SEARCH · PubMed Health

Results for “PERCHLORIC ACID”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 541 records · Page 30Linked to original sources

PubMed1993

Purification and molecular cloning of a novel acidic calmodulin binding protein from rat brain.

An acidic protein was identified among the insoluble proteins of a growth cone-enriched fraction, and this protein was purified from the Triton- and high NaCl-insoluble fraction of newborn rat brain using several column chromatographies after solubilization at an alkaline condition. The purified protein showed a Ca(2+)-dependent calmodulin binding activity. This protein showed an anomalous behavior in SDS-polyacrylamide gel electrophoresis as that observed in case of GAP-43 (neuromodulin, F1, pp46, p57, B-50) and MARCKS (p87, p80), namely shifts of apparent molecular weights under different acrylamide concentrations. Its physicochemical characteristics, such as heat stability, acidic isoelectric point, and solubility in a 2.5% perchloric acid solution, also resemble the properties of these proteins. cDNA cloning of this protein showed that the NH2-terminal 50-amino acid sequence was almost identical to CAP-23, a previously reported chicken protein of unknown function. Since the COOH-terminal half-regions of these proteins are less similar, the entire sequences of these proteins have 65% homology (52% identity), suggesting that these proteins belong to a family. Immunoblotting of several tissue extracts using a monoclonal antibody against this protein showed its specific expression in brain.

Amino Acid Sequence↗

PubMed1976

On the behaviour of murine lymphocytes after in vitro treatment with acid mucoproteins from human serum.

Seromucoproteins from human serum were isolated by perchloric acid extraction followed by DEAE-Sephadex A-50 ion exchange chromatography. The in vitro pretreatment of spleen leukocytes with this fraction caused a dose-dependent inhibition of graft-versus-host reaction as well as an increase of their electrophoretic mobility, the viability being maintained. On contrary, the pretreatment of mice (prospective spleen cell donors of recipients of sheep red blood cells) with human seromucoproteins had no effect on the gvh-reaction as well as on the agglutinin formation to sheep red blood cells under the given conditions. It is supposed that the suppressive effect after in vitro pretreatment may be attributed to a coating effect of seromucoproteins. The fact that spleen cells pretreated in vitro with seromucoproteins are lysed in presence of complement and antiseromucoprotein antiserum supports our opinion. These findings as well as data from the literature support the hypothesis that local concentrated mucoproteins in the skin graft bed in cases of protractedly surviving skin grafts, in the placenta, and on neoplastic tissues can influence unspecifically the immune response. We hope that the understanding of this mechanism may open new possibilities in prolonging allograft survival time.

Animals↗

PubMed1981

Acid digestion determination of iodine in foods.

A method for determining iodine in food is described. The samples were digested using a mixture of sulfuric, nitric, and perchloric acids. The iodine was determined by an automated colorimetric method based on the iodide-catalyzed reduction of Ce+4 by As+3. For milk samples, the relative standard deviation for the method was less than 3%, and the recovery of 125I added to milk and carried through the method ranged from 96 to 102%. The method was compared with 4 other procedures and was superior to alkaline dry ashing methods.

Colorimetry↗

PubMed1996

Evidence for intramineral macromolecules containing protein from plant silicas.

Macromolecular assemblages intimately associated with biogenic silica in plants are released on solubilization of the siliceous phase by treatment with buffered aqueous solutions of HF following treatment of plant material with concentrated oxidizing acids (perchloric, nitric and sulphuric) to remove cytoplasmic contents and the largely polysaccharidic cell wall. The non-dialysable material, which may form 0.015-0.030% dry weight of the silica, has an amino acid composition rich in Pro-Glu, Pro-Lys, or Ser-Asp-Gly depending on the extent of treatment with oxidizing acids. The materials are suggested to have an intrasilica location with materials of similar composition being extracted from the branches of Equisetum telmateia (a primitive plant) and from hairs from the lemma of the grass Phalaris canariensis. The role of such material in regulating nucleation, particle growth and aggregate structure development in silicas is discussed.

