85 results on '"Dohnal J"'
Search Results
2. Using of HPLC coupled with coulometric detector for the determination of biotin in pharmaceuticals
- Author
-
Zerzaňová, A., Žižkovský, V., Kučera, R., Klimeš, J., Jesenský, I., Dohnal, J., and Barrón, D.
- Published
- 2007
- Full Text
- View/download PDF
3. Use of the zirconia-based stationary phase for separation of ibuprofen and its impurities
- Author
-
Kučera, R., Sochor, J., Klimeš, J., and Dohnal, J.
- Published
- 2005
- Full Text
- View/download PDF
4. Stability of ramipril in the solvents of different pH
- Author
-
Hanyšová, L., Václavková, M., Dohnal, J., and Klimeš, J.
- Published
- 2005
- Full Text
- View/download PDF
5. LAMELLAR BODY COUNTS ARE PREFERABLE TO TRADITIONAL PHOSPHOLIPID ANALYSIS AS A PRIMARY ASSAY FOR FETAL LUNG MATURITY.
- Author
-
Neerhof, M G, Haney, E I, Silver, R K, Dohnal, J C, Ashwood, E R, and Lee, I S
- Published
- 2000
6. Regulation of veterinary point-of-care testing in the European Union, the United States of America and Japan.
- Author
-
Potockova, H., Dohnal, J., and Thome-Kromer, B.
- Published
- 2020
- Full Text
- View/download PDF
7. Simulation of moisture diffusion in timber bridges exposed to rain
- Author
-
Petr, Hradil, Stefania, Fortino, Metelli, Giovanni, Musci, Alessandro, Jakub Dohnal, J., and Maria, Fredriksson
- Subjects
FEM ,effect of rain ,Timber bridges, moisture content, effect of rain, single-phase models, FEM ,single-phase models ,Timber bridges ,moisture content - Published
- 2017
8. Marketing Authorisation Expenses for Veterinary Medicinal Products in Northern Europe.
- Author
-
ČERNÍČKOVÁ, Z., DOHNAL, J., and ŠALOUN, J.
- Subjects
- *
VETERINARY medicine , *MEDICINAL plants , *MARKETING , *LIFE cycles (Biology) , *COST - Abstract
The marketing authorisation process is an integral part of the life cycle of a veterinary medicinal product, which the applicant wishes to market. The costs of the marketing authorisation of veterinary medicinal products are different from state to state. The differences in marketing authorisation fees are also between particular types of the marketing authorisation procedure such as the national procedure, mutual recognition procedure, decentralised procedure and centralised procedure and whether certain state is the reference member state or concerned member state particularly applicable in either a mutual recognition procedure or a decentralised procedure. The fees is also depended on the type of the marketing authorisation application, such as full, generic, hybrid, similar biological, well-established use, fixed combination or informed consent and eventually whether a reference veterinary medicinal product is marketed in the state or not specifically for generic, hybrid and similar biological applications. If it is focused on the states in northern Europe, where Finland, Sweden, Norway, Iceland, Denmark and Baltic States Estonia, Latvia and Lithuania are included, it is a very varied group of states, where each competent authority has its own approach to the determination of marketing authorisation fees. It is important to mention that the marketing authorisation fees for veterinary medicinal products mostly are not the same as the fees for human medicinal products and also even this is paid attention. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
9. Investigating the antiproliferative activity of quinoline-5,8-diones and styrylquinolinecarboxylic acids on tumor cell lines
- Author
-
Podeszwa, B., Niedbala, H., Polanski, J., Musiol, R., Tabak, D., Finster, J., Serafin, K., Milczarek, M., Wietrzyk, J., Boryczka, S., Mol, W., Jampilek, J., Dohnal, J., Kalinowski, D.S., and Richardson, D.R.
- Published
- 2007
- Full Text
- View/download PDF
10. Decreasing test time by scan chain reorganization.
- Author
-
Bartos, P., Kotasek, Z., and Dohnal, J.
- Published
- 2011
- Full Text
- View/download PDF
11. Monitoring of recent mass movement activity in anthropogenic slopes of the Krušné Hory Mountains (Czech Republic).
- Author
-
Burda, J., Žižka, L., and Dohnal, J.
- Subjects
MASS-wasting (Geology) ,ANTHROPOGENIC soils ,SLOPES (Physical geography) ,MOUNTAINS ,LANDSLIDES ,GEOMORPHOLOGY ,TONSTEINS - Abstract
Recent mass movements currently comprise one of the main morphogenetic processes in the extensive anthropogenic relief of the foreground of the Krušné Hory Mountains in the Czech Republic. These mass movements result in several types of deep-seated slope failures, depending on the type of movement and the water saturation of the landslide material. This paper presents the results of a detailed geomorphic survey and orthophotograph analysis combined with geodetic monitoring data in an area affected by open-pit coal mining. An interdisciplinary approach has enabled an in-depth review of both the dynamics and development of recent slope failures. The article describes deep-seated landslide complex in this part of the foothills of the Krugn6 Hory Mountains. At the study site, mass movements occur in thick colluvial mantle and weathered Tertiary claystones. The main factors influencing their development include rainfall culminations, groundwater flowing from the valley of Šramnick ý Brook and former slope failures. All of the slope failures that have occurred here have originated at former slope failure sites. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
12. Lamellar body counts: a consensus on protocol.
- Author
-
Neerhof, M G, Dohnal, J C, Ashwood, E R, Lee, I S, and Anceschi, M M
- Published
- 2001
- Full Text
- View/download PDF
13. Cautionary note regarding HbA1c methods predicting the clinical status of diabetic patients.
- Author
-
CARAGHER, TIMOTHY E., DOHNAL, JAMES C., LOMONT, MICHAEL E., Caragher, T E, Dohnal, J C, and Lomont, M E
- Published
- 2000
- Full Text
- View/download PDF
14. Utilization of NIR spectroscopy in candesartan cilexetil stability study.
- Author
-
Dohnal, J., Jampilek, J., Oktabec, Z., Zerzanova, A., and Kral, V.
- Published
- 2009
- Full Text
- View/download PDF
15. The real-time identification of dynamic systems by using the neural net approach.
- Author
-
Dohnal, J. and Pivonka, P.
- Published
- 2003
- Full Text
- View/download PDF
16. Pseudorenal insufficiency with isopropyl alcohol ingestion.
- Author
-
Killeen C, Meehan T, Dohnal J, and Leikin JB
- Published
- 2011
- Full Text
- View/download PDF
17. Distribution of microfilariae of Onchocerca lienalis and Onchocerca gutturosa in the Skin of cattle in Germany and their development in Simulium ornatum and Culicoides nubeculosus following artificial infestation
- Author
-
Dohnal, J., Blinn, J., Wahl, G., and Schulz-key, H.
