Biomedical subjects
Publications and source records attributed to M Andrews.
The PAR index and Summers' Occlusal Index have both been used to assess orthodontic treatment standards. The validity and reliability of these two indices is compared when applied to a group of 80 study models. The more recently developed PAR index was found to be as reliable and as valid as Summers' Occlusal Index.
The outcome of orthodontic treatment is reported for a sample of 220 patients treated by Norwegian specialist orthodontists. The outcome was assessed using objective measures. The indices can be used to identify differences not only between individual practitioners, but also health care systems. It can be confirmed that the Norwegian orthodontists are producing a high standard of orthodontic treatment, the malocclusion is on average reduced by 78 per cent.
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Training and calibration in use of the PAR Index was given to a number of clerical staff and dental advisers at the Dental Practice Board of England and Wales. The results show that it is possible to teach nondentally trained personnel to apply this index to a high degree of reliability and they could, therefore, be trained to measure occlusal changes produced by orthodontic treatment, both for third party payment agencies, and for internal or regional audit programmes. Application of indices by non-dental staff would not only be more economical on clinical time, but should augment the objectivity and impartiality of the index.
A systematic sample of 1010 cases was collected by the Dental Practice Board. The commonest type of treatment involved extraction of the first premolars followed by removable appliances. Treatment duration was on average 1.9 years, one-arch fixed appliances were started in an older age group and two-arch fixed appliance treatment took longer to complete than other appliance types. The best standard of treatment was achieved using upper and lower fixed appliances.
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The PAR Index has been developed to provide a single summary score for all the occlusal anomalies which may be found in a malocclusion. The score provides an estimate of how far a case deviates from normal alignment and occlusion. The difference in scores between the pre- and post-treatment cases reflects the degree of improvement and, therefore, the success of treatment. Excellent reliability was exhibited within and between examiners (Intraclass Correlation Coefficient, R greater than 0.91). The components of the PAR Index have been weighted to reflect current British orthodontic opinion and is flexible in that the weightings could be changed to reflect future standards and standards currently being achieved in other countries. The PAR Index offers uniformity and standardization in assessing the outcome of orthodontic treatment.
In orthodontics it is important to objectively assess whether a worthwhile improvement has been achieved in terms of overall alignment and occlusion for an individual patient or the greater proportion of a practitioner's caseload. An objective measure is described that has been validated against the subjective opinions of 74 dentists. Using the weighted PAR Index it was revealed that at least a 30 per cent reduction in PAR score is required for a case to be considered as 'improved' and a change of 22 PAR points to bring about 'great improvement'. For a practitioner to demonstrate high standards the proportion of an individual's case load falling in the 'worse or no different' category should be negligible and the mean reduction should be as high as possible (e.g. greater than 70 per cent). If the mean percentage reduction in PAR score is high and the proportion of cases that have been 'greatly improved' is also high, this indicates that the practitioner is treating a great proportion of cases with a clear need for treatment to a high standard.
Cholesterol sulfate is a component of several biological membranes. In erythrocytes, cholesterol sulfate inhibits hypotonic hemolysis, while in sperm, it can decrease fertilization efficiency. We have found cholesterol sulfate to be a potent inhibitor of Sendai virus fusion to both human erythrocyte and liposomal membranes. Cholesterol sulfate also raises the bilayer to hexagonal phase transition temperature of dielaidoyl phosphatidylethanolamine as demonstrated by differential scanning calorimetry and 31P nuclear magnetic resonance spectrometry. Although hexagonal phase structures are not readily found in biological membranes, there is a correlation between the effects of membrane additives on bilayer/non-bilayer equilibria and membrane stabilization. It is proposed that the ability of cholesterol sulfate to alter the physical properties of membranes contributes to its stabilization of biological membranes and the inhibition of membrane fusion.
New York state enacted the first safety belt use law in the United States in 1984. We evaluated the effects of the law by reviewing all hospital admissions from motor vehicle crashes in Monroe County, New York. We compared admissions for the 18 months prior to the effective date of the law with those for the 18 months after the law became effective. Police accident reports and hospital records were coupled and intensively reviewed. Motorcyclists, pedestrians, and bicyclists (bicycle collisions with motor vehicles) became controls for the study. Seat belt usage was determined from police and hospital record information. Analysis of the data revealed that safety belt use among patients hospitalized because of motor vehicle accidents increased from 11.2% before the law became effective to 53% after the law became effective. Hospital admissions decreased 11.9% among motor vehicle occupants and increased 2.6% among controls. The ISS decreased from 16.01 to 14.55 for motor vehicle occupants and increased from 14.77 to 15.11 among controls. Among subjects all injuries decreased except injuries of the spine and abdomen, which increased in the postlaw period.
