Predilution On-Line Hemodiafiltration Improves Albumin Redox in Maintenance Hemodialysis Patients.

BACKGROUND/AIM: In this study, we compared the dialysis efficiency, oxidative stress, and nutritional conditions between predilution on-line hemodiafiltration (pre-OL-HDF) and conventional hemodialysis (HD) using a super-flux dialyzer (CHD). METHOD: This was a crossover study of 38 maintenance HD patients. All patients were treated with CHD for the first 4 months (1st CHD period), then were switched to pre-OL-HDF for 4 months (pre-OL-HDF period), and were returned to CHD for the next 4 months (2nd CHD period). RESULTS: We found no significant difference in the removal ratio of small uremic substances or the indices of inflammation or nutritional states between the pre-OL-HDF and CHD periods. However, we found higher removal of ß2 micro-globulin in the pre-OL-HDF period, and the human mercapto-albumin (Alb)/human serum Alb ratio was significantly higher in the pre-OL-HDF period. CONCLUSION: Treatment with pre-OL-HDF enabled enhanced removal of middle molecule uremic toxins and better Alb redox than did CHD.

A near-infrared fluorescent sensor with large Stokes shift for rapid and highly selective detection of thiophenols in water samples and living cells.

The development of simple methods with high sensitivity and selectivity to differentiate toxic aromatic thiols (thiophenols) from aliphatic thiols (cysteine, homocysteine, and glutathione) and hydrogen sulfide (H2S) is of great significance. Herein, we report on the fabrication of a novel near-infrared (NIR) fluorescent sensor for rapid and highly selective detection of thiophenols through the photoinduced electron transfer (PET) mechanism. In the presence of the thiophenols, an obvious enhancement of NIR fluorescence at 658 nm could be visualized with the aid of nucleophilic aromatic substitution (SNAr) reaction. The sensor displays large Stokes shift (~ 227 nm), fast response time (< 30 s), high sensitivity (~ 8.3 nM), and good biocompatibility. Moreover, the as-prepared sensor possesses an excellent anti-interference feature even when other possible interferents exist (aliphatic thiols and H2S) and has been successfully utilized for thiophenol detection in both water samples and living cells. Graphical abstract Illustration of the sensor for thiophenol imaging in living cells.

Low-cost colorimetric assay of biothiols based on the photochemical reduction of silver halides and consumer electronic imaging devices.

This work describes a new approach for the determination of free biothiols in biological fluids that exploits some of the basic principles of early photographic chemistry - that was based on silver-halide recording materials - and uses broadly-available imaging devices (i.e. flatbed scanners) as detectors. Specifically, the proposed approach relies on the ability of biothiols to bind to silver ions and dissociate the silver halide crystals thus changing the photosensitivity of silver halide crystal suspension. The changes induced by biothiols on the light intensity transmitted through the silver halide suspension, after photochemical reduction, were measured with a simplified photometric approach that employs a flatbed scanner operating in transmittance mode. The overall analytical procedure for the determination of biothiols was easily executable, fast and could be applied with inexpensive and commercially available materials and reagents. What is more, physiologically relevant biothiol levels could be inspected even by the unattended eye. The developed assay was successfully applied to the determination of biothiols in urine and blood plasma samples with detection limits as low as 10µM, satisfactory recoveries (92-97%), good reproducibility (6.7-8.8%) and high selectivity against other major components of biological fluids. The utility of the method to the determination of reduced/oxidized thiol ratio's as well as its application under natural light illumination, without external energy sources, was also demonstrated and is discussed with regard to point-of need applications in facility-limited settings.

Biomarkers of oxidative damage in bacteria for the assessment of sanitation efficacy in lettuce wash water.

