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At least 1,387 records · Page 77Linked to original sources
PubMed1984

Adenine pool catabolism in the ischemic, the calcium-depleted ischemic, and the substrate free anoxic isolated rat heart: relationship to contracture development.

Metabolic changes in the myocardial adenine and hypoxanthine pools of isolated rat hearts subjected to global ischemia, hypocalcemic global ischemia, and global substrate-free anoxia were compared. At timed intervals between 0 and 60 min separate aliquots of extracts of the ventricles were used to determine either tissue pH, or the components of the adenine pool and their catabolites by reverse phase high performance liquid chromatography (HPLC). The coronary perfusate draining from anoxically perfused hearts was collected over perchloric acid, neutralised and chromatographed by HPLC. The development of left ventricular resting tension (contracture) was recorded in the three groups of hearts. After 60 min ischemia the major catabolites, (AMP, inosine and hypoxanthine) comprised 70% of the total pool (11, 7 and 4 mumol/g dry wt, respectively). After the same period of anoxia 50% of the total pool, comprising adenosine, inosine, hypoxanthine and uric acid in approximately equal proportions, was recovered from the coronary perfusate. The major products remaining in the tissue were IMP and, to a lesser extent AMP (8 and 5 mumol/g dry wt, respectively). Left ventricular contracture developed at different rates in the three groups of hearts but always correlated closely with the maximum rate of adenine pool catabolism. The loss of components from the tissue and the divergence in pathway from adenosine to IMP production which occurs during anoxic perfusion should possibly be considered when assessing the biochemical events occurring in regionally ischemic heart muscle with significant residual flow.

Adenine↗
PubMed1993

Characterization of human prostate cancer, benign prostatic hyperplasia and normal prostate by in vitro 1H and 31P magnetic resonance spectroscopy.

In vitro 1H and 31P magnetic resonance spectra were acquired from perchloric acid extracts of human prostate tissue obtained by transurethral resection. This included tissue of patients with benign prostatic hyperplasia and prostatic adenocarcinoma; one tissue sample was obtained from a patient without any sign of BPH or malignancy. Major resonances in the magnetic resonance spectra were assigned to prostate compounds and were quantified. The citrate/lactate, citrate/total choline, phosphocholine/total creatinine, choline/total creatine, alanine/total creatine, phosphoethanolamine/total phosphate, phosphocholine/total phosphate and glycerophosphoethanolamine/total phosphate ratios were statistically different for the prostate cancer samples as compared with the BPH specimens. These observations may contribute to the understanding of in vivo magnetic resonance spectra of the prostate and indicate that magnetic resonance spectroscopy can aid in the diagnosis of prostate malignancy.

Adenocarcinoma↗
PubMed1991

Characterization of prostate cancer, benign prostatic hyperplasia and normal prostates using transrectal 31phosphorus magnetic resonance spectroscopy: a preliminary report.

We assessed the ability of 31phosphorus (31P) transrectal magnetic resonance spectroscopy to characterize normal human prostates as well as prostates with benign and malignant neoplasms. With a transrectal probe that we devised for surface coil spectroscopy we studied 15 individuals with normal (5), benign hyperplastic (4) and malignant (6) prostates. Digital rectal examination, transrectal ultrasonography and magnetic resonance imaging were used to aid in accurate positioning of the transrectal probe against the region of interest within the prostate. The major findings of the in vivo studies were that normal prostates had phosphocreatine-to-adenosine triphosphate (ATP) ratios of 1.2 +/- 0.2, phosphomonoester-to-beta-ATP ratios of 1.1 +/- 0.1 and phosphomonoester-to-phosphocreatine ratios of 0.9 +/- 0.1. Malignant prostates had phosphocreatine-to-beta-ATP ratios that were lower (0.7 +/- 0.1) than those of normal prostates (p less than 0.02) or prostates with benign hyperplasia (1.1 +/- 0.2, p less than 0.01). Malignant prostates had phosphomonoester-to-beta-ATP ratios (1.8 +/- 0.2) that were higher than that of normal prostates (p less than 0.02). Using the phosphomonoester-to-phosphocreatine ratio, it was possible to differentiate metabolically malignant (2.7 +/- 0.3) from normal prostates (p less than 0.001), with no overlap of individual ratios. The mean phosphomonoester-to-phosphocreatine ratio (1.5 +/- 0.5) of prostates with benign hyperplasia was midway between the normal and malignant ratios, and there was overlap between individual phosphomonoester-to-phosphocreatine ratios of benign prostatic hyperplasia glands with that of normal and malignant glands. To verify the in vivo results, we performed high resolution magnetic resonance spectroscopy on perchloric acid extracts of benign prostatic hyperplasia tissue obtained at operation and on a human prostatic cancer cell line DU145. The extract results confirmed the differences in metabolite ratios observed in vivo. We conclude that transrectal 31P magnetic resonance spectroscopy can characterize metabolic differences between the normal and malignant prostate.

