Search

Farb- und Helligkeitsunterschiede an glatten Sichtbetonflächen werden von einer Vielzahl von Einflussfaktoren beeinflusst. In der Planungsphase von Sichtbetonbauteilen wird die Farbe zumeist indirekt z. B. durch Verweis auf vergleichbare Bauwerke oder über Erprobungsflächen aus Beton eingegrenzt. Eine objektive und quantitative Festlegung findet jedoch nicht statt. Im Gegensatz dazu wird in vielen anderen Industriezweigen, wie z. B. der Automobil- oder Lebensmittelindustrie aber auch bei der Zementherstellung, die Lichtspektroskopie bzw. Farbmessung bereits erfolgreich zur quantitativen Farbmessung für Qualitätssicherungszwecke eingesetzt. Im vorliegenden Beitrag werden Einflüsse der Ausgansstoffe sowie einzelner betontechnologischer Eigenschaften auf die resultierende Farbe von Sichtbetonflächen systematisch und quantitativ mittels Lichtspektroskopie ermittelt und bewertet. Ferner wird die prinzipielle Eignung des Messverfahrens zur Anwendung in der Planungsphase glatter Sichtbetonflächen diskutiert., Colour and luminance differences on exposed concrete are influenced by a large number of factors. In the planing phase the colour is usually specified by referencing to other – similar – structures or by providing hand samples. However, an objective and quantitative assessment does not take place. In contrast, in many other industries such as automotive or food industry but also in cement production, the light spectroscopy or colour measurement is already successfully used for quality control purposes with both colour and luminance being quality criteria. In the present paper the influence of the raw materials and concrete properties on the resulting colour of exposed concrete surfaces is systematically und quantitatively determined and evaluated by light spectroscopy. Furthermore, the application of the measuring method for use in the planning phase of smooth exposed concrete surfaces is evaluated.

Many applications (apps) for ophthalmic solutions, including colour vision tests, are currently available. However, no colour vision test app has been evaluated through clinical trials on a tablet PC.Using standard test conditions and a tablet pc (iPad2®), colour vision tests were performed with 19 Velhagen/Broschmann/Kuchenbecker colour plates and an HMC anomaloscope. The plates were alternately presented at first in a book (pigment colour plates) and then in a tablet PC (iPad®). A total of 77 volunteer subjects were examined. 62 subjects were colour normal and 15 male subjects had a colour vision deficiency. The coincidence and the 95 % confidence intervals were determined.The average age of all subjects (n = 77) was 42.8 ± 16.9 years. The mean near visual acuity of all subjects was 0.99 ± 0.15. The coincidence of the results of all subjects between books and tablet PC was 88.0 %. The 95 % confidence interval ranged from 81.6 to 89.6 %. In the group of subjects with colour vision deficiency (n = 15), the coincidence was 83.3 %. The 95 % confidence interval ranged from 78.4 to 87.3 %. In the group of subjects without colour vision deficiency (n = 62), the coincidence was 89.1 %. The 95 % confidence interval ranged from 87.1 to 90.8 %. The overlap of error numbers of colour normal subjects and colour vision deficiency subjects was 2 errors with the book and 5 errors with the tablet pc.Testing colour vision using book and tablet pc only gives roughly comparable results. However, separation with the book was better and the colour plates differed in validity. For this reason, only some of the colour plates could be used on a tablet PC.

The overexposed photograph of a dress caused a worldwide media hype in February 2015. The picture of the dress was posted on a social site with the question of which colour it was. Markedly different views on the color were voiced and strongly defended.The phenomenon is presented in this article, the actual color of the dress is clarified and a discussion on why such conflicting views were held is presented.It becomes clear that in the perception of colors we unconsciously but appropriately take the lighting situation into consideration. Because we additionally name colors categorically, small differences in hue and illumination can lead to an assignment to very different categories.