In the fresh produce industry, validation of sanitation efficacy is critical to prevent cross-contamination of produce. The current validation approaches are either based on time-consuming plate counting assays or indirect measurements of chemical properties of wash water. In the study, the focus was to identify biomarkers that can provide direct assessment of oxidative damage in bacteria upon exposure to sanitizers in the presence of fresh produce and correlation of these oxidative biomarkers with logarithmic inactivation of bacteria. Two endogenous bacterial biomarkers, protein carbonylation and thiol oxidation, were evaluated for assessing oxidative damage in Escherichia coli O157:H7 and Listeria innocua during sanitation of pre-cut lettuce leaves with NaOCl or H2O2. Results show that NaOCl treatment was more effective than H2O2 for oxidation of both the intracellular thiols and protein carbonylation in the selected strains. Statistical analysis of the measurements illustrates that oxidation of the intracellular thiol induced by NaOCl or H2O2 was correlated with logarithmic reduction of E. coli O157:H7 and L. innocua. In contrast, changes in the protein carbonylation content were not correlated with reduction in bacterial cell viability. In summary, these results provide a novel approach to validate sanitation efficacy for the fresh produce industry.

An objective assessment of halitosis in children with adenoid vegetation during pre- and post-operative period.

OBJECTIVES: Although most specialists in otorhinolaryngology and pediatrics find halitosis to be a common problem in children with adenoid hypertrophy, there are no objective data on this topic in the literature. Whether adenoid hypertrophy is a risk factor for halitosis or whether halitosis is a sign of adenoid hypertrophy remains unclear. Thus, the aim of this study was to investigate whether children diagnosed with adenoid hypertrophy have a higher probability of halitosis than do children in the normal population and whether adenoidectomy can decrease oral malodor. METHODS: Forty children with adenoid hypertrophy and 40 healthy subjects aged 5-15 years were included in the study. The children with adenoid hypertrophy underwent adenoidectomy operations and were followed for 3 months. We measured volatile sulfur compounds (VSCs), hydrogen sulfide (H2S), methyl mercaptan (CH3SH), and dimethyl sulfide (CH3)2S using an objective method, a portable gas chromatograph (OralChroma; AbiMedical, Osaka, Japan). RESULTS: The mean CH3SH and (CH3)2S levels were significantly different (p < 0.05) between the adenoid hypertrophy group and the controls. The H2S, CH3SH, and (CH3)2S levels in the third postoperative month were significantly lower (p < 0.05) than those in the preoperative period, and there was no significant difference postoperatively between the patients with adenoid hypertrophy and controls. There was a positive correlation between age and VSC levels, and CH3SH levels were significantly higher in patients with ventilation tube insertion, rather than just adenoidectomy. CONCLUSIONS: There was a statistically significant association between halitosis and adenoid hypertrophy, and a significant improvement in halitosis was obtained following adenoidectomy. The present study provides an association between halitosis and adenoid hypertrophy. If there is no other oral pathology causing halitosis, halitosis can be a sign of adenoid hypertrophy in children.

Simultaneous assessment of endogenous thiol compounds by LC-MS/MS.

Biological thiol compounds are very important molecules that participate in various physiological events. Alteration in levels of endogenous thiols has been suggested as a biomarker of early stage of pathological changes. We reported a chemical derivatization- and LC-MS/MS-based approach to simultaneously determine thiol compounds including glutathione (GSH), cysteine (Cys), N-acetyl cysteine (NAC), homocysteine (Hcy), and cysteinylglycine (CysGly) in biological samples. Thiol-containing samples were derivatized with monobromobimane (mBrB) at room temperature, followed by LC-MS/MS analysis. Assessment of the analytes with baseline separation was completed within 10min, using a gradient elution on a C18 reversed-phase column. Excellent linearity was observed for all analytes over their concentration ranges of 1-400µM. The lowest limits of detection (S/N=3) in a range from 0.31fmol (for NAC) to 4.98fmol (for CysGly) were achieved. The results indicate that this approach was sensitive, selective, and well suited for high-throughput quantitative determination of the biological thiols.

Quantification of Polyfunctional Thiols in Wine by HS-SPME-GC-MS Following Extractive Alkylation.

