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Biomedical subjects

A W Duncan

Publications and source records attributed to A W Duncan.

At least 19 recordsLinked to original sources
PubMed2006

Adenotonsillar surgery in morbidly obese children: routine elective admission of all patients to the intensive care unit is unnecessary.

Morbidly obese children undergoing adenotonsillectomy, often with co-morbid obstructive sleep apnoea, may be considered at a higher risk of postoperative respiratory compromise. This retrospective study aimed to assess the frequency and severity of postoperative respiratory complications in these patients and to identify preoperative risks factors for such morbidity. Medical and nursing chart review of all consecutive elective post-adenotonsillectomy admissions of morbidly obese children (defined as >95th centile for body mass index adjusted for age and gender) to our intensive care unit over a 30-month period was performed. A total of 26 morbidly obese children were identified. The majority (14/26) had an uncomplicated recovery following surgery. Of those cases that required postoperative intervention, 10 patients required supplemental oxygen with or without suctioning and/or repositioning alone, whilst two required continuous positive airway pressure therapy. No patient required re-intubation. An oxygen saturation nadir of < 70% and the presence of more than one central apnoea, noted on preoperative overnight polysomnography, were associated with postoperative respiratory complications requiring intervention. Although the intervention group were younger, more obese and had a higher respiratory disturbance index, none of these factors were statistically significant. Routine admission to the paediatric intensive care unit of all morbidly obese children undergoing adenotonsillectomy may be unnecessary, once a suitable high level of nursing is available in an alternative setting, to administer simple positional and suctioning intervention and to perform regular patient observation. Special consideration should be given to the postoperative nursing environment for those patients with a SaO2 nadir < 70% noted preoperatively, indicating the presence of a significant central disease component.

Adenoidectomy↗
PubMed2003

Prolonged per-laryngeal endotracheal intubation in children: 40 years on.

Because tracheostomy has a very high complication rate in small children, prolonged mechanical ventilation was not performed satisfactorily in infants until a technique was developed that allowed prolonged per-laryngeal endotracheal intubation in children. Plastic polyvinyl chloride endotracheal tubes were introduced in the 1950s; they soften at body temperature, and are much less likely to cause subglottic stenosis than endotracheal tubes made from metal or rubber. The first account of prolonged per-laryngeal intubation of infants using polyvinyl chloride tubes was written by Dr Bernard Brandstater, and this remarkable document is reproduced here. It sets out all the important principles of endotracheal intubation in children: the tube must fit easily through the cricoid ring, it must be firmly fixed in place with the tip in the mid trachea, meticulous humidification and suction are essential, and the tube should be changed only if there are signs of obstruction.

Child, Preschool↗
PubMed2001

Testican in human blood.

Testican is a highly conserved, differentially expressed gene product of unknown function. Since testican is expressed by human endothelial cells and includes a signal sequence, it was our hypothesis that testican protein would be present in blood. We have developed chicken antibodies specific for testican sequence near the N-terminal and identified a 130-kDa form of testican in human plasma. This is much larger than the calculated molecular weight of the encoded polypeptide, suggesting glycosylation of this plasma protein, and large forms of recombinant testican produced in culture were found to include chondroitin sulfate. The 130-kDa form of testican is unstable in plasma. It is converted to smaller stable forms by separable plasma factors that can be blocked by certain serine protease inhibitors. Testican size conversion may be important in its functional activation or decay. One testican domain has strong homology to thyropin-type cysteine protease-inhibitors. Thus, testican may have a function related to protease inhibition in the blood.

Amino Acid Sequence↗
PubMed2001

Second malignancies in children: the usual suspects?

