Comparison of four selective media for the isolation of Burkholderia mallei and Burkholderia pseudomallei

Currently there are no commercially available selective media indicated for the isolation of Burkholderia mallei and Burkholderia pseudomallei. Ashdown's agar, a custom selective medium for isolation of B. pseudomallei, is well described in the literature but unavailable commercially. Three commercially available media, Burkholderia cepacia selective agar (BCSA), oxidative-fermentative-polymyxin B-bacitracin-lactose (OFPBL) agar, and Pseudomonas cepacia (PC) agar are recommended for isolation of B. cepacia from respiratory secretions of cystic fibrosis patients. We evaluated the sensitivity and selectivity of these four media using 20 B. mallei, 20 B. pseudomallei, 20 Burkholderia spp., and 15 diagnostically challenging organisms. Ashdown's agar was the most sensitive medium for the isolation of B. pseudomallei, but it was unable to support growth of B. mallei. Pseudomonas cepacia agar was highly sensitive and selective for both organisms. In non-endemic areas, we suggest the use of the commercially available PC agar for the isolation of B. mallei and B. pseudomallei.

Variations in the composition of gelling agents affect morphophysiological and molecular responses to deficiencies of phosphate and other nutrients

Low inorganic phosphate (Pi) availability triggers an array of spatiotemporal adaptive responses in Arabidopsis (Arabidopsis thaliana). There are several reports on the effects of Pi deprivation on the root system that have been attributed to different growth conditions and/or inherent genetic variability. Here we show that the gelling agents, largely treated as inert components, significantly affect morphophysiological and molecular responses of the seedlings to deficiencies of Pi and other nutrients. Inductively coupled plasma-mass spectroscopy analysis revealed variable levels of elemental contaminants not only in different types of agar but also in different batches of the same agar. Fluctuating levels of phosphorus (P) in different agar types affected the growth of the seedlings under Pi-deprivation condition. Since P interacts with other elements such as iron, potassium, and sulfur, contaminating effects of these elements in different agars were also evident in the Pi-deficiency-induced morphological and molecular responses. P by itself acted as a contaminant when studying the responses of Arabidopsis to micronutrient (iron and zinc) deficiencies. Together, these results highlighted the likelihood of erroneous interpretations that could be easily drawn from nutrition studies when different agars have been used. As an alternative, we demonstrate the efficacy of a sterile and contamination-free hydroponic system for dissecting morphophysiological and molecular responses of Arabidopsis to different nutrient deficiencies.

In vitro antioxidant activities of low-molecular-weight polysaccharides with various functional groups

The objectives of this study were to evaluate the effect of different functional groups of sulfate, amine, and hydroxyl and/or their ionized groups on in vitro antioxidant capacities of low-molecular-weight polysaccharides (LMPS) prepared from agar (LMAG), chitosan (LMCH), and starch (LMST), respectively, and to elucidate their structure-activity relationship. Ascorbic acid and ethylenediaminetetraacetic acid (EDTA) were used as positive controls. The in vitro antioxidant capacities of LMAG and LMCH were higher than that of LMST in the DPPH radical, superoxide radical, hydrogen peroxide, and nitric oxide radical scavenging and ferrous metal-chelating capacities. The different scavenging capacities may be due to the combined effects of the different sizes of the electron-cloud density and the different accessibility between free radical and LMPS, which, in turn, depends upon the different hydrophobicities of the constituent sugars.

The effects of soil and Trifolium repens (white clover) on the fate of estrogen

In this study, we investigated the behavior of estrogens in the rhizosphere of white clover (Trifolium repens, clover hereafter) with two different pot tests, using soil and agar as growth media. In a pot test using agar spiked with estrogen, the estrogen concentration in the agar with clover decreased to non-detectable levels within one month, while in the agar without clover, 60% of initially added estrogen remained after one month. The half-lives of estrone (E1) and 17beta -estradiol (E2) in the agar with clover were 2.4-3.8 and 13.2 d, respectively. The dissipation of E1 followed first-order rate law, while that of E2 fitted a zero-order reaction, indicating that they had different mechanisms of dissipation from agar. In the soil pot test, the behavior of E1 and E2 was not influenced by clover. An initial rapid decrease in the amount of estrogen extracted by methanol/acetic acid was followed by persistence for 1-3 months, regardless of presence of clover. Moreover, in three weeks E1 and E2 were only partly degraded by microbes extracted from the soil used in the pot test. In this study, abiotic degradation of estrogens and sorption of estrogen to soil, rather than the effects of soil microbes and clover, contributed to the initial rapid dissipation of estrogens in the soil. However, the results of the agar pot test suggested that vegetation such as clover may significantly contribute to removal of estrogens when estrogens in aqueous phase are discharged with surface runoff and preferential flow after heavy rain in agricultural fields, or when present in soils with low estrogen sorptivity.

