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PubMed1996

[1-13C]glucose metabolism in brain cells: isotopomer analysis of glutamine from cerebellar astrocytes and glutamate from granule cells.

We analyzed the glutamine isotopomers released into the extracellular medium by cerebellar astrocytes incubated with [1-13C]glucose. We developed a mathematical model of the tricarboxylic acid (TCA) cycle to determine the relative flux of molecules through the anaplerotic versus oxidative pathways and the relative pyruvate carboxylase versus pyruvate dehydrogenase activities. As glutamine C2 and C3 exhibited unequivalent enrichments, we examined the possibility of: (1) both the entry of the label into the TCA cycle from pyruvate and the conversion of the oxaloacetate into citrate before equilibration with fumarate, and (2) the occurrence of an orientation-conserved transfer of the symmetrical 4-carbon intermediates. The best fit required partial cycling between oxaloacetate and fumarate, whereas the occurrence of any orientation-conserved transfer was rejected. On the other hand, the analysis of glutamate isotopomers from perchloric acid extracts of granule cells incubated with [1-13C]glucose indicated that total cycling of oxaloacetate into fumarate occurred in these cells.

Animals↗
PubMedDate not supplied

[Polyamines in representative taxa of coryneform and other bacteria].

The composition of polyamines is studied for the first time in representatives of the genus Micrococcus and taxon "conglomeratus", strains Staphylococcus aureus CCM 209, Deinococcus erythromyxa CCM 706 as well as of Erwinia carotovora ATCC 15713 polyamines, which are not extracted by perchloric acid. Considerable amounts of spermine and rarely of spermidine are revealed in cells of Gram positive microorganisms, that differs them from Gram negative bacteria possessing high concentrations of putrescine, spermidine and their derivatives. A procedure is developed for detection of polyamines in cells of Gram positive microorganisms. It is recommended to use the hydrolysis of their cells by 6N HCl for 4 at 120 degrees C or for 8-10h at 100 degrees C with the subsequent electrophoretic separation. Putrescine, as well as comparable with it amount of agmatine and spermidine traces are found in Erwinia carotovora ATCC 15713 cell hydrolyzates, whereas putrescine and agmatine traces are found in perchloric extracts of intact cells. Spermine is not observed in the cells. The binding of polyamines with biopolymers of cells of Gram positive bacteria and their difference by the given character from the Gram negative procaryotes are under discussion.

Actinomycetales↗
PubMed1980

Phosphorus nuclear magnetic resonance of bovine platelets.

31P nuclear magnetic resonance (NMR) spectra of bovine platelets at 28 degrees C display prominent peaks from adenine nucleotides in two different environments, the metabolic and storage pools. Addition of 20 mM 2-deoxy-D-glucose and 0.1 mM 2,4-dinitrophenol depletes metabolic ATP, resulting in loss of nucleotide signals at 5, 10, and 19 ppm and leaving peaks at 6.5, 10.5, and 19 ppm that are assigned primarily to the dense granule storage pool. The ATP/ADP concentration ratio of the remaining pools is 1.9 +/- 0.2, with chemical shifts which reflect a more acidic environment for the intragranular nucleotides than for the cytosol. Isolated bovine dense granules give spectra with similar peak positions to those ascribed to the storage pool after metabolic depletion of whole cells. Storage pool nucleotide spectra are highly temperature dependent. Below 20 degrees C, the beta-ATP peak broadens and decreases in area to the point that it is almost undetectable at 0 degrees C, probably reflecting formation of progressively higher molecular weight aggregates at the lower temperatures. The release reaction was followed by 31P NMR after addition of thrombin at 28 degrees C. Spectra of the cell suspension taken at 5-min intervals were compared to spectra of perchloric acid extracts produced in parallel. A new finding of these experiments is that the released nucleotides rapidly undergo a transition to a "NMR silent" form as part of the bovine platelet release reacton. Metabolic breadkdown and external paramagnetic ion interactions did not explain the loss of signal from the storage pool. During release reaction, the nucleotides may be broadened out beyond detection due to immobilization by divalent cation and/or platelet membrane binding.

Adenine Nucleotides↗
PubMed2006

In situ stress and nanogravimetric measurements during underpotential deposition of bismuth on (111)-textured Au.

