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Biomedical subjects

D Turnbull

Publications and source records attributed to D Turnbull.

At least 19 recordsLinked to original sources
PubMed2006

Treatment for mitochondrial disorders.

BACKGROUND: Mitochondrial respiratory chain disorders are the most prevalent group of inherited neurometabolic diseases. They present with central and peripheral neurological features usually in association with other organ involvement including the eye, the heart, the liver, and kidneys, diabetes mellitus and sensorineural deafness. Current treatment is largely supportive and the disorders progress relentlessly causing significant morbidity and premature death. Vitamin supplements, pharmacological agents and exercise therapy have been used in isolated cases and small clinical trials, but the efficacy of these interventions is unclear. OBJECTIVES: To determine whether there is objective evidence to support the use of current treatments for mitochondrial disease. SEARCH STRATEGY: We searched the Cochrane Neuromuscular Disease Group trials register (searched September 2003), the Cochrane Central Register of Controlled Trials, MEDLINE (January 1966 to October 3 2003), EMBASE (January 1980 to October 3 2003) and the European Neuromuscular Centre (ENMC) clinical trials register, and contacted experts in the field. SELECTION CRITERIA: We included randomised controlled trials (including crossover studies) and quasi-randomised trials comparing pharmacological treatments, and non-pharmacological treatments (vitamins and food supplements), and physical training in individuals with mitochondrial disorders. The primary outcome measures included an improvement in muscle strength and/or endurance, or neurological clinical features. Secondary outcome measures included quality of life assessments, biochemical markers of disease and negative outcomes. DATA COLLECTION AND ANALYSIS: Details of the number of randomised patients, treatment, study design, study category, allocation concealment and patient characteristics were extracted. Analysis was based on intention to treat data. We planned to use meta-analysis, but this did not prove necessary. MAIN RESULTS: Six hundred and seventy-eight abstracts were reviewed, and six fulfilled the entry criteria. Two trials studied the effects of co-enzyme Q10 (ubiquinone), one reporting a subjective improvement and a significant increase in a global scale of muscle strength, but the other trial did not show any benefit. Two trials used creatine, with one reporting improved measures of muscle strength and post-exercise lactate, but the other reported no benefit. One trial of dichloroacetate showed an improvement in secondary outcome measures of mitochondrial metabolism, and one trial using dimethylglycine showed no significant effect. AUTHORS' CONCLUSIONS: There is currently no clear evidence supporting the use of any intervention in mitochondrial disorders. Further research is needed to establish the role of a wide range of therapeutic approaches.

Creatine↗
PubMed2006

Screening for colorectal cancer by faecal occult blood test: why people choose to refuse.

To better understand the personal barriers that limit participation in faecal occult blood test (FOBT) screening for colorectal cancer, non-participants from a recent screening initiative were sent detailed questionnaires, defining their reasons for not participating, as well as how to make screening more attractive. The important barrier was procrastination. The type of FOBT kit offered influenced the reasons for not participating. Convenient FOBT and greater general practitioner involvement may be important for optimizing community acceptance of FOBT-based screening.

Aged↗
PubMed2006

Task force guidelines handbook: EFNS guidelines on diagnosis and management of fatty acid mitochondrial disorders.

Guidelines in the diagnosis and current dietary treatment of long-chain fatty acid (LCFA) defects have been collected according to evidence-based medicine. Since the identification of carnitine and carnitine palmitoyltransferase deficiency more than 25 years ago, nearly every enzymatic step required for beta-oxidation has been associated with an inherited metabolic disorder. These disorders effectively preclude the use of body fat as an energy source. Clinical consequences can range from no symptoms to severe manifestations including cardiomyopathy, hypoglycaemia, peripheral neuropathy and sudden death. A diet high in carbohydrates, diet with medium-chain triglycerides and reduced amount of LCFA has a beneficial effect (class IV evidence) and in appropriate deficiency states carnitine and riboflavin are used (good practice points).

Advisory Committees↗
PubMed2005

Performance of breathing filters under wet conditions: a laboratory evaluation.

