Journal articles: 'Chromogène'

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Bodendiek, I., S. Lentz, M. Seeger, and H. D. Bruhn. "Chromogenes Substrat als Antidot gegen den Thrombininhibitor Melagatran?" Hämostaseologie 23, no. 02 (2003): 97–98. http://dx.doi.org/10.1055/s-0037-1619577.

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ZusammenfassungMit In-vitro-Untersuchungen wird gezeigt, dass ein chromogenes Substrat (Chromozym TH von Roche, Mannheim) die gerinnungshemmende Wirkung des neuen Thrombininhibitors Melagatran (AstraZeneca, Mölndal, Schweden) zumindest partiell antagonisieren kann. Der hier beschriebene Antidoteffekt eines chromogenen Substrats gegenüber einem Thrombininhibitor könnte seine Erklärung darin finden, dass eine Substratkompetition zwischen Thrombins im Testsystem und Fibrinogen, Thrombininhibitor und chromogenem Substrat vorliegt. Tierversuche unter Einbeziehung weiterer Thrombininhibitoren könnten klären, ob die beschriebene Antidotwirkung die beobachteten Blutungskomplikationen tatsächlich reduzieren kann oder ob ein In-vitro-Phänomen vorliegt, das in vivo wenig Relevanz besitzt.

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Kallsen, B., J. Liebsch, M. Lins, et al. "Chromogenes Substrat als Antidot gegen den Thrombininhibitor Ro 46-6240?" Hämostaseologie 15, no. 01 (1995): 54–56. http://dx.doi.org/10.1055/s-0038-1655287.

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ZusammenfassungAnhand von In-vitro-Untersuchungen wird gezeigt, daß ein chromogenes Substrat (Chromozym TH der Firma Boehringer/Mannheim) die gerinnungshemmende Wirkung des neuen Thrombininhibitors Ro 46-6240 (Firma Hoffmann-LaRoche/ Grenzach-Wyhlen) zumindest partiell antagonisieren kann. Der hier beschriebene Antidoteffekt eines chromogenen Substrats gegenüber einem Thrombininhibitor könnte seine Erklärung darin finden, daß eine Substratkompetition des Thrombins im Testsystem gegenüber Fibrinogen, Thrombininhibitor und chromogenem Substrat vorliegt. In Tierversuchen müßte weiterhin geklärt werden, ob die beschriebene Antidotwirkung tatsächlich durch den Thrombininhibitor verursachte Blutungskomplikationen vermindern kann oder ob nur ein In-vitro-Phänomen vorliegt, das in vivo wenig Relevanz hat.

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Farag, A. M., T. Ozawa, and E. F. Mammen. "Gerinnungsbestimmungen am Zentrifugalanalysator - Messungen mit chromogenen Substraten und mit der Fibringerinnung." Hämostaseologie 11, no. 01 (1991): 8–11. http://dx.doi.org/10.1055/s-0038-1660274.

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ZusammenfassungZiel aller traditionellen Gerinnungstests ist die Fibrinogenumwandlung in Fibrin durch Thrombin. Die Gerinnselbildung wird entweder mechanisch oder photooptisch gemessen. Die Entwicklung chromogener Substrate zur Bestimmung von Gerinnungsenzymen hat eine spektrophotometrische Erfassung der Enzymreaktionen ermöglicht, die zur Automatisierung der Analysen mittels Zentrifugalanalysatoren im klinisch chemischen Laboratorium geführt hat.Das von Instrumentation Laboratory (IL) entwickelte Automated Coagulation Laboratory (ACL)-System bietet Zentrifugalanalysatoren, die nicht nur Fibringerinnungstests, sondern auch chromogene Substrattests weitgehend automatisch durchführen (ACL 200, und 300 und 300 Research). Die Tests sind bei den 200und 300-Geräten vorprogrammiert, mit dem 300-Research-Gerät ist dagegen diese Vorprogrammierung zu umgehen. Somit können mit dem Gerät fast unbegrenzt neue Einphasenoder Zweiphasentests unter Verwendung von Gerinnungsverfahren oder chromogenen Substraten entwickelt werden. Das ACL-System ist einfach zu bedienen, hat eine ausgezeichnete Präzision und Reproduzierbarkeit und wirkt durch Automatisierung und niedrige Testvolumina kostendämpfend.

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Rosén, S. "Chromogenic methods in coagulation diagnostics." Hämostaseologie 25, no. 03 (2005): 259–66. http://dx.doi.org/10.1055/s-0037-1619659.

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ZusammenfassungChromogene Peptidsubstrate wurden vor mehr als 30 Jahren entwickelt. Obgleich sich die Anwendung chromogener Substratmethoden bei der Gerinnungs- und Fibrinolyse-Diagnostik nicht so rasch etablierte, wie anfangs angenommen, haben sich diese Methoden inzwischen zur Bestimmung verschiedener Analyte (z. B. Antithrombin, F.VIII, Protein C, Plasminogen, Plasmininhibitor, Heparine und Pentasaccharide) einen festen Platz erobert. Das Aufkommen direkter Thrombin- und Faktor-Xa-Inhibitoren veranlasste zur Entwicklung neuer, spezifischer chromogener Methoden. Diese können Eingang in die Routineanwendung finden, wenn sich die neuen Wirkstoffe als valider Ersatz für Kumarinderivate erweisen. Auch für andere Analyte wurde eine Vielzahl chromogener Untersuchungsmethoden entwickelt. Das aktuelle Interesse an globalen chromogenen Methoden für die Thrombinbildung und den Protein-C-Weg kann sich als klinisch relevant herausstellen und damit Eingang in die Routineanwendung finden.

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Maguire, G. A. "Elimination of the "chromogen oxidase" activity of bilirubin oxidase added to obviate bilirubin interference in hydrogen peroxide/peroxidase detecting systems." Clinical Chemistry 31, no. 12 (1985): 2007–8. http://dx.doi.org/10.1093/clinchem/31.12.2007.

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Abstract The use of bilirubin oxidase to remove interference by bilirubin in hydrogen peroxide/peroxidase detecting systems is hampered by its inherent "chromogen oxidase" activity (its ability to oxidize the chromogens used in the systems). This unwanted activity is greater than 99% inhibited by 0.5 mmol/L cyanide, 97% inhibited by 20 mmol/L azide. At these same concentrations, they inhibit bilirubin oxidase activity by 95% and 73%, respectively. Sequential addition of reagents allows the use of bilirubin oxidase without interference by the chromogen oxidase activity.

