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Biomedical subjects

M Birch

Publications and source records attributed to M Birch.

At least 19 recordsLinked to original sources
PubMed2026

Addressing the dual-use of antifungals and fungal antimicrobial resistance (fAMR) through a One Health approach.

Fungal antimicrobial resistance (fAMR) is accelerating, driven in part by the dual-use of antifungal modes of action in agriculture and medicine, threatening therapy. Addressing this challenge requires a unified One Health response that balances agricultural productivity, economic stability, and human and animal health. By focusing on the United Kingdom's policy approach, we argue that current efforts are constrained by fragmented governance, surveillance and regulation. To resolve this, we propose three policy recommendations: 1. a cross-government fAMR body, 2. mandatory environmental and clinical surveillance, and 3. for fungicide approvals to look beyond crop pathogens and integrate risk assessments for potential hotspots of resistance selection in human fungal pathogens. These measures will safeguard current and future antifungals while providing much-needed regulatory clarity and will be translatable to other national and regional contexts.

Journal Article↗
PubMed2006

The role of mitochondrial haplogroups in primary open angle glaucoma.

AIM: To investigate a possible association between mitochondrial haplogroups and primary open angle glaucoma (POAG). METHODS: Genomic DNA was extracted from 140 POAG patients and 75 healthy individuals. Restriction enzyme digest analysis of polymerase chain reaction (PCR) amplified fragments was used to determine the mitochondrial haplogroup of each patient and control. RESULTS: The median age was 73 years for the POAG patients (range 51-87, SD 8.01) and 78 years for the controls (range 68-90, SD 4.4). Mean IOP was 20.8 mm Hg for the patients (SD 2.6) and 16.2 mm Hg for the controls (SD 3.4). Median cup/disc ratio was 0.8 and 0.3 for patients and controls respectively. No statistically significant difference was found in the haplogroup distribution between the POAG patients and the healthy individuals (Fisher's exact test). CONCLUSION: In this cohort, mitochondrial haplogroups do not appear to contribute to the pathogenesis of POAG.

Aged↗
PubMed2005

Reduction of exit-site infections of tunnelled intravascular catheters among neutropenic patients by sustained-release chlorhexidine dressings: results from a prospective randomized controlled trial.

Exit-site and tunnel infections of tunnelled central intravascular catheters are a frequent source of morbidity among neutropenic patients and may necessitate catheter removal. They require antimicrobial therapy that increases healthcare costs and is associated with adverse drug reactions. A prospective randomized clinical trial was conducted among adult patients undergoing chemotherapy in a haematology unit. Tunnelled intravascular catheters were randomized to receive the control of a standard dressing regimen as recommended by the British Committee for Standards in Haematology, or to receive the intervention of a sustained-release chlorhexidine dressing. Follow-up data were available in 112 of 114 tunnelled intravascular catheters which were randomized. Exit-site or combined exit-site/tunnel infections occurred in 23 (43%) of 54 catheters in the control group, and five (9%) of 58 catheters in the intervention group [odds ratio (OR) for intervention group compared with control group =0.13, 95% confidence intervals (CI) 0.04-0.37, P<0.001]. More tunnelled intravascular catheters were prematurely removed from the control group than the intervention group for documented infections [20/54 (37%) vs 6/58 (10%), OR=0.20, 95%CI 0.53-0.07]. However, there was no difference in the numbers of tunnelled intravascular catheters removed for all proven and suspected intravascular catheter-related infections [21/54 (39%) vs 19/58 (33%)], or in the time to removal of catheters for any reason other than death or end of treatment for underlying disease. Thus chlorhexidine dressings reduced the incidence of exit-site/tunnel infections of indwelling tunnelled intravascular catheters without prolonging catheter survival in neutropenic patients, and could be considered as part of the routine management of indwelling tunnelled intravascular catheters among neutropenic patients.

Administration, Topical↗
PubMed2005

Use of reactance to estimate transpulmonary resistance.

This study examines the relationship of respiratory system resistance (R(rs)) and reactance (X(rs)) measured by forced oscillometry with transpulmonary resistance (R(L)) measured by oesophageal manometry. Simultaneous forced oscillometry using a single frequency of 5 Hz and oesophageal manometry were performed on five asthmatics during bronchoprovocation. The data obtained were used to derive prediction equations for R(L) from oscillometric parameters, which were tested on a further six asthmatics and 35 nonasthmatic subjects. In the first five asthmatic subjects, R(L) correlated more strongly with X(rs) than with R(rs). In the second set of asthmatics, R(L) ranged 0.0005-4.57 kPa.s.L(-1), with a median of 0.21 kPa.s.L(-1). The R(L) values predicted from X(rs) showed a mean+/-sd difference of -0.067+/-0.25 kPa.s.L(-1) compared with the values measured in this set of patients. X(rs) in subjects with other respiratory conditions appeared to follow the same relationship with R(L) as in asthmatics. Lumped element modelling suggested that the linear relationship between X(rs) and R(L) was a consequence of the increasing contribution of central and upper airway wall shunts as peripheral airway resistance rose, and that this effect was much larger than that due to changes in static elastance. In conclusion, the reactance of the respiratory system can predict transpulmonary resistance more accurately than can the resistance of the respiratory system.

