Use of an electronic tongue and HPLC with electrochemical detection to differentiate molds in culture media.

A study was conducted to further evaluate an electronic tongue, using high-performance liquid chromatography (HPLC) with electrochemical (EC) and UV detection as a reference method. The electronic tongue consisted of four working electrodes made of different metals and arranged in a standard three-electrode configuration. Pulses of voltage were applied to the metals, and the current responses were sampled and collected in a data matrix. The objectives of the present investigation were to examine the ability of the electronic tongue to distinguish between two mold species growing in three different media, and to obtain support for the hypothesis that the device actually discriminates between different redox-active metabolites produced by the molds. Peak areas in EC and UV HPLC chromatograms were collected in a data matrix. The electronic tongue data and the EC and UV data were then subjected to principal component analysis (PCA). A number of peaks in the HPLC-EC chromatograms indicated that the growth media contained redox-active metabolites. Moreover, PCA of peak areas in EC chromatograms revealed differences between the distribution of redox-active metabolites produced by the two species and between the three culture media. The same pattern was apparent in a PCA score plot of electronic tongue data. The peaks in the UV and EC chromatograms differed, and these were also shown by the PCA score plots.

Use of an electronic tongue to analyze mold growth in liquid media.

The feasibility of employing an electronic tongue to measure the growth of mold in a liquid medium was studied. We used the electronic tongue developed at Linköping University, which is based on pulsed voltammetry and consists of an array of different metal electrodes. Instead of focusing on a single parameter, this device provides information about the condition or quality of a sample or process. Accordingly, the data obtained are complex, and multivariate methods such as principal component analysis (PCA) or projection to latent structures (PLS) are required to extract relevant information. A gas chromatographic technique was developed to measure ergosterol content in mold biomass and was subsequently used as a reference method to investigate the ability of the electronic tongue to measure the growth of mold in liquid media. The result shows that the electronic tongue can monitor mold growth in liquids. In PLS analysis, the electronic tongue signals correlate well with the amount of ergosterol in the mold biomass as well as the microbially induced changes in the pH of the medium.

Analysis of bacterial vaginosis-related amines in vaginal fluid by gas chromatography and mass spectrometry.

The presence of various amines in vaginal fluid from women with malodorous vaginal discharge has been reported before. The investigations have used several techniques to identify the amines. However, an optimized quantification, together with a sensitive analysis method in connection with a diagnostic procedure for vaginal discharge, including the syndrome of bacterial vaginosis, as defined by the accepted "gold standard," has not been done before. We now report a sensitive gas chromatographic and mass spectrometric method for identifying the amines isobutylamine, phenethylamine, putrescine, cadaverine, and tyramine in vaginal fluid. We used weighted samples of vaginal fluid to obtain a correct quantification. In addition, a proper diagnosis was obtained using Gram-stained smears of the vaginal fluid that were Nugent scored according to the method of Nugent et al. (R. P. Nugent et al., J. Clin. Microbiol., 29:297-301, 1991). We found that putrescine, cadaverine, and tyramine occurred in high concentrations in vaginal fluid from 24 women with Nugent scores between 7 and 10. These amines either were not found or were found only in very low concentrations in vaginal fluid from women with Nugent scores of 0 to 3. There is a strong correlation between bacterial vaginosis and the presence of putrescine, cadaverine, and tyramine in high concentrations in vaginal fluid.

Abnormal glucose levels found in transportation accidents.

BACKGROUND: The Federal Aviation Administration's Office of Aerospace Medicine is responsible for the certification of pilots with diabetic conditions. The present study evaluated the use of postmortem vitreous humor and urine glucose levels in transportation accident fatalities as indicators of potentially incapacitating medical conditions or performance impairment. METHODS: Vitreous humor and/or urine from 192 accident fatalities were analyzed for glucose using a hexokinase method. Cases with values below the lower limit of detection (10 mg x dl(-1)) and above 3 standard deviations (SD) from the mean were not included in the final statistics. All cases more than 5 SD above the mean were deemed abnormal and a full case history was evaluated based on the available medical history. RESULTS: The mean vitreous humor glucose concentration was 30+/-21 mg x dl(-1) (N=98), while it was 27+/-16 mg x dl(-1) in urine (N=127). Of the 192 cases, 9 were identified as having abnormal glucose levels. Abnormal glucose levels were found in 5 of the 8 cases with a known diabetic condition. Glycosuria or low renal threshold was reported in 2 fatal pilots; 1 of these pilots had an abnormal glucose level. CONCLUSIONS: Hyperglycemia can be established from the vitreous humor and urine glucose levels. All of the abnormal glucose cases detected were previously identified during the medical certification process or had a medical reason for the abnormal level. Elevated vitreous humor and urine glucose levels have proven useful in identifying individuals with a pre-existing diabetic condition that might have been a factor in the accident.