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Annapurna, M. Mathrusri, M. E. Bhanoji Rao, and B. V. V. Ravi Kumar. "Spectrophotometric Determination of Raloxifene Hydrochloride in Pharmaceutical Formulations." E-Journal of Chemistry 4, no. 1 (2007): 79–82. http://dx.doi.org/10.1155/2007/480625.

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Three new simple, sensitive, rapid and economical spectrophotometric Methods (A, B and C) have been developed for the determination of Raloxifene Hydrochloride in pharmaceutical bulk and tablet dosage form. Method A is based on the formation of yellow colored chromogen with 0.1N Sodium hydroxide exhibiting maximum absorbance against the corresponding reagent blank. The method B is based on the reaction of Raloxifene with Ferric chloride and 1, 10-phenanthroline to form blood red colored chromogen. The method C is based on the formation of blood red colored chromogen with Ferric chloride and 2, 2' bipyridyl. The absorbencies of the chromogens were measured at their respective wavelength of maximum absorbance against the corresponding reagent blank. The proposed methods have been successfully applied to the analysis of the bulk drug and its tablet dosage form. The methods have been statistically evaluated and were found to be precise and accurate.

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Sharma, Sangita, Madhurjya Neog, Vipul Prajapati, Hiren Patel, and Dipti Dabhi. "Spectrophotometric Estimation of Sulfadoxine in Pharmaceutical Preparations." E-Journal of Chemistry 7, no. 4 (2010): 1246–53. http://dx.doi.org/10.1155/2010/289723.

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Four simple, sensitive, accurate and rapid visible spectrophotometric methods (A, B, C and D) have been developed for the estimation of sulfadoxine in pharmaceutical preparations. They are based on the diazotization of sulfadoxine with sodium nitrite and hydrochloric acid followed by coupling withN-(1-naphthyl) ethylenediamine dihydrochloride (Method A) to form pink coloured chromogen, diphenylamine (Method B) to form light pink coloured chromogen, chromotropic acid (in alkaline medium) (Method C) to form orange coloured chromogen, Resorcinol (in alkaline medium) (Method D) to form light orange coloured chromogen and exhibiting absorption maxima (λmax) at 536 nm, 524 nm, 520 nm and 496 nm respectively. The coloured chromogens formed are stable for more than 2 h. Beer’s law was obeyed in the concentration range of 1.0 - 5.0 μg/mL in Method A , 5.0 - 25.0 μg/mL in Method B, 5.0 - 25.0 μg/mL in Method C and 4.0 - 8.0 μg/mL in Method D respectively. The results of the three analysis have been validated statistically and by recovery studies. The results obtained in the proposed methods are in good agreements with labeled amounts, when marketed pharmaceutical preparations are analyzed.

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8

Alban, S. "Chromogene Methode zur funktionellen TFPI-Bestimmung." Hämostaseologie 25, no. 03 (2005): 286–92. http://dx.doi.org/10.1055/s-0037-1619658.

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ZusammenfassungAufgrund der vielfältigen TF(tissue factor)-Funktionen ist auch sein natürlicher Gegenspieler, der TFPI (tissue factor pathway inhibitor) von Interesse. Zur quantitativen TFPIBestimmung kann die Antigenkonzentration oder die TFPIAktivität gemessen werden. Methode: Es wird ein chromogener Test zur funktionellen Bestimmung des TFPI vorgestellt und für die Anwendung im Routinelabor modifiziert. Anhand der Testung von über 700 Proben aus einer Heparinstudie mit Gesunden wurde seine Praxistauglichkeit geprüft. Mit der beschriebenen Methode werden sowohl die Aktivität von freiem als auch Lipoprotein-assoziiertem TFPI erfasst. Zusammenfassung: Der chromogene Test erwies sich als einfach und schnell durchführbar und zeichnet sich durch eine hohe Reproduzierbarkeit aus. Insbesondere für die Bestimmung von TFPI in Plasmaproben nach Heparingabe bietet er aufgrund der exzellenten Korrelation eine schnellere und ökonomischere Alternative zur Bestimmung der Gesamt-TFPI-Antigenkonzentration mittels ELISA.

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Silva, A. P., R. G. Silva, B. Cogliati, A. S. M. Dias, A. E. Le Bas, and F. J. Hernandez-Blazquez. "Bleaching of melanin in the epidermis of South American fur seal and its application on enzyme immunohistochemistry." Pesquisa Veterinária Brasileira 31, no. 3 (2011): 267–70. http://dx.doi.org/10.1590/s0100-736x2011000300014.

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The South American fur seal (Arctocephalus australis) is an amphibious marine mammal distributed along the Atlantic and Pacific coasts of South America. The species is well adjusted to different habitats due to the morphology of its fin-like members and due to some adaptations in their integumentary system. Immunohistochemical studies are very important to evaluate the mechanisms of skin adaptation due the differential expression of the antigens present in the tissue depending of the region of the body surface. However, its strongly pigmented (melanin) epidermis prevents the visualization of the immuno-histochemical chromogens markers. In this study a melanin bleaching method was developed aimed to allow the visualization of the chromogens without interfering in the antigen-antibody affinity for immunohistochemistry. The analysis of PCNA (proliferating cell nuclear antigen) index in the epidermis of A. australis by immunohistochemistry with diaminobenzidine (DAB) as chromogen was used to test the method. The bleaching of the melanin allowed to obtain the cell proliferation index in epidermis and to avoid false positive results without affecting the immunohistochemical results.

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Whitehead, T. P., E. A. Bevan, L. Miano, and A. Leonardi. "Defects in diagnostic kits for determination of urate in serum." Clinical Chemistry 37, no. 6 (1991): 879–81. http://dx.doi.org/10.1093/clinchem/37.6.879.

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Abstract Certain diagnostic kits that measure serum urate by the Barham and Trinder principle of enzymic liberation of oxygen and its combination with chromogens can give results for urate in fresh serum that are approximately 20% lower than results from serum stored at ambient temperature for 72 h. In fresh serum, antioxidants compete with chromogen for liberated peroxyl-oxygen. We postulate that during storage the interfering antioxidant substances are destroyed. In some diagnostic kits, L-ascorbate oxidase is added to the reaction, eliminating some but not all of this effect. We discuss defects of several commercially available kits for determination of serum urate and recommend comparing results of these kits with results from the phosphotungstic acid method as a precaution against falsely low results.

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11

Luhman, C. M., S. T. Galloway, and D. C. Beitz. "Simple enzymatic assay for determining cholesterol concentrations in bile." Clinical Chemistry 36, no. 2 (1990): 331–33. http://dx.doi.org/10.1093/clinchem/36.2.331.

