabolic assay buffers often omit bicarbonate, which is susceptible to alkalinisation in an open environment. Here, we assessed the effect of including bicarbonate in respirometry experiments. By supplementing HEPES-buffered media with low concentrations of bicarbonate, we found increased respiration in adipocytes and hepatocytes, but not myotubes. This was observed across multiple respirometry platforms and was independent of effects on enhanced insulin sensitivity, pH drift, or mitochondrial function. Permeabilised cell experiments suggest that bicarbonate increases substrate availability, likely by acting as a cofactor for carboxylase enzymes. This emphasises the importance of buffer choice in experimental biology. Copyright © 2017 Elsevier Inc. All rights reserved.

Imaging the Drosophila retina: zwitterionic buffers PIPES and HEPES induce morphological artifacts in tissue fixation.

PubMed

Nie, Jing; Mahato, Simpla; Zelhof, Andrew C

2015-02-03

Tissue fixation is crucial for preserving the morphology of biological structures and cytological details to prevent postmortem degradation and autolysis. Improper fixation conditions could lead to artifacts and thus incorrect conclusions in immunofluorescence or histology experiments. To resolve reported structural anomalies with respect to Drosophila photoreceptor cell organization we developed and utilized a combination of live imaging and fixed samples to investigate the exact biogenesis and to identify the underlying source for the reported discrepancies in structure. We found that piperazine-N,N'-bis(ethanesulfonic acid) (PIPES) and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES), two zwitterionic buffers commonly used in tissue fixation, can cause severe lumen and cell morphological defects in Drosophila pupal and adult retina; the inter-rhabdomeral lumen becomes dilated and the photoreceptor cells are significantly reduced in size. Correspondingly, the localization pattern of Eyes shut (EYS), a luminal protein, is severely altered. In contrast, tissues fixed in the phosphate buffered saline (PBS) buffer results in lumen and cell morphologies that are consistent with live imaging. We suggest that PIPES and HEPES buffers should be utilized with caution for fixation when examining the interplay between cells and their extracellular environment, especially in Drosophila pupal and adult retina research.

Driving forces and the influence of the buffer composition on the complexation reaction between ibuprofen and HPCD.

PubMed

Perlovich, German L; Skar, Merete; Bauer-Brandl, Annette

2003-10-01

Cyclodextrins are often used in order to increase the aqueous solubility of drug substances by complexation. In order to investigate the complexation reaction of ibuprofen and hydroxypropyl-beta-cyclodextrin, titration calorimetry was used as a direct method. The thermodynamic parameters of the complexation process (stability constant, K(11); complexation enthalpy, deltaH(c) degrees ) were obtained in two different buffer systems (citric acid/sodium-phosphate and phosphoric acid) at various pH values. Based on these data the relative contributions of the enthalpic and entropic terms of the Gibbs energy to the complexation process have been analyzed. In both buffers the enthalpic and entropic terms are of different sign and this case corresponds to a 'nonclassical' model of hydrophobic interaction. In citric buffer, the main driving force of complexation is the entropy, which increases from 60 to 67% while the pH of the solution increases from 3.2 to 8.0. However, for the phosphoric buffer the entropic term decreases from 60 to 45%, while the pH-value of the solution increases from 5.0 to 8.2, and the driving force of the complexation process changes from entropy to enthalpy. The experimental data of the present study are compared to results of other authors and discrepancies discussed in detail.

Optimization of protein solution by a novel experimental design method using thermodynamic properties.

PubMed

Kim, Nam Ah; An, In Bok; Lee, Sang Yeol; Park, Eun-Seok; Jeong, Seong Hoon

2012-09-01

In this study, the structural stability of hen egg white lysozyme in solution at various pH levels and in different types of buffers, including acetate, phosphate, histidine, and Tris, was investigated by means of differential scanning calorimetry (DSC). Reasonable pH values were selected from the buffer ranges and were analyzed statistically through design of experiment (DoE). Four factors were used to characterize the thermograms: calorimetric enthalpy (ΔH), temperature at maximum heat flux (T( m )), van't Hoff enthalpy (ΔH( V )), and apparent activation energy of protein solution (E(app)). It was possible to calculate E(app) through mathematical elaboration from the Lumry-Eyring model by changing the scan rate. The transition temperature of protein solution, T( m ), increased when the scan rate was faster. When comparing the T( m ), ΔH( V ), ΔH, and E(app) of lysozyme in various pH ranges and buffers with different priorities, lysozyme in acetate buffer at pH 4.767 (scenario 9) to pH 4.969 (scenario 11) exhibited the highest thermodynamic stability. Through this experiment, we found a significant difference in the thermal stability of lysozyme in various pH ranges and buffers and also a new approach to investigate the physical stability of protein by DoE.

Continuous analysis of phosphate in a Greenland shallow ice core

NASA Astrophysics Data System (ADS)

Kjær, Helle Astrid; Svensson, Anders; Bigler, Matthias; Vallelonga, Paul; Kettner, Ernesto; Dahl-Jensen, Dorthe

2010-05-01

Phosphate is an important and sometimes limiting nutrient for primary production in the oceans. Because of deforestation and the use of phosphate as a fertilizer changes in the phosphate cycle have occurred over the last centuries. On longer time scales, sea level changes are thought to have also caused changes in the phosphate cycle. Analyzing phosphate concentrations in ice cores may help to gain important knowledge about those processes. In the present study, we attach a phosphate detection line to an existing continuous flow analysis (CFA) setup for ice core analysis at the University of Copenhagen. The CFA system is optimized for high-resolution measurements of insoluble dust particles, electrolytic melt water conductivity, and the concentrations of ammonium and sodium. For the phosphate analysis we apply a continuous and highly sensitive absorption method that has been successfully applied to determine phosphate concentrations of sea water (Zhang and Chi, 2002). A line of melt water from the CFA melt head (1.01 ml per minute) is combined with a molybdate blue reagent and an ascorbic acid buffer. An uncompleted reaction takes place in five meters of heated mixing coils before the absorption measurement at a wavelength of 710 nanometer takes place in a 2 m long liquid waveguide cell (LWCC) with an inner volume of 0.5 ml. The method has a detection limit of around 0.1 ppb and we are currently investigating a possible interference from molybdate reacting with silicates that are present in low amounts in the ice. Preliminary analysis of early Holocene samples from the NGRIP ice core show phosphate concentration values of a few ppb. In this study, we will attempt to determine past levels of phosphate in a shallow Northern Greenland firn core with an annual layer thickness of about 20 cm ice equivalent. With a melt speed of 2.5 cm ice per minute our method should allow the resolution of any seasonal variability in phosphate concentrations.