- Published
- 1990
- Full Text
- View/download PDF
18. Human Activity Classification Using Multilayer Perceptron.
- Author
-
Majidzadeh Gorjani O, Byrtus R, Dohnal J, Bilik P, Koziorek J, and Martinek R
- Subjects
- Automation, Housing, Humans, Wrist, Human Activities, Neural Networks, Computer
- Abstract
The number of smart homes is rapidly increasing. Smart homes typically feature functions such as voice-activated functions, automation, monitoring, and tracking events. Besides comfort and convenience, the integration of smart home functionality with data processing methods can provide valuable information about the well-being of the smart home residence. This study is aimed at taking the data analysis within smart homes beyond occupancy monitoring and fall detection. This work uses a multilayer perceptron neural network to recognize multiple human activities from wrist- and ankle-worn devices. The developed models show very high recognition accuracy across all activity classes. The cross-validation results indicate accuracy levels above 98% across all models, and scoring evaluation methods only resulted in an average accuracy reduction of 10%.
- Published
- 2021
- Full Text
- View/download PDF
19. Surface Characteristics of One-Sided Charred Beech Wood.
- Author
-
Machová D, Oberle A, Zárybnická L, Dohnal J, Šeda V, Dömény J, Vacenovská V, Kloiber M, Pěnčík J, Tippner J, and Čermák P
- Abstract
The aim of this paper was to analyze selected properties of beech wood ( Fagus sylvatica L.) treated by one-sided surface charring. Specimens were one-side charred with a hot plate using several time-temperature combinations (from 200 to 400 °C). Characteristics such as colour, discoloration, surface roughness, fire resistance, total carbohydrate content at several wood layers and decay resistance were evaluated. Surface charring was applied to the radial and tangential surfaces. Colour measurements showed that the surface of the wood turned grey due to charring. In addition to colour measurements, other experiments showed significant differences between radial and tangential specimens due to their different structures. The higher the temperature used in treating them, the lower the roughness values for radial specimens, while the trend for tangential specimens was the opposite. A smoother surface is more fire resistant, so radial specimens are generally better in this regard. Tangential specimens are more susceptible during preparation to forming cracks that impair flame resistance because a continuous protective densified layer is not formed. The determination of total carbohydrates revealed significant changes at various wood depths after surface charring. These changes were more predictable in radial specimens due to the annual ring orientation, because each layer consisted of a similar earlywood/latewood ratio. Finally, when decay resistance was assessed, weight loss was found to be lower in all specimens than in the references. The results suggest that charring at a particular combination of temperature and time improved the investigated properties of the surface-modified beech.
- Published
- 2021
- Full Text
- View/download PDF
20. Regulation of veterinary point-of-care testing in the European Union, the United States of America and Japan.
- Author
-
Potockova H, Dohnal J, and Thome-Kromer B
- Abstract
Point-of-care testing (POCT) is used to detect diseases and other conditions or to monitor therapeutic procedures. In veterinary medicine, POCT not only helps during the prevention, diagnosis and treatment of animal diseases but it also has a direct impact on human health by safeguarding food supplies and preventing zoonoses. Despite its importance, the regulation of the quality, safety and effectiveness of POCT products is rarely discussed. This review reveals that the level of regulatory surveillance of veterinary POCT products in the European Union (EU), the United States of America and Japan is strikingly different, ranging from no regulation (EU) to comprehensive regulation, which is comparable to the procedures for the regulation of human in vitro medical devices (Japan). Details about the licensing procedures in these three locations, discussion of their strengths and weaknesses, and suggestions for possible future development of the regulation of these products are also provided.
- Published
- 2020
- Full Text
- View/download PDF
21. A New Era in Pathology Consultation: The MyPathologist Electronic Consultation Tool.
- Author
-
Theparee T, Shanes E, Maurer D, Palma E, Lee HK, Benirschke R, Dohnal J, Pease G, Walls T, Thomson R Jr, and Kaul K
- Abstract
Pathologists and laboratory scientists provide valuable guidance on laboratory utilization, test ordering, interpretation, and quality control provided that clinical staff can easily access the laboratory team. To encourage consultation between clinicians with laboratory scientists and pathologists, we developed an easily accessible electronic tool termed "MyPathologist," placed on the homepage of our electronic health record system. Over its 2-year pilot, utilization of this consultation tool climbed as we continued to publicize it and incorporated education into housestaff onboarding and electronic health record training. Physician satisfaction with the tool was high. Additionally, this became the primary source of consults to our residency call service. Evaluation of MyPathologist questions received during its pilot period showed that more than half the questions were of significant educational value to the residents, often focusing on results interpretation, appropriate test ordering, and quality control. MyPathologist is a novel electronic tool for pathology consultation within our electronic health record and also represents an avenue for educating residents, improving utilization of the laboratory, and improving patient care., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
- Published
- 2018
- Full Text
- View/download PDF
22. Optimization of Dissolution Compartments in a Biorelevant Dissolution Apparatus Golem v2, Supported by Multivariate Analysis.
- Author
-
Stupák I, Pavloková S, Vysloužil J, Dohnal J, and Čulen M
- Subjects
- Computer Simulation, Equipment Design, Gastrointestinal Absorption, Gastrointestinal Tract metabolism, Multivariate Analysis, Chemistry, Pharmaceutical, Models, Biological, Pharmacokinetics, Solubility
- Abstract
Biorelevant dissolution instruments represent an important tool for pharmaceutical research and development. These instruments are designed to simulate the dissolution of drug formulations in conditions most closely mimicking the gastrointestinal tract. In this work, we focused on the optimization of dissolution compartments/vessels for an updated version of the biorelevant dissolution apparatus-Golem v2. We designed eight compartments of uniform size but different inner geometry. The dissolution performance of the compartments was tested using immediate release caffeine tablets and evaluated by standard statistical methods and principal component analysis. Based on two phases of dissolution testing (using 250 and 100 mL of dissolution medium), we selected two compartment types yielding the highest measurement reproducibility. We also confirmed a statistically ssignificant effect of agitation rate and dissolution volume on the extent of drug dissolved and measurement reproducibility., Competing Interests: The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.
- Published
- 2017
- Full Text
- View/download PDF
23. ROLE OF THE INTERNATIONAL ORGANIZATIONS IN PREVENTING THE COUNTERFEIT MEDICINES ENTRY INTO THE WORLD MARKETS.
- Author
-
Stukina V, Dohnal J, and Saloun J
- Subjects
- Crime prevention & control, Counterfeit Drugs, International Cooperation, World Health Organization
- Abstract
30 years have passed since Conference of Experts on the Rational Use of Drugs was held in Nairobi, Kenya, from 25 to 29 November 1985, where the problem of counterfeit medicines was mentioned as the international for the first time. The problem of counterfeit medicines is not only a major threat to public health and national and private economy, but also it is of great interest for key decision-making actors at the international level. The authors analyzed what has been done since that time by international organizations. Combating the counterfeiting of medicines cannot be successfully achieved by the health sector alone - World Health Organization (WHO), - so the efforts of the other United Nations (UN) organizations relevant to counterfeiting were in need and were studied in the article: World Intellectual Property Organization (WIPO), World Trade Organization (WTO), World Customs Organization (WCO), United Nations Office on Drugs and Crime (UNODC), etc. Today WHO is unable to coordinate all their activities, so the few existing proposals for establishing a new mechanism of international cooperation have been examined. Will the MEDICRIME Convention that will enter into force on January 1, 2016 be the start of the new era in the combating with the counterfeit medicines? - the authors offered their vision on the international developments.
