General anesthesia can be caused by various, chemically very different molecules, while several other molecules, many of which are structurally rather similar to them, do not exhibit anesthetic effects at all. To understand the origin of this difference and shed some light on the molecular mechanism of general anesthesia, we report here molecular dynamics simulations of the neat dipalmitoylphosphatidylcholine (DPPC) membrane as well as DPPC membranes containing the anesthetics diethyl ether and chloroform and the structurally similar non-anesthetics n-pentane and carbon tetrachloride, respectively. To also account for the pressure reversal of anesthesia, these simulations are performed both at 1 bar and at 600 bar. Our results indicate that all solutes considered prefer to stay both in the middle of the membrane and close to the boundary of the hydrocarbon domain, at the vicinity of the crowded region of the polar headgroups. However, this latter preference is considerably stronger for the (weakly polar) anesthetics than for the (apolar) non-anesthetics. Anesthetics staying in this outer preferred position increase the lateral separation between the lipid molecules, giving rise to a decrease of the lateral density. The lower lateral density leads to an increased mobility of the DPPC molecules, a decreased order of their tails, an increase of the free volume around this outer preferred position, and a decrease of the lateral pressure at the hydrocarbon side of the apolar/polar interface, a change that might well be in a causal relation with the occurrence of the anesthetic effect. All these changes are clearly reverted by the increase of pressure. Furthermore, non-anesthetics occur in this outer preferred position in a considerably smaller concentration and hence either induce such changes in a much weaker form or do not induce them at all.
- MeSH
- 1,2-dipalmitoylfosfatidylcholin chemie MeSH
- anestetika celková * farmakologie MeSH
- anestezie * MeSH
- chloroform chemie MeSH
- lipidové dvojvrstvy chemie MeSH
- membrány MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- 1,2-dipalmitoylfosfatidylcholin MeSH
- anestetika celková * MeSH
- chloroform MeSH
- lipidové dvojvrstvy MeSH
While microRNAs are considered as excellent biomarkers of various diseases, there are still several remaining challenges regarding their isolation. In this study, we aimed to design a novel RNA isolation method that would help to overcome those challenges. Therefore, we present a novel phenol/chloroform-free, low-cost method for miRNA extraction. Within this method, RNA is extracted from cell lysate with an isopropanol/water/NaCl system, followed by solid-phase extraction using TiO2 microspheres to effectively separate short RNAs from long RNA molecules. We also demonstrated the pH-dependent selectivity of TiO2 microspheres towards different sizes of RNA. We were able to regulate the size range of extracted RNAs with simple adjustments in binding conditions used during the solid-phase extraction.
- Klíčová slova
- TiO2, miRNA isolation, phenol/chloroform-free, short RNA extraction,
- MeSH
- chloroform chemie MeSH
- fenol * chemie MeSH
- fenoly MeSH
- mikro RNA * genetika MeSH
- titan MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chloroform MeSH
- fenol * MeSH
- fenoly MeSH
- mikro RNA * MeSH
- titan MeSH
- titanium dioxide MeSH Prohlížeč
Chloroform is one of the common disinfection byproducts, which is not susceptible to degradation and poses great health concern. In this study, the chloroform removal efficiencies and contributions of sorption, microbial degradation, plant uptake, and volatilization were evaluated in six model constructed wetlands (CWs). The highest chloroform removal efficiency was achieved in litter-added CWs (99%), followed by planted (46-54%) and unplanted CWs (39%). Mass balance study revealed that sorption (73.5-81.2%) and microbial degradation (17.6-26.2%) were the main chloroform removal processes in litter-added CWs, and that sorption (53.6-66.1%) and plant uptake (25.3-36.2%) were the primary contributors to chloroform removal in planted CWs. Around 60% of chloroform got accumulated in the roots after plant uptake, and both transpiration and gas-phase transport were expected to be the drivers for the plant uptake. Sulfate-reducing bacteria and methanogens were found to be the key microorganisms for chloroform biodegradation through cometabolic dechlorination, and positive correlations were observed between functional genes (dsrA, mcrA) and biodegradation rates. Overall, this study suggests that wetland is an efficient ecosystem for sustainable chloroform removal, and that plant and litter can enhance the removal performance through root uptake and microbial degradation stimulation, respectively.
