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PubMed1999

Fluorescence recovery after photobleaching: a versatile tool for mobility and interaction measurements in pharmaceutical research.

This review introduces the basics of fluorescence recovery after photobleaching (FRAP) from a theoretical and an instrumentational approach. The most interesting and innovative applications with a pharmaceutical point of view are briefly discussed and possible future applications are suggested. These future applications include research on the mobility of macromolecular drugs in macro- or microscopic pharmaceutical dosage forms, mobility, and binding of antitumor drugs in tumor tissue, intracellular trafficking of gene complexes and mobility of drugs in membranes prior to transmembrane penetration. The paper is also intended to be an introductory guideline to those who would like to get involved in FRAP related experimental techniques. Therefore, comprehensive details on different setups and data analysis are given, as well as a brief outline of the problems that may be encountered when performing FRAP. Overall, this review shows the great potential of FRAP in pharmaceutical research. This is complemented by our own results illustrating the possibility of performing FRAP in microscopic dosage forms (microspheres) using a high resolution variant of FRAP.

Cell Membrane↗
PubMed2002

Crack detection by measurement of mechanical impedance of a rotor-bearing system.

Measurements were done to determine the influence of a transverse crack on the mobility of a rotor-bearing system. The results show that the mobility changes substantially due to the presence of crack and follows definite trends with the crack depth and direction of force application. The significant changes in mobility were observed at the natural frequency and at the running frequency of the rotor system. Good agreement between the experimental results and numerical simulations has been observed. The measurement of mobility has been suggested for crack detection and condition monitoring of rotor-bearing systems.

Journal Article↗
PubMed1996

Capillary isoelectric focusing.

Capillary isoelectric focusing is a useful analytical technique for characterization of protein mixtures and determination of protein isoelectric points. It is particularly useful in separation of protein glycoforms (Fig. 5), characterizing protein microheterogeneity (Fig. 6), and resolution of charge variants (Fig. 7). The capillary focusing process is analogous to conventional isoelectric focusing in gels, while the requirement for zone mobilization is unique to the capillary format with on-tube detection. A variety of mobilization methods have been described, and the selection of the mobilization method for a particular application depends on the capillary type, the instrument configuration, and the type of proteins to be analyzed. Capillary IEF is generally successful for proteins with a molecular weight up to about 150,000 that exhibit good solubility in aqueous buffers, but may be unsatisfactory for large or hydrophobic proteins. Because of precipitation and variation in mobilization efficiencies, use of internal standards is recommended in most applications. Capillary IEF can be compared to conventional gel IEF in terms of sample throughput and sensitivity. Conventional gels require approximately 4-6 hr to cast, run, and stain the gel, depending on whether silver or Coomassie staining is used. A typical gel contains 10 sample lanes, yielding a throughput of 25-35 min/sample. Capillary IEF separations (including focusing and mobilization) are typically 15-20 min. The mass sensitivity of conventional gel IEF is 36-47 ng for Coomassie staining and 0.5-1.2 ng for silver staining. In capillary IEF, sensitivity will depend on the volume of sample injected; assuming a capillary with a volume of 100 nl is completely filled with sample prior to focusing, the limit of detection will be approximately 1 microgram/ml or 0.1 ng injected. Thus capillary IEF compares favorably with conventional gel IEF in terms of detectivity and analysis time, and has the additional benefit of complete automation of the process including separation and data reduction.

Buffers↗
PubMed1997

Quality assurance programme applied to mobile C-arm fluoroscopy systems.

The importance of quality assurance (QA) of X-ray equipment in diagnostic imaging departments is well recognised. However, practically no attention has been paid in the literature to the application of QA programmes to mobile C-arm fluoroscopy systems. This equipment is sometimes omitted from these programmes because it is often "off-site" from the main radiological facility and suitable QA protocols are unavailable. The need for QA can be substantiated by the fact that these systems are finding greater clinical use in orthopaedic, vascular and cardiac applications. Hence, there is a growing awareness among users for the need of good image quality and low patient radiation dose. In view of this, the objective of this study was to review the existing literature, design a suitable QA protocol for this equipment and use it to survey 10 C-arms in clinical use. The protocol was designed to address mechanical and electrical safety in addition to radiation safety and image quality. Results indicate substantial performance differences between systems with significant variations in input air kerma rate to the image receptor. The authors believe that such a protocol is necessary with a view to establishing optimal performance levels and assist in the development of suitable "write-off" criteria for such systems.

Equipment Safety↗
PubMed2000

Inositol 1,4,5-trisphosphate-induced Ca2+ release is inhibited by mitochondrial depolarization.