The surface stress associated with the underpotential deposition (upd) of bismuth on (111)-textured Au is examined, using the wafer curvature method, in acidic perchlorate and nitrate supporting electrolyte. The surface stress is correlated to Bi coverage by independent nanogravimetric measurements using an electrochemical quartz crystal nanobalance. The mass increase measured in the presence of perchlorate is consistent with the (2 x 2) and (p x square root 3)-2Bi adlayers reported in the literature. ClO(4)(-) does not play a significant role in the upd process. The complete Bi monolayer causes an overall surface stress change of about -1.4 N m(-1). We attribute this compressive stress to the formation of Bi-Au bonds which partially satisfy the bonding requirements of the Au surface atoms, thereby reducing the tensile surface stress inherent to the clean Au surface. At higher Bi coverage, an additional contribution to the compressive stress is due to the electrocompression of the (p x square root 3)-2Bi adlayer. In nitric acid electrolyte, NO(3)(-) coadsorbs with Bi over the entire upd region but has little fundamental impact on adlayer structure and stress.

Journal Article↗
PubMed2004

Biosorption of water-soluble dyes on magnetically modified Saccharomyces cerevisiae subsp. uvarum cells.

Brewer's yeast (bottom yeast, Saccharomyces cerevisiae subsp. uvarum) cells were magnetically modified using water based magnetic fluid stabilized with perchloric acid. Magnetically modified yeast cells efficiently adsorbed various water soluble dyes. The dyes adsorption can be described by the Langmuir adsorption model. The maximum adsorption capacity of the magnetic cells differed substantially for individual dyes; the highest value was found for aniline blue (approx. 220 mg per g of dried magnetic adsorbent).

Adsorption↗
PubMed1984

Determination of serum and plasma concentrations of retinol using high-performance liquid chromatography.

An isocratic high-performance liquid chromatographic method specifically developed to allow simple and rapid determination of retinol concentrations in serum and plasma is reported. Retinol and retinol acetate (the internal standard) are extracted into butanol-ethyl acetate, with no subsequent evaporation step. Separation is achieved on a reversed-phase C-18 column, with a mobile phase consisting of acetonitrile-1% ammonium acetate (89:11), and UV detection at 313 nm. Recoveries of both retinol and the internal standard were 100%, and both compounds were stable in the extraction solvent for at least 2.5 h. Three anticoagulants (oxalate, citrate, EDTA) and perchloric acid (used in some methods to denature protein) all caused losses of retinol. Each run required 9 min; same-day coefficient of variation (C.V.) for identical samples averaged 2.5%; between-day C.V. was 6.4%; sensitivity was better than 10 ng/ml, while clinical concentrations were 400-1200 ng/ml. This method permits simple, rapid, sensitive, precise, and accurate determination of retinol using 0.5 ml serum or heparinized plasma.

Anticoagulants↗
PubMed1993

Simple decomposition procedure for determination of selenium in whole blood, serum and urine by hydride generation atomic absorption spectroscopy.

A digestion procedure for selenium determination by hydride generation atomic absorption spectroscopy (AAS) in whole blood, serum and urine is described, it employs sulfuric acid, hydrogen peroxide and vanadium (V) sulfuric acid reagent solution. The method is rapid, uses no explosive reagents and can be performed at a constant temperature of 100 degrees C. Therefore, it is easily applicable in a routine clinical laboratory for a large amount of samples. The coefficient of intra-assay variation was 4.3-5.6%, the coefficient for inter-assay variation was 5-5.9% in the medium and high concentration range, and 5.8-8.6% in the low range. In analyzing several commercial reference materials our results showed good agreement with the target values. Analytical recovery by addition of sodium selenite and seleno-DL-methionine to samples ranged between 97 and 104%. The correlation between the described digestion procedure and the nitric, sulfuric and perchloric acid digestion procedure recommended by the International Union of Pure and Applied Chemistry showed good agreement for whole blood, serum and for urine. We determined selenium in serum (n = 58) and whole blood (n = 50) in a collective of healthy children from 1 to 5 years living in Styria, Austria. The low values in serum (35 +/- 11 micrograms/L) and whole blood (42 +/- 6 micrograms/L) at one year of life increased significantly to 48 +/- 13 mu/L (p = 0.033) and 55 +/- 6 micrograms/L (p = 0.004) at three years of life in serum and whole blood, respectively. The selenium concentration showed no further increase up to five years of age.(ABSTRACT TRUNCATED AT 250 WORDS)

Austria↗
PubMed2006

Modifications to increase the efficiency of the fluorometric cycling assay for cyclic ADP-ribose.

