scholarly journals The intraoral permeability measurement as a screening for artifact formation by orthodontic products in MRI

2021 ◽  
Author(s):  
Felix H. Blankenstein ◽  
Ulrike Kielburg ◽  
Ludwig Melerowitz ◽  
Daniel Stelmaszczyk
Keyword(s):  
Magnetic Permeability ◽  
Interrater Reliability ◽  
Direct Determination ◽  
Magnetic Flux Density ◽  
Clinical Test ◽  
Permeability Measurement ◽  
Reliable Determination ◽  
Artifact Formation

Abstract Aim Metal dental products lack precautionary statements regarding MR compatibility due to an exemption in the labelling obligation. Hence, it is difficult for radiologists to decide whether to remove fixed metal objects in patients prior to MRI. A solution could be the direct determination of the magnetic permeability (µr) as a decisive material-related predictor of artifact formation and other interactions. Thus, the applicability of an industrially used measurement device as a screening instrument and the relevance of the manufacturer’s application restrictions in vitro and in vivo were tested. Methods Precision and trueness were tested using self-made test objects with different dimensions and different permeability. To clarify whether the measurement results are affected by the remanence (BR) induced in the objects, 28 brackets of different materials were exposed to a weak and a strong external magnetic field and the magnetic flux density before and after these exposures was compared. The clinical test was performed on a volunteer with an orthodontic appliance experimentally composed of brackets with different levels of magnetic permeability (µr). Validity and intra- and interrater reliability were calculated using two rater groups consisting of four dentists and four medical-technical radiology assistants (MTRA), respectively. Results With coefficients of variation below 0.14%, precision was excellent regardless of object surface and size. Trueness was high on objects with µr ≤ 1.002, and decreased with increasing µr, for which size-dependent correction factors were calculated. Intra- and interrater reliability and validity were excellent and independent of professional intraoral manipulation experience. Conclusions The permeability measurement allows for a valid and reliable determination of the magnetizability of intraoral metal objects. When used as a screening tool to detect nonartifact-causing objects, no correction factor needs to be calculated. For the first time, it offers radiologists a decision support for the selective removal of only the highly permeable components of the multiband apparatus.

Direct determination of astragalosides and isoflavonoids from fresh Astragalus membranaceus hairy root cultures by high speed homogenization coupled with cavitation-accelerated extraction followed by liquid chromatography-tandem mass spectrometry

RSC Advances ◽  
2015 ◽  
Vol 5 (44) ◽  
pp. 34672-34681 ◽  
Author(s):  
Jiao Jiao ◽  
Qing-Yan Gai ◽  
Meng Luo ◽  
Xiao Peng ◽  
Chun-Jian Zhao ◽  
...  
Keyword(s):  
High Speed ◽  
Direct Determination ◽  
Metabolic Profiles ◽  
Tandem Mass ◽  
Hairy Root Cultures ◽  
Root Cultures ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

HSH-CAE-LC-MS/MS opened up a new avenue for the direct determination of secondary metabolic profiles from fresh plant in vitro cultures.

scholarly journals 452 DIRECT DETERMINATION OF 17α-HYDROXYLASE (170Hase) DEFICIENCY IN A MALE PSEUDOHERMAPHRODITE BY IN VITRO STUDIES OF TESTICULAR STEROID BIOSYNTHESIS

1981 ◽  
Vol 15 ◽  
pp. 515-515 ◽  
Author(s):  
A Vargas ◽  
E O Reiter ◽  
K Kula ◽  
L J Rodriguez-Rigau ◽  
E Steinberger ◽  
...  
Keyword(s):  
Direct Determination ◽  
In Vitro Studies ◽  
Steroid Biosynthesis

scholarly journals Gold Determination Problem in Barium Production Waste

2020 ◽  
Author(s):  
R.E. Khabibulina ◽  
K.D. Naumov, V.G. ◽  
V.G. Lobanov ◽  
V.A. Valnev
Keyword(s):  
Atomic Absorption ◽  
Raw Materials ◽  
Direct Determination ◽  
Leach Solution ◽  
Gold Content ◽  
Reliable Determination ◽  
Aqua Regia ◽  
Fire Assay ◽  
Gold Determination

The most common method for gold content determination in raw materials is fire assay. An alternative to this method is atomic absorption in a solution obtained by dissolving an initial sample in aqua regia. This study focuses on the sludge of one of the chemical plants, in which the barite concentrate (barium in sulphate form) is fused with calcium chloride at coal presence, and then leached in water. Decomposition of samples in aqua regia followed by atomic absorption analysis, as well as fire assay, showed gold content in the sludge at the level of 1-4 gram per ton. The presence of infusible and chemically resistant compounds in the sludge does not allow to the reliable determination of the gold content. Sintering with sodium peroxide for decomposition of stable compounds at 700 ∘ C, dissolution of sinter in acidic solution, evaporation and fire assay of residue made it possible to establish a reliable concentration of gold in the sludge - 10-20 gram per ton. It was found that a direct determination of gold in acidic sinter leach solution provides inadequate values associated with the influence of the background. Keywords: Gold determination, barium sludge, fire assay, atomic absorption

scholarly journals Direct Determination of Glutathione S-transferase and Glucose-6-phosphate Dehydrogenase Activities in Cells Cultured in Microtitre Plates as Biomarkers for Oxidative Stress