The aim of this article is to provide an up to date review of second malignant neoplasms (SMN's) following treatment for childhood cancer, referring to their incidence, the role of genetic factors, and how the primary malignancy and treatment received influence the type, site and prognosis of SMN's. The role of genetic factors will be discussed as far as they impact upon a predisposition to later development of SMN's. The primary malignancies that have important associations with SMN's will then be discussed, in particular Hodgkin's disease, retinoblastoma and acute lymphoblastic leukaemia. The important second malignancies will be highlighted, including tumours of the CNS and thyroid, osteosarcoma, secondary acute myeloid leukaemia and melanoma. Emphasis will be put upon identifying which patients are most likely to suffer from these tumours. An important part of the article are case histories. These are provided in combination with illustrations as a useful adjunct to the text, with a particular emphasis on radiological features, diagnosis and screening. Finally, the important but different roles of causal agents, in particular chemotherapy and radiotherapy are highlighted.

Central Nervous System Neoplasms↗
PubMed2001

Second malignancies in children: the usual suspects?

The aim of this article is to provide an up to date review of second malignant neoplasms (SMN's) following treatment for childhood cancer, referring to their incidence, the role of genetic factors, and how the primary malignancy and treatment received influence the type, site and prognosis of SMN's. The role of genetic factors will be discussed as far as they impact upon a predisposition to later development of SMN's. The primary malignancies that have important associations with SMN's will then be discussed, in particular Hodgkin's disease, retinoblastoma and acute lymphoblastic leukaemia. The important second malignancies will be highlighted, including tumours of the CNS and thyroid, osteosarcoma, secondary acute myeloid leukaemia and melanoma. Emphasis will be put upon identifying which patients are most likely to suffer from these tumours. An important part of the article are case histories. These are provided in combination with illustrations as a useful adjunct to the text, with a particular emphasis on radiological features, diagnosis and screening. Finally, the important but different roles of causal agents, in particular chemotherapy and radiotherapy are highlighted.

Adolescent↗
PubMed2001

Diagnosing insulin resistance in the general population.

OBJECTIVE: Difficulties in measuring insulin sensitivity prevent the identification of insulin-resistant individuals in the general population. Therefore, we compared fasting insulin, homeostasis model assessment (HOMA), insulin-to-glucose ratio, Bennett index, and a score based on weighted combinations of fasting insulin, BMI, and fasting triglycerides with the euglycemic insulin clamp to determine the most appropriate method for assessing insulin resistance in the general population. RESEARCH DESIGN AND METHODS: Family history of diabetes, BMI, blood pressure, waist and hip circumference, fasting lipids, glucose, insulin, liver enzymes, and insulin sensitivity index (ISI) using the euglycemic insulin clamp were obtained for 178 normoglycemic individuals aged 25-68 years. Product-moment correlations were used to examine the association between ISI and various surrogate measurements of insulin sensitivity. Regression models were used to devise weights for each variable and to identify cutoff points for individual components of the score. A bootstrap procedure was used to identify the most useful predictors of ISI. RESULTS: Correlation coefficients between ISI and fasting insulin, HOMA, insulin-to-glucose ratio, and the Bennett index were similar in magnitude. The variables that best predicted insulin sensitivity were fasting insulin and fasting triglycerides. The use of a score based on Mffm/I = exp[2.63 - 0.28ln(insulin) - 0.31ln(TAG)] rather than the use of fasting insulin alone resulted in a higher sensitivity and a maintained specificity when predicting insulin sensitivity. CONCLUSIONS: A weighted combination of two routine laboratory measurements, i.e., fasting insulin and triglycerides, provides a simple means of screening for insulin resistance in the general population.

Adult↗
PubMed2000

Distribution of testican expression in human brain.

