Interaction between dyes and polyelectrolytes, 5. Effect of organic and inorganic salts on metachromasy of methylene blue

The effect of alkali metal chlorides and 1-substituted 3-carbamoylpyridinium bromides ( 2a – d ) on the metachromatic behavior of methylene blue ( 1 ) induced by poly(potassium styrenesulfonate) (PSS) and poly(potassium vinyl sulfate) (PVS) was investigated spectrophotometrically. The size of hydrated ion and the hydrophobicity of substituent were significant factors for inorganic and organic salts, respectively. Effect of these salts on the metachromasy was characteristic of each polyanion used. A peculiar phenomenon that the metachromasy of the PSS- 1 system was enhanced on addition of small amounts of 1-dodecyl-3-carbamoylpyridinium bromide ( 2d ) was observed.     

The effects of organic solvents on trimethadione n-demethylation in rats

Many organic solvents are frequently used as support solvents to dissolve chemicals in the study concerning drug metabolism mediated by cytochrome P450. However, some organic solvents used as the support solvents affect the chemical's metabolism. It has been reported that some organic solvents are metabolized by CYP2E1 or inhibit its enzymatic reaction. In this study we investigated the effects of organic solvents, such as acetonitrile (AN), dimethylsulfoxide (DMSO), ethanol (EtOH), methanol (MeOH), polyethylene glycol (PEG) and propylene glycol (PG) on TMO (trimethadione) metabolism, which is mainly mediated by CYP2E1 in the rat. In the in vivo study, male SD rats were pretreated with an organic solvent intraperitoneally at a dosage of 0.5, 1 or 2 mmol/kg 1 hour before TMO administration orally at the dose of 4 mg/kg. After 2 hours, serum concentrations of TMO and DMO were determined by gas chromatography/flame detection (CG/FTD) and the serum DMO/TMO ratio was employed for assessment of the metabolic capacity of TMO. In the in vitro study, hepatic microsomal fraction was used as an enzyme source of TMO N-demethylase and enzyme activities were determined by the production of DMO. Pretreatment with DMSO and PG decreased the DMO/TMO ratio in a dose-related manner in vivo study. Furthermore, in vitro study TMO N-demethylase activity was inhibited by DMSO, EtOH and PG with different potency in a concentration related manner. However, no remarkable effects were observed by AN or PEG both in vivo and in vitro study. These results indicated that there are variations in the inhibitory effects of these organic solvents on CYP2E1-mediated metabolism and AN and PEG will be useful solvents to dissolve chemicals in the metabolic study mainly mediated by CYP2E1.     

The role of co-operativity in determining the binding behaviour of hetero-charged polyanions with metachromatic dyes

The binding of acridine orange to carboxyl and sulfate containing polyanions has been investigated by fluorescence spectroscopy. Particular attention has been given to solutions containing both carboxyl and sulfate groups in two different situations, first where both types of site are present attached to the same polymer backbone in a regular repeating structure (heparin), and secondly where individual polymer chains carry exclusively one type of site (hyaluronic acid/K-carrageenan mixtures). Greatly differing behaviour of the binding profiles as the concentrations of components were reduced have been explained in terms of the strong co-operativity of the dye-binding process. The carboxyl and sulfate sites of heparin appear to be equivalent in binding strength, while those of the polycarboxylate polysulfate mixture are no longer equivalent, binding profiles being dominated by the strong binding sulfate group.     

Interaction between dyes and polyelectrolytes, 8. Effect of polyanions on the mixed dimer formation of cationic dyes

The effect of polyanions on the formation of mixed dimers of methylene blue ( 1 ) and trypaflavine ( 2 ), methylene blue ( 1 ) and phenosafranine ( 3 ), and methylene blue ( 1 ) and pyronine G ( 4 ) was investigated spectrophotometrically. The following polyanions were used: poly(potassium styrenesulfonate) (PSS), poly(potassium vinyl sulfate) (PVS), and poly(sodium acrylate) (PAA). On addition of polyanions, the formation of mixed dimers was enhanced largely. Thermodynamic parameters inferred that the enhancement of the formation of mixed dimers in the presence of polyanions resulted from an entropic factor.     

