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Biomedical subjects

R Macfarlane

Publications and source records attributed to R Macfarlane.

At least 19 recordsLinked to original sources
PubMed2006

Dissolution of porcine incisor pulps in sodium hypochlorite solutions of varying compositions and concentrations.

BACKGROUND: The solubility of dental pulp tissue in sodium hypochlorite has been extensively investigated but results have been inconsistent; due most likely to variations in experimental design, the volume and/or rate of replenishment of the solutions used and the nature of the tissues assessed. Traditionally, the sodium hypochlorite solutions used for endodontic irrigation in Australia have been either Milton or commercial bleach, with Milton being the most common. Recently, a range of Therapeutic Goods Administration (TGA) approved proprietary sodium hypochlorite solutions, which contain surfactant, has become available. Some domestic chlorine bleaches now also contain surfactants. The purpose of this study was to perform new solubility assessments, comparing Milton with new TGA approved products, Hypochlor 1% and Hypochlor 4% forte, and with a domestic bleach containing surfactant (White King). METHODS: Ten randomly assigned pulp samples of porcine dental pulp of approximately equal dimensions were immersed in the above solutions, as well as representative concentrations of sodium hydroxide. Time to complete dissolution was measured and assessed statistically. RESULTS: White King 4% showed the shortest dissolution time, closely followed by Hypochlor 4% forte. White King 1% and Hypochlor 1% each took around three times as long to completely dissolve the samples of pulp as their respective 4% concentrations, while Milton took nearly 10 times as long. The sodium hydroxide solutions showed no noticeable dissolution of the pulp samples. CONCLUSIONS: The composition and content of sodium hypochlorite solutions had a profound effect on the ability of these solutions to dissolve pulp tissue in vitro. Greater concentrations provided more rapid dissolution of tissue. One per cent solutions with added surfactant and which contained higher concentrations of sodium hydroxide were significantly more effective in dissolution of pulp tissue than Milton.

Animals↗
PubMed2006

Dead men and radiologists don't lie: a review of cadaveric and radiological studies of rotator cuff tear prevalence.

INTRODUCTION: Rotator cuff tears are a common pathology, with a varied prevalence reported. PATIENTS AND METHODS: A literature review was undertaken to determine the cadaveric and radiological (ultrasonography and magnetic resonance imaging [MRI]) prevalence of rotator cuff tear. The radiological studies were subdivided into symptomatic and asymptomatic subjects. RESULTS: Cadaveric rotator cuff tears were found in 4629 shoulders of which only 2553 met the inclusion criteria. The prevalence of full-thickness tears was 11.75% and partial thickness 18.49% (total tears 30.24%). The total tear rate in ultrasound asymptomatic was 38.9% and ultrasound symptomatic 41.4%. The total rate in MRI asymptomatic was 26.2% whilst MRI symptomatic was 49.4%. DISCUSSION: The unselected cadaveric population should contain both symptomatic and asymptomatic subjects. A prevalence of tears between the symptomatic and asymptomatic radiological groups would be expected. However, apart from the MRI asymptomatic group, the radiological prevalence of rotator cuff tears exceeds the cadaveric. CONCLUSIONS: Rotator cuff tears are frequently asymptomatic. Tears demonstrated during radiological investigation of the shoulder may be asymptomatic. It is important to correlate radiological and clinical findings in the shoulder.

Aged↗
PubMed2004

Mortality in patients with diabetic neuropathic osteoarthropathy (Charcot foot).

OBJECTIVE: To determine the mortality of a population of patients diagnosed with Charcot neuropathic osteoarthropathy managed by a single specialist unit and to compare the results with a control population. METHODS: We have undertaken a retrospective analysis of all cases of Charcot foot on the comprehensive database which has been maintained at the specialist diabetic foot clinic at the City Hospital, Nottingham since 1982. Survival and the incidence of amputation (major and minor) was compared with a control population referred with uncomplicated neuropathic ulceration. Controls were individually matched for gender, age (+/-2 years), disease type, disease duration (+/-2 years) and year of referral (+/-3 years). RESULTS: Forty-seven cases (21 female, 26 male) of Charcot foot were identified, of whom 18 (38.3%) had Type 1 diabetes. Mean age and disease duration at presentation were 59.2 +/- 13.4 (sd) and 16.2 +/- 11.2 years, compared with 59.7 +/- 12.6 and 16.3 +/- 11.2 years, respectively, in the controls. Twenty-one (44.7%) of those with Charcot had died, after a mean interval of 3.7 +/- 2.8 years. This compared with 16 (34.0%) after a mean 3.1 +/- 2.7 years in the control group. Mean duration of follow-up in the survivors was 4.7 +/- 4.9 years (Charcot) and 5.3 +/- 3.9 years (controls). A total of 11 (23.4%) Charcot patients had had a major amputation on the side of the index lesion, compared with five (10.6%) controls. There was no difference between the two groups (P > 0.05, Chi-square). CONCLUSIONS: The mortality in this group of patients with Charcot foot was higher than expected. Nevertheless, there was no difference between those with Charcot and those with uncomplicated neuropathic ulceration. It is possible that it is neuropathy, rather than Charcot osteoarthropathy, which is independently associated with increased mortality in diabetes. The mechanism underlying any such association is not known. There is a need for a formal, prospective, multicentre study to investigate the life expectancy and cardiovascular risk of those with Charcot osteoarthropathy.