Amino Acid Sequence↗

PubMed1996

Effectiveness of microwave based digestion procedures for the demineralization of human milk and infant formulas prior to fluorometric determination of selenium.

The use of two types of microwave oven, one domestic (A) and the other specially designed for laboratory (B) for microwave-based digestion, to destroy the organic matter in milk and infant formulas prior to fluorometric determination of selenium is studied in order to check their applicability and reliability. In both systems the best results were obtained using the acid mixture HNO3-H2O2, and additional treatment with perchloric acid (60%) in a Thermoblock. The application of two different microwave-based digestion procedures to infant formulas was free of interferences. In the case of human milk, it was necessary to use the standard addition method. Values obtained for detection and quantification limits, precision and accuracy of the fluorometric determination of selenium show the usefulness of both digestion procedures. The oven designed for laboratory use (B) is preferential as it permits simultaneous digestion of eight samples.

Female↗

PubMed2002

In situ FTIR studies on the effect of temperature on the electro-oxidation of small organic molecules at the Ru(0001) electrode.

The adsorption and electro-oxidation of formaldehyde, formic acid and methanol at the Ru(0001) electrode in perchloric acid solution have been studied as a function of temperature, potential and time using in situ FTIR spectroscopy, and the results interpreted in terms of the surface chemistry of the Ru(000 1) electrode and compared to those obtained during our previous studies on the adsorption of CO under the same conditions. It was found that no dissociative adsorption or electro-oxidation of methanol takes place at Ru(0001) at potentials < 900 mV vs. Ag/AgCl, and at all three temperatures employed, 10, 25 and 50 degrees C. However, both formaldehyde and formic acid did undergo dissociative adsorption, even at -200 mV, to form linear (CO(L)) and 3-fold-hollow (COH) binding CO adsorbates. In contrast to the adsorption of CO, it was found that increasing the temperature to 50 degrees C markedly increased the amount of CO adsorbates formed on the Ru(0001) surface from the adsorption of both formaldehyde and formic acid. On increasing the potential, the electro-oxidation of the CO adsorbates to CO2 took place via reaction with the active (1 x 1)-O oxide. Formic acid was detected as a partial oxidation product during formaldehyde electro-oxidation. At all three temperatures employed, it was found that adsorbed CO species were formed from the adsorption of both formic acid and formaldehyde, and were oxidised to CO2 faster than was observed in the experiments involving CO adsorbed from CO(g), suggesting a higher mobility of the CO adsorbates formed from the adsorption of the HCOOH and HCHO. At potentials > 1000 mV, both the oxidation of formic acid to CO2 and the oxidation of formaldehyde to both CO2 and formic acid were significantly increased, and the oxidation of methanol to CO2 and methyl formate was observed, all of which were attributed to the formation of an active RuO2 phase on the Ru(0001) surface.

Journal Article↗

PubMed1984

Radioautographic visualization of differences in the pattern of [3H]uridine and [3H]orotic acid incorporation into the RNA of migrating columnar cells in the rat small intestine.