Agar from Gracilaria gracilis (Gracilariales, Rhodophyta) of the Patagonic coast of Argentina--content, structure and physical properties

Milled summer thalli of Gracilaria gracilis from Argentina were sequentially extracted with water at room temperature (RTW1-3), 70 degrees C (W701-3) and 90 degrees C (W901-2). Both W701 and W901 consisted of high molecular weight polysaccharides (ca. 540,000Da), but polydispersity was higher for the major product W701 (yield, 72% of the recovered). Structural analyzes by methylation and (13)C NMR spectroscopy revealed that W701 was mainly agarose. Alkaline treatment, together with structural analyzes, indicated a negligible proportion of precursor l-galactose 6-sulfate residues in this product, while they were clearly detected in the (13)C NMR spectra of RTW2-3. The presence of floridean starch in W901 had an antagonistic effect on its gel strength, which resulted nearly three times lower than that of fraction W701. Ultrastructural observation by transmission electron microscopy showed that, after extraction with hot water, a partial loss of cell wall stratification and disorganization of the cuticle had occurred. Final cellular debris exhibited swelling in the microfibrillar component. After this first thorough study of the chemical composition and physical properties of the products of G. gracilis from Bahía Bustamante we conclude that a good quality agarose is obtained in high yield after extraction with water at 70 degrees C without the requirement of alkaline pretreatment, which usually produces degradation of the polysaccharide.

Determination of mercury in water and fish samples by cold vapor atomic absorption spectrometry after solid phase extraction on agar modified with 2-mercaptobenzimidazole

A novel solid phase extraction method for the determination of mercury has been developed. The Hg(II) ions were retained on a mini-column packed with agar powder modified with 2-mercaptobenzimidazole at a flow rate of 6 mL min(-1). The retained Hg(II) ions were eluted with 3 mol L(-1) solution of HCl and measured by cold vapor atomic absorption spectrometry (CV-AAS). The effect of different variables such as pH, sample flow rate, amounts of 2-mercaptobenzimidazole loaded on agar and SnCl(2) concentration was investigated and optimum conditions were established. The calibration curve was linear in the range of 0.040-2.40 ng mL(-1) with r=0.9994 (n=8). The limit of detection based on three times the standard deviation (3S(b)) (n=10) obtained under optimum conditions was 0.02 ng mL(-1). The relative standard deviation (R.S.D.) for the determination of 0.4 and 2.0 ng mL(-1) of Hg(II) was 2.6 and 1.9% (n=8), respectively. The method was successfully applied to determine Hg(II) in water, wastewater and fish samples.

The effect of lactic acid bacteria isolates on the urinary tract pathogens to infants in vitro

Urinary tract infections are common clinical problems in children, even though lots of treatment strategies have been tried. Many studies of the application of probiotics for urinary tract infection in female adults exist, but there is a lack of studies in children. The aims of this study were to screen probiotic strains for inhibiting the uropathogens in vitro, to find candidates for in vivo study. Nine strains of E. coli were isolated from children with urinary tract infection and six uropathogens were obtained from Korean Collection for Type Cultures and American Type Culture Collection. Also 135 lactic acid bacteria (LAB) strains were isolated from healthy children, and were identified through physiologic, biochemical methods, 16S rDNA PCR, and data analysis. And with agar disk diffusion assay technique the antimicrobial activities of these LAB strains against those uropathogens were examined. Three strains of separated LAB strains demonstrated major antimicrobial activity against all the uropathogens. In the agar disk diffusion assay technique, antimicrobial activities increased most in the 4th day culture broth with separated Lactobacillus. In summary, some LAB can be used as candidates to develop the probiotic microorganisms that inhibit uropathogens in children, and are expected to be applied to treatment and prevention of pediatric urinary tract infection.

