ram abuknesha - Academia.edu (original) (raw)

Papers by ram abuknesha

Uveitis occurs in a proportion of patients with ankylosing spondylitis, and an increased faecal i... more Uveitis occurs in a proportion of patients with ankylosing spondylitis, and an increased faecal isolation of the Gram-negative microorganism Klebsiella pneumoniae has been reported from such patients. Immunological cross-reactivity between K. pneumoniae and bovine vitreous humour has been studied by 2 different antibody binding techniques: 1251-labelled antigen binding assay with and without carrier, and beta-galactosidase enzyme-immunoassay. Sera from rabbits immunised with whole klebsiella microorganisms or klebsiella extracts were found to bind labelled vitreous humour antigens to a greater extent (p < 001) than sera from rabbits immunised with Escherichia coli, Streptococcus pyogenes, and OX 174 virus or sera from the same rabbits before immunisation. It is suggested klebsiella microorganisms may carry antigenic determinants which resemble vitreous humour antigens. In patients suffering from ankylosing spondylitis (AS) acute anterior uveitis (AAU) is a frequent peripheral complication, occurring in approximately 20 to 30% of cases.1 The Gram-negative microorganism Klebsiella pneumoniae has been isolated more frequently from faecal cultures of AS patients during active phases of the disease than during inactive phases, and the presence of uveitis was considered to be a good indicator of disease activity.2 K. pneumoniae was isolated in 13 out of 17 episodes (76 %) in AS patients with uveitis, compared with an overall klebsiella isolation rate of 30 % in AS patients without uveitis.3 Similar results have been reported by Eastmond and coworkers,4 though another group could not confirm these observations.5 Over 90% of AS patients carry the HLA-B27 antigen, while it is present in only 8 % of a Caucasian population.-8 In idiopathic acute anterior uveitis over 50% of patients carry HLA-B27,9 but, when AS occurs together with AAU, Geraint James found in a survey of 50 patients that the frequency of the B27 antigen rises to 98 %.10 It would appear that HLA B27 provides a genetic link between AS and uveitis. Since klebsiella microorganisms can not only be isolated from patients having AS and AAU, but also show cross-reactivity with some HLA B27 lymphocytes,"' it is possible that the

Journal of the American Society of Nephrology, 2002

ABSTRACT. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein wit... more ABSTRACT. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein with a unique structure and a molecular weight of ≈460 kD. The purpose of this study is to investigate the binding of the cystein-flanked leucine-rich repeats (LRR) of polycystin-1 to extracellular matrix (ECM) components. These interactions may play a role in normal renal development as well as the pathogenesis of autosomal-dominant polycystic kidney disease (ADPKD). In vitro assays were used to assess the binding of a fusion protein containing the LRR of polycystin-1 and that of affinity purified polycystin-1 to a number of ECM components. The results showed that the LRR modulate the binding of polycystin-1 to collagen I, fibronectin, laminin, and cyst fluid–derived laminin fragments. The addition of the LRR fusion protein to cells in culture resulted in a significant dose-dependant reduction in the rate of proliferation. Cyst fluid–derived laminin fragments had a stimulatory effect on ce...

Analytical Chemistry, 2000

... Hans-Martin Haake, † Leonie de Best, ‡ Hubertus Irth,* ‡ Ram Abuknesha, § and Andreas Brecht ... more ... Hans-Martin Haake, † Leonie de Best, ‡ Hubertus Irth,* ‡ Ram Abuknesha, § and Andreas Brecht #. Institute of Physical Chemistry, University of Tübingen, Auf der Morgnestelle 8, 72076 Tübingen, Germany, Division of Analytical ...

Biosensors and Bioelectronics, 1997

Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked ... more Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked immunosorbent assays. Transparent aminosilanized indium tin oxide coated glass electrodes were derivatized with aminodextran covalently modified with atrazine caproic acid. The labelled antibodies were used to investigate the derivatized electrodes colorimetrically and the electrodes were use in an electrochemiluminescence flow injection analyser. Electrochemiluminescence immunoassay for atrazine in the range 0-10 ppb showed that it was possible to detect less than 0.1 ppb, the precautionary limit for pesticides in drinking water recommended by the European Commission.

Analytica Chimica Acta, 2001

... This work is part of the European Union project RIANA (RIver ANAlyzer) that includes the deve... more ... This work is part of the European Union project RIANA (RIver ANAlyzer) that includes the development of a prototype with an optical immunosensor for the determination of atrazine, simazine, isoproturon, 2,4-D, alachlor and paraquat in river water samples. ...