Adult↗
PubMed1999

Sensitive high-performance liquid chromatographic method for determination of captopril in plasma.

A rapid, simple and sensitive high-performance liquid chromatographic method for the determination of captopril in plasma has been developed. Captopril is derivatized with a new reagent, 2-bromo-2'-acetonaphthone to form a product that showed ultraviolet-absorbing properties. For plasma samples, the protein was removed with 6% perchloric acid and the derivatized captopril was extracted with diethyl ether. The chromatographic separation was performed on an analytical mu bondapak NH2 column (300 x 3.9 mm, i.d.) with an isocratic mobile phase consisting of n-hexane-2-propanol-methanol-acetic acid (68:15:15:2). Using ultraviolet detection at 246 nm, the quantification limit for captopril in plasma was 10 ng/ml. The calibration curve was linear over the concentration range 12.5-500 ng/ml. The average recovery was 95% for plasma. The inter-day and intra-day assay coefficients of variation were found to be less than 12%.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Urinary adenosine excretion in patients receiving amphotericin B.

BACKGROUND: Intravenous amphotericin B (AMB) administration in animals causes renal vasoconstriction, ischemia, and oliguria that may result in irreversible renal injury; the mechanism of AMB nephrotoxicity may be similar in human beings. Adenosine is excreted in urine by the ischemic kidney. We hypothesized that adenosine excretion and oliguria would be a marker for patients who later would manifest AMB-associated renal insufficiency and that pre-AMB saline administration (which ameliorates AMB nephrotoxicity) would negate the change in adenosine excretion and urine output. METHODS: Twenty hospitalized patients being treated at the direction of their attending physician and who were receiving AMB (15 to 75 mg intravenously) had urine collected for 1 hour before and for 2 hours during AMB infusion. Eleven patients received normal saline solution (500 ml intravenously) before the AMB infusion; the other nine formed the comparator group. An aliquot of each urine collection was precipitated with perchloric acid to remove protein and cellular elements and centrifuged, and the supernatant was assayed for adenosine by using high-pressure liquid chromatography. RESULTS: Infusion of AMB was associated with a decrease in mean urine output both in patients who received saline solution (245 before versus 149 ml/hr during AMB infusion, p = 0.04) and in patients in comparator group (139 versus 89 ml/hr, p = 0.027). The mean urinary adenosine excretion was unchanged in the saline-loaded group (0.1354 before versus 0.1255 mmol/hr during drug infusion, p = 0.25) and was decreased in the comparator group (0.2276 versus 0.1127 mmol/hr, p = 0.01). Development of renal insufficiency did not correlate with the change in urine output or adenosine excretion. CONCLUSIONS: AMB infusion in human beings results in decreased urine output and decreased adenosine excretion. The latter effect is prevented by a pre-AMB saline load. The changes in urine output and adenosine excretion are not predictive of the development of renal insufficiency.

Adenosine↗
PubMed1982

Detection of different functional states of the cellular nucleus with a new trichrome staining technique.

The new trichrome stain ASTRIN, prepared from alcian blue, safranine, thionine, and resorcin, stains the cell nuclei red or blue, depending on their functional state. Activation of salivary gland cells with pilocarpin, or of liver cell with prednisolone, equally resulted in a quantitative increase of cells with active (blue) nuclei. Changes in nuclear staining after digestion with trypsin, pronase, or ribonuclease, and after extraction of cellular DNA and RNA with perchloric acid, unequivocally suggest that alteration of the protein-DNA ratio, i.e. the hetero- or euchromatic state of nuclear chromatin, is responsible for the disparity of the nuclear staining reaction with ASTRIN. The new trichrome stain seems to be suitable for routine cytodiagnostic use.

Animals↗
PubMed1980

Lack of difference in blood acetaldehyde of alcoholics and controls after ethanol ingestion.

