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Biomedical subjects

B P Sullivan

Publications and source records attributed to B P Sullivan.

8 recordsLinked to original sources
PubMed2006

Surface plasmon resonance investigations of human epidermal growth factor receptor 2.

This investigation utilizes surface plasmon resonance (SPR) spectroscopy to detect and quantify human epidermal growth factor receptor 2 (HER-2), an oncogene product that is over-expressed in some aggressive forms of breast cancer. Specifically, the HER-2 trans-membrane protein p185 and its extra cellular fragment p105 are analytes targeted in this work by using a gold-based biosensor slide on which an anti-HER-2 antibody has been immobilized by attachment to Protein G that is fixed to the gold film. A detection limit of > or =11 ng/mL for p185 resulted when trastuzumab was used as the anti-HER-2 antibody on the biosensor slide. Experiments with semi-purified p105 revealed that it binds weakly and reversibly to trastuzumab, therefore complicating its detection and quantification. Results of studies that reacted a 13-amino-acid peptide (PP13) from the HER-2 kinase domain with its specific antibody were critically different than p185 and p105 studies. Spectral analysis of the reflectivity at constant bulk buffer refractive index revealed a progressive negative SPR shift over time. A negative shift suggests that a loss of protein mass from the anti-PP13 antibody-Protein G biosensor is occurring. Several possibilities that may explain these negative SPR shifts are discussed.

Antibodies, Monoclonal↗
PubMed2003

Electrocatalytic reduction of nitrate in water.

Nitrate (NO(3)(-)) contamination of groundwater is a common problem throughout intensive agricultural areas (nonpoint source pollution). Current processes (e.g., ion exchange, membrane separation) for NO(3)(-) removal have various disadvantages. The objective of this study was to evaluate an electrocatalytic reduction process to selectively remove NO(3)(-) from groundwater associated with small agricultural communities. A commercially available ELAT (E-Tek Inc., Natick, MA) carbon cloth with a 30% surface coated Rh (rhodium) (1microg x cm(-1)) was tested at an applied potential of -1.5 V versus standard calomel electrode (SCE) with a Pt auxiliary electrode. Electrocatalytic reduction process (electrolysis) of NO(3)(-) was tested with cyclic voltammetry (CV) in samples containing NO(3)(-) and 0.1M NaClO(4)(-). Nitrate and NO(2)(-) concentrations in test solutions and groundwater samples were analyzed by ion chromatography (IC). The presence of Rh on the carbon cloth surface resulted in current increase of 36% over uncoated carbon cloths. The electrocatalysis experiments using Rh coated carbon cloth resulted in reduction of NO(3)(-) and NO(2)(-) on a timescale of minutes. Nitrite is produced as a product, but is rapidly consumed upon further electrolysis. Field groundwater samples subjected to electrocatalysis experiments, without the addition of NaClO(4)(-) electrolyte, also exhibited removal of NO(3)(-) on a timescale of minutes. Overall, results suggest that at an applied potential of -1.5 V with respect to SCE, Rh coated carbon cloth can reduce NO(3)(-) concentrations in field groundwater samples from 73 to 39 mg/L (16.58 to 8.82 mg/L as N) on a timescale range of 40-60 min. The electrocatalytic reduction process described in this study may prove useful for removing NO(3)(-) and NO(2)(-) from groundwater associated with nonpoint source pollution.

Agriculture↗
PubMed2003

Gas-phase detection of trinitrotoluene utilizing a solid-phase antibody immobilized on a gold film by means of surface plasmon resonance spectroscopy.

A multilayered biosensor was constructed and found to detect trinitrotoluene (TNT) in ppb concentrations in air both prior to and after detonation of TNT without use of a liquid phosphate buffered saline (PBS) superstrate. The biosensor surface was fabricated from a monoclonal antibody for TNT covalently bound to an 11,11'-dithio-bis(succinimidoylundecanoate) (DSU) self-assembled monolayer immobilized on a thin gold film bonded to a BK7 glass slide. The binding between the immobilized antibody and TNT antigen was detected using surface plasmon resonance spectroscopy (SPRS). Biosensor specificity for TNT was demonstrated with chemical homologues as well as against an unrelated explosive, RDX.

Air Pollutants↗
PubMed1991

Acceleration of N-nitrosation reactions by electrophiles.

Selected mechanisms by which electrophiles can facilitate N-nitrosamine formation are reviewed. Special attention is given to a recently discovered reaction in which nitrogen in its lowest (ammonia) oxidation state is efficiently converted to N-nitroso compounds by oxidation in the presence of secondary amines; an electrophilic transition metal centre (E+) makes this reaction possible by initially N-coordinating the ammonia (E+ + NH3----E-NH3+). Other mechanisms considered include: the conversion of nitrite under nonacidic conditions via nitro complexes to nitrosatively active transition metal nitrosyl intermediates (E+ + NO(2-)----E-NO(2-)----E-NO2+); catalysis of N-nitrosamine formation in nitrite-amine mixtures by electrophilic carbon centres that initiate the reaction by attack on the amine (E+ + R2NH----E-NR2); and coordination of nitrite by carbon electrophiles to form activated O-bound species (E+ + ONO(-)----E-O-NO) capable of performing the required N-nitrosation. The findings suggest that acceleration of N-nitrosamine-forming reactions by electrophiles may be a critical factor to consider in attempting to rationalize, predict and control the distribution of carcinogenic N-nitroso compounds in vivo and in the environment.

Chemical Phenomena↗
PubMed1991

Threshold models applied to Holstein conformation traits.

Threshold animal models were applied to five conformation traits of Canadian Holsteins. The estimated breeding values for sires from the threshold model allowed the calculation of predicted percentages of daughters in the desirable categories. Results were compared with those from a linear animal model in terms of their ability to predict future percentages of daughters in the desirable categories using an independent set of data. There was no advantage in a threshold model compared with a conventional linear animal model in its ability to predict future daughter performance. This was likely due to the 18 categories used in the classification of major type traits in Canada and the nearly normal distribution of observations across categories.

Animals↗
PubMed1990

Use of Chenopodium hybridum facilitates isolation of brome mosaic virus RNA recombinants.

Three mutant brome mosaic virus (BMV) RNA-2 transcripts bearing two alterations in the pseudoknot region and one in arm C of the 3' tRNA region, previously characterized as being deficient in tRNA-like functions, have been assayed for their ability to infect and replicate (in the presence of wild-type RNAs-1 and -3) in Chenopodium hybridum plants. Although the introduced mutations have been shown to incapacitate the replication of RNA-2 in barley protoplasts, C. hybridum plants inoculated with these mutants developed local lesions indistinguishable in appearance and morphology from control inoculations containing wild-type RNA-2. Sequence analysis of progeny RNA-2 from two single lesion isolates for each mutant inoculum revealed that the input mutations were restored to functional sequences by homologous recombination within the 3'tRNA-like region. These results, which reflect the ease with which progeny RNA can be characterized from single lesions, exemplify the value of C. hybridum for studying recombination among viral RNAs.

Base Sequence↗