The epithelium of rat small intestine was radioautographed to examine whether RNA is synthesized by the salvage pathway as shown after [3H]uridine injection or by the de novo pathway as shown after [3H]orotic acid injection. The two modes of RNA synthesis were thus investigated during the migration of columnar cells from crypt base to villus top, and the rate of synthesis was assessed by counting silver grains over the nucleolus and nucleoplasm at six levels along the duodenal epithelium--that is, in the base, mid, and top regions of the crypts and in the base, mid, and top regions of the villi. Concomitant biochemical analyses established that, after injection of either [5-3H]uridine or [5-3H]orotic acid: (a) buffered glutaraldehyde fixative was as effective as perchloric acid or trichloracetic acid in insolubilizing the nucleic acids of rat small intestine; (b) a major fraction of the nucleic acid label was in RNA, that is, 91% after [3H]uridine and 72% after [3H]orotic acid, with the rest in DNA; and (c) a substantial fraction of the RNA label was in poly A+ RNA (presumed to be messenger RNA). In radioautographs of duodenum prepared after [3H] uridine injection, the count of silver grains was high over nucleolus and nucleoplasm in crypt base cells and gradually decreased at the upper levels up to the villus base. In the rest of the villus, the grain count over the nucleolus was negligible, while over the nucleoplasm it was low but significant. After [3H]-orotic acid injection, the number of silver grains over the nucleolus was negligible at all levels, whereas over the nucleoplasm the number was low in crypt cells, but high in villus cells with a peak in mid villus. The interpretation is that, except for a small amount of label incorporated into DNA from either precursor by crypt cells, the bulk of the label is incorporated into RNA as follows. In the crypts, cells make almost exclusive use of uridine, that is, of the salvage pathway, for the synthesis of ribosomal RNA in the nucleolus and of messenger and transfer RNA in the nucleoplasm. However, when cells pass from crypt to villus, they mainly utilize orotic acid--i.e., the de novo pathway--for the synthesis of messenger and transfer RNA within the nucleoplasm.

Animals↗

PubMed1980

Amino acid uptake by bovine mammary slices.

A method which measures amino acid uptake by bovine mammary slices is described. Slices of approximately 200 mg were preincubated for 1 h in a modified Krebs-Ringers bicarbonate buffer containing a physiological mixture of amino acids. After preincubation, slices were incubated with radioactive amino acid for 10 min. Slices then were homogenized in perchloric acid, centrifuged, and a sample of the supernate was counted for radioactivity. In parallel experiments, the percent tissue water was determined by drying slices to constant weight. Extra-cellular space of slices was measured with inulin. These measurements allowed uptake to be expressed in terms of amino acid concentration in the cell water. The in vitro uptake pattern of nine essential amino acids was compared to the known in vivo uptake pattern of these amino acids by the cow udder. The correlation between in vitro and in vivo uptake patterns was .91, suggesting that the tissue slice technique can be useful in further study of bovine mammary amino acid transport.

Amino Acids↗

PubMed1992

Identification of neopterin as a potential indicator of infection in burned patients.

Several fluorescent substances are present in the supernatants of acid-precipitated whole blood or plasma from burned patients. Perchloric acid supernatants of sera from infected, but not uninfected, burned rats contained a fluorescent substance with maximum emission at 420 nm at 355-nm excitation (355 ex/420 em). In this study of serum from burned human patients, several fluorescent substances were resolved by reverse-phase high-pressure liquid chromatography. One of these fluorescent components had an high-pressure liquid chromatography retention time and fluorescent characteristics identical to those of neopterin. The identification of this component as neopterin was verified by thermospray mass spectrometry. Serum neopterin concentrations were then determined in supernatants of patient serum samples having various levels of 355 ex/420 em fluorescence. A correlation was found between the concentrations of neopterin determined by high-pressure liquid chromatography and the presence of bacteremia in burned patients. These findings suggest that neopterin, which is a useful indicator of infection in other clinical settings, may also be an indicator of infection in burned patients.

Biopterins↗

PubMed1983

Ion-pair high performance liquid chromatographic determination of inosinic acid in meat.

An ion-pair high performance liquid chromatographic (HPLC) technique is described for the determination of inosinic acid (IMP) in meat. The compound was extracted with perchloric acid and analyzed without cleanup. IMP is effectively separated, identified, and quantitated by using a reverse phase column, with ultraviolet detection. A C8 stationary phase and tetrabutyl ammonium as counter ion are used. Recovery of IMP added to meat at 500 or 2500 ppm levels was more than 95%; the limit of detection for IMP is 50 ppm.

Animals↗

PubMed1987

Partial characterization of alpha 1-acid glycoprotein isolated from mouse serum.

AGP was purified from mouse serum by perchloric acid treatment and CM-Sepharose chromatography. Induction of inflammation with turpentine resulted in a 10-fold increase in the serum level of mouse AGP, indicating mouse AGP is an acute phase reactant. Biochemical characterization of mouse AGP indicated similarity with human and rat AGP.