Ethanol and acetaldehyde (AcH) metabolism were studied in male Caucasian alcoholic subjects and matched controls following 1 g/kg ethanol, which was administered after a 10 day, ethanol-free period. The rate of ethanol elimination was higher (p greater than 0.05) in the alcoholics (0.120 g/kg/hr) than in controls (0.108 g/kg/hr). Blood AcH concentrations were measured in either the supernatants of whole blood deproteinized with perchloric acid (PCA) or from the supernatants of PCA-treated plasma obtained from blood added to isotonic semicarbazide. There was no differences between the alcoholic and control subjects for AcH in blood dripped directly into the PCA. The blood AcH concentrations decreased from 22 microM (controls) and 23 microM (alcoholics) to 7 microM (controls) and 3 microM (alcoholics) at 1 and 7 hours after the start of drinking, respectively. No significant AcH was found in blood first taken into heparinized tubes before deproteinization with PCA, after correction for artifactual AcH formation was made. As well, no significant AcH was measured by the semicarbazide method after correction for artifactual AcH. These results suggest that elevated blood AcH levels after ethanol ingestion cannot be taken as a general marker of alcoholism.

Acetaldehyde↗
PubMed1996

Interpretation of chemically created periapical lesions using direct digital imaging.

Perchloric acid (70%) was used to create simulated periapical lesions in tooth sockets of 15 dentate cadaver jaw specimens. Using the Trophy USA direct digital radiographic system, linear images were captured at selected time intervals after initial acid application and altered by contrast reversal, pseudocolor enhancement, and two forms of histogram equalization. The 525 total images were randomized for display on a computer monitor for evaluation by five endodontists. Images were evaluated twice by each rater, with viewings 1 to 2 wk apart. Statistical analysis determined interrater variability, intrarater reproducibility, and the relative merits of each enhancement technique. At 8, 12, 16, and 24 h after acid application, both techniques of histogram equalization yielded a statistically significant improvement over reverse contrast in perception of periapical patholais. Linear and pseudocolor-enhanced images were also significantly more diagnostic than reverse contrast at 12, 16, and 24 h. Intrarater reproducibility showed moderate agreement, but analysis showed only a fair level of interrater agreement.

Alveolar Bone Loss↗
PubMed1996

Interpretation of chemically created lesions using direct digital imaging.

This study compared conventional radiography to digital imaging in detecting chemically created lesions. Six human cadaver jaw specimens were used. A 70% perchloric acid solution was used to create lesions on the buccal cortical plate of each specimen. Digital imaging and conventional images were created after progressing time increments; each increment represented a more advanced lesion. The images were randomly evaluated by five evaluators. This study concluded: (i) when no lesion existed, there was no significant difference in digital imaging or conventional radiography in early detection; (ii) at 12 and 24 h, digital imaging demonstrated lesions significantly earlier than conventional radiography (p = 0.0001); (iii) no difference could be found between imaging techniques at 36 h and thereafter; and (iv) there were no significant differences in the various RadioVisioGraphy enhancement settings used at any of the time points examined.

Analysis of Variance↗
PubMed1980

A rapid assay to measure collagen synthesis in cell cultures.

Limited pepsin digestion and precipitation of resistant parts of proteins with perchloric acid on glass-fiber filters has been used as a rapid way to determine the radioactive collagen secreted into fibroblast culture media. The specificity of the pepsin cleavage was tested by digesting [14C]- or [3H]proline- and [3H]tyrosine-labeled procollagens. Radioactivities obtained with this method were comparable with those obtained with collagenase digestions or hydroxyproline determinations. Dialysis of the samples is avoided and the radioactive collagen can thus be determined from the small medium samples obtained from microtest plates. The method was used to localize a collagen synthesis-increasing factor in preparative isoelectric focusing of microphage culture media.

Animals↗
PubMed1998

cDNA cloning and Escherichia coli expression of UK114 tumor antigen.

Experimental evidence indicates that the antineoplastic effects of UK101, a goat liver perchloric acid extract, is likely due to one of its constituent proteins: the 14 kDa protein named UK114. The cDNA encoding UK114, obtained by PCR methodologies, contains an open reading frame coding for a protein of 137 amino acids with a theoretical molecular mass of 14298 Da. It shows high sequence homology with a 14 kDa protein identified in human, rat and Mus musculus tissues which is likely involved in the inhibition of cell-free protein synthesis. Northern blot analysis indicated that the transcript is present in variable amounts in a wide range of human tissues. Genomic Southern blots revealed that the UK114 mRNA in goat as well as in human is encoded by a single gene, as is the case in rat. The expression system for UK114 was constructed under the control of the PL promoter from bacteriophage lambda and the cDNA coding region has been highly expressed in Escherichia coli as a thioredoxin fusion protein. The recombinant UK114, purified to homogeneity, is immunoreactive to rabbit antisera prepared against UK101 or native UK114, as well as to sera of UK101-treated cancer patients. It inhibits cell-free protein synthesis at 8 microM concentration.