- Published
- 2016
24. Dissolution and disintegration kinetics of high-active pharmaceutical granules produced at laboratory and manufacturing scale.
- Author
-
Smrčka D, Dohnal J, and Štěpánek F
- Subjects
- Kinetics, Microscopy, Electron, Scanning, Particle Size, X-Ray Microtomography, Chemistry, Pharmaceutical, Solubility
- Abstract
The effect of process scale-up from 4 to 400-L high-shear granulator on the release kinetics of the active ingredient from pharmaceutical granules has been investigated. The dissolution and disintegration rates of the granules were measured simultaneously by the combination of UV/vis spectroscopy and static light scattering. The granule batches were found to consist of sub-populations with qualitatively different dissolution behavior: "weaker" granules that disintegrated during dissolution, and "stronger" granules that retained their size and from which the active ingredient was gradually leached. The existence of these sub-populations was attributed to non-uniform distribution of normal and shear forces that prevail in granulators of different size. This hypothesis was confirmed by preparing granules at increasing values of the Froude number at the 4-L scale, and observing a transition from the break-up dissolution mode to the leaching dissolution mode with increasing granule densification. The simultaneous observation of solute concentration and particle size distribution during granules dissolution proved to be a useful tool for the understanding of dissolution mechanisms and for identifying non-uniformities of process conditions that can occur during scale-up., (Copyright © 2016 Elsevier B.V. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
25. Development of In Vitro-In Vivo Correlation/Relationship Modeling Approaches for Immediate Release Formulations Using Compartmental Dynamic Dissolution Data from "Golem": A Novel Apparatus.
- Author
-
Čulen M, Tuszyński PK, Polak S, Jachowicz R, Mendyk A, and Dohnal J
- Subjects
- Atorvastatin chemistry, Chemistry, Pharmaceutical, Equipment and Supplies, Gastrointestinal Tract physiology, Humans, Intestine, Small drug effects, Atorvastatin therapeutic use, Drug Liberation, Gastrointestinal Tract drug effects
- Abstract
Different batches of atorvastatin, represented by two immediate release formulation designs, were studied using a novel dynamic dissolution apparatus, simulating stomach and small intestine. A universal dissolution method was employed which simulated the physiology of human gastrointestinal tract, including the precise chyme transit behavior and biorelevant conditions. The multicompartmental dissolution data allowed direct observation and qualitative discrimination of the differences resulting from highly pH dependent dissolution behavior of the tested batches. Further evaluation of results was performed using IVIVC/IVIVR development. While satisfactory correlation could not be achieved using a conventional deconvolution based-model, promising results were obtained through the use of a nonconventional approach exploiting the complex compartmental dissolution data.
- Published
- 2015
- Full Text
- View/download PDF
26. Advances in dissolution instrumentation and their practical applications.
- Author
-
Culen M and Dohnal J
- Subjects
- Chemistry, Pharmaceutical instrumentation, Drug Liberation, Humans, Hydrodynamics, Chemistry, Pharmaceutical methods, Drug Design, Pharmaceutical Preparations chemistry
- Abstract
The rising demands on discriminatory and prediction abilities of dissolution methods and the increasing complexity of new drug products are the main driving forces of the progress in this field. The research moves forward as imperfections and shortcomings of classical methods are being described, and where the capabilities of the contemporary methods are insufficient, new methods are being developed. The review discusses these advances with respect to the issues that currently draw the most attention, i.e. correct simulation of hydrodynamics and stress forces, maintenance of sink conditions, study of precipitation, use of biorelevant media and the employment of more physiologically relevant methods in general.
- Published
- 2014
- Full Text
- View/download PDF
27. In vitro permeation of micronized and nanonized alaptide from semisolid formulations.
- Author
-
Opatrilova R, Cernikova A, Coufalova L, Dohnal J, and Jampilek J
- Subjects
- Animals, Permeability, Swine, Membranes, Artificial, Nanoparticles chemistry, Neuropeptides chemistry, Neuropeptides pharmacology, Peptides, Cyclic chemistry, Peptides, Cyclic pharmacology, Skin, Skin, Artificial
- Abstract
This study is focused on in vitro permeation of the original Czech compound, a skin/mucosa tissue regeneration promoter, known under the international nonproprietary name "alaptide," in micronized and nanonized forms. Alaptide showed a great potential for local applications for treatment and/or regeneration of the injured skin. The above mentioned technological modifications influence the permeation of alaptide through artificial or biological membranes, such as PAMPA or skin. The permeation of micronized and nanonized form of alaptide formulated to various semisolid pharmaceutical compositions through full-thickness pig ear skin using a Franz cell has been investigated in detail. In general, it can be concluded that the nanonized alaptide permeated through the skin less than the micronized form; different observations were made for permeation through the PAMPA system, where the micronized form showed lower permeation than the nanonized alaptide.
- Published
- 2013
- Full Text
- View/download PDF
28. New polyfluorothiopropanoyloxy derivatives of 5β-cholan-24-oic acid designed as drug absorption modifiers.
- Author
-
Mrózek L, Coufalová L, Rárová L, Plaček L, Opatřilová R, Dohnal J, Kráľová K, Paleta O, Král V, Drašar P, and Jampílek J
- Subjects
- Cell Proliferation drug effects, Cell Survival drug effects, Excipients metabolism, Excipients toxicity, Fibroblasts drug effects, Fibroblasts metabolism, Humans, Hydrocarbons, Fluorinated metabolism, Hydrocarbons, Fluorinated toxicity, Hydrophobic and Hydrophilic Interactions, Intestinal Absorption, MCF-7 Cells, Membranes, Artificial, Permeability, Propionates metabolism, Propionates toxicity, Skin Absorption, Solubility, Cholic Acids chemistry, Excipients chemical synthesis, Hydrocarbons, Fluorinated chemical synthesis, Propionates chemical synthesis
- Abstract
A series of final six propanoyloxy derivatives of 5β-cholan-24-oic acid (tridecafluoroctylsulfanyl- and tridecafluoroctylsulfinylethoxycarbonylpropanoyloxy derivatives) as potential drug absorption promoters (skin penetration enhancers, intestinal absorption promoters) was generated by multistep synthesis. Structure confirmation of all generated compounds was accomplished by (1)H NMR, (13)C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity (RM) was determined. The hydrophobicity (log P), solubility (logS), polar surface area (PSA) and molar volume (MV) of the studied compounds were also calculated. All the target compounds were tested for their in vitro transdermal penetration effect and as potential intestinal absorption enhancers. The cytotoxicity of all the evaluated compounds was evaluated against normal human skin fibroblast cells. Their anti-proliferative activity was also assessed against human cancer cell lines: T-lymphoblastic leukaemia cell line and breast adenocarcinoma cell line. One compound showed high selective cytotoxicity against human skin fibroblast cells and another compound possessed high cytotoxicity against breast adenocarcinoma cell line and skin fibroblast cells. Only one compound expressed anti-proliferative effect on leukaemia and breast adenocarcinoma cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC50>37μM), indicating they would have moderate cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity/polarity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and penetration enhancement effect are discussed in this article., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
29. Designing a dynamic dissolution method: a review of instrumental options and corresponding physiology of stomach and small intestine.