Adult↗
PubMed2002

Investigation into the thermal distribution of microwave helical antennas designed for the treatment of Barrett's oesophagus.

A set of helical microwave antennas was designed to investigate their potential use in thermal therapy of Barrett's oesophagus. The antennas had a diameter of up to 3.3 mm and various lengths between 20 and 37 mm; these were designed to operate at 915 MHz. Sets of polytetrafluoroethylene (PTFE) formers were constructed to improve the repeatability and reproducibility of the helix manufacture. Small diameter copper wire was wound over the formers and connected to the coaxial cable at the inner and outer conductor junctions. The power deposition profiles of the antennas were measured in a muscle-equivalent phantom using an infrared camera. The effects of antenna length and coil spacing were characterized. It was observed that uniform temperature profiles along the antenna length were achieved with a length of wire of 99 mm +/- 2 mm. The effective heating length (length of the antenna that exhibits > 50% of the maximum temperature rise) was comparable to the antenna length. The radial penetration depth of 50% of the antenna surface temperature for the optimum 20 mm antenna was 2.5 mm from the antenna outer surface.

Barrett Esophagus↗
PubMed2001

Maternity care providers' attitudes and practices concerning HIV testing during pregnancy; results of a survey of the Canterbury and upper South Island region.

AIMS: To assess current attitudes and practice toward antenatal human immunodeficiency virus (HIV) risk assessment, HIV testing and barriers towards implementation of these among midwives, general practitioners (GPs) and obstetricians in the upper South Island METHODS: A survey was conducted among maternity care providers by anonymous self-administered questionnaire. Most questions were dichotomous, forced choice or Likert scale format but there were four open- ended questions asking for a written response. RESULTS: The response rate was 57% overall. The main finding was that 275 (66%) of respondents assessed risk of HIV in less than 10% of patients, and 328 (midwives 93, 85%; GP's 226,77%; obstetricians 9,64%) respondents had performed less than three HIV tests in the past twelve months. Most respondents strongly agreed that detection of HIV during pregnancy is beneficial to mother 318 (83%) and to baby 367 (96%) and to mother prior to pregnancy 353 (92%). 202 (52%) supported and 44 (11%) were opposed to an antenatal screening programme in New Zealand. Most knew how to assess risk for HIV saw themselves as having an important role in antenatal HIV testing, and were comfortable performing risk assessment. Multiple reasons for current practices were offered, including perceived reluctance by women to be tested, lack of time, skills, knowledge and support services, and low rates of HIV in the community. CONCLUSIONS: The current policy of routine HIV risk assessment is not working among respondents. A systematic reassessment and implementation of a workable strategy needs to be undertaken in New Zealand.

AIDS Serodiagnosis↗
PubMed2001

Human eosinophils induce mucin production in airway epithelial cells via epidermal growth factor receptor activation.

Eosinophil recruitment and mucus hypersecretion are characteristic of asthmatic airway inflammation, but eosinophils have not been shown to induce mucin production. Because an epidermal growth factor receptor (EGFR) cascade induces MUC5AC mucin in airways, and because EGFR is up-regulated in asthmatic airways, we examined the effect of eosinophils on MUC5AC mucin production in NCI-H292 cells (a human airway epithelial cell line that produces mucins). Eosinophils were isolated from the peripheral blood of allergic patients, and their effects on MUC5AC mucin gene and protein synthesis were assessed using in situ hybridization and ELISAs. When IL-3 plus GM-CSF or IL-3 plus IL-5 were added to eosinophils cultured with NCI-H292 cells, MUC5AC mucin production increased; eosinophils or cytokines alone had no effect. Eosinophil supernatant obtained by culturing eosinophils with IL-3 plus GM-CSF or IL-3 plus IL-5 also increased MUC5AC synthesis in NCI-H292 cells, an effect that was prevented by selective EGFR inhibitors (AG1478, BIBX1522). Supernatant of activated eosinophils induced EGFR phosphorylation in NCI-H292 cells. Supernatant of activated eosinophils contained increased concentrations of TGF-alpha protein (an EGFR ligand) and induced up-regulation of TGF-alpha expression and release in NCI-H292 cells. A blocking Ab to TGF-alpha reduced activated eosinophil-induced MUC5AC synthesis in NCI-H292 cells. These results show that activated eosinophils induce mucin synthesis in human airway epithelial cells via EGFR activation, and they implicate TGF-alpha produced by eosinophils and epithelial cells in the EGFR activation that results in mucin production in human airway epithelium.