Improvement of the matching speed of AIMS for development of an automatic totally tuning system for hyperthermia treatment using a resonant cavity applicator

In this paper, we discuss the improvement of the speed of AIMS (Automatic Impedance Matching System) to automatically make impedance matching for a re-entrant resonant cavity applicator for non-invasive deep brain tumors hyperthermia treatments. We have already discussed the effectiveness of the heating method using the AIMS, with experiments of heating agar phantoms. However, the operating time of AIMS was about 30 minutes. To develop the ATT System (Automatic Totally Tuning System) including the automatic frequency tuning system, we must improve this problem. Because, when using the ATTS, the AIMS is used repeatedly to find the resonant frequency. In order to improve the speed of impedance matching, we developed the new automatic impedance matching system program (AIMS2). In AIMS, the stepping motors were connected to the impedance matching unit's dials. These dials were turned to reduce the reflected power. AIMS consists of two phases: all range searching and detailed searching. We focused on the three factors affecting the operating speed and improved them. The first factor is the interval put between the turning of the motors and AD converter. The second factor is how the steps of the motor when operating all range searching. The third factor is the starting position of the motor when detail searching. We developed the simple ATT System (ATT-beta) based on the AIMS2. To evaluate the developed AIMS2 and ATT- beta, experiments with an agar phantom were performed. From these results, we found that the operating time of the AIMS2 is about 4 minutes, which was approximately 12% of AIMS. From ATT-beta results, it was shown that it is possible to tune frequency and automatically match impedance with the program based on the AIMS2.

Quantification of SPIO nanoparticles using phase gradient mapping

A new method is developed to quantify the concentration of super-paramagnetic iron oxide (SPIO) contrast agent using magnetic resonance imaging (MRI). The proposed method utilizes a positive contrast method, known as phase gradient mapping (PGM), to find the gradient of the field map. Then the concentration is calculated by fitting the gradient of the field map to the gradient of an ideal geometric model. The proposed method was compared to relaxivity-based SPIO quantification method and was applied to calculate the concentration of SPIO contrast agent for MRI experiments performed on a phantom with known concentrations. The results obtained from the proposed method accord well with the true concentrations.

An explanatory model to validate the way water activity rules periodic terrace generation in Proteus mirabilis swarm

This paper explains the biophysical principles which, according to us, govern the Proteus mirabilis swarm phenomenon. Then, this explanation is translated into a mathematical model, essentially based on partial differential equations. This model is then implemented using numerical methods of the finite volume type in order to make simulations. The simulations show most of the characteristics which are observed in situ and in particular the terrace generation.

Spectral filtering for improved pulsed photothermal temperature profiling in agar tissue phantoms

We present a systematic experimental comparison of pulsed photothermal temperature profiling utilizing the customary spectral band of the InSb radiation detector (lambda=3.0 to 5.6 microm) and a narrowed acquisition band (4.5 to 5.6 microm). We use custom tissue phantoms composed of agar gel layers separated by thin absorbing layers. The laser-induced temperature profiles are reconstructed within the customary monochromatic approximation, using a custom minimization algorithm. In a detailed numerical simulation of the experimental procedure, we consider several acquisition spectral bands with the lower wavelength limit varied between 3.0 and 5.0 microm (imitating application of different long-pass filters). The simulated PPTR signals contain noise with amplitude and spectral characteristics consistent with our experimental system. Both experimental and numerical results indicate that spectral filtering reduces reconstruction error and broadening of temperature peaks, especially for shallower and more complex absorbing structures. For the simulated PPTR system and watery tissues, numerical results indicate an optimal lower wavelength limit of 3.8 to 4.2 microm.