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Abstract We use bilirubin oxidase (EC 1.3.3.5) to remove interference by bilirubin in the assay of cholesterol concentration in bile by standard enzymatic methods. Samples are treated for 10 min with nonlimiting amounts of bilirubin oxidase to form biliverdin from bilirubin before the reagent for cholesterol is added. The relatively small interference by biliverdin is easily eliminated by use of sample blanks. The method is simple, convenient, and not hampered by the "chromogen oxidase" activity (the inherent ability of bilirubin oxidase to oxidize some chromogens) that plagues other assays of this type. Using this assay, we have accurately and precisely determined the concentration of cholesterol in bile. Such elimination of bilirubin will also be useful in assays of other biliary constituents or constituents of urine or icteric plasma.

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Olschewski, A., G. Nowak, E. Bucha, and U. Lange. "Ecarin Chromogenic Assay." Hämostaseologie 25, no. 03 (2005): 293–300. http://dx.doi.org/10.1055/s-0037-1619663.

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ZusammenfassungDer ECA (ecarin chromogenic assay) wurde zur quantitativen Bestimmung von direkten Thrombininhibitoren entwickelt. Er ist eine Weiterentwicklung der ECT (ecarin clotting time) und basiert wie diese auf der Prothrombinaktivierung durch Ecarin, einem Schlangengiftenzym aus Echis carinatus. Durch die entstehenden Aktivierungsprodukte Meizothrombin und Meizothrombin-Des-Fragment 1 wird im ECA ein chromogenes Substrat gespalten, während im Gerinnungsassay ECT plasmatisches Fibrinogen zu Fibrin umgesetzt wird.Die Aktivität von Meizothrombin und Meizothrombin-Des-Fragment 1 wird konzentrationsabhängig durch direkte Thrombininhibitoren gehemmt. Der ECA kann als ECA-H zur quantitativen Hirudinbestimmung und als ECA-T zur Bestimmung von synthetischen Thrombinhemmstoffen eingesetzt werden. Am Beispiel von Hirudin, Argatroban und Melagatran erwies sich der ECA als äußerst präzise und sensitive Methode, die die Vorteile der ECT mit denen chromogener Tests verbindet. Im Vergleich zu aPTT und ECT weist der ECA sehr geringe interindividuelle Schwankungen auf. Er wird weder von der Prothrombin-noch von der Fibrinogenkonzentration im Plasma beeinflusst.

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Molitor, B., R. Klingel, and G. Hafner. "Überwachung der Heparintherapie bei Akutdialysen." Hämostaseologie 25, no. 03 (2005): 272–78. http://dx.doi.org/10.1055/s-0037-1619661.

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ZusammenfassungDie Antikoagulation im Rahmen einer Nierenersatztherapie ist notwendig, um die Thrombosierung der Filter zu verhindern und den Blutfluss zu erhalten. Ausnahmen bilden Patienten mit akutem Nierenversagen und Begleiterkrankungen (z. B. Sepsis, Multiorganversagen), bei denen eine drohende Blutung das extrakorporale Verfahren auch ohne Antikoagulation erfordern kann.Am häufigsten wird unfraktioniertes Heparin als Antikoagulanz eingesetzt. Mit niedermolekularen Heparinen liegen ebenfalls positive Erfahrungen vor. Zur sicheren Therapieführung ist ein Monitoring der Antikoagulation notwendig. Die aktivierte Vollblut-Gerinnungszeit (ACT), die aktivierte partielle Thromboplastinzeit (aPTT) und die Anti-Faktor-Xa-Bestimmung mit chromogenen Substraten stehen als Routine- und Point-of-Care-Tests zur Verfügung. Zum Monitoring der niedermolekularen Heparine (NMH) kann nur die Anti-Faktor-Xa-Messung eingesetzt werden. Die spezifischste und valideste Methode für das Therapiemonitoring der Heparine ist der Anti-Faktor-Xa-Test mit Hilfe chromogener Substrate. Da wenig kontrollierte Studien zur Antikoagulanzientherapie und Monitoring mit dem Anti-Faktor-Xa-Test in der akuten Nierenersatztherapie vorliegen, beruhen die Empfehlungen auf den Erfahrungen mit der chronischen Nierenersatztherapie.

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Hermiston, M. L., C. B. Latham, J. I. Gordon, and K. A. Roth. "Simultaneous localization of six antigens in single sections of transgenic mouse intestine using a combination of light and fluorescence microscopy." Journal of Histochemistry & Cytochemistry 40, no. 9 (1992): 1283–90. http://dx.doi.org/10.1177/40.9.1506665.

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To study the geographic differentiation of the intestinal epithelium and to understand the complex lineage relationships of its cell populations, it is often necessary to visualize the protein products of multiple genes in sections prepared from different positions along the duodenal-to-colonic and/or crypt-to-villus axes. Multilabel fluorescence or brightfield immunohistochemical techniques have previously been used for this purpose. However, the number of antigens that can be identified on single sections is limited in fluorescence microscopy by the number of fluorophores with non-overlapping absorption and emission characteristics, in brightfield microscopy by the number of visually distinguishable chromogens, and in both methods by the availability of primary antisera raised in multiple species. We have now used a combination of light and fluorescence microscopic techniques to increase the number of antigens that can be detected in a single section to six. Sections were sequentially stained using immunogold with silver intensification, peroxidase-antiperoxidase with diaminobenzidine chromogen, and peroxidase-anti-peroxidase with alpha-naphthol/basic dye as chromogen, followed by simultaneous fluorescent detection with fluorescein, 7-amino-4-methylcoumarin-3-acetic acid, and beta-phycoerythrin. This method enables up to four separate antigens to be visualized within a single cell and two additional antigens to be detected in unrelated cells. The technique is illustrated by examining the cellular patterns of expression of liver fatty acid binding protein/human growth hormone fusion genes in the intestinal epithelium of adult transgenic mice. It should be generally applicable to other experimental systems that require localization of multiple antigens in single tissue sections.

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Bakker, A. J. "Influence of monoclonal immunoglobulins in direct determinations of iron in serum." Clinical Chemistry 37, no. 5 (1991): 690–94. http://dx.doi.org/10.1093/clinchem/37.5.690.