Adult↗
PubMed2001

Respiratory input impedance measurement: forced oscillation methods.

The paper reviews how forced oscillation techniques (FOT) for measuring respiratory input impedance Zrs,in have recently been used in clinical applications. Zrs,in is clinically relevant, as it provides data on both the resistive, Rrs, and nonresistive, Xrs, components of the respiratory system. Additionally, when excitatory test signals extending into low- (<4 Hz) or high-frequency (>100 Hz) ranges are used, reliable partitioning of lung tissue from airway components is feasible. Adult and paediatric studies examining the use of Zrs,in for routine lung-function assessment, sleep and mechanical ventilation are reviewed. For clinicians, Zrs,in repeatable and sensitive to airway resistance. It is helpful for assessing unco-operative and severely obstructed patients, for monitoring mechanics during artificial ventilation and for tracking airway closure during sleep studies. For paediatricians, longitudinal studies of the growth and development of the respiratory system can also be made using Zrs,in. Forced oscillation techniques, however, require further standardisation, and Zrs,in is limited by upper-airway shunt artifacts. In conclusion, measurement of Zrs,in using FOT is an important and sophisticated non-invasive lung-function test, showing good potential for future clinical applications.

Airway Resistance↗
PubMed2001

Clinical comparison of the measurement of the IOP with the ocular blood flow tonometer, the Tonopen XL and the Goldmann applanation tonometer.

PURPOSE: In addition to measuring ocular blood flow, the ocular blood flow tonometer (OBF) can also be set to solely record intraocular pressure (IOP). In this mode it provides a quick means of tonometry which may allow nursing staff to be more easily trained in its use than conventional Goldmann tonometry. With a view to its eventual use in nurse-led clinics we undertook a study to compare both the OBF tonometer and our currently favoured nurse practitioners tonometer the tonopen XL with Goldmann tonometry. METHOD: IOP was measured in 99 eyes with all three tonometers in a random order. RESULTS: There was not any statistically significant difference between the measurements of all three tonometers. CONCLUSIONS: It is concluded that OBF tonometer can provide clinically useful measurements of intraocular pressure which may in fact be more accurate than the tonopen, however, our opinion is that it possibly is not suitable for a universal glaucoma clinics application.

Adult↗
PubMed2001

An analogue instrument for the measurement of respiratory impedance using the forced oscillation technique.

The successful development of non-invasive assisted ventilation via a nasal mask has led to the requirement for improved methods of monitoring the respiratory system. Measurements of respiratory impedance during assisted ventilation using acoustic methods are showing considerable promise in providing this clinical data. The method involves imposing very low amplitude acoustic oscillations onto the spontaneous or assisted respiratory airflow. The subsequent interaction with the respiratory system modifies the pressure and flow relationship of the forced oscillations. The ratio of pressure to flow can be used to measure in real time the absolute value of respiratory input impedance. As a result a versatile, non-invasive and repeatable profile of respiratory mechanics is obtained. Using a 5 Hz conventional forced oscillation frequency, data highly sensitive to airflow obstruction and capable of tracking mechanical events and responses become available to the clinician. Recent studies with ventilated and sleeping subjects confirm future potential for the forced oscillation technique in vivo. We describe an instrument named the respiratory impedance monitor (5 Hz), which utilizes the forced oscillation technique (FOT). This fully developed device is designed in accordance with agreed international clinical guidelines. Comparative clinical data from normal subjects and patients with chronic obstructive pulmonary disease is presented.

Air Pressure↗
PubMed2001

Prospective study of 424 cases of Staphylococcus aureus bacteraemia: determination of factors affecting incidence and mortality.

