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PubMed1978

Ion exchange method for determining mephentermine sulfate in drug formulations: collaborative study.

Ion exchange chromatography is used to separate mephentermine sulfate from drug formulations. The drug is subsequently measured by ultraviolet spectrophotometry. Assays on 4 commercial samples of tablets and injectables gave recoveries from 97.6 to 104% of declared. A collaborative study involving 2 tablet and 2 liquid formulations gave mean recoveries ranging from 94.7 to 99.3% and coefficients of variation from 1.39 to 2.00%.

Chromatography, Ion Exchange↗
PubMed1981

Effect of diet on fecal excretion and gastrointestinal tract distribution of unmetabolized benzo(a)pyrene and 3- methylcholanthrene when these compounds are administered orally to hamsters.

3-Methylcholanthrene (3MC) administered p.o. has induced tumors of the hamster gastrointestinal tract (GIT), including the large intestine. This process may depend on the concentration of unchanged hydrocarbon in the GIT contents. Benzo(a)pyrene (BP) ingestion could be involved in human GIT carcinogenesis. Accordingly, male Syrian golden hamsters were fed diets containing BP or 3MC for 10 days. Feces collected during the last two to three days of feeding were analyzed for the unchanged hydrocarbons by KOH:methanol digestion, Florisil column and paper chromatography, and ultraviolet spectrophotometry. With a semisynthetic diet containing 5% Alphacel, 6% corn oil, and 100 microgram BP per g. fecal BP excretion was 0.45% of the dose. Variation of the corn oil content had little effect. Fecal BP excretion was increased 13 times (to 6% of the dose) when 5% wheat brain was used in place of Alphacel and 4.5 times when a commercial diet was used. This suggests that bran adsorbed or sequestered the BP. Water content of the large-intestine contents was increased when the brain diet was fed. Both these factors could affect mucosal exposure to BP. For 3MC, fecal excretion of unchanged hydrocarbon was 14 times greater than for BP under similar conditions. The GIT contents of hamsters fed BP or 3MC showed hydrocarbon concentrations in the order: stomach greater than lower large intestine greater than other sections.

Animals↗
PubMed1982

Isolation and identification of 25-hydroxyvitamin D3-26,23-peroxylactone. A novel in vivo metabolite of vitamin D3.

A new vitamin D3 metabolite was isolated in pure form (18.2 micrograms) from the serum of rats given large doses (two doses of 26 mumol/rat) of vitamin D3. The new metabolite has been unequivocally identified as 3 beta, 25-dihydroxy-9,10-seco-5,7,10(19)-cholestatrieno-26,23-peroxylactone by ultraviolet absorption spectrophotometry, Fourier transform infrared spectrophotometry, mass spectrometry, field desorption mass spectrometry, and specific chemical reaction with triphenyl phosphine. The stereochemical configuration at the C-23 and c-25 positions of the 25-hydroxyvitamin D3-26-23-peroxylactone was definitely determined to be the 23(S)25(R),25-hydroxyvitamin D3-26,23-peroxylactone is suggested for this metabolite. The isolation involved chloroform-methanol extraction and four column chromatographic procedures. The metabolite purification and elution position on these columns were followed by UV measurement at 264 nm. This metabolite was ultimately resolved from the previously known 25-hydroxyvitamin D3-26,23-lactone by high pressure liquid chromatography using a Zorbax Sil column. The 25-hydroxyvitamin D3-26,23-peroxylactone was converted upon storage at room temperature or -20 degrees C into the 25-hydroxyvitamin D3-26,23-lactone. Since under the conditions of this isolation only the 26,23-peroxylactone and no 26,23-lactone of 25-hydroxyvitamin D3 was present in the rat serum, this suggests that the 25-hydroxyvitamin D3-26,23-peroxylactone is the naturally occurring metabolite.

Animals↗
PubMed1984

Toxicologic studies in a fatal overdose of 2,4-D, mecoprop, and dicamba.

A suicidal poisoning committed by a 61-year-old woman, who ingested an unknown quantity of Killex, containing in aqueous solution 100 g/L of (2,4-dichlorophenox)acetic acid (2,4-D), 50 g/L of mecoprop, and 9 g/L of dicamba as amine salts is described. Quantitation of chlorophenoxy acids was performed by extraction from an acidified mixture and concentration before high performance liquid chromatography analysis. All three herbicides were separated in a phosphate buffer/acetonitrile mixture at 280 nm on a RP-8 column. Concentrations of herbicides found were: in blood--520-mg/L 2,4-D, 530-mg/L mecoprop, and 170-mg/L dicamba; in urine--670-mg/L 2,4-D and 520-mg/L mecoprop; in bile--340-mg/L 2,4-D, 530-mg/L mecoprop, and 140-mg/L dicamba; and in liver--540-mg/Kg 2,4-D, 500-mg/Kg mecoprop, and less than 100-mg/Kg dicamba. Liquid chromatography was found to be a reliable method for herbicide quantitation in biological tissues and fluids. The technique offered definite advantages over ultraviolet spectrophotometry and avoids the derivatization requirement for gas chromatography.

