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At least 433 records · Page 24Linked to original sources

Permeation of cytotoxic formulations through swatches from selected medical gloves.

The permeability of selected medical glove materials to various cytotoxic agents is described. Fifteen cytotoxic agents were prepared at the highest concentrations normally encountered by hospital personnel. Four single-layer and two double-layer glove systems made of two materials--latex and neoprene--were exposed to the drugs for 30, 60, 90, 120, 150, and 180 minutes. Circular sections of the glove material were cut from the cuff and evaluated without any pretreatment. Permeability tests were conducted in an apparatus consisting of a donor chamber containing the cytotoxic solution and a collection chamber filled with water (the acceptor medium). The two sections were separated by the glove material. Permeating portions, collected in water as the acceptor medium, were analyzed by either ultraviolet-visible light spectrophotometry or high-performance liquid chromatography (HPLC). Permeation rates were calculated on the basis of the concentration of the cytotoxic agent in the acceptor medium. Spectrophotometric measurements were taken every 30 minutes, and HPLC analysis was performed at the end of the three-hour period. Average permeation rates for 14 drugs were low (< 0.2 nmol/[min.cm2]) or no permeation was detected in all glove materials. All glove materials tested were impermeable to most of the cytotoxic agents over a period of three hours. Carmustine was the only agent that substantially permeated single-layer latex glove materials. Permeation of most tested cytotoxic formulations was low through swatches of material from various medical gloves.

Carcinogens↗

On the chemical structure of menaquinones with the tetrahydrogenated isoprenoid side chain.

New menaquinones have been isolated from Oerskovia turbata and Brevibacterium lipolyticum in the nocardioform and coryneform groups of bacteria, which have been identified to be a series of menaquinones with a tetrahydrogenated isoprenoid chain, designated as menaquinone-9(H4) and menaquinone-8(H4), respectively, by thin layer chromatography, ultraviolet and infrared spectrophotometry and mass spectrometry. The nuclear magnetic resonance spectra of the quinones have revealed that all the two saturated dolble bonds occur in the internal units of the isoprenoid side chain.

Brevibacterium↗

Liquid-chromatographic determination of antidysrhythmic drugs: procainamide, lidocaine, quinidine, disopyramide, and propranolol.

We present a method for the analysis of antidysrhythmic drugs [procainamide, acecainide (NAPA), lidocaine, quinidine, disopyramide, N-desisopropyl disopyramide, and propranolol] in serum. The drugs, together with an internal standard, are extracted from 0.2-1.0 ml of serum, separated on an octyl-bonded reversed-phase column using a mobile phase consisting of acetonitrile/phosphate buffer, and monitored by either ultraviolet or fluorescence spectrophotometry. The proposed method offers good reproducibility, sensitivity, linearity, and accuracy. Of more than 50 drugs and metabolites, tested for possible interference, only diazepam, flurazepam, and the N-oxide metabolite of quinidine interfere with quinidine analysis, while meperidine coelutes with disopyramide. However, diazepam and flurazepam do not interfere with quinidine analysis with fluorescence detection.

Anti-Arrhythmia Agents↗

Do human tears absorb ultraviolet light?

We analyzed human tears by ultraviolet (UV) spectrophotometry for transmittance of UV light. Ultraviolet light was readily transmitted through human tears in the UV-A (320-400 nm) and UV-B (290-320 nm) ranges. Tears partially absorbed UV light in the UV-C (100-290 nm) range. The clinical implications of these findings include prevention of phototoxic ocular damage and effects upon excimer laser corneal photoablative techniques.

Absorption↗

Interaction of palladium (II) with DNA.

The nature of interaction of palladium (II) with calf thymus DNA was studied using viscometry, ultraviolet, visible and infrared spectrophotometry and optical rotatory disperison and circular dichroism measurements. The results indicate that Pd(II) interacts with both the phosphate and bases of DNA. The ORD/CD data indicate that the binding of Pd(II) to DNA brings about considerable conformational changes in DNA.