For the first time the considered unstable α,α-diformyldipyrrins are efficiently synthesized and isolated. These compounds and derivatives have proven to be extremely reliable and interesting complexometric indicators of a new generation. The preparation of the ligand by the condensation of the α,α-diformyldipyrrins with hydrazides, like semicarbazide, or other primary nitrogen compounds is very efficient. The high extinction coefficient (up to 10^5 L/mol/cm), the high binding constants (up to > 10^12 L/mol) and the shift of the absorbance (50 -200 nm) enables the identification by UV/Vis spectroscopy at very low concentrations. In addition, the identification of many cations is possible with the naked eye. Another interesting feature is the selective coordination of cations among others weaker binding cations.The synthesized planar meso-alkyldipyrrins with three long chain alkyl groups were used for the studies on graphite surfaces. The dipyrrin structure allows changes in the geometry and could allow a switchable surface. With STM images this change is visible through a different surface structure. The different surface structures can be obtained by an irreversible rotation of both pyrroles by 180°.

Up to now, several examinations are necessary to identify early glaucoma. It is also possible to analyse the peripapillary retinal nerve fibre layer thickness by means of OCT. The loss of retinal ganglion cells can be measured by pattern ERG, therefore this method could be used for the detection of early glaucoma. This study compares the results of the blue light-pattern ERG with the Stratus OCT for glaucoma early recognition.We studied 30 healthy test persons, 20 patients with glaucoma and 20 patients with suspected glaucoma. Each group was examined using eye pressure measurements, funduscopy, perimetry, pachymetry und analysing the retinal nerve fibre layer by the Stratus OCT. The diagnostic work-up was completed by the pattern ERG and an upgrade with a blue light filtering glass. The results of the blue light-pattern ERG and the OCT ("healthy" or "pathological") were compared in a cross table and the agreement between these two raters was measured by the Cohen's kappa coefficient.Pattern ERG and blue light-pattern ERG decrease with advancing age. After developing an age-matched calibration graph we defined standard values up to the age of 56 years. All included subjects were classified by Stratus OCT and blue light-pattern ERG as healthy. We recognised a significant reduction of the retinal nerve fibre layer thickness and the amplitude in the pattern ERG in the cluster of glaucoma patients. For most of them, a blue light-pattern ERG could not be recorded. Nine out of 40 glaucoma suspect eyes were judged as "pathological". Regarding the amplitudes of the blue light-pattern ERG 25 of 28 eyes under suspicion of glaucoma were assigned as "healthy". With the aid of the cross table we estimated a Cohen's kappa of 0.4. The sensitivity of the blue light-pattern ERG was computed to be 70 % and the specificity to be 97.7 %. For the OCT we calculated the sensitivity to be 50 % and the specificity to be 100 %.The blue light-pattern ERG correlates in 87 % of our cases with the OCT. Healthy test persons are certainly identified just as well as definitely glaucomatous patients. To distinguish people suspected of early glaucoma the blue light-pattern ERG can be used as an additional, fast and economic diagnostic procedure.

There is uncertainty in ophthalmology concerning the quality and spectral transmission of light of so-called blue filter intraocular lenses (IOL). Clinical users have noticed that such IOL's appear to have different color intensities. The discussion on medical changes by means of such IOL's is dependent on the real light transmission of these IOL's. To add some objective data we compared these IOL's by systematic transmission measurements and observed technical differences of diffraction and geometry as well as transmission differences. The result gives objective indications that differences between blue filter IOL's from different manufacturers are important and are detailed in this paper.

