Microdialysis sampling

Ceschini S, Pietroni P, and Angeletti M. A Multi-Sample Microdialysis Apparatus for Proteins and Nucleic Acids. Prep Biochem Biotech 1996 26(3 4) 189-199. 

Bowel Ischemia Monitoring Using Rapid Sampling Microdialysis Biosensor System... 

B. Rapid Sampling Microdialysis (rsMD) On-Line Assay... 

This study showed that the on-line rapid sampling microdialysis biosensor system can be used to monitor the transit from healthy to ischemic tissue in human bowel and to predict an early ischemic event in the anastomotic segment of porcine animal models. 

The microdialysis sampling process which allows the monitoring of small molecules in circulation within an animal, is an example. An artificial capillary is placed in the tissue region of interest, and a sample is coUected via dialysis. In the case of a laboratory animal such as a rat, a probe is placed in the jugular vein under anesthesia. Elow rates ate of the order of 1 p.L/min. 

T. Foi nstedt, A.-M. Hesselgren and M. Johansson, Chiral assay of atenolol present in microdialysis and plasma samples of rats using chiral CBH as stationaiy phase . Chirality 9 329-334 (1997). 

Ahn JK, Koh EM, Cha HS, Lee YS, Kim J, Bae EK (2008) Role of hypoxia-inducible factor-lalphain hypoxia-induced expressions of IL-8, MMP-1 and MMP-3 in rheumatoid fibroblast-tike synoviocytes. Rheumatology (Oxford) 47(6) 834-839 Ao X, Wang X, Lennartz MR, Loegering DJ, Stenken JA (2006) Multiplexed cytokine detection in microUter microdialysis samples obtained from activated cultured macrophages. J Pharm Biomed Anal 40(4) 915-921... 

Figure 4.8 Noradrenaline concentration in dialysis samples from probes implanted in the rat frontal cortex. Spontaneous efflux of noradrenaline is stable throughout a 4h sampling period ( extended basals ) but is increased markedly when either the noradrenaline reuptake inhibitor, desipramine (5 pM), or the a2-adrenoceptor antagonist, atipamezole (0.5 pM), is infused into the extracellular fluid via the microdialysis probe ( retrodialysis )...

Figure 8.11 Noradrenaline efflux, measured by microdialysis, in the rat frontal cortex and hypothalamus, (a) Repeated exposure to a tone, alone, has no effect on noradrenaline efflux in either brain region, (b) After repeated pairing of the tone with transfer of the rat to a brightly lit (aversive) arena, the sound of the tone alone triggers a significant ( P<0.05, cf last basal sample) increase in noradrenaline efflux in the frontal cortex, but not the hypothalamus. (Based on a figure from McQuade and Stanford 2000)...

Many process mixtures, notably fermentations, require sample preconcentration, microdialysis, microfiltration, or ultrafiltration prior to analysis. A capillary mixer has been used as a sample preparation and enrichment technique in microchromatography of polycyclic aromatic hydrocarbons in water.8 Microdialysis to remove protein has been coupled to reversed phase chromatography to follow the pharmacokinetics of the metabolism of acetaminophen into acetaminophen-4-O-sulfate and acetaminophen-4-O-glucu-ronide.9 On-line ultrafiltration was used in a process monitor for Aspergillus niger fermentation.10... 

Chen, A. and Lunte, C. E., Microdialysis sampling coupled on-line to fast microbore liquid chromatography, /. Chromatogr. A, 691, 29, 1995. 

HPLC coupled to MS was used for the determination of dimethyl xanthine metabolites in plasma.82 There have also been a number of methods published on the use of HPLC with a PDA detector. In 1996, Mei published a method for the determination of adenosine, inosine, hypoxanthine, xanthine, and uric acid in microdialysis samples using microbore column HPLC with a PDA detector.63 In this method, samples were directly injected onto the HPLC without the need for any additional sample treatment. 

Liu, C. Hofstadler, S. A. Bresson, J. A. Udseth, H. R. Tsukuda, T. Smith, R. D. Synder, A. P. On-line dual microdialysis with ESI-MS for direct analysis of complex biological samples and microorganism lysates. Anal. Chem. 1998, 70, 1797-1801. 

Huynh, B.H., Fogarty, B. A., Martin, R.S., Lunte, S.M. (2004). On-line coupling of microdialysis sampling with microchip-based capillary electrophoresis. Anal. Chem. 76, 6440-6447. 

Thompson, J.E., Vickroy, T.W., Kennedy, R.T. (1999). Rapid determination of aspirate enantiomers in tissue samples by microdialysis coupled on-line with capillary electrophoresis. Anal. Chem. 71, 2379-2384. 

Figure 7.4 Dose-response effects of MDMA on extracellular levels of endogenous 5-HT (left panel) and DA (right panel) in rat nucleus accumbens. Male rats undergoing in vivo microdialysis received i.v. injections of 1 and 3 mg/kg MDMA at 0 and 60 min, respectively. Dialysate levels of 5-HT and DA were assayed by HPLC-ECD. Data are mean SEM, expressed as pg/5 pi sample, for N = 6 rats/group. Baseline levels of 5-HT and DA were 0.22 0.03 and 1.44 0.24 pg/5 pi, respectively. Significant with respect to pre-injection control (P < 0.05 Duncan s). See Baumann et al.39 for methods.

A number of recent publications indicate that the antibacterial field has adopted the concept of comparing free drug concentration at the site of action to in vitro drug potency reported as MIC [24-26]. A study of the antibacterial ertapenem in healthy volunteers was carried out to provide support for its use in skin and skin-structure infections [27]. Using microdialysis techniques, unbound drug concentrations in muscle and subcutaneous tissues were sampled at... 

A system based on microdialysis coupled with flow-injection chemiluminescence detection allows for direct sampling of unbound drug without extractive sample preparation [72], A similar approach based on continuous ultrafiltration has also been reported [73]. Modifications designed to overcome challenges of low solubility and high-non-specific binding in the ultrafiltration approach have also been described [74]. 

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