INTRODUCTION: Heat and moisture exchangers in combination with a bacterial and viral filter (HMEF) are widely used during general anaesthesia. Excess patient secretions occluding the HMEF have been responsible for previous case reports of airway obstruction. A previous study suggested that differences in HMEF design might contribute to filter obstruction under wet conditions. METHODS: We tested 14 types of HMEF under wet conditions to establish which design features contributed to HMEF obstruction. Incremental amounts of saline were added to each filter. The pressure across the filter was measured with an air flow of 60 litre min(-1). RESULTS: We observed that saline added to the filter was often not easily visible to the casual observer. This concealment volume varied between filters. Ceramic hydrophobic pleated-membrane filters did not absorb saline and their resistance did not change. The composite filter where the moisture exchange component was either polyurethane foam or cellulose absorbed saline and contributed to a rise in resistance of 70-480% with the higher value more typical of the cellulose-paper-based HMEF. CONCLUSION: The ideal HMEF for use during general anaesthesia should prevent the passage of viral, bacterial and prion material, should provide this filtration performance even under wet conditions, should supplement humidification of the inspired air and anaesthetic gases and should not increase respiratory work. We have identified large variations in HMEF performance under wet conditions. Users should be aware of performance variation in HMEFs and use a filter suited to the intended application.

Air Pressure↗
PubMed2005

Ocular motility findings in chronic progressive external ophthalmoplegia.

AIMS: To characterise the ocular motility features of chronic progressive external opthalmoplegia by quantitative and semiquantitative means. To assess the prevalence of diplopia and the binocular adaptations to nonaligned visual axes. METHOD: We studied 25 patients with chronic progressive external ophthalmoplegia. In each case muscle biopsies were consistent with mitochondrial myopathy. All patients underwent cover test in the primary position, assessment of binocular status, and measurement of uniocular fields of fixation using the Goldmann perimeter. RESULTS: A total of 23 (92%) patients had an exo-deviation, with six (26%) of those having an associated vertical deviation: 12 patients were binocular. Of the 13 patients with a manifest deviation seven had diplopia and six had suppression. Of all paired extra-ocular muscles (EOM), 68% had symmetry of movement within 5 degrees of each other. CONCLUSION: Almost all patients had an exo-deviation. Diplopia was more common than expected. The majority of patients had symmetry of EOM limitation.

Adult↗
PubMed2003

Lower body anatomical distribution of solar ultraviolet radiation on the human form in standing and sitting postures.

Humans undertake their daily activities in a number of different postures. This paper aims to compare the anatomical distribution of the solar erythemal UV to human legs for standing and sitting postures. The exposure ratios to the legs (ratio of the UV exposure to a particular anatomical site compared to the ambient) have been measured with UV dosimeters for standing and sitting postures of a manikin. The exposure ratios for the legs ranged from 0 to 0.75 for the different anatomical sites for the sitting posture in summer (December through February) compared to 0.14 to 0.39 for the standing posture. In winter (June through August) the exposure ratios ranged from 0.01 to 0.91 for sitting to 0.17 to 0.81 for standing. For the anterior thigh and shin, the erythemal UV exposures increased by a factor of approximately 3 for sitting compared to standing postures. The exposure ratios to specific anatomical sites have been multiplied by the ambient erythemal UV exposures for each day to calculate the annual exposures. The annual erythemal exposures to the anterior thigh and ankle were predicted to be higher than 800 MED for humans sitting outdoors each day between noon and 13:00 h Australian Eastern Standard Time (EST). For humans standing outdoors during this time, the annual erythemal UV exposure averaged over each leg site was 436 MED, whereas, the averaged annual erythemal UV exposure was 512 MED for the sitting posture. Similarly, the annual erythemal UV exposure averaged over each of the sites was 173 MED for humans standing outdoors between 09:00 h EST and noon each Saturday morning and 205 MED for humans sitting outdoors during this time. These results show that there is increased risk of non-melanoma skin cancer and malignant melanoma to the lower body if no UV preventative strategies are employed while in a sitting posture compared to a standing posture.

Environmental Exposure↗
PubMed2003

Mutation and biochemical analysis in carnitine palmitoyltransferase type II (CPT II) deficiency.