Gegenstand dieser Arbeit war die Untersuchung von Verbindungen unterschiedlicher Substanzklassen und deren mögliche Anwendung als Pigment, um toxikologisch bedenkliche Farbmittel zu ersetzen. Die meisten der betrachteten Stoffe waren bereits aus der Literatur bekannt, die farblichen Eigenschaften jedoch nicht näher erforscht. Ziel war eine saubere, präparativ leicht zugängliche Synthese der Verbindungen mittels Festkörperreaktion und deren farbmetrische Analyse. Die Proben wurden mit Hilfe von Röntgenbeugung und Reflexionspektroskopie untersucht. Anhand der bestimmten Farbparametern des CIELab-Systems konnte ein erster Eindruck der optischen Eigenschaften der Produkte gewonnen werden. Bei dem ersten Themengebiet handelte es sich um Sn-haltige oxidische Pigmente, die eine Vielzahl auch strukturell unterschiedlicher Substanzen umfassten und deren Produkte im orange-roten Farbbereich zu finden waren. Untersucht wurden die Verbindungen M2-xBixSn2O7 (M=Y, La), Sn2TiWO7, Sn2-xMxTiNbO6-xF1+x (M=Na, K) und xZnO*ySnO*zTiO2 von denen vor allem die letzten beiden gute Farbwerte lieferten. Des Weiteren wurden Versuche zur Stabilisierung von Bi2O3-Modifikationen bei Raumtemperatur durch Dotierung durchgeführt. Als substituierende Elemente kamen dabei Y3+, Ce4+, Zr4+, Nb5+, Ta5+, V5+, W6+ und Mo6+ zum Einsatz. Speziell die durch Umsetzung mit Cer, Zirkonium und Niob erhaltenen gelb-orangen Produkte der β-Modifikation lieferten farblich interessante Ergebnisse. Zuletzt wurden Dotierungseffekte in dem Mn(V) enthaltenden Grünpigment Ba3Mn2O8 betrachtet. Hierbei wurde versuchsweise sowohl die Ba-Position mit Sr als auch die Mn-Position mit P substituiert. Koloristisch zeigte jedoch die unsubstituierte Verbindung die besten Eigenschaften. The aim of this work was the investigation of compounds from different substance classes and their potential application as pigment to replace colorants which are toxicologically harmful. Most of the observed substances were known from literature. However, the coloristic properties were not explored. The goal was an easily accessible synthesis of the compounds using solid state reactions and their colorimetrical analysis. The samples were analysed by X-ray diffraction and reflexion spectroscopy. The color coordinates of the CIELab system gave a first impression of the optical qualities of the products. The first topic was oxidic pigments containing Sn involving a variety of structurally different substances and with products that can be found in the orange-red color area. The compositions M2-xBixSn2O7 (M=Y, La), Sn2TiWO7, xZnO*ySnO*zTiO2 and Sn2-xMxTiNbO6-xF1+x (M=Na, K) were examined. First of all, the last two compounds have provided excellent color coordinates. Furthermore, experiments were conducted to explore the stabilization of Bi2O3 modifications at room temperature by doping. Y3+, Ce4+, Zr4+, Nb5+, Ta5+, V5+, W6+ and Mo6+ were used as substitutes. In particular, the experiments with cerium, zirconium and niobium to get the β-modification leading to yellow-orange products provided results that were interesting regarding their color properties. Lastly, doping effects in the green pigment Ba3Mn2O8 containing Mn(V) were examined. It was tried to substitute the Ba position with Sr and the Mn position with P. However, the non-substituted compound has shown the best coloristic properties.

In clinical practice, several techniques for the evaluation of colour vision deficiencies are well established. Most of them are designed for the detection of congenital or pathological changes. Due to the narrow-banded light sources, used in monitors or anomaloscopes, the human gamut can be addressed only in part. With these set-ups, the impact of coloured filters on colour vision such as blue light filtering intraocular lenses cannot be investigated precisely.The technique is based on the visual matching of colour differences between two halves of a test field. The colours are generated by mixing seven types of LEDs. A transparent, vertically divided circular test field is retro-illuminated with this light using optical fibres and projection optics. An ocular optic assures the unaccommodated sight of the subject on the test field (size 2 degrees).The developed set-up presents freely adjustable colours in the form of continuous light spectra to examine the influence of filter materials on colour discrimination. A colour space can be generated which corresponds to that of human perception. The saturation and brightness of the light is adjustable. The subject has to decide if he can discriminate between the colours in the test field halves or not. Before the next colours are shown the subject is neutrally adapted by a neutral hue to provide different adaptation levels. The luminescence of the test field can be varied up to 1500 cd/m(2). The adaptive algorithm of the sequence is based on the SIAM method described by Kaernbach. Based on reference measurements, including 4 subjects with a congenital deficiency, it was shown that the discrimination thresholds at the characteristic confusing axes are significantly different than those with normal colour vision. Also, the impact of green laser goggles on the colour perception was determined. Due to the filter the thresholds in the vicinity of yellow (x = 0.4664; y = 0.4525) are reduced in the yellow-orange and cyan range and increased in the green-yellow and magenta range.With this set-up an objective instrument is available for clinical research in the field of individual human colour perception. It enables an accurate and detailed analysis of the impact of coloured filters as well as a quantitative detection of congenital anomalies. The adaptive algorithm allows short sequences and precise determination of colour discrimination thresholds.