Stability of agar in the seaweed Gracilaria eucheumatoides (Gracilariales, Rhodophyta) during postharvest storage

The status of the cell-wall polysaccharide of the red seaweed, Gracilaria eucheumatoides upon postharvest storage was assessed in this study. The yield, chemical composition, physical and textural properties of alkali-treated agar extract was determined at different time intervals within 31 months of storage at dried state after harvest. Minimal fluctuation in agar yield was observed, ranging from 22.9% to 29.0%. The gel strength of agar extracts averaged 318gcm(-2) until the third month of storage but decreased considerably thereafter. The relative viscosity and molecular weight of the extracts varied inversely with storage time. Results indicated that both physical and textural parameters of agar generally decreased with storage time, likely due to depolymerization as indicated by decrease in molecular weight. Agar extracted from seaweeds up to 3 months of storage could be considered to exhibit gel quality suitable for food applications. Prolonged storage of the seaweed harvest is not recommended.

[Susceptibility testing of Mycobacterium tuberculosis isolates to primary antituberculous drugs on chocolate agar: a preliminary study]

The aim of this study was to evaluate the use of chocolate agar as an alternative medium instead of Middlebrook 7H10 agar, for the susceptibility testing of Mycobacterium tuberculosis strains against isoniazid (INH), rifampicin (RIF), streptomycin (STR) and ethambutol (ETM). The susceptibility results obtained by chocolate agar were compared with the results of BACTEC 460 TB (Becton Dickinson, Sparks, MD, USA) system which was accepted as the reference method. A total of 25 M. tuberculosis clinical isolates were included to the study and susceptibility testing was performed on malachite green added-chocolate agar with some modifications of proportion method recommended by NCCLS. In our study when comparing the results obtained by chocolate agar with the results of BACTEC 460 TB system, the concordance rates for INH, STR, RIF and ETM were found as 88%, 88%, 84% and 72%, respectively. The specificity, sensitivity, positive and negative predictive values of susceptibility testing on chocolate agar have been detected as 82.3%, 100%, 72.7% and 100% for INH; 78.5%, 100%, 78.5% and 100% for RIF; 83.3%, 84.2%, 94.1% and 62.5% for STR; 25%, 94.1%, 72.7% and 66.6% for ETM, respectively. The results of the susceptibility testing performed on chocolate agar were obtained on the 21st day of incubation for all isolates. In conclusion, the data from our study suggested that chocolate agar can be used as an alternative medium for the susceptibility testing of M. tuberculosis, however, further studies with more isolates are needed for the standardisation of the method.

Enhancement of heavy metal accumulation by tissue specific co-expression of iaaM and ACC deaminase genes in plants

1-Aminocyclopropane deaminase (ACC) and tryptophan monooxygenase are two enzymes involved in plant senescence-inhibiting and growth-promoting regulation, respectively. In this study, two binary vectors were constructed in which the Agrobacterium iaaM gene was under the transcriptional control of a xylem-specific glycine-rich protein promoter alone, or co-expressed with the bacterial ACC deaminase gene, which was driven by the constitutive CaMV 35S promoter. Transgenic petunia shoots co-expressing both genes were able to root on medium supplemented with 7.5 mg l(-1) CoCl2. When T1 transgenic tobacco plants were grown in sand supplemented with Cu2+ and Co2+, tissue specific co-expression of both iaaM and ACC deaminase genes showed faster growth with larger biomass with a more extensive root system, and accumulated a greater amount of heavy metals than the empty vector control plants. When T1 transgenic tobacco plants were grown in soil watered with different concentrations of CuSO4, xylem specific expression of the iaaM gene caused the accumulation of more Cu2+ than the empty vector control at lower CuSO4 concentrations, but showed severe toxic symptoms at concentration of 100 mg l(-1) CuSO4. T1 transgenic plants co-expressing both genes accumulated more heavy metals into the plant shoots and can tolerate CuSO4 at 150 mg l(-1). In addition, plants co-expressing these two genes can grow well in a complex contaminated soil containing both inorganic and organic pollutants, while the growth of the control plants was greatly inhibited.

Pump-probe imaging of nanosecond laser-induced bubbles in agar gel

In this paper we show results of Nd:YAG laser-induced bubbles formed in a one millimeter thick agar gel slab. The nine nanosecond duration pulse with a wave length of 532 nm was tightly focused inside the bulk of the gel sample. We present for the first time a pump-probe laser-flash shadowgraphy system that uses two electronically delayed Nd:YAG lasers to image the the bubble formation and shock wave fronts with nanosecond temporal resolution and up to nine seconds of temporal range. The shock waves generated by the laser are shown to begin at an earlier times within the laser pulse as the pulse energy increases. The shock wave velocity is used to infer a shocked to unshocked material pressure difference of up to 500 MPa. The bubble created settles to a quasi-stable size that has a linear relation to the maximum bubble size. The energy stored in the bubble is shown to increase nonlinearly with applied laser energy, and corresponds in form to the energy transmission in the agar gel. We show that the interaction is highly nonlinear, and most likely is plasma-mediated.