1998 ◽  
Vol 26 (3) ◽  
pp. 321-330 ◽  
Author(s):  
Concepción García-Alfonso ◽  
Guillermo Repetto ◽  
Pilar Sanz ◽  
Manuel Repetto ◽  
Juan López-Barea
Keyword(s):  
Oxidative Stress ◽  
Direct Determination ◽  
Cell Number ◽  
Glutathione S Transferase ◽  
Enzymatic Assays ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Gst Activity ◽  
In Cells

The enzymes glutathione S-transferase (GST) and glucose-6-phosphate dehydrogenase (G-6PDH) are implicated in the defence against oxidative stress. GST is mainly involved in the conjugation of electrophilic compounds with glutathione (GSH), although some of its isoenzymes display peroxidase activity. G-6PDH and glutathione reductase regenerate NADPH and GSH, respectively, to restore the reduced intracellular redox status following oxidative stress. Enzymatic assays for GST and G-6PDH were adapted and optimised to permit the direct in vitro determination of the effects of toxicants which induce oxidative stress in cells on microtitre plates, thereby avoiding the need to prepare cell-free extracts. To optimise the conditions of the enzymatic assays, GST activity’ was measured at substrate concentrations of 1–3mM GSH and 1–3mM 1-chloro-2,4-dinitrobenzene, while G-6PDH activity was measured at 7.5–37.5mM glucose-6-phosphate and 55–275mM NADP. Both enzymatic activities were directly proportional to cell number up to a density of 1 x 105 cells/well. The effects on GST and G-6PDH activities of three toxicants which induce oxidative stress — paraquat, iron (II) chloride and iron (III) chloride — were compared in cultured Vero cells to validate the new assays. Specific GST activity increased to 145% and 171% compared to the controls in cells treated with 5mM paraquat and 5mM iron (II) chloride, respectively, but was inhibited after exposure to 25mM iron (III) chloride. Specific G-6PDH activity increased to 136% compared to the control after exposure to 5mM paraquat, but was inhibited in cells exposed to 5mM iron (II) chloride and 25mM iron (III) chloride.

scholarly journals DERMATOLOGIC GELS SPREADABILITY MEASURING METHODS COMPARATIVE STUDY

2022 ◽  
pp. 164-168
Author(s):  
BAKHRUSHINA ELENA O. ◽  
ANUROVA MARIA N. ◽  
ZAVALNIY MICHAEL S. ◽  
DEMINA NATALIA B. ◽  
BARDAKOV ALEXANDER I. ◽  
...  
Keyword(s):  
Parallel Plate ◽  
Measured Parameter ◽  
Flow Mode ◽  
Reliable Determination ◽  
Shear Rates ◽  
Evaluation Strategies ◽  
Complex Evaluation ◽  
Different Characteristics

Objective: The main objective of our study is the comprehensive analysis and characterization of the existing spreadability evaluation strategies, the comparison of the obtained results reproducibility and convergence through the example of the 9 most widely used dermatological gels. Methods: Dolobene®, Flucinar®, Ketorol®, Contractubex®, Dr. Theiss Venen gel®, Solcoseryl®, Deep Relief®, Hepatrombin® pharmacopoeia gel samples were analyzed using parallel-plate, “slip and drag”, and viscometry methods. Analysis was performed in flow mode at 32±0.2 °C, over shear rates ranging from 0 to 350 s−1, increasing over a period of 120 s, and was maintained at the superior limit for 10 s and then decreased during the same period. At least 5 replicates of each sample were evaluated, and the upward flow curves were fitted using the Casson mathematical model. Results: Solcoseryl® and Dolobene® showed the best spreadability in the parallel-plate method (3115.66±50.00 and 3316.63±50.00, respectively); Contractubex® and Dolobene showed the best spreadability in the “slip and drag” test (73.46±0.5 and 18.32±0.5, respectively); Solcoseryl® and Contractubex® showed the best spreadability in the viscometry test (43.86±0.5 and 76.92±0.5, respectively). Conclusion: This study analyzed the existing methods for determining the spreadability using commercially available samples of the dermatological gels as examples. The viscometric and the "Slip and drag" methods use different characteristics of spreadability, giving a complex evaluation of the measured parameter in vitro. Therefore, the combination of these two methods has the greatest prospects for reliable determination of this indicator.

