Showing 1-25 of 25 results for "

135321

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A Ranz et al.
Journal of biochemical and biophysical methods, 69(1-2), 3-14 (2006-03-28)
In the present study, a derivatization method for the determination of acidic herbicides has been investigated. This procedure involves the methylation with the quaternary ammonium salt trimethylanilinium hydroxide (TMAH) directly in the gas chromatographic auto-sampler vial for analysis by gas...
Yasser El-Nahhal et al.
Journal of agricultural and food chemistry, 53(5), 1620-1624 (2005-03-03)
This study aimed to evaluate new methodology for designing ecologically acceptable formulations of acetochlor. Modification of montmorillonite with phenyltrimethylammonium chloride (PTMA) or benzyltrimethylammonium chloride (BTMA) and organoclay formulations of acetochlor were prepared in the presence of high concentrations of sodium...
Alec N Salt
Advances in oto-rhino-laryngology, 59, 140-148 (2002-03-12)
The inner ear fluids are remarkably 'unstirred' so that it cannot be assumed that applied drugs are dispersed throughout the fluid spaces. Calculation of the effective concentrations achieved when drugs are applied directly to the inner ear is made possible...
Robert Mynatt et al.
Journal of the Association for Research in Otolaryngology : JARO, 7(2), 182-193 (2006-05-24)
Local applications of drugs to the inner ear are increasingly being used to treat patients' inner ear disorders. Knowledge of the pharmacokinetics of drugs in the inner ear fluids is essential for a scientific basis for such treatments. When auditory...
Anthony A Mikulec et al.
Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology, 29(7), 1020-1026 (2008-09-02)
Intratympanic drug delivery has become widely used in the clinic, but little is known regarding how clinically used drug preparations affect round window membrane (RWM) permeability or how much drug is actually delivered to the cochlea. This study evaluated the...
A N Salt et al.
Hearing research, 154(1-2), 88-97 (2001-06-26)
The administration of drugs to the inner ear via the round window membrane is becoming more widely used for both clinical and experimental purposes. The actual drug levels achieved in different regions of the inner ear by this method have...
Cláudia Margalho et al.
Journal of analytical toxicology, 29(5), 309-313 (2005-08-18)
A simple and rapid method was validated to determine furosemide in whole blood. The experimental work was performed so that all validation parameters are considered simultaneously in a one-day assay protocol. A solid-phase extraction procedure using BondElut-LRC Certify columns was...
Timothy J Jensen et al.
Journal of photochemistry and photobiology. B, Biology, 100(2), 100-111 (2010-06-19)
Five cationic porphyrins bearing one to four -N(CH(3))(3)(+) groups linked to the p-phenyl positions of 5,10,15,20-tetraphenylporphyrin (TPP) were synthesized in order to study the effect of overall charge and its distribution on the cellular uptake, phototoxicity and intracellular localization using...
Marek Majdan et al.
Journal of environmental management, 91(1), 195-205 (2009-09-01)
The comparison of phenol sorption on phenyltrimethylammonium (PTMA)- and benzyltrimethylammonium (BTMA)-bentonite shows a clear difference as far as phenol sorption isotherms are concerned. For PTMA-bentonite the sorption isotherm is of a straight-line character which results from simple partitioning of phenol...
Jeanne Sirovatka Dorweiler et al.
Biochemistry, 42(49), 14653-14662 (2003-12-10)
Cobalamin-dependent methionine synthase (MetH) catalyzes the transfer of methyl groups between methyltetrahydrofolate (CH(3)-H(4)folate) and homocysteine, with the enzyme-bound cobalamin serving as an intermediary in the methyl transfers. An MetH fragment comprising residues 2-649 contains modules that bind and activate CH(3)-H(4)folate...
Vincenzo Rispoli et al.
Neuroscience letters, 356(3), 199-202 (2004-03-24)
The effects of two choline pivaloyl esters, [2-(2,2-dimethylpropionyloxy)ethyl]trimethylammonium iodide (1) and [2-(2,2-dimethylpropionyloxy)ethyl]trimethylammonium 2,2-dimethylpropionate (2), on learning and memory impairments induced in rats by scopolamine or lesions of nucleus basalis magnocellularis (NBM) have been evaluated by object recognition and Morris water...
D Monnaie et al.
Biochemistry, 39(18), 5349-5354 (2000-05-23)
In the process of characterizing the Na(+)-binding properties of factor Xa, a specific inhibition of this enzyme by quaternary amines was identified, consistent with previous observations. The binding occurs with K(i) in the low millimolar range, with trimethylphenylammonium (TMPA) showing...
Alec N Salt et al.