Dietary and genetic evidence for phosphate toxicity accelerating mammalian aging

PubMed Central

Ohnishi, Mutsuko; Razzaque, M. Shawkat

2010-01-01

Identifying factors that accelerate the aging process can provide important therapeutic targets for slowing down this process. Misregulation of phosphate homeostasis has been noted in various skeletal, cardiac, and renal diseases, but the exact role of phosphate toxicity in mammalian aging is not clearly defined. Phosphate is widely distributed in the body and is involved in cell signaling, energy metabolism, nucleic acid synthesis, and the maintenance of acid-base balance by urinary buffering. In this study, we used an in vivo genetic approach to determine the role of phosphate toxicity in mammalian aging. Klotho-knockout mice (klotho−/−) have a short life span and show numerous physical, biochemical, and morphological features consistent with premature aging, including kyphosis, uncoordinated movement, hypogonadism, infertility, severe skeletal muscle wasting, emphysema, and osteopenia, as well as generalized atrophy of the skin, intestine, thymus, and spleen. Molecular and biochemical analyses suggest that increased renal activity of sodium-phosphate cotransporters (NaPi2a) leads to severe hyperphosphatemia in klotho−/− mice. Genetically reducing serum phosphate levels in klotho−/− mice by generating a NaPi2a and klotho double-knockout (NaPi2a−/−/klotho−/−) strain resulted in amelioration of premature aging-like features. The NaPi2a−/−/klotho−/− double-knockout mice regained reproductive ability, recovered their body weight, reduced their organ atrophy, and suppressed ectopic calcifications, with the resulting effect being prolonged survival. More important, when hyperphosphatemia was induced in NaPi2a−/−/klotho−/− mice by feeding with a high-phosphate diet, premature aging-like features reappeared, clearly suggesting that phosphate toxicity is the main cause of premature aging in klotho−/− mice. The results of our dietary and genetic manipulation studies provide in vivo evidence for phosphate toxicity accelerating the aging process and suggest a novel role for phosphate in mammalian aging.—Ohnishi, M., Razzaque, M. S. Dietary and genetic evidence for phosphate toxicity accelerating mammalian aging. PMID:20418498

Determination of josamycin residues in porcine tissues using high-performance liquid chromatography with pre-column derivatization and spectrofluorimetric detection.

PubMed

Leroy, P; Decolin, D; Nicolas, A; Archimbault, P

1994-12-01

A simple, selective and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the measurement of josamycin residues in four porcine tissues (i.e., muscle, liver, kidney and fat). The sample preparation consisted of a homogenization step in an acetonitrile-10 mmol l-1 phosphate buffer mixture, pH 6.0 (35 + 65), centrifugation and a liquid-liquid extractive clean-up of the resulting supernatant with isooctane. Pre-column derivatization of josamycin was performed using cyclohexa-1,3-dione in ammonium acetate buffer, pH 5.0 (90 degrees C for 2 h). The derivative was chromatographed in an isocratic reversed-phase HPLC system. A LiChrospher RP 18 end-capped (5 microns) column was eluted with an acetonitrile-methanol-10 mmol l-1 phosphate buffer mixture, pH 6.0 (45 + 5 + 50). The capacity factor of the josamycin derivative was 17.5. Detection was achieved using spectrofluorimetry (lambda ex = 375 nm; lambda em = 450 nm). The structure of the derivative was assessed by using mass spectrometry. Full selectivity was obtained in the HPLC system versus other macrolide antibiotics (tylosin, spiramycin and erythromycin), aldehydes (formaldehyde, acetaldehyde and benzaldehyde) and endogenous compounds. Linearity and repeatability were tested. Correlation coefficients, for calibration curves in the range of 0.1-3.2 micrograms g-1, were greater than 0.999 for all tissues and the relative standard deviation (S(r)) was 4.9% (1.6 micrograms g-1; n = 6); recovery was higher than 88%.

An azine based sensor for selective detection of Cu2+ ions and its copper complex for sensing of phosphate ions in physiological conditions and in living cells.

PubMed

Tiwari, Karishma; Kumar, Sumit; Kumar, Vipan; Kaur, Jeevanjot; Arora, Saroj; Mahajan, Rakesh Kumar

2018-02-15

A simple and cost effective unsymmetrical azine based Schiff base, 5-diethylamino-2-[(2-hydroxy-benzylidene)hydrazonomethyl]-phenol (1) was synthesized which selectively detect Cu 2+ ions in the presence of other competitive ions through "naked eye" in physiological conditions (EtOH-buffer (1:1, v/v, HEPES 10mM, pH=7.4)). The presence of Cu 2+ induce color change from light yellow green to yellow with the appearance of a new band at 450nm in UV-Vis spectra of Schiff base 1. The fluorescence of Schiff base 1 (10μM) was quenched completely in the presence of 2.7 equiv. of Cu 2+ ions. Sub-micromolar limit of detection (LOD=3.4×10 -7 M), efficient Stern-Volmer quenching constant (K SV =1.8×10 5 Lmol -1 ) and strong binding constant (log K b =5.92) has been determined with the help of fluorescence titration profile. Further, 1-Cu 2+ complex was employed for the detection of phosphate ions (PO 4 3- , HPO 4 2- and H 2 PO 4 - ) at micromolar concentrations in EtOH-buffer of pH7.4 based on fluorescence recovery due to the binding of Cu 2+ with phosphate ions. Solubility at low concentration in aqueous medium, longer excitation (406nm) and emission wavelength (537nm), and biocompatibility of Schiff base 1 formulates its use in live cell imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Effect of synovial fluid, phosphate-buffered saline solution, and water on the dissolution and corrosion properties of CoCrMo alloys as used in orthopedic implants.

PubMed

Lewis, A C; Kilburn, M R; Papageorgiou, I; Allen, G C; Case, C P

2005-06-15

The corrosion and dissolution of high- and low-carbon CoCrMo alloys, as used in orthopedic joint replacements, were studied by immersing samples in phosphate-buffered saline (PBS), water, and synovial fluid at 37 degrees C for up to 35 days. Bulk properties were analyzed with a fine ion beam microscope. Surface analyses by X-ray photoelectron spectroscopy and Auger electron spectroscopy showed surprisingly that synovial fluid produced a thin oxide/hydroxide layer. Release of ions into solution from the alloy also followed an unexpected pattern where synovial fluid, of all the samples, had the highest Cr concentration but the lowest Co concentration. The presence of carbide inclusions in the alloy did not affect the corrosion or the dissolution mechanisms, although the carbides were a significant feature on the metal surface. Only one mechanism was recognized as controlling the thickness of the oxide/hydroxide interface. The analysis of the dissolved metal showed two mechanisms at work: (1) a protein film caused ligand-induced dissolution, increasing the Cr concentration in synovial fluid, and was explained by the equilibrium constants; (2) corrosion at the interface increased the Co in PBS. The effect of prepassivating the samples (ASTM F-86-01) did not always have the desired effect of reducing dissolution. The release of Cr into PBS increased after prepassivation. The metal-synovial fluid interface did not contain calcium phosphate as a deposit, typically found where samples are exposed to calcium rich bodily fluids. (c) 2005 Wiley Periodicals, Inc.

Mechanisms of Arsenic Hyperaccumulation in Pteris vittata. Uptake Kinetics, Interactions with Phosphate, and Arsenic Speciation1

PubMed Central

Wang, Junru; Zhao, Fang-Jie; Meharg, Andrew A.; Raab, Andrea; Feldmann, Joerg; McGrath, Steve P.

