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Biomedical subjects

E Macdonald

Publications and source records attributed to E Macdonald.

At least 19 recordsLinked to original sources
PubMed2004

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine.

OBJECTIVE: The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine. METHOD: Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM). RESULTS: Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine. CONCLUSION: Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on enamel or dentine. It must be assumed that studies which reported adverse effects on enamel and or dentine of bleaches reflect not the bleach itself but the pH of the formulation used.

Beverages↗
PubMed2001

The General Medical Council's Performance Procedures: peer review of performance in the workplace.

The General Medical Council procedures to assess the performance of doctors who may be seriously deficient include peer review of the doctor's practice at the workplace and tests of competence and skills. Peer reviews are conducted by three trained assessors, two from the same speciality as the doctor being assessed, with one lay assessor. The doctor completes a portfolio to describe his/her training, experience, the circumstances of practice and self rate his/her competence and familiarity in dealing with the common problems of his/her own discipline. The assessment includes a review of the doctor's medical records; discussion of cases selected from these records; observation of consultations for clinicians, or of relevant activities in non-clinicians; a tour of the doctor's workplace; interviews with at least 12 third parties (five nominated by the doctor); and structured interviews with the doctor. The content and structure of the peer review are designed to assess the doctor against the standards defined in Good Medical Practice, as applied to the doctor's speciality. The assessment methods are based on validated instruments and gather 700-1000 judgements on each doctor. Early experience of the peer review visits has confirmed their feasibility and effectiveness.

Clinical Competence↗
PubMed2001

The assessment of poorly performing doctors: the development of the assessment programmes for the General Medical Council's Performance Procedures.

BACKGROUND: Modernization of medical regulation has included the introduction of the Professional Performance Procedures by the UK General Medical Council in 1995. The Council now has the power to assess any registered practitioner whose performance may be seriously deficient, thus calling registration (licensure) into question. Problems arising from ill health or conduct are dealt with under separate programmes. METHODS: This paper describes the development of the assessment programmes within the overall policy framework determined by the Council. Peer review of performance in the workplace (Phase 1) is followed by tests of competence (Phase 2) to reflect the relationship between clinical competence and performance. The theoretical and research basis for the approach are presented, and the relationship between the qualitative methods in Phase 1 and the quantitative methods in Phase 2 explored. CONCLUSIONS: The approach is feasible, has been implemented and has stood legal challenge. The assessors judge and report all the evidence they collect and may not select from it. All their judgements are included and the voice of the lay assessor is preserved. Taken together, the output from both phases forms an important basis for remediation and training should it be required.

Clinical Competence↗
PubMed1999

Developmental changes in nicotinic receptor mRNAs and responses to nicotine in the suprachiasmatic nucleus and other brain regions.

Our previous studies demonstrated that nicotine induces c-fos expression in the suprachiasmatic nucleus (SCN) of the rat during a narrow developmental window occurring in the perinatal period. We have extended these observations by showing that c-fos cannot be induced in the adult SCN by nicotine even during the subjective night, when phase shifts do occur. In contrast to the SCN, significant induction of c-fos and NGFI-A was observed in the medial habenula and paraventricular nucleus at all circadian times. In the fetal rat SCN we show that NGFI-A and junB are also induced by nicotine, but not c-jun. To investigate whether changes in nicotinic acetylcholine receptor (nAChR) expression in the SCN may underlie this change in sensitivity during the perinatal period, we examined nAChR mRNAs across this developmental period. By Northern analyses, alpha2, alpha3 and alpha4 subunit mRNAs are relatively abundant in the fetal SCN but decline substantially in the adult. alpha7 mRNA increases substantially while beta2 mRNA is relatively abundant throughout development. We also examine expression in the whole mouse brain beginning at embryonic day 11. Many mRNA sizes for nAChR subunits in both the rat and mouse are characterized here for the first time by Northern analyses and some show very large changes in expression across development. In particular, a small 1.4 kb alpha2-related mRNA is highly expressed during early development, perhaps indicating an important novel function for this subunit.

Acetylcholine↗
PubMed1999

Sevoflurane anesthesia in desert tortoises (Gopherus agassizii).

