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Biomedical subjects

B A Goodman

Publications and source records attributed to B A Goodman.

At least 19 recordsLinked to original sources
PubMed2003

Free radicals in wheat flour change during storage in air and are influenced by the presence of ozone during the growing season.

Electron paramagnetic resonance (EPR) spectra of wheat flour show components from Fe(III), Mn(II) and free radicals (FR). The metal signals were higher in the samples from the stressed plants, and reflected the higher total levels of these elements determined analytically. They remained essentially constant throughout the experiment, but the FR signal increased progressively with time over a period of 4-6 months after milling, after which it reached a maximum. The rate of increase in the FR signal during this period was considerably higher in the flour from plants that had been exposed to elevated ozone levels.

Electron Spin Resonance Spectroscopy↗
PubMed2002

Infection of leaves of Arabidopsis thaliana by Botrytis cinerea: changes in ascorbic acid, free radicals and lipid peroxidation products.

Infection of leaves of Arabidopsis thaliana with conidial suspensions of the necrotrophic pathogen Botrytis cinerea resulted in a large decrease in the level of ascorbic acid and increases in intensity of a single-peak free radical and Fe(III) (g=4.27) signals in electron paramagnetic resonance (EPR) spectra. These changes were not confined to the spreading lesions or associated areas of chlorosis, but extended to other apparently healthy tissues in the infected leaves. They are, therefore, consistent with the existence of high levels of oxidative stress being generated as a result of the infection process. The expected accompanying increases in levels of the aldehydic products of lipid peroxidation, malondialdehyde (MDA) and 4-hydroxy-2-nonenal (4-HNE), were not observed, and in the case of MDA the levels in tissue from infected plants were appreciably lower than in the healthy controls. These last findings are surprising and demonstrate a difference in the response of A. thaliana to infection with B. cinerea compared with tissues from other plant families studied previously.

Aldehydes↗
PubMed2001

Botrytis cinerea induces the formation of free radicals in fruits of Capsicum annuum at positions remote from the site of infection.

Free radical adducts of the spin trap alpha-(4-pyridyl-1-oxide)-N-tert-butylnitrone have been observed by electron paramagnetic resonance spectroscopy in detached fruits of Capsicum annuum investigated 5 days after infection with Botrytis cinerea. The spectra of these adducts were at a maximum within the soft rot lesion, but they could also be detected at distances up to 50 mm from the edge of the lesion in samples following main vascular bundles. At distances greater than 40 mm, the spectrum of the ascorbate radical was also seen, and at greater distances from the lesion it was the only radical detected. With samples taken from parenchyma tissue adjacent to the vascular bundles there was little adduct formation and the ascorbate radical could be detected, albeit with reduced intensity compared to healthy tissue, at distances as small as 10 mm from the edge of the lesion. This observation of chemical changes at considerable distances from the infected tissue is in contrast to previous observations on the behaviour of other markers of oxidative stress (e.g., 4-hydroxynonenal, malondialdehyde, single-peak free radical, and Fe(III) (g = 4.27) electron paramagnetic resonance signals), where their levels decreased rapidly outside of the soft rot.

Botrytis↗
PubMed2001

Markers for oxidative stress associated with soft rots in French beans (Phaseolus vulgaris) infected by Botrytis cinerea.

The role of active oxygen species has been studied in spreading soft-rot lesions caused by the necrotrophic fungal pathogen Botrytis cinerea Pers.:Fr. in leaves of four genotypes of French bean (Phaseolus vulgaris L.). Large increases were observed for the aldehydic end-products of oxidative damage, malondialdehyde and 4-hydroxy-2-nonenal, as a result of infection in each of the genotypes studied. Similar increases were found in a stable free radical and g=4.27 Fe(III) signals, but not Mn(II) signals, in electron paramagnetic resonance spectra. These changes were accompanied by large decreases in ascorbic acid levels, with changes in the antioxidant glutathione being genotype dependent.

Aldehydes↗
PubMed2001

Stable free radicals in ozone-damaged wheat leaves.

Chlorophyll fluorescence measurements were performed on attached leaves of wheat plants (Triticum aestivum L. cv. Nandu) that were exposed to ambient air and to air supplemented with 80 and 120 nmol mol-1 ozone. Decreases in the "current photochemical capacity" were observed that were dependent on both the ozone concentration and duration of exposure. Electron paramagnetic resonance (EPR) spectra on freeze-dried samples from the same batches of plants showed the presence of an unidentified stable free radical, whose spectra had similarities to that of the ubisemiquinone radical. The intensity of this radical signal increased with the duration of ozone exposure in leaves that received an additional 120 nmol mol-1 ozone. In contrast, with exposure to air with 80 nmol mol-1 added ozone, there was little if any change in free radical signal intensity over the 4 week period of the experiment. The increase in intensity of the EPR signal occurred later than the chlorophyll fluorescence changes, which suggests that it is associated with permanent leaf damage.