Studies on the adsorption of anionic dyes on chitosan

Equilibrium adsorption measurements of three anionic dyes on chitosan, under acid conditions, show that there is a 1 : 1 stoichiometry for the interaction of sulfonic acid groups on the dyes with protonated amine groups of the chitosan for mono-, di- and trisulfonated dyes. Comparison of the extents of N-acetylation calculated from equilibrium dye adsorption values with those determined by IR spectroscopy, for a series of chitosan samples covering a wide range of N-acetylation values, demonstrates that equilibrium adsorption measurements may be used for the analysis of chitin and chitosan.     

A nondisposable microplate for use with organic solvents

Summary A nondisposable, or hard, multiwell microplate is described for use with small volumes of biological solutions containing organic solvents. The design of this teflon-coated, aluminum device resembles the 96-well layout of the disposable variety of tissue culture microplates. The reusable, hard microplate has been specifically developed to hold and evaporate volatile organic solvents from aliquots of crude sample extractions or partitions intended for testing in various in vitro biological screening assays. This device is a valuable adjunct for converting numerous small volumes of nonpolar or nonaqueous dissolved compounds into reconstituted solutions containing acceptable assay solvents.     

Renal effects of chronic exposure to organic solvents. A clinical controlled trial

Chronic effects of organic solvents on renal function were measured by creatinine clearances and urinary excretion rates of beta 2-microglobulin and albumin. Forty-three male printing trade workers occupationally exposed to different organic solvents for 9-25 years were compared with 43 age-matched male controls. No differences were found either in creatinine clearances or average basal levels of beta 2-microglobulin and albumin excretion rates, whereas a positive relation could be demonstrated between alcohol consumption on the day before the trial and urinary excretion rate of albumin. This investigation did not reveal any adverse renal effects of moderate chronic exposure to organic solvents in a group of active trade workers.     

Tolerance of bacteria to organic solvents

Organic-solvent-tolerant bacteria are a relatively novel group of extremophilic microorganisms. They overcome the toxic and destructive effects of organic solvents due to the presence of various adaptive mechanisms. Extensive studies done on the toluene tolerance of certain Pseudomonas strains have led to an understanding of the mechanisms of organic solvent tolerance involving novel adaptations such as the toluene efflux pumps, cis-trans isomerisation of membrane fatty acids, rapid membrane repair mechanisms, etc. Organic-solvent-tolerant mutants of Escherichia coli have been constructed and genes enhancing such tolerance characterised. However, there is practically no information available on the tolerance mechanisms of the reported Gram-positive organic-solvent-tolerant bacterial strains like Bacillus, Rhodococcus and Arthrobacter. This review discusses the general aspects of organic-solvent-tolerant bacteria, their history, biodiversity, mechanisms of tolerance and proposes certain probable adaptations of Gram-positive bacteria in tolerance to organic solvents.     

Behavioral toxicology of volatile organic solvents. I. Methods: acute effects of toluene

Behavioral toxicity of toluene has been assessed in mice. Because of its small size the mouse can be confined in a 20 l hermetically sealed chamber for several hours. Toluene was introduced through a port and volatilized by a hot-plate. Samples of chamber air for analysis were taken through another port. A smaller mesh cage held the mouse within the larger chamber. Schedule-controlled responding was developed by arranging that a response, breaking a beam of light, was followed by milk under an Fl 60 sec schedule. Responding was much more rapid in the presence of stimuli correlated with the Fl schedule than when the schedule was not operating. Standard sessions consisted of alternating series of 8 consecutive Fl 60 sec and inter-series 30 min time-outs. Toluene disappeared from the atmosphere of the unopened empty chamber at the rate of 0.2%/hr. When the mouse cage was in the chamber the disappearance was 1.5%/hr and when a mouse was also present it was 3.7%/hr. Concentration-effect curves were determined by exposing a mouse to incremental additions of toluene at 30 min intervals. Toluene increased the rate of responding in most mice at levels of about 700 ppm. Higher concentrations progressively reduced responding. The ED50 (the concentration reducing responding by 50%) averaged 1657 ppm in 10 mice. In the appendix, principles for the assessment of hazard from results of this type are presented. It is estimated that there is a 1/1000 chance of the responding of a mouse being reduced by as much as 10% by a concentration of toluene of 69 ppm.     