Cyclic ADP-ribose (cADPR) is an intracellular messenger that triggers the release of calcium ions from intracellular stores in a variety of cell types. The fluorometric cycling assay has become the preferred method for measuring cADPR due to its high level of sensitivity (in the sub-nanomolar range) and its use of commercially available reagents. Additionally, the assay is performed in multiwell plates, making it suitable for high throughput screening using a fluorescence plate reader. The findings reported in this paper present several problems that may be encountered during various stages of the assay, and provide solutions to these problems. Modifications to the assay address reduced recovery of sample and cADPR with removal of perchloric acid (PCA) using organic solvent, reduction in diaphorase activity with heat treatment, and effects on resorufin fluorescence by pH range. Using these modifications, we report an increase of approximately 15% in recovery of brain cADPR, and show that between-subject variability is greatly reduced. We hope that these observations will encourage more widespread application of this valuable assay.

Animals↗
PubMed2005

Quantitating adenylate nucleotides in diverse organisms.

Quantitation of cellular adenylate levels (i.e., ATP, ADP, AMP) has widespread applications in physiological, metabolic and energetic studies. We have compared classical adenylate extraction procedures (i.e., perchloric acid, boiling) with a previously unreported proteinase K-based extraction technique. Our results suggest that all three techniques are comparable in soft animal tissue, but proteinase K-based extractions consistently generated higher adenylate yields from a broad range of organisms, particularly those containing a cell wall (e.g., alga, bacteria, fungi, plant).

Adenine Nucleotides↗
PubMed1990

Determination of glomerular filtration rate using iohexol clearance and capillary sampling.

Glomerular filtration rate can be conveniently quantified by monitoring the plasma clearance of iohexol. In this study we have evaluated the possibility of further simplifying the investigation by using capillary sampling. Eight women and two men were given a single injection of iohexol (5 ml Omnipaque). Three to 4 h after the injection plasma and capillary samples were taken. Iohexol concentrations in whole blood and in plasma were measured by high-performance liquid chromatography after precipitation with perchloric acid. Iohexol in blood was quantitatively distributed to the plasma compartment. Plasma concentrations of iohexol calculated from the capillary blood concentration and erythrocyte volume fraction were in good agreement with actual plasma concentrations (r = 0.98). The imprecision of iohexol determination in capillary samples was 3.5% (CV) and clearance measurements using venous and capillary sampling also agreed well.

Adult↗
PubMed1989

On the presence of the chromosomal proteins HMG I and HMG Y in rat organs.

Using antiserum raised against HMG I, we have shown that HMG I and HMG Y are present in perchloric acid extracts of kidney, lung, heart, brain, liver and intestine in the rat, suggesting that the expression of these proteins may not be dependent upon proliferative activity. The results also show that the ratio between HMG I and HMG Y varies between different organs.

Animals↗
PubMed1990

Characterization and distribution in human tissues of a glycoproteic antigen defined by monoclonal antibody 1BE12 raised against the human breast cancer cell line T47D.