- Author
-
Culen M, Rezacova A, Jampilek J, and Dohnal J
- Subjects
- Animals, Gastrointestinal Tract physiology, Humans, Solubility, Chemistry, Pharmaceutical methods, Intestine, Small physiology, Pharmaceutical Preparations chemistry, Pharmacokinetics, Stomach physiology
- Abstract
Development of new pharmaceutical compounds and dosage forms often requires in vitro dissolution testing with the closest similarity to the human gastrointestinal (GI) tract. To create such conditions, one needs a suitable dissolution apparatus and the appropriate data on the human GI physiology. This review discusses technological approaches applicable in biorelevant dissolutions as well as the physiology of stomach and small intestine in both fasted and fed state, that is, volumes of contents, transit times for water/food and various solid oral dosage forms, pH, osmolality, surface tension, buffer capacity, and concentrations of bile salts, phospholipids, enzymes, and Ca(2+) ions. The information is aimed to provide clear suggestions on how these conditions should be set in a dynamic biorelevant dissolution test., (Copyright © 2013 Wiley Periodicals, Inc.)
- Published
- 2013
- Full Text
- View/download PDF
30. New propanoyloxy derivatives of 5β-cholan-24-oic acid as drug absorption modifiers.
- Author
-
Coufalová L, Mrózek L, Rárová L, Plaček L, Opatřilová R, Dohnal J, Král'ová K, Paleta O, Král V, Drašar P, and Jampílek J
- Subjects
- Cell Line, Tumor, Cell Membrane drug effects, Cell Membrane metabolism, Cell Proliferation drug effects, Cholic Acids toxicity, Humans, Hydrophobic and Hydrophilic Interactions, Permeability drug effects, Pharmacokinetics, Structure-Activity Relationship, Cholic Acids chemistry, Cholic Acids pharmacology, Intestinal Absorption drug effects, Pharmaceutical Preparations metabolism, Skin Absorption drug effects
- Abstract
A series of final twelve propanoyloxy derivatives of 5β-cholan-24-oic acid (O-propanoyl derivatives of cholic acid) as potential drug absorption modifiers (skin penetration enhancers, intestinal absorption promoters) was generated by multistep synthesis. Structure confirmation of all generated compounds was accomplished by 1H NMR, 13C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity (RM) was determined. The hydrophobicity (log P), solubility (log S), polar surface area (PSA) and molar volume (MV) of the studied compounds were also calculated. All the target compounds were tested for their in vitro transdermal penetration effect and as potential intestinal absorption enhancers. The cytotoxicity of all the evaluated compounds was evaluated against normal human skin fibroblast cells. Their anti-proliferative activity was also assessed against human cancer cell lines: T-lymphoblastic leukemia cell line and breast adenocarcinoma cell line. One compound showed selective cytotoxicity against human skin fibroblast cells and another compound possessed the highest cytotoxicity against all the tested cell lines. Only one compound expressed anti-proliferative effect on leukemia cancer cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC50>37 μM), indicating they would have moderate cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity/polarity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and enhancement effect are discussed in this article., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
31. Remotely controlled diffusion from magnetic liposome microgels.
- Author
-
Hanuš J, Ullrich M, Dohnal J, Singh M, and Stěpánek F
- Subjects
- Diffusion, Ferric Compounds chemistry, Fluorescent Dyes chemistry, Glucuronic Acid chemistry, Hexuronic Acids chemistry, Magnetic Fields, Nanoparticles chemistry, Particle Size, Surface Properties, Temperature, Alginates chemistry, Hydrogel, Polyethylene Glycol Dimethacrylate chemistry, Liposomes chemistry
- Abstract
The reversible, temperature-dependent change in the permeability of a phospholipid bilayer has been used for controlling the diffusion rate of encapsulated molecular payload from liposomes. Liposomes were preloaded with a fluorescent dye and immobilized in calcium alginate hydrogel microparticles that also contained iron oxide nanoparticles. The composite microparticles were produced by a drop-on-demand inkjet method. The ability of iron oxide nanoparticles to locally dissipate heat upon exposure to a radio-frequency (RF) alternating magnetic field was used to control the local temperature and therefore diffusion from the liposomes in a contactless way using an RF coil. Several different release patterns were realized, including repeated on-demand release. The internal structure of the composite alginate-liposome-magnetite microparticles was investigated, and the influence of microparticle concentration on the heating rate was determined. In order to achieve a temperature rise required for the liposome membrane melting, the concentration of alginate beads should be at least 25% of their maximum packing density for the nanoparticle concentration and specific absorption rate used.
- Published
- 2013
- Full Text
- View/download PDF
32. Encapsulation stability and temperature-dependent release kinetics from hydrogel-immobilised liposomes.
- Author
-
Ullrich M, Hanuš J, Dohnal J, and Štěpánek F
- Subjects
- 1,2-Dipalmitoylphosphatidylcholine chemistry, Cholesterol chemistry, Diffusion, Glucuronic Acid chemistry, Hexuronic Acids chemistry, Kinetics, Liposomes ultrastructure, Temperature, Alginates chemistry, Delayed-Action Preparations chemistry, Fluorescent Dyes administration & dosage, Hydrogel, Polyethylene Glycol Dimethacrylate chemistry, Liposomes chemistry
- Abstract
Composite microparticles consisting of a calcium alginate gel matrix with embedded liposomes made from cholesterol:DPPC (dipalmitoylphosphatidylcholine) mixtures were considered. Factors affecting the encapsulation stability of liposomes during the gel formation by ionic cross-linking--namely temperature and the cholesterol:DPPC ratio--were systematically investigated. The liposomes were found to be tolerant to Ca(2+) ions during cross-linking of the gel and stable in the hydrogel matrix for extended periods of time when cholesterol was present in the phospholipid bilayer and temperature was kept sufficiently below the phase transition. The temperature-controlled release rate of encapsulated fluorescent dye was quantified. It is shown that a defined quantity of encapsulated substance can be repeatedly released from the embedded liposomes "on-demand" by short temperature pulses of suitably chosen duration and amplitude. This makes the hydrogel-liposome composites potential candidates for applications such as controlled drug delivery or study of reaction-diffusion phenomena in compartmentalised systems., (Copyright © 2012 Elsevier Inc. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
