Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016382 (flushing)
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Acid/base titrations of pico- and femtoliter microsamples have been performed previously using a diffusional microburet (DMB) for reagent delivery in a simple droplet-heptane system (Gratzl, M.; Yi, C. Anal. Chem. 1993, 65, 2085-2088). The lowest delivery rate achieved with a DMB was about 6 fmol/s, which would correspond to about a 1 microL/year volumetric flow rate with a hypothetical equivalent mechanical delivery scheme (Yi, C.; Gratzl, M. Anal. Chem. 1994, 66, 1976-1982). In this work, the feasibility of complexometric titrations in microscopic samples is explored. Stability of pH in the microdroplets required for different determinations and the effects of DMB shank geometry on titration characteristics are also studied. Diffusional microtitrations of Fe(III), Zn(II), and Cu(II) have been performed with EDTA. Xylenol orange and Eriochrome Black T provide clear color changes at the end point of the respective titrations, despite the microscopic size of the samples (between 16 and 1570 pL, corresponding to diameters between 30 and 144 microns). Random errors of the determinations relative to full scale were 6.6% for Fe(III), 5.8% for Cu(II), and 7.9% for Zn(II). The pH required for EDTA titrations of the individual metal ions stays stable in the acidic range. This makes the microscopic titration of a number of metal ions, such as Fe(III), Fe(II), Cu(II), and Pb(II), feasible in a simple droplet-heptane system without any modification. With a higher density of strongly alkaline buffer droplets (about 100 droplets/mm2) sprayed on the bottom of the Petri dish, or by flushing N2 above the heptane, the microscopic samples can also be kept alkaline despite ambient CO2 present. In this way, Zn(II) can also be titrated in microdroplets, requiring a pH around 10. This work renders it possible to perform a variety of complexometric titrations and other chemical manipulations in microdroplets even if they need to be kept alkaline. Similar titrations in single biological cells to assess intracellular buffer capacities of different metal ions, such as Ca(II) and Mg(II), are underway.
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PMID:Complexometric determination of metal ions by microscopic diffusional titration. 881 47

The drug sildenafil (Viagra, Pfizer) and, more recently, tadalafil (Cialis, Lilly-Icos) and vardenafil (Levitra, Bayer), has drawn public attention to aphrodisiacs. The search for such substances dates back millennia. Adverse effects associated with these drugs include hypotension, tachycardia, headache, flushing, blurred vision, dyspepsia, and musculoskeletal pain. Although sildenafil has been marketed for erection of the penis, recent attention has been paid to its application for women, including enhancement of success of in vitro fertilization but also better sexual responses (increased desire, satisfaction, and orgasm) in cases of sexual disorders. Today, there is a debate on internet forums about the potential properties of sildenafil to enhance women's sexual pleasure. This laboratory was asked to analyze a 12-cm length of light brown hair submitted by a British police force following an allegation that a young female had been subjected to sexual assaults over a two-year period. The female was 15-17 years of age at the time. The alleged perpetrator was her stepfather, and there was some suspicion that drugs may have been administered to facilitate the attacks. After decontamination and segmentation (6 x 2-cm section), the specimen was analyzed by liquid chromatography coupled with tandem mass spectrometry after alkaline (pH 9.5) extraction using dichloromethane/ isopropanol/n-heptane (25:10:65, v/v/v). The limit of quantitation was 5 pg/mg. The proximal segment tested positive for sildenafil at 38 pg/mg, and all others proved negative. This was in accord with the victim's claim. In the absence of any controlled studies, it was impossible to put any quantitative interpretation on the measured concentration.
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PMID:Hair analysis to demonstrate administration of sildenafil to a woman in a case of drug-facilitated sexual assault. 1987 68

This study investigates the synthesis and chromatographic behaviour of an analytical size cyanopropyl "cyano" bonded silica monolith. Surface modification was undertaken by treating a neat silica monolith with chloro(3-cyanopropyl)dimethyl silane in dry heptane over a two day period. The resulting monolith showed stability over the duration of the testing program that involved flushing the column with more than 2000 column volumes of mobile phase. Efficiency measurements before and after sylation verified that the integrity of the silica monolith itself was not affected by the modification process, the highest number of theoretical plates (N/m) using anisole was 81,650. A brief selectivity test was then undertaken to assess methylene selectivity and phenyl selectivity. Elemental analysis was used to determine the homogeneity of the carbon load throughout the monolithic bed, and was compared to two commercial C18 and one 'self' modified C18 silica monoliths. The development of the in situ modification is also discussed.
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PMID:Cyano bonded silica monolith--development of an in situ modification method for analytical scale columns. 2073 87

A dicationic ruthenium-alkylidene complex [Ru(dmf)(3)(IMesH(2))(=CH-2-(2-PrO)-C(6)H(4))][(BF(4))(2)] (1; IMesH(2) =1,3-dimesitylimidazolin-2-ylidene) has been prepared and used in continuous metathesis reactions by exploiting supported ionic-liquid phase (SILP) technology. For these purposes, ring-opening metathesis polymerization (ROMP)-derived monoliths were prepared from norborn-2-ene, tris(norborn-5-ene-2-ylmethyloxy)methylsilane, and [RuCl(2)(PCy(3))(2)(CHPh)] (Cy=cyclohexyl) in the presence of 2-propanol and toluene and surface grafted with norborn-5-en-2-ylmethyl-N,N,N-trimethylammonium tetrafluoroborate ([NBE-CH(2)-NMe(3)][BF(4)]). Subsequent immobilization of the ionic liquid (IL), 1-butyl-2,3-dimethylimidazolium tetrafluoroborate ([BDMIM][BF(4)]), containing ionic catalyst 1 created the SILP catalyst. The use of a second liquid transport phase, which contained the substrate and was immiscible with the IL, allowed continuous metathesis reactions to be realized. High turnover numbers (TONs) of up to 3700 obtained in organic solvents for the ring-closing metathesis (RCM) of, for example, N,N-diallyltrifluoroacetamide, diethyl diallylmalonate, diethyl di(methallyl)malonate, tert-butyl-N,N-diallylcarbamate, N,N-diallylacetamide, diphenyldiallylsilane, and 1,7-octadiene, as well as in the self-metathesis of methyl oleate, could be further increased by using biphasic conditions with [BDMIM][BF(4)]/heptane. Under continuous SILP conditions, TONs up to 900 were observed. Due to the ionic character of the initiator, catalyst leaching into the transport phase was very low (<0.1 %). Finally, the IL can, together with decomposed catalyst, be removed from the monolithic support by flushing with methanol. Upon reloading with [BDMIM][BF(4)]/1, the recycled support material again qualified for utilization in continuous metathesis reactions.
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PMID:A dicationic ruthenium alkylidene complex for continuous biphasic metathesis using monolith-supported ionic liquids. 2299 38