2002-01-01

The mechanisms of arsenic (As) hyperaccumulation in Pteris vittata, the first identified As hyperaccumulator, are unknown. We investigated the interactions of arsenate and phosphate on the uptake and distribution of As and phosphorus (P), and As speciation in P. vittata. In an 18-d hydroponic experiment with varying concentrations of arsenate and phosphate, P. vittata accumulated As in the fronds up to 27,000 mg As kg−1 dry weight, and the frond As to root As concentration ratio varied between 1.3 and 6.7. Increasing phosphate supply decreased As uptake markedly, with the effect being greater on root As concentration than on shoot As concentration. Increasing arsenate supply decreased the P concentration in the roots, but not in the fronds. Presence of phosphate in the uptake solution decreased arsenate influx markedly, whereas P starvation for 8 d increased the maximum net influx by 2.5-fold. The rate of arsenite uptake was 10% of that for arsenate in the absence of phosphate. Neither P starvation nor the presence of phosphate affected arsenite uptake. Within 8 h, 50% to 78% of the As taken up was distributed to the fronds, with a higher translocation efficiency for arsenite than for arsenate. In fronds, 49% to 94% of the As was extracted with a phosphate buffer (pH 5.6). Speciation analysis using high-performance liquid chromatography-inductively coupled plasma mass spectroscopy showed that >85% of the extracted As was in the form of arsenite, and the remaining mostly as arsenate. We conclude that arsenate is taken up by P. vittata via the phosphate transporters, reduced to arsenite, and sequestered in the fronds primarily as As(III). PMID:12428020

PHYSICAL EFFECTS OCCURRING DURING GENERATION AND AMPLIFICATION OF LASER RADIATION: Kinetic model of the active medium of an XeCl laser pumped by an electron beam

NASA Astrophysics Data System (ADS)

Boĭchenko, A. M.; Derzhiev, V. I.; Zhidkov, A. G.; Yakovlenko, Sergei I.

1989-02-01

Kinetic models of active media of an XeCl laser are developed for the case when these media are diluted by various buffer gases (helium, neon, argon) and the laser is pumped by an electron beam. The results of the calculations are in satisfactory agreement with experimental data.

Utilization of Concurrent Buffers to Facilitate Seamless Data Transition in Tactical Cellular Communications

DTIC Science & Technology

2015-09-01

INTENTIONALLY LEFT BLANK xiii LIST OF ACRONYMS AND ABBREVIATIONS 2G 2nd Generation 3G 3rd Generation 3GPP 3rd Generation Partnership Project 4G 4th...System (UMTS) is the standard that governs 3rd Generation ( 3G ) migration of Global Services for Mobile (GSM) networks. It defines packet-based...network may assist or mitigate. 14. SUBJECT TERMS IEEE, 802.21, Media Independent Handover, mobile , communications, cyber, tactical, buffer, cellular

SoyCaP: Soy and Prostate Cancer Prevention

DTIC Science & Technology

2006-11-01

2:16-hydroxyestrone ratio in postmenopausal women depends on equol production status but is not influenced by probiotic consumption. J Nutr 2005 Mar...their habitual diets, and received detailed instructions to exclude soy products in order to minimize isoflavone consumption from other sources...deparaffinized in AmeriClear (Scientific Products , Stockton, CA), rehydrated in graded alcohol, and transferred to phosphate buffered saline (PBS) (pH

Immobilization of folic acid on Eu3+-doped nanoporous silica spheres.

PubMed

Tagaya, Motohiro; Ikoma, Toshiyuki; Yoshioka, Tomohiko; Xu, Zhefeng; Tanaka, Junzo

2011-08-07

Folic acid (FA) was immobilized on Eu(3+)-doped nanoporous silica spheres (Eu:NPSs) through mediation of the 3-aminopropyltriethoxysilane adlayer. The ordered nanopores of Eu:NPS were preserved by the immobilization. The FA-immobilized Eu:NPSs showed the characteristic photoluminescence peak due to interactions between the FA molecules and Eu(3+) ions, and highly dispersed stability in phosphate buffered saline.

Studies on the hemolytic activity of tentacle extracts of jellyfish Rhopilema esculentum Kishinouye: application of orthogonal test.

PubMed

Yu, Huahua; Xing, Ronge; Liu, Song; Li, Cuiping; Guo, Zhanyong; Li, Pengcheng

2007-02-20

The present work is first reporting the hemolytic activity of venom from jellyfish Rhopilema esculentum Kishinouye extracted by different phosphate buffer solutions and incubated at different temperature according to the orthogonal test L6(1) x 3(6). Of the seven controllable independent variables, incubated temperature and phenylmethylsulfonyl fluoride (PMSF) had strongest effect on the hemolytic activity.

An aqueous, organic dye derivatized SnO 2 /TiO 2 core/shell photoanode

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wee, Kyung-Ryang; Sherman, Benjamin D.; Brennaman, M. Kyle

2016-01-01

Visible light driven water splitting in a dye-sensitized photoelectrochemical cell (DSPEC) based on a phosphonic acid-derivatized donor–π–acceptor (D–π–A) organic dye (P–A–π–D) is described with the dye anchored to an FTO|SnO 2/TiO 2core/shell photoanode in a pH 7 phosphate buffer solution.

Korean Hemorrhagic Fever.

DTIC Science & Technology

1981-03-31

secretions, and ectoparasites were prepared in phosphate buffered saline, pH 7.6 containing 0.2% serum bovine albumin(PBS). Penicillin, streptomycin...water source and urine was collected during an interval of 3-5 hours, in sterile bottles containing 10 ml of Hanks balanced solution(BSS) with 1% bovine ...Shope, R. E. and Harrison, A. Physiocochemical and morphological relationships of some arthropod-borne viruses to bluetongue virus - a new taxonomic

Immune Response in Schistosomiasis.

DTIC Science & Technology

1979-08-31

evidence of complications. Nevertheless, it is certain that all these persons were exposed to infection with the parasite . The frequency of exposure to...Cytotoxicity assay. Parasite cycle akid prepacarion of schistoso(Tula A local strain of S. mansoni recovered from patients was maintained by passage in...with schistosoi asis or other helminthic infections. 5 Vol of blood was allowed to sediment with I Vol of 4. :% dextran in phosphate -buffered saline

Spatial and Diel Variability in Photosynthetic and Photoprotective Pigments in Shallow Benthic Communities

DTIC Science & Technology

2002-09-30

phycocyanin analyses, the sediments were extracted repeatedly with a phosphate buffer. An ultrasonicator was used to extract pigments. Concentrations...species composition. While phycoerythrin concentrations varied around 20-fold, phycocyanin varied approximately 70-fold. The highest levels of...chlorophylls a and c, and phycocyanin were found in grapestone sediments and the lowest levels of chlorophylls a and c were found in ooid sands

INACTIVATION OF HEPATITIS A VIRUS AND MODEL VIRUSES IN WATER BY FREE CHLORINE AND MONOCHLORAMINE

EPA Science Inventory

The kinetics and extent of inactivation of hepatitis A virus (HAV) as well as three other viruses, coxsackievirus B5 (CB5) and coliphages MS2 and X174, by 0.5 mg/l free chlorine, pH 6-10, and 10 mg/1 monochloramine, pH8, in 0.01 M phosphate buffer were determined. These results i...