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Abstract I compared seven buffers and four chromogens for determining serum iron, to evaluate the frequency of falsely high or low concentrations of iron in 59 sera containing monoclonal immunoglobulins. The results for these direct assays with untreated sera were compared with those obtained by a proposed reference method (Br J Haematol 1978;38:291-4) with protein-free filtrates of the same sera. Sera with monoclonal immunoglobulins sometimes yielded erroneous results; the frequency of errors, which could be as much as 29% (17/59), depended on the composition of buffer and color reagent. Addition of thiourea or a detergent (Triton X-405) to some of the buffers lowered the frequency of errors, but did not abolish them. In only a few of the investigated buffer/chromogen combinations were no errors found. Detection of errors by analyzing the absorbance pattern after mixing sample and buffer was not always successful. Moreover, the presence and magnitude of errors bore no relationship to the type or the concentration of the monoclonal immunoglobulins. Unfortunately, the problem cannot be solved by a simple two- or threefold dilution of the sample.

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Lakos, S., and A. I. Basbaum. "Benzidine dihydrochloride as a chromogen for single- and double-label light and electron microscopic immunocytochemical studies." Journal of Histochemistry & Cytochemistry 34, no. 8 (1986): 1047–56. http://dx.doi.org/10.1177/34.8.2426333.

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Although very sensitive chromogens have been adapted for localization of horseradish peroxidase in anterograde and retrograde tracing studies, they have not been successfully applied in immunocytochemical studies. This report describes a protocol which uses benzidine dihydrochloride (BDHC) as the chromogen for light (LM) and electron microscopic (EM) immunocytochemical studies. The protocol is comparable to that used for tetramethylbenzidine, except that the pH of the reaction is above 6.0. At the LM level, the BDHC reaction product is bluish-green and crystalline. Both the color and form of the product are readily distinguished from the reddish-brown DAB reaction product. LM double-labeling studies are therefore feasible. The use of BDHC also increases significantly the sensitivity of the immunoreaction. Higher fixative concentrations can be used, less detergent is necessary, and higher primary antibody dilutions are possible. By osmicating at 45 degrees C in an s-collidine buffer it is possible to preserve the soluble BDHC reaction product for EM analysis. Immunoreactive cells are particularly well labeled with this new protocol. The BDHC crystals are easily detected at the EM level and can be distinguished from flocculent DAB reaction product. This feature makes EM double-labeling studies possible.

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Abdelmageed, Osama H. "Development and Validation of a Spectrophotometric Method for the Determination of Macrolide Antibiotics by Using 2,4-Dinitrophenylhydrazine." Journal of AOAC INTERNATIONAL 90, no. 2 (2007): 364–71. http://dx.doi.org/10.1093/jaoac/90.2.364.

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Abstract A simple, novel, sensitive, and specific spectrophotometric method was developed and validated for the determination of azithromycin (AZ), clarithromycin (CLA), and roxithromycin (ROX) in bulk powders and their dosage forms. The proposed method was based on the interaction of any of the cited drugs with 2,4-dinitrophenylhydrazine in the presence of an acid catalyst, followed by treatment with a methanolic solution of potassium hydroxide; an intensely colored chromogen was formed that was measured in dimethylformamide, as the diluting solvent, at 542−545, 523−526, and 539−542 nm for AZ, CLA, and ROX, respectively. All variables affecting the development of the measured chromogens were studied and optimized. Beer's law was obeyed in the concentration ranges of 540, 535, and 535 μg/mL for AZ, CLA, and ROX, respectively, with good correlation coefficients (0.99910−9999). The limits of detection for this method ranged from 0.77 to 1.47 μg/mL, and the relative standard deviations were 1.24−1.8%. The proposed method was applied successfully to the determination of the 3 drugs in pure bulk form, tablets, and suspensions without interference from commonly encountered additives. The results compared favorably with those of a previously reported method. The mechanism of the reaction was also studied.

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Habashy, M. M., M. S. Antonious, M. Abdel-Kader, and M. S. A. Abdel-Mottaleb. "Free Rotor Styrylcyanine Chromogens." Laser Chemistry 6, no. 6 (1986): 381–89. http://dx.doi.org/10.1155/lc.6.381.

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Fluorescence spectra (maximum wavelength λF) and fluorescence quantum yields (φF) were measured for four structurally related styrylcyanine chromogens of the pyridinium and quinolinium type (1–4) in different solvents at ambient temperature and 77 K. The response of λF and φF values to changes in solvent polarity, solvent hydrogen bonding donor strength, viscosity and temperature was a sensitive function of chromogen structure. The sensitivities of the λF and φF values correlate with the degree of charge transfer character of the S1,CT state; Stokes shift of fluorescence was progressively decreased while φF value was enhanced as the CT character of S1,CT state increases. Moreover, a large edge-excitation red shift was observed in ethanol glass at 77 K. The dominant photophysical features for these dyes are discussed in terms of strong emission from an intramolecular CT state characterized by different solvation sites indicated by the observation of the excitation-wavelength dependent phenomenon in ethanol at 77 K and an important non-radiative decay channel involving rotation of the different parts of molecules leading to a more relaxed weakly fluorescent S1,CT created in fluid media. The viscosity dependence of fluorescence properties (a marked increase in φF was observed with increasing viscosity) suggests that these dyes can be useful reporters of microviscosity for different sites in various organized assemblies. Moreover, it was suggested that increasing H-bonding donor strength of the solvent activates a rotatory non-radiative decay channel probably by localizing charge densities and decreasing CT nature of the S1,CT state.

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Sixou, Pierre. "Matériaux chromogenes pour applications optiques." Annales de Chimie Science des Matériaux 29, no. 6 (2004): 115–30. http://dx.doi.org/10.3166/acsm.29.6.116-130.

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Mazuhier, Denis, and André Tonck. "Matériaux chromogenes pour applications optiques." Annales de Chimie Science des Matériaux 29, no. 6 (2004): 131–42. http://dx.doi.org/10.3166/acsm.29.6.131-142.

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Israel, L. F. S., R. F. Rabello, S. C. B. Domingos, and L. S. Medeiros. "Produção de biofilme por Staphylococcus chromogenes isolados de amostras de leite provenientes de rebanhos bovinos com mastite." Arquivo Brasileiro de Medicina Veterinária e Zootecnia 70, no. 6 (2018): 1943–49. http://dx.doi.org/10.1590/1678-4162-9866.

