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At least 433 records · Page 24Linked to original sources

Kinetic analyses of transmitter release in neuromuscular transmission.

A majority of transmitter quanta in the nerve terminal is in a large pool of store (S), which can be utilized for release only after transformation into activated quanta (n) via two intermediate states called available quanta (A) and releasable quanta (N). Mobilization is a collective term applicable for aggregates of S----A, A----N and N----n conversions. In the present article, various electrophysiological procedures for kinetic analyses of the transmitter release in neuromuscular transmission were discussed to elucidate this not well understood process of mobilization. Especially, frequency augmentation, tetanic rundown and depression, and recovery from depression experiments were proposed to be very useful tools in identifying the drug effect on the mobilization process. Since d-tubocurarine, 2-(4-phenylpiperidino)cyclohexanol (AH5183) and Ba ions satisfied the above three criteria of drug action on mobilization, these were concluded to affect the mobilization of transmitter in neuromuscular transmission.

Animals↗

Dielectric spectroscopy and electrophoretic mobility measurements interpreted with the standard electrokinetic model.

We report results from complementary electrokinetic measurements-dielectric relaxation and electrophoretic mobility-undertaken to test the applicability of the standard electrokinetic theory with a model system. Dielectric spectra were obtained at frequencies between 1 kHz and 40 MHz with a new, two-electrode cell design [Hollingsworth and Saville, J. Colloid Interface Sci. 257 (2003) 65-76]; mobility data were acquired with an electrophoretic light scattering instrument. Data from the two-electrode cell were collected at different electrode separations and interpreted with newly developed procedures to remove the influence of electrode polarization. Methodology A employs extrapolation to infinite electrode separation to compute the dielectric constant and conductivity as functions of frequency. The contributions from suspended particles are reported in terms of dielectric constant and conductivity increments. Methodology B uses a theoretical model of electrode polarization and the standard electrokinetic model in a nonlinear regression scheme. Results are presented in several forms: frequency-dependent dielectric constant and conductivity increments, frequency-dependent dielectric constants and conductivities, and the complex dipole coefficient. It is shown that the standard model provides a consistent methodology for interpreting particle behavior; zeta-potentials inferred from mobility and dielectric relaxation agree to within experimental error. Moreover, the cell design and interpretation are straightforward and provide relatively simple ways to obtain complementary measurements over a wide frequency range. The results unambiguously show that electrokinetic character of this dispersion follows the standard model.

Journal Article↗

Wireless access to a pharmaceutical database: a demonstrator for data driven Wireless Application Protocol (WAP) applications in medical information processing.

BACKGROUND: The Wireless Application Protocol technology implemented in newer mobile phones has built-in facilities for handling much of the information processing needed in clinical work. OBJECTIVES: To test a practical approach we ported a relational database of the Danish pharmaceutical catalogue to Wireless Application Protocol using open source freeware at all steps. METHODS: We used Apache 1.3 web software on a Linux server. Data containing the Danish pharmaceutical catalogue were imported from an ASCII file into a MySQL 3.22.32 database using a Practical Extraction and Report Language script for easy update of the database. Data were distributed in 35 interrelated tables. Each pharmaceutical brand name was given its own card with links to general information about the drug, active substances, contraindications etc. Access was available through 1) browsing therapeutic groups and 2) searching for a brand name. The database interface was programmed in the server-side scripting language PHP3. RESULTS: A free, open source Wireless Application Protocol gateway to a pharmaceutical catalogue was established to allow dial-in access independent of commercial Wireless Application Protocol service providers. The application was tested on the Nokia 7110 and Ericsson R320s cellular phones. CONCLUSIONS: We have demonstrated that Wireless Application Protocol-based access to a dynamic clinical database can be established using open source freeware. The project opens perspectives for a further integration of Wireless Application Protocol phone functions in clinical information processing: Global System for Mobile communication telephony for bilateral communication, asynchronous unilateral communication via e-mail and Short Message Service, built-in calculator, calendar, personal organizer, phone number catalogue and Dictaphone function via answering machine technology. An independent Wireless Application Protocol gateway may be placed within hospital firewalls, which may be an advantage with respect to security. However, if Wireless Application Protocol phones are to become effective tools for physicians, special attention must be paid to the limitations of the devices. Input tools of Wireless Application Protocol phones should be improved, for instance by increased use of speech control.

