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Biomedical subjects

P E Cleaton-Jones

Publications and source records attributed to P E Cleaton-Jones.

At least 19 recordsLinked to original sources
PubMed1992

Plaque quantitation through protein measurement.

This study was undertaken to establish whether the quantitation of dental plaque protein by a dye-binding method (Coomassie G-250) may be used as an index of the amount of dental plaque sampled. Ten sites were sampled in 34 children on 5 occasions at 4 month intervals. The mean protein concentration in 1391 plaque samples was 6.9 +/- 4.1 micrograms (micrograms) (mean +/- standard deviation). A three-way analysis of variance showed that the plaque protein concentration was similar at the different sampling sites in the same child (p = 0.14), but statistically significant differences were observed with respect to time of sampling (F = 36.24; p = 0.0001) and individual sampled (F = 5.69; p = 0.0001). These observations indicate that plaque bacterial counts may be expressed as units of protein concentration and this method may be useful to relate the number of viable bacteria to an estimate of the amount of plaque collected. This ratio allows standardisation for any variation in the amount of plaque collected.

Analysis of Variance↗
PubMed1991

The effects of ion implantation on the beaks of orthodontic pliers.

The surface of stainless steel may be hardened by bombarding the material with a stream of nitrogen ions generated by a nuclear accelerator. In the present study this technique was used to determine the hardening effect of ion implantation on the beaks of stainless steel orthodontic pliers. Ten orthodontic pliers (Dentarum 003 094) were divided into two equal groups, designated control and experimental. The beaks of the experimental pliers were subjected to ion implantation, after which the tips of the beaks of all the pliers were stressed in an apparatus attached to an Instron testing machine. A cyclical load of 500 N was applied to the handles of the pliers, while a 0.9 mm (0.036 inch) round, stainless steel wire was held between the tips of the beaks. The effect of the stress was assessed by measurement with a traveling microscope of the gap produced between the tips of the beaks. Measurements were taken before loading and after 20, 40, 60, and 80 cycles. Statistical analysis of variance and the two-sample t tests indicated that there was a significant increase in the size of the gap as the pliers were stressed from 0 to 80 cycles (p less than 0.001). Furthermore, the mean gap was significantly greater in the control group than in the experimental group (p less than 0.001). This study suggests that ion implantation increases the hardness of the tips of the beaks of orthodontic pliers.

Analysis of Variance↗
PubMed1991

Temperature gradients in periodontal pockets.

This study was undertaken to determine whether there is any correlation of temperature within periodontal pockets with their depths. Pocket temperatures were measured with a thermocouple at 1 mm intervals of depth in 247 pockets, in 20 patients with periodontitis, mesiobucally and mesiopalatally/mesiolingually in relation to 6 standard teeth. Pocket temperatures increased consistently with pocket depth. Maxillary pockets were cooler than mandibular pockets, but in both jaws the differences between buccal and palatal/lingual pockets were not statistically significant. The findings are in keeping with knowledge about the increased temperature of inflamed tissues and the study appears to have relevance to the diagnosis of disease activity in pockets, but further studies are necessary to establish reference levels of pocket temperature.

Adult↗
PubMed1978

Intermittent exposure of gravid rats to 1% nitrous oxide and the effect on the postnatal growth of their offspring.

Three groups of pregnant rats were exposed to 1% nitrous oxide 6 hours a day, 5 days per week for the first, first and second, and all 3 weeks of gestation. The offspring were weighed and measured at weekly intervals. The following variables were evaluated in control and experimental groups: litter size, body weight, tail length and body length. Litter sizes in animals exposed for the first and second weeks of gestation were significantly smaller than the controls. A two-way nested statistical analysis of the data revealed that over an 8-week period the experimental rats were significantly smaller than the control rats of the same age. Analysis of the 95% confidence intervals revealed no particular pattern related to the timing of the exposure to nitrous oxide.

Animals↗
PubMed1978

Histologic response of replanted teeth pretreated with acidulated sodium fluoride.

Central incisors in the vervet monkey were extracted, endodontically treated, and replanted into their original sockets after immersion in a 2 per cent acidulated sodium fluoride solution (pH 5.5) for 30 minutes. Histologic examination at 1, 2, 4, and 8 weeks postoperatively showed that by the second week resorption had taken place and that ankylosis, first seen by the fourth week, along both the buccal and palatal root surfaces, was well established by the eighth week. Under the conditions of the study, pretreatment of the tooth roots with 2 per cent acidulated sodium fluoride did not reduce root resorption and ankylosis.

Acids↗
PubMed1978

Comparison of sampling techniques for studies of nitrous oxide pollution.

The retention of nitrous oxide in samples of nitrous oxide in air held in disposable plastic syringes, glass syringes and custom-made nylon film bags was studied by means of gas chromatography at intervals of 90 min, 24, 48 and 120 h after filling the containers. After 24 h the nylon bags retained a mean concentration of 94.5% of the original concentration of nitrous oxide. The disposable plastic syringes and glass syringes were unsatisfactory and retained only 80% of the original concentration of nitrous oxide after 90 min. These values decreased to 51% and 31% of the original concentration of nitrous oxide respectively at 24 and 48 h.

Air Pollution↗
PubMed1978

Design and use of an inhalation chamber for air pollution studies in small animals.

Environmental chambers provide a convenient means of studying the toxicology of gases in experimental animals. The specialised equipment needed for these studies is not commercially available. This paper reports on the design, construction and performance of a simple, and inexpensive, inhalation chamber and gas mixing unit for air pollution studies in small laboratory animals. Provision has been made for controlling the mixing of gases, the ventilation rate, the even distribution of gases in the chamber and for the removal of vented gases to prevent the hazard of air pollution in the laboratory animal facility. No significant differences were found between the food and water consumption and body mass gain of a group of rats housed in the chamber for 5 days and a control group housed im similar cages located in a rodent room and managed under conventional laboratory conditions. The chamber fulfills all the requirements for an animal inhalation system.

Air Pollutants↗