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RESUMO Foram estudadas 135 vacas mestiças, provenientes de 10 rebanhos leiteiros no estado do Acre. O objetivo foi identificar espécies de Staphylococcus isoladas dos quartos mamários de vacas com mastite e, posteriormente, avaliar a capacidade de produção de biofilme pela espécie Staphylococcus chromogenes. A caracterização dos isolados presentes nas amostras encontradas, correspondentes a Staphylococcus sp., foi realizada utilizando-se a técnica do MALDI TOF MS (Matrix Associated Laser Desorption-Ionization - Time of Flight - Mass Spectrometry). Foram identificados: S. chromogenes (36), Staphylococcus saprophyticus (5), S. chromogenes ou Staphylococcus hycus (5), Staphylococcus haemolyticus (4), Staphylococcus epidermidis (3), Staphylococcus hycus (3), Staphylococcus aureus (1), Staphylococcus auriculares (1), Staphylococcus kloosii (1) e Staphylococcus xylosus (1). A espécie S. chromogenes correspondeu a 60% dos isolados do gênero (17 isolados coagularam o plasma de coelho no teste da coagulase em tubo), sendo 83,3% dos isolados (30/36) produtores de biofilme, não estando esse fator de virulência associado ao fenótipo de coagulação do plasma. A identificação desses microrganismos é importante para a elucidação da etiologia da mastite bovina. O alto percentual de S. chromogenes, produtores de biofilme, isolados de vacas com mastite é um achado relevante e pode revelar uma mudança de perfil na colonização de agentes etiológicos causadores dessa enfermidade.

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SAITO, Keiko, Tsuyoshi HIGUCHI, Aki KURATA, Tsuguaki FUKUYASU, and Kiyomi ASHIDA. "Characterization of Non-Pigmented Staphylococcus chromogenes." Journal of Veterinary Medical Science 58, no. 7 (1996): 711–13. http://dx.doi.org/10.1292/jvms.58.711.

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23

Giacalone, Michael, Nestor B. Tomycz, and Wendall T. Caraway. "Cefoxitin: Another Porter-Silber Chromogen." Southern Medical Journal 78, no. 4 (1985): 493. http://dx.doi.org/10.1097/00007611-198504000-00040.

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Yap, Wai Ho, Zhenshui Zhang, and Yue Wang. "Distinct Types of rRNA Operons Exist in the Genome of the Actinomycete Thermomonospora chromogena and Evidence for Horizontal Transfer of an Entire rRNA Operon." Journal of Bacteriology 181, no. 17 (1999): 5201–9. http://dx.doi.org/10.1128/jb.181.17.5201-5209.1999.

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ABSTRACT We describe here the presence of two distinct types of rRNA operons in the genome of a thermophilic actinomycete Thermomonospora chromogena. The genome of T. chromogena contains six rRNA operons (rrn), of which four complete and two incomplete ones were cloned and sequenced. Comparative analysis revealed that the operon rrnB exhibits high levels of sequence variations to the other five nearly identical ones throughout the entire length of the operon. The coding sequences for the 16S and 23S rRNA genes differ by approximately 6 and 10%, respectively, between the two types of operons. Normal functionality ofrrnB is concluded on the basis of the nonrandom distribution of nucleotide substitutions, the presence of compensating nucleotide covariations, the preservation of secondary and tertiary rRNA structures, and the detection of correctly processed rRNAs in the cell. Comparative sequence analysis also revealed a close evolutionary relationship between rrnB operon of T. chromogena and rrnA operon of another thermophilic actinomycete Thermobispora bispora. We propose thatT. chromogena acquired rrnB operon fromT. bispora or a related organism via horizontal gene transfer.

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Mikheev, Yu A., L. N. Guseva, and Yu A. Ershov. "Nature of chromogens of protonated azobenzene." Russian Journal of Physical Chemistry A 89, no. 2 (2014): 224–31. http://dx.doi.org/10.1134/s003602441501015x.

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Lee, Soo In, Sun Do Kim, Ji Heon Park, and Soo-Jin Yang. "Species Distribution, Antimicrobial Resistance, and Enterotoxigenicity of Non-aureus Staphylococci in Retail Chicken Meat." Antibiotics 9, no. 11 (2020): 809. http://dx.doi.org/10.3390/antibiotics9110809.

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Non-aureus staphylococci (NAS), including coagulase-negative staphylococci, have emerged as important causes of opportunistic infections in humans and animals and a potential cause of staphylococcal food poisoning. In this study, we investigated (i) the staphylococcal species profiles of NAS in in retail chicken meat, (ii) the phenotypic and genotypic factors associated with antimicrobial resistance in the NAS isolates, and (iii) the prevalence of classical and newer staphylococcal enterotoxin (SE) genes. A total of 58 NAS of nine different species were isolated from retail raw chicken meat samples. The occurrence of multidrug resistance in the NAS, particularly S. agnetis and S. chromogenes, with high resistance rates against tetracycline or fluoroquinolones were confirmed. The tetracycline resistance was associated with the presence of tet(L) in S. chromogenes and S. hyicus or tet(K) in S. saprophyticus. The occurrence of fluoroquinolone resistance in S. agnetis and S. chromogenes was usually associated with mutations in the quinolone resistance determining regions (QRDR) of gyrA and parC. In addition, the frequent presence of SE genes, especially seh, sej, and sep, was detected in S. agnetis and S. chromogenes. Our findings suggest that NAS in raw chicken meat can have potential roles as reservoirs for antimicrobial resistance and enterotoxin genes.

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Georghiou, Paris E., and Chi Keung (Jimmy) Ho. "The chemistry of the chromotropic acid method for the analysis of formaldehyde." Canadian Journal of Chemistry 67, no. 5 (1989): 871–76. http://dx.doi.org/10.1139/v89-135.

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Formaldehyde is present in the indoor air of many industrial and non-industrial environments. The procedure for its analysis which is commonly employed in North America is a NIOSH recommended one that uses chromotropic acid and concentrated sulphuric acid. The nature of the purple chromogen that is produced in the analytical procedure has not been fully understood until now. Using 1H and 13C nuclear magnetic resonance spectroscopic techniques and calibration line studies, evidence has been obtained to support the hypothesis that the chromogen has a mono-cationic dibenzoxanthylium structure and not a para,para-quinoidal one that is commonly cited. Keywords: Formaldehyde, formaldehyde analysis, chromotropic acid, chromogen, dibenzoxanthylium cation.

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Ortin, A., M. T. Verde, J. J. Ramos, et al. "Staphylococcus chromogenes-induced folliculitis in goat kids." Veterinary Record 166, no. 9 (2010): 273–74. http://dx.doi.org/10.1136/vr.b4779.

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Prakash, K. Vanitha, and Jangala Venkateswara Rao. "Spectrophometric Determination of Nelfinavir Mesylate." E-Journal of Chemistry 3, no. 2 (2006): 78–82. http://dx.doi.org/10.1155/2006/160909.