Exposure to organic solvents and adverse pregnancy outcomes

BACKGROUND: Organic solvents are among the most common exposures in the workplace. Our objective was to elaborate the relationship between prenatal occupational solvent exposure and fetal growth as well as duration of pregnancy, and to quantify the impact of occupational organic solvent exposure. METHODS: We conducted a population-based study of 1670 singleton newborns of women who participated in The Finnish Prenatal Environment and Health Study after their delivery (response rate 94%) and who were working during pregnancy (65%). Exposure information was based on questions about exposure to solvents at work before and during pregnancy. The health outcomes, based on information from a questionnaire and the Finnish Medical Birth Registry, were low birth weight (<3000 g), small-for-gestational-age and preterm delivery (<37 weeks). RESULTS: In logistic regression analysis, the risk of the baby being small-for-gestational-age was related to any exposure to solvents 3 months before or during pregnancy with an adjusted odds ratio (OR) of 1.67 [95% confidence interval (CI) = 1.02-2.73]. Also the adjusted OR for low birth weight was elevated with exposure, although it did not reach statistical significance (1.17; 95% CI = 0.71-1.93). The population attributable fraction for small-for-gestational-age was 2.3% for all pregnant women. CONCLUSIONS: Work exposure to organic solvents may reduce intrauterine growth by increasing the risk of the baby being small-for-gestational-age.     

Enhancement of the photostability and retention time of indocyanine green in sentinel lymph node mapping by anionic polyelectrolytes

Sentinel lymph node (SLN) biopsy techniques have been widely used in the diagnosis of cancer metastasis because lymph node metastasis is one of the most important prognostic signs. Indocyanine green (ICG) has potential application as a molecular imaging probe for SLN mapping due to its fluorescent properties emitting in the near-infrared (NIR) region, where light transmission through biological tissue is maximized. However, its low photostability in an aqueous solution at the physiological temperature and its rapid diffusion behavior through SLN into the second lymph node have limited its wide use in real clinical fields. In this study, we developed a new NIR imaging contrast system consisting of ICG and poly (γ-glutamic acid) (γ-PGA) polymers for efficient sentinel lymph node mapping. By a combination of clinically used ICG and the biocompatible anionic polyelectrolyte, γ-PGA, the photostabilities of aqueous ICG solutions at room and body temperatures were drastically enhanced. When the ICG/γ-PGA complex was injected subcutaneously into the front paw of a mouse, it entered the lymphatics and migrated to the axillary sentinel lymph node (SLN) within 2 min. Furthermore, the NIR fluorescent signal intensity and retention time of ICG/γ-PGA complex in lymph node were superior to those of ICG only. In addition, a histofluorescentstudy of the SLN resected under NIR imaging revealed that ICG and γ-PGA were co-localized in the lymph node.Taken together, the experimental results on the enhanced photostability and retention time of the ICG/γ-PGA complex provide strong evidence that it has promising potential for improved sentinel lymph node mapping.     

Interaction between dyes and polyelectrolytes, 14. Triplet energy transfer in a cationic dye-polyanion system

Polymers with different fractions of azobenzene residues were prepared by radical copolymerization of methacrylic acid with 4′-phenylazomethacrylanilid. The triplet excitation energy transfer from methylene blue ( 1 ) to the azobenzene residues in the polymers was investigated by using the 1 -photosensitized cis → trans isomerization of the azobenzene residue. The efficiency of the triplet excitation energy transfer from 1 to 4-(4′-phenylazoanilinocarbonyl)butanoic acid ( 4 ) as a monomer model compound. The number of azobenzene residues per polymer molecule and the molecular weight of the polymer were important factors for the efficient triplet excitation energy transfer. On addition of NaCl the energy transfer efficiency was lowered, suggesting that the binding of 1 to the polymer by electrostatic forces plays an important role. Binding of 1 to the polymers was investigated spectrophotometrically. Correlation with the binding of 1 to the polymers and the efficiency of triplet excitation energy transfer between 1 and azobenzene residues in the polymers is discussed.     