2,4-Dichlorophenoxyacetic Acid↗
PubMed1983

Spectrophotometric determination of hydralazine hydrochloride tablets using ninhydrin.

A method is described for the assay of hydralazine HCl in tablets, based on the colored product formed by the reaction between hydralazine and ninhydrin. The reaction is conducted at room temperature in a pH 3 buffer solution and the colored product is measured spectrophotometrically at the absorption maximum at 442 nm. Under the stipulated conditions, this reaction is highly specific for hydralazine and is not affected by other drugs which may be used in combination with hydralazine. Results of infrared and mass spectrometric studies suggested that the colored product is a hydrazone. Ultraviolet spectrophotometry also showed that dilute solutions of hydralazine degrade rapidly in the presence of alcohols.

Hydralazine↗
PubMed1981

Airborne drug levels in a laminar-flow hood.

The airborne levels of fluorouracil and cefazolin sodium injections after manipulation of these drug products inside a horizontal laminar-flow hood were measured. The Biotest RCS Centrifugal Air Sampler, generally used to measure microbial levels in air, was adapted with a paper filter to measure drug levels in air. In each of nine trials, five ampuls of fluorouracil were opened in the hood and transferred to empty vials. Likewise, in each of nine trials, 50 vials of cefazolin sodium 1 g were reconstituted and transferred to small-volume i.v. solutions. Drug manipulations were performed between the hood's filter and the Biotest, which was placed inside the hood. Drug collected on the filter in the Biotest was assayed with ultraviolet spectrophotometry after extraction. The range of fluorouracil collected by the Biotest was from 0 to 14 microgram, corresponding to 0-0.07 microgram/liter of sample air. Recovered cefazolin sodium ranged from 28 to 131 microgram, or 0.02-0.11 microgram/liter of sampled air. Following routine manipulation of drug products in a laminar-flow hood, the drug can contaminate, the air flowing over the product.

Air Pollutants↗
PubMed1978

[Effect of new technologies in the coke industry on aromatic polycyclic hydrocarbon concentrations in the ambient air].

Concentractions of aerosols, amount of polycyclic hydrocarbons, in terms of soluble in benzene fraction and benzo(a)pyrene concentration were determined in coking plant air. Air was sampled on the roofs of modern coke batteries and on old-type batteries prior to, and following, modernization and major reapir. Aerosols were determined by passing 10--100 m3 of air through a 26 X 18.5 cm filter. After a weight determination of aerosol content the filter was subjected to benzene extraction and aromatic polycyclic hydrocarbons were isolated from the extract, using thin-layer chromatography. Quantitative determination of these hydrocarbons was done using ultraviolet spectrophotometry. Results of determinations on work-posts in modern and old-type coke batteries prior to, and following, modernization were comapred. Average concentrations of aerosols in the air, amounts of polycyclic hydrocarbons soluble in benzene and concentration of benzo(a)pyrene determined on the roofs of old coke batteries before modernization were as follows: 11.26 mg/m3, 6.37 ug/m3 and 112.28 mg/m3, and after modernization: 0.88 mg/m3, 0.25 mg/m3 and 1.29 ug/m3, respectively. On the roofs of modern high chamber coke batteries average concentrations of aerosols, polycyclic hydrocarbons--benzo(a)pyrene amounts were: 4.21 mg/m3, 0.79 mg/m3 and 5.72 ug/m3, respectively. The results clearly demonstrate that work conditions in modernized coking plants are much better than those in old non-modernized coking plants.

Air Pollutants↗
PubMed1979

Improved determination of serum theophylline by gas chromatography with use of a nitrogen-phosphorus detector.

We describe a method for the 7-min determination of theophylline in less than 100 muL of serum. The procedure requires no centrifugation or solvent evaporation after extraction. Butylation is done on the gas-chromatographic column by injecting the serum extract followed by a butylating mixture which contains 1-iodobutane as the alkylating agent. The method is precise, accurate, and free of interference. Results correlate well with those by ultraviolet spectrophotometry.

Animals↗
PubMed1995

Rhodopsin from the fish, Astyanax: role of tyrosine 261 in the red shift.