Injectability evaluation of tricalcium phosphate bone cement

Calcium phosphate cements are biomaterials made from a mixture of calcium phosphate powder in aqueous solutions that forms a paste that reacts at the body temperature and hardens as a result of precipitation reactions. These cements are commonly used in dentistry and orthopedic bone filling surgeries, which require extremely invasive procedures. The challenge consists in formulating an injectable paste by additives incorporation. In this work, three different additives (carboxymethylcellulose, agar polymer and sodium alginate) were incorporated to tricalcium phosphate, in concentrations of 0.4, 0.8, 1.6, 3.2 and 6.4 wt.%. Injectability was evaluated through a new method developed for this purpose. Results showed that it was possible to obtain injectable compositions of alpha-tricalcium phosphate cement. It was verified that the injectability depends on the rheological behavior of the pastes and injection time. In this study, pastes with viscosity suitable for good homogenization and injection were obtained.

Callogenic studies of Achyranthes aspera leaf explant at different hormonal combinations

With the objective to promote in vitro callus induction, leaf segments of Achyranthes aspera were inoculated on basal MS medium supplemented with 3.0% sucrose and 0.8% agar with different concentrations of 2,4-D alone and in combination with NAA, BAP, IAA, IBA and Zeatin. The explants were maintained in growth room at 25 +/- 1 degrees C and 16 h light cycle. The best callus induction was obtained with 2,4-D (1.0 and 2.0 mg L(-l)) in combination with NAA (0.5 mg L(-1)). Callus induction and good texture from leaf explant was also observed at 2,4-D with BAP. On these combinations morphologically, light green, soft, compact and non-embryogenic callus (Type III callus) was observed. While morphology of callus and callogenic response was poor at 2,4-D alone or in combination with other hormones at different concentrations.

Enumeration of lactobacilli in the fecal flora of infant using two different modified de-Man Rogosa Sharpe media under aerobic and anaerobic incubation

Regarding the importance of the presence of intestinal lactobacilli and their population in infants, four different treatments were evaluated for Lactobacillus isolation efficiency via reduction in the growth of other groups of bacteria capable of growing on de-Man Rogosa Sharpe (MRS) medium from fecal samples of 11 Iranian infants. MRS-Vancomycin (1 mg L(-l)) was used as a base medium and application of lactic acid and aerobic incubation of inoculated plates were performed as selective factors. Each fecal sample was cultivated as duplicate on to the base medium with or without lactic acid to reduce the pH to 5.4 +/- 0.2. Half of the plates were incubated aerobically and the rest of them incubated under 10% CO2 concentration. Total count and Lactobacillus count of all samples were recorded according to the age differences of infants. The counts of false positive colonies were recorded with respect to their cell morphology and gram reaction in all treatments. Anaerobic incubation of lactic acid modified MRS-Vancomycin gave the most Lactobacillus percentage coverage, about 93% among the Lactobacillus positive samples. Using this treatment, the median Lactobacillus count yielded 8.29 log10 cfu g(-1) in the younger and 5.70 log10 cfu g(-1) in the elder group. It could be concluded that lactic acid might be a proper pH reducing agent when enumeration of lactobacilli from fecal samples is of interest.

