The Design, Synthesis and Preliminary Pharmacokinetic Evaluation of d3-Poziotinib Hydrochloride.

To establish a synthetic route to d3-poziotinib hydrochloride. Treatment of 4-chloro-7-hydroxyquinazolin-6-yl pivalate (1) with d3-methyliodide afforded the etherization product, which reacted with 3,4-dichloro-2-fluoroaniline to generate the key intermediate d3-4-(3,4-dichloro-2-fluorophenylamino)-7-methoxyquinazolin-6-yl pivalate (3). Followed the de-protection reaction, the nucleophilic substitution (SN2) reaction with tert-butyl 4-(tosyloxy)piperidine-1-carboxylate (TSP), and the de-protection reaction of t-butoxycarbonyl (Boc) group, and the amide formation reaction with acrylyl chloride, d3-poziotinib was obtained, which was converted to hydrochloride salt by treatment with concentrated hydrochloric acid (HCl). Starting from a known compound 4-chloro-7-hydroxyquinazolin-6-yl pivalate (1), after 7 steps transformation, d3-poziotinib hydrochloride was obtained with a total yield of 9.02%. The structure of d3-poziotinib hydrochloride was confirmed by 1H-NMR, 13C-NMR, and high resolution (HR)-MS. Meanwhile, the in vitro microsomal stability experiment showed that d3-poziotinib had a longer half time (t1/2 = 4.6 h) than poziotinib (t1/2 = 3.5 h).

Synthesis of deuterium-enriched sorafenib derivatives and evaluation of their biological activities.

Deuterium substitution has been widely known that can improve the pharmacokinetic profiles due to isotope effect. Herein, a series of deuterated sorafenib derivatives have been synthesized and characterized by 1H NMR, 13C NMR and MS. Their antitumor activities were evaluated in vitro against human hepatoma cell line HepG2 and human cervical carcinoma cell line HeLa. The LogP values were detected by high-performance liquid chromatography. Subsequently, the metabolic stability and pharmacokinetics study were assessed in vitro and in vivo.

Validation of anthropometric and bioelectrical impedance analysis (BIA) equations to predict total body water in a group of Cameroonian preschool children using deuterium dilution method

BACKGROUND: Little information is available on the validity of anthropometry or impedance-based equations for prediction of total body water (TBW) in African children. This study was designed to validate and develop equations to predict total body water in Cameroonian children. METHODS: TBW was measured by deuterium dilution in 102 children between 24 and 60 months of age and compared with the ones predicted by 5 anthropometric and 7 BIA equations. Multiple linear regression analysis was used to develop prediction equations for TBW from anthropometric parameters. RESULTS: Unacceptable discrepancies in the estimates of TBW at individual level were noted with all the equations tested. The following new anthropometry and BIA equations for the estimation of TBW were respectively developed: TBW = 6.488 + 0.434 × sex−0.039 × age + 0.670 × weight−0.081 × MUAC (cm)−0.372 × BMI (adjustedR2= 0.71,RMSE = 3.6), and TBW =−6.206 + 0.0037 × height2/Z−0.041 × age + 0.265 × weight + 0.1214 × height (adjustedR2=0.68, RMSE = 1.4). The cross-validation procedures revealed that the predicted values of TBW compared with measured values are accurate at a group level. CONCLUSION: The current published anthropometric and BIA equations are invalid for the estimation of TBW in Cameroonian preschool children. The newly developed anthropometry or BIA prediction equations are valid for use in Cameroonian children aged 24­60 months

Comparative In Vitro Study of 11C-Methionine and 11C-Deuterodeprenyl Uptake in Three Human Glioma Cell Lines.