Biomarkers of Alpha Particle Radiation Exposure

DTIC Science & Technology

2014-04-01

Total Protein (TP) g/dL 7.3 7.2 7 7.1 TRIG mg/dL 203 198 203 194 Uric Acid (UA) mg/dL 4 4.1 4.1 4.1 VLDL mg/dL 41 40 41 39 3.1.4 PBMN and WBC...Quantitative Real-Time PCR Radiological Dispersal Device Linear Energy Transfer Deoxyribo Nucleic Acid Fetal Bovine Serum Phosphate Buffered Saline

Enantioselective determination of (R)-zopiclone and (S)-zopiclone (eszopiclone) in human hair by micropulverized extraction and chiral liquid chromatography/high resolution mass spectrometry.

PubMed

Miyaguchi, Hajime; Kuwayama, Kenji

2017-10-13

Zopiclone and its (S)-enantiomer (eszopiclone) are commonly prescribed for insomnia. Despite the high demand for enantioselective differentiation, the chiral analysis of zopiclone in hair has not been reported. In this study, a method for the enantioselective quantification of zopiclone in human hair was developed. The extraction medium and duration were optimized using real eszopiclone-positive hair samples. Specifically, micropulverized extraction with 3.0M ammonium phosphate buffer (pH 8.4) involving salting-out assisted liquid-liquid extraction with acetonitrile was utilized to minimize the degradation of zopiclone and for rapid and facile operation. On the other hand, recovery of the conventional solid-liquid extraction involved overnight soaking in 3.0M ammonium phosphate buffer (pH 8.4) was only 0.58±0.12% of the maximum recovery achieved by the present method due to the decomposition in the phosphate buffer. An excellent chiral separation (Rs=5.0) was achieved using a chiral stationary phase comprising cellulose tris(3,5-dichlorophenylcarbamate) and a volatile mobile phase of 10mM ammonium carbonate (pH 8.0)-acetonitrile (25:75, v/v). Detection was carried out using liquid chromatography/high resolution mass spectrometry (LC/HRMS) with electrospray ionization. A Q Exactive mass spectrometer equipped with a quadrupole-Orbitrap analyzer was used for detection. The concentration of 0.50pg/mg was defined as the lowest limit of quantification using 5mg of hair sample. Using the developed approach, the concentration of eszopiclone in hair after a single 2-mg dose was found to be 441pg/mg, which was higher than all the reported values regarding a single administration of zopiclone. After daily administration of racemic zopiclone (3.75mg/day), the concentrations of (R)-enantiomer and (S)-enantiomer in the black hair were 5.30-8.31ng/mg and 7.96-12.8ng/mg, respectively, and the concentration of the (S)-enantiomer was always higher than that of the (R)-enantiomer due to the enantioselective difference in the pharmacokinetics. Copyright © 2017 Elsevier B.V. All rights reserved.

Intercalation and controlled release of 2,4-dichlorophenoxyacetic acid using rhombohedral [LiAl2(OH)6]Cl·xH2O

NASA Astrophysics Data System (ADS)

Ragavan, Anusha; Khan, Aamir I.; O'Hare, Dermot

2006-05-01

2,4-Dichlorophenoxyacetic acid (2,4-D) has been fully intercalated into the rhombohedral polymorph of [LiAl2(OH)6]Cl·xH2O ([rhom-Li Al] LDH) by an ion exchange method. The controlled release of 2,4-D from the interlamellar spaces of [rhom-Li Al] LDH has been studied in a phosphate buffer, natural rainwater and deionised water. In buffer solution and rainwater, the intercalated herbicide is exchanged for anions in solution. In contrast, in deionised water the herbicide is released as part of the Li+/herbicide ion pair, leading to the formation of Al(OH)3 and the solvated ions.

Enhancing struvite precipitation potential for ammonia nitrogen removal in municipal landfill leachate.

PubMed

Kim, Daekeun; Ryu, Hong-Duck; Kim, Man-Soo; Kim, Jinhyeong; Lee, Sang-Ill

2007-07-19

This study was conducted to improve struvite precipitation for NH4-N removal purpose in landfill leachate. For this purpose, we evaluated the effect of the feeding sequence of precipitating reagents (magnesium, orthophosphate, and buffering reagent) on NH4-N removal by forming struvite deposits. Struvite precipitation effectively proceeded by an addition of excess magnesium and phosphate sources followed by an addition of the buffering reagent, in which condition the local formation of inappropriate deposits or the contamination of the desired struvite was minimized. We also tested the effect of struvite addition as the seeding materials on NH4-N removal. Seed addition would increase the potential for the struvite crystal growth, which enhanced NH4-N removal performance in landfill leachate treatment.

Dual role of starvation signaling in promoting growth and recovery

PubMed Central

Leshkowitz, Dena; Barkai, Naama

2017-01-01

Growing cells are subject to cycles of nutrient depletion and repletion. A shortage of nutrients activates a starvation program that promotes growth in limiting conditions. To examine whether nutrient-deprived cells prepare also for their subsequent recovery, we followed the transcription program activated in budding yeast transferred to low-phosphate media and defined its contribution to cell growth during phosphate limitation and upon recovery. An initial transcription wave was induced by moderate phosphate depletion that did not affect cell growth. A second transcription wave followed when phosphate became growth limiting. The starvation program contributed to growth only in the second, growth-limiting phase. Notably, the early response, activated at moderate depletion, promoted recovery from starvation by increasing phosphate influx upon transfer to rich medium. Our results suggest that cells subject to nutrient depletion prepare not only for growth in the limiting conditions but also for their predicted recovery once nutrients are replenished. PMID:29236696

Comparison of extraction buffers for the detection of fumonisin B(1) in corn by immunoassay and high-performance liquid chromatography.

PubMed

Kulisek, E S; Hazebroek, J P

2000-01-01

The Associatian of Official Analytical Chemists approved method for quantification of fumonisin B(1) (FB(1)) in corn meal or corn-based food products includes extraction into methanol (MeOH)/water (3:1, v/v). Disposal of the extraction medium can pose safety and environmental problems. To secure a rapid and inexpensive screen for FB(1) contamination, a sensitive competitive ELISA using a rabbit polyclonal antibody was developed. This assay was used in a comparative study measuring the extraction efficiency of FB(1) in aqueous or organic solvent buffers using 16 field corn samples. An aqueous phosphate buffer was found to be suitable for extracting FB(1), thus eliminating the need for organic solvents. HPLC and ELISA determinations compared well in fortified samples at known concentrations between 1 and 50 microg/mL of extract. Overestimation at levels >50 microg/mL were common. The characteristics and application of the ELISA for screening purposes are discussed.

Overview on platelet preservation: better controls over storage lesion.

