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2.
Sci Total Environ ; 334-335: 251-60, 2004 Dec 01.
Article in English | MEDLINE | ID: mdl-15504512

ABSTRACT

The control and treatment of urban and highway runoff involves a variety of stakeholders in the selection of sustainable drainage systems (SUDS) as the design process needs to consider not only water quantity but also water quality and amenity. Thus, technical, environmental/ecological, social/community and economic cost factors become prime potential sustainability criteria in terms of assessing long-term, cost-effective drainage options. The paper develops a multicriteria analysis methodology for the evaluation and accreditation of SUDS structures within the context of an overall decision-support framework. Approaches independently developed in the UK and France are outlined with the common multicriteria structures defining generic performance criteria together with supporting benchmark standards and exclusion thresholds. A French case study is presented to illustrate the approach and to highlight the inherent constraints and subjectivity embedded in the decision-making process.


Subject(s)
Decision Making , Environment , Vehicle Emissions/prevention & control , Waste Disposal, Fluid , Water Pollution/prevention & control , Benchmarking , Cost-Benefit Analysis , Ecology , France , Policy Making , Social Conditions , Water Movements , Water Pollution/economics
3.
J Chromatogr A ; 881(1-2): 299-307, 2000 Jun 09.
Article in English | MEDLINE | ID: mdl-10905713

ABSTRACT

Dehydroascorbic acid (DHA) is an important, interesting but somewhat enigmatic compound in biological systems. DHA has many unique properties that set it apart from ascorbic acid (AA), and DHA has functions that may be very important beyond that in the AA:DHA cycle. Future studies should help to better clarify chemical activity of DHA and related products that form from DHA, as well as to highlight the role DHA plays in normal cellular homeostasis.


Subject(s)
Dehydroascorbic Acid/analysis , Dehydroascorbic Acid/metabolism , Spectrum Analysis/methods
4.
Am J Hematol ; 64(1): 71-2, 2000 May.
Article in English | MEDLINE | ID: mdl-10815792

ABSTRACT

In a double-blinded placebo-controlled trial of folic acid supplementation in 82 alcoholic subjects, it was found that whole blood folate levels, determined by a mass spectrometric method, do not increase in subjects whose baseline folate levels are above the third quartile (folate sufficiency). Since a state of folate sufficiency can now be identified, a recommended daily allowance (RDA) for folate can be determined using objective means.


Subject(s)
Alcoholism , Folic Acid Deficiency/drug therapy , Folic Acid/administration & dosage , Folic Acid/blood , Hematinics/administration & dosage , Hematinics/blood , Administration, Oral , Adult , Double-Blind Method , Female , Folic Acid Deficiency/blood , Humans , Male
5.
J Chromatogr A ; 862(2): 161-8, 1999 Nov 12.
Article in English | MEDLINE | ID: mdl-10596973

ABSTRACT

The oxidation and reduction of glutathione and oxidized glutathione were studied in real time by liquid chromatography-mass spectrometry during exposure to hydrogen peroxide and mercaptoethanol. By mass spectrometry mixed disulfides and both reversible and irreversible oxidations of sulfur to higher states (sulfinic and sulfonic acids) were directly observed during exposure to hydrogen peroxide. The irreversible oxidation of glutathione to glutathione sulfonic acid could be detected after 30 min exposure of glutathione to 40 mM H2O2 at 20 degrees C. A peak consistent with glutathione-sulfinic acid was transiently present, suggesting this compound behaved as an oxygen consuming antioxidant. Liquid chromatography-mass spectrometry appears to be an excellent method to study oxidation and reductions of sulfur containing peptides and amino acids.


Subject(s)
Glutathione/chemistry , Chromatography, Liquid , Hydrogen-Ion Concentration , Mass Spectrometry , Oxidation-Reduction , Sulfur/chemistry
6.
J Chromatogr B Biomed Sci Appl ; 726(1-2): 79-84, 1999 Apr 16.
Article in English | MEDLINE | ID: mdl-10348173

ABSTRACT

A gas chromatographic-mass spectrometric isotope dilution method was developed for analysis of ascorbate on 10 microl samples of plasma. This assay was reproducible (standard deviation of less than 4%) and gave values for plasma ascorbate content within 8% of our previously published gas chromatographic-mass spectrometric method. Non-specific sample preparation allowed other analytes to be determined on the same sample by adjusting data acquisition parameters and adding the appropriate internal standard. Analysis on 28 subjects fell within the expected range for plasma ascorbate 68+/-29 microm (11.9+/-5.0 microg/ml) and established a normal range for plasma threonate of 28.1+/-2.4 microm (3.8+/-0.4 microg/ml).