- MeSH
- adsorpce MeSH
- Bacteria genetika metabolismus MeSH
- bakteriální geny MeSH
- biodegradace MeSH
- biotransformace MeSH
- chemické látky znečišťující vodu analýza MeSH
- chloroform chemie MeSH
- čištění vody * MeSH
- kinetika MeSH
- mokřady * MeSH
- poločas MeSH
- volatilizace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chemické látky znečišťující vodu MeSH
- chloroform MeSH
Experimental and theoretical specific optical rotations (OR) of anhydro, epithio, and epiminoderivatives of methyl tetrofuranosides in chloroform solutions have been compared and used as a tool for exploring their conformational behavior. The potential energy surfaces of these saccharides with reduced flexibility were examined with the density functional theory and the MP2 and CCSD(T) wavefunctions methods. Theoretical ORs were obtained by Boltzmann averaging of values calculated for local minima. Resultant rotations could be used to assess the quality of the DFT and MP2 relative conformer energies. OR values calculated for equilibrium geometries in vacuum were significantly improved when the solvent was accounted for by a polarizable continuum model and first and diagonal second OR derivatives were used for an anharmonic vibrational averaging. The DFT used as a default method reproduced the experimental data fairly well. A modified B3LYP functional containing 70% of HF exchange further improved the results. Because of the strong dependence of OR on the conformation, not only the absolute configuration could be determined, but also the conformational populations were estimated. Likewise, the predicted dependence of OR on the light wavelength well agreed with experiment. The increasing precision of the contemporary computational methods thus makes it possible to relate the specific rotation to more detailed features in molecular structure.
- MeSH
- chloroform chemie MeSH
- furany chemie MeSH
- kvantová teorie MeSH
- molekulární konformace MeSH
- ohebnost (fyzika) MeSH
- optická otáčivost MeSH
- rozpouštědla chemie MeSH
- roztoky chemie MeSH
- termodynamika MeSH
- vibrace MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chloroform MeSH
- furany MeSH
- rozpouštědla MeSH
- roztoky MeSH
A comparison of the effects of ultrasound produced by low- and high-frequency ultrasonic apparatuses upon biological systems is one of the basic problems when studying ultrasound cavitation effects. One possibility for how to compare these effects is the indirect method which uses well-known physical quantities characterizing the interaction of ionizing radiation with matter and which also converts these quantities to one common physical quantity. The comparison was performed with two methods applied to the chemical dosimetry of ionizing radiation. The first method employed a two-component dosimeter which is composed of 50 % chloroform and 50 % re-distilled water (i.e. Taplin dosimeter). The other method used a modified iodide dosimeter prepared from a 0.5 M potassium iodide solution. After irradiation or ultrasound exposure, measurable chemical changes occurred in both dosimeters. The longer the exposure, the greater the chemical changes. These effects are described by the relationship of these changes versus the exposure times in both dosimeters. The UZD 21 ultrasonic disintegrator (with a frequency of 20 kHz, 50 % power output) was used as a low-frequency ultrasound source, and the BTL-07 therapeutic instrument (with a frequency of 1 MHz and intensity of 2 W/cm2) was used as a high-frequency cavitation ultrasound source. For comparison, a 60 Co gamma source was applied (60 Co, gamma energies of 1.17 and 1.33 MeV, activity of 14 PBq). Results of this study have demonstrated that the sonochemical products are generated during exposure in the exposed samples of both dosimeters for all apparatuses used. The amount of these products depends linearly upon the exposure time. The resulting cavitation effects were recalculated to a gray-equivalent dose (the proposed unit is cavitation gray [cavitGy]) based on the sonochemical effects compared to the effects of ionizing radiation from the 60 Co source.
- MeSH
- časové faktory MeSH
- chemické modely MeSH
- chloroform chemie účinky záření MeSH
- dávka záření * MeSH
- design vybavení MeSH
- jodid draselný chemie účinky záření MeSH
- koncentrace vodíkových iontů MeSH
- radioizotopy kobaltu * MeSH
- radiometrie přístrojové vybavení MeSH
- ultrazvuk * MeSH
- vztah dávky záření a odpovědi MeSH
- záření gama * MeSH
- Publikační typ
- časopisecké články MeSH
- srovnávací studie MeSH
- Názvy látek
- chloroform MeSH
- jodid draselný MeSH
- radioizotopy kobaltu * MeSH
The dynamic structure and potential energy surface of adenine...thymine and guanine...cytosine base pairs and their methylated analogues interacting with a small number (from 1 to 16 molecules) of organic solvents (methanol, dimethylsulfoxide, and chloroform) were investigated by various theoretical approaches starting from simple empirical methods employing the Cornell et al. force field to highly accurate ab initio quantum chemical calculations (MP2 and particularly CCSD(T) methods). After the simple molecular dynamics simulation, the molecular dynamics in combination with quenching technique was also used. The molecular dynamics simulations presented here have confirmed previous experimental and theoretical results from the bulk solvents showing that, whereas in chloroform the base pairs create hydrogen-bonded structures, in methanol, stacked structures are preferred. While methanol (like water) can stabilize the stacked structures of the base pairs by a higher number of hydrogen bonds than is possible in hydrogen-bonded pairs, the chloroform molecule lacks such a property, and the hydrogen-bonded structures are preferred in this solvent. The large volume of the dimethylsulfoxide molecule is an obstacle for the creation of very stable hydrogen-bonded and stacked systems, and a preference for T-shaped structures, especially for complexes of methylated adenine...thymine base pairs, was observed. These results provide clear evidence that the preference of either the stacked or the hydrogen-bonded structures of the base pairs in the solvent is not determined only by bulk properties or the solvent polarity but rather by specific interactions of the base pair with a small number of the solvent molecules. These conclusions obtained at the empirical level were verified also by high-level ab initio correlated calculations.
