Candida virulence and ethanol-derived acetaldehyde production in oral cancer and non-cancer subjects.

OBJECTIVES: To compare biofilm-forming ability, hydrolytic enzymes and ethanol-derived acetaldehyde production of oral Candida isolated from the patients with oral cancer and matched non-oral cancer. MATERIAL AND METHODS: Fungal biofilms were grown in RPMI-1640 medium, and biofilm mass and biofilm activity were assessed using crystal violet staining and XTT salt reduction assays, respectively. Phospholipase, proteinase, and esterase production were measured using agar plate method, while fungal acetaldehyde production was assessed via gas chromatography. RESULTS: Candida isolated from patients with oral cancer demonstrated significantly higher biofilm mass (P = 0.031), biofilm metabolic activity (P < 0.001), phospholipase (P = 0.002), and proteinase (P = 0.0159) activity than isolates from patients with non-oral cancer. High ethanol-derived acetaldehyde-producing Candida were more prevalent in patients with oral cancer than non-oral cancer (P = 0.01). In univariate regression analysis, high biofilm mass (P = 0.03) and biofilm metabolic activity (P < 0.001), high phospholipase (P = 0.003), and acetaldehyde production ability (0.01) were significant risk factors for oral cancer; while in the multivariate regression analysis, high biofilm activity (0.01) and phospholipase (P = 0.01) were significantly positive influencing factors on oral cancer. CONCLUSION: These data suggest a significant positive association between the ability of Candida isolates to form biofilms, to produce hydrolytic enzymes, and to metabolize alcohol to acetaldehyde with their ability to promote oral cancer development.

Evaluation and application of a paper-based device for the determination of reactive phosphate in soil solution.

The evaluation and validation of a new low-cost microfluidic paper-based analytical device (µPAD) for the determination of reactive phosphate in soil solution is described. This device allows up to 15 replicate measurements of reactive phosphate on one credit card-sized device and requires only a desktop or hand scanner for signal detection and quantification. The proposed method showed a linear response between 0.1 and 1.0 mg L and between 1.0 and 10.0 mg L P with a limit of detection of 0.05 mg L P. When applied to the analysis of soil solution, there was excellent agreement between results obtained using the µPAD and those obtained by a reference spectrophotometric method, as indicated by the following regression equation: [P] = (0.997 ± 0.005)[P] - (0.020 ± 0.008) ( = 0.997; = 110). It was found that the ambient temperature storage stability of the µPAD could be extended to 15 d by incorporating a removable polymeric interleaving sheet between the adjacent paper layers of the device. The observed sensitivity of the µPADs to sunlight, which was manifested by photoreduction of the chromogenic molybdate reagent used in the assay, was overcome by preparing the µPADs with an ultraviolet-filtering laminating material. The proposed method is rapid, with a reaction time of only 10 min, is easy to perform, and is suitable for application in the field.

Determination of Henry's law constants of phenols by pervaporation-flow injection analysis.

A novel dynamic nonequilibrium technique for the determination of Henry's law constant (HLC) of phenols based on pervaporation-flow injection (PFI) is described. A linear relationship between HLC and the amount of phenol measured by a detector in the acceptor line of a PFI system was demonstrated. This relationship was constructed using five frequently encountered phenols (phenol, 2,4-dimethylphenol, 2,4-dichlorophenol, 2-chlorophenol, and 2,3-dimethylphenol) and used for the determination of the HLC of three other phenols (2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol). The HLC of all eight phenols were also determined by the single equilibrium static technique (SEST). Fairly good agreementwas observed between both techniques regarding the HLC of 2,4,6-trichlorophenol, 2-methylphenol, and 3-methylphenol. On the basis of the results obtained, it was concluded that the PFI technique offers considerable advantages over SEST in terms of precision, speed, labor intensity, and possibilities for automation.

Determination of rate constants and reaction orders with an open-closed flow-injection configuration.

A new, very useful application of open-closed configurations to kinetic studies is reported. The multipeak recordings provided by the manifold used, which features a single conventional photometric detector, were used to calculate the rate constants and reaction orders of a chemical system, namely the ligand displacement reaction between the cobalt(II)-EGTA complex and PAR.

End effects in flow-analysis and process systems.

The "end effects" in flow-analysis and process systems are investigated theoretically on the basis of the axially-dispersed plug-flow model. Three-section systems consisting of reactor, fore- or after-section and additional section are used. In the additional section back-mix flow is assumed to exist. The corresponding Peclet number has been found to be 0.01. The difference between the system responses to a delta-function input signal for finite and infinite length of the fore- or after-section is studied. Both the statistical moments of the system responses and the actual response curves are used for that purpose. The results can be used to evaluate the length of the fore- and after-sections needed in real flow-analysis and process systems in order that the phenomena taking place downstream or upstream of these two sections, respectively, will not play an important role in the system response.