In the 1990s, there was great optimism due to the development of devices for measuring tooth shade. The frequently not so simple, visual determination of the shade of a tooth was to be done with the aid of a device which recognizes the shade and describes it accurately by reference to a color chart. However, the skepticism towards such devices was also great. It is known that the color effect frequently differs strongly when comparing a tooth from the shade guide with a metal ceramic crown, despite identical shade designation. Anyone who considers visual shade determination to be inadequate and places his hopes in digital shade matching devices will be disappointed. It is the shade-generating structures of the metal ceramic and frequently of the veneer layers that turn out to be too thin which, despite correct shade selection, cause a different color perception. Such problems have been reduced decisively with the development of fracture-proof hard porcelain caps (Vita In-Ceram) with optical characteristics similar to teeth. In addition, the Vita System 3D-Master tooth shade system developed in 1998 by Vita in cooperation with Dr. Hall from Australia, leads the practitioner to a better understanding of the primary tooth shade characteristics of "brightness (value)", "color intensity (chroma)" and "color (wave length of the visible light, hue)". These two innovations allow a more accurate estimate of the basic shade of a natural tooth (reference tooth) and the imitation in the laboratory of its natural, shade-generating structures. If digital shade measurement supplements the visual shade estimate, then a further improvement can be expected--especially in the recognition of the basic shade. Qualitative descriptions of subjective shade measurement of a natural tooth and of its imitation in the dental laboratory by ceramics can be found frequently in professional journals and publications. With digital tooth shade matching devices, which apart from the color code of the color chart also reproduce exact, colorimetric values, such work processes can be recorded quantitatively and objectively. Reports about this type of controlled shade determination and generation are found rarely in the literature, which is surprising in view of the large number of tooth shade matching devices and dental ceramic systems available. In the present paper, the influence of the individual ceramic layers on color perception is measured and described under standardized conditions. The creation of the basic shade as it results from the composition of the various ceramic layers is traced with a spectrophotometer. The Vita In-Ceram Alumina infiltration ceramic and the VitaVM7 veneer ceramic were selected as the ceramic system. MHT-SpectroShade and Vita Easyshade were used as shade matching devices.

In this study, the influence of differently shaded substructures made of Y-TZP from different manufacturers (without, with 0.5 mm or 1.0 mm ceramic veneer with Vita VM9 Base Dentin) on the lightness, the saturation, and the color shade (= value, chroma, and hue) was measured and assessed with a spectral photometer (Easy Shade, Vita) on a clinical case in the mouth and on models of different color. Shading substructures made of Y-TZP facilitated adaptation to the basic shade and reduced the layer thickness of the veneer ceramic required to achieve the desired color. This should be done in the future as a matter of routine. In this way, tooth substance can be better conserved when preparing the teeth, and the esthetic result is not diminished. The material used for the production of the working models (plaster or plastic) should be tooth colored and in terms of lightness--analogous to the shading of the substructure--in order to facilitate clinical color measurement and quality control in the laboratory.

Oncological therapy strategies are increasingly concentrating on the causal, molecular changes involved in carcinogenesis. So called "smart drugs" such as antisense oligoneucleotide (AsON) can be used as specific inhibitors of individual genes. AsONs have shown their effectiveness in many studies. Clinical studies have demonstrated, however, that for many tumours the inhibition of a single gene is, due to multigenetic alteration, largely ineffective. The combination of AsONs with conventional chemotherapeutic agents is currently being investigated in phase III studies. In these studies, chemotherapeutic agents have been evaluated in cell culture together with AsON against the proliferation associated Ki-67 gene, as well as against the apoptosis associated bcl-2 gene via RT-PCR, immunochemistry and MTT cell viability assay. For both AsONs, significant target inhibition was achieved in cell culture with a high target gene expression. The prior treatment of tumour cells with bcl-2 AsON significantly increased the effectiveness of chemotherapy, while the combination of conventional chemotherapeutic agents with Ki-67 AsON showed no synergistic effects.