Clinical Pharmacy Information Systems↗

Application of teem-test for investigations of cellular immune phenomena in multiple sclerosis.

Some evidence is presented for usableness of tanned erythrocytes in electrophoretic mobility (TEEM)-test. Two possibilities of application of TEEM-test for immunological investigation in multiple sclerosis are discussed: detection of lymphocyte sensitization against a soluble antigen (3 M KCl extracted) derived from a normal brain and measurement of mixed lymphocyte reactin (MLR) after a short-time lymphocyte culture. Results show some connection between autosensitization (TEEM-test using normal tissue antigen) and predisposition (TEEM-MLR-test).

Antigens↗

A method to relate steady-state ionic currents, conductances, and membrane potential in ion exchange membranes with unknown thermodynamic properties.

A method is presented by which the steady-state properties of an homogeneous, permselective membrane at uniform temperature can be predicted without knowledge of its thermodynamic properties other than assuming that they are functions only of local mole fractions in the membrane. By making this assumption, it is shown how the ionic conductances can be calculated at any point in the membrane from two sets of measurements, (a) R(symm), the steady-state resistance of the membrane measured between identical solutions and (b) V(0), the potential difference between nonidentical solutions for zero current. These two parameters are measured at different external solution compositions (e.g. a varying sodium-potassium ratio ranging from zero to infinity). From these measurements it is shown how the flux equations may be integrated without a knowledge of mobilities, activity coefficients, and other interior membrane parameters. The application of the method to fixed site membranes with variable mobilities is described and the theory for this particular case has also been verified experimentally in glass membranes.1 A possible application to biological membranes is discussed and a comparison is made between the present treatment and previous treatments used to calculate the steady-state properties of cell membranes, notably the theory of Teorell, Meyer, and Sievers and the constant field theory.

Cell Membrane↗

On-line measurement data of wastewater systems via WAP mobile phones.

In order to support the operation of wastewater systems a system was developed which allows us to access plant data by standard mobile devices such as WAP mobile phones. This system is suited complement the standard application of alarm and message systems based for example on SMS or pager services. This technology provides useful options for mobile remote monitoring and remote control of automated plants. This technology is particularly appropriate for the use in remote facilities where no staff is available. The technology has been implemented succesfully and shows how standard IT and Internet technologies can be utilised to support the operation of spatially distributed plants with reasonable effort. Two implementations are presented which access plant data via WAP mobile phones and via mobile pocket PCs. First application experiences are presented.

Automation↗

Mobility of synaptic vesicles in different pools in resting and stimulated frog motor nerve terminals.

We used fluorescence recovery after photobleaching (FRAP) to measure the mobility of synaptic vesicles in frog motor nerve terminals. Vesicles belonging to the recycling pool or to the reserve pool were selectively labeled with FM1-43. In resting terminals, vesicles in the reserve pool were immobile, while vesicles in the recycling pool were mobile. Nerve stimulation increased the mobility of reserve pool vesicles. Treatment with latrunculin A, which destroyed actin filaments, had no significant effect on mobility, and reducing the temperature likewise had little effect, suggesting that recycling pool vesicles move by simple diffusion. Application of okadaic acid caused vesicle mobility in both pools to increase to the same level. We could model these and others' results quantitatively by taking into account the relative numbers of mobile and immobile vesicles in each pool, and vesicle packing density, which has a large effect on mobility.

Animals↗

Mathematical representation of analyte's capacity factor in binary solvent mobile phases using the Jouyban-Acree model.

