Measuring transport of water across the peritoneal membrane

Asghar, Ramzana B.; Diskin, Ann M.; Španěl, Patrik; Smith, David; Davies, Simon

doi:10.1046/j.1523-1755.2003.00253.x

Cited by 15 publications

(18 citation statements)

References 11 publications

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“…We have shown that these requirements are met when the deuterium abundance in the water vapour to be analysed is less than 1000 ppm and using FA-MS in this regime we have made many measurements on TBW in healthy controls and dialysis patients that demonstrate its validity [5][6][7]. But above about 1000 ppm an increasing fraction of the m/z 75 ions become populated with a single D atom in combination with a single 17 O atom and/or two D atoms (see Figure 1 later), and this added complication must then be taken into account in order to obtain accurate deuterium abundances. In some applications of isotopic dilution, restricted volumes of water are involved and this results in a need for measurements of deuterium abundance in water at several thousand parts per million.…”

Section: Sift-ms and Fa-ms For Measurements Of D Abundance In Water Vmentioning

confidence: 99%

“…This allowed the TBW in human subjects to be determined to a comparable precision and accuracy (but see the important proviso and development described in the next paragraph). Much work in the measurement of TBW has been accomplished in collaboration with our clinical colleagues using FA-MS [5][6][7][15][16][17]. However, this method does have a weakness in that by avoiding the upstream mass filter and directly discharging the helium carrier gas/water vapour mixture (which inevitably contains traces of air), ions like NO + and O 2 + are formed in addition to H 3 O + and its hydrates.…”

Section: Sift-ms and Fa-ms For Measurements Of D Abundance In Water Vmentioning

confidence: 99%

“…The abundance of D in the water vapour introduced into the support gas is then obtained by measuring the relative number densities of these isotopologues using quantitative mass spectrometry, as explained later. These isotopologue ions have mass-to-charge ratios (m/z) of 73 (H 9 17 O and for small D enrichments. However, contributions of the last two ions can become important if the number density of the HDO molecules in the analyte vapour is high enough; even isotopologue ions at m/z 76 can become significant at high HDO levels.…”

Section: Introductionmentioning

confidence: 99%

“…For the moment, the method is based on the creation of a swarm of water cluster ions, H 3 ), held in an inert support gas, usually helium, in the presence of water molecules at a constant, known temperature, for time periods sufficient to allow the D, 17 O and 18 O isotopologues of these cluster ions to reach their thermal equilibrium distribution. The abundance of D in the water vapour introduced into the support gas is then obtained by measuring the relative number densities of these isotopologues using quantitative mass spectrometry, as explained later.…”

Section: Introductionmentioning

confidence: 99%

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Determination of the Deuterium Abundances in Water from 156 to 10,000 ppm by SIFT-MS

Španěl

Shestivská

Chippendale

et al. 2011

J. Am. Soc. Mass Spectrom.

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In response to a need for the measurement of the deuterium (D) abundance in water and aqueous liquids exceeding those previously recommended when using flowing afterglow mass spectrometry (FA-MS) and selected ion flow tube mass spectrometry (SIFT-MS) (i.e. 1000 parts per million, ppm), we have developed the theory of equilibrium isotopic composition of the product ions on which these analytical methods are based to encompass much higher abundances of D in water up to 10,000 ppm (equivalent to 1%). This has involved an understanding of the number density distributions of the H, D, In order to investigate the efficacy of this theory, experimental measurements of deuterium abundance in standard mixtures were made by the SIFT-MS technique using two similar instruments and the results compared with the theory. It is demonstrated that the parameterization of experimental data can be used to formulate a simple calculation algorithm for real-time SIFT-MS measurements of D abundance to an accuracy of 1% below 1000 ppm and degrades to about 2% at 10,000 ppm.