Analyses of key odorous polyfunctional volatile thiols in wines (3-mercaptohexanol (3-MH), 3-mercaptohexylacetate (3-MHA), and 4-mercapto-4-methyl-2-pentanone (4-MMP)) are challenging due to their high reactivity and ultra-trace concentrations, especially when using conventional gas-chromatography electron impact mass spectrometry (GC-EI-MS). We describe a method in which thiols are converted to pentafluorobenzyl (PFB) derivatives by extractive alkylation and the organic layer is evaporated prior to headspace solid phase microextraction (HS-SPME) and GC-EI-MS analysis. Optimal parameters were determined by response surface area modeling. The addition of NaCl solution to the dried SPME vials prior to extraction resulted in up to less than fivefold improvement in detection limits. Using 40 mL wine samples, limits of detection for 4-MMP, 3-MH, and 3-MHA were 0.9 ng/L, 1 ng/L, and 17 ng/L, respectively. Good recovery (90%-109%) and precision (5%-11% RSD) were achieved in wine matrices. The new method was used to survey polyfunctional thiol concentrations in 61 commercial California and New York State wines produced from V. vinifera (Riesling, Gewürztraminer, Cabernet Sauvignon, Sauvignon blanc and non-varietal rosé wines), V. labruscana (Niagara), and Vitis spp. (Cayuga White). Mean 4-MMP concentrations in New York Niagara (17 ng/L) were not significantly different from concentrations in Sauvignon blanc, but were significantly higher than 4-MMP in other varietal wines.

Effects of high hydrostatic pressure on physicochemical and functional properties of walnut (Juglans regia L.) protein isolate.

BACKGROUND: Walnut (Juglans regia L.) is a good source of protein that has potential application in new product formation and fortification. The main objectives of this study were to investigate the effects of high hydrostatic pressure (HHP) treatment (300-600 MPa 20 min) on physicochemical and functional properties of walnut protein isolate (WPI) using various analytical techniques at room temperature. RESULTS: The results showed significant modification of solubility, free sulfhydryl content and surface hydrophobicity with increased levels of HHP treatment, indicating partial denaturation and aggregation of proteins. Differential scanning calorimetry and fluorescence spectrum analyses demonstrated that HHP treatment resulted in gradual unfolding of protein structure. Emulsifying activity index was significantly (P < 0.05) increased after HHP treatment at 400 MPa, but significantly decreased (P < 0.05) relative to the untreated WPI with further increase in pressure. HHP treatment at 300-600 MPa significantly decreased emulsion stability index. Additionally, HHP-treated walnut proteins showed better foaming properties and in vitro digestibility. CONCLUSION: These results suggest that HHP treatment could be applied to modify the properties of walnut proteins by appropriate of pressure levels, which will help in using walnut protein as a potential food ingredient.

Electrochemical gas sensors based on paper-supported room-temperature ionic liquids for improved analysis of acid vapours.

A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon which three electrodes are screen printed by carbon ink profiting from a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs and of their easy immobilization into a porous and inexpensive supporting material such as paper. The performance of this device, used as a wall-jet amperometric detector for flow injection analyses of headspace samples in equilibrium with aqueous solutions at controlled concentrations, was evaluated for phenol and 1-butanethiol vapours which were adopted as model acid gaseous analytes. The results obtained showed that the quite high potentials required for the detection of these analytes are lowered significantly, thanks to the addition of the basic acetate RTIL. In such a way, overlap with the medium discharge is avoided, and the possible adverse effect of interfering species is minimised. The sensor performance was quite satisfactory (detection limits, ca. 0.3 µM; dynamic range, ca. 1-200 µM, both referred to solution concentrations; correlation coefficients in the range 0.993-0.997; repeatability, ± 6% RSD; long-term stability, 9%); thus suggesting the possible use of this device for manifold applications.

Pilot evaluation of a novel test strip for the assessment of dissolved thiol levels, as an indicator of canine gingival health and periodontal status.

This study evaluated a novel test strip designed to assess thiol levels as they relate to gingival/periodontal health in dogs. The simple to use strip (similar in form to a pH test strip) provides a colorimetric signal which estimates the level of thiols dissolved in oral fluid. Among several oral sites tested (left and right lingual vestibules, lower buccal vestibule, and upper buccal gingival margin), fluid from the maxillary gingival margin gave results with the best dynamic range, and its thiol levels correlated well with several oral health parameters (Pearson coefficients between 0.55 and 0.84; P < 0.001), especially those relating directly to the gingiva. The strip, which can be used on animals which are awake, may be useful as a quick, objective assessment of periodontal health, potentially enhancing compliance for thorough examinations, and promoting earlier and better-sustained treatment programs.