Analytica Chimica Acta, 1998

Analytica Chimica Acta, 1997

We assessed a new sensing device based on the monitoring of immunobinding reactions using wavegui... more We assessed a new sensing device based on the monitoring of immunobinding reactions using waveguide surface plasmon resonance (WSPR) for the determination of simazine in water samples. Standard solutions between 0.1 and 1.0 μg l −1 analysed in triplicate showed a ...

Analytica Chimica Acta, 1995

Comparative trials were carried out on triazine microtiter plate tests distributed by Millipore, ... more Comparative trials were carried out on triazine microtiter plate tests distributed by Millipore, Riedel-de Haen, Transia and CIFEC. Sensitivity and reproducibility were tested with standard solutions of atrazine. Cross-reactivity was studied for hydroxyatrazine, deisopropylatrazine, deethylatrazine, simazine, hydroxysimazine, terbutylazine, hydroxyterbutylazine and deetylterbutylazine. A set of 19 surface-, 16 ground-and 6 lysimetric plate water samples were also analysed. Liquid chromatography with diode array detection or gas chromatography with nitrogen-phosphorus detection were used as validated control techniques for those natural samples. Laboratory assays developed by GEC-Marconi as part of a collaborative European Union research project (BIORTICAS) have also been assessed. The lowest detectable dose were those of Riedel and Transia tests, 0.003 and 0.014 pg/l, respectively. The other tests also enable the detection of atraxine below 0.1 pg/l. All tests showed inter-assay coefficients of variation (C.V.) below 20%, the Transia, GEC-Marconi and Riedel tests producing the lowest inter-assay C.V.s. The mean intra-assay C.V.s were below 7% for all tests, the most homogeneous results being those of Transia and CIFEC. Except for the GEC-Marconi test which appeared very specific for atrazine, the most interfering triazines were terbutylazine, simazine and deethylatrazine. For the complete set of 41 water samples, the triazine concentrations measured by all the immunoassays and the sum of the triazines determined by gas chromatography-liquid chromatography were correlated at the 0.001 level, while for the water samples collected from lysimetric plates, the correlation coefficients were less significant, except for the Riedel test whose correlation coefficient remained significant at the 0.001 level. The laboratory-based assay from GEC-Marconi, still under development, showed promising characteristics with respect to sensitivity and specificity. The Riedel-de Ha& test gave the best overall results.

Analytica Chimica Acta, 2001

An optical immunosensor coupled to a FIA system was developed and applied to monitor isoproturon ... more An optical immunosensor coupled to a FIA system was developed and applied to monitor isoproturon in various types of water samples. The assay is based on a solid phase fluorescence immunoassay with immobilised analyte derivative and free, fluorescence labelled antiisoproturon antibodies. Cross-reactivities (CRs) of linuron, diuron and chlortoluron were carried out to assess the influence of structurally similar compounds on the response of the biosensor. The highest CR values were obtained for diuron, 93%, whilst chlortoluron and linuron showed values of 53 and 46%, respectively, at 0.1 g l −1 of cross-reactant. Detection limits of 0.01 and 0.14 g l −1 were achieved after the analysis of MilliQ and river water samples, respectively. The validation of the biosensor was carried out analyzing Aquacheck certified river samples which contain different amounts of phenylurea pesticides. This River Analyser (RIANA) prototype with an optical immunosensor can be applied for monitoring of isoproturon in natural river water samples. Individual assays are completed within 15 min including total regeneration of the transducer.

Abstract. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein wit... more Abstract. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein with a unique structure and a molecular weight of �460 kD. The purpose of this study is to investigate the binding of the cystein-flanked leucine-rich repeats (LRR) of polycystin-1 to extracellular matrix (ECM) components. These interactions may play a role in normal renal development as well as the pathogenesis of autosomal-dominant polycystic kidney disease (ADPKD). In vitro assays were used to assess the binding of a fusion protein containing the LRR of polycystin-1 and that of affinity purified polycystin-1 to a number of ECM components. The results showed that the LRR modulate the binding of polycystin-1 to collagen I, fibronectin, laminin, and cyst fluid–derived laminin fragments. The addition of the LRR fusion protein to cells in culture resulted in a significant dose-dependant reduction in the rate of proliferation. Cyst fluid–derived laminin fragments had a stimulatory effect on ce...