Over the past years the market share of whitening dentifrices has been increasing. The aim of this parallel, randomized, double-blind clinical trial was to assess the efficiency of three commercially available tooth whitening dentifrices. Thirty-six subjects with extrinsic tooth stain (A3 and darker) were randomly assigned to three groups (A, B, C) of twelve subjects each. Group A brushed their teeth twice daily with Durodont medical fresh and white (RDA 70), Group B with Friscodent Zahnweiss (RDA 87) and Group C with a combination of Durodont Zahnweiss intensiv (RDA 166) and Durodont medical fresh and white. At baseline and after four and eight weeks the color of the anterior teeth was evaluated using a VITAPAN classical color shade and a special colorimeter (Homeba). The colors of the shade guide were arranged and nummerized by value. After four and eight weeks of use each dentifrice showed a significant whitening effect compared to baseline (por = 0.05). There were, however, no significant differences between the groups. Moreover both methods showed similar results. Thus, the results support a significant "whitening" effect of all three dentifrices.

Dialkylamine drugs desipramine, propanolol, pindolol, alprenolol and metoprolol 4a-e react with 2,3-dichloro-1,4-naphthoquinone (2) and acetaldehyde to give red coloured 2-dialkylamino-3-chloro-1,4-naphthoquinones 5a, b, d, e, blue coloured 2-dialkylamino-vinyl-3-chloro-1,4-naphtho-quinones 1a-e and bluish green coloured 2-dialkylamino-butadienyl-3-chloro-1,4-naphthoquinones 6b-e. The colour products are isolated by column chromatography.