We investigated the consequences of depolarizing the mitochondrial membrane potential (Deltapsi(mit)) on Ca(2+) signals arising via inositol 1,4,5-trisphosphate receptors (InsP(3)R) in hormone-stimulated HeLa cells. Carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) or a mixture of antimycin A+oligomycin were found to rapidly depolarize Deltapsi(mit). Mitochondrial depolarization enhanced the number of cells responding to a brief application of a Ca(2+)-mobilizing hormone and prolonged the recovery of cytosolic Ca(2+) after washout of the hormone; effects consistent with the removal of a passive Ca(2+) buffer. However, with repeated application of the same hormone concentration both the number of responsive cells and peak Ca(2+) changes were observed to progressively decline. The inhibition of Ca(2+) signalling was observed using different Ca(2+)-mobilizing hormones and also with a membrane-permeant Ins(1,4,5)P(3) ester. Upon washout of FCCP, the Ca(2+) signals recovered with a time course similar to the re-establishment of Deltapsi(mit). Global measurements indicated that none of the obvious factors such as changes in pH, ATP concentration, cellular redox state, permeability transition pore activation or reduction in Ca(2+)-store loading appeared to underlie the inhibition of Ca(2+) signalling. We therefore suggest that local changes in one or more of these factors, as a consequence of depolarizing Deltapsi(mit), prevents InsP(3)R activation.

Adenosine Triphosphate↗
PubMed1999

Non-aqueous capillary electrophoresis of drugs: properties and application of selected solvents.

The electrophoretic mobility of selected acidic and basic test solutes have been determined in non-aqueous media prepared by adding various combinations of ammonium acetate, sodium acetate, methane sulphonic acid and acetic acid to acetonitrile, propylene carbonate, methanol, formamide, N-methylformamide, N,N-dimethylformamide and dimethylsulphoxide, respectively. The apparent pH (pH*) of these non-aqueous media have been measured and it was found that pH* is an important factor for the separations in non-aqueous capillary electrophoresis. However, in some solvents the concentration of sodium acetate has a strong influence on the mobility despite very small changes in pH*. Due to the fact that a change in one parameter influences a number of other parameters it is very difficult to conduct systematic studies in non-aqueous media and to compare the migration of the species at fixed pH* values from one solvent to another. Thus pH* is only of value for comparison when used with a specific solvent or solvent mixture. The viscosity of the above-mentioned solvents were measured at various temperatures and means to adjust the viscosity of the non-aqueous media used for capillary electrophoresis are discussed and the separation of ibuprofen and its major metabolites in urine is used as an example.

4-Aminobenzoic Acid↗
PubMed2006

Labelling of human adipose-derived stem cells for non-invasive in vivo cell tracking.

Human adipose-derived stem cells (ASC) can be expanded in an undifferentiated state or differentiated along the osteogenic, chondrogenic, adipogenic, myogenic, endothelial and neurogenic lineage. To test their in vivo and in situ regenerative potential, their fate needs to be traced after application in suitable defect models. Non-invasive imaging systems allow for real time tracking of labelled cells in the living animal. We have evaluated a bioluminescence cell tracking approach to visualise ASC labelled with luciferase in the living animal. Two procedures have been tested to efficiently label human stem cells with a reporter gene (luciferase, green fluorescent protein), namely lipofection with Lipofectamine 2000 and electroporation with a Nucleofector device. With both lipofection and nucleofection protocols, we have reached transfection efficiencies up to 60%. Reporter gene expression was detectable for 3 weeks in vitro and did not interfere with the phenotype and the stem cell properties of the cells. By means of a highly sensitive CCD camera, we were able to achieve real time imaging of cell fate for at least 20 days after application (intravenous, intramuscular, intraperitoneal, subcutaneous) in nude mice. Moreover, we were able to influence cell mobility by choosing different modes of application such as enclosure in fibrin matrix. The optical imaging system with transient transfection is an elegant cell-tracking concept to follow survival and fate of human stem cells in small animals.

Adipose Tissue↗
PubMed1990

[Acid and basic glycoproteins of human saliva. 1. Investigation of glycoproteins of mixed saliva].

By investigating the possibility of the use of elektrophoretic method on the Pol-E agarose film in human mixed saliva, we concluded that these samples should be lyophilised, and the content of proteins of dissolved samples should sorrespond to the concentration which is situated in the normal human serum. The electrophoretic mobility of fractions of mixed saliva in each varied condition (pH = 5,9 pH = 7 pH = 8,6 and pH = 11) of time, of voltage and of different sample volume applicated to the gel. Thet mobility was exclusively anodic. The majority of fractions (5 fractions) xas separated at pH = 11 and a prolonged of electrophoresis. These fractions were acid and of the biggest electrophoretic mobility. According to the place of separation and intensity (in relation to the normal human serum) it was evident that it was question of acid fractions. In mixed saliva characteristic glyco-and phosphoproteins and albumins were registered. This method enables the registration of enumerated fractions, though it is not selective enough for saliva as a biological material.