Évaluation pilote d'un nouveau bâtonnet diagnostique pour l'évaluation des taux de thiol dissous comme indicateur de la santé gingivale canine et de la situation parodontale. Cette étude a évalué un nouveau bâtonnet diagnostique conçu pour évaluer les taux de thiol tels qu'ils se rapportent à la santé gingivale et parodontale des chiens. Le bâtonnet facile à utiliser (de forme semblable à un bâtonnet diagnostique de pH) fournit un signal colorimétrique qui estime le taux de thiols dissous dans le liquide buccal. Parmi plusieurs sites buccaux testés (vestibules linguaux gauche et droit, vestibule buccal inférieur et bord marginal de la gencive buccale supérieure), le liquide du bord marginal de la gencive maxillaire a donné les résultats avec le meilleur écart dynamique et ses taux de thiol correspondaient bien à plusieurs paramètres de la santé buccale (coefficients de Pearson entre 0,55 et 0,84; P < 0,001), particulièrement ceux se rapportant directement à la gencive. Le bâtonnet, qui peut être utilisé sur les animaux lorsqu'ils sont éveillés, pourra être utile comme évaluation objective rapide de la santé parodontale, ce qui rehaussera potentiellement l'observance pour des examens complets et fera la promotion de programmes de traitement mieux soutenus qui sont administrés plus tôt.(Traduit par Isabelle Vallières).

Assessment of the aroma impact of major odor-active thiols in pan-roasted white sesame seeds by calculation of odor activity values.

Eleven odor-active thiols, namely, 2-methyl-1-propene-1-thiol, (Z)-3-methyl-1-butene-1-thiol, (E)-3-methyl-1-butene-1-thiol, (Z)-2-methyl-1-butene-1-thiol, (E)-2-methyl-1-butene-1-thiol, 2-methyl-3-furanthiol, 3-mercapto-2-pentanone, 2-mercapto-3-pentanone, 4-mercapto-3-hexanone, 3-mercapto-3-methylbutyl formate, and 2-methyl-3-thiophenethiol, recently identified in an extract prepared from white sesame seeds, were quantitated in sesame using stable isotope dilution analyses. For that purpose, the following deuterium-labeled compounds were synthesized and used as internal standards in the quantitation assays: [2H6]-2-methyl-1-propene-1-thiol, [2H3]-(E)- and [2H3]-(Z)-2-methyl-1-butene-1-thiol, [2H3]-2-methyl-3-furanthiol, [2H2]-3-mercapto-2-pentanone, [2H3]-4-mercapto-3-hexanone, [2H6]-3-mercapto-3-methylbutyl formate, and [2H3]-2-methyl-3-thiophenethiol. On the basis of the results obtained, odor activity values (OAVs) were calculated as ratio of the concentration and odor threshold of the individual compounds in cooking oil. According to their high OAVs, particularly the 3-methyl-1-butene-1-thiols (OAV: 2400) and the 2-methyl-1-butene-1-thiols (OAV: 960) were identified as the most odor-active compounds in pan-roasted white sesame seeds. These compounds were therefore suggested to be mainly responsible for the characteristic but rather unstable sulfury aroma of freshly pan-roasted white sesame seeds.

Gelation properties of spent duck meat surimi-like material produced using acid-alkaline solubilization methods.