Applicability of a solution model, namely the Jouyban-Acree model, for mathematical representation of capacity factors of phenobarbital, phenytoin and carbamazepine in mobile phases containing water and the organic modifiers: methanol, acetonitrile, acetone and tetrahydrofuran and also a number of data sets collected from the literature has been shown. The accuracy of the proposed model is compared with those of the linear model and the quadratic equation using average percentage deviation (APD) as an accuracy criterion. The obtained mean and standard deviation of APDs of the Jouyban-Acree, linear and quadratic models are 8.1 +/- 8.4, 25.2 +/- 18.0 and 14.5 +/- 16.2%, respectively. The results showed that the Jouyban-Acree model provided more accurate calculations than the previously published models and the mean differences were statistically significant (p < 0.002).

Algorithms↗

[Application of electroosmotic pump on micro column liquid chromatography].

An electroosmotic pump(EOP) was designed and evaluated, which could replace the mechanical pump. The EOP could generate 2.0 MPa-6.0 MPa output pressure and tens of nL/min-3 microL/min flow rate. A test mixture containing naphthalene, anthracene and phenanthrene was separated on a 14 cm x 320 microns i.d., 5 microns, C18 micro column with acetonitrile/water as a mobile phase, which demonstrated the applicability of the EOP.

Anthracenes↗

KAMEDO report no. 80: train accident in England, 1999.

The train crash that occurred in London in 1999 resulted in 31 dead and almost 300 injured persons. Mobilized resources allowed for the application of normal treatment principles. Available resources were in excess of what was needed. The procedures implemented were judged as adequate. Responses followed the management plan formulated over many years and experiences. The rotating command procedures used worked well. Multiple communications systems were used, including landline telephones, mobile telephones, and radios. Plans should include caring for both adults and children. Well-planned psychosocial services and functional compute services are essential components.

Accidents↗

DNA-mobility shift assay and the detection of anti-DNA IgG in systemic lupus erythematosus patients.

Although the presence of antibodies against double-stranded (ds) DNA is highly specific of systemic lupus erythematosus (SLE), it is not detected in all SLE patients, perhaps due to a lack of sensitivity of the tests routinely used to assay anti-(ds) DNA. Looking for an alternative assay, this study explored the applicability of a DNA-mobility shift assay for the detection of anti-(ds) DNA; furthermore, the study compared the use of Salmonella typhimurium DNA with that of calf thymus DNA in the assay. After electrophoresis, samples containing S. typhimurium DNA and IgG from SLE sera showed marked alterations in DNA electrophoretic mobility when compared to DNA alone. In our sampling, SLE patients who tested negative for anti-(ds) DNA antibodies with routinely used assays such as Crithidia luciliae immunofluorescence test, radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA), tested positive for anti-(ds) DNA with the DNA mobility shift assay using S. typhimurium DNA. Incubation with IgG from control sera in the same proportions as above did not affect S. typhimurium DNA electrophoretic mobility. When S. typhimurium DNA was replaced by calf thymus DNA, the effect on the DNA mobility was less pronounced and less reliable. These results indicated that a DNA-mobility shift assay would be a useful alternative for the unequivocal detection of abnormal titers of anti-(ds) DNA antibodies. Furthermore, data indicated a greater ability of the IgG from SLE patients to form complexes with S. typhimurium DNA than with calf thymus DNA, suggesting an alternative testing DNA which may lead to a more sensitive anti-(ds) DNA detection.

Antibodies, Antinuclear↗

Acid-base equilibria of polyvalent electrolytes and theoretical description of polyelectrolyte behavior in electrokinetic separations.

The problem of the theoretical description of the dissociation of polyvalent electrolytes is considered. It is shown that the traditional model which assumes some constant microstate mobility values may have limited applications, since for each microstate the rate of conversion into other states is strongly dependent on pH and thus it may often become comparable with the characteristic times of other important processes (ionic atmosphere relaxation, biopolymer acceleration by electric field). The question of correct modelling of the electrophoretic flux, electrophoretic mobility and conductivity is discussed.

Biopolymers↗

Mobilization of PAH and PCB from contaminated soil using a digestive tract model.