Sensors and Actuators B: Chemical, 1995

The effects of water-miscible organic solvents have been investigated with respect to the stabili... more The effects of water-miscible organic solvents have been investigated with respect to the stability of immobilized antibodies, binding of hapten and conjugation to immobilized antibodies, and marker enzyme stability and activity. Polyclonal antibodies against a coumarin derivative have been isolated from sheep. Lactase and peroxidase are used as hapten labels for competitive enzyme-linked immunosorbent assay (ELISA) and flow-injection immunoanalysis (FIIA). Examples for improvements of the sensitivity and elution efficiency by the application of solvent-water mixtures are presented.

Journal of Steroid Biochemistry

Second European Workshop on Optical Fibre Sensors, 2004

ChemInform, 2001

ABSTRACT The development and application of immunosensors for environmental monitoring has grown ... more ABSTRACT The development and application of immunosensors for environmental monitoring has grown steadily in recent years. In this review, immunosensors developed in the last few years are highlighted regarding their importance and practical contribution to environmental analysis with particular emphasis on monitoring of pesticide levels. Different transduction elements and mechanisms used for the detection of the physicochemical change(s) produced by the biological interaction are shown, as well as their application to the development of real-time measurement devices or systems. In addition, examples concerning the analysis of pesticides in natural water samples obtained using a recently developed optical immunosensor are given. Validation of immunosensor measurements with conventional chromatographic techniques is also reported. The immunosensor system detection mechanism is based on a solid-phase fluoroimmunoassay combined with an optical transducer chip chemically modified with an analyte derivative. Applications to the analysis of atrazine, simazine, paraquat, alachlor, 2,4-D and isoproturon in water are also reviewed.

The Biochemical journal, 1983

A method for the preparation of casein labelled with the 4-methylumbelliferyl fluorophore is desc... more A method for the preparation of casein labelled with the 4-methylumbelliferyl fluorophore is described, and the product was used as a fluorigenic macromolecular substrate for a sensitive assay of the activity of proteinases. Nanogram quantities of trypsin, chymotrypsin, elastase and cathepsin D can be detected, but the substrate is unaffected by cathepsin B.

Journal of Steroid Biochemistry, 1979

ABSTRACT Antiserum raised in a goat against 17β-oestradiol-6-(O-carboxyimethyl) oxime-bovine seru... more ABSTRACT Antiserum raised in a goat against 17β-oestradiol-6-(O-carboxyimethyl) oxime-bovine serum albumin was fractionated to give its respective IgG fractions. Oestradiol-17β specific antibodies were isolated and their IgG1 fraction fluorescently labelled with 4-methylumbelliferone-3-acetic acid. An immunofluorimetric assay for oestradiol-17β is described in which endogenous steroid competes with AH-Sepharose 4B-immobilised ocstradiol-17β-6-(O-carboxymethyl)oxime for these fluorescently labelled antibodies.

Teubner-Reihe UMWELT, 1998

Water Research, 2010

The quantification of pathogenic bacteria in an environmental or clinical sample commonly involve... more The quantification of pathogenic bacteria in an environmental or clinical sample commonly involves laboratory-based techniques and results are not obtained for 24-72 h after sampling. Enzymatic analysis of microbial activity in water and other environmental samples using fluorescent synthetic substrates are well-established and highly sensitive methods in addition to providing a measure of specificity towards indicative bacteria. The enzyme b-D-glucuronidase (GUD) is a specific marker for Escherichia coli and 4-methylumbelliferone-b-D-glucuronide (MUG) a sensitive substrate for determining the presence of E. coli in a sample. However, currently used procedures are laboratory-based and require bench-top fluorimeters for the measurement of fluorescence resulting from the enzymesubstrate reaction. Recent developments in electronic engineering have led to the miniaturisation of fluorescence detectors. We describe the use of a novel hand-held fluorimeter to directly analyse samples obtained from the River Thames for the presence of E. coli. The results obtained by the hand-held detector were compared with those obtained with an established fluorescent substrate assay and by quantifying microbial growth on a chromogenic medium. Both reference methods utilised filtration of water samples. The miniaturised fluorescence detector was used and incubation times reduced to 30 min making the detection system portable and rapid. The developed hand-held system reliably detected E. coli as low as 7 cfu/mL river water sample. Our study demonstrates that new handheld fluorescence measurement technology can be applied to the rapid and convenient detection of bacteria in environmental samples. This enables rapid monitoring to be carried out on-site. The technique described is generic and it may, therefore, be used in conjunction with different fluorescent substrates which allows the assessment of various target microorganisms in biological samples.