Amino Acids↗

PubMed1996

Trace analysis in chiral separation of selected amino enantiomers.

A Crownpack CR(+) column was used for the highly sensitive quantitation of amino acid enantiomers. The use of a mobile phase of exclusively aqueous perchloric acid enabled the use of low-wavelength UV detection (200 nm) before on-line derivatization with o-phthaldialdehyde for fluorimetric detection. The use of simultaneous UV and fluorimetric detection permitted the simultaneous quantification of the impurity and its parent compound. The method was used for the evaluation of some commercially available amino acid standards. Enantiomeric impurities as low as 0.001% (10 ppm) can be determined in some cases. High precision for the determination of trace levels of D-amino acids in the presence of large amounts of corresponding L-enantiomer is demonstrated.

Alanine↗

PubMed1991

Use of the Hildebrand grid nebulizer for inductively coupled plasma atomic emission spectrometric analysis of foodware leach solutions and rodent soft tissues and femurs.

The Hildebrand grid nebulizer (HGN) was used for the inductively coupled plasma atomic emission spectrometric determination of major, minor and trace elements in perchloric acid digests of rodent femurs, sulphuric acid digests of rodent soft tissues and in solutions leached from foodware using acetic acid. The HGN performed well when the signal-to-background ratio was optimized for each acid solution by adjusting the injector gas flow, solution uptake rate and observation height. Three problems were overcome while using the HGN: (i) nebulizer wash-out time was reduced by rinsing at high uptake rate with the solution to be analysed; (ii) clogging of the injector tip of the torch during femur analysis was minimized by extensive rinsing; and (iii) errors due to the suppression of the Cu, Fe, Mn and Zn signal intensities by matrix elements Ca and P in femur digests were eliminated by calibrating the spectrometer with matched matrix standard solutions. Overall, the precision of analysis for the leach and tissue solutions analysed in this study ranged from 0.5 to 2.9% relative standard deviation.

Acetates↗

PubMed1987

Recovery of endotoxin from human plasma by acid oxidative treatments as monitored by an automated microtiter plate-chromogenic substrate Limulus amebocyte lysate (LAL) assay method.

Methods to detect endotoxin in human plasma for LAL testing have been developed by use of a perchloric acid (PCA) or a trifluoroacetic acid (TFA) treatment. These acid oxidative treatments eliminate interferences present in plasma. The mode of action of the acids for the elimination of the interferences is indicated to be by their oxidative actions. The treated plasma is assayed by use of an automated microtiter plate-chromogenic substrate LAL assay method employing a modified Cetus Pro/Pette EXPRESS system. The automated system assays 96 samples in approximately 22 minutes. Assay sensitivity of the automated Pro/Pette system is approximately 0.01 endotoxin units (EU) per ml with a linear range from 0.03 to 0.14 EU/ml. The relative standard deviation (RSD) of the assay system is approximately 6%. The improved precision of the LAL assay by the automated system has been attributed to its fast speed (2 minutes) in dispensing the unstable LAL reagent to all 96 samples in one assay block. The total operation, including the acid oxidative treatments and the 96 sample LAL assay, takes approximately 45 minutes. The recovery of spiked endotoxin from plasma ranged from 75 to approximately 100% by adding 0.4 ml of either 0.1-0.2 N PCA or 0.2-0.35 N TFA to 0.2 ml plasma and reacting for 15 minutes at 37 degrees C. The standard deviation of the assay is approximately 0.1 EU/ml plasma. The method has been proven to be rugged, simple, rapid, and cost effective thus would be suitable for clinical application.

Autoanalysis↗

PubMed1990

Identification of a low-Mr acidic nuclear protein as prothymosin alpha.

