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PubMed1968

Estimation of cerebrospinal fluid protein.

Three turbidometric methods and one method using ultraviolet spectrophotometry for estimating total cerebrospinal fluid protein have been examined. The necessity for preliminary dialysis renders the ultraviolet method unsuitable for routine use. The turbidometric method of Meulemans (1960) using a sulphosalicylic acid-sodium sulphate precipitating fluid is better than a method using sulphosalicylic acid alone which is affected by the albumin-globulin ratio, and has a greater sensitivity and better reproducibility than a method using trichloracetic acid as a precipitant. Turbidity may be measured with a spectrophotometer or an MRC grey wedge photometer with human or bovine albumin as a standard. This method deserves wider acceptance.

Cerebrospinal Fluid Proteins↗

PubMed1992

Stable superoxide dismutase (SOD)-mimetic ternary human serum albumin-Cu(II)(3,5-diisopropylsalicylate)2/Cu(II)2(3,5-diisopropylsalicylate)4 complexes in tissue distribution of the binary complex.

Copper(II)2(3,5-diisopropylsalicylate)4 [Cu(II)2(3,5-DIPS)4] has been found to have antiinflammatory, antiulcer, anticancer, anticonvulsant, antimutagenic, antidiabetic, analgesic, and radiation protection and recovery activities. It has also been found to reduce ischemia-reperfusion injury. Because of these activities it was of interest to understand how this compound is transported in the body to affected tissues. Evidence supporting the suggested formation of ternary human serum albumin (HSA)-Cu(II)(3,5-DIPS)2 or Cu(II)2(3,5-DIPS)4 complexes was obtained using ultraviolet spectrophotometry, dialysis, and atomic absorption spectrophotometry or atomic emission spectroscopy. Superoxide dismutase (SOD)-mimetic activity was also determined using the xanthine/xanthine oxidase/cytochrome c system. Ultraviolet spectra of aqueous solution mixtures of Cu(II)2(3,5-DIPS)4 in equilibrium with 2Cu(II)(3,5-DIPS)2 and HSA as well as aqueous solutions of solid Cu(II)2(3,5-DIPS)4 obtained by stirring the solid with an aqueous solution of HSA showed no obvious change in absorbance to indicate ternary complex formation. However, comparison of ultraviolet spectra taken before and after dialysis supports the suggested bonding of Cu(II)(3,5-DIPS)2 or Cu(II)2(3,5-DIPS)4 to HSA. Comparison of copper concentrations before and after dialysis also supports the suggested bonding of Cu(II)(3,5-DIPS)2 or Cu(II)2(3,5-DIPS)4 to HSA. Based upon these data it is plausible that Cu(II)(3,5-DIPS)2 or Cu(II)2(3,5-DIPS)4 form stable ternary complexes with HSA. These stable ternary complexes were also found to have SOD-mimetic activity.

Copper↗

PubMed2003

[Derivation absorption spectrophotometry in the ultraviolet range as an alternative to HPLC and other instrumental methods of drug analysis].

A comparison of the results obtained by derivation absorption spectrophotometry in the ultraviolet region and those obtained by HPLC and other instrumental methods of quantitative analysis of drugs reveals that derivation spectrophotometry can be an economically advantageous alternative in many cases. The results of the determination of one drug on an interfering background or of two substances beside one another are usually comparable; for the evaluation of the determination of three or more substances enough data are not available.

Chromatography, High Pressure Liquid↗

PubMed2000

[The determination of ofloxacin by fluorescence spectrophotometry].

This paper reports the assay of ofloxacin by fluorescence spectrophotometry. The fluorescence strength of ofloxacin is proportional to its concentration within the range from 0.500-25.0 ppm. The linear regression coefficient equals to 0.9999, and the recovery ratio is 99.0%. The results of determination for the samples of ofloxacin capsule from China and Japan are very close to that determined by the ultraviolet spectrophotometry, there isn't any obviously difference which was examined by Student's test. This method is both simplicity and accuracy, also it needs only one kind of reagent. It's believable that this method would be suitable for the use in clinical medicine and pharmaceutical industry.