Uveitis occurs in a proportion of patients with ankylosing spondylitis, and an increased faecal i... more Uveitis occurs in a proportion of patients with ankylosing spondylitis, and an increased faecal isolation of the Gram-negative microorganism Klebsiella pneumoniae has been reported from such patients. Immunological cross-reactivity between K. pneumoniae and bovine vitreous humour has been studied by 2 different antibody binding techniques: 1251-labelled antigen binding assay with and without carrier, and beta-galactosidase enzyme-immunoassay. Sera from rabbits immunised with whole klebsiella microorganisms or klebsiella extracts were found to bind labelled vitreous humour antigens to a greater extent (p < 001) than sera from rabbits immunised with Escherichia coli, Streptococcus pyogenes, and OX 174 virus or sera from the same rabbits before immunisation. It is suggested klebsiella microorganisms may carry antigenic determinants which resemble vitreous humour antigens. In patients suffering from ankylosing spondylitis (AS) acute anterior uveitis (AAU) is a frequent peripheral complication, occurring in approximately 20 to 30% of cases.1 The Gram-negative microorganism Klebsiella pneumoniae has been isolated more frequently from faecal cultures of AS patients during active phases of the disease than during inactive phases, and the presence of uveitis was considered to be a good indicator of disease activity.2 K. pneumoniae was isolated in 13 out of 17 episodes (76 %) in AS patients with uveitis, compared with an overall klebsiella isolation rate of 30 % in AS patients without uveitis.3 Similar results have been reported by Eastmond and coworkers,4 though another group could not confirm these observations.5 Over 90% of AS patients carry the HLA-B27 antigen, while it is present in only 8 % of a Caucasian population.-8 In idiopathic acute anterior uveitis over 50% of patients carry HLA-B27,9 but, when AS occurs together with AAU, Geraint James found in a survey of 50 patients that the frequency of the B27 antigen rises to 98 %.10 It would appear that HLA B27 provides a genetic link between AS and uveitis. Since klebsiella microorganisms can not only be isolated from patients having AS and AAU, but also show cross-reactivity with some HLA B27 lymphocytes,"' it is possible that the

Journal of the American Society of Nephrology, 2002

ABSTRACT. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein wit... more ABSTRACT. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein with a unique structure and a molecular weight of ≈460 kD. The purpose of this study is to investigate the binding of the cystein-flanked leucine-rich repeats (LRR) of polycystin-1 to extracellular matrix (ECM) components. These interactions may play a role in normal renal development as well as the pathogenesis of autosomal-dominant polycystic kidney disease (ADPKD). In vitro assays were used to assess the binding of a fusion protein containing the LRR of polycystin-1 and that of affinity purified polycystin-1 to a number of ECM components. The results showed that the LRR modulate the binding of polycystin-1 to collagen I, fibronectin, laminin, and cyst fluid–derived laminin fragments. The addition of the LRR fusion protein to cells in culture resulted in a significant dose-dependant reduction in the rate of proliferation. Cyst fluid–derived laminin fragments had a stimulatory effect on ce...

Analytical Chemistry, 2000

... Hans-Martin Haake, † Leonie de Best, ‡ Hubertus Irth,* ‡ Ram Abuknesha, § and Andreas Brecht ... more ... Hans-Martin Haake, † Leonie de Best, ‡ Hubertus Irth,* ‡ Ram Abuknesha, § and Andreas Brecht #. Institute of Physical Chemistry, University of Tübingen, Auf der Morgnestelle 8, 72076 Tübingen, Germany, Division of Analytical ...

Biosensors and Bioelectronics, 1997

Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked ... more Antibodies to atrazine were labelled with glucose oxidase and used in colorimetric enzyme linked immunosorbent assays. Transparent aminosilanized indium tin oxide coated glass electrodes were derivatized with aminodextran covalently modified with atrazine caproic acid. The labelled antibodies were used to investigate the derivatized electrodes colorimetrically and the electrodes were use in an electrochemiluminescence flow injection analyser. Electrochemiluminescence immunoassay for atrazine in the range 0-10 ppb showed that it was possible to detect less than 0.1 ppb, the precautionary limit for pesticides in drinking water recommended by the European Commission.

Analytica Chimica Acta, 2001

... This work is part of the European Union project RIANA (RIver ANAlyzer) that includes the deve... more ... This work is part of the European Union project RIANA (RIver ANAlyzer) that includes the development of a prototype with an optical immunosensor for the determination of atrazine, simazine, isoproturon, 2,4-D, alachlor and paraquat in river water samples. ...