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Two new simple, sensitive, rapid and economical Spectrophotometric Methods (A and B) have been developed for the determination of Nelfinavir Mesylate in pharmaceutical bulk and tablet dosage form. The method A is based on the reaction of Nelfinavir with ferric chloride, potassium ferricyanide and hydrochloric acid to form a bluish green colored chromogen. The Method B is based on the formation of blood red colored chromogen with Ferric chloride and 1,10-phenanthroline. The absorbances of the chromogen were measured at their respective wavelength of maximum absorbance against the corresponding reagent blank. The proposed methods have been successfully applied to the analysis of the bulk drug and its tablet dosage form. The methods have been statistically evaluated and were found to be precise and accurate.

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Regecová, Ivana, Jana Výrostková, František Zigo, Gabriela Gregová, and Mariana Kováčová. "Detection of Antimicrobial Resistance of Bacteria Staphylococcus chromogenes Isolated from Sheep’s Milk and Cheese." Antibiotics 10, no. 5 (2021): 570. http://dx.doi.org/10.3390/antibiotics10050570.

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Antimicrobial and multidrug resistance is detected in nonaureus staphylococci, including Staphylococcus chromogenes, which commonly causes intramammary infections. Recent clinical studies point to the presence of methicillin-resistant S. chromogenes. Therefore, this study aims to determine the prevalence of this species in samples of sheep‘s milk and cheeses made from them. Isolates were identified by polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF). A total of 208 staphylococcal isolates were identified. Of these, 18% were identified as S. chromogenes. The antimicrobial resistance of the identified isolates was determined using the agar dilution method against penicillin, ceftaroline, teicoplanin, gentamicin, erythromycin, tetracycline, and ofloxacin. The highest resistance was found to penicillin (95%), tetracycline (86%), and oxacillin (81%). The highest sensitivity was confirmed for gentamicin (55%). The study also confirmed the presence of methicillin resistant staphylococcal isolates (30%) based on the phenotypic manifestation of antimicrobial resistance and detection of the presence of the mecA gene. The study shows that the tested isolates (62%) were multidrug resistant. Resistance to two antibiotics was most often found (39%).

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Sheela, P., Malathi Shekar, Shrikrishna Isloor, et al. "Randomly amplified polymorphic DNA analysis of Staphylococcus chromogenes isolated from bovine and bubaline mastitis in Karnataka." January-2021 14, no. 1 (2021): 285–91. http://dx.doi.org/10.14202/vetworld.2021.285-291.

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Background and Aim: In recent times, non-aureus staphylococci (NAS) have emerged as the major organisms isolated from mastitis cases in dairy animals, with a predominance of Staphylococcus epidermidis and Staphylococcus chromogenes. As compared to Staphylococcus aureus, much less is known about the molecular types or the spatiotemporal epidemiology of these NAS species. In the present study, randomly amplified polymorphic DNA (RAPD) was employed to detect genetic polymorphisms, intraspecies diversity, and epidemiology of S. chromogenes strains (n=37) isolated from bovine and bubaline mastitis cases in the state of Karnataka. Materials and Methods: Thirty-seven S. chromogenes isolates (14 from bovines and 23 from bubaline) isolated from subclinical mastitis cases, from organized and unorganized sectors, were subjected to RAPD typing. Further, methicillin resistance was determined by cefoxitin disk diffusion method. Results: The amplified DNA fragments ranged from 150 to 3000 base pairs and yielded several RAPD profiles. Further analysis using Digital Image Correlation Engine correlation coefficient and UPGMA method showed that the 37 isolates could be classified into 12 distinct RAPD types (A to L) at 62% similarity (D=0.889). Four of the most predominant RAPD types, B, A, C, and E, in that order, and together, represented 65% of the isolates. High diversity was observed among the isolates both within farms and between geographic locations. Most of the isolates exhibited methicillin resistance. This is the first such report from India. Conclusion: In the absence of defined multilocus sequence type protocols or sufficient sequences available in the public domain, RAPD can be employed to determine genetic diversity of S. chromogenes isolates.

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Skalka, B. "Hemolytic Activity of Staphylococcus hyicus and Staphylococcus chromogenes." Acta Veterinaria Brno 57, no. 1-2 (1988): 3–11. http://dx.doi.org/10.2754/avb198857010003.

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Skalka, B. "Antibacterial Effects of Staphylococcus hyicus and Staphylococcus chromogenes." Acta Veterinaria Brno 62, no. 1-2 (1993): 39–47. http://dx.doi.org/10.2754/avb199362010039.

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Beraki, Elsa, and Torill Sauer. "Determination of HER-2 status on FNAC material from breast carcinomas using in situ hybridization with dual chromogen visualization with silver enhancement (dual SISH)." CytoJournal 7 (October 11, 2010): 21. http://dx.doi.org/10.4103/1742-6413.70968.

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During the last years, HER-2 status kits and protocols for chromogen visualization of hybridization signals have come on the market. The first generation using chromogen visualization used single color probes. The second generation, now emerging on the market, uses dual chromogen visualization. The aim of this study has been to test a new dual color chromogen kit (Ventana INFORM HER2 Dual Colour ISH Roche®) and compare the results with our in-house method(s). The material consisted primarily of cytological material from invasive breast carcinomas in 49 women. Dual SISH was done on all 49 cytological and histological specimens. The histological specimens were treated according to the manufacturer’s recommendations. The procedure was modified in several steps in order to adapt it to the cytological material. Hybridization failed in two cytological specimens. Dual SISH showed concordant results on cytological and histological material as to amplified/not amplified. The included cases had the same HER-2 expression in the invasive and the in situ components on histology. Four IDC showed HER-2 amplification (8.5%). Polysomy was found in two cases. All dual SISH results except for one concurred with the results of the in-house method(s) (1/47=2.1%). The dual SISH is suitable for cytological examination of HER-2 status. The protocol must be optimized for cytological material.

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Maguire, G. A., and M. W. Bannister. "The "chromogen oxidase" activity of bilirubin oxidase." Clinical Chemistry 33, no. 7 (1987): 1304. http://dx.doi.org/10.1093/clinchem/33.7.1304.

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Wu, Yifan, Yongqiang Wang, Huiming Yang, et al. "Resident bacteria contribute to opportunistic infections of the respiratory tract." PLOS Pathogens 17, no. 3 (2021): e1009436. http://dx.doi.org/10.1371/journal.ppat.1009436.