Spleen cells from inbred Biozzi mice, immunized against the human breast cancer cell line T47D, were fused with murine myeloma SP2O cells to generate monoclonal antibodies. One of these, 1BE12, of IgM isotype, reacted with five of six human breast tumor cell lines, while no binding was detectable with normal lymphocytes, RBC, or fibroblasts. The antigen recognized by monoclonal antibody 1BE12 was localized on the surface of T47D and MCF7 cells and was detected in cell-free supernatants of cultures. The antigen was found also on the surface of milk secretory cells. Immunohistochemical staining of frozen and paraffin-embedded sections of human tissues showed apical polarized reactivity in normal breast glands, while in all breast cancers staining was either cytoplasmic or membranous and heterogeneously distributed. Immunostaining was also observed in some other normal epithelia, including salivary gland, gastroduodenal mucosa, exocrine pancreas, and cervix. The antigen was not detectable in secretory endometrium, whereas proliferative endometrium was strongly stained. Colon carcinoma, and cancers of the bladder and endometrium were strongly reactive. No staining was detected in melanoma, lymphoma, mesothelioma, non-small cell lung carcinoma, and thyroid, renal, and ovarian carcinomas. Lectin absorption of MCF7 membrane extracts reduced 1BE12 binding. A large reduction in 1BE12 reactivity was observed after digestion of T47D and MCF7 membrane extracts with proteases. Treatment with sodium periodate resulted in complete loss of antigenicity, while neuraminidase treatment did not affect 1BE12 binding. These findings suggest that the 1BE12 epitope is expressed on the carbohydrate moiety of a glycoprotein and does not contain sialic acid. Immunoblotting of the perchloric acid-soluble fraction of MCF7 membrane extracts after electrophoresis in 1% agarose detected the antigen as a high molecular weight species (Mr greater than 900,000). The antigen was purified by perchloric acid extraction of MCF7 membrane preparations followed by affinity chromatography on 1BE12 antibody coupled to Sepharose-4B and gel exclusion fast protein liquid chromatography. No reactivity of the purified material was found with monoclonal antibodies directed against human milk fat globule membrane-associated mucins HMFG1 and DF3.

Antibodies, Monoclonal↗
PubMed1978

Collagen turnover and the growth state in 3T6 fibroblast cultures.

The metabolic turnover of collagen in 3T6 fibroblast cultures was studied at various stages of growth by compartmental analysis of hydroxyproline content and of the conversion of radioactive proline to hydroxyproline. Quantitative and radioactive hydroxyproline measurements were directly parallel, although the latter method was more sensitive in demonstrating collagen synthesis in all phases of growth. Hydroxyproline formation as an index of collagen synthesis was abruptly accelerated at the time of confluence, and was well maintained at the new rate despite a gradual decline in the rate of general protein synthesis. Ethanol fractionation of growth medium proved superior to perchloric acid extraction in providing a pool of soluble hydroxyproline clearly derived from collagen degradation. Breakdown products were released at a constant rate per cell in all growth phases and accumulated to high levels in continuous culture. The fractional rate of collagen breakdown (percentage of hydroxyproline radioactivity) was highest in early logarithmic growth. Its gradual decline as cultures aged reflected the increased hydroxyproline content and improved stability of collagen under these conditions.

Cell Division↗
PubMed2004

Polynucleotide phosphorylase-based photometric assay for inorganic phosphate.

Polynucleotide phosphorylase is a prokaryotic enzyme that catalyzes phosphorolysis of polynucleotides with release of nucleotide diphosphates. By taking advantage of this property, we developed a photometric assay for inorganic phosphate. In the presence of polyadenylic acid, phosphate is converted into adenosine 5'-diphosphate (ADP) by this enzyme. ADP then reacts with phosphoenolpyruvate in a pyruvate kinase-catalyzed reaction, thus giving rise to adenosine 5'-triphosphate and pyruvate. Finally, pyruvate oxidizes reduced nicotinamide adenine dinucleotide (NADH) through the action of L-lactate dehydrogenase, with concomitant decrease in absorbance at 340 nm. As expected, in this detection system 1 mol of NADH was oxidized per mole of phosphate. The assay showed an excellent reproducibility, as the standard deviations never exceeded 5%. It also was shown to be unaffected by several compounds that are regarded as major interferents of the traditional colorimetric assays. Absence of interference was also demonstrated when determining phosphate content in different biological samples, such as human serum and perchloric acid extracts from Escherichia coli, yeast, and bovine liver. An E. coli strain overexpressing His-tagged polynucleotide phosphorylase developed in our laboratories allowed quick and straightforward purification of enzyme, making the assay feasible and convenient. Since all other reagents required are inexpensive, the assay represents a cheaper alternative to commercially available phosphate assay kits.

Adenosine Diphosphate↗
PubMed1978

The effect of aldehyde fixation on selected substrates for energy metabolism and amino acids in mouse brain.