33. Preparation of candesartan and atorvastatin nanoparticles by solvent evaporation.
- Author
-
Vaculikova E, Grunwaldova V, Kral V, Dohnal J, and Jampilek J
- Subjects
- Acetone chemistry, Atorvastatin, Biphenyl Compounds, Carboxymethylcellulose Sodium chemistry, Desiccation, Dextrans chemistry, Excipients chemistry, Methylene Chloride chemistry, Particle Size, Polyethylene Glycols chemistry, Polysorbates chemistry, Sodium Dodecyl Sulfate chemistry, Solubility, Surface-Active Agents chemistry, Benzimidazoles chemistry, Heptanoic Acids chemistry, Nanospheres chemistry, Pyrroles chemistry, Solvents chemistry, Tetrazoles chemistry
- Abstract
The solubility, absorption and distribution of a drug are involved in the basic aspects of oral bioavailability Solubility is an essential characteristic and influences the efficiency of the drug. Over the last ten years, the number of poorly soluble drugs has steadily increased. One of the progressive ways for increasing oral bioavaibility is the technique of nanoparticle preparation, which allows many drugs to thus reach the intended site of action. Candesartan cilexetil and atorvastatin, belonging to class II of the biopharmaceutical classification system, were chosen as model active pharmaceutical ingredients in this study. Forty samples were prepared either by antisolvent precipitation/solvent evaporation method or by the emulsion/solvent evaporation technique with various commonly used surface-active excipients as nanoparticle stabilizers. All samples were analyzed by means of dynamic light scattering. The particle size of the determined 36 nanoparticle samples was to 574 nm, whereas 32 samples contained nanoparticles of less than 200 nm. Relationships between solvents and excipients used and their amount are discussed. Based on the results the investigated solvent evaporation methods can be used as an effective and an affordable technique for the preparation of nanoparticles.
- Published
- 2012
- Full Text
- View/download PDF
34. Primary investigation of the preparation of nanoparticles by precipitation.
- Author
-
Vaculikova E, Grunwaldova V, Kral V, Dohnal J, and Jampilek J
- Subjects
- Chemical Precipitation, Drug Carriers, Excipients, Nanoparticles analysis, Particle Size, Solubility, Technology, Pharmaceutical, Cholestenones chemistry, Cholesterol chemistry, Nanoparticles chemistry, Pregnenolone chemistry
- Abstract
The absorption, distribution, biotransformation and excretion of a drug involve its transport across cell membranes. This process is essential and influenced by the characteristics of the drug, especially its molecular size and shape, solubility at the site of its absorption, relative lipid solubility, etc. One of the progressive ways for increasing bioavaibility is a nanoparticle preparation technique. Cholesterol, cholestenolone and pregnenolone acetate as model active pharmaceutical ingredients and some of the commonly used excipients as nanoparticle stabilizers were used in the investigated precipitation method that was modified and simplified and can be used as an effective and an affordable technique for the preparation of nanoparticles. All 120 prepared samples were analyzed by means of dynamic light scattering (Nanophox). The range of the particle size of the determined 100 nanoparticle samples was from 1 nm to 773 nm, whereas 82 samples contained nanoparticles of less than 200 nm. Relationships between solvents and used excipients and their amount are discussed.
- Published
- 2012
- Full Text
- View/download PDF
35. Investigation of new acyloxy derivatives of cholic acid and their esters as drug absorption modifiers.
- Author
-
Mrózek L, Dvořáková L, Mandelová Z, Rárová L, Řezáčová A, Plaček L, Opatřilová R, Dohnal J, Paleta O, Král V, Drašar P, and Jampílek J
- Subjects
- Animals, Cell Line, Cell Line, Tumor, Cholic Acid adverse effects, Chromatography, High Pressure Liquid, Esters adverse effects, Excipients adverse effects, Humans, Hydrophobic and Hydrophilic Interactions, Magnetic Resonance Spectroscopy, Skin drug effects, Skin metabolism, Skin Absorption drug effects, Structure-Activity Relationship, Swine, Theophylline chemistry, Theophylline pharmacokinetics, Cholic Acid chemistry, Esters chemistry, Excipients chemistry
- Abstract
Skin penetration enhancers are used in the formulation of transdermal delivery systems for drugs that are otherwise not sufficiently skin-permeable. Intestinal absorption promoters/enhancers are used as excipients in oral formulations of poorly oral-bioavailable drugs. Series of fourteen acyloxy derivatives of 5β-cholic acid as potential drug absorption modifiers was generated by multistep synthesis. The synthesis of all newly prepared compounds is presented here. Structure confirmation of all generated compounds was accomplished by (1)H NMR, (13)C NMR, IR and MS spectroscopy methods. All the prepared compounds were analyzed using RP-TLC, and their lipophilicity (R(M)) was determined. The hydrophobicity (logP) and solubility (logS) of the studied compounds were also calculated using two commercially available programs. All the target compounds were tested for their in vitro transdermal penetration activity and as potential intestinal absorption enhancers. The anti-proliferative activity of all the final compounds was also assessed against the human cancer cell lines: T-lymphoblastic leukemia cell line and the breast adenocarcinoma cell line. Their cytotoxicity was also evaluated against the normal human skin fibroblast cells. Two compounds showed anti-proliferative effect on cancer cells without affecting the growth of normal cells, which should be promising in potential development of new drugs. Most of the target compounds showed minimal anti-proliferative activity (IC(50)>37 μM), indicating they would have low cytotoxicity when administered as chemical absorption modifiers. The relationships between the lipophilicity and the chemical structure of the studied compounds as well as the relationships between their chemical structure and enhancement effects are discussed in this article., (Copyright © 2011 Elsevier Inc. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
36. Crystallization products of risedronate with carbohydrates and their substituted derivatives.
- Author
-
Kos J, Pentakova M, Oktabec Z, Krejcik L, Mandelova Z, Harokova P, Hruskova J, Pekarek T, Dammer O, Tkadlecova M, Havlicek J, Vinsova J, Kral V, Dohnal J, and Jampílek J
- Subjects
- Calorimetry, Differential Scanning, Crystallization, Etidronic Acid chemistry, Galactosides chemistry, Magnetic Resonance Spectroscopy, Molecular Structure, Risedronic Acid, Spectroscopy, Fourier Transform Infrared, Spectrum Analysis, Raman, X-Ray Diffraction, Carbohydrates chemistry, Etidronic Acid analogs & derivatives
- Abstract
The gastrointestinal absorption of bisphosphonates is in general only about 1%. To address this problem mixtures of risedronate monosodium salt with twelve varied sugar alcohols, furanoses, pyranoses and eight gluco-, manno- and galactopyranoside derivatives as counterions were designed in an effort to prepare co-crystals/new entities with improved intestinal absorption. Crystalline forms were generated by means of kinetically and/or thermodynamically controlled crystallization processes. One hundred and fifty-two prepared samples were screened by means of FT-NIR and FT-Raman spectroscopy. No co-crystal was prepared, but noteworthy results were obtained. A new solid phase of risedronate monosodium salt generated in the presence of phenyl-β-d-galactopyranoside under thermodynamically controlled crystallization conditions was found and also characterized using solid state NMR spectroscopy, X-ray powder diffraction and differential scanning calorimetry. This new polymorph was named as form P. Interactions between risedronate monosodium salt and both carbohydrates were confirmed by means of molecular dynamics simulation. In the present study the relationships between the chemical structures of the studied compounds required for crystalline form change are discussed.