In der vorliegenden Arbeit wurde die Einsatzfähigkeit der Farbmessung zur objektiven Bestimmung von Farbabweichungen im Fettgewebe von Schweineschlachttierkörpern geprüft. Als Ergebnis konnte ein Verfahren für die sichere, schnelle und somit kostengünstige Ikterusdiagnostik in der Schweineschlachtung entwickelt werden. Die Auswertung der Fleischuntersuchungsstatistik eines Schlachthofes von 1994 bis 2000 zeigte, dass 4,45% aller untauglich beurteilten Schweineschlachttierkörper wegen der Ausprägung eines Ikterus verworfen wurden. Bei der visuellen Beurteilung unmittelbar nach der Schlachtung wurden 11,57% davon falsch positiv beurteilt. Diese Beurteilung wurde nach 24-stündiger Beschlagnahme und erneuter Beurteilung korrigiert. Diese Studie zeigte, dass der Ikterus einen nicht zu unterschätzenden Anteil am gesamten Verwurf hat. Die Entwicklung und Erprobung eines objektiven Verfahrens zur Ikterusdiagnostik ist damit gerechtfertigt. Als objektive Verfahren zur Farbmessung stehen derzeit die Spektrophotometrie und das Dreibereichsverfahren zur Verfügung. Beide Verfahren wurden auf ihre Tauglichkeit für die Ikterusschnelldiagnose getestet. Die spektrophotometrischen Untersuchungen erfolgten mit dem Spektrophotometer CM 100 der Firma Shimadzu. Die Farbmessungen nach dem Dreibereichsverfahren wurden mit dem Chromameter CR 300 der Firma Minolta durchgeführt. In den Vorversuchen zur Spektrophotometrie wurden die Proben der zu untersuchenden Pigmente nach der AVVFlH (Alkohol/Ether-Probe) aufbereitet. Die Spektrophotometrie ermöglicht die Unterscheidung von zweigipfligen Spektren der Karotine und eingipfligen Spektren der Gallenfarbstoffe. Für die Entwicklung eines Schnelltests ist die Spekrophotometrie ungeeignet, da die Probenaufbereitung zu zeit- und kostenintensiv ist. Der Einsatz der Spektrophotometrie könnte zur Objektivierung der Amtlichen Methode beitragen, da die zu untersuchenden Lösungen einer exakten Messung unterworfen und nicht subjektiv beurteilt werden. Die Vorversuche mit dem Chromameter CR 300 der Firma Minolta zeigten, dass eine Unterscheidung der Pigmente mittels Farbmessung schnell und ohne zusätzliche Laborarbeit möglich ist. Nachfolgende Messungen an tauglich beurteiltem Schweinefettgewebe von je 54 Mastsauen, Mastborgen und Zuchtsauen zeigten unterschiedliche Farbparameter für die einzelnen Gruppen. Aus den gemessenen Werten von Mastsauen und Mastborgen wurde folgender Mastschwein-Standard für die Farbe von Schweinefettgewebe (Mittelwert ± Standardabweichung) ermittelt: L* = 67,81 ± 2,55; a* = 2,43 ± 0,66; b* = 2,93 ± 0,69; C* = 3,85 ± 0,76; H* = 50,18 ± 8,78. In nachfolgenden Untersuchungen wurden 54 Schlachttierkörper von Ebern, einschließlich Binnenebern und Zwittern, gemessen. Eberfett ist mit einem Helligkeitswert von L* = 78,85 wesentlich heller als taugliches Fettgewebe. Es kann somit sicher von diesem unterschieden werden. Die farbmetrischen Untersuchungen von 54 ikterischen Schlachttierkörpern ergaben, dass sich ikterisches Fett sicher in allen Farbwerten (Mittelwert ± Standardabweichung) von tauglichem Fett unterscheidet: L* = 77,24 ± 3,05; a* = 0,92 ± 1,14; b* = 8,48 ± 3,00; C* = 8,64 ± 3,00; H° = 82,83 ± 9,36 Nur im Vergleich mit Eberfett weist es einen ähnlichen Wert für die Helligkeit L* auf. Zur Anwendung der Farbmessung als Ikterusschnelltest wurden aus den o.g. Farbwerten Grenzwerte für die Helligkeit L* = 72,3 und den Gelbanteil b1* = 4,6 (mit Identifikation der Eber) oder b2* = 5 (ohne Identifikation der Eber) berechnet. Ein Ikterus liegt vor, wenn beide Grenzwerte überschritten werden. Die Farbmessung mit dem Chromameter CR 300 der Firma Minolta ist in Verbindung mit den o.g. Grenzwerten zur Durchführung eines Ikterusschnelltestes an schlachtfrischen Schweineschlachttierkörpern geeignet. Weitere Untersuchungen zeigten den Einfluss von technologischen Faktoren wie Zeit, Kühlung und schlachtbedingte Auflagerungen auf die Fettfarbe., In the thesis presented the use of colorimetry for objective determination of discolorations of fat tissue in pig slaughter carcasses was tested. The result was the development of a secure, fast and cost saving method for diagnosis of jaundice in pig slaughtering. The analysis of official meat inspection statistics from one slaughterhouse covering the years from 1994 to 2000 showed that 4.45 % of all condemned pig slaughter carcasses were classified as not suitable for human consumption due to the diagnosis of jaundice. In the visual inspection directly after slaughtering 11.57 % were judged as false positive results. After confiscation for 24 hours this judgement was corrected in a repeated inspection of the carcasses. The analysis showed, that jaundice presents an important proportion of the condemnations, these justifying the development and testing of an objective method for jaundice diagnosis. Spectrophotometry and colorimetry by tristumulus measurement are the present objective methods for colorimetry. Both methods were tested for use in the diagnosis of jaundice. The spectrophotometrical investigations were carried out using the Shimadzu Spectrophotometer CM 100. The colorimetrical measurements were made with the Minolta Chromameter CR 300. In pre-tests for spectrophotometry the samples of pigments to be investigated were prepared following the General Administrative Order for Meat Hygiene (AVVFlH) using the alcohol-ether-test-kit. Spectrophotometry allows to differentiate the two-peak-spectra of carotins from the one-peak-spectra of bile-pigments. As the preparation of samples involves costs and time the spectrophotometry is not suitable for the development of a fast test. However it is possible to objectify the official method by exact measurement of solutions in alcohol-ether-tests. In pre-tests with the Minolta Chromameter CR 300 was found that it is possible to differentiate the pigments by colorimetry very fast and without laboratory peparation. In fat tissues of 54 fattened sows, 54 fattened castrated males and 54 breeding sows, wich were suitable for human consumption, different color-parameters (L*a*b* and L*C*H°) in these diffent groups could be demonstated. From parameters of fattened sows and castrated males a color standard of pig fat tissue (mean ± standarddeviation) was calculated: L* = 67,81 ± 2,55; a* = 2,43 ± 0,66; b* = 2,93 ± 0,69; C* = 3,85 ± 0,76; H* = 50,18 ± 8,78 In subsequent investigations the fat tissues of 54 uncastrated males, including cryptorchids and hermaphrodites were measured. These fat tissues with a brightness parameter of L* = 78,85 were brighter than suitable fat tissue. There a differentiation is possible. The colorimetrical investigation of 54 slaughter carcasses with jaundice showed, that icteric pig fat is different from suitable pig fat in all color- parameters (mean ± standarddeviation): L* = 77,24 ± 3,05; a* = 0,92 ± 1,14; b* = 8,48 ± 3,00; C* = 8,64 ± 3,00; H° = 82,83 ± 9,36 Only the fat of uncastrated males is similar in brightness L*. By using the colorimetry as fast test for the diagnosis of jaundice limits for brightness L* = 72,3 and yellowness b1* = 4.6 (with identification of uncastrated males) or b2* = 5 (without identification of males) were calculated. It showed that jaundice is present when the color parameters are higher than both limits. The colorimetry using the Minolta Chromameter CR 300 in combination with the calculated limits is useful as fast test in pig fat for the diagnosis of jaundice in fresh slaughtered carcasses. Further investigations showed the influences of technological factors such as time, cooling and residues of slaugtering on fat color.

