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Biomedical subjects

G Englert

Publications and source records attributed to G Englert.

At least 19 recordsLinked to original sources
PubMed2002

Biofilm development in down flow anaerobic fluidised bed reactors under transient conditions.

Biofilm development onto polypropylene particles (<4 mm) was studied in a laboratory-scale down flow anaerobic fluidised bed reactor. The reactor was fed with a synthetic solution containing sucrose and nutrients, and operated at 35 degrees C during 65 days at 44% bed expansion rate and 36 h HRT. Scanning electron microscopy (SEM) monitored the biofilm development. Initial adhesion occurred within the first 6 hours and after day 44 biofilm structure was complete. The presence of attached cells morphologically similar to Methanotrix bacilli and Methanosarcina sp. was observed by Scanning Electron Microscopy (SEM). The biofilm and the carrier surface roughness were measured by atomic force microscopy (AFM) and yielded 9.1 and 75 nm respectively. Results also showed good correlation between the SEM characterisation and the conventional anaerobic reactor parameters.

Bacteria, Anaerobic↗
PubMed2001

[More power for patients: the patients' forum--a joint platform for the medical profession and patient self-help groups].

New ways of cooperation between doctors and representatives of patients are followed with the help of the patients' forum which was founded on the initiative of the German Medical Association. Members of the German Association 'Help for the Handicapped People', the 'Forum of the Chronic Ill and Handicapped People' of the 'Equal Charitable Organisation' (Paritätischer Wohlfahrtsverband), the 'German Association of Self-Help Groups' as well as representatives of the committees and the management of the German Medical Association and the National Association of Statutory Health Insurance Physicians form the patients' forum. The major aim of this cooperation is to discuss the possibilities and the ways to improve the quality in health care. A direct participation of patients' representatives is for the moment planned in the evaluation of the quality of medical information for the lay public. In cooperation with the Agency for Quality in Medicine--a joint institution of the German Medical Association and the National Association of Statutory Health Insurance Physicians--the quality of information on health care that is published in the internet should be examined. The patients' information service which was developed by the Agency for Quality in Medicine and is found under www.patienten-information.de is the basis for this examination.

Chronic Disease↗
PubMed1996

Isolation and structural elucidation of the predominant geometrical isomers of alpha-carotene.

The recent development and application of a polymeric C30 stationary phase have given unique separations of cis-trans carotenoid isomers in reversed-phase (RP) liquid chromatography (LC) owing to the exceptional shape selectivity of this stationary phase. In the present research, several geometrical isomers of alpha-carotene were at least partially resolved from a photo-isomerized mixture when chromatographed on a 3-microns polymeric C30 column. Double bond configurations of the five predominant alpha-carotene peaks, as isolated on a semi-preparative C30 column, were unambiguously assigned using 1H nuclear magnetic resonance (NMR) spectroscopy, giving the following order of elution: 13-cis, 13'-cis, all-trans, 9-cis, and 9'-cis geometrical forms. Electronic absorption spectra for these isomers were in agreement with the identification of peaks. The alpha-carotene isomers separated and identified herein had not been previously resolved in RPLC. Confirmation of the structures of geometrical alpha-carotene isomers will aid further studies on the possible physiological roles of these compounds in biological tissues.

Carotenoids↗
PubMed1995

Isolation, structural elucidation, and partial synthesis of lutein dehydration products in extracts from human plasma.

All-E-(3R,6'R)-3-hydroxy-3',4'-didehydro-beta,gamma-carotene (anhydrolutein I) and all-E-(3R,6'R)-3-hydroxy-2',3'-didehydro-beta,epsilon-carotene (2',3'-anhydrolutein II) have been isolated and characterized from extracts of human plasma using semipreparative high-performance liquid chromatography (HPLC) on a C18 reversed-phase column. The identification of anhydroluteins was accomplished by comparison of the UV-Vis absorption and mass spectral data as well as HPLC-UV-Vis-mass spectrometry (MS) spiking experiments using fully characterized synthetic compounds. Partial synthesis of anhydroluteins from the reaction of lutein with 2% H2SO4 in acetone, in addition to anhydrolutein I (54%) and 2',3'-anhydrolutein II (19%), also gave (3'R)-3'-hydroxy-3,4-dehydro-beta-carotene (3',4'-anhydrolutein III, 19%). While anhydrolutein I has been shown to be usually accompanied by minute quantities of 2',3'-anhydrolutein II (ca. 7-10%) in human plasma, 3',4'-anhydrolutein III has not been detected. The presence of anhydrolutein I and II in human plasma is postulated to be due to acid catalyzed dehydration of the dietary lutein as it passes through the stomach. These anhydroluteins have also been prepared by conversion of lutein diacetate to the corresponding anhydrolutein acetates followed by alkaline hydrolysis. However, under identical acidic conditions, loss of acetic acid from lutein diacetate proceeded at a much slower rate than dehydration of lutein. The structures of the synthetic anhydroluteins, including their absolute configuration at C(3) and C(6') have been unambiguously established by 1H NMR and in part by 13C NMR, and circular dichroism.