AIM: To compare the uptake of 11C-deuterodeprenyl (11C-DED) and 11C-methionine (11C-MET) in three human glioma cell lines and study the relationship with glial fibrillary acid protein (GFAP) and monoamine oxidase B (MAO B) expression. 11C-DED is used in positron emission tomography imaging as a marker of astrocytosis in various central nervous system pathologies. It binds irreversibly to MAO B, a glial dimeric enzyme with increased activity in some neurological pathologies. MATERIALS AND METHODS: Binding and internalization studies of 11C-MET and 11C-DED were performed in astrocytoma grade III, glioblastoma grade IV, and radio-resistant glioblastoma grade IV cells. Immunofluorescence was used. RESULTS: 11C-MET specific activity bound to membrane was 9.0%-11.1% and that internalized was 88.9%-91.0%. 11C-DED specific activity bound to membrane was 34.8%-58.0% and that internalized was 38.7%-65.2%. Immunocytochemistry revealed GFAP and MAO B expression. CONCLUSIONS: The expression of MAO B measured by 11C-DED uptake or immunocytochemistry was not significantly different in grade III or IV cells. The GFAP signal was higher for grade IV compared to grade III. 11C-MET uptake was high in all the tumor cells. 11C-DED is a dopamine analogue and the transport across cell membranes is expected to be mediated by DAT receptors present in astrocytes. Reactive astrocytes surround tumor lesions; so the authors suggest that the 11C-DED uptake might be caused by the reactive astrocytosis and not by MAO B expression in tumor cells.

The use of stable isotopes in the study of human pathophysiology.

The growing prevalence of metabolic diseases including fatty liver disease and Type 2 diabetes has increased the emphasis on understanding metabolism at the mechanistic level and how it is perturbed in disease. Metabolomics is a continually expanding field that seeks to measure metabolites in biological systems during a physiological stimulus or a genetic alteration. Typically, metabolomics studies provide total pool sizes of metabolites rather than dynamic flux measurements. More recently there has been a resurgence in approaches that use stable isotopes (e.g. 2H and 13C) for the unambiguous tracking of individual atoms through compartmentalised metabolic networks in humans to determine underlying mechanisms. This is known as metabolic flux analysis and enables the capture of a dynamic picture of the metabolome and its interactions with the genome and proteome. In this review, we describe current approaches using stable isotope labelling in the field of metabolomics and provide examples of studies that led to an improved understanding of glucose, fatty acid and amino acid metabolism in humans, particularly in relation to metabolic disease. Examples include the use of stable isotopes of glucose to study tumour bioenergetics as well as brain metabolism during traumatic brain injury. Lipid tracers have also been used to measure non-esterified fatty acid production whilst amino acid tracers have been used to study the rate of protein digestion on whole body postprandial protein metabolism. In addition, we illustrate the use of stable isotopes for measuring flux in human physiology by providing examples of breath tests to measure insulin resistance and gastric emptying rates.

Altering Metabolic Profiles of Drugs by Precision Deuteration 2: Discovery of a Deuterated Analog of Ivacaftor with Differentiated Pharmacokinetics for Clinical Development.

Ivacaftor is currently used for the treatment of cystic fibrosis as both monotherapy (Kalydeco; Vertex Pharmaceuticals, Boston, MA) and combination therapy with lumacaftor (Orkambi; Vertex Pharmaceuticals). Each therapy targets specific patient populations: Kalydeco treats patients carrying one of nine gating mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein, whereas Orkambi treats patients homozygous for the F508del CFTR mutation. In this study, we explored the pharmacological and metabolic effects of precision deuteration chemistry on ivacaftor by synthesizing two novel deuterated ivacaftor analogs, CTP-656 (d9-ivacaftor) and d18-ivacaftor. Ivacaftor is administered twice daily and is extensively converted in humans to major metabolites M1 and M6; therefore, the corresponding deuterated metabolites were also prepared. Both CTP-656 and d18-ivacaftor showed in vitro pharmacologic potency similar to that in ivacaftor, and the deuterated M1 and M6 metabolites showed pharmacology equivalent to that in the corresponding metabolites of ivacaftor, which is consistent with the findings of previous studies of deuterated compounds. However, CTP-656 exhibited markedly enhanced stability when tested in vitro. The deuterium isotope effects for CTP-656 metabolism (DV = 3.8, DV/K = 2.2) were notably large for a cytochrome P450-mediated oxidation. The pharmacokinetic (PK) profile of CTP-656 and d18-ivacaftor were assessed in six healthy volunteers in a single-dose crossover study, which provided the basis for advancing CTP-656 in development. The overall PK profile, including the 15.9-hour half-life for CTP-656, suggests that CTP-656 may be dosed once daily, thereby enhancing patient adherence. Together, these data continue to validate deuterium substitution as a viable approach for creating novel therapeutic agents with properties potentially differentiated from existing drugs.

Biodistribution and radiation dosimetry of deuterium-substituted 18F-fluoromethyl-[1, 2-2H4]choline in healthy volunteers.