Interaction between dyes and polyelectrolytes, 2. Structural effect of polyanions on the methylene blue binding

The structural effect of polyanions on the binding type of methylene blue ( 1 ) was investigated spectrophotometrically. 1 was bound to poly(potassium styrenesulfonate) (PSS) and poly(sodium 4-vinylphenylsulfate) (SVS) in the dimeric or slightly aggregated form and to poly(sodium vinylsulfonate) (SVF) and poly(potassium vinyl sulfate) (PVS) in the highly aggregated (polymeric) form. It was found that the flexibility of polyanions plays an important rǒle in the aggregation of bound 1 and that the difference between ? SO and ? OSO as binding site is not a significant factor.     

The effects of organic solvents and temperature on the desorption of yeast 3-phosphoglycerate kinase from immunoadsorbent.

Physicochemical parameters governing the elution of yeast 3-phosphoglycerate kinase from its immunoadsorbent were studied. Non-denaturing elution conditions were determined (alkali medium containing 50%, v/v, ethylene glycol) and the method was applied to one-step isolation of enzyme from a crude yeast preparation.     

Interaction between dyes and polyelectrolytes, 9. Effect of polyanions on alkaline fading reaction of methylene blue

The effect of polyanions poly(potassium vinyl sulfate) (PVS), poly(sodium acrylate) (PANa), and poly(potassium p-styrenesulfonate) (PSS), on the alkaline fading reaction of methylene blue ( 1 ) was investigated. The fading rate of 1 was extremely retarded on addition of polyanions. The binding type of 1 to polyanions was investigated spectrophotometrically by following the changes in the molar absorption coefficient (ε) at 664nm band. The relationship between the binding type and the fading rate of 1 in aqueous alkaline solution of polyanions is discussed.     

The effects of organic solvents on poly(ADP-ribose) polymerase-1 activity: implications for neurotoxicity

Poly(ADP-ribose) polymerase-1 (PARP-1; EC 2.4.2.30), also termed as poly(ADP-ribose) synthetase, is a key enzyme in the recognition and repair of damaged DNA. Several conditions (e.g., ischemia-reperfusion or chemical-induced injury) have been shown to overactivate PARP-1, causing neurodegeneration and necrotic or apoptotic cell death from NAD+ and ATP depletion. In contrast, inhibitors of PARP-1 have been shown to have a neuroprotective effect by ameliorating this response. The purpose of this study was to determine the effects of three routinely used organic solvents (ethanol, methanol, and dimethyl sulfoxide (DMSO)) on the activity of purified PARP-1. A dose-response was examined with each of these solvents. A 112% and 82% increase in PARP-1 activity was observed with 15% ethanol and 20% methanol, respectively. In contrast, a near 20% decrease in the activity was observed with 4% DMSO. Kinetic analysis revealed that the maximal velocity remained unchanged with increasing concentrations of DMSO up to 20%, indicating that DMSO is a competitive inhibitor of PARP-1. Thus, PARP-1 inhibition by DMSO depends on NAD+ concentration and in some pathological processes might be significant even at low DMSO concentrations. Our findings suggest that the interpretation of data from dose-response studies obtained when using common organic solvents may be dramatically skewed, either exaggerating the inherent toxicity of the compound or masking its potential for damage.     

Detection of charges and their distribution on dialysis membranes with cationic/anionic dyes using confocal laser scanning microscopy.

Methods for the detection of positive or negative charges on the surface of biomaterials/membranes and inside a membrane are important for the characterisation of such materials. We tested different dyes and optimized staining procedures. Under standardized conditions negatively charged membranes were stained with cationic triarylmethane compounds such as crystal violet and positively charged membranes with the anionic anthraquinone dye anthralan blue B. There was no staining of uncharged cellulose membranes. The applicability of these methods was demonstrated on membranes coated to varying degrees with charged compounds such as heparin, these changes in charge being detectible quantitatively by photometry. The distribution of charges inside a membrane was detected by optical sectioning across the stained (FITC labelled poly-L-lysine) membrane using confocal laser scanning microscopy (LSM). LSM offers a completely new application possibility in biomaterial and biocompatibility research.