The reason of unreproducible data under diagnosis and therapy with radioiodine should be elucidated.The iodine content of the capsules was tested by a colorimetric method and by activation analysis. Radiochemical purity was determined by HPLC and by electrophoresis. Solubility of the capsules was investigated under different conditions.The iodine content of the capsules varied between 0.8 and appr. 100 micrograms/capsule. The radiochemical purity of the capsule iodine varied between 75% and 99.5% (main contamination: iodate). The solubility of the capsules differed.Additional non-radioactive iodine in the therapy capsules could be one reason of the reduced radioiodine-uptake under therapy.

Besides statistical quality control, quality control based on patient specimens is an important tool for quality enhancement and thus for an increased diagnostic certainty in laboratory medicine. One of three possibilities of plausibility judgement is the control of extreme results, that is alert and absurd value check. The aim of our study was to look for extremely high or low findings of the most frequently examined clinical-chemical parameters, to scrutinize their validity according to clearly defined criteria and to find out the underlying actual clinical situations and diseases. In this publication only the results for the electrolytes are discussed. Retrospectively the most extreme values of all results for serum sodium, potassium and chloride concentrations of a 21-month interval were extracted in a large university hospital. The clinical situation was then evaluated by reading the medical reports of these patients. The validity of the findings was judged by previously defined criteria and rated as confirmed, questionable and not confirmed. In all cases the survival time was determined. The most extreme confirmed results were for sodium 191 and 100 mmol/l, for potassium 9.0 and 1.3 mmol/l and for chloride 138 and 65 mmol/l. All these findings were compatible with life, at least for several hours. Even if it is probably impossible to give generally valid extreme ranges. Nevertheless our results should certainly have practical importance in absurd and alert value check.

The determination of fructosamine in serum of healthy newborns, children and adolescents by a new colorimetric method leads to an age-dependent reference range. Correction of the values for total protein yields a median of the results, which is not dependent on age and the upper limit of the reference range is not significantly different from that of healthy adults; this does not hold true for referral to albumin. As the half-life time of glycated serum proteins is shorter (mean 20 days) than that of hemoglobin A1c, fructosamine can provide useful additional informations about the diabetic control of children and adolescents (medium-term record of blood glucose).

The Ni2+/S2O4(2-)-test makes semiquantitative assessment of cystine concentration in urine possible. The reaction principle of the method is based on the formation of a nickel/cysteine/sulfide complex of brown colour. Visual test evaluation is done by classifying the colour intensity of the sample/reagent mixture according to an exact colour shade. Each colour shade on a colour reference table is correlated to a certain range of cystine concentration. Cystine determination is described in detail for two ranges (0.60 and 1.25 mmol/l).

Three methods of the determination of insulin in serum were optimized in order to determine low concentrations of this analyte reliably (Method I: enzymatic after acidic hydrolysis of inulin; Method II: by anthrone/sulfuric acid reagent; Method III: by cysteine/tryptophan reagent). The interfering reaction of glucose in the methods I and II was avoided by the preincubation of samples with glucose oxidase/catalase reagent. The detection limit of all three methods was below 5 mg/l and the within-run precision amounted to values below 5%. Method I and II gave identical results. In comparison with these two methods, method III resulted in inulin values by about 8% lower, because inulin, depending on the lot used, contained alkali-labile fractions which were destroyed during the sample preparation. Method II is recommended for routine measurements because of its an analytical reliability and its cost-effectiveness.