Amino Acid Sequence↗
PubMed2000

Analysis of sugar metabolism in an EPS producing Lactococcus lactis by 31P NMR.

Sugar metabolism and exopolysaccharide (EPS) production was analysed in Lactococcus lactis by in vivo 31P NMR. Transient production of several sugar phosphates, transient depletion of intracellular phosphate, transient production of ATP and UTP, transient acidification of the medium and alkalinisation of the cytoplasm could be observed in a period of 20 min upon energization by the addition of glucose. EPS and non-EPS producing variants showed similar NMR spectra, the exception being two pH-dependent resonances observed in the former. They were already observed before addition of glucose and their response to glucose incubation reflected exposure to the medium. They are presumably phosphorylated poly- or oligosaccharides being loosely adhered to cell walls. By freezing and perchloric acid extraction of the cell material, different types of phosphorylated compounds could be recognised in the NMR spectra such as fructose-1-6-diphosphate, nucleotides (like ADP, ATP, UTP and TDP) and several nucleotide sugars. The ongoing work is focused on identifying the unknown peaks and quantifying the differences between wild-type cells and the EPS producing variant.

Adenosine Diphosphate↗
PubMed2003

Compartmentation of metabolism probed by [2-13C]alanine: improved 13C NMR sensitivity using a CryoProbe detects evidence of a glial metabolon.

The labelling of metabolites with the NMR active nucleus 13C allows not only metabolite enrichments to be monitored, but also the relative fluxes through competing pathways to be delineated. [2-13C, 15N]alanine was used as a metabolic probe to investigate compartmentation in superfused cerebral slices. Perchloric acid extracts of the tissue were investigated using 13C NMR spectroscopy. The spectra were obtained using a CryoProbe optimised for 13C detection (dual CryoProbe [13C, 1H]) in which the receiver and transmitter coils are cooled to approximately 20K to reduce contributions to noise in the signal obtained. Compared with conventional inverse geometry probe, the signal-to-noise ratio (S/N) was increased by approximately 17-fold using this device. A large proportion of alanine was initially metabolised over the first 20 min by glial cells, as indicated by the relative importance of the glial, only enzyme pyruvate carboxylase to the labelling pattern of glutamate, with the ratio of pyruvate carboxylase to pyruvate dehydrogenase derived glutamate being 0.25, and exported [2-13C, 15N]aspartate. Using the increased sensitivity of the CryoProbe, [2-13C, 15N]aspartate was also detected in the extracts of cerebral tissue. This metabolite could only have been derived via the pyruvate carboxylase pathway, and given the large export of the metabolite into the superfusion buffer suggests the occurrence of a "metabolon" arrangement of enzymes within glial cells.

Alanine↗
PubMedDate not supplied

Psychosis in Alzheimer disease: postmortem magnetic resonance spectroscopy evidence of excess neuronal and membrane phospholipid pathology.

BACKGROUND: The presence of psychotic symptoms in Alzheimer Disease subjects (AD+psychosis, AD+P) is a marker for a phenotype characterized by more severe cognitive impairment and a more rapidly deteriorating course. Although AD+P has been inconsistently associated with more severe neuropathology, no prior studies have examined measures of neuronal and synaptic integrity. OBJECTIVE: To determine whether AD+P is associated with evidence of disrupted neuronal and synaptic integrity, as indicated by magnetic resonance spectroscopy (MRS) measurement of N-acetyl-L-aspartate and the membrane breakdown products, glycerophosphocholine and glycerophosphoethanolamine. METHODS: 31P and 1H MRS studies of perchloric acid extract from postmortem brain of AD subjects with and without a history of psychotic symptoms. All subjects were characterized for the presence of comorbid cortical Lewy body pathology and for history of neuroleptic use. Brain tissue from dorsolateral prefrontal, superior temporal, inferior parietal, and occipital cortex, amygdala, and cerebellum were examined in all subjects. Statistical analysis accounted for correlated observations across brain regions within-subjects. RESULTS: AD+P subjects demonstrated significant elevations of glycerophosphoethanolamine and significant reductions of N-acetyl-L-aspartate. Between group differences were greatest in neocortical brain regions. CONCLUSION: Excess impairment of neocortical neuronal and synaptic integrity may provide the structural substrate underlying AD+P. Confirmation of these findings using in vivo MRS measures is indicated.