Chromatography, High Pressure Liquid↗
PubMed1995

Structure elucidation of the algal carotenoid (3S,5R,6R,3'S,5'R,6'S)-13'-cis-7',8'-dihydroneoxanthin-20'-AL 3'-beta-lactoside (P457). Part 2, Nmr studies.

Extensive nmr studies on the algal carotenoid P457 [1], its octaacetate 2, and a heptaacetate 3 resulted in the elucidation of its structure including the C-13'-cis configuration of the cross-conjugated C-20'-al chromophore, the relative stereochemistry of the allenic end group, the presence of an uncommon C-7',C-8'-single bond, the C-5',C-6'-epoxide, and of a beta-lactoside attached to C-3' of the carotenoid. P457 [1] is one of the most structurally complex carotenoids known, and its 1H- and 13C-nmr data have been fully interpreted.

Animals↗
PubMed1993

All-alpha-D-linked tetra- and penta-saccharide substructures of Trestatin A by block syntheses with triflic anhydride as promoter.

The perbenzylated maltosyl and maltotriosyl fluorides 6 and 16 were treated with 2,3,2',3',6'-penta-O-benzyl-4,6-O-benzylidene-alpha,alpha-trehalose (7) using triflic anhydride as a promoter to give all-alpha-D-linked tetra- and penta-saccharides which were finally deblocked to the free oligosaccharides 4-O-alpha-maltosyl-9 and 4-O-alpha-maltotriosyl-alpha,alpha-trehaloses 18. The 1H NMR spectra of some of the compounds were fully analyzed by 1D TOCSY and ROESY experiments.

Anhydrides↗
PubMed1992

Isolation and structural elucidation of the geometrical isomers of lutein and zeaxanthin in extracts from human plasma.

All-E-(3R,3'R,6'R)-lutein, all-E-(3R,3'R)-zeaxanthin, all-E-(3R,3'S,6'R)-3'-epilutein and some geometrical isomers of the former two dihydroxycarotenoids have been separated from an extract of human plasma by semipreparative high-performance liquid chromatography on a silica-based nitrile-bonded column. In the order of chromatographic elution, the isolated fractions were identified as all-E-lutein, all-E-zeaxanthin, all-E-3'-epilutein, 9Z-lutein, 9'Z-lutein, a mixture of 13Z-lutein and 13'Z-lutein, 9Z-zeaxanthin, 13Z-zeaxanthin and 15Z-zeaxanthin. The structures of all compounds, including the relative configuration at C(3') and C(6') of the luteins and the position of the stereomutated double bonds in the geometrical isomers, were unambiguously established by 1H nuclear magnetic resonance spectroscopy. The absolute configuration of the three all-E compounds was derived by circular dichroism and is also assumed to be valid for the geometrical isomers. The ultraviolet-visible absorption and mass spectra of each of the individually isolated compounds were also in agreement with the proposed structures.

Carotenoids↗
PubMed1991

Carotenoids of Erwinia herbicola and an Escherichia coli HB101 strain carrying the Erwinia herbicola carotenoid gene cluster.

Carotenoid pigments of Erwinia herbicola and a transformed strain of Escherichia coli carrying the carotenoid biosynthesis gene cluster of E. herbicola have been analyzed. Both organisms are capable of making essentially the same carotenoids, indicating that all of the genes required for the biosynthesis of the wild type E. herbicola carotenoids have been transformed intact into E. coli. The major products in both species of bacteria are beta-cryptoxanthin glucoside, zeaxanthin monoglucoside and zeaxanthin diglucoside. These compounds are the first example of secondary, non-allylic carotenoid glucosides. The absolute configuration 3R,3'R for zeaxanthin diglucoside was determined from its circular dichroism spectrum. Both species of bacteria also accumulate small amounts of hydrocarbon carotenes with similar cis/trans isomerization states.

Carotenoids↗
PubMed1978

Carotenoids of rhizobia. II. The effect of nicotine on the carotenoid pattern of Rhizobium lupini.

With increasing concentrations in the growth medium of the cyclization inhibitors nicotine or 2-(4-chlorophenylthio)-triethylamine hydrochloride (CPTA) the previously identified bicyclic carotenoids of Rhizobium lupini (2,3,2',3'-tetrahydroxy-beta,beta-caroten-4-one and 2,3,2',3'-tetrahydroxy-beta,beta-carotene) were successively replaced by hitherto unknown monocyclic carotenoids. By application of mass and nuclear magnetic resonance spectroscopy 3 carotenoids were identified as 2,3-trans-dihydroxy-beta,psi-caroten-4-one, 2,3-trans-dihydroxy-beta,psi-carotene, and 3-hydroxy-beta,psi-caroten-4-one. A further compound was tentatively established as (2- or 3-)monohydroxy-beta,psi-carotene. It was found that other inhibitors such as diphenylamine or 4-chloro-5-(dimethylamino)-2-alpha,alpha,alpha(trifluoro-m-tolyl)-3-(2H)-pyridazinone (San 6706) did not affect the pigment pattern. The results are discussed in relation to carotenoid biosynthesis in Rhizobium lupini.

Carotenoids↗