Biomedical subjects
Publications and source records attributed to M L Hunter.
A case is described in which a complex odontome, associated with an unerupted and displaced mandibular permanent molar, presented as an acute infection of an edentulous area. Surgical removal of the odontome led to the spontaneous eruption of the tooth.
The aim of this study was to investigate changes in the condition of first permanent molars over the teenage years, with special reference to adolescents who lost premolar teeth for orthodontic purposes. A total of 453 South Wales schoolchildren (219 males and 234 females) were examined at the ages of 11-12 and 19-20 years. At 11-12 years, 89.6 per cent of the cohort had all four first permanent molars, while 3.3 per cent had already lost these teeth. Of those first permanent molars present, 61.7 per cent had some caries experience. At age 19-20, 80.6 per cent of subjects retained four first permanent molars while 4.4 per cent had none. Of the first permanent molars present, 80.6 per cent had been affected by caries. In 60 per cent of the 186 subjects (75 males and 111 females) who had lost premolar teeth in the course of orthodontic treatment, a sound premolar was extracted in preference to a first permanent molar which already had evidence of dental disease. At age 19-20 years, the majority of the first permanent molars were restored and otherwise sound, though a small number which had been restored at age 11-12 years had been lost due to caries.
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This study examines, from photographic records, the prevalence of accidental damage to maxillary incisor teeth in a group of 968 11/12-year-old South Wales school-children; 15.3% showed evidence of trauma ranging from enamel fractures or discolouration to actual loss of a tooth. Boys (19.4%) showed a higher prevalence of trauma than girls (11%). Maxillary central incisors were the most at risk from trauma, with coronal fractures being the most commonly sustained injury. Those subjects who showed evidence of trauma had an statistically (p less than 0.001) but not clinically significantly greater overjet than did those who had none. The percentage of subjects suffering trauma increased significantly with increasing overjet, but lip incompetence did not affect the prevalence of accidental damage. Though statistically unsupported due to the small numbers involved in this cohort, it appeared that the rougher nature of boys activities and their more active participation in sports were of greater importance than the magnitude of their overjet in determining whether their teeth were at risk from trauma. In contrast, it was the magnitude of the overjet which was the dominant factor in girls. Despite the wide availability of relatively simple means of restoration and, in the majority of cases, regular dental examinations, only 14.8% of traumatised teeth had received treatment at this age.
Reported toothbrushing frequency and the effect of toothbrushing frequency, toothbrushing hand, sex and social class on the incidence of plaque and periodontal disease in a group of 720 adolescents examined at age 11-12 years and again at 15-16 years is presented. At 11-12 years, the mean toothbrushing frequency was 11.5 times per week. By age 15-16 years, it had risen to 13.3 times per week. Children from social class I were less likely to brush once per day or less and more likely to brush twice daily than those from social class V. At both examinations, consistently low negative correlations were seen between reported toothbrushing frequency and the mean scores for buccal and lingual plaque, buccal, mesial and total bleeding. Few significant differences were seen between left- and right-handed toothbrushers at age 11-12 years. These were almost entirely due to differences between the boys. By age 15-16 years, no significant differences existed between the two groups. At both examinations, the boys had higher plaque, bleeding and pocketing scores than did the girls. At 15-16 years of age, all social classes exhibited lower mean total pocketing scores than at age 11-12 years. At 11-12 years of age, the social class differences were mainly contributed by the girls, while at re-examination plaque and bleeding scores for both sexes showed an overall trend to increase from social class I through to social class V. At 11-12 years of age, the boys showed a trend for pocketing to increase from social class I through to social class V. This was absent at 15-16 years of age. The girls showed no such trend at 11-12, but it had emerged by age 15-16. The results again demonstrate the influence of social class and sex rather than toothbrushing frequency and handedness on oral hygiene and gingival health. However, in view of the high number of statistical tests employed, some caution must be exercised in the interpretation of differences significant at the 5 per cent level.
The authors report a case of a young patient with conical midline supernumerary teeth. In cases where such supernumeraries are likely to erupt, early surgical intervention, often necessitating the administration of a general anaesthetic, should be avoided if possible. Extraction under local anaesthesia on eruption was preferred for this patient, and resulted in the normal eruption of the permanent central incisors.
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The optimum cofactor requirements for triacylglycerol biosynthesis in rat adipose-tissue homogenates containing mitochondrial, microsomal and cytosolic fractions were investigated. In general the optimum concentrations of cofactors for triacylglycerol biosynthesis were found to differ from those for total fatty acid esterification. The results provided further evidence for the key role of phosphatidate phosphohydrolase in the regulation of triacylglycerol biosynthesis. Albumin was included in the incubation medium to permit the use of concentrations of added fatty acids that would swamp the effects of endogenous fatty acids. The addition of albumin had little effect on the incorporation of palmitic acid and stearic acid into lipids including triacylglycerols. By contrast, a critical concentration of albumin (about 60 muM) was required before incorporation of oleic acid or linoleic acid into triacylglycerols occurred. The system was used to study the incorporation of different 1-14C-labelled fatty acids from a mixture of unesterified fatty acids [palmitic acid 30%; stearic acid 10%; oleic acid 40%; linoleic acid 20% (molar percentages)] separately into the positions 1,2 and 3 of triacyl-sn-glycerols. In general the stereo-specific distribution of the labelled fatty acids incorporated into triacylglycerols paralleled the normal distribution of fatty acids within rat adipose-tissue triacylglycerols, suggesting that the specificities of the relevant acyltrasferases have the major role in determining the positional distribution of fatty acids within triacylglycerols.
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Fatty acid components of cholesteryl esters from the adrenals of sheep, like those of nonruminants, were characterized by significant amounts of the longer chain metabolites of linoleic acid. Administration to sheep of diets rich in linoleic acid and protected against biohydrogenation did not alter the concentration of these components significantly. Although 18:2 levels were elevated, this was largely at the expense of cis-monoenoic fatty acids.
1. Linseed oil was incorporated gradually into the diet of four sheep until the animals received 90 g additional fat/d. Attempts were made to measure changes in concentration of substances and rates of synthesis in the rumen directly, and by incubation of rumen contents in vitro (zero-time technique). 2. The high-fat diet increased the dilution rate and the volume of rumen contents and decreased the synthesis of diaminopimelic acid in the rumen. The number of protozoa decreased and the number of bacteria increased in the rumen of animals receiving the high-fat diet. 3. The concentration of volatile fatty acids (VFA) in the rumen decreased for sheep given the high-fat diet, but the capacity of rumen contents to produce VFA in vitro increased. 4. The incorporation of radioactivity from [14C]acetate into lipids during incubation of rumen contents vitro increased with the amount of linseed oil in the diet. The greatest proportional increase was with the bacterial fraction of rumen contents. 5. In the group of four animals used, one animal showed consistent differences in the magnitude of the measured varibles. This animal appeared to have a smaller rumen, a lower dilution rate and larger concentrations of some substances in the rumen. A higher proportion of fatty acids appeared to be synthsized by the micro-organisms from this animal.