Animals↗

Evaluation of a second derivative UV/visible spectroscopy technique for nitrate and total nitrogen analysis of wastewater samples.

A method for nitrate analysis based on second derivative UV/Visible spectroscopy was developed by Simal et al. (1985: Simal J., Lage M. A., and Iglesias I. (1985) Second derivative ultraviolet spectroscopy and sulfamic acid method for determination of nitrates in water. J. Assoc. Analyt. Chem. 68, 962-964) and Suzuki and Kuroda (1987: Suzuki, N. and Kuroda R. (1987) Direct simultaneous determination of nitrate and nitrite by ultraviolet second-derivative spectrophotometry. Analyst 112, 1077-1079), and later modified for the analysis of total nitrogen in aqueous samples of varying nitrate:organic nitrogen ratios (Crumpton et al., 1992: Crumption W. G., Isenhart T. M. and Mitchell P. D. (1992) Nitrate and organic N analyses with second-derivative spectroscopy. Limnol. Oceanogr. 37, 907-913). The procedure uses the second derivative of the absorption spectrum for nitrate (NO3-), which has a peak at approximately 224 nm that is proportional to the NO3- concentration. Samples for total N analysis are first oxidized to NO3- by persulfate digestion. The objectives of this study were to: (1) test the accuracy and precision of the second derivative method through the use of NIST-traceable wastewater check samples; (2) determine whether the second derivative method for nitrate analysis can be used for wastewater samples and whether the method compares favorably with other currently used nitrate analysis methods; and (3) use the method to analyze wastewater samples containing a range of nitrate and total nitrogen concentrations. Our results indicated that the method needed to be modified to include a longer digestion time (60 min) and dilution of samples prior to digestion (if needed). With the modified method, nitrogen recoveries were not significantly different (P > or = 0.05) from samples with known N concentrations. In addition, nitrate concentrations in constructed wetland and wastewater samples analyzed by both second derivative spectroscopy and ion chromatography were not significantly different. Total nitrogen concentrations in wastewater samples also compared favorably to the same samples analyzed by Kjeldahl digestion. The method is faster, simpler, requires smaller sample volumes, and generates less waste than many EPA-approved methods of N analysis, and may offer a suitable alternative to current methods for analysis of nitrate and total N in wastewater samples.

Chromatography, Ion Exchange↗

23,25-Dihydroxy-24-oxovitamin D3: a metabolite of vitamin D3 made in the kidney.

Kidney homogenates of rats produced a new metabolite of 25-hydroxyvitamin D3 which has been isolated in pure form after five column chromatographic steps. It was identified as 23,25-dihydroxy-24-oxovitamin D3 by means of ultraviolet and infrared absorption spectrophotometry, mass spectrometry, and proton nuclear magnetic resonance spectrometry. The stereochemistry at the C-23 position is as yet unknown. 25-Hydroxy-24-oxovitamin D3, which also has been isolated in pure form from this system, was found to be the precursor of the new metabolite in vitro. The production of the new metabolite was induced by two different methods: (a) perfusion of the kidneys with 1,25-dihydroxyvitamin D3 contained in the perfusate and (b) injection of 1,25-dihydroxyvitamin D3 in the intact animal. 23,25-Dihydroxy-24-oxovitamin D3 was not biologically active in an assay for intestinal calcium transport and bone calcium mobilization in the vitamin D deficient chick at a dose level of 5.3 nmol. A metabolic pathway is proposed to describe the results; it leads from 25-hydroxyvitamin D3 leads to 24(R),25-dihydroxyvitamin D3 leads to 25-hydroxy-24-oxovitamin D3 leads to 23,25-dihydroxy-24-oxovitamin D3.

Animals↗

Identification of 1,25-dihydroxycholecalciferol, a form of vitamin D3 metabolically active in the intestine.