Azobenzene (AZB) is non-carcinogenic in mice, but a potent rat carcinogen, inducing tumours in the spleen and other abdominal organs. The present paper shows that AZB clearly induces micronuclei in the bone marrow of rats at a dose of 375 mg/kg and above. In mice, however, only a marginally positive response was seen at much higher doses, thus reflecting the species-specific carcinogenic effect of the compound. The clastogenic effect of a single dose of AZB was not detectable in the rat 24 h after dosing, but at the 48 h sampling time and later. However, when a multiple-dosing regimen was used, an accumulation of micronucleated polychromatic erythrocytes (PEs) was seen and the effect was detected 24 h after the last dose. Micronucleus induction in rats was paralleled by increased methaemoglobin levels followed by anaemia. This resulted in accelerated erythropoiesis, as indicated by both the increased percentage of PEs in bone marrow and the increased reticulocyte count in peripheral blood. In mice, anaemia and methaemoglobaemia were seen. However, there was no compensatory increase in the percentage of PEs or any consistent change in the reticulocyte count. Stimulation of erythropoiesis could therefore be a contributory factor in the micronucleus induction by AZB seen in rats. One of the major metabolites of AZB, aniline, was also found to cause micronucleus induction in rats. Aniline is also a rat-specific carcinogen. It may therefore be speculated that AZB acts as a carcinogen via the formation of aniline, which might then be metabolized in different ways in rats and mice.
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Thirty-six cases of Wegener's granulomatosis (WG) and microscopic polyarteritis (MPA) presenting to the nephrology service in Leicester between 1980 and 1989 were reviewed. Apart from the diagnostic respiratory tract lesions seen in WG, cases of MPA and WG could not be distinguished by age and sex, range and severity of organ involvement, response to treatment (oral prednisolone and cyclophosphamide), mortality or renal outcome. The combined incidence of WG and MPA in 1980-86 was 1.5/million/year. Following the introduction in January 1987 of an assay for anti-neutrophil cytoplasmic antibody (ANCA), the incidence of WG and MPA increased in 1987-89 to 6.1/million/year (p less than 0.0001). Cases seen during these two periods did not differ by any clinical parameter except that later cases had less severe renal disease at referral and improved renal outcome. Median serum creatinine was significantly lower at presentation in 1987-89 (p less than 0.02). Of those surviving 3 months from presentation only 1/20 in 1987-89 had end stage renal failure compared with 4/10 in 1980-86 (p less than 0.02). These findings may reflect increasing diagnostic awareness of WG and MPA among physicians since the introduction of ANCA.
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The duration of exposure to ultrasound was measured in 1274 patients having a routine examination during their first visit to an antenatal clinic. The measured median exposure time was 105 s. Since pulsed ultrasound was used (duty cycle of 1 in 800) the actual median maternal exposure time was 131 ms. Exposure of the fetus would usually be less since it rarely occupies the full width of the image. The relevance of exposure time to the safety of diagnostic ultrasound and the implications for users and manufacturers are discussed.
In guinea-pigs intravenously infused with digoxin, prior immunization using a digoxin-human serum albumin conjugate increased by 3- and 2.4-fold, respectively, the digoxin doses causing the first signs of cardiotoxicity and death. At death, serum digoxin concentration was four times higher in immunized than in control animals. In the immunized guinea-pigs 50% of the serum digoxin was protein bound, presumably mainly to digoxin-specific antibodies, since in the controls the bound fraction was only 1-2%. Generally, tissue digoxin concentrations were not increased to the same extent as the lethal dose, and in the heart and lungs the increase was not significant. With cardiac (ventricle) subcellular fractions, there was no difference between control and immunized animals in the digoxin concentration of the 'microsomal' pellet. This subfraction contains the plasma membrane and the associated sodium pumps which are considered to be the sites at which the pharmacologically active digoxin binds. It seems likely, therefore, that the greater digoxin resistance in the immunized animals can be explained on the basis of reduced drug access to the site of action within the heart.