PURPOSE: To isolate and characterize the rhodopsin cDNA from the fish, Astyanax fasciatus, and to determine the effect of tyrosine 261 on its spectral tuning. METHODS: The rhodopsin cDNA was cloned using reverse transcription-polymerase chain reaction amplification and then sequenced. A mutant, Y261F, was generated by site-directed mutagenesis. Both wild type and mutant were transiently expressed in COS-1 cells, regenerated with 11-cis retinal, and purified by immunoaffinity chromatography. Ultraviolet-visible spectrophotometry was used to determine wavelength of maximum absorption. RESULTS: A fasciatus rhodopsin cDNA exhibits 80% amino acid identity with bovine rhodopsin. In contrast to all known rhodopsins, this rhodopsin contains a tyrosine instead of a phenylalanine at amino acid position 261. Indeed, this particular amino acid replacement has been implicated in the long wavelength absorption of the red cone pigment. Site-directed mutagenesis was used to change the Astyanax amino acid 261 to phenylalanine (Y261F). Expression of the Y261F mutant in COS-1 cells showed an absorbance maximum of 496 nm, compared to 504 nm for the wild type pigment. CONCLUSIONS: A naturally occurring fish rhodopsin is red shifted about 8 nm due to one critical amino acid substitution.

Amino Acid Sequence↗
PubMed1977

Separation and ultraviolet absorbance techniques for determining dihydrotachysterol in pharmaceutical preparations.

Three separation techniques and ultraviolet (UV) spectrophotometry are described for dihydrotachysterol (DHT). The absorbance procedure eliminates the necessity of establishing a regular baseline, which is advantageous in certain cases. The relative absorbance values obey Beer's law in the range of 1-10 mug DHT/ml ethanol. An absorbance ratio check ensures the applicability of the method with respect to the degree of allowable interference present. The absorbance ratio values at the indicated wave-lengths at this concentration range and in the absence of any interferences are relativiely constant. The UV absorbance could serve as the common final determinative step for the other techniques, either singly or in combination, for quantitating DHT in preparations that require varying degrees of cleanup through extraction, saponification, and thin layer chromatography. The respective mean per cent recoveries and their relative standard deviations for a 50 mug DHT standard sample treated by the 3 techniques are 99.6 -+/ 0.5, 98.5 -+/ 1.1, and 97.3 -+/ 3.3%. Content uniformity determination of DHT in tablets and in soft gelatin capsules is also presented, and precautions are discussed.

Absorption↗
PubMed1995

[Excitation of hypothalamic nucleus arcuatus neuron induced decrease of plasma sialic acid level in rats].

The effect of sodium glutamate (Glu) on plasma sialic acid (SA) level was studied by means of microinjection into the nucleus arcuatus (ARC) and ultraviolet spectrophotometry. The results indicate: (1) The plasma SA level was significantly decreased after microinjection of Glu into the ARC (P < 0.01). With increasing Glu concentration, the onset of the decrease occurred earlier. (2) When Glu was microinjected into ARC after intraventricular injection of apomorphine, the plasma SA level was significantly decreased (P < 0.01) and the time required to cause the decrease was shortened. (3) When Glu was microinjected into ARC after intraventricular injection of spiperone, no change was found in the plasma SA level (P > 0.05). The above results suggest that the mechanism underlying the decrease of plasma SA level is probably related to modulated dopamine (DA) release of hypothalamic dopaminergic neurons by DA-D2 receptor.

Animals↗
PubMed1996

In vitro evaluation of polymeric matrix and porous biodegradable reservoir devices for slow-release drug delivery.

BACKGROUND AND OBJECTIVE: Biodegradable polymeric devices were evaluated in vitro for intravitreal drug delivery. MATERIALS AND METHODS: The matrix (short-term drug delivery) and the porous (longer-term drug delivery) reservoir devices were made from polycaprolactone of two molecular weights (30,000 and 56,000). Matrix devices were loaded with 5-fluorouracil or ganciclovir. Porous reservoirs were loaded with 5-fluorouracil, ganciclovir, 5-carboxyfluorescein, or foscarnet. The release was monitored in phosphate-buffered solution using ultraviolet spectrophotometry. RESULTS: Release from the matrix devices was characterized by an initial burst, followed by a nonlinear release. The porous reservoirs demonstrated zero order linear release of drugs, sustained up to 250 days in this experiment. CONCLUSIONS: The matrix device is capable of sustained release over several months; the porous reservoir can deliver drugs for over 1 year. Further studies are needed to evaluate in vivo biodegradation behavior and toxicity of drugs used for sustained release.

Antiviral Agents↗
PubMedDate not supplied

The metabolic fate of daidzein.

A method using thin layer chromatography and ultraviolet spectrophotometry for isolation and quantitative determination of daidzein from biological specimens was developed. This method was found to be sensitive and specific and was used in this study for the observation of the metabolic fate of daidzein in animals and human bodies.

Administration, Oral↗
PubMed1979

[On the presence of 20-methylcholanthrene in the atmospheric air (author's transl)].