Partial purification of cytolytic venom proteins from the box jellyfish, Chironex fleckeri

Venom proteins from the nematocysts of Chironex fleckeri were fractionated by size-exclusion and cation-exchange chromatography. Using sheep erythrocyte haemolysis as an indicator of cytolytic activity, two major cytolysins, with native molecular masses of approximately 370 and 145kDa, and one minor cytolysin ( approximately 70kDa) were isolated. SDS-PAGE and western blot protein profiles revealed that the 370kDa haemolysin is composed of CfTX-1 and CfTX-2 subunits ( approximately 43 and 45kDa, respectively); the most abundant proteins found in C. fleckeri nematocyst extracts. The 145kDa haemolysin predominately contains two other major proteins ( approximately 39 and 41kDa), which are not antigenic towards commercially available box jellyfish antivenom or rabbit polyclonal antibodies raised against whole C. fleckeri nematocyst extracts or CfTX-1 and -2. The kinetics of CfTX-1 and -2 haemolytic activities are temperature dependent and characterised by a pre-lytic lag phase ( approximately 6-7min) prior to initiation of haemolysis. Significant amino acid sequence homology between the CfTX proteins and other box jellyfish toxins suggest that CfTX-1 and -2 may also be lethal and dermonecrotic. Therefore, further in vivo and in vitro studies are required to investigate the potential roles of CfTX-1 and -2 in the lethal effects of C. fleckeri venom.

Acoustoelasticity in soft solids: assessment of the nonlinear shear modulus with the acoustic radiation force

The assessment of viscoelastic properties of soft tissues is enjoying a growing interest in the field of medical imaging as pathologies are often correlated with a local change of stiffness. To date, advanced techniques in that field have been concentrating on the estimation of the second order elastic modulus (mu). In this paper, the nonlinear behavior of quasi-incompressible soft solids is investigated using the supersonic shear imaging technique based on the remote generation of polarized plane shear waves in tissues induced by the acoustic radiation force. Applying a theoretical approach of the strain energy in soft solid [Hamilton et al., J. Acoust. Soc. Am. 116, 41-44 (2004)], it is shown that the well-known acoustoelasticity experiment allowing the recovery of higher order elastic moduli can be greatly simplified. Experimentally, it requires measurements of the local speed of polarized plane shear waves in a statically and uniaxially stressed isotropic medium. These shear wave speed estimates are obtained by imaging the shear wave propagation in soft media with an ultrafast echographic scanner. In this situation, the uniaxial static stress induces anisotropy due to the nonlinear effects and results in a change of shear wave speed. Then the third order elastic modulus (A) is measured in agar-gelatin-based phantoms and polyvinyl alcohol based phantoms.

Isolation of lipase producing Bacillus sp. from olive mill wastewater and improving its enzyme activity

The bacteria that could grow on media containing olive mill wastewater (OMW) were isolated and their lipase production capacities were investigated. The strain possessing the highest lipase activity among 17 strains grown on tributyrin agar medium was identified as Bacillus sp. The effect of initial pH on the lipase activity was investigated in tributyrin medium and pH 6 was found to be the optimal. The liquid medium composition was improved by replacing tributyrin with various carbon sources. Among the media containing different compositions of triolein, trimyristin, trilaurin, tricaprin, tricaprylin, tributyrin, triacetin, Tween 80, OMW, glucose, and whey; the medium contained 20% whey +1% triolein was found to give the highest lipase activity. Cultivation of Bacillus sp. in the optimal medium at pH 6 and 30 degrees C for 64h resulted in the extracellular and intracellular lipase activities of 15 and 168U/ml, respectively.

Chromium and zinc uptake by algae Gelidium and agar extraction algal waste: kinetics and equilibrium