Subject(s)
Ascorbic Acid/blood , Gas Chromatography-Mass Spectrometry/methods , Threonine/blood , Calibration , Child, Preschool , Humans , Infant , Reference Standards , Reference Values , Reproducibility of Results
7.
J Clin Gastroenterol ; 28(3): 266-7, 1999 Apr.
Article in English | MEDLINE | ID: mdl-10192620

ABSTRACT

A case of an ulcerated gastric wall mass ultimately found to be splenosis is presented in which the index patient had endoscopic and endoscopic ultrasonographic evaluation prior to resection. Although no visual features identified this mass as a splenic implant preoperatively, the lesion appeared to be atypical for leiomyoma, which led to surgical intervention. The role of endoscopic ultrasonography in assessing isolated gastric masses is discussed.


Subject(s)
Endoscopy, Digestive System , Endosonography , Splenosis/diagnosis , Stomach Diseases/diagnosis , Abdominal Injuries/complications , Abdominal Injuries/surgery , Aged , Diagnosis, Differential , Follow-Up Studies , Humans , Male , Pancreatectomy , Pancreatic Diseases/complications , Pancreatic Diseases/diagnosis , Pancreatic Diseases/surgery , Splenectomy , Splenosis/complications , Splenosis/surgery , Stomach Diseases/complications , Stomach Diseases/surgery
10.
Anal Biochem ; 260(2): 223-9, 1998 Jul 01.
Article in English | MEDLINE | ID: mdl-9657882

ABSTRACT

The interaction of water with dehydroascorbic acid was examined by incubating dehydroascorbic acid and ascorbic acid in 18O-labeled water for various amounts of time and then oxidizing the products with hydrogen peroxide or reducing the products with mercaptoethanol, with analysis by gas chromatography mass spectrometry. Based on mass changes, dehydroascorbic acid readily exchanged three oxygen atoms with H218O. When mercaptoethanol was used to reduce dehydroascorbic acid (which had been incubated in H218O) to ascorbic acid, the newly formed ascorbic acid also contained three labeled oxygen atoms. However, ascorbic acid incubated in H218O for the same amount of time under identical conditions exchanged only two labeled oxygen atoms. Electron impact mass spectrometry of derivatized ascorbic acid created a decarboxylation product which had only two labeled oxygen atoms, regardless if 3-oxygen-labeled or 2-oxygen-labeled ascorbic acid was the parent compound, isolating the extra oxygen addition to carbon 1. These data suggest that dehydroascorbic acid spontaneously hydrolyzes and dehydrates in aqueous solution and that the hydrolytic-hydroxyl oxygen is accepted by carbon 1. Ascorbic acid, on the other hand, does not show this same tendency to hydrolyze.


Subject(s)
Dehydroascorbic Acid/chemistry , Ascorbic Acid/analysis , Desiccation , Gas Chromatography-Mass Spectrometry/methods , Hydrolysis , Kinetics , Models, Chemical , Molecular Structure , Oxidation-Reduction , Oxygen Isotopes , Solutions , Time Factors , Water
11.
Semin Oncol ; 25(2 Suppl 6): 4-11, 1998 Apr.
Article in English | MEDLINE | ID: mdl-9625377

ABSTRACT

Normal digestion is a complex and coordinated process that breaks food into constitutive molecules, some of which are absorbed and others passed through the body as waste. Many of the conditions associated with wasting syndromes alter normal digestive function and can lead to or exacerbate malnutrition. Digestive function can be defined by applying the principles of normal physiology. Our laboratory has developed a relatively comprehensive stable isotope method to assess function, which shows promise as a screening tool in evaluating patients with wasting syndromes. This and other tests of digestive function can be used to define the abnormalities associated with wasting and to direct or optimize antiwasting therapy.