The effect of aldehyde fixation on concentrations of low molecular weight constituents was determined by comparing amounts of selected intermediates in brains of mice exposed to aldehyde fixative solutions with those perfused with phosphate buffer solution alone. Aldehyde perfusion resulted in excellent preservation of cerebral cortex ultrastructure in the presence of dramatic declines in adenosine triphosphate, phosphocreatine, glucose and glucose-6-phosphate that occureed before exposure of the tissue to aldehyde fixatives. Decreases in hexose were accompanied by approximately a 4-fold increase in lactate and a 2-fold increase in pyruvate. Glycogen levels decreased by about 60% during the initial operative procedure but remained constant after aldehyde fixation. Glycogen content declined approximately 90% in tissues that were not treated with aldehyde. Concentrations of aspartate and glutamate changed only slightly during the initial period (1-5 min) and remained constant for at least 90 min in cerebral cortices fixed with aldehydes. Alanine levels increased in both fixed and unfixed tissue; however, this increase was much smaller in tissues exposed promptly to aldehydes. Total ninhydrin-positive material in perchloric acid extracts of brain decreased in mice exposed to aldehyde solutions but increased in tissues that were not. These results indicated that several amino acids may be measured reliably in tissues preserved for light and electron microscopy. In addition, determination of glutamate: alanine ratios in tissues perfused with aldehydes may provide an indication of the timing of fixation.

Aldehydes↗
PubMed1994

Analytical evaluation of high energy phosphate determination by high performance liquid chromatography in myocardial tissue.

High performance liquid chromatography (HPLC) is an established method for the determination of myocardial high energy phosphates (HEP). Quantification of HEP compounds in small tissue specimens obtained by endomyocardial biopsy technique requires maximal sensitivity without impairment of precision. Employing isocratic ion-pair reversed-phase HPLC, high sensitivity and precision were obtained by running analyses for adenonucleotides and creatine compounds separately at detection wavelengths of 254 and 210 nm, respectively. Further reasons for separate runs were given by the necessity for different sample preparation as remaining perchloric ion after deproteinizing and pH in the samples had various effects on adenonucleotides and creatine compounds. Mechanical homogenization for 20 s in 0.42 mol/l perchloric acid ensured a consistent myocardial HEP extraction. Sample preparation directly following biopsy sampling is preferable since HEP compounds were labile in tissue within days at -80 degrees C even though an initial metabolic inhibition in liquid nitrogen had been induced. Following extraction and neutralization, HEP compounds were stable for up to 3 months at -20 degrees C.

Biopsy↗
PubMed1992

Determination of mitoxantrone by flow injection analysis using an amperometric detector.

Mitoxantrone was determined by flow injection analysis using a flow cell modified in the laboratory and fitted with carbon paste as an amperometric detector. The sample solution (100 microliters, 5 x 10(-8)-1 x 10(-5) M) was injected into the carrier stream of 0.1 M perchloric acid (pH 1.12). Mitoxantrone was determined by oxidation at the carbon paste electrode (CPE) at +0.90 V. A 60-cm delay coil (0.5 mm i.d.) was incorporated just before the detector (a canal thin layer) and a flow rate of about 4 ml min-1 was used. The system was successfully applied to the determination of mitoxantrone in a pharmaceutical preparation; the method was fast and reproducible.

Electrodes↗
PubMed1991

[Virucidal efficacy of inorganic per-compounds].

Among 7 inorganic per-compounds tested potassium permanganate as 1% solution showed the greatest virucidal efficacy against poliovirus type I and reached a reduction rate of 4.1 after 30 sec exposure time. Potassium peroxomonosulfate produced a reduction rate of 5.6 after 5 min, whereas perchloric acid and sodium perborate needed 15 min and hydrogen peroxide 60 min to show a reduction of 10(4) of the infectivity level. Potassium peroxodisulfate and sodium perborate yielded a reduction rate of 0.9 and 1.3, respectively. With protein load a slight reduction of antiviral efficacy was observed, whereas with extended standing times only the reduction rate of sodium percarbonate was lowered from greater than or equal to 4.9 to 2.0 after 60 min exposure time.

Antiviral Agents↗