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Biomedical subjects

J Middleton

Publications and source records attributed to J Middleton.

At least 73 records · Page 4Linked to original sources
PubMed1993

Comparison of assessments made by a consultant in public health and housing staff on applications for rehousing on medical grounds.

This paper describes a review of a new system introduced in October 1989 for rehousing on medical grounds, in which housing staff were primarily responsible for making both the assessment and the decision. Part of this review included a study to compare points awarded by housing staff with those awarded by a consultant in public health. Major discrepancies were found in 11.6 per cent of decisions, of which only half were considered potentially to disadvantage applicants. On the basis of this review, it was felt that there was justification in using non-medical personnel to make decisions on medical priority, with medical officers acting in an advisory capacity only. The mechanism for processing applications, however, needs careful consideration, as does the overall role of medical priority in the allocation of housing.

Adolescent↗
PubMed1993

Ventral spinal cord inhibition of neurite outgrowth from embryonic rat dorsal root ganglia.

Organotypic culture of embryonic rat lumbar spinal cord and dorsal root ganglia has been used to demonstrate an inhibitory effect of ventral spinal cord on neurite growth from dorsal root ganglion explants. When dorsal root ganglion explants from 14-15 day old embryos were cultured alone or in close proximity to a dorsal cord explant, the pattern of dorsal root ganglion neurite outgrowth was typically radial. However, when E14-15 dorsal root ganglion explants were cocultured for 22-24 hours in proximity to a ventral spinal cord explant from the same embryo, few, if any, dorsal root ganglion neurites grew in the direction of the ventral cord explant. This inhibitory effect appeared to be developmentally regulated; it was diminished or absent in cocultures prepared from 18 day old embryos. In contrast, in cocultures of dorsal cord and ventral cord explants from E14-15 embryos, dorsal cord neurites grew abundantly toward the ventral cord explant suggesting that the inhibition is not likely to be due to a nonspecific neurotoxic effect and that the activity responsible selectively inhibits dorsal root ganglion neurite outgrowth. We conclude that a diffusible, primary afferent inhibitory factor(s) produced by embryonic ventral horn may be responsible for the inhibition. Our results are discussed with respect to the possible involvement of inhibition in the normal development of primary afferent innervation of the spinal cord.

Animals↗
PubMed1992

Stresses induced by edgewise appliances in the periodontal ligament--a finite element study.

The quantification of stress in the periodontal ligament is an important concept, as stress in this tissue is transmitted to the alveolus, with subsequent bone remodelling and tooth movement. A number of clinical studies have suggested figures for such an optimal stress range. This study makes use of a finite element technique to determine the stress induced in the periodontal ligament in three dimensions when a maxillary canine tooth is subjected to an orthodontic force similar to that produced by an edgewise appliance. The maximum stress induced at the cervical margin of the periodontal ligament was 0.072 N/mm2, while the maximum stress induced at the level of the apical foramen was 0.0038 N/mm2. These results are discussed in the light of known clinical experience and compared with the stresses produced in the periodontal ligament by other orthodontic forces. The findings would suggest that even with 'perfect' edgewise mechanics it would be difficult to obtain canine movement by pure translation or 'bodily movement.'

Alveolar Process↗
PubMed1991

The pattern and timing of cutaneous hair follicle innervation in the rat pup and human fetus.

The postnatal development of hair follicle innervation was studied in the rat hindlimb using a silver stain which detects large and medium calibre cutaneous nerve fibres. The pattern and timing of innervation in relation to postnatal changes in follicle growth were studied providing new data on nerve-target interactions in the developing peripheral nervous system. Sensory axons begin to leave the dermal plexus and grow towards follicles at P (postnatal day) 3 but do not start to innervate them until P7 or achieve an adult appearance until P19. The first terminals are circumferential, followed some days later by the appearance of palisade endings. The number of axons innervating a hair follicle increases steadily with age until P19 and there is no evidence of exuberant innervation of follicles during development. Hair follicle density in the rat is maintained during development due to waves of small, vellus follicle growth later in postnatal life as the skin grows. The percentage of follicles innervated however, decreases from the second postnatal week onwards presumably because late developing vellus hairs do not become innervated. Comparative analysis in human fetal abdominal skin using the same silver stain reveals a similar sequence and pattern of innervation to the rat over the period of 22 to 35 weeks EGA (estimated gestational age). Human skin does not, however, undergo the late waves of follicle growth seen in the rat. Follicular density decreases and the percentage of innervated follicles increases in the third trimester of fetal life.

Animals↗
PubMed1991

An outbreak of Legionnaires' disease in Gloucester.