Carnitine palmitoyltransferase type II (CPT II) deficiency has three basic phenotypes, late-onset muscular (mild), infantile/juvenile hepatic (intermediate) and severe neonatal. We have measured fatty acid oxidation and CPT II activity and performed mutation studies in 24 symptomatic patients representing the full clinical spectrum of disease. Severe and intermediate phenotypes show a clear correlation with biochemical indices and genetic analysis revealed causative mutations in most patients. Studies of mild phenotypes suggest a more complex interaction, with higher residual fatty acid oxidation, a wider range of CPT II activity (10-60%) but little evidence of genotype-phenotype correlation. Residual CPT II mutant protein from myopathic patients shows thermal instability at 41 degrees C. The common 'polymorphisms' V3681 and M647V are strikingly overrepresented in the myopathic patients, the implication being that they may significantly influence the manifestation of clinical disease and could therefore potentially be considered as a susceptibility variants. Among myopathic individuals, males comprised 88% of patients, suggesting increased susceptibility to clinical disease. A small number of symptomatic patients appear to have significant residual CPT II activity (42-60%) The synergistic interaction of partial deficiencies of CPT II, muscle adenosine monophosphate deaminase and possibly other enzymes of muscle energy metabolism in the aetiology of episodic myopathy deserves wider consideration.

AMP Deaminase↗
PubMed2002

Comparison of the solar spectral ultraviolet irradiance in motor vehicles with windows in an open and closed position.

The solar ultraviolet (UV) spectrum was measured by a spectroradiometer located inside two common Australian vehicles: a family wagon and a four-wheel-drive vehicle. The entrance optics of the spectroradiometer was orientated, in turn, on a horizontal plane, towards the driver and passenger windows and towards the windshield. UV spectra were recorded when the vehicles' windows were in an open and closed position. For a typical Australian family wagon, on a horizontal plane inside the vehicle, closing the windows decreased, the total UV irradiance by a factor of 3.2, whilst in a four-wheel drive the irradiance decreased by a factor of 2.1. In order to reduce the likelihood of developing of UV-related eye and skin disorders, drivers should use appropriate UV protection whilst driving a vehicle with the windows in an open position. Results gained from this research provide new findings on the exposure of humans to UV in a vehicle.

Environmental Exposure↗
PubMed2002

The effect of propofol on airway pressures generated by magnetic stimulation of the phrenic nerves.

OBJECTIVES: To assess the effect of propofol on the change in airway pressure produced by diaphragmatic contraction. DESIGN AND SETTING: Prospective, controlled study in patients anaesthetised with propofol in a university hospital. PATIENTS AND METHODS: We stimulated the phrenic nerves before and immediately after induction of anaesthesia in 11 subjects, using a pair of 43-mm mean diameter double magnetic coils and measured the change in airway pressure at the mouth (TwPmo) produced by the resulting diaphragmatic contraction. Supramaximality of stimulation was confirmed with electromyogram and pressure measurements. We recorded the change in Resting End Expiratory Position (REEP) using a spirometer. We applied an approximate correction for the effect of lung volume on the amplitude of twitch pressure produced by diaphragmatic contraction. INTERVENTION: Following the initial stimulations, the patients were anaesthetised with a propofol infusion. Once stable, repeat measurements were made. MEASUREMENTS AND RESULTS: Following induction, REEP fell by mean 0.3 l standard deviation (SD) 0.2 l. TwPmo fell by mean 14.2% SD 14.0% ( P = 0.01), mean 22.3% SD 11.7% corrected ( P < 0.001). Twitch transdiaphragmatic pressure fell by 18.1% and 20.0% (25.8% and 27.7% corrected) in two further subjects studied with oesophageal and gastric balloon catheters. CONCLUSION: Propofol does reduce the effectiveness with which diaphragmatic contraction produces changes of pressure in the airway.

Adult↗
PubMed2002

Assessment of diaphragm function after stellate ganglion block using magnetic stimulation.

Stellate ganglion block is a procedure frequently used for the management of patients with chronic sympathetically mediated pain affecting the arm, neck or head. We studied the effect of stellate ganglion block on ipsilateral phrenic nerve function, and hence diaphragmatic strength, in 11 adult patients with chronic sympathetically mediated pain. Pre- and post-block forced vital capacity (FVC) measurements were recorded using a pneumotachograph and a Magstim nerve stimulator was used to generate pre- and post-block twitch mouth pressures (P(TWM)). This device can be used to stimulate the phrenic nerves and hence the diaphragm. The resulting change in airway pressure was measured at the mouth and has previously been shown to reflect diaphragm strength. There was no statistically significant difference in FVC or P(TWM) pre- or post stellate ganglion block. In conclusion, a stellate ganglion block has no adverse effect on ipsilateral phrenic nerve function or diaphragm strength in healthy adult patients.