Hearing research, 182(1-2), 24-33 (2003-09-02)
Our understanding of the perilymph kinetics of drugs depends largely on data obtained by the analysis of perilymph samples. Although a number of studies have demonstrated qualitatively that perilymph samples may be contaminated by cerebrospinal fluid (CSF), and some investigations...
R W Gullick et al.
Environmental science & technology, 35(7), 1523-1530 (2001-05-12)
A natural shale and four synthetic organoclays were compared as potential sorbent additives to containment barriers at hazardous waste sites. Trimethylphenyl ammonium bentonite (TMPA-bent) was shown in batch experiments to have the greatest sorption capacities for 1,2,4-trichlorobenzene, trichloroethylene, and methyl...
Alec N Salt et al.
Hearing research, 232(1-2), 78-86 (2007-07-31)
Local delivery of drugs to the inner ear is increasingly being used in both clinical and experimental studies. Although direct injection of drugs into perilymph appears to be the most promising way of administering drugs quantitatively, no studies have yet...
Alec N Salt et al.
Journal of the Association for Research in Otolaryngology : JARO, 13(6), 771-783 (2012-09-13)
Perilymph pharmacokinetics was investigated by a novel approach, in which solutions containing drug or marker were injected from a pipette sealed into the perilymphatic space of the lateral semi-circular canal (LSCC). The cochlear aqueduct provides the outlet for fluid flow...
Anthony A Mikulec et al.
Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology, 30(2), 131-138 (2009-01-31)
Drugs applied to the middle ear enter perilymph through the bony otic capsule. Drugs applied intratympanically in humans are thought to enter the cochlea primarily through the round window membrane (RWM). Local drug treatments of the ear are commonly evaluated...
Jeffrey T Auletta et al.
Chemico-biological interactions, 187(1-3), 135-141 (2010-05-25)
Acetylcholinesterase (AChE) contains a narrow and deep active site gorge with two sites of ligand binding, an acylation site (or A-site) at the base of the gorge and a peripheral site (or P-site) near the gorge entrance. The P-site contributes...
Kanchanavadee Amphaisri et al.
Journal of chromatography. A, 1218(7), 972-980 (2011-01-11)
On-site verification of the chemical weapon convention (CWC) requires provision for the detection and identification of alkyl phosphonic acids as well as some organic acids that are amenable to GC-MS only after derivatisation. Various derivatisation methods have been used for...
Neera Singh
Journal of environmental science and health. Part. B, Pesticides, food contaminants, and agricultural wastes, 41(1), 17-29 (2006-01-06)
The study aims to prepare the organoclay complexes of metolachlor and metribuzin so as to reduce their downward mobility in soil profile. The organoclays were preadsorbed with phenyltrimethylammonium (PTMA) (50% of cation exchange capacity [CEC]) and hexadecyltrimethylammonium (HDTMA) (100% of...
Jie Zhang et al.
Journal of chromatography. A, 1216(44), 7527-7532 (2009-04-07)
A method has been established for the determination of four pharmaceutically active compounds (ibuprofen, ketoprofen, naproxen and clofibric acid) in water samples using dynamic hollow fiber liquid-phase microextraction (HF/LPME) followed by gas chromatography (GC) injection port derivatization and GC-mass spectrometric...
Y El-Nahhal et al.
Journal of agricultural and food chemistry, 48(10), 4791-4801 (2000-10-29)
This study aimed to design formulations of hydrophobic herbicides, alachlor and metolachlor, by adsorbing them on the clay mineral montmorillonite preadsorbed by the small organic cation phenyltrimethylammonium (PTMA). An adsorption model that considers electrostatics and specific binding and the possibility...
Petr Gebauer et al.
Electrophoresis, 29(5), 1067-1076 (2008-01-26)
In electrophoresis, the introduction of a sample into the BGE creates two new zone boundaries, the front and rear boundary of the sample zone which is sandwiched between the BGE. During an electrophoresis run, these boundaries move and split into...
Godfrey Lisk et al.
Molecular pharmacology, 71(5), 1241-1250 (2007-02-09)
Human red blood cells infected with the malaria parasite Plasmodium falciparum have markedly increased permeabilities to diverse organic and inorganic solutes. The plasmodial surface anion channel (PSAC), recently identified with electrophysiological methods, contributes to the uptake of many small solutes....
Alec N Salt et al.
Hearing research, 283(1-2), 14-23 (2011-12-20)
It has been widely believed that drug entry from the middle ear into perilymph occurs primarily via the round window (RW) membrane. Entry into scala vestibuli (SV) was thought to be dominated by local, inter-scala communication between scala tympani (ST)...