Fourteen people living in or near the city of Gloucester fell ill with Legionnaires' disease caused by Legionella pneumophila serogroup (SG) 1 between 27 August and 27 October 1986. Another patient had fallen ill on 30 May. Nine of the 15 were diagnosed retrospectively during a case finding exercise. There were three deaths. Three cases of Pontiac fever were also diagnosed. The source was probably one or more wet cooling towers. Nineteen premises in the city with such towers were identified, and three just outside Gluocester. Samples from 11 of the 22 premises grew Legionella spp.; from nine of these L. pneumophila SG 1 (Pontiac) was isolated. The efficacy of regular addition of biocide in addition to hypochlorite added at the time of disinfection in inhibiting the growth of Legionella spp. was demonstrated. A survey of patients' movements during their likely incubation period showed that there was no single building that all patients had visited, but there were two areas of the city which nearly all had visited or passed through by car. A case-control study demonstrated an association with one of these areas. Cooling towers near both areas may have been sources but the evidence is insufficient to incriminate any single one. The unexpected finding of L. pneumophila SG 1 (Pontiac) in nine towers supports the hypothesis that there may have been multiple sources. Cooling towers may have been contaminated by mains water or by drift from other towers.

Adult↗
PubMed1991

A stress analysis of the periodontal ligament under various orthodontic loadings.

The accurate modelling of teeth under orthodontic load in the laboratory has many shortcomings in that it has not been possible to integrate methods, such as three-dimensional models, photo-elastic stress analysis, laser holographic interferometry, and animal studies, to give comprehensive and repeatable results. In this study, using a three-dimensional finite element model of a human maxillary canine tooth, the maximum principal stresses in the periodontal ligament produced by various orthodontic forces were determined. 1 Newton tipping forces produced stresses at the cervical margin of the periodontal ligament as high as 0.196 N/mm2 and apical stresses up to -0.034 N/mm2, while rotatory forces of two equal, but opposing forces of 0.5 Newton at the cervical margin of the crown produced cervical margin stresses ranging between -0.035 and 0.051 N/mm2, and apical stresses of between 0.0018 and 0.0027 N/mm2. These stresses are examined and discussed in relation to previous clinical, laboratory, and histological studies.

Computer Simulation↗
PubMed1991

A finite element study of canine retraction with a palatal spring.

The use of a removable appliance to retract a maxillary canine tooth into a first premolar extraction space is one of the most commonly performed orthodontic procedures. However, unwanted movements may occur, including excessive tipping, rotation, and flaring of the tooth. The present investigation by the use of a finite element model quantifies some of the initial stresses produced within the periodontal ligament when two obliquely directed forces are applied to a maxillary canine tooth. In simulating the action of a removable appliance it attempts to relate the stress patterns to the nature of the subsequent tooth movement.

Cuspid↗
PubMed1990

Three-dimensional analysis of orthodontic tooth movement.

A three-dimensional finite element model was used to investigate the biomechanical response of an upper canine tooth. The physical model was developed from ceramic replicas and X-rays, and consisted of cancellous and cortical bone, the periodontal ligament, dentine and pulp chamber. Horizontal forces were applied at the tip of the crown and at the cervical margin and a rotational force was applied at the cervical margin of the tooth crown. The resulting displacements and stress field for each load case are presented with particular emphasis being placed on the response of the periodontal ligament. The investigation shows that quantitative information on initial tooth movement can be accurately predicted and used to evaluate the response of orthodontic treatment.

Biomechanical Phenomena↗
PubMed1989

Thinking about head injuries in children.

The number of head injuries in children is rising annually and the number is by no means insignificant. Although the relatively small number of severe injuries has been acknowledged to produce profound and long-term effects, the majority of injuries are comparatively mild. In the past, mild injuries have not been thought to produce significant cognitive or psychological sequelae. This view is now being challenged, suggesting that professionals need be aware of the subtle sequelae that can effect children's functioning in the home and classroom. Children, once seen as having an advantage over adults with regard to their recovery, may in fact be more vulnerable and have poorer prognoses. Adequate rehabilitation provision for the unique complexity of problems following head injury is rarely met by Health and Education Authorities. Children with head injuries are neither sick nor mentally handicapped, and they need a rehabilitation service that fits their special needs. Finally, little within the literature of children's head injury has been written on children's own experience of their predicament. One notable exception is the work of McCabe and Green (1987). Children are often acutely aware of their difficulties once they begin to recover, mourning the loss of past skills and abilities, and the loss of freedoms they once had. Yet they are only partially able to understand how their world is so different. Frustration, fear, anger and sorrow are not uncommon feelings expressed either verbally or through their behaviour. In thinking about head injury in children it is their experience of this trauma that must be foremost in our minds.

Age Factors↗
PubMed1989

Should performance indicators in general practice relate to whole practices or to individual doctors?

In a study of referrals to East Anglian hospitals 737 referrals in six specialties from three general practices were examined to see how accurately the hospital computer master index had identified the referring practice, the referring general practitioner and the doctor with whom the patient was registered. Although the practice was accurately identified by the hospital computer in 97% of referrals, the identification of the referring doctor and the patient's registered general practitioner were less reliable (72% and 49% respectively). It is concluded that at present the practice rather than the individual doctor may be the appropriate unit of analysis for studies of general practitioners' referral rates. This may be true for other performance indicators where information on a doctor's case mix and workload is not available. The results of this study emphasize that problems may arise if data relating to individual general practitioners are interpreted out of context of the practice and the way in which it is organized.

England↗
PubMed1989

A city aims to rid itself of drink-driving.

The city of Coventry in the United Kingdom aims to be free of drink-driving by the year 2000. The recommendations of a seminar held to consider this goal are presented below.

Adolescent↗