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Modern application of membrane technique in therapeutic and diagnostic medical systems

Ciechanowska A., Sabalińska S., Gutowska M., Wójcicki J. M.

Biocybernetics and Biomedical Engineering

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2008

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Vol. 28, no. 2

21-33

EN

This study presents actually available membrane systems devoted to therapeutic and diagnostic applications. In particular LDL apheresis systems including new Two Stage Membrane System with Recirculation (TSMS) and the microdialysis technique are discussed. Application of the membrane systems to therapeutic purposes with utilization of methods improving the selectivity of LDL cholesterol removal cause decrease of albumin losses. Application of quasi-continuous monitoring using microdialysis technique during intensive treatment provided in some cases a completely new quality data, which may be helpful in the profound understanding of the pathophysiology of the specified diseases.

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Microdialysis technique in monitoring of the patient's metabolic state

Wójcicki J. M., Ciechanowska A., Sabalińska S., Gutowska M.

Biocybernetics and Biomedical Engineering

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2007

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Vol. 27, no. 1-2

53-64

EN

Frequent daily monitoring of the blood glucose level is not an adequately efficient method to maintain long-term normoglycemia and especially to prevent hypoglycemia in many diabetic patients. Continuous glucose measurement systems are currently being developed. The minimally invasive methods are mainly connected with measurements in the interstitial fluid (ISF). With the electroenzymaitic sensor implanted, the ISF glucose continuously reacts with the sensor’s enzyme, and the resulting current is proportional to the glucose concentration. Another possibility can be application of the microdialysis technique (MDS) - technique to monitor the biochemistry of the extracellular space in living tissue. The aim of the study was to review systems for continuous glucose measurements using the microdialysis technique and to present preliminary results of an application of this technique to monitoring of the patient’s metabolic state in ketoacidosis. The first prototype of a system for continuous glucose measurements,was designed and developed in Ulm. Currently, a few similar systems with application of the microdialysis are being developed and tested. The most interesting of them are Accu Chek (Roche Diagnostics), GlucoDay (Menarini) and Gluc-Online (Roche/Disetronic). The MDS technique can be applied, for example, to characterize the patient’s metabolic state in ketoacidosis during application of the standard treatment by measurements of the biochemical parameters, like glucose, lactate and glycerol, in the interstitial fluid. This study was performed by the authors in cooperation with the Clinic of Gastroeneterology and Metabolic Diseases, Medical University in Warsaw. The first presented results indicate that, after the initial hydration, the glycemia, glycerol and lactate levels correlated in a very different way with the reference measurements from blood. No distinct delays between the measurements performed in the studied compartments were observed. It can be stated that the analysis of the courses of the biochemical compounds, involved in the glucose metabolism, in the interstitial and in the blood compartments may be helpful to better understand the pathophysiology of the diabetic ketoacidosis, and consequently, its application can lead to an improvement of the current standard treatment.

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Hyphenated microanalytical systems for on-line and in-situ fractionation and leaching kinetics of heavy metals in solid environmental samples

Frenzel W., Jimoh M., Miro M.

Chemia Analityczna

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2005

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Vol. 50, No. 1

279-299

EN

In this paper two novel methodologies are presented for on-line and in-silu investigation of metal release from solid samples. One is based on continuous propelling suitable leaching agents through the sample held in a microcolumn and on-line detection of the metals released by atomic spectrometric methods (viz. Flame-AAS. ICP-OES and ICP-MS). The main features of this approach are the ability to perform metal fractionation in an automated manner in a couple of minutes with inherent information about the leaching kinetics. The various operating parameters affecting the metal release are discussed and results presented for selected environmental samples. The second method for studying metal release from soil and sediments is based on the incorporation of a capillary microdialysis probe into the solid sample. The analytes dissolved in the interstitial liquid of the solid samples diffuse across the membrane barrier into a continuously flowing perfusion liquid. For sensitive on-line detection of the metals released the system is hyphenated with graphite furnace-AAS. The performance characteristics of the microdialyser are evaluated with respect to metai ion transfer in the absence and presence of complexing agents. The principal limitations of quantification of results are outlined taking into account the particular conditions of microdialytic sampling. Metal release from a laboratory prepared soil column is investigated by two different stimulus-response techniques based on percolation of various leaching agents through the soil column and introduction of the leaching agent via the perfusion liquid (i.e. retro-dialysis), respectively. Comparability of results as obtained in fast column leaching, microdialysis and common batch equilibrium-based metal fractionation procedures are critically assessed. The potential and limitations of the two novel approaches are also discussed with special emphasis to risk assessment associated with heavy metal pollution. Finally, perspectives and future research lines with respect to novel configurations and additional applications are addressed.

PL

Przedstawiono dwie metodologie do badania uwalniania metali ze stałych próbek w układzie on-line i in-situ. Pierwsza polega na ciągłym przepuszczaniu odpowiedniego czynnika ługującego przez próbkę zawarta w mikro kolumnie i wykrywaniu wymytych metali w układzie on-line za pomocą metod spektrometrii atomowej. Istotą tego postępowania jest frakcjonowanie metali w układzie automatycznym z bezpośrednim uzyskaniem informacji o kinetyce ługowania. Przedyskutowano parametry wpływające na uwalnianie metali ?. wybranych próbek środowiskowych. Druga metodologia polega na wprowadzeniu kapilarnej mikrodializy do stałej próbki gleby lub osadu. Anality rozpuszczone w roztworze glebowym stałej próbki dyfundują przez membranę do ciągle przepływającego roztworu. W celu czułego monitorowania uwolnionych metali układ jest sprzężony z grafitowym atomizerem atomowej spektrometrii absorpcyjnej. Charakterystykę działania mikrodializera oszacowano z punktu widzenia przenoszenia metalu w obecności i nieobecności czynników konipleksujących. Głównym ograniczeniem w uzyskiwaniu ilościowych wyników są szczegółowe warunki próbkowania mikrodialitycznego. Uwalnianie metali z laboratoryjnie przygotowanych kolumn glebowych badano dwoma technikami polegającymi na przepuszczaniu różnych czynników ługujących przez kolumnę glebową, atakże na wprowadzeniu czynnika ługującego do cieczy perfuzyjnej (wsteczna dializa). Porównywalność wyników frakcjonowania, otrzymanych na drodze szybkiego ługowania z kolumny, mikrodializy, i zwykłej procedury równowagowej, oszacowano krytycznie. Ograniczenia i możliwości dwóch nowych sposobów postępowania przedyskutowano zwracając szczególną u wagę na aspekty' zanieczyszczenia środowiska metalami. W końcu wskazano perspektywy i kierunki rozwoju nowych układów i ich dodatkowych zastosowań.