Chlorophyll↗
PubMed2000

Synthesis of alpha-substituted beta-amino acids using pseudoephedrine as a chiral auxiliary.

[reaction: see text] beta-Amino acids are becoming increasingly attractive as intermediates in the synthesis of a variety of molecular structures. However, few methods are available for the synthesis of alpha-substituted beta-amino acids that are both readily scalable and highly stereoselective. Herein we report a new method for synthesizing alpha-substituted beta-amino acids that satisfies both of these requirements using enantiomerically pure pseudoephedrine as a chiral auxiliary.

Amino Acids↗
PubMed1997

Non-destructive visualisation in three dimensions of freezing events in flowers of blackcurrant (Ribes nigrum L.) using spin-echo NMR microscopy.

Flowers of blackcurrant (Ribes nigrum L.) were subjected to freezing stress in vivo, and the resulting damage examined in three dimensions using a spin-echo nuclear magnetic resonance imaging sequence. Increased signal intensity was detected in the damaged flowers, particularly at the base of the style, in T2-weighted images. This is thought to be the result of intracellular freezing, which causes membrane damage and leakage of cellular contents. It is proposed that this represents the main site of damage within the flowers. The imaging of flowers of differing developmental ages showed larger increases in signal from fully open flowers after freezing damage compared with those in the initial stages of bud, suggesting that the enclosed nature of the flower buds may have a protective effect on the sensitive stylar base. The use of three-dimensional nuclear magnetic resonance imaging provides a rapid and effective means for the visualisation of freezing events within floral tissues; the effective resolution of the images enables greater accuracy and clarity in interpretation than hitherto possible in two dimensions.

Freezing↗
PubMed1996

High field NMR microscopic imaging of cultivated strawberry fruit.

The experimental conditions required for discrimination of various types of tissue in fruits of cultivated strawberry (Fragaria x Ananassa) at high fields (ca. 7 T) have been investigated. In marked contrast to soft fruits of other species, from which informative images have been derived at high fields using a variety of pulse sequences and acquisition parameters, appreciable image intensities from parenchymal and vascular tissues in healthy strawberry fruits were obtained only with a spin-echo imaging sequence using large sweep widths (ca. 100,000 Hz), and consequently small values for TE ( < 5 ms), indicating predominantly short T2 values for these tissues. Damage caused by infection by the fungal pathogen Botrytis cinerea is readily seen as a result of a large increase in T2 in the infected tissue, whereas ripening processes appear to be characterized primarily by small variations in the T2-weighted contrast and in the relative magnitudes of T1 between vascular and parenchymal tissue. In addition, it was possible selectively to enhance the contributions to images from the achenes ("seeds") by using very short relaxation delays, thereby enhancing T1-dominated contrast mechanisms.

Fruit↗
PubMed1995

Evaluation of the allergic/irritant potential of air pollutants: detection of proteins modified by volatile organic compounds from oilseed rape (Brassica napus ssp. oleifera) using electrospray ionization-mass spectrometry.

BACKGROUND: Upward trends in allergy and asthma rates have been reported in most western societies, including the UK, where around 15-20% of the population now suffer from allergy or asthma. Scientific proof of the causes of these increases relies on accurate assessment of exposure and standardized diagnostic tests, such as for specific IgE in blood serum and skin testing. For many air pollutants it has proven difficult to assess an individual's exposure outside an occupational environment and reliable test development is hampered by not knowing whether an allergic or irritant mechanism is involved. These problems are particularly evident in the controversial issue of whether airborne releases from oilseed rape can cause health effects. OBJECTIVE: To develop a method for evaluating the allergic/irritant potential of air pollutants and to assess whether the volatile organic compounds emitted by oilseed rape have this potential. METHODS: Proteins were exposed in vitro to volatile organic compounds emitted by oilseed rape. Electrospray ionization-mass spectrometry was used to detect any resultant protein modifications. RESULTS: Dimethyl disulphide, thiocyanic acid methyl ester and 2-methyl-propanenitrile were able to modify human proteins. In addition, two isothiocyanates which can be emitted by damaged oilseed rape also have this ability. The major products emitted by undamaged oilseed rape, terpenes, a sesquiterpene and a terpene alcohol did not have this property, but the possible role of their oxidized products is discussed. CONCLUSION: Some of the volatile organic compounds emitted by oilseed rape have the potential to be allergens/irritants. Standardized modified proteins produced by this method should prove useful for biomonitoring human exposure in molecular epidemiological studies as well as in diagnostic tests. This method should find further application in investigations into the possible health effects of other environmental pollutants.