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Section: Sift-ms and Fa-ms For Measurements Of D Abundance In Water Vmentioning

confidence: 99%

Section: Sift-ms and Fa-ms For Measurements Of D Abundance In Water Vmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Determination of the Deuterium Abundances in Water from 156 to 10,000 ppm by SIFT-MS

Španěl

Shestivská

Chippendale

et al. 2011

J. Am. Soc. Mass Spectrom.

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“…The mechanisms of peritoneal water transport were explored by combining intraperitoneal volume measurements (13) to determine the net ultrafiltration and reabsorption, with an artificially created deuterated water gradient (HDO), to determine diffusion (14). The different pathways of water transport were investigated by creating conditions of low and high convection through both pore systems (using 1.36 and 3.86% glucose, respectively) and by confining convective flow to the intercellular pores using icodextrin.…”

Section: Methodsmentioning

confidence: 99%

Influence of Convection on the Diffusive Transport and Sieving of Water and Small Solutes across the Peritoneal Membrane

Asghar

Diskin²,

Španěl³

et al. 2005

Journal of the American Society of Nephrology

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The three-pore model of peritoneal membrane physiology predicts sieving of small solutes as a result of the presence of a water-exclusive pathway. The purpose of this study was to measure the diffusive and convective components of small solute transport, including water, under differing convection. Triplicate studies were performed in eight stable individuals using 2-L exchanges of bicarbonate buffered 1.36 or 3.86% glucose and icodextrin. Diffusion of water was estimated by establishing an artificial gradient of deuterated water (HDO) between blood/body water and the dialysate.125 RISA (radio-iodinated serum albumin) was used as an intraperitoneal volume marker to determine the net ultrafiltration and reabsorption of fluid. The mass transfer area coefficient (MTAC) for HDO and solutes was estimated using the Garred and Waniewski equations. The MTAC of HDO calculated for 1.36% glucose and icodextrin were similar (36.8 versus 39.7 ml/min; P ‫؍‬ 0.3), whereas for other solutes, values obtained using icodextrin were consistently higher (P < 0.05). A significant increase in the MTAC of HDO was demonstrated with an increase in the convective flow of water when using 3.86% glucose (mean value, 49.5 ml/min; P < 0.05). MTAC for urea was also increased with 3.86% glucose. The identical MTAC for water using 1.36% glucose and icodextrin indicates that diffusion is predominantly through small pores, whereas the difference in MTAC for the remaining solutes is a reflection of their sieving. The increase in the MTAC of water and urea associated with an increase in convection is most likely due to increased mixing within the interstitium.

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Progress in SIFT‐MS: Breath analysis and other applications

Španěl

Smith

2011

Mass Spectrometry Reviews

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255

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The development of selected ion flow tube mass spectrometry, SIFT-MS, is described from its inception as the modified very large SIFT instruments used to demonstrate the feasibility of SIFT-MS as an analytical technique, towards the smaller but bulky transportable instruments and finally to the current smallest Profile 3 instruments that have been located in various places, including hospitals and schools to obtain on-line breath analyses. The essential physics and engineering principles are discussed, which must be appreciated to design and construct a SIFT-MS instrument. The versatility and sensitivity of the Profile 3 instrument is illustrated by typical mass spectra obtained using the three precursor ions H(3)O(+), NO(+) and O(2)(+)·, and the need to account for differential ionic diffusion and mass discrimination in the analytical algorithms is emphasized to obtain accurate trace gas analyses. The performance of the Profile 3 instrument is illustrated by the results of several pilot studies, including (i) on-line real time quantification of several breath metabolites for cohorts of healthy adults and children, which have provided representative concentration/population distributions, and the comparative analyses of breath exhaled via the mouth and nose that identify systemic and orally-generated compounds, (ii) the enhancement of breath metabolites by drug ingestion, (iii) the identification of HCN as a marker of Pseudomonas colonization of the airways and (iv) emission of volatile compounds from urine, especially ketone bodies, and from skin. Some very recent developments are discussed, including the quantification of carbon dioxide in breath and the combination of SIFT-MS with GC and ATD, and their significance. Finally, prospects for future SIFT-MS developments are alluded to.

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Measuring transport of water across the peritoneal membrane

Cited by 15 publications

References 11 publications

Determination of the Deuterium Abundances in Water from 156 to 10,000 ppm by SIFT-MS

Determination of the Deuterium Abundances in Water from 156 to 10,000 ppm by SIFT-MS

Influence of Convection on the Diffusive Transport and Sieving of Water and Small Solutes across the Peritoneal Membrane

Progress in SIFT‐MS: Breath analysis and other applications

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