Analytica Chimica Acta, 1998

Analytica Chimica Acta, 1997

We assessed a new sensing device based on the monitoring of immunobinding reactions using wavegui... more We assessed a new sensing device based on the monitoring of immunobinding reactions using waveguide surface plasmon resonance (WSPR) for the determination of simazine in water samples. Standard solutions between 0.1 and 1.0 μg l −1 analysed in triplicate showed a ...

Analytica Chimica Acta, 1995

Comparative trials were carried out on triazine microtiter plate tests distributed by Millipore, ... more Comparative trials were carried out on triazine microtiter plate tests distributed by Millipore, Riedel-de Haen, Transia and CIFEC. Sensitivity and reproducibility were tested with standard solutions of atrazine. Cross-reactivity was studied for hydroxyatrazine, deisopropylatrazine, deethylatrazine, simazine, hydroxysimazine, terbutylazine, hydroxyterbutylazine and deetylterbutylazine. A set of 19 surface-, 16 ground-and 6 lysimetric plate water samples were also analysed. Liquid chromatography with diode array detection or gas chromatography with nitrogen-phosphorus detection were used as validated control techniques for those natural samples. Laboratory assays developed by GEC-Marconi as part of a collaborative European Union research project (BIORTICAS) have also been assessed. The lowest detectable dose were those of Riedel and Transia tests, 0.003 and 0.014 pg/l, respectively. The other tests also enable the detection of atraxine below 0.1 pg/l. All tests showed inter-assay coefficients of variation (C.V.) below 20%, the Transia, GEC-Marconi and Riedel tests producing the lowest inter-assay C.V.s. The mean intra-assay C.V.s were below 7% for all tests, the most homogeneous results being those of Transia and CIFEC. Except for the GEC-Marconi test which appeared very specific for atrazine, the most interfering triazines were terbutylazine, simazine and deethylatrazine. For the complete set of 41 water samples, the triazine concentrations measured by all the immunoassays and the sum of the triazines determined by gas chromatography-liquid chromatography were correlated at the 0.001 level, while for the water samples collected from lysimetric plates, the correlation coefficients were less significant, except for the Riedel test whose correlation coefficient remained significant at the 0.001 level. The laboratory-based assay from GEC-Marconi, still under development, showed promising characteristics with respect to sensitivity and specificity. The Riedel-de Ha& test gave the best overall results.

Analytica Chimica Acta, 2001

An optical immunosensor coupled to a FIA system was developed and applied to monitor isoproturon ... more An optical immunosensor coupled to a FIA system was developed and applied to monitor isoproturon in various types of water samples. The assay is based on a solid phase fluorescence immunoassay with immobilised analyte derivative and free, fluorescence labelled antiisoproturon antibodies. Cross-reactivities (CRs) of linuron, diuron and chlortoluron were carried out to assess the influence of structurally similar compounds on the response of the biosensor. The highest CR values were obtained for diuron, 93%, whilst chlortoluron and linuron showed values of 53 and 46%, respectively, at 0.1 g l −1 of cross-reactant. Detection limits of 0.01 and 0.14 g l −1 were achieved after the analysis of MilliQ and river water samples, respectively. The validation of the biosensor was carried out analyzing Aquacheck certified river samples which contain different amounts of phenylurea pesticides. This River Analyser (RIANA) prototype with an optical immunosensor can be applied for monitoring of isoproturon in natural river water samples. Individual assays are completed within 15 min including total regeneration of the transducer.

Abstract. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein wit... more Abstract. Polycystin-1, the product of the PKD1 gene, is a membrane-bound multidomain protein with a unique structure and a molecular weight of �460 kD. The purpose of this study is to investigate the binding of the cystein-flanked leucine-rich repeats (LRR) of polycystin-1 to extracellular matrix (ECM) components. These interactions may play a role in normal renal development as well as the pathogenesis of autosomal-dominant polycystic kidney disease (ADPKD). In vitro assays were used to assess the binding of a fusion protein containing the LRR of polycystin-1 and that of affinity purified polycystin-1 to a number of ECM components. The results showed that the LRR modulate the binding of polycystin-1 to collagen I, fibronectin, laminin, and cyst fluid–derived laminin fragments. The addition of the LRR fusion protein to cells in culture resulted in a significant dose-dependant reduction in the rate of proliferation. Cyst fluid–derived laminin fragments had a stimulatory effect on ce...