Environmental contaminants are mainly incorporated by ingestion. In general only those contaminants mobilized by the digestive juices are available for absorption in the digestive tract, while pollutants still fixed to indigestible particles leave the body without any effect. To evaluate the different health risks arising from the ingestion of individual types of polluted soil or other materials, we developed an in vitro test system which simulates the transition of pollutants from contaminated materials into digestive juices by means of a standardized artificial gastro-intestinal model. The test system simulates the influence of the acidic environment of the stomach (gastric model) followed by the neutral or slightly alkaline environment of the small intestine (gastro-intestinal model). Investigations on small amounts of polluted soil, sewage sludge, asphalt, metal scrap and blast sand showed that the mobilization of polycyclic aromatic hydrocarbons (PAH) and polychlorinated biphenyls (PCB) by artificial gastric juice reaches 3% up to 22% of the pollutant concentration introduced into the test system. Elutions of the contaminated materials under gastric and subsequently under intestinal conditions with bile concentrations of 3 g/l resulted in PAH- and PCB-mobilizations in the range of 5% up to 40%. The degree of mobilization depends considerably on supplementary food material added to the test system. Lyophilized milk increased the fraction of mobilized PAH and PCB to 40%-85%. Application of the test system on 22 different contaminated soils showed that the mobilization of PAH under gastro-intestinal conditions with the addition of lyophilized milk ranged from 7% up to 95%, and the mobilization of PCB ranged from 32% up to 83%. This indicates that the test system can be a useful tool for evaluating the individual health risks arising from polluted soil or other materials.

Animals↗

Clinical use of a non-isocentric C-arm unit for on-line filmless reconstruction of brachytherapy applicators.

PURPOSE: In this paper it is described how a mobile non-isocentric C-arm can be used to reconstruct brachytherapy applicators using an 'isocentric' imaging set-up without using an orthogonal reconstruction box. METHODS: The images are on-line digitally transferred to the treatment planning system. In order to determine the physical dimensions of the C-arm a simple method is presented that makes use of the relation between the magnification factor and the translational degrees of freedom of the C-arm. A phantom has been used to determine the overall reconstruction accuracy. RESULTS: The accuracy in the reconstruction of the distance between two points is better than 2 mm when using radiographs. If digital images are used the maximum error in reconstructed distances equals 3.6 mm for points located in the corners of the field of view, whereas in the central part of the field the errors are less than 2 mm.

Brachytherapy↗

Tracking chromaffin granules on their way through the actin cortex.

Quantitative time-lapse evanescent-wave imaging of individual fluorescently labelled chromaffin granules was used for kinetic analysis of granule trafficking through a approximately 300-nm(1/e2) optical section beneath the plasma membrane. The mean squared displacement (MSD) was used to estimate the three-dimensional diffusion coefficient (D(3)). We calculated the granules' speed, frame-to-frame displacement and direction and their autocorrelation to identify different stages of approach to the membrane. D(3) was about 10,000 times lower than expected for free diffusion. Granules located approximately 60 nm beneath the plasma membrane moved on random tracks (D(3) approximately 10(-10) cm(2)s(-1)) with several reversals in direction before they approached their docking site at angles larger than 45 degrees. Docking was observed as a loss of vesicle mobility by two orders of magnitude within <100 ms. For longer observation times the MSD saturated, as if the granules' movement was confined to a volume only slightly larger than the granule. Rarely, the local random motion was superimposed with a directed movement in a plane beneath the membrane. Stimulation of exocytosis selectively depleted the immobile, near-membrane granule population and caused a recruitment of distant granules to sites at the plasma membrane. Their absolute mobility levels were not significantly altered. Application of latrunculin or jasplakinolide to change F-actin polymerisation caused a change in D(3) of the mobile granule population as well as a reduction of the rate of release, suggesting that granule mobility is constrained by the filamentous actin meshwork and that stimulation-dependent changes in actin viscosity propel granules through the actin cortex.

Actins↗

In vivo activity of the cleaved form of soluble urokinase receptor: a new hematopoietic stem/progenitor cell mobilizer.