Biosorption of chromium and zinc ions by an industrial algal waste, from agar extraction industry has been studied in a batch system. This biosorbent was compared with the algae Gelidium itself, which is the raw material for agar extraction, and the industrial waste immobilized with polyacrylonitrile (composite material). Langmuir and Langmuir-Freundlich equilibrium models describe well the equilibrium data. The parameters of Langmuir equilibrium model at pH 5.3 and 20 degrees C were for the algae, q(L)=18 mg Cr(III)g(-1) and 13 mgZn(II)g(-1), K(L) = 0.021l mg(-1)Cr(III) and 0.026l mg(-1) Zn(II); for the algal waste, q(L)=12 mgCr(III)g(-1) and 7mgZn(II)g(-1), K(L)=0.033lmg(-1) Cr(III) and 0.042l mg(-1) Zn(II); for the composite material, q(L) = 9 mgCr(III)g(-1) and 6 mgZn(II)g(-1), K(L)=0.032l mg(-1)Cr(III) and 0.034l mg(-1)Zn(II). The biosorbents exhibited a higher preference for Cr(III) ions and algae Gelidium is the best one. The pseudo-first-order Lagergren and pseudo-second-order models fitted well the kinetic data for the two metal ions. Kinetic constants and equilibrium uptake concentrations given by the pseudo-second-order model for an initial Cr(III) and Zn(II) concentration of approximately 100 mgl(-1), at pH 5.3 and 20 degrees C were k(2,ads)=0.04 g mg(-1)Cr(III)min(-1) and 0.07 g mg(-1)Zn(II)min(-1), q(eq)=11.9 mgCr(III)g(-1) and 9.5 mgZn(II)g(-1) for algae; k(2,ads)=0.17 g mg(-1)Cr(III)min(-1) and 0.19 g mg(-1)Zn(II)min(-1), q(eq)=8.3 mgCr(III)g(-1) and 5.6 mgZn(II)g(-1) for algal waste; k(2,ads)=0.01 g mg(-1)Cr(III)min(-1) and 0.18 g mg(-1)Zn(II)min(-1), q(eq)=8.0 mgCr(III)g(-1) and 4.4 mgZn(II)g(-1) for composite material. Biosorption was modelled using a batch adsorber mass transfer kinetic model, which successfully predicts Cr(III) and Zn(II) concentration profiles. The calculated average homogeneous diffusivities, D(h), were 4.2 x 10(-8), 8.3 x 10(-8) and 1.4 x 10(-8)cm(2)s(-1) for Cr(III) and 4.8 x 10(-8), 9.7 x 10(-8) and 6.2 x 10(-8)cm(2)s(-1) for Zn(II), respectively, for Gelidium, algal waste and composite material. The algal waste has the lower intraparticle resistance.

Inhibition of Salmonella enterica serotype Enteritidis on agar and raw chicken by carvacrol vapour

Carvacrol is known to inhibit a number of food borne pathogens. The activity of carvacrol vapour was evaluated against S. enterica serotype Enteritidis on tryptone soya agar and on pieces of raw chicken. On agar, the size of the inhibition zone increased with decreasing volume of agar, increasing vapour exposure period, increasing temperature, increasing volume of carvacrol used and with decreasing bacterial density. Inhibition was equally effective under aerobic and anaerobic conditions. On chicken pieces (10 x 10 x 5 mm, UV-sterilized and inoculated with approx. 5 x 10(3) cfu) carvacrol vapour significantly reduced viable numbers of salmonellae at 4, 20 and 37 degrees C and all viable cells were eliminated by a minimum of 3 h at 37 degrees C (p<0.05). A minimum concentration of 20% carvacrol v/v in ethanol was required to achieve a significant reduction and from 40% v/v no viable cells were recovered (p<0.05). In conclusion, carvacrol vapour is effective at inhibiting the growth of S. enterica serotype Enteritidis on agar and at inhibiting and eliminating these bacteria on the surface of raw chicken.

Targeting thioredoxin reductase 1 reduction in cancer cells inhibits self-sufficient growth and DNA replication

Thioredoxin reductase 1 (TR1) is a major redox regulator in mammalian cells. As an important antioxidant selenoprotein, TR1 is thought to participate in cancer prevention, but is also known to be over-expressed in many cancer cells. Numerous cancer drugs inhibit TR1, and this protein has been proposed as a target for cancer therapy. We previously reported that reduction of TR1 levels in cancer cells reversed many malignant characteristics suggesting that deficiency in TR1 function is antitumorigenic. The molecular basis for TR1's role in cancer development, however, is not understood. Herein, we found that, among selenoproteins, TR1 is uniquely overexpressed in cancer cells and its knockdown in a mouse cancer cell line driven by oncogenic k-ras resulted in morphological changes characteristic of parental (normal) cells, without significant effect on cell growth under normal growth conditions. When grown in serum-deficient medium, TR1 deficient cancer cells lose self-sufficiency of growth, manifest a defective progression in their S phase and a decreased expression of DNA polymerase α, an enzyme important in DNA replication. These observations provide evidence that TR1 is critical for self-sufficiency in growth signals of malignant cells, that TR1 acts largely as a pro-cancer protein and it is indeed a primary target in cancer therapy.