PubMed

Ohto, Hitoshi; Nollet, Kenneth E

2011-06-01

Platelet storage lesion (PSL), correlating with reduced in vivo recovery/survival and hemostatic capacity after transfusion, is characterized essentially by morphological and molecular evidence of platelet activation and energy consumption in the medium. Processes that limit shelf-life are multifactorial, and include both necrosis and apoptosis. PSL is greatly influenced by factors including duration of storage, temperature, ratio of platelet number to media volume, solution composition with respect to energy content and buffering capacity, and gas permeability of the container. Recent progress for slowing PSL has been made with storage media that more effectively fuel ATP production and buffer the inevitable effects of metabolism. Improved oxygen-permeability of containers also helps to maintain aerobic-dominant glycolysis. Patients stand to benefit from platelet products of higher intrinsic quality that store well until the moment of transfusion. Copyright © 2011. Published by Elsevier Ltd.

The effect of processing on veterinary residues in foods.

PubMed

Moats, W A

1999-01-01

Heat stability of antibiotics in foods to cooking has been determined by a variety of methods. These include heating in such liquid media as milk, water, buffers and meat extracts, and in solids such as buffered meat homogenates and various sausages. Inactivation of incurred residues in tissues and eggs was also studied. Time and temperature of heating were more easily controlled in liquid media, but results in actual meat products are more indicative of actual cooking processes. Ordinary cooking procedures for meat, even to "well-done", cannot be relied on to inactivate even the more heat sensitive compounds such as penicillins and tetracyclines. More severe heating as for canning or prolonged cooking with moist heat can inactivate the more heat sensitive compounds. The relevance to food safety is uncertain since the nature of the degradation products is unknown in most cases.

Accumulation of organic compounds leached from plastic materials used in biopharmaceutical process containers.

PubMed

Jenke, Dennis R; Zietlow, David; Garber, Mary Jo; Sadain, Salma; Reiber, Duane; Terbush, William

2007-01-01

Plastic materials are widely used in medical items, such as solution containers, transfusion sets, transfer tubing, and devices. An emerging trend in the biotechnology industry is the utilization of plastic containers to prepare, transport, and store an assortment of solutions including buffers, media, and in-process and finished product. The direct contact of such containers with the product at one or more points in its lifetime raises the possibility that container leachables may accumulate in the finished product. The interaction between several commercially available container materials and numerous model test solutions (representative of buffers and media used in biopharmaceutical applications) was investigated. This paper summarizes the identification of leachables associated with the container materials and documents the levels to which targeted leachables accumulate in the test solutions under defined storage conditions.

An improved method to measure nitrate/nitrite with an NO-selective electrochemical sensor

PubMed Central

Boo, Yong Chool; Tressel, Sarah L.; Jo, Hanjoong

2007-01-01

Nitric oxide produced from nitric oxide synthase(s) is an important cell signaling molecule in physiology and pathophysiology. In the present study, we describe a very sensitive and convenient analytical method to measure NOx (nitrite plus nitrate) in culture media by employing an ultra-sensitive nitric oxide-selective electrochemical sensor which became commercially available recently. An aliquot of conditioned culture media was first treated with nitrate reductase/NADPH/glucose-6-phosphate dehydrogenase/glucose-6-phosphate to convert nitrate to nitrite quantitatively. The nitrite (that is present originally plus the reduced nitrate) was then reduced to equimolar NO in an acidic iodide bath while NO was being detected by the sensor. This analytical method appears to be very useful to assess basal and stimulated NO release from cultured cells. PMID:17056288

Reduction of intergranular exchange coupling and grain size for high Ku CoPt-based granular media: Metal-oxide buffer layer and multiple oxide boundary materials

NASA Astrophysics Data System (ADS)

Tham, Kim Kong; Kushibiki, Ryosuke; Kamada, Tomonari; Hinata, Shintaro; Saito, Shin

2018-05-01

Investigation of magnetic properties and microstructure of granular media with various multiple oxides as the grain boundary material is reported. Saturation magnetization (Ms), uniaxial magnetocrystalline anisotropy (Ku), and magnetic grain diameter (GD) of the granular media show linear correlation with volume weighted average for melting point (Tm) of each oxides (Tmave). Ku of magnetic grains (Kugrain) shows a trade-off relation with GD that it is a big challenge to satisfy both high Kugrain and small GD by only controlling Tmave. To obtain a granular medium with appropriate Kugrain, GD, and low degree of intergranular exchange coupling, the combination of Tmave control of grain boundary material by mixing oxides and employment of a buffer layer are required. Here the degree of intergranular exchange coupling is estimated from the slope of M-H loop at around coercivity (α). By applying this technique, a typical granular medium with Kugrain of 1.0×107 erg/cm3, GD of 5.1 nm, and α of 1.2 is realized.

FACTORS WHICH MODIFY THE EFFECT OF SODIUM AND POTASSIUM ON BACTERIAL CELL MEMBRANES1

PubMed Central

Henneman, Dorothy H.; Umbreit, W. W.

1964-01-01

Henneman, Dorothy H. (Rutgers, The State University, New Brunswick, N.J.), and W. W. Umbreit. Factors which modify the effect of sodium and potassium on bacterial cell membranes. J. Bacteriol. 87:1266–1273. 1964.—Suspensions of Escherichia coli B, when placed in 0.2 to 0.5 m solutions of NaCl, KCl, or LiCl, show an increased turbidity. With NaCl, this increased turbidity is stable with time; with KCl and LiCl, it is gradually lost. The stability to NaCl with time is due to substances removable from the cell by incubation in phosphate buffer; these materials exist in water washings from such phosphate-incubated cells. PMID:14188701

Aerobic Reduction of Arsenate by a Bacterium Isolated From Activated Sludge

NASA Astrophysics Data System (ADS)

Kozai, N.; Ohnuki, T.; Hanada, S.; Nakamura, K.; Francis, A. J.

2006-12-01

Microlunatus phosphovorus strain NM-1 is a polyphosphate-accumulating bacterium isolated from activated sludge. This bacterium takes up a large amount of polyphosphate under aerobic conditions and release phosphate ions by hydrolysis of polyphosphate to orthophosphate under anaerobic conditions to derive energy for taking up substrates. To understand the nature of this strain, especially, influence of potential contaminants in sewage and wastewater on growth, we have been investigating behavior of this bacterium in media containing arsenic. The present paper mainly reports reduction of arsenate by this bacterium under aerobic conditions. The strain NM-1 (JCM 9379) was aerobically cultured at 30 °C in a nutrient medium containing 2.5 g/l peptone, 0.5 g/l glucose, 1.5 g/l yeast extract, and arsenic [Na2HAsO4 (As(V)) or Na3AsO3 (As(III))] at concentrations between 0 and 50 mM. The cells collected from arsenic-free media were dispersed in buffer solutions containing 2mM HEPES, 10mM NaCl, prescribed concentrations of As(V), and 0-0.2 percent glucose. Then, this cell suspension was kept at 20 °C under aerobic or anaerobic conditions. The speciation of arsenic was carried out by ion chromatography and ICP-MS. The growth of the strain under aerobic conditions was enhanced by the addition of As(V) at the concentration between 1 and 10 mM. The maximum optical density of the culture in the medium containing 5mM As(V) was 1.4 times greater than that of the control culture. Below the As(V) concentration of 10mM, most of the As(V) was reduced to As(III). The growth of the strain under anaerobic conditions has not been observed so far. The cells in the buffer solutions reduced As(V) under aerobic condition. The reduction was enhanced by the addition of glucose. However, the cell did not reduce As(V) under anaerobic conditions. The strain NM-1 showed high resistance to As(V) and As(III). The maximum optical density of the culture grown in a medium containing 50 mM As(V) was only 20 percent lower than that of the control culture.