Adult↗
PubMed2003

Optical detection of hot-electron spin injection into GaAs from a magnetic tunnel transistor source.

Injection of spin-polarized hot-electron current from a magnetic tunnel transistor into GaAs is demonstrated by the observation of polarized light emission from a GaAs/In(0.2)Ga(0.8)As multiple quantum well light-emitting diode. Electroluminescence from the quantum wells shows a polarization of approximately 10% after subtraction of a linear background polarization. The polarization shows a strong dependence on the bias voltage across the diode, which may originate from changes in the electron spin relaxation rate in the quantum wells under varying bias conditions.

Journal Article↗
PubMed2002

Cauda equina syndrome: what is the relationship between timing of surgery and outcome?

The role of urgent surgery in improving the outcome of cauda equina compression following lumbar central disc prolapse remains controversial. Some series claim improved outcome from emergency decompression whilst others have found no benefit. Resolution of this issue is important because the opportunity to reverse neurological impairment may already have been lost by the time of hospital admission. Removal of a large central disc prolapse can be considerably more difficult than routine discectomy, and may require an extensive exposure. When performed under less than optimal conditions, as often exists in the emergency setting, surgery may even add to rather than alleviate morbidity. This article reviews the pathophysiology of cauda equina syndrome, its definition, and the controversies surrounding management. Where urinary retention with overflow incontinence extists at presentation we believe that urgent decompression confers no benefit.

Decompression, Surgical↗
PubMed2001

Post-partum retreatment with iridium-192 wire brachytherapy for meningioma recurring in pregnancy.

We report the case history of a female patient who had received radical radiotherapy for a malignant meningioma at the age of 11 years. Thirteen years later, during her first pregnancy, she presented with a recurrence. The tumour was surgically debulked, but complications related to postoperative sepsis, the location of the tumour, and the extent of her previous treatment made the delivery of adjuvant radiotherapy problematic. The tumour bed was treated using an interstitial implant of 192Ir wires to a dose of 60 Gy in 100 hours. The patient remains well with no evidence of tumour recurrence or brain necrosis 2 years later. We discuss the role of female sex hormones in meningioma and the difficulties of radical retreatment of tumours in the central nervous system. The various techniques of brachytherapy in the brain are highlighted. The specific advantages of 192Ir in this patient are discussed.

Adult↗
PubMed2001

Occipito-clival intradiploic meningocoele following skull fracture in infancy.

An adolescent presented with an intradiploic meningocoele 11 years after an occipital skull fracture. Surgical treatment consisted initially of cranioplasty, but the lesion then progressed to involve much of the skull base, requiring cystoperitoneal shunt insertion. The pathogenesis and treatment of post-traumatic intradiploic meningocoele is discussed.

Cerebrospinal Fluid Shunts↗
PubMed2001

Prospective study of the incidence, aetiology and outcome of adult lower respiratory tract illness in the community.

BACKGROUND: Acute lower respiratory tract illness in previously well adults is usually labelled as acute bronchitis and treated with antibiotics without establishing the aetiology. Viral infection is thought to be the cause in most cases. We have investigated the incidence, aetiology, and outcome of this condition. METHODS: Previously well adults from a stable suburban population consulting over one year with a lower respiratory tract illness were studied. For the first six months detailed investigations identified predetermined direct and indirect markers of infection. Evidence of infection was assessed in relation to presenting clinical features, indirect markers of infection, antibiotic use, and outcome. RESULTS: Consultations were very common, particularly in younger women (70/1000 per year in previously well women aged 16-39 years), mainly in the winter months; 638 patients consulted, of whom 316 were investigated. Pathogens were identified in 173 (55%) cases: bacteria in 82 (Streptococcus pneumoniae 54, Haemophilus influenzae 31, Moraxella catarrhalis 7), atypical organisms in 75 (Chlamydia pneumoniae 55, Mycoplasma pneumoniae 23), and viruses in 61 (influenza 23). Seventy nine (24%) had indirect evidence of infection. Bacterial and atypical infection correlated with changes in the chest radiograph and high levels of C reactive protein but not with (a) the GP's clinical assessment of whether infection was present, (b) clinical features other than focal chest signs, and (c) outcome, whether or not appropriate antibiotics were prescribed. CONCLUSIONS: Over 50% of patients have direct and/or indirect evidence of infection, most commonly bacterial and atypical pathogens, but the outcome is unrelated to the identified pathogens. Many patients improve without antibiotics and investigations do not help in the management of these patients. GPs can reassure patients of the causes and usual outcome of this self-limiting condition.