Subject(s)
Digestion/physiology , Wasting Syndrome , Diagnostic Techniques, Digestive System , Gastrointestinal Diseases/complications , Gastrointestinal Diseases/diagnosis , Humans , Wasting Syndrome/etiology , Wasting Syndrome/prevention & control
12.
Anal Biochem ; 255(1): 1-7, 1998 Jan 01.
Article in English | MEDLINE | ID: mdl-9448835

ABSTRACT

The oxidative degradation of ascorbic acid by hydrogen peroxide was examined to determine routes of degradation and identify the initial products which form when ascorbic acid is oxidized. When reacted with hydrogen peroxide, solutions of ascorbic acid and dehydroascorbic acid are both ultimately oxidized to the same species, having a mass spectrum consistent with threonic acid. When the intermediate steps in the oxidation of ascorbic acid are examined in detail, ascorbic acid, dehydroascorbic acid, and solutions containing hydrolyzed dehydroascorbic acid are all oxidized through a six-carbon compound previously proposed to be tetrahydroxydiketohexanoic acid. Both dehydroascorbic acid and hydrolyzed dehydroascorbic acid (diketogulonic acid) are more susceptible to hydrogen peroxide oxidation than ascorbic acid. Based on mass spectral analysis, diketogulonic acid serves as an oxygen sink, implying that it may be a better reducing agent for toxic oxygen species than ascorbic acid. These data indicate that oxidation of ascorbic acid by hydrogen peroxide primarily proceeds through three major six-carbon intermediates, each with distinctive redox properties. The stable metabolite diketogulonic may be a critical antioxidant in ascorbic-acid-containing systems.


Subject(s)
Ascorbic Acid/chemistry , Hydrogen Peroxide/chemistry , 2,3-Diketogulonic Acid/chemistry , Ascorbic Acid/metabolism , Chromatography, Gas , Dehydroascorbic Acid/chemistry , Dehydroascorbic Acid/metabolism , Drug Stability , Hydrogen Peroxide/metabolism , Mass Spectrometry , Oxidation-Reduction , Sensitivity and Specificity
13.
JPEN J Parenter Enteral Nutr ; 22(1): 27-30, 1998.
Article in English | MEDLINE | ID: mdl-9437651

ABSTRACT

PURPOSE: Small intestinal human immunodeficiency virus enteropathy is characterized by profound absorptive dysfunction unrelated to histology or pathogens. Frequently an attempt is made to compensate for this intestinal failure by supplementing nutrient intake with nourishing liquid meals. It is not known how the diminished absorptive function in these patients will respond to this intake. With the use of a D-xylose kinetic model of absorption, we determined the absorptive response of patients with small intestinal enteropathy to an isotonic liquid feeding. METHODS: Seven male patients with acquired immunodeficiency syndrome (AIDS), diarrhea, weight loss, and no detectable pathogens (stool studies and duodenal biopsy) were enrolled. After an overnight fast, the patients were studied on three separate days. On day 1, the patients received 15 g oral D-xylose. On day 2, 10 g i.v. D-xylose was given. On day 3, 15 g oral D-xylose was again given along with 250 mL of a liquid polymeric isotonic diet. Serum and urine collections were obtained to calculate the kinetic rate constants and extent of D-xylose absorption. RESULTS: Mean values for the rate constant for absorption of D-xylose, Ka, (0.26/h; N > 0.65) and the rate constant for nonabsorptive loss, K0' (2.47/h; N < 0.353) were very abnormal before the meal. Mean K0 improved (decreased to 0.66), but Ka and bioavailability, F, did not have a statistically significant change after the meal. The improvement in mean K0 with the meal was much more pronounced in the five subjects with high K0 values before the meal (without meal 3.22: with meal 0.67; p < .05). CONCLUSIONS: (1) An isotonic liquid polymeric diet leads to less nonabsorptive loss of D-xylose, but does not affect the extent of D-xylose absorption in this group as a whole. This is probably due to the meal slowing gastric emptying. (2) Improvement in nonabsorptive loss with a meal is most pronounced when there is excessive nonabsorptive loss, K0, without a meal. (3) Improvement in nonabsorptive losses with a meal might predict which patients will benefit from antimotility agents and continued feedings vs those requiring i.v. hyperalimentation.