Anti-Infective Agents↗

PubMed1983

Formation of fatty acid esterified vitamin D3 in rat skin by exposure to ultraviolet radiation.

The formation of fatty acid esters of vitamin D3 was demonstrated in rat skin exposed to artificial ultraviolet rays by using multi-dimensional high-performance liquid chromatography, ultraviolet spectrophotometry, and gas-liquid chromatography-mass spectrometry. This result indicated that the fatty acid esters of 7-dehydrocholesterol in rat skin (at least 80% of 7-dehydrocholesterol in rat skin is esterified) is also isomerized into vitamin D3 ester in vivo. The initial percentage of the esterified form was 84.3% and this did not significantly change up to the time when about half of the skin total vitamin D3 disappeared (2 days). Consequently, it was speculated that the vitamin D3 ester was delivered into the blood circulation from skin without having been hydrolyzed. This was supported by the presence of vitamin D3 ester in rat plasma exposed to ultraviolet radiation. In addition, in connection with the study of the restriction of vitamin D3 synthesis, distribution of total vitamin D3 in rat skin exposed to ultraviolet irradiation in vivo was compared with that in isolated skin exposed to ultraviolet radiation. The dermal layer of the isolated skin contained about 4 times more total vitamin D3 than that of in vivo skin. This finding suggests not only that ultraviolet rays could not penetrate deeply into the in vivo skin, but that the restriction of cutaneous synthesis of vitamin D3 observed in vivo may arise from this reduced penetration of ultraviolet rays.

Animals↗

PubMed1975

Heavy metal-nucleotide interactions. III. The participation of amino groups in the binding of methylmercury (II) to cytidine and adenosine 5'-phosphate in aqueous solution: studies by Raman difference spectrophotometry.

Raman difference spectrophotometry has been used to study the interaction of CH3Hg(II) with cytidine and Ado-5'-P at high pH. In contrast to the binding reactions which occur at lower pH or in non-aqueous solvents such as dimethyl sulfoxide, a proton is transferred from the amino group; and the complexes are CH3HgCydH-1 and CH3HgAdoH-1-5'-P. The spectra are significantly different from those of the cationic complexes. The integrated intensities of ligand modes which shift upon metalation can be used to measure the concentration of unreacted ligand and consequently the extent of the reaction. Equilibrium constants for the reactions CH3HgOH + L yields CH3HgLH-1 + H2O were estimated to be log KCyd equals 0.63 plus or minus 0.05 and log KAdo-5'-P equals 0.85 plus or minus 0.05, in fair agreement with values determined under very different conditions by ultraviolet spectrophotometry. The vibrational spectrum of the ligand in CH3HgCydH-1 is virtually the same as that of UrdH-1- which is isoelectronic. The spectrum of the ligand in CH3HgAdoH-1-5'-P is more similar to the isoelectronic base InoH-1-than to Ado-5'-P, although the resemblance is not so close as in the CydH-1---UrdH-1-case. The structures of these complexes are discussed on the basis of their vibrational spectra and similarities in the spectra of related compounds. It is concluded that the CH3Hg(II) binds to the amino nitrogen at high pH with both cytidine and Ado-5'-P. In neutral solution with excess CH3Hg(II), metalation occurs on the amino groups, on the ring, and also on the ribose.

Adenosine Monophosphate↗

PubMed1995

DNA condensation by cobalt hexaammine (III) in alcohol-water mixtures: dielectric constant and other solvent effects.