- Published
- 2011
- Full Text
- View/download PDF
37. Preparation and properties of new co-crystals of ibandronate with gluco- or galactopyranoside derivatives.
- Author
-
Oktabec Z, Kos J, Mandelova Z, Havelkova L, Pekarek T, Rezacova A, Placek L, Tkadlecova M, Havlicek J, Dohnal J, and Jampílek J
- Subjects
- Crystallization, Ibandronic Acid, Spectroscopy, Fourier Transform Infrared methods, Spectrum Analysis, Raman methods, Diphosphonates chemistry, Galactosides chemistry, Glucose analogs & derivatives, Glucose chemistry
- Abstract
Mixtures of ibandronate monosodium salt with eleven gluco- and/or galacto-pyranoside derivatives as counterions were designed to prepare co-crystals with improved intestinal absorption. In general, gastrointestinal absorption of bisphosphonates after oral administration is approximately 1%. Co-crystals were generated by means of thermodynamically and/or kinetically controlled crystallization processes. Seventy-seven prepared samples were analyzed by means of FT-NIR, FT-Raman spectrometry and solid state NMR spectroscopy. New entities of ibandronate monosodium salt with phenyl-β-D-galactopyranoside were found and characterized. The absorption of these potential new co-crystals was investigated by means of PAMPA experiments. In the present study the relationships between the chemical structures of the studied compounds required for co-crystal generation are discussed.
- Published
- 2010
- Full Text
- View/download PDF
38. Product of alaptide synthesis: determination of the absolute configuration.
- Author
-
Julínek O, Setnicka V, Rezácová A, Dohnal J, Vosátka V, and Urbanová M
- Subjects
- Circular Dichroism, Humans, Optical Rotation, Protein Conformation, Neuropeptides chemistry, Peptides, Cyclic chemistry
- Abstract
Alaptide is the active substance of the veterinary dermatological ointment ALAPTID and a potential drug in human medicine. Electronic circular dichroism spectroscopy (ECD), transparent spectral region optical rotation (OR), and ab initio calculations were employed to determine the absolute configuration of alaptide. No X-ray structural data determining the absolute configuration were available. It was not possible to employ vibrational circular dichroism spectroscopy (VCD), because alaptide was not sufficiently soluble in common solvents used in VCD spectroscopy to generate reliable spectra. Both ECD spectra and OR values of alaptide solution were in good agreement with predicted data and determined unambiguously the absolute configuration of alaptide synthesized from (S)-alanine as being (S)., (Copyright (c) 2010 Elsevier B.V. All rights reserved.)
- Published
- 2010
- Full Text
- View/download PDF
39. Synthesis, antimycobacterial, antifungal and photosynthesis-inhibiting activity of chlorinated N-phenylpyrazine-2-carboxamides.
- Author
-
Dolezal M, Zitko J, Osicka Z, Kunes J, Vejsova M, Buchta V, Dohnal J, Jampilek J, and Kralova K
- Subjects
- Hydrocarbons, Chlorinated chemical synthesis, Hydrocarbons, Chlorinated chemistry, Hydrocarbons, Chlorinated pharmacology, Molecular Structure, Structure-Activity Relationship, Anti-Bacterial Agents chemical synthesis, Anti-Bacterial Agents chemistry, Anti-Bacterial Agents pharmacology, Antifungal Agents chemical synthesis, Antifungal Agents chemistry, Antifungal Agents pharmacology, Chloroplasts metabolism, Mycobacterium tuberculosis growth & development, Photosynthesis drug effects, Pyrazinamide analogs & derivatives, Pyrazinamide chemical synthesis, Pyrazinamide chemistry, Pyrazinamide pharmacology, Spinacia oleracea metabolism, Trichophyton growth & development
- Abstract
A series of sixteen pyrazinamide analogues with the -CONH- linker connecting the pyrazine and benzene rings was synthesized by the condensation of chlorides of substituted pyrazinecarboxylic acids with ring-substituted (chlorine) anilines. The prepared compounds were characterized and evaluated for their antimycobacterial and antifungal activity, and for their ability to inhibit photosynthetic electron transport (PET). 6-Chloro-N-(4-chlorophenyl)pyrazine-2-carboxamide manifested the highest activity against Mycobacterium tuberculosis strain H37Rv (65% inhibition at 6.25 μg/mL). The highest antifungal effect against Trichophyton mentagrophytes, the most susceptible fungal strain tested, was found for 6-chloro-5-tert-butyl-N-(3,4-dichlorophenyl)pyrazine-2-carboxamide (MIC=62.5 μmol/L). 6-chloro-5-tert-butyl-N-(4-chlorophenyl)pyrazine-2-carboxamide showed the highest PET inhibition in spinach chloroplasts (Spinacia oleracea L.) chloroplasts (IC50=43.0 μmol/L). For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds as well as their structure-activity relationships are discussed.
- Published
- 2010
- Full Text
- View/download PDF
40. Investigating biological activity spectrum for novel styrylquinazoline analogues.
- Author
-
Jampilek J, Musiol R, Finster J, Pesko M, Carroll J, Kralova K, Vejsova M, O'Mahony J, Coffey A, Dohnal J, and Polanski J
- Subjects
- Antitubercular Agents chemical synthesis, Antitubercular Agents pharmacology, Chloroplasts drug effects, Electron Transport drug effects, Humans, Mycobacterium Infections, Nontuberculous drug therapy, Photosynthesis drug effects, Pneumonia, Bacterial drug therapy, Pneumonia, Bacterial microbiology, Quinazolines chemical synthesis, Spinacia oleracea drug effects, Styrenes chemical synthesis, Antitubercular Agents chemistry, Nontuberculous Mycobacteria drug effects, Quinazolines chemistry, Quinazolines pharmacology, Styrenes pharmacology
- Abstract
In this study, series of ring-substituted 2-styrylquinazolin-4(3H)-one and 4-chloro-2-styrylquinazoline derivatives were prepared. The syntheses of the discussed compounds are presented. The compounds were analyzed by RP-HPLC to determine lipophilicity. They were tested for their inhibitory activity on photosynthetic electron transport (PET) in spinach (Spinacia oleracea L.) chloroplasts. Primary in vitro screening of the synthesized compounds was also performed against four mycobacterial strains and against eight fungal strains. Several compounds showed biological activity comparable with or higher than that of the standard isoniazid. It was found that the electronic properties of the R substituent, and not the total lipophilicity of the compound, were decisive for the photosynthesis-inhibiting activity of tested compounds.
- Published
- 2009
- Full Text
- View/download PDF
41. Rhodanineacetic acid derivatives as potential drugs: preparation, hydrophobic properties and antifungal activity of (5-arylalkylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl)acetic acids.