Adult↗
PubMed2002

Calf compartment pressures in the Lloyd-Davies position: a cause for concern?

Lower limb compartment syndrome is a rare consequence of surgery where the lithotomy position is maintained for several hours. The aim of this study was to observe the effect of the lithotomy position on lower limb compartment pressure and blood flow to the lower limb in surgical patients having colorectal procedures. We prospectively studied 23 patients undergoing colorectal surgery requiring the lithotomy position and recorded lower limb compartment pressure, and the blood pressure in the upper and lower limbs. The lithotomy position led to a significant (p < 0.001) fall in blood pressure to the lower limb from 87 (SD 16) mmHg to 67.9 (SD 12) mmHg and a significant (p < 0.001) rise in lower limb compartment pressure from 13 (SD 7) mmHg to 31 (SD 12) mmHg. These two effects compromise blood flow to the lower limb in long surgical procedures where the lithotomy position is required. Intermittently lowering the legs and restoring blood flow may prevent compartment syndrome developing.

Adult↗
PubMed2001

Spectral shade ratios on horizontal and sun normal surfaces for single trees and relatively cloud free sky.

Spectral shade ratios, defined as the ratios of the spectral irradiances on horizontal and sun normal planes in the tree shade to those on a horizontal plane in sunlight, were calculated. These planes were in the shade of an isolated medium canopy density tree and a sparse canopy density tree at the tree shade sites of the centre, edge and trunk. The sun normal plane was employed as there are some activities that have exposures to parts of the body that are orientated in a sun normal plane. The horizontal plane shade ratios for the medium density canopy dropped by 47-56% from the ratios in the range 301 to 310 nm to the ratios in the range 391 to 400 nm. In absolute terms, the largest change in the shade ratio of 0.28 was for the centre and edge sites compared to 0.07 for the trunk. Similarly, for the sun normal plane, the ratio dropped by 40-49% with an absolute reduction of 0.19 for the edge and 0.04 for the trunk. For the sparse density canopy, the decrease in the shade ratios over the same wavelength range was a drop by 37-42% on a horizontal plane or, in absolute terms, a reduction by 0.22 for the edge and 0.13 for the trunk. Similarly, the decrease was 34-39% on the sun normal plane or, in absolute terms, a reduction by 0.19 for the edge and 0.12 for the trunk.

Spectrophotometry, Ultraviolet↗
PubMed2001

Antenatal day care units versus hospital admission for women with complicated pregnancy.

BACKGROUND: The use of antenatal day care units is widely recognized as an alternative for inpatient care for women with complicated pregnancy. OBJECTIVES: The objective of this review was to assess the clinical safety, plus maternal, perinatal and psychosocial consequences for the women and cost effectiveness of this type of care. SEARCH STRATEGY: The Group's Specialised Register of Controlled Trials was searched in May 2001 as well as the Cochrane Controlled Trials Register (CENTRAL/CCTR), CINAHL (1982-04 to 1998-10) and Current Contents (Life Sciences/Clinical Medicine 1995-05 to 1999). Conference proceedings of PSANZ (Perinatal Society of Australia and New Zealand) and FIGO (Fédération Internationale de Gynécologie et d'Obstétrie) (1997) were searched. SELECTION CRITERIA: Randomized trial comparing day care with inpatient care for women with complicated pregnancy. DATA COLLECTION AND ANALYSIS: Trial quality was assessed by two reviewers independently. The author of the study was contacted for additional information. Data were extracted by the same two reviewers independently. MAIN RESULTS: One trial involving 54 women was included. This trial was of average quality. It was found that day care assessment for non-proteinuric hypertension can reduce inpatient stay (difference in mean stay: 4.0 days; 95% confidence interval (CI): 2.1 to 5.9 days). Also a significant increase in the rate of induction of labour in the control group was found (4.9 times more likely: 95% CI: 1.6 to 13.8). The other clinical outcomes did not show a statistically significant difference between the control and intervention group. No other significant differences were observed. REVIEWER'S CONCLUSIONS: Admission to day care for non-proteinuric hypertension reduces the amount of time spent in the hospital and proportion of women induced for labour. However, one trial of 54 women is not sufficient to draw sound conclusions. Additional studies are needed to give more solid evidence to confirm the advantages of antenatal day care units.