DNA molecules condense into compact structures in the presence of a critical concentration of multivalent cations. To probe the contribution of electrostatic forces to condensation, we used mixtures of water with methanol (MeOH), ethanol (EtOH), and isopropanol (iPrOH) to vary the dielectric constant epsilon from 80 to 50. The condensation of pUC18 plasmids by hexaammine cobalt (III), Co(NH3)(3+)6, was monitored by total intensity and dynamic light scattering, electron microscopy, and CD. The total scattering intensity increased as epsilon went from 80 to 70, and the decreased as epsilon decreased further. Ultraviolet spectrophotometry confirmed that the loss of intensity at low epsilon was not due to the particles' settling out of solution. The rate as well as the extent of condensation increased as epsilon was lowered from 80 to 70, and also depended on the species of alcohol (MeOH < EtOH < iPrOH). The hydrodynamic radii RH of the particles, however, remained roughly the same at 300-350 A and was independent of the species of alcohol. RH increased below epsilon = 70. The critical concentration of Co(NH3)6(3+) required to induce DNA condensation decreased from 21 microM to about 16 microM as the dielectric constant decreased from 80 to 70, and decreased moderately with the nonpolarity of the alcohol. The fraction of DNA charge neutralized at the onset of DNA condensation was calculated by a modification of Manning's two-variable counterion condensation theory to be 0.90 +/- 0.01, independent of epsilon. By electron microscopy we observed that the condensed particles changed from about 93% toroids at epsilon = 80 to 89% rods at epsilon = 70 and 98% rods at epsilon = 65. At epsilon lower than 65, DNA collapsed into a network of multistranded fibers. The morphology of condensed DNA particles, whether toroids, rods, or fibers, was independent of the alcohol species. CD spectra in ethanol-water mixtures indicated that both closed circular and linearized plasmids were in the B conformation when condensed with Co(NH3)6(3+) at epsilon > or = 70, although the closed circular molecules exhibited a weak psi-DNA spectrum. A transition from the B to A form took place between epsilon = 70 and 60, well above the normal dielectric constant of epsilon = 40 for this transition, indicating that ethanol and Co(NH3)6(3+) synergistically promote the B-A transition. We interpret these results to mean that alcohols have both electrostatic and structural effects on DNA, leading to three regimes of condensation. At the lowest alcohol concentrations the B conformation is stable and condensation is relatively slow, allowing time for the packing adjustments necessary to form toroids.(ABSTRACT TRUNCATED AT 400 WORDS)

1-Propanol↗

PubMed1987

Reduction of quinones with zinc metal in the presence of zinc ions: application of post-column reactor for the fluorometric detection of vitamin K compounds.

A simple and effective chemical method has been developed for quantitatively reducing quinones, which is based on their reaction with zinc metal and zinc ions. Comparison of this method with conventional electrochemical reduction revealed the chemical method to be considerably superior. The reduction of quinones to their corresponding hydroquinones was verified by ultraviolet spectrophotometry. The reduction methodology has been applied to derivatize phylloquinone and its metabolite, namely phylloquinone 2,3-epoxide, 'on-line', with subsequent fluorometric detection of the generated hydroquinones.

Chromatography, High Pressure Liquid↗

PubMed1996

Ascitic fluid adenosine deaminase insensitivity in detecting tuberculous peritonitis in the United States.

Tuberculous peritonitis, although common in Third World countries, remains an uncommon cause of ascites in the United States. Ascitic fluid adenosine deaminase (ADA) activity has been proposed as a useful diagnostic test. The aim of this retrospective study was to determine the clinical utility of ascitic fluid ADA activity in diagnosing tuberculous peritonitis in a U.S. patient population. A total of 368 ascitic fluid specimens from a well-characterized ascitic fluid bank, including tuberculous peritonitis (n = 7), tuberculous peritonitis in the setting of cirrhosis (n = 10), and consecutive specimens of widely varied etiologies (n = 351) were analyzed for ADA activity by ultraviolet spectrophotometry at 265 nm. The overall sensitivity of the ADA determination in diagnosing tuberculous peritonitis was only 58.8%, and the specificity was 95.4%. The accuracy of ADA determination (93.8%) compared favorably with that of the common ascitic fluid tests of white blood cell (WBC) count (>500/mm3), total protein (>2.5 g/dL), and combined WBC count and total protein (45.8%, 74.4%, and 81.3%, respectively). However, ADA was only 30% sensitive in detecting tuberculous peritonitis in the setting of cirrhosis, and cirrhosis was present in 59% of the tuberculous peritonitis patients in our population. In addition, malignancy-related ascites (13%) and bacterial peritonitis specimens (5.8%) occasionally yielded false-positive results. In conclusion, our results indicate that the ascitic fluid ADA activity has good accuracy but poor sensitivity and imperfect specificity in a U.S. patient population in which the prevalence of tuberculosis is low and underlying cirrhosis is common.