Electrophoresis, Agar Gel↗
PubMed2001

LC-MS/MS signal suppression effects in the analysis of pesticides in complex environmental matrices.

The application of LC separation and mobile phase additives in addressing LC-MS/MS matrix signal suppression effects for the analysis of pesticides in a complex environmental matrix was investigated. It was shown that signal suppression is most significant for analytes eluting early in the LC-MS analysis. Introduction of different buffers (e.g. ammonium formate, ammonium hydroxide, formic acid) into the LC mobile phase was effective in improving signal correlation between the matrix and standard samples. The signal improvement is dependent on buffer concentration as well as LC separation of the matrix components. The application of LC separation alone was not effective in addressing suppression effects when characterizing complex matrix samples. Overloading of the LC column by matrix components was found to significantly contribute to analyte-matrix co-elution and suppression of signal. This signal suppression effect can be efficiently compensated by 2D LC (LC-LC) separation techniques. The effectiveness of buffers and LC separation in improving signal correlation between standard and matrix samples is discussed.

Buffers↗
PubMed1981

Reversed-phase liquid chromatography for the separation of chloropromazine, imipramine and some of their metabolites.

Reversed-phase liquid chromatography on a C18 bonded silica with water-alcohol mixtures containing decylamine as the mobile phase was investigated for its applicability to the separation of chlorpromazine, imipramine and their metabolites. The addition of decylamine to the mobile phase was found to be necessary in order to obtain symmetrical peaks. The influence of the decylamine and ethanol concentrations and of the pH of the mobile phase was investigated and these parameters were found to be useful for the adjustment of the retention. The phase system developed was found to be suitable for the required separation. The phase system was applied to the analysis of imipramine and its metabolites, desmethylimipramine and didesmethylimipramine, and desmethylchlorpromazine in human plasma.

Chlorpromazine↗
PubMed2003

An application of the XiX decoupling for solid state 13C NMR with mobile samples.

It is very important to obtain higher resolution solid state NMR spectra not only for crystal samples but also for mobile solid samples. We demonstrate that a robust proton decoupling technique, XiX (X inverse-X) decoupling, is very effective in high resolution solid state NMR measurement for mobile samples compared with the usual continuous wave proton decoupling.

Adamantane↗
PubMed2004

Application of the capture-recapture method for estimating number of mobile male sex workers in a port city of Bangladesh.

Male sex workers (MSWs) and sex trades are not new in Bangladesh. Current HIV interventions for MSWs need to be expanded in the major cities, but the number of MSWs needs to be scientifically estimated. Although two-sample capture-recapture surveys are suitable for closed populations, this method was here applied to indirectly estimate the number of mobile MSWs in a conservative social setting, a port city of Bangladesh. Use of the method resulted in an estimation of 248 MSWs (95% confidence interval, 246-250) who picked up clients only at open and known contact venues. This estimate does not, however, reflect the total number as MSWs who worked in unknown hidden venues and could not be reached. Experience suggests that the two-sample capture-recapture method is a simple technique for reliably estimating an unrecognized population. The limitation of this method can be minimized by shortening the time gap between surveys, creating an enabling environment to encounter harassment of MSWs, and offering safety to peer-staff.

Adolescent↗
PubMedDate not supplied

[Application of ESR saturation transfer spectroscopy for the study of molecular mobility of membrane proteins].

The principles and possibilities of saturation transfer spectroscopy--a new approach in the spin label method, enabling one to measure rotational correlation times up to 10(-3) s--are briefly discussed. This approach is applied to the study of the molecular mobility of a membrane protein Ca-dependent ATPase in native sarcoplasmic reticulum membranes and in egg yolk and dipalmitoyllecithin proteoliposomes using spin labels selectively attached to different SH-groups of a protein. The mobility of the labels on two SH-groups was shown to be due to the intramolecular motion of the protein polar head. It is independent of the protein concentration in membrane but is sensitive to substrate binding and to lipid environment. The correlation of this mobility with the ATPase activity was observed when changing lipid environment and temperature.

Animals↗
PubMed2006

Monitoring and telemedicine support in remote environments and in human space flight.

The common features of remote environments are geographical separation, logistic problems with health care delivery and with patient retrieval, extreme natural conditions, artificial environment, or combination of all. The exposure can have adverse effects on patients' physiology, on care providers' performance and on hardware functionality. The time to definite treatment may vary between hours as in orbital space flight, days for remote exploratory camp, weeks for polar bases and months to years for interplanetary exploration. The generic system architecture, used in any telematic support, consists of data acquisition, data-processing and storage, telecommunications links, decision-making facilities and the means of command execution. At the present level of technology, a simple data transfer and two-way voice communication could be established from any place on the earth, but the current use of mobile communication technologies for telemedicine applications is still low, either for logistic, economic and political reasons, or because of limited knowledge about the available technology and procedures. Criteria for selection of portable telemedicine terminals in remote terrestrial places, characteristics of currently available mobile telecommunication systems, and the concept of integrated monitoring of physiological and environmental parameters are mentioned in the first section of this paper. The second part describes some aspects of emergency medical support in human orbital spaceflight, the limits of telemedicine support in near-Earth space environment and mentions some open issues related to long-term exploratory missions beyond the low Earth orbit.