UNLABELLED: (11)C-choline and (18)F-fluoromethylcholine ((18)F-FCH) have been used in patients to study tumor metabolic activity in vivo; however, both radiotracers are readily oxidized to respective betaine analogs, with metabolites detectable in plasma soon after injection of the radiotracer. A more metabolically stable FCH analog, (18)F-fluoromethyl-[1,2-(2)H4]choline ((18)F-D4-FCH), based on the deuterium isotope effect, has been developed. We report the safety, biodistribution, and internal radiation dosimetry profiles of (18)F-D4-FCH in 8 healthy human volunteers. METHODS: (18)F-D4-FCH was intravenously administered as a bolus injection (mean ± SD, 161 ± 2.17 MBq; range, 156-163 MBq) to 8 healthy volunteers (4 men, 4 women). Whole-body (vertex to mid thigh) PET/CT scans were acquired at 6 time points, up to 4 h after tracer injection. Serial whole-blood, plasma, and urine samples were collected for radioactivity measurement and plasma radiotracer metabolites. Tissue (18)F radioactivities were determined from quantitative analysis of the images, and time-activity curves were generated. The total numbers of disintegrations in each organ normalized to injected activity (residence times) were calculated as the area under the curve of the time-activity curve normalized to injected activities and standard organ volumes. Dosimetry calculations were performed using OLINDA/EXM 1.1. RESULTS: The injection of (18)F-D4-FCH was well tolerated in all subjects, with no radiotracer-related serious adverse event reported. The mean effective dose averaged over both men and women (± SD) was estimated to be 0.025 ± 0.004 (men, 0.022 ± 0.002; women, 0.027 ± 0.002) mSv/MBq. The 5 organs receiving the highest absorbed dose (mGy/MBq) were the kidneys (0.106 ± 0.03), liver (0.094 ± 0.03), pancreas (0.066 ± 0.01), urinary bladder wall (0.047 ± 0.02), and adrenals (0.046 ± 0.01). Elimination was through the renal and hepatic systems. CONCLUSION: (18)F-D4-FCH is a safe PET radiotracer with a dosimetry profile comparable to other common (18)F PET tracers. These data support the further development of (18)F-D4-FCH for clinical imaging of choline metabolism.

2H2O-based high-density lipoprotein turnover method for the assessment of dynamic high-density lipoprotein function in mice.

OBJECTIVE: High-density lipoprotein (HDL) promotes reverse cholesterol transport from peripheral tissues to the liver for clearance. Reduced HDL-cholesterol (HDLc) is associated with atherosclerosis; however, as a predictor of cardiovascular disease, HDLc has limitations because it is not a direct marker of HDL functionality. Our objective was to develop a mass spectrometry-based method for the simultaneous measurement of HDLc and ApoAI kinetics in mice, using a single (2)H2O tracer, and use it to examine genetic and drug perturbations on HDL turnover in vivo. APPROACH AND RESULTS: Mice were given (2)H2O in the drinking water, and serial blood samples were collected at different time points. HDLc and ApoAI gradually incorporated (2)H, allowing experimental measurement of fractional catabolic rates and production rates for HDLc and ApoAI. ApoE(-/-) mice displayed increased fractional catabolic rates (P<0.01) and reduced production rates of both HDLc and ApoAI (P<0.05) compared with controls. In human ApoAI transgenic mice, levels and production rates of HDLc and human ApoAI were strikingly higher than in wild-type mice. Myriocin, an inhibitor of sphingolipid synthesis, significantly increased both HDL flux and macrophage-to-feces reverse cholesterol transport, indicating compatibility of this HDL turnover method with the macrophage-specific reverse cholesterol transport assay. CONCLUSIONS: (2)H2O-labeling can be used to measure HDLc and ApoAI flux in vivo, and to assess the role of genetic and pharmacological interventions on HDL turnover in mice. Safety, simplicity, and low cost of the (2)H2O-based HDL turnover approach suggest that this assay can be scaled for human use to study effects of HDL targeted therapies on dynamic HDL function.

Water turnover in children and young adults.