Adenosine Deaminase↗

PubMed2002

Topical formulation studies with DEET (N,N-diethyl-3-methylbenzamide) and cyclodextrins.

The purpose of this study was to investigate the utility of cyclodextrins as a safer alternative to the commonly used cosolvent ethanol in topical N,N-diethyl-3-methylbenzamide (DEET) formulations. Ethanol is a known penetration enhancer and would ideally not be used in a formulation containing DEET, a compound known for its potential toxicity. DEET formulations were prepared containing up to 20% w/w gamma-cyclodextrin (GCD) or 30% w/w hydroxypropyl-beta-cyclodextrin (HPBCD). These formulations were evaluated by determining the release rate of DEET from its vehicle through a synthetic membrane into a receiver medium with a high affinity for DEET using a fully automated Franz-diffusion cell system. DEET release was measured by ultraviolet spectrophotometry at 260 nm. Both the traditional Higuchi release model and an alternate repeated measures analysis of variance with nested factors were used to analyze the data. The influence of the cyclodextrins on the volatility of DEET was determined by solid-phase microextraction. Morphological characterization of the formulations was performed by light microscopy. Physical stability of the formulations was evaluated by rheology in an accelerated study performed at 50 degrees C for 28 days. The cyclodextrins caused a decrease in the release of DEET from its vehicle compared with an ethanol-containing formulation. This effect became more pronounced as the amount of cyclodextrin in the formulation was increased. The addition of the cyclodextrins resulted in a cream-like product compared with the ethanol formulation, which was a lotion. The DEET formulations had the following rank order of volatility: ethanol < DEET = GCD < HPBCD. Examination of the formulations by light microscopy indicated that the CD-based formulations produced a smaller and more homogeneous droplet size distribution than the ethanol-based formulations. The accelerated physical stability study indicated that cyclodextrin-based formulations are both technically and commercially feasible. Cyclodextrins are a promising alternative to ethanol in DEET-containing formulations. The reduced release rate of DEET from these formulations suggests that the toxic potential of DEET may be decreased in these products, while its repellency and stability are maintained.

Administration, Topical↗

PubMed2006

Interaction of indole derivatives and tryptophan peptides with interfaces of sodium dodecyl sulfate micelles.

The free energies of transfer for indole and tryptophan derivatives and pentapeptides having single tryptophan residues from aqueous to sodium dodecyl sulfate (SDS) micellar phases have been systematically studied using the conventional method of ultraviolet absorption spectrophotometry. The free energies for the position isomers of methyl indoles varied depending on the substitution positions. Thus, the contribution of the methyl group to the binding affinity of the 4-methyl indole to the micelle was about twice that of the 2- and 7-methyl indoles. The free energy changes with the introduction of halogen groups to the indole rings were correlated to the nonpolar water-accessible surface area (DeltaA(np)) of the halogen moieties, which were regarded as hydrophobic. The relationships followed straight lines passing through the origins. Position dependence having tendencies similar to the methyl indoles was observed among the magnitudes of the slopes of the straight lines. These results strongly suggest that the indole rings of the derivatives residing in the micellar interface regions direct their imino moieties --NH-- toward the micellar surfaces. Experiments using model tryptophan pentapeptides showed that the magnitude of free energy change per methylene unit of an alkyl amino acid residue in the pentapeptide increased with elongation of the alkyl moiety and was not a constant value as reported for various alkyl compounds. When the peptides distribute to the SDS micelles, the peptide backbones are anchored in aqueous phases and the amino acid side chains in the interfaces extend their alkyl groups toward the micellar centers. Thus, the free energy changes can be connected to the positions of the alkyl groups of the amino acid residues in the micelles.