- Author
-
Dolezel J, Hirsova P, Opletalova V, Dohnal J, Marcela V, Kunes J, and Jampilek J
- Subjects
- Acetates chemical synthesis, Acetates pharmacology, Antifungal Agents chemical synthesis, Antifungal Agents pharmacology, Candida glabrata drug effects, Candida tropicalis drug effects, Rhodanine chemical synthesis, Rhodanine chemistry, Rhodanine pharmacology, Thiazolidines chemical synthesis, Thiazolidines pharmacology, Trichosporon drug effects, Acetates chemistry, Antifungal Agents chemistry, Rhodanine analogs & derivatives, Thiazolidines chemistry
- Abstract
Some [(5Z)-(5-arylalkylidene-4-oxo-2-thioxo-1,3-thiazolidin-3-yl)]acetic acids were prepared as potential antifungal compounds. The general synthetic approach to all synthesized compounds is presented. Lipophilicity of all the discussed rhodanine-3-acetic acid derivatives was analyzed using a reversed phase high performance liquid chromatography (RP-HPLC) method. The procedure was performed under isocratic conditions with methanol as an organic modifier in the mobile phase using an end-capped non-polar C(18) stationary RP column. The RP-HPLC retention parameter log k (the logarithm of the capacity factor k) is compared with log P values calculated in silico. All compounds were evaluated for antifungal effects against selected fungal species. Most compounds exhibited no interesting activity, and only {(5Z)-[4-oxo-5-(pyridin-2- ylmethylidene)-2-thioxo-1,3-thiazolidin-3-yl]}acetic acid strongly inhibited the growth of Candida tropicalis 156, Candida krusei E 28, Candida glabrata 20/I and Trichosporon asahii 1188.
- Published
- 2009
- Full Text
- View/download PDF
42. Ring-substituted 4-hydroxy-1H-quinolin-2-ones: preparation and biological activity.
- Author
-
Jampilek J, Musiol R, Pesko M, Kralova K, Vejsova M, Carroll J, Coffey A, Finster J, Tabak D, Niedbala H, Kozik V, Polanski J, Csollei J, and Dohnal J
- Subjects
- Antifungal Agents chemistry, Chloroplasts drug effects, Fungi drug effects, Hydrophobic and Hydrophilic Interactions, Hydroxyquinolines pharmacology, Photosynthesis drug effects, Quinolones pharmacology, Structure-Activity Relationship, Hydroxyquinolines chemical synthesis, Quinolones chemical synthesis
- Abstract
In the study, a series of twelve ring-substituted 4-hydroxy-1H-quinolin-2-one derivatives were prepared. The procedures for synthesis of the compounds are presented. The compounds were analyzed using RP-HPLC to determine lipophilicity and tested for their photosynthesis-inhibiting activity using spinach (Spinacia oleracea L.) chloroplasts. All the synthesized compounds were also evaluated for antifungal activity using in vitro screening with eight fungal strains. For all the compounds, the relationships between the lipophilicity and the chemical structure of the studied compounds are discussed, as well as their structure-activity relationships (SAR).
- Published
- 2009
- Full Text
- View/download PDF
43. Titania-based stationary phase in separation of ondansetron and its related compounds.
- Author
-
Zizkovský V, Kucera R, Klimes J, and Dohnal J
- Subjects
- Molecular Structure, Ondansetron chemistry, Zirconium chemistry, Chromatography, High Pressure Liquid methods, Ondansetron isolation & purification, Titanium chemistry
- Abstract
Improvements in stationary phase stability have been and remain a great task for research of new stationary phases. Metal oxide-based stationary phases appear as one of perspective alternatives to classical silica based stationary phases regarding to their similar effectiveness, different selectivity, different retention mechanism and mainly better chemical and thermal stability. In this study, the retention behaviour of ondansetron and its five pharmacopoeial impurities on TiO(2)-based reversed phase was investigated. The influence of buffer type, pH and concentration on retention was studied. Different types and amount of organic solvent in mobile phase were tested. The effect of temperature and flow rate on separation was investigated. The separation conditions were optimized and developed method validated. The retention parameters - retention time (t(R)), retention factor (k'), theoretical plate number (N), resolution between peaks due to nearby peaks (R(s)) and symmetry factor (A(s)) have been compared to parameters achieved on polybutadiene-coated zirconia column. The thermodynamic parameters of retention of analysed compounds - enthalpy, entropy and Gibbs free energy - were calculated and compared to those achieved on polybutadiene-coated zirconia column. This work proves similarity of retention behaviour of ondansetron and its five related compounds on zirconia-based and titania-based stationary phases and potential utilisation of polyethylene covered TiO(2)-based reversed stationary phase as an alternative to polybutadiene-coated ZrO(2) stationary phase in pharmaceutical analysis of ondansetron.
- Published
- 2008
- Full Text
- View/download PDF
44. RP-HPLC determination of the lipophilicity of bispyridinium reactivators of acetylcholinesterase bearing a but-2-ene connecting linker.
- Author
-
Musilek K, Jampilek J, Dohnal J, Jun D, Gunn-Moore F, Dolezal M, and Kuca K
- Subjects
- Chromatography, High Pressure Liquid methods, Drug Contamination, Molecular Structure, Stereoisomerism, Vinyl Compounds, Cholinesterase Reactivators analysis, Cross-Linking Reagents chemistry, Lipids chemistry, Pyridinium Compounds chemistry
- Abstract
New acetylcholinesterase reactivators with either a (E) or (Z)-but-2-ene connecting linker were recently prepared. The purity of the compounds was checked by HPLC and was found to be sufficient for in-vitro screening. All the discussed bispyridinium reactivators were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) to measure lipophilicity. The procedure was performed under isocratic conditions with methanol as organic modifier in the mobile phase using an end-capped non-polar C(18) stationary phase RP column. Relationships between the lipophilicity (logarithm of the RP-HPLC capacity factor, log k) and chemical structures of the studied compounds are discussed. Lipophilicity was different for the (E) and (Z) compounds and varied among the compounds in each of these groups. The lipophilicity differences also indicated an apparent influence of intramolecular interactions. Lipophilicity calculations (log P/Clog P) by means of commonly used software were not successful due to the presence of quaternary nitrogen atoms in the molecules of the reactivators.
- Published
- 2008
- Full Text
- View/download PDF
45. Investigating biological activity spectrum for novel quinoline analogues 2: hydroxyquinolinecarboxamides with photosynthesis-inhibiting activity.
- Author
-
Musiol R, Tabak D, Niedbala H, Podeszwa B, Jampilek J, Kralova K, Dohnal J, Finster J, Mencel A, and Polanski J
- Subjects
- Chlorella vulgaris drug effects, Chlorella vulgaris metabolism, Chlorophyll metabolism, Chloroplasts drug effects, Hydrophobic and Hydrophilic Interactions, Hydroxyquinolines chemistry, Lipids chemistry, Molecular Structure, Photosynthesis, Spinacia oleracea drug effects, Structure-Activity Relationship, Amides chemistry, Hydroxyquinolines chemical synthesis, Hydroxyquinolines pharmacology
- Abstract
Two series of amides based on quinoline scaffold were designed and synthesized in search of photosynthesis inhibitors. The compounds were tested for their photosynthesis-inhibiting activity against Spinacia oleracea L. and Chlorella vulgaris Beij. The compounds lipophilicity was determined by the RP-HPLC method. Several compounds showed biological activity similar or even higher than that of the standard (DCMU). The structure-activity relationships are discussed.