Subject(s)
Dietary Sucrose/administration & dosage , HIV Infections/complications , Intestinal Absorption/physiology , Intestinal Diseases/metabolism , Intestine, Small/metabolism , Xylose/metabolism , Administration, Oral , Adult , Fasting , Food, Formulated , HIV Infections/metabolism , Humans , Infusions, Intravenous , Kinetics , Male , Xylose/administration & dosage , Xylose/blood , Xylose/urine
14.
Anal Biochem ; 265(2): 238-45, 1998 Dec 15.
Article in English | MEDLINE | ID: mdl-9882398

ABSTRACT

To identify potential antioxidant compounds derived from ascorbate, the hydrogen peroxide-induced oxidation of ascorbate and dehydroascorbate was studied by gas-chromatography electron impact mass spectrometry and liquid-chromatography electrospray mass spectrometry in real time. Significant differences in ascorbate and dehydroascorbate oxidation occurred at pH 3.3 compared to pH 7.4. Of note, the primary species present in dehydroascorbate (DHA)-containing solutions at pH 7.4 had a spectrum consistent with diketogulonate. Hydrogen peroxide exposure of DHA-containing solutions formed threonate more rapidly at pH 7.4 than at pH 3.3. In these solutions, a 5-carbon species with mass spectral characteristics of a 3,4,5-trihydroxy-2-ketopentanoate appeared to be an intermediate between diketogulonate and threonate, and was more labile than other species in the presence of hydrogen peroxide. These data suggest that a 3,4,5-trihydroxy-2-ketopentanoate is potentially a key antioxidant compound in the ascorbate degradation cascade and in ascorbate-containing solutions at physiologic pH.


Subject(s)
Antioxidants/chemistry , Ascorbic Acid/chemistry , Oxygen/chemistry , Hydrogen-Ion Concentration , Mass Spectrometry , Oxidation-Reduction
16.
Anal Biochem ; 247(1): 58-62, 1997 Apr 05.
Article in English | MEDLINE | ID: mdl-9126371

ABSTRACT

The interconversion of ascorbic acid and dehydroascorbic acid was examined in aqueous solution using unlabeled dehydroascorbic acid and nonlabile, stable isotope-labeled ascorbic acid by gas chromatographic/mass spectrometric analysis. Although the formation of unlabeled ascorbic acid from unlabeled dehydroascorbic acid or labeled dehydroascorbic acid from labeled ascorbic acid did not occur to any significant extent when either solutions of unlabeled dehydroascorbic acid or labeled ascorbic acid were incubated alone, significant amounts of both labeled dehydroascorbic acid and unlabeled ascorbic acid formed when unlabeled dehydroascorbic acid was incubated with labeled ascorbic acid at acid pH. At alkaline pH, interconversion did not occur to any appreciable extent. Likewise, interconversion did not appear to occur in plasma at physiologic concentrations of ascorbic acid, but did occur with pharmacologic concentrations. These data show that ascorbic acid and dehydroascorbic acid interconvert in acidic solution, suggesting the reducing hydrogen atoms are delocalized when ascorbic acid is paired with dehydroascorbic acid under these circumstances. Alkaline pH and plasma inhibit the interconversion.


Subject(s)
Ascorbic Acid/chemistry , Dehydroascorbic Acid/chemistry , Ascorbic Acid/blood , Ascorbic Acid/metabolism , Dehydroascorbic Acid/blood , Dehydroascorbic Acid/metabolism , Deuterium , Gas Chromatography-Mass Spectrometry , Humans , Hydrogen-Ion Concentration , In Vitro Techniques , Kinetics , Oxidation-Reduction , Solutions
17.
J Chromatogr B Biomed Sci Appl ; 690(1-2): 1-6, 1997 Mar 07.
Article in English | MEDLINE | ID: mdl-9106023

ABSTRACT

The synthesis and purification of [13C2]p-hydroxyphenyllactic acid from [13C2]p-hydroxyphenylpyruvic acid, the characterization of tert.-butyldimethylsilyl-derivatized tyrosine, p-hydroxyphenylpyruvic acid and p-hydroxyphenyllactic acid, and an isotope-dilution assay for these substances in normal human plasma using gas chromatography-mass spectrometry (GC-MS) are described. Using this method plasma p-hydroxyphenylpyruvate, p-hydroxyphenyllactate and tyrosine levels of 68 +/- 42 ng/ml, 118 +/- 45 ng/ml and 16.6 +/- 6.3 micrograms/ml, respectively, were found in 9 normal adults. Isotope-dilution assays are sensitive enough to determine tyrosine, p-hydroxyphenylpyruvate and p-hydroxyphenyllactate content in normal subjects, and may be useful for studying disorders of tyrosine metabolism, including inborn errors of metabolism, liver disease and ascorbic acid deficiencies.