Air Pollutants↗
PubMed1995

The use of quantified maximum entropy methods for optimising information from electron paramagnetic resonance spectroscopy.

A quantified maximum entropy method is applied to the optimisation of analytical information from EPR spectra of free radicals. Statistically meaningful errors are produced for the positions and intensities of all spectral peaks and considerable improvements in sensitivity compared with conventional spectral enhancement procedures are obtained with measurements of the intensities of spectra of known radicals.

Algorithms↗
PubMed1993

A mobile element on a virus particle surface identified by nuclear magnetic resonance spectroscopy.

The presence of a mobile element in the coat protein of pepper ringspot tobravirus (PRV) has been established by 1H n.m.r. spectroscopy; two-dimensional correlation spectroscopy (COSY) measurements show that this element consists of alanine, asparagine, glycine, proline, serine and threonine only. By reference to the amino acid sequence of the coat protein, it is concluded that the mobile element is associated with the C-terminal region and consists of between 11 and 38 residues.

Amino Acid Sequence↗
PubMed1993

Developments in the understanding of the particle structure of tobraviruses.

Particles of tobraviruses resemble those of tobacco mosaic tobramovirus (TMV) in having helical symmetry and in being rod-shaped. However, isolated tobravirus coat protein and TMV coat protein respond to changes in the ionic strength and pH of the solute in contrasting ways. The types of aggregate formed in solutions of coat protein also differ which may be related to differences in the apparent mechanism of reconstitution of virus particles from isolated protein and RNA. The amino acid sequences of tobravirus and tobramovirus coat proteins have been shown to be similar in some regions known to be important for the structure of TMV particles. These alignments also show that tobravirus proteins are larger than tobramoviral proteins in part because of extra residues at the C-terminus. Tobravirus particles give a signal in proton NMR spectroscopy but TMV particles do not. The signal is caused by segmental mobility of the C-terminal peptide. This difference between TMV and tobraviruses may be related to a property not shared by tobraviruses and TMV and it is therefore speculated that the mobile C-terminal peptide of tobravirus coat proteins may be important in the transmission of tobravirus particles by nematode vectors.

Amino Acid Sequence↗
PubMed1990

Spin trapping of free radicals and lipid peroxidation in microsomal preparations from malignant hyperthermia susceptible pigs.

Microsomes were prepared from livers of malignant hyperthermia susceptible (MHS) or resistant (MHR) pigs. On incubation with the spin trap alpha-(4-pyridyl-l-oxide)-N-tert-butylnitrone (4-POBN), the microsomes from MHS pigs produced a characteristic electron spin resonance (ESR) signal at a greater rate than those from MHR pigs. Increased formation in the incubations of thiobarbituric acid reactive substances (TBARS) by the microsomes of the MHS pigs indicated an enhanced susceptibility to free radical-mediated lipid peroxidation. These results provide further evidence that MHS pigs have an antioxidant abnormality which may contribute to the fatal MH response. However the nature of the abnormality is unclear. The enhanced formation of unstable free radicals and indices of lipid peroxidation was not due to decreased vitamin E concentration or glutathione peroxidase activity in the microsomes. Furthermore, fatty acid profiles were similar in microsomes from MHS and MHR pigs indicating similar amounts of potential substrate for TBARS formation.

Animals↗
PubMed1989

An electron spin resonance investigation of internal rust spot, a physiological disorder of the potato tuber.

ESR spectroscopy has been used to investigate the formation of paramagnetic species during the development of internal rust spot (IRS) in the potato tuber. Production of free radicals and oxidation of metal ions such as Fe(II) and Mn(II) occur when necrotic tissue is formed. However, since IRS develops in periods of calcium stress (low calcium supply), it is suggested that the principal cause of the disorder is a loss of cell membrane integrity which is brought about by a lack of calcium. Cell senescence and the formation of necrotic tissue may then result either from increased oxygen radical production within the cell or from oxidation of metal complexes in the extracellular regions of the tissue.

Electron Spin Resonance Spectroscopy↗