- MeSH
- chloroform chemie MeSH
- dimethylsulfoxid chemie MeSH
- konformace nukleové kyseliny MeSH
- methanol chemie MeSH
- metylace DNA * MeSH
- molekulární modely MeSH
- nukleotidy chemie MeSH
- párování bází * MeSH
- počítačová simulace MeSH
- voda chemie MeSH
- vodíková vazba MeSH
- zastoupení bazí MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chloroform MeSH
- dimethylsulfoxid MeSH
- methanol MeSH
- nukleotidy MeSH
- voda MeSH
Radioisotopes carbon 14 and chlorine 36 were used to elucidate the environmental role of trichloroacetic acid (TCA) formerly taken to be a herbicide and a secondary air pollutant with phytotoxic effects. However, use of 14C-labeling posed again known analytical problems, especially in TCA extraction from the sample matrix. Therefore--after evaluation of available methods--a new procedure using decarboxylation of [1,2-14C]TCA combined with extraction of the resultant 14C-chloroform with a non-polar solvent and its subsequent radiometric measurement was developed. The method solves previous difficulties and permits an easy determination of amounts between 0.4 and 20 kBq (10 - 500 ng g(-1)) of carrier-less [1,2-14C]TCA in samples from environmental investigations. The procedure is, however, not suitable for direct [36Cl]TCA determination in chlorination studies with 36Cl. Because TCA might be microbially degraded in soil during extraction and sample storage and its extraction from soil or needles is never complete, the decarboxylation method--i.e. 2 h TCA decomposition to chloroform and CO2 in aqueous solution or suspension in closed vial at 90 degrees C and pH 4.6 with subsequent CHCl3 extraction-is recommended here, estimated V < 7%. Moreover, the influence of pH and temperature on the decarboxylation of TCA in aqueous solution was studied in a broad range and its environmental relevance is shown in the case of TCA decarboxylation in spruce needles which takes place also at ambient temperatures and might amount more than 10-20% after a growing season. A study of TCA distribution in spruce needles after below-ground uptake shows the highest uptake rate into current needles which have, however, a lower TCA content than older needle-year classes, TCA biodegradation in forest soil leads predominatingly to CO2.
- MeSH
- chlor chemie MeSH
- chloroform chemie MeSH
- dekarboxylace MeSH
- ekosystém MeSH
- koncentrace vodíkových iontů MeSH
- kyselina trichloroctová analýza chemie metabolismus MeSH
- látky znečišťující půdu analýza MeSH
- monitorování životního prostředí metody MeSH
- nadzemní části rostlin chemie MeSH
- půda MeSH
- radioizotopy uhlíku chemie MeSH
- stromy MeSH
- teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chlor MeSH
- chloroform MeSH
- kyselina trichloroctová MeSH
- látky znečišťující půdu MeSH
- půda MeSH
- radioizotopy uhlíku MeSH
Insect cuticular hydrocarbons (CHCs) were probed by matrix-assisted laser desorption/ionization (MALDI) time-of-flight (TOF) mass spectrometry with a lithium 2,5-dihydroxybenzoate matrix. CHC profiles were obtained for 12 species of diverse insect taxa (termites, ants, a cockroach, and a flesh fly). MALDI spectra revealed the presence of high molecular weight CHCs on the insect cuticle. Hydrocarbons with more than 70 carbon atoms, both saturated and unsaturated, were detected. When compared with gas chromatography/mass spectrometry (GC/MS), MALDI-TOF covered a wider range of CHCs and enabled CHCs of considerably higher molecular weight to be detected. Good congruity between GC/MS and MALDI-TOF was observed in the overlapping region of molecular weights. Moreover, a number of previously undiscovered hydrocarbons were detected in the high mass range beyond the analytical capabilities of current GC/MS instruments. MALDI was shown to hold potential to become an alternative analytical method for insect CHC analyses. The ability of MALDI to discriminate among species varying in the degree of their relatedness was found to be similar to GC/MS. However, neither MALDI-MS nor GC/MS data were able to describe the phylogenetic relationships.
- MeSH
- chloroform chemie MeSH
- hmyz fyziologie MeSH
- spektrometrie hmotnostní - ionizace laserem za účasti matrice MeSH
- uhlovodíky analýza metabolismus MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- chloroform MeSH
- uhlovodíky MeSH