Cost-Benefit Analysis↗
PubMed2001

Provider attitudes about gaining consent for perinatal autopsy.

OBJECTIVE: To examine the attitudes of neonatologists, obstetricians, midwives, and neonatal nurses toward perinatal autopsy and survey physicians about whom they perceive influence women's decisions on autopsy consent. METHODS: A postal survey that incorporated a questionnaire of eight fictitious case scenarios and combined three factors (confidence of antemortem diagnosis, intention to have future pregnancy, and parental attitude toward autopsy) in various permutations was sent to various Australian physicians and nurses (all consultant neonatologists working in neonatal intensive care units and a sample of consultant obstetricians, midwives, and neonatal nurses in level III maternity hospitals). Respondents were asked to rate how likely they were to seek consent for or suggest autopsies on a seven-point Likert scale (1 = certainly will not, 7 = certainly will). Interactions between factors and respondents were measured by analysis of variance, and differences were compared using Mann-Whitney U, chi(2), and generalized estimating equation tests. RESULTS: The overall response rate was 70% (neonatologists 57%, obstetricians 62%, midwives 77%, and neonatal nurses 75%). Neonatologists (median score 7, interquartile range 7, 7) were more likely to ask for autopsies than neonatal nurses (5; 2, 6) (P <.001), as were obstetricians (7; 7, 7) compared with midwives (6; 3, 7) (P <.001). Physicians rated midwives and neonatal nurses as having some to substantial influence on mothers' decisions about consent for autopsy. CONCLUSION: Physicians are not averse to seeking consent for perinatal autopsies. Midwives and nurses are influenced by the three factors studied, which might negatively influence the consent rate for perinatal autopsies. Intervention strategies aimed at changing nurses' attitudes should be considered.

Attitude of Health Personnel↗
PubMed2001

Comparison between seasons of the ultraviolet environment in the shade of trees in Australia.

BACKGROUND/PURPOSE: This paper has considered the erythemal UV (UVery), UVA and visible irradiances in the shade of Australian trees for each season at a sub-tropical southern hemisphere site. METHODS: The irradiances in tree shade have been measured with radiometers as a percentage of the irradiances in the sun for each season of the year. RESULTS: Although the solar irradiances are lower in winter, the percentages of the UV in tree shade compared to the UV in full sun are marginally higher (by up to 7%) in the winter compared to summer. The range of percentages for UVery was up to double that of the percentages of the visible waveband. The percentages for UVery were also higher than for the UVA waveband. The percentages of the irradiances in the tree shade compared to full sun are 8-14% lower at noon compared to the morning and afternoon for the UVery waveband. The ratio of UVA to UVery is lower in the tree shade compared to the full sun. CONCLUSIONS: The UVA to UVery ratio is expected to be even lower in the tree shade as a result of ozone depletion. This, combined with the visible irradiances in the tree shade not being a reliable indication of the biologically damaging UV irradiances, has consequences for public health and skin cancer prevention.

Australia↗
PubMed2001

Compartment syndrome associated with the Lloyd Davies position. Three case reports and review of the literature.

The Lloyd Davies position was developed to facilitate access to the pelvis for gynaecological, urological and colorectal procedures. Previous case reports have demonstrated that prolonged adoption (> 4 h) of this position has been associated with the development of bilateral compartment syndrome of the calves. All three patients reported here suffered severe bilateral calf pain despite the use of thoracic epidurals. All three cases required three-compartment fasciotomies and, 6 months after surgery, were all still severely disabled as a consequence of the compartment syndrome. These case reports stress the dangers of use of the Lloyd Davies position for prolonged procedures and demonstrate that some patients are at risk after relatively short periods (< 3 h). Previous case reports and clinical studies have focused on the effect of limb elevation in stirrups on the arterial pressure in the lower limb. We review the pathophysiology of compartment syndrome and consider factors other than a decrease in arterial pressure that may predispose to compartment syndrome during adoption of the Lloyd Davies position.

Compartment Syndromes↗