Determination of group parameters for organically bound chlorine, bromine and iodine in precipitation

The presence of organically bound halogens in precipitation was studied by first adsorbing organics on activated carbon and then analysing the chloride, bromide and iodide formed during combustion of the carbon. A standard instrument for the group parameter AOX (adsorbable organic halogens) was used for the combustion. The halides formed were trapped in an alkaline solution and analysed by capillary zone electrophoresis. The method described enabled determination of sub-ppb concentrations of the group parameters AOCl, AOBr and AOI (adsorbable organic chlorine, bromine and iodine, respectively). Analysis of rain and snow collected at different sites in Europe showed that organochlorines were responsible for the major part of the AOX content in all samples collected. Organically bound bromine was found in sub-ppb concentrations in all of the samples, whereas organic iodine was detected in only two of the samples.

Determination of the molecular weight of fulvic acids by UV/VIS spectroscopy

Partial least squares (PLS) modeling was applied to investigate number-average molecular weights (Mn) and weight-average molecular weights (Mw) of fulvic acids (FAs) in relation to the corresponding UV/VIS spectra. The Mn and Mw values were determined by size exclusion chromatography (SEC). The impact of pH control, wavelength range and density as well as smoothing and derivation of spectra were tested. It was found that PLS models based on absorbance spectra can be a fast and powerful complement to existing techniques employed for determination of molecular weights of FAs. Control of pH of the FA solutions is important for the performance of the models. The models were also compared with the best univariate alternatives.

Fractionation of halogenated organic matter present in rain and snow

Organic matter in samples of rain and snow from Sweden, Poland, Germany and the Republic of Ireland was fractionated by employing a series of filtration, purging, evaporation and extraction steps. Determinations of the group parameter AOX (adsorbable organic halogens) in aqueous phases and EOX (extractable organic halogens) in organic phases showed that halogenated organic matter present in bulk precipitation is composed of several different groups of compounds. The largest amounts of organically bound halogens were found in fractions of relatively polar and non-volatile to semivolatile compounds. In particular, a significant part of the AOX could be attributed to alkaline-labile organic bases. Gas chromatographic analysis of different organic extracts in the chlorine channel of an atomic emission detector (AED) resulted in chromatograms with few distinct peaks, and analysis in the bromine channel did not produce any distinct peaks. Chlorinated acetic acids were the most abundant halogenated organic acids, and chlorinated alkyl phosphates were normally responsible for the largest peaks in the chlorine chromatogram of neutral, hexane-extractable compounds. When analysing volatiles, 1,4-dichlorobenzene and a thus far unidentified chloroorganic compound often caused the largest response in the chlorine channel of the AED system.

Determination of low molecular weight organic acids in soil solution by HPLC.

An HPLC method employing an ion exclusion column was developed for the determination of low molecular weight organic acids in soil solution. The method includes extensive sample pretreatment using ultrafiltration and cation exchange. The method showed linear calibration graphs (r>0.99) and the limits of detection in the range 0.1-26 muM. The recovery of eleven added acids ranged from 89 to 102%. Soil solutions of five horizons of a podzolised soil were analysed. The results showed that these compounds made up 1-3% of the dissolved organic carbon and 0-14% of the acidity. Identification of the major acids was also carried out by capillary zone electrophoresis.

Determination of the carboxyl content in humic substances by methylation.

The carboxyl content of different fulvic acids was estimated by means of a methylation technique. The procedure involved methylation by diazomethane followed by base catalyzed hydrolysis, esterification with propionyl chloride and gas chromatographic analysis of the methyl ester formed. After optimization of each step, the whole sequence of reactions was performed using only a few milligrams of starting material. The method was applied to two fulvic acid samples of different origin (surface water and groundwater, respectively). The carboxylic content was estimated to about 3.5 meq/g material for the surface water fulvic acid and about 4.5 meq/g material for the groundwater fulvic acid. This estimates approximately 80% of the total content of acidic groups obtained for the same materials by using potentiometric titration.

Impact of bleached kraft mill effluents on drinking water quality.