Acute Disease↗
PubMed1997

Influence of patients' expectations on antibiotic management of acute lower respiratory tract illness in general practice: questionnaire study.

OBJECTIVE: To assess patients' views and expectations when they consult their general practitioner with acute lower respiratory symptoms and the influence these have on management. DESIGN: General practitioners studied consecutive, previously well adults and recorded clinical data, the certainty regarding their prescribing decision, and the influence of non-clinical factors on that decision. Patients completed a questionnaire at home after the consultation. SETTING: 76 doctors from suburban, inner city, and rural practices. SUBJECTS: 1014 eligible patients entered; 787 (78%) returned the questionnaire. MAIN OUTCOME MEASURES: The views of the patient, the views of and antibiotic prescription by the doctor. RESULTS: Most patients thought that their symptoms were caused by an infection (662) and that antibiotics would help (656) and had both wanted (564) and expected (561) such a prescription. 146 requested an antibiotic, 587 received one. Of the 643 patients who thought they had an infection, 582 wanted an antibiotic and thought it would help. Severity of symptoms did not relate to wanting antibiotics. For those prescribed antibiotics, their doctor thought they were definitely indicated in only 116 cases and not indicated in 126. Patient pressure most commonly influenced the decision to prescribe even when the doctor thought antibiotics were not indicated. Doctors considered antibiotics definitely indicated in only 1% of the group in whom patient pressure influenced the prescribing decision. Patients who did not receive an antibiotic that they wanted were much more likely to express dissatisfaction. Dissatisfied patients reconsulted for the same symptoms twice as often as satisfied patients. CONCLUSION: Patients presenting with acute lower respiratory symptoms often believe that infection is the problem and antibiotics the answer. Patients' expectations have a significant influence on prescribing, even when their doctor judges that antibiotics are not indicated.

Adult↗
PubMed1997

Contemporary use of antibiotics in 1089 adults presenting with acute lower respiratory tract illness in general practice in the U.K.: implications for developing management guidelines.

Respiratory symptoms are the most common cause of general practitioner (GP) consultation, and hospital-based specialists are often called on to provide management guidelines, particularly in the area of antibiotic prescribing. The present authors have assessed factors associated with antibiotic use by 115 GPs when managing 1089 adults with an acute lower respiratory tract illness, including cough. They prescribed antibiotics to three-quarters of patients, but felt antibiotics to be definitely indicated in less than one-third of these cases and not needed in one-fifth. Univariate analysis revealed that antibiotics were prescribed more frequently by older GPs for older patients in the presence of underlying disease, discoloured sputum, shortness of breath, wheeze, fever, signs on chest examination, and 'other factors'. Multivariate logistic regression confirmed an independent effect for all these findings except for the presence of underlying disease, shortness of breath and wheeze. 'Other factors' included patient 'pressure' and social factors, and GP work pressure or prior experience with the patient. These factors were an important influence on prescribing, especially if the GP felt an antibiotic was not indicated. Amoxycillin was the first choice (58% of total) except where the patient had recently received antibiotics for the same illness. Broader spectrum antibiotics were used more commonly in patients with chronic lung disease, discoloured sputum, chest signs on examination and where the GP felt antibiotics were indicated. However, these antibiotics were also prescribed to 14% of previously well patients. General practitioners used a wide variety of terms to describe the illness with little consistency or structure. The decision concerning the use and choice of antibiotics and the confidence with which the GP makes that decision is a complex interaction between patient, doctor and disease, being affected not only by clinical features but also by the social and psychological elements of the presenting problem. Such issues need to be appreciated by hospital specialists when called on to advise on developing relevant guidelines for primary care.

Acute Disease↗
PubMed1996

Planning and assessing a cross-training initiative with multi-skilled employees.