Testican is a putative extracellular heparan/ chondroitin sulfate proteoglycan of unknown function that is expressed in a variety of human tissues at widely different levels but is most abundant in the brain. In mice, testican mRNA has been detected only in brain and it is therefore likely to have an important function in the central nervous system. RNA blot analysis reveals the relative intensity of testican in various regions of the human brain. Levels of testican message are most pronounced in the thalamus, hippocampus, occipital lobe, nucleus accumbens, temporal lobe, and caudate nucleus, with somewhat lower levels in the cerebral cortex, medulla oblongata, frontal lobe, amygdala, putamen, spinal cord, substantia nigra, and cerebellum. In situ hybridization reveals the cellular distribution of the mRNA within these areas to be highest in neurons and in choroid plexus epithelium, and moderately lower in ependymal cells lining the ventricles and in vascular endothelial cells. Testican mRNA is not detected in oligodendrocytes or in most astrocytes. However, astrocytes in regions of reactive gliosis do express testican mRNA. These findings, along with a cysteine-rich pattern similarity to neurocan, brevican, versican, and other proteoglycans found in brain, suggest that testican may be a part of the specialized extracellular matrix of the brain.

Basal Ganglia↗
PubMed1999

Radiological features of non-accidental injury.

Non-accidental injury is not uncommonly met in clinical practice. One should be aware of its presentation, the radiographic signs suspicious of abuse and the appropriate further imaging assessment to confirm or refute the diagnosis. Erroneous diagnosis can have grave consequences.

Child↗
PubMed1998

The role of magnetic resonance imaging in the preoperative assessment of anorectal anomalies.

The role of magnetic resonance imaging (MRI) compared to other investigations in providing information relevant to and affecting surgical management in patients with anorectal anomalies (ARA) was studied in two groups of patients. In group 1 a pilot study was done in 9 patients with colostomy for high ARA awaiting posterior sagittal anorectoplasty. These patients had MRI, plain radiographs, a distal loopogram through the mucous fistula, ultrasound scans of the spinal cord and urinary tract, and a micturating cystourethrogram. The level of bowel and spinal-cord termination was correctly determined in all patients by MRI and conventional investigations. The presence or absence of a fistula, urological abnormalities, and bony abnormalities of the pelvis and spine were better visualized by conventional investigations than with MRI. The striated-muscle complex (SMC) was well-visualized by MRI, the thickness accurately graded, and the findings confirmed at operation. The information on muscle thickness and the presence or absence of a fistula was interesting, but played no part in decisions made about surgical management, and the operative technique was not altered. In group 2 the patients were much older and had MRI for persistent problems, mainly soiling; 6 had low lesions and 6 had high lesions. Three patients with low lesions were found to have intraspinal abnormalities on MRI; 4 were found to have malpositioned bowel in the SMC, which was again accurately visualized and graded. Therefore, in 7/12 patients of this group a surgically correctable abnormality was found. We conclude that MRI has no role as a primary investigation in patients with high ARA, but it is useful if there are suspected spinal-cord problems or persistent problems after definitive surgery.

Anal Canal↗
PubMed1997

Lifestyle intervention in people with insulin-dependent diabetes mellitus (IDDM).

OBJECTIVE: To investigate the impact of intensive lifestyle education on dietary practices, exercise and metabolic measurements in people with insulin-dependent diabetes mellitus (IDDM). DESIGN: Sixty-one volunteer subjects with IDDM were randomised to intensive (Group 1) or standard (Group 2) education programmes for six months. During a second six month period of observation Group 1 subjects received routine surveillance for their condition and those in Group 2 were given intensive advice (phase 2). Current insulin regimens were modified to optimise glycaemic control before the start of the intervention phase. Nutrient intakes, weight, blood pressure, glycated haemoglobin (HbA1), plasma lipids, lipoproteins and maximal oxygen consumption (VO2 max) were measured at the time of recruitment and at three monthly intervals during the trial and phase 2. SETTING: Department of Human Nutrition at the University of Otago. RESULTS: Glycated haemoglobin decreased significantly in both groups between recruitment and randomisation, the improvement being sustained during the six months of the randomised trial and for group 1 during the six months of post trial observation. A further decrease was seen in Group 2 during the second six month period when they were given intensive advice. Comparable changes were seen with total and low density lipoprotein (LDL) cholesterol in Group 1 during the trial, but significant decreases were only seen in Group 2 in association with intensive intervention (phase 2). These changes occurred in parallel with increases in intakes of carbohydrate and monounsaturated fatty acids, a reduction in intakes of total and saturated fat, and an improvement in maximum oxygen consumption. CONCLUSIONS: A lifestyle programme for people with IDDM results in modest changes in diet and exercise habits sufficient to improve measures of glycaemic control and lipoprotein mediated risk of coronary heart disease independent of changes in insulin regime. More innovative approaches to achieve lifestyle changes are required to meet current recommendations which in turn are likely to produce even greater beneficial changes than those observed here.