Comparison of charcoal- and starch-based media for testing susceptibilities of Legionella species to macrolides, azalides, and fluoroquinolones.

PubMed Central

Pendland, S L; Martin, S J; Chen, C; Schreckenberger, P C; Danziger, L H

1997-01-01

We compared growth characteristics of 46 Legionella strains grown on buffered charcoal yeast extract alpha (BCYE alpha) agar and buffered starch yeast extract (BSYE) agar and MICs of macrolides, azalides, and fluoroquinolones for these organisms. Growth was poor and not reproducible on BSYE agar. Growth was excellent on BCYE alpha, and MICs were easy to interpret. BCYE alpha is superior to BSYE for testing susceptibilities of Legionella species by agar dilution. PMID:9350781

Interconversion of large packets and small groups of cells of Micrococcus rubens: dependence upon magnesium and phosphate.

PubMed Central

Yamada, M; Koyama, T; Matsuhashi, M

1977-01-01

Micrococcus rubens, a gram-positive occus, usually forms large, cubic packets of more than 500 cells that are regularly arranged in three-dimensional cell groups. In medium with extremely low concentration of Mg2+ and phosphate, in which the cells can only grow on a agar surface, it formed small groups of 2 to 20 cells. Irregularly arraged cell groups of intermediated size were obtained in culture media containing intermediated concentrations of Mg2+ and phosphate. Mutants that formed irregular cell groups of intermediate size under normal culture conditions were also obtained. Images PMID:845123

Cocrystal solubilization in biorelevant media and its prediction from drug solubilization

PubMed Central

Lipert, Maya P.; Roy, Lilly; Childs, Scott L.

2015-01-01

This work examines cocrystal solubility in biorelevant media, (FeSSIF, fed state simulated intestinal fluid), and develops a theoretical framework that allows for the simple and quantitative prediction of cocrystal solubilization from drug solubilization. The solubilities of four hydrophobic drugs and seven cocrystals containing these drugs were measured in FeSSIF and in acetate buffer at pH 5.00. In all cases, the cocrystal solubility (Scocrystal) was higher than the drug solubility (Sdrug) in both buffer and FeSSIF; however, the solubilization ratio of drug, SRdrug = (SFeSSIF/Sbuffer)drug, was not the same as the solubilization ratio of cocrystal, SRcocrystal = (SFeSSIF/Sbuffer)cocrystal, meaning drug and cocrystal were not solubilized to the same extent in FeSSIF. This highlights the potential risk of anticipating cocrystal behavior in biorelevant media based on solubility studies in water. Predictions of SRcocrystal from simple equations based only on SRdrug were in excellent agreement with measured values. For 1:1 cocrystals, the cocrystal solubilization ratio can be obtained from the square root of the drug solubilization ratio. For 2:1 cocrystals, SRcocrystal is found from (SRdrug)2/3. The findings in FeSSIF can be generalized to describe cocrystal behavior in other systems involving preferential solubilization of a drug such as surfactants, lipids, and other drug solubilizing media. PMID:26390213

In vitro germination of zygotic embryos of hybrid BRS Manicoré (E. guineensis X E. oleifera).

PubMed

Bonetti, Keila A P; Quoirin, Marguerite; Quisen, Regina C; Lima, Suelen C S

2016-01-01

The interspecific oil palm hybrid BRS Manicoré (E. guineensis x E. oleifera) has superior agronomic characteristics. However, the germination rate is low (30%) and the process is slow when the seeds are sown in a conventional form. The purpose of this study was to optimize the in vitro germination of zygotic embryos of this hybrid comparing seed lots. The viability of zygotic embryos was evaluated by the tetrazolium test (0.075%) for 4 h. The embryos were cultured on MS and Y3 culture media, with and without the addition of NaH2PO4, as well as on MS, MS1/2 and N6 medium. In MS medium containing NaH2PO4, the germination rate was increased from 40 to 70% in comparison with the medium without sodium phosphate. The comparison between the culture media MS, MS 1/2, N6 and Y3 showed that 75% of zygotic embryos cultured in the Y3 medium formed whole plants (with roots and shoots defined), a higher percentage than embryos cultured on MS, MS 1/2 and N6 media (46, 35 and 17% respectively). In the same Y3 culture medium, the embryos were larger (36% ≥ 2 cm and 30% ≥ 5 cm) than in the other media. Results obtained by the tetrazolium test were similar to those of germination, showing the effect of the genotype of each seed lot. For the germination and development of plantlets it is essential to add NaH2PO4 to a culture medium containing no phosphate or with a low phosphate concentration.

Phosphate sorption and desorption on pyrite in primitive aqueous scenarios: relevance of acidic --> alkaline transitions.

PubMed

de Souza-Barros, Fernando; Braz-Levigard, Raphael; Ching-San, Yonder; Monte, Marisa M B; Bonapace, José A P; Montezano, Viviane; Vieyra, Adalberto

2007-02-01

Phosphate (P(i)) sorption assays onto pyrite in media simulating primeval aquatic scenarios affected by hydrothermal emissions, reveal that acidic conditions favour P(i) sorption whereas mild alkaline media--as well as those simulating sulfur oxidation to SO(2-) (4)--revert this capture process. Several mechanisms relevant to P(i) availability in prebiotic eras are implicated in the modulation of these processes. Those favouring sorption are: (a) hydrophobic coating of molecules, such as acetate that could be formed in the vicinity of hydrothermal vents; (b) water and Mg(2+) bridging in the interface mineral-aqueous media; (c) surface charge neutralization by monovalent cations (Na+ and K+). The increase of both the medium pH and the SO(2-) (4) trapping by the mineral interface would provoke the release of sorbed P(i) due to charge polarization. Moreover it is shown that P(i) self-modulates its sorption, a mechanism that depends on the abundance of SO(2-) (4) in the interface. The relevance of the proposed mechanisms of P(i) capture, release and trapping arises from the need of abundant presence of this molecule for primitive phosphorylations, since--similarly to contemporary aqueous media--inorganic phosphate concentrations in primitive seas should have been low. It is proposed that the presence of sulphide minerals with high affinity to P(i) could have trapped this molecule in an efficient manner, allowing its concentration in specific niches. In these niches, the conditions studied in the present work would have been relevant for its availability in soluble form, specially in primitive insulated systems with pH gradients across the wall.

Cooperativity between various types of polar solute-solvent interactions in aqueous media.