The gelation properties of spent duck meat surimi-like material produced using acid solubilization (ACS) or alkaline solubilization (ALS) were studied and compared with conventionally processed (CON) surimi-like material. The ACS process yielded the highest protein recovery (P < 0.05). The ALS process generated the highest lipid reduction, and the CON process yielded the lowest reduction (P < 0.05). Surimi-like material produced by the CON process had the highest gel strength, salt extractable protein (SEP), and water holding capacity (WHC), followed by materials produced via the ALS and ACS processes and untreated duck meat (P < 0.05). The material produced by the CON process also had the highest cohesiveness, hardness, and gumminess values and the lowest springiness value. Material produced by the ACS and ALS processes had higher whiteness values than untreated duck meat gels and gels produced by the CON method (P < 0.05). Surimi-like material produced using the ACS and CON processes had significantly higher myoglobin removal (P < 0.05) than that produced by the ALS method and untreated duck meat. Among all surimi-like materials, the highest Ca(2+)-ATPase activity was found in conventionally produced gels (P < 0.05). This suggests that protein oxidation was induced by acid-alkaline solubilization. The gels produced by ALS had a significantly lower (P < 0.05) total SH content than the other samples. This result showed that the acid-alkaline solubilization clearly improved gelation and color properties of spent duck and possibly applied for other high fat raw material.

Is oxidative stress a physiological cost of reproduction? An experimental test in house mice.

Investment in reproduction is costly and frequently decreases survival or future reproductive success. However, the proximate underlying causes for this are largely unknown. Oxidative stress has been suggested as a cost of reproduction and several studies have demonstrated changes in antioxidants with reproductive investment. Here, we test whether oxidative stress is a consequence of reproduction in female house mice (Mus musculus domesticus), which have extremely high energetic demands during reproduction, particularly through lactation. Assessing oxidative damage after a long period of reproductive investment, there was no evidence of increased oxidative stress, even when females were required to defend their breeding territory. Instead, in the liver, markers of oxidative damage (malonaldehyde, protein thiols and the proportion of glutathione in the oxidized form) indicated lower oxidative stress in reproducing females when compared with non-reproductive controls. Even during peak lactation, none of the markers of oxidative damage indicated higher oxidative stress than among non-reproductive females, although a positive correlation between protein oxidation and litter mass suggested that oxidative stress may increase with fecundity. Our results indicate that changes in redox status occur during reproduction in house mice, but suggest that females use mechanisms to cope with the consequences of increased energetic demands and limit oxidative stress.

Automated tagging of pharmaceutically active thiols under flow conditions using monobromobimane.

The thiol-specific derivatization reagent monobromobimane (MBB) is applied--for the first time--under flow conditions. Sequential injection analysis allows the handling of precise volumes of the reagent in the micro-liter range. The effect of the main chemical and instrumental variables was investigated using captopril (CAP), N-acetylcysteine (NAC) and penicillamine (PEN) as representative pharmaceutically active thiols. Previously reported hydrolysis of MBB due to interaction with nucleophilic components of the buffers was avoided kinetically under flow conditions. The proposed analytical scheme is suitable for the fluorimetric determination of thiols at a sampling rate of 36 h(-1).

Development of square wave voltammetry method for the assessment of organophosphorus compound impact on the cholinesterase of Pheretima with 2,6-dichloroindophenol as a redox indicator.

A square wave voltammetry method was developed for the assessment of organophosphorus (OPs) compound impact on the cholinesterase of Pheretima with 2,6-dichloroindophenol (2,6-DCIP) as a redox indicator. The substrate of acetylthiocholine is hydrolysed by the cholinesterase (ChE) from soil animal pheretima, and the produced thiocholine reacts with the 2,6-DCIP to give obvious shift of electrochemical signal. The inhibition of ChE was assessed by measuring the enzyme activity before and after incubating with parathion-methyl. The reduction peak current of 2,6-DCIP decreases with the time of enzymatical reaction. The ChE loses almost 32.74% activity after 10 min incubation with 1ng mL(-1) paraoxon and 54.62% with 10 microg mL(-1) paraoxon, while the activity that corresponds to 100 microg mL(-1) paraoxon was nearly completely inhibited. This method can be employed to assess the inhibition of ChE and investigate OPs impact on environmental animals.

Rapid assessment of the latent hazard posed by dissolved mercaptans within aqueous effluent.