Water homeostasis is essential for life and optimal function and considerable interest surrounds the issue of recommendations for water consumption in healthy individuals. Objective data on water turnover in free-living individuals are limited, however. The aim of the present work was to measure water turnover in children and young adults using isotopically labeled water to provide objective data on magnitude and variability in relation to body weight, fat-free mass and physical activity level. Water turnover was measured by deuterated water dilution in 91 healthy children (40 boys, 51 girls; age 5-14 years) and 109 healthy young adults (80 women, 29 men; age 18-27 years) with a wide range of body mass index (13.3-51.8 kg/m(2)) and percent body fat (6.1-59.3%). Total energy expenditure (TEE) and resting metabolic rate were measured by the doubly labeled water technique and indirect calorimetry, respectively. Water turnover was 1.77 ± 0.57 (SD), 1.79 ± 0.44, 2.85 ± 0.82, and 3.90 ± 0.81 L/day in girls, boys, women, and men, respectively. Water turnover indexed to body surface area did not differ significantly between girls and women but was higher in men than boys. Water turnover indexed to TEE was 0.8 mL/kcal in girls and boys and 1.0 mL/kcal in women and men. This study provides objective data on water turnover for children and young adults in a temperate climate and shows that anthropometric parameters can account for the variation between girls, boys and women but not between these groups and the more active men.

[18F]fluoromethyl-[1,2-2H4]-choline: a novel radiotracer for imaging choline metabolism in tumors by positron emission tomography.

Current radiotracers for positron emission tomography imaging of choline metabolism have poor systemic metabolic stability in vivo. We describe a novel radiotracer, [(18)F]fluoromethyl-[1,2-(2)H(4)]-choline (D4-FCH), that employs deuterium isotope effect to improve metabolic stability. D4-FCH proved more resistant to oxidation than its nondeuterated analogue, [(18)F]fluoromethylcholine, in plasma, kidneys, liver, and tumor, while retaining phosphorylation potential. Tumor radiotracer levels, a determinant of sensitivity in imaging studies, were improved by deuterium substitution; tumor uptake values expressed as percent injected dose per voxel at 60 min were 7.43 +/- 0.47 and 5.50 +/- 0.49 for D4-FCH and [(18)F]fluoromethylcholine, respectively (P = 0.04). D4-FCH was also found to be a useful response biomarker. Treatment with the mitogenic extracellular kinase inhibitor PD0325901 resulted in a reduction in tumor radiotracer uptake that occurred in parallel with reductions in choline kinase A expression. In conclusion, D4-FCH is a very promising metabolically stable radiotracer for imaging choline metabolism in tumors.

Dynamics of glutathione and ophthalmate traced with 2H-enriched body water in rats and humans.

We developed a LC-MS-MS assay of the (2)H labeling of free glutathione (GSH) and bound glutathione [GSSR; which includes all DTT-reducible forms, primarily glutathione disulfide (GSSG) and mixed disulfides with proteins] and ophthalmate (an index of GSH depletion) labeled from (2)H-enriched body water. In rats whose body water was 2.5% (2)H enriched for up to 31 days, GSH labeling follows a complex pattern because of different rates of labeling of its constitutive amino acids. In rats infused with [(13)C(2),(15)N-glycine]glutathione, the rate of appearance of plasma GSH was 2.1 micromol.min(-1).kg(-1), and the half-life of plasma GSH/GSSR was 6-8 min. In healthy humans whose body fluids were 0.5% (2)H enriched, the (2)H labeling of GSH/GSSR and ophthalmate can be precisely measured after 4 h, with GSH being more rapidly labeled than GSSR. Since plasma GSH/GSSR derives mostly from liver, this technique opens the way to 2) probe noninvasively the labeling pattern and redox status of the liver GSH system in humans and 2) assess the usefulness of ophthalmate as an index of GSH depletion.

Uptake of 3H-cAMP by retinal pigment epithelium isolated from bluegill sunfish (Lepomis macrochirus).

BACKGROUND: In bluegill sunfish, the melanin-containing pigment granules of the retinal pigment epithelium undergo cyclic movements in response both to ambient lighting and circadian cues. Pigment granules aggregate into the cell body at night (in the dark), and disperse into apical processes during the day (in the light). Regulation of pigment granule aggregation in a number of fishes depends on modulating the intracellular levels of cyclic adenosine monophosphate. RESULTS: Here we show isolated RPE takes up cyclic adenosine monophosphate (cAMP) in a saturable manner, exogenously applied cAMP induces pigment granule aggregation in retinal pigment epithelium isolated from bluegill, and aggregation induced in this manner is inhibited by treatment with probenecid, an organic anion transport inhibitor. CONCLUSION: Our results raise the possibility that cAMP functions as a messenger secreted from the neural retina to signal darkness to the RPE, which takes it up. It further suggests that organic anion transport systems are the route by which cAMP crosses RPE cell membranes since probenecid inhibits extracellular cAMP from causing pigment granule aggregation.