PubMed

Madeira, Pedro P; Bessa, Ana; Loureiro, Joana A; Álvares-Ribeiro, Luís; Rodrigues, Alírio E; Zaslavsky, Boris Y

2015-08-21

Partition coefficients of seven low molecular weight compounds were measured in multiple aqueous two-phase systems (ATPSs) formed by pairs of different polymers. The ionic composition of each ATPS was varied to include 0.01M sodium phosphate buffer (NaPB), pH 7.4 and 0.1M Na2SO4, 0.15M NaCl, and 0.15M NaClO4 all in 0.01M NaPB, pH 7.4. The differences between the solvent features of the coexisting phases in all the ATPSs were estimated from partitioning of a homologous series of dinitrophenylated-amino acids and by the solvatochromic method. The solute-specific coefficients for the compounds examined were determined by the multiple linear regression analysis using the modified linear solvation energy relationship equation. It is established that the solute specific coefficients characterizing different types of the solute-water interactions (dipole-dipole, dipole-ion, and H-bonding) for a given solute change in the presence of different salt additives in the solute specific manner. It is also found that these characteristics are linearly interrelated. It is suggested that there is a cooperativity between various types of solute-water interactions governed by the solute structure. Copyright © 2015 Elsevier B.V. All rights reserved.

Role of calcium in phosphoinositide metabolism and inhibition of norepinephrine transport into synaptic vesicles by amphetamine analogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Knepper, S.M.

1985-01-01

Norepinephrine-(NE) and calcium ionophore A23187-stimulated phosphoinositide (PIn) metabolism in rat brain slices was studied under varying calcium conditions. Tissue was labelled with /sup 3/H-myo-inositol and /sup 3/H-inositol phosphates (IPn), products of PIn metabolism were measured. In the absence of media calcium the response to NE was decreased while that to A23187 was little affected A23187 can release calcium from intracellular stores. Basal and stimulated accumulation of /sup 3/H-IPn was reversibly antagonized with EGTA by addition of calcium. Using calcium buffers, approximately 10/sup -7/ M free calcium was required to support hydrolysis. Free intracellular calcium is maintained at approximately this level.more » Thus calcium is required for PIn hydrolysis but appears to play a permissive role, basal levels being sufficient to support metabolism. Conformationally-defined (rigid) and -restricted (semi-rigid) analogs of the most stable conformations of amphetamine, antiperiplanar (exo) and gauche (endo), were utilized to probe the conformational requirements of vesicular NE transport. Analogs tested were 2-aminotetralin (2AT), 3-methyltetrahydroisoquinoline, anti- and syn-9-aminobenzobicyclo(2.2.1)heptene, and endo and exo conformers of 2-aminobenzobicyclo(2.2.1)heptene and 2-aminobenzobicyclo(2.2.2)octene.« less

Micro-Electromechanical Affinity Sensor for the Monitoring of Glucose in Bioprocess Media

PubMed Central

Theuer, Lorenz; Lehmann, Micha; Junne, Stefan; Neubauer, Peter; Birkholz, Mario

2017-01-01

An affinity-viscometry-based micro-sensor probe for continuous glucose monitoring was investigated with respect to its suitability for bioprocesses. The sensor operates with glucose and dextran competing as binding partner for concanavalin A, while the viscosity of the assay scales with glucose concentration. Changes in viscosity are determined with a micro-electromechanical system (MEMS) in the measurement cavity of the sensor probe. The study aimed to elucidate the interactions between the assay and a typical phosphate buffered bacterial cultivation medium. It turned out that contact with the medium resulted in a significant long-lasting drift of the assay’s viscosity at zero glucose concentration. Adding glucose to the medium lowers the drift by a factor of eight. The cglc values measured off-line with the glucose sensor for monitoring of a bacterial cultivation were similar to the measurements with an enzymatic assay with a difference of less than ±0.15 g·L−1. We propose that lectin agglomeration, the electro-viscous effect, and constitutional changes of concanavalin A due to exchanges of the incorporated metal ions may account for the observed viscosity increase. The study has demonstrated the potential of the MEMS sensor to determine sensitive viscosity changes within very small sample volumes, which could be of interest for various biotechnological applications. PMID:28594350

Secretion of Ipa proteins by Shigella flexneri: inducer molecules and kinetics of activation.

PubMed Central

Bahrani, F K; Sansonetti, P J; Parsot, C

1997-01-01

The type III Mxi-Spa secretion machinery of Shigella flexneri is responsible for secretion of Ipa proteins, which are involved in the entry of bacteria into epithelial cells. Ipa proteins accumulate within bacteria growing in laboratory media, and their secretion is activated upon contact of bacteria with eukaryotic cells. In this study, we have identified a group of chemical compounds, including Congo red, Evans blue, and direct orange, which are able to induce secretion of Ipa proteins by bacteria suspended in phosphate-buffered saline. Parameters of kinetics of activation of Ipa secretion by Congo red were determined by measuring by enzyme-linked immunosorbent assay the amount of IpaC secreted and by investigating the increase in susceptibility of Ipa proteins to proteinase K degradation. Ipa secretion occurred at 37 degrees C, was obtained with 5 to 10 microM Congo red, and was complete within 30 min. In addition, activation of Ipa secretion by Congo red was observed with bacteria harvested throughout the exponential phase of growth but not with bacteria in the stationary phase. The interactions of Congo red and Congo red-related compounds with the Mxi-Spa secretion apparatus might be specific hydrophobic interactions similar to those involved in binding of Congo red to amyloid proteins. PMID:9316999

Electrospraying technique for the fabrication of metronidazole contained PLGA particles and their release profile.

PubMed

Prabhakaran, Molamma P; Zamani, Maedeh; Felice, Betiana; Ramakrishna, Seeram

2015-11-01

Advanced engineering of materials for the development of drug delivery devices provides scope for novel and versatile strategies for treatment of various diseases. 'Electrospraying' was used to prepare PLGA microparticles and further encapsulate the drug, metronidazole (Met) within the particles to function as a drug delivery system. Two different solvents were utilized for the preparation of drug loaded PLGA particles, whereby the polymeric solution in dichloromethane (DCM) produced particles of bigger sizes than using trifluoroethanol (TFE). Scanning electron microscopy showed the spherical morphology of the particles, with sizes of 3946±407nm and 1774±167nm, respectively for PLGA-Met(DCM) and PLGA-Met(TFE). The FTIR spectroscopy proved the incorporation of metronidazole in the polymer, but without any specific drug-polymer interaction. The release of the drug from the particles was studied in phosphate buffered saline, where a sustained drug release was obtained for at least 41days. Cytotoxicity evaluation of the drug extract using mesenchymal stem cells (MSCs) showed not hindering the proliferation of MSCs, and the cell phenotype was retained after incubation in the drug containing media. Electrospraying is suggested as a cost-effective and single step process for the preparation of polymeric microparticles for prolonged and controlled release of drug. Copyright © 2015 Elsevier B.V. All rights reserved.

Application of hanging drop technique for stem cell differentiation and cytotoxicity studies.