scholarly journals SIMPLE LIQUID CHROMATOGRAPHY METHOD WITH UV DETECTION FOR DETERMINATION OF BROMAZEPAM IN SOLID PHARMACEUTICAL DOSAGE FORMS

2019 ◽  
Vol 31 (4) ◽  
pp. 1045-1050
Author(s):  
Irena Brcina ◽  
Marija Darkovska Serafimovska ◽  
Tijana Serafimovska ◽  
Trajan Balkanov ◽  
Biljana Gjorgjeska
Keyword(s):  
Retention Time ◽  
Direct Determination ◽  
Dosage Forms ◽  
Hplc Method ◽  
Uv Detection ◽  
In Vitro Dissolution ◽  
Dissolution Test ◽  
Pharmaceutical Dosage Forms

Bromazepam is a psychoactive drug belonging to class of benzodiazepines with well-known hypnotic and sedative effects. It acts on the central neural system as an inhibitor of the neurotransmitter gamma aminobutyric acid. It is frequently prescribed for treatment of severe anxiety, to reduce tension, agitation and depression. Dissolution testing (the process by which a solid solute enters in to a solution) is a requirement for all solid oral dosage forms and is used in all phases of research and development for product release and stability testing. Tablet dissolution test is a standardized method for measuring the rate of drug release from a dosage form and it simulates the percentage of active substance that can be absorbed into the blood circulation. The direct determination of Bromazepam in pharmaceutical dosage forms using HPLC with UV detector to carry out dissolution test, have not yet been described. Development of HPLC method with UV detection for direct determination of in-vitro dissolution test of Bromazepam tablets, which can be used in the same time as method for determination of assay of Bromazepam in Bromazepam tablets, can make analytical procedure easier and quicker. A simple, selective, linear, precise and accurate RP-HPLC method has been developed and validated for assay and in-vitro dissolution test of Bromazepam tablets. The method was validated according to the guidelines set by the International Conference of Harmonization for validation of analytical procedures. The chromatographic separation was carried out using reversed phase HPLC LiChrospher RP Select B column (125 x 4.0 mm i.d.; 5μm) at temperature of 50oC. Mobile phase was consisting of the mixture of methanol, acetonitrile and potassium dihydrogen phosphate buffer (pH 7.0, adjusted with 0.5M Potassium hydroxide), with the ratio of 45:5:50 (v/v/v) and flow rate of 1.0 ml/min. The detection was carried out at 239 nm. System suitability tests were performed through evaluation of different parameters (retention time, tailing factor, retention factor and selectivity) on freshly prepared standard solution of bromazepam. The retention time of bromazepam in 0,1M HCl was 3.5 min. High percentage of recovery shows that the method is free from the interferences from excipients in test samples. Linearity of response was calculated as a ratio of peak areas of bromazepam vs. concentration in 0,1M HCl and spiked tablets in the concentration range of 0.0018 – 0.016 mgmL-1. The response was linear over the concentration range of 0.0018 – 0.016 mgmL-1 and coefficient of correlation was greater than 0.99. Good linearity shows that the proposed method may be useful for quickly and routinely determination of the percentage of dissolved bromazepam from bromazepam tablets and it can be a method of choice for assay determination in the same time.

scholarly journals Water as a Blood Model for Determination of CO2 Removal Performance of Membrane Oxygenators

Membranes ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 356
Author(s):  
Benjamin Lukitsch ◽  
Raffael Koller ◽  
Paul Ecker ◽  
Martin Elenkov ◽  
Christoph Janeczek ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Removal Rate ◽  
In Vitro Tests ◽  
Co2 Removal ◽  
Reliable Determination ◽  
Fluid Properties ◽  
Membrane Oxygenators

CO2 removal via membrane oxygenators has become an important and reliable clinical technique. Nevertheless, oxygenators must be further optimized to increase CO2 removal performance and to reduce severe side effects. Here, in vitro tests with water can significantly reduce costs and effort during development. However, they must be able to reasonably represent the CO2 removal performance observed with blood. In this study, the deviation between the CO2 removal rate determined in vivo with porcine blood from that determined in vitro with water is quantified. The magnitude of this deviation (approx. 10%) is consistent with results reported in the literature. To better understand the remaining difference in CO2 removal rate and in order to assess the application limits of in vitro water tests, CFD simulations were conducted. They allow to quantify and investigate the influences of the differing fluid properties of blood and water on the CO2 removal rate. The CFD results indicate that the main CO2 transport resistance, the diffusional boundary layer, behaves generally differently in blood and water. Hence, studies of the CO2 boundary layer should be preferably conducted with blood. In contrast, water tests can be considered suitable for reliable determination of the total CO2 removal performance of oxygenators.

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