Biomedical subjects

R Duguid

Publications and source records attributed to R Duguid.

15 recordsLinked to original sources

PubMed1989

Applications and admissions to UK dental schools through UCCA: 1968-1987.

Applications and admissions to UK dental schools through the UCCA system have been analysed for the 20-year period from 1968 to 1987. Applications rose from 1225 in 1968 to a peak of 3065 in 1974. By 1987, applications had fallen to 2050, 67% of the peak number. The ratio of male:female applicants has declined from 4:1 in 1968 to 1.6:1 in 1987. The number of dental students accepted through UCCA has varied much less during the 20-year period, rising from 831 in 1968 to a peak of 989 in 1980, and falling back to 893 in 1987. The number of dental students admitted to dental schools through UCCA in the 4 years including and after 1984 was 7.4% less than in the 4 years prior to 1984. This suggests that the 1984 cut of 10% was not fully achieved. The ratio of male:female students admitted has fallen from 3.4:1 in 1968 to 1.4:1 in 1987. In every year studied, the male:female ratio of UCCA applicants was higher than for accepted dental students. This could suggest that female applicants to dental school have higher academic or personal qualities than their male counterparts.

Educational Measurement↗

PubMed1987

The effect of arginine on in-vitro acid production by the oral bacterium Streptococcus mutans 10449 in various concentrations of glucose.

Acid production was measured both with constant pH and with the pH being allowed to fall. Under both conditions 10 mM arginine reduced it. There was also evidence that arginine reduced the rate of uptake of glucose by the bacterium. Thus arginine may affect the rate of glucose transport or catabolism by Strep. mutans 10449, and has more than a simple buffering effect on these cultures.

Acetates↗

PubMed1986

Measurements of ionic fluoride in milk.

Procedures used for measuring ionic fluoride in both human and cow's milk have been investigated. A number of factors were found to affect fluoride ion measurements in milk samples including time, stirring and the method of cleaning the fluoride electrode. Following these investigations a procedure was developed for estimating ionic fluoride in milk. Human milk collected from a fluoridated area (Newcastle-upon-Tyne) was found to contain significantly more ionic fluoride (0.065 ppm) than human milk from mothers in a non-fluoridated area (Dundee, 0.035 ppm).

Animals↗

PubMed1985

In-vitro acid production by the oral bacterium Streptococcus mutans 10449 in various concentrations of glucose, fructose and sucrose.

At intermediate and high concentrations, the results with the sugars were similar, with lactic acid as the main end product. Over 4 h, the pH fell from approx. 7 to 4. At low monosaccharide concentrations (2 mM glucose, 2 and 5 mM fructose), after an initial pH drop and period of lactic-acid production, evidence of pH rise and lactic-acid consumption were noted. This did not happen when sucrose was added to the bacteria. There was evidence of a heterolactic-acid fermentation pattern at low-sugar concentrations, lactic, acetic and formic acids being produced in similar amounts. The results suggest that, when low-sugar concentrations are present in dental plaque, Strep. mutans is capable of consuming previously-formed lactic acid.

Acetates↗

PubMed1985

Inhibition of [3H]-thymidine uptake in human gingival fibroblasts by extracts from human dental plaque, oral bacteria of the Streptococcus and Actinomyces species.

Extracts from human dental plaque, Streptococcus mutans, Streptococcus salivarius, Streptococcus faecalis, Streptococcus sanguis, Actinomyces israelli and Actinomyces odontolyticus inhibited [3H]-thymidine uptake by primary human gingival fibroblast cell lines as previous work has shown in respect of HeLa cells. The results show that a variety of oral bacteria, not usually considered to be periodontal pathogens, elaborate factors that adversely affect fibroblasts.

Actinomyces↗

PubMed1983

Acid phosphatase activity of human gingival fibroblasts measured using a simultaneous coupling semi-permeable membrane technique.

Acid phosphatase activity has been measured in cultured human gingival fibroblasts using a validated histochemical simultaneous coupling semi-permeable membrane technique. The histochemical reaction was linear over a three hour incubation period and had a pH optimum of 5.0. The activity was not increased by prior exposure to hypotonic acetate buffer and was inhibited by fluoride and molybdate but not by formaldehyde. These results indicate that the semi-permeable membrane technique described may be used for observing and measuring acid phosphatase activity in cultured fibroblasts. From results obtained using inhibitors, it appears that in these cells most of the acid phosphatase observed is lysosomal. The absence of any activation of activity following pre-incubation with hypotonic buffer indicates that the method is not suitable for monitoring lysosomal membrane function.

Acid Phosphatase↗

PubMed1983

Copper-inhibition of the growth of oral streptococci and actinomyces.

Copper ions were found to inhibit the rate of growth in broth culture of Streptococcus mitis, Streptococcus mutans, Streptococcus salivarious, Streptococcus sanguis, Actinomyces viscosus and Actinomyces naeslundii. In all cases, 10(-3) M copper inhibited the rate of growth, whereas 10(-4) M and lower concentrations had little or no effect. At the concentrations used in mouthwashes one mode of action of copper ions is to reduce the rate of growth of oral bacteria in vitro.

Actinomyces↗

PubMed1982

The effect of extracts from human dental plaque, oral streptococci and actinomyces bacteria on HELA cell growth, [3H]-thymidine uptake and 51Cr release.

Dialysed extracts from dental plaque and a number of species of oral streptococci and actinomycetes have been investigated for their effects on cell growth, [3H]-thymidine uptake and 51Cr release from HeLa cell cultures. Eight of the 15 extracts inhibited cell growth and all but one inhibited [3H]-thymidine incorporation. None of the extracts stimulated 51Cr release from prelabelled cells. These results suggest that many of the species of streptococci and actinomyces found in the mouth and in dental plaque are capable of producing high mol. wt substances that interfere with HeLa cell cultures by inhibiting [3H]-thymidine uptake and DNA synthesis but do not affect the degree of intactness of the external cell membrane.

Actinomyces↗

PubMed1982

Relationship between restorations and the level of the periodontal attachment.

Two hundred and forty stained extracted teeth with a restoration on one proximal surface and with no restoration on the opposite surface were investigated for the position and quality of the restoration and the position of the periodontal attachment. Only 27% of restorations were of good quality, 60% had overhangs and 13% deficiencies. The mean difference in loss of periodontal attachment (LOA) between the two surfaces for all teeth was 0.36 mm when the distance from the cemento-enamel junction to the periodontal membrane on the unrestored surfaces was subtracted from that on the restored surfaces. If allowance is made for those restorations located apical to the cemento-enamel junction, the LOA difference was 0.18 mm.

Dental Restoration, Permanent↗

PubMed1982