Biomedical subjects

G M Steele

Publications and source records attributed to G M Steele.

6 recordsLinked to original sources

PubMed1999

Assessment of the antioxidant potential of scotch whiskeys by electron spin resonance spectroscopy: relationship to hydroxyl-containing aromatic components.

Electron spin resonance (ESR) spectroscopy has been used to assess the antioxidant capacity of eight Scotch whiskeys by measuring the extent by which the original spirits, or pyridine solutions of their residues, reduced Fremy's radical or galvinoxyl radical. All whiskeys displayed antioxidant activity greater than that of a 0.2 mM solution of Trolox in the Fremy's assay and of a 0.1 mM solution of quercetin in the galvinoxyl assay. The relative antioxidant capacities determined according to the two assays were highly correlated and strongly related to the total phenol content as determined by using the Folin-Ciocalteu method. Activity was a consequence of maturation in oak casks with the "newmake" spirit showing no effect. Of 10 aromatic constituents analyzed, activity was most strongly correlated with ellagic acid and gallic acid in both assays. The reductive capacities of four major phenolics were determined, which, in summation, accounted for 31-53% of the total antioxidant activity of the whiskeys. There was no evidence for synergistic interaction between the phenols investigated.

Alcoholic Beverages↗

PubMed1998

The effect of whisky and wine consumption on total phenol content and antioxidant capacity of plasma from healthy volunteers.

OBJECTIVE: To assess whether consumption of 100 ml of whisky or red wine by healthy male subjects increased plasma total phenol content and antioxidant capacity. DESIGN: A Latin square arrangement to eliminate ordering effects whereby, after an overnight fast, nine volunteers consumed 100 ml of red wine, malt whisky or unmatured 'new make' spirit. Each volunteer participated on three occasions one week apart, consuming one of the beverages each time. Blood samples were obtained from the anticubital vein at intervals up to 4h after consumption of the beverages when a urine sample was also obtained. RESULTS: Within 30 min of consumption of the wine and whisky, there was a similar and significant increase in plasma total phenol content and antioxidant capacity as determined by the ferric reducing capacity of plasma (FRAP). No changes were observed following consumption of 'new make' spirit. CONCLUSIONS: Consumption of phenolic-containing alcoholic beverages transiently raises total phenol concentration and enhances the antioxidant capacity of plasma. This is compatible with suggestions that moderate alcohol usage and increased antioxidant intake decrease the risk of coronary heart disease.

Adult↗

PubMed1991

Dissemination, replication, and trans-stadial persistence of Dugbe virus (Nairovirus, Bunyaviridae) in the tick vector Amblyomma variegatum.

The dissemination and replication of Dugbe (DUG) virus and its tissue tropisms in the tick vector Amblyomma variegatum were examined by immunohistochemical analysis using specific antibody, in situ hybridization with a viral-complementary riboprobe, and infectivity assays of dissected tissues. Dugbe virus was localized in both unfed and feeding adults inoculated as nymphs or orally infected by capillary feeding, and in nymphs infected by capillary feeding. In non-feeding ticks, the main sites of DUG virus replication were the epidermis, hemocytes associated with loose connective tissue, and a small number of phagocytic digestive cells in the gut lumen. Virus infectivity in the hemolymph was associated entirely with hemocytes. Dugbe viral antigen or infectivity was not detected in the salivary glands until after the start of feeding. Viral titers in the salivary glands of feeding ticks were about ten-fold higher than in gut, ovary, or loose connective tissue. The level of infection decreased during molting and increased during feeding. Viral particles and pathologic effects were not detected in infected ticks. The primary site of trans-stadial persistence of DUG virus is the hemocytes. Tick hemocytes and other motile cells may be important in the transmission of persistent virus infection from one cell or organ to another by diapedesis.

Animals↗

PubMed1989

Difference in vector competence of two species of sympatric ticks, Amblyomma variegatum and Rhipicephalus appendiculatus, for Dugbe virus (Nairovirus, Bunyaviridae).

Amblyomma variegatum was shown to be a competent vector of Dugbe (DUG) virus whereas Rhipicephalus appendiculatus was not. When DUG virus was taken up orally by A. variegatum nymphs, during capillary feeding, the virus replicated and persisted through moulting to the following adult stage. In contrast, although DUG virus replicated in capillary fed R. appendiculatus nymphs, the virus did not persist trans-stadially into the adult stage. If the oral route of infection was by-passed by direct inoculation into the haemocoel, DUG virus replicated and survived trans-stadially in both tick species, and was subsequently transmitted during feeding. The different responses of R. appendiculatus to oral and intra-coelomic routes suggest that DUG virus is able to infect the gut of this tick species, but that release of the virus from the gut is inhibited.

Animals↗

PubMed1987

A novel mode of arbovirus transmission involving a nonviremic host.

In nature, infected and uninfected arthropod vectors often feed together on an animal. In mimicking this scenario in the laboratory, uninfected vectors were found to acquire virus while cofeeding on the same host as infected vectors. However, the vertebrate host on which they fed did not develop detectable levels of virus in its blood. These observations were made with Thogoto virus, an influenza-like virus of medical and veterinary significance. Rhipicephalus appendiculatus ticks were used as the vector and guinea pigs as the vertebrate host. The results demonstrate that a vertebrate that is apparently refractory to infection by an arthropod-borne virus can still play an important role in the epidemiology of the virus, and they suggest a novel mode of arthropod-borne virus transmission.

Animals↗

PubMed1981

Input and distractor modality effects upon the release from proactive interference in children.

Build-up of proactive interference (PI) with visual-picture and auditory-verbal input modalities and the subsequent release from Pi following a change in modality was investigated in three experiments with boys and girls, as follows: Experiment I (n=64) at two mean age levels, 7-6 and 10-5; Experiment II (n=64) at mean age 7-6; and Experiment III (n=48) at age 11-4. PI build-up occurred in both modalities for all ages tested. Release from PI occurred following a change from auditory to visual input by not from PI occurred following a change from auditory shift. In the final experiment, this asymmetrical improvement in performance was dependent upon an interaction between the modality of the input and distractor task on the final or release trial; changing to visual input produced a release effect regardless of the distractor task modality, while auditory input was associated with improvement in recall if a visual distractor task was employed whether or not a shift in input modality had occurred. This improvement was hypothesized to represent a decrease in retroactive interference rather than a release from proactive interference.

Child↗