Humans↗
PubMed1976

[Improvement of gynecologic radium therapy through the afterloading method using cesium 137].

For all centers performing gynecological contact irradiation the use of afterloading techniques is urgently required, since they eliminate any radiation exposure to the personnel. The radio-therapist may position and control the empty applicators still free from radiation withoug haste. This procedure diminishes the occurrence of overdosages and underdosages. The care for the patients is possible without radiation exposure, and the morbidity of contact therapy can be reduced by occasional mobilization of the patient, the applicator without sources remaining at its place. The fully automatic apparatus "Curietron" using cesium-137 sources (0.662 MeV gamma emission, half-life period 26.6 years) with an equivalent source activity (factor 2.6) yields the dose distribution demanded in the gynecologic field which in practice is identical to that of Ra-226 (medium gamma emission 1 MeV, half-life period 1620 years). With similar dose distribution, a biological and therapeutical effect alike to Ra-226 may be expected from Cs-137. In comparison with Ra-226, the following advantages of Cs-137 may be mentioned: Lower half-value thickness of 5.5 mm lead (low expenses for radioprotection), less danger with handling (no emanation of radioactive gases), and lower contamination risks in case of breaking. The measured dose distributions at equivalent source activity and similar geometry of the applicators revealed the possibility with regard of all techniques of gynecologic irradiation utilized in our field of arriving at similar relative and absolute dose distributions by means of the Cs-137 afterloading technique. Whilst short-term afterloading irradiation with highly active sources, their radiobiological effectiveness being not yet ascertained, has to be tested at appropriate scientific centers, it is necessary to demand afterloading techniques with dosages and duration of irradiations approved over decades for all centers of gynecological contact therapy because of radiation protection.

Cesium Radioisotopes↗
PubMed2003

Heteroduplex mobility assay for the identification of Listeria sp and Listeria monocytogenes strains: application to characterisation of strains from sludge and food samples.

One hundred and ten Listeria sp. isolates from sewage sludge were identified according to phenotypic and genotypic methods. The Listeria sp. strains isolated from five types of sludge from three sewage treatment plants in Angers (France) and the surrounding area included L. monocytogenes (55.5%), L. innocua (29.1%), L. seeligeri (13.6%) and L. welshimeri (1.8%). The majority of L. monocytogenes strains belonged to serotypes 4b, 1/2b and 1/2a. Moreover, a heteroduplex mobility assay based on the 16S rRNA sequences was tested for its ability to identify the six species of the genus Listeria. This study, performed on 283 Listeria sp. strains from human, food and sewage sludge samples, showed that all the species were distinguishable from one another. L. innocua and L. seeligeri showed respectively three and two distinct banding patterns. Within L. monocytogenes, four groups (I-IV) were defined. The majority of food and environmental isolates were clustered in group I and it is noteworthy that group IV clustered epidemiologic isolates and strains belonging to serotypes 4b, 1/2a and 1/2b.

Animals↗
PubMed2005

Sensitivity enhancement in liquid chromatography/atmospheric pressure ionization mass spectrometry using derivatization and mobile phase additives.

High performance liquid chromatography with atmospheric pressure ionization (API) mass spectrometry has been essential to a large number of quantitative analytical applications for a variety of compounds. Poor detection sensitivity however is a problem observed for a number of analytes because detection sensitivity can be affected by many factors. The two most critical factors are the chemical and physical properties of the analyte and the composition of the mobile phase. In order to address these critical factors which may lead to poor sensitivity, either the structure of the analyte must be modified or the mobile phase composition optimized. The introduction of permanently charged moieties or readily ionized species may dramatically improve the ionization efficiency for electrospray ionization (ESI), and thus the sensitivity of detection. Detection sensitivity may also be enhanced via introduction of moieties with high proton affinity or electron affinity. Mobile phase component modification is an alternative way to enhance sensitivity by changing the form of the analytes in solution thereby improving ionization efficiency. pH adjustment and adduct formation have been commonly used to optimize detection conditions. The sensitivity of detection for analytes in bio-matrices could also be enhanced by decreasing ion-suppression from the matrix through derivatization or mobile phase addition. In this review, we will discuss detection-oriented derivatization as well as the application of mobile phase additives to enhance the sensitivity of detection in liquid chromatograph/atmospheric ionization/mass spectrometry (LC/API/MS), focusing in particular on the applications involving small molecules in bio-matrices.

Alcohols↗