Subject(s)
Phenylpropionates/blood , Phenylpyruvic Acids/blood , Tyrosine/blood , Carbon Isotopes , Deuterium , Gas Chromatography-Mass Spectrometry , Humans , Indicator Dilution Techniques
18.
Eur J Clin Nutr ; 51(3): 188-92, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9076410

ABSTRACT

OBJECTIVE: To determine if changes in serum homocysteine values during folic acid supplementation can identify objectively healthy subjects with subclinical folate deficiency. DESIGN: Blood drawn and processed in a regimented fashion from fasting subjects. Serum homocysteine values determined by gas chromatography-mass spectrometry twice before and on days 5 and 8 of daily folic acid supplementation. SETTING: Outpatient University Hospital Clinical Research Center, Denver, Colorado. SUBJECTS: Subjectively healthy adults with normal hematologic and biochemical screening tests. INTERVENTION: Folic acid 1 mg daily for eight consecutive days. RESULTS: Homocysteine values of the group fell significantly during folic acid supplementation. Values pre supplementation were 7.8 +/- 1.8 and 7.4 +/- 2.4 mumol/L while values on days 5 and 8 of supplementation were 6.5 +/- 2.2 and 6.3 +/- 2.2 mumol/L. However, the homocysteine values of any given individual varied up to 60% (rises up to 7 mumol/L and falls of 5 mumol/L) during folic acid supplementation despite the controlled circumstances of blood handling, and an assay coefficient of variation of 8%. CONCLUSIONS: Although group values of serum homocysteine fall during folic acid supplementation, intraindividual variation is so great that subjects with subclinical folate deficiency can not be identified using this study design. Furthermore, these data suggest than an individuals homocysteine values vary enough that single values must be interpreted with caution.


Subject(s)
Folic Acid/administration & dosage , Homocysteine/blood , Adolescent , Adult , Aged , Female , Folic Acid/blood , Folic Acid Deficiency/diagnosis , Folic Acid Deficiency/drug therapy , Gas Chromatography-Mass Spectrometry , Humans , Male , Middle Aged , Vitamin B 12/blood
19.
Methods Enzymol ; 279: 13-24, 1997.
Article in English | MEDLINE | ID: mdl-9211252

ABSTRACT

L-Ascorbic acid, DHA, and the oxidized products derived from AA can be accurately measured using GC/MS. Owing to the complex nature of the reactions through which AA proceeds, we believe that GC/MS is currently the procedure of choice in making AA-related measurements. The methods described are useful in defining reactions involving AA. The methods may indicate in vivo oxidative injury and may allow the use of AA-derived products to determine if antioxidant modulations are effective.


Subject(s)
Ascorbic Acid/analysis , Chromatography, Gas/methods , Mass Spectrometry/methods , Animals , Ascorbic Acid/chemistry , Humans
20.
J Chromatogr B Biomed Appl ; 677(1): 147-51, 1996 Feb 23.
Article in English | MEDLINE | ID: mdl-8925087

ABSTRACT

A new stable isotope dilution gas chromatograph-mass spectrometric method of analysis of homogentisic acid is described. Using this method, homogentisic acid is measured for the first time in normal human plasma. The assay of sera from nine normal individuals yielded a range of values from 2.4 to 12 ng/ml. The method appears to be very sensitive and may be useful in the characterization of heterozygotes for alkaptonuria and other disorders of tyrosine degradation.


Subject(s)
Homogentisic Acid/blood , Alkaptonuria/blood , Alkaptonuria/genetics , Amino Acid Metabolism, Inborn Errors/blood , Amino Acid Metabolism, Inborn Errors/genetics , Gas Chromatography-Mass Spectrometry , Heterozygote , Humans , Radioisotope Dilution Technique , Tyrosine/metabolism
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