Cleaved forms of soluble urokinase receptor (c-suPAR) have been detected in body fluids from patients affected by various tumors. We recently reported increased c-suPAR levels in sera of healthy donors during granulocyte colony-stimulating factor (G-CSF)-induced mobilization of CD34(+) hematopoietic stem cells (HSC). In vitro, c-suPAR or its derived chemotactic peptide (uPAR(84-95)) stimulated migration of human CD34(+) HSCs and inactivated CXCR4, the chemokine receptor primarily responsible for HSC retention in bone marrow. These results suggested that c-suPAR could potentially contribute to regulate HSC trafficking from and to bone marrow. Therefore, we investigated uPAR(84-95) effects on mobilization of mouse CD34(+) hematopoietic stem/progenitor cells (HSC/HPC). We first showed that uPAR(84-95) stimulated in vitro dose-dependent migration of mouse CD34(+) M1 leukemia cells and inactivated murine CXCR4. uPAR(84-95) capability to induce mouse HSC/HPC release from bone marrow and migration into the circulation was then investigated in vivo. uPAR(84-95) i.p. administration induced rapid leukocytosis, which was associated with an increase in peripheral blood CD34(+) HSCs/HPCs. In vitro colony assays confirmed that uPAR(84-95) mobilized hematopoietic progenitors, showing an absolute increase in circulating colony-forming cells. uPAR(84-95) mobilizing activity was comparable to that of G-CSF; however, neither synergistic nor additive effect was observed in combining the two molecules. These findings show for the first time in vivo biological effects of c-suPAR. Its capability to mobilize HSCs suggests potential clinical applications in HSC transplantation.

Animals↗

[Study on two kinds of antibiotics by the fluorescence thin-layer chromatograph].

Carbostyril medicine is a kind of important chemically synthesized antibiotics, used extensively in the clinic. Ofloxacin (OFXL) and ciprofloxacin (CPLX), being similar in structures, were separated by micellar thin layer chromatography. The 0.0015 mol.L-1 Cetyl trimethyl ammonium bromide (CTAB) and 1% sodium dodecyl sulfate (SDS) (1:1) mixture containing ammonia liquor (1%) and polyamide plates were selected, respectively, as mobile and stationary phases. Various factors affecting the Rf values of drugs on the plates such as the concentration of CTAB, SDS and ammonia liquor, were investigated. Under the appropriate condition, the corresponding Rf is 0.87 and 0.76. The fluorescence determination was carried out at the 280 nm excitation wave-length. Moreover, the stability and the sensibility were measured. The first analytical application of micellar as a mobile phase for the separation of OFLX and CPLX was developed.

Anti-Infective Agents↗

Metribuzin mobility in soil columns as affected by urea fertiliser.

Application of urea fertilisers to soils influences the soil solution characteristics and thus may affect the sorption of soil-applied herbicides. The present investigation reports the influence of urea co-application on sorption and leaching of metribuzin, a triazine herbicide. Urea application at 60 and 120 kg N ha(-1) increased metribuzin sorption in soils over that in untreated natural soil. The Kf (Freundlich adsorption coefficient) values of metribuzin for natural, 60 and 120 kg N ha(-1) treatments were 0.43, 0.46 and 0.84 microg(1 - 1/n) g(-1) ml1/n respectively. Downward mobility of metribuzin was studied in packed soil columns (300 mm length x 59 mm i.d.) at two irrigation intensities, 720 m3 ha(-1) (72 mm) and 3600 m3 ha(-1) (360 mm). After 720 m3 ha(-1) irrigation, metribuzin did not leach out of any column and was not detected in the leachate. Urea amendment slowed the leaching of metribuzin by 20 and 40% in 60 and 120 kg N ha(-1) urea-treated columns respectively. Also, following urea application, greater amounts of metribuzin were retained in the application zone. Upon increasing the irrigation intensity fivefold, urea application did not have any effect on metribuzin mobility, and its breakthrough from both natural and urea-amended columns occurred after 126 mm irrigation. However, there was a marked difference in the maximum concentration of metribuzin in the breakthrough curves obtained from natural and urea-amended columns. The study indicated that co-application of metribuzin and urea fertiliser is a safe practice as far as leaching of herbicide is concerned.

Adsorption↗