The effects of sevoflurane on anesthesia induction, recovery, ventricular pressures, heart rate, ventricular pH, blood gas values, and electrolytes were evaluated in desert tortoises (Gopherus agassizii). Tortoises were orotracheally intubated while awake and ventilated manually with 3-7% sevoflurane in oxygen (1 L/min) to achieve desired expired sevoflurane concentrations. Data, consisting of induction time, recovery time, systolic, diastolic, and mean ventricular pressures, heart rate, ventricular pH, blood gas values, and electrolytes, were collected prior to anesthesia and sequentially at 2.50% and 3.75% expired sevoflurane as measured at the junction of the endotracheal tube and the breathing circuit. Blood pressure was measured and blood samples were collected through a 25-ga needle passed through a cardiac access port that was placed while the tortoises were in dorsal recumbency. Mean (+/-SE) induction time was 2.55+/-0.55 min, recovery time was 27.58+/-7.55 min, and duration of anesthesia was 105+/-12 min. Mean (+/-SD) values for systolic, diastolic, and mean ventricular pressures in awake tortoises were 28+/-3 mm Hg, 22+/-2 mm Hg, and 24+/-2 mm Hg, respectively. Sevoflurane (2.5% expired) significantly decreased systolic (14+/-3 mm Hg), diastolic (12+/-1 mm Hg), and mean (13+/-1 mm Hg) ventricular pressures compared with those of awake tortoises. Ventricular pressures did not decrease further with increasing depth of anesthesia. Heart rate (32+/-4 beats/min) did not change significantly under sevoflurane anesthesia. Sevoflurane administration increased ventricular PO2 but did not change Na+, K+, or iCa++ concentrations. Sevoflurane appears to provide safe and effective anesthesia with rapid induction and recovery.

Anesthetics, Inhalation↗
PubMed1997

[Appendicitis in childhood].

From 1989 to 1995 high-resolution ultrasonography (US) was performed in 3,546 children (age: 1-17 years) with clinically suspected appendicitis. A total of 518 patients underwent laparotomy; 420 had histologically proven acute or perforated appendicitis (prevalence 11.8%). In these children, the sensitivity, specificity and overall accuracy of US examination were 90%, 97% and 96% respectively. The use of US in clinically doubtful acute abdomen may allow earlier diagnosis of acute appendicitis; in 1995 the rate of unnecessary appendectomy was reduced to 13%.

Abdomen, Acute↗
PubMed1997

Radiotelemetrically recorded blood pressure and heart rate changes in relation to plasma catecholamine levels during parturition in the conscious, unrestrained goat.

The aim of this study was to investigate the extent of sympathetic nervous system activation during parturition in four unrestrained goats. Chronically implanted radiotelemetry devices registered heart rate and arterial blood pressure around the clock and blood was sampled for determination of plasma adrenaline and noradrenaline concentrations before, during and after labour. Two goats delivered two kids after moderately intensive abdominal contractions. A third goat had dystocia, and was treated with prostaglandin F2 alpha. One normal kid and one mummified foetus were delivered manually. After milking, a third kid was born spontaneously. The fourth goat experienced severe abdominal contractions and delivered one kid. Mean blood pressure was 69 +/- 2 mmHg the day before parturition, increased gradually during the labour pains, and reached a maximal value of 120 +/- 7 mmHg when the head of the first kid was visible (P < or = 0.05). Heart rate was 134 +/- 4 beats min-1 the day before parturition and peaked when the first kid was born (159 +/- 6 beats min-1, P < or = 0.05), as did plasma adrenaline concentration (from 0.4 +/- 0.2 nmol L-1 to 2.7 +/- 1.2 nmol L-1, P < or = 0.05). The concentration of noradrenaline increased from 4.8 +/- 2.3 nmol L-1 to 12.2 +/- 8.4 nmol L-1 (P < or = 0.05), when the head of the first kid was visible. Expulsion of the second and third kids caused relatively smaller increases in blood pressure, heart rate and catecholamines than those seen with the first born kid. It is concluded that changes in pressure, heart rate and catecholamines during parturition are related to the different phases of labour and not to its duration or severity.