Adult↗
PubMed1996

Unusual metaphyseal disturbance in two kittens.

This report describes the presenting features, radiographic changes, biochemical alterations and clinical progress of two kittens, from separate litters, which were found to have a growth plate disturbance initially diagnosed and treated as vitamin D3-dependent rickets, but subsequently suspected to be a metaphyseal chondrodysplasia.

Animals↗
PubMed1996

Early focal abnormalities on chest radiographs and respiratory prognosis in children with cystic fibrosis.

The variable rate of progression of respiratory disease in cystic fibrosis demands reliable prognostic markers for rational treatment. This study aims to determine whether or not focal abnormalities on chest radiographs during the early clinical course of cystic fibrosis could be used as such a marker. A retrospective review of patient records was carried out. Demographic details, genotype, presentation, and course of respiratory disease over the first 6 years were recorded for all patients, together with spirometry and chest radiograph scores at 7 and 13 years for surviving patients. Comparison was made between those with and those without documented focal opacification on chest radiography during the first 6 years of life. 30 patients satisfied the study entry criteria and had complete records available. Of these, 17 had focal consolidation documented during the first 6 years, and 13 did not. Survival was significantly worse in those with previous consolidation (p < 0.01), as was peak expiratory flow at 7 years (p = 0.02). There were no other statistically significant differences between the groups, although those with previous consolidation apparently had worse lung function and more advanced disease on chest radiography at both 7 and 13 years. This study suggests that early focal chest radiographic abnormalities may predict a poorer outcome in cystic fibrosis.

Adolescent↗
PubMed1995

Magnetic resonance imaging and magnetic resonance angiography in long term survivors of acute lymphoblastic leukemia treated with cranial irradiation.

BACKGROUND: Successful treatment of acute lymphoblastic leukemia (ALL) has resulted in an increasing number of patients whose disease is cured. This treatment includes cranial irradiation as prophylaxis against central nervous system relapse. The late effects of irradiation are well documented, but their incidence is unknown. The authors investigated the late effects of this treatment modality further by scanning 35 long term survivors of ALL who received cranial irradiation. METHODS: Thirty-five survivors of ALL with no known complication of treatment were included in this study. They were examined with magnetic resonance imaging (MRI) of the brain and magnetic resonance angiography (MRA) of the circle of Willis. A control group of 24 patients who were cured of other childhood malignancies without exposure to cranial irradiation also were scanned. RESULTS: Fifteen of 35 (43%) abnormalities were found in the study group versus 4/24 (17%) in the control group. Excluding minor atrophic changes that are known to be produced by irradiation and chemotherapy, there were 9/35 (26%) abnormalities in the study group and 1/24 (4%) in the control group (P < 0.05). These abnormalities included three tumors, a meningioma, a paranasal sinus rhabdomyosarcoma, and an anaplastic astrocytoma. In addition, there were two cases of large vessel vasculopathy, two small cystic infarcts, one diffuse white matter abnormality, and one cryptic vascular malformation. The abnormal control patient had a cerebellar infarct. CONCLUSION: Complications of cranial irradiation in the treatment of ALL appear to be more frequent than currently are appreciated. That these complications include tumors that are potentially treatable suggests that screening may be valuable for these patients.

Adolescent↗