We have purified to homogeneity a 15-kDa perchloric acid (PCA)-soluble protein from rat thymus nuclei. This highly acidic protein showed a Mr of ca. 30 kDa in acetic acid/urea gels, probably due to oligomer formation. Sequence analysis of internal tryptic and thermolytic peptides revealed that the purified protein is, in fact, prothymosin alpha, a very hydrophilic polypeptide, which has been previously classified as a thymic or immunomodulating hormone. We found that prothymosin alpha is a rather abundant nuclear protein in rat thymus; its concentration is comparable to that of a well-characterized nonhistone protein HMG-14. The subcellular localization and physicochemical properties of prothymosin alpha suggest that its function is related to those of other long polyacidic regions containing nuclear proteins.

Amino Acid Sequence↗

PubMed2005

Two-dimensional supramolecular arrangements of enantiomers and racemic modification of 1,1'-binaphthyl-2,2'-dicarboxylic acid.

Formation of adlayers of the optically active compound 1,1'-binaphthyl-2, 2'-dicarboxylic acid (BINAC) on iodine-modified Au (111) surfaces in perchloric acid was investigated by in situ scanning tunneling microscopy (STM). Highly ordered arrays formed on the surfaces via simple spontaneous adsorption from a solution of enantiomers or the racemic BINAC, in spite of the fact that BINAC has a three-dimensionally complex stereochemical structure. Adlayers of both enantiomers essentially shared the same enantiomorphous structure. Observed parameters of the rectangular unit cell lattice for arrays of both enantiomers of BINAC were a = 2.3 +/- 0.2 nm and b = 0.7 +/- 0.2 nm. On the other hand, racemic modification formed an entirely different adlayer, which consisted of an alternate alignment of the two enantiomers, with an oblique unit cell lattice with parameters of a = 1.2 +/- 0.2 nm, b = 0.8 +/- 0.1 nm, and 74 +/- 3 degrees . No domain composed of a single enantiomer was observed. The stronger hetero-intermolecular interactions of enantiomer couples led to the formation of an alternate arrangement in the array prepared by racemic modification.

Adsorption↗

PubMed1988

Analysis of almitrine and its metabolites in plasma using on-line fast atom bombardment liquid chromatography/mass spectrometry.

To validate a recently developed liquid chromatography/ultraviolet (LC/UV) method in a pharmacokinetic study of Vectarion (almitrine) where the unchanged drug, its five metabolites and an internal standard are analysed, on-line fast atom bombardment liquid chromatography/mass spectrometry (FAB LC/MS) with a moving belt interface has been used. Since the liquid chromatographic conditions required the use of perchloric acid FAB was chosen as ionization mode for the involatile perchlorates formed in the liquid chromatographic process. The use of FAB LC/MS allows the detection of the protonated molecular ions of all the components in the mixture. Furthermore, all the compounds show an intense peak at m/z 203, presenting a liquid chromatographic profile which is very similar to the profile obtained with UV detection.

Almitrine↗

PubMed1996

Determination of gabapentin in plasma by high-performance liquid chromatography.

A rapid and simple method for determination of the novel antiepileptic compound gabapentin [1-(aminomethyl)cyclohexaneacetic acid] in plasma is described. Blank human plasma was spiked with gabapentin (1.0-10.0 micrograms/ml) and internal standard [1-(aminomethyl)-cycloheptaneacetic acid; 5.0 micrograms/ml]. Individual samples were treated with 2 M perchloric acid, centrifuged and then derivatised with o-phthalaldehyde-3-mercaptopropionic acid. Separation was achieved on a Beckman Ultrasphere 5 microns reversed-phase column with mobile phase consisting of 0.33 M acetate buffer (pH 3.7; containing 100 mg/l EDTA)-methanol-acetonitrile (40:30:30, v/v). Eluents were monitored by fluorescence spectroscopy with excitation and emission wavelengths of 330 and 440 nm, respectively. The calibration curve for gabapentin in plasma was linear (r = 0.9997) over the concentration range 1.0-10.0 micrograms/ml. Recovery was seen to be > or = 90%. The inter- and intra-assay variations for three different gabapentin concentrations were < or = 10% throughout. The lower limit of quantitation was found to be 0.5 microgram/ml. Chromatography was unaffected by a range of commonly employed antiepileptic drugs or selected amino acids.

Acetates↗