BACKGROUND: Staphylococcus aureus bacteraemia (SAB) is a common complication of S. aureus infection and is associated with a high mortality. AIMS: To document prospectively the pattern of illness associated with SAB in New Zealand and, by recording patient demographic factors and clinical features, to identify risk factors associated with a poor outcome. METHODS: From 1 July 1996 to 31 December 1997, adults with SAB were prospectively studied in six tertiary care hospitals. All information obtained from patients' records was recorded on worksheets and transferred to a computerized spreadsheet for analysis. RESULTS: There were 424 patients with SAB. Maori (relative risk (RR)= 1.8, 95% confidence interval (CI) = 1.3-2.6) and Pacific Island people (RR = 4.0, 95% CI = 3.1-5.3) were significantly more likely than people of European descent to acquire SAB, but not to die from the infection. Fifty per cent of cases were community acquired. A source was identified for 85%: intravenous catheter (31%), primarily hospital acquired, and skin/soft tissue (22%), primarily community acquired, were the most common foci. The 30-day mortality was 19%, 83% of whom died within 2 weeks. Risk factors for a poor outcome were: increasing age above 60, female sex (RR = 1.4, 95% CI = 1.0-2.1), diabetes mellitus (RR = 1.5, 95% CI = 1.0-2.4), immunosuppression (RR = 1.5, 95% CI = 1.0-2.4), pre-existing renal impairment (RR = 1.8, 95% CI = 1.2-2.7), malignancy (RR= 2.2, 95% CI = 1.4-3.5), lung as a source (RR = 2.8, 95% CI = 1.9-4.2) and unknown source (RR = 2.3, 95% CI = 1.5-3.3). Mortality was also accurately predicted by two multifactor scoring systems. There was a low rate of methicillin resistance (5%). CONCLUSIONS: Staphylococcus aureus bacteraemia is more likely to occur in certain ethnic groups, while mortality is associated with other identifiable risk factors and continues to be high. Intravenous catheters remain the most common and most preventable cause of SAB.

Adolescent↗
PubMed2000

Best5: a novel interferon-inducible gene expressed during bone formation.

Regulation of bone formation is important in the pathogenesis of many conditions such as osteoporosis, fracture healing, and loosening of orthopedic implants. We have recently identified a novel rat cDNA (best5) by differential display PCR that is regulated during osteoblast differentiation and bone formation in vitro and in vivo. Expression of best5 mRNA is induced in cultures of osteoblasts by both interferon-alpha (IFN-alpha) or IFN-gamma. Whereas IFN-alpha induced a rapid, transient induction of best5 expression peaking at 4-6 h poststimulation, IFN-gamma elicited a more prolonged induction of best5 expression, which remained elevated 48 h poststimulation. A polyclonal antibody generated to a peptide derived from the best5 coding region recognized a 27 kDa protein on Western blot analysis of osteoblast lysates. We localized BEST5 protein in osteoblast progenitor cells and mature osteoblasts in sections of rat tibiae and in sections of bones loaded in vivo to induce adaptive bone formation. Best5 may therefore be a fundamental intermediate in the response of osteoblasts to stimuli that modulate proliferation/differentiation, such as interferons or mechanical loading. These findings highlight the close interactions between the immune system and bone cells and may open new therapeutic avenues in modulating bone mass.

Amino Acid Sequence↗
PubMed2000

Concentrations of trace minerals in the spinal cord of horses with equine motor neuron disease.

OBJECTIVE: To compare concentrations of trace minerals in the spinal cord of horses with equine motor neuron disease (EMND) with those of horses without neurologic disease (control horses). ANIMALS: 24 horses with EMND and 22 control horses. PROCEDURE: Spinal cord trace mineral concentrations in horses with EMND and control horses were analyzed by use of inductively coupled plasma atomic emission spectroscopy (calcium, phosphorus, sodium, potassium, magnesium, copper, iron, manganese, nickel, zinc, aluminum, cobalt, and chromium), atomic absorption spectrophotometry (lead and cadmium), flameless atomic absorption (mercury), and fluorometry (selenium). RESULTS: Copper concentration was significantly higher in the spinal cord of horses with EMND, compared with control horses; spinal cord concentrations of all other trace minerals were similar between groups. CONCLUSION AND CLINICAL RELEVANCE: Among spinal cord trace minerals investigated in the study, only copper concentrations were significantly different between horses with EMND and horses without neurologic disease, which suggests that copper may be involved in the pathogenesis of EMND. An hypothesis of oxidative injury in this disease is supported by the finding of increased copper concentrations in the spinal cord and by low vitamin E concentrations reported by other researchers.

Aluminum↗
PubMed1999

Localisation of connective tissue and inhibition of autofluorescence in the human optic nerve and nerve head using a modified picrosirius red technique and confocal microscopy.

The use of picrosirius red to localise connective tissue in thin tissue sections viewed by bright-field microscopy is well documented. Its use on thin tissue sections imaged by fluorescence confocal microscopy has also been reported. Here we describe modifications to published procedures that allow picrosirius red staining of thick 60-microm sections and their subsequent analysis by confocal microscopy. The use of phosphomolybdic acid pre-treatment was found to be essential for confocal analysis; in addition to preventing non-specific staining, it also quenched tissue autofluorescence. By incubating sections free-floating, pre-treating them with phosphomolybdic acid for 30 min and imaging them using an argon ion laser we were able to use confocal microscopy to image the entire depth of 60-microm human optic nerve and nerve head sections stained with picrosirius red. The application of this modified picrosirius red and confocal microscopy technique should be useful for analysing the three-dimensional structure of the optic nerve and other tissues with a similarly complex arrangement of connective tissue.

Adult↗