Comparison of monoamine oxidase a in peripheral organs in nonsmokers and smokers.

UNLABELLED: Smokers have reduced levels of brain monoamine oxidase A (MAO A) leading to speculation that MAO A inhibition by tobacco smoke may underlie some of the neurophysiologic effects of smoking. Because smoking exposes peripheral organs as well as the brain to MAO A-inhibitory compounds, we determined whether smokers would also have reduced MAO A in peripheral organs. METHODS: We measured MAO A in peripheral organs in a group of 9 smokers and compared it with a group of nonsmokers studied previously. MAO A was measured using PET and serial scans with the MAO A-specific radiotracers (11)C-clorgyline and deuterium-substituted (11)C-clorgyline ((11)C-clorgyline-D2) using the deuterium isotope effect to assess binding specificity. The time course of radiotracer in the arterial plasma was also measured and data from the tissue time-activity curves and the arterial input function were analyzed using a 3-compartment model to estimate k(3), which represents the rate-limiting step for the irreversible binding of labeled clorgyline to MAO A. RESULTS: Tracer uptake at plateau was reduced with deuterium substitution for the heart, lungs, and kidneys, indicating specificity for MAO. There was no difference in organ uptake at plateau between nonsmokers and smokers though, for the smokers, the efflux of tracer from peak uptake to plateau was slower for the lungs. The area under the time-activity curve for the arterial plasma was also significantly reduced for smokers versus nonsmokers and the reduction occurred in the first few minutes after radiotracer injection. Smokers had an approximately 50% reduction in k(3) when compared with nonsmokers; however, k(3) did not differ for nonsmokers and smokers for the heart and the kidneys. CONCLUSION: Because MAO A breaks down serotonin, norepinephrine, dopamine, and tyramine, and because the lung is a major metabolic organ in degrading some of these substances, reduced lung MAO A may contribute to some of the physiologic effects of smoking. This study also revealed that the concentration of the radiotracers in the arterial plasma is significantly lower for the smoker versus the nonsmoker and that this appears to be caused in part by retention of the radiotracer in lungs. If this is generally true for other substances that are administered intravenously, then this needs to be considered as a variable that may contribute to different short-term behavioral responses to intravenously administered drugs for nonsmokers versus smokers.

Pharmaco-thermodynamics of deuterium-induced oedema in living rat brain via 1H2O MRI: implications for boron neutron capture therapy of malignant brain tumours.

In addition to its common usage as a tracer in metabolic and physiological studies, deuterium possesses anti-tumoural activity and confers protection against gamma-irradiation. A more recent interest in deuterium emanates from the search for alternatives capable of improving neutron penetrance whilst reducing healthy tissue radiation dose deposition in boron neutron capture therapy of malignant brain tumours. Despite this potential clinical application, deuterium induces brain oedema, which is detrimental to neutron capture therapy. In this study, five adult male rats were titrated with deuterated drinking water while brain oedema was monitored via water proton magnetic resonance imaging. This report concludes that deuterium, as well as deuterium-induced brain oedema, possesses a uniform brain bio-distribution. At a steady-state blood fluid deuteration value of 16%, when the deuterium isotope fraction in drinking water was 25%, a mean oedematous volume change of 9 +/- 2% (p-value <0.001) was observed in the rat brain-this may account for neurological and behavioural abnormalities found in mammals drinking highly deuterated water. In addition to characterizing the pharmaco-thermodynamics of deuterium-induced oedema, this report also estimates the impact of oedema on thermal neutron enhancement and effective dose reduction factors using simple linear transport calculations. While body fluid deuteration enhances thermal neutron flux penetrance and reduces dose deposition, oedema has the opposite effect because it increases the volume of interest, e.g., the brain volume. Thermal neutron enhancement and effective dose reduction factors could be reduced by as much as approximately 10% in the presence of a 9% water volume increase (oedema).

Surfactant phosphatidylcholine half-life and pool size measurements in premature baboons developing bronchopulmonary dysplasia.