BACKGROUND: An improvement initiative begun by nurses at Parkview Episcopal Medical Center (Pueblo, Colo) to develop patient-focused care delivered by multiskilled workers followed a quality improvement methodology. Implementation of the new care delivery system on a model unit--2 South--provided the opportunity to plan, analyze data, and make changes as appropriate. Parkview's indoctrination of the teachings of W. Edwards Deming has helped leaders and staff realize the integral role of training in improvement activities. In his 14 points, Deming emphasizes the importance of employee education and of the employee having a clear understanding of his or her job. The time and money put into up-front education should help ensure the long-term success of this initiative. DEFINING THE CAREPARTNER: Three new multi-skilled positions were developed on 2 South--a Personal CarePartner, a Business CarePartner, and a Clinical CarePartner. By cross-training each of these roles to perform duties formerly done by centralized departments, 2 South was able to cut costs and time while ensuring quality care. TRAINING THE CAREPARTNER: An internally developed training program provided the new CarePartners with up-front education to prepare them to deliver patient-centered care. RESULTS: 2 South has experienced drops in patient falls and medication errors--areas that are often negatively affected when multi-skilled programs are instituted. Patient and physician surveys have shown increased satisfaction with care provided on the unit. The increased efficiency of the model unit has produced these outcomes while cutting costs substantially. LESSONS LEARNED: The interdisciplinary team coordinating the improvement project learned many lessons in the process, including the importance of communication, education, and a sense of humor.

Clinical Competence↗
PubMed1995

Encephaloceles of the anterior cranial fossa.

From a total of 114 encephaloceles treated surgically at The Hospital for Sick Children in the 15 years to 1994, the case records of 17 patients with sincipital and 5 patients with basal defects were reviewed retrospectively. The condition was evident at birth in 64% of patients, while the remainder presented with either cerebrospinal fluid (CSF) rhinorrhea, nasal obstruction, or feeding difficulty. Hypertelorism affected 73% of patients. All encephaloceles were repaired transcranially, at a mean age of 2 years, usually by means of an intradural pericranial graft. Five children with gross hypertelorism underwent orbital translocation at the time of encephalocele repair. Of those not corrected, primary and secondary hypertelorism regressed in most instances where the encephalocele was treated before the age of 2 years. There were no deaths. The only case of CSF rhinorrhea occurred in a patient with a basal defect, in whom intradural repair was not possible because of adherence of diencephalic structures to the sac wall. Hypertelorism recurred in 1 patient after orbital translocation, requiring recorrection 2 years later. One patient with untreated secondary hypertelorism failed to regress after the encephalocele was excised at the age of 4 months. Developmental outcome was normal in 59% of children, whilst 18% have mild mental or physical disability, and 23% are severely impaired. A child with a sincipital or basal defect and mild hypertelorism should have the encephalocele treated in early childhood to allow the facial skeleton to remodel with growth. When an encephalocele is accompanied by gross hypertelorism or a facial cleft, one-stage correction can be undertaken safely in early childhood with minimal mortality and acceptable morbidity.

Encephalocele↗
PubMed1995

Absence of the greater sphenoid wing in neurofibromatosis type I: congenital or acquired: case report.

unilateral absence of the greater wing of the sphenoid bone is a distinctive but uncommon manifestation of Type I neurofibromatosis, which has until now been regarded as a developmental anomaly of mesodermal origin. A computed tomographic scan was obtained in a 4-week-old infant with an abnormal left eye. The scan demonstrated an intact ipsilateral sphenoid bone, except for minor expansion of the medial end of the left superior orbital fissure. Another computed tomographic scan was obtained 6 years later, when the child had café-au-lait patches, axillary freckling, Lisch nodules, and left phthisis bulbi. This later scan showed typical sphenoid dysplasia. Much of the greater wing was absent, and the anterior temporal pole was displaced anteriorly. In this article, we discuss the implications of this case in terms of the cause of this condition and the diagnosis of Type I neurofibromatosis.

Eye Abnormalities↗
PubMed1995

Matrotrophic viviparity in the yellowtail rockfish Sebastes flavidus

A capacity for matrotrophic viviparity was established in the yellowtail rockfish Sebastes flavidus (Teleostei: Scorpaeniformes). The incorporation of radiolabel into embryos from [14C]phosphatidylcholine present in the maternal serum during gestation provided the first in vivo demonstration of matrotrophy of phospholipid for any viviparous teleost and of any nutrient for a member of the genus Sebastes. Radiolabel content increased as embryos progressed through ontogeny. Serum proteins of 170 kDa, present in vitellogenic and embryogenic females, but not in earlier stages, in immature females or in males, indicated the presence of vitellogenin in pregnant females and, thus, the potential for matrotrophic supplementation to yolk sequestered before fertilization. The retention of higher molecular mass proteins and highly phosphorylated proteins and the maintenance of total protein content in yolk during early to mid embryogenesis argue for exogenous maternal supply during gestation. As ovarian development proceeded from the oocyte through successive embryonic stages, the distribution of yolk proteins shifted from higher (67&shy;97 kDa) to lower molecular masses (<70 kDa). The results of these experimental studies corroborate data from field investigations showing that yellowtail rockfish can matrotrophically supplement embryo nutrients obtained before fertilization. Thus, yellowtail rockfish represent a teleost species positioned within the viviparity continuum and not at its extremes.

Journal Article↗