Sensors and Actuators B: Chemical, 1995

The effects of water-miscible organic solvents have been investigated with respect to the stabili... more The effects of water-miscible organic solvents have been investigated with respect to the stability of immobilized antibodies, binding of hapten and conjugation to immobilized antibodies, and marker enzyme stability and activity. Polyclonal antibodies against a coumarin derivative have been isolated from sheep. Lactase and peroxidase are used as hapten labels for competitive enzyme-linked immunosorbent assay (ELISA) and flow-injection immunoanalysis (FIIA). Examples for improvements of the sensitivity and elution efficiency by the application of solvent-water mixtures are presented.

Journal of Steroid Biochemistry

Second European Workshop on Optical Fibre Sensors, 2004

ChemInform, 2001

ABSTRACT The development and application of immunosensors for environmental monitoring has grown ... more ABSTRACT The development and application of immunosensors for environmental monitoring has grown steadily in recent years. In this review, immunosensors developed in the last few years are highlighted regarding their importance and practical contribution to environmental analysis with particular emphasis on monitoring of pesticide levels. Different transduction elements and mechanisms used for the detection of the physicochemical change(s) produced by the biological interaction are shown, as well as their application to the development of real-time measurement devices or systems. In addition, examples concerning the analysis of pesticides in natural water samples obtained using a recently developed optical immunosensor are given. Validation of immunosensor measurements with conventional chromatographic techniques is also reported. The immunosensor system detection mechanism is based on a solid-phase fluoroimmunoassay combined with an optical transducer chip chemically modified with an analyte derivative. Applications to the analysis of atrazine, simazine, paraquat, alachlor, 2,4-D and isoproturon in water are also reviewed.

The Biochemical journal, 1983

A method for the preparation of casein labelled with the 4-methylumbelliferyl fluorophore is desc... more A method for the preparation of casein labelled with the 4-methylumbelliferyl fluorophore is described, and the product was used as a fluorigenic macromolecular substrate for a sensitive assay of the activity of proteinases. Nanogram quantities of trypsin, chymotrypsin, elastase and cathepsin D can be detected, but the substrate is unaffected by cathepsin B.

Journal of Steroid Biochemistry, 1979

ABSTRACT Antiserum raised in a goat against 17β-oestradiol-6-(O-carboxyimethyl) oxime-bovine seru... more ABSTRACT Antiserum raised in a goat against 17β-oestradiol-6-(O-carboxyimethyl) oxime-bovine serum albumin was fractionated to give its respective IgG fractions. Oestradiol-17β specific antibodies were isolated and their IgG1 fraction fluorescently labelled with 4-methylumbelliferone-3-acetic acid. An immunofluorimetric assay for oestradiol-17β is described in which endogenous steroid competes with AH-Sepharose 4B-immobilised ocstradiol-17β-6-(O-carboxymethyl)oxime for these fluorescently labelled antibodies.

Teubner-Reihe UMWELT, 1998

Water Research, 2010

The quantification of pathogenic bacteria in an environmental or clinical sample commonly involve... more The quantification of pathogenic bacteria in an environmental or clinical sample commonly involves laboratory-based techniques and results are not obtained for 24-72 h after sampling. Enzymatic analysis of microbial activity in water and other environmental samples using fluorescent synthetic substrates are well-established and highly sensitive methods in addition to providing a measure of specificity towards indicative bacteria. The enzyme b-D-glucuronidase (GUD) is a specific marker for Escherichia coli and 4-methylumbelliferone-b-D-glucuronide (MUG) a sensitive substrate for determining the presence of E. coli in a sample. However, currently used procedures are laboratory-based and require bench-top fluorimeters for the measurement of fluorescence resulting from the enzymesubstrate reaction. Recent developments in electronic engineering have led to the miniaturisation of fluorescence detectors. We describe the use of a novel hand-held fluorimeter to directly analyse samples obtained from the River Thames for the presence of E. coli. The results obtained by the hand-held detector were compared with those obtained with an established fluorescent substrate assay and by quantifying microbial growth on a chromogenic medium. Both reference methods utilised filtration of water samples. The miniaturised fluorescence detector was used and incubation times reduced to 30 min making the detection system portable and rapid. The developed hand-held system reliably detected E. coli as low as 7 cfu/mL river water sample. Our study demonstrates that new handheld fluorescence measurement technology can be applied to the rapid and convenient detection of bacteria in environmental samples. This enables rapid monitoring to be carried out on-site. The technique described is generic and it may, therefore, be used in conjunction with different fluorescent substrates which allows the assessment of various target microorganisms in biological samples.