Because minimal information is available about surfactant metabolism in bronchopulmonary dysplasia, we measured half-lives and pool sizes of surfactant phosphatidylcholine in very preterm baboons recovering from respiratory distress syndrome and developing bronchopulmonary dysplasia, using stable isotopes, radioactive isotopes, and direct pool size measurements. Eight ventilated premature baboons received (2)H-DPPC (dipalmitoyl phosphatidylcholine) on d 5 of life, and radioactive (14)C-DPPC with a treatment dose of surfactant on d 8. After 14 d, lung pool sizes of saturated phosphatidylcholine were measured. Half-life of (2)H-DPPC (d 5) in tracheal aspirates was 28 +/- 4 h (mean +/- SEM). Half-life of radioactive DPPC (d 8) was 35 +/- 4 h. Saturated phosphatidylcholine pool size measured with stable isotopes on d 5 was 129 +/- 14 micro mol/kg, and 123 +/- 11 micro mol/kg on d 14 at autopsy. Half-lives were comparable to those obtained at d 0 and d 6 in our previous baboon studies. We conclude that surfactant metabolism does not change during the early development of bronchopulmonary dysplasia, more specifically, the metabolism of exogenous surfactant on d 8 is similar to that on the day of birth. Surfactant pool size is low at birth, increases after surfactant therapy, and is kept constant during the first 2 wk of life by endogenous surfactant synthesis. Measurements with stable isotopes are comparable to measurements with radioactive tracers and measurements at autopsy.

Measurement in vivo of proliferation rates of slow turnover cells by 2H2O labeling of the deoxyribose moiety of DNA.

We describe here a method for measuring DNA replication and, thus, cell proliferation in slow turnover cells that is suitable for use in humans. The technique is based on the incorporation of (2)H(2)O into the deoxyribose (dR) moiety of purine deoxyribonucleotides in dividing cells. For initial validation, rodents were administered 4% (2)H(2)O in drinking water. The proliferation rate of mammary epithelial cells in mice was 2.9% per day and increased 5-fold during pregnancy. Administration of estradiol pellets (0-200 microg) to ovariectomized rats increased mammary epithelial cell proliferation, according to a dose-response relationship up to the 100 microg dose. Similarly, proliferation of colon epithelial cells was stimulated in a dose-response manner by dietary cholic acid in rats. Bromodeoxyuridine labeling correlated with the (2)H(2)O results. Proliferation of slow turnover cells was then measured. Vascular smooth muscle cells isolated from mouse aorta divided with a half-life in the range of 270-400 days and die-away values after (2)H(2)O wash-out confirmed these slow turnover rates. The proliferation rate of an adipocyte-enriched fraction from mouse adipose tissue depots was 1-1.5% new cells per day, whereas obese ad libitum-fed obob mice exhibited markedly higher fractional and absolute proliferation rates. In humans, stable long-term (2)H(2)O enrichments in body water were achieved by daily (2)H(2)O intake, without toxicities. Labeled dR from fully turned-over blood cells (monocytes or granulocytes) exhibited a consistent amplification factor relative to body (2)H(2)O enrichment ( approximately 3.5-fold). The fraction of newly divided naive-phenotype T cells after 9 weeks of labeling with (2)H(2)O was 0.056 (CD4(+)) and 0.043 (CD8(+)) (replacement rate <0.1% per day). In summary, (2)H(2)O labeling of dR in DNA allows safe, convenient, reproducible, and inexpensive measurement of cell proliferation in humans and experimental animals and is well suited for slow turnover cells.

Partition coefficients between human blood or adipose tissue and air for aromatic solvents.