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Opportunistic pathogens frequently cause volatile infections in hosts with compromised immune systems or a disrupted normal microbiota. The commensalism of diverse microorganisms contributes to colonization resistance, which prevents the expansion of opportunistic pathogens. Following microbiota disruption, pathogens promptly adapt to altered niches and obtain growth advantages. Nevertheless, whether and how resident bacteria modulate the growth dynamics of invasive pathogens and the eventual outcome of such infections are still unclear. Here, we utilized birds as a model animal and observed a resident bacterium exacerbating the invasion of Avibacterium paragallinarum (previously Haemophilus paragallinarum) in the respiratory tract. We first found that negligibly abundant Staphylococcus chromogenes, rather than Staphylococcus aureus, played a dominant role in Av. paragallinarum-associated infectious coryza in poultry based on epidemic investigations and in vitro analyses. Furthermore, we determined that S. chromogenes not only directly provides the necessary nutrition factor nicotinamide adenine dinucleotide (NAD+) but also accelerates its biosynthesis and release from host cells to promote the survival and growth of Av. paragallinarum. Last, we successfully intervened in Av. paragallinarum-associated infections in animal models using antibiotics that specifically target S. chromogenes. Our findings show that opportunistic pathogens can hijack commensal bacteria to initiate infection and expansion and suggest a new paradigm to ameliorate opportunistic infections by modulating the dynamics of resident bacteria.

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YAMADATE, Shukoh. "Pigments and Chromogens used in Clinical Laboratory Testing." Journal of the Japan Society of Colour Material 90, no. 7 (2017): 244–48. http://dx.doi.org/10.4011/shikizai.90.244.

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Hájek, V., L. A. Devriese, M. Mordarski, M. Goodfellow, G. Pulverer, and P. E. Varaldo. "Elevation of Staphylococcus hyicus subsp. chromogenes (Devriese et al., 1978) to species status: Staphylococcus chromogenes (Devriese et al., 1978) comb. nov." Systematic and Applied Microbiology 8, no. 3 (1986): 169–73. http://dx.doi.org/10.1016/s0723-2020(86)80071-6.

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Kozłowski, Antoni. "Chromogen respiracyjny w nasionach grochu (Pisum satvum L.) [A respiratory chromogen in the seeds of pea (Pisum satvum L.)]." Acta Societatis Botanicorum Poloniae 14, no. 1 (2017): 49–55. http://dx.doi.org/10.5586/asbp.1937.003.

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Lange, Carla C., Maria A. V. P. Brito, José R. F. Brito, et al. "Uso de PCR e sequenciamento do rDNA 16S para identificação de bactérias do gênero Staphylococcus isoladas de mastite bovina." Pesquisa Veterinária Brasileira 31, no. 1 (2011): 36–40. http://dx.doi.org/10.1590/s0100-736x2011000100006.

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O objetivo deste trabalho foi identificar espécies de Staphylococcus (n=100) isoladas de mastite em rebanhos bovinos do Estado de Minas Gerais. Para esta finalidade foram utilizadas reações de PCR empregando oligonucleotídeos iniciadores descritos anteriormente para amplificar genes específicos de S. aureus (femA), S. intermedius (rDNA 16S) e S. hyicus (rDNA 16S-23S) e o sequenciamento do rDNA 16S. De acordo com as reações de PCR, 83 isolados foram identificados como S. aureus, 13 isolados como S. intermedius, dois como S. hyicus e dois isolados não foram identificados. Foram submetidos ao sequenciamento do rDNA 16S seis isolados identificados como S. aureus e os 17 restantes. Os seis isolados identificados como S. aureus confirmaram essa identificação. Dos outros 17 isolados, 13 foram identificados como S. chromogenes e quatro como S. hyicus, com similaridade igual ou superior a 99%. Baseando-se nos resultados da reação de PCR do gene femA e do sequenciamento do rDNA 16S, foram identificados 83 S. aureus, 13 S. chromogenes e quatro S. hyicus. Neste estudo os oligonucleotídeos iniciadores empregados na reação de PCR para S. intermedius não foram específicos, pois amplificaram também S. chromogenes; e os empregados na reação de PCR para S. hyicus não foram sensíveis, pois falharam na identificação de dois isolados de S. hyicus. A identificação definitiva das duas últimas espécies somente foi possível pelo sequenciamento do rDNA 16S.

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Andresen, Lars Ole, Peter Ahrens, Lise Daugaard, and Vivi Bille-Hansen. "Exudative epidermitis in pigs caused by toxigenic Staphylococcus chromogenes." Veterinary Microbiology 105, no. 3-4 (2005): 291–300. http://dx.doi.org/10.1016/j.vetmic.2004.12.006.

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Divakaran, Saratchandran A., and Anitha CT. "Estimation of ferulic acid from selected plant materials by Spectrophotometry and High performance liquid chromatography." Journal of Applied and Natural Science 13, no. 3 (2021): 815–19. http://dx.doi.org/10.31018/jans.v13i3.2732.

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Ferulic acid is an abundant phytophenolic compound present in plant cell wall. Ferulic acid possess anticancer, antioxidant, and anti-aging properties. A simple, sensitive and reproducible spectrophotometric method has been developed for quantitative estimation of ferulic acid from selected plant materials such as rice bran, wheat bran and bamboo shoot. The blue coloured chromogen obtained after the reaction was measured at wavelength of 718 nm for ferulic acid against the blank reagent. The chromogen obeyed linearity over the range of 1?g/ml - 8?g/ml. An HPLC method was also developed for the estimation of ferulic acid from selected plant materials.

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Reljic, R., M. Ries, N. Anić, and B. Ries. "New Chromogen for Assay of Glucose in Serum." Clinical Chemistry 38, no. 4 (1992): 522–25. http://dx.doi.org/10.1093/clinchem/38.4.522.

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Abstract We describe a colorimetric assay for glucose determination in human serum, with use of the chromogen 2-amino-4-hydroxybenzenesulfonic acid (AHBS), glucose oxidase, and peroxidase. With this assay, glucose concentrations less than or equal to 27.8 mmol/L can be measured in serum, with a sample/reagent volume ratio as low as 0.0025. The chromogen itself is easily soluble in water and does not require other components for the color change, making the reagent composition less complex. A single working reagent is used, and the reaction is completed within 10 min at 37 degrees C. The absorbance of the yellow reaction product is measured at 415 nm, and a blank sample measurement is not needed. The average analytical recovery of glucose in different human sera was 97.6%, with no significant interference of reducing compounds in serum. The results of the recommended procedure correlated well with those of the phenol/4-aminoantipyrine method of Trinder.

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SMÉKAL, F., H. RYŠÁNOVÁ, M. KONÍČKOVÁ-RADOCHOVÁ, and J. KONÍČEK. "Control of l-lysine biosynthesis with chromogene mutants Brevibacterium species M-27." Kvasny Prumysl 34, no. 6 (1988): 172–73. http://dx.doi.org/10.18832/kp1988026.