PubMed

Banerjee, Meenal; Bhonde, Ramesh R

2006-05-01

The aim of our study is to explore the possibility of using an ancient method of culture technique- the hanging drop technique for stem cell differentiation and cytotoxicity testing. We demonstrate here a variety of novel applications of this age old technique not only to harness the differentiation potential of stem cells into specific lineages but also for cytotoxicity studies. Here we have prepared hanging drop cultures by placing 20 microl micro-drops of nutrient media and 10% Fetal Calf Serum (FCS) containing cells of interest on the lids of 60 mm dishes. Bottom plates of the dishes were filled with sterile Phosphate Buffer Saline (PBS) to avoid desiccation of samples. Lids were then placed on the bottom plates to achieve hanging drop cultures. We utilized this technique for cultivation of ciliated epithelia to study cytotoxicity and differentiation of bone marrow stromal cells. Most importantly the modified culture technique presented here is simple, economical and cost effective in terms of the time taken and the reagents required and are amenable to goal specific modification such as cytotoxicity testing. It is advantageous over the existing system in terms of retention of viability and functionality for longer duration and for providing three dimensional growth micro-environment making it useful for organotypic cultures and in vivo simulation.

Transport behavior of hairless mouse skin during constant current DC iontophoresis, part 2: iontophoresis of nonionic molecules with cotransport of polystyrene sulfonate oligomers.

PubMed

Liddell, Mark R; Li, S Kevin; Higuchi, William I

2011-07-01

The purpose of this study was to characterize changes that occur in the iontophoretic transport of nonionic probe permeants in hairless mouse skin epidermal membrane from the anode to cathode when polystyrene sulfonate (PSS) oligomers are cotransported from the cathode to anode. The experiments were conducted with trace levels of the nonionic probe permeants: urea, mannitol, and raffinose. In order to systematically assess changes that occur as a result of having PSS in the cathodal chamber, the steady-state transport parameters of the membrane and the experimental permeability coefficients of the probe permeants were determined and compared with results obtained from earlier baseline experiments where both the cathodal and anodal chamber media were phosphate buffered saline. In addition, the physicochemical properties of the PSS solutions were determined including the solution viscosity and conductance as well as the mobilities of individual PSS oligomers. The effective pore radii of the transport pathways were calculated using a theoretical expression based on simultaneous diffusion and electroosmosis. Compared with the baseline results, the calculated radii were found to have increased up to around twofold and the iontophoretic fluxes of the probe permeants increased by as much sixfold. Copyright © 2011 Wiley-Liss, Inc. and the American Pharmacists Association

Cholesterol-modified poly(lactide-co-glycolide) nanoparticles for tumor-targeted drug delivery.

PubMed

Lee, Jeong-Jun; Lee, Song Yi; Park, Ju-Hwan; Kim, Dae-Duk; Cho, Hyun-Jong

2016-07-25

Poly(lactide-co-glycolide)-cholesterol (PLGA-C)-based nanoparticles (NPs) were developed for the tumor-targeted delivery of curcumin (CUR). PLGA-C/CUR NPs with ∼200nm mean diameter, narrow size distribution, and neutral zeta potential were fabricated by a modified emulsification-solvent evaporation method. The existence of cholesterol moiety in PLGA-C copolymer was confirmed by proton nuclear magnetic resonance ((1)H NMR) analysis. In vitro stability of developed NPs after 24h incubation was confirmed in phosphate buffered saline (PBS) and serum media. Sustained (∼6days) and pH-responsive drug release profiles from PLGA-C NPs were presented. Blank PLGA and PLGA-C NPs exhibited a negligible cytotoxicity in Hep-2 (human laryngeal carcinoma) cells in the tested concentration range. According to the results of flow cytometry and confocal laser scanning microscopy (CLSM) studies, PLGA-C NPs presented an improved cellular accumulation efficiency, compared to PLGA NPs, in Hep-2 cells. Enhanced in vivo tumor targetability of PLGA-C NPs, compared to PLGA NPs, in Hep-2 tumor-xenografted mouse model was also verified by a real-time near-infrared fluorescence (NIRF) imaging study. Developed PLGA-C NPs may be a candidate of efficient and biocompatible nanosystems for tumor-targeted drug delivery and cancer imaging. Copyright © 2016 Elsevier B.V. All rights reserved.

Transport features of nano-hydroxylapatite (n-HA) embedded silicone rubber (SR) systems: influence of SR/n-HA interaction, degree of reinforcement and morphology.

PubMed

M, Bindu; G, Unnikrishnan

2017-09-27

We report the transport characteristics of silicone rubber/nano-hydroxylapatite (SR/n-HA) systems at room temperature with reference to the effects of n-HA loading, morphology and penetrant nature, using toluene, xylene, ethyl acetate and butyl acetate in the liquid phase and methanol, ethanol, 1-propanol, 2-propanol and butanol in the vapour phase as probe molecules. The interaction between the n-HA particles and SR matrix has been confirmed by FTIR analysis. As the n-HA content in the SR matrix increased, the penetrant uptake has been found to decrease. The observations have been correlated with the density and void content of the systems. Scanning electron microscopy images have been found to be complementary to the observed transport features. The reinforcement effect of n-HA particles on the SR matrix has been verified by Kraus equation. Molecular mass between the cross links has been observed to decrease with an increase in n-HA loading. The results have been compared with affine, phantom network, parallel, series and Maxwell models. The transport data have been complemented by observations on biological fluid uptake with urea, d-glucose, KI, saline water, phosphate buffer and artificial urine as the media.

Imaging and cell targeting characteristics of magnetic nanoparticles modified by a functionalizable zwitterionic polymer with adhesive 3,4-dihydroxyphenyl-l-alanine linkages.

PubMed

Zhang, Lei; Xue, Hong; Gao, Changlu; Carr, Louisa; Wang, Jinnan; Chu, Baocheng; Jiang, Shaoyi

2010-09-01

Multifunctional magnetic nanoparticles (MNPs) modified by a zwitterionic polymer (pCBMA-DOPA(2)) containing one poly(carboxybetaine methacrylate) (pCBMA) chain and two 3,4-dihydroxyphenyl-L-alanine (DOPA) residue groups were developed. Results showed that MNPs modified by pCBMA were not only stable in complex media, but also provided abundant functional groups for ligand immobilization. The pCBMA-DOPA(2) MNPs had a hydrodynamic particle size of about 130 nm, a strong saturation magnetization of 110.2 emu/g Fe and a high transverse relaxivity of 428 mM(-1)s(-1). Long-term stability in phosphate-buffered saline (PBS) and 10% NaCl solution was achieved for over six months. Compared to MNPs coated with dextran, pCBMA-DOPA(2) MNPs presented better stability in 100% human blood serum at 37 degrees C. Macrophage cell uptake studies revealed that the uptake ratio of pCBMA-DOPA(2) MNPs was much lower than that of dextran MNPs. Furthermore, quantitative analysis results showed that after pCBMA-DOPA(2) MNPs were conjugated with a targeting RGD peptide, uptake by human umbilical vein endothelial cell (HUVEC) was notably increased, which was further visualized by magnetic resonance imaging (MRI). Copyright (c) 2010 Elsevier Ltd. All rights reserved.