OBJECTIVES: The partitioning of lipophilic toxicants into blood and into adipose tissue plays an important role in the physiological distribution and toxicology of these substances. The partition coefficients between blood and air and adipose tissue and air were determined for widely used aromatic solvents in an in vitro test system using human tissue samples. METHODS: Samples of whole venous blood (N = 35) were drawn from 10 subjects. In addition, samples of perirenal and epididymal adipose tissue were obtained from F344 rats, along with subcutaneous, omental, or inguinal adipose tissue from 43 patients who had undergone surgery. Portions of each tissue were injected into vials for equilibration with atmospheres containing deuterated and nondeuterated organic solvents. Gas chromatographic headspace analysis was then used to determine the partition coefficients between blood and air and adipose tissue and air. RESULTS: The mean partition coefficients between human blood and air or adipose tissue and air were 334 (SE 11) (adipose tissue) for benzene; 1764 (SE 49) (adipose tissue) for ethylbenzene; 3184 (SE 84) (adipose tissue) for styrene; 18.3 (SE 0.24) (blood) and 962 (SE 32) (adipose tissue) for toluene; 35.2 (SE 0.45) (blood) and 2460 (SE 63) (adipose tissue) for O-xylene; 31.9 (SE 0.45) (blood) and 1919 (SE 53) (adipose tissue) for m-xylene; and 39.0 (SE 0.70) (blood) and 2019 (SE 102) for p-xylene. Regression analyses revealed coefficients of determination of 0.88 (human) and 0.98 (rat) between blood and air and log tissue and air. A value of 0.98 was found for partition coefficients between rat and human adipose tissue. CONCLUSIONS: The partition coefficients between blood and air and adipose tissue and air were strongly correlated. The partitioning of aromatic solvents into rat adipose tissue is predictive of partitioning into human adipose tissue.

2H-nuclear magnetic resonance imaging of tumor blood flow: spatial and temporal heterogeneity in a tissue-isolated mammary adenocarcinoma.

2H-Nuclear magnetic resonance imaging of deuteron accumulation in tissue following an i.v. bolus of deuterium oxide provides a noninvasive means of constructing maps of tissue perfusion. With a measured arterial input function and a simple model for tissue-capillary exchange, these data can provide quantitative estimates of local flow. This technique was tested in rat brain and then applied to the study of spatial heterogeneity and temporal variation of blood flow in the tissue-isolated R3230AC mammary adenocarcinoma. Global flow from the brain averaged 0.96 ml/min.g, in good agreement with results obtained from other methods; the perfusion of brain was relatively homogeneous. Global tumor blood flow averaged 0.32 ml/min.g, ranging from 0.11 to 0.96 ml/min.g. Imaging revealed variations in perfusion both within and between the tumors that far exceeded those expected from brain flow heterogeneity and uncertainty in the flow estimates. By obtaining repeated flow images at 30-min intervals, it was possible to show that the regional blood flow shifted with time in single pixels and in multipixel regions. These experiments show that 2H-nuclear magnetic resonance may be useful in obtaining noninvasive and quantitative measurement of temporal blood flow changes in a solid tumor in vivo.

Quantitation of positional isomers of deuterium-labeled glucose by gas chromatography/mass spectrometry.

A method for determining the site and extent of deuterium (D) labeling of glucose by GC/MS and mass fragmentography was developed. Under chemical and electron impact ionization, ion clusters m/z 328, 242, 217, 212, and 187 of glucose aldonitrile pentaacetate and m/z 331 and 169 of pentaacetate derivative were produced. From the mass spectra of 13C- and D-labeled reference compounds, glucose carbon and hydrogen (C-H) positions included in these fragments were deduced to be m/z 328 = C1-C6, 2,3,4,5,6,6-H6; m/z 331 = C1-C6, 1,2,3,4,5,6,6-H7; m/z 169 = C1-C6, 1,3,4,5,6,6-H6; m/z 187 = C3-C6, 3,4,5,6,6-H5; m/z 212 = C1-C5, 2,3,4,5-H4; m/z 217 = C4-C6, 4,5,6,6-H4; and m/z 242 = C1-C4, 2,3,4-H3. After correction for isotope discrimination and deuterium-hydrogen exchange, the D enrichment of these fragments can be quantitated using selective ion monitoring, and the D enrichment of all C-H positions can be obtained by the difference in enrichment of the corresponding ion pairs. The validity of this approach was tested by examining D enrichment of known mixtures of 1-d1-, 2-d1-, 3-d1-, and 5,6,6-d3-glucose with unlabeled glucose and D enrichment of perdeuterated glucose using these fragments. This method was used to determine deuterium incorporation in C1 through C6 of blood glucose in fasted (24 h) rats infused with deuterated water. The distribution of deuterium was similar to that found by Postle and Bloxham (1980, Biochem. J. 192, 65-73). Approximately one deuterium atom was incorporated into C5 and only 75% deuterium atom was incorporated into C2. The enrichment of C2 and C6 of glucose relative to that of water indicated that 74 +/- 9% of plasma glucose was newly formed 4 h after the onset of deuterium infusion, and gluconeogenesis accounted for about 76 +/- 7% of the glucose 6-phosphate flux.