The Experts below are selected from a list of 19830 Experts worldwide ranked by ideXlab platform
Eva Benfeldt - One of the best experts on this subject based on the ideXlab platform.
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application of dermal Microdialysis for the determination of bioavailability of clobetasol propionate applied to the skin of human subjects
Skin Pharmacology and Physiology, 2012Co-Authors: Wai Ling Au, Michael F Skinner, Eva Benfeldt, Roger K Verbeeck, Isadore KanferAbstract:Dermal Microdialysis was used to assess the bioavailability of a topical corticosteroid, clobetasol propionate, following application onto the skin of human subjects. The penetration of clobetasol propionate from a 4% m/v ethanolic solution applied onto 4 sites on one forearm of healthy human volunteers was studied. A lipid emulsion, Intralipid®, was used as the perfusate and linear Microdialysis probes with a 2-kDa cutoff were inserted intradermally at the designated sites. The results indicated that Intralipid could be used as a suitable perfusate for in vivo Microdialysis of this lipophilic drug of interest. Furthermore, the study clearly demonstrated the application of dermal Microdialysis as a valuable tool to assess the bioavailability/bioequivalence of clobetasol propionate penetration into the skin following topical application.
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impact of adult atopic dermatitis on topical drug penetration assessment by cutaneous Microdialysis and tape stripping
Acta Dermato-venereologica, 2009Co-Authors: Patricia Garcia Ortiz, Steen Honoré Hansen, Vinod P. Shah, Torkil Menné, Eva BenfeldtAbstract:Appropriate methodologies for the determination of drug penetration in diseased skin have not yet been established. The aim of this study was to determine the cutaneous penetration of a metronidazole cream formulation in atopic dermatitis, employing dermal Microdialysis and tape strip sampling techniques. Non-invasive measuring methods were used for the quantification of the severity of the dermatitis. Skin thickness and the depth of the Microdialysis probes in the skin were measured by 20 MHz ultrasound scanning. Metronidazole concentration, sampled by Microdialysis, was 2.4-fold higher in the atopic dermatitis compared with uninvolved skin (p<0.001). Tape stripping methodology did not disclose this difference in penetration. Thus, the skin layer of interest and the integrity of the skin barrier should be considered when selecting sampling methodology. Microdialysis sampling is the method of choice whenever the dermis is the target tissue for topical treatment and a skin disease affecting the barrier function is present.
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the effect of irritant dermatitis on cutaneous bioavailability of a metronidazole formulation investigated by Microdialysis and dermatopharmacokinetic method
Contact Dermatitis, 2008Co-Authors: Patricia Garcia Ortiz, Steen Honoré Hansen, Vinod P. Shah, Torkil Menné, Eva BenfeldtAbstract:Background: Determination of drug penetration in diseased skin represents a challenge. Objective: To compare dermal Microdialysis and tape-strip sampling of drug penetration in normal skin and skin with irritant dermatitis. Methods: The two methodologies were employed simultaneously in 16 healthy volunteers. Samples were collected in a study of the penetration of a metronidazole cream formulation (Flagyl® 1%) applied to forearm skin in both areas with irritant dermatitis and normal skin. Barrier perturbation and the depth of Microdialysis probes were quantified by non-invasive bioengineering methods. Results: Microdialysis showed a significant threefold increase in metronidazole penetration in skin with irritant dermatitis compared with unmodified skin. Conversely, the concentration of metronidazole in tape-strip samples was significantly decreased in irritant dermatitis. Conclusion: The selection of sampling methodology should be based on the skin layer of interest as well as the integrity of the skin barrier. Whenever the dermal tissue is the target for topical treatment, Microdialysis sampling should be the method of choice.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenaline-mediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the time-concentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenalinemediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the timeconcentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration. Key words: famciclovir; vasoconstriction; dermal drug concentration; temperature; Microdialysis.
Susan M Lunte - One of the best experts on this subject based on the ideXlab platform.
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a review of Microdialysis coupled to microchip electrophoresis for monitoring biological events
Journal of Chromatography A, 2015Co-Authors: Rachel A Saylor, Susan M LunteAbstract:Microdialysis is a powerful sampling technique that enables monitoring of dynamic processes in vitro and in vivo. The combination of Microdialysis with chromatographic or electrophoretic methods yields along with selective detection methods yields a “separation-based sensor” capable of monitoring multiple analytes in near real time. Analysis of Microdialysis samples requires techniques that are fast (<1 min), have low volume requirements (nL–pL), and, ideally, can be employed on-line. Microchip electrophoresis fulfills these requirements and also permits the possibility of integrating sample preparation and manipulation with detection strategies directly on-chip. Microdialysis coupled to microchip electrophoresis has been employed for monitoring biological events in vivo and in vitro. This review discusses technical considerations for coupling Microdialysis sampling and microchip electrophoresis, including various interface designs, and current applications in the field.
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recent trends in Microdialysis sampling integrated with conventional and microanalytical systems for monitoring biological events a review
Analytica Chimica Acta, 2009Co-Authors: Pradyot Nandi, Susan M LunteAbstract:Microdialysis (MD) is a sampling technique that can be employed to monitor biological events both in vivo and in vitro. When it is coupled to an analytical system, Microdialysis can provide near real-time information on the time-dependent concentration changes of analytes in the extracellular space or other aqueous environments. Online systems for the analysis of Microdialysis samples enable fast, selective and sensitive analysis while preserving the temporal information. Analytical methods employed for online analysis include liquid chromatography (LC), capillary (CE) and microchip electrophoresis and flow-through biosensor devices. This review article provides an overview of Microdialysis sampling and online analysis systems with emphasis on in vivo analysis. Factors that affect the frequency of analysis and, hence, the temporal resolution of these systems are also discussed.