Animals↗
PubMed1997

Genetic alteration of alpha 2C-adrenoceptor expression in mice: influence on locomotor, hypothermic, and neurochemical effects of dexmedetomidine, a subtype-nonselective alpha 2-adrenoceptor agonist.

alpha 2-Adrenergic receptors (alpha 2-ARs) regulate many physiological functions and are targets for clinically important antihypertensive and anesthetic agents. Three human and mouse genes encoding alpha 2-AR subtypes (alpha 2A, alpha 2B, and alpha 2C) have been cloned. We investigated the involvement of the alpha 2C-AR in alpha 2-adrenergic pharmacology by applying molecular genetic techniques to alter the expression of alpha 2C-AR in mice. The effects of dexmedetomidine, a subtype-nonselective alpha 2-AR agonist, on monoamine turnover in brain and on locomotor activity were similar in mice with targeted inactivation of the alpha 2C-AR gene and in their controls, but the hypothermic effect of the alpha 2-AR agonist was significantly attenuated by the receptor gene inactivation. Correspondingly, another strain of transgenic mice with 3-fold overexpression of alpha 2C-AR in striatum and other brain regions expressing alpha 2C-AR showed normal reductions in brain monoamine metabolism and locomotor activity after dexmedetomidine, but their hypothermic response to the alpha 2C-AR agonists was significantly accentuated. The hypothermic effect of alpha 2-AR agonists thus seems to be mediated in part by alpha 2C-AR. Some small but statistically significant differences between the strains were also noted in brain dopamine metabolism. Lack of alpha 2C-AR expression was linked with reduced levels of homovanillic acid in brain, and mice with increased alpha 2C-AR expression had elevated concentrations of the dopamine metabolite compared with their controls.

Adrenergic alpha-Agonists↗
PubMed1995

Risk of physical assaults among student nurses.

This study was undertaken within two teaching hospitals (one general and one psychiatric) in a large health board. Its purpose was to compare the rates of physical assaults on student nurses with those on other grades of nursing staff, to explore the aetiological factors associated with attack, and to identify what preventive measures were in place and what support systems were available for affected staff. Data were collected from completed incident forms and from a semi-structured questionnaire administered to the student nurses. The rate of reported assault was much higher in the psychiatric hospital than the general hospital, but the severity of the assault was greater in the general hospital. Age and height were not risk factors for assaults. The study showed inadequate training, under-reporting of incidents, poor utilization of occupational health departments and a lack of support for victims of physical assaults.

Female↗
PubMed1993

[Pelvic vein thrombosis in protein C deficiency after infectious mononucleosis].

Subsequent to an infectious mononucleosis a 15 year old girl developed a thrombosis of the iliaca vein. Laboratory evaluation revealed a heterozygous form of protein C deficiency. An infusion with r-tPA (= recombinant tissue plasminogen activator) at a rate of 0.02 mg/kg BW/h over 96 hours failed to reopen the vessel. After intermittent heparin therapy longterm treatment with coumarin began. Three months later the iliaca vein was partially recanalised.

Adolescent↗
PubMed1992

Comparison of skin changes induced on mice by either group A type 12 or group G streptococci.

Adult Swiss webster mice were injected with 3 x 10(6) colony-forming units (cfu) of group G or 2.5 x 10(6) cfu of group A streptococci at intradermal injection sites on the right and left paralumbar areas of the back. The mice were sacrificed at intervals between 4 hours and 14 days post-injection (p.i.) and full thickness biopsies of skin 10 mm in diameter encompassing the sites of injection were taken. One tissue specimen was homogenized in PBS and plated to determine the number of cfu, while another was used for histopathological studies. The number of viable group A and group G streptococci in the tissue increased to 3 x 10(9) cfu by 96 hours p.i.: after 192 hours p.i. the group A cells had declined to 2.7 x 10(6) cfu compared to 1.1 x 10(8) cfu for group G cells. No streptococci of either group were detected at 336 hours (14 days p.i.). Gross edematous lesions induced by either streptococcus group were evident on all animals at 24 hours (p.i.). Group G streptococci lesions were larger and persisted longer than lesions induced by group A. Histological examination consistently revealed more inflammation and necrosis in tissue sections from mice injected with group G streptococci.

Animals↗
PubMed1986

Dual infection of the toe web caused by Trichophyton rubrum and Microsporum canis.

A case of tinea pedis caused by a dual infection with Trichophyton rubrum and Microsporum canis is reported. It is of particular interest because infections of the toe webs caused by M. canis are uncommon and the combination of T. rubrum and M. canis has not been reported. In addition, a marked difference in response to treatment with an imidazole (bifonazole) was observed.

Adult↗