The strongly carcinogenic polycyclic aromatic hydrocarbon 20-Methylcholanthrene was detected in the urban atmospheric air in Budapest (the capital of Hungary). The main source of this pollution seems to be the motor vehicle traffic, since samples from a heavy traffic junction contained up to six times higher 20-Methylcholanthrene concentrations than samples from a low traffic area. Ultraviolet absorption spectrophotometry yielded similar results. The presence of 20-Methylcholanthrene is apparently connected with the presence of 3,4-Benzpyrene and 1,2-Benzpyrene, respectively.

Air Pollution↗
PubMed1998

Differential effects of nitric oxide-mediated S-nitrosylation on p50 and c-jun DNA binding.

BACKGROUND: Nitric oxide (NO) regulates a variety of cellular functions. One mechanism by which NO may exert its influence is through formation of S-nitrosothiols at critical thiol residues in protein-active sites, including those of nuclear protein transcription factors. METHODS: NF-kappa B p50 and AP-1 c-jun were S-nitrosylated in the presence of acidic NaNO2. Wild-type protein and protein subjected to nitrosylating conditions in the absence of NaNO2 served as controls. Confirmatory evidence for S-nitrosothiol bond formation was obtained by ultraviolet-visible spectrophotometry with the absorption maximum for S-NO bonds at approximately 320 to 360 nm. With consensus oligonucleotide probes, gel-shift analysis was used to examine DNA binding characteristics. RESULTS: In the case of NF-kappa B p50, S-nitrosylation resulted in significantly decreased DNA binding. In contrast, S-nitrosylation did not alter c-jun DNA binding. The S-nitrosylating conditions themselves did not alter p50 or c-jun DNA binding. Quantitative analysis was performed according to the Scatchard plot technique to generate the respective dissociation constants. S-nitrosylated p50 was associated with a fourfold greater dissociation constant than that of the wild-type p50. CONCLUSIONS: S-nitrosylation of transcription factors may be one mechanism by which NO may selectively regulate gene transcription.

Carcinogens↗
PubMed2001

Egg colour matching in an African cuckoo, as revealed by ultraviolet-visible reflectance spectrophotometry.

Despite major differences between human and avian colour vision, previous studies of cuckoo egg mimicry have used human colour vision (or standards based thereon) to assess colour matching. Using ultraviolet-visible reflectance spectrophotometry (300-700 nm), we measured museum collections of eggs of the red-chested cuckoo and its hosts. The first three principal components explained more than 99% of the variance in spectra, and measures of cuckoo host egg similarity derived from these transformations were compared with measures of cuckoo host egg similarity estimated by human observers unaware of the hypotheses we were testing. Monte Carlo methods were used to simulate laying of cuckoo eggs at random in nests. Results showed that host and cuckoo eggs were very highly matched for an ultraviolet versus greenness component, which was not detected by humans. Furthermore, whereas cuckoo and host were dissimilar in achromatic brightness, humans did not detect this difference. Our study thus reveals aspects of cuckoo-host egg colour matching which have hitherto not been described. These results suggest subtleties and complexities in the evolution of host-cuckoo egg mimicry that were not previously suspected. Our results also have the potential to explain the longstanding paradox that some host species accept cuckoo eggs that are non-mimetic to the human eye.

Animals↗
PubMed2004

Vacuum-ultraviolet circular dichroism study of saccharides by synchrotron radiation spectrophotometry.

Vacuum-ultraviolet circular dichroism (VUVCD) spectra of five monosaccharides (D-glucose, D-mannose, D-galactose, D-xylose, and D-lyxose) and five disaccharides (maltose, isomaltose, cellobiose, gentiobiose, and lactose) were measured to 160 nm using a synchrotron-radiation VUVCD spectrophotometer in aqueous solution under high vacuum at 25 degrees C. Most of the saccharides show a positive peak with some shoulders at around 170 nm, except for D-galactose and lactose, which show two distinct negative peaks at around 165 and 177 nm. These spectra are influenced by such structural factors as alpha and beta anomers at C-1, axial and equatorial hydroxyl groups at C-2 and C-4, trans (T) and gauche (G) conformations of the hydroxymethyl group at C-5, and the type of glycosidic linkage. Deconvolution of the VUVCD spectra of D-glucose, D-mannose, and D-galactose into six independent Gaussian components for alpha-GG, alpha-GT, alpha-TG, beta-GG, beta-GT, and beta-TG conformations suggests that the alpha anomer has red-shifted spectra relative to the beta anomer, and that GG and GT conformations have positive and negative circular dichroism signs, respectively, while the sign for TG conformation is anomer dependent. These speculations from the deconvolution analyses are also supported by the VUVCD spectra of disaccharides. These results give new insight into the equilibrium conformations of saccharides, demonstrating the usefulness of synchrotron-radiation VUVCD spectroscopy.

Carbohydrate Conformation↗