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Matkowskyj, Kristina A., Dan Schonfeld, and Richard V. Benya. "Quantitative Immunohistochemistry by Measuring Cumulative Signal Strength Using Commercially Available Software Photoshop and Matlab." Journal of Histochemistry & Cytochemistry 48, no. 2 (2000): 303–11. http://dx.doi.org/10.1177/002215540004800216.

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Currently available techniques for performing quantitative immunohistochemistry (Q-IHC) rely upon pixel-counting algorithms and therefore cannot provide information as to the absolute amount of chromogen present. We describe a novel algorithm for true Q-IHC based on calculating the cumulative signal strength, or energy, of the digital file representing any portion of an image. This algorithm involves subtracting the energy of the digital file encoding the control image (i.e., not exposed to antibody) from that of the experimental image (i.e., antibody-treated). In this manner, the absolute amount of antibody-specific chromogen per pixel can be determined for any cellular region or structure.

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Klimiene, I., M. Virgailis, A. Pavilonis, R. Siugzdiniene, R. Mockeliunas, and M. Ruzauskas. "Phenotypical and Genotypical Antimicrobial Resistance of Coagulase-negative staphylococci Isolated from Cow Mastitis." Polish Journal of Veterinary Sciences 19, no. 3 (2016): 639–46. http://dx.doi.org/10.1515/pjvs-2016-0080.

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AbstractThe objectives of this study were to determine the prevalence and antimicrobial resistance of coagulase-negative staphylococci (CNS) isolated from dairy cows with subclinical mastitis. Antimicrobial resistance in staphylococci were evaluated by breakpoint values specific to the species (EU-CAST). The presence of resistance-encoding genes was detected by multiplex PCR. A total of 191 CNS isolates were obtained. The CNS isolates were typically resistant to penicillin (67.4%), tetracyc-line (18.9%), and erythromycin (13.7%). CNS isolates (78.0%) were resistant to at least one antimicrobial compound, and 22.0% were multiresistant. The multiresistant isolates were predominantlyStaphylococcus chromogenes(28.6%),Staphylococcus warneri(19%) andStaphylococcus haemolyticus(14.3%). According to MIC pattern data, multiresistant isolates showed the highest resistance (p<0.05) rates to penicillin (85.7%), tetracycline (66.7%), and erythromycin (48.2%), but all of them were sensitive to daptomycin, oxacillin, qiunupristin/dalfopristin, and vancomycin.S. chromogenes (9.5%),S. haemolyticus(4.8%), andS. capitis ss capitis(2.4%) strains were resistant to methicillin; their resistance to oxacillin and penicillin was more than 8 mg/l. A high rate of resistance to penicillin was linked to ablaZ gene found in 66.6% of the isolated multiresistant CNS strains. Resistance to tetracycline via thetetK (38.1%) gene and penicillin via themecA (23.8%) gene were detected less frequently. GenemsrAB was responsible for macrolides and lincosamides resistance and detected in 28.6% of the CNS isolates. Antimicrobial resistance genes were identified more frequently inS. epidermidis,S. chromogenes, andS. warneri.

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Kemp, P. D., and J. E. Scott. "Ehrlich chromogens, probable cross-links in elastin and collagen." Biochemical Journal 252, no. 2 (1988): 387–93. http://dx.doi.org/10.1042/bj2520387.

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(1) Proteolytic digests of tissue elastin contain material which reacts with dimethylaminobenzaldehyde in acid solution (Ehrlich's reagent) to give a cherry-pink colour. This Ehrlich chromogen(s) [EC(s)] is similar to but not identical with EC(s) previously demonstrated in tissue collagens [Scott, Hughes & Shuttleworth (1979) Biosci. Rep. 1, 611-618]. Both ECs react with diazonium salts in acid to give coloured products. (2) Diazobenzene linked via a phenolic ester to polyacrylamide beads (Biogel P10) has been used to absorb ECs specifically and almost quantitatively from proteolytic digests. The coupled deeply coloured azo-EC-peptides were then recovered after mild alkaline cleavage from the support and purified by gel chromatography. (3) Using 15N-labelled NaNO2, the collagen azo-EC-peptides were prepared, and 15N abundance measured therein. The molar absorption coefficient of the azo-EC group was calculated (18,700) based on the assumption that each azo-EC group contained one 15N atom. (4) Collagen azo-EC-peptides contained glucose and galactose, whereas elastin azo-EC peptides did not. The amino acid patterns of the two peptides were quite different, the former being rich in polar amino acids, the latter containing much alanine. The patterns were compatible with an origin from the cross-linking regions of collagen and elastin respectively. (5) Quantitative (molar) comparisons of the azo-EC group content with amino acid, amino end-group and sugar contents, and azo-EC peptide molecular mass, suggest that a structure is present in the collagen azo-EC-peptides containing two EC groups shared between four peptide chains. Three peptide chains probably meet at each (cross-linking) EC group. (6) Based on this structure, about 15% of adult bovine skin collagen contains EC groups.

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KEMP, P. D., and J. E. SCOTT. "Ehrlich chromogens, probably cross-links, in elastin and collagen." Biochemical Society Transactions 15, no. 4 (1987): 711. http://dx.doi.org/10.1042/bst0150711.

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Mikheev, Yu A., L. N. Guseva, and Yu A. Ershov. "The optical properties of triphenylmethane dye molecules and chromogens." Russian Journal of Physical Chemistry A 82, no. 9 (2008): 1580–88. http://dx.doi.org/10.1134/s003602440809032x.

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Stankov-Jovanovic, Vesna, Violeta Mitic, Marija Ilic, Ljuba Mandic, and Snezana Nikolic-Mandic. "Enzymatic kinetic method for determination of propranolol hydrochloride in pharmaceuticals based on its inhibitory effect on cholinesterase." Chemical Industry 66, no. 5 (2012): 677–84. http://dx.doi.org/10.2298/hemind120128032s.

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Propranolol, a widely used beta-blocker, inhibits the reaction of enzyme cholinesterase hydrolysis. Measurements of the hydrolysis rate differences between and inhibited reactions, allows the development of a kinetic method for its determination. Both systems, enzyme-substrate-chromogen and enzyme-substrate-chromogen-inhibitor, were characterized through biochemical kinetic parameters (KM = 0.326-0.330 mmol/L; Vmax = 40-42.99 ?mol/Lmin), inhibition type was recognized as competitive, and inhibition constant, Ki, was determined to be 22.60 ?mol/L. The detection and quantification limits were calculated as 0.004 and 0.0136 ?mol/L, respectively. Accuracy and precision of proposed methods were tested. Proposed method is characterized with good sensitivity, selectivity, simplicity and rapidity, thus it is convenient for clinical applications.

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Journal articles on the topic 'Chromogène'

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