Aged↗
PubMedDate not supplied

Metabolic alterations in postmortem Alzheimer's disease brain are exaggerated by Apo-E4.

Alterations in phospholipid metabolites are a characteristic abnormality of Alzheimer's disease (AD). Many of these alterations have been demonstrated by magnetic resonance spectroscopy (MRS) studies of postmortem tissue. Phosphodiesters appear to be elevated late in the disease and phosphomonoesters appear to be elevated early in the disease and then decrease. Second to aging, the most robust risk factor for AD identified to date is the presence of the E4 allele of apolipoprotein-E (Apo-E). Because apolipoproteins are intimately involved in lipid metabolism, this study was performed to determine if the presence of the Apo-E4 allele affects the abnormalities in phospholipid metabolites in AD brain. Perchloric acid extracts from 12 Apo-E 3/3, 31 3/4, 6 4/4 AD brains and 5 Apo-E 3/3 control brains were studied by both proton magnetic resonance spectroscopy and phosphorus-31 magnetic resonance spectroscopy. When the E4-positive AD samples were compared with the 3/3 AD samples, an exaggeration in both phosphomonoester and phosphodiester abnormalities was observed. The decrease in N-acetyl-L-aspartate (NAA) was also exaggerated. These results suggest membrane phospholipid metabolite alterations observed in AD are more severe in the presence of the Apo-E4 allele.

Aged↗
PubMed1982

Radioimmunological characterization of carcinoembryonic antigen (CEA) preparations.

A multi-step radioimmunological test system was applied to the characterization of carcinoembryonic antigen (CEA) preparations obtained by column chromatography including ion exchange procedure. CEA contents were estimated by means of a sequential inhibition radioimmunoassay using Protein A-bearing Staphylococci for coprecipitation. Data were expressed as "units CEA" and compared with results obtained from commercial CEA-RIA kits. In addition, attempts were made to evaluate the presence of normal cross-reacting antigens in CEA preparations by the application of an antiserum to perchloric acid extract from normal lung tissue. Data from these tests were expressed as "units NLA" (NLA stands for "normal cross-reacting lung antigen"). The factor "units CEA/units NLA" proved useful as an indication of the tumour specificity of those antigenic components measured in the inhibition assay. Moreover, radioimmunoprecipitation tests with subsequent SDS polyacrylamide gel electrophoretic analysis were performed in order to get information on the molecular weight of the molecule(s) involved in the radioimmunological CEA determination procedure. The test system displayed 1) highly specific CEA reagibility in the standard inhibition assay, 2) test sensitivity of about 200 pg CEA (when related to the Hoffman/La Roche test) and 1 ng CEA (when related to CEA-IRE-SORIN), 3) low reagibility to normal cross-reacting antigens, also when compared to the commercial tests, 4) a molecular weight of about 200,000 daltons for the component(s) measured, and 5) evidence of inhomogeneity of the CEA batches investigated and those international references available. The latter might in part be attributed to so-called species-specific CEA-related determinants. The test system proved also useful for CEA estimations in crude tissue extracts.

Animals↗
PubMedDate not supplied

A semiconductive polymer film sensor for glucose.

The electrical conductivity of organic polymers such as polyacetylene and its derivatives can be varied over twelve orders of magnitude with small amounts (0-3%) of various dopants, such as iodine, bromine, and perchloric acid. Semiconductive polyacetylene film doped with iodine is sensitive to hydrogen peroxide, and can be used as a quantitative hydrogen peroxide sensor. A rapid, quantitative sensor for glucose, using the flavoprotein glucose oxidase, is described and introduces a novel electroactive material, polyacetylene, as the basis for a new biosensor. A significant increase in the sensitivity of this device has been obtained by mediating the doping reaction through lactoperoxidase and potassium iodide.

Acetylene↗
PubMed2003

The solid-solution partitioning of heavy metals (Cu, Zn, Cd, Pb) in upland soils of England and Wales.

Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of "active" humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations.

Cadmium↗