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on line coupling of Microdialysis sampling with microchip based capillary electrophoresis
Analytical Chemistry, 2004Co-Authors: Bryan H Huynh, Barbara A Fogarty, Scott R Martin, Susan M LunteAbstract:Microdialysis sampling is a technique that has been used for in vivo and in vitro monitoring of compounds of pharmaceutical, biomedical, and environmental interest. The coupling of a commercially available Microdialysis probe to a microchip-based capillary electrophoresis (CE) system is described. A continuously flowing dialysate stream from a Microdialysis probe was introduced into the microchip, and discrete injections were achieved using a valveless gating approach. The effect of the applied voltage and Microdialysis flow rate on device performance was investigated. It was found that the peak area varied linearly with the applied voltage. Higher voltages led to lower peak response but faster separations. Perfusion flow rates of 0.8 and 1.0 μL/min were found to provide optimal performance. The on-line Microdialysis/microchip CE system was used to monitor the hydrolysis of fluorescein mono-β-d-galactopyranoside (FMG) by β-d-galactosidase. A decrease of the FMG substrate with an increase in the fluorescei...
L Stahle - One of the best experts on this subject based on the ideXlab platform.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenaline-mediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the time-concentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenalinemediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the timeconcentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration. Key words: famciclovir; vasoconstriction; dermal drug concentration; temperature; Microdialysis.
N Borg - One of the best experts on this subject based on the ideXlab platform.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenaline-mediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the time-concentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration.
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distribution to the skin of penciclovir after oral famciclovir administration in healthy volunteers comparison of the suction blister technique and cutaneous Microdialysis
Acta Dermato-venereologica, 1999Co-Authors: N Borg, Eva Benfeldt, E Gotharson, L Groth, L StahleAbstract:Penciclovir is a drug active against herpes simplex viruses located in the epidermis basal layer. The aim of this study was to compare the suction blister technique and Microdialysis as methods to measure the penciclovir concentration in the skin after a single dose (250 mg) of its prodrug, famciclovir. Suction blister fluid, microdialysates and plasma were sampled from 11 healthy volunteers for 5 h after famciclovir administration. Both the suction blister technique and Microdialysis showed that penciclovir reaches the skin in concentrations sufficient to inhibit herpes virus replication. The maximum concentration in both suction blister fluid and in microdialysate was observed later than in plasma. The Microdialysis concentration was decreased by cooling of the skin surface and by adrenalinemediated vasoconstriction. The Microdialysis recovery of penciclovir was studied with respect to the flow-rate of perfusion medium through the Microdialysis probe. Microdialysis and the suction blister technique can be used to study the timeconcentration profile of penciclovir in the skin and Microdialysis allows a continuous sampling of the drug for a prolonged time after administration. Key words: famciclovir; vasoconstriction; dermal drug concentration; temperature; Microdialysis.
David A Hovda - One of the best experts on this subject based on the ideXlab platform.
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intensive insulin therapy reduces Microdialysis glucose values without altering glucose utilization or improving the lactate pyruvate ratio after traumatic brain injury
Critical Care Medicine, 2006Co-Authors: Paul M Vespa, Robert Boonyaputthikul, David L Mcarthur, Chad Miller, Maria Etchepare, Marvin Bergsneider, Thomas C Glenn, Neil A Martin, David A HovdaAbstract:Objective:To determine that intensive glycemic control does not reduce Microdialysis glucose concentration brain metabolism of glucose.Design:Prospective monitoring followed by retrospective data analysis of cerebral Microdialysis and global brain metabolism.Setting:Single center, academic neurointe
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metabolic crisis without brain ischemia is common after traumatic brain injury a combined Microdialysis and positron emission tomography study
Journal of Cerebral Blood Flow and Metabolism, 2005Co-Authors: Paul M Vespa, David L Mcarthur, Marvin Bergsneider, Thomas C Glenn, Neil A Martin, Nayoa Hattori, Sungcheng Huang, David A HovdaAbstract:Brain trauma is accompanied by regional alterations of brain metabolism, reduction in metabolic rates and possible energy crisis. We hypothesize that Microdialysis markers of energy crisis are present during the critical period of intensive care despite the absence of brain ischemia. In all, 19 brain injury patients (mean GCS 6) underwent combined positron emission tomography (PET) for metabolism of glucose (CMRglu) and oxygen (CMRO(2)) and cerebral Microdialysis (MD) at a mean time of 36 h after injury. Microdialysis values were compared with the regional mean PET values adjacent to the probe. Longitudinal MD data revealed a 25% incidence rate of metabolic crisis (elevated lactate/pyruvate ratio (LPR) > 40) but only a 2.4% incidence rate of ischemia. Positron emission tomography imaging revealed a 1% incidence of ischemia across all voxels as measured by oxygen extraction fraction (OEF) and cerebral venous oxygen content (CvO(2)). In the region of the MD probe, PET imaging revealed ischemia in a single patient despite increased LPR in other patients. Lactate/pyruvate ratio correlated negatively with CMRO(2) (P < 0.001), but not with OEF or CvO(2). Traumatic brain injury leads to a state of persistent metabolic crisis as reflected by abnormal cerebral Microdialysis LPR that is not related to ischemia.