- Published
- 2008
- Full Text
- View/download PDF
46. Utilization of zirconia stationary phase as a tool in drug control.
- Author
-
Kucera R, Zizkovský V, Sochor J, Klimes J, and Dohnal J
- Subjects
- Biotransformation, Drug Stability, Ibuprofen chemistry, Ibuprofen isolation & purification, Ibuprofen pharmacokinetics, Parabens chemistry, Parabens isolation & purification, Parabens pharmacokinetics, Pharmaceutical Preparations chemistry, Temperature, Chromatography, High Pressure Liquid methods, Pharmaceutical Preparations analysis, Zirconium
- Abstract
Zirconia-based stationary phases represent an interesting alternative to silica-based materials. Two zirconia-based stationary phases were studied as an option for use in drug analysis. The different properties of zirconia material, distinct from RP silica-columns, were employed for the development of a novel and rapid stability monitoring HPLC method. This method enables simultaneous control of possible degradation processes of active substance (ibuprofen) as well as antimicrobial excipients (methyl-and propylparaben). The separation of ibuprofen, its two main degradation products 2-(4-isobutyrylphenyl)propionic acid and 4-isobutylacetophenone, parabens, and 4-hydroxybenzoic acid as their degradation product was successfully accomplished on a Zr-CarbonC18 column using a mobile phase consisting of acetonitrile-phosphate buffer (pH 4.8)-propan-2-ol (27:56:17, v/v/v). Detection was performed at 258 nm and the analysis was completed within 17 minutes.
- Published
- 2005
- Full Text
- View/download PDF
47. HPLC study of glimepiride under hydrolytic stress conditions.
- Author
-
Kovaríková P, Klimes J, Dohnal J, and Tisovská L
- Subjects
- Drug Stability, Hydrolysis, Oxidation-Reduction, Reference Standards, Reproducibility of Results, Sensitivity and Specificity, Sulfonylurea Compounds chemistry, Chromatography, High Pressure Liquid methods, Sulfonylurea Compounds analysis
- Abstract
Glimepiride is a modern hypoglycaemic agent, which belongs to the group of sulfonylurea derivates. In this paper, simple, specific and accurate RP-HPLC method was developed in order to study decomposition of glimepiride under the hydrolytic stress conditions (acid, neutral, alkaline and oxidative). The best separation of glimepiride and its degradation products was achieved on reverse phase C18 column. The mobile phase was composed of acetonitrile-phosphate buffer (pH 3.5, 0.03 M) (48:52, v/v). Employing RP-HPLC method, five main degradation products were detected in the exposed samples. It was found that the susceptibility of glimepiride to hydrolytic decomposition increased in following manner: neutral condition < alkaline condition < acid condition < oxidative condition.
- Published
- 2004
- Full Text
- View/download PDF
48. High-sensitivity enzyme immunoassay for C-reactive protein in dried blood spots.
- Author
-
McDade TW, Burhop J, and Dohnal J
- Subjects
- Animals, Blood Specimen Collection, Humans, Immunoenzyme Techniques, Infant, Newborn, Paper, Temperature, C-Reactive Protein analysis
- Published
- 2004
- Full Text
- View/download PDF
49. Amniotic fluid lamellar body count: a rapid and reliable fetal lung maturity test.
- Author
-
Dalence CR, Bowie LJ, Dohnal JC, Farrell EE, and Neerhof MG
- Subjects
- Amniocentesis, Female, Fetal Organ Maturity, Humans, Infant, Newborn, Phosphatidylcholines analysis, Predictive Value of Tests, Pregnancy, Prospective Studies, Respiratory Distress Syndrome, Newborn prevention & control, Sensitivity and Specificity, Sphingomyelins analysis, Amniotic Fluid chemistry, Lung embryology, Pulmonary Surfactants analysis, Respiratory Distress Syndrome, Newborn epidemiology
- Abstract
Objective: To evaluate the lamellar body count as a predictor of fetal lung maturity., Methods: We conducted a prospective clinical outcome study. Amniocentesis was performed for evaluation of fetal lung maturity status within 72 hours of delivery in 130 patients. A lamellar body count was performed on each specimen, and a lecithin-sphingomyelin ratio and lung phospholipid profile were performed when possible (insufficient sample or contamination in eight cases). Each infant was evaluated for evidence of respiratory distress syndrome (RDS)., Results: A lamellar body count exceeding 30,000/microL predicted pulmonary maturity correctly in all cases (negative predictive value 1.00). All 16 cases of RDS had counts of 30,000/microL or less. If the lamellar body count was less than 10,000/microL, the positive predictive value for RDS was 67%, and the likelihood of a mature result from chromatographic phospholipid analysis was low (one of 14, 7%). Values between 10,000-30,000/microL indicated intermediate risk (four of 39, 10%) for developing RDS. Phospholipid analysis indicated fetal lung maturity in 35 of 39 (90%) cases with lamellar body counts in the intermediate risk range., Conclusions: The lamellar body count compares favorably with traditional phospholipid testing in the prediction of fetal lung maturity. Phospholipid analysis is not needed with lamellar body counts greater than 30,000/microL or less than 10,000/microL, but may be of benefit for values in the intermediate risk range. Advantages of this test include speed, objectivity, small sample volume required, and universal availability of instrumentation.
- Published
- 1995
- Full Text
- View/download PDF
50. Lamellar body number density and the prediction of respiratory distress.
- Author
-
Bowie LJ, Shammo J, Dohnal JC, Farrell E, and Vye MV
- Subjects
- Fetus metabolism, Forecasting, Humans, Infant, Newborn, Lung embryology, Lung metabolism, Particle Size, Phospholipids metabolism, Predictive Value of Tests, Amniotic Fluid, Cytological Techniques, Prenatal Diagnosis, Respiratory Distress Syndrome, Newborn diagnosis
- Abstract
The determination of amniotic fluid lamellar body number density (LBND) has recently been shown to correlate well with other established indicators of fetal lung maturity. The authors have compared the LBND with a fetal lung phospholipid profile in predicting the clinical outcome in 52 well-documented cases. If a cutoff of 30,000/microL was used to indicate fetal lung maturity, there were no false-negative results for the LBND whereas there was one for the fetal lung profile. On the other hand, this cutoff resulted in 22 false-positive results for the LBND, whereas there were only 7 false-positive results by the fetal lung profile. The number of false-positive results by the LBND can be decreased by using a separate cutoff of less than 10,000/microL to indicate high risk for development of respiratory distress, while leaving the cutoff for predicting mature lung at 30,000/microL. This resulted in only four false-positive results for the LBND; each of these were from the same patients who also had false-positive results by the fetal lung profile. Care must be taken to ensure that the particle counter used is properly calibrated and that the appropriate cutoffs for both lung maturity and immaturity are used.
- Published
- 1991
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.