Algorithms↗

PubMed1997

Low density lipoproteins as drug carriers in the therapy of macrophage-associated diseases.

Low density lipoproteins (LDL) are internalised by the LDL receptor, which is expressed on the surface of eucaryotic cells. Metabolisation and chemical modification of LDLs lead to a shift in receptor affinity: modified LDLs are internalised through scavenger receptors, which are expressed on cells of the monocyte/ macrophage lineage. Coupling of substances with pharmacological activity, such as azidothymidine, to LDL results in a cell specific uptake of these drugs into macrophages by the scavenger receptor. Thus, drug-LDL derivatives might work as tools for macrophage specific drug targeting. In this context, it is essential to know the drug binding capacity, the optimal derivatization conditions, and the amount of drug molecules covalently bound to the LDL particle. In this study, we compared methods for optimal derivatisation and estimation of coupling efficiency, such as semi-quantitative lipoprotein gel electrophoresis, ultraviolet (UV) spectrophotometry, radiometric quantification, and specific protein hydrolysis.

Amino Acids↗

PubMed1996

The precipitate formed by thiopentone and vecuronium.

PURPOSE: To determine the composition and solubility of the precipitate formed by thiopentone and vecuronium in vitro. METHODS: The precipitate formed by mixing thiopentone 2.5% and vecuronium 0.1% at room temperature was analyzed by ultraviolet spectrophotometry and high performance liquid chromatography (HPLC). The solubility of the precipitate in human plasma was measured by HPLC. RESULTS: The UV absorption spectrum of the precipitate resembled that of thiopentone. HPLC analysis produced a single peak with the same retention time as thiopentone (4.6 min). In human plasma the solubility of the precipitate was not different from that of thiopentone acid. The solubility of thiopentone was greater than that of the precipitate. CONCLUSION: The precipitate formed by thiopentone and vecuronium in vitro consisted of thiopentone acid, which was insoluble in human plasma.

Chemical Precipitation↗

PubMed2005

Biphasic interaction of gamma-globulin with copper cations.

Interactions of human serum gamma-globulin with copper cations in solution were studied by differential ultraviolet spectrophotometry. Copper in supraphysiological concentrations increases optical density of protein solution, reflecting the effect of gamma-globulin saturation with metal. In physiological and lower concentrations of copper cations we observed hypochromia in the protein absorption spectrum. Conformational changes in g-globulin molecule during interactions with copper by the surface and intramolecular binding sites and possible role of bivalent metal cations in the maintenance of certain conformations of immunoactive serum proteins are discussed.

Cations↗

PubMed1981

Harmaline distribution in single muscle fibres and the inhibition of sodium efflux.

Harmaline, a known inhibitor of the (Na+ + K+)-ATPase in cell membranes, inhibited 50% of the 22Na efflux from barnacle muscle fibres at an extracellular concentration of 2.4 mM. Injected harmaline inhibited 50% of the efflux at an estimated intracellular concentration of about 8 mM . kg-1, assuming complete equilibration with no binding. Total fibre harmaline was measured in separate fibres by ultraviolet spectrophotometry. Fibres in 3 mM harmaline saline accumulated harmaline with a half-time of 17 min and a final total fibre concentration of 6-12 mM . kg-1. In harmaline-free saline this accumulated harmaline was lost exponentially with a half-time of 35 min; injected harmaline was lost exponentially from fibres with a half-time of 50 min. It is proposed that harmaline crosses the fibre membrane as the uncharged base and that its apparent accumulation against a concentration gradient is mainly due to intracellular binding with an additional contribution from a transmembrane ph gradient. It is concluded that, in fibres exposed to harmaline saline, the intracellular concentration can reach a sufficiently high value, as judged from the results of the injection experiments, to inhibit Na+ efflux at an interior-facing site on the fibre membrane. In contrast, harmaline appears to inhibit the Na+-dependent uptake of L-glutamate at an extracellular site.