A biologically active vitamin D(3) metabolite ("peak V metabolite") more polar than 25-hydroxycholecalciferol has been isolated from chicken intestines in pure form as a mono(trimethylsilyl)ether derivative. The molecule has been identified as 1,25-dihydroxycholecalciferol by means of mass spectrometry, ultraviolet absorption spectrophotometry, and specific chemical reactions.

Animals↗

Refolding of the immunoglobulin light chain.

The kinetics of the refolding reactions of type lambda Bence Jones proteins from 4 M GuHCl were studied by CD, ultraviolet absorption, and fluorescence spectrophotometry. The kinetics were complex and consisted of at least three phases, an undetectable fast phase, a detectable fast phase, and a slow phase. The slow phase followed first-order kinetics and the three experimental methods used gave similar rate constants for all the Bence Jones proteins (about 3 X 10(-3) s-1). The refolding reaction of VL fragment was too fast to be measured in the present experiments. The refolding process of CL fragment was very similar to those of Bence Jones proteins except that the detectable fast phase was less significant. The rate constant of the slow phase observed for the CL fragment was similar to those of the slow phase observed for Bence Jones proteins. The activation energy of the slow phase was the same for a Bence Jones protein and its CL fragment. These results indicate that the refolding kinetics of the CL domain are very similar to those of isolated CL fragment and that refolding of the VL domain precedes refolding of the CL domain, even though both domains have similar immunoglobulin folds. However, the results of refolding experiments on Bence Jones proteins, and VL and CL fragments in the presence of ANS, as well as the other lines of evidence, indicate that the refolding kinetics of the Bence Jones protein molecule cannot be expressed as simple sum of the refolding reactions of isolated VL and CL fragments.

Bence Jones Protein↗

Influence of contact lens material surface characteristics and replacement frequency on protein and lipid deposition.

The aim of the study was to quantify the influence of both contact lens material and replacement frequency on protein and lipid deposition. The following hypotheses were tested: (1) both protein and lipid interaction with contact lenses are material-dependent, and (2) the key factors are the material ionicity for the protein deposition and the material chemical composition for the lipid deposition. Three high water content contact lens materials were tested: netrafilcon A (FDA group II, Gentle Touch), etafilcon A (FDA group IV, Acuvue), and vifilcon A (FDA group IV, Focus). Contact lens spoilation was analyzed using ultraviolet spectroscopy and fluorescence spectrophotometry. The results showed that (1) significantly more proteins were deposited on the ionic materials than on the nonionic materials, and that among the ionic materials, the higher the ionicity, the higher the level of protein deposition; (2) there were significantly more surface proteins on the ionic materials after 3 months than after 1 month of wear, but no difference over time was demonstrated for the nonionic materials; and (3) significantly more lipids were deposited onto the surface of vifilcon A than etafilcon A or netrafilcon A, and the presence of vinylpyrrolidone in the vifilcon A formulation was thought to be the cause of increased deposition. The protein and lipid interactions with contact lenses were found to be material- and time-dependent. Protein attraction was found to be related to the material ionicity. The presence of vinylpyrrolidone was a key factor in the attraction of lipids.

Contact Lenses, Hydrophilic↗

Production of fumigaclavine A by Aspergillus tamarii Kita.

Aspergillus tamarii Kita. isolated from seeds of Paspalum scrobiculatum L. is found to produce ergot alkaloids in submerged culture. The culture filtrate and mycelium are observed to contain 0.125 mg/mL and 1.2 mg/g (dry weight) total alkaloids consisting of 86.5 and 91.3% fumigaclavine A, respectively. The identification of the compound was confirmed by high-performance liquid chromatography, ultraviolet, infrared, and mass spectrophotometry analyses. This is the first report of the production of ergot alkaloid by this fungus. The possible role of fumigaclavine A as a mycotoxin is discussed.

Aspergillus↗