The degree of nonenzymatic glycation of serum proteins was estimated in 500 nondiabetic subjects and in 124 Type 2 diabetic out-patients. The values were evaluated in relation to a DMF calibration curve, a secondary glycated protein standard and to serum protein concentrations. Neglecting the evaluation with respect to the protein concentration 0.4% of the samples from nondiabetics and 9% from diabetic patients would have been incorrectly interpreted. The fructosamine values from nondiabetic subjects showed a Gaussian distribution. The use of secondary protein standards is a premise to a widespread application of the fructosamine assay in diabetic care. The calibration of such secondary glycated protein standards results in some problems when using DMF protein mixtures as primary standards, because albumin preparations from the same or different suppliers gave variable standardization curves.

The clinical aspects of the excretion of beta-N-acetylglucosaminidase (beta-NAG, EC 3.2.1.30) in urine of type I and type II diabetics with and without nephropathy are evaluated. Correlation between concentration of albumin and of beta-NAG activity in urine is determined and the circadian rhythm of beta-NAG excretion in urine is examined, the indication of glomerular and tubulointerstitial damage is discussed. Longitudinal studies should demonstrate, whether an increased beta-NAG activity in urine of diabetics with normoalbuminuria is an indicator of nephropathy or a predictor of nephropathy if raised albuminuria is observed.

Delayed diagnosis, apparently due to insufficient knowledge of partly simple methods of cystine determination and their practical application, is often a particular problem in the treatment of cystine lithiasis. The present paper gives a survey of a variety of laboratory methods to determine cystine in the urine both qualitatively and quantitatively. Their applicability in various diagnostic situations is discussed. In clinico-chemical routine, colorimetric cystine determinations using Brands test, but partibularly the nickel/dithionite reagent, is an established and reliable laboratory method. Possibilities of its use as quick screening assays are described.

Reference ranges were evaluated for a new colorimetric method for the determination of fructosamine in serum. The reference group was composed of 1114 non-diabetics of both sexes including children. Reference values are only slightly affected by age and sex. In the course of childhood to adolescence fructosamine values raise and finally stabilize in adults. The small differences between both sexes have no effect on the interpretation of clinical results. Relating fructosamine values to albumin or total protein has little impact on the distribution of the values when protein values were within the reference range.

The measurements were accomplished by using an experimental setup in which an intestinal loop with adjacent mesentery of an anaesthetized rat was immersed in a buffer-containing cuvette. After i.v. injection of Evans' Blue (EB) the extravasation of the dye, which is bound to plasma albumin, was measured colorimetrically. From the curves recorded it could be derived that after i.v. injection of 2 or 4 g or infusion of 6 g/h glucose (Gk) per kg body weight the permeation of albumin-bound EB was increased by a factor of about 1.9, 3.1 and 2.0 respectively. As mechanism of these effects it is assumed that Gk (but also galactose and saccharose in control experiments) act by osmotically shrinking the endothelial cells and opening their junctions.

The between-run precision of the Liebermann-Burchard reaction modified by Watson was, in our laboratory, 2-3%, the within-run coefficient of variation was 1-2%. The between-run precision of the enzymatic test was 3-4%, the within-run coefficient of variation was 3%. The regression analysis of 92 serum specimens from patients was y = -17.31 + 1.04 chi, the coefficient of regression was r = 0.996. Interlaboratory trials of serum cholesterol were studied in the normal and pathological range. Lyophilized samples of serum prepared commercially and from fresh specimens from patients were analysed by the method of Liebermann-Burchard as well as by the enzymatic procedure. Acceptable results estimated by Liebermann-Burchard were obtained in the different laboratories after using a common standard of cholesterol. The coefficient of variation of the enzymatic test in the interlaboratory trial was higher in comparison to the Liebermann-Burchard reaction. Methodological difficulties of the Liebermann-Burchard reaction are discussed and compared with the specific, enzymatic assay.