Alkaloids↗

PubMed1978

Yeast 3-phosphoglycerate kinase. Essential arginyl residues at the 3-phosphoglycerate binding site.

Yeast 3-phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phospho-transferase, EC 2.7.2.3) is inactivated by phenylglyoxal. Loss of activity correlates with the modification of two arginyl residues, both of which are protected by all of the substrates. The modification is not accompanied by any significant conformational change as determined by optical rotatory dispersion. Ultraviolet difference spectrophotometry indicates that the inactivated enzyme retains its capacity for binding the nucleotide substrates whereas the spectral perturbation characteristic of 3-phosphoglycerate binding is abolished in the modified enzyme. The data suggest that at least one of the two essential arginyl residues is located at or near the 3-phosphoglycerate binding site. A likely role of this residue could be its interaction with the negatively charged phosphate or carboxylate groups of 3-phosphoglycerate.

Arginine↗

PubMed1975

State and reactivity of tryptophyl residues in two bacterial proteases from Sorangium sp.

The state and reactivity of tryptophyl residues in two proteolytic enzymes from Sorangium sp. were investigated by means of the following methods: spectrophotometric oxidation of tryptophans with N-bromosuccinimide, 2-hydroxy-5-nitrobenzyl bromide, and H2O2 in dioxane, optical rotatory dispersion, ultraviolet difference spectrophotometry, solvent perturbation and viscosity measurements. Out of two tryptophyl residues/molecule of alpha-lytic protease, one appears to be completely buried, while the other seems to be exposed. None of these two residues seem to be responsible for the activity of the enzyme. The beta-lytic protease undergoes an irreversible conformational transition between pH 5.0 and 3.5. Out of total four tryptophyl residues/molecule, only one is fully exposed at neutral pH. The other three are gradually exposed in the pH transition region. The degree of exposure and the dimensions of "cavities" shielding tryptophyl residues were estimated. The tryptophyl residues of of beta-lytic protease do not seem to participate in substrate binding or the active site; they are rather one of the determinants of the conformational state of the enzyme.

2-Hydroxy-5-nitrobenzyl Bromide↗

PubMed1981

Some properties of the irreversible complexes of nitracrine (ledakrin, C-283) with polynucleotides.

In the presence of sulfhydryl compounds an anticancer drug nitracrine (NA), 1-nitro-9-aminoalkylacridine derivative forms strong, probably covalent complexes with DNA. It has been found that it binds with similar efficiency to RNA and DNA exhibiting a certain preference for single-stranded structure. At NA/polynucleotide ratio of 0.15 and nucleic acids concentration 100 microgram/ml the numbers of drug molecules bound per 10(3) nucleotides were about 10--13 for native calf thymus DNA, 19--28 for denatured DNA and 23--36 for RNA. Some base specificity to guanine is observed both in polydeoxyribo- and polyribonucleotides. The complexes of NA with DNA and double-stranded synthetic polynucleotides exhibit decreased transcriptional template activity in bacterial RNA synthesis in vitro system except poly(A) synthesis on poly(dA) x poly(dT) which is insensitive to the drug. The drug binding in vitro leads to cross-link formation in DNA as shown by means of ultraviolet spectrophotometry and hydroxylapatite chromatography of heat-denatured NA-DNA complexes. The amount of the double bonds introduced by the drug is however relatively low as compared with cross-linking of irradiated 8-methoxy-psoralen-DNA (MOP-DNA) complexes.

Aminoacridines↗