Bleaching effluents from kraft pulp mills contain large quantities of chlorinated organic compounds, some of which are mutagenic. Mutagenic chloro-organic compounds are also formed as by-products in chlorination of drinking water. The work reported here was a combined field and laboratory study aimed at comparing the evidence of health risks from pulp mill contaminants in drinking water, with corresponding evidence from normal, chlorine disinfection by-products. The study was performed in a Swedish river basin with a large, public water works located downstream from a bleached kraft mill. Chemical analyses (gas chromatography and determination of adsorbable organic halogen) and bioassays for mutagenic activity (bacterial and mammalian cell bioassays) were performed on samples of river water, drinking water and laboratory produced drinking water. The study showed that the bleached kraft effluents caused a considerable, long-range transport of chloro-organic substances in the receiving waters, and a substantial increase in the total amount of organic chlorine in drinking water produced downstream from the mill. As regards Ames mutagenic compounds, however, chlorination of naturally occurring humic substances during the chlorine disinfection step in drinking water production, proved to be a far more important source. The contribution of volatile chloro-organic compounds from the kraft mill was also much smaller than the contribution from normal disinfection by-products. The chromosome aberration tests gave no clear evidence of a positive response for any of the samples tested.

Male reproductive function in long-term survivors of childhood cancer.

We evaluated reproductive function in 27 male long-term survivors of childhood cancer treated during the prepubertal and pubertal period. Sperm samples were obtained from 23 patients; four who refused to provide specimens indicated that they had fathered normal healthy children. Thirteen patients were 12 years old or younger at the time of diagnosis and initiation of therapy. Chemotherapy was calculated according to the cumulative amount of drug administered and correlated with the surface area. Sterility was associated with large doses of single alkylating agents or reduced doses administered with other agents in combination regimens. It was noted in boys treated in both the prepubertal and pubertal period. Sterility was also observed in patients who received testicular radiation alone or in combination with chemotherapy. However, it was not an inevitable consequence in all patients, despite treatment with similar or identical regimens. Fertility potential could not be predicted by clinical examination (testicular size) or gonadotrophin and testosterone values. The results were compared to published reports of treatment-induced sterility in adult males. Additional investigations are required to establish more accurate correlations of dosage with reproductive potential.

A comparison of methods for concentrating mutagens in drinking water--recovery aspects and their implications for the chemical character of major unidentified mutagens.

A comparison of techniques for concentrating mutagenic compounds in drinking water has shown that XAD-2 adsorption and dichloromethane extraction have acceptable and almost identical enrichment properties, while purging at an elevated temperature is inappropriate in this context. Quantitatively, the most important drinking water mutagens could only be adsorbed (extracted) after acidification of the water, and even then recovery was far from complete. Recovery experiments with known mutagens from pulp mill effluents have shown that none of the major chlorination-stage mutagens identified thus far can explain the mutagenic activity of extracts from neutral or acidified chlorinated drinking water.

Stress reduction. A spectrum of strategies in pediatric oncology nursing.

It is important to provide resources to promote effective coping mechanisms for dealing with the stresses encountered by children, families, and staff in a pediatric oncology setting. Knowledge of how such resources can be used to the maximum advantage must be combined with the utilization and development of support services.

Direct liquid chromatographic separation of enantiomers on immobilized protein stationary phases. IV. Molecular interaction forces and retention behaviour in chromatography on bovine serum albumin as a stationary phase.

Chromatography with the use of immobilized bovine serum albumin as a stationary phase and aqueous buffer systems as eluents has proved to be a highly selective method, capable of separating structurally very closely related compounds. Retention can be effectively regulated by changes in at least three independent parameters of the mobile phase, which may be used for an optimization of separation factors. Particularly, the enantioselective properties of the chiral stationary phase have been demonstrated to be useful for the analytical resolution of a variety of racemates into enantiomers. From the variation of the retention behaviour with substituent effects, as well as the mobile phase composition, some indications regarding the molecular interaction forces regulating the substrate-protein equilibria have been obtained.

Direct optical resolution of a series of pharmacologically active racemic sulfoxides by high-performance liquid affinity chromatography.

A series of pharmacologically active racemic sulfoxides was investigated with respect to optical resolution by an affinity chromatographic technique based on enantioselective interactions with immobilized bovine serum albumin. The results show that very small changes in the molecular structure of a drug, at a large distance from the asymmetric center, can drastically alter not only its affinity for the albumin molecule but also the enantioselectivity in the reversible binding process. Apart from being an excellent, rapid method for studies of drug binding to and transport by serum albumins, it has a large potential application as a chromatographic technique for the determination of enantiomeric purity as well as stereoselective uptake processes of drugs.