The presence of mercaptans (RSH) can usually be detected by their inherent noxious odour but there is a need to quantify the concentration within effluent and hence allow an assessment of the latent hazard to be made prior to disposal. The versatility of using naphthoquinone as a rapid derivatising agent through which to trap such species has been evaluated. The quinone moiety provides a label that can be quantified using colorimetric, electrochemical and chromatographic means and offers a significant advantage over conventional thiol labelling agents. The analytical characteristics of each approach have been investigated and the selectivity, sensitivity and applicability of the reaction system critically assessed for a range of model compounds. The naphthoquinone system has a detection limit in the low micromolar range with little interference from other components common to discharge water with 96% recovery of mercaptopropionate. The reaction to sulfide (HS-) has also been assessed and a disparity in response between the detection methods observed and a possible reaction pathway outlined.

The assessment of methyl mercaptan, an important clinical marker for the diagnosis of oral malodor.

OBJECTIVE: This study aimed to determine the clinical assessment of volatile sulfur compound (VSCs) for the evaluation of noticeable oral malodor using gas chromatography (GC). METHODS: The oral malodor of 127 adult patients was investigated using the organoleptic test and GC, and the relation between the organoleptic evaluation and VSCs were analyzed. RESULTS: The optimum cut-off values of CH3SH, H2S and total VSC (CH3SH + H2S) to discriminate between the patients with and without noticeable oral malodor were obtained from ROC curves, and determined to be 0.44, 1.10 and 2.20 ng/10 ml, respectively. The logistic regression was analyzed for estimation of the association between an organoleptic evaluation greater than a slight level and the groups with CH3SH, H2S or total VSC with concentrations above the optimum cut-off value. Only CH3SH showed an independent association with noticeable oral malodor. CONCLUSIONS: It was evident that CH3SH was a more useful marker for the evaluation of oral malodor than H2S. Moreover, it appears CH3SH is the predominant causative factor of noticeable oral malodor.

Correlation between measurements using a new halitosis monitor and organoleptic assessment.

Halitosis is known as unpleasant oral odor and is a health concern among the general public. Previously, we reported on a new portable monitor with a zinc-oxide, thin-film, semiconductor sensor which demonstrated simplicity of handling, high reproducibility and correspondence for organoleptic assessment. The results suggested its usefulness for the diagnosis of halitosis. Using the monitor, oral air samples of 94 subjects were measured in a field survey, and the values were compared with the organoleptic rates of corresponding samples assessed by two judges. A highly significant correlation (r = 0.824, P < 0.01) was demonstrated between the measures obtained by the two methods. The results suggest that the monitor is useful for not only a clinical study but also a field study of halitosis.

Assessment of sulfhydryl group in individual rat lens protein subunits during galactose cataract development.

A specific reagent DACM [N-(7-Dimethylamino-4-methyl-3-coumarinyl)maleimide] is used to study the -SH groups in lens proteins of normal and galactose cataractous rats. DACM when reacts readily with -SH groups form strong fluorescent adducts. The two -dimensional electrophoresis with DACM pre-labeled proteins is a simple and sensitive method for detecting -SH groups of protein subunit. In the present study, based on IEF/SDS-PAGE electrophoretically characterized soluble crystallins, describes specific changes in -SH groups of protein subunit during the development of galactose cataract. The contents of -SH groups of crystallins are progressively decreased in cataractous (5+) lens, the reduction of -SH content in alpha- and beta- crystallin protein subunits of the normal and cataractous lens proteins is also noticeable.

Assessment of lysyl oxidase variants by urea gel electrophoresis: evidence against disulfide isomers as bases of the enzyme heterogeneity.

Methods for the copurification and rapid assessment of the protein profiles corresponding to the multiple variants of bovine aortic lysyl oxidase are described. The individual variants do not resolve from each other by electrophoresis in sodium dodecyl sulfate but are resolved by gel electrophoresis in 8 M urea, thus providing a new method for their detection independent of enzyme assay. Alkylation of the purified mixture of the variants with iodoacetamide after reduction with dithiothreitol identified three disulfides per 32,000-Da monomer. Urea gel electrophoresis revealed that the heterogeneity of lysyl oxidase persists after reduction and alkylation, indicating that disulfide isomers are not the bases of the enzyme heterogeneity.